JPH09141772A - Styrene resin laminated foam sheet for thermal molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrene resin laminated foam sheet for thermal molding capable of effectively preventing 'drawdown' phenomenon from being generated in a heating zone and also preventing an uneven heating action or discoloration from occurring, and making a thermal molding with excellent physical property and presentable appearance. SOLUTION: This styrene resin laminated foam sheet is a laminated foam sheet of a styrene resin foam sheet and a high-impact polystyrene resin sheet. The maximum value of the thermal contraction load of the high impact polystyrene resin sheet is 10g/5mm wide or more, at least in the longitudinal direction of the high-impact polystyrene resin sheet, and the coefficient of thermal contraction of the laminated foam sheet after 40sec. of heating at 145 deg.C is set to 0-25% in either of the extrusion or the widthwise direction of the styrene resin foam sheet. Thus it is possible to significantly reduce the generation of 'drawdown' phenomenon at the time of thermal molding and consequently, obtain a thermal molding with excellent physical property and presentable appearance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin laminated foam sheet for thermoforming, which is suitable for forming thermoformed articles such as containers. More specifically, it relates to a method for continuously forming thermoformed articles. The present invention relates to a styrene-based resin laminated foam sheet for thermoforming suitable for effectively preventing sagging of a sheet that is likely to occur at times, and as a result, preventing the occurrence of thermoforming defects and obtaining a thermoformed article excellent in strength and appearance. .

[0002]

2. Description of the Related Art Conventionally, styrene resin foam sheets have been widely used for thermoforming of containers and the like, but molded products formed from styrene resin foam sheets have a problem in impact resistance and are easily damaged. There was a problem. For the purpose of improving the impact resistance of a molded product obtained from such a styrene resin foam sheet, a high impact polystyrene resin (hereinafter, referred to as HIPS) is added to a styrene resin foam sheet (hereinafter sometimes abbreviated as PSP). It may be abbreviated.) A laminated foam sheet in which sheets are laminated is used as a thermoforming sheet. The HIPS sheet is a PS made of general-grade polystyrene resin (GPPS).
HIP because it has a whiter appearance than P.
Laminating the S sheet on the PSP also has the effect of improving the appearance of the PSP.

[0003]

The laminated foam sheet as described above is conventionally manufactured by a method of extrusion-laminating HIPS on a PSP manufactured in advance. Such a conventional styrene resin for thermoforming is used. Laminated foam sheet,
There were the following problems in hot molding.

That is, when a container or the like is continuously molded using the above-mentioned laminated foam sheet, both side edges of a long laminated foam sheet are clamped and conveyed to a heating zone, and both sides of the sheet are heated with a heater in the heating zone. After the sheet is softened to a moldable state, it is transferred to the molding zone and molded into a predetermined shape continuously. However, in the case of the conventional styrene-based resin laminated foam sheet, when it is heated in the heating zone, it is likely to sag due to expansion and its own weight (this sagging phenomenon is referred to as drawdown). In particular, the molded product to be obtained is a relatively deep-drawn molded product such as a bowl shape (the ratio of the diameter of a circle having the same area as the area inside the opening of the molded product to the depth of the molded product is 0.25 or more). , Especially a molded product of 0.4 or more), the secondary thickness of the PSP in the laminated sheet is usually (secondary foaming occurs in the PSP when the laminated sheet is heated in the heating zone and the thickness of the PSP is The thickness of the PSP before heating is referred to as the secondary thickness.
It is said that it should be 5 times or more, preferably 2.0 times or more. However, in order to increase the thickness of the PSP, it is necessary to lengthen the heating time of the laminated sheet to sufficiently heat it, but there is a problem that the drawdown increases as the heating time increases.

The heaters for heating in the heating zone are usually arranged on the upper and lower sides of the sheet so that the sheet can be uniformly heated from the upper and lower surfaces. However, when a large drawdown occurs in the laminated foamed sheet, the laminated sheet is laminated. Since the distance between the foamed sheet and the heater changes and the lower surface side of the sheet is closer to the heater, it is in an overheated state, and the upper surface side of the sheet is more likely to be in an insufficient heating state because it is separated from the heater.
Therefore, due to uneven heating of the laminated sheet, there are problems in that the state of the obtained molded product is different, the thickness is uneven and the strength is poor, and the appearance is unsatisfactory. When a drawdown occurs on a sheet, there is a case where a wavy phenomenon (called a corrugation) occurs or there is a case where it does not occur. However, when a corrugation occurs, heating unevenness is further promoted, and the above-mentioned problems caused by heating unevenness are more serious. There is a risk of becoming.

