JP7507153B2 - Resin composition and method for producing same - Google Patents

Description

The present invention relates to a resin composition and a method for producing the same.

Polybutylene terephthalate resin (PBT resin) has excellent properties such as mechanical properties, electrical properties, heat resistance, chemical resistance, and solvent resistance, and is therefore widely used as an engineering plastic for various applications such as automotive parts, electrical and electronic parts, etc.
PBT resin has a relatively high crystallization rate. Therefore, in order to slow down the solidification rate of the resin in the mold during molding to improve the transferability of the mold surface and thereby improve the appearance of the molded product, PBT resin may be alloyed with a low-crystalline polyester resin such as polyethylene terephthalate resin (PET resin). For example, Patent Document 1 proposes a polybutylene terephthalate resin composition containing a specific PET resin as an alloy resin.

JP 2018-203932 A

In a polyester resin composition containing a PBT resin and a PET resin, an ester exchange reaction easily occurs between the PBT resin and the PET resin when melted. If the ester exchange reaction proceeds too much, the melting point and crystallization temperature of the resin composition may change significantly. In such a case, problems such as a decrease in thermal stability, a decrease in physical properties of a molded product, and a deterioration in moldability such as releasability from a mold, may occur.

An object of the present invention is to provide a resin composition suitable for producing molded articles having excellent appearance and thermal stability, and a method for producing the same.

The present inventors have found that when the crystallization temperature of a resin composition satisfies specific conditions, a molded article can have both good appearance and thermal stability, and have completed the present invention.
That is, the present invention relates to the following.
[1] A resin composition comprising a total of 100 parts by mass of a polybutylene terephthalate resin and a polyethylene terephthalate resin, and 0.1 to 1.0 part by mass of a phosphorus compound, and satisfying the following formulas I and II.
Formula I: Crystallization temperature Tc1 (°C) ≦ 195°C
Formula II: [Crystallization temperature Tc1 (°C)] - [Crystallization temperature Tc3 (°C)] ≦ 15°C
(In the formula, Tc1 represents the peak temperature (° C.) of the maximum endothermic peak in the DSC curve in differential scanning calorimetry (DSC) during the first temperature drop cycle when three cycles of heating from 40° C. to 280° C. at a heating rate of 10° C./min and cooling from 280° C. to 40° C. at a heating rate of 10° C./min are performed according to JIS K7121, and Tc3 represents the peak temperature (° C.) of the maximum endothermic peak in the DSC curve in differential scanning calorimetry (DSC) during the third temperature drop cycle.)
[2] The resin composition according to [1], wherein the content of the polyethylene terephthalate resin is 50 to 80 parts by mass per 100 parts by mass of the polybutylene terephthalate resin.
[3] The resin composition according to [1] or [2], which is used for producing an interior part for an automobile and/or an exterior part for an automobile.
[4] The resin composition according to any one of [1] to [3], wherein the phosphorus compound contains an organic phosphorus compound, and the content of the organic phosphorus compound is 0.1 to 0.2 parts by mass per 100 parts by mass of the polybutylene terephthalate resin and the polyethylene terephthalate resin combined.
[5] The resin composition according to any one of [1] to [4], further comprising an ester exchange promoter, and the content of the ester exchange promoter is 0.01 to 2 parts by mass per 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin.
[6] The resin composition according to any one of [1] to [5], which does not contain a halogen-based flame retardant or contains 5 mass% or less of a halogen-based flame retardant in the entire resin composition.
[7] A method for producing a resin composition according to any one of [1] to [6], comprising heat treating a polybutylene terephthalate resin and a polyethylene terephthalate resin under conditions that satisfy the following formula III to obtain a resin mixture, and mixing the resin mixture with a phosphorus compound to obtain a resin composition.
Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s)
[8] The method according to [7], in which a polybutylene terephthalate resin and a polyethylene terephthalate resin are heat-treated by melting and retaining them in a heating container, and then a phosphorus compound is added to the heating container and mixed by heating to obtain a resin composition.
[9] The method according to [7], comprising melt-extruding a polybutylene terephthalate resin and a polyethylene terephthalate resin to obtain a heat-treated resin mixture, and then heating and mixing the resin mixture with a phosphorus compound to obtain a resin composition.
[10] A method for producing the resin composition according to any one of [1] to [6], comprising mixing a polybutylene terephthalate resin and a polyethylene terephthalate resin to obtain a resin mixture, and heat-treating the resin mixture under conditions that satisfy the following formula III:
Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s)
and mixing the heat-treated resin mixture with a phosphorus compound.
[11] A molded product using the resin composition according to any one of [1] to [6].
[12] The molded article according to [11], which is an automobile interior part or an automobile exterior part.

According to the present invention, it is possible to provide a resin composition suitable for producing a molded article having excellent appearance and thermal stability, and a method for producing the same.

