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Advanced technologies

THE ROLE OF SODIUM- POLY(ACRYLATES) WITH DIFFERENT WEIGHT-AVERAGE MOLAR MASS IN PHOSPHATE-FREE LAUNDRY DETERGENT BUILDER SYSTEMS

Vladimir S. Milojević1*, Snežana Ilić-Stojanović2, Ljubiša Nikolić2, Vesna Nikolić2, Jakov Stamenković2, Dragan Stojiljković2

1 Henkel Srbija D.O.O., Bulevar Oslobođenja 383,Belgrade, Serbia2 The Faculty of Technology, University in Niš, Leskovac, Serbia

In this study, the synthesis of sodium-poly(acrylate) was performed by polymeri-zation of acrylic acid in the water solution with three different contents of potassi-um-persulphate as an initiator. The obtained polymers were characterized by using HPLC and GPC analyses in order to define the purity and average mo-lar mass of poly(acrylic acid). In order to investigate the influence of sodium-poly(acrylate) as a part of carbonate/zeolite detergent builder system, secondary washing characteristics of powder detergent containing equal percentage of sodium-poly(acrylate) were examined. The degree of whiteness and the ash content as main secondary washing performances significantly depended on the efficiency of sodium-poly(acrylate) used as crystal inhibitor, stabilizer for suspended soil and agent for preventing the soil redeposition at fabric surface. The decrease of the sodium-poly(acrylate) activity within the detergent builder system worsens its capability to prevent textile fiber damages and, as a result influences the worsening of detergent secondary washing performances. The degree of whiteness for cotton fabrics increased with the degree of polymeriza-tion and medium-weight molecular mass, Mw, up to the value of 70000 g/mol. In the case of further increase of the average molar masses, up to 100000 g/mol or higher, the builder performance began to decline. The ash content de-creased with the increase of the weight average molar masses from 3000 to 100000 g/mol, after which it started to increase again with the weight average molar mass increase. The highest value was reached in the samples of the detergent containing sodium-poly(acrylic) with the average molar mass close to 500000 g/mol. The effectiveness of sodium-poly(acrylate) with all examined molar masses did not decline or change significantly with the number of washing cycles performed.

Keywords: Sodium-poly(acrylate), polymer, detergents, carbonate/zeolite builders, second-ary washing performances, degree of white-ness, ash content

Introduction

Detergent formulations are finely balanced. The build-ing blocks of the detergent formulation (surfactants, build-ers, and specific additives such as bleach, enzymes etc.) must complement each other in their modes of action. Al-though the performance of detergent formulations derives from the system as a whole, it can be simplified as a com-position of more or less independent subsystems. One of these subsystems is the builder. The builder is expected (i) to provide the binding capacity for calcium and magne-sium ions in hard water [1], (ii) to disperse sparingly solu-ble salts, e.g. calcium carbonate, and prevent them from growing into larger crystals which deposit on surfaces [2], (iii) to suspend colloidal soil in the wash liquor, preventing it from redeposition and graying the fabric, (iv) to buffer

the pH of the wash liquor and maintain its alkalinity and, overall, (v) to boost the performance of the surfactants and thus help to improve soil removal [3].

Surfactant efficiency is greatly reduced in hard water but they also do not show the appropriate performance even in softer water. Furthermore, large amounts of sur-factants in detergents not only significantly increased the biological demand in water but also imposed heavy load on sewage works and on the environment due to their eco-toxicity. To remove Ca2+ and Mg2+ ions existing in hard water and in soils, and to lower the content of surfactants in detergent formulations, detergency build-ers are often used together with surfactants. A potential builder should satisfy a large number of requirements

(ORIGINAL SCIENTIFIC PAPER)UDC 678.7 + 547.391.1 :661.185.6

* Author address: Vladimir Milojević, Orašačka 15, 37000 Kruševac, SerbiaE-mail: [email protected] manuscript received: May, 31, 2013.Paper accepted: Jun, 13, 2013.

