Aqueous binders for granular and/or fibrous substrates

Abstract

The present disclosure relates to an aqueous binder composition, comprising a) at least one polymer P constructed from 0.1 and 2.5 wt % of at least one acid-functional ethylenically unsaturated monomer (monomers A) 0 and 4.0 wt % of at least one ethylenically unsaturated carboxylic acid nitrile or dinitrile (monomers B) 0 and 2.0 wt % of at least one crosslinking monomer having two or more nonconjugated ethylenically unsaturated groups (monomers C) 0 and 10 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 mono- or dicarboxamide (monomers D) 25 and 69.9 wt % of at least one ethylenically unsaturated monomer whose homopolymer has a glass transition temperature 30 C. and which differs from the monomers A to D (monomers E), and 30 and 70 wt % of at least one ethylenically unsaturated monomer whose homopolymer has a glass transition temperature 50 C. and which differs from the monomers A to D (monomers F), in polymerized form, wherein the amounts of monomers A to F sum to 100 wt %, and b) at least one saccharide compound S, the amount of which is determined such that it is 10 and 400 parts by weight per 100 parts by weight of polymer P.

Claims

1. An aqueous binder composition, comprising a) at least one polymer P constructed from 0.1 and 2.5 wt % of at least one acid-functional ethylenically unsaturated monomer (monomers A) 0 and 4.0 wt % of at least one ethylenically unsaturated carboxylic acid nitrile or dinitrile (monomers B) 0.1 and 2.0 wt % of at least one crosslinking monomer having two or more nonconjugated ethylenically unsaturated groups (monomers C) 0 and 10 wt % of at least one ,-monoethylenically unsaturated C.sub.3 to C.sub.6 mono- or dicarboxamide (monomers D) 25 and 69.9 wt % of at least one ethylenically unsaturated monomer whose homopolymer has a glass transition temperature 30 C. and which differs from the monomers A to D (monomers E), and 30 and 70 wt % of at least one ethylenically unsaturated monomer whose homopolymer has a glass transition temperature 50 C. and which differs from the monomers A to D (monomers F), in polymerized form, wherein the amounts of monomers A to F sum to 100 wt %, and b) at least one saccharide compound S, the amount of which is determined such that it is 10 and 400 parts by weight per 100 parts by weight of polymer P, wherein a total amount of the saccharide compound S is added to an aqueous dispersion of the polymer P on completion of an emulsion polymerization forming the polymer P.

2. The aqueous binder composition according to claim 1, wherein: the at least one monomer E is selected from the group consisting of a conjugated aliphatic C.sub.4 to C.sub.9 diene compound, an ester of a 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.5 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 ethacrylate, a C.sub.1 to C.sub.10 dialkyl maleinate, and a C.sub.1 to C.sub.10 dialkyl fumarate; and the at least one monomer F is selected from the group consisting of a vinylaromatic monomer and a C.sub.1 to C.sub.4 alkyl methacrylate.

3. The aqueous binder composition according to claim 1, wherein the polymer P comprises 0.1 and 1.5 wt % of at least one monomer C in polymerized form.

4. The aqueous binder composition according to claim 1, wherein the polymer P is in the form of an aqueous polymer dispersion.

5. The aqueous binder composition according to claim 4, wherein the polymer particles of the aqueous polymer dispersion have a number average particle diameter 50 and 400 nm.

6. The aqueous binder composition according to claim 1, wherein the polymer P is constructed from 0.5 and 2.0 wt % of at least one monomer A 0.1 and 1.5 wt % of at least one monomer C 0 and 4.0 wt % of at least one monomer D 30 and 60 wt % of at least one monomer E, and 40 and 70 wt % of at least one monomer F.

7. The aqueous binder composition according to claim 1, wherein the polymer P is constructed from: 1.0 and 2.0 wt % of acrylic acid, methacrylic acid, itaconic acid, or a mixture thereof; 0.3 and 1.2 wt % of 1,4-butylene glycol diacrylate, allyl methacrylate, divinylbenzene, or a mixture thereof; 0 and 4.0 wt % of acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, or a mixture thereof; 30 and 50 wt % of 2-ethylhexyl acrylate, n-butyl acrylate, 1,4-butadiene, ethyl acrylate, or a mixture thereof; and 40 and 60 wt % of methyl methacrylate, styrene, tert-butyl methacrylate, or a mixture thereof.

8. The aqueous binder composition according to claim 1, wherein the polymer P is constructed from a combination of monomers comprising the monomers A, C, E, F and optionally B and D, such that a polymer consisting of the monomers A, E, F and optionally B and D in polymerized form has a glass transition temperature of 5 and 35 C.

