JP2002144484A - Cushioning material having mold release characteristics and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cushioning material having mold release characteristics which has sufficient mold release characteristics and elasticity, and can withstand repeated use. SOLUTION: A crosslinked fluororubber surface layer is composed by crosslinking a fluororubber containing a fluoroplastic powder wherein the fluoroplastic powder partially exposed on the surface. The cushioning material having mold release characteristics is formed by covering at least one face of a fluororubber molded body with the crosslinked fluororubber surface layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushioning material having releasability, in particular, a releasable cushioning material suitable for a cushioning material used in a bonding step at the time of manufacturing a flexible printed circuit board, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Flexible printed circuit boards (hereinafter referred to as F)
PC (abbreviated as PC) is a thin, light, flexible, and precise wiring-capable film substrate. With the advent of various small appliances, the demand has been greatly increased. A typical FPC has a structure in which a metal foil circuit pattern is provided on a resin film of polyimide or the like, and a resin coverlay film for separating a conductive portion from an insulating portion is further provided thereon. ing. In addition, depending on the FPC, a reinforcing base material is bonded to a portion where reinforcement is required.

[0003] Here, the bonding of the coverlay film and the reinforcing substrate is performed by pressure bonding to the FPC via an epoxy adhesive or the like. In this step, a method such as hot pressing is used to sufficiently cure the adhesive. At that time, a cushioning material is used to completely absorb the unevenness of the circuit pattern and the reinforcing base material and perform the bonding.
A release film is disposed between the and the cushion material for the purpose of preventing the adhesive from sticking. As the cushion material, a fiber-reinforced silicone rubber sheet or the like is used, and as the release film, a film such as an ethylene / tetrafluoroethylene copolymer (ETFE) or a polymethylpentene resin (TPX) is used.

[0004]

However, since the above-mentioned releasable film is provided with unevenness of the FPC every time the pressure is applied, it has to be disposable once. Further, the silicone rubber sheet as the cushioning material has excellent heat resistance and resilience, but has insufficient strength, and therefore has a defect of generating cracks and cracks during hot pressing. Even if reinforced with fiber etc. to improve this point, peeling between fiber and rubber occurs at the time of pressing, which causes the difference in cushion thickness for each part,
Further, there may be a case where the adhesion of the FPC is poor. fiber
-Peeling between the rubbers also causes the cushioning material itself to break when the press is repeated. Therefore, at present, the silicone rubber cushion material is also discarded after several uses. Therefore, there is a demand for a release film and a cushioning material which are excellent in strength such as releasability, resilience, heat resistance and compression resistance and can withstand repeated use.

[0005] As a rubber having heat resistance higher than that of silicone rubber and capable of exhibiting high strength, fluorine rubber is cited.
However, fluororubber has a high affinity with epoxy resin and the like, and the adhesive is firmly stuck, so that it cannot be used without a release film. Even when a release film is used, the cushion material and the release film may partially adhere to each other, resulting in extremely poor workability.

[0006] As a method for imparting mold releasability to rubber, 1) a method in which oil is mixed into rubber, 2) a method in which a crosslinking agent is impregnated in the vicinity of the surface of a rubber material and heated to increase the crosslinking density in the vicinity of the surface. (See Japanese Patent Publication No. 5-1931, etc.), 3) a method of blending silicone rubber (see Japanese Patent Application Laid-Open No. 5-339456, etc.),
There are known 4) a method of coating the surface of a rubber material with a resin or the like, and 5) a method of filling a powder of a fluororesin or the like into rubber.

However, in the method 1), since the fluororubber has low compatibility with the hydrocarbon oil and the silicone oil, problems such as contamination of the FPC due to leaching of the oil and reduction in the strength of the cushion material itself are caused. According to the method 2), a certain degree of releasability can be imparted, but as shown in the examples described later, the effect is not satisfactory. In the method of 3), the releasability is not sufficiently given,
There are disadvantages such as a decrease in the strength of the fluoro rubber cushion material. In addition, the method 4) has problems such as detachment of the resin layer and reduction in rubber elasticity due to the presence of the resin layer. In this regard, for example, as described in Japanese Patent Application Laid-Open No. 1-141909, a technique of combining a resin such as a curable polyester with a coupling agent such as silyl isocyanate to prevent detachment of a resin surface layer is also proposed. Have been. However,
As shown in Examples below, even if the surface of the fluororubber material is treated with a resin solution containing silyl isocyanate, the releasability that can withstand repeated use is not exhibited. In the simple filling method as described in 5) (see Patent No. 3009676, etc.), the amount of resin powder appearing in the surface layer is small, and sufficient releasability is not exhibited. To solve this problem, increase the resin powder loading,
Problems such as a decrease in the elasticity and strength of the rubber material and a deterioration in cross-linking moldability occur.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a releasable cushion material which has both sufficient releasability and elasticity, and can withstand repeated use.

