JPH01152133A - Processing method - Google Patents

Abstract

PURPOSE:To obtain a vulcanizate excellent in dimensional stability, fuel oil resistance and resistance to propagation of solvent cracking in good moldability, by mixing an acrylic elastomer with a polyvinylidene fluoride resin powder at a specified temperature and molding the mixture. CONSTITUTION:An acrylic elastomer (A) obtained by polymerizing, for example, 90-100wt.% alkoxyalkyl acrylate with 0-20wt.% acrylonitrile, 0-5wt.% ethylene and 0-5wt.% fatty acid vinyl ester is mixed with a polyvinylidene fluoride resin powder obtained by passing, e.g., a vinylidene fluoride homopolymer or a copolymer of vinylidene fluoride with other copolymerizable monomers (e.g., hexafluoropropylene) through a 50-mesh or finer screen at a temperature lower than the melting point of component A to obtain a blend. This blend is optionally mixed with a crosslinking agent (e.g., peroxide), a radical scavenger, a thiourea derivative, etc. (C) and a filler, a plasticizer, a processing aid, a stabilizer, etc. (D), and the resulting mixture is molded at a temperature lower than the melting point of component A.

Description

[Detailed Description of the Invention] (Prior Art) Generally, when blending rubber and plastic, the blending with rubber is carried out at a temperature higher than the temperature at which the plastic melts, thereby dispersing and dissolving the rubber and plastic. This is the norm.

(Problem to be solved by the invention) However, when rubber and plastic are mutually dispersed and dissolved, the processing characteristics of the blend come to reflect the properties of the plastic, and the rubbery properties are lost. As a result, for example, the processing temperature increases, and it is common for conventional rubber molding methods to have drawbacks such as difficulty in obtaining excellent molded products.

In the case of a blend of acrylic elastomer and polyvinylidene fluoride resin, if the polyvinylidene fluoride resin is blended in a molten state, the viscosity of the blend will increase, making extrusion difficult, or the extrudate will shrink significantly during vulcanization. This turned out to be a problem.

(Means for Solving the Problems) That is, the present invention provides a blend of an acrylic elastomer and a polyvinylidene fluoride resin, in which the polyvinylidene fluoride resin is used as a powder that passes through a sieve of 50 mesh or more. The present invention provides a processing method that satisfies both the molding method and the physical properties after vulcanization by mixing at a temperature lower than the melting point of the resin and processing and molding at a temperature lower than the melting point of the polyvinylidene fluoride resin.

Acrylic elastomer refers to a polymer whose main component is ethyl acrylate. Acrylic elastomer is usually blended with polyvinylidene fluoride resin to obtain a high level of fuel oil resistance. Ethylene O - 15% by weight, vinyl carboxylate 0 - 40% by weight
, 0 to 20% by weight of acrylonitrile, and 60 to 100% by weight of alkoxyalkyl acrylate. A preferred acrylic elastomer is one obtained by polymerizing 80 to 100% by weight of alkoxyalkyl acrylate, 0 to 20% by weight of acrylonitrile, 5% by weight of ethylene θ and 5% by weight of vinyl fatty acid. A more desirable acrylic elastomer is one obtained by polymerizing 80 to 100% by weight of alkoxyalkyl acrylate and 0 to 20% by weight of acrylonitrile, and a particularly desirable acrylic elastomer is one formed by polymerizing 85 to 95% by weight of alkoxyalkyl acrylate and 5 to 1% by weight of acrylonitrile.
It is obtained by polymerizing 5% by weight.

The vinylidene fluoride resin used in the present invention refers to polyvinylidene fluoride and a copolymer of vinylidene fluoride and other copolymerizable monomers, and other copolymerizable monomers include hexafluoropropylene, pentafluoropropylene, and Fluoroethylene, trifluorochloroethylene, tetrafluoroethylene vinyl fluoride, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether), other olefins, acrylic esters, etc., and one or more of these are common. Used in polymerization.

It is necessary for the polyvinylidene fluoride resin powder to pass through a sieve with a mesh size of 50 or more, and if the powder becomes coarser than this, the performance of the blend will deteriorate, which is undesirable. A desirable particle size of the powder is one that allows it to pass through a sieve of 250 mesh or more, and more preferably one that allows it to pass through a sieve of 300 mesh or more.

It is essential that the blending temperature of the acrylic elastomer and polyvinylidene fluoride resin is lower than the melting point of the polyvinylidene fluoride resin, preferably at least 30° C. 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.

