Polyester resin composition, light reflector component containing the polyester resin composition, and light reflector

Abstract

A polyester resin composition exhibits high heat resistance, low gas content, and the ability to significantly suppress mold contamination during continuous molding and to inhibit flow marks. The polyester resin composition comprises: a polyester resin A containing 82-88% by mass of polybutylene terephthalate resin and 12-18% by mass of polyethylene terephthalate resin; an organometallic acid salt B, selected from one or both of alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts; 1-13 parts by mass of an inorganic filler C with an average particle size of 0.05-3 μm relative to 100 parts by mass of the polyester resin A; and 0.000005-0.05 parts by mass of one or both of alkali metal atoms and alkaline earth metal atoms relative to 100 parts by mass of the polyester resin A; and the content of linear oligomers such as polybutylene terephthalate is less than 1000 mg / kg.

Description

Technical Field

[0001] The present invention relates to polyester resin compositions, light reflector components containing the polyester resin compositions, and light reflectors. Background Technology

[0002] In applications such as automotive lamps and other lighting equipment that require high brightness (smoothness) and uniform reflectivity, as well as light reflector components with a light reflective layer on the surface, heat-resistant reinforcing resins are widely used by adding polyethylene terephthalate resin and inorganic fillers such as talc and mica to polybutylene terephthalate resin. However, in lamp components known as extensions, sufficient light-concentrating and reflective effects cannot be obtained without primer treatment on the surface of such reinforcing resin and an aluminum vapor deposition process.

[0003] In recent years, although polybutylene terephthalate (PET) resins or polycarbonate resins, which offer excellent surface smoothness and eliminate the need for a primer treatment, have been frequently used, their heat resistance is sometimes insufficient. Furthermore, due to the high shrinkage rate of PET, mold release properties can be significantly compromised when the molded part has a complex shape, limiting the design possibilities. On the other hand, adding polyethylene terephthalate (PET) resin or a small amount of inorganic filler to PET resin offers advantages such as eliminating the need for a primer treatment, providing excellent smoothness, suppressing shrinkage, and exhibiting superior heat resistance.

[0004] One proposed resin composition is a polybutylene terephthalate resin with added polyethylene terephthalate resin and a small amount of inorganic filler, as described above. In addition to smoothness and heat resistance, it also has good appearance, fogging resistance and low mold contamination.

[0005] Patent Document 1 proposes a polyester resin composition with good heat resistance achieved through a primerless treatment process by mixing it with polybutylene terephthalate resin particles and polyester resin powder, using specific inorganic filler with varying average particle size and addition amount. Patent Document 2 proposes a polyester resin composition with good heat resistance, minimal problems (orange peel defects, whitening) on ​​metal vapor-deposited layers, and good appearance, achieved by adding polyethylene terephthalate resin and barium sulfate with an average particle size of less than 1 μm to polybutylene terephthalate resin. Patent Document 3 proposes a resin composition with good fogging resistance and good surface smoothness, achieved by adding polyethylene terephthalate resin, spherical inorganic filler with an average particle size of less than 1.5 μm, and fatty acid metal salt to polybutylene terephthalate resin. Patent document 4 proposes a polyester resin composition that has low gasity and high heat resistance, and can significantly suppress mold stains during continuous molding, by adding polyethylene terephthalate resin and inorganic fillers with an average particle size of 0.05 to 0.3 μm to polyethylene terephthalate resin, and adding spherical inorganic fillers with an average particle size of 1.5 μm and organometallic acid salts to polyethylene terephthalate resin.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5864021

[0009] Patent Document 2: Japanese Patent No. 5284557

[0010] Patent Document 3: Japanese Patent No. 5292877

[0011] Patent Document 4: Japanese Patent Application Publication No. 2017-48374 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] In recent years, with the development of mold technology, the improvement of the appearance of molded products, and the increase in the required mirror polishing level of molds, a problem has arisen when using polybutylene terephthalate (PET) and polyethylene terephthalate (PET) in combination: tree ring-like patterns (hereinafter referred to as "flow marks") often appear at places where the injection speed drops sharply, such as at the flow ends and flow junctions, and at areas with changes in thickness. These flow marks can be slightly improved by adjusting the injection speed and mold temperature, but sometimes not sufficiently, and undesirable appearances may also occur. Since traditional technologies cannot solve this new problem, there is a market demand for a thermoplastic polyester resin composition with the lowest possible injection speed that is also less prone to flow marks.

[0014] In order to suppress the formation of flow marks, the inventors conducted in-depth research and discovered that by controlling the amount of polyethylene terephthalate resin added to polybutylene terephthalate resin within a specific range, a polyester resin composition with low gas content, high heat resistance, good surface smoothness, and suppressed flow mark formation can be obtained, thus completing the present invention.

[0015] That is, the object of the present invention is to provide a polyester resin composition having low gasity and high heat resistance, good surface smoothness, and the ability to suppress the generation of flow marks; a light reflector component and a light reflector containing the polyester resin composition.

[0016] Methods for solving problems

[0017] That is, the present invention is as follows.

[0018] [1] A polyester resin composition comprising polyester resin A, wherein the polyester resin A contains 82-88% by weight of polybutylene terephthalate resin and 12-18% by weight of polyethylene terephthalate resin; the polyester resin composition comprises an organometallic acid salt B of any one or both of alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts, and 1-13 parts by weight of inorganic filler C with an average particle size of 0.05-3 μm relative to 100 parts by weight of the polyester resin A; the polyester resin composition comprises 0.000005-0.05 parts by weight of alkali metal organometallic acid salt relative to 100 parts by weight of the polyester resin A. The polyester resin composition contains either or both of the following: metal atoms and alkaline earth metal atoms; the content of polybutylene terephthalate linear oligomer, or the content of polybutylene terephthalate linear oligomer and polyethylene terephthalate linear oligomer, is below 1000 mg / kg; and the maximum height roughness (Rz) of a 100 mm × 100 mm × 2 mm flat plate obtained by injection molding the polyester resin composition at a molding temperature of 260 °C, a mold temperature of 45 °C, and a filling time of 4.5 seconds or more using a mirror-finished mold polished with #16000 abrasive is below 0.70 μm.

[0019] [2] According to the polyester resin composition of [1], wherein, relative to 100 parts by mass of the polyester resin A, the polyester resin composition comprises 0.0005 to 0.05 parts by mass of either or both of the alkali metal atoms and the alkaline earth metal atoms.

[0020] [3] The polyester resin composition according to [1] or [2], wherein the metal of the organometallic acid salt B is one or more metals selected from the group consisting of lithium, sodium, potassium, calcium and magnesium.

[0021] [4] The polyester resin composition according to any one of [1] to [3], wherein the organometallic acid salt B is one or more selected from the group consisting of lithium acetate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, lithium benzoate, sodium benzoate and potassium benzoate.

[0022] [5] The polyester resin composition according to any one of [1] to [4], wherein the inorganic filler C is one or more selected from the group consisting of calcium carbonate, silicon dioxide, kaolin and barium sulfate.

[0023] [6] A component for a light reflector comprising any one of the polyester resin compositions described in [1] to [5].

[0024] [7] A light reflector having a light-reflecting metal layer formed on at least a portion of the surface of the light reflector component described in [6].

[0025] Invention Effects

[0026] According to the present invention, a polyester resin composition having low gasity, high heat resistance, good surface smoothness, and the ability to suppress flow marks can be provided. Detailed Implementation

[0027] The present invention will now be described in detail.

[0028] [Polyester Resin Composition]

[0029] This invention relates to a polyester resin composition comprising polyester resin A, wherein polyester resin A contains 82-88% by mass (more than 82% by mass and less than 88% by mass; in this specification, when a numerical range is indicated by "~", the range includes both the upper and lower limits) of polybutylene terephthalate resin and 12-18% by mass of polyethylene terephthalate resin. The polyester resin composition comprises an organometallic acid salt B, selected from alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts, and 1-13 parts by mass of inorganic filler C with an average particle size of 0.05-3 μm relative to 100 parts by mass of polyester resin A. Further, relative to 100 parts by mass of polyester resin A, the polyester resin composition comprises 0.000005-0.05 parts by mass of alkali metal atoms and alkaline earth metal atoms, selected from both. Furthermore, the content of polybutylene terephthalate linear oligomers, or the content of polybutylene terephthalate linear oligomers and polyethylene terephthalate linear oligomers in the polyester resin composition is less than 1000 mg / kg.

