TITLE OF THE INVENTION : POLYBUTYLENE TEREPHTHALATE RESIN COMPOS ITION, MOLDED ARTICLE CONTAINING THE SAME, AND LIGHT REFLECTOR

TECHNICAL FIELD

[ 0001 ]

The present invention relates to a polybutylene terephthalate resin composition used in the production of a light reflector, and a molded article obtained by molding the polybutylene terephthalate resin composition . The present invention relates to a molded article or a resin composition that is suitable for use in a reflector including a metallized film provided on a surface of the molded article or the resin composition .

BACKGROUND ART

[ 0002 ]

Conventionally, as for a light reflector of automobile lamps , such as a housing, a reflector, and an extension, and a light reflector of household lighting apparatuses , one obtained by subj ecting a thermosetting resin molded article to metal plating, or vapor-depositing or applying a metal thin film onto a thermosetting resin molded article has been used . The thermosetting resin molded article i s represented by a bulk molding compound (BMC ) , and a sheet molding compound ( SMC ) . The metallic reflector, e . g . a molded metal article ( sheet metal ) , has disadvantages that it i s poor in proces sability, and is heavy and difficult to handle . In contrast , the reflector obtained by sub jecting a thermosetting resin molded article to metal plating, or vapor-depositing a metal thin film onto a thermosetting resin molded article has excellent characteristics including heat resi stance, rigidity, and dimensional stability . However, the reflector has problems such as a lengthy molding cycle, generation of burrs during molding, and volatilization of monomers during molding and the consequent deterioration of the working environment . For this reason, in accordance with functional improvement and diversi fication of designs of such light reflectors , a light reflector has become mainstream, which is free of the above-mentioned problems , and which i s obtained by vapor-depositing a metal thin film onto a thermoplastic resin molded article produced with excellent productivity .

[ 0003 ]

Examples of the method for producing such a light reflector include a method in which, for the purpose of imparting surface smoothnes s to a part serving as a light reflecting surface of a molded article containing a thermoplastic resin composition, the part i s sub jected to a primer treatment (that is , a primer coating film i s formed) to have high smoothness , a metal is vapor-deposited onto the primer coating film, and a top coat i s further applied thereto as neces sary . Due to such a process , the light reflector has optical accuracy ( reflection accuracy) comparable to that in the case of the thermosetting resin . However, the above-mentioned conventional method of subj ecting the molded article to the primer treatment is not environmentally preferable because an organic solvent is used in the primer treatment . Further, the method has poor productivity because it takes time to volatilize the organic solvent and cure the coating film . Moreover, the total cost of the method i s high because high cost i s required for plating and vapor deposition, a larger number of production steps are required, and a decrease in yield i s al so concerned For this reason, there is a demand for a thermoplastic resin composition for a light reflector, which does not require pre-processing and onto which a metal can be directly vapor- deposited .

[ 0004 ]

I f a thermoplastic resin molded body, onto which a metal thin film i s directly vapor-deposited without the need for formation of the primer coating film, comes to have an optical surface comparable to that of a conventional product , it i s possible to obtain an ef fect of improving productivity owing to reduction of steps during the production of a product , and an effect of environmental responsiveness owing to elimination of a primer coating agent .

[ 0005 ]

In addition, since the light reflector i s mainly used as a component for a lamp member, the use environment temperature of the light reflector i s in a range of 100 to 200 ° C . Therefore , there is also a problem that an adhesive gas generated during the use of the light reflector adheres to the lens cover, the mirror, and the like and make them cloudy ( fogging) .

[ 0006 ]

Patent Document 1 proposes a light reflector containing a resin composition that contains a thermoplastic polyester resin and a fatty acid ester blended therewith . Further, Patent Document 2 proposes a thermoplastic resin composition with reduced gas generation, the thermoplastic resin composition containing a thermoplastic resin, and blended therewith a fatty acid ester and a compound having a carboxylic acid group-reactive group and a hydroxyl groupreactive group in one molecule .

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[ 0007 ] Patent Document 1 : Japanese Patent Laid-open

Publication No . 2009-102581

Patent Document 2 : Japanese Patent Laid-open

Publication No . 2009-298827

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[ 0008 ]

As described above, resin material s used in light reflectors are required to be reduced in the amount of gas generated when a molded article has a high temperature ( such properties are called low-fogging properties ) . In recent years , it has al so been studied to increase the degree of freedom in the design of automobile lamps themselves . Usually, in inj ection molding, in order to facilitate the removal of a molded article produced from an inj ected resin from a mold, a molding surface of the mold is given a certain degree of inclination to facilitate pulling out of the molded article . Meanwhile, there i s a demand for a material that facilitates pulling out of the molded article without giving the inclination to the mold . That is , reduction of the draft angle of the mold has been studied . A problem to be solved in order to reali ze the reduction of the draft angle i s to impart characteristics that a resin product is easily released from a mold while maintaining the low-fogging properties and vapor deposition capability .

