JP2000052505A - Easily unsealable container and member used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate leakage of a content in transporting or the like by blend ing a polystyrene resin having a specific composition with a polyolefin resin or forming it in a single layer or multilayer structure, and disposing it at a suitable position thereby easily manually releasing a cover and taking out the content. SOLUTION: A multilayer sheet made of two or more layers is molded to constitute a container. At least one surface layer of the sheet is constituted of a resin composition containing 1 to 96 wt.% of polystyrene resin (component A), 96 to 1 wt.% of polyolefin resin (component B) and 3 to 25 wt.% of one type and/or two or more types of polymer (however containing no components A and B) having a soluble parameter (SP) of 8.40 to 8, 70. Meanwhile, at least one layer of the other layer contains a polystyrene resin component. Thus, a cover can be easily manually released, its content can be taken out, and the content is not leaked in transporting or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container for packaging contents such as food. More specifically, the contents can be easily taken out by hand peeling off the lid film without leaking the contents, and the formability of the sheet for forming the container during vacuum and / or pressure forming is improved. The present invention relates to a container which can be molded efficiently in a short time, a container member comprising a lid, and an easily-openable container using the same.

[0002]

2. Description of the Related Art Containers used for food packaging and the like have their contents opened and taken out. However, in the case of a type in which the lid film is peeled off and opened, the adhesive strength of the sealing portion is high, and the film is difficult to peel off. You may find containers that require extra force or that cannot be opened successfully. These containers are also undesirable from a barrier-free point of view. However, if the adhesive strength is not sufficient, the contents may leak during transportation of the product. Accordingly, there has been a demand for an easily-openable container that can be easily peeled off by hand and the contents can be taken out, and the contents do not leak out during transportation or the like.

Polystyrene resins are widely used as injection molding materials and sheet molding materials because of their rigidity, good dimensional stability, and low cost. In addition, vacuum and / or air pressure moldability for forming a container shape is easier than that of a polyolefin resin, and since it is an amorphous resin, molding time, particularly cooling time, can be shortened, and molding dimensional stability is excellent. In addition, rigidity is high, which is preferable. However, polystyrene resins have the drawback that they are hard and brittle, and are inferior in oil resistance and chemical resistance to polyolefin resins.

On the other hand, polyolefin resins are excellent in oil resistance and chemical resistance to oils and organic solvents, and are excellent in strength. However, since it is a crystalline resin, there are disadvantages of low dimensional stability after molding and low rigidity.

[0005]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a sheet for forming a container which has excellent dimensional stability during vacuum pressure forming, and can be formed in a short time. A container with excellent impact resistance, rigidity, oil resistance, and chemical resistance, and when the contents are adhered to the lid to form a container, the contents do not leak out during transportation, but the lid film is easy to use. Another object of the present invention is to provide a container member comprising a container and a lid, from which the contents can be taken out by hand, and an easily openable container using the same.

[0006]

Means for Solving the Problems As a result of intensive study, the present inventors have found that a polystyrene-based resin and a polyolefin-based resin are blended or formed into a single-layer or multi-layer structure and are arranged at appropriate positions so that the container and the lid can be closed. Adjustment of the adhesive strength between
The present inventors have found that the above-mentioned problems such as impact resistance and rigidity can be solved, and have reached the present invention.

That is, the present invention includes the following inventions and embodiments.

(1) A container in which a multilayer sheet composed of two or more layers is formed, wherein at least one surface layer (a) of the multilayer sheet has the following (A), (B),
A container (I) comprising a resin composition containing the component (C), and at least one of the other layer portions contains the following component (D). (A) 1 to 96% by weight of polystyrene resin (B) 96 to 1% by weight of polyolefin resin (C) Solubility parameter (SP) is 8.40 to 8.70
3 to 25% by weight of one and / or two or more polymers (excluding the above (A) and (B)), (D) a polystyrene resin (2) The vessel (I) according to claim 1, And a lid (II) having the following surface layer (b). (II) At least one surface layer (b) of the single-layer film or the multilayer film composed of two or more layers contains a polyolefin resin, a polystyrene resin, or a blend of a polyolefin resin and a polystyrene resin. A lid for a container composed of a single-layer film or a multilayer film comprising two or more layers.

