JPH0693249A - Silicone rubber gasket - Google Patents

Abstract

PURPOSE:To provide a gasket prepared by forming a cured film of a rubber composition composed of an ethylene-propylene-diene copolymer, etc., on the surface of a silicone rubber gasket body and excellent in non-staining properties. CONSTITUTION:The gasket is obtained by forming a cured film from a rubber composition composed of (A) 100 pts.wt. ethylene-propylene-diene copolymer (preferably 40 to 60wt.% propylene content), (B) preferably 0.1 to 50 pts.wt. organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to a silicon atom in one molecule, (C) platinum or a platinum compound and (D) a hydrolyzable organosilicon compound on the surface of a silicone rubber gasket body prepared by vulcanizing and molding a composition containing a diorganopolysiloxane, a reinforcing silica powder and a curing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contaminating silicone rubber gasket useful as a building gasket or the like.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As gaskets for construction, those made of rubber materials such as ethylene-propylene-diene rubber and chloroprene rubber are used, but these gaskets increase the service life of the building and the weather resistance of the gasket material. However, it has become impossible to meet the demand for improvement in creep resistance and the like.

For this reason, in recent years, silicone rubber gaskets have been widely used as building gaskets. This silicone rubber gasket is also used as a joint material for curtain wall construction methods and joint seals around aluminum sashes. However, when it is used as a zipper gasket for a long period of time, it has a drawback that surrounding concrete, stone plate, glass, etc. become dirty.

Further, in order to prevent the above-mentioned contamination due to the silicone rubber gasket, the contamination components in the vulcanized molded product of the silicone rubber composition are removed by carrying out post-curing for a long time, and the mobility in the raw material polymer is reduced. Measures such as removing molecular oligomers are taken. However, although these antifouling measures have some effects, they cannot be said to be sufficient, and there is a disadvantage that the cost is increased. Therefore, good improvement measures have been desired.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a silicone rubber gasket which has excellent weather resistance and creep resistance and is excellent in non-staining property on an adherend substrate.

[0006]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above object, the present inventor has found that (A) ethylene-propylene-diene copolymer (B) is formed on the surface of the silicone rubber gasket body. ) An organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule, (C) platinum or a platinum compound is excellent in forming a cured film of a rubber composition. It has been found to have characteristics.

That is, by forming a cured film of the rubber composition containing the ethylene-propylene-diene copolymer on the surface of the silicone rubber gasket body, the weather resistance and creep resistance are good, and the surrounding wall It was found that a silicone rubber gasket excellent in non-staining property can be obtained, which hardly stains adhered substrates such as materials, pillars, and glass materials. Furthermore, when the ethylene-propylene-diene copolymer composition is blended with a hydrolyzable organosilicon compound, it was found that the adhesiveness between the silicone rubber gasket body and the cured coating is further improved, and the present invention is realized. It was the eggplant.

The present invention will be described in more detail below. The silicone rubber gasket of the present invention comprises a silicone rubber gasket body and a cured coating of an ethylene-propylene-diene copolymer composition formed on the surface thereof.

Here, the silicone rubber molded body constituting the silicone rubber gasket body of the present invention is (a) diorganopolysiloxane, (b) reinforcing silica powder,
(C) It can be obtained by vulcanizing and molding a composition containing a curing agent.

In this case, as the diorganopolysiloxane of the component (a), the one represented by the following average composition formula (1) R ¹ _n SiO _{(4-n) / 2} (1) is used. it can.

In the above formula, R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl group such as a vinyl group, an allyl group, a butenyl group or a hexenyl group, From aryl groups such as phenyl group, tolyl group, etc., or chloromethyl group, trifluoropropyl group, cyanoethyl group, etc. in which some or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, cyano groups The same or different selected, preferably having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms
Is an unsubstituted or substituted monovalent hydrocarbon group. Further, n is a positive number of 1.98 to 2.02.

The organopolysiloxane of the above formula (1) is preferably one whose molecular chain ends are blocked with a trimethylsilyl group, a dimethylphenylsilyl group, a dimethylhydrogensilyl group, a trivinylsilyl group, etc. From the standpoint of preference, it is preferably a straight chain, but it may be one kind or a mixture of two or more kinds having different molecular structures.

