JP2001011229A - Heat-resistant foamed sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foamed sheet which can be formed into a shape not undergoing high-temperature deformation even when it is a deep container and improved in heat resistance, oil resistance, and surface properties by mixing a specified polypropylene resin with a cycloolefin resin and a blowing agent in an extruder and extruding the mixture into a low pressure zone. SOLUTION: A mixed resin is obtained by mixing 50-95 pts.wt. polypropylene resin having a melt tension of at least 5 g at 230 deg.C with 50-5 pts.wt. cycloolefin resin. The mixed resin (100 pts.wt.) and 1-10 pts.wt. blowing agent are fed into and melt-kneaded in an extruder, and the melt is extruded into air from a ring-lip-equipped circular die to obtain a circular foam. The foam is stretched and cooled with a cooling cylinder and opened by cutting to obtain a heat- resistant foamed sheet having a density of 0.5-0.05 g/cm3, a closed-cell rate of at least 60%, a thickness of 0.8-10 mm, and a cell count of at least 4. It is desirable that the temperature of the molten resin containing the blowing agent is kept at a temperature ranging from the crystallization temperature of the resin to (the melting temperature of resin) +20 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a heat-resistant foam sheet,
The present invention relates to a method for producing the foamed sheet. More specifically, the present invention relates to heat resistance, rigidity at heat, oil resistance, heat insulation, impact resistance, and shock resistance composed of a resin composition obtained by mixing a polypropylene resin having a certain melt tension or higher and a cyclic olefin resin. The present invention relates to a heat-resistant foam sheet having excellent moldability and a method for producing the foam sheet.

[0002]

2. Description of the Related Art In general, a foamed sheet made of a thermoplastic resin is light in weight, has good heat insulating properties and good buffering properties against external stress, and can easily obtain a molded article by heating and secondary molding such as vacuum molding. Since it can be used, buffer materials, food containers, heat insulating materials,
Widely used in applications such as automotive components. In particular, polystyrene resin foam sheets are generally used in food applications, but are inadequate in oil resistance and thus are not suitable as food containers containing a large amount of edible oil and the like. Therefore, foamed sheets (for example, Japanese Patent Application Laid-Open No. 5-506875) in which foamability and moldability are improved by subjecting a polypropylene resin having excellent oil resistance to treatment such as electron beam crosslinking and the like have been proposed in recent years.
However, foamed sheets made of a polypropylene-based resin have a high temperature (80
(110 ° C. to 110 ° C.). However, in this temperature range, the rigidity is reduced. For example, in a deep shape such as a bowl type (the side surface area is large), there is a defect that the shape is not formed as a food container. . On the other hand, as a foam using a mixed resin of a polypropylene-based resin and a cyclic olefin-based polymer, Japanese Patent Application Laid-Open No. Hei 9-12819 has been disclosed, but when a general-purpose polypropylene is used, a sheet-shaped foam is formed. In this case, there were problems such as poor surface properties and poor moldability when producing a molded article.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molded article having excellent heat resistance, oil resistance, and surface properties, and in particular, which does not deform at high temperatures even in a deep shape used in food applications. And a method for producing the same.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that a mixed resin obtained by mixing a suitable amount of a polypropylene resin having a certain or more melt tension and a cyclic olefin copolymer. It has been found that a foamed sheet obtained by using the above method can provide a molded article having excellent heat resistance, moldability, rigidity at high temperatures, and oil resistance, and completed the present invention. That is, the present invention provides: (a) 50 to 95 parts by weight of a polypropylene resin having a melt tension at 230 ° C. of 5 g or more;
A heat-resistant foamed sheet using a mixed resin of 50 to 5 parts by weight of a cyclic olefin resin as a base resin (Claim 1); (a) 50 to 95 parts by weight of a polypropylene resin having a melt tension of 5 g or more at 230 ° C; b)
The heat-resistant foam sheet (Claim 2) according to claim 1, which is obtained by mixing 50 to 5 parts by weight of a cyclic olefin-based resin with a mixed resin and a foaming agent by an extruder and extruding the mixture into a low pressure zone. The heat-resistant foamed sheet according to claim 1 or 2, wherein the resin is a resin obtained by modifying a linear polypropylene-based resin by reaction with an isoprene monomer and a radical polymerization initiator. 0.5-0.05 g / cm ³ ,
4. The heat-resistant foam sheet according to claim 1, 2 or 3, wherein the closed cell ratio is 60% or more, the thickness is 0.8 to 10.0 mm, and the number of cells in the thickness direction is 4 or more. And 50 to 95 parts by weight of a polypropylene resin having a melt tension of 5 g or more in (b)
A resin composition obtained by kneading 50 to 5 parts by weight of a cyclic olefin resin with a foaming agent at a high temperature and a high pressure is extruded under a low pressure through an annular die and foamed into a cylindrical shape. The present invention relates to a method for producing a heat-resistant foamed sheet, characterized in that the sheet is stretched and cooled in a cooling cylinder provided with an enlarged portion, cut open, taken off in a sheet shape, and a foamed sheet is obtained.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is essential to use a mixed resin of a polypropylene resin and a cyclic olefin resin having a melt tension at 230 ° C. of 5 g or more.

