阅读说明：本技术 制备水分散体的方法和由其制备的可再分散的分散体粉末 (Method for producing aqueous dispersions and redispersible dispersion powders produced therefrom ) 是由 C·施密特克 E·扬斯 T·盖德特 M·温克鲍尔 K·赛普 I·勒舍尔 于 2018-06-06 设计创作，主要内容包括：本发明涉及一种制备可再分散的分散体粉末的方法,可根据该方法获得的可再分散的分散体粉末,可根据该方法的步骤(1)获得的水分散体,含有可再分散的分散体粉末和/或水分散体的建筑材料组合物,可再分散的分散体粉末在建筑材料组合物中的用途,以及水分散体用于制备可再分散的分散体粉末的用途。(The invention relates to a process for preparing redispersible dispersion powders, to the redispersible dispersion powders obtainable according to this process, to the aqueous dispersions obtainable according to step (1) of the process, to building material compositions containing redispersible dispersion powders and/or aqueous dispersions, to the use of the redispersible dispersion powders in building material compositions, and to the use of the aqueous dispersions for preparing redispersible dispersion powders.)

1. A process for preparing a redispersible dispersion powder, the process comprising the steps of

(1) Mixing at least the following substances

(i) An aqueous dispersion, wherein the dispersion comprises particles, wherein the particles comprise at least one polymer I, wherein the polymer I comprises monomer units formed from at least one ethylenically unsaturated monomer; and

(ii) a polyacid II comprising monomeric units formed from at least one ethylenically unsaturated monomer comprising a sulfonic acid group or a salt therefrom;

wherein, in step (1), an additive comprising a polyoxyalkylene group, preferably a polyoxyethylene group wherein the degree of ethoxylation is from 6 to 50, is present, wherein the additive is

(a) As a further component to the mixture from step (1), or

(b) Applied to the surface of the particles in a preceding step by emulsion polymerization, or

(c) Polymer I incorporated as monomer units into the particles in a previous step;

and wherein the pH of the dispersion resulting from step (1) is < 4;

(2) drying the dispersion obtained from step (1) to obtain a redispersible dispersion powder.

2. The method of claim 1, further comprising the step of

(3) Mixing the redispersible dispersion powder from step (2) with

(iii) An anti-blocking agent.

3. The process according to claim 1 or 2, wherein the pH of the dispersion resulting from step (1) is preferably < 3.

4. The process of any one of claims 1 to 3, wherein polymer I comprises monomer units formed from at least one ethylenically unsaturated monomer selected from the group consisting of: ethylene, propylene, butadiene, styrene, vinyl acetate, vinyl chloride, vinyl ethers, vinyl esters, acrylic esters, methacrylic esters, and mixtures of the foregoing monomers.

5. The process according to any one of claims 1 to 4, wherein polymer I is selected from

(ia) a styrene- (meth) acrylate copolymer,

(ib) a styrene-butadiene copolymer,

(ic) (meth) acrylate copolymers, and

(id) ethylene-vinyl acetate copolymer.

6. The process of any of claims 1 to 5, wherein polyacid II comprises monomer units formed from at least one ethylenically unsaturated monomer comprising at least one sulfonic acid group or salt thereof and at least one other ethylenically unsaturated monomer selected from vinyl sulfonic acid, 2-hydroxy-3- (prop-2-enyloyloxy) propane-1-sulfonic acid, 2-hydroxy-3- [ (meth) acryloyloxy ] propane-1-sulfonic acid, 3-allyloxy-2-hydroxypropane-1-sulfonic acid, styrene-3-sulfonic acid, 3- (meth) allyloxybenzene-1-sulfonic acid, α -methylstyrene sulfonic acid, α -ethylstyrene sulfonic acid, allyloxybenzene sulfonic acid, (meth) allyloxybenzene sulfonic acid, bis (3-sulfopropyl) maleate, bis (2-sulfoethyl) maleate, bis (3-sulfopropyl) itaconate, bis (2-sulfoethyl) itaconate, 2-propene-1-sulfonic acid, 2-methyl-2-propenesulfonic acid, 4-propenoic acid, and salts of the aforementioned ethylenically unsaturated monomers, and mixtures of the aforementioned ethylenically unsaturated monomers, and salts of the aforementioned at least one monomer, and mixtures of the aforementioned ethylenically unsaturated monomers.

