JP2001310429A - Polypropylene resin foamed sheet laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin formed sheet laminate with excellent lightweight properties and heat resistance and with excellent rigidity and furthermore, with beautiful appearance. SOLUTION: In the polypropylene resin foamed sheet laminate of the present invention, a polypropylene resin layer with a thickness of 20-130 μm prepared by extrusion lamination of a polypropylene resin with a melt flow rate of at least 0.8 g/10 min under a condition of a temperature of 230 deg.C and a load of 21.18 N and a melt tension of a least 0.6 cN at 270 deg.C is formed on one face of the polypropylene resin formed sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin foam sheet laminate.

[0002]

2. Description of the Related Art Conventionally, food packaging containers and the like obtained by thermoforming a polystyrene resin foam sheet have been widely used. These containers are excellent in lightness, appearance, rigidity, and heat insulation, and are suitable as packaging materials. However, with the recent spread of microwave ovens, heat resistance and the like have been further required.

[0003] On the other hand, as a material for a foamed sheet for thermoforming instead of a polystyrene-based resin foamed sheet, a polypropylene-based resin foamed sheet has recently been receiving attention. This foamed sheet is manufactured by extrusion foaming using the resin as a raw material in the wake of the development of a high melt tension type polypropylene resin having long chain branches by Montell Corporation in the United States.

However, the foamed polypropylene resin sheet is superior in heat resistance to the conventional foamed polystyrene resin sheet, but is insufficient in lightness, appearance, rigidity, and heat insulation, so that there is still room for improvement. It was something to leave.

[0005]

SUMMARY OF THE INVENTION The above disadvantages have been solved,
As a means of obtaining a foamed polypropylene resin sheet having high lightness and heat insulation and high rigidity, a method of laminating a non-foamed resin layer on a foamed polypropylene resin sheet having a high expansion ratio by thermal lamination (Japanese Patent Laid-Open No. 6-90)
6) was attempted. However, in this method, there is a limit in the thickness of a film that can be laminated, and sufficient rigidity cannot be obtained. If a film is laminated through an adhesive such as hot melt, a high-thickness film can be laminated, but a decrease in heat resistance cannot be avoided.

A method of laminating a foamed polypropylene resin sheet and a non-foamed resin layer by coextrusion (Japanese Patent Laid-Open No.
166942, JP-A-5-288442) have also been tried. However, in the co-extrusion method, the non-foamed resin layer and the foamed layer are laminated in the die. Therefore, when the thickness of the non-foamed resin layer is increased, the foamed sheet obtained by exposing the foamed layer to the heat of the non-foamed resin layer is obtained. Since the cells become open cells, the inconvenience that the surface of the foam sheet becomes uneven during thermoforming occurs.

[0007]

The present inventors have conducted intensive studies on a method of laminating a foamed polypropylene resin sheet and a non-foamed resin layer by extrusion lamination, and as a result, have found that a specific resin is used for the non-foamed resin layer. Thus, the inventors have found that the above-mentioned problems can be solved, a lightweight, heat-resistant, and excellent rigidity can be obtained, and a polypropylene resin foam sheet laminate having a beautiful appearance can be obtained.

The polypropylene resin foam sheet laminate of the present invention has a melt flow rate of 0.8 g / 10 min or more at a temperature of 230 ° C. and a load of 21.18 N, and a melt tension of 0.6 cN or more at 270 ° C. Extrusion lamination of polypropylene resin of thickness 20 to 1
It is characterized in that a polypropylene resin layer of 30 μm is formed on one side of a foamed polypropylene resin sheet.

Further, another polypropylene resin foam sheet laminate of the present invention has a temperature of 230 ° C. and a load of 21.18 N.
0.8 g / 10 melt flow rate under the conditions of
The polypropylene resin film is formed on one side of a foamed polypropylene resin sheet via a polypropylene resin layer having a thickness of 20 to 130 μm formed by extrusion laminating a polypropylene resin having a melt tension at 270 ° C. of 0.6 cN or more at 270 ° C. or more. Is characterized by being laminated.

[0010] The basis weight of the polypropylene resin foam sheet laminate is preferably 450 g / m ² or less, so that the apparent density of the foam sheet is 0.1 to 0.1.
It is preferably 2 g / cm ³ .

The tensile strength of the polypropylene resin film is preferably 2 MPa or more at 23 ° C., and the tensile elongation in the machine direction and the transverse direction is preferably 300% or more at 23 ° C.

The polypropylene resin foam sheet laminate of the present invention has a structure in which at least one side of the polypropylene resin fill has a printed portion, and a polypropylene resin layer is laminated on the surface of the film having the printed portion. Is preferred.

The polypropylene-based resin film having a printed portion on at least a part of one surface has a surface wetting index of 3
It is preferable that a printed portion is formed on a film surface of 8 dyn / cm or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A foamed polypropylene resin sheet (hereinafter referred to as “foamed sheet laminate”) of the present invention is a foamed polypropylene resin sheet (hereinafter referred to as “foamed sheet”).
It is called "foam sheet". ) And a polypropylene-based resin layer (hereinafter referred to as a “non-foamed resin layer”) laminated on one side of the foamed sheet. The thickness of the non-foamed resin layer is 2
0 to 130 μm, and preferably more than 30 μm, less than 95 μm, and more preferably 35 from the viewpoint of adhesiveness and light weight.
７０70 μm.

