Poly-methylpentene film, coated molded pulp substrate, and method for producing the same

Abstract

To provide a poly-methylpentene film, a coated molded pulp substrate, and a method for producing the same.SOLUTION: There is provided a poly-methylpentene film, comprising in order: a functional surface layer; a matrix layer; and an adhesive layer. The functional surface layer is formed of a functional material, the matrix layer is formed of a polymeric material, and the adhesive layer is formed of a low-temperature heat-sealable material. The poly-methylpentene film is bonded to a fibrous base layer via the adhesive layer to form a coated molded pulp substrate that can be used to produce a coated molded pulp container. Therefore, the coated molded pulp container has a heat-resistant property, a resistant property to high-temperature oil penetration, a non-stick property to food, a scratch-resistant property, and a highly safe property from a standpoint of food hygiene.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to membranes, coated substrates, and methods of making the same, and more particularly to polymethylpentene membranes, coated molded pulp substrates, and methods of making the same. [Background technology]

[0002] In today's society, where industry and commerce are highly developed, fast food and takeout are widely loved among people due to their busy lifestyles. Restaurants generally serve food and drinks in disposable tableware to provide customers with food quickly, conveniently, and cleanly. As environmental protection continues to gain importance in various countries, the reduction of carbon emissions, the circular economy, biomass renewable energy, biodegradable recycled materials, and the reduction of plastic product use have become global goals that many countries are working toward. As a result, most stores use molded pulp containers (such as paper boxes, paper cups, paper bowls, and paper plates) to hold food and drinks, and these containers are gradually replacing plastic containers.

[0003] Film-coated pulp containers combine the environmentally friendly properties of paper with the waterproof and oil-resistant packaging properties of plastic. They are made by pasting a film of plastic material onto the surface of a paper-plastic container, with the weight of the plastic material accounting for approximately 10% of the container's total weight, substantially achieving the goal of reducing the use of plastic in packaging materials and potentially replacing some of the packaging uses of plastic containers. The film material is related to the properties of the resulting film-coated pulp container, and common film materials include polyethylene, polypropylene, polylactic acid, polyethylene terephthalate, etc. Summary of the Invention [Problem to be solved by the invention]

[0004] The membranes of commercially available coated molded pulp containers are primarily made from a mixture of polyethylene and polypropylene. Paper cups and boxes made from this coated molded pulp base, formed by coating a paper layer with this, have a minimum heat resistance of approximately 70°C. Polylactic acid is biodegradable but lacks durability and heat resistance. On the other hand, polyethylene terephthalate (PET) has properties such as acid resistance, alkali resistance, oil resistance, water resistance, and gas barrier properties, but its heat resistance temperature is only approximately 60°C to 85°C. While coated molded pulp containers made using these membrane materials are waterproof, oil-resistant, and heat-resistant, their heat resistance is often exceeded when storing hot foods, such as freshly boiled hot soup or hot porridge. This raises concerns about the release of plasticizers and the precipitation of decomposition products into the food. Consuming hot foods packaged in this way for extended periods of time can easily lead to the accumulation of harmful substances in the body, posing serious health risks. Therefore, it is important to address the shortcomings of conventional technologies. [Means for solving the problem]

[0005] The objective of the present invention is to provide a polymethylpentene film, a coated molded pulp substrate, and a method for manufacturing the same, which have excellent heat resistance, high-temperature oil penetration resistance, and high food hygiene safety. A coated molded pulp container that can be heated in a microwave or oven is manufactured using environmentally friendly or recycled materials that can replace plastic or reduced-weight plastic. The manufactured coated molded pulp container has excellent heat resistance, high-temperature oil penetration resistance, food non-stick properties, scratch resistance, food hygiene and safety, heat deformation resistance, and freeze resistance, improving the high-temperature oil penetration resistance of conventional coated molded pulp containers and fulfilling the functions required for food packaging. Furthermore, the coated molded pulp container can be used to contain, store, and heat food or liquids, and also solves the problem of hand burns caused by plastic packaging containers at high temperatures. It can replace current plastic containers for instant foods, making it useful as a strategy for reducing plastic consumption in disposable plastic containers. Furthermore, the material from the manufactured coated molded pulp container can be burned in an incinerator to recover heat energy without impairing the incinerator's function.

