JP7513481B2 - Method for improving alkaline solution resistance of crystalline thermoplastic resin - Google Patents

Description

The present invention relates to a method for improving the alkaline solution resistance of a crystalline thermoplastic resin.

Thermoplastic resin molded products obtained by molding thermoplastic resins are nowadays used in a wide range of applications due to their formability and processability. Thermoplastic resin molded products used in environments in contact with alkaline solutions such as detergents, bleaches, and snow-melting agents are required to have excellent long-term durability against alkaline solutions in order to prevent deterioration of quality over time due to reaction with alkaline solutions. In particular, thermoplastic resin molded products used in a state in which excessive strain is applied due to screw tightening, metal press-in, crimping, etc., and thermoplastic resin molded products having parts where stress cracks are likely to occur, such as thin-walled parts and/or weld parts which are the interface between molten resin flows during molding, are more likely to cause cracks and the like in the above parts when used in environments in contact with alkaline solutions, so alkaline solution resistance is more required, and crystalline thermoplastic resins, which have better chemical resistance than amorphous thermoplastic resins, are generally used.
As a technique for further improving the resistance of this crystalline thermoplastic resin to alkaline solutions, there is a technique of blending a silicone-based compound and/or a fluorine-based compound with the crystalline thermoplastic resin (for example, Patent Document 1). However, when a molded product of a crystalline thermoplastic resin containing a silicone-based compound is used for, for example, the contact parts of electric and electronic components, silicon dioxide may be formed on the surface due to heat, sparks, etc., which may cause poor contact.
On the other hand, plasticizers, release agents, and the like are sometimes added to crystalline thermoplastic resins in consideration of processability and the like (for example, Patent Document 2).

International Publication No. WO 00/78867 International Publication No. 2011/058992

The first object of the present invention is to provide a method for improving the alkaline solution resistance of a crystalline thermoplastic resin. The second object of the present invention is to provide the use of an aromatic polycarboxylic acid ester and a dimensional accuracy improver for improving the alkaline solution resistance of a crystalline thermoplastic resin. The third object of the present invention is to provide an agent for improving the alkaline solution resistance of a crystalline thermoplastic resin.

The present inventors conducted extensive research into methods for improving the alkaline solution resistance of crystalline thermoplastic resins without using silicone-based compounds, and as a result, surprisingly discovered that the alkaline solution resistance of crystalline thermoplastic resins can be improved by blending aromatic polycarboxylic acid esters, which are commonly used as additives for crystalline thermoplastic resins.
The inventors conducted further research and discovered that by blending a dimensional accuracy improving agent containing at least an amorphous alloy resin in addition to an aromatic polycarboxylic acid ester, it is possible to suppress bleeding out of the aromatic polycarboxylic acid ester when used in a high temperature environment, etc., and to maintain the alkaline solution resistance of the crystalline thermoplastic resin for the long term.
The present invention has the following embodiments.
[1] A method for improving the alkaline solution resistance of (A) crystalline thermoplastic resin by blending 100 parts by mass of (A) crystalline thermoplastic resin containing at least one selected from polyacetal resin, polyamide resin, and polybutylene terephthalate resin with 1 to 15 parts by mass of (B) aromatic polycarboxylic acid ester, and 5 to 250 parts by mass of (C) dimensional accuracy improving agent containing (C-1) 5 to 100 parts by mass of amorphous alloy resin for improving dimensional accuracy and (C-2) 0 to 150 parts by mass of filler for improving dimensional accuracy in total of (C-1) and (C-2).
[2] (B) an aromatic polyvalent carboxylic acid ester represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The method according to [1], wherein the compound is represented by the formula:
[3] (C-1) The amorphous alloy resin for improving dimensional accuracy includes at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer. The method according to [1] or [2].
[4] (A) Use of an aromatic polycarboxylic acid ester (B) and a dimensional accuracy improver (C) for improving the alkaline solution resistance of a crystalline thermoplastic resin, wherein the crystalline thermoplastic resin (A) comprises at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin, the dimensional accuracy improver (C) comprises an amorphous alloy resin for improving dimensional accuracy (C-1) and a filler for improving dimensional accuracy (C-2), and the amount of the aromatic polycarboxylic acid ester (B) used relative to 100 parts by mass of the crystalline thermoplastic resin (A) is 1 to 15 parts by mass, and the amount of the dimensional accuracy improver (C) used relative to 100 parts by mass of the crystalline thermoplastic resin (A) is 5 to 250 parts by mass, which is a total amount of 5 to 100 parts by mass of (C-1) and 0 to 150 parts by mass of (C-2).
[5] (B) an aromatic polyvalent carboxylic acid ester represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The use according to [4], wherein the compound is represented by the formula:
[6] (C-1) The use according to [4] or [5], wherein the amorphous alloy resin for improving dimensional accuracy includes at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer.
[7] (A) An alkali solution resistance improver for a crystalline thermoplastic resin, comprising (B) an aromatic polycarboxylic acid ester and (C) a dimensional accuracy improver, wherein the (A) crystalline thermoplastic resin comprises at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin, and the (C) dimensional accuracy improver comprises (C-1) an amorphous alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the (B) aromatic polycarboxylic acid ester is used in an amount of 1 to 15 parts by mass, and the (C) dimensional accuracy improver is used in an amount of 5 to 250 parts by mass in total, with respect to 100 parts by mass of the (A) crystalline thermoplastic resin, of 5 to 100 parts by mass of (C-1) and 0 to 150 parts by mass of (C-2). The alkali solution resistance improver.
[8] (B) an aromatic polyvalent carboxylic acid ester represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The agent for improving alkaline solution resistance according to [7], which is a compound represented by the following formula:
[9] (C-1) The amorphous alloy resin for improving dimensional accuracy includes at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer. The alkaline solution resistance improver according to [7] or [8].
[10] The alkaline solution resistance improver according to any one of [7] to [9], wherein the dimensional accuracy improver (C) does not contain a silicone-based compound, or the content of the silicone-based compound in the dimensional accuracy improver (C) is 5 mass% or less.