[0030] The polyester resin composition of the present invention contains an organometallic acid salt B, which can suppress the generation of degassing [tetrahydrofuran (hereinafter also referred to as "THF"), etc.] during molding, and suppress the cyclic and linear oligomers contained in the composition from being transported to the mold by THF and then adhering, thereby suppressing mold stains based on these oligomers.

[0031] Furthermore, the polyester resin composition may contain the mold release agent D described later. Furthermore, without impairing the effects of the present invention, the polyester resin composition may contain various additives as needed. Examples of additives include modifiers, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, modifiers, antistatic agents, flame retardants, dyes, pigments, etc. The total content of polyester resin A, organometallic acid salt B, inorganic filler C, and mold release agent D (but the addition of mold release agent D is optional) in the polyester resin composition of the present invention preferably accounts for 85% or more by mass, more preferably 90% or more by mass, and even more preferably 95% or more by mass.

[0032] Furthermore, the polyester resin composition of the present invention has low gas content and high heat resistance, good surface smoothness, and can suppress flow marks. It is particularly effective for components constituting motor vehicle lamps or lighting equipment, light reflector components with light reflective layers on their surfaces, etc.

[0033] <Polyester Resin A>

[0034] In this invention, polyester resin A contains 82-88% by mass of polybutylene terephthalate resin and 12-18% by mass of polyethylene terephthalate resin. Polyester resin A does not exclude the presence of a third component other than polybutylene terephthalate resin and polyethylene terephthalate resin, but it is preferably composed of these two components. There is no particular limitation on the amount of polyester resin A in the polyester resin composition, as long as it is the main component; preferably, it is 90% by mass or more, more preferably 92% by mass or more.

[0035] (Polybutylene terephthalate resin)

[0036] Polybutylene terephthalate resin is a polymer obtained by conventional polymerization methods, such as polycondensation of a dicarboxylic acid, mainly composed of terephthalic acid or its ester-forming derivative, with a diol, mainly composed of 1,4-butanediol or its ester-forming derivative. The repeating unit of butylene terephthalate in the polybutylene terephthalate resin is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and most preferably 100 mol%.

[0037] Without impairing its properties, polybutylene terephthalate resin may contain, for example, up to about 20% by weight of other polymeric components. Examples of polybutylene terephthalate resins containing other polymeric components include poly(terephthalic acid / isophthalic acid)butylene glycol, poly(terephthalic acid / adipic acid)butylene glycol, poly(terephthalic acid / sebacic acid)butylene glycol, poly(terephthalic acid / sebacic acid)butylene glycol, poly(terephthalic acid / naphthalenedicarboxylic acid)butylene glycol, and poly(butylene glycol / ethylene glycol) terephthalate. These components may be used alone or in combination of two or more.

[0038] The intrinsic viscosity (IV) of the polybutylene terephthalate resin is preferably 0.3–1.6 dl / g, more preferably 0.45–1.35 dl / g, even more preferably 0.5–1.2 dl / g, and particularly preferably 0.55–1.05 dl / g. The polyester resin composition of the present invention exhibits good mechanical properties and moldability by achieving an intrinsic viscosity (IV) of 0.3–1.6 dl / g for the polybutylene terephthalate resin. The aforementioned intrinsic viscosity (IV) is determined using an Ubbelohde viscometer, by measuring the fall time of a 0.4 g / dl polybutylene terephthalate resin solution and the solution in the mixed solvent (1 / 1 by mass) at 30°C, according to ASTM D4603 and calculated using the following formula (I).

[0039] Intrinsic viscosity (IV) = 0.25 (η) r -1+3lnη r ) / C···(I)

[0040] In the above formula (I), η r =η / η0, where η is the number of seconds the polybutylene terephthalate resin solution falls, η0 is the number of seconds the mixed solvent falls, and C is the concentration of the polybutylene terephthalate resin solution (g / dl).

[0041] The terminal carboxyl groups of polybutylene terephthalate (PET) resin act as catalysts in the polymer's hydrolysis reaction; therefore, hydrolysis is accelerated with increasing amounts of terminal carboxyl groups. Thus, a low concentration of these terminal carboxyl groups is preferred. The concentration of terminal carboxyl groups in PET resin is preferably 40 eq / ton or less, more preferably 30 eq / ton or less, further preferably 25 eq / ton or less, and particularly preferably 20 eq / ton or less.

[0042] The concentration of terminal carboxyl groups (in eq / ton) of polybutylene terephthalate resin can be determined by, for example, dissolving a specified amount of polybutylene terephthalate resin in benzyl alcohol and titrating it with a 0.01 mol / L sodium hydroxide solution of benzyl alcohol. Phenolphthalein solution can be used as an indicator, for example.

[0043] The terminal hydroxyl groups of polybutylene terephthalate (PET) resin primarily cause "backbiting" during melting, thus becoming an initiation point for the formation of THF, linear oligomers, and cyclic oligomers, which are forms of degassing during molding. Therefore, to reduce mold contamination, it is preferable to reduce the concentration of these terminal hydroxyl groups and suppress "backbiting" during molding. The concentration of the terminal hydroxyl groups in PET resin is preferably 110 eq / ton or less, more preferably 90 eq / ton or less, further preferably 70 eq / ton or less, and particularly preferably 50 eq / ton or less.

[0044] The concentration of terminal hydroxyl groups (unit: eq / ton) of polybutylene terephthalate resin can be determined according to, for example... 1 The spectrum obtained by H-NMR measurement is derived from the peak of terephthalic acid from polybutylene terephthalate and the peak of 1,4-butanediol at the end through predetermined calculations.

[0045] (Polyethylene terephthalate resin)

[0046] Polyethylene terephthalate resin is a polymer that can be obtained by conventional polymerization methods, such as the polycondensation reaction of dicarboxylic acid, mainly composed of terephthalic acid or its ester-forming derivatives, with diol, mainly composed of ethylene glycol or its ester-forming derivatives. The repeating unit of polyethylene terephthalate in the polyethylene terephthalate resin is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and particularly preferably 100 mol%.

[0047] Without impairing its properties, polyethylene terephthalate resin may contain, for example, less than 20% by mass of other polymeric components. Examples of polyethylene terephthalate resins containing other polymeric components include: polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sebacic acid), polyethylene (terephthalate / sebacic acid), polyethylene (terephthalate / sebacic acid), polyethylene (terephthalate / naphthalic acid), polyethylene (ethylene glycol / cyclohexanedimethyl) terephthalate, and polyethylene (butanediol / ethylene glycol) terephthalate. These components may be used alone or in mixtures of two or more. By using such polyethylene terephthalate resins, the molding shrinkage of the polyester resin composition can be controlled in this invention.

[0048] The intrinsic viscosity (IV) of the polyethylene terephthalate resin is preferably 0.36–1.6 dl / g, more preferably 0.45–1.35 dl / g, even more preferably 0.5–1.2 dl / g, and particularly preferably 0.55–1.05 dl / g. The polyester resin composition of the present invention exhibits good mechanical properties and moldability by achieving an intrinsic viscosity (IV) of 0.36–1.6 dl / g for the polyethylene terephthalate resin. The aforementioned intrinsic viscosity (IV) can be measured using the same method as that used for measuring the intrinsic viscosity (IV) of polybutylene terephthalate resin.

[0049] In this invention, to prevent the inorganic filler C from floating out and causing flow marks during molding, and to achieve a good surface appearance of the molded article, the polyester resin A contains 82-88% by mass of polybutylene terephthalate resin and 12-18% by mass of polyethylene terephthalate resin, with the aim of controlling the crystallization behavior of the polyester resin composition. As described above, by containing polyethylene terephthalate resin, the molding shrinkage rate of the polyester resin composition can be controlled. On the other hand, if the content of polyethylene terephthalate resin exceeds 18% by mass, the effect of suppressing flow marks cannot be sufficiently obtained; if it is less than 12% by mass, the molding shrinkage rate increases, the filler floats out, and the appearance deteriorates. Polyester resin A preferably contains 85-88% by mass of polybutylene terephthalate resin and 12-15% by mass of polyethylene terephthalate resin.

