JP2004075196A - Hermetic container and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold-molding resin sheet with which a cold-molded workpiece with shape retention property to be fixed to a resin container can be obtained, which dispenses with a heater, enables high-speed continuous molding, and in particular enables a highly impact-resistant cold-molded workpiece to be molded. <P>SOLUTION: The cold-molded workpiece made of the resin sheet to be used for manufacturing the cold-molded workpiece to be fixed to a resin molding has shape retention property. The resin sheet contains a polystyrene-based resin and has a base material layer or the base material layer with a functional layer laminated on one or both surfaces thereof. It preferably has, as the functional layer, a sealant layer, an antistatic layer, a printed layer, a barrier layer or the like. Peeling strength between the resin molding and the cold-molded workpiece is preferably 6 to 20 N/15 mm width in a 180° peeling test, and peeling strength between the base material layer and the sealant layer is preferably 3 N/15 mm width or more. <P>COPYRIGHT: (C)2004,JPO

Description

{Circle over (1)} The present invention relates to a sealed container and a method for manufacturing the same, and more particularly, to a sealed container having a shape-retaining lid manufactured using a resin sheet for cold forming and a method for manufacturing the same.

Conventionally, beverage containers, yogurt containers, potion containers, food containers such as cup noodles, and synthetic resin containers for filling disposable medical supplies, etc., have tensile strength, heat resistance, light resistance, moldability, So-called general purpose polystyrene (GPPS) such as styrene homopolymer with excellent surface gloss, or rubber such as SBR and BR mixed with GPPS to improve the brittleness of impact-resistant polystyrene (HIPS) High Impact Polystyrene) is frequently used. As a lid material for bonding and sealing the opening of such a polystyrene resin container, an aluminum laminate having an aluminum foil as a base material and provided on its surface with a sealant layer or the like for adhesion to the container is used. ing. A small piece of aluminum lid material punched out of such an aluminum laminate into a developed form of a lid is formed into a shape with a skirt with an end turned back, and an aluminum lid sealed at the opening of the container is sealed. It is commonly used because it has excellent removability, excellent peel resistance, excellent stability during peeling, and has little adhesion by static electricity when supplied to the opening of a container and has good single-wafer supply properties. In addition, when a skirt formed by bending a peripheral edge portion is provided, the aluminum lid has a property of maintaining a bent and deformed form, that is, a so-called shape retention property. For this reason, when the filled beverage is directly drunk from the container, the state in which the portion in contact with the mouth near the opening of the container is covered with the end of the lid is maintained, and the vicinity of the opening of the container is prevented from being stained. It is preferably used because it is excellent in hygiene and appearance.

However, in recent years, accidents in which foreign substances are mixed in processed food containers have frequently occurred, and safety measures have been an issue. However, in containers using such aluminum lids, metal detectors cannot be used. However, there is a problem in that it is not possible to detect nails, stapler needles, broken pieces of molded product cutting blades, metals such as bolts and nuts, wires, springs and the like which may be mixed. In addition, these containers having an aluminum lid have the disadvantage that the aluminum lid and the container body made of a synthetic resin such as polystyrene must be separately collected, which is inferior in recyclability.

蓋 A lid made entirely of plastic has been proposed as an alternative to such a conventional aluminum lid. For example, a laminated base in which heat-resistant films are laminated on both sides of a base layer of a co-extruded film in which a central layer composed of high-density polyethylene and a polypropylene-based polymer and a coating layer composed of high-density polyethylene on both sides of the central layer. A lid material has been proposed in which a laminated material provided with a sealant layer on the lower surface of a material is punched into a predetermined shape (see Patent Document 1). However, these plastic lids are adhered to the end of the container, and the outer peripheral portion of the adhesive surface is in a flat form extending from the adhesive surface without being folded, so that the beverage filled in the container can be directly discharged from the container. When drinking, it is a hygiene problem. When the container is made of a polystyrene resin such as GPPS or HIPS, the lid and the container body are made of different materials, and the lid and the container need to be separated when discarded.

On the other hand, in a device for filling a liquid such as a beverage into such a container, when a trouble occurs in a line of a molding and filling and sealing process, the container lid is heated when the resin sheet for molding is molded by heating. There is a disadvantage that all the molding resin sheets accumulated in the zone must be discarded, and a means for evacuating the heating device is separately required to avoid such a heated state. Further, when the apparatus is driven, it takes time to raise the temperature to a constant temperature, and loss of the container material sheet and time is inevitable.

In the production of aluminum lids, so-called cold forming is performed in which aluminum foil is sandwiched between male and female molds at room temperature without heating, so-called cold forming, and the formed aluminum lid retains its deformation. However, in the case of plastic lids, when a stress is applied, the shape change of molecules is strongly governed by thermodynamic behavior, so the shape tends to recover by press molding at a temperature lower than the glass transition point. Is strong. For this reason, upon release from the mold immediately after the forming process, elasticity is recovered and the forming accuracy cannot be obtained. Due to the change over time after the forming, the shape of the mold may be reduced by cold forming below the glass transition point. However, a plastic lid having a shape-retaining property in which an end portion is maintained in a state of being bent faithfully has not been obtained. Also, in order to obtain the shape retention of the lid by cold forming, attempts have been made to use a thick sheet or a hard material as the lid material, but a lid having satisfactory shape retention cannot be obtained. In addition, there is an inconvenience that the peeling property of the upper lid is deteriorated.

In addition, a key top plate made of a resin film has been proposed in which a physical plastic deformation process or a physical decompression process applied to a part or all of a base portion is performed by pressing and pressing operations using a sword-shaped jig (see Patent Document 2). There has been proposed a plastically deformed product in which a rubber or resin material preformed by extrusion molding into a sheet shape is subjected to plastic deformation by applying stress while heating (see Patent Document 3), and is formed from a strip-shaped metal plate. An insert forming step, an extrusion forming step of forming a coated strip by co-extrusion and coating rubber or resin with the insert as a core material, and forming a weather strip by plastically deforming the coated strip into a predetermined shape. A method of manufacturing a weather strip having a plastic deformation step and the like has been proposed (see Patent Document 4). However, in the invention described in Patent Document 2, the plastic deformation of the resin film is performed by heating the tip of the jig-shaped jig to a temperature equal to or higher than the glass transition point of the resin film and equal to or lower than the softening point. In the invention described in Patent Document 3, it is necessary to heat a rubber or resin material. In the invention described in Patent Document 4, plastic deformation of a resin whose core is a metal body is described in these publications. The present invention does not relate to a processed product obtained by so-called cold forming only a metal-free resin sheet or a method for producing the same.

On the other hand, in HIPS, the impact resistance increases as the content of the rubber compounded in the polystyrene increases, but the tensile strength, heat resistance, light resistance, moldability, surface glossiness, transparency, etc. decrease. In general, those having a rubber content of 5 to 20% by weight are known. As a method of compounding rubber with polystyrene, a method of dissolving rubber in styrene monomer to polymerize styrene monomer, or a method of mechanically blending rubber and polystyrene, that is, polymers, or mixing both in latex form According to the former method of polymerization, a graft copolymer in which a rubber is provided with a polystyrene side chain is obtained, and the impact resistance is remarkably improved. For example, (a) 5 to 97% by weight of a styrene-based polymer having a syndiotactic structure, (b) 97 to 10% by weight of a rubber-like elastic material containing a styrene component, and a styrene-based polymer 3 having a syndiotactic structure An impact-resistant polystyrene-based resin composition comprising 3 to 95% by weight of a blend of the rubber composition having a styrene component and a polar group of 0 to 10% by weight; An impact-resistant polystyrene-based resin composition has been proposed which has improved properties such as impact resistance and elongation while maintaining properties inherent to polystyrene having a syndiotactic structure, such as heat resistance, chemical resistance, and mechanical strength. (See Patent Document 5).
JP-A-11-10810 JP 2001-76581 A JP 2000-135744 A JP-A-5-237904 JP-A-9-100377

An object of the present invention is to produce a polystyrene-based resin sheet capable of producing a processed product having a shape-retaining property by cold molding, particularly, using a resin sheet for cold molding such as an impact-resistant polystyrene-based resin sheet. It is an object of the present invention to provide a hermetically sealed container provided with a lid and a method for manufacturing the same.

The inventors of the present invention can apply to a conventional filling machine using an aluminum lid material without a lid material heat molding device, that is, as a basic concept of a cold-formed product of a resin sheet, It has shape retention and impact resistance, is excellent in hygiene and appearance, prevents leakage of filling material, enables the use of metal detectors for metal foreign matter inspection, and has the same material as the container Polystyrene resin eliminates the need for separation from polystyrene containers, improves recyclability, excels in peeling properties when opening the lid, and prevents deterioration and deterioration of the filling in the container Started to develop a lid made of steel. When such a resin container is used, not only can the filling machine be prevented from being enlarged, complicated, or slowed down, but also a filling machine that does not include a conventional heat molding device can be used as it is. Therefore, a polystyrene-based resin is selected as the material of the lid as in the case of the polystyrene container, and the material of the resin sheet that can be formed into a lid having excellent shape retention by cold forming, particularly, high impact polystyrene (HIPS) is eagerly studied. Researched, a resin sheet was prepared from a resin composition in which a predetermined impact-resistant polystyrene and a predetermined styrene-butadiene copolymer were mixed at a predetermined ratio, and a lid was prepared from the resin sheet by cold molding. It has been found that the lid has excellent shape retention and can be put to practical use, and the present invention has been completed.

