JPH04166331A - Foamed sheet and its manufacture - 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 foam sheet and a method for manufacturing the same. More specifically, the present invention relates to a foamed sheet with excellent heat insulation properties, cushioning properties, strength, thermoformability, adhesiveness, surface smoothness, etc., and a method for producing the same.

The foam sheet produced by the method of the present invention can be used for automobile interior parts, box-shaped insulation materials and cushioning materials for ice boxes, etc.
It can be suitably used for containers such as food containers.

[Prior Art] Foamed polyolefin resin sheets have been used in various fields, and the following methods (1) to (3) are known as methods for producing them.

(1) A composition obtained by adding a substance that thermally decomposes to generate gas, a so-called blowing agent, to a polyolefin resin is extruded using an extruder while melting and kneading at a temperature higher than the temperature at which the blowing agent decomposes. A method of producing a single layer foam sheet by.

However, method (1) above has a foaming ratio of 1 or about 1.
It is said that this method is suitable for producing products with a low foaming ratio of 5 times or less, or that the resulting low foaming ratio products do not sufficiently exhibit the effects of foaming such as insulation, cushioning, and lightness. There are some drawbacks.

In addition, when manufacturing a product with a high expansion ratio, there is a drawback that as the expansion ratio increases, the surface of the foam sheet becomes extremely rough and is of no practical value.

(2) A method of manufacturing a single-layer foam sheet by melt-kneading and extruding a polyolefin resin while injecting gas or a highly volatile liquid from a part of the cylinder of an extruder.

However, method (2) above can produce both low expansion ratio products and high expansion ratio products. Since it is hydrogen, it causes environmental pollution and destruction, which is a big problem in terms of environmental conservation.

(3) A blowing agent and a crosslinking aid such as divinylbenzene are blended into a polyolefin resin, the resulting composition is molded into a sheet at a temperature that does not decompose the blowing agent, and the sheet is then irradiated with an electron beam, etc. A method of producing a single-layer foamed sheet by causing a crosslinking reaction and crosslinking, and then heating the sheet to a temperature higher than the temperature at which the foaming agent decomposes to cause foaming.

However, even in the method (3) above, it is not possible to manufacture both low expansion ratio products and high expansion ratio products, the manufacturing process is complicated, and there are many restrictions on the raw materials that can be used. Since delicate control of the crosslinking reaction and subsequent foaming process is difficult, there are problems with product quality stability, and the product is also very expensive.

In addition, since the polyolefin resin foam sheets obtained by methods (1) to (3) above are all made of a single layer of polyolefin resin, their adhesive properties are not sufficient.
Furthermore, since the foam sheet does not have a high-strength unfoamed layer, it has the disadvantage that when a strong compressive force is applied from the outside, the bubbles collapse and gas easily escapes.

[Problems to be solved by the invention] Polyolefin resin foam sheets are extremely useful industrially. (2) The materials used in the production cause environmental pollution or destruction; (3) The quality of the product is not stable enough and it is expensive; (4) Compression There are problems such as weak strength and (5) insufficient adhesion.

The present invention has been made based on the above circumstances.

The purpose of the present invention is to improve the problems (1) to (5) above, have no unevenness on the surface, have excellent adhesiveness and printability, have a foaming ratio of approximately 2 to 25 times, and a thickness of approximately 1 to 51 times. - To provide a foamed sheet of polyolefin resin and a method for easily producing the same.

