JP2005111888A - Resin-expanded laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin sheet which is light in weight and high in mechanical strength such as rigidity, has high glossiness, and is excellent in appearance and a container formed from the sheet. <P>SOLUTION: A non-foamed layer (B) formed from a resin composition containing a styrene resin (b1), an olefin resin (b2) having a melt flow rate according to JIS K 7210 of at least 0.4 and below 3 (especially 0.5-2), and an aromatic vinyl-diene copolymer (b3) is formed on at least one surface of a foamed layer (A) formed from a resin composition containing a styrene resin (a1), an olefin resin (a2) having a melt flow rate according to JIS K 7210 of at least 0.4 and below 3 (especially 0.5-2), and an aromatic vinyl-diene copolymer (a3) to prepare a laminated sheet. In the foamed layer (A) and the non-foamed layer (B), the styrene resin contains at least a non-rubber-containing styrene resin, and the olefin resin can be a propylene resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin foam laminated sheet that is excellent in appearance, heat resistance, oil resistance, container moldability, and the like and is suitable for reducing the weight of a molded product, and a container formed of this sheet.

  In recent years, stores such as supermarkets and convenience stores have been selling take-out side dishes and bento boxes in plastic containers and are used by consumers. These foods are often used after being reheated in a microwave oven together with the container. As the characteristics of the container to be used, heat resistance so as not to be deformed by a microwave oven and rigidity necessary for placing the contents, closing the lid, and carrying the contents are required. Furthermore, from the viewpoint of improving the sales volume at the store, the container is also required to have high glossiness for producing a high-class feeling.

  Conventionally, styrenic resins have been widely used as containers for various foods due to their excellent moldability and rigidity, but styrene resins have poor heat resistance, so when heated in a microwave oven for each food container The container is deformed. In order to prevent such deformation, a method of coating the surface of a container made of styrene resin with a heat-resistant resin sheet is known, but the manufacturing process becomes complicated and the manufacturing cost increases.

  In JP-A-2000-103016 (Patent Document 1), a polyolefin resin layer is laminated on at least one surface of a polystyrene resin foam layer via an alloy layer made of a mixed resin of a polystyrene resin and a polyolefin resin. A polystyrene resin foam / polyolefin resin multilayer body in which the adhesive strength between the foam layer and the polyolefin resin layer is 40 gf / cm or more is disclosed. However, even this multilayer body has insufficient heat resistance and adhesion between layers.

  In addition, as a container in which deformation due to heating of a microwave oven is suppressed, a container obtained by thermoforming a sheet filled with 20 to 55% by weight of an inorganic material such as talc or calcium carbonate with respect to a polypropylene resin is also known. This container is widely used as a container that does not deform when heated in a microwave oven with food in it. However, since this container has low heat insulating properties, it is difficult to hold the container with bare hands when taking it out after heating in a microwave oven.

  In order to improve the heat insulation, Japanese Patent Application Laid-Open No. 1-200931 (Patent Document 2) proposes a container formed of a sheet obtained by extrusion foaming a polypropylene resin filled with inorganic fine powder. However, in order to produce a foam sheet having an excellent appearance, a special extruder is required, and molding of a container using such a sheet has low productivity. In addition, in order to reduce the burden of the obligation for re-commercialization under the “Container Recycling Law” which was fully enforced in April 2000, it is desired to reduce the weight of the container, which is not sufficient from the viewpoint of light weight.

  As a method for producing a sheet having high rigidity and heat resistance to a microwave oven, a method of mixing a styrene resin and a heat resistant resin such as a propylene resin is also known. For example, Japanese Patent Laid-Open No. 10-330522 (Patent Document 3) discloses that an inorganic filler 5 is added to 95 to 40 parts by weight of a thermoplastic resin composed of 45 to 95% by weight of a polypropylene resin and 55 to 5% by weight of a polystyrene resin. A thermoplastic resin resin foamed sheet obtained by foaming a resin composition containing ˜60 parts by weight up to 1.05 to 3 times is disclosed. However, even in this sheet, the proportion of the inorganic filler is large and the weight of the container is not reduced.

  In Japanese Patent No. 3333883 (Patent Document 4), (a) 50 to 80% by weight of styrene-based resin and (b) 20 to 50% by weight of propylene-based resin are combined with 100 parts by weight of (c) styrene- A composition containing 1 to 30 parts by weight of a hydrogenated isoprene block copolymer and a styrene resin composition that defines a melt viscosity ratio between a styrene resin and a propylene resin is disclosed. However, such a method for defining the melt viscosity ratio cannot stably supply a sheet having excellent heat resistance and appearance characteristics.

  JP-A-8-48842 (Patent Document 5) contains an occlusion structure and a rubber-modified styrene resin having a specific viscosity ratio, a polyolefin resin, and a styrene-butadiene-styrene block copolymer. A resin composition having a rubber-modified styrene resin content of 60 to 90% by weight, a polyolefin resin content of 5 to 35% by weight, and a styrene-butadiene-styrene block. A styrene-based resin composition having a copolymer content of 5 to 20% by weight is disclosed. In JP-A-10-182923 (Patent Document 6), a rubber-modified styrene resin (A) having an average rubber particle diameter of 0.1 to 1.5 μm, an olefin resin having a melt flow rate of 1 to 15 g / 10 min ( B), and a styrene resin composition comprising a block copolymer (C) of a styrene monomer and a conjugated diene monomer, or a styrene resin foam sheet formed from this composition, It is disclosed. In this document, the weight ratio of the rubber-modified styrene resin (A) to the olefin resin (B) is (A) / (B) = 50/50 to 95/5, and the block copolymer (C) The weight ratio of (C) / [(A) + (B)] = (1-40) / 100. However, although these sheets have a relatively smooth surface, the glossiness of the surface is low.

Japanese Patent Application Laid-Open No. 2001-59037 (Patent Document 7) discloses a foam obtained by foaming a resin composition containing a styrene resin (A) and a propylene resin (B). A styrene resin foam is disclosed in which the propylene resin (B) forms a layered structure, the foam density is 0.5 g / cm ³ or less, and the closed cell ratio is 20% or more. This document describes that the ratio ((B) / (A)) of the melt flow index of the styrene resin (A) to the propylene resin (B) is 0.01 to 20, 1-30 parts by weight of a compatibilizing agent (C) such as a polymer is added to 100 parts by weight in total of 50-90 parts by weight of the styrene resin (A) and 10-50 parts by weight of the propylene resin (B). It is described that it may be. Furthermore, it is described that a film may be laminated on the foam as necessary. However, this foam has a high expansion ratio and a lighter container, but has low surface gloss, low rigidity, and is easily bulky.

  In Japanese Patent No. 3024114 (Patent Document 8), the total amount of (A) styrene resin 5 to 95% by weight and (B) 95 to 5% by weight of a crystallized thermoplastic resin having a melt flow rate of 3 or more. On the other hand, the thermoplastic resin sheet obtained by molding a resin composition containing 0.1 to 20 parts by weight of a compatibilizer (such as a styrene-butadiene block copolymer) or obtained by foam molding the composition. A foam sheet is disclosed. This document describes a laminate of two or more layers of this sheet and a resin non-foamed sheet. However, this sheet is excellent in moldability and heat resistance, but has low gloss and is insufficient in lightness and rigidity.