[0006] One embodiment of the present invention provides a polymethylpentene film comprising: a functional surface layer formed from a functional material, the functional material being polymethylpentene or a blend of polymethylpentene and a polyolefin resin, the polyolefin resin monomer being a C2-C4 olefin molecule, and the polymethylpentene content in the blend being 20% by weight to 99% by weight based on 100% by weight of the total blend; a matrix layer formed on one side of the functional surface layer by co-extrusion and made from a polymeric material, the polymeric material being a thermoplastic polyolefin, an aromatic polymer, a polyamide polymer, a polyethylene copolymer, or a combination thereof; and an adhesive layer formed on the side of the matrix layer away from the functional surface layer by co-extrusion and made from a low-temperature heat-sealable material, the low-temperature heat-sealable material being a metallocene polyolefin, an olefin copolymer, a polyolefin resin, or a combination thereof.

[0007] According to the aforementioned polymethylpentene membrane, the functional material in the functional surface layer has a first melt index, the polymeric material in the matrix layer has a second melt index, and the low-temperature heat-sealable material in the adhesive layer has a third melt index, and the difference between the maximum and minimum values of the first melt index, the second melt index, and the third melt index is less than 20.

[0008] According to the above-mentioned polymethylpentene membrane, in the functional surface layer, the polyolefin resin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, or a combination thereof.

[0009] In the matrix layer of the polymethylpentene membrane, the thermoplastic polyolefin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, polymethylpentene, a thermoplastic elastomer, a polyolefin elastomer, or a combination thereof; the aromatic polymer is polystyrene; the polyamide polymer is polyamide; and the polyethylene copolymer is ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-butyl acrylate copolymer, or a combination thereof.

[0010] According to the above-mentioned polymethylpentene film, in the adhesive layer, the metallocene polyolefin is an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene-α-olefin terpolymer, or a combination thereof, and the olefin copolymer is an ionic copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-butyl acrylate copolymer, or a combination thereof.

[0011] According to the polymethylpentene film, the adhesive layer has an adhesive strength of 20 g or more.

[0012] The polymethylpentene film described above further includes a barrier layer provided between the functional surface layer and the matrix layer or between the matrix layer and the adhesive layer.

[0013] According to the aforementioned polymethylpentene film, the material composition of the barrier layer is ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyamide, polyvinyl alcohol, or a combination thereof.

[0014] Another embodiment of the present invention provides a method for producing a coated pulp substrate, including the steps of: providing the polymethylpentene film described in the previous paragraph; heating the polymethylpentene film to 300°C to 750°C and maintaining the temperature for 2 seconds to 30 seconds to obtain a softened polymethylpentene film; and coating the softened polymethylpentene film to a fiber base layer via an adhesive layer by a coating method to obtain a coated pulp substrate.

[0015] According to the above-mentioned method for producing the coated pulp substrate, the coating method is a vacuum suction method or a hot air blowing method.

[0016] A further embodiment of the present invention provides a coated molded pulp substrate produced by the method for producing a coated molded pulp substrate described in the previous paragraph, wherein the thickness of the fibrous base layer may be 50% or more of the overall thickness of the coated molded pulp substrate. [Brief explanation of the drawings]

[0017] To make the above and other objects, features, advantages and embodiments of the present invention more clearly and comprehensibly, the drawings are described as follows. [Figure 1] FIG. 1 is a schematic diagram illustrating a polymethylpentene membrane according to one embodiment of the present invention. [Figure 2] 3 is a flow chart illustrating steps in a method for making a coated pulp substrate according to another embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram illustrating a coated pulp substrate according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. For clarity, many practical details will be lumped together in the following description. However, it should be recognized that these practical details are not intended to limit the present invention. That is, in some embodiments of the present invention, these practical details are not essential. Furthermore, to simplify the drawings, some conventional structures and components are simply and schematically shown in the drawings, and overlapping components may be represented by the same numerals.

