Sheet containing thermoplastic styrenic elastomer, method for production thereof and use thereof

Abstract

A sheet comprising a support layer and a cover layer, where the cover layer contains a thermoplastic polyurethane as component (a) and a thermoplastic styrenic elastomer as component (b), where the support layer and the cover layer are directly bonded to each other, and where the support layer is a fabric layer or a fabric layer covered with a polyvinyl chloride layer; a sewn product obtainable by sewing the sheet material; a method of making the sheet; the invention also relates to the use of the sheet or sewn product as artificial leather, in particular as covering material in the interior of a vehicle.

Description

Technical Field

[0001] The present invention relates to a sheet material comprising a support layer and a cover layer, wherein the cover layer contains thermoplastic polyurethane (TPU) and thermoplastic styrene elastomer (TPS), a method for preparing the sheet material, and use of the sheet material as a surface material of artificial leather such as for vehicle interior. Background Art

[0002] EP 3 533 601 A1 discloses a composite structure comprising a low-density foam layer, a textile layer and a thermoplastic cover layer comprising a polyolefin or polyvinyl chloride and optionally a thermoplastic elastomer. The composite structure exhibits good tear properties and tactile feel and is improved in terms of wrinkle formation and handling during processing, in particular during sewing.

[0003] CN 210151469 U discloses an artificial leather comprising a fabric layer and a covering layer of a thermoplastic styrene elastomer, which is suitable for preparing sewn products.

[0004] US 2010 / 0055358 A1 discloses a composition comprising a thermoplastic and a thermoplastic styrene elastomer and a laminate structure comprising a layer formed from the composition.

[0005] Problems to be solved by the present invention

[0006] The prior art discloses a multilayer composite structure which, on the one hand, provides a desired balance of softness and flexibility to achieve good touch and handling during processing such as sewing; on the other hand, it facilitates the production of sheets and enhances the adhesion between sheet layers.

[0007] The technical problem to be solved by the present invention is to provide a new type of structure which can achieve a balance of desired performances with a small number of layers. Summary of the invention

[0008] This application covers the following aspects.

[0009] [1] A sheet comprising a support layer and a cover layer, wherein the cover layer contains a thermoplastic polyurethane as component (a) and a thermoplastic styrene elastomer as component (b), wherein the support layer and the cover layer are directly bonded to each other, and wherein the support layer is a fabric layer or a fabric layer covered with a polyvinyl chloride (PVC) layer.

[0010] [1-1] The sheet according to aspect [1], wherein the fabric layer as the support layer partially interpenetrates with the cover layer.

[0011] [1-2] A sheet material according to one of the aforementioned aspects, which is suitable for preparing a sewn product obtainable by sewing the sheet material, and is preferably suitable for preparing a sewn product by the following steps: folding the sheet material, placing the A sides or B sides of two parts of the sheet material together to form a contact area, and sewing the two parts of the sheet material in the contact area.

[0012] [1-3] A combination of aspects [1] and [1-2] is preferred.

[0013] [1-4] The sheet material according to any one of the preceding aspects, wherein the cover layer consists of a single layer or two sub-layers.

[0014] [1-5] The sheet according to any of the preceding aspects, wherein the content of each of component (a) and component (b) in the cover layer is at least 20% by mass, preferably at least 30% by mass.

[0015] [1-6] The sheet material according to one of the preceding aspects, wherein the cover layer is coated with a paint layer having a thickness of less than 30 μm.

[0016] [1-7] The sheet material according to one of the preceding aspects, wherein the sheet material has a suture tear-off force of at least 40 N according to DIN EN ISO 23910.

[0017] [1-8] A combination of aspects [1-3] and [1-7] is preferred.

[0018] [1-9] The sheet material according to one of the preceding aspects, wherein the sheet material preferably shows no damage and no change after 1,000,001 flexure cycles in a test according to DIN 53 351.

[0019] [1-10] The sheet according to any one of the aforementioned aspects, wherein the light transmittance is 1% to 100%, preferably 1% to 50%, and more preferably 5% to 50%.

[0020] [1-11] A sheet material according to one of the aforementioned aspects, wherein the sheet material can be folded to form a double-layer structure, in which the two B surfaces of the sheet material are stacked on each other and contact each other at the folded edges, and the double-layer structure can be unfolded to its original state, wherein preferably, the sheet material does not show visible damage or changes at the folded edges after folding and unfolding.

[0021] [1-12] The sheet material according to any of the preceding aspects, wherein the PVC layer covers the B-side surface of the fabric layer, or more preferably covers the A-side surface of the fabric layer.

[0022] [1-13] The sheet material according to one of the preceding aspects, wherein the PVC layer is composed of a plurality of PVC sub-layers, wherein the PVC sub-layer in contact with the fabric layer is an adhesive layer.

