JP5674265B2 - Polyethylene resin composition for foamable laminate, laminate using the same, foamed paper, heat insulating container, and method for producing the same - Google Patents

Description

  The present invention relates to a polyethylene resin composition for a foamable laminate, a laminate thereof, a foamed paper using the same, a heat-insulating container and a method for producing the same, and more specifically, has good moldability during lamination, A polyethylene resin composition for a foamable laminate, in which a sufficiently high foam cell (foamed layer) is obtained by heating, a foamable laminate using the resin composition, a foamed paper obtained from the foamable laminate, and The present invention relates to a heat insulating container such as a cup foamed using the foamable laminate and a method for producing the same.

  Conventionally, as a container having heat insulation properties, a synthetic resin foam is often used. In addition, as a container that is easy to dispose and has good printability, a heat-insulated paper container that uses multiple sheets of paper, or a material in which both sides of a paper substrate are laminated with a polyethylene resin layer, foam the surface of the polyethylene resin layer to provide heat There is a paper container that has been imparted with sex.

As a technology based on paper, there is a technology in which polyethylene is extruded and laminated on at least one surface of the paper, a vapor pressure holding layer is formed on the other surface, and heated to produce a processed paper having an irregular concavo-convex pattern on the surface. Yes (see, for example, Patent Document 1).
In addition, a technique has been proposed in which a thermoplastic resin film is laminated or coated on one side wall surface of a body member, and a foamed heat insulation layer is formed by foaming the film by heating (see, for example, Patent Document 2). Further, in a paper container composed of a container body member and a bottom member, a part of the outer wall surface of the container body member is printed with an organic solvent-containing ink, and the entire outer surface of the body member is covered with a thermoplastic synthetic resin film. A technique has been proposed in which a relatively thick foam layer is present in a printed portion by heating a paper container (see, for example, Patent Document 3). Furthermore, a foamed paper made of a laminate comprising an ethylene-α-olefin copolymer foamed layer polymerized using a single-site catalyst at least from the outer surface side, a paper-based base material layer, and a thermoplastic resin layer, A laminated body has been proposed (see, for example, Patent Document 4 and Patent Document 5). The processed paper and foam laminate that have the foam layer thus obtained are heat-insulated by using a plurality of paper sheets, with excellent compatibility with the hand and excellent heat insulation when foamed into a container. There is a merit that the cost is lower than that of the container.
Moreover, in patent document 6, the time until a thermoplastic resin in a molten state comes into contact with the paper base material from the T-die on at least one surface of the paper base material of the body member raw material sheet in the paper container is 0.11 to 0.33. A raw material sheet for a body member of a paper container formed by extrusion lamination so as to be seconds is shown, and a composition in which two kinds of low density polyethylene are mixed to adjust MFR is described.
However, the conventional laminate having a foam layer and processed paper using the same have not been sufficiently foamable, and further improvement in foamability has been desired. Further, when the MFR is increased in order to improve the foamability, there are problems that the appearance of the foamed layer becomes poor and the workability at the time of extrusion laminating becomes unstable.

Japanese Patent Publication No. 48-32283 JP-A-57-110439 Japanese Patent Laid-Open No. 07-232774 Japanese Patent Laid-Open No. 10-128928 JP 2007-168178 A JP 2008-105747 A

  In view of the above problems, an object of the present invention is to provide a polyethylene resin composition for a foamable laminate, in which a foamed cell (foamed layer) having a sufficiently high height can be obtained by heating and molding processability at the time of laminating. Another object of the present invention is to provide a heat insulating container such as a foamed laminate, a foamed paper having a foamed layer, and a cup using the foamable laminate, and a method for producing the same.

  As a result of intensive studies to solve the above problems, the present inventor has a high pressure having a specific MFR and density and a specific memory effect (ME) value on one surface of a paper-based substrate. A polyethylene resin composition (C) containing a specific amount of two types of high-pressure radical method low-density polyethylene resin (B), a radical-method low-density polyethylene resin (A) and a high-pressure radical method low-density polyethylene resin (B) having a specific density and MFR. A thermoplastic resin (D) having a specific melting point for holding vapor etc. released from the base material, preferably on the other surface of the base material. The laminate formed with the thermoplastic resin layer (II) using the foam is excellent in foamability, and when the polyethylene resin layer (I) is heated, the foamed paper has a good appearance of the foam layer. It found that heat-insulating container of the cup or the like having excellent performance by heating by molding a laminate into a cup shape is obtained, and have completed the present invention.

That is, according to the first invention of the present invention, there is provided a polyethylene resin composition for a foamable laminate, which forms a polyethylene resin layer (I) for foaming on at least one surface of a substrate mainly composed of paper. And
10% to 90% by weight of the high-pressure radical process low-density polyethylene resin (A) satisfying the following characteristics (a1) to (a3), and the following characteristics (b1) to (b2) other than the resin (A) obtained by mixing the 10 to 90% by weight high-pressure radical process low-density polyethylene resin (B), and a polyethylene resin composition (C) satisfies the following properties (c1) ~ (c3) a mixture Moreover, the MFR (a) of the high-pressure radical method low-density polyethylene resin (A) and the MFR (b) of the high-pressure radical method low-density polyethylene resin (B) satisfy the following formula (1): A polyethylene resin composition for foamable laminates is provided.
(A1) MFR (a) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(A2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(A3) The memory effect (ME) measured using the melt indexer used in JIS K7210 under the conditions of a cylinder temperature of 240 ° C. and a constant speed extrusion rate of 3 g / min is 1.7 or more,
(B1) MFR (b) measured in accordance with JIS K7210 is 2 to 70 g / 10 min.
(B2) The test temperature is 23 ° C., and the density measured according to JIS K7112 is 0.905 to 0.940 g / cm ³ .
(C1) MFR (c) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(C2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(C3) Memory effect (ME) measured under the same conditions as (a3) is 1.5 or more
MFR (b) / MFR (a)> 1 ----- Formula (1)

On the other hand, according to the second aspect of the present invention, the first aspect of the present invention, the polyethylene resin composition MFR of (C) (c) a memory effect (ME) is, satisfies equation (2) below A polyethylene resin composition for a foamable laminate is provided.
−0.467 × Ln (MFR (c)) + 2.75 ≦ ME −−−−− Formula (2)
(Where Ln is the natural logarithm)

On the other hand, according to a third invention of the present invention, according to the first or second invention of the present invention, the polyethylene resin composition for foamable laminate is used, and at least one of the base materials mainly composed of paper is used. There is provided a foamable laminate obtained by forming a foamable polyethylene resin layer (I) on the surface.

According to the fourth invention of the present invention, in the third invention of the present invention, the other surface of the substrate is made of a thermoplastic resin (D), and vapor or the like released from the substrate. A foamable laminate is provided in which a thermoplastic resin layer (II) to be retained is further formed.

According to the fifth aspect of the present invention, in the fourth aspect of the present invention, the polyethylene resin layer (I) has a thickness of 20 to 100 μm, and the thermoplastic resin layer (II) has a thickness of 10 to 10 μm. There is provided a foamable laminate having a thickness of 100 μm.

