rebond documentation

The foam used in rebonded foam product is documented by our supplier as 100% recycled. This content is a mix of post-consumer and pre-consumer content, that which cannot be identified as it changes from batch to batch, therefore, in the calculations the lesser value: pre-consumer.

Only 50% of this weight may count towards the recycled content value of the product in accordance with the US Green Building Council LEED guidelines for New Construction/Schools MR credit 4.1 and 4.2:

Use materials with recycled content such that the sum of post-consumer recycled content plus one-half the pre-consumer content constitutes at least 10% [20% for MR 4.2] (based on cost) of the total value of the materials in the project.

Neither the supplier, nor we could claim, however, that the entire products weight is recycled because the adhesive used to bind the foam is a virgin material. Our supplier felt it was an trade secret, and would not disclose the exact percentage of glue to foam ratio. To create an accurate percentage, 4 patents for the material have been referenced, with an average binder amount of 13% of total product by weight. Because percentages fluctuate from batch to batch, we found this to be the most accurate way of determining the average percentage for any rebonded foam product.

Attached also, is the letter from the manufacturer stating 100% recycled foam content. We feel that armed with this specific documentation, and a written explanation during the submittal process, that this material can be successfully atributed to MR credits 4.1 and 4.2: Recycled Content.

Rebonded Foam Documentation

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Title:ANTI-MICROBIAL CARPET UNDERLAY AND METHOD OF MAKING

Document Type and Number:United States Patent Application 20070122608

Kind Code:A1

Abstract:A method for making antimicrobial rebonded carpet pad includes mixing zinc pyrithione with a polyol to form an antimicrobial polyol mixture concentrate,blending the antimicrobial polyol mixture concentrate with a binder stream, mixing the binder with foam particles and curing the binder. The percentage of zincpyrithione mixed with the polyol and the addition ratio of the antimicrobial polyol mixture concentrate with the binder stream are selected to provide an overallconcentration of zinc pyrithione in the binder of at least about 7500 ppm. The particles and binder are cured into a block and sliced to form carpet pad.

Inventors:Gilder, Stephen D. (Chula Vista, CA, US)Lovato, Martin J. (Cape Coral, FL, US)Griggs, William A. (Southaven, MS, US) Plaque It!

Sponsored by:Flash of Genius

Application Number:11/627610

Publication Date:05/31/2007

Filing Date:01/26/2007

View Patent Images:Images are available in PDF form when logged in. To view PDFs, Login or Create Account (Free!)

Referenced by:View patents that cite this patent

Export Citation:Click for automatic bibliography generation

Assignee:L&P Property Management Company (South Gate, CA, US)

Primary Class:428/304.400

ANTI-MICROBIAL CARPET UNDERLAY AND METHOD OF MAKIN... http://www.freepatentsonline.com/y2007/0122608.html?query=rebond+f...

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International Classes:B32B3/26

Attorney, Agent or Firm:Conley Rose P. C. (5700 GRANITE PARKWAY, SUITE 330, PLANO, TX, 75024, US)

Claims:What we claim as our invention is:

1. A method for making rebonded carpet pad, comprising: mixing zinc pyrithione with a polyol to form an antimicrobial polyol mixture concentrate, blendingthe antimicrobial polyol mixture concentrate with a binder stream, and selecting a percentage of zinc pyrithione mixed with the polyol and an addition ratio ofthe antimicrobial polyol mixture concentrate with the binder stream to provide an overall concentration of zinc pyrithione in the binder of at least about 7500ppm.

2. The method for making rebonded carpet pad according to claim 1, further comprising: mixing zinc pyrithione with a triol polyol to a 20% strengthantimicrobial polyol mixture concentrate, and blending the 20% strength antimicrobial polyol mixture concentrate with a binder stream at at least a 3.90%addition level.

3. The method according to claim 2, further comprising blending the 20% strength antimicrobial polyol mixture concentrate with a binder stream at a 3.90% to6.5% addition level.

4. The method according to claim 1, further comprising: mixing the binder with foam particles.

5. The method according to claim 4, wherein the ratio of binder to foam particles is about 1:10 and results in an overall concentration of zinc pyrithione in thecarpet pad of at least about 750 ppm.

6. The method according to claim 4, further comprising shaping the mixture of binder and foam particles into a block, curing the binder and slicing the block toform carpet pad.

7. The method according to claim 6, further comprising laminating a film to at least one side of the carpet pad.

8. The method according to claim 7, wherein the film comprises an effective amount of an anti-microbial compound.

9. A carpet underlay made by the method of claim 6.

10. A carpet underlay made by the method of claim 7.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONSThis is a Divisional Application of U.S. patent application Ser. No. 10/840,309, filed May 6, 2004, entitled Anti-Microbial Carpet Underlay and Method ofMaking, which claims the benefit under 35 U.S.C. 119 of U.S. provisional application Ser. No. 60/506,688 filed Sep. 26, 2003 and entitled Anti-MicrobialCarpet Pad and Method of Making, both of which are hereby incorporated herein by reference for all purposes.

FIELD OF THE INVENTIONThis invention relates to antimicrobial rebond ed carpet underlay and more particularly to a method of making such underlay by mixing an anti-microbial agentin binder used to make the rebond ed carpet underlay.

BACKGROUND OF THE INVENTIONCarpet, especially wall-to-wall carpet, is normally installed with an underlay, often in the form of a foam pad or cushion. Moisture, dirt, food particles, andother debris tend to filter through the carpet to the pad. These conditions provide a breeding ground for various bacteria and mold that may produce undesirableodors, cause degradation of the carpet and/or pad, and/or contribute to a poor indoor air quality environment for occupants of the premises.

A typical carpet pad consists of ground polyurethane foam particles of a specific size range that are rebond ed back together to form a continuous foam pad ofvarious densities and thickness. Typically, carpet pad ranges in density from four to eight pounds per cubic foot. Rebond ed pad is made from recycledpolyurethane foam, typically from scraps of foam reclaimed from padding used in furniture, bedding, and automobile seating. The scraps are often of differentsizes and colors. The rebond ed foam is produced by grinding or chopping the scraps, mixing the chopped scraps with a binder, curing the binder, and slicing theresulting block of rebond ed foam particles into a desired pad thickness. The binder may typically form ten percent of the weight of the final rebond ed pad.Various films or webs may be bonded to one or both sides of the pad for various purposes.

SUMMARY OF THE INVENTIONA method of making antimicrobial rebond ed carpet pad includes mixing zinc pyrithione with a polyol to form an antimicrobial polyol mixture concentrate, andblending the antimicrobial polyol mixture concentrate with a binder stream used to make rebond ed carpet pad.

In an embodiment, the percentage of zinc pyrithione mixed with the polyol and the addition ratio of the antimicrobial polyol mixture concentrate with thebinder stream are selected to provide an overall concentration of zinc pyrithione in the binder of at least about 7500 ppm.

In one embodiment, an antimicrobial carpet underlay comprises a rebond ed pad comprising particles of foam joined together with a binder prepared accordingthe described method.

BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a cross sectional view of a carpet underlay according to one embodiment of the present invention.

FIG. 2 is a block diagram of a binder mixing system used in making rebond ed pad for testing the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSFIG. 1 is a cross sectional illustration of an antimicrobial carpet underlay 10 which may be made according to one embodiment of the present invention. Theunderlay 10 includes a rebond ed pad portion 12 including a number of small pieces of foam 14 bonded together by binder 16. The foam pieces 14 may


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typically be ground or chopped scraps of polyurethane foam used in making furniture. The underlay 10 may also include a film 18 bonded to at least onesurface of the pad 12, in this case the upper surface of the pad 12. The film 18 is typically preferred to facilitate laying carpet on top of the underlay 10 and forresisting the flow of fluids into the pad 12, e.g. when fluids are spilled on carpet installed over the pad 12. A film 18 may also be laminated to the lower side ofthe pad 12 if desired. In the present invention, the carpet underlay 10 is resistant to the growth of bacteria and mold on and within the underlay 10. Thisantimicrobial resistance is achieved by adding an effective amount of an antimicrobial compound to the pad 12 and/or to the film 18, as described in more detailbelow.

In one embodiment, an effective biocide, or antimicrobial, compound known as zinc pyrithione (e.g. the material sold under the trademark ZINC OMADINE byArch Chemicals Inc.) is incorporated into rebond ed carpet pad 12 by the following method. The chemical name for this compound is Bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-(T-4)Zinc. The zinc pyrithione in powdered form is mixed with a triol polyol of a molecular weight typically ranging from 3000 to3500 to form a 20% strength antimicrobial/polyol mixture concentrate. Then, the 20% antimicrobial/polyol mixture concentrate is added to a binder stream at a3.90% to 6.50% addition level to render a zinc pyrithione concentration of between 7500 to 12500 ppm in the binder 16. The antimicrobial/polyol mixtureconcentrate and binder stream are preferably held at between about 90 and about 100 degrees F. during mixing and use. The binder 16 is typically composed of aromatic oil, triol polyol, and polymeric MDI. The binder is added to ground foam particles, mixed together, compressed, injected with steam, and driedin the form of a large block of rebond ed foam particles. The block is then sliced into thicknesses suitable for carpet pad, e.g. three-eighth to five-eighth inch, toproduce the rebond ed foam pad 12. The binder to ground foam weight ratio is approximately 1:10. The final concentration of Zinc Pyrithione in the rebond edpad 12 is therefore from about 750 ppm to about 1250 ppm.