If blended at a temperature higher than the melting point of polyvinylidene fluoride resin, the viscosity of the blend will increase significantly, making it difficult to process, and distortion may remain during processing and molding of the blend, resulting in poor dimensional stability during vulcanization. Lost.

As mentioned above, especially in the case of vulcanization of a blend of an acrylic elastomer without copolymerizing a crosslinking monomer and a polyvinylidene fluoride resin, the crosslinking agent used is a peroxide.

When producing acrylic elastomers, we copolymerize crosslinkable monomers that can be crosslinked with a special crosslinking agent.
Crosslinking is often carried out using the crosslinking agent.

In this case, 0.1 to 100 parts by weight of the crosslinking monomer is added to 100 parts by weight of the monomer components of the acrylic elastomer.
Using acrylic elastomer copolymerized with 10 parts by weight,
The acrylic elastomer can be crosslinked using a crosslinking agent corresponding to this crosslinkable monomer.

Examples of crosslinking monomers include diene compounds, epoxy group-containing ethylenic compounds, carboxyl group-containing ethylenic compounds, active halogen-containing ethylenic compounds, etc. The present invention is effective as long as it can be used, and the type of crosslinking monomer is not particularly limited.

When the crosslinking monomer is a diene compound, peroxides and vulcanizing agents used for natural rubber are generally used, and when the crosslinking monomer is an ethylenic compound containing an epoxy group, curing agents used for epoxy resins are used. , organic ammonium carboxylate, dithiocarbamate, quaternary ammonium salt,
Guanidines, sulfur compounds, alkaline earth metal hydroxides, lead oxides, and zinc oxides can be used, and in the case of active halogen-containing ethylenic compounds, ammonium organic carboxylates, alkali metal salts of organic carboxylic acids, and sulfur compounds can be used. A combination of can be used.

In the case of vulcanization using a peroxide, those commonly used for crosslinking rubber can be used as peroxides, such as di-t-butyl peroxide, t-butyl peroxide, etc., but are not particularly limited.
-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.

Although the amount of peroxide is not limited, it is usually about 1 to 10 parts by weight per 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 parts by weight per 100 parts by weight of acrylic elastomer. The appropriate amount is less than 1 part by weight.

Excess polyfunctional monomer is undesirable because it causes the crosslinked product to lose its flexibility. As polyfunctional monomers, trimethylolpropane trimethacrylate and trimethylolpropane triacrylate are the most effective, and triallyl isocyanurate is the most effective polyfunctional monomer. , triallyl cyanurate, triallyl trimellitate, trimethylolpropane triacrylate), 1.
6-hexanediol acrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, diallyl phthalate, 1,2-polybutadiene, etc. are also applicable.

In addition, it is effective to use a radical scavenger or a thiourea derivative in combination with peroxide crosslinking in order to balance the physical properties of the crosslinked product, and the radical scavenger should be used in an amount of 3 parts by weight or less per 100 parts by weight of the acrylic elastomer. It is desirable to use 5 parts by weight or less of the thiourea derivative. If a large amount of the radical scavenger is used, peroxide will be consumed and the purpose of balancing the physical properties of the crosslinked product will be lost. If a large amount of thiourea derivatives are used, the opposite effect will occur in that the physical properties of the crosslinked product will deteriorate. It is desirable to use them alone or in combination within the above range.

As the radical scavenger, compounds generally used as polymerization inhibitors or anti-aging agents, sulfur or sulfur-containing compounds are used, and typical examples include phenothiazine, 2-6
Examples include 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 application of the blend.

In addition, nitrile rubber, hydrogenated nitrile rubber, epichlorohydrin rubber, ethylene propylene rubber,
It is also possible to blend butyl rubber, fluororubber, etc.

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

As the plasticizer, those that do not impair the purpose of the present invention, i.e.,
Examples of materials having affinity for the composition include α-olefin oligomers, polybutenes, polyethers, and polyesters.

Furthermore, if desired, it is also possible to mix it with other rubbers, such as various other rubbers with excellent fuel oil resistance.

(Function) According to the processing method of the present invention, the blend can be processed extremely easily in the state of unvulcanized rubber, and a molded product of unvulcanized rubber with a smooth blended surface and little internal distortion can be produced. Excellent dimensional stability. By the vulcanization method of the present invention, a vulcanizate that exhibits the blending effect of polyvinylidene fluoride resin, fuel oil resistance, and solvent crack growth resistance can be obtained.

