Method for preparing an aqueous polymer dispersion

Abstract

Aqueous polymer dispersions and their use for producing shaped articles having improved heat resistance are described.

Claims

1. A process for producing an aqueous dispersion comprising a polymer P, the process comprising: conducting a free-radically initiated aqueous emulsion polymerization of a mixture comprising ethylenically unsaturated compounds, wherein the mixture comprises 0.5 and 4.0 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic acid or dicarboxylic acid, as a monomer A, 2.0 and 8.0 wt % of at least one monoethylenically unsaturated compound having at least one epoxy group, as a monomer B, 0.1 and 1.5 wt % of at least one monoethylenically unsaturated compound having at least one sulfonic acid group, as a monomer C, 75 and 85 wt % of at least one ester obtained from vinyl alcohol and a C.sub.1 to C.sub.5 monocarboxylic acid, as a monomer D, and 0.1 and 20 wt % of at least one ethylenically unsaturated compound other than the monomers A to D, as a monomer E, and wherein the amounts of the monomers A to E sum to 100 wt %, for the polymerization.

2. The process according to claim 1, wherein the at least one monomer A is at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, 2-methylmaleic acid and itaconic acid.

3. The process according to claim 1, wherein the at least one monomer B is at least one selected from the group consisting of vinyloxirane, allyloxirane, glycidyl acrylate and glycidyl methacrylate.

4. The process according to claim 1, wherein the at least one monomer C is at least one selected from the group consisting of vinylsulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid.

5. The process according to claim 1, wherein the at least one monomer D is at least one selected from the group consisting of vinyl acetate and vinyl propionate.

6. The process according to claim 1, wherein the at least one monomer E is at least one selected from the group consisting of an olefin, a conjugated aliphatic C.sub.4 to C.sub.9 diene, an ester obtained from vinyl alcohol and a C.sub.6 to C.sub.18 monocarboxylic acid, a C.sub.1 to C.sub.10 alkyl acrylate, a C.sub.1 to C.sub.10 alkyl methacrylate, a C.sub.5 to C.sub.10 cycloalkyl acrylate, a C.sub.5 to C.sub.10 cycloalkyl methacrylate, a C.sub.1 to C.sub.10 dialkyl maleate, a C.sub.1 to C.sub.10 dialkyl fumarate, a vinylaromatic monomer, a mono- or dinitrile of an ethylenically unsaturated C.sub.3 to C.sub.6 mono- or dicarboxylic acid, and a mono- or dicarboxamide of an ethylenically unsaturated C.sub.3 to C.sub.6 mono- or dicarboxylic acid.

7. The process according to claim 1, wherein the mixture comprises 0.5 and 3.0 wt % of the at least one monomer A, 3.0 and 7.0 wt % of the at least one monomer B, 0.1 and 1.0 wt % of the at least one monomer C, 78 and 83 wt % of the at least one monomer D, and 5.0 and 15 wt % of the at least one monomer E.

8. The process according to claim 1, wherein the monomer A is acrylic acid, methacrylic acid, or both, the monomer B is glycidyl acrylate, glycidyl methacrylate, or both, the monomer C is vinylsulfonic acid, the monomer D is vinyl acetate, and the monomer E is n-butyl acrylate, 2-ethylhexyl acrylate, or both.

9. The process according to claim 1, wherein the polymer P has a glass transition temperature of 20 C. and 40 C., as determined by ISO 11357-2:2013.

10. A method of producing a composition, the method comprising: obtaining an aqueous polymer dispersion by the process according to claim 1, optionally drying the aqueous polymer dispersion, thereby obtaining a polymer powder, and producing the composition with the aqueous polymer dispersion, the polymer powder, or both, wherein the composition is at least one selected from the group consisting of a binder in the manufacture of adhesives, sealants, renders and paints, a binder in sand consolidation, a component in the manufacture of textile or leather auxiliaries and impact modifiers for modifying mineral binders and plastics.

11. A process for producing a shaped article from a substrate, the process comprising: obtaining an aqueous polymer dispersion by the process according to claim 1, applying the aqueous polymer dispersion to the substrate to form a treated substrate, and drying the treated substrate at a temperature above the glass transition temperature of the polymer P to form a shaped article, wherein the substrate is a granular substrate, a fibrous substrate, or both.

12. The process according to claim 11, wherein an amount of aqueous binder composition is present during the applying such that 1 and 100 g of the polymer P is present per 100 g of the substrate after the applying.

13. The process according to claim 11, further comprising: shaping the treated substrate after the applying of the aqueous polymer dispersion.