Furthermore, according to the sixth aspect of the present invention, in any one of the third to fifth aspects of the present invention, the difference in melting point between the polyethylene resin composition (C) and the thermoplastic resin (D) is as follows: An expandable laminate is provided that satisfies the formula (3).
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): melting point Tm (° C.) of thermoplastic resin (D) of layer (II) is there)

On the other hand, according to a seventh invention of the present invention, according to any one of the third to sixth inventions of the present invention, the foamable laminate is heated to obtain a polyethylene resin layer (I). Foamed paper is provided.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, the height of the foamed cell formed by foaming the polyethylene resin layer (I) is 370 μm or more. Foamed paper is provided.

According to a ninth invention of the present invention, according to any one of the third to sixth inventions of the present invention, after forming a container using the foamable laminate, the container is heated to obtain a polyethylene resin. An insulated container obtained by foaming layer (I) is provided.

Furthermore, according to the tenth aspect of the present invention, there is provided an insulated container that is a cup-shaped container in the ninth aspect of the present invention.

On the other hand, according to the eleventh aspect of the present invention, the polyethylene resin composition (C) of the first or second aspect of the present invention is used on at least one surface of a base material mainly composed of paper. A thermoplastic resin layer (II) which forms a polyethylene resin layer (I) having a thickness of 20 to 100 μm and holds the vapor etc. released from the base material on the other surface of the base material using the thermoplastic resin (D). After forming the foamable laminate into a container, it is heated at 100 to 200 ° C., and the polyethylene resin layer (I) is formed by at least steam released from the substrate. A method for producing a heat-insulating container characterized by foaming is provided.

According to the twelfth aspect of the present invention, in the eleventh aspect of the present invention, the difference in melting point between the polyethylene resin composition (C) and the thermoplastic resin (D) satisfies the following formula (3): There is provided a method of manufacturing a heat insulating container.
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): Melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): Melting point Tm (° C.) of thermoplastic resin (D) of layer (II) is there)

In the present invention, a polyethylene resin layer (I) made of a specific polyethylene resin composition is formed on at least one surface of a paper-based substrate, and preferably released from the substrate on the other surface of the substrate. Is a polyethylene resin composition for a foamable laminate used in a laminate provided with a thermoplastic resin layer (II) that retains the generated vapor, etc., and has a specific MFR (a) and a memory effect (ME) Two types of high-pressure radical method low-density polyethylene resin compositions, 10 to 90% by weight of radical method low-density polyethylene resin (A) and 10% to 90% by weight of high-pressure radical method low-density polyethylene resin (B) having a specific MFR (b) Polyethylene resin composition having a specific MFR (c) and ME composed of a product, particularly satisfying MFR (b) / MFR (a)> 1 of formula (1) That is, by using a composition comprising a low MFR and high ME high-pressure radical method low-density polyethylene resin (A) and a high MFR high-pressure radical method low-density polyethylene resin (B), the molding processability during extrusion laminating is improved. It is possible to provide a foamable laminate having a foamed layer that is good, has a low loss, has a high foaming ratio, and has a uniform foamed cell at high speed and high productivity.
Further, the present invention is a foam-processed paper foamed using the foamable laminate, and the foaming ratio is increased by heating the polyethylene resin layer (I) of the foamable laminate having excellent foamability. A foamed paper having a foam layer with a uniform foam cell formed and a good appearance is provided, and since it has excellent heat insulation, cushioning, sound insulation and good appearance, sleeve material, anti-slip material, paper plate Used as a tray.
Furthermore, the present invention provides a heat-insulated container molded using the foamable laminate, and by using the resin composition, a foaming ratio is high and uniform foam cells are formed. Since the foamed layer is excellent in heat insulation and appearance, a product such as a heat insulating container such as a cup can be easily obtained.
Also in the above-described heat insulating container manufacturing method, by using the above specific resin composition, the moldability at the time of extrusion laminating is good, the loss is low, the foaming ratio is high, and uniform foaming. It becomes a foam layer in which cells are formed, and can enjoy the above-mentioned merit that it has excellent heat insulation and good appearance, has good workability, and can continuously produce a heat insulating container such as a cup.

Hereinafter, the polyethylene resin composition for a foamable laminate of the present invention, the foamable laminate using the same, foamed paper, a heat insulating container, and a method for producing the same will be described in detail.
In the present specification, foaming refers to the property of foaming by heating. Good foaming refers to a state in which a high foaming ratio can be obtained mainly, and the height of the foamed cell when the foamed cell grows in the thickness direction of the laminate due to vapor from the paper substrate or the like. It becomes a scale. Also, the uniformity of foam cell height (good appearance) is taken into account.

1. Polyethylene resin composition for foamable laminate The polyethylene resin composition for foamable laminate of the present invention is a foam that forms a polyethylene resin layer (I) for foaming on at least one surface of a base material mainly composed of paper. A high-pressure radical method low-density polyethylene resin (A) satisfying the following characteristics (a1) to (a3): 10 to 90% by weight, and other than the resin (A) A polyethylene resin composition (C) obtained by mixing 10% to 90% by weight of a high-pressure radical method low-density polyethylene resin (B) satisfying the characteristics of (b1) to (b2) is as follows. MFR (a) of the high pressure radical method low density polyethylene resin (A) and MFR (b) of the high pressure radical method low density polyethylene resin (B) satisfying the characteristics of (c1) to (c3 ) Satisfies the following formula (1) .
(A1) MFR (a) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(A2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(A3) The memory effect (ME) measured using the melt indexer used in JIS K7210 under the conditions of a cylinder temperature of 240 ° C. and a constant speed extrusion rate of 3 g / min is 1.7 or more,
(B1) MFR (b) measured in accordance with JIS K7210 is 2 to 70 g / 10 min.
(B2) The test temperature is 23 ° C., and the density measured according to JIS K7112 is 0.905 to 0.940 g / cm ³ .
(C1) MFR (c) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(C2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(C3) Memory effect (ME) measured under the same conditions as (a3) is 1.5 or more
MFR (b) / MFR (a)> 1 ----- Formula (1)

  The polyethylene resin composition for a foamable laminate of the present invention contains 90 to 10% by weight of the high pressure radical method low density polyethylene (B) with respect to 10% to 90% by weight of the high pressure radical method low density polyethylene (A) described later. It is a blend. Hereinafter, each component will be described in detail.

(1-1) High pressure radical method low density polyethylene resin (A)
The high pressure radical method low density polyethylene resin (A) is (a1) MFR (a) measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 30 g / 10 min, (a2) Test temperature 23 ° C., density according to JIS-K7112 is 0.905 to 0.940 g / cm ³ , (a3) The melt indexer used in JIS K7210 is used, and the measurement conditions are cylinder temperature 240 ° C., constant speed extrusion rate This is a high-pressure radical method low-density polyethylene resin having a memory effect (ME) measured at 3 g / min of 1.7 or more.

(A1) MFR
The melt flow rate (MFR) of the high-pressure radical method low-density polyethylene resin (A) is 0.1 to 30 g / 10 min, preferably MFR (a) measured according to JIS K7210 (190 ° C., 21.18 N load). Is 0.3 to 28 g / 10 min, more preferably 0.5 to 25 g / 10 min. If the MFR (a) is less than 0.1 g / 10 min, there is a concern that the high-speed workability during extrusion laminating deteriorates. Moreover, what exceeds 30 g / 10min is unpreferable since there exists a possibility that the process stability at the time of an extrusion lamination process may deteriorate.

