CN107922718B - Polybutylene terephthalate resin composition - Google Patents

Abstract

Provide: Polybutylene terephthalate resin with excellent physical and chemical properties, etc., and molded articles suitable for use in contact with high-temperature automotive lubricants such as ATF, and excellent ATF resistance resin composition. The polybutylene terephthalate resin composition of the present invention is used to constitute a molded article used in contact with lubricating oil for automobiles, and the composition contains a polybutylene terephthalate resin and carbodiimide A compound wherein the tensile strength retention rate of the molded article after being immersed in a lubricating oil for automobiles at 150° C. for 250 hours is 50% or more.

Description

Polybutylene terephthalate resin composition

technical field

The present invention relates to a polybutylene terephthalate resin composition, and more specifically, to a polybutylene terephthalate resin constituting a molded article used in contact with an automotive lubricating oil such as ATF combination.

Background technique

For example, there is an AT connector as a component for connecting electronic components that control a transmission mechanism of an automobile (AT vehicle). This AT connector is usually used in a state of being immersed in ATF (automatic transmission fluid), which is a type of lubricating oil.

ATF is heated to a very high temperature of, for example, about 150°C, exceeding 100°C. As a molded product such as an AT connector used in the state of being immersed in the ATF, it will have excellent heat resistance, hydrolysis resistance, etc. regarded as a condition. In addition, it is not limited to ATF, and other lubricating oils for automobiles, such as engine oil, brake oil, gear oil, etc., are also kept in a very high temperature state. Molded products are exposed to harsh environments in terms of heat resistance and hydrolysis resistance.

Therefore, conventionally, as a molded article provided in contact with automotive lubricating oil such as ATF, it is composed of PPS (polyphenylene sulfide resin), polyamide resin, or the like (for example, refer to Patent Document 1).

However, for automotive lubricating oils such as ATF, research to improve performance has also been carried out, and products with higher temperature and various additives are developed to improve performance, and molded products used in contact with ATF and the like In this case, even more excellent performance is required.

Among them, so-called ATF resistance, which does not cause decomposition of the components constituting the molded article and does not cause a reduction in strength, is required even if it is in contact with high-temperature automotive lubricating oil such as ATF for a long time. It should be noted that the ATF resistance will be described in detail later.

However, polybutylene terephthalate resins are excellent in mechanical properties, other physical properties, and chemical properties, and have good processability, and are therefore used in a wide range of applications such as electrical and electronic parts as engineering plastics. In addition, a resin composition obtained by blending a fibrous filler such as glass fiber with a polybutylene terephthalate resin is used to form a reinforced molded product, thereby improving heat resistance and strength.

However, polybutylene terephthalate resin has excellent physical properties and chemical properties, and especially when exposed to a high temperature environment in a state of being in contact with the above-mentioned ATF and other automotive lubricating oils, decomposition becomes obvious, which may lead to Possibility of strength reduction. Therefore, for example, it is not used as a resin constituting a molded article that is used in contact with automotive lubricating oil such as ATF for a long time as described above.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 11-343408

SUMMARY OF THE INVENTION

Invention to solve problem

An object of the present invention is to provide a molded article suitable for use in contact with high-temperature automotive lubricating oil such as ATF using polybutylene terephthalate resin having excellent physical properties, chemical properties, etc. Excellent ATF resistance resin composition.

solution to the problem

The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems. As a result, it was found that a molded article composed of a resin composition in which a carbodiimide compound is blended with a polybutylene terephthalate resin is in contact with automotive lubricating oil such as ATF for a long period of time. It also has the effect of effectively suppressing the reduction in strength, etc., even in the same state, and found a new application as a resin composition constituting a molded article used in contact with lubricating oil for automobiles, such as AT connectors, and completed the present invention. Specifically, the present invention provides the following inventions.

(1) The first invention of the present invention is a polybutylene terephthalate resin composition for constituting a molded article used in contact with lubricating oil for automobiles, the composition comprising polyterephthalate A butylene formate resin and a carbodiimide compound, wherein the molded article has a tensile strength retention rate of 50% or more after being immersed in a lubricating oil for automobiles at 150° C. for 250 hours.

(2) The second invention of the present invention is a polybutylene terephthalate resin composition, wherein, in the first invention, the content of the carbodiimide compound is relative to the polybutylene terephthalate. 100 mass parts of ester resins are 0.01 mass part or more and 5.0 mass parts or less.

(3) The 3rd invention of this invention is a polybutylene terephthalate resin composition, in the 1st or 2nd invention, with respect to the said polybutylene terephthalate resin 100 further A hindered phenol type antioxidant is contained in the ratio of 0.01 mass part or more and 1.0 mass part or less.