If desired, the particular concentration of zinc pyrithione in the antimicrobial/polyol mixture concentrate may be selected to be more or less than the 20%concentration used in this embodiment. The addition level of the antimicrobial/polyol mixture concentrate in the binder 16 may then be adjusted to achieve azinc pyrithione concentration of at least about 7500 ppm and preferably between about 7500 to about 12500 ppm in the binder 16.

If desired, a binder 16 to ground foam weight ratio of more or less than 1:10 may be used. If other ratios are used, the particular concentration of zinc pyrithionein the antimicrobial/polyol mixture concentrate and/or the addition level of the antimicrobial/polyol mixture concentrate in the binder 16 may then be adjustedto achieve a final concentration of Zinc Pyrithione in the rebond ed pad 12 from about 750 ppm to about 1250 ppm.

FIG. 2 illustrates a mixing system used in making binder 16 for testing the present invention. A method for making binder 16 will be described with reference toFIG. 2. A mix tank 20 included a thirty-gallon drum and a vortex type mixer. Eighty pounds of polyol and twenty pounds of powdered zinc pyrithione wereplaced in tank 20 and mixed for at least three hours. A transfer pump 22 was used to pump the mixture from mix tank 20 to a run tank 24, which also includes avortex mixer. The antimicrobial/polyol mixture concentrate in the run tank 24 was mixed constantly during production. If the mixer is turned off for anysignificant period of time, it should be restarted at least two hours prior to use in production of rebond ed pad 12.

During production of rebond ed pad 12, a variable speed Watson Marlow pump 26 was used to flow the antimicrobial/polyol mixture concentrate from the runtank 24 at a controllable rate. The rate is controlled by a control panel 28 and a variable frequency drive 30. The discharge side of pump 26 is connected to thevacuum side of a binder pump 32. A tank 34 of binder also has an outlet connected to the vacuum side of a binder pump 32. The discharge side of pump 32 isconnected to a static mixer 36. The outlet 38 of mixer 36 is coupled to a blender where polyurethane particles 14 are mixed with binder 16 to produce thefinished rebond ed polyurethane pad 12.

During the operation of the system of FIG. 2, it is preferred that the antimicrobial/polyol mixture concentrate in the mix tank 20 and run tank 24 be maintainedat a temperature of between about 90 and about 100 degrees F. during mixing and production operations. Likewise, the binder tank 34 is preferable maintainedwithin the same temperature range.

It is sometimes desirable to include laminating film 18 on one or both surfaces of carpet pad 12. For example, such a film 18 may facilitate laying and stretchingof carpet by allowing the carpet to slide easily on top of the pad 12 and avoiding undesirable movement or buckling of the pad 12. The film may also preventfluids spilled on carpet from penetrating into the pad 12. In one embodiment of the present invention, an antimicrobial laminating film 18 is laminated onto oneor both surfaces of a carpet pad. The carpet pad may or may not include an antimicrobial compound as disclosed above.

The anti-microbial laminating film 18 of this embodiment inhibits the growth of certain bacteria and fungus when used in combination with prime polyurethanefoam pad or rebond ed polyurethane foam pad 12 as carpet underlay. The anti-microbial film may be thermally laminated to the top and/or bottom surfaces ofprime polyurethane foam pad or re-bonded polyurethane flexible foam pad 12 where it acts as a barrier to inhibit the growth of microbes that accumulate on thesurfaces of carpet underlay. This film 18 may also inhibit the growth of microorganisms in other products where this film can be used as a lamination barrier.

In this embodiment, a 0.45 to 0.50 mil monolayer blown film 18 includes between 500 and 1500 ppm of the antimicrobial compound zinc pyrithione (e.g. thematerial sold under the trademark ZINC OMADINE by Arch Chemicals Inc.). The chemical name for this compound is Bis(1-hydroxy-2(1H)-pyridinethionato-O,S)-(T-4)Zinc. The zinc pyrithione powder is incorporated at 10% by weight into a LLDPE, linear low density polyethylene, resin concentrate supplied byPolyChem Alloy, Inc. under the trademark POLYSEPT 554Z. The chemical description of the resin concentrate is Mercaptopyridine-N-oxide inPolypropylene. This resin concentrate has a specific melt index of 20 grams/10 mins. and 0.93 density. About 1% to about 3% by weight of this concentrate isthen blended with a LLDPE/Copolymer resin mixture. Due to thermal breakdown of zinc pyrithione during processing of the film, the initial 10% concentrationof zinc pyrithione in the concentrate may be effectively reduced to less than 6%. After mixing with the resin mixture and processing it into a film, the neteffective concentration of zinc pyrithione in the processed film is about 500 ppm to 1500 ppm. Suitable copolymer resins may be EVA, EMA, or EMM. Thecopolymer resin consists of approximately 60-70% by weight of the total mixture. The remaining mixture is 30-40% LLDPE by weight, including the 1-3%LLDPE concentrate treated with zinc pyrithione. The blended resins may then be extruded at between 450 and 550 degrees F. with a blow up ratio, i.e. bubblediameter to die diameter, of between 1.8 and 2.5:1. It is preferred that the extrusion temperature be kept below 500 degrees F. to minimize thermal breakdownof the zinc pyrithione.

It is apparent that zinc pyrithione powder may be incorporated at more or less than 10% by weight into the resin concentrate. If other addition levels areselected, the percentage of the concentrate blended with the LLDPE/Copolymer resin mixture may be adjusted to achieve a net effective concentration of zincpyrithione in the processed film of from about 500 ppm to 1500 ppm.

The anti-microbial treated film may be thermally laminated (e.g. at about 250-450 degrees F., 0.5 sec dwell time) to one or both sides of a prime polyurethanefoam pad or rebond ed pad 12 which may typically be from about three-eighth inch to about five-eighth inch thick or other desired thickness. Other laminatingmethods may be used if desired, e.g. by use of an adhesive. The anti-microbial film may be laminated to an anti-microbial treated pad or non-anti-microbialtreated pad. The anti-microbial film may also be laminated to another anti-microbial treated or untreated film for lamination to anti-microbial treated pad ornon-anti-microbial treated pad.

Biocidal effectiveness of the rebond ed carpet pad 12 and/or film 18 according the present invention may be determined by measuring inhibition of growth ofbacterial and/or fungus using AATCC (American Association of Textile Chemists and Colorists) 174, ASTM E2180-1, and ASTM D 3273 test protocolscompared to non-treated control standards. The AATCC 174 protocol was developed for determining the antimicrobial activity of new carpet materials.

A number of specimens of carpet underlay 10 were made by methods described above, with various concentrations of zinc pyrithione in the binder 16 and film18 for testing to determine levels that provide an effective antimicrobial effect. The specimens included a film 18 on one side as illustrated in FIG. 1. Thisallowed testing of the foam side of the specimens to indicate antimicrobial effect of the pad 12 without film 18 and testing of the film side to indicateantimicrobial effect of the pad 12 with film 18. The AATCC 174 test method provides for testing both unwashed and washed samples. Washed samples weretreated according to the AATCC 138 protocol. The test results are summarized as follows.

The AATCC 174 test method includes three parts. Part I is a qualitative test for antibacterial activity. Test specimens are placed into contact with a nutrientagar which has been streaked with a bacterial culture. The specimens are then incubated. After incubation, a clear area of interrupted growth underneath andalong the sides of the test specimen indicates antibacterial activity of the specimen. Standard strains of bacteria are used, with Staphylococcus aureus andKlebsiella pneumoniae being the representative organisms.

In the AATCC 174, Part I tests various washed and unwashed specimens were tested. An unwashed foam side specimen with 751 ppm of zinc pyrithionepassed the test with a one millimeter zone of inhibition for Klebsiella pneumoniae and a two millimeter zone of inhibition for Staphylococcus aureus. All


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unwashed and washed foam side specimens with a concentration of 1096 ppm or more of zinc pyrithione inhibited the growth of Klebsiella pneumoniae fromunderneath and along the sides of the specimen.

The AATCC 174, Part II test provides a quantitative procedure for the evaluation of the degree of antibacterial activity. Test specimens are inoculated with thetest microorganisms. After incubation, the bacteria are eluted from specimens by shaking in 100 milliliters of liquid. The number of bacteria present in the liquidis determined and the percent reduction produced by the specimen is calculated.

In the AATCC 174, Part II tests, washed foam side specimens containing 751 and 1096 ppm of zinc pyrithione provided a 90% reduction in the numbers ofboth Staphylococcus aureus and Klebsiella pneumoniae. In all unwashed and washed film and foam side specimens containing a concentration of 500 ppm ormore of zinc pyrithione in the film and 1096 ppm of zinc pyrithione in the pad, there was a reduction of at least 66% in Staphylococcus aureus with an averagereduction of 92%.

