JP2006219611A - Polybutylene terephthalate resin composition and molded article made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polybutylene terephthalate resin composition having well-balanced flexural properties and elastic modulus at a low temperature and excellent hydrolysis resistance and a molded article produced by using the composition. <P>SOLUTION: The polybutylene terephthalate resin composition is produced by compounding (A) 100 pts.wt. of a polybutylene terephthalate resin having a terminal carboxyl content of ≤30 eq/ton with (B) 1-30 pts.wt. of a polyester-ether-type polyester thermoplastic elastomer containing 25-80 wt.% polyalkylene ether glycol having a weight-average molecular weight of 400-6,000 as a constitutional unit. The composition further provides a molded article produced by molding the resin composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polybutylene terephthalate resin composition excellent in bending characteristics at low temperature and hydrolysis resistance, and a molded article obtained therefrom.

  Thermoplastic polybutylene terephthalate resin (hereinafter sometimes abbreviated as PBT resin) is excellent in mechanical properties, electrical properties, other physical and chemical properties, and has good processability. It is used in a wide range of applications such as automobiles, electrical / electronic parts, etc. However, there is a problem that the mechanical strength is inferior at a low temperature. For example, when bending deformation is applied at a low temperature, there may be a trouble that the strain is broken when the amount of strain is small. For this reason, in the connector that fixes the terminal by snap characteristics such as lances, troubles such as breakage of the lance part occur at low temperatures, so the usage and shape of the molded product are considerably limited. Currently.

In order to improve the above-described problem of mechanical strength at low temperatures, a resin having good flexibility, particularly a thermoplastic elastomer, is added to the PBT resin. For example, an alloy with a polyester-ether type (polyester polyether block copolymer) thermoplastic elastomer has been studied from the viewpoint of compatibility with a polyester resin.
In addition, materials for automobile connectors and the like are required to have hydrolysis resistance under high-temperature and high-humidity conditions. However, this property tends to decrease due to the blending of the thermoplastic elastomer described above. It is also important not to reduce the sex.

  Patent Document 1 discloses that a tracking resistance is improved by a resin composition in which a polyester-ether type thermoplastic elastomer and a polyolefin are blended with a PBT resin. Patent Document 2 discloses an insert-molded product in which an inorganic filler is insert-molded into a polyester (mixture) made of a polyester / ether-type thermoplastic elastomer and a PBT resin. It is disclosed to improve the property.

  Patent Document 3 discloses a connector molding resin composition in which one or more of polyolefin, polyolefin-based elastomer, and polyester-based elastomer and a phosphorus-based flame retardant are blended with a PBT resin. It is described that it has an excellent balance between physical properties and heat resistance (maintaining tensile properties after heat treatment at 150 ° C.).

  In these Patent Documents 1 to 3, no consideration is given to the improvement in bending characteristics and hydrolysis resistance at low temperatures, and the physical properties (the amount of terminal carboxyl groups) of the PBT resin and the bending characteristics at low temperatures There is no suggestion of this correlation. Regarding the bending strength, elastic modulus, and tensile strength, the results of the evaluation at around room temperature as evaluated in Patent Documents 1 to 3 and the evaluation at the low temperature focused in the present invention necessarily correspond. It wasn't.

Furthermore, Patent Document 4 discloses a resin composition for connectors containing PBT resin, a polyester block copolymer comprising a polyester segment (b1) and a polyolefin polymer segment (b2), and a polyolefin, and low temperature toughness ( It is disclosed to improve the tensile elongation at low temperature). In Patent Document 4, the low temperature toughness is improved only by the combined use with polyolefin, and the polyester block copolymer does not contain a polyether segment.
Moreover, in these patent documents mentioned above, the amount of terminal carboxyl groups of the PBT resin can take a wide range of values.

JP-A-6-57108 JP-A-9-262863 JP 11-246744 A JP 2000-136296 A

  An object of the present invention is to provide a polybutylene terephthalate resin composition that has an excellent balance between bending properties and elastic modulus at low temperatures and does not deteriorate hydrolysis resistance, and a molded product obtained therefrom.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors blend a polyester thermoplastic elastomer containing a specific amount of a polyalkylene ether glycol structural unit with a PBT resin having a terminal carboxyl group amount of a specific value or less. Therefore, a polybutylene terephthalate resin composition having a performance that has not been noticed in the past, such as excellent balance between bending properties and elastic modulus at low temperature and no decrease in hydrolysis resistance without using polyolefin or the like together. As a result, the present invention was completed.

  That is, the gist of the present invention is that (A) a polybutylene terephthalate resin having a terminal carboxyl group amount of 30 eq / ton or less and (B) a polyalkylene ether glycol having a weight average molecular weight of 400 to 6000 is a structural unit. As a polybutylene terephthalate resin composition containing 1 to 30 parts by weight of a polyester / ether type polyester-based thermoplastic elastomer containing 25 to 80% by weight, and a molded article formed by molding the same , Exist.

  According to the present invention, since a polybutylene terephthalate resin composition having an excellent balance between bending characteristics and elastic modulus at low temperature and having no decrease in hydrolysis resistance is obtained, it can be applied to various parts such as automobiles, OA equipment, and precision machines. Applicable. In particular, the lance-shaped connector obtained from the resin composition of the present invention can reduce the trouble of lance breakage at a low temperature and can improve the quality. Accordingly, the resin composition of the present invention can be preferably applied to the use of automobile parts, and is further suitable for the use of connectors.