[0023] [1-14] The sheet material according to one of the preceding aspects comprises a composite material structure consisting of a fabric layer, a PVC layer and a covering layer in the order shown.

[0024] [2] The sheet material according to any of the preceding aspects, wherein the fabric layer contains or consists of one or more fibers selected from the group consisting of polyester, polypropylene, polyamide and natural fibers such as cotton.

[0025] [3] The sheet according to any one of the preceding aspects, wherein component (a) is aromatic.

[0026] [3-1] A sheet according to any one of the preceding aspects, wherein each urethane unit of component (a) contains an aromatic group. [3-2] A sheet according to any one of the preceding aspects, wherein component (a) is derived from an aromatic diisocyanate. [3-3] A combination of aspects [3-1] and [1-3] is preferred. [3-4] A combination of aspects [3-1] and [1-8] is more preferred. [3-5] A sheet according to any one of the preceding aspects, wherein the cover layer consists of two sublayers, and component (a) of the A-side sublayer is aromatic, wherein the A-side sublayer preferably also contains components (b) and (c).

[0027] [4] The sheet according to any one of the preceding aspects, wherein component (b) is polystyrene-block-poly(ethylene-butylene)-block-polystyrene.

[0028] [5] The sheet according to any one of the preceding aspects, wherein the cover layer contains a compatibilizer as component (c).

[0029] [6] The sheet according to any one of the preceding aspects, wherein component (c) is a copolymer containing a polyurethane block and a styrenic polymer block.

[0030] [6-1] The sheet according to aspect [6], wherein the styrene-based polymer block is a hydrogenated styrene-diene polymer.

[0031] [7] A sheet according to any one of the preceding aspects, wherein the support layer is a fabric layer and the cover layer contains a thermoplastic aromatic polyurethane as component (a), a thermoplastic elastomer based on a styrene block copolymer as component (b) and a compatibilizer as component (c).

[0032] [7-1] A combination of aspects [7] and [1-3] is preferred. [7-2] A combination of aspects [7] and [1-8] is more preferred. [7-3] A combination of aspects [7] and [3-1] is more preferred.

[0033] [8] A sheet according to any one of the preceding aspects, wherein the covering layer contains 20 to 80 parts by mass of component (a), 15 to 80 parts by mass of component (b) and 1 to 20 parts by mass of component (c), wherein the total amount of components (a) to (c) is 100 parts by mass.

[0034] [8-1] The sheet according to any one of the preceding aspects, wherein components (a) to (c) account for more than 80% by mass, preferably more than 90% by mass of the covering layer.

[0035] [9] The sheet material according to one of the preceding aspects, wherein the cover layer has a Shore A hardness of less than 50 according to DIN 53505.

[0036] [9-1] The sheet according to any of the preceding aspects, wherein the sheet has a Shore A hardness of 35 to 50 according to DIN 53505. [9-2] The combination of aspects [9] and [1-3] is preferred. [9-3] The combination of aspects [9] and [1-8] is more preferred. [9-4] The combination of aspects [9] and [3-3] is more preferred. [9-5] The combination of aspects [9-4] and [7] is particularly preferred.

[0037]

[10] The sheet material according to any of the preceding aspects, wherein the support layer is a fabric layer having a thickness of 0.05 to 1.0 mm, preferably 50 to 300 μm, and the cover layer has a thickness of 0.1 to 1.0 mm.

[0038]

[11] A sewn product obtainable by sewing the sheet material according to any one of the preceding aspects.

[0039]

[12] A method for preparing a sheet according to one of the preceding aspects, comprising: (i) providing a molten covering layer raw material containing components (a), (b) and optionally (c), (ii) applying the molten covering layer raw material to a support layer, and (iii) solidifying the composition to obtain a sheet.

[0040]

[13] A method according to aspect

[12] , wherein step (i) comprises: (i-1) providing a masterbatch containing a pigment as component (d); and (i-2) mixing the masterbatch with components (a) and (b) and optionally (c) to obtain a molten covering layer raw material.

[0041] [13-1] The method according to aspect

[13] , wherein the mixing and melting in step (i-2) are performed using an extruder.

[0042] [13-2] A method according to any one of aspects

[12] to [13-1], wherein step (ii) comprises applying molten cover material to a support layer, such as a fabric layer, such that the molten cover material only partially interpenetrates the support layer.

[0043] [13-3] A method for producing a sewn product, comprising sewing the sheet material according to any one of [1] to

[11] .

[0044] [13-4] The method according to aspect [13-3], comprising: folding a sheet, placing the B sides such as a support layer together to form a contact area, and sewing the two parts of the sheet in the contact area.