The AATCC 174, Part III protocol provides a qualitative test for antifungal activity. Specimens are subjected to the growth of a common fungus, Aspergillusniger, on Sabouraud Dextrose agar. Prewet specimens are inoculated and incubated at 28 degrees C. for seven days. Specimens are then assessed for growth ofthe fungus.

In the AATCC 174, Part III tests, washed and unwashed foam side samples with a concentration of 1096 ppm of zinc pyrithione in the pad produced noobservable fungus growth. No growth was observed on washed and unwashed film side samples when the concentration of zinc pyrithione in the film was 1500ppm or greater.

Inhibitory mold activity was also tested by the ASTM E2180-01 test method. Good inhibitory activity for Aspergillus niger was observed when film sidespecimens had a total minimum combined concentration of 1600 ppm of zinc pyrithione. The total combined concentration is the sum of the concentration inthe pad 12 of a specimen and the concentration in the film 18 of the specimen. The tests indicate that a minimum of 500 ppm may be preferred in the film 18,with a preferred complement minimum of 1100 ppm in the pad 12. Alternatively, a minimum concentration of 750 ppm may be preferred in the pad 12 with apreferred complement minimum of 850 ppm in the film 18. Good results were achieved for some, but not all, specimens with a total combined concentration of1251 ppm, i.e. 751 ppm in the pad 12 and 500 ppm in the film 18. Therefore, the preferred minimum combined concentration is about 1600 ppm.

Mold susceptibility tests were also performed under the ASTM D3273 test method. No Aspergillus niger mold colonization was observed on film 18 sidespecimens when the specimens had a total minimum combined concentration of about 1600 ppm zinc pyrithione. The tests indicate that a minimum of 500 ppmmay be preferred in the film 18, with a preferred complement minimum of 1100 ppm in the pad 12. Alternatively, a minimum concentration of 750 ppm may bepreferred in the pad 12 with a preferred complement minimum of 850 ppm in the film 18.

The above described tests indicate that an effective antimicrobial carpet underlay 10 can be made by incorporating 7500 to 12500 ppm of zinc pyrithione intobinder used to bind foam particles to make rebond ed carpet pad. The net concentration in the foam pad 12 is from 750 to 1250 ppm of zinc pyrithione whenthe binder to foam weight is 1:10. If different ratios of binder to foam are used, it is preferred to adjust the concentration in the binder stream to achieve at leastabout 750 ppm of zinc pyrithione in the final foam pad 12.

The tests also indicate that an effective antimicrobial film can be made by incorporating 500 to 1500 ppm of zinc pyrithione in the film 18. As noted above, theinitial concentration is preferably adjusted to account for thermal degradation which occurs during film processing. Thus, the initial ten percent concentration ofzinc pyrithione in the resin concentrate may be reduced to an effective five to six percent after processing.

The tests also show that when both a foam pad 12 and a film 18 including a biocide are combined to form a carpet underlay, lower concentrations of zincpyrithione may be used than may be necessary if only the pad 12 or the film 18 contains the biocide. In general, in a carpet underlay having a biocide treatedpad 12, but an untreated film 18, the pad 12 preferably has a biocide concentration near the upper end of the range tested, e.g. at least about 1100 to 1250 ppmof zinc pyrithione. For an underlay having an untreated pad 12, and a treated film 18, the film 18 preferably has a biocide concentration near the upper end ofthe range tested, e.g. at least about 1100 to 1500 ppm of zinc pyrithione. When both the pad 12 and film 18 are treated, it is preferred that the combinedconcentrations for foam pad 12 and film 18 be at least about 1600 ppm.

In the above disclosure, the concentrations of biocide in the foam pad 12 and film 18 have been discussed in terms of ranges having a lower limit and an upperlimit. It is apparent that it is preferred to include concentrations at or above the lower limits to achieve an effective antimicrobial activity in the products. Thatis, concentrations above the ranges tested should also be effective. Concentrations should be kept below a level at which the biocide may affect the mechanicalintegrity of the product. Since the biocide is a relatively high cost part of the product, normal practice should be to avoid using more of the biocide than isneeded to achieve effective biocidal or antimicrobial activity.

The particular choice of an effective amount of the biocide also depends upon the particular application in which the carpet pad will be used. In someapplications, there is a requirement that carpet products exhibit effective antimicrobial activity after being washed. For those applications, it may be desirable touse a concentration at or near the upper limits of the ranges given above. In the tests reported above, the specimens at the upper ends of the ranges providedeffective antimicrobial activity after washing. If the application does not require washing, a lower concentration of biocide provides an effective biocidalactivity.

In the above description of making the rebond ed foam pad 12, zinc pyrithione was initially mixed in powder form with a polyol. The resulting mixture isbasically a suspension of particles in a liquid. As noted in the description of FIG. 2, it is desirable to continuously operate a mixer in run tank 24 to insure thatthe zinc pyrithione remains uniformly mixed with the polyol. It may be desirable to first dissolve the zinc pyrithione in a fluid which is miscible with a polyol.Such a process is described in U.S. Pat. No. 5,114,984 issued to Branch et al. on May 19, 1992. In that patent, a pyrithione salt is dissolved in an alkanolaminewhich is miscible with a polyol, which the Branch patent indicates may then be used to make an antimicrobially effective polyurethane. Such a solution of zincpyrithione in polyol may also be suitable for mixing with the binder described above for use in the present invention.

While the present invention has been disclosed in terms of specific structures, chemical compositions and mixtures, and methods of making carpet underlay, itis apparent that various changes and substitutions of materials and steps may be made within the scope of the present invention as defined by the appendedclaims.

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Rebond polyurethane foams can be prepared bycoating shredded polyurethane foam with aprepolymer binder formulation which includes toluenediisocyanate distillation bottoms, compressing thebinder coated foam, and the curing the binder withsteam. The toluene diisocyanate distillation bottomscan be used in place of more expensive prepolymerformulation components such as toluene diisocyanateor methylene diphenyldiisocyanate. The toluenediisocyanate distillation bottoms can also improveelongation and tear resistance properties of theresultant rebond foams prepared therewith.

5312888 PDF help

Title:Flexible polyurethane rebond foam having improved tear resistance and method for the preparation thereofDocument Type and Number:United States Patent 5312888Abstract:

Inventors:Nafziger, John L. (Lake Jackson, TX)Lowenkron, Steven B. (Houston, TX)Koehler, Charles E. (Baytown, TX)Stevens, Bruce N. (Longview, TX)Application Number:08/148471Publication Date:05/17/1994Filing Date:11/08/1993View Patent Images:


Export Citation:Click for automatic bibliography generationAssignee:The Dow Chemical Company (Midland, MI)Primary Class:528/67Other Classes:521/54International Classes:C08G18/10; C08G18/72; C08J9/33; C08G18/00; C08J9/00; C08G18/70Field of Search:528/67, 521/54US Patent References:3256218Dispersing coarse fillers in polyurethane foams June, 1966 Knox 521/54

3894973Use of pneumacel in rebonded structurescomprising polyurethane scrap July, 1975 Yunan 521/137

4014826Process for preparing rebonded foam structuresMarch, 1977Yunan 521/54

4385131Polyurethane foam resistant to smolderingcombustion containing either urea or melamine May, 1983 Fracalossi521/55

4683246Polyurethane foam-fiber composites July, 1987 Davis 521/137Other References:"Recyclin of Thermoset Polyurethane Elastomers" by Henri Ulrich, et al. in Journal of Elastomers and Plastics, vol. 11, pp. 208-212 (1979)."Recycling of RIM Polyurea Elastomers by Thermal Processing" by Sachchida N. Singh, et al. Int'l Congress & Expo, Detroit, Mich., Feb. 25-Mar. 1, 1991 in SAE Technical Paper Series 910582."Recycling of RIM Scrap by Compression Molding" by Ronald P. Taylor, et al. Int'l Congress & Expo, Detroit, Mich., Feb. 25-Mar. 1, 1991 in SAE Technical Paper Series 910581."Recycling of Thermoset Polyurethane Elastomers" by Henri Ulrich, et al. in Journal of Elastomers and Plastics, vol. 11, pp. 208-212 (1979)."Alcoholysis-a Process for Chemically Recycling PUR and Mixed Plastic Wastes" by Aalen Bauer in Kunststoffe 81 (1991) 4, pp. 30-305."Recycling Flexible Foam: A Novel Technology Produces a Quality Product with Improved Economics" by B. D. Bauman, et al., Air Products & Chemicals, Inc. 1983, pp. 139-141.Primary Examiner:Foelak, MortonParent Case Data:CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 07/989,256 filed Dec. 11, 1992.

Claims:What is claimed is:

1. An isocyanate prepolymer formulation useful for preparing a binder comprising:

(A) methylene diphenyldiisocyanate or polymethylene polyphenyl polyisocyanate;

Flexible polyurethane rebond foam having improved tear resistance and m... http://www.freepatentsonline.com/5312888.html?query=PN/5312888%...

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(B) toluene diisocyanate distillation bottoms; and

(C) an active hydrogen containing material.

