Multilayer composite material including skeleton membrane

Abstract

The present invention relates to a multilayer composite material, comprising a first monolayer and a second monolayer, and a third polymer film located between the first monolayer and the second monolayer, wherein the first monolayer comprises a first matrix material and high-performance fibers arranged in a first direction, the second monolayer comprises a second matrix material and high-performance fibers arranged in a second direction, and the third polymer film has a tensile modulus of at least 0.75 GPa measured by ASTM D882. Preferably, the high-performance fibers comprise UHMWPE fibers. Thermoplastic polyurethane is in contact with the first monolayer to form a first outer layer of the composite material, and is in contact with the second monolayer to form a second outer layer of the composite material opposite to the first outer layer. The present invention further relates to the use of the multilayer composite material in backpacks, bags, sacks, medical equipment, outdoor products, canvas, tents, tarps, shelters, clothing, ponchos, severe weather equipment, mats, coats, jackets, sleeping bags, lifting bags, parachutes, large kites, inflatable structures, beams, balloons, back rafts, inflatable equipment, life rafts, inflatable sculptures, airships (High Altitude Airship, HAA), space applications, flexible circuits, footwear and umbrellas.

Description

[0001] The present invention relates to a multilayer composite material, comprising: a first single layer, which comprises a first matrix material and high-performance fibers arranged along a first direction; and a second single layer, which comprises a second matrix material and high-performance fibers arranged along a second direction. The present invention also relates to the use of the multilayer composite material in different applications.

[0002] The prior art knows such a multilayer composite material, which comprises: a first single layer, which comprises a first matrix material and high-performance fibers arranged in a first direction; and a second single layer, which comprises a second matrix material and high-performance fibers arranged in a second direction. Such a multilayer composite material is disclosed, for example, in US2016023428. In addition, these composite materials may include an outer layer on both sides of the composite material. The outer layer may be a film such as a polyurethane film. The disadvantage of these multilayer composite materials including a polyurethane outer layer film is that they provide significantly lower tensile strength and shear properties than one would expect for a particular amount of fiber reinforcement in the composite material.

[0003] It is therefore an object of the present invention to provide a lightweight multilayer composite material having improved mechanical properties.

[0004] Another object of the present invention is to provide a lightweight multilayer composite material having improved tensile strength.

[0005] Another object of the present invention is to provide a lightweight multilayer composite material having improved shear strength.

[0006] The objects of the present invention have been achieved by a multilayer composite material, comprising: a first single layer, the first single layer comprising a first matrix material and high-performance fibers arranged along a first direction; and a second single layer, the second single layer comprising a second matrix material and high-performance fibers arranged along a second direction; an inner polymer film, the inner polymer film being located between the first single layer and the second single layer, wherein the tensile modulus of the inner polymer film measured by ASTM D882 is at least 0.75 GPa.

[0007] Surprisingly, it was found that the inner polymer film between the first monolayer and the second monolayer provides a multilayer composite material with improved tensile strength. This is surprising because the tensile load of the composite material is mainly borne by the high-performance fibers, and the increase in tensile strength exceeds the tensile strength contribution of the inner polymer film. In addition, it has been found that the multilayer composite material comprising the inner polymer film shows improved lap shear seam strength. It is also found that the inner polymer film can improve the load distribution performance of the multilayer composite material. The film essentially creates a "skeleton" for the composite material, and although the "skeleton film" is fragile / low in strength, the resulting composite material has a higher strength than the material without the "skeleton".

[0008] The inner polymer film has a tensile modulus of at least 0.75 GPa as measured by ASTM D882. Preferably, the inner polymer film has a tensile modulus of 2 GPa. More preferably, its tensile modulus is at least 4 GPa, and even more preferably, the tensile modulus is at least 6 GPa.

[0009] The inner polymer film or skeleton film is preferably selected from polyester film, polyethylene film, polyamide film or polyvinyl fluoride film. Preferably, the inner film is selected from polyester film. More preferably, the polyester is selected from polyethylene terephthalate (PET) or polyethylene naphtalate (PEN). The inner polymer film preferably has a thickness of 1 μm to 100 μm, preferably 2-50 μm, more preferably 3-40 μm.

[0010] The inner polymer film or skeleton membrane can be in the form of weaving or nonwoven fabric. Preferably, the inner film is in the form of nonwoven fabric. The nonwoven fabric preferably comprises at least one or its mixture in carbon fiber, polyethylene fiber, polyamide fiber or polyester fiber. The nonwoven fabric more preferably comprises carbon fiber, because these fibers increase the rigidity of the multilayer composite material.

[0011] In another embodiment, the inner membrane may be a waterproof and / or (non) breathable membrane.

[0012] In a further preferred embodiment, the inner polymer film may be a waterproof / breathable (W / B) film. W / B films act as a barrier layer, allowing gases (including water vapor) to be transmitted through the material, but not allowing liquid water to be transmitted. Such films include those sold under the trade name and ECTFE and EPTFE, polyamide, polyester, PVF, PEN, specially designed UHMWPE films such as Film and microporous polypropylene film.

[0013] A specific embodiment of the W / B membrane of the present invention may be in the form of a woven fabric, which may be coated or (partially) impregnated with a matrix material to allow it to have W / B properties.

[0014] Another specific embodiment of the W / B membrane of the present invention may be in the form of a non-woven fabric, which may be coated or (partially) impregnated with a base material to give it W / B properties. Typical examples of non-woven fabrics include felt.

[0015] The first and second monolayers of the multilayer composite material of the present invention comprise high performance fibers, wherein the first layer comprises a first matrix material and high performance fibers arranged in parallel directions, and the second layer comprises a second matrix material and high performance fibers arranged in parallel directions. The second fiber direction is preferably offset by up to 90 degrees relative to the first fiber direction. The high performance fibers in the first and second layers may be the same or different.

[0016] The first monolayer and the second monolayer may also be referred to as unidirectional (UD) layers. The multilayer composite may include one or more additional monolayers bonded thereto to form a stack. In this way, many monolayers may be used and the fiber direction may never repeat, or several monolayers may be offset from each other until at some point the fiber direction in a layer repeats with a monolayer further down in the stack.

[0017] The first matrix material and the second matrix material can be selected from: polyacrylate; polyurethane, such as Hysol US0028; polyester, such as thiol Adcote; polysiloxane, such as DOW-96-083, DOW-X3-6930, DOW-6858 (UV curable); polyolefin; modified polyolefin; ethylene copolymer, such as ethylene vinyl acetate; polyamide; polypropylene or thermoplastics, such as PEEK, PPS, Radel, Ryton.

[0018] Preferably, the matrix material comprises polyurethane. The polyurethane may comprise polyether-urethane or polyester-urethane based on polyether diols. The polyurethane is preferably based on aliphatic diisocyanates, as this further improves the product properties.

[0019] In a further preferred embodiment, the matrix material may include an acrylic-based resin or a polymer comprising acrylate groups.

[0020] In the case of polyolefins, the matrix material preferably comprises a homopolymer or copolymer of ethylene and / or propylene, wherein the density of the polymer resin measured according to ISO 1183 is 860 kg / m 3 Up to 930kg / m 3 , the peak melting temperature ranges from 40° to 140°C and the heat of fusion is at least 5 J / g.

[0021] Further details of single layers with unidirectional fibers and matrix materials can be found, for example, in US5470632, the entirety of which is incorporated herein by reference.

[0022] The amount of matrix material in the first or second monolayer is typically 10 to 95 wt %; preferably 20 to 90 wt %, more preferably 30 to 85 wt %, and most preferably 35 to 80 wt %. This ensures sufficient bonding strength between the monolayer and other components, thereby reducing the chance of premature delamination of the composite material after repeated bending cycles.

[0023] The high performance fibers used for the first and second monolayers typically have a tensile strength of at least 0.5 GPa, preferably at least 0.6 GPa, more preferably at least 0.8 GPa. In a preferred embodiment, the strength of the fibers, preferably polyethylene fibers, is at least 3.0 GPa, preferably at least 3.5 GPa, more preferably at least 4.0 GPa, and most preferably at least 4.5 GPa. For economic reasons, the strength of the fibers is preferably less than 5.5 GPa. The tensile strength of the fibers is preferably 3.1 GPa-4.9 GPa, more preferably 3.2 GPa-4.7 GPa, and most preferably 3.3 GPa-4.5 GPa.

[0024] The amount of fibers in a single layer is typically between 1 and 50 g / m2. The amount of fibers may also be referred to as the fiber density of the layer. Preferably, the amount of fibers in a single layer is 2-30 g / m2, more preferably 3-20 g / m2. It has been found that fiber densities within these ranges help maintain the flexibility of the multilayer composite material.

[0025] Fibers suitable for use in the multilayer composite material of the present invention include, for example, fibers based on the following polymers: polyamides, such as polyamide 6 or polyamide 6.6; polyesters, such as polyethylene terephthalate; or polyolefins, such as polypropylene or polyethylene. Other preferred fibers include: aromatic polyamide fibers (also often referred to as aramid fibers), especially poly(terephthalamide); liquid crystal polymers and ladder polymer fibers, such as polybenzimidazoles or polybenzoxazoles, such as poly(1,4-phenylene-2,6-benzobisoxazole) (1,4-phenylene-2,6-benzobisoxazole, PBO) or poly(2,6-diimidazole [4,5-b-4',5'-e] pyridinyl-1,4-(2,5-dihydroxy)phenylene) (PIPD; also known as M5); polyaryletherketones, including polyetheretherketone; and fibers such as highly oriented polyolefins, polyvinyl alcohol and polyacrylonitrile, which are obtained, for example, by a gel spinning process. Preferably, highly oriented polyolefin, aramid, PBO and PIPD fibers or a combination of at least two thereof are used.The highly oriented polyolefin fibers include polypropylene fibers or polyethylene fibers and have a tensile strength of at least 1.5 GPa.

[0026] Most preferred are high performance polyethylene fibers, also called highly drawn or oriented polyethylene fibers, consisting of polyethylene filaments prepared by a gel spinning process, such as described in, for example, GB 2042414 A or WO 01 / 73173. The advantage of these fibers is that they have a very high tensile strength and are light weight, so that they are suitable for use in very thin layers. Preferably, ultra high molecular weight polyethylene (UHMWPE) fibers having an intrinsic viscosity of at least 4 dl / g, more preferably an intrinsic viscosity of at least 8 dl / g, are used.

[0027] In various embodiments, the multilayer composite material comprising the first monolayer and the second monolayer and optionally other monolayers may further include at least a first polymer film and a second polymer film, wherein the first polymer film and the second polymer film are in contact with the first monolayer and the second monolayer to form the outer layer of the multilayer composite material. In this way, the stack of the first monolayer, the second monolayer and the inner polymer film constitutes the core of the multilayer composite material, and the first polymer film and the second polymer film are exposed as two outer layers.

[0028] The first polymer film and the second polymer film may include, for example: a polyolefin film, such as a linear low-density polyethylene film, a polypropylene film; a polyurethane film; or a polyester film. The first polymer film and the second polymer film may be the same film or different films. Preferably, the first polymer film and the second polymer film are polyurethane films.

[0029] In a more preferred embodiment, the first outer polymer film and the second outer polymer film are biaxially stretched polyolefin or polyester films, examples of which are biaxially stretched high density polyethylene films, biaxially stretched polypropylene films or biaxially stretched PET films or PEN films.

