METHOD FOR PRODUCING A THERMALLY DEFORMABLE POLYMER / FIBER COMPOSITE

Description

[0001] The invention relates to a method for producing a thermoformable polymer / fiber composite using a polymer P polymerized in the presence of an acrylic acid copolymer. The invention also relates to the composites obtainable according to the inventive method, their various uses, a method for producing polymer / fiber molded parts by thermoforming the polymer / fiber composite, and the polymer / fiber molded parts themselves.

[0002] The production of wood fiberboard essentially begins with wood chips, which are pre-treated hydrothermally using steam, then treated under pressure and temperatures above 140°C, and finally further refined under pressure in so-called refiners. The resulting aqueous wood fiber slurry is then transferred to the blowline, a pipe with significantly lower pressure. This causes the water to evaporate, thus serving as a gaseous transport medium for the wood fibers through the blowline (hydropneumatic conveying). The wood fibers are then dried by additionally blowing heated, dry air into the blowline and are pneumatically transported further.To ensure the most uniform application of the aqueous binder required for the production of wood fiberboards onto the fibers, the binder is sprayed into the blowline at one or more points before the heated, dry air is blown in. The binder-coated fibers that accumulate after drying are separated and transferred into a fiber mat. This fiber mat is then compressed, if necessary, by means of a "cold" pre-compression and subsequently pressed under pressure and high temperature (150 to 230 °C) to form a board-shaped wood-based material with a density of 250 to 1000 kg / m³ (a "hot" compression).Under the compression temperatures, a thermosetting binder forms from binders such as formaldehyde resins (e.g., urea / formaldehyde, phenol-formaldehyde, melamine-formaldehyde, melamine / urea / formaldehyde, or melamine / phenol / formaldehyde resins) or isocyanates (e.g., methylene diisocyanate or toluene diisocyanate). Due to the use of thermally curable binders, the resulting wood fiberboards are thermosetting after "warm" compression, meaning they can no longer be thermoformed.

[0003] WO 01 / 27163 teaches thermally curable polymer dispersions and their use in the production of thermosetting polymer / fiber composites. One application is the production of wood fiberboards whose fibers are bonded using the blow-line process. The styrene acrylates used according to WO 01 / 27163 are produced in the presence of carboxyl-group-bearing polymers whose building blocks are maleic anhydride, acrylic acid, and acrylic acid / maleic acid esters with an ethoxylated oleylamine. This carboxyl-group-bearing polymer is a comb polymer produced analogously to a polymer with hydrophobic residues that are also thermally crosslinkable due to the amino group. The product is therefore also a thermoset, meaning it is no longer deformable after thermal curing.

[0004] WO 2017 / 140520 describes the process of bonding wood fibers in the blowline with a thermally non-crosslinking polymer dispersion and subsequently pressing them into fiberboards that remain formable despite compression at high temperatures. The binders used are styrene / methacrylate polymers obtained by polymerization in the presence of a polymer composed of 95 parts by weight of acrylic acid. The styrene / methacrylate polymer contains 5% by weight of other monomers incorporated into the polymer. The resulting molded parts are thermally formable and yet possess good service strength. However, it is desirable to further improve their water resistance so that the molded parts can also be used, for example, in damp environments or in outdoor applications.

[0005] The present invention was therefore based on the objective of finding a polymer / fiber composite which can be thermally deformed into shaped bodies that exhibit both good mechanical strength and dimensional stability in humid climates.

[0006] The object is achieved according to the invention by a method for producing a thermoformable polymer / fiber composite using a polymer P and a fibrous substrate, wherein the latter are particles with a ratio of their longest dimension to their shortest dimension of at least 3, i.e. ≥ 3, preferably ≥ 5, wherein The fibrous substrate is introduced into a gas stream, then the fibrous substrate in the gas stream is brought into contact with an aqueous dispersion of a polymer P with a glass transition temperature Tg ≥ 35 and ≤ 150 °C measured according to DIN EN ISO 11357-2 (2013-09), then the fibrous substrate in contact with the aqueous dispersion of polymer P is dried in the gas stream and subsequently deposited, then the resulting deposited fibrous substrate is converted into a fiber mat, and then the resulting fiber mat is compacted at a temperature ≥ the glass transition temperature Tg of the polymer P to form the polymer / fiber composite, whereby the density of the polymer / fiber composite increases by a factor of ≥ 3 compared to the corresponding fiber mat. characterized in that the aqueous dispersion of polymer P is obtained by radically initiated emulsion polymerization of a monomer composition consisting of 5 to 30 wt.%, one or more monomers M1, selected from esters of acrylic and / or methacrylic acid having 2 to 8 carbon atoms, alkanols 70 to 95 wt.% Styrene and / or methyl methacrylate (monomers M2), and 0 to 10 wt.% at least one further ethylene-unsaturated compound (monomer M3) which can be copolymerized with monomers M1 and M2, each in relation to the total amount of monomers M, in an aqueous medium in the presence of a polymer A or a polymer mixture A, wherein the polymer A and the polymer mixture A are each composed of 40 to 70 wt.% Acrylic acid (monomer A1), 30 to 60 wt.% Maleic acid and / or maleic anhydride (monomer A2), 0 to 5 wt.% at least one further ethylene-unsaturated compound which can be copolymerized with the monomers A1 and A2 (monomer A3), and wherein the total amounts of monomers A add up to 100 wt.%, provided that neither polymer A nor polymer mixture A is composed of an ester selected from among the esters of ethylene unsaturated monocarboxylic acids with amines having at least two hydroxyl groups, the semiesters and the diesters of ethylene unsaturated dicarboxylic acids with amines having at least two hydroxyl groups.

[0007] The present invention further relates to the polymer / fiber composites obtainable according to the inventive method.

[0008] Furthermore, the present invention relates to the use of the polymer / fiber composite for the production of a polymer / fiber molded part which differs in shape from the polymer / fiber composite used, and to the method for its production by heating the polymer / fiber composite to a temperature above the glass transition temperature Tg of polymer P, forming it into the desired shape of the polymer / fiber molded part at a temperature ≥ Tg, and then cooling the resulting polymer / fiber molded part to a temperature below the glass transition temperature Tg of polymer P while maintaining its shape. The present invention thus also relates to the polymer / fiber molded part obtainable according to this method and its use as a furniture component, wall decoration component, or interior component in automotive applications.

[0009] Furthermore, the present invention relates to the aqueous dispersion of polymer P used according to the invention and to a method for its production.

[0010] A characteristic feature of the method according to the invention is that a fibrous substrate is introduced into a gas stream. According to the invention, all fibrous substrates can be used. A fibrous substrate is understood to be particles whose ratio of their longest dimension to their shortest dimension is at least 3, preferably ≥ 5, advantageously ≥ 10, and particularly advantageously ≥ 50, and whose shortest dimension is ≤ 2 mm, advantageously ≥ 0.001 and ≤ 0.5 mm, and particularly advantageously ≥ 0.001 and ≤ 0.1 mm. The shortest dimension is determined at an angle of 90° to the line connecting its longest dimension.

[0011] The fibrous substrates can be natural fibers, such as plant, animal and mineral fibers, or artificially produced chemical fibers made from natural or synthetic polymers.Examples of plant fibers include cotton fibers, flax fibers, hemp fibers, kenaf fibers, jute fibers, wood fibers, and sisal fibers. Examples of animal fibers include wool and other animal hair. An example of mineral fibers is rock wool. An example of man-made fibers of natural origin is viscose fibers. Examples of man-made fibers based on synthetic polymers include polyester fibers, such as polytrimethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, and polybutylene terephthalate fibers, as well as the various polycarbonate fibers, polyolefin fibers, such as polyethylene and polypropylene fibers, polyamide fibers, such as polycaprolactam fibers (polyamide 6), polyamide fibers made of hexamethylenediamine and adipic acid (polyamide 6.6), polyamide fibers made of hexamethylenediamine and terephthalic acid (polyamide 6T), polyamide fibers made of para-phenylenediamine and terephthalic acid (aramid), and mineral fibers. Glass fibers, carbon fibers or basalt fibers.However, according to the invention, it is advantageous to use natural fibers, in particular of plant origin and especially wood fibers, such as those obtained in particular from a refiner.

[0012] In the context of the present invention, a gas flow is understood to be the directed transport of a gaseous substance along a pressure gradient, for example in a container or a pipe. In principle, any substance that is gaseous under the transport conditions (especially pressure and temperature) can be used. For example, organic and / or inorganic solvent vapors, such as water vapor or nitrogen-containing gas mixtures, such as air, are used. According to the invention, water vapor / air mixtures in a wide mixing ratio are advantageously used.

[0013] According to the invention, the fibrous substrate is brought into contact with the aqueous dispersion of polymer P in the gas stream. If this contacting takes place in a blow line, advantageously via one or more injection nozzles, care must be taken to ensure that the contacting in the blow line occurs at one or more points in the direction of flow before the heated dry air is blown in to dry the wood fibers.