(4) The fourth invention of the present invention is a polybutylene terephthalate resin composition, in any one of the first to third inventions, further comprising: relative to the polybutylene terephthalate The alkali compound is contained in 100 parts by mass of the ester resin in a ratio of 0.001 part by mass or more and 0.05 part by mass or less.

(5) A fifth invention of the present invention is a polybutylene terephthalate resin composition, in any one of the first to fourth inventions, further comprising: The thioether-based antioxidant is contained in 100 parts by mass of the ester resin in a ratio of 0.01 part by mass or more and 1.0 part by mass or less.

(6) A sixth invention of the present invention is a polybutylene terephthalate resin composition, in any one of the first to fifth inventions, further comprising: The phosphorus-based compound is contained in 100 parts by mass of the ester resin in a ratio of 0.01 part by mass or more and 1.0 part by mass or less.

(7) A seventh invention of the present invention is a polybutylene terephthalate resin composition in any one of the first to sixth inventions, wherein the properties of the polybutylene terephthalate resin are The viscosity is 0.65 dl/g or more and 1.20 dl/g or less.

(8) The eighth invention of the present invention is a polybutylene terephthalate resin composition in any one of the first to seventh inventions, wherein the terminal of the polybutylene terephthalate resin is The carboxyl group was 30 mmol/kg.

(9) The ninth invention of the present invention is a molded article used in contact with lubricating oil for automobiles, comprising the polybutylene terephthalate resin composition of any one of the first to eighth inventions.

effect of invention

According to the polybutylene terephthalate resin composition of the present invention, even if its molded article is used in contact with high-temperature automotive lubricating oil such as ATF, the reduction in strength and the like can be suppressed, and it can be suitably used for the use.

Detailed ways

Hereinafter, specific embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can change in the range which does not change the summary of this invention.

"1. Polybutylene terephthalate resin composition"

The polybutylene terephthalate resin composition (hereinafter, also simply referred to as "resin composition") of the present invention contains (A) polybutylene terephthalate resin and (B) carbodiimide compound. This resin composition is used to constitute a molded article for a special application used in contact with lubricating oil for automobiles.

Specifically, ATF (automatic transmission fluid) is mentioned as a lubricating oil for automobiles, and an AT connector is mentioned as a molded article used in the state contacting this ATF. Moreover, engine oil, brake oil, gear oil, etc. are mentioned as a lubricating oil for automobiles. Automotive lubricating oils exemplified by these ATFs contain various additives (chemical components) in addition to oil components. For example, as the chemical components, antioxidants, cleaning and dispersing agents, antifoaming agents, rust inhibitors, corrosion inhibitors, viscosity enhancers, pour point depressants, oiliness enhancers, antiwear/extreme pressure agents, colorants, etc. can be mentioned. . From this point of view, it is distinguished from general lubricating oils composed of only oil components such as mineral oil and synthetic oil.

Lubricating oil for automobiles such as ATF is in a state of very high temperature (for example, a temperature exceeding 100° C.), and contains various chemical components as described above. Therefore, for example, in a molded article used in a state of being immersed in ATF, the resin constituting the molded article is easily decomposed under the high temperature environment and in an environment exposed to various additive components, resulting in a decrease in strength and the like.

The inventors of the present invention have found that, in the case of a resin composition obtained by adding a carbodiimide compound to a polybutylene terephthalate resin, in a molded article obtained by molding the resin composition, even when the resin composition contains When various chemical components are used in contact with automotive lubricating oil such as ATF, which is in a high temperature state, the decomposition of the resin component is also suppressed, and the reduction in strength and the like can be effectively prevented.

Here, in this specification, even if the molded product is used in contact with lubricating oil for automobiles that is in a high temperature state and contains various chemical components, it is possible to prevent the decomposition of the resin component constituting the molded product, and to suppress the reduction of strength, etc. The characteristic is called "ATF resistance". It should be noted that the same term is sometimes used for the same properties of automotive lubricants other than ATF. However, in automotive lubricants, ATF contains a lot of additives and is exposed to a high temperature environment. Therefore, In the molded article used in contact with this ATF, a higher level of resistance is required.

Specifically, when the molded article molded using the polybutylene terephthalate resin composition of the present invention was immersed in lubricating oil for automobiles at 150° C. for 250 hours, the tensile strength before and after immersion was maintained. rate becomes 50% or more. As described above, the polybutylene terephthalate resin composition of the present invention is excellent in ATF resistance, and a novel new product has been found as a resin composition for constituting a molded article used in contact with automotive lubricating oil such as ATF. the use of. Hereinafter, each constituent component will be specifically described.

