JP3031184B2 - Silicone rubber adhesive sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicone rubber pressure-sensitive adhesive sheet and a method for producing the same, and more particularly to a silicone rubber pressure-sensitive adhesive sheet having a polyethylene terephthalate film interposed between the silicone rubber sheet and a pressure-sensitive adhesive layer, and a method for producing the same.

[0002]

2. Description of the Related Art Silicone rubber sheets are excellent in heat resistance, electric insulation, chemical stability, cold resistance, compression set resistance, etc. Widely used for assembly and the like. An adhesive is often used for bonding the silicone rubber sheet, but an acrylic or rubber-based adhesive does not stick to silicone rubber, so a silicone-based adhesive is used. In some cases, a double-sided pressure-sensitive adhesive sheet is used, but a silicone-based pressure-sensitive adhesive layer is used on at least one side of the double-sided pressure-sensitive adhesive sheet to be adhered to the silicone rubber sheet.

An example in which the above double-sided pressure-sensitive adhesive sheet is used for a silicone rubber sheet will be described below. Silicone rubber adhesive tape is interposed between the glass of the display of a word processor, personal computer, etc. and the metal of the outer frame to prevent dust from entering and to provide cushioning between the metal and glass to prevent the glass from breaking due to impact. Let it. That is, a double-sided pressure-sensitive adhesive sheet having a core of a polyethylene terephthalate film or the like having good dimensional stability is attached to a silicone rubber sheet, and the obtained silicone rubber sheet with a double-sided pressure-sensitive adhesive sheet is finely cut into pieces of about 1 mm to about 1 mm. Silicone rubber adhesive tape with a width of 10 mm (the length during use depends on the size of the display, but is usually about 50 to 250 mm)
The tape is bonded by bonding the remaining pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet to the metal of the outer frame, and the glass of the display and the metal of the outer frame are aligned by joining the surfaces of the display glass and the silicone rubber layer of the tape. In general, a silicone rubber adhesive tape is interposed between them. In such a case, the reason why the silicone rubber is used as the material is that it is difficult to obtain the excellent physical properties as described above, particularly the excellent compression set resistance, using other materials. The use of a double-sided pressure-sensitive adhesive tape as described above is extremely easy to expand, especially when a thin tape is used, since silicone rubber generally has an elongation of 300% or more. This is because the use of a silicone rubber pressure-sensitive adhesive tape obtained by shredding a silicone rubber pressure-sensitive adhesive sheet is very difficult to determine the position to be pasted, because the tape stretches immediately when pulled slightly.

[0004]

However, when a double-sided pressure-sensitive adhesive sheet having a silicone-based pressure-sensitive adhesive layer on at least one side as described above is prepared and attached to a silicone rubber sheet, the step of preparing a double-sided pressure-sensitive adhesive sheet is performed. Since the number of steps is large, not only the number of steps is increased and the cost is increased, but also the silicone pressure-sensitive adhesive is expensive, which is economically disadvantageous. The present invention seeks to overcome the disadvantages of the prior art.

[0005]

According to the present invention, a separator, an adhesive layer, a polyethylene terephthalate film, a primer layer, a silicone rubber sheet, and, if necessary, a protective film are laminated in this order. A silicone rubber pressure-sensitive adhesive sheet is provided.

Further, according to the present invention, a primer solution is applied and dried on a polyethylene terephthalate film,
A step of forming a primer layer, laminating an unvulcanized silicone rubber kneaded composition sheet containing an unvulcanized silicone rubber and a crosslinking agent on the primer layer formed on the polyethylene terephthalate film, and applying pressure by a press A step of primary vulcanizing the unvulcanized silicone rubber kneaded composition sheet at a high temperature to form a laminate in which the polyethylene terephthalate film and the silicone rubber sheet are in close contact with each other. Vulcanizing, bonding and laminating together the surface of the polyethylene terephthalate film of the vulcanized laminate on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on a separator, furthermore, According to the method, it comprises a step of laminating a protective film on the silicone rubber sheet Method for producing a silicone rubber adhesive sheet is provided that.

Hereinafter, the present invention will be described in detail. The separator of the silicone rubber pressure-sensitive adhesive sheet of the present invention may be a normal separator obtained by applying a release agent to paper or a plastic film, and the pressure-sensitive adhesive layer may be a normal acrylic-based, rubber-based, silicone-based pressure-sensitive adhesive layer. Good, but slightly crosslinked or vulcanized ones that do not cause displacement are preferable, and
Acrylic is particularly preferred in terms of price and durability. The reason why the polyethylene terephthalate film was selected is that physical properties such as heat resistance and dimensional stability are good and that the price is reasonable.

[0008] The primer layer may be of any composition as long as it is interposed between the polyethylene terephthalate film and the silicone rubber sheet and adheres them to such an extent that they can be put to practical use.
It is preferably a mixture of a component that adheres to the polyethylene terephthalate film and a component that adheres to the silicone rubber sheet. Even in the case of such a mixture, in the method for producing a silicone rubber pressure-sensitive adhesive sheet of the present invention described later, at the stage of the primary vulcanization of the silicone rubber (if only the primary vulcanization is sufficient, the primary vulcanization is carried out by the primary vulcanization). If vulcanization and secondary vulcanization are performed, it is normal that good adhesion between the two cannot be ensured unless the primer layer and the silicone rubber sheet on the polyethylene terephthalate film are laminated at the primary vulcanization stage). . In the present specification, the expression "mixture" of the two components is employed, but depending on the case, the two components may react with each other, for example,
It is also conceivable that a component or the like that adheres to the silicone rubber sheet reacts with the silicone rubber.
It will be expressed as

As the component to be adhered to the polyethylene terephthalate film, a polyester resin soluble in an organic solvent is preferable, and examples thereof include a linear saturated polyester resin, a polyester resin obtained by internally plasticizing the same,
Examples thereof include urethane-modified polyester resins, epoxy-modified polyester resins, and acryl-modified polyester resins. Specific examples of these include "Vylon (trade name)" of various grades manufactured by Toyobo Co., Ltd. Preferred examples include "Byron 200",
Byron 103, Byron 240, Byron 300, Byron 500, Byron GK-13
0, "Byron GK-590", "Byron UR-1
200 "," Byron UR-2300 "," Byron E "
P-1012 "," Byron EP-1032 "," Byron BK-4101 ", and" Byron BK-4102 ". Needless to say, these polyester resins can be used as a mixture.

The silane coupling agent is preferably used as a component to be adhered to the silicone rubber sheet. In the silicone rubber pressure-sensitive adhesive sheet as a product, the functional groups may be, in some cases, both silicone rubber and the polyester resin. A reacted form is also conceivable. As a specific example of the silane coupling agent, γ- (2-aminoethyl)
Aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl)-
γ-aminopropyltrimethoxysilane hydrochloride, γ-
Glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ
-Anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-
Examples thereof include chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. In addition,
Needless to say, these silane coupling agents can be used as a mixed system.

The silicone rubber sheet is made of a vulcanized product of a general heat-curable silicone rubber having a siloxane bond as a main skeleton in a molecular structure. As the unvulcanized silicone rubber, for example, any of various grades of heat vulcanized silicone rubber manufactured by Dow Corning Toray Silicone Co., Ltd. may be used.
H841U "," SH851U "," SH861U ",
“SH35U”, “SH55UA”, “SH75U”
N "," SE4705U "," SE4706U "," S
E1185U ”,“ SE1186U ”,“ SE1187
U "," DY32-541U "," DY32-542 "
U "," DY32-903U "," DY32-904
U "," SH502UA & B "," SRX539U ",
“SE6770U-P”, “SE1602U”, “SR
X530U ”, and furthermore,“ SH745U ”,“ SH746U ”,“ S
H747U ". The crosslinking agent (= vulcanizing agent) to be added to the unvulcanized silicone rubber is, for example, various peroxides such as benzoyl peroxide. It is common to specify the agent,
The specified crosslinking agent may be used.

