JP3530673B2 - Polystyrene resin foam laminated sheet, method for producing the same, and molded product thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene resin foam laminated sheet, a method for producing the same, and a molded article using the foam laminated sheet as a material, more specifically, a high density foam sheet and a low density foam sheet. The present invention relates to a polystyrene-based resin foam laminated sheet having a layered structure, a method for producing the same, and a molded article having the high-density foam sheet side as an inner surface.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining a polystyrene-based resin foam-molded article, a polystyrene-based resin foam sheet is heated in a molding machine to be secondarily foamed to be in a softened state and molded and punched or molded by various molding methods. Punching is being done at the same time. In addition, various methods have been attempted in order to obtain strength, which is one of the required functions of a molded product. For example, the molded product may be made thicker or heavier, or the molded product may be provided with a plurality of ribs. It is installed.

That is, in many cases, a tray container or the like is filled with the contents in a container, wrapped with a film, and lined up in a store in the state of being wrapped. In such a tray container usage method, since a large compressive force is applied to the container,
In order not to be deformed by this compressive force, it is necessary for the container to have a compressive strength sufficient to withstand these forces and at the same time a function of not easily buckling. In addition, it is also necessary that the wrapped state of the wrapped film can be maintained for a long time, and for that reason, it is also necessary that the film can withstand the compressive strength for a certain period of time or longer.

As one method of imparting such a function to a polystyrene-based resin foam-molded article while saving material,
It has been proposed that only the inside of the molded product has a high-density skin layer (see Japanese Utility Model Publication No. 63-6005). In a container such as a tray, when lapping is performed, a compressive stress is generated inside the boundary between the side wall and the bottom, while a tensile stress is spread outside in a wide range from the side wall to the bottom. Therefore, by forming a high-density skin layer only on the inner side of the molded product, it is intended to impart resistance to the extreme compressive stress generated on the inner surface.

[0005]

The above proposal is effective for imparting the necessary strength to the polystyrene resin foam molded article, but this method is achieved by blowing air on the surface of the foam sheet. Since the high-density skin layer is formed, the thickness of the high-density layer is limited to about 0.05 mm at the maximum in consideration of moldability and the like. Since it may not always be sufficient, it is necessary to attach additional ribs.

If a reinforcing rib is provided, it may not be possible to form a deep container due to its moldability. Also, when a tray or the like is formed, depending on the shape, the stacking height of molded products (for transporting the container, However, the bulkiness when superposed) cannot be lowered, which causes a problem of bulkiness.

An object of the present invention is to solve the above-mentioned inconveniences of conventional polystyrene resin foamed sheets and molded products thereof, and more specifically, the foamed sheet as a whole has the same thickness and the same thickness. It is possible to obtain a molded product with higher strength (particularly rib compression strength), which is similar to a molded product molded using a polystyrene-based resin foam sheet with high density, thereby saving material and reducing costs. It is an object of the present invention to obtain a polystyrene-based resin foam sheet capable of achieving the above, a method for producing the same, and a molded product thereof.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present inventors have conducted many experiments and studies on a polystyrene-based resin foam sheet and a molded product thereof, and as a result, basically, a polystyrene-based resin foam The sheet has a two-layer structure of at least a high-density foam sheet layer and a low-density foam sheet layer, and the high-density foam sheet has an average cell diameter of 30 μm or more and an average number of cells in the thickness direction of 3 or more. The inventors have found that the above object can be achieved by molding a molded article such as a container with the high-density foamed sheet side of the foamed laminated sheet being the inner side, and have completed the present invention.

Further, if the foamed laminated sheet of the present invention has the same basis weight and the same density as the conventional polystyrene resin foamed sheet, not only the strength but also the molding elongation at the time of molding is very high as compared with the foamed sheet. I found it to be good.

That is, the present invention is a polystyrene resin foam laminated sheet, wherein the foam laminated sheet comprises a high density foam sheet and a low density foam sheet laminated, and the high density foam sheet has a density of 0.7 g / cc to 0.13 g / cc, thickness 0.2 mm to 2.8 mm, average cell diameter 30 μm or more, and an average of 3 or more cells arranged in the thickness direction, and the low-density foamed sheet has a density of 0. 22g / cc ~
0.042 g / cc and a thickness of 3.0 mm or less,
A polystyrene-based resin foam laminated sheet, wherein the total thickness of the high-density foamed sheet and the low-density foamed sheet is in the range of 0.7 to 3.5 mm, and a molded article using the polystyrene-based resin foamed laminated sheet. Then, the high-density foamed sheet is formed inside the molded product, and the thickness of the high-density foamed sheet at the boundary portion between the side wall portion and the bottom portion is set in the range of 0.2 mm to 3.0 mm. The main point is a molded product.

The polystyrene resin foam laminated sheet of the present invention has a basic structure of a laminated structure of at least a low density foam sheet and a high density foam sheet. As the polystyrene resin constituting the polystyrene resin foam laminated sheet of the present invention, styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, vinylxylene alone Examples thereof include a polymer and a copolymer. Examples of the copolymer include styrene-maleic anhydride copolymer, styrene-acrylic acid polymer, high-impact polystyrene, styrene-acrylonitrile copolymer, polystyrene resin such as acrylonitrile-butadiene-styrene copolymer. .