The melt tension at 230 ° C. is 5 g
When a smaller polypropylene-based resin is used, it is difficult to impart foamability even when mixed with a cyclic olefin-based resin. That is, with a mixture of a polypropylene resin and a cyclic olefin resin having a melt tension of less than 5 g at 230 ° C., it is not easy to form a cell membrane because of insufficient resin tension in cell formation at the time of foaming, and the cell is broken ( (Foam breakage), surface properties and the like are easily deteriorated, and a good foam cannot be obtained. On the other hand, a mixture of a polypropylene-based resin and a cyclic olefin-based resin having a melt tension at 230 ° C. of 5 g or more has a sufficient resin tension, so that a foamed sheet having good cell formation and excellent surface properties can be obtained. At the same time, a foamed sheet made of a mixture of a polypropylene-based resin and a cyclic olefin-based resin having a melt tension of 5 g or more at 230 ° C. has a sufficient melt tension at the time of heating even in the secondary molding for molding into a shape such as a food container. Shows good secondary moldability with little drawdown. In addition, since the completed food container contains a cyclic olefin-based resin, the heat resistance is improved, and better heat resistance, particularly heat-resistant stiffness, can be obtained than a foamed sheet of a polypropylene-based resin alone. As the polypropylene resin having a melt tension at 230 ° C. of 5 g or more, a polypropylene having a long-chain branch by electron beam irradiation, a linear propylene containing an ultrahigh molecular weight component,
Modified polypropylene obtained by reacting a polypropylene resin with a radical polymerizable monomer such as isoprene or styrene and a radical initiator is exemplified. Among these, a modified polypropylene that can variously modify the properties of the resin according to the application is preferable.

The polypropylene resin used for the modified polypropylene resin is a homopolymer, a block copolymer or a random copolymer of propylene, and includes a crystalline polymer. As the propylene copolymer, those containing 75% by weight or more, especially 90% by weight or more of propylene are advantageous in that crystallinity, rigidity, chemical resistance, and the like, which are characteristics of the polypropylene resin, are maintained. preferable. As monomers copolymerizable with propylene, ethylene, butene-1, isobutene, pentene-1, 3-methyl-butene-1, hexene-1,
Α-olefins having 2 or 4 to 12 carbon atoms such as 4-methyl-pentene-1, 3,4-dimethyl-butene-1, heptene-1, 3-methyl-hexene-1, octene-1, decene-1 and the like , Cyclopentene, norbornene, 1,
4,5,8-Dimethano-1,2,3,4,4a, 8,8
cyclic olefins such as a-6-octahydronaphthalene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-
Diene such as 1,4-hexadiene, 7-methyl-1,6-octadiene, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, ethyl acrylate, butyl acrylate, methyl methacrylate , Maleic anhydride, styrene,
One or more kinds of vinyl monomers such as methylstyrene, vinyltoluene, and divinylbenzene are exemplified.

The shape and size of the polypropylene resin are not limited, and may be in the form of particles or pellets.

