PROCESS FOR PREPARING AN AQUEOUS POLYMER DISPERSION

Abstract

A process for preparing an aqueous dispersion of a polymer P (aqueous polymer P dispersion) by free-radically initiated aqueous emulsion polymerization.

Claims

1: A process for preparing an aqueous dispersion of a polymer P, the process comprising: conducting a free-radically initiated aqueous emulsion polymerization, which comprises polymerizing >3% and 8% by weight of a monomer A, comprising: a monoethylenically unsaturated compound having at least one epoxy group and/or one N-methylol group and/or a compound having at least two nonconjugated ethylenically unsaturated groups, and 92% and <97% by weight of a monomer B, comprising: an ethylenically unsaturated compound different from the monomer A, wherein a polymer formed solely from the ethylenically unsaturated compound in polymerized form have a glass transition temperature of 0 C. and 50 C., wherein amounts of the monomers A and B add up to 100% by weight, in the presence of 25% and 120% by weight of at least one lignin compound L, based on the total amount of monomers, and wherein the monomer B does not include any ethylenically unsaturated C.sub.3 to C.sub.6 monocarboxylic acids and/or C.sub.4 to C.sub.6 dicarboxylic acids and salts and anhydrides thereof or monoethylenically unsaturated compounds having at least one silicon-containing group, a hydroxyalkyl group or a carbonyl group.

2: The process according to claim 1, wherein the monomer A is at least one selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, glycidyl acrylate, glycidyl methacrylate, butylene glycol 1,4-diacrylate, allyl methacrylate and divinylbenzene.

3: The process according to claim 1, wherein the monomer B is selected from the group consisting of a conjugated aliphatic C.sub.4 to C.sub.9 diene, an ester of vinyl alcohol and a C.sub.1 to C.sub.10 monocarboxylic acid, a C.sub.1- to C.sub.10-alkyl acrylate, a C.sub.1- to C.sub.10-alkyl methacrylate, an ethylenically unsaturated C.sub.3 to C.sub.6 monocarbonitrile, an ethylenically unsaturated C.sub.4 to C.sub.6 dicarbonitrile, a C.sub.5- to C.sub.10-cycloalkyl acrylate and a methacrylate, a C.sub.1- to C.sub.10-dialkyl maleate and a C.sub.1- to C.sub.10-dialkyl fumarate and a vinylaromatic monomer.

4: The process according to claim 1, wherein the polymerizing comprises polymerizing: 3.5% and 7% by weight of the monomer A, and 93% and 96.5% by weight of the monomer B.

5: The process according to claim 1, wherein the polymerizing comprises polymerizing: 3.5% and 5.5% by weightof the monomer A, which is at least one selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, glycidyl acrylate, glycidyl methacrylate, butylene glycol 1,4-diacrylate, allyl methacrylate and divinylbenzene, and 94.5% and 96.5% by weight of the monomer B, which is at least one selected from the group consistingof 2-ethylhexyl acrylate, n-butyl acrylate, acrylonitrile, 1,4-butadiene, ethyl acrylate, vinyl acetate, methyl methacrylate, styrene and tert-butyl methacrylate.

6: The process according to claim 1, wherein the at least one lignin compound L is a lignosulfonate.

7: The process according to claim 1, wherein the at least one lignin compound L is present at 30 and 80 parts by weight.

8: An aqueous polymer P dispersion obtained by the process according to claim 1.

9: A binder for at least one granular and/or fibrous substrate, comprising the aqueous polymer P dispersion of claim 8.

10: A process for producing a shaped body from at least one granular and/or fibrous substrate, the process comprising: applying an aqueous binder composition comprising, as an essential component, the aqueous polymer P dispersion according to claim 8 to the at least one granular and/or fibrous substrate, optionally shaping the at least one granular and/or fibrous substrate thus treated, and subjecting the at least one granular and/or fibrous substrate thus obtained to a thermal treatment at a temperature of 110 C.

11: The process according to claim 10, wherein an amount of the aqueous binder composition is chosen such that 1 and 100 g of a binder, which corresponds to the sum of the total amounts of the polymer P and the at least one lignin compound L, are applied per 100 g of the at least one granular and/or fibrous substrate.

12: A shaped body obtained by the process according to claim 10.

13: A process for producing a bituminized roofing membrane, the process comprising: producing the bituminized roofing membrane with the shaped body according to claim 12.

14: A bituminized roofing membrane produced by the process according to claim 13.

