Heavy metal-free leather fiber material based on vegetable-tanned leather fibers

Abstract

The invention relates to a leather fiber material containing a) at least 55% by weight vegetable-tanned leather fibers, b) Binders, and, preferably low-heavy-metal or heavy-metal-free additives, and c) Leather scraps from heavy metal-free tanning and / or fibers from fiber recycling and / or natural fibers and / or synthetic fibers. The leather fiber material is preferably low in or free of heavy metals. The invention further relates to a laminate, a laminate panel, a molded wood substitute or a surface decoration containing or consisting of the leather fiber material according to the invention. The invention further relates to the use of the leather fiber material or the laminate according to the invention in the furniture industry, in the interior design industry and free-form construction or in the shoe industry.

Description

Field of the invention

[0001] The invention relates to a leather fiber material containing a) at least 55% by weight of vegetable-tanned leather fibres, b) binders and, preferably low-heavy metal or heavy metal-free, additives, and c) Leather trimmings from heavy metal-free tanning and / or fibres from fibre recycling and / or natural fibres and / or synthetic fibres.

[0002] The leather fiber is preferably low in or free from heavy metals.

[0003] The invention further relates to a laminate, a laminated board, a molded wood substitute or a surface decoration containing or consisting of the leather fiber material according to the invention. The invention further relates to the use of the leather fiber material according to the invention or the laminate in the furniture industry, in the interior design industry and free-form construction or in the shoe industry. Background of the invention

[0004] Shoes, bags, and other durable products have traditionally been made from leather for many centuries. Leather is derived from a waste product of meat production and is produced using a complex process. For about 100 years, methods have been developed to reuse waste and leftovers from leather production. These are better known as "leather fiber materials" or "leather fiber materials" and are often called "salpa" abroad.

[0005] In the traditional areas of the shoe industry, there has been a trend for years, from the inventor's perspective, toward comfortable shoes, sneakers, and athletic-shoe-like equivalents of the established shoe industry. Leather is also losing importance in this sector for cost and image reasons. Today, shoes and leather goods follow fashion trends far more than established leather values, such as durability, ease of care, and repairability. Materials free of heavy metals and made from recycled materials are also in demand in the furniture industry, both for interior design and free-form construction, as these materials are highly soft and flexible and free of toxins, making them attractive for creating modern surface designs. This opens up new areas of application for such leather fiber materials.

[0006] Contrary to popular belief, conventionally produced genuine leather is usually not a purely natural product. While the raw hide from which leather is made is as natural as a piece of meat, it still undergoes up to 40 processing steps before becoming the finished leather. However, the conventional leather industry uses many chemicals, some of which are environmentally harmful and harmful to health, during the preserving, tanning, and dyeing of hides. These chemicals can remain in the leather and evaporate. Over 80% of the leather produced worldwide today is tanned with chromium, a heavy metal that can cause illness. Hexavalent chromium (chromium VI) is particularly dangerous; it is highly toxic, allergenic, and classified as carcinogenic. Once acquired, a chromium allergy cannot be cured. Trivalent chromium (chromium III) is harmless in small quantities and is even a vital trace element for the human body.However, excessive intake of chromium III also damages the liver, kidneys, and circulatory system. Even if leather has been tanned with chromium III, improper processing can result in chromium VI. This poses a health risk to consumers and is a disaster for groundwater and drinking water in the producing countries. Chrome tanning is used because it is considerably cheaper and faster than tanning with synthetic or vegetable tanning agents. While vegetable tanning is more time-consuming and requires more water than chrome tanning, the wastewater pollutes the environment significantly less because the tanning agents are completely biodegradable. Sewage sludge containing chromium, for example, must be disposed of as hazardous waste (source: www.naturtextil.de).

[0007] Many other harmful substances are used in conventional leather production. Formaldehyde can cause allergies, skin, respiratory, and eye irritation, and is considered carcinogenic. The list goes on. These pollutants are particularly dangerous for the people who produce the leather, but pollutants emitted from leather can also be harmful to consumers. Laboratory tests on conventional leather products repeatedly show that they release harmful substances into the air. These chemicals can be significantly reduced or eliminated entirely during production. Plastic coatings ensure flawless, easy-care, and durable products—unfortunately, a quality consumers do not want to do without. However, this ultra-thin layer compromises the leather's breathability and thus its skin-friendliness.Anyone who accepts or even appreciates a certain patina or irregularity in leather should choose a chrome-free and natural leather product, i.e., uncoated leather. Leather only decomposes residue-free in nature if it is an uncoated natural product.