It is preferable to cover the silicone rubber sheet with a protective film in order to prevent dust and the like from adhering to the silicone rubber sheet. As the protective film, a plastic film such as a polyethylene film and a polypropylene film may be used, and the protective film of the plastic film can be weakly attached by wetting the surface of the silicone rubber sheet.

Next, a method for producing the silicone rubber pressure-sensitive adhesive sheet of the present invention will be described. First, preferably about 5 μm
To about 500 μm, more preferably about 10 μm to about 100
A primer layer is provided on one side of a μm polyethylene terephthalate film. For example, the polyester-based resin and the silane coupling agent are dissolved in various organic solvents such as toluene, xylene, methyl ethyl ketone, cyclohexanone, and ethyl acetate, or a mixed solvent thereof, and the obtained solution is subjected to the above polyethylene terephthalate film. On one side and dried, preferably about
01 μm to about 10 μm, more preferably about 0.1 μm to
A primer layer having a thickness of about 1 μm is formed. The mixing weight ratio of the polyester resin and the silane coupling agent depends on these types, and also on the type of silicone rubber, and furthermore, on the required practical adhesion between the polyethylene terephthalate film and the silicone rubber. Different, but generally from 1: 9 to 9: 1, preferably 3:
The mixing weight ratio is 7 to 7: 3.

Next, an unvulcanized silicone rubber kneaded composition sheet containing an unvulcanized silicone rubber and a crosslinking agent is laminated on the primer layer formed on the polyethylene terephthalate film and pressed (pressed). This is a step of primary vulcanizing the unvulcanized silicone rubber kneaded composition sheet at a high temperature under pressure. Unvulcanized silicone rubber and a crosslinking agent, and further, if necessary, a colorant, a filler, and other additives, for example, kneaded with a rubber kneading roll, preferably about 1 mm to about 500 mm, more preferably about 1 mm to about 500 mm. 2mm ~
It is expanded to a thickness of about 50 mm to obtain an unvulcanized silicone rubber kneaded composition sheet. This was weighed in a fixed amount, the unvulcanized silicone rubber kneaded composition sheet was placed on the primer layer on the polyethylene terephthalate film placed in a hydraulic press, and the press plate was pressed (pressed) from above. The primary vulcanization is performed by heating for a certain period of time while applying a pressure of 1 kg / cm ² to about 500 kg / cm ² , preferably about 2 kg / cm ² to about 300 kg / cm ² . In addition,
A polyethylene terephthalate film with a primer layer facing down on an unvulcanized silicone rubber kneading composition sheet placed in a hydraulic press machine can be similarly vulcanized and primary vulcanized. Since the order relation of the composition sheet, the primer layer, and the polyethylene terephthalate film is the same, in this specification, both aspects are treated as the same. Although the primary vulcanization temperature and the primary vulcanization time vary depending on the type of the heat-curable silicone rubber and the type of the crosslinking agent, the primary vulcanization temperature is generally 100 to 250 ° C, preferably 140 to 200 ° C.
At C, the primary vulcanization time is generally between 3 minutes and 4 hours, preferably between 5 minutes and 1 hour. If the heat-curable silicone rubber is of a grade that does not require secondary vulcanization, the vulcanization step can be completed only with this primary vulcanization.

Next, when performing secondary vulcanization, heat vulcanization is continued without pressing (pressing), and in some cases, a product generated from a crosslinking agent (for example, when benzoyl peroxide is used as a crosslinking agent, Scatters benzoic acid)
Complete vulcanization and ensure the desired physical properties of the silicone rubber. Although the secondary vulcanization temperature and the secondary vulcanization time vary depending on the type of the heat-curable silicone rubber and the crosslinking agent, the secondary vulcanization temperature is generally 150 to 300 ° C, preferably 170 to 300 ° C.
At 250 ° C., the secondary vulcanization time is generally 30 minutes to 10 minutes.
Time, preferably 1 hour to 6 hours. As described above, the thickness of the silicone rubber sheet layer that has been completely vulcanized by performing only the primary vulcanization or the secondary vulcanization is preferably 0.1%.
mm to 20 mm, more preferably 0.2 mm to 5 mm. The adhesive strength between the silicone rubber sheet and the polyethylene terephthalate film obtained in this manner varies depending on the application, but it is generally sufficient for practical use to be about 100 g / 25 mm or more in a measuring method according to JIS Z1529. .

