JPS637942B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to packaging materials, and an object of the present invention is to prevent packaged articles from being altered or deteriorated due to harmful gases mixed in a packaging container. In the packaging of foodstuffs and precision electrical and mechanical parts, hermetic packaging materials that can be isolated from the outside air are used to prevent oxidation, deterioration, corrosion, staining, etc. due to contact with the outside air. However, it is often difficult to achieve complete sealing from the outside air, and it is impossible to avoid oxidation, corrosion, and deterioration of the packaged articles due to gases existing in the gaps between the articles in the packaging container. The most important cause of such problems is that reactive gases such as oxygen are mixed in and remain inside the packaging container. As a result, in food packaging, food materials undergo corrosion due to oxidation, deterioration, and microbial growth occurs in food containers containing oxygen, and in packaging for electrical contact materials and mechanical parts, rust occurs due to oxidation of the materials. do. Gas replacement packaging and vacuum packaging have been conventionally used as methods for preventing oxygen remaining in packaging containers from causing deterioration of packaged articles. However, in gas replacement packaging, in which the air in the packaging container is replaced with a gas that does not contain oxygen, such as nitrogen, carbon dioxide, or a mixture of these gases,
It is unavoidable that outside air containing at least 2% by volume, usually about 4% by volume of oxygen, will re-enter the packaging container around the nozzle of the replacement device during the sealing process, and for this reason, it is difficult to prevent the product from being stored for long periods of time. The reality is that the progress of oxidation, deterioration, and corrosion cannot be prevented. On the other hand, vacuum packaging, in which the packaging container is evacuated after the packaged product is stored in the packaging container, may not be usable because the packaged product itself contains substances that are easily extracted by vacuum, such as moisture, as in food packaging. Water or water-soluble substances are extracted from the inside of the product and segregated on the surface of the food, which has the disadvantage of impairing taste and flavor. Furthermore, not only is the vacuum packaging process itself large-scale and expensive, but there are also problems in that there are very few packaging materials that can be kept under vacuum for a long period of time. In addition, there are oxygen scavengers that use hydrosulfite to remove oxygen through a chemical reaction, but they have the disadvantage of generating harmful gases such as sulfur dioxide and hydrogen sulfide during the chemical reaction process, and are expensive. . There are also oxygen scavengers that use enzymes such as glucose oxidase, but enzymatic reactions are extremely difficult to control temperature, hydrogen ion concentration, and humidity, making actual use complicated and expensive. The present inventors have solved all of these problems by developing a simple and simple method that can quickly remove harmful gases remaining inside packaging containers and quickly remove harmful gases that enter from the outside during long-term storage. We investigated inexpensive and reliable packaging methods, first focusing on converting the harmful gas inside the packaging container into other harmless substances, and further, in order to prevent the generated substances from adversely affecting the quality of the packaged goods. We discovered that covering with a thin layer of gas selective permeability was effective.
This led to the present invention. That is, the present invention provides a packaging material comprising a substrate, a thin layer of a catalytic material deposited in vacuum on the substrate, and a thin layer of a gas selectively permeable material laminated on the thin layer of the catalytic material, the packaging material comprising: A packaging material is provided in which the catalytic material is comprised of palladium and the gas selectively permeable material is comprised of at least one organic polymer selected from the following group: low-density polyethylene, high-density polyethylene, propylene, ethylene-propylene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polybutene-1, ionomer, poly4-methyl-1-pentene or polybutadiene. The detailed contents of the present invention will be explained below. It is used as a packaging material for goods because of its good gas barrier properties, good transparency and beauty, ease of various printing, easy sealing, and excellent flexibility. Mainly organic polymer films are often used. The catalyst-coated substrate used in the present invention is characterized in that all of these commonly used packaging materials can be used. That is, examples of catalyst-adhered substrates used in the present invention include polyethylene, polypropylene, polybutene-1, ethylene propylene copolymer, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polystyrene, and polyether. , polyvinyl alcohol, polyester represented by polyethylene terephthalate, “Surlyn”
Stretched or unstretched films of raw materials made of organic polymers such as ionomers (manufactured by Dupont), polycarbonates, polyamides, polyimides, polyamideimides, cellulose, acetate, etc. alone or in mixtures, or the above polymers and silicones, Molded articles made of organic polymers such as polyurethane, polysulfone, phenol, melamine, urea resin, and epoxy resin are preferred. Various known additives, such as heat stabilizers, antioxidants, lubricants, antistatic agents, colorants, clarifying agents, ultraviolet inhibitors, or pigments, are added to these organic polymer base materials. Good too. Furthermore, there are films in which the above film materials are laminated into two or more layers by extrusion lamination, dry lamination, etc., films in which these films and metal foils such as aluminum foil are bonded and laminated, or aluminum is formed by vacuum evaporation, etc. , those coated with metals such as zinc, tin, etc., and those coated with printing can also be used in exactly the same way. Other materials such as thin metal plates, glass, and paper can also be used, but it is unavoidable that the catalyst is difficult to adhere to and the amount of adhesion is relatively large compared to organic polymer films. The shape of these catalyst-coated substrates is not particularly limited due to the nature of the present invention;
