Waterproof breathable multilayer material

Abstract

A water-resistant, air-permeable multilayer material that allows moisture transfer to prevent moisture accumulation and maintains its resistance to liquid water penetration when the inner surface of the multilayer material is exposed to surface tension reducing substances, the multilayer material comprising: a flexible textile layer, and at least one ultra high molecular weight polyethylene (UHMWPE) porous film, the present invention relates to a porous membrane disposed to block liquid water permeation and permit moisture to permeate through the porous membrane having a moisture transmission rate of more than 4,000-20,000 g / m2 * 24 h and a front water inlet contact angle of more than 90 degrees. The porous membrane has a thickness from 5 microns to 500 microns, a porosity of at least 50%, and an average pore size of less than 1.0 microns. The porous film forms a barrier to prevent surface tension reducing substances from passing through and from entering the textile layer.

Description

TECHNICAL FIELD

[0001] The present utility model relates to a waterproof and breathable multi-layer material designed specifically for outdoor activities. This multi-layer material aims to effectively prevent water from entering the space it needs to protect, while allowing gas or moisture to pass through the multi-layer material, thereby achieving a breathable effect. Through this design, the multi-layer material not only has waterproof function, but also has excellent breathability, which can not only prevent rain or moisture from penetrating from the external environment, but also ensure the comfort of the wearer through gas exchange. TECHNICAL BACKGROUND

[0002] There are some limitations in the waterproof and breathable multi-layer material technology on the market. For example, made of expanded polytetrafluoroethylene (PTFE), is widely used in outdoor clothing and equipment, and is known for its excellent breathability, durability and waterproof performance. However, PTFE has a big problem in environmental friendliness. A large amount of harmful chemicals are used in its production process, which will have a negative impact on the environment. In addition, PTFE itself is not biodegradable, and the finished product will cause long-term environmental pollution after being discarded. With the increasing awareness of environmental protection around the world, consumers' demand for environmentally friendly products is growing, so there is an urgent need for a superior and more environmentally friendly alternative multi-layer material.

[0003] Although there are some alternative technologies to PTFE on the market, these technologies still cannot completely replace PTFE in terms of performance. For example, The North Face's nanospun technology uses a polyurethane (PU) solution coating to make a waterproof multi-layer material. This method provides some breathability, but because polyurethane is hydrophilic, it can absorb water over time, reducing its waterproof performance and affecting the overall performance of the multi-layer material. Similarly, Shi eld is also a multi-layer material that uses a polyurethane solution coating, and its performance is similar to The North Face, although it has waterproof ability, but poor breathability, and durability is far inferior to

[0004] Therefore, the market urgently needs a new type of waterproof and breathable film multi-layer material that not only can match or even surpass Gore-Tex in terms of breathability and durability, but also should have excellent environmental performance. This new multi-layer material must effectively block the penetration of liquid water while maintaining high moisture vapor transmission rate, and be able to withstand long-term wear and tear in outdoor environments, thereby meeting the demand for waterproof, breathable and durable multi-layer materials for outdoor activities. SUMMARY

[0005] The technical advantage of the utility model lies in providing an environmental protection type multilayer material which has excellent waterproof performance and high air permeability. The multilayer material combines at least one porous polyolefin (especially ultra-high molecular weight polyethylene, UHMWPE) with other multilayer material layers to create a multilayer material which can block liquid water penetration while allowing moisture to pass through. Compared with traditional films, the porosity of the porous polyolefin layer in the utility model is as high as 50% or more, and the pore size is less than 1.0 microns. This fine microporous structure not only effectively prevents water from entering, but also provides excellent moisture permeability, thereby maintaining the comfort of the wearer in harsh environmental conditions.

[0006] Specifically, the utility model provides a waterproof and breathable multilayer material which allows moisture transfer to prevent moisture accumulation and still maintains its resistance to liquid water penetration when the inner surface of the multilayer material is exposed to a surface tension reducing substance, the multilayer material comprising:

[0007] a flexible textile layer; and

[0008] at least one layer of ultra-high molecular weight polyethylene (UHMWPE) porous film arranged to block liquid water penetration and allow moisture to pass through the porous film, which has a moisture permeability of more than 4,000-20,000 g / m 2 · 24h and an advancing water contact angle of more than 90 degrees.

