JP6375988B2 - Heat-foamable laminate and foamed paper and heat insulating container using the same - Google Patents

Description

  The present invention relates to a heat-foamable laminate using a resin composition excellent in hot slip property at the time of foam molding of a cup and having good workability at the time of laminate molding, and foam-processed paper and a heat insulating container using the same. It is about.

  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 of and has good printability, a heat-insulated paper container using multiple sheets of paper, or a material in which both sides of a paper base material are laminated with a polyethylene resin layer, foam the polyethylene resin layer on the surface, There is a paper container with heat insulation.

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).
On the other hand, a method of improving the expansion ratio of the foam layer by providing a barrier layer that suppresses the permeation of water vapor in the non-foam layer has been devised. From the aluminum foil or stretched polyester film as a barrier layer on the opposite side of the foam layer There is disclosed a method of preventing water vapor permeation at the time of heat foaming while providing a layer to be formed and further providing a sealant layer thereon, while allowing cup molding by heat sealing (see, for example, Patent Documents 3 and 4). ). However, this method has a problem that the layer structure needs to provide a barrier layer and a sealant layer, leading to an increase in cost.

  Furthermore, a method is disclosed in which a non-foamed layer is foamed by using a high-density polyethylene resin having a higher melting point than that of the foamed layer and heating at an intermediate temperature between the two (for example, Patent Documents 5 to 5). 7). However, none of the patent documents describes details of high-density polyethylene. For the production of foamed laminates, extrusion laminate molding methods are widely used to obtain stable quality products with high efficiency. However, high-density polyethylene has unstable processability during extrusion lamination, The simple substance cannot be used for extrusion lamination molding, and is used by mixing high pressure method low density polyethylene. However, in the process of producing a paper container with foamed laminates obtained by this method and imparting heat insulation properties, the hot-slip property of the non-foamed layer is inferior, causing defects during cup production, and reducing production efficiency There was a problem of being connected to.

Japanese Patent Publication No. 48-32283 JP-A-57-110439 JP 2003-261128 A JP 2004231197 A Japanese Patent Laid-Open No. 10-128928 Japanese Patent Laid-Open No. 11-189279 JP 2007-168178 A

  In view of the above problems, an object of the present invention is a heat-foamable laminate having excellent hot-slip properties in a foaming process during cup production and good workability during laminate molding, and foamed paper using the same And providing an insulated container.

  As a result of intensive studies to solve the above problems, the present inventor has a laminate using a specific resin composition for forming a non-foamed layer, has excellent hot-slip properties in the foaming step, and is also suitable for laminate molding. The present inventors have found that the workability is good and have completed the present invention.

That is, according to the first invention of the present invention, a low density polyethylene resin layer (I) for foaming is formed on one side of a base material mainly composed of paper, and the other side of the base material is A heat-foamable laminate in which a thermoplastic resin layer (II) that retains vapor or the like released from a substrate is formed, and the resin composition (II) that forms the thermoplastic resin layer (II) is: Linear high-density polyethylene satisfying the characteristics of (a1) to (a3) (a) Less than 50% by weight and 1% by weight or more, and high-pressure low-density polyethylene resin satisfying the following characteristics (A1) to (A2) ( A) A resin composition obtained by mixing less than 50% by weight and 1% by weight or more, and further, 15% by weight to 35% by weight of a high-pressure method low density polyethylene resin (B) satisfying the following characteristics (B1) to (B2): And a polyethylene resin composition which is a mixture thereof (II) relates to a heat-foamable laminate characterized by satisfying the following properties (II-1) to (II-2).
(A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 20 g / 10 min.
(A2) Test temperature 23 ° C. Density in accordance with JIS-K7112 is 0.960 g / cm ^{3 to} 0.970 g / cm ³
(A3) The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight to the number average molecular weight is 2 or more and 10 or less (A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) 0.1-10g / 10min
(A2) The test temperature is 23 ° C., and the density according to JIS-K7112 is 0.920 g / cm ^{3 to} 0.940 g / cm ^3.
(B1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 10 g / 10 min.
(B2) Test temperature 23 ° C., density according to JIS-K7112 is less than 0.920 g / cm ³ (II-1) MFR measured according to JIS K7210 (190 ° C., 21.18 N load) is 0.1 g / 10min-10g / 10min
(II-2) The test temperature is 23 ° C. and the density based on JIS-K7112 is 0.942 g / cm ³ or less.

