Bio-based binder compositions for nonwoven materials

Abstract

The present invention relates to a renewable, compostable, and / or biodegradable, environmentally friendly bio-based binder composition. The bio-based composition comprises chitosan, an acid, and a plasticizer. Treating nonwoven materials with the bio-based binder of the present invention can provide nonwoven materials with excellent mechanical properties. The binder composition of the present invention is easy to use in treating a wide variety of nonwoven materials and can be tailored to provide properties tailored to specific nonwoven materials and applications.

Description

[Technical Field]

[0001] The present invention relates to a renewable, compostable, and / or biodegradable, environmentally friendly bio-based binder composition comprising chitosan, an acid, and a linear polyol and / or a non-macrocyclic saccharide plasticizer. The present invention also relates to a method for treating nonwoven materials with the bio-based binder composition according to the present invention.

[0002] The compositions of the present invention are suitable as binders for various types of nonwoven materials. Treating various nonwoven materials with the binder compositions of the present invention provides nonwoven materials with excellent mechanical properties. Furthermore, the binder compositions of the present invention are easy to use in treating various types of nonwoven materials and can be tailored to provide properties tailored to specific nonwoven materials and applications. [Background technology]

[0003] A nonwoven material is a fabric-like material made from continuous or short fibers bonded together by chemical, mechanical, heat, or solvent treatment. A nonwoven fabric is also defined as a sheet or web structure bonded together by mechanically, thermally, or chemically intertwining fibers or filaments (and by perforating films). The term nonwoven fabric is used in the textile manufacturing industry to describe fabrics that are neither woven nor knitted, such as felt. Such fabrics are flat or tufted porous sheets made directly from discrete fibers, molten plastic, or plastic films.

[0004] Nonwoven materials can provide specific functions, such as absorbency, water repellency, flexibility, strength, flame retardancy, cushioning, thermal insulation, sound insulation, filtration, bacterial barrier properties, and sterility. These properties are often combined to create fabrics suitable for specific applications, while achieving a good balance between product lifespan and cost. Nonwoven materials can mimic the appearance, texture, and strength of woven fabrics and can be made as bulky as thick padding. Nonwoven materials can be combined with other materials to provide a range of products with diverse properties and are used alone or as components in clothing, home furnishings, healthcare, engineering, industrial, and consumer goods.

[0005] The creation of nonwoven materials begins with the arrangement of fibers into a web. There are various techniques for arranging the fibers, resulting in nonwoven materials with different properties suitable for different applications. Examples of nonwoven fabrics produced by various techniques include wet-laid nonwovens, air-laid nonwovens, carded nonwovens, spun-laid nonwovens, and air-laid nonwovens. Webs may have limited initial strength immediately after web formation and often must be strengthened by applying a binder to the web, thermally treating, or mechanically treating. Further versatility can be added to nonwoven materials through a variety of finishing processes.

[0006] The principle of producing wet-laid nonwovens is similar to that of papermaking. A dilute slurry of water and fibers is deposited onto a moving wire screen, where the water is drained and the fibers form a web. The web is further dewatered and dried by pressing between rollers. Typically during this process, a binder is used, either sprayed on or added to the paper slurry process, to increase the strength of the nonwoven material, for example, using a size press.

[0007] In the airlaid process, a continuous web of fibers is formed using air as a medium. Typically, the fibers are dispersed in an air stream and deposited, for example, on a moving wire. The resulting stack is then compressed, for example, by pressure or vacuum. However, unlike wetlaid nonwovens or papers, which can gain internal strength through hydrogen bonds formed in the wet process, these materials lack such internal strength and are therefore completely unbonded at this stage. Binders are typically added to airlaid nonwovens to achieve adhesion or other mechanical modifications, and the binder can be introduced at various stages of the manufacturing process depending on the type of binder used.

[0008] The production of carded nonwovens is a dry-laid nonwoven process, i.e., dry fibers are blended and then conveyed to a moving wire. They are then combed into a web by a carding machine, a rotating drum or series of drums covered with card wires (thin strips with teeth). The exact configuration of the card depends on the type and basis weight of the fibers being produced. Fiber bonding in carded nonwovens often involves hydroentangling (spunlacing) of the fibers with water jets using high pressure. Binders are also often added to carded nonwoven materials to improve strength and / or other properties.

[0009] Conventionally, both liquid binders, slurries, suspensions, foams, or powder binders are used in the production of nonwoven materials. The most common bonding technique involves adding a liquid binder to the nonwoven material, which is applied by, for example, impregnation, painting, or spraying.

[0010] The addition of binders to various nonwoven materials improves the strength of the material, but may also provide or improve other properties such as softness, flexibility, water repellency, or antimicrobial properties that are desired for a particular nonwoven material or application.

