Phenothiazine derivative and acrylic rubber composition

Abstract

The present invention provides a phenothiazine derivative and a carboxyl-containing acrylic rubber composition, wherein the phenothiazine derivative is represented by the following general formula [I] (wherein, R 1 is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R 2 Ar is an aralkyl group, the R 2 The carboxyl-containing acrylic rubber composition contains, relative to 100 parts by weight of the carboxyl-containing acrylic rubber, (A) 0.1 to 5 parts by weight of a phenothiazine derivative represented by the general formula [I]; (B) 0.1 to 3 parts by weight of a crosslinking agent for the carboxyl-containing acrylic rubber; and (C) 0.1 to 5 parts by weight of a crosslinking accelerator for the carboxyl-containing acrylic rubber. #imgabs0#

Description

Technical Field

[0001] The present invention relates to a phenothiazine derivative and a carboxyl-containing acrylic rubber composition containing the phenothiazine derivative, and more particularly to a phenothiazine derivative capable of improving the heat resistance of acrylic rubber and a carboxyl-containing acrylic rubber composition containing the phenothiazine derivative. Background Art

[0002] As a countermeasure to global warming, environmental regulations, represented by CO2 emission control, are becoming increasingly stringent. As a countermeasure, automobile engines are required to have high output, high thermal efficiency, and reduced and harmless exhaust gas treatment, which has led to a trend of rising temperatures in the engine room. In line with this, rubber materials used around them are required to have further improved heat resistance.

[0003] As a specific example, vehicles equipped with a turbocharger system (for the purpose of improving engine fuel efficiency) are becoming more common. Since the air introduced from the turbocharger into the intercooler or the engine is high-temperature and high-pressure air, the rubber hose material that conveys this air is required to have high heat resistance.

[0004] As described above, as the use environment of rubber materials used in automobile engines becomes hotter or their life becomes longer, appropriate anti-aging agents are usually added to rubber product components to improve heat resistance.

[0005] Even in the case of acrylic rubber, a phenolic antioxidant or an amine antioxidant may be used as an antioxidant for the purpose of extending the life. Amine antioxidants include diphenylamine antioxidants, and a representative example thereof is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (Patent Documents 1 to 4).

[0006] In addition, in recent years, many patent documents describe that phenothiazine-based antioxidants are effective as antioxidants for rubber materials.

[0007] Patent Document 5 describes a rubber material which is excellent in vulcanization properties, mechanical properties and heat aging properties and is particularly suitable for anti-vibration rubber applications. The rubber material contains (A) a diene rubber, (B) a bismaleimide compound and (C) the following phenothiazine compound.

[0008]

[0009] R 1 , R 2 : Hydrogen atom; a C1-C8 alkyl or alkoxy group which may be substituted by an aromatic ring; a halogen atom; a cyano group.

[0010] R 3: A hydrogen atom, a C1-C6 chain or cyclic alkyl group, a vinyl group, or an aromatic group.

[0011] m, n: 0~2.

[0012] However, for the above compounds R 3 In the case of groups other than hydrogen atoms, the effect is not confirmed by specific examples. 1 and R 2 Furthermore, there is no mention of the case where the oxidation state of the sulfur atom at the 5-position is a sulfoxide group or a sulfone group.

[0013] Furthermore, phenothiazine compounds in which the sulfur atom at the 5-position is -SO2- are also known, and are described, for example, in Patent Document 6. The document describes a fused heterocyclic compound represented by the following general formula and an organic material composition containing the fused heterocyclic compound, and it is described that the organic material composition can impart high processing stability, heat resistance, and long life to organic materials such as polymers that are susceptible to oxidation, heat, or photoinduced breakdown.

[0014]

[0015] Y: chemical single bond, -S(=O)-, -SO2-.

[0016] R a , R b :C1~C 30 Organic group.

[0017] Z a , Z b : Chemical single bond, -SO2-.

[0018] X 1 , X 2 :Hydrogen atom, halogen atom, alkyl group, cyano group, nitro group, -OR 1 、-O-CO-R 1 、-CO-OR 1 、-O-CO-OR 1 、-NR 2 R 3 、-NR 2 -CO-R 1 、-CO-NR 2 R 3 、-O-CO-NR 2 R 3 .

[0019] n, m: 0 to 2, either of which is not 0.