[0030] The invention also relates to a method for manufacturing a multilayer composite material by stacking at least a first monolayer and a second monolayer, the first monolayer comprising parallel arranged fibers and a first matrix material, the second monolayer comprising parallel arranged fibers and a second matrix material, and the inner polymer film is located between the first monolayer and the second monolayer, the assembly having two outer surfaces, the two outer surfaces comprising the first polymer film and the second polymer film, wherein the assembly is pressed at an absolute pressure of 1.05 bar to 5 bar, preferably 1.1 bar to 4 bar, more preferably 1.2 bar to 3 bar. Compression under these conditions is done in a static press (including an autoclave). Preferably, a continuous press is used in the form of a calender or a continuous belt press. The temperature during pressing is preferably between 35°C and 120°C. More preferably, the temperature during pressing is between 40°C and 100°C, and most preferably, the temperature during pressing is between 45°C and 90°C. Pressing is carried out at a pressure of 1 to 5 bar and a temperature of 35 to 120°C. The duration of the pressure and temperature treatment will vary depending on the intended end use and can be optimized by simple trial and error experiments.

[0031] In one specific form of the method for making a multilayer composite material, at least one of the first polymer film surface and the second polymer film surface of the composite material is in contact with a covering, preferably a removable covering, during the pressure and temperature treatment. The covering can be a glass fiber reinforced PTFE sheet, or can be a steel belt, for example in a continuous belt press, optionally with a release layer, for example in the form of siliconized paper. Alternative forms of such removable coverings include soft materials based on rubber. The Shore A value of the rubber is less than 95, more preferably less than 80, and preferably at least 50, as determined by the Durometer test according to ISO 7619.

[0032] The first and second monolayers may be obtained by orienting a plurality of fibers in a parallel manner in one plane, for example by pulling a plurality of fibers or yarns from a fiber bobbin holder onto a comb and impregnating the fibers with a matrix material in a manner known to a person skilled in the art before, during or after orientation. In this process, the fibers may have been provided with at least one finish having at least one component or polymer different from the plastic matrix material, for example to protect the fibers during treatment or to make the fibers adhere better to the plastic of the monolayer. The fibers may be surface treated before finishing or before the fibers are brought into contact with the matrix material. Such treatment may include treatment with a chemical agent, such as an oxidizing agent or an etching agent, but preferably includes a plasma or corona treatment.

[0033] To further fine-tune the properties of the multi-layer composite material, a person skilled in the art may decide to add a third single layer and subsequent single layers, up to n single layers, in contact with and rotated relative to the adjacent single layer to offset the fiber direction. In various embodiments, the total number n of single layers may be between about 4 and about 8 (4 < n < 8). Depending on the application, the value of n can be selected to suit a particular application or end use. In the multi-layer composite material according to the present invention, each single layer can be rotated relative to the previous single layer.

[0034] The present invention further relates to the use of the multi-layer composite material of the present invention in the following applications: backpacks, packs, bags, medical equipment, outdoor products, canvas, tents, tarpaulins, shelters, clothing, raincoats, foul weather gear, mats, outerwear, jackets, sleeping bags, lift bags, parachutes, large kites, inflatable structures, beams, balloons, backrafts, inflatable equipment, life rafts, inflatable sculptures, airships (High Altitude Airships, HAA), space applications, flexible circuits, footwear, inflatable devices (radomes), tensile structures or umbrellas.

[0035] result

[0036] Measurement method

[0037] The following are the test methods mentioned herein:

[0038] Tensile strength is measured according to ASTM D3039, where a strip of material with a uniform measurement width is clamped in top and bottom column fixtures and stretched at a rate of 3 inches per minute until failure.

[0039] Tensile modulus is measured by ASTM D882.

[0040] The film thickness determined by the film supplier is measured by a handheld digital micrometer.

[0041] Laminate weight is measured according to ASTM D3776-07, weighing a 12 x 12 inch laminate sample using an analytical balance with a display accuracy of 0.0001 grams. Laminate weight is expressed in grams per square meter (gsm). Examples