[0019] Referring to FIG. 1, which shows a schematic diagram of a polymethylpentene film 100 according to one embodiment of the present invention, the polymethylpentene film 100 is a multilayer structure formed by coextrusion, and includes a functional surface layer 110, a matrix layer 120, and an adhesive layer 130.

[0020] The functional surface layer 110 is formed of a functional material, which may be polymethylpentene (TPX) or a blend of polymethylpentene and a polyolefin resin, the polyolefin resin monomer being a C2-C4 olefin molecule, and the polymethylpentene content in the blend being 20-99 wt% relative to the total weight of the blend (100 wt%). The polyolefin resin may be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polybutylene (PB), polybutadiene (PB), or a combination thereof. The functional material has a first melt flow index, which may be between 0.5 and 50, preferably between 1 and 30. Polymethylpentene has a melting point of approximately 220°C to 240°C, and its heat resistance is much higher than that of common membrane materials such as polyethylene, polypropylene, polylactic acid (PLA), and polyethylene terephthalate (PET). It also has low surface tension, the ability to repel oily substances, and a lack of viscosity. Because the functional surface layer 110 contains a sufficient amount of polymethylpentene, the functional surface layer 110 is the layer in the polymethylpentene membrane 100 that is most resistant to high-temperature oil, and the thickness of the functional surface layer 110 may be 5 μm to 90 μm.

[0021] The matrix layer 120 is formed on one side of the functional surface layer 110 by coextrusion. The matrix layer 120 is formed of a polymeric material, and the polymeric material may be a thermoplastic polyolefin, an aromatic polymer, a polyamide polymer, a polyethylene copolymer, or a combination thereof. Furthermore, the thermoplastic polyolefin may be polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, polymethylpentene, a thermoplastic elastomer (TPE), a polyolefin elastomer (POE), or a combination thereof. The aromatic polymer may be polystyrene (PS), the polyamide polymer may be polyamide (PA), and the polyethylene copolymer may be ethylene acrylic acid copolymer (EAA), ethylene methacrylic acid copolymer (EMAA), ethylene butyl acrylate copolymer (EBA), or a combination thereof.

[0022] The matrix layer 120 can withstand high temperatures and has adhesive properties with respect to the functional surface layer 110 and the adhesive layer 130, and the functional surface layer 110 and the adhesive layer 130 are adhered to each other via the matrix layer 120 as a polymethylpentene film 100 having a multilayer structure. The matrix layer 120 has a second melt index, which may be between 0.5 and 50, and preferably between 1 and 30. Furthermore, the matrix layer 120 imparts rigidity and toughness, and when filled to a predetermined thickness, imparts vacuum suction resistance to the polymethylpentene film 100, and the thickness of the matrix layer 120 may be between 5 μm and 90 μm.

[0023] Because polymethylpentene has low surface tension, it is difficult to mix with other materials and process, and therefore most membranes made of polymethylpentene are known to have a single-layer structure. The functional material of the functional surface layer 110 of the polymethylpentene membrane 100 of the present invention is polymethylpentene or a blend of polymethylpentene and a polyolefin resin, and by combining the functional surface layer 110 with a matrix layer 120 that has adhesive properties, it can later be manufactured into a multilayer structure.

[0024] The adhesive layer 130 is formed by coextrusion on the surface of the matrix layer 120 away from the functional surface layer 110. The adhesive layer 130 is formed of a low-temperature heat-sealable material, such as a metallocene polyolefin, an olefin copolymer, a polyolefin resin, or a combination thereof. The metallocene polyolefin may be an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene-α-olefin terpolymer, or a combination thereof. The olefin copolymer may be an ionic copolymer, an ethylene-vinyl acetate copolymer (EVA), an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-butyl acrylate copolymer, or a combination thereof. The adhesive layer 130 has a third melt index, which may be between 0.5 and 50, preferably between 1 and 30. The adhesive layer 130 has low-temperature adhesive properties to paper and an adhesive strength of 20 g or more, so that the polymethylpentene film 100 may be bonded to a fabric base layer (not shown) via the adhesive layer 130. The thickness of the adhesive layer 130 may be 5 μm to 90 μm.

