JP2008006829A - Insert molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert molded article with such a sufficient thermal shock resistance as being unbroken by an ordinary temperature change. <P>SOLUTION: The insert molded article is obtained by insert molding a polyester resin composition and a metal or an inorganic solid, wherein the resin composition comprises, a thermoplastic polyester resin (A) with 1-25 wt.% (to the total amount of the composition) of a crash-proofing agent (B) selected from a styrene elastomer, a polyester elastomer and a core-shell polymer, 1-50 wt.% (to the total amount of the composition) of an inorganic filler (C), and 0.1-10 wt.% (to the total amount of the composition) of an aromatic polyvalent carboxylate (D). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insert-molded article excellent in thermal shock characteristics, which is formed by insert-molding a polyester resin composition and a metal or an inorganic solid.

  The insert molding method is a molding method in which metal or the like is embedded in the resin in order to use the characteristics of the resin and the properties of the material of the metal or inorganic solid (hereinafter abbreviated as metal). It has been applied to a wide range of parts and is now one of the common molding methods. However, since the expansion and contraction rate (so-called linear expansion coefficient) due to temperature changes are extremely different between resin and metal, etc., the resin part of the molded product is thin, or there is a part with a large change in thickness and metal Etc. have sharp corners, they often have troubles such as cracking immediately after molding or cracking due to temperature changes during use. For this reason, the current situation is that the application and the shape of the molded product are considerably limited.

  Recently, plastics around engines have been developed in the field of the automobile industry, and insert molded products have become important parts. In particular, in the ignition system and distributor parts, insert molded products in which metal parts such as aluminum, copper, iron, and brass are wrapped in thermoplastic polyester resin are being studied. This is because the structure of the insert parts is complicated. In addition to the fact that there are many thickness change portions of the resin, since the place of use is in the vicinity of the engine and the temperature change is high, the performance required for the insert molded product is higher. Accordingly, recently, there is a strong demand for resins that can withstand long-term changes in temperature, that is, resins having excellent thermal shock characteristics.

In view of the above-mentioned problems, the present inventors diligently studied to obtain a thermoplastic resin excellent in thermal shock characteristics from which an insert-molded product that does not crack due to temperature change can be obtained. As a result, a composition mainly composed of a thermoplastic polyester resin and blended with a specific impact resistance imparting agent, an inorganic filler, and an aromatic ester compound is extremely excellent in thermal shock characteristics, and an insert molded product using the composition. Has found that it has sufficient thermal shock resistance that does not crack under normal temperature changes, and has completed the present invention.
That is, the present invention
(A) To thermoplastic polyester resin,
(B) 1 to 25% by weight of one or more impact resistance imparting agents selected from styrene elastomers, polyester elastomers, and core-shell polymers (based on the total amount of the composition)
(C) 1-50% by weight of inorganic filler (based on the total composition)
(D) Aromatic polyvalent carboxylic acid ester 0.1 to 10% by weight (based on the total amount of the composition)
Is an insert-molded product formed by insert-molding a polyester resin composition formed by blending a metal or an inorganic solid.

  The insert-molded article of the present invention can withstand long-term high and low temperature changes, and is suitable for use in, for example, automobile parts, particularly in the vicinity of an engine.

  Hereinafter, the present invention will be described in detail. First, (A) the thermoplastic polyester resin which is the base resin of the present invention is a polyester obtained by polycondensation of a dicarboxylic acid compound and a dihydroxy compound, polycondensation of an oxycarboxylic acid compound, or polycondensation of these ternary compounds. It may be either a homopolyester or a copolyester. Examples of the dicarboxylic acid compound constituting the (A) thermoplastic polyester resin used here include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, These are known dicarboxylic acids such as adipic acid and sebacic acid, and alkyl, alkoxy or halogen substituted products thereof. These dicarboxylic acid compounds can also be used for polymerization in the form of an ester-forming derivative, for example, a lower alcohol ester such as dimethyl ester.

  Next, examples of the dihydroxy compound constituting the thermoplastic polyester resin (A) of the present invention include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, hydroquinone, resorcin, dihydroxyphenyl, naphthalenediol, dihydroxyphenyl ether. , Cyclohexanediol, 2,2-bis (4-hydroxyphenyl) propane, dihydroxy compounds such as diethoxylated bisphenol A, polyoxyalkylene glycols and their alkyl, alkoxy, or halogen-substituted products, and one or more of them Can be used mixed. Examples of oxycarboxylic acid compounds include oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid, and diphenyleneoxycarboxylic acid, and alkyl, alkoxy, or halogen substituted products thereof. In addition, derivatives capable of forming an ester of these compounds can also be used. In the present invention, one or more of these compounds are used. In addition to these, a polyester having a branched or crosslinked structure in which a trifunctional monomer, that is, trimellitic acid, trimesic acid, pyromellitic acid, pentaerythritol, trimethylolpropane, or the like is used in a small amount may be used.