That is, the present invention is a sealed container provided with a resin container and a lid fixed to the resin container, wherein the lid is formed by cold-forming a cold-forming resin sheet, and has shape retention properties. The sealed container according to claim 1, wherein the lid or the lid contains a resin of the same type as the resin molded product as a main component. 3. The resin according to claim 1 or 2, wherein the resin is a polystyrene-based resin, or the resin sheet for cold forming is a substrate on which a substrate layer or a functional layer is laminated. The sealed container (Claim 4) according to any one of claims 1 to 3, wherein the resin sheet for cold forming has a base layer containing a polystyrene resin. The sealed container according to any one of claims 1 to 4 (claim 5), and polystyrene. The sealed container according to claim 5, wherein the resin comprises high-impact polystyrene (HIPS) or a composition comprising high-impact polystyrene and a styrene-butadiene copolymer. Claim 6) Alternatively, impact-resistant polystyrene is obtained by polymerizing a styrene-based monomer in the presence of a rubbery polymer, the weight average molecular weight of the matrix is 150,000 to 300,000, and the styrene content is 82 to The sealed container according to claim 6, wherein the container is made of impact-resistant polystyrene (A) having 94% by weight, a rubber content of 6 to 15% by weight, and a liquid paraffin amount of 0 to 3.0% by weight. 7. The sealed container according to claim 7, wherein the impact-resistant polystyrene (A) has soft component particles having a swelling degree of 30 or less and an average particle diameter in a range of 0.5 to 10 μm. Claim 8) The styrene-butadiene copolymer is a styrene-butadiene copolymer (B) having a styrene content of 30 to 90% by weight and a butadiene content of 10 to 70% by weight. Item 9. The sealed container according to any one of Items 6 to 8 (Claim 9), and a composition comprising 100 to 70% by weight of impact-resistant polystyrene (A) and 0 to 30% by weight of a styrene-butadiene copolymer (B). The sealed container according to any one of claims 6 to 9 (claim 10).

Further, the present invention provides the cold-forming resin sheet, wherein one or two or more functional layers are laminated on both surfaces or one surface of the base material layer. The sealed container (Claim 12) according to any one of claims 4 to 11, wherein the resin sheet for cold forming has a sealant layer as a functional layer. 13. The sealed container according to claim 12, wherein the sealant layer contains a thermoplastic elastomer and / or an ethylene-based copolymer, and the resin sheet for cold molding is charged as a functional layer. The sealed container (Claim 14) according to any one of claims 4 to 13, which has a prevention layer, and the cold-forming resin sheet has a printing layer as a functional layer. Any one of 4 to 14 The sealed container (Claim 15) or the cold sealed resin sheet according to any one of Claims 4 to 15, wherein the resin sheet for cold forming has a barrier layer as a functional layer. The sealing container (Claim 17) according to any one of claims 4 to 16, wherein the molding resin sheet has a strength reinforcing layer as a functional layer, and the strength reinforcing layer is formed of a sealant layer and a base material layer. The sealed container according to claim 17, wherein the strength reinforcing layer contains a polyolefin-based resin (claim 18). (19) The polyolefin-based resin is LLDPE (linear low-density polyethylene), and the sealed container (Claim 20) according to (19) or the resin sheet for cold molding has a function. A wear-resistant layer is displayed as a layer. The sealed container according to any one of claims 1 to 20, wherein the wear-resistant layer is a layer containing a polyolefin resin and / or a nylon resin. The sealed container (Claim 23) according to claim 21, or the polyolefin-based resin is CPP (unstretched polypropylene), wherein the sealed container (Claim 23) according to claim 22 or for cold forming. The sealed container (Claim 24) according to any one of claims 4 to 23, wherein the resin sheet has a functional layer containing a resin of the same type as the base layer, and a resin of the same type as the base layer. 25. The sealed container according to claim 24, wherein the container has a functional layer containing general purpose polystyrene (GPPS) and / or a styrene-butadiene copolymer. The sealed container according to any one of claims 1 to 25, wherein the resin sheet for use has at least one surface having a surface specific resistance value in a range of 10 ⁶ to 10 ¹⁴ Ω, The sealed container according to any one of claims 1 to 26, wherein the cold-forming resin sheet has at least one surface having a surface static friction coefficient in a range of 0.1 to 0.4. ) Or the cold-forming resin sheet is colored white, and the sealed container (Claim 28) according to any one of claims 1 to 27 or the cold-forming resin sheet has a thickness of 50 µm to 1 mm. The peel strength between the sealed container according to any one of claims 1 to 28 and the resin container and the lid is 2 to 30 N / in a 180 ° peel test. The width is 15 mm. 29. The sealed container according to claim 29, wherein the adhesive strength between the base material layer and the sealant layer or the strength reinforcing layer is 3 N / 15 mm width or more. The present invention relates to a sealed container (claim 31).

Further, the present invention, a cold-forming resin sheet, cold-forming at a temperature lower than the glass transition point of the resin constituting the resin sheet to produce a lid having shape retention, the lid and the resin container And the cold forming is performed by pressing a resin sheet for cold forming into a female mold with a male mold and pressing. The method for producing a sealed container according to claim 32, wherein the clearance between the male mold and the female mold is 1.3 to 4.0 with respect to the thickness of the cold-forming resin sheet. 34. The method for producing a sealed container according to claim 32 or claim 33, wherein the resin container is fixed to the lid by an ultrasonic welding method. Item 34. The method for producing a sealed container according to any one of Items 33 to 34 (Claim 35), and a lid. The method for producing a sealed container according to any one of claims 32 to 35, wherein the same kind of resin is contained as a main component, and the same kind of resin is a polystyrene resin. The method for producing a sealed container according to Claim 36 (Claim 37), wherein the resin sheet for cold forming comprises a substrate layer on which a substrate layer or a functional layer is laminated. The method for producing a sealed container according to any one of claims 32 to 37 (claim 38), and the cold-molding resin sheet has a base layer containing a polystyrene resin. 38. The method according to claim 38, wherein the polystyrene-based resin is a high-impact polystyrene (HIPS), or a high-impact polystyrene and a styrene-butadiene copolymer. 40. The method for producing a sealed container according to claim 39, wherein the impact-resistant polystyrene is obtained by polymerizing a styrene-based monomer in the presence of a rubber-like polymer. The obtained matrix has a weight average molecular weight of 150,000 to 300,000, a styrene content of 82 to 94% by weight, a rubber content of 6 to 15% by weight, and a liquid paraffin amount of 0 to 3.0% by weight. 41. The method for producing a sealed container according to claim 40, wherein the polystyrene is a high impact polystyrene (A), and the high impact polystyrene (A) has a swelling degree of 30 or less and 0.5 to 10 μm. 42. The method for producing a sealed container according to claim 41, wherein the styrene-butadiene copolymer has a styrene content of 30 to 90. weight%, 43. The method for producing a sealed container according to claim 40, wherein the styrene-butadiene copolymer (B) has a tadiene content of 10 to 70% by weight. The sealed container according to any one of claims 41 to 43, comprising a composition comprising 100 to 70% by weight of a polystyrene (A) and 0 to 30% by weight of a styrene-butadiene copolymer (B). 44. The method according to claim 38, wherein the resin sheet for cold forming has one or more functional layers laminated on both surfaces or one surface of the base material layer. The sealing method according to any one of claims 38 to 45, wherein the method for producing a sealed container according to any one of Items (44) to (44) and the resin sheet for cold forming has a sealant layer as a functional layer. Container manufacturing method (Claim 46) The method for producing a sealed container according to claim 46, wherein the sealant layer contains a thermoplastic elastomer and / or an ethylene-based copolymer, and cold molding. The method for producing a sealed container according to any one of claims 38 to 47, wherein the resin sheet for use has an antistatic layer as a functional layer (claim 48). The method for producing a sealed container according to any one of claims 38 to 48 (claim 49), wherein the resin sheet for cold molding has a barrier layer as a functional layer. The method for producing a sealed container according to any one of claims 38 to 49 (claim 50), and the cold-molding resin sheet has a strength reinforcing layer as a functional layer. Up to 50 The method for producing a sealed container according to claim 51, wherein the strength reinforcing layer is provided between the sealant layer and the base material layer. (52) The method for producing a sealed container according to (52), wherein the strength reinforcing layer contains a polyolefin resin, or the polyolefin resin is LLDPE (linear low- 54. The method for producing a sealed container according to claim 53, wherein the resin sheet for cold forming has a wear-resistant layer as a functional layer on the surface layer. The method for producing a sealed container according to any one of claims 38 to 54 (claim 55), and the wear-resistant layer is a layer containing a polyolefin resin and / or a nylon resin. Dense The method for producing a cold-formed product according to claim 56, wherein the method for producing a container (claim 56) and the polyolefin resin is CPP (unstretched polypropylene). The method for producing a sealed container according to any one of claims 38 to 57, wherein the resin sheet for interforming has a functional layer containing the same type of resin as the base material layer (claim 58). 59. The method for producing a sealed container according to claim 58, wherein the resin of the same type as the layer has a functional layer containing general purpose polystyrene (GPPS) and / or a styrene-butadiene copolymer. Item 59) or the sealing according to any one of Items 32 to 59, wherein the cold-forming resin sheet has at least one surface having a surface specific resistance of 10 ⁶ to 10 ¹³ Ω. The method for producing a container (Claim 60) and the resin sheet for cold forming has at least one surface having a surface static friction coefficient in a range of 0.1 to 0.4. The method for producing a sealed container according to any one of claims 32 to 61, and the method for producing a sealed container according to any one of claims 32 to 61, wherein the resin sheet for cold forming is colored white. 62) The method for producing a sealed container according to any one of claims 32 to 62, wherein the cold-molding resin sheet has a thickness of 50 µm to 1 mm. The method for producing a sealed container according to any one of claims 32 to 63, wherein the peel strength between the container and the lid is 6 to 20 N / 15 mm width in a 180 ° peel test. , Base layer and sealant layer or strength reinforcing layer 65. The method for producing a sealed container according to claim 64, wherein the adhesive strength between the container and the substrate is 3 N / 15 mm width or more.

According to the sealed container and the method of manufacturing the same of the present invention, a heating device is not required in forming the lid, the size of the device can be reduced, and high-speed continuous molding can be performed. In particular, when manufactured using an impact-resistant polystyrene resin sheet, a cold-formed product having excellent impact resistance and shape retention can be obtained. By using the sealed container of the present invention, inspection using a metal detector can be carried out, so that contamination can be detected beforehand, and the lid and the resin container can be recovered without being separated, and the inside of the resin container can be recovered. Even when a trouble occurs in the filling device of the filling material to be filled in, the softening of the molding resin sheet of the lid supplied to the processing area does not occur, and it is possible to avoid discarding the resin sheet, In addition, the lid can be peeled off from the resin container with a finger, and peeling does not occur even by natural fall.

The sealed container of the present invention is a sealed container provided with a resin container and a lid fixed to the resin container, wherein the lid is formed by cold-forming a cold-forming resin sheet, and has a shape-retaining property. It is not particularly limited as long as it has.

冷 In the present invention, cold molding refers to molding performed in an atmosphere at a temperature lower than the glass transition point (Tg) of the resin. Such cold forming can be performed by using a cold forming machine used for forming aluminum foil or the like, pressing a sheet material into a female mold with a male mold, and pressing at a high speed. According to the interforming, plastic deformation such as molding, bending, shearing, and drawing can be generated without heating.

