JPH09156048A - Styrene resin-laminated biaxially stretched sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrene resin-laminated biaxially stretched sheet with superior resistance against oils, plasticizers and folding and also high transparency. SOLUTION: This styrene resin-laminated biaxially stretched sheet consists of (A) styrene resin as a base material layer and (B) an oil-resistant resin layer of a resin composition containing 5-40 pts.wt. of transparent and impact-resistant styrene resin blended for 100 pts.wt. of a mixed resin of 10-40wt.% of polyphenylene ether resin and 90-60wt.% of styrene resin, laminated on at least, one of the faces of the resin (A). In addition, this sheet has both lengthwise and crosswise orientation relaxing stresses of 3-8kg/cm<2> , an antifolding strength of at least, 200 times and an oil resistance of 24 hours or more.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a styrene resin laminated biaxially stretched sheet. More specifically, transparency,
It retains the original properties of styrenic resin stretched sheets such as rigidity and formability, and has excellent oil resistance, plasticizer resistance, recyclability, and folding resistance, and can be used as wrap packaging for storing foods containing oil. The present invention relates to a styrene-based resin laminated biaxially stretched sheet which is inexpensive and suitable as a molding material for a container to be provided.

[0002]

2. Description of the Related Art Stretched styrene resin sheets, especially biaxially stretched sheets made of styrene resin containing polystyrene for general use as a main component, show good transparency, are strong, and have excellent moldability. Since a container or the like can be easily molded by a thermoforming method such as a molding method or a pressure molding method, it is mainly used in large quantities for the production of lightweight containers for food packaging.

Up to now, heat resistance and the like have been improved in order to meet applications such as cooking in a microwave oven and direct contact with boiling water. However, at present, there is still a problem to be improved because of packaging a wide variety of foods. One of them is a problem due to oil resistance. Many foods to be packaged contain fats and oils for synthetic foods such as MCT (medium chain fatty acid triglyceride) for the purpose of providing luster and the like. If it is a normal styrene resin stretched sheet,
Such synthetic food oils and fats have a drawback that they are attacked within a short time, the container is whitened, and the container is cracked and cracked.

When a stretchable film is used to overlap the entire container containing foods, a soft polyvinyl chloride film is used as the stretch film, because of the plasticizer and other additives contained in the film, especially the flange of the container. There is a defect that the part is attacked and deteriorated, and it becomes very easy to crack. As a method for imparting oil resistance to a stretched styrene resin sheet, for example, JP-A-54-2 is used.
No. 9381, a method using a specific high-impact polystyrene of graft type, for example, JP-A-5-31858.
No. 0, a method using a styrene-methacrylic acid binary copolymer, and the like have been proposed, but all of them are easily attacked by synthetic edible fats and oils and cannot be said to exhibit very sufficient oil resistance. Further, as a method of using a resin having good oil resistance, for example, JP-A-4-145155, a substantially amorphous specific polyester-based polymer and a specific copolymer composed of a styrene-based derivative or the like can be used. A method of using a resin composition prepared by blending in a specific ratio, for example, JP-A-6-8
No. 7191, a method of laminating a propylene resin layer on a styrene resin layer, and the like have been proposed.

Although oil resistance and plasticizer resistance are improved by these methods, the trim, scrap, or skeleton (bone) generated when a molded product is punched out from the laminated sheet is reused. I can't. This is because the above polyesters, polypropylenes, etc. have extremely poor compatibility with styrene resins, and the physical properties are significantly deteriorated. Even if you try to reuse it by using a compatibilizer,
In addition to being costly, the sheet becomes opaque and loses its value as a food container.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art by maintaining the various properties inherent to a stretched styrene resin sheet such as transparency, rigidity and moldability, and Reuse of trims, scraps, and skeletons (bones) generated when punching a molded product from a laminated sheet, which is not attacked by oil components in food or plasticizer components in stretch film It is an object of the present invention to provide an inexpensive styrene-based resin laminated biaxially stretched sheet capable of producing a molded product such as a food pack having sufficient strength.

[0007]

However, in the present invention, the following means are provided to solve the above problems. That is, according to the present invention, the styrene resin (a) is used as the base material layer (A), and the oil resistant resin layer (B) is formed on at least one surface of the base material layer (A). In the axially stretched sheet, the base material layer (A) has a thickness of 80 to 500 μm, and the oil resistant resin layer (B) is 10 to 40% by weight of the polyphenylene ether resin (b1).
And a resin composition in which 5 to 40 parts by weight of a transparent impact resistant styrene resin (b3) is mixed with 100 parts by weight of a resin composition consisting of 90 to 60% by weight of the styrene resin (b2). , Its thickness is 10 to 100 μm, and the orientation relaxation stress of the laminated sheet is biaxially stretched so as to be ³ to 8 kg / cm ^{2 in} both the flow direction and the direction perpendicular thereto, and the folding strength is 200 times or more. And an oil-resistant styrene-based resin laminated biaxially stretched sheet having an oil resistance of more than 24 hours.