(3) In (I), (A) is 1 to 50% by weight of a polystyrene resin, (B) is 96 to 50% by weight of a polyolefin resin, and (II) is a single-layer film or two The container member according to (2), wherein at least one surface layer (b) of the multilayer film composed of the above layers is a polyolefin-based resin.

(4) (I) (A) is 96 to 50% by weight of a polystyrene resin, (B) is 50 to 1% by weight of a polyolefin resin, and (II) is a monolayer film or two The container member according to (2), wherein at least one surface layer (b) of the multilayer film composed of the above layers is a polystyrene resin.

(5) The container member according to any one of (2) to (4), wherein the polyolefin resin of (II) is polypropylene.

(6) The polymer as the component (C) is a copolymer of ethylene and at least one vinyl monomer of unsaturated carboxylic acid, unsaturated carboxylic acid ester or vinyl acetate, and at least one of styrene copolymers.
(1) The container according to (1).

(7) The polymer of the component (C) is at least one of an ethylene-methyl methacrylate copolymer and a styrene-butadiene copolymer (1).
The vessel described.

(8) The container according to (1), wherein the polymer of the component (C) is at least one of an ethylene-methyl methacrylate copolymer and a styrene-butadiene copolymer having a styrene content of 35 to 70% by weight. .

(9) The container according to (1), wherein the polymer of the component (C) is at least one of an ethylene-vinyl acetate copolymer and a styrene-butadiene copolymer.

(10) The container according to (1), wherein the polymer of the component (C) is at least one of an ethylene-vinyl acetate copolymer and a styrene-butadiene copolymer having a styrene content of 35 to 70% by weight. .

(11) The container member according to (2), wherein the container according to (6) to (10) is used.

(12) An easy-open container in which the container members (I) and (II) described in (2) or (11) are adhered at a surface layer (a) and a surface layer (b), respectively.

(13) The easy-open container according to (12), wherein (I) and (II) are bonded together by heat sealing at the surface layer portion (a) and the surface layer portion (b).

(14) The easily openable container according to (12) or (13), wherein the easily openable container is a food container.

(15) The easily-openable container according to (14), which is a tofu container.

(16) A method for packaging food using the container member according to (2) or (11), wherein the container is filled with the food and then a lid is adhered.

(17) The food package obtained in (16).

Hereinafter, the present invention will be described in detail.

The "container" as used in the present invention is composed of a "container" part for containing contents such as food and a "lid" part for preventing the contents from leaking out.

As the polystyrene resin (A) used in the present invention, so-called general-purpose polystyrene resins, rubber-modified polystyrene resins and mixtures thereof can be used. From the viewpoint of impact strength, a rubber-modified polystyrene resin is preferable. It does not include crystalline syndiotactic polystyrene recently marketed.

Here, the general-purpose polystyrene resin is G
PPS (General Purpose Polys)
(styrene), which is usually a styrene homopolymer. The rubber-modified polystyrene-based resin is obtained by polymerizing a styrene-based monomer in the presence of a rubber-like polymer, and is made of impact-resistant polystyrene (HIPS = h
This is also referred to as "high impact polystyrene". Further, as the molecular structure of the polystyrene resin, any of a linear structure and a branched structure may be used.

Styrene is generally used as a styrene monomer used in the production of a styrene resin.
Alkyl-substituted styrenes such as α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene and mixtures thereof can also be used.

The polyolefin resin as the component (B) used in the present invention includes an olefin homopolymer, an olefin copolymer copolymerized using copolymerizable olefins, or a mixture thereof. And olefins and copolymers other than olefins are not included.

Examples of these specific polyolefin resins include polyethylene, ethylene-butene-1
Copolymers of ethylene and α-olefins having 3 to 10 carbon atoms, such as copolymers, ethylene-hexene-1 copolymers, ethylene-4-methylpentene-1 copolymers, and polypropylene and propylene-ethylene block copolymers. Polymers, propylene-based polymers such as propylene-ethylene random copolymer and the like can be used.