[Means for solving the problem] The structure of the invention of claim 1 for achieving the above object is as follows:
On both sides of the polyolefin resin composition containing a polyolefin resin and a blowing agent, a polyolefin resin of 80~
30% by weight of a polyamide resin blended composition containing 20 to 70% by weight of a polyamide resin having a melting point 75°C or higher than the melting point of the same or similar polyolefin resin to the polyolefin resin. The structure of the invention according to claim 2 is a foamed sheet consisting of a polyolefin resin set containing a polyolefin resin and a blowing agent having a decomposition temperature 30 to 75 degrees Celsius higher than the melting point of the polyolefin resin, The polyolefin resin composition is formed into a sheet by molding at a temperature below the decomposition temperature of the blowing agent, and 80 to 30% by weight of a polyolefin resin that is the same as or similar to the polyolefin resin is applied to both sides of the sheet made of the polyolefin resin composition obtained. and 20 to 70% by weight of a polyamide resin having a melting point higher than the melting point of the same or similar polyolefin resin as the polyolefin resin, and the resulting laminated layer. The sheet is heated at a temperature higher than the decomposition temperature of the foaming agent and lower than the melting point of the polyamide resin to foam the sheet layer made of the polyolefin resin composition, and the resulting heated foamed sheet is cooled without being pressed from both sides. This is a method for manufacturing a foam sheet, characterized by:

The present invention will be explained in more detail below.

In the present invention, a polyolefin resin composition (A) is prepared by blending a polyolefin resin and a blowing agent.

Specific examples of the polyolefin resin suitable for the present invention include crystalline polypropylene homopolymers, copolymers of crystalline propylene and comonomers other than propylene, low density polyethylene, medium density polyethylene, and high density polyethylene.

Linear low density polyethylene, ultra low density polyethylene,
Examples include ethylene vinyl acetate copolymers.

As the polyolefin resin, two or more of the various resins mentioned above may be used as a mixture.

The melting index of the polyolefin resin is preferably 0.5 to 5 g/10 min, whether there is any particular limitation or considering the extrusion processing method described below and the uniformity of foaming during foaming.

In addition, the melting index in the present invention is measured by the JIS method, and for example, for polyethylene, the melting index is measured by the JIS method.
The values measured at 11750 and K6758 for polypropylene are used as the respective melting indexes.

The blowing agent in the present invention may be one whose decomposition temperature is 30 to 75°C higher than the melting point of the polyolefin resin specifically used.

When the temperature is lower than the decomposition temperature of the blowing agent or a temperature 30° C. higher than the melting point of the polyolefin resin used, in the step of producing a sheet made of the polyolefin resin composition (A).

The foaming agent may partially foam due to shear heat generation or the like.

In addition, if the decomposition temperature of the foaming agent is higher than the melting point of the polyolefin resin by more than 75°C, the laminated sheet must be heated at a higher temperature in the step of heating and foaming the laminated sheet described below. As a result, the melt viscosity of the laminated sheet decreases too much, and the transportability of the heat-foamed sheet, which will be described later, deteriorates, making transport difficult and making it impossible to obtain a foamed sheet with excellent product uniformity and appearance.

Note that the melting point in the present invention is determined by differential scanning calorimetry (DSC).
) is the value obtained from the melting peak determined by Depending on the resin, there may be more than one melting peak, and in this case, the melting point of the resin is the maximum peak.

Suitable blowing agents in the present invention include azo compounds such as azodicarbonamide, azobis-imbutyronitrile, barium azodicarboxylate, and azocyclohexyl nitrile.

Benzenesulfonyl hydrazide, P, P“-oxy-
Sulfonyl hydrazide compounds such as bis(benzenesulfonyl hydrazide), para-toluene sulfonyl azide, trihydrazinotriacine, dinitroso pentamethylene tetramine, N, N'-dinitroso-N,
Examples include nitroso-based compounds such as N'-dimethylterephthalamide, mixtures of carbonates and organic acids (Dyflo 1003, etc., manufactured by Dainichiseika Chemical Industry Co., Ltd.), and the like.

The above blowing agents may be used in combination of two or more.

The polyolefin resin composition (A) obtained as described above is formed into a sheet to produce a sheet made of the polyolefin resin composition (A).

Methods for forming the polyolefin resin composition (A) into a sheet include a calendar method, an extrusion molding method using a T-tie,
Although a known method such as a hot press method may be used as an example, an extrusion molding method using a T-die is particularly preferred in terms of workability, adjustability of thickness, etc.

The extrusion temperature may be higher than the melting point of the polyolefin resin and lower than the decomposition temperature of the blowing agent.

