JPS5934729B2 - Method for producing mixed elastomer-vulcanized compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a useful method for preparing mixed elastomeric vulcanized blends of fluoroelastomers and carboxyl-containing acrylic elastomers.

In the technical field of heat-resistant elastomers such as fluoroelastomers and acrylic elastomers, there is a need for elastomers that exhibit good processability during kneading and molding, have satisfactory heat resistance, and are priced accordingly. In contrast, it has been proposed to use a fluoroelastomer and an acrylic elastomer as a mixed elastomer (Japanese Patent Application Laid-open No. 40558/1983).

However, it is known that when elastomers with completely different properties are mixed, a uniform mixed state cannot be obtained in many cases, and even in the most uniformly mixed state, microscopic phase separation occurs. It is often seen that the physical properties of the vulcanized product of a phase-separated elastomer mixture are inferior to those of the vulcanized product of each elastomer alone, and this also applies to the case of a mixed elastomer of fluoroelastomer and acrylic elastomer. Not an exception. The present inventor has developed an acrylic elastomer that uses a carboxyl group-containing acrylic elastomer to form crosslinks between the mixed elastomer and the fluoroelastomer, thereby preventing the deterioration of the physical properties of the vulcanizate due to phase separation. (Japanese Patent Application No. 7365/1983).

Conventionally, these mixed elastomers were kneaded using a roll-type rubber kneader or a Pampari kneader, but since it takes a long time to completely homogenize these two elastomers, the kneading time is different from each other. It took about twice as long as it would have otherwise.

In addition, since the mixed elastomer was kneaded for such a long time, it was strongly affected by heat and often had a tendency to cause scorch. In order to avoid such time loss and thermal influence, a method is often used in which an acrylic elastomer and a fluoroelastomer are mixed in a latex state and salted out to form a mixed elastomer.

The present invention uses a latex prepared by mixing a crosslinking agent for acrylic elastomers containing carboxyl groups into acrylic elastomer latex containing carboxyl groups, thereby combining fluoroelastomer latex and acrylic elastomer latex containing carboxyl groups in a latex state. This makes it possible to blend. The present invention was developed because it was not possible to unevenly distribute the acrylic elastomer crosslinking agent only in the acrylic elastomer phase by ordinary kneading means. The present invention enables the crosslinking agent for carboxyl group-containing acrylic elastomer to be unevenly distributed only in the carboxyl group-containing acrylic elastomer phase by mixing the crosslinking agent for carboxyl group-containing acrylic elastomer during the production of carboxyl group-containing acrylic elastomer latex. That is. The following two methods can be used to mix a polyepoxy compound as a crosslinking agent into an acrylic elastomer. 1. A method of polymerizing a carboxyl group-containing acrylic elastomer in the presence of a crosslinking agent.

2. A method of mixing a crosslinker emulsion with a carboxyl group-containing acrylic elastomer latex.

Whichever method is used, it is a necessary condition that the epoxy compound is sufficiently dissolved in the particles of the acrylic elastomer latex in order to avoid any adverse effects when blended. Therefore, it is desirable that the epoxy compound used here be insoluble in water. In addition, in the method 2 mentioned above, in order to sufficiently dissolve the epoxy compound into the latex particles, (1) After mixing the epoxy compound emulsion and the latex, heat the mixture at 30 to 70°C.
Aging for 120 minutes (2) After mixing, add about 5% NaC
It is necessary to take measures such as adding l and ripening. The mixed elastomer includes 1 to 99 parts (by weight, the same applies hereinafter) of a fluoroelastomer, preferably 40 to 95 parts, and 99 to 1 part, preferably 60 parts of a carboxyl group-containing acrylic elastomer.
5 parts, and other elastomers may be mixed as long as they do not impede the purpose of the present invention. As the fluoroelastomer, for example, vinylidene fluoride-hexafluoropropylene copolymer is particularly preferably used.
0:15 to 40 mol% copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, etc. are used alone or in combination. In addition to this, copolymers of dichlorodifluoroethylene, perfluoroacrylic acid derivatives, perfluorovinyl ether, and vinylidene fluoride can also be used.

