Polybutylene terephthalate resin composition and molded article made therefrom

Abstract

To obtain a thermoplastic polyester resin and molded articles made therefrom that have excellent mechanical properties, moldability, low warpage, and heat resistance. [Solution] A thermoplastic polyester resin composition comprising 100 parts by mass of (A) thermoplastic polyester resin consisting of (A-1) 50 to 90 parts by mass of polybutylene terephthalate resin and (A-2) 10 to 50 parts by mass of polyethylene terephthalate resin, blended with (B) 5 to 25 parts by mass of styrene resin, (C) 10 to 50 parts by mass of glass fiber, and (D) 10 to 50 parts by mass of non-fibrous inorganic filler.

Description

Technical Field

[0001] The present invention relates to a thermoplastic polyester resin that is useful for applications such as electrical and electronic device parts, automotive parts, and machine parts, and has excellent mechanical properties, moldability, low warpage, and heat resistance, and a molded product made therefrom.

Background Art

[0002] Polybutylene terephthalate resin (hereinafter sometimes abbreviated as PBT resin) has been developed for applications such as electrical and electronic device parts, automotive parts, and machine and mechanism parts because of its excellent mechanical properties, electrical properties, and chemical resistance.

[0003] In particular, in recent years, in PBT resins used for in-vehicle applications, from the viewpoints of an increase in information communication device parts used in next-generation in-vehicle (EV / HEV) advanced driver assistance systems and ensuring reliability, molded products with good low warpage are required. Furthermore, in order to secure the in-vehicle space, the use environment temperature of PBT resins associated with space saving is rising, and it is required to have high heat resistance.

[0004] However, since PBT resin has high crystallinity among engineering plastics, in molded products such as box-shaped shapes, the warpage is large and the dimensional stability is not sufficient.

[0005] Furthermore, in recent years, the demand for recycling resin compositions for a decarbonized society has been increasing. It is also required to reduce waste by recycling resin products discarded due to factors such as out-of-specification in the production process and recycled resins recovered from products discarded after being used as predetermined products and remolding them into resin products again.

[0006] To date, methods for imparting low warpage to polybutylene terephthalate resin have been known, including alloying it with a resin different from polybutylene terephthalate resin and adding inorganic fillers. Examples of such resin compositions include a thermoplastic resin composition (Patent Document 1) obtained by polymerizing polybutylene terephthalate resin with polyethylene terephthalate resin, a thermoplastic resin obtained by polymerizing at least one monomer selected from aromatic vinyl compounds, vinyl cyanide compounds, and (meth)acrylate alkyl esters, and an inorganic filler; a polyester resin composition (Patent Document 1) obtained by compounding polybutylene terephthalate resin with styrene-based resin, a fibrous inorganic filler, and a plate-like inorganic material; a polyester resin composition (Patent Document 2) obtained by compounding polybutylene terephthalate resin with polyethylene terephthalate resin and a fibrous inorganic filler; and a polyethylene terephthalate resin composition (Patent Document 3) obtained by compounding polybutylene terephthalate resin with polycarbonate resin or polyethylene terephthalate resin, an impact resistance modifier, and an inorganic filler. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-100765 [Patent Document 2] Japanese Patent Application Publication No. 10-60242 [Patent Document 3] Japanese Patent Publication No. 2023-81361 [Patent Document 4] Japanese Patent Publication No. 2001-234046 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in Patent Document 1, a large amount of styrene-based resin component was incorporated, resulting in insufficient heat resistance. In Patent Document 2, in addition to insufficient heat resistance due to a large amount of styrene-based resin, the high amount of inorganic filler resulted in poor moldability. In Patent Document 3, the low amount of inorganic filler may have resulted in insufficient mechanical properties and low warpage. In Patent Document 4, the incorporation of thermoplastic elastomer resin resulted in insufficient low warpage and heat resistance.

[0009] The present invention aims to provide a thermoplastic polyester resin and molded articles made therefrom that are useful for applications such as electrical and electronic equipment components, automotive parts, and machine parts, and that have excellent mechanical properties, moldability, low warpage, and heat resistance. Furthermore, it aims to provide a thermoplastic polyester resin composition and molded articles made therefrom that have high quality even when recycled polyester resin is used. [Means for solving the problem]

[0010] As a result of repeated studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by blending (A) a thermoplastic polyester resin consisting of (A-1) polybutylene terephthalate resin and (A-2) polyethylene terephthalate resin, (B) a styrene-based resin, (C) glass fiber, and (D) a non-fibrous inorganic filler in specific amounts, and have arrived at the present invention. That is, the present invention has the following configuration.

[0011] 1. A thermoplastic polyester resin composition comprising 100 parts by mass of (A) thermoplastic polyester resin consisting of 50 to 90 parts by mass of (A-1) polybutylene terephthalate resin and 10 to 50 parts by mass of (A-2) polyethylene terephthalate resin, blended with (B) 5 to 25 parts by mass of styrene resin, (C) 10 to 50 parts by mass of glass fiber, and (D) 10 to 50 parts by mass of non-fibrous inorganic filler.

[0012] 2.(B) The thermoplastic polyester resin composition according to claim 1, characterized in that the styrene resin comprises at least one styrene resin selected from styrene / acrylonitrile copolymer, styrene / butadiene / acrylonitrile copolymer, and glycidyl methacrylate / styrene / acrylonitrile copolymer.

[0013] 3. (D) The thermoplastic polyester resin composition according to item 1 or 2, characterized in that the non-fibrous inorganic filler is glass flakes.

[0014] 4. (B) A thermoplastic polyester resin composition according to items 1 to 3, characterized in that the styrene resin comprises at least one styrene resin selected from styrene / acrylonitrile copolymer and glycidyl methacrylate / styrene / acrylonitrile copolymer.

