JPH0489839A - Vulcanization and bonding of rubber - Google Patents

Abstract

PURPOSE:To produce a bonded product improved in bonding strength and appearance by joining two specified rubbers and covulcanizing them. CONSTITUTION:Ethylene is radical-polymerized with a saturated carboxylic acid vinyl ester in a high-pressure gas phase to obtain an ethylene/saturated carboxylic acid vinyl ester copolymer of a number-average molecular weight of 1000-20000 and an ethylene content of 1-90wt.%. This copolymer is saponified to obtain a saponificate of the above copolymer with a saponification degree of 30-100%. 100 pts.wt. this saponificate and 20-1000 pts.wt. alkylene oxide are subjected to an addition reaction to obtain an ethylene/saturated carboxylic acid vinyl ester copolymer saponificate/alkylene oxide adduct (a). A vulcanized or unvulcanized rubber (b) is mixed with component (a) to obtain a vulcanized or unvulcanized rubber (A) containing component (a). Separately, an unvulcanized rubber (c) is optionally mixed with component (a) to obtain an unvulcanized rubber (B) containing or not containing component (a). Component A and component B are joined and covulcanized.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a rubber vulcanization bonding method. More specifically, the present invention relates to a comb vulcanization bonding method that can provide a vulcanized rubber having excellent adhesive strength and excellent appearance.

The vulcanized rubber obtained by this method can be used, for example, in automobile interiors,
It can be especially used in applications that require excellent adhesive strength such as exterior rubber parts, rubber parts for helmets, rubber hoses, etc., and especially in applications that require excellent appearance.

<Prior art> Generally, vulcanized rubber changes over time (rubber chemicals such as vulcanization accelerators, anti-aging agents, sulfur, inorganic reinforcing agents, etc.)
It is known that a so-called bloom phenomenon occurs in which particles migrate and precipitate, causing the surface to become powdery or have a characteristic bluish tinge, resulting in a deterioration in appearance.

This problem not only deteriorates the appearance, but also often causes an adverse effect on the adhesion of rubber.

In other words, we are trying to vulcanize rubber and use it as a molded product. There is a method of joining the manufactured vulcanized rubber parts with adhesive, and another method is to sandwich the unvulcanized rubber between the vulcanized rubber parts and then vulcanize the parts with the unvulcanized rubber part at the center (second vulcanization). A vulcanization adhesion method is known.

Although the method of bonding with adhesive is relatively simple, it may be difficult to obtain sufficient adhesive strength due to the type of rubber, abnormal softening of the adhesive layer due to the difference in the materials of the rubber and adhesive, or Due to its hardness, stress concentration during bending causes problems such as breakage and deformation.

On the other hand, since the vulcanization bonding method does not use adhesives (these problems are solved, there is a fatal problem in that the precipitation of rubber additives due to the plume phenomenon C2 reduces the adhesive strength). (If this vulcanized rubber is adhered after being stored for a long period of time, a significant decrease in adhesive strength will be observed.

Therefore, as a method of suppressing the precipitation of bloom substances that cause a decrease in vulcanization adhesive strength, for example, a method of adding a non-reactive phenol formaldehyde resin or polyethylene glycol is known. (Refer to Japanese Patent Publication No. 59-15345.) <Problems to be Solved by the Invention> However, although such conventional methods have a certain degree of delay effect on the progress of the bloom phenomenon, they are not sufficient for a long period of time (ζ). This was not satisfactory in terms of suppressing the occurrence of vulcanization, and no improvement effect was observed in vulcanization adhesive strength.

In view of the current situation, the inventors of the present invention have proposed that the adhesive strength of the vulcanized adhesive is greatly improved as the bloom phenomenon does not occur even after being exposed to heat for a long period of time, and as a result, the excellent appearance can be maintained for a long period of time (without breaking). The present invention was achieved after extensive research with the main purpose of obtaining vulcanized rubber.

<Means for Solving the Problem> That is, the present invention provides a vulcanized or unvulcanized comb containing a fullylene oxide adduct of a saponified ethylene-saturated carboxylic acid vinyl ester copolymer, and an ethylene-saturated carboxylic acid vinyl ester copolymer. A rubber vulcanization adhesion method characterized by connecting uncured rubbers containing or not containing an alkylene oxide adduct of a saponified ester copolymer and covulcanizing them.

The details will be explained below.

In the present invention (2) Vulcanized rubber is a well-known term in the industry, and in order to make raw rubber as a main raw material into a practical (and excellent) rubber (2) cross-linking a composition to which sulfur and other compounding agents are added. It has a three-dimensional network structure with improved elasticity and strength.