Among these, polyethylene, ethylene-
Copolymer of ethylene and α-olefin having 4 to 10 carbon atoms, such as butene-1 copolymer and ethylene-hexene-1 copolymer, polypropylene, propylene-ethylene block copolymer, and propylene-ethylene random copolymer Coalescence is preferred.

The solubility parameter (SP) of the component (C) of the present invention is 8.40 to 8.70, preferably 8.4.
If it is 0 to 8.65, and less than 8.40 or more than 8.70, the impact resistance and elongation at break of the container, and the adhesive strength between the lid and the container are inferior.

Here, the solubility parameter is defined as Hil
It defines the attractive force between molecules according to the debrand-Scatchard theory. A detailed explanation is given in a general textbook of polymer science, for example, "Polymer Blend, Saburo Akiyama et al., CMC Co., Ltd., 4th printing, 12
5 to 144 (1991). However, the solubility parameter includes a method obtained by experiments such as a viscosity method and a degree of swelling method and a method obtained by calculation from a molecular structure. Therefore, in the present invention, a method of calculating from the molecular structure proposed by Small was used.This method and theory are described in "Journal of Applied Chemistry (Jour).
nal of Applied Chemistr
y), Volume 3, pages 71 to 80 (1953) ", whereby the solubility parameter was calculated using the following equation (Equation 1).

[0034]

(Equation 1) Fi represents the molar attraction force of a constituent group such as an atom or atomic group constituting the molecule, a bond type, V represents the molar volume, and ρ represents the density. M indicates a molecular weight, and in the case of a polymer, indicates a molecular weight of a monomer unit. As the value of Fi, the value of Small described in the above two documents was used. Ρ of the copolymer,
Σ Regarding Fi or M, assuming that additivity is satisfied, ρ, 単 独 of each homopolymer of the monomer units constituting the copolymer
The sum of the values of Fi or M multiplied by the mole fraction of the monomer unit was calculated and used.

As the polymer having a solubility parameter (SP) of the component (C) of 8.40 to 8.70 used in the present invention, one of unsaturated carboxylic acid, unsaturated carboxylic acid ester and vinyl acetate can be used. Copolymers composed of the above vinyl monomer and ethylene, styrene copolymers and the like are mentioned. Examples include ethylene-unsaturated carboxylic acid copolymers, ethylene-unsaturated carboxylic acid ester copolymers, ethylene-vinyl acetate copolymers, ethylene-unsaturated carboxylic acid ester-vinyl acetate terpolymers, ethylene and two or more unsaturated Examples include a multi-component copolymer composed of a carboxylic acid ester, a styrene-butadiene copolymer, a styrene-isoprene copolymer, a hydrogenated product of a styrene-butadiene copolymer, and a hydrogenated product of a styrene-isoprene copolymer.

Specific examples of the unsaturated carboxylic acid include acrylic acid and methacrylic acid. Specific examples of the unsaturated carboxylic acid ester include ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate,
Examples thereof include 2-ethylhexyl methacrylate, stearyl methacrylate, and glycidyl methacrylate.

Preferred examples of the copolymer comprising ethylene and at least one vinyl monomer selected from the group consisting of unsaturated carboxylic acids, unsaturated carboxylic esters and vinyl acetate used in the present invention include ethylene-acrylic acid copolymer and ethylene-methacrylic acid. Copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, And ethylene-vinyl acetate-glycidyl methacrylate copolymer.

The proportion of the vinyl monomer and ethylene in the copolymer is determined by a solubility parameter (SP) of 8.40 to
It can be determined appropriately within a range that gives a copolymer of 8.70, preferably 8.40 to 8.65. The ratio of the vinyl monomer in the copolymer of the vinyl monomer is 5 to 5.
It is preferably 60% by weight, more preferably 10 to 50% by weight. Further, there is no particular limitation on the bonding mode (for example, random, block, or alternating) between the vinyl monomer and ethylene in the copolymer. The melt flow rate of the copolymer is not particularly limited (according to JIS K7210, at a temperature of 190 ° C. and a load of 2.16 kgf), but is preferably about 1 to 500 g / 10 minutes.

