JP4957008B2 - Acrylic elastomer composition - Google Patents

Description

  The present invention relates to an acrylic elastomer composition. More specifically, the present invention relates to an acrylic elastomer composition using a polycarboxylic acid vulcanizing agent having excellent dispersibility.

Acrylic elastomer compositions containing a halogen-containing acrylic elastomer, a polyvalent carboxylic acid, a quaternary ammonium salt and an acid acceptor are already known. It has also been proposed to use a polyvalent carboxylic acid salt in the acrylic elastomer composition. However, since polyvalent carboxylic acids or salts thereof have a high melting point and low solubility in acrylic elastomers, acrylic elastomer compositions using these polyvalent carboxylic acids (salts) as vulcanizing agents are dispersible. There is a problem.
JP 50-132057 A Japanese Patent No. 3324502

The object of the present invention is to provide (A) a halogen-containing acrylic elastomer, (B) a polyvalent carboxylic acid- forming substance , (C) a quaternary onium salt, (D) an acid acceptor and (E) an acidic phosphate ester processing aid. In the acrylic elastomer composition to contain, it is providing the thing which improved the point of the dispersion | distribution defect seen in a roll kneading sheet or a secondary vulcanizate.

An object of the present invention is to decompose the acrylic elastomer composition having the above composition as a polyvalent carboxylic acid- forming substance as the component (B) at a vulcanization temperature, preferably 150 to 250 ° C. A reaction product of a polyvalent carboxylic acid, which is a polyvalent carboxylic acid ester capable of forming a polyvalent carboxylic acid, with an alkyl vinyl ether or alkyl vinyl thioether having an alkyl group having 1 to 18 carbon atoms, and more preferably with a basic substance This is achieved by using a mixture.

In the acrylic elastomer composition of the present invention, the polyvalent carboxylic acid used as a vulcanizing agent is esterified, and since there is no hydrogen bond between hydroxyl groups, there is no intermolecular force, and in many cases it is liquid, By introducing an alkyl group having an appropriate length, it can be dissolved in a solvent having a small polarity such as a hydrocarbon solvent. Furthermore, the presence of the ester group makes it easily soluble in solvents such as esters and ketones. In addition, since it has excellent compatibility with the acrylic elastomer itself, poor dispersion does not occur when an acrylic elastomer composition is obtained.

  This esterified polyvalent carboxylic acid is thermally decomposed at the vulcanization temperature, and becomes a free acid with good dispersibility and an alkyl vinyl ether or alkyl vinyl thioether. It does not leave, but generates an alkyl vinyl (thio) ether which is a gas, but since the generation is earlier in time than the vulcanization reaction, the secondary vulcanizate does not foam. For this reason, the problem of the dispersion | variation seen in the intensity | strength and elongation of a vulcanizate resulting from the poor dispersion | distribution seen by the prior art is also eliminated.

In kneading, it is necessary to use an acidic phosphate ester of a higher alcohol or an acidic phosphate ester of polyoxyethylene alkyl ether as a processing aid, which makes it possible to vulcanize such as in the case of stearic acid. There is no inhibition.

  The acrylic elastomer composition of the present invention having such characteristics is effectively used as a sealing material for oil seals, O-rings, packings, gaskets and the like, and as a vulcanization molding material for hoses and the like.

