Sheet containing thermoplastic elastomer, preparation method and application

Abstract

The invention relates to a sheet comprising a support layer made of a fabric, a cover layer on the support layer, and a composite structure wherein the cover layer contains a thermoplastic elastomer, and wherein the composite structure consists of a portion of the support layer and a portion of the cover layer interpenetrating one another, wherein the degree of interpenetration is defined as [(thickness of composite structure) / (thickness of capping layer)] x 100%, from 5% to 99%; a method of making the sheet; and the use of the sheet as a surface material in a vehicle interior.

Description

Technical Field

[0001] The present invention relates to a sheet material comprising a supporting layer, a covering layer and a composite structure, a method for preparing the sheet material, and use of the sheet material as a surface material such as artificial leather for vehicle decoration. Background Art

[0002] EP 3 766 687 A1 discloses a composite structure comprising a low-density foam layer and inner and outer layers of a thermoplastic dense cover layer. The composite structure is soft and elastic and exhibits good properties as an airbag cover, such as low tensile strength.

[0003] EP 3 533 601 A1 discloses a composite structure comprising a low-density foam layer, a textile layer and a thermoplastic cover layer, the thermoplastic cover layer comprising two sublayers. The composite structure exhibits good tear properties and tactile properties and is improved in terms of wrinkle formation and handling during processing, especially during sewing. The composite structure is produced by hot melt lamination.

[0004] EP 3 960 440 A1 discloses a composite structure comprising a textile layer arranged between a cover layer and a base layer, wherein the cover layer and the base layer penetrate completely into the textile layer and are thermally bonded to one another.

[0005] Problems to be solved by the present invention

[0006] The prior art discloses composite structures having several layers in order to provide a desired balance between properties in terms of softness and elasticity in order to achieve a good tactile feel and handling during processing, such as sewing, on the one hand, and facilitating the production of the composite structure on the other hand.

[0007] The problem underlying the present invention is to provide a new structure which achieves the desired balance of properties with fewer layers than prior art structures by using an improved manufacturing method. Summary of the invention

[0008] The problem underlying the present invention is solved by providing a sheet material according to the invention.

[0009] The present application covers the following preferred aspects.

[0010] [1] A sheet material comprising a support layer, a covering layer and a composite structure, wherein the support layer comprises a fabric layer, the covering layer is a dense layer comprising a thermoplastic elastomer and is arranged on the fabric layer of the support layer, and the composite structure is composed of a portion of the support layer and a portion of the covering layer interpenetrating each other, wherein the degree of interpenetration is defined as [(thickness of the composite structure) / (thickness of the covering layer)] x 100%, which is 5% to 99%, and the thickness of the covering layer is the thickness of the composite structure plus the thickness of the portion of the covering layer that is not part of the composite structure.

[0011] [1-1] The sheet according to aspect [1] is suitable for preparing a stitched product that can be obtained by stitching at least two layers of the sheet, preferably suitable for preparing a stitched product by folding the sheet, placing the supporting layers together and stitching two parts of the contact area of ​​the sheet.

[0012] [1-2] A sheet material according to any one of the preceding aspects, wherein when a cross section of the sheet material is observed under a microscope, an area density of the portion of the support layer that is part of the composite structure is at least 80% of an area density of the support layer that is not part of the composite structure.

[0013] [1-3] The sheet material according to any one of the preceding aspects, wherein the cover layer consists of a single composition, preferably a single layer.

[0014] [1-4] The sheet according to any one of the preceding aspects, wherein the cover layer comprises two or more layers, wherein the compositions of these layers are preferably different from each other.

[0015] [1-5] A sheet material according to any one of the preceding aspects, wherein the degree of interpenetration of the fabric layers is defined as [(thickness of the composite structure) / (thickness of the fabric layer)] x 100%, which is 10% to 90%, and the thickness of the fabric layer is the thickness of the composite structure plus the thickness of the portion of the fabric layer that is not part of the composite structure.

[0016] [1-6] The sheet according to a combination of aspects [1] and [1-5].

[0017] [1-7] The sheet material according to any one of the preceding aspects, wherein the light transmittance of the cover layer is 1% to 100%, preferably 1% to 50%, and more preferably 5% to 50%.

[0018] [1-8] The sheet material according to any one of the preceding aspects, wherein the support layer, in particular the fabric layer, has a light transmittance of 1% to 100%, preferably 1% to 50%, and more preferably 5% to 50%.

[0019] [1-9] The sheet material according to any one of the preceding aspects, wherein the light transmittance of the composite structure is 1% to 100%, preferably 1% to 50%, and more preferably 5% to 50%.

[0020] [1-10] The sheet according to any one of the aforementioned aspects, wherein the light transmittance of the sheet is 1% to 100%, preferably 1% to 50%, and more preferably 5% to 50%.

[0021] [1-11] The sheet according to a combination of aspects [1-6] and [1-7].

[0022] [1-12] The sheet according to a combination of aspects [1-6] and [1-10].

[0023] [1-13] The sheet material according to any one of the preceding aspects, wherein the support layer is a fabric layer, and a foam layer, preferably a polyolefin foam layer, is bonded to the bottom surface of the fabric layer directly or via an adhesive layer.

[0024] [2] The sheet material according to any one of the preceding aspects, wherein the degree of interpenetration of the cover layers and / or the interpenetration of the fabric layers is from 10% to 70%, preferably from 15% to 60%.

[0025] [3] The sheet according to any one of the preceding aspects, wherein the content of the thermoplastic elastomer in the cover layer composition is at least 50%.

