Polyester resin composition and molded product decorated using hot stamping foil

Abstract

A polyester resin composition capable of obtaining a molded product having high rigidity and less appearance defects due to floating fibers of a fiber reinforcing material or the like, having a good mirror surface appearance, excellent surface smoothness, and capable of heat stamping decoration, the polyester resin composition containing 30 to 55 parts by mass of a polybutylene terephthalate resin (A), 8 to 38 parts by mass of a polyethylene terephthalate resin (B), 3 to 20 parts by mass of a copolymer polyester resin (C), 0 to 8 parts by mass of a polycarbonate-based resin (D), and 4 to 23 parts by mass of a carbon fiber-based reinforcing material (E), the copolymer polyester resin (C) being a copolymer polyethylene terephthalate resin (C1) and / or a copolymer polybutylene terephthalate resin (C2), wherein 0 to 2 parts by mass of an ester exchange inhibitor (F) is contained relative to 100 parts by mass of the total of the (A), (B), (C), (D), and (E), and the polyester resin composition has a flexural modulus of 5.8 GPa or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyester resin composition containing a thermoplastic polyester resin and carbon fibers and reinforced with carbon fibers. In detail, it relates to a polyester resin composition which can obtain a molded product having high rigidity, high strength, and less appearance defects such as fiber floating, and having a good mirror surface appearance and excellent surface smoothness, and is suitable for surface decoration secondary processing, particularly for hot stamping decoration. BACKGROUND

[0002] Generally, in the case of performing hot stamping (foil pressing) processing, in order to make the appearance after processing excellent, the surface smoothness of the molded product is required. Therefore, a resin composition of a styrene resin or the like having excellent surface secondary processing properties, which has excellent molding processability, has been proposed (Patent Documents 1, 2, 3). However, they do not contain a fiber reinforcing material, and therefore the rigidity is insufficient depending on the use of the molded product.

[0003] In Patent Document 4, a hot stamping substrate formed of a polylactic acid resin composition containing a glass fiber reinforcing material has been proposed, but the rigidity is also insufficient. Generally, in order to obtain sufficient rigidity, an inorganic reinforcing material such as glass fiber is added, but when the amount of addition is increased, the inorganic reinforcing material such as glass fiber is easily floated on the surface of the molded product, and sufficient surface smoothness is not obtained, and therefore it is not suitable for hot stamping decoration. In this case, in order to impart surface smoothness and foil adhesion, primer coating is required, and there are problems of an increase in the number of processing steps and an increase in cost.

[0004] Therefore, in recent years, in order to perform process simplification and cost reduction in a part requiring rigidity, a resin composition for a molded product having excellent surface smoothness and capable of performing hot stamping decoration has been demanded.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT DOCUMENTS

[0007] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 9-249780

[0008] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 10-60221

[0009] Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 11-60856

[0010] Patent Document 4: Japanese Patent Application Laid-Open (JP-A) No. 2015-120807 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] The present application provides a polyester resin composition having high rigidity and less appearance defects such as fiber floating of a fiber reinforcing material, good mirror surface appearance, excellent surface smoothness, and capable of heat stamping decoration.

[0013] Technical solution to the problem

[0014] To solve the above problem, the present inventors have intensively studied the composition and properties of a polyester resin composition, and as a result, have found that the above problem can be solved by containing a specific resin in an appropriate amount and appropriately adjusting the ratio of each component, thereby completing the present application.

[0015] That is, the present application has the following composition.

[0016] [1] A polyester resin composition, characterized by containing 30 to 55 parts by mass of a polybutylene terephthalate resin (A), 8 to 38 parts by mass of a polyethylene terephthalate resin (B), 3 to 20 parts by mass of a copolymer polyester resin (C), 0 to 8 parts by mass of a polycarbonate resin (D), and 4 to 23 parts by mass of a carbon fiber-based reinforcing material (E), wherein the total of the (A), (B), (C), (D), and (E) is 100 parts by mass, the copolymer polyester resin (C) is a copolymer polyethylene terephthalate resin (C1) and / or a copolymer polybutylene terephthalate resin (C2), and wherein 0 to 2 parts by mass of an ester exchange inhibitor (F) is contained relative to 100 parts by mass of the total of the (A), (B), (C), (D), and (E), and the polyester resin composition has a flexural modulus of 5.8 GPa or more.