Further, the above-mentioned organopolysiloxane has an average degree of polymerization of 100 to 100,000, particularly 5,000 to 2.
The viscosity at 25 ° C. is preferably 100 cs (centistokes) or more, particularly 10
It is preferably in the range of 10,000 to 1,000,000 cs.

This type of organopolysiloxane is usually obtained by cohydrolytically condensing one or more selected organohalogenosilanes, or a cyclic polysiloxane (such as a siloxane trimer or tetramer). It can be obtained by ring-opening polymerization using an alkaline or acidic catalyst.

Further, the reinforcing silica powder as the component (b) constituting the silicone rubber composition is essential for obtaining a silicone rubber having excellent mechanical strength, but for this purpose the specific surface area (BET method) is 100 m ² / g or more, particularly if preferably 150~300m ² / g or more, the mechanical strength of the cured product specific surface area is less than 100 m ² / g is low There is. Examples of the reinforcing silica include fumed silica and precipitated silica.

The amount of the reinforcing silica powder added is (a)
It is preferably 10 to 70 parts, especially 30 to 50 parts, relative to 100 parts (parts by weight, hereinafter the same) of the component organopolysiloxane, and if it is less than 10 parts, the addition amount is too small and a sufficient reinforcing effect is obtained. If it exceeds 70 parts, the workability may deteriorate and the mechanical strength of the obtained gasket may decrease.

As the curing agent as the component (c) constituting the above silicone rubber composition, conventionally known ones depending on the mechanism of the crosslinking reaction can be used.

When the molecular chain end of the organopolysiloxane of the component (a) is blocked with a non-hydrolyzable group, and when the crosslinking reaction is carried out by hydrocarbons, an organic peroxide is used as a curing agent. Oxides such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, 2,4-
Dicumyl peroxide, 2,5-dimethyl-bis (2,5-t-butylperoxy) hexane, di-t-
Butyl peroxide, t-butyl perbenzoate and the like are preferably used. The amount of this organic peroxide added is
The amount is preferably 0.5 to 5 parts with respect to 100 parts of the component (a) organopolysiloxane, or 0.1 to 1% by weight with respect to the entire silicone rubber composition.

Hydroxyl groups such as a hydroxyl group, an alkoxy group, an acetoxy group, an alkenyloxy group, an acyloxy group, an iminoxy group, an amino group, an amide group and an aminooxy group which are bonded to a silicon atom by a crosslinking reaction. When a condensation reaction such as dehydration reaction, dealcoholization reaction, decarboxylic acid reaction, deketone reaction, deoxime reaction, deamine reaction, deamidation reaction, etc. is carried out, that is, the molecule of the organopolysiloxane of component (a) If the chain end is blocked with a dimethylhydroxysilyl group or a dimethylalkoxysilyl group having a lower alkoxy group such as a methoxy group or an ethoxy group, a methyldialkoxysilyl group, a trialkoxysilyl group, etc., curing A metal organic acid salt and an organic amine are suitable as the agent. Specific examples of the metal organic acid salt and the organic amine include organic tin compounds such as dibutyltin dilaurate and tin dioctenoate,
Examples thereof include organic acid salts such as organic titanium compounds such as iron stearate, lead octylate, titanium tetrapropoxide and titanium tetrabutoxide, and amines such as dibutylamine and triethanolamine. In this case, if necessary, for example, methyltrialkoxysilane, ethyltrialkoxysilane, vinyltrialkoxysilane, phenyl having an alkoxy group such as methoxy group, ethoxy group, propoxy group, butoxy group, methoxyethoxy group, ethoxyethoxy group, etc. A cross-linking agent such as trialkoxysilane, tetraalkoxysilane, methyltributanooxime silane, methyltri (hexanoxime) silane, methyltri (isopropenoxy) silane, methyltriacetoxysilane, ethyl orthosilicate, propyl orthosilicate may be used. The addition amount of these curing agents is
0.01 to 1% by weight with respect to the silicone rubber compound
It is preferable that

Furthermore, when the diorganopolysiloxane of the component (a) has an alkenyl group directly bonded to a silicon atom, an organohydrogen containing at least two hydrogen atoms directly bonded to the silicon atom in one molecule. Genopolysiloxane may be used as a curing agent to crosslink and cure by these addition reactions. The organohydrogenpolysiloxane used here is
It may be linear, branched, or cyclic. For example, a diorganopolysiloxane end-capped with a dimethylhydrogensilyl group, a dimethylsiloxane unit and a methylhydrogensiloxane unit, and a terminal trimethylsiloxy unit may be used. Copolymer, dimethyl hydrogen siloxane unit (H (CH ₃ ) ₂ SiO _0.5 unit) and Si
Low viscosity fluid consisting of O ₂ unit, 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen- 1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-dihydrogen-3,7
-Dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane and the like. It should be noted that all of these organohydrogenpolysiloxanes preferably have a degree of polymerization of 300 or less.

