JP2001026079A - Laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate having proper rigidity by using a general-purpose resin raw material, excellent in cushioning properties, lightweight properties, moldability or water resistance, low in production cost and utilizable as an excellent packaging container or material. SOLUTION: A laminate 1 is constituted by integrally laminating a mixed resin foam layer 3 with a density of 0.065 g/cm3 or less based on 30-55 wt.% of (1) a polystyrenic resin, 30-50 wt.% of (2) a polyethylenic resin with a density of 0.89-0.93 g/cm3 and 10-30 wt.% of (3) a polyethylenic resin with a density of 0.94-0.97 g/cm3 [the sum total of (1), (2), (3) is 100 wt.%] on at least the single surface of a polystyrenic resin foam layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like or plate-like laminate formed by laminating and integrating a polystyrene resin foam and a foam mainly composed of a mixed resin of a polystyrene resin and a polyethylene resin. About.

[0002]

2. Description of the Related Art Conventionally, as packaging materials for transferring and storing articles such as machine parts, computer parts, fruits, confectionery, and the like, packaging materials such as slip sheets and partitioning materials. Corrugated board has been widely used. However, packaging containers and packaging materials made of corrugated board have a problem that paper dust is generated and contaminate the packaged articles, and also have poor water resistance and cannot withstand repeated use.

In recent years, synthetic resin foams have been used for packaging containers and packaging materials to improve the low water resistance of cardboard. As synthetic resin foam used as packaging containers and packaging materials, for example,
A non-crosslinked polyolefin-based resin foam having a density of about 0.5 g / cm ³ extruded from a T die is known. However, this foam is inferior in flexibility and processability, and a package obtained from this foam is used. There has been a problem that containers and packaging materials are heavy and products have poor cushioning properties.

As packaging containers and packaging materials, polystyrene resin foam, crosslinked polyolefin resin foam, low-density non-crosslinked polyethylene resin foam, non-crosslinked polypropylene resin foam, and the like are widely used. .
However, those made of polystyrene resin foam are inferior in flexibility and cushioning property, those made of cross-linked polyolefin resin foam have poor rigidity, have a problem of high production cost, and have low density non-crosslinked polyethylene resin. Foams also have poor rigidity and poor thermoformability, and foams made of non-crosslinked polypropylene resin have room for improvement in cushioning and moldability, as well as manufacturing costs. There was also a problem in terms of.

Further, as described in Japanese Utility Model Publication No. 58-48121, it has been proposed to use a laminate of an expanded polystyrene sheet and an expanded polyethylene sheet as a packaging container or the like. However, this laminate still has room for improvement in terms of cushioning properties and thermoformability. Also,
JP-A-10-24540 discloses that a laminate of a non-crosslinked polypropylene-based resin foam and a polyolefin-based resin foam is used as a partitioning material, but this laminate also has thermoformability and manufacturing cost. Etc., leaving room for improvement.

The present invention has been made to solve the above-mentioned problems, and has excellent cushioning, moderate rigidity, light weight, moldability, water resistance, etc., low manufacturing costs, and excellent packaging containers and packaging. It is an object of the present invention to provide a laminate capable of providing a material.

[0007]

That is, the laminate of the present invention comprises:
On at least one side of the polystyrene resin foam layer,
(1) 30 to 55% by weight of a polystyrene resin, (2) 30 to 50% by weight of a polyethylene resin having a density of 0.89 to 0.93 g / cm ³ , (3) 0.94 to 0.97 g /
Density of 0.065 g / cm containing a mixed resin consisting of 10 to 30% by weight of a polyethylene resin of 10 cm ³ (the total of (1), (2) and (3) is 100% by weight).
³ or less mixed resin foam layers are laminated and integrated.

In the present invention, the density is 0.065 g / cm
The mixed resin foam layer of ³ or less preferably has an open cell ratio of 40% or more.

[0009]

FIG. 1 shows an embodiment of a laminate 1 of the present invention, in which a mixed resin foam layer 3 is laminated and integrated on one surface of a polystyrene resin foam layer 2. .

The polystyrene resin as a base resin of the polystyrene resin foam layer 2 is a polymer mainly composed of styrene, a styrene homopolymer, a vinyl monomer copolymerizable with styrene, and styrene. Copolymer, or a copolymer or mixture with a rubber-based polymer mainly composed of polystyrene generally called an impact-resistant polystyrene resin, or a copolymer with a diene-based monomer. . In the present invention, when an impact-resistant polystyrene resin is used as the polystyrene resin constituting the polystyrene resin foam layer 2, the flexibility of the laminate 1 can be improved.
This is preferable because the elasticity can be improved.