[0009] The thickness of the porous film is 5 microns to 500 microns, the porosity is at least 50%, and the average pore size is less than 1.0 microns, the porous film forms a barrier to prevent the passage of surface tension reducing substances and their entry into the textile layer.

[0010] According to one embodiment, the porosity of the porous film is between 50% and 90%, the average pore size is 30 nanometers to 500 nanometers, and the elongation is 10% to 200%.

[0011] According to one embodiment, the textile layer is laminated with at least one layer of the porous film, and the textile layer is made of synthetic fibers, natural fibers or a mixture thereof.

[0012] According to one embodiment, the multilayer structure is combined by an adhesive layer, and the adhesive is polyurethane (PU) or an acrylic-based adhesive.

[0013] According to one embodiment, a plurality of the porous films are combined by an adhesive to form a multilayer structure.

[0014] According to one embodiment, the moisture permeability of the multilayer material is 10,000 g / m 2 / 24 hours.

[0015] ​According to one embodiment, the multi-layered fabric is capable of withstanding water pressure of 5000 to 10000 mm of water column.

[0016] According to one embodiment, the multi-layered fabric is suitable for manufacturing waterproof and breathable outdoor clothing, tents or other protective equipment.

[0017] In addition, the melt index of the UHMWPE multi-layered fabric is close to zero, which endows the multi-layered fabric with excellent durability and mechanical strength, and the multi-layered fabric can withstand wear and tear in outdoor environments for a long time. At the same time, the production process of the polyolefin multi-layered fabric is more environmentally friendly, does not involve the use of harmful chemicals, and the multi-layered fabric itself has better biodegradability. Compared with the traditional PTFE multi-layered fabric, the utility model has a significant improvement in environmental friendliness. Therefore, the utility model not only meets the high requirements of waterproof and breathable performance, but also responds to the market demand for sustainable development and environmentally friendly multi-layered fabric, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to better understand the purpose, technical scheme and advantages of the utility model, the embodiments of the utility model will be described in detail below in combination with the drawings, in which:

[0019] Figure 1A The layered structure of the waterproof and breathable multi-layered fabric of the utility model is shown. The figure shows that the multi-layered fabric is composed of a fiber cloth and an ultra-high molecular weight polyethylene (UHMWPE) and specifically includes a porous ultra-high molecular weight polyethylene (UHMWPE) layer and a multi-layered fabric made of synthetic fibers, natural fibers or mixed fibers thereof;

[0020] Figure 1B The layered structure of the waterproof and breathable multi-layered fabric of the utility model is shown, which shows the SEM cross-sectional view of the porous ultra-high molecular weight polyethylene (UHMWPE) layer with different porosities; and

[0021] Figure 2 Data related to the technical parameters of the porous ultra-high molecular weight polyethylene (UHMWPE) layer in the utility model are shown. DETAILED DESCRIPTION

[0022] The specific embodiments of the utility model are described in detail below in combination with the drawings, so that those skilled in the art can better understand and implement the utility model.

[0023] The utility model relates to a kind of ultra-high molecular weight polyethylene (UHMWPE) porous membrane, it is applied to waterproof and breathable textile cloth, especially in waterproof clothing and shoes and other outdoor equipment.UHMWPE membrane as the ideal substitute of micro-porous polytetrafluoroethylene (PTFE) iron fluorine long membrane, provides excellent waterproof and breathable function.Compared with traditional multilayer material, UHMWPE membrane has significant advantages in environmental protection performance, and shows superiority in high strength, durability.It can be used in harsh outdoor environment for a long time, while maintaining its waterproof and breathability.Through laminating technology, UHMWPE membrane and textile multilayer material are combined to form multilayer composite multilayer material, can significantly enhance the durability and comfort of clothing.In addition, the application of UHMWPE membrane ensures that the comfort of wearer is maintained in adverse weather conditions, and external moisture cannot penetrate.