(A) Polybutylene terephthalate resin

The polybutylene terephthalate resin that is the base resin of the resin composition of the present invention is a mixture of at least a dicarboxylic acid component containing terephthalic acid or its ester-forming derivative (lower alcohol ester, etc.), and at least A polybutylene terephthalate-based polymer obtained by polycondensing a diol component of an alkylene glycol (1,4-butanediol) having 4 carbon atoms or an ester-forming derivative thereof.

The polybutylene terephthalate resin is not limited to the homopolybutylene terephthalate resin. For example, the polybutylene terephthalate resin may contain para- Copolymers of butylene phthalate units.

The polybutylene terephthalate resin is not particularly limited, but the amount of terminal carboxyl groups is preferably 30 meq/kg or less, more preferably 25 meq/kg or less. Here, the amount of terminal carboxyl groups can be measured, for example, as follows. That is, after dissolving a pulverized sample of polybutylene terephthalate in benzyl alcohol at a temperature of 215° C. for 10 minutes, it can be measured by titration with a 0.01 N aqueous sodium hydroxide solution.

When a polybutylene terephthalate resin having an amount of terminal carboxyl groups exceeding 30 meq/kg is used, the effect of ATF resistance may be reduced regardless of how the amount of the carbodiimide compound added later is controlled. In addition, the strength reduction due to hydrolysis in a moist heat environment may become large.

In addition, the lower limit of the amount of terminal carboxyl groups is not particularly limited. Generally, when it is less than 5 meq/kg, it is difficult to manufacture, and when it is less than 5 meq/kg, the reaction with the filler described later does not proceed sufficiently, and polyterephthalene Adhesion at the interface between the butylene formate resin and the filler becomes insufficient, and sufficient mechanical strength may not be obtained. Accordingly, the amount of terminal carboxyl groups in the polybutylene terephthalate resin is preferably 5 meq/kg or more, and more preferably 10 meq/kg or more.

The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited, but is preferably 0.65 dl/g or more and 1.20 dl/g or less, more preferably 0.75 dL/g or more and 1.0 dL/g or less . When the intrinsic viscosity is 0.65 dL/g or more, sufficient ATF resistance is easily obtained, and when the intrinsic viscosity is 1.20 dL/g or less, the fluidity during molding required for a molded article based on the resin composition is easily obtained. In addition, polybutylene terephthalate resin which has a desired intrinsic viscosity can be obtained by blending the polybutylene terephthalate resin which has a different intrinsic viscosity. For example, 0.90 dL can be achieved by blending a polybutylene terephthalate resin with an intrinsic viscosity of 1.00 dL/g and a polybutylene terephthalate resin with an intrinsic viscosity of 0.70 dL/g /g or less intrinsic viscosity. In addition, the intrinsic viscosity can be measured under the conditions of temperature 35 degreeC in o-chlorophenol, for example.

In the polybutylene terephthalate resin, examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include aromatic dicarboxylic acid components (meta- C6-C12 aryl dicarboxylic acids such as phthalic acid, phthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, etc.), aliphatic dicarboxylic acid components (succinic acid, adipic acid, azelaic acid, C4-C16 alkyl dicarboxylic acids such as sebacic acid, C5-C10 cycloalkyl dicarboxylic acids such as cyclohexane dicarboxylic acid, etc.), or their ester-forming derivatives, and the like. These dicarboxylic acid components may be used alone or in combination of two or more.

Among them, preferred dicarboxylic acid components (comonomer components) include aromatic dicarboxylic acid components (especially C6-C10 aryl dicarboxylic acids such as isophthalic acid), aliphatic dicarboxylic acid components ( In particular, C6-C12 alkyl dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid).

Examples of diol components (comonomer components) other than 1,4-butanediol include aliphatic diol components [for example, alkylene glycols (ethylene glycol, propylene glycol, trimethylene glycol, C2-C10 alkylene glycol such as 1,3-butanediol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. polyoxy C2-C4 alkylene glycol, etc.), cyclohexanedimethanol, alicyclic diols such as hydrogenated bisphenol A, etc.], aromatic diol components [bisphenol A, 4,4-dihydroxybiphenyl] C2-C4 alkylene oxide adducts such as aromatic alcohols, bisphenol A, etc. (for example, 2 moles of ethylene oxide adducts of bisphenol A, 3 moles of propylene oxide adducts of bisphenol A, etc.), etc. ], or their ester-forming derivatives, etc. These diol components may be used alone or in combination of two or more.

Among them, particularly preferred diol components (comonomer components) include aliphatic diol components (especially polyoxy C2-C3 alkylene diols such as C2-C6 alkylene glycol and diethylene glycol). alicyclic diols such as alcohol, cyclohexanedimethanol, etc.).