  In the present invention, any of the thermoplastic polyesters produced by polycondensation can be used as the component (A) of the present invention, using the compound as described above as a monomer component, and used alone or in admixture of two or more. However, preferably polyalkylene terephthalate, more preferably polybutylene terephthalate and a copolymer based on this are used. In the present invention, a thermoplastic polyester may be modified by a known method such as crosslinking or graft polymerization.

  Next, the (B) impact resistance-imparting agent used in the present invention is a thermoplastic elastomer or core-shell polymer selected from styrene elastomers and polyester elastomers. Such a thermoplastic elastomer or the like is a general term for a high-molecular substance that can be melt-mixed with a thermoplastic polyester resin because it is a solid having rubber-like elasticity at room temperature, but its viscosity decreases when heated.

  Examples of the styrene elastomer include a block copolymer composed of a polymer block mainly composed of a vinyl aromatic compound such as styrene and a polymer block mainly composed of an unhydrogenated and / or hydrogenated conjugated diene compound. . Examples of the vinyl aromatic compound constituting the block copolymer include styrene, α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene, 1,1-diphenylstyrene, and the like. One or two or more types can be selected from among them, and styrene is preferable among them. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, pyrylene, 3-butyl-1,3-octadiene, phenyl-1,3- One or two or more types are selected from butadiene and the like, and among them, butadiene, isoprene and combinations thereof are preferable. The block copolymer here is a block copolymer composed of a polymer block A mainly composed of a vinyl aromatic compound and a polymer block B mainly composed of a conjugated diene compound. The copolymerization ratio of the conjugated diene compound is 5/95 to 70/30, and a polymerization ratio of 10/90 to 60/40 is particularly preferable.

  The number average molecular weight of the block copolymer used in the present invention is in the range of 5000 to 600,000, preferably 10,000 to 500,000, and the molecular weight distribution [the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is ( Mw / Mn)] is 10 or less. The molecular structure of the block copolymer may be linear, branched, radial, or any combination thereof. For example, it is a vinyl aromatic compound-conjugated diene compound block copolymer having a structure such as A-B-A, B-A-B-A, (A-B-) 4Si, or A-B-A-B-A. Furthermore, the unsaturated bond of the conjugated diene compound of the block copolymer may be partially hydrogenated.

  As a manufacturing method of the block copolymer to be used in the present invention, any manufacturing method can be used as long as the block copolymer having the structure described above is obtained. For example, a vinyl aromatic compound-conjugated diene compound block in an inert solvent using a lithium catalyst or the like by the method described in JP-B-40-23798, JP-B-43-17979, JP-B-56-28925. Copolymers can be synthesized. Further, hydrogenation is carried out in the presence of a hydrogenation catalyst in an inert solvent by the method described in JP-B-42-8704, JP-B-43-6636, or JP-B-59-133203. Partially hydrogenated block copolymers for use in the invention can be synthesized.

  In the present invention, an epoxy-modified block copolymer used in the present invention can be obtained by epoxidizing the above-mentioned block copolymer. The epoxy-modified block copolymer in the present invention can be obtained by reacting the above block copolymer with an epoxidizing agent such as hydroperoxides and peracids in an inert solvent. Hydroperoxides include hydrogen peroxide, tertiary butyl hydroperoxide, cumene peroxide, and the like. Examples of peracids include performic acid, peracetic acid, perbenzoic acid, and trifluoroperacetic acid. Of these, peracetic acid is a preferred epoxidizing agent because it is industrially produced in large quantities, is available at low cost, and has high stability.

  In the epoxidation, a catalyst can be used as necessary. For example, in the case of a peracid, an alkali such as sodium carbonate or an acid such as sulfuric acid can be used as a catalyst. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda in combination with hydrogen peroxide or molybdenum hexacarbonyl in combination with tertiary butyl hydroperoxide. There is no strict regulation of the amount of epoxidizing agent, and the optimum amount in each case depends on variables such as the particular epoxidizing agent used, the desired degree of epoxidation, and the particular block copolymer used.