The high density foamed sheet constituting the polystyrene resin foam laminated sheet of the present invention has a density of 0.7 g / c.
c to 0.13 g / cc, the thickness from the surface of the foamed sheet is 0.2 mm to 2.8 mm, and the average cell diameter in that portion is 30 μm or more, preferably 30 μm to 250 μm.
And the number of cells in the thickness direction is 3 or more.

High density foam sheet has a density of 0.7 g / cc
If it exceeds, it is difficult to extrude the high-density foamed sheet and the low-density foamed sheet by coextrusion, which is not preferable,
Also, it becomes almost like a film, and when compressive stress is applied to the inner surface of the container, the high-density foamed sheet easily breaks at the poles,
As a result, the bubbles on the side of the low-density foamed sheet are buckled, and the bending strength is reduced. When the density is less than 0.13 g / cc, secondary foaming becomes large when the molded product is obtained by heat molding, and the density of the molded product after molding exceeds 0.07 g / cc. It is not preferable because the effect of preventing the buckling of the poles of the product becomes small.

When the thickness of the high-density foamed sheet is less than 0.2 mm, when the polystyrene-based resin foamed laminated sheet of the present invention is molded into a molded product, the thickness of the boundary portion between the side wall and the bottom of the molded product. May be stretched to less than 0.2 mm during molding, and the buckling prevention effect is reduced.

According to the experiments conducted by the present inventors, when the density of the high density foamed sheet is 0.13 g / cc or less, heating is performed using the foamed laminated sheet of the present invention except for a shallow mold product such as a tray. The thickness of the boundary portion between the side wall portion and the bottom portion of the molded product obtained by molding was stretched at the time of molding and became thinner than necessary, and the buckling prevention effect intended by the present invention was not good.
Further, even if the thickness exceeds 2.8 mm, the merit is lost without increasing the buckling prevention effect. The effect of the bubble diameter on the strength is also large, the average bubble diameter is 30 μm or more, preferably 30 μm to 250 μm, and if the number of bubbles in the thickness direction is 3 or more, the buckling prevention effect is large, and the thickness of the high density foamed sheet is It turns out that 0.2 mm is enough. However, if the bubble diameter is less than 30 μm, the strength is low.

The low density foam sheet constituting the polystyrene resin laminated foam sheet of the present invention has a density of 0.22 g /
It is in the range of cc to 0.042 g / cc and the thickness is 3.0.
mm or less. The total thickness of the high-density foamed sheet and the low-density foamed sheet laminated is 0.7 to 3.5 m.
m.

Low density foam sheet has a density of 0.22 g / c
If it exceeds c, the tensile strength will be more than required to overcome the tensile stress of the molded product after molding, and the economical efficiency will decrease. Also, the density of the low-density foamed sheet is 0.042 g / c.
If it is less than c, air bubbles are often communicated during the production of a laminated foam sheet of a high-density foam sheet and a low-density foam sheet by coextrusion, resulting in poor elongation at the time of molding to obtain a molded product and crevices. To do. Furthermore, because of the communication of air bubbles, the strength of the molded product is weakened and partial heating unevenness is likely to occur during heating in the molding machine at the time of molding, thus narrowing the range of molding conditions. When coextruding, the density of 0.042 g / cc is the limit on the stability of extrusion.

If the total thickness of the high-density foamed sheet and the low-density foamed sheet laminated is less than 0.7 mm, the strength will be insufficient when molded. That is, the bending strength is the same as that of a general expanded polystyrene sheet, and there is little merit. Further, if the total thickness exceeds 3.5 mm, even if the container is molded in combination with a high-density foamed sheet, only bending strength equivalent to that of a general foamed polystyrene sheet can be obtained, and there is little merit. Therefore, the thickness of the low-density foamed sheet in the present invention is 3.0 mm or less, particularly 0.2 mm to 2.8.
mm is preferably used.

In the present invention, a thermoplastic resin film may be laminated on at least one surface of the polystyrene resin laminated foam sheet of the present invention. Further, other foam may be laminated. For example, three-layer structure of thermoplastic resin film / high-density foam sheet / low-density foam sheet, thermoplastic resin film / high-density foam sheet / low-density foam sheet / four-layer structure of thermoplastic resin film, thermoplastic resin film / Examples include a combination of a high-density foamed sheet / low-density foamed sheet / high-density foamed body / thermoplastic resin film having a five-layer structure. If a thermoplastic resin film is attached to the low-density foamed sheet side, a function of suppressing the elongation of the entire skin layer against tensile stress can be imparted, and the strength of the foamed sheet is improved. In this case, the high density foamed sheet / low density foamed sheet / thermoplastic resin film is used. In the present invention, a laminated body of a combination of a low density foam sheet / high density foam sheet / high density foam sheet may be used.

The present invention further provides a molded product using the foamed laminated sheet, wherein the high-density foamed sheet is the inside of the molded product, preferably at the boundary between the side wall and the bottom of the molded product. Also disclosed is a molded article in which the high-density foamed sheet has a thickness of 0.2 mm or more, more preferably 0.2 mm to 3.0 mm.

The molded product of the present invention has a high-density foamed sheet inside and therefore has excellent strength. Using the polystyrene-based resin laminated foam sheet of the present invention,
When a container such as a tray is obtained by molding using a conventional molding machine, it does not deform due to the force of the wrap even if it is wrapped with a film and left for a long time, and it does not buckle easily. There is. Further, since the molded product provided with the reinforcing rib has good elongation of the polystyrene-based resin laminated foam sheet of the present invention,
Despite the container having a larger depth than the caliber, it is strong and has a uniform thickness. And even if the molded products are stacked, the bulk is not bulky.

