JPH08134422A - Self-adhesive fluororubber composition - Google Patents

Abstract

PURPOSE: To obtain a self-adhesive compsn. which is based on a fluororubber, is resistant to both heat and solvents, and exhibits excellent self-adhesive properties. CONSTITUTION: This compsn. contains 100 pts.wt. peroxide-cross-linkable fluororubber polymer, a catalytic amt. of a peroxide. and 30-200 pts.wt. peroxide- uncross-linkable fluororubber polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-based pressure-sensitive adhesive composition having excellent heat resistance and solvent resistance, which is used in a wide variety of applications including pressure-sensitive adhesive tapes, pressure-sensitive adhesive parts and pressure-sensitive jigs. It is possible.

[0002]

2. Description of the Related Art Generally, a rubber-based pressure-sensitive adhesive composition improves the tackiness of rubber by adding a tackifier.
Conventional rubber polymers and tackifiers have poor heat resistance, and there is a risk that additives such as tackifiers will bleed out and migrate to the adherend. For example, the heat resistance of a typical acrylic adhesive as a rubber-based adhesive composition is 180 ° C or less,
If the temperature exceeds 00 ° C, the adhesive strength will drop sharply, and if it exceeds 180 ° C, the polymer itself will undergo thermal decomposition, so there is a limit to use at high temperatures. Further, a general rubber-based pressure-sensitive adhesive composition is such that when dust or foreign matter is attached to the pressure-sensitive adhesive surface, the adhesive component is eluted and the adhesive strength is extremely reduced when it is wiped off with a solvent, etc. Adhesive strength may be lost if used in a place where Silicone-based pressure-sensitive adhesives are representative of heat-resistant pressure-sensitive adhesives, but these have excellent heat resistance up to around 200 ° C, and also have poor solvent resistance to toluene, etc. There is a limit, and if it exceeds 200 ° C, there is a drawback that cohesive failure tends to occur.

Fluorine rubber has excellent heat resistance, solvent resistance, chemical resistance, etc., but is inherently adhesive rubber, and is used in a compressed state in applications such as gaskets and sealing materials. Since the fluororubber sticks to the surface when it is disassembled during maintenance and inspection, which makes maintenance and inspection work difficult, there have been many studies on how to remove the tackiness of fluororubber. However, cross-linked fluororubber only shows tackiness when it is strongly compressed and left for a long time or when it is heated and compressed, and it does not show stable tackiness so that it can be used as a tackifier. It was common to add a starch syrup-type fluorine-containing additive with a small molecular weight, which is commercially available as a liquid fluororubber, in order to improve the Only less than one part can be added, and if more is added, foaming will occur during crosslinking and curing, so there is a limit to improving the adhesive strength by this method.

A fluororubber polymer which is not crosslinked has excellent tackiness but weak cohesive force and is problematic for use as an adhesive. Therefore, by adding fiberized polytetrafluoroethylene, the cohesive force of the fluororubber composition is improved. It has been proposed to improve the composition to give an adhesive composition (Japanese Patent Publication No. 61-4).
See No. 2955). However, in this method, since the fluororubber polymer is not crosslinked, it has the drawback that it will undergo cohesive failure at high temperatures above 200 ° C and lack flexibility at room temperature. Furthermore, it will be crosslinked for the purpose of improving the cohesive strength of this composition. If it is allowed, the problem remains that the adhesive strength will decrease.

However, there is no suitable tackifier for imparting tackiness to the cross-linked fluororubber polymer, and even if a tackifier for synthetic rubber is added, the compatibility is poor, and the heat resistance and solvent resistance are further improved. It becomes inferior. That is, the heat resistance of tackifiers is generally significantly inferior to that of fluororubber polymers, and similarly, there are very few tackifiers that also have good solvent resistance, so the liquid fluororubbers mentioned above are used as tackifiers. However, satisfactory adhesive properties have not been obtained.

[0006]

From such a situation,
The present invention was made to obtain an adhesive composition which is a fluororubber system and has excellent heat resistance and solvent resistance at 200 ° C. or higher and which exhibits excellent adhesiveness.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a peroxide-uncrosslinkable fluororubber polymer is added to a peroxide-crosslinking fluororubber composition. According to the present invention, it was found that a fluororubber-based pressure-sensitive adhesive composition exhibiting excellent adhesiveness having both heat resistance and solvent resistance can be obtained. That is, the fluororubber-based pressure-sensitive adhesive composition of the present invention solves the above-mentioned problems. 1) 100 parts by weight of a fluororubber polymer capable of crosslinking with peroxide. 2) catalyst amount of peroxide. It contains 30 to 200 parts by weight of a possible fluororubber polymer.

