JPH0694520B2 - Ethylene elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an ethylene-based elastomer composition, and more specifically, it has excellent processing stability against early vulcanization before vulcanization. Epoxy group-containing ethylene-based elastomer vulcanized composition having storage stability and giving a vulcanized product excellent in mechanical properties and compression set without post-vulcanization for a long time Is.

<Prior Art> It has been customary to use polyamine, diamine carbamate, ammonium organic carboxylate, dithiocarbamate or the like as a vulcanization system for an elastomer containing an epoxy group. However, when polyamines and diamine carbamates are used, the vulcanization rate is high, so
There is a drawback that scorch is easy in the kneading process, and when using ammonium organic carboxylate and dithiocarbamate, the vulcanization rate is relatively slow, so a stable compound for scorch can be obtained. However, there is a drawback in that post-vulcanization must be carried out for a long time in order to obtain good compression set.

Various vulcanization methods for solving these drawbacks have been proposed. For example, JP-A-55-145727 discloses a vulcanization system using a phthalic acid anhydride and a specific imidazole compound for an epoxy group-containing elastomer. Is disclosed,
JP-A-57-177044 and JP-A-57-177045 disclose vulcanization systems using a guanidine compound and a sulfur or sulfur compound for an epoxy group-containing elastomer. However, while these vulcanization systems are stable against scorch, they have the drawback that post-vulcanization must be carried out for a long time in order to obtain good compression set.

Further, in JP-A-61-26620 and JP-A-61-235424, a compound having two or more carboxyl groups in a molecule or a polyvalent carboxylic acid is added to an epoxy group-containing elastomer such as acrylic rubber. A vulcanization system is disclosed which comprises the anhydride and a quaternary ammonium or quaternary phosphonium salt.

However, when these vulcanization systems are applied to the epoxy group-containing ethylene elastomer of the present invention, the vulcanization system equivalent to the conventionally known vulcanization system using a phthalic anhydride and a specific isidazole compound, or It was found in our study that it showed a lesser degree of effect.

<Problems to be Solved by the Invention> An object of the present invention is to improve each of the above-mentioned drawbacks and to have a fast vulcanization rate and a stable scorch property and storage stability before vulcanization. Moreover, it has excellent mechanical properties and physical properties such as compression set without post-vulcanization for a long time.
An object is to provide an ethylene-based elastomer composition containing an epoxy group.

<Means for Solving Problems> As a result of repeated studies on various vulcanization systems to improve these drawbacks, the present inventors have found that (A) (a) 50 to 85 mol% of ethylene, ( b) 50-15
Ethylene copolymer obtained by copolymerizing mol% of acrylic acid ester or methacrylic acid ester and (c) 1.0 to 8% by weight of unsaturated glycidyl ester with respect to the total of both components (a) and (b). On the other hand, (B) a compound containing two or more carboxyl groups in the molecule and / or an anhydride of a polycarboxylic acid, and (C) a quaternary ammonium salt or a quaternary phosphonium salt, D) By using a urea derivative compound and (E) a compound containing two or more imidodicarbonyl bonds in the molecule as a vulcanizing agent, the vulcanization rate is fast and stable before vulcanization. Has scorch and storage stability,
Moreover, it was found that a vulcanized product having excellent physical properties such as mechanical properties and compression set can be obtained without performing post-vulcanization for a long time.

The acrylic acid ester or methacrylic acid ester (b), which is a constituent component of the (A) ethylene-based copolymer in the present invention, is an ester composed of an alcohol having 1 to 8 carbon atoms, and more specifically, methyl acrylate. , Methyl methacrylate, n-butyl acrylate, n methacrylate
-Butyl, tert-butyl acrylate, tert-methacrylic acid
-Butyl, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and the like are exemplified, and these may be used alone or in combination of two or more.

The molar ratio of (a) ethylene to (b) acrylic acid ester or methacrylic acid ester is 50 to 85:50 to 15, preferably 58 to 80:42 to 20.

It is also possible to copolymerize the ethylene-based copolymer (A) of the present invention with a copolymerizable comonomer with other ethylene. Specific examples include isobutylene, styrene and its derivatives, vinyl acetate, halogenated olefins such as tetrafluoroethylene and hexafluoropropylene, and the like.

The ethylene-based copolymer (A) of the present invention is produced by a known method. For example, it can be produced by bulk polymerization, emulsion polymerization, or solution polymerization with a free radical initiator. A typical polymerization method is described in JP-B-46-45085. That is, it can be produced under the conditions of a pressure of 500 kg / cm ² or more and a temperature of 40 to 300 ° C. under a polymerization initiator that generates free radicals.

