JPH037332A - Heat shrinkable foamable polystyrene composite sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a foamed polystyrene composite sheet having heat shrinkability.

[Prior Art] Heat-shrinkable expanded polystyrene sheets are widely used as covering labels for one-way bottles and plastic containers. When applied to such various fields, sheets are used after being printed. Since expanded polystyrene sheets are inherently opaque, these printings have no choice but to be applied to the surface of the sort. For this reason, during the process of attaching a printed label to a container, etc., or filling a container covered with a label with contents, the printed surface is rubbed, causing problems such as the printed pattern rubbing off and ink transfer. This is a problem that should be improved.

On the other hand, as a countermeasure to this problem, a composite sheet is created by laminating a foamed polystyrene sheet with a polystyrene film.
A method of printing between the two has been proposed. These methods include heating the polystyrene film and directly welding it to the foamed polystyrene sheet, or using an adhesive thermoplastic resin as a binder to bond the polystyrene film and the foamed polystyrene sheet together. ing.

However, when the composite sheet obtained by the above method is laminated with the polystyrene-based sort and the polystyrene-based film, which have heat-shrinkable properties, heat is applied and the foamed polystyrene-based sheet and polystyrene-based film shrink, resulting in the pattern being distorted. It is unstable because it is distorted or does not meet the specified dimensions.

Furthermore, since the foamed polystyrene sort adheres and the bubbles at the boundary surface expand during thermal bonding, the inherent surface smoothness of the polystyrene film is impaired, resulting in a significant reduction in commercial value. Moreover, sheets with impaired surface smoothness and large irregularities on the outer surface cause a lot of loss during the process of wrapping around containers. The process of wrapping such a sheet around a container is, for example, in order to cover the container with a sheet at a rate of 100 pieces/min or more, a long sheet is cut to a predetermined length and wrapped around the container just before being wrapped. Cover it, but
At this time, since one end of the sheet is suctioned and the rear end is cut with a cutter, if the sheet has an uneven surface, sufficient suction is not achieved and the cut surface lacks stability.

In addition, in order to reduce the heat required for adhesion, it is being considered to apply an adhesive based on thermoplastic resin that can be bonded at low temperatures during printing, but labels made of this composite sheet cannot be processed by heat treatment such as the BASTRO process. During the process, the foam sheet and film peel off at the interface, which limits its use.

[Problem to be solved by the invention]

The object of the present invention is to provide a composite sheet made by laminating a heat-shrinkable foamed polystyrene sheet and a polystyrene-based film, which has excellent dimensional stability of the design, and which does not cause wrinkles when heat-shrinked. It is an object of the present invention to provide a composite sheet with excellent appearance that can withstand such heat treatment steps.

[Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive research to solve the above problems.

That is, the present invention relates to a heat-shrinkable foamed composite sheet in which a heat-shrinkable foamed polystyrene sheet and a printed polystyrene-based film are bonded together, in which a polyurethane adhesive is used at the bonding interface. It is a polystyrene composite sheet.

The present invention will be explained in detail below.

In the present invention, what is heat-shrinkable expanded polystyrene notebook?
Thickness: 0.1~1. omm, preferably 0.15-0.
There are 5 pieces, and the apparent density is 0.15 to 0.70 g/c.
i, preferably 0.20 to 0.50 g/cm. Furthermore, when heated to 120°C, foamed notebooks tend to shrink significantly in the direction of flow, so preferably 30°C in one direction.
% or more, and has the property of shrinking by less than 20% in the direction perpendicular to the shrinkage. Preferably, the shrinkage is 40 to 70% in one direction and less than 15% in the direction perpendicular to the shrinkage. If the thickness of the foam sheet is less than 0.1 mm,
It is easy to tear during the laminating process (also, when making a sleeve with composite sheets, the strength of the sealing surface is insufficient,
Appearance defects occur. If the thickness exceeds 1 mm, folds and wrinkles will easily occur when making the sleeve. Further, if the apparent density of the foam sheet is less than 0.15 g/cm3, the composite sheet tends to shrink irregularly when heated. On the other hand, 0.
If it exceeds 7 g/Ci, the sleeve will easily crack and break when bent when making the sleeve. In addition, when a composite sheet laminated with a polystyrene film is attached to a container, etc., it is cut into a rectangular shape in the direction of high shrinkage or in the circumferential direction, and the end surface is knurled to form a cylindrical body (sleeve). ) is attached to the container and heated to make it stick. but,
The shrinkage performance of expanded polystyrene sheets in the circumferential direction is 30
If it is less than that, it becomes difficult for the cylindrical body of the composite sort to stick closely to the container. On the other hand, expanded polystyrene notebooks that have a shrinkage performance exceeding 2006 mm in the height direction will suffer from significant deformation of the design or shift of the mounting position after shrinkage, resulting in loss of commercial value.