[ 0009 ]

As described above , a resin material used in a light reflector designed to be produced by a mold with small draft angle is required to have low-fogging properties and releasability . Meanwhile, in the technique described in Patent Document 1 , the surface of the molded article is poor in smoothness due to an inorganic filler blended in the resin composition, and the technique may cause a problem in products that are sub jected to vapor deposition without a primer treatment . Further, in the technique described in Patent Document 2 , although the amount of gas generated is reduced due to the compound having a carboxylic acid groupreactive group and a hydroxyl group-reactive group in one molecule, the resin has high molding shrinkage rate, and has a problem in releasability when being released from the mold . [ 0010 ]

Under such circumstances , an obj ect of the present invention is to solve the above-mentioned problems and provide a polybutylene terephthalate resin composition excellent in releasability while maintaining low-fogging properties , and a light reflector including a molded article containing the polybutylene terephthalate resin composition, and a metalli zed film directly formed on at least a part of a surface of the molded article . SOLUTIONS TO THE PROBLEMS [0011]

In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, have arrived at the present invention. [0012]

That is, the present invention relates to the following.

(1) A polybutylene terephthalate resin composition containing :

(A) 100 parts by weight of a polybutylene terephthalate-based resin containing a butylene isophthalate unit and a butylene terephthalate unit in one molecule or a plurality of molecules thereof; and

(B) 0.2 to 2 parts by weight of a fatty acid ester compound synthesized from a trihydric to hexahydric aliphatic alcohol and a fatty acid, wherein the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof contains, with respect to 100 mol% in total of acid components in the polybutylene terephthalate-based resin (A) , 0.1 to 5.5 mol% of an isophthalic acid component. [0013]

(2) The polybutylene terephthalate resin composition according to the item (1) , wherein the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof is a resin mixture containing (A-l) polybutylene terephthalate and (A- 2) a polybutylene terephthalate copolymer containing isophthalic acid as a copolymerization component, and the polybutylene terephthalate-based resin (A) has a weight ratio of the polybutylene terephthalate (A-l) to the polybutylene terephthalate copolymer (A-2) , that is, ( (A- 1) : (A-2) ) of 99.8 : 0.2 to 1 : 99. [0014]

(3) The polybutylene terephthalate resin composition according to the item (1) or (2) , further containing 0.1 to 2 parts by weight of a colorant (C) with respect to 100 parts by weight of the polybutylene terephthalate-based resin. [0015]

(4) The polybutylene terephthalate resin composition according to any one of the items (1) to (3) , wherein the fatty acid ester compound (B) synthesized from the trihydric to hexahydric aliphatic alcohol and the fatty acid is dipentaerythritol hexastearate.

[0016]

(5) The polybutylene terephthalate resin composition according to any one of the items (1) to (4) , wherein the fatty acid ester compound (B) synthesized from the trihydric to hexahydric aliphatic alcohol and the fatty acid has an acid value of 0.1 to 10 mgKOH/g.

[0017]

(6) The polybutylene terephthalate resin composition according to any one of the items (1) to (5) , the polybutylene terephthalate resin composition satisfying two or more of conditions [1] to [3] described below:

[1] a release force of 400 N or less;

[2] a haze of 5% or less; and

[3] a percent defective in a streak-like appearance defect test of 5% or less.

[0018]

(7) A molded article containing the polybutylene terephthalate resin composition according to any one of the items ( 1 ) to ( 6 ) .

[0019]

(8) A light reflector including: the molded article according to the item (7) ; and a metallized film directly formed on at least a part of a surface of the molded article.

EFFECTS OF THE INVENTION

[0020]

The polybutylene terephthalate resin composition of the present invention has low-fogging properties , and can provide a light reflector excellent in releasability even by a mold with small draft angle .

EMBODIMENTS OF THE INVENTION

[ 0021 ]

Hereinafter, embodiments of the present invention will be described in detail , but the present invention i s not construed as being limited to the following embodiment s at all , and can be implemented with appropriate modifications within the scope of the ob ject of the present invention . [ 0022 ]

The polybutylene terephthalate resin composition of the present invention contains (A) a polybutylene terephthalate-based resin containing a butylene i sophthalate unit and a butylene terephthalate unit in one molecule or a plurality of molecules thereof , and (B ) a fatty acid ester compound synthesized from a trihydric to hexahydric aliphatic alcohol and a fatty acid . [ 0023 ]

The polybutylene terephthalate resin composition of the present invention contains a reaction product obtained from a reaction among individual components that constitute the resin composition . Since the reaction product is produced by a complicated reaction among polymers , there is a circumstance that it is not practical to specify the structure of the reaction product . Thus , in the present invention, the invention may sometimes be specified by the blended components .