If the extrusion temperature is lower than the melting point of the polyolefin resin, the polyolefin resin composition (
A) cannot be extruded.

Furthermore, when the extrusion temperature is close to the melting point of the polyolefin resin, the melt viscosity is high, which increases shear heat generation, making it difficult to control the temperature during extrusion.

Therefore, it is preferable that the extrusion temperature is at least 10° C. higher than the melting point of the polyolefin resin.

Furthermore, when the extrusion temperature is higher than the decomposition temperature of the blowing agent, the blowing agent decomposes, so the polyamide resin composition (B) described below is replaced by the polyolefin resin composition (A). It becomes impossible to layer the sheets uniformly.

In the present invention, the polyamide resin composition (B) is laminated on both sides of the obtained sheet made of the polyolefin resin composition (A).

The polyamide resin blend composition (B) in the present invention
can be obtained by blending a polyolefin resin and a polyamide resin.

The polyolefin resin in the polyamide resin blended composition (B) is the same as or similar to the polyolefin resin used to form the polyolefin resin composition (A). It will be done.

The above-mentioned similar polyolefin resin refers to a group that is a further classification of polyolefin resins, for example, a classification system such as polypropylene type or polyethylene type.

Therefore, the polyolefin resin that is the same as the polyolefin resin or the polyolefin resin used each time is, for example, the polyolefin resin composition (
In the case of the polyolefin resin or polypropylene resin used in A), the polypropylene resin specifically used in the polyolefin resin composition (A) or a polypropylene resin other than the polypropylene resin specifically used. A resin selected from polypropylene resins.

The polyolefin resin used in the polyamide resin blended composition (B) is selected from polyolefin resins of a different type from the polyolefin resin used to form the polyolefin resin composition (A). In the case of using a resin made of polyolefin resin (for example, in the case of a combination of high-density polyethylene and polypropylene), the surface smoothness of the resulting foamed sheet will be poor, and the polyolefin resin composition (A) and the polyamide resin Adhesiveness to compounded composition (B) is significantly reduced.

Suitable examples of the polyolefin resin in the polyamide resin composition (B) include polyolefin resins, which are exemplified as suitable examples of the polyolefin resin in the polyolefin resin composition (A). .

The polyamide resin in the present invention has a melting point that is 75° C. or more higher than the melting point of the polyolefin resin in the polyamide resin blend composition (B).

If the melting point of the polyamide resin is less than 75°C higher than the melting point of the polyolefin resin, when heating the laminated sheet described below to foam the sheet made of the polyolefin resin composition (A), The melt viscosity of the laminated sheet layer is insufficient, making it impossible to confine the gas generated from the blowing agent in the sheet made of the polyolefin resin composition (A), and making it difficult to transport the heat-foamed sheet.

The preferred polyamide resin in the present invention includes:
(-Ring-opening polymer of caprolactam (nylon 6), polycondensation product of hexamethylenediamine/adipic acid (nylon 66), polycondensation product of hexamethylenediamine/sebacic acid (nylon 61O), polycondensation product of 11-aminoundecanoic acid (nylon 11), a ring-opening polymer of ω-laurolactam (nylon 12), and the like.

The amount of the polyamide resin in the polyamide resin composition (B) is 20 to 70% by weight.

Preferably it is 30 to 60% by weight.

If the blended amount of the polyamide resin is 20% by weight, in the step of foaming the sheet made of the polyolefin resin composition (A), the amount of the polyamide resin blended composition (B) is Due to the lack of melt viscosity, it becomes impossible to incorporate the generated gas into the sheet of the polyolefin resin composition (A), making it difficult to transport the heat-foamed sheet.

When the blending amount of the polyamide resin exceeds 70% by weight, the heat fusion properties between the layer made of the polyamide resin blended composition (B) and the sheet made of the polyolefin resin composition (A) may be affected. Because of this, peeling occurs, making it impossible to confine the gas generated from the foaming agent into the sheet of the polyolefin resin composition (A).