In addition, the polyurethane adhesive coated surface of the foam sheet is
It is more preferable to perform a corona treatment, and in this case, the surface tension is preferably set to 36 dynes or more.

A method for producing a heat-shrinkable foamed polystyrene sheet will be described below.

Examples of raw material resins for such expanded polystyrene sheets include general purpose polystyrene (GPPS), high-impact polystyrene (DIPS), and copolymers of styrene with methacrylic acid, maleic anhydride, etc. Combination etc. can be used. There is no problem in adding rubber or olefin resin to this for the purpose of adjusting the flexibility and heat shrinkability of the foam sheet.

In addition, as a foaming agent for obtaining a foamed sheet, for example,
Hydrocarbon compounds such as butane, pentane, propane, and fluorocarbons such as 23, -134, -1 old, -22, -11, and
There are low-boiling point organic compounds such as halogen compounds such as No. 2, and thermally decomposable chemical blowing agents such as baking soda and citric acid. Nucleating agents such as talc and warp are used to adjust the size of bubbles. Further, additives such as antistatic agents and colorants may be added without any problem.

Foamed sort can be manufactured using ordinary foamed sheet extrusion equipment, and the thickness of the foamed sort can be adjusted by changing the take-up speed and the amount of resin discharged from a die attached to the tip of the extruder.

The apparent density of the foam sheet is controlled by the addition of a blowing agent, typically 5X1 when a low-boiling organic compound is used alone.
It is controlled at a value selected from the range of 0-' to 5XlO-' mol/100g, and when used in combination with a chemical blowing agent, the value becomes smaller than the above range.

The shrinkage performance of a foamed polystyrene sheet is imparted in the step of heating and mixing the raw materials in an extruder, releasing the mixture into the atmosphere, and taking the sheet.

On the other hand, the shrinkage rate in the direction of large shrinkage of the foam sheet is controlled, for example, by setting the take-up speed higher than the discharge speed from the resin die, and in that case, the take-up speed is usually 1.5 to 5 It is twice the size.

In addition, the shrinkage rate in the direction perpendicular to this is controlled by the ratio of the diameter of the die to the diameter of the expanded foam sheet (B, U, R,), and usually B, [1, R, is 1.5 to 2.5. The range is selected.

In addition, in expanded polystyrene sorting, GP is applied to one side.
PS, HrPS, styrene-butadiene block copolymer, styrene-ethylene-butylene block copolymer, styrene-butadiene rubber, etc. are mixed or used alone and are polystyrene resins with a range of 0005 to 0.0.
A coextruded foam sheet with a two-layer structure having a 5 mm non-foamed layer is suitable for increasing the adhesive force with the polystyrene film by arranging the non-foamed layer on the adhesive surface.

Polystyrene film has a thickness of 0.01 to 0, I
mm, preferably 0.015-0. O5ff1m, GPPS, IrPS, styrene-butadiene block copolymer, etc. are mixed or used alone, and the film is stretched in one direction or two directions. Preferably, the polystyrene film has heat shrinkage performance similar to that of the expanded polystyrene sheet.
Heat shrinkage performance is 25% or more in one direction (flow direction) when heated to 120"C, and 5 to 25% in the perpendicular direction.
%.

If the thickness of the film is less than 0.01 m, it will be easy to cut during the printing or laminating process, and
．． If it exceeds 1ml11, voids are likely to occur at the boundary with the foam sheet after lamination.

If the shrinkage rate (in the machine direction) when heated to 120°C is less than 25%, the composite sheet will become wrinkled due to insufficient shrinkage, which will not only spoil its appearance, but also cause it to be rolled loosely and not function as a label. do not have. In addition, if the shrinkage rate in the perpendicular direction is less than 594, it is easy to tear (increase loss) during the film forming, printing, or laminating process.On the other hand, if it exceeds 2593, the position of the label covering the container may be irregular. or the pattern becomes distorted.

