Molded article, manufacturing method of molded article, and method for improving hydrolysis resistance

Abstract

To provide a molding having improved hydrolysis resistance.SOLUTION: A molding comprises a polyester resin composition comprising at least a polyester thermoplastic resin A with an inherent viscosity of 1.2 dL / g or less, inorganic filler B, and a thermoplastic resin C excluding the polyester thermoplastic resin. The inorganic filler B is covered with the thermoplastic resin C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molded article having hydrolysis resistance for use in home appliances, automobiles, etc., and relates to a molded article containing a polyester-based thermoplastic resin having hydrolysis resistance superior to that of existing materials, a method for producing the molded article, and a method for improving hydrolysis resistance. [Background technology]

[0002] Molded products made from polyester thermoplastic resins have excellent mechanical properties, electrical properties, heat resistance, weather resistance, water resistance, chemical resistance, and solvent resistance, and are therefore widely used as engineering plastics in a variety of applications, including automotive parts and electrical and electronic parts.

[0003] However, polyester-based thermoplastic resins have the disadvantage that their physical properties are easily deteriorated due to hydrolysis in high-temperature, high-humidity environments because they contain ester groups in their molecules, and therefore do not necessarily have sufficient durability when used in high-temperature, high-humidity environments.

[0004] Studies are being conducted to improve hydrolysis resistance from the perspective of materials. For example, Patent Document 1 proposes a resin composition for insert molding that contains polybutylene terephthalate, a glycidyl group-containing copolymer having copolymerization components of an α-olefin and an α,β-unsaturated glycidyl ester, an ethylene-α-olefin copolymer, and reinforcing fibers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-196484 Summary of the Invention [Problem to be solved by the invention]

[0006] Although the above-mentioned techniques have been effective in improving hydrolysis resistance, the required level of hydrolysis resistance has increased in recent years, and further improvements are required.

[0007] An object of the present invention is to provide a molded article containing a polyester-based thermoplastic resin that exhibits higher hydrolysis resistance than ever before, a method for producing such a molded article, and a method for improving hydrolysis resistance. [Means for solving the problem]

[0008] The object of the present invention has been achieved by the following. 1. A molded article made of a polyester resin composition containing at least a polyester thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester thermoplastic resin A, wherein the inorganic filler B is coated with the thermoplastic resin C. 2. The molded article described in Senki 1, wherein the intrinsic viscosity of the polyester-based thermoplastic resin A is 0.6 dL / g or more. 3. The molded article according to 1 or 2 above, wherein the thermoplastic resin C and the inorganic filler B have affinity with each other. 4. The molded article according to any one of 1 to 3 above, wherein the polyester-based thermoplastic resin A has a carboxylic acid terminal concentration of 0.5 to 30 meq / kg. 5. A molded article according to any one of claims 1 to 4, wherein the polyester resin composition further contains a compound D for improving water resistance that is reactive with the carboxylic acid terminal group of the polyester thermoplastic resin A. 6. A method for producing a molded article having improved hydrolysis resistance from a polyester resin composition containing at least a polyester thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester thermoplastic resin, the method comprising melt-kneading the inorganic filler B and the thermoplastic resin C in advance to coat the inorganic filler B with the thermoplastic resin C, and then melt-kneading the inorganic filler B with the thermoplastic resin C and the polyester thermoplastic resin A. 7. A method for improving the hydrolysis resistance of a polyester resin composition containing at least a polyester thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester thermoplastic resin A, the method comprising melt-kneading the inorganic filler B and the thermoplastic resin C in advance to coat the inorganic filler B with the thermoplastic resin C, and then melt-kneading the inorganic filler B with the thermoplastic resin C and the polyester thermoplastic resin A. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a molded article having better hydrolysis resistance than ever before. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an electron microscope (×20,000 magnification) photograph of a cross section of a molded article of Example 2 of the present invention. [Figure 2] 1 is an electron microscope (×20,000 magnification) photograph of a cross section of a molded article containing an inorganic filler that is not surface-coated, which is one embodiment of the present invention. [Figure 3] 1 is an electron microscope (×20,000 magnification) photograph of a cross section of a molded article of Comparative Example 2. [Figure 4] 1 is a schematic view of an extruder according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The hydrolysis-resistant molded article of the present invention is a hydrolysis-resistant molded article made of a resin composition containing at least a polyester-based thermoplastic resin A, an inorganic filler B, and a thermoplastic resin C other than the polyester-based thermoplastic resin A, and is characterized in that the inorganic filler B is coated with the olefin-based elastomer B.