2. The formulation of claim 1 wherein the formulation additionally includes toluene diisocyanate.

3. The formulation of claim 1 wherein the active hydrogen containing material is difunctional.

4. The formulation of claim 1 wherein the toluene diisocyanate bottoms contain from about 5 to about 40 percent toluene diisocyanate monomer.

5. The formulation of claim 4 wherein the toluene diisocyanate bottoms contain from about 20 to about 30 percent toluene diisocyanate monomer.

6. The formulation of claim 4 wherein the weight percent of toluene diisocyanate bottoms is from about 10 to about 50 percent of the total weight of isocyanate group containing materials.

7. The formulation of claim 6 wherein the weight percent of toluene diisocyanate bottoms is from about 15 to about 30 percent of the total weight of isocyanate group containing materials.

8. The formulation of claim 1 wherein the active hydrogen containing material is a base polyol.

Description:

BACKGROUND OF THE INVENTION

The present invention relates to compositions of rebond foam. The present invention particularly relates to flexible polyurethane rebond foam compositions.

Polymer foams, particularly flexible polymer foams, can be fabricated into objects having useful shapes. For example, flexible foams can be molded or machined into shapes useful for preparingautomobile seats, bedding, and the like. Flexible foams can be used in carpet and furniture production as well as in the manufacture of toys and the like.

However, in processes for preparing shaped polymer foams, waste foam can be produced. The waste foam can be from the fabricating process and represent the area/volume of the foam removedfrom the starting block stock to form the shaped foam object. Or, the waste foam can be just the off-specification products which are occasionally produced in some fabricating processes.

Whatever its source, waste foam production is usually undesirable. The waste foam can represent materials which must be discarded and not sold. In some areas, landfill space has become scarceand the cost of disposing of waste foam has become very high.

There have been efforts to re-use waste foam production, particularly waste and scrap from the production of flexible foams. Flexible polyurethane foam scrap can be chopped and then coated witha binder consisting of a polyisocyanate prepolymer having isocyanate functionality, and a catalyst. The coated, chopped foam is compressed and then treated with steam to cure the binder to form arebond foam sheet or other shape.

In another process for using flexible polyurethane foam waste, the flexible foam waste is cryogenically ground and blended back into the formulation used to prepare it. The ground flexible foamcan be used at a level of about 20 percent within the polyol component of the polyurethane foam formulation.

However, preparing materials including waste foam is not always trouble free. The resultant materials may have inferior physical properties. Or the materials so produced can have imperfect finisheswhich will not permit its use in external and visible applications.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a method for preparing a flexible polyurethane rebond foam comprising a first step of applying a binder prepared from a formulation including (A) methylenediphenyldiisocyanate or polymethylene polyphenyl polyisocyanate; (B) toluene diisocyanate distillation bottoms; and (C) an active hydrogen containing material; to a shredded flexible polyurethanefoam and a second step of compressing the coated foam in the presence of steam for a period of time sufficient to bind the shredded foam.

In another aspect, the present invention is a flexible polyurethane foam comprising a foam prepared by a two step method having a first step of admixing shredded flexible polyurethane foam and abinder prepared from a formulation including (A) methylene diphenyldiisocyanate or polymethylene polyphenyl polyisocyanate; (B) toluene diisocyanate distillation bottoms; and (C) an activehydrogen containing material; and a second step of compressing the coated foam in the presence of steam for a period of time sufficient to bind the shredded foam.

In yet another aspect, the present invention is an isocyanate prepolymer formulation useful as a binder comprising (A) methylene diphenyldiisocyanate or polymethylene polyphenyl polyisocyanate;(B) toluene diisocyanate distillation bottoms; and (C) an active hydrogen containing material.

Another aspect the present invention is, in a method of preparing a flexible rebond polyurethane foam by coating shredded flexible polyurethane foam with a polyisocyanate prepolymer binder andcompressing the foam in the presence of steam to cure the binder, the improvement comprising preparing the binder from a formulation including toluene diisocyanate distillation bottoms.

The flexible polyurethane rebond foam of the present invention can have higher tear resistance and elongation than conventional rebond foam. Additionally, the rebond foams of the presentinvention are prepared with a binder formulation including toluene diisocyanate distillation bottoms, a material generally considered to be a waste material. Desirably, the TDI bottoms can be usedto replace more costly materials such as MDI and TDI found in conventional binders thereby reducing binder cost.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In one embodiment, the present invention is a method for preparing flexible polyurethane rebond foam. In this method, shredded flexible polyurethane foam is coated with a binder. The shreddedfoam can be of any size which is compatible with equipment available to coat the foam. However, preferably, the foam is shredded into pieces having dimensions of from about 0.1 to about 5 cm,more preferably of from about 0.25 to about 7.5 cm, and even more preferably of from about 0.63 to about 1.27 cm.

The binder of the present invention can be applied in any way known to those skilled in the art of preparing rebond foam to be useful for applying a binder to shredded foam. For example, if thebinder is merely sprayed upon bulk shredded foam, the shredded foam can be tumbled to insure a uniform coating of all surface areas of the foam. In the alternative, the foam can be suspended in acolumn of air and the binder applied either in a stream or as an aerosol. However the binder is applied, it is applied in an amount of at least 5 percent, preferably at least 7 percent, and even morepreferably at least 8 percent of the total weight of the shredded foam and binder prepolymer.

The binder of the present invention is prepared from a formulation including (A) methylene diphenyldiisocyanate (MDI) or polymethylene polyphenyl polyisocyanate (PMDI); (B) toluenediisocyanate distillation bottoms (TDI bottoms); (C) an active hydrogen containing material; and, optionally (D) toluene diisocyanate (TDI). The binder is, in fact, a prepolymer, with the admixtureretaining isocyanate functionality. The exact ratio of materials to be used to prepare the binder of the present invention will vary depending upon the desired properties of the binder. For example, ifa specific binder viscosity is desired, then the ratio of isocyanate and active hydrogen containing components will vary depending upon what materials are chosen for the binder formulation.

Generally, in the art of preparing prepolymers, the formulation for a prepolymer is determined based on the desired residual isocyanate group concentration. Care must be taken in preparingisocyanate prepolymers because if the ratio of equivalents of isocyanate groups to active hydrogen groups is too close to 1:1, a solid rather than a liquid can be formed. As a rule of thumb,prepolymers based on difunctional precursors should have a residual isocyanate group concentration of at least 2 percent. Prepolymers based on trifunctional precursors should have a residualisocyanate group concentration of at least 10 percent.

The amount active hydrogen group containing material and prepolymer required to prepare a prepolymer can be calculated using the formula:

Step I

A=NCO--eq. wt.+AH--eq. wt.

Step II


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B=42.02/NCO--eq. wt.

Step III

X=(Z(A+X))/B

wherein NCO--eq. wt. is the equivalent weight of the isocyanate component, AH--eq. wt. is the equivalent weight of the active hydrogen material, Z is the decimal percentage (i.e., 10 percent=0.1decimal percent) of residual isocyanate groups desired in the prepolymer, and X is the amount of isocyanate component to be added in excess of 1:1 stoichiometry to prepare a prepolymer having Zresidual isocyanate groups. For example, to prepare a prepolymer having 15 percent residual isocyanate groups from a 1,000 equivalent weight polyol and a 140 equivalent weight isocyanate:

A=140+1,000=1,140

B=42.02/140=0.3001

X=((0.15(1,140+X))/0.3001=1,392

1,392 parts plus 140 parts isocyanate would be required for each 1,000 parts polyol.

The binder formulation of the present invention includes both TDI bottoms and either MDI or PMDI. TDI bottoms are a byproduct of commercial TDI production. It is known to prepare toluenediisocyanates by the phosgenation of toluene diamine. Typical processes for the phosgenation of amines can be found in U.S. Pat. Nos. 2,680,127; 2,822,373 and 3,781,320. In the phosgenation oftoluene amines to form toluene diisocyanates, the product diisocyanate is generally distilled from the reaction mixture in which it is prepared. At the conclusion of the distillation, the reactionmixture normally contains a quantity of high boiling residue. Such residue generally comprises polymeric materials such as alpha, omega-isocyanatobiurets, polycarbodiimides, diisocyanatocarbodiimides, polyuretidinediones, isocyanurates and various other isocyanate adducts. Since this residue is seldom commercially useful, it is usually disposed of.

The TDI bottoms also contain some residual TDI monomer. Generally, the range of TDI monomer in TDI bottoms will vary from about 5 to 40 percent. However, for the purposes of the presentinvention, the TDI bottoms will preferably contain from about 20 to about 30 percent TDI monomer. The TDI bottoms can be as produced from the TDI production unit if they are sufficientlyreactive to form the prepolymer or they can be viscosity stabilized and/or higher reactivity TDI bottoms. For example, the TDI bottoms useful with the present invention can be those prepared bythe method of co-pending U.S. patent application Ser. No. 07/647,328 or by the method of U.S. Pat. No. 4,904,704.