[ 0024 ]

[ Component A]

The polybutylene terephthalate-based resin used in the present invention contains the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof . Polybutylene terephthalate is a polymer obtained by a normal polymerization reaction such as a polycondensation reaction from a raw material mainly containing terephthalic acid or an ester-f orming derivative thereof and 1 , 4-butanediol or an ester-f orming derivative thereof . Examples of the ester-f orming derivative of terephthalic acid include lower alkyl esters of terephthalic acid . More specific examples thereof include a methyl ester, an ethyl ester, a propyl ester, and a butyl ester . The polybutylene terephthalate-based resin used in the present invention can take, for example, an aspect of a mixture of polybutylene i sophthalate and polybutylene terephthalate, an aspect of a polybutylene terephthalate-butylene i sophthalate copolymer, and an aspect of a mixture of a polybutylene terephthalate-butylene isophthalate copolymer and polybutylene terephthalate or polybutylene isophthalate. The aspect of a mixture of polybutylene terephthalate and a polybutylene terephthalatebutylene isophthalate copolymer is advantageous in that the content of the isophthalic acid unit can be easily adjusted. That is, aspects of the polybutylene terephthalate-based resin used in the present invention include, in addition to an aspect in which the polybutylene terephthalate-based resin is a resin having a single composition, an aspect in which the polybutylene terephthalate-based resin is a mixture of a plurality of resins.

[0025]

The polybutylene terephthalate (A-l) used in the present invention preferably has a melt flow rate (hereinafter sometimes abbreviated as "MFR") under the conditions of 250°C and 1 kgf of 5 to 80 g/10 min. When the MFR is 5 g/10 min or more, the fluidity can be further improved. The MFR is more preferably 8 g/10 min or more. Meanwhile, when the MFR is 80 g/10 min or less, a molded article excellent in mechanical properties can be obtained. The MFR is preferably 70 g/10 min or less, and more preferably 60 g/10 min or less. The MFR in the present invention is a value measured in accordance with ISO 1133. [0026]

The method for producing the polybutylene terephthalate (A-l) used in the present invention is not particularly limited, and a known polycondensation method, ring-opening polymerization method, or the like can be used . Either of a batch polymeri zation method and a continuous polymerization method may be used, and either of a method of obtaining polybutylene terephthalate by a transesteri fication reaction and a polycondensation reaction, and a direct polymeri zation method of obtaining polybutylene terephthalate by an esterification reaction and a polycondensation reaction can be applied . The continuous polymerization method i s preferable from the viewpoint that the amount of carboxy end groups can be reduced and the ef fect of improving the fluidity is increased, and the direct polymerization method is preferable from the viewpoint of cost .

[ 0027 ]

In order to effectively advance the esteri fication reaction or transesteri fication reaction and the polycondensation reaction, it i s preferable to add a catalyst during these reactions . Specific examples of the catalyst include an organotitanium compound, a tin compound, a zirconia compound, and an antimony compound . [ 0028 ]

More specific examples of the organotitanium compound include a methyl ester, a tetra-n-propyl ester, a tetra-n- butyl ester, a tetraisopropyl ester, a tetraisobutyl ester, a tetra-tert-butyl ester, a cyclohexyl ester, a phenyl ester, a benzyl ester, and a tolyl ester of titanic acid, and a mixed ester thereof .

[ 0029 ]

More speci fic examples of the tin compound include dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethylditin oxide, cyclohexahexylditin oxide , didodecyltin oxide, triethyltin hydroxide , triphenyltin hydroxide , triisobutyltin acetate , dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, and alkylstannonic acids such as methyl stannonic acid, ethylstannonic acid, and butylstannonic acid . [ 0030 ]

More speci fic examples of the zirconia compound include zirconia compounds such as z irconium tetra-n- butoxide . [ 0031 ]

More speci fic examples of the antimony compound include antimony trioxide and antimony acetate . [ 0032 ]

Among them, an organotitanium compound and a tin compound are preferable from the viewpoint of the catalytic ef fect , a tetra-n-propyl ester, a tetra-n-butyl ester, and a tetraisopropyl ester of titanic acid are preferable from the viewpoint of a higher catalytic effect, and a tetra-n- butyl ester of titanic acid is particularly preferable. Two or more of these catalysts may be used in combination.

[0033]

The amount of the catalyst added is preferably in a range of 0.005 to 0.5 parts by weight, and more preferably in a range of 0.010 to 0.2 parts by weight with respect to 100 parts by weight of the polybutylene terephthalate (A-l) . [0034]

The polybutylene terephthalate copolymer (A-2) containing isophthalic acid as a copolymerization component (hereinafter, the copolymer is sometimes referred to as " (A- 2) isophthalic acid-copolymerized polybutylene terephthalate") used in the present invention is a polymer obtained by copolymerizing terephthalic acid (or an ester- forming derivative thereof such as dimethyl terephthalate) , 1 , 4-butanediol (or an ester-f orming derivative thereof) , and further isophthalic acid (or an ester-f orming derivative thereof) . When isophthalic acid is copolymerized with polybutylene terephthalate, particularly the crystallization speed can be reduced, the shrinkage rate can be reduced, and the resin composition can exhibit good releasability. In addition, the isophthalic acid-copolymerized polybutylene terephthalate also exerts an effect of reducing volatilization of the generated gas , and an ef fect of reducing fogging .

