Oil-resistant composite material

Abstract

Oil-resistant, planar composite material (laminate) consisting of a core layer and at least one outer layer or layers arranged above and / or below, wherein the outer layer(s) consist of materials selected from nonwoven fabrics and are not bonded to the core layer by means of a separate adhesive, wherein the core layer has a single-layer structure, and wherein the core layer consists of a polymer mixture containing a thermoplastic elastomer from the group of styrene / isoprene / styrene triblock copolymers (SIS) in a proportion of 20 to 40 wt%, wherein the SIS triblock copolymer of the core layer contains less than 10% or less than 1% diblock components, and furthermore contains a polymer selected from the group of olefinic polymers in a proportion of 50 to 80 wt%, wherein the olefinic polymers are selected from the group of copolymers of ethylene and propylene.and optionally other non-polymeric excipients, and wherein the polymer mixture of the middle layer contains no additives of plasticizer(s), in particular mineral oils.

Description

Technical area

[0001] The present invention describes an oil-resistant, elastic, flat composite material (laminate) and a method for its production. State of the art

[0002] Nonwovens (also often referred to in German by the English term "non-woven fabrics" or "non-wovens"; see Ullmann's Encyclopedia of Technical Chemistry, 3rd edition, Volume 17, page 287ff.) and composites of elastomers with nonwovens find a wide variety of applications in technology, particularly in the production of sanitary, personal care, and hygiene articles. Among other things, the nonwoven provides a pleasant haptic feel, particularly for articles that are in contact with the wearer's skin surface for extended periods of time while worn. Other elastomers bonded to the nonwoven—often a film made of a suitable elastomeric polymer material—contribute further desirable properties to the composite material, such as increased mechanical strength combined with flexibility and impermeability to aqueous liquids.

[0003] A widespread problem in this context is the fact that the corresponding materials frequently come into contact with personal care products that contain both an aqueous and an oily phase (skin creams and emulsions) or are even based entirely on an oily carrier (body oils). In particular, those components of the composite material that consist of elastomeric polymer materials are exposed to additional stress, as the resistance to oily liquids is known to vary greatly between different polymers.On the one hand, oily liquids (e.g., the oily components of the aforementioned body care products) can diffuse into such a polymer material and adversely affect its mechanical properties simply by their presence; on the other hand, interactions between oily liquids and other components (e.g., dyes, fillers, plasticizers, etc.) of the polymer materials - if present - cannot be ruled out. In the worst case, the product made of the composite material is destroyed or loses its beneficial properties. For example, reduced tear strength leads to the formation of holes in the polymer materials, causing the composite material as a whole to lose its barrier properties against aqueous liquids.

[0004] To solve this problem, various approaches have been proposed in the prior art to make such composite materials resistant to the effects of oily liquids. WO 2004 / 060 665 A1 proposes bonding a central elastomer film to the nonwoven fabric on both sides using a suitable adhesive, the adhesive being resistant to oily liquids. This results in a composite material with a total of five layers (nonwoven fabric, adhesive, elastomer film, adhesive, nonwoven fabric), with the adhesive layers providing resistance to oily liquids.

[0005] WO 2008 / 038 168 A2 presents a corresponding composite material comprising an elastic film containing a semi-crystalline, propylene-based polymer with a density equal to or less than 0.88 g / cm 3 . The oil resistance results from the chemical nature of the elastic film.

[0006] EP 3 187 333 A1 describes an oil-resistant laminate with two outer nonwoven layers and a central elastomer layer, wherein the elastomer layer itself consists of at least two layers, wherein at least one layer is an olefin-based elastomer which is responsible for the oil resistance.

[0007] US patents US 9 827 696 B2 and US 9 765 459 B2 relate to vapor-permeable, substantially water-impermeable multi-layer articles.

[0008] US patent application US 2007 / 0 142 801 A1 relates to an oil-resistant, elastic fastening adhesive and laminated articles containing such an adhesive.

