KR20040055651A - Multilayer structure and package - Google Patents

Abstract

PURPOSE: A polystyrene based multilayer structured material and a package using the same are provided to have a good oil resistance, heat sealability and reusability. CONSTITUTION: The multilayer structure(10) comprises a surface layer(1) of a polyolefin based resin; an intermediate layer(2); and a substrate layer(3) of a polystyrene based resin. The intermediate layer comprises 25 to 75 wt.% of a polystyrene based resin, 75 to 25 wt.% of a polyolefin based resin and 1 to 20 parts by weight of a compatibilizer composed of a block copolymer based on the 100 parts by total weight of the polystyrene based resin and the polyolefin based resin. The block copolymer is a block copolymer of an aromatic vinyl and a conjugated diene.

Description

MULTILAYER STRUCTURE AND PACKAGE}

The present invention relates to a multilayer structure mainly composed of a polystyrene resin and its use. In particular, the present invention relates to a polystyrene-based resin multilayer structure suitable for a package such as a container, a cover, a packaging material of a food or a medicine, and a package using the same.

Polystyrene resin sheets are widely used as packaging materials for food containers due to their thermoforming and rigidity. Also, as a cover material for a container molded from the resin sheet, a molded cover molded to reduce residual oxygen in the container was used.

Since most foods and medicines are packaged after heat sterilization and disinfection, there is no problem even with a packaging material of polystyrene resin.

Recently, however, safety of foods and pharmaceuticals is highly demanded, such as incorporation of foreign substances into foods, food poisoning by O-157, and hospital infections. The packaging material of polystyrene-based resin is required to be improved in view of oil resistance, chemical resistance, and heat resistance when heat sterilization, disinfection after packaging or packaging at high temperature. In addition, in recent years, with the spread of microwave ovens, a form of heating food while being put in a packaging material has been proposed, and improvement of heat resistance and oil resistance of the packaging material has been highlighted.

In addition, when heat-sealing a tight cover from the outside, if the melting | fusing point of resin of a heating side and a fusion | melting side is the same, a heating side will melt | dissolve at the fusion | melting possible temperature, and it will become an appearance defect. In addition, although it has been examined to use both a resin having a melting point lower than that of the resin on the heating side to achieve a good sealing property and appearance, the resin having a low melting point is difficult to handle due to its low rigidity and lack of rigidity as a molding cover. .

In general, polystyrene resin sheets have excellent rigidity and thermal formability, but are inferior in oil resistance, chemical resistance, and heat resistance, so that they cannot be heat sealed with polyolefin containers. There is a need for the development of a thermoformed, tightly fitted cover sheet.

On the other hand, the polyolefin resin sheet is excellent in oil resistance, chemical resistance and heat resistance, but is far short of the polystyrene resin sheet in terms of thermoformability and rigidity.

As a method of utilizing the thermoformability and rigidity of the polystyrene resin sheet and improving oil resistance, heat resistance, and heat sealing property, studies have been conducted to blend or commercialize polyolefins in polystyrene. However, if polystyrene is present on the surface in contact with the contents, there is a problem of a decrease in strength due to the penetration of oil or a problem of transition of the residual monomers to the contents (for example, Japanese Patent Laid-Open No. 1998-119199, Japanese Patent Laid-Open No. 1994). -190988, Japanese Patent Laid-Open No. 1999-235793, Japanese Patent Laid-Open No. 2000-52505, and Japanese Patent Laid-Open No. 2000-26679). In addition, since the melting point of the resin on the heating side and the fusion side is not different simply by blending or commercializing, the heat-sealed portion melts when heat-sealed at a fusionable temperature, and the problem of poor appearance cannot be solved.

As another method, a method of laminating polyolefins by co-extrusion has also been studied in order to have oil resistance, heat resistance, or to provide a melting point difference between the resin on the heating side and the resin on the fusion side. As a technique for bonding polystyrene and polyolefin, there is a method using an adhesive layer such as an ethylene-vinyl acetate copolymer (EVA) -based adhesive resin, a styrene-butadiene-based copolymer, a styrene-isoprene-based copolymer, or the like. However, since the components of the adhesive layer deteriorate due to deterioration in performance due to mixing of different materials and thermal history due to recycling due to recycling during sheet manufacturing, which is generally performed, it is difficult to be practical such as poor appearance due to gelation (for example, , Japanese Unexamined Patent Publication No. 1983-197049).

On the other hand, there is also a method of adhering a polypropylene film, but since direct polypropylene and polystyrene cannot be thermally bonded, an adhesive resin or an adhesive is required. However, the ethylene-vinyl acetate copolymer composition used as the adhesive resin or the adhesive is preferably higher in vinyl acetate content in order to obtain sufficient interlayer strength, but there is a problem such as gelation at the time of recycling. When the content was lowered, there was a problem that the interlayer strength was insufficient. There is also a method of using an ethylene-based multi-component copolymer or a graft modified polyolefin polymer as an adhesive resin, but it is expensive and not practical (see, for example, Japanese Unexamined Patent Publication No. 1997-290492).

The present invention has been made in view of the above problems, and an object thereof is to provide a polystyrene-based multilayer structure and a package excellent in oil resistance, heat sealability and recyclability.

1 is a cross-sectional view showing a first multilayer structure of the present invention.

2 shows a container and a cover made of the first multilayer structure of the present invention, (a) is a cross sectional view of the cover, and (b) is a sectional view of the container.

3 is a cross-sectional view showing a second multilayer structure of the present invention.

4 shows a container and a cover made of the second multilayer structure of the present invention, (a) is a cross sectional view of the cover, and (b) is a sectional view of the container.

Explanation of reference numerals

1: surface layer

2: middle layer

3: substrate layer

4: substrate layer for recovery (base layer)

5, 6: flange

7: first surface layer

8a, 8b: adhesive layer

9: second surface layer

10, 11, 12: multilayer structure

20, 21: container

30, 31: cover

As a result of intensive studies, the present inventors have found that the polyolefin-based resin layer is formed on the polystyrene-based resin layer through an intermediate layer or an adhesive layer made of polystyrene-based resin, polyolefin-based resin and a compatibilizer instead of the adhesive resin or adhesive. It was found that a multilayer structure was obtained and completed the present invention.

According to the present invention, there are provided the following multilayer structures and containers, covers and packages formed from the multilayer structures.

[1] 25 to 75% by weight of polystyrene resin, 75 to 25% by weight polyolefin resin, and 30 to 80% by weight of aromatic vinyl in a base layer made of polystyrene resin, and a double bond based on conjugated diene. Intermediate layer containing 1 to 20 parts by weight of a compatibilizer composed of a block copolymer of aromatic vinyl and conjugated diene saturated with hydrogen of not less than% (which is based on 100 parts by weight of the polystyrene-based resin and the polyolefin-based resin) Through, the multilayer structure with a surface layer which consists of polyolefin resin.