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including sequestering ability, alkalinity, buffer capacity, bleach compatibility, soil deflocculation, oral toxicity, skin absorption, eye irritation, the effects on fish and other aquatic animals and other environmental and economic practicability [4].

Sodium tripolyphospate (STPP) meets the essential requirements of a builder and therefore it was the most widely used builder in the past. In addition to its great capacity to remove Ca2+ and Mg2+ ions presented in hard water and in soils, STPP facilitates the dissolution of de-tergents, maintains alkalinity during washing, prevents dirt reposing on fabrics by suspending it in the wash-liq-uor and protects the washing machine against corrosion and shows the efficient performance under all washing conditions. However, phosphates are the excellent ferti-lizer for algae, bacteria and other flora and fauna in riv-ers, lakes and oceans, making them bloom at very rapid rates, exhausting the oxygen supply both in the surface and in the bottom layers of water bodies and fish and plant life die. This phenomenon is called eutrophication [5]. Though the removal of phosphates from the sewage in treatment plants could eliminate 80-95 % of all phospho-rus, the cost is considered too high to allow the immedi-ate and general application [4]. In the mid-1980’s, some countries imposed restrictions on the use of phosphates in household laundry detergents. Subsequently, other water softeners such as sodium-carbonate and sodium silicate and ethylenediaminetetraacetic acid (EDTA) were used as a substitute for STPP. Although sodium- carbonate and sodium silicate- built detergents show al-most the same performance as the leading phosphate formulations, their high alkalinity is harmful to our skin and eyes. In addition, they produce deposits on fabrics which trap dirt, provide a breeding ground for bacteria and cause washed fabrics to become harsh, grey and to wear out more quickly. Nowadays, zeolites, particularly zeolite A, are used in phosphate-free detergents, necessarily together with other builders such as ploycarboxylates, EDTA and sodi-um-carbonate. Zeolite A possesses a good ion exchange capacity for the Ca2+ ion in hard waters and soils and its performance is enhanced in concentrated detergent formulations due to the lower total salt normality and lower background of Na+ ions [6]. The advantages of zeolites over other builders are that they i) offer a very high product stability and no decomposition; (ii) are inert under elevated temperatures, mechanical influences or alka-linity; (iii) inhibit greying and dye transfer; (iv) help in the formulation of high performance, low cost, eco-friendly phosphorus free detergents; (v) remove hardness from wash water; (vi) have high liquid absorption capacities and (vii) they are free of legislative restrictions. Howev-er, the absorption rate of zeolite A is much lower than STPP and a small ion exchange capacity is found for the Mg2+ ion [7,8]. The use of zeolites increases suspended solids and may cause fouling of pipeline. It significantly increases sludge volumes in sewage treatments plants making the disposal of sludge more difficult. In addition, the surfactant in the zeolite detergent is trapped inside

the zeolite and it takes time to diffuse into wash liquor. To compensate for the shortcomings as a detergent builder, an alkaline compound such as soda ash or sodium sili-cate is added.

