JP2000037805A - Foamed laminated sheet and molded container using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a closed-cell foamed laminated sheet excellent in low temp. impact resistance, heat resistance and deep drawing properties at a time of thermoforming and high in foaming magnification and a molded container using the same. SOLUTION: A foamed laminated sheet is obtained by laminating a polycarbonate resin foamed layer and a polyester resin foamed layer and both foamed layers satisfy formula: 1.4<(Ta/Tb)<34 and formula: 0.7<=(Ta+Tb)<=7, wherein Ta is the thickness (mm) of the polycarbonate resin foamed layer and Tb is the thickness (mm) of the polyester resin foamed layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed laminated sheet suitable for a frozen food container or the like which requires properties such as heat resistance, low-temperature impact resistance, and deep drawability during heat molding, and molding using the same. It concerns a container.

[0002]

2. Description of the Related Art As a packaging material for frozen foods, it withstands a low temperature of -30.degree. C. or less during rapid freezing, does not pass through gas or odor such as water vapor or oxygen, and has a high quality food product. It is necessary to be able to hold In addition, cooked foods, which are the mainstream of frozen foods, are often reheated in a microwave oven and provided directly to a dining table, so that the packaging material also needs to have heat resistance that can be heated in a microwave oven.

[0003] Polycarbonate resin foam is excellent in heat resistance, aging resistance, water resistance, electrical and mechanical properties, and is expected to be applied to industrial materials, building materials, packaging materials, various containers and the like. Have been. Further, the polycarbonate resin foam is particularly suitable as a container for a microwave oven or a retort food container requiring heat resistance, and also a frozen food container requiring low-temperature impact resistance.

[0004] In recent years, a foam sheet extruded and foamed using a polycarbonate resin (Japanese Patent Application Laid-Open No. 8-66953) has been proposed, but the molded article has sufficient low-temperature impact resistance, Has a glass transition temperature of around 150 ° C., so that the shape retention of the molded article rapidly decreases from around 140 ° C. For this reason, when a container containing an oily substance in the contents is heated in a microwave oven, the temperature may exceed 140 ° C., and thus higher heat resistance is required.

As a method for improving such heat resistance, it is conceivable to control the crystallinity of a foam made of a polycarbonate resin and a polyester resin. Therefore, there is a problem that the secondary thickness of the molded body is small and elongation is poor. As a result, the resin concentrates on the bottom surface of the container, and the thickness of the side surface of the container and the lip portion cannot be obtained. In particular, this tendency becomes remarkable when forming a deep drawn container.

On the other hand, a foamed sheet of a polyester resin has excellent mechanical strength, heat resistance, oil resistance, gas barrier properties, and heat moldability (especially molding of a deep drawn container). It is actually used as a container. However, generally used polyester resin foams do not satisfy the low-temperature impact resistance as a frozen food container.

The present invention has been made in view of the above-mentioned prior art, and provides a closed-cell foamed laminated sheet having excellent low-temperature impact resistance, heat resistance, and deep drawability during heat molding, and having a high expansion ratio. An object is to provide a molded container using the same.

[0008]

Means for Solving the Problems The present inventors have studied the low-temperature impact resistance of a foam at -30 ° C or lower, the heat resistance at 140 ° C or higher, and the deep drawability during heat molding. Both of the above disadvantages are compensated for by laminating a polycarbonate resin foam layer with excellent low-temperature impact resistance and a polyester resin foam layer with low-temperature impact resistance but poor deep-drawing moldability and heat resistance. Further, it has been found that the above object can be achieved in combination with the synergistic effect of lamination, and the present invention has been completed.

The present invention has a structure in which a foamed layer of a polycarbonate resin (hereinafter, referred to as a PC layer) and a foamed layer of a polyester resin (hereinafter, referred to as a PAT layer) are laminated. It provides a foam laminated sheet characterized by satisfying the following. 1.4 <(Ta / Tb) <34 0.7 ≦ (Ta + Tb) ≦ 7 [wherein Ta represents the thickness (mm) of the PC layer and Tb
Represents the thickness (mm) of the PAT layer.] Further, the present invention provides a molded container obtained by molding the foamed laminated sheet into a container shape such that the PAT layer is on the inside.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The foamed laminated sheet of the present invention comprises a PC layer and a PA
It has a structure in which T layers are stacked.