[0020] However, there is no specific description of an example in which the hydrogen atom on the amino group at position 10 is replaced by a hydrocarbon group. Furthermore, although the compound shown below (hereinafter referred to as CD-SO2) is cited as a specific example of the above general formula, since the compatibility of this compound with the acrylic elastomer is poor, poor dispersion occurs when forming a crosslinkable composition using an open roll or the like.

[0021]

[0022] Prior art literature

[0023] Patent Literature

[0024] Patent Document 1: Japanese Patent Application Laid-Open No. 11-21411

[0025] Patent Document 2: WO 2011 / 58918 A1

[0026] Patent Document 3: Japanese Patent Application Publication No. 2010-254579

[0027] Patent Document 4: WO 2006 / 001299 A1

[0028] Patent Document 5: Japanese Patent Application Publication No. 2015-227402

[0029] Patent Document 6: WO 2011 / 093443 A1

[0030] Patent Document 7: WO 2009 / 096545 A1 Summary of the invention

[0031] Problems to be solved by the invention

[0032] Although phenothiazine compounds represented by CD-SO2 can improve the heat resistance of acrylic rubber materials, there are problems in terms of dispersibility in acrylic rubber, and it is desired to improve their dispersibility. The object of the present invention is to provide a novel compound with anti-aging effect and an acrylic rubber composition containing the compound, wherein the compound can improve the heat resistance of acrylic rubber and has excellent dispersibility in acrylic rubber.

[0033] Technical means to solve problems

[0034] The above-mentioned first object of the present invention can be achieved by a phenothiazine derivative represented by the following general formula [I].

[0035]

[0036] (Where R 1is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R 2 Ar is an aralkyl group, the R 2 Ar is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and Ar is a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0037] In addition, the second object of the present invention can be achieved by the following carboxyl-containing acrylic rubber composition, wherein the carboxyl-containing acrylic rubber composition contains, relative to 100 parts by weight of the carboxyl-containing acrylic rubber:

[0038] (A) 0.1 to 5 parts by weight of a phenothiazine derivative represented by formula [I];

[0039] (B) 0.1 to 3 parts by weight of a crosslinking agent for carboxyl-containing acrylic rubber;

[0040] (C) 0.1 to 5 parts by weight of a cross-linking accelerator for carboxyl-containing acrylic rubber.

[0041] Effects of the Invention

[0042] According to the present invention, a phenothiazine derivative and a carboxyl-containing acrylic rubber containing the phenothiazine derivative are provided, wherein the phenothiazine derivative can improve the heat resistance of the carboxyl-containing acrylic rubber and has excellent dispersibility in the acrylic rubber. In addition, compared with the conventional diphenylamine-based antioxidant, the phenothiazine derivative can also suppress the decrease in elongation at break of the acrylic rubber crosslinked product under a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a graph showing the change rate of the breaking strength of the acrylic rubber cross-linked product (solid line: Example 3, dotted line: Example 4, dashed line: Comparative Example 1, dotted line: Comparative Example 2).

[0044] Figure 2 It is a graph showing the change rate of elongation at break of the acrylic rubber cross-linked product (solid line: Example 3, dotted line: Example 4, dashed line: Comparative Example 1, dotted line: Comparative Example 2). DETAILED DESCRIPTION

[0045] In the phenothiazine derivative represented by the general formula [I], R 1It is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms. Specifically, it includes: a primary hydrocarbon group such as methyl, ethyl, n-propyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-undecyl, n-pentadecyl, and n-heptadecyl; a secondary hydrocarbon group such as isopropyl, 2-butyl, 2-pentyl, 3-pentyl, 2-hexyl, 3-hexyl, 2-heptyl, 3-heptyl, 4-heptyl, 2-octyl, 3-octyl, and 4-octyl; a tert-butyl, 1,1 - tertiary hydrocarbon groups such as dimethyl-1-propyl, 1,1-dimethyl-1-butyl, 1,1-dimethyl-1-pentyl, 1,1-dimethyl-1-hexyl, 3-methyl-3-pentyl, 3-ethyl-3-pentyl, 3-methyl-3-hexyl; alicyclic hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, 1-methyl-1-cyclopentyl, 1-methyl-1-cyclohexyl; 1-adamantyl, benzyl, 2-phenylethyl, etc.