[0012] <Polyester-based thermoplastic resin A> The polyester resin-based thermoplastic A is a thermoplastic polyester resin obtained by reacting a dicarboxylic acid component mainly composed of a dicarboxylic acid compound and / or its ester-forming derivative with a diol component mainly composed of a diol compound and / or its ester-forming derivative, and at least one of the dicarboxylic acid component and the diol component contains an aromatic compound.

[0013] Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids (e.g., about C4-40 dicarboxylic acids, preferably about C4-14 dicarboxylic acids, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, hexadecanedicarboxylic acid, and dimer acid), alicyclic dicarboxylic acids (e.g., about C4-40 dicarboxylic acids, preferably about C8-12 dicarboxylic acids, such as hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and hymic acid), and aromatic dicarboxylic acids. Examples of the dicarboxylic acid include dicarboxylic acids (for example, phthalic acid, isophthalic acid, terephthalic acid, methyl isophthalic acid, methyl terephthalic acid, naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, and dicarboxylic acids having about C8 to C16, such as 4,4'-biphenyldicarboxylic acid, 4,4'-diphenoxyetherdicarboxylic acid, 4,4'-dioxybenzoic acid, 4,4'-diphenylmethanedicarboxylic acid, and 4,4'-diphenylketonedicarboxylic acid), and derivatives thereof (for example, derivatives capable of forming esters such as lower alkyl esters, aryl esters, and acid anhydrides).

[0014] These dicarboxylic acid components can be used alone or in combination. Preferred dicarboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid (particularly terephthalic acid and 2,6-naphthalenedicarboxylic acid). The dicarboxylic acid component preferably contains, for example, 50 mol % or more, preferably 80 mol % or more, and more preferably 90 mol % or more of aromatic dicarboxylic acids.

[0015] Furthermore, if necessary, polycarboxylic acids such as trimellitic acid and pyromellitic acid or ester-forming derivatives thereof (alcohol esters, etc.) may be used in combination. The use of such polyfunctional compounds in combination also makes it possible to obtain a branched thermoplastic polyester resin.

[0016] Examples of diol components include aliphatic alkanediols (e.g., C2-C12 aliphatic diols such as ethylene glycol, trimethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, hexanediol, octanediol, and decanediol, preferably C2-C10 aliphatic diols), polyoxyalkylene glycols (glycols having an alkylene group of C2-C4 and multiple oxyalkylene units, such as diethylene glycol, dipropylene glycol, ditetramethylene glycol, triethylene glycol, tripropylene glycol, and polytetramethylene glycol), and alicyclic diols (e.g., 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A).

[0017] Additionally, aromatic diols such as hydroquinone, resorcinol, bisphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis-(4-(2-hydroxyethoxy)phenyl)propane, and xylylene glycol may be used in combination. These diol components may be used alone or in combination.

[0018] Preferred diol components include C2-10 alkylene glycols (straight-chain alkylene glycols such as ethylene glycol, trimethylene glycol, propylene glycol, and 1,4-butanediol).

[0019] The diol component preferably contains, for example, 50 mol% or more, preferably 80 mol% or more, and more preferably 90 mol% or more of C2-10 alkylene glycol. Furthermore, if necessary, polyols such as glycerin, trimethylolpropane, trimethylolethane, and pentaerythritol, or their ester-forming derivatives, may be used in combination. The use of such polyfunctional compounds in combination also allows for the production of branched polyester resins.

[0020] As the polyester-based thermoplastic resin A, a copolyester that combines two or more of the above-mentioned dicarboxylic acid components and diol components, or a copolyester that further combines an oxycarboxylic acid component, a lactone component, etc. as another copolymerizable monomer (hereinafter sometimes referred to as a copolymerizable monomer) can also be used.

[0021] Examples of the hydroxycarboxylic acid (or hydroxycarboxylic acid component or hydroxycarboxylic acids) include hydroxycarboxylic acids such as hydroxybenzoic acid, hydroxynaphthoic acid, hydroxyphenylacetic acid, glycolic acid, and hydroxycaproic acid, as well as derivatives thereof. Examples of the lactone include C3-12 lactones such as propiolactone, butyrolactone, valerolactone, and caprolactone (e.g., ε-caprolactone).

[0022] In the copolyester, the proportion of the copolymerizable monomer can be selected, for example, from the range of about 0.01 mol% to about 30 mol%, and is usually about 1 mol% to about 30 mol%, preferably about 3 mol% to about 25 mol%, and more preferably about 5 mol% to about 20 mol%.