(Example) (1)-1 Production of acrylic elastomer A 43 kg of water and 4 kg of acrylonitrile were placed in the 1301 autoclave.
, 36 kg of methoxyethyl acrylate, 700 each of Denka Poval B-05 and B-17 as polyvinyl alcohol
g, 60 g of sodium acetate, 2 g of ferric sulfate, 4 g of ethylenediaminetetraacetic acid, and 90 g of a cocatalyst were added and mixed with stirring, and the internal temperature of the autoclave was brought to 45°C. The air above the autoclave was replaced with nitrogen.

Separately, an aqueous polymerization initiator solution was injected through an injection port to allow polymerization to proceed, and the injection was completed in 12 hours. A sodium sulfate aqueous solution is added to the produced polymer emulsion to solidify the polymer, which is washed with water, dehydrated and dried, and the polymer is made into acrylic elastomer A.
I tried it as a.

+11-2 Production of acrylic elastomer B 130
2120g of polyvinyl alcohol in autoclave 1
An aqueous solution prepared by dissolving 86 g of sodium acetate and 65 kg of sodium acetate was added, and while stirring, 8.6 kg of vinyl acetate and 34.5 kg of 2-methoxyethyl acrylate were added.
6 kg, 160 g of chrycidyl methacrylate, and 480 g of allyl glycidyl ether were added and emulsified, and after purging the inside of the autoclave with nitrogen gas, ethylene monomer was pressurized from the top. Ethylene pressure is 45k at polymerization temperature of 55℃
g/d. Separately, a polymerization initiator aqueous solution was added several times through an injection port, the polymerization was stopped in about 10 hours, the monomer was removed, and the coagulation with a 3% aqueous solution of boraxox was performed.
The dehydrated and dried polymer was used as acrylic elastomer B.

(2) Polyvinylidene fluoride resin As shown in Table 1, polyvinylidene fluoride 5oletl 1010 (melting point 162°C) manufactured by Trubay was freeze-pulverized and then separated using a sieve. Samples B, C, and D shown in Table 1 were
I got it.

Table 1 (3) Acrylic elastomer (raw rubber) using Blend 31 kneader
1400 g of raw rubber was poured into the base, and after 1 minute of strands, the polyvinylidene fluoride resin shown in Table 2 and all the ingredients except the vulcanizing agent were added, kneaded for 3 minutes, pounded for 3 minutes, and then discharged. The kneading temperatures are shown in Table 2.

The discharged blend is sheeted with a 10-inch roll at 40°C, left to cool, and then extruded again at 40°C (4) Using an extruder with L/D = 400m5150wm, cylinder temperature is input to the rotor/middle part/die installation. Mouth/Die head 50/70/90/110℃Screw rotation 20rpm
A hose with an inner diameter of 9D and an outer diameter of 1311 was extruded.

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

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

(7) Physical properties After being left at room temperature for one day after vulcanization, JISK630
1, various physical properties were measured. The results are shown in Table 2.

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

Mixed solvent with a volume ratio of 40 isooctane and 60 toluene
Based on samples kept at 0℃ and measured for shrinkage of extruded products, JISI
Punch out a dumbbell and place JIS K6301 in the center.
Cuts were made in the same manner as in the Demarcia bending test, and after setting the stretching ratio to a predetermined value, the sample was immersed in a mixed solvent and the time until cutting was measured.

Table 3 (Note) The ingredients used in the Examples and Comparative Examples are as follows.

1) Uni II: Manufactured by Iyal Co., Ltd., Naugard 445
2) Tokai Carbon Co., Ltd., l5AF-HS carbon black 3) Asahi Carbon Co., Ltd., FT carbon black 4) Adeka Argus Co., Ltd., ester plasticizer 5) Nippon Petrochemical Co., Ltd., polybutene 6) Mitsui Petrochemical Co., Ltd., Ethylene propylene rubber 7) Trimethylolpropane trimethacrylate 8) Trimethylthiourea 9) Peroxide Perhexa V-10, manufactured by Nippon Oil & Fats Co., Ltd.) Organic sulfur compound patent applicant, manufactured by Toyo Kagaku Co., Ltd. Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] Processing and molding the blend obtained by mixing an acrylic elastomer and a polyvinylidene fluoride resin that passes through a sieve of 50 mesh or more at a temperature lower than the melting point of the polyvinylidene fluoride resin at a temperature lower than the melting point of the polyvinylidene fluoride resin. A method for processing a blend of acrylic elastomer and polyvinylidene fluoride resin, characterized by: