Nonwoven fabric containing polylactic acid multi-component fibers, and use thereof

Abstract

The present invention relates to a nonwoven fabric containing a fiber composition which comprises a polylactic acid multi-component fiber and optionally further fibers, to a method for producing a molded body from such a nonwoven fabric, to the molded bodies obtained, and to the use of the nonwoven fabric.

Description

[0001] Nonwoven fabric containing polylactic acid multicomponent fibers and its use

[0002] The present invention relates to a nonwoven fabric containing a fiber composition comprising a polylactic acid multicomponent fiber and optionally further fibers, a process for producing a molded article from such a nonwoven fabric and the molded articles obtained, as well as the use of the nonwoven fabric.

[0003] BACKGROUND OF THE INVENTION

[0004] Nonwovens are extremely versatile textile materials that have found widespread use. Nonwoven products are used in many sectors and for many purposes, such as the clothing and automotive industries, construction, and medical sectors. Nonwovens can be adapted to the desired application by selecting the physicochemical properties of the fibers used in their production, the type of fiber laying, compaction, and bonding, the fiber finish, and the manufacturing process.

[0005] There is currently a great demand for nonwovens that meet the ecological requirements for the use of sustainable materials. Fossil-based raw materials such as mineral oil should be avoided wherever possible when producing the fibers used, and the nonwovens and resulting products should be biodegradable and / or compostable. Sustainable production should not negatively impact the application properties of the nonwovens. The fibers currently used to produce nonwovens still require improvement in terms of achieving a good balance between outstanding application properties and environmental compatibility.

[0006] A special application for nonwovens is in plant cultivation, where they are used, among other things, as containers for plant propagation and cultivation, for covering the soil to prevent weeds from growing, for protecting crops from the elements, dirt, and bird droppings, as protective fleece, e.g., for plant transport and shipping, and for protecting straw and hay bales, etc. Nonwovens are also suitable as plant substrates for soilless plant cultivation in greenhouses and open-air cultures, e.g., as hydroponic supports.

[0007] US 10,590,577 B2 describes a device for producing a spunbonded nonwoven from polylactic acid fibers (PLA). The fibers can be monocomponent fibers or multicomponent fibers, whereby the multicomponent fibers can contain a variety of other polymer components in addition to a PLA component, which can also be synthetic polymers of fossil origin. PLA / PLA bicomponent fibers are mentioned only as one possible embodiment, whereby the two PLA components can differ in melting point or in the D(-)-lactic acid content. The production of wet-bonded nonwovens based on PLA multicomponent fibers is not described.

[0008] WO 2017 / 106191 A1 describes nonwovens based on bicomponent fibers with a core-shell structure, wherein the core contains a first polylactic acid polymer (PLA-1) and the shell contains a second polylactic acid polymer (PLA-2). PLA-1 and PLA-2 differ in the composition of the lactic acid monomer units, with PLA-1 generally being more crystalline than PLA-2 and having a higher melting point than PLA-2. PLA-1 can contain a polymeric plasticizer to improve its stretch properties. Biodegradable polymers can be used as polymeric plasticizers. The resulting nonwovens exhibit good mechanical stretch behavior and are suitable for a thermoforming process for the production of coffee and tea capsules.

[0009] US 2023 / 0203757 A1 relates to a packaging material for a pouch-packaged product for oral administration, comprising a wet-laid nonwoven based on cellulose staple fibers and optionally thermoplastic fibers. The thermoplastic fibers can be, among others, PLA / co-PLA bicomponent fibers, e.g., in the form of core-shell fibers with PLA in the core and co-PLA in the shell.

[0010] US 2020 / 0224344 A1 describes a washable plant-based nonwoven substrate comprising an interwoven network of bast fibers and PLA fibers. The PLA fibers can be bicomponent fibers whose components differ in their melting point. The nonwoven substrate is suitable for various wipes, for example, for hygiene and cosmetic applications.

[0011] US 2003 / 0022581 A1 describes nonwovens with fluid management properties for use as a liquid-storing layer in personal care articles. The compositions contain a biodegradable thermoplastic fiber that does not undergo significant heat shrinkage as the binding fiber. This is preferably a multicomponent fiber, specifically based on PLA.

[0012] WO 2015 / 067272 A1 (EP 3065537 B1) describes a plant container and a method for its production, comprising the following steps: a) providing a fiber mixture comprising PLA fibers and a biodegradable fiber, b) using the fiber mixture in a weaving or nonwoven formation process to produce a permeable sheet, c) continuously forming the sheet into a continuous container by bringing the side edges of the material into contact and welding them, d) cutting the continuous container into predetermined lengths, thereby creating separate plant containers, or perforating the continuous container substantially perpendicular to the longitudinal direction at predetermined intervals, thereby enabling separate plant containers to be detached from the continuous container.

[0013] In the process described in WO 2015 / 067272 A1, a monocomponent PLA is used, which becomes thermally weldable by adding a carrier in the form of a biodegradable fiber.

[0014] There is a need for polylactic acid-based nonwovens with improved application properties, particularly high tensile strength and high shrinkage resistance. The nonwovens should contain polylactic acid fibers that are suitable for use in thermal joining processes, especially for welding, even without additional fibers. The nonwovens and molded articles based on them should meet the requirements for sustainable materials and, in particular, be biodegradable and / or compostable.

[0015] Surprisingly, it has now been discovered that nonwovens based on PLA multicomponent fibers, in particular PLA / PLA bicomponent fibers, exhibit a particularly advantageous property profile with regard to thermal joinability, biodegradability, and mechanical properties. This applies especially to the use of wet-fiber nonwovens. The nonwovens are characterized by high tensile strength, especially when wet, low shrinkage, and good air permeability. Specifically, it has been discovered that nonwovens based on PLA multicomponent fibers, in particular PLA / PLA bicomponent fibers, can be thermally joined and, in particular, welded without the need for the addition of further fibers or additives. Fiber compositions containing such PLA multicomponent fibers and nonwovens based thereon are particularly suitable for the production of molded articles by thermal joining, specifically welding.The resulting molded bodies are suitable for use in plant cultivation, especially as plant containers.

[0016] SUMMARY OF THE INVENTION

[0017] A first subject of the invention is a nonwoven fabric containing a fiber composition comprising a) at least one multi-component fiber comprising at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally at least one further fiber different from a).

[0018] In a specific embodiment, the nonwoven fabric contains a fiber composition comprising at least one further biodegradable and / or compostable fiber b). The fibers b) are selected in particular from cellulose-containing natural fibers, man-made cellulose fibers, and mixtures thereof.

[0019] In a special version, the nonwoven fabric is a wet fiber nonwoven fabric.

[0020] The invention further provides a process for producing a shaped body, in which i) a fiber composition is provided which a) comprises at least one multi-component fiber which comprises at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally comprises at least one further fiber b) different from a), ii) the fiber composition provided in step i) is subjected to a wet-laying process to produce a nonwoven fabric, iii) the nonwoven fabric is subjected to a thermal joining step by welding.

