JP2569090B2 - Vulcanization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) In general, a method of blending an acrylic elastomer and a polyvinylidene fluoride resin to obtain an intended vulcanizate is performed by heating the polyvinylidene fluoride resin to a temperature equal to or higher than its melting point and flowing it. It is customary to mix the resin and the elastomer as each other, and when further vulcanizing this, usually 130
It has been determined at an arbitrary temperature in the range of vulcanization temperature from 200 ° C. to 200 ° C., for example, the maximum temperature of the vulcanizing heat medium.

(Problems to be Solved by the Invention) However, it has been found that the vulcanized product of the blend has a very large variation in tensile properties depending on vulcanization conditions. As a result of pursuing this improvement, the present invention has been achieved. is there.

(Means for Solving the Problems) That is, in the present invention, in the vulcanization of a blend of an acrylic elastomer and a polyvinylidene fluoride resin, the vulcanization is performed at a temperature equal to or higher than the melting point of the polyvinylidene fluoride resin. It provides a sulfurizing method.

The acrylic elastomer refers to a polymer mainly composed of an acrylate ester, and is usually used for the purpose of obtaining a high level of fuel oil resistance by blending with a polyvinylidene fluoride resin. To 15% by weight, 0 to 40% by weight of vinyl carboxylate, 0 to 20% by weight of acrylonitrile, and 60 to 100% by weight of alkoxyalkyl acrylate. Preferred acrylic elastomers are those obtained by polymerizing 80 to 100% by weight of alkoxyalkyl acrylate, 0 to 20% by weight of acrylonitrile, 0 to 5% by weight of ethylene and 0 to 5% by weight of fatty acid vinyl. More desirable acrylic elastomers are alkoxyalkyl acrylates 80-10
It is obtained by polymerizing 0% by weight of acrylonitrile and 0 to 20% by weight of acrylonitrile. A particularly desirable acrylic elastomer is obtained by polymerizing 85 to 95% by weight of alkoxyalkyl acrylate and 5 to 15% by weight of acrylonitrile.

The vinylidene fluoride resin used in the present invention refers to a polyvinylidene fluoride resin and a copolymer of vinylidene fluoride and another copolymerizable monomer, and other copolymerizable monomers include hexafluoropropylene, pentafluoropropylene, Fluoroethylene, trifluorochloroethylene, tetrafluoroethylene vinyl fluoride,
Perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether), other olefins, acrylates, and the like, one or more of which are used for copolymerization.

As described above, in the case of vulcanizing a blend of an acrylic elastomer in which a crosslinkable monomer is not particularly copolymerized and a polyvinylidene fluoride resin, a crosslinking agent used is a peroxide.

In the production of an acrylic elastomer, a crosslinkable monomer capable of being crosslinked by a special crosslinking agent is often copolymerized and crosslinked by the crosslinking agent. In this case, the crosslinkable monomer is added in an amount of 0.1 to 100 parts by weight of the total amount of the monomer components of the acrylic elastomer.
Using an acrylic elastomer copolymerized by 10 parts by weight, the acrylic elastomer can be crosslinked with a crosslinking agent corresponding to the crosslinking monomer.

Examples of the crosslinkable monomer include a diene compound, an epoxy group-containing ethylenic compound, a carboxyl group-containing ethylenic compound, an active halogen-containing ethylenic compound, and the like. The present invention is effective as long as the crosslinking monomer can be formed, and the type of the crosslinking monomer is not particularly limited.

When the crosslinkable monomer is a diene compound, a vulcanizing agent used for peroxides and natural rubbers is generally used, and for an epoxy group-containing ethylenic compound, other than a curing agent used for an epoxy resin. , An organic carboxylate, a dithiocarbamate, a quaternary ammonium salt, a guanidine, a sulfur compound, an alkaline earth metal hydroxide, a lead oxide, and a zinc oxide. In the case of an active halogen-containing ethylenic compound, Can be used in combination with an organic carboxylic acid ammonium salt, an organic carboxylic acid alkali metal salt and a sulfur compound.

In the case of vulcanization using a peroxide, as the peroxide, those generally used for crosslinking rubber can be used, and there is no particular limitation, for example, di-t-butyl peroxide,
t-butylcumyl peroxide, dicumyl peroxide, α, α-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) octane and the like.