The addition amount of the radical-reactive monomer is as follows:
0.1 to 100 parts by weight of the polypropylene resin
100 parts by weight, especially 0.1 to 50 parts by weight, is preferred in that the modified polypropylene resin retains the impact resistance, chemical resistance and the like characteristic of the polypropylene resin. Examples of the radical reactive monomer are vinyl monomers such as isoprene, styrene, methylstyrene, vinyltoluene, chlorostyrene, chloromethylstyrene, bromostyrene, fluorostyrene, nitrostyrene, vinylphenol, divinylbenzene, and isopropenylstyrene; Vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, metal acrylate, metal methacrylate, methyl acrylate, ethyl acrylate Acrylates such as butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethyl methacrylate Sill, methacrylic acid esters such as stearyl methacrylate, and the like may be used by copolymerizing them. Isoprene and styrene are preferred from the viewpoint of easiness of modification and versatility, and isoprene is particularly preferred. Examples of the radical polymerization initiator generally include a peroxide and an azo compound. In order for a graft reaction to occur between the polypropylene-based resin and the isoprene monomer (a polymer composed of) or the polypropylene-based resin, a material having a so-called hydrogen abstracting ability is required. Generally, ketone peroxide, peroxyketal And organic peroxides such as hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate and peroxyester. Among them, those having high hydrogen extraction ability are particularly preferable. For example, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-
Peroxy ketals such as bis (t-butylperoxy) cyclohexane, n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, dicumyl peroxide , 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α′-bis (t-butylperoxy-m-
Isopropyl) benzene, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3
Dialkyl peroxides such as benzoyl peroxide, t-butyl peroxy octate, t-butyl peroxyisobutyrate, t-butyl peroxy laurate, t-butyl peroxy 3,5,5 -Trimethylhexanoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5di (benzoylperoxy) hexane,
One or more of peroxyesters such as t-butylperoxyacetate, t-butylperoxybenzoate, and di-t-butylperoxyisophthalate are exemplified. The amount of the radical polymerization initiator to be added is 0.1 to 100 parts by weight of the polypropylene resin.
1 to 10 parts by weight, especially 0.5 to 5 parts by weight, is preferred in that the excessive decrease in the melt viscosity of the modified polypropylene resin is suppressed, and that it is economical. Examples of an apparatus for reacting the polypropylene-based resin, the radical-reactive monomer, and the radical polymerization initiator include a kneader such as a roll, a co-kneader, a Banbury mixer, a brabender, a single-screw extruder, and a twin-screw extruder. Examples thereof include a horizontal stirrer such as a shaft surface renewing machine and a two-shaft multi-disc device, and a vertical stirrer such as a double helical ribbon stirrer. Of these, extruders are particularly preferred from the viewpoint of productivity. The order and method of mixing and kneading (stirring) the polypropylene resin, the radical-reactive monomer and the radical polymerization initiator are not particularly limited.
After mixing the polypropylene-based resin, the reactive monomer and the radical polymerization initiator, the mixture may be melt-kneaded (stirred),
After melt-kneading (stirring) the polypropylene-based resin, the reactive monomer and the radical initiator may be mixed simultaneously or separately, collectively or separately. The temperature of the kneading (stirring) machine is preferably 130 to 400 ° C. in that the polypropylene resin is melted and does not thermally decompose. The time is generally 0.5 to 60 minutes.