[0008] Bonded leather (Lefa), leather fiber material, or synthetic leather is a composite material made from shredded leather scraps, sanding dust, and shavings, with the addition of fatliquoring agents, glues, tanning agents, binders, and, if necessary, plasticizers. Shavings are produced when leather is planed, which allows for a uniform thickness. Lefa is also referred to as regenerated leather or reclaimed leather because the production waste generated during leather production is put to further economic use. According to the RAL 060 A2 guidelines (from 2011) and DIN EN 15987, the material may not be labeled or marketed as genuine leather, regardless of the leather fibers it contains. The use of the term bonded leather or bonded leather is regulated by the EN 15987 standard "Leather - Terminology - Main Definitions for the Leather Trade."Products with less than 50 percent leather content may not be labeled as leather fiber. In the trade, leather fiber is also referred to as recycled leather or reconstituted leather. Products such as vegan leather, recast leather, bicast or bycast leather, or faux leather, on the other hand, refer to artificial leather that contains no or only a small amount of leather fiber.

[0009] The leather fiber material according to the invention can meet all of the aforementioned requirements and open up areas of application for initiating sustainable circular economy processes (craddle to craddle). In the Federal Republic of Germany, the Act to Promote the Circular Economy and Ensure Environmentally Sound Waste Management (Circular Economy Act, KrWG) regulates waste management. According to Section 6 of the KrWG, waste prevention and management measures are ranked as follows: 1. Avoidance, 2. Preparation for reuse, 3. Recycling, 4. other uses, in particular energy recovery and backfilling, 5. Elimination.

[0010] Based on the ranking presented above, the KrWG (Waste Management Act) gives priority to the measure that best ensures the protection of people and the environment in the production and management of waste, taking into account the precautionary and sustainability principles. The entire life cycle of the waste must be considered when considering the impacts on people and the environment. In particular, the following must be taken into account: 1. the expected emissions, 2. the degree of conservation of natural resources, 3. the energy to be used or generated and 4. the accumulation of pollutants in products, in waste for recovery or in products derived therefrom.

[0011] The technical feasibility, economic feasibility and social consequences of the measure must be taken into account.

[0012] The leather fiber material according to the invention effectively contributes to waste prevention by recycling plant and animal fiber materials and therefore meets essential criteria of the KrWG.

[0013] According to the latest used textile study presented by the bvse (Federal Association for Secondary Raw Materials and Waste Disposal) in June 2020, the actual collection volume in Germany continued to increase, reaching 1.3 million tons in 2018, 300,000 tons more than in 2013.

[0014] Of the 1.3 million tons collected, a total of 62 percent of used textiles were sold secondhand in 2018; in 2013, the corresponding figure was 54 percent. Given the overall poor collection quality, this could only be achieved through "high, cost-intensive manual sorting," Wittmann said, describing the efforts of the sorting companies and the cost burden on the industry.

[0015] A further 14 percent of used textiles were processed into cleaning rags and insulation materials. Demand thus fell significantly compared to 2013, when 21 percent of the collected volume was recycled this way. According to the bvse (German Association of Waste Management), a further twelve percent of the volume was recycled fibers. The incineration rate (thermal recycling / substitute fuels and waste for disposal) increased from eight percent in 2013 to twelve percent in 2018. The waste for disposal from sorting contained in this process also increased, amounting to approximately 53,000 tons in 2018 (2015: 20,000 tons).

[0016] Fiber recycling produces approximately 60% shredded fibers and 40% dust. Today, the shredded material is used only for low-value applications (painter's fleece, automotive insulation, etc.). The value of these fibers as raw materials for high-priced recycled materials thus remains largely untapped.

[0017] In the state of the art, leather fibres based on recycled fibres are therefore largely unknown.

[0018] EP 076189 A1, for example, relates to a microporous sheet material as a substrate for artificial leather, obtainable by impregnating a nonwoven fabric with an elastic polymer and subsequently coagulating the impregnated polymer, wherein the nonwoven fabric is a mixture of (a) an aromatic polyester fiber (fiber A) and (b) a polyolefin or aliphatic polyamide fiber (fiber B), and the fibers A and B are scattered in a specific manner in the nonwoven fabric.

[0019] JP H08113819 A (published on May 7, 1996) teaches a net-like, antistatic fiber and its production. This fiber consists of mixed fibers containing at least one ethylene-vinyl alcohol copolymer and one ester polymer and has a three-dimensional net-like structure. The fiber is highly fibrillated and possesses excellent antistatic, dirt-repellent, and antibacterial properties, as well as high strength and dyeability. Accordingly, the fiber can be used as woven, knitted, or nonwoven fabric and has a wide range of applications, such as clothing, warming materials, artificial leather, absorbent materials for sanitary products, protective clothing, curtains, cloth, filters, etc.

