TEXTILE SHEET MATERIAL
A process for producing textile fabrics by applying one or more binder compositions to fibers is provided. The binder compositions include one or more polysaccharides and one or more polymers of vinyl acetate. The polymers of vinyl acetate are based on vinyl acetate to an extent of 50% to 90% by weight based on the total weight of the polymers of vinyl acetate.
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The invention relates to processes for producing textile fabrics, to the textile fabrics obtainable in this way, and to binder compositions for the production of textile fabrics.
Textile fabrics are based on fiber materials, which may be wovens, knitted goods or nonwovens and consolidated with binders, examples being nonwoven webs or felts. Nonwovens are usually produced by airlay, wetlay or spunlay processes. Polymers of ethylenically unsaturated monomers are often used as binders to consolidate textile fabrics and are applied to the fiber material for example in the form of aqueous dispersions, followed by subsequent drying.
For ecological reasons there is nowadays a desire to at least partially replace petrochemical polymers with natural, renewable raw materials. A decline in performance properties should as far as possible be avoided here. A problem arising here is that the chemical structures of renewable raw materials are very different to those of petrochemical polymers, which means that the replacement of petrochemical polymers in established formulations or processes with natural, renewable biopolymers often gives rise to incompatibilities and the separation of different substances and a consequent inability to obtain stable mixtures, this being reflected in unacceptable properties in use products. What makes this even more acute is that biopolymers are present not so much as a single type, but also as mixtures of different substances, or can have broad molecular weight distributions, which in turn can vary according to the origin of the biopolymers.
Moreover, textile fabrics having biopolymers as binders often do not have the requisite mechanical strength or resistance, for example a wet tensile strength or solvent resistance that is too low, especially in the case of short fibers.
Against this background, the object was that of producing textile fabrics using binder compositions that comprise natural, renewable raw materials and result in textile fabrics having a performance property profile close to that of textile fabrics conventionally produced with exclusively petrochemical polymers as binders. The binder compositions should permit application by established methods and be compatible with otherwise conventional formulation constituents, affording stable mixtures with no tendency to separate. In addition, textile fabrics should also be provided that are as far as possible biodegradable. The textile fabrics should preferably also have advantageous mechanical strengths.
Biopolymers are used for example in technologies that are far removed from textile fabrics. For instance, WO 9222606A1 describes hot-melt adhesives produced from meltable polysaccharides and ethylene-vinyl acetate copolymers and WO9742271A1 describes adhesives produced from synthetic polymers in combination with dextrin (derivatives). WO2008003043A2 teaches matrices produced from degradable and non-degradable polymers for the incorporation of therapeutically active compounds. WO2010/133560 or also WO2004/085533 disclose thermoplastically processable mixtures based on synthetic polymers and flour or starch for the extrusion of shaped bodies. WO2019/043134 relates to plastic products based on polyesters in general, such as lactic acid or terephthalic acid, and for example polysaccharides.
The invention provides processes for producing textile fabrics by applying one or more binder compositions to fibers, characterized in that the binder compositions comprise one or more polysaccharides and one or more polymers of vinyl esters.
The invention further provides textile fabrics obtainable by the process according to the invention.
The invention further provides binder compositions for textile fabrics comprising one or more polysaccharides and one or more polymers based on one or more vinyl esters and one or more ethylenically unsaturated monomers bearing carboxyl, anhydride, silane, isocyanate, amide, hydroxyl, epoxy or NH groups (crosslinking monomers). With such binder compositions it is possible in particular to further improve the mechanical strength, such as wet tensile strength, of the textile fabrics.
The polymers of vinyl esters (vinyl ester polymers) are based preferably on vinyl esters of unbranched or branched alkyl carboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate, and vinyl esters of α-branched monocarboxylic acids having 5 to 15 carbon atoms, for example VeoVa9R or VeoVa10R (trade names of Shell). Preference is given to vinyl acetate.
Preferred vinyl ester polymers are based on vinyl esters to an extent of 50% to 100% by weight, more preferably 60% to 94% by weight, and most preferably 70% to 90% by weight, based on the total weight of the vinyl ester polymers.
The vinyl ester polymers are optionally additionally based on one or more monomers selected from the group comprising acrylic esters or methacrylic esters of branched or unbranched alcohols having 1 to 15 carbon atoms, dienes, olefins, vinyl aromatics, and vinyl halides. Preference is given here to olefins.
The vinyl ester polymers are preferably based on such additional monomers to an extent of 1% to 45% by weight, more preferably 5% to 30% by weight, and most preferably 15% to 25% by weight, based on the total weight of the vinyl ester polymers.
