JP2001288236A - Composite molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite molded article which is excellent in mechanical properties and stiffness, exhibits improvement effects on creep fracture life and heat shock life due to the improvement in creep fracture properties, and is produced by insert molding or outsert molding of a polyacetl resin. SOLUTION: In this article prepared by integrally molding a rigid member and a resin by insert molding or outsert molding, a branched polyacetal copolymer having oxymethylene groups as the main repeating units and specific branch units is used as the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite molded article made of a branched polyacetal resin having excellent creep resistance.

[0002]

2. Description of the Related Art Polyacetal resins have excellent properties in mechanical properties, thermal properties, electrical properties, slidability, moldability, and the like. Widely used for parts, precision machine parts, etc. However, with the expansion of the field in which polyacetal resin is used, further improvement in rigidity and creep resistance may be required. For example, the insert molding method is a molding method in which a metal or the like is embedded in a resin in order to use the resin by utilizing the characteristics of a resin and the characteristics of a material of a metal or an inorganic solid (hereinafter sometimes abbreviated as a metal or the like). It has been applied to a wide range of fields such as electrical and electronic parts and OA equipment parts, and is now one of the general molding methods. However, usually, the resin shrinks due to molding shrinkage peculiar to the resin after molding, and as a result of tightening the embedded metal or the like, a stress is generated in the resin. Since the so-called linear expansion coefficient) is extremely different, the molded products are thinner, those with large thickness changes and those with sharp corners of metal etc. There are many troubles such as temperature change or creep destruction over time even if the temperature is constant. In recent years, resin molding around the engine and around the door has advanced in the automotive field, and insert molded products have become an important part. In particular, for ignition systems, distributor parts, and window elevating mechanisms, insert molded products that are wrapped in thermoplastic resin along with metal products such as aluminum, copper, iron, and brass have been studied. In addition to having a complicated structure and many parts where the thickness of the resin changes, in addition to the place where it is used near the engine or inside the door where heat is easily stored by direct sunlight, there are large changes in high and low temperatures,
There has been a strong demand for a resin that can withstand long-term high and low temperature changes, that is, a resin having excellent high and low temperature impact characteristics. To meet such demands, various elastomers,
A polyester resin to which an olefin-based elastomer or the like is added has been proposed, and a certain effect has been recognized. However, these elastomer-added materials are effective but not sufficient for the intended improvement of the intended high- and low-temperature impact properties, and have the drawback that the viscosity at the time of melting increases and the injection moldability deteriorates. Was. Particularly, in the case of an electronic component in which the component encapsulated by the resin is fragile, fatal damage may be caused by pressure during molding, and a resin excellent in both fluidity and high / low temperature impact characteristics is strongly demanded.

On the other hand, an outsert molded product is a molded product substantially similar to an insert molded product, which is a molded product obtained by integrating a hard substrate made of metal or the like and a thermoplastic resin, and is a tape recorder, a video tape, or the like. It is used for various chassis typified by chassis of recorders (VTRs), switch boards, and the like. However, in the case of an outsert molded product, when placed in a high-temperature atmosphere or a heat cycle atmosphere, for the same reason as in the case of an insert molded product, creep destruction occurs in the runner portion connecting the resin functional parts, Extremely, there is a problem that creep destruction occurs also in functional parts. As a method of preventing creep destruction of the runner portion, a method of providing an S-shaped portion in the runner portion and providing a mechanism for absorbing and dispersing stress is used, but the design of a molded product is restricted. There is a problem.

[0004] As a means for mainly improving the creep resistance characteristics, a method of filling a polyacetal resin with a fibrous filler, and in a polyacetal copolymer, the strength is improved by reducing the amount of comonomer and increasing the degree of crystallization. Methods and the like are known. However, filling with fibrous fillers causes problems such as poor appearance of molded products and deterioration of sliding characteristics, and problems with the method of reducing comonomer decrease such as thermal stability of polymers. The goods could not be obtained.