[ 0035 ]

In addition, the polybutylene terephthalate-based resin (A) used in the present invention, which contains the butylene isophthalate unit in one molecule or a plurality of molecules thereof and the butylene terephthalate unit , may contain a repeating unit other than the butylene i sophthalate unit and the butylene terephthalate unit . Examples of a dicarboxylic acid that can be used in such a repeating unit include aromatic dicarboxylic acids such as dodecanedioic acid, phthalic acid, 2 , 6-naphthalenedicarboxylic acid, 1 , 5- naphthalenedicarboxylic acid, bi s (p-carboxyphenyl ) methane, anthracenedicarboxylic acid, 4 , 4 ' -diphenyl ether dicarboxylic acid, and 5-sodium sul foisophthalic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid, and alicyclic dicarboxylic acids such as 1 , 3-cyclohexanedicarboxylic acid and 1 , 4- cyclohexanedicarboxylic acid . [ 0036 ]

In addition, another copolymerizable dicarboxylic acid (or an ester-f orming derivative thereof ) or another diol ( or an ester-f orming derivative thereof ) may be copolymeri zed as long as the characteristics thereof are not impaired . [ 0037 ] In the present invention, the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof contains , with respect to 100 mol% in total of acid component s in the polybutylene terephthalate-based resin (A) , 0 . 1 to 5 . 5 mol% of an isophthalic acid component . That i s , the content of the isophthalic acid component i s determined by determining the total number of moles of a dicarboxylic acid component contained in the polybutylene terephthalate-based resin, and determining the content of the isophthalic acid component in the dicarboxylic acid component as a mole fraction . Herein, the term "component" means a structure derived from a dicarboxylic acid . [ 0038 ]

The polybutylene terephthalate-based resin (A) used in the present invention, which contains the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof , may preferably be a mixture of the polybutylene terephthalate (A-l ) and the polybutylene terephthalate (A-2 ) containing isophthalic acid as a copolymerization component . In thi s case, the content of the isophthalic acid component , with respect to 100 mol% in total of the amount of the dicarboxylic acid component in the polybutylene terephthalate (A-l ) and the amount of a dicarboxylic acid in the polybutylene terephthalate copolymer (A-2) containing isophthalic acid as a copolymerization component, is in a range of 0.1 to 5.5 mol%. When the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof is a mixture of the polybutylene terephthalate (A-l) and the polybutylene terephthalate (A- 2) containing isophthalic acid as a copolymerization component, and the amount of the isophthalic acid component is 0.1 mol% or more, releasability is further improved. When the amount of the isophthalic acid component is 5.5 mol% or less, it is possible to obtain a significant effect of reducing fogging. In this case, the amount of a terephthalic acid component is preferably 80 mol% or more, more preferably 90 mol% or more, and particularly preferably an amount at which the sum of the amount of the terephthalic acid component and the amount of the isophthalic acid component is 100 mol%.

[0039]

It is also possible to set the copolymerization rate of isophthalic acid in the isophthalic acid-copolymerized polybutylene terephthalate (A-2) in a range of 0.1 to 5.5 mol% . However, from the viewpoint of productivity of the isophthalic acid-copolymerized polybutylene terephthalate (A-2) itself, it is preferable to use the polybutylene terephthalate (A-l) and the isophthalic acid-copolymerized polybutylene terephthalate (A-2) in combination. The copolymerization rate of isophthalic acid in the isophthalic acid-copolymerized polybutylene terephthalate (A-2) is preferably in a range of 3 to 30 mol%, and more preferably in a range of 6 to 15 mol% with respect to the dicarboxylic acid component that constitutes the isophthalic acid- copolymerized polybutylene terephthalate (A-2) . [0040]

The viscosity of the isophthalic acid-copolymerized polybutylene terephthalate (A-2) is not particularly limited as long as the resin can be melt-kneaded, but the isophthalic acid-copolymerized polybutylene terephthalate (A-2) preferably has a relative viscosity measured at 25°C using an 8% o-chlorophenol solution of 20 to 40 dl/g. [0041]

In the case where the polybutylene terephthalate-based resin is a mixture of the polybutylene terephthalate (A-l) and the isophthalic acid copolymerized polybutylene terephthalate (A-2) , the weight ratio ( (A-l) : (A-2) ) is preferably 99.8 : 0.2 to 1 : 99. The content of the isophthalic acid component is preferably adjusted in a range of 0.1 to 5.5 mol% with respect to 100 mol% in total of acid components in the polybutylene terephthalate (A-l) and the isophthalic acid-copolymerized polybutylene terephthalate (A-2) .

