Sheet comprising foam layer and thermoplastic elastomer

Abstract

A sheet comprising a support layer, an intermediate layer disposed on the support layer, and a cover layer disposed on the intermediate layer, where the cover layer is a compact layer, the intermediate layer is a foam layer or comprises a foam layer, and at least one of the intermediate layer and the cover layer comprises a thermoplastic elastomer, where the support layer is directly bonded to the intermediate layer, no adhesive layer is arranged between the supporting layer and the middle layer; a method of making a sheet; a stitched product obtainable by stitching the sheet; a method of making a stitched product; and using the sheet or the stitched product as a material for the interior of the vehicle.

Description

Technical Field

[0001] The present invention relates to a sheet material comprising a supporting layer, an intermediate layer and a covering layer, wherein the covering layer is a compact layer, the intermediate layer consists of or contains a foam layer, and the compact layer and / or the foam layer contains a thermoplastic elastomer, a method for producing the sheet material, and use of the sheet material as a material used in vehicle interiors, such as artificial leather. Background Art

[0002] EP3766687 A1 and EP3533601 A1 disclose a composite structure comprising a foam layer, a fabric layer, and a tight covering layer in the order shown, and comprising a thermoplastic elastomer. The composite structure is soft and flexible and suitable for use in vehicle interiors. WO2019 / 042610 A1 discloses a composite structure comprising a fabric layer, a foam layer, and a tight covering layer, for use as a soft and flexible material as a covering material in a vehicle.

[0003] Problems to be solved by the present invention

[0004] In view of the prior art, the problem underlying the present invention is to provide a structure having improved properties in terms of low weight, low wrinkle formation, softness and flexibility in order to enable good handling during processing such as sewing. Summary of the Invention

[0005] The problem addressed by the present invention is solved by providing a sheet material according to the present invention.

[0006] The present application encompasses the following preferred aspects.

[0007] [1] A sheet material comprising a support layer, an intermediate layer disposed on the support layer, and a cover layer disposed on the intermediate layer, wherein the cover layer is a compact layer, the intermediate layer is a foam layer or includes a foam sublayer, and at least one of the intermediate layer and the cover layer includes a thermoplastic elastomer, wherein the support layer is directly bonded to the intermediate layer, and no adhesive layer is disposed between the support layer and the intermediate layer. [1-1] The sheet material according to aspect [1], wherein the cover layer is directly bonded to the intermediate layer.

[0008] [1-2] The sheet according to any one of the aforementioned aspects, wherein the layers included in the intermediate layer are directly bonded to each other, and the layers included in the cover layer are directly bonded to each other.

[0009] [1-3] A combination of aspects [1-1] and [1-2] is preferred.

[0010] [1-4] The sheet material according to any one of the preceding aspects, wherein the density of the foam layer or foam sublayer is less than 800 kg / m 3 , preferably less than 650kg / m 3 , more preferably less than 500kg / m 3 .

[0011] [1-5] The sheet material according to any one of the preceding aspects, wherein the total density of the support layer, the intermediate layer and the cover layer is less than 800 kg / m 3 , preferably less than 650kg / m 3 .

[0012] [1-6] A sheet according to any of the preceding aspects, wherein the sheet can be folded to form a double-layer structure, wherein the two B sides of the sheet 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 the sheet preferably shows no visible damage or change at the folded edges after folding and unfolding.

[0013] [1-7] The sheet material according to any one of the preceding aspects, wherein the sheet material is suitable for preparing a stitched product obtainable by stitching the sheet material.

[0014] [1-8] A sheet according to any one of the preceding aspects, wherein the sheet is suitable for preparing a stitched product that can be obtained by stitching at least two parts of a sheet, wherein the two parts belong to the same sheet or different sheets; and the stitched product can preferably be obtained by folding the sheet, placing the A-side surfaces or B-side surfaces of the two parts of the sheet together to provide a contact area, and stitching the sheet in the contact area.

[0015] [1-9] The sheet according to any one of the preceding aspects, wherein the sheet shows no damage and no change after 100,000 flexing cycles in a test according to DIN 53351.

[0016] [1-10] The sheet according to any one of the preceding aspects, wherein the cover layer composition has a Shore A hardness of less than 90 according to DIN 53505.

[0017] [1-11] The sheet according to any one of the preceding aspects, wherein the sheet has a tear propagation force of 10 to 50 N in a first direction and a second direction perpendicular to the first direction according to DIN EN ISO 4674-1.