[0005] In view of the problems of the prior art, the present invention provides a composite by insert molding or outsert molding using a polyacetal resin by improving the intrinsic rigidity and creep characteristics of the polymer by modifying the polymer skeleton itself. The purpose is to improve the creep resistance of the molded article.

With respect to such modification of the polymer skeleton of the polyacetal resin, JP-A-3-170526 and the like disclose trioxane, ethylene oxide, 1,3-
Dioxolan, 1,3-dioxepane, 1,3,5-trioxepane, at least one cyclic ether compound selected from 1,3,6-trioxocan and at least one selected from glycidyl phenyl ether, styrene oxide and glycidyl naphthyl ether A modified polyacetal copolymer obtained by copolymerizing one compound is disclosed. However, this modified polyacetal copolymer is intended to improve the moldability by increasing the crystallization rate, particularly for high cycle properties, and hardly discloses other properties.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to improve the creep rupture characteristics of polyacetal while maintaining various characteristics such as rigidity and slidability of polyacetal. It is an object of the present invention to provide a composite molded product by insert molding or outsert molding using the same.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors conducted detailed investigations into the molecular skeleton or resin physical properties of a polyacetal resin.
The inventors have found a polymer skeleton effective for achieving the object, and have completed the present invention.

That is, the present invention provides a composite molded article in which a hard member and a resin are integrated by insert molding or outsert molding, wherein the resin is represented by the following general formula (I), wherein an oxymethylene group is a main repeating unit. The present invention relates to a composite molded article using a branched polyacetal copolymer having a branch unit.

[0010]

Embedded image

Wherein m and n each represent an integer of 0 to 5, and m + n is 1 to 5. R has a molecular weight of 40 to 1000.
Represents a monovalent organic group. )

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a composite molded article of the present invention will be described in detail. First, a branched polyacetal copolymer used as a base resin of a composite molded article in the present invention is:
It has an oxymethylene group (—CH ₂ —O—) as a main repeating unit, and has a branch unit represented by the following general formula (I). The presence of such a branch unit is a factor for achieving the object of the present invention. It is one of the important factors. The object of the present invention cannot be achieved by using a normal polyacetal resin having no branching unit.

[0013]

Embedded image

(M and n each represent an integer of 0 to 5, and m + n is 1 to 5. R represents a monovalent organic group having a molecular weight of 40 to 1000.) Formula (I) In the branching unit, R as a branching group is a monovalent organic group having a molecular weight of 40 to 1,000. When the molecular weight of R is less than 40, improvement in rigidity and creep resistance cannot be expected, and when the molecular weight exceeds 1,000, there is a problem of a decrease in crystallinity. Preferably, the molecular weight of R is between 50 and 500. The monovalent organic group forming R preferably has an aromatic ring, and has a remarkable effect on improving rigidity.

From the viewpoint of improving rigidity and creep rupture characteristics and maintaining other physical properties, the branching unit represented by the general formula (I) is preferably randomly present in the polymer skeleton. Oxymethylene unit (-CH ₂ O-) 100
The amount is preferably 0.001 to 10 parts by weight, particularly preferably 0.01 to 3 parts by weight based on part by weight.

The production method of the branched polyacetal copolymer used as the resin material of the composite molded article of the present invention is not particularly limited, but trioxane (a) 100 parts by weight,
Monofunctional glycidyl compound (b) 0.001 to 10 parts by weight and cyclic ether compound (c) copolymerizable with trioxane 0
~ 20 parts by weight are preferably obtained by copolymerization, and the branched polyacetal copolymer comprising such a monomer component is easy to produce, and has the characteristic that the properties of a composite molded article comprising the obtained copolymer are excellent. Have.