Any of the thermoplastic resin films used in the present invention can be used as long as it has the physical properties of being stretched by heat molding when molding the laminated foam sheet of the present invention. , Styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, vinylxylene homopolymer or copolymer, for example, styrene-maleic anhydride copolymer as resin Polymers, styrene-acrylic acid copolymers, impact polystyrene, styrene-acrylonitrile resins, acrylonitrile-butadiene-styrene resins can be used. Particularly, polystyrene resin and high impact polystyrene resin are preferable. In addition, a mixture of polystyrene-based resin and high-impact polystyrene is used, or high-impact polystyrene is used alone, and the high-impact polystyrene has a styrene-butadiene copolymer dispersed in a salami structure and has a particle size of 0. A large amount of those having a thickness of 3 μm to 10 μm can be mentioned.

Further, linear low density polyethylene, high density polyethylene, low density polyethylene, propylene homopolymer, ethylene-propylene random polymer, ethylene-propylene block polymer, ethylene-propylene-butene-terpolymer, ethylene-vinyl acetate copolymer. Polymers, 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 copolymer) polyethylene or polypropylene Unsaturated carboxylic acid (for example, maleic anhydride) modified product, ethylene-
Propylene rubber, atactic polypropylene and the like, polyethylene, ethylene-propylene copolymer,
Examples thereof include a propylene-butene-1 copolymer, a mixture of two or more kinds thereof, and films such as polyethylene terephthalate and polybutylene terephthalate.

Further, it is also a preferable embodiment to laminate a thermoplastic resin film having a gas barrier property. Examples of the film having the gas barrier property include ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyvinylidene chloride, polyamide, Polyester, polyacrylonitrile, vinylidene chloride-based acrylonitrile copolymer, acrylonitrile-based methyl methacrylate-butadiene copolymer, nylon, biaxially stretched nylon, biaxially stretched polyethylene terephthalate, biaxially stretched polypropylene, high density polyethylene, ionomer resin ( For example,
(Registered trademark Surlyn) or a metal vapor-deposited film, and these may be used alone or as a laminate of these films.

In the present invention, in laminating the high density foamed sheet or the low density foamed sheet and the thermoplastic resin film, a laminating method using heat may be used in addition to the coextrusion method. In that case, the thermoplastic resin film is thermocompression-bonded by the hot roll from the opposite side of the joining surface. In this case, the surface of the roll to be heat-pressed is subjected to chrome plating or Teflon coating to prevent stickiness with the heated thermoplastic resin film. Further, the joint surface may be heated by a heating device together with the thermocompression bonding using a hot roll.

Further, the high density foamed sheet and the low density foamed sheet, or the high density foamed sheet or the low density foamed sheet and the thermoplastic resin film may be bonded together by using an adhesive or an adhesive layer. The adhesive used at this time is preferably an adhesive such as an ethylene-vinyl acetate copolymer, a methyl methacrylate polymer elastomer (Tufrene, Tuftec: Asahi Chemical Industry Co., Ltd.), and the thickness thereof is 5 μm to Used at about 150 μm.

The thickness of the thermoplastic resin film used in the present invention is 10 μm to 500 μm, preferably 15 μm.
˜300 μm. If it is less than 10 μm, the bottom is limited, and if it is less than 10 μm, perforation may occur in the thermoplastic resin film when molded into a container. In addition, the current extrusion technology is 5
A limit of about μm is a stable limit. On the other hand, the thickness is 5
If it is thicker than 00 μm, the polystyrene-based resin foam sheet may be burnt or peeled during lamination. Moreover, since it cannot be produced by coextrusion, it is disadvantageous from the viewpoint of manufacturing cost.

Incidentally, a pigment such as titanium oxide may be mixed in the thermoplastic resin film in an amount of 5 parts by weight or less with respect to 100 parts by weight of the raw material at the time of film production. Further, the thermoplastic resin film, the high-density foam sheet and the low-density foam sheet,
It may be colored in advance with a coloring agent or the like. Further, by printing on a thermoplastic resin film in advance and laminating the printed surface inside, a molded product having a glossy appearance and a beautiful surface can be obtained.

Next, a method of manufacturing the polystyrene resin laminated foam sheet of the present invention will be described. In addition, in the present invention, in order to obtain a foamed sheet having a desired density, the types and amounts of the foaming agent and the additive and the foaming temperature are appropriately adjusted.

First, the high density foamed sheet and the low density foamed sheet can be formed by a known extrusion foaming method. The extrusion foaming method is carried out by adding a base resin, a foaming agent and additives necessary for foaming to an extruder so as to obtain a desired density, melt-kneading, and then extruding from a die of the extruder. The base resin, the foaming agent and the additive may be uniformly mixed in advance and then supplied to the extruder. In addition, the additive is
A so-called master batch may be prepared by adding a resin of the same type as the base resin in high concentration in advance.