[0020] However, according to the definition in standard EN 15987, the products according to EP 076189 A1 and JP8113819 are not leather fibres and may not be described as leather fibres.

[0021] There is therefore a great need to use recycled fibers as raw materials and to convert them into high-quality products, such as toxin-free or low-toxin leather fibers. Description of the invention

[0022] Conventional leather fibers consist primarily of chrome shavings and vegetable-tanned leather and are therefore not free of toxic substances. Conventional leather fibers generally do not contain fibers from recycled fibers.

[0023] Based on the prior art, the object of the invention was therefore to provide a leather fiber material which consists predominantly of vegetable (vegetable-tanned) leather fibers and in which the leather fraction containing heavy metals is replaced by alternative fibers.

[0024] This object is achieved by the invention by a leather fiber material containing or consisting of a) at least 55% by weight of vegetable-tanned leather fibres, b) Binders and, preferably low-heavy metal or heavy metal-free, additives c) Leather trimmings from synthetic tanning and / or fibres from fibre recycling and / or natural fibres and / or synthetic fibres.

[0025] Common additives include fats, waxes, dyes, bone glue, etc.

[0026] The proportion c) of the leather sections from synthetic tanning and / or fibers from fiber recycling and / or natural fibers and / or synthetic fibers in the leather fiber material according to the invention is preferably at least 10 wt.%, such as 10 wt.%, 15 wt.%, 20 wt.%, 30 wt.% or 35 wt.%.

[0027] In a preferred embodiment of the invention, the leather fiber contains a) at least 55% by weight of vegetable-tanned leather fibres, b) binders and, preferably low-heavy metal or heavy metal-free, additives, c) Fibers from fiber recycling, wherein the fibers from fiber recycling are selected from textile fiber waste and dust from textile recycling, burlap fibers, fibers from the silphi plant, bamboo fibers, jute fibers, cotton fibers, linen fibers, hemp fibers, flax fibers, kenaf fibers, nettle fibers, sisal fibers, and coconut fibers, or mixtures of at least two of these fiber materials. Particularly preferred are jute fibers, cotton fibers, linen fibers, hemp fibers, flax fibers, sisal fibers, and coconut fibers, either as pure fibers or in the form of mixtures of two or more of these fibers.

[0028] In a further preferred embodiment of the invention, the leather fiber material contains a) at least 55% by weight of vegetable-tanned leather fibres, b) Binders and, preferably low-heavy metal or heavy metal-free, additives c) Leather trimmings from synthetic tanning, particularly tanning free from heavy metals.

[0029] The leather trimmings from synthetic tanning are preferably leather trimmings from leather tanning with aldehydes, phenols, acrylates or enzymes.

[0030] Preferably, the leather trimmings from synthetic tanning are leather trimmings from leather tanning with synthans, lignin extracts and / or glutaraldehyde, particularly preferably glutaraldehyde.

[0031] Particular preference was given to leather sections from synthetic tanning with the exclusion of heavy metals, i.e. tanned without heavy metals.

[0032] It is further preferred if the leather sections from synthetic tanning are shavings, in particular from heavy metal-free tanning.

[0033] All this has the advantage that the leather fiber material according to the invention is entirely free of heavy metals or low in heavy metals.

[0034] "Heavy metal-free" in the context of the invention means that the leather fiber or additive is low in heavy metals, with the heavy metals being selected from the group consisting of antimony, arsenic, barium, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium, silver, and tin. Preferably, the leather fiber of the invention is also low in titanium.

[0035] "Low" in the respective heavy metals or titanium means that the leather fiber of the invention or the additive essentially does not contain individual metals or essentially does not contain all of the metals mentioned. It is preferred if the leather fiber of the invention contains the metals mentioned (individually and / or several individual metals or all of them) at most in amounts according to the table below. heavy metal preferred Particularly preferred Particularly preferred antimony <5 arsenic < 20 < 10 <5 barium < 40 < 20 <10 cadmium < 20 < 10 <5 chrome < 1.000 < 150 < 100 Cobalt < 40 < 20 <10 copper < 40 < 20 <10 Lead < 20 < 10 <5 mercury < 2 < 1 <0,5 nickel < 40 < 20 <10 selenium < 40 < 20 <10 Silver < 20 < 10 <5 tin < 40 < 20 <10

[0036] In a further preferred embodiment of the invention, the leather fiber material contains a) at least 55% by weight of vegetable-tanned leather fibres, b) binders, and additives low in or free from heavy metals, and c) natural fibres and / or synthetic fibres.