[0046] In the case of R of the general formula [I] 2 In the aralkyl group represented by Ar, the R 2 R is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and specific examples thereof include methylene, ethylidene, 1-propylidene, 2-propylidene, and 1-butylidene. Ar is a monovalent aromatic hydrocarbon group having 1 to 10 carbon atoms, and specific examples thereof include phenyl and naphthyl. 2 Ar is preferably α,α-dimethylbenzyl.

[0047] The above-mentioned compound, especially the compound in which the aralkyl group is an α,α-dimethylbenzyl group, can be easily produced by the following method (Method A): after producing the following compound (hereinafter referred to as CD-S) by the method described in Patent Document 6, N-alkylating the NH group at position 10, and then oxidizing the sulfur atom at position 5 using an oxidizing agent such as hydrogen peroxide / acetic acid. Alternatively, a method in which the order of the N-alkylation reaction and the oxidation reaction is reversed can be used (Method B).

[0048]

[0049] Method A will be described in detail.

[0050] As the alkylating agent, there can be used 1 -X (X is a chlorine atom, a bromine atom or an iodine atom). The amount of the alkylating agent used is in the range of about 1 mol to 2 mol relative to 1 mol of the compound CD-S.

[0051] In the reaction, it is preferred to react CD-S with a base such as sodium hydride or potassium tert-butoxide, and then react it with an alkylating agent. The amount of the base used is in the range of about 1 to 2 mol relative to 1 mol of the compound CD-S.

[0052] As the reaction solvent, N,N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide or the like can be used.

[0053] The reaction of CD-S with the base is carried out at about 0°C to 10°C, and the reaction with the alkylating agent is carried out at 0°C to 100°C.

[0054] As the oxidizing agent used in the oxidation reaction, m-chloroperbenzoic acid, peracetic acid, or acetic acid / hydrogen peroxide can be used. The oxidizing agent is used in an amount of about 2 to 10 mol per mol of the alkylated CD-S.

[0055] As the reaction solvent, aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane and octane, chlorine-containing hydrocarbon solvents such as dichloromethane and chlorobenzene, acetic acid, etc. can be used alone or in combination of two or more.

[0056] The reaction is carried out at a temperature ranging from about 50°C to 150°C, preferably from about 80°C to 120°C.

[0057] Next, the acrylic rubber composition containing the phenothiazine derivative compound [I] of the present invention will be described.

[0058] The carboxyl group-containing acrylic rubber composition can be formed by blending the phenothiazine derivative [I], a crosslinking agent for carboxyl group-containing acrylic rubber, and a crosslinking accelerator for carboxyl group-containing acrylic rubber into a carboxyl group-containing acrylic rubber.

[0059] The phenothiazine derivative [I] of the present invention is used in an amount of about 0.1 to 5 parts by weight relative to 100 parts by weight of the carboxyl group-containing acrylic rubber. If the phenothiazine derivative [I] is less than 0.1 parts by weight, sufficient heat resistance and compression set resistance cannot be imparted to the cross-linked acrylic rubber. In addition, even if the amount of the phenothiazine derivative [I] used is more than 5 parts by weight, the heat resistance and compression set resistance of the cross-linked acrylic rubber cannot be improved, and it is not economical.

[0060] Examples of the acrylic rubber include carboxyl group-containing acrylic rubber, epoxy group-containing acrylic rubber, and active chlorine group-containing acrylic rubber, and carboxyl group-containing acrylic rubber is particularly preferred.

[0061] Specific examples of generally available acrylic rubbers include NipolAR series manufactured by Nippon Zeon, Denka ER series manufactured by Denki Kagaku Kogyo, Noxtite series manufactured by NOK, and Vamac series manufactured by DuPont.

[0062] The carboxyl group-containing acrylic rubber is prepared by copolymerizing at least one of an alkyl acrylate and an alkoxyalkyl acrylate with a carboxyl group-containing unsaturated compound as a copolymer component.

[0063] As the alkyl acrylate, an alkyl acrylate having an alkyl group with 1 to 8 carbon atoms can be used. For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-cyanoethyl acrylate, etc. can be used, and ethyl acrylate and n-butyl acrylate are preferably used.

[0064] As the alkoxyalkyl acrylate, an alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms can be used. For example, methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-n-butoxyethyl acrylate and the like can be used, and 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are preferably used.