As the foaming agent that can be used in the present invention, any known foaming agent can be used.
There are gaseous or volatile blowing agents. Examples of the decomposition-type foaming agent include ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, calcium azide, sodium azide, inorganic decomposable foaming agents such as sodium borohydride, azodicarbonamide, azobissulfolumamide, Azo compounds such as azobisisobutyronitrile and diazoaminobenzene, N, N'-dinitrosopentane methyleneteloramine and N, N'-dimethyl-
Nitroso compounds such as N, N'-dinitrosoterephthalamide, benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide and p, p'-oxypisbenzenesulphonyl semicarbazide, p-toluenesulfonyl semicarbazide, trihydrazinotoeazine, barium Azocarboxylate etc. are mentioned. These foaming 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, n-butane, i-butane, methyl ether and the like can be mentioned. The gas here is normal temperature (25 ° C),
It means that it is a gas at normal pressure (1 atm). On the other hand, examples of the volatile foaming agent include ether, petroleum ether, acetone, pentane, isopentane, hexane, isohexane, heptane, isoheptane, benzene and toluene. You can also use water. These can be mixed and used.

Of the above foaming agents, butane is preferred. When it is desired to reduce the bubble size to about 40 μm or less, nitrogen, carbon dioxide gas, or water is preferably used or used in combination.
Further, nitrogen and the like can be directly separated from the air, which is advantageous in that it is inexpensive.

Examples of the additives necessary for foaming include a cell regulator and the like. Specific examples 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. If you increase the amount of these foam regulators,
The bubble film becomes vulnerable to heat, and the bubble film may break during extrusion lamination, resulting in large bubbles. 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, etc. may be added. The melt-kneaded resin is directly extruded into a sheet shape or a cylindrical shape from a die whose temperature is most suitable for foaming, and then cut into a sheet shape by cutting at an arbitrary line.

Here, when a high-density foamed sheet is produced, it depends on the type of extruder and resin used, etc.
The extruder barrel temperature is maintained at about 140-260 ° C.
Further, the foaming agent was added to 100 parts by weight of the base resin.
It is preferable to add 07 to 3.3 parts by weight, and 0.01 to 7.0 parts by weight of the cell regulator.

On the other hand, when producing a low-density foamed sheet,
The extruder barrel temperature is maintained at about 140 to 260 ° C., though it depends on the type of extruder and resin used. Further, the foaming agent is 0.5 to 100 parts by weight of the base resin.
It is preferable to add 7.0 parts by weight, and 0.01 to 5.0 parts by weight of the cell regulator.

Next, the thermoplastic resin film is melted with a film raw material (comprising 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 a film from a screw die or the like). The high-density foamed sheet and the low-density foamed sheet thus obtained are obtained by the coextrusion method,
They may be laminated by a known method such as a laminating method using an adhesive or a fusion bonding 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 coextrusion method, it is preferable to extrude the high density foamed sheet inside (plug side) and the low density foamed sheet outside. This is because when the low-density foamed sheet is placed inside, bubbles may be crushed by the plug, which makes it difficult to adjust the thickness and density of the foamed sheet.

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 foamed sheet or the low-density foamed sheet with a hot roll and / or hot air, and then the low-density foamed sheet or the high-density foamed sheet is laminated. Is. It is preferable that the surface of the heat roll is plated with chrome or Teflon to prevent stickiness with the heated foam sheet.

The polystyrene-based resin foam laminated sheet of the present invention is preferably obtained by a coextrusion method. The polystyrene-based resin foam laminated sheet obtained by the co-extrusion method is excellent in economic efficiency and has a wide product specification range of the foam laminated sheet.
There are advantages such as excellent moldability. The method of bonding the high-density foamed sheet and the low-density foamed sheet after molding requires an additional bonding step and is inferior in economic efficiency, and the thickness obtained by extrusion of the high-density foamed sheet or the low-density foamed sheet is 250 μm or less. Is difficult
In addition, it is difficult to control the stretching, and there is a problem that the elongation during molding remains a problem. In addition, when the thickness of the polystyrene-based resin foam laminated sheet to be obtained is small, that is, when the high-density foam sheet and / or the low-density foam sheet is thin, the foam sheet may shrink due to heat during bonding. In addition, since the stretching cannot be controlled even if they are stuck together with an adhesive or the like, the resulting foamed laminated sheet has poor elongation at the time of molding, resulting in poor moldability. In the case of the co-extrusion method, the above inconvenience can be easily avoided.

When the bonding method is used, the boundary surface between the high density foam sheet and the low density foam sheet can be clearly seen, but when coextrusion is used, the boundary surface may be unclear.

When laminating a thermoplastic resin film, it may be co-extruded with the above-mentioned foam sheet, and the thermoplastic resin film and the high-density foam sheet (or low-density foam sheet) are co-extruded, and then the low-density foam sheet (or High density foamed sheets) may be laminated by a laminating method or a fusion bonding method using an adhesive. When the thermoplastic resin film is attached using an adhesive, the thickness of the adhesive is added to the film thickness.

Further, air may be blown onto the surface of the high density foamed sheet and / or the low density foamed sheet to form a skin on the surface of the foamed sheet. At that time, preferably air of 5 ° C. to 80 ° C., preferably 5 ° C. to 45 ° C. (air ring inlet air temperature) is applied to the high density foamed sheet side at 0.04 m ^{3 to} 0 per 1 m ² of the foamed sheet. .4m
³ spraying, 5 ° C. to 80 ° C. The low-density foam sheet side, preferably so that the air 5 ° C. to 45 ° C. giving 1 m ² per 0.02 m ³ ～0.3M ³ blown foam sheet. When the foamed sheet is extruded in a single layer and laminated after extrusion, the foamed sheet may be laminated with a skin by blowing air on one side and / or both sides in the same manner. By forming the skin in this way, the appearance can be made clean, the printability can be improved, and
The effect of improving the strength of the rib is brought about.