(A2) Density The density of the high-pressure radical method low-density polyethylene resin (A) is measured at a test temperature of 23 ° C. according to JIS-K7112, and is 0.905 to 0.940 g / cm ³ , preferably 0.907. It is -0.937 g / cm < ³ >, More preferably, it is the range of 0.910-0.935 g / cm < ³ >. If the density is less than 0.905 g / cm ³ , the laminate molding resin does not slide well, and handling becomes worse. Moreover, what a density exceeds 0.940 g / cm < ³ > becomes a thing which is difficult to manufacture industrially.

(A3) Memory effect (ME)
The memory effect of the high-pressure radical method low-density polyethylene resin (A) was measured using a melt indexer used in JIS K7210 and measuring conditions of a cylinder temperature of 240 ° C. and a constant speed extrusion rate of 3 g / min. 1.7 or more, preferably 1.8 or more, more preferably 1.9 or more, and most preferably 2.0 or more. If the memory effect is less than 1.7, the preparation range for preparing the polyethylene composition (C) is limited as described later, and excessive neck-in is caused during processing such as extrusion lamination. In addition, the improvement of the expansion ratio cannot be expected, and a uniform foam cell cannot be obtained.

[Measurement of memory effect (ME)]
Here, for the memory effect (ME), a melt indexer (semi-automatic melt tension meter manufactured by Misuzu Erie Co., Ltd.) used in JIS K7210 was used. The measurement conditions were a cylinder temperature of 240 ° C., a constant speed extrusion rate of 3 g / min. The measurement is performed under the following conditions. That is, a 2.095 mmφ MFR measurement nozzle is set in the apparatus, and the furnace is filled with resin. Place the piston, hold at 0.09 g / min constant speed extrusion for 5 minutes, then perform 3 g / min constant speed extrusion and release air until 6 minutes 30 seconds. After 6 minutes and 30 seconds, the strand was cut while maintaining 3 g / min. The diameter of the strand when the strand length from the lower end of the orifice became 20 mm was measured at 15 mm from the lower end of the orifice. Measure using a measuring instrument (LS-3033). The measured strand diameter is D and the die orifice diameter is D ₀ (2.095 mm), and ME is obtained by the following formula (however, the measured value is rounded to the second decimal place).
ME = D / D ₀

[Polymerization method]
Moreover, the high pressure radical process low density polyethylene resin (A) in this invention is manufactured on the following conditions by the radical polymerization method.

(I) Polymerization conditions The high-pressure radical polymerization method of the present invention is produced by bulk or solution polymerization under ultrahigh pressure in the presence of a radical initiator such as oxygen or organic peroxide.
The polymerization temperature is 100 to 300 ° C, preferably 120 to 280 ° C, more preferably 150 to 250 ° C. If the polymerization temperature is less than 100 ° C, the yield may be lowered or a stable product may not be produced. If the polymerization temperature is more than 300 ° C, the reaction is not stabilized and it is difficult to obtain a polymer having a large molecular weight. The polymerization pressure is 50 to 400 MPa, preferably 70 to 350 MPa, more preferably 100 to 300 MPa. If the polymerization pressure is less than 50 MPa, a product having a sufficient molecular weight cannot be obtained, resulting in deterioration of workability and physical properties. When the pressure exceeds 400 MPa, stable production operation is difficult to perform.

(Ii) Polymerization Operation For production, basically, production equipment and technology for ordinary high-pressure radical process low-density polyethylene can be used. As the type of reactor, an autoclave type with a stirring blade or a tubular type can be used, and if necessary, a plurality of reactors can be connected in series or in parallel to perform multistage polymerization. . Furthermore, in the case of an autoclave type reactor, it is possible to provide temperature distribution or to perform more precise temperature control by dividing the inside of the reactor into a plurality of zones. By such an operation, it is possible to control a memory effect or the like.

(Iii) Radical initiator As the radical initiator, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2 , 5-Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, lauroyl peroxide, t-butylperoxy Benzoate, 1,1,3,3-tetramethylbutyl hydroperoxide, diisopropylbenzene hydroperoxide, t-butylcumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, di t-Butyldiperoxyisophthalate, n-butyl-4,4-bis (t-butylperoxy) Valerate, t-butyl peroxybenzoate, t-butyl peroxyacetate, cyclohexanone peroxide, t-butyl peroxylaurate, acetyl peroxide, i-butyl peroxide, octanoyl peroxide, t-butyl peroxypivalate , T-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, 1,1-bist-butylperoxycyclohexane, 2,2-bist -Organic peroxides such as butyl peroxyoctane and 2,2-azobisisobutyronitrile. Among these, a decomposition temperature for obtaining a half-life of 1 minute is preferably 160 to 200 ° C.

(Iv) Compounding amount of radical generator The compounding amount of the radical generator is not particularly limited, but is 0.1 to 5 parts by weight, preferably 0.3 to 3 parts by weight, more preferably 100 parts by weight of polyethylene. The range is 0.5 to 2 parts by weight. If necessary, the molecular weight may be adjusted using a chain transfer agent or the like.

(V) Examples of the chain transfer agent chain transfer agent, hydrogen, propylene, butene _-1, C 1 _{-C 20} or more saturated aliphatic hydrocarbons or halogenated hydrocarbons, such as methane, ethane, propane, butane, isobutane, n- hexane, n- heptane, cycloparaffins, chloroform, carbon _{tetrachloride,} C 1 _{-C 20} or more saturated aliphatic alcohols, such as methanol, ethanol, propanol and _isopropanol, C 1 _{-C 20} or even The above saturated aliphatic carbonyl compounds such as acetone and methyl ethyl ketone, and aromatic compounds such as toluene, diethylbenzene and xylene are mentioned.

(1-2) High-pressure radical method low-density polyethylene resin (B)
Unlike the high-pressure radical method low-density polyethylene resin (A), the high-pressure radical method low-density polyethylene resin (B) is (b1) a melt flow rate measured according to JIS K7210 (190 ° C., 21.18 N load) ( MFR (b)) satisfies 2 to 70 g / 10 min, (b2) the test temperature is 23 ° C., and the density measured according to JIS-K7112 is 0.905 to 0.940 g / cm ³ or less. The production method is the same as that of the high-pressure radical method low-density polyethylene resin (A), and is produced by appropriately changing the polymerization conditions so that the characteristics satisfy the above.

(B1) MFR
The high-pressure radical method low-density polyethylene resin (B) has an MFR (b) measured in accordance with JIS K7210 (190 ° C., 21.18 N load) of 2-70 g / 10 min, preferably 3-65 g / 10 min, more preferably. Is in the range of 4-60 g / 10 min. The high pressure radical process low density polyethylene resin (B) can be said to be a component for improving the MFR with respect to the high pressure radical process low density polyethylene resin (A). When the MFR (b) is less than 2 g / 10 min, it is extruded. High-speed workability at the time of laminating deteriorates, which is not preferable. Moreover, since MFR (b) exceeds 70 g / 10min, there exists a possibility that extrusion lamination processability may become unstable, and is unpreferable.

