JPH05230436A - Sealing member coated with polyorganosiloxane - Google Patents

Abstract

PURPOSE:To prepare a sealing member which allows no separation of a coating film even when rubbed for a long term, has stable characteristics, and does not adhere to a mating material (metal, rubber) while retaining the properties inherent in rubber. CONSTITUTION:A sealing member is prepd. by coating the surface of a rubber with a polyorganosiloxane compsn. and crosslinking the compsn. by photoreaction to thereby bond it to the rubber. The compsn. has an average degree of polymn. of 20-10,000 and is represented by the mean compsn. formula: RaSiO(4-a)/2 (wherein a is a positive number of 1.900-2.100; and 0.01-25mol% of Rs essentially include unsatd. groups and/or phenyl ketone groups and optionally include one or more kinds of groups selected from the group consisting of H, hydroxyl, alkoxy, acetoxy, oxime, enoxy, amino, amide, aminoxy, epoxy, mercapto, and ester groups, and the rest of Rs are a 1-15C hydrocarbon group and/or its fluorinated deriv.).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing material in which the polyorganosiloxane composition is coated on the surface of rubber and then crosslinked and adhered by photoreaction to improve the adhesiveness between rubber products and between rubber products and metal.

[0002]

2. Description of the Related Art NBR, ACM, as a sealing rubber material for packings, O-rings, gaskets, oil packings, etc.
CR, FKM, etc. are used. When left in a compressed state for a long time in a metal, which is a material that comes into contact with it, there is a problem that the rubber material and the metal are fixed. Sticking refers to a phenomenon in which a metal reacts with rubber, and a part of the rubber material adheres to the metal when the rubber material is peeled off. In particular, when the seal material is used under lubricating oil, the rubber seal material and the metal are apt to adhere to each other, which not only deteriorates the sealing performance but also reduces workability when replacing parts. In addition, there is also a problem that when rubber products are stacked or packaged, they are bonded to each other to cause blocking. Conventionally, as a method for preventing sticking and sticking, (1) a method of forming a coating film of resin or the like on a rubber molded product (Japanese Patent Laid-Open No. 63-295648), (2) a method of curing a rubber molded product with a chemical ( Japanese Patent Publication 54-366
30) and (3) there is a method of coating reactive polysiloxane (JP-A-3-217435), but these cannot be kept airtight with the mating material, or are expensive in cost, or treated. There is a problem that it takes a long time or the adhesion to the metal under the lubricating oil is not sufficiently improved. In addition, the UV curing method is generally cheaper in construction cost than the heat curing method, and in terms of energy, it is 75 to 90% of the heat curing method.
It is said that the energy of can be extinguished. Therefore, the thermal reaction requires a lot of energy and is economically disadvantageous.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention have proposed a surface treatment method which does not stick or stick to a mating material without substantially lowering the original properties (flexibility and mechanical strength) of rubber. As a result of investigation, it was found that such a problem can be effectively solved by irradiating a specific siloxane with light such as ultraviolet rays.

[0004]

Means for Solving the Problems The inventors of the present invention, after coating a specific composition of a polyorganosiloxane compound as a coating agent used on the surface of a rubber as a sealing material, on the surface of the rubber, carry out crosslinking adhesion by photoreaction. As a result, they have found a sealing material whose surface tackiness is reduced and whose coating is not peeled off even by friction or the like, and completed the present invention.

The coating composition of the present invention has an average compositional formula R _a SiO _{(4-a) / 2} (where a is a positive number of 1.900 or more and 2.100 or less, and 0.01 of R is 0.01). 25 mol% has an unsaturated group and / or a phenyl ketone group as an essential component, or these and a hydrogen atom, a hydroxyl group, an alkoxy group, an acetoxy group,
It contains one or more substituents selected from oxime group, enoxy group, amino group, amide group, aminoxy group, epoxy group, mercapto group and ester group, and the remaining R is saturated with 1 to 15 carbon atoms. It is a hydrocarbon group and / or a fluorine group-substituted product thereof. ) Average degree of polymerization 20 to 1
A sealing material is provided in which a rubber surface is coated with a composition containing 0000 polyorganosiloxane, and then the polyorganosiloxane composition is crosslinked and adhered by photoreactive crosslinking. The polyorganosiloxane composition applied to the surface of the sealing material of the present invention is represented by the average composition formula _Ra SiO _{(4-a) / 2} , and the value of a in the formula is from 1.900 to 2.100. It is a positive number, preferably in the range of 1.950 to 2.050, and when a is less than 1.900, the elongation of the coating film is low, the elongation of the substrate cannot be followed, and it exceeds 2.100. And the strength of the coating film is not sufficient, which is not preferable.