[2] A base layer comprising polystyrene resin and polyolefin resin, having 25 to 75% by weight of polystyrene resin, 75 to 25% by weight polyolefin resin, and 30 to 80% by weight of bonded aromatic vinyl, based on conjugated diene. A multilayer structure in which a surface layer made of a polyolefin resin is formed through an intermediate layer composed of a compatibilizer composed of a block copolymer of an aromatic vinyl and a conjugated diene saturated with at least 35% hydrogen by double bonds.

[3] A multilayer structure in which a first surface layer made of polyethylene resin and a second surface layer made of polypropylene resin are formed on a base layer made of polystyrene resin through an adhesive layer made of polystyrene resin, polypropylene resin and compatibilizer. .

[4] a first surface layer made of polyethylene resin, a polystyrene resin, polypropylene resin, and a compatibilizer, through an adhesive layer made of polystyrene resin, polypropylene resin, and a compatibilizer on a base layer made of polystyrene resin A multilayer structure having a second surface layer formed.

[5] a double bond based on conjugated diene, having 25 to 75% by weight of polystyrene resin, 75 to 25% by weight polypropylene resin, and 30 to 80% by weight of bonded aromatic vinyl, on a base layer made of polystyrene resin. 1 to 20 parts by weight of a compatibilizer consisting of a block copolymer of aromatic vinyl and conjugated diene saturated with at least 35% hydrogen, which is based on 100 parts by weight of the polystyrene resin and the polypropylene resin. The multilayer structure as described in [3] in which the 1st surface layer which consists of polyethylene-type resin, and the 2nd surface layer which consists of polypropylene resin are formed through one adhesive layer.

[6] a double layer based on conjugated diene, containing 25 to 75% by weight of polystyrene resin, 75 to 25% by weight polypropylene resin, and 30 to 80% by weight of bonded aromatic vinyl in a substrate layer made of polystyrene resin. 1 to 20 parts by weight of a compatibilizer consisting of a block copolymer of aromatic vinyl and conjugated diene saturated with hydrogen by 35% or more of the bond (to 100 parts by weight of the polystyrene-based resin and the polypropylene-based resin combined) Through the blended adhesive layer, the first surface layer made of polyethylene-based resin, and 25 to 75% by weight of polystyrene-based resin, 75 to 25% by weight of polypropylene-based resin, and 30 to 80% by weight of bonded aromatic vinyl are contained in conjugated diene. 1 to 20 parts by weight of a compatibilizer consisting of a block copolymer of aromatic vinyl and conjugated diene saturated with at least 35% hydrogen based double bonds (which The multilayer structure as described in [4] in which the 2nd surface layer which mix | blended the said polystyrene resin and the said polypropylene resin with respect to 100 weight part combined) was formed.

[7] The multilayer structure according to any one of [3] to [6], wherein the compatibilizer of the adhesive layer and / or the second surface layer is a hydrogenated product of a block copolymer of aromatic vinyl and conjugated diene.

[8] The multilayer structure according to [1] or [2], wherein the polyolefin resin of the surface layer is a polypropylene resin.

[9] The multilayer structure according to any one of [1] to [8], wherein the glass transition temperature of the compatibilizer is -60 ° C or lower.

[10] A container, cover, or package formed from the multilayer structure according to any one of [1], [2], [8], or [9], wherein the surface layer faces the contents.

[11] A container, cover, or package formed from the multilayer structure according to any one of [3] to [7] and [9], wherein the first surface layer faces the contents.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

[First multilayer structure]

The first multilayer structure of the present invention is formed of a base layer, an intermediate layer and a surface layer.

As a polystyrene resin used for a base material layer, For example, homopolymers or copolymers, such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, paramethyl styrene, chloro styrene, bromostyrene, vinyl xylene, styrene-anhydride Maleic acid copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer and the like. Furthermore, impact polystyrene which mixed or graft-polymerized rubber, such as butadiene rubber, styrene butadiene rubber, and ethylene-propylene rubber, can be used for the styrene resin. Polystyrene and rubber modified impact resistant polystyrene are preferred, and rubber modified impact resistant polystyrene is more preferred.

In addition, 0.5-20 g / 10min is preferable and, as for the melt-flolate (MFR: JIS K 7210) of styrene resin, 1-10 g / 10min is more preferable.

Moreover, when a composition of polystyrene resin and polyolefin resin is used for a base material layer, weight reduction and heat resistance improve and it is preferable. At this time, a compatibilizer may be used to improve the compatibility of the two resins.

The composition preferably consists of 30 to 100% by weight of polystyrene resin, and 70 to 0% by weight of polyolefin resin. More preferably, it consists of 50 to 90 weight% of polystyrene resins, and 50 to 10 weight% of polyolefin resins. If the polystyrene-based resin is less than 30% by weight, the rigidity of the container is low and the characteristics of the polystyrene-based resin are not obtained.

The polyolefin resin used in the base material layer is not particularly limited as long as it is a resin obtained by homopolymerization or copolymerization of an α-olefin such as ethylene, propylene, 1-butene, isobutylene, 4-methyl-1-pentene and the like. The copolymer is preferably any of random copolymers and block copolymers. Olefin thermoplastic elastomers, such as 2 or 3 or more types of copolymer rubbers of an alpha olefin, or a copolymer of an alpha olefin and another monomer may be contained. Examples of these copolymer rubbers include ethylene-propylene copolymer rubber (EPR), ethylene-butene copolymer rubber (EBR), ethylene-propylene-diene copolymer rubber (EPDM), and the like. As polyolefin resin, high density polyethylene is preferable because it has high oil resistance and chemical resistance. Moreover, since polypropylene resin is high in heat resistance and can improve heat resistance in addition to oil resistance and chemical resistance, it is more preferable.

Melt florate (MFR: JIS K 7210) is preferably 0.1 to 60 g / 10 minutes, more preferably 0.3 to 20 g / 10 minutes.

The polyolefin resin used for the surface layer is not particularly limited as long as it is a resin obtained by homopolymerizing or copolymerizing α-olefins such as ethylene, propylene, 1-butene, isobutylene, 4-methyl-1-pentene and the like. The copolymer may be any of random copolymers and block copolymers. Among them, high density polyethylene is preferred because of its high oil resistance and chemical resistance. Moreover, since polypropylene resin is high in heat resistance and can improve heat resistance in addition to oil resistance and chemical resistance, it is more preferable.

Melt florate (MFR: JIS K 7210) is preferably 0.1 to 60 g / 10 minutes, more preferably 0.3 to 20 g / 10 minutes.

The intermediate layer existing between the base layer and the surface layer consists of a polystyrene resin, a polyolefin resin and a compatibilizer.

Polystyrene resin or polyolefin resin used for an intermediate | middle layer is the same as polystyrene resin or polyolefin resin used for a base material layer and / or a surface layer. The polystyrene resin or polyolefin resin of the intermediate layer may be the same as or different from the polystyrene resin or polyolefin resin of the base layer and / or the surface layer.