All polybutylene terephthalate-based polymers produced by polycondensation using the above-mentioned compounds as monomer components can be suitably used as polybutylene terephthalate constituting the polybutylene terephthalate resin composition. Ester resin component is used. In addition, the combined use of a homopolybutylene terephthalate polymer and a polybutylene terephthalate copolymer is also useful.

(B) Carbodiimide compound

The resin composition of the present invention is characterized by blending a carbodiimide compound with the polybutylene terephthalate resin. By containing the carbodiimide compound in this way, excellent ATF resistance can be imparted to the molded product, and even if it is used in contact with automotive lubricating oil such as ATF in a high temperature state exceeding 100° C., decomposition of resin components and the like can be suppressed. , to prevent the reduction of strength, etc.

The carbodiimide compound is a compound having a carbodiimide group (-N=C=N-) in the molecule. Examples of the carbodiimide compound include aliphatic carbodiimide compounds whose main chain is aliphatic, alicyclic carbodiimide compounds whose main chain is alicyclic, and aromatic carbodiimide compounds whose main chain is aromatic. Any of imine compounds and the like can be used, and among them, aromatic carbodiimide compounds are preferred because they are more excellent in ATF resistance and hydrolysis resistance.

Specifically, as aliphatic carbodiimide compounds, diisopropylcarbodiimide, dioctyldecylcarbodiimide, etc. are mentioned. Moreover, dicyclohexylcarbodiimide etc. are mentioned as an alicyclic carbodiimide compound. In addition to these monofunctional aliphatic carbodiimide compounds and alicyclic carbodiimides, polyfunctional carbodiimides can also be used which can be selected from hexamethylene by using Diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,3-bis(isocyanate One kind or two or more kinds of cyclohexane, xylylene diisocyanate and tetramethyl xylylene diisocyanate are synthesized by decarbonation condensation reaction.

In addition, as the aromatic carbodiimide compound, diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, N-trityl-N'-phenyl group can be mentioned Carbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, Di-p-methoxyphenylcarbodiimide, Di-3,4-dichlorophenylcarbodiimide, Di-2,5-dichlorophenylcarbodiimide, Di-o-chlorophenylcarbodiimide Diimide, p-phenylene-bis-bis-o-tritylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-bis-p-chlorobenzene mono- or dicarbodiimide compounds such as ethylene-bis-diphenylcarbodiimide, poly(4,4'-diphenylmethanecarbodiimide), poly(3,4'-diphenylmethanecarbodiimide) 5'-dimethyl-4,4'-biphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,5 '-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide) , poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), poly(triisopropylene) Polycarbodiimide compounds such as phenylene carbodiimide). Among them, it is particularly suitable to use: di-2,6-dimethylphenylcarbodiimide, poly(4,4'-diphenylmethanecarbodiimide), poly(phenylenecarbodiimide), and poly(triisopropylphenylenecarbodiimide). In addition, these can be used individually by 1 type or in combination of 2 or more types.

Moreover, although it does not specifically limit as a carbodiimide compound, It is preferable to use the carbodiimide compound whose molecular weight is 2000 or more. When the molecular weight is less than 2,000, gas and odor may be generated during melt-kneading or when the residence time during molding is long.

In the polybutylene terephthalate resin composition, the compounding amount of the carbodiimide compound is preferably 0.01 part by mass or more with respect to 100 parts by mass of the (A) polybutylene terephthalate resin and 5.0 parts by mass or less, more preferably 0.1 parts by mass or more and 3.0 parts by mass or less, still more preferably 0.3 parts by mass or more and 2.5 parts by mass or less.

When the compounding quantity of a carbodiimide compound is less than 0.01 mass part, there exists a possibility that the ATF resistance which is the objective of this invention may not fully be acquired. In addition, the effect of hydrolysis resistance cannot be sufficiently obtained. On the other hand, when the compounding amount is more than 5.0 parts by mass, the effect of improving the ATF resistance is small, and the fluidity is reduced and/or the formation of gel components and carbides at the time of compounding and molding, and stretching is likely to occur. Mechanical properties such as strength and flexural strength may decrease. Moreover, the generation amount of isocyanate gas derived from a carbodiimide compound increases, and there exists a possibility that a work environment may deteriorate.

(C) Antioxidants

In the polybutylene terephthalate resin composition of the present invention, an antioxidant may be blended as an additive. Specifically, as the antioxidant, (C-1) hindered phenol-based antioxidant and/or (C-2) thioether-based antioxidant are blended.

(C-1) Hindered phenolic antioxidant

Specifically, it is preferable to mix|blend a hindered phenol type antioxidant in the resin composition of this invention. ATF resistance can be improved by mix|blending a hindered phenol type antioxidant with a carbodiimide compound.