Hereinafter, the present invention will be described in detail. The styrene resin biaxially stretched laminated sheet of the present invention has a base material layer (A) made of a styrene resin (a). The styrene resin (a) is not particularly limited, and various conventionally known styrene resins can be appropriately selected and used. Typical examples are styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, dimethylstyrene, α-methylstyrene, p-chlorostyrene,
Homopolymers of styrene such as 2,4-dichlorostyrene and its derivatives, or copolymers, styrene or at least one of the above styrene derivatives and 2 other monomers copolymerizable with these polymers. Examples include terpolymers, terpolymers, and quaternary or higher copolymers. Further, a mixed composition in which two or more kinds of these polymers are mixed is included.

Other monomers that can be copolymerized include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate; methyl acrylate, ethyl acrylate, propyl acrylate, Acrylic esters such as butyl acrylate; unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; unsaturated carboxylic acids such as acrylic acid and methacrylic acid Is mentioned.

Among these styrene resins (a),
In particular, general-purpose polystyrene (styrene homopolymer) is most preferable because it has excellent transparency, is easily available, and is inexpensive. The base material layer (A) may contain a so-called recycled material such as an ear trim generated during sheet molding, sheet waste, or a skeleton generated after punching a molded product from the sheet in an amount of 10 to 50 weight. % Is preferred. At this time, if the concentration of the polyphenylene ether-based resin (b1) in the base material layer (A) is higher than 5%, the strength of the entire laminated sheet decreases, which is not preferable.

The recycled material is usually crushed into small pieces, then blended with a virgin raw material and used for sheeting. The thickness of the base material layer (A) is 80 to 500 μm,
It is preferably 100 to 300 μm. When the thickness is less than 80 μm, the rigidity of the entire laminated sheet when molded is lowered, and as a result, the load on the oil resistant resin layer (B) becomes large, and desired oil resistance and plasticizer resistance cannot be obtained.

The styrene resin biaxially stretched laminated sheet of the present invention comprises an oil resistant resin layer (B) formed on at least one surface of a base material layer (A), and the oil resistant resin layer (B) comprises It imparts oil resistance, plasticizer resistance, and folding resistance to a styrene resin laminated biaxially stretched sheet. The oil resistant resin layer (B) includes a polyphenylene ether resin (b1) and a styrene resin (b2), and a transparent impact resistant styrene resin (b).
3) is mixed with a resin in a specific ratio.

Examples of the polyphenylene ether resin (b1) include those represented by the following general formula (I).

[0014]

Embedded image [In the formula, R ₁ and R ₂ are each independently selected from an alkyl group, a substituted alkyl group, a halogen atom, a hydrogen atom, an aryl group, a substituted aryl group, and the like, n is an integer representing the degree of polymerization, X ₁ , X ₂ is a free terminal group in the phenylene ether polymer. ]

Specific examples of the polyphenylene ether resin represented by the above general formula (〓) include poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,6).
-Diethyl-1,4-phenylene) ether, poly (2,6-dipropyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ether, poly (2-methyl) -6-propyl-1,
4-phenylene) ether, poly (2-ethyl-6-propyl-1,4-phenylene) ether, poly (2-methyl-6-bromo-1,4-phenylene) ether, poly (2-methyl-6-) Chlor-1,4-phenylene) ether, and the like.

In the present invention, as the polyphenylene ether-based resin (b1), other copolymerizable monomers may be used as long as they mainly have the chemical structure represented by the above general formula (〓). . Specific examples of such copolymers include copolymers of 2,6-di-substituted phenol and 2,4-di-substituted phenol, 2,6-di-substituted phenol and 2,
Copolymers with 3,6-tri-substituted phenol, copolymers with 2,6-dimethylphenol and 2-substituted phenol, 3-substituted phenol or 4-substituted phenol, etc. Is mentioned.

Of these, poly (2,6-dimethyl-1,4-phenylene) ether is particularly preferable. The intrinsic viscosity of the polymer (chloroform, measured at 25 ° C.) is preferably in the range of 0.2 to 1 dl / g, and 0.3 to
The use of one having a range of 0.7 dl / g is more preferable because a styrene resin laminated biaxially stretched sheet excellent in mechanical strength and moldability can be obtained.

The styrene resin (b2) is styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, dimethylstyrene, α-methylstyrene, p-chlorostyrene, 2,4-dichlorostyrene, and other styrene-derivative monomers, or copolymers, styrene, or at least one of the above styrene derivatives And a binary system with other monomers copolymerizable with these polymers,
Examples thereof include ternary or quaternary or higher copolymers. Further, a mixed composition in which two or more kinds of these polymers are mixed is included.