The label, lining sheet, inner lid, etc. must be in a shape that can be practically stored inside the packaging container. In addition, when the catalyst-coated substrate ultimately constitutes the outer wall of the packaging container, the oxygen permeability of the substrate itself is 10 c.c. 24hr・^m2・100μ・
A pressure of 1 atm or less is most preferred. Palladium is used as the catalytic material deposited on such a substrate. In general, a known method for depositing a catalyst substance on a substrate is to immerse the substrate in a solution of a metal compound that will serve as a catalyst so that the substrate is adsorbed on the surface, and then reduce it by firing in a high-temperature furnace such as a hydrogen stream. It has been found that it is difficult to develop catalytic activity when the substrate is flat or non-water absorbent, such as an organic polymer film. We also attempted a method in which palladium-coated alumina particles with a particle diameter of 1 to 500 microns were coated on the surface of a substrate using an organic polymer as a binder and dried, but the activity remained low even when a large amount of catalyst material was filled. It became clear that it could not be used because it was too small. The most preferable method for achieving the object of the present invention is to convert the palladium into an atomic or molecular gas in a vacuum and then deposit it on a substrate. Examples of such a vacuum deposition method include a vacuum evaporation method, an ion plating method, and a sputtering method. In either case, the process involves the step of converting the material into atomic or molecular gases and then redepositing the material onto the substrate. Through this process, the catalyst substances deposited on the substrate reduce their kinetic energy by colliding and cooling on the substrate, and coalesce with each other to form fine island-like structures or network structures with diameters of several 10 Å to several 100 Å. It can be applied to the substrate. Among them, when the sputtering method is adopted as a vacuum deposition method, it is possible to create an island-like structure with uniform particle size and small diameter by sufficiently adjusting the sputtering conditions, and when depositing such a structure, the catalyst activity It was found that the highest value can be obtained. The amount of catalyst material deposited on the substrate is 10 ^-7 mol/m ²
It is preferable that ^{the catalytic activity is in the range of 5×10 -3 mol / m 2 from} degree decreases significantly. Among them, the amount of adhesion is from 10 ^-6 mol/m ² to 5×
A range of 10 ⁻⁴ mol/m ² is most preferable because the catalyst activity is high relative to the amount of adhesion. When depositing the catalyst material by the sputtering method, various methods such as direct current sputtering, high frequency sputtering, and magnetron sputtering can be employed. The discharge gas to be filled is preferably an inert gas such as argon, neon, or xenon, or a non-oxidizing gas such as nitrogen or hydrogen, and the inclusion of a large amount of oxygen, water vapor, etc. is not preferable because it reduces the catalytic activity. A layer of gas selectively permeable material is formed on the thin layer of catalyst material deposited in this manner. The gas selectively permeable material has good permeability to two or more reactive gases present in the packaging container,
It is necessary that the reactive gas has a low permeability to the substance produced by the catalytic reaction. When removing oxygen from a packaging container for the purpose of preventing corrosion, quality deterioration, rust, etc. due to oxidation of a packaged article, hydrogen that reacts with oxygen is simultaneously added to the container. As a result, oxygen and hydrogen permeate through the gas selectively permeable material layer and produce water vapor or water on the catalyst layer. The generated water moistens the packaged articles and, in the case of food packaging, changes the hardness, taste, and texture, or causes the foods to coagulate, stick, etc. to each other. In order to prevent these problems, the layer made of a gas selectively permeable material is selected to have a low water vapor permeability. Preferred gas-selective permeable materials having good permeability to oxygen gas and hydrogen gas and low permeability to water vapor include, for example, low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer. , ethylene-ethyl acrylate copolymer, polybutene-1, ionomer, poly4-methyl-1-pentene, polybutadiene, polystyrene, polycarbonate, polyisobutylene, and other organic polymers alone or in mixtures; Although some are laminated, they are not necessarily limited to these. The most preferable gas selectively permeable materials are those whose volumetric hydrogen permeability and volumetric oxygen permeability are 10 times or more the weight water vapor permeability, such as low-density polyethylene, high-density polyethylene, and eletine-propylene copolymers. , ionomers, mixtures based on these, or copolymers with these. These organic polymer raw materials contain various known additives, such as heat stabilizers, lubricants,
Plasticizers, colorants, clarifying agents, ultraviolet inhibitors, etc. may be added. The thickness of the coating layer of the gas-selective permeable substance is preferably 5 to 5, considering the permeability and barrier properties of each gas.
