EP3887464A1 - Crosslinkable polymer composition consisting of two copolymerisates, which are reactive with each other and have different glass transition temperatures - Google Patents

Abstract

The invention relates to a crosslinkable polymer composition in the form of an aqueous polymer dispersion or a polymer powder, containing A) a mixed polymerisate of one or more comonomers a1) from the group containing vinyl esters of unbranched or branched alkyl carboxylic acids with 1 to 18 C atoms, acrylic acid esters, and methacrylic acid esters of branched or unbranched alcohols with 1 to 15 C atoms, dienes, olefins, vinyl aromatics, and vinyl halides, and 0.1 to 30 wt.%, based on the total weight of the comonomers, of one or more ethylenically unsaturated functional comonomers a2, which contain carboxyl, hydroxy, or NH groups, and B) a mixed polymerisate of one or more comonomers b1) from the group containing vinyl ester or unbranched or branched alkyl carboxylic acids with 1 to 18 C atoms, acrylic acid esters, and methacrylic acid esters of branched or unbranched alcohols with 1 to 15 C atoms, dienes, olefins, vinyl aromatics, and vinyl halides, and 0.1 to 30 wt.%, based on the total weight of the comonomers, of one or more ethylenically unsaturated functional comonomers b2) which can react with the functional groups of the comonomers a2 ) and which contain epoxy, N-methylol, or isocyanate groups. The invention is characterized in that one of the mixed polymerisates A) or B) has a glass transition temperature Tg of less than 30 °C and the respective other mixed polymerisate A) or B) has a glass transition temperature Tg of more than 50 °C.

Description

NETWORKABLE POLYMER COMPOSITION OF TWO REACTIVE COPOYLMERISATS OF DIFFERENT GLASS TRANSITION TEMPERATURES

The invention relates to a crosslinkable polymer composition in the form of an aqueous polymer dispersion or a polymer powder, and to the use of the crosslinkable polymer composition for binding and coating particulate materials, in particular fibers. To avoid the emission of formaldehyde, which occurs, for example, when N-methylol-functional polymers are used as binders for fibers, the use of “formaldehyde-free” binders is known. These are generally crosslinkable polymer compositions which comprise a car - contain boxyl-functional polymer and a polymer with functional groups which crosslink with the carboxyl groups, for example epoxy groups.

EP 0 894 888 A1 describes a pulverulent, crosslinkable textile binder composition which contains a carboxyl-functional copolymer and a pulverulent compound having at least two epoxy or isocyanate groups. EP 1 136 516 B1 describes the use of a crosslinkable polymer composition for strengthening textile fabrics, the polymer composition comprising a carboxyl-functional copolymer and an epoxy-functional copolymer, the glass transition temperature Tg of which is in each case at least 45 ° C. EP 1 203 647 B1 describes a polymer mixture of an epoxy-functional styrene-butyl acrylate copolymer and a carboxyl-functional styrene-butyl acrylate copolymer, each of which has a Tg of greater than 50 ° C., for binding wood chips during production of wooden pressed panels. WO 2013/165979 A1 describes formaldehyde-free glass fiber binders based on an aqueous binder composition with a first water-soluble and carboxyl-functional copolymer with a Tg of at least 30 ° C. and a second water-insoluble copolymer with a Tg of at least 10 ° C., the second copolymer containing functional groups which crosslink with the carboxyl groups of the first copolymer. WO 2016/087255 A1 describes an aqueous polymer dispersion which contains first polymer particles with carboxyl groups and a particle size of 80 to 1000 nm and additionally contains second polymer particles with epoxy groups and a particle size of 5 to 70 nm.

If crosslinkable polymer compositions with a relatively low glass transition temperature are used, products with insufficient initial strength are obtained after crosslinking at a relatively high temperature, which can only be stacked after cooling and which tend to stick when stored. When using such crosslinkable polymer compositions, however, block-stable molded parts which do not stick together should be obtained after crosslinking at a relatively high temperature. Therefore, relatively hard copolymers with a relatively high glass transition temperature and with a high melt viscosity are also used in the prior art. At room temperature, however, this leads to incomplete filming and thus to an uneven distribution of the binder on the substrate to be treated.