More recently, thermoforming machines having a short distance between the upper and lower heaters in the heating zone (about 200 to 300 mm) have been used (the reason why a molding machine having a shorter distance between heaters is used is not clear. ). However, when such a molding machine is used, if the drawdown of the sheet becomes large, there is also a problem that the lower surface of the sheet comes into contact with the lower heater in the heating zone, and the contacted surface leaks into a keloid shape and causes poor appearance. It was

As one method for preventing drawdown, there is a method for reducing the thermal expansion force of PSP constituting the laminated foam sheet. As one specific example thereof, it is possible to form the laminated foam sheet at a time of 2 months or more after manufacturing the PSP forming the laminated foam sheet. However, in this method, a laminated foam sheet or PS
After manufacturing P, it must be kept in stock for a long period of time, which causes a problem of high storage cost. On the other hand, there is also a method in which PSP is extruded and foamed at a high temperature to quickly reduce the thermal expansion force of PSP without incurring the above storage cost. However, since the closed cell ratio of PSP extruded and foamed at a high temperature is lowered, there is a problem that the strength of the PSP is lowered, and the strength of the molded product is also lowered.

Drawdown can also be prevented by making the blow-up ratio extremely large when manufacturing the PSP and giving the PSP a large heat shrinkability. However, such a PSP is not a preferable method because the thermoformability thereof is extremely deteriorated and holes or cracks are likely to occur in the thermoformed product.

Further, it is possible to extend a clamp interval of a conveying device that clamps and conveys both side edges of the laminated foam sheet, and expands the clamp interval when drawdown occurs due to heating of the laminated foam sheet in the heating zone. Therefore, a method of absorbing the drawdown can be considered. However, this method needs to be replaced with a special transporting device different from the conventional transporting device, and complicated work that requires controlling the expansion ratio of the clamp interval according to the degree of drawdown, or There is a problem that a special control device must be added. Therefore, it can be said that this method, in which the conventional thermoforming machine cannot be used as it is, is extremely difficult for a trader who uses a general-purpose thermoforming machine to perform molding.

[0010] The present invention has been made in view of the above points,
Even when molding is performed using a conventional general-purpose thermoforming machine, it is possible to effectively prevent the occurrence of drawdown in the heating zone, prevent uneven heating and discoloration of the sheet, and physical properties,
An object of the present invention is to provide a styrene-based resin laminated foam sheet for thermoforming, which enables to obtain a thermoformed article having an excellent appearance.

[0011]

That is, the styrene resin laminated foam sheet for thermoforming of the present invention is a laminated foam sheet of a styrene resin foam sheet and a high impact polystyrene resin sheet, which is a high impact polystyrene resin sheet. The maximum value of heat shrinkage load is 1 at least in the longitudinal direction of the high impact polystyrene resin sheet.
The heat shrinkage ratio of the laminated foam sheet having a width of 0 g / 5 mm or more and heating at 145 ° C. for 40 seconds is 0 in both the extrusion direction and the width direction of the styrene resin foam sheet.
It is characterized by being 25%.

In the present invention, the maximum value of the heat shrinkage load of the high impact polystyrene resin sheet is preferably 11 g / 5 mm width to 20 g / 5 mm width at least in the longitudinal direction of the high impact polystyrene resin sheet. In addition, the high-impact polystyrene resin sheet is an unstretched high-impact polystyrene resin layer,
It is preferably a laminated sheet with a stretched high-impact polystyrene resin film, and the non-stretched high-impact polystyrene resin layer side is laminated on the styrene resin foam sheet side.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As the styrene resin which is a base resin of PSP constituting the laminated foam sheet of the present invention, a styrene homopolymer, a styrene copolymer containing styrene as a main component, or a mixture thereof. Alternatively, a mixed resin in which one or more selected from the group of the styrene homopolymer and the styrene-based copolymer as the main component is mixed with another resin or rubber as an auxiliary component, and the like can be mentioned. The styrene-based copolymer, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, styrene-
A butadiene-acrylonitrile copolymer etc. are mentioned. Examples of the resin or rubber mixed as the above-mentioned subcomponent include polyphenylene oxide, butadiene rubber, butadiene-styrene copolymer rubber and the like.

The styrene resin preferably has a Vicat softening point (JIS K6870) of 105 ° C. or lower. Usually, a styrene-based resin having a Vicat softening point of more than 105 ° C. is not preferable because a substance that reduces the elongation of PSP during thermoforming is mixed in a relatively large amount or copolymerized. However, if the Vicat softening point is 105 ° C. or lower, even if a substance that reduces the elongation during thermoforming of PSP is mixed or copolymerized in the styrene resin, thermoforming of PSP There is almost no fear of impeding sexuality.