The compounding quantity of an intermediate | middle layer is 25 to 75 weight% of polystyrene resin, Preferably it is 50 to 70 weight%, 75 to 25 weight% of polyolefin resin, Preferably it is 50 to 30 weight%. The compatibilizer is 1 to 20 parts by weight based on 100 parts by weight of the polystyrene resin and the polyolefin resin. Preferably it is 2-10 weight part. If the polystyrene-based resin is less than 25% by weight, the interlayer strength with the base layer is insufficient. If the polystyrene-based resin is more than 75% by weight, the interlayer strength with the surface layer is insufficient.

In order to improve the compatibility of the polystyrene resin and the polyolefin resin, a compatibilizer is added to the intermediate layer. As a compatibilizer, the block copolymer of aromatic vinyl, conjugated diene, ie, butadiene, isoprene is mentioned. The block copolymer is a bonded aromatic vinyl content of 30 to 80% by weight and exhibits rubber elasticity. For example, styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), and the like. Especially, since styrene-ethylene-butylene styrene copolymer (SEBS) which is a hydrogenated product of SBS and styrene-butadiene-butylene styrene copolymer (SBBS) which is a partial hydrogenated product of SBS do not have a double bond in a structural side chain, It is preferable because it is difficult to crosslink when receiving a history.

Since the compatibilizer is repeatedly subjected to thermal history during recycling, it is preferable to prevent the gelation from being hydrogenated.

Examples of such compatibilizers include partially hydrogenated block copolymers. The partially hydrogenated block copolymer has a polymer block (X) mainly composed of one or more aromatic vinyls and a polymer block (Y) mainly composed of one or more conjugated dienes.

The polymer block (X) mainly composed of aromatic vinyl is a polymer block having a weight ratio of aromatic vinyl and conjugated diene in a composition range of 100/0 to 60/40, preferably 100/0 to 80/20. When aromatic vinyl and conjugated diene copolymerize, the distribution of conjugated diene in this block is preferably random, taper (increase or decrease of monomer component depending on molecular chain), some block shape or any combination thereof. Do.

As an aromatic vinyl provided here, alkylstyrene, such as styrene, (alpha) -methylstyrene, p-methylstyrene, p-tertiary butyl styrene, paramethoxy styrene, vinyl naphthalene, 1, 1- diphenyl ethylene, divinylbenzene 1 type, or 2 or more types are chosen from these etc., and styrene is especially preferable.

The polymer block (Y) mainly composed of conjugated diene is a polymer block having a weight ratio of conjugated diene to aromatic vinyl in a composition range of 100/0 to 60/40, preferably 100/0 to 80/20. When conjugated diene and aromatic vinyl are copolymerized, the distribution of aromatic vinyl in this block may be any of random, tapered (the monomer component increases or decreases depending on the molecular chain), some block shape, or any combination thereof. desirable.

Examples of the conjugated diene provided herein include butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene, and the like. 1 type, or 2 or more types are selected from among, butadiene and / or isoprene are especially preferable.

The molecular structure of the block copolymer is preferably linear, branched, radial or a combination thereof, but is preferably linear. Among them, a structure having two or more Xs is preferable, for example, X-Y-X, X-Y-X-Y, Y-X-Y-X-Y structures are preferable, and X-Y-X structures are particularly preferable.

Each of the block (X) or the block (Y) may have the same structure or may have different structures such as monomer component content, distribution in their molecular chains, molecular weight of the block, and microstructure. For example, X at both ends may be X-Y-X 'having a different molecular weight.

The aromatic vinyl content of the partially hydrogenated block copolymer is 30 to 80% by weight, preferably 40 to 80% by weight, more preferably 45 to 75% by weight. If the aromatic vinyl content is less than 30% by weight, the affinity between the block copolymer and the styrene resin is insufficient, so that the block copolymer present at the interface between the styrene resin phase and the olefin resin phase becomes insufficient, resulting in no commercialization effect. On the other hand, if it exceeds 80% by weight, the affinity with the styrene-based resin becomes excessive and the block copolymer is incorporated into the styrene-based resin, so that the compatibilizer effect is also insufficient.

The amount of vinyl bonds in the conjugated diene block before hydrogenation of the partially hydrogenated block copolymer is 20 to 90% by weight, preferably 30 to 80% by weight, more preferably 40 to 75% by weight. Here, the amount of vinyl bonds in the conjugated diene block before hydrogenation is 1,2- among conjugated dienes combined in the form of 1,2-, 3,4- and 1,4-bonds in the block copolymer. Let it be ratio of what is combined by the bond and 3, 4- bond. If the amount of vinyl bonds in the conjugated diene block before hydrogenation is less than 20% by weight, the affinity between the block copolymer and the olefin resin is insufficient, and the compatibilization effect is insufficient. On the other hand, when it exceeds 90 weight%, since affinity with an olefin type becomes excessive and a block copolymer is incorporated in an olefin resin, a compatibility effect also becomes inadequate.

The partially hydrogenated block copolymer used in this invention saturates 35% or more of the double bond based on conjugated diene in the said block copolymer by hydrogenating the said block copolymer. If the hydrogenation rate is less than 35%, the affinity between the block copolymer and the olefin resin is lowered, so that the block copolymer is incorporated on the styrene resin and the commercialization effect is insufficient. In addition, the amount of remaining vinyl bonds in the partially hydrogenated block copolymer used in the present invention is preferably less than 10%, more preferably 5% or less, and still more preferably 3% or less. The amount of vinyl bonds remaining here is the amount of the vinyl structure remaining without hydrogenation with respect to the initial conjugated diene 100. If the amount of residual vinyl bonds in the block copolymer is 10% or more, the compatibilization effect is insufficient.

As for the weight average molecular weight of the polymer block (X) mainly having the aromatic vinyl of a partially hydrogenated block copolymer, 5000-70000 are preferable for the polymer block (Y) mainly having a conjugated diene. If the molecular weight of the polymer block (X) is less than 5000, the affinity with the styrene resin is lowered, and if the molecular weight of the polymer block (Y) is less than 5000, the affinity with the olefinic resin is lowered and the compatibility effect is inferior. In addition, when the molecular weight of the polymer block (X) exceeds 50000 or the molecular weight of the polymer block (Y) exceeds 70000, the molecular weight as the block copolymer becomes excessive, so that the melt viscosity increases and the styrene resin and the olefin resin Dispersion in the resin composition which consists of these becomes inadequate, and a commercialization effect falls.

The melt flow rate (MFR: JIS K 7210) of the partially hydrogenated block copolymer is preferably 0.1 to 50 g / 10 minutes, more preferably 0.5 to 30 g / 10 minutes, even more preferably 1 to 20 g / 10 minutes. . If the melt flow rate is less than 0.1 g / 10 min, the melt viscosity is too high and a sufficient compatibilization effect is not obtained. If the melt florate is more than 50 g / 10 min, the strength of the interface between the styrene resin and the olefin resin is lowered.

In addition, the use of partially hydrogenated styrene-butadiene-butylene styrene block copolymers has the effect of being able to be manufactured at low cost.

