JP2001011196A - Molding product and part composed of polyacetal copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molding product and a part composed of a polyacetal copolymer both having both a low secondary shrink characteristics of high degree and a low organic solvent gas permeability which have been difficult to attain. SOLUTION: The molding product is obtained by injection molding, extrusion molding or pressure forming a polyacetal copolymer which is a polyacetal copolymer having >=167 deg.C and <=171 deg.C melting point and has <=5,000 ppm low molecular weight polyacetal copolymer extracted with chloroform contained in the polyacetal copolymer. The part is obtained by injection molding, extrusion molding or pressure forming the polyacetal copolymer, or carrying out these molding methods and then by cutting process. Consequently, both a low secondary shrink characteristics of high degree and a low organic solvent gas permeability are simultaneously satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article of a polyacetal copolymer excellent in secondary shrinkage and organic solvent gas permeability.

[0002]

2. Description of the Related Art Polyacetal resins are easily crystallized, and molded products have excellent mechanical properties such as rigidity, heat resistance and creep resistance. Therefore, polymer materials widely used in electric and electronic equipment parts, automobile parts and the like. It is. However, since the polyacetal resin is a crystalline resin, it may be left for a long time after molding or exposed to a high temperature atmosphere, resulting in post-shrinkage,
That is, since the dimensional change occurs due to secondary shrinkage, there is a disadvantage that the application to precision parts is inevitably limited. As a method of improving the secondary shrinkability, a method of blending an inorganic filler is conventionally known. However, a polyacetal resin composition containing an inorganic filler has poor mechanical properties, particularly poor elongation and impact resistance, poor moldability, and low strength of a weld portion, and is difficult to use as a material for precision parts. There is a disadvantage that. As another method, for example, Japanese Patent Application Laid-Open No. 4-108848 discloses a proposal for achieving low secondary shrinkage by blending a polyoxymethylene homopolymer and a polyoxymethylene random copolymer at a predetermined ratio. It has been done. However, in this method, since a polyoxymethylene homopolymer having essentially poor heat stability is used, the heat stability of the obtained polymer is insufficient.

[0003] Further, since polyacetal resin is a crystalline resin having a very high degree of crystallinity, it can be generally said that an organic solvent gas is hardly permeated and is a resin excellent in organic solvent gas permeability. For example, butane, propane and the like are very excellent materials for a pressure vessel such as a gas lighter since they do not pass through a polyacetal resin. However, in recent years, energy saving has been called for in response to global environmental problems, and automobile parts, especially parts around automobile fuel, are also being reduced in weight by using resin, and gas such as gasoline and methanol, which are automobile fuels, are being used. Further improvements in permeability are required.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a molded article obtained by injection molding, extrusion molding or pressure molding of a polyacetal copolymer having excellent secondary shrinkage and organic solvent gas permeability, and the above polyacetal copolymer. Obtained by injection molding, extrusion molding, pressure molding, or cutting after these moldings, particularly O and typified by printers and copiers
Used for A equipment, VTR (Video Tape Recorder) and video movie, digital video camera, camera,
Used in camera and video equipment such as digital cameras, cassette players, DATs (Digital Audio
Tape), LD (Laser Disk), MD (Mini Disk), C
D (Compact Disk) [CD-ROM (Read Only Memor
y), CD-R (Recordable), CD-RW (Rewritabl)
e)], DVD (Digital Video Disk) [DVD-
ROM, DVD-R, DVD-RW, DVD-RAM
(Including Random Access Memory) and DVD-Audio], MFD (Micro Floppy Disk), MO (Magneto
Optical Disk), used for music, video or information equipment represented by navigation systems and mobile personal computers, etc. Used for communication equipment represented by mobile phones and facsimile machines, fuel pump modules, valves, gasoline tank flanges Parts around fuel such as door locks, door handles, window regulators, speaker grills, etc., seat belt peripheral parts such as through anchors and press buttons, combination switch parts, switches , Used in automotive interior and exterior parts such as clips, disposable cameras, toys, fasteners, chains, conveyors, buckles, sports equipment, vending machines, furniture,
Parts used for musical instruments and industrial parts represented by housing equipment, gears, cams, sliders, levers,
It provides mechanical parts such as arms, clutches, joints, shafts, bearings, key stems, key tops, shutters and reels, resin parts for outsert molding, chassis, trays and side plates.