The above-mentioned plastic deformation refers to a deformation that occurs when the elastic limit is exceeded, and the deformation becomes remarkable when a stress higher than the yield point is applied to the material. For example, in the case of a polystyrene resin, the glass transition point (Tg ), Usually at a temperature of 10 to 60 ° C., preferably at room temperature or at room temperature, when the sheet is whitened, it is necessary to check whether the sheet is plastically deformed. Whether or not whitening has occurred can be visually determined. In addition, the glass transition point (Tg) of each resin is as shown in Table 1.

　本発明の密封容器の蓋は、後述の樹脂容器に固着し、保形性を有するものである。ここで保形性を有するとは、上述のように、折り曲げられて塑性変形された形態を維持する性質を有することをいい、密封容器の蓋が保形性を有するものであれば、その形状・形態は特に制限されない。例えば、ポリスチレン製の樹脂容器の蓋として、ポリスチレン系樹脂シートを用いて冷間成形により作製した蓋の場合、天面Ｔに対して垂直（α＝９０°）に形成されたスカート部分Ｓが、天面Ｔに対してα＝１３０°を保持することができる（図６）場合を好適に例示することができる。

The lid of the sealed container according to the present invention is fixed to a resin container described later, and has a shape-retaining property. Here, having shape retention means, as described above, having the property of maintaining a form that is bent and plastically deformed. If the lid of the sealed container has shape retention, the shape is maintained. -The form is not particularly limited. For example, in the case of a lid made of a polystyrene resin sheet by cold molding as a lid of a polystyrene resin container, a skirt portion S formed perpendicularly to the top surface T (α = 90 °) A case where α = 130 ° can be maintained with respect to the top surface T (FIG. 6) can be preferably exemplified.

The lid of the sealed container of the present invention is not limited at all, such as the material, shape and form, and any material may be used, but one containing the same type of resin as the resin container as a main component, Preferred from the viewpoint of recyclability, for example, PS (polystyrene) resin, AS (styrene-acrylonitrile copolymer) resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, AXS (terpolymer having acrylonitrile and styrene component) ) PS resins such as resins, PET resins such as unsaturated polyester resins and saturated polyester resins, high density polyethylene, low density polyethylene, EVA (ethylene-vinyl acetate copolymer) resin, EVOH (ethylene-vinyl alcohol) Polyethylene resin such as copolymer) resin and polypropylene resin Other polyolefin-based resins, polyacetal-based resins, and those containing a polycarbonate resin and the like can be exemplified, and may also contain one or more of these, among these, Those containing a PS resin, an ABS resin, or a PET resin are preferred. Further, those in which both the lid and the resin container contain a polystyrene-based resin as a main component are preferred because they are excellent in tensile strength, heat resistance, light resistance, moldability, and surface gloss. In addition, additives such as a plasticizer, a stabilizer, a flame retardant, an antioxidant, an ultraviolet absorber, a coloring agent, and an antistatic agent, and auxiliary materials such as a reinforcing agent and a filler are appropriately added to these resins. It may be.

The shape and form of the lid of the sealed container of the present invention are not particularly limited, but a skirt that is fixed to the opening of the resin container and whose peripheral portion is folded to cover the periphery of the opening of the container is formed. The shape is maintained as it is as molded, which is preferable in terms of hygiene and appearance.

樹脂 The resin container of the sealed container of the present invention is not limited at all in terms of material, shape and form. Although any material may be used for the resin container, a resin of the same type as the lid is preferable, and the same resin as the above-mentioned lid can be specifically exemplified. In addition, the additives exemplified as the material of the lid and auxiliary materials may be appropriately added to these resins. The shape and form of the resin container containing such a resin may be any. The molding method is also compression molding, transfer molding, lamination molding, injection molding, extrusion molding, blow molding, calendaring, casting. Any method may be used. Specific examples of such a resin container include a liquid filling container, a beverage filling container, and a food filling container. In particular, beverage filling containers such as lactic acid bacteria beverage containers, and food containers such as dairy products containers eliminate the need for a heating step in a device for filling liquid, reduce the size of the device, even when trouble occurs, This is preferable because it is not necessary to discard the resin sheet of the lid material.

The resin sheet for cold forming used for producing the lid of the sealed container of the present invention is composed of a base material layer (single-layer body) or a base material layer (laminate) in which functional layers are laminated, and the like. Any one of them, a single-layer structure composed of only the base material layer, or a laminated structure in which a functional layer is laminated on both surfaces or one surface of such a base material layer may be used. Good. Examples of the functional layer include a sealant layer having an adhesive function, an antistatic layer having an antistatic function, a barrier layer having a gas permeation blocking function, a printing layer having a display function, a protective layer having a function of protecting the printing layer, and edge cutting. Examples thereof include a strength reinforcing layer having a function of preventing damage and a wear-resistant layer having a function of preventing damage.

The base material layer of such a resin sheet for cold forming is a layer having cold formability that enables to form a secondary processed product having shape retention by plastic deformation due to cold forming of the sheet. The material of the base layer is not particularly limited. For example, PS (polystyrene) resin, AS (styrene-acrylonitrile copolymer) resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, AXS (Terpolymer having acrylonitrile and styrene component) PS resin such as resin, PET resin such as unsaturated polyester resin and saturated polyester resin, high density polyethylene, low density polyethylene, EVA (ethylene-vinyl acetate copolymer) ) Resin, polyethylene resin such as EVOH (ethylene-vinyl alcohol copolymer) resin, Propylene resin, and other polyolefin resins, and polyacetal resin, can be exemplified those containing polycarbonate resin, it may be one containing one or more of these. Among them, those containing a PS-based resin, ABS-based resin, and PET-based resin are preferable, but containing a resin of the same type as the resin container as a main component is particularly preferable because recyclability can be improved. When the resin container mainly contains a polystyrene resin, particularly an impact-resistant polystyrene resin, it is more preferable that the resin container contains a polystyrene resin of the same type as the resin and an impact-resistant polystyrene resin as a main component. In addition, these resins may optionally contain additives such as a plasticizer, a stabilizer, a flame retardant, an antioxidant, an ultraviolet absorber, a coloring agent, an antistatic agent, and auxiliary materials such as a reinforcing agent and a filler. Agent) may be added.

Examples of the polystyrene-based resin contained in the base material layer of the cold-forming resin sheet include a so-called general-purpose polystyrene-based resin, a rubber-modified polystyrene-based resin, and a mixture thereof. Preferably, a rubber-modified polystyrene resin is used, and among rubber-modified polystyrene resins, an impact-resistant polystyrene resin is preferred.In particular, a mixture of the impact-resistant polystyrene resin and a styrene-butadiene copolymer mixed at a predetermined ratio is kneaded. More preferred.

The polystyrene resin for general use is also called GPPS (General Purpose Polystyrene) and is usually a styrene homopolymer, but the resin used for the base layer is not limited to the styrene homopolymer. Examples of the styrene-based monomer of the general-purpose polystyrene-based resin include styrene and styrene having one or more substituents such as an alkyl group and a phenyl group. Specific examples of such a styrene monomer include α-methylstyrene, α-ethylstyrene, α-n-propylstyrene, α-isopropylstyrene, α-n-butylstyrene, α-t-butylstyrene, and o-methylstyrene. , M-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, o-isopropylstyrene, m-isopropylstyrene, p-isopropylstyrene, ot-butylstyrene, m- Examples thereof include alkyl-substituted styrenes such as t-butylstyrene and pt-butylstyrene, and the polystyrene-based resin may be a homopolymer of these monomers or a copolymer of two or more thereof. , As copolymers, random copolymers, alternating copolymers, block copolymers, grafts The polymer or the like may be any one.

As the rubber-modified polystyrene-based resin, any material may be used as long as it is so-called high impact polystyrene (HIPS) in which synthetic rubber is blended with polystyrene. Polystyrene, that is, a method of mechanically blending polymers with each other, or a method of mixing both in a latex state, or a method of dissolving and polymerizing a rubber in a styrene monomer may be used, but the presence of a rubbery polymer may be used. A method of polymerizing a styrene monomer below is preferred. Impact-resistant polystyrene obtained by a method of polymerizing a styrene-based monomer in the presence of such a rubber-like polymer is a graft copolymer in which a polystyrene side chain is attached to rubber, and such impact-resistant polystyrene is a matrix. Having a structure in which soft component particles are dispersed and present in polystyrene to form a soft component particle having a structure in which polystyrene is occluded in a rubbery polymer generally called a salami structure or a single occlusion structure. Are preferred, but not limited to these.

Examples of the styrene-based monomer include the same styrene-based monomers as the above-described GPPS, and examples of the rubbery polymer include polybutadiene, a styrene-butadiene copolymer, and polyisoprene. And a styrene-butadiene copolymer are particularly preferred. Examples of the styrene-butadiene copolymer include SBR-based thermoplastic rubbers, and a styrene-butadiene block copolymer having a structure of SB or SBS, or SEBS obtained by completely or partially hydrogenating them is also used. be able to.

As the rubber-modified polystyrene resin contained in the base material layer, impact-resistant polystyrene alone, or a composition comprising impact-resistant polystyrene and a styrene-butadiene copolymer, among which 100 to 70% by weight of impact-resistant polystyrene And a styrene-butadiene copolymer of 0 to 30% by weight, particularly obtained by polymerizing a styrene-based monomer in the presence of a rubbery polymer, and having a weight average molecular weight of 150,000 to 300,000. In addition, impact-resistant polystyrene having a styrene content of 82 to 94% by weight, a rubber content of 6 to 15% by weight, and a liquid paraffin amount of 0 to 3.0% by weight (hereinafter referred to as "impact-resistant polystyrene (A)") Styrene-butadiene copolymer having a styrene content of 30 to 90% by weight and a butadiene content of 70 to 10% by weight (hereinafter referred to as 100% to 70% by weight). Styrene-butadiene copolymer (B)) containing 0 to 30% by weight of a composition enables plastic deformation by cold forming of a sheet and is obtained by cold forming of a sheet. The lid of the sealed container, which is a secondary molded product, is particularly preferable because it has both excellent impact resistance and shape retention.