As the halogen-containing acrylic elastomer of component (A), at least one of alkyl acrylate, alkoxyalkyl acrylate, alkylthioalkyl acrylate, cyanoalkyl acrylate and the like is a main component (about 60 to 99.8% by weight), and (1) 2 -Chloroethyl vinyl ether, 2-chloroethyl acrylate, vinyl benzyl chloride (chloromethyl styrene), (2) vinyl chloroacetate, allyl chloroacetate, (3) glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc. (4) Alkenyl ester of α- or β-halogen-substituted aliphatic monocarboxylic acid, haloalkyl ester of (meth) acrylic acid, haloalkylalkenyl ester, haloalkyl A copolymer obtained by copolymerizing about 0.1 to 10% by weight, preferably about 1 to 5% by weight of a crosslinking site halogen-containing monomer such as a rualkenyl ketone or a haloacetoxyalkyl ester or a haloacetyl group-containing unsaturated compound is used. In this copolymer, other common vinyl compounds can be copolymerized within a range of about 30% by weight or less. Alternatively, an acrylic copolymer obtained by copolymerizing lactone-modified acrylate, terminal cyanolactone-modified acrylate, or the like can also be used.
JP 63-264612 A JP-A-1-123809

  Examples of the halogen-containing acrylic elastomer include halogen and carboxyl group-containing acrylic rubber, such as unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and maleic acid or mono-lower alkyl maleates in the halogen-containing acrylic elastomer. A copolymer obtained by copolymerizing a saturated dicarboxylic acid monoester in an amount of about 0.1 to 10% by weight, preferably about 1 to 5% by weight is also used.

Examples of the polyvalent carboxylic acid ester of the component (B), the vulcanization temperature, preferably decomposes at vulcanization temperature of 150 to 250 ° C., polyhydric is capable of forming a free polycarboxylic acid polycarboxylic acid ester A reaction product of a carboxylic acid and an alkyl vinyl ether or alkyl vinyl thioether having an alkyl group having 1 to 18 carbon atoms is used.

  As the polycarboxylic acid, an aliphatic, alicyclic or aromatic polycarboxylic acid having 4 to 30 carbon atoms, preferably an aliphatic dicarboxylic acid, is used, and the polycarboxylic acid is an acid anhydride. Also good.

  More specifically, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1, 12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, hexadecanedioic acid, β, β-dimethylsuccinic acid, β, β-dimethylglutaric acid, β-ethylglutaric acid, α-ethyladipic acid, trimethyladipic acid, n-hexyl succinic acid, n-octyl succinic acid, n-decyl succinic acid, n-decenyl succinic acid, n-tetradecyl succinic acid, n-octadecyl succinic acid, isooctadecenyl succinic acid, n-eicosenyl succinic acid , Saturated aliphatic dicarboxylic acids such as n-dodecenyl succinic acid, unsaturated aliphatic dicarboxylic acids such as maleic acid and fumaric acid, 1,2-cyclohexanedicarboxylic acid, 1,3- Examples thereof include alicyclic dicarboxylic acids such as chlorohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, preferably sebacic acid, adipic acid, 1,2 4-Benzenetricarboxylic acid is used.

  These polyvalent carboxylic acids are used after being reacted with an alkyl vinyl ether or alkyl vinyl thioether having an alkyl group having 1 to 18 carbon atoms, preferably 2 to 6 carbon atoms. The alkyl vinyl ether used is methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tertiary butyl vinyl ether, n-amyl vinyl ether, isoamyl vinyl ether, 2-ethylhexyl vinyl ether, n-octadecyl vinyl ether. In addition, as the alkyl vinyl thioether, thioethers corresponding to these are used, and isopropyl vinyl ether, butyl vinyl ether, ethyl vinyl thioether, butyl vinyl thioether, and the like are preferably used from the viewpoint of easy availability.

Polyvalent carboxylic acid esters obtained from these polyvalent carboxylic acids and alkyl vinyl (thio) ethers are represented by the following general formula.
R [COOCH (CH ₃ ) OR ′] n
R [COOCH (CH ₃ ) SR ′] n
R: Group derived from polyvalent carboxylic acid
R ′: group derived from alkyl group of alkyl vinyl (thio) ether
n: Polyvalent basic number of polyvalent carboxylic acid, preferably 2-4