FIG. 2 is a schematic diagram showing the shape of an injection-molded product (an outer door handle escutcheon for an automobile) used in the evaluation of appearance.

An embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiment, and can be carried out by making appropriate modifications within the scope that does not impair the effects of the present invention.

[Resin composition]
The resin composition according to the present embodiment contains a polybutylene terephthalate resin, a polyethylene terephthalate resin, and a phosphorus compound.

(Polybutylene terephthalate resin)
Polybutylene terephthalate resin (PBT resin) is a polybutylene terephthalate resin obtained by polycondensation of a dicarboxylic acid component containing at least terephthalic acid or its ester-forming derivative (C _1-6 alkyl ester, acid halide, etc.) and a glycol component containing at least an alkylene glycol having 4 carbon atoms (1,4-butanediol) or its ester-forming derivative (acetylated product, etc.). In this embodiment, the polybutylene terephthalate resin is not limited to a homopolybutylene terephthalate resin (i.e., butylene terephthalate unit is 100 mol%), but may be a copolymer containing butylene terephthalate unit of 60 mol% or more, and may be a copolymer containing butylene terephthalate unit of 75 mol% or more and 95 mol% or less. When the polybutylene terephthalate unit is less than 60 mol%, the crystallization rate is slow and the releasability is reduced.

The amount of terminal carboxyl groups in the polybutylene terephthalate resin is not particularly limited as long as it does not impede the object of the present invention, but is preferably 30 meq/kg or less, more preferably 25 meq/kg or less.

The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited as long as it does not impede the object of the present invention, but is preferably 0.60 dL/g or more and 1.2 dL/g or less, more preferably 0.65 dL/g or more and 0.9 dL/g or less. When a polybutylene terephthalate resin having an intrinsic viscosity in such a range is used, the obtained polybutylene terephthalate resin composition has particularly excellent moldability. In addition, the intrinsic viscosity can be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL/g and a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL/g can be blended to prepare a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL/g. The intrinsic viscosity (IV) of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

In the preparation of polybutylene terephthalate resin, when an aromatic dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof is used as a comonomer component, for example, _C8-14 aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, _C4-16 alkane dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, _C5-10 cycloalkane dicarboxylic acids such as cyclohexane dicarboxylic acid, and ester-forming derivatives of these dicarboxylic acid components ( _C1-6 alkyl ester derivatives, acid halides, etc.) can be used. These dicarboxylic acid components can be used alone or in combination of two or more.

Among these dicarboxylic acid components, _C8-12 aromatic dicarboxylic acids such as isophthalic acid, and _C6-12 alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid are more preferred.

In the preparation of polybutylene terephthalate resin, when a glycol component other than 1,4-butanediol is used as a comonomer component, for example, _C2-10 alkylene glycols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, 1,3-octanediol, etc.; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, etc.; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; _C2-4 alkylene oxide adducts of bisphenol A such as 2-mol ethylene oxide adduct of bisphenol A and 3-mol propylene oxide adduct of bisphenol A; or ester-forming derivatives of these glycols (acetylated products, etc.) can be used. These glycol components can be used alone or in combination of two or more.

Among these glycol components, _C2-6 alkylene glycols such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol are more preferred.

Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4-carboxy-4'-hydroxybiphenyl, etc.; aliphatic hydroxycarboxylic acids such as glycolic acid, hydroxycaproic acid, etc.; C _3-12 lactones such as propiolactone, butyrolactone, _{valerolactone} , caprolactone (e.g., ε-caprolactone), etc.; and ester-forming derivatives of these comonomer components (C _1-6 alkyl ester derivatives, acid halides, acetylated products, etc.).

The crystallization temperature Tc1 _PBT of the polybutylene terephthalate resin is preferably 100°C to 200°C, more preferably 140°C to 198°C, even more preferably 160°C to 195°C, and particularly preferably 180°C to 195°C, in order to further improve the appearance of the resin composition. The crystallization temperature Tc1 _PBT is the peak crystallization temperature of the first cycle when the operation of increasing the temperature from 40°C to 260°C at a temperature increase rate of 10°C/min and then decreasing the temperature to 40°C at a temperature decrease rate of -10°C/min is repeated three times, as measured by DSC (differential scanning calorimetry) based on JIS K7121. The crystallization temperature of the polybutylene terephthalate resin may increase by melt kneading. For example, when a homopolybutylene terephthalate resin with an IV of 0.70 dL/g has a crystallization temperature of 176° C. immediately after polymerization, it may rise to 198° C. depending on the extrusion conditions when melt-kneaded. Therefore, the above temperature is the value after melt-kneading, and when a Japan Steel Works TEX30 twin-screw extruder is used, it refers to the crystallization temperature of the polybutylene terephthalate resin after melt-kneading under conditions of 260° C., 15 kg/hr, and 130 rpm.

