JP2537906B2 - Fluorine rubber composition for vulcanization adhesion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composition for vulcanizing adhesives, and more particularly to a fluororubber composition for vulcanizing adhesion with improved adhesion to metal.

[Conventional technology and problems]

Vinylidene fluoride (VdF) / hexafluoropropylene (HF
P) type and vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene (TFE) type. This polyol vulcanized fluororubber is particularly excellent in compression set at high temperature and is used as various rubber products. Among them, it is often used as a composite material such as an oil seal in which rubber and metal are adhered.
However, fluorine rubber is inferior to other general-purpose rubbers in terms of adhesiveness to metal, and adhesion to metal is not performed well, resulting in a high defective rate of products.

Hitherto, a method has been proposed (Dyupon Cataloc VT450.1) in which a large amount (about 15 parts by weight) of low-activity magnesium oxide is blended using a primer. However, with a fluorine rubber having a higher molecular weight than that of a conventional commercially available fluorine rubber, sufficient adhesiveness cannot be obtained by compounding low-activity magnesium oxide.

[Means for solving problems]

The object of the present invention is to provide a fluorine rubber composition for vulcanization adhesion which has improved vulcanization adhesion between a high molecular weight fluorine rubber and a metal, which are superior in heat resistance, compression set oil resistance, etc. to conventional commercially available fluorine rubber. To provide things.

The present invention has a fluorine content of 63.5 to 71% by weight and an intrinsic viscosity [η] (measuring solvent methyl ethyl ketone, measuring temperature of 35 ° C.) of 100 to 250.
(Ml / g), content of fraction with molecular weight of 50,000 or less (M ₅ )
Is less than 5% by weight, and the content of the fraction having a molecular weight of 1,000,000 or more (M ₁₀₀ ) is 10 to 35% by weight, 100 parts by weight of fluorine rubber, 0.1 to 10 parts by weight of polyol vulcanizing material, and 0.05% of polyol vulcanization accelerator. ~ 2 parts by weight, 1 to 30 parts by weight of metal hydroxide, 5 to 25 parts by weight of highly active magnesium oxide (preferably 10 to 15 parts by weight) where the activity value of magnesium oxide is 100 (mg / g) or more A composition for vulcanization and adhesion comprising: The fluororubber used in the present invention has a fluorine content of 63.5 to 71% by weight, an intrinsic viscosity number (ml / g) of 100 to 250, and a content of claxion having a molecular weight of 50,000 or less (a ratio of a polymer having a molecular weight of 50,000 or less). (M ₅ )
Is 5% by weight or less and the content (M ₁₀₀ ) of the fraction having a molecular weight of 1,000,000 or more is 10 to 35% by weight.

The fluororubber used in the present invention preferably contains vinyldenfluoride (VdF) units and hexafluoropropylene (HFP) units, the sum of which is 65 to 100% by weight, and tetrafluoroethylene (TFE) units are included. It is contained in an amount of 35 to 0% by weight, and the weight ratio of vinylidene fluoride units to hexafluoropropylene units is in the range of 80:20 to 40:60.

Details of the fluorine rubber suitable for the present invention and the method for producing the same are described in, for example, Japanese Patent Application No. 62-112139. A polymerization method suitable for producing the fluororubber of the present invention is a suspension polymerization method.
The reaction conditions for producing the fluororubber of the present invention by suspension polymerization include, for example, a polymerization temperature of 50 ° C. or higher, and the catalyst is a hydrocarbon-based peroxydicarbonate such as diisopropyl peroxydicarbonate. As a method of adding the above, batch charging is carried out, and the polymerization time is 7 to 18 hours. The polymerization time can be shortened by increasing the polymerization pressure. If the intrinsic viscosity number (ml / g) of fluorine rubber is less than 100, the dispersibility of MgO and other compounds during kneading may be poor, and the vulcanization state during bonding may be poor, resulting in poor adhesion. Many. In addition, the intrinsic viscosity of fluorocarbon rubber (ml / g) is 250
If it exceeds the range, the rigidity of the polymer increases, and the adhesion with the metal decreases during adhesion (the anchor effect and the like are poor), resulting in an increase in poor adhesion. Therefore, the intrinsic viscosity number (ml / g) is 100-250 as fluorocarbon rubber that can obtain good vulcanization adhesion.
It is preferably 120 to 220, M ₅ is 5% by weight or less, M
_{When the} content of ₁₀₀ is 10 to 35% by weight, preferably 15 to 30% by weight, the problems of the dispersibility of the compound and the anchoring effect are eliminated, and the adhesiveness can be improved.