[0023] Furthermore, when a homopolyester and a copolyester are used in combination, the ratio of the homopolyester to the copolyester is such that the proportion of the copolymerizable monomer relative to the total monomers is in the range of 0.1 mol% to 30 mol% (preferably approximately 1 mol% to 25 mol%, and more preferably approximately 5 mol% to 25 mol%), and can usually be selected within the range of homopolyester / copolyester = 99 / 1 to 1 / 99 (mass ratio), preferably 95 / 5 to 5 / 95 (mass ratio), and more preferably approximately 90 / 10 to 10 / 90 (mass ratio).

[0024] Preferred polyester-based thermoplastic resins A include homopolyesters or copolyesters containing alkylene arylate units such as alkylene terephthalate or alkylene naphthalate as the main component (e.g., about 50 to 100 mol %, preferably about 75 to 100 mol %) [e.g., homopolyesters such as polyalkylene terephthalate (e.g., polyC2-4 alkylene terephthalate such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT)), 1,4-cyclohexanedimethylene terephthalate (PCT), polyalkylene naphthalate (e.g., polyC2-4 alkylene naphthalate such as polyethylene naphthalate, polypropylene naphthalate, polybutylene naphthalate); and copolyesters containing alkylene terephthalate and / or alkylene naphthalate units as the main component (e.g., 50 mol % or more)], and these can be used alone or in combination of two or more.

[0025] Particularly preferred polyester-based thermoplastic resins A are homopolyester resins or copolyester resins containing 80 mol % or more (particularly 90 mol % or more) of C2-4 alkylene arylate units such as ethylene terephthalate, trimethylene terephthalate, tetramethylene terephthalate, and tetramethylene-2,6-naphthalate (e.g., polyethylene terephthalate resin, polytrimethylene terephthalate resin, polybutylene terephthalate resin, polytetramethylene-2,6-naphthalenedicarboxylate resin, etc.).

[0026] Of these, polyethylene terephthalate resin and polybutylene terephthalate resin are preferred, with polybutylene terephthalate resin being particularly preferred.

[0027] The intrinsic viscosity IV of the polyester thermoplastic resin A of the present invention is 1.2 dL / g or less, preferably 0.6 dL / g or more, more preferably 0.7 to 1.0 dL / g, and even more preferably 0.7 to 0.9 dL / g.

[0028] If the intrinsic viscosity is lower than 0.6, the strength and toughness will decrease significantly due to hydrolysis, and if it exceeds 1.2 dL / g, the thermoplastic resin C may peel off from the inorganic filler B coated with the thermoplastic resin C during kneading, resulting in a loss of effectiveness. The intrinsic viscosity can also be adjusted by blending polyester-based thermoplastic resins with different intrinsic viscosities.

[0029] For example, a polyester thermoplastic resin with an intrinsic viscosity of 0.9 dL / g can be prepared by blending a polyester thermoplastic resin with an intrinsic viscosity of 1.0 dL / g with a polyester thermoplastic resin with an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity (IV) of the polyester thermoplastic resin can be measured in o-chlorophenol at 35°C.

[0030] The carboxylic acid terminal concentration of the polyester-based thermoplastic resin A is preferably 0.5 to 30 meq / kg, more preferably 0.5 to 25 meq / kg, and even more preferably 0.5 to 12 meq / kg. To achieve this range of carboxylic acid terminal concentration, a high-molecular-weight polymer having fewer terminal groups of the polyester-based thermoplastic resin may be used, or a melt-polymerized product having an intrinsic viscosity IV of about 0.1 to 0.8 dL / g may be polymerized by solid-phase polymerization.

[0031] When solid-state polymerization is used, it is desirable to treat at a low temperature for a long time because a high treatment temperature increases the number of terminal carboxyl groups. This can usually be adjusted to, for example, 120 to 220°C, preferably 140 to 200°C, and more preferably 150 to 190°C under reduced pressure or in an inert gas atmosphere.

[0032] The carboxylic acid terminal concentration was determined by dissolving a pulverized sample of polyester thermoplastic resin pellets obtained by polymerization in benzyl alcohol at 215° C. for 10 minutes, and then titrating it with a 0.01 N aqueous sodium hydroxide solution.

[0033] <Inorganic filler B> Examples of the inorganic filler B to be contained in the molded article of the present invention include a fibrous filler, a plate-like filler, and a granular filler.

[0034] Examples of fibrous fillers include inorganic fibers such as glass fibers, asbestos fibers, carbon fibers, silica fibers, alumina fibers, silica-alumina fibers, aluminum silicate fibers, zirconia fibers, potassium titanate fibers, silicon carbide fibers, and whiskers (whiskers of silicon carbide, alumina, silicon nitride, etc.).