[0015] 5. (A-2) A thermoplastic polyester resin composition according to any one of items 1 to 4, characterized in that the polyethylene terephthalate resin is recycled polyethylene terephthalate resin.

[0016] 6. A thermoplastic polyester resin composition according to any one of items 1 to 5, comprising 100 parts by mass of (A) thermoplastic polyester resin and further 0.01 to 5.0 parts by mass of (E) aliphatic alkyl acid phosphate.

[0017] 7. (C) A thermoplastic polyester resin composition according to any one of items 1 to 6, wherein the ratio of the major axis (longest straight distance of the cross-section) to the minor axis (longest straight distance perpendicular to the major axis) of the cross-section perpendicular to the length direction of the glass fiber is 1.3 to 10.0.

[0018] A molded article made of a thermoplastic polyester resin as described in any of sections 8.1 to 8.7. [Effects of the Invention]

[0019] According to the polybutylene terephthalate resin composition of the present invention, molded articles excellent in mechanical properties, moldability, low warpage property, and heat resistance can be obtained. Further, by using recycled polyethylene terephthalate resin, not only is it excellent in moldability and heat resistance, but the energy consumption for production raw materials can be reduced, and the carbon dioxide emission can be reduced.

Brief Description of the Drawings

[0020] [Figure 1] Appearance of box-shaped molded articles for measuring warpage amount in small boxes in Examples and Comparative Examples [Figure 2] Schematic side view (1) and schematic plan view (2) of FIG. 1

Modes for Carrying Out the Invention

[0021] Next, the polybutylene terephthalate resin composition of the present invention will be described in detail.

[0022] The thermoplastic polyester resin composition of the present invention is based on 100 parts by mass of (A) thermoplastic polyester resin composed of 50 to 90 parts by mass of (A-1) polybutylene terephthalate resin and 10 to 50 parts by mass of (A-2) polyethylene terephthalate resin, and (B) 5 to 25 parts by mass of styrene resin, (C) 10 to 50 parts by mass of glass fiber, and (D) 10 to 50 parts by mass of non-fibrous inorganic filler are blended.

[0023] Although polybutylene terephthalate resin has excellent electrical properties and chemical resistance, it tends to solidify during cooling after injection molding. In particular, in box-shaped molded products, the internal temperature of the molded product in the mold becomes high, promoting crystallization, which causes inward warping and makes the molded product unsuitable. Furthermore, significant shrinkage due to crystallization leads to poor release from the mold and cracking of the molded product during release. In the present invention, by blending (A-1) polybutylene terephthalate resin 50 to 90 parts by mass and (A-2) polyethylene terephthalate resin 10 to 50 parts by mass with (A) thermoplastic polyester resin 100 parts by mass, the structure of the thermoplastic polyester resin is disrupted, making it possible to reduce the cooling and solidification rate during molding and suppress crystallization of the thermoplastic polyester resin, resulting in good moldability and low warping. Furthermore, by blending (B) styrene-based resin, which has excellent heat resistance among amorphous resins, high heat resistance, low warping, and high fluidity can be obtained.

[0024] While glass fibers are commonly used to improve the mechanical properties and dimensional stability of polybutylene terephthalate resin, glass fibers exhibit high anisotropy. In particular, in molded products with box-like shapes, the large difference in shrinkage rates between the resin flow direction and the direction perpendicular to the flow direction leads to significant warping, making the product unsuitable. Furthermore, glass fibers have large fiber diameters and lengths, resulting in poor fluidity during molding and making molding difficult. In this invention, by incorporating (D) a non-fibrous inorganic filler in addition to (C) glass fibers as an inorganic filler, it is possible to obtain a molded product with excellent fluidity and low warping due to low anisotropy.

[0025] (A) Thermoplastic polyester resin The thermoplastic polyester resin (A) used in the present invention is a polymer or copolymer having at least one residue selected from the group consisting of (1) dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative, (2) hydroxycarboxylic acid or its ester-forming derivative, and (3) lactone as the main structural unit. Here, "having as the main structural unit" means having at least 50 mol% or more of at least one residue selected from the group consisting of (1) to (3) in the total structural units, and it is preferable that these residues constitute 80 mol% or more. Among these, polymers or copolymers having residues of (1) dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative as the main structural unit are preferred in terms of superior injection moldability and mechanical properties.

[0026] Examples of the above-mentioned dicarboxylic acids or their ester-forming derivatives include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyl etherdicarboxylic acid, 5-tetrabutylphosphonium isophthalic acid, and 5-sodium sulfisoisophthalic acid; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedionic acid, malonic acid, glutaric acid, and dimer acid; alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, and their ester-forming derivatives. Two or more of these may be used.

[0027] Examples of the above-mentioned diols or their ester-forming derivatives include aliphatic or alicyclic glycols having 2 to 20 carbon atoms, such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, and dimergol; long-chain glycols with molecular weights of 200 to 100,000, such as polyethylene glycol, poly-1,3-propylene glycol, and polytetramethylene glycol; aromatic dioxy compounds such as 4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, bisphenol A, bisphenol S, and bisphenol F; and ester-forming derivatives thereof. Two or more of these may be used.

