JPS6136786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flexible vinyl chloride resin foam, particularly a sheet-like foam.

Conventionally, foamed sheets made of soft vinyl chloride resin used for flooring materials, wall interior materials, etc. are made mainly from vinyl chloride resin powder with a very small particle size obtained by emulsion polymerization method, so-called paste resin. , by adding various additives such as plasticizers, stabilizers, foaming agents, etc., and uniformly mixing the mixture, pouring it evenly onto the substrate using a paste processing machine, heating and foaming it, and then peeling it off from the substrate. It has been obtained.

However, vinyl chloride resin produced by emulsion polymerization method is
Due to the fineness of the particles, it is very difficult to handle.
Also, suspension polymerization has many advantages in terms of production, and therefore most vinyl chloride resins other than those for special uses are manufactured by the suspension polymerization method.
Even if a suspension polymer product is processed in the same manner as an emulsion polymer product to produce a foam, only a coarse-grained foam can be obtained.
Furthermore, even if a foaming agent is blended into a suspended polymer product, a sheet is made using a calendar or an extruder, and the sheet is heated and foamed in an oven, a fine-grained foam cannot be obtained. Therefore, it would be of great industrial significance if a finer-textured foam similar to or better than that obtained from emulsion polymerization products could be obtained from suspension polymerization products using a calendar or an extruder. There is a thing.

Based on this understanding, the inventors of the present invention have conducted various studies in order to obtain a vinyl chloride resin foam with a fine-grained, homogeneous and flexible texture from vinyl chloride resin using the suspension polymerization method. It has been discovered that this problem can be solved by adding a small amount of surfactant to the product, and the present invention has been achieved.

That is, the present invention involves adding a plasticizer, a blowing agent, and other additives to vinyl chloride resin powder obtained by a suspension polymerization method, mixing them uniformly, making a sheet using a calender or an extruder, and heating the sheet. This is a method for producing a vinyl chloride resin foam, which is characterized in that when producing the foam, a surfactant is added to the raw material in an amount of at least 0.1 PHR or more based on the vinyl chloride resin.

The vinyl chloride resin used in the present invention may be produced by a conventional suspension polymerization method, but those having a degree of polymerization of about 1000 to 3500 are particularly suitable for this use. It is also possible to use copolymers based on vinyl chloride with small amounts of other monomers, such as vinyl acetate.

Plasticizers are added as appropriate depending on the desired flexibility of the product, but usually DOP (dioctyl phthalate) is used.
Add approximately the same amount of vinyl chloride resin. Also foaming agent,
The stabilizers and other additives may be the same as those normally used in paste resins. That is, as the foaming agent, azodicarbonamide is the most typical and easy to use, and its addition amount may be about 3 to 5 PHR, and as the stabilizer, Ba and Zn based metal soaps are preferably used.

Other additives such as lubricants, fillers, pigments, etc. that are normally used for vinyl chloride or foams thereof may be added as necessary.

The most typical surfactant used in the present invention is anionic sodium dodecylbenzenesulfonate, but various anionic surfactants including other alkali salts of alkylbenzenesulfonate can be mentioned. Similar effects can be obtained by using either an active agent, a nonionic surfactant, or a mixture thereof. The appropriate amount to add will vary depending on the type of surfactant, but it should be at least 0.1PHR, preferably 0.3~
Approximately 2.0 PHR is sufficient; adding more than a certain amount will not increase the effect and will actually worsen the foaming state.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1, Comparative Example 1 DOP was added as a plasticizer to 100 parts of vinyl chloride resin powder with a degree of polymerization of 1800 obtained by suspension polymerization method.
(dioctyl phthalate) 100 parts, azodicarbonamide 3 parts as a blowing agent, polyethylene wax 0.5 parts as a lubricant, calcium carbonate 15 as a filler.
LBZ-732M (Ba-Zn soap,
2 parts (manufactured by Sakai Chemical Co., Ltd.), EVA (ethylene-vinyl acetate copolymer, manufactured by Nippon Gosei Kagaku Co., Ltd.) as a foaming aid
A raw material containing 2 parts of CI-S) and 15 parts of sodium dodecylbenzenesulfonate as a surfactant was thoroughly kneaded with a roll, and then a sheet with a thickness of 1 mm was produced with a calender roll. This was placed in an oven kept at 210°C and heated for 5 minutes to foam, thereby obtaining the desired soft vinyl foam. The foaming ratio is
Observation of the foam surface and cross section revealed that the foam was fine and fine, comparable to that made from paste resin by emulsion polymerization. On the other hand, the product made and foamed under the same conditions without adding sodium dodecylbenzenesulfonate (Comparative Example 1) has a foaming ratio of 1.70.
The foamed state was rough and unsuitable for practical use.

Example 2, Comparative Example 2 100 parts of vinyl chloride resin powder with a degree of polymerization of 1800 by suspension polymerization method, 100 parts of DOP, 2.5 parts of Ba-Zn stabilizer (LBZ-213F manufactured by Sakai Chemical Co., Ltd.), 15 parts of calcium carbonate
A sheet was prepared in the same manner as in Example 1 using a blend of 3 parts of EVA, 3 parts of azobisisobutyronitrile (a blowing agent), and 1.0 part of sodium dodecylbenzenesulfonate, and treated in an oven at 220°C for 5 minutes. A fine-grained foam with an expansion ratio of 400 times was obtained. On the other hand, when no surfactant was added in the above formulation (Comparative Example 2), the foaming ratio was
Only a foam with a texture 36 times rougher was obtained.

Example 3, Comparative Example 3 Using 100 parts of powder of a vinyl chloride-vinyl acetate copolymer resin with a degree of polymerization of 1500 and a vinyl acetate content of 5% by weight obtained by a suspension polymerization method, the amount of sodium dodecylbenzenesulfonate added was A sheet and a foam were produced under the same conditions as in Example 2 except that the PHR was 1.5 PHR. As a result, fine-grained, uniform, and flexible foaming with a foaming ratio of 4.3 times was obtained. On the other hand, the foam produced above without adding sodium dodecylbenzenesulfonate under the same conditions had an expansion ratio of 3.9 times, but only a foam with large cells and a poor surface condition was obtained.

Claims (1)

[Claims] 1. Plasticizers, blowing agents, and other additives are added to vinyl chloride resin powder obtained by a suspension polymerization method, mixed uniformly, and then a sheet is made using a calender or extruder. 1. A method for producing a vinyl chloride resin foam, which comprises adding a surfactant to the raw material in an amount of at least 0.1 PHR based on the vinyl chloride resin when producing the foam by heating the foam. 2. The method for producing a vinyl chloride resin foam according to claim 1, wherein the surfactant is an alkali salt of alkylbenzenesulfonic acid. 3. The method for producing a vinyl chloride resin foam according to claim 2, wherein the alkali salt of alkylbenzenesulfonic acid is sodium dodecylbenzenesulfonate.