JPH05229022A - Method for manufacturing foam sheet - Google Patents

Abstract

(57) [Summary] [Purpose] A foam sheet having a smooth surface property is obtained by applying a coating material containing a foaming agent to a substrate and then drying it on a cast drum. [Structure] A coating material in which 100 parts by weight of a composition containing one or more kinds of organic polymer compound adhesives and 2 to 40 parts by weight of heat-expandable microcapsules in which a low-boiling-point solvent is enclosed is used as a base material in an amount of 5-150 g / M ² coating, and the coated surface of the microcapsules is higher than the softening temperature of the wall film, for example, 80 to 150.
Press-dry on a cast drum heated to ℃.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foam sheet used as a heat insulating material, a cushioning material, a packaging material, a packing material, a decoration material and the like.

[0002]

2. Description of the Related Art A method for producing a foam using heat-expandable microcapsules is known, for example, Japanese Patent Publication No.
As described in Japanese Patent No. 26524, a coating material obtained by mixing a heat-expandable microcapsule composed of a polystyrene wall film encapsulating n-heptane and an adhesive is applied to a substrate, dried, and then heated to 140 to 150 ° C. To obtain a foam. However, according to this method, the drying of the paint and the foaming by heating are performed in separate steps, and the surface of the formed foam is remarkably rough, so that a foam having a smooth and beautiful surface cannot be obtained. On the other hand, JP-A-56-13683
As described in Japanese Unexamined Patent Publication (Kokai) No. 0, a coating material containing an unsaturated polyester resin, a photo-curing agent and a foaming agent is applied to a base material, and then the coating surface is irradiated with ultraviolet rays to cure and foam the coating material. However, in this case as well, the roughness of the coated surface due to foaming is remarkable and a foam having a smooth and beautiful surface cannot be obtained.

[0003]

The present invention has been made to solve the above-mentioned drawbacks in the conventional production of foams. That is, not only can the drying and foaming treatment of the paint be performed in one step instead of two steps as in the conventional method, but also after foaming due to uneven dispersion of the foaming agent on the surface of the formed foam, coating unevenness, etc. It has become possible to continuously produce a foam sheet having a smooth and beautiful surface with no irregularities in the above, without lowering the foamability.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors have prepared a composition containing one or more organic polymer compound adhesives, and a heat-expandable microcapsule having a low boiling point solvent enclosed therein. After coating the base material with a coating mixture containing, by contacting the coated surface with a heated cast drum,
It is possible to dry and foam the coating layer at the same time,
It has been found that a foam sheet having a smooth and beautiful surface, which is integrated with a substrate and which is composed of uniform fine closed cells, can be continuously and easily manufactured.

The microcapsule foaming agent used in the present invention contains a low boiling point solvent which expands when heated, and since the capsule wall is formed of a thermoplastic polymer, it can be heated above the softening point of the capsule wall. The microcapsule expands and the foam can be easily formed. The low boiling point solvent vaporizes at a temperature below the softening point of the capsule wall. For example, butane, pentane, hexane, etc. are used. As these microcapsules, for example, microspheres manufactured by Dow Chemical Company or Matsumoto Yushi Co., Ltd. can be used. The compounding amount of the microcapsules is 2 to 40 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the adhesive, and when the amount is 2 parts by weight or less, the foaming is not sufficient, and when it exceeds 40 parts by weight, it is rather uniform. Foam cannot be obtained. As the adhesive used in the present invention, all of the usually available adhesives can be used, for example, as an organic solvent-based adhesive,
Acrylic ester adhesives such as methyl poly (meth) acrylate, ethyl poly (meth) acrylate, butyl poly (meth) acrylate or their copolymers, polyesters, polyurethanes, epoxies, polystyrenes Alternatively, these copolymers and the like can be used alone or in combination of two or more. A water-based adhesive may also be used in the present invention, and the adhesive is not particularly limited, and examples thereof include polyurethane and poly (meth).
In addition to emulsions such as acrylic acid ester, polyester, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, vinyl acetate copolymer, hydroxyethyl cellulose, polyvinyl alcohol,
Water-soluble adhesives such as oxidized starch can be used, and these are used alone or as a mixture of two or more kinds.

If necessary, the coating material of the present invention may be blended with colored dyes, fluorescent coatings, antioxidants, ultraviolet absorbers, colored pigments, antistatic agents, surfactants, auxiliary agents such as vegetable oils. Also, white pigments such as calcium carbonate, titanium dioxide, zinc oxide, kaolin clay, talc, aluminum hydroxide, magnesium oxide, diatomaceous earth, satin white, barium sulfate, basic calcium carbonate, silicon dioxide, aluminum oxide are added. You may. In order to facilitate release from the cast drum, if necessary, higher fatty acid type release agents such as calcium stearate and zinc stearate, polyethylene type release agents such as polyethylene emulsion, wax, silicone type, etc. A release agent is added. The compounding amount of the release agent is 100 for the national form of the paint.
0 to 10 parts by weight is preferable with respect to parts by weight. When the amount is 10 parts by weight or more, the stability of the coating material and the surface of the coating layer are deteriorated, which is not preferable.