The invention relates to a crosslinkable polymer composition in the form of an aqueous polymer dispersion or a polymer powder containing

A) a copolymer of one or more comonomers a1) from the group comprising vinyl esters of unbranched or branched alkylcarboxylic acids with 1 to 18 C atoms, acrylic acid esters and methacrylic acid esters of branched or unbranched alcohols with 1 to 15 C atoms, dienes , Olefins, vinyl aromatics and vinyl halides, and 0.1 to 30% by weight, based on the total weight of the comonomers, one or more ethylenically unsaturated, functional comonomers a2) which contain carboxyl, hydroxyl or NH groups, and

B) a copolymer of one or more comonomers b1) from the group containing vinyl esters of unbranched or branched alkylcarboxylic acids with 1 to 18 C atoms, acrylic acid esters and methacrylic acid esters of branched or unbranched alcohols with 1 to 15 C atoms, dienes , Olefins, vinyl aromatics and vinyl halides, and 0.1 to 30% by weight, based on the total weight of the comonomers, of one or more ethylenically unsaturated, functional comonomers b2) which react with the functional groups of the comonomers a2) can, and which contain epoxy, N-methylol or isocyanate groups, characterized in that one of the copolymers A) or B) has a glass transition temperature Tg of less than 30 ° C and the other copolymer A) or B) has a glass transition temperature Tg greater than 50 ° C.

Vinyl esters suitable for the copolymers A) and B) are vinyl esters of unbranched or branched carboxylic acids having 1 to 18 carbon atoms. Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methyl vinyl acetate, vinyl pivalate and vinyl esters of 1 -branched monocarboxylic acids with 9 to 11 carbon atoms, for example VeoVa9 ^R or VeoVal0 ^R (trade names of Momentive company). Vinyl acetate is particularly preferred.

Monomers from the group of the esters of acrylic acid and the esters of methacrylic acid which are suitable for the copolymers A) and B) are esters of unbranched or branched alcohols having 1 to 15 carbon atoms. Preferred methacrylic acid esters or acrylic acid esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 2-ethylhexyl acrylate, norbate. Especially methyl acrylate, methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate and norbornyl acrylate are preferred.

Dienes suitable for the copolymers A) and B) are 1,3-butadiene and isoprene. Examples of copolymerizable olefins are ethene and propene. Styrene and vinyl toluene can be copolymerized as vinyl aromatics. Vinyl chloride from the group of vinyl halides is usually used.

Suitable carboxyl-functional comonomers a2) are ethylenically unsaturated mono- and dicarboxylic acids and the half esters of dicarboxylic acids. Examples of carboxyl-functional comonomers a2) are acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid and itaconic acid, the half esters of maleic and fumaric acid, monovinyl succinic acid esters, methylene malonic acid. Suitable hydroxy-functional comonomers a2) are hydroxyalkyl acrylates and hydroxyalkyl methacrylates with C 1 -C 8 -alkyl radical, preferably hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, hydroxybutyl acrylate and methacrylate. Suitable NH-functional comonomers a2) are

(Meth) acrylamide, diacetone acrylamide, maleimide, maleic and fumaric acid monoalkyl ester amide, maleic and fumaric acid diamide, glutaric and succinic acid monovinyl ester amide, glutaric and amber acid monoallylesteramide. The carboxyl-functional comonomers a2) are preferred. The proportion of the functional comonomers a2) in the copolymer A) is 0.1 to 30% by weight, preferably 0.1 to 25% by weight, particularly preferably 2 to 25% by weight, in each case based on the total weight of the comonomers al) and a2).

Suitable epoxy-functional comonomers b2) are, for example, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, vinyl glycidyl ether, vinylcyclohexene oxide. Suitable N-methylol-functional comonomers b2) are N-methylolacrylamide (NMA), N-methylolmethacrylamide, N-methylolallyl carbamate. Suitable isocyanate Functional comonomers b2) are 2-methyl-2-isocyanatopropyl methacrylate and isopropenyl-dimethylbenzyl isocyanate (TMI). The epoxy-functional comonomers b2) are preferred. The proportion of the functional comonomers b2) in the copolymer B) is 0.1 to 30% by weight, preferably 2 to 30% by weight, in each case based on the total weight of the comonomers b1) and b2).