Specific examples of the styrene copolymer used as the component (c) include styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-butadiene copolymer, hydrogenated styrene-isoprene copolymer, and the like. No.

Styrene monomers used in the production of component (c) include styrene, α-methylstyrene, o-
Alkyl-substituted styrenes such as methylstyrene, m-methylstyrene, p-methylstyrene, and mixtures thereof can also be used.

The proportion of the styrene monomer and its comonomer in the styrenic copolymer is determined by the solubility parameter (S
P) It can be determined appropriately within a range that gives a polymer of 8.40 to 8.70. The proportion of the comonomer in the styrenic copolymer is preferably from 20 to 80% by weight. More preferably, the content is 35 to 70% by weight. Further, there is no limitation on the bonding mode (for example, random, block, alternate) of the styrenic monomer and comonomer in the copolymer.

The polymer (C) having a solubility parameter (SP) of 8.40 to 8.70 in the present invention does not include the polystyrene resin (A) and the polyolefin resin (B) described above.

In the present invention, the proportion of the components (A) to (C) used is (A) 1 to 96% by weight of the polystyrene resin.
When the layer (b) of the lid is a polyolefin resin, it is preferably 1 to 50% by weight, more preferably 30 to 50% by weight.
% By weight. When the layer (b) of the lid is a polystyrene resin, it is preferably 96 to 50% by weight, more preferably 70 to 50% by weight.
５０50% by weight. The content of the polyolefin resin (B) is 96 to 1% by weight, and when the layer (b) of the lid is a polyolefin resin, the content is preferably 96 to 50% by weight, more preferably 70 to 50% by weight. In addition, (b) of the lid
When the layer is a polystyrene resin, it is preferably 1 to 50% by weight, more preferably 30 to 50% by weight. (C)
A polymer having a solubility parameter (SP) of 8.40 to 8.70 is 3 to 25% by weight, preferably 3 to 10% by weight. However, the total of the components (A) to (C) is 100% by weight.
It is. The present invention, unless otherwise impaired the present invention, (A) ~
In addition to (C), components other than these components may be added. In this case, the total including them is 100% by weight.

The adhesive strength with the lid can be freely controlled by the composition ratio of the polyolefin resin and the polystyrene resin.

(A) If the amount of polystyrene resin is too small, the rigidity is insufficient, while if it is too large, the oil resistance and chemical resistance are poor. (B) If the amount of the polyolefin resin is too small, the oil resistance and chemical resistance are poor, while if it is too large, the rigidity is insufficient. (C) solubility parameter (SP) is 8.40-8.
If the polymer is too small, the compatibility between (A) and (B) is low, and the impact resistance, elongation at break at break, and the adhesive strength between the lid and the container are poor, while if too large, the rigidity is poor. Become. When the layer (b) of the lid is a polystyrene resin or a composition ratio of 50% or more, if (A) is too small, the adhesive strength between the lid and the container is poor. When the layer (b) of the lid is a polyolefin resin or the composition ratio is 50% or more, (B)
If the value is too small, the adhesive strength between the lid and the container is poor.

At least one of the other layer portions of the surface layer portion (a) of the container of the present invention contains (D) a polystyrene resin. Further, a sheet composed of multiple layers of the present invention and other recycled materials may be mixed in this layer. As the polystyrene resin (D) used in the present invention, a so-called general-purpose polystyrene resin, a rubber-modified polystyrene resin, and a mixture thereof can be used. From the viewpoint of impact strength, a rubber-modified polystyrene resin is preferable.

Here, the general-purpose polystyrene resin is G
It is also called PPS and does not contain a soft component such as a rubber-like polymer. The rubber-modified polystyrene-based resin is obtained by polymerizing a styrene-based monomer in the presence of a rubber-like polymer.
S). Further, as the molecular structure of the polystyrene resin, any of a linear structure and a branched structure may be used. The branched type can be obtained by copolymerization with a polyfunctional vinyl monomer such as divinylbenzene, or by using a polyfunctional initiator, a polyfunctional chain transfer agent, or the like.