[0050] The total amount of polybutylene terephthalate resin and polyethylene terephthalate resin in polyester resin A is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Furthermore, the total amount of polybutylene terephthalate resin and polyethylene terephthalate resin may also be 100% by mass.

[0051] (Titanium catalyst)

[0052] The polybutylene terephthalate resin constituting the present invention can be obtained, for example, by esterification or transesterification of 1,4-butanediol with terephthalic acid or dialkyl terephthalate using a titanium catalyst. The content of the titanium catalyst in the polyester resin composition of the present invention is defined by the content of titanium atoms.

[0053] The titanium atomic content can be determined using methods such as atomic emission, atomic absorption, or ICP (inductively coupled plasma) after the metal in the polymer has been recovered by methods such as wet ashing.

[0054] As titanium catalysts, known titanium compounds can be used. Specific examples include: tetraalkyl titanates containing titanium alkoxides, such as tetraethyl titanate, tetraisopropyl titanate, tetran-propyl titanate, and tetran-butyl titanate; their partial hydrolysates and titanium chelates; titanium oxalate compounds such as titanium acetate, titanium oxalate, ammonium titanium oxalate, sodium titanium oxalate, potassium titanium oxalate, calcium titanium oxalate, and strontium titanium oxalate; titanium trimellitate; titanium sulfate; titanium chloride; hydrolysates of titanium halides; titanium bromide; titanium fluoride; potassium hexafluoride titanate; ammonium hexafluoride titanate; cobalt hexafluoride titanate; manganese hexafluoride titanate; titanium acetylacetonate; titanium complexes with hydroxy polycarboxylic acids or nitrogen-containing polycarboxylic acids; complex oxides containing titanium and silicon or zirconium; reactants of titanium alkoxides and phosphorus compounds; and reaction products of titanium alkoxides with aromatic polycarboxylic acids or their anhydrides with specified phosphorus compounds.

[0055] From the viewpoint of suppressing mold stains, tetraalkyl titanates containing titanium alkoxides, such as tetraethyl titanate, tetraisopropyl titanate, tetran-propyl titanate, and tetran-butyl titanate, are preferred; any one of the following groups consists of their partial hydrolysates and titanium chelates. Furthermore, any one of the following groups is more preferably used: tetraisopropyl titanate, tetran-propyl titanate, tetran-butyl titanate, ethyl acetoacetate titanium chelate, and titanium triethanolamine.

[0056] Tin can be used instead of titanium, or titanium can be used together with tin as a catalyst. Furthermore, in addition to titanium and tin, magnesium compounds such as magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxides, and magnesium hydrogen phosphate; calcium compounds such as calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxides, and calcium hydrogen phosphate; antimony compounds such as antimony trioxide; germanium compounds such as germanium dioxide and germanium tetroxide; manganese compounds; zinc compounds; zirconium compounds; cobalt compounds; phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, their esters or metal salts; and reaction promoters such as sodium hydroxide. When the compound used as a reaction promoter is repeated with the following organometallic acid salt B, the total amount of organometallic acid salt B and the reaction promoter should be within the range allowed for organometallic acid salt B in this invention.

[0057] (linear oligomers)

[0058] The invention is believed to be able to suppress mold contamination during continuous molding for the following reasons.

[0059] The polyester resin composition of this invention contains a polybutylene terephthalate (PBPT) linear oligomer content, or a content of PBPT and polyethylene terephthalate (PET) linear oligomers of PBPT and PET of PET of 1000 mg / kg or less. In this invention, PBPT resin constitutes the largest proportion of the polyester resin composition; therefore, it is preferable to reduce the content of PBPT linear oligomers. Linear oligomers have lower melting points and lower glass transition temperatures than cyclic oligomers, and therefore adhere more readily to the mold compared to cyclic oligomers. It is believed that linear oligomers adhering to the mold possess adhesive properties, acting as a binder to facilitate the adhesion of cyclic oligomers to the mold. Therefore, reducing the content of linear oligomers in the polyester resin composition effectively helps to delay the onset of mold contamination during continuous molding. Therefore, reducing the content of linear oligomers is crucial for suppressing mold contamination.

[0060] Thus, in this invention, linear oligomers were found to be the root cause of mold contamination. Furthermore, tetrahydrofuran is known to be generated through a "backbiting" reaction of terminal hydroxyl groups, and the degassing test described below revealed a positive correlation between the amount of tetrahydrofuran generated and the degree of mold contamination. That is, the greater the amount of tetrahydrofuran generated, the more severe the mold contamination. In this degassing test, a sample of 5 mg of polyester resin composition was heated at 265°C for 10 minutes, and the resulting components were analyzed by GC / MS (trade name: "TD-20 / QP-2010Ultra", manufactured by Shimadzu Corporation) to determine the amount of tetrahydrofuran generated. The detected components can be quantified by conversion to toluene, etc. Additionally, mold contamination can be evaluated by performing accelerated tests as described below.

[0061] As can be seen from the above, the linear oligomers contained in the polyester resin composition are ejected from the resin system during injection molding in the form of tetrahydrofuran generated during molding, and come into contact with the mold. It is assumed that the low-boiling-point tetrahydrofuran evaporates without remaining in the mold, but the linear oligomers dissolved in the tetrahydrofuran adhere directly to the mold. Therefore, reducing the amount of tetrahydrofuran generated as a medium is also related to suppressing the distillation of linear oligomers from the resin system, resulting in a reduction in the amount of linear oligomers adhering to the mold and suppressing mold contamination.

[0062] In this specification, when the linear oligomer is a polybutylene terephthalate linear oligomer, it refers to an oligomer with a linear structure comprising a total of 2 to 13 structural units derived from terephthalic acid and structural units derived from 1,4-butanediol. Similarly, when the linear oligomer is a polyethylene terephthalate linear oligomer, it refers to an oligomer with a linear structure comprising a total of 2 to 13 structural units derived from terephthalic acid and structural units derived from ethylene glycol. There are also cases where the linear oligomer has reactive functional groups containing hydroxyl or carboxyl groups at both ends, with both ends being carboxyl or hydroxyl groups. Furthermore, when the cyclic oligomer is a polybutylene terephthalate cyclic oligomer, it refers to an oligomer with a cyclic structure comprising a total of 4 to 14 structural units derived from terephthalic acid and structural units derived from 1,4-butanediol. Furthermore, when the cyclic oligomer is a polyethylene terephthalate cyclic oligomer, it refers to an oligomer with a total of 4 to 14 cyclic structural units derived from terephthalic acid and structural units derived from ethylene glycol.

[0063] As described above, the content of polybutylene terephthalate linear oligomers, or the content of both polybutylene terephthalate linear oligomers and polyethylene terephthalate linear oligomers, in the polyester resin composition of the present invention is 1000 mg / kg or less. The content of linear oligomers is preferably 950 mg / kg or less, more preferably 900 mg / kg or less, even more preferably 800 mg / kg or less, and particularly preferably 700 mg / kg or less. When the content of linear oligomers is greater than 1000 mg / kg, the effect of suppressing mold contamination is insufficient. Ideally, the lower limit of the linear oligomer content is 0 mg / kg. It should be noted that, regarding the content of linear oligomers, when both polybutylene terephthalate linear oligomers and polyethylene terephthalate linear oligomers are present, both are 1000 mg / kg or less.

[0064] On the other hand, the content of cyclic oligomers should be below 9000 mg / kg. Preferably, the content of cyclic oligomers is below 8000 mg / kg, more preferably 6000 mg / kg. However, even if the content of cyclic oligomers is around 6000 mg / kg, the effect of inhibiting mold contamination will decrease when the content of linear oligomers exceeds 1000 mg / kg. If the content of linear oligomers is below 1000 mg / kg, the lower the content of cyclic oligomers, the better the effect of inhibiting mold contamination. In this regard, if the content of linear oligomers is below 1000 mg / kg, the content of cyclic oligomers considered to be the cause of previous mold contamination can be relatively flexibly allowed to be up to 9000 mg / kg or less.