[0026] [4] The sheet material according to any of the preceding aspects, wherein the cover layer composition has a Shore A hardness of less than 90, preferably less than 70, even more preferably less than 50 according to DIN 53505.

[0027] [4-1] The sheet according to any one of the preceding aspects, wherein the sheet has a Shore A hardness of 20 to 50 according to DIN 53505.

[0028] [4-2] The sheet according to a combination of aspects [4] and [4-1].

[0029] [5] A sheet material according to any one of the preceding aspects, wherein the thickness of the portion of the cover layer that is not part of the composite structure is at least 0.04 mm, preferably at least 0.2 mm.

[0030] [6] A sheet material according to any one of the preceding aspects, wherein the support layer comprises a fabric layer having a thickness of 0.3 to 5 mm; the cover layer has a thickness of 0.1 to 1.5 mm; and the composite structure has a thickness of 0.01 to 1.0 mm.

[0031] [6-1] The sheet material according to aspect [6], wherein the thickness of the fabric layer of the support layer is at least twice the thickness of the cover layer.

[0032] [6-2] The sheet material according to any one of the preceding aspects, wherein the cover layer has a thickness of 0.1 mm to 1.5 mm, and the composite structure has a thickness of 0.01 mm to 1.0 mm.

[0033] [6-3] A sheet according to aspect [6-2], wherein the thickness of the portion of the covering layer that is not part of the composite structure is at least 0.04 mm, the degree of interpenetration is 10 to 70%, and the thickness of the supporting layer, preferably the fabric layer of the supporting layer, is at least twice the thickness of the covering layer.

[0034] [7] A sheet according to any one of the preceding aspects, wherein the support layer comprises, in sequence, a fabric layer with a thickness of 0.3 to 5.0 mm, a foam layer with a thickness of 0.5 to 10 mm, and an optional fabric layer with a thickness of 0.3 to 2.5 mm, wherein each of the fabric layers is preferably directly bonded to the foam layer; or wherein the support layer comprises two fabric layers bonded to each other via an adhesive layer.

[0035] [8] A sheet material according to any one of the preceding aspects, wherein the fabric layer of the support layer comprises or consists of one or more fibers selected from the following group: polyester, polypropylene, polyamide, cotton or other natural fibers.

[0036] [8-1] The sheet according to aspect [8], wherein the fibers are polypropylene fibers and the cover layer is based on polypropylene.

[0037] [8-2] The sheet according to the combination of aspects [7] and [8-1], wherein the fabric layer is composed of polypropylene fibers.

[0038] [9] A sheet material according to any one of the preceding aspects, wherein the sheet material is obtainable by a method comprising thermal bonding or thermomechanical bonding of the cover layer and the support layer.

[0039] [9-1] A sheet according to aspect [9], wherein the composite structure is formed in a bonding step, wherein at least a portion of the covering layer composition or a film made of the covering layer composition is in a molten form and the support layer is in a non-molten form, or wherein at least a portion of the covering layer composition or a film made of the covering layer composition is in a molten form and at least a portion of the support layer is in a molten form.

[0040] [9-2] The sheet material according to aspect [9] or [9-1], wherein a method of bonding the cover layer and the support layer includes applying pressure and heat treatment in a single step.

[0041]

[10] The sheet material according to any one of the preceding aspects, wherein the sheet material has a tear propagation resistance of 10 to 50 N in the longitudinal direction and in the transverse direction according to DIN EN ISO 4674-1.

[0042]

[11] The sheet material according to any one of the preceding aspects, wherein the sheet material is artificial leather.

[0043] [11-1] A stitched product obtainable by stitching at least two layers of the sheet material according to any one of the preceding aspects.

[0044]

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

[11] or the stitched product according to aspect [11-1] as a surface material in a vehicle interior, preferably for use in a cutting and stitching process.

[0045]

[13] A method for preparing a sheet according to any one of aspects [1] to

[11] , the method comprising the following steps:

[0046] (a) providing a cover composition comprising a thermoplastic elastomer;

[0047] (b) at least partially melting the thermoplastic elastomer of the cover layer composition;

[0048] (c) forming a laminate of a cover layer composition comprising an at least partially molten thermoplastic elastomer and a support layer comprising a fabric layer such that the cover layer composition and the fabric layer of the support layer at least partially interpenetrate each other; and

[0049] (d) cooling the cover layer composition to obtain the sheet.

[0050] [13-1] The method according to aspect

[13] , wherein the step of embossing the sheet to form a textured structure on the cover layer is performed before, after, or simultaneously with the step of forming the laminate.

[0051]

[14] The method according to aspect

[13] , wherein the melting in step (b) and the laminate formation in step (c) are performed using an extruder.

[0052]

[15] A method according to aspect

[13] , wherein step (a) comprises providing the covering layer composition in the form of a film made of the covering layer composition, step (b) comprises heating the film on at least one side to at least partially melt the thermoplastic elastomer, and step (c) comprises step (c1) of forming a laminate by contacting the one side of the film with the support layer and step (c2) of forming a textured structure by embossing the other side of the film, wherein steps (c1) and (c2) are performed simultaneously, preferably by using a cylindrical member.