The content of the polybutylene terephthalate resin is preferably 5 to 80 mass %, more preferably 10 to 70 mass %, and further preferably 15 to 60 mass %, of the total mass of the resin composition.

(Polyethylene terephthalate resin)
As the polyethylene terephthalate resin (PET resin), a polyethylene terephthalate resin obtained by polycondensing terephthalic acid or an ester-forming derivative thereof (C _1-6 alkyl ester, acid halide, or the like) as a dicarboxylic acid component and ethylene glycol or an ester-forming derivative thereof (acetylated product, or the like) as a diol component according to a known method can be used.

The polyethylene terephthalate resin may have, as a modifying component, a repeating unit derived from an aromatic dicarboxylic acid or an ester-forming derivative thereof (such as a _C1-6 alkyl ester or an acid halide) other than terephthalic acid or an ester-forming derivative thereof, in an amount of, for example, more than 0 mol % and 15 mol % or less relative to all repeating units derived from the dicarboxylic acid component.
The polyethylene terephthalate resin may also have, as a modifying component, a repeating unit derived from a diol other than ethylene glycol or an ester-forming derivative thereof (such as an acetylated product) in an amount of, for example, more than 0 mol % and 1 mol % or less relative to all repeating units derived from the diol component.

Examples of aromatic dicarboxylic acids other than terephthalic acid or their ester-forming derivatives include _C8-14 aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-dicarboxydiphenyl ether, or ester-forming derivatives of these dicarboxylic acid components ( _C1-6 alkyl ester derivatives, acid halides, etc.). These dicarboxylic acid components can be used alone or in combination of two or more.

Examples of glycols other than ethylene glycol or ester-forming derivatives thereof include _C2-10 alkylene glycols such as propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, and 1,3-octanediol; polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, and dipropylene glycol; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl; _C2-4 alkylene oxide adducts of bisphenol A, such as 2-mol ethylene oxide adduct of bisphenol A and 3-mol propylene oxide adduct of bisphenol A; and ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components may be used alone or in combination of two or more.

The crystallization temperature Tc1 _PET of the polyethylene terephthalate resin is preferably 210° C. or less, more preferably 205° C. or less, and even more preferably 200° C. or less, in order to further improve the appearance of the resin composition. The crystallization temperature Tc1 _PET is the peak crystallization temperature in the first cycle measured by DSC (differential scanning calorimetry) according to JIS K7121, in which the temperature is increased from 40° C. to 280° C. at a heating rate of 10° C./min, and then decreased to 40° C. at a cooling rate of −10° C./min, three times.

The content of the polyethylene terephthalate resin is preferably 50 to 80 parts by mass, more preferably 55 to 75 parts by mass, and even more preferably 60 to 70 parts by mass, per 100 parts by mass of the polybutylene terephthalate resin. By setting the content of the polyethylene terephthalate resin within the above range, it is possible to improve moldability, and also to improve the transferability of the mold surface during molding, thereby improving the appearance of the molded product.

In one embodiment, the resin composition preferably contains polybutylene terephthalate resin and polyethylene terephthalate resin as main components. The term "main components" means that the resin composition contains polybutylene terephthalate resin and polyethylene terephthalate resin in a total amount of 50% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more.

The resin composition may contain, in addition to the PBT resin and the PET resin, other amorphous resins such as polycarbonate resin (PC resin), polytrimethylene terephthalate resin (PTT resin), polycyclohexylene dimethylene terephthalate resin (PCT resin), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-styrene-butadiene copolymer (ABS resin), polystyrene resin (PS resin), etc. These amorphous resins may be used alone or in combination of two or more.

However, when the amorphous resin is a polyester-based resin, there is a possibility that moldability and mechanical properties may be affected due to ester exchange with PBT resin or PET resin. Therefore, when a polyester-based amorphous resin is contained, its amount is preferably 10 mass % or less, and more preferably 5 mass % or less, of the entire resin composition.

(Phosphorus compounds)
Examples of the phosphorus compound include organic phosphorus compounds (e.g., organic phosphates, organic phosphites, organic phosphonates, and/or organic phosphonites, etc.) and inorganic phosphorus compounds (alkali metal phosphates, and/or alkaline earth metal phosphates, etc.), and at least one selected from these can be used. The phosphorus compound may be either liquid or solid. By containing a phosphorus compound, thermal stability can be improved, and both good appearance and excellent thermal stability can be achieved.

Examples of the organic phosphate include mono- to tri-alkyl esters of phosphoric acid (for example, mono- to di-C _6-24 alkyl esters such as _monostearyl acid phosphate and distearyl acid phosphate), mono- to triaryl esters of phosphoric acid (mono- or di-C _6-10 aryl esters such as mono- or diphenyl phosphate), and the like.

Examples of the organic phosphite include bis(2,4-di-t-4 methylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite.