[0021] In a specific embodiment, the fiber composition b) provided in step i) comprises at least one biodegradable and / or compostable fiber b).

[0022] A further subject of the invention is a shaped body obtainable by a process as defined above and below.

[0023] Another object of the invention is the use of a nonwoven fabric, as defined above and below, for plant cultivation and agriculture, in particular as a container for the cultivation and cultivation of plants, for covering the soil, for protecting plants from cold and heat, for pollination bags, for protecting the harvested product, as a protective nonwoven fabric for plant transport and shipping, for protecting straw and hay bales and as a plant substrate for soilless plant cultivation, for the production of textile articles, for the thermal and / or acoustic insulation of buildings, vehicles, aircraft, ships, technical installations and household appliances, for filtration applications, packaging, dehumidification bags, hygiene products, personal care products, medical products, cleaning products in the household and I&L sector and products for home furnishing and for filtration.

[0024] A further subject matter of the invention is a container for plants, in particular a cultivation container, comprising or consisting of a shaped body as defined above and below or obtainable by a method as defined above and below.

[0025] Another object of the invention is a method for producing containers for natural materials, preferably for plants, comprising the steps:

[0026] A) Providing a nonwoven fabric as defined above and below;

[0027] B) continuously forming the nonwoven fabric from A) into a continuous container by bringing the side edges of the nonwoven fabric into contact and joining the side edges,

[0028] C) cutting the continuous container into predetermined lengths, thereby obtaining separate plant containers, or wherein the continuous container is perforated substantially perpendicular to the longitudinal direction of the continuous container at predetermined intervals, thereby enabling separate plant containers to be separated from the continuous container.

[0029] DESCRIPTION OF THE INVENTION

[0030] Polylactic acid is also referred to as PLA for short.

[0031] Polylactic acid (PLA) can be produced by direct synthesis, i.e., polycondensation of lactic acid. The production of lactic acid, used as a starting material, is currently primarily biotechnologically through the fermentation of carbohydrates. For example, glucose can be produced from starch through enzymatic hydrolysis, and from this, lactic acid can be produced with the help of Lactobacillus cultures. Alternatively, polylactic acid can be produced by ring-opening polymerization of lactide. The term "machine direction" or "MD" as used herein refers to the running direction of the nonwoven web during production. The term "cross direction" or "CD or CMD" as used herein refers to the direction perpendicular to the machine direction and extending across the width of the nonwoven web.

[0032] The fibers used can be characterized by their fineness, i.e., their weight relative to a specific length. The so-called fineness of the fibers is expressed in dtex (1 dtex = 0.1 tex or 1 gram per 10,000 meters).

[0033] A plastic is considered biodegradable if it can be converted by microorganisms into carbon dioxide, water, mineral salts, and biomass in the presence of oxygen, or into carbon dioxide, methane, mineral salts, and biomass without oxygen. In general, a material is considered biodegradable if a certain reduction in a critical physical or mechanical property is observed after exposure to a defined biological environment for a certain period of time. A critical parameter for the extent of biodegradation of a nonwoven fabric is the decrease in the material's tensile strength.

[0034] A test for "biodegradability in soil" is defined in ASTM D5988, "Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in Soil." According to the compostability specifications of DIN EN 13432:2000-12, the products must be at least 90% degradable into fragments smaller than 2 mm within a maximum of 90 days in an industrial composting facility.

[0035] The nonwovens according to the invention can be, for example, staple fiber nonwovens, spunbonded nonwovens, meltblown nonwovens, or wet-laid nonwovens. In a preferred embodiment, the nonwovens according to the invention are in the form of wet-laid nonwovens.

[0036] Staple fiber nonwovens are made from staple fibers. These fibers are opened and blended before processing. The nonwoven fabric is formed on carding machines with rotating rollers. Higher basis weights can be achieved by using cross-lappers.

[0037] In spunbond technology, the polymers used to produce the fibers are extruded as granules, and the molten polymer is spun into continuous filaments using spinnerets. These filaments are first cooled with air and stretched beneath the spinnerets, then deposited on a collecting belt.

[0038] The meltblown process is similar to spunbond technology. At the nozzle tip, a high-velocity hot gas stream flows around the extruded, molten polymer. The turbulent hot gas flow below the nozzle causes the filaments to stretch. In the wet-laid process, staple fibers are suspended in water. The fiber length is generally up to 30 mm, preferably up to 20 mm. The water-fiber dispersion is then continuously deposited onto a forming fabric to form the nonwoven. The water is extracted, filtered, and recycled.

[0039] The nonwovens according to the invention and the molded articles obtained by the process according to the invention are particularly advantageous for plant cultivation and agriculture. They are preferably used as containers for the propagation and cultivation of plants, for covering the soil for chemical-free weed control, for protecting plants from cold and heat, for protecting the harvested crop, as a protective nonwoven for plant transport and shipping, for protecting straw and hay bales, and as a planting substrate for soilless plant cultivation in greenhouses and open-air cultures, e.g., as a hydroponic support.

[0040] The nonwovens according to the invention are also advantageously suitable for the production of textile articles. They are particularly suitable for use in padding for textile articles such as sportswear and outdoor clothing.

[0041] The nonwovens according to the invention are also advantageously suitable for thermal and / or acoustic insulation, e.g. of buildings, vehicles, aircraft, ships, technical systems and household appliances.

[0042] The nonwovens according to the invention are also suitable for packaging, hygiene products, personal care products, medical products, cleaning products in the household and I&L sector, products for home furnishing, for filtration, etc.

[0043] The nonwoven fabrics according to the invention based on polylactic acid multicomponent fibers and molded articles based thereon have at least one of the following advantages:

[0044] They can be thermally joined and, in particular, welded. Unlike monocomponent polylactic acid fibers, no additional fibers or additives are required.

[0045] The polylactic acid multicomponent fibers are biodegradable and / or compostable. They are suitable as a sole component or in combination with at least one other biodegradable and / or compostable fiber for the production of nonwovens and molded articles that are themselves biodegradable and / or compostable.

[0046] The nonwovens and molded bodies have advantageous mechanical properties.

[0047] They exhibit particularly good tensile properties, both in the x-axis direction (machine direction, MD), and in the y-axis direction, i.e., orthogonal to the roll direction (cross machine direction, CD or CMD). This results in very good values ​​for maximum tensile force and maximum tensile elongation according to DIN ISO 9073-3. This applies both in the dry and, especially, in the wet state.

[0048] The nonwovens and molded articles according to the invention exhibit only low shrinkage compared to products made from polylactic acid monocomponent fibers.

[0049] The nonwovens and molded bodies have good air permeability.

[0050] The following information on multi-component fibers a) and further fibers b) applies equally to the nonwovens according to the invention, the process according to the invention for producing a molded article and the molded articles according to the invention.