[0024] The key parameters of UHMWPE membrane are crucial for achieving ideal waterproof and breathable effect.According to the utility model, the pore size of the membrane is less than 1 micrometer, preferably in the range of 30 to 500 nanometers, the porosity is 50% to 90%, the thickness is between 5 to 500 micrometers, and the elongation rate is 10% to 200%.These parameters enable the membrane to provide sufficient waterproof performance while maintaining excellent breathability and mechanical strength, which can be advantageously applied in clothing and footwear.The high porosity of the membrane ensures that moisture can be quickly discharged, preventing internal moisture accumulation from causing discomfort, while its small pore size effectively blocks the penetration of liquid water. Figure 2 Then a data table related to the technical parameters of porous UHMWPE membrane is provided.The table lists parameters such as average pore size, weight of the membrane and bubble point.These values are directly related to the performance indicators of the invention, demonstrating how to optimize waterproof and breathable effect by adjusting pore size and membrane thickness, while ensuring mechanical strength and durability.

[0025] The micro-porous structure of UHMWPE membrane has a bi-continuous porous structure, which ensures its excellent waterproof and breathable performance.Liquid water cannot pass through the micro-pores of the membrane, while gas and moisture can smoothly pass through the membrane layer, ensuring waterproof while maintaining breathability.This structure also enhances the mechanical properties of the membrane, making it have good tear resistance and tensile strength, and can provide long-term protection in outdoor clothing and footwear.At the same time, the chemical stability of UHMWPE membrane enables it to resist the erosion of external chemical substances, further enhancing its durability.

[0026] According to the utility model, the microporous structure of the UHMWPE film is formed by a thermal phase separation process. This process precisely adjusts the structure, pore size, porosity, and thickness of the film by controlling temperature, draw ratio, solid content, and the properties and composition of the polymer multilayer material. By adjusting these parameters, the film can achieve a balance between waterproofing and breathability, meeting different application requirements. The mechanical strength, flexibility, and durability of the film can also be improved through optimization of these processes, facilitating widespread application in outdoor equipment.

[0027] In terms of quantitative performance, the UHMWPE film of the utility model exhibits excellent breathability, with a moisture vapor transmission rate (WVP) preferably exceeding 30 mg / cm 2 -h, which means that while providing waterproof protection, the UHMWPE film can quickly expel moisture, keeping the wearer dry. In addition, the mechanical strength of the UHMWPE film of the utility model makes it suitable for long-term use in harsh outdoor conditions, with excellent durability. The UHMWPE film also exhibits excellent chemical resistance, effectively resisting the erosion of water, oil, and various chemicals, thereby ensuring its long service life in outdoor equipment. Through these advantages, the UHMWPE film becomes an ideal waterproof and breathable multilayer material, suitable for application in clothing, footwear, and other outdoor equipment.

[0028] According to one embodiment, the utility model provides a waterproof multilayer material designed specifically for outdoor activities, which is intended to effectively prevent moisture from entering the space it needs to protect, while allowing gas or moisture to pass through the multilayer material, thereby achieving breathability. Through this design, the multilayer material has both waterproof and excellent breathability, allowing it to prevent rain or moisture from the external environment from penetrating, while ensuring the comfort of the wearer through gas exchange. Figure 1B The structure of the UHMWPE porous film in the waterproof and breathable multilayer material of the utility model is shown. The figure illustrates that this layer is uniformly distributed with micropores, contributing to excellent breathability and moisture permeability. The UHMWPE layer ensures the waterproof and breathable performance of the multilayer material through its microporous structure, while the textile layer provides additional mechanical strength and durability. Figure 1A The close combination of the UHMWPE film and the textile layer is vividly shown, forming a multilayer structure that can prevent liquid water from penetrating and allow moisture to pass through.

[0029] The structure of the multilayer material includes at least one porous polyolefin layer. Polyolefins are a class of polymers with the general formula (CH2CHR)n, where R can be an alkyl group or a hydrogen atom. Polyolefins are generally derived from a few simple olefins, such as ethylene and propylene, with polyethylene (PE) and polypropylene (PP) being the most dominant in commercial applications. In the present invention, the polyolefin used is ultra-high molecular weight polyethylene (UHMWPE) as described above, which has a melt flow rate (MFR) close to zero. This extremely low melt flow rate gives the multilayer material unique physical properties, including high strength and excellent durability, making it suitable for applications that require long-term exposure to harsh environments. This microporous structure allows moisture and other gases to pass freely while preventing water from penetrating, thus providing the multilayer material with air permeability. This microstructure design ensures the dual function of the multilayer material, i.e., the balance between water resistance and air permeability, making it very suitable for outdoor activities such as hiking, camping, and backpacking, which require long-term exposure to changing weather conditions.