[0011] The properties desired for a particular nonwoven material or in a particular application of the nonwoven material can be further tailored by tailoring the addition, i.e., application level, of the binder composition.

[0012] One example of a desirable property is flexibility in airlaid nonwoven materials used to manufacture various hygiene products, such as disposable diapers, feminine hygiene products, industrial or consumer wipes, wet wipes, and napkins. Hygiene products are typically characterized by loft, softness, and high absorbency. For the soft airlaid nonwoven materials described above, elongation is a key requirement. If an airlaid nonwoven is too stiff, i.e., soft to the touch but not flexible, the airlaid nonwoven will be perceived as uncomfortable by the user. Elongation is also important because during the production of airlaid nonwoven materials and during processing into final products (e.g., converting airlaid nonwovens into napkins), the machines induce high tension in the material, requiring high elongation to prevent the material from breaking. Furthermore, airlaid nonwoven materials may tear during use if they lack sufficient strength or flexibility. Therefore, a combination of strength, softness, and elongation is crucial when developing airlaid nonwoven materials for the above applications. Treating an airlaid nonwoven material with a composition according to the present disclosure provides the airlaid nonwoven material with the required softness, strength, and elongation.

[0013] One desirable property of the binder composition itself is good adaptability of the binder to various nonwoven materials. Carded nonwoven materials are relatively dense, and applying a binder to carded nonwoven materials at satisfactory levels can be a difficult task. One alternative for applying binders to more difficult materials is to use foam impregnation. This requires that the binder be easily foamable with common foaming agents.

[0014] In an effort to reduce the use of synthetic, i.e., plastic, binders, attention has focused on bio-based polymers that can replace the synthetic polymers used in nonwoven fabrics. However, none of the alternatives to date have been able to produce nonwoven articles that have the excellent mechanical properties described above in a variety of nonwoven materials, while at the same time being adaptable to provide the properties required for a specific type of nonwoven material or application.

[0015] To date, attempts have been made to reduce or eliminate the use of synthetic binders in nonwoven fabrics, such as in WO2020068151. However, the articles disclosed in WO2020068151 still contain synthetic fibers and / or wet strength agents.

[0016] The use of chitosan as a binder component in nonwoven materials has been previously investigated, for example in WO 2012015863. However, as clearly stated in WO 2012015863, chitosan as the sole binder does not provide a good level of mechanical properties, such as tensile strength. Therefore, a synthetic component, namely vinyl acetate ethylene, has been provided to improve the above properties, as well as strength and elongation properties.

[0017] Biobased polyelectrolyte complexes (PECs) are also being investigated as environmentally friendly binder alternatives for materials such as fiber-based materials, textiles, woven fabrics, and nonwoven fabrics. PECs are association complexes formed between oppositely charged polycations and polyanions through electrostatic interactions between the oppositely charged polyions. Such binders are described, for example, in International Publication No. 2018038671. However, nonwoven fabrics treated with PEC binder compositions have elongation, i.e., elongation at break, of only about 3%, which does not work for applications requiring high flexibility, such as airlaid nonwoven fabrics. An elongation of about 5-9% is typically required for such applications.

[0018] Thus, there remains a need for bio-based binder compositions that are suitable for use with a variety of nonwoven materials and in a variety of applications, that provide the materials with excellent mechanical properties, and that also provide other properties required for the particular nonwoven material or application. Summary of the Invention [Problem to be solved by the invention]

[0019] It is an object of the present invention to provide a bio-based binder composition suitable as a binder for nonwoven materials.

[0020] It is an object of the present invention to provide a bio-based binder composition that is compatible with the processing of various types of nonwoven materials.

[0021] It is a further object of the present invention to provide a bio-based binder composition that provides excellent mechanical properties to various types of treated nonwoven materials.

[0022] It is a further object of the present invention to provide a bio-based binder composition that provides additional properties to treated nonwoven materials.

[0023] It is a further object of the present invention to provide a bio-based binder composition that imparts sufficiently high elongation to the treated nonwoven material.

[0024] It is a further object of the present invention to provide a bio-based binder composition that imparts sufficiently high elongation to the treated airlaid nonwoven material.

[0025] It is a further object of the present invention to provide an airlaid nonwoven material that exhibits strength and sufficiently good elongation, preferably at least 4% elongation.

[0026] It is a further object of the present invention to provide a bio-based binder composition that is easily applicable to a variety of nonwoven materials.

[0027] It is a further object of the present invention to provide a bio-based binder composition that provides superior strength to treated carded nonwoven materials.

[0028] It is a further object of the present invention to provide a bio-based binder composition that is renewable, compostable and / or biodegradable and environmentally friendly.