[0037] The natural fibers selected are preferably selected from regenerated cellulose fibers, such as viscose, modal, lycocell, and cupro; cellulose ester fibers, such as acetate fibers and triacetate fibers; protein fibers, such as regenerated protein fibers, modified soybean protein fibers, zein fibers, casein fibers, and artificial spider fibers; polylactide fibers, alginate fibers, chitin fibers, elastodiene fibers, and bio-based polyamide fibers.

[0038] The synthetic fibers are preferably selected from fibers made of polyester, such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT); polyamide (PA), polyimide, polyamideimide, aramid, polyacrylic, modacrylic, polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), polychloride, elastane, polybenzoxazole, polybenzimidazole, polyurea, melamine, polyphenylene sulfide, Trivynil, elastolefin, elastomultiester, polyvinyl alcohol, vinylal, polycarbonate, polystyrene, styrene-acylate copolymers, ethylene-vinyl acetate copolymers and combinations thereof.

[0039] "Vegetable-tanned leather fibers" are leather fibers tanned with extracts of oak bark, chestnut, spruce bark, quebracho wood, tara pods, olive leaves, rhubarb roots, mimosa bark, coffee beans, or other natural substances. Preferably, the leather fiber of the invention contains at least 55% leather fibers tanned with oak bark, chestnut, spruce bark, quebracho wood, tara pods, olive leaves, rhubarb roots, mimosa bark, coffee beans, or extracts thereof, or other natural substances.

[0040] The respective percentages by weight, e.g. of vegetable-tanned leather fibers, binders, etc. in the various embodiments of the leather fiber material of the invention are preferably based on the total weight of the overall composition.

[0041] As already stated for the individual embodiments, the leather fiber of the invention contains at least 55% by weight of vegetable-tanned leather fibers. Preferably, the leather fiber of the invention contains more than 55% by weight, such as 56% by weight, 57% by weight, 58% by weight, or 59% by weight, more preferably at least 60% by weight, particularly preferably at least 65% by weight, 70% by weight, or more, of vegetable-tanned leather fibers.

[0042] The fiber portion in the leather fiber material of the invention that does not consist of leather, leather scraps, or leather fibers may consist of only one fiber type. However, it is preferred if this fiber portion comprises a mixture of two or more fiber types, made from recycled fibers and / or natural fibers and / or synthetic fibers, in order to achieve maximum dimensional stability and strength. It is particularly preferred if this fiber portion also contains fiber fragments, which are generally difficult to recycle.

[0043] The leather fiber of the invention preferably contains fibers made from the above-mentioned natural polymers, particularly preferably natural fiber materials that can be obtained from natural raw materials. According to the invention, both plant and animal fiber materials are suitable. While plant fibers consist predominantly of cellulose, animal fibers, such as human or animal hair, are composed of protein compounds. This embodiment has the advantage that the formation of microplastics from the leather fiber of the invention can be completely prevented.

[0044] Fibers selected from mineral fibers, glass fibers, or carbon fibers can be added to the leather fiber material according to the invention to develop specific properties. Special properties within the meaning of the invention can be: improving strength in free-form construction or influencing fire protection behavior or other special requirements. In a further embodiment of the invention, the leather fiber material according to the invention therefore contains fibers selected from mineral fibers, glass fibers, or carbon fibers.

[0045] The leather fiber material according to the invention is preferably a flat material and has, for example, a thickness of 0.3 - 6.0 mm, preferably 0.4 to 5 mm, 0.5 to 4 mm, 0.6 to 3 mm or 0.7 to 2 mm.

[0046] The binder is preferably based on or composed of natural latex and / or synthetic latex. Natural latex is cis-1,4-polyisoprene. Suitable synthetic latex compounds include styrene-butadiene rubber (SBR), butadiene-acrylonitrile rubber (NBR), and chloroprene rubber (CR).

[0047] In a further embodiment of the invention, the binder is a thermoplastic binder, preferably selected from thermoplastic binders based on an acrylate, butadiene, styrene or vinyl chloride polymer or a copolymer thereof.

[0048] In a preferred embodiment of the invention, the binder of the fiber material contains or consists of a mixture, wherein the mixture comprises one or more synthetic polymers or copolymers, such as styrene-acylate copolymers, vinyl acetate polymers, polyurethane polymers, polyacrylate polymers or ethylene-vinyl acetate copolymers, and natural latex and / or synthetic latex.

[0049] In a particularly preferred embodiment, the binder is an acrylonitrile-styrene-acrylate copolymer.