[0042]

When the copolymerization rate of isophthalic acid in the isophthalic acid-copolymerized polybutylene terephthalate (A-2) is in a range of 6 to 15 mol% as described above, it is preferable to blend the component (A-l) in an amount of 99.4 to 50 parts by weight and the component (A- 2) in an amount of 0.6 to 50 parts by weight with respect to 100 parts by weight in total of the component (A-l) and the component (A-2) . [0043]

[Component B]

The fatty acid ester compound (B) synthesized from the trihydric to hexahydric aliphatic alcohol and the fatty acid (hereinafter, the compound is sometimes simply referred to as " (B) a fatty acid ester compound") used in the present invention is made up of the trihydric to hexahydric aliphatic alcohol and the fatty acid. [0044]

Examples of the trihydric to hexahydric aliphatic alcohol include glycerol, diglycerol, erythritol, pentaerythritol, sorbitol, triglycerol, dipentaerythritol, and tetraglycerol. These aliphatic alcohols may be used alone or in combination of two or more. Preferable aliphatic alcohols are pentahydric or hexahydric aliphatic alcohols such as triglycerol, dipentaerythritol, and tetraglycerol, and dipentaerythritol is particularly preferable. [0045]

The fatty acid is preferably a linear or branched saturated fatty acid having 5 or more and 30 or less carbon atoms. For example, pentanoic acid, hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, and melissic acid are preferable, and stearic acid is particularly preferable. [0046]

In order to avoid a transesterification reaction with the polybutylene terephthalate (A-l) and the isophthalic acid-copolymerized polybutylene terephthalate (A-2) , the fatty acid ester compound (B) is preferably a full ester substantially not containing a free hydroxyl group or a free carboxyl group. Specifically, glycerol tristearate, pentaerythritol tetrastearate, and dipentaerythritol hexastearate are preferable, and dipentaerythritol hexastearate is particularly preferable. [0047]

From the viewpoint of inhibiting the hydrolysis of the polybutylene terephthalate (A-l) and the isophthalic acid- copolymerized polybutylene terephthalate (A-2) , the fatty acid ester compound (B) preferably has an acid value of 0.1 to 10 mgKOH/g, more preferably 0.1 to 5 mgKOH/g, and still more preferably 0.1 to 3 mgKOH/g.

[0048]

The fatty acid ester compound (B) may be used alone or in combination of two or more.

[0049]

The fatty acid ester compound (B) is available, for example, under the trade name of "LOXIOL" (registered trademark) from Emery Oleochemicals Japan Ltd. , "ADK CIZER" (registered trademark) from ADEKA Corporation, and "Rikester" (registered trademark) from RIKEN VITAMIN CO., LTD.

[0050]

In the polybutylene terephthalate resin composition of the present invention, the content of the fatty acid ester compound (B) is 0.2 to 2 parts by weight with respect to 100 parts by weight of the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof. The content of the fatty acid ester compound (B) is preferably 0.2 to 1 part by weight. A blending amount of the fatty acid ester compound (B) less than 0.2 parts by weight or more than 2 parts by weight is not preferable. This is because if the blending amount of the fatty acid ester compound (B) is less than 0.2 parts by weight, the polybutylene terephthalate resin composition is deteriorated in the releasability, and if the blending amount of the fatty acid ester compound (B) is more than 2 parts by weight, the polybutylene terephthalate resin composition is deteriorated in the fogging properties .

[0051]

When the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof is a mixture of the polybutylene terephthalate (A-l) and the isophthalic acid copolymerized polybutylene terephthalate (A-2) , it is also preferable that the content of the fatty acid ester compound (B) be 0.2 to 2 parts by weight, and preferably 0.2 to 1 part by weight with respect to 100 parts by weight in total of the polybutylene terephthalate (A-l) and the isophthalic acid copolymerized polybutylene terephthalate (A-2) . A blending amount of the fatty acid ester compound (B) less than 0.2 parts by weight or more than 2 parts by weight is not preferable. This is because if the blending amount of the fatty acid ester compound (B) is less than 0.2 parts by weight, the polybutylene terephthalate resin composition is deteriorated in the releasability, and if the blending amount of the fatty acid ester compound (B) is more than 2 parts by weight , the polybutylene terephthalate resin composition is deteriorated in the fogging properties .

[ 0052 ]

As for the resin composition of the present invention, combination use of the i sophthalic acid-copolymerized polybutylene terephthalate (A-2 ) and the fatty acid ester compound (B ) provides a resin composition having good fogging properties while maintaining releasability . The reason why the combined use of the isophthalic acid-copolymerized polybutylene terephthalate (A-2 ) and the fatty acid ester compound (B) exhibits such an effect is not clear . However, it i s considered that when the two components coexist , deposition of a decomposition product of the fatty acid ester compound (B ) , which may cause a gas , on the surface of the resin composition is inhibited, and compatibility of contradictory characteristics , that is , being excellent in fogging properties while maintaining releasability can be achieved .

