JP4229004B2 - Fluoro rubber composition - Google Patents

Description

  The present invention relates to a fluororubber composition. More specifically, the present invention relates to a fluororubber composition suitably used as a molding material for a cushion material for molding press used in hot press molding.

  In the case of forming a sheet-like material by hot pressing, a method in which a molding material is sandwiched between a hot platen and a constant pressure and heat is applied is generally used. In such press molding, a metal mirror plate is usually placed on the surface that is in direct contact with the workpiece, while a uniform pressure and heat is applied to the entire surface of the workpiece, so that a gap between the hot platen and the mirror plate is used. It is performed with a flat cushioning material interposed. For this reason, such cushion materials are required to have functional characteristics such as cushioning properties, thermal conductivity, heat resistance, durability, and moldability.

  For such purpose of use, as a cushioning material for molding presses, a stack of about 5 to 20 kraft papers was used, but this cushioning material has excellent cushioning properties especially in the initial use. Although it has, it is remarkably inferior in durability in repeated use, and the use up to about 1 to 5 times is an allowable limit, and in recent years it has hardly been used.

  On the other hand, as a cushion material with improved durability, a material using a synthetic rubber laminated material, specifically, a layer of a cloth or non-woven fabric made of heat-resistant fibers such as glass fiber and aromatic polyamide fiber, and butyl rubber, etc. A synthetic rubber layer combined with a synthetic rubber layer has been proposed and is still widely used. Further, for the purpose of imparting releasability to these, a heat-resistant release layer such as a fluororesin film is bonded and integrated on the surface of the cushion material.

  However, the cushion material using the synthetic rubber laminated material has a problem that the heat resistance is not so good while it is excellent in cushioning properties and durability in repeated use as compared with kraft paper. In particular, molding of printed circuit boards and electrical insulating plates, for which demand has been increasing in recent years, tends to increase in temperature. For example, press molding may be performed at high temperatures such as 230 to 250 ° C, improving the heat resistance of cushion materials. It is hoped to do.

In order to improve such a problem, it has been attempted to use, for example, silicone rubber or fluorine rubber, which is a heat-resistant rubber, as a cushioning material. However, since silicone rubber is an organic peroxide vulcanization system, there is a problem that unreacted vulcanizing agent deteriorates the product, or low molecular silicone oil oozes out and contaminates the pressed product. On the other hand, in order to prevent the fluororubber from adhering to the molded article due to its adhesiveness, for example, as proposed in Patent Document 1 below, tetrafluoroethylene-hexafluoropropene copolymer is formed on the entire surface of the fluororubber layer. There has been proposed a sheet for hot pressing in which release properties and durability are improved by coating with a surface layer made of resin. However, the cushioning material having such a multilayer structure has a problem to be solved such that the manufacturing process is complicated and the cost is increased.
Japanese Utility Model Publication No. 4-28755

On the other hand, in order to reduce the cost of fluororubber, attempts have been made to improve it by blending a large amount of a filler having a particularly large particle diameter in fluororubber. It is necessary to form a multilayer structure composed of mold layers, which leads to complicated processes and increased costs. Further, since the hardness of the fluororubber is high, there is a disadvantage that the adhesive or the like of the printed circuit board flows out.
Japanese Examined Patent Publication No. 7-12617

  An object of the present invention is to provide a fluororubber composition used for a cushion material for molding presses having excellent cushioning properties, thermal conductivity, heat resistance, durability, molding processing (non-adhesiveness) and the like.

  The object of the present invention is (a) per 100 parts by weight of a peroxide-crosslinkable fluorine-containing elastomer obtained by copolymerizing a fluorine-containing olefin in the presence of a bromine and / or iodine-containing crosslinking point forming compound ( b) a molding press comprising 0 to 5 parts by weight of carbon black, (c) 0.1 to 1.5 parts by weight of an organic peroxide crosslinking agent and (d) 0.1 to 1.5 parts by weight of a polyfunctional unsaturated compound co-crosslinking agent. This is achieved by a fluororubber composition used as a cushioning material.

  The vulcanized molded product obtained from the fluororubber composition according to the present invention has a well-balanced cushioning property, thermal conductivity, heat resistance, durability, molding processing (non-adhesive) property, etc. required for a molding press cushioning material. Since the excellent effect of satisfying is exhibited, the rubber layer alone can be effectively used as a cushioning material for molding press.

(a) Peroxide-crosslinkable fluorine-containing elastomer is at least a fluorine-containing olefin such as vinylidene fluoride [VDF], hexafluoropropene [HFP], tetrafluoroethylene [TFE], perfluorovinyl ether, chlorotrifluoroethylene, etc. One kind is obtained by polymerizing in the presence of bromine-containing and / or iodine compound, and ethylene, propylene and the like can be further copolymerized there. Here, examples of the perfluorovinyl ether include the following compounds.
CF ₂ = CFOCF ₃
CF ₂ = CFOC ₂ F ₅
CF ₂ = CFOC ₃ F ₇
CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] _{1 to 4} CF ₃
CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] _1-4 C ₃ F ₇
CF ₂ = CFO (CF ₂ ) _n OCF ₃
CF ₂ = CFOCF ₂ CF ₂ O (CF ₂ O) _n CF ₃

  More specifically, copolymers of vinylidene fluoride and other fluorine-containing monomers, such as vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer, vinylidene fluoride-hexafluproppropene copolymer Examples thereof include a polymer and a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer.

