JPH0768396B2 - Water-swellable polyvinyl chloride foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a water-swellable polyvinyl chloride foam suitable as a water blocking material and the like.

<Prior art and its problems> Water-swelling polyvinyl chloride foam is
It is used as a water stop material and is described in JP-A-58-32638. However, the conventional water-swellable polyvinyl chloride foams described in JP-A-58-32638 and the like have a problem that the skin of the product is poor and the mechanical strength in a water-containing state is lowered. It was On the other hand, if the expansion ratio is kept low, the skin will be improved, but the swelling speed due to water absorption will be remarkably slowed, and the performance as a foam will be reduced. That is, the conventional water-swellable polyvinyl chloride foam has a poor balance between the swelling rate due to water absorption and the skin of the product.

<Means for Solving the Problems> As a result of studies to solve the above problems, the present inventor has found that the composition of conventional water-swellable polyvinyl chloride foams is polyvinyl chloride / plasticizer / high water absorption. The inventors have found that the addition of a small amount of a rubber component to a resin / foaming agent makes it possible to obtain a water-swellable polyvinyl chloride foam which has a high swelling speed due to water absorption and has a good product skin. That is, the present invention comprises polyvinyl chloride, a plasticizer, a super absorbent polymer, a foaming agent and a rubber component, and the amount of the rubber component is 1 to 30 parts by weight based on 100 parts by weight of the total amount of polyvinyl chloride and the plasticizer. It is a water-swellable polyvinyl chloride foam formed by foaming a composition.

As the polyvinyl chloride used in the present invention, various known polyvinyl chloride homopolymers, random copolymers, random copolymers, block copolymers, graft polymers and the like are used. You may mix and use the above.

Examples of the plasticizer used in the present invention are those usually used for vinyl chloride resins and include dioctyl phthalate, dibutyl phthalate, butylbenzyl phthalate, dibutyl adipate, dioctyl adipate and the like. Also, a commonly used secondary plasticizer such as epoxidized soybean oil may be used in combination.

The superabsorbent resin is not particularly limited, and various conventionally known resins can be used. Specifically, a saponified product of vinyl acetate-acrylic acid ester copolymer, a crosslinked product of a modified isobutylene-maleic anhydride copolymer, polyacrylic acid (salt) having a crosslinked structure, starch-acrylic acid (salt) graft weight Examples of the compound include a polymer compound containing a carboxylate in the molecule (for example, a saponified product of vinyl acetate-acrylic acid ester copolymer, a crosslinked product of a modified isobutylene-maleic anhydride copolymer). ) Is particularly preferably used because it has excellent durability. Two or more kinds of such super absorbent polymers may be used in combination.

The water absorption performance of the super absorbent polymer is 20 g / g or more, especially 100 g / g.
It is preferably g or more, and the smaller the average particle diameter is, the more preferable. Generally, it is 100 μm or less, and particularly preferably 30 μm or less. When the average particle size exceeds 100 μ, the water swelling polyvinyl chloride foam thus obtained tends to be deteriorated in water swelling property and mechanical strength, or the super absorbent polymer tends to fall off during water swelling.

The rubber component used in the present invention is natural rubber (NR),
Acrylonitrile-diene copolymer rubber (NBR or NI
R), synthetic cis-1,4-polyisoprene rubber (IR), styrene-diene copolymer rubber (SBR or SIR), butadiene rubber (BR), isobutylene-isoprene copolymer rubber (II
R), chloroprene rubber (CR), isoprene rubber (I
R), ethylene-propylene copolymer rubber (EP), urethane rubber, styrene thermoplastic elastomer, etc. are exemplified, but natural rubber, isoprene rubber or acrylonitrile-diene copolymer rubber is preferable.

As the foaming agent used in the present invention, known foaming agents can be used, such as diazoamino derivatives, azonitriles, azodicarboxylic acid derivatives, dinitropentamethylenetetramine,
Examples thereof include benzene monohydrazole, oxybisbenzenesulfonyl hydrazide, ammonium bicarbonate and the like.

The water-swellable polyvinyl chloride foam of the present invention comprises the above-mentioned polyvinyl chloride, a plasticizer, a highly water-absorbent resin, a foaming agent and a rubber component, and further a foaming accelerator or a foaming inhibitor and various additives described later if necessary. It is manufactured by mixing and heating and foaming. The mixing ratio of the rubber component is 1 to 30 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of polyvinyl chloride and the plasticizer. If the compounding ratio of the rubber component is too large, the swelling speed will be lowered, and if it is too small, the skin of the product will be deteriorated and the object of the present invention cannot be achieved.