According to the present invention, a method for improving the alkaline solution resistance of a crystalline thermoplastic resin can be provided. According to the present invention, the use of an aromatic polycarboxylic acid ester and a dimensional accuracy improver for improving the alkaline solution resistance of a crystalline thermoplastic resin can be provided. According to the present invention, an alkaline solution resistance improver for a crystalline thermoplastic resin can be provided.

One embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiment, and can be implemented with appropriate modifications within the scope that does not impair the effects of the present invention. When a specific description given for one embodiment also applies to other embodiments, that description is omitted in the other embodiments.

[Method for improving alkaline solution resistance]
The method for improving alkaline solution resistance according to this embodiment is a method for improving the alkaline solution resistance of a crystalline thermoplastic resin (A) by blending a crystalline thermoplastic resin (A) with an aromatic polycarboxylic acid ester (B) and a dimensional accuracy improving agent (C) consisting of an amorphous alloy resin (C-1) for improving dimensional accuracy and a filler (C-2) for improving dimensional accuracy.
"Alkaline solution resistance" refers to the property of being less susceptible to deterioration in quality even when in contact with an alkaline solution for a long period of time. In this specification, a test piece is said to have excellent alkaline solution resistance if no cracks occur after being immersed in an aqueous sodium hydroxide solution at 23°C for 50 hours or more.

((A) Crystalline Thermoplastic Resin)
Examples of the crystalline thermoplastic resin (A) include polyacetal (POM) resin, polyamide (PA) resin, and polybutylene terephthalate (PBT) resin, and one or more crystalline thermoplastic resins selected from these can be used. The crystalline thermoplastic resin (A) may contain a resin component other than the polyacetal (POM) resin, polyamide (PA) resin, and polybutylene terephthalate (PBT) resin, but the content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less. Particularly preferably 0.1% by mass or less.

((B) Aromatic polycarboxylic acid ester)
The aromatic polycarboxylic acid ester (B) may be an aromatic compound having two or more ester groups (such as an alkoxycarboxyl group, a cycloalkyloxycarbonyl group, or an aralkyloxycarbonyl group) on an aromatic ring, and examples thereof include compounds represented by the following formula I.

φ-(COOR)n...I
In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R of each -COOR group may be the same or different. φ may have hydrogen atoms other than the hydrogen atoms substituted with -COOR substituted with other substituents or may not be substituted. For example, φ may have a configuration in which one or more of the hydrogen atoms other than the hydrogen atoms substituted with -COOR are substituted with -OH and/or -NH _2. (A) In terms of compatibility with the crystalline thermoplastic resin, n is preferably 3 or more (for example, 3 to 6 or 3 to 4). These (B) aromatic polyvalent carboxylic acid esters can be used alone or in combination of two or more.

Examples of the _C6-12 arene ring include a benzene ring, a naphthalene ring, etc. Examples of the polycarboxylic acid of the aromatic polycarboxylic acid ester component include aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, and anhydrides thereof), aromatic tricarboxylic acids (trimellitic acid and anhydrides thereof), and aromatic tetracarboxylic acids (pyromellitic acid and anhydrides thereof).

Examples of the alkyl group constituting the alkyl ester (-COOR) include linear or branched C1-20 alkyl groups such as butyl, t-butyl, pentyl, hexyl, octyl, 2-ethylhexyl, isononyl, decyl _, isodecyl, triisodecyl, etc. Preferred alkyl groups are linear or branched _C3-16 alkyl groups, particularly linear or branched _C4-14 alkyl groups.
Examples of the cycloalkyl group constituting the cycloalkyl ester group include a C _5-10 cycloalkyl group such as a cyclohexyl group.
Examples of the aralkyl group constituting the aralkyl ester group include a C _6-12 aryl-C _1-4 alkyl group such as a benzyl group.

Representative examples of the aromatic polycarboxylic acid ester (B) include trimellitic acid tri C _4-20 alkyl esters (tributyl trimellitate, trioctyl trimellitate, tri(2-ethylhexyl) trimellitate, triisodecyl trimellitate, etc.), trimellitic acid tri C _5-10 cycloalkyl esters (tricyclohexyl trimellitate, etc.), trimellitic acid triaralkyls (tribenzyl trimellitate, etc.), trimellitic acid dialkyl monoaralkyls (di(2-ethylhexyl)monobenzyl trimellitate), pyromellitic acid tetra C _4-20 alkyl esters (tetrabutyl pyromellitate, tetraoctyl pyromellitate, tetra-2-ethylhexyl pyromellitate, tetraisodecyl pyromellitate, etc.), pyromellitic acid tetraaralkyls (tetrabenzyl pyromellitate, etc.), pyromellitic acid dialkyl diaralkyls (di(2-ethylhexyl)dibenzyl pyromellitate, etc.). The carboxylate may be a mixed ester having different ester groups (such as an alkoxycarboxyl group, a cycloalkyloxycarbonyl group, or an aralkyloxycarbonyl group).

The blending amount of (B) aromatic polycarboxylic acid ester is 1 to 15 parts by mass, preferably 2 to 12 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of (A) crystalline thermoplastic resin. By making the blending amount of (B) aromatic polycarboxylic acid ester 1 part by mass or more per 100 parts by mass of (A) crystalline thermoplastic resin, the resistance to alkaline solutions can be further improved. By making the blending amount of (B) aromatic polycarboxylic acid ester 15 parts by mass or less per 100 parts by mass of crystalline thermoplastic resin, the long-term durability against alkaline solutions can be further exhibited, and the occurrence of defects such as the bleeding of (B) aromatic polycarboxylic acid ester onto the surface of a molded article can be suppressed. In one embodiment, the blending amount of (B) aromatic polycarboxylic acid ester is 4 to 7 parts by mass per 100 parts by mass of (A) crystalline thermoplastic resin.