When the rubber content of the impact-resistant polystyrene (A) is 6% by weight or more, preferably 9% by weight or more, the sheet does not break during cold forming, and the rubber content is 15% by weight or less. The cold forming is preferable because the sheet is more likely to be plastically deformed, and the lid of the obtained sealed container has sufficient shape retention. The rubber amount of the impact-resistant polystyrene is calculated by a method of calculating from the amount of rubber used at the time of manufacture, or is calibrated by an infrared absorption spectrum (IR) method using an impact-resistant polystyrene containing a known amount of rubber as a standard sample. A line can be created and determined by a method of evaluation.

When the content of the liquid paraffin of the impact-resistant polystyrene (A) is 3.0% by weight or less, preferably 2.0% by weight or less, the sheet is more easily plastically deformed by cold forming, and the sheet is obtained. It is preferable because the lid of the sealed container has a sufficient shape retaining property. Specific examples of such liquid paraffin include cycloparaffins such as cyclopentane, cyclohexane, and cycloheptane, and white mineral oil (a mixture of alkylnaphthene hydrocarbons having an average molecular weight of 300 To about 600 mineral oils).

Among the impact-resistant polystyrenes (A), the weight average molecular weight of the matrix is preferably 150,000 to 300,000, and particularly preferably 200,000 to 250,000. When the lid of the sealed container obtained by the cold forming is a molded product having more appropriate strength, if it is 300,000 or less, the sheet is more easily plastically deformed by cold forming, and the obtained lid has a sufficient shape retention It is preferable because it has properties.

分子 The molecular weight of the impact-resistant polystyrene matrix can be measured by the following method. That is, 1 g of impact-resistant polystyrene is dissolved in 30 ml of a mixed solvent of methyl ethyl ketone / methanol (20/3 volume ratio). Next, the matrix portion and the soft component particles that are insoluble components are separated by centrifugation, the supernatant liquid other than the insoluble components is removed by decantation, and the solution is gradually added to about 500 ml of methanol with stirring to precipitate the polymer portion. . The polymer portion was separated by filtration, methanol was removed by drying, and a solution obtained by dissolving the obtained dried sample in tetrahydrofuran so as to have a concentration of 2 mg / ml was subjected to gel permeation chromatography (GPC). Measure the molecular weight of the matrix. The GPC used is provided with a differential refractometer (RI detector) as a detector, and the molecular weight can be calculated from a calibration curve obtained using commercially available monodisperse polystyrene.

中 で も Also, among the above impact-resistant polystyrenes (A), those having a swelling degree of soft component particles of 30 or less are preferable. When the degree of swelling of the soft component particles is 30 or less, the sheet is more likely to be plastically deformed by cold forming, and the lid of the obtained sealed container has sufficient shape retention.

The degree of swelling can be measured by the following method. That is, 0.4 g of high-impact polystyrene is dissolved in 18 ml of toluene and left for 2 hours or more. The obtained toluene solution is centrifuged (4500 rpm × 2 hours) to separate insoluble components. The supernatant is discarded, the insoluble matter is weighed, and the weight is defined as a. Next, the insoluble matter is dried by a vacuum dryer, and the weight after drying is set to b. The degree of swelling can be determined by a / b.

Further, among the above-mentioned impact-resistant polystyrene (A), those having an average particle size of the soft component particles of 0.5 to 10 μm, particularly 1 to 5 μm are preferable. If it is 0.5 μm or more, preferably 1 μm or more, the sheet will not break during cold forming of the sheet, and if it is 10 μm or less, preferably 5 μm or less, the sheet will be more easily plastically deformed by cold forming. The resulting lid has sufficient shape retention.

平均 The average particle size of the soft component particles can be measured by the following method. That is, high-impact polystyrene is dissolved in methyl ethyl ketone to a concentration of about 1%. This sample solution is irradiated with laser light using a laser diffraction type particle size distribution analyzer (Shimadzu Corporation, SALD1100), and the images of the generated diffracted light and scattered light are detected, and the size of the particles is determined by the pattern and intensity of the image. Calculate weight and quantity. As the average particle diameter, a particle diameter of 50% in the integrated volume distribution can be used.

On the other hand, among the styrene-butadiene copolymers (B), those having a styrene content of 30 to 90% by weight and a butadiene content of 10 to 70% by weight have more excellent lids that are cold-formed from sheets. It is preferable in that it has shape retention and impact resistance.

In the base material layer of such a resin sheet, various additives such as an antioxidant, a plasticizer, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, a release agent, a flame retardant, and a flame retardant may be used, if necessary. Additives such as auxiliaries, pigments, dyes, carbon black, and antistatic agents can be blended, and organic fine particles and inorganic fine particles can be added as long as the performance of the substrate layer is not impaired. Further, the thickness of the base material layer in the resin sheet is not particularly limited, for example, in the case of a polystyrene resin sheet for producing a lid that needs to be peeled between a resin container such as an open container, The range of 50 μm to 1 mm is preferred.

The functional layer laminated on one side or both sides of the base material layer in the resin sheet for cold forming used in the present invention has adhesiveness, antistatic property, abrasion resistance, aesthetics, weather resistance, gas barrier resistance. , Ultrasonic vibration resistance (If there is a fragile part of the molded product (damage to the surface generated during molding) due to vibration and pressure during ultrasonic sealing, the fragile part will be damaged such as perforation and tear) , Resistance to breakage due to this vibration), and resistance to edge breakage (resistance to the fact that the portion that comes into contact with the edge of the seal head is damaged by the vibration and pressure during ultrasonic sealing, making it easier to cut when peeling), etc. It is provided for imparting various functions for improvement, and examples thereof include a sealant layer, an antistatic layer, a printing layer, a barrier layer, a strength reinforcing layer, and a wear-resistant layer. The functional layer may be composed of a multilayer having each function, or may be composed of a single layer having a plurality of functions, as a resin sheet having these functional layers, For example, a sealant layer laminated on both sides or one side of the base material layer, a sealant layer and an antistatic layer respectively laminated on the front and back of the base material layer, a sealant layer on one side of the base material layer Are laminated, a printing layer and an antistatic layer are sequentially provided on the other surface, a sealant layer is laminated on one surface of the base material layer, and a printing layer and a wear-resistant layer are sequentially provided on the other surface. Examples thereof include those in which a barrier layer is laminated between a sealant layer and a base material layer, those in which a strength reinforcing layer is laminated between a sealant layer and a base material layer, and the like. In addition, these functional layers may optionally contain additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a flame retardant, a mineral oil, and an external lubricant. Organic fine particles and inorganic fine particles can be added as long as the performance is not impaired.

As a method for producing a functional layer such as the sealant layer or the antistatic layer, a coating solution containing a component corresponding to each function, for example, an adhesive component or an antistatic agent, is applied to one or both surfaces of the base material layer, and dried. Or a method in which a film in which these components are kneaded with a resin raw material is produced, and this is laminated. As a coating method, a method such as a roll coater, a knife coater, a gravure knife coater, spraying, or the like can be adopted, and the surface of the base material layer may be modified in advance by a corona discharge treatment method, an ozone treatment method, a plasma treatment method, or the like. Good. Further, in the case of a functional film for lamination, from the viewpoint of recyclability, those containing the same type of resin as the substrate layer are preferable. For example, when the substrate layer contains the above-mentioned polystyrene resin, GPPS and / or styrene Those containing a butadiene copolymer are preferred.

シ ー The sealant layer as the functional layer is directly or indirectly laminated on both surfaces or one surface of the base material layer in order to adjust the bonding strength between the lid and the resin container which are cold-formed from the resin sheet. When it is necessary to adjust the fixing strength, such as when it is necessary to peel off the resin container and the lid with a finger, it is preferable to provide a sealant layer, but the resin container and the lid are made of the same resin. When it is not necessary to adjust the fixing strength, for example, in the case of a molded product that is manufactured and has a high fixing strength, it is not necessary to particularly provide the fixing strength. The constituent components of the sealant layer and the thickness thereof are appropriately selected according to the components of the lid and the resin container fixed through the sealant layer and the fixing method (for example, physical heat fusion or chemical adhesion). Can be. Adhesive components in chemical bonding include starch, glue, dextrin, vinyl polymers such as vinyl acetate resin, vinyl chloride resin and acrylic resin, rubbers such as natural rubber, chloroprene rubber and butyl rubber, amino resins, epoxy resins and phenols. Resins, unsaturated polyesters, polyurethanes, polyimides and the like can be mentioned, but rather than the chemical bonding by the sealant layer formed by applying such an adhesive component, the physical properties of the laminating sealant film need not be adjusted for the bonding site. Thermal fusion is preferred. In general, the thickness of the sealant layer is preferably in the range of 10 to 50 μm.

樹脂 In the case of a resin sheet having a sealant layer laminated thereon, the sheets may adhere to each other or may be blocked when stored and transported in a roll shape. In order to prevent this, it is known to laminate an adhesive layer having an adhesive function and a thermoplastic resin layer such as LDPE (low-density polyethylene) which is difficult to adhere by melt co-extrusion (Japanese Patent Application Laid-Open No. Hei 6-1994). No. 31866). The sealant layer in the present invention includes, for convenience, a two-layered structure in which a single-layered adhesive layer having the above-described adhesive function and a thermoplastic resin layer that is difficult to adhere to the adhesive layer are laminated, and the sealant film for lamination is used. As a matter of convenience, a two-layer structure in which an adhesive layer having a single layer and an adhesive layer and another hardly adhered thermoplastic resin layer are laminated is included for convenience. In the present invention, a film in which the adhesive layer and the strength reinforcing layer described below are melt-coextruded and laminated is referred to as a reinforcing sealant film.

Through the laminating sealant film, for example, as a sealant layer in the case of ultrasonically welding a lid and a resin container containing a polystyrene-based resin as a main component, containing a resin of the same type as the base layer as a main component A sealant film can be suitably exemplified, and when another thermoplastic resin is mixed with the same type of polystyrene resin as the resin container or the base material layer, the peel strength can be adjusted by the mixing amount. Further, a sealant film mainly composed of a material having excellent tackiness such as a thermoplastic elastomer or an ethylene copolymer can be preferably exemplified. Examples of the ethylene-based copolymer include an ethylene-vinyl acetate copolymer and an ethylene-unsaturated carboxylic acid ester copolymer. In the sealant layer, if necessary, various additional components such as antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, flame retardants, flame retardant assistants, antistatic agents, pigments, carbon black, Additives such as mineral oil and external lubricant can be blended. Further, organic fine particles and inorganic fine particles can be added as long as the sealing function is not impaired.