Suitable monomers from the group of esters of acrylic acid or methacrylic acid are esters of unbranched or branched alcohols having 1 to 15 carbon atoms. Preferred methacrylic esters or acrylic 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, and norbornyl acrylate. Particular preference is given to methyl acrylate, methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and norbornyl acrylate.
Examples of suitable dienes are 1,3-butadiene and isoprene. Examples of copolymerizable olefins are ethene and propene. Examples of vinyl aromatics that can be copolymerized are styrene and vinyl toluene. Preference as the vinyl halide is given to vinyl chloride.
The vinyl ester polymers are preferably additionally based on one or more ethylenically unsaturated monomers additionally bearing carboxyl, anhydride, silane, isocyanate, amide, hydroxyl, epoxy or NH groups (crosslinking monomers). Preference is given here to crosslinking monomers bearing NH groups. Vinyl ester polymers containing crosslinking monomer units result in textile fabrics having higher strengths and resistances, for example dry strength and especially wet strength and solvent resistance.
Examples of carboxyl-functional comonomers are ethylenically unsaturated mono- and dicarboxylic acids having 2 to 10 carbon atoms, preferably acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, and maleic acid. Examples of anhydride-functional comonomers are maleic anhydride or ethylenically unsaturated succinic anhydride derivatives, such as alkenyl succinic anhydrides, especially ones having 2 to 25 carbon atoms in the alkenyl radical. Examples of silicon-functional comonomers are acryloyloxypropyltrialkoxy- and methacryloyloxypropyltrialkoxysilanes, vinyltrialkoxysilanes, and vinylmethyldialkoxysilanes, wherein it is possible for the alkoxy groups to be present for example in the form of ethoxy and ethoxypropylene glycol ether radicals. Examples of hydroxy-functional comonomers are hydroxyalkyl acrylates and hydroxyalkyl methacrylates having a C1 to C8 alkyl radical, preferably hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, and hydroxybutyl acrylate and methacrylate. Examples of epoxy functional comonomers are glycidyl acrylate and glycidyl methacrylate. Examples of NH-functional comonomers are acrylamide, methacrylamide, N-alkylol-functional comonomers having a C1 to C4 alkylol radical, preferably N-methylol radical, for example N-methylolacrylamide (NMA), N-methylolmethacrylamide, N-methylolallyl carbamate, C1 to C4 alkyl ethers of N-methylolacrylamide, of N-methylolmethacrylamide, and of N-methylolallyl carbamate, for example the isobutoxy ethers thereof, and C1 to C4 alkyl esters of N-methylolacrylamide, of N-methylolmethacrylamide, and of N-methylolallyl carbamate.
Particularly preferred crosslinking monomers are N-methylol-functional monomers, most preferred are N-methylolacrylamide, N-methylolmethacrylamide, N-methylolallyl carbamate, and C1 to C4 alkyl ethers of N-methylolacrylamide such as the isobutoxy ether.
The vinyl ester polymers are preferably based on crosslinking monomers to an extent of 0% to 10% by weight, more preferably 0.1% to 5% by weight, and most preferably 0.5% to 2% by weight, based on the total weight of the vinyl ester polymers.
Preference is given to the vinyl ester polymers mentioned below, into which the crosslinking monomers mentioned above can optionally also be incorporated by polymerization, preferably in the amounts mentioned above: vinyl acetate polymers; vinyl ester-ethylene copolymers such as vinyl acetate-ethylene copolymers; vinyl acetate copolymers with one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of an alpha-branched carboxylic acid having 5 to 15 carbon atoms, especially vinyl versatates (VeoVa9R, VeoVa1OR), which may optionally also contain ethylene; vinyl ester-ethylene-vinyl chloride copolymers, wherein the vinyl esters present are preferably vinyl acetate and/or vinyl propionate and/or one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of an alpha-branched carboxylic acid having 5 to 15 carbon atoms, especially vinyl versatates (VeoVa9R, VeoVa1OR); vinyl ester-acrylic ester copolymers, especially with vinyl acetate and butyl acrylate and/or 2-ethylhexyl acrylate, which may optionally also contain ethylene; vinyl ester-acrylic ester copolymers with vinyl acetate and/or vinyl laurate and/or vinyl versatates and acrylic esters, especially butyl acrylate or 2-ethylhexyl acrylate, which may optionally also contain ethylene.
Particular preference is given to vinyl acetate polymers, vinyl acetate-ethylene copolymers, vinyl acetate-ethylene-vinyl chloride copolymers, vinyl ester-acrylic ester copolymers, especially with vinyl acetate and butyl acrylate and/or 2-ethylhexyl acrylate, in which N-methylol-functional monomers may optionally also be incorporated by polymerization, preferably in the amounts mentioned above.