[0065] The content of linear and cyclic oligomers can be determined by, for example, dissolving the polyester resin composition in a solvent consisting of hexafluoroisopropanol / chloroform = 2 / 3 (volume ratio), adding chloroform, methanol, etc., to precipitate it. Then, the filtered supernatant is dried, dissolved in dimethylformamide, filtered, and analyzed by liquid chromatography. For example, the content (quantitative value) of linear oligomers can be calculated by converting it to BHET (dihydroxyethyl terephthalate), and the content (quantitative value) of cyclic oligomers can be calculated by converting it to polyethylene terephthalate cyclic trimers.

[0066] The method for reducing the content of linear oligomers to below 1000 mg / kg is not particularly limited, as long as it enables the content of linear oligomers to be below 1000 mg / kg. In this invention, since the proportion of polybutylene terephthalate resin in the polyester resin composition is relatively high, reducing the content of polybutylene terephthalate linear oligomers is effective.

[0067] Methods for reducing the content of linear oligomers to below 1000 mg / kg include: methods using titanium catalysts and reaction aids, solid-state polymerization, and extraction of linear oligomers using water or solvents. Methods for reducing the content of cyclic oligomers to below 9000 mg / kg are not particularly limited; examples include: methods for adjusting the temperature, time, and polymerization catalyst during the polymerization of polybutylene terephthalate resin; solid-state polymerization; heat treatment in the molten state after polymerization; and extraction of cyclic oligomers using a specified solvent. Furthermore, these methods can be combined with other methods to reduce both linear and cyclic oligomers.

[0068] For example, in the solid-state polymerization of polybutylene terephthalate resin, esterification or transesterification is carried out, thereby tending to decrease the concentrations of both terminal carboxyl groups and terminal hydroxyl groups. In this method, due to the increase in molecular weight, it is necessary to adjust the intrinsic viscosity (IV) before solid-state polymerization, as well as the temperature and time of solid-state polymerization.

[0069] Furthermore, when the polyester resin composition contains polyethylene terephthalate resin, reducing the content of polyethylene terephthalate linear oligomers also helps to suppress mold contamination. In addition, methods for reducing the generation of tetrahydrofuran are detailed below.

[0070] <Organometallic acid salt B>

[0071] The polyester resin composition of this invention contains organometallic acid salt B, which is one or both of alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts. Its content is determined based on the content of one or both of alkali metal atoms and alkaline earth metal atoms. Specifically, relative to 100 parts by mass of the aforementioned polyester resin A, it contains 0.000005 to 0.05 parts by mass of one or both of alkali metal atoms and alkaline earth metal atoms. That is, in this invention, the content of organometallic acid salt B in the polyester resin composition is determined by determining the content of one or both of alkali metal atoms and alkaline earth metal atoms. When the polyester resin composition contains both alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts, the content is the total amount of both alkali metal atoms and alkaline earth metal atoms.

[0072] The reason for determining the content of organometallic acid salt B in the polyester resin composition by measuring the content of either or both of the alkali metal atoms and alkaline earth metal atoms is as follows. In the polyester resin composition, organometallic acid salt B is assumed to exist in a state of metal ion dissociation. Therefore, to know the content of organometallic acid salt B, it is necessary to quantify either or both of the metal (ions) and organic acid (ions). However, organic acids are volatile, and many have structures similar to polymers such as polybutylene terephthalate, making quantification difficult in many cases. On the other hand, metal atoms (alkali metal atoms and alkaline earth metal atoms) are relatively easy to retain in the polyester resin composition and are relatively easy to quantify. Therefore, the content of organometallic acid salt B in the polyester resin composition is determined by measuring the content of either or both of the alkali metal atoms and alkaline earth metal atoms. Furthermore, for these reasons, it can be clearly determined that either or both of the aforementioned alkali metal atoms and alkaline earth metal atoms originate from organometallic acid salt B.

[0073] Therefore, the content of alkali metal atoms and alkaline earth metal atoms in the polyester resin composition can be determined by ICP luminescence analysis.

[0074] In other words, the polyester resin composition of the present invention contains, per 1 kg of polyester resin A, either or both of alkali metal atoms and alkaline earth metal atoms, at a concentration of 0.05 mg or more and 500 mg or less (hereinafter expressed as "mg / kg"). Furthermore, when the organometallic acid salt B comprises both alkali metal organic acid salts and alkaline earth metal organic acid salts, relative to 100 parts by mass of the above-mentioned polyester resin A, the total content of alkali metal atoms and alkaline earth metal atoms is 0.000005 to 0.05 parts by mass.

[0075] Organometallic acid salt B can reduce the "biting" reaction of terminal hydroxyl groups in polybutylene terephthalate (PET) and polyethylene terephthalate (PET) resins during molding, thereby reducing the amount of THF generated. However, when the amount of either or both of the alkali metal atoms and alkaline earth metal atoms from organometallic acid salt B is less than 0.000005 parts by mass (0.05 mg / kg) relative to 100 parts by mass of polyester resin A, the effect of organometallic acid salt B in inhibiting mold contamination is not significant. Furthermore, when the amount of either or both of the alkali metal atoms and alkaline earth metal atoms is greater than 0.05 parts by mass (500 mg / kg) relative to 100 parts by mass of polyester resin A, it promotes the decomposition of the polyester resin composition, potentially leading to mold contamination and decreased fogging resistance.

[0076] Further, relative to 100 parts by weight of the above-mentioned polyester resin A, the polyester resin composition preferably contains 0.0005 to 0.05 parts by weight of any one or both of alkali metal atoms and alkaline earth metal atoms. This numerical range is more preferably 0.0005 to 0.04 parts by weight (5 to 400 mg / kg), even more preferably 0.0006 to 0.03 parts by weight (6 to 300 mg / kg), and particularly preferably 0.0007 to 0.02 parts by weight (7 to 200 mg / kg).

[0077] From the viewpoint of mold staining, the metal type of the organometallic acid salt B that can be used in the polyester resin composition of the present invention is preferably selected from one or more of the group consisting of lithium, sodium, potassium, calcium, and magnesium. Among them, lithium, sodium, and potassium are preferred, and potassium is most preferred.

[0078] Specifically, examples of alkali metal or alkaline earth metal salts include: saturated aliphatic carboxylates such as formic acid, acetic acid, propionic acid, butyric acid, and oxalic acid; unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid; aromatic carboxylates such as benzoic acid; halogenated carboxylates such as trichloroacetic acid; hydroxycarboxylates such as lactic acid, citric acid, salicylic acid, and gluconic acid; organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid, and naphthalenesulfonic acid; organic sulfates such as lauryl sulfate; and carbonates. Furthermore, while carbonates are generally considered inorganic acid salts, in this invention, acids containing carbon are considered organic acids, and carbonates are included within the scope of organic acid salts.

[0079] From the viewpoint of suppressing mold contamination and operability, organometallic acid salt B is preferably selected from one or more of the group consisting of lithium acetate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, lithium benzoate, sodium benzoate, and potassium benzoate. More preferably, it is selected from one or more of the group consisting of lithium acetate, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate, and particularly preferably, potassium acetate. Furthermore, these organometallic acid salts B can be used alone or in combination of two or more.

[0080] There are no particular limitations on the method of including organometallic acid salt B in the polyester resin composition. For example, methods may include: adding it during the initial stage of polymerization of the polybutylene terephthalate resin constituting polyester resin A (after esterification or transesterification); adding it during the later stage of polymerization of the polybutylene terephthalate resin (during the polycondensation process (reduced pressure process) or after polymerization); attaching it to the surface of the granules or penetrating it into the granules after granulation; or pre-preparing a masterbatch containing a high concentration of organometallic acid salt B and mixing the masterbatch during melt mixing to obtain the polyester resin composition. Furthermore, it is also possible to add the masterbatch containing a high concentration of organometallic acid salt B during molding the molded body. Additionally, the aforementioned initial and later stages of polymerization of the polybutylene terephthalate resin refer to the initial and later stages of polymerization of the polybutylene terephthalate resin during so-called melt polymerization.