Examples of the organic phosphonate include mono- or di-alkyl phosphonates such as distearyl phosphonate (C _6-24 alkyl phosphonate, etc.); aryl phosphonates which may have a substituent on the aryl group such as diphenyl phosphonate and di(nonylphenyl)phosphonate (C _6-10 aryl phosphonate, etc.); and mono- or di-aralkyl phosphonates such as dibenzyl phosphonate ((C _6-10 aryl-C _1-6 alkyl) phosphonate, etc.).

An example of the organic phosphonite is tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphonite.

Examples of alkali metal phosphates include alkali metal salts such as phosphates or corresponding hydrogen phosphates (e.g., potassium phosphate, sodium phosphate [(sodium monophosphate (sodium dihydrogen phosphate), disodium phosphate (sodium hydrogen phosphate, sodium monohydrogen phosphate, disodium hydrogen phosphate), etc.)]).
Examples of alkaline earth metal phosphates include alkaline earth metal salts such as calcium phosphate [monocalcium phosphate (calcium dihydrogen phosphate, calcium bis(dihydrogen phosphate) monohydrate, etc.), secondary calcium phosphate (calcium hydrogen phosphate, calcium hydrogen phosphate dihydrate, etc.)], magnesium phosphate (magnesium hydrogen phosphate, magnesium dihydrogen phosphate, etc.), etc. The alkali metal salt or alkaline earth metal salt may be either anhydrous or hydrated.

Of these phosphorus compounds, it is preferable to use an organic phosphorus-based stabilizer from the viewpoint of superior appearance.

The content of the phosphorus compound is 0.1 to 1.0 parts by mass, more preferably 0.1 to 0.9 parts by mass, relative to 100 parts by mass of the total of the PBT resin and the PET resin. By setting the content of the phosphorus compound within the above range, the thermal stability can be further improved. When the phosphorus compound contains an inorganic phosphorus compound, the content of the inorganic phosphorus compound is preferably 0.2 to 0.8 parts by mass, more preferably 0.3 to 0.6 parts by mass, relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin. When the phosphorus compound contains an organic phosphorus compound, the content of the organic phosphorus compound is preferably 0.1 to 0.2 parts by mass, relative to 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin.

(Interesterification promoter)
The resin composition may contain an ester exchange promoter. By containing the ester exchange promoter, when the resin composition contains an inorganic phosphorus compound (such as an alkali metal phosphate or an alkaline earth metal phosphate) as a phosphorus compound, excellent appearance can be maintained.

Examples of the transesterification accelerator include antimony compounds such as antimony trioxide, antimony tetraoxide, antimony pentoxide, and sodium pyroantimonate; germanium compounds such as germanium dioxide and germanium tetroxide; titanium compounds such as titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate; dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethylditin oxide, cyclohexahexylditin oxide, didodecyltin oxide, triethyltin hydroxide, triphenyltin hydroxide, and triisobutyltin. Examples of the compounds include tin compounds such as acetate, dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, methylstannoic acid, ethylstannoic acid, and butylstannoic acid; magnesium compounds such as magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, and magnesium hydrogen phosphate; and calcium compounds such as calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide, and calcium hydrogen phosphate. In addition, examples of the compounds include alkaline earth metal compounds such as manganese compounds and zinc compounds. These compounds may be used alone or in combination of two or more.

The content of the transesterification promoter is preferably 0.01 to 2 parts by mass, more preferably 0.02 to 1 part by mass, and even more preferably 0.04 to 0.5 parts by mass, per 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin.

In one embodiment, when the resin composition contains an inorganic phosphorus compound as the phosphorus compound, it is preferable that the resin composition further contains an ester exchange promoter, and it is more preferable that the resin composition contains an antimony compound as the ester exchange promoter. For example, the resin composition can be configured to contain a polybutylene terephthalate resin, a polyethylene terephthalate resin, an inorganic phosphorus compound, and an antimony compound. In this case, the content of each component is as described above.

In one embodiment, when the resin composition contains an organic phosphorus compound as the phosphorus compound, the resin composition may be configured to contain no transesterification promoter or to have a transesterification promoter content of 0.01 mass% or less in the resin composition. Note that this description does not exclude the resin composition containing an organic phosphorus compound as the phosphorus compound from further containing a transesterification promoter.

(Halogen-based flame retardants)
The resin composition may be configured so that it does not contain a halogen-based flame retardant, or the content of the halogen-based flame retardant is 5% by mass or less, or 1% by mass or less in the total resin composition. The antimony compound used as the above-mentioned transesterification promoter may generally be added to a resin composition containing a polybutylene terephthalate resin as a flame retardant assistant used together with a halogen-based flame retardant. However, in this embodiment, the antimony compound is mainly intended to be used as a transesterification promoter rather than a flame retardant assistant, so the resin composition may not contain a halogen-based flame retardant. Note that this embodiment does not exclude the inclusion of a halogen-based flame retardant, and the resin composition may contain a known flame retardant such as a halogen-based flame retardant depending on the desired characteristics. When a halogen-based flame retardant is contained, the antimony compound can act as a flame retardant assistant in addition to acting as a transesterification promoter.