[0014] Subsequently, the fibrous substrate, which has been brought into contact with the aqueous dispersion of polymer P, is dried in a gas stream and then separated. The drying of the resulting fibrous substrate is achieved, for example, by separating and condensing the water vapor or in a blowline by introducing sufficient heated, dry air to reduce the relative humidity in the resulting gas mixture to ≤ 10% or even ≤ 5%. This measure dries the mixture of fibrous substrate and polymer P. For the purposes of this document, drying is defined as reducing the residual moisture content of the substrate / polymer mixture to ≤ 15% by weight and advantageously to ≤ 10% by weight.In this document, residual moisture content is defined as the percentage weight difference, based on the substrate / polymer mixture used, that results from drying 1 g of substrate / polymer mixture in a drying oven for one hour at 120 °C. The substrate / polymer mixture is separated using standard methods for separating solids from gas mixtures, such as by sieving or by utilizing centrifugal forces via cyclone separators.

[0015] Subsequently, the resulting deposited substrate / polymer mixture is converted into a fibrous mat according to the invention, for example by appropriately sprinkling the deposited substrate / polymer mixture onto a surface or, in continuous operation, onto a conveyor belt. This fibrous mat can, optionally after mechanical pre-compaction at a temperature significantly, generally at least 10 Kelvin, below the glass transition temperature Tg of the polymer P, have a thickness of ≥ 1 and ≤ 50 cm, advantageously ≥ 1 and ≤ 30 cm, and particularly advantageously ≥ 1 and ≤ 15 cm, and a density of ≥ 20 and ≤ 700 g / l, often ≥ 50 and ≤ 500 g / l, and frequently ≥ 100 and ≤ 350 g / l.

[0016] Subsequently, the fiber mat thus obtained is compacted at a temperature ≥ the glass transition temperature Tg of the polymer P to form a polymer / fiber composite. Compaction is defined as pressing the fiber mat under pressure at this temperature to form a polymer / fiber composite. The density of the polymer / fiber composite increases compared to the corresponding fiber mat, depending on the fibrous substrate used, by a factor of ≥ 3 and advantageously by a factor of ≥ 6. The thickness of the polymer / fiber composite also decreases accordingly compared to the corresponding fiber mat. It is important to note that the polymer / fiber composite according to the invention advantageously has a planar, flat shape. Of course, depending on the chosen mold, the polymer / fiber composite according to the invention can also have any non-planar, three-dimensional shape.

[0017] A key aspect of the process is the use of the aqueous dispersion of polymer P according to the invention. The present invention therefore also relates to an aqueous dispersion of polymer P obtainable by radical-initiated emulsion polymerization of a monomer composition consisting of 5 to 30 wt.%, one or more monomers M1, selected from esters of acrylic and / or methacrylic acid having 2 to 8 carbon atoms, alkanols 70 to 95 wt.% Styrene and / or methyl methacrylate (M2), and 0 to 10 wt.% at least one further ethylene unsaturated compound (M3) which can be copolymerized with the monomers M1 and M2, each in relation to the total amount of monomers M in an aqueous medium in the presence of a polymer A or a polymer mixture A, wherein the polymer A and the polymer mixture A are each composed of 40 to 70 wt.% Acrylic acid (monomer A1), 30 to 60 wt.% Maleic acid and / or maleic anhydride (monomer A2), 0 to 5 wt.% at least one further ethylene-unsaturated compound which can be copolymerized with the monomers A1 and A2 (monomer A3), and wherein the total amounts of monomers A add up to 100 wt.%, provided that neither polymer A nor polymer mixture A is composed of an ester selected from among the esters of ethylene unsaturated monocarboxylic acids with amines having at least two hydroxyl groups, the semiesters and the diesters of ethylene unsaturated dicarboxylic acids with amines having at least two hydroxyl groups.

[0018] The essential aspect of the process is that the aqueous dispersion of polymer P is produced by radically initiated emulsion polymerization of a composition of ethylene-unsaturated monomers M (monomers M) in an aqueous medium in the presence of a polymer A or a polymer mixture A, wherein the polymer A and the polymer mixture A are each composed of 40 to 70 wt.% Acrylic acid (monomer A1), 30 to 60 wt.% Maleic acid and / or maleic anhydride (monomer A2), 0 to 5 wt.% at least one further ethylene-unsaturated compound which can be copolymerized with the monomers A1 and A2 (monomer A3), and wherein the total amounts of monomers A add up to 100 wt.%.

[0019] Whenever this application refers to monomers with carboxylic acid residues, this always includes their water-soluble salts, for example the sodium, potassium or ammonium salts.

[0020] A polymer mixture A is understood to consist of two or more polymers composed of the monomers A1, A2, and A3, the total amount of which contains the ratio according to the invention. It is therefore possible, for example, for the acrylic acid content of one polymer to be greater than 70 wt.%, as long as the acrylic acid content of the other polymer is smaller and the total proportions are satisfied.

[0021] For the production of the polymer A used according to the invention, as well as the polymer mixture A, at least one monomer A3, in particular an ethylene-unsaturated compound that can be readily copolymerized with monomers A1 and A2 by radical action, is suitable, such as ethylene, vinylaromatic monomers such as styrene, α-methylstyrene, o-chlorostyrene or vinyltoluenes, vinyl halides such as vinyl chloride or vinylidene chloride, esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of α,β-monoethylene-unsaturated mono- and dicarboxylic acids having preferably 3 to 6 carbon atoms, such as in particular acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, generally with 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms. containing alkanols, such as especially acrylic acid and methacrylic acid methyl, -ethyl, -n-butyl, -iso-butyl, -pentyl,-hexyl-, -heptyl-, -octyl-, -nonyl-, -decyl- and -2-ethylhexyl esters, fumaric and maleic dimethyl esters or -di-n-butyl esters, nitriles of α,β-monoethylene unsaturated carboxylic acids, such as acrylonitrile, methacrylonitrile, fumaric disinitrile, maleic disinitrile, and C4-8-conjugated dienes, such as 1,3-butadiene (butadiene) and isoprene. The aforementioned monomers generally constitute the main monomers, representing ≥ 50 wt.%, preferably ≥ 80 wt.%, and particularly preferably ≥ 90 wt.% of the total amount of monomers A3, or even constituting the total amount of monomers A3. As a rule, these monomers exhibit only moderate to low solubility in water under normal conditions [20 °C, 1 atm (absolute)].

[0022] Monomers A3 which exhibit increased water solubility under the aforementioned conditions are those which contain either at least one sulfonic acid group and / or its corresponding anion or at least one amino, amido, ureido or N-heterocyclic group and / or its nitrogen-protonated or alkylated ammonium derivatives. Examples include acrylamide and methacrylamide, as well as vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid and their water-soluble salts, and N-vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-vinylimidazole, 2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-dimethylamino)ethyl methacrylate, 2-(N,N-diethylamino)ethyl acrylate, 2-(N,N-diethylamino)ethyl methacrylate, 2-(N,N-diethylamino)ethyl methacrylate, 2-(N-tert-butylamino)ethyl methacrylate, N-(3-N',N'-dimethylaminopropyl)methacrylamide and 2-(1-imidazolin-2-onyl)ethyl methacrylate. Normally, the aforementioned water-soluble monomers A3 are present only as modifying monomers in amounts of ≤ 10 wt.-%, preferably ≤ 5 wt.% and particularly preferably ≤ 3 wt.%, based on the total amount of monomers A3.

[0023] Advantageously, for the production of polymers A or polymer mixture A, only those monomer mixtures are used as monomers A3 which are suitable for 90 to 100 wt.% Esters of acrylic and / or methacrylic acid with alkanols containing 1 to 12 carbon atoms, or 90 to 100 wt.% Styrene and / or butadiene, or 90 to 100 wt.% Vinyl acetate, vinyl propionate and / or ethylene contain.

[0024] According to the invention, the polymerized proportion of monomers A3 in polymer A or (or) polymer mixture A is 0 to 5 wt.%, advantageously ≤ 3 wt.% or ≤ 1 wt.% and ≥ 0.1 wt.%.

[0025] In a further advantageous embodiment, the polymer A or the polymer mixture A does not contain any monomers A3 polymerized into it. Accordingly, the polymer A or the polymer mixture A is composed of ≥ 95 wt.%, advantageously ≥ 97 wt.% or ≥ 99 wt.%, and in a further embodiment 100 wt.%, of monomers A1 + A2 in polymerized form.

[0026] If a polymer mixture A is used according to the invention, it can be obtained by conventionally combining two polymers A, each composed of acrylic acid (monomer A1) and maleic acid and / or maleic anhydride (monomer A2), and optionally monomers A3. In the case of the polymer mixture, the mixture has the monomer composition according to the invention.

[0027] The polymers A used according to the invention are generally produced by radical-initiated polymerization of the monomers A in an aqueous medium. Advantageously, the polymers A are produced in the presence of at least one radical chain regulator, with sulfur-, nitrogen-, and / or phosphorus-containing radical chain regulators exhibiting a solubility > 5 g / 100 g of water at 20 °C and 1 atm in deionized water being particularly preferred.

[0028] The basic preparation of polymers A is familiar to those skilled in the art (see, for example, A. Echte, Handbook of Technical Polymer Chemistry, Chapter 6, VCH, Weinheim, 1993 or B. Vollmert, Outline of Macromolecular Chemistry, Volume 1, E. Vollmert Verlag, Karlsruhe, 1988).