- Boat fishing (this is done by adding sulfur and heating (this method creates a cross-linked structure via sulfur), but instead of adding sulfur, adding peroxide and heating (such as cross-linking) In this industry, vulcanization is sometimes used as a synonym for vulcanization in a broad sense, and in the present invention, vulcanization refers to three-dimensional crosslinking of these rubbers.

Therefore, unvulcanized rubber refers to a rubber composition mixed with sulfur, etc. and kneaded before vulcanization.

As the rubber used in the present invention, a wide variety of natural and synthetic rubbers can be used without limitation, but it is particularly suitable for synthetic rubbers, such as ethylene-a Examples include -olefin copolymer rubber, styrene-butanene copolymer rubber (SBR), chlorobreno rubber (CR), nitrile rubber (NBR), and isoprene-isobutane copolymer rubber (IIR).

Here, the ethylene-a-olefin copolymer rubber refers to a copolymer (EPM) consisting of ethylene and one or more types of a-olefins, or a copolymer (EPM) consisting of ethylene, one or more types of a-olefins, and one or more types of non-conjugated diene. A copolymer (EP
DM), examples of the a-olefin include furopyreno-1-butene, 1-penote/, 1-hexene, etc., and examples of the non-conjugated diene include dinochlorobentadieno (DC
PD), Ethyriteno Norborui No (ENB), 1
．． Examples include 4-hexanoeno, methyltetrahydride, and methylnorpol.

In the present invention, these rubbers are co-vulcanized by putting unvulcanized rubber between the vulcanized rubber and the vulcanized rubber. (However, since vulcanization may also progress on the vulcanized rubber side, it is expressed as co-vulcanization here.) Although it is used primarily for adhesion, the present invention does not necessarily apply to vulcanized rubber. Adhesion of vulcanized rubber to vulcanized rubber (this includes, but is not limited to, co-vulcanized adhesion of unvulcanized rubber to unvulcanized rubber, and the two types of rubber to be bonded do not necessarily have to be the same). do not have.

The ethylene-saturated carboxylic acid vinyl ester copolymer used in the present invention can be produced by a known method, for example, high-pressure gas phase radical polymerization.

As the saturated carboxylic acid vinyl ester, a wide variety of compounds can be used without particular limitation, but specific examples include vinyl acetate, vinyl propionate, vinyl butyrate, etc. Among them, vinyl acetate Vinyl is particularly preferred.

Also, copolymerization of ethylene and saturated carboxylic acid vinyl ester (at this time, a small amount of unsaturated carboxylic acid alkyl ester, such as methyl acrylate or methyl methacrylate, etc., may be copolymerized to form a multicomponent copolymer. included.

The ethylene content and number average molecular weight of the ethylene-saturated carboxylic acid vinyl ester copolymer (2) are not particularly limited, but are 1 to 90% by weight and 1000 to 2000% by weight, respectively.
A range of 0 is particularly preferred.

The fullylene oxide adduct of the saponified ethylene saturated carboxylic acid vinyl ester copolymer used in the present invention (hereinafter sometimes simply referred to as "adduct j") refers to a copolymer of ethylene and saturated carboxylic acid vinyl ester. It is obtained by adding alkylene oxide to a saponified polymer.

A wide variety of alkyleph oxides can be used without particular limitation, but specific examples include ethylene oxide, propylene oxide, butylene oxide, etc. Species or two or more species may be block or random (di-added), especially ethylene oxide (
This is preferable.

There is no particular limit to the saponification rate of the saponified ethylene-saturated carboxylic acid vinyl ester copolymer, but it is 30%
The range of ~100% is particularly preferred, and more preferably 50~100%
The range is more preferable.

Ethylene: / - Saturated carboxylic acid vinyl ester copolymer saponified product (20 to 1,000 parts by weight of the saponified product (20 to 1,000 parts by weight), although there is no limit) Particularly preferred is a range of .

The method for producing the adduct used in the present invention is not particularly limited, but it can be obtained, for example, as follows.

A saponified ethylene-saturated carboxylic acid vinyl ester copolymer is obtained by heating the mass ethylene-saturated carboxylic acid vinyl ester copolymer in alcohol in the presence of an alkali.

Next, the saponified product and arekylen oxide are heated and reacted in the presence of an alkali.

The adduct of the present invention is obtained from the reaction product thus obtained.

The present invention (2) Blending the additives used in the rubber with the rubber.
・Special (There is no restriction on this, and it may be added together with other rubber additives, but known bloom inhibitors such as non-reactive phenol formaldehyde resin or polyethylene glycol may also be used in combination.