According to the second invention of the present invention, the melt mass flow of the high pressure method low density polyethylene (b) comprising the mixture of the high pressure method low density polyethylene (A) and the high pressure method low density polyethylene (B) according to claim 1. The present invention relates to a polyethylene resin composition for a foamable laminate described in the first invention, characterized in that the rate (MFR) is 0.1 g / 10 min to 4.0 g / 10 min.

Furthermore, according to the third aspect of the present invention, the low density polyethylene resin layer (I) has a thickness of 20 to 100 μm, and is composed of linear high density polyethylene (a) and high pressure method low density polyethylene (b). The resin composition (II) having a thickness of 10 to 100 μm relates to the foamable laminate described in the first and second inventions.

According to the fourth aspect of the present invention, the difference in melting point between the melting point Tm (I) of the low density polyethylene resin layer (I) and the melting point Tm (II) of the resin layer (II) is expressed by the following formula ( The present invention relates to a heat-foamable laminate according to any one of the first to third inventions characterized by satisfying 1).
Tm (II) −Tm (I) ≧ 10 −−−−− Formula (1)

Furthermore, according to the 5th invention of this invention, it was obtained by heating the heat-foamable laminated body as described in any one of 1st-4th invention, and was formed by foaming the polyethylene resin layer (I). The present invention relates to foamed paper, wherein the height of the foamed cell is 370 μm or more.

According to a sixth invention of the present invention, according to the first to fourth inventions of the present invention, after forming a container using the foamable laminate, the container is heated to obtain a polyethylene resin layer (I ) Is obtained by foaming.

  According to the present invention, a high-pressure low-density polyethylene resin layer (I) for foaming is formed on one surface of a base material mainly composed of paper, and vapor released from the base material is formed on the other side of the base material. As a raw material for producing a non-foaming thermoplastic resin layer (II) that holds the like, a linear high-density polyethylene (a) having a specific MFR and density of 50% by weight or less, and also having a specific MFR and density By using a resin composition consisting of (b) mixed with a specific ratio of high-pressure low-density polyethylene (A) (B) that is in the range, the processability at the time of laminate molding is good, and further in the foaming step, A heat-foamable laminate having a foamed layer in which the thermoplastic resin layer (II) is excellent in hot slip property and has a high foaming ratio and in which uniform foamed cells are formed can be provided at high speed and with high productivity.

  Below, the low density polyethylene resin layer (I) for foaming by heating of the present invention, the thermoplastic resin layer (II) for retaining vapor released from the substrate, and a foamable laminate using the same The foamed paper, the heat insulating container and the manufacturing method thereof will be described in detail for each item. In the present specification, foaming refers to the property of foaming by heating. Good foaming refers to a state where 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 steam from the paper substrate is a measure. become. Also, the uniformity of foam cell height (good appearance) is taken into account.

1. High pressure low density polyethylene resin layer (I)
As the low density polyethylene resin layer (I) for foaming by heating of the laminate of the present invention, any low density polyethylene resin, for example, a high pressure method low density polyethylene resin, or a high pressure method low density polyethylene resin 90 wt% to A resin layer made of a resin composition obtained by appropriately mixing 10% by weight and 10 to 90% by weight of a linear low density polyethylene resin can be used. The high-pressure low-density polyethylene resin that is particularly preferably used is produced under the following conditions by, for example, high-pressure radical polymerization using ethylene monomer as a raw material.
(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 exceeds 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 In production, basically, production equipment and technology for ordinary high-pressure 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-butylperoxybenzoate, 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 peroxide Valate, t-butyl Idro peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, di 2
-Organic peroxides such as ethylhexyl peroxydicarbonate, 1,1-bis t-butyl peroxycyclohexane, 2,2-bis t-butyl peroxyoctane, 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) Chain transfer agent As the chain transfer agent, hydrogen, propylene, butene-1, C1-C20 or more saturated aliphatic hydrocarbon or halogen-substituted hydrocarbon, for example, methane, ethane, propane, butane, isobutane, n-hexane, n-heptane, cycloparaffins, chloroform, carbon tetrachloride, C1-C20 or higher saturated aliphatic alcohols such as methanol, ethanol, propanol and isopropanol, C1-C20 or higher saturated aliphatic carbonyls Compounds such as acetone and methyl ethyl ketone, and aromatic compounds such as toluene, diethylbenzene and xylene are mentioned.

  In the laminate of the present invention, the MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) of the low density polyethylene used for the high pressure method low density polyethylene resin layer (I) is 0.1 to 30 g / 10 min. If it is in the range, it is preferable because the foamability of the laminate is excellent.