In addition, in relation to the heat shrinkage performance of the foam sheet, the heat shrinkage performance of the polystyrene film is 1.0<foam sheet Shrinkage rate/Shrinkage rate of film <1.5.

If the shrinkage rate of the film is greater than that of the foam sheet, after it is made into a composite sheet, it is cut into rectangles, both ends are overlapped and sealed, and when it is attached to a container and heated, streak-like shrinkage wrinkles may occur. Occur. Conversely, if it exceeds 1.5, small wrinkles will appear on the film.

Further, when compared in the direction of small shrinkage, 0.6<shrinkage rate of foamed sheet I/shrinkage rate of film<2.0.

If the shrinkage rate of the film or the shrinkage rate of the foam sheet is less than 4, when heated, it may get caught in the upper and lower ends of the cylindrical body (sleeve) or on the foam sorting side, or the appearance may be damaged due to poor height etc. . On the other hand, if it is less than 0.6, both the upper and lower ends will be separated from the side wall of the container, curl up, and the appearance will be poor, causing the label to tear when the container is washed with water.

Next, a method for manufacturing the polystyrene film used in the present invention will be described.

The raw material resin used is GPPS, 1 (IPS), a copolymer of styrene-butadiene copolymer, methacrylic acid, maleic anhydride, etc., and styrene. There is no problem in adding rubber, elastomer, plasticizer, etc., or adding anti-banding agent, lubricant, etc.

The raw material resin for the film is preferably a mixture of styrene-butadiene copolymer and old PS or GPPS.

Although ordinary extrusion equipment can be used for the polystyrene film, an inflation method is preferable in order to impart the above-mentioned heat shrinkability. The thickness and heat shrinkage performance of the film can be controlled in the same way as for foam sheets.

The adhesive used in the present invention is a polyurethane adhesive, which can withstand heat treatment processes such as the BASTRO process, and does not harden the coated surface of the foam sheet or polystyrene film. It has the advantage of absorbing distortion when shaped into a shape.

The polyurethane adhesive referred to in the present invention is an adhesive made by reacting a normal polyisocyanate having two or more isocyanate groups per molecule with a polyether or polyester having hydroxyl groups at both ends, and is preferably an adhesive. It is a solvent-free type.

Specifically, hexamethylene isocyanate, lysine diisocyanate, 4.4-methylenebis(cyclohexyl isocyanate), methylenecyclohexane 2.4(
2,6>diisocyanate, 1,3-(isonoanatomethyl>enclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid isocyanate, tolylene diisocyanate,
Obtained by reacting a compound containing two or more isocyanate groups per molecule such as 4,4'-diphenylmethane diisocyanate, quinollylene diisocyanate, metaxylylene diisocyanate, etc. with a polyester, polyether, glycol, etc. having a hydroxyl group at the end. It is an adhesive. Preferably, it is a two-component adhesive obtained by reacting a water-adducted polyisocyanate of hexamethylene incanate with a polyester having hydroxyl groups at both ends, such as the trademark Atcoat AD-N401 A/B.
(manufactured by Toyo Morton Co., Ltd.), trademark Orester NP-1100
/NL-2448 (manufactured by Mitsui Toatsu Chemical Co., Ltd.).

In order to apply the polyurethane adhesive to the interface between the heat-shrinkable polystyrene foam sheet and the polystyrene film, a normal dry lamination device can be used, and the amount of polyurethane adhesive applied is approximately lJim- in thickness. 1
It is in the range of 0 μm.

If the thickness is less than 1 μm, the adhesive force between the expanded polystyrene sheet and the polystyrene film is insufficient, and when heat treatment such as the PASTRO process is performed, the film partially lifts. Further, even if the length is 108 m or more, it cannot be expected that the dimensional stability of the design, which is an effect of the present invention, will be further improved.

The heat-shrinkable foamed polystyrene composite sheet of the present invention is constructed by bonding the above foamed polystyrene sheet and polystyrene film together using a polyurethane adhesive.

In this composite sheet, characters and designs are printed on the surface of the polystyrene foam notebook or on the back of the polystyrene film, preferably on the back of the polystyrene film, and the characters and designs are printed on the polystyrene foam sheet and the polystyrene film. The sheet and film are adhered with a polyurethane adhesive so as to be sandwiched between them.