Laminated on the polystyrene resin foam layer 2
The integrated base resin of the mixed resin foam layer 3 is:
Polystyrene resin and density 0.89 ~ 0.93g /
cm ^ThreePolyethylene resin (hereinafter referred to as polyethylene
The system resin is also called low density polyethylene. ) And the density
0.94-0.97 g / cm^ThreePolyethylene resin
(Hereinafter, this polyethylene resin is referred to as high-density polyethylene
Also say. )) As a main component.
The density of the resin in this specification is JIS K7112.
Unit of substance at 23 ° C, determined by Method A of
It is the mass per product. Polystyrene in this mixed resin
As the lene-based resin, the polystyrene-based resin foam layer
The same as the polystyrene resin that makes up
In particular, impact-resistant polystyrene resin is
It is preferable because it can improve flexibility and elasticity,
In particular, the polystyrene constituting the polystyrene resin foam layer 2
When the ren-based resin is also high-impact polystyrene,
(1) It is preferable because the effect of improving flexibility and elasticity is further improved.
No.

The low-density polyethylene and the high-density polyethylene used in the mixed resin foam layer 3 are polymers mainly composed of ethylene, not only ethylene homopolymer but also vinyl acetate, methacrylate, acrylate, propylene, α -Copolymers of ethylene with olefins or other vinyl monomers copolymerizable with ethylene are also included.

The mixed resin foam layer 3 is composed of a resin mainly composed of a mixture of the above-mentioned polystyrene resin, low-density polyethylene, and high-density polyethylene. 55
% By weight, preferably more than 40% by weight and 55% by weight or less, the proportion of high-density polyethylene is 10 to 30% by weight, preferably 15 to 25% by weight, and the proportion of low-density polyethylene is 30 to 50% by weight. Preferably 32-48% by weight
(However, the sum of the proportions of the three resins is 100% by weight).

If the proportion of the polystyrene resin in the resin mixture is less than 30% by weight, the shrinkage of the mixed resin foam layer 3 increases, while if it exceeds 55% by weight, the compatibility with the polyethylene resin during melt-kneading becomes poor. If the rigidity of the foam layer 3 is too high, the foam layer 3 becomes brittle and the rebound resilience becomes poor. If the proportion of the high-density polyethylene in the resin mixture is less than 10% by weight, it becomes difficult to reduce the density of the mixed resin foam layer 3, and if it exceeds 30% by weight, shrinkage of the mixed resin foam layer 3 occurs. As it becomes visible, the rebound resilience becomes impaired. Further, when the proportion of the low-density polyethylene in the resin mixture is less than 30% by weight, the resilience of the foam layer 3 is impaired. On the other hand, when the proportion exceeds 50% by weight, the moldability deteriorates, 3 becomes difficult to reduce the density.

The mixed resin foam layer 3 is mainly composed of a mixed resin composed of polystyrene resin, low density polyethylene and high density polyethylene. That is, the polystyrene resin and low-density polyethylene, not limited to those based on a mixture of only high-density polyethylene,
This means that other polymers may be further mixed as long as the intended purpose of the present invention is not impaired. Other polymers that can be further compounded in the resin mixture, such as polypropylene, polyolefins other than the low-density polyethylene and high-density polyethylene, polyesters such as polyethylene terephthalate, polycarbonate, polyamide, rubber, thermoplastic elastomers and the like No. When a mixture of the above polystyrene, low-density polyethylene, and high-density polyethylene is further mixed with another polymer to form a base resin, the ratio of the other polymer in the base resin may be 35% by weight or less. preferable.

In order to obtain a sheet-like or plate-like foam constituting the polystyrene-based resin foam layer 2 or the mixed resin foam layer 3, for example, a resin is melted in an extruder, and a foaming agent is added thereto and kneaded. After extruding from the annular die at the tip of the extruder and foaming it into a cylindrical shape, the cylindrical foam may be cut open in the extrusion direction to form a sheet, or the cylindrical foam may be passed between rolls and A method of crushing with a squeezing pressure and bonding the inner surface of the cylindrical foam to form a plate shape, and the like. Examples of the foaming agent include normal butane, isobutane, a mixture of normal butane and isobutane, normal pentane, isopentane, aliphatic hydrocarbons such as hexane, cyclobutane, cycloaliphatic hydrocarbons such as cyclopentane, and other halogenated hydrocarbons. Examples include hydrogen, carbon dioxide, water, and a thermal decomposition type blowing agent. These foaming agents are used alone or in combination of two or more.