[0045]

[14] Use of the sheet material according to any one of aspects [1] to

[10] or the sewn product according to aspect

[11] as artificial leather.

[0046] [14-1] Use of the sheet material according to any one of [1] to

[10] in a cutting and sewing process.

[0047]

[15] Use of the sheet material according to any one of aspects [1] to

[10] or the sewn product according to aspect

[11] as a covering material in a vehicle interior

[0048] [15-1] Preferably, the use of aspect

[15] is for interior decoration, such as seats.

[0049] Invention Advantages

[0050] The sheet material according to the invention exhibits lower wrinkling when bent. This makes it easier to handle, in particular to sew. The manufacturing costs can be reduced by reducing the number of layers and adopting a one-step production in a one-step lamination process.

[0051] The combination of TPS and TPU reduces the hardness and elastic modulus, making it easier for the needle to penetrate the sheet, suitable for cutting and sewing applications. The use of TPS is a low-cost alternative to traditional materials. The addition of TPS improves adhesion to the substrate and the thermal stability of the product.

[0052] The fabric layer further enhances the desired properties. Combining the fabric layer with a thinner cover layer can reduce the weight of the sheet while maintaining the desired properties.

[0053] The sheet can be advantageously used as a coating material in a vehicle interior. DETAILED DESCRIPTION

[0054] The sheet of the present invention may be composed of or contain the support layer and the covering layer described herein. The support layer is arranged on the B side of the sheet, and the covering layer is arranged on the A side of the sheet. Herein, the terms "A side" and "B side" may refer to the sheet as a whole or to a single layer. The layers may be directly laminated, that is, the A side of the support layer is in direct contact with the B side of the covering layer without any material, such as an adhesive, being arranged therebetween; or indirectly laminated, that is, other layers or adhesive layers are arranged therebetween. The covering layer may optionally be coated with a paint layer. The sheet itself is a layered structure. The B side of the support layer may also be provided with additional layers or structures.

[0055] Herein, unless expressly stated otherwise, the terms "sheet", "support layer" and "cover layer" respectively refer to "sheet according to the present invention", "support layer contained in the sheet according to the present invention" and "cover layer contained in the sheet according to the present invention".

[0056] The sheet material comprises a composite material structure (i) or (ii) or (iii), the composite material structure consisting of the following layers in the specified order: (i) a fabric layer and a cover layer; (ii) a fabric layer, a PVC layer and a cover layer; (iii) a PVC layer, a fabric layer and a cover layer. Preferably, the sheet material comprises a composite material structure (i) or (ii). The sheet material may contain at least one additional layer on the A side or the B side of the composite material structure.

[0057] In the case where the fabric layer is directly bonded to the covering layer as (a part of) the supporting layer, since the fabric layer contains voids, these layers may interpenetrate. Interpenetrating structure is referred to as composite (compound) structure in this article. This compound structure is composed of a part of the supporting layer and a part of the covering layer in the thickness direction. In each case, the term "a part" refers to that each layer is not included in the compound structure in the entire thickness direction of each layer. In other words, complete interpenetration is excluded, and both the covering layer and the supporting layer have non-interpenetrating layer parts in the thickness direction. As a result, the supporting layer of the fabric layer, for example, is not exposed at the A side (that is, the covering layer surface) of the sheet, and the covering layer is not exposed at the B side (that is, the supporting layer surface) of the sheet.

[0058] In case of using the PVC sublayer as an adhesive to bond the support layer and the cover layer, the adhesive only partially penetrates the support layer, so that the support layer has a non-interpenetrating layer portion in the thickness direction.

[0059] The cover layer may contain a structural element on its B side (i.e. between the cover layer and the support layer). The structural element may have optical properties. The structural element may be an opaque or colored pattern that forms a graphic design, image or logo for decorative or indication purposes. For example, the structural element may be a very thin printed structure visible through the cover layer. Examples of applying the pattern are inkjet printing, screen printing, laser printing or laser etching. The cover layer and the support layer are directly bonded to each other in the area without the structural element.

[0060] Preferably, the sheet is suitable for preparing a sewn product obtainable by sewing at least two sheets or two parts of the same sheet. The sewn product can be prepared by folding the sheet, placing the two A-side or B-side parts of the sheet together, and sewing the two parts of the sheet in the contact area. In order for the sheet according to the present invention to have the desired properties, such as the performance of being easy to process during sewing, the sheet should not be too hard. In order to be suitable for sewing, the sheet also needs to have a suitable suture tear-off force. According to DIN EN ISO 23910, the suture tear-off force is preferably at least 40N. In one embodiment, the sheet is suitable both as a tearable coating for an airbag cover without material weakening and for preparing a sewn product obtainable by sewing at least two layers of a sheet.

