JPH09141773A - Polystyrene resin laminated foam sheet and molding, and manufacture of laminated foam sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fitness of printing to a thermoplastic resin film laminated on a foam. SOLUTION: This polystyrene resin laminated foam sheet consists of at least, a thermoplastic resin film, a high-density foam and a low-density foam of polystyrene resin laminated together in that order. The high-density foam has the density of 0.8-0.11g/cm<3> and also the bubble size of O or more and 250μm or less at least, 200μm from a surface with the thermoplastic resin film, and the low-density foam 27 has the density of 0.22-0.04g/cm<3> . Further, the toal thickness of the high-density foam 26 and the low-density foam 27 is 0.7-4.0mm. Besides this foam sheet shows the superior fitness of printing and an outstanding molding characteristic to a deeply drawn shape.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polystyrene-based resin laminated foam sheet and a molded article, and a method for producing a laminated foam sheet. More specifically, the present invention provides a polystyrene-based resin laminated foam sheet having at least two layers of polystyrene-based resin foams having different densities, and further comprising a film laminated on at least the high-density side foam, and a polystyrene-based resin laminated foam sheet obtained from the sheet. And a method for manufacturing a laminated foam sheet. The polystyrene-based resin laminated foam sheet of the present invention is particularly improved in printability, and a deep-drawn molded product can be obtained.

[0002]

2. Description of the Related Art A bowl-shaped food container is formed from a raw material obtained by laminating a film on a polystyrene resin foam (for example, described in Japanese Utility Model Publication No. 62-20269). Food containers are generally printed with various prints,
In order to perform more uniform printing, the polystyrene-based resin laminated foam sheet is subjected to various treatments. For example, a thick film is laminated on a polystyrene resin foam, the bubbles of the polystyrene resin foam are thinned, and the film is laminated. When the polystyrene resin foam is extruded, it is cooled by air etc. Improve the printability of the film by applying a skin layer (generally a bubble diameter of 10 μm or less) (in this case, the bubbles gradually become thinner from the surface layer to about 200 μm, and fine bubbles are generated during film lamination). The polystyrene-based resin laminated foam sheet is provided.

[0003]

However, each of these methods has the following drawbacks. First of all,
It is necessary to make the film as thick as about 200 μm or more, and the container weight becomes heavy. In addition, it is necessary to devise a device to prevent the bubbles in the film from being seen through the film (adding a pigment, printing, etc.), which is costly.

Although the method of (1) can be used for shallow containers,
Formability was poor for deep-drawing containers (container diameter / depth ≤ 2) such as bowl containers. In the method (1), air is applied (generally, the foam is applied from outside and inside of the foam), so that the foam is stretched and the molding is not stable. Further, since the generation of fine bubbles varies, there is a drawback that the whiteness of the appearance changes. Therefore, a method of mixing a white pigment (for example, titanium white) into the film has been adopted, but when the sheet is allowed to flow for a long time, foreign matter adheres to the inside of the mold and it is necessary to frequently clean the mold. Further, there is a drawback that it is costly.

Co-extrusion (coextrusion) for simultaneously extruding a polystyrene resin foam and a film is also known. However, in this case, a method of thinning the cells of the polystyrene resin foam was further required.
Further, the bubbles can be made thinner by lowering the magnification of the foamed body, but if this is done, they are likely to undergo thermal deformation, so they could only be applied to shallow-squeezed containers as food containers to which hot water is poured.

[0006]

In order to solve the above-mentioned problems, the inventors of the present invention can solve the above-mentioned drawbacks by conducting many experiments and researches on polystyrene-based resin laminated foam sheets and their molded products. The present invention has been accomplished by discovering a polystyrene-based resin laminated foam sheet and a molded article, and a method for producing a laminated foam sheet.

Thus, according to the present invention, at least a thermoplastic resin film, a high density foam made of polystyrene resin and a low density foam are laminated in this order,
0.8 to 0.11 g / cm ^{3 when the} high density foam is at least 200 μm from the interface with the thermoplastic resin film.
And a cell size of 5 to 250 μm or less, the low density foam has a density of 0.22 to 0.047 g / cm ³ , and the total thickness of the high density foam and the low density foam is 0. ．
There is provided a polystyrene-based resin laminated foam sheet having a thickness of 7 to 4.0 mm.

Further, according to the present invention, there is provided a molded product obtained from the above-mentioned sheet, which molded product is suitable for a bowl or cup shape. Furthermore, according to the present invention, a thermoplastic resin for forming a thermoplastic resin film and a density of 0.8 to 0.11 g / cm ³ and 5 to 250 μm at least 200 μm from the interface between the thermoplastic resin film and the thermoplastic resin.
Polystyrene resin containing a foaming agent for forming a foam layer having a cell size of 0.22 to 0.047 g / c
Polystyrene resin containing a foaming agent for forming a foam having a density of m ³ is melted by heating with an extruder,
Provided is a method for producing a polystyrene-based resin laminated foam sheet having good printability and formability into a deep-drawing shape, which is characterized by laminating inside or outside a molding die.