Description

EXAMPLES

Polymer Dispersion D1

[0103] A 2 L polymerization vessel equipped with a stirrer, a reflux condenser and metering devices was initially charged, under a nitrogen atmosphere, with 366.9 g of a 47.7% by weight aqueous calcium lignosulfonate solution (Bretax CL, product from the Burgo Group), 73.7 g of deionized water and 8.3 g of a 15% by weight solution of a fatty alcohol sulfate (Disponil SDS 15; product from BASF SE). The initially charged mixture was heated to 70 C. while stirring, then the monomer feed, the N-methylolacrylamide feed and the initiator feeds were started simultaneously and metered in over 120 minutes, each at constant flow rates, while maintaining the temperature. The monomer feed consisted of 120.0 g of styrene, 117.5 g of n-butyl acrylate and 2.5 g of butylene glycol 1,4-diacrylate. The N-methylolacrylamide feed consisted of 28.6 g of a 35% by weight aqueous solution of N-methylolacrylamide and 9.4 g of deionized water. The first initiator feed consisted of 75.0 g of a 10% by weight aqueous tert-butyl hydroperoxide solution, and the second initiator feed of 57.0 g of a 10% by weight aqueous solution of sodium hydroxymethylsulfinate (Rongalit C; product from BASF SE).

[0104] After the feeds had ended, the polymerization mixture was stirred at 70 C. for another 1 hour. Thereafter, 25.0 g of a 10% by weight aqueous tert-butyl hydroperoxide solution were metered in at constant flow rate within 30 minutes, and then the polymerization mixture was stirred at 70 C. for another 90 minutes. Subsequently, the aqueous polymer dispersion obtained was cooled down to 20 to 25 C. (room temperature).

[0105] The polymer dispersion D1 thus produced had a solids content of 47.8% by weight and an LD value of 78%. A bimodal particle size distribution with one maximum each at 85 and 300 nm was measured.

[0106] The solids contents were generally determined by drying a defined amount of the respective aqueous polymer dispersion (about 5 g) to constant weight at 140 C. in a drying cabinet. Two separate measurements were conducted in each case. The value reported in each case is the mean of these two measurements.

[0107] A measure of the particle size of the dispersed polymer particles is the LD value. To determine the LD value (transparency), the polymer dispersion to be examined in each case is analyzed in 0.1% by weight aqueous dilution in a cuvette having an edge length of 2.5 cm with light of wavelength 600 nm and compared with the corresponding transparency of deionized water under the same test conditions. The transparency of deionized water was assumed here to be 100%. The finer the dispersion, the higher the LD value which is measured by the method described above. The measurements can be used to calculate the average particle size; cf. B. Verner, M. Brta, B. Sedlcek, Tables of Scattering Functions for Spherical Particles, Prague, 1976, Edice Marco, Rada D-DATA, SVAZEK D-1.

[0108] The number-average particle diameters of the polymer particles were generally determined by dynamic light scattering on a 0.005 to 0.01 percent by weight aqueous polymer dispersion at 23 C. using an Autosizer IIC from Malvern Instruments, England. What is reported is the cumulant z-average diameter of the measured autocorrelation function (ISO Standard 13321).

Polymer Dispersion D2

[0109] Polymer dispersion D2 was produced entirely analogously to the production of polymer dispersion D1, except that 314.5 g rather than 366.9 g of the 47.7% by weight aqueous calcium lignosulfonate solution and 101.1 g rather than 73.7 g of deionized water were used.

[0110] The polymer dispersion D1 thus produced had a solids content of 48.1% by weight and an LD value of 74%. A bimodal particle size distribution with one maximum each at 250 and 935 nm was measured.

Polymer Dispersion D3

[0111] Polymer dispersion D3 was produced entirely analogously to the production of polymer dispersion D1, except that 209.6 g rather than 366.9 g of the 47.7% by weight aqueous calcium lignosulfonate solution and 156.0 g rather than 73.7 g of deionized water were used.

[0112] The polymer dispersion D1 thus produced had a solids content of 48.4% by weight and an LD value of 63%. A bimodal particle size distribution with one maximum each at 110 and 360 nm was measured.