[0081] When manufacturing polybutylene terephthalate resin containing organometallic acid salt B, a portion of the added organometallic acid salt B is removed from the reaction system under reduced pressure. Therefore, the amount of organometallic acid salt B added needs to be determined after several experiments, taking into account the reaction apparatus and conditions used, to ascertain the amount of organometallic acid salt B (i.e., any one or both of alkali metal atoms and alkaline earth metal atoms) remaining in the polyester resin composition. Furthermore, when the polyester resin composition of the present invention is compounded and manufactured using a twin-screw extruder or similar equipment, the same situation occurs during degassing (reduced pressure), thus requiring necessary measures to determine the amount of organometallic acid salt B added.

[0082] In particular, in this invention, when a polyester resin composition is formed by containing 0.0005 to 0.05 parts by mass (5 to 500 mg / kg) of either or both of the alkali metal atoms and alkaline earth metal atoms from organometallic acid salt B relative to 100 parts by mass of polyester resin A, it is preferable to obtain the polyester resin composition by using a masterbatch containing a high concentration of organometallic acid salt B. The matrix resin of the masterbatch is preferably any type of resin constituting the polyester resin composition, more preferably polybutylene terephthalate resin, which constitutes the largest proportion of the polyester resin composition. The masterbatch containing a high concentration of organometallic acid salt B can be manufactured by mixing the matrix resin and organometallic acid salt B and then melt-blending. This melt-blending method can be a known method, and a single-screw extruder, a twin-screw extruder, a pressure kneader, or a Banbury mixer can be used. A twin-screw extruder is preferred.

[0083] The content of organometallic acid salt B in the masterbatch is also determined based on the content of any one or both of alkali metal atoms and alkaline earth metal atoms. Relative to 100 parts by weight of the masterbatch, the content of any one or both of alkali metal atoms and alkaline earth metal atoms is preferably 0.02 to 1.5 parts by weight (200 to 15000 mg / kg). When the content in the masterbatch is greater than 1.5 parts by weight, the matrix resin may decompose during masterbatch manufacturing, potentially causing adverse effects when present in the polyester resin composition. When the content in the masterbatch is less than 0.02 parts by weight, the content of organometallic acid salt B is low, resulting in poor productivity.

[0084] The reason why these organometallic acid salts B have the effect of inhibiting mold contamination is speculated to be as follows: Organometallic acid salts B inhibit the hydrolysis reaction of polybutylene terephthalate resin through the effect of stabilizing ester groups, or a so-called "buffering" effect, and inhibit the "backbiting" reaction of terminal hydroxyl groups. Thus, the generation of tetrahydrofuran can be mainly inhibited. Therefore, the polyester resin composition of the present invention can achieve a significant inhibitory effect on low gas content and mold contamination.

[0085] In a method of making a polyester resin composition contain organometallic acid salt B, it is more preferable to add a pre-made masterbatch of organometallic acid salt B during the mixing or molding of the polyester resin composition than to add organometallic acid salt B during the polyester polymerization process, for the following reasons.

[0086] When organometallic acid salt B is added at the initial stage of polymerization (after esterification or transesterification) and the later stage of polymerization (during condensation (reduced pressure process) or after polymerization) of polybutylene terephthalate (PET) resin constituting polyester resin A, the alkali metal or alkaline earth metal in the terephthalic acid and organometallic acid salt B, which are its raw materials, form salts, thus losing the function of organometallic acid salt B and potentially reducing its effectiveness in inhibiting mold staining. Furthermore, the formed salts precipitate as seeds, resulting in an unsatisfactory appearance (especially a smooth, mirror-like finish). These precipitated salts and other foreign matter become the starting point for material degradation, and mechanical properties may also decrease (when organometallic acid salt B is added after polymerization, the resin viscosity is high, making uniform dispersion difficult, and in some cases, organometallic acid salt B itself may become a seed).

[0087] On the other hand, when a pre-made masterbatch of organometallic acid salt B is added during the mixing or molding of the polyester resin composition, the time when polyester resin A is in the molten state can be shortened in the presence of organometallic acid salt B. Not only are the above-mentioned problems solved, but the decomposition of polyester resin A is also reduced. Therefore, the deterioration of the color (increased yellowness) can be suppressed, and the fogging resistance can also be maintained.

[0088] Therefore, adding organometallic acid salt B as a masterbatch during the compounding or molding of polyester resin compositions is more preferable than adding it during the polymerization of polybutylene terephthalate resin.

[0089] The polyester resin composition of the present invention contains an organometallic acid salt B, thereby increasing the Color-b value of the L*a*b* color system and tending to increase yellowness. From the viewpoint of quality and color difference during coloring, the Color-b value of the polyester resin composition is preferably controlled to be 6 or less. Here, compared with the method of adding organometallic acid salt B during the polymerization of polybutylene terephthalate resin, the method of adding organometallic acid salt B through masterbatch tends to have a lower Color-b value, and is therefore preferred. The Color-b value of the polyester resin composition is more preferably 5 or less, and even more preferably 4 or less.

[0090] Color-b values ​​are obtained by, for example, by measuring the mirror surface of a flat plate with a mirrored surface on one side (molded using a mold with a mirrored surface) obtained by injection molding a polyester resin composition, using a commercially available precision spectrophotometer or similar instrument according to JIS Z 8722:2009 and JIS Z 8781-4:2013.

[0091] <Inorganic packing C>

[0092] The polyester resin composition of this invention contains 1 to 13 parts by weight of inorganic filler C with an average particle size of 0.05 to 3 μm, relative to 100 parts by weight of polyester resin A. By keeping the inorganic filler C within this range, heat resistance and rigidity can be further improved, and shrinkage can be further controlled to a lower level. Especially when the shrinkage rate is high, poor demolding can occur during injection molding due to mold adhesion, and the molded product may deform if it is large or has a complex shape. Therefore, it is very important to control the shrinkage rate to a low level using inorganic filler C.

[0093] When the content of inorganic filler C is less than 1 part by mass, the improvement in heat resistance and rigidity is minimal. If it exceeds 1 / 3 part by mass, the float-out of the filler will damage the surface smoothness necessary for use as a lamp component.

[0094] From the viewpoints of improving heat resistance and rigidity, and surface smoothness, the content of inorganic filler C is preferably 2 parts by mass or more. Further from the viewpoint of shrinkage control, the content of inorganic filler C is more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more. From the viewpoint of surface smoothness, the content of inorganic filler C is preferably 11 parts by mass or less, and more preferably 9 parts by mass or less.

[0095] The average particle size (50% diameter of the volumetric cumulative particle size distribution) of the inorganic filler C, as determined by laser diffraction, must be below 3 μm. When the average particle size exceeds 3 μm, the surface smoothness of the molded polyester resin composition is compromised. The average particle size of the inorganic filler C is preferably below 2 μm. From the viewpoints of suppressing aggregation (poor dispersion) and handling (ease of feeding, etc.), the lower limit of the average particle size of the inorganic filler C is preferably 0.05 μm.

[0096] The inorganic filler C is preferably one or more selected from the group consisting of calcium carbonate, silica, kaolin, and barium sulfate. Since these inorganic fillers can produce smaller particle sizes compared to others, surface smoothness is easily maintained even with large addition amounts. From the viewpoint of reducing the specific gravity of the polyester resin composition, calcium carbonate, silica, and kaolin are preferred; from the viewpoint of dispersibility and workability in the polyester resin composition, calcium carbonate is more preferred.

[0097] To improve compatibility with and dispersibility within the polyester resin composition, the inorganic filler C may be surface-treated. Furthermore, when surface treatment is performed, it is preferable to perform the treatment to the extent that it does not affect other properties such as fogging caused by gas generation.

[0098] Examples of surface treatments include: treatment with surface treatment agents such as aminosilane coupling agents, epoxysilane coupling agents, and aluminate coupling agents; silica treatment; fatty acid treatment; SiO2-Al2O3 treatment; neutralization treatment with acidic compounds such as phosphorus compounds, etc., and combinations of these treatments are also possible. From the viewpoint of fog resistance, silica treatment, epoxysilane coupling agent treatment, and alkylsilane coupling agent treatment are preferred.