Further, examples of the bromine-containing and / or iodine compound used for forming a crosslinking point in the fluorine-containing elastomer include the following saturated or unsaturated compounds.
CF ₂ = CFBr
CF ₂ = CFI
CF ₂ = CHBr
CF ₂ = CHI
CH ₂ = CHCF ₂ CF ₂ Br
CH ₂ = CHCF ₂ CF ₂ I
CF ₂ = CFOCF ₂ CF ₂ Br
CF ₂ = CFOCF ₂ CF ₂ I
CH ₂ = CHBr
CH ₂ = CHI
Br (CF ₂ ) ₄ Br
I (CF ₂ ) ₄ I
Br (CH ₂ ) ₂ (CF ₂ ) ₄ CH ₂ CH ₂ Br
I (CH ₂ ) ₂ (CF ₂ ) ₄ CH ₂ CH ₂ I
ICF ₂ CF ₂ Br

  (b) Carbon black is a grade such as thermal carbon having a large particle size and soft elasticity, preferably MT grade, about 0 to 5 parts by weight, preferably about 0 to about 100 parts by weight of fluorine-containing elastomer. Used in a ratio of 2 parts by weight. If carbon black is used in a proportion higher than this, the hardness of the resulting vulcanized product will be as high as 55 or more, and the printed circuit board will flow out, which is not preferable. When carbon black is not used, the rubber hue becomes uneven and the product hue is not stable.

  The fluorine-containing elastomer copolymerized with a bromine and / or iodine-containing crosslinking point forming compound is crosslinked with an organic peroxide. Examples of the organic peroxide (c) used as a crosslinking agent include tertiary butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, Diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di (tert-butyl) Peroxy) cyclododecane, 2,2-di (tert-butylperoxy) octane, 1,1-ditert-butylperoxycyclohexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) Hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (Benzoylperoxy) Xanthone, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (tert-butylperoxy) valerate, benzoyl peroxide, m-toluylper Oxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tertiary butyl peroxyisobutyrate, tertiary butyl peroxy-2-ethylhexanoate, tertiary butyl peroxybenzoate, tertiary butyl Peroxyisopropyl carbonate, tertiary butyl peroxyallyl carbonate, and the like are used at a ratio of about 0.1 to 2 parts by weight, preferably about 0.5 to 1.5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer.

  When performing peroxide crosslinking, a polyfunctional unsaturated compound is used in combination as a co-crosslinking agent. When this co-crosslinking agent is used together with an organic peroxide, a vulcanized property is improved, and a fluorinated rubber vulcanizate having excellent mechanical strength and compression set resistance can be obtained. Examples of (d) polyfunctional unsaturated compounds include tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate, triallyl trimellitate, trimethylolpropane trimethacrylate, N, Nm-phenylenebismaleimide, diallyl At least one of phthalate, tris (diallylamine) -s-triazine, 1,2-polybutadiene, ethylene glycol di (meth) acrylate, diethylene glycol diacrylate and the like is about 2 parts by weight or less, preferably about 2 parts by weight per 100 parts by weight of the fluorine-containing elastomer. Used in a proportion of 0.5 to 1.5 parts by weight.

  In the composition comprising the above components, other compounding agents such as reinforcing agents other than carbon black, fillers, acid acceptors, anti-aging agents, lubricants, plasticizers, pigments and the like are added as necessary. After kneading with a roll, a closed kneader or the like, vulcanization molding is performed by a compression molding method, an injection molding method or the like according to generally used crosslinking conditions. The cushion material is generally formed into a sheet having a thickness of about 0.1 to 10 mm, preferably about 1 to 3 mm.

  Next, the present invention will be described with reference to examples.

Example 1
In an aqueous medium, the iodine-containing bromine compound IBrTFE (ICF ₂ CF ₂ Br) is used as a chain transfer agent, ammonium persulfate is used as a polymerization initiator, and a copolymerization reaction of VDF and HFP is carried out to produce copolymer A (VDF / HFP molar ratio = 78/22) was obtained. next,
100 parts by weight of copolymer A
MT carbon black 1 〃
Triallyl isocyanurate 1 〃
2,5-dimethyl-2,5-di (tert-butylperoxy) hexane 1〃
Basic magnesium, aluminum, hydroxy 3 〃
Carbonate hydrate (Kyowa Chemical Product DHT-4A)
The above blend was kneaded with an 8-inch mixing roll, and the kneaded product was compression molded at 180 ° C. for 10 minutes to produce a fluororubber cushion material (thickness: 1.5 mm).