If the thickness of the non-foamed resin layer is less than 20 μm, the effect of reinforcing the rigidity of the foamed sheet cannot be expected, and if the thickness of the non-foamed resin layer is too thin,
Adhesive strength with a foamed sheet sufficient to withstand use at high temperatures cannot be obtained. If the thickness of the non-foamed resin layer is small and the adhesive strength is weak, peeling off from the foamed sheet may occur if the food is placed in a container obtained by thermoforming from a foamed sheet laminate and heated in a microwave oven. appear. When the thickness of the non-foamed resin layer exceeds 130 μm, the rigidity is improved, but the lightness of the foamed sheet laminate becomes insufficient.

The non-foamed resin layer of the foamed sheet laminate of the present invention is formed on one side of a foamed sheet by extrusion lamination. According to the extrusion lamination, a non-foamed resin layer having a thickness of 20 to 130 μm can be formed by extruding a resin having a configuration described later into a film shape without damaging the foamed sheet.

The melt flow rate of the polypropylene resin constituting the non-foamed resin layer is 230 ° C. under a load of 2
Must be at least 0.8 g / 10 min under 1.18 N conditions. 0.8 g / 1 of the melt flow rate
If the time is less than 0 minutes, the flow of the resin is poor, so that the non-foamed resin layer cannot be extruded unless the temperature of the extrusion laminate is set high. If the production of a foamed sheet laminate is continued in a state where the resin temperature is too high, black spots due to deterioration of the resin generated in the extruder are mixed into the non-foamed resin layer, and the appearance of the non-foamed resin layer is deteriorated. Cannot be obtained. The upper limit of the melt flow rate is generally about 20 from the viewpoint of workability.
g / 10 minutes. In addition, black dots indicate that the extruded resin temperature is 300
If the temperature exceeds 100 ° C., the temperature may be increased. In order not to generate black spots, the extruded resin temperature is preferably lower than 300 ° C.
90 ° C. or lower is preferable, and particularly 280 ° C. or lower is preferable.

The polypropylene resin constituting the non-foamed resin layer has a melt flow rate of 0.8 g / 10 min or more at a temperature of 230 ° C. and a load of 21.18 N, and a melt tension at 270 ° C. of 0.6 cN or more. (Preferably 0.8 cN or more, more preferably 1.0 cN or more). When the melt flow rate and the melt tension are within these ranges, the required adhesiveness is ensured, and at the same time, the non-foamed resin layer can be formed without generating black spots. When the melt tension is less than 0.6 cN, even if the melt flow rate under the above conditions is 0.8 g / 10 min or more, the viscosity of the resin in the melted state is too small, and the resin having a uniform thickness and a foamed sheet cannot be used. There is a possibility that a non-foamed resin layer having good adhesiveness cannot be formed.
The upper limit of the melt tension is about 30 cN from the viewpoint of processability and moldability of the obtained foamed sheet laminate.

When the adhesiveness between the foamed sheet and the non-foamed resin layer is insufficient, the food is wrapped in a container obtained by thermoforming from the foamed sheet laminate and heated in a microwave oven. At the interface with the layer, large peeling occurs, or small peeling occurs and appears as blisters.

In the present specification, the melt flow rate of the polypropylene resin is measured under the condition 14 in Table 3 of JIS K7210.

In the present specification, the melt tension (melt tension: MT) was measured using a melt tension tester type II manufactured by Toyo Seiki Seisaku-Sho, Ltd. with a nozzle diameter of 2.095.
mm, using a nozzle with a length of 8 mm, resin temperature 270 ° C,
The resin is extruded in a string shape at a piston speed of 10 mm / min, and the string is hung on a tension detecting pulley having a diameter of 45 mm, and then 5 rpm / sec (winding acceleration of the string:
1.3 × 10 ^-2 m / sec ²⁾ about gradually increasing the wound-up speed at a rate of take-wound in winding-up roller with a diameter of 50mm while gradually. In the present invention, the melt tension (M
In order to obtain T), first, the winding speed is increased until the string hanged on the tension detecting pulley is cut, and the winding speed R (rpm) when the string is cut is obtained. Then
The string is wound at a constant winding speed of R × 0.7 (rpm), and the melt tension of the string detected by a detector connected to the pulley for tension detection is measured with time. If the vertical axis indicates the melt tension and the horizontal axis indicates time, a graph having amplitude as shown in FIG. 3 is obtained. As the melt tension in the present invention, the median value (X) of the amplitude of the portion where the amplitude is stable in FIG. 3 is employed. However, if the string does not break even when the winding speed reaches 500 rpm, the winding speed is set to 50.
The melt tension of the string is obtained from a graph obtained by winding the string at 0 rpm. In addition, when measuring the melt tension over time, a unique amplitude value may be rarely detected, but such a unique amplitude value is ignored.

At the beginning of the development of the foamed sheet laminate, the present inventors tried to form a non-foamed resin layer using a general polypropylene resin. However, when a general polypropylene-based resin alone was used, it was not possible to form a non-foamed resin layer without generating black spots at the same time as securing the necessary adhesiveness. As a result of intensively pursuing the cause, the present inventors have been able to elucidate the necessity of using a specific polypropylene resin having a melt flow rate and a melt tension within the above-mentioned ranges simultaneously.

Examples of the polypropylene resin satisfying the above constitution of the present invention include resins selected from propylene homopolymers and copolymers of propylene and other monomer components on the basis of satisfying the above constitution. It is preferable to select from among polypropylene homopolymers having excellent rigidity and heat resistance.