[0099] There are no particular limitations on the surface treatment method of inorganic filler C. For example, the inorganic filler C can be physically mixed with various treatment agents. Pulverizers such as roller mills, high-speed rotary pulverizers, and air jet mills can be used; or mixers such as spiral mixers (Nautamixer), ribbon mixers, and Henschel mixers can be used.

[0100] <Other>

[0101] (Mold Release Agent D)

[0102] To further improve mold release properties, the polyester resin composition of the present invention may contain a mold release agent D. From the viewpoint of suppressing mold stains, the mold release agent D is preferably a fatty acid ester compound. This fatty acid ester compound may contain a compound in which a portion of a carboxylic acid is esterified by a monoglycol or polyglycol, and a compound in which a metal salt is formed. The content of the mold release agent D is preferably 0.05 to 3 parts by mass relative to 100 parts by mass of polyester resin A. When the content of the mold release agent D is less than 0.05 parts by mass, sufficient mold release effect cannot be obtained, and poor mold release or mold wrinkling may occur. The mold release agent D causes mold stains through its own vaporization or exudation. Furthermore, for example, when the polyester resin composition containing the mold release agent D is applied to automotive lamps, it adheres to headlight covers or mirrors at temperatures ranging from 100°C to 200°C, causing fogging (fogging). These problems become significant when the content of the mold release agent D is greater than 3 parts by mass.

[0103] The polyester resin composition of the present invention, having the specific configuration described above, can achieve a maximum height roughness (Rz) of 100mm × 100mm × 2mm (length 100mm, width 100mm, thickness 2mm) of flat plate by injection molding with a mirror-finished mold polished with a #16000 abrasive, at a molding temperature of 260°C, a mold temperature of 45°C, and a filling time of 4.5 seconds or more. Preferably, the maximum height roughness (Rz) of the flat plate is 0.50μm or less.

[0104] <Method for manufacturing polyester resin composition>

[0105] The polyester resin composition of the present invention can be manufactured by melt-blending the above-mentioned components and additives such as stabilizers added as needed. The melt-blending method can use known methods, such as a single-screw extruder, a twin-screw extruder, a pressure kneader, or a Banbury mixer. A twin-screw extruder is preferred. As general melt-blending conditions, when using a twin-screw extruder, the barrel temperature can be set to 250–280°C, and the blending time to 2–15 minutes.

[0106] There is no particular limitation on the molding method of the polyester resin composition of the present invention, and known methods such as injection molding, extrusion molding, and blow molding can be used. Among these methods, injection molding is preferred from the viewpoint of versatility.

[0107] <Components for light reflectors>

[0108] The light reflector component of the present invention comprises the above-described polyester resin composition. The light reflector component can be obtained by molding the polyester resin composition using known methods such as injection molding, extrusion molding, and blow molding; from a general viewpoint, injection molding is preferred. The light reflector component, for example, includes a light-reflective metal layer, thereby becoming the light reflector described below.

[0109] <Light reflector>

[0110] The light reflector of the present invention has a light-reflecting metal layer formed on at least a portion of the surface of the aforementioned light reflector component. For example, the light reflector can be obtained by directly forming a metal thin film (e.g., aluminum foil) as the light-reflecting metal layer on at least a portion of the surface of the aforementioned light reflector component. In particular, the light reflector is preferably obtained by vapor-depositing a metal thin film on at least a portion of the surface of the aforementioned light reflector component. The vapor deposition method is not particularly limited, and known methods can be used.

[0111] The light reflector of the present invention can be used as, for example, motor vehicle lamps (headlights, etc.), light reflectors (extensions, reflector bowls, housings, etc.), as well as various components such as lighting equipment, electrical components, electronic components, and household items.

[0112] Example

[0113] The present invention will be further described in detail below by way of examples, but the present invention is not limited to these examples. Furthermore, the measurement values ​​described in the examples are values ​​determined according to the following method.

[0114] (1) Intrinsic viscosity (IV): The intrinsic viscosity (IV) of polybutylene terephthalate resin a and polyethylene terephthalate resin b was determined at 30°C using an Ubbelohde viscometer and a mixed solvent of phenol / tetrachloroethane (mass ratio 1 / 1). The falling time of a 0.4 g / dl solution of polybutylene terephthalate resin a, a 0.4 g / dl solution of polyethylene terephthalate resin b, and the mixed solvent alone at 30°C was measured, and the value was calculated using the above formula (I).

[0115] (2) Terminal carboxyl group concentration (unit: eq / ton, expressed as acid value): 0.5 g of polybutylene terephthalate resin a was dissolved in 25 ml of benzyl alcohol and titrated with a benzyl alcohol solution containing 0.01 mol / L sodium hydroxide. The indicator used was a solution obtained by dissolving 0.10 g of phenolphthalein in a mixture of 50 ml of ethanol and 50 ml of water. The terminal carboxyl group concentration of polyethylene terephthalate resin b was also quantified using the same method.

[0116] (3) Terminal hydroxyl concentration (unit: eq / ton): The quantitative determination of the terminal hydroxyl concentration of polybutylene terephthalate resin a was performed using a resonance frequency of 500MHz. 1 Quantification was performed using 1H-NMR measurements. The measuring apparatus used was an NMR instrument (trade name: "AVANCE-500", manufactured by BRUKER).

[0117] First, either 10 mg of polybutylene terephthalate resin a or 10 mg of polyethylene terephthalate resin b was dissolved in 0.12 ml of a solvent composed of deuterated chloroform / hexafluoroisopropanol in a 1:1 (volume ratio). Then, 0.48 ml of deuterated chloroform and 5 μl of deuterated pyridine were added, and the mixture was stirred thoroughly to prepare a resin solution. Finally, this resin solution was filled into an NMR tube for NMR analysis. 1 ¹H-NMR determination. Deuterated chloroform was used as the field-locking solvent, and the number of scans was set to 128.

[0118] Next, in the measurement 1 When the chloroform peak appears at 7.29 ppm in the ¹H-NMR spectrum, the terephthalic acid peak (i) from polybutylene terephthalate or polyethylene terephthalate appears at 8.10 ppm. Further, for polybutylene terephthalate resin a, the terminal 1,4-butanediol peak (ii) appears at 3.79 ppm. For polyethylene terephthalate resin b, the terminal ethylene glycol peak (iii) appears at 4.03 ppm. Therefore, the concentration of terminal hydroxyl groups is calculated by integrating (i) to (iii) as the peak values, according to the following formula.

[0119] For polybutylene terephthalate resin a: {(ii)×1000000 / 2} / {(i)×220 / 4}=terminal hydroxyl concentration (eq / ton)

[0120] For polyethylene terephthalate resin b: {(iii)×1000000 / 2} / {(i)×192 / 4}=terminal hydroxyl concentration (eq / ton).

[0121] (4) Titanium, potassium and magnesium atomic contents: The polyester resin composition was wet decomposed with high-purity sulfuric acid and high-purity nitric acid for the electronics industry, and determined by luminescence analysis using ICP (trade name: "SPECTROBLUE", manufactured by Ametek).

[0122] (5) Oligomer content: 0.1 g of the polyester resin composition was dissolved in 3 ml of a solvent consisting of hexafluoroisopropanol / chloroform = 2 / 3 (volume ratio), followed by the addition of 20 ml of chloroform and 10 ml of methanol to precipitate the polymer. The filtered supernatant was then dried, dissolved in 10 ml of dimethylformamide, and filtered. The filtrate was analyzed by liquid chromatography to quantify each oligomer component. The quantitative values ​​of linear oligomers were converted to BHET (dihydroxyethyl terephthalate), and the quantitative values ​​of cyclic oligomers were converted to polyethylene terephthalate cyclic trimers, using calibration curves. The determination was performed under the following conditions.

[0123] Liquid Chromatography Analysis Apparatus: Trade name: "Prominence", manufactured by Shimadzu Corporation.