Further, according to the present invention, 0.8 to 0.8 at least 200 μm from the interface of the thermoplastic resin film.
Forming a polystyrene-based resin containing a foam density of 0.22~0.047g / cm ³ a foaming agent for forming the foamed layer of the bubble size of the density and 5~250μm of 0.11 g / cm ³ Polystyrene resin containing a foaming agent for heating and melting with an extruder respectively, and laminated inside or outside of a molding die to form a laminated foam sheet, and a thermoplastic resin film is formed into a low density foam of the laminated foam sheet. A method for producing a polystyrene-based resin laminated foam sheet having good printability and formability into a deep-drawing shape, which is characterized by being laminated on the body side.

It is preferable that the thermoplastic resin film be continuously laminated in terms of production efficiency, but it is possible to laminate the thermoplastic resin film after a certain number of days.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a polystyrene resin which is a base resin constituting the high density foam and the low density foam of the present invention, styrene, methylstyrene, ethylstyrene,
Homopolymers of styrene monomers such as isopropylstyrene, dimethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene, or acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, methyl methacrylate, maleic anhydride, butadiene And a copolymer with a vinyl monomer. Specifically, polystyrene resin, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer, high impact polystyrene resin (HIPS), styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene terpolymer Resins having excellent heat resistance and impact resistance such as coalescence are included.

Here, the molded product is prepared by using a microwave oven or the like.
When heating or the like, it is desirable to use a heat resistant resin. For example, when the foam has two layers, it is preferable to use a heat resistant resin for the low density foam inside the molded body. The high density foam on the outer surface may or may not be a heat resistant resin. Furthermore, the above polystyrene-based resin,
For the purpose of modification, a rubber-like substance is added by melting and / or mixing within a range not hindering the object of the present invention within a range of 10 parts by weight or less as a rubber content based on 100 parts by weight of a polystyrene resin. May be. Such rubbery substances include styrene-butadiene block copolymer, styrene-butadiene random copolymer, styrene-isoprene block copolymer, styrene-isoprene random copolymer, low cis polybutadiene, and hydrogenated copolymers thereof. Polymers.

Next, the high-density foam of the present invention has a surface layer having a density of 0.8 to 0.11 g / cm ³ (more preferably 0.35 to 0.12 g / cm ³ ) and a density of 5 to 5. Two
It has a bubble size of 50 μm (more preferably 5 to 170 μm). The cell size D is obtained by cutting the high-density foam into a cross in the flow (MD) direction, the length in the thickness direction being L, and the number of cells between L (excluding fine cells of less than 20 μm). Is represented by N, and is represented by D = N / L, which indicates the average diameter of bubbles existing between L.

When the density is higher than 0.8 g / cm ³ , resin powder is often generated when a container or the like is molded and punched. Moreover, the cut end of the container may be chipped. On the other hand, when the density is less than 0.11 g / cm ³ , the foam is crushed and wrinkles occur in the film when strongly pressed. If the thermoplastic resin film is thin (about 50μ
m or less), the printability becomes poor.

When the bubble size is larger than 250 μm, the thickness of 200 μ, which is often used in deep-drawing containers, is used.
When laminating a thermoplastic resin film having a thickness of m or less, printability is deteriorated. Here, it is difficult to generate a bubble size of less than 10 μm by controlling a nucleating agent or the like, but it is generally known that when the surface of the foam is heated, fine bubbles are generated on the surface ( Japanese Patent Publication No. 5-3820).
Therefore, when the thermoplastic resin film is laminated on the high-density foam, the heat of the film generates fine bubbles having a bubble size of 20 μm or less. In the present invention, the fine bubbles are also included in one of the matters for specifying the high density foam.

The cell size of these high-density foams is generally expanded by heat when molded into a molded article, but even if the volume of the high-density foam after molding is doubled, the volume of the cells is always doubled. Not necessarily. This is because new air bubbles are generated and are different depending on molding conditions (heating temperature, mold temperature, vacuum, mold clearance, press pressure, etc.).

Generally, the foam shape of the foam can be considered by replacing it with a rugby ball shape, a tablet shape, a capsule shape or the like. This bubble is MD x width (TD)
X When considered as thickness (VD), in the case of a polystyrene resin foam sheet formed by normal extrusion (immediately after the die slit or when continuous disturbance from the slit does not forcefully give a disturbance), the dimension in the VD direction Is the smallest. When secondary foaming is performed by heating or the like at the time of molding, it is rare in the normal molding method to increase the dimension in the VD direction by three times or more. Therefore, the correlation with the printability can be seen by measuring the bubble size in the thickness direction.

In the case where a curved surface is printed after molding, a bubble size up to 200 μm (more preferably 500 μm) from the boundary surface between the film and the high density foam on the side where the thermoplastic resin film is laminated. It is preferably 250 μm or less. In addition, fine bubbles (50 μm) that are secondarily generated when heat is applied to the surface of the high-density foam
It is more desirable that the bubbles below) are present. However, regarding the printability of the molded product, although the properties of the thermoplastic resin film are also involved, it is desirable that the thickness of the film is about 120 μm or more even if the above bubble condition is satisfied. In addition, the air bubbles in the printing portion of the molded product satisfy the above conditions, and are 200 μm from the boundary surface between the film of the molded product and the high-density foam.
The density of the polystyrene foam sheet within is about 0.2g
The film thickness may be about 20 μm as long as fine bubbles having a size of / cc or more and about 30 μm are generated.