[0029] Any combination of the above objectives is also possible. [Means for solving the problem]

[0030] In a first general aspect, the present invention provides a bio-based aqueous binder composition for nonwoven materials, the binder composition comprising an acid, a plasticizer, and a cationic polyelectrolyte comprising chitosan; the chitosan has a deacetylation degree of 66 to 100%, and the binder composition contains 0.005 to 20% by weight of chitosan; the acid in the aqueous binder composition is a Brønsted acid and / or a Lewis acid, the Brønsted acid is selected from any organic acid and / or inorganic acid, the Lewis acid is selected from any cationic monovalent or polyvalent atom, and the aqueous binder composition preferably contains 0.01 to 30 wt. % of the acid; the aqueous binder composition comprises 0.5% to less than 15% by weight of a plasticizer, the plasticizer being a linear polyol selected from one or more of mannitol, maltitol, xylitol, and sorbitol, and / or a saccharide which is a non-macrocyclic saccharide selected from one or more of glucose, mannose, fructose, sucrose, sucralose, sucrose esters, hydrolyzed starch, or dextrin; the pH of the binder composition is less than 7; the cationic polyelectrolyte is not complexed with an anionic polyelectrolyte; Bio-based aqueous binder compositions for nonwoven materials.

[0031] The bio-based aqueous binder compositions of the present disclosure enable binders for nonwoven materials that are rich in renewable materials or made entirely from renewable materials. The binder compositions of the present disclosure have been found to provide excellent mechanical properties in wet-laid nonwoven materials, as well as air-laid and carded nonwoven materials.

[0032] According to IUPAC standards, "macrocyclic" means a cyclic polymer or a polymeric cyclic portion of a polymer. Examples of macrocyclic compounds are cyclodextrins.

[0033] The plasticizer is selected from linear polyols and / or non-macrocyclic saccharides. Without being bound by theory, such plasticizers are more flexible in their structure, resulting in softer nonwoven materials and increased application efficiency within the nonwoven fiber structure. Plasticizers that are macrocyclic result in stiffer materials. Furthermore, macrocyclic compounds tend to increase hydrophobicity, which may be undesirable in certain nonwoven applications.

[0034] The linear polyol is selected from one or more of mannitol, maltitol, xylitol and sorbitol. The non-macrocyclic saccharide is selected from one or more of glucose, mannose, fructose, sucrose, sucralose, sucrose esters, hydrolyzed starch or dextrin.

[0035] In terms of the plasticizer, hydrolyzed starch is a product of chemical or enzymatic processing of starch from various natural sources. Hydrolyzed starch can be hydrogenated and contain a mixture of polyols. Hydrolyzed starch is a source of sorbitol.

[0036] Furthermore, it has surprisingly been found that the aqueous binder composition according to the present invention can act as a binder in airlaid nonwoven materials, resulting in materials exhibiting both significantly higher strength and elongation than conventional synthetic binders used in the industry. Compared to other cationic polyelectrolytes, chitosan imparts a higher dry tensile index, and in particular a higher wet tensile index, to materials treated with the binder composition. Preferably, the binder composition contains at least 50% by weight, more preferably at least 60% by weight, more preferably at least 70% by weight, even more preferably at least 80% by weight, and most preferably at least 90% by weight of bio-based, i.e., naturally occurring, components.

[0037] Experiments have shown that binder compositions according to the present disclosure, which include chitosan (a cationic polyelectrolyte) in the composition without the presence of an anionic counterion, can provide better flexibility and softness to nonwoven materials compared to binder compositions that include polyelectrolyte complexes that include cations and anions.

[0038] In binder compositions according to the present disclosure, cationic polyelectrolytes containing chitosan and substantially no anionic polyelectrolyte counterions have been found to be better able to spread within nonwoven materials, resulting in more uniform distribution. Without being bound by theory, it is believed that the absence of electrostatic interactions between the cationic polyelectrolytes and the anionic polyelectrolytes results in a more expanded shape of the cationic polyelectrolyte. When the cationic polyelectrolyte interacts with the anionic counter component, the resulting polyelectrolyte complex exhibits a more helical structure. This expanded shape is believed to allow the cationic polyelectrolyte to better spread within the nonwoven structure. This results in stronger and more flexible nonwoven materials compared to those using PEC binder compositions, as the chitosan acts as a binding component, connecting both itself and the fibers within the airlaid nonwoven material. The synergistic effect between the cationic polyelectrolytes, including chitosan, and the plasticizer results in compositions suitable for use as nonwoven binders, capable of achieving both strength and elongation of treated materials comparable to those of conventional synthetic binders.

[0039] In one embodiment, the aqueous binder composition is substantially free of anionic polyelectrolytes. If a significant amount of anionic polyelectrolytes is present in the composition, the cationic and anionic polyelectrolytes will form polyelectrolyte complexes (PECs), which will impair the functionality of the binder composition, as discussed above.