It should be noted that by adding alkyl vinyl ether to halogen-containing acrylic rubber, it is possible to improve the compression set resistance without substantially impairing the normal properties and heat aging properties of the vulcanizate. As proposed by the applicant, in this case, only the Mooney viscosity (ML _{1 + 4} ) and scorch time are measured at the same time as unvulcanized properties, and the purpose is to eliminate poor dispersion. Absent.
JP-A-8-29579

  In the present invention, the polyvalent carboxylic acid ester is preferably a basic substance, for example, a mixture with an alkali metal compound such as potassium hydroxide, sodium hydroxide or sodium carbonate, more specifically, a base in the polyvalent carboxylic acid ester. A substance in which about 0.01 to 0.1% by weight of a residual substance is left is used. The purpose of leaving the basic substance is to improve the storage stability of the polyvalent carboxylic acid ester.

  Such a mixture is prepared by heating a polycarboxylic acid and an alkyl vinyl (thio) ether with an acidic substance such as an acidic phosphate ester as a catalyst at a reflux temperature for several hours in a solvent such as acetone. It can be obtained by neutralizing the catalyst and unreacted acid with a substance, washing with water, and drying with a predetermined amount of basic substance remaining.

  The polycarboxylic acid ester is used in a proportion of about 0.5 to 20 parts by weight, preferably about 1 to 10 parts by weight, per 100 parts by weight of the halogen-containing acrylic elastomer. If the ratio is less than this, the crosslinking is insufficient and the physical properties are impaired.

The quaternary onium salt of component (C) is represented by the following general formula, and preferably a quaternary phosphonium salt is used.
_{(R 1 R 2 R 3 R} 4 N) + X - or _{(R 1 R 2 R 3 R} 4 P) + X -
R _{1 to} R ₄ : an alkyl group having 1 to 25 carbon atoms, an alkoxyl group, an aryl group, an alkylaryl group, an aralkyl group or a polyoxyalkylene group, or 2 to 3 of these are a heterocyclic ring together with N or P A structure can also be formed.
^{X -: Cl -, Br -} , I -, HSO 4 -, H 2 PO 4 -, RCOO -, ROSO 2 -, CO 3 - , etc. A of
Nion

  Specifically, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium iodide, n-dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, trimethylbenzylammonium bromide , Cetyldimethylbenzylammonium chloride, cetylpyridium bromide, cetylpyridium sulfate, tetraethylammonium acetate, trimethylbenzylammonium benzoate, trimethylbenzylammonium borate, 5-benzyl-1,5-diazabicyclo [4,3,0] -5- Nonenium chloride, 5-benzyl-1,5-diazabi B Quaternary ammonium salts such as [4,3,0] -5-nonenium tetrafluoroborate, or tetraphenylphosphonium chloride, benzyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, triphenylmethoxymethylphosphonium chloride, triphenyl Quaternary phosphonium salts such as methylcarbonylmethylphosphonium chloride, triphenylethoxycarbonylmethylphosphonium chloride, trioctylbenzylphosphonium chloride, trioctylmethylphosphonium chloride, trioctylethylphosphonium acetate, tetraoctylphosphonium chloride, trioctylethylphosphonium dimethyl phosphate Used.

  These quaternary onium salts are used in a proportion of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the halogen-containing acrylic elastomer. If the ratio is less than this, the progress of vulcanization is remarkably slowed. On the other hand, if it is used at a ratio higher than this, the physical properties are impaired.

  As the acid acceptor of component (D), fatty acid salts or carbonates of alkali metals or alkaline earth metals are also used, but anion exchangers such as hydrotalcites are preferably used.

Hydrotalcites are represented by the general formula Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O, and are synthetic hydrotalcites such as surface treatment, surface untreated, decrystallized water, and firing, Russian Ural region. Natural minerals such as those produced in Norway and the Norwegian Snarum region can be used. Actually, commercially available products such as Kyowa Chemical products DHT-4A, DHT-4A-2, KW-2000 and the like can be used as they are.