In the laminate of the present invention, the test temperature of the low density polyethylene used for the high pressure method low density polyethylene resin layer (I) is 23 ° C., and the density based on JIS-K7112 can reduce the amount of heat applied when foaming the laminate. Therefore, the range of 0.910 to 0.940 g / cm ³ is preferable.

  In the laminate of the present invention, it is preferable that the memory effect (ME) of the low-density polyethylene used for the high-pressure method low-density polyethylene resin layer (I) is 1.5 or more because the foam has excellent foamability.

[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 orifice diameter of the die is D0 (2.095 mm), and the ME is obtained by the following formula (however, the measured value is rounded to the second decimal place).
ME = D / D0

In the present invention, the high-pressure method low-density polyethylene resin layer (I) is formed on the base material by using the high-pressure radical method low-density polyethylene resin by laminate molding or the like, and is supplied as a foamable laminate. It is foamed by at least water vapor or the like released from a paper-based substrate. Therefore, in order to form a uniform foam cell with a high expansion ratio, the melting point of the polyethylene resin composition may be selected within the range of 80 to 120 ° C, preferably within the melting point range of about 90 to 110 ° C. desirable.

In the present invention, phenolic and phosphorous antioxidants, neutralizing agents such as metal soaps, antiblocking agents, and lubricants within a range that does not impair the properties of the low density polyethylene used in the laminate (I). Additives such as dispersants, colorants such as pigments and dyes, antifogging agents, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents may be blended. In addition, radical polymerization methods such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc., in the range not impairing the characteristics of the low density polyethylene used in the laminate (I) layer. coalescence, density 0.86g ^/ cm ³ ~0.91g ^/ cm 3 less than the very low density polyethylene, density 0.910g ^/ cm ³ ~0.940g ^/ cm 3 less than the linear low density polyethylene, density 0.940g Other polyolefin resins such as medium / high-density polyethylene and polypropylene / cm ³ or more may be blended.

2. Resin composition for resin layer (II) The resin composition constituting the layer (II) of the foamable laminate of the present invention has a vapor or the like released from the substrate on one side of the substrate mainly composed of paper. A polyethylene resin composition for forming the thermoplastic resin layer (II) to be held, wherein the linear high density polyethylene (a) satisfying the following characteristics (a1) to (a3): less than 50% by weight and 1% by weight or more The high-pressure low-density polyethylene resin (A) satisfying the following characteristics (A1) to (A2) other than the resin (a) (A) less than 50% by weight, 1% by weight or more, and the following (B1) to (B2), The polyethylene resin composition (II), which is obtained by mixing 15% to 35% by weight of the high-pressure method low density polyethylene resin (B) satisfying the above characteristics, is the following (II-1) to The characteristic of (II-2) is satisfied.
(A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 20 g / 10 min.
(A2) Test temperature 23 ° C. Density in accordance with JIS-K7112 is 0.960 g / cm ^{3 to} 0.970 g / cm ³
(A3) The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight to the number average molecular weight is 2 or more and 10 or less (A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) 0.1-10g / 10min
(A2) The test temperature is 23 ° C., and the density according to JIS-K7112 is 0.920 g / cm ^{3 to} 0.940 g / cm ^3.
(B1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 10 g / 10 min.
(B2) Test temperature 23 ° C., density according to JIS-K7112 is less than 0.920 g / cm ³ (II-1) MFR measured according to JIS K7210 (190 ° C., 21.18 N load) is 0.1 g / 10min-10g / 10min
(II-2) The test temperature is 23 ° C. and the density based on JIS-K7112 is 0.942 g / cm ³ or less.

  The linear high-density polyethylene (a) used for the thermoplastic resin layer (II) of the present invention was measured according to JIS K7210 (190 ° C., 21.18 N load) (a-1) MFR was 0.1 g / 10 min. A range of ˜20 g / 10 min is preferable in terms of stability during extrusion molding.

In the present invention, the linear high-density polyethylene (a) used for the thermoplastic resin layer (II) has a (a-2) test temperature of 23 ° C. and a density according to JIS-K7112 of 0.960 g / cm ^{3 to} 0.00. It is preferably 970 g / cm ³ . A density of 0.960 g / cm ³ or more is preferred because hot slip properties are improved, moisture hardly permeates during foaming by heating, and a laminate having good expansion ratio and excellent heat resistance can be obtained.