As described above, in the foam sheet, it is generally difficult to increase rigidity and surface gloss while reducing the weight.
JP 2000-103016 A (Claim 1) Japanese Patent Laid-Open No. 1-200931 (Claim 1) Japanese Patent Laid-Open No. 10-330522 (Claim 1) Japanese Patent No. 3338083 (Claim 1) JP-A-8-48842 (Claim 1) JP-A-10-182923 (Claims 1-2 and 8) JP 2001-59037 A (Claims 1-2, paragraph number [0026]) Japanese Patent No. 3024114 (Claims 1 to 4 and 6)

  Accordingly, an object of the present invention is to provide a resin sheet that is lightweight, has high mechanical strength such as rigidity, has high gloss, and has an excellent appearance, and a container formed of the sheet.

  Another object of the present invention is to provide a resin sheet having high heat resistance, oil resistance and moldability, and a container formed of the sheet.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventor was composed of a resin composition containing a styrene resin, an olefin resin having a specific melt flow rate, and an aromatic vinyl-diene copolymer. By laminating the foamed layer with a non-foamed layer composed of a resin composition having the same composition as the foamed layer, it has high mechanical strength such as rigidity and high glossiness despite being lightweight. As a result, the present invention was completed.

  That is, the laminated sheet of the present invention comprises a styrene resin (a1), an olefin resin (a2) having a melt flow rate in accordance with JIS K 7210 of 0.4 or more and less than 3 (particularly 0.5 to 2), and On at least one surface of the foamed layer (A) composed of the resin composition containing the aromatic vinyl-diene copolymer (a3), a styrene resin (b1) and a melt flow rate based on JIS K 7210 are provided. Non-foamed layer (B) composed of a resin composition comprising an olefin resin (b2) that is 0.4 or more and less than 3 (particularly 0.5 to 2) and an aromatic vinyl-diene copolymer (b3) ) Is formed. In the foam layer (A) and the non-foam layer (B), the styrene resin (a1) and / or (b1) contains at least a non-rubber-containing styrene resin, and the olefin resin (a2) and / or (b2) Polypropylene resin may be used. The aromatic vinyl-diene copolymer may be a styrene-butadiene block copolymer. In the non-foamed layer (B), the styrene resin (b1) is composed of a non-rubber-containing styrene resin and a rubber-modified styrene resin, and the ratio of the rubber-modified styrene resin in the non-foamed layer (B) is It may be 5% by weight or less (particularly 3% by weight or less). In the foam layer (A), the ratio (weight ratio) between the styrene resin (a1) and the olefin resin (a2) is styrene resin (a1) / olefin resin (a2) = 30/70 to 95/5. (Particularly 50/50 to 90/10), and the ratio of the aromatic vinyl-diene copolymer (a3) is 100 parts by weight in total of the styrene resin (a1) and the olefin resin (a2). The olefin resin (b2) and the aromatic vinyl-diene copolymer (b3) in the non-foamed layer (B) are about 0.1 to 30 parts by weight (particularly 0.5 to 20 parts by weight). ) May be the same or larger than the ratio of the olefin resin (a2) and the aromatic vinyl-diene copolymer (a3) in the foamed layer (A). In the sheet, the expansion ratio of the foam layer (A) is 1.05 to 2 times, and the ratio of the foam layer (A) is about 40 to 90% by weight with respect to the whole sheet. In the sheet, the surface gloss at an incident angle of 60 ° according to JIS K 7105 is 10% or more, and the center line average roughness Ra according to JIS B 0601 is about 0.1 to 1 μm. The sheet may have a non-foamed layer (B) formed on both sides of the foamed layer (A).

  The present invention also includes a laminated sheet in which a resin layer (C) is further formed on at least one surface of the sheet. This resin layer (C) may be composed of a styrene resin or an olefin resin that may be printed.

  The present invention includes a styrene resin (a1), an olefin resin (a2) having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210, and an aromatic vinyl-diene copolymer (a3). On at least one surface of the foamed layer (A) composed of a resin composition containing styrene resin (b1), an olefin resin having a melt flow rate in accordance with JIS K 7210 of 0.4 or more and less than 3. Also included is a method for producing a laminated sheet that forms a non-foamed layer (B) composed of a resin composition containing b2) and an aromatic vinyl-diene copolymer (b3). The present invention also includes a container formed of the sheet. Furthermore, in the present invention, at least one surface of the foam layer (A) composed of a resin composition containing a styrene resin, an olefin resin, and an aromatic vinyl-diene copolymer, a styrene resin, A method for improving the mechanical strength and surface gloss of a laminated sheet formed with a non-foamed layer (B) composed of an olefin resin and a resin composition containing an aromatic vinyl-diene copolymer, As the olefin resin constituting the foam layer (A) and the non-foam layer (B), an olefin resin having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210 is used, and the mechanical strength of the laminated sheet And methods for improving surface gloss are also included.

  In the present invention, a resin sheet and a container having high mechanical strength such as rigidity, high gloss, and excellent appearance are obtained despite being lightweight. Furthermore, a resin sheet and a container having high heat resistance, oil resistance, and moldability are obtained.

[Foamed layer]
The foam layer comprises a styrene resin (a1), an olefin resin (a2) having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210, and an aromatic vinyl-diene copolymer (a3). It is comprised with the resin composition containing.

(a1) Styrenic Resin The styrene resin (a1) is a homopolymer or a copolymer formed with an aromatic vinyl monomer as a main structural unit. Examples of the aromatic vinyl monomer for forming the styrene-based resin include styrene, alkyl-substituted styrene (for example, vinyltoluene such as 2-methylstyrene, ethylstyrene such as 4-ethylstyrene, 4-isopropylstyrene, etc. Propyl styrene, butyl styrene such as 4-butyl styrene and 4-t-butyl styrene), and α-alkyl substituted styrene substituted with an alkyl group at the α-position (for example, α-methyl styrene, α-methyl-4-methyl) Styrene), halogen-substituted styrene (for example, chlorostyrene such as 2-chlorostyrene and 4-chlorostyrene, bromostyrene such as 2-bromostyrene and 4-bromostyrene), and the like. These aromatic vinyl monomers can be used alone or in combination of two or more. Of these monomers, styrene, vinyltoluene, α-methylstyrene, particularly styrene is usually used.

The aromatic vinyl monomer may be used in combination with a copolymerizable monomer. Examples of the copolymerizable monomer include acrylic monomers [for example, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) (Meth) acrylic acid C _1-20 (especially C _1-8 ) alkyl esters such as hexyl acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate Hydroxy (meth) acrylates such as phenyl (meth) acrylate, benzyl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, etc. _2-4, such as alkyl esters, vinyl cyanide monomer (e.g., acrylonitrile, etc.), unsaturated polycarboxylic acid or its acid anhydride (E.g., maleic acid, itaconic acid, citraconic acid or an acid anhydride thereof), imide monomer [e.g., maleimide, N- alkylmaleimides (e.g., N-C, such as N- methyl maleimide and N- ethylmaleimide _1-4 alkylmaleimide), N-cycloalkylmaleimide (for example, N-cyclohexylmaleimide), N-arylmaleimide (for example, N-phenylmaleimide)] and the like. These copolymerizable monomers can be used alone or in combination of two or more. The amount of the copolymerizable monomer in all monomers can be selected from the range of usually 1 to 50 mol%, preferably 3 to 40 mol%, more preferably about 5 to 30 mol%.