The lower the glass transition temperature of the compatibilizer, the better the low temperature impact resistance is preferred. The glass transition temperature is preferably -60 ° C or lower, more preferably -70 ° C or lower.

The thickness of the multilayer structure is not particularly limited, but is 0.1 to 2 mm, preferably 0.2 to 1.5 mm. The surface layer is 0.005 to 0.1 mm, preferably 0.01 to 0.1, and the interlayer intervening is 0.005 mm or more, preferably 0.01 mm or more, and the rest is the base layer.

If the total thickness is less than 0.1 mm, the film is cut at the time of forming the container, which becomes a problem in practical use. In addition, when it exceeds 2 mm, sheet winding is difficult and cannot be used for a roll container forming machine, which is not practical.

If the thickness of the surface layer is less than 0.005 mm, the film is cut at the time of forming the container, which becomes a problem in practical use. In addition, exceeding 0.1 mm causes a significant decrease in the thermoforming cycle and a decrease in rigidity.

If the thickness of the intermediate layer is less than 0.005 mm, the film is cut when the container is used, and the adhesive strength between the surface layer and the base layer is lowered and the contents cannot be protected.

Similarly, in the case of forming the cover by thermoforming, if the overall thickness is less than 0.1 mm, the film is cut at the time of forming the cover, which becomes a problem in practical use. In addition, if the thickness exceeds 2mm, the sheet is difficult to be wound, which is not practical because it cannot be used in a roll forming machine.

If the thickness of the surface layer is less than 0.005 mm, the film is cut at the time of forming the cover, which becomes a practical problem. Moreover, when it exceeds 0.1 mm, a thermoforming cycle will cause a remarkable fall and a rigid fall.

If the thickness of the intermediate layer is less than 0.005 mm, the film is cut in forming the cover, and the adhesive strength between the surface layer and the base layer is lowered and the contents cannot be protected.

In addition, the base layer, the intermediate layer, and the surface layer may be a lubricant, a softener, a plasticizer, an antioxidant, an antistatic agent, calcium carbonate, talc, magnesium phosphate, aluminum hydroxide, barium sulfate, calcium silicate, titanium oxide, It may also contain other components such as a release agent. Coloring is also possible.

The first multilayer structure of the present invention may further laminate other layers on the side opposite to the intermediate layer of the base layer. For example, resin layers such as ethylene-vinyl alcohol copolymers, polyvinylidene chloride, nylon, polyethylene terephthalate, aluminum deposition layers, aluminum foils, aluminum, etc., for the purpose of improving oxygen gas barrier properties and reducing deformation in the case of containers. A layer made of a material having excellent gas barrier properties such as iron, copper, and the like can be laminated. These layers may be a resin layer containing an inorganic filler or a composite material with a metal, paper, or the like.

The first multilayer structure of the present invention can be produced by coextrusion or lamination processing or the like. As the coextrusion molding method, for example, a polystyrene substrate layer, a surface layer, and an intermediate layer interposed therebetween are melt-extruded using different extruders, stacked in a feed block to form a film on a flat die, and a multilayer die in a die. A method of laminating and forming a film is mentioned. Extrusion laminate can be used as a lamination process. Usually, the co-extrusion lamination method which laminates the co-extruded two-layered structure which consists of an intermediate | middle layer of a polyolefin resin film, a polystyrene resin of a molten state, and a base material layer is used preferably.

Scrap generated during molding may be recovered in the substrate layer within a range of not impairing properties, or may be recovered by providing a new layer as part of the substrate layer.

The first multi-layered structure of the present invention has sufficient interlaminar strength and utilizes the thermoformability and rigidity of the polystyrene-based resin by laminating a surface layer on a base layer made of a polystyrene-based resin through an intermediate layer without using an adhesive resin and an adhesive. The oil resistance, chemical resistance, and heat resistance which polyolefin resin has can be provided.

Moreover, since the multilayer structure of this invention does not use adhesive resin or an adhesive agent, gelatinization at the time of recycling can be prevented.

[Container, Cover and Package Made of First Multilayer Structure]

The package of the present invention is formed from the sheet-like multilayer structure. As an example of a package, a container and / or a cover is mentioned, for example.

The package of the present invention is obtained by heating and melting the sheet-like multilayer structure into a desired shape, and is preferably obtained by ordinary vacuum forming, pressure forming, or the like. In addition, it can be obtained by molding by injection molding, injection blow molding, blow molding or the like using the above resin.

1A and 1B show cross-sectional views of the first multilayer structure of the present invention.

The multilayered structure 10 shown in FIG. 1A consists of a surface layer 1, an intermediate layer 2, and a base material layer 3. The multilayered structure 11 shown in FIG. 1B includes a surface layer 1, an intermediate layer 2, and a substrate. It consists of the layer 3 and the base material layer 4 for collection | recovery. The recovering base material layer 4 is a layer obtained by pulverizing a sheet-like multilayer structure in the same manner as the base material layer, and the base material layer of the present invention comprises the base material layer 3 and the recovering base material layer 4.

2 shows a cross-sectional view of a container and cover made of a first multilayer structure of the present invention.

The container 20 and the cover 30 shown in FIGS. 2A and 2B are manufactured from the multilayer structure 10 of FIG. 1A, and the surface layer 1 of the multilayer structure 10 is on the contents side. The multilayer structure 10 extends to form the flange portion 5.

In addition, although the shape of the flange part 5 of the container 20 is not specifically limited, Usually, it is circular, square, etc .. In addition, a container shape may be a cup shape or a tray shape.

The container and / or cover of the present invention is excellent as a package of food or medicine because of excellent oil resistance, chemical resistance and heat resistance. Specifically, it is used as a package of lunch boxes, tofu, and side dishes.

Moreover, since it hardly gels at the time of recycling, it is excellent in recyclability.

[2nd multilayer structure]

The second multilayer structure of the present invention is formed of a substrate layer, an adhesive layer, and first and second surface layers.

The same thing as the 1st multilayer structure mentioned above can be used for a base material layer.

The polyethylene-based resin used for the first surface layer may be particularly used as long as it is a homopolymer of ethylene or a resin obtained by copolymerizing ethylene with an α-olefin such as propylene, 1-butene, isobutylene, 4-methyl-1-pentene, and the like. It is not limited. The copolymer is preferably any of random copolymers and block copolymers.

The higher the surface layer in that at least one of polyethylene-based resin as the density of 900kg / m ³ or more is preferable, and more preferably has a density of 920kg / m ³ and chemical resistance and is excellent in terms of protection of the contents.

Melt florate (MFR: JIS K 7210) is preferably 0.1 to 60 g / 10 minutes, more preferably 0.3 to 20 g / 10 minutes.

The polypropylene resin used in the second surface layer may be a homopolymer of propylene or a resin obtained by copolymerizing propylene with an α-olefin such as ethylene, 1-butene, isobutylene, 4-methyl-1-pentene, or the like. It is not specifically limited. The copolymer is preferably any of random copolymers and block copolymers. Moreover, the composition which consists of polystyrene resin, a polypropylene resin, and a compatibilizer can also be used for a 2nd surface layer. However, a component having a higher melting point than the polyethylene resin used for the first surface layer is required. As a difference of melting | fusing point, Preferably it is 10 degreeC or more, More preferably, it is 20 degreeC or more.