The polycarbonate resin in the PC layer is preferably a polycarbonate obtained from carbonic acid and glycol or bisphenol. An aromatic polycarbonate having diphenylalkane in the molecular chain is preferable because it has a high melting point and excellent heat resistance, weather resistance and acid resistance. Such polycarbonates include 2,2-bis (4-oxyphenyl) propane (also known as bisphenol A), 2,2-bis (4-oxyphenyl) butane, and 1,1-bis (4-oxyphenyl) cyclohexane And polycarbonates derived from bisphenols such as 1,1-bis (4-oxyphenyl) isobutane and 1,1-bis (4-oxyphenyl) ethane. Further, as another aromatic polycarbonate resin, a polycarbonate resin containing a polycarbonate component composed of poly (ester carbonate) may be mentioned. These are copolyesters having carbonate groups, carboxylate groups and aromatic carbocyclic groups repeated in a linear polymer chain. Preferably, at least some of the carboxylate groups are directly bonded to ring carbon atoms of the aromatic carbocyclic group. In addition to these aromatic polycarbonates, branched polycarbonates obtained by branching them are also exemplified. The above polycarbonate resins may be used alone or in combination of two or more.

The polyester resin in the PAT layer is preferably a linear polyester of a polycondensate of an aromatic dicarboxylic acid component and a diol component. Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, and diphenoxyethane dicarboxylic acid. Examples of the diol component include ethylene glycol, trimethylene glycol, tetramethylene glycol, neopentylene glycol, hexamethylene glycol, cyclohexane dimethylol, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, and 4,4 ′. -Bis (β-hydroxyethoxy) diphenyl sulfone, diethylene glycol and the like.

Examples of the polyester resin obtained from these aromatic dicarboxylic acids and diols include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycyclohexane terephthalate, and polybutylene terephthalate elastomer. , Polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate are particularly preferred. These polyester resins may be used alone or as a mixture of two or more kinds, or may be modified resins containing 50% by weight or more of these resins. Further, the foamed laminated sheet according to the present invention may be collected and recycled.

The polycarbonate resin in the PC layer generally has a large change in melt viscosity with respect to temperature and a very low melt tension at the time of extrusion, so that it is difficult to obtain a tension necessary for obtaining a closed-cell foam. It is. Therefore,
If a branched polycarbonate resin having improved melt tension is used, it is possible to obtain a foam having improved closed cells to some extent. Furthermore, in order to obtain a high magnification foam having high closed cells, a resin composition comprising a polycarbonate resin, a polyester resin and a crosslinking agent is used instead of the polycarbonate resin. In this case, by the crosslinking of the polyester-based resin, the melt tension is improved, the characteristics at the time of foaming are remarkably improved, and a foam having high closed cells and high magnification can be obtained. If this method is adopted, a foam having improved expansion ratio, open cell ratio and appearance can be obtained by using a generally used polycarbonate resin instead of a special grade polycarbonate resin. This method is particularly effective when the proportion of the polyester resin component is large.

When a resin composition comprising a polycarbonate resin, a polyester resin, a crosslinking agent, and at least one selected from metals and metal compounds is used, the crosslinking effect can be further enhanced, and the melt tension of the resin can be improved. The effect can be enhanced.

The crosslinking agent used in the present invention is preferably a compound having two carboxylic acid anhydrides in one molecule or a polyfunctional epoxy compound, and one or more selected from these may be used in combination. it can. Compounds having two carboxylic acid anhydrides in one molecule include pyromellitic anhydride, naphthalenetetracarboxylic anhydride, benzophenonetetracarboxylic anhydride, cyclopentanetetracarboxylic anhydride, ethylene glycol
(Anhydrotrimellitate) and glycerol (anhydrotrimellitate). Pyromellitic anhydride and benzophenonetetracarboxylic anhydride are particularly preferred.

Examples of the polyfunctional epoxy compound include diglycidyl terephthalate, diglycidyl orthophthalate, diglycidyl hexahydrophthalate, and tetrafunctional epoxy nitride (for example, TETRAD- manufactured by Mitsubishi Gas Chemical Company, Inc.).
D) polyethylene glycol diglycidyl ether,
Polypropylene diglycidyl ether, bisphenol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, hydrogenated BP-A
Diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether and the like,
Diglycidyl terephthalate, diglycidyl orthophthalate, diglycidyl hexahydrophthalate, and tetrafunctional epoxy nitride are particularly preferred.

The amount of the crosslinking agent to be used may be appropriately adjusted depending on the extrusion conditions, the desired expansion ratio, etc., but is preferably 0.01 to 5.0 with respect to 100 parts by weight of the polyester resin.
It is preferably about parts by weight. When the amount of the crosslinking agent is less than 0.01 part by weight, the effect of promoting the melt tension of the resin composition is not obtained. Conversely, when the amount is more than 5.0 parts by weight, the crosslinking reaction proceeds considerably, and This causes deformation, deterioration of appearance due to gelation, and the like, and furthermore, extrusion cannot be performed due to an increase in pressure.