[0051] In the context of the invention, the term "multicomponent fiber" refers to fibers consisting of at least two polymer components. A specific embodiment is bicomponent fibers. At least two of the polymer components (in the case of bicomponent fibers, the two polymer components) differ in at least one property. Each polymer component can be formed from a single polymer or a mixture of polymers.

[0052] In a suitable embodiment, a polymer component of the multi-component fiber can comprise PLA and at least one polymer different from it. Suitable polymers different from PLA are the polymers described below as component b), to which reference is made here in their entirety. These include, for example, polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. The PLA-containing components of the multi-component fibers preferably contain at least one polymer different from PLA in an amount of at most 10 wt.%, more preferably at most 5 wt.%, in particular at most 1 wt.%, based on the total weight of the polymers forming the polymer component. In a specific embodiment, the PLA-containing components of the multi-component fibers are free of further polymers different from PLA.

[0053] The multicomponent fibers according to the invention comprise at least two polylactic acid (PLA) components, with the polylactic acid components preferably differing in at least one of the following properties: melting point, melt flow index, glass transition temperature, degree of polymerization, or crystallinity. The melt flow index (MFI = Melt Flow Index or MFR = Melt Flow Rate) serves to characterize the flow behavior under specific pressure and temperature conditions and can be determined using a capillary rheometer according to DIN EN ISO 1133.

[0054] The glass transition temperature can be determined using DSC (differential scanning calorimetry) (DIN EN ISO 11357-1 to 3).

[0055] In particular, the polylactic acid components of the multicomponent fibers according to the invention differ in their melting point.

[0056] In addition, the PLA components may differ in at least one further property, preferably selected from the melt flow index, the glass transition temperature, the degree of polymerization, the crystallinity, the molecular weight, the content of D(-)-lactic acid, the presence and / or the amount of other polymers and combinations thereof.

[0057] The polymer components of multicomponent fibers are arranged in essentially constant, distinct zones across the fiber cross-section. The components can be arranged in any desired configuration, such as core-shell, side-by-side, cake, island-in-the-sea, etc.

[0058] In a specific embodiment, component a) comprises a core-shell bicomponent fiber having a polylactic acid core and a polylactic acid sheath (PLA / PLA bicomponent fiber). In an even more specific embodiment, component a) consists of a core-shell bicomponent fiber having a polylactic acid core and a polylactic acid sheath.

[0059] Preferably, the melting temperature of the sheath of the bicomponent fiber is at least 1°C, preferably at least 5°C, in particular at least 10°C, lower than the melting temperature of the core.

[0060] Component a) preferably comprises a core-sheath bicomponent fiber, wherein the core has a melting point in the range 120 to 250°C, preferably 140 to 220°C, in particular 160 to 200°C.

[0061] Component a) preferably comprises a core-sheath bicomponent fiber, wherein the sheath has a melting point in the range from 80 to 200°C, preferably 100 to 180°C, in particular 120 to 160°C.

[0062] The fiber composition used according to the invention preferably contains, as component a), fibers with a fineness in the range of 0.1 to 20 dtex, particularly preferably 1 to 3 dtex. Processes for producing PLA / PLA multicomponent fibers are known to those skilled in the art and are commercially available, e.g., the corresponding Trevira brands from Indorama Ventures Fibers Germany GmbH.

[0063] Other fibers b)

[0064] In a specific embodiment, the nonwoven fabric according to the invention contains a fiber composition comprising at least one further fiber b) different from a). In a further specific embodiment, in a process for producing a shaped body, a fiber composition is provided in step i) which comprises at least one further fiber b) different from a).

[0065] Suitable additional fibres b) are conventional (non-biodegradable or compostable) fibres, biodegradable and / or compostable fibres and mixtures thereof.

[0066] Suitable conventional fibers b) are selected from fibers made of polyolefins, such as polyethylene (PE), polypropylene (PP) and poly(ethylene / propylene) copolymers, polyesters, such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT), polyamide homo- and copolymers, polystyrene homo- and copolymers and mixtures (blends) of two or more than two of the aforementioned polymers.

[0067] The nonwoven fabric according to the invention preferably contains a fiber composition comprising at least one further biodegradable and / or compostable fiber b). Furthermore, in a process for producing a molded article, a fiber composition comprising at least one further fiber b) different from a) is preferably provided in step i).

[0068] Preferably, the biodegradable and / or compostable fiber b) is selected from man-made cellulose fibers, cellulose-containing natural fibers, polyvinyl alcohol fibers, thermoplastic starch fibers, fibers of natural polymers other than these, biodegradable and / or compostable polyester fibers, polyesteramide fibers and mixtures thereof.

[0069] In a specific embodiment, the biodegradable and / or compostable fiber b) is selected from man-made cellulose fibers, cellulose-containing natural fibers and mixtures thereof.

[0070] The air permeability of the final nonwoven fabric can be controlled by the choice of pulp fibers. Air permeability depends on the wood species and quality, the pulping method, and the processing. Other parameters for controlling the air permeability of the final nonwoven fabric include the length, diameter, shape of the fibers, and the density of the pulp.In particular, the biodegradable and / or compostable fiber b) is selected from regenerated cellulose fibers, fibers made from cotton, linen (flax), hemp, bamboo, soy, palm, coconut, wool, silk, chitin, chitosan, poly(ethylene succinate) (PES) fibers, poly(butylene succinate) (PBS) fibers, poly(ethylene adipate) (PEA) fibers, poly(butylene succinate-co-butylene adipate) (PBSA) fibers, polyhydroxyacetic acid (PGA) fibers, poly(butylene succinate-co-butylene sebacate) (PBsu-co-BSe) fibers, poly(butylene succinate-co-butylene adipate) (PBSu-co-Bad) fibers, poly(tetramethylene succinate) (PTMS)- Fibers, polycaprolactone (PCL) fibers, polypropriolactone (PPL) fibers, poly(3-hydroxybutyrate) (PHB) fibers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers, and mixtures thereof.

[0071] The term "man-made cellulose fibers" (industrially manufactured cellulose fibers) encompasses both non-derivatized cellulose fibers and derivatized cellulose fibers. To produce cellulose fibers, the solid cellulose, which is present in the form of pulp, must first be dissolved. For this purpose, the cellulose can be dissolved in a suitable solvent and subjected to fiber formation with re-solidification. These processes produce non-derivatized cellulose fibers, which are also referred to as regenerated cellulose fibers, meaning the resulting fibers still consist of cellulose. Regenerated cellulose fibers are a preferred version of man-made cellulose fibers.

[0072] Alternatively, the cellulose can be derivatized, e.g., by esterification with an organic or inorganic acid, thus converting it into a more soluble form and then processing it into fibers. Organic carboxylic acids, especially acetic acid, propionic acid, butyric acid, and mixtures thereof, are preferably used for esterification. Derivatized cellulose fibers can contain a cellulose ester whose ester groups are derived from a single carboxylic acid, a cellulose mixed ester whose ester groups are derived from two or more carboxylic acids, and any mixtures thereof. Cellulose acetates are preferably used for fiber formation.