  The linear high-density polyethylene (a) used in the resin composition (II) of the present invention has a weight average molecular weight (Mw) measured by (a-3) gel permeation chromatography (GPC) apparatus. It is preferable that the ratio (Mw / Mn) of the number average molecular weight (Mn) is in the range of 2 to 10 because it is easy to achieve both the strength of the molded product and stable extrusion moldability.

In the present invention, the linear high-density polyethylene (a) used for the resin composition (II) for the foamable laminate is composed of repeating units derived from ethylene, or repeating units derived from ethylene and α having 3 to 8 carbon atoms. -It contains an ethylene-based polymer composed of repeating units derived from olefins. The α-olefin is preferably a linear or branched olefin having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1- Mention may be made of octene, 1-decene. Two or more of them may be used in combination. Among these copolymers, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene-1-octene copolymer are economical. It is preferable from the viewpoint.
The linear high-density polyethylene (a) used for the resin composition (II) for the foamable laminate according to the present invention is not particularly limited to the catalyst, the process, etc., and the book “Polyethylene Technology Reader” (Kazuo Matsuura, By Mikami Naotaka, published by the Industrial Research Committee, 2001 It can be produced by the method described in 1 2 3 to 1 6 0. That is, it can be produced with various polymerization apparatuses, polymerization conditions, and catalysts in each polymerization mode of Ziegler catalyst, single site catalyst, etc., slurry method, solution method, and gas phase method. More specifically, in order to produce the linear polyethylene (a) used for the layer (II), a specific Ziegler-based catalyst or single site such as that described in Japanese Patent Publication No. 555-1440. It can be suitably produced by controlling polymerization conditions such as polymerization temperature and pressure, cocatalyst and the like using a system catalyst.

The high-pressure low-density polyethylene (b) used for the thermoplastic resin layer (II) of the present invention uses at least the following two types of high-pressure low-density polyethylene (A) and (B).
That is, the density in the resin composition constituting the layer (II) is 0.920 g / cm ^{3 to} 0.940 g / cm ³ , the melt mass flow rate (MFR) is 0.1 g / 10 min to 10 g / 10 min. and 1 wt% to less than 50 wt% low density polyethylene (a), a density of less than 0.920 g / cm ^3, preferably a density 0.918 g / cm ³ or less, preferably 0.900 g / cm ³ or more, the melt It is preferably made of low-density polyethylene (B) having a mass flow rate of 0.1 g / 10 min to 10 g / 10 min and a content in the resin composition constituting the layer (II) of 15 wt% to 35 wt%.
The density of the low density polyethylene (A) is 0.920 g / cm ^{3 to} 0.940 g / cm ³ , the melt mass flow rate (MFR) is 0.1 g / 10 min to 10 g / 10 min, and the content ratio is the layer (II). When it is less than 50% by weight and 1% by weight or more in the resin composition to be constituted, stability during extrusion is improved, and hot slip property is also excellent, which is preferable. The low density polyethylene (B) has a density of less than 0.920 g / cm ³ , a melt mass flow rate of 0.1 g / 10 min to 10 g / 10 min, and an addition ratio of 15 wt% to 35 wt% in the resin composition. For example, the stability during extrusion molding is improved, which is preferable.

In the present invention, the resin composition for expandable laminate (II), which is a mixture of linear high-density polyethylene (a) and high-pressure method low-density polyethylene (b) comprising at least two types of (A) and (B) It is preferable that the density is 0.942 g / cm ³ or less and the melt mass flow rate is 0.1 g / 10 min to 10 g / 10 min. When the density of the resin composition (II) for the foamable laminate is 0.942 g / cm ³ or less and the melt mass flow rate is 0.1 g / 10 min to 10 g / 10 min, stability during extrusion molding is improved, and hot Since slip property is also excellent, it is preferable.

  In the present invention, the high pressure low density polyethylene (b) used for the thermoplastic resin composition (II) preferably has a melt mass flow rate (MFR) of 0.1 g / 10 min to 4.0 g / 10 min. A melt mass flow rate (MFR) of 0.1 g / 10 min to 4.0 g / 10 min is preferred because stability during extrusion is improved and hot slip properties are also excellent.

  In the resin composition (II), if necessary, a phenolic or phosphorus antioxidant, a neutralizer such as a metal soap, an antiblocking agent, and the like within a range not impairing the properties of the thermoplastic resin. Additives such as lubricants, dispersants, colorants such as pigments and dyes, antifogging agents, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents may be blended.