The metals and metal compounds used in the present invention are not particularly limited, but may be any of the following:
Group III metals or compounds thereof. The Group I, II, and III metal compounds of the periodic table may be any of inorganic metal compounds and organic metal compounds. As inorganic metal compounds, sodium carbonate, potassium carbonate, zinc carbonate, magnesium carbonate, calcium carbonate, aluminum carbonate, sodium oxide, potassium oxide, zinc oxide,
Examples include magnesium oxide, calcium oxide, and aluminum oxide. Organic metal compounds include sodium stearate, potassium stearate, zinc stearate, magnesium stearate, calcium stearate, aluminum stearate, sodium montanate, calcium montanate, lithium acetate, sodium acetate, zinc acetate, magnesium acetate, Examples include calcium acetate, sodium cabrate, zinc cabrate, magnesium cabrate, calcium cabrate, aluminum cabrate, sodium myristate, aluminum myristate, calcium benzoate, potassium terephthalate, sodium ethoxide, potassium phenoxide and the like. Of these, Group I and Group II metal compounds are preferred, and Group I metal compounds are more preferred.

Such a metal or metal compound is used as a crosslinking agent 1
1 to 100 parts by weight, preferably 5 to 100 parts by weight
About 60 parts by weight are used.

The laminated foam sheet of the present invention is made of PC
And a PAT layer, and the laminated sheet satisfies the following formula. 1.4 <(Ta / Tb) <34 0.7 ≦ (Ta + Tb) ≦ 7 [wherein Ta represents the thickness (mm) of the PC layer and Tb
Represents the thickness (mm) of the PAT layer.] When the thickness ratio (Ta / Tb) is smaller than 1.4, that is, when the thickness of the PAT layer increases to near the thickness of the PC layer, heat resistance and heat molding Although deep drawing formability is improved,
The low-temperature impact resistance of the PAT layer is extremely reduced, and PA
Cracks are easily formed in the T layer. On the other hand, the thickness ratio (Ta /
When Tb) is larger than 34, that is, when the thickness of the PAT layer is considerably thinner than that of the PC layer, the effect of deep drawability at the time of heat molding cannot be obtained.

The total thickness of the foam laminated sheet is 0.7 to 7
mm is preferable, and 1-5 mm is more preferable. When the thickness of the foam laminated sheet is smaller than 0.7 mm, the strength of the molded container is reduced. On the other hand, if the thickness exceeds 7 mm, it is necessary to devise a method such as using a powerful far-infrared heater to uniformly heat the inside of the foam laminated sheet at the time of heat molding, and crystallization is considerable due to heating at a high temperature for a long time. Is promoted, and adverse effects such as poor elongation during molding are caused.

The thickness of the PAT layer in the foam laminated sheet is preferably 150 to 2000 μm, and 200 to 150 μm.
0 μm is more preferred. The thickness of the PAT layer is 150 μm
If it is less than 50 ° C., the PAT layer is melted by heat during thermal laminating to cause breakage, or P
It becomes difficult to uniformly extrude the thickness of the AT layer, and it is difficult to obtain the effects of the mold and the deep drawability of the obtained foamed laminated sheet during heat molding. On the other hand, if the thickness exceeds 2000 μm, the effect of improving the low-temperature impact resistance is not easily obtained even if the thicknesses of the PC layer and the PAT layer are balanced, and the PAT layer is easily cracked. The PC layer in the foam laminated sheet is
It is preferable to be made of a polycarbonate resin having very excellent cold resistance and to contain a crystalline polyester resin. Another object of the present invention is to improve the deep drawability at the time of heat molding, that is, in consideration of the reduction in the thickness of the side of the container and the prevention of strength reduction, wrinkles, and tears caused by the polyester resin component in the PC layer. The degree of crystallinity is appropriately adjusted according to the proportion of the polyester resin component, but is preferably less than 30%, more preferably less than 20%.

Further, low-temperature impact resistance at -30 ° C. or lower
The component ratio of the PC layer having heat resistance at 40 ° C. or more is as follows:
Preferably, the polycarbonate resin is 50 to 97% by weight and the polyester resin is 3 to 50% by weight, and the polycarbonate resin is 50 to 90% by weight and the polyester resin 1
The content is more preferably 0 to 50% by weight, particularly preferably 50 to 80% by weight of a polycarbonate resin and 20 to 50% by weight of a polyester resin. If the proportion of the polyester-based resin component is large, the low-temperature impact resistance of the PC layer is reduced, and the elongation at the time of heat molding is deteriorated with an increase in the polyester-based resin component.
Conversely, if the amount of the polyester-based resin component is too small, even if the crystallinity of the polyester-based resin component is
When the temperature exceeds, deformation of the foam laminated sheet is easily caused.