From the viewpoint of transparency and dispersibility, and in order to suppress the generation of unmelted substances on the sheet as much as possible, it is preferable to use one having the same composition as the styrene resin (a). A styrene homopolymer) is most preferable because it has excellent transparency, is easily available, and is inexpensive. The transparent impact-resistant styrene-based resin (b3) used in the oil-resistant resin layer (B) is not particularly limited as long as it is transparent, but a block copolymer composed of a styrene-based monomer and a conjugated diene monomer is used. Polymers are preferred. As the styrene-based monomer, those having the same composition as the styrene-based resin (b2) are preferable, and styrene is particularly preferable. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3 butadiene, and 1,3-hexadiene, with 1,3-butadiene being preferred. The structure of these block copolymers may be any structure such as AB or ABA. At this time, it is preferable that the portion derived from the conjugated diene monomer is 5 to 40% by weight.
-30% by weight is more preferable. When it is more than 40% by weight, the transparency of the sheet is lowered and the cost is increased, which is not preferable. If the styrene-diene block copolymer is hydrogenated, the transparency of the sheet is lost, which is not preferable.

The mixing ratio of the polyphenylene ether resin (b1), the styrene resin (b2) and the transparent impact resistant styrene resin (b3) forming the oil resistant resin layer (B) of the sheet of the present invention is such that the polyphenylene resin (b3) is mixed. Ether resin (b1) 10 to 40% by weight, styrene resin (b2) 9
0 to 60% by weight, and 3 to 40% by weight of a transparent impact-resistant styrene resin (b3) with respect to 100 parts by weight of these mixed resins.
Parts by weight.

When the polyphenylene ether resin (b1) is less than 10% by weight and the styrene resin (b2) is more than 90% by weight, the styrene resin biaxially stretched laminated sheet obtained has oil resistance and plasticizer resistance. I can't show it to the full. On the other hand, when the polyphenylene ether-based resin is more than 40% by weight and the styrene-based resin (b2) is less than 60% by weight, the transparency of the sheet is lowered and the cost is increased, and the oil resistant resin layer (B) is also used. Since the difference in the melt viscosity between the base material layer (A) and the base material layer (A) becomes large, the sheet formability during coextrusion and the formability during secondary processing become difficult, resulting in poor productivity. More preferably, the proportion of (b1) is 15 to 25% by weight, and that of (b2) is 85 to 75% by weight. These are rationally determined according to the purposes such as oil resistance, plasticizer resistance, and low cost of the product.

Further, a transparent impact resistant styrene resin (b
The mixing ratio of 3) is preferably 5 to 40 parts by weight, and particularly preferably 5 to 20 parts by weight based on 100 parts by weight of the mixed resin of (b1) and (b2). By mixing (b3) within this range, the compatibility between the polyphenylene ether resin (b1) and the styrene resin (b2) can be improved, and as a result, the gelled polyphenylene ether on the surface of the sheet can be improved. It is possible to obtain a sheet having an excellent appearance without the appearance of spots derived from the resin. Further, sufficient folding endurance, which is a requirement of the sheet according to the present invention, can be obtained. Further, by using a transparent impact resistant styrene resin and a polyphenylene ether resin in combination, the oil resistance is further improved.

If the mixing ratio of (b3) is less than 5 parts by weight, the compatibility between the polyphenylene ether resin (b1) and the styrene resin (b2) cannot be improved and sufficient folding endurance cannot be expected. Therefore, when a molded product such as a lid or a container is used, the stress strain applied to the oil resistant resin layer (B) becomes large, and cracks due to insufficient mechanical strength or cracks or whitening due to synthetic edible oils and fats occur. On the other hand, if it is more than 40 parts by weight, the transparency is significantly lowered and the cost is considerably increased.

The mixing method of (b1), (b2) and (b3) is not particularly limited and may be mixing by general melt kneading or mixing by copolymerization. In the case of melt-kneading, the polyphenylene ether resin (b1) and the styrene resin (b2) are melt-kneaded in advance to form pellets, and dry blended with transparent impact-resistant styrene resin (b3) pellets during sheet molding, or A method in which the three members are melt-kneaded and pelletized at the same time is preferable. In the case of copolymerization, the polyphenylene ether resin (b1) is dissolved in an amount of a monomer corresponding to the amount of the styrene resin (b2), polymerized and pelletized, and a transparent impact-resistant styrene resin is used during sheet molding. Dry blend with the resin (b3) pellets, or dissolve the polyphenylene ether resin (b1) and the transparent styrene-butadiene block copolymer in a monomer corresponding to the styrene resin (b2) to co-polymerize the three. A method of pelletizing after polymerization is preferred.

To dissolve the polyphenylene ether resin in the styrene monomer, use an appropriate dissolution tank and use 60 to 1
It is carried out by continuing stirring at a temperature of 00 ° C., preferably 70 to 90 ° C. for 1 to 2 hours. If the melting temperature is lower than 60 ° C, the polyphenylene ether resin will not be sufficiently dissolved to form a slurry, and if it exceeds 100 ° C, the thermal polymerization of styrene will be accelerated.