[Blend ratio of thermoplastic resin composition (II)]
The blending ratio of the linear high-density polyethylene (a) is less than 50% by weight and 1% by weight or more, preferably 45% by weight or less. When the blending ratio of the linear polyethylene (a) is 50% by weight or more, it is not preferable because problems such as deterioration of workability during extrusion lamination molding occur. The blending ratio of the high-pressure method low-density polyethylene resin (A) is less than 50% by weight and 1% by weight or more, preferably 45% by weight or less. When the blending ratio of the high-pressure method low-density polyethylene resin (A) is 50% by weight or more, it is not preferable because inconvenience such as deterioration of workability at the time of extrusion lamination molding occurs. The compounding ratio of the high-pressure method low-density polyethylene resin (B) is 15% by weight to 35% by weight. When the blending ratio of the high-pressure method low-density polyethylene resin (B) is less than 15% by weight, disadvantages such as deterioration in workability at the time of extrusion lamination molding occur, which is not preferable. When the blending ratio of the high-pressure method low-density polyethylene resin (B) exceeds 35% by weight, the hot slip property is inferior, which is not preferable.

3. Expandable laminate and production thereof The expandable laminate of the present invention is a laminate in which a high-pressure low-density polyethylene resin layer (I) is formed on at least one surface of a paper-based substrate by an extrusion lamination method or the like. A laminated body in which a thermoplastic resin layer (II) that holds vapor released from the base material is formed on the other surface of the base material, preferably released from the base material Although it is a laminate capable of foaming the high-pressure low-density polyethylene resin layer (I) with at least water vapor or the like, there are other layers in the outermost layer, the interlayer, etc. of the laminate as long as the effects of the present invention are not impaired. Also good.

The thickness of the high-pressure method low-density polyethylene resin layer (I) 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. preferable. If 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 thickness may not be sufficiently increased. On the other hand, when the thickness exceeds 100 μm, further improvement of the effect is not expected, and the economic disadvantage may increase.

4). The base material mainly composed of paper In the present invention, the base material mainly composed of paper is (i) paper, or (ii) a base material in which paper is previously coated with a substance that generates volatile gas by heating, laminate In the molding process, a material that generates volatile gas by heating is coated between paper and high-pressure low-density polyethylene resin layer (I), (iii) volatile gas is generated by heating into a paper-based substrate It means one of the base materials blended with the substance to be treated. In the present invention, the moisture contained in the paper is used to foam the high-pressure low-density polyethylene resin layer (I) on the substrate surface by the action of water vapor generated by heating. It is not particularly limited as long as it can foam the high-pressure low-density polyethylene resin layer (I) on the surface of the base material with gas. 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 shown in JP-A-2000-238225 and the like, if an adhesive layer to which a foamable substance is added is provided between the base material and the high-pressure method low-density polyethylene resin layer (I), the foamability generated by heating It is possible to promote foaming of the polyethylene resin layer (I) on the surface of the base material by the volatile gas generated from the substance.
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.

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 / High pressure method low density polyethylene resin layer (I) / base material / thermoplastic resin composition layer (II)}, {polyethylene film layer / barrier layer / adhesion layer / high pressure method low density polyethylene resin layer (I) / base material / Thermoplastic resin composition layer (II)}, high pressure method low density polyethylene resin layer (I) / base material / resin composition layer (II) / barrier layer / thermoplastic resin composition layer (II)} The inner layer and / or the outer layer of the laminate provided with the material and the high-pressure method low-density polyethylene resin layer (I) or the thermoplastic resin composition layer (II), or one or more film layers or decorative layers between the layers , Reinforcement layer, contact Adhesive layer may be provided a barrier layer or the like.
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 layer formed on the outer layer of the foamable polyethylene resin layer (I) so that the foamed layer does not rupture when the high-pressure low-density polyethylene resin layer (I) laminated on the substrate is foamed by heating. Resin film is laminated to prevent the foam layer from bursting due to excessive foaming, uneven foam cells are uniformly corrected, or film, nonwoven fabric, etc. are laminated to give mechanical strength. It is. 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.

5. Method for producing foamable laminate In the present invention, the foamable laminate is produced by laminating the high-pressure low-density polyethylene resin layer (I) on one side of a paper-based substrate, or the other side. There is no particular limitation as long as the method can further laminate the resin composition layer (II), but an extrusion laminating process for directly laminating a molten resin, a sand laminating process for laminating a film in advance, and a dry laminating process. Methods 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, the base material and the thermoplastic resin composition layer (II) are formed on the side on which the thermoplastic resin composition layer (II) of the paper-based base material used in the present invention is mainly formed. In order to improve the barrier property, it is easy to laminate the aluminum foil, polyester film, various barrier films and the like.