(B2) Density The high-pressure radical method low-density polyethylene resin (B) has a test temperature of 23 ° C. and a density according to JIS-K7112 of 0.905 to 0.940 g / cm ³ , preferably 0.907 to 0.937 g. / Cm ³ , more preferably in the range of 0.910 to 0.935 g / cm ³ . If the density is less than 0.905 g / cm ³ , the laminate molding resin does not slide well, and handling becomes worse. Moreover, what a density exceeds 0.940 g / cm < ³ > becomes a thing which is difficult to manufacture industrially.

(1-3) Polyethylene resin composition (C)
The polyethylene resin composition (C) of the present invention is a mixture of the high-pressure radical method low-density polyethylene resin (A) 10 to 90% by weight and the high-pressure radical method low-density polyethylene resin (B) 90 to 10% by weight. (C1) MFR (c) measured according to JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 30 g / 10 min, (c2) Test temperature 23 ° C., density 0 according to JIS-K7112 .905 to 0.940 g / cm ³ , and (c3) Memory Effect (ME) satisfies 1.5 or more.

(C1) MFR
The polyethylene resin composition (C) has an MFR (c) measured in accordance with JIS K7210 (190 ° C., 21.18 N load) of 0.1-30 g / 10 min, preferably 0.3-28 g / 10 min, more preferably 0.5 to 25 g / 10 min. If MFR (c) is less than 0.1 g / 10 min, the high-speed processability at the time of extrusion lamination is poor, and the foamed cell may not become large. Moreover, when MFR (c) exceeds 30 g / 10min, the process stability at the time of extrusion lamination will worsen, and there exists a possibility that a foaming cell may burst.

(C2) Density The density of the polyethylene resin composition (C) is 0.905 to 0.940 g / cm ³ , preferably 0.907 to 0.937 g / cm ³ , more preferably 0.910 to 0.935 g. / Cm ³ range. When the density is less than 0.905 g / cm ^3, it is not preferable because the laminate molding resin does not slide and handling becomes worse. Moreover, what a density exceeds 0.940 g / cm < ³ > becomes a thing which is difficult to manufacture industrially.

(C3) Memory effect (ME)
The polyethylene resin composition (C) has a memory effect (ME) of 1.5 or more, preferably 1.6 or more, more preferably 1.7 or more. When the ME is within the above range, the height of the foamed cell can be sufficiently increased, and the neck-in during processing such as extrusion lamination does not increase, so that the workability is stable. In particular, when the memory effect (ME) is less than 1.5, the foamed cells are not sufficiently high, and uniform foamed cells may not be obtained.

[Blend ratio of resin (A) and resin (B)]
The blending ratio of the high pressure radical method low density polyethylene resin (A) and the high pressure radical method low density polyethylene resin (B) is 10 to 90% by weight of the high pressure radical method low density polyethylene resin (A), and the high pressure radical method low density polyethylene resin. (B) 10 to 90 wt%, preferably resin (A) 15 to 85 wt% / resin (B) 85 to 15 wt%, more preferably resin (A) 20 to 80 wt% / resin (B) It is in the range of 80 to 20% by weight.
When the resin (A) is less than 10% by weight and exceeds 90% by weight of the resin (B), or when the resin (A) is more than 90% by weight and less than 10% by weight of the resin (B), a polyethylene resin Inconveniences such as inability to adjust various physical properties of the composition (C) occur, and as a result, the neck-in at the time of extrusion laminating is large, and inconveniences such as poor stability at the time of processing occur.

In the present invention, the relationship between the MFR (a) of the high-pressure radical low-density polyethylene resin (A) and the MFR (b) of the high-pressure radical low-density polyethylene resin (B) is represented by the following formula (1), preferably (1-1) More preferably, it is desirable to combine the two so as to satisfy the formula (1-2).
MFR (b) / MFR (a)> 1 ----- Formula (1)
MFR (b) / MFR (a)> 2 ----- Formula (1-1)
MFR (b) / MFR (a)> 2.5 ----- Formula (1-2)
In particular, the high pressure radical process low density polyethylene (A) has a lower MFR and higher ME than the high pressure radical process low density polyethylene (B), and the high pressure radical process low density polyethylene (B) is a high pressure radical process low density polyethylene (A). A higher MFR is desirable.
By satisfying such a relationship, the moldability at the time of laminate molding becomes smoother, and the loss due to neck-in is greatly improved.

In the polyethylene resin composition (C) of the present invention, the MFR (c) and the memory effect (ME) further satisfy the following formula (2), preferably the formula (2-1), more preferably the formula It is desirable to satisfy (2-2).
−0.467 × Ln (MFR (c)) + 2.75 ≦ ME −−−−− Formula (2)
(Where Ln is the natural logarithm)
−0.467 × Ln (MFR (c)) + 2.77 ≦ ME −−−−− Formula (2-1)
−0.467 × Ln (MFR (c)) + 2.79 ≦ ME −−−−− Formula (2-2)
When ME does not satisfy the condition of −0.467 × Ln (MFR (c)) + 2.75 ≦ ME in the formula (2), there is a possibility that the foamed cell may not be sufficiently high under the usual processing conditions. In addition, there is a concern that the neck-in during processing such as extrusion lamination becomes large, and the workability may become unstable.

  The melting point of the polyethylene resin composition (C) of the present invention is desirably selected in the range of 80 to 120 ° C, preferably in the range of 90 to 110 ° C. It is possible to adjust the thickness appropriately.

In the present invention, phenolic and phosphorus antioxidants, neutralizers such as metal soap, antiblocking agents, lubricants, dispersants, pigments, as long as the properties of the polyethylene resin composition (C) are not impaired. Additives such as coloring agents such as dyes, antifogging agents, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents may be blended. Further, radical polymerization ethylene (co) polymers such as ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer, in a range not impairing the characteristics of the polyethylene resin composition, density 0.86-0. 91g / cm ³ less than the very low density polyethylene, density 0.91~0.94g / cm ³ less than the linear low density polyethylene, density 0.94 g / cm ³ or more of high-density polyethylene, other polypropylene A polyolefin resin or the like may be blended.

2. The foamable laminate and its production The foamable laminate of the present invention is a laminate in which a polyethylene resin layer (I) is formed on at least one surface of a base material mainly composed of paper by an extrusion laminating method or the like. Preferably, it is a laminate in which a thermoplastic resin layer (II) for holding vapor released from the substrate is formed on the other surface of the substrate, and at least by water vapor released from the substrate Although it is a laminate capable of foaming the polyethylene resin layer (I), other layers may be provided between the outermost layer and the interlayer of the laminate as long as the effects of the present invention are not impaired.