The carboxyl group-containing acrylic elastomer contains 50 to 99.9% by weight of acrylic ester and 20 to 0.0% by weight of carboxyl group-containing monomer. It consists of a copolymer with 1% by weight.

Examples of acrylic esters include alkyl acrylates in which the alkyl group has 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, n- or isopropyl acrylate, n- or isobutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate. , methoxymethyl acrylate, methoxyethyl acrylate, 2-ethoxyethyl acrylate, etc., each having 1 to 4 alkyl groups and alkylene groups.
Alkoxyalkyl acrylates having 5 carbon atoms are used, and ethyl acrylate is particularly preferred. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, vinyl acetic acid, 4-vinylbenzoic acid, 4-allylbenzoic acid, and styryl acetic acid, with acrylic acid and methacrylic acid being particularly preferred. In the carboxyl group-containing acrylic elastomer, 30 to 0% by weight of other monomers that can be copolymerized with acrylic esters such as styrene, acrylonitrile, and vinyl acetate and the carboxyl group-containing monomer can also be copolymerized. .

Examples of carboxyl group-containing acrylic elastomers include ethyl acrylate-acrylic acid copolymers and ethyl acrylate-methacrylic acid copolymers, particularly preferably 95-99.5:5-O. A 5 mol % copolymer, an ethyl acrylate-methyl acrylate mono-acrylic acid terpolymer, and the like are used. Vulcanizing agents for acrylic elastomers include water-insoluble epoxy equivalents having at least two epoxy groups in the molecule and having an equivalent weight of about 70 to 1000.
polyepoxy compounds are used. Examples of polyepoxy compounds include 2,2-bis(47-glycidyloxyphenyl)propane, 2,2-bis(4'-glycidyloxyphenyl)hexafluoropropane, phthalic acid diglycidyl ether, and novolac polyglycidyl. One or more types of ether, bisphenol A/epichlorohydrin condensate, etc. are used, and 2,2-bis(4'-glycidyloxyphenyl)propane is particularly preferred. These polyepoxy compounds are used in an amount of 0.1 to 20 parts, preferably 0.5 to 5 parts, per 100 parts of mixed elastomer.
Used as a percentage. The following two methods can be considered for incorporating these polyepoxy compounds into the acrylic elastomer latex.

During one polymerization, 0.1 to 20 parts of the above crosslinking agent is dissolved in a mixed solution of acrylic acid ester, etc., and then JP-A-51-144
Polymerization is performed according to a known method such as No. 484 to obtain an acrylic elastomer latex containing a crosslinking agent.

2. Crosslinking agent for acrylic elastomer as it is or after dissolving it in an organic solvent such as acetone or benzene, add 1 to 30 parts of crosslinking agent and 1 part of emulsifier (sodium dodecyl sulfate, polyoxyethylene dodecyl ether, etc.) to 100 parts of water. A cross-linking agent emulsion was prepared with ~2 parts, and this was mixed with an acrylic elastomer emulsion (10 parts as rubber content).
0 parts), 0.1 to 20 parts of the crosslinking agent emulsion is added as the weight of the crosslinking agent to obtain a crosslinking agent-containing acrylic elastomer latex.

Acrylic elastomers, such as active halogen-containing acrylic elastomers and epoxy-containing acrylic elastomers, which do not particularly require a crosslinking agent, may be simply blended as a latex with a fluoroelastomer without any particular problem. but,
Acrylic elastomers that require a separate crosslinking agent, such as carboxyl-containing acrylic elastomers, cannot be simply latex blended. This is because it has been found that when an acrylic crosslinking agent is added to a blended elastomer, this crosslinking agent also mixes into the fluoroelastomer phase, adversely affecting physical properties and processability. The present invention was developed because it was not possible to unevenly distribute the crosslinking agent for acrylic elastomer only in the acrylic elastomer phase by ordinary kneading means. This crosslinking agent for acrylic elastomer is sufficiently dissolved in the acrylic elastomer latex, which has a great effect on improving the physical properties during blending.
The crosslinking agent-containing acrylic elastomer latex and fluoroelastomer latex have an elastomer composition of 1 to 99.5 parts of fluoroelastomer, preferably 40 parts of fluoroelastomer.
~99.5 parts, 0.5 to 99 parts of acrylic elastomer,
Latexes are mixed in a predetermined ratio, preferably 60-0.5 parts, aged for 1 to 4 hours, salted out, washed with water, and dried to obtain a blended elastomer. Vulcanizing agents for fluoroelastomers include aromatic, aliphatic or cycloaliphatic groups substituted with 2 to 4 active hydrogen-containing groups such as carboxyl groups, hydroxyl groups, amino groups, imino groups, mercapto groups, etc. A compound is used.