Hereinafter, the present invention will be described in detail.

(A) Polybutylene terephthalate resin (PBT resin)
The (A) polybutylene terephthalate resin used in the present invention is a polyester resin mainly composed of terephthalic acid and 1,4-butanediol, and terephthalic acid accounts for 50 mol% or more of the total dicarboxylic acid component, A polyester resin in which 1,4-butanediol accounts for 50% by weight or more of the total diol. Among these, terephthalic acid preferably occupies 80 mol% or more of the total dicarboxylic acid component, and more preferably 95 mol% or more. 1,4-butanediol preferably accounts for 80 mol% or more of the total diol component, and more preferably 95 mol% or more.

  The terminal carboxyl group amount of the (A) PBT resin of the present invention needs to be 30 eq / ton or less, preferably 28 eq / ton or less, more preferably 25 eq / ton or less, and particularly preferably 20 eq / ton or less. is there. The amount of terminal carboxyl groups can be determined by dissolving PBT resin in an organic solvent and titrating with an alkali hydroxide solution. By setting the terminal carboxyl group amount of the PBT resin to 30 eq / ton or less, the reason is not clear. However, due to the synergistic effect with the polyester-ether type polyester-based thermoplastic elastomer (B) described later, the bending property at low temperature is improved. Can be improved. Moreover, hydrolysis resistance can be remarkably improved, and molding residence stability and heat aging stability can be improved.

  Since the carboxyl group in the PBT resin acts as an autocatalyst for the hydrolysis, if a terminal carboxyl group exceeding 30 eq / ton exists, the hydrolysis starts at an early stage, and the hydrolysis proceeds in a chained manner. The degree of polymerization of rapidly decreases. Since the resin composition of the present invention uses a PBT resin having a terminal carboxyl group amount of 30 eq / ton or less, the progress of early hydrolysis and oxidative degradation is suppressed even under high temperature and high humidity conditions. It can be preferably applied to automotive parts such as connectors.

  The intrinsic viscosity of the (A) PBT resin of the present invention is usually 0 when measured at a temperature of 30 ° C. using a mixed solvent of 1,1,2,2-tetrachloroethane / phenol = 1/1 (weight ratio). .50 to 3.0 dl / g, preferably 0.6 to 2.0 dl / g, and more preferably 0.7 to 1.5 dl / g. If the intrinsic viscosity is less than 0.50 dl / g, the mechanical strength tends to decrease. If the intrinsic viscosity is more than 3.0 dl / g, the melt viscosity of the resin composition increases, the fluidity decreases, and the moldability. Tends to decrease. Two or more types of PBT resins may be used in combination, and in that case, the intrinsic viscosity of the combined PBT resin as a whole is preferably within the above-described range.

  Although the (A) PBT resin of the present invention having the above-mentioned specific terminal carboxyl group amount is not particularly limited, it is produced by polymerizing terephthalic acid and 1,4-butanediol as main raw materials. I can do it. Here, the main raw material means that terephthalic acid occupies 50 mol% or more of all dicarboxylic acid components, and 1,4-butanediol occupies 50 mol% or more of all diol components. More preferably, terephthalic acid accounts for 80 mol% or more of the total dicarboxylic acid component, and more preferably 95 mol% or more. More preferably, 1,4-butanediol occupies 80 mol% or more of the total diol component, and more preferably 95 mol% or more. Generally, if there are many copolymer components other than terephthalic acid and 1,4-butanediol, the temperature-falling crystallization temperature decreases, so there is an upper limit for the content of the copolymer component, but the upper limit depends on the copolymerization method. Change.

  In the present invention, the dicarboxylic acid component other than terephthalic acid is not particularly limited, and examples thereof include phthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, and 4,4′-benzophenone dicarboxylic acid. Acid, aromatic dicarboxylic acid such as 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexane Alicyclic dicarboxylic acids such as dicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid be able to.

  In the present invention, the diol component other than 1,4-butanediol is not particularly limited. For example, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, polytetramethylene ether glycol, 1,5- Aliphatic diols such as pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1, Aromatic diols such as 4-cyclohexanedimethylol, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone All can be mentioned.

  In the present invention, further, hydroxycarboxylic acid such as glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acid, Monofunctional components such as stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, gallic acid, trimethylolethane, trimethyl A trifunctional or higher polyfunctional component such as methylolpropane, glycerol, pentaerythritol and the like can be used as a copolymerization component.

  (A) The PBT resin production method includes a batch reaction and a continuous reaction. A batch reaction is a method in which an ester exchange reaction or an esterification reaction and a polycondensation reaction are carried out in a batch manner, and a continuous reaction is a method in which an esterification reaction and a polycondensation reaction are carried out continuously. In the present invention, a method in which terephthalic acid and 1,4-butanediol are continuously polymerized is preferable. The molecular weight decreases with the passage of time from the reaction vessel after the reaction is completed, the amount of terminal carboxyl groups increases, and remains. By avoiding an increase in the amount of tetrahydrofuran, a high-quality resin can be easily obtained.