[0050] The binder content in the leather fiber material according to the invention is preferably at least 10 wt.%, particularly preferably more than 10 wt.%, such as 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.% or 40 wt.%, particularly preferably 20 wt.% to 30 wt.%.

[0051] In a particularly preferred embodiment of the invention, the leather fiber of the invention contains a) at least 55% by weight of vegetable-tanned leather fibres, b) at least 10 wt.%, preferably 20-30 wt.% binder, (c) At least 10% by weight of leather trimmings from synthetic tanning and / or fibres from fibre recycling and / or natural fibres and / or synthetic fibres, and d) Further additives, preferably low in heavy metals or free of heavy metals, selected from dyes, bleaching agents, water repellents and preservatives.

[0052] In a further embodiment of the invention, the leather fiber material according to the invention may contain further additives selected from dyes, bleaching agents, hydrophobic agents, preservatives, etc.

[0053] Dyes for dyeing fibers, especially natural fibers, are known to those skilled in the art and are used to meet customer requests for colors other than the usually unlevel or random coloring of the leather fiber according to the invention, which is caused by the respective fibers used. Dyes for dyeing natural fibers can be of synthetic or plant origin. Suitable synthetic dyes include, for example, acid dyes (salts of dye sulfonic acids that form compounds with basic components of the fiber matrix and readily absorb into the fiber matrix), substantive dyes (direct dyes), basic dyes, and sulfur dyes. Suitable natural dyes include, for example, indigo, madder red, redwood, yellowwood, logwood, or fisetwood. Preferred dyes are pigment dyes. Dyes from plant raw materials are particularly preferred.

[0054] Suitable hydrophobic agents are vegetable oils and fats (palm oil, sunflower oil, rapeseed oil, soybean oil, coconut oil, palm kernel oil, Turkey red oil), waxes (carnauba wax, montan wax), and synthetic fats (paraffin oil, mineral oil, fatty alcohol, fatty acid esters). Hydrophobic agents are used to adjust the softness and waterproofing of the leather fiber material according to the invention. Hydrophobic agents made from modified natural fats such as rapeseed oil, lecithin, and mineral oils are preferred. Mixtures of these natural, modified fats are particularly preferred.

[0055] Typical preservatives that particularly protect against mold growth include 2-thiocyanate (TCMTB) (benzothiazol-2-ylthio)methylthiocyanate, 4-chloro-3-methylphenol, 2-phenylphenol, and 2-octylisothiazolone. 2-thiocyanate (TCMTB) is preferred.

[0056] In a further aspect, the invention relates to a process for producing the leather fiber material according to the invention.

[0057] In the first step, the raw materials are fed into separate conveyor belts, sorted by type. For example, at least 55% by weight of vegetable-tanned leather fibers are precisely weighed on conveyor belt 1, and the vegetable / textile raw materials are precisely weighed on conveyor belt 2. This ensures that the exact, recipe-compliant weight is always used.

[0058] The raw materials are then crushed in suitable crushing machines, preferably shredders or knife mills, to a size of approximately 0.1 - 1 cm 2Surface shredded (pre-cut). At this stage, the shredding of the residues is generally carried out dry without the addition of water. The pre-shredded fibers are then soaked in water to form a suspension with 3-8 wt. %, preferably 4-7 wt. %, particularly preferably 6-7 wt. % fiber content and 93-94 wt. % water content. This suspension is wet-fibered using fiberizing machines, so-called refiners, preferably cone or disc refiners, to obtain a knot-free, non-spinning fiber slurry consisting of approximately 3-8 wt. % fibers and approximately 92-97 wt. % water. The invention also relates to the ability to mix in fibers with less fiberization effort in order to achieve optimal product properties. The resulting suspension of fibers in water is then transferred to a suitable container with a stirrer, preferably a mixing vat.The transferred amount is measured such that the mass of fibers relative to the total intended batch quantity is in accordance with the recipe. The individual recipe components (e.g. dyes, water repellents, binders, preservatives) are then added while stirring. After the binder has been added, the binder is coagulated with a suitable fixing agent, preferably with a solution of an aluminum salt, and thus fixed to the fiber. The batch is then freed of excess water using a suitable dewatering device. Continuous processing on a Fourdrinier wire dewatering machine, similar to that used in the board and paper industry, is preferably suitable for this purpose. The finished batch is dewatered on the Fourdrinier wire dewatering machine to a residual water content of approximately 70 wt.%.Following the dewatering process, the resulting material is mechanically dewatered using a suitable pressing device to a residual water content of approximately 50 wt.%. The material treated in this way is then passed through a suitable thermal drying device, where it is dried to a residual water content of approximately 9-13 wt.% and then wound onto rolls. Depending on the intended use, it is also possible to dry the material to lower or higher residual water contents. The leather fiber produced in this way can be further densified with a calender as required, but can also be embossed to enhance specific properties (e.g., density, abrasion, strength, appearance, etc.). It can also be sanded to achieve special surface characteristics.