14. The process according to claim 1, wherein the monomer E is not ethene.

Description

EXAMPLES

(1) I Preparation of Polymers P as their Aqueous Dispersions

(2) Polymer Dispersion 1 (P1)

(3) In a 2 L glass flask fitted with a stirrer and 4 metering devices, an initial charge of 262.9 g of deionized water, 43.8 g of a 20 wt % aqueous solution of a C.sub.16C.sub.18 fatty alcohol ethoxylate (Lutensol AT 18, from BASF SE) and 12.3 mg of iron(II) sulfate heptahydrate, placed therein at 20 to 25 C. (room temperature) and under nitrogen blanketing, was heated up to 30 C. with stirring. This was followed by the simultaneous commencement of the continuous metered additions at constant flow rates of feed 1 in the form of a homogeneous aqueous emulsion and also of feeds 2 and 3 in the form of aqueous solutions for a period of 4.0 hours. Within 20 minutes of the commencement of feeds 1, 2 and 3, the temperature of the aqueous polymerization mixture was raised from 30 to 70 C.

(4) Feed 1:

(5) TABLE-US-00005 713.9 g of vinyl acetate 95.4 g of n-butyl acrylate 43.8 g of glycidyl methacrylate 17.5 g of acrylic acid 17.5 g of a 25 wt % aqueous solution of vinylsulfonate 20.5 g of a 32 wt % aqueous solution of a C.sub.12C.sub.14 alkyl polyglycol ether sulfate sodium salt (Disponil FES 77, from BASF SE) 32.8 g of a 20 wt % aqueous solution of a C.sub.16C.sub.18 fatty alcohol ethoxylate (Lutensol AT 18) 252.6 g of deionized water

(6) Feed 2:

(7) TABLE-US-00006 105.0 g of a 2.5 wt % aqueous solution of sodium peroxodisulfate

(8) Feed 3:

(9) TABLE-US-00007 43.7 g of deionized water 1.8 g of sodium acetate 1.5 g of sodium hydroxylmethylsulfonate (Rongalit C, from BASF SE)

(10) On completion of feeds 1 to 3, 68.3 g of deionized water and 13.7 g of a 32 wt % aqueous solution of C.sub.12C.sub.14 alkyl polyglycol ether sulfate sodium salt (Disponil FES 77) were added to the polymerization mixture in the course of 10 minutes by continuous metered addition at constant flow rates. The polymerization mixture was subsequently allowed to undergo secondary polymerization at 70 C. for 30 minutes. This was followed by the simultaneous commencement of the continuous metered additions at constant flow rates and constant temperature of 21.0 g of a 10 wt % aqueous solution of tert-butyl hydroperoxide and 29.4 g of a 13.1 wt % aqueous solution of acetone bisulfite (1:1 addition product of acetone and sodium hydrogensulfite) over one hour for the purpose of residual monomer removal. The aqueous polymer dispersion was subsequently cooled down to room temperature and then admixed with 5.3 g of a 7.5 wt % aqueous solution of Acticid MBS and also 1.6 g of a 1.5 wt % aqueous solution of Acticid MV (product from Thor GmbH). pH 5.0 was set by admixture of 10 wt % aqueous sodium hydroxide solution. The aqueous polymer dispersion obtained was finally filtered through a 500 m filter.

(11) The aqueous polymer dispersion thus obtained had a solids content of 50.7 wt % based on the total weight of the aqueous dispersion. The number average corpuscle diameter was found to be 169 nm. The glass transition temperature of the polymer was found to be 34.2 C.

(12) Solids contents were generally determined by drying a defined amount of the aqueous polymer dispersion (about 0.8 g) using the HR73 moisture determinator from Mettler Toledo at a temperature of 130 C. to constant weight (for about 2 hours). Two measurements were carried out in each case. The value reported in each case is the average of these measurements.

(13) Number average corpuscle diameters for the polymer corpuscles were generally determined by dynamic light scattering on a 0.005 to 0.01 weight percent aqueous polymer dispersion at 23 C. using an Autosizers 110 from Malvern Instruments, England. The reported value is the cumulant z-average of the measured autocorrelation function (ISO standard 13321).

(14) The general procedure for determining their glass transition temperature was to apply the aqueous polymer dispersions in a thickness of about 1 mm to a Teflon foil and to dry the resulting films at 23 C. and 50% relative humidity (standard conditions) for 24 hours. The glass transition temperature was generally determined using a Q 2000 differential scanning calorimeter from TA Instruments. The polymer films obtained were typically used at an initial weight of about 8.5 mg. Heating rate was 20 K per minute. The second heating curve in each case was detected and evaluated according to the mandates of ISO 11357-2.

(15) Comparative Dispersion 1 (V1)

(16) V1 was prepared similarly to P1 except that 112.9 g of n-butyl acrylate were used in feed 1 instead of 95.4 g. Nor was any acrylic acid used.

(17) The aqueous comparative dispersion obtained had a solids content of 50.7 wt % based on the total weight of the aqueous dispersion. The number average corpuscle diameter was found to be 129 nm and the glass transition temperature 28.4 C.