The ratio of TDI bottoms to MDI or PMDI will vary with the desired viscosity of the prepolymer. However, for both economical and performance purposes, the prepolymer formulation will includeas much of the TDI bottoms as can be easily handled during production of the prepolymer. The TDI bottoms, normally considered a waste or low value product, can be used with the presentinvention in place of some of the MDI or TDI found in conventional formulations. The TDI bottoms serve to both increase elongation and tear resistance and to replace an expensive prepolymerformulation component with a less expensive prepolymer formulation component. Therefore, the weight percent of TDI bottoms of the total weight of isocyanate group containing materials can befrom about 1 to 99, but is preferably from about 10 to about 50, and even more preferably from about 15 to about 30.

MDI and PMDI are commercially prepared by the phosgenation of mixtures of the methylene dianiline and corresponding methylene-bridged polyphenyl polyamines. PMDI contains from about 20to about 85, preferably from about 30 to about 75, percent by weight of MDI; about 3 percent to about 30 percent byproducts and impurities; and the remainder closely related polyisocyanates ofhigher molecular weight and functionality greater than about 2. TDI can be used in place of part of the MDI or PMDI, but use of TDI can decrease the improved physical properties of the presentinvention. Use of TDI also can cause a two phase system in preparing the prepolymer which could increase handling problems. Therefore, TDI, when it is used in the prepolymer binder formulationis preferably present at less than about 70 weight percent of the isocyanate group containing component.

The active hydrogen containing materials useful with the present invention are preferably any which can be used to prepare a flexible isocyanate based foam. Active hydrogen containingcompounds most commonly used in polyurethane production are those compounds having at least two hydroxyl groups. Those compounds are referred to herein as polyols. Representatives ofsuitable polyols are generally known and are described in such publications as High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology" by Saunders and Frisch, IntersciencePublishers, New York, Vol. I, pp. 32-42, 44-54 (1962) and Vol. II, pp. 5-6, 198-199 (1964); Organic Polymer Chemistry by K. J. Saunders, Chapman and Hall, London, pp. 323-325 (1973); andDevelopments in Polyurethanes, Vol. I, J. M. Burst, ed., Applied Science Publishers, pp. 1-76 (1978).

Any active hydrogen containing compound can be used with the method of this invention. Examples of such materials include those selected from the following classes of compositions, alone or inadmixture: (a) alkylene oxide adducts of polyhydroxyalkanes; (b) alkylene oxide adducts of non-reducing sugars and sugar derivatives; (c) alkylene oxide adducts of phosphorus and polyphosphorusacids; and (d) alkylene oxide adducts of polyphenols. Polyols of these types are referred to herein as "base polyols".

Examples of alkylene oxide adducts of polyhydroxyalkanes useful herein are adducts of ethylene glycol, propylene glycol, 1,3-dihydroxypropane, 1,4-dihydroxybutane, and 1,6-dihydroxyhexane,glycerol, 1,2,4-trihydroxybutane, 1,2,6-trihydroxyhexane, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, pentaerythritol, polycaprolactone, xylitol, arabitol, sorbitol, mannitol, and the like.Preferred herein as alkylene oxide adducts of polyhydroxyalkanes are the ethylene oxide adducts of trihydroxyalkanes. Other useful adducts include ethylene diamine, glycerin, ammonia, 1,2,3,4-tetrahydroxy butane, fructose, and sucrose.

Also useful with the present invention are poly(oxypropylene) glycols, triols, tetrols and hexols and any of these that are capped with ethylene oxide. These polyols also includepoly(oxypropyleneoxyethylene)polyols. The oxyethylene content should preferably comprise less than about 80 weight percent of the total and more preferably less than about 40 weight percent.The ethylene oxide, when used, can be incorporated in any way along the polymer chain, for example, as internal blocks, terminal blocks, or randomly distributed blocks, or any combinationthereof.

Polyamines, amine-terminated polyols, polymercaptans and other isocyanate-reactive compounds are also suitable in the present invention. Polyisocyanate polyaddition active hydrogen containingcompounds (PIPA) are use with the present invention. PIPA compounds are typically the reaction products of TDI and triethanolamine. A method for preparing PIPA compounds can be found in,for example, U.S. Pat. No. 4,374,209, issued to Rowlands.

Another class of polyols useful with the present invention are "copolymer polyols", which are base polyols containing stably dispersed polymers such as acrylonitrile-styrene copolymers. Productionof these copolymer polyols can be from reaction mixtures comprising a variety of other materials, including, for example, catalysts such as azobisisobutyronitrile; copolymer polyol stabilizers; andchain transfer agents such as isopropanol.

Yet another class of useful polyols are the polyester polyols. Particularly polyester polyols having difunctionality are useful with the present invention. Examples of useful polyester polyols include,for example, polybutanediol adipate and poly -caprolactone.

The polyols, polyamines and other active hydrogen containing materials of the present invention are preferably those which could be used to prepare a flexible isocyanate based foam. Suchpolymers generally have a molecular weight of from about 1,000 to about 10,000, preferably from about 2,500 to about 5,000 and most preferably from about 3,000 to about 4,000. If the activehydrogen containing material is a polyether, preferably it is a polyoxyalkylene polyether polyol wherein the oxides are propylene oxide and ethylene oxide and the ratio of propylene oxide toethylene oxide is from about 20:1 to 2:1. Preferably, the nominal functionality of the active hydrogen containing materials of the present invention is from 2 to 4 and more preferably from 2 to 3.

The MDI or PMDI, TDI bottoms and active hydrogen containing material are admixed to prepare a prepolymer which can be used as a binder for shredded polyurethane foam. Any method knownto those skilled in the art of preparing polyurethane prepolymers to be useful can be used to prepare the prepolymer of the present invention. Generally, the prepolymer can be prepared by admixingthe formulation and stirring it at ambient temperature for a convenient period, for example, overnight. Alternatively, the admixture can be heated to about 55 C. and stirred for about 1 hour.Preferably, the admixture is stirred at ambient conditions overnight under an inert gas pad. Stirring should continue until most of the active hydrogens have reacted with the isocyanate groups. Afterthe prepolymer is prepared, it can be applied to shredded polyurethane foam.

In addition to shredded polyurethane foam, the prepolymer of the present invention can be used to bind other materials or mixtures of polyurethane foam and other materials. The present inventionis particularly useful for binding materials having isocyanate reactive moieties. For example, the present invention can be used to bind wood, paper, and inorganic materials such as sand, and thelike. A matrix consisting of paper and shredded foam can be prepared by the method of the present invention. Flexible foam containing urea groups, thiourethane groups, and the like, in addition toor in place of polyurethane groups, can be used to prepare rebond foam pads by the method of the present invention. Unusual or specialty polyurethane foams can also be used with the presentinvention. For example, filled foams can be used with the present invention.

Rebond foam is known to be useful for several purposes. The rebond foam of the present invention can be used for such applications as packing foam, filler for structural voids, absorbent mediumand the like. The rebond foams of the present invention, due to their superior properties and low cost, are particularly useful in carpet pad applications.

The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the present invention and they should not be so interpreted. Amounts are


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in weight parts or weight percentages unless otherwise indicated.

EXAMPLE 1

A high reactivity TDI bottoms is prepared by heating 27.9 lb (12.65 kg) of TDI bottoms having about 25 percent free TDI to about 360 F. (183 C.) and admixing with a diglycidyl ether ofbisphenol A having an epoxy equivalent weight of about 181 by slowly pumping the epoxy material into the TDI bottoms with constant stirring over a period of about 30 minutes. After the last ofthe epoxy material is added, the TDI bottoms and epoxy admixture is quickly cooled to about 122 F. (50 C.) and stored for three days. After the three day storage period, 18 parts of TDI bottomsepoxy admixture is further admixed with 82 parts PMDI having a viscosity of about of about 42 cps (0.042 Ps s) to produce a TDI bottoms-PMDI solution having a viscosity of 200 cps (0.2 Pa s)and an isocyanate equivalent weight of 137, referred to hereinafter as "TBPP".

A prepolymer is prepared by admixing 253.8 parts TBPP and 200 parts of a mixed propylene oxide and ethylene oxide polyether polyol having a nominal functionality of 3 and a molecular weightof about 3,500. The polyol and TBPP are admixed and stirred overnight under a nitrogen pad. The resultant prepolymer has a residual isocyanate group concentration of 15.5 percent.

A rebond foam pad is prepared by placing 138.5 g scrap flexible polyurethane foam with dimensions of from about 1.0 to about 2.5 cm into a drum and then adding 12.85 grams prepolymer to thedrum. The drum is rotated for 5 minutes at 60 to 100 rpm. The prepolymer coated foam is removed from the drum and placed between 12.25 in (31.2 cm)12.25 in (31.2 cm) perforated plates,compressed to thickness of 1 inch (2.54 cm) and exposed to steam for five minutes. The resulting rebond foam pad is removed from the plates, dried at ambient conditions for one week, and testedfor physical properties. The physical properties are reported in the table below.

EXAMPLE 2

A rebond foam pad is prepared and tested substantially identically to that of Example 1 except that the prepolymer is prepared from a formulation including 165.63 parts of TBPP, 41.41 parts ofTDI, and 200 parts of a mixed propylene oxide and ethylene oxide polyether polyol having a nominal functionality of 3 and a molecular weight of about 3,500. The physical properties are reportedin the table below.