((C) Dimensional Accuracy Improving Agent)
In this embodiment, since the crystalline thermoplastic resin (A) is used, deformation such as warping may occur in the molded product due to molding shrinkage accompanying crystallization during the cooling and solidifying process during molding, or post-shrinkage in the environment in which the molded product is used. Such deformation may cause distortion (stress) in the molded product and promote a decrease in alkaline solution resistance, so suppressing deformation of the molded product is also important in improving alkaline solution resistance. Therefore, in the method according to this embodiment, in order to suppress deformation of the molded product and improve alkaline solution resistance, (C) a dimensional accuracy improving agent consisting of (C-1) an amorphous alloy resin for improving dimensional accuracy and/or (C-2) a filler for improving dimensional accuracy is added.

As the (C-1) amorphous alloy resin for improving dimensional accuracy, a resin that not only has a small shrinkage rate and/or linear expansion coefficient during molding or heat treatment, but also has a processing temperature close to that of each resin (polyacetal resin, polyamide resin, polybutylene terephthalate resin) used as the (A) crystalline thermoplastic resin and has good compatibility can be preferably used. Examples of such (C-1) alloy resin for improving dimensional accuracy include polycarbonate resin, polyethylene terephthalate resin, styrene-based resin (polystyrene resin, acrylonitrile-styrene copolymer, etc.), urethane-based resin, polyarylate resin, polyphenylene ether resin, elastomer (olefin-based elastomer, diene-based elastomer, core-shell-based elastomer, polyester-based elastomer, silicone-based elastomer, etc.), and combinations thereof.
Among them, when one or more selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer are used, the effect of suppressing the bleeding out of the aromatic polycarboxylic acid ester (B) is also obtained, which is particularly preferable. In order to improve the affinity between the amorphous alloy resin for improving dimensional accuracy (C-1) and the crystalline thermoplastic resin (A), a known compatibilizer may be used in combination.

The polycarbonate resin means a polymer having a carbonate bond in the main chain, and is usually obtained by polycondensation of a dihydroxy compound and phosgene, or by transesterification of a dihydroxy compound and a carbonate ester. The polycarbonate may be any of aliphatic, alicyclic, and aromatic polycarbonates. Preferred polycarbonates include aromatic polycarbonates, particularly bisphenol-type polycarbonates such as bisphenol A-type polycarbonate.
The polyethylene terephthalate resin is a polyethylene terephthalate-based resin obtained by a polycondensation reaction between a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof and a glycol component containing at least an alkylene glycol having two carbon atoms (ethylene glycol) or an ester-forming derivative thereof, and is not limited to a homo-PET resin, but may be a copolymer (copolymerized PET) resin containing 60 mol % or more (particularly about 75 to 95 mol %) of ethylene terephthalate units.
The styrene-based resin may be produced by any of bulk polymerization, solution polymerization, and suspension polymerization methods. From the viewpoint of improving dimensional accuracy, it is more preferable to use a styrene-based resin produced by bulk polymerization.

Examples of the polyphenylene ether resin include modified polyphenylene ether in addition to polyphenylene ether. Examples of the cyclic olefin resin include cyclic olefin polymer (COP) and cyclic olefin copolymer (COC).
Examples of olefin-based elastomers include ethylene-propylene copolymers (EP copolymers), ethylene-butene copolymers, ethylene-octene copolymers, ethylene-propylene-diene copolymers (EPD copolymers), ethylene-propylene-butene copolymers, ethylene-vinyl acetate copolymers, styrene-ethylene-butadiene-styrene copolymers, copolymers containing at least one unit selected from EP copolymers and EPD copolymers, and copolymers of olefins and (meth)acrylic monomers (ethylene-ethyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, etc.). Preferred olefin-based elastomers include EP copolymers, EPD copolymers, and copolymers of olefins and (meth)acrylic monomers, with ethylene-ethyl acrylate being particularly preferred. These olefin-based elastomers can be used alone or in combination of two or more.

Examples of the diene elastomer include butadiene rubber, isoprene rubber, acrylonitrile-butadiene-styrene copolymer, styrene-butadiene copolymer, styrene-butadiene-styrene copolymer, and styrene-isoprene-styrene copolymer.
The core-shell elastomer is a polymer in which the core layer is composed of a rubber component (soft component) and the shell layer is composed of a hard component, and the rubber component of the core layer is an acrylic rubber, etc. The rubber component used in the core layer preferably has a glass transition temperature (Tg) of less than 0° C. (e.g., −10° C. or less), more preferably −20° C. or less (e.g., −180° C. or more and −25° C. or less), and particularly preferably −30° C. or less (e.g., −150° C. or more and −40° C. or less).

When using an acrylic rubber as the rubber component, a polymer obtained by polymerizing an acrylic monomer such as an alkyl acrylate as the main component is preferred. The alkyl acrylate used as the monomer for the acrylic rubber is preferably a C1 to C12 alkyl ester of acrylic acid such as butyl acrylate, and more preferably a C2 to C6 alkyl ester of acrylic acid.

The acrylic rubber may be a homopolymer or a copolymer of an acrylic monomer. When the acrylic rubber is a copolymer of an acrylic monomer, it may be a copolymer of acrylic monomers or a copolymer of an acrylic monomer and another unsaturated bond-containing monomer. When the acrylic rubber is a copolymer, it may be a copolymer of a crosslinkable monomer.