The vulcanization adhesion method of the present invention (the rubber composition to which this is applied contains 05 to 10 parts by weight, preferably 1 to 5 parts by weight, of the above-mentioned additive per 100 parts by weight of rubber, and further contains ( 2.Usually added vulcanization accelerators, anti-aging agents, and
A composition consisting of an inorganic reinforcing agent such as carbon blank, an organic softener called process oil, sulfur and other rubber additives is used, and it is either vulcanized or unvulcanized. Either or both of the rubbers to be covulcanized and bonded contain the above-mentioned additive.

When the amount of the adduct is less than 0.5 parts by weight (in this case, the effect of suppressing the occurrence of bloom by using two vulcanized rubbers obtained according to the present invention is not sufficient, the improvement in the 7JD sulfur adhesive strength is insufficient, and the amount of the adduct is less than 0.5 parts by weight. If the amount exceeds 10 parts by weight, the effect of suppressing bloom generation is maintained, but practical problems such as a decrease in the strength of the vulcanized rubber occur, so it is not so preferable.

<Examples> The present invention will be specifically described below (Reference Examples, Examples, and Comparative Examples), but the present invention is not specifically limited to these examples.

Reference Example-1 In a stainless steel autoclave with a capacity of 700 L equipped with a stirrer, a gas phase distillation line, and a feed line, an ethylene-vinyl acetate copolymer 160Kr with a vinyl acetate content of 31% by weight and a number average molecular weight of 1800, Methyl alcohol 320K9, and sodium hydroxide 0.96Kf
was charged, and while opening the gas phase distillation line, the temperature was increased to 65.
The reaction was allowed to proceed for 2 hours at ℃ while stirring with DO heat.

Then, the temperature was raised to 142°C over 1 hour.
All volatile components were driven out of the system.

The resulting saponified product had a melting point of 83° C., was waxy, and had a saponification rate of 90%.

Subsequently, 0.27 Kp of potassium hydroxide was added and the temperature was lowered to 1.
80'Ci was heated up and ethylene oxide was added to the pressure of 2 to 9/d. Addition reaction of ethylene oxide (confirm the pressure drop, then add 2 ethylene oxide)
Ethylene oxide was fed intermittently to keep the pressure at Kp/i, and a total of 272 Kp of ethylene oxide was charged over 1 hour.

When the pressure was reduced to 0.4 Kq/e++l, the temperature was lowered by 100°C and the product was taken out.
8 kg of adduct was obtained, the melting point of which was a 5-do-C1 hydroxyl value of 110 KOH/f. The amount of the adduct ethylene oxide added was 100 parts by weight of the saponified product (200 parts by weight per 2 parts by weight).

Example-1 Column (A) of Table-1 (The formulation shown here was kneaded in a Buffbury mixer at a temperature of 70 to 130°C for 4 minutes.

Next (After cooling the mixed wire to room temperature, add the formulation shown in Table 1 (B) at a temperature of 40 to 60°C using an oven roll, and make an unvulcanized rubber with a thickness of about 25 mm. Obtained.

Divide the unvulcanized rubber thus obtained into two halves, and use a heat press to separate one half! ll150III11.
Vulcanization was performed at 160° C. for 10 minutes in a mold having a width of 150 mm and a thickness of 2 mm to obtain four pieces of vulcanized rubber.

Cut the obtained vulcanized rubber notebook in half, place it on one side of a formwork of 150 mm length, 150 mm width, and 2 wm thickness.Put the above unvulcanized rubber into the remaining half of the empty frame and connect. Then, co-vulcanization bonding was carried out at 160° C. for 10 minutes using a hot press in the same manner as described above.

Note that in this co-vulcanized adhesive rubber, streaks were observed at the connection portion between the original vulcanized rubber and the unvulcanized rubber.

The obtained co-vulcanized adhesive rubber was allowed to stand at room temperature for a day and night, and then JIS
In the K-6301i method, the connecting part between the original vulcanized rubber and the unvulcanized rubber is streaked (the remaining part is placed in the longitudinal direction of the test piece (at right angles to it), and the remaining part is placed in the center of the test piece ( The adhesive strength was measured by punching out with a dumbbell and performing a tensile test.

In addition, for reference purposes, in order to determine the strength of the vulcanized rubber band that was not bonded, a tensile test was conducted (same as above) to measure the strength.

Furthermore, in order to find out the relationship between the number of days the vulcanized rubber notebook was left and the adhesive strength, we cut the vulcanized rubber notebook in half and stored it at room temperature. After connecting with rubber, co-vulcanization bonding was performed, and the adhesive strength of the dumbbell test piece was measured.