Next, the low density foam of the present invention is 0.22
~ 0.047 g / cm ³ (more preferably 0.22 to
It has a density of 0.06 g / cm ³ . Here, when the density is higher than 0.22 g / cm ³ , the total density with the high-density foam is higher than 0.2 g / cm ³ , and the economical advantage is reduced. Further, the polystyrene-based resin laminated foam sheet itself becomes thin, resulting in poor heat insulation. On the other hand, when the density is less than 0.047 g / cm ³ , the tendency of bubbles to be communicated becomes strong and the appearance becomes poor. Further, it becomes difficult to form a deep-drawing container such as a bowl.

Further, the total thickness of the high-density foam and the low-density foam is 0.7 to 4.0 mm (more preferably,
1.5-3.0 mm). Here, the thickness is 0.7
If the thickness is smaller than mm, the heat insulating property, strength, etc. of the molded container and the like are deteriorated. For example, when a polystyrene-based resin laminated foam sheet thinner than 0.7 mm is molded, the thickness of the container is often 0.5 mm or less, and when hot water of 95 ° C. or higher is poured, the peak temperature exceeds 75 ° C. Yes, it will be difficult to hold by hand. On the other hand, when the thickness is thicker than 4.0 mm, the molded product is poorly ejected at the time of molding the deep-drawing container. In addition, the thickness of the molded product varies.

Furthermore, the high-density foam and / or the low-density foam contains a filler in an amount of 0.5 to 10 parts by weight (more preferably 0.5 to 7 parts by weight) per 100 parts by weight of the polystyrene resin. Is preferred. By including the filler, it is possible to reduce the remaining of the foaming agent after foaming, and it is possible to suppress secondary foaming during molding. Next, the thermoplastic resin film that can be used in the present invention preferably has a physical property of being stretched by heat molding.

Examples of the resin for the thermoplastic resin film include homopolymers or copolymers of styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, chlorostyrene, bromostyrene, vinyltoluene and vinylxylene. More specifically, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer, impact-resistant polystyrene, styrene-acrylonitrile copolymer, polystyrene resin such as acrylonitrile-butadiene-styrene copolymer. To be

Of the above polystyrene-based resins, polystyrene resins and impact-resistant polystyrene resins are particularly preferable. Further, a mixture of polystyrene resin and high impact polystyrene resin or a high impact polystyrene resin alone, and styrene-
It is more preferable that the butadiene copolymer is dispersed in a salami structure and that the particle diameter of the butadiene copolymer is large in the range of 0.3 μm to 10 μm.

As resins other than polystyrene resins, linear low density polyethylene, high density polyethylene, low density polyethylene, homopolymers such as polypropylene, ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene. -Propylene-butene terpolymer, ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid ester copolymer (for example, ethylene-methyl methacrylate copolymer), ethylene-
Unsaturated carboxylic acid metal salt copolymer (for example, ethylene-
Magnesium acrylate (or zinc) copolymer), propylene-vinyl chloride copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, propylene-olefin copolymer (propylene-ethylene copolymer, Propylene-butene-1 terpolymer), unsaturated carboxylic acids of polyethylene or polypropylene (eg,
Maleic anhydride) modified product, ethylene-propylene rubber,
Atactic polypropylene and the like may be mentioned, and these may be used alone or as a mixture of two or more kinds.

Further, films of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. can also be used. Furthermore, it is also a preferred embodiment to use a film having a gas barrier property. As such a thermoplastic resin film having gas barrier properties, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinylidene chloride, polyamide, polyester, polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, acrylonitrile methyl methacrylate -Butadiene copolymer, nylon, biaxially oriented nylon, biaxially oriented polyethylene terephthalate, biaxially oriented polypropylene, biaxially oriented polystyrene (OP
S), high density polyethylene, ionomer resin (for example, trade name Surlyn), metal vapor deposition film and the like. These may be used alone or may be laminated.

The thickness of the thermoplastic resin film is 20 to 5
The thickness is 00 μm, preferably 35 to 300 μm. Here, for a deep-drawing container, when the thickness is about 20 μm and the thickness is thinner than that, the film thickness of the molded product after molding is about 15 μm and the printability is deteriorated. In addition, when the film is formed into a container, holes are formed in the film. In the current technology, about 5 μm is the limit for stable production. on the other hand,
If the thickness is greater than 500 μm, burn-off will occur on the polystyrene resin sheet during lamination. In addition, since it cannot be produced by coextrusion, it is disadvantageous in terms of manufacturing cost.

When a pigment such as titanium oxide is mixed with a thermoplastic resin film in an amount of 0.3 to 5 parts by weight with respect to 100 parts by weight of the film, it may vary depending on the thickness of the film.
Further, the printability can be improved. Moreover, the thermoplastic resin film, the high-density foam and the low-density foam may be colored in advance with a colorant or the like. Further, printing is usually performed on the surface of the thermoplastic resin film, but it is also possible to perform printing on the thermoplastic resin film in advance and attach them so that the printed surface is on the inner side (side to be laminated). If the printed surface is on the inside, a molded product with a glossy appearance and a clean surface can be obtained.

The polystyrene resin laminated foam sheet of the present invention has a three-layer structure in which at least a low density foam, a high density foam and a thermoplastic resin film are laminated in this order. However, other foams and films may be laminated. For example, combinations of thermoplastic resin film / high density foam / low density foam / thermoplastic resin film, thermoplastic resin film / high density foam / low density foam / high density foam / thermoplastic resin film, etc. Can be mentioned. When a thermoplastic resin film is attached to the low density foam side, the strength of the sheet is improved and a function of suppressing the elongation of the entire skin layer against tensile stress can be imparted. Although printing can be performed, the film preferably has a thickness of 150 μm or more in view of printability.

