JPH0624800B2 - Adhesive silicone rubber structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive structure, and particularly to an adhesive structure having excellent weather resistance, heat resistance and cold resistance.

<< Prior Art >> As an electrical insulating tape for applications such as terminal treatment of electric wiring, vinyl chloride adhesive tape (adhesive layer: polyisobutylene, SBR), polyester adhesive tape (adhesive layer: acrylic, rubber) are usually used. Etc. are used. In this case, as the rubber-based pressure-sensitive adhesive, natural rubber, SBR, butyl rubber, or other rubber to which a tackifying resin such as terpene resin, rosin ester, or petroleum resin is added is used. Although it has the advantage of exerting power, it has the drawback of poor cohesive strength at high temperatures and insufficient heat resistance.

On the other hand, the acrylic pressure-sensitive adhesive contains a higher alcohol ester of methacrylic acid as a main component and has cohesive strength and heat resistance even at a relatively high temperature, but has a drawback that the initial adhesive strength at a low temperature is low. Further, the base material such as vinyl chloride or polyester itself is inferior in weather resistance, heat resistance and cold resistance, so that it may deteriorate during long-term use.

On the other hand, as an electric insulating tape having a heat resistant temperature of 180 ° C. class (H type), there is a tape using a glass cloth, a polyimide film, a fluorine film or the like as a substrate and a silicone adhesive as an adhesive layer. In this case, the silicone pressure-sensitive adhesive has an advantage that it has excellent initial adhesiveness and cohesive force at low and high temperatures and has adhesiveness to most adherends, but it has a special release layer (separator). However, there is a disadvantage that the force required for peeling the separator from the adhesive layer is too large. Especially after storage for a long period of time, the adhesive layer or the separator may be broken during peeling. In addition, it is extremely difficult to remove it once it is attached to the adherend, which causes a problem in work.

Furthermore, a crosslinked or uncrosslinked butyl rubber-based or ethylene propylene rubber-based tape as a rubber-based self-fusing tape,
A tape in which a polyethylene tape and a butyl rubber-based pressure-sensitive adhesive layer are bonded together, a tape in which boric acid is added to silicone rubber and then cured to impart self-bonding property, and the like are known. However, these self-bonding tapes have the drawback that the tapes must be destroyed if it is necessary to peel them off for repair after fusion, and they cannot be reused once they are peeled off. In addition, other than silicone rubber, there is a defect that weather resistance, heat resistance and cold resistance are poor.

The present inventors have conducted extensive studies to solve the above-mentioned drawbacks, and as a result, employ a silicone rubber as a base material and provide a silicone rubber layer having adhesiveness other than the conventional silicone adhesive to form a normal separator. Not only can it be used, but the adhesive strength can be adjusted, and since both the base material and the adhesive layer are made of silicone rubber, it is significantly improved over the conventional adhesive structure in terms of weather resistance, heat resistance and cold resistance. The inventors have found that they can be done, and have reached the present invention.

<< Problems to be Solved by the Invention >> Therefore, a first object of the present invention is to provide an adhesive structure excellent in weather resistance, heat resistance and cold resistance.

A second object of the present invention is to provide an adhesive structure excellent in workability as well as weather resistance, heat resistance and cold resistance.

<< Means for Solving the Problems >> The above-mentioned various objects of the present invention are provided on at least one surface of a silicone base material, and the silicone rubber base material.
Organopolysiloxane containing no SiO _4/2 units and having a vinyl group at the terminal and / or side chain, an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule, and a platinum catalyst. And a silicone rubber layer having tackiness, which is obtained by curing a liquid or solution type silicone rubber in which the molar ratio of the vinyl group and the hydrogen atom bonded to the silicon atom is 0.02 to 0.8 by an addition reaction. Achieved by a tacky silicone rubber structure characterized in that

The silicone rubber compound in the silicone rubber substrate of the present invention can be appropriately selected and used from the commonly used ones. (In the formula, R represents a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, an aryl group such as a phenyl group and a tolyl group, an alkenyl group such as a vinyl group, an allyl group, or the like. A chloromethyl group, a trifluoropropyl group or the like in which some or all of the hydrogen atoms of the group are substituted with halogen atoms or the like, and a is 1.98 to 2.0.
It is a number of two. The main component is an organopolysiloxane represented by the formula (1), and a reinforcing silica such as silica hydrogel or silica aerogel is added thereto. The organopolysiloxane may be in the form of oil or raw rubber, but usually has a kinematic viscosity at 25 ° C. of 100
It is preferably 0 cs or more. This silicone rubber compound contains carbon black, graphite, silver, nickel, and other metal powders as a conductivity-imparting agent, glass beads, silica, phenol resin powder, and other composite conductive powders coated with silver, nickel, carbon fibers, and nickel. Conductive fiber such as fiber, heat resistance improver such as titanium oxide, red iron oxide, cerium oxide, etc., quartz powder as inorganic filler,
Diatomaceous earth or the like may be added, and a pigment or the like may be added for coloring.