[0009] The US patent application US 2012 / 0 088 423 A1 relates to a composition for a stretchable film. Description of the invention

[0010] The present invention provides an oil-resistant, sheet-like composite material consisting of a middle layer and at least one outer layer or layers arranged above and / or below, wherein the outer layers consist of materials selected from nonwoven fabrics and are not attached to the middle layer by means of a separate adhesive, wherein the middle layer has a single-layer structure, and wherein the middle layer consists of a polymer mixture containing at least one thermoplastic elastomer from the group of styrene / isoprene / styrene triblock copolymers (SIS) in a proportion of 20 to 40% by weight, wherein the SIS triblock copolymer of the middle layer contains less than 10% or less than 1% of diblock components, and further contains at least one polymer selected from the group of olefinic polymers,wherein the olefinic polymers are selected from the group of copolymers of ethylene and propylene in a proportion of 50 to 80% by weight, and wherein the polymer mixture of the middle layer contains no additives of plasticizer(s), in particular mineral oils.

[0011] In a further embodiment, the polymer mixture of the middle layer contains no further polymeric components other than the SIS triblock copolymers and the olefinic polymers mentioned above. However, non-polymeric auxiliaries such as fillers, processing aids, waxes, pigments, and the like may be present. In a further embodiment, the polymer mixture of the middle layer consists of a SIS triblock copolymer, an olefinic polymer, and optionally one or more of the aforementioned auxiliaries.

[0012] In a further embodiment, the material for the outer layers is selected from nonwovens which have been bonded by means of water-jet bonding (also called “water-jet bonding”, “water entanglement” or “spunlace”).

[0013] In a further embodiment, the material for the outer layers is selected from single-layer nonwovens.

[0014] In a further embodiment, the material for the outer layers is selected from the group of single-layer nonwovens, for the production of which a fiber material consisting of a uniform fiber type was chosen. In a further embodiment, the material for the middle layer is selected from the group of single-layer nonwovens, for the production of which a fiber material consisting of a mixture of different fiber types was chosen.

[0015] In a further embodiment, the middle layer has a thickness determined by measurement under a microscope of 100 micrometers or less, or in the range between 20 and 100 micrometers, or in the range between 20 and 70 micrometers.

[0016] In a further embodiment, the composite material consists of two outer layers which are connected to the middle layer, with one outer layer being arranged above and another outer layer being arranged below the middle layer.

[0017] In a further embodiment, the composite material has an elastic capacity, measured using the test method described below, of more than 9 N / 100 mm. In a further embodiment, the composite material has an elastic capacity of more than 10 N / 100 mm, or more than 11 N / 100 mm.

[0018] In a further embodiment, the present invention relates to a sheet-like composite material (laminate) consisting of a middle layer and at least one outer layer or layers arranged above and / or below, wherein the outer layer(s) consist of materials selected from nonwoven fabrics and are not attached to the middle layer by means of a separate adhesive, wherein the middle layer has a single-layer structure, and wherein the static shear strength of a bond between an adhesive tape and the nonwoven layer of the outer layer increases by more than ten times, or more than twelve times, when the bond is aged for fourteen days at 50°C.

[0019] In a further embodiment, this composite material has an elastic capacity, measured using the test method described below, of more than 9 N / 100 mm. In a further embodiment, the composite material has an elastic capacity of more than 10 N / 100 mm, or more than 11 N / 100 mm.

[0020] In a further embodiment, this composite material is oil-resistant. In a further embodiment, the oil resistance is determined according to the method specified in this description, wherein the composite material exhibits no pitting in this test within a period of three hours, four hours, or six hours.

[0021] In further embodiments, the middle layer of the oil-resistant composite material has the compositions described above.

[0022] The invention further provides a method for producing a composite material according to the invention, which is characterized in that the middle layer is applied to or introduced between the outer layer(s) by extrusion lamination. For this purpose, the falling extrusion film is first brought together between two outer layers in a roll nip. The outer layers can be fully bonded to the still plastic film by lightly pressing them together in a bonding unit located immediately behind the extrusion unit. Alternatively, it is possible to press the outer layers more firmly into the still plastic film by increasing the pressure in selected areas than in the remaining areas. This pressing can also take place in a separate step while the elastic film is in a plastic state.Subsequently, the composite material can be activated partially or over its entire surface by pre-stretching using conventional methods such as ring rolling or contactless stretching using a tensioning frame or similar.