In the present invention, the polyolefin resin composition (
The polyamide resin blended composition (B) is laminated on both sides of the sheet made of A) and integrated to obtain a laminated sheet.

Examples of methods for producing the laminated sheet include known methods such as coextrusion, extrusion lamination, and producing an integrated sheet using an adhesive.

The above coextrusion method is a method of coextruding the polyolefin resin composition (A) and the polyamide resin composition (B).

The above-mentioned extrusion lamination method is a method in which the polyamide resin composition (B) is melt-kneaded in an extruder and then extruded from a T-die onto a sheet made of the polyolefin resin composition (A) for integration. It is.

The method of using the above adhesive is to form the polyolefin resin composition (A) and the polyamide resin composition (B) into a sheet in advance, and then integrate the sheets together using an adhesive. This is the way to do it.

Among the above methods, the coextrusion method and the extrusion lamination method are particularly preferred in terms of productivity, workability, etc.

The calendar made of the polyamide resin blended composition (B) is
It is preferable that both sides of the sheet made of the polyolefin resin composition (A) have approximately the same thickness, and it is particularly preferable that the thickness on one side is about 0.05 to 0.31.

In addition, when manufacturing a foam sheet with a low expansion ratio, the thickness of the calendar made of the polyamide resin blended composition (B) is made thin, and when manufacturing a foam sheet with a high expansion ratio, the thickness is increased. It is preferable to do so.

The reason why the thickness is adjusted in this way is that the amount of gas generated during foaming differs depending on the expansion ratio, and the higher the expansion ratio, the greater the pressure applied to the layer made of the polyamide resin blended composition (B). .

In the present invention, the sheet made of the polyolefin resin composition (A) is foamed by heating the obtained laminated sheet to obtain a heat-foamed sheet.

Methods for heating the laminated sheet include a method in which the laminated sheet is brought into contact with a heated roll, a method in which the sheet is heated in a heating oven, a method in which the sheet is brought into contact with a heating plate, a method in which the laminated sheet is immersed in a bathtub of heated liquid, and Examples include methods that combine methods.

The heating temperature of the laminated sheet is set to be higher than the decomposition temperature of the foaming agent and lower than the melting point of the polyamide resin.

When the laminated sheet is heated at a temperature higher than the decomposition temperature of the foaming agent, it takes a long time to sufficiently foam the sheet made of the polyolefin resin composite (A).

Therefore, in particular, about 10
It is preferable to heat the laminated sheet at a temperature higher than .degree. C. or higher.

Furthermore, if the heating temperature is higher than the melting point of the polyamide resin, it becomes impossible to confine the gas generated from the blowing agent into the sheet made of the polyolefin resin composition (A), and the heating It becomes difficult to transport the foam sheet, and even if the heated foam sheet is forcibly transferred to the cooling process, a good foam sheet cannot be obtained.

In the present invention, the foamed sheet of the present invention is obtained by cooling the heated foamed sheet while holding it down from both sides.

Examples of methods for cooling the heat-foamed sheet without pressing it from both sides include passing it between a pair of cooling rolls, passing it between a pair of cooled steel belts, and using a cooled press. Can you give an example?

In the method using the above-mentioned press machine, the heat-foamed sheet is placed on a stainless steel plate, the stainless steel plate is attached to the bolster of the press machine, and the heat-foamed sheet is pressed from both sides.

By the way, in the above press machine, is a stainless steel plate with a clearance adjustment device attached to the bolster on the side where the stainless steel is not attached so that the foam sheet can maintain a constant thickness? More preferred.

The pressure applied to the heat-foamed sheet may be adjusted appropriately to obtain the desired thickness, or in the case of using the above press machine, 0.5 to 5 kg/cm2.
Is it preferable?

If the heat-foamed sheet is cooled without being suppressed, the surface smoothness of the resulting foamed sheet will deteriorate, and the adhesiveness between the polyolefin resin composition (A) and the polyamide resin blended composition (B) will deteriorate. or decrease.