[0035] Examples of the plate-like filler include talc, mica, glass flakes, graphite, etc. Examples of the powdery filler include glass beads, glass powder, milled fiber (e.g., milled glass fiber), wollastonite, etc.

[0036] The average diameter of the fibrous filler may be, for example, about 1 μm to 30 μm (preferably 5 μm to 20 μm, more preferably 10 to 15 μm), and the average length may be, for example, about 100 μm to 5 mm (preferably 300 μm to 4 mm, more preferably 500 μm to 3.5 mm).

[0037] The average primary particle size of the plate-like or granular filler can be, for example, about 0.1 μm to 500 μm, and preferably about 1 μm to 100 μm. These inorganic fillers can be used alone or in combination of two or more.

[0038] The average diameter and length of the fibrous filler and the average primary particle diameter of the plate-like or granular filler are values ​​calculated by analyzing images of the fibrous filler, plate-like or granular filler before being blended into the resin composition, taken with a CCD camera, and calculating the weighted average. These values ​​can be calculated, for example, using a dynamic image analysis / particle (state) analyzer PITA-3 manufactured by Seishin Enterprise Co., Ltd. The aspect ratio of the plate-like or granular filler is not particularly limited and can be, for example, 1 or more and 10 or less.

[0039] The inorganic filler B also includes flame retardants, catalysts, colorants, etc. that accelerate the thermal degradation and hydrolysis of the polyester thermoplastic resin A.

[0040] Examples of flame retardants include organic halogen-based flame retardants such as hexabromobenzene, decabromodiphenyl ether, tetrabromobisphenol A, halogenated bisimide compounds, polycarbonate oligomers containing units derived from halogenated bisphenol A, diepoxy compounds which are reaction products of halogenated bisphenol A and epichlorohydrin, halogenated polystyrene, halogenated acrylic polymers, and pentabromopolybenzyl acrylate.

[0041] Examples of inorganic colorants include titanium-based pigments, zinc-based pigments, carbon black (furnace black, channel black, acetylene black, ketjen black, etc.), iron-based pigments, molybdenum-based pigments, cadmium-based pigments, lead-based pigments, cobalt-based pigments, and aluminum-based pigments. Examples of organic colorants include azo-based pigments, anthraquinone-based pigments, phthalocyanine-based pigments, quinacridone-based pigments, perylene-based pigments, perinone-based pigments, isoindoline-based pigments, dioxazine-based pigments, and threne-based pigments.

[0042] <Thermoplastic resin C> The thermoplastic resin C of the present invention is preferably a resin that can coat the inorganic filler B and has superior hydrolysis resistance compared to the polyester-based thermoplastic resin A.

[0043] Examples of resins with excellent hydrolysis resistance include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyvinyl acetal resin, ethylene-vinyl acetate copolymer (EVA) resin, polyvinyl alcohol resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), elastomers, etc. Elastomers with particularly excellent toughness are preferred.

[0044] Examples of elastomers include olefin-based elastomers, styrene-based elastomers, and silicone-based elastomers. Specifically, ethylene ethyl acrylate (EEA) copolymers, methacrylate-butylene-styrene (MBS) copolymers, and ethylene glycidyl methacrylate (EGMA) copolymers can be used. Polyester-based elastomers are unsuitable due to their poor hydrolysis resistance.

[0045] The olefin-based elastomer is a copolymer containing ethylene and / or propylene as a component, and specific examples thereof include ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-diene copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-glycidyl methacrylate copolymer, etc., but are not limited to these. Most preferred are epoxy group-containing olefin-based copolymers that have groups reactive with inorganic fillers.

[0046] Furthermore, among olefin-based elastomers, graft copolymers can also be used in which one or more polymers or copolymers composed of repeating units represented by the following general formula (1) are chemically bonded in a branched or crosslinked structure to an ethylene-unsaturated carboxylic acid alkyl ester copolymer or an olefin-based copolymer composed of an α-olefin and a glycidyl ester of an α,β-unsaturated acid.

[0047] [ka] (wherein R represents hydrogen or a lower alkyl group, and X represents one or more groups selected from -COOCH3, -COOC2H5, -COOC4H9, -COOCH2CH(C2H5)C4H9, -C6H5, and -CN)

[0048] As the α-olefin, a C2-4 olefin such as ethylene or propylene can be used, with ethylene or propylene being preferred. As the α,β-unsaturated acid glycidyl ester, glycidyl acrylate or glycidyl methacrylate is preferred. In addition, a third component such as a C1-12 (meth)acrylic acid ester or vinyl acetate may be copolymerized.