Here, as described above, in the resin composition obtained by blending the carbodiimide compound with the polybutylene terephthalate resin, even if the blending amount of the carbodiimide compound is increased, the amount exceeds a predetermined ratio. , an improvement in ATF resistance higher than that cannot be expected. However, the mechanism is not clear, but by blending a hindered phenol-based antioxidant with a carbodiimide compound in the resin composition, the ATF resistance can be improved depending on the blending amount of the carbodiimide compound.

As the hindered phenol-based antioxidant, a monocyclic hindered phenol compound, a polycyclic hindered phenol compound linked by a hydrocarbon group or a group containing a sulfur atom, a hindered phenol compound having an ester group or an amide group, and the like can be used.

More specifically, examples of hindered phenol-based antioxidants include 2,6-di-tert-butyl-p-cresol, C _2-10 alkylene bis(tert-butylphenol) [eg 2,2' - Methylenebis(4-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol), etc.], Tris(di-tert-butylphenol) -Hydroxybenzyl)benzene [eg, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, etc.], C _{2- 10} Alkanediol-bis[(di-tert-butyl-hydroxyphenyl)propionate [eg 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxybenzene base) propionate] etc.], di- or trioxy C _2-4 alkanediol-bis(tert-butyl-hydroxyphenyl)propionate [eg triethylene glycol-bis[3-(3-tert-butyl) [methyl-5-methyl-4-hydroxyphenyl)propionate], etc.], C _3-8 alkanetriol-bis[(di-tert-butyl-hydroxyphenyl) propionate, C _4-8 alkane Tetraol tetrakis[(di-tert-butyl-hydroxyphenyl)propionate][eg pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc.], Long-chain alkyl(di-tert-butylphenyl)propionate [eg, n-octadecyl-3-(4',5'-di-tert-butylphenyl)propionate, stearyl- 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionate, etc.], 2-tert-butyl-6-(3-tert-butyl-5-methyl-2-hydroxybenzyl) )-4-methylphenylacrylate, 4,4'-thiobis(3-methyl-6-tert-butylphenol) and the like. Among them, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane is particularly suitable. In addition, these hindered phenol type antioxidants can be used individually by 1 type, or in combination of 2 or more types.

The blending amount of the hindered phenol-based antioxidant is preferably 0.01 part by mass or more and 1.0 part by mass or less, more preferably 0.1 part by mass or more and 0.7 part by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin copies or less. When the compounding amount is less than 0.01 part by mass, the effect of improving the ATF resistance may not be sufficiently obtained. On the other hand, when the compounding amount exceeds 1.0 mass part, the effect of improving the ATF resistance more than that cannot be obtained, and there is a possibility of causing a decrease in fluidity and the like.

(C-2) Thioether-based antioxidant

Moreover, as an antioxidant, you may mix|blend a sulfide type antioxidant. Similar to the above-mentioned hindered phenol-based antioxidant, the resin composition of the present invention can improve ATF resistance by blending a sulfide-based antioxidant together with a carbodiimide compound, depending on the blending amount of the carbodiimide compound. .

In addition, as an antioxidant, it is more preferable to combine and mix|blend a hindered phenol type antioxidant and a thioether type antioxidant, and ATF resistance can be improved further by this.

The thioether-based antioxidant is a compound having at least one thioether bond in its molecular structure. Specifically, as the thioether-based antioxidant, for example, dilong-chain alkyl thiodipropionate (dilauryl-3,3'-thiodipropionate, distearyl-3, 3'-thiodipropionate, etc.), tetrakis[methylene-3-(long-chain alkylthio)propionate]alkane (such as tetrakis[methylene-3-(dodecylthio) ) propionate] methane, etc.) etc. In addition, as a long-chain alkyl group, a linear or branched _C8-20 alkyl group etc. are mentioned. These sulfide-based antioxidants may be used alone or in combination of two or more.

In the resin composition, the compounding amount of the sulfide-based antioxidant is preferably 0.01 part by mass or more and 1.0 part by mass or less, more preferably 0.1 part by mass relative to 100 parts by mass of the (A) polybutylene terephthalate resin part or more and 0.7 part by mass or less. When the compounding amount is less than 0.01 part by mass, the effect of improving the ATF resistance may not be sufficiently obtained. On the other hand, when the compounding amount exceeds 1.0 mass part, the effect of improving the ATF resistance more than that cannot be obtained, and there is a possibility of causing a decrease in fluidity and the like.

(D) Basic compound

Moreover, in the polybutylene terephthalate resin composition of this invention, an alkali compound can be mix|blended as an additive.

