Coated pulp substrate and method for manufacturing 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 a film, a film-forming pulp substrate, and a method for manufacturing the same, and particularly to a polymethylpentene film, a film-forming pulp substrate, and a method for manufacturing the same.

Background Art

[0002] In the current society where industry and commerce are developed, fast food and takeout are widely loved by people in their busy lives. In order to provide food and drinks to customers quickly, conveniently, and cleanly, it is common for stores to put food and drinks in disposable tableware. With the increasing emphasis on the concept of environmental protection in various countries, promoting the reduction of carbon emissions, circular economy, biomass renewable energy, biodegradable recycling materials, and reducing the use of plastic products globally has become a goal that many countries are jointly working towards. As a result, in most stores, film-forming pulp containers (such as cardboard boxes, paper cups, paper bowls, paper plates, etc.) are used to contain food and drinks. Therefore, film-forming pulp containers are gradually replacing plastic containers.

[0003] Film-forming pulp containers combine the environmental protection of paper materials and the waterproof and oil-resistant packaging characteristics of plastic materials. A plastic material is affixed to the surface of a paper-plastic container in a film form to form a film-forming pulp container. The weight of the plastic material accounts for about 10% of the total weight of the container, substantially achieving the goal of reducing plastic in packaging materials, and can also replace part of the packaging use of plastic containers. The material of the film is related to the characteristics of the subsequent film-forming pulp container. Common film materials include polyethylene, polypropylene, polylactic acid, polyethylene terephthalate, etc.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The membranes of commercially available coated pulp containers are mainly made from a mixture of polyethylene and polypropylene, and paper cups and boxes made from coated pulp substrates formed by coating a paper layer with this mixture have a minimum heat resistance temperature of approximately 70°C. Polylactic acid is biodegradable, but its durability and heat resistance are insufficient. On the other hand, polyethylene terephthalate has properties such as acid resistance, alkali resistance, oil resistance, water resistance, and gas barrier properties, but its heat resistance temperature is only about 60°C to 85°C. Coated pulp containers made using the above membrane materials are waterproof, oil resistant, and heat resistant, but when storing hot foods with high temperatures, such as freshly boiled soup or hot porridge, the heat resistance temperature is often exceeded, raising concerns about the release of plasticizers and the precipitation of decomposition products into the food. If hot food packaged in this way is consumed for a long period of time, harmful substances are more likely to accumulate in the body, causing serious adverse effects on health. Therefore, it is important to improve the shortcomings of conventional technology. [Means for solving the problem]

[0005] The object of the present invention is to provide a polymethylpentene film, a coated pulp substrate, and a method for manufacturing the same, which have good heat resistance and high-temperature oil penetration resistance, as well as high safety in terms of food hygiene. A coated pulp container that can be heated in a microwave oven or oven is manufactured using an environmentally friendly material or recycled material that can replace plastics or reduced-waste plastics. The manufactured coated pulp container has excellent heat resistance, high-temperature oil penetration resistance, non-stick properties to food, scratch resistance, food hygiene and safety, heat deformation resistance, and freeze resistance, improving the high-temperature oil penetration resistance of conventional coated pulp containers and meeting the functions required for food packaging. Furthermore, the coated pulp container can be used for the storage, preservation, and heating of food or liquids, and it can also solve the problem of burning hands at high temperatures with plastic packaging containers, and can replace current plastic containers for instant foods, making it useful as a plastic reduction strategy for disposable plastic containers. In addition, the material of the manufactured coated pulp container can be burned in an incinerator, and thermal energy can be recovered without impairing the function of the incinerator.

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

[0007] According to the aforementioned polymethylpentene film, the functional material in the functional surface layer has a first melt index, the polymer 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, second, and third melt indices is less than 20.

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

[0009] According to the aforementioned polymethylpentene film, in the matrix layer, the thermoplastic polyolefin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, polymethylpentene, thermoplastic elastomer, 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 aforementioned 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 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.

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

[0012] The aforementioned polymethylpentene film 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 film-molded pulp substrate, comprising the steps of: providing the polymethylpentene film described in the previous paragraph; heating the polymethylpentene film to 300°C to 750°C and holding the temperature for 2 to 30 seconds to obtain a softened polymethylpentene film; and coating the softened polymethylpentene film by coating it onto an adhesive layer and then onto a fibrous base layer to obtain a film-molded pulp substrate.