Examples of halogen-based flame retardants include organic halides, such as halogen-containing acrylic resins, halogen-containing styrene resins, halogen-containing polycarbonate resins, halogen-containing epoxy compounds, halogen-containing phenoxy resins, halogen-containing phosphate esters, halogen-containing triazine compounds, halogen-containing isocyanuric acid compounds, halogenated polyaryl ether compounds, and halogenated aromatic imide compounds.

(Other additives)
The resin composition may contain a superplasticizer to improve the flowability of the resin composition, if necessary. By improving the flowability, the moldability can be improved.
The high flow agent may be a polyhydric hydroxyl group-containing compound. As the polyhydric hydroxyl group-containing compound, a partial ester of a polyhydric alcohol and a fatty acid may be used, for example, glycerin mono-12-hydroxystearate, glycerin monostearate, triglycerin monostearate, pentaerythritol or dipentaerythritol fatty acid esters, etc., and one or more selected from these may be used.
The content of the superplasticizer is preferably 0.1 to 4.0 parts by mass, and more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the polyethylene terephthalate resin and the polyethylene terephthalate resin combined.

The resin composition may contain an inorganic filler as required. By containing an inorganic filler, it is possible to impart high mechanical strength to the resin composition.
Examples of inorganic fillers include fibrous fillers such as glass fiber, silica fiber, silica-alumina fiber, and alumina fiber; powdery fillers such as carbon black, silica, quartz powder, glass beads, calcium silicate, aluminum silicate, kaolin, talc, and calcium carbonate; and plate-like fillers such as mica, glass flakes, and various metal foils. The amount of inorganic filler added is not particularly limited, and is preferably 200 parts by mass or less, and more preferably 150 parts by mass or less, per 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin.

The resin composition may contain, within a range that does not impair the effects of the present invention, a release agent, an antioxidant, a weather stabilizer, a molecular weight regulator, an ultraviolet absorber, an antistatic agent, a dye, a pigment, a lubricant, a crystallization promoter, a crystal nucleating agent, a near infrared absorber, an organic filler, etc., but the additives are not limited to these. The content of the additives is not particularly limited, and can be 10 mass% or less, or 5 mass% or less in the resin composition.

(Crystallization Temperature)
The resin composition satisfies the following formula I and formula II.
Formula I: Crystallization temperature Tc1 (°C) ≦ 195°C
Formula II: Crystallization temperature Tc1 (°C) - crystallization temperature Tc3 (°C) ≦ 15°C
Tc1 in formulas I and II represents the peak temperature (°C) of the maximum endothermic peak of the DSC curve in differential scanning calorimetry (DSC) at the first temperature drop in a cycle test in which the temperature is raised from 40°C to 280°C at a temperature rise rate of 10°C/min and the temperature is lowered from 280°C to 40°C at a temperature drop rate of 10°C/min based on JIS K7121 for three cycles, and Tc3 in formula II represents the peak temperature (°C) of the maximum endothermic peak of the DSC curve in differential scanning calorimetry (DSC) at the third temperature drop in the cycle test. In formula I, the value of Tc1 is rounded off to one decimal place. Similarly, in formula II, the value of Tc1-Tc3 is rounded off to one decimal place.

Regarding formula I, the crystallization temperature Tc1 is 195° C. or less, preferably 190° C. or less, and more preferably 185° C. or less. By setting the crystallization temperature Tc1 to 195° C. or less, the appearance of the molded article can be improved.
Regarding formula II, the difference between the crystallization temperature Tc1 and the crystallization temperature Tc3 [crystallization temperature Tc1 (° C.)]-[crystallization temperature Tc3 (° C.)] is 15° C. or less, preferably 10° C. or less, and more preferably 5° C. or less. By making the difference between the crystallization temperature Tc1 and the crystallization temperature Tc3 15° C. or less, the thermal stability can be increased.

The crystallization temperatures Tc1 and Tc3 of the resin composition can be adjusted by adjusting the crystallization temperature and/or content of the PET resin, as well as by adjusting the type and/or content of the phosphorus compound and/or adding an additive (ester exchange promoter) that promotes the ester exchange reaction between the PBT resin and the PET resin.

For example, when the content of the phosphorus compound is reduced, the crystallization temperature Tc1 tends to be lower. Also, when an inorganic phosphorus compound is used as the phosphorus compound, the crystallization temperature Tc3 tends to be higher. Furthermore, when antimony trioxide is used as the transesterification promoter, the difference between the crystallization temperatures Tc1 and Tc3 tends to be larger.