[0073] The nonwoven fabric according to the invention preferably contains a fiber composition comprising regenerated cellulose fibers as a further biodegradable and / or compostable fiber b). Furthermore, in a process for producing a molded article, a fiber composition comprising regenerated cellulose fibers as a further biodegradable and / or compostable fiber b) is preferably provided in step i). A specific embodiment is regenerated cellulose fibers produced by a direct solvent process using a tertiary amine oxide, specifically N-methylmorpholine N-oxide, as the solvent. Regenerated cellulose fibers produced in this way bear the generic name Lyocell.

[0074] Polyethylene succinate can be obtained by reacting succinic acid with 1,2-ethanediol (ethylene glycol). Polybutylene succinate can be obtained by reacting succinic acid with 1,4-butanediol. The starting materials (succinic acid and 1,4-butanediol) can be produced from both fossil fuels and glucose.

[0075] Polycaprolactone is formed by ring-opening polymerization of s-caprolactone.

[0076] Polypropriolactone is formed by ring-opening polymerization of propriolactone. Propriolactone, used as a starting material, can be produced by carbonylation of ethylene oxide.

[0077] Polyhydroxyacetic acid, also called polyglycolic acid (PGA), can be produced by anionic polymerization of glycolide, the dimer of hydroxyacetic acid.

[0078] A special form of aliphatic polyesters are polyhydroxyalkanoates, such as poly(3-hydroxybutyrate), poly(4-hydroxybutyrate) (PHB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). These are advantageously not only biodegradable and / or compostable, but also available from renewable (non-fossil) sources. Poly(3-hydroxybutyrate) (PHB) is formed by various bacteria through the fermentation of carbohydrates with a controlled nutrient supply. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) can also be produced by fermentation from glucose and propionic acid.

[0079] In the context of the invention, the term aliphatic-aromatic copolyester (AAC) refers to a polyester that incorporates at least one aromatic dicarboxylic acid, at least one aliphatic diol, and at least one further aliphatic component. The further aliphatic component is preferably selected from aliphatic dicarboxylic acids, hydroxycarboxylic acids, lactones, and mixtures thereof. In contrast to polyesters composed of at least one aromatic dicarboxylic acid and at least one aliphatic diol, such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), aliphatic-aromatic copolyesters (AAC) are generally biodegradable and / or compostable.

[0080] The aliphatic-aromatic copolyesters (AAC) are preferably selected from copolyesters of 1,4-butanediol, terephthalic acid, and adipic acid (BTA), copolyesters of 1,4-butanediol, terephthalic acid, and succinic acid, and copolyesters of 1,4-butanediol, terephthalic acid, isophthalic acid, succinic acid, and lactic acid (PBSTIL). Also suitable are blends of aliphatic-aromatic polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene isophthalate (PEIP), and glycol-modified polyethylene terephthalate (PETG) with at least one of the aforementioned aliphatic polyesters. PETG is obtained by esterifying terephthalic acid with ethylene glycol and 1,4-cyclohexanedimethanol (CHDM).

[0081] Preferably, the fibers b) comprise at least one polyvinyl alcohol or consist of at least one polyvinyl alcohol. In the context of the invention, polyvinyl alcohol (PVOH) refers to partially or fully saponified (hydrolyzed) polyvinyl acetates (PVA). Partially saponified polyvinyl acetates are obtained by incomplete hydrolysis of polyvinyl acetates, ie, the partially saponified polymer contains both ester groups and hydroxyl groups.

[0082] Preferably, the fibers b) comprise or consist of at least one thermoplastic starch. Thermoplastic starch (TPS) is a thermoplastic biopolymer produced by subjecting a substantially anhydrous starch starting material to a thermo-mechanical treatment, e.g., in an extruder. For production, a native starch or a starch derivative with a water content of no more than 5% can be homogenized in an extrusion process with a plasticizer that lowers the melting temperature of the starch, and melted by applying mechanical energy and heat. Thermoplastic starch is substantially free of crystalline components and does not recrystallize.

[0083] Suitable plasticizers include, for example, glycerol, glycerol acetate, sorbitol, aliphatic polyesters, aliphatic-aromatic copolyesters, polyesteramides, polyesterurethanes, polyalkylene oxides, and mixtures thereof. The plasticizer is preferably selected from biodegradable and / or compostable polymers. Specifically, at least one biodegradable and / or compostable polymer selected from aliphatic polyesters, aliphatic-aromatic copolyesters, polyesteramides, and mixtures thereof is used as the plasticizer.

[0084] Preferably, the starch material used to produce the thermoplastic starch is selected from native starches, oxidized starches, starch ethers, starch esters, cationically modified starches and mixtures thereof.

[0085] Depending on the type of oxidizing agent and the oxidation conditions, oxidized starches exhibit different degrees of oxidation, degrees of degradation, and regioselectivities of the resulting oxidation products. In addition to oxidation products with carboxyl functions, those with aldehyde functions, such as dialdehyde starch, are also considered oxidized starches.

[0086] Preferably, the fibers b) comprise at least one cellulose-containing natural fiber. The cellulose-containing natural fibers are preferably selected from cotton, linen (flax), hemp, bamboo, soy, palm, coconut, and mixtures thereof.

[0087] Preferably, the fibers b) comprise at least one natural polymer or consist of at least one natural polymer. The natural polymers are preferably selected from chitin, chitosan, plant proteins, keratin, and mixtures thereof. Keratin is a collective term for various water-insoluble, animal fiber proteins. Preferred keratins suitable for fiber production are wool and silk. Preferably, the fibers b) comprise at least one polyesteramide or consist of at least one polyesteramide. Suitable polyesteramides are the BAK polyesteramides, which are biodegradable and / or compostable. A special embodiment is polyesteramides that contain incorporated aliphatic ester units and aliphatic amide units. Thermoplastically processable and biodegradable aliphatic polyesteramides are described, for example, in EP 0641817 A2.

[0088] The fiber composition used according to the invention preferably contains, as component b), fibers having a fineness in the range from 0.1 to 30 dtex, particularly preferably 1 to 8 dtex.

[0089] The nonwoven fabric according to the invention preferably contains, based on the total weight of the nonwoven fabric, a mixture of a) 10 to 100 wt.% of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in melting point, b) 90 to 0 wt.% of at least one biodegradable fiber different from a).

[0090] Furthermore, in a process for producing a shaped body, a fiber composition is preferably provided in step i) which consists of a mixture of a) 10 to 100 wt.% of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in melting point, b) 90 to 0 wt.% of at least one biodegradable fiber different from a).