Preferred copolymers A) and B) are those

of vinyl acetate; of vinyl acetate and ethylene; of vinyl acetate and vinyl chloride; of vinyl acetate and ethylene and vinyl chloride; of vinyl acetate and one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl -2-ethylhexanoic acid ester, vinyl ester of an alpha-branched carboxylic acid, in particular versatic acid vinyl ester (VeoVa9 ^R , VeoVal0 ^R ), and optionally ethylene;

of vinyl acetate and butyl acrylate and / or 2-ethylhexyl acrylate, and optionally ethylene;

of n-butyl acrylate and / or 2-ethylhexyl acrylate;

of methyl methacrylate with butyl acrylate and / or 2-ethylhexyl acrylate, and / or 1, 3-butadiene;

of styrene and 1, 3-butadiene; of styrene and butyl acrylate; of styrene and methyl methacrylate and butyl acrylate; where n-, iso-, tert-butyl acrylate can be used as butyl acrylate. These copolymers A and B, which are mentioned as preferred, each contain the comonomer units just mentioned and contain functional groups in the amounts just described. The data in% by weight add up to 100% by weight.

The selection of monomers or the selection of the proportions by weight of the comonomers al) or bl) is carried out in such a way that the aforementioned glass transition temperatures Tg result for the copolymers A) or B). One of the copolymers A) or B) preferably has a glass transition temperature Tg of less than 20 ° C. and the other copolymer A) or B) has a glass transition temperature Tg of more than 70 ° C. The Tg can be roughly predicted using the Fox equation. According to Fox TG, Bull. Am. Physics Soc. 1, 3, page 123 (1956) applies: 1 / Tg = xl / Tgl + x2 / Tg2 + ... + xn / Tgn, where xn stands for the mass fraction (% by weight / 100) of the monomer n, and Tgn is the glass transition temperature in Kelvin of the homopolymer of monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975). The glass transition temperature Tg of the copolymers A) or B) can be determined in a known manner by means of DSC (dynamic differential thermal analysis, DIN EN ISO 11357-1 / 2), for example using the dynamic differential calorimeter DSC1 from Mettler-Toledo in an open crucible can be determined at a heating rate of 10 K / min. In the heat flow diagram, the temperature at the center of the step (center point = half the step height of the heat flow step) of the second heating curve is evaluated as the glass transition temperature.

In a further preferred embodiment, the copolymer with a glass transition temperature Tg of less than 30 ° C. also has a minimum film-forming temperature MFT of less than 30 ° C., and that copolymer with a glass transition temperature Tg of greater than 50 ° C. also has a minimum film-forming temperature MFT of greater than 50 ° C. The minimum film forming temperature MFT is defined as the temperature below which a polymer no longer forms a closed polymer film. The minimum film formation temperature (MFT) is determined in accordance with DIN ISO 2115 using the MFT II 50-030 from Coesfeld. The MFT-Bank has a calibrated temperature gradient from 0 ⁰ C to 20 ° C. The measurement samples can be produced by drawing the aqueous dispersion of the polymer onto an aluminum foil in the form of a film using a 200 μm doctor blade, which is applied directly to the MFT bench. The dispersion film is dried for 90 minutes, with a weak dry air flow is continuously passed over the sample.

The copolymers A) or B) are prepared in a manner known to the person skilled in the art, preferably by the emulsion polymerization process. The radical-initiated emulsion polymerization of ethylenically unsaturated monomers in an aqueous medium is described, for example, in Encyclopedia of Polymer Science and Engineering, Vol. 8, pages 659-677, John Wiley & Sons Inc. , 1987 and described in EP 1 916 275 A1.

The polymerization temperature is generally, but not necessarily, less than 100 ° C. The copolymerization of gaseous comonomers such as ethylene can also be carried out under pressure, generally between 5 bar and 100 bar. The polymerization is initiated using the initiators or redox initiator combinations customary for emulsion polymerization. Anionic and nonionic emulsifiers and protective colloids can be used for stabilization. The aqueous dispersions obtainable thereby preferably have a solids content of 40 to 70% by weight.