Most preferred are N-methylol-functional vinyl ester polymers such as vinyl acetate-N-methylolacrylamide copolymers and vinyl acetate-ethylene-N-methylolacrylamide copolymers and combinations thereof.
The monomers and the proportions by weight of the comonomers are selected so as to result in polymers having a glass transition temperature Tg of −50° C. to +120° C., preferably −35° C. to +45° C.
The glass transition temperature Tg of the polymers can be determined in a known manner by differential scanning calorimetry (DSC). The Tg can also be predicted approximately by means of the Fox equation. According to Fox T.G., Bull. Am. Physics Soc. 1, 3, page 123 (1956): 1/Tg=x1/Tg1+x2/Tg2+ . . . +xn/Tgn, where xn is the mass fraction (% by weight/100) of the monomer n, and Tgn the glass transition temperature in kelvins of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975).
The binder compositions contain preferably 1% to 90% by weight, more preferably 10% to 85% by weight, more preferably still 15% to 80% by weight, particularly preferably 20% to 75% by weight, and most preferably 30% to 70% by weight, of vinyl ester polymers, based on the dry weight of the binder compositions.
Preference is given to vinyl ester polymers stabilized with protective colloids, more preference to vinyl ester polymers stabilized with emulsifiers, and most preference to vinyl ester polymers stabilized with nonionic emulsifiers or combinations thereof. The vinyl ester polymers are preferably not stabilized with protective colloids. With these measures, the object of the invention can be achieved even more readily.
Examples of protective colloids are polyvinyl alcohols, polyvinyl acetals, polyvinylpyrrolidones, copolymers of (meth)acrylates with carboxyl-functional comonomer units, poly(meth)acrylamide, polyvinylsulfonic acids and copolymers thereof, melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, and styrene-maleic acid and vinyl ether-maleic acid copolymers. Preferred protective colloids are partially hydrolyzed polyvinyl alcohols preferably having a degree of hydrolysis of 80 to 95 mol %, especially 85 to 92 mol %, and preferably having a Hoppler viscosity in a 4% aqueous solution of 1 to 30 mPa·s, especially 3 to 15 m·Pas (Hoppler method at 20° C., DIN 53015). The protective colloids mentioned are obtainable by methods known to those skilled in the art.
The vinyl ester polymers are generally not stabilized with polysaccharides. The polysaccharides present in the binder compositions generally do not function as protective colloids. The polysaccharides and the vinyl ester polymers, more particularly the vinyl ester polymers stabilized with protective colloids and/or emulsifiers, are preferably present alongside one another.
The proportion of protective colloid is preferably 0% to 30% by weight, more preferably 0.5% to 25% by weight, and most preferably 1% to 20% by weight, based on the total weight of the vinyl ester polymers.
Anionic, cationic or nonionic emulsifiers or combinations thereof may be used. Preference is given to anionic emulsifiers and particular preference to nonionic emulsifiers.
Examples of anionic emulsifiers are alkyl sulfates, sulfonates or carboxylates having a chain length of 8 to 18 carbon atoms, alkyl or alkylaryl ether sulfates, sulfonates or carboxylates having 8 to 18 carbon atoms in the hydrophobic radical and up to 40 ethylene oxide or propylene oxide units, alkyl or alkylaryl sulfonates having 8 to 18 carbon atoms, esters and hemiesters of sulfosuccinic acid with monohydric alcohols or alkylphenols, or phosphates, ether phosphates, phosphonates, and ether phosphonates and combinations thereof.
Examples of nonionic emulsifiers are alkyl polyglycol ethers or alkylaryl polyglycol ethers having 8 to 40 ethylene oxide units or ethylene oxide/propylene oxide block copolymers having 2 to 40 EO or PO units or EO-PO copolymers in general, and also alkyl polyglycosides having 1 to 20 carbon atoms and ether alkyl polyglycosides having 2 to 40 EO or PO units or thereof.
The proportion of emulsifier is preferably 0% to 15% by weight, more preferably 0.1% to 5% by weight, and most preferably 0.5% to 3% by weight, based on the total weight of the vinyl ester polymers.
The vinyl ester polymers can be prepared by known free-radical-initiated polymerization processes, for example by aqueous suspension polymerization or preferably aqueous emulsion polymerization, as described for example in WO2015/067621.
The vinyl ester polymers are preferably present in the form of aqueous dispersions having a solids content of preferably 10% to 70% by weight, more preferably 40% to 60% by weight.