COMPARATIVE EXAMPLE 3

A rebond foam pad is prepared and tested substantially identically to that of Example 1 except that the prepolymer is prepared from a formulation including 56.0 parts PMDI having a nominalviscosity of 200 cps (0.200 Pa s) and 200 parts of a mixed propylene oxide and ethylene oxide polyether polyol having a nominal functionality of 3 and a molecular weight of about 3,500. Thephysical properties are reported in the table below.


A rebond foam pad is prepared and tested substantially identically to that of Example 1 except that the prepolymer is prepared from a formulation including 56.0 parts PMDI having a nominalviscosity of 200 cps (0.200 Pa s), 10.2 parts TDI and 200 parts of a mixed propylene oxide and ethylene oxide polyether polyol having a nominal functionality of 3 and a molecular weight of about3,500. The physical properties are reported in the table below.


A rebond foam pad is prepared and tested substantially identically to that of Example 1 except that the prepolymer is prepared from a formulation including 38.0 parts TDI and 200 parts of a mixedpropylene oxide and ethylene oxide polyether polyol having a nominal functionality of 3 and a molecular weight of about 3,500. The physical properties are reported in the table below.

TABLE________________________________________________________ __________________COMP. COMP. COMP. EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE 1 2 3* 4* 5*________________________________________________________ __________________

DENSITY 13.87 3.93 3.88 3.79 3.79lb/ft 3(62.00)(62.90)(62.15)(60.71)(60.71)(kg/m 3 )ELONG- 47 52 19 25 41ATION 2 %TEAR 0.63 0.57 0.50 0.50 0.60RESIS- (4.34) (3.93) (3.45) (3.45) (4.14)TANCE 3psi(kPa)________________________________________________________ __________________

*Not an example of the present invention. 1 ASTM D 357491 Standard Test for Flexible Cellular Materials Slab, Bonded, and Molded Urethane Foams; Test A 2 Id., Test E 3 Id., Test F

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A process of preparing rebonded structures from acomposition which includes both particulateelastomeric foam and pneumacel fibers.

4014826 PDF help

Title:Process for preparing rebonded foam structuresDocument Type and Number:United States Patent 4014826Abstract:

Inventors:Yunan, Malak E. (Boonton Township, NJ)Application Number:

05/558020Publication Date:03/29/1977Filing Date:03/13/1975View Patent Images:


Export Citation:Click for automatic bibliography generationAssignee:E. I. Du Pont de Nemours and Company (Wilmington, DE)Primary Class:521/54Other Classes:264/DIG.007International Classes:B29B17/00; B29C67/20; C08J9/33; C08J9/00; C08J9/22; C08G18/14Field of Search:260/2.5AK, 260/2.5BE, 260/2.5B, 260/2.5H, 260/2.5HA, 260/2.5HB, 260/2.5F, 260/2.5NUS Patent References:

3114722Preparation of a composition containing expandedpolymeric materials December, 1963Einhorn et al.260/2.5AK

3227664Ultramicrocellular structures of crystallineorganic polymer January, 1966 Blades et al. 264/118

3256218Dispersing coarse fillers in polyurethane foams June, 1966 Knox 260/2.5AK

3401128Polyurethane foam product and method of makingsame September, 1968Terry 260/2.5AK

3582500 June, 1971 Carriere et al.260/2.5BEForeign References:UK997334 July, 1965 260/2.5AKPrimary Examiner:Cockeram H. S.Parent Case Data:CROSS-REFERENCE TO RELATED APPLICATION

This is a division of my copending application Ser. No. 452,568, filed Mar. 19, 1974 now U.S. Pat. No. 3,894,973.

Claims:Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. The process of preparing a molded cushioning structure which comprises the steps of:

a. shredding or otherwise subdividing pneumacel batting into particles of substantially single-fiber dimensions,

b. mixing 1-50 parts by weight of the subdivided pneumacel batting of step (a) with 99-50 parts by weight of shredded elastomeric foam,

c. wetting the resulting mixture with from 5-50 parts by weight of elastomeric binder progenitor, and

d. curing the mixture resulting from steps (a) through (c) under conditions which result in conversion of the progenitor into an elastomeric adhesive, thereby bonding the mixture into a unitaryelastomeric structure.

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Description:

BACKGROUND OF THE INVENTION

In the manufacture of cushioning structures of elastomeric foam, a syrup or compounded latex comprising the elastomeric-foam progenitors is cured in a mold under conditions which result in"blowing" and curing. Subsequent cutting into the various shapes and sizes required results in the formation of scrap, i.e., pieces too small to have utility per se. It is known to recover such scrap byshredding, wetting with a fluid curable to an elastomeric binder, and remolding the mass under conditions to cure the binder to yield a unitary foam structure which has useful properties, albeitsomewhat different from those of the original foam.

Typical of the prior art are U.S. Pat. Nos. 3,114,722, 3,300,421 and 3,401,128. Essentially these describe coating comminuted polyurethane foam particles with a bonding agent comprising aprepolymer of polyurethane -- the reaction product of a polyhydroxy compound with a polyisocyanate -- and hastening the bonding process by placing the shredded polyurethane foam andprepolymer in a mold, wherein the prepolymer forms a coating around the particles of shredded material, applying heat and pressure, and recovering a molded article. Such a product is commonlyreferred to as a "rebonded" structure. It is improved in load-support characteristics over the original, which the cushioning trade regards as a substantial advantage; but it is somewhat higher indensity than the original foam from which the shreds were obtained. This is a disadvantage. It still resembles the original (e.g., polyurethane) foam, however, in that although capable of bearing asomewhat greater load at a given degree of compression, it will, nonetheless, "bottom out" with moderate further loading, thus losing its cushioning characteristics.

Cushioning structures are also prepared from very low density cellular fibers which have excellent pneumatic properties. In general, these so-called pneumacel fibers are made from syntheticorganic polymers and are composed predominately of small, polyhedral-shaped, closed cells, the cells being defined by thin, film-like walls of polymer. Gases contained within the cells contribute tothe stiffness and pneumatic behavior of the cellular fibers. Such fibers have densities of 0.01 g./cc. or less and, due to their pressurized, pneumatic character, are noncompliant, "springy" structures.If held under compression, pneumacel will lose part of its trapped gas, but when the pressure is released it will reabsorb air and reinflate to its original size.

These fibers, in batt form, are useful as cushioning layers in mattresses, auto upholstery, or upholstered furniture for thermal insulation, or for carpet cushion underlays. Such batts are formedtypically by depositing the fibers as a loose uniform batt on a continuous belt, impregnating them with a thermoplastic binder in the form of a latex, drying, heating to activate the binder,compression, and cooling before release from compression to set the batt in its compressed form. Other additives such as fire-retardants, dyes, etc. may also be applied to the batting. Some of thenumerous patents on this general subject are U.S. Pat. Nos. 3,375,211; 3,375,212; 3,503,907; 3,485,711; 3,535,181; 3,743,694; 3,717,904 and 3,730,916.

Suitable pneumacel fibers are prepared from synthetic crystallizable, organic polymers, and as described in U.S. Pat No. 3,227,664, include polyhydrocarbons such as linear polyethylene,stereoregular polypropylene or polystyrene; polyethers such as polyformaldehyde; vinyl polymers such as poly(vinylidene fluoride); polyamides, both aliphatic and aromatic, such aspoly(hexamethylene adipamide) and poly(metaphenylene adipamide) and poly(metaphenylene isophthalamide); polyurethanes, both aliphatic and aromatic, such as the polymer from ethylenebischloroformate and ethylene diamine; polyesters such as poly(hydroxypivalic acid) and poly(ethylene terephthalate); copolymers such as poly(ethylene terephthalate isophthalate), and the like.The polymers are of at least film-forming molecular weight. Preferably, the pneumacel fibers are made of poly(ethylene terephthalate), inflated with Freon.

The processing of pneumacel batting, manufactured as described above, into cushioning structures of the desired shapes and sizes usually requires trimming off edges, corners and the like, whichtrimmings are hereafter referred to as scrap pneumacel batting.

SUMMARY OF THE INVENTION

It has now been found that rebonded structures of polyurethane foam can be upgraded considerably by the addition of pneumacel fibers to the molding composition. More particularly, the instantprocess is directed to the steps of (1) shredding or otherwise subdividing pneumacel batting into substantially single-fiber dimensions, (2) mixing from 1-50 parts by weight of such fibers with 99-50parts by weight of shredded elastomeric foam, for example polyurethane foam, (3) wetting the mixture with 5-50 parts by weight of elastomeric binder progenitor, and (4) curing the mixture underconditions which result in conversion of the progenitor into an adhesive, thereby bonding the mixture into a unitary, elastomeric structure.