[0017] [2] The polyester resin composition according to [1], wherein a molded product of 100 mm x 100 mm x 3 mm (thickness) obtained by injection molding the polyester resin composition at a cylinder temperature of 275°C and a mold temperature of 105°C has a surface roughness of 0.15 μm or less.

[0018] [3] The polyester resin composition according to [1] or [2], which is used for a molded product decorated with a hot stamping foil.

[0019] [4] A molded product decorated with a hot stamping foil, which contains the polyester resin composition according to [1] or [2].

[0020] Effects of the invention

[0021] According to the present application, in order to exhibit rigidity, the addition amount of the fiber reinforcing material can be suppressed by using carbon fibers having more excellent rigidity instead of glass fibers, and the fiber reinforcing material can be suppressed from floating on the surface by incorporating a resin having low crystallinity, and thus the surface smoothness of the molded product can be greatly improved, and the molded product can be suitable for hot stamping decoration. DETAILED DESCRIPTION

[0022] Hereinafter, the present application will be described in detail. The content of each component constituting the polyester resin composition described below is indicated by mass parts, which is the mass part when the total of the polybutylene terephthalate resin (A), the polyethylene terephthalate resin (B), the copolymer polyester resin (C), the polycarbonate-based resin (D), and the carbon fiber-based reinforcing material (E) is set to 100 mass parts. In the production of the polyester resin composition of the present application, the mass ratio of the amount of each component to be added is the content ratio in the polyester resin composition.

[0023] The polybutylene terephthalate resin (A) in the present application refers to a resin that is the main component of the total polyester resin in the resin composition of the present application. It is preferable that it is the resin having the highest content among the total polyester resin. There is no particular limitation on the polybutylene terephthalate resin (A), but it is preferable to use a homopolymer containing terephthalic acid and 1,4-butanediol. Furthermore, within a range that does not impair moldability, crystallinity, surface gloss, and the like, when the total acid component constituting the polybutylene terephthalate resin (A) is set to 100 mol%, and the total diol component is set to 100 mol%, other components can be copolymerized to about 5 mol%. That is, other components can be copolymerized to 5 mol% or less. As the other components, the components described below used in the copolymer polybutylene terephthalate resin can be mentioned.

[0024] As a measure of the molecular weight of the polybutylene terephthalate resin (A), the intrinsic viscosity (0.1 g of the resin is dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and measured at 30°C using an Ubbelohde viscometer) is preferably in the range of 0.5 to 0.9 dl / g, and more preferably in the range of 0.6 to 0.8 dl / g. In the case of less than 0.5 dl / g, there is a tendency that the toughness of the resin is greatly reduced, and in addition, burrs are easily generated due to excessively high flowability. On the other hand, when it is greater than 0.9 dl / g, it is difficult to obtain a sufficient appearance in the resin composition of the present application due to the influence of the reduction in flowability (the range of molding conditions becomes narrow).

[0025] The content of the polybutylene terephthalate resin (A) is 30 to 55 mass parts, preferably 40 to 52 mass parts, and more preferably 44 to 52 mass parts. By adding the polybutylene terephthalate resin (A) in this range, various properties can be satisfied.

[0026] The polyethylene terephthalate resin (B) in the present application is essentially a homopolymer of polyethylene terephthalate units. In addition, within a range that does not impair various properties, when the total acid component that constitutes the polyethylene terephthalate resin (B) is set to 100 mol%, and the total diol component is set to 100 mol%, other components can be copolymerized to about 5 mol%. That is, other components can be copolymerized to 5 mol% or less. As the other components, there can be mentioned the components described below that are used in the copolymerized polyethylene terephthalate resin. As the other components, there are also included diethylene glycol that is generated by polycondensation of ethylene glycol at the time of polymerization.

[0027] As a measure of the molecular weight of the polyethylene terephthalate resin (B), the intrinsic viscosity (0.1 g of the resin is dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and measured at 30°C using an Ubbelohde viscometer) is preferably 0.4 to 1.0 dl / g, and more preferably 0.5 to 0.9 dl / g. When less than 0.4 dl / g, there is a tendency for the strength of the resin to decrease, and when more than 1.0 dl / g, there is a tendency for the flowability of the resin to decrease.