Of R, 0.01 to 25 mol% contains an unsaturated group and / or a phenylketone group as essential components,
Alternatively, a hydrogen atom, a hydroxyl group, an alkoxy group, an acetoxy group, an oxime group, an enoxy group, an amino group, an amide group, an aminoxy group, an epoxy group, a mercapto group, and one or more substituents selected from ester groups. Yes,
These substituents may be at the ends or within the polyorganosiloxane molecule. As the unsaturated group, for example, vinyl group, allyl group, vinyloxy group, acryloxy group,
Methacryloxy group and maleimide group are mentioned. Of R, the unsaturated group and / or phenylketone group is preferably in the range of 0.01 to 10 mol%. When the amount of the above substituents is small, the adhesive strength tends to be poor, and when it is too large, the elongation of the coating film tends to be poor.

Residual R bonded to the silicon atom is a hydrocarbon group having 1 to 15 carbon atoms, specifically, an alkyl group having 1 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, Examples thereof include an aralkyl group having 7 to 10 carbon atoms and / or a fluorine-substituted product thereof, preferably a methyl group, a phenyl group, and a 1,1,1-trifluoropropyl group. The average degree of polymerization of polyorganosiloxane is 20 to 10
000, preferably 100 to 6000. If the average degree of polymerization of the polyorganosiloxane is less than 20, the strength of the coating film is insufficient, and if it exceeds 10,000, the flowability of the polyorganosiloxane solution is poor and the workability is poor. ..

With an unsaturated group as an essential component, a methyl group, a hydrogen atom, and
Polyorganosiloxane having one or more substituents selected from a hydroxyl group, an alkoxy group, an acetoxy group, an oxime group, an enoxy group, an amino group, an amide group, an aminoxy group, an epoxy group, a mercapto group and an ester group. Three
It may be a mixture of 100 parts by weight or less. The polyorganosiloxane of the present invention may further contain a sensitizer and / or an organic peroxide, silica if necessary, and a polymer other than silicone rubber. Examples of the sensitizer used in the present invention include benzoic acid and its esters, acetophenones, propiophenones, ketals, acetals, benzophenones, benzoins, and benzyl, and examples thereof include p-dimethylamino. Methyl benzoate, ethyl o-dimethylaminobenzoate,
2-Ethylhexyl p-dimethylaminobenzoate, 2,
2-diethoxyacetophenone, benzylmethyl ketal, benzyl-β-methoxyethyl acetal, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzophenone, methyl o-benzoylbenzoate, bis ( 4-methylaminophenyl)
Ketone, 4,4'-bisdiethylaminobenzophenone, benzyl, benzoin (2-phenyl-2-hydroxyacetophenone), benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, 4'- Examples include isoprop-2-hydroxy-2-methylpropiophenone and p-dimethylaminoacetophenone. The amount of the sensitizer added is preferably 5 parts by weight or less with respect to 100 parts by weight of the polyorganosiloxane.

The organic peroxide used in the present invention is an organic peroxide which is easily decomposed when used in combination with a sensitizer, such as dialkyl oxides, diacyl peroxides, alkylacyl peroxides and peroxyesters. , Peroxydicarbonate, for example, 1,1-di (t-butylperoxy) -3,3,5.
-Trimethylcyclohexane, t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl- 2,5
-Di (t-butylperoxy) hexyne-3, α, α '
-Bis (t-butylperoxy-m-isopropyl) benzene, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and the like can be mentioned. These organic peroxides can be used alone or in combination of two or more. Organic peroxide is polyorganosiloxane 1
0.01 to 20 parts by weight is preferable with respect to 00 parts by weight.
In addition, powders of polytetrafluoroethylene, polyethylene, etc., and carbon graphite may be added to the polysiloxane in order to make the polyorganosiloxane more tack-free. The blending amount is preferably 60 parts by weight or less with respect to 100 parts by weight of polysiloxane.

The rubber component which is the base material of the sealant of the present invention includes chloroprene rubber, ethylene / α-olefin copolymer rubber, butyl rubber and its halides, brominated or chlorosulfonated polyethylene, acrylic rubber (ACM). ), Ethylene / acrylic rubber, epihalohydrin rubber, butadiene / acrylonitrile rubber (N
BR) and hydrogenated products thereof, styrene-butadiene rubber and hydrogenated products thereof, butadiene-acrylonitrile-acrylic acid ester copolymer and hydrogenated products thereof, and fluororubber (FKM).

To the above raw material rubber, known compounding agents are added,
It is molded as a sealing material and vulcanized by a known vulcanization system.
The polyorganosiloxane used in the present invention has a viscosity of 3
It is preferable to apply in a state of 0000 cst or less,
If necessary, it is diluted with a solvent before use. As the solvent used for diluting the polyorganosiloxane, ketones, hydrocarbons, halogenated hydrocarbons, esters,
Examples of the solvent include ethers, alcohols, freons, and siloxanes. Examples thereof include acetone, methyl ethyl ketone, methyl isopropyl ketone, n-hexane, cyclohexane, heptane, toluene, xylene, carbon tetrachloride, trichloroethane, trichloroethylene, and acetic acid. Ethyl, propyl acetate, butyl acetate, tetrahydrofuran,
Examples include isopropyl alcohol. These solvents are used alone or as a mixture of two or more.