(2-1) Base material mainly composed of paper In the present invention, the base material mainly composed of paper is (i) paper or (ii) previously coated on paper with a substance that generates volatile gas by heating. Coated substrate with a substance that generates volatile gas by heating between paper and polyethylene resin layer (I) in the laminate molding process, (iii) volatile gas is heated by heating into the substrate mainly composed of paper It means any of the base materials mixed with the generated substance.
In the present invention, the polyethylene resin layer (I) on the surface of the base material is foamed by the action of water vapor generated mainly by heating of water contained in the paper. There is no particular limitation as long as it can foam the polyethylene resin layer (I) on the surface.
Examples of the above (i) paper include high-quality paper, craft paper, art paper, recycled paper, synthetic paper, sheets containing inorganic substances such as resin and zeolite, and calcium carbonate. The basis weight of the paper is preferably 100 to 400 g / m ² , particularly 150 to 350 g / m ² . The water content of the paper is 4 to 15%, preferably 5 to 13%, more preferably about 5 to 12%.
Examples of the base material obtained by coating (ii) paper with a substance that generates volatile gas by heat include a base material obtained by coating paper with solvent-based ink, water-soluble ink, paint, or adhesive. For example, as can be seen in Japanese Patent Application Laid-Open No. 2000-238225, etc., if an adhesive layer to which a foamable material is added is provided between the base material and the polyethylene resin layer (I), it is generated from the foamable material generated by heating. Volatile gas can promote foaming of the polyethylene resin layer (I) on the substrate surface.
Further, (iii) as a base material in which a substance that generates volatile gas by heating is mixed in the base material, an inorganic or organic foaming agent, a water-containing polymer as a substance that generates volatile gas in the base material, A base material in which microcapsules or the like encapsulating a foaming agent are blended, and a paper made by adding a thermal foaming foaming agent in a papermaking process, as seen in, for example, JP-A-2002-145239, or Examples thereof include microcapsules that encapsulate a foaming agent in paper, and substrates that contain water-absorbing polymers containing water.
Furthermore, a picture, a character, a pattern, etc. can also be printed on paper, such as a pulp paper and a synthetic paper, with an ink etc. on the base material mainly made of paper.

(2-2) Polyethylene resin layer (I)
In the present invention, the polyethylene resin layer (I) is a polyethylene resin composition comprising a mixture of two kinds of the high-pressure radical method low-density polyethylene resin (A) and the high-pressure radical method low-density polyethylene resin (B) on a substrate. Using (C), it is formed by laminate molding or the like, supplied as a foamable laminate, and foamed by at least water vapor or the like released from a substrate mainly composed of paper by heating.
Accordingly, the polyethylene resin composition (C) has a melting point in the range of 80 to 120 ° C., preferably in the melting point range of about 90 to 110 ° C., in order to form a uniform foam cell with a high expansion ratio. It is desirable to do.

  The thickness of the polyethylene resin layer (I) is not particularly limited, but is usually 20 to 100 μm, and 30 to 100 μm is preferable in terms of increasing the thickness of the foam layer. If the thickness of the polyethylene resin layer (I) is less than 20 μm, there is a risk of bursting during foaming, and if it exceeds 100 μm, the thickness of the foamed layer may not be sufficiently increased.

(2-3) Thermoplastic resin layer (II)
The thermoplastic resin layer (II) used in the present invention has a role of retaining vapor released from the base material. The thermoplastic resin (D) constituting it is not particularly limited as long as it has a melting point higher than that of the polyethylene resin composition (C) forming the polyethylene resin layer (I) or does not melt. In order to preferentially foam the polyethylene resin layer (I) and easily obtain a uniform and high cell thickness, the polyethylene resin composition (C) foamed by steam or the like released from the substrate by heating, It is desirable that the difference in melting point from the thermoplastic resin (D) that holds the vapor released from the base material satisfies the following formula (3).
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): Melting point (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): Thermoplastic resin of layer (II) that retains vapor and the like in the substrate (D ) Melting point (° C))

  The thermoplastic resin (D) used in the present invention has 2 to 10 carbon atoms such as high / medium / low density polyethylene, polypropylene resin, polybutene-1 resin, poly-4-methyl-pentene-1 resin, and the like. α-olefin homopolymers or polyolefin resins such as their mutual copolymers, polyamide resins, polyester resins, saponified ethylene-vinyl acetate copolymers, vinyl chloride resins, vinylidene chloride resins, polystyrene resins, or Examples thereof include a mixture thereof. Among these, polyolefin resins such as high density polyethylene, medium density polyethylene, and linear low density polyethylene are preferable.

Moreover, when employ | adopting polyolefin resin as a thermoplastic resin (D), MFR is 0.1-100 g / 10min, Preferably it is 0.3-80 g / 10min, More preferably, it is 0.5-60 g / 10. Minutes and densities of 0.920 to 0.970 g / cm ³ , preferably 0.925 to 0.960 g / cm ³ , more preferably about 0.930 to 0.950 g / cm ³ are preferable.
In consideration of the polyethylene resin layer (I), the melting point Tm (D) is desirably selected in the range of 100 ° C. or higher, preferably 110 ° C. to 140 ° C., more preferably 115 ° C. to 140 ° C. Here, the melting point Tm (D) is a melting point of the highest peak height in the second scanning melting point measured by DSC.
If the melting point is lower than 100 ° C, the heat resistance is insufficient and the thermoplastic resin layer (II) may foam, and if it exceeds 140 ° C, the low-temperature heat sealability may be poor. Therefore, it is not preferable.

  In addition, in the case of using a resin having poor adhesion to the paper substrate such as polyamide resin, polyester resin, saponified ethylene-vinyl acetate copolymer, vinyl chloride resin, vinylidene chloride resin, polystyrene resin, It is good also as a laminated body through usual adhesive resin etc., such as a copolymer with unsaturated carboxylic acid modified polyolefin resin and ethylene-unsaturated carboxylic acid.

  In the above thermoplastic resin, as necessary, the antioxidants such as phenols and phosphoruss, neutralizers such as metal soaps, antiblocking agents, lubricants, and dispersions, as long as the properties of the thermoplastic resin are not impaired. Additives such as colorants such as agents, pigments and dyes, antifogging agents, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents may be blended.

  The thickness of the thermoplastic resin layer (II) is not particularly limited, but is usually selected in the range of 10 to 100 μm, particularly 20 to 100 μm in that the thickness of the foamed layer can be increased. When the thickness of the thermoplastic resin layer (II) is less than 10 μm, the vapor released from the base material cannot be sufficiently retained, and the foam layer may not be sufficiently thick. On the other hand, when the thickness exceeds 100 μm, further improvement in the effect is not expected, and there is a concern that economic disadvantages are increased.

In the foamed laminate of the present invention, other layers may be provided in the interlayer or the inner layer and / or the outer layer, etc. within a range not impairing the effects of the present invention. For example, {polyethylene film layer / Expandable polyethylene resin layer (I) / base material / thermoplastic resin layer (II)}, {polyethylene film layer / barrier layer / adhesive layer / expandable polyethylene resin layer (I) / base material / thermoplastic resin layer (II )}, Expandable polyethylene resin layer (I) / substrate / thermoplastic resin layer (II) / barrier layer / thermoplastic resin layer (II)} One or more film layers, a decorative layer, a reinforcing layer, an adhesive layer, a barrier layer, and the like may be provided in and / or on the outer layer of the laminate provided with the plastic resin layer (II).
Moreover, you may print etc. as needed. The printing may be performed partially or entirely with colored ink. Moreover, you may provide a foaming site | part partially or entirely using a foamable ink as needed. For the printing position, the size of the printing area, the printing method, the ink used, etc., a conventionally known technique can be appropriately selected and used.