The antistatic layer as the above-mentioned functional layer is provided to suppress frictional electrification and enable continuous molding of a lid from a resin sheet. Such an antistatic layer is usually laminated directly or indirectly to the base material layer on the surface opposite to the lamination surface of the sealant layer. When a resin sheet provided with such a functional layer is subjected to continuous cold forming, the sheet and the mold are rubbed in the mold portion and the lid of the molded product is markedly charged. As a result, the obtained lid is formed of metal. The lid from the mold may not be released because it adheres to the mold and overlaps with the next sheet to be supplied, may adhere to the periphery of the mold or the stir part, or the lid may fly in the air immediately after molding. Can be prevented from being transported due to difficulty in taking out and feeding. Such charging of the molded product can be prevented by improving the conductivity of the sheet surface and / or improving the slipperiness of the sheet surface. As an improvement in conductivity, it is preferable that the surface specific resistance value of the resin sheet surface measured in accordance with JIS-K6911 be 10 ⁶ to 10 ¹⁴ Ω. It is preferable that the coefficient of static friction of the resin sheet surface measured according to the above is 0.1 to 0.4.

In order to make the surface specific resistance value of the resin sheet surface 10 ⁶ to 10 ¹⁴ Ω, for example, a surfactant such as an antistatic agent or an antifogging agent, or a conductive substance such as a hydrophilic polymer is used as an antistatic layer. It can be prepared by applying it to the surface of the sheet, or can be prepared as a sheet by kneading an antistatic agent, an antifogging agent, etc. into a resin. For example, in the case of a polystyrene-based resin sheet, when an antistatic layer is formed by applying a conductive substance or the like to the surface of a base material layer of a polystyrene-based resin, the coating amount is preferably in the range of ^{20 to} 500 mg / m ^2. If the surface specific resistance value of the system resin sheet is larger than 10 ¹⁴ Ω, as described above, frictional charging during continuous molding is remarkable, and the molded product may adhere to the mold portion, making it difficult to remove and feed. is there. In order to set the static friction coefficient of the sheet surface to 0.1 to 0.4, for example, as a functional layer, a surface lubricating agent such as a polysiloxane resin is applied to the surface of the sheet, or the functional layer is formed. An agent or the like can be kneaded into a resin to produce a sheet. In preparing the functional layer, the polysiloxane resin can be used in the form of either an oil or an aqueous emulsion. When the polysiloxane resin is applied, the coating amount is preferably in the range of 0.1 to 50 mg / m ² . As described above, an antistatic layer having an antistatic effect having a predetermined surface specific resistance value and a static friction coefficient can be obtained by directly kneading an antistatic agent, a surface lubricating agent, and the like into the raw material resin of the base layer. Can be replaced by

The printing layer as the functional layer is, for example, a product display filled in a sealed container, provided for surface decoration, even if provided on the surface of the base layer, other layers laminated on the base layer. It may be provided between the functional layer, but when having another functional layer on both sides or one side of the base layer, it may be provided between the base layer and the other functional layer It is preferable because the printed surface does not fall off or is damaged by friction between the sheet and the mold during cold forming. As a method of forming the printing layer, a method of forming by printing on the surface of the base material layer, a method of forming by laminating another functional layer on the printing surface applied to the surface of the base material layer, A method in which printing is performed on the back surface of another functional layer produced as a film to also serve as a printing layer, and a method of laminating and forming this printing layer dual-purpose film so that the printing surface is in contact with the base material layer, A method of separately printing a film as a printing layer, laminating the film between a base layer and another functional layer, and the like may be used. Further, the print layer may be one decorated with metallic luster.

The barrier layer as the functional layer imparts weather resistance to light and gas, gas barrier properties, and the like to the resin sheet, and in the case of a lid of a container formed from the resin sheet, prevents deterioration of the filling of the container. It is provided to add a scent function and a function of preventing permeation of water vapor and harmful gas. The barrier layer is usually produced as a gas-impermeable film, and when another functional layer is provided on the surface of the substrate layer or on both surfaces or one surface of the substrate layer, the other functional layer and the substrate It is provided between the layers, for example, between the sealant layer and the base material layer. The gas-impermeable film is preferably a resin film made of a resin containing a resin component constituting the base material layer, and may contain an ultraviolet absorber or the like, if necessary. The thickness of the gas-impermeable film forming such a barrier layer is usually in the range of 10 to 100 μm.

The strength reinforcing layer as the functional layer, for example, when ultrasonically welding a resin molded product such as a container containing a polystyrene resin as a main component and a cold molded product such as a lid, adheres to the resin molded product When the cold-formed product is peeled off with a finger, the corner portion (edge portion) of the top surface of the lid corresponding to the welded portion is damaged, that is, provided to provide resistance to occurrence of edge breakage. By providing a strength reinforcing layer having a function of reinforcing such strength between the base material layer and the sealant layer, the edge cut can be suppressed. The above-mentioned strength reinforcing layer preferably contains a polyolefin-based resin. Examples of the polyolefin-based resin include high-density polyethylene, low-density polyethylene, EVA (ethylene-vinyl acetate copolymer) resin, and EVOH (ethylene-vinyl alcohol). Examples thereof include a polyethylene resin such as a (copolymer) resin and a polypropylene resin, among which low-density polyethylene is preferable, and LLDPE (linear low-density polyethylene) is particularly preferable. In general, the thickness of the strength reinforcing layer is preferably in the range of 10 to 100 μm, particularly preferably in the range of 20 to 45 μm.

The wear-resistant layer as the functional layer is, for example, when the base material layer is mainly composed of a polystyrene-based resin having poor abrasion resistance, the surface is damaged at the time of cold molding, or a resin molded product and a cold-formed product. When ultrasonic welding is performed, it is provided in order to impart resistance to the occurrence of damage such as perforation and tear in the skirt portion of the lid due to the influence of ultrasonic vibration on the damaged portion of the surface, By providing the wear layer on the outermost surface, damage during cold forming or ultrasonic welding can be prevented. The wear-resistant layer is not particularly limited as long as it is a layer containing a wear-resistant resin, and a layer containing a polyolefin-based resin and / or a nylon resin, in particular, a film for lamination can be preferably exemplified. Examples of the polyolefin resin include polyethylene resins such as high-density polyethylene, low-density polyethylene, EVA (ethylene-vinyl acetate copolymer) resin, EVOH (ethylene-vinyl alcohol copolymer) resin, and CPP (unstretched polypropylene). ), OPP (biaxially oriented polypropylene) and other polypropylene-based resins. CPP is particularly preferred because it is excellent in shape retention of the lid by cold molding.

The adhesive strength between the sealant layer as the functional layer and the base material layer, or the adhesive strength between the strength reinforcing layer as the functional layer and the base material layer has a width of 3 N / 15 mm or more, particularly 5 to 8 N / 15 mm. preferable. When the adhesive strength between the sealant layer and the base material layer or between the strength reinforcing layer and the base material layer is 3 N / 15 mm width or more, when the cold-formed product fixed to the resin molded product is peeled off with a finger, the sealant layer is removed. And the occurrence of delamination between the base material layer or the strength reinforcing layer and the base material layer can be suppressed, peeled between the resin molded product and the cold-formed product, and the base material layer and the sealant layer or the strength reinforcing layer Of the sealant layer caused by delamination between the substrate and the base layer can be prevented from adhering and remaining on the resin molded product, and a more remarkable effect can be obtained if the width is 5 to 8 N / 15 mm or more. can get. The adhesive strength can be measured by the following method based on JIS-K6854. That is, using a tensile tester, the non-adhered portion of each of the base material layer and the sealant layer or the strength reinforcing layer and the base material layer is sandwiched by chucks, the opening degree of both layers is set to 180 °, and the tensile speed is 300 mm / min. Pull and measure the load at that time. The adhesive strength can be determined by converting the load into a value of about 15 mm in the adhesive width. Further, when a better releasability between the resin molded product and the cold-formed product is required, in order to obtain comfortable peelability, the flexibility of the functional layer is made larger than that of the base material layer. Preferably, the hardness is smaller than that of the base material layer.

By the way, as described above, the resin sheet for cold forming is usually pressed at room temperature without heating with a male mold against a female mold and pressed at a high speed to form, bend, shear, and draw. Cold forming with plastic deformation such as plastic deformation is performed, but a high-speed impact test at room temperature is considered to be effective as a method for modelly evaluating the plastic deformation of the resin sheet at this time. It is preferable that the cold-forming resin sheet has a specific value in the propagation energy and the maximum load displacement when measured by a falling weight impact test method based on ASTM-D3763.

For example, when the cold-forming sheet contains a polystyrene-based resin, the propagation energy in a 150 μm-thick sheet measured by a falling weight impact test method in accordance with ASTM-D3763 is 0.015 J or more, particularly 0.02 J or more. Is preferred. If the propagation energy is 0.015 J or more, the lid of the cold-formed product that can be sufficiently plastically deformed without breaking the sheet material has a uniform shape and has shape retention, and if it is 0.02 J or more. The effect is more pronounced. Here, the propagation energy of the falling weight impact test refers to the absorbed energy from the displacement at the time of maximum load to the displacement at breaking of the total absorbed energy required for destruction obtained in the falling weight impact test. In addition, the measurement value obtained by the falling weight impact is a value measured at a falling speed of 5.0 M / sec using a weight of φ45 mm for the holder and φ13 mm for the shooting core.

Similarly, when the cold-forming sheet contains a polystyrene-based resin, the maximum load displacement of a 150 μm-thick sheet measured by a falling weight impact test method in accordance with ASTM-D3763 is 10.0 mm or less, particularly 9.5 mm or less. It is preferable that If the maximum load indicating displacement is 10.0 mm or less, the lid that can be sufficiently plastically deformed without breaking the sheet material has a uniform shape and has shape retention, and if the maximum load displacement is 9.5 mm or less, this effect is obtained. Becomes more prominent. Here, the displacement at the maximum load in the falling weight impact test is a displacement amount (a displacement amount between the tip of the falling weight and the surface of the test piece sheet) at the time when the load is maximized. In addition, the measurement value obtained by the falling weight impact is a value measured at a falling speed of 5.0 M / sec using a weight of φ45 mm for the holder and φ13 mm for the shooting core.