The type of polymerization may be suspension polymerization, solution polymerization or bulk polymerization. As the radical polymerization initiator, for example, t-butyl peroxide, di-t
-Butyl peroxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, 1,1-
Bis (t-butyl peroxide) cyclohexane, 1,1
Organic peroxides such as -bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propanone
Azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobiscyanovaleric acid, 1-t-butylazo-1-cyanocyclohexane, 1,
Azo compounds such as 1'-azobis-1-carbonitrile may be mentioned. The polymerization initiator can be used in an appropriate amount for polymerizing the styrene-based monomer, but is preferably 0.1 to 10% by weight based on 100 parts by weight of the styrene-based monomer.

The thickness of the oil resistant resin layer (B) is 10 to 100.
It is preferably μm. When the thickness of the oil resistant resin layer (B) is less than 10 μm, even if the proportion of the polyphenylene ether resin (b1) in the oil resistant resin layer (B) is increased, the oil content such as MCT attached to the surface of the molded article is The base material layer (A) also penetrates, and crazes and cracks occur in the molded product. This is especially noticeable if the molded product is damaged. On the other hand, when it exceeds 100 μm, the secondary processability of the sheet is deteriorated and the transparency is poor, so that it becomes unsuitable for use as a food container.

The actual thickness of the oil-resistant resin layer (B) is appropriately selected depending on the application of the container to be molded, the required oil resistance, the plasticizer resistance, and the cost in relation to the layer thickness. For example, when the layer thickness is 200 to 300 μm, the oil resistant resin layer (B) is usually 15 to 90 μm, particularly preferably 20 to 60 μm. The laminated sheet of the present invention is stretched so that the orientation relaxation stress measured according to ASTM D-1504 is 3 to 8 kg / cm ² both in the sheet flow direction and in the direction perpendicular to the sheet, and strength and molding are performed. It has both sex. Orientation relaxation stress is 3kg /
If it is less than cm ² , a molded product having practical strength cannot be obtained, and if it exceeds 8 kg / cm ² , only a molded product having a bad mold can be obtained.

The laminated sheet of the present invention is ASTM D-2 except that the bending angle is changed to 90 ° from side to side.
Folding strength measured in accordance with 176 (average value in vertical and horizontal directions)
However, it is necessary to be 200 times or more. If the folding endurance is less than 200 times, it is not suitable for use as a food container. The laminated sheet of the present invention needs to have an oil resistance of more than 24 hours. Having oil resistance of more than 24 hours means that crazes and cracks do not occur on the sheet surface within 24 hours in the oil resistance evaluation method described below. When the oil resistance is within 24 hours, it is not preferable as a food container which is one of the uses of the sheet of the present invention.

In the laminated sheet of the present invention, the styrene resin (a) used for the base material layer (A) and the styrene resin (b2) constituting the oil resistant resin layer (B) are preferably general purpose polystyrene, The transparency of the laminated sheet measured according to ASTM D-1003 is preferably 70.
% Or more. More preferably, the transparency is 80% or more. If the transparency is less than 70%, the appearance will be poor when used as a food container.

The layer structure of the biaxially stretched styrenic resin laminated sheet of the present invention is not limited as long as the food storage side of the container serves as the oil resistant resin layer (B) when the container is subjected to molding. Considering the balance between the production and the moldability, the two-layer structure and the three-layer structure are particularly preferable. Specifically, a two-layer structure of oil resistant resin layer (B) / base material layer (A) or three layers of oil resistant resin layer (B) / base material layer (A) / oil resistant resin layer (B). The structure is mentioned. By using in this way, the two-layer structure exhibits oil resistance and plasticizer resistance on the inner surface of the container and the flange portion, and the three-layer structure oil resistance on the inner surface of the container and the flange portion. In addition to the plasticizer resistance, it also exhibits good oil resistance and plasticizer resistance at the outer wall and bottom of the container.

If necessary, an adhesive layer, a recovery resin layer at 100% or a free mixing ratio, and an additional layer made of other resin may be added as long as the characteristics of the present invention are not impaired. . The styrene-based resin biaxially stretched laminated sheet of the present invention is prepared by preparing a styrene-based resin (a) for a base material layer (A) and a resin composition (b) for an oil resistant resin layer (B), respectively, It can be easily manufactured according to a more known method for manufacturing a laminated biaxially stretched sheet.

Specifically, (a) using two extruders,
The styrene resin (a) and the resin composition (b) are melt-extruded from each, and the unstretched laminated sheet having the two-layer structure or the three-layer structure is obtained by a multilayer T die having a two-layer or three-layer structure. A method of stretching in a biaxial direction by a known method, (b) using two extruders, melt-extruding the styrene resin (a) and the resin composition (b) from each, and producing two or three single extruders. A layer T die is used to separately obtain one molten sheet for the base material layer (A) and one or two molten sheets for the oil resistant resin layer (B), and while these are still in a molten state. A method in which the unstretched laminated sheet having the two-layer structure or the three-layer structure is pressure-bonded and laminated, and then biaxially stretched by a conventionally known method, (c) a styrene-based resin for the base material layer (A) ( for a biaxially stretched sheet comprising a) and an oil resistant resin layer (B) How prepared separately two biaxially oriented sheets of the biaxially oriented sheet composed of a fat composition (b), it is bonded using an adhesive these biaxially oriented sheet,
And the like.