[0049] The olefin and glycidyl ester can be adjusted to a range of 30 to 90 mol % or 70 to 10 mol % in the copolymer, and the third component can be contained in a range of 0 to 30 mol %.

[0050] In the present invention, ethylene-glycidyl methacrylate copolymer (hereinafter also referred to as EGMA) is particularly preferred. The ratio of glycidyl methacrylate to ethylene is not particularly limited, but the ratio is preferably in the range of 1 to 30 parts by mass, preferably 3 to 20 parts by mass, and more preferably 8 to 15 parts by mass, based on 100 parts by mass of the copolymer, when the modified sites of the copolymer are converted into the mass of each monomer.

[0051] Examples of styrene-based elastomers include block or graft copolymers (or hydrogenated products thereof) of hard segments composed of a homopolymer or copolymer of an aromatic vinyl monomer such as styrene, α-methylstyrene, or vinyltoluene, and soft segments composed of a homopolymer or copolymer of at least one monomer selected from α-olefins (α-C2-12 olefins such as ethylene, propylene, 1-butene, 1-hexene, and 1-octene) and diene monomers (butadiene, isoprene, etc.).

[0052] The styrene-based elastomer may also be an elastomer having a reactive functional group, such as an acid-modified elastomer modified with an acid or acid anhydride, such as (meth)acrylic acid or maleic anhydride, or an epoxy-modified elastomer obtained by using a copolymerizable monomer having a glycidyl group or an epoxy group (such as glycidyl (meth)acrylate) or by epoxidizing the unsaturated bond of an elastomer.

[0053] Representative styrene-based elastomers include styrene-diene-styrene block copolymers [styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), etc.], hydrogenated block copolymers [styrene-ethylene-butylene-styrene block copolymer (or hydrogenated (styrene-butadiene-styrene block copolymer)) (SEBS), styrene-ethylene-propylene-styrene block copolymer (or hydrogenated (styrene-isoprene-styrene block copolymer)) (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), hydrogenated polymers of random styrene-butadiene copolymers, etc.], and modified copolymers in which functional groups (epoxy groups, carboxyl groups, acid anhydride groups, etc.) have been introduced into these copolymers [epoxidized styrene-diene copolymers in which the unsaturated bonds of the diene have been epoxidized (epoxidized styrene-diene-styrene block copolymers or their hydrogenated polymers, etc.)].

[0054] Silicone elastomers are elastomers containing organopolysiloxane as the main component, and are divided into polydimethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. A portion of the organopolysiloxane may be modified with a vinyl group, an alkoxy group, or the like. Specific examples of silicone elastomers include silicone rubber (poly(dimethylsiloxane) and poly(dimethylsiloxane-co-methylvinylsiloxane)).

[0055] Commercially available silicone elastomers include the KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, and SH series (all manufactured by Toray Dow Corning Silicone Co., Ltd.).

[0056] The inorganic filler B of the present invention is characterized in that its surface is coated with a thermoplastic resin C. Whether or not it is coated can be determined by observing the cross section of a molded article with an SEM, or by the following method (hereinafter also referred to as a coating confirmation method).

[0057] Inorganic filler B coated with thermoplastic resin C can be produced by a coating process in which thermoplastic resin C and inorganic filler B are melt-kneaded. This inorganic filler B, whose surface is coated with thermoplastic resin C, is melt-kneaded with thermoplastic resin A. The thermoplastic resin A not involved in the coating and excess thermoplastic resin C are removed using a solvent that can dissolve both thermoplastic resin A and thermoplastic resin C. The coated inorganic filler B is then measured by FT-IR.

[0058] When absorption due to thermoplastic resin C is observed in FT-IR compared with an inorganic filler that has not been coated, it is clear that inorganic filler B is coated with thermoplastic resin C.

[0059] The resin composition for molded articles can be produced by going through a production step in which the surface of inorganic filler is coated with thermoplastic resin C, then adding thermoplastic resin A, and further melt-kneading the mixture.

[0060] For example, inorganic filler B and thermoplastic resin C may first be melt-kneaded in an extruder, pelletized to form a masterbatch, and then polyester thermoplastic resin A and the masterbatch may be melt-kneaded again to form pellets, which may then be produced in an injection molding machine. Alternatively, the masterbatch and polyester thermoplastic resin A may be blended in any ratio, and then directly charged into an injection molding machine to produce the masterbatch.