[0053] Advantages of the Invention

[0054] The sheet material according to the invention exhibits low wrinkle formation when bent. This makes handling easier and in particular facilitates sewing. The manufacturing costs can be reduced by reducing the number of layers and by facilitating production in a one-step lamination process. Another advantage is that the sheet material is easy to recycle when the materials of the various layers are selected from the same family of compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Shown is a cross section of the sheet of Example 1. The degree of interpenetration is 22%. Figure 2 Shown is a cross section of the sheet of Example 2. The degree of interpenetration is 29%. Figure 3 Shown is a cross section of the sheet of Example 3. The degree of interpenetration is 37%. Figure 4 Shown is a cross section of the sheet of Comparative Example 1. The degree of interpenetration is 0%. DETAILED DESCRIPTION

[0056] In the present invention, the terms "comprise", "include" and "have" are inclusive, thus specifying the presence of the features, steps and / or components, but not excluding the presence or addition of one or more other features, steps, components and / or groups thereof. The method steps, processes and operations described herein should not be construed as necessarily requiring them to be performed in the particular order discussed or shown, unless that particular order is explicitly identified as the order of execution. It should also be understood that additional steps may be employed.

[0057] Whenever it is mentioned in the context of this specification that a separate composition or layer is based on a certain material or made of a certain material, this should be interpreted as the corresponding material forming the main component of the composition or layer, wherein small amounts of other components may also be present. In various embodiments, the term "based on" a certain material or "made of a certain material" means that the content exceeds 50%, preferably 90%, and more preferably 95%.

[0058] As used herein, the singular forms "a", "an", and "the" may also be intended to include the plural forms, unless the context clearly indicates otherwise. For example, structural elements and components are often described in singular form, such as "a" component or "containing a" component. Unless otherwise indicated, such singular forms are intended to include more than one of the referred component or structural element.

[0059] The term "and / or" includes any and all combinations of one or more of the listed associated items. Unless otherwise expressly indicated, the percentage (%) of the component content is the mass percentage (mass %). Unless otherwise indicated, the standards and specifications mentioned refer to the latest version available at the time of filing this application.

[0060] Sheet

[0061] The sheet material according to the present invention comprises a support layer, a cover layer and a composite structure as essential components. The cover layer may optionally be coated with a lacquer layer. The sheet material itself is a layer structure. The plane of the sheet material layer is sometimes referred to as the "layer plane".

[0062] In the sheet of the present invention, the composite structure consists of a portion of the support layer and a portion of the cover layer. In each case, the term "a portion" means that the corresponding layer is not included in the composite structure in the entire thickness direction. In other words, complete interpenetration is excluded, and the cover layer and the support layer both have non-interpenetrating layer portions in the thickness direction. Therefore, the fabric layer is not exposed at the topmost surface of the sheet (i.e., the cover layer surface), and the cover layer is not exposed at the bottom surface of the sheet (i.e., the fabric layer surface).

[0063] Preferably, the sheet is suitable for preparing a stitched product that can be obtained by stitching at least two layers of the sheet. The stitched product can be prepared by folding the sheet, placing the support layers together and stitching the two parts of the sheet on the contact area. In order for the sheet according to the invention to have the desired properties, such as easy processing when stitching, the sheet must not be too hard. Therefore, the Shore A hardness of the sheet according to the invention is preferably less than 90, more preferably less than 50. For suitability for stitching, it is also important that the sheet has a suitable stitching tear resistance. According to DIN EN ISO 23910, the stitching tear resistance is preferably at least 40N.

[0064] In one embodiment, the sheet material is suitable both as a tearable coating for an airbag cover without material weakening and for producing a seamed product obtainable by seaming at least two layers of the sheet material.

[0065] 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 fabric layer of the support layer does not melt at the temperature used for thermal bonding. 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 can be bonded to the cover layer by thermomechanical bonding, i.e., only the molten cover layer material penetrates into the fabric layer. In the case where the support layer and the cover layer are connected only by thermal bonding, the connection is reversible, and the support layer and the cover layer can be separated from each other at room temperature or separated from each other by heating to melt at least the part of the cover layer that is part of the composite structure. In another embodiment, the connection of the support layer and the cover layer is strengthened by, for example, irradiating or electron beam treating the sheet from the underside of the support layer to form chemical bonds between the inside of the composite structure. In this case, the connection between the support layer and the cover layer is irreversible, i.e., these layers cannot be separated by at least partially melting the cover layer.

[0066] The support layer and the covering layer of the sheet can be characterized by their thickness. In the present invention, the thickness of the covering layer is defined as the thickness of the composite structure plus the thickness of the portion of the covering layer that is not part of the composite structure. Similarly, the thickness of the support layer is defined as the thickness of the composite structure plus the thickness of the portion of the supporting layer that is not part of the composite structure. As a result, the thickness of the sheet can be the sum of the thickness of the raw material support layer and the thickness of the raw material covering layer minus the thickness of the composite structure. In the present invention, the thickness of a layer or structure in a sheet can be determined by preparing a cross section perpendicular to the layer plane of the sheet and observing the cross section using a microscope. The thickness of a layer or structure is the average thickness obtained by determining the thickness over a range of at least 10 mm of the length of the layer or structure.

[0067] The sheeting according to the present invention may be opaque or translucent. Generally, a translucent structure allows more visible light to be transmitted than an opaque structure when light is emitted from the same light source and illuminates the structure.

[0068] In the present invention, the meaning of the term "translucency" covers the meaning of "transparency". Generally speaking, transparency is a physical property that allows light to pass through a material without being scattered. Translucency is an extended set of transparency and allows light to pass through and allows scattering. In other words, a translucent medium allows light transmission, while a transparent medium allows not only light transmission but also image formation. Transparent materials appear transparent. Since the value of transmittance is affected by absorption, scattering, reflection, etc., the exact transmittance values ​​of different components of a composite structure may vary depending on the type of light source, the composition and thickness of each layer. The transmittance of different wavelength ranges is also different.