[0028] The content of the polyethylene terephthalate resin (B) is 8 to 38 parts by mass, and preferably 10 to 35 parts by mass. By incorporating the polyethylene terephthalate resin (B) within this range, various properties can be satisfied.

[0029] The copolymerized polyester resin (C) in the present application is a copolymerized polyethylene terephthalate resin (Cl) and / or a copolymerized polybutylene terephthalate resin (C2).

[0030] The copolymerized polyethylene terephthalate resin (Cl) in the present application is a resin in which, when the total acid component that constitutes it is set to 100 mol%, and the total diol component that constitutes it is set to 100 mol%, ethylene glycol is 40 mol% or more, and the total of terephthalic acid and ethylene glycol is 80 to 180 mol%. The copolymerized polyethylene terephthalate resin (Cl) is preferably a resin in which ethylene glycol is 50 mol% or more, and the total of terephthalic acid and ethylene glycol is 150 to 175 mol%. As the copolymerization component, at least one selected from the group consisting of isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalene dicarboxylic acid, diethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, and 2-methyl-1,3-propanediol can be contained as the copolymerization component, and is preferably amorphous. Of these, from the viewpoint of various properties as the copolymerization component, neopentyl glycol, or the combination of neopentyl glycol and isophthalic acid is preferable. As the copolymerization component, 1,4-butanediol is preferably 20 mol% or less.

[0031] When the total diol component of the copolymerized polyethylene terephthalate resin (C1) is taken as 100 mol%, the copolymerization ratio of neopentyl glycol is preferably 20 to 60 mol%, more preferably 25 to 50 mol%.

[0032] When the total acid component of the copolymerized polyethylene terephthalate resin (C1) is taken as 100 mol%, the copolymerization ratio of isophthalic acid is preferably 20 to 60 mol%, more preferably 25 to 50 mol%.

[0033] As a measure of the molecular weight of the copolymerized polyethylene terephthalate resin (C1), the intrinsic viscosity (0.1 g of the resin is dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and measured at 30°C using an Ubbelohde viscometer) is preferably 0.4 to 1.5 dl / g, more preferably 0.4 to 1.3 dl / g. When less than 0.4 dl / g, there is a tendency for the toughness to decrease, and when more than 1.5 dl / g, there is a tendency for the flowability to decrease.

[0034] The copolymerized polybutylene terephthalate resin (C2) in the present application is a resin in which, when the total acid component is taken as 100 mol% and the total diol component is taken as 100 mol%, 1,4-butanediol is 80 mol% or more and the total of terephthalic acid and 1,4-butanediol is 120 to 180 mol%. The copolymerized polybutylene terephthalate resin (C2) is preferably a resin in which 1,4-butanediol is 80 mol% or more and the total of terephthalic acid and 1,4-butanediol is 140 to 180 mol%. As the copolymerization component, at least one selected from the group consisting of isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalene dicarboxylic acid, ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,2-propanediol, 1,3-propanediol and 2-methyl-1,3-propanediol can be contained as the copolymerization component. Of these, isophthalic acid is preferred as the copolymerization component, and when the total acid component of the copolymerized polybutylene terephthalate resin (C2) is taken as 100 mol%, the copolymerization ratio is preferably 20 to 80 mol%, more preferably 20 to 60 mol%, further preferably 20 to 40 mol%. When the copolymerization ratio is less than 20 mol%, the transferability to a mold is poor, and there is a tendency for a sufficient appearance to be difficult to obtain, and when the copolymerization amount is more than 80 mol%, a decrease in the molding cycle and a decrease in the releasability can sometimes occur.

[0035] As a measure of the molecular weight of the copolymerized polybutylene terephthalate resin (C2), the intrinsic viscosity (0.1 g of the resin is dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and measured at 30°C using an Ubbelohde viscometer) is preferably 0.4 to 1.5 dl / g, more preferably 0.4 to 1.3 dl / g. When less than 0.4 dl / g, there is a tendency for the toughness to decrease, and when more than 1.5 dl / g, there is a tendency for the flowability to decrease.

