JP3236008B2 - Method for producing polyvinyl chloride resin foam - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polyvinyl chloride resin foam used for cushions, life jackets, floats, buoyancy materials, cushioning materials and the like.

[Prior art and problems] Conventionally, a polyvinyl chloride resin foam is kneaded with a raw material such as a plasticizer, a foaming agent, a stabilizer, or the like, or compounded into a paste, and filled in a mold. And
After the foaming agent is decomposed by heating and pressurizing, the mold is released at normal temperature and the mold is released to take out the primary foam. Then, the primary foam is heated and gradually foamed to obtain a final foam.

In this case, the primary foam is substantially the same size as the mold or is at most twice as large as it cools to approximately room temperature.
Therefore, conventionally, this is conventionally placed in an oven or the like and reheated to gradually form secondary foam, but it takes a lot of time and productivity is reduced.

Also, if foaming is performed at once without cooling to room temperature as described above, phenomena such as bubbles falling apart or the strength of the foam not being obtained occur, and the desired foam cannot be obtained. There is a problem that.

The present invention has been made in view of the above circumstances, after obtaining a primary foam, subsequently, by heating this primary foam free and foaming to obtain a secondary foam, to shorten the foaming time A method for producing a polyvinyl chloride resin-based foam capable of improving productivity can be provided.

[Means for Solving the Problems] The present invention adds 15 to 100 parts by weight of a nitrile rubber, a foaming agent, a crosslinking agent, and a plasticizer to 100 parts by weight of a polyvinyl chloride resin, and kneads the mixture to form a mixture. Thereafter, the mixture was filled in a mold, heated and pressurized by a press machine, and further released from the mold to obtain a primary foam. Subsequently, the primary foam was heated and foamed to form a secondary foam. A method for producing a polyvinyl chloride resin-based foam, characterized by being obtained.

In the present invention, the range of the nitrile rubber is limited as described above.If the addition amount is less than 15 parts by weight, the foaming stability cannot be obtained, and if the addition amount exceeds 100 parts by weight, the characteristics of the polyvinyl chloride resin are reduced. Because it gets worse. The nitrile rubber has good compatibility with the vinyl chloride resin, and examples thereof include NBR (nitrile butadiene rubber) and nitrile rubber.

In the present invention, examples of the foaming agent include azodicarbonamide, dinitrosopentamethylenelatramine and the like.
Add about 25 parts by weight.

In the present invention, examples of the crosslinking agent include sulfur.

In the present invention, the plasticizer imparts flexibility to the foam to be formed, and includes general ones such as DOP, DBP, and DOA.

In the present invention, not only a nitrile rubber, a foaming agent, a crosslinking agent and a plasticizer may be added to the vinyl chloride resin, but also a coloring agent and a filler may be added if necessary. Here, barium stearate, zinc stearate or the like is used as a stabilizer.

[Function] In the present invention, since the primary foam is a medium foam of about 3 to 7 times without cooling, secondary foaming can be performed in a short time. Also, in the primary foam, the nitrile rubber, which has good compatibility with vinyl chloride resin, is cross-linked,
A medium-sized foam having a holding power for bubbles is obtained.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

Vinyl chloride resin (trade name # 25, manufactured by Zeon Corporation) 100 parts by weight NBR (nitrile rubber) 30 parts by weight DOP (plasticizer) 80 parts by weight Zinc oxide 3.0 parts by weight Barium stearate (stabilizer) 1.5 parts by weight Azo Dicarbonamide 16 parts by weight Noxeller TET (promoter) 0.7 parts by weight Sulfur (crosslinking agent) 1.5 parts by weight First, the mixture was kneaded with the above formulation to obtain a mixture. Subsequently, the mixture was almost completely filled in a mold 1 having an inner size of 10 × 150 × 150 mm, and heated and pressed at 148 ° C. for 14 minutes using a press machine 2 (see FIG. 1 (A)). Thereafter, the press 2 was released as it was without cooling, and the mold 1 was further released to obtain a primary foam 3 (shown in FIG. 1 (B)). Here, the dimensions of the primary foam 3 are, for example, 16 × 230 × 230 mm.

Next, the primary foam 3 was placed in an oven 4 at 170 ° C. and heated free for 6 minutes (see FIG. 1 (C)).
As a result, a secondary foam (final foam) 5 having a size of about 25 × 400 × 400 mm was obtained. This final foam has a density of 0.05 g / cm ³
Was a very soft, closed cell foam.

As described above, according to the present invention, a mixture obtained by mixing NBR or the like having good compatibility with a vinyl chloride resin is filled almost completely in a mold 1, and is pressed at an arbitrary temperature and time using a press machine 2. After heating and pressurizing, the press 2 is released as it is without cooling, and the mold 1 is further released to obtain a primary foam 3. Subsequently, the primary foam 3 is heated and foamed free. The secondary foam 5 is obtained. Therefore, since the primary foam has already been foamed to a medium level, the secondary foaming can be performed smoothly, and a foaming time can be reduced to obtain a polyvinyl chloride resin-based foam which can improve productivity.

[Effects of the Invention] As described above in detail, according to the method of the present invention, after the primary foam is obtained, the primary foam is continuously heated and foamed to obtain a secondary foam, thereby obtaining a foaming time. And the productivity can be improved, and a highly reliable polyvinyl chloride resin-based foam free from defects such as tears can be obtained.

[Brief description of the drawings]

1 (A) to 1 (D) are explanatory views showing a method for producing a polyvinyl chloride resin-based foam according to the present invention in the order of steps. 1 ... mold, 2 ... press machine, 3 ... primary foam, 4 ...
... oven, 5 ... secondary foam (final foam).

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-B 32-7544 (JP, B1) “Polyvinyl Chloride-Its Basics and Applications”, edited by Kinki Chemical Association Vinyl Subcommittee, October 25, 1988 Published by Nikkan Kogyo Shimbun, page 492

Claims (1)

(57) [Claims] 1. To 100 parts by weight of a polyvinyl chloride resin, 15 to 100 parts by weight of a nitrile rubber, a foaming agent, a crosslinking agent, and a plasticizer are added and kneaded to form a mixture. Filling, heating and pressurizing with a press machine, further releasing the mold to obtain a primary foam, and then continuously heating and foaming this primary foam free to obtain a secondary foam, characterized by polychlorination. A method for producing a vinyl resin foam.