The trioxane (a) used here is a cyclic trimer of formaldehyde, which is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and which is obtained by a method such as distillation. It is used after purification. Trioxane (a) used for polymerization is water,
Those containing as little as possible impurities such as methanol and formic acid are preferred. Next, the monofunctional glycidyl compound (b) is a generic term for an organic compound having one glycidyl group in the molecule, for example, glycidol, aliphatic alcohol or aromatic alcohol, or (poly) alkylene glycol thereof. Typical examples include glycidyl ethers composed of an adduct and glycidol, aliphatic carboxylic acids or aromatic carboxylic acids, and glycidyl esters composed of these (poly) alkylene glycol adducts and glycidol. Such a monofunctional glycidyl compound (b)
Is used as a branched component of the branched polyacetal copolymer (A) used in the present invention. Examples of the monofunctional glycidyl compound (b) include the compounds represented by the general formulas (II) and (II).
The glycidyl ether compounds represented by I) and (IV) are preferred. Specific examples include methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 2-methyloctyl glycidyl ether, phenyl glycidyl ether, p Tertiary butyl phenyl glycidyl ether, sec-butyl phenyl glycidyl ether,
Examples thereof include n-butylphenyl glycidyl ether, phenylphenol glycidyl ether, cresyl glycidyl ether, dibromocresyl glycidyl ether, glycidyl ether composed of (poly) ethylene glycol adduct of aliphatic alcohol or aromatic alcohol and glycidol, and the like. Further, specific examples of the glycidyl ester compound include glycidyl acetate, glycidyl stearate and the like. Among such monofunctional glycidyl compounds, those having an aromatic ring are preferred. Among them, those represented by the general formulas (II) and (III),
Those having a substituent R ¹ or R ³ at the ortho position are preferred. As such a substituent, those having 4 or more carbon atoms are preferable,
Particularly preferred are those having an aromatic ring. Specific examples include o-phenylphenol glycidyl ether.

In the production of the polyacetal copolymer as the resin material of the composite molded article of the present invention, the amount of the monofunctional glycidyl compound (b) to be copolymerized is controlled by the trioxane component (a).
The amount is 0.001 to 10 parts by weight, preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight based on 100 parts by weight. If the copolymerization amount of the component (b) is too small, the effect of improving physical properties, which is the main object of the present invention, cannot be obtained. There is a possibility that a problem of moldability may occur due to deterioration of the moldability. Further, as the monofunctional glycidyl compound (b), a compound having a molecular weight of 100 to 1,000 is preferably used. If the molecular weight of the monofunctional glycidyl compound (b) is too large, the branched chain of the branched polyacetal copolymer produced by the copolymerization will become long, disturbing the crystallinity of the resin, etc. This can also have undesirable effects. Conversely, if the molecular weight of the component (b) is too small, the effects of the present invention on improving rigidity and improving creep rupture characteristics will be extremely small.

The polyacetal copolymer serving as the resin material of the composite molded article of the present invention is preferably a copolymer obtained by further adding a cyclic ether compound (c) copolymerizable with trioxane as a copolymerization component. Such a cyclic ether compound (c) is not particularly essential for improving the rigidity and creep rupture properties aimed at by the present invention.
In order to stabilize the polymerization reaction when producing a branched polyacetal copolymer and to increase the thermal stability of the resulting branched polyacetal copolymer, it is extremely effective to use such a cyclic ether compound as a copolymer component. is there.

The cyclic ether compound (c) copolymerizable with trioxane includes ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxetane,
3,3-bis (chloromethyl) oxetane, tetrahydrofuran, trioxepane, 1,3-dioxolan, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol Formal, 1,
6-hexanediol formal and the like. Among them, ethylene oxide, 1,3-dioxolan, diethylene glycol formal, and 1,4-butanediol formal are preferred. In the branched polyacetal copolymer used in the present invention, the copolymerization amount of the cyclic ether compound (c) is 0 to 20 parts by weight, preferably 0.05 to 15 parts by weight, per 100 parts by weight of the component (a), trioxane. Parts, particularly preferably 0.1 to 10 parts by weight. If the copolymerization ratio of the cyclic ether compound (c) is too small, the copolymerization reaction becomes unstable and the thermal stability of the resulting branched polyacetal copolymer becomes poor. When the polymerization ratio is excessive, mechanical properties such as rigidity and strength, which are one of the object characteristics of the present invention, are reduced and become insufficient.