[0030] In addition, the layered product can also include at least one layer of a multilayer material made of synthetic fibers, natural fibers, or a mixture of both. These fibrous multilayer materials can be selected according to the desired hand, elasticity, and abrasion resistance. To further enhance the physical properties of the multilayer material, the multilayer material layer can be coated with various chemical coatings, such as anti-fouling, abrasion-resistant, or UV-resistant coatings, thereby increasing its durability and practicality in various environmental conditions.

[0031] To prepare a UHMWPE solution film, it is necessary to start with a homogeneous solution. However, as the molecular weight of UHMWPE increases, the viscosity of the solvent decreases, and the concentration of the solution increases, it becomes more difficult to continuously produce a homogeneous solution. It is easier to dissolve UHMWPE using a high-viscosity solvent, such as paraffin oil or mineral oil, compared to a low-viscosity solvent. According to prior art, high-viscosity solvents are typically used to dissolve UHMWPE. However, until recently, a continuous dissolution process using a low-viscosity solvent was not achieved. Through certain processes of the prior art, UHMWPE can be continuously dissolved in a low-viscosity solvent with a viscosity of less than 5 mPa.s and processed into a film in an extruder. The advantage of this process is that the solution can be prepared and directly extruded into a film or other form in one continuous operation. Nevertheless, other prepared solutions can also be processed into microporous films through similar methods.

[0032] The dissolution temperature refers to the temperature at which UHMWPE can be uniformly dissolved in the solvent, and when the solution cools below this temperature, gelation occurs. In the present invention, by controlling the difference between the dissolution temperature and the gelation temperature, the solvent is removed from the film below the gelation temperature, ensuring process stability. Ultra-high molecular weight polyethylene (UHMWPE) refers to a polymer with a molecular weight of at least 4 x 10 5kg / kmol, preferably at least 8 x 10 5 kg / kmol. Higher molecular weight confers excellent physical and mechanical properties to the film, especially its high porosity and strength, but also increases the difficulty of processing. Generally, the processing becomes more complex when the molecular weight of the polyethylene exceeds 1.5 x 10 6 kg / mol, although in principle the process can be used with higher molecular weight polyethylene. The molecular weight of UHMWPE can be determined by gel permeation chromatography or light scattering.

[0033] The UHMWPE used in the present application is preferably 1.5 x 10 6 kg / mol polyethylene, which can be obtained by known preparation methods using transition metal catalysts. The UHMWPE can contain small amounts of other copolymerized olefins, such as propylene, butene, etc., preferably not more than 5%. In addition, it can also be mixed with other polymers, such as polypropylene, polybutene, etc., but the content is preferably not more than 25%. The UHMWPE can also contain conventional additives, such as stabilizers, antioxidants, pigments, fillers, etc.

[0034] The concentration of the UHMWPE solution can vary within a wide range, and a concentration range of 8% to 50% is generally selected. Below 8%, the film is fragile and difficult to process; while above 50%, the solution is difficult to handle, but still applicable in some processes. Therefore, although it is possible to use high concentration solutions, it is generally not recommended. The solution can be prepared into a film by various methods, such as extrusion, spinning or casting. During processing, the solution is rapidly cooled before gelation by temperature control to ensure that the film has sufficient strength and stability for subsequent processing.

[0035] After the film is formed, in order to promote the rapid removal of the solvent, a relatively high temperature is usually maintained to avoid cooling to room temperature or lower. In order to accelerate the removal of the solvent, a heated gas stream (such as air) or reduced pressure treatment can be used. In order to further enhance the performance of the film, a pre-stretching can be applied to the film during solvent removal. Pre-stretching refers to the difference between the forming speed and the conveying speed, and by adjusting the ratio of these speeds, a predetermined stretching ratio can be obtained. During this stretching process, the area of the film increases and the thickness decreases, thereby improving its strength and flexibility.