Polymer Dispersion D4

[0113] A 1.5 L polymerization vessel equipped with a stirrer, a reflux condenser and metering devices was initially charged, under a nitrogen atmosphere, with 293.5 g of a 47.7% by weight aqueous calcium lignosulfonate solution (Bretax CL, product from the Burgo Group), 36.8 g of deionized water and 6.7 g of a 15% by weight solution of a fatty alcohol sulfate (Disponil SDS 15). The initially charged mixture was heated to 70 C. while stirring, then the monomer feed and the initiator feeds were started simultaneously and metered in over 120 minutes, each at constant flow rates, while maintaining the temperature. The monomer feed consisted of 96.0 g of styrene, 96.0 g of n-butyl acrylate, 6.0 g of glycidyl methacrylate and 2.0 g of butylene glycol 1,4-diacrylate. The first initiator feed consisted of 60.0 g of a 10% by weight aqueous tert-butyl hydroperoxide solution, and the second initiator feed of 45.6 g of a 10% by weight aqueous solution of sodium hydroxymethylsulfinate (Rongalit C). After the feeds had ended, a further 38.3 g of deionized water were added to the polymerization mixture and then the polymerization mixture was stirred at 70 C. for another 1 hour. Thereafter, 20.0 g of a 10% by weight aqueous tert-butyl hydroperoxide solution were metered in at constant flow rate within 30 minutes. Subsequently, another 10.3 g of deionized water were added and then the polymerization mixture was stirred at 70 C. for another 90 minutes. Subsequently, the aqueous polymer dispersion obtained was cooled down to room temperature.

[0114] The polymer dispersion D4 thus produced had a solids content of 49.2% by weight and an LD value of 78%. A bimodal particle size distribution with one maximum each at 105 and 240 nm was measured.

Polymer Dispersion D5

[0115] Polymer dispersion D5 was produced entirely analogously to the production of polymer dispersion D4, except that 251.6 g rather than 293.5 g of the 47.7% by weight aqueous calcium lignosulfonate solution and 58.7 g rather than 36.8 g of deionized water were used.

[0116] The polymer dispersion D5 thus produced had a solids content of 49.7% by weight and an LD value of 72%. The number-average particle diameter was determined as 265 nm.

Polymer Dispersion D6

[0117] Polymer dispersion D6 was produced entirely analogously to the production of polymer dispersion D4, except that 167.7 g rather than 293.5 g of the 47.7% by weight aqueous calcium lignosulfonate solution and 102.6 g rather than 36.8 g of deionized water were used.

[0118] The polymer dispersion D6 thus produced had a solids content of 49.1% by weight and an LD value of 55%. A bimodal particle size distribution with one maximum each at 85 and 340 nm was measured.

Polymer Dispersion D7

[0119] Polymer dispersion D7 was produced entirely analogously to the production of polymer dispersion D1, except that the monomer feed consisted of 120.0 g of styrene and 117.5 g of n-butyl acrylate, and the N-methylolacrylamide feed of 35.7 g of a 35% by weight aqueous solution of N-methylolacrylamide and 9.4 g of deionized water.

[0120] The polymer dispersion D6 thus produced had a solids content of 48.0% by weight and an LD value of 76%. A bimodal particle size distribution with one maximum each at 95 and 235 nm was measured.

Polymer Dispersion D8

[0121] Polymer dispersion D8 was produced entirely analogously to the production of polymer dispersion D4, except that the monomer feed consisted of 96.0 g of styrene, 96.0 g of n-butyl acrylate and 8.0 g of glycidyl methacrylate.

[0122] The polymer dispersion D8 thus produced had a solids content of 49.0% by weight and an LD value of 75%. A bimodal particle size distribution with one maximum each at 90 and 300 nm was measured.

Polymer Dispersion D9

[0123] Polymer dispersion D9 was produced entirely analogously to the production of polymer dispersion D4, except that the monomer feed consisted of 97.0 g of styrene, 97.0 g of n-butyl acrylate and 6.0 g of butylene glycol 1,4-diacrylate.

[0124] The polymer dispersion D9 thus produced had a solids content of 48.9% by weight and an LD value of 77%. A bimodal particle size distribution with one maximum each at 100 and 245 nm was measured.

Comparative Dispersion C1

[0125] Comparative dispersion C1 was produced entirely analogously to the production of polymer dispersion D1, except that 4.5 g of an aqueous polystyrene seed latex (solids content 33% by weight; having a weight average particle diameter of 28 nm) and 444.4 g of a 2.0% by weight solution of a fatty alcohol sulfate (Disponil SDS 15) were used as initial charge.

[0126] The dispersion polymer coagulated about 30 minutes after addition of the 25.0 g of a 10% by weight aqueous tert-butyl hydroperoxide solution.