Polycarboxylates, such as homo- and copolymers of acrylic acid or maleic acid, show a marked superiority to STPP in their ability to sequester calcium ions, prevent incrustration of fibers and re-dissolve calcium salt pre-cipitates [4,5]. A sequestrant builder is incorporated in an anionic detergent product formulation for a specific pur-pose of preventing the loss of anionic surfactant through precipitation as its insoluble calcium salt. The free calci-um ion concentration at which this surfactant loss begins is determined by the solubility product (Ksp) of Ca (LAS)2, or Ca (SDS)3, and averages of about 5x105 moles/liter of hardness ion or 5 ppm as CaCO3. Poly(acrylates) are effective calcium and magnesium ion sequestrates and can be used to partly replace STPP in low or zero-phosphate detergents. They can also be used synergisti-cally with other low cost builders like zeolite and sodium citrate to obtain better “protection” for the anionic sur-factant in a total detergent formulation. Detergency is the wash benefit arising from the soil removal, stabilization of the soil in the wash liquor and prevention of soil re-deposition. Soil is a complex mixture of particulate and oily soiling materials such as sweat sebum, street dirt, household soil, occupational soils and deposits of in-soluble calcium/magnesium salts normally present in the wash water. The use of these polymers leads to highly desirable end-use effects such as improved detergency, anti-redeposition, lime soap dispersancy, anti-encrus-tation, iron sequestration and anti-spotting. One of the major reasons why polycarboxylates play an important role in European detergents is the need to prevent en-crustation of fabrics and washing appliances caused by high water hardness. The wealth of literature deals with mechanistic aspects of the mode of action of polycarbox-ylates in the washing process. Their performance cor-relates with their ability to disperse particles rather than with their calcium ion-sequestering properties [1]. Based on these findings, the prevention of carbonate encrusta-tion was viewed as a consequence of crystal growth in-hibition by polycarboxylates adsorbed onto the growing crystal face [2]. Recently published results indicate that this model of a linear straightforward process may be too simplified, as different pathways are likely to be involved simultaneously. The contribution of each individual path to the whole process may also be dependent on the ad-ditive [10]. Under experimental conditions allowing the extremely high local resolution, as well as time resolution in the millisecond range, the evidence obtained showed that polycarboxylates covered primary CaCO3 particles extremely quickly and efficiently, giving rise to floc-like microscopic agglomerates rather than crystals. This sug-gests that polycarboxylates mechanistically act both on the primary agglomeration step to prevent the formation of crystals and on their subsequent growth into larger crystals. The adsorption of polyacrylates onto soil par-

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ticles help in breaking down large (50-100 μm) soil ag-glomerates into much smaller (10 μm and below) parti-cles. These particles then remain as stable dispersions to be discarded in a normal rinse cycle during a stand-ard washing operation. Sodium-poly(acrylate) is a linear, soluble macromolecular compound, their shuttle based on molecular chain due to electrostatic repulsion, the polymer chain stretch, adsorption function of mission led to an exposed on the surface, adsorbed on suspended particles in the solution of these activity, form a bridge between particles, thus speeding up the settlement of suspended particles. Therefore sodium-poly(acrylates) can be used for flocculants.

Polycarboxylates are essential components of pow-der detergents, not only as cobuilders. Aside from their impact in the laundering process they play an important role in the manufacture of detergent powders and tab-lets. They contribute to the adjustment of their morphol-ogy and their physical properties and they are of vital importance as a process aid already on the first stage of manufacturing, in the slurry preparation and spray drying [11]. Optimizing the slurry preparation is crucial for the efficiency of the whole spray drying step. Due its excellent performance in reducing the viscosity, polycar-boxylates allows to increase significantly the content of solid matter in detergent slurry and to reduce the water content, respectively. This will result in substantial en-ergy savings in the spray drying process. Further, the increased solid content will directly lead to the increase of the operational plant capacity of spray drying units at unaltered volumes of mixing vessels.

Beyond its excellent performance as a process aid, polycarboxylates features very good cobuilder proper-ties in the laundering process as well.

Ecological properties of detergent polycarboxy-lates. Acrylic acid based laundry polymers are not bio-degradable according to OECD criteria. They are elimi-nated from wastewaters by precipitation or adsorption to sludge. The extent of elimination increases with increas-ing M W [12].The polymer is also removed from standing or slow-moving surface waters by adsorption on floating particles or by contact with the sediment. These laun-dry polymers do not remobilize heavy metals from river sediments [13] and the high affinity of polycarboxylates for soil materials results in their immobilization in sedi-ments or soils. This in turn explains why, compared to dissolved substances, they are much more resistant to attack by microorganisms and hence to biodegradation. Besides their eco-compatibility, polycarboxylates have also proven to be toxicologically safe. No toxic effects were observed with the high-M W copolymer in acute and chronic tests on various aquatic organisms. Also the tox-icity to mammals is very low. It does not irritate the skin or mucous membranes, and it does not promote skin sensitization. Furthermore, no mutagenic effects were observed in different test systems [14].

The paper focus on study the effects of poly(acrylate) molecular weight, used as a cobuilder, on detergent sec-

ondary washing performance.