[0018] [1-12] The sheet according to any one of the aforementioned aspects, wherein the covering layer or the paint layer coating the covering layer and having a thickness of less than 40 μm is the uppermost layer of the sheet.

[0019] [1-13] The sheet according to any one of the aforementioned aspects, wherein at least one of the intermediate layer and the cover layer is composed of at least two sub-layers.

[0020] [1-14] The sheet according to any one of the preceding aspects, wherein the intermediate layer consists of two sub-layers and the cover layer is a single layer, or wherein the intermediate layer is a single layer and the cover layer consists of two sub-layers.

[0021] [2] The sheet according to any one of the preceding aspects, wherein the intermediate layer comprises or consists of a tight sublayer and a foam sublayer.

[0022] [2-1] The sheet according to aspect [2], wherein the compact sublayer or the foam sublayer is arranged on the support layer.

[0023] [2-2] The sheet according to any one of the preceding aspects, wherein the thickness of the sub-layer directly bonded to the support layer is greater than 0.1 mm, preferably at least 0.15 mm.

[0024] [3] A sheet according to any of the preceding aspects, wherein the foam layer or sublayer of the intermediate layer directly bonded to the support layer (i.e., the foam layer when the intermediate layer is a foam layer, or the lowermost layer of the intermediate layer when the intermediate layer includes a foam sublayer) comprises a thermoplastic elastomer.

[0025] [3-1] The sheet according to aspect [3], wherein the intermediate layer comprises or consists of a tight sublayer and a foam sublayer, wherein the tight sublayer or the foam sublayer is directly bonded to the support layer and comprises a thermoplastic elastomer.

[0026] [3-2] A sheet according to a combination of aspects [3-1] and [2-2].

[0027] [4] The sheet according to any one of the preceding aspects, wherein each sub-layer of the foam layer or the intermediate layer comprises a thermoplastic elastomer.

[0028] [5] The sheet according to any one of the preceding aspects, wherein the foam layer or each sub-layer of the intermediate layer comprises a thermoplastic elastomer, and wherein the cover layer comprises a thermoplastic elastomer.

[0029] [5-1] The sheet according to any one of the aforementioned aspects, wherein all sub-layers of the intermediate layer and the cover layer contain a thermoplastic elastomer.

[0030] [5-2] The sheet according to any one of the preceding aspects, wherein the content of the thermoplastic elastomer in the layer is at least 50%.

[0031] [5-3] The sheet according to any one of the aforementioned aspects, wherein the content of the thermoplastic elastomer in the total amount of the intermediate layer and the cover layer is at least 30%, preferably at least 50%.

[0032] [5-4] The sheet according to any one of the preceding aspects, wherein the content of the thermoplastic elastomer in each sub-layer of the intermediate layer and the cover layer is at least 30%, preferably at least 50%.

[0033] [6] A sheet according to any of the preceding aspects, wherein the support layer comprises or consists of a fabric layer, wherein the fabric layer preferably comprises one or more fibers selected from polyester, polyolefin, polyamide, polyurethane and cotton or other natural fibers.

[0034] [6-1] The sheet according to any of the preceding aspects, wherein the support layer is a fabric layer. [6-2] The sheet according to the combination of aspects [1-5] and [6-1]. [6-3] The sheet according to the combination of aspects [6-2] and [5-3]. [6-4] The sheet according to the combination of aspects [6-2] and [1-6], preferably [6-3] and [1-6]. [6-5] The sheet according to the combination of aspects [6-1] and [4].

[0035] [7] The sheet material according to any one of aspects [6] to [6-5], wherein the fabric layer of the support layer is directly bonded to the intermediate layer.

[0036] [8] The sheet material according to any one of aspects [6] to [6-5], wherein the sheet material comprises a composite structure consisting of only a portion of the fabric layer and only a portion of the intermediate layer interpenetrating each other.

[0037] [8-1] The sheet according to aspect [8], wherein the degree of interpenetration of the intermediate layer as defined herein is 5% to 90%.

[0038] [8-2] The sheet according to aspect [8-1], wherein the degree of interpenetration of the intermediate layer is less than 50%, preferably less than 20%.

[0039] [9] The sheet according to any one of aspects [6] to [8-2], wherein the degree of interpenetration of the fabric layers as defined herein is from 5% to 90%.

[0040] [9-1] The sheet according to aspect [9], wherein the degree of interpenetration of the fabric layers is less than 50%, preferably less than 20%.

[0041] [9-2] A sheet according to a combination of aspects [8-2] and [9-1].

[0042]

[10] The sheet material according to any one of the preceding aspects, wherein the support layer is a fabric layer having a thickness of 0.1 to 2.0 mm, the intermediate layer has a thickness of 1.0 to 5.0 mm, and the cover layer has a thickness of 0.1 to 1.5 mm.

[0043]

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

[0044]

[12] A method of producing a sheet as described in any one of aspects [1] to

[11] , comprising thermally or thermomechanically bonding the support layer, the intermediate layer, and the cover layer.

[0045] [12-1] The method according to aspect

[12] , wherein the composite structure is formed in a joining step, wherein at least a portion of the intermediate layer composition or a film made of the intermediate 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 intermediate layer composition or a film made of the intermediate layer composition is in a molten form and at least a portion of the support layer is in a molten form.

[0046] [12-2] The method according to aspect

[12] or [12-1], wherein the process of bonding the intermediate layer and the support layer includes applying pressure and heat treatment in a single step.

[0047]

[13] A sewn product obtainable by sewing the sheets according to any one of aspects [1] to

[11] .

[0048]

[14] A method for producing a stitched product, comprising stitching the sheet material according to any one of aspects [1] to

[11] .

[0049]

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

[11] or the stitched product according to aspect

[13] as a material for vehicle interior, preferably for seat applications.

[0050] Advantages of the present invention

[0051] The sheet material according to the present invention is lightweight, soft, and flexible. It exhibits minimal wrinkling when bent. These properties make the sheet material easy to handle, particularly for sewing. Another advantage is that the sheet material is easily recyclable when the materials of the layers are selected from the same compound family.

[0052] Compared to conventional sheets that include a foam layer on the B-side of a fabric layer, the sheet material according to the present invention, particularly the cover layer, can be made thinner because there is no risk of the fabric layer being visible through the cover layer. Furthermore, the properties of the foam layer (e.g., softness) are not affected by the fabric layer positioned over the foam layer. Therefore, the tactile properties of the sheet material according to the present invention can be improved, and the fabric layer can be selected independently of requirements such as the softness of the foam layer.

[0053] Embodiments of the present invention

[0054] The sheet of the present invention comprises a support layer, an intermediate layer and a cover layer as essential layers.

[0055] The intermediate layer is disposed on the support layer, and the cover layer is disposed on the intermediate layer. As used herein, the term "disposed on" means that the layers are directly bonded to one another, i.e., they are directly stacked on one another without any intervening material, such as an adhesive layer. Direct bonding of the cover layer to the intermediate layer is preferred. Similarly, the sublayers of the intermediate layer and the sublayers of the cover layer are preferably directly bonded to one another.

[0056] The support layer is positioned on the B side of the sheet, and the cover layer is positioned on the A side of the sheet. Herein, the terms "A side" and "B side" refer to the entire sheet or a single layer, and the terms "above" and "below" the sheet or layer refer to the positions of the A side and B side of the sheet or layer, respectively. The sheet itself is a layer structure. The B side of the sheet may include any additional structures, such as a carrier layer or any other layer or functional structure.

[0057] Herein, unless expressly stated otherwise, the terms “sheet”, “support layer”, “intermediate layer” and “cover layer” refer to “sheet according to the present invention”, “support layer contained in the sheet according to the present invention”, “intermediate layer contained in the sheet according to the present application” and “cover layer contained in the sheet according to the present invention”, respectively.

[0058] The sheet is preferably flexible and elastic and can preferably be reversibly folded, i.e., folded from an initial state and then unfolded to its original state. Preferably, the sheet can be folded to form a two-layer structure, wherein the two B sides of the sheet overlap each other and contact each other at the folded edges, and the two-layer structure can be unfolded to its original state. Preferably, the sheet, in particular the folded edges, shows no visible damage or changes, such as whitening of the creases, after folding and unfolding. Visible damage or changes referred to herein can be measured at room temperature according to the standard described in DIN 53351.

[0059] Preferably, the sheet is suitable for producing a stitched product that can be obtained by sewing at least two sheets or two parts of the same sheet. The stitched product can be produced by folding the sheet, bringing the two B-side portions of the sheet together to form a contact area, and sewing the two parts of the sheet in the contact area. In order for the sheet to have the desired properties, such as ease of processing during sewing, the sheet must not be too stiff. Therefore, the sheet's hardness is preferably less than 30 Shore D, more preferably less than 90 Shore A. To be suitable for sewing, it is also important that the sheet has a suitable stitch tear force. According to DIN EN ISO 23910, this 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 producing a stitched product that can be obtained by sewing at least two layers of the sheet. The sheet is flexible and preferably shows no damage or change after 100,000 flexing cycles, more preferably after 1,000,000 flexing cycles, in a test according to DIN 53351.

[0060] The intermediate layer and the cover layer may exhibit elasticity and / or thermoplasticity. The thermoplastic nature allows thermal bonding of the layers without the use of adhesives. Thermoplasticity requires that the overall degree of crosslinking is not too high. The gel content is preferably between 0% and 20%.

[0061] In the present invention, the compact layer is formed by having a density higher than 800 kg / m 3 The density of the foam layer is defined by having a density of less than 800 kg / m 3 is limited by the density.

[0062] The support layer, intermediate layer, and cover layer are preferably joined to each other without the use of adhesives. The structure can be formed exclusively by thermal bonding. Preferably, the support layer does not melt at the temperatures used in thermal bonding. In the case of a connection based solely on thermal bonding, the connection is reversible, and the layers can be separated at room temperature or by heating to at least partially melt the layers. The connection between the layers can be strengthened by treating the sheet with radiation or an electron beam from the B side of the support layer to form chemical bonds between the layers. In this case, the connection between the layers is irreversible, that is, the layers cannot be separated by at least partially melting the cover layer. Thermal bonding of the fabric layer as the support layer and intermediate layer can result in interpenetrating layers. Preferably, complete interpenetration is not included, and both the intermediate layer and the fabric layer have non-interpenetrating layer portions in the thickness direction. As a result, the fabric layer is not exposed at the surface of the intermediate layer surface, thereby not affecting the appearance of the sheet, and the fabric layer that is not fully penetrated by the intermediate layer material remains flexible.

[0063] In the present invention, the thickness of the intermediate layer is defined as the thickness of the composite structure plus the thickness of the portion of the intermediate layer that is not part of the composite structure. Similarly, 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. Therefore, the thickness of the sheet can be the total thickness of the raw material layers 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 plane of the layer 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 over the length of the layer or structure.

[0064] The sheet material may contain additives such as fillers, plasticizers, flame retardants, color pigments, stabilizers, lubricants, UV absorbers, light stabilizers, antioxidants, antimicrobial agents, and foaming agents. The additives may be independently contained in the fabric layer and / or the intermediate layer and / or the cover layer.

[0065] The sheet material according to the present invention may be opaque or translucent. Generally, a translucent structure allows more transmittance of visible light than an opaque structure when light is emitted from the same light source.

[0066] The covering layer can be coated with a lacquer layer. The lacquer can be a conventional material. The thickness of the lacquer layer can preferably be 1 to 30 μm, more preferably 3 to 10 μm. The lacquer layer is applied directly on top of the covering layer to provide a finish for the sheet and protect it from chemical agents, physical damage (such as scratches or abrasions), and UV radiation. Conventional lacquers used for artificial leather in vehicle interiors can be used, for example, lacquers based on aliphatic polyurethanes containing silicone. The lacquer layer typically consists of one or more, preferably up to four, clear lacquer layers. Alternatively, the surface coating can be colored by adding color pigments.

[0067] In the present invention, an adhesive can be used to bond the layer structures to each other. The adhesive can be a polyolefin adhesive, a polyurethane adhesive, an acrylic adhesive, or a polyurethane (PUR)-based hot melt adhesive. The adhesive can be used in a thickness of less than 40 μm.

[0068] In the present invention, the terms "comprising," "containing," "including," and "having" are inclusive and, therefore, specify the presence of the recited features, steps, layers, and / or components, but do not preclude the presence or addition of one or more other features, steps, layers, components, and / or groups. The method steps, processes, and operations described herein should not be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It should also be understood that additional steps may be employed.

[0069] Whenever it is mentioned in the context of this specification that an individual composition or layer is based on or made of a certain material, this should be interpreted as the corresponding material forming 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" or "made of..." refers to a content of more than 50%, preferably 90%, and more preferably 95%.

[0070] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. For example, layers and components are often described in the singular, such as "a" layer or "comprising a" layer. Unless otherwise indicated, such singular forms are intended to include more than one of the indicated components or layers.

[0071] The term "and / or" includes any and all combinations of one or more associated listed items. Unless otherwise expressly stated, percentages (%) of component contents are weight percentages (mass %). Similarly, "parts" are parts by weight.

[0072] Unless otherwise stated, the standards and specifications referred to herein refer to the latest versions available at the time of filing this application.