[ 0053 ]

[ Component C ]

The resin composition of the present invention may contain the colorant (C ) . Examples of the colorant ( C ) include inorganic pigments , organic pigments , and organic dyes . Examples of the inorganic pigment include carbon black, sulfide pigments such as cadmium red, and cadmium yellow; silicate pigment s such as ultramarine blue; oxide pigments such as z inc flower, red iron oxide, chromium oxide , titanium oxide, iron black, titanium yellow, zinc-iron brown, titanium-cobalt green, cobalt green, cobalt blue , copperchromium black, and copper-iron black; chromate pigment s such as yellow lead and molybdate orange ; and ferrocyanide pigments such as Prussian blue . Examples of the organic pigment and the organic dye include phthalocyanine dyes and pigments such as copper phthalocyanine blue and copper phthalocyanine green; azo dyes and pigment s such as nickel azo yellow; fused polycyclic dyes and pigment s such as thioindigo, perinone, perylene , quinacridone, dioxaz ine, isoindolinone , and quinophthalone dyes and pigments ; and anthraquinone , heterocyclic, and methyl dyes and pigment s . Two or more of these may be used in combination . Among them, carbon black, titanium oxide, and cyanine , quinoline, anthraquinone , and phthalocyanine compounds are preferable from the viewpoint of thermal stability .

[ 0054 ]

In addition, from the viewpoint that the di spersibility of the colorant in the resin composition is improved, it is preferable to use a masterbatch when adding the colorant . [ 0055 ]

In the present invention, the content of the colorant (C) is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the polybutylene terephthalate-based resin (A) containing the butylene isophthalate unit and the butylene terephthalate unit in one molecule or a plurality of molecules thereof, and is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight in total of the polybutylene terephthalate (A-l) and the isophthalic acid- copolymerized polybutylene terephthalate (A-2) . The content of the colorant (C) is more preferably 0.1 to 1 part by weight. A content of the colorant (C) of 0.1 parts by weight or more and 2 parts by weight or less is preferable. This is because when the content of the colorant (C) is 0.1 parts by weight or more, sufficient coloring is achieved, and when the content is 2 parts by weight or less, impact resistance can be maintained.

[0056]

[Other components]

In the polybutylene terephthalate resin composition of the present invention, as a resin component not containing a butylene isophthalate unit or a butylene terephthalate unit, a resin component such as a polyester resin including polyethylene terephthalate, and an acrylonitrile-styrene copolymer or a modified copolymer thereof, as well as other normal additives such as a release agent, a stabilizer, and a lubricant can be blended as long as the effects of the present invention are not impaired. Two or more of such components may be blended.

[0057]

[Production method]

In the polybutylene terephthalate resin composition of the present invention, the components (A) and (B) , the component (C) blended as necessary, and other components are preferably uniformly dispersed.

[0058]

Examples of the method for producing the polybutylene terephthalate resin composition of the present invention include a method in which the components are individually melt-kneaded using a known melt-kneading machine such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, or a mixing roll. The components may be mixed together in advance and then melt-kneaded. The amount of moisture contained in the individual components is preferably small, and it is desirable to dry the components in advance as necessary.

[0059]

Examples of the method of introducing the components into the melt-kneading machine include a method in which a single-screw or twin-screw extruder is used, and the components (A) and (B) are supplied from a feeder to a main inlet installed at the root of the screw, the component (C) is supplied from an independent dedicated feeder to the main inlet or a sub inlet positioned between the main inlet and the tip of the extruder, and the components are melt-mixed. [0060]

The melt-kneading temperature is preferably 110 °C or more, more preferably 210°C or more, and still more preferably 240°C or more from the viewpoint of excellent fluidity and mechanical properties. The melt-kneading temperature is preferably 360°C or less, more preferably 320°C or less, and still more preferably 280°C or less. Herein, the melt-kneading temperature refers to the setting temperature of the melt-kneading machine. For example, in the case of a twin-screw extruder, the melt-kneading temperature refers to a cylinder temperature. [0061]

[Molded body]

The polybutylene terephthalate resin composition of the present invention can be molded by an arbitrary method such as known injection molding, extrusion molding, blow molding, press molding, or spinning to be processed into various molded bodies and used. Among them, the injection molding method is preferable from the viewpoint of versatility .

[0062]

The temperature during injection molding is preferably 240°C or more from the viewpoint of further improving fluidity, and is preferably 280°C or less from the viewpoint of improving mechanical properties.