[0069] The light transmittance of the layer structures described in this application, i.e. the individual layers 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 plate (e.g. The white plate is used as an optical standard for transmission calibration and measurement. The white plate is placed at the front aperture plate. The sample to be measured is placed between the sphere opening and the sensor. At the wavelength λ of the maximum transmittance peak of the sample max The transmittance [%] of a sample is defined as 100% x (in the presence of a layer structure at λ max Transmittance value measured at λ) / (transmittance value measured at λ in the absence of a layer structure max The light transmittance of a sheet is the transmittance value measured at the bottom surface of the sheet or layer. The light transmittance refers to the permeability of light emitted at a position facing the bottom surface of the sheet or layer and detected at a position facing the top surface of the sheet or layer. If all layers are translucent, the light transmittance of the sheet refers to the light transmittance of the entire sheet.

[0070] 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 transmittance, such as 1% to 50%, may be advantageous for hidden lighting applications.

[0071] Support layer

[0072] The support layer comprises a fabric layer. Preferably, the support layer consists of a fabric layer. Examples of fabric layers are knitted fabrics, woven fabrics, nonwoven fabrics, glass fiber fabrics, spunlace fabrics or spacer fabrics. Knitted fabrics are flexible materials made by creating double threaded yarns or strands, which are produced by spinning raw fibers into long twisted lengths. Spacer fabrics are flexible materials formed by two surface fabric layers, which are connected by spacer threads at a defined spacing. The fabric or textile is not dense, but contains a large volume ratio of hollow spaces that are usually filled with air. The density of the fabric layer is preferably 100 to 300 kg / m 3 .

[0073] The fabric layer of the support layer may contain or consist of one or more fibers selected from the group consisting of polyester, polypropylene, polyamide, cotton and natural fibers. Preferably, the fabric layer consists of polypropylene fibers. In a preferred embodiment, the fibers are polypropylene fibers and the cover layer is based on polypropylene. Therefore, the sheet material can be made of a single material.

[0074] The support layer can consist of a single layer, ie a textile layer which forms 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, ie a support layer and a cover layer and an optional lacquer layer.

[0075] In addition to the fabric layer, the support layer can also include other layers. For example, the support layer can successively include a fabric layer with a thickness of 0.3 to 5 mm, a foam layer with a thickness of 0.5 to 10 mm as described below, and a fabric layer with a thickness of 0.3 to 2.5 mm, wherein each fabric layer is preferably directly bonded to the foam layer. Direct bonding eliminates the possibility of an additional layer or adhesive layer between the fabric layer and the foam layer. Therefore, the sheet material can include several layers without any adhesive layer. The foam layer can have adhesive properties so that it can be firmly adhered to the top or bottom fabric or textile layer without the need to add another adhesive.

[0076] In an embodiment, the adhesive layer can be arranged between the fabric layer and the foam layer and / or between the foam layer and the optional fabric layer. If the support layer comprises two adjacent fabric layers, they can be bonded to each other by the adhesive layer. The adhesive can be a polyolefin adhesive, a polyurethane adhesive, an acrylic adhesive or a hot melt adhesive based on polyurethane (PUR). The adhesive can be used with a thickness of 40 μm. The support layer can successively comprise a fabric layer, an adhesive layer, a foam layer, an adhesive layer and a fabric layer.

[0077] The composition of the optional foam layer is not limited. The foam layer can be composed of or contain the following: PVC foam, TPE-based foam, PUR-based foam and / or EVA / EMA foam. Preferably, the foam layer is composed of or contains polyolefin foam. The thermoplastic polyolefin (TPO) described herein for the cover layer can also be used for the foam layer. In a preferred embodiment, the foam layer is composed of or contains polypropylene foam (PP foam). Polypropylene (PP) is understood here as a polymer or copolymer in which the weight ratio of propylene is >50%. The foam layer can contain common additives, such as lubricants, stabilizers, fillers such as inorganic fillers, and / or pigments.

[0078] Foams can be produced by first sheet extrusion, followed by cross-linking and then expansion.

[0079] The thickness of the foam layer may be 0.5 to 10 mm. Preferably, the thickness of the foam layer is 1.0 to 5.0 mm. The density of the foam layer is preferably 30 to 300 kg / m 3 , more preferably 30 to 150 kg / m 3 , even more preferably 40 to 100 kg / m 3The higher the density of the foam, the higher its strength. The gel content mentioned herein is measured according to ASTM D2765-16. The sample is weighed (initial weight) and placed in xylene at 180°C for 24 hours, the dissolved material is separated, and the weight of the remaining material is determined (final weight); gel content [%] = [(final weight) / (initial weight)] x 100%.

[0080] The support layer may be an opaque layer or a translucent layer. In particular, the fabric layer may be an opaque layer or a translucent layer. The light transmittance of the support layer may be 1% to 100%, 1% to 90%, 1% to 50% or 5% to 50%, preferably 1% to 30%, more preferably 2 to 20%.

[0081] Covering

[0082] The density of the cover layer is preferably at least 800 kg / m 3 , more preferably higher than 850kg / m 3 Preferably, the covering layer is dense. The covering layer may consist of one or more layers. Preferably, the covering layer consists of a single layer.

[0083] The cover layer is thermoplastic. This property requires that the overall degree of crosslinking is not too high. The gel content is preferably less than 20%, more preferably less than 15%. The gel content may be from 0 to 50%.

[0084] The melting point and Shore A hardness of the cover layer are mainly determined by the properties of the thermoplastic elastomer. The thermoplastic elastomer used for the cover layer may or may not have a melting temperature. In the former case, the melting temperature is preferably 100 to 180°C, more preferably 110 to 170°C. Therefore, the melting point of the cover layer composition is preferably 100 to 180°C, more preferably 110 to 170°C.