The resin sheet for cold forming may be colored, such as white. In particular, when the sheet contains a polystyrene resin, it is preferable that one or both of the base material layer and the functional layer are colored white. When a sheet containing a polystyrene-based resin is formed, the bent portions that have undergone plastic deformation are whitened, so that those layers themselves that are previously colored white can obscure the whitening of the bent portions due to plastic deformation. To color these layers white, a sheet can be prepared by adding a white pigment or dye such as titanium oxide or zinc oxide to the raw resin in an amount of 0.5 to 8% by weight.

The resin sheet for cold forming can be manufactured by a known method using a sheet extruder, a press machine, or the like. For example, a method of simultaneously extruding a base material layer and a functional layer using a sheet extruder, a method of dry laminating a base material layer and a functional layer using a two-component reactive adhesive, A method of laminating a functional layer with a thermal lamination method, a method of extruding and coating a functional layer on a substrate layer, a method of printing on a substrate layer or a functional layer, or these methods Can be produced as a single layer of the base material layer or as a laminate of the base material layer and one or more functional layers.

Although the cold-forming resin sheet has been described in detail above, the thickness of the cold-forming resin sheet varies depending on the type and shape of the lid of the cold-formed product, and is not particularly limited. A sheet having a thickness of 0.2 mm or less recognized as a film and a sheet having a thickness of 1 mm or more recognized as a thin plate are also included in the resin sheet for cold forming used for cold forming. When the cold-molding resin sheet is a sheet containing a polystyrene resin, the thickness is preferably 50 μm to 1 mm, particularly preferably 80 μm to 300 μm. If the thickness of the sheet is 50 μm or more, a strong container lid can be produced from a polystyrene resin sheet, and if the thickness is 80 μm or more, the effect becomes more remarkable, and if it is 1 mm or less, At the time of cold forming, the sheet material is plastically deformed, so that a lid having shape retaining properties can be obtained.

The method for producing the lid of the sealed container of the present invention is a method for cold-forming at a temperature lower than the glass transition point (Tg) of the resin constituting the resin sheet using the cold-forming resin sheet. There is no particular limitation. As described above, the cold forming includes press forming in which a resin sheet is pressed against a mold by air flow such as vacuum forming or compressed air pressure forming, or press forming in which pressing is performed with a roll to form a grain. Etc., but a resin sheet is sandwiched between a pair of male and female molds, the sheet is pushed into the female mold by a male mold, and pressed at a high speed to plastically deform the resin sheet and apply. Molding is preferably performed, and is preferably performed using a cold forming machine used for forming aluminum foil or the like. According to such cold forming, plastic deformation such as molding, bending, shearing, and drawing can be performed on the sheet without heating, and shaping can be performed by shaping. In addition, the plastic deformation is a deformation that occurs when the material exceeds the elastic limit, the deformation becomes remarkable by applying a stress equal to or higher than the yield point to the material, and a molded product having shape retention can be obtained. The molding pressure can be appropriately selected depending on the type of the resin sheet, the shape of the molded product, and the like, and is not particularly limited. As described above, high-speed pressing is usually performed at room temperature or normal temperature without heating, but in some cases, at a temperature substantially lower than the glass transition point (Tg) of the resin sheet under low-temperature heating. You can also.

In particular, when a polystyrene-based resin sheet is cold-formed using an aluminum foil cold-forming machine to produce a lid for a container, the clearance between the male mold and the female mold relative to the thickness of the resin sheet is as follows. It is preferable to use a mold adjusted to 3 to 4.0 times, and it is more preferable to use a mold adjusted to 1.5 to 3.5 times. If the clearance between the male mold and the female mold is 1.3 times or more, the resin sheet will not break during molding, and if the clearance between the male mold and the female mold is 4.0 times or less, the resin The sheet is plastically deformed, and a lid having shape retention can be manufactured. In such an aluminum foil cold forming machine, the forming pressure can be appropriately selected depending on the type of the resin sheet, the shape of the lid, and the like. As described above, high-speed pressing is usually performed at room temperature without heating, but may be performed at a temperature substantially lower than the glass transition point (Tg) of the resin sheet under low-temperature heating in some cases. In the case of a polystyrene-based resin sheet, the temperature is lower than 80 ° C., preferably 10 to 60 ° C., and it is more preferably performed at room temperature or room temperature.

The method of fixing the cold-formed lid to the opening of the resin container may be any method such as adhesion or welding (fusion). The welding methods include hot plate welding, hot air welding, and impulse welding. And an ultrasonic welding method can be exemplified, and among these, the ultrasonic welding method is preferable because the welding can be performed more uniformly and at a high speed. For example, as for the ultrasonic welding of an open resin container and a lid made of a resin sheet having a sealant layer, in addition to a normal ultrasonic welder, an ultrasonic welder of a specific specification for a specific application is performed. It can be performed by applying ultrasonic waves having a frequency of 15 to 50 kHz, preferably 20 to 40 kHz, and an amplitude of 16 to 126 μmpp, preferably 40 to 80 μmpp, to the bonding surface. The conditions of such ultrasonic welding include, for example, when sealing a cold-formed lid at the opening of the polystyrene resin container to form a sealed container, the frequency is 20 to 40 kHz, the output is 50 to 100 w / piece, and the irradiation time is 0.2 to 0.2. One second or the like is preferable, and the lid of a resin container such as a beverage container welded under such conditions can be peeled off with a finger, and the peel strength that the lid does not peel off even if the sealed container is inadvertently dropped is high. can get. In addition, as an adhesion method, various adhesives are applied to a predetermined surface of a lid or a resin container, or a sealant layer containing an adhesive component is provided on a cold-forming resin sheet. A method of adjusting the fixing strength, appropriately applying pressure and welding, or the like can be exemplified by forming a sealant layer having such a fixing strength that it can be peeled off.

As the fixing strength between the resin container and the lid, the peel strength is preferably in a range of 6 to 20 N / 15 mm width in a 180 ° peel test according to JIS-K6854, and more preferably in a range of 8 to 15 N / 15 mm width. Is more preferable. The peel strength was determined by welding a sheet made of a resin raw material having the same composition as the resin molded product and a resin sheet for cold forming by, for example, an ultrasonic welding method, and setting the opening degree of both sheets to 180 ° to obtain a peel strength (180 When the peel strength is 6 N / 15 mm width or more, even if the sealed container is dropped while the contents are filled, the lid peels off from the container and the contents leak. If the peel strength is not more than 20 N / 15 mm width, it is not difficult to peel the lid by hand. It is more preferable that the peel strength is in the range of 8 to 15 N / 15 mm because the above-described effects can be obtained more reliably. Further, when the peel strength between the lid and the open resin container is within the above range, when the lid is pierced with a straw, no peeling occurs between the lid and the resin container, and the resin is filled in the resin container. Drink can be consumed.

As a manufacturing method of the sealed container of the present invention, after forming a lid by cold forming almost simultaneously with punching out a lid material of the expanded form of the lid from the resin sheet, supplying the lid to the opening of the resin container, Specific examples of a method of fixing the cover and the like can be given.

Cold molding of the lid material can be performed using a mold in an atmosphere at a temperature lower than the glass transition point (Tg) of the resin. For example, using a cold forming machine that is widely used for forming aluminum foil etc., sandwich it between a male mold and a female mold, and exceed the elastic limit of the lid material at room temperature without heating, and the yield point of the resin By applying the above-mentioned pressure, plastic deformation such as shearing, bending, drawing and molding is generated in the lid material, and a lid having shape retention can be formed by shaping.

When the lid of the sealed container of the present invention is a polystyrene-based resin, for example, to cold-form using an aluminum foil cold-forming machine, the clearance between the male mold and the female mold is the thickness of the lid material. For example, it is preferable to use a mold adjusted to 1.3 to 4.0 times with respect to 50 μm to 1 mm. Further, it is preferable to use a mold adjusted to 1.5 to 3.5 times. If the clearance between the male mold and the female mold is 1.3 times or more, the lid material will not be broken during molding, and if the clearance between the male mold and the female mold is 4.0 times or less, The lid material is plastically deformed, and a molded product having shape retention can be produced. As the molding conditions at this time, it is preferable to apply pressure at 10 to 60 ° C., particularly at room temperature or normal temperature. After the lid is formed, a lid material is supplied to the opening of the resin container filled with the container, and ultrasonic waves of 20 to 40 kHz are applied on the lid by an ultrasonic welding machine for 0.2 to 1 second so as to have the above-mentioned peel strength. Can be welded and sealed to the resin container.

Hereinafter, embodiments of the sealed container of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments.

[Production of cold forming resin sheet]
The resin was melt-extruded using a 65 mmφT die extruder to produce a 150 μm thick sheet of the following specific examples 1 to 12.
Example 1
Melt extrusion of high impact polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm. As shown in FIG. 1, a sheet of the base material layer 1 was obtained. Then, a sealant layer 2 was produced by laminating a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) on one side by a dry lamination method. The peel strength between the polystyrene resin sheet and the sealant film was 4 N / 15 mm width. On the surface of the base material layer 1 on the side opposite to the surface on which the sealant layer 2 is laminated, an aqueous solution obtained by diluting a surfactant (electro stripper AC, manufactured by Kao Corporation) to a concentration of 30% is applied using a roll coater. An antistatic layer 3 was formed on the sheet surface.

Example 2
Impact-resistant polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm, and styrene A butadiene copolymer (TR2003, manufactured by JSR Corporation; styrene content 40% by weight, butadiene content 60% by weight) was blended at a ratio of 90/10% by weight, and then melt-extruded to obtain a sheet of the base material layer 1. Then, a sealant layer 2 was produced by laminating a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) on one side by a dry lamination method. On the surface of the base material layer 1 on the side opposite to the surface on which the sealant layer 2 is laminated, an aqueous solution obtained by diluting a surfactant (electro stripper AC, manufactured by Kao Corporation) to a concentration of 30% is applied using a roll coater. An antistatic layer 3 was formed on the sheet surface to obtain a resin sheet shown in FIG.