Examples of such compounds include terephthalic acid, P-hydroxybenzoic acid, dihydroxynaphthalene, tetrahydroxyanthracene, 2,2'-hydroxybiphenyl, 4,4'hydroxybiphenyl, catechol, P-aminophenol, P-phenylene. Diamine, terephthalaldehyde, 2-mercaptobenzimidazole, 4.
4'-diaminodiphenylmethane, phthalic acid imide, bisphenol A1 bisphenol S1 bisphenol A
Fl4・4! -dihydroxybenzophenone and the like. Among these vulcanizing agents, compounds having the following general formula are preferably used.

Here, X and Y are carboxyl group, hydroxy group,
A substituent containing active hydrogen such as an amino group, an imino group, or a mercapto group, m and n are integers of 1 or more, and A is a carbonyl group, a sulfinyl group, an alkylene group,
The phenyl group is a perfluoroalkylene group, an alkylidene group or a perfluoroalkylidene group, and the phenyl group may be further substituted with a substituent containing no active hydrogen such as a halogen, a nitro group, an alkoxy group, an ester group, etc.

Particularly preferred X. '-0? The agent is a polyhydroxy-substituted compound, especially a bisphenol type compound, such as hexafluoroisopropylidene bis(4-hydroxyphenyl), which is called bisphenol AF, and isopropylidene, which is called bisphenol A. Bis(4-hydroxyphenyl), 4,4'-dihydroxy-diphenyl sulfone, also known as bisphenol S, 2,2
'-dihydroxy-biphenyl, 1,4-dihydroquinone, and the like.

These vulcanizing agents for fluoroelastomers are used in an amount of 0.1 to 10 parts, preferably 0.5 parts, per 100 parts of mixed elastomer.
If a vulcanizing agent is used in a proportion of ~3 parts, the desired vulcanizing effect will not be obtained if a proportion smaller than this is used, while if it is used in a larger proportion, the rubber will become harder, and as a result, the elasticity and elongation of the rubber will decrease. Not only is this loss, but the vulcanization rate also decreases.

The decrease in vulcanization rate is due to the vulcanizing agent acting as an acid,
This occurs when a large amount is used compared to a vulcanization accelerator that acts as an alkali. As the vulcanization accelerator, those belonging to the following categories are used.

Those in the first and second categories are shown in the following general formulas. Here, R1 to R4 are an alkyl group having 1 to 20 carbon atoms, a fluoroalkyl group, an aralkyl group, a polyoxyalkylene group, an aryl group, etc., and X is a halogen, a hydroxy group, a carboxyl group, a carbonate group,
Examples of such quaternary ammonium salts include octadecyldimethylbenzylammonium chloride and octadecyldimethylbenzylammonium acetate, and examples of quaternary phosphonium salts include triphenylbenzylphosphonium chloride,
Examples include tricyclohexylbenzylphosphonium chloride.

Instead of the quaternary phosphonium halide, an equimolar mixture of a tertiary amine represented by the formula RlR2R3N and a halide represented by the formula R4X' (R1 to R4 are the same as defined above and X' is a halogen) is used. It can also be used for Those belonging to the third category have the general formula RN-
It is a nitrogen-containing heterocyclic compound adduct represented by RlX (where R is a group forming a heterocyclic ring together with N, and R1 and X are the same as defined above), such as lauryl pyridinium bromide, lauryl Examples include isoquinolinium bromide and benzylisoquinolinium chloride.

A mixture of a nitrogen-containing heterocyclic compound represented by the formula RN and a halide represented by the formula R, X' (R.Rl and X are as defined above), such as isoquinoline and benzyl chloride or lauryl bromide. Equimolar mixtures of Nada can also be used equally. Belonging to the fourth category are polyamine compounds having an NH-C-NH bond, such as guanidine or guanidine, such as methylguanidine, acetylguanidine, diphenylguanidine, di-10-tolylguanidine, 0-tolylbiguanide, etc. alkyl, acyl, aryl, aralkyl substituents and general formula R5-NH-C-NH-C-NH2 (wherein
R5 is hydrogen, alkyl, aryl, or aralkyl group).