[0023] It has surprisingly been found that a composite material can achieve increased resistance to oily liquids (oil resistance) in that the middle layer consists of a polymer mixture which contains at least one thermoplastic elastomer from the group of styrene / isoprene / styrene triblock copolymers (SIS) in a proportion of 20 to 40% by weight, wherein the SIS triblock copolymer of the middle layer contains less than 10% or less than 1% of diblock components, and further contains at least one polymer selected from the group of olefinic polymers, wherein the olefinic polymers are selected from the group of copolymers of ethylene and propylene in a proportion of 50 to 80% by weight, and wherein the polymer mixture of the middle layer does not contain any additives of plasticizer(s), in particular mineral oils.The content of diblock components can be determined using methods known in the art (such as gel permeation chromatography).

[0024] Plasticizers, or so-called "plasticizers," serve to make materials softer and more flexible. All plasticizing substances used for this purpose in the prior art and known to those skilled in the art can be understood as "plasticizers" within the meaning of this description.

[0025] These include poly-alpha-olefins (e.g. amorphous polyalphaolefins), (functionalized) oligomers such as oligobutadiene, -isoprene, liquid nitrile rubbers, liquid terpene resins, vegetable and animal oils and fats, ester plasticizers such as phthalates, adipates, mellitics, phosphorus-containing esters or functionalized acrylates.

[0026] The group of plasticizers also includes mineral oils, which can be paraffinic, aromatic, or naphthenic. A subtype of these mineral oils is known as paraffin oils or white oils (e.g., Catenex S or T from Shell). Some of these are technical white oils, which are barely hydrogenated or only hydrogenated once and may still contain traces of aromatic hydrocarbon compounds (e.g., Flavex from Shell).

[0027] Another category includes medical white oils, which are highly purified, multiply refined paraffin oils free of residues such as aromatic hydrocarbons and sulfur compounds (e.g., Risella X or Ondina X from Shell). White oils are therefore preferred for use in products that require high levels of purity without contamination by substances that are harmful to health, such as aromatic hydrocarbons, etc., such as in the cosmetics or hygiene industries.

[0028] It was also surprisingly found that the absence of such a plasticizer in the middle layer increases the durability of the bond between a composite material according to the invention and an adhesive tape coated with an adhesive. Such bonds using adhesive adhesives or adhesive tapes are relevant in practice. For example, in the hygiene articles already mentioned in the introduction, the closure that secures and holds the article in the worn position is often achieved by such a bond—adhesive tape directly on the nonwoven layer of the composite material. It is advantageous if such a bond is not prematurely released, as this would lead to a loss of wearing comfort or even necessitate a premature replacement of the hygiene article.Without wishing to be bound by a theoretical explanation, it can be assumed that in the case of plasticizer-containing (and especially mineral oil-containing) middle layers in the composite materials, diffusion of the plasticizer into the adhesive layer of the adhesive tape occurs, which can adversely alter the adhesive properties of the adhesive. Such diffusion cannot occur in the composite materials according to the invention because no plasticizer is present. In one embodiment, the composite material is characterized in that the static shear strength of a corresponding bond between an adhesive tape and the nonwoven layer increases by more than tenfold or more than twelvefold when the bond is aged for fourteen days at 50°C, as detailed in the test described below.

[0029] Nonwoven fabrics suitable for use within the invention include, in principle, all nonwoven fabrics that can be processed using the inventive manufacturing process (extrusion lamination) with the inventive core layer materials. Such nonwoven fabrics and processes for their production are known in the art (cf. Ullmann's Encyclopedia of Industrial Chemistry, 3rd edition, Volume 17, pages 287ff; cf. also 5th edition, Volume A17, chapter "Nonwoven Fabrics," pages 565-587).