[0015] According to the aforementioned method for manufacturing a coated pulp substrate, the coating method is either a vacuum suction method or a hot air blowing method.

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

[0017] To make the above and other objectives, features, advantages, and embodiments of the present invention clearer and easier to understand, the drawings are described below. [Figure 1] This is a schematic diagram showing a polymethylpentene film according to one embodiment of the present invention. [Figure 2] This flowchart shows the steps for a method of producing a coated pulp substrate according to another embodiment of the present invention. [Figure 3] This is a schematic diagram showing a coated pulp substrate according to a further embodiment of the present invention. [Modes for carrying out the invention]

[0018] Several embodiments of the present invention will be described below with reference to the drawings. For clarity, many practical details will be described collectively 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, in order to simplify the drawings, some conventional structures and components are briefly schematic in the drawings, and overlapping components may be represented by the same number.

[0019] Referring to Figure 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 co-extrusion 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 is polymethylpentene (TPX) or a blend of polymethylpentene and a polyolefin resin, wherein the monomer of the polyolefin resin is a C2-C4 olefin molecule, and the polymethylpentene content in the blend is 20% to 99% by weight relative to 100% by weight of the total weight of the blend. The polyolefin resin may be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polybutylene (PB), polybutadiene (PB), or a combination thereof, and the functional material has a first melt flow index, which may be between 0.5 and 50, and preferably between 1 and 30. Polymethylpentene has a melting point of approximately 220°C to 240°C, and its heat resistance is far higher than that of common film materials such as polyethylene, polypropylene, polylactic acid (PLA), and polyethylene terephthalate (PET). It also has low surface tension, repels oily substances, and is non-viscous. Since the functional surface layer 110 contains a sufficient amount of polymethylpentene, the functional surface layer 110 is the most resistant layer to high-temperature oil in the polymethylpentene film 100, 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 surface of the functional surface layer 110 by co-extrusion. The matrix layer 120 is formed of a polymerization material, which is 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, thermoplastic elastomer (TPE), 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 is adhesive 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 the matrix layer 120 as a multilayer polymethylpentene film 100. 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, it 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] Due to its low surface tension, polymethylpentene is difficult to mix with other materials and is difficult to process. Therefore, it is known that most of the films made of polymethylpentene are single-layer structures. The functional material of the functional surface layer 110 of the polymethylpentene film 100 of the present invention is a blend composed of polymethylpentene or a blend of polymethylpentene and a polyolefin resin. By combining a matrix layer 120 that has adhesiveness to the functional surface layer 110, it can be manufactured as a multilayer structure later.

[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 material that can be heat-sealed at low temperature. The material that can be heat-sealed at low temperature is a metallocene polyolefin, an olefin copolymer, a polyolefin resin, or a combination thereof. Further, 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, and the third melt index may be between 0.5 and 50, preferably, the third melt index may be between 1 and 30. The adhesive layer 130 has low-temperature adhesiveness to paper and the adhesive strength is 20 g or more. Therefore, the polymethylpentene film 100 may be adhered to a fiber base layer (not shown) through the adhesive layer 130. The thickness of the adhesive layer 130 may be between 5 μm and 90 μm.

[0025] Furthermore, the difference between the maximum value and the minimum value among the first melt index of the functional material in the functional surface layer 110, the second melt index of the polymer 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. As a result, the materials of the functional surface layer 110, the matrix layer 120, and the adhesive layer 130 have similar fluidity. When manufacturing the polymethylpentene film 100 by coextrusion, since the flow rates between the layers are close, the manufactured polymethylpentene film 100 has excellent quality and appearance.

[0026] Furthermore, the polymethylpentene film 100 may further include a barrier layer (not shown). The barrier layer is provided 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 alcohol copolymer (EVOH: ethylene vinyl silane), polyvinylidene chloride (PVDC: polyvinyl dichloride), polyamide (PA: polyamide), polyvinyl alcohol (PVA: polyvinyl alcohol), or a combination thereof. By providing the barrier layer, the permeation of gases, particularly oxygen gas, carbon dioxide, and nitrogen gas, can be effectively blocked. The ethylene content in the ethylene vinyl alcohol copolymer is 27 to 45 mol%. However, regarding the material composition of the barrier layer, the above is merely exemplary and not limited to these materials. Other materials with high gas barrier properties may also be used.