[0040] Since chitosan requires an acidic environment to be in its cationic form, it is important that the aqueous binder composition has a pH of less than 7. Preferably, the pH of the composition is less than 6.5, and preferably the pH of the composition is between 1.8 and 5.

[0041] In one embodiment, the aqueous binder composition may further comprise a solvent selected from distilled water, tap water, and deionized water.

[0042] The amount of each component of the bio-based aqueous binder composition will depend on the intended use of the composition and the required properties necessary for that use, such as strength, flexibility, elongation, water repellency, absorbency, cushioning, insulating properties and / or filtration properties.

[0043] In one embodiment, the aqueous binder composition includes 0.01 to 11 wt %, for example 0.01 to 8 wt %, 0.01 to 5 wt %, or 0.01 to 2 wt % of an acid.

[0044] In one embodiment, the aqueous binder composition contains 0.05 to 15% by weight of a plasticizer, 0.05 to 14% by weight of a plasticizer.

[0045] In one embodiment, the aqueous binder composition comprises 2 to 14 wt %, preferably 5 to 14 wt %, preferably 5 to 10 wt % of a plasticizer.

[0046] In one embodiment, the aqueous binder contains 1 wt % or more, for example 2 wt % or more and less than 15 wt % of a plasticizer. In one embodiment, the aqueous binder contains 1 to 10 wt % of a plasticizer.

[0047] In one embodiment, the cationic polyelectrolyte in the aqueous binder composition comprises chitosan.

[0048] In one embodiment, the aqueous binder composition comprises 0.005 to 10 wt %, preferably 0.005 to 5 wt %, and even more preferably 0.5 to 2.5 wt % chitosan, with the wt % of chitosan being optimized based on the desired viscosity.

[0049] In one aspect, the acid is selected from one or more of acetic acid, acetylsalicylic acid, adipic acid, benzenesulfonic acid, camphorsulfonic acid, citric acid, citric acid monohydrate, dihydroxyfumaric acid, formic acid, glycolic acid, glyoxylic acid, hydrochloric acid, lactic acid, malic acid, malonic acid, maleic acid, mandelic acid, oxalic acid, para-toluenesulfonic acid, phthalic acid, pyruvic acid, salicylic acid, sulfuric acid, tartaric acid, and succinic acid, preferably lactic acid.

[0050] In one embodiment, the aqueous binder composition comprises chitosan as the cationic polyelectrolyte, lactic acid as the acid, and at least one of sorbitol, hydrolyzed starch, xylitol, and maltitol as the plasticizer. Preferably, the plasticizer comprises hydrolyzed starch.

[0051] In one embodiment, the aqueous binder composition further comprises at least one additive selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, rheology modifiers, fillers, non-ionic polymers, dyes, and pigments, in a concentration of 0 to 50 wt %, more preferably 0 to 30 wt %, of the total weight of the composition, selected depending on the application method and the expected properties of the final material.

[0052] The binder composition according to the present disclosure can be easily applied to a variety of nonwoven materials, such as wet-laid nonwovens, air-laid nonwovens, and carded nonwovens. Because carded nonwoven materials are relatively dense, foam impregnation is a suitable and energy-efficient alternative for applying the binder. This foam impregnation requires that the binder be easily foamable with a common foaming agent. The binder composition according to the present disclosure has proven to be easily foamable with a common foaming agent and easy to apply to carded nonwovens by foam impregnation. Therefore, by treating a carded nonwoven material with a composition according to the present disclosure, the binder can be efficiently applied to the material by foam impregnation, providing a carded nonwoven material with excellent strength.

[0053] In one embodiment, the aqueous binder composition includes at least one foaming agent selected from one or more of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

[0054] The catalyst may be selected from catalysts based on Lewis bases and Lewis acids, such as clays, colloidal or non-colloidal silica, dialdehydes, organic amines, organic amides, quaternary amines, metal oxides, metal sulfates, metal chlorides, urea sulfates, urea chlorides, and silicates.

[0055] The preservative may be selected from one or more of a fungicide, a bactericide, a pharmaceutical preservative, a cosmetic preservative, and a food preservative. The inclusion of a preservative helps inhibit mold growth in the binder composition.

[0056] The filler may be selected from one or more of gum arabic, konjac glucomannan, organic fillers such as wood flour, starch soy flour, olive seed flour, cork flour, corn cob, rice bran / rice husk, and inorganic fillers such as calcium carbonate, glass fiber, kaolin, talc and mica, and other fillers known to those skilled in the art.

[0057] In one embodiment, the aqueous binder composition comprises 0.5-2.5 wt.% chitosan, 2-15 wt.% plasticizer, 0.05-3 wt.% acid, and optionally 0.05-10 wt.% of at least one or more additives selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinkers, rheology modifiers, fillers, nonionic polymers, dyes, and pigments. In a further embodiment, the plasticizer is present in an amount of 2-14 wt.%.