The present invention will be described in more detail below. The peroxide-crosslinkable fluororubber polymer of component 1 used in the present invention is highly fluorinated and has in its molecule a peroxide-reactive group such as an unsaturated group such as a double bond.
It is an elastic polymer in which iodine or bromine is introduced. In this case, those containing 0.001 to 10% by weight of the peroxide reactive group are preferable. If it is less than 0.001% by weight, sufficient crosslinking may not be obtained, and if it exceeds 10% by weight, rubber elasticity may be impaired. Specific examples of such fluororubber polymers include vinylidene fluoride and hexafluoropropene, pentafluoropropene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro. An elastic copolymer with one or more kinds such as (propyl vinyl ether), into which a double bond, iodine or bromine is introduced, can be mentioned.
Of these, vinylidene fluoride-hexafluoropropene binary elastic copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropene ternary elastic copolymer, etc. are particularly preferably used as a basic skeleton. Is mentioned. As such a peroxide-crosslinkable fluororubber polymer, a commercially available one for peroxide crosslinking can be used.

The non-peroxide cross-linkable fluororubber polymer of the component 3 is a component which imparts tackiness when the composition of the present invention is cross-linked and has no peroxide-reactive group. However, the molecular structure is basically the same as that of Component 1 described above. The component 3 may be used alone or in combination of two or more kinds. Further, a liquid fluororubber having a small molecular weight or a solid type fluororubber having a large molecular weight may be used. However, when the liquid fluororubber is used alone, foaming may occur. It is preferable to use it in combination with a type of fluororubber. The blending amount of the non-peroxide crosslinkable fluororubber polymer of the component 3 is 30 with respect to 100 parts of the peroxide crosslinkable fluororubber polymer of the component 1 (part by weight, the same hereinafter).
It is up to 200 parts, because if it is less than 30 parts, the tackiness is weak, and if it is more than 200 parts, foaming tends to occur during crosslinking. It is more preferably 50 to 150 parts. Commercially available fluororubber polymers that cannot be cross-linked with peroxide can be used. The two kinds of fluororubber polymers of component 1 and component 3 having different cross-linking properties can be blended together with other components at the same time. However, if only the fluororubber polymer is blended in advance and the other components are added, the kneading work can be performed. It can be done efficiently.

Organic peroxides can be used as the component 2 peroxide. Specifically, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, 2,5-di-methyl-
2,5-di-t-butylperoxyhexane, 2,4-
Dichlorobenzoyl peroxide, 1,1-bis (t
-Butylperoxy) 3,3,5-trimethylchlorohexane, 1,1-bis (t-butylperoxy) chlorohexane, cyclohexanone peroxide, methyl ethyl ketone peroxide, 1,6-bis (t-butylperoxycarbonyl) (Oxy) hexane, lauroyl peroxide and the like are exemplified. The amount of the peroxide to be blended may be a catalytic amount, but it is 1 to 20 parts, especially 2 to 100 parts with respect to 100 parts of the peroxide-crosslinkable fluororubber polymer of the component 1.
It is preferably 10 parts. If it is less than 1 part, the crosslinking will be insufficient, and if it exceeds 20 parts, it will be difficult to knead it with the fluororubber polymer, and the mechanical strength after crosslinking may decrease, and it is also economically disadvantageous.

Further, it is preferable to add a crosslinking aid to the composition of the present invention. Examples of such a crosslinking aid include diallyl ether of glycerin, triallyl phosphoric acid, diallyl adipate, diallyl melamine, triallyl isocyanurate, triallyl cyanurate and the like. For the same reason as in the case of the above-mentioned peroxide, the amount of the crosslinking aid compounded is 1 to 20 parts, especially 2 to 10 parts, relative to 100 parts of the peroxide-crosslinkable fluororubber polymer of the component 1. Is preferred.

An acid acceptor is preferably added to the composition of the present invention. A metal compound may be added as the acid acceptor, and specific examples thereof include magnesium oxide, calcium oxide, lead oxide, calcium hydroxide, barium stearate, sodium stearate and the like. These compounds can be used alone or in combination of two or more kinds. The compounding amount of the acid acceptor is preferably 1 to 20 parts with respect to 100 parts of the peroxide-crosslinkable fluororubber polymer of the component 1.

The composition of the present invention may further contain a filler, a colorant and the like, if necessary. Examples of the filler include silica, carbon black, alumina, red iron oxide, clay, calcium carbonate, titanium oxide, polytetrafluoroethylene powder, various conductive fillers, various heat-dissipative fillers, and the like, among them silica from the viewpoint of reinforcement, Carbon black is preferable, and MT carbon black is particularly preferable. It is also possible to use those obtained by treating these powders with a silane-based or titanate-based surface treatment agent for the purpose of dispersing, reinforcing and improving the wettability. The blending amount is preferably 100 parts or less, particularly 50 parts or less with respect to 100 parts of the peroxide-crosslinkable fluororubber polymer of the component 1, and when 100 parts or more are added, the flexibility of the composition may decrease.