In the base material used in the present invention, it is necessary that moisture or volatile components such as a solvent in the coating material pass through the base material and be removed from the non-cast surface side when heated and dried on the cast drum. However, as long as this requirement is satisfied, there is no restriction, but examples thereof include paper and non-woven fabric. The paint is prepared by blending the foamable microcapsules with an aqueous solution of an adhesive or an organic solvent solution of an adhesive, and an auxiliary agent such as a release agent, a pigment, etc. are added as necessary. After the adjusted paint is applied on the substrate,
The coated surface is pressed onto a heated cast drum, dried and foamed, and then peeled off from the cast drum. In this case, after coating the coating material, before pressing the coated surface to the cast drum, the coating material may be pre-dried with a usual dryer, but in that case, the content of water or solvent in the coating layer is It is necessary to maintain at 15% or more, and if it is less than 15%, the smoothness of the cast drum is not significantly improved, which is not preferable. The coating amount of paint is 5-150g
/ ^{M 2,} preferably it is necessary to suppress the range of 10 to 100 g / ^{m 2,} in the 5 g / ^{m 2} or less, no foaming, the 60 g / ^{m 2} or more, not only it takes time to dry However, a good foam cannot be obtained. The surface temperature of the cast drum needs to be equal to or higher than the wall film softening temperature of the microcapsule foaming agent and is usually preferably about 80 ° C to 150 ° C, although it depends on the type of the microcapsule wall material.

[0008]

【Example】

Example 1 200 parts by weight of polyurethane emulsion (manufactured by Dainippon Ink, Hydran HW111, solid content: 45%) and expandable microcapsules (Matsumoto Yushi Co., Ltd., Microsphere) 2
After adding 0 part by weight and 1 part by weight of zinc stearate (manufactured by San Nopco Ltd., SN coat, solid content 33%) as a release agent, the mixture was dispersed and mixed with a Cowles disperser to obtain a coating material. Then, using a Mayer bar on a pigment-coated paper having a thickness of 100 μm (Oji Paper Co., Ltd., OK coat), the coating amount after drying was 30 g.
After coating so that the coating amount would be / m ² , the coated surface was pressed onto a cast drum heated to 100 ° C. to dry and foam the coated layer. The foam sheet peeled off from the cast drum consisted of uniformly fine closed cells and had a smooth and beautiful surface.

Example 2 200 parts by weight of polyester emulsion (Dainippon Ink, Boncoat R-137, solid content 45%) was added to 1 part of expandable microcapsules (Matsumoto Yushi Co., Ltd., Microsphere).
After adding 0 parts by weight and 2 parts by weight of zinc stearate (manufactured by San Nopco, SN coat, solid content 33%) as a release agent, the mixture was dispersed and mixed by a Cowles disperser to obtain a coating material. Then, using a Mayer bar on a pigment-coated paper having a thickness of 100 μm (Oji Paper Co., Ltd., OK coat), the coating amount after drying was 30 g.
/ M ² and then dried in a dryer at 100 ° C so that the water content in the coating layer is 20%. Then, the coating layer is pressure-bonded to a cast drum heated to 100 ° C to apply the coating. Drying the layers,
Foamed. The foam peeled from the cast drum consisted of uniformly fine and closed cells and had a smooth and beautiful surface.

Example 3 Polyacrylic acid ester (LR47 manufactured by Mitsubishi Rayon Co., Ltd.)
2. Solid content 40%) To 200 parts by weight of solution, 20 parts by weight of expandable microcapsules (Matsumoto Yushi Co., Ltd., Microspheres) and 5 parts by weight of titanium dioxide were added, and then dispersed and mixed with a Cowles disperser to prepare a paint. Obtained. Then, it was coated on a pigment-coated paper having a thickness of 100 μm (Oji Paper Co., Ltd., OK coat) so that the coating amount after drying would be 20 g / m ² , and the coated surface was pressure-bonded to a cast drum with a surface temperature of 110 ° C. Then, the coating layer was dried and foamed. The foam peeled from the cast drum is
It consisted of uniformly fine closed cells and had a smooth and beautiful surface.

Comparative Example 1 100% was applied without pressing the coated surface to the cast drum.
The same procedure as in Example-1 was repeated except that the paint was dried and foamed in a dryer maintained at 0 ° C. to obtain a foam. The surface of the obtained foam was rough, and the surface irregularities were remarkable.

Comparative Example 2 100% was applied without pressing the coated surface to the cast drum.
The same operation as in Example-3 was repeated except that the paint was dried and foamed in a dryer maintained at 0 ° C. to obtain a foam. The surface of the obtained foam was rough, and the surface irregularities were remarkable.

[0013]

[Table 1]

[0014]

EFFECTS OF THE INVENTION By using the present invention, it is possible to continuously and easily produce a foam comprising fine closed cells having a smooth and beautiful surface, which is integrated with a base material without any deterioration in foamability. Became.

Claims (1)

[Claims] 1. A composition prepared by mixing one or more organic polymer compound-based adhesives with a heat-expandable microcapsule containing a low boiling point solvent inside is coated on a substrate, and then the coated surface is heated. By contacting the cast drum
A method for producing a foam sheet, which comprises simultaneously drying and foaming a coating layer.