Comparative Dispersion C2

[0127] Comparative dispersion C2 was produced entirely analogously to the production of polymer dispersion D4, except that 3.6 g of an aqueous polystyrene seed latex (solids content 33% by weight; having a weight average particle diameter of 28 nm) and 333.4 g of a 2.0% by weight solution of a fatty alcohol sulfate (Disponil SDS 15) were used as initial charge.

[0128] The lignosulfonate-free comparative dispersion C2 thus produced had a solids content of 30.4% by weight and an LD value of 63%. The number-average particle diameter was determined as 155 nm.

Comparative Dispersion C3

[0129] Comparative dispersion C3 was produced entirely analogously to the production of polymer dispersion D4, except that the monomer feed consisted of 95.0 g of styrene, 95.0 g of n-butyl acrylate, 6.0 g of glycidyl methacrylate, 2.0 g of butylene glycol 1,4-diacrylate and 2.0 g of acrylic acid.

[0130] The comparative dispersion C3 thus produced had a solids content of 49.8% by weight and an LD value of 62%. A bimodal particle size distribution with one maximum each at 80 and 330 nm was measured.

Comparative Dispersion C4

[0131] Comparative dispersion C4 was produced entirely analogously to the production of polymer dispersion D4, except that the monomer feed consisted of 98.0 g of styrene, 98.0 g of n-butyl acrylate, 2.0 g of glycidyl methacrylate and 2.0 g of butylene glycol 1,4-diacrylate.

[0132] The comparative dispersion C4 thus produced had a solids content of 50.1% by weight and an LD value of 68%. A bimodal particle size distribution with one maximum each at 105 and 355 nm was measured.

Comparative Dispersion C5

[0133] Comparative dispersion C5 was produced entirely analogously to the production of polymer dispersion C3, except that 48.0 g of deionized water and 3.6 g of an aqueous polystyrene seed latex (solids content 33% by weight; having a weight average particle diameter of 28 nm) were initially charged, the monomer feed was in the form of a homogeneous aqueous emulsion consisting of 103 g of deionized water, 26.7 g of a 15% by weight aqueous solution of a fatty alcohol sulfate (Disponile SDS 15), 95.0 g of styrene, 95.0 g of n-butyl acrylate, 6.0 g of glycidyl methacrylate, 2.0 g of butylene glycol 1,4-diacrylate and 2.0 g of acrylic acid, the initiator feed 1 used was 16.3 g of a 7% by weight aqueous sodium peroxodisulfate solution, and the residual monomers were removed by means of 4.0 g of a 10% by weight aqueous solution of tert-butyl hydroperoxide and 5.0 g of a 13.1% by weight aqueous solution of acetone bisulfite (1:1 addition product of acetone and sodium hydrogensulfite).

[0134] The comparative dispersion C5 thus produced had a solids content of 50.0% by weight and an LD value of 63%. The number-average particle diameter was determined as 155 nm.

II Performance Studies

[0135] For production of the bound fiber webs, the raw web used was a needled polyethylene terephthalate spun bonded web (length 400 cm, width 40 cm) having a basis weight of 155 g/m.sup.2.

[0136] For production of the binder liquors, portions of the aqueous polymer dispersions D1 to D9 and the comparative dispersions C2 to C5 were diluted with deionized water to a solids content of 15% by weight. The binder liquors obtained are referred to hereinafter as binder liquors BD1 to BD9 and BC2 to BC5.

[0137] In addition, portions of the comparative dispersion C2 were mixed with a 47.7% by weight calcium lignosulfonate solution (Bretax CL) so as to obtain mixtures wherein the ratio of dispersion polymer to calcium lignosulfonate was 100/70, 100/60 and 100/40. These mixtures were likewise diluted with deionized water to a solids content of 15% by weight. The binder liquors thus obtained are referred to hereinafter as binder liquors BC2-1 to BC2-3.

[0138] To produce the bound fiber webs, the raw webs were soaked in a Mathis HVF impregnation system with pad mangle (rubber roll Shore A=85/steel roll) in longitudinal direction with the respective binder liquor binder liquors BD1 to BD9, BC2 to BC5 and BC2-1, BC2-2 and BC2-3. In each case, the wet pickup was adjusted to 166.7 g of binder liquor per square meter (corresponding to a solids content of 25 g/m.sup.2). Subsequently, the impregnated fiber webs obtained were dried and cured in a Fleissner industrial drier at 200 C. for 3 minutes. The bound fiber webs obtained after cooling to room temperature are referred to, depending on the binder liquors used, as fiber webs F1 to F9 and FC2 to FC5 and FC2-1, FC2-2, FC2-3.