7. The process according to any one of claims 1 to 6, wherein the polyacid II comprises monomer units formed from at least one allylic monomer comprising at least one sulfonic acid group or salt thereof, selected from the group consisting of 3-allyloxy-2-hydroxypropane-1-sulfonic acid, 3- (meth) allyloxybenzene-1-sulfonic acid, allyloxybenzene sulfonic acid, (meth) allyloxybenzene sulfonic acid, 2-propene-1-sulfonic acid, 2-methyl-2-propene-1-sulfonic acid, and salts of the foregoing acids, and mixtures of the foregoing monomers, and optionally at least one other ethylenically unsaturated monomer; the at least one other ethylenically unsaturated monomer is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and salts of the foregoing, and mixtures of the foregoing.

8. The process according to any one of claims 1 to 7, wherein the polyacid II comprises monomeric units formed from ethylenically unsaturated monomers acrylic acid, methacrylic acid and 2-methyl-2-propene-1-sulfonic acid or the corresponding salts.

9. The method of any one of claims 1 to 8, wherein in the case of options (a) and (b), the additive comprising a polyoxyalkylene group is selected from (C)₆-C₂₂) Alcohol ethoxylate, (C)₆-C₂₂) Alcohol ether sulfonate and (C)₆-C₂₂) Alcohol ether sulphate, and in the case of option (c), the additive is incorporated into the polymer as a polyoxyethylenated ethylenically unsaturated monomer.

10. A redispersible dispersion powder obtainable by the process of any one of claims 1 to 9.

11. An aqueous dispersion obtainable by step (1) of the process according to any one of claims 1 and 3 to 9.

12. A building material composition comprising

-the redispersible dispersion powder of claim 10, and/or

-the aqueous dispersion according to claim 11.

13. Use of the redispersible dispersion powder of claim 10 in building material compositions.

14. Use of the aqueous dispersion according to claim 11 for preparing a redispersible dispersion powder.

Examples

Determination of the molecular weight of the polyacid II:

samples for determining molar mass were prepared by the following method: the copolymer solution was dissolved in the GPC eluate so that the polymer concentration in the GPC eluate was 0.5 wt%. Thereafter, the solution was filtered through a syringe filter having a polyethersulfone membrane and a pore size of 0.45 μm. The injection amount of the filtrate is 50-100 μ l.

The average molecular weight was determined on a Waters GPC instrument with a UV detector (Waters 2487) and RI detector (Waters2410) under the model name Alliance 2690. The following settings and conditions were used:

column: SB-800HQ series Shodex SB-G guard column and Shodex Ohpak SB 804HQ and 802.5HQ (PHM gel, 8X 300mm, pH 4.0 to 7.5)

Eluent: 0.05M ammonium formate/methanol in water mixture 80:20 (parts by volume)

Flow rate: 0.5ml/min

Temperature: 50 deg.C

Injection amount: 50 to 100. mu.l

And (3) detection: RI and UV

The molecular weight of the copolymer was determined relative to a polyacrylic acid standard from PSS Polymer Standards Service GmbH. The molecular weight distribution curve of the polyacrylic acid standard was determined by light scattering.

Providing a polymer dispersion and a spray aid:

dispersion 1:

the dispersion comprises styrene-2-ethylhexyl acrylate copolymer, which still comprises monomer units derived from the stabilizing co-monomers hydroxyethyl methacrylate (HEMA) and 2, 3-epoxypropyl methacrylate (GMA). The solids content of the dispersion was 55% by weight. The glass transition temperature of the polymer was-15 ℃ and the particle size was about 600 nm. The dispersion also contained 0.5% by weight of (C) having a degree of ethoxylation of 18₁₆-C₁₈) Alkyl ethoxylate, 0.3% by weight of a mixture of sodium diethylhexyl sulfosuccinate/isotridecyl alcohol ethoxylate having a degree of ethoxylation of 4 and 0.1% by weight of C_12-14Alkyl (EO)₃₀SO₄Na。

Dispersion 2:

the dispersion comprises a styrene-2-ethylhexyl acrylate copolymer still comprising monomer units derived from methoxy poly (oxyethylene) methacrylate and 2, 3-epoxypropyl methacrylate (GMA) having a degree of ethoxylation of the stabilising co-monomer of 17. The solids content of the dispersion was 56.5% by weight. The polymer had a glass transition temperature of-13 ℃ and a particle size of about 510 nm. The dispersion also contains 0.5% by weight of a sulfated polyoxyethylenated C having a degree of ethoxylation of 4₁₂-C₁₄Alcohol ethoxylate and 0.3 wt% sodium lauryl sulfate.