[0042] A composite laminate is manufactured, comprising: a first monolayer, the first monolayer comprising high-performance fibers (ultra-high molecular weight polyethylene (UHMWPE)) in a polyurethane (PUR) matrix, oriented in the 0° direction; a second monolayer, the second monolayer comprising UHMWPE fibers in a PUR matrix, oriented in the 90° direction; wherein an internal polymer film is located between the first monolayer and the second monolayer of high-performance fibers; and further optionally comprising a first external polymer film located on the top surface of the laminate and the same second polymer film located on the bottom surface of the laminate. The composite material is cut into target strips 1 inch wide and 26 inches long, with the length parallel to the 0° direction. The actual width of each sample is measured and recorded. Each longitudinal end of the sample is clamped by a column clamp, resulting in a test sample gauge length of 10 inches. The sample is pre-stretched to 5% of the expected laminate failure load by a mechanical test frame. The tensile strength of the sample is tested at a constant extension rate of 3 inches / minute until the sample fails. The maximum tensile load of the sample during the test is recorded and divided by the width of the sample to determine the tensile strength expressed as load / width.

[0043] It is clear from Table 1 that there is a balance between thickness, weight and modulus of the inner polymer film.

[0044] Comparative examples are given in Table 2; multilayer composites without an inner or skeleton membrane.

[0045] Table 1

[0046]

[0047] TPU = Thermoplastic Polyurethane

[0048] PEN = Polyethylene naphthalate

[0049] PET = Polyethylene terephthalate

[0050] Tedlar = Polyvinyl Fluoride

[0051] Table 2: Comparative experiment

[0052]

Claims

1. A multilayer composite material, comprising: a first single layer, the first single layer comprising a first matrix material and high-performance fibers arranged along a first direction, and a second single layer, the second single layer comprising a second matrix material and high-performance fibers arranged in a second direction, and an inner polymer film positioned between the first monolayer and the second monolayer, wherein the inner polymer film has a tensile modulus of at least 0.75 GPa as measured by ASTM D882, The high performance fibers include UHMWPE fibers. The thickness of the inner polymer film is 2 μm-40 μm, And wherein the inner polymer film is selected from polyethylene terephthalate PET, polybutylene terephthalate PBT or polyethylene naphthalate PEN.

2. The multilayer composite material according to claim 1, wherein the high performance fibers of the second single layer are arranged along the second direction and the second direction is offset by at most 90 degrees relative to the high performance fibers of the first single layer arranged along the first direction.

3. The multilayer composite material according to any one of claims 1-2, wherein the inner polymer film is a waterproof and / or (non) breathable film.

4. The multilayer composite material according to claim 1, wherein at least one matrix material is selected from the group consisting of polyacrylates, polyurethanes, polyesters, polysiloxanes, polyolefins, polyamides, and polypropylene.

5. The multilayer composite material according to claim 4, wherein the polyolefin is selected from the group consisting of modified polyolefins and ethylene copolymers.

6. The multilayer composite material according to claim 4 or 5, wherein the first matrix material and the second matrix material comprise polyurethane.

7. The multilayer composite material of claim 1 , wherein the multilayer composite material comprises a first polymer film and a second polymer film, wherein the first polymer film is in contact with the first monolayer to form a first outer layer of the composite material, and wherein the second polymer film is in contact with the second monolayer to form a second outer layer of the composite material, the second outer layer being opposite to the first outer layer.

8. The multilayer composite material of claim 7, wherein the first polymer film and the second polymer film are selected from polyurethane.

9. Use of the multilayer composite material according to any one of claims 1 to 8 in the following applications: bags, sacks, medical equipment, outdoor products, large kites, inflatable structures, beams, space applications, flexible circuits, leather goods, interior decoration.

10. Use of the multilayer composite material according to any one of claims 1 to 8 in the following applications: tarpaulins, clothing, severe weather equipment, inflatable equipment.

11. Use of the multilayer composite material according to any one of claims 1 to 8 in the following application: sportswear.

12. Use of the multilayer composite material according to any one of claims 1 to 8 in backpacks, tents, ponchos, mats, jackets, sleeping bags, lifting bags, parachutes, balloons, back rafts, inflatable sculptures, airships, footwear, luggage, wallets, handbags, gloves.

13. Use of the multilayer composite material according to any one of claims 1 to 8 in the following applications: sails, shelters, jackets, life rafts, high-altitude airships.

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