The Brookfield viscosity of the aqueous dispersions of the vinyl ester polymers is preferably 50 to 10 000 m·Pas, more preferably 100 to 2000 m·Pas (determined using a Brookfield viscometer at 23° C. and 20 rpm at a solids content in the dispersions of 49% to 51% by weight).
Alternatively, the vinyl ester polymers may also be in the form of water-redispersible powders (polymer powders). Such polymer powders can be obtained for example by spray-drying of aqueous polymer dispersions. Additives such as flame retardants, plasticizers, fillers, and complexing agents may optionally be added during drying. Dispersing such polymer powders results again in vinyl ester polymers in the form of aqueous dispersions.
Examples of polysaccharides include starch, glycogen, cellulose, cellulose derivatives such as chitosan and chitin, hyaluronic acid, glycosaminoglycans, alginates, galactans, cane sugar, maltodextrin or products obtained by enzymatic or chemical cleavage or chemical modification of the abovementioned polysaccharides, or polysaccharides based on the monomers glucose, sucrose, fructose, galactose, lactose, maltose, mannose or on the respective tautomeric structures or combinations thereof. The polysaccharides may additionally also comprise modifications with polymers based on protein structures or amino acids, such as glycoproteins or derivatives thereof. Preference is given to cellulose, cellulose derivatives, starch and short-chain degradation products thereof, such as dextrins and maltodextrins. Chemical modifications include esterifications or etherifications, such as carboxymethylation, oxidation reactions or also nonionic, anionic or cationic modifications. Examples thereof are carboxymethyl, methyl, hydroxyethyl or hydroxypropyl cellulose or starch, starch ethers or starch phosphate esters or oxidation products thereof. Typical sources of polysaccharides are cereals, tubers, roots, legumes, fruit starch, hybrid starch, maize, peas, potatoes, sweet potatoes, wheat, barley, rice, sorghum or tapioca. Preference is given to polysaccharides soluble in cold water. The polysaccharides have molecular weights of preferably 300 to 2 700 000 g/mol. The polysaccharides are preferably based on 2 to 15 000 glucose molecules. With the preferred polysaccharides, the object of the invention can be achieved even more readily.
The binder compositions contain preferably 5% to 95% by weight, more preferably 15% to 90% by weight, more preferably still 20% to 80% by weight, particularly preferably 25% to 70% by weight, and most preferably 30% to 60% by weight, of polysaccharides, based on the dry weight of the binder compositions.
The binder compositions preferably comprise one or more crosslinkers, such as chemical crosslinkers, electrostatic crosslinkers or van der Weals crosslinkers and combinations thereof.
Examples of chemical crosslinkers are alkyl ureas, such as methyl ureas and derivatives thereof, especially dimethylolethylene urea and derivatives thereof, for example Arkofix® NZF (trade name of Archroma); melamine crosslinkers and derivatives thereof, such as Madurit® MW 125 (trade name of Ineos) or Knittex® CHN (trade name of Huntsman); aliphatic polycarboxylic acids such as butane-1,2,3,4-tetracarboxylic acid, polyisocyanates; citric acid, protected polyisocyanates, epoxides, halogenated hydrocarbons such as brominated or chlorinated hydrocarbons, especially chloroform or trichloromethane, or alkoxylated silanes or combinations thereof.
Electrostatic crosslinkers generally contain ionic groups or groups forming hydrogen bonds, such as C—N, C—O, H—N, H—O and H—S groups or ionic substances having cationic or anionic functional groups.
Examples of electrostatic crosslinkers having groups that form hydrogen bonds are polyacrylamides (PAM) and derivatives thereof. Examples of substances having cationic functional groups are quaternary ammonium compounds or protonatable amine compounds, such as monoammonium or polyammonium compounds, for example polyamidoamine-epichlorohydrin resins (PAE, trade name Kymene® from Solenis); or partially or fully protonated chitosans or reaction products thereof, for example with epichlorohydrins, and combinations thereof. Examples of substances having anionic functional groups are mono- or polycarboxylates, such as carboxymethylcellulose (CMC), sulfonates, sulfinates or sulfides, and also copolymers of polyacrylamides having carboxy groups or combinations thereof.
Examples of van der Weals crosslinkers are high-molecular-weight nanocomposites such as nanocellulose or synthetic nanoplastics.
The binder compositions contain preferably 0% to 40% by weight, more preferably 0.1% to 35% by weight, particularly preferably 1% to 25% by weight, and most preferably 2% to 15% by weight, of crosslinkers, based on the dry weight of the mixtures.