For the shell layer, vinyl polymers are preferably used. The vinyl polymers are obtained by polymerizing or copolymerizing at least one monomer selected from, for example, aromatic vinyl monomers, vinyl cyanide monomers, methacrylic acid ester monomers, and acrylic acid ester monomers. The core layer and shell layer of such a core-shell elastomer may be bonded by graft copolymerization. This graft copolymerization can be obtained by adding a graft crossing agent that reacts with the shell layer during polymerization of the core layer, if necessary, and then forming the shell layer after providing a reactive group to the core layer. When a silicone rubber is used as the graft crossing agent, an organosiloxane having a vinyl bond or an organosiloxane having a thiol is used, and preferably acryloxysiloxane, methacryloxysiloxane, or vinylsiloxane is used.

As polyester-based elastomers, either an ester-ester type in which both the hard segment and the soft segment have a polyester-based unit structure, or an ester-ether type in which the soft segment has a polyether-based unit structure can be preferably used, but the former is more preferable in terms of heat resistance, and the latter is more preferable in terms of dimensional accuracy.

The amount of the amorphous alloy resin for improving dimensional accuracy (C-1) added is 5 to 100 parts by mass, or may be 10 to 90 parts by mass or 15 to 80 parts by mass, relative to 100 parts by mass of the crystalline thermoplastic resin (A). In one embodiment, the amount of the amorphous alloy resin for improving dimensional accuracy (C-1) added is 12 to 45 parts by mass relative to 100 parts by mass of the crystalline thermoplastic resin (A).
However, since amorphous resins generally have inferior chemical resistance compared to crystalline resins, and adding a large amount of the amorphous resin may deteriorate the alkaline solution resistance of the composition, the content of the amorphous alloy resin for improving dimensional accuracy is preferably 40 mass% or less, more preferably 30 mass% or less, and even more preferably 20 mass% or less, relative to the entire resin composition obtained using the method according to this embodiment.

(C-2) As the filler for improving dimensional accuracy, any of organic fillers, inorganic fillers, metallic fillers, and combinations of these can be used. However, inorganic fillers and metallic fillers that have a small shrinkage rate and linear expansion coefficient in the processing temperature range and use temperature range of the resin molded product are preferred. For molded products used as insulating members combined with metal members, it is particularly preferred to use inorganic fillers in order to ensure insulation.

(C-2) The shape of the filler for improving dimensional accuracy can be any of fibrous fillers, plate-like fillers, spherical fillers, powdered fillers, curved fillers, irregular fillers, and combinations of these. However, in order to reduce warpage, it is preferable to use a filler with low anisotropy, so it is more preferable to use a plate-like filler, spherical filler, powdered filler, etc., especially a filler with an aspect ratio close to 1. On the other hand, when using a fibrous filler such as glass fiber, the effect of improving mechanical properties such as tensile strength is large, but due to the orientation of the fibrous filler, the anisotropy of the shrinkage rate that causes warpage tends to become large. Therefore, it is more preferable to use a fibrous filler with a relatively large cross-sectional aspect ratio, such as short fibers such as milled fibers and whiskers, or fibers with a flat cross-section such as a cocoon-shaped, oval, or elliptical cross-section (for example, the ratio of the major axis to the minor axis of the cross-section is 1.3 to 10).

Specific examples of plate-like fillers include plate-like talc, mica, glass flakes, metal pieces, and combinations thereof. Specific examples of spherical fillers include glass beads, glass balloons, spherical silica, and combinations thereof. Specific examples of powdered fillers include glass powder, talc powder, quartz powder, kaolin, clay, diatomaceous earth, wollastonite, silicon carbide, silicon nitride, metal powder, powders of inorganic acid metal salts (calcium carbonate, zinc borate, calcium borate, zinc stannate, calcium sulfate, barium sulfate, etc.), powders of metal oxides (magnesium oxide, iron oxide, titanium oxide, zinc oxide, alumina, etc.), powders of metal hydroxides (aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, alumina hydrate (boehmite), etc.), powders of metal sulfides (zinc sulfide, molybdenum sulfide, tungsten sulfide, etc.), and combinations thereof. From the viewpoint of metal corrosivity, it is preferable that the content of free inorganic acid contained in these (C-2) dimensional accuracy improving fillers is 0.5 mass% or less.

(C-2) The size of the filler for improving dimensional accuracy can be appropriately selected taking into consideration the balance between the warpage reduction effect and the mechanical properties and fluidity. For example, as talc, talc having a volume average particle size of 1 to 10 μm measured by a laser diffraction/scattering type particle size distribution analyzer in accordance with JIS Z8825, or compressed fine powder talc having a bulk density of 0.4 to 1.5 measured in accordance with JIS K5101 can be suitably used, and as mica, mica having a volume average particle size of 10 to 60 μm measured by a laser diffraction/scattering type particle size distribution analyzer in accordance with JIS Z8825 can be suitably used.

These (C-2) dimensional accuracy improving fillers may be surface treated (surface coated) with an inorganic compound and/or an organic compound. Examples of inorganic compounds used for surface treatment include inorganic oxides and hydroxides of aluminum, silicon, zirconium, cerium, etc., such as aluminum hydroxide, alumina, silica, zirconia, zirconium hydroxide, zirconia hydrate, cerium oxide, cerium oxide hydrate, and cerium hydroxide. These inorganic compounds may also be hydrates. Among these, aluminum hydroxide and silica are preferred, and when silica is used, silica hydrate represented by SiO2.nH2O is particularly preferred. Examples of organic compounds used for surface treatment include epoxy compounds and amine compounds, and more preferred compounds include epoxy compounds such as bisphenol A type epoxy and novolac type epoxy, and amine compounds such as monoethanolamine, diethanolamine, triethanolamine, and dichlorohexylamine.