If necessary, additives such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, flame retardants, antistatic agents and mineral oils can be used.

As the styrene monomer used for the production of the component (D), styrene is generally used, but α-
Alkyl-substituted styrenes such as methylstyrene, o-methylstyrene, m-methylstyrene and p-methylstyrene can also be used.

In order to obtain the surface layer portion (a) of the multilayer sheet comprising two or more layers of the vessel of the present invention, a predetermined amount of each component is dry-blended with a mixing device such as a Henschel mixer or a tumbler. Using a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, etc.
What is necessary is just to heat-knead sufficiently at a temperature of 60 to 260 ° C., and then to granulate. If necessary, additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a flame retardant, an antistatic agent, and a mineral oil can be used.

The single-layer film or the multilayer film comprising two or more layers of the lid according to the present invention has at least one surface layer (b) as a polyolefin resin, a polystyrene resin or a blend of a polyolefin resin and a polystyrene resin. It contains. The adhesive strength with the container can be freely controlled by the composition ratio of the polyolefin resin and the polystyrene resin.

The polyolefin resin referred to herein includes an olefin homopolymer, an olefin copolymer copolymerized using copolymerizable olefins, or a mixture thereof.

As these specific resins, for example,
Ethylene such as polyethylene, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, etc.
And a propylene-based polymer such as polypropylene, a propylene-ethylene block copolymer, and a propylene-ethylene random copolymer. Among them, polypropylene is preferable.

The general-purpose polystyrene resin referred to here is:
It is also called GPPS and does not contain a soft component such as a rubber-like polymer. The rubber-modified polystyrene resin is obtained by polymerizing a styrene monomer in the presence of a rubber-like polymer, and is made of high-impact polystyrene (HI
PS). Further, as the molecular structure of the polystyrene resin, any of a linear structure and a branched structure may be used. The branched type can be obtained by copolymerization with a polyfunctional vinyl monomer such as divinylbenzene, or by using a polyfunctional initiator, a polyfunctional chain transfer agent, or the like.

In order to obtain the container of the present invention, a multilayer sheet composed of two or more layers is prepared, and then vacuum- and / or pressure-formed into a container shape, or a single-layer film or two or more layers. Are made, and these are adhered by the surface layer (a) and the surface layer (b).

As a method for obtaining a multilayer sheet comprising two or more layers according to the present invention, for example, a coextrusion molding method using a multilayer sheet extruder having two or more cylinders, or a similar apparatus can be used. Known methods and techniques such as a lamination molding method such as a dry lamination method, a wet lamination method, a sand lamination method, and a hot melt lamination method using a multilayer or single-layer film or sheet.

As a method for vacuum-pressure forming a multilayer sheet comprising two or more layers according to the present invention into a container shape, the sheet is heated using a commonly used vacuum and / or pressure forming machine. Known techniques such as a method of pressing against a mold, evacuating and / or evacuating, and then cooling by blowing air for several seconds. Then, if necessary, unnecessary portions are removed by punching with a punching blade.

The method for obtaining a single-layer film or a multilayer film comprising two or more layers according to the present invention includes, for example,
Single-layer extrusion or co-extrusion using a blown film manufacturing device or T-die film manufacturing device with one or more cylinders, or a single-layer or multilayer film obtained by a similar device Known techniques such as lamination molding methods such as dry lamination, wet lamination, sand lamination, and hot melt lamination.

For food packaging, a gas barrier resin layer such as nylon, polyvinyl alcohol, or high nitrile resin is preferably used as the intermediate layer of the multilayer film.

With the combination of the container member of the present invention comprising a container and a lid, an easily-openable container which can be easily opened by adhesion can be obtained. The most preferable method for bonding the two is a heat sealing method, but is not limited thereto. For example, a method for bonding with a hot melt adhesive is also adopted. As a method of heat sealing, a method of heating a vessel and a lid of a sealing portion, applying pressure, and sandwiching for several seconds is generally well known.