The crystallinity of the PAT layer in the foam laminated sheet is preferably less than 30%, as in the case of the PC layer, in consideration of the deep drawability during heat molding and the low-temperature impact resistance. % Is more preferable.

The degree of crystallinity of the PC layer and the PAT layer in a molded container formed by heating using the foamed laminated sheet is preferably in the range of 15 to 40%. When the crystallinity of each layer is less than 15%, the effect of heat resistance at 140 ° C. is hardly obtained. On the other hand, the crystallinity is 40%
In order to obtain a molding container exceeding, it is necessary to hold the foamed laminated sheet in a molding die adjusted at a temperature higher than the crystallization temperature for a long time during heat molding to promote crystallization, and the time per shot is extremely high. Long and costly.

The crystallinity of the polyester resin component in the PC layer and the crystallinity of the PAT layer are calculated by measuring a sample taken from a foamed laminated sheet or a container molded therefrom by a thermal method. . A differential scanning calorimeter (DSC) is used to measure the heat of cold crystallization and the heat of fusion of the polyester resin component in the PC layer or the PAT layer. (1) Sample treatment A 7 mg sample of each layer of the foamed laminated sheet was precisely weighed, and
Set it on the measuring section.

(2) Measurement conditions Apparatus: DSC200 manufactured by SEIKO Inc. Heating rate: 5 ° C./min (3) Calculation method Crystallinity of polyester resin component in PC layer: Heat of cold crystallization 100 ℃ point and 1
The straight line connecting the points at 40 ° C. is calculated as the baseline. The heat of fusion is calculated using a straight line connecting the 200 ° C. point and the 270 ° C. point of the measured DSC curve as a baseline.

Crystallinity of PAT layer: The calorific value of cold crystallization is calculated using a straight line connecting a point at 100 ° C. and a point at 181 ° C. in the measured DSC curve as a baseline. The heat of fusion is calculated using a straight line connecting the 200 ° C. point and the 270 ° C. point of the measured DSC curve as a baseline. The degree of crystallinity is determined by substituting the heat of cold crystallization and heat of fusion of each of the PC layer and PAT layer obtained by these methods into the following equation.

Crystallinity (%) of polyester resin component in PC layer = [heat of fusion (mj / mg) −heat of cold crystallization (mj / mg)] × [proportion (%) of polyester resin component / 100] ] × 100 / [140.1 (mj / m
g)] Crystallinity (%) of PAT layer = [heat of fusion (mj / mg)
-Cooling heat of crystallization (mj / mg)] x 100 / [140.
1 (mj / mg)]

Generally, the crystallization temperature of the polyester resin is in the range of 110 to 220 ° C. Therefore, P
Crystallinity of Polyester Resin Component in Layer C and PA
The preferred crystallinity of the T layer is achieved by adjusting the foamed laminated sheet within this temperature range.

As a method of controlling the degree of crystallinity, there are a method of controlling the production of the foamed laminated sheet (control method 1) and a method of controlling when the foamed laminated sheet is heat-formed (control method 2). When a foamed laminated sheet is heat-formed to produce a molded container, it is preferable to perform only the control method 2 in consideration of the deep drawability at the time of heat molding.

The control method 1 is, for example, extrusion molding which is a method for producing a foam formed by heating and kneading a resin composition and a foaming agent in an extruder, and extruding a molten gel obtained by this operation to a low pressure region. In the method, immediately after the molten gel at or above the crystallization temperature is extruded into a low pressure region, a medium whose temperature is controlled by heating (for example, air, hot water, steam, etc.),
Controlling the degree of crystallinity by adjusting the foam within the crystallization temperature range by using a heating temperature controlled mold (temperature control plate, temperature control roll, etc.) or a mandrel controlled by heating during the production of tubular foam How to

In the control method 2, for example, a foamed sheet extruded and foamed into a sheet shape by a circular die or a flat die is reheated to a crystallization temperature range by using a roll or a plate whose temperature is controlled by heating, and the degree of crystallinity is reduced. How to control. In addition, it is heated and softened in the heating step, and is pressed and molded in the molding die in the molding step,
In the heat molding to be a molded article, the degree of crystallinity can also be controlled by adjusting the foam to a crystallization temperature range in the heating step, the molding step, or both the heating step and the molding step. In consideration of formability, it is preferable to control the crystallinity in the forming step.