[0028] Polymers or copolymers having dicarboxylic acids or their ester-forming derivatives and diols or their ester-forming derivatives as structural units include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene isophthalate, polybutylene isophthalate, polybutylene naphthalate, polypropylene isophthalate / terephthalate, polybutylene isophthalate / terephthalate, polypropylene terephthalate / naphthalate, polybutylene terephthalate / naphthalate, polybutylene terephthalate / decanedicarboxylate, polypropylene terephthalate / 5-sodium sulfoisophthalate, polybutylene terephthalate / 5-sodium sulfoisophthalate, polypropylene terephthalate / polyethylene glycol, polybutylene terephthalate / polyethylene Examples include aromatic polyester resins such as polybutylene glycol, polypropylene terephthalate / polytetramethylene glycol, polybutylene terephthalate / polytetramethylene glycol, polypropylene terephthalate / isophthalate / polytetramethylene glycol, polybutylene terephthalate / isophthalate / polytetramethylene glycol, polybutylene terephthalate / succinate, polypropylene terephthalate / adipate, polybutylene terephthalate / adipate, polypropylene terephthalate / sevacate, polybutylene terephthalate / sevacate, polypropylene terephthalate / isophthalate / adipate, polybutylene terephthalate / isophthalate / succinate, polybutylene terephthalate / isophthalate / adipate, and polybutylene terephthalate / isophthalate / sevacate. These polymers and copolymers may be used individually or in combination of two or more. Here, " / " represents a copolymer.

[0029] Among these, polymers or copolymers having residues of aromatic dicarboxylic acids or their ester-forming derivatives and residues of aliphatic diols or their ester-forming derivatives as the main structural units are more preferred from the viewpoint of injection moldability and mechanical properties, and polymers or copolymers having residues of terephthalic acid, naphthalenedicarboxylic acid or its ester-forming derivative and residues of aliphatic diols selected from ethylene glycol, propylene glycol, and 1,4-butanediol or their ester-forming derivatives as the main structural units are even more preferred.

[0030] Among these, at least one aromatic polyester resin selected from polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene naphthalate, polybutylene naphthalate, polypropylene isophthalate / terephthalate, polybutylene isophthalate / terephthalate, polypropylene terephthalate / naphthalate, polybutylene adipate / terephthalate, polybutylene terephthalate / sevacate, and polybutylene terephthalate / naphthalate is particularly preferred, and at least one selected from polyethylene terephthalate, polybutylene terephthalate, polybutylene isophthalate / terephthalate, polybutylene decanedicarboxylate / terephthalate, polybutylene terephthalate / naphthalate, and polybutylene / ethylene terephthalate is more preferred.

[0031] The thermoplastic polyester resin (A) used in the present invention is formulated by blending 50 to 90 parts by mass of (A-1) polybutylene terephthalate resin and 10 to 50 parts by mass or less of (A-2) polyethylene terephthalate resin in 100 parts by mass of thermoplastic polyester resin (A) in order to improve mechanical properties, crystallization control during molding, and hydrolysis resistance. The amount of (A-1) polybutylene terephthalate resin blended is preferably 90 parts by mass or less in order to obtain high levels of low warpage, and more preferably 85 parts by mass or less. The amount of (A-2) polyethylene terephthalate resin blended is preferably 10 parts by mass or more in order to obtain high levels of low warpage, and more preferably 15 parts by mass or more. If the amount of (A-1) polybutylene terephthalate resin is less than 50 parts by mass, the solidification characteristics during molding and cooling decrease, resulting in a significant decrease in productivity, as well as poor fluidity during injection molding. (A-1) When the amount of polybutylene terephthalate resin exceeds 90 parts by mass, shrinkage of the molded product due to crystallization not only results in poor warpage but also poor release from the mold, and productivity deteriorates significantly.

[0032] The (A-1) polybutylene terephthalate resin used in the present invention is a polymer obtained by polymerization methods such as polycondensation reaction, with terephthalic acid or its ester-forming derivative and 1,4-butanediol or its ester-forming derivative as the main components. Here, "main components" means that for each of the dicarboxylic acid component and the diol component, 50 mol% or more are terephthalic acid or its ester-forming derivative and 1,4-butanediol or its ester-forming derivative. Furthermore, other copolymer components may be included in a range that does not impair the properties, for example, in a range of about 20 mol% or less in the raw materials. Preferred examples of these polymers and copolymers include polybutylene terephthalate, polybutylene (terephthalate / isophthalate), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene (terephthalate / naphthalate), and poly(butylene / ethylene) terephthalate, which may be used individually or in combination of two or more.

[0033] The (A-1) polybutylene terephthalate resin used in this invention is preferable in terms of fluidity if its melt flow rate (MFR) measured at 250°C and 1000 gf is 1 g / 10 min or more, and more preferably 10 g / 10 min or more. If it is 75 g / 10 min or less, it is preferable in terms of mechanical properties, and more preferably 60 g / 10 min or less.

[0034] The method for producing the (A-1) polybutylene terephthalate resin used in the present invention is not particularly limited, and known polycondensation methods and ring-opening polymerization methods can be used. Either batch polymerization or continuous polymerization methods may be used, and methods involving transesterification and polycondensation reactions, as well as methods involving polycondensation reactions by direct polymerization (direct polymerization method), can all be applied. Direct polymerization is preferred because it allows for easy control of the amount of carboxyl terminal groups and is economical. It is preferable to add a catalyst during the esterification or transesterification reaction and polycondensation reaction in order to effectively advance these reactions. Specific examples of catalysts include organotitanium compounds such as methyl esters of titanate, tetra-n-propyl esters, tetra-n-butyl esters, tetraisopropyl esters, tetraisobutyl esters, tetra-tert-butyl esters, cyclohexyl esters, phenyl esters, benzyl esters, tolyl esters, or mixed esters thereof, dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethyldistin oxide, cyclohexahexyldistin oxide, didodecyltin oxide, and triethyltin hydroxide. Examples of catalysts include tin compounds such as nitrate, triphenyltin hydroxide, triisobutyltin acetate, dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, alkyl stannon acids such as methyl stannon acid, ethyl stannon acid, and butyl stannon acid, zirconia compounds such as zirconium tetra-n-butoxide, and antimony compounds such as antimony trioxide and antimony acetate. Two or more of these catalysts can also be used in combination. From the viewpoint of the carboxyl group concentration of (A-1) polybutylene terephthalate resin, organotitanium compounds and tin compounds are preferred among these polymerization catalysts, and tetra-n-butyl ester of titanic acid is even more preferred. The amount of polymerization catalyst blended is preferably in the range of 0.01 to 0.2 parts by mass per 100 parts by mass of (A-1) polybutylene terephthalate resin.