The crosslinkable polymer composition in the form of an aqueous polymer dispersion can be prepared by mixing the aqueous dispersion of copolymer A) and the aqueous dispersion of copolymer B). To produce the crosslinkable polymer composition in the form of a polymer powder, the mixture of the aqueous dispersions of copolymer A) and polymer B) is preferably dried in a known manner, if appropriate after adding protective colloids as a spraying aid, for example by spray drying. The aqueous dispersions of interpolymer A) and interpolymer B) can also be dried separately and then mixed as a powder. The copolymers A) and B) are preferably present in a ratio such that the molar ratio of functional comonomer units a2) to b2) varies from 5: 1 to 1: 5, preferably 2: 1 to 1: 2. The copolymers A) and B) are particularly preferably present in such a ratio that the ratio of functional comonomer units a2) to b2) is equimolar.

The crosslinkable polymer composition is suitable for binding particulate materials. In particular for the production of moldings from particulate materials such as fiber materials or particulate materials from mineral materials, plastics or natural materials such as wood chips, cork particles, glass particles or glass powder, in particular recycled glass and hollow glass spheres, or from combinations of these materials.

The preferred application is as a binder for fiber materials. Natural or synthetic raw materials are suitable as fiber material. Examples of these are synthetic fibers based on fiber-forming polymers such as viscose, polyester and polyester chaff fibers, polyamide, polypropylene, polyethylene fibers. Mineral fibers, such as glass fibers, ceramic fibers, carbon fibers, are also suitable. Examples of natural fiber materials are wood, cellulose, wool, cotton, jute, flax, hemp, coconut, ramie and sisal fibers. The fibers can also be used in the form of woven textiles, yarns or in the form of nonwovens such as scrims or knitted fabrics. These nonwovens can optionally be mechanically pre-consolidated, for example needled.

Depending on the application, the molded articles are produced at elevated temperature, if appropriate under increased pressure. The temperature for the solidification of the shaped bodies is preferably 90 ° C to 220 ° C. If the molded articles are produced under pressure, pressures of 1 to 200 bar are preferred. The crosslinkable polymer composition is generally used in an amount of 5 to 50% by weight, based on the material to be bound. The amount of binder depends on the substrate to be bound and is preferably between 10 and 40% by weight in the case of polyester fibers, cotton fibers, and preferably in the range of 20 in the case of natural fibers such as hemp, flax, sisal, jute up to 40% by weight. In the case of glass and mineral fibers and other mineral materials such as glass balls, the preferred range is between 10 and 30% by weight.

In the manufacture of fiber molded articles, the procedure is such that the crosslinkable polymer composition is sprayed on or mixed with the fibers, this fiber / polymer mixture is designed according to the customary methods of nonwoven technology, if appropriate after carding the fiber / polymer mixture and needles , and is bound by increasing the temperature, if appropriate using pressure and / or superheated steam.

The fiber binding can also be carried out by sprinkling a powdery polymer composition into a fabric, scrim or in a previously laid fiber bed (if necessary after carding the fiber / powder mixture and needles), and the polymer powder by increasing the temperature, optionally with the additional use of Pressure and or hot steam, melted and hardened.

The polymer composition is also suitable for laminating or laminating two or more fabrics, scrims or nonwovens to one another, the polymer composition serving as a binder between the two substrates to be bonded to one another. For this purpose, the polymer preparation is introduced between the layers and the laminate is bound by increasing the temperature, optionally with the additional use of pressure and or superheated steam. The polymer composition can also be used for coating fibers, in particular for coating glass fibers. Another use is as a binder for adhesive raw materials.

Another application is the production of wood panels (HDF and MDF) and wood extrudates, the crosslinkable polymer composition being mixed with the wood particles and then being extruded.