The binder compositions may additionally comprise one or more additives, such as emulsifiers, protective colloids such as polyvinyl alcohols, polyurethanes, polyacrylates, and derivatives thereof, catalysts, wetting agents or dispersants, dyes, matting agents, fillers such as inorganic salts (for example CaCO3, NaCl, TiO2, kaolin, silicic acids and derivatives thereof, and combinations thereof), optical brighteners based on for example stilbene compounds, free-radical scavengers or color stabilizers, antioxidants such as butylated hydroxytoluene, hydroxybenzophenone, salicylic esters, complexing agents such as water softeners based on ethylene tetraacetate salts, also superabsorbent polymers, handling components such as plasticizers, hydrophobizing agents such as fluorocarbons, silicones, natural and synthetic waxes (for example paraffins and polyethylenes), resins, flame retardant additives, antistatic additives, biocides, rheology additives, foam regulators or retention additives.
Preferred additives are emulsifiers and especially catalysts.
The binder compositions contain preferably 0% to 40% by weight, more preferably to 30% by weight, and most preferably 1% to 20% by weight, of additives, based on the dry weight of the binder compositions.
Examples of emulsifiers are fatty alcohol ethoxylates having a low degree of ethoxylation, especially 2 to 5 ethoxy units, diisotridecyl sulfosuccinate or salts thereof, especially sodium salts, or combinations thereof. The binder compositions contain preferably 0% to 15% by weight, more preferably 0.1% to 5% by weight, and most preferably 0.5% to 3% by weight, of emulsifiers, based on the dry weight of the binder compositions. Emulsifiers can be used to influence for example secondary properties such as hydrophilicity, soiling behavior, wettability or yellowing of the textile fabrics.
Preference is given to acidic catalysts such as ammonium chloride, carboxylic acids such as citric acid, acetic acid, malic acid, formic acid, tartaric acid, oxalic acid, especially hydroxy- or dicarboxylic acids, sulfuric acid, phosphoric acid or Brønsted acids in general. In the case of Brønsted acids, a pH of preferably 0 to 5 and more preferably 2 to 4 is established. Acid catalysts are preferably added in amounts of 0% to 3% by weight, preferably 0.1% to 2% by weight, based on the dry weight of the binder compositions.
The fibers are generally based on natural or synthetic, especially organic, materials. Examples of synthetic fibers are viscose, polyester, polyamide, polypropylene or polyethylene fibers or blends thereof or co-extrudates thereof, which are for example also referred to as “BiCo fibers”. Examples of natural fibers are wood, pulp, leather, fur, wool, cotton, jute, flax, hemp, coir, ramie, sisal and cellulose fibers. Preference is given to cellulose fibers such as viscose, modal, lyocell, acetate, triacetate, cupro, rayon, and cellulose fibers from pulp. Particular preference is given to fiber blends that preferably comprise a plurality of the abovementioned fibers. The fibers are preferably not based on inorganic materials. The fibers are thus preferably no ceramic fibers or mineral fibers and especially no glass fibers. Such fibers can be produced by conventional means and are commercially available.
The fibers may be of any length, for example lengths from 1 mm to infinite length, preferably 5 mm to 100 mm, more preferably 7 mm to 75 mm, and most preferably mm to 60 mm. The fibers have diameters of preferably 0.1 μm to 1 mm, more preferably 0.5 μm to 100 μm, and most preferably 1 μm to 50 μm.
The fibers can be used loosely or in the form of bundles or woven textiles, yarns or preferably in the form of nonwovens, such as nonwoven webs and felts, non-crimp fabrics or knitted fabrics, or else wovens or carpets. The nonwovens may optionally be thermally or mechanically preconsolidated, for example needled or hydroentangled.
Binder compositions may be present for example in solid form, preferably in liquid form, especially in aqueous form. Binder compositions in solid form may be converted into aqueous form by adding water.
Binder compositions in aqueous form have a solids content of preferably 1% to 80% by weight, more preferably 10% to 70% by weight, and most preferably 20% to 60% by weight.
For the production of the binder compositions, the vinyl ester polymers, polysaccharides, any crosslinkers, and any additives are mixed together. For example, polysaccharides in solid or aqueous form may be mixed with vinyl ester polymers in the form of water-redispersible powders and water optionally added at the same time or at a later point in time. The polysaccharides are preferably introduced in aqueous form and the vinyl ester polymers in the form of aqueous dispersions. The polysaccharides are preferably stirred into water under high shear. Polysaccharides soluble in hot water are preferably stirred into hot water or diluted with hot water after premelting. Polysaccharides soluble in cold water are preferably stirred into water at room temperature, for example 20 to 30° C., while stirring for example with a paddle stirrer, preferably until optical homogeneity. This is preferably followed by the addition of vinyl ester polymers in the form of aqueous dispersions.