The ethylene-based copolymer (A) used in the present invention is obtained by copolymerizing the above-mentioned respective components, and has a melting index at 190 ° C. defined by JIS K6791 of 0.5 to 500 g / 10 minutes, preferably 0.5 to
Those in the range of 50g / 10 minutes are used.

(B) If the content of the acrylic acid ester or the methacrylic acid ester exceeds the upper limit value, the embrittlement point becomes high, which makes it difficult to use as an elastomer at low temperature. On the other hand, if the amount is lower than the lower limit, the crystallinity of the copolymer becomes high, so that sufficient elasticity as an elastomer cannot be obtained.

Examples of the unsaturated glycidyl ester (c) which is a constituent of the ethylene copolymer (A) in the present invention include glycidyl acrylate, glycidyl methacrylate and itaconic acid diglycidyl ester described in JP-B-46-45085. , Butenetricarboxylic acid triglycidyl ester, p-styrenecarboxylic acid glycidyl ester and the like are illustrated, and these may be used alone or in combination of two or more.

The amount of the unsaturated glycidyl ester (c) used is 1.0 to 8% by weight, preferably 1.5 to 5% by weight, based on the total amount of both components (a) and (b). If the content of unsaturated glycidyl ester exceeds the upper limit, the scorch resistance becomes poor, and if it is lower than the lower limit, a sufficient crosslinking effect cannot be obtained.

In the present invention, for these ethylene-based copolymers containing epoxy groups, (B) a compound containing two or more carboxyl groups in the molecule and / or an anhydride of a polycarboxylic acid and (C) A quaternary ammonium salt or quaternary phosphonium salt, a (D) urea derivative compound, and a compound (E) containing two or more imidodicarbonyl bonds in the molecule are added as a vulcanization system.

The compound (B) containing two or more carboxyl groups in the molecule used in the present invention is usually selected from saturated and unsaturated aliphatic compounds, aromatic compounds and low molecular weight polymers. It can also be used for compounds containing alicyclic, aromatic and heteroatoms in the main chain.

Representative compounds having two or more carboxyl groups in the molecule (B) that can be used in the present invention are as follows, but the compounds are not particularly limited thereto.

Examples of aliphatic compounds include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, octanedioic acid, dodecanedioic acid, tridecanic acid,
Tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, tartoluic acid, methyltartoluic acid, methylmalonic acid,
Ethylmalonic acid, tetramethylsuccinic acid, 2,2'-dimethylsuccinic acid, malic acid, α-methylmalic acid, α-oxyglutanic acid, α-oxyadipic acid, oxosuccinic acid,
Acetylmalonic acid, 2-acetylglutaric acid, β-hydroxyglutaric acid, maleic acid, citraconic acid, muconic acid, citric acid, tartaric acid, 1,2,3-propanetricarboxylic acid, 1,2,3-propenetricarboxylic acid, Examples include 1,2,5-pentanetricarboxylic acid, cystine, aspartic acid, glutamic acid, β-hydroxyglutamic acid, iminodiacetic acid, nitrilotriacetic acid, and ethylenediaminetetraacetic acid.

Examples of alicyclic compounds include cis 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,5-
Examples include cyclooctane dicarboxylic acid and hexahydroterephthalic acid.

Examples of aromatic compounds include phthalic acid, 3-methylphthalic acid, terephthalic acid, phthalonic acid, hydroxyterephthalic acid, hemipic acid, benzophenonedicarboxylic acid, phenylsuccinic acid, trimellitic acid, and pyromellitic acid.

Examples of the compound containing an aromatic in the main chain include 7,8-diphenyl-tetradecanedioic acid.

Examples of low molecular weight polymers include, but are not limited to, carboxylated polybutadiene at both ends, carboxylated butadiene-acrylonitrile at both ends, and carboxylic acid-containing liquid butadiene-acrylonitrile having a carboxyl group in the molecular chain.

Typical examples of the (B) polycarboxylic acid anhydride used in the present invention include the following.

Examples of the aliphatic carboxylic acid anhydrides include maleic anhydride, methylmaleic anhydride, succinic anhydride, glutaric anhydride, 2,2'-dimethylglutaric anhydride, 2,3-dimethylmaleic anhydride, and citraconic anhydride. , 1-dodecenylsuccinic anhydride, dichloromaleic anhydride, diglycolic anhydride, thiodiglycolic anhydride, glutaconic anhydride and the like.

Examples of aromatic and alicyclic carboxylic acid anhydrides are phthalic anhydride, diphenic anhydride, isatoic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 1,2- Examples thereof include cyclohexadicarboxylic acid anhydride, methylhexahydrophthalic anhydride, tetrachlorophthalic anhydride, and tetrobromophthalic anhydride.