Comparative Example 1
In an aqueous medium, ammonium persulfate was used as a polymerization initiator to carry out a copolymerization reaction of VDF and HFP to obtain a copolymer B (VDF / HFP molar ratio = 78/22). next,
100 parts by weight of copolymer B
MT carbon black 1 〃
Calcium hydroxide 6 〃
Magnesium hydroxide 3 〃
Bisphenol AF 2 〃
Benzyltriphenyl phosphate 0.4 〃
The above blend was kneaded with an 8-inch mixing roll, and the kneaded product was compression molded at 180 ° C. for 10 minutes to produce a fluororubber cushion material (thickness: 1.5 mm).

Example 2
In Example 1, instead of the copolymer A, an iodine-containing compound DIFOB (I (CF ₂ ) ₄ I) is used as a chain transfer agent and IDFE (CF ₂ = CHI) is used as a crosslinking point monomer in an aqueous medium. And copolymer C (VDF / HFP / TFE molar ratio = 66/18/16) obtained by copolymerizing VDF, HFP and TFE using ammonium persulfate as a polymerization initiator. It was.

Comparative Example 2
In Comparative Example 1, copolymer D obtained by conducting a copolymerization reaction of VDF, HFP and TFE using ammonium persulfate as a polymerization initiator in an aqueous medium instead of copolymer B. (VDF / HFP / TFE molar ratio = 60/19/21) was used.

Comparative Example 3
In Example 2, the MT carbon black amount was changed to 15 parts by weight.

Comparative Example 4
In Comparative Example 1, 10 parts by weight of fluorine oil (Unimatec product Aflunox # 400) was further used.

As described above, the normal value, the adhesive strength, the adhesive flow-out property, and the fatigue evaluation were performed on the fluororubber cushion materials obtained in the respective Examples and Comparative Examples.
Normal value: Compliant with JIS K6253, JIS K6251 Adhesive strength: When a polyimide film of 0.2 mm x 130 mm x 130 mm is crimped to a rubber cushion at 160 ° C / 100 seconds at a pressure of 2 Pa, and one end is pulled with a clip immediately after release Adhesive flow-out property: When using a rubber cushioning material to press-bond polyimide film and copper foil at a pressure of 1 MPa, the adhesive flowed out by 0.1 mm or more, and less (Note that if the adhesive flows out from a part of the printed circuit board, the adhesive is transferred to the rubber mat, and this transferred product may remain as a foreign substance in the next product, which is not preferable.)
Fatigue evaluation: 160 ° C / 100 seconds crimping is repeated 50 times to determine whether the rubber cushion material is broken

The results obtained are shown in the following table.
table
Real 1 ratio 1 Real 2 ratio 2 Ratio 3 ratio 4
Hardness (Duro A) 50 53 48 53 61 45
Breaking strength (MPa) 9.5 7.0 10.3 6.2 13.5 4.5
Adhesive strength (g / cm) 1.5 13.5 1.3 13.0 3.5 15.9
Adhesive flow-out property No Yes No Yes Yes-
Fatigue assessment No No No No No Yes

The fluororubber composition according to the present invention is, for example, a cushioning material for hot press molding when producing decorative plywood, printed circuit boards, electrical insulating boards, rigid polyvinyl chloride laminates, etc. made of melamine resin, phenol resin, epoxy resin, etc. It is suitably used as a molding material.

Claims (7)

  (b) per 100 parts by weight of a peroxide-crosslinkable fluorine-containing elastomer obtained by copolymerizing a fluorine-containing olefin in the presence of a bromine and / or iodine-containing crosslinking point forming compound, and (b) carbon black 0-5 Fluorine used as a cushioning material for molding presses, containing 0.5 parts by weight, (c) 0.5 to 1.5 parts by weight of an organic peroxide crosslinking agent and (d) 0.5 to 1.5 parts by weight of a polyfunctional unsaturated compound co-crosslinking agent Rubber composition.   The fluororubber composition according to claim 1, which gives a cushioning material for molding press having a rubber hardness (Duro-A) of 45 to 55 during vulcanization molding.   (a) Component The fluororubber composition according to claim 1, wherein the fluorine-containing elastomer is a bromine and / or iodine-containing vinylidene fluoride-hexafluoropropene copolymer.   (a) Component The fluororubber composition according to claim 1, wherein the fluorine-containing elastomer is a bromine and / or iodine-containing vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer.   A cushion material for molding press, which is vulcanized and molded from the fluororubber composition according to claim 1, 2, 3 or 4.   The cushioning material for molding presses according to claim 5, which is used by being interposed between a metal mirror plate and a hot plate that are in direct contact with the object to be molded. The cushion material for molding presses according to claim 5 or 6, which is used for hot press molding of a printed circuit board or an electrical insulating plate.