[0029] Examples of sulfur-containing radical chain regulators include mercaptoalkanols, such as 2-mercaptoethanol, 2-mercaptopropanol or 3-mercaptopropanol, alkali metal hydrogen sulfites, such as sodium hydrogen sulfite or potassium hydrogen sulfite, as well as thiosulfuric acid and their alkali metal salts or 3-mercapto-2-aminopropanoic acid (cysteine); nitrogen-containing radical chain regulators include, for example, hydroxylamine(ammonium) compounds, such as hydroxylammonium sulfate; and phosphorus-containing radical chain regulators include, for example, phosphorous acid, hypophosphorous acid, metaphosphorous acid, orthophosphoric acid, pyrophosphoric acid or polyphosphoric acid and their alkali metal salts, in particular their sodium or potassium salts, advantageously sodium hypophosphite or sodium dihydrogen phosphate.

[0030] The radical chain regulator is particularly advantageous when selected from hypophosphorous acid and its alkali metal salts, especially sodium hypophosphite, alkali metal hydrogen sulfites, especially sodium hydrogen sulfite, hydroxylaminium sulfate and / or 2-mercaptoethanol.

[0031] In the production of polymers A, it is advantageous to select the amount of radical chain regulator such that the weight-average molecular weight of polymers A is ≥ 1000 and ≤ 20000 g / mol, and particularly advantageously ≥ 2000 and ≤ 20000 g / mol. The required amount of radical chain regulator and the corresponding polymerization conditions are known to a person skilled in the art or can be determined by them in simple routine experiments.

[0032] According to a preferred embodiment, the polymer A has a weight-average molecular weight Mw ≥ 1000 and ≤ 20000 g / mol.

[0033] According to a particularly preferred embodiment, a polymer mixture A is selected which 10 to 30 wt.% a polymer A with a weight-average molecular weight > 7000 and < 20000 g / mol (polymer A1) and 70 to 90 wt.% of a polymer A with a weight-average molecular weight of 1000 to 5000 g / mol (polymer A2) relating to the total amount of polymer mixture A, contains, in particular consists of.

[0034] Polymer A1 and polymer A2 thus differ in their average molecular weight and may also differ in their composition of the monomers A1, A2 and A3, wherein the total amount of all monomers has the composition according to the invention.

[0035] The weight-average molecular weights of polymers A are determined in a manner familiar to those skilled in the art according to DIN EN ISO 13885-3 by gel permeation chromatography using a polyacrylic acid sodium salt as a standard.

[0036] Where the term "polymer / mixture A" is used below, this is intended to express that it applies to both polymer A and polymer mixture A.

[0037] In the production of the polymer P used according to the invention, it is possible to optionally introduce a partial or the entire amount of polymer / mixture A into the aqueous polymerization medium. Alternatively, it is also possible to add the entire amount or any remaining amount of polymer / mixture A together with the monomers M during the polymerization reaction. The entire amount or any remaining amount of polymer / mixture A can be added to the aqueous polymerization medium discontinuously in one or more portions or continuously with constant or varying flow rates. Advantageously, the entire amount of polymer / mixture A is introduced into the aqueous polymerization medium before the polymerization reaction of the monomers M is initiated. In a further advantageous embodiment, the polymer / mixture A is produced "in situ" in the polymerization medium for the polymerization of the monomers M.

[0038] It is important that the aqueous polymerization medium used in the production of polymer P may contain dispersing agents in addition to the polymer / mixture A. These agents keep both the monomer droplets and the dispersion particles of polymer P obtained through the radical-initiated polymerization of the monomers M dispersed within the aqueous phase, thus ensuring the stability of the resulting aqueous polymer composition. Suitable dispersing agents include both protective colloids commonly used in radical aqueous emulsion polymerizations and emulsifiers.

[0039] Suitable protective colloids include, for example, polyvinyl alcohols, cellulose derivatives, or copolymers containing vinylpyrrolidone. A detailed description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, pages 411 to 420, Georg Thieme Verlag, Stuttgart, 1961. Since the polymer / mixture A used according to the invention can also act as a protective colloid, it is advantageous not to use any additional protective colloids according to the invention.

[0040] Of course, mixtures of emulsifiers and / or protective colloids can also be used. Such emulsifiers are familiar to those skilled in the art and are described, for example, in WO 2017 / 140520 on pages 9 and 10.

[0041] If dispersing aids are used in the production of the aqueous dispersion of polymer P, the total amount of dispersing aids used, in particular emulsifiers, is 0.1 to 5 wt.%, preferably 1 to 3 wt.%, in each case based on the total amount of monomers M (total monomer amount M). In an advantageous embodiment, emulsifiers are used as the sole dispersing aids.

[0042] If dispersing agents are used in the preparation of the aqueous dispersion of polymer P, it is possible to introduce a portion or all of the dispersing agents as a component of the aqueous medium containing the polymer / mixture A. Alternatively, the total amount or any remaining amount of dispersing agents can be added during the polymerization reaction together with the monomers M. The total amount or any remaining amount of dispersing agents can be added to the aqueous polymerization medium discontinuously in one or more portions or continuously with constant or varying flow rates.

[0043] According to a preferred embodiment, the amount of polymer A is selected such that the ratio of polymer A to the total amount of monomers M is in the range of 10:90 to 50:50, preferably in the range of 20:80 to 40:60.

[0044] According to another preferred embodiment, the amount of polymer mixture A is selected such that the ratio of polymer mixture A to the total amount of monomers M is in the range of 10:90 to 50:50, preferably in the range of 20:80 to 40:60.

[0045] The essential aspect of the invention is that a monomer composition consists of 5 to 30 wt.%, one or more monomers M1, selected from esters of acrylic and / or methacrylic acid having 2 to 8 carbon atoms, alkanols 70 to 95 wt.% Styrene and / or methyl methacrylate (M2), and 0 to 10 wt.% at least one other ethylene unsaturated compound (M3) which is copolymerizable with the monomers M1 and M2, Each, based on the total amount of monomers M, is polymerized to a polymer P by means of radical emulsion polymerization, wherein the polymer P has a glass transition temperature T. G exhibits temperatures of ≥ 35 and ≤ 150 °C, preferably of ≥ 60 and ≤ 90 °C as measured according to DIN EN ISO 11357-2 (2013-09).

[0046] The carrying out of radical-initiated emulsion polymerizations of ethylene-unsaturated compounds (monomers) in an aqueous medium has been described extensively and is therefore sufficiently known to those skilled in the art [cf. Emulsion Polymerization in Encyclopedia of Polymer Science and Engineering, Vol. 8, pp. 659 ff. (1987); DC Blackley, in High Polymer Latices, Vol. 1, pp. 35 ff. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, Chapter 5, pp. 246 ff. (1972); D. Diederich, Chemie in unserer Zeit 24, pp. 135 to 142 (1990); Emulsion Polymerization, Interscience Publishers, New York (1965); DE-A 40 03 422 and Dispersions of Synthetic High Polymers, F. Hölscher, Springer-Verlag, Berlin (1969)].Radically initiated aqueous emulsion polymerization is usually carried out by dispersing the monomers in an aqueous medium, generally with the use of dispersing aids such as emulsifiers and / or protective colloids, and polymerizing them by means of at least one water-soluble radical polymerization initiator. Frequently, in the aqueous polymer dispersions obtained, the residual content of unreacted monomers is reduced by chemical and / or physical methods also known to the skilled person [see, for example, EP-A 771328, DE-A 19624299, DE-A 19621027, DE-A 19741184, DE-A 19741187, DE-A 19805122, DE-A 19828183, DE-A 19839199, DE-A 19840586 and 19847115], the polymer solids content is adjusted to a desired value by dilution or concentration, or other common additives, such as foam- or viscosity-modifying additives, are added to the aqueous polymer dispersion.The preparation of an aqueous dispersion of polymer P used according to the invention differs from this general procedure only in that the monomers M are polymerized in the presence of at least one polymer A or a polymer mixture A. It is understood that the preparation of polymers P within the scope of this document also includes seeding, step, and gradient processes familiar to those skilled in the art.

[0047] Advantageously, the esters of acrylic acid with alkanols having 2 to 8 C atoms (monomers M1) are chosen to be acrylic acid ethyl, -n-butyl, -iso-butyl, -pentyl, -hexyl, -heptyl, -octyl, and -2-ethylhexyl esters.

[0048] If the esters are of alcohols of biological origin, it is possible to increase the "biocarbon content" of polymer P. Suitable alcohols for the acrylic acid esters (M1) include, for example, isobutanol, isopentanol, and 2-octanol. An increased biocarbon content in this way reduces the proportion of fossil carbon and lowers the CO₂ emissions during the production of the polymer dispersion.