When a porous material such as zeolite or mesoporous silica is used as the (C-2) dimensional accuracy improving filler, the (B) aromatic polycarboxylic acid ester may be adsorbed onto it. This can suppress the bleeding out of the (B) aromatic polycarboxylic acid ester from the molded product, but on the other hand, it can inhibit the dispersion of the (B) aromatic polycarboxylic acid ester throughout the resin molded product, which may reduce the effect of improving alkaline solution resistance. In such cases, the amount added can be adjusted appropriately while checking the balance between the warpage reduction effect, alkaline solution resistance, and bleeding out.

The amount of the filler for improving dimensional accuracy (C-2) added is 0 to 150 parts by mass, and may be 5 to 120 parts by mass or 10 to 100 parts by mass, relative to 100 parts by mass of the crystalline thermoplastic resin (A). The amount of the filler for improving dimensional accuracy (C-2) added can be appropriately selected in consideration of the balance between the warpage reduction effect and the mechanical properties and fluidity. In one embodiment, the amount of the filler for improving dimensional accuracy (C-2) added is 0 to 69 parts by mass relative to 100 parts by mass of the crystalline thermoplastic resin (A). In one embodiment, the amount of the filler for improving dimensional accuracy (C-2) added is 50 to 69 parts by mass relative to 100 parts by mass of the crystalline thermoplastic resin (A).

The amount of the dimensional accuracy improving agent (C) consisting of the above-mentioned (C-1) alloy resin for improving dimensional accuracy and/or (C-2) filler for improving dimensional accuracy is 5 to 250 parts by mass, or may be 10 to 200 parts by mass or 15 to 150 parts by mass, as the total of the (C-1) alloy resin for improving dimensional accuracy and the (C-2) filler for improving dimensional accuracy, per 100 parts by mass of the (A) crystalline thermoplastic resin. In one embodiment, the amount of the (C) dimensional accuracy improving agent is 45 to 106 parts by mass in total per 100 parts by mass of the (A) crystalline thermoplastic resin.

(Other compounding agents)
In the method for improving alkaline solution resistance according to the present embodiment, additives such as antioxidants, weathering stabilizers, molecular weight regulators, flowability improvers, hydrolysis resistance improvers, ultraviolet absorbers, infrared absorbers, antistatic agents, colorants such as dyes and pigments, crystallization accelerators, crystal nucleating agents, flame retardants, flame retardant assistants, organic fillers, and colorants can be further blended into the crystalline thermoplastic resin (A) as necessary, within a range that does not impair the effects of the present invention. In addition, since the aromatic polycarboxylic acid ester (B) described above can also act as a plasticizer, it is usually not necessary to add a plasticizer, but other plasticizers such as aliphatic carboxylic acid esters can be contained as necessary. In this case, the content of the plasticizer can be 0.01 to 10 parts by mass relative to 100 parts by mass of the crystalline thermoplastic resin (A).

According to the method for improving resistance to alkaline solutions according to this embodiment, the resistance to alkaline solutions of the crystalline thermoplastic resin (A) can be improved without using a silicone-based compound. Therefore, when the resin composition obtained using the method according to this embodiment is used for electrical and electronic components, poor contact caused by the generation of a silicon dioxide layer derived from the silicone-based compound can be suppressed. From this point of view, the amount of the silicone-based compound is preferably 1 mass% or less, more preferably 0.5 mass% or less, and even more preferably 0.1 mass% or less, based on the total amount of the resin composition obtained using the method according to this embodiment. It is also possible to configure the composition without adding a silicone-based compound. Examples of silicone-based compounds include silicone resins such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane, which are known as silicone oils; modified silicones obtained by reacting silicone resins with modifying resins such as alkyd resins, polyester resins, acrylic resins, and epoxy resins.

(Mixing Method)
The method of blending (A) crystalline thermoplastic resin with (B) aromatic polycarboxylic acid ester and (C) dimensional accuracy improving agent, as well as compounding agents added as necessary, is not particularly limited, and can be easily prepared using equipment and methods generally used for conventional resin composition preparation methods and molding methods. For example, 1) a method of mixing resin components and other components, kneading and extruding them with a single-screw or twin-screw extruder to prepare pellets, and then molding them; 2) a method of preparing pellets with different compositions, mixing a predetermined amount of the pellets, subjecting them to molding, and obtaining a molded product with the desired composition after molding; 3) a method of directly charging one or more of each component into a molding machine, etc., can be used. In addition, a method of making a part of the resin components into fine powder, mixing it with other components, and adding it is a preferred method for achieving uniform blending of these components.

When kneading and pelletizing the mixture using an extruder, the resin temperature (processing temperature) in the extruder may be set appropriately depending on the type of crystalline thermoplastic resin (A) used. From the viewpoint of preventing deterioration of mechanical properties due to thermal decomposition and from the viewpoint of sufficiently reacting the crystalline thermoplastic resin (A) with the aromatic polycarboxylic acid ester (B) to exhibit resistance to alkaline solutions, the extruder cylinder temperature can be set to preferably 150 to 320°C, more preferably 180 to 280°C. When a polyacetal resin is used as the crystalline thermoplastic resin (A), the cylinder temperature is preferably 170 to 220°C (particularly 180 to 210°C), and when a polyamide resin and/or a polybutylene terephthalate resin is used, the cylinder temperature is preferably 240 to 300°C (particularly 250 to 280°C).

The above method is preferably a method for preventing cracks from occurring after a test piece made of a crystalline thermoplastic resin composition obtained using the method according to this embodiment, which has a size of 80 mm x 10 mm x 1 mm thickness and a weld approximately in the center of the longitudinal direction, is immersed in a sodium hydroxide solution at 23°C for 50 hours or more in a state where the test piece is bent so that a bending strain of 1.0% is constantly applied to the weld, more preferably a method for preventing cracks from occurring after immersion for 70 hours or more, even more preferably a method for preventing cracks from occurring after immersion for 100 hours or more, and particularly preferably a method for preventing cracks from occurring after immersion for 200 hours or more.