Specific aspects of the composite sheet include, for example, a form in which a polyurethane adhesive is applied to the surface of a foamed polystyrene sheet with letters or designs printed on the surface, and a polystyrene film is laminated thereon; Examples include a method in which a polyurethane adhesive is applied to the surface of the sheet, and a polystyrene film with letters, designs, etc. printed on the back is laminated thereon. Preferably, the back side of the polystyrene film is printed, a polyurethane adhesive is applied thereon, and then the expanded polystyrene notebook is pasted. Further, in these embodiments, in order to produce a unique pattern effect, it is acceptable to print on both the back side of the film and the front side of the sort, as long as these printed sides are on the bonded side of the composite sheet.

[Action and effect]

The heat-shrinkable foamed polystyrene composite sheet of the present invention does not directly rub against printing ink, and prevents ink from dripping.
Problems such as ink transfer are resolved, and since it is possible to bond at a temperature that does not cause thermal contraction or bubble expansion, there is almost no change in the printed design, and the product value is increased without compromising surface smoothness. It is possible to increase

In addition, the composite sheet of the present invention has the rigidity and surface smoothness of foamed polystyrene sheets, so in the case of devices that are attached to containers at high speed, losses such as misalignment and bending of the sheet can be greatly reduced. It is possible to reduce the

In addition, when a cylindrical body is made from the composite sheet of the present invention and then inserted into a container and heat-shrinked, a heat-shrinkable label with an excellent appearance without wrinkles or curling due to poor shrinkage can be obtained.

Furthermore, labels coated on containers may develop delamination, etc., even on lines that require heat treatment such as the PASTRO process.
It has a wide range of applications.

〔Example〕

Next, the present invention will be explained using representative examples.

Example 1 Heat-shrinkable polystyrene foam 1/GPPS (Tobolex; manufactured by Mitsui Toatsu Chemical Co., Ltd.) 100
Talc (Micro Ace, manufactured by Nippon Talc) 0.3 in weight part
parts by weight and 5 parts by weight of Freon 22 (manufactured by Mitsui, DuPont Fluor Chemical) were used as raw materials for the foam layer, while 100 parts by weight of GPPS (Topolex), 10 parts by weight of a styrene-ethylene-butylene block copolymer, and 3 parts by weight of a white colorant.
This is a heat-shrinkable foam notebook with a two-layer structure obtained by a coextrusion method using part by weight as the raw material for the non-foamed layer, and the foam sheet has a thickness of 0.17 mm for the foam layer and 0.1 mm for the non-foamed layer. 015mm, and the shrinkage rate when heated to 120℃ is 55mm in the machine direction.
%, and the sheet that is j5% perpendicular to it.

Polystyrene film Styrene-butadiene block copolymer (K-resin: manufactured by Philips) 20 parts by weight and 80 parts by weight of GPPS (Tobolex) were mixed into B and U using a 40 mmΦ extruder.
, R, or 2.3. When heated to +20°C, the film shrinks by 40% in the machine direction and 12% in the direction perpendicular to it, and has a thickness of 0.
Films in 025 order.

The film was printed so that characters and designs could be read through the film.

The heat-shrinkable expanded polystyrene sort and polystyrene film were bonded together using a solvent-free two-component polyurethane adhesive (Atcord: manufactured by Toyo Morton Co., Ltd.).
The dimensions of the obtained composite sort were not only stable and accurate within 0.2 m+++ in both the flow direction and the direction perpendicular thereto, but also smooth without impairing the surface properties of the polystyrene film.

Smoothness test method using Beck tester (J I 5
P-8119), it was 900 seconds or more.

In addition, this composite sheet was slit into a ring shape with a width of 100 mm and tested using a wrapping production machine in order to wrap it around a glass bottle. The labels were cut stably, had high dimensional accuracy, and had little loss.

When the lath pin with the label wrapped around it was passed through a shrink tunnel at 170°C, it shrunk until it came into close contact with the shoulder and bottom of the bottle.

Comparative Example 1 A composite notebook was obtained using the same materials as in Example 1, except that instead of the polyurethane adhesive of Example 1, a polystyrene film was thermally welded to a heat-shrinkable expanded polystyrene sheet using a heating roll.