9. The aqueous binder composition according to claim 1, wherein the at least one saccharide compound S comprises starch, cellulose, guaran, xanthan, alginate, pectin, chitosan, gum arabic, gellan, or a mixture thereof.

10. The aqueous binder composition according to claim 1, wherein the at least one saccharide compound S is a starch, a starch derivative, a substitution product of a starch, a substitution product of a starch derivative, or a mixture thereof.

11. The aqueous binder composition according to claim 1, wherein the saccharide compound S has a weight average molecular weight 5000 and 25 000 g/mol.

12. The aqueous binder composition according to claim 1, comprising 10 and 70 parts by weight of the S saccharide compound S per 100 parts by weight of the polymer P.

13. The aqueous binder composition according to claim 1, further comprising 1 wt % of a polyol compound having a molecular weight of 200 g/mol with two or more hydroxyl groups, based on the summed overall amounts of the polymer P and the saccharide compound S.

14. The aqueous binder composition according to claim 1, wherein the polymer P comprises 0.5 and 4.0 wt % of the monomer B in polymerized form.

15. The aqueous binder composition according to claim 1, wherein the polymer P comprises: 0.1 and 2.0 wt % of the monomer C in polymerized form; and 0.1 and 10 wt % of the monomer D in polymerized form.

Description

EXAMPLES

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

(2) Comparative Polymer Dispersion V1

(3) In a 2 l glass flask fitted with a stirrer and 4 metering devices, 429 g of deionized water and 19.5 g of a 33 wt % aqueous polystyrene seed dispersion (average particle diameter 32 nm) were initially charged at 20 to 25 C. (room temperature) and under nitrogen and heated to 90 C. under agitation. This was followed by the metered addition, commenced at the same time, of feed 1 in the form of an aqueous emulsion over a period of 3.5 hours and feed 2 in the form of an aqueous solution over a period of 4 hours at continuously constant flow rates while maintaining the aforementioned temperature.

(4) TABLE-US-00001 Feed 1: 16.0 g of acrylic acid 4.0 g of allyl methacrylate 622 g of styrene 142 g of n-butyl acrylate 45.7 g of a 35 wt % aqueous solution of N-methylolacrylamide 17.8 g of a 45 wt % aqueous solution of an alkylarylsulfonic acid mixture (Dowfax 2A1) 192 g of deionized water Feed 2: 85.0 g of deionized water 6.4 g of sodium persulfate

(5) The polymerization mixture was subsequently allowed to undergo secondary polymerization at 90 C. for 30 minutes and cooled down to room temperature. A pH value of 7.0 was set by addition of 25 wt % aqueous sodium hydroxide solution. The aqueous polymer dispersion obtained had a solids content of 49.4 wt % based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 149 nm.

(6) 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 (about 2 hours). Two measurements were carried out in each case. The value reported in each case is the average value of these measurements.

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

(8) Comparative Polymer Dispersion V2

(9) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 622 g instead of 142 g of n-butyl acrylate and 142 g instead of 622 g of styrene.

(10) The aqueous polymer dispersion obtained had a solids content of 49.4% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 162 nm.

(11) Comparative Polymer Dispersion V3

(12) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 366 g instead of 142 g of n-butyl acrylate, 378 g instead of 622 g of styrene and 24.0 g instead of 4.0 g of allyl methacrylate.

(13) The aqueous polymer dispersion obtained had a solids content of 49.6% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 129 nm.

(14) Comparative Polymer Dispersion V4

(15) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 606 g instead of 622 g of styrene and 32.0 g instead of 16.0 g of acrylic acid.

(16) The aqueous polymer dispersion obtained had a solids content of 49.1% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 155 nm.

(17) Comparative Polymer Dispersion V5

(18) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 133 instead of 142 g of n-butyl acrylate, 583 g instead of 622 g of styrene and additionally 48.0 of acrylonitrile.

(19) The aqueous polymer dispersion obtained had a solids content of 49.8% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 165 nm.

(20) Inventive Polymer Dispersion K1

(21) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 376 g instead of 142 g of n-butyl acrylate and 388 g instead of 622 g of styrene.

(22) The aqueous polymer dispersion obtained had a solids content of 49.6% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 156 nm.