In the present invention, a silicone rubber compound containing an additive such as the above-mentioned pigment is treated by a radical reaction of an organic peroxide or an addition reaction of a vinyl group-containing siloxane with an organohydrogenpolysiloxane by a platinum-based catalyst to obtain the silicone rubber compound. The compound is cured to form the substrate. In this case, the base material may be reinforced with glass cloth or the like.

The adhesive silicone rubber of the present invention is mainly composed of the same organopolysiloxane as the silicone rubber compound in the above-mentioned silicone rubber substrate, Select one that does not include units.

This adhesive silicone rubber is in a liquid state or a solution state before being cured. In the case of a liquid state, the organopolysiloxane has a kinematic viscosity at 25 ° C. of 100,000 cs (viscosity of 100,0).
00 cp) or less is preferable.

As in the case of the base material, reinforcing silica, a conductivity-imparting agent, a heat resistance improver, an inorganic filler, a pigment and the like may be added to the organopolysiloxane.

Further, when a silicone rubber compound comprising this organopolysiloxane, a curing agent and optionally added various fillers is made into a solution, it is dissolved in an organic solvent such as toluene, xylene or trichloroethylene to obtain a viscosity suitable for coating. Adjust to.

In order to impart the tackiness, which is a feature of the present invention, to the silicone rubber, it is necessary to make the crosslink density of the silicone rubber smaller than usual. Examples of such a curing method include radical reaction by addition of organic peroxide, addition reaction of vinyl group-containing siloxane and hydrogen polysiloxane with platinum-based catalyst, or silanol group of organopolysiloxane terminal with organotin-based catalyst, etc. And an organosilicon compound having a hydrolyzable group such as an alkoxy group, an acetoxy group, an alkenyloxy group, or a ketoxime group. In the present invention, of these methods, the addition reaction between a polysiloxane having a vinyl group and a hydrogen polysiloxane is used because the crosslinking density can be easily controlled and the curing rate is high.

This addition reaction system comprises an organopolysiloxane having a vinyl group at a terminal and / or a side chain, an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom in one molecule, and a platinum catalyst. The molar ratio S of vinyl group and SiH group is S in order to obtain tackiness.
iH / Si and (CH = CH ₂₎ needs to be in the range of 0.02 to 0.8. If the molar ratio is 0.8 or more, the adhesive strength is too weak, and if it is 0.02 or less, a predetermined strength cannot be obtained.

Next, the method for producing the adhesive silicone rubber structure of the present invention will be described in detail.

The silicone rubber substrate is manufactured by adding a curing agent to a predetermined silicone rubber compound, molding it into a sheet or tape with a rubber extruder or a calender roll, and thermally curing it in a heating furnace. At this time, a silicone rubber compound containing a curing agent may be placed on a PET film or the like and molded.

Then appropriate to the desired _{SiH / Si (CH = CH 2} ) coating or dipping a and viscosity by blending the ratio 10 to 5
The adhesive silicone rubber adjusted to 10,000 cp was applied to the obtained silicone rubber base material with an air doctor coater,
Coating on one side or both sides by post-measurement method such as blade coater, knife coater, impregnation coater or pre-measurement method such as reverse roll coater, gravure coater, kiss roll coater, cast coater, spray coater, etc., and contains organic solvent In some cases, it is pre-dried and then placed in a heating oven to be heat-cured. This adhesive silicone rubber structure is wound with a separator such as a polyethylene (PE) or polyester (PET) film and cut into a predetermined width with a slitter or the like to obtain a product. In this case, in order to enhance the adhesion between the silicone rubber base material and the adhesive silicone rubber, a known primer may be applied to the base material and then the adhesive layer may be provided.

This adhesive silicone rubber structure is not limited to a sheet-like one, but an adhesive silicone rubber layer may be provided on the surface of a silicone rubber molded product formed by a mold or the like.

1 to 3 show sectional configurations of typical embodiments of the structure.

FIG. 1 shows a case where an adhesive silicone layer is provided on one side of a silicone rubber substrate, FIG. 2 shows a case where an adhesive silicone rubber layer is provided on both sides, and FIG. 3 shows a silicone rubber substrate reinforced with glass cloth. This is the case.