[0005]

In view of this situation, the present inventors have conducted intensive studies and have found that low molecular weight components present in the polyacetal copolymer surprisingly surprisingly exist in the region where the melting point is 167 ° C or more and 171 ° C or less. The present inventors have found the fact that they greatly affect the secondary shrinkage and organic solvent gas permeability, and have completed the present invention. Although the detailed mechanism of this phenomenon is not clear, it is considered that the presence of the oligomer affects the crystallization temperature, the crystallization speed, and the like, and the crystallinity and the crystal structure are changed. It is not clear where the oligomer formation occurs, but it is thought that both the polymerization process and the process of removing the unstable portion of the copolymer molecule terminal are involved, and a specific amount of a specific cationic active initiator and a specific comonomer are used. When used and when a specific unstable terminal removing operation is performed, a target polyacetal copolymer having a small amount of oligomer can be obtained.

Specifically, a polyacetal copolymer excellent in secondary shrinkage and organic solvent gas permeability is obtained by copolymerizing trioxane and 1-3 dioxolane,
Melting point is 167 ° C or higher and 171 ° C or lower, and low molecular weight polyacetal extracted with chloroform is 5000p
pm or less. The polyacetal copolymer comprises trioxane and 1-3 dioxolane selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination complex of an organic compound containing an oxygen or sulfur atom and boron trifluoride. In the copolymerization using at least one of the obtained catalysts as a polymerization catalyst, the amount of the assembling catalyst used is 3 ppm or more and 30 ppm or less in terms of the weight of boron trifluoride per produced copolymer, and nitrogen is added to the polyacetal copolymer. 0.0 as minute
It is obtained by a production method characterized by performing a heat treatment at a resin temperature of from a melting point to 260 ° C. in the presence of a specific quaternary ammonium compound of from 5 ppm to 50 ppm.

Hereinafter, the present invention will be described in detail. The present inventors have found that, in a polyacetal copolymer having a melting point of 167 ° C. or more and 171 ° C. or less, for example, an oligomer present in the copolymer changes from a non-crystalline state to a crystalline state which occurs when cooled and solidified from a molten state as in injection molding. The rate of the state change at the time of transition to, that is, has a great influence on the crystallization rate, and, surprisingly, is greatly involved in the secondary shrinkage and the organic solvent gas permeability of the polyacetal copolymer molded article. I found that.

As a factor affecting the crystallization rate of a polyacetal copolymer, the amount of a comonomer contained in the copolymer is known, and the amount of the comonomer is also related to the melting point of the polyacetal copolymer. If the melting point of the polyacetal copolymer is less than 167 ° C., the influence of the comonomer amount on the crystallization rate becomes dominant,
The effect of the oligomer no longer appears. On the other hand, if the melting point exceeds 171 ° C., it is necessary to add a large amount of a heat stabilizer or the like in order to ensure sufficient thermal stability for practical use, and the melting point is lowered, which is not preferable. The melting point referred to in the present invention is defined as a melting point measured by using a differential calorimeter (DSC), once the temperature is raised to 200 ° C. and the sample is cooled to 100 ° C.
This is a value obtained as the peak temperature of heat generation in the process of raising the temperature at the rate of minutes.

The oligomer referred to in the present invention is a component extracted from the powder of the polyacetal copolymer by soxhlet extraction using chloroform for 24 hours to a soluble portion. According to proton NMR and mass spectrometry, the main component is Is a 4- to 16-mer formaldehyde having a molecular weight of 120.
About 480 compounds. The amount of oligomer allowed for the polyacetal copolymer molded article of the present invention to exhibit excellent secondary shrinkage and organic solvent gas permeability is 5%.
000 ppm or less, preferably 3000 ppm or less. Ideally, it is required that no oligomer is contained.However, in an industrially practicable production technology range, for example, in order to maintain the polymerization rate, it is impractical to extremely reduce the amount of the polymerization initiator. Yes, the content of 100 ppm or more must be allowed. An operation of extracting and removing oligomers from a product using a solvent is possible in a laboratory, but considering the labor involved, a decrease in the value of an industrial product cannot be avoided. In other words, 100 ppm or more and 50 ppm or less in a practically valuable polyacetal copolymer.
Oligomers of 00 ppm or less, preferably 3000 ppm or less are included.

When the analysis is carried out on a commercially available polyacetal resin material, various additives including an antioxidant are extracted simultaneously with the oligomer component. These additives are also considered to be involved in the reduction of the crystallization rate.For example, even if an antioxidant represented by hindered phenol is added in a range known to those skilled in the art, a large increase in secondary shrinkage, Alternatively, no decrease in organic solvent gas permeation performance is observed. This is due to the difference in melting point and compatibility with the polyacetal resin between the oligomer component and the additive, and they do not dissolve uniformly in the resin, or have a large molecular weight compared to the oligomer and an increase in secondary shrinkage, or This is considered to be due to the fact that it tends to be hardly involved in the reduction of the solvent gas permeation performance. These additive components and oligomer components are
By using gas chromatographic analysis and proton NMR for the extracted components, those skilled in the art can
Quantitative.

The polyacetal copolymer used in the polyacetal copolymer molded article of the present invention can be obtained by an operation in which a copolymer having a small amount of comonomer is synthesized in a laboratory, and an oligomer component is extracted and removed therefrom using a solvent. As already mentioned. However, the following contrivances are necessary to obtain the target product industrially. That is, the first point of the industrial production method of the present invention is selection of a comonomer used for copolymerization. Comonomers used in the polyacetal copolymer include ethylene oxide, propylene oxide,
1-3 dioxolane, 1-4 butanediol formal and the like are known, and those skilled in the art mainly select an appropriate one from an economic viewpoint. Certainly, in the category of polyacetal copolymer having a melting point of less than 167 ° C., the difference in the properties of the polymer due to the difference in comonomer type is not remarkable. For this reason, there are few proposals in the known art that the comonomer species should be specified and used. However, in the case of a copolymer having a melting point of 167 ° C. or higher and lower than 171 ° C., 1-3 dioxolane is used in a composition having a small oligomer amount. Effective for synthesis.

Second, the type and amount of the cationically active polymerization initiator used in the polymerization are important. In the present invention, at least one selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination complex of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom is used as a polymerization catalyst. It is effective to use as Preferred examples include boron trifluoride diethyl ether and boron trifluoride di-n-butyl ether. Generally, the amount of the polymerization catalyst used in the synthesis of polyacetal is determined in consideration of the polymerization rate and the molecular weight of the product. According to the present invention, the amount of oligomer is also related to the amount of catalyst, and it has been found that there is an appropriate range of the amount of catalyst used to obtain a copolymer having a small amount of oligomer. Specifically, the preferable amount of the polymerization catalyst used is 3 ppm or more and 30 p or more based on the weight of the produced copolymer.
pm or less. The amount of catalyst referred to here is not determined from the ratio of the reaction components prepared at the time of polymerization, but is analyzed by analyzing the actually obtained polyacetal copolymer and assuming that boron trifluoride is used as the polymerization catalyst. It is the value obtained by For example, when the polymerization operation is performed with an extremely small amount of the catalyst, the yield of the resin is reduced, and the amount of the catalyst per the produced resin is rather increased.

Further, if the amount of the polymerization catalyst used falls below or exceeds the appropriate range, it tends to be difficult to obtain a copolymer having less oligomers. This means that, besides the fluctuation of polymerization yield just mentioned, it is not possible to participate in the normal reaction due to lack of catalyst, or it is depolymerized by the presence of excess catalyst once incorporated into the polymer chain. It suspects that the formaldehyde formed may be involved in oligomer formation, but details are not clear. In addition, when the amount of the polymerization catalyst used falls below an appropriate range, there is a practically undesirable problem that the polymerization yield is reduced and the productivity is significantly reduced.

Third, it is also important to remove the unstable terminal after the completion of the polymerization. It is thought that the oligomer formation is reduced by performing this operation promptly, and it is preferable to use a specific quaternary ammonium compound as a catalyst in this operation. The quaternary ammonium compound used in the present invention is not particularly limited as long as it is represented by the following general formula (1), but [R ¹ R ² R ³ R ⁴ N ⁺ ] _n X ^-n (1) ( In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent an unsubstituted alkyl group or a substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; An aralkyl group in which an unsubstituted alkyl group or a substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or an aralkyl group having at least one aryl group having 6 to 20 carbon atoms having 1 to 30 carbon atoms. Represents a substituted alkyl group or an alkylaryl group substituted with a substituted alkyl group, wherein the unsubstituted alkyl group or the substituted alkyl group is linear, branched or cyclic, and the substituent of the substituted alkyl group is a halogen, a hydroxyl group, Aldehyde group, cal Hexyl group, an amino group, or an amide group. Also, the non-substituted alkyl group, an aryl group, an aralkyl group, an alkylaryl group may be a hydrogen atom substituted by a halogen .n the 1
Represents an integer of 3. X is a hydroxyl group, a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid other than hydrogen halide, an oxo acid,
It represents an acid residue of an inorganic thioacid or an organic thioacid having 1 to 20 carbon atoms. )

In the general formula (1), R ¹ , R ² , R ³ ,
And R ⁴ are each independently preferably an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms, and further, among them, R ¹ , R ² , R ³ , and R ^Four
In particular, those in which at least one of the above is a hydroxyethyl group are particularly preferred. Specifically, tetramethylammonium,
Tetraethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis (trimethylammonium), decamethylene-bis- (trimethylammonium), trimethyl-3-chloro- 2-hydroxypropyl ammonium, trimethyl (2-hydroxyethyl)
Ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxyethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium,
Triethylbenzylammonium, tripropylbenzylammonium, tri-n-butylbenzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, okdadecyltri ( Hydroxides such as 2-hydroxyethyl) ammonium and tetrakis (hydroxyethyl) ammonium; hydrochlorides such as hydrochloric acid, hydrobromic acid and hydrofluoric acid; sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, chloric acid and iodic acid Oxoacid salts such as silicic acid, perchloric acid, chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid and tripolyphosphoric acid; thioic acid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid , Isobutyric acid, pe Tan acid, caproic acid, caprylic acid, capric acid, benzoic acid, a carboxylic acid salt such as oxalic acid.