The container comprising the "vessel" and the "lid" obtained in the present invention can be used as a container for packaging the contents such as food, etc., without leaking the contents and by peeling off the lid film by hand. The material can be easily taken out, and the sheet for forming the container has good formability during vacuum pressure forming, and can be efficiently formed in a short time. The container of the present invention is useful as an easy-open container, and the container has a relatively high rigidity, so that containers for holding relatively heavy objects, such as tofu, pudding, jelly, yogurt, and so on, which are sold in supermarkets and the like. It can be used very suitably as a packaging container for ice cream and the like.

[0062]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples.

Examples 1 to 14 and Comparative Examples 1 to 5 Melting and kneading of the components shown in Tables 1 and 2 at a temperature of 160 to 240 ° C. using a two-layer three-layer extruder (both outer layers having the same material). Then, it was extruded from a T-die and processed into a sheet having a thickness of 0.5 mm. The obtained multilayer sheet was formed into a container shape of a tofu container using a vacuum pressure forming machine. The molded article was heat-sealed with a nylon / polypropylene two-layer film having a thickness of about 50 μm with the polypropylene layer as the sheet side, and then the adhesive strength was measured. The results are shown in Tables 1 and 2.

The data shown in Examples and Comparative Examples in Tables 1 and 2 were prepared or measured based on the following methods. All measurements were performed at 23 ° C. (1) Multilayer sheet processing Two types of three-layer extruders with cylinder diameters of 120 mmφ and 90 mmφ were used. The resin in the intermediate layer was extruded using a 120 mmφ extruder, and the resin in both outer layers was extruded using a 90 mmφ extruder. The extrusion amount was 1 for both outer layers.
This was performed so that the content of the intermediate layer was 5 wt% and the content of the intermediate layer was 70 wt%. (2) Tensile strength, elongation at break Using a multilayer sheet, the test was performed in accordance with ASTM D638. The tensile speed was 200 mm using the first test piece.
/ Min. The tensile strength was defined as the strength at break when the test piece was broken. (3) Surface Impact Strength (Impact Resistance) This was performed using a multilayer sheet in accordance with ASTM D3763. 7.5kg load from 80cm height by using "drop weight type graphic impact tester" of Toyo Seiki Seisakusho
Was naturally dropped onto the plane of the test piece, and the test piece was completely destroyed or penetrated by a striker provided below the weight. At this time, the total energy value of destruction was determined. (4) Vacuum forming Using a multi-layer sheet, a 54-piece (9 × 6) vacuum forming mold was used to heat at a heater temperature of 300 ° C. to perform vacuum forming into a tofu shape. One molded product is 78m long
m, width 110 mm, depth 43 mm, flange width 8 mm. The cooling time was varied depending on the sample, and was sufficiently performed so that deformation of the molded product did not occur. The cooling time was recorded. (5) Oil resistance Salad oil is applied to a container obtained by vacuum forming with respect to the container volume.
0% by volume was added and left at 40 ° C. for 24 hours. If oil did not leak, it was evaluated as ○, and if it leaked, it was evaluated as ×. (6) Heat Sealing A nylon / polypropylene two-layer film having a thickness of about 50 μm was heat-sealed using the polypropylene layer as a sheet side as a lid material. The conditions are 200 ° C., 3 seconds, pressure 2.
The test was performed at 5 kg / cm ² . (7) Adhesive strength The strength at 180 ° peeling (angle between lid and container) was measured at a pulling speed of 200 mm / min. The adhesive strength was represented by the strength with respect to the seal width. The peeled state was evaluated as “O” when the lid and the container were peeled off cleanly and showed an adhesive strength of 60 g / mm or more, and as “X” when the film was too strong or easily peeled off.