  The styrene resin (a1) may be a rubber-modified styrene resin. Rubber-modified styrenic resins are used to improve impact resistance and buffering properties, and rubbery polymers are formed in a matrix composed of the styrenic resin by copolymerization (graft polymerization, block polymerization, etc.). It may be a polymer dispersed in the form of particles. Usually, at least an aromatic vinyl monomer is used in the presence of a rubber-like polymer in the usual manner (bulk polymerization, bulk suspension polymerization, solution polymerization, emulsion polymerization, etc. ) Is a graft copolymer (rubber-grafted polystyrene polymer) obtained by polymerization.

Examples of the rubber-like polymer include diene rubber [polybutadiene (low cis type or high cis type polybutadiene), butadiene-isoprene copolymer, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, butadiene. -Acrylonitrile copolymer, isobutylene-isoprene copolymer, styrene-isobutylene-butadiene copolymer rubber, etc.], ethylene-vinyl acetate copolymer, acrylic rubber (based on polyacrylic acid C _2-8 alkyl ester) Copolymer elastomers, etc.), ethylene-α-olefin copolymers [ethylene-propylene rubber (EPR), etc.], ethylene-α-olefin-polyene copolymers [ethylene-propylene-diene rubber (EPDM), etc.], urethane rubber , Silicone rubber, butyl rubber, Attachment diene rubber (hydrogenated styrene - butadiene copolymer, and hydrogenated butadiene polymer) and the like. The copolymer may be a random or block copolymer. Examples of the block copolymer include a copolymer having an AB type, ABA type, tapered type, or radial teleblock type structure. . These rubbery polymers can be used alone or in combination of two or more.

  A preferred rubbery polymer is a polymer of conjugated 1,3-diene or a derivative thereof, particularly a diene rubber [polybutadiene (butadiene rubber), isoprene rubber, styrene-butadiene copolymer, etc.].

  In the rubber-modified styrene resin, the content of the rubber-like polymer is, for example, about 0.5 to 50% by weight, preferably about 1 to 30% by weight, and more preferably about 1 to 20% by weight. If the content of the rubbery polymer is too small, the effect of improving the impact resistance is not sufficient, and if the content of the rubbery polymer is too large, the rigidity is lowered.

  The form of the rubber-like polymer dispersed in the matrix composed of the styrene resin is not particularly limited, and may be a salami structure, a core / shell structure, an onion structure, or the like.

  The particle diameter of the rubber-like polymer constituting the dispersed phase is, for example, in the range of volume average particle diameter of 0.5 μm or more (for example, 0.5 to 30 μm), preferably 1 to 10 μm, more preferably about 2 to 5 μm. You can choose. The graft ratio of the rubbery polymer is about 5 to 150%, preferably about 10 to 150%.

  The melt flow rate of the styrenic resin (a1) is 0.5 to 20, preferably 1 to 8, more preferably 1 in a method (temperature: 200 ° C., load: 5 kgf (49 N)) according to JIS K 7210. About 5-4.

  The weight average molecular weight of the styrene resin (a1) (matrix resin in the case of a rubber-modified styrene resin) is 10,000 to 1,000,000, preferably 50,000 to 500,000, more preferably 100,000. About 500,000.

  These styrenic resins (a1) can be used alone or in combination of two or more. Among these styrene resins (a1), polystyrene (GPPS), styrene-acrylonitrile copolymer (AS resin), styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer (SMA resin), etc. Non-rubber-containing styrene resin (styrene resin not containing rubber component, non-rubber reinforced styrene resin, etc.), impact polystyrene (HIPS), styrene-acrylonitrile-butadiene copolymer (ABS resin), α-methyl Rubber-modified styrene resins such as styrene-modified ABS resin, imide-modified ABS resin, and MBS resin are preferable, and GPPS and HIPS are particularly preferable. In the present invention, it is preferable to include at least a non-rubber-containing styrene resin (such as GPPS). Further, the styrene resin (a1) may be a styrene resin regenerated by recycling.

  In consideration of the balance of impact resistance, rigidity and moldability, a non-rubber-containing styrene resin and a rubber-modified styrene resin may be combined. The ratio (weight ratio) between the non-rubber-containing styrene resin and the rubber-modified styrene resin can be selected from the range of the former / the latter = 100/0 to 10/90, and the former / the latter from the viewpoint of the balance of various properties. = 100/0 to 20/80, preferably 100/0 to 30/70, more preferably about 100/0 to 50/50 (for example, 99/1 to 50/50).

(a2) Olefin-based resin In the present invention, the melt flow rate of the olefin-based resin (a2) is 0. 4 or more and less than 3 (e.g., 0.4-2), preferably 0.5-2 (e.g., 0.5-1.5), more preferably 0.5-1 (e.g., 0.6- 1) About. If the melt flow rate is too small, the compatibility with the styrenic resin (a1) decreases, and the sheet appearance deteriorates. On the other hand, if the melt flow rate is too high, the gloss of the sheet is lowered, a high-quality feeling cannot be obtained, and the closed cell ratio is lowered, so that the weight of the container cannot be reduced. In the present invention, by using an olefin resin having a melt flow rate in such a range, mechanical properties such as rigidity and heat resistance can be improved in a balanced manner while being reduced in weight by foaming.

Examples of the olefin resin (a2) include olefin homo- or copolymers. Examples of the olefin include ethylene, propylene, 1-butene, isobutene, 4-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-octene, Α-C _2-16 olefins such as nonene, 1-decene, 1-undecene, 1-dodecene (preferably α-C _2-10 olefins, more preferably α-C _2-8 olefins, especially α-C _{2- 4} olefins). These olefins may be used alone or in combination of two or more. Of these olefins, ethylene, propylene, particularly at least propylene is preferably contained.

  The olefin resin (a2) may be a copolymer of an olefin and a copolymerizable monomer. As the copolymerizable monomer, for example, the aromatic vinyl monomer exemplified in the section of the styrene resin (a1), a monomer copolymerizable with the aromatic vinyl monomer, and vinyl esters ( Examples thereof include vinyl acetate and vinyl propionate), cyclic olefins (such as norbornene, ethylidene norbornene, cyclopentene, cyclopentadiene and cyclohexene) and dienes (such as butadiene, isoprene and 1,4-pentadiene). A copolymerizable monomer can be used individually or in combination of 2 or more types. The usage-amount of a copolymerizable monomer can be selected from the range of about 0-100 mol with respect to 100 mol of olefins, Preferably it is 0-50 mol, More preferably, it is about 0-25 mol.

  Examples of the olefin resin (a2) include polyethylene resins [for example, low, medium or high density polyethylene, linear low density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene- Propylene-butene-1 copolymer, ethylene- (4-methylpentene-1) copolymer, etc.], polypropylene resin (eg, polypropylene, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene) -Propylene-containing 80 mol% or more propylene-α-olefin copolymer such as ethylene-butene-1 copolymer), poly (methylpentene-1) resin and the like. Examples of the copolymer include ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer or its ionomer, ethylene- (meth) acrylate copolymer such as ethylene-ethyl acrylate copolymer, Examples include maleic anhydride grafted polypropylene.

  The copolymer (a copolymer of olefins and a copolymer of an olefin and a copolymerizable monomer) includes a random copolymer, a block copolymer, or a graft copolymer.