Examples of the aliphatic long-chain dibasic acid anhydride include octadecyl diacid condensate, and examples of the long-chain dibasic acid anhydride containing an aromatic in the main chain include 7,8-diphenyl-tetradecane. Examples thereof include diacid condensates.

These compounds can be added and mixed at the time of the polymerization reaction of the elastomer or at the completion of the polymerization, or can be added and mixed together with other compounding agents such as a filler to the elastomer by a kneading machine usually used in the rubber industry. .

The compound (B) having two or more carboxyl groups in the molecule and / or the anhydride of polyvalent carboxylic acid used in the present invention is usually 0.1% by weight per 100 parts by weight of (A) ethylene copolymer. It can be used in a proportion of up to 30 parts by weight. The ratio of these compounds to the ethylene copolymer is selected as a preferable range from the viewpoints of vulcanization rate, mechanical properties of the vulcanizate, and compression set. Below this range, the vulcanization rate It is not possible to obtain a vulcanizate that can be practically used due to the remarkable decrease. On the other hand, if it exceeds this range, the vulcanization rate becomes extremely slow and it cannot be put to practical use. It is preferably 0.1 to 20 parts by weight.

The (C) quaternary ammonium salt and quaternary phosphonium salt used in the present invention are compounds represented by the following general formula.

R _{1 to} R ₄ in the above general formula have 1 to 1 carbon atoms such as alkyl, aryl, alkylaryl and polyoxyalkylene groups.
It is a hydrocarbon group having about 25 carbon atoms, or two or three of R _{1 to} R ₄ form a heterocyclic structure having a nitrogen atom or a phosphorus atom and about 3 to 20 atoms, In the heterocycle, at least two of all atoms are carbon and the rest are carbon, nitrogen or sulfur atoms.

X is an anion derived from an inorganic or organic acid in which acidic hydrogen is bonded to halogen or oxygen, and is preferably Cl, Br, I, HSO ₄ , H ₂ PO ₄ , R ₅ COO, R ₅ OSO ₂ , R ₅ SO, R
Examples include anions such as ₅ OPO ₃ H (R ₅ is the same hydrocarbon group as R _{1 to} R ₄ described above).

Specific examples of the quaternary ammonium salt include tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide,
Tetrabutylammonium iodide, n-dodecyltrimethylammonium bromide, cetyldimethylbenzylammonium chloride, methylcetyldibenzylammonium bromide, cetyldimethylethylammonium bromide, octadecyltrimethylammonium bromide, cetylpyridinium chloride, cetylpyridinium bromide, 1,3 -Diaza-bicyclo (5,4,0)
Undecene-7-methylammonium methosulfate, 1,8-diaza-bidichro (5,4,0) undecene-7-
Benzyl ammonium chloride, cetyl trimethyl ammonium alkylphenoxy poly (ethyleneoxy)
Ethyl phosphate, cetylpyridinium sulphate,
Examples thereof include tetraethylammonium acetate, trimethylbenzylammonium benzoate, trimethylbenzylammonium paratoluene sulfonate, trimethylbenzylammonium borate and the like.

Examples of the quaternary phosphonium salt include triphenylbenzylphosphonium chloride, triphenylbenzylphosphonium iodide, triphenylmethoxymethylphosphonium chloride, triethylbenzylphosphonium chloride, tricyclohexylbenzylphosphonium chloride, trioctylmethylphosphonium dimethylphosphate, tetra Examples include butylphosphonium bromide and trioctylmethylphosphonium acetate.

These (C) quaternary ammonium salts or quaternary phosphonium salts may be used either individually or in combination of two or more, and are usually used in an amount of 0.1 to 100 parts by weight of the (A) ethylene-based copolymer.
Used in a proportion of up to 10 parts by weight. The use ratio of these compounds to the ethylene copolymer is selected as a preferable range from the viewpoints of vulcanization rate, processing stability, storage stability, mechanical properties of the vulcanizate, compression set, etc. However, if it is less than this range, vulcanization hardly progresses, while if it is used at a ratio exceeding this range, the vulcanization rate becomes extremely high and the processing stability and storage stability are impaired. It is preferably 0.1 to 5 parts by weight.

Examples of the (D) urea derivative compound used in the present invention include urea, methylurea, ethylurea, propylurea, N-
N'dimethylurea, N-N'diethylurea, N-N'dipropylurea, N-methyl-N'ethylurea, N-ethyl-N '
Propylurea, N-methyl-N'phenylurea, N-N'diphenylurea and the like can be mentioned.