Next, a method of manufacturing the polystyrene resin laminated foam sheet of the present invention will be described. In the present invention, in order to obtain a foam having a desired density, the types and amounts of the foaming agent and the additives necessary for foaming, and the foaming temperature are appropriately adjusted. First, the high-density foam and the low-density foam can be formed by a known extrusion foaming method. In the extrusion foaming method, a base resin, a foaming agent and additives necessary for foaming are put into an extruder so that a desired density is obtained, and after melting and mixing,
It is done by extrusion from the die. In addition, after the base resin, the foaming agent and the additive are uniformly melted and mixed in advance,
It may be sent to an extruder. Further, the additive may be a so-called masterbatch which is previously added to a resin of the same kind as the base resin at a high concentration.

As the foaming agent which can be used in the present invention, any known foaming agent can be used, and a decomposing type foaming agent, a gas or a volatile foaming agent can be used. As the decomposition type foaming agent, for example,
Inorganic decomposing foaming agents such as ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, calcium azide, sodium azide, sodium borohydride, azodicarbonamide, azobissulfolumamide, azobisisobutyronitrile and diazoamino Azo compounds such as benzene, N, N'-dinitrosopentanemethylenetetramine and N, N'-dimethyl-N, N'-
Examples include nitroso compounds such as dinitrosoterephthalamide, benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide and p, p'-oxybisbenzenesulfonyl semicarbazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, barium azodicarboxylate. . These blowing agents may be used alone or in combination. Further, a known foaming auxiliary agent may be added to adjust the decomposition temperature, the amount of generated gas and the decomposition rate.

As the gas foaming agent, nitrogen, carbon dioxide gas,
Propane, i-propane, n-butane, i-butane, t
tert-butane, methyl ether and the like. Here, the gas means that it is a gas at room temperature.
On the other hand, examples of the volatile foaming agent include ether, petroleum ether, acetone, pentane, isopentane, hexane, isohexane, heptane, isoheptane, benzene and toluene. Water can also be used.

Of the above foaming agents, butane is preferred. When it is desired to reduce the bubble size to about 40 μm or less, it is preferable to use nitrogen or carbon dioxide gas. Also,
Nitrogen and the like have an advantage of being inexpensive because they can be directly separated from air. As an additive necessary for foaming, for example,
Examples thereof include a cell regulator. Specific examples thereof include inorganic powders such as talc and silica, acidic salts such as polyvalent carboxylic acids, and reaction mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate. When the amount of these cell regulators is increased, the cell membrane becomes vulnerable to heat, and the cell membrane may be broken during extrusion lamination, resulting in larger cells. In order to prevent such an increase in bubbles, it is preferable to use nitrogen or carbon dioxide gas as the foaming agent.

Further, if necessary, an ultraviolet absorber, an antioxidant, a coloring agent, a lubricant, a flame retardant, an antistatic agent and the like may be added. The melted and kneaded resin is directly extruded into a sheet shape or a cylindrical shape from a die adjusted to a temperature most suitable for foaming, and then cut into a sheet shape by cutting at an arbitrary line.

Here, in the case of producing a high-density foam, the resin temperature in the extruder is kept at about 85 to 260 ° C., although it depends on the kind of resin used and the like. Also, the base resin 1
It is preferable to add 0.05 to 3.0 parts by weight of the foaming agent and 0.01 to 7.0 parts by weight of the foam control agent to 100 parts by weight. On the other hand, in the case of producing a low-density foam, the resin temperature in the extruder is kept at about 85 to 260 ° C., though it depends on the type of resin used and the like. In addition, the base resin 10
It is preferable to add 1.0 to 7.0 parts by weight of the foaming agent and 0.01 to 5.0 parts by weight of the foam control agent to 0 parts by weight.

Next, the thermoplastic resin film is melted with a film raw material (made of resin, additives, etc.) in a known extrusion method, specifically, an extruder, and a die (T die, coat hanger die, It can be formed by a method of extruding into a film form from a screw die or the like). The high-density foam and the low-density foam may be laminated by a known method such as a coextrusion method, a laminating method using an adhesive, or a fusing method using heat.

The coextrusion method is a method in which the extruded resin is passed through a joining die to be fused and formed into a sheet. When a circular die is used in the co-extrusion method, it is preferable to extrude the high-density foam on the inside (plug side) and the low-density foam on the outside. This is because when the low-density foam is placed inside, bubbles may be crushed by the plug, which makes it difficult to adjust the thickness and density of the foam. Here, in the case of stacking by the co-extrusion method, the density and the cell size at the interface between the high density foam and the low density foam are temporarily increased toward the low density foam. In the present invention, the density and the cell size are limited, but these are matters indicating the state of the surface layer of the high density foam, and the present invention can be applied to the case where the interface is continuous or discontinuous. included.

Further, as the adhesive which can be used in the laminating method using the adhesive, ethylene-vinyl acetate copolymer,
Examples thereof include a methyl methacrylate acrylic polymer elastomer (Toughprene, Tuftec: manufactured by Asahi Kasei Kogyo Co., Ltd.). The adhesive is usually used in a thickness of about 5 μm to 150 μm. The fusion method using heat is, for example, a method in which heat is applied to the high-density foam or the low-density foam with a hot roll and / or hot air, and then the low-density foam or the high-density foam is laminated. It is preferable that the surface of the heat roll is plated with chrome or Teflon to prevent stickiness with the heated foam.

Among the above-mentioned lamination methods, the coextrusion method is preferable in terms of cost and workability. When the bonding method is used, the boundary surface between the high-density foam and the low-density foam is clearly seen, but when coextrusion is used, the boundary surface becomes unclear as described above. The thermoplastic resin film may be coextruded with the above foam, or the film and high density foam may be coextruded, and then the low density foam may be laminated by a bonding method or a fusion method using an adhesive. Good. In addition, when a film is bonded using an adhesive, the thickness of the adhesive is added to the film thickness.

Furthermore, air may be blown onto the surface of the high density foam and / or the low density foam to form a skin on the surface of the foam. In this case, preferably, high density foam side to the 5 ° C. to 45 ° C. only 1 m ² per 0.02m ³ ~0.4m ³ spray of foam air (air ring inlet air temperature), low-density foam side preferred be given 5 ℃ ~45 ℃ 1m ² per 0.01m ³ ~0.3m ³ spray of foam air. Even when the foam is extruded in a single layer and laminated after extrusion, the foam may be blown with air in the same manner on one side and / or both sides of the foam to be laminated. Furthermore, when coextruding the film and foam,
It is preferable to reduce the amount of air on the film surface.

By forming the above-mentioned skin, the appearance is improved and the printability is improved. Further, when the film-printed product is attached to the inside with the foamed product, the appearance becomes glossy. The effect is that the container is finished neatly. Next, FIG. 1 shows an example of a manufacturing apparatus that can be used for manufacturing the polystyrene-based resin laminated foam sheet of the present invention. FIG.
Among them, 1 is a mixing device for mixing a base resin, a foaming agent and an additive, 2 is a hopper for putting the base resin and the additive into a mixer (extruder) 1, and 3 is a foaming device. It is the agent supply port. First, the base resin in the mixer 1 is transferred to the carry-out path 4
It is then conveyed to the extruder 5 and extruded into the merging die 6 under the conditions suitable for foaming to form a high density foam. On the other hand, the low-density foam has a hopper 8 for containing base resin and additives.
And from the extruder 7 provided with the foaming agent supply port 9, it is extruded to the merging die 6 under conditions suitable for foaming.

The foam exiting the confluent die 6 is arbitrarily blown with air by an air ring 10, dimensioned and cooled by a plug 11, and cut into a sheet at an arbitrary position. After that, the foam is wound up by the winding roll 13 via the feed roll 12. The merging die 6 can be configured as shown in FIGS. 2 and 3, for example. First, in FIG. 2, the high-density foam extruded from the extruder 14 is extruded from the extruder 16 via the resin passage 15 and merges with the low-density foam extruded through the resin passage 17. After this, the foam passes through the resin passage 18 and is further formed into an annular shape by the resin passage 19 and is extruded from the extrusion port 20.
The sheet-shaped foam 21 is obtained. Note that FIG. 3 shows a configuration in which the low-density foam is joined at a position after the high-density foam has been formed into an annular shape.

Further, by interposing the thermoplastic resin film laminating device as shown in FIGS. 4 and 5 between the feed roll 12 and the take-up roll 13 of the manufacturing apparatus of FIG. 1, the thermoplastic resin film is continuously laminated. can do. FIG. 4 shows an apparatus for laminating a thermoplastic resin film by extrusion laminating, and 22 represents an extruder equipped with a hopper and a die. On the other hand, FIG. 5 shows an apparatus for laminating a thermoplastic resin film by hot roll lamination, in which 23 is a heat roll and 24 is a hot air applying means which is optionally provided.

In addition, although not shown in the drawing, the thermoplastic resin film, the high density foam and the low density foam can be coextruded at the same time by one merging die. The polystyrene-based resin laminated foam sheet of the present invention can be molded by a known method. The shape of the obtained molded product is not particularly limited, and it can be used for both shallow drawing and deep drawing. However, the laminated foam sheet of the present invention is particularly useful for application to deep-drawing molded products. Here, the deep-drawing molded product refers to a product having a relationship of caliber / depth of the formed product ≦ 2. Further, specific shapes of the deep-drawn molded product include, for example, a bowl shape and a cup shape.

[0044]

The present invention will be described in more detail with reference to the following examples. In the following examples, each data is measured by coloring one of the high density foam and the low density foam. In each example, “part” indicates part by weight. Example 1 100 parts of polystyrene resin HRM-5 (Dencast styrol: Electrochemical Industry KK) was added with a particle size of 5 to 5 as a cell regulator.
Masterbatch mixed with 15 μm talc (talc is kneaded with styrene resin about 20% by weight together with other bubble regulators), and powdered talc and other hydrocerol CF-40S (Dainippon Sumika Kogyo K
K) is appropriately mixed, and N ₂ , CO ₂ and butane (isobutane / normal butane = 7/3) are used as a foaming agent, and the inside and outside of the foam extruded from the die slit of the extruder having a diameter of 90 mm. Air was blown, and a foam sample was made as a prototype.

Approximately 40 μm of H was added to the foam samples.
The IPS film (thermoplastic resin film) was heated and laminated with a heating roll to prepare a laminated sheet of the foam sample and the film. This laminated sheet is a single-shot molding machine (made by Sekisui Plastics)
After the secondary foaming, the thickness is 1.8 to 2.2 times as thick as the original thickness, and then crushed by a press for about 30 to 40%,
A sample for printing confirmation was prototyped.

Next, the pressed sample has a width of 120 mm ×
It is cut to a length of 300 mm and printed with a printing test machine (TOSHIBA MACHINE INDUSTRY KK model GT-13) and printability is very good ◎ (printing quality is good), good ○ (slightly blown out), The results are shown in the following table, which are evaluated as “good” (white spots) and “poor” (white spots and blurring). However, the density, thickness, and bubble size are numerical values of the original fabric.

[0047]

[Table 1]

From Table 1 above, the density is 0.11 to 0.31.
It was found that the printability was improved when the cell size was g / cm ³ and the bubble size was 250 μm (preferably 170 μm) or less.

Example 2 Next, Sample Nos. 3, 4, 7 and 8 were made to have a thickness of about 80 μm.
The HIPS film of m was extrusion laminated, and the printability was confirmed in the same manner as in Example 1. The results are shown in Table 2 below.

[0050]

[Table 2]

From Table 2 above, the foam density was 0.11 g / c.
It was found that when the bubble size was about 240 μm in m ³ , the printability was improved by sticking the film.

Example 3 Next, coextrusion was used to examine the film thickness and printability. First, as the co-extruder, an extruder having a diameter of 90 mm was used for forming a foam, and an extruder having a diameter of 40 mm was used for forming a film. The composition of the raw material of the foam was the same as in Example 1. Further, as the thermoplastic resin film, HIPS with a melt index (hereinafter, MI) 5 was used.

The physical properties and evaluation of the extruded laminated sheet were performed in the same manner as in Example 1. The results are shown in Table 3 below.

[0054]

[Table 3]

From Table 3 above, it was found that good printability was obtained when the thickness of the thermoplastic resin film was 20 μm or more.

Examples 4 to 13 and Comparative Examples 1 to 3 MI 1.0 to 12 (catalog value) polystyrene resin 1
To 00 parts, a masterbatch containing talc having a particle size of 5 to 15 μm (20% by weight of talc by adding other cell regulator and a lubricant), talc powder, and hydrocerol CF-40
S was mixed appropriately, charged into a batch type continuous mixing device on a hopper of an extruder having a diameter of 90 mm, uniformly mixed, and then supplied from the hopper to the extruder. The maximum cylinder temperature of the extruder is 255 ° C., and butane gas (i-butane 70%, n-butane 30%) as a foaming agent is about 1.5 to 8.0% by weight.
In addition, the extrusion rate of about 45 to 80 kg / hour flowed into the joining die. The foam extruded here constitutes a low density foam.

On the other hand, 100 parts of polystyrene resin having MI 2.0 to 20.0 (catalog value) is appropriately mixed with the same masterbatch, talc powder, hydrocerol and the like as described above to prepare a batch on a hopper of a 90 mm extruder. The mixture was charged into a continuous mixing device of a type, uniformly mixed, and supplied from an hopper to an extruder. The maximum cylinder temperature of the extruder was 250 ° C., and the blowing agent was (i-butane 35%, n-butane 6%).
5%) is added to about 0.5 to 4% by weight, and the extrusion rate is about 45 to 75.
It flowed into the merge die at a rate of kg / hour. The foam extruded here constitutes a high density foam.

The resin joined by the joining die has a diameter of 120.
It was poured into a mm mold and extruded into a cylindrical shape from a slit. Immediately after this, air was applied inside and outside the foam to obtain a sheet-shaped foam. The air temperature is 5 ° C to 75 ° C, and the spraying amount is 0.02 to 0.2 m ³ /
m ² and the outer low density side was 0.04 to 0.3 m ³ / m ² .

A thermoplastic resin film was attached to the foam obtained above by a heat roll or extrusion lamination, and a polystyrene resin laminated foam sheet was evaluated. The results are shown in Table 4 below.

[0060]

[Table 4]

From Table 4 above, it was found that the printability was improved when the thickness, cell size and density of the high density foam were within the range of the present invention. Further, a cross-sectional photograph of the polystyrene-based resin laminated foam sheet of Example 5 is shown in FIG. 6 (however, before laminating the thermoplastic resin film). As is clear from this figure, in the laminated foam sheet of Example 5, the boundary between the high-density foam and the low-density foam forming the same is not clear. On the other hand, cross-sectional photographs of the polystyrene resin laminated foam sheet of Example 13 are shown in FIG. 7 (however, before laminating the thermoplastic resin film) and FIG. 8 (however after laminating the thermoplastic resin film).
It was shown to. As is clear from this figure, the laminated foam sheet of Example 13 was composed of the thermoplastic resin film 25, the high density foam 26 and the low density foam 27. Also,
At the interface between the high-density foam 26 and the low-density foam 27, a transition layer in which the density and the cell size change stepwise was formed.

Example 14 A HIPS film was laminated on the original fabric of Example 5, pressed after secondary foaming, and the printability was evaluated by the same method as in Example 1. Table 5 shows the results.

[0063]

[Table 5]

From the above Table 5, it was found that the thicker the thermoplastic resin film, the better the printability.

Example 15 The polystyrene resin laminated foam sheets of Examples 4, 8, 9 and 10 and Comparative Examples 1, 2 and 3 were molded into a bowl-shaped container using a single-shot molding machine (manufactured by Sekisui Plastics). Then, print with a curved surface printing machine (KK5 / 5-861 / DIR.R type manufactured by Hubei Seiko), UV ink flash dry C manufactured by Toyo Ink Mfg. Co., Ltd.
Performed using URE. The printability of the obtained molded product was evaluated in the same manner as in Example 1. The results are shown in Table 6 below. The number of evaluation samples was 50 for each.

[0066]

[Table 6]

From Table 6 above, the laminated foam sheet of the present invention is
It was found that it has good printability even after molding. From the above Examples 1 to 15 and Comparative Examples 1 to 3, the following was found. (1) It is preferable that the film on the printed surface of the laminated foam sheet is thick and the bubbles of the foam below the film are thin. However, air bubbles may be restricted by the molded product in relation to moldability, and it is necessary to take measures as necessary. However, the density of the high density foam at the bottom of the thermoplastic resin film is a ^{0.8g / cm 3 ~0.11g / cm 3} , printability if present more than about 200μm from the film surface be significantly improved I understood. (2) Coextrusion is the most economical method for producing a laminated foam sheet in the present invention. However, when co-extruding a high-density foam and a low-density foam, there is no significant difference in cell size,
It was difficult to divide them because the boundary surface was unclear. (3) The finer the bubbles of the foam to be bonded with the film, the better as long as the moldability is maintained. However, even if it is made thin, the printability will not be improved if the bubbles grow large by heating during molding. Therefore, the bubble must be sized after allowing for growth. For that purpose, it is necessary to make the bubbles thin or reduce the amount of the foaming agent to suppress the secondary foaming. For this purpose, the density of the foam is restricted and the residual gas in the foam is reduced. Communicate bubbles, or N
₂ , using a foaming agent that does not have a secondary foaming property such as CO ₂ ,
It turns out that it can be adjusted. (4) In order to reduce the residual gas in the foam, a large amount of filler (usually 1 to 15% by weight) can be used, or a hot roll or hot air treatment can be performed before laminating the films. (5) When the cells are thin, the adhesion becomes weak when laminating the film on the high-density foam, which causes a problem. In this case, it can be improved by mixing the same material as that of the film with the foam (for example, when the HIPS film is stuck, the HIPS film can be mixed with the foam.
Etc.).

Examples 16 to 22 Talc was mixed in a high-density foam, coextruded with a low-density foam, and a film was stuck to evaluate the printing.

Talc was prepared by kneading in HIPS beforehand to prepare a masterbatch (the particle size of talc is 5 to 2).
5 μm or so was used). The thermoplastic resin film was laminated by extrusion lamination. The results are shown in Table 7 below.

[0070]

[Table 7]

In Example 16, the cell size of the high-density foam of the molded product was about 1.5 times larger than that of the original fabric, but the printability was good. In Example 17, the bubble size was as large as in Example 16, but the bubble size of the raw fabric was small, so the bubble size of the obtained molded product was also relatively small, and the printability was very good.

In Examples 18 and 19, the bubble sizes were about 1.4 times and 1.2 times, respectively. In Examples 20 and 21, the formation of bubbles was poor, and molded products having good and slightly good printability were obtained. In Example 22, no bubbles were formed, the surface of the foam sheet was rough, and the printability was poor.

Therefore, the more preferable addition amount of the filler from Table 7 is 0.6 to 100 parts by weight of the base resin.
It was found to be in the range of 7 parts by weight.

[0074]

The polystyrene-based resin laminated foam sheet of the present invention comprises at least a thermoplastic resin film, a high-density foam made of polystyrene-based resin, and a low-density foam laminated in this order. 0.8 at least 200 μm from the interface with the thermoplastic resin film
The low density foam has a density of 0.11 g / cm ³ and a cell size of 5 to 250 μm or less, and is 0.22 to 0.04.
It has a density of 7 g / cm ³ , and is characterized in that the total thickness of the high-density foam and the low-density foam is 0.7 to 4.0 mm. Therefore, it has good printability and moldability into a deep-drawn shape.

At least one of the high-density foam and the low-density foam uses the polystyrene resin 100 as a filler.
By including 0.5 to 10 parts by weight with respect to parts by weight, the remaining foaming agent can be reduced and secondary foaming at the time of molding can be suppressed. Furthermore, since at least one of the high-density foam and the low-density foam is made of a heat-resistant polystyrene-based resin, it can be suitably used for a molded product containing a hot liquid or the like.

Further, since at least one of the high-density foam and the low-density foam contains a rubber component, the polystyrene resin can be modified to have desired properties.
Further, since the thermoplastic resin film has a gas barrier property, it can be used, for example, for producing a molded product having good storage stability such as food. Further, the high-density foam, the low-density foam and the thermoplastic resin film can be colored in a desired color.

Furthermore, according to the above sheet, it is possible to obtain a bowl-shaped or cup-shaped molded article having good printability. Further, the polystyrene-based resin laminated foam sheet of the present invention has a density of 0.8 to 0.11 g / cm ³ and a thermoplastic resin for forming a thermoplastic resin film and at least 200 μm from the interface between the thermoplastic resin film and the thermoplastic resin. A polystyrene-based resin containing a foaming agent for forming a foam layer having a cell size of 5 to 250 μm;
By heat-melting each of the polystyrene-based resins containing a foaming agent for forming a foam having a density of 0.047 g / cm ³ with an extruder and stacking them inside or outside a molding die, it is easy. Therefore, it is possible to reduce the manufacturing costs such as aging and storage.

Also, 0.8 to 0.11 g / cm at least 200 μm from the interface of the thermoplastic resin film.
A polystyrene-based resin containing a foaming agent for forming a foam layer having a density of ³ and a cell size of 5-250 μm;
Polystyrene resin containing a foaming agent for forming a foam having a density of 0.22 to 0.047 g / cm ³ is melted by heating with an extruder, and laminated inside or outside a molding die. By forming a foamed sheet and laminating a thermoplastic resin film on the low-density foamed body side of the laminated foamed sheet, it can be easily manufactured, and manufacturing costs such as aging and storage can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of an apparatus for producing a polystyrene-based resin laminated foam sheet of the present invention.

FIG. 2 is a schematic enlarged cross-sectional view of the merge die of FIG.

FIG. 3 is a schematic enlarged cross-sectional view of the merge die of FIG.

FIG. 4 is a schematic view of a means for laminating a thermoplastic resin film of the present invention.

FIG. 5 is a schematic view of a means for laminating a thermoplastic resin film of the present invention.

FIG. 6 is a cross-sectional photograph of a polystyrene-based resin laminated foam sheet of Example 5 (before laminating a thermoplastic resin film).

FIG. 7 is a cross-sectional photograph of a polystyrene-based resin laminated foam sheet of Example 13 (before laminating a thermoplastic resin film).

FIG. 8 is a cross-sectional photograph of a polystyrene-based resin laminated foam sheet of Example 13 (after laminating a thermoplastic resin film).

[Explanation of symbols]

 1 Mixing Device (Extruder) 2, 8 Hopper 3, 9 Foaming Agent Supply Port 4 Carrying Out Path 5, 7, 14, 16, 22 Extruder 6 Confluence Die 10 Air Ring 11 Plug 12 Feed Roll 13 Winding Roll 10 15, 17, 18, 19 Resin Passage 20 Extrusion Port 21 Foam 23 Heat Roll 24 Hot Air Supply Means 25 Thermoplastic Resin Film 26 High Density Foam 27 Low Density Foam

[Procedure amendment]

[Submission date] February 19, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

Next, the high-density foam of the present invention has a surface layer having a density of 0.8 to 0.11 g / cm ³ (more preferably 0.35 to 0.12 g / cm ³ ) and a density of 5 to 5. Two
It has a bubble size of 50 μm (more preferably 5 to 170 μm). The cell size D is obtained by cutting the high-density foam into a cross in the flow (MD) direction, the length in the thickness direction being L, and the number of cells between L (excluding fine cells of less than 20 μm). Is expressed as N , and D = L / N , which indicates the average diameter of bubbles existing between L.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 9:00

Claims (9)

[Claims] 1. At least a thermoplastic resin film, a high density foam made of polystyrene resin and a low density foam are laminated in this order, and the high density foam is at least 200 μm from the interface with the thermoplastic resin film. 0.8-0.11 g / cm ³ density and 5-250 μm
The low density foam has a cell size of 0.22 to 0.22.
A polystyrene-based resin laminated foam sheet having a density of 0.047 g / cm ³ and having a total thickness of the high-density foam and the low-density foam of 0.7 to 4.0 mm. 2. The sheet according to claim 1, wherein at least one of the high-density foam and the low-density foam contains a filler in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the polystyrene resin. 3. The sheet according to claim 1, wherein at least one of the high density foam and the low density foam is made of a heat resistant polystyrene resin. 4. The sheet according to claim 1, wherein at least one of the high density foam and the low density foam contains a rubber component. 5. The sheet according to claim 1, wherein the thermoplastic resin film has a gas barrier property. 6. The sheet according to claim 1, wherein at least one of the high density foam, the low density foam and the thermoplastic resin film is partially colored. 7. A molded product obtained from the sheet according to claim 1. 8. A thermoplastic resin for forming a thermoplastic resin film and 0.8 to 0.11 g / cm ³ at least 200 μm from the interface between the thermoplastic resin film and the thermoplastic resin.
And a polystyrene resin containing a foaming agent for forming a foam layer having a cell size of 5 to 250 μm,
Polystyrene resin containing a foaming agent for forming a foam having a density of 0.22 to 0.047 g / cm ³ is heated and melted by an extruder, respectively, and laminated inside or outside a molding die. A method for producing a polystyrene-based resin laminated foam sheet, comprising: 9. A polystyrene resin containing a foaming agent for forming a foam layer having a density of 0.8 to 0.11 g / cm ³ and a cell size of 5 to 250 μm at least 200 μm from the interface of the thermoplastic resin film. And 0.
Polystyrene resin containing a foaming agent for forming a foam having a density of 22 to 0.047 g / cm ³ is melted by heating with an extruder, and laminated inside or outside a molding die to form a laminated foam sheet. The method for producing a polystyrene-based resin laminated foam sheet, comprising laminating a thermoplastic resin film on the low-density foam side of the laminated foam sheet.