EXPERIMENTAL

Reagents:Sokalan PA30CL, 45 %, sodium-poly(acrylate), M w

8000g/mol (BASF, Germany)Sokalan PA70PN, 30 %, poly(acrylic acid)/ sodium-

poly(acrylate), M w 70000g/mol (BASF, Germany) Sokalan PA80S, 35 %, poly(acrylic acid), M w

100000g/mol, (BASF, Germany)Sodium-Hydroxyde, 99 %, (Merck, Germany)Persulphate-Potassium, 98 %, PP (Riedel-de-Haen,

Seelze, Germany)Acrylic Acid, 99 º%, AA (Merck, Holenbrunen, Ger-

many)

The synthesis of basic powder detergent. Semi-tower, without the addition of sodium-poly(acrylate), is manufactured in an industrial batch process method of slurry preparation [15,16]. Slurry was sprayed at a pres-sure of 25bar in an industrial tower Ballestra (Ballestra, Milan) using a two-level of Delawan nozzles, with the hole diameter of 4,3mm with swirl chambers SDXV SWC Swirlchamber SH Flat Back Face and dried in the hot air temperature of 142 ºC in countercurrent flow regime. Ba-sic detergent was obtained by adding thermo-unstable components to the tower powder detergent in rotary mix-er Compomix (Henkel CEE, Vienna) at a speed of 39rpm.

The synthesis of testing powder detergent. Soka-lan PA70PN and Sokalan PA80S were neutralized in the laboratory by using the 0,01mol/dm3 sodium-hydroxide solution, until neutral reaction was reached. The final detergent formulations used to investigate secondary washing performances were obtained in the laboratory by mixing of sodium-poly(acrylate) with the different weight average molar mass (Sokalan PA30CL, Soka-lan PA70PN, Sokalan PA80S or laboratory syntetized sodium- poly(acrylate)) and basic powder detergent. Cobuilder weight ratio in the detergent powder builder system sodium-carbonate/zeolite/sodium-poly(acrylate) was 9,2:2:1.

Washing test performance. With each of the sam-ples of sodium-poly(acrylate) testing was performed by 50 washing cycles in the washing machine Gorenje WA512, filled with 3,5kg of white cotton laundry, com-posed as it is given in Table 1.

The wash cycle includes washing with the water of to-tal hardness 9,35 ºdH, scouring at 95 ºC, rinse cycles, in-termediate and final spin. Uncontaminated control cotton fabric Krefelder Standardgewebe wfk 11A was added at the beginning of the cycle, and after every 5 performed cycles the sample to testing the degree of whiteness and ash content was taken. The samples were dried in hot air at 60 ºC in a closed and darkened room.

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Table 1. List of appendix clothes for washing tests per one ma-chine load

The synthesis of poly(acrylic acid). For the synthesis of poly(acrylic acid), water solution of AA was prepared. PP was used as the initiator with different concentrations compared to the mass of AA given in Table 2.

Table 2. Composition of solution for the synthesis of poly(acrylic acid)

The polymerization was conducted for 135 min at 80 ºC and after that the poly(acrylic acid) solution cooled down to the room temperature. At the end, poly(acrylic acid) was neutralized in the laboratory by using the 0,01 mol/dm3 sodium-hydroxide solution, until neutral reaction was reached.

Degree of whiteness tests. To test the degree of whiteness of the fabric samples, Datacolor 600 spectro-photometer (Datacolor) was used. The control fabric was folded in half twice so that the ironed side of the sample was on the side illuminated by a lamp. The fabric was exposed to the effects of light fits CIE standard light D65 (CIE 45-15-145). Refractometer measured the value R (%), light re-flected from the surface of fabric in the wavelength range 360-700nm at ten different points on the fabric surface. The value obtained at a wavelength of 470 nm was taken as a relevant Refractometric value, R (%).