Dispersion 3:

the dispersion comprises a styrene-butadiene copolymer which still comprises monomer units derived from the stabilising co-monomers hydroxyethyl methacrylate (HEMA) and acrylic acid. The solids content of the dispersion was 51% by weight. The polymer had a glass transition temperature of 0 ℃ and a particle size of about 160 nm. The dispersion also contains 1% by weight of C_12-14-alkanesRadical (EO)₄SO₄Na, 0.7% by weight of isotridecanol ethoxylate having a degree of ethoxylation of 4 and 0.5% by weight of isotridecanol ethoxylate having a degree of ethoxylation of 8.

Dispersion 4:

in addition to the styrene-butadiene copolymer from dispersion 3, this dispersion also contained 3% by weight (based on the solids content of the dispersion) of isotridecanol ethoxylate having a degree of ethoxylation of 25.

Spraying Assistant (SA)

Spray assistant 1:

in a reaction vessel equipped with a reflux condenser, stirrer, thermometer, dropping funnel and nitrogen purge, an initial charge of 180g of water, 94.8g of sodium methallyl sulfonate and 3g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride (Wako V50) was heated to 80 ℃. When this temperature was reached, a solution of 3g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride, 108g of acrylic acid, 129g of methacrylic acid and 150g of water was metered in over 36min while stirring at 80 to 90 ℃. The reaction solution was stirred at 80 ℃ for 1h and then cooled to room temperature. The product obtained had a solids content of 52.0% by weight, a pH of 1.4 and a molecular weight M_wAbout 2400g/mol of clear polymer solution.

Spray aid 1A:

the pH of spray aid 1A was adjusted to 2.4 with NaOH.

A spray aid 1B;

the pH of spray aid 1A was adjusted to 3.4 with NaOH.

Comparative spray aid 1C:

the pH of spray aid 1A was adjusted to 4.2 with NaOH.

Comparative spray aid 1D:

the pH of spray aid 1A was adjusted to 6.1 with NaOH.

Spray aid 1E:

by H₂SO₄The pH of the spray aid 1A was adjusted to 1.9.

Comparative spray aid 2:

in a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, a dropping funnel and a nitrogen purgeIn a vessel, an initial charge of 140g of water and 2g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride (Wako V50) was heated to 70 ℃. When this temperature was reached, a solution of 2g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride, 3g of 3-mercaptopropionic acid, 100g of acrylic acid and 100g of water was metered in over 36min while stirring at 70 to 90 ℃. The reaction solution was stirred at 80 ℃ for 1h and then cooled to room temperature. The product obtained had a solids content of 46.3% by weight, a pH of 1.4 and a molecular weight M_wA clear polymer solution of about 11600 g/mol.

Comparative spray aid 2A:

an aliquot of spray aid 2 was adjusted to pH 6.0 with NaOH.

Comparative spray aid 2B:

by H₂SO₄An aliquot of spray aid 2A was adjusted to pH 1.4.

Comparative spray aid 3:

pH of 2 and molecular weight M_wPolyacrylic acid, about 5000g/mol, manufactured by BASF and available under the trade name Sokalan PA 25 XS.

Comparative spray aid 4:

pH of-8 and molecular weight M_wPolyacrylic acid, about 8000g/mol, is manufactured by BASF and is commercially available under the trade name Sokalan PA 30.

Spraying aid 5:

in a reaction vessel equipped with a reflux condenser, stirrer, thermometer, dropping funnel and nitrogen purge, an initial charge of 200g of water, 81g of sodium methallyl sulfonate and 1.5g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride (Wako V50) was heated to 73 ℃. When this temperature was reached, a solution of 1.5g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride, 250g of methacrylic acid and 130g of water was metered in over 1h with stirring at 73 to 81 ℃. The reaction solution was stirred at 80 ℃ for 1h and then cooled to room temperature. The product obtained had a solids content of 50.3% by weight, a pH of 1.4 and a molecular weight M_wIs about 1400g/mol of clear polymer solution.