[0059] The resulting leather fiber can then be further refined according to customer requirements, for example, by applying surface coatings or perforating to improve breathability. However, the material can also be marketed without any further finishing if, for example, the originality and visibility of the leather fiber is desired.

[0060] The invention therefore provides, in a preferred embodiment, a process for producing a leather fibre material, preferably low in heavy metals or free of heavy metals, which comprises the following steps: i. Weighing the various components on separate conveyor belts to achieve recipe conformity for subsequent processes ii. Shredding of fibrous materials; iii. Preparing a suspension containing 3-8 wt% fibers and 92-97 wt% water; iv. wet defibration of the fibers in the aqueous suspension to produce a knot-free suspension; v. Dosing of the binder and, if necessary, other additives selected from dyes, hydrophobic agents, preservatives, etc. while stirring; vi. Coagulation of the binders with a salt, e.g. aluminum sulfate vii. Dewatering material; viii. Drying the material; ix. optional densification and embossing of the material; x. optional grinding, perforating, coating, etc. for various applications.

[0061] The resulting leather fiber, especially when it consists exclusively of plant and animal fibers, contains no plastic components, is low in or free of heavy metals, and thus meets all environmental requirements. The formation of microplastics from this leather fiber material is impossible. Furthermore, the leather fiber material according to the invention is compostable and thus can be disposed of in an environmentally friendly manner. Alternatively, the leather fiber material according to the invention can be recycled and thus reused as a raw material.

[0062] The invention further provides a laminate containing or consisting of a leather fiber material of the invention, wherein the leather fiber material of the invention is preferably low in heavy metals or heavy metal-free.

[0063] The laminate according to the invention contains several layers of a leather fiber material according to the invention, preferably at least two or more layers, particularly preferably 2 to 50 layers. The number of layers depends on and is determined by the intended use or application of the laminate.

[0064] The laminate according to the invention can be produced using conventional means and methods generally known to those skilled in the art, e.g., from plywood production. The layers of the laminate according to the invention are bonded to one another with a binder, like conventional laminates. Preferably, a thermoplastic binder is used to bond the layers together. Suitable thermoplastic binders include binders based on an acrylate, butadiene, styrene, or vinyl chloride polymer, or a copolymer thereof. An acrylonitrile-styrene-acrylate copolymer is particularly suitable as a binder.

[0065] The invention further relates to the use of the leather fiber material or the laminate according to the invention in the furniture industry, in the interior design industry and in free-form construction or in the shoe industry.

[0066] The leather fiber material according to the invention is preferably used in the shoe industry for the production of heel caps, heels, outsoles and insoles and as a frame material.

[0067] The invention further provides a laminated board, a molded wood substitute, or a surface decoration containing or consisting of a leather fiber material according to the invention. Preferably, this laminated board, the molded wood substitute, or the surface decoration is based on textile fibers and / or plant fibers or on a leather fiber material that contains textile fibers and / or plant fibers as a fiber component in addition to leather residues.

[0068] The invention is explained in more detail below using two embodiments and a figure. Figures Fig.Figure 1 shows sectional views (10) of various laminates produced from flat leather fiber materials (11, 12) of the invention. The individual layers (11, 12) are bonded together using an acrylonitrile-styrene-acrylate copolymer as a binder. The number of layers (11, 12) and their thickness can vary and depend on the intended use of the laminate. The layers can be dye-free (12) or contain dyes (11). Fig. In the embodiment shown in Figure 1, the laminates (10) each contain eight layers, with a light layer (12) and a darker layer (11) alternating. Different colorings of the layers are achieved by using differently colored starting materials. The leather fiber material of the invention can contain, in addition to vegetable-tanned leather fibers, fibers from fiber recycling and / or natural fibers and / or synthetic fibers. In the embodiment shown here Fig. 1 the light layers contain linen / cotton fibers, and the dark denim fibers from textile recycling. Examples of implementationExample 1 - Manufacturing process