The cyclic olefin resin (b) used in the present invention is mixed for improving heat resistance. The foamed sheet composed only of the polypropylene-based resin (a) has low rigidity at high temperatures.
(0 ° C to 100 ° C), the rigidity is reduced and the container may be deformed. Since the cyclic olefin-based resin (b) has excellent rigidity when heated, there is an advantage that mixing the cyclic olefin-based resin (b) can prevent deformation of the container at a high temperature. The cyclic olefin-based resin (b) to be used is not particularly limited, but is disclosed in JP-A-2-133413 and JP-A-2-2-2.
No. 8932 and JP-A-6-145408 can be used. Cyclic olefin polymers, ethylene / cyclic olefin random copolymers, cyclic olefin ring-opening (co) polymers, and ring-opening (co) Hydrogenated products of (co) polymers. For example, it is a copolymer of ethylene and the following monomers, and the monomers include 1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene and 2 -Methyl-1,4,5,8-
Dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydro Naphthalene, 2-propyl-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2-hexyl-1,4,5,8-dimethano-1, 2,3,4,4a, 58,8a-octahydronaphthalene, 2-stearyl-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2, 3-dimethyl-1,4,5,8-dimetano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2-methyl-3-ethyl-1,4,5,8
-Dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2-chloro-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octa Hydronaphthalene, 2-bromo-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene, 2-fluoro-1,4,5,8-dimethano-1 , 2,3,4,4a, 58,8a-octahydronaphthalene, 2,3-dichloro-1,4,5,8-dimethano-1,2,3,4,4a, 58,8a-octahydronaphthalene And bicyclo [2.2.1] hept-2-ene derivatives, tricyclo [4.3.0.12,5
] -3-decene derivative, tricyclo [4.3.0.1
2,5] -3-undecene derivative, tetracyclo [4.
4.0.12,5. 17,10] -3-dodecene derivatives, pentacyclo [6.6.1.13,6. 02,7. 09,14] -4
-Hexadecene derivative, pentacyclo [6.5.1.1
3,6. 02,7. 09,13] -4-hexadecene derivative, pentacyclo [7.4.0.12,5. 09, 12.08, 13]-
3-pentadecene derivative, pentacyclopentadecadiene derivative, pentacyclo [8.4.0.12,5. 09,1
2.08,13] -3-pentadecene derivative, hexacyclo [6.6.1.13,6.110,13. 02,7. 09,14] −
4-heptadecene derivative, heptacyclo [8.7.0.
13,6. 110,17. 112,15. 02,7. 011,16] -4
-An eicosene derivative, heptacyclo [8.7.0.13,
6.110,17. 112,17. 02,7. 01,16] -5-eicosene derivative, heptacyclo [8.8.0.14,7.
111,18.113,16. 03,8. 01,17] -5-heneicosene derivative, heptacyclo [8.8.0.12,9.
14,7. 111,18. 03,8. 01,17] -5-heneicosene derivative, octacyclo [8.8.0.12,9. 1
4,7. 111,18. 113, 16.03, 8. 012.17] -5
A dococene derivative, nonacyclo [10.9.1.14,7.
113,20. 115,18. 03,8. 02, 10.012, 21. 11
4,19] -5-pentacocene derivative, nonacyclo [1
0.10.1.15,8. 114,21. 116,19. 02,11.
04,9. 013,22. 115,20] -5-hexacocene derivative, 1,4-methano-1,4,4a, 9a-tetrahydrofluorene derivative, 1,4-methano-1,4,4a,
5,10,10a-hexahydroanthracene derivative,
It is obtained from a cyclic olefin such as a cyclopentadiene-acenaphthylene adduct, among which bicyclo [2.2.1] hept-2-ene derivative and tetracyclo [4.4.0.12,5. [17,10] -3-dodecene derivatives are preferred. Commercially available products include, for example, cyclic olefin copolymers (trade name: Apel) manufactured by Mitsui Petrochemical Industry Co., Ltd., amorphous polyolefins (trade name: ZEONEX) manufactured by Zeon Corporation, and Nippon Synthetic Rubber A functional norbornene resin (trade name: Arton) manufactured by Co., Ltd. is preferably used. The mixing ratio of the cyclic olefin-based polymer to the propylene-based resin is 50 to 95 parts by weight of the cyclic olefin-based polymer relative to 50 to 95 parts by weight of the propylene-based resin, and preferably 60 to 90 parts by weight of the propylene-based resin. It is 40 to 10 parts by weight of the cyclic olefin polymer. When the amount of the propylene-based resin is less than 50 parts by weight and the amount of the cyclic olefin-based polymer is more than 50 parts by weight, the chemical resistance, oil resistance and the like are inferior, and the amount of the propylene-based resin is more than 95 parts by weight and the cyclic olefin-based polymer is If it is less than 5 parts by weight, high temperature (8
(0 ° C. to 110 ° C.). In the present invention, a compatibilizer (C) may be added to further improve the foamability. As the compatibilizer, for example, an olefin-based thermoplastic elastomer such as an amorphous or low-crystalline polyolefin copolymer, such as an ethylene-α-olefin copolymer or a propylene-α-olefin copolymer, is particularly preferably used. used. When these compatibilizers are added, uniform dispersion of the cyclic olefin resin in the propylene resin is promoted, and a foam having a uniform foam cell diameter distribution is easily obtained. Among the commercially available compatibilizers, "Tuffmer" (trade name) manufactured by Mitsui Petrochemical Industries, Ltd., "Engage" (trade name) manufactured by Dow Chemical Company, and "Exact" (trade name) manufactured by Exxon Chemical Company Etc. can be suitably used. The mixing ratio of the compatibilizer is 1.
The amount is preferably about 0 to 40 parts by weight, more preferably 5.0.
-30 parts by weight. If the amount of the compatibilizer is less than 1.0 part by weight, the compatibilizing effect is insufficient and no remarkable improvement in foaming properties is observed. If the amount exceeds 45 parts by weight, the strength and heat resistance of the foam may be reduced. . In the mixed resin, if necessary,
Other resins or rubbers may be added as long as the effects of the present invention are not impaired. Examples of the other resin or rubber include polyethylene; poly-α-olefins such as polybutene-1, polyisobutene, polypentene-1, and polymethylpentene-1; ethylene / propylene copolymers having a propylene content of less than 75% by weight; Ethylene / butene-1 copolymer, ethylene or α-olefin / α-olefin copolymer such as propylene / butene-1 copolymer having a propylene content of less than 75% by weight; propylene content of less than 75% by weight Ethylene / propylene / 5
Ethylene or α-olefin / α-olefin / diene monomer copolymer such as ethylidene-2-norbornene copolymer; ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid Copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / maleic anhydride copolymer,
Ethylene / vinyl monomer copolymers such as ethylene / metal acrylate copolymer, ethylene / metal methacrylate copolymer, ethylene / glycidyl methacrylate copolymer; polydiene copolymers such as polybutadiene and polyisoprene Copolymer; vinyl monomer such as styrene / butadiene / styrene block copolymer / diene monomer / vinyl monomer block copolymer; acrylonitrile / butadiene / styrene graft copolymer, methyl methacrylate /