An appropriate amount of the foaming agent is determined according to the density required for the polystyrene resin foam layer 2 and the mixed resin foam layer 3. For example, when a foaming agent containing normal butane as a main component is used, the density is 0.023.
The mixing amount of the blowing agent necessary to obtain the mixed resin foam layer 3 of about 0.065 g / cm ³ is about 5 to 12 parts by weight based on 100 parts by weight of the resin mixture.

In producing a foam constituting the polystyrene resin foam layer 2 or the mixed resin foam layer 3, a cell nucleating agent is generally used. As the cell nucleating agent, for example, in addition to an inorganic substance such as talc, a chemical foaming agent that decomposes at the temperature in the extruder to generate gas can be used as the cell nucleating agent. An acid-alkali combination that reacts at the temperature in the extruder to generate carbon dioxide gas,
For example, a combination of citric acid and sodium bicarbonate or a combination of an alkali salt of citric acid and sodium bicarbonate can also be used as the bubble nucleating agent. By adding these cell nucleating agents, the size of the cells in the obtained foamed layer can be arbitrarily adjusted, and the flexibility and feel of the foamed layer can be improved.

Further, in order to prevent the permeation of the foaming agent from the resin during foaming and to suppress the shrinkage of the resulting foamed layer, a shrinkage inhibitor is added to the resin (particularly in the mixed resin constituting the mixed resin foam layer). Is preferably added. As such, for example, polyoxyethylene monomyristate, polyoxypropylene monomyristate, polyoxyethylene monopalmitate, polyoxypropylene monopalmitate, polyoxyethylene monostearate, polyoxypropylene monostearate , Polyoxyethylene distearate, monolauric acid glyceride, monominostinic acid glyceride, monopalmitic acid glyceride, monostearic acid glyceride, monoarachiic acid glyceride, dilauric acid glyceride, dipalmitic acid glyceride, distearic acid glyceride, 1-palmito-2-stearin Acid glyceride, 1-
Examples include various aliphatic esters such as stearo-2-myristate glyceride, tristearate glyceride, and monobehenate glyceride. In addition, foam layer 2,
An inorganic filler, a colorant, a fungicide,
Antibacterial agents and rust preventives can also be added.

In the laminate 1 of the present invention, the mixed resin foam layer 3 has a density of 0.065 g / cm ³ or less.
The density of the foam layer having an open cell ratio of less than 40% having better rebound resilience is preferably 0.011 to 0.025 g / cm ³ , particularly preferably 0.013 to 0.025 g / cm ^3.
0.025 g / cm ³ . Thereby, the softness is achieved by lowering the density, and by setting the open cell ratio to less than 40%, excellent rebound resilience is obtained. The density of the foam layer having an open cell ratio of 40% or more having a softer buffering property is 0.025 g / c.
m ³ or less, and particularly preferably 0.03 or less.
It is ³ to 0.06 g / cm ³ . This allows the resilience to be maintained to some extent by increasing the density,
By setting the open cell ratio to 40% or more, the balance with the extremely excellent softness obtained is good. If the density of the mixed resin foam layer 3 exceeds 0.065 g / cm ³ , the lamination 1 will have insufficient buffering properties and thermoformability. The polystyrene resin foam layer 2 has a density of 0.5 to
0.03 g / cm ^3, to be more 0.3~0.05g / cm ^3, rigid, preferred in view of moldability. Laminate 1
Has a thickness of 25 mm in terms of cushioning, moldability, rigidity, etc.
Hereinafter, preferably 2 to 10 mm, more preferably 2 mm
As described above, the thickness of the polystyrene resin foam layer 2 and the mixed resin foam layer 3 is less than 6 mm. Is 0.5 to 8 mm, the thickness of the mixed resin foam layer is 1 to 12 mm, and the thickness ratio between the polystyrene resin foam layer and the mixed resin foam layer is 1: 0.3 to 1: 5. Is preferred.

The laminate 1 of the present invention comprises
Each sheet constituting the resin foam layer 2 and the mixed resin foam layer 3
And foams are manufactured separately by the above method.
Even if both are laminated and integrated by a method such as adhesive, heat fusion, etc.
Good, but polystyrene by co-extrusion applying the above method
Laminated resin foam layer 3 integrated with resin-based resin foam layer 2
You may do it. In addition, both are laminated by co-extrusion method.
The method of integration shows good adhesion without adhesive
Preferred. In the laminate 1 of the present invention, as described above,
The density of the mixed resin foam layer 3 is 0.065 g / cm.^ThreeLess than
It is necessary to be polystyrene resin foam
The body layer 2 has a density of 0.5 to 0.03 g / cm. ^ThreeBeing
Is preferred, but the polystyrene resin foam layer 2 and the mixed resin
Extremely different density due to difference in foaming behavior of foam layer 3
Polystyrene resin foam layer 2 and mixed resin foam layer 3
Is difficult to laminate and integrate by coextrusion. this
Therefore, the polystyrene resin foam layer 2 is formed by a co-extrusion method.
To obtain a laminated body 1 in which a mixed resin foam layer 3 is integrally laminated.
In the case, the density of the polystyrene resin foam layer 2 is mixed.
The density of the composite resin foam layer 3 is 0.2 to 0.7 times,
It is preferable that the ratio be 35 to 0.7 times.