Examination of the ash content. The examination of the ash content after combustion of the control fabric sample was performed by using the gravimetric meth-od. The sample with the mass of 3 g, calculated on the weight of dry fabric (m0), was prepared. The sample of the cotton fabric was pre-burned by free combustion in an empty pot with the specified weight (m1), and then ex-posed to the final combustion in the furnace Nabertherm LE4/11/R6 for 1h at 800 ºC. After the final combustion, the mass of the pot with the ash included (m2) was meas-ured. The content of total remains (A), expressed as a

percentage, was calculated by the equation 1:

.......................................................(1)

Characterization of the obtained polymers and cotton fabrics

SEM microscopy. In the preparation phase of the cot-ton fabric samples for SEM microscopy, a thin layer of gold was applied on the surface by using the technique of cathode spraying with the diffuser JEOL JFC-1100E. SEM microscopy was performed by using the scanning electronic microscope JEOL JSM-5300.

Determination of residual monomer by HPLC method. Shredded polymer samples (25 mg) were im-mersed in methanol (25 cm3) and the residual monomer extraction was performed during 48 h. The methanol so-lution was separated from the polymer by filtration, while the concentration of poly(acrylic acid) in methanol was determined by HPLC under the following conditions- column: XDB ZORBAX C-18, 250 x 4,6 mm, 5 µm; eluent: 80 %meth-anol/20 % redestilated water; flow rate: 0,65 cm3/min at the pressure 125 bar; column temperature: 25 °C, detec-tor: DAD; UV detection: 205nm.

Determination of the molecular weight by GPC method. The solution of polymer samples was prepared by dilution with water to the concentration of 5 mg/cm3. After filtration, M w distribution of poly(acrylic acid) sam-ples was determined by GPC under the following con-ditions- column: ZORBAX PSM300; eluent: redestilated water; flow rate: 1 cm3/min at the pressure 90 bar; col-umn temperature: 30 °C, detector: DAD; UV detection: 205 nm

RESULTS AND DISCUSSION

Residual monomer determination. In the samples of poly(acrylic acid) the amounts of residual monomers of AA were determined by HPLC method. Residual amounts of monomers were determined in order to con-firm AA conversion rate during the polymerization pro-cess. HPLC chromatogram shows a retention time of AA, Rt = 3,051 min, and the UV spectrum shows the wave-length of the maximum absorbance λ max = 205 nm. For a series of solutions of AA in acetone HPLC chromato-grams were done and for each concentration the specific surface area of the obtained peaks were determined by using Agilent ChemStation software.

0m100*)mm(

A12 −

=

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The dependence of the peak (in units of internal soft-ware mAU*s) which is derived from AA in the function of the concentration shows that the dependence is not linear throughout the range of concentrations of AA monomer up to 1 mg/cm3. As shown in Figure 1. the linearity exists up to the concentration of 0.2 mg/cm3.

Figure 1. The residual monomer calibration curve: the depend-ence of the peaks surface on HPLC chromatograms depending on the concentration of acrylic acid; detection 205 nm, reten-tion time of peak 3,05 min.

For the peak surface up to 44000 mAU*s and for this range of the concentration, the equation 2 can be ap-plied:

.....................................(2)

where A is the peak surface, mAU*s, and C is the con-centration of the monomer, mg/cm3. From Equation 2 the

equation 3 can be obtained by which the concentration of the monomer from certain peak surfaces for the linear range of monomer concentration can be calculated.

..............................................................(3)

From the concentration of the residual monomer in the extracts, the mass of the unreacted monomer per gram of polymer was calculated and these results are shown in Table 2. Generally, it can be concluded that af-ter polymer was synthesized, the concentrations of re-sidual monomers significantly lowered reaching the val-ues of 0.0139 to 0.0426 mg/ cm3. It is estimated that the mass of the residual monomers would not significantly affect the performance of polymer during the washing tests, so no other treatment of polymer is needed. Table 4 shows the mass of residual monomers in the samples of poly(acrylic acid) made with different quantities of the initiator, PP.

Table 4. Mass of residual monomers in the samples of poly(acrylic acid)

Determination of the molecular weight by GPC method. Determinations of the average mass molecular weight of synthesized poly(acrylic acid), used for further examinations of detergent secondary washing perfor-mance was performed by using the GPC method. The results of examinations are shown in Table 5.