[0085] The covering layer may contain conventional additives such as plasticizers, stabilizers, anti-aging agents (e.g. antioxidants), fillers and pigments (silicon dioxide, 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 additives are UV stabilizers, which may be selected from one or more of benzotriazole or hindered amine light stabilizers.

[0086] The cover layer of the sheet preferably has a texture, i.e. a three-dimensional structured surface, on the uppermost surface covered with paint. 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. Texture can be introduced by known methods, such as embossing or using a release paper having a surface with a negative image showing the desired texture structure. The depth of the texture is less than the thickness of the cover layer, and is preferably 10 to 500 μm, more preferably 50 to 500 μm, and even more preferably 50 to 300 μm. The texture can be produced using conventional methods. The texture can be produced as a paper texture. For this purpose, the starting material is coated on a structured carrier material such as a release paper. Thereafter, the carrier paper is removed, and a surface coating is applied in several steps by gravure printing. Alternatively, preferably after coating, while applying pressure and temperature, the texture or embossing is applied to the artificial leather surface by an embossing roller.

[0087] The cover layer contains a thermoplastic elastomer (TPE). A thermoplastic elastomer is defined as an elastomer that exhibits thermoplastic behavior. The term "thermoplastic" refers to a polymer or polymer composition that exhibits thermoplastic properties, particularly thermoreversibility. TPE exhibits rubber elasticity within a normal use temperature range. TPE is a copolymer or elastomeric alloy, i.e., a physical mixture of polymers composed of materials having both thermoplastic properties and elastomeric properties. Copolymers are statistical copolymers or block copolymers, which are composed of a main polymer such as polyethylene, and whose crystallinity is reduced to a certain extent due to randomly incorporated comonomers such as vinyl acetate. In block copolymers, the hard segments and soft segments in the molecule are clearly separated (e.g., SBS, SIS). Therefore, copolymers can be composed of soft elastomers and hard thermoplastic parts. Elastomer alloys are blends of finished polymers. Desired performance can be obtained by changing the mixing ratio.

[0088] In general, there are the following general classes of TPEs (named according to ISO 18064): styrenic block copolymers (TPS), thermoplastic polyolefin elastomers (TPO), thermoplastic vulcanizates (TPV), thermoplastic polyurethanes (TPU), thermoplastic copolyesters (TPC), melt-processed rubbers and thermoplastic polyamides (TPA).

[0089] The TPE used in the present invention may belong to one general category, or may be a blend of TPEs from two or more categories. In addition, the TPE may be selected from one category, and may be one TPE in one category or a blend of two or more TPEs in one category. The content of TPE in the cover layer is preferably at least 50%. The total content of thermoplastic polymers, i.e., TPE and other thermoplastic polymers in the cover layer is preferably at least 80%, more preferably at least 90%. Preferably, the total content of polymers in the cover layer consists of TPE and other thermoplastic polymers. More preferably, the total content of polymers in the cover layer consists of thermoplastic polymers, i.e., TPE and other thermoplastic polymers such as TPO, and is at least 80%, most preferably at least 90%.

[0090] Common elastomers include ethylene propylene rubber (EPR), EPDM (ethylene-propylene-diene rubber), ethylene-octene (EO), ethylbenzene (EB), and styrene ethylene butadiene styrene (SEBS). Thermoplastic polyurethane (TPU) is a thermoplastic elastomer composed of a linear multi-block copolymer consisting of hard segments and soft segments.

[0091] In the present invention, the terms "elastomer" and "rubber" are used synonymously. They refer to polymers that exhibit elastic properties and are crosslinked. They may or may not have a gel content. Their gel content may be from 1% to 50%, preferably from 2% to 50%, more preferably from 5% to 50%.

[0092] The rubber can be selected from the following group: natural rubber (NR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), carboxylated nitrile rubber (XNBR), butyl rubber (IIR), chlorinated butyl rubber (CIIR), brominated butyl rubber (BIIR), chloroprene rubber (CR), styrene butadiene rubber (SBR), polybutadiene (BR), ethylene-propylene-diene terpolymer (EPDM), ethylene-propylene rubber (EPR or EPM), silicone rubber, acrylic rubber (ACM), ethylene-vinyl acetate copolymer rubber (EVM), polyurethane rubber (PU) and any combination thereof. The rubber can also be a styrene-based thermoplastic elastomer (STPE). In particular, the rubber can be selected from the following group: ethylene / α-olefin copolymer rubber (EAM) and ethylene / α-olefin / diene terpolymer rubber (EADM). Preferably, the diene in the ethylene-α-olefin-diene rubber is preferably a non-conjugated diene. Suitable non-conjugated dienes include dicyclopentadiene, alkyl dicyclopentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-heptadiene, 2-methyl-1,5-hexadiene, cyclooctadiene, 1,4-octadiene, 1,7-octadiene, 5-ethylidene-2-norbornene, 5-n-propylene-2-norbornene and 5-(2-methyl-2-butenyl)-2-norbornene. In a preferred embodiment, the rubber component includes ethylene-α-olefin-diene rubber. The ethylene-α-olefin-diene rubber may include an α-olefin having 3 to 8 carbon atoms. The α-olefin in the EAM or EADM rubber is preferably propylene; in this case, the rubber is referred to as EP(D)M. Here, EPM may also be referred to as EPR. A mixture of the rubbers mentioned above may also be used.