  Although there is no restriction | limiting in particular as a continuous polymerization method which is a manufacturing method of (A) PBT resin of this invention, The method of superposing | polymerizing continuously using a serial continuous tank reactor is preferable. For example, a dicarboxylic acid component and a diol component are preferably heated at a temperature of 150 to 280 ° C., more preferably 180 to 265 ° C. in the presence of an esterification reaction catalyst in one or a plurality of esterification reaction vessels. Is 6.67 to 133 kPa, more preferably 9.33 to 101 kPa, and the esterification reaction is continued for 2 to 5 hours with stirring. Subsequently, the oligomer which is the obtained esterification reaction product is transferred to a polycondensation reaction tank, and preferably in the presence of a polycondensation reaction catalyst in one or a plurality of polycondensation reaction tanks, preferably 210 to 280. The polycondensation reaction can be carried out continuously for 2 to 5 hours with stirring under a reduced pressure of ℃, more preferably 220 to 265 ℃, preferably 26.7 kPa or less, more preferably 20 kPa or less. The PBT resin obtained by the polycondensation reaction is transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted in the form of a strand, and while being cooled with water or after being cooled with water, it is cut with a pelletizer, etc. It is made of granular material.

  There is no restriction | limiting in particular in the type of the esterification reaction tank to be used, For example, a vertical stirring complete mixing tank, a vertical heat convection mixing tank, a tower type continuous reaction tank, etc. can be mentioned. The esterification reaction tank may be one, or may be a plurality of tanks in which a plurality of tanks of the same kind or different kinds are connected in series. There is no restriction | limiting in particular in the type of the polycondensation reaction tank used for this invention, For example, a vertical stirring polymerization tank, a horizontal stirring polymerization tank, a thin film evaporation type polymerization tank etc. can be mentioned. The number of polycondensation reaction tanks can be one, or a plurality of tanks in which a plurality of tanks of the same or different types are connected in series can be used.

  There is no restriction | limiting in particular in the esterification reaction catalyst used for this invention, For example, a titanium compound, a tin compound, a magnesium compound, a calcium compound etc. can be mentioned. Among these, a titanium compound can be particularly preferably used. Examples of the titanium compound used as the esterification catalyst include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. For example, in the case of tetrabutyl titanate, the amount of titanium compound catalyst used is preferably 90 ppm or less (weight ratio) as titanium atoms, more preferably 10 to 85 ppm, and even more preferably 20 to the theoretical yield of PBT resin. It is more preferable to use ˜70 ppm, particularly 25 to 50 ppm. Titanium is usually derived from a polymerization catalyst for producing a PBT resin. However, if the content of titanium atoms in the PBT resin is more than 90 ppm, the hydrolysis resistance is lowered. The reason is not clear, but it is considered that when the content of titanium atoms derived from the catalyst is large, the decomposition of the PBT resin at a high temperature is promoted and the hydrolysis resistance is lowered. On the other hand, when the content of titanium atoms in the PBT resin is 10 ppm or less, not only the polymerization rate is lowered, but also the adhesiveness with the reinforcing filler is deteriorated and the mechanical strength tends to be lowered.

  The content of titanium atoms can be determined from the amount of catalyst added, but high resolution ICP (Induced Coupled Plasma) -MS (Mass Spectrometer) (SA) is obtained by wet-decomposing PBT with high-purity sulfuric acid and nitric acid for the electronics industry. -It can be measured by using Moquest.

  (A) PBT resin preferably used in the present invention is, for example, terephthalic acid and 1,4-butanediol with tetrabutyl titanate as a catalyst in an amount of 10 to 90 ppm as titanium atoms with respect to the theoretical yield of PBT resin. Can be produced by continuously transesterifying at normal pressure in the temperature range of 180 to 240 ° C. to obtain an oligomer, and then continuously polycondensing the oligomer at 230 to 270 ° C. under reduced pressure. .

  (A) As a polycondensation reaction catalyst used when producing a PBT resin, it is possible to use the esterification reaction catalyst added during the esterification reaction as a polycondensation reaction catalyst without adding a new catalyst. Alternatively, a catalyst that is the same as or different from the esterification reaction catalyst added during the esterification reaction may be further added during the polycondensation reaction. For example, when tetrabutyl titanate is further added, the amount used is preferably 90 ppm (weight ratio) or less, and 85 ppm (weight ratio) or less, as titanium atoms, with respect to the theoretical yield of PBT resin. Is more preferable. Examples of the polycondensation reaction catalyst different from the esterification reaction catalyst include antimony compounds such as antimony trioxide and germanium compounds such as germanium dioxide and germanium tetroxide.

  In the esterification reaction and / or polycondensation reaction, in addition to the above catalyst, orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, or phosphorus compounds such as esters and metal salts thereof, sodium hydroxide, benzoic acid, etc. Reaction aids such as alkali metal or alkaline earth metal compounds such as sodium acid, magnesium acetate, calcium acetate, 2,6-di-t-butyl-4-octylphenol, pentaerythrityl tetrakis [3- (3 ′, 5 Phenol compounds such as' -t-butyl-4'-hydroxyphenyl) propionate], thioether compounds such as dilauryl-3,3'-thiodipropionate, pentaerythrityltetrakis (3-laurylthiodipropionate), tri Phenylphosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t- Antioxidants such as phosphorus compounds such as (butylphenyl) phosphite, paraffin wax, microcrystalline wax, polyethylene wax, long chain fatty acids such as montanic acid and montanic acid ester or esters thereof, mold release agents such as silicone oil and other Additives can be present.