PSP is prepared by supplying the above-mentioned styrene resin, a foaming agent, a cell regulator and, if necessary, various additives such as a heat stabilizer, a UV absorber, an antioxidant and a colorant into the extruder. , Melt-kneading at a temperature equal to or higher than the melting temperature of the styrene-based resin, and then extruded from an annular die to form an annular foam, while expanding the diameter of the annular foam while cooling,
Next, the annular foam is manufactured by a method such as cutting open from one end along the extrusion direction and developing into a sheet shape. The PSP used in the present invention preferably has a thickness of 1.5 to 3.0 mm and a density of 0.75 to 0.15 g / cm ³ .

As the foaming agent used in the production of the PSP, a volatile foaming agent, an inorganic gas type foaming agent, a decomposition type foaming agent, etc. may be used alone or in combination of two or more. As the volatile foaming agent, for example, propane, normal butane, isobutane, pentane, aliphatic hydrocarbons such as hexane, cyclobutane, cycloaliphatic hydrocarbons such as cyclopentane, trichlorofluoromethane, dichlorodifluoromethane, 1 , 2-Dichloro-1,1,2,2-tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1-difluoroethane, 1,1-dichloro-2,2,2-trifluoroethane, methyl Examples thereof include halogenated hydrocarbons such as chloride, ethyl chloride and ethylene chloride. As the inorganic gas type foaming agent, an inert gas such as carbon dioxide, nitrogen or air is used. Examples of the decomposition-type foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, sodium bicarbonate and the like. However, it is desirable to use a volatile foaming agent as the main foaming agent from the viewpoint of improving the secondary foaming property during heating prior to thermoforming of PSP. The amount of foaming agent added is
Since the amount varies depending on the type of the foaming agent, the base resin, the target expansion ratio, etc., the addition amount is selected according to the type of the foaming agent and the base resin so that the desired expansion ratio is obtained.

As a foam regulator used together with a foaming agent in foaming PSP, inorganic powder such as talc and silica, an acid salt of polyvalent carboxylic acid, a reaction of polyvalent carboxylic acid with sodium carbonate or sodium bicarbonate. A mixture etc. are mentioned. The addition amount of the cell regulator is usually about 5 parts by weight per 100 parts by weight of the resin.

The base resin of the HIPS sheet laminated on the PSP is composed of a styrene component and a rubber component, and when the total amount of both is 100% by weight, the styrene component 65 to 65 is used.
A styrene resin composed of 98% by weight and a rubber component of 35 to 2% by weight, and specific examples include the following. Random copolymer resin consisting of styrene component and rubber component, block copolymer resin, graft copolymer resin,
Alternatively, a mixture of two or more of these copolymer resins. A mixture of the above resin and a styrene homopolymer. A mixture of styrene homopolymer and rubber (including thermoplastic elastomer). A mixture of the above resin or a resin thereof and rubber (including a thermoplastic elastomer). However, in the above-mentioned styrene resin, which is the base resin of the HIPS sheet, the value of Izod impact strength (JIS K6871) is 3. from the viewpoint of imparting impact resistance and strength to the laminated foam sheet and the thermoformed product thereof. 0-10kg
-Cm-cm ^-1 , preferably 3.5-9 kg-
cm.cm ^-1 should be used.

In the present invention, the HIPS sheet needs to have a maximum value of heat shrinkage load of 10 g / 5 mm width or more in at least the longitudinal direction of the HIPS sheet (which is the same as the extrusion direction). When the heat shrinkage load in the longitudinal direction of the HIPS sheet is less than 10 g / mm, the drawdown generation amount of the sheet is large at the time of heating when forming the laminated foam sheet, and as a result, the various problems described above occur. There is fear. In the longitudinal direction of the HIPS sheet, the maximum value of the heat shrinkage load of the HIPS sheet is 10 above.
When the width is g / 5 mm or more, drawdown of the laminated foam sheet can be effectively reduced or prevented. In order to further reduce the drawdown of laminated sheets,
The maximum value of the heat shrinkage load in at least the longitudinal direction of the HIPS sheet is preferably 11 g / 5 mm width or more.
However, if this value is too large, there is a high risk that the sheet will come off the clamp during thermoforming of the laminated foam sheet or that elongation failure will occur during thermoforming, so the maximum value of the heat shrinkage load of the HIPS sheet is 20 g / The width is preferably 5 mm or less.