  Of these olefin resins, polypropylene resins are preferred from the viewpoints of heat resistance, oil resistance, strength and rigidity. The polypropylene resin is specifically a propylene homopolymer or a propylene-α-olefin copolymer, and the ratio (molar ratio) of propylene and α-olefin is propylene / α-olefin = 60 / 40-100. / 0, preferably 70/30 to 100/0, more preferably about 80/20 to 100/0 (especially 90/10 to 100/0). When the proportion of α-olefin exceeds 40 mol%, rigidity and heat resistance are lowered.

  The polypropylene resin may have an atactic structure, but may have high stereoregularity such as an isotactic, syndiotactic, or metallocene structure generated by a metallocene catalyst. Among these, a polypropylene resin having an isotactic structure is preferable from the viewpoint of simplicity and economy.

  Furthermore, in order to improve the expansion ratio and closed cell ratio of the foam layer, and to improve the appearance and moldability, it may be combined with ultra-high molecular weight polyolefin, polyolefin having a branched structure, polystyrene graft polyolefin, cyclic polyolefin, etc. .

  The ratio (weight ratio) between the styrene resin (a1) and the olefin resin (a2) can be selected from the range of styrene resin (a1) / olefin resin (a2) = 30/70 to 99/1, preferably Is about 40/60 to 95/5, more preferably about 50/50 to 90/10 (especially 60/40 to 85/15). If the proportion of the styrene resin (a1) is too small, the rigidity and vacuum formability of the sheet are impaired, and if it is too large, the practical heat resistance is lowered.

(a3) Aromatic vinyl-diene copolymer In order to improve the compatibility and impact resistance of styrene resin (a1) and olefin resin (a2), aromatic vinyl-diene copolymer (a3 ) Is used.

  Examples of the aromatic vinyl-diene copolymer include the aromatic vinyl monomer exemplified in the section of the styrene resin (a1) and butadiene, chloroprene, isoprene, 1,3- or 1,4-pentadiene. Copolymers obtained from diene monomers are included, and examples thereof include styrene-butadiene random or block copolymers, styrene-isoprene random or block copolymers, and hydrogenated products thereof. The aromatic vinyl-diene copolymer may be an epoxidized styrene-diene copolymer. The ratio (molar ratio) between the aromatic vinyl component and the diene component constituting the copolymer is aromatic vinyl component / diene component = 55/45 to 95/5, preferably 60/40 to 90/10, More preferably, it is about 65/35 to 75/25. Examples of the structure of the aromatic vinyl-diene block copolymer include linear (linear) type (AB type, ABA type, etc.), star type (radial teleblock type, etc.), and tapered type.

  These aromatic vinyl-diene copolymers (a3) can be used alone or in combination of two or more. Of these, styrene-butadiene block copolymers (for example, di- or triblock copolymers composed of polystyrene blocks and polybutadiene blocks) are preferable.

  The ratio of the aromatic vinyl-diene copolymer (a3) is 0.1 to 30 parts by weight, preferably 0.5 to 100 parts by weight in total of the styrene resin (a1) and the olefin resin (a2). -20 parts by weight (for example, 1-20 parts by weight), more preferably about 3-15 parts by weight (particularly 5-15 parts by weight). If the ratio of the aromatic vinyl-diene copolymer (a3) is too small, the laminated sheet tends to break, and if it is too much, the rigidity as the laminated sheet is lowered and the foamed layer is foamed. It is easy to become.

  The resin composition constituting the foam layer (A) includes inorganic pigments (white pigments such as titanium oxide, yellow pigments such as titanium yellow, red pigments such as iron oxide red, green pigments such as chrome green, cobalt blue, etc. Blue pigments, black pigments such as carbon black), organic colorants (azo dyes, phthalocyanine dyes, lake dyes, etc.), extenders (calcium carbonate, barium sulfate, aluminum hydroxide, mica, talc, alumina, bentonite) And pigment components such as magnesium oxide) may be contained. These pigment components can be used alone or in combination of two or more. Of these pigment components, white pigments such as titanium oxide and black pigments such as carbon black are widely used.

  The ratio of the pigment component is, for example, 0.1 to 30 parts by weight with respect to 100 parts by weight in total of the styrene resin (a1), the olefin resin (a2), and the aromatic vinyl-diene copolymer (a3). The amount is preferably about 0.3 to 20 parts by weight, more preferably about 0.5 to 10 parts by weight.

  For the resin composition constituting the foam layer (A), if necessary, conventional additives such as other thermoplastic resins (acrylic resins, vinyl resins, polyamide resins, polyester resins, polyethers) Resins, polyvinyl ketone resins, polyphenylene oxide resins, etc.), stabilizers (antioxidants, UV absorbers, light stabilizers, heat stabilizers, etc.), flame retardants (phosphorous flame retardants, halogen flame retardants) , Inorganic flame retardants, etc.), flame retardant aids, reinforcing materials (fiber fillers such as glass fibers and carbon fibers), nucleating agents, lubricants, plasticizers, mold release agents (silicone, etc.), impact resistance improvers , Hue improvers, fluidity improvers, dispersants (such as higher fatty acid salts), conductivity imparting agents, antistatic agents, antibacterial agents, and the like may be added. These additives can be used alone or in combination of two or more.

  The thickness of the foam layer (A) is, for example, about 0.2 to 1.8 mm, preferably about 0.2 to 1.3 mm, and more preferably about 0.3 to 1 mm.

  The average number of bubbles per unit thickness of the foam layer (A) is 3 to 50 / mm, preferably 4 to 50 / mm, and more preferably about 5 to 50 / mm. When the average number of bubbles is within this range, the heat retaining property, heat insulating property and appearance are good, and the waist and impact resistance of the sheet are high. The number of bubbles per unit thickness is counted from the cross-sectional photograph in the thickness direction of the foam layer by counting the number of bubbles crossing the line in the thickness direction (line perpendicular to the surface direction of the foam layer). It can be obtained by converting to.

  The bubbles in the foam layer (A) are preferably composed mainly of closed cells, and the ratio of closed cells (closed cell rate) is preferably 50% or more (for example, 50 to 100%) of all bubbles, preferably Is 70% or more (70 to 100%), more preferably about 80 to 100% (especially 85 to 100%). When the closed cell ratio is in this range, the moldability is excellent and the effect of weight reduction is enhanced. If the closed cell ratio is too small, it is easily broken by molding, the appearance of the molded product is lowered, and the effect of weight reduction is reduced.

  The expansion ratio of the foam layer (A) is preferably a low expansion ratio, and can be selected from a range of about 1 to 3 times, for example, 1.05 to 2 times, preferably 1.1 to 1.8 times. More preferably, it is about 1.2 to 1.5 times.

[Non-foamed layer (B)]
The non-foamed layer (B) comprises a styrene resin (b1), an olefin resin (b2) having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210, and an aromatic vinyl-diene copolymer. It is comprised with the resin composition containing (b3). In the present invention, by combining the foamed layer (A) having a specific composition and such a non-foamed layer (B), the mechanical strength such as rigidity and surface gloss can be improved while reducing the weight. it can.

(b1) Styrene Resin As the styrene resin (b1), the same styrene resin exemplified in the section of the styrene resin (a1) can be exemplified. The styrenic resin (b1) is preferably the same styrenic resin as the styrenic resin (a1) or the same styrenic resin from the viewpoint of adhesion between layers.

  The proportion of the rubber-modified styrenic resin in the non-foamed layer (B) is, for example, 5% by weight or less (0 to 5% by weight), preferably 3% by weight or less, more preferably from the viewpoint of not reducing the gloss of the surface. May be 2% by weight or less.