6). Foamed paper The foamed paper of the present invention is obtained by heating the foamable laminate and foaming the high-pressure low-density polyethylene resin layer (I). That is, when foaming the foamable laminate, the high-pressure method low-density polyethylene resin layer (I) and the thermoplastic resin composition layer (II) that retains vapor released from the substrate are represented by the following (formula 1 ) Is preferably satisfied.
Here, holding 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 high pressure method low density polyethylene resin layer (I) side, and the high pressure method low density polyethylene is used. This refers to barriering vapor or the like so that the resin layer (I) is preferentially foamed. When the resin composition used for the thermoplastic resin composition layer (II) is selected so as to satisfy the formula (1), the foaming treatment conditions by heating can be widened, and the high pressure method low density polyethylene resin layer (I ) Is preferred because it can be preferentially foamed.
Tm (II) −Tm (I) ≧ 10 −−−−− Formula (1)

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.

7). 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.

8). Method for manufacturing a heat insulating container The above heat insulating container, particularly a method for manufacturing a cup, uses at least one surface of a base material mainly made of paper, a high-pressure low-density polyethylene resin, and a steam released from the base material by heating. A resin composed of a linear high-density polyethylene (a) and a high-pressure method low-density polyethylene (b) on the other surface of the base material formed with a polyethylene resin layer (I) having a thickness of 20 to 100 μm foamed by The composition is used to form a foamable laminate in which a thermoplastic resin layer (II) having a thickness of 10 to 100 μm that retains the vapor released from the substrate is formed, and then molded into a container, and then heated to a temperature. The polyethylene resin layer (I) is foamed by steam or the like released from the substrate by heating at 100 to 200 ° C.
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, it is preferable to hold a high-pressure low-density polyethylene resin layer (I) foamed by steam or the like released from the substrate by heating, and steam or the like released from the substrate. It is desirable that the difference in melting point with the thermoplastic resin layer (II) satisfies the relationship of the following formula (1).
Tm (II) −Tm (I) ≧ 10 −−−−− Formula (1)

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 6 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. or the heating time exceeds 6 minutes, the generated foamed cell becomes excessively heated and may sag in the foamed cell, which may cause variation in products. Arise. Thus, in the production method of the present invention, as a raw material for producing the thermoplastic resin layer (II) that retains the vapor released from the base material, a linear polyethylene having a specific MFR and density of 50% by weight or less. Similarly, by using a resin composition in which MFR and high-pressure low-density polyethylene (A) (B) whose density is in a specific range are mixed in a specific ratio, workability at the time of laminate molding is good, and further foaming is performed. Insulating container excellent in hot-slip property of thermoplastic resin layer (II) in the process, and having a foaming layer having a high foaming ratio and a uniform foamed cell, excellent in heat insulation, good appearance, etc. Can be easily obtained.

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.

MFR
Measured in accordance with JIS K7210 (190 ° C., 21.18 N load).

The density pellet was 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) GPC
Apparatus: Waters GPC (ALC / GPC 150C)
Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
Mobile phase solvent: o-dichlorobenzene Measurement temperature: 140 ° C.
Flow rate: 1.0 ml / min Injection volume: 0.2 ml
Sample preparation: Prepare a 1 mg / mL solution using ODCB (containing 0.5 mg / mL BHT) and dissolve at 140 ° C. for about 1 hour.

(4) Neck-in Modern machinery φ90mm extrusion laminator, die width 560mm, air gap 110mm laminate thickness 30μm, laminate speed 100m / min, laminate thickness 15μ laminate speed 150m / min, die lip resin temperature 320 The laminate was extrusion laminated to kraft paper having a basis weight of 50 g / m 2. The neck-in measured under the above conditions was less than 40 mm, and the one with 40 or more was rated as x.

(5) Using drawdown modern machinery φ90mm extrusion laminator, die width 560mm, air gap 110mm, die lip resin temperature 320 ° C, extruder rotation speed constant 12rpm, basis weight 50g / m2 kraft paper Extruded laminate was formed. Under the above processing conditions, the melted resin film was not broken, and the maximum take-up speed was 100 m / min or more.