  (A) The PBT resin is produced by a method of transesterifying dimethyl terephthalate and the like with 1,4-butanediol and a direct esterification reaction of terephthalic acid with 1,4-butanediol. There is a way. Among these, the direct esterification reaction method using terephthalic acid and 1,4-butanediol as starting materials is more advantageous from the viewpoint of raw material cost, and the crystallization rate is higher than the method through transesterification. Is preferable in that a polybutylene terephthalate having a high molecular weight can be easily obtained.

  (A) When producing a PBT resin, it is also possible to carry out solid phase polymerization in order to increase the viscosity of the PBT resin and to reduce the carboxyl end group. Solid phase polymerization can be carried out by heating the pellets obtained by melt polymerization as described above under reduced pressure for a long time at a temperature about 20 to 3 ° C. lower than the melting point.

  The temperature-falling crystallization temperature of the (A) PBT resin used in the present invention is preferably 160 to 200 ° C, more preferably 170 to 190 ° C, from the viewpoint that a high elastic modulus is obtained. In the present invention, the temperature-falling crystallization temperature means a crystallization temperature measured with a differential scanning calorimeter at a temperature-falling rate of 20 ° C./min. The temperature-falling crystallization temperature is a temperature-falling rate of 20 from the melted state of PBT. It is the temperature of the exothermic peak due to crystallization that appears when cooled at ° C / min.

  The residual tetrahydrofuran amount in the PBT resin composition used in the present invention is 300 ppm (weight ratio) or less, more preferably 200 ppm (weight ratio) or less. The amount of residual tetrahydrofuran in the PBT resin composition can be determined by immersing the PBT pellets in water, treating them at 120 ° C. for 6 hours, and quantifying the amount of tetrahydrofuran eluted in the water by gas chromatography. By setting the amount of residual tetrahydrofuran in the PBT resin composition to 300 ppm (weight ratio) or less, even if a molded product obtained from the resin composition of the present invention is used at a high temperature, generation of gas such as tetrahydrofuran is reduced. If the amount of residual tetrahydrofuran in the PBT resin composition exceeds 300 ppm (weight ratio), when the molded article is used at a high temperature, generation of gas such as tetrahydrofuran may increase, which may cause cracks.

  The lower limit of the residual tetrahydrofuran amount is not particularly limited, but is usually about 50 ppm (weight ratio). A smaller amount of residual tetrahydrofuran tends to reduce the generation of organic gas, but the remaining amount and the amount of gas generated are not necessarily proportional.

(B) Polyester Thermoplastic Elastomer The polyester thermoplastic elastomer as the component (B) used in the present invention has a hard segment of an aromatic polyester block (B-1) and a soft segment of an aliphatic polyether block (B- 2) A polyester / ether type block copolymer composed of 2), wherein the aliphatic polyether block (B-2) is mainly composed of polyalkylene ether glycol.

  Examples of the dicarboxylic acid or its ester-forming derivative constituting the aromatic polyester block (B-1) in the present invention include phthalic acid, terephthalic acid, isophthalic acid, 1,4- or 2,6-naphthalenedicarboxylic acid, Aromatic dicarboxylic acids such as 4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, or alkyl esters thereof can be exemplified, and low molecular weight glycols or ester-forming derivatives thereof. As aliphatic diols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene glycol, alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, 4,4 '-Dihydr Alkoxy biphenyl, 2,2-bis aromatic diols such as (4'-beta-hydroxy ethoxy phenyl) propane can be exemplified. Each of these components may contain one kind or two or more kinds.

  Among these, the block (B-1) mainly composed of terephthalic acid and tetramethylene glycol is preferable from the viewpoints of compatibility and heat resistance. Specifically, the terephthalic acid in the dicarboxylic acid or its ester-forming derivative component is preferably 50 mol% or more, more preferably 70 mol% or more, and the low molecular weight glycol or tetramethylene in its ester-forming derivative component is preferred. It is preferable that glycol is 50 mol% or more, more preferably 70 mol% or more.

Examples of the polyalkylene ether glycol that is the main component of the aliphatic polyether block (B-2) include polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and ethylene oxide. Examples thereof include polyalkylene ether glycols having 1 to 8 carbon atoms, preferably 2 to 6 carbon atoms, such as blocks or random copolymers with propylene oxide, blocks or random copolymers of ethylene oxide and tetrahydrofuran, among which polytetramethylene Ether glycol is preferred.
Here, the polyalkylene ether glycol is the main component of the aliphatic polyether block (B-2) means that the polyalkylene ether glycol is 50 mol% or more in the aliphatic polyether block (B-2). Further, it means 70 mol% or more, particularly 90 mol% or more.

The weight average molecular weight of the polyalkylene ether glycol is preferably 400 to 6,000, more preferably 500 to 4,000, and particularly preferably 600 to 3,000. Content of the polyalkylene ether glycol structural unit is 25 to 80% by weight, preferably 30 to 70% by weight, and more preferably 40 to 60% by weight. When this content is less than 25% by weight, the bending characteristics at low temperatures of the PBT resin composition are lowered, and the hydrolysis resistance is also lowered. On the other hand, when it exceeds 80% by weight, the affinity with the PBT resin is lowered, and the mechanical properties are lowered.
Furthermore, the content of the polyalkylene ether glycol structural unit in the whole PBT resin composition of the present invention is usually 0.1 to 30% by weight, preferably 0.5 to 20% by weight, more preferably 1.0. -10% by weight.