[0049] The term "biocarbon" indicates that the carbon is of biological origin and comes from a biomaterial / renewable resource. A renewable resource or biomaterial is an organic material in which the carbon originates from CO₂ that was recently (on a human timescale) fixed from the atmosphere through photosynthesis. A biomaterial (carbon of 100% natural origin) has an isotopic ratio of ¹⁴C / ¹²C greater than 10⁻¹², typically around 1.2 × 10⁻¹², while a fossil material has a zero ratio. In fact, the ¹⁴C isotope is formed in the atmosphere and then incorporated through photosynthesis over a period of a few decades. The half-life of ¹⁴C is 5730 years. Thus, materials derived from photosynthesis, generally plants, necessarily have a maximum content of the ¹⁴C isotope.The determination of the content of biomaterial or biocarbon can be carried out according to the standards ASTM D 6866-12, Method B (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04).

[0050] According to a preferred embodiment, the monomer M1 is selected from ethyl, propyl, n-butyl, i-butyl, hexyl and 2-ethylhexyl acrylate.

[0051] Monomers M2 are, according to the invention, styrene and / or methyl methacrylate.

[0052] Monomers M3 are ethylene-unsaturated compounds which can be copolymerized with monomers M1 and M2.Suitable materials include, in particular, monomers that are easily polymerizable via radicals, such as ethylene, vinylaromatic monomers such as α-methylstyrene, o-chlorostyrene or vinyltoluenes, vinyl halides such as vinyl chloride or vinylidene chloride, esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of α,β-monoethylene-unsaturated dicarboxylic acids having preferably 3 to 6 carbon atoms, such as, in particular, maleic acid, fumaric acid and itaconic acid, with alkanols generally having 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as, in particular, fumaric and maleic dimethyl esters or di-n-butyl esters, and nitriles of α,β-monoethylene-unsaturated Carboxylic acids, such as acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, and C 4-8 conjugated dienes, such as 1,3-butadiene and isoprene.

[0053] Monomers M3 that modify the polymer are those that contain either at least one acid group and / or its corresponding anion or at least one amino, amido, ureido or N-heterocyclic group and / or its nitrogen-protonated or alkylated ammonium derivatives. Examples include α,β-monoethylene unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, as well as vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid and their water-soluble salts, and N-vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 2-vinylimidazole, 2-aminoethyl acrylate, 2-aminoethyl methacrylate, 2-aminopropyl acrylate, 2-aminopropyl methacrylate, 3-aminopropyl acrylate, 3-aminopropyl methacrylate, 2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-dimethylamino)ethyl methacrylate, 2-(N,N-diethylamino)ethyl acrylate. 2-(N,N-diethylamino)ethyl methacrylate, 2-(N-tert.-Butylamino)ethyl methacrylate, N-(3-N',N'-dimethylaminopropyl)methacrylamide and 2-(1-imidazolin-2-onyl)ethyl methacrylate.

[0054] The aforementioned monomers M3 may be included as modifying monomers. If included, they are used in amounts ≤ 10 wt.% and preferably ≤ 5 wt.%, based on the total amount of monomers P.

[0055] Monomers M3, which typically increase the internal strength of polymer matrix films, usually contain at least one epoxy, hydroxy, N-methylol, or carbonyl group, or at least two non-conjugated ethylene-unsaturated double bonds. Examples include monomers containing two vinyl groups, monomers containing two vinylidene groups, and monomers containing two alkenyl groups. Diesters of dihydric alcohols with α,β-monoethylene-unsaturated monocarboxylic acids are particularly advantageous, with acrylic and methacrylic acids being preferred.Examples of such monomers containing two non-conjugated ethylene-unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates, such as ethylene glycol diacrylate, 1,2-propylene glycol diacrylate, 1,3-propylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylates and ethylene glycol dimethacrylate, 1,2-propylene glycol dimethacrylate, 1,3-propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate as well as 1,2-, 1,3- or 1,4-divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, methylene bisacrylamide, cyclopentadienyl acrylate. Triallyl cyanurate or triallyl isocyanurate. Also of particular importance in this context are the methacrylic acid and acrylic acid C1-C8 hydroxyalkyl esters such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxy- or 4-hydroxybutyl acrylate and methacrylate, as well as compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate.The aforementioned monomers are frequently used in amounts ≤ 5 wt.%, but preferably in amounts ≤ 1 wt.%, in each case based on the total amount of monomers P.

[0056] Preferably, the polymer P is obtainable by radical-initiated emulsion polymerization of a monomer composition consisting of 5 to 30 wt.%, one or more monomers M1, selected from esters of acrylic and / or methacrylic acid having 2 to 8 carbon atoms, in particular esters of acrylic acid having 2 to 8 carbon atoms, 70 to 95 wt.% or 70 to 94.9 wt% styrene and / or methyl methacrylate (M2), 0.1 to 10 wt.% at least one further ethylene unsaturated compound (M3) which is copolymerizable with the monomers M1 and M2, of which 0.1 to 5.0 wt% based on the total monomers M is glycidyl acrylate and / or glycidyl methacrylate, each in relation to the total amount of monomers M.

[0057] The polymer P is particularly preferred, obtainable by radical-initiated emulsion polymerization of a monomer composition consisting of 5 to 25 wt.% Ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, hexyl acrylate and / or 2-ethylhexyl acrylate (M1), 70 to 94.9 wt.% Styrene and / or methyl methacrylate (M2), 0.1 to 5.0 wt.% Glycidyl acrylate and / or glycidyl methacrylate (M3a), 0 to 5.0 wt.% Acrylic acid, methacrylic acid, 2-hydroxyethyl, 2-hydroxypropyl and / or 3-hydroxypropyl acrylate and / or methacrylate (M3b), 0 to 2.0 wt.% 1,4-Butylene glycol diacrylate and methacrylate, 1,2-, 1,3- and 1,4-divinylbenzene, allyl acrylate and / or allyl methacrylate (M3c) where the amounts of the monomers M add up to 100 wt.%.

[0058] The polymer P is particularly preferred, obtainable by radical-initiated emulsion polymerization of a monomer composition consisting of 5 to 20 wt.% Ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, hexyl acrylate and / or 2-ethylhexyl acrylate (M1), 70 to 94.9 wt.% Styrene and / or methyl methacrylate (M2), 0.1 to 5.0 wt.% Glycidyl acrylate and / or glycidyl methacrylate (M3a), 0 to 5.0 wt.% Acrylic acid, methacrylic acid, 2-hydroxyethyl, 2-hydroxypropyl and / or 3-hydroxypropyl acrylate and / or 2-hydroxyethyl, 2-hydroxypropyl and / or 3-hydroxypropyl methacrylate (M3b), 0 to 2.0 wt.% 1,4-Butylene glycol diacrylate and methacrylate, 1,2-, 1,3- and 1,4-divinylbenzene, allyl acrylate and / or allyl methacrylate (M3c) where the amounts of the monomers M add up to 100 wt.%.

[0059] The radical-initiated aqueous emulsion polymerization for the production of polymers P is generally carried out in the presence of 0.1 to 5 wt.%, preferably 0.1 to 4 wt.%, and particularly 0.1 to 3 wt.%, based on the total amount of monomers M, of a radical polymerization initiator. Suitable radical initiators include all those capable of triggering a radical aqueous emulsion polymerization. These can, in principle, be peroxides or azo compounds. Redox initiator systems are also suitable. Peroxides can, in principle, be inorganic peroxides, such as hydrogen peroxide or peroxodisulfates, such as the mono- or di-alkali metal or ammonium salts of peroxodisulfuric acid, for example, their mono- and disodium, potassium, or ammonium salts, or organic peroxides, such as alkyl hydroperoxides, for example, tert-1.-Butyl, p-menthyl, or cumyl hydroperoxide, as well as dialkyl or diaryl peroxides, such as di-tert-butyl or di-cumyl peroxide, are used. The azo compounds primarily employed are 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(amidinopropyl) dihydrochloride (AIBA, equivalent to V-50 from Wako Chemicals). Naturally, so-called redox initiator systems can also be used as radical initiators. The peroxides mentioned above are essentially the only suitable oxidizing agents for redox initiator systems.Suitable reducing agents include sulfur compounds with low oxidation states, such as alkali sulfites (e.g., potassium and / or sodium sulfite), alkali hydrogen sulfites (e.g., potassium and / or sodium hydrogen sulfite), alkali metabisulfites (e.g., potassium and / or sodium metabisulfite), formaldehyde sulfoxylates (e.g., potassium and / or sodium formaldehyde sulfoxylate), alkali salts (especially potassium and / or sodium salts), aliphatic sulfinic acids, alkali metal hydrogen sulfides (e.g., potassium and / or sodium hydrogen sulfide), salts of polyvalent metals (e.g., iron(II) sulfate, iron(II) ammonium sulfate, iron(II) phosphate), enediols (e.g., dihydroxymaleic acid, benzoin and / or ascorbic acid), and reducing saccharides (e.g., sorbose, glucose, fructose and / or dihydroxyacetone).