In the present invention, the heat shrinkage load of the HIPS sheet is the heat shrinkage load of the HIPS sheet after being laminated on the PSP. The heat shrinkage load of HIPS is
Although it is developed by the stretching treatment at the time of manufacturing the HIPS sheet, the heat shrinkage load before the HIPS is laminated on the PSP and the heat shrinkage load after the HIPS is laminated on the PSP are unlikely to be the same value. The reason is that when HIPS and PSP are laminated, a method of laminating by heat bonding is usually adopted. However, depending on the method of heat bonding and heating conditions at that time, H
It is considered that the degree of orientation during stretching of the IPS sheet may be relaxed. HI due to heating during stacking
The degree of relaxation of the orientation of the PS sheet during stretching is also affected by the difference in the thickness of the HIPS sheet. Therefore, in the present invention, the heat shrinkage load of the HIPS sheet is HI.
The value after PS is laminated on PSP is adopted, and the heat shrinkage load of the laminated HIPS sheet is measured by peeling the HIPS sheet from the laminated sheet.

The surface layer portion of PSP and its vicinity are peeled off and adhered to the surface of the HIPS sheet peeled from the laminated sheet, and such a HIPS sheet can be used as it is to measure the heat shrinkage load. . Generally, PSP is extruded and foamed in a cylindrical shape, and the cylindrical foamed body is manufactured so that its diameter can be expanded while the surface is cooled.
Orientation due to stretching occurs on the SP surface. However, the degree of orientation is not so large, and HIP on the surface.
When the S sheet is heat-bonded, the heat at that time relaxes the orientation of the PSP surface to a negligible state. Therefore, it can be said that the measurement value is not substantially affected even if the heat shrinkage load is measured with part of the PSP peeled off and attached to the surface of the HIPS sheet peeled from the laminated sheet.

To measure the heat shrinkage load, a length of 15 mm and a width of 5 were obtained from a HIPS sheet separated from the laminated sheet.
mm samples are cut out and thermomechanical analyzers (eg,
Shimazu Corporation thermomechanical analyzer: TMA-50 type etc. was fixed to the chuck at both ends in the longitudinal direction of the sample with a chuck distance of 10 mm (at this time, the ambient temperature was 30 ° C. and the chuck between the samples was fixed). The initial load is set to 6 g / 5 mm width.) Then, the sample tries to shrink when the temperature is raised and heated at a rate of 10 ° C./min, but the chuck distance is always kept at 10 mm. The value measured as the load necessary to prevent the shrinkage of the sample is the heat shrinkage load. In the present invention, H
Maximum heat shrinkage load of IPS sheet (Unit: g / 5m
The m width) is the maximum value of the heat shrinkage load values obtained by heating and heating the sample from 30 ° C. to 150 ° C. (however, the sample is heated from 30 ° C. to 150 ° C.). When noise appears near the maximum value of the curve of temperature and heat shrinkage load obtained by heating, the noise portion is corrected by the curve passing through the center of the noise, and the corrected maximum value is obtained.). In order to measure the heat shrinkage load in the longitudinal direction of the HIPS sheet, the lengthwise direction of the sample should be aligned with the lengthwise direction of the HIPS sheet. To measure the heat shrinkage load in the width direction of the HIPS sheet, the length of the sample should be measured. The direction may be the same as the width direction of the HIPS sheet.

Since the heat shrinkage load of the HIPS sheet is often different before and after it is laminated on the PSP as described above, the heat-bonding method and its conditions adopted in the production of the laminated sheet, and the HIPS sheet used. It is important to conduct a preliminary experiment according to the type, thickness, degree of stretching, etc. to understand the tendency of the change in the heat shrinkage load before and after the HIPS sheet is laminated on the PSP. By grasping the tendency of the change in the heat shrinkage load of the HIPS sheet, it becomes easy to maintain the heat shrinkage load of the HIPS sheet after being laminated on the PSP within the range of the present invention.

The HIPS sheet used in the present invention preferably has a thickness of at least 70 μ from the viewpoint of improving the impact resistance and strength of the thermoformed product. From the viewpoint of cost and the like, the HIPS sheet is The upper limit of the thickness is preferably 190μ.