(Resin molded products)
The crystalline thermoplastic resin (A) blended with the aromatic polycarboxylic acid ester (B) and the dimensional accuracy improving agent (C) by the above method has excellent resistance to alkaline solutions, so that the molded product can be widely used in applications requiring resistance to alkaline solutions. For example, it can be suitably used as a part that comes into contact with alkaline solutions such as detergents and snow melting agents, among automobile parts, electric and electronic parts, etc. The method for obtaining a resin molded product is not particularly limited, and a known method can be adopted. For example, the resin blended with the aromatic polycarboxylic acid ester by the above method is fed into an extruder, melt-kneaded and pelletized, and the pellets are fed into an injection molding machine equipped with a predetermined mold and injection molded to produce the product.

[Use of (B) aromatic polycarboxylic acid ester and (C) dimensional accuracy improving agent]
The use of the aromatic polycarboxylic acid ester (B) and the dimensional accuracy improver (C) according to this embodiment is the use of the aromatic polycarboxylic acid ester (B) and the dimensional accuracy improver (C) for improving the resistance of the crystalline thermoplastic resin (A) to an alkaline solution. The above use is preferably such that the test piece is immersed in a sodium hydroxide solution at 23° C. for 50 hours or more in a state where the test piece is bent so that a bending strain of 1.0% is always applied to the weld portion, and is not cracked after immersion for 70 hours or more, more preferably such that the test piece is not cracked after immersion for 100 hours or more, and particularly preferably such that the test piece is not cracked after immersion for 200 hours or more. The types of the crystalline thermoplastic resin (A), the aromatic polycarboxylic acid ester (B), and the dimensional accuracy improver (C) are as described above, and therefore will not be described here. The amounts of the aromatic polycarboxylic acid ester (B) and the dimensional accuracy improver (C) used are the same as the amounts of the aromatic polycarboxylic acid ester (B) and the dimensional accuracy improver (C) used.

[Alkaline solution resistance improver]
The alkaline solution resistance improver according to this embodiment is intended to be blended with (A) a crystalline thermoplastic resin and contains (B) an aromatic polycarboxylic acid ester and (C) a dimensional accuracy improver.

The total content of (B) aromatic polycarboxylic acid ester and (C) dimensional accuracy improver in the alkaline solution resistance improver is preferably 50% by mass or more, more preferably 70% by mass or more, and can be 80% by mass or more or 90% by mass or more, and can be composed of only aromatic polycarboxylic acid ester. The alkaline solution resistance improver may contain other compounding agents that may be compounded with the above-mentioned (A) crystalline thermoplastic resin. The compounding amount is not particularly limited, and can be, for example, less than 50% by mass in total, 30% by mass or less, 20% by mass or less, or 10% by mass or less.

The content of each component in the alkaline solution resistance improver is preferably within the following range so that it can be easily used in the above-mentioned blending amount relative to the crystalline thermoplastic resin (A).
The content of the aromatic polycarboxylic acid ester (B) in the alkaline solution resistance improver is preferably 0.1 to 50 mass %, more preferably 1 to 30 mass %, and even more preferably 3 to 15 mass %.
The content of the dimensional accuracy improver (C) in the alkaline solution resistance improver is preferably 50 to 99.9% by mass, more preferably 70 to 99% by mass, and even more preferably 85 to 97% by mass.
The content of the amorphous alloy resin for improving dimensional accuracy (C-1) in the dimensional accuracy improving agent (C) is preferably 3 to 100 mass%, more preferably 5 to 95 mass%, and even more preferably 10 to 90 mass%.
The content of the (C-2) dimensional accuracy improving filler in the (C) dimensional accuracy improving agent is preferably 0 to 97 mass %, more preferably 5 to 95 mass %, and even more preferably 10 to 90 mass %.

The alkaline solution resistance improver according to this embodiment can improve the alkaline solution resistance of the (A) crystalline thermoplastic resin without using a silicone-based compound, so it can be configured to contain no silicone-based compound or to have a silicone-based compound content of less than 5 mass%.

The alkaline solution resistance improver is preferably one that does not generate cracks after the test piece is immersed in a sodium hydroxide solution at 23°C for 50 hours or more while being bent so that a bending strain of 1.0% is constantly applied to the weld portion, more preferably one that does not generate cracks after immersion for 70 hours or more, even more preferably one that does not generate cracks after immersion for 100 hours or more, and particularly preferably one that does not generate cracks after immersion for 200 hours or more.

The types of (A) crystalline thermoplastic resin, (B) aromatic polycarboxylic acid ester, and (C) dimensional accuracy improver are as described above, so a detailed description will be omitted here. The amount of alkaline solution resistance improver used can be an amount that provides the amount of (B) aromatic polycarboxylic acid ester in the alkaline solution resistance improver relative to the amount of (A) crystalline thermoplastic resin described above.

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

In each of the Examples and Comparative Examples, (A) a crystalline thermoplastic resin, (B) an aromatic polycarboxylic acid ester, and (C) a dimensional accuracy improving agent shown in Table 1 were dry-blended in the amounts (parts by mass) shown in Table 1 together with compounding ingredients used as necessary, and melt-kneaded at a cylinder temperature of 260°C using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) having a 30 mmφ screw to obtain a pellet-shaped resin composition.
The details of each component used are as follows:

(1) (A) Crystalline Thermoplastic Resin PBT: Polybutylene terephthalate resin manufactured by Polyplastics Co., Ltd. (intrinsic viscosity: 0.77 dL/g, terminal carboxyl group amount: 28 meq/kg)
PA: Polyamide 6 "UBE Nylon 1015B" manufactured by Ube Industries, Ltd.
(2) (B) Aromatic polycarboxylic acid ester Pyromellitic acid ester: Pyromellitic acid mixed linear alkyl ester "ADEKA Cizer UL-100" manufactured by ADEKA CORPORATION
(Comparative component 1) Aromatic monocarboxylic acid ester: Polycaprolactone dibenzoate "PLACCEL BCL2" manufactured by Daicel Corporation
(Comparative component 2) Aliphatic polycarboxylic acid ester: Pentaerythritol distearate "Unistar H476" manufactured by NOF Corporation
(3) (C-1) Amorphous alloy resin for improving dimensional accuracy PC: Teijin Limited, polycarbonate resin "Panlite L-1225W"
PET: Teijin Limited, polyethylene terephthalate resin "TRN-8550FF"
AS: Acrylonitrile-styrene resin "80HF" manufactured by Ningbo LG Yongxing Chemical Co., Ltd.
PPE: Modified polyphenylene ether resin "Iupiace PX-100L" manufactured by Mitsubishi Engineering Plastics Corporation
EEA: Ethylene-ethyl acrylate copolymer "NUC-6570" manufactured by NUC Corporation
EO: ethylene-octene copolymer "ENGAGE 8440" manufactured by Dow Chemical Japan Co., Ltd.
EGMA-g-BAMMA: ethylene-glycidyl methacrylate-graft-(butyl acrylate-methyl methacrylate) copolymer "Modiper A4300" manufactured by NOF Corporation
Core-shell: glycidyl group-containing core-shell polymer "Paraloid EXL2314" manufactured by Dow Chemical Japan Co., Ltd.
PEs elastomer: Polyester elastomer "Pelprene S2001" manufactured by Toyobo Co., Ltd.
(4) (C-2) Filler for improving dimensional accuracy Circular cross-section glass fiber: "ECS03T-127" (average fiber diameter 13 μm, average fiber length 3 mm) manufactured by Nippon Electric Glass Co., Ltd.
Flat cross-section glass fiber: "CSG3PA830" manufactured by Nitto Boseki Co., Ltd. (oval cross section with long diameter 28 μm and short diameter 7 μm (long diameter ÷ short diameter ratio = 4), average fiber length 3 mm)
Glass flakes: Micro glass "Freca REFG-301" manufactured by Nippon Sheet Glass Co., Ltd.
Talc: "Crown Talc PP" manufactured by Matsumura Sangyo Co., Ltd.
(5) Other compounding agents Flame retardant: Polypentabromobenzyl acrylate (PBBPA) "FR-1025" manufactured by Bromochem Far East Co., Ltd.
Flame retardant assistant: Antimony trioxide "PATOX-M" manufactured by Nippon Seiko Co., Ltd.

<Evaluation>
(Alkaline solution resistance)
After drying the pellets of the resin composition at 140 ° C for 3 hours, the resin composition was injection molded at a cylinder temperature of 250 ° C, a mold temperature of 70 ° C, an injection time of 20 seconds, and a cooling time of 10 seconds using a mold for molding a test piece (a mold for molding a flat plate having a length of 80 mm, a width of 80 mm, and a thickness of 1 mm, in which a pin was installed at a position corresponding to the approximate center of one main surface of the flat plate, so that a weld was generated on one main surface of the flat plate when the resin was filled from a side gate having a width of 2 mm and a thickness of 1 mm provided at the center of one side of the flat plate). A flat plate molded product with a weld was produced by cutting the obtained flat plate molded product with a weld into a strip shape having a width of 10 mm and a length of 80 mm so that the weld was located at the approximate center in the longitudinal direction. The test piece was fixed to a jig in a bent state, and a bending strain of 1.0% was constantly applied to the weld part. In this state, the jig was immersed in a 10% sodium hydroxide solution and left to stand at an ambient temperature of 23°C. The test pieces were visually observed to see whether or not cracks had occurred 72 hours, 120 hours, and 240 hours after the start of immersion.
The evaluation was carried out using three test pieces for each of the pellets of the Examples and Comparative Examples, and was based on the following criteria. The results are shown in Tables 1 and 2.
◎ (Excellent): No cracks occurred in any of the three test pieces. 〇 (Good): Only one crack occurred in one of the three test pieces. △ (Fair): Cracks occurred in two of the three test pieces. × (Unacceptable): Cracks occurred in all three test pieces.

(Low warpage)
After drying the pellets of the resin composition at 140 ° C for 3 hours, a square flat plate-shaped test piece having a length of 120 mm, a width of 120 mm, and a thickness of 2 mm was molded at a cylinder temperature of 260 ° C, a mold temperature of 60 ° C, an injection pressure of 60 MPa, an injection speed of 17 mm / s, an injection time of 10 seconds, and a cooling time of 10 seconds, and the flatness was measured. The flatness was measured by placing the side of the test piece without the ejection pin marks on a table, and measuring nine points of 10 mm x 10 mm, 10 mm x 60 mm, 10 mm x 110 mm, 60 mm x 10 mm, 60 mm x 60 mm, 60 mm x 110 mm, 110 mm x 10 mm, 110 mm x 60 mm, and 110 mm x 110 mm with a Mitutoyo CNC image measuring machine, and was obtained from the difference in height between the highest point and the lowest point. The flatness was evaluated as follows: ◯ for flatness of 5 mm or less, △ for flatness of 5 to 10 mm, and × for flatness of 10 mm or more. The results are shown in Table 1.