[0058] In a second general aspect, the present invention is a method for treating a nonwoven material with a bio-based binder composition, the method comprising: a) providing a binder composition comprising an acid, a plasticizer, and a cationic polyelectrolyte comprising chitosan, wherein the chitosan has a degree of deacetylation of 66 to 100%, the acid in the binder composition being a Brønsted acid and / or a Lewis acid, the Brønsted acid being selected from any organic acid and / or inorganic acid, the Lewis acid being selected from any cationic monovalent or polyvalent atom, and the cationic polyelectrolyte not forming a complex with an anionic polyelectrolyte; b) optionally diluting the binder composition provided in step a); c) applying the binder composition of step a) or step b) to the nonwoven material by applying the binder composition to the nonwoven web that is being formed, wherein the binder composition applied comprises 0.005 to 20 wt. % chitosan and 0.5 wt. % to less than 15 wt. % plasticizer, the plasticizer being selected from one or more of glycerol, mannitol, maltitol, xylitol, and sorbitol, and / or a linear polyol selected from glucose, mannose, fructose, sucrose, sucralose ... applying the binder composition to a nonwoven material, the binder composition comprising a plasticizer, a sugar which is a non-macrocyclic sugar selected from one or more of cellulose esters, hydrolyzed starch, or dextrin, 0.01 to 30 wt. % of an acid, and optionally 0.05 to 10 wt. % of at least one or more additives selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinking agents, rheology modifiers, fillers, nonionic polymers, dyes, and pigments; d) optionally curing the treated nonwoven material, preferably at a temperature of 20 to 200 degrees Celsius; The present invention relates to a method of treating a nonwoven material with a bio-based binder composition, comprising:

[0059] The bio-based binder composition applied may be any bio-based binder composition according to the first aspect.

[0060] In one embodiment, the nonwoven material treated according to the methods disclosed herein is selected from one or more of an air-laid nonwoven material, a wet-laid nonwoven material, and a carded nonwoven material.

[0061] In one embodiment, the nonwoven material is substantially based on natural fibers such as wood fibers (e.g., pulp), fluff pulp, hemp fibers, or man-made bio-based fibers such as viscose, lyocell, and polylactic acid (PLA).

[0062] The method according to the present invention results in nonwoven materials with improved strength and elongation properties comparable to those of nonwovens bonded with conventional synthetic binders, making it possible to replace conventional synthetic binders with more environmentally friendly bio-based alternatives without compromising the mechanical properties of the nonwoven material.

[0063] In one embodiment of the present invention, the binder composition in step b) is diluted to an aqueous binder composition comprising 0.5-2.5 wt. % chitosan, 2 wt. % to less than 15 wt. % plasticizer, 0.05-3 wt. % acid, and optionally 0.05-10 wt. % of at least one or more additives selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinking agents, rheology modifiers, fillers, nonionic polymers, dyes, and pigments. In a further embodiment, the binder composition is diluted so that the composition comprises 2-14 wt. % plasticizer.

[0064] The binder composition can be applied, for example, by spraying the binder composition onto the nonwoven material, by painting the binder composition onto the nonwoven material, by impregnating the nonwoven material with the binder composition, or by foam-impregnating the nonwoven material with the binder composition.

[0065] In one embodiment, curing is carried out at a temperature between 20 and 200 degrees Celsius. Preferably, curing is carried out at above 135 degrees Celsius, preferably above 150 degrees Celsius.

[0066] In one aspect, the method results in high elongation of the treated nonwoven fabric, preferably the method results in an elongation of at least 4%, preferably at least 5%. As used herein, elongation means total elongation at break measured according to standard EDANA 20.2-89.

[0067] In a third general aspect, the present invention relates to a nonwoven material treated according to the method defined in any of the preceding aspects.

[0068] In one embodiment, the nonwoven material exhibits an elongation of at least 4% after treatment with the aqueous binder composition defined in any one of the preceding embodiments. Preferably, the elongation is at least 5%. The elongation is measured according to EDANA 20.2-89.

[0069] In another general aspect, the present invention relates to the use of an aqueous binder composition according to any one of the preceding aspects for treating nonwoven materials, preferably to provide excellent mechanical properties and other desirable properties to various types of nonwoven materials. DETAILED DESCRIPTION OF THE INVENTION

[0070] The present invention will now be described in detail.

[0071] As used herein, "wt %" refers to the weight percent of a component or components based on the total weight of the compound or composition.

[0072] As used herein, "about" refers to a measurable value, such as an amount, that is intended to encompass a variation of no more than + / -5%, more preferably no more than + / -1%, and even more preferably no more than + / -0.1% of the specified value, to the extent that one of ordinary skill in the art would understand that such variation would be appropriate for practicing the disclosed invention, provided that the value to which "about" refers is itself specifically disclosed.