In order to coat the rubber surface uniformly, it is preferable to use a dilute solution in which the concentration of polyorganosiloxane in the solvent is 0.001 to 3% by weight. Examples of the method for coating the surface of the molded product of polyorganosiloxane include dip coating, spray coating, brush coating, knife coating, and roll coating, but are not particularly limited. The number of times of coating can be once or several times. The thickness of the polyorganosiloxane coating on the rubber surface is 0.1 to 50 μm, preferably 1 to 30 μm.

The crosslinking reaction between the polyorganosiloxanes coated on the surface of the rubber used in the present invention and the initiation reaction of the adhesion between the rubber and the polyorganosiloxane are carried out by irradiation with light such as electron beam, radiation, ultraviolet ray or laser. Irradiation sources include low pressure, high pressure or ultra high pressure mercury lamps, hydrogen, argon,
A discharge tube such as neon, xenon or bromine, a xenon lamp, a YAG laser, a maxima laser, etc., and an electron beam and radiation are used. The irradiation condition is 50
The temperature is preferably 10 minutes or less in an atmosphere of 0 ° C., and more preferably at room temperature of 0.
Conditions of 02 to 3 minutes are preferable. When the treatment conditions become strict, the deterioration reaction of the molded rubber easily occurs, and in the opposite case, the coating film is not sufficiently cross-linked and adhered, and the strength of the coating film is deteriorated, causing a problem in durability.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples. Manufacture of rubber sheet base material The composition shown in Table 1 was kneaded with a Banbury mixer, rolled into a sheet having a thickness of 5 mm, and press-vulcanized and secondary vulcanized under the conditions shown in Table 2 to obtain a sheet having a thickness of 2 mm. A rubber sheet base material was obtained.

[0015]

[Table 1]

Synthesis of Modified Polysiloxane 1. Methacryloxy group-containing polysiloxane 50 g of both-end silanol group-containing polydimethylsiloxane (viscosity 2000 cst) and 1 g of γ-methacryloxypropyltrimethoxysilane were placed in a reaction vessel equipped with a stirring and cooling device, and reacted at 80 ° C. for 10 hours under a nitrogen stream. ,
The methanol produced was removed by an ester adapter equipped with a cooling device to obtain a methacryloxy-containing polysiloxane having a viscosity of 10,000 cst. This compound is designated as Si-1. 2. Polysiloxane containing vinyl group 50 g of polydimethylsiloxane containing silanol groups at both ends (viscosity 2000 cst), vinyltriethoxysilane 1
g was reacted in the same manner as in 1 to obtain a vinyl group-containing polysiloxane having a viscosity of 10,000 cst. This compound is Si-2
And 3. Polysiloxane containing vinyl groups and amino groups 50 g of polydimethylsiloxane containing silanol groups at both ends (viscosity 2000 cst), 0.5 g of vinyltriethoxysilane, 0.5 g of γ-aminopropylmethoxysilane
And were reacted in the same manner as in 1 to obtain a vinyl group- and amino group-containing polysiloxane having a viscosity of 10,000 cst. This compound is designated as Si-3.

4. Methacryloxy group- and epoxy group-containing polysiloxane 50 g of both-end silanol group-containing polydimethylsiloxane (viscosity 2000 cst), 0.5 g of γ-methacryloxypropyltrimethoxysilane, 0.5 g of γ-glycidoxypropyltrimethoxysilane are the same as 1 To obtain a polysiloxane containing a methacryloxy group and an epoxy group having a viscosity of 10,000 cst. This compound is S
i-4. 5. Vinyl group-containing silicone rubber 0.5 mol% -containing vinyl group-containing polydimethyl silicone rubber is referred to as Si-5.

[0018]

[Table 2]

Examples 1 to 15 and 18 ACM was used as a rubber sheet base material. The polyorganosiloxane shown in Table 3 was diluted with cyclohexane to obtain a coating solution of 1% by weight. Next, the surface of the vulcanized rubber (ACM) of the rubber sheet substrate was spray coated with the coating solution, dried at room temperature, and the solvent was volatilized. Then, it was irradiated with ultraviolet rays (200 W low-pressure mercury lamp) for 60 seconds to obtain a rubber sheet to which polyorganosiloxane was cross-linked. The thickness of the siloxane coating at that time was 1 μm.

[0020]

[Table 3]

Examples 16 and 17 The rubber sheet base material was treated in the same manner as in Example 10 except that NBR and FKM were used, to obtain a rubber sheet to which polyorganosiloxane was cross-linked. Comparative Example 1 The polyorganosiloxane shown in Table 3 was diluted with cyclohexane to obtain a 1% by weight coating solution. Next, using ACM as a rubber sheet base material, the coating solution was spray-coated on the surface and dried at room temperature to volatilize the solution. Comparative Examples 2 and 3 The polyorganosiloxane shown in Table 3 was diluted with cyclohexane to obtain a 1 wt% coating solution. Next, using ACM as a rubber sheet base material, the coating solution was spray-coated on the surface thereof and dried at room temperature to volatilize the solvent. Then, it was thermally crosslinked in a hot air gear oven at 170 ° C. for 20 minutes to obtain a rubber sheet base material. Comparative Example 4 The rubber surface of the rubber sheet base material of ACM was used without any treatment.

Evaluation Method 1) Shearing Force (Adhesiveness) As an index for checking the adhesiveness between the rubber sheets, the rubber sheet materials were overlaid and the shearing force was measured. As the sample pieces, those obtained by cutting out the rubber sheet materials obtained in Examples 1 to 18 and Comparative Examples 1 to 4 to 5 cm × 1.4 cm were used. Then, after overlapping the rubber sheet surfaces of the sample pieces and applying a load of 1.5 kg / cm ² at 80 ° C. for 3 days, a Tensilon universal tensile tester (manufactured by Orientec) was used to check the adhesiveness. And pulling speed 50mm
Shear force was measured at / min. The results are shown in Table 4. 2) Shearing force after rubbing with a cloth Even if the polysiloxane film is formed on the rubber surface of the rubber sheet material and the adhesive property is reduced, if the film falls off due to long-term friction or rubbing, the original adhesive Return to sex. Therefore, the adhesion of the coating film to the base rubber was examined by the following method. The same sample piece used for measuring the shearing force was used. That is, after rubbing the silicone-coated elastomer surface with a cloth, the shearing force was measured in the same manner as in Evaluation method 1). The results are shown in Table 4. 3) Adhesion test A vulcanized sheet rubber with a thickness of 2 mm was cut into 25 × 100 mm strips, and a metal plate (25 × 1
00 × 1.6 mm) (using the metal species shown in Table 4) was used by using a crimping device (a crimping device used for a compression set test defined in JIS K6300. It consists of two or more flat compression plates and bolts and nuts that secure the compression plates. At that time, the tightening force of the nut was set to 100 kgf · cm with a torque wrench. Put the crimping device in a closed container filled with oil, and
After soaking for 6 hours, take it out, and use a Tensilon universal tensile tester (manufactured by Orientec) to measure the adhesive force (peeling force) between the test piece and the metal, pulling speed 50 mm / m
The T-type peeling test was performed with in to measure the peeling force. At that time, the state of being adhered to the metal was visually confirmed. The results are shown in Table 4.

[0023]

[Table 4]

In Examples 1 to 15, the adhesion between rubbers (shearing force), the adhesion between the rubber base material and the coating film (shearing force after rubbing with a cloth), and the peeling force after the adhesion test You can see that it is small. In Examples 16 and 17, similar results were obtained with NBR and FKM in addition to ACM as the rubber base material, and it can be seen that the effect is obtained even if the rubber type is changed. In Example 18, changing the metal species to an aluminum alloy is effective, and changing the metal species is effective. In Comparative Examples 1, 2, and 3, the tackiness is improved, but the adhesion and sticking between the rubber substrate and the coating film are poor. In Comparative Example 4, it can be seen that the adhesiveness, durability, and sticking are inferior.

[0025]

INDUSTRIAL APPLICABILITY According to the present invention, the coating does not fall off even if it is rubbed over a long period of time and is rubbed, its properties are stable, and the original properties of the rubber are not substantially deteriorated. The present invention relates to a sealing material that does not stick to the. In addition, light irradiation equipment is cheaper than thermosetting reaction equipment,
Moreover, since the irradiation can be performed for a short time, the running cost in manufacturing is low.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ken Akiyama 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. An average composition formula R _a SiO _{(4-a) / 2} (where a is a positive number of 1.900 or more and 2.100 or less, and 0.01 to 25 mol% of R is unsaturated. Group and / or phenyl ketone group as an essential component, or with these, a hydrogen atom, a hydroxyl group, an alkoxy group, an acetoxy group,
It contains one or more substituents selected from oxime group, enoxy group, amino group, amide group, aminoxy group, epoxy group, mercapto group and ester group, and the remaining R is saturated with 1 to 15 carbon atoms. It is a substituted hydrocarbon group and / or fluorine group. ) Average polymerization degree 20 to 100
A sealing material obtained by coating a rubber surface with a composition containing a polyorganosiloxane of No. 00, and then cross-linking and adhering the polyorganosiloxane composition by photoreaction.