When using the above press machine, when pressing,
The heat-foamed sheet can be cooled by passing cooling water through the bolster of the press.

The cooling temperature of the heat-foamed sheet is preferably 40''C or less.

If the cooling temperature of the heat-foamed sheet is higher than 40° C., the cooling time may become longer or the product may become deformed.

The polyolefin resin composition (A) and the polyamide resin composition (B) used in the method for producing a foamed sheet of the present invention contain an antioxidant,
Dispersants, foaming aids, antistatic agents, ultraviolet absorbers, metal-resistant agents, S coloring agents, fillers such as calcium carbonate and talc,
Synthetic rubbers, various thermoplastic resins, thermoplastic resins modified with maleic anhydride and acrylic acid, and the like may be included as additional components.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The types and characteristics of the polyolefin resins, polyamide resins, and blowing agents used in Examples and Comparative Examples are shown in Table 1.

Regarding the melting point of each resin, the maximum peak of the melting points determined by a differential scanning calorimeter (DSC) was taken as the melting point.

The melting index of each resin is JIS for vopropylene.
6758, JIS 1 for polyethylene
7) I asked for K6760.

(Preparation of foam sheet) (1) II Calendar Receipt Creation As the polyolefin resin composition (A).

As shown in Table 2, a blowing agent is blended with polyolefin resin, and 0.3P of liquid paraffin is added as an adhesive.
After adding HR, the mixture was mixed for 3 minutes using a high-speed rotating mixer (Herschel mixer) before use.

The polyamide resin composition (B) was prepared by blending the resins shown in Table 82 and mixing them in a tumbler for 5 minutes.

The laminated sheet is made using cylinder diameters of 4511φ and 65mm.
A coextrusion sheet manufacturing apparatus equipped with two extruders of mmφ was used.

The optical device was also equipped with a three-layer multi-manifold type T-die with a width of 800 mmφ.

Polyolefin resin composition (
A) is coextruded with the polyamide resin blend composition (B) using a 4Sv++φ extruder to obtain polyamide resin blend composition (B)/polyolefin resin composition (A)/polyamide resin blend composition (B). The three-layer sheet was adjusted to have the thickness shown in Table 2 and extruded at the extrusion temperature shown in Table 2 to produce a laminated sheet.

(2) Heat foaming of the laminated sheet The laminated sheet obtained in (1) above was heated to 30 csx 30 c
It was cut to a size of m.

The cut laminated sheet was placed in a silicone oil bath heated with an electric heater and heated under the conditions of temperature and time shown in Table 2 to foam the laminated sheet.

One side of the heat-foamed laminated sheet was held between two sides using a take-out tool having three clamping parts, and the sheet was taken out from the silicone oil tank.

(3) Cooling of the heated foamed sheet The taken out heated foamed sheet was transferred onto a stainless steel plate with a thickness of 5 mm and a size of 40 csx 50 cm.

This was quickly transferred to a press machine together with a stainless steel plate, and cooled while being pressed from both sides of the heated foam sheet.

A stainless steel plate was also attached to the press machine on the bolster on the side opposite to the side with the stainless steel plate on which the heat-foamed sheet was placed.

A clearance adjustment device was attached to the stainless steel plate so that a constant thickness could be maintained even when the foam sheet was pressed.

Cooling water was passed through the press bolster to cool the heated foam sheet.

Cooling was carried out under the conditions shown in Table 2, and the pressing force of the press was 2 kg/cm2.

(Evaluation Criteria for Foamed Sheets) ■Condition of Laminated Sheet The relationship between the contents of the 0 judgment determined by visual inspection and the symbols in Table 2 is as follows.

◎ No foaming or very good surface smoothness 0 Slight foaming or good surface smoothness △ Noticeable foaming and considerable surface unevenness X Foaming or frequent occurrence or surface unevenness ■Transportability of heat-foamed laminated sheets The extent to which the heat-foamed sheets retain their original shape before being transported after being transferred to the cooling process is determined by visual inspection. The relationship is as follows.