[0061] Alternatively, a method without masterbatching may be used, for example, by feeding inorganic filler B and thermoplastic resin C into an extruder and melt-kneading them, then feeding polyester-based thermoplastic resin A and melt-kneading them, pelletizing them, and then injection molding them. In this case, kneading may be performed using a so-called tandem extruder. Tandem extruders allow for detailed setting of the number of screws used in each barrel, the kneading pattern, the kneading temperature, and the like.

[0062] Using this method, a molded article can be obtained in which inorganic filler B coated with thermoplastic resin C is dispersed in thermoplastic resin A. Thermoplastic resin C may be added to the coated thermoplastic resin C during melt-kneading with thermoplastic resin A.

[0063] In the present invention, the inorganic filler B is contained in an amount of preferably 20 to 200 parts by mass, more preferably 30 to 160 parts by mass, per 100 parts by mass of the thermoplastic resin A.

[0064] In the present invention, inorganic filler BN, which is not surface-coated, can also be blended in addition to inorganic filler B, the surface of which is coated with thermoplastic resin C. The blending amount is appropriately selected depending on the desired mechanical properties, but it can be contained in an amount of 0 to 200 parts by mass per 100 parts by mass of thermoplastic resin A.

[0065] In the present invention, it is preferable that the thermoplastic resin C has affinity with the inorganic filler B. Here, affinity refers to the degree to which the thermoplastic resin C does not peel off from the surface of the inorganic filler B during melt-kneading, such as molding, of the resin composition.

[0066] For example, the thermoplastic resin C may contain a functional group reactive with the inorganic filler B, or the inorganic filler B may be treated with a surface treatment agent to reduce the hydrophobicity of the inorganic filler B or to promote reaction or hydrogen bonding with the functional group of the thermoplastic resin C. Alternatively, a thermoplastic resin C having a higher viscosity than the polyester thermoplastic resin A may be selected to reduce shear deformation of the thermoplastic resin C during melt-kneading with the polyester thermoplastic resin A.

[0067] <Compound D for improving hydrolysis resistance> The resin composition of the present invention may contain a compound D for improving water resistance. The compound D for improving water resistance is a compound having a group reactive with the polyester-based thermoplastic resin A, and is preferably an epoxy compound, a carbodiimide compound, an oxazoline compound, or the like.

[0068] A carbodiimide compound is a compound having a carbodiimide group (-N=C=N-) in the molecule. As the carbodiimide compound, any of an aliphatic carbodiimide compound having an aliphatic main chain, an alicyclic carbodiimide compound having an alicyclic main chain, and an aromatic carbodiimide compound having an aromatic main chain can be used, but aromatic carbodiimide compounds are preferred in terms of hydrolysis resistance.

[0069] Examples of aliphatic carbodiimide compounds include diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-tert-butylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, 1-(2-butyl)-3-ethylcarbodiimide, 1,3-di-(2-butyl)carbodiimide, poly(diisopropylcarbodiimide), etc. Examples of alicyclic carbodiimide compounds include dicyclohexylcarbodiimide, poly(diisopropylcarbodiimide), etc.

[0070] Examples of aromatic carbodiimide compounds include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, di-2,6-ditert-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N-(2,6-diisopropyl-4-phenoxyphenyl)-N-tert-butylcarbodiimide, N,N-bis[3-isocyanato-2,4,6-tris(1-methylethyl)phenyl]- amino]carbodiimide, N-cyclohexyl-N-(4-(dimethylamino)naphthyl)carbodiimide, di-o-tolylcarbodiimide, di-p-tolylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide Mono- or dicarbodiimide compounds such as diimide, di-2,4,6-trimethylphenylcarbodiimide, di-2,4,6-triisopropylphenylcarbodiimide, di-2,4,6-triisobutylphenylcarbodiimide, p-phenylene-bis-di-o-triylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorophenylcarbodiimide, and ethylene-bis-diphenylcarbodiimide, as well as poly(4,4'-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide). Two or more of the above carbodiimide compounds can also be used in combination.

[0071] Among these, di-2,6-dimethylphenylcarbodiimide, poly(4,4'-diphenylmethanecarbodiimide), poly(phenylenecarbodiimide) and poly(triisopropylphenylenecarbodiimide) are particularly suitable.

[0072] It is preferable to use a carbodiimide compound having a number average molecular weight of 2000 or more. The amount of the carbodiimide compound in the composition is preferably such that the amount of the carbodiimide functional group is 5 to 40 equivalents when the amount of the terminal carboxyl group in the polyester-based thermoplastic resin A is taken as 1 equivalent.