[0073] As used herein, a wet-laid nonwoven material refers to a nonwoven material produced by a wet-laid process. Wet-laid nonwovens can be produced using natural fibers such as wood fibers (e.g., pulp), fluff pulp, or hemp fibers, or man-made bio-based fibers such as viscose, lyocell, and PLA. Small or significant amounts of synthetic fibers, such as polyester (PES), polyethylene terephthalate (PET), polypropylene (PP), and inorganic fibers such as glass fibers, may also be present in wet-laid nonwoven materials. Wet-laid nonwoven materials can be used in applications such as, but not limited to, napkins, tablets or tablecloths, tabletop products such as wipes and wet wipes, hygiene products such as diapers or feminine hygiene products, agricultural nonwovens such as mulch films, air filtration materials, tea bags, coffee filters, food pads, geotextiles, and wallpaper.

[0074] As used herein, airlaid nonwoven materials refer to nonwoven materials produced by the airlaid (drylaid) process. Airlaid nonwoven fabrics can be produced from natural fibers such as wood fibers (e.g., pulp), fluff pulp, or hemp fibers, or man-made bio-based fibers such as viscose, lyocell, and PLA. Small or substantial amounts of synthetic fibers, such as PES, PET, and PP, can also be present in airlaid nonwoven materials. Airlaid nonwoven materials can be used in applications such as, but not limited to, hygiene applications such as baby diapers, feminine hygiene products, and adult care products; tabletop products such as napkins or tablets, tablecloths; filter materials; automotive nonwovens; tea bags and coffee filters; medical nonwovens used in face masks, surgical gowns, and hair covers; food packaging materials and food pads; wipes and wet wipes; and geotextiles.

[0075] As used herein, a carded nonwoven material refers to a nonwoven material produced by a carding process. Carded nonwovens can be produced from natural fibers such as wood fibers (e.g., pulp), fluff pulp, or hemp fibers, or man-made bio-based fibers such as viscose, lyocell, and PLA. Small or significant amounts of synthetic fibers, such as PES, PET, and PP, can also be present in carded nonwovens. Carded nonwovens can be used in applications such as, but not limited to, hygiene applications such as baby diapers, feminine hygiene products, and adult care products; filter materials; automotive nonwovens; tea bags and coffee filters; medical nonwovens used in face masks, surgical gowns, and hair covers; food packaging materials and food pads; wipes and wet wipes; geotextiles; building materials for insulation and roofing; carpets, wallpaper, mattresses, and agricultural nonwovens.

[0076] As used herein, a surfactant is a molecule that includes a hydrophilic "head" and a hydrophobic "tail."

[0077] As used herein, a polyelectrolyte is a polymer whose repeating units bear charged groups.

[0078] The invention is further described in the following examples, which do not limit the scope of the invention described in the claims. Experimental Section Two different binder compositions, as defined in Table 1, were prepared. [Table 1]

[0079] Example 1: Spray application of Binder A to wet-laid nonwoven material

[0080] Unbonded cellulosic fiber blend wet-laid material was used as the substrate. The material was added onto a conveyor belt traveling at various speeds (3 m / min, 5 m / min, and 7 m / min). Binder A was diluted from 26% dry weight (measured with a VWR moisture analyzer) to 2.5% dry weight and sprayed onto the wet-laid nonwoven material. The wet-laid nonwoven material was then cured by passing it through a 2-m-long oven heated to 160°C. After this treatment, the nonwoven material was conditioned overnight at 23°C and 50% RH. Tensile tests were then performed on 50 mm x 250 mm cut samples using a Testometric M250-2.5AT tensile tester. Seven specimens were measured per test. Both dry and wet tensile tests were performed. For comparison, dry and wet tensile tests were performed on wet-laid nonwoven material without a binder applied. For wet tensile tests, a Finish cup was used and the specimens were immersed in water for 15 seconds. The results of the dry tensile tests are shown in Table 2, and the results of the wet tensile tests are shown in Table 3. All values ​​are average values. [Table 2] [Table 3]

[0081] From Example 1, it can be concluded that the binder enhances the mechanical properties of the wet-laid nonwoven material in both the wet and dry states. The increase in tensile index required for a particular application can be easily adjusted by tailoring the addition of the binder composition.