In the case of a copolymer, any of a block copolymer, a random copolymer and a graft copolymer can be used, and not only a binary copolymer but also a ternary copolymer is used. You can also. Among these, as the polypropylene-based resin used for the foamed sheet of the present invention, a block copolymer excellent in heat resistance and impact resistance at a low temperature, particularly a propylene-ethylene block copolymer, is preferable.

In the case of the above block copolymer, it is preferable that other monomer components other than propylene are contained in an amount of 20.0% by weight or less, and in the case of a random copolymer, it is 5.0% by weight or less. Is preferably contained at a ratio of If the amount of other monomer components contained in the copolymer is larger than this, the inherent properties such as rigidity and heat resistance of polypropylene may be impaired. Other monomer components copolymerizable with propylene include ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene,
1-heptene, 3-methyl-1-hexene and the like.

In the non-foamed resin layer of the present invention,
The polypropylene-based resin can be used alone or in combination of two or more. Further, the polypropylene resin of the present invention may contain, within the range of the melt flow rate and the melt tension, a high-density polyethylene, a low-density polyethylene, a linear low-density polyethylene, a linear ultra-low-density polyethylene, and ethylene-butene. Polymers, ethylene resins such as ethylene-maleic anhydride copolymers, butene resins, polyvinyl chloride resins such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer, and styrene resins (preferably 30% by weight). A mixture of the following ranges) can also be used.

Further, the non-foamed resin layer of the present invention may be constituted by mixing a raw material to be described later and a general raw material so that the melt flow rate and the melt tension fall within the above-mentioned ranges. Can be. By adopting such a configuration, an inexpensive foamed sheet laminate can be obtained.

The foam sheet of the present invention contains a polypropylene resin as a main component. Examples of the polypropylene resin include a propylene homopolymer and a copolymer of propylene and another monomer component. In the case of a copolymer, any of a block copolymer, a random copolymer, and a graft copolymer can be used, and not only a binary copolymer but also a ternary copolymer can be used. . Among these, as the polypropylene resin used for the foamed sheet of the present invention, a polypropylene homopolymer having excellent rigidity and heat resistance and a block copolymer having excellent heat resistance and impact resistance at low temperature, especially propylene-ethylene block copolymer, are used. Polymers are preferred.

In the case of the above block copolymer, it is preferable that other monomer components other than propylene are contained in an amount of 20.0% by weight or less, and in the case of a random copolymer, it is 5.0% by weight or less. Is preferably contained at a ratio of If the amount of other monomer components contained in the copolymer is larger than this, the inherent properties such as rigidity and heat resistance of polypropylene may be impaired.

Other monomer components copolymerizable with propylene include ethylene, 1-butene, isobutylene,
-Pentene, 3-methyl-1-butene, 1-hexene,
Examples include 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene and the like. Further, in the foamed sheet of the present invention, the polypropylene-based resin can be used not only alone but also in combination of two or more kinds. Further, the polypropylene resin of the present invention includes a high-density polyethylene, a low-density polyethylene, and a linear low-density polyethylene within a range (preferably not more than 30% by weight) in which the inherent properties of polypropylene as described above are not impaired. Ethylene resins such as linear ultra-low density polyethylene, ethylene-butene copolymer, ethylene-maleic anhydride copolymer, butene resins, polyvinyl chloride, vinyl chloride such as vinyl chloride-vinyl acetate copolymer A system resin, a styrene resin or the like can be mixed.

The foamed sheet of the present invention contains the above-mentioned polypropylene resin as a main component, and preferably has an equilibrium compliance (J ₀ ) in dynamic viscoelasticity measurement at 210 ° C. of 1.
It is obtained by extrusion-foaming a base resin of 2 × 10 ^{−3 to} 20.0 × 10 ⁻³ Pa ⁻¹ , more preferably 2.0 × 10 ^{−3 to} 15.0 × 10 ⁻³ Pa ^−1. .

Equilibrium compliance of base resin (J ₀ )
Is less than 1.2 × 10 ⁻³ Pa ⁻¹ , a foamed sheet may not be obtained. On the other hand, when the equilibrium compliance (J ₀ ) exceeds 20.0 × 10 ³ Pa ⁻¹ , the thermoformability of the obtained foamed sheet may be reduced.

The equilibrium compliance (J ₀ ) is measured by a dynamic viscoelasticity analyzer (Dynamic Analyzer SR manufactured by Rheometrics Scientific F.E.)
200).

The measurement of the equilibrium compliance (J ₀ )
Specifically, it is obtained as follows. First, a disk sample having a diameter of 25 mm is prepared from a measurement resin plate having a thickness of 2 mm obtained by press molding for 5 minutes under the conditions of a temperature of 260 ° C. and a pressure of 8000 kPa using a heat press.
Next, this sample was subjected to a dynamic viscoelasticity measurement with a diameter of 25 mm.
After raising the temperature to 210 ° C. between the parallel plates and leaving it under a nitrogen atmosphere for about 10 minutes, the interval between the parallel plates was adjusted to 1.4 mm, and the molten resin protruding from the parallel plates was removed. Then, a constant stress σ of 100 Pa is applied to the sample melted in a nitrogen atmosphere.
The upper parallel plate is rotated so that c is applied, and the time-dependent change of the strain amount γ (t) is measured based on the time t = 0 when the constant stress σc is applied. The amount of strain γ (t) sharply increases at first, but gradually increases with time, and changes linearly with time after a sufficient time has elapsed.