These hydrotalcites are inorganic anion exchangers, and the CO ₃ portion in the structure is substituted with halogen ions or the like to inactivate halogen. For example, in the case of chlorine ions,
Mg _4.5 Al ₂ (OH) ₁₃ CO ₃・ 3.5H ₂ O + 2HCl
→ Mg _4.5 Al ₂ (OH) ₁₃ Cl ₂・ mH ₂ O + CO ₂
In general, the trapped chlorine does not desorb until it reaches about 450 ° C. or more, and is usually completely inactive. Commonly used metal oxides, such as MgO, produce MgCl ₂ after catching hydrochloric acid, which causes water resistance degradation and metal corrosion. Occurrence can be prevented.

  The acid acceptor such as hydrotalcite having such an action is used in a ratio of about 0.5 to 20 parts by weight, preferably about 1 to 10 parts by weight, per 100 parts by weight of the halogen-containing acrylic elastomer. If the ratio is less than this, vulcanization is inhibited and hardly proceeds. On the other hand, if it is used at a ratio higher than this, the physical characteristics are impaired.

In addition to the above essential components, other compounding agents such as fillers, lubricants, vulcanization retarders, plasticizers, anti-aging agents and the like are appropriately blended and used. In general, higher fatty acids such as stearic acid are used as a lubricant, but in the composition of the present invention, higher fatty acids inhibit cross-linking, so that the general formula (HO) _n PO [(OCH ₂ CH ₂ ) _m OR ] An acidic phosphate of a higher alcohol represented by _3-n (R: an alkyl group having 10 to 20 carbon atoms, n: 1 or 2, m: an integer of 0 to 5) or an acidic phosphoric acid of a polyoxyethylene alkyl ether Esters such as polyoxyethylene octadecyl ether phosphate are used as component (E) processing aids, and in fact, commercially available Toho Chemical product Phosphanol RL210 is used. The acidic phosphate ester of these higher alcohols or the acidic phosphate ester of polyoxyethylene alkyl ether is used at a ratio of about 0.1 to 10 parts by weight, preferably about 1 to 5 parts by weight per 100 parts by weight of the halogen-containing acrylic elastomer. . If the ratio is less than this, the anti-adhesion effect is not observed, while if the ratio is greater than this, the vulcanization rate is delayed.

  The composition is prepared by kneading using a kneader, Banbury mixer, open roll, or other mixer. Further, if necessary, oven vulcanization or steam vulcanization is performed as secondary vulcanization at about 150 to 200 ° C. for about 1 to 24 hours. The polyvalent carboxylic acid ester used as one component of the composition decomposes at this vulcanization temperature to form a free carboxylic acid that acts as a vulcanizing agent.

  Next, the present invention will be described with reference to examples.

Reference example 1
In a 500 ml four-necked flask equipped with a thermometer, reflux condenser and stirrer, 10.1 g (49.9 mmol) of sebacic acid, 15 g (150 mmol) of n-butyl vinyl ether, 50 g of acetone and dibutyl acid phosphate (the eighth chemical product) DP-4) 0.1 g was added and reacted at a liquid temperature of 60 ° C. for 16 hours. After the reaction solution was cooled to room temperature, 100 ml of a 0.5 mol / L KOH aqueous solution was added. The aqueous layer was discarded, 100 ml of toluene was added, 100 ml of KOH aqueous solution having the same concentration was further added, and the toluene layer was separated.

  The toluene layer was filtered with No. 2 paper, 0.1 ml of KOH aqueous solution with the same concentration was added, and toluene and water were distilled off with an evaporator. 19.70 g (yield 98.1%) of a compound having a structure in which 2 mol of butyl vinyl ether was added to sebacic acid (molecular weight 402.57; theoretical yield 20.088 g) was obtained. The appearance of this compound (mixture with KOH) was liquid, the acid value was 0, and there was no free acid.