The laminate 1 of the present invention comprises a mixed resin foam layer 3
As the base resin of the polystyrene resin, low-density polyethylene, and high-density polyethylene, by using a resin having a mixed resin as a main component mixed in the above specific ratio, buffering property, moderate rigidity, In addition to having lightness, moldability, water resistance, and the like, since the mixed resin foam layer 3 is laminated and integrated with the polystyrene resin foam layer 2, moldability and rigidity are further improved. You.

In the laminate 1 of the present invention, when a softer cushioning property is required for the purpose of, for example, protecting the surface of an object to be packaged, the mixed resin foam layer 3 has an open cell ratio of 40% or more. Is preferred. In addition, the above-mentioned open cell ratio is AST
MD 2856 This value is obtained by procedure C. When the open cell ratio of the mixed resin foam layer 3 is 40% or more, a soft texture is added to the surface of the mixed resin layer 3 and the surface protection properties of fruits and vegetables such as peaches, pears, tomatoes and precision machine parts. Benefits for the packaging of highly demanding goods,
When the lamination and integration of the mixed resin foam layer 3 and the polystyrene-based resin foam layer 2 are performed by a co-extrusion method, there is an advantage that the densities of both foam layers are consequently closer to facilitate lamination. is there. In order to make the open cell ratio of the mixed resin foam layer 3 40% or more, the balance between the melt tension of the mixed resin and the foaming force of the blowing agent may be adjusted. Specifically, the foaming temperature,
What is necessary is just to adjust with the amount of additives, such as talc, and the amount of a foaming agent. The method of setting the amount of a foaming agent to 5.5 to 10.5% by weight is the easiest and the density of the resin foam layer can be set high. As described above, it is preferable because a certain level of resilience can be secured.

The laminate 1 of the present invention may have a configuration in which a mixed resin foam layer 3 is laminated and integrated on both sides of a polystyrene resin foam layer 2 as shown in FIG.
In the case of the laminate 1 shown in FIG. 2, the mixed resin foam layer 3 may have the same composition or a different density or thickness of the mixed resin, or may have different foam layers. Further, as shown in FIGS. 1 and 2, the laminate 1 of the present invention is not limited to the case where each of the polystyrene foam layer 2 and the mixed resin foam layer 3 has a single-layer structure, but may be a polystyrene resin foam layer. 2. One or both of the mixed resin foam layers 3 may have a laminated structure of two or more layers. The laminate 1 shown in FIG. 3 has a configuration in which a polystyrene resin foam layer 2 is formed by laminating and integrating two polystyrene resin foam layers 2a and 2b.
A laminate 1 in which a mixed resin foam layer 3 is laminated and integrated on both surfaces of a polystyrene resin foam layer having a layer structure is shown.
Further, the polystyrene resin foam layer 2 may be formed by laminating and integrating three or more polystyrene resin foam layers.
FIGS. 1 to 3 show a case where the mixed resin foam layer 3 laminated on one or both sides of the polystyrene resin foam layer 2 has a single-layer structure. The mixed resin foam layer 3 laminated on one side or both sides of the layer 2 may have a laminated structure of two or more mixed resin foam layers. In the case of the laminate 1 in which the mixed resin foam layer 3 is laminated on both sides of the polystyrene resin foam layer 2 as shown in FIGS. 2 and 3, the layer configuration of each mixed resin foam layer 3 is the same. However, for example, the mixed resin foam layer 3 laminated on one surface of the polystyrene resin foam layer has a single-layer structure, and the mixed resin foam layer laminated on the other surface has two or more layers. And may be different from each other. Incidentally, the laminate of the present invention is such that the mixed resin foam layer is directly laminated and integrated on at least one side of the polystyrene resin foam layer without the interposition of a thermoplastic resin layer or an adhesive layer, thereby improving productivity and recycling. It is preferable in terms of properties.