[0046]

EXAMPLES The present invention will be described below with reference to examples. 5 to 15 parts by weight as a cell regulator in 100 parts by weight of polystyrene resin
0.6 to 3.0 parts by weight of powder of talc of μm is added, or these are added by a masterbatch, and this is added with an inner diameter of 90
The mixture was put into a batch type continuous mixing device on a hopper of an extruder having a size of mm to 150 mm, uniformly mixed, and then supplied from the hopper to the extruder. The maximum cylinder temperature of the extruder was 230 ° C, and butane gas (i-butane 6) was used as the foaming agent.
5%, n-butane 35%) and about 1.0 to 3.5% by weight of carbon dioxide gas and 0 to 2% by weight of carbon dioxide were added to the merging die at a rate of 60 to 80 kg / hour.

On the other hand, 0.4 to 1.5 parts by weight of talc powder having a particle size of 5 to 15 μm as a cell regulator based on a polystyrene resin having a melt index (referred to as MI value) different from that of the polystyrene resin and a trade name: Hydrocerol CF-40S (manufactured by Dainippon Seika Kogyo Co., Ltd.) 0.2
~ 1.0 parts by weight and 2 parts of color masterbatch (20% kneading) were added, and this was put into a batch type continuous mixing device on the hopper of an extruder having an inner diameter of 90 mm to 150 mm,
The mixture was uniformly mixed and fed from the hopper to the extruder. The cylinder temperature of the extruder was set to a maximum setting temperature of 245 ° C, and butane gas (i-butane 60%, n-butane 40%) was used as a foaming agent.
%) Was added to the joining die in balance with the extruder for extruding the high-density foamed sheet.

The two kinds of resin mixed together by the combining die are flown into a mold having a diameter of 126 mm, and immediately after being extruded into a cylindrical shape through a slit, air is blown inside and outside the balloon to cool the foamed sheet. Then, a polystyrene-based resin foamed laminated sheet of the present invention was obtained, and this foamed laminated sheet was evaluated and used as an example.

[Example 1] MI value 4.1 (catalog value)
Polystyrene resin (trade name: Denkastyrol HRM
-5: manufactured by Denki Kagaku Kogyo Co., Ltd.) 0.8 part by weight of talc powder having a diameter of 5 to 15 μm was added to 100 parts by weight as a cell adjuster, and this was continuously mixed in a batch on a hopper of an extruder having an inner diameter of 90 mm. After being charged into the apparatus and uniformly mixed, the mixture was supplied from the hopper to the extruder. The maximum cylinder temperature of the extruder was 230 ° C., butane gas (i-butane 65%, n-butane 35%) was added as a foaming agent in an amount of about 2.5% by weight, and the mixture was flown into the joining die at a rate of 76 kg / hour. .

On the other hand, a polystyrene resin having an MI value of 1.9 (catalog value) (trade name: Denkastyrol HRM-2:
100 parts by weight of Denki Kagaku Kogyo Co., Ltd., 0.8 parts by weight of talc powder of 5 to 15 μm as a cell adjuster, and trade name: Hydrocerol CF-40S (manufactured by Dainippon Seika Kogyo Co., Ltd.). 6 parts by weight is added, and the inner diameter is 90 mm.
Charge into the batch type continuous mixing device on the hopper of the extruder,
The mixture was uniformly mixed and fed from the hopper to the extruder. The maximum cylinder temperature of the extruder is 245 ° C, butane gas (i-butane 60%, n-butane 40%) is used as a foaming agent.
Was added to the merging die at a rate of 77 kg / hour.

The two kinds of resin mixed together by the combining die are flown into a mold having a diameter of 126 mm, and immediately after being extruded into a cylindrical shape through a slit, air is blown inside and outside the balloon to cool the foamed sheet. did. Air temperature is 27 ℃
, And the amount sprayed, the inside of the high density foam sheet side 0.10 m ³ / m ^2, the outside of the low-density foam sheet side was 0.07m ³ / m ^2.

The high density foamed sheet of this foamed laminated sheet has a thickness of about 0.5 mm and a basis weight of 106 g / m ² (density 0.21).
2 g / cc) and the thickness of the low-density foam sheet is about 1.9.
mm, weighing 104 g / m ² (density 0.055 g / cc)
Met. That is, the total thickness of the obtained foam laminated sheet was 2.4 mm, and the basis weight was 210 g / m ² . The average bubble diameter of the high density foamed sheet is 71 μm,
It was calculated that there were 7.0 bubbles on average in the thickness direction.

The thickness of the foamed sheet was measured by a micrograph, and the basis weight was measured by taking 10 1 cm squares from the foamed sheet and dividing them into high density and low density with a razor.
The density was calculated from the basis weight and the thickness. If either the high-density foamed sheet or the low-density foamed sheet is colored, it will be easy to separate and the work will be facilitated.

The average cell diameter D is obtained by cutting a high-density foamed sheet into a cross in the flow (MD) direction, the length in the thickness direction is L, and the number of cells between L (excluding skin) is N. It is represented by D = L / N, and shows the average diameter of bubbles existing between L. The number of bubbles between the Ls was similarly measured with a micrograph.