Table 3. The values of the peak areas at Rt = 3,05 min from the HPLC chromatograms of acrylic acid

Table 5. Molecular weights of poly(acrylic acid) in the samples made with different quantities of the initiator, PP

C283924,721156,28A ⋅+=

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Figure 2 shows SEM image of the control cotton fabric before the washing-test treatment with the tested powder detergent. The fabric contained a high number of textile fibers wrapped together into the more structured fabric structures, with the approximately cylindrical shape and very smooth surface.

Figure 2. SEM image of sodium-poly(acrylate), cotton fabric before washing tests; magnification x 2000, bar = 10 µm

The condition of textile fibers was rechecked after fin-ishing the trials of 50 washing cycles. In the fabric tested with the detergent containing sodium-poly(acrylate) with the weight average molar mass of 100000 g/mol (Soka-lan PA80S) the damages over the textile fibers were no-table, compared to the fabric fibers before the washing-test performance. However, damages were present just in a part of the fabric, appeared only at the fiber surface, without some deeper fiber structure damages as shown in Figure 3.

Figure 3. SEM image of sodium-poly(acrylate), Sokalan PA80S; magnification x 2000, bar = 10 µm

With the molecular weight increase, the damages became more present and visible, with a much higher level of damage. SEM image of the fabric sample tested with the detergent containing sodium-poly(acrylate) with the weight average molar mass of 436840 g/mol shows primary layers of textile fibers fully damaged, interwoven between each other all over the fabric surface as shown in Figure 4.

Figure 4. SEM image of sodium-poly(acrylate), sample 1; mag-nification x 2000, bar = 10 µm

With further sodium-poly(acrylate) weight average molar mass increase, up to 474920 g/mol, fiber damages became deeper and deeper, fiber layers became more and more interwoven, in some parts influencing com-plete loosing of textile pre-structure as shown in Figure 5.


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The cotton fabric tested by detergent with the high-est sodium-poly(acrylate) weight average molar mass, 523100 g/mol, after finishing the 50 wash-test cycles, showed the highest level of fiber damage. Textile fibers were smeared all over the textile structure, introducing a complete joining of fibers in some parts. Irregular dam-ages took place instead more or less regular ones noti-fied with the previous, lower molecular weight samples of sodium-poly(acrylate). Fiber fanning started not to be in a way that one layer removal was following the complete removal of previous ones- at the same time several lay-ers in textile fiber started to be damaged, as shown in Figure 6.


Degree of whiteness tests. The values of the de-gree of whiteness after washing with detergent con-taining sodium-poly(acrylate) with different molecular weights depending on the number of washing cycles are shown in Figure 7.

Figure 7. The influence of the number of washing cycles (N) on the reflectivity of the cotton fabric (R) in case of detergents con-taining sodium-poly(acrylate) with different values of molecular mass

The highest value indicates the degree of whiteness of the fabric sample after washing with the detergent containing sodium-poly(acrylate) with the molecular weight of 70000 g/mol, slightly above the value of the pattern fabric washed with the detergent containing so-dium-poly(acrylate) molecular weight of 100000 g/mol. Detergent samples containing sodium-poly(acrylate) with high molecular weight values, between 436840 g/mol and 523100 g/mol, showed a lower degree of whiteness val-ues, while the lowest values were notified in the case of the fabric washed with detergent samples containing sodium-poly(acrylate) with the lowest molecular weight, 8000 g/mol. The values of the degree of whiteness within a series of washing detergents containing sodi-um-poly(acrylate) with the same high-mass molecular weight did not differ significantly, regardless the number of washing cycles.

Examination of the ash content. The values of the ash content after washing with the detergent containing sodium-poly(acrylate) with different molecular weights depending on the number of washing cycles are shown in Figure 8.