In the next step, the surface of the polyethylene terephthalate film of the vulcanized laminate is adhered and laminated (transferred) on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on a separator. This is the step of performing First, a pressure-sensitive adhesive solution or a pressure-sensitive adhesive emulsion is prepared, applied to a separator, and dried to prepare the pressure-sensitive adhesive sheet. The thickness of the pressure-sensitive adhesive layer is preferably 2 μm to 50 μm.
0 μm, more preferably 4 μm to 50 μm. This is used as a target silicone rubber adhesive sheet as described above by a so-called transfer method. In addition, a plastic film such as a polyethylene film or a polypropylene film of 5 μm to 30 μm, for example, is used as a protective film to cover the surface of the silicone rubber sheet by utilizing the wetting of the silicone cone surface, and dust and the like are deposited on the silicone rubber surface. You may prevent it from adhering.

The silicone rubber pressure-sensitive adhesive sheet thus obtained is used after being cut into a tape having an appropriate width or another appropriate shape according to the intended use. For example, when used as a silicone rubber adhesive tape sandwiched between a glass of a display of a word processor, a personal computer, and the like and a metal of an outer frame described in the section of “Prior Art”, it is finely cut into a width of about 1 mm to about 5 mm ( The length at the time of use is adjusted to the size of the display, but it is usually about 50 to 250 mm).

[0018]

[Function] At least one side has a silicone pressure-sensitive adhesive layer,
A double-sided pressure-sensitive adhesive sheet using a plastic film such as a polyethylene terephthalate film as a core is prepared, and the double-sided pressure-sensitive adhesive sheet is compared with a conventional technique in which the double-sided pressure-sensitive adhesive sheet is bonded and laminated to a silicone rubber sheet via the silicone pressure-sensitive adhesive layer. According to the present invention, a polyethylene terephthalate film is directly adhered to a silicone rubber sheet via a primer layer by an integral molding method, and is adhered to an adherend using an adhesive layer provided on a surface of the polyethylene terephthalate film by a transfer method. Since it can be used after being worn, the total number of steps can be reduced, and in many cases, an expensive silicone-based pressure-sensitive adhesive does not need to be used, so that significant cost reduction can be achieved.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to Examples.

Example 1 A polyester resin "Byron 20" manufactured by Toyobo Co., Ltd.
0 "and γ-chloropropylmethyldimethoxysilane as a silane coupling agent were dissolved in a mixed solvent of methyl ethyl ketone and toluene at a solid content weight ratio of 1: 1 to prepare a primer solution. This solution was applied on one side of a polyethylene terephthalate film having a thickness of about 50 μm to a dry thickness of about 0.5 μm and dried to form a primer layer.

[0021] placed in a hydraulic press and the port triethylene terephthalate film a primer layer thereon, superimposed unvulcanized silicone rubber kneaded composition sheet of approximately 5mm thickness thereon. This unvulcanized silicone rubber kneaded composition sheet is applied to a heat vulcanizable silicone rubber “SH502UA & B” manufactured by Dow Corning Toray Silicone Co., Ltd. and a vulcanizing agent (= crosslinking agent) “RC-4 (50p)” manufactured by the company. FD "at a weight mixing ratio of 100: 1, kneaded with a rubber kneading roll, and spread into a sheet. Next, a press plate is pressed from above the unvulcanized silicone rubber kneaded composition sheet, and under a pressure of about 100 kg / cm ² at about 170 ° C. for about 1 hour.
Heating was performed for 0 minutes to perform primary vulcanization of the unvulcanized silicone rubber.