[0030] In principle, all fiber materials that can be processed into nonwovens, i.e., into a scrim of staple fibers or continuous fibers, using known manufacturing processes are suitable as textile fiber materials for the production of nonwovens for use in the composite materials according to the invention. The only exceptions are mineral fibers and glass fibers. Natural, semi-synthetic, or fully synthetic fibers can be used. Uniform fiber materials as well as mixtures of different fiber materials can also be employed. Suitable fiber materials and the criteria for their use are familiar to the person skilled in the art from their general technical knowledge (cf. Ullmann, loc. cit.).

[0031] Examples of suitable fiber materials include fully synthetic fibers, such as polyethylene, polyethylene terephthalate, polypropylene, polyester, viscose, polyamide, cotton, or wool fibers. In one embodiment, the fibers are made of polypropylene.

[0032] In the field of nonwoven production, two-component fibers are also known, which can impart special properties to the resulting nonwoven. A subgroup of these fibers are the two-component fibers made of two synthetic polymers, such as polyester-polyamide, polyester-polypropylene, polyamide 6-polyamide 6,6, and the like. Furthermore, it is known that such two-component fibers can be modified during production so that the two components are found in precisely defined spatial sections of the fibers (e.g., as core and sheath, as segments, and the like). All such embodiments are fundamentally encompassed by the nonwovens for the production of the composite materials according to the invention.

[0033] Nonwovens can also be produced using known prior art methods in either single-layer or multi-layer configurations, meaning that the fiber material can be selected differently across the cross-section of the nonwoven. Both single-layer and multi-layer nonwovens are encompassed for the production of the composite materials according to the invention.

[0034] In one embodiment, the nonwovens are single-layer nonwovens, i.e. the type and composition of the fibers does not change across the cross-section of the outer layer.

[0035] Various processes can be used in the production of nonwovens to bond the fibers to each other or to the carrier material. Mechanical, adhesive, and thermal processes are used. In principle, all of these processes are suitable for producing nonwovens for use in the composite materials of the invention.

[0036] In a further embodiment of the invention, the nonwovens are selected from the group of nonwovens bonded by water-jet bonding (also called "water entanglement" or "spunlace"), which consist of a fiber web, i.e., a web of staple fibers, carded nonwovens, or continuous fibers. This manufacturing process is characterized, among other things, by the fact that it is particularly suitable for obtaining nonwovens with predefined patterns (e.g., perforated or screen patterns) depending on the number and arrangement of the water jet nozzles. The fibers are intermingled in the web by the penetrating water jets.

[0037] Composite materials according to the invention can be produced by the extrusion lamination process known in the prior art, wherein the polymer mixture of the middle layer is introduced as a hot, liquid film onto or between the nonwoven layer(s), whereby upon cooling a direct bond is formed between the middle layer and the nonwoven layer(s).

[0038] The properties of the composite materials according to the invention are determined using the following test methods. Oil resistance test:

[0039] A square test section of the composite material measuring 70 x 70 mm is clamped on two opposite sides into a metal rail and stretched by 100% by vertical tension, i.e., to a length of 140 mm in the tensile direction. A 0.030 g drop of the test fluid is applied to the center of the clamped test section using a dropper pipette. The test section is visually inspected repeatedly over a period of three hours. If no mechanical changes (holes, cracks, etc.) are observed at or around the application site after three hours, the material is considered oil-resistant according to the definition used here.