[0034]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the description of these Examples unless it exceeds the gist. In addition,
In the following description, “part” means weight basis unless otherwise specified. The biaxially stretched sheets obtained in each example and comparative example were evaluated by the following methods. (1) Orientation relaxation stress The orientation relaxation stress of the obtained biaxially stretched sheet is
According to -1504, the sheet was measured in the flow direction and the direction perpendicular thereto. (2) Folding endurance The folding endurance of the obtained biaxially stretched sheet was measured in the sheet flow direction and the direction perpendicular thereto in accordance with ASTM D-2176 except that the folding angle was changed to 90 ° on the left and right. ,
The average was determined. (3) Oil resistance From the obtained biaxially stretched sheet, a lid-shaped molded product (length: 226 m) was subjected to pressure molding (Kansai automatic molding machine PK-450 type).
m, width 147 mm, height 12 mm). At this time, 2
In the case of the seed two-layer sheet, the oil resistant resin layer (B) was placed inside the container. On the other hand, after uniformly applying oil (manufactured by Kao Corporation, brand name Coconade MT, main component: medium-chain fatty acid triglyceride, undiluted solution) to a commercially available rice ball type, and stuffing freshly cooked rice to make a rice ball, A container (length 223 mm,
The width was 144 mm and the depth was 30 mm), and the molding lid was put on and fixed with a rubber band (total weight 360 g). Make a plurality of these and stack them in 3 layers (from the bottom to the 1st, 2nd, 3rd
In the uppermost stage, a dummy whose weight was adjusted was placed, and the dummy was left in a room at 23 ° C., and the molding lids in each stage were checked for the occurrence of crazes or cracks at predetermined intervals. The evaluation criteria are as follows.

XX: Crazes and cracks occurred within 2 hours. X: Crazes and cracks occurred within 6 hours. Δ: Crazes and cracks occurred within 24 hours. O: Crazes and cracks did not occur within 24 hours. , Within 48 hours ⊚: Crazes and cracks did not occur even after 48 hours had passed. (4) Plasticizer resistance A molding lid similar to that used in (3) Evaluation of oil resistance was molded. However, in the case of a two-kind two-layer sheet, the oil resistant resin layer (B) was placed outside the container. Next, (3)
Freshly cooked rice was packed in the same general-purpose polypropylene container used for the evaluation of oil resistance, and a molding lid was put on it (total weight: 360 g). Next, this is applied to a stretch automatic packaging machine (A-12 type manufactured by Fuji Pack System Co., Ltd.), and a commercially available polyvinyl chloride stretch film (Mitsubishi Resin Co., Ltd.)
It was wrapped in plastic wrap (product name: Diamond Wrap).
Make a plurality of these and stack them in 3 layers (1st layer, 2nd layer, 3rd layer from the bottom layer), put a dummy of the weight on the top layer, leave it in a room at 23 ℃ The presence or absence of crazes and cracks was checked for the flanges and corners of the molding lid at each stage every hour. The evaluation criteria are as follows.

×: Crazes and cracks occurred within 6 hours Δ: Crazes and cracks occurred within 24 hours ○: Crazes and cracks occurred within 48 hours ◎: Crazes and cracks did not occur even after 48 hours (5) Transparency The transparency (%) of the obtained biaxially stretched sheet was measured according to ASTM D
It was measured in accordance with -1003 and expressed by the following evaluation criteria.

X: less than 70% Δ: 70% or more, less than 80% o: 80% or more, less than 90% ◎: 90% or more The resins and monomers used are as follows. -Styrene resin (a) (b1): manufactured by Mitsubishi Chemical Corporation,
Product name "Dialex HH-102" (hereinafter GPP
S) ・ Polyphenylene ether resin (b2): Mitsubishi Gas Chemical Co., Inc., trade name "YPX-100L", main component; poly (2,6-dimethyl-1,4-phenylene) ether (hereinafter referred to as PPE) Transparent impact-resistant styrene resin (b3): Asahi Kasei Corporation, trade name "Asaflex 815" (rubber component content about 25%) (hereinafter referred to as SBBC) -Styrene monomer (hereinafter referred to as SM) In the following examples and comparative examples, adjustment / change of the layer constitution ratio of the sheet or adjustment / change of the total thickness of the sheet was performed by controlling the extrusion rate of each extruder and the line speed. Example 1 GPPS as styrene resin (a) for base material layer (A)
It was used. On the other hand, for 20 parts of PPE, GPPS80
Was added and melt-mixed under the condition of 310 ° C. using a co-rotating twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) to pelletize and prepare an intermediate resin composition consisting of two components.
An oil resistant resin layer (B) was obtained by dry blending 5 parts of SBBC pellets with 100 parts of this intermediate resin composition.
It was used as a resin composition (b) for.