[0065] These alkyl acrylates or alkoxyalkyl acrylates are usually used in the copolymerization reaction at a ratio of about 60% to 99.9% by weight, preferably about 80% to 99% by weight in the monomer mixture. When the polymerization reaction rate of the copolymerization reaction is 90% or more, the monomer mixing ratio is approximately the copolymerization ratio.

[0066] Alkoxyalkyl acrylate and alkyl acrylate may be used alone, respectively. Preferably, the former is used at a ratio of about 60% to 0% by weight and the latter is used at a ratio of about 40% to 100% by weight. When the alkoxyalkyl acrylate is copolymerized, the balance between oil resistance and cold resistance becomes good. However, when the alkoxyalkyl acrylate is copolymerized at a ratio exceeding 60% by weight, normal physical properties and heat resistance tend to decrease.

[0067] As the unsaturated compound containing a carboxyl group, for example, unsaturated monoacid compounds such as acrylic acid and methacrylic acid; unsaturated diacid compounds such as maleic acid, fumaric acid, itaconic acid, and citraconic acid; and unsaturated diacid monoesters such as monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monomethyl fumarate, monoethyl fumarate, and mono-n-butyl fumarate. Preferably, mono-n-butyl maleate and mono-n-butyl fumarate are used.

[0068] These carboxyl group-containing unsaturated compounds are used in a proportion of about 0.1 to 10% by weight, preferably about 1 to 5% by weight, in the monomer mixture.

[0069] In addition to the above components, an ethylenically unsaturated compound copolymerizable with the above-mentioned acrylic acid ester may be copolymerized in a ratio of about 20% by weight or less, preferably about 10% by weight or less. For example, examples of the ethylenically unsaturated compound include alkyl methacrylates, alkoxyalkyl methacrylates, styrene, α-methylstyrene, 4-methylstyrene, acrylamide, vinyl acetate, cyclohexyl acrylate, benzyl acrylate, vinyl chloride, vinylidene chloride, acrylonitrile, ethyl vinyl ether, butyl vinyl ether, ethylene, propylene, butadiene, isoprene, chloroprene, etc., other than the above-mentioned compounds.

[0070] As the crosslinking agent of the carboxyl-containing acrylic rubber, a polyamine compound or a derivative thereof can be used, specifically, an aliphatic polyamine compound, a carbonate of an aliphatic polyamine compound, an aliphatic polyamine compound in which the amino group is protected by an organic group, or an aromatic polyamine compound can be used.

[0071] For example, as an aliphatic polyamine compound, hexamethylenediamine can be cited. In addition, as a carbonate of an aliphatic polyamine compound, hexamethylenediamine carbamate can be cited. As an aliphatic polyamine in which the amino group is protected by an organic group, N,N'-dicinnamylidene-1,6-hexanediamine or a compound disclosed in Patent Document 7 can be cited.

[0072] Examples of the aromatic polyamine compound include 4,4'-methylenedianiline, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, m-phenylenediamine, p-phenylenediamine, 1,3,5-phenylenetriamine, 4,4'-(m-phenylenediisopropylidene)diphenylamine, 4,4'-(p-phenylenediisopropylidene)diphenylamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-diaminobenzanilide.

[0073] The polyamine compounds listed above may be used alone or in combination of two or more. Among them, hexamethylenediamine carbamate, 4,4'-diaminodiphenyl ether, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane are preferred.

[0074] The crosslinking agent is used in an amount of about 0.1 to 3 parts by weight relative to 100 parts by weight of the acrylic rubber. If the amount of the crosslinking agent is less than 0.1 parts by weight, crosslinking becomes insufficient, resulting in reduced mechanical properties and reduced crosslinking speed of the crosslinked product. If the amount of the crosslinking agent is more than 3 parts by weight, crosslinking is excessively performed, sometimes resulting in reduced elasticity and poor compression set resistance of the crosslinked product.

[0075] As the crosslinking accelerator of the carboxyl group-containing acrylic rubber, a guanidine compound, a diazabicycloolefin compound or an organic acid salt thereof, or an aliphatic monotertiary amine compound can be used.

[0076] Examples of the guanidine compound include tetramethylguanidine, tetraethylguanidine, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, etc. Preferably, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, or a combination thereof is used.