In the laminated foamed sheet of the present invention, the heat shrinkage ratio of the laminated foamed sheet after heating at 145 ° C. for 40 seconds coincides with the extrusion direction of the PSP forming the laminated foamed sheet (the longitudinal direction of the laminated foamed sheet). ) And in the width direction (which coincides with the width direction of the laminated foam sheet), it is necessary to be 0 to 25%. When the heat-shrinkage rate of the laminated foam sheet is smaller than 0% (when the measured value of the heat-shrinkage rate is negative, that is, when the sheet expands by heating), the heating zone is used when thermoforming the laminated foam sheet. When the drawdown of the laminated foamed sheet is increased, and the heat shrinkage ratio exceeds 25%, cracks are likely to occur in the thermoformed product during thermoforming. While further reducing the drawdown of the laminated foam sheet in the heating zone,
In order to further prevent cracking of the thermoformed product, the heat shrinkage ratio of the laminated foam sheet is determined by the PSP extrusion direction (HI).
It coincides with the extrusion direction of the PS sheet. ), Width direction (HIP
It matches the width direction of the S sheet. ) Is preferably 3 to 15%.

The heat shrinkage ratio of the laminated foamed sheet depends on the heat shrinkage load of the HIPS sheet constituting the laminated foamed sheet, the degree of stretching of the PSP, the total pressure between the foaming agent and the air in the PSP, and the like. To be affected. The higher the heat shrinkage load of the HIPS sheet, the higher the degree of stretching of the PSP, and the lower the total pressure of the foaming agent and air in the PSP, the higher the heat shrinkage rate of the laminated foam sheet, and vice versa. Becomes smaller. It is also affected by differences in PSP thickness, expansion ratio, and the like. Therefore, the heat shrinkage load of the HIPS sheet before lamination, the total pressure of the foaming agent in the PSP and the air, the degree of stretching of the PSP, and the heat shrinkage rate of the laminated sheet after the HIPS sheet and the PSP are laminated by preliminary experiments. It is important to understand the relationship with
Is important for surely obtaining the laminated foam sheet.

An air circulation oven, such as "PERFECT OV" manufactured by Tabai Espec Co., Ltd., is used to measure the heat shrinkage rate.
EN PH-200 "(trade name) can be used. With respect to the heat shrinkage rate, a square sample having a side of 20 cm was cut out from the laminated foam sheet while keeping the thickness of the laminated foam sheet so that the vertical and horizontal sides were aligned with the extrusion direction and width direction of the PSP. The sample is lightly sandwiched from both sides by a coarse wire mesh (opening 1-2 cm), and in this state, it is put in an air circulation oven heated to 145 ° C. and heated for 40 seconds, then taken out of the oven and each side of the sample is removed. The length is measured and calculated from this measured value. The heat shrinkage ratio of the laminated foam sheet is a value obtained by dividing the difference between the length before heating the sample (20 cm) and the length after heating by the length before heating, and multiplying by 100 to obtain the PSP of the sample.
The calculation is performed for each of the direction that matches the extrusion direction and the direction that matches the width direction.

In order to stack the HIPS sheet on the PSP, the HIPS sheet side is heated by a heating roll, and the HIPS is heated by this heating roll and the nip roll arranged on the PSP side.
When a so-called thermal laminating method is adopted in which the sheet and the PSP are pressed and heat-bonded to each other, the thickness of the HIPS sheet is 5
If it exceeds 0 μ, sufficient adhesive strength may not be obtained. As described above, H in the laminated foam sheet of the present invention
Since the IPS sheet preferably has a thickness of at least 70 μm or more, the method for obtaining the laminated sheet of the present invention is not the thermal lamination method, but the PSP and stretched HIP.
It is preferable to use a method in which molten HIPS is extruded and laminated between the film and the S film to laminate the both. A method for obtaining a laminated foam sheet by this method will be described below with reference to the drawings.

In FIG. 1, 1 is PSP, and H is PSP1.
To improve the moldability of PSP1 prior to stacking the IPS sheets (to reduce stress on the surface)
The heat treatment of can be performed as needed. As a method of performing the heat treatment, a method of winding the PSP1 around the surface of the heating roll 2 to heat it and pressing the PSP1 with the heating roll 2 and the pinching roll 3 is adopted. PSP
1 is surface-contacted with the heating roll 2 in a range from a point A to a point B, and an angle formed by a line segment connecting the center of the heating roll 2 to the points A and B: θ ( 20) to 1 for a heating roll having a diameter of 200 mm.
15 to 15 with a heating roll of 80 ° and a diameter of 300 mm
10 to 130 with a heating roll of 0 ° and a diameter of 400 mm
It is about °. Holding angle: θ is tension rolls 4a, 4
It can be adjusted by moving b up and down.