Figure 8. The influence of the number of washing cycles (N) on the ash content of the cotton fabric in the case of deter-gents containing sodium-polyacrilates with different values of molecular mass

The highest value of the ash content after combus-tion, which corresponds to the content of the inorganic residue after annealing, was recorded in the case of the control fabric treated with detergent formulation contain-ing the highest molecular weight sodium-poly(acrylate) (above 400000 g/mol), ahead of the control fabric treat-ed with a detergent formulation containing low molecu-lar weight sodium-poly(acrylate) (8000 g/mol), while the lowest values of the ash content were notified in the case of the fabric treated with the detergent formulation con-taining sodium-poly(acrylate) with the average molecular weights (70000-100000 g/mol). In the case of all sam-ples, after the 25th washing cycle the ash content lead to a slight increase with the number of washing cycles.

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CONCLUSION

The results of this study showed that different mo-lecular weight sodium-poly(acrylates) can be used as an effective remedy for builder’s ability improving in sodium-carbonate/zeolite detergent formulations and therefore secondary washing performance of laundry detergents. Poly(acrylates) with the higher weight average molar mass, containing a higher number of charges have a greater capacity to bind metal ions as well as the possi-bility of binding in their structure agglomerates of heavy- soluble salts. As the most effective, in terms of stability and prevention of impurity suspension redeposition on the fabrics surface has to be sodium-poly(acrylate) with the weight average molar mass of 70000 g/mol. In spite of increased charges on it, high molecular weight sodium-poly(acrylate) with the weight average molar mass high-er than 100000 g/mol showed to be the least effective in the detergent builder system. Steric obstructions prevent molecules of sodium-poly(acrylate) to interfere with other suspended molecules and effectively act on the surface between the fabric fiber and suspended impurities. Due to the increased size of molecules, long polymer chains of sodium-poly(acrylate) with the weight average molar mass higher than 100000 g/mol are facing serious dif-ficulty to perform a successful transfer of metal ions from the suspension of the impurity particles to the zeolite, re-sponsible for its binding. A decreased level of the builder performance caused by insufficient poly(acrylate) sup-porting activity leads to lower protection of textile fibers, increased damage at the fiber surface and through the whole structure, influencing deterioration of visual char-acteristics, fabric strength and material life-time. The ef-fectiveness of all molecular weight sodium-poly(acrylate) does not decline or change significantly with the number of washing cycles performed.

ACKNOWLEDGEMENTS

This work was supported by the Ministry of Educa-tion, Science and Technological Development of theRepublic of Serbia under the project TR-33034

ABBREVIATIONS AND SYMBOLS

PP- Persulphate potassiumAA- Acrylic AcidEDTA- ethylenediaminetetraacetic acidD- Dispersity indexR- Refractometric valueSTPP- Sodium tripolyphospateMn - Number average molar mass Mw - Weight average molar mass Mz - Z average molar mass

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[3] W. Berleff, P. Neumann, R.Baur, D, Kiessling, Aspects of Polymer Use in Detergents, J. Surfactants Deterg. 1 (3) (1998) 419-424.

[4] Schaffer, J.F., Woodhams, R.T., “Polyelectrolyte builders as detergent phosphate replacements”, Ind. Eng. Chem., Prod. Res. Dev., 16 (1977) 3-11.

[5] Schindler, D.W., “Eutrophication and recovery in experimental lakes: Implications for lake management”, Science, 184 (1974) 897-899.

[6] Denkewicz, R.P., Monino, A.G., Russ, D.E., Sherry, H.S., “Measurement and interpretation of zeolite NaA builder performance”, J. Am. Oil Chem. Soc., 72 (1995) 31-35.

[7] Costa, E., Lucas, A., Uguina, M.A., Ruiz, J.C., “Synthesis of 4A zeolite from calcined kaolins for use in detergents”, Ind. Eng. Chem. Res., 27 (1988) 1291-1296.

[8] Nieuwenhuizen, M.S., Ebaid, A.H.E.F., van Duin, M., Kieboom, A.P.G., van Bekkum, H., “Cation exchange in the system Ca(II) or Mg(II)/complexing agent/zeolite NaA: Equilibria and kinetics”, Tenside Surfact. Det., 21 (1984) 221-225.

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[10] Rieger, J., E. Hädicke, I.U. Rau, and D. Boeckh, A Rational Approach to the Mechanisms of Incrustation Inhibition by Polymeric Additives, Tenside Surfactants Deterg. 34 (1997) 430-435.