[0091] In a specific embodiment, the nonwoven fabric according to the invention contains, based on the total weight of the nonwoven fabric, a mixture of a) 10 to 90 wt.% of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in melting point, b) 90 to 10 wt.% of at least one biodegradable fiber different from a).

[0092] Specifically, in a process for producing a shaped body, in step i) a fiber composition is provided which consists of a mixture of a) 10 to 90 wt.% of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in melting point, b) 90 to 10 wt.% of at least one biodegradable fiber different from a).

[0093] Specifically, the nonwoven fabric according to the invention has at least one of the following properties: a maximum tensile strength dry, in the machine direction (MD) in the range of 5 to 100 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength wet, in machine direction (MD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2, a maximum tensile strength dry, cross to the machine direction (CD) in the range of 5 to 100 N / 5cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength wet, cross to the machine direction (CD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , an air permeability of 100 I rrn 2 s -1 up to 5000 I rrr 2 s -1 measured according to EN ISO 9237:1995 at 1 mbar on a nonwoven fabric with a basis weight of 30 g / m 2 , a shrinkage of the nonwoven fabric in the longitudinal direction (MD) in the range of 1% to 50% and in the transverse direction (CD) in the range of 0.1% to 30%, measured after heating to 135°C for 30 seconds on a nonwoven fabric with a basis weight of 30 g / m 2 , a shrinkage of the multicomponent fiber in the range of 0.1% to 30% measured at 125°C for 5 min.

[0094] Process for producing a shaped body

[0095] The invention further provides a process for producing a shaped body, in which i) a fiber composition is provided which a) comprises at least one multi-component fiber comprising at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally comprises at least one further biodegradable and / or compostable fiber b), ii) the fiber composition provided in step i) is subjected to a wet-laying process to produce a nonwoven fabric, iii) the nonwoven fabric is subjected to a thermal joining step by welding.

[0096] With regard to the fiber composition provided in step i), reference is made in full to the above information on suitable and preferred fibers a) and b).

[0097] In step ii) of the process according to the invention, the fiber composition provided in step i) is subjected to a wet-laying process to produce a nonwoven fabric. In wet-laying production, water is used to form fibers into a sheet-like structure, the so-called wet-laid web. Methods and devices for producing wet-laid nonwovens are known in principle to those skilled in the art. Wet-laid web production is generally based on the dewatering of a fiber suspension and subsequent drying. This principle is described, for example, in DE-OS-2655136. The fibers suspended in the water are passed over a sieve and dewatered, with the fibers being deposited on the sieve. This process is called sheet formation. The nonwoven fabric obtained after sheet formation still contains significant amounts of water. Further dewatering can be achieved, for example, by suction, e.g., using vacuum suction cups.The resulting product is generally still a loose composite of fibers, which is subjected to one or more further processing steps to obtain a nonwoven in the form of a fiber composite with the desired internal strength. These include known processes for bonding nonwovens, e.g., by hydroentanglement, needling, etc., as described in Fuchs, Albrecht, Nonwovens: Raw Materials, Production, Application, Properties, Testing, 2nd completely revised edition (2012), WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. The PLA / PLA fibers used in the invention are also suitable as binding fibers for chemically bonding the nonwoven.

[0098] If desired, fibres b) which are suitable as binding fibres for chemical nonwoven bonding can also be used in the fibre mixture.

[0099] The fibers of the fiber composition provided in step i) preferably have a length in the range of 0.5 to 50.0 mm, particularly preferably 1.0 to 30.0 mm. Specifically, fibers with a length of at most 30.0 mm, in particular at most 20.0 mm, are used. Fibers of this length are particularly suitable for use in a wet-laid nonwoven process. In the wet-laid nonwoven process, fibers with a length of up to 22 mm are preferably suspended in water in step ii), and the water-fiber dispersion is then deposited.

[0100] In step iii) of the process according to the invention, the nonwoven fabric obtained in step ii) is subjected to a thermal joining step by welding. In principle, conventional methods and devices for joining thermally weldable nonwoven fabrics are suitable for step iii). The nonwoven fabrics to be joined are placed on top of one another in the region of the desired joining point and, at elevated temperature and optionally elevated pressure, are at least partially converted into a thermoplastically deformable and thus weldable state and joined.

[0101] Suitable equipment for use in step iii) includes standard welding and sealing devices, fusing presses, multi-layer presses, etc. It is also possible to weld nonwovens in specific desired areas using calenders with structured rollers. This allows spot or strip-shaped welds to be applied, especially to large-format two- or multi-layer nonwovens.

[0102] Preferably, the treatment in step iii) is carried out at a surface pressure in the range of 0.3 to 30.0 MPa (3 to 300 bar or 0.3 to 30.0 N / mm 2 ), particularly preferably from 0.5 to 15.0 MPa.

[0103] When using calenders in step iii), the line pressure is preferably 3 to 500 N / mm, particularly preferably 5 to 100 N / mm. Calendering in step iii) is preferably carried out at a speed of 0.05 m / min to 30 m / min.

[0104] The treatment temperature and treatment time in step iii) can be selected depending on the melting point of the PLA components and, if present, any other binding fibers. For example, the treatment temperature and treatment time can be selected so that, in a multi-component fiber, only one or some of the components are plasticized. In a special embodiment, the treatment temperature and treatment time in step iii) are selected so that only the sheath component of a core-sheath bicomponent fiber is plasticized.

[0105] The treatment in step iii) is preferably carried out at a temperature in the range from 50 to 300°C, particularly preferably from 80 to 280°C, in particular from 100 to 250°C.

[0106] Preferably, the treatment in step iii) is carried out in a press over a period of 0.05 seconds to 5 minutes, preferably from 0.1 seconds to 1 minute.

[0107] The treatment in step iii) is preferably carried out in a calender over a period of time from greater than 0 seconds to 8 seconds, preferably from 0.01 seconds to 5 seconds. The invention further provides a shaped body obtainable by a process as described above.

[0108] Another object of the invention is the use of a nonwoven fabric as defined above for plant cultivation and agriculture, in particular as a container for the cultivation and growing of plants, for covering the soil, for protecting plants from cold and heat, for pollination bags, for protecting harvested goods, as a protective nonwoven fabric for plant transport and shipping, for protecting straw and hay bales and as a plant substrate for soilless plant cultivation, for the production of textile articles, for the thermal and / or acoustic insulation of buildings, vehicles, aircraft, ships, technical installations and household appliances, for filtration applications, packaging, dehumidification bags, hygiene products, personal care products, medical products, cleaning products in the household and I&L sector and products for home furnishing.

[0109] The nonwovens according to the invention and molded articles produced therefrom are particularly suitable as containers for plants, in particular as cultivation containers

[0110] The invention also relates to a method for producing containers for natural materials, preferably for plants, comprising the steps:

[0111] A) Providing a nonwoven fabric as previously defined

[0112] B) continuously forming the nonwoven fabric from A) into a continuous container by bringing the side edges of the nonwoven fabric into contact and joining the side edges,

[0113] C) cutting the continuous container into predetermined lengths, thereby obtaining separate plant containers, or wherein the continuous container is perforated substantially perpendicular to the longitudinal direction of the continuous container at predetermined intervals, thereby enabling separate plant containers to be separated from the continuous container.