[0009]

Means for Solving the Problems We have repeatedly studied to solve the above problems and found that it is effective to form a surface layer made of crosslinked fluororubber containing fluororesin powder on a fluororubber molded article. Was found.

[0010] That is, the present invention provides A) a crosslinked fluororubber surface layer comprising a crosslinked fluororubber containing a fluororesin powder, and a part of the fluororesin powder being exposed on the surface; Is provided on at least one surface thereof.
Further, the present invention, C) on one or both sides of the metal plate, B ') fluororubber sheet is laminated, B') the surface of the fluororubber sheet, A) crosslink the fluororubber containing the fluororesin powder. The present invention provides a releasable cushion material characterized in that it is covered with a crosslinked fluororubber surface layer on the surface of which a part of the fluororesin powder is exposed.

According to the present invention, there is also provided a cushion material used for bonding a substrate to a coverlay film or a reinforcing substrate in the manufacture of a flexible printed circuit board, comprising the above-mentioned releasable cushion material. The present invention provides a cushioning material for manufacturing a flexible printed circuit, characterized in that:

In the present invention, a liquid material containing a fluororesin powder, an uncrosslinked fluororubber, a crosslinking agent for a fluororubber and a solvent is further applied to the surface of the fluororubber molded article, and after the solvent is removed by drying, Provided is a method for producing a releasable cushion material, wherein a non-crosslinked fluororubber is crosslinked at a temperature of 300 ° C. for 1 minute to 50 hours.

Here, it is an important requirement of the present invention to form the surface layer of the cushioning material with the fluororesin powder together with the fluororubber. As will be shown in Examples described later, even if a fluororesin powder is filled in a fluororubber and molded into a sheet, satisfactory release properties cannot be obtained and the strength is reduced. Further, even if the surface of the fluororubber is treated with a commercially available surface treating agent, good releasability is not necessarily exhibited. On the other hand, according to the present invention, when the fluororubber molded article is coated with a crosslinked fluororubber surface layer containing a fluororesin powder, good releasability is exhibited and maintained, and the elasticity is ensured by the fluororubber molded article. A releasable cushion material having excellent strength such as compression resistance can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, any of A) a crosslinked fluororubber surface layer containing a fluororesin powder (hereinafter, simply referred to as a "surface layer") and B) a fluororubber molded article are used as the raw material fluororubber. Can be used, and there is no particular limitation on the type. As an example, hexafluoropropylene / vinylidene fluoride binary copolymer (for example, Viton A, Sumitomo 3M manufactured by Showa Denko DuPont)
Co., Ltd. Florel, Daikin Industries Co., Ltd.
Technofluorone manufactured by Ausimont Co., Ltd.), terpolymer of tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride (for example, Viton B manufactured by Showa Denko DuPont, Florel manufactured by Sumitomo 3M Co., Ltd., Daikin Industries, Ltd.) (stock)
Made by Audimont, etc.)
Copolymers mainly composed of tetrafluoroethylene / propylene (for example, Aflas manufactured by Asahi Glass Co., Ltd./Nippon Synthetic Rubber Co., Ltd.), pentafluoropropylene / vinylidene fluoride binary copolymer, chlorotrifluoroethylene / fluorocarbon Vinylidene fluoride copolymer, polymer having a perfluoroalkoxy group (for example, Technoflon P manufactured by Audimont Co., Ltd.)
7) and fluorosilicone rubber (for example, Silastic LS manufactured by Dow Corning), but are not limited thereto, and any rubber having a fluorine atom in the molecule may be used. be able to. It is also possible to use a plurality of fluororubbers in combination. A)
The raw material rubber of the surface layer, B) the fluororubber molded article, may not be the same.

However, in the present invention, it is preferable to use a fluororubber whose main chain is composed of carbon atoms and does not contain chlorine atoms. More preferably,
A binary or ternary fluororubber having a vinylidene fluoride unit as a constituent unit is used. In particular, when the ternary fluororubber is used for the fluororubber surface layer A), the releasable cushioning material of the present invention can be made more excellent in releasability and chemical resistance. In addition, by using a binary fluororubber for the B) fluororubber molded product, a compression set with a small compression set and a more excellent resilience can be obtained.