For the production of the textile fabrics, the fibers can for example be mixed with the binder compositions and the resulting mixture laid out by customary nonwoven technology methods, for example using devices for airlaying, wetlaying, direct spinning or carding, and then optionally consolidated.
Alternatively, the fibers can also be spread out flat and the binder compositions optionally applied before or after before consolidation. Such approaches are common too. The fibers can be laid out for example by means of a device for airlaying, wetlaying, direct spinning or carding. They can optionally also be mechanically consolidated prior to application of the binder composition, for example by crosslaying, needling or hydroentanglement. The binder compositions can be applied for example evenly, in spots, or in a pattern, over the entire area or partial areas of the fibers. The application can take place for example by forced application, such as spraying, roll-dipping (padding), coating, brushing, dipping or by foam application, or by non-forced application, such as the exhaust method, or by combined methods, for example the overflow jet method.
The product thus obtained can then undergo drying, consolidation, fixing or binding treatments, for example by applying elevated temperatures and/or pressure, for example at 120 to 220° C., preferably for 20 seconds to 5 minutes. Air drying, convection drying, airflow drying or infrared (IR) drying can also be employed.
The binder compositions are suitable also for the production of laminates, wherein two fiber layers are bonded together or a fiber layer is bonded to another substrate. The procedure can be such that a fiber layer is laid out, with the binder composition mixed beforehand or applied after said layer has been laid out, and a further fiber layer laid on top, for example by airlaying. Instead of the second fiber layer, a different substrate, for example a plastic film, can also be laid on top. Bonding then takes place through the application of temperature and optionally pressure. With this procedure it is possible to obtain for example insulating materials, made for example of recycled cotton, which are for example durably laminated with a nonwoven fiber web as a cover web.
For the production of the textile fabrics, the aqueous binder composition is used in an amount of preferably 1% to 50% by weight, more preferably 5% to 30% by weight, and most preferably 10% to 25% by weight, in each case based on the total weight of the fibers (dry/dry). Vinyl ester polymers are used in an amount of preferably 1% to 50% by weight, more preferably 5% to 30% by weight, and most preferably 10% to 25% by weight, based on the total weight of the fibers (dry/dry). The proportion of fibers is preferably 40% to 99% by weight, more preferably 50% to 90% by weight, and most preferably 60% to 80% by weight, in each case based on the total weight of the textile fabric.
The textile fabrics produced according to the invention are preferably nonwovens, especially tissues, felts, waddings or coarse-meshed, loose wovens, knitted fabrics or warp-knitted fabrics. The textile fabrics can be used for example in the automotive sector, for household products such as tablecloths, sanitary articles such as toilet paper, in the clothing industry, and for medical textiles or geotextiles.
The binder compositions are also suitable for the production of voluminous nonwovens or waddings that are used for example as semifinished products for the production of moldings from fiber materials or as padding, insulating, and filter waddings. For this purpose, the binder compositions can be applied to the fibers and consolidated by increasing the temperature, preferably in a mold.
The binder compositions according to the invention, which in addition to polysaccharides comprise vinyl ester polymers, are surprisingly stable and have no tendency to separate, not even in the production facilities and process conditions during the production of textile fabrics. The binder compositions can be applied as binders for textile fabrics by established methods.
In addition, the textile fabrics produced according to the invention have the desired performance properties, such as mechanical properties, and fix the fibers durably, which represents a particular challenge when using binders having biopolymer components. With the present invention it is possible using polysaccharides in binders to obtain textile fabrics that have advantageous strengths and resistances, such as dry strength or even also wet strength, or improved solvent resistance, and that have the desired resistance to mechanical stress without the integrity and elasticity of the textile fabric being significantly affected.
Alongside the goal of increasing the provision of textile fabrics based on renewable raw materials, the biodegradability of textile fabrics is also an important ecological criterion. This criterion too can be advantageously achieved with the textile fabrics produced according to the invention.
The examples that follow serve to further elucidate the invention:
Preparation of the Binder Compositions:
The polysaccharides (hereinafter abbreviated as “PSC”) were stirred into water under high shear.
For this, polysaccharides soluble in hot water were stirred into hot water under high shear or diluted with hot water by premelting.
Polysaccharides soluble in cold water were mixed with water at room temperature with a paddle stirrer at 400-1000 rpm for 15 to 30 minutes until optically homogeneous.
Vinyl ester polymers (abbreviated as “VAE”) were then added in the form of an aqueous dispersion, and stirring with a paddle stirrer was continued for 5 minutes.