[0082] Example 2 - Application of Binder B to Airlaid and Wetlaid Nonwoven Materials by Impregnation Binder B was diluted from 27% dry weight (measured with a VWR moisture analyzer) to 14% dry weight and added between two compression rolls of a Wichelhaus GmbH horizontal padder. The roll speed was set at 11.6 m / min, and the pressure between the rolls was set at 0.1 MPa. The materials used in this study were air-laid nonwovens (fluff pulp fibers) and wet-laid nonwovens (mixed cellulose fibers). After impregnation, the materials were placed on a conveyor belt at a speed of 5 m / min and passed through a 3-m-long oven heated to 160°C. The materials were acclimatized overnight at 23°C and 50% humidity. Tensile tests were then performed on 50 mm x 250 mm cut samples using a Testometric M250-2.5AT tensile tester. For comparison, tensile tests were also performed on wet-laid and air-laid nonwoven materials without binder. Ten specimens were measured per test. The results of the tensile tests are shown in Table 4. All values ​​are average values. [Table 4]

[0083] Table 4 shows that both the flexibility (elongation) and strength (tensile index) of both the wet-laid and air-laid nonwoven materials are substantially increased. Note that the air-laid nonwoven material had an elongation of 5.4% after application of the binder composition, meeting the high flexibility requirements of many of the applications in which air-laid nonwovens are used.

[0084] Example 3: Foamability of Binder A with two different blowing agents.

[0085] The foaming properties of Binder A were evaluated with two different foaming agents: a non-ionic foaming agent (Glucopone 215 UP) and a zwitterionic (amphoteric) foaming agent (Ammonyx LO).

[0086] Binder A was diluted from 26% dry weight (measured with a VWR moisture analyzer) to 14% dry weight. 100g of the diluted Binder A and 1g of each blowing agent were added to a 250ml beaker. The mixture was mixed for 5 minutes at 1500 rpm using a propeller. The foam height was measured immediately after mixing and 5 minutes after mixing was completed. The results are shown in Table 5 below. [Table 5]

[0087] This experiment demonstrated that Binder A could be foamed using any of the foaming agents tested, and the foam remained stable for at least 5 minutes, demonstrating that the binder can be smoothly applied by foam impregnation.

[0088] Example 4: Foam impregnation of carded nonwoven material with binder A

[0089] Binder A was diluted from 26% dry weight (measured with a VWR moisture analyzer) to 10% dry weight. 1.67 g of Glucopon 215 UP (foaming agent, nonionic surfactant) was added to 200 g of the diluted mixture, and the mixture was vigorously stirred for 60 seconds at 2000 rpm using an IKA Werke overhead stirrer-mounted disperser. A dense, stable foam was observed. The foam was added between two compression rolls of a Wichelhaus GmbH horizontal padder. The roll speed was set to 11.6 m / min, and the inter-roll pressure was set to 0.1 MPa. A viscose carded nonwoven fabric was passed through the rolls. The nonwoven material was then dried for 3 minutes in a Termax oven set at 170°C. The material was acclimatized overnight at 23°C and 50% RH. Tensile tests were then performed on 50 mm x 250 mm cut samples using a Testometric M250-2.5AT tensile tester. For comparison, tensile tests were also performed on carded nonwoven material without binder. Eight specimens were measured per test. The tensile test results are shown in Table 6. All values ​​are average values. [Table 6]

[0090] Viscose carded nonwovens themselves are very elastic due to the long staple fibers that make up the material. By applying a binder composition, a stiffer and stronger material can be achieved, as evidenced by the increased tensile stiffness index of carded nonwoven materials treated with the foamed binder composition.

Claims

1. 1. A bio-based aqueous binder composition for nonwoven materials, the binder composition comprising an acid, a plasticizer, and a cationic polyelectrolyte comprising chitosan; the chitosan has a degree of deacetylation between 66 and 100% and the binder composition contains between 0.005 and 20% by weight of chitosan; the acid in the aqueous binder composition is a Brønsted acid and / or a Lewis acid, the Brønsted acid being selected from any organic and / or inorganic acid, the Lewis acid being selected from any cationic monovalent or polyvalent atom, the aqueous binder composition preferably comprising 0.01 to 30% by weight of acid, the aqueous binder composition comprises 0.5% to less than 15% by weight of a plasticizer, the plasticizer being a linear polyol selected from one or more of mannitol, maltitol, xylitol, and sorbitol, and / or a saccharide which is a non-macrocyclic saccharide selected from one or more of glucose, mannose, fructose, sucrose, sucralose, sucrose esters, hydrolyzed starch, or dextrin; the pH of said binder composition is less than 7; The cationic polyelectrolyte does not form a complex with the anionic polyelectrolyte; Bio-based aqueous binder compositions for nonwoven materials.

2. The aqueous binder composition of claim 1 , which is substantially free of anionic polyelectrolytes.

3. 3. The aqueous binder composition of claim 1 or claim 2, comprising 0.01 to 11 wt. % of an acid, such as 0.01 to 5 wt. % or 0.01 to 2 wt. %.

4. 4. The aqueous binder composition of claim 1, comprising at least 1 wt. %, for example at least 2 wt. %, but less than 15 wt. % of a plasticizer.