The highly active magnesium oxide used in the present invention has an activity value of 1 g of magnesium oxide (hereinafter referred to as MgO)
g number] is 100 or more, it is a highly active magnesium oxide, has a very large specific surface area, and is very physically and chemically active. Specifically, Kiyowamag 150
(Kyowa Chemical Industry Co., Ltd.) The reason why the adhesion is improved by using high activity magnesium oxide is that it is ultrafine particles of MgO, so the dispersibility is improved and the acid gas is smoothly received (neutralized) during vulcanization. It is considered that this is because the adhesive and the adhesion between the adhesive and the rubber are not adversely affected.

By setting the blending amount to be in the range of 5 to 25 parts by weight, preferably 10 to 15 parts by weight, based on 100 parts by weight of fluororubber, the vulcanization adhesive with metal can be significantly improved. If the amount is less than the above amount, the vulcanization adhesion is extremely poor and the defective rate of the product is high. On the other hand, if the amount is larger than the above amount, the hardness becomes high and the flow at the time of press vulcanization becomes worse.
In terms of physical properties, elongation is lost and compression set becomes extremely poor. From the above, as a proper compounding amount, the range of 5 to 25 parts by weight, preferably 10 to 15 parts by weight, relative to 100 parts by weight of fluororubber is most balanced in vulcanization adhesiveness and vulcanized physical properties. As a compounding recipe, highly active magnesium oxide 5 to
A system in which 25 parts by weight of low activity magnesium oxide is further mixed may be used.

The vulcanizing agent used in the composition of the present invention is a fluorine-containing polyhydroxy compound, and is 2,2-bis (4-hydroxyphenyl) perfluoropropane [bisphenol AF], 2,2
-Bis (4-hydroxyphenyl) perfluoropropane, 2- (4'-hydroxyphenyl) 1,1,1,3,3,3-
Hexafluoro-2-propanol, HOCH ₂ (CF ₂ ) ₃ CH ₂ O
H, HOCH ₂ CF ₂ CFH (CF ₂ ) ₃ CFHCF ₂ CH ₂ OH, HOCH ₂ CH ₂ CH ₂ (CF ₂ ) ₃ CH ₂ CH ₂ CH ₂ OH, etc. are exemplified, and among these, bisphenol AF is preferable. Fluorocarbon rubber used 10
It is used in an amount of 0.1 to 10 parts by weight, preferably 0.6 to 5 parts by weight, per 0 parts by weight.

As the vulcanization accelerator, a quaternary onium salt compound, a quaternary phosphonium salt, a quaternary ammonium salt or an iminium salt, for example, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium muchloride, tetrabutylammonium chloride,
Tetrabutylammonium bromide, bis (benzyldiphenylphosphine) iminium chloride, tetrabutylphosphonium chloride, benzintriphenylphosphonium chloride, benzyltrioctylphosphonium chloride, etc. are suitable, and 0.0 per 100 parts by weight of fluorine rubber.
It is used in an amount of 5 to 2 parts by weight, preferably 0.1 to 1 part by weight.

The metal hydroxide is used as an acid binder, magnesium, calcium, zinc, lead and other hydroxides are exemplified,
Among them, calcium hydroxide is preferable. The amount used is 1 to 30 parts by weight, preferably 2 per 100 parts by weight of fluororubber.
Used in a proportion of up to 20 parts by weight.

Fillers and reinforcing agents can be used in the present invention. For example, carbon black, silica, clay, talc, etc. are used as necessary.

〔Example〕

Next, the present invention will be specifically described with reference to examples. In the examples, various analysis methods and methods for measuring physical properties were according to the following methods.