Alternatively, the crystallization temperatures Tc1 and Tc3 of the resulting resin composition can be adjusted by devising a method for producing the resin composition, as will be described later.

(Application)
The resin composition can be used to produce molded articles having excellent appearance and excellent thermal stability, and can therefore be suitably used for molded articles that are exposed to the exterior of an automobile, such as interior and/or exterior parts, for example, door mirror stays, inner or outer door handles, ventilator fins, etc. The method for producing such molded articles is not particularly limited, and they can be formed by, for example, conventionally known injection molding, compression molding, etc.

[Production method]
The method for producing the resin composition is not particularly limited, and the resin composition can be produced using equipment and methods known in the art. For example, the necessary components are mixed and kneaded using a single-screw or twin-screw extruder or other melt kneading device to prepare pellets for molding. A plurality of extruders or other melt kneading devices may be used. All components may be simultaneously fed from a hopper, or some components may be fed from a side feed port.

In the method for producing a resin composition according to this embodiment, from the viewpoint of adjusting the crystallization temperatures Tc1 and Tc3 of the resulting resin composition by the production method, a polybutylene terephthalate resin and a polyethylene terephthalate resin can be heat-treated under conditions that satisfy the following formula III to obtain a resin mixture, and then the resin mixture and a phosphorus compound are mixed to obtain the resin composition.

Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s)
In the formula III, the temperature (° C.) is the temperature in the heating vessel or the extrusion temperature, and the time (s) is the time during which the resin is retained in the heating vessel.

By adding a phosphorus compound after heat-treating the PBT resin and the PET resin under conditions in which the product of the heat treatment temperature (°C) and time (s) is 12,000°C·s or more, it is possible to prevent Tc1 from becoming too high.
By adding a phosphorus compound after heat-treating the PBT resin and the PET resin under conditions where the product of the heat treatment temperature (°C) and time (s) is 180,000°C·s or less, it is possible to prevent the viscosity from decreasing too much due to decomposition.
The flow rate Q (kg/h) of the resin when heat treating the PBT resin and the PET resin can be, for example, 10 to 20 kg/h, and the rotation speed N (rpm) can be, for example, 100 to 150 rpm.

The conditions for mixing the resin mixture containing the PBT resin and the PET resin with the phosphorus compound are not particularly limited, and for example, the mixture can be melt-kneaded for 60 to 240 seconds at a temperature 10 to 30° C. higher than the melting point of the PBT resin or the PET resin measured with a differential scanning calorimeter.
The flow rate Q (kg/h) of the resin during melt kneading can be, for example, 10 to 20 kg/h, and the rotation speed N (rpm) can be, for example, 100 to 150 rpm.

The method of heat-treating the PBT resin and the PET resin in advance to obtain a resin mixture, and the method of mixing the resin mixture and the phosphorus compound are not particularly limited, and can be performed using a known extruder or melt kneading device. The step of obtaining a resin mixture by heat treatment is usually performed while heating and kneading (heat mixing), and a resin alloy of the PBT resin and the PET resin is obtained. The step of heat-treating the PBT resin and the PET resin to obtain a resin mixture (hereinafter also referred to as the "heat treatment step") and the step of mixing the resin mixture and the phosphorus compound to obtain a resin composition (hereinafter also referred to as the "melt kneading step") may be a series of steps or may be separate steps.

An example of a method in which the heat treatment step and the melt-kneading step are performed as a continuous step is a method in which PBT resin and PET resin are heat-treated by melting and retaining them in a heating container using a plastomill or the like, and then a phosphorus compound is added to the heating container and melt-kneaded to obtain a resin composition.

An example of a method in which the heat treatment step and the melt kneading step are separate steps is to melt-extrude a PBT resin and a PET resin using an extruder to obtain composition pellets containing the PBT resin and the PET resin, and then melt-knead the composition pellets with a phosphorus compound using an extruder or a melt kneading device to obtain a resin composition. The number of times that the PBT resin and the PET resin are melt-extruded in the heat treatment step can be selected from the viewpoint of the intrinsic viscosity of the obtained composition, and can be, for example, 1 to 10 times.

The timing of adding other resins, inorganic fillers and/or other additives is not particularly limited, and they may be added to the resin composition in a process in which the PBT resin and PET resin are previously heat-treated, or they may be added to the resin composition in a process in which a phosphorus compound is added and melt-kneaded.

In one embodiment, the manufacturing method may be configured to include the following steps.
i) mixing a polybutylene terephthalate resin and a polyethylene terephthalate resin to obtain a resin mixture;
ii) heat treating the resin mixture under conditions that satisfy the following formula III:
Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s)
iii) mixing the heat-treated resin mixture with a phosphorus compound;

The method for mixing the resins in step i) is not particularly limited, and can be carried out using, for example, a known stirring mixer, extruder, melt kneader, or the like.
The method of heat treatment in step ii) and the method of mixing the resin mixture with the phosphorus compound in step iii) can be performed in the same manner as the method of previously heat treating a PBT resin and a PET resin to obtain a resin mixture and the method of mixing a resin mixture with a phosphorus compound, respectively, as already described.