In the same manner as the above-mentioned antioxidants, in the resin composition, when the base compound is blended with the carbodiimide compound, and the carbodiimide compound alone is blended with the polybutylene terephthalate resin, the carbodiimide compound may be blended as The ATF resistance reaching the peak value is further improved beyond the predetermined ratio.

Examples of the alkali compound include organic acid salts, inorganic acid salts, oxides, hydroxides, hydrides, or alcoholates of alkali metals or alkaline earth metals.

More specifically, examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate, lithium hydrogencarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, Potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium boron hydride, sodium phenyl boronide, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate , Dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, sodium salt, potassium salt, lithium salt of phenol, etc.

In addition, examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogencarbonate, barium hydrogencarbonate, magnesium hydrogencarbonate, strontium hydrogencarbonate, calcium carbonate, barium carbonate, carbonic acid Magnesium, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate, etc.

These basic compounds may be used alone or in combination of two or more. Moreover, it is preferable to use an alkali compound together with the said hindered phenol-type antioxidant and a thioether-type antioxidant, and it is possible to further improve ATF resistance based on a synergistic effect by this.

As a compounding quantity of an alkali compound, 0.001 mass part or more and 0.05 mass part or less are preferable with respect to 100 mass parts of (A) polybutylene terephthalate resin, and 0.01 mass part or more and 0.03 mass part or less are more preferable. When the compounding amount is less than 0.001 part by mass, the effect of improving the ATF resistance may not be sufficiently obtained. On the other hand, when the compounding amount exceeds 0.05 parts by mass, the effect of improving the ATF resistance more than that cannot be obtained, and there is a possibility of causing a decrease in fluidity and the like.

(E) Phosphorus compound

Moreover, in the polybutylene terephthalate resin composition of this invention, a phosphorus compound (phosphorus-containing compound) can be mix|blended as an additive. Thus, ATF resistance can be improved by mix|blending a phosphorus compound.

More specifically, the phosphorus-based compound includes, for example, phosphites [for example, tris(2,4-di-tert-butylphenyl)phosphite, bis(2-tert-butylphenyl)phenyl Mono-tris(branched C _3-6 alkyl-phenyl) phosphites such as phosphites; bis(2,6-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,4 -Di-tert-butylphenyl) pentaerythritol diphosphite, tetrakis (2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphite and other aliphatic polyols ( Branched C _3-6 alkyl-aryl) phosphites, etc.], phosphonates [such as tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphenylene Phosphonates, etc.], phosphates [such as triphenyl phosphate compounds such as tris(2,4-di-tert-butylphenyl) phosphate, etc.], phosphates (such as calcium dihydrogen phosphate, dihydrogen phosphate, etc.) Bases such as sodium monohydrate, or metal phosphates such as alkaline earth metal phosphates (or hydrates thereof), etc.).

These phosphorus-based compounds may be used alone or in combination of two or more. In addition, the phosphorus-based compound is preferably used together with the above-mentioned hindered phenol-based antioxidant, thioether-based antioxidant, and alkali compound, whereby ATF resistance can be further improved due to a synergistic effect.

In the resin composition, the compounding amount of the phosphorus-based compound is preferably 0.01 part by mass or more and 1.0 part by mass or less, more preferably 0.05 part by mass or more with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. And 0.1 mass part or less. When the compounding amount is less than 0.01 part by mass, the effect of improving the ATF resistance may not be sufficiently obtained. On the other hand, when the compounding amount exceeds 1.0 mass part, the effect of improving the ATF resistance more than that cannot be obtained, and there is a possibility of causing a decrease in fluidity and the like.

(F) Filler

In the polybutylene terephthalate resin composition of the present invention, a filler may be blended as an additive. In the resin composition, mechanical strength and rigidity can be improved by blending a filler.

Examples of the filler include fibrous fillers, and non-fibrous fillers such as plate, powder, and spherical fillers.

Examples of the fibrous filler include glass fibers, carbon fibers, potassium titanate fibers, silica-alumina fibers, zirconia fibers, metal fibers, organic fibers, and the like. Among them, glass fibers are preferably used.

Specifically, as the glass fiber, any known glass fiber is preferably used, regardless of the diameter of the glass fiber, the shape of the glass fiber such as the cylindrical, cocoon-shaped cross-section, and the oblong cross-section, or the length when used for producing chopped fibers, rovings, etc., Method of cutting glass. In addition, the type of glass is not particularly limited, but E glass and corrosion-resistant glass containing zirconium element in the composition are suitably used in terms of quality.