The main physical properties and evaluation results are shown in Table-1.

Comparative Example 2 Shrinkage rate of expanded polystyrene sheet is 25% in one direction
, Example 1 except that it has a performance of 5% in the direction perpendicular to it.
A composite sheet was obtained in the same manner as above. Even when the obtained sheet was wrapped around a bottle and passed through a shrink tunnel, it did not shrink sufficiently and uneven shrinkage occurred.

Examples 2 to 5, Comparative Examples 3 to 8 Foamed sheets having different thicknesses, apparent densities, and shrinkage rates were manufactured according to the following manufacturing example of heat-shrinkable foamed polystyrene sheets.

Table 2 shows the properties of each foam sheet.

Example of manufacturing heat-shrinkable polystyrene foam sheet Using tandem foam extrusion equipment with a diameter of 50 to 65 mm, 100 parts by weight of GPPS (Tobolex: manufactured by Mitsui Toatsu Chemical Co., Ltd.) and 0.0 parts by weight of talc (Micro Ace: manufactured by Nippon Talc Co., Ltd.) were prepared. 3 parts by weight were melted and mixed, and Freon 22 (Mitsui, Table 1 Shrinkage rate measurement conditions; Immersed in an oil bath at 120'C for 1 minute for smoothness; Beck tester used, manufactured by DuPont Fukuro Chemical Co., Ltd.) was injected and kneaded. After that, it is released into the atmosphere from the die to form a foam layer.
On the other hand, 100 parts by weight of GPPS ()-Bolex), 10 parts by weight of a block copolymer of styrene, ethylene, and butylene, and 3 parts by weight of a white colorant were melt-kneaded and extruded using a 40 mm diameter extruder, and the non-foamed layer ( A foamed sheet having a two-layer structure having a non-foamed layer (weight ratio: 25%) was obtained by a coextrusion method.

B, U, and R were set to 2.3, and the thickness of the foam sheet was adjusted by changing the take-up speed, and the apparent density was determined by the amount of foaming agent injected.
In addition, the heat shrinkage performance can be improved by changing the opening area of the die.
Adjusted by changing the discharge speed.

The same polystyrene film and adhesive as in Example 1 were used, except that the foamed sheet shown in Table 2 was used, and the film was printed on a polystyrene film with a thickness of 2 μm using a normal dry laminating machine. After applying an adhesive and pasting them together so that they were printed or in the middle, they were cured in a constant temperature room for 48 hours to obtain a composite sheet.

Table 2 shows that the shrinkage of the pattern printed on the composite sheet made by laminating a heat-shrinkable polystyrene foam sheet and a polystyrene film was stable within 0 and +06 in both the machine direction and the width direction.

The composite sheet was further subjected to practical evaluation for each process using the following evaluation methods.

Performance evaluation of composite sheet; (1) Sleeve creation and installation process;
After cutting to the size of X95 drawing and heat rolling to continuously create a sleeve, the body diameter is 52 positive φ and the height is 1
Attach to a 25-neck glass bottle.

(2) Heat shrinkage step: The sample is passed through a shrink tunnel at an ambient temperature of 170° C. and brought into close contact with a glass bottle to judge its appearance.

(3) Filling process: A glass bottle covered with a composite sheet label is filled with a beverage that has passed through the Pastro (80°C) process, and when it comes out, the appearance of the label is judged.

The evaluation results of the composite sheet are also shown in Table-2.

It can be seen that the performance of the composite notebook changes significantly depending on the thickness of the foam sheet, the apparent density of the foam sheet, and the heat shrinkage rate of the foam sheet.

Examples 6 to 7, Comparative Examples 9 to 12 In the method for producing heat-shrinkable polystyrene foam notebook of Example 2, a single-layer structure consisting of only the foam layer excluding the non-foam layer was used, and the thickness was 0.17 am and the apparent is the density 0゜35g/cd
A foamed notebook with a shrinkage rate at +20° C. of 56% in the machine direction and 14% in the width direction was obtained. A composite sheet was obtained using the same adhesive used in Example 2, except that the thickness and heat shrinkage rate of the polystyrene film were changed. The physical properties of these composite sorts were evaluated for each step in the same manner as in Example 2.

The results are shown in Table-3.

It can be seen that the performance of the composite sheet changes significantly depending on the film thickness and heat shrinkage rate.