[0069] Vegetable leather waste 55-60% and fibers / dust from fiber recycling 40-45% were ground in a knife mill to a size of about 0.1 - 1 cm 2Surface shredded without adding water. The pre-shredded fibers were soaked in water to form a suspension containing 5% fibers by weight and 95% water by weight. This suspension was wet-fibered using two disc refiners to produce a knot-free, non-spinning fiber pulp consisting of approximately 5% fibers by weight and approximately 95% water by weight. The resulting suspension was then transferred to a mixing vat. The pH was then adjusted to 6.5, and a binder containing 15 to 45% natural latex and a preservative was added while stirring. Once the binder had been added, it was coagulated with a solution of an aluminum salt, thereby fixing it to the fiber. The batch was then freed of excess water using a Fourdrinier wire dewatering machine.The finished batch was dewatered on a fourdrinier wire dewatering machine to a residual water content of approximately 70 wt.%. Following the dewatering process, the resulting material was mechanically dewatered using a suitable pressing device to a residual water content of approximately 50 wt.%. The treated material was then passed through a suitable thermal drying device, where it was dried to a residual water content of approximately 10 wt.% and then wound onto rolls. The material was subsequently tested for its physical properties and rewound for further processing. Example 2 - various leather fiber material tests

[0070] Several different binders were produced according to the procedure in example, whereby the question was how the different binders affect the development of the physical values ​​such as elongation, tear strength but also the density to be achieved of the material. ingredient Mixture 1 Mixture 2 Mixture 3 Mixture 4 Fiber material 55% vegetable leather scraps 20% linen dust 25% jute fibers 60% vegetable leather scraps 40% linen dust 60% vegetable leather residues 40% jute fibers 55% vegetable leather scraps 20% linen dust 25% jute fibers Binder Natural latex 25% by weight 1 Styrene-acrylate copolymer 35 wt.% 1 Ethylene-vinyl acetate copolymers 30 wt.% 1 Natural latex 10 wt% Styrene acrylate copolymer 15 wt% 1 Preservatives 2-Thiocyanomethylthiobenboth. (TCMPT) 0,01 Gew.-% 2 2-Thiocyanomethylthiobenboth. (TCMPT) 0,01 Gew.-% 2 2-Thiocyanomethylthiobenboth. (TCMPT) 0,01 Gew.-% 2 2-Thiocyanomethylthiobenboth. (TCMPT) 0,01 Gew.-% 2 Fatliquor Mixture of rapeseed oil, lecithin 6 wt.% 2 Mixture of rapeseed oil, lecithin 6 wt.% 2 Mixture of rapeseed oil, lecithin 6 wt.% 2 Mixture of rapeseed oil, lecithin 6 wt.% 2 Stretching 25 % 35 % 18 % 15 % Tear value 19 N / mm 2 12 N / mm 2 25 N / mm 2 12N density 0,84 g / cm 3 0,74 g / cm 3 0.76g / cm 3 0,88 g / cm 3 1 Based on the total weight proportion of the organic fiber material and the binder 2 Based on the total weight of the material QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 076189 A1 [0018, 0020] JP H08113819 A

[0019] JP 8113819

[0020] Cited non-patent literature

[0000] DIN EN 15987

[0008] Standard EN 15987

[0008]