100μ, most preferably 10 to 50μ. All commonly used methods can be used to form the layer of the gas selectively permeable material on the thin layer of the catalyst material. That is, it can be formed by, for example, a solution coating method, extrusion lamination, dry lamination, adhesion with a gas selectively permeable film using an adhesive, vacuum evaporation, discharge polymerization, or the like. Prior to these coating layers, the surface of the catalyst-coated substrate may be appropriately subjected to surface treatments such as anchor coating, discharge treatment, and EC treatment for the purpose of increasing adhesion. When the substrate to which the catalyst material and the gas-selective saccharifying thin layer are applied by such a method constitutes a packaging container, a heat-sensitive, pressure-sensitive, or heat-sensitive pressure-sensitive adhesive layer may be coated or laminated as necessary. Thereafter, it is formed into a container such as a bag with the gas selectively permeable thin layer placed inside. Moreover, it may be stored as it is together with the packaged article in a normal packaging container. After a packaged article such as food or precision parts is stored in such a packaging container, a gas that reacts with the harmful gas inside the packaging container or the harmful gas generated from the packaged article is sealed in the packaging container, or the reaction is After the process of enclosing the gas-emitting substance within the packaging container, the container must be hermetically sealed. For example, hydrogen is used as an enclosed gas to remove oxygen from a packaging container in order to prevent corrosion, quality deterioration, rust, etc. due to oxidation. In this case, an amount of hydrogen equivalent to twice the volume of residual oxygen or more is enclosed, but it is also possible to use a mixture of hydrogen and other gases such as nitrogen and carbon dioxide. In the packaging of ordinary articles, it is preferable from the viewpoint of safety and workability to use a nitrogen mixed gas containing 8% by volume or less of hydrogen rather than using hydrogen alone, which is a flammable gas. Furthermore, if a substance that generates hydrogen slowly at room temperature and pressure is used, there is no need to take the trouble to add hydrogen gas, which is more preferable in terms of workability and safety. Substances that generate hydrogen include the following metal hydrides, such as lanthanum-nickel, magnesium-nickel, zirconium-iron, zirconium-cobalt, zirconium-chromium,
There are hydrides of magnesium-copper, zirconium, and magnesium, and among them, those that easily release hydrogen at room temperature and pressure are desirable. By using the packaging material according to the invention,
Harmful oxygen gas easily reaches the catalyst coating layer along with hydrogen gas through the gas selectively permeable thin layer, and due to the catalytic action, even at room temperature, it easily reacts with hydrogen and turns into a trace amount of water. And the water produced is
Since it is blocked by the gas selectively permeable thin layer and is prevented from coming into direct contact with the product, it has become possible to maintain the packaged product in a state with no deterioration in quality even when stored for a long period of time. Although examples of oxygen and hydrogen have been shown above, the present invention is not limited to these. As described above, the packaging material of the present invention has unique effects, but it also has a greater effect of blocking heat rays from direct sunlight and ultraviolet rays than ordinary packaging materials, and has a high permeability of air outside the packaging into the inside of the bag. It also has the characteristic of being small. Packaging materials based on the present invention include oil confectionery such as potato chips, castella, rice crackers, peanuts, kamaboko, chikuwa, shaved bonito flakes, cheese, powdered milk, ham sausage, instant noodles, bread, fish, meat, raw vegetables,
Foods such as fruits, canned foods such as fish and meat, beverages such as green tea, black tea, coffee, cocoa, sake, wine, whiskey, tobacco, various medicines such as vitamins, electrical contact materials, precision tools, precision measuring instruments It can be used for all kinds of packaging. Next, embodiments of the present invention will be described in detail. Example 1 Palladium was deposited on a biaxially stretched polyethylene terephthalate film ("Lumirror" manufactured by Toray Industries, Inc., thickness: 12 μm) by a sputtering method. For sputtering, DC bipolar sputtering was used. A palladium plate with a width of 400 mm, a length of 200 mm, and a thickness of 1 mm is loaded onto a water-cooled target holder.