[0060] In addition to the seedless production method, emulsion polymerization can be used to produce polymers P using the seed latex method or in the presence of in-situ produced seed latex to adjust the polymer particle size. Methods for this are known to those skilled in the art and can be found in the prior art (see, for example, EP-B 40 419, EP-A 567 812, EP-A 614 922, and 'Encyclopedia of Polymer Science and Technology', Vol. 5, page 847, John Wiley & Sons Inc., New York, 1966). For example, the prior art recommends introducing a defined, finely divided seed polymer dispersion in the aqueous polymerization medium in the semi-continuous feed process and then polymerizing the monomers M in the presence of the seed latex. Here, the seed polymer particles act as 'polymerization nuclei' and decouple polymer particle formation and growth.During emulsion polymerization, additional seed latex can, in principle, be added directly to the aqueous polymerization medium. This achieves broad size distributions of the polymer particles, which are often desirable, particularly in polymer dispersions with a high solids content (see, for example, DE-A 4213965). Instead of adding a defined seed latex, it can also be generated in situ. For this purpose, for example, a portion of the monomers M and the radical initiator used for polymerization is placed together with a portion or all of the polymer A and, if necessary, additional dispersing agents, and heated to reaction temperature, resulting in a relatively fine polymer seed. Subsequently, the actual polymerization is carried out in the same aqueous polymerization medium using the feed method (see also DE-A 4213965).

[0061] Advantageously, the polymers P are produced by radical-initiated aqueous emulsion polymerization at a reaction temperature in the range of 0 to 170 °C, although temperatures of 70 to 120 °C and especially 80 to 100 °C are particularly preferred. The radical aqueous emulsion polymerization can be carried out at a pressure of less than, equal to, or greater than 1 atm (absolute). Preferably, volatile monomers such as ethylene, butadiene, or vinyl chloride are polymerized under elevated pressure. The pressure can be 1.2, 1.5, 2, 5, 10, 15 bar (gauge pressure) or even higher. If emulsion polymerizations are carried out under reduced pressure, pressures of 950 mbar, frequently 900 mbar, and often 850 mbar (absolute) are used.The radical aqueous emulsion polymerization of the monomers is advantageously carried out at 1 atm (= atmospheric pressure = 1.013 bar absolute) or under increased pressure under an inert gas atmosphere, such as nitrogen or argon.

[0062] In radical-initiated aqueous emulsion polymerization, the aqueous polymerization medium can, in principle, also contain minor amounts (< 5 wt%) of water-soluble organic solvents, such as methanol, ethanol, isopropanol, butanols, pentanols, and even acetone, etc. However, radical-initiated aqueous emulsion polymerization preferably takes place in the absence of such solvents.

[0063] The polymers P used according to the invention have a glass transition temperature Tg ≥ 35 °C and ≤ 150 °C measured according to DIN EN ISO 11357-2 (2013-09). Advantageously, the glass transition temperature of the polymers P is in the range ≥ 40 °C and ≤ 110 °C, and particularly advantageously in the range ≥ 60 °C and ≤ 90 °C.

[0064] It is also important that, according to Fox (TG Fox, Bull. Am. Phys. Soc. 1956 [Ser. II] 1, page 123 and according to Ullmann's Encyclopädie der technischen Chemie, Vol. 19, page 18, 4th edition, Verlag Chemie, Weinheim, 1980), the glass transition temperature of at most weakly cross-linked copolymers can be estimated to a good approximation by the following equation. 1 / Tg = x 1 / Tg 1 + x 2 / Tg 2 + … . x n / Tg n , where x₁, x₂, ..., xₙ are the mass fractions of monomers 1, 2, ..., n, and Tg₁<, Tg₂<, ..., Tgₙ< are the glass transition temperatures in Kelvin of the homopolymers composed of only one of monomers 1, 2, ..., n. The glass transition temperatures of these homopolymers of most ethylene-unsaturated monomers are known (or can be determined experimentally in a simple, known manner) and are listed, for example, in Brandrup, J.; Immergut, EH; Grulke, EA; Abe, A.; Bloch, DR: Polymer Handbook, 4th Edition, Wiley-VCH 2003, and in Penzel, E., Ballard, N. and Asua, JM (2021). Polyacrylates. In Ullmann's Encyclopedia of Industrial Chemistry.

[0065] The aqueous dispersions of polymer P accessible by emulsion polymerization typically have a solids content of ≥ 30 and ≤ 70 wt.%, frequently ≥ 40 and ≤ 68 wt.% and often ≥ 45 and ≤ 65 wt.%, in each case based on the aqueous polymer dispersion.

[0066] Advantageously, the polymers P are available in the form of particles with a mean particle diameter ≥ 10 and ≤ 1000 nm, advantageously ≥ 30 and ≤ 600 nm and particularly advantageously ≥ 100 to ≤ 500 nm, determined by the quasi-elastic light scattering method (ISO standard 13 321; cumulant z-average).

[0067] In the production of the polymer / fiber composite, ≥ 1 and ≤ 50 g and with particular advantage ≥ 5 and ≤ 25 g of polymer dispersion P (solid) (calculated as the sum of polymers A or polymer mixture A and the total amount of monomers M), based on 100 g of fibrous substrate, are advantageously used.

[0068] To increase the strength of the composite without losing its thermoformability, a preferred embodiment allows the dispersion of polymer P to contain ≤3 wt.%, preferably 0.1 to 3 wt.%, of an amine having at least 2 hydroxyl groups, based on polymer dispersion P (solid).

[0069] Suitable amines containing at least two hydroxyl groups are secondary or tertiary alkylamines with C1-C20 alkyl groups, which may optionally be unsaturated and / or interrupted by oxy groups. These amines may have two, three, or four hydroxyl groups.

[0070] Advantageously suitable are β-hydroxyalkylamines of the general formula R 1< -NR 2< (R 3< ), in which R 1< represents a hydrogen atom, a C 1 to C 10 alkyl group, a C 1 -C 10 hydroxyalkyl group which may be interrupted by ethylene oxide and / or propylene oxide units, and R 2< and R 3< independently represent a C 1 -C 10 hydroxyalkyl group.

[0071] Particularly preferred are diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, especially triethanolamine.

[0072] According to a further preferred embodiment, the aqueous polymer dispersion P does not contain triethanolamine, in particular no amine having at least 2 hydroxyl groups.

[0073] According to the inventive method, polymer / fiber composites are particularly accessible with a basis weight of ≥ 1000 and ≤ 30000 g / m², more advantageously ≥ 1000 and ≤ 20000 g / m², and more advantageously ≥ 1000 and ≤ 10000 g / m². In a preferred embodiment, the polymer / fiber composites obtainable according to the inventive method are planar, while in a further preferred embodiment they have a non-planar three-dimensional structure.

[0074] The invention also includes polymer / fiber composites as obtained according to the inventive method.

[0075] Similarly, the use of a polymer / fiber composite according to the invention for the production of a polymer / fiber molded part according to the invention is also included, which differs in its shape from the polymer / fiber composite used.

[0076] Accordingly, the invention also includes a method for producing a polymer / fiber molded part, characterized in that the polymer / fiber composite according to the invention is heated to a temperature ≥ the glass transition temperature T g of the polymer P and is brought into the desired shape of the polymer / fiber molded part at a temperature ≥ the glass transition temperature T g of the polymer P and then the resulting polymer / fiber molded part is cooled to a temperature < the glass transition temperature T g of the polymer P while retaining its shape.

[0077] According to the invention, the polymer / fiber composite is heated to a temperature that corresponds at least to the glass transition temperature Tg of the polymer P. Advantageously, the polymer / fiber composite is heated to a temperature Tg + ≥ 10 K and, with particular advantage, Tg + ≥ 30 K, i.e., a temperature that is at least 10, preferably 30, Kelvin above the glass transition temperature of the polymer P.

[0078] Furthermore, it is important that in one embodiment, the polymer / fiber molded part is manufactured using a heated molding press whose contact surface has a temperature ≥ Tg and whose shape corresponds to the negative form of the polymer / fiber molded part, and which cools outside the molding press. In this embodiment, the heating and forming processes take place in the heated molding press. Of course, according to the invention, it is also possible for the polymer / fiber composite to be heated to a temperature ≥ Tg outside the molding press and then formed into the polymer / fiber molded part in the molding press without further heating. In this embodiment, the heating and forming processes take place separately.

[0079] In an advantageous embodiment, the method according to the invention is carried out in such a way that an intermediate process step is performed before or after the heating process but before the deformation step, in which a planar decorative material is applied to one and / or the other surface of the polymer / fiber composite.

[0080] The decorative material that can be used according to the invention is advantageously a textile fabric, such as a nonwoven, woven or knitted fabric made of natural or synthetic fibers, a plastic film, such as a thermoplastic polyvinyl chloride, polyolefin or polyester film, a foamed fabric, such as a fabric made of polyolefin or polyurethane foam, a foamed fabric which in turn is coated (laminated) on the surface not coming into contact with the heated polymer / fiber composite with a textile fabric, a plastic film or another foamed fabric, or a wood veneer.

[0081] The sheet-like decorative material typically has a thickness of ≤ 10 mm. If the sheet-like decorative material is a textile fabric or a plastic film, its thickness is typically ≤ 3 mm, often advantageously ≤ 2 mm, and frequently, and particularly advantageously, ≤ 1 mm. However, if the sheet-like decorative material is a foamed fabric or a coated (laminated) foamed fabric, its thickness is often ≤ 8 mm, often ≤ 5 mm, and particularly often ≤ 3 mm. If the sheet-like decorative material is a wood veneer, its thickness is typically ≤ 3 mm, often advantageously ≤ 2 mm, and frequently, and particularly advantageously, ≤ 1 mm.