The addition amount of the organohydrogenpolysiloxane as the curing agent is 50 to 500 mol% of hydrogen atoms directly bonded to the silicon atom with respect to the alkenyl group of the diorganopolysiloxane of the component (a). It is preferably used in proportion.

It is preferable to add a known platinum-based catalyst to this addition reaction.
Examples include platinum compounds, platinum complexes, chloroplatinic acids such as chloroplatinic primary acid and chloroplatinic secondary acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, ether compounds, complexes with various olefins, and the like. It is desirable that the amount of the platinum-based catalyst added be in the range of 1 to 2000 ppm as platinum atom based on the organopolysiloxane of the component (a).

The silicone rubber composition according to the present invention includes
In addition to the above-mentioned components (a) to (c), as an optional component, a filler such as crushed quartz or calcium carbonate may be added as an extender as long as it does not hinder the curing of the present invention.
Further, an inorganic or organic foaming agent for forming a sponge may be added. Examples of the foaming agent include azobisbutyronitrile, dinitropentamethylenetetramine, benzenesulfonhydrazide, azodicarbonamide, and the like, and the addition amount thereof is preferably in the range of 3 to 10 parts based on the silicone rubber compound. By thus adding the foaming agent, a sponge-like silicone rubber gasket can be obtained.

Further, it is optional to add various additives such as a colorant and a heat resistance improver, a reaction control agent, a releasing agent or a dispersant for a filler to the above composition, if necessary. However, diphenylsilanediol, various alkoxysilanes, carbon functional silanes, silanol group-containing low-molecular-weight siloxanes, etc., which are used as dispersants for fillers, are added in a minimum amount so as not to impair the effects of the present invention. It is preferable.

In the silicone rubber composition according to the present invention, the above-mentioned components are uniformly mixed using a rubber kneader such as a two-roll, Banbury mixer, do-mixer (kneader) or the like, and heat-treated as necessary. Can be obtained. In this case, for example, the organopolysiloxane of the component (a), the reinforcing silica powder of the component (b), and the like are mixed in advance to prepare a base compound, and the curing agent of the component (c) is added to and mixed with the base compound. It doesn't matter.

The silicone rubber composition thus obtained is a gasket required by various molding methods such as cast molding, mold pressure molding, extrusion molding, for example, corner gasket, joint seal gasket, zipper gasket. Etc., but these molded products are preferably post-cured at 100 to 200 ° C. for 30 minutes to 24 hours, if necessary.

The silicone rubber gasket of the present invention comprises the silicone rubber gasket obtained as described above, and the surface of the silicone rubber gasket (A) ethylene-propylene-diene copolymer,
(B) A cured coating of a rubber composition containing (H) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule and (C) platinum or a platinum compound. It is a thing.

Here, the ethylene-propylene-diene copolymer as the component (A) preferably has a propylene content of 40 to 70% by weight, particularly 40 to 60% by weight, and the diene monomer is For example, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene and the like are used. Further, this copolymer preferably has an iodine value of 1 to 40, particularly 5 to 30.

As such a copolymer, a commercially available polyolefin rubber component can be used, and specifically, EP22 (manufactured by Nippon Synthetic Rubber Co., Ltd.), Esplen 56
7 (Sumitomo Chemical Co., Ltd.), EPT3045 (Mitsui Petrochemical Co., Ltd.), EP33 (Nippon Synthetic Rubber Co., Ltd.)
Manufactured) and the like can be used.

Next, the organohydrogenpolysiloxane as the component (B) has at least two hydrogen atoms bonded to silicon atoms in one molecule. In this case, the above-mentioned organohydrogenpolysiloxane acts as a cross-linking agent, and for example, an organohydrogenpolysiloxane represented by the following general formula (2) and having at least two hydrogen atoms in one molecule is preferable. Used.