In addition, in order to improve the interface properties between the fibrous filler and the resin, a fibrous filler surface-treated with an organic treatment agent such as an aminosilane compound and an epoxy compound can be suitably used. It does not specifically limit as an aminosilane compound and an epoxy compound used for such a fibrous filler, A well-known thing can be used.

Moreover, as a non-fibrous filler, talc, mica, glass flakes, glass beads, calcium carbonate, etc. are mentioned, Of these, talc and mica are preferable.

In the resin composition, the blending amount of the filler is preferably 0 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more, with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. 50 parts by mass or less. When the compounding amount is within such a range, the mechanical properties can be improved without impairing the formability.

(G) Other

To the polybutylene terephthalate resin composition of the present invention, in addition to the above-mentioned additives, known substances generally added to thermoplastic resins, thermosetting resins, and the like may be added in order to impart desired properties according to the purpose. For example, thermoplastic resins other than polybutylene terephthalate and thermosetting resins, heat-resistant stabilizers, stabilizers such as ultraviolet absorbers, antistatic Colorants such as agents, dyes, pigments, plasticizers, fluidity improvers, crystallization accelerators, crystal nucleating agents, hydrolysis resistance improvers such as epoxy compounds, lubricants, mold release agents, etc.

"2. Preparation method of polybutylene terephthalate resin composition"

The polybutylene terephthalate resin composition of the present invention can be easily prepared by commonly used equipment and methods in the same manner as in the preparation method of a conventional resin composition.

Specifically, for example, each component constituting the resin composition can be mixed and kneaded using a single-screw or twin-screw extruder or other melt-kneading apparatus to prepare pellets for molding. Multiple extruders or other melt-kneading devices can be used. In addition, all the components may be simultaneously charged from the hopper, or a part of the components may be charged from the side feed port.

In the case of pelletizing by kneading in an extruder, the extruder barrel temperature is set so that the resin temperature in the extruder is preferably 240°C to 300°C, more preferably 250°C to 270°C. When the resin temperature is lower than 240°C, the reaction between the polybutylene terephthalate resin and the carbodiimide compound becomes insufficient, and there is a possibility that the ATF resistance and hydrolysis resistance cannot be sufficiently exhibited. On the other hand, when the resin temperature exceeds 300° C., there is a concern that decomposition of the resin is likely to occur.

In addition, the (B) carbodiimide compound constituting the resin composition can also be compounded as a resin-based master batch. It is suitable to use masterbatches based on polybutylene terephthalate resins, but also substances prepared in masterbatch form from other resins can be used. Specifically, for example, in the case of a polybutylene terephthalate resin-based master batch, the compounding amount of the resin and the compounding amount of the carbodiimide compound may be adjusted within a predetermined range. In addition, the master batch can be preliminarily charged during melt-kneading to form uniform pellets.

"3. Properties of polybutylene terephthalate resin composition"

The polybutylene terephthalate resin composition of the present invention imparts excellent ATF resistance to a molded article obtained by molding the resin composition. That is, even if it is used in a state of being immersed in, for example, a high temperature state exceeding 100° C. and in contact with automotive lubricating oil such as ATF containing various chemical components, the decomposition of the resin constituting the molded product can be suppressed and effectively prevented. decrease in strength, etc.

More specifically, when immersed in an automotive lubricating oil heated to 150° C. for 250 hours, it exhibits excellent ATF resistance such that the tensile strength retention rate is 50% or more. In addition, the tensile strength can be measured by the tensile test based on ISO527.

In this way, the polybutylene terephthalate resin composition of the present invention is suitable for molded articles, such as AT connectors, etc., which are used in a state of being in contact with automotive lubricating oil such as ATF, which is in a high temperature state and contains various chemical components. Molded articles are particularly useful.

Example

Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these Examples at all.

Examples 1 to 14, Comparative Examples 1 to 6

[Production of resin composition, production of molded article]

The components shown in the following Tables 1 to 2 were weighed and then dry-blended, and melt-kneaded using a 30 mmφ twin-screw extruder (made by Nippon Steel Corporation, TEX-30) to prepare pellets (barrel temperature). 260°C, discharge rate 15kg/h, screw speed 150rpm).

Next, the produced pellets were put into an injection molding machine (J55AD, manufactured by Nippon Steel Corporation), and an ISO tensile test piece was produced.

Here, as the constituent components of the resin composition, the following are used.

(A) Polybutylene terephthalate (PBT) resin

·(A-1) manufactured by WinTech Polymer Ltd., intrinsic viscosity 0.83, terminal carboxyl group amount 14 meq/kg

·(A-2) manufactured by WinTech Polymer Ltd., intrinsic viscosity 1.14, terminal carboxyl group amount 8 meq/kg

(B) Carbodiimide compound

· (B-1) Aromatic carbodiimide compound; manufactured by Rhein Chemie Japan Co., Ltd., Stabaxol P400

·(B-2) Aliphatic carbodiimide compound; Carbodilite LA-1, manufactured by Nippon Textile Co., Ltd.