Next, two vent type extruders (manufactured by Pla Giken Co., Ltd. and Ikegai Iron Works Co., Ltd.) were used, and a feed block for two kinds of two layers and a coat hanger type T-die (any of them was used. (Plastic Giken Co., Ltd.) is attached, the styrene resin (a) is supplied to one extruder and the resin composition (b) is supplied to the other extruder, and coextruded to a thickness of about 1.
A 4 mm unstretched two-layer sheet was obtained. Subsequently, the unstretched two-layer sheet is stretched in the longitudinal direction by a roll longitudinal stretching machine and then in a tenter transverse stretching machine by about 2.6 times in the longitudinal direction and about 2.5 times in the transverse direction to form a base material layer (A). Has a thickness of 192μ
m, the thickness of the oil resistant resin layer (B) is 18 μm, and the total thickness is 2
A 10 μm biaxially stretched sheet was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 2 70 parts of the same styrene resin (a) as in Example 1 plus 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 1 was used as the base material layer (A), and the oil resistance was increased. The resin composition (b) for the water-soluble resin layer (B) was co-extruded and co-stretched in the same manner as in Example 1 in exactly the same manner as in Example 1, whereby the thickness of the base material layer (A) was 172 μm. A biaxially stretched sheet having an oil-resistant resin layer (B) having a thickness of 40 μm and a total thickness of 212 μm was obtained.

Table 1 shows the evaluation results of the obtained sheet. Example 3 GPPS as styrene resin (a) for base material layer (A)
It was used. On the other hand, GPPS90 for 10 parts of PPE
Was added and melt-mixed under the condition of 310 ° C. using a co-rotating twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) to pelletize and prepare an intermediate resin composition consisting of two components.
A dry blend of 10 parts of SBBC pellets with 100 parts of this intermediate resin composition was used as the resin composition (b) for the oil resistant resin layer (B). After that, by coextruding and costretching in the same manner as in Example 1,
The thickness of the base material layer (A) is 172 μm, and the oil resistant resin layer (B)
To obtain a biaxially stretched sheet having a total thickness of 211 μm.

The evaluation results of the obtained sheet are shown in Table 1. Example 4 70 parts of the same GPPS as in Example 1 plus 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 3 was used as the base material layer (A).
Was used as the resin composition (b) for the oil resistant resin layer (B) obtained by adding 30 parts of SBBC to 100 parts of the same intermediate resin composition as in Example 3, and coextruded in the same manner as in Example 1, By co-stretching, the thickness of the base material layer (A) is 17
A biaxially stretched sheet having a thickness of 1 μm, a thickness of the oil resistant resin layer (B) of 40 μm and a total thickness of 211 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 5 The same resin as in Example 1 was used, except that the feed block was changed from 2-kind 2 layer to 2-kind 3 layer, coextrusion was performed by the same method, and costretching was performed, so that the thickness of the base material layer (A) was 169 μm. ,
A biaxially stretched sheet having a total thickness of 209 μm and a thickness of the oil resistant resin layers (B) on both sides of 20 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 6 A base material layer (A) was obtained by adding 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 5 to 70 parts of GPPS as in Example 1.
The resin composition (b) for the oil resistant resin layer (B) was used in the same manner as in Example 5, and was coextruded and costretched in the same manner as in Example 5 to obtain the base material layer (A). Thickness is 12
0 μm, the thickness of the oil resistant resin layer (B) on both sides is 18 μm
Thus, a biaxially stretched sheet having a total thickness of 156 μm was obtained.

Table 1 shows the evaluation results of the obtained biaxially stretched sheet.
Shown in Example 7 A base material layer (A) was prepared by adding 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 5 to 70 parts of GPPS the same as in Example 1.
Was used as the resin composition (b) for the oil-resistant resin layer (B) in the same manner as in Example 1 except that 20 parts of SBBC was added to 100 parts of the same intermediate resin composition as in Example 1. By extruding and co-stretching, the thickness of the base material layer (A) is 1
70 μm, the thickness of the oil resistant resin layer (B) on both sides is 20 μm
Thus, a biaxially stretched sheet having a total thickness of 210 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 8 70 parts of the same GPPS as in Example 1 plus 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 5 was used as the base material layer (A), and the same intermediate resin as in Example 1 was used. Composition (b ')
By adding 40 parts of SBBC to 100 parts of the resin composition (b) for the oil-resistant resin layer (B), co-extrusion and co-stretching were carried out in the same manner as in Example 5, whereby the base material layer ( The thickness of A) is 176 μm, and the oil resistant resin layers (B) on both sides
To obtain a biaxially stretched sheet having a thickness of 16 μm and a total thickness of 208 μm.