[0073] Support layer

[0074] The sheet material comprises a support layer, which can be made of any flexible material, such as a polymer film, a foam layer or a fabric layer. Preferably, the support layer is composed of a fabric layer. The thickness of the fabric layer is preferably 0.1-3.0 mm, more preferably 0.1-2.0 mm.

[0075] Examples of fabric layers are knitted fabrics, woven fabrics, nonwoven fabrics, glass fiber fabrics, spunlace or spacer fabrics. Knitted fabrics are flexible materials made by forming interlocking bundles of yarns or threads, which are produced by spinning raw fibers into long and twisted lengths. The basic components of the fabric layer, i.e. filaments, fibers, yarns, threads, etc., are collectively referred to as fibers in this article. Spacer fabrics are flexible materials formed by two surface fabric layers held at a defined distance by spacer threads. The fabric layers are not compact and include a large volume ratio of hollow spaces that are usually filled with air. The density of the fabric layer is preferably 100 to 500 kg / m 3 , more preferably 100 to 300 kg / m 3 The fabric layer may comprise or consist of one or more fibers selected from polyester, polyolefins such as polyethylene or polypropylene, polyurethane, polyamide, cotton and natural fibers.

[0076] Middle layer

[0077] The intermediate layer consists of a foam layer or comprises a foam layer. In the latter case, the intermediate layer comprises at least two layers, ie sublayers, one of which is a foam layer and any of which can be arranged on a support layer. The sublayers are preferably directly bonded to each other.

[0078] The composition of the foam layer is not limited. The foam layer can be composed of or contain PVC foam, TPE-based foam, PUR-based foam and / or EVA / EMA foam. Preferably, the foam layer is composed of or contains polyolefin foam. In a preferred embodiment, the foam layer comprises polypropylene foam (PP foam). Polypropylene (PP) is understood here to be a polymer or copolymer of this type with a weight proportion of propylene of >50%. The foam layer can contain common additives, such as lubricants, stabilizers, fillers (such as inorganic fillers) and / or pigments. The foam can be produced by first extruding the sheet, then crosslinking, and then expanding.

[0079] The foam layer may have a thickness of 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 or foam sublayer is preferably less than 500 kg / m 3 , preferably 30-300kg / m 3 , more preferably 30-150kg / m 3 , even more preferably 40-100 kg / m 3 . The 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%. The foam layer can be prepared by known methods and can be foamed using chemical foaming agents, expandable microspheres and / or physical foaming agents.

[0080] In addition to the foam layer contained in the intermediate layer, a foam layer may be contained in the support layer or on the B side of the sheet.

[0081] The compact layer optionally contained in the intermediate layer may be made of the polymer material described in connection with the cover layer.

[0082] Covering

[0083] The sheet material comprises or consists of a compact covering layer. In the former case, the covering layer comprises at least two compact layers, ie sub-layers. The sub-layers are preferably directly bonded to each other.

[0084] In addition to the optional thermoplastic elastomer, the layer of the cover layer can be made of or include any polymer material, such as a polyolefin, polyvinyl chloride or polyurethane. The polyolefin can be a thermoplastic polyolefin (TPO). Examples of TPO are polyethylene (PE) and polypropylene (PP). Polyethylene (PE) is defined herein as a polymer or copolymer having an ethylene weight ratio greater than 50% by weight. Polypropylene (PP) is defined herein as a polymer or copolymer having a propylene weight ratio greater than 50% by weight. Examples of TPO are blends of polyethylene (PE) and polypropylene (PP). Examples of PE are HDPE, LDPE and LLDPE.

[0085] The thickness of the cover layer is preferably 0.05 mm to 2.0 mm, more preferably 0.1 mm to 1.5 mm. The density of the dense cover layer or dense sublayer is higher than 800 kg / m 3 , preferably higher than 850kg / m 3 .

[0086] The cover 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 modifiers, adhesion promoters, etc.). Examples of additives are UV stabilizers, which may be selected from one or more components of benzotriazole or hindered amine light stabilizers.

[0087] The cover layer preferably has a texture, which is a three-dimensional structured surface on the top side covered with lacquer. The texture may be present only in the cover layer or in both the cover layer and the lacquer layer. Textured sheets can be used as artificial leather. 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 300 μm. The texture can be generated using conventional methods.

[0088] Thermoplastic elastomers

[0089] Thermoplastic elastomer (TPE) is contained in the intermediate layer and / or the cover layer.