Testing the Compatibility and Storage Stability of the Binder Compositions:
The binder compositions were based in each case on 50 wt % (dry) of the polysaccharides (PSC) and the vinyl ester polymer dispersions (VAE) stabilized with aqueous emulsifiers or polyvinyl alcohol shown in Table 1a and after their preparation were stored at room temperature for one month and their storage stability and separation investigated after the periods specified in Table 1 b. The results are summarized in Table 1 b.
Surprisingly, the binder compositions with the emulsifier-stabilized vinyl ester polymer dispersions of examples 1 and 2 were more stable than the analogous compositions of example 3 stabilized with the protective colloid polyvinyl alcohol.
The binder compositions obtained with the nonionic emulsifier were here significantly more storage-stable than those with the anionic emulsifier, as shown by examples 1 and 2.
Determination of Biodegradability:
To test the biodegradability, binder systems are usually applied to biodegradable reference materials.
For this, 25 wt % (solid/solid) of the binder compositions shown in Table 2 was applied to cellulose powder and investigated for aerobic biodegradability in accordance with ISO 14855-1. The test results are summarized in Table 2.
Compared to the pure VAE binder of comparative example 4, the binder compositions of examples 5 and 6 show significantly higher degradability and thus meet the requirement for biodegradability of >90%.
Determination of the wet and dry strengths of nonwovens:
A thermally prebonded nonwoven airlaid web (75 g/m 2; 88% fluff pulp and 12% PP/PE bicomponent fibers; 0.85 mm thickness) was sprayed homogeneously on both sides with the dispersion of the binder composition of the respective example or comparative example diluted with water to a solids content of 20%, using the airless process (Unijet 8001 E slit nozzles; 5 bar) to apply a sprayable liquor using a semi-automatic spraying assembly, and then dried in a laboratory through-air dryer (Mathis LTF; Mathis, Switzerland) at 160° C. for 3 min (application rate: 20 wt % of binder composition based on the dry weight of binder composition and web).
For each breaking strength test, 10 web strips (20 cm clamped length; 5 cm clamped length) were produced in the transverse direction to the machine direction.
For measurement of the wet tensile strength, the strip samples were each stored in water for 1 min before the measurement.
The wet and dry strengths were determined in accordance with DIN EN 29073 (Part 3: Test method for nonwovens, 1992) and the measurement samples run by means of an ultimate tensile force measurement on a Zwick® 1445 testing machine (100 N load cell) with TestXpert® software version 11.02 (from Zwick Roell) with a clamped length of 100±1 mm, a clamped width of 15±1 mm, and a deformation velocity of 150 mm/min.
The formaldehyde content was determined according to ISO 14184-1.
The results of the testing are summarized in Tables 3 to 6.
Discussion of the Dry Strengths from Table 3:
The nonwovens of examples 8, 9, 11, and 12 come surprisingly close to the strengths of the nonwovens of comparative examples 7 and 10. This is surprising, because biopolymers otherwise usually result in a considerable deterioration in strength.
The nonwovens of examples 8, 9, 11, and 12 are agreeably soft despite the intrinsic hardening effect of the polysaccharides, and also exhibit good elasticity (elongation). In addition, the nonwovens of examples 8, 9, 11, and 12 have a lower formaldehyde content than the nonwovens of comparative examples 7 and 10, which has a beneficial effect on the toxicological profile of the nonwovens.
Discussion of Tables 4 to 6:
The results show that the wet strengths of the nonwovens comprising vinyl ester polymers VAE and polysaccharides PSC could be further improved by adding crosslinkers and catalysts.
The nonwovens obtained were agreeably soft despite the intrinsic hardening effect of the polysaccharides and even when crosslinkers were used, and they also exhibited good elasticity (elongation).
It was surprisingly possible to significantly reduce the formaldehyde content of the nonwovens, even when using a crosslinker, which has a beneficial effect on the toxicological profile of the nonwovens. Only in the case of crosslinker 2 are the formaldehyde values significantly higher, since this eliminates formaldehyde during crosslinking.
Claims
1-18. (canceled)
19. A process for producing textile fabrics by applying one or more binder compositions to fibers, wherein the binder compositions comprise one or more polysaccharides and one or more polymers of vinyl acetate,
- wherein the polymers of vinyl acetate are based on vinyl acetate to an extent of 50% to 90% by weight based on the total weight of the polymers of vinyl acetate.
20. The process for producing textile fabrics as claimed in claim 19, wherein polymers of vinyl acetate are additionally based on one or more monomers selected from the group comprising acrylic esters or methacrylic esters of branched or unbranched alcohols having 1 to 15 carbon atoms, dienes, olefins, vinyl aromatics, and vinyl halides.