[0036] The content of the copolymerized polyester resin (C) is 3 to 20 parts by mass, preferably 7 to 18 parts by mass, more preferably 9 to 17 parts by mass. When less than 3 parts by mass, the fiber reinforcement floating and the appearance defect due to the mold transfer become apparent, and when more than 20 parts by mass, although the appearance of the molded article becomes good, the molding cycle becomes long, and thus is not preferable.

[0037] As the copolymerized polyester resin (C), the copolymerized polyethylene terephthalate resin (C1) or the copolymerized polybutylene terephthalate resin (C2) can be used alone, or the copolymerized polyethylene terephthalate resin (C1) and the copolymerized polybutylene terephthalate resin (C2) can be used in combination, but the use in combination is more preferable. In the case where the copolymerized polyethylene terephthalate resin (C1) and the copolymerized polybutylene terephthalate resin (C2) are used in combination, the mass ratio (C1:C2) is preferably 80:20 to 30:70, more preferably 70:30 to 40:60, and further preferably 60:40 to 50:50. By using the copolymerized polyethylene terephthalate resin (C1) and the copolymerized polybutylene terephthalate resin (C2) in the above-described mass ratio, the molded article obtained from the polyester resin composition of the present application can be a molded article having a good mirror surface appearance.

[0038] The polycarbonate in the polycarbonate-based resin (D) used in the present application is produced by a solvent method, i.e., a reaction of a dihydric phenol with a carbonate precursor such as phosgene or an ester exchange reaction of a dihydric phenol with diphenyl carbonate in the presence of a known acid acceptor, a molecular weight adjusting agent, in a solvent such as dichloromethane. Here, the dihydric phenol used is preferably a bisphenol, particularly 2,2-bis(4-hydroxyphenyl)propane, i.e., bisphenol A. In addition, it can be a substance in which a part or all of bisphenol A is replaced with another dihydric phenol. As the dihydric phenol other than bisphenol A, for example, there are compounds such as hydroquinone, 4,4-dihydroxydiphenyl, bis(4-hydroxyphenyl)alkane, and halogenated bisphenols such as bis(3,5-dibromo-4-hydroxyphenyl)propane and bis(3,5-dichloro-4-hydroxyphenyl)propane. The polycarbonate can be a homopolymer using one dihydric phenol or a copolymer using two or more. The polycarbonate-based resin (D) preferably uses a resin containing only polycarbonate. As the polycarbonate-based resin (D), a resin copolymerized with a component other than polycarbonate (e.g., a polyester component) within a range not impairing the effects of the present application (20 mass% or less) can also be used.

[0039] The polycarbonate-based resin (D) used in the present application is particularly preferably a resin having high flowability, and a resin having a melt volume flow rate (unit: cm 3 / 10 min) of 20 to 100 at 300°C under a load of 1.2 kg is preferably used, more preferably a resin having a melt volume flow rate of 25 to 95, and further preferably a resin having a melt volume flow rate of 30 to 90. When a resin having a melt volume flow rate of less than 20 is used, the flowability is significantly reduced, and sometimes the strand stability is reduced and the moldability is deteriorated. When the melt volume flow rate is greater than 100, the molecular weight is too low, and problems such as a reduction in physical properties or generation of gas due to decomposition are easily caused.

[0040] The content of the polycarbonate-based resin (D) used in the present application is 0 to 8 parts by mass. By adding the specified amount of the copolymerized polyester resin (C), a polyester resin composition having the effects of the present application can be obtained, and therefore the polycarbonate-based resin (D) is not an essential component. However, by adding the polycarbonate-based resin (D), the molded article obtained from the polyester resin composition of the present application can become a molded article having a more excellent mirror surface appearance. In the case where the polycarbonate-based resin (D) is added, the preferable addition amount is 2 to 6 parts by mass. When the addition amount is greater than 8 parts by mass, problems such as a deterioration in molding cycle due to a reduction in crystallinity, a reduction in flowability leading to a poor appearance, and the like are easily caused, and therefore it is not preferable.