[0035] The (A-2) polyethylene terephthalate resin used in the present invention is a polymer obtained by a polymerization reaction such as polycondensation, with terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative as the main components. Here, "main components" means that 50 mol% or more of the dicarboxylic acid component and the diol component are terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative. Other copolymer components may also be included in a range that does not impair the properties, for example, in a range of about 20 mol% or less of the raw materials. Here, "main components" means that, independently, the dicarboxylic acid component and the diol component each occupy more than 50 parts by mass of their respective components. Preferred examples of these polymers and copolymers include polyethylene terephthalate, polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sebacate), polyethylene (terephthalate / decanedicarboxylate), polyethylene (terephthalate / naphthalate), etc., which may be used individually or in combination of two or more.

[0036] The polyethylene terephthalate resin (A-2) used in the present invention is preferable in terms of fluidity if its melt flow rate (MFR) measured at 275°C and 325 gf is 1 g / 10 min or more, and more preferably 5 g / 10 min or more. If it is 50 g / 10 min or less, it is preferable in terms of mechanical properties, and more preferably 45 g / 10 min or less.

[0037] The method for producing the (A-2) polyethylene terephthalate resin used in the present invention is not particularly limited, and known polycondensation methods and ring-opening polymerization methods can be used. Either batch polymerization or continuous polymerization methods may be used, and methods involving transesterification and polycondensation reactions, as well as methods involving polycondensation reactions by direct polymerization (direct polymerization method), can all be applied. Direct polymerization is preferred because it allows for easy control of the amount of carboxyl terminal groups and is economical. It is preferable to add a catalyst during the esterification or transesterification reaction and polycondensation reaction in order to effectively advance these reactions. Specific examples of catalysts include organotitanium compounds such as methyl esters of titanate, tetra-n-propyl esters, tetra-n-butyl esters, tetraisopropyl esters, tetraisobutyl esters, tetra-tert-butyl esters, cyclohexyl esters, phenyl esters, benzyl esters, tolyl esters, or mixed esters thereof, dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethyldistin oxide, cyclohexahexyldistin oxide, didodecyltin oxide, and triethyltin hydroxide. Examples of catalysts include tin compounds such as triphenyltin hydroxide, triisobutyltin acetate, dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, alkyl stannon acids such as methyl stannon acid, ethyl stannon acid, and butyl stannon acid, zirconia compounds such as zirconium tetra-n-butoxide, and antimony compounds such as antimony trioxide and antimony acetate. Two or more of these catalysts can also be used in combination. (A-2) From the viewpoint of carboxyl group concentration in polyethylene terephthalate resin, organotitanium compounds and tin compounds are preferred among these polymerization catalysts, and tetra-n-butyl ester of titanic acid is even more preferred. The amount of polymerization catalyst blended is preferably in the range of 0.01 to 0.2 parts by mass per 100 parts by mass of polyethylene terephthalate resin.

[0038] In the present invention, (A-2) polyethylene terephthalate resin may be virgin polyethylene terephthalate resin, but from the viewpoint of reducing waste and carbon dioxide emissions, recycled polyethylene terephthalate resin is more preferable. Virgin polyethylene terephthalate resin refers to polyethylene terephthalate resin obtained by polymerization reaction from raw material monomers and which has never been recycled. Recycled polyethylene terephthalate resins include post-industrial recycled materials obtained from off-spec products in the manufacturing process, and post-consumer recycled materials obtained by recovering resin products using polyethylene terephthalate resin that are distributed in the market. One or both of these can be used in any proportion.

[0039] The recycled polyethylene terephthalate resin, which is referred to as a post-industrial recycled material or post-consumer recycled material in this invention, includes, for example, off-spec pellets generated during the manufacture of polyethylene terephthalate resin, off-spec products during the manufacture of resin products such as bottles, films, fibers, and injection-molded products, and pre-consumer products such as sprues, runners, and lumps generated during molding and processing, as well as post-consumer recycled products obtained by recovering products containing polyethylene terephthalate resin from the market, chemical recycled products obtained by depolymerizing resin products containing polyethylene terephthalate resin recovered from the market to decompose the polyethylene terephthalate resin and then repolymerizing it, flake-shaped recycled products obtained by crushing recovered polyethylene terephthalate resin, and pellet-shaped recycled products obtained by cutting molten resin that is extruded from a nozzle after heating and melting during the manufacture of a resin composition containing polyethylene terephthalate resin. By reusing polyethylene terephthalate resin that would have been conventionally discarded, recycled polyethylene terephthalate resin can reduce the energy consumption used in the manufacturing and disposal processes and reduce carbon dioxide emissions compared to virgin polyethylene terephthalate resin.

[0040] It is even more preferable to use material-recycled polyethylene terephthalate resin as the (A-2) polyethylene terephthalate resin used in the present invention. Material-recycled polyethylene terephthalate resin not only reduces carbon dioxide emissions, but also undergoes a greater thermal history during molding, which improves the fluidity of the resulting thermoplastic polyester resin. In addition, by lowering the injection pressure during molding, damage to the inorganic filler is suppressed, and mechanical properties and heat resistance are improved.