  As the inert solvent, it can be used for the purpose of reducing the viscosity of the raw material and stabilizing by dilution of the epoxidizing agent. it can. Particularly preferred solvents are hexane, cyclohexane, toluene, benzene, ethyl acetate, carbon tetrachloride, and chloroform. There are no strict regulations on the epoxidation reaction conditions. The reaction temperature range that can be used is determined by the reactivity of the epoxidizing agent used. For example, in the case of peracetic acid, 0 to 70 ° C. is preferable. If it is lower than 0 ° C., the reaction is slow, and if it exceeds 70 ° C., decomposition of peracetic acid occurs. Moreover, in the tertiary butyl hydroperoxide / molybdenum dioxide diacetylacetonate system which is an example of hydroperoxide, 20-150 degreeC is preferable for the same reason. No special operation of the reaction mixture is necessary. For example, the mixture may be stirred for 2 to 10 hours. Isolation of the obtained epoxy-modified copolymer is an appropriate method, for example, a method of precipitation with a poor solvent, a method of pouring the polymer into hot water with stirring and distilling off the solvent, a direct desolvation method, etc. Can be done.

  The epoxy equivalent of the epoxy-modified block copolymer is preferably 140 to 2700 g / mol, particularly preferably 200 to 2000 g / mol. When the epoxy equivalent exceeds 2700 g / mol, the compatibility is not sufficient and phase separation tends to occur. On the other hand, if it is less than 140 g / mol, side reactions such as gelled products are liable to occur during the isolation of the polymer.

  Examples of polyester elastomers include aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate as hard segments, polyethers such as polyethylene glycol and polytetramethylene glycol, and aliphatic polyesters such as polyethylene adipate, polybutylene adipate, and polycaprolactone. Although the block copolymer used as a segment is mentioned, it is not limited to this.

  On the other hand, the core-shell polymer is a core-shell type graft copolymer having a multilayer structure and preferably including a rubber layer having an average particle size of 1.0 μm or less and a glassy resin. As the rubber layer of the core-shell type copolymer, those having an average particle size of 1.0 μm or less can be used, and a preferred range is 0.2 to 0.6 μm. If the average particle size of the rubber layer exceeds 1.0 μm, the impact resistance improvement effect may be insufficient. As the rubber layer of the core-shell type copolymer, a silicon-based, diene-based, or acrylic-based elastomer alone or a copolymer obtained by copolymerizing / grafting two or more kinds of elastomer component systems selected from these can be used.

  The silicon-based elastomer is produced by polymerizing an organosiloxane monomer. Examples of the organosiloxane include hexamethyltricyclosiloxane, octamethylcyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane, Trimethyltriphenylsiloxane, tetramethylphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and the like are used. The acrylic rubber can be obtained by polymerizing an acrylate ester such as butyl acrylate and a small amount of a crosslinkable monomer such as butylene diacrylate.

  Examples of the acrylic ester include methyl acrylate, ethyl acrylate, propyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate in addition to butyl acrylate. Moreover, as a crosslinkable monomer, in addition to butylene diacrylate, polyols such as butylene dimethacrylate and trimethylolpropane and acrylic esters, vinyl compounds such as divinylbenzene, vinyl acrylate and vinyl methacrylate, allyl acrylate, Examples include allyl compounds such as allyl methacrylate, diallyl malate, diallyl fumarate, diallyl itanilate, monoallyl malate, monoallyl fumarate, triallyl cyanurate. Examples of the diene rubber include polybutadiene obtained by polymerizing a butadiene monomer.

  Further, a vinyl polymer is used for a shell layer formed of a glassy resin of a core-shell type copolymer. The vinyl polymer is obtained by polymerizing at least one monomer selected from an aromatic vinyl monomer, a vinyl cyanide monomer, a methacrylic ester monomer, and an acrylate monomer. Obtained by copolymerization. The rubber layer and shell layer of such a core-shell type copolymer are usually bonded by graft copolymerization. If necessary, this graft copolymerization is obtained by adding a graft crossing agent that reacts with the shell layer during polymerization of the rubber layer, giving a reactive group to the rubber layer, and then forming the shell layer. As the graft-crossing agent, organosiloxane having a vinyl bond or organothiol having a thiol is used for the silicone rubber, and preferably, acoxysiloxane, methacryloxysiloxane, or vinylsiloxane is used.