Examples of the decorative layer include printed paper, film, nonwoven fabric, and woven fabric.
The reinforcing layer is a polyethylene resin film on the outer layer of the foamable polyethylene resin layer (I) so that the foamable polyethylene resin layer (I) laminated on the substrate is not foamed by heating. To prevent bursting due to excessive foaming of the foamed layer, to uniformly correct uneven foamed cells, or to laminate films, nonwoven fabrics, etc. to give mechanical strength. . The resin is not particularly limited, and may be a polyolefin resin such as polyethylene or polypropylene, a polyamide resin, a polyester resin, or the like.
Examples of the resin forming the adhesive layer include a copolymer of ethylene and an unsaturated carboxylic acid or a derivative thereof, a modified polyolefin resin obtained by grafting an unsaturated carboxylic acid on a polyolefin resin, an ethylene-vinyl acetate copolymer, etc. A hot melt, a normal adhesive, etc. are mentioned.
As the resin for forming the barrier layer, polyamide resin, polyester resin, ethylene-vinyl acetate copolymer saponified product (EVOH), polyvinylidene chloride resin, polycarbonate resin, stretched polypropylene (OPP), stretched polyester ( OPET), stretched polyamide, alumina vapor deposition film, inorganic oxide vapor deposition film such as silica vapor deposition film, metal vapor deposition film such as aluminum vapor deposition, and metal foil.

(2-4) Method for producing foamable laminate In the present invention, as a method for producing the foamable laminate, the polyethylene resin layer (I) is laminated on one side of a substrate mainly composed of paper, or the other The method is not particularly limited as long as the thermoplastic resin layer (II) can be further laminated on the surface. However, the extrusion laminating process for directly laminating the molten resin, the sand laminating process for laminating the film in advance, and the dry laminating process. And the like.

Extrusion laminating is a molding method in which a molten resin film extruded from a T-die is continuously coated and pressure-bonded on a substrate, and coating and adhesion are performed simultaneously. Sand laminating is a method in which a molten resin is poured between paper and a film to be laminated, and the molten resin acts as an adhesive to bond and laminate. Dehumidify the ambient humidity in the vicinity of the adhesive and / or adhesive application roll that bonds the film to be laminated with, or heat the temperature of the adhesive and / or adhesive application roll, or paste the film sheet This is a method of drying the surface.
In the sand laminating process and the dry laminating process, on the side on which the thermoplastic resin layer (II) of the paper-based base material used in the present invention is formed, between the base material and the thermoplastic resin layer (II). In order to improve the barrier property, it is easy to laminate the aluminum foil, polyester film, various barrier films and the like.

3. Foamed paper The foamed paper of the present invention is obtained by heating the foamable laminate and foaming the polyethylene resin layer (I). That is, when foaming the foamable laminate, the polyethylene resin layer (I) and the thermoplastic resin layer (II) that retains vapor released from the base material satisfy the following (formula 3): Preferably it is done.
Here, maintaining vapor etc. released from the base material means that the vapor etc. released from the base material under a predetermined heating condition is diffused to the polyethylene resin layer (I) side, and the polyethylene resin layer (I) is preferentially used. This refers to barriering vapor or the like so as to foam. When the thermoplastic resin used for the thermoplastic resin layer (II) is selected so as to satisfy this formula (3), the foaming treatment conditions by heating can be broadened, and the polyethylene resin layer (I) is preferentially foamed. This is preferable.
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): Melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): Thermoplastic resin of layer (II) that retains vapor or the like in the substrate ( D) melting point Tm (° C.))

The height of the foam cell of the foam-processed paper is 370 μm or more, preferably 400 μm or more. If the height of the foam cell is less than 370 μm, there is a possibility that sufficient heat insulation cannot be obtained.
The above-mentioned foamed paper is used as a heat insulating and heat insulating material for the following cups, as well as cushioning materials, sound insulation materials, foamed paper, etc., sleeve materials, paper plates, trays, anti-slip materials, fruit packaging Used as agricultural, industrial, and daily life materials such as wood and foamed paper.

Production of foamed paper is the same as the production conditions for the heat insulating container described below, and the heating method is not particularly limited, and examples include hot air, microwave, high frequency, infrared, and far infrared.
There is no particular limitation on the heating temperature, but it must be a temperature at which moisture in the substrate mainly composed of paper is evaporated and the foamed layer resin is melted. In the present invention, it is 100 to 200 ° C., preferably 100 -160 degreeC, More preferably, 100-140 degreeC is preferable. The heating time is preferably 10 seconds to 5 minutes. If the heating temperature is less than 100 ° C. and the heating time is less than 10 seconds, a sufficiently high foam cell may not be obtained. In the case of excessive heating such that the heating temperature exceeds 200 ° C. or the heating time exceeds 5 minutes, the sag and uniformity of the foamed cells may be impaired.

4). Thermal insulation container The thermal insulation container of the present invention is obtained by forming a container using the foamable laminate and then heating the container to foam the polyethylene resin layer (I).
Even in the heat insulating container, like the foamed paper, the height of the foamed cell is preferably 370 μm or more, and preferably 400 μm or more. If the height of the foam cell is less than 370 μm, there is a possibility that sufficient heat insulation cannot be obtained.
The insulated container obtained by this is used as a tray, a cup, etc. Applications include hot beverage containers, cup soup containers, cup miso soup containers, cup noodle containers, natto containers, lunch boxes, coffee cup containers, and the like.

5. Method for manufacturing a heat insulating container The above heat insulating container, particularly a method for manufacturing a cup, is released from a base material by heating using at least one surface of a base material mainly made of paper using a polyethylene resin composition (C). A polyethylene resin layer (I) having a thickness of 20 to 100 μm that is foamed by steam or the like is formed, and the thermoplastic resin (D) is used on the other surface of the substrate to hold the vapor or the like released from the substrate. Forming a foamable laminate on which a thermoplastic resin layer (II) having a thickness of 10 to 100 μm is formed, then forming into a container, and then heating at a heating temperature of 100 to 200 ° C. to release steam from the substrate The polyethylene resin layer (I) is foamed by the method described above.
The method for manufacturing a heat insulating container is basically the same as the method for manufacturing foamed paper. In order to laminate on the base material, a usual laminating method is applied. In the extrusion lamination, the resin temperature immediately below the die is 200 to 350 ° C, preferably 260 to 350 ° C, more preferably 270 to 350 ° C. The molding speed is 10 to 400 m / min, preferably about 10 to 350 m / min, and if necessary, in order to improve the adhesion between the base material and the polyethylene resin, corona discharge treatment, ozone treatment, Plasma treatment, flame treatment, or the like may be performed. Moreover, you may apply | coat an anchor coating agent as needed.
The foamed laminate produced in this way is rolled out or continuously drawn out, and a blank for a trunk member and a blank for a bottom plate member are punched out from the foamed laminate, and a barrel member is used with a conventional cup molding machine. After the bottom plate members are joined and molded into a cup shape, etc., they are transported to a batch or transfer belt conveyor and heated and foamed in a furnace, oven tunnel, etc. equipped with hot air, microwave, high frequency, infrared, far infrared, etc. A heat insulating container is formed.
In particular, for continuous production, preferably, a polyethylene resin composition (C) that is foamed by steam or the like released from the substrate by heating, and a thermoplastic resin that retains the steam or the like released from the substrate. It is desirable that the melting point difference from (D) satisfies the relationship of the following formula (3).
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): Melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): Thermoplastic resin of layer (II) that retains vapor or the like in the substrate ( D) melting point Tm (° C.))
As a result, high-speed moldability such as extrusion lamination is good, it is possible to continuously form a foam layer having a high foaming ratio and uniform foam cells, good appearance, good printability and productivity. improves. The heating time is preferably 10 seconds to 5 minutes. If the heating temperature is less than 100 ° C. and the heating time is less than 10 seconds, a sufficient foamed cell height may not be obtained. In addition, when the heating temperature exceeds 200 ° C. and / or the heating time exceeds 5 minutes, the generated foamed cell becomes excessively heated, causing the foamed cell to sag and the like, which causes variation in products. There is a fear.
Thus, in the production method of the present invention, by using a composition comprising a low MFR and high ME high pressure radical method low density polyethylene resin (A) and a high MFR high pressure radical method low density polyethylene resin (B), Formability during extrusion laminating, low loss, high foaming ratio, a foamed layer with uniform foamed cells formed, and easy to obtain a heat-insulating container with excellent heat insulation, good appearance, etc. be able to.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In addition, the test methods of the polyethylene resin used in the present Example, its physical properties, the obtained foamed laminate, and the like are as follows.