As a 2nd surface layer, polypropylene homopolymer (homo PP) has a high melting | fusing point and excellent heat resistance among polypropylene resin.

Melt florate (MFR: JIS K 7210) is preferably 0.1 to 60 g / 10 minutes, more preferably 0.3 to 20 g / 10 minutes.

In the present invention, by using a resin having different melting points in the first surface layer and the second surface layer, it is possible to prevent appearance defects during heat sealing.

The adhesive layer interposed between the base layer and the surface layer is made of a polystyrene resin, a polypropylene resin, and a compatibilizer. That is, polypropylene resin is used as polyolefin resin in the intermediate | middle layer of the 1st multilayer structure mentioned above.

The polystyrene resin used for the adhesive layer is the same as the polystyrene resin used as the base material layer and / or the second surface layer. The polystyrene resin of the adhesive layer may be the same as or different from the polystyrene resin of the base layer and / or the second surface layer.

It is preferable that polypropylene resin is the same kind as a 2nd surface layer, More preferably, it is the same thing.

In the present invention, by using a polypropylene resin as the adhesive layer, both the first and second surface layers can be laminated with excellent interfacial strength.

The compounding quantity of polystyrene resin, polypropylene resin, and compatibilizer in a compatibilizer and an adhesive layer is the same as the intermediate | middle layer of the 1st multilayer structure mentioned above.

In addition, as the second multilayer structure, a compatibilizer used in the adhesive layer, in particular, by using SBBS, which is a partial hydrogenated product of SBS, it is possible to suppress the occurrence of the gelation at the time of recycling caused by the conventional EVA-based adhesive at a low cost, and thus, the conventional SIS and SBS The interface strength superior to that in the case of using a system compatibilizer can be obtained.

The thickness of the whole of the second multilayer structure, and the thickness of each layer are the same as the range that each layer of the first multilayer structure can take. In addition, about the 1st surface layer and the 2nd surface layer, it is the same thickness as the surface layer of a 1st multilayer structure, and an adhesive layer is the same thickness as an intermediate | middle layer.

The base material layer, the adhesive layer, and each surface layer may be a lubricant, a softener, a plasticizer, an antioxidant, an antistatic agent, calcium carbonate, talc, magnesium phosphate, aluminum hydroxide, barium sulfate, calcium silicate, titanium oxide, and a release agent within a range that does not impair its properties. And other components. Coloring is also possible.

In addition, the second multilayer structure may further laminate other layers as part of the substrate layer. For example, resin layers, such as ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyamide, and polyethylene terephthalate, can be laminated for the purpose of improving oxygen gas barrier property and reducing deformation in the case of using a container. This layer may be a resin layer containing an inorganic filler.

Similarly to the first multilayer structure, the second multilayer structure can be produced by coextrusion or laminate processing. Usually, the co-extrusion lamination method which laminates the co-extruded 4-layered structure which consists of an adhesive layer, a base material layer, an adhesive layer, and a surface layer of a polypropylene resin film and a polystyrene resin of a molten state is used preferably.

In addition to the characteristics of the first multilayer structure, the second multilayer structure has a first surface layer and a second surface layer having a higher melting point than that of the first multilayer structure.

Therefore, the multilayer structure of the present invention is capable of heat sealing with a polyolefin-based container or package, and also has thermoforming and rigidity of the polystyrene-based resin.

[Container, Cover and Package Made of Second Multi-layer Structure]

The container, cover, and package of the present invention are formed of the sheet-like multilayer structure.

The container, cover, and package of the present invention are obtained by heating and melting the sheet-like multilayer structure into a desired shape, and are preferably obtained by ordinary vacuum forming, pressure forming, or the like. It may also be obtained by molding by injection molding, injection blow molding, blow molding or the like using the above resin.

3 is a cross-sectional view of the second multilayer structure of the present invention.

The multilayer structure 12 shown in FIG. 3 consists of the 1st surface layer 7, the contact bonding layer 8a, the base material layer 3, the contact bonding layer 8b, and the 2nd surface layer 9. As shown in FIG.

4 is a sectional view of a container and a cover made of the second multilayer structure of the present invention.

The container 21 and the cover 31 shown in FIGS. 4A and 4B are made of the multilayer structure 12 of FIG. 3, and the first surface layer 7 of the multilayer structure 12 is on the contents side. The multilayer structure 12 extends to form the flange portion 6.

In addition, although the shape of the flange part 6 of the container 21 and the cover 31 is not specifically limited, Usually, it is circular, a square, etc .. In addition, a container shape may be cup shape or tray shape.

The container and / or cover of the present invention is excellent as a package of food or medicine because of excellent oil resistance, chemical resistance and heat resistance. Specifically, it is used as a package of lunch boxes, tofu, and side dishes.

Moreover, since it hardly gels at the time of recycling, it is excellent in recyclability.

EXAMPLE

Hereinafter, although the Example of this invention is described, this invention is not limited by these Examples.

[First multilayer structure]

The measuring method and evaluation method of the physical property shown in the Example and comparative example which concern on a 1st multilayer structure are as follows.

(1) interlayer strength

15μm biaxially stretched nylon film (Idemitsu Unitech Co., Ltd .: Uniron G100) and 30μm unstretched polypropylene film (Idemitsu Unitech Co., Ltd .: UNILAX RS-510C) A nylon / polypropylene bilayer film was obtained. This film was used as a cover material, and the polypropylene layer was made into the sheet side, and was heat-sealed to the container for evaluation. The conditions were performed at 190 degreeC and the pressure of 0.25 MPa for 3 second.

The sealed portion was cut into a width of 15 mm to obtain a sample for strength measurement.

The intensity | strength in 180 degree peeling (angle of a cover and a container) was measured at 200 mm / min of tensile velocity.

(2) oil resistance

50 mL of Nisse salad oil was put into the container for evaluation, and it heated in the microwave oven (output 600W) for predetermined time, and confirmed the deformation state of the container.

The container was not deformed with a heating time of 3 minutes:

The container was not deformed with a heating time of 2 minutes: O

The vessel was deformed with a heating time of 2 minutes: ×

The container was deformed with a heating time of 1 minute or less: ××

(3) Recyclability (Gelification)

The sheet for evaluation was pulverized by a Horier grinder, melt-extruded by Labotex Co., Ltd., Japan, which provided a single-layer coat hanger die, and the single-layer sheet of 0.5 mm thickness was obtained at the die exit temperature of 230 degreeC.

The single layer sheet was pulverized with a JC-2 type pulverizer manufactured by Morita Seiki Industries Co., Ltd., and the sheet was further produced from Labotex.

After the sheet molding in Labotex was repeated five times by the above method, the appearance of the 0.5 mm thick sheet was visually inspected.