Using this as a cathode, we were able to apply a voltage of -3kV. A 400 mm wide polyethylene terephthalate film was run along a metal water-cooled drum placed opposite the cathode. First, the inside of the vacuum system is evacuated to 5×10 ^-5 Torr, and then 99.99% pure dry argon gas is filled in to maintain the pressure at 7×10 ^-2 Torr, and a voltage is applied to the cathode to generate a plasma discharge. occurred. Palladium was deposited at various thicknesses on the substrate film while changing the film running speed and applied voltage. When the applied voltage is 3kV and the film speed is 10m/min
A uniform catalyst adhesion layer of 2.5×10 ^-4 mol/m ² was formed. Furthermore, high-density polyethylene was laminated to a thickness of 20 microns on the film by extrusion lamination. The high-density polyethylene used was Mitsui Petrochemical Co., Ltd.'s "Hisex" 5000F. The amount of palladium deposited on the substrate film was actually measured by activation analysis. On the other hand, as a film with high gas barrier properties, a composition made of polyvinylidene chloride is coated on one side of a polypropylene film, and polyethylene is further laminated on the coated side (total thickness of 50μ), so that the polyethylene side is on the inside. In this way, a bag with an internal volume of 500 c.c. was produced. Here, the composition made of polyvinylidene chloride was applied under the following conditions. Coating agent “Krehalon” DOA TX-27 (vinylidene chloride copolymer manufactured by Kureha Chemical Co., Ltd.) 100 parts by weight of solids “Zeon” 121 1.25 parts by weight (vinyl chloride straight polymer manufactured by Nippon Zeon Co., Ltd.) Zinc stearate 0.25 parts by weight Mixed emulsion (concentration: 30% by weight) Coating amount: 1 g/m ² (solid content) Drying: 140°C for 4 seconds In addition, for polyethylene, low-density polyethylene “Sumikasen-L705” (manufactured by Sumitomo Chemical Co., Ltd.) is extruded at 340°C. Rougeon laminated (approximately 35μ thick). Inside this bag is ^100cm2 of palladium coated film.
Oxygen concentration meter manufactured by Toshiba Beckman (Model 777)
and the detection part of SHAW's multi-range dew point meter, and the hydrogen concentration is 8% by volume and the nitrogen concentration is 8% by volume.
After replacing the air inside with 92% by volume replacement gas, the opening was heat sealed. Table 1 shows the continuous measurements of the oxygen concentration and dew point inside the bag after it was sealed. The oxygen concentration immediately after sealing was 3 to 4% in all cases. In all cases in which the palladium-coated film was encapsulated, the oxygen concentration decreased to 0.4% or less after the passage of time. Comparative Example 1 Palladium was sputtered onto a substrate film in the same manner as in Example 1, but using a catalyzed film without high-density polyethylene lamination. , the oxygen removal effect and dew point were measured. Table 2 shows the results.
Shown below. Although the oxygen concentration was able to be reduced, the dew point inside the bag rose and the bag wall surface became dew-condensed. Example 2 A palladium film was attached to the film used in Example 1 on a substrate by vacuum evaporation. A palladium plate with a purity of 99.9% is heated and vaporized by electron beam heating, and then released from a heating crucible under a pressure of 5 × 10 ^-5 Torr.
It was attached to a film substrate placed at a distance of 25 cm.