The dynamic analyzer SR200
The device setting of the mold is as shown in Table 1, and the equilibrium compliance (J ₀ ) is calculated by an automatic function on the device.

[0036]

[Table 1]

The value obtained by dividing the strain γ (t) by the constant stress σc is called creep compliance J (t) and is defined by the following equation (1).

[0038]

J (t) = γ (t) / σc (1)

The creep compliance J (t) suddenly increases at the beginning like the strain amount γ (t), but gradually increases with time, and changes linearly with time after a sufficient time has passed. (Shown in FIG. 1). The creep compliance J that changes linearly
(T) can be represented by the following equation (2).

[0040]

J (t) = J ₀ + t / η (2)

The equilibrium compliance (J ₀ ) in this specification is given as J _{0 in} equation (2). That is, the creep compliance J (t) is plotted on the vertical axis, and the time t
Is plotted on the horizontal axis, and is given as an intercept at time t = 0 when the linear portion of the creep compliance J (t) is extrapolated to time t = 0.

The polypropylene resin used in this specification is used as a main component, and a specific equilibrium compliance (J
_{As the} base resin having ( ₀ ), for example, a polyolefin component such as ultrahigh molecular weight polypropylene or polyethylene is dispersed without ubiquity in a polypropylene resin by a catalyst technique, and a specific equilibrium compliance (J ₀ ) is satisfied. Those which realize entanglement of molecular chains, those obtained by modifying a polypropylene resin with an isoprene monomer or the like so as to satisfy a specific equilibrium compliance (J ₀ ), and the like can be used. Specifically, a polypropylene-based resin “PF-814” or “SD-
632 "can be selected. However, the base resin used in the present invention is preferably one having a polypropylene resin as a main component and having a specific equilibrium compliance (J ₀ ), and is not limited to a synthesis method, a modification method, and an adjustment method of the base resin. .

The cell shape of the foamed sheet of the present invention preferably satisfies the following expressions (3) to (5).

[0044]

## EQU3 ## 0.3 <A / B <0.8 (3)

[0045]

[Expression 4] 0.3 ≦ A / C <0.8 (4)

[0046]

[Expression 5] 0.07 ≦ A <0.18 (5)

However, A in the formulas (3), (4) and (5)
Each of B and C is the average cell diameter in the thickness direction, extrusion direction (MD direction), and width direction (TD direction) of the foamed sheet, and the unit thereof is mm.

A foamed sheet having a cell shape satisfying the formulas (3) to (5) has a small average cell diameter and thus has a beautiful appearance. In addition, since the cell shape is closer to a sphere, the foam sheet is lightweight and rigid. Are better.

The cell shape of the foamed sheet is determined by observing the vertical section in the extrusion direction (MD) of the foamed sheet and the vertical direction (TD) with respect to the MD with a microscope.
D The average cell diameter A in the thickness direction of the vertical cross section, the average cell diameter B of MD, and the average cell diameter C of TD are measured, and the ratio of A to B and C (A / B, A / C) is determined. This measurement is five times the width (T × 5) of the thickness (T) in a microscope enlarged photograph.
All the air bubbles existing in the area are measured.

The foamed sheet of the present invention is obtained by extruding and foaming the base resin. As the extrusion foaming, for example, the base resin is heated and melted in an extruder, kneaded, and further, a foaming agent is injected under a high temperature and a high pressure, and kneaded to form a foamable molten resin composition, which is provided at the extruder tip. Extruded under atmospheric pressure through an annular die to foam into a tubular shape, and cut the tubular foam along the extrusion direction to form a foamed sheet.

As the foaming agent, a physical foaming agent and a chemical foaming agent are used. Among the physical foaming agents, examples of the inorganic foaming agents include carbon dioxide, air, and nitrogen. Among the physical foaming agents, organic compounds include aliphatic hydrocarbons such as propane, n-butane, i-butane, pentane and hexane; cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane; chlorofluoromethane; Trifluoromethane, 1,1
-Difluoroethane, 1-chloro-1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride, methylene chloride, etc. And the like can be used. Further, as the chemical blowing agent, azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile,
Sodium bicarbonate or the like can be used.

These foaming agents can be used by being appropriately mixed. The amount of the foaming agent used varies depending on the type of the foaming agent, the desired expansion ratio of the foamed sheet, and the like. However, the standard of the amount of the foaming agent used to obtain the foamed sheet of the present invention is 100 parts by weight of the base resin. In the case of a physical foaming agent, 0.5 to
It is about 25 parts by weight (butane equivalent).

In the production of the foamed sheet of the present invention, a cell regulator may be added to the base resin as required. Examples of the foam control agent include inorganic powders such as talc and silica, acidic salts of polyvalent carboxylic acids, and reaction mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate. In general, it is preferable that the amount of the bubble adjuster is about 3 parts by weight or less per 100 parts by weight of the base resin.

Further, if necessary, various additives such as an antistatic agent, a fluidity improving agent and the like and a coloring agent in an amount which does not disturb the intended purpose can be added to the base resin. Further, talc, silica, calcium carbonate, clay, zeolite, alumina, barium sulfate and the like can be added as an inorganic filler. The upper limit of the amount of the inorganic filler to be added is preferably 40% by weight of the total weight of the resin and other additives. The inorganic powder and the inorganic filler preferably have an average particle size of 1 to 70 μm. When the inorganic filler is added, the heat resistance and rigidity of the obtained foamed sheet are improved, and the calories burned when the foamed sheet is incinerated can be reduced.