  Examples of the core-shell polymer as described above include Kanease FM manufactured by Kaneka Chemical, Metablene W-300, W-530, S-2001 manufactured by Mitsubishi Rayon, Acryloid KM-323, KM-330 manufactured by Rohm and Haas, Kureha Chemical Co., Ltd. Paraloid EXL-2311, -2602, -3211, and Staphyloid P-3267 (trademark) manufactured by Takeda Pharmaceutical.

  In the present invention, the blending amount of the component (B) impact resistance imparting agent is 1 to 25% by weight, preferably 2 to 20% by weight, and more preferably 3 to 15% by weight in the total composition. If the amount of the component (B) is too small, the high thermal shock characteristics intended by the present invention cannot be obtained, and if it is too large, mechanical properties such as rigidity are hindered. One or two or more impact resistance imparting agents can be used in combination.

  Next, the inorganic filler of the component (C) used in the present invention is an essential component for reducing the molding shrinkage rate and linear expansion coefficient of the molded article and improving the high and low temperature impact resistance. Accordingly, various fillers such as fibrous and non-fibrous (powder and plate) are used. Among these fillers, the fibrous filler includes glass fiber, irregular glass, asbestos fiber, carbon fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber. Furthermore, metal fibrous substances such as stainless steel, aluminum, titanium, copper, and brass are mentioned. Particularly typical fibrous fillers are glass fibers or carbon fibers. On the other hand, as granular fillers, silicates such as carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, iron oxide, titanium oxide, zinc oxide And oxides of metals such as alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, and various metal powders. Examples of the plate-like filler include mica, glass flakes, various metal foils and the like. These inorganic fillers can be used alone or in combination of two or more. When using these inorganic fillers, it is desirable to treat with a sizing agent or a surface treatment agent if necessary.

  The blending amount of the inorganic filler (C) in the present invention is 1 to 50% by weight in the composition, preferably 10 to 45% by weight, and more preferably 20 to 40% by weight. If the amount of filler used is too small, the effect of improving thermal shock resistance is small, and if it is too large, the molding operation becomes difficult.

  The (D) aromatic polycarboxylic acid ester used in the present invention is a compound represented by the following general formula.

(In the formula, X represents -COOR, R represents an alkyl group, n represents an integer of 2 to 4. R in each X may be the same or different.)
In particular, when n is 3 or more, heat resistance is high and more preferable. As the component (D), for example, trimellitic acid ester and pyromellitic acid ester are preferable examples. Examples of the alkyl group constituting the alkyl ester include a trioctyl group, a triisodecyl group, a tris (2-ethylhexyl) group, a tributyl group, and the like. The alkyl ester is composed of at least one of these alkyl groups. . Such aromatic polyvalent carboxylic acid esters can be used alone or in combination of two or more.

  The blending amount of (D) aromatic polycarboxylic acid ester in the present invention is 0.1 to 10% by weight, preferably 0.5 to 7% by weight, particularly preferably 1 to 5% by weight in the composition. If the amount of the aromatic polycarboxylic acid ester is too small, the thermal shock characteristics are not sufficient, and if it is too large, the physical properties such as rigidity are impaired, and the aromatic ester oozes out on the surface of the molded product. .

  In the present invention, in addition to the above components, other thermoplastic resin components can be supplementarily used in a small amount depending on the purpose. Any other thermoplastic resin may be used as long as it is stable at high temperatures. Examples thereof include polyamide, polycarbonate, polyphenylene sulfide, polyphenylene oxide, polyacetal, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polysulfone, polyethersulfone, polyetherimide, polyetherketone, and fluorine resin. These thermoplastic resins can also be used as a mixture of two or more.

  Furthermore, in order to give the resin composition of the present invention desired properties according to its purpose, known substances generally added to thermoplastic resins and thermosetting resins, that is, antioxidants, ultraviolet absorbers, etc. Stabilizers, antistatic agents, colorants such as dyes and pigments, lubricants, mold release agents, crystallization accelerators, crystal nucleating agents, and the like can be blended.

  The composition of the present invention is easily prepared by a known equipment and method generally used as a conventional resin composition preparation method. For example, i) a method of mixing each component and then kneading and extruding with an extruder to prepare pellets, and then molding, ii) once preparing pellets with different compositions, mixing the pellets in a predetermined amount for molding Any method can be used, such as a method of obtaining a molded product having the desired composition after the forming and iii) a method of directly charging one or more of each component into a molding machine. Further, mixing a part of the resin component as a fine powder with other components and adding it is a preferable method for uniformly blending these components.