[0077] The diazabicycloolefin compound is preferably 1,8-diazabicyclo[5.4.0]-7-undecene or an organic acid salt thereof. Examples of the organic acid used for the organic acid salt of 1,8-diazabicyclo[5.4.0]-7-undecene include monobasic organic acids and dibasic organic acids.

[0078] Examples of the monobasic organic acid include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-decanoic acid, n-lauric acid, p-toluenesulfonic acid, and phenol. Examples of the dibasic organic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, phthalic acid, and phthalic acid. Preferred are monocarboxylic acids or dicarboxylic acids having 6 to 18 carbon atoms.

[0079] Examples of the aliphatic monotertiary amine compound include tri-n-octylamine, tri-2-ethylhexylamine, tri-n-decylamine, tri-n-dodecylamine, tri-n-tetradecylamine, tri-n-hexadecylamine, tri-n-octadecylamine, N,N-dimethyldecylamine, N,N-dimethylundecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N-dimethylhexadecylamine, and N,N-dimethyloctadecylamine. Particularly preferred are N,N-dimethyldecylamine, N,N-dimethylundecylamine, N,N-dimethyldodecylamine, N,N-dimethyltetradecylamine, N,N-dimethylhexadecylamine, and N,N-dimethyloctadecylamine.

[0080] The crosslinking accelerator is used in an amount of about 0.1 to 5 parts by weight, preferably about 0.3 to 3 parts by weight, relative to 100 parts by weight of the acrylic rubber. If the crosslinking accelerator is less than 0.1 parts by weight, the crosslinking speed may be significantly reduced, the mechanical properties of the acrylic rubber after crosslinking may be reduced, and the mechanical properties after heat aging may be reduced. On the other hand, if the amount of the crosslinking accelerator is more than 5 parts by weight, the compression set resistance of the acrylic rubber may be deteriorated.

[0081] In the carboxyl group-containing acrylic rubber composition, various additives such as fillers, processing aids, plasticizers, softeners, colorants, stabilizers, adhesion aids, mold release agents, conductivity-imparting agents, thermal conductivity-imparting agents, surface non-adhesives, tackifiers, flexibility-imparting agents, heat resistance improvers, flame retardants, ultraviolet absorbers, oil resistance improvers, scorch retardants, lubricants, etc. can be formulated as needed.

[0082] The filler includes: silica such as alkaline silica and acidic silica; metal oxides such as zinc oxide, calcium oxide, titanium oxide, and aluminum oxide; metal hydroxides such as magnesium hydroxide, aluminum hydroxide, and calcium hydroxide; carbonates such as magnesium carbonate, aluminum carbonate, calcium carbonate, and barium carbonate; silicates such as magnesium silicate, calcium silicate, sodium silicate, and aluminum silicate; sulfates such as aluminum sulfate, calcium sulfate, and barium sulfate; metal sulfides such as molybdenum disulfide, iron sulfide, and copper sulfide; synthetic hydrotalcite, diatomaceous earth, asbestos, lithopone (zinc sulfide / barium sulfide), graphite, carbon black (MT carbon black, SRF carbon black, FEF carbon black, etc.), carbon fluoride, calcium fluoride, coke, quartz fine powder, zinc white, talc, mica powder, wollastonite, carbon fiber, aramid fiber, various whiskers, glass fiber, organic reinforcing agent, organic filler, etc.

[0083] As processing aids, there can be mentioned: higher fatty acids such as stearic acid, oleic acid, palmitic acid, and lauric acid; higher fatty acid salts such as sodium stearate and zinc stearate; higher fatty acid amides such as stearamide and oleamide; higher fatty acid esters such as ethyl oleate; higher aliphatic amines such as stearylamine and oleylamine; petroleum waxes such as carnauba wax and ozokerite; polyethylene glycols such as ethylene glycol, glycerol, and diethylene glycol; aliphatic hydrocarbons such as vaseline and paraffin; silicone oils, silicone polymers, low molecular weight polyethylene, phthalates, phosphates, rosin, (halogenated) dialkylamines, (halogenated) dialkyl sulfones, surfactants, etc.

[0084] Examples of plasticizers include epoxy resins, phthalic acid derivatives, and sebacic acid derivatives; examples of softeners include lubricating oils, process oils, coal tar, castor oil, and calcium stearate; and examples of antioxidants include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

[0085] The carboxyl group-containing acrylic rubber composition can be prepared by mixing the phenothiazine derivative [I], a crosslinking agent, a crosslinking accelerator, and other compounding agents used as required with the above-mentioned carboxyl group-containing acrylic rubber, and mixing them using a Banbury mixer, a pressure kneader, an open roll, etc. The carboxyl group-containing acrylic rubber composition is crosslinked by performing a primary crosslinking at about 120° C. to 250° C. for about 1 minute to 60 minutes and an oven crosslinking (secondary crosslinking) at about 120° C. to 200° C. for about 1 hour to 20 hours as required.

[0086] Example

[0087] Hereinafter, the present invention will be described with reference to examples.

[0088] Reference Example 1

[0089] Production of 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine [CD-S]

[0090] In a 1000 ml four-necked flask equipped with a magnetic stirrer, a thermometer, a nitrogen inlet and outlet, and a reflux condenser, 59.8 g (0.3 mol) of phenothiazine, 1.44 g of p-toluenesulfonic acid, and 280 ml of toluene were placed, the temperature was raised to 80°C, 70.9 g (0.6 mol) of α-methylstyrene was added, and the mixture was reacted for 1 hour under a nitrogen atmosphere.

[0091] After the reaction mixture was cooled to room temperature, toluene was distilled off under reduced pressure to obtain 132 g of a purple solid reaction product. This was recrystallized from 600 ml to 800 ml of ethanol to obtain 90 g of crude CD-S in the form of light reddish purple crystals (yield: 69%). Furthermore, 20 g of the crude CD-S was recrystallized again from ethanol to obtain 18 g of refined CD-S in the form of colorless flaky crystals.

[0092]

[0093] Reference Example 2

[0094] Production of 3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2]

[0095] In a 500 ml four-necked flask equipped with a magnetic stirrer, a thermometer, a nitrogen inlet and outlet, and a reflux condenser, 24.9 g (0.125 mol) of phenothiazine, 0.6 g of p-toluenesulfonic acid, and 115 ml of toluene were placed, the temperature was raised to 80°C, 29.5 g (0.25 mol) of α-methylstyrene was added, and the mixture was reacted for 1 hour under a nitrogen atmosphere.

[0096] Next, 30 g of acetic acid was added to the reaction mixture, and then 42.5 g of 30% hydrogen peroxide was added in 5 portions, and the mixture was further reacted at 80° C. for 2 hours. The contents were cooled to room temperature and allowed to stand, and then the upper toluene layer was injected into 500 ml of methanol. After standing at room temperature overnight, 42.5 g of crude CD-SO2 was obtained as pale yellow crystals (yield 72%). It was recrystallized from ethanol to obtain 38 g of CD-SO2 as pale yellow needle crystals (yield 65%).

[0097]

[0098] Example 1

[0099] Production of 10-benzyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2-Bn]

[0100] In a 300 ml four-necked flask equipped with a magnetic stirrer, a thermometer, a gas inlet and outlet, and a reflux condenser, 21.8 g (50 mmol) of purified CD-S and 160 ml of N,N-dimethylformamide were added and cooled to below 5°C under a nitrogen atmosphere. While keeping the temperature in the system below 10°C, 1.8 g (75 mmol) of sodium hydride was added and reacted for 1 hour. After adding 9.5 g (75 mmol) of benzyl chloride, it was reacted at 70°C for 1 hour. After the obtained reaction mixture was cooled to room temperature, it was injected into a saturated sodium chloride aqueous solution. The product was extracted with dichloromethane, and the organic layer was dried with anhydrous magnesium sulfate. After filtering out the magnesium sulfate, the volatile components were removed from the filtrate under reduced pressure to obtain 27.2 g of crude CD-S-Bn as a light yellow solid.

[0101]

[0102] 26.3 g of crude CD-S-Bn was dissolved in 300 ml of toluene and placed in a 500 ml three-necked flask equipped with a magnetic stirrer, a thermometer and a reflux condenser. Then, 30 g of acetic acid and 34 g of 30% hydrogen peroxide were added in sequence and reacted at 90° C. for 2 hours.

[0103] After the contents were cooled to room temperature, the upper toluene layer was taken out and volatile substances were distilled off under reduced pressure. The obtained pale yellow solid was recrystallized from toluene to obtain 19.5 g of CD-SO2-Bn as colorless crystals (yield based on CD-S was 70%).