The method for producing the foamed laminated sheet of the present invention is not particularly limited, but a mixture obtained by previously dry-blending a resin component and an additive component such as a cross-linking agent or talc is melted and kneaded using an extruder. It is preferable from the viewpoint of production cost and the like that the material is continuously produced by a so-called extrusion molding method in which the material is extruded into a low-pressure region through a die (die) connected to the end of the extruder, foamed, and formed into a sheet. That is, the following production methods (a) and (b) using the extrusion molding method are suitably adopted. (A) The PC layer and the PAT layer are separately extruded into sheets using an extruder, and then directly thermally bonded by a heat lamination method to produce a laminated foamed sheet. At the same time, both sheets are softened at the time of heat molding, and molded with a desired mold to produce a molded container of a foam laminated sheet. (B) The molten gel of each layer melted and extruded almost simultaneously from the extruder tip for the PC layer and the PAT layer is merged in a multi-manifold die type die or a feed block connected to a single layer type die. After laminating and foaming, a laminated foam is manufactured by a so-called co-extrusion method in which the foam is extruded into a low-pressure region and foamed.

In the thermoforming, the sheet is heated and softened, pressed against a desired mold, and air in the gap between the mold and the material is eliminated.
It is performed by vacuum forming in which the sheet is closely adhered to the mold under atmospheric pressure, pressure forming in which the sheet is closely adhered to the mold by compressed air at or above atmospheric pressure, or molding using these together.

As the foaming agent, various known foaming agents can be used. The foaming agent is roughly classified into a physical foaming agent and a chemical foaming agent. Among them, the use of a physical foaming agent is preferable from the viewpoint of improving the expansion ratio. Physical blowing agents are further classified into inert gases, saturated aliphatic hydrocarbons, saturated alicyclic hydrocarbons, halogenated hydrocarbons, ethers, ketones, and the like. In the present invention, any of these may be used. it can. As typical examples, carbon dioxide, nitrogen and the like can be used as the inert gas, and propane,
Normal or isobutane, normal or isopentane or a mixture thereof can be used, and cyclohexane and the like can be used as a saturated alicyclic hydrocarbon, and methyl chloride, as a halogenated hydrocarbon,
Ethyl chloride and various chlorofluorocarbons can be used, and dimethyl ether and methyl tert-butyl ether can be used as ether, and acetone can be used as ketone. These foaming agents can be used alone or in combination of two or more.

The foaming ratio of the foamed laminated sheet is preferably in the range of 2 to 30 for each layer. Therefore, a foaming agent may be used in this range. If the expansion ratio is less than 2 times, the heat insulation performance and the effect of reducing the weight are poor, and the PAT layer has low impact strength at low temperatures. If the expansion ratio exceeds 30, the cell membrane becomes thin and closed cells are obtained. It is not preferable because the strength is low.

As long as the object of the present invention is not impaired, known additives such as a stabilizer, a flame retardant, an antistatic agent, and a coloring agent, which are added to a normal extruded foam, are used as a polycarbonate resin foam and And / or may be added to the polyester resin foam.

In order to foam the polycarbonate resin and / or the polyester resin smoothly, a bubble regulator may be added to the melt-kneaded product of each resin and a foaming agent, if necessary. Talc, silica,
Preferred are inorganic powders such as mica and mica, acidic salts of polycarboxylic acids, and mixtures of polycarboxylic acids with sodium carbonate or sodium bicarbonate. These foam control agents are 1
Species or two or more species may be used in combination. The addition amount is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 3.0 parts by weight, based on 100 parts by weight of each resin. 0.0
If the amount is less than 1 part by weight, it is difficult to obtain a sufficient bubble adjusting effect,
On the other hand, if it is more than 5.0 parts by weight, the cell diameter becomes too small, and the physical properties and moldability of the obtained foam are undesirably reduced.