  The insert molded product referred to in the present invention is a compound molded product in which a metal or the like is mounted in advance on a molding die and the resin composition is filled on the outside thereof. As a molding method for filling the resin with the mold, there are an injection molding method, an extrusion molding method, a compression molding method and the like, and the injection molding method is general. In addition, since the material to be inserted into the resin is used for the purpose of taking advantage of its characteristics and compensating for the defects of the resin, a material that does not change its shape or melt when it comes into contact with the resin during molding is used. For this reason, mainly used are metals such as aluminum, magnesium, copper, iron, brass and their alloys, and inorganic solids such as glass and ceramics, which are previously formed into rods, pins, screws and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

The thermal shock characteristics were evaluated as follows. That is, pellets of the resin composition were placed in a square mold with 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. , 18 mm long, 18 mm wide, 30 mm high insert metal mold) was insert injection molded so that the minimum thickness of some resin parts was 1 mm to produce an insert molded product. The process of heating the resulting insert molded product to 140 ° C using a thermal shock tester after heating at 140 ° C for 1 hour 30 minutes, cooling to -40 ° C, cooling for 1 hour 30 minutes, A thermal shock test for cycling was performed. The number of cycles until cracks occurred in 10 molded products was measured, and the average value was defined as the thermal shock life, and the thermal shock characteristics were evaluated. A larger value of thermal shock life means higher thermal shock characteristics.
Examples 1-6, Comparative Examples 1-6
After the components (A) to (D) having the compositions shown in Table 1 were melt-kneaded with an extruder and pelletized, the thermal shock characteristics were evaluated as described above. The evaluation results are also shown in Table 1.

The details of each component used are as follows.
・ (A) Thermoplastic polyester resin Polybutylene terephthalate (PBT); Intrinsic viscosity 0.75, manufactured by Polyplastics Co., Ltd. (B) Impact resistance imparting agent
(B1) Acrylic core-shell polymer; Kureha Chemical Industry Co., Ltd., trade name Paraloid EXL-2311
(B2) Methyl methacrylate-butadiene-styrene copolymer resin (MBS); manufactured by Kureha Chemical Industry Co., Ltd., trade name Paraloid EXL2602
(B3) Epoxidized modified styrene-butadiene-styrene block copolymer (ESBS); manufactured by Daicel Chemical Industries, Ltd., trade name Epofriend A1010
・ (C) Inorganic filler
(C1) Glass fiber (diameter 10μm)
(C2) Glass flake (thickness about 3μm, center particle size about 300μm)
・ (D) Aromatic polyvalent carboxylic acid ester
(D1) trimellitic acid ester; manufactured by Daihachi Chemical Industry Co., Ltd., trade name TOTM
(D2) pyromellitic acid ester; manufactured by Asahi Denka Kogyo Co., Ltd., trade name: Adeka Sizer UL-100

  As shown in Table 1, when Comparative Example 1 and Comparative Examples 2 and 5 to 6 are compared, it can be seen that thermal shock characteristics are improved by adding an impact resistance imparting agent. In addition, Comparative Example 1 and Comparative Example 3 Comparing ˜4, it can be seen that the thermal shock characteristics can be improved to some extent by adding an aromatic polycarboxylic acid ester. On the other hand, as is clear from the examples in Table 1, when the impact resistance-imparting agent and the aromatic polycarboxylic acid ester are used in combination, the thermal shock is much higher than expected from the effect of improving the individual thermal shock characteristics. It can be seen that the characteristics can be obtained.

Claims (4)

(A) To thermoplastic polyester resin,
(B) 1 to 25% by weight of one or more impact resistance imparting agents selected from styrene elastomers, polyester elastomers, and core-shell polymers (based on the total amount of the composition)
(C) 1-50% by weight of inorganic filler (based on the total composition)
(D) Aromatic polyvalent carboxylic acid ester 0.1 to 10% by weight (based on the total amount of the composition)
An insert-molded product obtained by insert-molding a polyester resin composition obtained by blending a metal or an inorganic solid.   The insert molded article according to claim 1, wherein (A) the thermoplastic polyester resin is a resin mainly composed of polybutylene terephthalate.   The insert molded article according to claim 1 or 2, wherein the aromatic polyvalent carboxylic acid ester (D) is one or more selected from trimellitic acid ester and pyromellitic acid ester.   (B) The insert molded article according to any one of claims 1 to 3, wherein the impact resistance-imparting agent is an epoxy-modified styrene block copolymer or a core-shell polymer.