[0104] 1 H NMR (400 MHz, acetone d6, δ ppm):

[0105] 1.74(s, 12H, -C(C H 3)2-)

[0106] 5.56(s, 2H, NC H 2-Ar)

[0107] 7.15~7.45(m、19H、Ar)

[0108] 7.93 (d, J = 2.4 Hz, 2H, Ar)

[0109]

[0110] Example 2

[0111] Production of 10-n-propyl-3,7-bis(α,α-dimethylbenzyl)-10H-phenothiazine-5,5-dioxide [CD-SO2-Pr]

[0112] In a 300 ml four-necked flask equipped with a magnetic stirrer, a thermometer, a gas inlet and outlet, and a reflux condenser, 21.8 g (50 mmol) of purified CD-S and 160 ml of N,N-dimethylformamide were added and cooled to below 5°C under a nitrogen atmosphere. While keeping the temperature in the system below 10°C, 1.8 g (75 mmol) of sodium hydride was added and reacted for 1 hour. After adding 8.0 g (65 mmol) of n-propyl bromide, it was reacted at 70°C for 1 hour. After the obtained reaction mixture was cooled to room temperature, it was injected into a saturated sodium chloride aqueous solution. The product was extracted with ethyl acetate, and the organic layer was dried with anhydrous magnesium sulfate. After filtering out magnesium sulfate, the volatile components were removed from the filtrate under reduced pressure to obtain 24.9 g of crude CD-S-Pr as a light yellow solid.

[0113]

[0114] 24.9 g of crude CD-S-Pr was dissolved in 250 ml of toluene and placed in a 500 ml three-necked flask equipped with a magnetic stirrer, a thermometer and a reflux condenser. Then, 40 g of acetic acid and 34 g of 30% hydrogen peroxide were added in sequence and reacted at 90° C. for 2 hours.

[0115] After the contents were cooled to room temperature, the upper toluene layer was taken out and the volatile substances were distilled off under reduced pressure. The resulting red high-viscosity liquid was recrystallized with toluene / ethanol (5 / 1 (v / v)) to obtain 21.7 g of CD-SO2-Pr as colorless crystals (the yield based on CD-S was 85%).

[0116] 1 H NMR (400MHz, CDCl3, δppm):

[0117] 1.01(t,J=7.2Hz,3H,-CH2CH2C H 3)

[0118] 1.73(s,12H,-C(C H 3)2-)

[0119] 1.89(sectet,J=7.6Hz,2H,-CH2C H 2CH3)

[0120] 4.03(t,J=8.0Hz,2H,-C H2CH2CH3)

[0121] 7.14-7.32 (m, 14H, Ar)

[0122] 8.13 (d, J = 2.4 Hz, 2H, Ar)

[0123]

[0124] Example 3

[0125] Carboxyl-containing acrylic rubber (Unimatec product Noxtite PA-521, Tg: -21°C)

[0126]

[0127] The carboxyl-containing acrylic rubber, FEF carbon black, stearic acid and polyoxyethylene stearyl ether phosphate in the above components are mixed by a Banbury mixer. The remaining components in the obtained mixture are mixed in a predetermined amount by an open roller to obtain an acrylic rubber composition. The composition is subjected to primary crosslinking at 180°C for 8 minutes and oven crosslinking at 175°C for 4 hours by a 100-ton press molding machine to obtain a sheet-like crosslinked product with a thickness of about 2 mm and a cylindrical crosslinked product with a diameter of about 29 mm and a height of about 12.5 mm.

[0128] Furthermore, the surface of the acrylic rubber composition obtained by mixing with an open roll was visually observed to check for the presence of minute white spots caused by the antioxidant.

[0129] The crosslinking characteristics of the acrylic rubber composition and the physical properties of its crosslinked product were measured as follows.

[0130] Mooney scorch test: In accordance with JIS K6300-1 (125°C) corresponding to ISO 289-1

[0131] The minimum Mooney viscosity (ML) was measured using a Mooney viscometer AM-3 manufactured by Toyo Seiki Seisaku-sho. min ) and scorch time (t5)

[0132] Cross-linking test: In accordance with JIS K6300-2 corresponding to ISO 6502 (180°C, 12 minutes)

[0133] The values ​​of ML, MH, tc(10) and tc(90) were measured using a rotorless rheometer RLR-3 manufactured by Toyo Seiki Seisaku-sho.