The fluoroelastomer and acrylic elastomer used in the present invention clearly have different crosslinking reactions, so it is rare that the same vulcanization rate and density can be obtained with the same vulcanization accelerator. I can't bite.

Therefore, when using these vulcanization accelerators, it is preferable to vary the accelerator concentration in each elastomer or to use two or more types of accelerators in combination. Vulcanization accelerator: 0.1 to 10 per 100 parts of mixed elastomer
Used as a percentage. If the proportion is less than this, the desired vulcanization promoting effect cannot be obtained, while if the proportion is greater than this, the vulcanization rate will be too fast, causing problems in terms of moldability. The vulcanization system also contains a vulcanization accelerating aid consisting of a metal oxide or hydroxide in order to accelerate the vulcanization of each mixed elastomer and provide aging stability to the fluoroelastomer.

Examples of metal oxides include divalent metal oxides such as magnesium oxide, zinc oxide, lead oxide, and calcium oxide;
Examples of metal hydroxides include magnesium hydroxide,
Examples include hydroxides of divalent metals such as zinc hydroxide and calcium hydroxide. One or more of these metal oxides or hydroxides are used in an amount of 1 to 40 parts, preferably 1 to 20 parts, per 100 parts of the mixed elastomer. In addition, weak acid salts of metals such as sodium, potassium, and barium, such as carbonates, stearates, and benzoates, can also be used in combination with the divalent metal oxides or hydroxides.

In addition to the above-mentioned vulcanization system components, ammonia or a hydrogen acid addition salt of amines is used as a vulcanization rate regulator.

As the amines used like ammonia, any of primary amines, secondary amines, and tertiary amines can be used, and they may be not only monoamines but also polyamines. Specifically, primary amines such as laurylamine, aniline, and guanidine, di-n-butylamine, diisobutylamine, di-0-tolylguanidine,
Examples include secondary amines such as diphenylguanidine, and tertiary amines such as triethylamine and pyridine. Also,
Examples of the hydrogen acid include inorganic hydrogen acids such as hydrochloric acid, sulfuric acid, boric acid, and ferricianic acid, and organic hydrogen acids such as benzoic acid.

Examples of hydrogen acid addition salts of ammonia or amines include ammonium benzoate, ammonium sulfate, laurylamine hydrochloride, aniline hydrochloride, di-n-butylamine hydrochloride, diisobutylamine hydrochloride, triethylamine hydrochloride, and pyridine hydrochloride. , di-0-tolylguanidine hydrochloride, diphenylguanidine hydrochloride, ammonium tetrafluoroborate, di-0-tolylguanidine tetrafluoroborate, ammonium ferricyanate, monodi-0-tolylguanidine ferricyanate, boron Examples include dicatechol di-0-tolylguanidine.

These hydrogen acid addition salts of ammonia or amines are
Mixed elastomer - O. per 100 parts. It is used in a proportion of 0.01 to 20 parts. If the proportion used is less than this, no scotch prevention effect will be observed, and if it is too large, vulcanization tends to be extremely slow. After adding fillers, pigments, porous substances, etc., which are generally known as compounding agents for rubber, to the elastomer and each component of the vulcanization system as necessary, the mixture is mixed with an arbitrary mixing device, such as two rolls for kneading rubber. , mix each component using a Banbury mixer or the like.

Prepare the elastomer vulcanization formulation. Since this mixture has appropriate viscoelasticity, it is easier to perform mixing and extrusion operations than when the fluoroelastomer is used alone, and is therefore superior in processability. Vulcanization is carried out at a temperature of about 150 to 200°C for about 1 to
This is done by heating for 30 minutes.

This vulcanization is carried out using a conventional rubber molding press, extruder, or the like. If a vulcanizate with excellent heat resistance and dimensional stability is desired, it is preferable to further post-vulcanize at a temperature of about 170 to 240° C. for about 1 to 48 hours. The vulcanizate obtained by vulcanizing the elastomer vulcanizate according to the present invention has significantly higher physical properties, especially compression, compared to the case where other types of acrylic elastomers are mixed with fluoroelastomers. It shows an excellent value in terms of permanent deformation.