H _b R ² _c SiO _{(4-bc) / 2} (2) (wherein R ² is an unsubstituted or substituted monovalent hydrocarbon group excluding the same or different aliphatic unsaturated group) , Especially 1 to 10 carbon atoms
And alkyl groups such as methyl group, ethyl group, propyl group and butyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and β-phenylethyl group, cycloalkyl groups such as cyclohexyl group Group, etc., b is a positive number of 0.002 to 1.0, and c is 1.99 to
A positive number of 2.02 and b + c is 1.992 to 3.0. As specific examples of such organohydrogenpolysiloxane, compounds having the following structural formulas can be given.

[0032]

[Chemical 1] (1 is an integer of 2 to 10, m and n are integers of 0 to 10, respectively.)

The content of the component (B) is preferably 0.1 to 50 parts by weight based on 100 parts by weight of the component (A). If the amount is less than 0.1 part by weight, a sufficient crosslinking effect cannot be obtained, so that the cured film does not have sufficient strength, and when the silicone gasket is used, the film may be broken or peeled off. If the amount is more than 50 parts by weight, the degree of crosslinking of the cured film will be too high, and the flexibility of the silicone rubber gasket will not be able to be followed. When the gasket is bent, cracks will occur in the film, impairing the appearance and peeling off the film. It may fall. Therefore, the blending amount of the component B is preferably 0.1 to 50 parts by weight, and more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the component A.

Next, the platinum or platinum compound as the component (C) is a catalyst for promoting the addition reaction between the above-mentioned components (A) and (B), such as platinum, platinum black and chloroplatinic acid. , Complex salts of chloroplatinic acid with olefins or aldehydes, alcohol-modified chloroplatinic acid, and the like. The amount of platinum or platinum compound used may be a catalytic amount, but is appropriately increased or decreased depending on the composition so that the curing rate by the reaction of the components (A) and (B) is desired. The amount of platinum is preferably 1 ppm to 1% by weight based on the amount of the component (A) used.

When the surface of the silicone rubber gasket body is treated with the above ethylene-propylene-diene copolymer-containing rubber composition, the rubber composition is hydrolyzed in order to further improve the adhesiveness of the rubber composition. It is preferable to add a functional organic silicon compound.

Examples of such hydrolyzable organic silicon compounds include the compounds shown below.

[0037]

[Chemical 2]

The above rubber composition can be obtained by kneading the above-mentioned components in a predetermined amount with a two-roll mill, a kneader, a Banbury mixer or the like. At this time, a hydrocarbon-based synthetic oil such as liquid paraffin is used. , Lucant H
When C40 (manufactured by Mitsui Petrochemical Industry Co., Ltd.) or the like is added in a required amount, the viscosity of the composition is lowered and the workability can be improved.

In addition, the composition further contains optional components for adjusting the physical properties of the cured product, such as fumed silica, precipitated silica, aluminum silicate quartz powder, fused quartz powder, diatomaceous earth, and calcium carbonate. , Filler such as titanium dioxide, carbon black, anti-aging agent,
An ultraviolet absorber, a coloring agent, etc. can be added. The blending amount of the filler is 5 with respect to 100 parts of the component (A).
It is preferably not more than 00 parts, and when it is more than 500 parts, the cured product may be hard and brittle.

The silicone rubber gasket of the present invention has the above (A) to
It is obtained by laminating or coating a rubber composition to which the component (C), more preferably a hydrolyzable organic silicon compound is added, and curing the same.

In this case, as the laminating method, a method of laminating the above rubber composition on the surface of the silicone rubber gasket body by extrusion molding or the like and vulcanizing is preferably adopted, but hot air vulcanization is particularly preferable. In order to improve the elasticity of the surface layer, it is preferable to perform heat treatment at 150 to 200 ° C for 5 to 10 minutes. Further, after dissolving the above rubber composition in an appropriate solvent, the surface of the silicone rubber molded article is coated and impregnated by a usual coating method such as brush coating, dipping or spraying, and then the solvent is volatilized by air drying or the like. Alternatively, the curing may be performed under the same vulcanization conditions as described above. The thickness of this cured film is 0.0
It is preferably 1 to 10000 μm, and particularly preferably 0.1 to 1000 μm.

[0042]

The silicone rubber gasket of the present invention is
It has good weather resistance and creep resistance, and is excellent in non-contamination with respect to surrounding wall materials, column materials, glass plates, etc., and is useful as a building gasket or the like.