(C) Antioxidants

·(C-1) Hindered phenol-based antioxidant; BASF Japan Co., Ltd., IRGANOX 1010

·(C-2) Thioether-based antioxidant; ADK STAB AO-412S manufactured by ADEKA Co., Ltd.

(D) Basic compound

·(D-1) Potassium acetate; manufactured by Wako Pure Chemical Industries, Ltd.

(E) Phosphorus compound

·(E-1) Organic phosphite compound; ADK STAB PEP36 manufactured by ADEKA Co., Ltd.

(F) Fibrous filler

·(F-1) Glass fiber; manufactured by Nippon Electric Glass Co., Ltd., ECS03-T127

[Evaluation of molded products]

· Tensile strength after ATF dipping

The manufactured molded product was immersed in ATF (Matic D, manufactured by Nissan Motor Co., Ltd.) at 150° C. for 96 hours, 250 hours, 500 hours, and 750 hours, and the tensile strength (MPa) after each immersion time was measured. In addition, the tensile strength before ATF immersion was also measured together. In addition, the tensile strength was measured by the tensile test based on ISO527.

Then, the tensile strength retention ratio (%) after each immersion time with respect to the tensile strength before ATF immersion was calculated.

· Tensile strength after pressure cooker (PCT) test

Using a pressure cooker tester, the manufactured molded articles were exposed for the respective times shown in Tables 1 and 2 below under the conditions of 121° C. and 100% RH. After each exposure time, a tensile test according to ISO527 was performed to measure the tensile strength.

[Table 1]

[Table 2]

As shown in Table 1, in the resin composition of the Example in which the carbodiimide compound was blended with the polybutylene terephthalate resin, even if the injection-molded product was immersed in high-temperature ATF for a long time state, the reduction in strength can be suppressed, and excellent ATF resistance is exhibited. In addition, as shown in the results of Examples 5 to 14, it was found that ATF resistance can be improved by blending an antioxidant, an alkali compound, and the like together with the carbodiimide compound.

In addition, as shown in the results of Examples 7 to 14, it can be seen that, compared with the resin composition in which the antioxidant and the phosphorus-based compound are blended with the carbodiimide compound, by also using the alkali compound in combination (Example 11 -14), ATF resistance improves by the compounding quantity of a carbodiimide compound.

From these results, it was found that the polybutylene terephthalate resin compositions of the examples are particularly useful for special applications as molded articles used in contact with automotive lubricating oils such as ATF.

On the other hand, as shown in the results of the comparative examples in Table 2, it was found that the polybutylene terephthalate resin composition to which the carbodiimide compound was not added was immersed in high-temperature ATF for a long time, The strength is significantly reduced. In addition, it was found that even if an antioxidant and an alkali compound were added to the polybutylene terephthalate resin (for example, refer to the results of Comparative Examples 4 to 6), ATF resistance could not be obtained, and the addition of a carbodiimide compound had a negative effect on the resistance to ATF sex is important.

Claims (4)

1. A polybutylene terephthalate resin composition for constituting an AT connector used in contact with an automatic transmission oil,

the composition comprises: a homopolybutylene terephthalate resin; an aromatic carbodiimide compound in a proportion of 0.3 to 5.0 parts by mass per 100 parts by mass of the homopolybutylene terephthalate resin; an alkali compound in a proportion of 0.001 to 0.05 parts by mass per 100 parts by mass of the homopolybutylene terephthalate resin; a hindered phenol antioxidant in a proportion of 0.01 to 1.0 part by mass per 100 parts by mass of the homopolybutylene terephthalate resin; a thioether antioxidant in a proportion of 0.01 to 1.0 part by mass per 100 parts by mass of the homopolybutylene terephthalate resin; a phosphorus-based compound in a proportion of 0.01 to 1.0 part by mass per 100 parts by mass of the homopolybutylene terephthalate resin,

the molded article has a tensile strength retention of 50% or more after immersion in 150 ℃ automatic transmission oil for 250 hours.

2. The polybutylene terephthalate resin composition according to claim 1, wherein the homopolybutylene terephthalate resin has an intrinsic viscosity of 0.65dl/g or more and 1.20dl/g or less.

3. The polybutylene terephthalate resin composition according to claim 1 or 2, wherein the terminal carboxyl group of the polybutylene terephthalate resin is 30mmol/kg or less.

4. An AT connector used in contact with an automatic transmission oil, which is composed of the polybutylene terephthalate resin composition according to any one of claims 1 to 3.