[0036] During solvent removal, the film will usually shrink. To prevent this shrinkage, the film is clamped in at least one direction in the present application. If the film is clamped in both directions, the only dimension that is reduced is the thickness. Similarly, for tubular films and hollow fiber films, similar methods can be used to prevent shrinkage. In some cases, the film can be further stretched after solvent removal to increase its area and porosity. The thickness of the film will decrease during the stretching process, but its strength must remain high enough to avoid breaking during the stretching process. For a gel film with a thickness of about 1 mm, the maximum achievable area expansion is 70 times, and if a thicker film is used, the area expansion can reach 100 to 120 times.

[0037] Micro-porous films or membrane multilayers have a wide range of applications, such as in the fields of filters and waterproof and breathable multilayers. In addition, the application of the film of the present application in sealing multilayers also has significant advantages, especially in pipe threaded connections. Such a film can be made into a tape-shaped multilayer with the desired width, and after mild uniaxial or biaxial stretching, it has good flexibility and can easily be wound around the threads to form an efficient seal. Compared with traditional sealing multilayers such as polytetrafluoroethylene, the UHMWPE film has the advantages of being non-toxic and environmentally friendly, and will not release harmful substances during decomposition.

[0038] In addition, the film produced by the process of the present application not only has excellent physical and mechanical properties, especially excellent pore structure, but also can greatly reduce solvent residues, ensuring that there are almost no detectable solvent residues in the final product. Such properties make the film suitable for various industrial applications, including filtration, sealing, and waterproof and breathable clothing. Through the process of the present application, not only can efficient film production be achieved, but also the performance and environmental friendliness of the product can be greatly improved.

[0039] The UHMWPE used in the present application has a molecular weight of usually between 4 x 10 5 kg / kmol and 6.0 x 10 6 kg / mol, preferably 1.2 x 10 6kg / kmol polyethylene, imparting excellent physical and mechanical properties to the film. In a preferred embodiment, the porous polyolefin layer has a porosity of at least 50% and an average pore size of 30 to 200 nanometers. This microporous structure allows the passage of moisture and gases while blocking the entry of liquid water, making the multilayer material both waterproof and breathable. The UHMWPE film can be further enhanced in porosity and strength through solvent removal and stretching processes, for example, by applying a pre-stretch to the film during removal, the porosity can be increased to higher levels. This structure imparts the potential for the multilayer material to be widely used in outdoor activities. The layered multilayer material comprises at least one layer of a multilayer material made of synthetic fibers, natural fibers or a mixture thereof, which can be further enhanced in wear resistance and physical properties through chemical coating. The layered structure of the multilayer material can be achieved through various methods, including adhesive lamination, hot pressing and other techniques. These methods ensure the tight bonding of the multilayer multilayer material, thus achieving the desired waterproofness and breathability.

[0040] To achieve the multi-layer structure of the waterproof and breathable multilayer material, the present application adopts a variety of combined processes, mainly including adhesive lamination method, hot pressing method, etc. These processes ensure that the multilayer multilayer material is firmly combined without affecting its waterproofness and breathability, forming a durable composite multilayer material.

[0041] The adhesive lamination method is a process that combines different layers of multilayer material by applying adhesive between the layers. First, a layer of porous ultra-high molecular weight polyethylene (UHMWPE) film is aligned with the multilayer material layer, and then a layer of adhesive is uniformly coated between the two layers. Common adhesives include polyurethane (PU) or acrylic-based adhesives. These adhesives have good adhesive strength after heating and do not affect the breathability and waterproofness of the UHMWPE film after curing. After the adhesive is applied, the layers of multilayer material are pressed together by a roller device to ensure that the layers are tightly bonded and maintain stable bonding force during the curing process.

[0042] In addition, the hot pressing lamination method combines the porous UHMWPE layer with the multilayer material layer under certain temperature and pressure. This method is usually used in structures that do not require the addition of adhesive to avoid possible negative effects on the breathability of the multilayer material. First, the multilayer material and the porous UHMWPE layer are placed in a lamination device that provides a temperature range of 100°C to 200°C through heated platens while applying a certain pressure (e.g. 1 to 10 megapascals). Under such conditions, a strong bonding force is generated between the UHMWPE layer and the multilayer material layer, forming a stable composite multilayer material. The hot pressing time usually varies from 10 seconds to several minutes, depending on the thickness of the multilayer material used and the heating temperature.