(6) A hot-slip test piece is a 65 mm × 65 mm wide metal board (weight: 200 g), which is obtained by extruding and laminating 30 mm thick kraft paper with a basis weight of 50 g / m 2 to 65 mm × length 130 mm. The one that was accurately wound around was used.
Tensile type slip tester manufactured by Tester Sangyo Co., Ltd.
After raising the temperature of the stainless steel plate to the measurement temperature described in the examples and comparative examples, the above-mentioned board is set on the stainless steel plate, and the weight change when the test piece is moved at a pulling speed of 150 mm / min after 10 seconds has passed is charted with a load cell. The measured values obtained were read as static friction coefficient and dynamic friction coefficient by the following formulas.
Coefficient of static friction: Weight when metal board starts moving / Metal board weight dynamic friction coefficient: Average value during 70 mm movement of metal board / Metal board weight Coefficient of static friction at 110 ° C. measured under the above conditions, and A sample having a coefficient of dynamic friction of 0.90 or less was marked with ◯, and a coefficient of 0.91 or more was marked with ×. Furthermore, the thing with a static friction coefficient in 115 degreeC and the dynamic friction coefficient of 1.50 or less was made into (circle), and 1.51 or more was made into x.

(Examples 1-4)
A single-screw extruder having a 40 mmφ screw and a strand die after dry blending linear polyethylene (a) and high-pressure method low-density polyethylene (A) (B) each having the physical properties shown in Table 1 at a predetermined weight ratio (Musashino Machinery Co., Ltd.-MK40) was used to extrude into strands at a set temperature of 190 ° C. and 20 kg / H, and pelletized with a strand cutter. Using this ethylene polymer pellet, various physical properties were evaluated. Moreover, the pellets of the obtained ethylene polymer were used, using a φ90 mm extrusion laminator manufactured by Modern Machinery, with a die width of 560 mm, an air gap of 110 mm, a laminate thickness of 30 μm, a laminate speed of 100 m / min, and a laminate thickness of 15 μlaminate speed of 150 m / min. Under the conditions, the die lip resin temperature was set to 320 ° C., extrusion lamination was performed on kraft paper having a basis weight of 50 g / m 2, and hot slip property, neck-in property, and draw down property were measured.
Further, this ethylene polymer pellet was supplied to a φ90 mm extrusion laminator manufactured by Modern Machinery, extruded from a T-die at a temperature of 320 ° C., and a thickness of 40 μm on one side on a paper substrate having a basis weight of 320 g / m ^2. Extrusion laminate molding was performed (layer II), and the other side (layer I) of the paper substrate of this laminate was MFR 14 g / 10 min, density 0.918 g / cm ³ high pressure method low density polyethylene (Product name: Novatec LC701 manufactured by Nippon Polyethylene Co., Ltd.) was extruded and laminated to a thickness of 70 μm. The obtained laminate was cut into 10 cm × 10 cm and allowed to stand for 360 seconds in a perfect oven (PH-102 type Espec) heated to 120 ° C. to foam the high-pressure method low-density polyethylene layer (I layer) side. Then, it was taken out and cooled to room temperature in air. The foamed cell size was measured with a digital microscope (HDM-2100, manufactured by SCARA) from the bottom, and after measuring the area of all the foam cells of 1.3 cm × 1.3 cm square, the average was calculated. An average value of 0.8 or more was evaluated as poor appearance (x), and an average value of less than 0.8 was evaluated as good appearance.
The results are shown in Table 1.

(Comparative Example 1)
Among the high-pressure method low-density polyethylene (b) used for the thermoplastic resin layer (II), the low-density polyethylene (A) has a low-density polyethylene density of 0.918 g / cm ³ and a blending ratio of 60% by weight. The composition MFR of linear polyethylene (a) and high-pressure low-density polyethylene (b), which is 11.1 g / 10 min, is supplied to a modern machinery φ90 mm extrusion laminator, die width 560 mm, air gap 110mm laminating thickness 30μm, laminating speed 100m / min, laminating thickness 15μ laminating speed 150m / min, die lip resin temperature 320 ° C, extrusion laminating to 50g / m ² basis weight kraft paper, hot slip And neck-in and draw-down properties were measured.
The evaluation results are shown in Table 2.