[0061] In one embodiment, the sheet is formed only by thermal bonding, i.e., by using a molten cover layer composition or at least partially molten cover layer. Preferably, the support layer does not melt at the temperature used in the thermal bonding process. For example, the polypropylene fibers in the support layer can be partially melted and thermally bonded. On the other hand, the polyester fibers can not melt and are bonded to the cover layer by thermomechanical bonding, i.e., only by the molten cover layer material penetrating into the fabric layer. In the case where the support layer is connected to the cover layer only by thermal bonding, the connection is reversible, and the support layer and the cover layer can be separated from each other by melting at least a portion of the cover layer at room temperature or by heating, and at least a portion of the cover layer is part of the chemical structure. In another embodiment, the sheet is treated with radiation or electron beams from the support layer B side to form chemical bonds in the chemical structure, thereby enhancing the bonding of the support layer to the cover layer. In this case, the connection between the support layer and the cover layer is irreversible, i.e., the layers cannot be separated by at least partially melting the cover layer.

[0062] The sheet material according to the present invention can be opaque or translucent. Generally, when light is emitted from the same light source and impinges on the structure, a translucent structure allows more visible light to be transmitted than an opaque structure. In this article, the meaning of the term "translucency" covers the meaning of "transparency". Generally, transparency is a physical property that allows light to pass through a material without being scattered. Translucency is a superset of transparency, allowing light to pass through and allowing scattering. In other words, a translucent medium allows the transmission of light, while a transparent medium allows not only the transmission of light but also the formation of images. Transparent materials appear transparent. Since the transmittance value is affected by factors such as absorption, scattering, and reflection, the transmittance values ​​of different components of the sheet material may vary depending on the type of light source, the composition and thickness of each layer. The transmittance is also different for different wavelength ranges. The transmittance of the layer structure described in this application (i.e., a single layer or any composite structure) was determined as follows: Equipment: Datacolor, Model 850; Lamp: Xenon. The total transmittance was measured according to the user guide provided by the manufacturer. A white patch (e.g. The sensor is used as an optical standard for transmission calibration and measurement. The white patch is placed at the front aperture plate. The sample to be measured is placed between the sphere opening and the sensor. The wavelength λ of the maximum transmittance peak of the sample is max The transmittance [%] of the sample is defined as 100% × (in the case of a layer structure at λ max (measured transmittance value at λ in the absence of a layer structure) / (measured transmittance value at λ in the absence of a layer structure) max ). Light transmittance refers to the transmittance of light emitted at a position facing the B surface of the sheet or layer and detected at a position facing the A surface of the sheet or layer. If all layers are translucent, the light transmittance of the sheet refers to the entire sheet. The light transmittance of the sheet may be 1% to 100%, 1% to 90%, 1% to 50% or 5% to 50%, preferably 1% to 30%, more preferably 2% to 20%. Low light transmittances such as 1% to 50% may be advantageous for hidden-until-lit applications. In order to achieve the hidden-until-lit feature of hiding the elements arranged on the B surface of the cover layer when no light source is activated, at λ max The light transmittance of the film is preferably 1% to 50%, more preferably 1% to 30%, still more preferably 2% to 20% or 5% to 10%. In the case where the hidden lighting characteristic is not desired, at λ max The light transmittance of the film may be 10% to 90%, preferably 20% to 80%, and more preferably 30% to 70%.

[0063] The sheet may contain additives, such as ultraviolet (UV) stabilizers, pigments, heat stabilizers and flame retardants. These additives may be contained in the cover layer and the optional paint layer in particular. Generally, low concentrations of additives are preferred to achieve extremely high light transmittance. The pigment may be selected from carbon black, organic red, organic yellow, phthalocyanine blue and titanium white. In order to provide a sheet with uniform color and high transparency, it is preferred to use a small particle size pigment to reduce light scattering. The particle size of the pigment is preferably less than 10 μm, more preferably less than 1 μm, and further preferably less than 100 nm. Heat stabilizers help to maintain the properties of the polymer at high temperatures. Various heat stabilizers can be used, such as metal salts (for stabilizing PVC), organometallic compounds, non-metallic organic stabilizers, organic phosphites and epoxy resins. Organic phosphites protect polymers during the manufacturing process. Phenolic antioxidants protect polymers during the service life of the polymer. Phenolic antioxidants are free radical scavengers that prevent thermal degradation of polymers. When used in combination with phosphites, thioethers and light stabilizers, their effectiveness is enhanced. Other examples of antioxidants are sterically hindered phenols such as butylated hydroxytoluene (2,6-di-tert-butyl-4-methylphenol, BHT), butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ) and gallic acid esters. In particular, halogenated polymers such as polyvinyl chloride (PVC) may require the use of heat stabilizers.

[0064] UV stabilizers as additives can achieve the purpose of maintaining the desired light transmittance after exposure to UV radiation. The wavelength range of UV radiation is between 280 and 400 nm. Polymers are sensitive to certain wavelengths of UV radiation. For example, aromatic polyurethane is a polymer that is sensitive to UV. Suitable UV stabilizers can be ultraviolet absorbers and hindered amine light stabilizers (HALS). Rutile titanium dioxide is effective in the range of 300 to 400 nm, but is not effective in the very short wavelength UVB range below 315 nanometers. Hydroxybenzophenone and hydroxyphenylbenzotriazole have the advantage of being particularly suitable for transparent applications. Other UV absorbers include oxalic dianilide for polyamides, benzophenone, benzotriazole and hydroxyphenyltriazine for polyvinyl chloride. Hindered amine light stabilizers (HALS) have a 2,2,6,6-tetramethylpiperidine ring structure. HALS are particularly effective in polyolefins and polyurethanes. Any of these compounds can be used in combination. Some of these combinations have synergistic effects. For example, benzotriazole is often used in combination with HALS.

[0065] In the present invention, the terms "comprises / comprising", "includes", "containing" and "having" are open terms used to indicate the presence of features, steps, layers and / or components, but do not exclude the presence or addition of one or more other features, steps, layers, components and / or combinations thereof. The method steps, processes and operations herein should not be construed as having to be performed in the particular order discussed or shown, unless explicitly indicated as an order of execution. It should also be understood that additional steps may be employed.

[0066] In the context of this specification, whenever it is mentioned that each composition or layer is based on a certain material, it should be understood that each material forms the main component of the composition or layer, wherein other components may also be present in small amounts. In an embodiment, the term "based on" a certain material means that the content of the material is greater than 50% by mass, preferably greater than 90% by mass, and more preferably greater than 95% by mass.

[0067] As used herein, the singular forms "a," "an," and "the" may be intended to include the plural forms, unless the context clearly indicates otherwise. For example, components are often described in the singular, such as "a" component or "containing a" component. Unless otherwise indicated, such singular formulations are intended to include more than one of the specified component.

[0068] The term "and / or" includes any and all combinations of one or more of the relevant listed items. Percentages (%) are % by mass unless expressly stated otherwise. Unless otherwise stated, the standards and specifications mentioned refer to the latest versions available at the time of filing this application.

[0069] Support layer

[0070] The support layer is a fabric layer or a fabric layer covered with a PVC layer. In the support layer of the fabric layer covered with a PVC layer, the fabric layer and the PVC layer are directly bonded to each other. The support layer is preferably flexible and thin. Preferably, the support layer is composed of a fabric layer. Examples of fabric layers are knitted fabrics, woven fabrics, nonwoven fabrics, fiberglass fabrics, spunlace fabrics or spacer fabrics. Knitted fabrics are flexible materials formed by interweaving yarns or threads, and the yarns or threads are made by spinning raw fibers into long and twisted fibers. The fabric is not a dense structure, and it contains a large number of gaps that are usually filled with air. The density of the fabric layer is preferably 100 to 300 kg / m 3 .

[0071] The fabric layer of the support layer may contain or consist of one or more fibers selected from the following group: polyester, polypropylene, polyamide, cotton and natural fibers.

[0072] The support layer can consist of a single layer, for example a fabric layer forming a composite structure with the cover layer. Since the cover layer can also consist of a single layer, the sheet can consist of only two layers, namely the support layer and the cover layer, and optionally a lacquer layer.

[0073] In addition to the fabric layer, the support layer may also contain other layers. For example, the support layer may be a fabric layer bonded to a polyvinyl chloride layer on its A side or B side. The PVC layer may be a single layer or composed of two or more polyvinyl chloride sublayers. The A side and / or B side PVC sublayer may have adhesive properties and may be referred to as an adhesive layer. The PVC may be a dense layer or a foam layer or a combination thereof. The support layer may comprise a fabric layer with a thickness of 0.3 to 5 mm, a thickness of 0.5 to 10 mm and a density preferably of 30 to 300 kg / m 3 The sheet material comprises a foam layer of 0.3 to 2.5 mm, and an optional fabric layer having a thickness of 0.3 to 2.5 mm, arranged in this order, wherein each fabric layer is preferably directly bonded to the foam layer. The foam layer may have adhesive properties so that it can be firmly bonded to the A-side or B-side fabric without adding other adhesives. Direct bonding excludes additional layers or additional adhesive layers between the fabric layer and the foam layer. Therefore, the sheet material may contain several layers without any additional adhesive layer.