[0041] The (A-2) polyethylene terephthalate resin used in the present invention may contain components other than polyethylene terephthalate resin, as long as they do not affect the properties of the polyester resin of the present invention. Examples of components other than polyethylene terephthalate resin include, for example, stabilizers, weathering agents, lubricants, pigments, dyes, nucleating agents, plasticizers, antistatic agents, flame retardants, color inhibitors, inorganic fillers such as fibrous reinforcing materials, and other polymers other than polyethylene terephthalate resin.

[0042] (B) Styrene resin The (B) styrene-based resin used in the thermoplastic polyester resin composition of the present invention can be any (co)polymer having structural units derived from styrene, but a (co)polymer obtained by polymerizing a styrene-based compound, or a styrene-based compound with another compound copolymerizable with a styrene-based compound, is preferred, and may also contain a rubber component.

[0043] Specific examples of styrene compounds include styrene, methylstyrene, dimethylstyrene, ethylstyrene, and butylstyrene. Two or more of these may be used.

[0044] Specific examples of other compounds copolymerizable with styrene compounds include acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and glycidyl methacrylate; and unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile. Two or more of these may be combined.

[0045] Suitable rubber components include diene-based rubber and ethylene-based rubber. Specific examples of rubber components include polybutadiene, polyisoprene, ethylene / propylene rubber, ethylene / propylene / diene rubber, and poly(ethylene / isoprene). Of these rubber components, polybutadiene is preferred.

[0046] Specific examples of the (B) styrene-based resin used in the present invention include polystyrene, HI (high-impact) polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / styrene / glycidyl methacrylate copolymer, acrylonitrile / butadiene / styrene copolymer, and acrylonitrile / ethylene rubber / styrene copolymer. Among these, acrylonitrile / styrene copolymer, acrylonitrile / styrene / glycidyl methacrylate copolymer, and acrylonitrile / butadiene / styrene copolymer are preferred from the viewpoint of low warping, and acrylonitrile / styrene copolymer and acrylonitrile / styrene / glycidyl methacrylate copolymer are more preferred from the viewpoint of heat resistance.

[0047] In the present invention, the amount of (B) styrene resin blended is 5 to 25 parts by mass per 100 parts by mass of the (A) thermoplastic polyester resin. If the amount of styrene resin blended is less than 5 parts by mass, it is undesirable in terms of low warpage and fluidity. More preferably, it is 7 parts by mass or more, and even more preferably 10 parts by mass or more. If the amount of styrene resin blended exceeds 25 parts by mass, not only does the heat resistance decrease, but the solidification of the molded product is suppressed, the release properties from the mold decrease, and productivity decreases significantly.

[0048] (C) Glass fiber The (C) glass fibers used in the present invention are selected from glass compositions such as A glass, C glass, E glass, R glass, D glass, M glass, and S glass, with E glass being particularly preferred. The (C) glass fibers are chopped strand or roving type glass fibers commonly used as reinforcing materials for PBT resins, and glass fibers treated with a silane coupling agent such as an aminosilane compound or an epoxysilane compound and / or a consolidator containing one or more epoxy compounds such as urethane, vinyl acetate, bisphenol A diglycidyl ether, or novolac-type epoxy compounds are preferably used. Furthermore, the above-mentioned silane coupling agent and / or consolidator may be used in the form of an emulsion liquid.

[0049] The (C) glass fibers used in the present invention preferably have a fiber diameter of 1 to 15 μm. A diameter of 1 μm or more is preferable in terms of fluidity, more preferably 3 μm, and even more preferably 6 μm. A diameter of 15 μm or less is preferable in terms of mechanical properties, more preferably 14 μm, and even more preferably 13 μm.

[0050] The amount of (C) glass fiber used in the present invention is characterized by being 10 to 50 parts by mass per 100 parts by mass of the (A) thermoplastic polyester resin. If it is less than 10 parts by mass, it is undesirable in terms of mechanical properties and heat resistance. More preferably it is 15 parts by mass or more, and even more preferably 20 parts by mass or more. If it exceeds 50 parts by mass, it is undesirable in terms of fluidity and productivity. More preferably it is 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0051] Furthermore, although the fiber cross-section of the glass fiber (C) is usually circular, fibrous reinforcing materials with arbitrary cross-sections, such as elliptical glass fibers with arbitrary aspect ratios, flattened glass fibers, and cocoon-shaped glass fibers, can also be used, which has the advantage of improving fluidity during injection molding and producing molded products with less warping.

[0052] In the cross-section of the (C) glass fiber used in the present invention, the ratio of the major axis (longest straight distance in the cross-section) to the minor axis (longest straight distance perpendicular to the major axis) is preferably 1.3 or more in terms of low warping, and more preferably 3.0 or more. It is preferably 10.0 or less in terms of mechanical properties, more preferably 8.0 or less, and even more preferably 7.0 or less.

[0053] (D) Non-fibrous inorganic filler The amount of (D) non-fibrous inorganic filler in the present invention is characterized by being 10 to 50 parts by mass per 100 parts by mass of the thermoplastic polyester resin (A). If it is less than 10 parts by mass, it is undesirable in terms of low warpage. More preferably it is 15 parts by mass or more, and even more preferably 20 parts by mass or more. If it exceeds 50 parts by mass, it is undesirable in terms of mechanical properties and fluidity. More preferably it is 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0054] By incorporating (D) non-fibrous inorganic fillers into the thermoplastic polyester resin composition of the present invention, the warpage of molded articles can be improved. Examples of (D) non-fibrous inorganic fillers used in the present invention include mica, talc, kaolin, silica, calcium carbonate, glass beads, glass flakes, glass microballoons, clay, molybdenum disulfide, wollastonite, montmorillonite, titanium dioxide, zinc oxide, calcium polyphosphate, graphite, and barium sulfate, which may be used individually or in combination of two or more. From the viewpoint of low warpage, glass flakes and glass beads are preferred, and from the viewpoint of mechanical properties, fluidity, and heat resistance, glass flakes are more preferred.