The amount of palladium deposited was measured by activation analysis.
Thereafter, the oxygen concentration and dew point inside the bag were measured in the same manner as in Example 1. As a result of examining the temporal change in oxygen concentration and dew point using a deposited film having the same deposition amount as the sample created by sputtering in Example 1, it was found that oxygen removal effect and dew condensation prevention were achieved. In this case, internal oxygen could be removed in a shorter time. Example 3 5 x 10 ^-5 mol/m ² of palladium was deposited on one side of a 35μ thick biaxially stretched polypropylene film by the sputtering method in the same manner as in Example 1, and 20μ of low density polyethylene (Sumitomo Chemical Co., Ltd.) was deposited on the attached surface. "Sumikasen-L705" manufactured by Co., Ltd.) was extruded and laminated. On the other side, apply an ethyl acetate solution of an adhesive whose main component is acrylic ester-methacrylic ester copolymer (copolymerization ratio = 99.5:0.5% by weight), and dry with hot air at 100°C. , the solvent was removed by evaporation. The film thus produced was cut out to a size of 30 mm x 30 mm (this will be referred to as A film). On the other hand, heat sealable polypropylene film (Toray Industries, Inc.)
As in Example 1, a composition made of polyvinylidene chloride was applied to the non-heat-sealed surface of a film (manufactured by TM214, 40μ thick) (this is referred to as B film). Next, the A film was attached to a part of the heat sealing surface of the B film other than the heat sealing part by pressure bonding so that the adhesive surface of the A film was aligned with the heat sealing surface. Using the film thus produced, a packaging bag with an internal volume of 500 c.c. was made with the heat-sealed surface facing inside, heat-sealed, and the oxygen concentration and dew point inside the bag were was measured. As a result, the oxygen concentration of 3.4% by volume immediately after sealing was 24
After hours, it becomes 0% by volume, and the dew point is -20 immediately after sealing.
℃ temperature dropped to -18℃, but there was no condensation. Example 4 An ethyl acetate solution of the adhesive mainly composed of the acrylic ester/methacrylic ester copolymer used in Example 7 was applied to the corona discharge treated surface of a biaxially oriented polypropylene film ("Torefane" BO T2530 20μ). After coating, the solvent was evaporated to dryness under hot air at 100°C for 1 minute, and 50μ aluminum foil was attached to the adhesive side. Palladium was deposited on the aluminum surface at a rate of 5×10 ^-4 mol/m ² by sputtering, and then ethylene-propylene copolymer "FA-6411" from Sumitomo Chemical Co., Ltd. was applied to the palladium-deposited surface.
5μ laminated. A bag having an internal volume of 500 c.c. was made so that the ethylene-propylene copolymer side of the composite laminated film thus obtained was on the inside, heat-sealed, and the oxygen concentration was measured in the same manner as in Example 1. As a result, the oxygen concentration was 3.6% by volume immediately after sealing, but after two days, it became 0% by volume, and no dew condensation occurred inside the container. Example 5 Aluminum with a thickness of 800 Å was vacuum deposited on a biaxially stretched polyethylene terephthalate film ("Lumirror" manufactured by Toray Industries, Inc., thickness 25 microns), and palladium was sputtered on the deposited surface in the same manner as in Example 1. . The amount of palladium attached is 2×
It was adjusted to be 10 ^-4 mol/m ² . Furthermore, a film was prepared by laminating the same low density polyethylene as in Example 3 with a thickness of 25 microns on the palladium layer. A cylindrical bag with a diameter of 60 mm was created using the film, and green tea, coffee, and cocoa were each stored inside, and the bag was replaced with a gas mixture having a nitrogen concentration of 92% by volume and a hydrogen concentration of 8% by volume. Three types of samples were created by thermocompression bonding the openings. Even after being stored at a constant temperature of 30℃ for 6 months, the aroma and flavor did not change and the product remained as fresh as before packaging. Example 6 In the same manner as in Example 1, 10 ^-4 mol/m ² of palladium was deposited on the substrate by sputtering, and then an ionomer resin (Surlyn manufactured by Dupont) was deposited on the film by extrusion lamination. ”) was laminated to a thickness of 15μ. The extrusion temperature was 230°C. Using 100 cm ² of this laminated film, the oxygen removal effect and dew point were measured in the same manner as in Example 1. Table 3 shows the results of measuring the oxygen concentration and dew point inside the bag after it was sealed. After two days, the oxygen concentration remained below 0.1% and the dew point remained below 0°C. Example 7 Using the same sputtering method as in Example 1, a film was prepared in which 10 ⁻⁵ mol/m ² of palladium was deposited on a substrate. Next, polybutadiene resin (manufactured by Japan Synthetic Rubber Co., Ltd.,