  (B) The polyester-based thermoplastic elastomer generates a polyester oligomer from a dicarboxylic acid or an ester-forming derivative thereof and a low molecular weight glycol or an ester-forming derivative thereof, and a polyalkylene ether glycol having a predetermined molecular weight is provided in the polyester oligomer. It can be manufactured by quantitatively mixing and copolymerizing with a tin catalyst or the like. For example, trade names “Primalloy” (manufactured by Mitsubishi Chemical Corporation), “Hytrel” (manufactured by Toray DuPont), “Perprene” An elastomer such as “Toyobo Co., Ltd.” can be used.

  The blending amount of the (B) polyester-based thermoplastic elastomer of the present invention is 1 to 30 parts by weight, more preferably 1.5 to 20 parts by weight, particularly 100 parts by weight of (A) PBT resin. It is preferably 2 to 10 parts by weight. When the blending amount of the component (B) is less than 1 part by weight, the effect of improving the bending strain at a low temperature is reduced. On the other hand, when it exceeds 30 parts by weight, the elastic modulus is lowered.

  The intrinsic viscosity of the (B) polyester-based thermoplastic elastomer used in the present invention is a mixed solvent of 1,1,2,2-tetrachloroethane / phenol = 1/1 (weight ratio) at a temperature of 30 ° C. When measured, it is usually 0.5 to 3.0 dl / g, preferably 0.6 to 2.5 dl / g, and more preferably 0.7 to 2.0 dl / g. Even if the intrinsic viscosity is less than 0.5 dl / g or greater than 3.0 dl / g, in any case, the miscibility with the PBT resin is lowered, and the mechanical properties tend to be hardly exhibited.

  In the present invention, the ratio [η (A) / η (B)] of the intrinsic viscosity of the (A) polybutylene terephthalate resin to the intrinsic viscosity of the (B) polyester-based thermoplastic elastomer is usually 0.3 to 3. It is preferably 0, more preferably 0.5 to 2.0, and particularly preferably 0.7 to 1.5. Whether the ratio of these intrinsic viscosities [η (A) / η (B)] is smaller than 0.3 or larger than 3.0, the miscibility with (A) PBT resin is reduced in any case. However, mechanical strength (tensile strength, bending strength, bending strain, etc.) tends to decrease.

(C) Epoxy Compound In addition to the components (A) and (B) described above, it is preferable to add (C) an epoxy compound to the PBT resin composition of the present invention. The (C) epoxy compound that can be used in the present invention may be any of monofunctional, bifunctional, trifunctional, or polyfunctional, or a mixture of two or more of these. In particular, bifunctional, trifunctional, and polyfunctional epoxy compounds, that is, compounds having two or more epoxy groups in one molecule are preferable. Further, the epoxy compound (C) may be any of alcohol, phenolic compound or glycidyl compound obtained from the reaction of carboxylic acid and epichlorohydrin, alicyclic epoxy compound, and the like.

  Specific examples of the epoxy compound (C) include glycidyl ethers such as methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, decyl glycidyl ether, stearyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, and allyl glycidyl ether; Diglycidyl ethers such as neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, propylene glycol diglycidyl ether, bisphenol A diglycidyl ether; fatty acid glycidyl esters such as glycidyl benzoate and glycidyl sorbate; Adipic acid diglycidyl ester, terephthalic acid diglycidyl ester, Examples include diglycidyl esters such as diglycidyl ester of rutophthalic acid; alicyclic diepoxy compounds such as 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexyl carboxylate; glycidylimide compounds such as N-glycidylphthalimide. . Among them, the (C) epoxy compound of the present invention is preferably glycidyl ether or diglycidyl ether, more preferably a glycidyl ether compound obtained from the reaction of bisphenol A and epichlorohydrin, particularly bisphenol A diglycidyl ether. preferable.

  (C) The compounding quantity of an epoxy compound is 0.05-10 weight part with respect to 100 weight part of (A) PBT resin, Furthermore, 0.1-8 weight part, Especially 0.2-5 weight part is. preferable. (C) By using 0.05 parts by weight or more of an epoxy compound, the effect of improving bending characteristics and hydrolysis resistance, especially bending characteristics at low temperatures, is exhibited as a synergistic effect with the components (A) and (B). Is done. (C) When there are more compounding quantities of an epoxy compound than 10 weight part, fluidity | liquidity falls and it exists in the tendency for a moldability to deteriorate. (B) The blending ratio (C) / (B) [weight ratio] of the (C) epoxy compound to the polyester-based thermoplastic elastomer is 0.001 to 1, more preferably 0.005 to 0.8, and particularly preferably 0.00. 01-0.5 is preferable. If it is smaller than 0.001, the effect of improving hydrolysis is small, and if it is larger than 1, fluidity tends to be lowered.

(D) Reinforcement filler In addition to the components (A) and (B) described above, it is preferable to add (D) a reinforcement filler to the PBT resin composition of the present invention. (D) Examples of reinforcing fillers include fibrous, plate-like, granular materials, and mixtures thereof. Specifically, fibrous materials such as glass fibers, carbon fibers, mineral fibers, metal fibers, ceramic whiskers, wollastonite; plate-like materials such as glass flakes, mica, talc; silica, alumina, glass beads, carbon black, Well-known things, such as granular materials, such as calcium carbonate, are mentioned.

  The criteria for selecting the (D) reinforcing filler used in the present invention depends on the required characteristics of the product. However, when the mechanical strength and rigidity are important, fibrous materials, particularly glass fibers, are selected, and When importance is attached to the reduction of anisotropy and warpage, a plate-like material, particularly mica, is selected. In addition, an optimum granular material is selected based on an overall balance in consideration of fluidity at the time of molding.