5. 5. The aqueous binder composition according to any one of claims 1 to 4, comprising 0.005 to 10 wt. % chitosan, preferably 0.005 to 5 wt. % chitosan, even more preferably 0.5 to 2.5 wt. % chitosan.

6. 6. The aqueous binder composition according to any one of claims 1 to 5, wherein the acid is selected from one or more of acetic acid, acetylsalicylic acid, adipic acid, benzenesulfonic acid, camphorsulfonic acid, citric acid, dihydroxyfumaric acid, formic acid, glycolic acid, glyoxylic acid, hydrochloric acid, lactic acid, malic acid, malonic acid, maleic acid, mandelic acid, oxalic acid, para-toluenesulfonic acid, phthalic acid, pyruvic acid, salicylic acid, sulfuric acid, tartaric acid and succinic acid, preferably lactic acid.

7. 7. The aqueous binder composition of any one of claims 1 to 6, wherein the composition further comprises at least one additive selected from one or more of antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinking agents, rheology modifiers, fillers, non-ionic polymers, dyes, and pigments, and the concentration of the additive is 0 to 50 wt%, more preferably 0 to 30 wt%.

8. 8. The aqueous binder composition of claim 1, wherein the composition further comprises at least one foaming agent selected from one or more of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

9. 9. The aqueous binder composition of claim 1, wherein the composition comprises 0.5 to 2.5 wt. % chitosan, 2 to less than 15 wt. % plasticizer, 0.05 to 3 wt. % acid, and optionally 0.05 to 10 wt. % of at least one or more additives selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinking agents, rheology modifiers, fillers, non-ionic polymers, dyes, and pigments.

10. a) providing a binder composition comprising an acid, a plasticizer and a cationic polyelectrolyte comprising chitosan, the chitosan having a degree of deacetylation of 66-100%, the acid in the binder composition being a Brønsted acid and / or a Lewis acid, the Brønsted acid being selected from any organic and / or inorganic acid, the Lewis acid being selected from any cationic monovalent or polyvalent atom, and the cationic polyelectrolyte not complexed with an anionic polyelectrolyte; b) optionally diluting the binder composition provided in step a); c) applying the binder composition of step a) or step b) to the nonwoven material by applying the binder composition to the formed nonwoven web, wherein the binder composition applied comprises 0.005 to 20 wt. % chitosan and 0.5 wt. % to less than 15 wt. % plasticizer, the plasticizer being selected from one or more of glycerol, mannitol, maltitol, xylitol, and sorbitol, and / or a linear polyol selected from glucose, mannose, fructose, sucrose, sucralose ... applying the binder composition to a nonwoven material, the binder composition comprising a plasticizer, the plasticizer being a sugar which is a non-macrocyclic sugar selected from one or more of cellulose esters, hydrolyzed starch, or dextrin, 0.01 to 30 wt. % of an acid, and optionally 0.05 to 10 wt. % of at least one or more additives selected from antifoaming agents, blowing agents, wetting agents, coalescing agents, catalysts, surfactants, emulsifiers, preservatives, crosslinking agents, rheology modifiers, fillers, nonionic polymers, dyes, and pigments; d) optionally curing the treated nonwoven material, preferably said curing being carried out at 20-200 degrees Celsius; 1. A method of treating a nonwoven material with a bio-based binder composition, comprising:

11. 11. The method of claim 10, wherein the nonwoven material is selected from one or more of an air-laid nonwoven material, a wet-laid nonwoven material, and a carded nonwoven material.

12. 12. The method according to any one of claims 10 and 11, wherein the nonwoven material is substantially based on natural fibres such as wood fibres (e.g. pulp), fluff pulp, hemp fibres or man-made bio-based fibres such as viscose, lyocell and polylactic acid (PLA).

13. 13. The method of any one of claims 10 to 12, wherein the binder composition is applied to the nonwoven material by spraying the binder composition onto the nonwoven material, painting the binder composition onto the nonwoven material, impregnating the nonwoven material with the binder composition, or foam-impregnating the nonwoven material with the binder composition.

14. 14. The method according to any one of claims 10 to 13, wherein the method results in a high elongation of the treated nonwoven material, preferably the method results in an elongation of the nonwoven material of at least 4%, preferably at least 5%, said elongation being the elongation at break measured according to standard EDANA 20.2-89.

15. A nonwoven material treated according to the method of any one of claims 10 to 14.

16. 16. The nonwoven material according to claim 15, wherein the nonwoven material exhibits an elongation of at least 4%, preferably at least 5%, said elongation being the elongation at break measured according to standard EDANA 20.2-89.

17. 10. Use of the aqueous binder composition according to any one of claims 1 to 9 for treating nonwoven materials.

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