[0124] Chromatographic column: Shim-pack XR-ODS 2.2μm (3×100mm)

[0125] Mobile phase: A. 0.2% acetic acid in water, B. acetonitrile

[0126] Gradients: 0 min (10% B), 25 min (100% B), 27 min (100% B), 27.01 min (10% B), 32 min (10% B)

[0127] Flow rate: 1.1 ml / min

[0128] Column temperature: 50℃

[0129] Injection volume: 5 μl

[0130] Detection wavelength: UV258nm.

[0131] (6) Color-b value (flat surface): An injection molding machine (trade name: "EC100N", manufactured by Toshiba Machine Co., Ltd.) was used. A flat surface molded product of 100mm × 100mm × 2mm polyester resin composition was obtained by injection molding using a mold with a mirror surface polished with a #6000 file. The flat surface molded product has a mirror surface transferred from the mold on one side. The barrel temperature during molding was 260°C, and the mold temperature was 60°C. The Color-b value of the mirror side of the flat surface molded product was measured using a precision spectrophotometer (trade name: "TC-1500SX", manufactured by Tokyo Denshoku Co., Ltd.) according to JIS Z 8722:2009 and JIS Z 8781-4:2013. The measurement conditions were D65 light source, 10° field of view, and the 0°-d method was used.

[0132] (7) Accelerated Mold Contamination Test: An injection molding machine (trade name: "EC100N", manufactured by Toshiba Machine Co., Ltd.) was prepared, along with a continuous molding evaluation mold (a cavity with an outer diameter of 30 mm, an inner diameter of 20 mm, and a thickness of 3 mm, with a recessed section at the flow end that does not release gas). Using this mold, a polyester resin composition was continuously molded using a short-shot method to facilitate the accumulation of mold contamination components such as degassing and oligomers in the recessed section opposite the gate, thereby observing the degree of mold contamination. Molding was performed at a barrel temperature of 260°C, a mold temperature of 50°C, and a cycle time of 40 seconds. Mold contamination was evaluated after 20 injections. Mold contamination was photographed with a digital camera, and grayscale images were used for visual evaluation to ensure color uniformity.

[0133] A: No pollution was observed;

[0134] B: Almost no pollution was observed;

[0135] C: A faint contamination can be seen near the center of the recess on the opposite side of the gate;

[0136] D: The contamination outline near the center of the recess on the opposite side of the gate is clearly visible and black.

[0137] (8) Mirror appearance (visual inspection, maximum height roughness)

[0138] An injection molding machine (trade name: "EC100N", manufactured by Toshiba Machine Co., Ltd.) was prepared. A mold with a mirror finish polished with a #16000 file was used to injection mold a flat product consisting of a 100mm × 100mm × 2mm polyester resin composition. This flat product has a mirror finish transferred from the mold on one side. The barrel temperature during molding was 260°C, and the mold temperature was 45°C. Molding was performed with a filling time of 4.5 seconds or more to facilitate flow marks and filler floatation. Defects (whitening, surface roughness, flow marks) caused by flow marks and filler floatation on the mirror finish of the molded product were evaluated visually and by maximum height roughness (Rz). Maximum height roughness (Rz) was evaluated using a laser microscope (trade name: "Color 3D Laser Microscope VK-9700", manufactured by KEYENCE Co., Ltd.), magnified 20x, measuring five locations within a 10mm range from the flow end, and evaluating the maximum height roughness among them.

[0139] (Visual inspection of the mirror finish)

[0140] ◎: No whitening, rough surface, or flow marks.

[0141] 〇: Based on visual inspection, slight whitening, surface roughness, and flow marks were observed, but there are no problems in actual use.

[0142] ×: There is obvious whitening, rough surface, and flow marks.

[0143] (Maximum height roughness of mirror appearance (Rz))

[0144] 〇: Maximum height roughness (Rz) is below 0.70 μm.

[0145] ×: Maximum height roughness (Rz) exceeds 0.70 μm.

[0146] (9) Heat distortion temperature (load: 0.45MPa)

[0147] Using an injection molding machine (trade name: "EC100N", manufactured by Toshiba Machine Co., Ltd.), a multi-purpose test piece conforming to ISO-3167 was formed under conditions of a barrel temperature of 260°C and a mold temperature of 60°C. The heat distortion temperature of the multi-purpose test piece under a load of 0.45 MPa was determined according to ISO-75.

[0148] (10) Molding shrinkage

[0149] Using an injection molding machine (trade name: "EC100N", manufactured by Toshiba Machine Co., Ltd.), a flat molded product of 100mm × 100mm × 2mm polyester resin composition was obtained by injection molding under conditions of barrel temperature 260°C and mold temperature 60°C. After 24 hours of molding, the flow direction and the width of the molded product perpendicular to the flow direction were measured with vernier calipers. The molding shrinkage rate (average value of molding shrinkage rate in the flow direction and the perpendicular direction) was calculated according to the following formula.

[0150] Molding shrinkage rate: [{100 - (width of the molded part in the flow direction)} / 100 + {100 - (width of the molded part in the right-angle direction)} / 100] / 2

[0151] The mixed components used in the examples and comparative examples are shown below.

[0152] Polyester resin A comprises any one of the following polybutylene terephthalate resins a, or comprises any one of the following polybutylene terephthalate resins a and polyethylene terephthalate resin b.

[0153] Polybutylene terephthalate resin a uses any of the following.

[0154] a-1: IV = 0.83 dl / g, terminal hydroxyl group = 95 eq / ton, acid value = 9 eq / ton, titanium atom content = 80 mg / kg (using melt-polymerized resin with IV = 0.78 dl / g, solid-state polymerization was carried out at 210°C until IV = 0.83 dl / g was achieved). Potassium acetate 10 mg / kg was added as organometallic acid salt B during the melt polymerization of the above melt-polymerized resin (after esterification reaction).

[0155] a-2: IV = 0.83 dl / g, terminal hydroxyl group = 95 eq / ton, acid value = 9 eq / ton, titanium atom content = 80 mg / kg (using melt-polymerized resin with IV = 0.78 dl / g, solid-state polymerization was carried out at 210℃ until IV = 0.83 dl / g was achieved). During melt mixing, organometallic acid salt B was added through the masterbatch.

[0156] a-3: IV = 0.83 dl / g (resin obtained by melt polymerization), terminal hydroxyl group = 100 eq / ton, acid value = 10 eq / ton, titanium atom content = 80 mg / kg (no special treatment to reduce linear oligomer content was performed). Potassium acetate 10 mg / kg was added as organometallic acid salt B during the melt polymerization of the above resin (after esterification).

[0157] a-4: IV = 0.83 dl / g, terminal hydroxyl group = 95 eq / ton, acid value = 9 eq / ton, titanium atom content = 30 mg / kg (using melt-polymerized resin with IV = 0.78 dl / g, solid-phase polymerization was carried out at 210℃ until IV = 0.83 dl / g was achieved). No organometallic acid salt B was added.

[0158] a-5: IV = 0.83 dl / g (resin obtained through melt polymerization), terminal hydroxyl group = 100 eq / ton, acid value = 10 eq / ton, titanium atom content = 80 mg / kg (without special treatment to reduce linear oligomer content). Organometallic acid salt B was added through masterbatch during melt mixing.

[0159] In addition, for polybutylene terephthalate resins a-1 and a-3, organometallic acid salt B composed of potassium acetate in the above-mentioned amount is added during melt polymerization (after esterification). The residual amount (content) of organometallic acid salt B in the polyester resin composition is shown in Tables 1 and 2 below. For polybutylene terephthalate resins a-2 and a-5, organometallic acid salt B composed of potassium acetate is added to the pre-prepared masterbatch during melt mixing to adjust to the content shown in Tables 1 and 2 below. For polybutylene terephthalate resin a-4, no organometallic acid salt B is added.

[0160] Polyethylene terephthalate resin b: IV = 0.62 dl / g, acid value = 30 eq / ton.

[0161] The following compound was used as organometallic acid salt B.

[0162] B-1: Potassium acetate (manufactured by Wako Pure Chemical Industries, Ltd.)

[0163] B-2: Masterbatch of potassium acetate (manufactured by Wako Pure Chemical Industries, Ltd.).