The evaluation results of the obtained sheet are shown in Table 1. Example 9 A base material layer (A) was prepared by adding 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 6 to 70 parts of GPPS the same as in Example 1.
Was used as the resin composition (b) for the oil-resistant resin layer (B) in the same manner as in Example 3 except that 20 parts of SBBC was added to 100 parts of the same intermediate resin composition as in Example 3. By extruding and co-stretching, the thickness of the base material layer (A) is 3
69 μm, the thickness of the oil resistant resin layer (B) on both sides is 39 μm
Thus, a biaxially stretched sheet having a total thickness of 447 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 10 GPPS as styrene resin (a) for base material layer (A)
It was used. GPPS (60 parts) was added to PPE (40 parts by weight), and the mixture was melt-mixed at 320 ° C. using a co-rotating twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) to pelletize an intermediate resin composition consisting of two components. I adjusted it. The same resin as in Example 5, except that the resin composition (b) for the oil resistant resin layer (B) was obtained by adding 10 parts of SBBC to 100 parts of this intermediate resin composition, and coextrusion was carried out by the same method,
By co-stretching, the thickness of the base material layer (A) is 180μ
m, the thickness of the oil resistant resin layers (B) on both sides was 15 μm, and a biaxially stretched sheet having a total thickness of 210 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Example 11 A base layer (A) was obtained by adding 30 parts of the crushed product of the biaxially stretched sheet obtained in Example 6 to 70 parts of GPPS as in Example 1.
The following polymerized product was used as the intermediate resin composition for the oil resistant resin layer (B).

That is, 5.0 kg of PPE and 15.0 kg of SM were placed in a 50 L dissolution layer equipped with an anchor type stirring blade and the temperature was raised to 80 ° C., and stirring was continued for 60 minutes to sufficiently dissolve PPE in SM. Then, 20 kg of hot deionized water, 1.0 kg of sodium dodecylbenzene sulfonate, 450 g of 2% aqueous solution of polyacrylate suspension, sodium sulfate 10
0 g was added and the temperature was raised to 120 ° C. After the temperature reached 120 ° C., 30 g of dicumyl peroxide was added, the temperature was raised to 150 ° C. over 5 hours, and the reaction was completed by keeping it for 1 hour.
After drying the obtained beads, a single screw extruder (Plastic Giken
(Manufactured by Co., Ltd.) was melt-kneaded at 260 ° C. for 1 pass to obtain pellets.

SB was added to 100 parts of this intermediate resin composition.
A dry blend of 5 parts of BC pellets was used as the resin composition (b) for the oil resistant resin layer (B). By coextruding and costretching in the same manner as in Example 5,
A biaxially stretched sheet having a thickness of the base material layer (A) of 175 μm, a thickness of the oil resistant resin layers (B) on both sides of 18 μm and a total thickness of 211 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 1. Comparative Example 1 One vent type extruder (manufactured by Ikegai Tekko Co., Ltd.) was used, and a single layer feed block and a coat hanger type T-die (both manufactured by Pla Giken Co., Ltd.) were attached to the extruder.
GPPS was used as the styrene resin (a). Thereafter, by stretching in the same manner as in Example 1, the total thickness 2
A 10 μm single-layer biaxially stretched sheet was obtained.

The evaluation results of the obtained sheet are shown in Table 2. Comparative Example 2 The same resin as in Example 1 was used, except that the same intermediate resin composition as in Example 3 was used as it was as the resin composition (b) for the oil resistant resin layer (B), and coextrusion and costretching were performed. Due to
The thickness of the base material layer (A) is 192 μm, and the oil resistant resin layer (B)
To obtain a biaxially stretched sheet having a total thickness of 210 μm.

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 3 SBB was added to 100 parts of the same intermediate resin composition as in Example 3.
The same resin as in Example 1 except that 20 parts of C was added to form the resin composition (b) for the oil resistant resin layer (B), coextruded by the same method, and costretched to form a base material layer. (A)
Has a thickness of 205 μm, and the oil-resistant resin layer (B) has a thickness of 5 μm
m, a biaxially oriented sheet having a total thickness of 210 μm was obtained.

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 4 GPPS as the styrene resin (a) for the base material layer (A)
It was used. On the other hand, GPPS50 for PPE50 part
Parts were added and melt-mixed using a co-rotating twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) under the condition of 320 ° C. to prepare an intermediate resin composition consisting of two components by pelletization.
This intermediate resin composition was used as it was as the resin composition (b) for the oil resistant resin layer (B). Thereafter, by coextrusion and costretching in the same manner as in Example 1, the base layer (A) has a thickness of 193 μm, the oil resistant resin layer (B) has a thickness of 16 μm, and the total thickness is 209 μm. Got

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 5 GPPS was used as the resin composition for the base material layer (A). G as the resin composition (b) for the oil resistant resin layer (B)
A dry blend of 20 parts of SBBC pellets with 100 parts of PPS was used. After that, by coextruding and costretching in the same manner as in Example 5, the thickness of the base material layer (A) was 169 μm, and the thickness of the oil resistant resin layers (B) on both sides was 2 μm.
A biaxially stretched sheet having a total thickness of 209 μm and a thickness of 0 μm was obtained.