No problem in appearance: ○

Gels and / or soot occur: ×

Occurs before the gel and / or soot is repeated five times: ××

Example 1

Polypropylene (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PP: F-704 NT) (PP1) 100 wt% as a surface layer, impact resistant polystyrene (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PS : ET63) (PS1) 60% by weight, polypropylene (Idemitsu PP: F-704NT) (PP1) 35% by weight, compatibilizer (Asahi Chemical Co., Ltd. product: tough tech P 2000: styrene-butadiene-butylene styrene Copolymer: Glass transition temperature (Tg) -77 DEG C) (Compatibilizer 1) Composition consisting of 5 wt%, and impact-resistant polystyrene (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PS: HT52) (PS2) as a base layer ) Multilayer coextrusion method using 80% by weight of general-purpose polystyrene (product of Idemitsu Petrochemical Co., Ltd. product: Idemitsu PS: HH30) (PS3) 20-layer )

The sheet for evaluation was obtained in which the width of the sheet was 800 mm, the thickness of the surface layer was 25 µm, the thickness of the intermediate layer was 25 µm, and the thickness of the substrate layer was 450 µm.

The obtained sheet was thermoformed in a vacuum press forming machine (FK-0431-10) manufactured by Asano Research Institute so that the surface layer was placed on the contents side, thereby obtaining a container for evaluation (a rectangular container having a height of 140 mm × 140 mm × 60 mm). .

The interlaminar strength, oil resistance and recyclability were evaluated. The evaluation results are shown in Table 1.

Example 2

61 wt% of impact-resistant polystyrene (Idemitsu PS: HT52) (PS2) as the base layer, 35 wt% polypropylene (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PP: E-203GV) (PP2), compatibilizer ( A sheet and a container were obtained by the method of Example 1, except that a composition consisting of 4% by weight of Toughtech P2000) (Compatibilizer 1) was used. The evaluation results are shown in Table 1.

Example 3

Asahi Kasei Co., Ltd. product: Toughtech H1043 (styrene-ethylene-butylene-styrene copolymer: glass transition temperature -64 degreeC) as a compatibilizer of an intermediate | middle layer, The sheet was carried out by the method of Example 1 except having used the compatibilizer 2). And a container was obtained. The evaluation results are shown in Table 1.

Example 4

As a surface layer, the laminated surface of the unstretched polypropylene film (CPP film) (Idemitsu Unitech Co., Ltd. product: UNILAX RS-510C) (PP3) of 25 micrometers thickness is arrange | positioned at the intermediate | middle layer side, The method of Example 1 Thus, the two-layer structure in which only the intermediate layer and the base material layer were extruded by the multilayer coextrusion method was laminated by the extrusion molding method to obtain a three-layer multilayer structure. The sheet | seat for evaluation of 800 mm, the thickness of a surface layer was 25 micrometers, the thickness of an intermediate | middle layer was 25 micrometers, and the thickness of a base material layer was obtained 450 micrometers. About the container for evaluation, it carried out according to the method of Example 1. The evaluation results are shown in Table 1.

Comparative Example 1

Single layer sheet molding at a die exit temperature of 230 ° C. using a composition consisting of 80% by weight of impact-resistant polystyrene (Idemitsu PS: HT52) (PS2) and 20% by weight of general purpose polystyrene (Idemitsu PS: HH30) (PS3) as the substrate layer did. Diluting the polyester-based polyurethane adhesive with ethyl acetate on the laminate surface of the unstretched polypropylene film (Uni-Lax RS-510C) (PP3) having a thickness of 25 μm was applied by laminating by dry laminate method, which was compressed and dried, and then laminated. Obtained. The sheet | seat for evaluation of 800 mm, the thickness of the surface layer, 25 micrometers, and the thickness of the base material layer was 475 micrometers was obtained. About the container for evaluation, it carried out according to the method of Example 1. The evaluation results are shown in Table 1.

Comparative Example 2

An adhesive layer of an EVA-based special unstretched polypropylene film (CPP film) (manufactured by Nippon Ink Chemical Co., Ltd .: DIFAREN280K) (PP4) having a thickness of 25 µm as the surface layer was disposed on the substrate layer side and described by the method described in Example 1. Only the layers were laminated by extrusion molding to obtain a two-layered multilayer structure. The sheet | seat for evaluation of 800 mm, the thickness of the surface layer, 25 micrometers, and the thickness of the base material layer was 475 micrometers was obtained. About the container for evaluation, it carried out according to the method of Example 1. The evaluation results are shown in Table 1.

Comparative Example 3

It carried out according to the method of Example 1 except having used the ethylene-vinyl acetate copolymer (EVA) type adhesive agent (adhesive 1) (made by Tosoh Corporation: Melsen M MX13: vinyl acetate content 18 weight%) as an intermediate | middle layer. The evaluation results are shown in Table 1.

Comparative Example 4

It carried out according to the method of Example 1 except having used the ethylene-vinyl acetate copolymer (EVA) type adhesive agent (adhesive 2) (made by Tosoh Corporation: Melsen M MX11: vinyl acetate content 13 weight%) as an intermediate | middle layer. The evaluation results are shown in Table 1.

Comparative Example 5

60 weight% of impact-resistant polystyrene (Idemitsu PS: ET63) (PS1), 35 weight% of polypropylene (Idemitsu PP: F-704NT) (PP1) as a surface layer of a surface, a compatibilizer (Toughtech P2000) (commercialization) 1) a composition consisting of 5% by weight, and a composition consisting of 80% by weight of impact-resistant polystyrene (Idemitsu PS: HT52) (PS2) and 20% by weight of general purpose polystyrene (Idemitsu PS: HH30) (PS3) The sheet | seat of the above two layers was shape | molded by the multilayer coextrusion method (die outlet temperature 230 degreeC).

The width of the sheet was 800 mm, the thickness of the surface layer was 25 µm, and the thickness of the base layer was carried out in accordance with the method of Example 1, except that the sheet for evaluation was obtained. The evaluation results are shown in Table 1.

Comparative Example 6

61 weight% of impact-resistant polystyrene (Idemitsu PS: HT52) (PS2), 35 weight% of polypropylene (Idemitsu PP: E-203GV) (PP2), 4 weight of compatibilizers (Toughtech P2000) (commercializing agent 1) The single layer sheet was molded at the die exit temperature of 230 ° C using the composition consisting of%.

The sheet was carried out according to the method of Example 1 except that the sheet for evaluation having a width of 800 mm and a thickness of 500 µm was obtained. The evaluation results are shown in Table 1. In addition, the interlaminar strength could not be measured due to the monolayer sheet.

Comparative Example 7

A single-layer sheet of impact resistant polystyrene (Idemitsu PS: HT52) (PS2) 100% by weight was molded at a die exit temperature of 230 deg.

The sheet was carried out according to the method of Example 1 except that the sheet for evaluation having a width of 800 mm and a thickness of 500 µm was obtained. The evaluation results are shown in Table 1. In addition, the interlaminar strength could not be measured due to the monolayer sheet.