The apparent density of the foamed sheet of the present invention is usually 0.09 to 0.4 g / cm ³ ,
In terms of rigidity, heat insulation and moldability, the apparent density is 0.1 to
It is preferably 0.2 g / cm ³ . If the apparent density is less than 0.09 g / cm ³ , the rigidity of the molded article obtained by thermoforming may be weak, or the corners and irregularities of the molded article may be clearly formed (hereinafter, “mold reproduction”). There is a possibility that the thermoformability may be deteriorated, such as not being able to perform the process. On the other hand, if the apparent density exceeds 0.4 g / cm ³ , there is a possibility that the lightweight, heat insulating, and cushioning properties of the foamed sheet laminate may deteriorate.

The measurement of the apparent density in this specification is based on J
It shall be performed in accordance with IS K6767.

The foamed sheet of the present invention usually has a thickness of 0.1 mm.
5 to 4.0 mm, preferably 0.5 to 2.5 mm, particularly preferably 0.8 to 2.3 mm. When the thickness is less than 0.5 mm, the heat insulating property may be deteriorated. When the thickness is more than 4.0 mm, the molding cycle during thermoforming, the reproducibility of the mold, the lightness and the like may decrease. There is a fear.

The foamed sheet laminate is further laminated with one or more resin layers other than polypropylene resin such as polystyrene resin, polyethylene resin and polyester resin, resin foam layer, nonwoven fabric layer and woven fabric layer. You can also.

A foam sheet laminate according to another embodiment of the present invention comprises:
The melt flow rate under the conditions of a temperature of 230 ° C. and a load of 21.18 N is 0.8 g / 10 min or more, and 270 ° C.
A polypropylene resin film (hereinafter, referred to as a “resin film”) is formed of a foamed sheet through a non-foamed resin layer having a thickness of 20 to 130 μm formed by extrusion laminating a polypropylene resin having a melt tension of 0.6 cN or more. Laminated on one side. The configuration of the non-foamed resin layer and the foamed sheet is the same as the configuration of the foamed sheet laminate. That is,
The foamed sheet laminate of the present invention can be composed of a foamed sheet, a non-foamed resin layer, and a resin film as another embodiment. When the resin film is laminated on one side of the foamed sheet as described above, the surface gloss of the non-foamed resin layer is excellent and the appearance is beautiful. Further, as described later, by laminating the printed resin films, the appearance is further improved.

The resin film of the present invention can be stretched in one direction or in two directions by using a polypropylene resin such as a polypropylene homopolymer or a polypropylene copolymer as a main component (preferably having a polypropylene component of 50% by weight or more). This is the film that was obtained. Further, the resin film may be a multilayer film. As the film, a film having a thickness of preferably 20 to 50 μm, more preferably more than 30 μm and 45 μm or less is used. The foamed sheet laminate in which such a film is laminated has an appearance,
Formability and rigidity are further improved. When a resin film having a tensile strength of 2 MPa or more at 23 ° C. is used, the rigidity of the obtained foamed sheet laminate is further improved.

The tensile elongation in the longitudinal and transverse directions of the resin film is preferably 300% or more at 23 ° C. By using a resin film having a tensile elongation of 300% or more, the thermoformability of the obtained foamed sheet laminate is further improved, and a molded article having a uniform thickness can be obtained. Also, the mechanical properties such as the rigidity of the material are improved.

The tensile strength and the tensile elongation of the resin film were determined in accordance with JIS K 6767, using a dumbbell-shaped No. 1 shape, a distance between chucks of 70 mm and a tensile speed of 500 m.
m / min.

The resin film preferably has a printed portion on at least a part of one side thereof, and a non-foamed resin layer is preferably laminated on the side of the film having the printed portion. Such a foamed sheet laminate in which a resin film with a beautiful appearance is laminated has high design value and therefore has high commercial value.

The resin film having a printed portion on at least a part of one surface preferably has a printed portion formed on a film surface having a surface wetting index of at least 38 dyn / cm, particularly at least 40 dyn / cm. When the surface wetting index is less than 38 dyn / cm, food such as spaghetti, buckwheat, fried rice is packaged in a container obtained by thermoforming the foamed sheet laminate, and the printed portion and the resin are heated when heated in a microwave oven. Peeling occurs between the film and the film, resulting in small blisters, which may impair the appearance.

The surface wetting index was measured at 23 ° C. and 50% humidity.
% Atmosphere, based on JIS K6768,
The measurement is performed at a total of six positions of 1/4, 1/2, and 3/4 in the lateral direction of the two test pieces, and the average value of the measurement results is adopted as the surface wetting index.

The basis weight of the foamed sheet laminate of the present invention can be determined in any of the embodiment composed of the foamed sheet and the non-foamed resin layer and the embodiment composed of the foamed sheet, the non-foamed resin layer and the resin fill. 450 g / m ² or less, with a basis weight of 38
It is preferably 0 g / m ² , particularly preferably having a basis weight of 350 g / m ² . If the basis weight is large, lightness is lost and the cost is high.