Claims

[1] Leather pulp containing a) at least 55% by weight of vegetable-tanned leather fibres, b) binders and, preferably low-heavy metal or heavy metal-free, additives, and c) Leather trimmings from heavy metal-free tanning and / or fibres from fibre recycling and / or natural fibres and / or synthetic fibres. [2] Leather fiber material according to claim 1, containing a) at least 55% by weight of vegetable-tanned leather fibres, b) binders and, preferably low-heavy metal or heavy metal-free, additives, and c) Fibers from fiber recycling, wherein the fibers from fiber recycling are selected from textile fiber waste and dust from textile recycling, burlap fibers, fibers of the silphi plant, bamboo fibers, jute fibers, cotton fibers, linen fibers, hemp fibers, flax fibers, kenaf fibers, nettle fibers, sisal fibers and coconut fibers. [3] Leather fibre material according to one of claims 1 or 2, characterized by that the fibers selected from fiber recycling are jute fibers, cotton fibers, linen fibers, hemp fibers, flax fibers, sisal fibers and coconut fibers. [4] Leather fiber material according to claim 1, containing a) at least 55% by weight of vegetable-tanned leather fibres, b) binders and, preferably low-heavy metal or heavy metal-free, additives, and c) Leather trimmings from synthetic tanning, particularly tanning free from heavy metals. [5] Leather fibre material according to claim 4, characterized by that the leather trimmings from synthetic tanning leather trimmings from leather tanning with aldehydes, phenols, acrylates or enzymes. [6] Leather fibre material according to claim 4 or 5, characterized by that the leather trimmings from synthetic tanning are leather trimmings from leather tanning with synthans, lignin extracts and / or glutaraldehyde, preferably glutaraldehyde. [7] Leather fibre material according to one of claims 4 to 6, characterized by that the leather scraps from synthetic tanning are shavings. [8] Leather fiber material according to claim 1, containing a) at least 55% by weight of vegetable-tanned leather fibres, b) binders, and additives low in or free from heavy metals, and c) natural fibres and / or synthetic fibres. [9] Leather fibre material according to claim 8, characterized by that the natural fibers selected are fibers made from regenerated cellulose, such as viscose, modal, lycocell and cupro; fibers made from cellulose esters, such as acetate fibers and triacetate fibers; protein fibers, such as regenerated protein fibers, modified soybean protein fibers, zein fibers, casein fibers and artificial spider fibers; polylactide fibers, alginate fibers, chitin fibers, elastodiene fibers, and bio-based polyamide fibers. [10] Leather fibre material according to claim 8, characterized bythat the synthetic fibers are selected from fibers made of polyester, such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT); polyamide (PA), polyimide, polyamideimide, aramid, polyacrylic, modacrylic, polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), polychloride, elastane, polybenzoxazole, polybenzimidazole, polyurea, melamine, polyphenylene sulfide, Trivynil, elastolefin, elastomultiester, polyvinyl alcohol, vinylal, polycarbonate, polystyrene, styrene-acylate copolymers, ethylene-vinyl acetate copolymers and combinations thereof. [11] Leather fibre material according to one of the preceding claims, characterized by that the leather fibre contains at least 55% of leather fibres tanned with oak bark, chestnut, spruce bark, quebracho wood, tara pods, olive leaves, rhubarb roots, mimosa bark or coffee beans or extracts thereof or other natural substances. [12] Leather fibre material according to one of the preceding claims, characterized by that the leather fibre is low in or free from heavy metals, in particular free from antimony, arsenic, barium, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium, silver, tin and / or titanium. [13] Leather fibre material according to one of the preceding claims, characterized by that the binder is selected from • Natural latex (cis-1,4-polyisoprene) and / or synthetic latex selected from the latex compounds styrene-butadiene rubber, butadiene-acrylonitrile rubber and chloroprene rubber, or mixtures thereof; and / or • Thermoplastic binders. [14] Leather fibre material according to one of the preceding claims, characterized by that the binder is a thermoplastic binder based on an acrylate, butadiene, styrene or vinyl chloride polymer or a copolymer thereof. [15] Leather fibre material according to one of the preceding claims, characterized by that the binder is an acrylonitrile-styrene-acrylate copolymer. [16] Leather fibre material according to one of the preceding claims, characterized by that the leather fibre further contains additives selected from dyes, bleaching agents, water repellents and preservatives. [17] Leather fibre material according to one of the preceding claims, characterized by that the leather fibre contains at least 60% by weight of vegetable-tanned leather fibres. [18] Leather pulp containing a) at least 55% by weight of vegetable-tanned leather fibres, b) at least 10 wt.% binder, but preferably 20-30 wt.% (c) At least 10% by weight of leather trimmings from synthetic tanning and / or fibres from fibre recycling and / or natural fibres and / or synthetic fibres, and d) Other additives selected from dyes, bleaching agents, water repellents and preservatives. [19] Laminate containing or consisting of a leather fibre material, preferably low in heavy metals or free of heavy metals, according to one of claims 1 to 18. [20] Laminate according to claim 19, containing at least 2 of a leather fiber material according to one of claims 1 to 18. [21] Laminate according to claim 20, characterized by that the at least 2 layers are bonded to each other by means of a thermoplastic binder. [22] Laminate according to claim 21, characterized by that the thermoplastic binder is a binder based on an acrylate, butadiene, styrene or vinyl chloride polymer or a copolymer thereof, preferably an acrylonitrile-styrene-acrylate copolymer. [23] Use of the leather fibre material according to one of claims 1 to 18 or of the laminate according to one of claims 19 to 22 in the furniture industry, in the interior design industry and free-form construction or in the shoe industry. [24] Use of the leather fibre material according to claim 23 in shoe manufacture for back caps, heels, outsoles and insoles and as a frame material. [25] Laminated board, molded wood substitute or surface decoration containing or consisting of a leather fiber material according to one of claims 1 to 18 or a laminate according to one of claims 19 to 22. [26] Laminated board, moulded wood substitute or surface decoration according to claim 25, characterized by that the laminated board, the molded wood substitute or the surface decoration is based on textile fibers and / or vegetable fibers.

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