Therefore, vulcanizates of mixed elastomers of other types of acrylic elastomers and fluoroelastomers are too deformed due to heat aging and cannot be used, such as in fields such as valve stem seals and O-rings. It can also be used effectively.

Of course, in addition to these new fields of application, it can also be effectively used in conventional fields of use of heat-resistant rubber, such as oil seals, gaskets, and tubes. Next, the effects of the present invention will be explained with reference to Examples.

Example 1 (a) Step of producing fluoroelastomer latex: In an autoclave, 100 parts of water, 0.75 parts of acetone, and 0.0 parts of soap (FS-1110 manufactured by Neos) were added.
After adding 14 parts of hexafluoropropylene and completely purging the autoclave with nitrogen, 21.9 parts of hexafluoropropylene and O. 2 parts were charged and the autoclave was maintained at 70°C to start polymerization.

Then, 50 parts of vinylidene fluoride was charged over about 3 hours after the start of polymerization.

The obtained fluoroelastomer latex was approximately 327/
1 of vinylidene fluoride-hexafluoropropylene (85:15 mol%) copolymer, the viscosity (
MLN24. lO) was 58.

(b) Step of producing a carboxyl group-containing acrylic elastomer latex by mixing a polyepoxy compound: 200 parts of water, 1 part of sodium dodecyl sulfate, and 3 parts of polyoxyethylene dodecyl ether are charged into an autoclave, and then ethyl acrylate is added. 99 parts of methacrylic acid, 0.02 parts of dodecylmercaptan, and 5 parts of 2.2-bis(4'-glycidyloxyphenyl)propane were charged.

After maintaining the liquid temperature at 50° C. and thoroughly purging with nitrogen, 0.1 part of ammonium persulfate and 0.1 part of sodium bisulfite were added to initiate polymerization. The polymerization was completed by stirring for about 1 hour while maintaining the temperature at about 60°C. The concentration of the obtained carboxyl group-containing acrylic elastomer latex was approximately 3
It was 25t/l.

(c) A step of mixing the fluoroelastomer latex obtained in step (a) and the acrylic elastomer latex obtained in step (b), followed by coagulation and drying: step (a)
Fluoroelastomer latex obtained in step 5
) was mixed with the carboxyl group-containing acrylic elastomer latex obtained in (1) at a volume ratio of about 2:1, and then this mixed latex solution was poured into 15% saline solution at about 80° C. for coagulation.

A mixed elastomer was obtained by washing this coagulated product with water and drying it. (d) The mixed elastomer obtained in step (c) contains (1) an aromatic, aliphatic or alicyclic compound substituted with two or more active hydrogen-containing groups, (2) a quaternary ammonium salt, a quaternary ammonium salt, and a quaternary ammonium salt. Phosphonium salts or guanidines, (3)
Step of mixing metal oxide or metal hydroxide and (4) hydrogen acid addition salt of ammonia or amines: Step (c
), 15 parts of HAF carbon, 10 parts of MT carbon, 4 parts of calcium hydroxide
．． 2 parts, magnesium oxide 2.1 parts, 2.2 bis(4'
-Hydroxyphenyl)hexafluoropropane 1.4
parts, stearic acid 1 part, 4,4bis(4-α·α-dimethylbenzyl)diphenylamine 2 parts, octadecyl-
0.8 part of dimethylbenzylammonium chloride was kneaded on a roll mill.

The mixed elastomer vulcanized compound obtained in this way was
Primary vulcanization was performed at 90°C for 7 minutes, followed by vulcanization at 175°C for 2 minutes.
Table 1 shows the characteristic values of the products subjected to secondary vulcanization for 4 hours.

Example 2 (a) Process: The same procedure as in Example 1 was carried out.

Step (b): The reaction was carried out without the 2,2-bis(4'-glycidyloxyphenyl)propane mixed in in Example 1, and the carboxyl group-containing acrylic elastomer latte without the polyepoxy compound was mixed. Generate Tux.