[0040] The standardized test fluids used are almond oil (CAS No. 90320-37-9, a relative density of 0.916 (20°C), an acid number of ≤ 1.0 mg KOH / g, and a peroxide number of ≤ 5), and paraffin oil (from VWR Chemicals, Ref. No. 301440ZK), both commonly used in skin care products. Resistance to one of these two oils is sufficient to define resistance within the meaning of this description. Elastic capacity test:

[0041] A test sample of the composite material with a width of 130 mm (“original width”) and a length of 90 mm is clamped (transverse to the machine direction) in a tensile machine (clamp spacing 70 mm) and subjected to the following stress-relaxation cycle: 1. Preload with a force of 0.1 N applying a pulling speed of 150 mm / min. 2. Load 1: Elongation from 0% to 100% at a tensile speed of 500 mm / min. Elongation of 100% is held for 10 seconds. Measured value: "Tension 1" in N at 50% elongation. 3. Unloading 1: Elongation 100% to 0% with a return speed of 150 mm / min. 4. Load 2: Elongation from 0% to 100% with a tensile speed of 500 mm / min. 5. Unloading 2: Elongation from 100% to 0% with a return speed of 150 mm / min. The 0% elongation is held for 60 seconds. 6. Load 3: Elongation to 100% with a tensile speed of 500 mm / min 7. Unloading 3: Elongation from 100% to 0% with a return speed of 150 mm / min. Measured value: "Tension 3" in N at 50% elongation.

[0042] The elastic capacity is calculated according to formula (1): "Tension1"[N]−"Tension3"[N]=ElasticCapacity[N] Test for bond stability (static shear test): 1. Aim of the test

[0043] Testing of the anchoring of a composite material according to the invention with an adhesive tape (for example: diaper ear and diaper tape) and its creep strength under the influence of temperature. 2. Test material / air conditioning Sample: at least 24 hours Air conditioning: 23 ± 2 °C and 50 ± 5 % relative humidity (RT) 3. Devices

[0044] Shearing stand with time recording, heating cabinet (37°C), 1000 g weights, roll-over device (2.5 kg pressure roller) 4. Test parameters

[0045] Adhesive tape: The adhesive tape used in this test (CP 1 M 50 from Lohmann-koester) consists of a PP spunbond with 60 g / m 2, which is coated with a solvent-free, UV-curable silicone and an HMPSA (pressure-sensitive hotmelt) applied on the opposite side with an application weight of 50 g / m 2 and a processing temperature of 180°C, with a viscosity at 180°C of 32850 mPas and an instant adhesive strength (Quickstick) on steel of 27 N / 25 mm (test method described in the appendix). Width of adhesive tape (used here: Windeltape CP 1 M 50 from Lohmann-koester): 25 mm Test specimen width of composite material (e.g. diaper ear material (e.g. ESP)): 60 mm (in case of deviation, mark clearly) Loading direction: transverse to the machine direction of the composite material Rolling: 2.5 kg - 300 mm / min., 1x forward and back Load: 1000 g Load angle: 180° Test temperature: 37°C 5. Start of implementation

[0046] The composite material (e.g., diaper ear material) is cut out in a rectangular shape perpendicular to the grain. The adhesive tape (e.g., diaper tape) is affixed to silicone paper for cutting and cut perpendicular to the grain. The cut must be clean and straight. After cutting, the adhesive tape is immediately laminated to one end of the composite material. The overlapping area is 16 mm × 25 mm. The test specimen is then rolled over using the roll-over device.

[0047] A hole is punched in the center of the uncoated part of the adhesive tape and secured with staples. At the other end of the composite material, both sides are reinforced with approximately 14 mm wide coated hook-and-loop fasteners and secured with staples. 6. Retention time before exams

[0048] The shear strength is determined for unaged specimens without any waiting time. For the aging step, they are clamped between two Pertinax disks (100 mm x 260 mm x 8 mm) and stored in an oven at elevated temperature with a 2 x 5 kg load for the specified aging period.

[0049] By default, samples in this test are aged for 14 days at 50°C. 7. Further implementation

[0050] The finished test specimens are then suspended in the shearing furnace using a clamp at least the width of the test specimen and loaded with a weight. The load is applied perpendicular to the direction of travel of the composite material. It is important that this step is performed quickly, otherwise the shearing furnace will lose too much heat (temperature loss can lead to higher shear values).