Spraying aid 6:

in a device equipped with a reflux condenser, a stirrer, a thermometer and dropping liquidIn a reaction vessel purged with funnel and nitrogen, an initial charge of 280g of water and 195g of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) was heated to 18 ℃. While stirring, 70g of 50% sodium hydroxide solution were added dropwise at 18 ℃. Subsequently, 68g of acrylic acid, 2.8g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride (Wako V50) and 4g of mercaptoethanol were metered in over 10min while stirring. The reaction solution was stirred at 70 to 80 ℃ for 1.5h, then cooled to room temperature. The product obtained had a solids content of 48.1% by weight, a pH of 0.8 and a molecular weight M_wAbout 8400g/mol of clear polymer solution.

Spray assistant 7:

an initial charge of 350g of water and 313g of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) was heated to 18 ℃ in a reaction vessel equipped with a reflux condenser, stirrer, thermometer, dropping funnel and nitrogen purge. 112g of 50% sodium hydroxide solution are added dropwise at 18 ℃ while stirring. Subsequently, 27g of acrylic acid, 2.8g of 2,2' -azobis (2-methylpropionamidine) dihydrochloride (Wako V50) and 6g of mercaptoethanol were metered in over 14min while stirring. The reaction solution was stirred at 70 to 80 ℃ for 1.5h, then cooled to room temperature. The product obtained had a solids content of 48.5% by weight, a pH of 0.8 and a molecular weight M_wA clear polymer solution of about 7400 g/mol.

Preparation of polymer powder by spray drying:

spray drying was carried out using a laboratory dryer from Niro (Niro Atomizer) with nitrogen as the drying gas. In each case, the aqueous dispersion to be dried, which comprises a water-soluble spraying aid, is sprayed through a two-phase nozzle, the solids content of the aqueous dispersion being from 40 to 60%. The inlet temperature of the dryer gas is 130 to 140 ℃; the outlet temperature is 60 to 70 ℃. The antiblocking agent used was 0.5 to 1% by weight (based on the solids content of the feed solution) of silica and 9% by weight (based on the solids content of the feed solution) of Luzenac talc (from Imerys).

Measurement of redispersibility of dispersion powders:

films were prepared using a composition consisting of the dispersion with the Spray Aid (SA) specified in table 1 and tested for their redispersibility. For this purpose, a liquid dispersion (5g of solid) in 10-15mL of water was mixed with the stated amount of the corresponding spray aid and dried overnight at 60 ℃. While stirring (200rpm) at room temperature, about 0.5g of the resulting film was dissolved in 10mL of deionized water. After a fast redispersion within a few minutes, these dispersion systems were also found to have excellent spray-drying properties and to give redispersible powders (RDP).

Redispersibility was evaluated as follows:

-complete redispersion within minutes: is very good

-almost completely redispersion within minutes: good effect

Incomplete redispersion (part of the film still clearly visible): medium and high grade

The majority of the film is insoluble or not redispersed: difference (D)

Table 1 redispersibility of redispersible dispersion powders (n.d. ═ not determined)

It was found to be advantageous for redispersibility when the pH of the dispersion is <4 and when the spray aid is a polyacid formed from at least one ethylenically unsaturated monomer containing sulfonic acid groups. Particular preference is given to using spray assistants based on at least one allyl monomer comprising at least one sulfonic acid group.

Preparation of a building material composition using a redispersible dispersion powder:

the redispersible dispersion powder of the invention was used to prepare building material compositions according to table 2. Here, example 1 is a comparative example in which a styrene-acrylate copolymer (Acronal) is used instead of a redispersible dispersion powder.

Table 2:

the pot life of the dispersion-modified mineral building material mixtures described above was evaluated. Pot life is the period of time during which the polymer-modified prefabricated building material has a viscosity and creaminess suitable for processing so that it can be applied to an application substrate using suitable auxiliary tools (trowels, spatulas, etc.). If this period is exceeded, the building material will no longer spread smoothly on the application substrate. Pot lives of 0.5-2h are satisfactory, while faster systems are difficult to process, while extremely slow systems (pot lives >3h) delay the next working step.

The dispersion-modified mineral building material mixture was used to prepare films (height: 2.0mm, width 12.0cm and length 20 to 25 cm). The dried building material was checked for appearance. It is good if it is uniform (no separation), smooth on the surface and free of irregularities and cracks (rated OK in table 3).

If the pH of the dispersion is greater than 4, processing cannot be carried out (see dispersion powder xii) in Table 3). If the spray aid does not comprise any polymer having sulfonic acid groups, processing is not possible (see dispersion powders xi) and viii) in Table 3). Furthermore, good processing is only possible if the spray aid is based on at least one allyl monomer containing at least one sulfonic acid group.

TABLE 3 Properties of the building material compositions