  The proportion of the styrene resin (b1) in the non-foamed layer (B) is usually about the same as the proportion of the styrene resin (a1) in the foamed layer (A), but heat resistance, oil resistance, resistance to cracking From the viewpoint of mechanical properties such as the thickness, it is preferably less than the proportion of the olefin resin (a2) in the foamed layer (A).

(b2) Olefin Resin As the olefin resin (b2), the same olefin resin exemplified in the section of the olefin resin (a2) can be exemplified. The olefin resin (b1) is preferably the same olefin resin as the olefin resin (a2) or the same olefin resin from the viewpoint of adhesion between layers.

  In the olefin resin (b2), among polypropylene resins, a propylene-α-olefin copolymer, particularly a propylene-ethylene block or a random copolymer is more preferable than a propylene homopolymer in terms of gloss. preferable. In the propylene-α-olefin copolymer, the ratio (molar ratio) of propylene and α-olefin is propylene / α-olefin = 60/40 to 99.9 / 0.1, preferably 70/30 to 99.99. The ratio is about 5 / 0.5, more preferably about 80/20 to 99/1 (particularly 90/10 to 97/3).

  The proportion of the olefin resin (b2) in the non-foamed layer (B) is usually about the same as the proportion of the olefin resin (a2) in the foamed layer (A), but heat resistance, oil resistance, resistance to cracking From the standpoint of mechanical properties such as the thickness, it is preferably larger than the proportion of the olefin resin (a2) in the foamed layer (A).

  The ratio (weight ratio) between the styrene resin (b1) and the olefin resin (b2) is the same as the ratio (weight ratio) between the styrene resin (a1) and the olefin resin (a2).

(b3) Aromatic vinyl-diene copolymer As the aromatic vinyl-diene copolymer (b3), the same aromatic vinyl exemplified in the section of the aromatic vinyl-diene copolymer (a3) is used. -A diene type copolymer can be illustrated. The aromatic vinyl-diene copolymer (a1) is the same aromatic vinyl-diene copolymer as the aromatic vinyl-diene copolymer (a3) or the same type of fragrance from the viewpoint of adhesion between layers. It is preferable to use an aromatic vinyl-diene copolymer.

  The ratio of the aromatic vinyl-diene copolymer (b3) in the non-foamed layer (B) is usually the same as the ratio of the aromatic vinyl-diene copolymer (a3) in the foamed layer (A). However, from the viewpoint of mechanical properties such as heat resistance, oil resistance and resistance to cracking, it is preferable that the ratio be higher than the proportion of the olefin resin (a2) in the foamed layer (A).

  The ratio of the aromatic vinyl-diene copolymer (b3) to the total amount of the styrene resin (b1) and the olefin resin (b2) is the same as that of the aromatic vinyl-diene copolymer (a3).

  Similarly to the foamed layer (A), a pigment component or a conventional additive may be added to the non-foamed layer (B). As the pigment component in the non-foamed layer, for example, a black pigment such as carbon black is widely used. However, from the viewpoint of gloss, it is preferable that the surface layer does not contain the pigment component.

  The thickness of the non-foamed layer (B) is, for example, about 10 to 150 μm, preferably 15 to 130 μm, and more preferably about 20 to 100 μm.

[Laminated sheet]
In the laminated sheet of the present invention, the non-foamed layer (B) is formed on at least one surface of the foamed layer (A). By forming the non-foamed layer, the productivity, appearance, and oil resistance of the sheet are improved, and both mechanical strength and light weight can be achieved. From these points, it is particularly preferable that the non-foamed layer (B) is formed on both surfaces of the foamed layer (A).

  The specific gravity of the laminated sheet is, for example, about 0.4 to 0.9, preferably about 0.4 to 0.8, and more preferably about 0.4 to 0.6. When the specific gravity is within this range, it is possible to impart practically necessary waist to the sheet and a molded product formed from the sheet with a small amount of resin, which is effective in reducing the weight. Furthermore, it is excellent in heat retention, heat insulation and appearance, improves the stackability of molded products such as containers, and is not bulky.

  The thickness of the laminated sheet is, for example, about 0.3 to 2 mm, preferably about 0.3 to 1.5 mm, and more preferably about 0.4 to 1.2 mm. If the thickness of the laminated sheet is too small, it is easy to tear in the flow direction of the sheet, and if it is too large, the stackability of the molded product is not sufficient and the bulkiness is large. When the thickness of the sheet is in the above range, the waist and heat insulation of the sheet are high, and the appearance is also excellent.

  The ratio of the foamed layer (A) in the laminated sheet is, for example, 40 to 90% by weight, preferably 45 to 85% by weight, more preferably 50 to 85% by weight (particularly 60 to 85%) with respect to the total weight of the laminated sheet. 80% by weight). If the ratio of the foamed layer (A) is too small, the effect of reducing the weight is small, and if it is too large, it is easily broken when molded and the appearance of the surface is lowered.

  When the non-foamed layer (B) is on both sides of the foamed layer (A), the ratio of the upper layer thickness to the lower layer thickness of the non-foamed layer is the former / the latter = 5/1 to 1/5, preferably 3 / The thickness is about 1/3, more preferably about 2/1 to 1/2, and usually the upper layer and the lower layer have the same thickness.

  The ratio of the thickness (DA) of the foam layer (A) and the total thickness (DB) of the non-foam layer (B) is DA / DB = 100/1 to 1/1, preferably 50/1 to 2/1. More preferably, it is about 30/1 to 3/1 (particularly 20/1 to 5/1).

  The surface gloss of the laminated sheet is, for example, 10% or more (for example, 10 to 95%), preferably 12% or more (for example, 10 to 90%) in a method according to JIS K 7105 (incident angle 60 °). More preferably, it is about 15% or more (for example, 15 to 85%). When the surface gloss is in the above range, even when the surface gloss is extended by molding, the surface appearance is not deteriorated, and a high-quality feeling of the molded product can be produced.

  The centerline average roughness Ra of the laminated sheet is, for example, 0.1 to 1 μm, preferably 0.1 to 0.8 μm, and more preferably about 0.1 to 0.7 μm in the method based on JIS B 0601. is there.

  A resin layer may be further formed on at least one surface of the laminated sheet. The resin layer (C) may be formed on the foam layer (A), but is formed on the non-foam layer (B), and the non-foam layer (B) is formed on both sides of the foam layer (A). If it is, the resin layer (C) is also formed on both sides.

  As the resin layer (C), various thermoplastic resins and thermosetting resins can be used, but from the viewpoint of adhesiveness with the laminated sheet, styrene-based resin or olefin-based resin, particularly those of the same system as the laminated sheet. Styrenic resins or olefinic resins are preferred. Further, the resin layer may be a layer imparted with various functions depending on the application. For example, a gas barrier resin (for example, vinyl alcohol polymer, vinylidene chloride polymer, cyclic olefin resin, etc.) It may be a gas barrier layer formed by Furthermore, the resin layer may be printed. In this case, the resin layer may be adhered to the laminated sheet with a binder contained in the printing ink.

  The thickness of the resin layer (C) is, for example, about 5 to 100 μm, preferably about 10 to 50 μm, and more preferably about 20 to 40 μm.