PS subjected to the heat treatment as described above
In order to laminate the stretched HIPS film 5 on P1, as shown in the drawing, the PSP1 and the HIPS film 5 are squeezed by the pressure rolls 6a and 6b.
Between the HIPS film 5 and the HIPS film 5, the molten HIPS 8 is extruded into a sheet shape from the extruder 7, and then the pressure roll 6a.
By sandwiching the PSP1 and the HIPS film 5 between the and 6b, PS in the molten HIPS8 is used as an adhesive.
The laminated foam sheet 9 can be obtained by laminating the P1 and the HIPS film 5.

In the laminated foam sheet 9 obtained by this method, the layer of the HIPS sheet in the laminated foam sheet of the present invention is composed of a layer made of the stretched HIPS film 5 and a solidified product of molten HIPS 8 used as an adhesive. The composite sheet is composed of an unstretched or slightly stretched HIPS layer in the extrusion direction (hereinafter referred to as a substantially unstretched HIPS layer), and is substantially unstretched HI.
It has a configuration in which the PS layer is located on the PSP1 side. In this case, the heat shrinkage load of the HIPS sheet is
It is obtained by peeling the composite sheet of HIPS from the laminated foam sheet 9 and measuring the composite sheet as described above. Therefore, since the layer made of HIPS used as the adhesive is not stretched practically, the HIPS film 5 is made to have the heat shrinkage load of the HIPS sheet (composite sheet) to the above-mentioned value. It is necessary to use a stretched HIPS film.

When the laminated foam sheet of the present invention is produced by the extrusion laminating method as described above, the heat shrinkage load of the HIPS sheet in the obtained laminated foam sheet is caused by the stretched HIPS film 5 or mainly HI.
It is expressed by the PS film 5. Therefore, when the thickness of the HIPS film 5 to be laminated is too thin, it becomes difficult to obtain a desired heat shrinkage load value, and wrinkles easily occur on the HIPS film 5 during lamination. On the other hand, if the HIPS film 5 is too thick, the cost will increase. Therefore, as the stretched HIPS film 5 to be laminated by the extrusion laminating method, those having a thickness of 15 to 50 μ, particularly 25 to 40 μ are preferable.

When the laminated foam sheet is manufactured by the extrusion laminating method described above, the pressure roll 6b of the pair of pressure rolls 6a and 6b which is in contact with the HIPS film 5 is a cooled roll. A pressure roll 6 in which the PSP 1 and the HIPS film 5 are preferably laminated with the HIPS 8 as an adhesive, and then the laminated sheet 9 is cooled.
It is preferable to let it be held in b. By doing so, it is possible to reduce the decrease in the orientation of the stretched HIPS film 5. From the same viewpoint, it is preferable that the extruding position of the melted HIPS 8 be slightly closer to the PSP 1 side.

The HIPS film 5 may be either a heat-treated surface or a non-heat-treated surface of the PSP1, but when the HIPS film 5 is laminated on the non-heat-treated surface side of the PSP1 as in the example shown in FIG. In the sheet, the slip property of the PSP side surface is also improved. Thermoformed products such as containers thermoformed from such laminated foam sheets have good slipperiness between the thermoformed products when a plurality of thermoformed products are stacked and stored and taken out one by one from this state. Therefore, there is little possibility that troubles such as two or more pieces being taken out will occur. The container obtained by thermoforming so that the heat-treated surface side of the PSP in the laminated foamed sheet is on the outside is conveyed while repeating the movement and stopping of the container, and the products are sequentially filled in the container during the conveying process. Even if it involves a process of stopping the transfer of the container while the container is slid on the conveying means like the automatic filling and packaging method, the container has a good slidability on the bottom surface side, Even when the transfer is stopped in the slipped state, there is little risk that the containers will overlap with each other or will fall over.

In order to improve the slipperiness of a thermoformed article such as a container thermoformed from a laminated foam sheet, the PSP side surface of the laminated foam sheet is heat treated as described above,
A method of applying a lubricant such as silicone oil to one side or both sides of the laminated foam sheet is also effective. In particular, in order to make the PSP side surface of the laminated foam sheet more slippery, it is desirable to use both methods together. When both methods are used in combination, heat treatment of the PSP side surface of the laminated foam sheet is usually preceded. In particular, when a lubricant such as silicon oil is applied to the HIPS film 5 side of the laminated foam sheet, not only the sliding property improving effect but also the printing property improving effect is imparted. Therefore, it is very effective when printing is performed on the surface of the HIPS film 5 of the thermoformed product which is thermoformed so that the HIPS film 5 side of the laminated foam sheet is the outside.

Lubricants such as silicone oil are usually used.
It is diluted with water, applied to the surface of the laminated foam sheet by a roll coater or the like, and dried. This drying may be performed after winding the laminated foamed sheet into a roll after the application.