  The glass fiber is not particularly limited as long as it is generally used for resin reinforcement. For example, a long fiber type (roving) or a short fiber type (chopped strand) can be used, and the fiber diameter is usually 6 to 13 μm. . Further, the glass fiber may be treated with a sizing agent (for example, polyvinyl acetate, polyester, etc.), a coupling agent (for example, silane compound, boron compound, etc.), other surface treatment agents, and the like.

  (D) The compounding amount of the reinforcing filler is usually 1 to 140 parts by weight with respect to 100 parts by weight of (A) PBT, and further 5 to 100 parts by weight, particularly 10 from the viewpoint of rigidity and dimensional stability. -50 parts by weight is preferred. (D) Even if no reinforcing filler is blended, the effect of improving the low-temperature characteristics of the present invention is exhibited. However, when the reinforcing filler is blended, damage troubles are likely to occur, so a resin blended with the reinforcing filler. In the case of the composition, the effect of the present invention is more exhibited. (B) The blending ratio (D) / (B) [weight ratio] of the (D) reinforcing filler to the polyester-based thermoplastic elastomer is 0.1 to 100, more preferably 0.5 to 50, particularly 1 to 20. Is preferred. If it is less than 0.1, the effect of improving the strength is small, and if it exceeds 100, the toughness tends to decrease.

(E) Flame retardant In addition to the above components (A), (B), (C), and (D), the resin composition of the present invention contains (E) a flame retardant within a range that does not impair the object of the present invention. It can be used, and as the flame retardant, halogen type or phosphorus type can be used.

In the present invention, the flame retardant (E) is preferably a halogen flame retardant having a halogen atom in the molecule, and particularly preferably a bromine content of 20% by weight or more.
Preferred examples of the halogen flame retardant include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, glycidyl brominated bisphenol A, pentabromobenzyl. Examples thereof include polyacrylates and brominated imides. Among them, glycidyl brominated bisphenol A, pentabromobenzyl polyacrylate, or brominated imide is preferable because it does not inhibit the effect of the (C) epoxy compound.

  (E) The compounding quantity of a flame retardant is 5-40 weight part normally with respect to 100 weight part of (A) PBT resin. (E) If the flame retardant is less than 5 parts by weight, sufficient flame retardancy is difficult to obtain, and if it exceeds 40 parts by weight, the physical properties, particularly the mechanical strength, tend to decrease. The blending amount of the flame retardant is preferably 7 to 35 parts by weight, more preferably 8 to 25 parts by weight with respect to 100 parts by weight of the PBT resin, from the viewpoint of the balance between flame retardancy and physical properties.

In the resin composition of this invention, you may use together the antimony compound as a flame retardant adjuvant with (E) a flame retardant. Examples of the antimony compound include antimony trioxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), and sodium antimonate.

  The compounding quantity of an antimony compound is 2-40 weight part with respect to 100 weight part of (A) PBT resin. When the antimony compound is less than 2 parts by weight, it is difficult to obtain sufficient flame retardancy, and when it exceeds 40 parts by weight, the physical properties tend to decrease. The blending amount of the antimony compound is preferably 2 to 30 parts by weight, more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the PBT resin from the viewpoint of the balance between flame retardancy and physical properties. (E) The blending ratio of the antimony compound to the flame retardant (antimony compound) / (E) [weight ratio] is preferably 0.2 to 1, and more preferably 0.5 to 0.8. If the ratio is out of this range, the flame retardant effect tends to be hardly exhibited.

  In addition to the components (A) to (E) described above, various known additives such as paraffin wax, polyethylene wax, stearic acid and esters thereof, silicone oil and other mold release agents; hindered phenols, phosphorous acid Thermal stabilizers such as ester and sulfur-containing ester compounds; crystallization accelerators; ultraviolet absorbers or weather resistance-imparting agents; dyes, pigments, foaming agents and the like may be included.

  Various nylons such as nylon 6, nylon 66, nylon 12, nylon MXD6, various nylon elastomers, liquid crystal polymers, polycarbonate resins, styrene resins such as polystyrene, ABS, AS, MS, various acrylic resins, polyethylene, polypropylene, ethylene An olefin resin such as a propylene copolymer or a fluorine resin such as polytetrafluoroethylene may be contained.

  Furthermore, elastomers such as isobutylene-isoprene rubber, styrene-butadiene rubber, styrene-butadiene rubber-styrene, ethylene-propylene rubber, acrylic elastomer, thermoplastic resins such as ionomer resin and phenoxy resin, phenol resin, melamine resin, You may contain thermosetting resins, such as a silicone resin and an epoxy resin.

  The PBT resin composition of the present invention can be obtained by blending each component (A) to (E) described above and various additive components used as necessary, and melt-kneading. The compounding method of each component is performed using the apparatus normally used, for example, a ribbon blender, a Hensel mixer, a drum blender, etc. As the melt-kneading method, various extruders, Brabender blast graphs, lab plast mills, kneaders, Banbury mixers and the like are used. The heating temperature at the time of melt kneading is usually 230 to 290 ° C., but in order to suppress the decomposition of the resin composition at the time of melt kneading, it is preferable to blend a heat stabilizer among the above-mentioned additives.

