JPH03169534A - Manufacture of olefinic resin open-cell foam - Google Patents

Abstract

PURPOSE:To constitute the manufacture so that a long-sized open-cell foam where the skin and a foam are unified completely, it is free from creases and unevenness and its surface is smooth and favorable can be obtained easily and at favorable productivity, by a method wherein at the time of lamination of a skin film to the open-cell foam, foaming is performed after the skin film is fused thermally to a foamable sheet beforehand. CONSTITUTION:A composition for an open-cell foam containing olefin resin and a foaming resin is molded in a sheetlike state, one side is pressure-contacted to a substrate surface having a smooth surface and then the same is foamed by heating the same at the decomposition temperature or higher. A pellet is molded into a sheet whose thickness is 0.5mm and width is 500mm by making use of 50mm extruding machine and introduced continuously into a foaming machine having an endless belt 4 made of polytetrafluoroethylene and a heating furnace 7. In this instance, simultaneously with the above, a film 5 made of ethylene-vinyl acetate copolymer resin whose thickness is 0.1mm and width is 600mm is fed between a press roll 6 and the foamable sheet 2, passed through a heating furnace 7, whose atmospheric temperature is 200 deg.C, while pinching continuously and foaming is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for producing an olefinic resin open-cell foam having a smooth surface without wrinkles or irregularities, in which the skin and the open-cell foam are integrated.

[Prior art] By laminating a film as a skin on the surface of an olefin resin foam, a foam with a smooth surface can be obtained, and if a printed film or a functional film is used, a foam with high added value can be obtained. It becomes possible to produce foam.

Conventionally, heat fusion methods, adhesive methods, and the like have been generally used for laminating olefin resin foams and plastic films.

Heat fusion methods are primarily used for closed cell foams. In closed-cell foams, the air within the cells effectively acts as a repellent against compression during heat-sealing, so the cells and the thickness of the foam can be sufficiently maintained even after the film is heat-sealed. However,
In the case of open-cell foam, resistance to heating and compression during thermal fusion is low, resulting in destruction of the cells and a decrease in the thickness of the foam. Therefore, for laminating the open-cell foam and the film, a method is used in which they are integrated using an adhesive.

However, in the case of the adhesive method, the processing process is complicated,
Furthermore, there are disadvantages in that the yield is reduced and the cost of the adhesive increases the overall cost.

As a way to prevent the destruction of open cells and the decrease in foam thickness,
Pressure-sensitive adhesives have also been used, but they similarly have the drawbacks of complicated processing steps, lower yields, higher overall costs due to the cost of adhesives, and insufficient adhesive strength.

Methods for manufacturing open-cell foams that have already been proposed (JP-A-56-121739, JP-A-57-1910
In No. 27), the surface of the foam obtained is a sliced surface, and laminating the skin thereon has the above-mentioned problems.

When the open-cell foam composition proposed in Japanese Patent Publication No. 60-49657 is used, an open-cell foam with a skin can be obtained, but since this is a skin that accompanies foaming, the diameter of the generated cells is It has unevenness, insufficient surface smoothness, and low mechanical strength.

[Problems to be solved by the present invention]

An object of the present invention is to provide an olefinic resin open-cell foam having a smooth surface without wrinkles or irregularities, in which a skin made of a plastic film and an open-cell foam are integrated.

Another object of the present invention is to provide an efficient method for integrally laminating a skin film on an open-cell foam without using an adhesive.

As a result of intensive research to overcome the problems of the prior art, the present inventors have found that when laminating a film as a skin on an open-cell foam, the use of an open-cell foam containing an olefin resin and a blowing agent. In the method of molding the composition into a sheet and heating and foaming it on a support, an olefin resin film is fused and laminated onto a foamable sheet in advance, and the film is completely adhered to the surface by heating and foaming. It has been found that it is possible to efficiently produce an open-cell olefin resin foam sheet with a smooth surface without wrinkles or irregularities.

It has also been found that this method can achieve better foaming efficiency than conventional methods.