The compounding ratio of polyvinyl chloride, a plasticizer, a super absorbent resin, a foaming agent, and a rubber component varies depending on the use, but the weight ratio of polyvinyl chloride / plasticizer is preferably 0.6 to 2.5, and polyvinyl chloride and the plasticizer. Is 100 to 100 parts by weight per 100 parts by weight. Although the amount of the foaming agent varies depending on the use, it is preferably in the range of 0.1 to 5 parts by weight based on 100 parts by weight of polyvinyl chloride, the plasticizer, the super absorbent polymer, and the rubber component.

If necessary, a stabilizer, a dispersant, a filler, a colorant, an antistatic agent, a weatherproofing agent, an antifungal agent, etc. may be mixed when the above mixture is prepared.

Next, a method of mixing will be described. First, polyvinyl chloride, a plasticizer, a superabsorbent resin and a rubber component are uniformly mixed by a mechanical method such as roll kneading, Banbury kneading, kneading with an extrusion mixer equipped with a dullage screw, heating kneader kneading, etc. Perform pelletization. Further, the pellets are dry-blended with an appropriate amount of a foaming agent and the like, and then formed into a string, a sheet, a film, a molded product or the like depending on the purpose of use. In addition, such kneading and molding processing is usually 130
It is preferably carried out at a temperature of ~ 180 ° C. Depending on the superabsorbent resin, the adsorbed water may be released in this temperature range, but by removing the adsorbed water from the superabsorbent resin in advance, a stable and dense foam can be obtained. Examples of the method for molding the water-swellable polyvinyl chloride foam of the present invention include commonly used methods such as extrusion foaming method, press foaming method and calender foaming method. Particularly in the case of forming a string-shaped waterproofing agent, the extrusion foaming method is preferable because it is inexpensive and the shape can be arbitrarily changed.

<Effects of the Invention> The water-swellable polyvinyl chloride foam of the present invention has a better product skin than conventional ones, and therefore the mechanical strength in the water-containing state is less decreased and the swelling rate due to water absorption is large. .
And it is used alone or in combination with non-swelling polyvinyl chloride resin as a gap waterproofing material, sealing material, packing, waterproofing board, etc. in the field of civil engineering, construction, etc. Can be obtained.

<Example> Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Example 1 A polyvinyl chloride / dioctyl phthalate / super absorbent polymer (vinyl acetate-
Saponified acrylic ester copolymer, trade name Sumika gel
Water-swellable polyvinyl chloride resin (Sumikagel GRC.VCL-3, Sumitomo Chemical Co., Ltd.) made from a 1/1/1 composition of SP-510) and natural rubber (RSS # 3) 100% by weight 5 parts by weight of the latter was added to 5 parts by weight, and the mixture was kneaded for 5 minutes and pelletized. After dry-blending 0.5 part by weight of an azodicarbonamide-based foaming agent (Celmic CAP-149, manufactured by Sankyo Kasei Co., Ltd.) with 100 parts by weight of the pellet, a string having a cross section of 20 mm x 3 mm at a resin temperature of 150 ° C using a 40 mmφ extruder. A foam was obtained. The result of measuring the physical properties of the obtained foam is the second
Shown in the table.

Example 2 Instead of natural rubber, isoprene rubber (2200, made by Zeon)
A water-swellable polyvinyl chloride foam of the present invention was obtained in the same manner as in Example 1 except that was used. The results of measuring the physical properties of the obtained foam are shown in Table 2.

Example 3 Polyvinyl chloride, di- (2-hexyl) phthalate, cross-linked product of isobutylene-maleic anhydride copolymer modified product (KI gel 201K, average particle size about 8μ, manufactured by Kuraray Isoprene Co.), acrylonitrile-butadiene copolymer Polymerized rubber (N230
SV, made by Japan Synthetic Rubber Co., Ltd.) and foaming agent SELMIC CAP-149
Was used in the same manner as in Example 1 to obtain a water-swellable polyvinyl chloride foam of the present invention. The results of measuring the physical properties of the obtained foam are shown in Table 2.

Comparative Example 1 A string-like foam was obtained in the same manner as in Example 1 except that natural rubber was not used. The results of measuring the physical properties of the obtained foam are shown in Table 2.

Comparative Example 2 A string-like foam was obtained in the same manner as in Example 3 except that the acrylonitrile-butadiene copolymer rubber was not used. The results of measuring the physical properties of the obtained foam are shown in Table 2.

Claims (2)

[Claims] 1. A polyvinyl chloride, a plasticizer, a super absorbent resin,
A water-swellable polyvinyl chloride foam formed by foaming a composition comprising a foaming agent and a rubber component, the amount of the rubber component being 1 to 30 parts by weight based on 100 parts by weight of the total amount of polyvinyl chloride and a plasticizer. . 2. A water-swellable polyvinyl chloride foam according to claim 1, wherein the rubber component is natural rubber, isoprene rubber or acrylonitrile-diene copolymer rubber.