[0027] Furthermore, the number of layers of the matrix layer 120 may be one or more. By combining the polymer materials in the matrix layer 120, polymethylpentene films 100 with various functions may be designed. This film may have a multilayer structure of 4 layers, 5 layers, or 6 layers or more. However, the present invention is not limited thereto, and the number of layers of the polymethylpentene film 100 may be increased or changed according to the needs of use.

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

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

[0030] Step 220 is a heating step in which the polymethylpentene film 310 is heated to 300°C to 750°C and held at that temperature for 2 to 30 seconds to obtain a softened polymethylpentene film. The softened polymethylpentene film has moldability and adhesive properties.

[0031] Step 230 is a coating step in which a softened polymethylpentene film is bonded to the fiber base layer 320 via an adhesive layer 313 by a coating method to obtain a coated pulp substrate 300. The low-temperature heat-sealable material in the adhesive layer 313 of the polymethylpentene film 310 is fitted into the gaps between the fibers of the fiber base layer 320, thereby providing excellent bonding action and firmly bonding the polymethylpentene film 310 and the fiber base layer 320. On the other hand, 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 held for 2 to 30 seconds to obtain a softened polymethylpentene film. Then the clip frame is dropped vertically onto the workbench. At this time, the cavity below the workbench generates negative pressure and suction as the work begins. The softened polymethylpentene film, sucked in by the negative pressure, is either attached onto the fiber base layer 320 or directly attached onto the paper-plastic container fibers. On the other hand, since the polymethylpentene film 310 includes a matrix layer 312, it provides rigidity and toughness to the polymethylpentene film 310. As a result, the polymethylpentene film 310 can withstand vacuum suction during the coating process, and once filled to a predetermined thickness, it is less likely to become thin or completely coated when vacuum suction is applied, even if the surface of the fibrous base layer 320 is not flat. As a result, the coated pulp substrate 300 and coated pulp container manufactured by the coating-molded pulp substrate manufacturing method 200 have excellent properties such as heat resistance and resistance to high-temperature oil penetration.

[0032] The fibrous base layer 320 is manufactured from a fibrous material that meets food safety requirements and possesses excellent elasticity and toughness. On the other hand, the thickness of the fibrous base layer 320 may be 50% or more of the total thickness of the coated pulp base material 300, thereby providing support and shaping during subsequent food packaging. Furthermore, fibrous materials with different thicknesses and basis weights can be used depending on the application method and needs.

[0033] As a result, the coated pulp base material 300 can be used in the manufacture of coated pulp containers. The manufactured coated pulp containers have good heat resistance and high-temperature oil penetration resistance. Furthermore, when food, especially viscous foods such as rice and noodles, is placed inside, it does not stick to the food and has excellent heat resistance, so there is no release of harmful substances such as plasticizers or decomposition products, resulting in high food hygiene safety. Depending on the actual application, coated pulp containers can be made into box-shaped, bag-shaped, cup-shaped, plate-shaped, bowl-shaped, can-shaped, etc., and can be used for sealed food packaging, microwave food packaging, modified atmosphere packaging (MAP), fresh food packaging, general food packaging, etc.

[0034] Specifically, Table 1 below shows various formulations for producing the polymethylpentene film of the present invention, the formulations of the proportions of each component in the polymethylpentene films of Examples 1 to 3 and Comparative Examples 1 to 5, and their melt index and adhesive strength. The melt index was detected according to ASTM D1238, and the adhesive strength was detected according to ASTM D903-98. The model numbers of the materials used in the following experimental examples are polymethylpentene (MX002), polyolefin resin (C7100), metallocene polyolefin (FV402), polypropylene (Y101), polyethylene (CE4043), adhesive 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 an ingredient in Comparative Example 1 lacked adhesive properties, while the polymethylpentene films of Examples 1, 2, and 3 of the present invention all possessed excellent adhesive strength, improving upon the shortcomings of the polymethylpentene material and proving advantageous for subsequent processing and coating paper-plastic containers with fibrous base layers.

[0037] In the experiment, the polymethylpentene film of Example 1 is used to further produce a coated pulp substrate using the method for producing a coated pulp substrate of the present invention, and the coated pulp container of Example 4 is further produced. Furthermore, the coated pulp containers of Comparative Examples 6 to 9 are further produced using the same manufacturing method with each of the films of Comparative Examples 2 to 5, and their heat resistance (including resistance to hot water and high-temperature oil), whether they can be heated by microwave or oven, non-stick properties to food, food hygiene and safety, and resistance to heat deformation are detected.