The following examples serve to explain the invention further:

Example 1: Preparation of a carboxyl-functional styrene-acrylate dispersion

425 g of deionized water, 2.0 g of sodium lauryl sulfate, 2 g of ethylene oxide / propylene oxide block copolymer (Genapol PF 20 from Clariant AG) and 13.0 g of potassium peroxodisulfate were placed in a reactor with a volume of 3 liters and placed under nitrogen at room temperature Stirred for 30 minutes. Then 129.0 g of the pre-emulsion were metered into the reactor and heated to 80 ° C.

At 80 ⁰ C this template was polymerized for 30 minutes. The initiator solution (6.0 g of potassium peroxodisulfate and 144 g of water) was then metered in over the course of 4.5 hours, and the rest of the pre-emulsion was metered into the reactor over the course of 4 hours. Pre-emulsion:

213.6 g butyl acrylate

763.6 g styrene

74.8 g methacrylic acid

10.7 g of hydroxyethyl acrylate

10.7 g of 2-acrylamido-2-methylpropanesulfonic acid (50%)

13.9 g dodecyl mercaptan After the metered additions, the polymerization was continued for 2 hours at 85 ° C. and the pH was adjusted to 8 using ammonia. The solids content of the dispersion was 55% by weight and the viscosity was 100 mPa. s and the Tg at 70 ° C.

Example 2: Preparation of a carboxyl-functional styrene-acrylate dispersion

Like example 1, but the amount of styrene was reduced to 549.7 g and the amount of butyl acrylate was increased to 427.5 g. The solids content of the dispersion was 55% by weight and the viscosity was 130 mPa. s and the Tg at 30 ° C.

Example 3: Preparation of an epoxy-functional styrene-acrylate dispersion

4303 g of deionized water, 8.6 g of sodium lauryl sulfate and 13.0 g of sodium bicarbonate and 8.6 g of potassium peroxodisulfate were placed in a reactor with a volume of 3 liters and stirred under nitrogen at room temperature for 30 minutes.

Then 93.0 g of pre-emulsion were metered into the reactor and heated to 80.degree. The template was polymerized at 80 ° C. for 30 minutes. The initiator solution (5.5 g of potassium peroxodisulfate and 151 g of water) was then metered into the reactor over the course of 4.5 hours and the rest of the pre-emulsion within 4 hours.

Pre-emulsion:

165.4 g butyl acrylate

722.0 g styrene

198.0 g glydidyl methacrylar

5.5 g of hydroxyethyl acrylate

22.0 g of 2-acrylamido-2-methylpropanesulfonic acid (50%)

14.3 g dodecyl mercaptan

2.8 g Na bicarbonate After the metered additions, the polymerization was continued for 2 hours at 85 ° C. and the pH was adjusted to 8 using ammonia. The solids content of the dispersion was 55% by weight and the viscosity was 300 mPa. s and the Tg at 60 ° C.

Example 4: Preparation of an epoxy-functional styrene-acrylate dispersion

As in Example 3, but the amount of styrene was reduced to 425.4 g and the amount of butyl acrylate was increased to 462.0 g. The

The solids content of the dispersion was 55% by weight and the viscosity was 150 mPa. s and the Tg at 30 ° C.

Preparation of the dispersion mixtures:

The dispersions were mixed in the proportions given in Table 1 to obtain equimolar molar ratios with respect to the carboxyl and epoxy group (156 g carboxyl-functional dispersion and 100 g epoxy-functional dispersion).

Table 1:

MAS = methacrylic acid, GMA = glydidyl methacrylar

Determination of blocking resistance: To test the blocking resistance of the dispersion mixtures, test cards from BYK-Gardner were coated with the dispersion mixtures, each with a thickness of 50 pm wet layer. After drying at room temperature for 6 hours, the coating of the cards was crosslinked at 150 ° C. for 5 minutes. Two coated cards were placed with their coated side on top of one another and subjected to 3.1 -IO ⁴ N / m ^{2 for} 2 h at 60 ° C.

The force that was required to separate the cards from one another was then determined at room temperature.

The assessment was made using the following scheme. The results are summarized in Table 2.

Grade 0 0 N / m ²

Grade 1 0.10 0.8.10 ⁴ N / m ²

Grade 2 0.81 - 1.6 · 10 ⁴ N / m ²

Grade 3 1.61 - 2, 4 · 10 ⁴ N / m ² ,

Note 4 2.41 to 3, 2 x 10 ⁴ N / m ^2,

Note 5> 3, 2 · 10 ⁴ N / m ² .