◎ Original shape retention rate of 95% or more O Original shape retention rate of 80-94% △ Original shape retention rate of 50-79% × Original shape retention rate of 49% or less ■ Contents of 0 judgment visually judged for surface smoothness and symbols in Table 2 The relationship is as follows.

O Very good with almost no unevenness ○ Some unevenness or good △ Many unevenness or problems × Many unevenness ■ Relationship between adhesion evaluation contents of compositions (A) and (B) and symbols in Table 2 is as follows.

O Not peeled off, good 〇 Partially peeled off but no problem △ Easily peeled off A foamed sheet was produced and evaluated.

In Examples 1 to 3, polypropylene resins having different properties were used as the polyolefin resins, and foamed sheets were produced under the conditions shown in Table 2.

In Examples 4 and 5, foamed sheets were produced in the same manner as in Examples 2 and 3, except that polyethylene resin was used as the polyolefin resin.

In Examples 6 and 7, the amount of foaming agent blended in Example 2 was changed, and foamed sheets were produced under the cooling conditions shown in Table 2.

In Example 8, low density polyethylene with a low melting point was used as the polyolefin resin, and a foaming agent and polyamide resin compatible with this were used.

In Example 9, the same polyethylene resin as in Example 8 was used as the polyolefin resin, and a combination of two types was used as the blowing agent.

In Example 10, the polyolefin resin composition (
The same procedure as in Example 2 was conducted except that the polyolefin resin A) was a mixture of polypropylene and polyethylene.

In Example 11, a polyamide resin blended composition (
As the polyolefin resin B), a polypropylene different from or similar to the resin used in the polyolefin resin composition (A) was used.

Examples 12 and 13 were carried out in the same manner as in Example 2, except that the amount of polyamide resin in the polyamide resin composition (B) was changed.

In Examples 14 to 16, the thickness of the laminated sheet was changed.

In Comparative Example 1, a polyolefin resin composition (A
Example 2 was carried out in the same manner as in Example 2, except that a blowing agent having a decomposition temperature 30° C. higher than the melting point of the polyolefin resin and less than a temperature lower than the melting point of the polyolefin resin was used as the blowing agent.

In Comparative Example 2, a polyamide resin blended composition (B
) as a polyamide resin used in

Same as Example 2 except that a polyamide resin having a melting point lower than a temperature 75 °C higher than the melting point of the polyolefin resin used in the polyolefin resin composition (A) was used, and the extrusion temperature of the laminated sheet was 220 °C. I left it there.

Comparative Example 3 was carried out in substantially the same manner as in Example 2, except that the laminated sheet was heated at a temperature below the decomposition temperature of the blowing agent.

In Comparative Example 4, a polyamide resin blended composition (B
Example 2 was carried out in substantially the same manner as in Example 2, except that the amount of polyamide resin () blended was smaller than the amount limited in the present invention.

In Comparative Example 5, a polyamide resin blended composition (B
Example 2 was carried out in substantially the same manner as in Example 2, except that the blended amount of the polyamide resin () was greater than the amount limited in the present invention.

In Comparative Example 6, a polyamide resin blended composition (B
) The process was carried out in substantially the same manner as in Example 2, except that the layer consisting of ) was not provided.

In Comparative Example 7, a polyamide resin blended composition (B
) was provided in the same manner as in Example 2, except that the calendar consisting of the following was provided only on one side.

Comparative Example 8 was carried out in substantially the same manner as in Example 2, except that only one side of the heat-foamed sheet was cooled instead of being suppressed from both sides.

Comparative Example 9 was carried out in the same manner as in Example 8, except that the polyolefin resin composition (A) was extruded at a temperature equal to or higher than the decomposition temperature of the blowing agent to produce a laminated sheet.

In Comparative Example IO, a polyamide resin blended composition (
The same procedure as in Example 4 was conducted except that the polyolefin resin used in B) was a polyolefin resin of a different type from the resin used in polyolefin resin composition (A).

(Results and evaluation) The results of Examples and Comparative Examples are shown in Table 2.

