JPH09279703A - Shaped sealant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant usable for a long period by adding satisfactorily compatible and hardly compatible swelling polymers to a shaped sealant formed of a rubber composition foamed body to keep the closely adhered state even when a stress modulation or creep phenomenon is caused. SOLUTION: A joint material for bath unit or kitchen unit, a sealant for tube fitting, and a packing or gasket used for building waterproof material is formed by kneading a satisfactorily compatible swelling polymer and a hardly compatible swelling polymer to a rubber followed by foaming by heating. It is swollen by the water penetrated in use to increase the sealing surface pressure, and the hardly compatible swelling polymer is bloomed to the sealant surface to seal the critical surface with the sealing surface, whereby the penetration of water is minimized. Thus, the closely adhered state of the sealing critical surface can be sufficiently kept even when a stress moderating phenomenon or creep phenomenon is caused in its long-term use, and satisfactory sealing property can be ensured over a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standard seal material composed of a water-swellable foamed molded article.

[0002]

2. Description of the Related Art It has been known to use a water-swellable rubber foam as a seal material.
-65410, JP-A-6-25380, JP-A-7-109369, JP-B-5-48775, JP-B-7-68396, etc.). As is well known, there are continuous foam and closed foam in the foam structure, and even the same substance may become open cells or closed cells depending on the foaming method and the expansion ratio, but usually both are mixed (open cell Hereinafter, a mixed foam of closed cells and closed cells may be referred to as a semi-open / semi-independent foam). In the above-mentioned water-swellable foam sealing material, the water-swellable polymer in which water that permeates through continuous cells is contained in the foam film of the foam.
It is necessary to have open cells in order to swell the water absorbing and swelling polymer by contacting with.

[0003]

In the above-described water-swellable foam seal material, it is required that when it comes into contact with water, a predetermined seal surface pressure is generated immediately by the swelling. However, since the seal material is always placed in a compressive stress state, as is known in stress relaxation and creep phenomenon, cross-linking breakage or main chain breakage occurs, and compression occurs over time. The stress is reduced, and it is inevitable that the seal surface pressure is considerably lowered after a long period of time, and even with the water-swellable foam seal material, after the seal surface pressure is lowered, a sudden contact occurs. A satisfactory seal against water is difficult.

The object of the present invention is to provide a standard seal material made of a water-swellable foamed rubber which swells upon contact with water to generate a seal surface pressure, even if stress relaxation or creep phenomenon occurs. An object of the present invention is to provide a standard seal material capable of ensuring good sealability.

[0005]

A typical sealing material according to the present invention comprises a foamed structure of a rubber composition having closed cells and open cells, and is a water-swellable polymer having good compatibility with the rubber composition. And a water-swellable polymer which is hardly compatible with the above are added.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The molded seal material according to the present invention is a natural rubber or a synthetic rubber (chloroprene rubber, ethylene.
Propylene / terpolymer, etc.), a vulcanizing agent, a foaming agent, a filler, etc., as well as a water-swellable polymer which is well compatible with 100 parts of synthetic rubber and a poorly water-swellable polymer-30 to 30 parts.
60 parts of the mixture was kneaded with a Banbury mixer, mixin roll, etc., and the kneaded material was molded into a sheet, which was vulcanized / foamed by heating and cooled to form a foam mainly composed of closed cells ( The ratio of closed cells is about 50% or more), and further, a part of the bubbles is broken by pressurization to obtain a semi-continuous / semi-independent foam.
Further, if necessary, the semi-continuous / semi-independent form can be manufactured by cutting into a predetermined size and a predetermined shape. In this case, a mixin sphere or the like can be used for breaking the bubbles by applying pressure.

The shaped seal material according to the present invention is particularly suitable as a water blocking seal material, for example, a joint material for a bath unit, a kitchen unit, etc., and a seal for a pipe joint of a water supply pipe or a drain pipe. It can be used as a roof material, a rear combination lamp seal for automobiles, a waterproof material for houses, etc.

The regular seal material according to the present invention is advantageous for filling a complex gap to stop water, and in order to facilitate the filling work, the seal space is more suitable than the gap space. It is preferable to make the cross-sectional area of the seal material slightly larger and to fill the seal material with a compression rate as low as possible.

In the regular seal material of the present invention, the sparingly compatible water-swelling polymer is easily separated from the base rubber and is easily bloomed on the surface of the seal material. Under contact with the water, the water-swellable polymer which has been swelled by the water is swollen by water penetrating the interface between the seal material and the surface to be sealed, and the interface Is sealed. On the other hand, in the water-swellable polymer having good compatibility,
It does not substantially bloom and remains stably dispersed in the rubber and is swollen by water that permeates through continuous foaming.
The speed of swelling is slower than the speed of swelling at the seal interface of the bloomed water-swellable polymer. Therefore, the seal effect against sudden contact with water largely depends on the compatible water absorbing and swelling polymer.

In the shaped seal material according to the present invention, during use, the water-swellable polymer having good compatibility, which is held in the rubber in a uniformly dispersed state, swells due to moisture absorption, and the uniform swelling of the rubber occurs. Since the seal surface pressure is increased due to the increase in volume, even if a stress relaxation phenomenon or a creep phenomenon occurs during long-term use, the adhesion state of the seal interface can be sufficiently maintained, and The excellent sealing property is exhibited in cooperation with the water-swelling polymer having poor compatibility and water absorption. On the other hand, in the case of only the poorly compatible water-swelling polymer, the water-swelling polymer was bloomed and the rubber itself was not expanded, and the seal interface in a loose contact state was bloomed. Since the sealant must be swelled only by the water-swellable polymer, the excellent sealability of the present invention cannot be expected. This can be confirmed by comparing the following examples and comparative examples.