B) The fluororubber molded article can be obtained by crosslinking and molding the above raw material fluororubber with a crosslinking agent such as polyol, polyamine, peroxide or the like. Examples of crosslinking agents include polyol crosslinking agents such as, for example, bisphenol AF, bisphenol A, p, p'-biphenol, 4,4'-dihydroxydiphenylmethane, hydroquinone, dihydroxybenzophenone, and alkali metal salts thereof; for example, hexamethylenediamine carbamate (Diak N from DuPont)
o.1), ethylenediamine carbamate (commercially available under the trademark Diak No. 2 from DuPont), N, N'-dicinamylidene-1,6-hexanediamine (commercially available from DuPont under the trademark Diak No.3), N, N'-bis (o-methoxybenzylidene) -1,6-hexanediamine, N, N'-bis (p-methoxybenzylidene) -1,6- Xylenediamine, N, N'-bis (o-hydroxybenzylidene) -1,6-hexylenediamine, N, N'-
Bis (N, N'-dimethyl-p-aminobenzylidene) -1,6-
Polyamine crosslinking agents such as hexylenediamine, 4,4'-bis (aminocyclohexyl) methane carbamate; for example, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 1,1-di (t-butyl) Peroxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-
2.5-di (t-butylperoxy) hexane, 2,5-dimethyl
-2.5-di (t-butylperoxy) hexyne-3,1,3-di (t
-Butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropylcarbonate, n-butyl-
4,4-di (t-butylperoxy) valerate, α, α′-bis (t-butylperoxy-m-isopropyl) benzene,
Examples include, but are not limited to, peroxide crosslinking agents such as benzoyl peroxide.

However, in the present invention, it is preferable that the fluororubber molded article B) is crosslinked with a polyol or a peroxide. These crosslinked systems have a smaller permanent compression set than polyamine crosslinked products and are excellent as releasable cushioning materials. Particularly preferably, a polyol crosslinking agent is used. This makes it more difficult for A) the fluororesin particle-containing crosslinked rubber surface layer to peel off, and the releasability is exhibited over a long period of time.

At the time of crosslinking, it is preferable to use a crosslinking accelerator, an auxiliary and the like in combination. In the case of polyol crosslinking or polyamine crosslinking, magnesium oxide (MgO), calcium hydroxide (Ca (OH) 2), calcium oxide (CaO), lead oxide
An acid acceptor such as (PbO) is essential. Particularly in polyol crosslinking, a crosslinking accelerator such as an organic phosphonium salt such as benzyltriphenylphosphinium chloride, a quaternary ammonium salt such as tetrabutylammonium chloride, DBU (1,8-diazabicyclo [5.4.0] -7) -Undecene), and a tertiary amine such as hexamethylenetetramine is preferably used in combination.

The amounts of the cross-linking agent and the cross-linking accelerating (auxiliary) agent and the cross-linking method are not particularly limited, and those skilled in the art can arbitrarily determine them according to the intended physical properties and the type of the cross-linking (promoting) agent. I can do it. For example, about 0.1 to 10 parts by weight of a polyol, about 10 parts by weight or less of a crosslinking accelerator, about 1 to 20 parts by weight of magnesium oxide, and about 0 to 10 parts by weight of hydroxylation with respect to 100 parts by weight of a fluororubber. By mixing calcium and heating at a temperature of about 100 to 300 ° C. for 1 minute to 100 hours, a crosslinked product can be obtained. As a heating method, a method such as hot pressing or hot air can be employed, but is not limited thereto. A crosslinking method using radiation or the like may be used. The method of crosslinking fluororubber is well known, and those skilled in the art will easily obtain a desired molded product.

In addition to the above, various known compounds such as carbon black, graphite, reinforcing fibers, processing aids, softeners and coupling agents can be blended into the fluororubber molded article B). Particularly, MT-carbon, FT-carbon, SR
It is preferable to mix 5 to 50 parts by weight of carbon black such as F-carbon with respect to 100 parts by weight of rubber. This makes it possible to further improve the heat compressibility of the release cushion material.

A) As the fluororesin powder in the surface layer, powders of various known fluororesins can be used. Examples include tetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyvinylidene fluoride (PVd
F), polyvinyl fluoride, chlorotrifluoroethylene,
Ethylene / chlorotrifluoroethylene copolymer (ECT
FE), ethylene / tetrafluoroethylene copolymer (ET
FE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride terpolymer (TH
V) and the like, but are not limited thereto. It is also possible to use a plurality of types of fluororesin powder in combination.