Vinyl monomer such as butadiene / styrene graft copolymer / diene monomer / vinyl monomer graft copolymer; polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyvinyl acetate, polyethyl acrylate,
Vinyl polymers such as polybutyl acrylate, polymethyl methacrylate, and polystyrene; vinyl chloride / acrylonitrile copolymer, vinyl chloride / vinyl acetate copolymer, acrylonitrile / styrene copolymer, methyl methacrylate / styrene copolymer, etc. And the like. The amount of these other resins or rubbers added to the raw polypropylene resin depends on the type of the resin or the type of the rubber, and may be within the range that does not impair the effects of the present invention as described above. ,Normal,
It is preferably about 25% by weight or less. Further, if necessary, an antioxidant, a metal deactivator, a phosphorus-based processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, a mixed resin or a polypropylene-based resin, a cyclic olefin-based resin in a range that does not impair the effects of the present invention, Stabilizers such as fluorescent whitening agents, metal soaps, antacid adsorbents, crosslinking agents, chain transfer agents, nucleating agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, flame retardants, antistatic agents, etc. Additives may be used. As the stabilizer, pentaerythritol-tetrakis [3- (3,5-di-t)
-Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-
Butyl-5-methyl-4-hydroxyphenyl) propionate], tris (monononylphenyl) phosphite, tris (2,4-di-t
Phosphorus stabilizers such as -butylphenyl) phosphite;
Sulfur-based stabilizers such as dilauryl thiodipropionate,
Representative examples of the lubricant include sodium, calcium and magnesium salts of lauric acid, palmitic acid, oleic acid and stearic acid. The mixing method of the target resin to be used may be any method, for example, a method in which the granular or powder of each component resin is uniformly blended by a blender or the like, a method in which this is once passed through a kneading extruder and then melt-blended. . In the present invention, as the foaming agent, both a chemical foaming agent and a physical foaming agent used in the production of ordinary extruded foams can be used. Is more preferred. First, examples of chemical foaming agents include azodicarbonamide, trihydrazinotriazine, diazoaminobenzene, N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N,
N'-dinitroterephthalimide, barium azodicarboxylate, p, p'-oxybisbenzenesulfonylhydrazine and the like can be mentioned. The physical foaming agent is also called an evaporating foaming agent or a volatile foaming agent,
While the chemical foaming agent is thermally decomposed by heating to generate gas, the foaming agent itself dissolves in the resin in the extruder, and precipitates (exudes) from the resin due to a sudden pressure drop, vaporizes, and undergoes a chemical change. To produce a foam without the presence of Therefore, the physical foaming agent has an effect of apparently lowering the melt viscosity of the resin by dissolving in the resin (plasticizing effect), and when added in a large amount, the processing temperature can be significantly lowered. In addition, since it absorbs heat of vaporization from the surroundings when vaporizing after precipitation from the resin, it promotes cooling of the resin film,
Increases resin film strength and suppresses cell membrane breakage during foaming.
Therefore, when the physical foaming agent is used, the foaming ratio of the obtained foam can be increased while maintaining the independence of the cells as compared with the case where the chemical foaming agent is used. Specific examples of the physical foaming agent include, for example, propane,
aliphatic hydrocarbons such as n-butane, i-butane, n-pentane, i-pentane, neopentane, n-hexane and cyclohexane; methyl chloride, methylene chloride, ethyl chloride, chlorodifluoromethane, 1,1-dichloro-
2,2,2-trifluoroethane, 2-chloro-1,
1,1,2-tetrafluoroethane, 1,1,1-trifluoro-2-chloroethane, 1,1-dichloro-1-
Fluoroethane, 1-chloro-1,1-difluoroethane, trifluoromethane, difluoromethane, 1,1-
Difluoroethane, 1,1,2-trifluoroethane,
1,1,1-trifluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, octafluoropropane, 1,1,1-trifluoropropane, 2, And halogenated hydrocarbons such as 2-difluoropropane. Lower aliphatic hydrocarbons having 3 to 5 carbon atoms are particularly preferably used in view of the solubility in the olefin resin and the vapor pressure necessary to achieve a desired expansion ratio. In addition, carbon dioxide (CO ₂ ), water (H ₂ O), nitrogen (N ₂ ), and the like may be used as a foaming agent or a foaming assistant. These foaming agents or foaming assistants may be used alone or in combination of two or more. The amount of the physical foaming agent to be added is 1 to 10 parts, preferably 2 to 5 parts, per 100 parts of the mixed resin. When the amount of the foaming agent is less than 1 part, the foaming ability is insufficient and a desired expansion ratio cannot be obtained. When the amount exceeds 10 parts, uniform dispersion and dissolution of the foaming agent in the extruder sufficiently proceed. Otherwise, the foam may be uneven. A nucleating agent can be added to the foam of the present invention as needed. Examples of the nucleating agent include talc, TiO ₂ , indigo, kaolin, silica,
Silicate, zeolite 4A, sodium benzoate, citric acid / sodium bicarbonate mixture, hydroxy-di-p-
Aluminum t-butyl benzoate and the like are preferred. Also,
Metal salts of higher fatty acids such as potassium stearate, sodium stearate, calcium stearate, magnesium stearate and zinc stearate; bisbenzylidene sorbitol, bis (p-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol, 2,2 -Methylenebis (4,6-di-t-butylphenyl) sodium phosphite and the like can also be used. Further, the foamed sheet made of the mixed resin in the present invention, for example,
After melt-kneading the mixed resin and the foaming agent in the extruder, adjust the foaming optimal temperature in the extruder, use a circular die having an annular lip, and extrude from the lip of the die into atmospheric pressure to form a cylindrical foam. Then, it is easily manufactured by a method in which the cylindrical foam is stretched, cooled, cut open, and formed into a sheet by molding with a cooling cylinder (mandrel) while taking the cylindrical foam. In addition, extrusion foaming may be performed continuously with the production of the modified polypropylene resin composition.