The polyacetal copolymer used as the resin material of the composite molded article of the present invention basically comprises the above trioxane (a), monofunctional glycidyl compound (b) and cyclic ether compound (c), if necessary. Then, an appropriate amount of a molecular weight modifier is added, and bulk polymerization is performed using a cationic polymerization catalyst.

Examples of the molecular weight modifier include low molecular weight acetal compounds having an alkoxy group such as methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal, and oxymethylene di-n-butyl ether; and alcohols such as methanol, ethanol and butanol. Kind,
Ester compounds and the like are exemplified. Among them, a low molecular weight acetal compound having an alkoxy group is particularly preferable. The amount of these molecular weight modifiers is not particularly limited as long as the effects of the present invention are not impaired.

As the cationic polymerization catalyst, lead tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride,
Zinc chloride, vanadium trichloride, antimony trichloride, phosphorus pentafluoride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, trifluoride Boron trifluoride coordination compound such as boron trifluoride triethylamine complex compound, boron trichloride, t-butyl perchlorate, t-butyl perchlorate, hydroxyacetic acid, trichloroacetic acid,
Trifluoroacetic acid, inorganic and organic acids such as p-toluenesulfonic acid, triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate,
Complex salt compounds such as allyldiazonium hexafluorophosphate and allyldiazonium tetrafluoroborate,
Alkyl metal salts such as diethylzinc, triethylaluminum, diethylaluminum chloride and the like, heteropoly acids, isopoly acids and the like can be mentioned. Among them, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dibutyl etherate, boron trifluoride dioxanate, boron trifluoride acetic anhydrate, boron trifluoride triethylamine complex compound, etc. Boron fluoride coordination compounds are preferred. These catalysts can be used after being diluted with an organic solvent or the like in advance.

The branched polyacetal copolymer used as the resin material of the composite molded article of the present invention may be a monofunctional glycidyl compound (b) in the molecular chain of the polyacetal copolymer.
And the structural units derived from the cyclic ether compound (c) are desirably dispersed uniformly. For this purpose, the glycidyl compound (b) and the cyclic ether compound (c) are prepared in advance in the production of the polyacetal copolymer by polymerization. ) And the catalyst are mixed homogeneously, and this is added to a melt of trioxane (a) separately supplied to the polymerization machine for polymerization, or the homogeneous mixture is further mixed with trioxane (a), Is effective. In particular, the reaction rate of the glycidyl compound (b) is often slower than that of the other components (a) and (c),
It is extremely effective to mix the component (b) and the catalyst in advance. In this way, by preliminarily mixing and maintaining a uniform solution state, the dispersion state of the branched structure derived from the glycidyl compound is improved.

In producing the polyacetal copolymer to be used as the resin material of the composite molded article of the present invention, the polymerization apparatus is not particularly limited, and a known apparatus may be used, and may be any of a batch type, a continuous type, and the like. A method is also possible. Also,
The polymerization temperature is preferably maintained at 65 to 135 ° C. Deactivation after polymerization is a product reaction product discharged from the polymerization machine after the polymerization reaction, or a basic compound in the reaction product in the polymerization machine,
Alternatively, the treatment is performed by adding the aqueous solution or the like. As the basic compound for neutralizing and deactivating the polymerization catalyst, ammonia,
Or amines such as triethylamine, tributylamine, triethanolamine and tributanolamine;
Alternatively, hydroxide salts of alkali metals and alkaline earth metals, and other known catalyst deactivators are used. After the polymerization reaction, it is preferable to add these aqueous solutions to the product promptly to deactivate the product. After such a polymerization method and a deactivation method, if necessary, washing, separation and recovery of unreacted monomers, drying, etc. are performed by a conventionally known method.

The degree of polymerization of the polyacetal copolymer obtained as described above and serving as the resin material of the composite molded article of the present invention is not particularly limited, and the degree of polymerization depends on the purpose of use and the molding means. Adjustment is possible, but when used for molding, the melt index (MI) measured at a temperature of 190 ° C. and a load of 2.06 kg is preferably from 1 to 100 g / 10 min, particularly preferably from 2 to 90 g / 10 min. Minutes.