[0055] The average particle size of the (D) non-fibrous inorganic filler used in the present invention is preferably 10 μm or more in terms of mechanical properties and heat resistance, more preferably 15 μm or more, and even more preferably 20 μm or more. If it is 800 μm or less, it is preferable in terms of fluidity and productivity, more preferably 750 μm or less, and even more preferably 700 μm or less.

[0056] (E) Aliphatic alkyl acid phosphate The (E) aliphatic alkyl acid phosphate used in this invention has the effect of suppressing the detachment of the aliphatic alcohol moiety of the (A) thermoplastic polyester resin by transesterification, thereby improving stability during melt retention.

[0057] In the thermoplastic polyester resin composition of the present invention, the amount of (E) aliphatic alkyl acid phosphate is preferably 0.01 to 5.00 parts by mass per 100 parts by mass of (A) thermoplastic polyester resin. More preferably, the amount is 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, in terms of melt retention stability. If the amount is 5.00 parts by mass or less, it is preferable in terms of mechanical properties, and more preferably 1.00 part by mass or less.

[0058] The (E) aliphatic alkyl acid phosphate used in this invention includes, for example, methyl acid phosphate, ethyl acid phosphate, propyl acid phosphate, butyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate, decyl acid phosphate, dodecyl acid phosphate, and octadecyl acid phosphate. A mixture containing one or more of these may also be used. Octadecyl acid phosphate is a particularly preferred (E) aliphatic alkyl acid phosphate. By using (E) aliphatic alkyl acid phosphate, viscosity changes during the melting of thermoplastic polyester resin during injection molding can be suppressed.

[0059] [Other ingredients] The thermoplastic polyester resin composition of the present invention may contain other resin components, flame retardants, stabilizers, nucleating agents, colorants, lubricants, and other common additives, as long as they do not impair the effects of the present invention. Two or more of these may be included.

[0060] Other resin components can be any resin that can be melt-molded, such as polyethylene resin, polypropylene resin, polymethylpentene resin, cyclic olefin resin, cellulose resin such as cellulose acetate, polyamide resin, polyacetal resin, polysulfone resin, polyphenylene sulfide resin, polyetheretherketone resin, polyimide resin, and polyetherimide resin.

[0061] Any flame retardant used in polyester resin compositions can be used as the flame retardant. For example, examples include high molecular weight organic halogen compounds such as organic halogen-based flame retardants, specifically halogenated acrylic resins, halogenated epoxy resins, halogenated phenoxy resins, halogenated polystyrenes, tetrabromobisphenol A ethyl ether oligomers, and halogenated polyphenylene ethers (e.g., polydibromophenylene oxide); and low molecular weight organic halogen compounds such as decabromodiphenyl ether, hexabromophenol, tetrabromobisphenol A bis(2,3-dibromopropyl ether), tetrabromobisphenol A bis(allyl ether), tetrabromobisphenol A 2-hydroxyethyl ether, hexabromobenzene, tetrabromophthalic anhydride, tribromophenol, bis(tribromophenoxy)ethane, bis(pentabromophenoxy)ethane, ethylenebistetrabromophthalimide, brominated styrene, tetrabromobisphenol S, and bis(2,3-dibromopropyl ether) of tetrabromobisphenol S. These organic halogen-based flame retardants may be used individually or in combination of two or more. Furthermore, phosphorus-based (different from (E) aliphatic alkyl acid phosphates), inorganic flame retardants, and other types can also be used.

[0062] Any stabilizer used in polyester resin compositions can be used. Examples include antioxidants, light stabilizers, and catalyst deactivators. Two or more of these may be blended together.

[0063] Examples of colorants include organic dyes, organic pigments, and inorganic pigments. Two or more of these may be combined.

[0064] Examples of lubricants include, but are not limited to, metal soaps such as calcium stearate and barium stearate, fatty acid esters, salts of fatty acid esters (including those partially converted to salts), fatty acid amides such as ethylenebisstearamide, fatty acid amides consisting of polycondensates of ethylenediamine, stearic acid, and sebacic acid, or polycondensates of phenylenediamine, stearic acid, and sebacic acid, polyalkylene waxes, acid anhydride-modified polyalkylene waxes, and mixtures of the above lubricants with fluorine-based resins or fluorine-based compounds.

[0065] The thermoplastic polyester resin composition of the present invention preferably contains a uniform dispersion of (A) thermoplastic polyester resin, (B) styrene resin, (C) glass fibers, and (D) non-fibrous inorganic filler, and optionally (E) aliphatic alkyl acid phosphate and other components. A method for producing the thermoplastic polyester resin composition of the present invention includes, for example, a method of melt-kneading each component 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 also be mixed together beforehand and then melt-kneaded. It is preferable that the moisture content of each component is low, and if necessary, they should be dried beforehand.

[0066] Furthermore, as a method for introducing each component into a melting and mixing machine, for example, a single-screw or twin-screw extruder is used, and (A) thermoplastic polyester resin and (B) styrene resin, as well as (E) aliphatic alkyl acid phosphate and other components as needed, are supplied from a main inlet installed on the screw root side, and (C) glass fibers and (D) non-fibrous inorganic filler are supplied from a secondary inlet installed between the main inlet and the tip of the extruder, and then melted and mixed.

[0067] The melting and kneading temperature is preferably 190°C or higher in terms of fluidity, more preferably 210°C or higher, and even more preferably 240°C or higher. If the temperature is 340°C or lower, it is preferable in terms of mechanical properties, more preferably 330°C or lower, and even more preferably 320°C or lower.