[0093] In a preferred embodiment of the present invention, the rubber consists of EPDM and EPR. In this case, EPDM preferably constitutes at least 80% of the total rubber content in the cover layer. Preferably, the TPV raw material contains EPDM, and the TPO raw material contains EPR.

[0094] EPDM is made of ethylene, propylene and diene comonomers that enable crosslinking via a sulfur vulcanization system. EPDM contains crosslinking and is preferably fully cured, i.e. crosslinked to at least 98%, most preferably crosslinked to 100%. The content of propylene is preferably 45% to 85%. Preferred dienes for making EPDM rubber are ethylidene norbornene (ENB), dicyclopentadiene (DCPD) and vinyl norbornene (VNB). EPDM is preferably crosslinked via sulfur vulcanization or by using peroxides. Propylene reduces the formation of typical polyethylene crystallinity. EPDM is a semi-crystalline material with an ethylene-type crystal structure at higher ethylene contents, becoming essentially amorphous when the ethylene content approaches 50%. EPDM can be compounded with fillers such as carbon black and calcium carbonate and plasticizers such as paraffin oil.

[0095] EPR (also known as "EPM") is a random copolymer of ethylene and propylene. EPR is similar to EPDM, but does not contain diene units. It is crosslinked using free radical methods such as peroxides. EPRs of different properties can be obtained by changing the monomer ratio. These properties are, for example, viscosity or crystallinity. EPRs from amorphous to semi-crystalline structures can be obtained. EPR preferably contains 40% to 80%, more preferably 40% to 60% ethylene units. It is generally known that EPR copolymers containing less than about 40% ethylene have poor elasticity at low temperatures, and therefore may provide compositions that are too rigid and lack the balance of mechanical properties over a wide temperature range required for most automotive applications. At high ethylene contents, generally above about 60% ethylene units, separate crystalline ethylene domains may form within the rubber component, and interphase adhesion and miscibility are reduced. EPR may be included in the thermoplastic resin composition in an amount of 10 to 60%, preferably 15 to 40%. Resins with less than 10% EPR are more rigid and less flexible. The presence of a rubber component in a high content above about 60% reduces stiffness and tensile strength.

[0096] The rubber component contained in the sheet according to the present invention is preferably contained in a thermoplastic vulcanizate (TPV), which can be used as a raw material for producing a cover layer. TPV, as a category of TPE, combines the characteristics of vulcanized rubber with the processing properties of thermoplastics. TPV contains rubber particles cured by vulcanization. The rubber particles are encapsulated in a thermoplastic matrix.

[0097] In the present invention, the rubber particles are made of the rubber described herein, and the thermoplastic matrix is ​​made of the TPO described herein. The resin component of the TPV may be composed of 10-90 parts by weight of a polyolefin resin and 90-10 parts by weight of a corresponding rubber, preferably 10-80 / 80-20 parts by weight, more preferably 30-70 / 70-30 parts by weight. In the present invention, TPV based on polypropylene (PP) and EPDM rubber is preferred.

[0098] TPVs can be prepared by mixing polyolefins with vulcanized rubber in particle form, or by a process known as dynamic vulcanization. Dynamic vulcanization consists of the following steps: thoroughly mixing a blend of compatible polymers, then introducing a crosslinking system into the mixture while continuing the mixing process. The mechanical properties of TPVs increase with the degree of crosslinking of the rubber phase and inversely with the particle size of the rubber domain. TPVs can be processed using conventional thermoplastic processes such as injection molding, blow molding, and extrusion.

[0099] TPVs can be compounded with additives. In particular, TPVs can contain different ingredients such as reinforcing fillers (carbon black, mineral fillers), stabilizers, plasticizing oils, and curing systems.

[0100] The thermoplastic elastomer may have a particle shape. The particles are preferably embedded in a matrix of other polymers present in the layer. The particle size is preferably below 10 μm, more preferably below 1 μm. Preferably, at least 90% of the particles have a size less than 10 μm. The size can be determined by scanning electron microscopy (SEM) of a cross section of the layer. The longest diameter of the particle image in the SEM micrograph is defined as its size.

[0101] In addition to thermoplastic elastomers, the cover layer may also contain thermoplastic polymers, in particular thermoplastic polyolefins (TPO). The degree of crosslinking in thermoplastic polyolefins is low. Its gel content is preferably less than 5%, more preferably less than 2%. TPO is a polymer produced by chain polymerization from olefins such as ethylene, propylene, 1-butene or isobutylene. It is a semi-crystalline thermoplastic polymer that is easy to process. Examples of TPO are polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyisobutylene (PIB) and polybutene (PB, polybutene-1). Polyethylene (PE) is defined here as a polymer or copolymer in which the weight ratio of ethylene exceeds 50%. Polypropylene (PP) is defined here as a polymer or copolymer in which the weight ratio of propylene exceeds 50%. Examples of TPO are blends of polyethylene (PE) and polypropylene (PP). Examples of PE are HDPE, LDPE and LLDPE. HDPE has a weakly branched polymer chain and therefore has a molecular weight of 0.94 g / cm 3 Up to 0.97g / cm 3 LDPE and LLDPE are described below. The properties of TPO can be affected by adding elastomers or other substances such as talc.

[0102] Examples of blends of rubber with TPO are blends of ethylene propylene diene rubber (EPDM) with polyethylene (PE) and / or polypropylene (PP), blends of ethylene propylene rubber (EPM) with polypropylene (PP) and / or polyethylene (PE) and ethylene propylene blends, and blends of styrene ethylene butadiene styrene (SEBS) with TPOs such as polyethylene (PE) and / or polypropylene (PP). The composition may contain an elastomer such as EPR or EPDM or SEBS to such an extent and the degree of crosslinking that the composition is still thermoplastic.