PP1: Idemitsu Petrochemical Co., Ltd. product: Idemitsu PP: F-704NT

PP2: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PP: E-203GV

PP3: Idemitsu Unitech Co., Ltd. product: UNILAX RS-510C

PP4: Great Japan ink chemical industry (made): DIFAREN280K

PS1: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: ET63

PS2: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: HT52

PS3: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: HH30

Compatibilizer 1: Asahi Chemical Co., Ltd. Product: Toughtech P2000

Compatibilizer 2: Asahi Hwasung Co., Ltd. Product: Toughtech H1043

EVA Adhesive 1: Tosoh Corporation: Melsen M MX13

EVA adhesive 2: Tosoh Corporation: Melsen M MX11

It can be seen from Table 1 that the sheet of the example has sufficiently high interlaminar strength, excellent oil resistance, and no gelling upon recycling.

[2nd multilayer structure]

The measuring method and evaluation method of the physical property shown in the Example and the comparative example of a 2nd multilayer structure are as follows.

(1) sealed appearance

The first surface layers of the multilayer structure faced each other and were heat sealed on the second surface layer side. The conditions were implemented at 160 degreeC and the pressure of 0.25 MPa for 5 second.

The second surface layer after the heat sealing was visually observed, and there was no appearance defect such as melting, stretching, or surface roughness.

(2) interlayer strength

The first surface layers of the multilayer structure faced each other and were heat sealed on the second surface layer side. The conditions were implemented at 160 degreeC and the pressure of 0.25 MPa for 5 second.

The sealed portion was cut into a width of 15 mm to obtain a sample for strength measurement.

At a tensile rate of 200 mm / min, the strength at 90 degree peeling was measured. As a result, it was assumed that sufficient interlaminar strength was obtained, and that the adhesive strength of the sealing interface was not obtained or that separation occurred between the layers of the multilayer structure.

(3) Recyclability (Gelification)

It implemented by the method similar to the 1st multilayer structure "(3) recyclability" mentioned above.

Example 5

High-density polyethylene (HDPE) (made by Idemitsu Petrochemical Co., Ltd.) as the first surface layer (Idemitsu HD: 110Y: Density 966 kg / m ³ : MFR = 13 g / 10 min: Melting point (Tm) = 131.7 ° C.) (PE1) 100 Weight%, impact resistant polystyrene (HIPS) (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PS: ET63: MFR = 2.58 / 10min) (PS1) 55% by weight, polypropylene (Idemitsu petrochemical) Product: Idemitsu PP: F-704NT: Tm = 164 ℃) (PP1) 35% by weight, compatibilizer (Asahi Chemical Co., Ltd. product: Toughtech P2000: Styrene-butadiene-butylene styrene copolymer (SBBS) ): Glass transition temperature (Tg) =-77 ° C.) (Compatibilizer 1) Composition consisting of 10% by weight, impact resistant polystyrene (HIPS) as a substrate layer (Idemitsu Petrochemical Co., Ltd. product: Idemitsu PS: HT52) (PS2) 80 wt%, general purpose polystyrene (GPPS) (made by Idemitsu Petrochemical Co., Ltd .: 20 wt% of Idemitsu PS: HH30) (PS3), impact resistant polystyrene (IDE) as a second surface layer PS: ET63) (PS1) 55% by weight, polypropylene (Idemitsu PP: F-704 NT) (PP1) 35% by weight, compatibilizer (Toughtech P2000) (commercializing agent 1) 10% by weight of the composition The five layers of sheets were molded by a multilayer coextrusion method (die exit temperature 230 ° C.).

An evaluation sheet having an overall thickness of 500 μm was obtained in which the width of the sheet was 800 mm, the thickness of the first surface layer was 25 μm, the thickness of the adhesive layer was 25 μm, the thickness of the second surface layer was 25 μm, and the base layer was 400 μm.

The sheet thus obtained was thermoformed using a vacuum pressure molding machine (FK-0431-10) manufactured by Asano Research Institute so that the first surface layer was placed on the contents side, and an evaluation container (a square container having a height of 140 mm × 140 mm × 60 mm) was used. Obtained.

Seal appearance, interlayer strength, and recyclability were evaluated. The evaluation results are shown in Table 2.

Example 6

A sheet and a container were obtained by the method of Example 5 except that 100% by weight of polypropylene (Idemitsu PP: F-704NT) (PP1) was used as the second surface layer. The evaluation results are shown in Table 2.

Example 7

As a compatibilizer for the adhesive layer and the second surface layer, the product was carried out except that Asahi Chemical Co., Ltd. product: Toughtech H1043 (styrene-ethylene-butylene styrene copolymer (SBBS): Tg = -64 ° C.) (compatibility agent 2) was used. The sheet and the container were obtained by the method of Example 5. The evaluation results are shown in Table 2.

Example 8

A laminate surface of an unstretched polypropylene film (CPP film) having a thickness of 25 μm (CPP film) (product of Idemitsu Unitec Co., Ltd .: UNILAX RS-510C: melting point 163.7 ° C) (PP2) as a second surface layer was disposed on the adhesive layer side. The four-layer structure obtained by extruding only the first surface layer, the adhesive layer, the substrate layer, and the adhesive layer by the multilayer coextrusion method by the method described in Example 5 was laminated by the extrusion molding method to obtain a five-layer multilayer structure. An evaluation sheet having an overall thickness of 500 μm was obtained in which the width of the sheet was 800 mm, the thickness of the first surface layer was 25 μm, the thickness of the adhesive layer was 25 μm, the thickness of the second surface layer was 25 μm, and the thickness of the base layer was 400 μm. About the container for evaluation, it carried out according to the method of Example 5. The evaluation results are shown in Table 2.

Comparative Example 8

100 weight% of high density polyethylene (Idemitsu HD: 110Y) (PE1) as a 1st surface layer, 78 weight% of impact-resistant polystyrene (Idemitsu PS: ET63) (PS1) as an intervening adhesive layer, high density polyethylene (Idemitsu HD: 110Y) (PE1) 12% by weight, a compatibilizer (Asahi Chemical Co., Ltd. product: Tafrene TP126: styrene-butadiene-styrene copolymer (SBS): T8 = -70 ℃) (compatibility 3) a composition consisting of 10% by weight , Composition consisting of 80% by weight of impact-resistant polystyrene (Idemitsu PS: HT52) (PS2), 20% by weight of general purpose polystyrene (Idemitsu PS: HH30) (PS3), impact-resistant polystyrene (Idemitsu) as a second surface layer PS: ET63) (PS1) 78% by weight, high density polyethylene (Idemitsu HD: 110Y) (PE1) 12% by weight, compatibilizer (taphrene TP126) (compatibility agent 3) 5 layers using a composition The sheet of was molded by the multilayer coextrusion method (die exit temperature 230 degreeC).