(Comparative Example 2)
The MFR of the linear polyethylene (a) used for the thermoplastic resin layer (II) is 21 g / 10 min, and the high-density low-density polyethylene (b) has a low-density polyethylene blending ratio of 55% by weight. The composition excluding polyethylene (B) was supplied to a φ90 mm extrusion laminator manufactured by Modern Machinery, under the conditions of a die width of 560 mm, an air gap of 110 mm, a laminate thickness of 30 μm, a laminate speed of 100 m / min, and a laminate thickness of 15 μm and a laminate speed of 150 m / min. Then, the die lip resin temperature was set to 320 ° C., and extrusion lamination was performed on a kraft paper having a basis weight of 50 g / m ² to measure hot slip property, neck-in property, and draw down property.
The evaluation results are shown in Table 2.

(Comparative Example 3)
Of the high-pressure low-density polyethylene (b) used for the thermoplastic resin layer (II), the low-density polyethylene (A) has a low-density polyethylene density of 0.918 g / cm ³ and a blending ratio of 20% by weight. A composition in which the density of the linear polyethylene (a) is 0.966 g / cm ³ and the blending ratio is 80% by weight is supplied to a modern machinery φ90 mm extrusion laminator, and the die width is 560 mm and the air gap is 110 mm laminate. Under the conditions of a thickness of 30 μm, a laminating speed of 100 m / min, and a laminating thickness of 15 μlaminating speed of 150 m / min, the die lip resin temperature is set to 320 ° C., and extrusion laminating is performed on kraft paper having a basis weight of 50 g / m ^2. Neck-in and draw-down properties were measured.
The evaluation results are shown in Table 2.

Claims (6)

Thermoplastic that forms a low-density polyethylene resin layer (I) for foaming on one side of a paper-based base material, and holds vapor released from the base material on the other side of the base material A heat-foamable laminate having a resin layer (II), the resin composition (II) forming the thermoplastic resin layer (II) satisfying the following characteristics (a1) to (a3): High-density polyethylene resin (A) less than 50% by weight and 1% by weight or more, and high pressure method low density polyethylene resin (A) satisfying the following characteristics (A1) to (A2): A polyethylene resin composition (II) which is a resin composition in which 15% by weight to 35% by weight of a high-pressure method low density polyethylene resin (B) satisfying the characteristics of (B1) to (B2) is mixed. ) Are the features of (II-1) to (II-2) below. Heating the foamable laminate which satisfies the.
(A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 20 g / 10 min.
(A2) Test temperature 23 ° C. Density in accordance with JIS-K7112 is 0.960 g / cm ^{3 to} 0.970 g / cm ³
(A3) The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight to the number average molecular weight is 2 or more and 10 or less (A1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) 0.1-10g / 10min
(A2) The test temperature is 23 ° C., and the density according to JIS-K7112 is 0.920 g / cm ^{3 to} 0.940 g / cm ^3.
(B1) MFR measured in accordance with JIS K7210 (190 ° C., 21.18 N load) is 0.1 to 10 g / 10 min.
(B2) Test temperature 23 ° C., density according to JIS-K7112 is less than 0.920 g / cm ³ (II-1) MFR measured according to JIS K7210 (190 ° C., 21.18 N load) is 0.1 g / 10min-10g / 10min
(II-2) The test temperature is 23 ° C. and the density based on JIS-K7112 is 0.942 g / cm ³ or less. The melt mass flow rate (MFR) of the high pressure method low density polyethylene (b) obtained when the high pressure method low density polyethylene resin (A) according to claim 1 and the high pressure method low density polyethylene resin (B) according to claim 1 are mixed. ), characterized in that a 0.1g / 10min~4.0g / 10min, claim 1 foamable laminate according.   The thickness of the low-density polyethylene resin layer (I) is 20 to 100 μm, and the thickness of the thermoplastic resin layer (II) composed of linear high-density polyethylene (a) and high-pressure method low-density polyethylene (b). The heat-foamable laminate according to claim 1, wherein the thickness is 10 to 100 μm. The melting point difference between the melting point Tm (I) of the low density polyethylene resin layer (I) and the melting point Tm (II) of the thermoplastic resin layer (II) satisfies the following formula (1): The heat-foamable laminate according to any one of claims 1 to 3.
Tm (II) −Tm (I) ≧ 10 −−−−− Formula (1)   The height of the foamed cell obtained by heating the heat-foamable laminate according to any one of claims 1 to 4 and foaming the polyethylene resin layer (I) is 370 µm or more. Foamed paper characterized by   The heat insulation container obtained by forming a container using the heat-foamable laminated body of any one of Claims 1-4, heating this container and foaming a polyethylene resin layer (I).