Example 3
Impact-resistant polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm, and styrene A butadiene copolymer (TR2003 manufactured by JSR Corporation) was blended at a ratio of 90/10% by weight, and then melt-extruded to obtain a sheet of the base material layer 1 as shown in FIG. Then, a sealant layer 2 was produced by laminating a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) on one side by a dry lamination method. A printed layer 4 was prepared by laminating a 20 μm back-printed polystyrene resin film on the surface of the base material layer 1 opposite to the surface on which the sealant layer 2 was laminated by dry lamination. An aqueous solution obtained by diluting a surfactant (electrostripper AC, manufactured by Kao Corporation) to a concentration of 30% was applied to the surface of the polystyrene resin film of the printing layer 4 using a gravure coater, and the antistatic layer 3 was applied to the sheet surface. Was prepared.

Example 4
Melt extrusion of high impact polystyrene having a weight average molecular weight of 220,000, a rubber amount of 8% by weight, a liquid paraffin amount of 0.5% by weight, a swelling degree of soft component particles of 11, and an average particle size of soft component particles of 1.0 μm. Thus, a sheet of the base material layer 1 was obtained. Other than that, it carried out similarly to the specific example 1, and obtained the sheet | seat shown in FIG.

Example 5
Impact-resistant polystyrene having a weight average molecular weight of 240,000, a rubber amount of 6.6% by weight, a liquid paraffin amount of 2.5% by weight, a swelling degree of the soft component particles of 12, and an average particle size of the soft component particles of 3.5 μm. The sheet of the base material layer 1 having a thickness of 150 μm was obtained by melt extrusion. Other than that, it carried out similarly to the specific example 1, and obtained the sheet | seat shown in FIG.

Example 6
Melt extrusion of high impact polystyrene having a weight average molecular weight of 250,000, a rubber amount of 9.7% by weight, a liquid paraffin amount of 0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 2.7 μm. Thus, a sheet of the base material layer 1 was obtained. Other than that, it carried out similarly to the specific example 1, and obtained the sheet | seat shown in FIG.

Example 7
Melt extrusion of impact-resistant polystyrene having a weight average molecular weight of 160,000, a rubber amount of 14% by weight, a liquid paraffin amount of 0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.6 μm, A sheet of the material layer 1 was obtained. Other than that, it carried out similarly to the specific example 1, and obtained the sheet | seat shown in FIG.

Example 8
Melt extrusion of high impact polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm. Thus, a sheet of the base material layer 1 was obtained. After that, a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) is laminated on one side to form a sealant layer 2, and then a base opposite to the surface on which the sealant layer 2 is laminated is formed. An aqueous solution obtained by diluting an aqueous emulsion of polydimethylsiloxane (KM787 manufactured by Shin-Etsu Chemical Co., Ltd.) to a concentration of 30% was applied to the surface of the material layer 1 using a gravure coater to form an antistatic layer 3. The sheet shown in No. 1 was obtained.

Example 9
A high impact polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, and a liquid paraffin amount of 1.0% by weight was melt-extruded to obtain a sheet of the base material layer 1. After that, a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) is laminated on one side to form a sealant layer 2, and then a base opposite to the surface on which the sealant layer 2 is laminated is formed. A mixture of a surfactant (electro stripper AC, manufactured by Kao Corporation) and polydimethylsiloxane (KM787, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the material layer 1 to form an antistatic layer 3 as shown in FIG. I got a sheet.

Specific example 10
1 part by weight of a surfactant (Electro Stripper AC manufactured by Kao Corporation) is added to a high-impact polystyrene having a weight-average molecular weight of 230,000, a rubber amount of 12% by weight, and a liquid paraffin amount of 1.0% by weight, followed by melt-extrusion. 1 sheet was obtained. Thereafter, a 30 μm sealant film (LDPE layer 15 μm + adhesive layer 15 μm; ZH-41 manufactured by J-Film Co., Ltd.) was laminated on one side to form a sealant layer 2, and the sheet shown in FIG. 3 was obtained.

Example 11
Impact-resistant polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm, and styrene A butadiene copolymer (TR2003, manufactured by JSR Corporation; styrene content 40% by weight, butadiene content 60% by weight) was blended at a ratio of 90/10% by weight, and then melt-extruded to obtain a sheet of the base material layer 1. Then, a 50 μm reinforcing sealant film (LLDPE layer 35 μm + sealant layer (adhesive layer) 15 μm) is laminated on one side, and a gravure coater is used on the surface of the base material layer 1 opposite to the surface on which the reinforcing sealant film is laminated. Then, an aqueous solution obtained by diluting a surfactant (Electro Stripper AC, manufactured by Kao Corporation) to a concentration of 30% was applied to prepare an antistatic layer 3 to obtain a sheet shown in FIG.

Example 12
Impact-resistant polystyrene having a weight average molecular weight of 230,000, a rubber amount of 12% by weight, a liquid paraffin amount of 1.0% by weight, a swelling degree of soft component particles of 12, and an average particle size of soft component particles of 3.4 μm, and styrene A butadiene copolymer (TR2003, manufactured by JSR Corporation; styrene content 40% by weight, butadiene content 60% by weight) was blended at a ratio of 90/10% by weight, and then melt-extruded to obtain a sheet of the base material layer 1. Thereafter, a 65 μm reinforcing sealant film (LLDPE layer 50 μm + sealant layer (adhesive layer) 15 μm) was laminated on one side, and 30 μm back printing was performed on the surface of the base material layer 1 opposite to the surface on which the reinforcing sealant film was laminated. A CPP (unstretched polypropylene) film 6 was laminated. An aqueous solution obtained by diluting a surfactant (Electro Stripper AC, manufactured by Kao Corporation) to a concentration of 30% was applied to the surface of the CPP film 6 using a gravure coater to prepare an antistatic layer 3, and the sheet shown in FIG. Obtained.

Reference Example An aluminum foil having a thickness of 60 μm was used as a lid sheet.

[Production of lid]
The various sheets of Examples 1 to 10 were pressed with a male mold into a female mold at 23 ° C. under a 23 ° C. atmosphere using a cold forming machine, and the cap shown in FIG. 6 was pressed. A lid 7 having a shape was obtained. The clearance between the male mold and the female mold was 0.3 mm, and continuous molding was performed. The flat part of the lid 7 was φ24.5 mm, and the length of the fold (skirt S) was 5 mm. In the case of the aluminum foil of the reference example having a thickness of 60 μm, the clearance between the male mold and the female mold of the cold forming machine was set to 1.0 mm, and the other conditions were the same as in the specific example.

[Production of sealed container]
The container 8 shown in FIG. 7 was produced by the injection blow molding method. The flange diameter of the container 8 was 24.0 mm, and the capacity was 65 cc. The resin used was impact-resistant polystyrene (H440X manufactured by Nippon Polystyrene Co., Ltd.). The container and the lid were welded by ultrasonic welding under the conditions of a frequency of 20 kHz, an amplitude of 100 μmpp, and 0.5 seconds to obtain a sealed container shown in FIG.

[Characteristic test]
The sheet obtained in Example 1 was subjected to a falling weight impact test by the following method, the surface specific resistance and the coefficient of static friction were measured, and the lid obtained in Example 2 and the sealed container obtained in Example 3 were measured. , Performance, and moldability were evaluated by a four-step evaluation (◎, △, Δ, ×). Table 2 shows the results.
(1) Dropping weight impact test It was based on ASTM D3763. As a measuring instrument, GRAPHIC IMPACT TESTER manufactured by Toyo Seiki Seisaku-sho, Ltd. was used to measure the propagation energy and the displacement at the time of the maximum load. The holder used was a 45 mm diameter φ13 mm spindle, and the falling velocity of the nozzle was 5.0 M / sec. The load cell load was 5000 lb, the load amplifier range was 1 Kunit, the sampling time was 2 μs, and the load input sensitivity was 5 V.
(2) Measurement of surface specific resistance It was based on JIS-K6911. A digital ultra-high resistance / micro ammeter manufactured by Advantest Corporation was used as a measuring instrument.
(3) Measurement of static friction coefficient It was based on JIS-K7125. As a measuring device, a friction measuring device TR manufactured by Toyo Seiki Seisaku-sho, Ltd. was used.
(4) Lid Strength During Molding 13000 shots were molded per hour using a cold molding machine. The molded lid was visually inspected for damage.
(5) Continuous cold formability 13000 shots were formed per hour using a cold forming machine. It was confirmed that the molded lid did not adhere to the mold.
(6) Lid Strength at Ultrasonic Welding The cold-formed lid was welded to a 65 cc container having a flange diameter of 24.0 mm by an ultrasonic welding method. The welded lid of the sealed container was visually inspected for damage (perforation, tear).
(7) Shape Retention An angle α formed between the flat portion and the fold of the molded lid was determined and determined as follows. The judgment was made immediately after molding and after 2 hours. In the table, the bending angle α is shown as ○: 130 ° or less, Δ: more than 130 ° and 150 ° or less, ×: more than 150 °.
(8) Sealability The lid of the hermetically sealed container was lightly tapped with a fingertip to check whether the lid was adhered to the container.
(9) Peelability of sealant layer The lid of the sealed container was peeled off by hand, and it was visually checked whether the sealant layer remained in the container.
(10) Lid Strength at Opening When the lid of the hermetically sealed container was peeled off by hand, it was confirmed whether the lid was torn (cut edge).
(11) Lid Strength at Fall The sealed container was naturally dropped from a height of 100 cm, and it was confirmed whether the lid was torn.
(12) Peelability between lid and container The resin sheet for the lid and the sheet produced using the material for the container were welded by an ultrasonic welding method. The opening strength of both sheets was set to 180 degrees, and the peel strength at 180 degrees was measured and determined. The tester used was Shimadzu Corporation's Autograph AG-500B, and the peeling speed was 300 mm / min. In the table, ：: 6 to 20 N / 15 mm width, Δ: less than 6 N / 15 mm width, and more than 20 N / 15 mm width.
(13) Recyclability It was evaluated whether it was necessary to separate the lid and the container. In the table, ○: separation required, ×: separation required.
(14) Metal detection availability Whether or not inspection was possible using a metal detector was evaluated. In the table, ：: Inspection is possible, ×: Inspection is impossible.

It is a figure which shows one Example of the resin sheet for cold molding used for manufacture of the lid of the sealed container of this invention. It is a figure which shows one Example of the resin sheet for cold molding used for manufacture of the lid of the sealed container of this invention. It is a figure which shows one Example of the resin sheet for cold molding used for manufacture of the lid of the sealed container of this invention. It is a figure which shows one Example of the resin sheet for cold molding used for manufacture of the lid of the sealed container of this invention. It is a figure which shows one Example of the resin sheet for cold molding used for manufacture of the lid of the sealed container of this invention. It is a figure showing a lid of one example of a sealed container of the present invention. It is a figure showing a resin container of one example of a sealed container of the present invention. It is a figure which shows one Example of the sealed container of this invention.