[Molding]
The molded article according to the present embodiment is a molded article molded using the above-mentioned resin composition. Since the molded article uses the above-mentioned resin composition, it has excellent appearance and excellent thermal stability. Since it has excellent thermal stability, it is possible to suppress deterioration of moldability and deterioration of physical properties after melt molding. Since the molded article has excellent appearance and thermal stability, it can be suitably used as a molded article exposed to the exterior surface of an automobile interior part and/or an automobile exterior part, such as a door mirror stay, an inner/outer door handle, a ventilator fin, etc. The manufacturing method of the molded article is not particularly limited, and it can be formed by, for example, conventionally known injection molding, compression molding, etc.

The present invention will be described in more detail below by showing examples, but the interpretation of the present invention is not limited to these examples.

The materials used in the examples and comparative examples are as follows.
Polybutylene terephthalate resin (PBT): manufactured by Chang Chun Ohka Co., Ltd., IV = 0.77
Polyethylene terephthalate resin (PET): manufactured by Guangdong IVL PET Polymer Co., Ltd., IV=0.76
Organic phosphorus compound: bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, manufactured by ADEKA Corporation, "ADEKA STAB PEP36"
Inorganic phosphorus compound: sodium dihydrogen phosphate, manufactured by Yoneyama Chemical Industry Co., Ltd., "sodium phosphate monobasic"
Antimony trioxide: "PATOX-M" manufactured by Nihon Seiko Co., Ltd.
Glass fiber: Nippon Electric Glass Co., Ltd., "ECS03T-187"
Carbon black: Mitsubishi Chemical Corporation, "#750B"
Superplasticizer: Glycerin mono-12-hydroxystearate, manufactured by Riken Vitamin Co., Ltd., "Rikemal HC-100"
Release agent: Pentaerythritol stearate, NOF Corporation, "Unistar H476"

[Example 1, Comparative Examples 1 to 3]
The components shown in Table 1 were blended in the composition (parts by mass) shown in Table 1, and fed from a hopper to a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) having a screw of 30 mmφ, and melt-kneaded at a cylinder temperature of 260° C. for a residence time of 50 seconds to obtain a pellet-shaped PBT resin composition. [Example 2]
PBT and PET were blended in the composition (parts by mass) shown in "Heat treatment 1" in Table 1, fed from a hopper to a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) having a 30 mmφ screw, and melt-kneaded at the temperature shown in Table 1 to obtain a pellet-shaped resin composition. The obtained resin composition was blended with the components shown in "Heat treatment 2" in Table 1 in the composition (parts by mass) shown in "Heat treatment 2" in Table 1, and melt-kneaded in the same extruder at a cylinder temperature of 260°C for a residence time of 50 seconds to obtain a pellet-shaped resin composition.

[Examples 3 to 5, Comparative Examples 4 to 13]
A resin composition was obtained in the same manner as in Example 2, except that the composition, heat treatment conditions, and melt-kneading conditions were as shown in Table 1.

[Example 6]
PBT and PET were blended in the composition (parts by mass) shown in Table 1, and melt-kneaded for 10 minutes at a cylinder temperature of 280° C. and a screw rotation speed of 100 rpm using a Labo Plastomill manufactured by Toyo Seiki Co., Ltd. After kneading, a phosphorus compound was added to obtain the composition (parts by mass) shown in Table 1, and kneaded for 2 minutes to obtain a resin composition.

[Example 7]
A resin composition was obtained in the same manner as in Example 6, except that the heat treatment conditions and melt-kneading conditions in Table 1 were used.

[Physical Properties]
(Crystallization temperatures Tc1, Tc3)
Using the resin composition obtained above, three cycles of heating from 40°C to 280°C at a heating rate of 10°C/min and cooling from 280°C to 40°C at a cooling rate of 10°C/min were performed by DSC (differential scanning calorimetry) based on JIS K7121. The peak temperature (°C) of the maximum endothermic peak in the DSC curve during the first cooling cycle was determined as Tc1, and the peak temperature (°C) of the maximum endothermic peak in the DSC curve during the third cooling cycle was determined as Tc3. The results are shown in Table 1.
In addition, the examples and comparative examples in Table 1 are compositions of PBT and PET alloy, and those in which two peaks of the melting point Tm were observed are listed as upper and lower rows. Also, only one peak was confirmed for the crystallization temperature Tc in each case.