The laminate 1 of the present invention may be one in which a thermoplastic resin layer is further laminated and integrated. FIG. 4A shows a thermoplastic resin layer 4 on one side of a polystyrene resin foam layer 2.
FIG. 4 (b) shows a laminated sheet 1 having a configuration in which the mixed resin foam layer 3 is laminated and integrated through the laminated resin foam layer 3 shown in FIG. Further, a laminate 1 in which a thermoplastic resin layer 4 is laminated and integrated is shown. FIG. 4C shows a laminate 1 in which a thermoplastic resin layer 4 is further laminated on each surface of each mixed resin foam layer 3 in the laminate 1 having the layer configuration shown in FIG. .

Examples of the thermoplastic resin in the thermoplastic resin layer 4 include polyethylene resins such as the above-described high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, polystyrene, and impact-resistant resin. Polystyrene-based resins such as polystyrene, polypropylene-based resins, polyester-based resins, and the like. These sheets are laminated in the form of a sheet or film of these thermoplastic resins or a non-woven fabric made of thermoplastic resin fibers. Among the above thermoplastic resins, a polyethylene resin or a polystyrene resin which does not particularly require an adhesive layer is preferable. By further laminating the thermoplastic resin layer 4 on the laminate 1 composed of the polystyrene resin foam layer 2 and the mixed resin foam layer 3, the thermoformability and rigidity of the laminate 1 can be further improved. In addition, by laminating functional films, functions such as gas barrier properties can be added. In addition, from the viewpoint of improving the thermoformability and rigidity of the laminate 1, the thermoplastic resin layer 4
Are preferably laminated and integrated on both sides of the laminate 1. Further, as shown in FIG. 4A, when the thermoplastic resin layer 4 is provided between the polystyrene resin foam layer 2 and the mixed resin foam layer 3, a decrease in the cushioning performance of the foam layer is hindered. There is no fear. The thermoplastic resin layer 4 is not limited to a single layer but may be a multilayer.

The thickness of the thermoplastic resin layer 4 is usually from 10 to
The thickness is preferably about 500 μm. However,
When the thermoplastic resin layer 4 is provided on the outermost surface, the buffering property on the lamination surface side of the thermoplastic resin layer 4 is reduced as compared with the surface where the thermoplastic resin layer is not laminated, and the resin layer 4 is provided. This itself leads to a decrease in the lightness of the laminate 1. Therefore, it is preferable to reduce the thickness of the thermoplastic resin layer 4 in consideration of the buffering property and lightness of the laminate 1, and in consideration of the balance of thermoformability, rigidity, cushioning property, and lightness of the laminate 1, The thickness of the thermoplastic resin layer 4 is 10 to 60 μm
Is appropriate.

The laminated body 1 in which the thermoplastic resin layers are laminated and integrated is separated into a foam constituting the polystyrene resin foam layer 2 or the mixed resin foam layer 3 and a sheet or film constituting the thermoplastic resin layer separately. After manufacturing in a separate process, a method of laminating and integrating each foam with a thermoplastic resin sheet or film in a separate process, an extrusion lamination method of extruding and laminating a thermoplastic resin from another extruder to an extruded foam, and the like. Among them, a particularly preferable method is a method of laminating and integrating with the polystyrene resin foam layer 2 and the mixed resin foam layer 3 by a co-extrusion method.

The laminate 1 of the present invention is used as various packaging containers and materials for packaging by thermoforming by a method such as vacuum forming and / or pressure forming. For example, to mold a container, the laminate 1 is heated and softened by a heater or the like, and the laminated body 1 heated and softened by a mold having a predetermined container shape is sandwiched, and the laminate 1 is adhered to the surface of the container-shaped mold. By doing so, a container conforming to the shape of the mold is obtained. Also, by adjusting the shapes of the male mold and the female mold used for molding, the gap at the time of mold matching, the molding speed, etc., various characteristics such as the average sheet thickness in each part of the container can be adjusted to a good range. Can be.

In particular, when the laminated body 1 having the structure in which the thermoplastic resin layer 4 is laminated and integrated is used for thermoforming, it is possible to easily obtain a molded body having a complicated rib shape or a deep drawn body. The resulting molded article is more excellent in rigidity and appearance. Thus, the molded body obtained by thermoforming the laminate of the present invention is used, for example, as a container for packaging home appliances, a container for packaging mechanical parts, a container for confectionery packaging, and the like.
In particular, it can be suitably used as a container for packaging fruit and vegetables such as tomato and pear. In addition, the laminate of the present invention is not only thermoformed, but is also cut and processed by, for example, a punching blade, and is suitably used as a packaging material for building materials such as fruits, machine parts, and sashes as a partition material, interleaf paper, and the like. it can.