[0090] TPE is defined as an elastomer that exhibits thermoplastic properties. The term "thermoplastic" refers to a polymer or polymer composition that exhibits thermoplastic properties, particularly thermoreversibility. TPE exhibits rubber elasticity within the normal operating temperature range. TPE is a copolymer or elastomeric alloy, that is, a physical mixture of polymers composed of materials with thermoplastic and elastomeric properties. Copolymers are statistical copolymers or block copolymers, which consist of a main polymer such as polyethylene, whose crystallinity is reduced to a certain extent by randomly introduced comonomers such as vinyl acetate. In block copolymers, the hard and soft segments in the molecule are clearly separated (e.g., SBS, SIS). Therefore, copolymers can be composed of soft elastomers and hard thermoplastic components. Elastomeric alloys are blends of finished polymers. The desired properties can be obtained by varying the mixing ratio.

[0091] Typically, there are the following general types of TPEs (designations according to ISO 18064): styrene block copolymers (TPS), thermoplastic polyolefin elastomers (TPO), thermoplastic vulcanizates (TPV), thermoplastic polyurethanes (TPU), thermoplastic copolyesters (TPC), melt-processed rubbers and thermoplastic polyamides (TPA).

[0092] The TPE used in the present invention may belong to a general class or may be a blend of TPEs from two or more classes. Furthermore, the TPE may be selected from a class and may be one TPE from a class or a blend of two or more TPEs from a class. The content of TPE in the intermediate layer and / or cover layer is preferably at least 50%. The total content of thermoplastic polymers (i.e., TPE and other thermoplastic polymers) in the intermediate layer and / or cover layer is preferably at least 80%, more preferably at least 90%. Preferably, the total content of polymers in the intermediate layer and / or cover layer consists of TPE and other thermoplastic polymers. More preferably, the total content of polymers in the intermediate layer and / or 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%.

[0093] Common elastomers include ethylene propylene rubber (EPR), EPDM (ethylene propylene diene monomer), ethylene octene (EO), ethylbenzene (EB), and styrene ethylene butadiene styrene (SEBS). Thermoplastic polyurethane (TPU) is a thermoplastic elastomer composed of linear segmented block copolymers consisting of hard and soft segments.

[0094] In the present invention, the terms "elastomer" and "rubber" are used synonymously. They refer to crosslinked polymers that exhibit elastic properties. They may or may not have a gel content. Their gel content may range from 1% to 50%, preferably from 2% to 50%, and more preferably from 5% to 50%.

[0095] The rubber can be selected from natural rubber (NR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), 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 ethylene / α-olefin copolymer rubber (EAM) and ethylene / α-olefin / diene terpolymer rubber (EADM). The diene in the preferred ethylene-α-olefin-diene rubber is preferably a non-conjugated diene. Suitable non-conjugated dienes include dicyclopentadiene, alkyldicyclopentadiene, 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 comprises ethylene-α-olefin-diene rubber. The ethylene-α-olefin-diene rubber may comprise an α-olefin having 3-8 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. Mixtures of the above rubbers may also be used.

[0096] In a preferred embodiment of the present invention, the rubber is composed of EPDM and EPR. In this case, EPDM preferably constitutes at least 80% of the total rubber content in the intermediate layer and / or cover layer. Preferably, EPDM is contained in the TPV raw material and EPR is contained in the TPO raw material.

[0097] EPDM is made of ethylene, propylene and a diene comonomer that can be crosslinked by a sulfur vulcanization system. EPDM contains crosslinking and is preferably fully cured, i.e., crosslinked to a degree of at least 98%, most preferably to a degree of 100%. The propylene content is preferably 45%-85%. Preferred dienes for making EPDM rubber are ethylidene norbornene (ENB), dicyclopentadiene (DCPD) and vinyl norbornene (VNB). EPDM is preferably crosslinked by 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 at ethylene contents approaching 50%. EPDM can be mixed with fillers such as carbon black and calcium carbonate, as well as plasticizers such as paraffin oil.

[0098] 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. Different properties of EPR can be obtained by varying the monomer ratios. These properties include viscosity or crystallinity. EPR with amorphous to semi-crystalline structures can be obtained. EPR preferably contains 40-80%, more preferably 40-60%, ethylene units. EPR copolymers containing less than about 40% ethylene are generally known to have poor elasticity at low temperatures and may therefore provide compositions that are too rigid and lack the balance of mechanical properties over the wide temperature range required for most automotive applications. At high levels of ethylene (typically above about 60% ethylene units), individual crystalline ethylene domains can form within the rubber component, reducing interphase adhesion and miscibility. EPR can be included in the thermoplastic resin composition in amounts of 10 to 60%, preferably 15 to 40%. Resins with less than 10% EPR are more rigid and less flexible. The presence of high levels of the rubber component, above about 60%, reduces stiffness and tensile strength.