[0074] Side B of the support layer may contain additional layers, such as a foam layer or a polyvinyl chloride layer, and / or functional elements, such as a touch sensor. In the case of functional elements, the sheet may be translucent and side B of the cover layer or side B of the support layer may contain opaque areas.

[0075] Covering

[0076] The covering layer consists of components (a) and (b) or contains components (a) and (b). The thickness of the covering layer is preferably 100 μm to 1000 μm, more preferably 200 μm to 300 μm. The density of the covering layer is preferably at least 800 kg / m 3 , more preferably higher than 850kg / m 3 . Preferably, the cover layer is dense. The cover layer may consist of one or more layers. Preferably, the cover layer consists of a single layer or two sublayers. In the case of containing two or more sublayers, the components herein, in particular components (a) to (c), may be contained in one or more or all sublayers. For example, the aromatic component (a) may be contained only in or at least in the upper (i.e., A-side) sublayer of a cover layer consisting of two sublayers.

[0077] The cover layer preferably has elastic and / or thermoplastic properties, more preferably both elastic and thermoplastic properties. The elastic properties and other physical properties of the film layer (such as melting point and softness) can be determined by its elastomer content. The cover layer is flexible and preferably shows no damage and changes after 500,000 flexing cycles, more preferably after 1,000,000 flexing cycles, in a test according to DIN 53 351.

[0078] The covering layer may contain conventional additives, such as plasticizers, stabilizers, anti-aging agents (e.g. antioxidants), fillers and pigments (e.g. silica, TiO2, CaCO3, Mg(OH)2, carbon black, mica, kaolin, clay, coal powder, lignin, talc, BaSO4, Al(OH)3, ZnO and MgO), flame retardants (e.g. antimony trioxide or zinc hydroxystannate), waxes, colorants, compatibilizers and other auxiliary substances (e.g. viscosity aids, adhesion promoters, etc.). Examples of UV stabilizers are those mentioned above.

[0079] The cover layer of the sheet may have a texture, i.e. a three-dimensional structured surface covered with paint on the A side. The texture may be present only in the cover layer, or in both the cover layer and the paint layer. In this case, the sheet structure can be used as artificial leather. The texture can be formed by known methods such as embossing. The depth of the texture is less than the thickness of the cover layer. The texture can be produced using conventional methods. It is preferred that the texture is applied to the artificial leather surface by an embossing roller while applying pressure and temperature after painting.

[0080] The cover layer can be translucent. The optical properties of a polymer are determined by its structure. Generally, amorphous polymers provide transparency, while crystalline polymers provide opacity, especially in thicker products such as injection molded final products. Crystallinity reduces transparency by causing refraction, reflection and scattering of light at the boundary between the crystalline region and the amorphous region. The light transmittance of semi-crystalline polymers can be improved by additive technology. The crystalline structure is usually very ordered and therefore has high strength and rigidity. On the other hand, amorphous polymers are characterized by relatively low heat resistance, poor toughness at low temperatures and low dimensional stability. Therefore, it is preferred that the polymer is not completely amorphous and has a certain degree of crystallinity. In the present invention, the desired balance of optical properties and other physical properties (such as flexibility) can be achieved by adjusting the crystallinity.

[0081] The covering layer may be coated with a paint layer. The paint may be made of conventional materials. The thickness of the paint layer is preferably 1 to 30 μm, more preferably 3 to 10 μm. The paint layer is applied directly to the top of the covering layer (i.e., the A-side surface) as a finishing layer and provides protection against chemical agents, physical damage (such as scratches or abrasions) and ultraviolet radiation. The paint layer can also further reduce surface adhesion. Conventional paints for artificial leather for vehicle interiors, such as paint layers based on silicone-containing aliphatic polyurethanes, can be used. The paint layer is generally composed of one or more layers of transparent paint layers, preferably no more than four layers. The paint layer is preferably elastic. The properties of the paint layer (such as elasticity and translucency) can be adjusted to match the corresponding properties of the covering layer.

[0082] Component (a)

[0083] The covering layer contains a thermoplastic polyurethane (TPU) as component (a). Component (a) does not contain styrene units and is therefore different from component (b). TPU is a thermoplastic elastomer comprising a linear block copolymer consisting of a hard segment and a soft segment. Polyurethane is prepared from a polyisocyanate (such as a diisocyanate) and a polyol (such as a diol). The isocyanate may be aliphatic or aromatic, and the polyol may be aliphatic or aromatic. The aliphatic group may be linear or branched and may have 1 to 10 carbon atoms, in particular 1 to 6 carbon atoms. It may be methyl, ethyl, propyl, butyl, pentyl and / or hexyl. The alicyclic group may be based on a cyclopropyl, cyclobutyl, cyclopentyl, dicyclohexylmethane, cyclohexyl and / or isophorone group. Heterocyclic groups include furfuryl. The polyol may be a polymer having a molecular weight of 200 to 12,000, in particular 250 to 2,000. Examples of polyols are polyester polyols, polyether polyols, polythioether polyols, polycarbonate polyols, hydroxyl-containing aliphatic polyacetals, hydroxyl-containing aliphatic polycarbonates, or mixtures of at least two of the above polyols. Thermoplastic polyurethanes (TPUs) may contain groups derived from compounds containing reactive groups other than hydroxyl groups, such as compounds containing thiol groups or amine groups.