1) Analytical method The conditions for measuring the intrinsic viscosity and molecular weight distribution (M ₅ ) of fluorine rubber are as follows.

(1) Intrinsic viscosity [η] A 0.1 g / 100 ml concentration solution using methyl ethyl ketone as a solvent is measured at 35 ° C. using a capillary viscometer.

(2) Molecular weight distribution Liquid chromatograph: LC-3A type (manufactured by Shimadzu Corporation) Column: KF-80M (two) + KF-8
00P (Pre-column) (Showa Denko KK) Detector: ERC-7510S (Elma Optical Co., Ltd.) Integrator: 7000A (System Instruments) Development solvent: Tetrahydrofuran Humidity: 0.1 wt% Temperature: 35 ° C Molecular weight calibration line standard polymer: monodisperse polystyrene various (manufactured by Toyo Soda _{(Ltd.)) (M W / M n} = 1.2 (max)) M 5, M 100 is calculated from the results.

2) Adhesion test method 1. Metal test piece Co., Ltd. test piece-Thickness 1mm x 50mm x 15mm-Stainless steel JIS G4305 (SUS304) -Mild steel JIS G3141 (SPCC B) 2. Surface treatment-Stellence steel No polishing- Mild steel Side paper ^# 240 Polishing / degreasing cleaning Methyl ethyl ketone 3. Adhesive Monikas CF5M Yokohama Polymer Research Institute (manufactured) 4. Coat / apply once 5. Vulcanization adhesion condition After application of adhesive, dry at room temperature . After about 30 minutes, the adhesive-coated metal is placed in a mold with the surface of the metal facing upward, and the vulcanization-adhesive composition is placed thereon and vulcanized and adhered.

Breath vulcanization 180 ° C 10 minutes Oven vulcanization 232 ° C 24 hours 6. Peeling test method and evaluation (1) Peeling test method The rubber part of the above rubber-bonded test piece was rubbed with pechin.
° Peel off. In the case of rubber breakage due to stress concentration, it is peeled off from other parts in the same manner, and in the case of rubber breakage, the same method is repeated to determine.

(2) Evaluation The adhesion was evaluated as follows.

The above evaluation was performed, and the% display of M-RC-R was also shown.

M: Peeling between metal and adhesive RC: Peeling between rubber part and adhesive R: Peeling of rubber part The comprehensive evaluation (n = 4 test pieces) is shown as follows.

◎ Excellent ○ Good △ Yes × No Example 1 An autoclave with an internal volume of about 15 l equipped with an electromagnetic induction stirrer was thoroughly scavenged with nitrogen gas, and after decompression-N ₂ filling was repeated 3 times to replace nitrogen. , Deoxidized pure 5800 g, 1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter referred to as CFC 113) 2670 g, and methyl cellulose (viscosity 50 cp) 2.9 g as a suspension stabilizer under reduced pressure The temperature was maintained at 50 ° C while charging and stirring at 500 rpm. Then, a mixed monomer consisting of 26.4% by weight of VdF, 68.1% by weight of HFP, and 5.5% by weight of TFE was charged as a charging gas to 13 Kg / m ² -G. Next, as a catalyst, Freon 113 containing 10.5% by weight of diisopropyl peroxydicarbonate was used.
51 g of the solution was charged and the polymerization was started. 1 pressure due to polymerization
Since drops to 2.5Kg / m ² -G VdF55.3 wt%, HFP28.3
A mixed monomer consisting of 1% by weight of TFE and 16.4% by weight of TFE was added as an additional gas, and the pressure was returned to 13 kg / cm ² -G again. Such an operation was repeated to carry out a polymerization reaction for 9 hours. After the completion of the polymerization reaction, the remaining mixed monomer was scavenged, the resulting suspension was dehydrated with a centrifuge, washed thoroughly with water, and then washed with 10
It was vacuum dried at 0 ° C. to obtain about 8 kg of rubber. When the obtained fluorine rubber was analyzed by ¹⁹ FNMR, it was found that the VdF unit was 55.1% by weight, the HFP unit was 29.1% by weight, and the TFE unit was 15.8% by weight.
The [η] was 228.