[0134] ML: Minimum torque

[0135] MH: Maximum torque

[0136] tc(10): time required for the cross-linking torque to reach ML+(MH-ML)×0.1

[0137] tc(90): Time required for the cross-linking torque to reach ML+(MH-ML)×0.9 Normal physical properties: Based on JIS K6251 corresponding to ISO37, JIS K6253 corresponding to ISO 37 Air heating aging test: Based on JIS K6257 corresponding to ISO 188

[0138] (190°C: 70 hours, 250 hours, 375 hours, 500 hours)

[0139] Compression set: In accordance with JIS K6262 corresponding to ISO 815-1

[0140] (175°C: 70 hours, 500 hours)

[0141] Example 4

[0142] In Example 3, the same amount (2 parts by weight) of CD-SO2-Pr was used instead of CD-SO2-Bn.

[0143] Comparative Example 1

[0144] In Example 3, the same amount (2 parts by weight) of 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (Nocrac CD, a product of Ouchi Shinko Chemical Industry Co., Ltd.) was used instead of CD-SO 2 —Bn.

[0145] Comparative Example 2

[0146] In Example 3, the same amount (2 parts by weight) of CD-SO2 was used instead of CD-SO2-Bn.

[0147] The results obtained in Examples 3 and 4 and Comparative Examples 1 and 2 are shown in the following table.

[0148] surface

[0149]

[0150] Regarding the dispersibility of the antioxidant in the uncrosslinked acrylic rubber composition, CD-SO2-Bn used in Example 3 and CD-SO2-Pr used in Example 4 are superior to CD-SO2 used in Comparative Example 2 and are at the same level as Nocrac CD used in Comparative Example 1. In the heat aging test, the reduction rate of elongation at break in Examples 3 and 4 was suppressed to be lower than that in Comparative Example 1. It should be noted that Figure 1 In the figure, the breaking strength change rates of Example 3 and Comparative Example 2 overlap in the test time of 250 hours to 500 hours.

Claims

1. A phenothiazine derivative represented by the following general formula [I]: In the formula, R 1 is benzyl or n-propyl, R 2 Ar is α,α-dimethylbenzyl.

2. The phenothiazine derivative according to claim 1, wherein The phenothiazine derivative is used as a compounding agent for carboxyl-containing acrylic rubber.

3. A carboxyl-containing acrylic rubber composition, wherein: Relative to 100 parts by weight of carboxyl-containing acrylic rubber, it contains: (A) 0.1 to 5 parts by weight of a phenothiazine derivative represented by the following general formula [I], In the formula, R 1 is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R 2 Ar is an aralkyl group, the R 2 is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, and Ar is a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms; (B) 0.1 to 3 parts by weight of a crosslinking agent for carboxyl-containing acrylic rubber; (C) 0.1 to 5 parts by weight of a cross-linking accelerator for carboxyl-containing acrylic rubber.

4. The carboxyl-containing acrylic rubber composition according to claim 3, wherein The carboxyl-containing acrylic rubber crosslinking agent is a polyamine compound or a derivative thereof, wherein the derivative is a carbonate of an aliphatic polyamine compound or an aliphatic polyamine compound in which the amino group is protected by an organic group.

5. The carboxyl-containing acrylic rubber composition according to claim 4, wherein The polyamine compound or its derivative is hexamethylenediamine, hexamethylenediamine carbamate, 4,4'-diaminodiphenyl ether or 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

6. The carboxyl-containing acrylic rubber composition according to claim 3, wherein The cross-linking accelerator for the carboxyl-containing acrylic rubber is a guanidine compound, a diazabicycloolefin compound or an organic acid salt thereof, or an aliphatic monotertiary amine compound.

7. The carboxyl-containing acrylic rubber composition according to claim 6, wherein The guanidine compound is 1,3-diphenylguanidine or 1,3-di-o-tolylguanidine.

8. The carboxyl-containing acrylic rubber composition according to claim 6, wherein The diazabicycloolefin compound or its organic acid salt is 1,8-diazabicyclo[5.4.0]-7-undecene or its organic acid salt.

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