In obtaining the foamed sheet of the present invention, a foaming agent
The temperature of the molten resin containing
Above, it is preferable to keep the melting temperature of resin + 20 ° C or less
No. Also, the pressure inside the die is 1.5MPa or more.
It is preferable that the pressure be 15 MPa or less. In addition, the present invention
Foam comprising a modified polypropylene resin composition
In order to obtain the desired cell structure, for example, extrusion
Cooling was promoted by blowing air after foaming
Alternatively, it may be stretched at the time of being taken to a mandrel. Departure
The density of the foamed sheet made of the mixed resin in Ming is 0.5
~ 0.05g / cm ^ThreePreferably 0.3 to 0.06 g /
cm^Three0.2 to 0.08 g / cm^ThreeGood to be
Good. 0.05g / cm^ThreeIf less, rigid
May not be enough, 0.5g / cm^ThreeGreater than
In some cases, the heat insulation may not be sufficient. Heat resistance of the present invention
In the foam sheet, the closed cell rate is preferably 60% or more.
More preferably, it is 70% or more, more preferably 80% or more. 60%
In the following cases, the secondary expansion ratio during heat molding is small.
In some cases, the mold rules are not good.

In the present invention, the thickness of the heat-resistant foam sheet is as follows:
It is 0.8 to 10 mm, more preferably 1 to 5 mm. If it is less than 0.8, the heat insulating property, rigidity and cushioning property may not be sufficient, and if it is more than 5 mm, the moldability may not be sufficient. The number of cells is preferably five,
Further, seven or more are preferable. If the number is smaller than 5, the heat insulating property and the surface property may not be sufficient. Further, the heat-resistant foam sheet of the present invention is excellent in heat moldability such as plug molding, vacuum molding, and air pressure molding, so that a molded article with less thickness unevenness and beautiful appearance can be obtained. Examples of heat molding include plug molding, matched mold molding, straight molding, drape molding, plug assist molding, plug assist / triverse draw molding, air slip molding, snapback molding, reverse draw molding, free drawing molding, plug -Methods such as and ridge molding and ridge molding are available. The heat moldability of the heat-resistant foam sheet is, for example, 35 mm
After being placed in an oven set at 0 ° C. and preheated for 25 seconds, the outer diameter of the opening is 130 mm, the outer diameter of the bottom is 80 mm, and the height is 70 m by plug molding using a mold adjusted to 38 ° C.
It can be evaluated by preparing a m-shaped bowl. In other words, a molded article obtained from a foamed sheet having excellent secondary formability has a good appearance, but a foamed sheet having poor secondary formability has drawdown during preheating, and the obtained molded article has many irregularities and streaks on its surface. In some cases, the wall thickness is so severe that it cannot be used. The heat molding is performed after pre-heating the foam sheet. However, the density, thickness, and closed cell rate may change due to secondary foaming of the foam sheet during pre-heating. The heat-resistant foamed sheet of the present invention may have a non-foamed layer made of a thermoplastic resin on one or both sides of the foamed sheet, for the purpose of improving surface properties, rigidity, heat moldability, and the like. . As the thermoplastic resin, polystyrene resin, modified polyphenylene ether resin, polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate, polyamide resin, polyarylate resin, polyimide resin,
Polyethersulfone resins, polysulfone resins, polyester resins, acrylic resins, polyvinyl chloride resins, polycarbonate resins, and the like can be used. These may be used alone or in combination of two or more, and a polypropylene resin is particularly preferable from the viewpoint of adhesiveness to a foam sheet. The method of forming the non-foamed layer is not particularly limited, and may be formed by preparing a foamed sheet and then laminating a separately prepared non-foamed film by heating or using an adhesive, A non-foamed film may be extruded directly from a T-die onto a sheet and formed by lamination.