[0164] Furthermore, the matrix resin used as the masterbatch is the same polybutylene terephthalate resin present in the polyester resin composition to be added. The content of organometallic acid salt B in the masterbatch is 0.2 parts by mass of potassium atoms per 100 parts by mass of the masterbatch.

[0165] The following compound was used as inorganic filler C.

[0166] The average particle size below represents the value determined by laser diffraction (50% of the volumetric cumulative particle size distribution).

[0167] C-1: Light calcium carbonate [Trade name: "RK-92BR3F", manufactured by Shiraishi Kogyo Co., Ltd. (treated with silica / epoxysilane coupling agent, average particle size 0.15μm)]

[0168] C-2: Light calcium carbonate [Trade name: "RK-82BR1F", manufactured by Shiraishi Kogyo Co., Ltd. (treated with silica / alkylsilane coupling agent, average particle size 0.15μm)]

[0169] C-3: Light calcium carbonate [Trade name: "RK-87BR2F", manufactured by Shiraishi Kogyo Co., Ltd. (silica-treated, average particle size 0.15μm)]

[0170] C-4: Fused silica [Trade name: "MC3000", manufactured by Kinseimatec Co., Ltd. (average particle size 1.2 μm)]

[0171] C-5: Hydrated kaolin [Trade name: "ASP-200", manufactured by BASF (average particle size 0.4 μm)]

[0172] C-6: Precipitated barium sulfate [Trade name: "B-54", manufactured by Sakai Chemical Industry Co., Ltd. (average particle size 0.7 μm)]

[0173] C-7: Calcium carbonate [Trade name: "SCP E-#45", manufactured by Hayashi Kasei Corporation (average particle size 20.0 μm)]

[0174] C-8: Barium sulfate [trade name: "BMH-100", manufactured by Sakai Chemical Industry Co., Ltd. (average particle size 11.6 μm)].

[0175] Use the following compound as release agent D.

[0176] D-1: Triglyceride behenate total ester (trade name: "Poem TR-FB", manufactured by Riken Vitamin Co., Ltd.)

[0177] An antioxidant (trade name: "IRGANOX 1010", manufactured by BASF) is used as a stabilizer. The stabilizer is present in 0.2 parts by weight of 100 parts by weight of polyester resin A.

[0178] (Examples 1-11, Comparative Examples 1-10)

[0179] The mixtures as shown in Tables 1 and 2 were compounded using a co-rotating twin-screw extruder with the barrel temperature set at 260°C. The resulting filament was cooled with water and granulated. The resulting granules were dried at 130°C for 4 hours to obtain polyester resin compositions corresponding to the examples and comparative examples. The above-described evaluation tests (4) to (10) were performed on these polyester resin compositions.

[0180] Regarding the amount of organometallic acid salt B, in the examples and comparative examples where organometallic acid salt B was added during melt polymerization (after esterification), the residual amount (content) in the melt-blended polyester resin composition was reduced compared to the amount added (this is believed to be due to distillation during the vacuum process in the later stage of polymerization and the degassing process during melt blending). Furthermore, Comparative Example 2 (an example using polybutylene terephthalate resin a-4) did not contain organometallic acid salt B. These results are described in Tables 1 and 2 below.

[0181]

[0182]

[0183] As shown in Table 1, the polyester resin compositions of Examples 1 to 11 are consistent with the formulations specified in this application. It can be seen that there is very little mold contamination during continuous molding, and the composition has a good mirror appearance.

[0184] As shown in Table 2, Comparative Example 1 is an example where there is an excessive amount of polyethylene terephthalate resin b in polyester resin A, resulting in flow marks and a deterioration in the mirror appearance. Comparative Examples 2-4 are examples where the linear oligomer content exceeds the specified range, corresponding to at least one of the examples that do not contain organometallic acid salts B, and the molds tend to be more prone to contamination compared to the examples.

[0185] Furthermore, compared to Examples 2 and 5, which have the same composition without inorganic fillers, Comparative Example 5, which does not contain inorganic fillers, has a heat distortion temperature of 120°C, while Example 2 has a temperature of 133°C and Example 5 has a temperature of 152°C. Comparative Example 5 was evaluated as having low heat resistance. Additionally, the molding shrinkage rates of Examples 1 to 11 were 13 / 1000 to 14 / 1000, compared to 16 / 1000 for Comparative Example 5. It can be said that Comparative Example 5 has a higher probability of deformation in cases of poor demolding due to mold adhesion during injection molding, or in cases where the molded article is large or has a complex shape.

[0186] In Comparative Example 6, there was an excessive amount of inorganic filler C, which caused the filler to float out, resulting in poor appearance. In Comparative Examples 7 and 8, the average particle size of inorganic filler C was larger than the specified value, and due to poor dispersion, the mirror appearance deteriorated.

[0187] Comparative Examples 9 and 10 are examples of polyethylene terephthalate resin b being too small, with molding shrinkage rates of 16 / 1000 and 14 / 1000, respectively. It can be said that Comparative Example 9 has a higher probability of deformation in cases of poor demolding due to mold adhesion during injection molding, or in cases where the molded part is large or has a complex shape. In contrast, in Comparative Example 10, although the molding shrinkage rate was suppressed due to the increased amount of inorganic filler, the appearance deteriorated due to filler floating out.

[0188] The embodiments and examples of the present invention have been described above, but the configurations of the above embodiments and examples can also be appropriately combined.

[0189] It should be understood that the embodiments and examples disclosed herein are exemplary in all respects and not limiting. The scope of the invention is defined by the claims rather than by the foregoing description, and is intended to include all modifications with the same meaning and scope as the claims.

Claims

1. A polyester resin composition comprising polyester resin A, organometallic acid salt B of any one or both of alkali metal organometallic acid salts and alkaline earth metal organometallic acid salts, and 1 to 13 parts by weight of inorganic filler C with an average particle size of 0.05 to 3 μm relative to 100 parts by weight of said polyester resin A. The polyester resin A contains 86-88% by weight of polybutylene terephthalate resin and 12-14% by weight of polyethylene terephthalate resin. Relative to 100 parts by weight of the polyester resin A, the polyester resin composition comprises 0.000005 to 0.05 parts by weight of any one or both of alkali metal atoms and alkaline earth metal atoms, and, In the polyester resin composition, the content of polybutylene terephthalate linear oligomer, or the content of the polybutylene terephthalate linear oligomer and the polyethylene terephthalate linear oligomer, is below 1000 mg / kg. Using a mirror-finished mold polished with a ♯16000 abrasive, the polyester resin composition was injection molded at a molding temperature of 260°C, a mold temperature of 45°C, and a filling time of 4.5 seconds or more. The resulting 100mm×100mm×2mm flat plate had a maximum height roughness Rz of less than 0.70μm.

2. The polyester resin composition according to claim 1, wherein, Relative to 100 parts by weight of the polyester resin A, the polyester resin composition comprises 0.0005 to 0.05 parts by weight of either or both of the alkali metal atoms and the alkaline earth metal atoms.

3. The polyester resin composition according to claim 1 or 2, wherein, The metal in the organometallic acid salt B is selected from one or more metals in the group consisting of lithium, sodium, potassium, calcium, and magnesium.

4. The polyester resin composition according to claim 1 or 2, wherein, The organometallic acid salt B is selected from one or more of the group consisting of lithium acetate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, lithium benzoate, sodium benzoate, and potassium benzoate.

5. The polyester resin composition according to claim 1 or 2, wherein, The inorganic filler C is selected from one or more of the group consisting of calcium carbonate, silicon dioxide, kaolin and barium sulfate.

6. The polyester resin composition according to claim 3, wherein, The inorganic filler C is selected from one or more of the group consisting of calcium carbonate, silicon dioxide, kaolin and barium sulfate.

7. The polyester resin composition according to claim 4, wherein, The inorganic filler C is selected from one or more of the group consisting of calcium carbonate, silicon dioxide, kaolin and barium sulfate.

8. A component for a light reflector comprising the polyester resin composition according to any one of claims 1 to 7.

9. A light reflector having a light-reflecting metal layer formed on at least a portion of the surface of the light reflector component of claim 8.

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