[0063]

As for the mold, the abrasive grain size may be set to 5,000 (#5,000) or more, preferably #10,000 or more, or the mold may be subjected to a surface treatment such as chromium plating, so that the molded body may have increased surface smoothness and glossiness, and may easily have a good appearance after coloring or coating. Further, when the molded body is subjected to vapor deposition in the production of a light reflector described later, a light reflector having a good appearance is easily obtained. [0064]

The mold releasability can be evaluated, for example, by measuring the ejection force (release force) when a light reflector component is released from the mold. The smaller the release force is, the better the mold releasability is. The release force is not particularly limited. However, when the release force is, for example, 1,000 N or less, the light reflector component exhibits good mold releasability when being molded, and cracks and rubbing at the time of mold release tend to be further reduced, so that productivity of a large light reflector component having a complicated shape can be improved. [ 0065 ]

[ Light reflector ]

The light reflector of the present invention includes the light reflector component containing the resin composition of the present invention, and a light-reflecting metal layer directly formed on at least a part of a surface of the light reflector component . The method for directly forming the light-reflecting metal layer on the light reflector component is not particularly limited, and a known method such as vapor deposition can be used . Examples of the metal for forming the light-reflecting metal layer include aluminum, chromium, nickel , and titanium . Among them, aluminum is preferable from the viewpoint of influence on the environment and economy .

[ 0066 ]

Examples of the light reflector obtained in thi s manner include light reflectors ( such as a housing, a reflector, and an extension) of automobile lamps ( such as a headlight and a turn-signal lamp of automobiles ) , and light reflectors ( such as a lamp case ) of lamps for home appliances .

EXAMPLES

[ 0067 ]

Hereinafter, the present invention will be described more specifically with reference to examples , but the present invention is not limited to these examples. Raw materials used in the examples and comparative examples are shown below. [0068]

(A-l) Polybutylene terephthalate

Polybutylene terephthalate (MFR: 35 g/10 min (250°C, 1 kgf ) ) [0069]

(A-2) Isophthalic acid-copolymerized polybutylene terephthalate

Into a reaction can equipped with a rectification column and a stirrer, 65.6 parts by weight of terephthalic acid, 7.3 parts by weight of isophthalic acid, 61.4 parts by weight of 1 , 4-butanediol , 0.05 parts by weight of tetrabutyl titanate as a catalyst, and 0.04 parts by weight of monobutyltin oxide were charged, and the temperature was raised from 150°C to 235°C over 4 hours under normal pressure to perform an esterification reaction. The generated water and tetrahydrofuran were distilled off through the rectification column to give a tetrahydrof uran-containing product. Then, 0.02 parts by weight of phosphoric acid as a coloring inhibitor and 0.05 parts by weight of tetrabutyl titanate as a polycondensation catalyst were added to the resulting esterification reaction product, and then the mixture was transferred to a polycondensation reaction can. The pressure was gradually reduced from normal pressure to 67 Pa over 50 minutes, and the temperature was raised to 245°C at the same time, and a polycondensation reaction was performed for 2 hours and 50 minutes to give a 10 mol% isophthalic acid-copolymerized polybutylene terephthalate copolymer. The obtained polybutylene terephthalate copolymer had a relative viscosity of 26 dl/g.

[0070]

(A-3) Dodecanedioic acid-copolymerized polybutylene terephthalate

Into a reaction can equipped with a rectification column and a stirrer, 65.6 parts by weight of terephthalic acid, 13.6 parts by weight of dodecanedioic acid, 61.4 parts by weight of 1 , 4-butanediol , 0.05 parts by weight of tetrabutyl titanate as a catalyst, and 0.04 parts by weight of monobutyltin oxide were charged, and the temperature was raised from 150°C to 235°C over 4 hours under normal pressure to perform an esterification reaction. The generated water and tetrahydrofuran were distilled off through the rectification column to give a tetrahydrof uran-containing product. Then, 0.02 parts by weight of phosphoric acid as a coloring inhibitor and 0.05 parts by weight of tetrabutyl titanate as a polycondensation catalyst were added to the resulting esterification reaction product, and then the mixture was transferred to a polycondensation reaction can. The pressure was gradually reduced from normal pressure to 67 Pa over 50 minutes, and the temperature was raised to 245°C at the same time, and a polycondensation reaction was performed for 2 hours and 50 minutes to give 13 mol% dodecanedioic acid-copolymerized polybutylene terephthalate The obtained dodecanedioic acid-copolymerized polybutylene terephthalate had a relative viscosity of 32 dl/g.

[0071]

(B) Fatty acid ester compound

B-l: dipentaerythritol hexastearate ("LOXIOL"

(registered trademark) VPG 2571 (trade name) manufactured by Emery Oleochemicals Japan Ltd., acid value: 1.2 mgKOH/g) [0072]

(C) Colorant

C-l: a masterbatch of 40 mass% of carbon black and 60 mass% of (A-l) polybutylene terephthalate (P500B3 (trade name) manufactured by ECCA CO., LTD. ) [0073]

Evaluation methods in the examples and comparative examples will be described. The number n of evaluations was set to n = 3 unless otherwise specified, and the average thereof was obtained.