[0013]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. <Resin property measurement method> 1) Melt tension 1 m diameter using a melt tension tester manufactured by Toyo Seiki Co., Ltd.
m, length 10mm, inflow angle 45 degrees orifice 19
10mm / mi of polypropylene resin heated to 0 ° C
The extruded material is extruded at a speed of n, passed through a pulley for tension detection, wound up while being accelerated from a speed of 1 m / min, and the tension required for taking up the extruded product until it is cut is measured. The tension at the time of this break was defined as the melt tension of the polypropylene resin.

<Evaluation Method of Foam> The density, closed cell ratio and average cell diameter of the obtained plate-like foam were measured by the following methods, and the appearance was visually evaluated according to the following evaluation criteria. 1) Measurement of density of foam sheet Measured according to JIS-K6767. 2) Measurement of closed cell rate of foamed sheet Measured with an air pycnometer according to the method described in ASTM D-2856. 3) Measurement of Thickness of Foam Sheet Measurement points are provided at intervals of 30 mm in the width direction of the foam sheet, and the thickness of each measurement point is measured using a thickness gauge (a thickness gauge manufactured by teclock). Is the thickness of the foam sheet. 4) Measurement of the number of cells in the thickness direction of the foam sheet Ten measurement points are provided at equal intervals in the width direction of the foam sheet,
The number of cells in the thickness direction at the measurement point is determined using a loupe (peaco).
The measurement was carried out using a pocket.micro × 10 manufactured by ck. Thereafter, the average of the measured values at each point was defined as the number of cells in the thickness direction. 5) Appearance The appearance of the foam sheet was visually evaluated according to the following criteria. ：: The surface is clean and there is no problem. ×: There are problems such as corrugation, wrinkles, and surface roughness. 6) Moldability evaluation Visually evaluated according to the following criteria ◎: Molded into a mold without drawdown,
No wrinkles are observed. ：: There is a little drawdown, but it is molded in the shape of a mold, and no wrinkles are observed. Δ: Molded into the shape of a mold, but wrinkles were observed. 7) Evaluation of the rigidity of the foamed body at the time of heating The hot water at 85 ° C. was put to about 80% of the molded body, and the deformation of the shape of the molded body was visually observed and evaluated according to the following criteria. A: No deformation is observed at all. ：: Deformation is slightly recognized, but there is no problem in practical use. Δ: Deformation is slightly observed, but there is no problem in practical use. ×: Deformed and unusable.

(Example 1) 100 parts by weight of a propylene homopolymer (B101W manufactured by Grand Polymer) and a radical polymerization initiator (trade name: Perbutyl I manufactured by NOF Corporation)
Was fed to a twin-screw extruder (TEX44XCT-38) manufactured by Nippon Steel Works Co., Ltd. with a measuring feeder, and from the middle of the extruder using a liquid addition pump. Supplying 2.5 parts by weight of isoprene,
The mixture was melt-kneaded in the twin-screw extruder and melt-extruded to obtain pellets of the modified polypropylene resin composition.

The twin-screw extruder was of the same-direction twin-screw type, had a screw diameter of 44 mmφ, and had a maximum effective screw length (L / D) of 38. The set temperature of the cylinder of this twin-screw extruder should be 1 until the isoprene monomer is injected.
The temperature was set to 80 ° C., 200 ° C. after the injection of isoprene, and the screw rotation speed was set to 150 rpm.

70 parts by weight of the modified polypropylene resin composition (melt tension 11 g), 30 parts by weight of cyclic olefin resin (APL6015 manufactured by Mitsui Chemicals, Inc.), 0.05 parts by weight of blended oil, cell nucleating agent (Eiwa Industries) A mixture prepared by stirring and mixing 0.5 parts by weight of Cerbon SC / K) with a ribbon blender was supplied to a 40-50 mmφ tandem type extruder, and the first-stage extruder (4
0 mmφ), 2.5 parts by weight of isobutane was injected as a blowing agent into 100 parts by weight of the mixed resin, and the mixture was extruded into a second-stage extruder (50 mm
φ), discharge under atmospheric pressure from a circular die (54 mmφ), and form while cooling with a cooling cylinder having an enlarged part diameter (A) of 150 mm, a cooling cylinder body diameter (a) of 147 mm, and a body length of 80 mm. While taking in at a rate of 0.2 m / min, air was blown into the inside at a rate of 0.15 m ³ / min to stretch and cool to obtain a cylindrical foam, which was cut open with a cutter to obtain a 470 mm wide foam sheet.