[0068] The resin composition of the present invention can be molded by any of the commonly known methods such as injection molding, extrusion molding, blow molding, press molding, and spinning, and can be processed and used in various molded products. As molded products, it can be used as injection molded products, extruded products, blow molded products, films, sheets, fibers, etc. As films, it can be used as various types of films such as undrawn, uniaxially drawn, and biaxially drawn films, and as fibers, it can be used as various types of fibers such as undrawn yarn, drawn yarn, and super-drawn yarn.

[0069] In the present invention, the above-mentioned molded articles can be used for a variety of applications, including automotive parts, electrical and electronic components, building materials, various containers, daily necessities, household goods, and hygiene products. In particular, the thermoplastic polyester resin composition of the present invention is particularly suitable as a box-shaped molded article for information and communication equipment components in automobiles due to its excellent fluidity, low warping, and geothermal properties. Furthermore, the thermoplastic polyester resin composition of the present invention has excellent fluidity, suppresses glass fiber breakage after molding, and suppresses the deterioration of mechanical properties of recycled products, so molded articles for various applications can be further recycled and circulated for use as various molded articles. [Examples]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The raw materials used in each example and comparative example are shown below.

[0071] (A) Thermoplastic polyester resin A-1-1: Polybutylene terephthalate (manufactured by Toray Industries, Inc., "Toraycon" (registered trademark), MFR: 35g / 10 min (250℃, 1000gf)). A-2-1: Virgin polyethylene terephthalate (manufactured by Toray Industries, Inc., MFR: 9g / 10 min (275℃, 325gf)). A-2-2: Recycled polyethylene terephthalate (manufactured by Toray Industries, Inc., material recycled material, MFR: 36g / 10 min (275℃, 325gf)).

[0072] (B) Styrene resin B-1: Acrylonitrile / styrene copolymer The mass ratio of each component in the acrylonitrile / styrene copolymer, prepared by suspension polymerization of styrene and acrylonitrile, is acrylonitrile:styrene = 28:72. B-2: Acrylonitrile / butadiene / styrene copolymer 40 parts by mass of a monomer mixture consisting of 70% by mass of styrene and 30% by mass of acrylonitrile was emulsion polymerized in the presence of 60 parts by mass of polybutadiene latex (rubber particle size 0.25 μm) (calculated on a fixed-rate basis). The resulting graft copolymer was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered, and dried to prepare a powdered graft copolymer. The mass ratio of each component in the acrylonitrile / butadiene / styrene copolymer is acrylonitrile:butadiene:styrene = 12:60:28. B-3: Acrylonitrile / styrene / glycidyl methacrylate copolymer A bead-like copolymer was prepared by suspension polymerization of styrene, acrylonitrile, and glycidyl methacrylate. The mass ratio of each component in the acrylonitrile / styrene / glycidyl methacrylate copolymer was acrylonitrile:styrene:glycidyl methacrylate = 23.9:75.8:0.3.

[0073] (C) Glass fiber C-1: Flattened cross-section chopped glass fiber (manufactured by Nitto Boseki Co., Ltd., "CSG 3PA-830", ratio of major axis to minor axis of cross-section is 4.0, major axis: 28 μm, minor axis: 7 μm). C-2: Circular cross-section chopped glass fiber (manufactured by Nippon Electric Glass Co., Ltd., "T-158H", ratio of major axis to minor axis of cross-section is 1.0, fiber diameter: 10 μm). C-3: Circular cross-section chopped glass fiber (manufactured by Nippon Electric Glass Co., Ltd., "T-187", ratio of major axis to minor axis of cross-section is 1.0, fiber diameter: 13 μm).

[0074] (D) Non-fibrous inorganic filler D-1: Glass flakes (manufactured by Nippon Sheet Glass Co., Ltd., Microglass Flexa REFG-101, average particle size: 600 μm, average thickness: 5 μm). D-2: Glass flakes (manufactured by Nippon Sheet Glass Co., Ltd., Microglass Fleca REFG-301, average particle size: 160 μm, average thickness: 5 μm). D-3: Glass beads (manufactured by Potters Barotini Co., Ltd., GB731B2, average particle size: 32 μm).

[0075] (E) Aliphatic alkyl acid phosphate E-1: Octadecyl acid phosphate (manufactured by ADEKA Corporation, "ADEKA Stub" (registered trademark) AX-71).

[0076] (F)(B) Amorphous resins excluding styrene-based resins F: Polycarbonate resin (manufactured by Mitsubishi Chemical Corporation, "Yupilon" (registered trademark) H-2000).

[0077] The evaluation methods used in the examples and comparative examples are summarized below.

[0078] (1) Tensile strength and tensile strain The pellets obtained in each example and comparative example were dried in a hot air dryer at 130°C for 3 hours. Then, multi-purpose test specimens of type A1 as specified in JIS K7139 were prepared using a Sumitomo Heavy Industries, Ltd. "SE50DUZ" injection molding machine under molding conditions of cylinder temperature 260°C and mold temperature 80°C, and the tensile strength and tensile strain were determined according to ISO 527-1 and -2.

[0079] (2) Bending strength, bending modulus The pellets obtained in each example and comparative example were dried in a hot air dryer at 130°C for 3 hours. Then, multi-purpose test specimens of type A1 as specified in JIS K7139 were prepared using a Sumitomo Heavy Industries, Ltd. "SE50DUZ" injection molding machine under molding conditions of cylinder temperature 260°C and mold temperature 80°C, and the bending strength and bending modulus were determined according to ISO 178.