This foamed laminated sheet stock was measured to have a size of 195
(Length) x 120 (width) x 25 (height) mm using a mold, single-shot molding machine (Sekisui Plastics industrial specifications), oven temperature about 280 ℃ ~ 350 ℃, mold clamping time about 3.5 seconds It was molded in. Thickness (mm) of the side, bottom and boundary of the molded product
Was measured with a micrograph. Also, the rib compression strength is A
Using a load measuring machine Model 1310DS manufactured by IKOH ENGINEERING, the repulsive force when the molded container was compressed by 10 mm (400 mm / min) was measured. Furthermore, about 300 μm was sliced on the high-density foamed sheet side of the molded product, and the density was measured. The measured values are shown in Table 1.

[Examples 2 to 4 and Comparative Examples 1 to 7] Foamed laminated sheets were obtained in the same manner as in Example 1 and molded in the same molding die size as in Example 1 and evaluated by the same molding machine. At that time,
The total thickness of the foamed laminated sheet and the weight as a whole are substantially the same as those in Example 1, and the thickness and basis weight of each of the high-density foamed sheet and the low-density foamed sheet are adjusted by adjusting the discharge rate of the extruder. To make it different. However, Example 2
For the low density side of, the resin used by re-pelletizing the used tray on the market was used (MI value 6.7). Further, Comparative Example 7 is a case where a low-density foamed sheet has a single-layer structure.

Each value was measured in the same manner as in Example 1. The measured values are shown in Table 1 together with the values of Example 1.
Shown in. Looking at Examples 1 to 4 and Comparative Examples 1 to 7, although the thickness and the weight (hence, the density) of the foam laminated sheet are almost the same, those of the comparative example, that is, the foam laminated sheet of the present invention. Those that do not satisfy any one or more of the above-mentioned conditions all show a rib compression strength lower than that of the examples, indicating the superiority of the present invention.

In particular, in Comparative Example 1, the thickness of the high-density foamed sheet was too thin, so that the thickness of the boundary portion between the side and bottom of the molded article was thinned, and the number of bubbles existing in the thickness direction of the high-density foamed sheet. Buckling also occurred due to the small number. In Comparative Example 2, since the high-density foam sheet was thin and had a high density, and the number of bubbles existing in the thickness direction of the high-density foam sheet was small, the strength also decreased and buckling occurred. In Comparative Example 4, since the density of the low-density foamed sheet was too small, the communication of air bubbles was large and the rib strength was significantly reduced. Furthermore, in Comparative Examples 5 and 6, it can be understood that the rib strength was lowered due to the fact that the average bubble diameter of the high-density foamed sheet was small and the bubbles were fine.

When the foamed laminated sheet of Example 1 was molded so that the low-density foamed sheet was on the inside of the container, the rib compressive strength of the container decreased to 640 g. From these facts, when comparing with the same thickness and the same weight, if the thickness of the foamed sheet on the high density side (inside the molded product) is 0.2 mm or more, the case of a multilayered sheet compared with a single layer foamed sheet It can be seen that the strength is greatly increased.

[0060]

[Table 1]

[Examples 5 to 7 and Comparative Examples 8 to 9] Example 1
A foamed laminated sheet was obtained in the same manner as in. At that time, similarly, the thickness and basis weight of each of the high-density foamed sheet and the low-density foamed sheet were made different by adjusting the discharge rate of the extruder. However, the total thickness of the foamed laminated sheet is in the same range of 3.1 mm to 3.5 mm, and the basis weight as a whole is 301 g / m ^{2 to} 308 g / m.
^The range of ² is almost the same. In Comparative Example 9, a low-density foamed sheet has a single-layer structure.

Using these original fabrics, the size 162 (length)
A box-shaped container of × 132 (width) × 54 (depth) mm was molded in the same manner as in Example 1, and each value was measured and evaluated in the same manner as in Example 1 for each. The results are shown in Table 2.

Looking at Examples 5 to 7 and Comparative Examples 8 to 9, the thickness and basis weight (and hence the density) of the foamed sheet are almost the same in this case as well, but all of the Comparative Examples are the same. The rib compressive strength shows a value lower than that of the examples, which shows the superiority of the present invention. Particularly, in Comparative Example 8, the bending strength was the same as the bending strength of the general PSP because the low-density foam sheet was too thick.
Moreover, the mold was not well-defined and the growth was insufficient.

[Examples 8 to 10 and Comparative Examples 10 to 11] In the same manner as in Example 1, foamed laminated sheets were obtained. Also in this case, the thickness and basis weight of the high density foamed sheet and the low density foamed sheet were made different by adjusting the discharge rate of the extruder. The foamed laminated sheet had a total thickness of 2.15 mm to 2.4 mm in substantially the same range, and a total basis weight of 210 g / m ^{2 to} 214 g / m ^{2 in} the substantially same range.

Further, in Example 8, an OPS film (100 μm thick) was laminated on the high-density foamed sheet side by a hot roll. In Example 9, a HIPS film (100 μm thick) was laminated on the low density foam sheet side by an extrusion method.

In Example 10, Sumilite CEL (manufactured by Sumitomo Bakelite Co., Ltd.) (80 μm thick), which is a commercially available barrier film, was laminated on the high-density foamed sheet side with a hot roll. In Comparative Example 10 and Comparative Example 11, a HIPS film (about 100 μm) was laminated on the low density foam sheet side by an extrusion method.