[0103] The cover layer may be an opaque layer or a semi-transparent layer. The light transmittance of the cover layer may be 1% to 100%, 1% to 90%, 1% to 50% or 5% to 50%, preferably 1% to 30%, more preferably 2 to 20%.

[0104] Composite structure

[0105] The sheet contains a composite structure. The composite structure itself is not a layer.

[0106] The composite structure is defined by the interaction between the support layer and the cover layer. Preferably, this interaction is only a physical interaction and does not include chemical interactions such as chemical bonds. The composite structure consists of a portion of the support layer and a portion of the cover layer that interpenetrate each other. The degree of interpenetration of the cover layer is 5% to 99%, preferably 10% to 70%, more preferably 15% to 60%, and is defined as follows: the degree of interpenetration [%] = [(the thickness of the composite structure) / (the thickness of the cover layer)] x 100%. The thickness of the cover layer is defined as the thickness of the composite structure plus the thickness of the portion of the cover layer that is not part of the composite structure. Similarly, the degree of interpenetration of the fabric layer is 10% to 90%, preferably 10% to 70%, more preferably 15% to 60%, and is defined as follows: the degree of interpenetration [%] = [(the thickness of the composite structure) / (the thickness of the fabric layer)] x 100%. The thickness of the fabric layer is defined as the thickness of the composite structure plus the thickness of the portion of the fabric layer that is not part of the composite structure.

[0107] The degree of interpenetration as defined above is limited. The advantage of this limitation is that the support layer structure is not visible on the top of the covering layer and does not affect the appearance of the sheet. The degree of interpenetration of the covering layer into the fabric layer of the support layer is also limited, which maintains the flexibility of the sheet. The ratio of the support layer that is not part of the composite structure in the thickness direction is preferably at least 10%, more preferably at least 20%, and most preferably at least 50%. In one embodiment, the degree of interpenetration is defined as [(thickness of the composite structure) / (thickness of the fabric layer)] x 100%, which is 10% to 90%, preferably 10% to 70%, and the thickness of the fabric layer is the thickness of the composite structure plus the thickness of the part of the fabric layer that is not part of the composite structure.

[0108] The composite structure can be characterized by the structure of the sheet cross section perpendicular to the layer plane, as observed with a microscope. In one embodiment, the reaction conditions such as pressure and temperature can be adjusted so that the density of the support layer is only slightly reduced in the lamination step. In one embodiment, the part of the support layer as a part of the composite structure has at least 80% of the area density of the support layer that is not a part of the composite structure. The density of the fabric layer can be adjusted so that the composite structure is composed of a support layer and a cover layer of similar ratios. As observed by a microscope of the sheet cross section perpendicular to the layer plane, the composite structure can be composed of 30 to 70% of the support layer material and 70 to 30% of the cover layer material. The lamination process can be adjusted so that the hollow space in the fabric layer of the support layer (which is usually filled with gas such as air) is (almost) completely filled with the cover layer composition to obtain a dense composite structure.

[0109] The composite structure may be opaque or translucent. The light transmittance of the composite structure may be 1% to 100%, 1% to 90%, 1% to 50% or 5% to 50%, preferably 1% to 30%, more preferably 2 to 20%.

[0110] paint layer

[0111] The paint layer is an optional layer located on the cover layer. The paint can be a conventional material. The thickness of the paint layer can be preferably 1 to 30 μm, more preferably 3 to 10 μm. The paint layer is directly applied to the top of the cover layer as a facing of the sheet, and is used to protect the artificial leather from chemical agents, physical damage such as scratches or wear and ultraviolet radiation. Surface painting can further reduce the surface adhesion of the artificial leather. Conventional paints for artificial leather in vehicle interiors can be used. For example, solvent-based or water-based polyurethanes cross-linked with isocyanates or having UV curing properties are suitable. The surface coating used to protect the surface is usually composed of one or more, preferably up to four transparent paint layers. Alternatively, the surface coating can be colored by adding color pigments.

[0112] The paint layer can be an opaque layer or a translucent layer. Preferably, the paint layer is translucent and does not affect the translucency of other layers of the sheet.

[0113] Manufacturing method

[0114] The sheet material according to the present invention can be prepared by a method comprising the following steps:

[0115] (a) providing a cover layer composition containing at least a thermoplastic elastomer;

[0116] (b) at least partially melting the thermoplastic elastomer of the cover layer composition;

[0117] (c) forming a laminate of a cover layer composition comprising an at least partially molten thermoplastic elastomer and a support layer comprising a fabric layer such that the cover layer composition and the fabric layer at least partially interpenetrate each other; and

[0118] (d) cooling the cover layer composition to obtain a sheet.

[0119] The preparation method may start with a cover layer composition consisting of a thermoplastic elastomer and other components of the final cover layer.

[0120] In step (a), the cover layer composition may be provided in the form of (i) particles, such as particles of the cover layer composition, or (ii) a finished film comprising the cover layer composition.

[0121] In the case of (i), step (b) comprises melting the particles of the cover layer composition, preferably using an extruder. In the case of (ii), step (b) comprises heating the film on at least one side to at least partially melt the cover layer composition contained in the film. The cover layer composition can be selected so that its melting temperature is lower than the melting temperature of the fabric layer of the support layer. 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, the cover layer composition can be selected so that its melting temperature is equal to or higher than the melting temperature of the support layer and can withstand the temperature of the molten cover layer when in contact with the molten cover layer. 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.