[0065]

[Table 1]

[0066]

[Table 2] * 1 (A) component A1: polystyrene resin (Nippon Polystyrene Co., Ltd. H
IPS, trade name Nippon Polystyrene H640, MFR =
2.8 g / 10 min, density 1.05 g / cm ³ , average gel particle size 2.2 μm, MFR measurement conditions: 200 ° C., load 5
kgf) A2: Polystyrene resin (H made by Nippon Polystyrene Co., Ltd.)
IPS, trade name Nippon Polystyrene H655, MFR =
2.7 g / 10 min, density 1.04 g / cm ³ , average gel particle diameter 0.2 μm, MFR measurement conditions: 200 ° C., load 5
kgf) * 2 (B) component B1: polypropylene (Sumitomo Chemical Industries, Ltd. trade name: Sumitomo Noblen AD571, MFR = 0.5 g / 10)
Min, density 0.90 g / cm ³ , MFR measurement condition: 230
° C, load 2.16 kgf) B2: Polypropylene (trade name: E401ETX, manufactured by Nippon Polychem Co., Ltd., MFR = 2.5 g / 10 min, density: 0.
90 g / cm ³ , MFR measurement conditions: 230 ° C., load 2.
* 3 (C) component: solubility parameter of component (C) (S
Table 3 shows the results calculated in the above (Equation 1) as P).

C1: Ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: ACLIFT C)
M5019, methyl methacrylate content 30% by weight, M
FR = 20 g / 10 min, MFR measurement conditions: 190 ° C., load 2.16 kgf) C2: ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Acrif WM403, methyl methacrylate content 38% by weight, MFR = 15 g) /
10 minutes, MFR measurement conditions: 190 ° C, load 2.16 kg
f) C3: styrene-butadiene copolymer (JSR Corporation)
C4: styrene-butadiene block copolymer (JS, TR2250, styrene content 50%, butadiene content 50%)
R2400, TR2400, styrene content 60%, butadiene content 40%) C5: styrene-butadiene block copolymer (JS
R6, TR2000, styrene content 40%, butadiene content 60%) C6: Hydrogenated styrene-isoprene block copolymer (Kuraray Co., Ltd., trade name Septon 2104, styrene content 65%, isoprene content 35%) C7: ethylene-vinyl acetate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumitate RB-11, vinyl acetate content 41% by weight, MFR = 60 g / 10 minutes, MFR measurement conditions: 190 ° C., load 2.16 kgf) C8 : Polymethyl methacrylate (Sumitomo Chemical Co., Ltd.)
Made, trade name SUMIPEX-BMHG, MFR = 0.5g
/ 10 min, MFR measurement conditions: according to ASTM D 1238) * 4 (D) component D1: polystyrene resin (H made by Nippon Polystyrene Co., Ltd.)
IPS, trade name Nippon Polystyrene H640, MFR =
2.8 g / 10 min, density 1.05 g / cm ³ , average gel particle size 2.2 μm, MFR measurement conditions: 200 ° C., load 5
kgf) D2: polypropylene (trade name, manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen AD571, MFR = 0.5 g / 10)
Min, density 0.90 g / cm ³ , MFR measurement condition: 230
° C, load 2.16 kgf) * 5 (E) component E1: polystyrene resin (H made by Nippon Polystyrene Co., Ltd.)
IPS, trade name Nippon Polystyrene H640, MFR =
2.8 g / 10 min, density 1.05 g / cm ³ , average gel particle size 2.2 μm, MFR measurement conditions: 200 ° C., load 5
kgf) E2: Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumitomo Noblen AD571, MRF = 0.5 g / 10)
Min, density 0.90 g / cm ³ , MFR measurement condition: 230
° C, load 2.16 kgf) * 6 It was too sticky and could not be peeled off.

[0068]

[Table 3] The following can be seen from the results. All the examples satisfying the conditions of the present invention have excellent dimensional stability during vacuum and / or pressure forming of a sheet for forming a container, can be formed in a short time, and have impact resistance, rigidity and oil resistance. The container was excellent in chemical resistance, had sufficient adhesive strength as a container, and was easily openable so that the contents could be easily taken out by peeling off the lid film by hand. on the other hand,
Comparative Example 1 in which the vessel was a single-layer polystyrene resin was inferior in oil resistance and adhesive strength. Similarly, Comparative Example 2 in which the container had a single layer of polypropylene required a long cooling time during vacuum forming, and the adhesive strength with the film of the lid was too strong to peel off well. Comparative Example 3 containing no component (C) is inferior in tensile elongation, impact resistance, and adhesiveness. Comparative Examples 4 and 5 containing a polymer having a solubility parameter (SP) outside the specified range as component (C) are inferior in tensile elongation at break, impact resistance, and adhesion.