  Each of the above-described components, including optional components, can be supplied all at once to the melt-kneader or can be sequentially supplied. Moreover, two or more types of components selected from each component including an arbitrary component can be mixed in advance. When a fibrous (D) reinforcing filler such as glass fiber is blended, the PBT resin composition is crushed by adding it from the middle of the extruder after melting the resin composition containing other components. Can exhibit high characteristics in terms of mechanical strength such as tensile strength and bending strength.

  The PBT resin composition of the present invention can be produced by various known molding methods such as injection molding, hollow molding, extrusion molding, compression molding, calendar molding, rotational molding, etc. It is possible to obtain molded articles in fields, medical fields, and the like. A particularly preferable molding method is an injection molding method because of good fluidity, and it is preferable to control the resin temperature to 240 to 280 ° C. in the injection molding.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded. In the examples, “part” represents “part by weight”.

[raw materials]
(A) Polybutylene terephthalate (PBT) resin (A-1) Polybutylene terephthalate resin 1 (PBT1):
Intrinsic viscosity 0.83 dl / g, terminal carboxyl group content 16 eq / ton, temperature drop crystallization temperature 177 ° C., residual THF 180 ppm
(A-2) Polybutylene terephthalate resin 2 (PBT2)
Intrinsic viscosity 0.85 dl / g, terminal carboxyl group amount 35 eq / ton, temperature drop crystallization temperature 176 ° C., residual THF 250 ppm

(B) Thermoplastic elastomer (PTMG copolymer polybutylene terephthalate)
(B-1) Polyester / ether type block copolymer (PTMG content 50) having polybutylene terephthalate as a hard segment and polytetramethylene ether glycol (hereinafter referred to as PTMG) having a weight average molecular weight of 1000 as a soft segment. Wt%, intrinsic viscosity 0.95 dl / g)
(B-2) Polyester-ether type block copolymer having polybutylene terephthalate as a hard segment and polytetramethylene ether glycol having a weight average molecular weight of 1000 as a soft segment (PTMG content 10% by weight, intrinsic viscosity 0. 95dl / g)

(C) Epoxy compound: diglycidyl ether of bisphenol A (Asahi Denka, Adeka Sizer EP-17)
(D) Reinforcing filler: glass fiber (manufactured by Nippon Electric Glass, T-187 fiber diameter 13 μm)

[Production method of PBT resin]
(PBT1)
Both raw materials were supplied to a slurry preparation tank at a ratio of 1.8 mol of 1,4-butanediol to 1.0 mol of terephthalic acid, and 2,976 parts by weight of slurry prepared by mixing with a stirrer (terephthalic acid 9.06 mol parts, 1,4-butanediol 16.31 mol parts) was continuously transferred to the first esterification reactor adjusted to a temperature of 230 ° C. and a pressure of 101 kPa by a gear pump, and tetrabutyl titanate 3 .14 parts by weight was supplied, and the esterification reaction was conducted with stirring for 2 hours to obtain an oligomer.

  The oligomer obtained in the first esterification reaction tank was transferred to a second esterification reaction tank adjusted to a temperature of 240 ° C. and a pressure of 101 kPa, and the esterification reaction was further advanced with stirring for 1 hour. Next, the oligomer obtained in the second esterification reaction tank was transferred to a first polycondensation reaction tank adjusted to a temperature of 250 ° C. and a pressure of 6.67 kPa, and the polycondensation reaction was performed with stirring for 2 hours. A prepolymer was obtained.

  The prepolymer obtained in the first polycondensation reaction tank is transferred to a second double condensation reaction tank adjusted to a temperature of 250 ° C. and a pressure of 133 Pa. The residence time is 3 hours, and the polycondensation reaction is further advanced with stirring. A polymer was obtained. The polymer was extracted from the second double condensation reaction tank, transferred to a die, drawn into a strand, and cut with a pelletizer to obtain a beret-like polybutylene terephthalate resin (PBT1).

(PBT2)
Both raw materials were supplied to a slurry preparation tank at a ratio of 1.8 mol of 1,4-butanediol to 1.0 mol of terephthalic acid, and 2,976 parts by weight of slurry prepared by mixing with a stirrer (terephthalic acid 9.06 mol part, 1,4-butanediol 16.31 mol part) was continuously transferred by a gear pump to the first esterification reaction vessel adjusted to a temperature of 250 ° C. and a pressure of 101 kPa, and tetrabutyl titanate 3 .14 parts by weight was supplied, and the esterification reaction was conducted with stirring for 1 hour to obtain an oligomer.

  The oligomer obtained in the first esterification reaction tank was transferred to a second esterification reaction tank adjusted to a temperature of 260 ° C. and a pressure of 101 kPa, and the esterification reaction was further advanced with stirring at a residence time of 0.5 hour. . Next, the oligomer obtained in the second esterification reaction tank was transferred to the first polycondensation reaction tank adjusted to a temperature of 270 ° C. and a pressure of 6.67 kPa, and the polycondensation reaction was conducted with stirring for 1 hour. A prepolymer was obtained.

  The prepolymer obtained in the first polycondensation reaction tank is transferred to a second double condensation reaction tank adjusted to a temperature of 270 ° C. and a pressure of 133 Pa, and the polycondensation reaction is further advanced with stirring at a residence time of 1.5 hours. To obtain a polymer. The polymer was extracted from the second double condensation reaction tank, transferred to a die, drawn into a strand, and cut with a pelletizer to obtain a beret-like polybutylene terephthalate resin (PBT2).