Further, as a support, for example, an endless belt is used, and a film that becomes the skin is continuously supplied onto the foam sheet that is continuously extruded from an extruder before the foam sheet is cooled and solidified. It has been found that a series of operations can be carried out efficiently and continuously by pressing with a pressure roll or the like and fusing and laminating.

The present invention has been completed based on these findings.

[Means to solve the problem]

Thus, according to the present invention, a composition for an open-cell foam containing an olefin resin and a blowing agent is molded into a sheet, one side of this foamable sheet is pressed onto the surface of a support having a smooth surface, and then, In a method for producing an open-cell olefin resin foam, which involves heating the foam to a temperature higher than the decomposition temperature of the blowing agent to foam the resulting open-cell foam, and then peeling it off from the support, the open-cell foam is peeled off from the support. Provided is a method for producing an open-cell olefin resin foam, which comprises fusing and laminating an olefin resin film on the other surface that is not covered by the foam, and then heating the product to a temperature higher than the decomposition temperature of the blowing agent.

The present invention will be explained in detail below.

(Composition for open-cell foam) The composition for open-cell foam used in the present invention is not particularly limited, and includes conventionally known compositions.

Among these, the following compositions are particularly preferred.

■ A composition containing an olefin resin, a blowing agent, and an α-olefin modified surfactant.

■ A composition containing an olefin resin, a blowing agent, an α-olefin modified surfactant, and an organic peroxide.

■ A composition containing an olefin resin, a blowing agent, an α-olefin modified surfactant, an organic peroxide, and a process oil.

■ A composition containing an olefin resin, a blowing agent, a methylphenyl-modified surfactant, and an organic peroxide.

Examples of olefin resins include ethylene-vinyl acetate copolymer, ethylene-brobylene copolymer, ethylene-brobylene-diene copolymer, ethylene-acrylate copolymer, and blends of these copolymers. High, medium and low density polyethylene, chlorinated polyethylene, polypropylene and the like can be mentioned.

These compositions also contain zinc compounds, urea compounds, zinc chloride compounds, etc. to adjust the decomposition temperature of the blowing agent.
Antibacterial agents, antifungal agents, deodorants, etc. may be added.

Such compositions for open-cell olefin resin foams are disclosed in Japanese Patent Application Laid-Open No. 62-223 filed earlier by the present inventors.
No. 243, JP-A-63-159448, JP-A-63-
268748, JP-A No. 3-309535, etc. can be used, and if a sheet of these compositions is heated and foamed under normal pressure, it will have a uniform cell structure. An open-celled foam is obtained.

(Olefin-based resin film) The olefin-based resin film used in the present invention has heat-fusibility with the olefin-based resin used in the open-cell foam composition, or has been modified or modified to provide heat-fusibility. Any film made of surface-treated material may be used.

Specific examples include ethylene-vinyl acetate copolymer, high
Examples include films of medium and low density polyethylene and polypropylene.

The olefin resin film preferably has a dimensional change rate of (±) 5.0% or less, more preferably 2.0% or less, from the melting point of the film material to room temperature. If the dimensional change is greater than 5.0%, the entire foam may become curved due to shrinkage of the film during cooling after foaming, uneven thickness may occur, or the support may be deformed, resulting in a poor quality of the foam. It becomes difficult to obtain. In particular, the dimensional change rate is 0.
．． A range of 3 to 5.0% is preferable in order to obtain a smooth foam sheet.

There are no particular restrictions on the thickness of the film, but if it is too thin, it will be difficult to obtain a smooth surface, and if it is too thick, it will be difficult to form a foam sheet, so preheating is required. be.

(Manufacturing method) In the present invention, an open-cell foam composite containing an olefin resin and a T-wrapping agent is prepared at a temperature above the melting point of the resin and below the decomposition temperature of the blowing agent using an extruder or calender roll. Melt and knead and form into a sheet.