[0074]

(1) Low-fogging properties (haze)

A resin composition having the composition shown in each of the examples and comparative examples was injection- molded to produce a rectangular plate molded article having a length of 80 mm, a width of 80 mm, and a thickness of 2 mm. From each of these molded articles, 2 g of a molded piece was cut out and put in a glass tube (inner diameter: 15 mm, height: 74 mm, hole diameter: 10 mm) . A 25-mm portion of the glass tube was placed in a metal bath, the top of the glass tube was covered with a glass plate, and the glass tube was treated at 160°C for 20 hours. Then, a portion of the glass plate to be tested was subjected to a measurement with a haze meter. When the haze value is 5% or less, it can be determined that the resin composition has good low- fogging properties .

[0075]

(2) Releasability (release force and cracks of molded article)

A resin composition having the composition shown in each of the examples and comparative examples was injection- molded to produce a hollow cylindrical molded article having a diameter of 70 mm, a depth of 20 mm, and a thickness of 2 mm. The hollow cylindrical molded article was ejected by an ejector pin, and the resistance then was measured as a release force. When the release force is 500 N or less, it can be determined that the resin composition has good releasability. In addition, a case where the molded article could not be released due to high release resistance even when the molded article was tried to be ejected by the ejector pin was determined as "fail". Moreover, the released molded articles were visually observed, and the molded article having no cracks was evaluated as "o", and the molded article having cracks was evaluated as "x" .

[0076]

(3) Appearance test (streak-like appearance defect test )

A resin composition having the composition shown in each of the examples and comparative examples was injection- molded using a mold polished with abrasive grains having a size of 14,000 to produce a mirror-finished rectangular plate molded article having a length of 100 mm, a width of 70 mm, and a thickness of 3 mm. Whether or not the resulting molded article had an appearance defect was examined. A molded article with a streak-like pattern visually observed on the surface was determined as having an appearance defect . The injection conditions were a cylinder temperature of 260°C, a mold temperature of 40°C, an injection pressure of 40 MPa, an injection speed of 20 mm/sec, an injection time of 10 seconds, and a cooling time of 5 seconds. Each of the resin compositions was subjected to 20 shots of molding, and the percent defective in 20 molded articles was determined (percent defective (%) = number of defects/20 x 100) . When the percent defective is 5% or less, it can be determined that the molded articles have a good appearance. [0077]

[Examples 1 to 8]

Using resin compositions having various formulations as shown in Table 1, the components (A-l) , (A-2) , and (B) were supplied from a main inlet of a twin-screw extruder, and the component (C) was supplied from a sub inlet positioned between the main inlet and the tip of the extruder, and the components were melt-kneaded with the twin-screw extruder (TEX30a manufactured by The Japan Steel Works, Ltd. ) having a screw diameter of 30 mmcp and having a cylinder temperature set at 260°C. [0078]

A strand discharged from the die was cooled in a cooling bath, and then pelletized by a strand cutter. Each of the obtained pellets was dried in a hot air dryer at 130°C for 3 hours or more, then a test piece was produced, and the test piece was subjected to the evaluations of fogging properties, releasability, and appearance by the above- mentioned evaluation methods. All of the obtained test pieces were excellent in fogging properties, releasability, and appearance. [0079]

[Comparative Examples 1 to 6]

Using resin compositions having various formulations as shown in Table 1, the components (A-l) , (A-2) , and (B) were supplied from a main inlet of a twin-screw extruder, and the component (C) was supplied from a sub inlet positioned between the main inlet and the tip of the extruder, and the components were melt-kneaded with the twin-screw extruder (TEX30a manufactured by The Japan Steel Works, Ltd. ) having a screw diameter of 30 mmcp and having a cylinder temperature set at 260°C. [0080]

A strand discharged from the die was cooled in a cooling bath, and then pelletized by a strand cutter. Each of the obtained pellets was dried in a hot air dryer at 130°C for 3 hours or more, then a test piece was produced, and the test piece was subjected to the evaluations of fogging properties, releasability, and appearance by the above- mentioned evaluation methods. The obtained test pieces were poor in any of fogging properties, releasability, and appearance . [0081] [Table 1-1]

[Table 1-2]

INDUSTRIAL APPLICABILITY

[0082]

The polybutylene terephthalate resin composition of the present invention can provide a molded article having good fluidity, fogging properties, and mold releasability. In particular, the polybutylene terephthalate resin composition of the present invention is suitable as a material for a light reflector of automobile lamps , for example, a housing, a reflector, and an extension, as well as a light reflector that constitutes a light reflector of lighting apparatuses .