[0038] Hot water resistance is detected according to GB / T36787-2018 6.6.1, and high-temperature oil resistance is detected according to GB / T36787-2018 6.6.2. Micro-heating capability is determined by heating the coated pulp container at 1440W for 1 minute, then observing the oil leakage status of the coated pulp container. If there is no oil leakage, it is indicated as excellent; if there is oil leakage, it is further subdivided into good, acceptable, and poor depending on the extent of the leakage. Oven heating capability is determined by heating the coated pulp container in an oven to 180°C and keeping it warm for 5 minutes, then observing whether there is oil leakage or deformation of the coated pulp container. If there is no oil leakage or deformation, it is indicated as excellent; if there is oil leakage or deformation, it is further subdivided into good, acceptable, and poor depending on the extent of the leakage or deformation. Non-stick properties to food are determined by performing a blocking test according to the methods of the federation company. Viscous food is placed in the pulp container, and it is observed whether or not the food sticks to the coated pulp container. If it does not stick, it is indicated as excellent; if it does stick, it is further subdivided into good, acceptable, and poor depending on the degree of sticking. Food hygiene and safety are detected in accordance with Taiwan Food Hygiene and Food Safety Standard No. 1111303439. Heat deformation resistance is detected according to the method of Taiwan Ministry of Health and Welfare Food Hygiene and Food Safety Standard No. 1061902219. Freeze resistance is detected by leaving the coated pulp container at -40°C for 24 hours according to the method of the affiliated company, and then performing a drop test from a height of 1.5 meters at -40°C. If there is no damage to the film, it is indicated as excellent; if there is damage to the film, it is further subdivided into good, acceptable, and poor depending on the degree of damage. Furthermore, Table 2 below shows the results of the above experiment conducted on the coated pulp container of Example 4 and the coated pulp containers of Comparative Examples 6 to 9. Here, ◎ indicates excellent, ○ indicates good, Δ indicates acceptable, and × indicates poor.

[0039] [Table 2]

[0040] Regarding hot water resistance, the coated pulp containers of Comparative Example 7, Comparative Example 8, and Example 4 showed excellent results. In food hygiene and safety tests, the coated pulp containers of Comparative Example 7 and Example 4 were found not to have released any plasticizers. Regarding freeze resistance, the coated pulp containers of Comparative Example 6, Comparative Example 8, and Example 4 showed excellent results. However, in tests for high-temperature oil resistance, microwave heating capability, oven heating capability, non-stick properties to food, and heat deformation resistance, only the coated pulp container of Example 4 showed excellent results. As can be seen from the test results in Table 2, the coated pulp container of Example 4 is excellent in all aspects: resistance to hot water, resistance to high-temperature oil, non-stick properties to food, food hygiene and safety, resistance to heat deformation, and resistance to freezing. Furthermore, it can be heated in a microwave oven or oven. Therefore, coated pulp containers manufactured with the coated pulp substrate of the present invention can be used to store various foods such as instant foods, and the food can be refrigerated or frozen before being heated in a microwave oven or oven and eaten. The coated pulp containers manufactured with the coated pulp substrate of the present invention not only exhibit little thermal deformation after heating, but also have an insulating effect and are convenient to carry. Moreover, the coated pulp substrate of the present invention is non-stick to food, and the manufactured coated pulp containers will not stick or leave residue even when filled with sticky foods such as rice or noodles. Furthermore, the film-molded pulp substrate of the present invention has resistance to hot water and high-temperature oil, and the manufactured film-molded pulp containers are particularly suitable for storing hot soups and foods containing hot oil. There is no need to use plastic bags, and it can safely replace film-molded pulp containers made from existing membrane materials. It is an environmentally friendly, safe, and hygienic solution that brings significant advantages to food safety and human health.

[0041] In the experiment, the high-temperature oil penetration resistance of the coated pulp container of Example 4 was detected under different heating conditions using an oven, microwave oven, and steam oven, as 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 completed, the 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 completed, the 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, even at an oil temperature of 160°C, the high-temperature oil did not penetrate the coated pulp container of Example 4. When heated in a microwave oven, even at a heating power of 1440W, the high-temperature oil did not penetrate the coated pulp container of Example 4. When heated in a steam oven, even at a high heating temperature of 220°C, there was no penetration of the high-temperature oil into the coated pulp container of Example 4. From this, it is shown that the coated pulp container manufactured with the coated pulp base material of the present invention has excellent resistance to high-temperature oil penetration, and therefore can be used to store hot food or to heat food stored inside using a microwave oven, oven, steam oven, etc.