One side of the foamed sheet obtained in this way is pressed onto the surface of a support with a smooth surface and usually non-porous, so that no air is present, and the film is heat-sealed to the other side. and laminate.

When heat-sealing a film, heat the foam sheet, support, and film in advance, and then press the film onto the foam sheet with a pressure roll or the like to make the pressure bond easier and more tightly bonded. This is preferable because a state in which the material is in close contact with the material can be obtained.

In addition, in order to make production more efficient, an extruder is used to mold the foam sheet, and the foam composition is melt-extruded through a slit-shaped die into a sheet shape, transferred onto a support, and then foamed. There is a method in which, before the plastic sheet is cooled and solidified, a heat-adhesive film is pressed onto its surface using a pressure roll, an air knife, etc., and then introduced into a heating furnace, heated, and foamed.

When an olefin resin film is fused and laminated on the surface of a foamable sheet, the size of the film is usually preferably the full width and length of the foamable sheet. Thereby, the foaming gas is trapped inside by the film, and the foaming ratio can be increased.

Materials for the support used in the present invention include steel, fluororesin, silicone rubber, fluororesin-coated cloth, fluororesin-coated glass cloth, etc.The material has a smooth surface, no air permeability, heat resistance, releasability, and mechanical resistance. One with good durability is preferable. A mesh type support with air permeability can also be used, but it is not very preferable because it has problems such as mold releasability and leaving a specific pattern on the surface of the foam.

Moreover, in order to obtain a long foam, it is preferable to use a support consisting of an endless conveyor belt.

FIG. 1 and FIG. 2 are diagrams showing an embodiment of the manufacturing method of the present invention.

FIG. 1 is a schematic diagram showing a method for continuously producing an open-cell olefin resin foam using an extruder. The foam sheet ■ melted and extruded from the extrusion mold ■ is transferred onto an endless conveyor belt ■, and a film ■ is supplied onto the surface of the conveyor belt ■, which is pressed onto the foam sheet surface by a press roll ■. be done. Thereafter, the laminated foamable sheet is introduced into a heating furnace (1) and heated and foamed.

FIG. 2 is a diagram showing a method of preheating a foamable sheet, a support, and a film using a heater, and then pressing the film onto the foamable sheet with a pressure roll or the like. The foam sheet (2), the endless conveyor belt (2), and the film (2) are heated in advance by a heating heater (2), and are pressed and bonded by a pressure roll (2).

[Examples] The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited only to these Examples.

[Example 1] An olefin resin having a melt index MI of 7.
0, 100 parts by weight of ethylene-vinyl acetate copolymer with an acetic acid content of 6% by weight, 8 parts by weight of azodicarbonamide as a blowing agent, 2 parts by weight of urea and 2 parts by weight of zinc oxide, α-olefin modified surfactant ( 2 parts by weight of silicone (50% modified by C, H,.) were mixed in a roll mill at 110°C to form a pellet.

This pellet was made using a 50mm extruder to a thickness of 0.5m.
This sheet was formed into a sheet having a width of 500 mm and a width of 500 mm, and this sheet was continuously introduced into a foaming machine equipped with an endless belt made of polytetrafluoroethylene and a heating furnace using the apparatus shown in FIG.

At this time, the foam sheet is transferred to the endless belt, and at the same time, between the press roll and the foam sheet, a zero
．． A film having a thickness of 1 mm and a width of 600 mm was supplied, and while being continuously compressed, it was passed through a heating furnace at an ambient temperature of 200° C. to perform foaming. After cooling, the foam was peeled off from the endless belt to obtain an open-cell foam with an integrated skin film.

The obtained foam had a uniform cell structure with an average cell diameter of 0.35 mm, and the skin film surface was very smooth and completely integrated with the foam.

The foaming ratio is 17.0cc/without the film.
It was g. Further, the closed cell ratio measured with an air comparison type hydrometer was approximately 0%.

The dimensional change rate of the ethylene-vinyl acetate copolymer resin film used from the melting point to room temperature was -1.8%.