(1) MFR: Measured according to JIS K7210 (190 ° C., 21.18 N load).
(2) Density: The pellets were hot-pressed to prepare a press sheet having a thickness of 2 mm. The sheet was placed in a beaker having a capacity of 1000 ml, filled with distilled water, covered with a watch glass, and heated with a mantle heater. After boiling boiling water for 60 minutes, the beaker was placed on a wooden table and allowed to cool. At this time, the boiling distilled water after boiling for 60 minutes was adjusted to 500 ml so that the time until reaching room temperature was not less than 60 minutes. Moreover, the test sheet was immersed in the substantially center part in water so that it might not contact a beaker and the water surface. The sheet was annealed at a temperature of 23 ° C. and a humidity of 50% within a period of 16 hours or more and within 24 hours, then punched out to a length of 2 mm and measured at a test temperature of 23 ° C. according to JIS-K7112.

(3) Memory effect (ME): Measured using a melt indexer (semi-automatic ME meter manufactured by Misuzu Erie Co., Ltd.) used in JIS K7210.
<Measurement conditions>
The conditions were as follows under conditions of a cylinder temperature of 240 ° C. and a constant speed extrusion rate of 3 g / min.
A 2.095 mmφ MFR measurement nozzle is set in the apparatus, and the furnace is filled with resin. Place the piston, hold at 0.09 g / min constant speed extrusion for 5 minutes, then perform 3 g / min constant speed extrusion and release air until 6 minutes 30 seconds. After 6 minutes and 30 seconds, the strand was cut while maintaining 3 g / min. The diameter of the strand when the strand length from the lower end of the orifice became 20 mm was measured at 15 mm from the lower end of the orifice. Measure using a measuring instrument (LS-3033). The measured strand diameter was D and the orifice diameter of the die was D ₀ (2.095 mm), and ME was determined by the following formula (however, the measured value was rounded to the second decimal place).
ME = D / D ₀

(4) Melting point: The pellet was formed into a sheet by hot pressing, and punched out to obtain a sample. The measurement was carried out under the following conditions under the procedure of first temperature rise, temperature drop, and second temperature rise, and the temperature at the maximum peak height of the second temperature rise was taken as the melting point.
Apparatus: DSC220 manufactured by Seiko Instruments Inc.
Temperature raising / lowering conditions: First temperature rise from 30 ° C to 200 ° C at 40 ° C / min
Temperature drop 10 ° C / min from 200 ° C to 20 ° C
Second temperature increase from 20 ° C. to 200 ° C. at 10 ° C./min Temperature holding time: 5 minutes after first temperature increase, 5 minutes after temperature decrease Sample amount: 5 mg
Reference: Aluminum

(5) Workability (molten film stability): When the polyethylene resin layer (I) was extrusion laminated, it was visually evaluated whether the processing could be performed stably.
○: The molten film is stable and can be processed.
X: The molten film is unstable and it is impossible to collect a sample having a uniform thickness.
(6) Height of foam cell: The thickness of the foam laminate was measured with a dial gauge, and the thickness of the base material and the thermoplastic resin layer (II) was gradually reduced to the foam cell height.
(7) Uniformity of foamed cells: The surface of the foamed laminate was visually observed to evaluate the presence and uniformity of partial excessive foaming.
○: Good, Δ: Cell height is uneven, ×: Cell rupture occurs.

1. Polyethylene resin (1) High pressure radical method Low density polyethylene resin (A)
The raw material resins A1, A2 and A3 are produced in a high pressure radical process low density polyethylene production facility having an autoclave reactor.
The properties are shown in Table 1 below.

(2) High pressure radical method low density polyethylene resin (B)
The raw resin B1 and B4 are manufactured in a high-pressure radical process low-density polyethylene manufacturing facility having a tubular reactor, and the raw resin B2 is manufactured in a high-pressure radical process low-density polyethylene manufacturing facility having an autoclave reactor.
Moreover, raw material resin B3 is a commercial item (Nippon Polyethylene Co., Ltd., brand name: LC522).
The properties are shown in Table 2 below.

2. Thermoplastic resin D1: MFR 10 g / 10 min, density 0.936 g / cm ³ , high-density polyethylene resin having a melting point of 129 ° C. This raw material D1 is a commercially available product (trade name: HC170, manufactured by Nippon Polyethylene Co., Ltd.).

(Examples 1-7)
One side of a paper substrate having a basis weight of 157 g / m ² and a moisture content of 7% is subjected to corona treatment (30 W · min / m ² ), and a thermoplastic resin layer (40 mm extruder, extrusion laminator with an effective die width of 360 mm) is used. II) as a material constituting MFR 10 g / 10 min, density 0.936 g / cm ³ , polyethylene resin (D1) having a melting point of 129 ° C. is extrusion laminated at a resin temperature of 320 ° C., a processing speed of 20 m / min, and a thickness of 20 μm. A laminate of the plastic resin layer (II) and the paper substrate was obtained.
The paper substrate surface opposite to the thermoplastic resin layer (II) of the laminate is subjected to corona treatment (30 W · min / m ² ), and a resin temperature of 320 ° C. using a 40φ extruder and an extrusion laminator having an effective die width of 360 mm. A polyethylene resin composition (C) containing the high-pressure radical polyethylene resins (A) and (B) in the proportions shown in Table 3 as materials constituting the polyethylene resin layer (I) at a processing speed of 20 m / min and a thickness of 40 μm. ) To obtain a foamable laminate comprising a polyethylene resin layer (I), a paper base material, and a thermoplastic resin layer (II). When the polyethylene resin layer (I) was extrusion laminated, the workability (melted film stability) as to whether the processing could be performed stably was evaluated visually.
The obtained foamable laminate was left in an oven at 120 ° C. for 4 minutes, then taken out of the oven and allowed to cool at room temperature to produce foamed paper.
In Examples 1 to 7 that satisfy the above-described constituent requirements of the present invention, the melted film has good processing stability, the foaming is uniform in any of the examples, and the height of the foamed cell exceeds 400 μm. It was. The results are shown in Table 3.