[0044] Although the present invention has been made clear in the embodiments described above, this is not intended to limit the invention, and anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be based on 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 manufacturing coated pulp substrate 210, 220, 230: Process 300: Coated pulp substrate 320: Fiber basement

Claims

1. A coated pulp substrate comprising a polymethylpentene film and a fibrous base layer, The aforementioned polymethylpentene film is A functional surface formed of a functional material, wherein the functional material is polymethylpentene or a blend of the polymethylpentene and a polyolefin resin, the monomer of the polyolefin resin is a C2-C4 olefin molecule, and the content of the polymethylpentene in the blend is 20% to 99% by weight relative to 100% by weight of the total weight of the blend. A matrix layer formed by co-extrusion on one surface of the functional surface layer, wherein the polymer material is a thermoplastic polyolefin, an aromatic polymer, a polyamide polymer, a polyethylene copolymer, or a combination thereof, is formed of the matrix layer. An adhesive layer formed by co-extrusion on the surface of the matrix layer away from the functional surface layer, and made of a material that can be heat-sealed at low temperatures, wherein the material that can be heat-sealed at low temperatures is a metallocene polyolefin, an olefin copolymer, the polyolefin resin, or a combination thereof, and the adhesive strength of the adhesive layer is 20 g / 15 mm or more. Includes, The fibrous base layer is bonded to the polymethylpentene film via the adhesive layer. Coated pulp substrate.

2. The coated pulp substrate according to claim 1, characterized in that the functional material in the functional surface layer has a first melt index, the polymer material in the matrix layer has a second melt index, 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 coated pulp substrate according to claim 1, characterized in that the polyolefin resin in the functional surface layer is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, or a combination thereof.

4. The coated pulp substrate according to claim 1, characterized in that in the matrix layer, the thermoplastic polyolefin is polyvinyl chloride, polyethylene, polypropylene, polybutylene, polybutadiene, polymethylpentene, thermoplastic elastomer, 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 coated pulp substrate according to claim 1, characterized in that, 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 coated pulp substrate according to claim 1, wherein the thickness of the fibrous base layer is 50% or more of the total thickness of the coated pulp substrate.

7. The coated pulp substrate according to claim 1, further comprising a barrier layer provided between the functional surface layer and the matrix layer or between the matrix layer and the adhesive layer.

8. The coated pulp substrate according to claim 7, characterized in that the material composition of the barrier layer is an ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyamide, polyvinyl alcohol, or a combination thereof.

9. A method for producing a coated pulp substrate according to claim 1, A step of providing a polymethylpentene film, wherein the polymethylpentene film is A functional surface formed of a functional material, wherein the functional material is polymethylpentene or a blend of the polymethylpentene and a polyolefin resin, the monomer of the polyolefin resin is a C2-C4 olefin molecule, and the content of the polymethylpentene in the blend is 20% to 99% by weight relative to 100% by weight of the total weight of the blend. A matrix layer formed by co-extrusion on one surface of the functional surface layer, wherein the polymer material is a thermoplastic polyolefin, an aromatic polymer, a polyamide polymer, a polyethylene copolymer, or a combination thereof, is formed of the matrix layer. An adhesive layer formed by co-extrusion on a surface of the matrix layer away from the functional surface layer, and made of a low-temperature heat-sealable material, wherein the low-temperature heat-sealable material is a metallocene polyolefin, an olefin copolymer, the polyolefin resin, or a combination thereof, and the adhesive strength of the adhesive layer is 20 g / 15 mm or more. A step of providing a polymethylpentene film, A heating step is to heat the polymethylpentene film to 300°C to 750°C and hold the temperature for 2 to 30 seconds to obtain a softened polymethylpentene film. A coating step is performed to bond the softened polymethylpentene film to the fibrous base layer via the adhesive layer by a coating method to obtain a coated pulp substrate, A manufacturing method that includes this.

10. The method for producing a coated pulp substrate according to claim 9, characterized in that the coating method is a vacuum suction method or a hot air blowing method.

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