However, in the present invention, it is preferable to use any one of PTFE, PFA, FEP and ETFE as the fluororesin powder. Particularly preferably, PTFE powder is used. With this, it is possible to obtain a more excellent releasability. PTFE powder is commercially available, for example, from Daikin Industries, Ltd. under the trademark Polyflon TFE or Rubron, and from Asahi Glass Co., Ltd., under the trademark Fluon. Radiation-crosslinked PTFE powder may be used. Crosslinked PTFE powder is commercially available, for example, from Hitachi Cable, Ltd. under the trademark XF-0.

The particle size of the fluororesin powder is not particularly limited, but is preferably 0.1 to 100 μm, more preferably 0.2 to 50 μm, and particularly preferably 0.5 to 20 μm. If the particle size is large, A) the fluororesin powder is easily detached from the surface layer, which adversely affects the release property. If the particle size is too small, not only does the fluororesin powder agglomerate and handling becomes difficult, but also A) the dispersibility of the fluororesin powder in the surface layer deteriorates, resulting in uneven release properties.

A) The surface layer is composed of the above-mentioned fluororesin powder and fluororubber. There is no particular limitation on the ratio of both, but it is preferable to add about 50 to 250 parts by weight, particularly 100 to 200 parts by weight, of the fluororesin powder to 100 parts by weight of the fluororubber in the surface layer. If the amount of the fluororesin powder is small, the amount of the fluororesin powder exposed on the surface is reduced, and it is difficult to exhibit the releasability. If the amount is too large, it is difficult to form the surface layer.

The fluororubber in the surface layer (A) may be crosslinked by any method, but it is preferable to crosslink the polyol (B) as in the case of the fluororubber molded article. Thereby, A) the surface layer can be cross-linked by hot air, and the production method of the releasable cushion material can be set more freely. The type and amount of the crosslinking agent, the accelerator, etc., may be the same or different as in the B) fluororubber molded article,
It is preferable to use the general formulation exemplified above.

A) Graphite and / or carbon black may be further added to the surface layer in an amount of 10 to 100 parts by weight based on 100 parts by weight of the fluororubber in the surface layer A). Preferably, about 10 to 150 parts by weight, particularly about 20 to 100 parts by weight, of MT-carbon, FT-carbon, SRF-carbon and the like are used. As a result, A) the releasability of the surface layer can be further enhanced, and the mechanical strength is greatly improved.

In order to further improve the releasability of the cushioning material, a terpolymer of tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride having a specific gravity of 1.90 to 1.95 is prepared by: It can also be contained therein.
The terpolymer of tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride having the above specific gravity is known per se. For example, THV200G and THV200P are available from Sumitomo 3M.
It is commercially available under the trademark. This polymer has the same type of constituent units as the tertiary fluororubber, but has a lower molar ratio of vinylidene fluoride units than the fluororubber. Therefore, the specific gravity is as high as about 1.90 or more (about 1.85 to 1.88 in the case of a ternary fluororubber), and the polymer is close to PTFE in physical properties such as strength and releasability. On the other hand, unlike PTFE, since it is soluble in solvents such as THF, ketone, and ester, it can be kneaded with fluororubber in the form of a solution. Co-crosslinking with fluororubber is also possible. The compounding amount of the terpolymer is as follows: A) Fluoro rubber 100 in the surface layer
About 500 parts by weight or less, especially 10 to 300 parts by weight
It is preferable to use about parts by weight.

A) In addition to the above, a plasticizer such as dioctyl phthalate, a processing aid, a coupling agent and the like may be added to the surface layer.

The method of coating the above B) fluororubber molded article with the surface layer A) is optional. For example, the mold release of the present invention is performed by preforming the molded article B), A) a film made of a prepolymer of fluororubber containing the fluororesin powder of the surface layer, a sheet, and the like, and pressing and heating. It can be used as a cushioning material. Alternatively, both may be simultaneously extruded and crosslinked with hot air or the like.

However, the releasable cushion material of the present invention is obtained by applying a liquid containing a fluororesin powder, uncrosslinked fluororubber, a crosslinking agent for fluororubber and a solvent to the surface of the fluororubber molded article B), After drying and removing, it is preferable to maintain the temperature at 100 to 300 ° C. for 1 minute to 50 hours to crosslink the uncrosslinked fluororubber to produce. By using a liquid material, B) the fluororubber molded article, and thus the releasable cushion material, can be formed into a desired shape.

In the releasable cushioning material of the present invention, it is preferable that the surface layer A) is not too thick from the viewpoint of mechanical strength such as cushioning property and heat-resistant compression property. A) The thickness of the surface layer is preferably about 1 to 500 μm, more preferably about 2 to 200 μm, and particularly preferably 5 to 10 μm.
It is about 0 μm. In forming such a thin surface layer, it is easiest to apply a fluororesin powder, uncrosslinked fluororubber, a crosslinking agent for fluororubber, etc. to a liquid using a solvent, and B) apply it onto a fluororubber molded article. It is.

