Preparation of Finely Divided Mixtures of Amphiphilic Polymers and Polycarboxylates and Use Thereof

A 15% strength aqueous dispersion of a polyester which contained polyethylene terephthalate and polyoxyethylene terephthalate units in a molar ratio of 1.5:1.0 and had a molecular mass M.sub.w of 8000 and polyethylene oxide segments of molecular mass M.sub.n of 1500 was vigorously mixed at room temperature with a 60% strength aqueous solution of 70% acrylic acid and 30% maleic acid copolymer with a molecular mass M.sub.w of 70000 which had been partially neutralized with sodium hydroxide solution in a weight ratio of polymers of 1:3. The pH of the aqueous copolymer solution had been adjusted to 4.5 prior to the addition of the dispersion of the soil release polymer. The resulting stable dispersion was continuously stirred and sprayed into a laboratory spray dryer to obtain a fine colorless, storage-stable and readily free-flowing powder having an average particle size of 170 .mu.m.

A 15% strength aqueous solution of the amphiphilic polymer described in Example 1 was mixed at room temperature with such an amount of a 22.6% strength aqueous solution of a polyaspartic acid of molecular mass M.sub.w 12 000 (the pH of the aqueous solution was 4.5) that the weight ratio of the polymers was 1:3. The resulting dispersion was continuously stirred and sprayed into a laboratory spray dryer to obtain a fine colorless, storage-stable and readily free-flowing powder which had an average particle size of 130 .mu.m.

A 15% strength aqueous dispersion of the amphiphilic polymer described in Example 1 was mixed at room temperature with such an amount of a 24.7% strength aqueous solution, adjusted to pH 3.5, of an oligocitric acid which had been partially neutralized with sodium hydroxide solution, that the weight ratio of the polymers was 1:3.

The oligocitric acid was prepared as follows:

96.0 g of anhydrous citric acid were dissolved in 96 g of dioxane at 60.degree. C., and 25.5 g of acetic anhydride were added over 1 h. After a further 30 min at 60.degree. C. the temperature was raised to 100.degree. C. and held at 100.degree. C. for 1 h. The batch was then cooled back down to 60.degree. C. The cycle of acetic anhydride addition, tempering at 60.degree. C., heating-up to 100.degree. C. and cooling was repeated a further three times, 25.5 g, 10.2 g and 10.2 g of acetic anhydride being added respectively. The glacial acetic acid/dioxane azeotrope was then distilled off in a rotary evaporator. Remaining acetic acid was removed by twice adding 200 g of dioxane each time and distilling off the dioxane/glacial acetic acid mixture.

The resulting stable dispersion of polyester in the aqueous solution of the oligocitric acid was laboratory spray-dried into a fine colorless storage-stable readily free-flowing powder having an average particle diameter of 190 .mu.m.

A 15% strength aqueous dispersion of the amphiphilic polymer described in Example 1 and a 44.8% strength aqueous solution, adjusted to pH 4.5 with sodium hydroxide solution, of a partially neutralized oligomaleic acid of molecular mass M.sub.w 950 were mixed at room temperature in a weight ratio of 1:3, based on the polymers, and the mixture was thoroughly stirred for 15 minutes. The resulting stable dispersion was then spray-dried in a laboratory spray dryer to produce a fine, colorless storage-stable and readily free-flowing powder which had an average particle size of 120 .mu.m.

A 15% strength aqueous solution of an amphiphilic polyester which contained polyethylene terephthalate and polyoxyethylene terephthalate units in a molar ratio of 4:1 and had a molecular mass M.sub.w of 10000 and polyethylene glycol blocks of molecular weight M.sub.n of 4000 and a 45% strength aqueous solution, adjusted to pH 3.5 with sodium hydroxide solution, of citric acid were mixed at room temperature in a weight ratio of 1:3, and the resulting mixture was thoroughly stirred. The resulting stable dispersion was then spray-dried in a laboratory spray dryer to obtain a fine, colorless, storage-stable and readily free-flowing powder which had an average particle size of 240 .mu.m.

A 15% strength aqueous dispersion of the amphiphilic polyester described in Example 5 and a 43.2% strength solution of a terpolymer of 40 mol % of acrylic acid, 10 mol % of maleic acid and 50 mol % of vinyl acetate were mixed at room temperature in a weight ratio of 1:3, based on the polymers. The terpolymer had a molecular mass M.sub.W of 5000. The aqueous solution of the terpolymer had been adjusted to pH 3.5 with sodium hydroxide solution. The result obtained was a stable dispersion of the amphiphilic polyester in the aqueous partially neutralized terpolymer solution. This dispersion was spray-dried in a laboratory spray dryer. The result was a fine colorless, storage-stable and readily free-flowing powder which had an average particle size of 180 .mu.m.

A 20% strength aqueous solution of a graft copolymer of 1.6 parts of vinyl acetate on 1 part of polyethylene oxide, molecular mass M.sub.n 6000, was heated to 50.degree. C. and mixed with a 40% strength aqueous solution of the partially neutralized copolymer of acrylic acid and maleic acid described in Example 1 in a weight ratio of 1:10, based on the polymers. The result obtained was a stable dispersion which was free-flowing at room temperature and had a viscosity of 1800 mPas. This dispersion was subsequently spray-dried to a powder having an average particle size of 270 .mu.m.

The 20% strength aqueous solution of the graft copolymer described in Example 7 was mixed at 50.degree. C. with a 40% strength aqueous solution of the partially sodium hydroxide neutralized oligocitric acid described in Example 3, in a weight ratio of 1:10, based on the polymers. The result obtained was a solution which had a viscosity of 980 mPas and was free-flowing at room temperature. This solution was spray-dried into a powder which had an average particle size of 260 .mu.m.

The soil release properties of the above-described pulverulent polymer mixtures were determined in a wash test. The wash conditions are indicated in Table 1. The test fabric was prewashed three times; then its reflectance R.sup.1 was determined with a Data color 2000. The test fabric was then soiled with used engine oil. After the engine oil had been on the test fabric for 24 hours the reflectance R.sup.2 of the soiled test fabric was determined. The test fabric was then washed once more and the reflectance R.sup.3 measured. The soil release SR in percent was calculated according to the formula

Table 2 contains the composition of the test detergents used. The detergent formulation indicated in Table 2 contained in each case such an amount of product from the indicated example that it was 1% strength in respect of soil release polyester.

The results in Table 3 show that in all cases the soil release (SR) was above 80%, as is also the case for a dispersion of the active ingredient only. This means that formulation as a spray-dried powder in a mixture with poly(sodium carboxylate)s does not affect the activity of the polymer.

The dispersibility of a mixture of acrylic acid-maleic acid copolymer (sodium salt, pH 4.5) and the amphiphilic polyester of Example 1 prepared by spray drying according to the present invention was compared with the dispersibility of a mixture of the same composition prepared by the process described in Example 1 of U.S. Pat. No. 4,569,772 by stirring the mixtures for 10 min in 5% strength in water and removing the insolubles by filtration with a suction. The tests were carried out at 20.degree. C. and 40.degree. C. Table 4 shows the results.