The foamed sheet laminate of the present invention comprising a foamed sheet and a non-foamed resin layer and the foamed sheet laminate comprising a foamed sheet, a non-foamed resin layer and a resin film may be produced by a method known per se. Can be. A typical method will be described with reference to FIG. In FIG. 2, 1 is a laminating apparatus, 2 is a foam sheet, 3 and 4 are rolls,
5 is a lami roll, 6 is a gap formed by the roll 4 and the Rami roll 5, 7 is a non-foamed resin layer, 8 is a T die,
9 is a resin film, 10 is a supply roll of a long resin film, 11 is a roll, 12 is a wrinkle removing roll,
Reference numeral 13 denotes a foam sheet laminate.

In order to manufacture a foamed sheet laminate comprising a foamed sheet and a non-foamed resin layer, first, the foamed sheet 2 is introduced into the roll 3 of the laminating apparatus 1, and then the roll 4 is placed along the roll 4. It is introduced into the gap 6 between the ramirole 5 and the ramirole 5, and is then taken off along the ramirole 5. At this time, the non-foamed resin layer 7 extruded in the form of a film from a T-die 8 provided above the gap 6 formed by the roll 4 and the Lami roll 5 flows down onto the foam sheet 2, When the non-foamed resin layer 7 and the foamed sheet 2 are press-bonded with each other, a foamed sheet laminate is obtained.

In the case of producing a foamed sheet laminate comprising a foamed sheet, a non-foamed resin layer and a resin film,
In the same manner as described above, the foamed sheet is introduced into the gap 6 between the roll 4 and the lami-roll 5, and the non-foamed resin layer 7 is
From a T-die into a film,
Is supplied from the resin film supply roll 10 to the gap 6 between the roll 4 and the lami roll 5 through the roll 11 and the wrinkle removing roll 12, and the resin film 7, the non-foamed resin layer 7, and the foam sheet 2 are formed by the roll 4 and the lami roll 5. Is pressed to obtain a foamed sheet laminate 13 of an embodiment composed of a foamed sheet, a non-foamed resin layer, and a resin film.

The laminating apparatus 1 is provided in a production line for the foamed sheet 2, and if it is possible to produce a foamed sheet laminate immediately after producing the foamed sheet 2, the foamed sheet 2 produced and stored on another line may be laminated. To supply a foamed sheet laminate.

The multilayer foamed sheet of the present invention can be formed by vacuum forming, pressure forming, free drawing forming, plug and ridge forming, ridge forming, matched mold forming, straight forming, drape forming, reverse draw, or the like. A desired molded product can be formed by molding, air slip molding, plug assist molding, plug assist reverse draw molding, or a combination thereof.

The molded article thus obtained has a beautiful appearance and is excellent in heat resistance, water resistance, oil resistance, heat insulation, shape retention, rigidity and the like. It is suitable as a food container to be cooked or reheated in a microwave oven as it is.

When a food container is formed from the foamed sheet laminate of the present invention, it is preferable from the viewpoint of heat resistance and the like that the non-foamed resin layer or the resin film is formed on the inner surface side.

[0074]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

The main raw material of the base resin of the foamed sheets used in Examples 1 to 5 and Comparative Examples 1 to 4 was “PF-814” manufactured by Montell Corporation, and “Butane” was used as the blowing agent.

Table 2 shows the average cell diameter of the foam sheets used in Examples 1 to 5 and Comparative Examples 1 to 4.

[0077]

[Table 2]

The non-foamed resin layers in Examples 1, 2, 4, and 5 were made of a recovered material (hereinafter referred to as “recovered material D”)
That. ) And a raw material for resin film recovery (hereinafter referred to as “recovered raw material E”), and by appropriately adjusting the mixing ratio between the recovered raw material D and the recovered raw material E, the desired melt flow rate and melting This was a non-foamed resin layer having tension. In Example 3, YA- manufactured by Chisso Corporation was used.
A non-foamed resin layer was formed using 400Z.

Example 1 Using the laminating apparatus 1 shown in FIG. 2, a foam sheet 2 having a thickness and an apparent density shown in Table 3 was introduced into the laminating apparatus 1 and having a melt flow rate and a melt tension shown in Table 3. The non-foamed resin layer is extruded from the T-die 8 into a film at the extruded resin temperature shown in Table 3, and flows down onto the foamed sheet 2 from above the gap 6 between the roll 4 and the lami-roll 5, and the lami-roll 5 and the roll 4 To produce a foamed sheet laminate comprising a foamed sheet and a non-foamed resin layer.

Comparative Example 1 Melt flow rates shown in Table 3
A foamed sheet laminate comprising a foamed sheet and a non-foamed resin layer was produced in the same manner as in Example 1, except that the non-foamed resin layer was formed using Chisso Corporation's "CF1064" having a melt tension.

Table 3 shows the evaluation of the basis weight (g / m ² ), rigidity, blister and appearance of the foamed sheet laminates obtained in Example 1 and Comparative Example 1.

The rigidity of the molded product was such that the size inside the opening formed from the obtained foamed sheet laminate was 145 mm × 120.
A container having a depth of 27 mm and a depth of 27 mm (the container was made of a non-foamed resin layer or a resin film on the inner surface side of the container) using Tensilon RTM-500 manufactured by A & D Corporation.
The compression speed is 50 so that the 120 mm direction of the inner dimension of the container opening is compressed in a plane perpendicular to the opening surface of the container.
The load at the time of compressing at 0 mm / min and deforming 60% of the original size was measured, and the rigidity of the molded product was determined from the load by the following formula.