Example 8, Comparative Examples 13 to 14 Composite sheets were obtained in the same manner as in Example 1 except that the adhesive was changed. Table 4 shows the physical properties and evaluation results of the composite sheet.
It was shown to.

In Example 8, a polyurethane adhesive (manufactured by Mitsui Toatsu Chemical Co., Ltd., trademark Ole) obtained by reacting polyisoneanate with a 1-group ratio of about 23% and a polyester having hydroxyl groups at both ends was used as an adhesive. Star NP-1100
) was used, and in Comparative Example 13, a solvent type adhesive (manufactured by Koniso Co., Ltd., trademark Konishi Bond VP2000) was used, and in Comparative Example 14
In each case, ethylene-vinyl acetate copolymer was used.

From Table 4, Example 8 is superior to Comparative Examples 13 and 14 in terms of pattern changes and subsequent steps.

Comparative Example 15 A composite sheet was obtained using the same materials as in Example 1, except that instead of the polyurethane adhesive in Example 1, a polystyrene film was thermally welded to a heat-shrinkable expanded polystyrene sheet using a heating roll. .

The surface temperature of the heating roll was set to +60°C, and the adhesive strength between the foamed polystyrene sheet and the polystyrene film was sufficient, but there was a lot of shrinkage loss in the design range of 2 to 5%.

Also, a sleeve was made from this composite sheet. Table-4 After coating the bottle, After going through the BASTRO process The film peeled off partially.

Claims (1)

[Scope of Claims] 1) A heat-shrinkable foamed polystyrene composite sheet made by laminating a heat-shrinkable foamed polystyrene sheet and a polystyrene film together using a polyurethane adhesive. 2) A heat-shrinkable polystyrene foam sheet that is made by laminating a heat-shrinkable polystyrene foam sheet and a polystyrene film together using a polyurethane adhesive, and the bonded surface of the sheet and/or film is printed. composite sheet. 3) The thickness of the heat-shrinkable polystyrene foam sheet is 0.
10 to 1.0 mm, and the apparent density is 0.15 to 0.
．． The heat-shrinkable foamed polystyrene composite sheet according to claim 1 or 2, which has a weight of 70 g/cm^3. 4) The heat shrinkage according to claims 1 and 2, wherein the heat shrinkage performance of the heat shrinkable polystyrene foam sheet is such that when heated to 120°C, the heat shrinkage performance is 30% or more in one direction and less than 20% in a direction perpendicular to the heat shrinkage performance. Polystyrene foam composite sheet. 5) The heat-shrinkable foamed polystyrene composite sheet according to claim 1 or 2, wherein the polyurethane adhesive is a solvent-free type. 6) The heat-shrinkable foamed polystyrene composite sheet according to claim 1 or 2, wherein a polyurethane adhesive is applied to a thickness of 1 to 10 μm. 7) Thickness of heat-shrinkable polystyrene foam sheet is 0.1
0-1.0mm, apparent density 0.15-0.7
0g/cm^3 sheet and a printed polystyrene film with a thickness of 0.01 to 0.1mm are bonded together using a polyurethane adhesive coated with a thickness of 1μm or more. The heat-shrinkable expanded polystyrene composite sheet according to claim 2. 8) The heat shrinkage performance of the heat shrinkable polystyrene foam sheet is such that when heated to 120°C, it shrinks by 30% or more in one direction and less than 20% in the direction perpendicular to it, and the heat shrinkage performance of the polystyrene film is 100%. 8. The heat-shrinkable foamed polystyrene composite sheet according to claim 1, 2 or 7, wherein the heat-shrinkable expanded polystyrene composite sheet is 25% or more in one direction and 5 to 25% in a direction perpendicular thereto when heated to a temperature of .degree. 9) The heat shrinkage performance of the polystyrene film is 12 in the same direction when laminated with the heat shrinkable polystyrene foam sheet.
The shrinkage rate at 0°C is 1.0 in the direction where the foam sheet shrinks the most.
<Shrinkage rate of foam sheet/Shrinkage rate of film<1.5, and in the direction of smaller shrinkage of the foam sheet, 0.6<Shrinkage rate of foam sheet/Shrinkage rate of film<2.0.Claims 1 and 2
or the heat-shrinkable foamed polystyrene composite sheet according to 7.