[0041] In the present application, it is more preferable to use a copolymerized polyethylene terephthalate resin (C1) and a copolymerized polybutylene terephthalate resin (C2) in combination as the copolymerized polyester resin (C), and further to incorporate a polycarbonate-based resin (D). By incorporating the copolymerized polyethylene terephthalate resin (C1), the copolymerized polybutylene terephthalate resin (C2) and the polycarbonate-based resin (D) in a predetermined ratio, the floating of the fiber reinforcing material, particularly carbon fibers, can be highly suppressed, and a molded product having a more excellent mirror surface appearance can be obtained.

[0042] The carbon fiber-based reinforcing material (E) in the present application is not particularly limited as long as it contains carbon fibers having a chopped length of about 3 to 8 mm. As for the manufacturing method, it is not limited as long as it is a generally known method. In order to improve the wettability of the resin and improve the handling, carbon fibers having a coupling agent and a convergence agent attached to the surface of the carbon fibers can also be used. The coupling agent can be of various types such as an amine type, an epoxy type, a mercapto type, etc., but the epoxy type is preferable. As for the convergence agent, an epoxy type or a urethane type is preferable. As for the attachment amount, 0.1 to 5 parts by mass per 100 parts by mass of the carbon fibers is preferable, but there is no particular limitation.

[0043] The chopped length of the carbon fibers can be measured by electron microscope observation.

[0044] In the polyester resin composition of the present application, in order to achieve the object, an inorganic reinforcing material other than carbon fibers can also be used in combination as the carbon fiber-based reinforcing material (E) without impairing the characteristics. Specifically, generally commercially available mica, wollastonite, acicular wollastonite, glass flakes, glass beads, etc. can be used without problems, and these are generally treated with a known coupling agent to obtain the material. In the case where an inorganic reinforcing material other than carbon fibers is used in combination, the total amount of the carbon fibers and the inorganic reinforcing material other than carbon fibers is taken as the content of the carbon fiber-based reinforcing material (E) when considering the content of each component of the polyester resin composition of the present application. In the case where the carbon fibers and the inorganic reinforcing material other than carbon fibers are used in combination, the carbon fibers are preferably used in an amount of 50% by mass or more in the carbon fiber-based reinforcing material (E). It is also preferable to use only the carbon fibers as the carbon fiber-based reinforcing material (E) without using other inorganic reinforcing materials.

[0045] The content of the carbon fiber-based reinforcing material (E) in the present application is preferably 4 to 23 parts by mass, more preferably 5 to 22 parts by mass, and even more preferably 7 to 13 parts by mass from the viewpoints of rigidity, strength and appearance.

[0046] As its name, the ester exchange inhibitor (F) used in the present application means a stabilizer that prevents the ester exchange reaction of polyester-based resins. In the mixing of polyester-based resins with each other or the like, regardless of the conditions at the time of production, a considerable ester exchange occurs by the application of heat history. When the degree thereof becomes very large, the desired properties cannot be obtained by the mixing. In particular, the ester exchange of polybutylene terephthalate with polycarbonate often occurs, and thus in this case, the crystallinity of the polybutylene terephthalate is greatly reduced, and thus is not preferable. In the present application, by adding the ester exchange inhibitor (F), in particular, the ester exchange reaction of the polybutylene terephthalate resin (A) with the polycarbonate-based resin (D) is prevented, and thus the appropriate crystallinity can be maintained.

[0047] As the ester exchange inhibitor (F), a phosphorus-based compound having a catalyst deactivation effect for polyester-based resins can be preferably used, and for example, "ADK STAB AX-71" manufactured by ADEKA Corporation can be used.

[0048] The addition amount of the ester exchange inhibitor (F) used in the present application is 0 to 2 parts by mass, and the ester exchange inhibitor (F) does not necessarily need to be added in the case where the polycarbonate-based resin (D) is not added, and in the case where the polycarbonate-based resin (D) is added, the addition amount of the ester exchange inhibitor (F) is preferably 0.05 to 2 parts by mass, more preferably 0.1 to 1 part by mass, and further preferably 0.1 to 0.5 parts by mass. In the case of less than 0.05 parts by mass, the cases where the required ester exchange prevention performance cannot be exerted are more, and on the contrary, even if more than 2 parts by mass is added, the improvement of the effect is hardly confirmed, and sometimes becomes a main cause of the increase of gas or the like.