[0080] (3) Notched Charpy impact strength The pellets obtained in each example and comparative example were dried in a hot air dryer at 130°C for 3 hours. Then, multi-purpose test specimens of type A1 as specified in JIS K7139 were prepared using a Sumitomo Heavy Industries, Ltd. "SE50DUZ" injection molding machine under molding conditions of cylinder temperature 260°C and mold temperature 80°C, and the notched Charpy impact strength was determined according to ISO 179.

[0081] (4) Warping inside the small box After drying the pellets obtained in each example and comparative example in a hot air dryer at 130°C for 3 hours, small box molded products (30 mm wide x 30 mm deep x 30 mm high, 1.5 mm thick) with the openings shown in Figures 1 and 2 were molded from the side pin gate using a Sumitomo Heavy Industries, Ltd. "SE50DUZ" injection molding machine under molding conditions of cylinder temperature 260°C, mold temperature 80°C, and cooling time 10 seconds. After being left in a 23°C x 50% RH atmosphere for 24 hours, the amount of inward tilt of the side surface on the non-gate side was measured using a Mitutoyo 3D dimension measuring machine (CRYSTA-Apex S776), and the average value of 10 molded products was defined as the internal warpage of the small box. A smaller internal warpage value indicates better low warpage. An internal warpage value of 0.30 mm or less indicates sufficient low warpage. Products that could not be obtained due to defects during molding were judged as "×".

[0082] (5) Heat resistance Using the pellets obtained in each example and comparative example, the load deflection temperature at a stress of 1.80 MPa was measured flatwise in accordance with ISO 75-2. If the load deflection temperature is 175°C or higher, it can be judged that the heat resistance is good.

[0083] (6) Liquidity The pellets obtained in each example and comparative example were dried in a hot air dryer at 130°C for 3 hours. Then, using a Sumitomo Heavy Industries, Ltd. "SE50DUZ" injection molding machine, they were injected into strips 1 mm thick and 10 mm wide for 8 seconds, and the length (bar flow length) of the resulting strip-shaped molded product was measured. The injection conditions were a cylinder temperature of 260°C, a mold temperature of 80°C, and an injection pressure of 80 MPa. A fluidity value of 80 mm or more indicates sufficient fluidity.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Examples 1-14, Comparative Examples 1-9] According to the formulations shown in Tables 1 and 2, (A) thermoplastic polyester resin, (B) styrene resin, and (E) aliphatic alkyl acid phosphate were supplied from the main loading section of a twin-screw extruder, and (C) glass fibers and (D) non-fibrous inorganic filler were supplied from a secondary loading port located between the main loading port and the extruder tip. Melt mixing was performed in a twin-screw extruder (Toshiba Machine Co., Ltd., TEM37S (product name)) with a screw diameter of 37 mmφ, set to a cylinder temperature of 260°C. After cooling the strands extruded from the die in a cooling bath, they were pelletized using a strand cutter to obtain a thermoplastic polyester resin composition. The results of evaluating the obtained thermoplastic polyester resin composition using the above method are shown in Tables 1 and 2.

[0087] The following is clear from Tables 1 and 2.

[0088] A comparison of Examples 1-14 and Comparative Examples 1-9 shows that a thermoplastic polyester resin composition comprising 100 parts by mass of (A) thermoplastic polyester resin, consisting of 50-90 parts by mass of (A-1) polybutylene terephthalate resin and 10-50 parts by mass of (A-2) polyethylene terephthalate resin, blended with 5-25 parts by mass of (B) styrene resin, 10-50 parts by mass of (C) glass fiber, and 10-50 parts by mass of (D) non-fibrous inorganic filler, exhibits excellent mechanical properties, heat resistance, moldability, and low warpage. Furthermore, by using recycled polyethylene terephthalate resin as (A-2) polyethylene terephthalate resin, moldability can be improved, and the composition offers superior economic and environmental performance.

Claims

1. A thermoplastic polyester resin composition comprising 100 parts by mass of (A) thermoplastic polyester resin, which consists of (A-1) 50 to 90 parts by mass of polybutylene terephthalate resin and (A-2) 10 to 50 parts by mass of polyethylene terephthalate resin, blended with (B) 5 to 25 parts by mass of styrene resin, (C) 10 to 50 parts by mass of glass fiber, and (D) 10 to 50 parts by mass of non-fibrous inorganic filler.

2. The thermoplastic polyester resin composition according to claim 1, characterized in that the (B) styrene-based resin comprises at least one selected from acrylonitrile / styrene copolymer, acrylonitrile / styrene / glycidyl methacrylate copolymer, and acrylonitrile / butadiene / styrene copolymer.

3. The thermoplastic polyester resin composition according to claim 1 or 2, characterized in that the (D) non-fibrous inorganic filler is glass flakes.

4. The thermoplastic polyester resin composition according to claim 1 or 3, characterized in that the (B) styrene-based resin comprises at least one selected from acrylonitrile / styrene copolymer and acrylonitrile / styrene / glycidyl methacrylate copolymer.

5. The thermoplastic polyester resin composition according to claim 1 or 2, characterized in that the (A-2) polyethylene terephthalate resin is recycled polyethylene terephthalate resin.

6. The thermoplastic polyester resin composition according to claim 1 or 2, further comprising 100 parts by mass of (A) thermoplastic polyester resin and 0.01 to 5.0 parts by mass of (E) aliphatic alkyl acid phosphate.

7. The thermoplastic polyester resin composition according to claim 1 or claim 2, wherein the ratio of the major axis (longest straight distance of the cross-section) to the minor axis (longest straight distance perpendicular to the major axis) of the cross-section perpendicular to the longitudinal direction of the glass fiber is 1.3 to 10.

0.

8. A molded article comprising the thermoplastic polyester resin composition according to claim 1 or 2.

Images