[0073] A more preferable blend amount is when the amount of the terminal carboxyl group in the polyester-based thermoplastic resin A is 1 equivalent, and the amount of the carbodiimide functional group is 6 to 35 equivalents, and most preferably 10 to 30 equivalents.

[0074] The amount obtained by subtracting the amount of terminal carboxyl groups in polyester thermoplastic resin A from the amount of functional groups in the carbodiimide compound is 30 meq / kg or more of PBT, preferably 50 meq / kg or more of PBT, and even more preferably 70 meq / kg or more of polyester thermoplastic resin A. Note that this value is calculated from the amount of each functional group based on 1 kg of polyester thermoplastic resin A.

[0075] The amount of carbodiimide functional groups means the amount of carbodiimide functional groups in the carbodiimide compound in the resin composition, and the carbodiimide equivalent means the amount of carbodiimide functional groups in the carbodiimide compound.

[0076] Examples of epoxy compounds include alicyclic compounds such as vinylcyclohexene dioxide, glycidyl ester compounds such as persatic acid glycidyl ester, glycidyl ether compounds (hydroquinone diglycidyl ether, biphenol diglycidyl ether, bisphenol-A diglycidyl ether, etc.), glycidylamine compounds, epoxy group-containing vinyl copolymers (e.g., epoxidized polybutadiene, epoxidized diene monomer-styrene copolymer, etc.), triglycidyl isocyanurate, and epoxy-modified (poly)organosiloxanes.

[0077] Examples of the oxazoline compound include bisoxazolines such as 2,2'-bis(2-oxazoline), 1,3-phenylene-bis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), and 2,2'-p-phenylenebis(2-oxazoline). Further examples include oxazoline group-containing polymers such as oxazoline group-containing polystyrene, oxazoline group-containing acrylic polymers, and oxazoline group-containing styrene-acrylic polymers.

[0078] The epoxy compounds, carbodiimide compounds and oxazoline compounds may be used alone or in any combination of two or more in any ratio.

[0079] <Other ingredients> In the present invention, in addition to the above-mentioned components, known additives generally added to thermoplastic resins and thermosetting resins, namely, burr inhibitors, release agents, lubricants, plasticizers, flame retardants, colorants such as dyes and pigments, crystallization accelerators, crystal nucleating agents, various antioxidants, heat stabilizers, weather resistance stabilizers, corrosion inhibitors, etc. may also be blended within the scope of not impairing the effects of the present invention.

[0080] <Molded products> The molded article of the present invention is obtained by molding the resin composition for molded articles described above. The method for producing the molded article of the present invention is not particularly limited, and any known method can be used. For example, the molded article can be produced by feeding the resin composition described above into an extruder, melt-kneading it, and pelletizing it, and then feeding the pellets into an injection molding machine equipped with a predetermined mold and injection molding it. In the present invention, the hydrolysis resistance of the molded article can be improved. [Example]

[0081] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0082] <Material> The following materials were used to prepare evaluation samples, the amounts of which are shown in Tables 1 and 2. A1 Polybutylene terephthalate resin (PBT, intrinsic viscosity 0.69 dL / g, carboxylic acid terminal concentration 23 meq / k): manufactured by Polyplastics Co., Ltd. B1 Mica: Micalet 21PU manufactured by Yamaguchi Mica Kogyosho C1 Ethylene-glycidyl methacrylate copolymer: Sumitomo Chemical Co., Ltd. Bondfast 7L B 1MC11 After blending B1:C1 at 10:10 (parts by mass), the mixture was melt-kneaded and made into a masterbatch. BN1 Glass fiber: Nippon Electric Glass T187 (diameter 13 μm, length 3.0 mm) P Antioxidant: BASF Japan Irganox 1010 Q Lubricant: Sanwax 161-P manufactured by Sanyo Chemical Industries, Ltd.

[0083] <Production of Resin Composition> The master batch was prepared by melt-kneading B and C in the amounts shown in Table 1 at a cylinder temperature of 190°C, followed by pelletizing. In Example 1, Resin A1, pelletized masterbatch, and other ingredients such as Antioxidant P and Lubricant Q were added from a hopper, and Glass Fiber BN1 was added from a side feed. The mixture was mixed at a cylinder temperature of 260°C and then injection molded to produce an ISO multipurpose test piece Type-1A according to ISO3167. By the above coating confirmation method, it was confirmed that the inorganic filler B1 was coated with the olefin-based elastomer C1.