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[13] Opgenorth, H.J., Polymeric Materials Polycarboxylates, in The Handbook of Environmental Chemistry, edited by O. Hutzinger, Springer-Verlag, Berlin/Heidelberg, 3 (F) (1992) 337–350.

[14] Product Information Sokalan®—Polymeric Dispersants, BASF, Ludwigshafen, Germany, 1992.

[15] D. Jung in: Ullmann's Encyclopedia of Industrial Chemistry, Wiley- VCH, Weinheim 1985, p.385.

[16] K. Masters: Spray Drying Handbook, Fifth Edition, Longman Scientific & Technical, New York 1991.

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ULOGA NATRIJUM- POLI(AKRILATA) RAZLIČITIH SREDNJE- MASENIH MOLEKULSKIH MASA U BILDERSKIM SISTEMIMA BEZFOSFATNIH

DETERDŽENATA ZA PRANJE RUBLJA

Vladimir S. Milojević1*, Snežana Ilić-Stojanović2, Ljubiša Nikolić2, Vesna Nikolić2, Jakov Stamenković2, Dragan Stojiljković2

1 Henkel Srbija D.O.O., Beograd, Srbija2 Univerzitet u Nišu, Tehnološki fakultet, Leskovac, Srbija

U ovom radu sinteza natrijum-poli(akrilata) izvršena je polimerizacijom akrilne kiseline u vodenom rastvoru, uz primenu tri različite koncentracije kalijum-persulfata kao inicijatora. Karakterisanje dobijenih proizvoda urađeno je pri-menom HPLC i GPC metoda u cilju definisanja rezidualnog monomera i sred-nje masene molekulske mase poli(akrilne kiseline) U cilju određivanja uticaja natrijum-poli(akrilata) kao kobildera u karbonat/zeolitnom bilderskom sistemu na sekundarne karakteristike pranja deterdženta, ispitivane su sekunda-rne karakteristike pranja deterdženata sa podjednakim sadržajem natrijum-poli(akrilata) različitih srednje masenih molekulskih masa Vrednost stepena beline i sadržaj pepela, najznačajnijih sekundarnih karakteristika pranja, u velikoj meri zavise od efikasnosti natrijum-poli(akrilata) u njegovoj primeni kao inhibitora rasta kristala, stabilizatora suspenzije nečistoća i agensa za sprečavanje ponovnog taloženja nečistoća na površini tkanine. Smanjena ak-tivnost natrijum-poli(akrilata) u bilderskom sistemu deterdženta umanjuje nje-govu sposobnost da spreči oštećenje tekstilnih vlakana, i kao rezultat toga prouzrokuje pogoršanje sekundarnih karakteristika pranja deterdženta. Ste-pen beline kontrolne pamučne tkanine raste sa povećanjem srednje masene molekulske mase natrijum-poli(akrilata), Mw, sve do vrednosti od 70000 g/mol, nakon čega sa daljim povećanjem srednje masene molekulske mase do vred-nosti od 100000 g/mol ili iznad, uloga bildera počinje da opada. Sadržaj pepela opada sa povećanjem srednje masene molekulske mase natrijum-poli(akrilata) od vrednosti 8000 do 100000 g/mol, nakon koje ponovo počinje da raste sa porastom molekulske mase. Najviše vrednosti sadržaja pepela postignute su kod uzorka deterdženata koji su sadržali natrijum-poli(akrilat) srednje masene molekulske mase od 474920 g/mol. Efikasnost natrijum-poli(akrilata) svih srednje masenih molekulskih masa ne smanjuje se niti značajno menja sa povećanjem broja ciklusa pranja.

Ključne reči: Natrijum-poliakrilat, polimer, de-tergent, karbonat/zeolitski bilderi, sekundarna svojstva pranja, stepen beline, sadržaj pepela

(ORIGINAL NAUČNI RAD)UDK 678.7 + 547.391.1 :661.185.6

Izvod

2(1) (2013), 60-68

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