[0049] In addition, in the polyester resin composition of the present application, as necessary, various additives known per se can be contained within a range not impairing the characteristics as the present application. As the additives known per se, for example, colorants such as pigments, release agents, heat-resistant stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, modifiers, antistatic agents, flame retardants, dyes, and the like can be exemplified. These various additives can be contained in total up to 5% by mass, when the polyester resin composition is taken as 100% by mass. That is, the total of the (A), (B), (C), (D), (E), and (F) is preferably 95 to 100% by mass, in 100% by mass of the polyester resin composition.

[0050] As the release agent, long-chain fatty acids or esters and metal salts thereof, amide-based compounds, polyethylene wax, silicon, polyethylene oxide, etc. can be mentioned. As the long-chain fatty acid, those having a carbon number of 12 or more are particularly preferred, and examples include stearic acid, 12-hydroxystearic acid, behenic acid, montanic acid, etc., and part or all of the carboxylic acid can be esterified with monoethylene glycol or polyethylene glycol, or a metal salt can be formed. As the amide-based compound, ethylene bis-p-phenyl dicarboxamide, methylene bis-stearamide, etc. can be mentioned. These release agents can be used alone or as a mixture.

[0051] As the method for producing the polyester resin composition of the present application, it can be produced by mixing the above-mentioned components and various additives as necessary and melt-kneading. The melt-kneading method can use any method known to those skilled in the art, and a single-screw extruder, a twin-screw extruder, a pressurized kneader, a Banbury mixer, etc. can be used. Among them, a twin-screw extruder is preferably used. As the general melt-kneading conditions, the barrel temperature in the twin-screw extruder is 240 to 290°C, and the kneading time is 2 to 15 minutes.

[0052] The polyester resin composition of the present application has the above-mentioned constitution, and thereby the flexural modulus measured according to ISO-178 is 5.8 GPa or more. The flexural modulus is preferably 7 GPa or more, and more preferably 8 GPa or more. The upper limit of the flexural modulus is not particularly limited, but in the polyester resin composition of the present application, it is around 20 GPa. The flexural modulus is measured as described in the Examples described later.

[0053] The surface roughness of the molded product of 100 mm x 100 mm x 3 mm (thickness) obtained by injection molding the polyester resin composition at a barrel temperature of 275°C and a mold temperature of 105°C is preferably 0.15 μm or less. This surface roughness can be achieved by having the above-mentioned constitution. The surface roughness can be obtained by the measurement method described in the Examples described later.

[0054] The hot stamping in the present application is not particularly limited as long as the polyester resin composition of the present application is used. For example, it is produced by making the polyester resin composition of the present application into a molded product by a publicly known molding method such as injection molding, laminating a hot stamping foil (transfer foil) on the molded product, and performing heat pressing to transfer it. In this way, a molded product after decoration by the hot stamping foil can be obtained.

[0055] As the form of the hot stamping foil, a metal foil layer and an adhesive layer are essential components, but preferably, the following 5 layers are included: 1) a base film layer, 2) a release layer, 3) a protective layer, 4) a metal foil layer, and 5) an adhesive layer. The constituent components of each layer are not particularly limited, and the heat transfer method is not particularly limited.

[0056] Examples

[0057] Hereinafter, the present application will be described more specifically by examples, but the present application is not limited to these examples. Note that the measured values described in the examples are values measured by the following methods.

[0058] (1) Inherent viscosity of polyester resin

[0059] 0.1 g of the resin was dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane (mass ratio 6 / 4), and the measurement was performed at 30°C using an Ubbelohde viscometer. (Unit: dl / g)

[0060] (2) Mirror surface appearance of molded product

[0061] A molded product of 100 mm x 100 mm x 3 mm was obtained by injection molding at a cylinder temperature of 275°C and a mold temperature of 105°C. At the time of molding, the injection speed was performed in the range of 1 second of filling time. The appearance of the obtained molded product was observed visually, and judged according to the following standards. If it was "O", it was a level without particular problems.

[0062] O: Some appearance defects occurred in a part (particularly, in the end part of the molded product or the like), or the image reflected on the molded product looked slightly distorted.