[0043] After the completion of the lamination process, the multi-layer material is subjected to cooling and setting treatment to ensure the stability of the interlayer bonding and prevent delamination or peeling of the film during subsequent use. The multi-layer material should be kept under tension during cooling to avoid wrinkles or deformation during cooling and shrinkage. The set composite multi-layer material can be cut into shapes and sizes suitable for making outdoor clothing, tents and other products according to specific application requirements. Through these processing techniques, the multi-layer material of the present application can provide excellent waterproofness, good air permeability, durability and comfort while maintaining excellent waterproofness, and is suitable for making clothing and equipment in various outdoor activity scenarios.

[0044] By controlling the porosity of the UHMWPE layer and the overall structure of the multi-layer material, the multi-layer material of the present application can provide excellent air permeability under different use conditions. The moisture vapor transmission rate (MVTR) varies in the range of 4,000 to 20,000 g / m 2 / 24 hours, depending on factors such as ambient temperature, humidity and applied pressure.

[0045] In order to evaluate the waterproofness of the multi-layer material, the present application defines the water pressure resistance of each layer of the multi-layer material and the overall water pressure resistance of the combined layers. Tests show that a single layer of porous polyolefin multi-layer material can withstand a water pressure of at least 5000 mm of water column, and after being combined with other multi-layer material layers, the overall multi-layer material can improve the waterproof performance to 10000 mm of water column or higher. This high water pressure resistance ensures the waterproofness of the multi-layer material under extreme weather conditions.

[0046] Although the above description has disclosed the present application in a more specific embodiment, it should be understood that these are only examples and are not intended to limit the scope of the present application. Various changes and improvements can be made by those skilled in the art without departing from the spirit and scope of the present application, and these changes and improvements shall belong to the protection scope of the present application.

Claims

1. A waterproof and breathable multi-layer material, said material allowing moisture transfer to prevent moisture accumulation and maintaining its resistance to liquid water penetration when the inner surface of the multi-layer material is exposed to a surface tension reducing substance, said material comprising: a flexible textile layer; and at least one layer of a porous membrane of ultra-high molecular weight polyethylene (UHMWPE) arranged to block the penetration of liquid water and to allow the penetration of moisture through the porous membrane, having a weight of more than 4,000 - 20,000 g / m 2 • a moisture vapor transmission rate of 24 h and an advancing water contact angle of more than 90 degrees; characterized in that said porous membrane has a thickness of 5 to 500 microns, a porosity of at least 50% and an average pore size of less than 1.0 micron, said porous membrane forms a barrier to prevent the passage of the surface tension reducing substance and its entry into said textile layer.

2. The waterproof, breathable, multi-layered material of claim 1, wherein, said porous membrane has a porosity of between 50% and 90%, an average pore size of between 30 nm and 500 nm and has an elongation of between 10% and 200%.

3. The waterproof, breathable, multi-layered material of claim 1, wherein said textile layer is laminated with at least one layer of said porous membrane, said textile layer is made of synthetic fibers, natural fibers or a mixture thereof.

4. The waterproof, breathable, multi-layered material of claim 1, wherein, a plurality of said porous membranes are bonded by an adhesive to form a multi-layer structure.

5. The waterproof, vapor-permeable, multilayer material according to claim 4, characterized in that, said adhesive is a polyurethane (PU) or an acrylic based adhesive.

6. The waterproof, vapor-permeable, multilayer material according to claim 1, characterized in that, The moisture vapor transmission rate of the multilayered material is 10,000 g / m 2 / 24 hours.

7. The waterproof, breathable, multi-layered material of claim 1, wherein, the combined structure of said multi-layer material is capable of withstanding a water pressure of between 5000 and 10000 mm of water column.

8. The waterproof and breathable multilayer material according to any one of claims 1 to 7, characterized in that, said multi-layer material is suitable for the manufacture of waterproof and breathable outdoor clothing or tents.

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