[0114] PREFERRED EMBODIMENTS OF THE INVENTION

[0115] 1. A nonwoven fabric containing a fiber composition comprising a) at least one multicomponent fiber comprising at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally at least one further fiber different from a). Nonwoven fabric according to embodiment 1, wherein component a) comprises a core-shell bicomponent fiber having a polylactic acid core and a polylactic acid sheath. Nonwoven fabric according to embodiment 2, wherein the polylactic acid core and the polylactic acid sheath additionally differ in at least one of the following properties: melt flow index, glass transition temperature, degree of polymerization, or crystallinity.Nonwoven fabric according to embodiment 2 or 3, which has at least one of the following properties: the melting temperature of the sheath of the bicomponent fiber is at least 1°C, preferably at least 5°C, in particular at least 10°C, lower than the melting temperature of the core, the core has a melting point in the range from 120 to 250°C, preferably from 140 to 220°C, in particular from 160 to 200°C, the sheath has a melting point in the range from 80 to 200°C, preferably 100 to 180°C, in particular 120 to 160°C.Nonwoven fabric according to one of embodiments 1 to 4, wherein the fiber composition comprises at least one further fiber b) selected from fibers made of polyolefins, polyesters, polyamide homo- and copolymers, polystyrene homo- and copolymers and mixtures of two or more than two of the aforementioned polymers, in particular selected from polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, polytrimethylene terephthalate fibers, polybutylene terephthalate fibers, polyamide fibers and mixtures thereof.Nonwoven fabric according to one of embodiments 1 to 4, wherein the fiber composition comprises at least one further biodegradable and / or compostable fiber b), preferably selected from man-made cellulose fibers, cellulose-containing natural fibers, polyvinyl alcohol fibers, thermoplastic starch fibers, fibers of natural polymers different therefrom, biodegradable and / or compostable polyester fibers, polyesteramide fibers and mixtures thereof, in particular selected from man-made cellulose fibers, cellulose-containing natural fibers and mixtures thereof.Nonwoven fabric according to any one of embodiments 1 to 4 and 6, wherein the fiber composition comprises at least one further biodegradable and / or compostable fiber b), selected from viscose fibers, lyocell fibers, fibers made of cotton, linen (flax), hemp, bamboo, soy, palm, coconut, wool, silk, chitin, chitosan, poly(ethylene succinate) (PES) fibers, poly(butylene succinate) (PBS) fibers, poly(ethylene adipate) (PEA) fibers, poly(butylene succinate-co-butylene adipate) (PBSA) fibers, polyhydroxyacetic acid (PGA) fibers, poly(butylene succinate-co-butylene sebacate) (PBsu-co-BSe) fibers, poly(butylene succinate-co-butylene adipate) (PBSu-co-Bad) fibers, poly(tetramethylene succinate) (PTMS) fibers, polycaprolactone (PCL) fibers, polypropriolactone (PPL) fibers, poly(3-hydroxybutyrate) (PHB) fibers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers, and mixtures thereof.Nonwoven fabric according to one of the preceding embodiments, which is a wet-fiber nonwoven fabric. Nonwoven fabric according to one of the preceding embodiments, comprising, based on the total weight of the nonwoven fabric, a mixture of a) 10 to 100 wt. %, especially 10 to 90 wt. % of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in their melting point, b) 90 to 0 wt. %, especially 90 to 10 wt. %, of at least one biodegradable and / or compostable fiber different from a). Nonwoven fabric according to one of the preceding embodiments, which has at least one of the following properties: a maximum tensile strength dry, in the machine direction (MD) in the range of 5 to 100 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m. 2, a maximum tensile strength wet, in machine direction (MD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength dry, cross to the machine direction (CD) in the range of 5 to 100 N / 5cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength wet, cross to the machine direction (CD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , an air permeability of 100 I rrn 2 s -1 up to 5000 I rrr 2 s -1 measured according to EN ISO 9237:1995 at 1 mbar on a nonwoven fabric with a basis weight of 30 g / m 2, a shrinkage of the nonwoven fabric in the longitudinal direction (MD) in the range of 1% to 50% and in the transverse direction (CD) in the range of 0.1% to 30%, measured after heating to 135°C for 30 seconds on a nonwoven fabric with a basis weight of 30 g / m 2, a shrinkage of the multi-component fiber in the range of 0.1% to 30% measured at 125°C for 5 min. Process for producing a shaped body, in which i) a fiber composition is provided which a) comprises at least one multi-component fiber which comprises at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in their melting point, b) optionally comprises at least one further biodegradable and / or compostable fiber b), ii) the fiber composition provided in step i) is subjected to a wet-laying process to produce a nonwoven fabric, iii) the nonwoven fabric is subjected to a thermal joining step by welding. Process according to embodiment 11, wherein in the wet-laying process in step ii) fibers of up to 30 mm fiber length, preferably of up to 22 mm fiber length, are suspended in water and the water-fiber dispersion is then deposited.Shaped articles obtainable by a process as defined in embodiment 11 or 12. Use of a nonwoven fabric as defined in any one of embodiments 1 to 10 for plant cultivation and agriculture, in particular as a container for the propagation and cultivation of plants, for covering the soil, for protecting plants from cold and heat, for pollination bags, for protecting harvested goods, as a protective nonwoven fabric for plant transport and shipping, for protecting straw and hay bales, and as a plant substrate for soilless plant cultivation, for the production of textile articles, for the thermal and / or acoustic insulation of buildings, vehicles, aircraft, ships, technical systems, and household appliances, for filtration applications, packaging, dehumidification bags, hygiene products, personal care products, medical devices, cleaning products in the household and I&L sectors, and home furnishing products.

[0116] 15. Container for plants, in particular a cultivation container, comprising or consisting of a shaped body as defined in embodiment 13 or obtainable by a method as defined in embodiment 11 or 12.

[0117] 16. Methods for producing containers for natural materials, preferably for plants, comprise the steps:

[0118] A) providing a nonwoven fabric as defined in any one of embodiments 1 to 10;

[0119] B) continuously forming the nonwoven fabric from i) into a continuous container by bringing the side edges of the nonwoven fabric into contact and joining the side edges,

[0120] C) cutting the continuous container into predetermined lengths, thereby obtaining separate plant containers, or wherein the continuous container is perforated substantially perpendicular to the longitudinal direction of the continuous container at predetermined intervals, thereby enabling separate plant containers to be separated from the continuous container.

[0121] The invention is illustrated by the following examples, without being limited thereto.