[0063] O: Some appearance defects occurred in a part (particularly, in the end part of the molded product or the like), or the image reflected on the molded product looked slightly distorted.

[0064] X: Appearance defects occurred in the entire molded product, or the image reflected on the molded product was not clear.

[0065] (3) Surface roughness

[0066] A molded product of 100 mm x 100 mm x 3 mm (thickness) was obtained by injection molding at a cylinder temperature of 275°C and a mold temperature of 105°C. At the time of molding, the injection speed was performed in the range of 1 second of filling time. The center part of the surface of 100 mm x 100 mm in the obtained molded product was observed at 10 times magnification using a white light interference microscope (trade name: "VertScan VS1530, Hitachi High-Tech Manufacturing Corp."), and the surface roughness (arithmetic mean height (Sa)) was measured. If the surface roughness was 0.15 μm or less, it was "O" which was a pass, and in the case of more than 0.15 μm, it was "X" which was a fail.

[0067] (4) Flexural modulus

[0068] Determined in accordance with ISO-178. Test pieces were injection molded at a cylinder temperature of 275°C, a mold temperature of 100°C, a filling time of 1 second or less, and a cooling time of 12 seconds.

[0069] The compounding ingredients used in the examples and comparative examples are shown below.

[0070] Polybutylene terephthalate resin (A): manufactured by Toyobo Co., Ltd., intrinsic viscosity 0.75 dl / g

[0071] Polyethylene terephthalate resin (B): manufactured by Toyobo Co., Ltd., intrinsic viscosity 0.63 dl / g

[0072] Copolymerized polyethylene terephthalate resin (C1): a copolymer having a composition ratio of TPA / EG / NPG = 100 / 70 / 30 (mole %), manufactured by Toyobo Co., Ltd., a trial product of Toyobo VYLON (registered trademark), intrinsic viscosity 0.83 dl / g

[0073] Copolymerized polybutylene terephthalate resin (C2): a copolymer having a composition ratio of TPA / IPA / 1,4-BD = 70 / 30 / 100 (mole %), manufactured by Toyobo Co., Ltd., a trial product of Toyobo VYLON (registered trademark), intrinsic viscosity 0.73 dl / g

[0074] (Abbreviations respectively represent TPA: terephthalic acid, IPA: isophthalic acid, 1,4-BD: 1,4-butanediol, EG: ethylene glycol, NPG: neopentyl glycol component)

[0075] Polycarbonate-based resin (D): "SD POLYCA 200-80" manufactured by Showa Denko Polycarbonate Co., Ltd., melt volume flow rate (300°C, load 1.2 kg) 80 cm 3 / 10 min

[0076] Carbon fiber-based reinforcing material (E): "CF UW" manufactured by Japan Polymer Industries, Ltd., chopped strands of a carbon fiber bundle having a chopped length of 6 mm

[0077] Ester exchange inhibitor (F): "ADK STAB AX-71" manufactured by ADEKA Co., Ltd.

[0078] Glass fiber-based reinforcing material: "T-120H" manufactured by Nippon Electric Glass Co., Ltd.

[0079] Examples 1 to 8, Comparative Examples 1 to 6

[0080] The polyester resin compositions of the examples and comparative examples were weighed out in the proportions (parts by mass) shown in Tables 1 and 2 from the above-described raw materials, and were kneaded in a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 270°C and a screw rotation speed of 200 rpm. The raw materials other than the reinforcing material were fed into the twin-screw extruder from a hopper, and the reinforcing material was fed from a vent port in a side feeding manner. The pellets of the obtained polyester resin compositions were dried, and various evaluation samples were molded using an injection molding machine. The evaluation results are shown in Tables 1 and 2. The polyester resin compositions of the examples and comparative examples were weighed out in the proportions (parts by mass) shown in Tables 1 and 2 from the above-described raw materials, and were kneaded in a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 270°C and a screw rotation speed of 200 rpm. The raw materials other than the reinforcing material were fed into the twin-screw extruder from a hopper, and the reinforcing material was fed from a vent port in a side feeding manner. The pellets of the obtained polyester resin compositions were dried, and various evaluation samples were molded using an injection molding machine. The evaluation results are shown in Tables 1 and 2.