[0099] 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 an intermediate layer and / or a cover layer. TPV, a type of TPE, combines the properties of vulcanized rubber with the processing properties of thermoplastics. TPV contains rubber particles that are cured by vulcanization. The rubber particles are encapsulated in a thermoplastic matrix.

[0100] In the present invention, the rubber particles are made from the rubber described herein, and the thermoplastic matrix is made from the TPO described herein. The resin component of the TPV can be composed of 10-90 parts by weight of a polyolefin resin and 90-10 parts by weight of the corresponding rubber, preferably 10-80 / 80-20 parts by weight, and more preferably 30-70 / 70-30 parts by weight. In the present invention, TPVs based on polypropylene (PP) and EPDM rubber are preferred.

[0101] TPVs can be prepared by mixing polyolefins with vulcanized rubber in granular form or by a process known as dynamic vulcanization. Dynamic vulcanization involves intimately mixing a blend of compatible polymers and then introducing a crosslinking system into the blend while continuing the mixing process. The mechanical properties of TPVs improve with the inverse of the degree of crosslinking of the rubber phase and the particle size of the rubber domain. TPVs can be processed using conventional thermoplastic processes such as injection molding, blow molding, and extrusion.

[0102] 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.

[0103] The thermoplastic elastomer can be in the form of particles. The particles are preferably embedded in a matrix of the other polymers present in the layer. The particle size is preferably less than 10 μm, more preferably less than 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.

[0104] The layer comprising a thermoplastic elastomer may further comprise a thermoplastic polymer, in particular a thermoplastic polyolefin (TPO) as described herein. Examples of blends of rubber and 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 comprise an elastomer, such as EPR or EPDM or SEBS, to an extent and degree of crosslinking such that the composition is still thermoplastic.

[0105] Composite structure

[0106] The sheet material may comprise a composite structure. Such a composite structure is not a layer, but rather is defined by the interaction between the fabric layer and the intermediate layer. Preferably, this interaction is solely physical and does not include chemical interactions such as chemical bonds. The composite structure comprises a portion of the fabric layer and a portion of the contact layer, where the contact layer is the lowermost sublayer of the intermediate layer composed of foam or a foam layer. The lowermost layer of the intermediate layer may be a compact layer or a foam layer.

[0107] In each case, the term "portion" means that the corresponding layer is not included in the composite structure throughout the thickness direction of the corresponding layer. In other words, complete interpenetration is excluded, and both the fabric layer and the contact layer have non-interpenetrating layer portions in the thickness direction. Therefore, the fabric layer is not exposed on the A-side of the contact layer surface, and the contact layer is not exposed on the B-side of the fabric layer surface.

[0108] The composite structure can be characterized by the structure of a cross-section of the sheet perpendicular to the layer plane as observed using a microscope. The density of the contact layer can be adjusted so that the composite structure is composed of similar proportions of fabric and contact layers. The composite structure can be composed of 30 to 70% fabric layer material and 70 to 30% contact layer material. The corresponding areas can be simply determined by microscopically observing a cross-section of the sheet perpendicular to the layer plane, thereby determining the percentages based on mass or area. The lamination process can be adjusted so that the hollow spaces in the fabric layer (typically filled with a gas, such as air) are (almost) completely filled with the contact layer composition to achieve a compact composite structure.

[0109] The degree of interpenetration is defined as follows: Interlayer interpenetration [%] = [(composite structure thickness) / (contact layer thickness)] x 100%. The contact layer thickness is defined as the thickness of the composite structure plus the thickness of the portion of the contact layer that is not part of the composite structure, i.e., plus the thickness of the contact layer above the composite structure. Fabric layer interpenetration [%] = [(composite structure thickness) / (fabric layer thickness)] x 100%. The fabric layer thickness 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, i.e., plus the thickness of the fabric layer below the composite structure.

[0110] Manufacturing method

[0111] The sheet according to the present invention can be prepared by a method comprising the following steps:

[0112] (a) providing an intermediate layer composition;

[0113] (b) at least partially melting the interlayer composition;

[0114] (c) forming a laminate of the at least partially melted interlayer composition and a support layer comprising or consisting of a fabric layer, such that the interlayer composition and the fabric layer at least partially interpenetrate each other; and

[0115] (d) cooling the interlayer composition.