[0122] EXAMPLES

[0123] In the following, nonwovens were used that were produced on a technical scale from short-cut fibers on a wet-laid nonwovens machine. At a fiber concentration of 0.3 wt.%, various batches, each 6530 m long and 2140 mm wide, were produced at a web forming speed of 100 m / min. The target basis weight was 25 or 30 g / m. 2These so-called production samples have a fiber orientation and are characterized by the machine direction (MD) and the cross-machine direction (CD).

[0124] Second, nonwovens were used, which were deposited on a sheet former on a laboratory scale from a fiber dispersion. These so-called laboratory samples exhibit no fiber orientation. For nonwoven formation on a laboratory scale, PLA / PLA bicomponent fibers and cellulose were weighed, dispersed in water in a Thermomix, deposited on a sheet former, and then dried on a dryer with a stenter frame at 135°C, with a 50% air flow at 0.50 m / min. -1 dried.

[0125] Different measurement methods were used to determine the properties of the production samples and the laboratory samples.

[0126] I.) Measurement methods

[0127] The thickness of the nonwovens in mm was determined according to EN ISO 9073-2:1996 "Determination of thickness of textile fabrics." The measurement was performed at a pressure of 0.00125 MPa (12.5 mbar) with a punch diameter of 35.7 mm. The average value of six measurements was determined.

[0128] The determination of the area-related mass (basis weight, grammage) in g / m 2 was carried out according to EN 29073-1:1992. The sample size for production samples was 200 x 250 mm, with the samples being punched out. For laboratory samples, the basis weight is determined using DIN A4 samples (297 mm x 210 mm).

[0129] The measurement of air permeability (gas permeability perpendicular to the material plane in I m -2 s' 1) was carried out according to EN ISO 9237:1995 to determine the air permeability of textile fabrics. The air permeability was measured at 1 mbar. The mean value of six measurements was determined. The results are shown in Table 1.

[0130] The determination of the ultimate tensile force (TDF) in Newtons and the ultimate tensile elongation (TDE) in percent was carried out on laboratory samples according to DIN 53857-2:1979-09. Test specimens measuring 157 mm x 50 mm were punched from the nonwovens according to the invention and the reference nonwovens. For laboratory samples, no distinction is made between (TDF) and (CD), and the same test procedure is used for dry and wet conditions.

[0131] For production samples, the HZK and HZD were determined according to EN 29073-3:1992 on test specimens measuring 200 mm x 50 mm. The tensile force / elongation behavior was measured in the roll direction (MD) and the counter-roll direction (CD), both dry and wet, i.e., four measurements were performed (MD, dry), (CD, dry), (MD, wet), and (CD, wet). For each individual measurement, four samples were punched, three of which were measured, and an average value was calculated (one sample served as a reference sample).

[0132] To determine the thermal dimensional change (shrinkage) of laboratory samples, it is determined how the area of ​​the nonwoven fabric deposited on the sheet former changes from the initial value (0.2 m 2 ) is reduced by the drying process, ie the difference in area before and after drying.

[0133] II.) Nonwoven fabric formation The nonwovens were produced according to the procedures described above for the production of laboratory samples and production samples with the following specifications for nonwovens 1 and 2.

[0134] Nonwoven fabric 1)

[0135] Basis weight: 30 g / m 2

[0136] Fiber material:

[0137] 70% of a bicomponent fiber (core / sheath: PLA / PLA) 2.2 dtex, length 8 mm 30% pure cellulose

[0138] Nonwoven fabric 2)

[0139] Basis weight 30 g / m 2

[0140] Fiber material:

[0141] 60% of a bicomponent fiber (core / sheath: PLA / PLA) 2.2 dtex, length 8 mm 10% pure cellulose

[0142] 30% viscose fiber

[0143] The following Table 1 shows the measured values ​​for nonwoven fabric 1.

[0144] Table 1

[0145] (MD) = in machine direction, (CD) = perpendicular to the machine direction

[0146] III.) Storage tests

[0147] The following storage tests are designed to assess the biodegradability of the nonwovens used. They also aim to determine a correlation between storage at room temperature and storage at elevated temperatures (40°C).

[0148] For these tests, production samples of the two above-mentioned binder-free nonwovens 1) and 2) were used to manufacture plant containers (plant sleeves).

[0149] Sample preparation:

[0150] Sample size: 157 mm X 50 mm, sampling using a punch

[0151] Punching direction: Perpendicular to the material direction (CMD)

[0152] The material is cut into narrow strips to produce planting sleeves.

[0153] These are then formed into a tube in the longitudinal direction and welded. During this manufacturing process, the material is subjected primarily to transverse stress.

[0154] Welding:

[0155] Kopp sealing device SGPE 3200

[0156] Temperature sealing bar top: 170°C,

[0157] Temperature sealing bar below: without heating (room temperature),

[0158] Time: 0.2 s, Pressure: 75 N

[0159] The weld is placed as close as possible to the end of the superimposed sample.

[0160] Fill:

[0161] Four samples each were placed in a 10 x 10 x 4 cm polystyrene tray. 25 g of moist potting soil (approximately 35% moisture content) were placed on a laboratory scale into the circularly shaped nonwoven fabric (plant sleeve). The soil was compacted with light pressure using a stamp.

[0162] Watering: 30 g of tap water was carefully poured over each sample, ensuring the samples were very moist, but no water remained in the tray. After approximately 15 minutes, the samples were checked again in the trays and, if necessary, water was discarded.

[0163] Packing:

[0164] Two trays each were packed in a 20 x 32 cm LDPE bag with a zip closure.

[0165] Storage:

[0166] The samples were stored under the specified storage conditions, and a sample was taken from the trays every week. The samples were cut open close to the seam, the soil was roughly removed, and the strips were allowed to dry. From the dry strips, the remaining soil was carefully removed with a brush if necessary.

[0167] Measurement:

[0168] The maximum tensile strength of the samples was determined according to EN 29073-3:1992, as described above. Four samples were tested per day. The decrease in the maximum tensile strength serves as a measure of decomposition.

[0169] Test series 1:

[0170] Nonwoven fabric 1, storage at 20°C

[0171] Table A

[0172] Test series 2:

[0173] Nonwoven fabric 1 , storage at 40°C

[0174] Table B

[0175] Test series 3:

[0176] Nonwoven fabric 2, storage at 20°C Table C

[0177] Test series 4

[0178] Nonwoven fabric 2, storage at 40°C

[0179] Table D

[0180] IV. Welding tests

[0181] A Kopp SGPE 3200 sealing device was used for sealing. The upper sealing bar was heated to the temperatures specified below, while the lower sealing bar was unheated. The sealing time was 0.2 s, the pressure was 75 N, and the sample width was 50 mm. To form the seal, two sheets of the nonwoven fabric, as defined above, each with a basis weight of 30 g / m², were used. 2 laid on top of each other with a slight overlap and then welded.