When the foamed sheet was evaluated, the density was 0.17 g / cm ³ , the closed cell ratio was 90%, the number of cells was 7, and
The thickness was 1.6 mm, and the appearance evaluation was ○. Further, the foamed sheet was clamped, and the foamed sheet was placed in an oven set at 350 ° C. and preheated for 25 seconds.
The outer diameter of the opening is 130 mm and the outer diameter of the bottom is 8 by plug molding using a 1.5 mm clearance (T) mold.
A bowl-shaped molded product having a height of 0 mm and a height of 70 mm was prepared, and the heat moldability was evaluated from the appearance of the obtained molded product according to the following criteria. Table 1 shows the results.

Example 2 A foamed sheet was obtained in the same manner as in Example 1, except that 55 parts by weight of the modified polypropylene resin composition and 45 parts by weight of the cyclic olefin resin (APL6015 manufactured by Mitsui Chemicals, Inc.) were used. And evaluated.
Table 1 shows the results.

Example 3 A foamed sheet was obtained in the same manner as in Example 1 except that 90 parts by weight of the modified polypropylene resin composition and 10 parts by weight of the cyclic olefin resin (APL6015 manufactured by Mitsui Chemicals, Inc.) were used. And evaluated.
Table 1 shows the results. (Example 4) The polypropylene resin used was changed (manufactured by Montell: SD613, melt tension 7.5 g).
Other than the above, a foamed sheet was obtained in the same manner as in Example 1, and molded and evaluated in the same manner. Table 1 shows the results.

Comparative Example 1 A foamed sheet was obtained in the same manner as in Example 1, except that 100 parts by weight of the modified polypropylene resin and 0 part by weight of the cyclic olefin resin were used. It was molded and evaluated in the same manner. Table 1 shows the results
Shown in

(Comparative Example 2) A foamed sheet was obtained in the same manner as in Example 1 except that the polypropylene resin was changed (F109BA, manufactured by Grand Polymer Co., Ltd., melt tension: 0.4 g), and molded and evaluated in the same manner. . Table 1 shows the results.

The comparative example is inferior in actual use because the molded article has poor rigidity when heated, but the example is a molded article excellent in rigidity when heated. Example 3 is slightly inferior in rigidity to heat as compared with Examples 1, 2, and 4. This is because the amount of the cyclic olefin polymer is small. This is because the polypropylene resin has a lower melt retention than that of the examples.

[0024]

According to the heat-resistant foamed sheet of the present invention, it is possible to obtain a good molded product excellent in heat resistance, heat rigidity, oil resistance and moldability.

[0025]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 105: 04 B29L 7:00 F term (Reference) 4F074 AA24 AA28 AA54 AB05 AD08 BA01 BA31 BA38 CA22 CC02Z CC03Y CC05Z CC22X CC32X CC34X DA02 DA12 DA14 DA23 4F207 AA11 AA12 AB02 AG01 AG08 AG20 AH17 AH55 AH56 AH58 AH81 KA01 KA11 KA19 KK13 KK23 KK76 KL88 KW41 4F212 AA11C AA11J AA12 UA12 AA12 UA12A01A02A02A01 BB151 BB201 BB211 BK002 BP021 DE016 DE026 EA016 EB026 EB066 EQ016 ES006 EU026 EU186 EV286 FD030 FD326

Claims (5)

[Claims] 1. A heat-resistant foam comprising a base resin comprising a mixed resin of (a) 50 to 95 parts by weight of a polypropylene resin having a melt tension of 5 g or more at 230 ° C. and (b) 50 to 5 parts by weight of a cyclic olefin resin. Sheet. 2. An extruder comprising: (a) 50 to 95 parts by weight of a polypropylene resin having a melt tension of 5 g or more at 230 ° C .; and (b) 50 to 5 parts by weight of a cyclic olefin resin, and a mixed resin and a foaming agent. The heat-resistant foamed sheet according to claim 1, wherein the heat-resistant foamed sheet is obtained by mixing and extruding into a low pressure zone. 3. The resin according to claim 1, wherein the polypropylene resin is a resin obtained by modifying a linear polypropylene resin by reaction with an isoprene monomer and a radical polymerization initiator.
The heat-resistant foam sheet according to the above. 4. The heat-resistant foam sheet has a density of 0.5 to 0.05 g.
/ Cm ³ , closed cell rate of 60% or more, thickness 0.8 to 10.
The number of cells in the thickness direction is 0 mm and the number of cells in the thickness direction is 4 or more.
Or the heat-resistant foamed sheet according to 3. 5. Kneading (a) 50 to 95 parts by weight of a polypropylene resin having a melt tension of 5 g or more at 230 ° C. and (b) 50 to 5 parts by weight of a cyclic olefin resin with a foaming agent under high temperature and high pressure. The obtained resin composition is extruded under a low pressure through an annular die and foamed in a tubular shape, and the tubular foam is stretched and cooled in a cooling cylinder provided with an enlarged portion on the die side, and then cut open to form a sheet. A method for producing a heat-resistant foamed sheet, comprising obtaining a foamed sheet.