[0084] In Comparative Example 1, resin A1, olefin-based elastomer C1, inorganic filler B1, and other components such as antioxidant P and lubricant Q were charged from a hopper, and glass fiber BN1 was charged from a side feed. The mixture was mixed at a cylinder temperature of 260°C and then injection-molded to produce an ISO multipurpose test piece Type-1A according to ISO3167.

[0085] In Comparative Example 2, resin A1, inorganic filler B1, and other components such as antioxidant P and lubricant Q were added from a hopper, and olefin-based elastomer C1 and glass fiber BN1 were added from a side feed. The mixture was mixed at a cylinder temperature of 260°C and then injection-molded to produce an ISO multipurpose test piece Type-1A according to ISO3167.

[0086] <Evaluation> <Hydrolysis resistance evaluation> An ISO multipurpose test piece Type-1A conforming to ISO3167 was held in a pressure cooker tester at 121°C and 100% RH for 25 and 50 hours, and before and after, the tensile strength and tensile strain at break were measured using an Orientec Tensilon RTC-1325A universal testing machine conforming to ISO527-1 and 2. The retention rates were calculated using the following formula: Retention rate (unit: %) = (value after retention / value before retention) x 100 Unless otherwise specified, measurements were carried out in an atmosphere of 23°C and 50% RH.

[0087] <Evaluation results>

[0088] [Table 1]

[0089] [Table 2] [Table 3]

[0090] As shown in Tables 2 and 3, the present invention provides a molded article that is excellent in hydrolysis resistance while maintaining mechanical properties. Furthermore, it has been possible to provide a method for producing the molded article and a method for improving the hydrolysis resistance of the molded article. [Explanation of symbols]

[0091] A Thermoplastic resin B. Olefin elastomer (EGMA) BN: Inorganic filler (glass fiber) without surface coating C. Inorganic filler (mica) X CO Feed Y Side Feed 1 Hopper 2 motors 3 screws 4 cylinders 5 Strand Bus 6 cutter Pelet

Claims

1. A molded article made of a polyester resin composition, the polyester-based resin composition comprises a polyester-based thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester-based thermoplastic resin A; the polyester-based thermoplastic resin A has a carboxylic acid terminal concentration of 0.5 to 30 meq / kg; the polyester-based thermoplastic resin A is a polybutylene terephthalate resin, The inorganic filler B includes a plate-like filler and a fibrous filler, the plate-like filler is mica, the thermoplastic resin C is an ethylene-glycidyl methacrylate copolymer, A molded article in which the plate-like filler is coated with the thermoplastic resin C.

2. 2. The molded article according to claim 1, wherein the intrinsic viscosity of the polyester-based thermoplastic resin A is 0.6 dL / g or more.

3. 3. The molded article according to claim 1, wherein the polyester-based resin composition further comprises a compound (D) for improving water resistance, which is reactive with a carboxylic acid terminal group of the polyester-based thermoplastic resin (A).

4. A method for producing a molded article having improved hydrolysis resistance of a polyester resin composition, wherein the polyester resin composition comprises a polyester thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester thermoplastic resin A; the polyester-based thermoplastic resin A has a carboxylic acid terminal concentration of 0.5 to 30 meq / kg; the polyester-based thermoplastic resin A is a polybutylene terephthalate resin, The inorganic filler B includes a plate-like filler and a fibrous filler, the plate-like filler is mica, the thermoplastic resin C is an ethylene-glycidyl methacrylate copolymer, A method for producing a molded product with improved hydrolysis resistance, in which the plate-like filler and the thermoplastic resin C are melt-kneaded in advance, so that the plate-like filler is coated with the thermoplastic resin C, and then the plate-like filler is melt-kneaded with the polyester-based thermoplastic resin A.

5. A method for improving the hydrolysis resistance of a polyester resin composition, comprising: the polyester-based resin composition comprises a polyester-based thermoplastic resin A having an intrinsic viscosity of 1.2 dL / g or less, an inorganic filler B, and a thermoplastic resin C other than the polyester-based thermoplastic resin A; the polyester-based thermoplastic resin A has a carboxylic acid terminal concentration of 0.5 to 30 meq / kg; the polyester-based thermoplastic resin A is a polybutylene terephthalate resin, The inorganic filler B includes a plate-like filler and a fibrous filler, the plate-like filler is mica, the thermoplastic resin C is an ethylene-glycidyl methacrylate copolymer, A method for improving hydrolysis resistance, comprising melt-kneading the plate-like filler and the thermoplastic resin C in advance to coat the plate-like filler with the thermoplastic resin C, and then melt-kneading the plate-like filler with the polyester-based thermoplastic resin A.

Images