[0081] [Table 1]

[0082]

[0083] [Table 2]

[0084]

[0085] As is apparent from Tables 1 and 2, since the examples 1 to 8 were compounded in the prescribed proportions, the flexural modulus was maintained at 5.8 GPa or more, and the mirror surface appearance and surface smoothness (surface roughness of 0.15 μm or less) were excellent.

[0086] On the other hand, the comparative examples 1 and 2, since the copolymerized polyester resin (C) and the polycarbonate-based resin (D) were not compounded, and a glass fiber reinforcing material was compounded instead of the carbon fiber-based reinforcing material (E), the rigidity (flexural modulus) was inferior to the examples, or the mirror surface appearance and surface smoothness were inferior. The comparative examples 3 and 4, since a glass fiber reinforcing material was compounded instead of the carbon fiber-based reinforcing material (E), the rigidity (flexural modulus) was inferior to the examples, or the mirror surface appearance and surface smoothness were inferior. The comparative example 5, since the amount of the carbon fiber-based reinforcing material (E) was more than the prescribed amount, the rigidity was excellent, but the mirror surface appearance and surface smoothness were inferior. The comparative example 6, since the polycarbonate-based resin (D) was compounded, but the copolymerized polyester resin (C) was not compounded, the mirror surface appearance was inferior to the examples.

[0087] Industrial applicability

[0088] According to the present application, a molded product having high rigidity and having few appearance defects due to floating fibers or the like of the fiber reinforcing material, having a good mirror surface appearance, and excellent surface smoothness can be obtained. Therefore, it is greatly contributive to the industry to be suitably used for interior parts and decorative parts for automobiles obtained by injection molding, various signs and appearance design covers, and parts for household electric appliance housings, which require secondary surface processing such as hot stamping, and which require parts having a certain degree of rigidity.

Claims

1. A polyester resin composition, characterized by comprising: A polyester resin composition containing 30 to 55 parts by mass of a polybutylene terephthalate resin (A), 8 to 38 parts by mass of a polyethylene terephthalate resin (B), 3 to 20 parts by mass of a copolyester resin (C), 0 to 8 parts by mass of a polycarbonate resin (D), and 4 to 23 parts by mass of a carbon fiber reinforcing material (E), the total of the (A), (B), (C), (D), and (E) being 100 parts by mass, the copolyester resin (C) being a copolyethylene terephthalate resin (C1) and / or a copolybutylene terephthalate resin (C2), wherein 0 to 2 parts by mass of an ester exchange inhibitor (F) is contained relative to 100 parts by mass of the total of the (A), (B), (C), (D), and (E), the flexural modulus of the polyester resin composition being 5.8 GPa or greater, The copolyethylene terephthalate resin (C1) is a resin in which, when the total of all acid components is taken as 100 mol% and the total of all diol components is taken as 100 mol%, ethylene glycol is 40 mol% or greater and the total of terephthalic acid and ethylene glycol is 80 to 180 mol%, the copolymer component of the copolyethylene terephthalate resin (C1) being at least one selected from isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalene dicarboxylic acid, diethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, and 2-methyl-1,3-propanediol, The copolybutylene terephthalate resin (C2) is a resin in which, when the total of all acid components is taken as 100 mol% and the total of all diol components is taken as 100 mol%, 1,4-butanediol is 80 mol% or greater and the total of terephthalic acid and 1,4-butanediol is 120 to 180 mol%, the copolymer component of the copolybutylene terephthalate resin (C2) being at least one selected from isophthalic acid, sebacic acid, adipic acid, trimellitic acid, 2,6-naphthalene dicarboxylic acid, ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,2-propanediol, 1,3-propanediol, and 2-methyl-1,3-propanediol.

2. The polyester resin composition according to claim 1, wherein the surface roughness of a molded product of 100 mm x 100 mm x 3 mm thick obtained by injection molding the polyester resin composition at a cylinder temperature of 275°C and a mold temperature of 105°C is 0.15 μm or less.

3. The polyester resin composition according to claim 1 or 2, which is used for a molded product decorated with a hot stamping foil.

4. A molded product decorated with a hot stamping foil, which contains the polyester resin composition according to claim 1 or 2.

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