[0031]

The present invention will be described below in further detail with reference to examples and comparative examples.

Examples 1-4 Nipolon Hard 6300 manufactured by Tosoh Corporation (density 0.9)
6 g / cm ³ high density polyethylene (HDPE)), NS-1 manufactured by Nippon Unicar Co., Ltd. (density 0.92 g / cm 3
Using ³ low density polyethylene (LDPE)) and TA & M Styrene Co., Ltd. Styron 679 (polystyrene of a density 1.05 g / cm ³ (PS) a) in the proportions shown in Table 1, these resins In the mixture, glyceryl monostearate as an anti-shrinkage agent and talc as a cell nucleating agent were blended by adjusting so as to contain 1% by weight, respectively.
A mixed foaming agent of 30% by weight of isobutane and 70% by weight of normal butane was pressed into an extruder and melt-kneaded to obtain a foamed mixed resin melt. In addition, using another extruder, Stylon 679 manufactured by A & M Styrene Co., Ltd. was used as a polystyrene resin, and 1% by weight of talc was added to the styrene-based resin as a cell nucleating agent. Further, the mixed foaming agent of isobutane and normal butane was press-fitted in the amounts shown in Table 1 and melt-kneaded to obtain a foamed polystyrene resin melt.

Next, the two melts were combined and laminated inside a circular die, and co-extruded from the die to obtain a cylindrical foam having a polystyrene resin foam layer positioned on the inner surface. A balloon is formed while cooling the inner and outer surfaces of the extruded cylindrical foam with air, and the balloon is taken out while passing over the surface of the columnar cooling device. The following laminated foam sheet was obtained.

[0034]

[Table 1]

[0035]

[Table 2]

The density, thickness, open cell ratio, etc. of the mixed resin foam layer and the polystyrene resin foam layer shown in Table 2 are as follows:
It is a value obtained by measurement as follows.

Thickness of each foam layer Laminated foam sheet (Laminated foam board in Examples 5 and 6)
In the thickness direction vertical cross section, 20 or more measurement points were selected at equal intervals, and the thicknesses of the mixed resin foam layer and the polystyrene resin foam layer were measured (for Example 7, the thickness of the resin layer was also measured). Each thickness was obtained as an arithmetic average value.

Density of each foam layer Laminated foam sheet (Laminated foam board in Examples 5 and 6)
Of each foam layer, and a measurement sample of 10 cm long × 10 cm wide (thickness of each foam layer) is cut out. The weight (g) of the measurement sample was measured, and the weight (g) was obtained by dividing the weight (g) by the volume (cm ³ ) of the measurement sample obtained from the external dimensions of the measurement sample.

Open cell ratio of each foam layer Laminated foam sheet (Laminated foam plate in Examples 5 and 6)
From each foam layer, and for each foam layer ASTM
D2856 Determined by Procedure C.

The cushioning properties of the laminated foamed sheet obtained in the above example, and a tomato container having a length of 430 mm, a width of 300 mm, and a height of 30 mm were vacuum-formed from the laminated foamed sheet, and the moldability and the obtained molding were obtained. The rigidity of the product was evaluated. Table 3 shows the results. The cushioning property, moldability and rigidity of the laminated foam sheet shown in Table 3 were evaluated as follows.

With respect to Examples 1-4, 7 and Comparative Examples 1, 2, and 4, the tomatoes were stored in the above-mentioned tomato containers, and a transportation test was performed to confirm damage to the tomatoes and misalignment of the storage form. And evaluated according to the following criteria. ○ ・ ・ There is no damage or change in storage form. △: There is no damage, but there are some that rotate slightly and cause misalignment. × ・ ・ There is something damaged. Further, in Examples 5 and 6, a test piece having a length of 50 mm, a width of 50 mm, and a thickness of a laminated body was used in accordance with JIS K7208. The compression test was performed at a test speed of, and the compression elastic modulus was determined from the gradient of the first linear portion of the compression stress-strain curve, and evaluated according to the following criteria.・ · The compression modulus is less than ² kgf / cm ² . Δ: The compression modulus is ² to 5 kgf / cm ² . ×: The compression modulus is more than 5 kgf / cm ² .

Moldability The molded product was visually evaluated according to the following criteria. ：: Good mold reproducibility and uniform thickness of fruit vegetable storage recess. Δ: The mold reproducibility was somewhat poor, but the appearance was good and the thickness of the fruit vegetable storage recess was uniform. ×: Cracks have occurred in a part of the molded product.