(Intrinsic Viscosity: IV)
The intrinsic viscosity (IV) of the resin composition obtained above was measured using a mixed solvent of phenol/tetrachloroethane (mass ratio 60/40) at 35° C. with an Ubbelohde viscometer. The results are shown in Table 1.

[evaluation]
(Appearance)
Each of the resin compositions of the Examples and Comparative Examples obtained above was dried at 140°C for 3 hours, and then an automobile outer door handle escutcheon model shown in Figure 1 (with the exterior surface embossed according to Tanazawa Hakkosha Co., Ltd.'s TH-113 embossing standard) was injection molded using an SG-150U SYCAP-MIV manufactured by Sumitomo Heavy Industries, Ltd. under conditions of a cylinder temperature of 265°C, a mold temperature of 95°C, an injection speed of 35 mm/s, and a holding pressure of 80 MPa. The molded product was visually observed for the transfer state of the embossing at the stage when the molding stabilized after about 10 shots from the start of molding. The observation results were evaluated according to the following criteria. The results are shown in Table 1.
Good: Good transfer condition was confirmed over the entire textured surface. Bad: Uneven transfer of the texture was observed.

(Thermal Stability)
The value of ΔTc (Tc1-Tc3) was calculated from the crystallization temperatures Tc1 and Tc3 measured above, and the thermal stability was evaluated according to the following criteria. The results are shown in Table 1.
Good: Tc1-Tc3≦15°C
Bad: Tc1-Tc3>15°C

As shown in Table 1, the molded articles using the resin compositions obtained in the Examples have excellent appearance and thermal stability.

1 Molded products

Claims (11)

The composition contains a total of 100 parts by mass of polybutylene terephthalate resin and polyethylene terephthalate resin, and 0.1 to 1.0 part by mass of a phosphorus compound, and is represented by the following formulas I and II:
Formula I: Crystallization temperature Tc1 (°C) ≦ 195°C
Formula II: [Crystallization temperature Tc1 (°C)] - [Crystallization temperature Tc3 (°C)] ≦ 15°C
(In the formula, Tc1 represents the peak temperature (° C.) of the maximum endothermic peak in the DSC curve in differential scanning calorimetry (DSC) during the first temperature drop cycle when three cycles of heating from 40° C. to 280° C. at a heating rate of 10° C./min and cooling from 280° C. to 40° C. at a heating rate of 10° C./min are performed according to JIS K7121, and Tc3 represents the peak temperature (° C.) of the maximum endothermic peak in the DSC curve in differential scanning calorimetry (DSC) during the third temperature drop cycle.)
The filling,
Further containing an ester exchange promoter containing antimony trioxide ,
The content of the transesterification promoter is 0.01 to 2 parts by mass per 100 parts by mass of the polybutylene terephthalate resin and the polyethylene terephthalate resin combined. The resin composition according to claim 1, wherein the content of the polyethylene terephthalate resin is 50 to 80 parts by mass per 100 parts by mass of the polybutylene terephthalate resin. The resin composition according to claim 1 or 2, which is used in the manufacture of interior and/or exterior automotive parts. The phosphorus compound contains an organic phosphorus compound,
The resin composition according to any one of claims 1 to 3, wherein the content of the organic phosphorus compound is 0.1 to 0.2 parts by mass per 100 parts by mass of the total of the polybutylene terephthalate resin and the polyethylene terephthalate resin. The resin composition according to any one of claims 1 to 4, which does not contain a halogen-based flame retardant or contains 5 mass% or less of a halogen-based flame retardant in the entire resin composition. A method for producing the resin composition according to any one of claims 1 to 5,
A method for producing a resin composition, comprising heat treating a polybutylene terephthalate resin and a polyethylene terephthalate resin under conditions that satisfy the following formula III to obtain a resin mixture, and mixing the resin mixture with a phosphorus compound to obtain a resin composition.
Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s) The method according to claim 6, in which the polybutylene terephthalate resin and the polyethylene terephthalate resin are heat-treated by melting and retaining them in a heating vessel, and then a phosphorus compound is added to the heating vessel and mixed with heating to obtain a resin composition. The manufacturing method according to claim 6, in which a heat-treated resin mixture is obtained by melt-extruding a polybutylene terephthalate resin and a polyethylene terephthalate resin, and then the resin mixture is heated and mixed with a phosphorus compound to obtain a resin composition. A method for producing the resin composition according to any one of claims 1 to 5,
mixing a polybutylene terephthalate resin and a polyethylene terephthalate resin to obtain a resin mixture;
Heat treating the resin mixture under conditions that satisfy the following formula III:
Formula III: 12000 (°C·s) ≦ Temperature (°C) × Time (s) ≦ 180000 (°C·s)
and mixing the heat-treated resin mixture with a phosphorus compound. A molded article using the resin composition according to any one of claims 1 to 5. The molded product according to claim 10, which is an interior or exterior part for an automobile.

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