On the other hand, 2,2bis(4'-glycidyloxyphenyl)
Add 10 parts of benzene to 20 parts of propane, pour this into a solution of 70 parts of water, 1 part of sodium dodecyl sulfate, and 3 parts of polyoxyethylene dodecyl ether, and stir to obtain an emulsion.

The emulsion thus obtained and the carboxyl group-containing acrylic elastomer latex without the above-mentioned polyepoxy compound mixed therein are mixed in a volume ratio of about 12
．． They were mixed at a ratio of 5:1 and aged at 70°C for 2 hours.

(c) Step: The acrylic elastomer latex obtained in step (a) and the fluoroelastomer latex obtained in step (b) were mixed at a volume ratio of about 2:1, and the mixture was mixed with Example 1. Treated in the same way.

(d) Process: It was treated in the same manner as in Example 1.

The mixed elastomer vulcanized compound obtained in this way was
Table 1 shows the characteristic values obtained by performing primary vulcanization at 90°C for 12 minutes and then secondary vulcanization at 175°C for 24 hours.

Comparative example 1 (a) Process: The same procedure as in Example 1 was carried out.

Step (b): In step (b) of Example 2, a carboxyl group-containing acrylic elastomer latex was produced by removing the emulsion.

(c) Process: The same procedure as in Example 1 was carried out.

(d) Step: In Example 1, 3.5 parts of 2,2-bis(4'-glycidyloxyphenyl)propane was further added.

The mixed elastomer vulcanized compound obtained in this way was
Primary vulcanization was performed at 80°C for 14 minutes, followed by 2 vulcanization at 175°C.
Table 1 shows the characteristic values of the products subjected to secondary vulcanization for 4 hours.

Comparative example 2 (a) Process: The same procedure as in Example 1 was carried out.

Step (b): The same procedure as in Example 1 was carried out except that 4.3 parts of polyoxyethylene diglycidyl ether was used in place of the 2.2-bis(4'-glycidyloxyphenyl)propane used in Example 1.

(c), (d) steps: The same procedure as in Example 1 was carried out.

Comparative example 3 (a) Process: The same procedure as in Example 1 was carried out.

(b) Process: The same treatment as in Example 1 was performed except for the epoxy compound.

(c) Process: It was treated in the same manner as in Example 1.

(d) Step: 70 parts of the fluoroelastomer obtained in step (a) and (
HA
15 parts of F carbon, 10 parts of MT carbon, 4.2 parts of calcium hydroxide, 2.1 parts of magnesium oxide, 1.4 parts of 2,2bis(4'-hydroxyphenyl)hexafluoropropane, 1 part of steflic acid, 4・4 screws (4-α・α
2 parts of dimethylbenzyl) diphenylamine, 0.8 part of octadecyldimethylbenzyl ammonium chloride, 2 parts
- 3.5 parts of 2-bis(4'-glycidyloxyphenyl)propane was added and further kneaded.

The mixed elastomer vulcanized compound obtained in this way was
Table 1 shows the characteristic values obtained by performing primary vulcanization at 80° C. for 14 minutes, and then performing secondary vulcanization at 175° C. for 24 hours.

From the results in Table 1, compared to Comparative Examples 1 and 3, Examples 1 and 2 have lower hardness and greater elongation.

This means that the example retains more rubber-like characteristics. Further, in Comparative Example 2, the vulcanized sheet foamed, and physical property values could not be measured.

Claims (1)

[Claims] 1 (a) Step of producing a fluoroelastomer latex: (b) Step of producing a carboxyl group-containing acrylic elastomer latex formed by mixing a water-insoluble polyepoxy compound: (c) The above step ( A step of mixing the fluoroelastomer latex obtained in a) and the acrylic elastomer latex obtained in the step (b), followed by coagulation and drying: (d) to the mixed elastomer obtained in the step (c). and mixing a vulcanizing agent. 2 As the vulcanizing agent, (1) an aromatic, aliphatic or alicyclic compound substituted with two or more active hydrogen-containing groups, (2
) quaternary ammonium salts, quaternary phosphonium salts or guanidines, (3) metal oxides or metal hydroxides, and (
4) A method for producing a mixed elastomer vulcanized compound according to claim 1, characterized in that a hydrogen acid addition salt of ammonia or amines is used.