[0025] Furthermore, the difference between the maximum and minimum values of the first melt index of the functional material in the functional surface layer 110, the second melt index of the polymeric material in the matrix layer 120, and the third melt index of the low-temperature heat-sealable material in the adhesive layer 130 may be less than 20, so that the materials of the functional surface layer 110, the matrix layer 120, and the adhesive layer 130 have similar flow properties. When the polymethylpentene film 100 is produced by coextrusion, the flow rates between each layer are similar, and the produced polymethylpentene film 100 has excellent quality and appearance.

[0026] Furthermore, the polymethylpentene film 100 may further include a barrier layer (not shown), which is disposed between the functional surface layer 110 and the matrix layer 120 or between the matrix layer 120 and the adhesive layer 130. The material composition of the barrier layer may be ethylene vinyl silane (EVOH), polyvinylidene chloride (PVDC), polyamide (PA), polyvinyl alcohol (PVA), or a combination thereof. The provision of the barrier layer effectively blocks the permeation of gases, particularly oxygen, carbon dioxide, and nitrogen gases. The ethylene content of the ethylene vinyl alcohol copolymer is 27 to 45 mol%. However, the material composition of the barrier layer is merely exemplary and is not limited to these materials; other materials with high gas barrier properties may also be used.

[0027] Furthermore, the number of layers in the matrix layer 120 may be one or more, and the polymethylpentene membrane 100 may be designed with various functions depending on the combination of polymeric materials in the matrix layer 120. This membrane may have a multi-layer structure of four, five, six or more layers, but the present invention is not limited thereto, and the number of layers in the polymethylpentene membrane 100 may be increased or changed according to the needs of use.

[0028] Further, referring to FIG. 2, which shows a process flow chart of a method 200 for manufacturing a coated molded pulp substrate according to another embodiment of the present invention, and FIG. 3, which shows a schematic diagram of a coated molded pulp substrate 300 according to a further embodiment of the present invention, the method 200 for manufacturing a coated molded pulp substrate includes steps 210, 220, and 230.

[0029] Step 210 is to provide a polymethylpentene membrane 310, which includes at least a functional surface layer 311, a matrix layer 312, and an adhesive layer 313. The functional surface layer 311, the matrix layer 312, and the adhesive layer 313 of the coated molded pulp substrate 300 in Fig. 3 are the same as the functional surface layer 110, the matrix layer 120, and the adhesive layer 130 of the polymethylpentene membrane 100 in Fig. 1, so the technical details will not be repeated. In detail, the polymethylpentene membrane 310 is attached to the conveying shaft of the coating machine, and the membrane is pulled out and placed on a clip frame. When the clip frame of the membrane is raised to a predetermined height, the heating box also slides parallel to the clip frame.

[0030] Step 220 is a heating step in which polymethylpentene film 310 is heated to 300° C. to 750° C. and kept at that temperature for 2 to 30 seconds to obtain a softened polymethylpentene film, which has formability and adhesiveness.

[0031] Step 230 is a coating step in which the softened polymethylpentene film is bonded to the fiber base layer 320 via the adhesive layer 313 by a coating method to obtain the coated pulp substrate 300. The low-temperature heat-sealable material in the adhesive layer 313 of the polymethylpentene film 310 is embedded in the gaps between the fibers of the fiber base layer 320, thereby providing excellent bonding properties and firmly bonding the polymethylpentene film 310 to the fiber base layer 320. Meanwhile, the coating method may be a vacuum suction method or a hot air blowing method. In detail, the polymethylpentene film 310 is heated to 300°C to 750°C and kept at that temperature for 2 to 30 seconds to obtain a softened polymethylpentene film, after which the clip frame is dropped vertically onto the workbench, and at this time, the cavity below the workbench begins to work, generating negative pressure to perform suction, and the softened polymethylpentene film sucked by the negative pressure is attached to the fiber base layer 320, or the softened polymethylpentene film is directly attached to the paper plastic container fiber. On the other hand, since polymethylpentene membrane 310 includes matrix layer 312, it is endowed with rigidity and toughness, which allows polymethylpentene membrane 310 to withstand vacuum suction during the coating process. When filled to a predetermined thickness, polymethylpentene membrane 310 is less likely to thin or become completely coated when vacuum suctioned, even if the surface of fiber base layer 320 is not flat. As a result, coated pulp substrate 300 and coated pulp containers manufactured by coated pulp substrate manufacturing method 200 have excellent properties such as heat resistance and high-temperature oil penetration resistance.

[0032] The fiber base layer 320 is made of a fiber material that meets food safety requirements and has excellent elasticity and toughness. The thickness of the fiber base layer 320 can be 50% or more of the overall thickness of the coated molded pulp substrate 300, thereby providing support and shaping for the subsequent food packaging. Fiber materials of different thicknesses and basis weights can also be used depending on the application and needs.

[0033] As a result, the coated molded pulp substrate 300 can be used to manufacture coated molded pulp containers, and the manufactured coated molded pulp containers have good heat resistance and high-temperature oil penetration resistance. Furthermore, when food, especially sticky rice or noodles, is placed inside the container, the food does not stick to the container. Furthermore, because of its excellent heat resistance, the container does not emit harmful substances such as plasticizers or decomposition products, ensuring high safety in terms of food hygiene. Depending on the actual application, the coated molded pulp containers can be made into boxes, bags, cups, plates, bowls, cans, and other shapes, and can be used for sealed food packaging, microwave food packaging, modified atmosphere packaging (MAP), fresh food packaging, general food packaging, and other uses.

[0034] Specifically, Table 1 below shows various formulations for producing polymethylpentene membranes of the present invention, formulations of the proportions of each component of the polymethylpentene membranes of Examples 1 to 3 and the membranes of Comparative Examples 1 to 5, and their melt indexes and adhesive strengths. The melt index was determined in accordance with ASTM D1238, and the adhesive strength was determined in accordance with ASTM D903-98. The material types used in the following experimental examples are polymethylpentene (MX002), polyolefin resin (C7100), metallocene polyolefin (FV402), polypropylene (Y101), polyethylene (CE4043), binder polypropylene (551T), polyamide (NY-B40LN09), ethylene-vinyl acetate copolymer (EVA UE633), ionic copolymer (Surlyn 1652SR), polyethylene terephthalate (DryStar 0603PETG), and polylactic acid (HZ-200).

[0035] [Table 1]

[0036] As can be seen from the comparison results in Table 1, the film produced using only polymethylpentene as a component in Comparative Example 1 does not have adhesive properties, whereas the polymethylpentene films of Examples 1, 2, and 3 of the present invention all have excellent adhesive strength, which can improve the shortcomings of polymethylpentene materials and is advantageous for subsequent processing and coating of fiber base layers onto paper-plastic containers.

[0037] In the experiment, the polymethylpentene film of Example 1 was used to further produce a coated pulp substrate by the method for producing a coated pulp substrate of the present invention, and the coated pulp container of Example 4 was further produced. Additionally, the films of Comparative Examples 2 to 5 were used to further produce coated pulp containers of Comparative Examples 6 to 9 by the same production method, and heat resistance (including hot water resistance and high-temperature oil resistance), whether they could be heated in a microwave or oven, non-stickiness to food, food hygiene and safety, and heat deformation resistance were examined.

[0038] Hot water resistance is tested in accordance with GB / T36787-2018 6.6.1, and high-temperature oil resistance is tested in accordance with GB / T36787-2018 6.6.2. Micro-heating is tested by heating the coated molded pulp container at 1440W for 1 minute, and then observing the oil leakage of the container. If there is no oil leakage, it is rated as excellent. If there is oil leakage, it is further rated as good, fair, or poor depending on the oil leakage. Oven heating is tested by heating the coated molded pulp container to 180°C in an oven and keeping it warm for 5 minutes, and observing the oil leakage or deformation of the coated molded pulp container. If there is no oil leakage or deformation, it is rated as excellent. If there is oil leakage or deformation, it is further rated as good, fair, or poor depending on the oil leakage or deformation. Non-stickiness to food is tested by a blocking test according to the method of the federation company, and the coated molded pulp container is tested. Viscous food is placed in a pulp container and observed to see if the food sticks to the film-coated pulp container. If there is no sticking, it is rated as excellent. If there is sticking, it is further classified as good, fair, or poor depending on the sticking conditions. Food hygiene and safety are tested in accordance with Taiwan's Food Sanitation Standards No. 1111303439. Heat deformation resistance is tested in accordance with the method of Taiwan's Ministry of Health and Welfare's Food Sanitation Standards No. 1061902219. Freeze resistance is tested in accordance with the Alliance Company's method, where a film-coated pulp container is left at -40°C for 24 hours and then dropped from a height of 1.5 meters at -40°C. If the film is not damaged, it is rated as excellent. If the film is damaged, it is further classified as good, fair, or poor depending on the damage conditions. Table 2 below shows the results of the above experiments on the coated pulp container of Example 4 and the coated pulp containers of Comparative Examples 6 to 9, where ◎ indicates excellent, ○ indicates good, Δ indicates fair, and × indicates poor.

[0039] [Table 2]

[0040] With respect to hot water resistance, the coated molded pulp containers of Comparative Examples 7, 8, and Example 4 achieved excellent results. In food hygiene and safety tests, the results of testing the coated molded pulp containers of Comparative Example 7 and Example 4 showed that no plasticizer was released. With respect to freeze resistance, the coated molded pulp containers of Comparative Examples 6, 8, and Example 4 achieved excellent results. However, in tests of high-temperature oil resistance, microwave heating compatibility, oven heating compatibility, non-sticking to food, and heat deformation resistance, only the coated molded pulp container of Example 4 achieved excellent results. As can be seen from the test results in Table 2, the coated molded pulp container of Example 4 exhibits excellent hot water resistance, high-temperature oil resistance, non-stick properties to food, food hygiene and safety, heat deformation resistance, and freeze resistance. Furthermore, since it can be heated in a microwave or oven, coated molded pulp containers made with the coated molded pulp substrate of the present invention can be used to store various foods, such as instant foods, which can be refrigerated or frozen and then heated in a microwave or oven for consumption. The coated molded pulp containers made with the coated molded pulp substrate of the present invention not only exhibit minimal thermal deformation after heating, but also have insulating properties, making them convenient to carry. Furthermore, the coated molded pulp substrate of the present invention exhibits non-stick properties to food, and the coated molded pulp containers produced do not stick or remain sticky even when sticky foods, such as rice or noodles, are placed inside. Furthermore, the coated molded pulp substrate of the present invention is resistant to hot water and high-temperature oil, and the produced coated molded pulp containers are particularly suitable for containing hot soup or foods containing hot oil, eliminating the need for plastic bags and can safely replace coated molded pulp containers made with existing membrane materials. This is an environmentally friendly, safe and hygienic solution that brings great benefits to food safety and human health.

[0041] In experiments, when heated under different heating conditions using an oven, a microwave oven, and a steam oven, the high-temperature oil penetration resistance of the coated pulp container of Example 4 was detected under the test conditions shown in Table 3 below. In the oven heating test and microwave heating test, 200 mL of salad oil was poured into the coated pulp container of Example 4, and after the test time was over, the coated pulp container of Example 4 was checked for oil leakage. In the steam oven heating test, cooked food was placed in the coated pulp container of Example 4, and after the test time was over, the coated pulp container of Example 4 was checked for oil leakage.

[0042] [Table 3]

[0043] As can be seen from the test results in Table 3, when heated in an oven, high-temperature oil did not penetrate the coated pulp container of Example 4 even at an oil temperature of 160°C, when heated in a microwave oven, high-temperature oil did not penetrate the coated pulp container of Example 4 even at a heating power of 1440W, and when heated in a steam oven, high-temperature oil did not penetrate the coated pulp container of Example 4 even at a heating temperature as high as 220°C. This demonstrates that the coated pulp containers made from the coated pulp substrate of the present invention have excellent resistance to high-temperature oil penetration and can therefore be used to store hot food or to heat the food stored therein in a microwave oven, oven, steam oven, etc.

[0044] Although the present invention has been clarified in the above embodiments, it is not intended to limit the present invention, and anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined based on what is defined by the appended claims. [Explanation of symbols]

[0045] 100, 310: Polymethylpentene film 110, 311: Functional surface layer 120, 312: Matrix layer 130, 313: Adhesive layer 200: Method for producing coated pulp substrate 210, 220, 230: Process 300: Coated molded pulp base material 320: fibrous basal layer

Claims

1. a functional surface layer formed of a functional material, the functional material being polymethylpentene or a blend of the polymethylpentene and a polyolefin-based resin, the polyolefin-based resin having a monomer of C2 to C4 olefin molecules, and the content of the polymethylpentene in the blend being 20% by weight to 99% by weight relative to 100% by weight of the total weight of the blend; a matrix layer formed by coextrusion on one surface of the functional surface layer and made of a polymeric material, the polymeric material being a thermoplastic polyolefin, an aromatic polymer, a polyamide polymer, a polyethylene copolymer, or a combination thereof; an adhesive layer formed by co-extrusion on a surface of the matrix layer away from the functional surface layer, the adhesive layer being made of a low-temperature heat-sealable material, the low-temperature heat-sealable material being a metallocene polyolefin, an olefin-based copolymer, the polyolefin-based resin, or a combination thereof; A polymethylpentene membrane comprising:

2. 2. The polymethylpentene membrane of claim 1, wherein the functional material in the functional surface layer has a first melt index, the polymeric material in the matrix layer has a second melt index, and the low-temperature heat-sealable material in the adhesive layer has a third melt index, and the difference between the maximum and minimum values of the first melt index, the second melt index, and the third melt index is less than 20.

3. The polymethylpentene membrane according to claim 1, wherein in the functional surface layer, the polyolefin resin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, or a combination thereof.

4. 2. The polymethylpentene membrane of claim 1, wherein in the matrix layer, the thermoplastic polyolefin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, polymethylpentene, a thermoplastic elastomer, a polyolefin elastomer, or a combination thereof, the aromatic polymer is polystyrene, the polyamide polymer is polyamide, and the polyethylene copolymer is ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-butyl acrylate copolymer, or a combination thereof.

5. The polymethylpentene film of claim 1, wherein in the adhesive layer, the metallocene polyolefin is an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene-α-olefin trimer, or a combination thereof, and the olefin copolymer is an ionic copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-butyl acrylate copolymer, or a combination thereof.

6. The polymethylpentene film according to claim 1, wherein the adhesive layer has an adhesive strength of 20 g or more.

7. The polymethylpentene membrane of claim 1 , further comprising a barrier layer disposed between the functional surface layer and the matrix layer or between the matrix layer and the adhesive layer.

8. 8. The polymethylpentene membrane of claim 7, wherein the material composition of the barrier layer is ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyamide, polyvinyl alcohol, or a combination thereof.

9. Providing a polymethylpentene membrane according to any one of claims 1 to 8; a heating step of heating the polymethylpentene film to 300°C to 750°C and maintaining the temperature for 2 seconds to 30 seconds to obtain a softened polymethylpentene film; a coating step of bonding the softened polymethylpentene film to the fiber base layer via the adhesive layer by a coating method to obtain a coated pulp substrate; A manufacturing method comprising:

10. The method for producing a coated pulp base material according to claim 9, wherein the coating method is a vacuum suction method or a hot air blowing method.

11. 10. A coated pulp substrate produced by the method of claim 9, wherein the thickness of the fibrous base layer is 50% or more of the total thickness of the coated pulp substrate.

Images