When the thermal decomposition temperature was measured by TG / DTA measurement, the weight 1% reduction temperature was 170 ° C, the weight 5% reduction temperature was 188 ° C, and the 100% solution temperature was 225 ° C. This measurement was performed under an atmosphere of nitrogen gas at a temperature rising rate of 10 ° C./min. When 1 g of this product (mixture with KOH) was dissolved in 1 g of n-hexane, acetone, and butyl acetate, all were uniformly dissolved. In the infrared absorption spectrum (manufactured by JASCO Corporation FT / IR 480plus), not observed the absorption of carboxylic acid near 1700 cm ^-1 and 3300 cm ^-1, it was identified a ¹ HNMR in the following structure.
¹ HNMR (300MHz; JASCO JNM-LA300FTNMR)
a: 0.89-0.94ppm
b: 1.32 to 1.41 ppm
c: 1.32 to 1.41 ppm
d: 3.4 to 3.7 ppm
e: 5.9 to 6.0 ppm
f: 1.32 to 1.41 ppm
g: 2.29 to 2.31 ppm
h: 1.53 to 1.55 ppm
i: 1.32 to 1.41 ppm
C H ₃ C H ₂ C H ₂ C H ₂ OC H (C H ₃ ) OCOC H ₂ C H ₂ (C H ₂ ) ₄ C H ₂ C H ₂ COOC H (C H ₃ ) OC H ₂ C H ₂ C H ₂ C H ₃
A bcdefghihgefdcba

Reference example 2
Reference Example 1, the same number of moles of ethyl vinyl sulfide _{C 2 H 5 SCH = CH 2} 13.2g (0.15 mol) used in place of n- butyl vinyl ether, the following compounds (the mixture of KOH) 18.1 g (yield Rate 64.2%). The appearance of this compound was liquid, the acid value was 0, and the solubility was the same as in Reference Example 1.
C ₂ H ₅ SCH (CH ₃ ) OCOCH ₂ CH ₂ (CH ₂ ) ₄ CH ₂ CH ₂ COOCH (CH ₃ ) SC ₂ H ₅

Reference example 3
In Reference Example 1, the toluene layer was filtered with No. 2 paper, and instead of adding 0.1 ml of KOH aqueous solution of the same concentration, the toluene layer was washed 5 times with 100 ml of distilled water, and the washing solution was neutralized. The toluene layer was filtered with No. 2 paper, and then toluene and water were distilled off with an evaporator to obtain a compound having a structure in which 2 mol of butyl vinyl ether was added to sebacic acid. The solubility, infrared absorption spectrum and ¹ HNMR data of this compound were all the same as those in Reference Example 1.

Example 1
100 parts by weight of EA-BA-MEA-CMS (48 / 24.5 / 25 / 2.5% by weight) copolymer rubber
FEF carbon black 50 〃
4,4'-bis (α, α'-dimethylbenzyl) diphenylamine 2
(Ouchi Emerging Chemical Product Nocrack CD)
Processing aid (Toho Chemical Product Phosphanol RL210) 2 〃
Sebacic acid diester-KOH mixture obtained in Reference Example 2.1
Octadecyltrimethylammonium bromide 1 〃
Synthetic hydrotalcite (Kyowa Chemical Product DHT 4A-2) 2
Note) EA: Ethyl acrylate
BA: n-butyl acrylate
MEA: 2-methoxyethyl acrylate
CMS: p-chloromethylstyrene
VCA: Vinyl chloroacetate (Example 2)
After kneading each of the above components with an open roll, the kneaded product was press vulcanized at 180 ° C. for 10 minutes, and further oven vulcanized (secondary vulcanization) at 175 ° C. for 4 hours.