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 6 Except that the same intermediate resin composition as in Example 1 was used as it is as the resin composition (b) for the oil resistant resin layer (B), the same resin as in Example 5 was coextruded and costretched by the same method. Due to
A biaxially stretched sheet having a thickness of the base material layer (A) of 180 μm, a thickness of the oil resistant resin layers (B) on both sides of 16 μm and a total thickness of 212 μm was obtained.

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 7 A base material layer (A) was prepared by adding 30 parts of the crushed product of the biaxially oriented sheet obtained in Example 5 to 70 parts of the same GPPS as in Example 1.
Was used as the resin composition (b) for the oil-resistant resin layer (B) in the same manner as in Example 5 except that 30 parts of SBBC was added to 100 parts of the same intermediate resin composition as in Example 1. By extruding and co-drawing, the thickness of the base material layer (A) is 2
00 μm, the thickness of the oil resistant resin layer (B) on both sides is 5 μm
Thus, a biaxially stretched sheet having a total thickness of 210 μm was obtained.

The evaluation results of the obtained sheet are shown in Table 2. Comparative Example 8 SBB was added to 100 parts of the same intermediate resin composition as in Example 1.
The same resin as in Example 5, except that 50 parts of C was added to form the resin composition (b) for the oil resistant resin layer (B), was coextruded by the same method, and costretched to form a base material layer ( A) has a thickness of 119 μm, and the oil-resistant resin layers (B) on both sides have a thickness of 1
A biaxially stretched sheet having a total thickness of 155 μm and a thickness of 8 μm was obtained.

Table 2 shows the evaluation results of the obtained sheet. Comparative Example 9 A base material layer (A) was prepared by adding 30 parts of the crushed product of the biaxially stretched sheet obtained in Comparative Example 6 to 70 parts of the same GPPS as in Example 1.
And the same intermediate resin composition as in Example 11 was used as it is, except that the resin composition (b) for the oil-resistant resin layer (B) was used as it was by co-extrusion and co-stretching in the same manner as in Example 5.
A biaxially stretched sheet having a thickness of the base material layer (A) of 171 μm, a thickness of the oil resistant resin layers (B) on both sides of 20 μm and a total thickness of 211 μm was obtained.

Table 2 shows the evaluation results of the obtained sheet.
On the other hand, it is known that even if general-purpose polystyrene is used in place of impact-resistant polystyrene, it can be mixed with polyphenylene ether-based resin at any composition to form a completely compatible system, but in reality, polyphenylene ether-based resin Due to the softening point and low fluidity, it is difficult to completely dissolve it except in special cases. Depending on the kneading and extrusion conditions, "buts" and "burnt poly" derived from unmelted polyphenylene ether-based resin or gelled polyphenylene ether-based resin may be found in the mixed resin composition. These foreign matters, for example, in the case of a colored injection-molded article, will sneak in and become inconspicuous, but in the case of a biaxially stretched sheet for forming a food container, the sheet is easily noticeable because of its transparency, and It must be eliminated as much as possible from the viewpoint of food containers.

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

The styrene resin laminated biaxially stretched sheet of the present invention is a composition of a polyphenylene ether resin, a styrene resin and a transparent impact resistant styrene resin in which an oil resistant resin layer is mixed in a specific mixing ratio. By combining the laminated sheet with specific physical property values, it has excellent oil resistance, plasticizer resistance, folding resistance, transparency, rigidity, and moldability, and the sheet itself can be recycled. It has sufficient strength even in molded products. Therefore, it can be widely used for food packaging sheets that are inexpensive and have excellent properties.
It is especially suitable for packaging foods in which food oil is used.

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Claims (3)

[Claims] 1. A styrene resin laminate comprising a styrene resin (a) as a base layer (A) and an oil resistant resin layer (B) formed on at least one surface of the base layer (A). In the axially stretched sheet, the base material layer (A) has a thickness of 80 to 5
The oil-resistant resin layer (B) is transparent to 100 parts by weight of a resin composition consisting of 10 to 40% by weight of a polyphenylene ether resin (b1) and 90 to 60% by weight of a styrene resin (b2). Impact-resistant styrene resin (b3) is composed of a resin composition in which 5 to 40 parts by weight are blended, the thickness thereof is 10 to 100 μm, and the orientation relaxation stress of the laminated sheet is in the flow direction and the direction perpendicular thereto. Both are biaxially stretched so as to be ³ to 8 kg / cm ² , have a folding strength of 200 times or more, and have an oil resistance of more than 24 hours. Stretched sheet. 2. The styrene resins (a) and (b2) are homopolymers of styrene, and the transparency of the laminated sheet is 70%.
It is above, The styrene resin laminated biaxially stretched sheet of Claim 1 characterized by the above-mentioned. 3. The transparent impact-resistant styrene-based resin (b3) is a block copolymer composed of a styrene-based monomer and a conjugated diene monomer. The styrene-based resin laminated biaxially stretched sheet according to the item.