An evaluation sheet having an overall thickness of 500 μm was obtained in which the width of the sheet was 800 mm, the thickness of the first surface layer was 25 μm, the thickness of the adhesive layer was 25 μm, the thickness of the second surface layer was 25 μm, and the base layer was 400 μm. About the container for evaluation, it carried out according to the method of Example 5. The evaluation results are shown in Table 2.

Comparative Example 9

A sheet and a container were obtained by the method of Example 5 except that polypropylene (Idemitsu PP: F-704NT) (PP1) was used as the second surface layer. The evaluation results are shown in Table 2.

Comparative Example 10

As the second surface layer, a laminate surface of a non-stretched polypropylene film (Unilax RS-510C) (PP2) having a thickness of 25 μm was disposed on the adhesive layer side, and the first surface layer, the adhesive layer, the substrate layer, and the adhesive layer were prepared by the method described in Comparative Example 8. The four-layer structure in which only the bay was extruded by the multilayer coextrusion method was laminated by the extrusion molding method to obtain a five-layer multilayer structure. An evaluation sheet having an overall thickness of 500 μm was obtained in which the width of the sheet was 800 mm, the thickness of the first surface layer was 25 μm, the thickness of the adhesive layer was 25 μm, the thickness of the second surface layer was 25 μm, and the base layer was 400 μm. About the container for evaluation, it carried out according to the method of Example 5. The evaluation results are shown in Table 2.

Comparative Example 11

As the second surface layer, a laminate surface of an unstretched polypropylene film (Uni-Lax RS-510C) (PP2) having a thickness of 25 μm was disposed on the adhesive layer side, and only the first surface layer, the adhesive layer, the substrate layer, and the adhesive layer were prepared by the method described in Comparative Example 8. The four-layer structure extruded by the multilayer coextrusion method was laminated by the dry lamination method to obtain a five-layer multilayer structure. An evaluation sheet having an overall thickness of 500 μm was obtained in which the width of the sheet was 800 mm, the thickness of the first surface layer was 25 μm, the thickness of the adhesive layer was 25 μm, the thickness of the second surface layer was 25 μm, and the base layer was 400 μm. About the container for evaluation, it carried out according to the method of Example 5. The evaluation results are shown in Table 2.

PE1: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu HD: 110Y

PP1: Idemitsu Petrochemical Co., Ltd. product: Idemitsu PP: F-704NT

PP2: Idemitsu Unitech Co., Ltd. product: UNILAX RS-510C

PS1: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: ET63

PS2: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: HT52

PS3: Idemitsu Petrochemical Co., Ltd.Product: Idemitsu PS: HH30

Compatibilizer 1: Asahi Hwasung Co., Ltd. Product: Tough Tech P2000

Compatibilizer 2: Asahi Hwasung Co., Ltd. Product: Toughtech H1043

Compatibilizer 3: Asahi Chemical Co., Ltd.

From Table 2, it can be seen that the sheet of the example has sufficiently high interlaminar strength, excellent heat sealability, no appearance defects, and no gelation upon recycling.

According to the present invention, a polystyrene-based multilayer structure and a package excellent in oil resistance, heat sealability and recyclability are obtained.

Claims (11)

In the base layer made of polystyrene resin, 25% to 75% by weight of polystyrene resin, 75% to 25% by weight of polyolefin resin, and 30% to 80% by weight of aromatic aromatic vinyl and 35% of double bonds based on conjugated diene. Through an intermediate layer containing 1 to 20 parts by weight of a compatibilizer composed of a block copolymer of an aromatic vinyl saturated with hydrogen and a conjugated diene (about 100 parts by weight of the polystyrene resin and the polyolefin resin). , Surface layer made of polyolefin resin Multilayer structure. A double layer based on a conjugated diene having 25 to 75% by weight of polystyrene resin, 75 to 25% by weight of polyolefin resin, and 30 to 80% by weight of bonded aromatic vinyl in a substrate layer composed of polystyrene resin and polyolefin resin. A surface layer made of a polyolefin resin was formed through an intermediate layer composed of a compatibilizer composed of a block copolymer of aromatic vinyl and conjugated diene saturated with hydrogen by 35% or more of the bond. Multilayer structure. On the base layer made of polystyrene resin, a first surface layer made of polyethylene resin and a second surface layer made of polypropylene resin are formed through an adhesive layer made of polystyrene resin, polypropylene resin and compatibilizer. Multilayer structure. A first surface layer made of polyethylene-based resin and a second surface layer made of polystyrene-based resin, polypropylene-based resin, and a compatibilizer, through an adhesive layer made of polystyrene-based resin, polypropylene-based resin, and a compatibilizer, on a substrate layer made of polystyrene-based resin. Formed Multilayer structure. The method of claim 3, wherein A double bond based on a conjugated diene based on a conjugated diene is contained in the base layer made of polystyrene resin, and the polystyrene resin is 25 to 75% by weight, the polypropylene resin is 75 to 25% by weight, and the bonded aromatic vinyl content is 30 to 80% by weight. An adhesive layer containing 1 to 20 parts by weight of a compatibilizer composed of a block copolymer of an aromatic vinyl and a conjugated diene saturated with at least% hydrogen, which is based on 100 parts by weight of the polystyrene resin and the polypropylene resin. Through, a multi-layered structure having a first surface layer made of polyethylene-based resin and a second surface layer made of polypropylene-based resin. The method of claim 4, wherein A double bond based on a conjugated diene based on a conjugated diene is contained in the base layer made of polystyrene resin, and the polystyrene resin is 25 to 75% by weight, the polypropylene resin is 75 to 25% by weight, and the bonded aromatic vinyl content is 30 to 80% by weight. An adhesive layer containing 1 to 20 parts by weight of a compatibilizer composed of a block copolymer of an aromatic vinyl and a conjugated diene saturated with at least% hydrogen, which is based on 100 parts by weight of the polystyrene resin and the polypropylene resin. Through the first surface layer made of polyethylene resin, and 25 to 75% by weight of polystyrene resin, 75 to 25% by weight polypropylene resin, and 2 to 80% by weight of aromatic aromatic vinyl, based on conjugated diene. 1 to 20 parts by weight of a compatibilizer comprising a block copolymer of an aromatic vinyl and a conjugated diene saturated with at least 35% of hydrogen bonds Polystyrene-based resin and the polypropylene will on 100 parts by weight of the combination of the resin) the combination a multi-layer structure of claim 2, the surface layer is formed. The method according to claim 3 or 4, A multilayer structure wherein the compatibilizer of the adhesive layer and / or the second surface layer is a hydrogenated product of a block copolymer of aromatic vinyl and conjugated diene. The method according to claim 1 or 2, The multilayer structure in which the polyolefin resin of a surface layer is a polypropylene resin. The method according to any one of claims 1 to 4, The multilayer structure of which the glass transition temperature of a compatibilizer is -60 degrees C or less. A multilayered structure according to claim 1 or 2, wherein the surface layer is directed towards the contents Container, cover or package. A multi-layered structure according to any one of claims 3 to 6, wherein the first surface layer faces the contents. Container, cover or package.