(Comparative Examples 1-2)
A foamable laminate was produced in the same manner as in Example 1 except that the high-pressure radical method low-density polyethylene resins (B1) and (B2) were used alone as the resin constituting the polyethylene resin layer (I). The melt film at the time of the laminate molding process was unstable and the molding processability was poor, and a foamable laminate could not be obtained. The results are shown in Table 3.

(Comparative Example 3)
A foamable laminate was obtained in the same manner as in Example 1 except that the high-pressure radical method low-density polyethylene resin (A2) was used alone as the resin constituting the polyethylene resin layer (I). The obtained foamable laminate was left in an oven at 120 ° C. for 4 minutes, then taken out of the oven and allowed to cool at room temperature to produce foamed paper. The height of the foam cell was as low as 360 μm, and the target height of the present invention was not obtained. The results are shown in Table 3.

(Comparative Example 4)
A foamable laminate was obtained in the same manner as in Example 1 except that a commercially available high-pressure radical polyethylene resin (B3) was used alone as the resin constituting the polyethylene resin layer (I). The obtained foamable laminate was left in an oven at 120 ° C. for 4 minutes, then taken out of the oven and allowed to cool at room temperature to produce foamed paper. The height of the foam cell was as low as 350 μm, and the target height of the present invention was not obtained. The results are shown in Table 3.

(Comparative Example 5)
As a material constituting the polyethylene resin layer (I), a polyethylene resin composition (C) blended with 30% by weight of a high-pressure radical method polyethylene resin (B4) and 70% by weight of a high-pressure radical method polyethylene resin (B1), Extrusion laminating was performed in the same manner as in Example 1, but the molding processability was poor and a foamable laminate could not be obtained. The results are shown in Table 3.

(Comparative Example 6)
As a material constituting the polyethylene resin layer (I), a high-pressure radical method polyethylene resin (A3) 30% by weight and a high-pressure radical method polyethylene resin (B1) 70 wt. Extrusion laminating was carried out in the same manner as in Example 1, but the molding processability was poor and a foamable laminate could not be obtained. The results are shown in Table 3.

(Example 8)
The foam blank made of the polyethylene resin layer (I), the paper base material and the thermoplastic resin layer (II) produced in Example 1 is formed into a body member blank and a bottom plate member blank so that the height is 90 mm and the inner diameter is 70 mm. After punching and joining the body member blank and the bottom plate member blank to form a cup-shaped container, it is left in an oven at 120 ° C. for 4 minutes, taken out from the oven, and allowed to cool at room temperature to be a foamed cup-shaped container Got. The body part of the container was cut out, and the foamability of the polyethylene resin layer (I) was observed in the same manner as in Example 1. The foamed cell was a uniform cell having a height of 450 μm, and the foamed state was good even when molded into a cup container.

Claims (12)

A polyethylene resin composition for a foamable laminate that forms a polyethylene resin layer (I) for foaming on at least one surface of a base material mainly composed of paper,
10% to 90% by weight of the high-pressure radical process low-density polyethylene resin (A) satisfying the following characteristics (a1) to (a3), and the following characteristics (b1) to (b2) other than the resin (A) obtained by mixing the 10 to 90% by weight high-pressure radical process low-density polyethylene resin (B), and a polyethylene resin composition (C) satisfies the following properties (c1) ~ (c3) a mixture Moreover, the MFR (a) of the high-pressure radical method low-density polyethylene resin (A) and the MFR (b) of the high-pressure radical method low-density polyethylene resin (B) satisfy the following formula (1): Polyethylene resin composition for foamable laminate.
(A1) MFR (a) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(A2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(A3) The memory effect (ME) measured using the melt indexer used in JIS K7210 under the conditions of a cylinder temperature of 240 ° C. and a constant speed extrusion rate of 3 g / min is 1.7 or more,
(B1) MFR (b) measured in accordance with JIS K7210 is 2 to 70 g / 10 min.
(B2) The test temperature is 23 ° C., and the density measured according to JIS K7112 is 0.905 to 0.940 g / cm ³ .
(C1) MFR (c) measured according to JIS K7210 is 0.1 to 30 g / 10 min,
(C2) Test temperature 23 ° C., density measured in accordance with JIS K7112 is 0.905 to 0.940 g / cm ³ ,
(C3) Memory effect (ME) measured under the same conditions as (a3) is 1.5 or more
MFR (b) / MFR (a)> 1 ----- Formula (1) The polyethylene resin composition for a foamable laminate according to claim 1, wherein the MFR (c) and the memory effect (ME) of the polyethylene resin composition (C) satisfy the following formula (2).
−0.467 × Ln (MFR (c)) + 2.75 ≦ ME −−−−− Formula (2)
(Where Ln is the natural logarithm) Foam formed by forming a polyethylene resin layer (I) for foaming on at least one surface of a base material mainly composed of paper, using the polyethylene resin composition for foamable laminates according to claim 1 or 2. Laminate. On the other surface of the substrate, by using a thermoplastic resin (D), according to claim 3, characterized in that further form a thermoplastic resin layer (II) to retain the vapor is released from the substrate or the like The foamable laminate described in 1. The foamable laminate according to claim 4 , wherein the polyethylene resin layer (I) has a thickness of 20 to 100 µm, and the thermoplastic resin layer (II) has a thickness of 10 to 100 µm. Polyethylene resin composition and the melting point Tm of (C) (C), the melting point difference between the melting point Tm (D) of the thermoplastic resin (D) is, according to claim 3, characterized by satisfying the following equation (3) The foamable laminated body of any one of -5 .
Tm (D) −Tm (C) ≧ 10 −−−−− Formula (3)
(However, Tm (C): Melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): Melting point Tm (° C.) of thermoplastic resin (D) of layer (II) is there) Foamed paper obtained by heating the foamable laminate according to any one of claims 3 to 6 to foam the polyethylene resin layer (I). The foamed paper according to claim 7 , wherein the foamed cell formed by foaming the polyethylene resin layer (I) has a height of 370 μm or more. A heat insulating container obtained by forming a container using the foamable laminate according to any one of claims 3 to 6 , and then heating the container to foam the polyethylene resin layer (I). It is a cup-shaped container, The heat insulation container of Claim 9 characterized by the above-mentioned. A polyethylene resin layer (I) having a thickness of 20 to 100 μm is formed on at least one surface of a base material mainly composed of paper using the polyethylene resin composition (C) according to claim 1 or 2. The other surface of the substrate is formed using the thermoplastic resin (D) so that the thickness of the thermoplastic resin layer (II) for holding the vapor released from the substrate is 10 to 100 μm, The molded foam laminate is molded into a container, and then heated at 100 to 200 ° C. to foam the polyethylene resin layer (I) with at least steam released from the base material. Production method. The method for producing a heat-insulating container according to claim 11 , wherein the difference in melting point between the polyethylene resin composition (C) and the thermoplastic resin (D) satisfies the following formula (3).
Tm (D) −Tm (C) ≧ 10 −−−−− (3)
(However, Tm (C): melting point Tm (° C.) of polyethylene resin composition (C) of layer (I), Tm (D): melting point Tm (° C.) of thermoplastic resin (D) of layer (II) is there)