The mechanism by which the branched polyacetal copolymer used as the base resin material of the composite molded article of the present invention exhibits excellent effects in rigidity and creep resistance is not always clear, but the present inventors have roughly described the following. Infer. In a polyacetal polymer which is a crystalline resin, molecules are folded during a process of cooling and solidifying from a molten state in molding or the like, and have a lamellar structure. When a load such as bending or pulling is applied to the molded product,
Slip occurs at the lamellar interface, strain occurs, and stress relaxation occurs, but when the limit is exceeded, destruction occurs. On the other hand, since the polyacetal copolymer used as the material of the molded article of the present invention has a branched structure, the branch portion of the polymer molecule constituting one lamella is entangled with the polymer molecule constituting the adjacent lamella or the lamella It is presumed that the anchor effect occurs by being inserted into the inside, the resistance to slip at the lamella interface under stress increases, and contributes to the improvement of rigidity and creep rupture characteristics of the composite molded article,
Further, it is presumed that an appropriate branch length or an appropriate molecular weight branch derived from the monofunctional glycidyl compound (b) used in the present invention is a factor that causes a further effect associated with the above mechanism. .

It is preferable that the polyacetal copolymer used as the resin material of the composite molded article of the present invention contains various stabilizers selected as necessary. Hindered phenol compounds, nitrogen-containing compounds,
Hydroxides and inorganic salts of alkali or alkaline earth metals,
Any one kind or two or more kinds of carboxylate and the like can be mentioned. Further, the polyacetal copolymer serving as the resin material of the composite molded article of the present invention, if necessary, as long as the purpose and effect are not hindered, general additives to the thermoplastic resin, such as dyes and pigments. One or more of a coloring agent, a lubricant, a release agent, an antistatic agent, a surfactant, and an organic polymer material can be added.

The polyacetal copolymer used as the resin material of the composite molded article of the present invention may be blended with one or two types of known fibrous, powdery, plate-like or hollow fillers. it can. As the fibrous filler, glass fiber,
Various fibers such as carbon fibers, whiskers, metal fibers, inorganic fibers and ore fibers can be used. Examples of the powdery filler include kaolin, clay, vermiculite, talc, calcium silicate, aluminum silicate, feldspar powder, acid clay, lauric clay, sericite, sillimanite, bentonite, glass powder, glass beads, slate powder, silane, etc. Silicate, calcium carbonate, chalk, barium carbonate,
Magnesium carbonate, carbonates such as dolomite, baryte powder, blankix, precipitated calcium sulfate, plaster,
Sulfates such as barium sulfate, hydroxides such as hydrated alumina,
Alumina, antimony oxide, magnesia, titanium oxide,
Examples include zinc oxide, silica, silica sand, quartz, oxides such as white carbon and diatomaceous earth, sulfides such as molybdenum disulfide, and metal powders. Examples of the plate-like filler include mica, glass flake, various metal foils, and the like. As the hollow filler, hollow glass beads or the like can be used.
When blending an inorganic filler, the blending amount is 2 to 100 parts by weight, based on 100 parts by weight of the branched polyacetal copolymer.
Preferably it is 2 to 50 parts by weight, more preferably 5 to 40 parts by weight. If the compounding amount is small, the reinforcing effect is small, and if it is too large, the fluidity is reduced and the surface properties are deteriorated, which causes practical problems.

The composite molded article of the present invention is characterized by using a branched polyacetal copolymer having a special molecular structure as described above, and the method of insert molding or outsert molding itself used for this is particularly preferable. It is not limited. That is, in the insert molding, a functional component made of a hard member such as a metal is placed in a mold, and the mold is filled with a molten resin and molded so that part or all of the functional component is wrapped with the resin. In the case of outsert molding, a substrate made of a hard member such as a metal is sandwiched between molds, and the mold is filled with a molten resin and the resin is formed on the substrate. By forming mechanisms and functional components such as pins, bushings, gears and cams and integrating them with a substrate or the like, the composite molded product of the present invention can be easily obtained.