[Performance evaluation method for molded products]
(1) Tensile test It measured based on ISO527.
(2) Bending test It measured based on ISO178. Here, the value (%) of the bending strain represents the toughness of the molded product, and a high value of (bending strain / flexural modulus) indicates that the molded product is hard (not easily deformed) but has high toughness. It is shown.

(3) Hydrolysis resistance An ISO test piece was wet-heat treated at 121 kPa, saturated steam at 203 kPa for 100 hours, the tensile strength before and after the treatment was measured according to ISO 527, the retention rate was determined according to the following formula, and the hydrolysis resistance was determined. It was.
Strength retention (%) = (Tensile strength after treatment / Tensile strength before treatment) × 100

[Examples 1 and 2, Comparative Examples 1 to 5]
Each component was mixed so that it might become the mixture ratio of Table 1, and each component was melt-kneaded at 260 degreeC using the twin screw extruder with a screw diameter of 30 mm (Nippon Steel Works TEX30C), The PBT resin composition pellets were obtained by extrusion into a strand. Using the obtained pellets, an ISO test piece was molded under the conditions of a cylinder temperature of 250 ° C. and a mold temperature of 80 ° C. using an injection molding machine (model SG-75SYCAP-MIII) manufactured by Sumitomo Heavy Industries, Ltd. Performance evaluation was performed by the above test method. The results are shown in Table 1.

（１）実施例１と比較例２、実施例２と比較例４とをそれぞれ比較すると、（Ａ）末端カルボキシル基量が３０ｅｑ／ｔｏｎ以下のＰＢＴ樹脂を配合する実施例１及び２においては、低温（−４０℃）での曲げ歪み量が高く、且つ曲げ歪み／曲げ弾性率（一般的には数値が高いほど靭性が高いことを示す）も高く、また２３℃の曲げ歪み量に対する保持率も高く、低温においても破損しにくいことを示している。また、同時に実施例1及び２は、良好な耐加水分解性を示しており、自動車向けコネクター用材料としても適していることが分かる。

(1) When Example 1 and Comparative Example 2 are compared with Example 2 and Comparative Example 4, respectively, (A) In Examples 1 and 2 in which a PBT resin having a terminal carboxyl group amount of 30 eq / ton or less is blended, The bending strain at a low temperature (−40 ° C.) is high, the bending strain / flexural modulus (in general, the higher the numerical value, the higher the toughness is), and the retention rate with respect to the bending strain at 23 ° C. It is also high and indicates that it is difficult to break even at low temperatures. At the same time, Examples 1 and 2 show good hydrolysis resistance and are also suitable as automotive connector materials.

(2) When Example 1 and Comparative Example 5 are compared, in Comparative Example 5 in which the (B) polyester-ether type block copolymer of the present invention is not blended, the hydrolysis resistance is equivalent. It can be seen that the material has a small bending strain at 23 ° C. and −40 ° C. and is a brittle material.
Further, when Example 1 and Comparative Example 1 were compared with Example 2 and Comparative Example 3, respectively, the content of PTMG in the polyester / ether block copolymer was within the range of the present invention (25 to 80% by weight). In Examples 1 and 2, the amount of bending strain at a low temperature (−40 ° C.) is high, the bending strain / bending elastic modulus (toughness) is high, and the retention rate against the amount of bending strain at 23 ° C. is also high. It shows that it is hard to break even at low temperatures. At the same time, Examples 1 and 2 show good hydrolysis resistance.

  Therefore, the low-temperature bending properties and hydrolysis resistance achieved in the present invention are (A) the amount of terminal carboxyl groups of the PBT resin, and (B) the content of PTMG in the polyester-ether type block copolymer, It can be seen that this is a synergistic effect by bringing each of these within the scope of the present invention.

(3) Comparing Example 1 and Example 2, by blending (C) an epoxy compound, the amount of bending strain at a low temperature, similar to the components (A) and (B) of the present invention described above, It can be seen that the bending strain / flexural modulus (toughness), the retention with respect to the bending strain at 23 ° C., and the hydrolysis resistance are improved. The effect of the epoxy compound in the present invention is surprising in view of the tendency that the toughness of the molded product tends to decrease because the epoxy compound generally shows a crosslinking property.

Claims (5)

  (A) Containing 25 to 80% by weight of polyalkylene ether glycol having a weight average molecular weight of 400 to 6000 as a structural unit with respect to 100 parts by weight of polybutylene terephthalate resin having a terminal carboxyl group amount of 30 eq / ton or less A polybutylene terephthalate resin composition comprising 1 to 30 parts by weight of a polyester / ether type polyester-based thermoplastic elastomer.   The ratio [η (A) / η (B)] of the intrinsic viscosity of (A) polybutylene terephthalate resin to the intrinsic viscosity of (B) polyester-based thermoplastic elastomer is 0.3 to 3.0. The polybutylene terephthalate resin composition described in 1.   The polybutylene terephthalate resin composition according to claim 1 or 2, wherein 0.05 to 10 parts by weight of (C) an epoxy compound is blended with respect to 100 parts by weight of (A) polybutylene terephthalate resin.   The polybutylene terephthalate resin composition according to any one of claims 1 to 3, wherein (D) the reinforcing filler is blended in an amount of 1 to 140 parts by weight with respect to 100 parts by weight of the (A) polybutylene terephthalate resin.   A molded article obtained by molding the polybutylene terephthalate resin composition according to any one of claims 1 to 4.