JSR RB820) was melt extruded at 200°C and cooled on a metal roll at 20°C to produce a 50μ thick sheet. This sheet was laminated on the palladium surface of the film and heat-sealed with an iron heated to 80°C to obtain a laminated film. Using 100 cm ² of this laminated film, the oxygen removal effect and dew point were measured in the same manner as in Example 1. Table 3 shows the measurement results of the oxygen concentration and dew point inside the bag after sealing. Example 8 Using pellets of ethylene-vinyl acetate copolymer (“ELVAX” 420 manufactured by Mitsui Polychemical Co., Ltd.), melt extrusion was carried out in the same manner as in Example 7,
A sheet with a thickness of 30μ was produced. Extrusion temperature is 220
℃. This sheet was laminated with the same palladium-coated film used in Example 7, and pressed between two iron plates heated to 120°C at a pressure of 2 kg/cm ² to obtain a laminated film. . Using 100 cm ² of this laminated film, the oxygen removal effect and dew point were measured in the same manner as in Example 1. Table 3 shows the measurement results of the oxygen concentration and dew point inside the bag after sealing. Example 9 A sheet with a thickness of 35 μm was obtained in the same manner as in Example 7 except that polybutene resin (M1600 manufactured by Mitsui Petrochemicals Co., Ltd.) was used and the extrusion temperature was 180°C. This was adhered to a palladium-coated film in the same manner as in Example 7 at an adhesion temperature of 90°C to obtain a laminated film. Using 100 cm ² of this laminated film, the oxygen removal effect and dew point were measured in the same manner as in Example 1. The measurement results are shown in Table 3. Example 10 In the same manner as in Example 7, ethylene-ethyl acrylate copolymer (A-
702) was extruded at an extrusion temperature of 200°C to obtain a sheet with a thickness of 40μ. On the other hand, a film was obtained in which 10 ⁻⁴ mol/m ² of palladium was attached by sputtering on a biaxially stretched polyethylene terephthalate film having a thickness of 25 μm using the same method as in Example 1. Next, 1 g of an ethyl acetate solution of a urethane adhesive (a mixture of 5 parts of "Takerak" A-385 and 1 part of "Takenate" A-10 manufactured by Takeda Pharmaceutical Co., Ltd.) in ethyl acetate was applied to the film as adhesive solid content. /m ² and dried. This adhesive surface and the sheet of the ethylene-ethyl acrylate copolymer were overlapped and heated to 50°C.
A laminated film was obtained by pressing the book's nip rolls together at a linear pressure of 2 kg/cm. This laminated film is 3
After storing at 40℃ for 1 day, cut into ^100cm2 pieces.
The oxygen removal effect and dew point were measured in the same manner as in Example 1. The results are shown in Table 3. Example 11 The same method as in Example 10 was used except that poly 4-methyl 1-pentene resin (RT-18 manufactured by Mitsui Petrochemical Co., Ltd.) was used and the extrusion temperature was 280°C.
I got a sheet of Next, using the palladium-attached film and urethane adhesive used in Example 10, Example 10 was prepared.
It was adhered to the above thin layer sheet in the same manner as in No. 10 to obtain a laminated film. Using 100 cm ² of this laminated film, the oxygen removal effect and dew point were measured in the same manner as in Example 1.
The measurement results are shown in Table 3.

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Claims (1)

[Scope of Claims] 1. A packaging material comprising a substrate, a thin layer of a catalytic material deposited in vacuum on the substrate, and a thin layer of a gas selectively permeable material laminated on the thin layer of the catalytic material. In the packaging material, the catalytic material is made of palladium, and the gas selectively permeable material is made of at least one organic polymer selected from the following group. Low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polybutene-1, ionomer, poly4-methyl-1-pentene or polybutadiene.