As an application example of such a composite molded article of the present invention, a cold rolled steel, a zinc steel plate or an aluminum plate is used as a substrate,
Tape recorders, VTRs, timers, clocks chassis, printer side plates and keyboards in the OA field, electronic components made of thin phosphor bronze endless punched plates, and automotive parts in the OA field. High load components such as window regulators are included.

As in these examples, when the resin is integrated with a functional component or a board or the like made of a hard member such as a metal by insert molding or outsert molding, the resin is formed as the resin is cooled and solidified after molding. Internal strain, or thermal stress caused by a difference in the coefficient of thermal expansion between a metal or the like and a resin when a temperature change is applied to the integrated composite molded article, so that it is easy to cause creep destruction. By selecting the branched polyacetal as the resin material as described above, the durability against creep rupture can be improved without impairing the rigidity, slidability, fatigue resistance and the like of the polyacetal resin.

[0033]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. still,
The evaluation was performed by the following method. [Creep Destruction Test Using Insert Molded Product Model] A molded product (insert molded product model) having the shape shown in FIG. 1 was molded by an injection molding machine. The obtained molded product was heated to a temperature of 23.
After standing for 24 hours in a room adjusted to 50 ° C and 50% relative humidity, heat aging is performed at a constant temperature of 100 ° C, and the number of days until the resin part (mainly the weld on the opposite side of the gate) is destroyed is measured. did. [Heat Aging / Heat Shock Test of Outsert Molded Product] A molded product (outsert molded product model) having the shape shown in FIG. 2 was molded by an injection molding machine. After leaving the obtained molded product in a room adjusted to a temperature of 23 ° C and a humidity of 50%,
Heat aging treatment was performed at a constant temperature of 80 ° C for 100 hours, and the presence or absence of cracks and cracks due to creep rupture of the resin portion was examined.

Further, the molded article was subjected to a heat shock test at -30 ° C. to 80 ° C., and the presence or absence of cracks and cracks due to creep rupture of the resin portion was examined. The heat shock test is a test in which a molded article is heated at 80 ° C. for 1 hour, and then immediately transferred to an atmosphere of −30 ° C. and cooled for 1 hour. The test was performed. Examples 1 to 8 A paddle was provided using a continuous mixing reactor comprising a barrel having a jacket through which a heat (cooling) medium passes and a cross section having a shape in which two circles partially overlap with each other, and a rotary shaft with a paddle. While rotating the two rotating shafts marked with at 150 rpm,
Trioxane (a), monofunctional glycidyl compound (b),
The cyclic ether compound (c) was added at the ratio shown in Table 1, and methylal was continuously supplied as a molecular weight regulator. A homogeneous mixture mixed so as to have a conversion of 0.08% by weight was continuously added and supplied to perform bulk polymerization. The reaction product discharged from the polymerization machine was immediately passed through a crusher and added to an aqueous solution containing 0.05% by weight of triethylamine at 60 ° C. to deactivate the catalyst. Further, after separation, washing and drying, a crude polyacetal copolymer was obtained.

Next, the crude polyacetal copolymer 1
4 parts by weight of a 5% by weight aqueous solution of triethylamine to pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] was added and melt-kneaded at 210 ° C. with a twin-screw extruder to remove unstable parts. Furthermore,
Pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and 0.03 parts by weight of melamine.
15 parts by weight were added, and the mixture was melt-kneaded at 210 ° C. with a twin-screw extruder to obtain a pellet-shaped branched polyacetal resin composition.

Using these pellets, an injection molding machine
2 and the outsert molded article shown in FIG. 2 were molded and evaluated by the above method. Table 1 shows the evaluation results. Comparative Examples 1-2 As shown in Table 1, when the base resin was a polyacetal copolymer prepared without using the monofunctional glycidyl compound (b) and having no branched structure, pellets were prepared in the same manner as in the examples. A polyacetal in the form of was obtained, and an insert molded product shown in FIG. 1 and an outsert molded product shown in FIG. 2 were molded and evaluated by the above method. Table 1 shows the evaluation results.