The above-mentioned laminated foamed sheet is heated and softened in the heating zone and then molded by a conventional method. As the forming method, vacuum forming, pressure forming, and applications of these, free drawing forming, plug and ridge forming, ridge forming, matched forming, straight forming, drape forming, reverse draw forming, air slip forming, Plug-assist molding, plug-assist reverse road molding, etc., or a method combining these is adopted.

[0038]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Example 1 A PSP (width 1040 mm) having a thickness of 2.3 mm and a basis weight of 250 g / m ² and having a polystyrene resin having a Vicat softening point of 100 ° C. as a base resin was wound into a roll to obtain PS.
P is sequentially fed out, and the diameter is 400 according to the method shown in FIG.
While the PSP is in contact with the mm heating roll 2,
The PSP was pressed by the pinching roll 3 (without a temperature adjusting mechanism) at a substantially intermediate point of the portion where the SP was in contact with the heating roll 2. The processing conditions are as follows.

Central temperature of the heating roll surface: 143 ° C. End temperature of the heating roll surface: 139 ° C. Peripheral surface velocity of the heating roll: 34.4 m / min. Contact length of the PSP with the heating roll: 384 mm, contact time of the PSP with the heating roll: 0.67 seconds, PSP clamping pressure: 5.3 kg / cm

The distance between the heating roll 2 and the pinching roll 3 is 1.3 mm when the PSP is not passing,
It was set to 1.8 mm when P was passing. The thickness of PSP after the above heating and pressurization is 2.3.
It was ~ 2.4 mm.

Next, the surface of the PSP not subjected to the heat treatment and a stretched HIPS film having a thickness of 35 μ (trade name “Styrophan HS manufactured by Oishi Sangyo Co., Ltd.
R "), molten HIPS is extruded from the extruder (adjusted to have a thickness after lamination of 105 μ), and then the PSP and the stretched HIPS film are pressed with a pressing roll. Laminated under pressure. In the obtained laminated foam sheet, the total thickness of the stretched HIPS film and the layer of HIPS used as an adhesive (the thickness of the entire HIPS sheet) was 140 μm.

The heat shrinkage of the obtained laminated foam sheet in the PSP extrusion direction and the width direction, and HI from the laminated foam sheet
Table 1 shows the heat shrinkage load of the HIPS sheet measured by peeling off the PS sheet.

[0043]

[Table 1]

From the roll body obtained by winding the laminated foamed sheet obtained as described above, the laminated foamed sheet is sequentially fed out with the HIPS sheet side facing up, and the HI of the laminated foamed sheet is obtained.
Continuous thermoforming of the container was performed so that the PS sheet surface side was located on the outer surface side of the container. The laminated foam sheet is heated for 12 seconds until the surface temperature of the laminated foam sheet reaches about 120 ° C. by a heater (distance between heaters: 300 mm) provided above and below the laminated sheet in the heating zone of the molding machine. And then molded. Table 1 also shows the drawdown amount generated in the laminated foam sheet when the laminated foam sheet was heated in the heating zone, and the surface condition inside the container after heat molding. The number of containers taken per shot in this molding was 6 in the length direction and 6 in the width direction of the laminated foam sheet. The container obtained by molding has an inner diameter of the opening of about 14.2 cm (the outer diameter including the lip is about 15 cm) and an inner diameter of the bottom of the container is about 9.2 cm (the outer diameter is about 9.8c).
m) is a container having a circular cross section. The center line average roughness (JIS B0) on the outer surface side (HIPS sheet side) of the obtained container
601) was measured by a surface roughness measuring device “Surfcoder SE-30D” manufactured by Kosaka Laboratory Ltd. The measurement point was measured at a vertical position on the outer surface of the side wall of the container at a distance of 8 mm up and down. The values measured for each one spot of 36 containers for one shot were averaged, and this value is also shown in Table 1.

* 1: The initial load value was shown because it was below the initial load value when heated. * 2: When the laminated foam sheet is placed in the middle position between the upper and lower heaters and heated to cause drawdown in the laminated foam sheet, the original position of the laminated foam sheet and the bottom surface of the sheet hanging down due to the drawdown It is indicated by the distance to the department.