When actually performing the work using the adhesive silicone rubber structure of the present invention, it is sufficient to simply wind the work, and the holding time required in the case of the self-bonding tape is not necessary, so that the work time can be shortened. You can In addition, it can be reused because it retains its tackiness even though it can be easily peeled off during repair.

In the present invention, the adhesive force of the adhesive silicone rubber layer can be controlled so that the adhesive force can be maintained even at low and high temperatures. Further, since the cohesive force is strong, it can be peeled off and reused even if the adhesive layers are stuck together. Furthermore, as an organopolysiloxane for the adhesive layer Since a normal silicone pressure-sensitive adhesive containing units is not used, a special separator is not required, and a normal separator such as PE, PET, or vinyl chloride film can be used.

The adhesive silicone rubber structure of the present invention can be used for various purposes. For example, since it is excellent in heat resistance, cold resistance, and electric characteristics, it can be used as an end treatment tape for electric wires, an electric insulating tape or sheet, a tape or sheet for construction sealing, a label for low temperature, and the like. In addition, a silicone rubber base material and an adhesive silicone rubber, which are made conductive by adding a conductivity-imparting agent such as carbon black, graphite, and metal powder, can be used as a biomedical electrode used for electrocardiogram, electroencephalogram measurement and the like.

<< Effects of the Invention >> The adhesive structure of the present invention uses silicone rubber as a base material,
Since it has a silicone rubber layer having an adhesive property on at least one surface thereof, the whole is excellent in weather resistance, heat resistance, and cold resistance, and also has stretchability and flexibility, so that it follows the covering body well, Not only can it be sufficiently adhered, but it can also be peeled off and reused after it has once adhered, so workability is extremely good.

<< Examples >> The present invention will be described in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1. Organic peroxide C-2 in 100 parts of silicone rubber compound KE151u (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.)
(Shin-Etsu Chemical Co., Ltd. trade name) was added and mixed with 1.2 parts of two rolls. This was extruded into a tape with a thickness of 1 mm and a width of 20 mm at a speed of 3 m / min with a rubber extruder having a cylinder inner diameter of 40 mm, and then passed through a heating furnace at a temperature of 250 ° C. and a length of 1 m to cure the silicone rubber tape. It was This tape was heat treated in a hot air dryer at 200 ° C for 4 hours,
A silicone rubber base material was used.

Next, a kinematic viscosity of 95 mol% of dimethylsiloxane units and 5 mol% of methyl vinyl kiloxane units was 10,000.
100 parts of cs methylvinylpolysiloxane and 42 parts of quartz powder (average particle size 1 μ) were kneaded with a gate mixer, and 15
After heat treatment was performed at 0 ° C. for 2 hours, the mixture was homogenized with a mixing triple roll. To 100 parts of this base, 0.2 part of an isopropyl alcohol solution of chloroplatinic acid (platinum amount: 2% by weight), 0.1 part of acetylene alcohol and the formula Was added and mixed with 3 parts of methylhydrogenpolysiloxane represented by. The ratio of _{SiH / Si (CH = CH 2} ) was 0.090. The viscosity of this liquid silicone rubber was 27,000 cp.

This liquid silicone rubber was coated on one surface of the silicone rubber substrate with a rod coater and heated at 200 ° C. for 10 minutes to form an adhesive silicone rubber layer having a thickness of 50 μm.

The adhesive silicone rubber structure obtained as described above was allowed to stand at room temperature for 48 hours, and then the adhesive silicone rubber structure was adhered to a PET sheet having a thickness of 100 μm, and the JIS
-Rubber roller with a load of 2 kg described in Z0237 is reciprocated and crimped once, and then a peeling angle of 180 using a tensile tester.
Peel off the PET sheet at a peeling speed of 0.3 m / min.
When the adhesive strength (initial adhesive strength) was measured, it was 16 g / 20 mm.
Met.

Next, the adhesive surfaces of the adhesive silicone rubber structure were stuck together, stored at room temperature and 80 ° C. under a constant load of 40 g / cm ² for 48 hours, and then the adhesive force (blocking force) was measured by the same method. As a result, 40g / 2 at room temperature
It was 0 mm and 170 g / 20 mm at 80 ° C. Further, the structure after peeling was adhered to a PET sheet having a thickness of 100 μm, and the adhesive strength (re-adhesive strength) was measured by the same method. Both at room temperature and at 80 ° C., 15 g / 2
It was 0 mm, and had a good adhesive force almost equal to the initial adhesive force.