[0082] According to the invention, the polymer / fiber molded parts accessible by the aforementioned method are therefore also included.

[0083] According to the invention, it is also important that both the process for producing the polymer / fiber composite and the process for producing the polymer / fiber molded part can be carried out continuously or discontinuously.

[0084] The polymer / fiber molded parts accessible according to the invention exhibit good thermal dimensional stability and are therefore advantageously suited as components in vehicle construction, such as door inserts, door trim carriers, knee guards, glove compartments, parcel shelves, sun visors, center consoles, trunk linings or seat back linings, in buildings, such as room dividers, partition walls, ceiling panels or wall trim parts, and in furniture as furniture molded parts, such as seat or back surfaces, with the use as wall trim parts, furniture molded parts or interior components in vehicle construction being particularly preferred.

[0085] Furthermore, the polymer / fiber molded parts according to the invention exhibit good dimensional stability in humid climates. They are therefore advantageously suited for bathroom or kitchen furniture, or furniture in general, which is exposed to higher levels of water vapor, such as in climates with high humidity.

[0086] The invention will be explained by the following non-limiting examples. Examples Measurement methods:

[0087] The solids content was generally determined using a moisture analyzer from Mettler Toledo by drying 0.5 to 1 g of a obtained polymer dispersion or polymer solution at 140 °C until constant weight was achieved.

[0088] The glass transition temperature of polymer P was generally determined using a Q 2000 differential calorimeter from TA Instruments. The heating rate was 10 K per minute.

[0089] The number-mean particle size of the dispersion particles was generally determined by dynamic light scattering of a 0.005 to 0.01 wt% aqueous dispersion at 23 °C using the Malvern Instruments IIC autosizer, England. The mean diameter of the cumulant z-average of the measured autocorrelation function (ISO standard 13321) is given.

[0090] The pH values ​​were generally determined by measuring a sample with a pH electrode from the company Schott at room temperature.

[0091] The viscosity was determined according to the Brookfield method (ISO 2555, 1989) at 23 °C.

[0092] The molecular weight of polymer solutions A1, A2 and A3 was determined by gel permeation chromatography using a sodium polyacrylic acid salt as a standard, employing two Tosoh TSKgel G 3000 PWXL columns connected in series at a temperature of 35 °C, an eluent (deionized water with 0.01 mol / l phosphate buffer pH 7.4 and 0.01 mol / l NaN3), a flow rate of 0.5 ml per minute, an injection volume of 100 µl, a concentration of the injected solution of 1 to 2 mg per ml, and a DRI detector from Agilent Technologies GmbH. Materials used:

[0093] Polymer solution A1: 50 wt% aqueous solution of an acrylic acid / maleic acid copolymer (weight ratio acrylic acid / maleic acid in the polymer 50:50) with a weight-averaged molecular weight of 3,000 g / mol Polymer solution A2: 44 wt% aqueous solution of an acrylic acid / maleic acid copolymer (weight ratio acrylic acid / maleic acid in the polymer 70:30) with a weight-averaged molecular weight of 10,000 g / mol Polymer solution A3: 49 wt% aqueous solution of an acrylic acid homopolymer with a weight-averaged molecular weight of 5,000 g / mol Example 1: Preparation of an aqueous polymer P dispersion in the presence of a polymer mixture A (dispersion D1)

[0094] In a 4 L glass vessel equipped with an anchor stirrer, reflux condenser, and dosing device, 378 g of deionized water, 792 g of polymer solution A1, 150 g of polymer solution A2, and 18.6 g of triethanolamine were placed at 23 °C. The polymer mixture A (polymer A1 + polymer A2) is thus composed of monomers A1 / A2 in a weight ratio of 54 / 46 (acrylic acid / maleic acid).

[0095] To this mixture, 66 g of a 25 wt% aqueous sodium hydroxide solution were then added dropwise via a dropping funnel, and the mixture was heated to 94 °C under a nitrogen atmosphere at atmospheric pressure (1.013 bar absolute). After reaching the target temperature, 10 wt parts of feed 1 were added within one minute while stirring. Subsequently, starting simultaneously and maintaining a polymerization temperature of 93 °C, the remainder of feed 1 and the entire quantity of feed 2 were added. Feed 1 was added continuously at a constant rate over 165 minutes, and feed 2 over 150 minutes. Inlet 1: 220 g a 7 wt% aqueous solution of sodium peroxodisulfate. Inlet 2: homogeneous emulsion of 298 g deionized water 27,5 g a 28 wt% aqueous solution of sodium lauryl ether sulfate (Disponil ®< FES 27; product of BASF SE), 22 g a 15 wt% aqueous solution of sodium dodecyl sulfate (Disponil ®< SDS 15; product of BASF SE), 132 g n-Butyl acrylate, 233 g Methyl methacrylate 702 g Styrene and 33 g Glycidyl methacrylate.

[0096] After the addition of feed 1 was completed, stirring continued for 5 minutes while cooling to 90 °C. Stirring then continued for a further 45 minutes at 90 °C. The polymerization mixture was then cooled to room temperature and adjusted to pH 2.8 by adding 32 g of a 25 wt% aqueous sodium hydroxide solution dropwise.

[0097] After filtration through a 125 µm filter, the resulting aqueous polymer dispersion exhibited a solids content of 53.0 wt% and a viscosity of 84 mPas. The number-mean particle size was determined to be 317 nm and the glass transition temperature of the emulsion polymer to be 79 °C. Example 2: Preparation of an aqueous polymer P dispersion in the presence of a polymer mixture A (dispersion D2)

[0098] In a 4 L glass vessel with anchor stirrer, reflux condenser and dosing device, 322 g of deionized water, 792 g of polymer solution A1, and 198 g of polymer solution A2 were placed at 23 °C.

[0099] To this polymer mixture A, 100 g of a 25 wt% aqueous sodium hydroxide solution were then added dropwise via a dropping funnel, and the mixture was heated to 94 °C under a nitrogen atmosphere at atmospheric pressure (1.013 bar absolute). The process was then continued as in Example 1, using the same feed compositions and quantities.

[0100] After filtration through a 125 µm filter, the resulting aqueous polymer dispersion exhibited a solids content of 53.0% and a viscosity of 106 mPas. The number-mean particle size was determined to be 325 nm and the glass transition temperature of the emulsion polymer to be 78 °C. Example 3: Preparation of an aqueous polymer P dispersion in the presence of polymer A1 (dispersion D3)

[0101] In a 4 L glass vessel with anchor stirrer, reflux condenser and dosing device, 319 g of deionized water and 595 g of polymer solution A1 were placed at 23 °C.

[0102] To this mixture, 110 g of a 25 wt% aqueous sodium hydroxide solution were then added dropwise via a dropping funnel, and the mixture was heated to 94 °C under a nitrogen atmosphere at atmospheric pressure (1.013 bar absolute). After reaching the temperature, 10 wt parts of feed 1 were added within one minute while stirring. Subsequently, starting simultaneously and maintaining a polymerization temperature of 93 °C, the remainder of feed 1 and the entire quantity of feed 2 were added. Feed 1 was added continuously at a constant rate over 165 minutes, and feed 2 over 150 minutes. Inlet 1: 180 g a 7 wt% aqueous solution of sodium peroxodisulfate. Inlet 2: homogeneous emulsion of 267 g deionized water 21,4 g a 28 wt% aqueous solution of sodium lauryl ether sulfate (Disponil ®< FES 27; product of BASF SE), 16 g a 15 wt% aqueous solution of sodium dodecyl sulfate (Disponil SDS 15; product of BASF SE), 108 g n-Butyl acrylate, 199 g Methyl methacrylate and 596 g Styrene

[0103] After the addition of feed 1 was completed, stirring continued for 5 minutes while cooling to 90 °C. Stirring then continued for a further 45 minutes at 90 °C. The polymerization mixture was then cooled to room temperature and adjusted to pH 2.8 by adding 32 g of a 25 wt% aqueous sodium hydroxide solution dropwise.

[0104] After filtration through a 125 µm filter, the resulting aqueous polymer dispersion exhibited a solids content of 52.5% and a viscosity of 70 mPas. The number-mean particle size was determined to be 325 nm and the glass transition temperature of the emulsion polymer to be 80 °C. Example 4: Preparation of an aqueous polymer P dispersion in the presence of polymer A3 (reference dispersion V1 - not according to the invention)

[0105] In a 4 L glass vessel with anchor stirrer, reflux condenser and dosing device, 433 g of deionized water and 941 g of polymer solution A3 were placed at 23 °C.