[0182] Temperature variation: tear resistance

[0183] Welding at 175°C fixed temperature

Claims

Patent claims 1. A process for producing a shaped body, comprising i) providing a fiber composition which a) comprises at least one multi-component fiber comprising at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally comprises at least one further fiber different from a), ii) subjecting the fiber composition provided in step i) to a wet-laying process to produce a nonwoven fabric, iii) subjecting the nonwoven fabric to a thermal joining step by welding.

2. The method according to claim 1, wherein in the wet-laid nonwoven process in step ii) fibers of up to 30 mm fiber length, preferably of up to 22 mm fiber length, are suspended in water and then the water-fiber dispersion is deposited.

3. The method according to claim 1 or 2, wherein component a) comprises a core-sheath bicomponent fiber having a polylactic acid core and a polylactic acid sheath.

4. The process according to claim 3, wherein the polylactic acid core and the polylactic acid shell additionally differ in at least one of the following properties: melt flow index, glass transition temperature, degree of polymerization or crystallinity.

5. The method according to claim 3 or 4, wherein the core-sheath bicomponent fiber has at least one of the following properties: the melting temperature of the sheath of the bicomponent fiber is at least 1°C, preferably at least 5°C, in particular at least 10°C, lower than the melting temperature of the core, the core has a melting point in the range from 120 to 250°C, preferably from 140 to 220°C, in particular from 160 to 200°C, the sheath has a melting point in the range from 80 to 200°C, preferably 100 to 180°C, in particular 120 to 160°C.

6. The method according to any one of the preceding claims, wherein the fiber composition comprises at least one further fiber b) selected from fibers made of polyolefins, polyesters, polyamide homo- and copolymers, polystyrene homo- and copolymers and mixtures of two or more than two of the aforementioned polymers, in particular selected from polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, polytrimethylene terephthalate fibers, polybutylene terephthalate fibers, polyamide fibers and mixtures thereof.

7. The method according to any one of claims 1 to 6, wherein the fiber composition comprises at least one further fiber b) selected from biodegradable and / or compostable fibers b).

8. The method according to claim 7, wherein the fiber composition comprises at least one further biodegradable and / or compostable fiber b) selected from man-made cellulose fibers, cellulose-containing natural fibers, polyvinyl alcohol fibers, thermoplastic starch fibers, fibers of natural polymers other than these, biodegradable and / or compostable polyester fibers, polyesteramide fibers and mixtures thereof, in particular selected from man-made cellulose fibers, cellulose-containing natural fibers and mixtures thereof.

9. The method according to claim 7 or 8, wherein the fiber composition comprises at least one further biodegradable and / or compostable fiber b), selected from viscose fibers, lyocell fibers, fibers made of cotton, linen (flax), hemp, bamboo, soy, palm, coconut, wool, silk, chitin, chitosan, poly(ethylene succinate) (PES) fibers, poly(butylene succinate) (PBS) fibers, poly(ethylene adipate) (PEA) fibers, poly(butylene succinate-co-butylene adipate) (PBSA) fibers, polyhydroxyacetic acid (PGA) fibers, poly(butylene succinate-co-butylene sebacate) (PBsu-co-BSe) fibers, poly(butylene succinate-co-butylene adipate) (PBSu-co-Bad) fibers, poly(tetramethylene succinate) (PTMS) fibers, polycaprolactone (PCL) fibers, polypropriolactone (PPL) fibers, poly(3-hydroxybutyrate) (PHB) fibers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers, and mixtures thereof.

10. Shaped body obtainable by a process as defined in any one of claims 1 to 9.

11. Nonwoven fabric containing a fiber composition comprising a) at least one multi-component fiber comprising at least two polylactic acid components (PLA components), wherein the polylactic acid components differ in melting point, b) optionally at least one fiber b) different from a).

12. Nonwoven fabric according to claim 11, wherein component a) comprises a core-sheath bicomponent fiber as defined in any one of claims 3 to 5.

13. Nonwoven fabric according to claim 11 or 12, wherein the fiber composition comprises at least one further fiber b) as defined in any one of claims 6 to 9.

14. Nonwoven fabric according to one of claims 11 to 13, containing, based on the total weight of the nonwoven fabric, a mixture of a) 10 to 100% by weight, especially 10 to 90% by weight, of at least one bicomponent fiber, wherein both components comprise polylactic acid (PLA) and the two phases differ in their melting point, b) 90 to 0% by weight, especially 90 to 10% by weight, of at least one biodegradable and / or compostable fiber different from a).

15. Nonwoven fabric according to one of claims 11 to 14, which has at least one of the following properties: a maximum tensile strength dry, in the machine direction (MD) in the range of 5 to 100 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength wet, in machine direction (MD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2, a maximum tensile strength dry, cross to the machine direction (CD) in the range of 5 to 100 N / 5cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , a maximum tensile strength wet, cross to the machine direction (CD) in the range of 3 to 80 N / 5 cm, measured according to EN 29073-3:1992 on a nonwoven fabric with a basis weight of 30 g / m 2 , an air permeability of 100 I rrn 2 s -1 up to 5000 I rrr 2 s -1 measured according to EN ISO 9237:1995 at 1 mbar on a nonwoven fabric with a basis weight of 30 g / m 2 , a shrinkage of the nonwoven fabric in the longitudinal direction (MD) in the range of 1% to 50% and in the transverse direction (CD) in the range of 0.1% to 30%, measured after heating to 135°C for 30 seconds on a nonwoven fabric with a basis weight of 30 g / m 2 , a shrinkage of the multicomponent fiber in the range of 0.1% to 30% measured at 125°C for 5 min.

16. Use of a nonwoven fabric as defined in any one of claims 11 to 15 for plant cultivation and agriculture, in particular as containers for the propagation and cultivation of plants, for covering the soil, for protecting plants from cold and heat, for pollination bags, for protecting harvested goods, as protective fleece for plant transport and shipping, for protecting straw and hay bales and as plant substrate for soilless plant cultivation, for the manufacture of textile articles, for the thermal and / or acoustic insulation of buildings, vehicles, aircraft, ships, technical installations and household appliances, for filtration applications, packaging, dehumidification bags, hygiene products, personal care products, medical devices, cleaning products in the household and I&L sector and home furnishing products.

17. Container for plants, in particular a cultivation container, comprising or consisting of a shaped body as defined in claim 10 or obtainable by a process as defined in any one of claims 1 to 9.

18. Methods for producing containers for natural materials, preferably for plants, comprise the steps: A) providing a nonwoven fabric as defined in any one of claims 11 to 15; B) continuously forming the nonwoven fabric from A) into a continuous container by bringing the side edges of the nonwoven fabric into contact and joining the side edges, C) cutting the continuous container into predetermined lengths, thereby obtaining separate plant containers, or wherein the continuous container is perforated substantially perpendicular to the longitudinal direction of the continuous container at predetermined intervals, thereby enabling separate plant containers to be separated from the continuous container.

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