Table 2:

MAS = 70 mmol / 156 g dispersion, GMA = 70 mmol / 100 g dispersion When mixing V-Ex. 7 there was no film formation at room temperature and therefore no block stability could be determined. In contrast, the mixture V-Ex. 8 obtained a homogeneous film at room temperature. The blocking resistance at 60 ° C was very low (grade 5).

With the mixtures of Examples 5 and 6, uniform films with good blocking stability at 60 ° C. were obtained at room temperature.

Claims

Claims: 1. Crosslinkable polymer composition in the form of an aqueous polymer dispersion or a polymer powder, containing A) a copolymer of one or more comonomers al) from the group containing vinyl esters of unbranched or branched alkylcarboxylic acids with 1 to 18 carbon atoms, acrylic acid esters and methacrylic acid esters of branched or unbranched alcohols with 1 to 15 carbon atoms - Men, dienes, olefins, vinyl aromatics and vinyl halides, and 0.1 to 30 wt .-%, based on the total weight of the comonomers, one or more ethylenically unsaturated, functional comonomers a2), which carboxyl, hydroxy or NH Groups included, and B) a copolymer of one or more comonomers b1) from the group comprising vinyl esters of unbranched or branched alkylcarboxylic acids having 1 to 18 carbon atoms, acrylic acid esters and methacrylic acid esters of branched or unbranched alcohols having 1 to 15 carbon atoms - Men, dienes, olefins, vinyl aromatics and vinyl halides, and 0.1 to 30 wt .-%, based on the total weight of the comonomers, one or more ethylenically unsaturated, functional comonomers b2) which react with the functional groups of the comonomers a2) can, and which contain epoxy, N-methylol or isocyanate groups, characterized in that one of the copolymers A) or B) has a glass transition temperature Tg of less 30 ° C and the other copolymer A) or B) has a glass transition temperature Tg greater than 50 ° C. 2. Crosslinkable polymer composition according to claim 1, characterized in that the copolymer with a glass transition temperature Tg of less than 30 ° C has a minimum film-forming temperature MFT of less than 30 ° C, and that copolymer with a glass transition temperature Tg of greater than 50 ° C has a minimum film-forming temperature MFT of greater than 50 ° C. 3. Crosslinkable polymer composition according to claim 1, characterized in that one of the copolymers A) or B) a glass transition temperature Tg of less 20 ° C and the other copolymer A) or B) has a glass transition temperature Tg greater than 70 ° C. 4. Crosslinkable polymer composition according to claim 1 to 3, characterized in that the copolymers A) and B) are each copolymers of methyl methacrylate with butyl acrylate and / or 2-ethylhexyl acrylate, and / or 1, 3-butadiene, of styrene and 1,3-butadiene, of styrene and butyl acrylate, of styrene and methyl methacrylate and butyl acrylate, it being possible to use n-, iso-, tert-butyl acrylate as butyl acrylate. 5. Crosslinkable polymer composition according to claim 1 to 4, characterized in that carboxyl-functional comonomers a2) from the group of ethylenically unsaturated mono- and dicarboxylic acids and the half esters of dicarboxylic acids are copolymerized. 6. Crosslinkable polymer composition according to claim 5, characterized in that epoxy-functional comonomers b2) from the group glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, vinyl glycidyl ether or vinylcyclohexene oxide are copolymerized. 7. Use of the crosslinkable polymer composition after Claims 1 to 6 for binding particulate materials. 8. Use of the crosslinkable polymer composition according to claim 1 to 6 for the production of moldings from particulate materials. 9. Use of the crosslinkable polymer composition according to claim 1 to 6 as a binder for fiber materials. 10. Use of the crosslinkable polymer composition according to claim 1 to 6 for coating fibers. 11. Use of the crosslinkable polymer composition according to Claims 1 to 6 as binders for adhesive raw materials. 12. Use of the crosslinkable polymer composition according to Claims 1 to 6 for the production of wooden panels and wooden extrudates.