[0083]

[Measurement load (N) / basis weight of foamed sheet laminate (g / m ² )] × 1000 = rigidity of molded article (N · m ² / k)
g) From the above results, ：: the rigidity value of the molded product is 60 N · m ² / kg or more ×: the rigidity value of the molded product is less than 60 N · m ² / kg

The swelling was evaluated as follows. For the container having the same specifications as the container used for the evaluation of rigidity, the following microwave test was performed, and the surface of the container was observed. Mix 120g of rice, 2g of soy sauce and 2g of salad oil. In a container and wrapped in a triple wrap with polyethylene film. Heat in a 1600 w microwave for 50 seconds. The contents were removed, the state of the container was observed, and evaluated according to the following criteria. A: No peeling or blistering occurs. ：: blisters having an area of less than 3 mm ² per piece. Δ: blisters having an area of 3 to 5 mm ² per piece. ×: blisters having an area of more than 5 mm ² are generated per piece.

The appearance was evaluated by visually observing the appearance of the molded article.

[0086]

[Table 3]

Examples 2 to 5 Using the laminating apparatus 1 shown in FIG. 2, a foam sheet 2 having a thickness and an apparent density shown in Table 3 was introduced into the laminating apparatus 1, and a melt flow rate and a melt tension shown in Table 3 were obtained. The non-foamed resin layer 7 having the following is extruded from the T-die 8 into a film at the extruded resin temperature shown in Table 3 and flows down onto the foamed sheet 2 from above the gap 6 between the roll 4 and the lami-roll 5. Thickness, tensile strength, tensile elongation, surface wetting index 40 dy
Non-stretched polypropylene film “30AT” having a thickness of 30 μm or a thickness of 40 μm manufactured by Osaka Resin Processing Co.
As a resin film, a non-stretched polypropylene film “40AT” having a thickness of μm was introduced from above the gap 6 so as to be in contact with the non-foamed resin layer 7, pressed between the lami-roll 5 and the roll 4, and formed into a foamed sheet and a non-foamed resin. A foamed sheet laminate comprising a layer and a resin film was manufactured. The resin film was provided with a printing layer using chlorinated polypropylene as a binder on the surface to be bonded to the non-foamed resin layer.

Comparative Example 2 A foamed sheet and a non-foamed sheet were prepared in the same manner as in Example 3 except that a non-foamed resin layer was formed using “HT0011” manufactured by Chisso Corporation having the thickness, melt flow rate and melt tension shown in Table 3. A foamed sheet laminate comprising a foamed resin layer and a resin film was manufactured.

Comparative Example 3 Example 2 was repeated except that a non-foamed resin layer having the thickness shown in Table 3 was used.
A foam sheet laminate comprising a foam sheet, a non-foam resin layer, and a resin film was produced in the same manner as in the above.

Comparative Example 4 A foam sheet laminate comprising a foam sheet and a non-foam resin layer was produced in the same manner as in Example 1 except that a non-foam resin layer having the thickness shown in Table 3 was formed.

In Examples 2 to 5 and Comparative Examples 2 to 4, Table 3 shows evaluations of the obtained foamed sheet laminates in terms of basis weight (g / m ² ), rigidity, blistering, and appearance.

From the comparison between Example 1, Example 3 and Comparative Example 1 in Table 3, the melt tension at 270 ° C. was 0.6 c.
In the case of N or more, blisters do not occur, but the melt tension is less than 0.1.
In the case of 2 cN, it can be seen that blisters occur.

From the comparison between Example 3 and Comparative Example 2 in Table 3, no black spot occurs when the melt flow rate is large, but when the melt flow rate is 0.3 g / 10 minutes, the black spot of the non-foamed resin layer is It can be seen that there are many occurrences.

From the comparison between Example 4 and Comparative Example 3 in Table 3, when the thickness of the non-foamed resin layer is 20 μm or more, the foamed sheet does not peel off from the non-foamed resin layer and the rigidity is excellent. However, when the thickness of the non-foamed resin layer is 18 μm, peeling of the foamed sheet from the non-foamed resin layer occurs, and the rigidity is deteriorated.

From the comparison between Example 1 and Comparative Example 4 in Table 3, it can be seen that when the thickness of the non-foamed resin layer is 170 μm, small holes are formed on the surface of the non-foamed resin layer, resulting in poor appearance. When the thickness of the non-foamed resin layer exceeds 130 μm, the small holes on the surface of the non-foamed resin layer cause the non-foamed resin layer to flow into fine spaces between bubbles on the surface of the foamed sheet, and Is caused by a small depression. This phenomenon can be prevented by setting the thickness of the non-foamed resin layer to 130 μm or less, particularly 95 μm or less.

[0096]

The polypropylene resin foam sheet laminate of the present invention has a melt flow rate of at least 0.8 g / 10 minutes under the conditions of a temperature of 230 ° C. and a load of 21.18 N.
And a melt tension at 270 ° C. of 0.6 cN or more is formed by extrusion laminating a polypropylene resin having a thickness of 20 cN or more.
A polypropylene resin layer having a thickness of 130 μm is formed on one surface of the foamed polypropylene resin sheet. Therefore,
Even when the expansion ratio of the polypropylene resin foam sheet is high and lacks rigidity, the polypropylene resin foam sheet laminate has high rigidity while maintaining excellent lightness.