Rigid molded product (Laminated foam board in Examples 5 and 6) is fixed at one end in the longitudinal direction and a cantilever test is performed to measure the amount of sag at the other end in the longitudinal direction. And evaluated according to the following criteria. ：: The amount of sag is less than 2 mm. ：: The amount of sag is 2 to 5 mm. ×: The amount of sag is more than 5 mm.

[0044]

[Table 3]

Example 5 The two polystyrene foam sheets obtained in Example 4 were bonded together by heating the sides of the polystyrene resin foam layers with hot air to obtain a mixed resin foam layer / polystyrene resin foam layer / polystyrene. A laminated foam plate laminated in the order of resin foam layer / mixed resin foam layer was obtained. A mixed resin foam layer of this laminated foam board,
Table 2 shows the density, thickness, and open cell ratio of the polystyrene resin foam layer. Incidentally, the thickness of the mixed resin foam layer shown in Table 2,
The density and open cell ratio are values measured for each mixed resin foam layer located on the surface side of the laminated foam board (both mixed resin foam layers had the same thickness, density and open cell ratio). ), The thickness, density, and open cell rate of the polystyrene resin foam layer are the total thickness, the entire density, and the total open cell rate of the two bonded polystyrene resin foam layers.

The cushioning property and rigidity of the laminated foam board were evaluated as described above. The results are shown in Table 3.

Comparative Examples 1-3 Nipolon Hard 6300 (Density 0.9) manufactured by Tosoh Corporation
6 g / cm ³ high density polyethylene (HDPE)), NS-1 manufactured by Nippon Unicar Co., Ltd. (density 0.92 g / cm 3
³ of low density polyethylene (LDPE)) and TA & M Styrene Co., Ltd. Styron 679 (polystyrene of a density 1.05 g / cm ³ (PS) a) with used in a proportion shown in Table 1, these The resin mixture was adjusted to contain 1% by weight of glyceryl monostearate as an anti-shrinkage agent and 1% by weight of talc as a cell nucleating agent, and further blended with these compounds and Example 1 in the amounts shown in Table 1. After melt-kneading with the same foaming agent as described above, the mixture was extruded and foamed into a cylindrical shape from a circular die. A balloon is formed while cooling the inner and outer surfaces of the extruded cylindrical foam with air, and the balloon is taken out while passing through the surface of the columnar cooling device. Thereafter, the balloon is cut open along the extrusion direction and shown in Table 2. A foam sheet was obtained. In Comparative Example 3, a good foamed sheet could not be obtained.

Examples 1 to 4 using the obtained foamed sheets
The same molding as described above was performed, and the cushioning property, moldability and rigidity of the obtained molded body were evaluated in the same manner. The results are shown in Table 3.

Comparative Example 4 An extruder manufactured by Montell Canada Inc .: PF-814
(Polypropylene homopolymer) adjusted to contain 1.2% by weight of talc as a cell nucleating agent, and blended.
Further, the same foaming agent as in Comparative Example 1 was press-fitted in the amount shown in Table 1, melt-kneaded, and extruded into a cylindrical shape from a circular die at a foaming temperature shown in Table 1. A balloon is formed while cooling the inner and outer surfaces of the extruded cylindrical foam with air, and the balloon is taken out while passing over the surface of the columnar cooling device. Thereafter, the balloon is cut open along the extrusion direction and shown in Table 2. The following foamed sheet was obtained.

Examples 1 to 4 using the obtained foamed sheets
The same molding as described above was performed, and the cushioning property, moldability and rigidity of the obtained molded body were evaluated in the same manner. The results are shown in Table 3.

Example 6 A cylindrical foam was obtained in the same manner as in Example 1 except that the amount of the mixed foaming agent added to the mixed resin and the foaming temperature of the foamable resin melt were set to the values shown in Table 1. The extruded cylindrical foam is passed between upper and lower pressing rolls installed on the downstream side to thereby oppose the upper half and the lower half of the polystyrene resin foam layer located on the inner surface of the cylindrical foam. Was heat-bonded to form a plate-like laminate, and then cut in the width direction orthogonal to the extrusion direction to obtain a laminated foam plate shown in Table 2.

Table 2 shows the density, thickness and open cell ratio of the mixed resin foam layer and the polystyrene resin foam layer of the laminated foam board.
Shown in The thickness, density, and open cell ratio of the mixed resin foam layer shown in Table 2 are values measured for each mixed resin foam layer located on the surface side of the laminated foamed board (both mixed resin foam layers). Were the same thickness, density, and open cell rate.), The thickness, density, and open cell rate of the polystyrene resin foam layer were the total thickness, the overall density, of the two bonded polystyrene resin foam layers. It is the total open cell rate.