[0011]

EXAMPLES [Examples] Polyacrylic acid-based polymers are used as water-insoluble swelling polymers that are incompatible with ethylene / propylene-terpolymer, and isobutylene-maleic anhydride alternating co-polymers are used as water-swelling polymers that are well-compatible. The composition having the following composition (parts by weight) using the coalescence was kneaded with mixin-gall, and the kneaded material was vulcanized / foamed by heating in an oven at 150 ° C. for 30 minutes. It was taken out from the container, cooled, and part of the bubbles was broken by pressurization to obtain a semi-german semi-continuous foam. Blending ethylene / propylene / terpolymer 100 parts Zinc white 5 parts Stearic acid 3 parts Carbon black 5 parts Cray 75 parts Process oil 40 parts Sulfur 1.5 parts Butylthiourea 2.0 parts Blowing agent (azodicarbonamide ) 20 parts Foaming aid 14 parts (Urea-based foaming aid, product name Cellpaste K-5 manufactured by Eiwa Kasei Co., Ltd.) Incompatible water-swelling polymer 30 parts (Polyacrylate-based polymer, Sanyo Chemical Co., Ltd.) Trade name Sunfresh ST-500MPS) Good compatibility Water-swelling polymer 30 parts (isobutylene-maleic anhydride alternating copolymer, trade name KI gel 201K-F2 manufactured by Kuraray Co., Ltd.)

[Comparative Example 1] The same as Example 1 except that the addition of the hardly miscible water-swelling polymer and the good miscible water-swelling polymer was omitted. [Comparative Example 2] The same as Example 1 except that the addition of the hardly miscible water-absorption polymer was omitted. [Comparative Example 3] The same as Example 1 except that the addition of the well-compatible water-absorption polymer with good compatibility was omitted.

Each of the products of Examples and Comparative Examples described above was processed into a string having a square cross section with a thickness of 10 mm and a width of 10 mm, and each of these samples A was processed as shown in FIGS. 1 (a) and 1 (b). As shown in the [Roll cross-sectional view in FIG. 1 (a)], the U-shaped sample was sandwiched between the acrylic plates 1 and 1, and the compressibility in the thickness direction of the sample A was 30%, 50%, 70%. % And 9
The space was adjusted with spacers 2 and 2 so as to be 0%, and the acrylic plates 1 and 1 were fastened with bolts and nuts 3, ....
After the bolts were fastened, water 4 was put into the U-shape of sample A at a water head h of 100 mm.
In Table 1, ◯ indicates no water leakage, and x indicates water leakage occurrence.

[0014]

Next, for each of the example 3 and the comparative example product 3, at a compression rate of 30%, a product clamped between the acrylic plates by bolting was used in the same manner as in FIG. After a long period of time, a high compression stress is generated in the standard seal material of each sample to forcefully deform it beyond the elastic limit, and it is taken out of the oven to reduce the contact surface pressure similar to stress relaxation. Raised. After that, similarly to the above, when water 4 was put into the U-shape of the sample A at a water head h = 100 mm and the presence or absence of water leakage was examined, no water leakage was observed in the example, whereas Water leakage was observed in Comparative Example 3.

As is clear from Table 1, in the case of the seal using only the contact surface pressure (Comparative Example 1), in order to perform the sealing, the contact surface pressure with a compression rate of 90% is required ( In Comparative Example 1) and Comparative Example 3 (the one in which the poorly compatible water-swellable polymer was added), the water-swelling action of the water-swellable polymer was obtained even at the contact surface pressure (initial contact surface pressure) at a compressibility of 30%. Sealing is possible due to the increase of the contact surface pressure due to, but under the occurrence of the stress relaxation phenomenon, the initial contact surface pressure decreases substantially, and the water-swelling action of the water-swelling polymer causes the sealing. The contact surface pressure required for the tool cannot be obtained.

On the other hand, a poorly compatible water-swellable polymer
In the seal material according to the present invention to which both the water-swellable polymer and the water-swellable polymer having good compatibility are added, even if the stress relaxation phenomenon occurs, the water-swellable polymer is uniformly dispersed and held in the rubber, and the rubber is In order to expand uniformly, the decrease in contact surface pressure due to the stress relaxation phenomenon is offset by the increase in contact surface pressure due to the uniform expansion of the rubber, and a good compatible water-absorbing swelling polymer and a poorly compatible water-absorbing swelling polymer are obtained. A good seal is guaranteed by the cooperation of.

[0018]

INDUSTRIAL APPLICABILITY In the standard seal material composed of the foamed structure of the rubber composition according to the present invention, even if stress relaxation or creep phenomenon occurs due to cross-linking breakage or main chain breakage, a water-swelling polymer. It is possible to satisfactorily carry out the seal due to the water absorption and swelling action, and to guarantee a stable seal for a long period of time.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a test method for testing the water-stopping property of a regular seal material according to the present invention, and FIG.
The sample set state is shown, and (b) in FIG. 1 is (a) in FIG.
3 is a cross-sectional view taken along the line.

[Explanation of symbols]

 A sample 1 acrylic plate 2 spacer 3 bolt / nut 4 water

Claims (1)

[Claims] 1. A rubber composition foam structure having closed cells and open cells, wherein a water-swellable polymer having good compatibility and a water-swellable polymer having poor compatibility are added to the rubber composition. A standard seal material characterized by the following.