[0037]

[Table 1]

B-1: butyl glycidyl ether b-2: 2-ethylhexyl glycidyl ether b-3: phenyl glycidyl ether b-4: o-phenylphenol glycidyl ether b-5: glycidyl stearate c-1: 1,3 -Dioxolan c-2: ethylene oxide

[0039]

According to the present invention, not only excellent mechanical properties, rigidity and slidability, but also improved creep rupture properties, thereby improving the creep rupture life and the heat shock life. An excellent composite molded product by insert molding or outsert molding can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an insert molded product used for a creep rupture test of the insert molded product.

FIG. 2 is a schematic view of an outsert molded product used in a heat aging / heat shock test of the outsert molded product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hard board (metal part) 2 Polyacetal copolymer resin 3 Runner part

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4F206 AA23E AB11 AC01 AD02 AD03 AH17 AH33 AK01 AM32 JA07 JB12 JE21 JF02 JL02 4J032 AA05 AA33 AA34 AA39 AB06 AB07 AB35 AC03 AC16 AC17 AC18 AD28 AD31 AD32 AD33 AD37 AD36 AD36 AD45 AD46 AD47 AD51 AE02 AE14 AF08

Claims (7)

[Claims] 1. A composite molded article in which a hard member and a resin are integrated by insert molding or outsert molding, wherein the resin has an oxymethylene group as a main repeating unit and a branch unit represented by the following general formula (I). A composite molded article characterized by using a branched polyacetal copolymer having the same. Embedded image (Wherein, m and n each represent an integer of 0 to 5, and m + n
Is 1 to 5. R represents a monovalent organic group having a molecular weight of 40 to 1,000. ) 2. The composite molded article according to claim 1, wherein R in the branch unit represented by the general formula (I) is selected from a monovalent organic group having an aromatic ring. 3. The branched polyacetal copolymer is composed of 100 parts by weight of trioxane (a), 0.001 to 10 parts by weight of a monofunctional glycidyl compound (b), and 0 to 20 parts by weight of a cyclic ether compound (c) copolymerizable with trioxane. The composite molded article according to claim 1 or 2, which is obtained by copolymerizing 4. A monofunctional glycidyl compound (b) comprising:
The composite molded article according to claim 3, which is a compound selected from the group consisting of a glycidyl ether compound and a glycidyl ester compound having a molecular weight of ~ 1000. 5. The monofunctional glycidyl compound (b) is selected from glycidyl ether compounds represented by the following general formulas (II), (III) and (IV).
The composite molded article according to the above. Embedded image (Wherein, R ¹ represents an alkyl group having 1 to 12 carbon atoms, a substituted alkyl group, an alkoxy group, an aryl group, a substituted aryl group,
Alternatively, n is an integer of 0 to 5;
Is 2 or more, R ¹ may be the same or different. ) (Wherein, R ² represents an alkylene group having 1 to 30 carbon atoms, a substituted alkylene group, a polyalkylene oxide glycol residue,
R ³ is an alkyl group having 1 to 12 carbon atoms, a substituted alkyl group,
An alkoxy group, an aryl group, a substituted aryl group, or a halogen, n is an integer of 0 to 5, and when n is 2 or more, R ³ may be the same or different. ) (Wherein, R ⁴ is an alkylene group having 1 to 30 carbon atoms, and n is 0)
Represents an integer of from 20 to 20, and R ⁵ represents an alkyl group having 1 to 30 carbon atoms, an alkenyl group or an alkynyl group having 2 to 20 carbon atoms. ) 6. The branched polyacetal copolymer which essentially comprises a cyclic ether compound (c) copolymerizable with trioxane and is copolymerized at a ratio of 0.1 to 20 parts by weight based on 100 parts by weight of trioxane. The composite molded article according to any one of claims 3 to 5. 7. The cyclic ether compound (c) copolymerizable with trioxane is ethylene oxide, 1,3-dioxolan, diethylene glycol formal and 1,4-
The composite molded article according to any one of claims 3 to 6, which is selected from butanediol formal.