(23) Inventive Polymer Dispersion K2

(24) In a 6 l stainless steel pressure apparatus fitted with a stirrer and metering devices, 890 g of deionized water, 74.1 g of a 33 wt % aqueous polystyrene seed dispersion (average particle diameter 32 nm) and 145.7 g of a 7 wt % aqueous itaconic acid solution were initially charged at room temperature and under nitrogen and heated to 90 C. under agitation. On reaching the aforementioned temperature 58.3 g of a 7 wt % aqueous sodium persulfate solution were added all at once. This was followed by the metered additions, commenced at the same time, of feed 1 and feed 2, mixed via an inline mixer and added in the form of an aqueous emulsion over a period of 3.5 hours, and feed 3 in the form of an aqueous solution, added over a period of 4 hours, in a continuous manner at constant flow rates while maintaining the aforementioned temperature.

(25) TABLE-US-00002 Feed 1: 1334 g of styrene 4.1 g of tert-dodecyl mercaptan 110 g of a 35 wt % aqueous solution of N-methylolacrylamide 45.3 g of a 45 wt % aqueous solution of an alkylarylsulfonic acid mixture (Dowfax 2A1) 570 g of deionized water Feed 2: 634 g of 1,4-butadiene Feed 3: 133 g of deionized water 10.0 g of sodium persulfate

(26) The polymerization mixture was subsequently allowed to undergo secondary polymerization at 90 C. for 30 minutes and cooled down to room temperature and performed a pressure equalization to the ambient pressure (1 atm absolute). A pH value of 7.5 was set by addition of 25 wt % aqueous sodium hydroxide solution. The aqueous polymer dispersion obtained had a solids content of 49.8 wt % based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 125 nm.

(27) Inventive Polymer Dispersion K3

(28) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 368 g instead of 142 g of n-butyl acrylate, 380 g instead of 622 g of styrene and 16.0 g of acrylonitrile.

(29) The aqueous polymer dispersion obtained had a solids content of 48.9% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 155 nm.

(30) Inventive Polymer Dispersion K4

(31) The preparation of comparative polymer dispersion V1 was repeated except that feed 1 used 384 g instead of 142 g of n-butyl acrylate, 396 g instead of 622 g of styrene and 222 g instead of 192 g of deionized water, but omitting the use of 45.7 g of a 35 wt % aqueous solution of N-methylolacrylamide.

(32) The aqueous polymer dispersion obtained had a solids content of 50.3% by weight based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 149 nm.

(33) Inventive Polymer Dispersion K5

(34) In a 2 l glass flask fitted with a stirrer and 4 metering devices, 464 g of deionized water, 29.6 g of a 33 wt % aqueous polystyrene seed dispersion (average particle diameter 32 nm) and 393 g of a 50 wt % aqueous maltodextrin solution (Roclys C1967S; weight average molecular weight of 26 700 g/mol and also a DE value of 19) were initially charged at room temperature and under nitrogen and heated to 90 C. under agitation. This was followed by the metered addition, commenced at the same time, of feed 1 over a period of 3.5 hours and feed 2 in the form of an aqueous solution over a period of 4 hours, in a continuous manner at constant flow rates while maintaining the aforementioned temperature.

(35) TABLE-US-00003 Feed 1: 9.7 g of acrylic acid 3.3 g of allyl methacrylate 319 g of styrene 306 g of n-butyl acrylate 37.2 g of a 35 wt % aqueous solution of N-methylolacrylamide Feed 2: 69.1 g of deionized water 5.2 g of sodium persulfate

(36) The polymerization mixture was subsequently allowed to undergo secondary polymerization at 90 C. for 30 minutes and cooled down to room temperature. A pH value of 7.0 was set by addition of 25 wt % aqueous sodium hydroxide solution. The aqueous polymer dispersion obtained had a solids content of 51.9 wt % based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 150 nm.

(37) Inventive Polymer Dispersion K6

(38) In a 2 l glass flask fitted with a stirrer and 4 metering devices, 462 g of deionized water, 29.6 g of a 33 wt % aqueous polystyrene seed dispersion (average particle diameter 32 nm) and 395 g of a 50 wt % aqueous maltodextrin solution (Roclys C1967S) were initially charged at room temperature and under nitrogen and heated to 90 C. under agitation. This was followed by the metered addition, commenced at the same time, of feed 1 over a period of 3.5 hours and feed 2 in the form of an aqueous solution over a period of 4 hours, in a continuous manner at constant flow rates while maintaining the aforementioned temperature.

(39) TABLE-US-00004 Feed 1: 9.7 g of acrylic acid 3.3 g of allyl methacrylate 195 g of styrene 442 g of n-butyl acrylate 24.1 g of deionized water Feed 2: 69.1 g of deionized water 5.2 g of sodium persulfate

(40) The polymerization mixture was subsequently allowed to undergo secondary polymerization at 90 C. for 30 minutes and cooled down to room temperature. A pH value of 7.0 was set by addition of 25 wt % aqueous sodium hydroxide solution. The aqueous polymer dispersion obtained had a solids content of 52.9 wt % based on the total weight of the aqueous dispersion. The number average particle diameter was determined as 149 nm.