Explanation of reference numerals

1 ... base material layer 2 ... sealant layer (functional layer)
3. Antistatic layer (functional layer)
4 Print layer (functional layer)
5 Strength reinforcement layer (functional layer)
6 Surface layer (functional layer)
7 Lid 8 Container

Claims (65)

A sealed container comprising a resin container and a lid fixed to the resin container, wherein the lid is produced by cold-forming a cold-forming resin sheet, and has a shape-retaining property. container. The sealed container according to claim 1, wherein the lid contains a resin of the same type as the resin molded product as a main component. 3. The sealed container according to claim 1, wherein the same kind of resin is a polystyrene resin. The hermetically sealed container according to any one of claims 1 to 3, wherein the cold-forming resin sheet comprises a base material layer on which a base material layer or a functional layer is laminated. The sealed container according to any one of claims 1 to 4, wherein the cold-forming resin sheet has a base layer containing a polystyrene resin. The sealed container according to claim 5, wherein the polystyrene-based resin contains high-impact polystyrene (HIPS) or a composition comprising high-impact polystyrene and a styrene-butadiene copolymer. Impact-resistant polystyrene is obtained by polymerizing a styrene monomer in the presence of a rubbery polymer, the matrix has a weight average molecular weight of 150,000 to 300,000, a styrene content of 82 to 94% by weight, and a rubber content. The sealed container according to claim 6, characterized in that it is an impact-resistant polystyrene (A) having a content of 6 to 15% by weight and a liquid paraffin content of 0 to 3.0% by weight. The sealed container according to claim 7, wherein the impact-resistant polystyrene (A) has soft component particles having a swelling degree of 30 or less and an average particle diameter in a range of 0.5 to 10 µm. The styrene-butadiene copolymer is a styrene-butadiene copolymer (B) having a styrene content of 30 to 90% by weight and a butadiene content of 10 to 70% by weight. Or a sealed container as described. The composition according to any one of claims 6 to 9, comprising a composition comprising 100 to 70% by weight of impact-resistant polystyrene (A) and 0 to 30% by weight of a styrene-butadiene copolymer (B). Sealed container. The sealed container according to any one of claims 1 to 10, wherein the cold-forming resin sheet has one or two or more functional layers laminated on both surfaces or one surface of the base material layer. The sealed container according to any one of claims 4 to 11, wherein the cold-forming resin sheet has a sealant layer as a functional layer. 13. The sealed container according to claim 12, wherein the sealant layer contains a thermoplastic elastomer and / or an ethylene-based copolymer. The sealed container according to any one of claims 4 to 13, wherein the cold-forming resin sheet has an antistatic layer as a functional layer. The sealed container according to any one of claims 4 to 14, wherein the cold-forming resin sheet has a printed layer as a functional layer. The sealed container according to any one of claims 4 to 15, wherein the resin sheet for cold forming has a barrier layer as a functional layer. The sealed container according to any one of claims 4 to 16, wherein the cold-forming resin sheet has a strength reinforcing layer as a functional layer. The sealed container according to claim 17, wherein the strength reinforcing layer is provided between the sealant layer and the base material layer. 19. The sealed container according to claim 18, wherein the strength reinforcing layer contains a polyolefin-based resin. The sealed container according to claim 19, wherein the polyolefin resin is LLDPE (linear low-density polyethylene). The sealed container according to any one of claims 1 to 20, wherein the resin sheet for cold forming has a wear-resistant layer as a functional layer on a surface layer. The sealed container according to claim 21, wherein the wear-resistant layer is a layer containing a polyolefin-based resin and / or a nylon resin. The sealed container according to claim 22, wherein the polyolefin-based resin is CPP (unstretched polypropylene). The sealed container according to any one of claims 4 to 23, wherein the cold-forming resin sheet has a functional layer containing the same type of resin as the base material layer. 25. The sealed container according to claim 24, wherein the resin of the same kind as the base layer has a functional layer containing general-purpose polystyrene (GPPS) and / or a styrene-butadiene copolymer. The sealed container according to any one of claims 1 to 25, wherein the cold-forming resin sheet has at least one surface having a surface specific resistance in a range of 10 ⁶ to 10 ¹⁴ Ω. The sealed container according to any one of claims 1 to 26, wherein the cold-forming resin sheet has at least one surface having a surface static friction coefficient in a range of 0.1 to 0.4. The sealed container according to any one of claims 1 to 27, wherein the cold-forming resin sheet is colored white. The sealed container according to any one of claims 1 to 28, wherein the cold-forming resin sheet has a thickness of 50 µm to 1 mm. The sealed container according to any one of claims 1 to 29, wherein a peel strength between the resin container and the lid is 2 to 30 N / 15 mm width in a 180 ° peel test. 31. The sealed container according to claim 30, wherein the adhesive strength between the base material layer and the sealant layer or the strength reinforcing layer is 3 N / 15 mm width or more. The resin sheet for cold forming is cold-formed at a temperature lower than the glass transition point of the resin constituting the resin sheet to produce a lid having shape retention, and the lid and the resin container are fixed. Manufacturing method of a sealed container. 33. The method for producing a sealed container according to claim 32, wherein the cold forming is performed by pressing a resin sheet for cold forming into a female mold with a male mold and pressing. 34. The sealed container according to claim 32, wherein the clearance between the male mold and the female mold is adjusted to be 1.3 to 4.0 times the thickness of the cold-forming resin sheet. Production method. The method for producing a sealed container according to any one of claims 33 to 34, wherein the fixing between the resin container and the lid is performed by an ultrasonic welding method. The method for producing a sealed container according to any one of claims 32 to 35, wherein the lid contains a resin of the same type as the resin container as a main component. The method for producing a sealed container according to claim 36, wherein the same kind of resin is a polystyrene resin. The method for producing a sealed container according to any one of claims 32 to 37, wherein the resin sheet for cold forming comprises a substrate layer on which a substrate layer or a functional layer is laminated. The method for producing a sealed container according to any one of claims 32 to 38, wherein the cold-molding resin sheet has a base material layer containing a polystyrene resin. The sealed container according to claim 39, wherein the polystyrene-based resin contains high-impact polystyrene (HIPS) or a composition comprising high-impact polystyrene and a styrene-butadiene copolymer. Production method. Impact-resistant polystyrene is obtained by polymerizing a styrene monomer in the presence of a rubbery polymer, the matrix has a weight average molecular weight of 150,000 to 300,000, a styrene content of 82 to 94% by weight, and a rubber content. 41. The method for producing a sealed container according to claim 40, wherein the high-impact polystyrene (A) is 6 to 15% by weight and the amount of liquid paraffin is 0 to 3.0% by weight. The method for producing a sealed container according to claim 41, wherein the impact-resistant polystyrene (A) has soft component particles having a swelling degree of 30 or less and an average particle diameter in a range of 0.5 to 10 µm. The styrene-butadiene copolymer is a styrene-butadiene copolymer (B) having a styrene content of 30 to 90% by weight and a butadiene content of 10 to 70% by weight. Or the method for producing a sealed container according to the above. The composition according to any one of claims 41 to 43, comprising a composition comprising 100 to 70% by weight of impact-resistant polystyrene (A) and 0 to 30% by weight of a styrene-butadiene copolymer (B). Manufacturing method of sealed container. The sealed container according to any one of claims 38 to 44, wherein the cold-forming resin sheet has one or two or more functional layers laminated on both surfaces or one surface of the base material layer. Production method. The method for producing a sealed container according to any one of claims 38 to 45, wherein the cold-forming resin sheet has a sealant layer as a functional layer. The method for producing a sealed container according to claim 46, wherein the sealant layer contains a thermoplastic elastomer and / or an ethylene-based copolymer. The method for producing a sealed container according to any one of claims 38 to 47, wherein the cold-forming resin sheet has an antistatic layer as a functional layer. The method for producing a sealed container according to any one of claims 38 to 48, wherein the cold-forming resin sheet has a printed layer as a functional layer. The method for producing a sealed container according to any one of claims 38 to 49, wherein the cold-forming resin sheet has a barrier layer as a functional layer. The method for producing a sealed container according to any one of claims 38 to 50, wherein the cold-forming resin sheet has a strength reinforcing layer as a functional layer. The method for producing a sealed container according to claim 51, wherein the strength reinforcing layer is provided between the sealant layer and the base material layer. 53. The method according to claim 52, wherein the strength reinforcing layer contains a polyolefin-based resin. The method for producing a sealed container according to claim 53, wherein the polyolefin resin is LLDPE (linear low-density polyethylene). The method for producing a sealed container according to any one of claims 38 to 54, wherein the cold-molding resin sheet has a wear-resistant layer as a functional layer on a surface layer. The method for producing a sealed container according to claim 55, wherein the wear-resistant layer is a layer containing a polyolefin resin and / or a nylon resin. The method for producing a cold-formed product according to claim 56, wherein the polyolefin-based resin is CPP (unstretched polypropylene). The method for producing a sealed container according to any one of claims 38 to 57, wherein the cold-molding resin sheet has a functional layer containing the same type of resin as the base layer. The method for producing a sealed container according to claim 58, wherein the resin of the same type as the base layer has a functional layer containing general-purpose polystyrene (GPPS) and / or a styrene-butadiene copolymer. . The method for producing a sealed container according to any one of claims 32 to 59, wherein the cold-forming resin sheet has at least one surface having a surface specific resistance in a range of 10 ⁶ to 10 ¹³ Ω. The method according to any one of claims 32 to 60, wherein the cold-forming resin sheet has at least one surface having a surface static friction coefficient in a range of 0.1 to 0.4. The method for producing a sealed container according to any one of claims 32 to 61, wherein the resin sheet for cold forming is colored white. The method for producing a sealed container according to any one of claims 32 to 62, wherein the resin sheet for cold forming has a thickness of 50 µm to 1 mm. The method for producing a sealed container according to any one of claims 32 to 63, wherein the peel strength between the resin container and the lid is 6 to 20 N / 15 mm width in a 180 ° peel test. 65. The method according to claim 64, wherein the adhesive strength between the base material layer and the sealant layer or the strength reinforcing layer is 3 N / 15 mm width or more.

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