[0043]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, in the following example, a part shows a weight part.

[Example 1, Comparative Example 1] Dimethylsiloxane unit 99.825 mol%, methylvinylsiloxane unit 0.15 mol%, dimethylvinylsiloxane unit 0.
100 parts of raw rubber-like organopolysiloxane having an average degree of polymerization of 8,000 and consisting of 025 mol%, 3 parts of diphenylsilanediol as a dispersant, 4 parts of terminal silanol group dimethylpolysiloxane (degree of polymerization n = 10), and 40 parts of fumed silica (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g was added and heat-treated for 2 hours to prepare a base compound.

Next, 100 parts of this base compound was mixed with 2,4-dichlorobenzoyl peroxide / dimethylpolysiloxane (1,000 cs) as a curing agent.
1.5 parts of 50/50 paste was added and kneaded with two rolls to obtain a silicone rubber composition. This composition was extruded at 40 mmφ with an extruder of U / D = 12,
A tubular gasket having an outer diameter of 20 mm and an inner diameter of 16 mm was produced.

Next, this was continuously vulcanized under atmospheric pressure under vulcanization conditions of 300 ° C./5 minutes, and then cut into a length of 1 m.
Post-cure was performed at a temperature of 1 hour for 1 hour to obtain a silicone rubber molded product.

On the other hand, ethylene-propylene-diene co-weight
Combined (Polyolefin synthetic rubber EP22 (Japan Synthetic Goro
2) by dissolving the iodine value 22) manufactured by Mu Co., Ltd. in toluene.
It was a 0% rubber-toluene solution. Formula C in 100 parts of this solution
₆H_FiveSi [OSi (CH₃)₂H ]₃Organo indicated by
Hydrogen polysiloxane 5 parts, 5% of chloroplatinic acid
0.1 parts of isopropyl alcohol solution, 1-ethynyloxy
Add 0.2 parts of crohexan-1-ol, mix,
A system composition / toluene solution was obtained.

Next, a rubber composition / toluene solution is sprayed on the surface of the above silicone rubber molded product by a sprayer so that the adhesive force is about 30 μm at a pressure of 2-3 kgf / cm ² , and the composition is sprayed at room temperature for 10 minutes. After drying for 10 minutes at 50 ° C. for 15 minutes, it was held in an oven at 200 ° C. for 15 minutes to cure it.

Then, this product was cut into a piece of 20 cm in length, and it was adhered on a glasall board with screws, and this was attached to 4
It was fixed to an outdoor exposure device having an inclined surface of 5 °, and the degree of stain was visually observed with the passage of half a year. The results are shown in Table 1.

For comparison, a similar test was performed on the above-mentioned rubber composition / toluene solution which was not treated.

[0051]

[Table 1]

[Examples 2 and 3] 100 parts of the above rubber composition / toluene solution was mixed with γ as a hydrolyzable organosilicon compound.
Example 1 except that 3 parts each of methacryloxypropyltrimethoxysilane or vinyltrimethoxysilane was added.
The same treatment was carried out in the same manner as described above, and the adhesion of the cured film of the rubber composition / toluene solution to the silicone rubber molded product was evaluated. The results are shown in Table 2.

[0053]

[Table 2]

From the results shown in Table 1, it was confirmed that the silicone rubber gaskets according to the Examples were superior in non-staining property to those not coated with the rubber composition / toluene solution (Comparative Example). From the results of Table 2, it was confirmed that the one to which the hydrolyzable organic silicon compound was added was excellent in the adhesiveness of the ethylene-propylene-diene copolymer cured film to the silicone rubber gasket body.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location // C08L 23/16 LCY 7107-4J (72) Inventor Shin Sekiguchi 1st place in Hitomi, Oita, Matsuida-cho, Usui District, Gunma Prefecture 10 Shin-Etsu Chemical Co., Ltd. Silicon Electronic Materials Technology Laboratory

Claims (2)

[Claims] 1. An ethylene-propylene-diene copolymer (A) on the surface of a silicone rubber gasket body, (B)
An organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule,
(C) A silicone rubber gasket comprising a cured coating of a rubber composition containing platinum or a platinum compound. 2. The silicone rubber gasket according to claim 1, wherein a hydrolyzable organosilicon compound is blended with the rubber composition.