[Production method of laminated sheet]
The foamed layer (A) and the non-foamed layer (B) constituting the laminated sheet are not particularly limited, and are formed by mixing the components of each layer using a tumbler, a super mixer, etc., and then directly feeding them to the sheet extruder. Alternatively, it may be formed by melting and kneading with a roll, a Banbury mixer, a kneader, a single-screw or twin-screw extruder to form a pellet, and then feeding to a sheet extruder. Sheet molding methods include, for example, extrusion methods such as an extrusion method [die (flat shape, T shape (T die), cylindrical shape (circular die), etc.) method, inflation method, etc.], a tenter method, and a tube method. And a stretching method using an inflation method. The sheet may be unstretched or stretched (uniaxial stretching, biaxial stretching, etc.).

  As a foaming method for the foam layer (A), a conventional method, for example, a method using a reaction product gas, a method using a foaming agent, or the like can be used. Among these methods, a foaming agent is used. The extrusion foaming method is preferred.

  The foaming agent includes a volatile foaming agent and a degradable foaming agent. Examples of volatile foaming agents include gases [carbon dioxide (carbon dioxide), hydrocarbons (propane, butane, pentane, etc.), methyl ether, trifluorochloromethane, nitrogen, etc.], volatile liquids [water, ethers, etc.] (Ethyl ether, petroleum ether), acetone, hydrocarbon (liquid propane, liquid butane, hexane), benzene] and the like. These volatile blowing agents can be used alone or in combination of two or more.

  Examples of the decomposable foaming agent include organic acids or salts thereof (citric acid, sodium citrate, etc.), azo compounds (2,2′-azobisisobutyronitrile, azohexahydrobenzonitrile, azodicarboxylic acid amide, Diazoaminobenzene, etc.), sulfonyl hydrazide compounds [benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, 4,4′-oxybis (benzenesulfonyl hydrazide), etc.], nitroso compounds (N, N′-dinitropentamethylenetetramine, N, N Organic compounds such as' -dinitroso-N, N'-dimethylterephthalamide) and inorganic compounds such as sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate. These decomposable foaming agents can be used alone or in combination of two or more.

  The ratio of the blowing agent is 0.01 to 20 parts by weight, preferably 0. 0 to 100 parts by weight with respect to 100 parts by weight of the resin composition containing the styrene resin (a1), the olefin resin (a2) and the compatibilizer (a3). It is about 1 to 10 parts by weight, more preferably about 0.5 to 5 parts by weight.

  Laminated sheets may be prepared by laminating each obtained sheet by methods such as heat lamination and dry lamination, but the resin composition for each layer is used using a general-purpose die with a feed block or a multi-manifold die. Then, it is preferable to prepare by a method of co-extrusion. Extruder for the resin composition (or pellets) constituting the foam layer (A), the resin composition constituting the non-foam layer (B), and the resin composition constituting the resin layer (C) as required , Melted and stirred, and the resin composition layers are joined and laminated in a die, and extruded from the die to obtain a laminated sheet. In the coextrusion method, a thin surface layer can be obtained and the mass productivity is excellent. Among these co-extrusion methods, a co-extrusion T-die molding method, a co-extrusion circular die molding method, and a co-extrusion hollow molding method can be used, and a thin sheet can be obtained with a low foaming rate. Molding is preferred. The extrusion temperature is about 120 to 300 ° C, preferably about 150 to 280 ° C.

  In the lamination method, an adhesive is not necessarily required. The resin layer (C) is usually bonded by a laminating method.

[Secondary molding method and secondary molded product]
The laminated sheet obtained in this way is excellent in formability, so it is pressure forming (extrusion pressure forming, hot plate pressure forming, vacuum pressure forming, etc.), free blow forming, vacuum forming, bending, match mold forming, heat Secondary molding can be easily performed by conventional thermoforming such as plate molding.

  In the thermoforming step, the heated sheet is formed by pressurization or depressurization. For example, in the case of pressure forming, the heated sheet is pressed against a mold by means of compressed air. In the case of vacuum forming, by forming a vacuum between the mold and the heated sheet, the heated sheet is drawn into the mold side and molded. The mold is provided with small holes and slits for drawing air. Moreover, after heating and secondary foaming, a method of forming a desired thickness and shape by a matched mold method using both male and female molds can be preferably employed.

  The laminated sheet of the present invention is lightweight and has high mechanical strength, and is excellent in heat resistance, appearance, oil resistance, etc., so it can be used in various applications, for example, as a secondary molded product such as a container. can do. Containers include liquid filling containers such as beverages, food containers (such as sugar beet containers and lunch box containers), chemical containers, ovens and microwave oven containers, and hot water pouring containers (for example, instant food containers) Etc.), containers for foods containing fats and oils (for example, foods containing fats and oils such as dumplings, foods such as fish and shellfish from which fats and oils exude), containers used for heat sterilization, non-heated containers, etc. be able to. The container is used to mean that it may include a lid body as well as a container body having a recess for accommodating a container, and if it is a container for sugar beet or a lunch box, it means that it includes a tray and a lid. is there. The lid body may be removable as long as it can be opened and closed with respect to the container body, and may be coupled to the hinge system.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the content of the symbol of each component used by the Example and the comparative example, and the evaluation method of each evaluation item are as follows.

[Contents of abbreviations for each component]
(Styrene resin)
GPPS: Polystyrene (trade name “# 30” manufactured by Toyo Styrene Co., Ltd.)
HIPS: High impact polystyrene (trade name “E640N” manufactured by Toyo Styrene Co., Ltd.).

(Olefin resin)
PP-1: Polypropylene resin (Mitsui / Sumitomo Polyolefin Co., Ltd., trade name “F812A”, MFR = 1.7)
PP-2: Polypropylene resin (manufactured by Sun Allomer Co., Ltd., trade name “PB270A”, MFR = 0.7)
PP-3: Polypropylene resin (Mitsui / Sumitomo Polyolefin Co., Ltd., trade name “F707V”, MFR = 6.5)
PP-4: Polypropylene resin (manufactured by Mitsui Sumitomo Polyolefin Co., Ltd., trade name “J706WB”, MFR = 24).

(Aromatic vinyl-diene copolymer)
SBS: Styrene-butadiene block copolymer resin (manufactured by JSR Corporation, trade name “TR2003”).

(Other additives)
Effervescent agent: Mixture of sodium bicarbonate and monosodium citrate (trade name “Cermic 623” manufactured by Sankyo Kasei Co., Ltd.)
White MB: A mixture of polystyrene, a titanium oxide-containing pigment, and a dispersant (Polycol Kogyo Co., Ltd., trade name “ESH-W-18888”).

[Evaluation item]
Each laminated sheet and cup container obtained in Examples and Comparative Examples were evaluated by the following items and methods.

(1) Weight ratio of foam layer Photographs were taken with an optical microscope of five sections in the thickness direction of arbitrary portions in a direction orthogonal to the sheet flow of the laminated sheet. Using these photographs, the thickness of the foamed part and the non-foamed part was determined, the weight ratio was calculated in consideration of the specific gravity of the resin composition of each layer, and the average value was determined.

(2) Average number of bubbles in foam layer The number of bubbles was calculated using the photograph in the evaluation item (1), and the average value was obtained as the number of bubbles per 1 mm of the foam layer.

(3) Foaming state of foam layer Using the photograph of the evaluation item (1), the following criteria were used for evaluation.

◎: More than 85% of the bubbles are independent ○: More than 70% and less than 85% of the bubbles are independent △: More than 50% and less than 70% of the bubbles are independent ×: Less than 50% of the bubbles being independent.

(4) Formability of container The portion where the bottom surface and the side surface of the cup container are in contact with each other, the tearing of the side surface, and the surface state were visually observed and evaluated according to the following criteria.

◎: No tearing, uniform thickness, and smooth surface obtained ○: No tearing, uniform thickness, but some Japanese paper-like irregularities on the surface △: No tearing, thickness Was uneven, and there was a Japanese paper-like unevenness on the surface. X: There was a tear, and the unevenness on the surface was also remarkable.

(5) Appearance of container The appearance of the cup container was visually observed and evaluated according to the following criteria.

◎: The surface is uniform and glossy and high-class feeling ○: The surface is uniform but not glossy △: The surface is rough and not glossy ×: The surface is severely rough and the texture is rough.

(6) Heat resistance by microwave oven 100 g of commercially available salad oil (manufactured by Nisshin Flour Milling Co., Ltd.) was placed in a cup container and heated in a 500 W microwave oven for 5 minutes. The degree of deformation of the container after heating was visually observed and evaluated according to the following criteria.

A: There is no deformation, and there is no dissolution mark or oil penetration on the surface. ○: There is a slight deformation, but there is no dissolution mark or oil penetration on the surface. Δ: There is a slight deformation, and there is a dissolution mark or oil on the surface. X: Deformation is large, and dissolution marks and oil penetration are observed on the surface.

(7) Oil resistance 100 g of commercially available salad oil (manufactured by Nissin Flour Milling Co., Ltd.) was placed in a cup container and left in a constant temperature bath at 40 ° C. for 5 days. Then, oil was taken out and the state of the container was visually observed and evaluated according to the following criteria.

◎: No abnormality (occurrence of oil leakage, coloring, cracking, cracking) ○: Coloring is slightly observed, but no oil leakage, cracking, cracking is observed △: Oil leakage and coloring are slightly observed, no cracking, cracking : Oil leakage and coloring are remarkable, and cracks and cracks are also generated.

(8) Weight reduction degree of container As a comparison for confirming the effect of reducing the weight of the foamed laminated sheet, it is the same as in Examples and Comparative Examples except that no foaming agent is added to the foam layer. Five types of non-foamed laminated sheets of 400, 350 and 300 g / m ² were obtained. The sheet thus obtained was molded into a cup container (opening diameter 90 mm, bottom diameter 80 mm, height 45 mm) using a single vacuum forming machine (manufactured by Asano Laboratories). Using a cup container in which a foamed laminated sheet (340 g / m ² ) and a non-foamed laminated sheet were molded, placed on a horizontal surface with the container opening facing upward, a constant of 10 mm / min using a circular jig with a diameter of 150 mm from above The displacement and load at this time were measured with Tensilon (manufactured by Orientec Co., Ltd.), and the inclination (kgf (N) / displacement mm) was measured. The weight reduction degree (%) was calculated | required from the weight per unit area of the non-foaming laminated container which shows the data equivalent to a foaming laminated container.

(9) Elongation at break In accordance with JIS K 7127, a sheet punched into a No. 2 type test piece along the sheet flow direction (MD direction) was subjected to a tensile test with Tensilon (Orientec Co., Ltd.) And the displacement L (mm) until the tensile fracture occurred was measured. Based on the result, elongation at break was determined as (L / distance between grippers) × 100 = (100 × L) / 80.

Examples 1-9 and Comparative Examples 1-4
As a material for the foam layer, a foaming agent is added to and blended with the resin composition comprising the components (a1) to (a3) shown in Table 1, and a feed block type multilayer extruder (diameter Φ65 mm, diameter Φ50 mm) To a Φ65 mm extruder. Furthermore, as the material for the non-foamed layer, a resin composition comprising the components (b1) to (b3) having the composition shown in Table 1 was blended and supplied to a Φ50 mm extruder. Melt-knead in each extruder, extrude into a sheet form from a T-die, rapidly cool the sheet surface to a temperature below the glass transition temperature of the styrene resin used (about 100 ° C), and adjust the take-up speed Thus, a foamed laminated sheet of 340 g / m ² per unit area was obtained. In addition, the layer structure had the non-foamed layer laminated | stacked on both surfaces of the foamed layer. Moreover, the weight ratio with respect to the whole sheet | seat of a foam layer adjusted with the screw rotation speed of each extruder. Each foamed laminate sheet thus obtained was molded into a cup container (opening diameter 90 mm, bottom diameter 80 mm, height 45 mm) using a single vacuum forming machine (manufactured by Asano Laboratory Co., Ltd.). Table 1 shows the evaluation results for the obtained sheets and containers.

Example 10
On one side of the foamed laminated sheet obtained in Example 2, a printed polypropylene film (product name “P1111”, thickness 25 μm, manufactured by Toyobo Co., Ltd.) was laminated using a dielectric heating roll type laminating apparatus, A foamed laminated sheet laminated with a printing film was obtained. Each foamed laminate sheet thus obtained was molded into a cup container (opening diameter 90 mm, bottom diameter 80 mm, height 45 mm) using a single vacuum forming machine (manufactured by Asano Laboratory Co., Ltd.). Table 1 shows the evaluation results for the obtained sheets and containers.

  The laminated sheets of Examples 1 to 10 were excellent in appearance, heat resistance, oil resistance, and container moldability, and the degree of weight reduction was large. On the other hand, the sheets of Comparative Examples 1 to 3 have an insufficient appearance and a low degree of weight reduction. Further, the sheet of Comparative Example 4 has insufficient heat resistance and oil resistance.

Examples 11-15 and Comparative Examples 5-8
A foamed laminated sheet and a container were obtained in the same manner as in Example 1 except that the components shown in Table 2 were used as the foam layer material and the non-foam layer material. In the sheets of Examples 11 to 13, the expansion ratio is changed by changing the amount of the foaming agent, and the same applies to the sheets of Comparative Examples 5 to 7. Table 2 shows the evaluation results for the obtained sheets and containers.

  In addition, the cross-sectional photograph of the laminated sheet obtained in Examples 11-15 and Comparative Examples 5-8 is shown in FIGS. As is clear from the photographs of FIGS. 1 and 2, round closed cells can be observed in the laminated sheets of Examples 11 and 12. As is clear from the photograph in FIG. 3, in the laminated sheet of Example 13, round bubbles with continuous air permeability can be observed. As is apparent from the photographs of FIGS. 4 and 5, in the laminated sheets of Examples 14 and 15, round air bubbles with continuous air permeability can be observed. As is apparent from the photographs in FIGS. 6 and 7, irregular bubbles can be observed in the laminated sheets of Comparative Examples 5 and 6. As is clear from FIG. 8, in the laminated sheet of Comparative Example 7, bubbles with continuous air permeability can be observed. As is clear from FIG. 9, in the laminated sheet of Comparative Example 8, fine and continuous air bubbles can be observed.

  Furthermore, based on the result of Table 2, about the sheet | seat of Examples 11-13 and Comparative Examples 5-8, the relationship between a foaming ratio and various characteristics is shown as a graph. In the graph, for Examples 11 to 13, approximate lines are created based on each data.

  FIG. 10 is a graph showing the relationship between the expansion ratio and the surface gloss. As is apparent from the graph of FIG. 10, the laminated sheet of the example using polypropylene with a low melt flow rate shows high glossiness regardless of the expansion ratio.

  FIG. 11 is a graph showing the relationship between the expansion ratio and the appearance of the container. As is clear from the graph of FIG. 11, the laminated sheet of the example shows an excellent appearance as compared with the laminated sheet of the comparative example. In addition, about the external appearance of a container, the inner surface of an container, an outer surface, and the external appearance seen through are each represented by a score, and it is a value when it is set as a perfect score of 12 points.

  FIG. 12 is a graph showing the relationship between the expansion ratio and the closed cell ratio. As apparent from the graph of FIG. 12, the laminated sheet of the example has a higher closed cell ratio than the laminated sheet of the comparative example.

  FIG. 13 is a graph showing the relationship between the expansion ratio and the weight reduction degree of the container. As can be seen from the graph of FIG. 13, the laminated sheet of the example is reduced in weight regardless of the expansion ratio, and is superior in weight to the laminated sheet of the comparative example.

  FIG. 14 is a graph showing the relationship between the expansion ratio and the elongation at break (MD direction). As apparent from the graph of FIG. 14, the laminated sheet of the example has a higher elongation at break than the laminated sheet of the comparative example.

1 is a photomicrograph (magnification 80 times) showing a cross section of the laminated sheet obtained in Example 11. FIG. FIG. 2 is a photomicrograph (80 ×) showing a cross section of the laminated sheet obtained in Example 12. FIG. 3 is a micrograph (80 ×) showing a cross section of the laminated sheet obtained in Example 13. FIG. 4 is a micrograph (80 ×) showing a cross section of the laminated sheet obtained in Example 14. FIG. 5 is a photomicrograph (80 ×) showing a cross section of the laminated sheet obtained in Example 15. 6 is a photomicrograph (80 ×) showing a cross section of the laminated sheet obtained in Comparative Example 5. FIG. FIG. 7 is a photomicrograph (80 ×) showing a cross section of the laminated sheet obtained in Comparative Example 6. FIG. 8 is a photomicrograph (80 ×) showing a cross section of the laminated sheet obtained in Comparative Example 7. FIG. 9 is a micrograph (80 ×) showing a cross section of the laminated sheet obtained in Comparative Example 8. FIG. 10 is a graph showing the relationship between the expansion ratio and surface gloss of the laminated sheets obtained in Examples 11 to 13 and Comparative Examples 5 to 8. FIG. 11 is a graph showing the relationship between the expansion ratio of the laminated sheets obtained in Examples 11 to 13 and Comparative Examples 5 to 8 and the appearance of the container. FIG. 12 is a graph showing the relationship between the expansion ratio and the closed cell ratio of the laminated sheets obtained in Examples 11 to 13 and Comparative Examples 5 to 8. FIG. 13 is a graph showing the relationship between the expansion ratio of the laminated sheets obtained in Examples 11 to 13 and Comparative Examples 5 to 8 and the weight reduction degree of the container. FIG. 14 is a graph showing the relationship between the expansion ratio and elongation at break (MD direction) of the laminated sheets obtained in Examples 11 to 13 and Comparative Examples 5 to 8.

Claims (13)

  A resin composition comprising a styrene resin (a1), an olefin resin (a2) having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210, and an aromatic vinyl-diene copolymer (a3) Styrene resin (b1), olefin resin (b2) having a melt flow rate in accordance with JIS K 7210 of 0.4 or more and less than 3, and at least one surface of the foam layer (A) composed of A laminated sheet on which a non-foamed layer (B) composed of a resin composition containing an aromatic vinyl-diene copolymer (b3) is formed.   In the foam layer (A) and the non-foam layer (B), the styrene resin (a1) and / or (b1) contains at least a non-rubber-containing styrene resin, and the olefin resin (a2) and / or (b2) The sheet according to claim 1, which is a polypropylene resin.   The styrene resin (b1) is composed of a non-rubber-containing styrene resin and a rubber-modified styrene resin, and the ratio of the rubber-modified styrene resin in the non-foamed layer (B) is 5% by weight or less. Item 1. The sheet according to Item 1.   In the foam layer (A), the ratio (weight ratio) between the styrene resin (a1) and the olefin resin (a2) is styrene resin (a1) / olefin resin (a2) = 30/70 to 99/1. The ratio of the aromatic vinyl-diene copolymer (a3) is 0.1 to 30 parts by weight with respect to 100 parts by weight of the total of the styrene resin (a1) and the olefin resin (a2). In addition, the proportions of the olefin resin (b2) and the aromatic vinyl-diene copolymer (b3) in the non-foamed layer (B) are the olefin resin (a2) and aromatic in the foamed layer (A), respectively. The sheet according to claim 1, wherein the ratio is equal to or greater than the ratio of the group vinyl-diene copolymer (a3).   The sheet according to claim 1, wherein the expansion ratio of the foam layer (A) is 1.05 to 2 times, and the ratio of the foam layer (A) is 40 to 90 wt% with respect to the entire sheet.   The sheet according to claim 1, wherein the surface gloss at an incident angle of 60 ° in accordance with JIS K 7105 is 10% or more, and the center line average roughness Ra in accordance with JIS B 0601 is 0.1 to 1 µm.   The sheet according to claim 1, wherein the non-foamed layer (B) is formed on both sides of the foamed layer (A).   A laminated sheet in which a resin layer (C) is further formed on at least one surface of the sheet according to claim 1.   The sheet according to claim 8, wherein the resin layer (C) is composed of a styrene resin or an olefin resin that may be printed.   On both surfaces of a foam layer (A) composed of a styrene resin, a polypropylene resin having a melt flow rate of 0.5 to 2 in accordance with JIS K 7210, and a styrene-butadiene block copolymer A non-foamed layer (B) composed of a resin composition comprising a styrene resin, a polypropylene resin having a melt flow rate of 0.5 to 2 in accordance with JIS K 7210, and a styrene-butadiene block copolymer In the foamed layer (A), the ratio (weight ratio) of the styrene resin and the polypropylene resin is the former / the latter = 50/50 to 90/10, and the styrene-butadiene block While the proportion of the copolymer is 0.5 to 20 parts by weight with respect to a total of 100 parts by weight of the styrene resin and the polypropylene resin, Laminated sheet ratio of the rubber-modified styrene resin in the foam layer (B) is 3 wt% or less.   A resin composition comprising a styrene resin (a1), an olefin resin (a2) having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210, and an aromatic vinyl-diene copolymer (a3) Styrene resin (b1), olefin resin (b2) having a melt flow rate in accordance with JIS K 7210 of 0.4 or more and less than 3, and at least one surface of the foam layer (A) composed of For producing a laminated sheet for forming a non-foamed layer (B) composed of a resin composition containing an aromatic vinyl-diene copolymer (b3).   A container formed of the sheet according to claim 1.   On at least one surface of the foam layer (A) composed of a resin composition containing a styrene resin, an olefin resin, and an aromatic vinyl-diene copolymer, a styrene resin, an olefin resin, and an aromatic A method for improving the mechanical strength and surface gloss of a laminated sheet on which a non-foamed layer (B) composed of a resin composition containing a vinyl-diene copolymer is formed, the foamed layer (A) and non-foamed layer A method for improving the mechanical strength and surface gloss of a laminated sheet using an olefin resin having a melt flow rate of 0.4 or more and less than 3 according to JIS K 7210 as the olefin resin constituting the foamed layer (B) .