The process is particularly advantageous insofar as it provides a practical utility for scrap pneumacel batting as well as for scrap foam. A surprising feature is that incorporation of pneumacel fibersinto the process for manufacture of "rebond" elastomeric foam within the above-stated limits results not only in a desirable decrease in density of the structure, but also in a product of improvedcushioning characteristics. In other words, the final product is improved over that without pneumacel both in load-to-compress and density. Pneumacel will not "bottom out" under a reasonable loadsuch as encountered in mattress padding and carpet backing, whereas polyurethane foams will. It has been recognized that rebond foam is firmer than the original foam from which the scrap isderived. Since a firmer texture is highly desirable for certain luxury cushioning, the still greater firmness with pneumacel fibers within the prescribed limits materially increases the value of thecushioning. The product feels like dense rubber and has a soft "hand." Incorporation of less than the prescribed amount of pneumacel results in no appreciable increase in firmness. Use of more thanthe prescribed amount leads to excessive firmness and limited utility for the composite structure.

The invention will readily be understood by reference to the following Examples, in which parts are by weight, and which are illustrative of the general procedure of this invention.

EXAMPLE I

About 6.4 g. of polyurethane foam sheets are cut into approximately one quarter inch cubes. About 6.4 g. of pneumacel sheet is shredded into essentially separate fibers having a length of one halfinch or less. The two particulate materials are slurried in a neoprene latex which has been diluted with water to 10% solids content. The latex is drained away; the wet mixture is then squeezedgently to remove excess latex, and dumped into a foraminous mold which is 12 inches in both horizontal dimensions and 1 inch high. The mold is closed, placed in an oven maintained at 120 C. for2 hours, removed and allowed to cool. The resulting one inch thick composite cushion comprises 2 oz. per square yard of both pneumacel and polyurethane chips and 3 oz. per square yard ofneoprene binder. It is useful as cushioning over springs.

EXAMPLE II

Polyurethane foam segments having a density of about 0.03 g./cc. were shredded to a particle-size average of about 0.3 cm. Likewise, segments of a pneumacel batt poly(ethylene terephthalate)were shredded to substantially single filaments, averaging about 0.3 cm. in length. Eighty-five parts of the polyurethane foam segments and 15 parts of the pneumacel fibers were mixed thoroughly,wetted by 10 parts of a polyurethane binder progenitor, specifically a polyurethane syrup containing no blowing agent, and pressed into a batch mold. The mold and contents were heated by steamto cure the binder and then cooled.

A comparison cushion was prepared in the same way except that 100 parts of the polyurethane shreds and no pneumacel fibers were used. The pneumacel composite cushion had a density of 3.3lb./ft. 3 vs. 6.0 lb./ft. 3 for the all-polyurethane comparison cushion. In a test designed to compare firmness, or resistance to bottoming under load, the ratios of loads supported at 65% and 25%compression were determined for the two cushions. The pneumacel composite had a ratio of 7.2, while the allpolyurethane comparison had a ratio of 5.2.

While illustrated only as applied to preparation of rebond composites of pneumacel and polyurethane foam, the invention is equally applicable to the preparation of rebond composite structurescomprising pneumacel with other shredded foams such as neoprene, natural rubber, and synthetic rubber.

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A layered cushioned composite such as a carpet orcarpet tile which in one embodiment incorporates alayer of stabilizing material and a layer of adhesivematerial below a primary carpet and above a layer ofcompressed particle, recycled and/or rebond foam orcushioning material.

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Title:Textile product and methodDocument Type and Number:United States Patent Application 20020132085

Kind Code:A1Abstract:

Inventors:Higgins, Kenneth B. (LaGrange, GA, US)Tippett, William (Lancashire, GB)Miller, Scott C. (LaGrange, GA, US)Application Number:09/993158

Publication Date:09/19/2002Filing Date:11/16/2001View Patent Images:


Export Citation:Click for automatic bibliography generationPrimary Class:428/95Other Classes:428/96, 428/317.900, 428/97International Classes:(IPC1-7): B32B005/22; B32B003/02; B32B033/00Attorney, Agent or Firm:Milliken & Company (P.O. Box 1926, Spartanburg, SC, 29304, US)Claims:

What we claim is:

1. A surface covering such as a wall covering, floor covering, carpeting, or carpet tile, comprising: a primary carpet, and a rebond foam cushion fixed at a position below said primary carpet.

2. The invention as recited in claim 1, further comprising at least one adhesive layer of at least one adhesive material between said primary carpet and said rebond foam cushion.

3. The invention as recited in claim 1, further comprising a layer of reinforcing material disposed within a mass of adhesive material such that at least a portion of said mass of adhesive materialextends away from at least one side 5 of said layer of reinforcing material.

4. The invention as recited in claim 2, wherein the adhesive material comprises at least one of a thermoplastic and thermoset adhesive.

5. The invention as recited in claim 1, wherein the primary carpet is characterized by a face weight of about 12-60 oz/yd2.

6. The invention as recited in claim 1, wherein the surface covering has a plurality of corners wherein each of said corners has a cup of about {fraction (3/16)} or less and a curl of about {fraction(1/16)} or less.

7. The invention as recited in claim 2, wherein the adhesive layer is present at a level of less than or equal to about 100 oz/yd2.

8. The invention as recited in claim 2, wherein the adhesive layer is present at a level of about 36-90 oz/yd2.

9. The invention as recited in claim 1, wherein the rebond foam cushion is characterized by a density of about 25 lbs. per cubic foot or less.


Textile product and method - Patent Application 20020132085 http://www.freepatentsonline.com/y2002/0132085.html?query=09%2F99...

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11. The invention as recited in claim 1, wherein the rebond foam cushion is characterized by an uncompressed chip size of about 25 mm or less.

12. The invention as recited in claim 11, wherein the uncompressed chip size is about 12 mm or less.

13. The invention as recited in claim 11, wherein the uncompressed chip size is about 7 mm or less.

14. The invention as recited in claim 1, wherein the rebond foam is characterized by a binder quantity of about 25% or less.

15. The invention as recited in claim 14, wherein the binder content is about 15% 20 or less.

16. The invention as recited in claim 14, wherein the binder content is about 10% or less.

17. The invention as recited in claim 2, wherein the adhesive material comprises a hot melt adhesive.

18. The invention as recited in claim 1, wherein the primary carpet is characterized by a face weight of less than or equal to about 55 oz/yd2.

19. The invention as recited in claim 17, wherein the hot melt adhesive is present at a level of about 36-50 oz/yd2.

20. The invention as recited in claim 2, wherein the adhesive material comprises a polyolefin based thermoplastic hot melt adhesive.

21. The invention as recited in claim 1, wherein the primary carpet is at least one of a tufted, bonded, flocked, needle punched, and woven carpet.

22. The invention as recited in claim 1, wherein the rebond foam cushion is characterized by a thickness of about 25 mm or less.

23. The invention as recited in claim 22, wherein the foam thickness is about 12 mm or less.

24. The invention as recited in claim 22, wherein the foam thickness is about 4 mm or less.

25. The invention as recited in claim 2, wherein the adhesive material comprises a polyurethane thermoset adhesive.

26. The invention as recited in claim 1, wherein the rebond foam cushion includes a backing material bonded to one surface thereof.

27. The invention as recited in claim 1, wherein the primary carpet is a tufted carpet including pile yarn, primary backing, and a pre-coat adhesive.

28. The invention as recited in claim 1, wherein the primary carpet is a tufted carpet including pile yarn and a primary backing.

29. The invention as recited in claim 1, wherein the primary carpet is a bonded carpet including pile yarn a n d a backing material.

30. The invention as recited in claim 3, wherein said layer of reinforcing material comprises at least one of a porous scrim, woven, and non-woven material.

31. The invention as recited in claim 3, wherein said reinforcement material is formed of fiberglass.

32. The invention as recited in claim 3, wherein said reinforcement material comprises a porous textile structure.

33. The invention as recited in claim 3, wherein said reinforcement material consists essentially of polyester.

34. The invention as recited in claim 3, wherein said layer of reinforcing material comprises a plurality of glass fibers.

35. The invention as recited in claim 3, wherein said layer of reinforcing material comprises a plurality of polyester fibers.

36. The invention as recited in claim 3, wherein said mass of adhesive material substantially permeates and covers the layer of reinforcing material and extends in bonding relation between saidprimary carpet and said rebond foam cushion such that said primary carpet and said rebond foam cushion are adhesively bonded to one another by said mass of adhesive material.

37. The invention as recited in claim 3, wherein said primary carpet is a tufted carpet and wherein said mass of adhesive material extends between said rebond foam cushion and the underside ofsaid primary carpet.

38. The invention as recited in claim 3, wherein said primary carpet is a bonded carpet and wherein said mass of adhesive material extends between said rebond foam cushion and the underside ofsaid primary carpet fabric.

39. The invention as recited in claim 3, wherein said mass of adhesive material substantially permeates and covers the layer of reinforcing material and extends in bonding relation between saidprimary carpet and said rebond foam cushion such that said primary carpet and said rebond foam cushion are adhesively bonded to one another by said mass of adhesive material and wherein alayer of textile backing material is bonded to said rebond foam cushion across the surface of said rebond foam cushion facing away from said adhesive material.

40. The invention as recited in claim 1, wherein said rebond foam cushion is characterized by a density of about 6 to 12 lbs. per cubic foot.