[0116] In step (a), the interlayer composition may be provided in the form of (i) particles, such as particles of the interlayer composition, or (ii) a finished film comprising the interlayer composition.

[0117] In the case of (i), step (b) comprises melting pellets of the interlayer composition, preferably using an extruder. The interlayer may be applied after step (d) to obtain the sheet. In the case of (ii), step (b) comprises heating the film on at least one side to at least partially melt the interlayer composition contained in the film. The interlayer composition may be selected to have a melting temperature lower than that of the fabric layer of the support layer. Thus, the molten interlayer composition penetrates the hollow spaces of the support layer without melting the fibers of the support layer. In this case, the interlayer and support layer can be separated from each other by heating. Alternatively, the interlayer composition may be selected to have a melting temperature equal to or higher than that of the support layer and, upon contact with the molten interlayer, represents the temperature of the molten interlayer. Thus, the interlayer composition at least partially melts the fibers of the support layer upon penetrating the hollow spaces. In this case, the interlayer and support layer are more strongly bonded to each other. In the case of (ii), the cover layer may be applied after step (d) or may be laminated to the back side of the film containing the interlayer composition.

[0118] In step (c), in the case of (i), it is preferred to use an extruder for lamination. The molten intermediate layer composition can be extruded and applied to the support layer, or the molten intermediate layer composition can be extruded onto a carrier, and the support layer can be applied to the intermediate layer composition. In both cases, the intermediate layer composition, the support layer and the process conditions must be selected so that the intermediate layer and the support layer interpenetrate each other to the desired extent. If pressure is applied in forming the laminate, the support layer is compressed, so that the molten intermediate layer composition can penetrate more easily and more deeply. As a result, the adhesion between the support layer and the intermediate layer can be stronger.

Claims

1. A sheet material comprising a support layer, an intermediate layer arranged on the support layer, and a cover layer arranged on the intermediate layer, wherein the cover layer is a compact layer, the intermediate layer is a foam layer or contains a foam sublayer, and at least one of the intermediate layer and the cover layer contains a thermoplastic elastomer, wherein the support layer is directly bonded to the intermediate layer, and no adhesive layer is arranged between the support layer and the intermediate layer.

2. The sheet material of claim 1, wherein the intermediate layer comprises or consists of a tight sublayer and a foam sublayer.

3. The sheet material of claim 2, wherein the foam layer or the sub-layer of the intermediate layer directly bonded to the support layer comprises a thermoplastic elastomer.

4. The sheet material according to any one of the preceding claims, wherein the foam layer or each sub-layer of the intermediate layer comprises a thermoplastic elastomer.

5. The sheet material according to any one of the preceding claims, wherein the foam layer or each sub-layer of the intermediate layer comprises a thermoplastic elastomer, and wherein the cover layer comprises a thermoplastic elastomer.

6. A sheet material according to any one of the preceding claims, wherein the support layer comprises or consists of a textile layer comprising one or more fibres selected from polyester, polyolefin, polyamide, polyurethane and cotton or other natural fibres.

7. The sheet material of claim 6, wherein the fabric layer of the support layer is directly bonded to the intermediate layer.

8. The sheet material according to claim 7, wherein The sheet material comprises a composite structure consisting of only a portion of the fabric layer and only a portion of the intermediate layer, with only a portion of the fabric layer and only a portion of the intermediate layer interpenetrating each other.

9. The sheet material according to any one of claims 6 to 8, wherein The sheet material comprises a composite structure consisting of a portion of the fabric layer and a portion of the intermediate layer, wherein the portion of the fabric layer and the portion of the intermediate layer interpenetrate each other, wherein the degree of interpenetration of the fabric layers, defined as [(thickness of the composite structure) / (thickness of the fabric layer)] x 100%, is 5% 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.

10. The sheet material according to any one of the preceding claims, wherein the support layer is a fabric layer having a thickness of 0.1 to 2.0 mm, the intermediate layer has a thickness of 0.1.0 to 5.0 mm, and the cover layer has a thickness of 0.1 to 1.5 mm.

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

12. A method of making a sheet material according to any one of claims 1 to 11, comprising thermally or thermomechanically bonding the support layer, the intermediate layer and the cover layer.

13. A seamed product obtainable by seaming the sheet material according to any one of claims 1 to 11.

14. A method of producing a stitched product, comprising stitching the sheet material according to any one of claims 1 to 11.

15. Use of the sheet material according to any one of claims 1 to 11 or the stitched product according to claim 13 as a vehicle interior material.