[0041]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

Intrinsic viscosity: 0.300 g of polyethylene terephthalate resin was dissolved in 25 ml of orthochlorophenol with stirring at 140 ° C. for 1 hour, and this solution was cooled to 35 ° C.
Is calculated by measuring the solution viscosity with an Ostwald viscometer in a constant temperature layer of. Measurement method of thickness and density of each foam layer: The thicknesses of the PC layer and the PAT layer in the foam laminate sheet were each actually measured using a micrometer. The expansion ratio was determined by measuring the density of each foam layer, and calculating from the measured values and the raw material density of the foam layer using the following equation. However, since the raw material density of the PC layer is a mixture of a polycarbonate resin and a polyethylene terephthalate resin, it was determined from the specific density of each resin component constituting the mixture and the compounding ratio thereof. (Magnification of each foam layer) = (raw material density g / cm ³ ) / (density of each foam layer g / cm ³ )

Measurement method of open cell ratio: A cube having a side of about 2.5 cm is formed from the obtained foam, and its apparent volume is measured with a vernier caliper. Next, the true volume of the cube is measured using an air comparison hydrometer manufactured by Tokyo Science Corporation. Assuming that the obtained values and the apparent volume are A and the true volume is V, the open cell ratio is calculated by the following equation. Open cell ratio = (A−V) / A × 100

Evaluation of low-temperature impact resistance: long side 175 mm, short side 1
250 g of water in a tray-shaped container 25 mm deep and 26 mm deep
After placing in a constant temperature bath at −30 ° C. for 24 hours, a drop test was performed from the height of 80 cm in the same atmosphere, the state of the container was observed, and the container was evaluated according to the following criteria. ○: good (the container is not damaged) ×: the container is damaged

Heat resistance evaluation: long side 175 mm, short side 125 m
A tray-shaped molding container having a depth of 26 mm and a depth of 26 mm was heated at 160 ° C. for 10 minutes, the state of the molded product before and after heating was observed, and the degree of deformation was evaluated according to the following criteria. ：: good (not deformed) △: slightly deformed but retains its original shape ×: significantly deformed and does not retain its original shape at all

Evaluation of heat moldability: A single-shot molding machine was used to mold into a cup shape with a plug-assist molding die having a diameter of 80 mm and a depth of 70 mm, and the obtained molded container was evaluated according to the following criteria. did. (How to release the mold) ○: Good △: The corner of the mold is slightly sweet, but molding is possible ×: Almost no mold is produced (deep drawing formability) ○: Uniform and good in thickness △: Side is slightly thin Can be formed ×: Wrinkles and tears occurred on the side

Example 1 (1) Formation of PC Layer 100 parts by weight of a base resin composed of a polycarbonate resin having an average molecular weight of 25,000 (90% by weight) and a polyethylene terephthalate resin having an intrinsic viscosity of 0.75 (10% by weight) were crosslinked. 0.1 part by weight of pyromellitic dianhydride, 0.01 part by weight of sodium carbonate and 0.05 part by weight of talc as a foam regulator are mixed and supplied to a single screw extruder having a screw diameter of 65φ to be melt-kneaded. After that, 1kg of base resin
The melt-kneaded product obtained by injecting 0.20 mol of butane into an extruder was extruded into a cylindrical shape from a circular die (80 mm diameter, 0.5 mm slit) attached to the tip of the extruder, and the thickness was adjusted to 1 by a take-off machine. A balloon was formed in the interior of the tubular foam with air at room temperature while being taken up to a thickness of 0.0 mm, cooled with a mandrel in which water adjusted to 35 ° C. was circulated, and then incised to obtain a foam sheet. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer.

(2) Formation of PAT layer As in the case of the formation of the PC layer, 0.2 parts by weight of a crosslinking agent pyromellitic dianhydride and 0.2 parts by weight of sodium carbonate were added to 100 parts by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 1.07. 04
Parts by weight and 0.2 parts by weight of talc as a foam regulator were mixed, fed to a single screw extruder having a screw diameter of 65φ, melted and kneaded, and then 0.21 mol / kg of nitrogen resin was pressed into the extruder. Circular die (diameter 80φ, slit 0.5mm) with the obtained melt-kneaded product attached to the extruder tip
Extruded into a cylindrical shape, with a thickness of 0.6m
A balloon was formed inside the tubular foam with air at room temperature while taking it to m, and cooled and cut with a mandrel in which water adjusted to 35 ° C. was circulated to obtain a foam sheet. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PAT layer.

(3) Formation of Foam Laminated Sheet The surface of the obtained PC layer and the PAT layer to which the PAT layer adheres is approximately 45
Hot air heated to 0 ° C. was blown to soften the surface of each foamed layer, and then passed between rolls narrower than the total thickness of both foamed layers to obtain a foamed laminated sheet composed of two layers. PC
Table 1 shows the thickness ratio between the layer and the PAT layer. (4) Production of Molded Container Next, using a hot plate molding machine, the foamed laminated sheet is preheated to 170 ° C. in the heating step, and the tray shape and the cup are again heated to 170 ° C. in the molding step. It was molded into a shape to obtain a molded container for evaluation. Table 1 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

Example 2 (1) Formation of PC Layer The proportions of the polycarbonate resin and the polyethylene terephthalate resin were changed to 70% by weight and 30% by weight, respectively.
A PC layer was obtained in the same manner as in Example 1 except that the crosslinking agent pyromellitic dianhydride was used in an amount of 0.15 part by weight and sodium carbonate was used in an amount of 0.03 part by weight. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer. (2) Formation of PAT layer A PAT layer was obtained in the same manner as in Example 1. P obtained
Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the AT layer. Table 1 also shows the thickness ratio between the PC layer and the PAT layer.