Comparative Example 1 A PSP similar to that of Example 1 was heat treated in the same manner,
Molten HIPS is extruded from the extruder on the surface of the PSP that has not been subjected to heat treatment, and the thickness of 140 is applied to the surface of the PSP.
A μ HIPS sheet was laminated. Table 1 shows the properties of the laminated foam sheet, the drawdown amount of the sheet in the heating zone when the laminated foam sheet was thermoformed in the same manner as in Example 1, and the surface condition of the laminated foam sheet after heating. Showed. The center line average roughness of the obtained outer surface of the container was measured in the same manner as in Example 1, and the results are also shown in Table 1. In addition, since there is a keloid-shaped sore in a part of the sheet surface due to drawdown during heating of the laminated foam sheet of Comparative Example 1, the average roughness of the outer surface of the container obtained from this laminated foam sheet was keloid-like. The measurement was performed while avoiding the sore part.

[0047]

Industrial Applicability As described above, the laminated foam sheet of the present invention, like the conventional styrene resin laminated foam sheet obtained by laminating the HIPS sheet on the PSP, can store the molding sheet for a long time before molding, It is possible to prevent the occurrence of drawdown due to heating during thermoforming without causing a problem such as deterioration of physical properties of the sheet. Since the laminated foam sheet of the present invention can effectively reduce or prevent the occurrence of drawdown even if the width of the laminated foam sheet is as large as about 1 m, the productivity of thermoformed products can be improved. It also contributes to. Since the laminated foamed sheet of the present invention is unlikely to cause drawdown, uneven heating during thermoforming is unlikely to occur, and as a result, a thermoformed product having excellent physical properties, appearance, etc. can be obtained. The larger the drawdown due to heating during thermoforming,
Since the surface area of the PSP becomes large and the air bubbles on the surface of the PSP expand and become large, the PS of the thermoformed product
Not only the surface on the P side, but also the surface on the HIPS sheet side is reduced in smoothness. Generally, when the smoothness of the surface is lowered, the printability (particularly curved surface printability) is deteriorated.
The laminated foam sheet of the present invention is effectively improved in drawdown and prevented from deteriorating the surface smoothness thereof, and thus is excellent in printability of a thermoformed product. Especially HIP
The heat shrinkage load of the S sheet is 11 g / 5 mm width to 20 g / 5 m at least in the longitudinal direction of the HIPS sheet.
When the width is m, the drawdown can be more effectively prevented. Even when using a thermoforming machine with a narrow heating heater interval, it is extremely unlikely that the sheet will come into contact with the heater or hang down near the heater.Therefore, the sheet will discolor or burn out like a keloid. There is no fear of a decline.

Further, the molten HIPS is extruded between the PSP and the stretched HIPS film so that the two are laminated and integrated, whereby the HIPS sheet of the laminated foamed sheet is formed into a stretched HIPS film and an unstretched HIPS film. When the HIPS sheet is composed of a layer and the unstretched HIPS layer is located on the PSP side, even if the thickness of the HIPS sheet is increased to some extent for the purpose of improving the impact resistance and strength of the molded product,
The adhesive strength between the PSP and the HIPS sheet does not decrease, and it is possible to manufacture at low cost even when the HIPS sheet has the same thickness as compared with the case where a single HIPS sheet stretched on the PSP is thermally laminated. Become.

Further, the laminated foamed sheet of the present invention has effects such that an excellent thermoformed product can be obtained by using a conventionally used general-purpose thermoforming machine as it is.

[Brief description of the drawings]

FIG. 1 is a process schematic view showing an example of manufacturing a laminated foam sheet of the present invention.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B32B 27/30 B32B 27/30 B B65D 1/09 B65D 1/00 B // B29K 25:00 105: 04 B29L 9:00 22:00

Claims (3)

[Claims] 1. A laminated foam sheet of a styrene resin foam sheet and a high impact polystyrene resin sheet, wherein the maximum value of the heat shrinkage load of the high impact polystyrene resin sheet is at least in the longitudinal direction of the high impact polystyrene resin sheet. The heat shrinkage of the laminated foam sheet having a width of 10 g / 5 mm or more and heating at 145 ° C. for 40 seconds is 0 to 25% in both the extrusion direction and the width direction of the styrene resin foam sheet. A styrene resin laminated foam sheet for thermoforming. 2. The maximum value of the heat shrinkage load of the high-impact polystyrene resin sheet is 11 g / at least in the longitudinal direction of the high-impact polystyrene resin sheet.
The styrene-based resin laminated foam sheet for thermoforming according to claim 1, which has a width of 5 mm to 20 g / 5 mm. 3. The high-impact polystyrene resin sheet is a laminated sheet of a non-stretched high-impact polystyrene resin layer and a stretched high-impact polystyrene resin film, and the non-stretched high-impact polystyrene resin layer side is a styrene resin. The styrene resin laminated foam sheet for thermoforming according to claim 1 or 2, which is laminated on the foam sheet side.