Continued on front page (72) Inventor Takahiro Ishii 1-6-6 Takasago, Takaishi-shi, Osaka Japan Polystyrene Co., Ltd. (72) Inventor Masaru Sato 1-6-6 Takasago, Takaishi-shi, Osaka Japan Polystyrene Styrene (72 ) Inventor Akio Uemura 1-6 Takasago, Takaishi City, Osaka Prefecture, Japan Polystyrene Co., Ltd. (72) Inventor Masato Takaku 1-6-6 Takasago, Takaishi City, Osaka Japan Polystyrene Co., Ltd.

Claims (17)

[Claims] 1. A container formed by molding a multilayer sheet comprising two or more layers, wherein at least one surface layer (a) of the multilayer sheet has the following components (A), (B) and (C) (I) comprising a resin composition containing: (A) wherein at least one of the other layers contains the following component (D): (A) 1 to 96% by weight of polystyrene resin (B) 96 to 1% by weight of polyolefin resin (C) Solubility parameter (SP) is 8.40 to 8.70
3 to 25% by weight of one and / or two or more polymers (excluding the above (A) and (B)) 2. A container member comprising the container (I) according to claim 1 and a lid (II) having the following surface portion (b). (II) At least one surface layer (b) of the single-layer film or the multilayer film composed of two or more layers contains a polyolefin resin, a polystyrene resin, or a blend of a polyolefin resin and a polystyrene resin. A lid for a container composed of a single-layer film or a multilayer film comprising two or more layers. (I) (A) is 1 to 50% by weight of a polystyrene resin, and (B) is 96% of a polyolefin resin.
3 to 50% by weight, wherein (II) is a single-layer film or a multilayer film composed of two or more layers, and at least one surface layer portion (b) is a polyolefin resin.
The container member as described in the above. (I) (A) is 96 to 50% by weight of a polystyrene resin, and (B) is 5% of a polyolefin resin.
The container member according to claim 2, wherein the content is 0 to 1% by weight, and (II) is a single-layer film or a multilayer film including two or more layers, and at least one surface layer (b) is a polystyrene resin. 5. The container member according to claim 2, wherein the polyolefin resin (II) is polypropylene. 6. The polymer of component (C) is at least one of a copolymer of ethylene and at least one vinyl monomer of unsaturated carboxylic acid, unsaturated carboxylic acid ester or vinyl acetate, and a styrene copolymer. The vessel of claim 1. 7. The vessel according to claim 1, wherein the polymer of the component (C) is at least one of an ethylene-methyl methacrylate copolymer and a styrene-butadiene copolymer. 8. The vessel according to claim 1, wherein the polymer of the component (C) is at least one of an ethylene-methyl methacrylate copolymer and a styrene-butadiene copolymer having a styrene content of 35 to 70% by weight. 9. The container according to claim 1, wherein the polymer of the component (C) is at least one of an ethylene-vinyl acetate copolymer and a styrene-butadiene copolymer. 10. The polymer of component (C) is ethylene-
Vinyl acetate copolymer, styrene content of 35% by weight to 7%
The vessel of claim 1 which is at least one of 0% by weight styrene-butadiene copolymer. 11. The container member according to claim 2, wherein the container according to claim 6 is used. 12. An easily openable container wherein the container members (I) and (II) according to claim 2 or 11 are adhered at a surface layer (a) and a surface layer (b), respectively. 13. The easy-open container according to claim 12, wherein (I) and (II) are bonded by heat sealing at the surface layer (a) and the surface layer (b), respectively. 14. The easily-openable container according to claim 12, wherein the easily-openable container is a food container. 15. The easily-openable container according to claim 14, which is a tofu container. 16. A method for packaging food using the container member according to claim 2 or 11, wherein the container is filled with the food and then a lid is adhered. 17. The food package obtained in claim 16.