Further, since a polypropylene resin having a melt flow rate of 0.8 g / 10 min or more under the conditions of a temperature of 230 ° C. and a load of 21.18 N is extrusion-laminated, no black spots are generated in the polypropylene resin layer. In addition, since a polypropylene resin having a melt tension at 270 ° C. of 0.6 cN or more is extrusion-laminated, even if the melt flow rate is 0.8 g / 10 min or more, which is a good flow resin, a polypropylene resin foam sheet and polypropylene The polypropylene resin layer can be easily formed while maintaining good adhesiveness with the resin layer. In addition, the thickness of the resin layer made of polypropylene resin is 20
Since the thickness is about 130 μm, the rigidity can be reinforced at the same time as ensuring the lightness of the polypropylene resin foam sheet laminate.

The other polypropylene resin foam sheet laminate of the present invention has a melt flow rate of 0.8 g / 10 minutes or more under the conditions of a temperature of 230 ° C. and a load of 21.18 N, and a melt tension of 0.2 g at 270 ° C. Thickness 2 formed by extrusion laminating polypropylene resin of 6 cN or more
A polypropylene resin film is laminated on one side of the foamed polypropylene resin sheet via a resin layer of 0 to 130 μm. When this configuration is employed, the surface gloss of the polypropylene-based resin layer becomes excellent and the appearance becomes beautiful. In addition, laminating a printed polypropylene resin film makes the appearance even better.

When the polypropylene resin foam sheet laminate of the present invention adopts a structure in which the basis weight of the polypropylene resin foam sheet laminate is 450 g / m ² or less, it is excellent in lightweight and inexpensive. .

When the polypropylene resin foam sheet laminate of the present invention adopts a structure in which the apparent density of the polypropylene resin foam sheet is 0.1 to 0.2 g / cm ³ , light weight, heat insulation and cushioning properties are obtained. Will be excellent.

The polypropylene resin foam sheet laminate of the present invention has a structure in which the tensile strength of the polypropylene resin film is 2 MPa or more at 23 ° C. and the tensile elongation in the longitudinal and transverse directions is 23 ° C. By adopting a configuration of 300% or more, the rigidity and moldability of the obtained foamed sheet laminate can be improved.

The propylene-based resin foamed sheet laminate of the present invention has a printed portion on at least a part of one side of a polypropylene-based resin film, and a resin layer is laminated on the side of the film having the printed portion. When adopting the configuration,
The appearance is more beautiful and the design is excellent.

The polypropylene-based resin film having a printed portion on at least a part of one surface has a surface wetting index of 3
When a configuration in which a printed portion is formed on a film surface of 8 dyn / cm or more is employed, even when food is packaged in a container obtained by thermoforming from the laminate of the present invention and heated in a microwave oven, In addition, peeling does not occur at the interface between the resin layer made of a polypropylene resin and the printed portion, and blisters do not appear.

[Brief description of the drawings]

FIG. 1 is a graph showing an example of the relationship between creep compliance J (t) and time.

FIG. 2 is a drawing showing an example of an extrusion minating apparatus used for producing a propylene-based resin foam sheet laminate of the present invention.

FIG. 3 shows a melt tension (MT) when a resin is extruded in a string form from a nozzle of a melt tension tester, and the string-shaped resin is wound up by a winding roller at a constant winding speed.
6 is a graph showing a change with time of the graph.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extrusion mining apparatus 2 Foam sheet 7 Non-foam resin layer 9 Resin film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AK07A AK07B AK07C BA02 BA03 BA10B BA10C BA16 DJ01B EH17A GB23 HB31A JA06A JA13B JJ03 JK01 JK02A JK08A JK14A JL03 YY00 YY00A YY00B

Claims (8)

[Claims] 1. Extrusion lamination of a polypropylene resin having a melt flow rate of 0.8 g / 10 min or more at a temperature of 230 ° C. and a load of 21.18 N and a melt tension of 0.6 cN or more at 270 ° C. Thickness 2
A polypropylene-based resin foam sheet laminate, wherein a polypropylene-based resin layer of 0 to 130 µm is formed on one surface of a polypropylene-based resin foam sheet. 2. A polypropylene resin having a melt flow rate of 0.8 g / 10 min or more at a temperature of 230 ° C. and a load of 21.18 N and a melt tension at 270 ° C. of 0.6 cN or more is extrusion-laminated. Thickness 2
A polypropylene-based resin foam sheet laminate, wherein a polypropylene-based resin film is laminated on one side of a polypropylene-based resin foam sheet via a polypropylene-based resin layer of 0 to 130 µm. 3. The polypropylene resin foam sheet laminate according to claim 1, wherein the basis weight of the polypropylene resin foam sheet laminate is 450 g / m ² or less. 4. The laminated polypropylene resin sheet according to claim 1, wherein the apparent density of the foamed polypropylene resin sheet is 0.1 to 0.2 g / cm ^3. body. 5. The polypropylene resin foam sheet laminate according to claim 2, wherein the tensile strength of the polypropylene resin film is 2 MPa or more at 23 ° C. 6. The polypropylene resin foam sheet laminate according to claim 2, wherein the tensile elongation in the machine direction and the transverse direction of the polypropylene resin film is 300% or more at 23 ° C. . 7. The polypropylene resin film has a printed portion on at least a part of one surface thereof, and a polypropylene resin layer is laminated on the surface of the film having the printed portion. 7. The foamed laminate of a polypropylene-based resin foam according to claim 5 or 6. 8. A polypropylene resin film having a printed portion on at least a part of one surface thereof has a surface wetting index of 38.
The polypropylene resin foam sheet laminate according to claim 7, wherein a printed portion is formed on a film surface of dyn / cm or more.