The fluorocarbon rubber was extruded by heating and kneading under the following extruder and extrusion conditions, and then allowed to cool after cutting with a hot cutter,
It was made into a pellet shape.

(Extruder)

Nippon Steel Co., Ltd. Model: TEX44PS-30AW-2V (biaxial) [Extrusion conditions] Heating temperature 170 ℃ Screen rotation speed 300rpm Sample feeding rate 30Kg / hr [η] of the obtained pelletized fluororubber is 169, _n
Is 23.9 × 10 ⁴ , _w / _n is 2.2, M ₅ is 2.0% by weight, M ₁₀₀
Is 13.3% by weight, and the Mooney viscosity [ML _{1 + 10} (121
° C)] was 102.

Example 2 The composition of the charged monomer was VdF 5.4% by weight and HGP 90.6% by weight. T
FE4.0% by weight, added monomer composition is VdF39.4% by weight, HFP3
The procedure of Example 1 was repeated except that the polymerization time of 8.8% by weight and TFE21.8% by weight was 11 hours. [Η] of the obtained fluororubber was 143, _n was 16.1 × 10 ⁴ , _w / _n was 2.7, M ₅
Is 4.9%, M ₁₀₀ is 10.2%, and Mooney viscosity [ML _{1 + 10}
(121 ° C.)] was 143.

Example 3 Pure freon 113 and a suspension stabilizer were charged in the same manner as in Example 1, and the temperature was kept at 50 ° C. while stirring at 500 rpm. Then, a mixed monomer consisting of 16.9% by weight of VdF and 83.1% by weight of HFP was charged as a charging monomer to 15.0 Kg / m ² -G, and then CFC containing 10.5% by weight of diisopropyl peroxydicarbonate as a catalyst. 51 g of solution
Was charged to start the polymerization. At this time, the pressure is increased by the polymerization.
Since drops to 14.5Kg / m ² -G VdF51.7 wt%, HFP48.
A mixed gas consisting of 3% by weight was added as an additional monomer, and the pressure was adjusted to 15 kg / m ² -G again. This operation was repeated during the polymerization reaction for 15 hours for polymerization to obtain about 5 kg of fluororubber. The composition of this fluororubber was VdF unit 52.0% by weight, HFP unit 48.0% by weight, [η] was 151, and _n was 17.9 × 10 ⁴ ,
_w / _n was 3.2, M ₅ was 4.3%, M ₁₀₀ was 19.6%, and Mooney viscosity [ML _{1 + 10} (121 ° C.)] was 133.

Examples 4 to 9 and Comparative Examples 1 to 5 The fluorocarbon rubbers obtained in Example 1 and Technoflon FOR-45Bi (a binary copolymer fluorocarbon rubber manufactured by Montedison Co. [η] = 80 (mg / g) as comparative examples. ) M ₅ = 20 (%) M ₁₀₀ = 16
(%)) Was also used, and the compounding prescriptions shown in Tables 1 and 2 were used to knead with a roll to evaluate the vulcanization adhesion of rubber and metal. The results are shown in Tables 3 and 4.

[Effects of the Invention] As described above, the vulcanization adhesiveness between the high molecular weight fluorine rubber and the metal was remarkably improved by incorporating the highly active magnesium oxide.

Claims (1)

(57) [Claims] 1. A fluorine content of 63.5 to 71% by weight, an intrinsic viscosity [η] (measuring solvent methyl ethyl ketone, measuring temperature 35 ° C.)
Of 100 to 250 (ml / g), the content of the fraction having a molecular weight of 50,000 or less (M ₅ ) is 5% by weight or less, and the content of the fraction having a molecular weight of 1 million or more (M ₁₀₀ ) is 10 to 35% by weight. Base rubber 100 parts by weight, polyol vulcanizing agent 0.1 to 10 parts by weight, polyol vulcanization accelerator 0.05 to 2 parts by weight, metal hydroxide 1 to 30 parts by weight, magnesium oxide activity value of 100 (mg / g) or more A vulcanizing and bonding composition comprising 5 to 25 parts by weight of highly active magnesium oxide.