(3) Formation of Laminated Foam Sheet A foam laminated sheet was obtained in the same manner as in Example 1. (4) Production of Molded Container Next, using a hot plate molding machine, the foamed laminated sheet is preheated to 180 ° C. in the heating step, and the mold is heated to 170 ° C. in the molding step in a tray shape and a cup shape. To obtain a molded container for evaluation. Table 1 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

Example 3 (1) Formation of PC layer Crosslinking agent pyromellitic dianhydride 0.18 parts by weight, butane was 0.25 mol per 1 kg of base resin. A PC layer was obtained in the same manner as in Example 2 except that the PC layer was taken out. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer. (2) Formation of PAT layer A PAT layer was obtained in the same manner as in Example 1. P obtained
Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the AT layer. Table 1 also shows the thickness ratio between the PC layer and the PAT layer.

(3) Formation of foam laminated sheet A foam laminated sheet was obtained in the same manner as in Example 1. (4) Production of Molded Container A molded container was obtained in the same manner as in Example 2. Mold release during hot forming and deep drawing formability, crystallinity of obtained molded container, low-temperature impact resistance evaluation of molded container and 160 ° C.
Is shown in Table 1.

Example 4 (1) Formation of PC Layer The proportions of the polycarbonate resin and the polyethylene terephthalate resin were changed to 60% by weight and 40% by weight, respectively.
0.16 parts by weight of crosslinking agent pyromellitic dianhydride, 0.04 parts by weight of sodium carbonate, 0.28 mol of butane per 1 kg of base resin, and 2.2 m in thickness with a take-off machine.
A PC layer was obtained in the same manner as in Example 3 except that the PC layer was taken out to obtain m. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer. (2) Formation of PAT layer A PAT layer was obtained in the same manner as in Example 1, except that the PAT layer was taken up to a thickness of 1.0 mm with a take-up machine. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PAT layer. Table 1 also shows the thickness ratio between the PC layer and the PAT layer.

(3) Formation of Laminated Foam Sheet A laminated foam sheet was obtained in the same manner as in Example 1. (4) Production of Molded Container Next, using a hot plate molding machine, the foamed laminated sheet is preheated to 185 ° C. in the heating step, and the mold is heated to 170 ° C. in the molding step to form a tray and a cup. To obtain a molded container for evaluation. Table 1 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

Example 5 (1) Formation of PC layer A PC layer was obtained in the same manner as in Example 4. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer. (2) Formation of PAT layer A PAT layer was obtained in the same manner as in Example 1 except that the PAT layer was taken out to a thickness of 0.4 mm with a take-up machine. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PAT layer. Table 1 also shows the thickness ratio between the PC layer and the PAT layer.

(3) Formation of Laminated Foam Sheet A laminated foam sheet was obtained in the same manner as in Example 1. (4) Production of Molded Container A molded container was obtained in the same manner as in Example 4. Mold release during hot forming and deep drawing formability, crystallinity of obtained molded container, low-temperature impact resistance evaluation of molded container and 160 ° C.
Is shown in Table 1.

Example 6 (1) Polycarbonate resin (PC) having an average molecular weight of 25,000 (70% by weight) and polyethylene terephthalate resin (PET) having an intrinsic viscosity of 0.75 (30% by weight)
0.18 parts by weight of a crosslinking agent pyromellitic dianhydride and 0.08 parts by weight of sodium carbonate were added to 100 parts by weight of a base resin composed of
After mixing 3 parts by weight and 0.05 part by weight of talc as a cell regulator, supplying the mixture to a single screw extruder having a screw diameter of 65φ and melt-kneading, extruding 0.25 mol / kg of butane as a foaming agent It was press-fitted into a machine, and was fed into a joining die at a rate of 85 kg / hour. The extruded foam forms the PC layer.

(2) With respect to 100 parts by weight of polyethylene terephthalate resin (PET) having an intrinsic viscosity of 1.07, 0.2 parts by weight of a crosslinking agent pyromellitic dianhydride, 0.04 parts by weight of sodium carbonate, and foam control 0.20 parts by weight of talc as an agent is mixed, supplied to a single-screw extruder having a screw diameter of 50φ, and melt-kneaded. Then, 0.18 mol / kg of nitrogen as a foaming agent is injected into the extruder and extruded. 35
The mixture was introduced into the joining die at a rate of kg / hour. The extruded foam forms a PAT layer.