41. A surface covering such as a wall covering, floor covering, carpeting, or carpet tile, comprising: a primary carpet, a polyurethane rebond foam cushion disposed at a position below said primarycarpet, a mass of adhesive material disposed in bonding relation between said primary carpet and said rebond foam cushion and a layer of reinforcing material disposed between said primary carpetand rebond foam cushion such that at least a portion of said mass of adhesive material extends away from at least one side of said layer of reinforcing material.


43. The invention as recited in claim 42, wherein the primary carpet is characterized by a face weight of less than or equal to about 45 oz/yd2.

44. The invention as recited in claim 41, wherein the adhesive material is selected from at least one of thermoplastic and thermoset adhesives.

45. The invention as recited in claim 41, wherein the surface covering is at least one of a carpet tile, attached cushion broadloom carpet, and roll product.

46. The invention as recited in claim 41, wherein the polyurethane rebond foam cushion comprises at most 25% polyurethane binder and at least 50% polyurethane foam chips.

47. The invention as recited in claim 41, wherein the polyurethane rebond foam cushion has a density of about 6 to 12 lb./cu. ft.

48. The invention as recited in claim 41, wherein the primary carpet is a tufted carpet including pile yarn and a primary backing.

49. The invention as recited in claim 41, wherein a textile backing material is disposed across the underside of said polyurethane rebond foam cushion.

50. A method of forming a surface covering such as a carpet tile or carpet composite comprising the steps of: bonding at least one layer of rebond foam to the underside of a primary carpet fabric.

51. The method as recited in claim 50, further comprising the steps of bonding a reinforcement material between said primary carpet and rebond foam layer.


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52. The method as recited in claim 50, wherein said rebond foam is bonded to said carpet by at least one adhesive.

53. The method as recited in claim 50, wherein said rebond foam is bonded to said carpet by lamination.

54. A surface covering produced by the method of claim 50.

55. A method of forming a cushion backed carpet composite comprising the steps of: bonding a layer of rebond foam to the base of a primary carpet fabric with a layer of reinforcement materialtherebetween.

56. The method as recited in claim 54, wherein said rebond foam is bonded to said primary carpet by at least one adhesive.

57. A carpet composite produced by the method according to claim 55.

58. A dimensionally stable cushioned carpet tile suitable for disposition as discrete modular units across a flooring surface, the carpet tile comprising: a primary carpet fabric having a pile side and aprimary base with a plurality of pile forming yarns projecting outwardly from the pile side; a rebond foam cushion layer disposed at a position below the primary carpet fabric; and a bridgingcomposite extending in bonding relation substantially between the primary base and an upper side of the rebond foam cushion layer wherein the bridging composite consists essentially of a layer ofstabilizing material having a first side and a second side, a first layer of at least one resilient adhesive extending away from the first side of the stabilizing material into contacting relation with theprimary base and a second layer of at least one resilient adhesive extending away from the second side of the layer of stabilizing material into contacting relation with the upper side of the rebondfoam cushion layer such that the layer of stabilizing material is bonded between the first and second layers of resilient adhesive at a position between the primary base and the rebond foam cushionlayer.

59. The invention as recited in claim 58, wherein the primary carpet fabric is a tufted carpet and wherein the primary base comprises a primary backing and a layer of adhesive pre-coat extendingacross the underside of the primary backing.

60. The invention as recited in claim 59, wherein the adhesive pre-coat comprises at least one of a latex and hot melt adhesive.

61. The invention as recited in claim 60, wherein the hot melt adhesive is bitumen based hot melt adhesive.

62. The invention as recited in claim 60, wherein the hot melt adhesive is a polyolefin based hot melt adhesive.

63. The invention as recited in claim 58, wherein the resilient adhesive is at least one of a thermoset and thermoplastic.

64. The invention as recited in claim 58, wherein the primary carpet fabric is a bonded carpet.

65. The invention as recited in claim 58, wherein the rebond foam cushion layer comprises polyurethane rebond foam characterized by a density of about 5 to 25 lbs. per cubic foot.

66. The invention as recited in claim 58, wherein the rebond foam cushion layer comprises polyurethane rebond foam characterized by a density of about 5 to 12 lbs. per cubic foot.

67. The invention as recited in claim 58, wherein the first layer of at least one resilient adhesive comprises a thermoplastic adhesive.

68. The invention as recited in claim 67, wherein said adhesive is bitumen based hot melt adhesive.

69. The invention as recited in claim 67, wherein said adhesive is a polyolefin based hot melt adhesive.

70. The invention as recited in claim 67, wherein said first layer of resilient adhesive is a thermoset adhesive.

71. The invention as recited in claim 58, wherein the primary base comprises a primary backing and a layer of latex adhesive pre-coat extending across the underside of the primary backing.

72. The invention as recited in claim 58, wherein the primary base comprises a primary backing and a layer of hot melt adhesive pre-coat extending across the underside of the primary backing.

73. The invention as recited in claim 58, wherein the second layer of at least one resilient adhesive comprises a hot melt adhesive.

74. The invention as recited in claim 73, wherein said hot melt adhesive is bitumen based hot melt adhesive.

75. The invention as recited in claim 73, wherein said hot melt adhesive is polyolefin based hot melt adhesive.

76. The invention as recited in claim 73, wherein said second layer of resilient adhesive is a thermoset adhesive.

77. The invention as recited in claim 58, wherein the combined mass of the first layer of at least one resilient adhesive and the second layer of at least one resilient adhesive is not greater than about100 ounces per square yard.

78. The invention as recited in claim 58, wherein the stabilizing material comprises a sheet of non-woven fiber glass.

79. The invention as recited in claim 58, wherein the first layer of at least one resilient adhesive comprises a hot melt adhesive and the second layer of at least one resilient adhesive comprises a hotmelt adhesive.

80. The invention as recited in claim 79, wherein the stabilizing material substantially separates the first layer of at least one resilient adhesive from the second layer of at least one resilient adhesive.

81. The invention as recited in claim 58, further comprising a backing structure disposed across the lower side of the rebond foam cushion layer.

82. The invention as recited in claim 81, wherein the backing structure comprises a multi-component composite.

83. The invention as recited in claim 82, wherein said multi-component composite comprises a layer of adhesive disposed adjacent the lower side of the rebond foam cushion layer.

84. The invention as recited in claim 83, wherein said layer of adhesive disposed adjacent the lower side of the rebond foam cushion layer is present at a level of not greater than about 40 ounces persquare yard.

85. The invention as recited in claim 81, wherein said backing structure comprises a multi-component composite including a quick release backing.

86. A process for producing a carpet composite comprising the steps of: modifying a rebond foam pad of approximately 5-25 pounds/cubic foot density to have a respective non-woven materialbonded to each of the upper and lower surfaces thereof and with the composite rebond pad having a thickness of approximately 0.25 inch or less, slitting the composite rebond pad in half, producingtwo foam backings, each approximately 0.125 inch thick or less with a non-woven material attached to one surface, and bonding at least one of the foam backings using an adhesive to the back of atleast one of a tufted carpet and a bonded carpet.

87. A carpet composite formed by the process of claim 86.

88. A carpet tile comprising a carpet layer and a backing attached thereto and having at least one layer comprised of compressible particles bonded together.

89. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together has an internal tear strength of at least 3 lbs.


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90. The carpet tile as recited in claim 88, wherein the layer of compressible particles bonded together is a compressed particle foam and has a compressibility of less than 100% of the foam thicknessat 40 psi.

91. The carpet tile as recited in claim 88, wherein said carpet tile has an appearance retention rating of at least 4.0 after 4,000 cycles.

92. The carpet tile as recited in claim 91, having an appearance retention rating of at least 3 after 12,000 cycles.

93. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together is at least one of a cut, slit and peeled foam.

94. The carpet tile as recited in claim 88, wherein said layer has a recycled content of at least 85%.

95. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together is an open celled foam comprised of open celled foam particles bonded together.

96. The carpet tile as recited in claim 95, wherein the open celled foam is comprised of foamed polyurethane.

97. The carpet tile as recited in claim 88, wherein said particles bonded together have an average uncompressed chip size of 25 mm or less.

98. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together has a density of 25 lbs/ft3.

99. The carpet tile as recited in claim 88, wherein said layer has a recycled content of at least 50%.

100. The carpet tile as recited in claim 88, having a hexapod rating >2.0 at 12,000 cycles.

101. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together is one layer of a hot melt laminated carpet backing.

102. The carpet tile as recited in claim 88, wherein said layer comprised of compressible particles bonded together is one layer of a flame laminated carpet backing.

103. The carpet tile as recited in claim 88, having an initial Gmax of less than 125.

104. The carpet tile as recited in claim 88, having a cushion weight of less than 32 oz/yd2 and an initial Gmax less than 125.

105. The carpet tile as recited in claim 88, wherein the layer of compressible particles bonded together has at least one of a honey-combed, reticulated, and skeletal open cell structure.

106. The carpet tile as recited in claim 88, wherein the layer of compressible particles bonded together has a structure of randomly placed particles bonded together in a compressed state.

107. The carpet tile as recited in claim 88, wherein said layer of compressible particles bonded together is substantially free of any filler.

108. The car

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