[0051] The time elapsed from the time the weight is attached until the test specimen falls is recorded. 8. Result

[0052] Evaluation: here h / 25 mm at 37°C (h = hours, determined with an accuracy of two decimal places)

[0053] All individual values ​​from it: Mean × number of measured values ​​n with standard deviation s. The values ​​for aged and unaged samples are compared and a factor is determined which expresses the change in shear strength after aging. Appendix: Determination of the instant bond strength for the test adhesive tape on steel1. Test material / air conditioning Sample: at least 4 hours Roll goods: at least 24 hours Air conditioning: 23 ± 2°C and 50 ± 5% relative humidity RT 2. Equipment and chemicals

[0054] Tensile testing device with 90° sliding device or magnetic holder, extension strip (paper), special petrol 60 / 95 for plate cleaning (not for glued test plates), test plate made of steel with a width of 50 mm (e.g. AFERA ​​steel from Rocholl). 3. Test parameters Test specimen width: 25 mm (mark clearly if there is a deviation) Test specimen length: 250 mm (tape ends 20 mm = 210 mm) Test speed: Downward 300 mm / min Upwards 300 mm / min Trigger angle: 90° Terminal spacing: 110 mm (upper terminal to test plate) Downward travel: 65 mm Way up: until the tape is completely removed from the test plate is separated Separation distance: 50 mm (=width of the test plate) Hold time: 0 seconds 4. Start of implementation

[0055] The adhesive tape is cut 25 mm wide, lengthwise, and 250 mm long. If the tape is supplied without a release liner, it must be applied to silicone paper before cutting. The cut must be clean and straight (do not store it on silicone paper!). The instant adhesive strength is determined without a waiting period. 5. Examination

[0056] The cover is removed from the side to be tested, and both ends are clamped into the upper clamp of the testing machine, forming a loop (the ends of the adhesive tape are covered with paper in the area of ​​the clamps). This loop is immediately moved onto the horizontally mounted test plate until a contact area of ​​25 mm x 50 mm is created (test plate width is 50 mm). If the adhesive tape does not cover the entire width of the test plate, the clamp spacing must be reduced. As soon as the contact area has been reached, the loop is immediately pulled back up. 6. Result Mean x of the number of measured values ​​n with standard deviation s. Evaluation: F max : Maximum force in [N / 25mm] Detailed description of examplesExample 1: Composite material No. V1-5

[0057] The material of the middle layer consists of: V1-5 % by weight SIS 20-30 Poly(ethylene-co-propylene) 60-80 Additives (such as color pigments, stabilizers, processing aids such as waxes, lubricants) 0-10 Example 2: Composite material No. V1-6

[0058] The material of the middle layer consists of: V1-6 % by weight SIS 30-40 Poly(ethylene-co-propylene) 50-70 Additives (such as color pigments, stabilizers, processing aids such as waxes, lubricants) 0-10 Example 3 (comparative example): Composite No. #129

[0059] The material of the middle layer consists of: #129 % by weight Styrene block copolymers 40-60 mineral oil 20-40 Poly(ethylene-co-propylene) 10-20 Additives (such as color pigments, stabilizers, processing aids such as waxes, lubricants) 0-10 Example 4: Oil resistance test

[0060] The composites of Examples 1-3 were tested for oil resistance using various test fluids according to the test described above. The results are presented in Table 1 below. Table 1: Results of the oil resistance test Test oil Composite material #129 (comparison example) Composite material V1-5 (according to the invention) Composite material V1-6 (according to the invention) almond oil Formation of holes within < 3h No hole formation within 3 hours No hole formation within 3 hours Paraffin oil Formation of holes within < 3h No hole formation within 3 hours No hole formation within 3 hours

[0061] The same test results were also obtained using various commercial cosmetic products as test fluids, which, in addition to the test oils mentioned, also contained the following base oils (sometimes in the form of oil blends): rapeseed oil, palm kernel or coconut oil, avocado oil, sunflower oil, olive oil, shea butter, and / or calendula oil. Example 5: Elastic capacity test

[0062] The composites of Examples 1-3 were tested for their elastic capacity according to the test described above. The results are presented in Table 2 below. Table 2: Results of the elastic capacity test Composite material Elastic capacity [N] #129 5,37 V1-5 11,50 V1-6 9,84 Example 6: Static shear strength test of a composite bonded to an adhesive tape