21. The process for producing textile fabrics as claimed in claim 19, wherein polymers of vinyl acetate are additionally based on one or more ethylenically unsaturated monomers bearing carboxyl, anhydride, silane, isocyanate, amide, hydroxyl, epoxy or NH groups.
22. The process for producing textile fabrics as claimed in claim 21, wherein that monomers bearing carboxyl groups are selected from the group comprising acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, and maleic acid, that monomers bearing anhydride groups are selected from the group comprising maleic anhydride and ethylenically unsaturated succinic anhydride derivatives, that monomers bearing silane groups are selected from the group comprising acryloyloxypropyltrialkoxy- and methacryloyloxypropyltrialkoxysilanes, vinyltrialkoxysilanes, and vinylmethyldialkoxysilanes, wherein it is possible for the alkoxy groups to be present for example in the form of ethoxy and ethoxypropylene glycol ether radicals, that monomers bearing hydroxy groups are selected from the group comprising hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, and hydroxybutyl acrylate and methacrylate, that monomers bearing epoxy groups are selected from the group comprising glycidyl acrylate and glycidyl methacrylate, and that monomers bearing NH groups are selected from the group comprising acrylamide, methacrylamide, N-alkylol-functional comonomers having a C1 to C4 alkylol radical, C1 to C4 alkyl ethers of N-methylolacrylamide, of N-methylolmethacrylamide, and of N-methylolallyl carbamate, and C1 to C4 alkyl esters of N-methylolacrylamide, of N-methylolmethacrylamide, and of N-methylolallyl carbamate.
23. The process for producing textile fabrics as claimed in claim 19, characterized in that polymers of vinyl acetate are additionally based on one or more ethylenically unsaturated monomers bearing NH groups selected from the group comprising N-methylolacrylamide, N-methylolmethacrylamide, N-methylolallyl carbamate, and C1 to C4 alkyl ethers of N-methylolacrylamide.
24. The process for producing textile fabrics as claimed in claim 19, wherein polymers of vinyl acetate are stabilized with protective colloids.
25. The process for producing textile fabrics as claimed in claim 19, wherein polymers of vinyl acetate are stabilized with emulsifiers.
26. The process for producing textile fabrics as claimed in claim 19, wherein polymers of vinyl acetate are stabilized with nonionic emulsifiers.
27. The process for producing textile fabrics as claimed in claim 19, wherein one or more polysaccharides are selected from the group comprising starch, glycogen, cellulose, cellulose derivatives, chitosan, chitin, hyaluronic acid, glycosaminoglycans, alginates, galactans, cane sugar, maltodextrin or products obtained by enzymatic or chemical cleavage or chemical modification of the abovementioned polysaccharides, glycoproteins and derivatives thereof, and polysaccharides based on glucose, sucrose, fructose, galactose, lactose, maltose or mannose.
28. The process for producing textile fabrics as claimed in claim 19, wherein the binder compositions comprise one or more crosslinkers.
29. The process for producing textile fabrics as claimed in claim 28, wherein the binder compositions comprise one or more catalysts.
30. The process for producing textile fabrics as claimed in claim 19, wherein the fibers are natural, synthetic or other organic fibers, synthetic fibers being selected from the group comprising viscose, polyester, polyamide, polypropylene or polyethylene fibers or blends thereof or co-extrudates thereof, and natural fibers being selected from the group comprising wood, pulp, leather, fur, wool, cotton, jute, flax, hemp, coir, ramie, sisal and cellulose fibers.
31. A textile fabric obtainable by the process as claimed in claim 19.
32. The textile fabric as claimed in claim 31, wherein the textile fabric is biodegradable.
33. A binder composition for textile fabrics comprising one or more polysaccharides and one or more polymers of vinyl acetate that are based on acetate and one or more ethylenically unsaturated monomers bearing carboxyl, anhydride, silane, isocyanate, amide, hydroxyl, epoxy or NH groups,
- wherein the polymers of vinyl acetate are based on vinyl acetate to an extent of 50% to 90% by weight based on the total weight of the polymers of vinyl acetate.
34. The binder composition for textile fabrics as claimed in claim 33, wherein one or more crosslinkers are present.
35. The binder composition for textile fabrics as claimed in claim 34, wherein one or more catalysts are present.
Type: Application
Filed: Dec 8, 2020
Publication Date: Jan 25, 2024
Applicant: Wacker Chemie AG (Munich)
Inventors: Thomas LEHOTKAY (Mühldorf), Johanna HRGOVIC (Haiming)
Application Number: 18/265,526