[0084] Preferably, the TPU contains aromatic groups and is therefore an aromatic TPU. For example, the TPU can be prepared using aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and naphthalene diisocyanate (NDI). The content of aromatic groups in the TPU may be greater than 3% by mass or even greater than 5% by mass. Aromatic TPUs are harder than aliphatic TPUs due to the presence of aromatic rings resulting in higher hardness and tensile strength. Therefore, aromatic TPUs make the cover harder and less suitable for cutting and sewing applications. The use of TPS makes the cover more flexible and can compensate for the effects of aromatic TPUs.

[0085] The cover layer may contain a compatibilizer as component (c). The compatibilizer enables or facilitates the preparation of a homogeneous blend of components (a) and (b). Preferably, component (c) is a copolymer containing a polyurethane block and a styrenic polymer block, wherein the styrenic polymer block may be a polymer of hydrogenated styrene-diene.

[0086] Component (b)

[0087] The cover layer contains a thermoplastic styrene elastomer (TPS) as component (b). Component (b) does not contain urethane units and is therefore different from component (a). TPS is a styrene block copolymer, preferably a styrene-butadiene-styrene block copolymer (SBS) or a styrene-ethylene-butylene-styrene block copolymer (SEBS), i.e. a polystyrene-block-poly(ethylene-butylene)-block-polystyrene. TPS is a thermoplastic elastomer (TPE), which is defined as an elastomer that exhibits thermoplastic behavior. The term "thermoplastic" refers to a polymer or polymer composition that exhibits thermoplastic properties, particularly thermal reversibility. TPS has a soft elastomer component and a hard component.

[0088] Generally, the general classification of TPE is as follows (named according to ISO 18064): styrene block copolymer (TPS), thermoplastic polyolefin elastomer (TPO), thermoplastic vulcanizate (TPV), thermoplastic polyurethane (TPU), thermoplastic copolyester (TPC), melt-processed rubber and thermoplastic polyamide (TPA). In addition to TPS, the cover layer may also contain one or more of the above TPEs except TPS.

[0089] The content of TPS in the cover layer is preferably at least 50%. The total content of thermoplastic polymers in the cover layer, i.e. the total content of TPS, TPE other than TPS and other thermoplastic polymers other than TPS, is preferably at least 80%, more preferably at least 90%. Preferably, the polymers in the cover layer are all composed of thermoplastic polymers, and more preferably, account for at least 80% by mass, more preferably at least 90% by mass of the total mass of the cover layer. Preferably, the cover layer does not contain polyolefins.

[0090] Manufacturing method

[0091] The sheet according to the present invention can be prepared by a method comprising the following steps:

[0092] (i) providing a molten cover material containing components (a), (b) and optionally (c), (ii) applying the molten cover material to a support layer, and (iii) solidifying the composition to obtain a sheet.

[0093] The preparation method may start with a cover layer composition consisting of a thermoplastic elastomer and other components to be included in the final cover layer.

[0094] In step (i), the cover layer composition may be provided in the form of (A) particles (such as particles of the cover layer composition) or (B) a finished film comprising the cover layer composition.

[0095] In the case of (A), step (i) comprises melting the particles of the cover layer composition, preferably using an extruder. A masterbatch containing a pigment as component (d) and components (a), (b) and optionally (c) can be mixed to obtain a molten cover layer raw material. Preferably, a masterbatch is used to uniformly distribute the pigment in the cover layer. In the case of (B), step (i) comprises heating the film on at least one side to at least partially melt the cover layer composition contained in the film. A cover layer composition having a melting temperature lower than the melting temperature of the fabric layer of the support layer can be selected. Therefore, the molten cover layer composition penetrates into the hollow space of the support layer without melting the fibers of the support layer. In this case, the cover layer and the support layer can be separated from each other by heating. Alternatively, a cover layer composition having a melting temperature equal to or higher than the melting temperature of the support layer and capable of withstanding its temperature when in contact with the molten cover layer can be selected. Therefore, the molten cover layer composition at least partially melts the fibers of the support layer when penetrating into the hollow space. In this case, the cover layer and the support layer are more firmly bonded to each other.