[0106] To this mixture, 96 g of a 25 wt% aqueous sodium hydroxide solution were then added dropwise via a dropping funnel, and the mixture was heated to 94 °C under a nitrogen atmosphere at atmospheric pressure (1.013 bar absolute). After reaching the target temperature, 10 wt parts of feed 1 were added within one minute while stirring. Subsequently, starting simultaneously and maintaining a polymerization temperature of 93 °C, the remainder of feed 1 and the entire quantity of feed 2 were added. Feed 1 was added continuously at a constant rate over 165 minutes, and feed 2 over 150 minutes. Inlet 1: 160 g of a 7 wt% aqueous solution of sodium peroxodisulfate. Inlet 2: homogeneous emulsion of 292 g deionized water 28,6 g a 28 wt% aqueous solution of sodium lauryl ether sulfate (Disponil ®< FES 27; product of BASF SE), 21,3 g a 15 wt% aqueous solution of sodium dodecyl sulfate (Disponil ®< SDS 15; product of BASF SE), 80 g n-Butyl acrylate, 763 g Methyl methacrylate and 277 g Styrene

[0107] After the addition of feed 1 was completed, the mixture was stirred for another 5 minutes and cooled to 90 °C. The polymerization mixture was then stirred for a further 45 minutes at 90 °C and subsequently cooled to room temperature.

[0108] After filtration through a 125 µm filter, the resulting aqueous polymer dispersion exhibited a solids content of 51.9%, a pH of 3.5, and a viscosity of 120 mPas. The number-mean particle size was determined to be 446 nm, and the glass transition temperature of the emulsion polymer to be 92 °C. Example 5: Preparation of an aqueous polymer P dispersion in the presence of polymer A3 (reference dispersion V2 - not according to the invention)

[0109] In a 4 L glass vessel with anchor stirrer, reflux condenser and dosing device, 408 g of deionized water and 1041 g of polymer solution A3 were placed at 23 °C.

[0110] To this mixture, 102 g of a 25 wt% aqueous sodium hydroxide solution were then added dropwise via a dropping funnel, and the mixture was heated to 94 °C under a nitrogen atmosphere at atmospheric pressure (1.013 bar absolute). After reaching the target temperature, 10 wt parts of feed 1 were added within one minute while stirring. Subsequently, starting simultaneously and maintaining a polymerization temperature of 93 °C, the remainder of feed 1 and the entire quantity of feed 2 were added. Feed 1 was added continuously at a constant rate over 165 minutes, and feed 2 over 150 minutes. Inlet 1: 170 g of a 7 wt% aqueous solution of sodium peroxodisulfate. Inlet 2: homogeneous emulsion of 329 g deionized water 30,4 g a 28 wt% aqueous solution of sodium lauryl ether sulfate (Disponil ®< FES 27; product of BASF SE), 22,7 g a 15 wt% aqueous solution of sodium dodecyl sulfate (Disponil ®< SDS 15; product of BASF SE), 85 g n-Butyl acrylate, 621 g Methyl methacrylate and 415 g Styrene

[0111] After the addition of feed 1 was completed, the mixture was stirred for another 5 minutes and cooled to 90 °C. The polymerization mixture was then stirred for a further 45 minutes at 90 °C and subsequently cooled to room temperature.

[0112] After filtration through a 125 µm filter, the resulting aqueous polymer dispersion exhibited a solids content of 52.3%, a pH of 3.5, and a viscosity of 134 mPas. The number-mean particle size was determined to be 352 nm, and the glass transition temperature of the emulsion polymer to be 86 °C. Example 6

[0113] Furthermore, the dispersion of example 3 of WO 01 / 27163 was reproduced (comparative dispersion V3 - not according to the invention). General regulations for the production of fiberboard (polymer / fiber composite)

[0114] The tests were conducted using a 12-inch refiner from Antriz and an associated blowline. The refiner was operated at 160 to 170 °C and an internal pressure of 5 to 6 bar (gauge). The gap between the two grinding plates was 0.3 mm, with one of the grinding plates rotating at 3000 revolutions per minute. The blowline (steel pipe), connected to the refiner via a flange, had an inner diameter of 3 cm and a length of 30 m. Aqueous binders were injected into the blowline at 2 bar (gauge) through a 0.2 mm nozzle embedded in the blowline wall 50 cm from the refiner outlet / blowline inlet. At the end of the blowline was a cyclone separator, which further dried the coated wood fibers, cooled them to a temperature of approximately 80 °C, and collected them in an open container.

[0115] For the investigations, spruce wood chips pretreated with 160 to 170 °C hot water / steam at 5 to 6 bar overpressure in a cooker were used, whereby the mass flow of wood chips into the refiner (or wood fibers into the blowline) was set to 30 kg per hour.

[0116] The binders used were dispersions D1, D2, and D3, as well as the reference dispersions V1, V2, and V3. The binders were injected into the blowline via a 0.2 mm nozzle using an eccentric screw pump at a pressure of 2 bar (gauge pressure), with the mass flow rates adjusted to 4.8 kg of binder (calculated as solids) per hour. A 2-hour test was conducted for each binder under continuous steady-state conditions, during which time the wood fibers sprayed with the respective binder were collected in the open container. The proportion of polymer P (solids) relative to the fibers was 15 wt%.

[0117] Using the "glued" fibers obtained from the blowline according to the aforementioned experimental procedure, two semi-finished products, each 8.5 mm thick and 22 x 22 cm long x wide, with a target density of 0.65 g / cm³, were produced. For this purpose, 268 g of the obtained fibers (residual moisture content approx. 8 wt% based on dry fibers, average fiber length approx. 2 mm, average fiber thickness approx. 0.4 mm) were evenly distributed into a horizontally positioned wooden frame with internal dimensions of 22 x 22 x 30 cm (L / W / H). Subsequently, a 22 x 22 cm wooden board was placed horizontally on top of the fiber layer in the wooden frame and pre-compacted to a height of 5 cm using a central tamper. The resulting fiber cake was then removed from the wooden frame, covered with a release paper on both square surfaces, and compacted at 180 °C under pressure with a pressing time factor of 12 seconds per millimeter of composite thickness to a thickness of 8.5 mm.The resulting fiberboards were then allowed to cool to room temperature outside the printing press. These fiberboards (polymer / fiber composite) serve as semi-finished products for subsequent compaction at 140 °C or 180 °C with a pressing time factor of 12 seconds per millimeter of mold thickness to simulate subsequent deformation and to test the water resistance and other properties of the resulting "molds".

[0118] Depending on the binder used, the resulting molded bodies are called FPD1 (fiberboard with dispersion D1), FPD2 (fiberboard with dispersion D2), FPD3 (fiberboard with dispersion D3), FPV1 (fiberboard with comparative dispersion V1), FPV2 (fiberboard with comparative dispersion V2) and FPV3. Application-related study

[0119] Determination of water resistance and mechanical properties: After 24 hours of storage under standard climate conditions, the resulting semi-finished products are subjected to further compaction (corresponding to forming) at 140 °C and at 180 °C. During this process, the semi-finished products, with a density of 0.65 g / cm³, are further compacted to a density of 0.90 g / cm³.

[0120] The resulting fiberboards (molded specimens) (15 wt% polymer content based on the fiberboard) are stored for 24 hours under standard climate conditions at 20 °C / 65% relative humidity and then tested. To determine water absorption and thickness swelling, 5x5 cm specimens are cut and their thicknesses are measured according to DIN EN 325 using a measuring device in the center of the square specimen area to an accuracy of 0.01 mm. The density of the boards is determined by the ratio of the mass of the fiberboards to their volume, which can be calculated from the length, width, and thickness of the fiberboards. The water absorption of the wood fiberboards is determined as the relative weight gain, and the thickness swelling as the relative increase in thickness of 5x5 cm specimens after 24 hours of storage in demineralized water according to DIN EN 317. The flexural modulus and the bending strength at 23 °C are measured using a three-point bending test according to DIN EN 310. Table 1: Results of the tests of the molded bodies made from glued wood fibers with the binders from D1, D2, D3, V1, V2 and V3 pressed at 140 °C Molded body FPD1 FPD2 FPD3 FPV1 FPV2 FPV3 binder D1 D2 D3 V1 V2 V3 Panel thickness [mm] 6,00 6,20 6,03 5,98 6,00 6,10 Density [g / cm³< ] 0,85 0,86 0,83 0,85 0,82 0,83 Water absorption after 2 hours [%] 29 27 31 29 18 21 Standard deviation 2 2 2 2 1 1 Water absorption after 24 hours [%] 124 112 130 145 152 240 Standard deviation [%] 5 4 6 9 11 15 Thickness swelling after 2 hours [%] 16 17 15 16 10 9 Standard deviation [%] 1 1 1 1 0 1 Thickness swelling after 24 hours [%] 54 55 58 124 135 187 Molded body FPD1 FPD2 FPD3 FPV1 FPV2 FPV3 Standard deviation [%] 3 2 3 10 12 17 Bending E-modulus ISO 178 [N / mm²] 2859 2932 2786 2859 3393 2687 Standard deviation [N / mm²<] 81 78 92 101 106 171 Flexural strength [N / mm²] 27 28 25 27 37 29 Standard deviation [N / mm²<] 2 2 3 2 3 4 Width [mm] 15,2 15,1 15,3 15,2 15,1 14,9 Span [mm] 78 78 78 78 78 78 Table 2: Results of the tests of the manufactured comparison panels (molded bodies) made of glued wood fibers with the binders from D1, D2, D3, V1, V2 and V3 pressed at 180 °C Molded body FPD1 FPD2 FPD3 FPV1 FPV2 FPV3 binder D1 D2 D3 V1 V2 V3 Panel thickness [mm] 6,0 6,0 6,03 6,03 5,98 6,2 Density [g / cm³< ] 0,84 0,85 0,84 0,86 0,83 0,83 Water absorption after 2 hours [%] 21 24 25 29 27 35 Standard deviation 1 1 3 2 1 2 Water absorption after 24 hours [%] 74 71 87 124 129 112 Standard deviation [%] 3 8 6 5 7 10 Thickness swelling after 2 hours [%] 9 10 12 22 24 18 Standard deviation [%] 8 0 6 1 0 1 Thickness swelling after 24 hours [%] 33 35 38 87 90 56 Standard deviation [%] 1 4 2 3 6 2 Bending E-modulus ISO 178 [N / mm²] 853 961 2744 2859 3393 2687 Standard deviation [N / mm²<] 86 79 74 81 106 171 Flexural strength [N / mm²] 30 32 28 28 27 35 Standard deviation [N / mm²<] 1 1 1 2 3 4 Width [mm] 15,1 15 15,4 15,2 15,1 14,9 Span [mm] 78 78 78 78 78 78