[0063] The composite materials of Examples 1-3 were tested for their elastic capacity according to the test described above. Diaper tape CP 1 M 50 from Lohmann-Koester was used as the adhesive tape. The results are presented in Table 3 below. Table 3: Results of the statistical shear strength test of a composite bonded joint using an adhesive tape. Composite material Static shear strength [h] # 129; unaged 0,14 # 129; aged 14d@50°C 0,48 # V 1-5; unaged 0,12 # V 1-5; aged 14d@50°C 3,1 The failure pattern differs as follows:

[0064] In reference # 129 (unaged and aged) as well as in the unaged V1-5, the tape shears off the laminate (= adhesive failure).

[0065] In the aged samples # V1-5 (after 14 days), the tape no longer shears away from the laminate. Instead, the laminate splits. This means that the nonwoven fabric tears occur on the laminate and the nonwoven fabric partially splits away from the elastic film. This means that there is no adhesive failure between the tape and the composite surface (= nonwoven fabric), but rather a cohesive failure within the laminate. The adhesion to the composite is so high that it is destroyed. This means that the sample of the composite material #V1-5, whose polymer mixture does not contain any added plasticizers, particularly mineral oils, enables a stable bond between the adhesive tape and the composite material that develops over time. This is expressed by the increase in static shear strength, expressed as a 15.5-fold extension of the time until failure.

[0066] In contrast, composite #129 prevents the tape's adhesive from bonding with the composite over a certain storage period (adhesive failure occurs). The static shear strength only increases by approximately 3.5 times. This is due to the oil components in the formulation of the polymer blend of composite #129. The oil migrates to the adhesive surface.

Claims

[1] An oil-resistant, sheet-like composite material (laminate) consisting of a middle layer and at least one outer layer or layers arranged above and / or below, wherein the outer layer(s) consist of materials selected from nonwoven fabrics and are not attached to the middle layer by means of a separate adhesive, wherein the middle layer has a single-layer structure, and wherein the middle layer consists of a polymer mixture containing a thermoplastic elastomer from the group of styrene / isoprene / styrene triblock copolymers (SIS) in a proportion of 20 to 40% by weight, wherein the SIS triblock copolymer of the middle layer contains less than 10% or less than 1% of diblock components, and further contains a polymer selected from the group of olefinic polymers in a proportion of 50 to 80% by weight, wherein the olefinic polymers are selected from the group of copolymers of ethylene and propylene,and optionally further non-polymeric auxiliaries, and wherein the polymer mixture of the middle layer does not contain any additives of plasticizer(s), in particular mineral oils. [2] Composite material according to claim 1, characterized by that the nonwovens selected for the outer layers are selected from the group of nonwovens bonded by water jet bonding. [3] Composite material according to one of claims 1 or 2, characterized by that the nonwovens selected for the outer layers are selected from the group of single-layer nonwovens. [4] Composite material according to claim 3, characterized by that the fibers of the nonwovens consist of a uniform fiber type or of a mixture of different fiber types. [5] Composite material according to one of claims 1 to 4, characterized bythat the middle layer has a thickness of 100 micrometers or less, or in the range between 20 and 100 micrometers, or in the range between 20 and 70 micrometers. [6] Composite material according to one of claims 1 to 5, characterized by that a total of two outer layers are connected to the middle layer, one being placed above and the other below the middle layer. [7] Composite material according to one of claims 1 to 6, characterized by that the static shear strength of a bond between an adhesive tape and the nonwoven layer of the outer layer increases by more than ten times, or more than twelve times, when the bond is aged for fourteen days at 50 °C. [8] Composite material according to one of claims 1 to 7, characterized by that the elastic capacity is greater than 9 N / 100 mm. [9] A process for producing a composite material according to any one of claims 1 to 8, characterized bythat the middle layer is applied to or inserted between the outer layer(s) by extrusion lamination.