(41) II Performance Testing

(42) Production of Impregnating Liquors

(43) Impregnating liquors were produced using Emsol K55 hydroxypropylated potato starch from Emsland Strke GmbH as a 20 wt % aqueous solution.

(44) The impregnating liquors were produced by the aqueous polymer dispersions K1 to K4 and also the comparative polymer dispersions V1 to V5 being homogeneously mixed with the aqueous solution of Emsol K55 hydroxylated potato starch such that the weight ratio of the particular solids contents of the aqueous polymer dispersions to the hydroxylated potato starch was 7:3 (corresponding to 42.9 parts by weight of starch per 100 parts by weight of solids of the aqueous polymer dispersions). The homogeneous polymer/starch mixtures thus obtained were subsequently adjusted to a solids content of 15% by weight by diluting with deionized water. The corresponding aqueous dispersions obtained are signified as impregnating liquors FK1 to FK4 and also FV1 to FV5. In addition, aqueous polymer dispersions K1, K4, K5 and K6 without added potato starch were adjusted to a solids content of 15 wt % solely by addition of deionized water. The corresponding aqueous dispersions obtained from the aqueous polymer dispersions K1 and K4 are signified as impregnating liquors FV6 and FV7, while the aqueous dispersions obtained from the aqueous polymer dispersions K5 and K6 are signified as impregnating liquors FK5 and FK6.

(45) Production of Bonded Fiber Webs

(46) Bonded fiber webs were produced using as raw web a needled polyethylene terephthalate spunbonded (40 cm length, 37 cm width) having a density of 125 g/m.sup.2 from Freudenberg-Politex.

(47) The bonded fiber webs were produced by saturating the raw web with the respective impregnating liquors FK1 to FK6 and also FV1 to FV7 in the longitudinal direction in an HVF impregnating rig with pad-mangle from Mathis (rubber roll Shore A=85/steel roll). In each case, the wet pick-up was adjusted to 162.5 g of impregnating liquor (corresponding to a solids content of 24.4 g). The impregnated fiber webs obtained were subsequently dried and cured in an LTV laboratory dryer with needle frame from Mathis (in circulating air operation). To this end, the impregnated fiber webs were each placed on an open needle frame, fixed by folding shut and then cured in the laboratory dryer at 200 C. for 3 minutes. The bonded fiber webs obtained in the process are signified as fiber webs FK1 to FK6 and also FV1 to FV7, depending on the impregnating liquors used.

(48) Determination of Breaking Strength in Transverse Direction

(49) Breaking strength in transverse direction was determined for fiber webs FK1 to FK6 and also FV1 to FV7 at room temperature in accordance with DIN 52123 using a breaking machine from Frank (model 71565). In each case, 5 separate measurements were carried out. The measurements in N/50 mm which are reported in table 1 represent the respective averages of these measurements. The higher the measurements obtained, the better the breaking strength in the transverse direction.

(50) Determination of Heat Resistance

(51) The heat resistance of fiber webs FK1 to FK6 and also FV1 to FV7 was determined by extension measurements using a breaking machine from Zwick (model Z10) with integrated heating chamber. To this end, 50210 mm strips (longitudinal direction) were die-cut out of fiber webs FK1 to FK6 and also FV1 to FV7 in the longitudinal direction and clamped with a length of 100 mm into the pulling device. After introduction to the heating chamber, the test strips were each heated at 180 C. for 60 minutes and thereafter extended at this temperature with increasing tensile force at an extension rate of 150 mm/min. The extension of the test strips in percent was determined on reaching a tensile force of 40 N/50 mm. The lower the extension obtained, the better the heat resistance. In each case, 5 separate measurements were carried out. The values likewise reported in table represent the averages of these measurements.

(52) TABLE-US-00005 TABLE 1 Results for breaking strength in transverse direction and heat resistance of fiber webs FK1 to FK6 and FV1 to FV7 Transverse breaking Extension at strength at room 40 N/50 mm temperature and 180 C. Fiber web [in N/50 mm] [in %] FK1 312 2.7 FK2 304 2.8 FK3 325 2.9 FK4 304 2.8 FK5 302 2.7 FK6 299 2.9 FV1 254 3.3 FV2 240 3.4 FV3 282 3.3 FV4 231 3.4 FV5 232 3.6 FV6 310 4.5 FV7 301 4.2

(53) It is clearly apparent from the results that the fiber webs produced with the inventive binder compositions have improved transverse breaking strength at room temperature and/or lower extension at 180 C.