(3) The resin joined by the joining die is poured into a circular die (80 mm in diameter, 0.5 mm slit), extruded into a cylindrical shape from the slit, and the inside of the tubular foam is taken out by a take-off machine. A balloon was formed with air at room temperature, cooled with a mandrel in which water adjusted to 35 ° C. was circulated, and then incised to obtain a foamed laminated sheet. Table 1 shows the thickness, expansion ratio, crystallinity, and open cell ratio of each layer of the obtained foamed laminated sheet. Table 1 shows the thickness ratio of each layer. (4) Manufacture of molded container Using a hot plate molding machine, the foamed laminated sheet is heated at 18
It was preheated to 0 ° C., and was molded into a tray shape and a cup shape with a mold heated to 170 ° C. in a molding step, to obtain a molded container for evaluation. Table 1 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

[0061]

[Table 1]

Comparative Example 1 (1) Formation of PC Layer A polycarbonate resin foam sheet was obtained in the same manner as in Example 3, except that the PC layer was taken off so as to have a thickness of 1.7 mm. Table 2 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PC layer. (2) Production of molded container A molded container was obtained in the same manner as in Example 3 from the obtained foamed sheet. Table 2 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

Comparative Example 2 (1) Formation of PAT Layer A foamed polycarbonate resin sheet was obtained in the same manner as in Example 1 except that the PAT layer was taken out so as to have a thickness of 1.7 mm. Table 2 shows the thickness, expansion ratio, crystallinity, and open cell ratio of the obtained PAT layer. (2) Production of molded container A molded container was obtained in the same manner as in Example 1 using the obtained foamed sheet. Table 2 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

Comparative Example 3 (1) Formation of PC Layer A PC layer was obtained in the same manner as in Example 3. (2) Formation of PAT layer A PAT layer was obtained in the same manner as in Example 4. (3) Formation of foam laminated sheet A foam laminated sheet was obtained in the same manner as in Example 1. (4) Production of molded container A molded container was obtained in the same manner as in Example 2 from the obtained foamed sheet. Table 2 shows the appearance of the mold and the deep drawability during heat molding, the crystallinity of the obtained molded container, the low-temperature impact resistance evaluation of the molded container, and the heat resistance evaluation at 160 ° C.

[0065]

[Table 2]

[0066]

The foamed laminated sheet of the present invention retains the excellent low-temperature impact resistance of the foamed polycarbonate resin layer and has heat resistance and moldability during heat molding, especially deep molding, by the laminated foamed polyester resin layer. The drawability has been dramatically improved. Further, a container molded using this sheet is suitable as a container for cooking frozen foods.

 ──────────────────────────────────────────────────の Continuing on the front page F term (reference) 4F100 AA02B AA08 AB01B AC10 AH02H AK42A AK42B AK42J AK45B AK45J AL01B AL05B BA02 BA12 BA15 BA25 CA02B DA01 DJ01A DJ01B GB16 JA20A JA20B JJ03 JK10 JL02CF072J032CF042 CG011 DE057 DE087 DE107 DE147 DE227 DE237 DE247 EG027 EG037 EG047 EL136 FD143 FD146 FD207 GG01

Claims (5)

[Claims] 1. A foam laminated sheet in which a polycarbonate resin foam layer and a polyester resin foam layer are laminated, wherein each foam layer satisfies the following equation. 1.4 <(Ta / Tb) <34 0.7 ≦ (Ta + Tb) ≦ 7 [wherein, Ta is the thickness (mm) of the polycarbonate resin foam layer, and Tb is the thickness (m) of the polyester resin foam layer.
m). ] 2. The foam laminated sheet according to claim 1, wherein the polycarbonate resin foam layer is formed by foaming a resin composition comprising a polycarbonate resin, a polyester resin and a crosslinking agent. 3. The polycarbonate resin foam layer according to claim 1, wherein the resin composition comprises at least one selected from the group consisting of a polycarbonate resin, a polyester resin, a crosslinking agent, and a metal and a metal compound. Foam laminated sheet. 4. The foam laminated sheet according to claim 2, wherein the crosslinking agent is at least one selected from a compound having two carboxylic anhydrides in one molecule and a polyfunctional epoxy compound. 5. A molded container formed by molding the foamed laminated sheet according to claim 1 so that the polyester resin foamed layer is on the inside.