JP2520433B2 - Processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) Generally, when rubber and plastic are blended, the rubber and the plastic are blended at a temperature at which the plastic is in a molten state or higher to disperse and dissolve the rubber and the plastic. It is customary.

(Problems to be solved by the invention) However, when rubber and plastic are mutually dispersed and dissolved, the processing characteristics of the blend become to reflect the characteristics of the plastic, and the rubber-like characteristics are lost. Be
For example, the processing temperature rises, and it is customary to have a drawback that an excellent molded product is difficult to be obtained in a usual molding method of rubber, and the purpose of improving the performance of the vulcanized rubber is to blend the rubber with the plastic. In this case, it is desirable that the influence of plastics reflected on the unvulcanized product is as small as possible.

In the blend of acrylic elastomer and polyvinylidene fluoride resin, the above-mentioned problems are solved, and the blend of acrylic elastomer and vinylidene fluoride resin behaves as a rubber composition in an unvulcanized state, and in a product after vulcanization The present invention has arrived at the present invention as a result of pursuing a method in which the blending effect of vinylidene fluoride resin is sufficiently exhibited.

(Means for Solving the Problems) That is, the present invention relates to a blend of an acrylic elastomer and a polyvinylidene fluoride resin, wherein the polyvinylidene fluoride resin is a powder that passes through a sieve of 50 mesh or more, and the acrylic elastomer polyvinylidene fluoride is used. This is a processing method characterized by mixing at a temperature lower than the melting point of the resin, processing and molding at a temperature lower than the melting point of the polyvinylidene fluoride resin, and then vulcanizing at a temperature not lower than the melting point of the polyvinylidene fluoride resin. According to this method, both the molding method and the physical properties after vulcanization can be satisfied.

Acrylic elastomer refers to a polymer containing an acrylic ester as a main component, and is usually blended with a polyvinylidene fluoride resin, and an acrylic elastomer used for the purpose of highly obtaining fuel oil resistance performance is ethylene. It is obtained by polymerizing 0 to 15% by weight, 0 to 40% by weight of vinylic acid carboxylate, 0 to 20% by weight of acrylonitrile, and 60 to 100% by weight of alkoxyalkyl acrylate. A preferred acrylic elastomer is 80 to 100% by weight of alkoxyalkyl acrylate and 0 to 20 of acrylonitrile.
Wt%, ethylene 0-5 wt% and fatty acid vinyl 0-5
It is obtained by polymerizing wt%. More desirable acrylic elastomer is alkoxyalkyl acrylate 80
.About.100% by weight and 0 to 20% by weight of acrylonitrile, and a particularly preferable 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 polyvinylidene fluoride and a copolymer of vinylidene fluoride and another copolymerizable monomer, and other copolymerizable monomers include hexafluoropropylene, pentafluoropropylene, and trifluoropropylene. There are ethylene, trifluorochloroethylene, tetrafluoroethylene vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro (propyri vinyl ether), other olefins, acrylic acid esters, etc., and one or more of these may be used together. Used for polymerization.

The powder of polyvinylidene fluoride resin needs to pass through a screen of 50 mesh or more, and if the powder becomes coarser than this, the performance of the blended product is deteriorated, which is not preferable. The desirable viscosity of the powder is that which passes through a screen of 250 mesh or more, more preferably that which passes through a screen of 300 mesh or more.

It is an essential condition that the blending temperature of the acrylic elastomer and the polyvinylidene fluoride resin is lower than the melting point of the polyvinylidene fluoride resin, preferably 30 ° C. or more lower than the melting point. When the polyvinylidene fluoride resin is a mixture of various polyvinylidene fluoride resins, it is necessary to mix and process the mixture at a temperature lower than the lower limit temperature of the melting point range of the mixture.

When blended at a temperature above the melting point of the polyvinylidene fluoride resin, the viscosity of the blend will increase significantly, making it difficult to process, or strain will remain during processing and molding of the blend, and dimensional stability during vulcanization will increase. Lost.

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 cross-linking monomer is added to 0.1 to 100 parts by weight of the total 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 in peroxides and natural rubber is generally used, and in the case of an epoxy group-containing ethylenic compound, a curing agent used in an epoxy resin is used. , Organic carboxylic acid ammonium, dithiocarbamate, quaternary ammonium point,
Guanidines, ionic compounds, alkaline earth metal hydroxides, lead oxides and zinc oxide can be used. In the case of active halogen-containing ethylenic compounds, organic ammonium carboxylates, organic carboxylic acid alkali metal salts and ionic compounds can be used. Can be used.

In the case of vulcanizing using a peroxide, as the peroxide, those generally used for crosslinking rubber can be used, and there is no particular limitation, but 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) butane,
2,2-bis (t-butylperoxy) octane and the like can be mentioned.

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 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 acrylic elastomer and polyvinylidene fluoride resin with peroxide, it is more effective to use a polyfunctional monomer in combination, and the amount is 15 weight per 100 weight of acrylic elastomer. An appropriate amount is a part or less. Excess polyfunctional monomer is undesirable because it loses the flexibility of the crosslinked product. The most effective polyfunctional monomers are trimethylolpropane trimethacrylate and trimethylolpropane triacrylate. Triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, trimethylolpropane triacrylate, 1,6 Hexanediol actylate, 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 radical scavenger is used, peroxide will be consumed, deviating from the purpose of balancing the physical properties of the crosslinked product. The use of a large amount of a thiourea derivative also has the adverse effect of deteriorating the physical properties of the crosslinked product.
It is desirable to use them alone or in combination within the above range.

As the radical scavenger, a compound generally used as a polymerization inhibitor or an anti-aging agent, sulfur or a sulfur-containing compound is used, and typical examples thereof include phenothiazine and 2-6.
And sulfur compounds such as di-t-butyl-P-cresol and vulcanization accelerators 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, nitrile rubber, hydrogenated nitrile rubber, epichlorohydrin rubber, ethylene propylene rubber, butyl rubber, fluororubber, etc. can be blended.

The amount of the filler used is 5 to 300 parts by weight with respect to 100 parts by weight of the acrylic elastomer, the blending state and the processability are improved, and more effective blending becomes possible.
Examples of the plasticizer include those which do not impair the object of the present invention, that is, those which have an affinity for the composition, for example, α-olefin oligomers or polybutenes, polyethers and polyesters.

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 scarce, the temperature may be higher than the next highest melting point, but it is preferable to set the temperature higher.

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

(Operation) According to the processing method of the present invention, the blended product can be processed very easily in the state of unvulcanized rubber, and a molded product of unvulcanized rubber with a smooth compound surface and a small internal strain can be obtained. Excellent front and rear dimensional stability. By the vulcanization method of the present invention, a vulcanizate exhibiting the blending effect of polyvinylidene fluoride resin, fuel oil resistance, and solvent crack growth 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, methoxyethyl acrylate 36 kg, polyvinyl alcohol as electrified Poval B-05 and B-17 700 g each, sodium acetate 60 g, ferric sulfate 2 g, ethylenediamine tetraacetic 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 in the upper part of the autoclave was replaced with nitrogen.

The polymerization initiator aqueous solution was separately injected from the injection port to allow the polymerization to proceed, 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.
I tried it as.

(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, clidydyl methacrylate 160 g, allyl glycidyl ether 480 g
Was added to emulsify, after replacing the inside of the autoclave with nitrogen gas,
Ethylene monomer was pressed in from the top. The ethylene pressure was adjusted to 45 kg / cm ² at a polymerization temperature of 55 ° C. Separately, the aqueous solution of the polymerization initiator was added several times through the injection port, the polymerization was stopped in about 10 hours, and the polymer was demonomerized, coagulated with a 3% borax aqueous solution, dehydrated, and dehydrated and dried to obtain an acrylic elastomer B. I tried it as.

(2) Polyvinylidene fluoride resin As shown in Table 1, polyvinylidene fluoride KYNAR2800 manufactured by Henwalt Co., Ltd. was frozen and crushed, and then a sample obtained by screening and powdered KYNAR2801 and KYNAR741 of KYNAR2800 were used.

(3) Blend Using a 3 kneader, 1400 g of an acrylic elastomer (raw rubber) was dropped as a base, and after kneading for 1 minute, the polyvinylidene fluoride resin shown in Table 2 and all compounding agents except the vulcanizing agent were dropped. Then, the mixture was kneaded for 3 minutes, placed for 3 minutes, and then discharged. The kneading temperature is shown in Table 2.

The discharged blended product was sheeted at 40 ° C. with a 10-inch roll, allowed to cool, and then wound again at 90 ° C. on a 10-inch roll, and the vulcanizing agent was kneaded and discharged.

(4) Extrusion L / D = 400mm / 50mm extruder is used, cylinder temperature: input port / intermediate part / die attachment port / die head 50/70/90
A hose with an inner diameter of 9 mm and an outer diameter of 13 mm was extruded at a screw rotation of 20 rpm at / 110 ° C.

(5) Vulcanization Vulcanization was performed under the vulcanization conditions shown in Tables 2 and 3.

(6) Shrinkage measurement of extruded product The yield (%) in the length direction of the hose after vulcanization by a steam vulcanizer was measured under the press vulcanization conditions shown in Tables 2 and 3.

(7) Physical properties After vulcanization, it was left at room temperature for 1 day and various physical properties were measured by JIS K6301. Table 2 shows the results.

 However, solvent growth growth was measured by the following method.

(I) Solvent crack growth: 40 parts of a mixed solvent of isooctane 40 and toluene 60 in a volume ratio are used.
JIS No. 1 dumbbell was punched out from the sample whose shrinkage of the extruded product was measured by keeping it at ℃ Was measured.

(Ii) Fuel oil resistance: Fuel C (isooctane / toluene 50 /
50% by volume) and Fuel C / 80/20% by volume of ethanol were immersed in a mixed solution at 40 ° C. for 70 hours, and the volume change (ΔV) was determined.

Continuation of the front page (56) Reference JP 61-176652 (JP, A) JP 58-63740 (JP, A) JP 64-54050 (JP, A) JP 58-56384 (JP) , B2)

Claims (1)

(57) [Claims] 1. A blend obtained by mixing an acrylic elastomer and a polyvinylidene fluoride resin that passes through a screen of 50 mesh or more at a temperature lower than the melting point of the polyvinylidene fluoride resin and at a temperature lower than the melting point of the polyvinylidene fluoride resin. Of a blend of acrylic elastomer and polyvinylidene fluoride resin, characterized by vulcanizing at a temperature above the melting point of polyvinylidene fluoride resin