Next, the press plate was removed, and heating was continued at about 200 ° C. for about 3 hours without pressing (pressing) the silicone rubber to perform secondary vulcanization, thereby completing the vulcanization of the silicone rubber. . Thus, a sheet having a silicone rubber layer thickness of about 0.7 mm was prepared.

On the paper separator, an organic solvent solution of an acrylic pressure-sensitive adhesive was applied and dried to form a pressure-sensitive adhesive layer having a thickness of about 20 μm. Note that the acrylic pressure-sensitive adhesive was slightly cross-linked to prevent slippage. This pressure-sensitive adhesive layer and the surface of the polyethylene terephthalate film of the above sheet were overlapped to prepare a silicone rubber pressure-sensitive adhesive sheet. About 5 μm on the silicone rubber layer of this silicone rubber adhesive sheet
A polyethylene film having a thickness was stacked and pressed, and a polyethylene film as a protective film was adhered by wetting the silicone rubber layer.

This silicone rubber pressure-sensitive adhesive sheet with a protective film was finely cut into a width of about 2 mm, the protective film and the separator were peeled off, and the mixture was strongly rubbed. It was able to withstand the purpose of interposing a cushion material between the glass of the display of the personal computer and the metal of the outer frame as described in the section of the related art. In the measurement of the adhesive strength between the polyethylene terephthalate film layer and the silicone rubber layer according to JIS Z1529, the adhesive strength exceeded about 200 g / 25 mm.

[0025]

According to the present invention, a double-sided pressure-sensitive adhesive sheet having a silicone pressure-sensitive adhesive layer on at least one side and a plastic film such as a polyethylene terephthalate film as a core is prepared, and the double-sided pressure-sensitive adhesive sheet is applied to a silicone rubber sheet. According to the present invention, a polyethylene terephthalate film is directly adhered to a silicone rubber sheet via a primer layer by an integral molding method, compared to a conventional technique used by sticking and laminating through a polyethylene terephthalate film. Since it can be used by attaching it to an adherend using the pressure-sensitive adhesive layer provided by the transfer method, the total number of steps can be reduced, and in some cases, it is not necessary to use an expensive silicone-based pressure-sensitive adhesive. Many can achieve significant cost savings. Since the silicone rubber pressure-sensitive adhesive sheet of the present invention uses a polyethylene terephthalate film having good dimensional stability as the core, it is easy to determine the position to be stuck without stretching, especially when used as a tape after shredding. It is. The silicone rubber pressure-sensitive adhesive sheet of the present invention can be used not only as a cushion material for various applications, but also for various heat-resistant packings, by utilizing the above-mentioned various excellent physical properties of silicone rubber, particularly, excellent compression set resistance. It is expected that it can be used for heat dissipation sheets, insulating tapes and other various applications.

Claims (4)

(57) [Claims] 1. A separator, the pressure-sensitive adhesive layer, a polyethylene terephthalate film, a primer layer, the silicone rubber adhesive sheet characterized by being laminated in this order of the silicone rubber sheet. 2. The silicone rubber pressure-sensitive adhesive sheet according to claim 1, wherein the primer layer is composed of a mixture of an ester resin and a silane coupling agent. 3. A step of applying and drying a primer solution on a polyethylene terephthalate film to form a primer layer, comprising an unvulcanized silicone rubber and a crosslinking agent on the primer layer formed on the polyethylene terephthalate film. The unvulcanized silicone rubber kneaded composition sheet to be laminated is laminated, and the unvulcanized silicone rubber kneaded composition sheet is first vulcanized at a high temperature under pressure by a press to form a laminate in which the polyethylene terephthalate film and the silicone rubber sheet adhere to each other. process involving the more the polyethylene terephthalate Engineering of sticking-layered combined surface of phthalate film of said laminate which was completed vulcanized on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having an adhesive layer on the cell Pareta forming A method for producing a silicone rubber pressure-sensitive adhesive sheet. 4. A method for producing a silicone rubber pressure-sensitive adhesive sheet, wherein the primer liquid is a solution in which an ester resin and a silane coupling agent are dissolved in a solvent.