[0121] In FPV3, it is observed that only at higher temperatures, 180°C compared to 140°C, does the crosslinking of the system lead to an improvement in water resistance. In contrast, the examples according to the invention exhibit lower values ​​for water absorption and thickness swelling even at lower temperatures. While the comparative binders V1 and V2 perform worse at 140°C and improve with increasing temperature, they do not reach the performance level of the examples according to the invention.

Claims

1. A process for producing a thermoformable polymer / fiber composite using a polymer P and a fibrous substrate, where the latter are particles having a ratio of their longest extent to their shortest extent of at least 3, where • the fibrous substrate is introduced into a gas stream, then • the fibrous substrate in the gas stream is contacted with an aqueous dispersion of a polymer P having a glass transition temperature Tg ≥ 35 and ≤ 150°C measured to DIN EN ISO 11357-2 (2013-09), then • the fibrous substrate that has been contacted with the aqueous dispersion of the polymer P is dried in the gas stream and then deposited, then • the deposited fibrous substrate obtained is converted to a fiber web, and then • the resultant fiber web is consolidated at a temperature ≥ the glass transition temperature Tg of polymer P to give the polymer / fiber composite, where the density of the polymer / fiber composite is increased by a factor of ≥ 3 compared to the corresponding fiber web, wherein the aqueous dispersion of the polymer P is obtained by free-radically initiated emulsion polymerization of a monomer composition composed of 5% to 30% by weight of one or more monomers M1 selected from esters of acrylic and / or methacrylic acid with alkanols having 2 to 8 carbon atoms, 70% to 95% by weight of styrene and / or methyl methacrylate (M2), and 0% to 10% by weight of at least one further ethylenically unsaturated compound (M3) which is copolymerizable with monomers M1 and M2, based in each case on the total amount of the monomers M, in an aqueous medium in the presence of a polymer A or a polymer mixture A, where polymer A or polymer mixture A is formed from 40% to 70% by weight of acrylic acid (monomer A1), 30% to 60% by weight of maleic acid and / or maleic anhydride (monomer A2), 0% to 5% by weight of at least one further ethylenically unsaturated compound which is copolymerizable with monomers A1 and A2 (monomer A3), and where the total amounts of monomers A add up to 100% by weight, with the proviso that neither polymer A nor polymer mixture A is formed from an ester selected from the esters of ethylenically unsaturated monocarboxylic acids with amines having at least two hydroxyl groups, the monoesters and the diesters of ethylenically unsaturated dicarboxylic acids with amines having at least two hydroxyl groups.

2. The process according to claim 1, wherein the fibrous substrate used is a natural fiber.

3. The process according to claim 1 or 2, wherein polymer A has a weight-average molecular weight Mw of ≥ 1000 and ≤ 20 000 g / mol, determined by gel permeation chromatography using a polyacrylic acid sodium salt as standard to DIN EN ISO 13885-3.

4. The process according to any of claims 1 to 3, wherein the aqueous dispersion of polymer P is obtained by free-radically initiated emulsion polymerization in an aqueous medium in the presence of a polymer mixture A, where the polymer mixture A comprises 10% to 30% by weight of a polymer A1 having a weight-average molecular weight of ≥ 7000 and ≤ 20 000 g / mol and 70% to 90% by weight of a polymer A2 having a weight-average molecular weight of ≥ 1000 and ≤ 5000 g / mol, based on the total amount of polymer mixture A.

5. The process according to any of claims 1 to 4, wherein the ratio of the amount of polymer A to the total amount of monomers M is in the range from 10:90 to 50:50, and that of polymer mixture A to the total amount of monomers M is in the range from 10:90 to 50:50.

6. The process according to any of claims 1 to 5, wherein the glass transition temperature of polymer P is ≥ 60°C and ≤ 150°C.

7. The process according to any of claims 1 to 6, wherein the aqueous dispersion of polymer P is obtainable by free-radically initiated emulsion polymerization of a monomer composition composed of 5% to 30% by weight of one or more monomers M1 selected from esters of acrylic and / or methacrylic acid with alkanols having 2 to 8 carbon atoms, 70% to 94.9% by weight of styrene and / or methyl methacrylate (M2), 0.1% to 10% by weight of at least one further ethylenically unsaturated compound (M3) which is copolymerizable with monomers M1 and M2, of which 0.1% to 5.0% by weight, based on total monomers M, is glycidyl acrylate and / or glycidyl methacrylate, based in each case on the total amount of the monomers M.

8. The process according to any of claims 1 to 7, wherein the aqueous dispersion of polymer P is obtainable by free-radically initiated emulsion polymerization of a monomer composition composed of 5% to 20% by weight of ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, hexyl acrylate and / or 2-ethylhexyl acrylate, 70% to 94.9% by weight ofstyrene and / or methyl methacrylate, 0.1% to 5.0% by weight ofglycidyl acrylate and / or glycidyl methacrylate, 0% to 5.0% by weight of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and / or 3-hydroxypropyl acrylate and / or 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and / or 3-hydroxypropyl methacrylate, 0% to 2.0% by weight of 1,4-butylene glycol diacrylate, 1,4-butylene glycol dimethacrylate, 1,2-, 1,3- and / or 1,4-divinylbenzene, allyl acrylate and / or allyl methacrylate, based in each case on the total amount of the monomers M.

9. The process according to any of claims 1 to 8, wherein the dispersion of polymer P comprises ≤ 3% by weight of an amine having at least two hydroxyl groups based on the sum total of polymer A and total monomers M or based on the sum total of polymer mixture A and total monomers M.

10. The process according to any of claims 1 to 9, wherein the thermoformable polymer / fiber composite obtained has a basis weight of ≥ 1000 and ≤ 30 000 g / m2.

11. The process according to any of claims 1 to 10, wherein the thermoformable polymer / fiber composite obtained is two-dimensional.

12. A thermoformable polymer / fiber composite obtainable by a process according to any of claims 1 to 11.

13. The use of the thermoformable polymer / fiber composite according to claim 12 for production of a polymer / fiber molding which differs in shape from the polymer / fiber composite used.

14. A process for producing a polymer / fiber molding, which comprises heating the thermoformable polymer / fiber composite according to claim 12 up to a temperature ≥ the glass transition temperature Tg of polymer P and converting it to the desired shape of the polymer / fiber molding at a temperature ≥ the glass transition temperature Tg of polymer P and then cooling the resultant polymer / fiber molding down to a temperature < the glass transition temperature Tg of polymer P while maintaining its shape.

15. A polymer / fiber molding obtainable by a process according to claim 14.

16. The use of a polymer / fiber molding according to claim 15 as a furniture molding, wall decor part or interior component in vehicle construction.

17. A process for producing an aqueous dispersion of polymer P according to any of claims 1 and 3 to 8 by free-radically initiated emulsion polymerization of a monomer composition composed of 5% to 30% by weight of one or more monomers M1 selected from esters of acrylic and / or methacrylic acid with alkanols having 2 to 8 carbon atoms, 70% to 95% by weight of styrene and / or methyl methacrylate (M2), and 0% to 10% by weight of at least one further ethylenically unsaturated compound (M3) which is copolymerizable with monomers M1 and M2, based in each case on the total amount of the monomers M, in an aqueous medium in the presence of a polymer A or a polymer mixture A, where polymer A or polymer mixture A is formed from 40% to 70% by weight of acrylic acid (monomer A1), 30% to 60% by weight of maleic acid and / or maleic anhydride (monomer A2), 0% to 5% by weight of at least one further ethylenically unsaturated compound which is copolymerizable with monomers A1 and A2 (monomer A3), and where the total amounts of monomers A add up to 100% by weight, with the proviso that neither polymer A nor polymer mixture A is formed from an ester selected from the esters of ethylenically unsaturated monocarboxylic acids with amines having at least two hydroxyl groups, the monoesters and the diesters of ethylenically unsaturated dicarboxylic acids with amines having at least two hydroxyl groups.

18. An aqueous dispersion of polymer P obtainable by a process according to claim 17.