[0139] The bound fiber webs F1 to F9 and FC2 to FC5 and FC2-1, FC2-2, FC2-3 were used to conduct the following measurements: tensile force at 180 C. and 15% elongation, thermal dimensional stability at 200 C. and elongation at 180 C. and 40 N/5 cm.

Tensile Force at 180 C. and 15% Elongation, and Elongation at a Tensile Force of 40 N/5 cm

[0140] The determinations were effected by means of a ultimate tensile strength machine from Zwick (model: Z10) with integrated equilibration chamber. For this purpose, 50210 mm strips (longitudinal direction) were punched out of the fiber webs F1 to F9 and FC2 to FC5 and FC2-1, FC2-2, FC2-3 in longitudinal direction and clamped in the pulling device with a clamped length of 100 mm. After introduction into the equilibration chamber, the respective test strip was equilibrated at 180 C. for 60 seconds and then elongated with rising tensile force at this temperature with a pulling speed of 150 mm/min. On attainment of a tensile force of 40 N/5 cm, the elongation of the test strips in percent was determined. In addition, on attainment of an elongation of the test strip of 15%, the respective tensile force in N/5 cm was determined. The results obtained are listed in table 1. The lower the elongation obtained or the higher the respective tensile force, the better the assessment of the results obtained. 5 separate measurements were conducted in each case. The values reported in table 1 are the averages of these measurements.

Shrinkage in Transverse Direction at 200 C.

[0141] Shrinkage in transverse direction at 200 C. was determined in accordance with DIN 18192. For this purpose, 100340 mm strips were punched out of the fiber webs F1 to F9 and FC2 to FC5 and FC2-1, FC2-2, FC2-3 in longitudinal direction. Proceeding in each case from the two narrow ends, at a distance of 120 mm in each case, the fiber web strips were marked in the middle, giving a measurement distance between the marks of 100 mm. In the region of the middle of this measurement distance, the width of the fiber web strip was monitored by measurement. Thereafter, the narrow ends were clamped in clamping rails.

[0142] In parallel, in a drying cabinet, the clamp stand required for the measurement and a stainless steel cylinder of weight 4 kg were heated to 200 C. For testing, the marked and measured fiber web strips were then mounted hanging by means of one clamping rail on the clamp stand within the drying cabinet. Thereafter, the stainless steel cylinder of weight 4 kg was hung on the lower clamping rail, the drying cabinet door was closed, and the fiber web thus clamped was left in the drying cabinet at 200 C. for 10 minutes. Thereafter, the laboratory clamp stand along with the weighted fiber web strip was taken out of the drying cabinet and cooled down at room temperature for 5 minutes. Thereafter, first the stainless steel cylinder was removed from the lower clamping rail and then the upper clamping rail was removed from the clamp stand (the clamp stand and stainless steel cylinder were put back into the drying cabinet for equilibration for the next measurement). After the upper and lower clamping rails had been removed, the fiber web strip was placed flat onto the laboratory bench and the respective distance at the narrowest point in transverse direction of the fiber web strips was measured. Measurements were conducted on 6 separate measurement strips in each case. The values likewise reported in the table are the averages of these measurements. The smaller the shrinkage in transverse direction, the better the assessment of the results. What is reported is the change in transverse direction in percent, based on the corresponding distances before the thermal treatment.

TABLE-US-00003 TABLE 1 Measurement results for the performance tests conducted Tensile force at Elongation at Shrinkage in 180 C. and 180 C. and transverse direction 15% elongation 40 N/5 cm at 200 C. Fiber web [N/5 cm] [%] [%] F1 71 4.0 2.1 F2 65 4.6 1.7 F3 68 4.7 2.5 F4 70 4.5 2.9 F5 69 4.8 3.0 F6 76 4.9 3.4 F7 68 4.2 2.3 F8 67 4.7 3.1 F9 66 4.6 3.2 FC2 55 9.0 12.8 FC2-1 47 8.0 10.1 FC2-2 54 6.0 7.7 FC2-3 56 6.0 7.7 FC3 58 5.5 4.3 FC4 51 6.0 5.0 FC5 50 10.8 14.0

[0143] It is clearly evident from the results that the fiber webs bonded using the binder compositions of the invention exhibit distinctly elevated tensile force values at an elongation of 15%, lower elongation at a tensile force of 40 N/5 cm, and lower shrinkage in transverse direction.