Example 5 The cushioning property and rigidity of the laminated foam board were measured in Example 5.
The results evaluated in the same manner as in Table 3 are also shown in Table 3.

Example 7 Nipolon Hard 6300 manufactured by Tosoh Corporation (density 0.9
6 g / cm ³ high density polyethylene (HDPE)), NS-1 manufactured by Nippon Unicar Co., Ltd. (density 0.92 g / cm 3
Using ³ low density polyethylene (LDPE)) and TA & M Styrene Co., Ltd. Styron 679 (polystyrene of a density 1.05 g / cm ³ (PS) a) in the proportions shown in Table 1, these resins In the mixture, glyceryl monostearate as an anti-shrinkage agent and talc as a cell nucleating agent were blended by adjusting so as to contain 1% by weight, respectively.
A mixed foaming agent of 30% by weight of isobutane and 70% by weight of normal butane was pressed into an extruder and melt-kneaded to obtain a foamed mixed resin melt. In addition, using another extruder, Stylon 679 manufactured by A & M Styrene Co., Ltd. was used as a polystyrene resin, and 1% by weight of talc was added to the styrene-based resin as a cell nucleating agent. Further, the mixed foaming agent of isobutane and normal butane was press-fitted in the amounts shown in Table 1 and melt-kneaded to obtain a foamed polystyrene resin melt. Further, using another extruder, H640N manufactured by Nippon Polystyrene Co., Ltd. was used as the impact-resistant polystyrene resin, and the mixture was melt-kneaded to obtain a non-foamable resin melt.

Next, the above three kinds of melt-kneaded materials were combined and laminated inside a circular die (the temperature of the non-foamable resin melt was 175 ° C.), co-extruded from the die, and sequentially from the inner surface side. A cylindrical foam was obtained by laminating and integrating a polystyrene resin foam layer, a mixed resin foam layer, and a non-foamed impact-resistant polystyrene resin layer. A balloon is formed on the inner surface and the outer surface of the extruded cylindrical foam while cooling it with air, and the balloon is taken out while passing through the surface of the columnar cooling device, and then cut open along the extrusion direction and shown in Table 2. A laminated foam sheet was obtained. The thickness of the non-foamed impact resistant resin layer was 70 μm.

Examples 1 to 4 using the obtained foamed sheets
The same molding as described above was performed, and the cushioning property, moldability and rigidity of the obtained molded body were evaluated in the same manner. The results are shown in Table 3.

[0057]

As described above, the laminate of the present invention is
An excellent laminate that has cushioning properties, moderate rigidity, light weight, moldability, water resistance, etc., and uses general-purpose resin as a raw material, so it can be supplied to the market at a low manufacturing cost and at low cost. It is. In particular, when the open cell ratio of the mixed resin foam layer is 40% or more, there is an advantage that a soft texture is added to the surface and an appropriate water retention can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of the laminate of the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the laminate of the present invention.

FIG. 3 is a longitudinal sectional view showing still another embodiment of the laminate of the present invention.

FIG. 4 is a longitudinal sectional view showing an embodiment in which a thermoplastic resin layer is further laminated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated body 2 Polystyrene resin foam layer 3 Mixed resin foam layer

Continued on the front page (72) Inventor Satoshi Iwasaki 3271-19 Tsuruta-cho, Utsunomiya-city, Tochigi Prefecture 2-101, Corpora Tsuruta (72) Inventor Yoshiaki Momose 3282-5, Tsuruta-cho, Utsunomiya-shi, Tochigi F-term (reference) 4F100 AK04B AK05 AK12A AK12B AL05B BA02 DJ01A DJ01B DJ03B GB16 JA13B JB07 JK01 JK11 JL01 JL02 JL03 YY00B 4J002 BB02X BB03X BC02W BC03W GF00

Claims (2)

[Claims] At least a polystyrene resin foam layer
Also on one side, (1) 30-55 weight of polystyrene resin
%, (2) density 0.89 to 0.93 g / cm ^ThreePolyet
30 to 50% by weight of styrene resin, (3) density of 0.94 to
0.97 g / cm^Three10-30 layers of polyethylene resin
% Of the mixed resin (provided that (1), (2) and
(3) 100% by weight).
065g / cm^ThreeThe following mixed resin foam layers are laminated and integrated
A laminate characterized in that: 2. The laminate according to claim 1, wherein the open cell ratio of the mixed resin foam layer having a density of 0.065 g / cm ³ or less is 40% or more.