In order to produce the fluororubber adhesive composition of the present invention, the above-mentioned components are kneaded, but it is preferable that the above components are sufficiently uniformly dispersed in the fluororubber adhesive composition by kneading. It is desirable to use a two-roll rubber roll, a pressure kneader, a kneader, a Banbury mixer, etc., which are used for kneading, and perform kneading suitable for each compounding. The fluororubber-based pressure-sensitive adhesive composition obtained as described above can be processed in accordance with known fluororubber composition processing methods, such as tape processing by extrusion molding, sheet processing by calendar molding, and molding by a mold. Processing and the like can be performed, and adhesion to different materials can be easily performed by using a known fluororubber primer. The molded product obtained has a viscosity of 150 to 2 to stabilize its adhesiveness.
Secondary cross-linking is preferably carried out by heating at a temperature of 50 ° C. for 1 to 24 hours, and stable adhesive force can be obtained even in a high temperature environment.

[0015]

【Example】

Examples 1 to 3 A fluororubber composition having the composition shown in Table 1 which was kneaded with a rubber roll was molded at 170 ° C for 15 minutes, and further post-cured at 230 ° C for 24 hours to perform physical properties according to JIS-K-6301. And JIS-
The adhesive strength was measured according to Z-0237. Physical property measurement sample
It is a 150 x 200 x 2 mm rubber sheet. For the adhesive strength measurement sample, a fluororubber primer (FC5150, a product name of Sumitomo 3M Co., Ltd.) was applied to a 100 x 100 x 0.5 mm aluminum plate, and aluminum and rubber were integrally molded to a rubber thickness of 0.5 mm. However, at this time, a release agent was not used on the adhesive surface, and a PFA film was used so that a release layer could not be formed on the surface, and the treatment was performed under the above conditions. Then on the adhesive side of this thing
After a polyimide film having a thickness of 50 μm and a width of 30 mm was applied with a load of 500 g, the polyimide film was measured at room temperature and 200 ° C. at a 180 ° angle with a pulling speed of 300 mm / min to measure the load required for peeling. The results are also shown in Table 1. In all cases, it was found that the adhesive strength was good at room temperature and the adhesive strength was good even at 200 ° C. Furthermore, the adhesive surface of this product was wiped with toluene and methanol to remove dust and dirt adhering to it, but it was found that the adhesive force did not change and was stable to the solvent. Next
After being left at a temperature of 250 ° C. for 1 hour and cooled, a polyimide film was similarly laminated and the adhesive strength was measured, but no decrease in the adhesive strength was observed.

Comparative Example 1 When a sample similar to the example was prepared with the general composition of peroxide crosslinking shown in Table 1 and evaluated, it was found that the adhesive strength was considerably weaker than that of the example as shown in Table 1. It could be confirmed. Comparative Example 2 As shown in Table 1, when up to 300 parts of a fluororubber that did not undergo peroxide crosslinking was added, foaming occurred during molding and evaluation was impossible. Comparative Example 3 As shown in Table 1, a peroxide-crosslinkable fluororubber was added to the fluororubber composition instead of the tackifier, but it was found that the tackiness was low and not practical as compared with the examples. . Comparative Example 4 As shown in Table 1, when only 10 parts of fluororubber that was not cross-linked with peroxide was added, it was found that the adhesive force was considerably low as compared with the examples.

[0017]

[Table 1]

The materials used in Examples and Comparative Examples are as follows. Peroxide-crosslinkable fluororubber 1: Daier G801 ...
Daikin Co., Ltd. Trade name Peroxide crosslinkable fluororubber 2: Florel FC2260
… Sumitomo 3M Company's trade name Peroxide non-crosslinkable fluororubber 3: Daier G201…
Daikin Co., Ltd. Trade name Peroxide Non-crosslinkable fluororubber 4: Florel FC21
45… Sumitomo 3M product name peroxide crosslinking agent: C-8A… Shin-Etsu Chemical Co., Ltd. product name Cross-linking auxiliary agent: Taik… Nippon Kasei Co., Ltd. product name Calcium hydroxide (acid acceptor): Caldec… Omi Chemical company trade name MT carbon (filler): manufactured by Harbor Company

[0019]

EFFECTS OF THE INVENTION According to the present invention, an adhesive composition having excellent heat resistance and adhesive strength even at 200 ° C. and having excellent solvent resistance and chemical resistance was obtained. The composition of the present invention has excellent composition strength, has little decrease in adhesive strength even after cleaning the adhesive surface, and can be reused, and does not transfer an adhesive component.

Claims (2)

[Claims] 1. A fluororubber comprising 1) 100 parts by weight of a peroxide-crosslinkable fluororubber polymer, 2) a catalyst amount of peroxide, and 3) 30 to 200 parts by weight of a peroxide-noncrosslinkable fluororubber polymer. -Based adhesive composition. 2. The fluororubber adhesive composition according to claim 1, wherein the peroxide-uncrosslinkable fluororubber polymer is a copolymer of vinylidene fluoride and hexafluoropropylene.