Using these original fabrics, size 162 (length)
A box-shaped container of x132 (width) x 54 (depth) mm was molded in the same manner as in Example 1, and each value was measured and evaluated in the same manner as in Example 1 for each. The results are shown in Table 2.
Shown in.

Looking at Examples 8 to 10 and Comparative Examples 10 to 11, the thickness and basis weight (and hence the density) of the foamed sheet are almost the same in this case as well, but all of the Comparative Examples are the same. The rib compressive strength shows a lower value than that of the example, which also shows the superiority of the present invention. In particular, in Comparative Example 10, as in Comparative Example 2, the high-density foamed sheet was thin and had a high density, and the number of bubbles existing in the thickness direction of the high-density foamed sheet was small, so that the strength also decreased. Then, the bubbles on the side of the low-density foamed sheet were destroyed and buckling occurred. In addition, in Examples 8 to 10, since the films were laminated, the molded products having the same dimensions as those of Examples 5 to 7 showed high rib compressive strength.

[Example 11] 95 parts by weight of a heat-resistant polystyrene resin having an MI value of 4.1 (trade name: Asahi Kasei Polystyrene G9001: Asahi Kasei Kogyo Co., Ltd.): an elastomer resin having an MI value of 13 (trade name: Tuffprene A: Asahi Kasei Kogyo Co., Ltd.) To 5 parts by weight, 0.6 parts by weight of talc powder having a particle size of 5 to 15 μm as a cell adjuster was added to 100 parts by weight of the resin, and this was supplied to an extruder having an inner diameter of 90 mm in the same manner as in Example 1. The extruder cylinder temperature was set to a maximum setting temperature of 265 ° C, and butane gas (i-butane 35%, n-
Butane 65%) was added to about 3.1% by weight to obtain 76 kg / Hr.
It flowed into the merge die at a rate of.

On the other hand, 100 parts by weight of a heat-resistant styrene resin having an MI value of 1.4 (trade name: Asahi Kasei Polystyrene G9001: Asahi Kasei Kogyo Co., Ltd.) is used as a cell adjuster in an amount of 5-1.
0.8 parts by weight of 5 μm talc powder and 20 parts of tuckle powder
Parts by weight and 5 parts by weight of calcium stearate and 2 parts by weight of a masterbatch of impact resistant resin,
This was fed to an extruder having an inner diameter of 90 mm to 150 mm in the same manner as in Example 1.

The maximum cylinder temperature of the extruder is 2
75 ° C., butane gas (i-butane 65
%, N-butane 35%) was added by a separate diaphragm type high pressure pump in an amount of about 6.1% by weight, and the mixture was flown into the merging die at a rate of 78 kg / Hr. The two kinds of resin mixed together by the combining die were flown into a mold having a diameter of 120 mm, and immediately after being extruded into a cylindrical shape from a slit, air was blown inside and outside the balloon to cool the foamed sheet. Air temperature was 31 ° C., the amount sprayed is, 0.12 m ³ / m ² on the inside of the high density foam sheet side, the outside of the low-density foam sheet side was 0.08m ³ / m ^2.

This foam sheet is a high density foam sheet having a thickness of about 0.8 mm and a basis weight of 112 g / m ² (a density of 0.14).
g / cc), and the low-density foam sheet has a thickness of about 1.6 m
m, and the basis weight was 101 g / m ² (density 0.063 g / cc). That is, the total thickness of the foamed sheet was 2.4 mm, and the basis weight was 213 g / m ² . The average cell diameter of the high-density foamed sheet was 221 μm, and it was calculated that there were 3.6 cells on average in the thickness direction.

On the side of the high-density foamed sheet of this two-layer foamed laminated sheet, a resin of which the Asahi Kasei polystyrene G9001 having an MI value of 1.4 and Toughprene A (MI value of 13) were mixed in a ratio of 9: 1 to form a pellet having a size of 90 mm was used. The cylinder maximum temperature was 280 ° C. with an extruder, and a film of about 100 μm was extrusion laminated using a T die. Using this laminate stock,
Dimension 162 (length) so that the high density side is on the inside x
A box-shaped container of 132 (width) × 54 (depth) mm was molded. Molding was performed at a molding temperature of about 300 to 380 ° C. and a mold clamping time of 4.9 seconds.

In the same manner as in Example 1, the thickness of the side part, the bottom part and the boundary part of the molded product was measured by a micrograph. The rib compressive strength was also measured. Table 2 shows those values.
It was shown to. In this case, since the film was attached to the low density side in Example 9, the increase in the force against the local compressive stress generated on the inner surface of the container was small, and the laminated barrier film used in Example 10 was the same as Example 11. Since it is softer than the film of Example 9, although it is a molded product of the same size as in Example 9,
The rib compressive strength is higher than those of Nos. 10 to 10.

[0075]

[Table 2]

[Examples 12-14, Comparative Examples 12-14]
A foam laminated sheet was obtained in the same manner as in Example 1. At that time, the thickness and the density of the high-density foamed sheet and the thickness and the density of the low-density foamed sheet were made substantially equal to each other, and the high-density foamed sheet was molded so that only the average cell diameter was different. Using these stocks, size 1
A container of 62 (length) × 132 (width) × 54 (height) mm was molded in the same manner as in Example 1, and each value was measured and evaluated in the same manner as in Example 1 for each. The results are shown in Table 3.