(18) Comparative Dispersion 2 (V2)

(19) V2 was prepared similarly to P1 except that 99.8 g of n-butyl acrylate were used in feed 1 instead of 95.4 g. Nor was any vinylsulfonic acid used.

(20) The aqueous comparative dispersion obtained had a solids content of 50.3 wt % based on the total weight of the aqueous dispersion. The number average corpuscle diameter was found to be 184 nm and the glass transition temperature 33.1 C.

(21) Comparative Dispersion 3 (V3)

(22) V3 was prepared similarly to P1 except that 130.4 g of n-butyl acrylate and 26.3 g of acrylic acid were used in feed 1 instead of 95.4 g and 17.5 g, respectively. Nor was any glycidyl methacrylate used.

(23) The aqueous comparative dispersion obtained had a solids content of 50.8 wt % based on the total weight of the aqueous dispersion. The number average corpuscle diameter was found to be 194 nm and the glass transition temperature 28.7 C.

(24) Comparative Dispersion 4 (V4)

(25) V4 was prepared similarly to P1 except that feed 1 utilized 495.3 g of methyl methacrylate and 713.9 g of vinyl acetate and 314.0 g of n-butyl acrylate instead of 95.4 g. No vinyl acetate was used.

(26) The polymerization had to be discontinued after 2 hours and 15 minutes on account of noticeable fouling.

(27) II Production of Bonded Fiber Webs and Performance Testing

(28) Bonded fiber webs were produced from a base web comprising a needled polyethylene terephthalate spunbonded (400 cm length, 40 cm width) having a basis weight of 125 g/m.sup.2.

(29) Binder liquors were produced by diluting aqueous polymer dispersion P1 and also comparative dispersions Vito V3 with deionized water to a solids content of 13 wt %. In what follows, the binder liquors obtained are referred to as binder liquors BP1 and also BV1 to BV3.

(30) The base webs producing the bonded fiber webs were drenched with the respective binder liquor BP1 and also BV1 to BV3 in the machine direction in an HVF impregnator with pad-mangle from Mathis (rubber roll Shore A=85/steel roll). The wet pickup was in each case adjusted to 192.3 g of binder liquor per square meter (corresponding to a solids add-on of 25 g/m.sup.2). The impregnated fiber webs obtained were subsequently dried and bonded in a Fleissner industrial dryer at 200 C. for 3 minutes. The bonded fiber webs obtained on cooling down to room temperature are referred to as fiber webs F1 and also FV1 to FV3 in accordance with the binder liquors used.

(31) Determination of Heat Resistance

(32) The heat resistance of fiber webs F1 and FV1 to FV3 was determined on the lines of DIN 18192 by measuring the extension in the machine direction and the shrinkage in the cross direction at 200 C. To this end, 100360 mm strips were die-cut out of the fiber webs in the machine direction. Marks were made in the center on each of the fiber web strips at points respectively located 130 mm away from the two narrow sides, the marks defining a measuring sector of 1000.2 mm there between. In the middle of the measuring sector the width of the fiber web strip was checked by measurement. Thereafter, the narrow ends were fixed in clamping rails such that a clamped length of 300 mm arose. Concurrently therewith, the tripod required for measurement and also a stainless steel cylinder 4 kg in weight were heated to 200 C. in a drying cabinet. To perform the test, then, the marked and measured fiber web strips were attached with one of the clamping rails to the tripod in the drying cabinet to hang down freely.

(33) The 4 kg stainless steel cylinder was then suspended from the lower clamping rail, the door of the drying cabinet was closed and the fiber web thus clamped was left at 200 C. in the drying cabinet for 10 minutes. Thereafter, the laboratory tripod together with the weighted fiber web strip was taken from the drying cabinet and left to cool down at room temperature for 5 minutes. Thereafter, the stainless steel cylinder was first taken off the lower clamping rail and then the upper clamping rail was taken off the tripod (the tripod and the stainless steel cylinder were put back in the drying cabinet for conditioning for the next measurement). After the upper and lower clamping rails had been removed, the fiber web strip was laid flat on the laboratory table and the respective distance between the two applied marks (in the machine direction) and also the respective width at the narrowest place (in the cross direction) of the fiber web strips were measured. In each case, measurements were carried out on 9 separate measuring strips. The values reported in table 1 represent the averages of these measurements. The lower the extension in the machine direction and the lower the shrinkage in the cross direction, the better the results. The reported particulars are the change in the machine or cross direction in percent, based on the corresponding distances before the thermal/mechanical treatment.

(34) TABLE-US-00008 TABLE 1 Results of heat resistance test at 200 C. Extension Shrinkage Fiber web [in %] [in %] F1 3.9 5.6 FV1 >10 <15 FV2 5.6 8.3 FV3 >10 <15

(35) It is clearly apparent from the results that the fiber web produced using the inventive binder liquor BP1 has improved heat resistance at 200 C. compared with binder liquors BV1 to BV3.