A peroxide having a half-life of 1 minute or higher than the melting point of the polyvinylidene fluoride resin gives more preferable results.

Although the amount of the peroxide is not limited, it is usually used in an amount of about 1 to 10 parts by weight based on 100 parts by weight of the acrylic elastomer.

When crosslinking a blend of an acrylic elastomer and a polyvinylidene fluoride resin with a peroxide, it is more effective to use a polyfunctional monomer in combination, and the amount thereof is 15 to 100 parts by weight of the acrylic elastomer. An appropriate amount is not more than part by weight. Excess polyfunctional monomer is undesirable because it loses the flexibility of the crosslinked product. Among the polyfunctional monomers, trimethylolpropane trimethacrylate and trimethylolpropane triacrylate are the most effective. Triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, trimethylolpropane triacrylate, 1,6 hexane Diol acrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, diallyl phthalate, 1,2-polybutadiene and the like are also applicable.

In addition, the use of a radical scavenger or a thiourea derivative in peroxide crosslinking is effective in balancing the physical properties of the crosslinked product. The radical scavenger is 3 parts by weight or less based on 100 parts by weight of the acrylic elastomer. The thiourea derivative is desirably used in an amount of 5 parts by weight or less. If a large amount of the radical scavenger is used, the peroxide is consumed, deviating from the purpose of balancing the physical properties of the crosslinking agent. When a large amount of a thiourea derivative is used, the physical effect of the cross-linking agent is adversely reduced. It is desirable to use them alone or in combination within the above range.

As a radical scavenger, a compound generally used as a polymerization inhibitor or an antioxidant or sulfur or a sulfur-containing compound is used. Representative examples thereof include phenothiazine,
Examples thereof include sulfur compounds such as 6-di-t-butyl-P-cresol and a vulcanization accelerator for rubber.

In addition, various fillers, plasticizers, processing aids or stabilizers commonly used in the rubber industry can be added to suit the use of the blend.

If necessary, it is also possible to blend nitrile rubber, hydrogenated nitrile rubber, epichlorohydrin rubber, ethylene propylene rubber, butyl rubber, and boron rubber.

When the filler is used in an amount of 5 to 300 parts by weight based on 100 parts by weight of the acrylic elastomer, the state of blending and processability are improved, and more effective blending becomes possible.

As the plasticizer, those which do not impair the object of the present invention, that is, those having an affinity for the composition, for example, oligomers of α-olefins or polybutenes, polyethers,
Polyester and the like.

Further, if desired, a mixture with another rubber, for example, various rubbers having excellent fuel oil resistance, is also possible.

For the blending of the acrylic elastomer and the polyvinylidene fluoride resin and the kneading of other compounding agents, all ordinary equipment used in the rubber industry can be applied.

The vulcanization temperature needs to be higher than the melting point of the polyvinylidene fluoride resin to be blended, preferably 10 ° C. or higher than the melting point. When the polyvinylidene fluoride resin is a mixture of those having several different melting points, it is preferable that the resin has a melting point higher than the highest melting point in the mixture. When the resin having the highest melting point is very small, a temperature higher than the next higher melting point may be used, but setting a higher temperature gives a preferable result.

When the melting point of the polyvinylidene fluoride resin has a certain temperature range, it is preferable that the temperature is higher than the highest temperature.

At vulcanization temperatures below the melting point of the polyvinylidene fluoride resin, the mechanical properties of the vulcanizate of the blend are reduced.

(Action) By the vulcanization method of the present invention, a blend of an acrylic elastomer and a polyvinylidene fluoride resin has mechanical properties,
A vulcanizate exhibiting a high degree of fuel oil resistance and solvent cracking resistance can be obtained.

(Examples) (1) -1 Production of Acrylic Elastomer A In an autoclave of 130, 43 kg of water and acrylonitrile 4 were added.
kg, 36 kg of methoxyethyl acrylate, 700 g each of electrified poval B-05 and B-17 as polyvinyl alcohol, 60 g of sodium acetate, 2 g of ferric sulfate, ethylenediaminetetraacetic acid 4
g and a co-catalyst of 90 g were mixed with stirring, and the internal temperature of the autoclave was set to 45 ° C. The air above the autoclave was replaced with nitrogen.