The following characteristics were observed and measured for the kneaded product, roll kneaded sheet and secondary vulcanization.
Kneadability: Visual observation of presence / absence of roll adhesion Visual observation of roll kneaded sheet: Microscopic observation of cross section of sheet at magnification of 100x, observation of presence / absence of poor dispersion Visual observation of secondary vulcanizate: Sheet at magnification of 100x Microscopic observation of the cross section to observe the presence or absence of poor dispersion and foaming. Vulcanized properties of secondary vulcanizate: JIS K6301 compliant Secondary vulcanized compression set: JIS K6301 compliant; 150 ° C, 70 hours , 25% compression

Example 2
In Example 1, the same amount of EA-BA-MEA-VCA (48/25/25/2 wt%) copolymer rubber was used as the acrylic elastomer.

Example 3
In Example 1, instead of the sebacic acid diester-KOH mixture obtained in Reference Example 1, the same amount of sebacic acid diester-KOH mixture obtained in Reference Example 2 was used.

Example 4
In Example 1, instead of the sebacic acid diester-KOH mixture obtained in Reference Example 1, the same amount of sebacic acid diester obtained in Reference Example 3 was used.

Comparative Example 1
In Example 1, instead of the sebacic acid diester-KOH mixture obtained in Reference Example 1, 1 g of sebacic acid having the same mole number was used.

Comparative Example 2
In Example 2, instead of the sebacic acid diester-KOH mixture obtained in Reference Example 1, 1 g of sebacic acid with the same mole number was used.

Comparative Example 3
In Example 1, no processing aid (phosphanol RL210) was used.

The results obtained in the above examples and comparative examples are shown in the following table.
table
Observation / Measurement items Real-1 Real-2 Real-3 Real-4 Ratio-1 Ratio-2 Ratio-3
Kneadability
Presence or absence of roll adhesion No No No No No No Yes Roll kneaded sheet appearance
Existence of poor distribution No No No No Yes Yes-
Secondary vulcanizate appearance
Existence of poor distribution No No No No Yes Yes-
No foaming None None None None None None −
Secondary vulcanizate properties
Hardness (JIS A) 69 70 69 69 69 70 −
100% modulus (MPa) 7.1 7.2 7.0 7.2 6.9 6.7 −
Strength at break (MPa) 13.0 14.8 13.5 13.0 12.8 14.5 −
Elongation at break (%) 220 170 240 220 240 180 −
Compression set (%) 12 11 12 11 12 11 −

Claims (6)

An acrylic elastomer composition containing (A) a halogen-containing acrylic elastomer, (B) a polyvalent carboxylic acid- forming substance , (C) a quaternary onium salt, (D) an acid acceptor and (E) an acidic phosphate ester processing aid in,
As the component (B) , a polyvalent carboxylic acid ester that can be decomposed at a vulcanization temperature to form a free polyvalent carboxylic acid and an alkyl vinyl ether or alkyl vinyl thioether having an alkyl group having 1 to 18 carbon atoms. An acrylic elastomer composition characterized by using a reaction product of The acrylic elastomer composition according to claim 1, wherein a polyvalent carboxylic acid ester capable of decomposing at a vulcanization temperature of 150 to 250 ° C to form a free polyvalent carboxylic acid is used as component (B) . The acrylic elastomer composition according to claim 1 or 2, wherein the polyvalent carboxylic acid ester is used as a mixture with a basic substance. The acrylic elastomer composition according to claim 3, wherein the basic substance is an alkali metal compound. The acrylic elastomer composition according to claim 3 or 4, wherein the mixture of the polyvalent carboxylic acid ester and the basic substance is obtained by leaving 0.01 to 0.1% by weight of the basic substance in the polyvalent carboxylic acid ester. The acidic phosphate ester processing aid used as component (E) has the general formula (HO) _n PO [(OCH ₂ CH ₂ ) _m OR] _3-n (Wherein R is an alkyl group having 10 to 20 carbon atoms, n is 1 or 2, and m is an integer of 0 to 5), an acidic phosphate ester or polyoxyethylene alkyl ether of a higher alcohol represented by 2. The acrylic elastomer composition according to claim 1, which is an acidic phosphate ester.