The rib strength of the comparative example is lower than that of the example, even though it is a molded article made from the foamed laminated sheet having a substantially identical two-layer structure. this is,
In Comparative Example 12, the average cell diameter was 85 μm with respect to the thickness of the high-density foamed sheet of 0.23 mm, and the number of bubbles present in the thickness direction of the high-density foamed sheet was 2.7, which was small, and in Comparative Example 13, High density foam sheet thickness 0.28m
The average bubble diameter is 23 μm with respect to m, and it is considered that this is because the bubble diameter is too small. Comparative Example 1
No. 4 is a low-density foam sheet single layer, and its strength is also lowered.

[Examples 15 to 16 and Comparative Examples 15 to 16]
When the foamed laminated sheets shown in Examples 15 to 16 and Comparative Examples 15 to 16 in Table 3 were used to mold a cup of 95 (caliber) mm x 65 (depth) mm while adjusting the clearance of the mold, The foamed laminated sheets of Examples 15 and 16 and Comparative Example 15 could be molded, but the foamed laminated sheets of Comparative Example 16 were difficult to mold. Next, 95 (caliber) mm x 8
When a cup having a depth of 5 mm was molded, the laminated foam sheet of Example 15 could be molded, but the laminated foam sheets of Example 16 and Comparative Example 15 were difficult to mold, and the laminated foam sheet of Comparative Example 16 was molded. I couldn't.

From this, the foam sheet having a higher density has better moldability, and in the foam sheet, the laminated sheet of the high density foam sheet and the low density foam sheet has better moldability than the single layer sheet. Can be said. From the above, in the polystyrene-based resin foam laminated sheet in which the high density foam sheet and the low density foam sheet are laminated, the high density foam sheet has a density of 0.7 g / cc to 0.13 g / cc and a thickness of 0.
2 mm to 2.8 mm, the average cell diameter is 30 μm or more, and the number of cells in the thickness direction is 3 or more, and the low density foam sheet has a density of 0.22 g / cc to 0.042 g / c.
c, if the thickness is 3.0 mm or less, it is more effective than a single-layer sheet in terms of strength as compared with a single-layer sheet having the same thickness. It has been found that the two-layer sheet has much better moldability if the magnification (density) is the same.

[0080]

[Table 3]

[0081]

EFFECT OF THE INVENTION By using the polystyrene resin foam laminated sheet according to the present invention, the rib compression strength is high even when formed by using the laminated sheet having the same thickness and the same density as the conventional polystyrene resin foam sheet. A molded product having good moldability can be obtained. As a result, it becomes possible to manufacture a molded product made of a polystyrene-based resin foam sheet having a required strength with a material saving and a low cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI B29L 9:00 B65D 1/00 B (56) References JP-A-5-96673 (JP, A) JP-A-6-107842 ( JP, A) JP 58-171370 (JP, A) JP 7-60816 (JP, A) JP 8-119318 (JP, A) JP 9-141773 (JP, A) 63-6005 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 47/00-47/95 B32B 1/00-35/00

Claims (9)

(57) [Claims] 1. A polystyrene resin foam laminated sheet, wherein the foam laminated sheet comprises a high density foam sheet and a low density foam sheet laminated together, and the high density foam sheet has a density.
0.38 g / cc to 0.13 g / cc , thickness 0.2 mm
˜2.8 mm, an average cell diameter of 30 μm or more, and an average of 3 or more cells arranged in the thickness direction, and the low-density foamed sheet has a density of 0.22 g / cc to 0.042 g /
cc, the thickness is 3.0 mm or less, and the total thickness of the high-density foamed sheet and the low-density foamed sheet is 0.7 mm to 3.
A polystyrene-based resin foam laminated sheet having a range of 5 mm. 2. The low-density foamed sheet according to claim 1, wherein
It is 0.2 mm-2.8 mm, The foaming laminated sheet of Claim 1 characterized by the above-mentioned. 3. The foamed laminated sheet according to claim 1, wherein at least one layer of the thermoplastic resin film is laminated on at least one surface of the foamed laminated sheet according to claim 1. 4. The foamed laminated sheet according to claim 1, wherein at least one of the high density foamed sheet and the low density foamed sheet is colored. 5. A molded article using the foamed laminated sheet according to claim 1, wherein the high density foamed sheet is inside the molded article. 6. A molded product using the foamed laminated sheet according to claim 1, wherein the high-density foamed sheet is inside the molded product, and at a boundary portion between a side wall portion and a bottom portion of the molded product. The high density foam sheet has a thickness of 0.2 m
A molded product designed to have a range of m to 3.0 mm. 7. Density 0.38 g obtained by extrusion foaming
/ Cc to 0.13 g / cc, thickness 0.2 mm to 2.8 m
m, an average cell diameter of 30 μm or more, and a polystyrene-based high-density foamed sheet in which an average of 3 or more cells are arranged in the thickness direction, and the density obtained by extrusion foaming is 0.22 g / cc.
A method for producing a polystyrene-based resin foam laminated sheet, comprising laminating with a polystyrene-based low-density foam sheet having a thickness of 0.042 g / cc and a thickness of 3.0 mm or less by an appropriate means. 8. A method for producing a polystyrene-based resin foam laminated sheet, which comprises laminating at least one layer of a thermoplastic resin film on at least one side of the foam laminated sheet according to claim 7. 9. The method for producing a polystyrene resin foam laminated sheet according to claim 7, wherein the polystyrene high density foam sheet and the polystyrene low density foam sheet are laminated by coextrusion.