(Bleeding resistance)
Using pellets of the resin composition, evaluation test pieces (flat plates of 8 cm x 8 cm x 3 mm thickness) were prepared under the same molding conditions as the molded articles used in the above alkaline solution resistance test, and the molded articles were left in a gear oven manufactured by Toyo Seiki Seisakusho Co., Ltd. at 110°C for 20 hours, after which the state of bleeding on the surface of the molded articles was visually observed. Evaluation was based on the following criteria. The results are shown in Table 1.
◎ (Excellent): No bleeding 〇 (Good): Very slight bleeding △ (Fair): Some bleeding × (Poor): Significant bleeding

Claims (13)

100 parts by mass of a crystalline thermoplastic resin (A) containing at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin,
(B) 1 to 15 parts by mass of an aromatic polycarboxylic acid ester;
(C-1) 5 to 100 parts by mass of an amorphous alloy resin for improving dimensional accuracy and (C-2) 0 to 150 parts by mass of a filler for improving dimensional accuracy, (C) a dimensional accuracy improving agent, in which (C-1) and (C-2) are combined to form a total of 5 to 250 parts by mass;
(A) improving the resistance of a crystalline thermoplastic resin to an alkaline solution by blending (B) the aromatic polycarboxylic acid ester is represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The method according to claim 1, wherein the compound is represented by the formula: The method according to claim 1 or 2, wherein (C-1) the amorphous alloy resin for improving dimensional accuracy includes at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer. (A) A method for improving the alkaline solution resistance of a crystalline thermoplastic resin,
100 parts by mass of a crystalline thermoplastic resin (A) containing at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin,
(B) 1 to 15 parts by mass of an aromatic polycarboxylic acid ester;
(C-1) 5 to 100 parts by mass of an amorphous alloy resin for improving dimensional accuracy and (C-2) 0 to 150 parts by mass of a filler for improving dimensional accuracy, (C) a dimensional accuracy improving agent, in which (C-1) and (C-2) are combined to form a total of 5 to 250 parts by mass;
The method includes blending
(C-1) The amorphous alloy resin for improving dimensional accuracy is one or more selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, and polyphenylene ether resin;
Method. (A) Use of an aromatic polycarboxylic acid ester (B) and a dimensional accuracy improving agent (C) for improving the alkaline solution resistance of a crystalline thermoplastic resin,
(A) the crystalline thermoplastic resin includes at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin;
(C) the dimensional accuracy improving agent comprises (C-1) an amorphous alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the amounts of (B) aromatic polycarboxylic acid ester used per 100 parts by mass of (A) the crystalline thermoplastic resin are 1 to 15 parts by mass, and (C) the dimensional accuracy improving agent is 5 to 250 parts by mass in total, consisting of 5 to 100 parts by mass of (C-1) and 0 to 150 parts by mass of (C-2). (B) the aromatic polycarboxylic acid ester is represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The use according to claim 5, wherein the compound is represented by the formula: The use according to claim 5 or 6, wherein the amorphous alloy resin for improving dimensional accuracy (C-1) comprises at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene - based elastomer. (A) Use of an aromatic polycarboxylic acid ester (B) and a dimensional accuracy improving agent (C) for improving the alkaline solution resistance of a crystalline thermoplastic resin,
(A) the crystalline thermoplastic resin includes at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin;
(C) the dimensional accuracy improving agent contains (C-1) an amorphous alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy,
(C-1) The amorphous alloy resin for improving dimensional accuracy is made of one or more selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, and polyphenylene ether resin, and
The amount of (B) aromatic polycarboxylic acid ester used per 100 parts by mass of the crystalline thermoplastic resin (A) is 1 to 15 parts by mass, and the amount of (C) dimensional accuracy improving agent used is 5 to 250 parts by mass in total, consisting of 5 to 100 parts by mass of (C-1) and 0 to 150 parts by mass of (C-2). (A) an alkali solution resistance improver for a crystalline thermoplastic resin,
(B) an aromatic polycarboxylic acid ester and (C) a dimensional accuracy improving agent,
(A) the crystalline thermoplastic resin includes at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin;
The alkaline solution resistance improver includes (C) an amorphous alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the amount of the aromatic polycarboxylic acid ester (B) is 1 to 15 parts by mass, and the amount of the dimensional accuracy improver (C) is 5 to 100 parts by mass of (C-1) and 0 to 150 parts by mass of (C-2) per 100 parts by mass of the crystalline thermoplastic resin (A), resulting in a total amount of 5 to 250 parts by mass. (B) the aromatic polycarboxylic acid ester is represented by formula I:
φ-(COOR)n...I
(In formula I, φ represents a C _6-12 arene ring, R represents an alkyl group, a cycloalkyl group or an aralkyl group, n represents an integer of 2 or more, and R in each -COOR group may be the same or different.)
The alkaline solution resistance improver according to claim 9 , which is a compound represented by the following formula: The amorphous alloy resin for improving dimensional accuracy (C-1) is at least one selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, polyurethane resin, polyarylate resin, polyphenylene ether resin, olefin-based elastomer, and diene-based elastomer. The alkaline solution resistance improver according to claim 9 or 10 . The alkaline solution resistance improver according to any one of claims 9 to 11 , wherein the dimensional accuracy improver (C) does not contain a silicone-based compound, or the content of the silicone-based compound in the dimensional accuracy improver (C) is 5 mass% or less. (A) an alkali solution resistance improver for a crystalline thermoplastic resin,
(B) an aromatic polycarboxylic acid ester and (C) a dimensional accuracy improving agent,
(A) the crystalline thermoplastic resin includes at least one selected from a polyacetal resin, a polyamide resin, and a polybutylene terephthalate resin;
(C) the dimensional accuracy improving agent contains (C-1) an amorphous alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy,
(C-1) The amorphous alloy resin for improving dimensional accuracy is made of one or more selected from polycarbonate resin, polyethylene terephthalate resin, styrene-based resin, and polyphenylene ether resin, and
The alkaline solution resistance improver is used in an amount of 5 to 250 parts by mass in total, based on 100 parts by mass of the crystalline thermoplastic resin (A), including 1 to 15 parts by mass of the aromatic polyvalent carboxylic acid ester (B), 5 to 100 parts by mass of the dimensional accuracy improver (C-1), and 0 to 150 parts by mass of the dimensional accuracy improver (C-2).