[0096] In step (ii), for the case of (A), it is preferred to use an extruder to form the laminate. The molten cover layer composition can be extruded and applied to the support layer, or the molten cover layer composition can be extruded onto a carrier, and then the support layer is applied to the cover layer composition. In both cases, it is necessary to select appropriate cover layer composition, support layer and process conditions so that the cover layer and the support layer interpenetrate to a predetermined degree. If pressure is applied during the laminate forming process, the support layer is compressed, so that the molten cover layer composition can penetrate more easily and more deeply. As a result, the bonding force between the support layer and the cover layer is enhanced.

[0097] In the case of (B), step (ii) may include a step (ii-1) of forming a laminate of a film and a support layer and a step (ii-2) of embossing the other side of the film to form a texture structure, wherein steps (ii-1) and (ii-2) may be performed simultaneously. Step (ii) may be implemented by using two rollers. The laminate may be formed by laminating a portion of the molten surface of the film to the support layer while being conveyed through a narrow gap between the two rollers. The use of rollers with a defined gap width enables the preparation of a sheet with a compound structure of a defined thickness. The roller in contact with the cover layer may have a texture structure embossed on the surface of the cover layer. Therefore, the formation and embossing of the laminate may be performed in a single step.

[0098] Example

[0099] The cover layers were prepared as shown in Table 1.

[0100] Table 1

[0101]

[0102] Secant modulus was measured in machine direction (MD) and cross direction (CD) according to ISO 527 / 3. Heat aging was evaluated according to EN 20 105-A02.

[0103] The data show that the combination of thermoplastic polyurethane (TPU) and thermoplastic starch (TPS) in the cover layer has significant advantages. The product of Example 1 is improved in terms of scratch resistance, softness, low crystallinity, flexibility and heat aging performance.

[0104] Heat aging properties can be further improved by using a masterbatch and adding heat stabilizers.

[0105] The sheet material according to the present application, which comprises a cover layer coated on a fabric layer, shows improved properties of the cover layer and the fabric layer, and has additional benefits in terms of low wrinkling and good handling during processing (such as sewing).

Claims

1. A sheet material comprising a support layer and a cover layer, wherein the cover layer contains a thermoplastic polyurethane as component (a) and a thermoplastic styrene-based elastomer as component (b), wherein the support layer and the cover layer are directly bonded to each other, and wherein the support layer is a fabric layer or a fabric layer covered with a polyvinyl chloride layer.

2. The sheet material according to claim 1, wherein the fabric layer contains or consists of one or more fibers selected from the following group: Polyester, polypropylene, polyamide and natural fibers.

3. The sheet material according to any one of the preceding claims, wherein component (a) is aromatic.

4. The sheet material according to any one of the preceding claims, wherein component (b) is polystyrene-block-poly(ethylene-butylene)-block-polystyrene.

5. The sheet material according to claim 1, wherein the cover layer contains a compatibilizer as component (c).

6. The sheet material according to any one of the preceding claims, wherein component (c) is a copolymer comprising polyurethane blocks and styrenic polymer blocks.

7. The sheet material according to claim 1, wherein the support layer is a textile layer and the cover layer contains as component (a) a thermoplastic aromatic polyurethane, as component (b) a thermoplastic elastomer based on styrenic block copolymers and as component (c) a compatibilizer.

8. The sheet according to any one of the preceding claims, wherein the cover layer contains 20 to 80 parts by mass of component (a), 15 to 80 parts by mass of component (b) and 1 to 20 parts by mass of component (c), wherein the total amount of components (a) to (c) is 100 parts by mass. 9 . The sheet material according to claim 1 , wherein the cover layer has a Shore A hardness of less than 50 according to DIN 53505.

10. The sheet material according to any of the preceding claims, wherein the support layer is a textile layer having a thickness of 0.05 to 1.0 mm and the cover layer has a thickness of 0.1 to 1.0 mm.

11. A sewn product obtainable by sewing a sheet material according to any one of claims 1 to 10.

12. A method for preparing a sheet material according to any one of claims 1 to 10, comprising: (i) providing a molten cover material comprising components (a), (b) and optionally (c), (ii) applying the molten cover material to a support layer, and (iii) solidifying the composition to obtain the sheet.

13. The method of claim 12, wherein step (i) comprises: (i-1) a step of providing a masterbatch containing a pigment as component (d), and (i-2) a step of mixing the masterbatch with components (a) and (b) and optionally (c) to obtain the molten covering layer raw material.

14. Use of the sheet material according to any one of claims 1 to 10 or the sewn product according to claim 11 as artificial leather.

15. Use of a sheet material according to one of claims 1 to 10 or a sewn product according to claim 11 as a covering material in a vehicle interior.

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