These (D) urea derivative compounds can be used alone or in combination of two or more, and (A) ethylene-based copolymer 10
Usually, 0.1 to 20 parts by weight is used in a proportion of 0 parts by weight.
The use ratio of these compounds to the ethylene-based copolymer is selected as a preferable range from the viewpoints of vulcanization rate, processing stability, storage stability, mechanical properties of the vulcanizate, compression set, etc. However, if it is less than this range, compression set deteriorates, and if it exceeds this range, the effect cannot be expected to increase. It is preferably 0.1 to 10 parts by weight.

The compound (E) containing two or more imidodicarbonyl bonds in the molecule used in the present invention is a compound containing two or more imidodicarbonyl bonds represented by the following general formula in the molecule. Is isocyanuric acid, barbital,
Examples include barbituric acid.

These compounds are usually used in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the (A) ethylene copolymer. The ratio of these compounds to the ethylene-based copolymer depends on the vulcanization rate, processing stability, storage stability, mechanical properties of the vulcanizate,
It is selected as a preferable range from the viewpoint of compression set and the like. Below this range, the vulcanization rate becomes remarkably slow and the compression set deteriorates. On the other hand, it may be used in a ratio exceeding this range, but the effect cannot be expected to increase. It is preferably 0.1 to 10 parts by weight.

The ethylene-based elastomer vulcanizable composition according to the present invention is obtained by adding (A) an ethylene-based copolymer to these vulcanizing agents and reinforcing agents, fillers, plasticizers, stabilizers, processing agents usually used in the rubber industry. It is prepared by mixing the auxiliaries and the like with an ordinary kneader such as a roll or Banbury. The composition is molded into a shape suitable for the purpose, and is subjected to a vulcanization process to obtain a final product. The vulcanization temperature is usually 120 ° C
The above temperature is suitable, and it is preferably carried out at a temperature of about 150 ° C to 220 ° C for about 1 to 60 minutes. When post-vulcanization is performed, it is performed at a temperature of about 150 ° C to 200 ° C for about 1 to 24 hours.

The ethylene-based elastomer vulcanizable composition of the present invention has a fast vulcanization rate and excellent processing stability and storage stability against early vulcanization, and further has mechanical properties, heat aging resistance, and It is a new and efficient vulcanization system that gives vulcanizates excellent in terms of compression set. Conventionally, the vulcanization system used for an ethylene-based elastomer containing an epoxy group requires post-vulcanization for a relatively long time in order to obtain a good compression set. Since the vulcanization system can obtain a good compression set even when only press vulcanization is performed for a short time, post vulcanization can be omitted.

The vulcanized product of the ethylene-based elastomer composition obtained by the vulcanization system of the present invention has various properties such as heat aging resistance, weather resistance, water resistance, and compression set. In addition to various sealing materials (gaskets, O-rings, packing, oil seals), various hoses, diaphragms, etc., it can be effectively used widely for various belts and rolls.

<Examples> The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Examples 1 to 5 100 parts by weight of (A) ethylene copolymer shown in Table 1, 1 part of stearic acid, FEF carbon black (manufactured by Tokai Carbon Co., Ltd.,
Forty-five parts of the trade name Seast SO) and a predetermined amount of each vulcanizing material shown in Table 2 were kneaded with a 6-inch roll to prepare a compound.

The vulcanization rate of the obtained composition was measured with a Mooney scorch at 125 ° C. and an oscillating disc rheometer at 170 ° C., and then vulcanized using a steam press under the conditions shown in Table 3.

Vulcanized rubber physical properties and compression set were measured according to JIS-K-6301. For compression set, the deformation rate was measured after 72 hours at 25% compression and 150 ° C.

<Effects of the Invention> As described above, according to the present invention, an epoxy group-containing ethylene elastomer composition having excellent physical properties such as mechanical properties and compression set without post-vulcanization for a long time is provided. Can be provided.

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Claims (1)

[Claims] 1. (A) (a) 50 to 85 mol% of ethylene,
(B) 50 to 15 mol% of acrylic acid ester or methacrylic acid ester and (c) 1.0 to 8% by weight of unsaturated glycidyl ester based on the total of both components (a) and (b) are copolymerized. (B) a compound containing two or more carboxyl groups in the molecule and / or an anhydride of a polycarboxylic acid, and (C) a quaternary ammonium salt, relative to 100 parts by weight of the ethylene copolymer Alternatively, an ethylene elastomer composition comprising a quaternary phosphonium salt, (D) a urea derivative compound, and (E) a compound containing two or more imidodicarbonyl bonds in the molecule.