Separately, an aqueous solution of a polymerization initiator was injected from an injection port to advance polymerization, and the injection was completed in 12 hours. An aqueous solution of Glauber's salt is added to the resulting polymer emulsion to coagulate the polymer, which is washed with water, dried and dried to obtain an acrylic elastomer A.
As a test.

(1) -2 Production of acrylic elastomer B Polyvinyl alcohol 2120 g in 130 autoclave
And 86 g of sodium acetate dissolved in an aqueous solution prepared to be 65 kg, and with stirring, vinyl acetate 8.6 kg
And 2-methoxyethyl acrylate 34.6 kg and chrysidyl methacrylate 160 g, allyl glycidyl ether 480 g
Was added and emulsified. After the inside of the autoclave was replaced with nitrogen gas, ethylene monomer was injected from above. The ethylene pressure was adjusted to 45 kg / cm ² at a polymerization temperature of 55 ° C. Separately dispens the polymerization initiator aqueous solution several times from the injection port,
After 10 hours, the polymerization was stopped, demonomerization, coagulation with a 3% aqueous solution of borax, dehydration were performed, and the dehydrated and dried polymer was used as acrylic elastomer B.

(2) Blend and Test of Acrylic Elastomer and Vinylidene Fluoride Resin Various vinylidene fluoride resins shown in Table 1 and the above-mentioned acrylic elastomer A were mixed and kneaded in the formulation shown in Table 1 as follows. A vulcanized product was prepared under vulcanization conditions, and the physical properties were measured.

(I) Kneading Using a 3 kneader, dropping a raw rubber based on 1400 g of an acrylic elastomer (raw rubber), and performing a 1-minute plain baking, then various polyvinylidene fluoride resins shown in Table 1 and all the compounding agents except peroxides Was dropped and kneaded for 3 minutes. The kneading temperatures are shown in Table 1.

The discharged blend was sheeted on a 10-inch roll at 40 ° C., allowed to cool, wound around an inch roll again at 40 ° C., kneaded with peroxide, and separated.

(3) Method of measuring physical properties of vulcanized material Physical properties After vulcanization, the specimen was left at room temperature for one day and measured by JIS K6301.

Solvent solvent growth 40 mixed solvents of isooctane 40 and toluene 60 in volume ratio
℃ 1, JIS No. 1 dumbbell punched from the vulcanized sample,
A cut similar to that of the IJK K6301 demarcia bending test was made at the center, and after setting a predetermined elongation, the sample was immersed in a mixed solvent to measure the time until cutting.

Fuel oil resistance Fuel oil resistance is Fuel C (isooctane / toluene 50/50)
Volume%) and a volume change (ΔV) after immersion in a mixture of Fuel C / ethanol 80/20 volume% at 40 ° C. for 70 hours.

(4) The results are shown in Tables 1 and 2.

(Note) The formulation examples used in Examples and Comparative Examples are as follows: 1) PENNWALT, polyvinylidene fluoride 2) PENNWALT, polyvinylidene fluoride 3) SOLVAY, polyvinylidene fluoride 4) Uniroyal 5) HAF carbon black manufactured by Tokai Carbon Co., Ltd. 6) Ester plasticizer manufactured by Adeka Argus Co., Ltd. 7) Polybutene manufactured by Nippon Petrochemical Co., Ltd. 8) Ethylene propylene rubber manufactured by Mitsui Petrochemical Co., Ltd. 9) Trimethylolpropane trimethacrylate 10) Trimethylthiourea 11) Perhexa peroxide V-40, manufactured by NOF Corporation 12) Organic sulfur compound, manufactured by Toyo Chemical Co., Ltd.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-176652 (JP, A) JP-A-58-63740 (JP, A) Plastics, 36 [2] (1985) P.I. 49−54

Claims (1)

(57) [Claims] 1. The vulcanization of a blend of an acrylic elastomer containing at least 60% by weight of an alkoxyalkyl acrylate monomer unit and a polyvinylidene fluoride resin,
A vulcanization method comprising vulcanizing at a temperature equal to or higher than the melting point of polyvinylidene fluoride resin.