Example 2. An adhesive silicone rubber structure was prepared in the same manner as in Example 1 except that the amount of methylhydrogenpolysiloxane used was 2.5 parts and the ratio of SiH / Si (CH = CH ₂ ) was 0.075. When prepared and evaluated in the same manner, the initial adhesive force was 20 g / 20 mm, and the blocking force at room temperature and 80 ° C. was 49 g / 20 mm and 220 g, respectively.
/ 20mm, re-adhesion strength at room temperature and 80 ℃ is 20 respectively
g / 20 mm and 18 g / 20 mm, and good results similar to those in Example 1 were obtained.

Comparative Example Silicone rubber base material obtained in Example 1 was obtained by adding 1.2 parts of benzoyl peroxide as an organic peroxide to 100 parts of silicone adhesive KR-130 [trade name: manufactured by Shin-Etsu Chemical Co., Ltd.]. Coated on one side with a rod coater and heated at 200 ° C for 10 minutes to a thickness of 60 μm
Of the silicone adhesive layer. When various evaluations were performed on the adhesive structure thus obtained in the same manner as in Example 1, the initial adhesive force was 325 g / 20 mm.
The blocking force was not measurable not only at 80 ° C. but also at room temperature because the adhesive layer was broken.

The results of the above-described comparative examples are summarized in Table 1.

From the results shown in Table 1, the adhesive silicone rubber structure of the present invention has a smaller initial adhesive force than the one using the conventional silicone adhesive, but does not block even when the adhesive surfaces are stuck to each other, and even after peeling. It was demonstrated that the adhesive strength was maintained.

Example 3 100 parts of a conductive silicone rubber compound KE3611u [trade name: manufactured by Shin-Etsu Chemical Co., Ltd.] and 0.8 parts of organic peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexane 0.8 Parts are added with a double roll to homogenize, and this is compression molded for 10 minutes at a temperature of 170 ° C. and a pressure of 100 kg / cm ² to make a sheet with a thickness of 1 mm, and 200 ° C. for 4 hours in a hot air dryer. It heat-processed and produced the conductive silicone rubber base material.

Next, a kinematic viscosity consisting of 95 mol% of dimethylsiloxane units and 5 mol% of methylvinylsiloxane units was 10,000.
25 parts of acetylene black was added to 100 parts of cs methylvinylsiloxane, mixed with a gate mixer, and 0.1 part of isopropyl alcohol solution of chloroplatinic acid, 0.05 part of acetylene alcohol, and the formula Methylhydrogenpolysiloxane 1.1
Parts [SiH / Si (CH = CH ₂ ) ratio: 0.12] were added and mixed. Next, 100 parts of toluene was added to adjust the viscosity to a value convenient for coating, and this was coated on one side of a conductive silicone rubber substrate with a rod coater,
After air-drying for 10 minutes, heat at 200 ℃ for 10 minutes to obtain a thickness of 15
A conductive adhesive silicone rubber layer of 0 μm was provided.

When the initial adhesive force was measured by the same method as in Examples 1 and 2, it was 15 g / 20 mm, and it was well adhered to the skin. Also, this conductive adhesive silicone rubber structure was punched out into a circle with a diameter of 50 mm, stuck on a steel plate, and a copper electrode with a diameter of 10 mm was applied from above to measure the resistance between the electrodes with a digital multimeter. It was 1.5Ω. This proves that it can be used as a biomedical electrode.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the structure of the present invention in which an adhesive silicone rubber layer is provided on only one side of a silicone rubber base material. FIG. 2 is a cross-sectional view showing one embodiment of the structure of the present invention in which an adhesive silicone rubber layer is provided on both surfaces of a silicone rubber base material. FIG. 3 shows an embodiment of the structure of the present invention in the case where a silicone rubber base material reinforced with glass cloth is used as the silicone rubber base material and an adhesive silicone rubber layer is provided on only one surface. FIG.

Claims (1)

[Claims] 1. A silicone rubber substrate, and SiO provided on at least one surface of the silicone rubber substrate.
_From organopolysiloxanes that do not contain _4/2 units and have vinyl groups at the terminal and / or side chains, and organohydrogenpolysiloxanes that have two or more hydrogen atoms bonded to silicon atoms in a molecule, and platinum-based catalysts. And the molar ratio of the hydrogen atom bonded to the vinyl group to the silicon atom is 0.0
A tacky silicone rubber structure comprising a tacky silicone rubber layer obtained by curing a liquid or solution silicone rubber in the range of 2 to 0.8 by an addition reaction.