In all Examples, good foam sheets were obtained.

The results of Examples 6 and 7 show that in the present invention, good foam sheets can be obtained regardless of the amount of foaming agent added.

In Examples 12 and 13, foamed sheets without any problems were obtained. Compared to Example 2, in Example 12, which contained less polyamide resin, the transportability of the laminated sheet was slightly lowered. In addition, in Example 13 in which a large amount of polyamide resin was blended, the adhesiveness between the polyolefin resin composition (A) and the polyamide resin blend composition (B) was slightly decreased.

Therefore, from Examples 2.12 and 13, it can be seen that within the blending ratio range defined in the present invention, it is particularly preferable that the polyamide resin be blended at a ratio of 30 to 60% by weight.

It can be seen from Examples 14 to 16 that good foam sheets can be obtained regardless of the thickness of the laminated sheet.

In all of the comparative examples that did not meet the conditions of the present invention, good foam sheets could not be produced.

In Comparative Example 1, foaming occurred during the production of the laminated sheet, so a good foamed sheet could not be obtained.

In Comparative Example 2, when the laminated sheet was heated and foamed,
A good foamed sheet could not be obtained because the viscosity of the layer of the polyamide resin blended composition (B) decreased or the transportability of the heat-foamed sheet deteriorated significantly.

In Comparative Example 3, foaming did not occur because the heating temperature was low.

In Comparative Example 4, there was a problem in the transferability of the heat-foamed sheet, and in Comparative Example 5, there was a problem in the adhesion between the polyolefin resin composition (A) and the polyamide resin composition (B). .

In Comparative Example 68 and Comparative Example 7, there was a problem in the transportability of the heat-foamed sheets, and good foamed sheets could not be obtained.

In Comparative Example 8, large irregularities occurred on the surface of the foam sheet.

In Comparative Example 9, foaming occurred during the production of the laminated sheet, and a good foamed sheet could not be obtained.

In Comparative Example 10, the polyolefin resin composition (
A) and the polyamide resin blended composition (B) did not adhere to each other, and unevenness occurred on the surface of the foamed sheet.

(Laikong, hereafter in the margin) [Effects of the invention] According to the present invention, it is possible to easily produce foam sheets ranging from low-foaming products to high-foaming products with no unevenness on the surface, and the surface layer is made of polyamide-based Adhesion and printability are improved by providing a resin-containing layer, and as a result,
It is possible to provide an excellent foam sheet that can be suitably used for automobile interior parts and food containers, and a method for manufacturing the same.

Claims (2)

[Claims] (1) On both sides of a layer of a polyolefin resin composition containing a polyolefin resin and a blowing agent, 80 to 30% by weight of a polyolefin resin that is the same as or similar to the polyolefin resin and a polyolefin resin that is the same as the polyolefin resin are added. or 20 to 70% by weight of a polyamide resin having a melting point 75°C or more higher than the melting point of a similar polyolefin resin
A foamed sheet formed by laminating layers of a polyamide resin compound composition containing. (2) A sheet is formed by molding a polyolefin resin composition containing a polyolefin resin and a blowing agent having a decomposition temperature 30 to 75 degrees Celsius higher than the melting point of the polyolefin resin at a temperature lower than the decomposition temperature of the blowing agent. 80 to 30% by weight of a polyolefin resin that is the same or similar to the polyolefin resin and a polyolefin resin that is the same or similar to the polyolefin resin. A polyamide-based resin blended composition containing 20 to 70% by weight of a polyamide-based resin having a melting point higher than the melting point of the blowing agent by 75°C or more is laminated, and the resulting laminated sheet is heated to a temperature higher than the decomposition temperature of the blowing agent and the polyamide-based resin at a temperature higher than the decomposition temperature of the blowing agent. A method for producing a foamed sheet, which comprises foaming a sheet layer made of the polyolefin resin composition by heating at a temperature below the melting point of the polyolefin resin composition, and cooling the resulting heat-foamed sheet while holding it down from both sides.