As the solvent, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, which are good solvents for fluororubber; ethyl acetate, propyl acetate;
Ester solvents such as butyl acetate; THF, dioxane and the like are preferable. The solubility may be adjusted by adding a small amount of toluene, methanol, ethanol or the like. The amount of these solvents used is not particularly limited, but is preferably set so that the solid content concentration is about 5 to 90% by weight, particularly about 10 to 70% by weight, from the viewpoint of workability. The liquid thus produced can be applied to one or both sides of a B) fluororubber molded article, for example, a sheet by any conventional method such as roll coating, brushing, spraying, dipping, and the like. After applying this liquid material, the solvent is dried and removed, and heat treatment is performed under the above conditions, whereby A) a surface layer is formed.

The degree of cross-linking of B) the fluororubber molded article at the time of A) coating the fluororubber molded article with the surface layer is arbitrary. For the purpose of increasing the size system of the release cushion material
It is preferable that B) the fluororubber molded article is highly crosslinked, and A) the crosslinking degree of the fluororubber molded article is low for the purpose of increasing the fixation degree of the surface layer. Also,
B) As a fluororubber molded article, an uncrosslinked pre-molded article can also be used.

The releasable cushioning material of the present invention also comprises C) a B ') fluororubber sheet laminated on one or both sides of a metal plate, and B') a fluororubber sheet surface coated with A) surface layer. Structure may be used. By forming a laminate with a metal, the handleability of the releasable cushioning material is improved, and there is an advantage that the FPC bonding step can be automated.

C) The thickness of the metal plate is arbitrary, but is preferably about 0.05 to 1 mm, more preferably about 0.1 to 0.5 mm.
And The type of the metal plate is not particularly limited, and a desired metal plate such as a steel plate, a stainless steel plate, and an aluminum plate can be used.

C) The method of laminating B ') the fluororubber sheet on the metal plate is not particularly limited. For example, C) a metal plate and an uncrosslinked fluororubber may be vulcanized and bonded in a mold, or a crosslinked B ′) fluororubber sheet may be bonded to the C) metal plate with an adhesive or the like. . Furthermore, a laminate can be obtained by making the uncrosslinked fluororubber liquid with a solvent, C) applying it on a metal plate, drying and optionally crosslinking. As the type of the solvent, and the conditions for drying and crosslinking, the same ones as in the case of A) forming the surface layer can be selected. In addition, it is preferable that C) a metal plate is previously subjected to a treatment such as sandblasting or primer application.

C) Metal plate made by any of the above methods /
B ′) A) A surface layer is formed on the laminate of the fluororubber sheet in the same manner as described above. Incidentally, by laminating both the B ′) fluororubber sheet and the A) surface layer in the form of a liquid material, it is possible to automate the production process of the release cushion material.

Since the releasable cushioning material of the present invention has excellent releasability, it can be used as a thermosetting adhesive, a hot melt adhesive, an emulsion adhesive, for example, an epoxy adhesive, an acrylic adhesive, a polyurethane adhesive. Adhesives, silicone adhesives, phenolic resin adhesives, polyimide adhesives, polyamide adhesives, polyvinyl acetate adhesives, ethylene
-Vinyl acetate copolymer adhesive, vinyl chloride adhesive,
Furthermore, it can be used at a site where rubber latex adhesive such as NR, NBR, SBR, IIR, CR, etc. directly contacts. Also, since it is based on fluororubber, it has excellent mechanical strength, resilience, heat resistance and the like. Therefore, it can withstand use in a part pressed at a high temperature, such as a hot press or a hot roll. In particular, it is suitable for use as a cushion material in a step of bonding a coverlay or a reinforcing plate to an FPC board.

[0040]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

[Examples 1 to 6] 100 parts by weight of technoflon NM (a binary fluoro rubber manufactured by Ausimont Co.)
200 parts by weight of FE powder (Polyflon TFE M-12 manufactured by Daikin Industries, Ltd., particle size 25 μm), 50 parts by weight of SRF-carbon (Asahi # 50 manufactured by Asahi Carbon Co., Ltd.), 3 parts by weight of calcium hydroxide, oxidation 3 parts by weight of magnesium, 2 parts by weight of DBU, and 3 parts by weight of bisphenol AF are blended, and propyl acetate 400
A liquid was prepared by adding parts by weight.

Separately from the above, the following various raw rubber 100
SRF-Carbon (Asahi Carbon Co., Ltd. Asahi # 50) 5
0 parts by weight, 3 parts by weight of calcium hydroxide, 3 parts by weight of magnesium oxide, 2 parts by weight of DBU, and 3 parts by weight of bisphenol AF were kneaded using a rubber kneading roll. The obtained compounded rubber was placed in a mold, and crosslinked and formed into a sheet of 300 × 150 × 2 mm by a hot press. Viton A, Binary fluoro rubber manufactured by Dupont Dow Elastomer Co., Ltd. Viton B, Ternary fluoro rubber FLOREL FLS-2650 manufactured by Dupont Dow Elastomer Co., Ltd. Binary fluoro rubber manufactured by Sumitomo 3M Co., Ltd. Technoflon NH, Ausimont Binary fluororubber technoflon NMR, Audimont binary fluororubber technoflon NM, Audimont binary fluororubber

The above liquid material was applied to each of the obtained rubber sheets by a hand roll, and a fluororesin-containing layer having a dry thickness of 50 to 70 μm was provided. Put this in an oven at 70 ° C for 1
After drying with hot air for hours, the temperature was kept at 230 ° C. for 4 hours.

Each of the rubber sheets provided with the surface layer as described above was subjected to an adhesion test and a tensile test. Tensile test is 3
No. dumbbell was used in accordance with JIS K6251. Moreover, the adhesion test performed the tensile shear test according to JISK6854.

That is, 150 × 2
A 5 mm strip test piece was punched out, an adhesive was applied to a portion of 12.5 × 25 mm from the end of the surface provided with the surface layer, and then overlapped with the surface layer application surface of another similarly prepared test piece. Together, the adhesive was cured to obtain a measurement sample. Yuka Shell Epoxy Co. Epicoat 828 /
Cured for 2 hours at 100 ° C. using EpiCure EMI24 mixture (100/4). This test measures the adhesive strength, but this time, in addition to this, among the measurement samples (5 bodies), the ratio of the release properties on the bonding surface without breaking was calculated as the "peeling rate", It was used as an index of releasability together with the adhesive strength. In addition, the test piece which was peeled but had a crack in a part of the test piece was 0.5
Calculated as body. In addition, for samples with good mold release properties, after the adhesion test, peel off the epoxy resin at the bonding part,
After washing with ethanol, another adhesion test was performed.

The test results are shown in Table 1. It is clear that the releasable cushion material of each of the examples according to the present invention exhibits excellent releasability while maintaining sufficient strength. A pressure of 100 kgf / cm ² at 180 ° C. was applied to the rubber sheet of Example 6 for 5 times.
No cracks or cracks were generated even after minutes. When this pressing operation was repeated 5 times at intervals of 5 minutes, no cracks or cracks were observed even after the fifth pressing.

[Comparative Examples 1 and 2] Tecnoflon NM100
15 parts by weight of PTFE powder (Polyflon TFE M-12 manufactured by Daikin Industries, Ltd., average particle size 25 μm) in parts by weight (Comparative Example 1)
Or 50 (Comparative Example 2) parts by weight, SRF-carbon (Asahi Carbon Co., Ltd. Asahi # 50) 20 parts by weight, calcium hydroxide 3 parts by weight, magnesium oxide 3 parts by weight, DBU 2 parts by weight, bisphenol AF 3 parts by weight It was compounded and kneaded using a rubber kneading roll. After disposing the obtained compounded rubber in a mold and cross-linking it into a 300 x 150 x 2 mm sheet by hot pressing,
The temperature was kept at 230 ° C. in an oven for 4 hours.

The rubber sheet obtained had bubbles in some places. This is presumably because the PTFE powder was partially agglomerated and degassing at the start of crosslinking was not successful.
About these rubber sheets, similarly to Example 6, 180 degreeC
When a pressure test was conducted in which a pressure of 100 kgf / cm ² was applied for 5 minutes, all sheets were broken at one time. Further, the same adhesion test and tensile test as those in Examples 1 to 6 were performed on these rubber sheets.

The results are shown in Table 1. Unlike the releasable cushioning materials of the examples, in all of these rubber sheet cushioning materials, the rubber was broken before peeling in the first adhesion test, and It is clear that the properties are insufficient.
Further, in Example 6 not only in terms of compression resistance but also in terms of tensile strength.
It shows a lower value, indicating that the strength is inferior.

[0050]

[Table 1]

[Examples 7 to 11, Comparative Examples 3 to 5] Binary fluororubber (Florel FC-2145 manufactured by Sumitomo 3M Co., Ltd.)
100 parts by weight, 30 parts by weight of MT-carbon (Thermax N990 manufactured by Cancarb), 5 parts by weight of magnesium oxide,
VC20 (Dupont Dow Elastomer Co., Ltd. crosslinking accelerator)
2 parts by weight and 4 parts by weight of VC30 (a cross-linking agent manufactured by DuPont Dow Elastomer Co., Ltd.) were mixed and kneaded using a rubber kneading roll. The obtained compounded rubber was placed in a mold, and cross-linked into a sheet of 300 × 150 × 2 mm under the condition of 200 ° C. × 12 minutes using a hot press, and then heated to a temperature of 200 ° C. in an oven for 20 hours. Held.

Each of the rubber sheets obtained above was applied with each of the liquid materials having the composition shown in Table 2, and was placed in an oven at 70 ° C. × 3.
After drying with hot air for 0 minutes, baking was performed under the conditions shown in Table 2.
The raw materials described in Table 2 are as follows. M-111: PTFE powder manufactured by Daikin Industries, Ltd., average particle diameter 33 μm M-137: PTFE powder manufactured by Daikin Industries, Ltd., average particle diameter 400 μm AT-No. 15: Graphite manufactured by Oriental Sangyo Co., Ltd. Powder, average particle size 12 μm THV200G: tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride terpolymer, manufactured by Sumitomo 3M Co., Ltd., specific gravity 1.95, emulalon 312: coating agent, fluoropolymer powder manufactured by Acheson Co. Emuralon 345 consisting of thermosetting acrylic resin: Coating agent manufactured by Acheson Co., Ltd. SAT-500F consisting of fluororesin powder and thermosetting polyurethane: Surface treatment agent for rubber manufactured by Shinko Giken Co., Ltd., polyester and silyl isocyanate And ethyl acetate

The same adhesion test as in Examples 1 to 6 was performed on each rubber sheet that had been subjected to the baking treatment. Table 2 shows the results.

[Comparative Example 6] ST-1 (containing a crosslinking agent for fluororubber, containing an accelerator) manufactured by Dupont Dow Elastomer Co., Ltd. was diluted to a double volume with a mixed solvent of acetone / methanol (1/1).
A fluororubber treatment solution was prepared. On the other hand, a fluororubber sheet was prepared under the same blending and primary crosslinking conditions as in Examples 7 to 11. The rubber sheet before the secondary crosslinking was immersed in the fluororubber solution prepared above at room temperature for 15 minutes. The rubber sheet was taken out, air-dried for 4 hours, hot-air dried at 120 ° C. × 90 minutes, and then subjected to secondary crosslinking at 200 ° C. × 20 hours.
The same adhesion test as in Examples 1 to 6 was performed on the rubber sheet thus treated. Table 2 shows the results.

[0055]

[Table 2]

In accordance with the present invention, in the case of B) the releasable cushioning material in which the crosslinked fluorine-containing molded article (sheet) was provided with the surface layer A), all of the test pieces were peeled off without breaking at the first time and the second time. On the other hand, although the fluororubber sheet to which the surface treatment agent outside the scope of the present invention was applied showed a release property higher than that of the product of the present invention in the first adhesion test depending on the sample, the second adhesion test Of the specimens broke before peeling
(Comparative Examples 3 to 5). The ST-1 treatment of Comparative Example 6 aimed at improving the releasability by increasing the crosslink density on the surface of the fluororubber sheet, but could not obtain sufficient releasability. From these facts, it is clear that the releasable cushion material of the present invention has excellent resistance to repeated adhesion-peeling.

Example 12 400 × 300 × 0.25 m
One side of an aluminum plate of m was polished with a # 100 paper file, washed with water and dried. Metalloc S-7 (a vulcanizing adhesive for metal-fluororubber manufactured by Toyo Chemical Laboratory Co., Ltd.) was spray-applied to the polished surface and air-dried for 30 minutes.

Also, Florel FT-2230 (Sumitomo 3)
100 parts by weight of SRF-
15 parts by weight of carbon (Asahi # 50 manufactured by Asahi Carbon Co., Ltd.), 5 parts by weight of magnesium oxide, 2 parts by weight of calcium hydroxide, VC
20 parts (promoter) and 3 parts by weight of VC30 (crosslinking agent) were mixed and kneaded using a rubber kneading roll. This compounded rubber is then dissolved in 200 parts by weight of methyl ethyl ketone and applied on the metallock coating of the aluminum plate,
After drying at 70 ° C. for 20 minutes, it was kept in an oven at 230 ° C. for 5 minutes. The dry film thickness was about 100 μm.

Next, the same rubber liquid as used in Examples 1 to 6 (a liquid containing technoflon NM, PTFE powder, SRF-carbon, etc.) was applied on the rubber film and dried at 70 ° C. for 20 minutes. Thereafter, it was kept in an oven at 230 ° C. for 15 minutes.

The obtained aluminum plate / fluororubber film /
For the laminate of the surface layer, the same adhesion test as in Examples 1 to 6 was performed. For both the first and second times, all samples were not accompanied by breakage of the fluororubber film and peeling between the aluminum plate and the fluororubber film. And peeled off at the epoxy adhesive interface. The adhesive strength was good at 0.13 MPa for the first time and 0.14 MPa for the second time. The laminate was subjected to a pressurization test in which a pressure of 100 kgf / cm ² was applied at 180 ° C. for 5 minutes at 180 ° C., as in Example 6. No peeling between the film and the aluminum plate was observed. From these, it is clear that the laminate is excellent in compression resistance.

Example 13 One side of an aluminum plate having a size of 300 × 300 × 1 mm was subjected to a metallot treatment in the same manner as in Example 12. Separately, a rubber compound (Florel FT-2230 base) having the same composition as in Example 12 was prepared.

Then, the aluminum plate and the rubber compound are sandwiched in a 300 × 300 × mm size mold,
Pressed at 200 ° C. for 12 minutes. In addition, the rubber compound was arranged on the metallock-treated surface of the aluminum plate.

The obtained aluminum plate / fluororubber film /
For the laminate of the surface layer, the same adhesion test as in Examples 1 to 6 was performed. For both the first and second times, all samples were not accompanied by breakage of the fluororubber film and peeling between the aluminum plate and the fluororubber film. And peeled off at the epoxy adhesive interface. The adhesive strength was 0.12 MPa for the first time and 0.12 MPa for the second time, which was good. The laminate was subjected to a pressurization test in which a pressure of 100 kgf / cm ² was applied at 180 ° C. for 5 minutes at 180 ° C., as in Example 6. No peeling between the film and the aluminum plate was observed. From these, it is clear that the laminate is excellent in compression resistance.

[0064]

As described above, according to the present invention, there is provided a cushion material which exhibits good releasability and compression resistance and can withstand repeated use in an FPC manufacturing process and the like. The effect of the present invention is remarkable in view of the fact that conventional cushioning materials required a release film, and good release properties were not obtained only by applying a general-purpose surface treatment agent to fluororubber. is there.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 15/02 C08L 15/02 27/16 27/16 27/18 27/18 27/20 27/20 F Term (reference) 4F006 AA18 AB19 BA11 CA08 4F070 AA23 AA24 AB11 AB16 AC04 AC13 AC37 AC43 AE08 AE28 DB06 DC13 4F100 AA37H AB01B AK17A AK17B AK17C AK18A AK18C AL01A AL01C AN02A AN02C05 BA02 BA03 BA01 BA02 BA03 BA01 EJ42 EJ422 EJ86 EJ862 GB41 JK08 JK14A JK14C JL14 4J002 BB10W BD12W BD13W BD14W BD14X BD15W BD15X BD16X FD010 FD020 FD140 GH00 GQ00

Claims (6)

[Claims] 1. A) A crosslinked fluororubber surface layer which is obtained by crosslinking a fluororubber containing a fluororesin powder, and a part of the fluororesin powder is exposed on the surface; A releasable cushion material characterized by being coated with. 2. C) B ') a fluororubber sheet laminated on one or both sides of a metal plate, and B') a fluororubber sheet having a surface obtained by crosslinking A) fluororubber containing a fluororesin powder. A releasable cushion material, which is covered with a crosslinked fluororubber surface layer on which a part of the fluororesin powder is exposed. 3. The releasable cushion material according to claim 1, wherein the fluororesin powder is a polytetrafluoroethylene powder. 4. A) The crosslinked fluororubber surface layer has a specific gravity of 1.9.
0 to 1.95 of a tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride terpolymer is contained in an amount of 10 to 300 parts by weight based on 100 parts by weight of the fluororubber in the surface layer. Any one of claims 1 to 3
A releasable cushioning material according to the item. 5. A cushioning material used in bonding a substrate to a coverlay film or a reinforcing substrate in the manufacture of a flexible printed circuit board, wherein the cushioning material is used.
A cushioning material for manufacturing a flexible printed circuit, comprising the releasable cushioning material according to any one of Claims 4 to 5. 6. A liquid material containing a fluororesin powder, an uncrosslinked fluororubber, a crosslinking agent for a fluororubber and a solvent is applied to the surface of the fluororubber molded product, and after removing the solvent by drying, 10%.
A method for producing a releasable cushion material, comprising maintaining a temperature of 0 to 300 ° C. for 1 minute to 50 hours to crosslink an uncrosslinked fluororubber.