[Example 2] Instead of the main tyrene-vinyl acetate copolymer resin film used in Example 1, linear low-density polyethylene (density: 0) was used.
．． 920, MI is 2.0) thickness 0.05 mm, width 600 mm, dimensional change rate from melting point to room temperature -1
．． An open cell foam with a skin film was produced in the same manner as in Example 1, except that a 1% film was used.

The obtained foam had a uniform cell structure with an average cell diameter of 0.35 mm, and the skin film surface was very smooth and completely integrated with the foam.

The foaming ratio is 17.0cc/without the film.
g, and the thickness was 8.5 mm. Further, the closed cell ratio measured with an air comparison type hydrometer was approximately 0%.

[Comparative Example 1] Foaming was carried out using only the foamable sheet without using the film in the same manner as in Example 1.

The obtained foam was a good foam with a uniform cell structure; however, although the surface of the foam appeared to be smooth at first glance, upon closer observation, it was found to have small irregularities due to air bubbles.

In addition, the foaming ratio is 15cc/g and the thickness is 7.5m.
It was m.

[Comparative Example 2] Instead of the ethylene/vinyl acetate copolymer resin film used in Example 1, high-density polyethylene (density: 0.9
54, MI is 1.1) thickness 0.05mm, width 60
0mm, the rate of dimensional change from melting point to room drift is -
An open cell foam with a skin film was produced in the same manner as in Example 1, except that a 5.5% film was used.

The obtained foam is a good foam with a uniform cell structure, and the film and foam are completely integrated.
The film surface of the skin was also very smooth, but due to the large dimensional change rate of the film, contraction in the width direction occurred during cooling, deforming the polytetrafluoroethylene endless belt, and causing the foam to shrink in the width direction. The thickness became uneven.

The foaming ratio in the area where the thickness of the obtained foam was relatively uniform was 17.0 cc/g, and the thickness was 8.5 mm.

[Effects of the Invention] According to the present invention, when laminating a skin film on an open-cell foam, by heat-sealing it to a foamable sheet in advance and then foaming it, the skin and the foam are completely integrated and wrinkles are eliminated. It is possible to easily provide a long open-cell foam with a smooth surface and no unevenness, and with good production efficiency.

Furthermore, according to the method of the present invention, it is also possible to produce foams with high added value by using printed films and functional films.

Furthermore, the decomposed gas of the blowing agent is trapped between the support and the skin film and is effectively used for foaming, making it possible to easily obtain a foam with good foaming efficiency and high magnification.

The open-cell foam obtained by the present invention has excellent water absorption, weather resistance, and water resistance, is flexible, has good compression recovery properties, and has excellent tactile sensation. Used as lumber etc.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing an embodiment of the manufacturing method of the present invention. ■... Extrusion mold, ■... Foaming sheet, ■...
・・Heater ■・Endless belt made of polytetrafluoroethylene, ■・Skin film, ■・Press roll, ■・Heating furnace.

Claims (3)

[Claims] (1) A composition for an open-cell foam containing an olefin resin and a blowing agent is molded into a sheet, one side of this foamable sheet is pressed onto a support surface with a smooth surface, and then the decomposition temperature of the blowing agent is In a method for producing an olefinic resin open-cell foam, which involves heating and foaming as described above, cooling the obtained open-cell foam, and then peeling it off from a support, the other surface of the expandable sheet that is not in contact with the support surface A method for producing an open-cell olefin resin foam, which comprises fusing and laminating an olefin resin film and then heating it to a temperature higher than the decomposition temperature of a blowing agent. (2) The manufacturing method according to claim 1, wherein the olefin resin film has a dimensional change rate of 5.0% or less from its melting point to room temperature. (3) Melt-extrude the open-cell foam composition using an extruder to form it into a sheet, transfer this foamable sheet onto a support and press it, and before the foamable sheet is cooled and solidified, The manufacturing method according to claim 1 or 2, wherein an olefin resin film is continuously supplied onto the surface and fused and laminated by pressing and bonding.