[0122] In step (c), preferably use the extruder under the situation of (i) to carry out laminate formation.Can molten cover layer composition be extruded and applied on supporting layer, or can molten cover layer composition be extruded on carrier, and supporting layer can be applied on cover layer composition.In both cases, cover layer composition, supporting layer and process conditions must be selected so that cover layer and supporting layer interpenetrate each other to the desired degree.If pressure is applied when forming laminate, then pressurize supporting layer, thereby make molten cover layer composition can be more easily, more deeply penetrated.Therefore, the adhesion between supporting layer and cover layer can be stronger.

[0123] In the case of (ii), step (c) includes the step (c1) of forming a laminate of a film and a support layer and the step (c2) of forming a textured structure by embossing the other side of the film, wherein steps (c1) and (c2) are performed simultaneously. Step (c) can be performed using two cylindrical pieces. A laminate can be formed by pressing the partially molten side of the film onto the support layer while conveying through the narrow gap between the two cylindrical pieces. Using a cylindrical piece with a defined gap width enables the preparation of a sheet of a composite structure with a defined thickness. The cylindrical piece in contact with the cover layer can have a textured structure embossed into the surface of the cover layer. Therefore, forming a laminate and embossing can be performed in a single step.

[0124] Example

[0125] The following parameters are used to describe the properties of the sheet structure of the present invention:

[0126] Weight per unit area: DIN EN ISO 2286-2; Thickness: DIN EN ISO 2286-3 (surface area 7 cm2; diameter 30 mm; weight 3 N; pressure 0.42 N / cm2; layer thickness determined by microscopy); Tear propagation resistance: DIN EN ISO 4674-1; Separation force: DIN EN ISO 2411.

[0127] Table 1 shows the results of Examples (Examples 1 to 3) and Comparative Example (Comparative Example 1).

[0128] Table 1

[0129]

[0130] "+" means that the sample fully exhibits the performance for the intended use.

[0131] The criteria for cutting and sewing performance are the foldability and wrinkling of the sample. The sample meets the requirements of separation force of at least 20N (longitudinal direction) and at least 25N (transverse direction). The sample meets the requirements of tear propagation resistance of at most 15N (longitudinal and transverse direction).

Claims

1. A sheet material comprising a support layer, a cover layer and a composite structure, wherein The support layer comprises a fabric layer, The cover layer is a dense layer containing a thermoplastic elastomer and is arranged on the fabric layer of the support layer, and The composite structure is composed of a portion of the support layer and a portion of the covering layer interpenetrating each other, wherein the degree of interpenetration is defined as [(thickness of the composite structure) / (thickness of the covering layer)] x 100%, which is 5% to 99%, and the thickness of the covering layer is the thickness of the composite structure plus the thickness of the portion of the covering layer that is not part of the composite structure.

2. The sheet material according to claim 1, wherein the degree of interpenetration is from 15% to 60%.

3. The sheet material according to claim 1 or 2, wherein the content of the thermoplastic elastomer in the cover layer composition is at least 50%. 4 . The sheet material according to claim 1 , wherein the cover layer composition has a Shore A hardness of less than 90 according to DIN 53505.

5. A sheet material according to any preceding claim, wherein the thickness of the portion of the cover layer which is not part of the composite structure is at least 0.04 mm.

6. A sheet material according to any one of the preceding claims, wherein the support layer comprises a fabric layer having a thickness of 0.3 to 5.0 mm; the cover layer has a thickness of 0.1 to 1.5 mm; and the composite structure has a thickness of 0.01 to 1.0 mm.

7. The sheet according to any one of the preceding claims, wherein the support layer comprises in sequence a fabric layer having a thickness of 0.3 to 5.0 mm, a foam layer having a thickness of 0.5 to 10 mm and an optional fabric layer having a thickness of 0.3 to 2.5 mm; or wherein the support layer comprises two fabric layers bonded to each other by an adhesive layer.

8. The sheet material according to any one of the preceding claims, wherein the support layer comprises or consists of one or more fibers selected from the group consisting of: Polyester, polypropylene, polyamide, cotton or other natural fibers.

9. Sheet material according to any one of the preceding claims, wherein the sheet material is obtainable by a method comprising thermal bonding or thermomechanical bonding of the cover layer and the support layer.

10. The sheet material according to any one of the preceding claims, wherein the sheet material has a tear propagation resistance of 10 to 50 N in the longitudinal direction and in the transverse direction according to DIN EN ISO 4674-1.

11. The sheet material according to any one of the preceding claims, wherein the sheet material is artificial leather.

12. Use of the sheet material according to any one of claims 1 to 11 as a surface material in a vehicle interior.

13. A method for preparing a sheet according to any one of claims 1 to 11, the method comprising the following steps: (a) providing a cover composition comprising a thermoplastic elastomer; (b) at least partially melting the thermoplastic elastomer of the cover layer composition; (c) forming a laminate of the cover layer composition comprising the at least partially molten thermoplastic elastomer and a support layer comprising a fabric layer such that the cover layer composition and the fabric layer of the support layer at least partially interpenetrate each other; as well as (d) cooling the cover layer composition to obtain the sheet.

14. The method according to claim 13, wherein the melting in step (b) and the laminate formation in step (c) are performed using an extruder.

15. The method according to claim 13, wherein step (a) comprises providing the cover layer composition in the form of a film made of the cover layer composition, step (b) comprises heating the film on at least one side to at least partially melt the thermoplastic elastomer, and step (c) comprises a step (c1) of forming a laminate by contacting the one side of the film with the support layer and a step (c2) of forming a textured structure by embossing the other side of the film, wherein steps (c1) and (c2) are performed simultaneously.

Images