When the test pieces co-vulcanized and bonded in this manner were subjected to a tensile test, all of them were cut at the joint between the vulcanized rubber and the unvulcanized rubber.

The state of bloom was also observed by leaving the original vulcanized rubber notebook at room temperature and observing its appearance. The above results are shown in Table-2.

Comparative example-1 Example-1 (herein, reference example-1 shown in Table-1, column
The procedure was carried out in the same manner as in Example 1 except that no synthetic material was added, and the results shown in Table 3 were obtained.

Comparative example-2 Example-1 (Table-1 person column (Reference example-1 shown here)
Synthetic product (in return, 1 part of polyethylene glycol: 4000 manufactured by Sanyo Chemical Co., Ltd. and Takki Roll #101 manufactured by Taoka Chemical Co., Ltd.
(Non-reactive phenol-formaldehyde resin) The same procedure as in Example 1 was carried out twice, except that 1 part of non-reactive phenol-formaldehyde resin was added.
A result of 4 was obtained.

Example-2 Table-5(A) column (The formulation shown was
The mixture was kneaded with a trowel for 4 minutes at a temperature of 70 to 130°C.

Next (After cooling the kneaded material to room temperature, add the formulation shown in column Q of Table 5 (B) at a temperature of 40 to 60 ° C using an oven roll, and add the unvulcanized material to a thickness of about 2.5 mm. Got the rubber.

The unvulcanized rubber thus obtained was divided into halves and covulcanized and bonded in the same manner as in Example 1 (straightened and covulcanized), and the strength was measured by a tensile test. The results are shown in Table 6.

Comparative example-3 Example-2 (Reference example-1 shown here Table-5 person column)
Everything was the same as Example 2 except that no synthetic material was added (two tests were carried out, and the results shown in Table 7 were obtained).

Comparative Example-4 Example-2 (Table 5(A) column (Reference example-1 shown here) In contrast, 25 parts of polyethylene glycol 24000 manufactured by Sanyo Chemical Co., Ltd. and Takkiroll S manufactured by Taoka Chemical Co., Ltd.
101 (non-reactive phenol-formaldehyde resin) 25 parts was added, but everything was the same as in Example-2 (
The test was carried out twice and the results shown in Table 8 were obtained.

<Effects of the Present Invention> As described above, the rubber vulcanization adhesion method of the present invention includes a vulcanized or unvulcanized rubber containing an alkylene oxide adduct of a saponified ethylene-saturated carboxylic acid vinyl ester copolymer; Connecting unvulcanized rubber containing or not containing an alkylene oxide adduct of a saponified ethylene-saturated carboxylic acid vinyl ester copolymer,
The vulcanization bonding method has great industrial value because it can significantly improve the conventional blooming method, which tends to reduce bonding strength and extremely limits the bonding period.

Furthermore, the vulcanization adhesion method of the present invention has extremely deep significance as it can significantly improve the conventional adhesive strength level for applications that are difficult to handle with a single rubber molded product.

Claims (6)

[Claims] (1) Vulcanized or unvulcanized rubber containing an alkylene oxide adduct of a saponified ethylene-saturated carboxylic acid vinyl ester copolymer and an alkylene oxide adduct of a saponified ethylene-saturated carboxylic acid vinyl ester copolymer. A rubber vulcanization adhesion method characterized by connecting unvulcanized rubber containing or not containing it and co-vulcanizing it. (2) The rubber vulcanization adhesion method according to claim (1), wherein the rubber is an ethylene-α-olefin copolymer rubber. (3) The rubber vulcanization bonding method according to claim (1), wherein the rubber is styrene-butadiene copolymer rubber, chloroprene rubber, nitrile rubber, or isoprene-isobutylene copolymer rubber. (4) The alkylene oxide adduct of the saponified ethylene-saturated carboxylic acid vinyl ester copolymer has an ethylene unit content of 1 to 90% by weight and a number average molecular weight of 1,000.
-20,000, the saponification rate of which is 30 to 100%, and the amount of alkylene oxide added is 20 to 100 parts by weight of the saponified product. The rubber vulcanization adhesion method according to claim 1, wherein the amount is 1,000 parts by weight. (5) The method for vulcanizing and adhering rubber according to claim (1), wherein the saturated vinyl ester in the alkylene oxide adduct of the saponified ethylene-saturated carboxylic acid vinyl ester copolymer is vinyl acetate. (6) Claim in which the alkylene oxide in the alkylene oxide adduct of saponified ethylene-saturated carboxylic acid vinyl ester copolymer is ethylene oxide (
1) The rubber vulcanization adhesion method described above.