Among them, hydroxides (OH^-), Sulfuric acid (HS
O_Four ^-, SO_Four ^2-), Carbonic acid (HCO _Three ^-, CO_Three ^2-),
Boric acid (B (OH)_Four ^-), Carboxylic acid salts are preferred
No. Of the carboxylic acids, formic acid, acetic acid, and propionic acid are particularly
preferable. These quaternary ammonium compounds can be used alone
May be used, or two or more kinds may be used in combination.
Good. Further, in addition to the quaternary ammonium compound,
Known unstable terminal decomposition accelerators such as ammonia and
No problem even if amines such as liethylamine are used together.
I can't. The amount of the quaternary ammonium compound
The xymethylene copolymer is represented by the following formula (2).
To the amount of nitrogen derived from the quaternary ammonium compound
And preferably 0.05 to 50 ppm by weight. P × 14 / Q (2) [wherein P is a polyoxime of a quaternary ammonium compound.
Represents the concentration (wt ppm) relative to the styrene copolymer,
14 is the atomic weight of nitrogen and Q is quaternary ammonium
It represents the molecular weight of the compound. ]

When the amount of the quaternary ammonium compound added is 0.
If the amount is less than 05 ppm by weight, the rate of decomposition and removal of the unstable terminal portion is reduced. If the amount exceeds 50 ppm by weight, the color tone of the polyoxymethylene copolymer after the decomposition and removal of the unstable terminal portion is deteriorated. Preferred operating conditions are above the melting point of the composition and 260 ° C.
This is a heat treatment using an extruder, a kneader or the like at the following resin temperature. Formaldehyde generated by the decomposition is removed under reduced pressure. The method of addition is not particularly limited, and includes a method of adding it as an aqueous solution in the step of deactivating the polymerization catalyst, and a method of spraying the composition powder. Regardless of which addition method is used, it is only necessary that the composition be added in the step of heat-treating the composition, or if it is a variety that is injected into an extruder, or a filler or a pigment that is blended using an extruder or the like, The compound may be attached to a resin pellet, and an unstable terminal removal operation may be performed in a subsequent compounding step. The unstable terminal removal operation can be performed after deactivating the polymerization catalyst in the polyoxymethylene copolymer obtained by polymerization, or can be performed without deactivating the polymerization catalyst. It is. As a typical example of the deactivation operation of the polymerization catalyst, a method of neutralizing and deactivating the polymerization catalyst in a basic aqueous solution of an amine or the like can be given. It is also an effective method to carry out the operation of removing the unstable terminal after the polymerization catalyst is heated under an inert gas atmosphere at a temperature equal to or lower than the melting point without volatilizing the polymerization catalyst without deactivating the polymerization catalyst.

The preferred typical operation for obtaining the polyacetal copolymer used in the polyacetal copolymer molded article of the present invention has been proposed. Although this is an excellent method for industrially obtaining a target substance, it does not mean that the target substance cannot be obtained unless this method is strictly used. Even in the range of industrial manufacturing methods, for example, a method for thoroughly washing and removing a catalyst used for polymerization from a produced resin to reduce oligomers generated in a step after polymerization, and known instability such as sodium hydroxide, ammonia water, and triethylamine. There is a method of using a relatively large amount of a terminal removing catalyst and performing heat treatment in the presence of a high concentration of a decomposition aid. However, the polyacetal copolymer may be colored or the productivity may be reduced.
Problems often remain in exchange for the effect of improving the secondary shrinkage or the organic solvent gas permeability.

Further, it is optional to add known additives, heat stabilizers, organic / inorganic fillers and the like to the polyacetal copolymer used in the molded article of the polyacetal copolymer of the present invention within a range not to impair the gist of the invention. The polyacetal copolymer used in the polyacetal copolymer molded article of the present invention can be mixed with an appropriate additive depending on the application to obtain a practically usable polyacetal resin composition having excellent thermal stability and properties. Preferable examples are (A) an antioxidant, a polymer or compound containing formaldehyde-reactive nitrogen, a formic acid scavenger, and weather resistance (light) based on 100 parts by weight of the polyacetal copolymer.
0.1 to 1 at least one of a stabilizer and a release (lubricating) agent
A polyacetal resin composition comprising 0 parts by weight, (B) at least one of a reinforcing agent, a conductive material, a thermoplastic resin, and a thermoplastic elastomer, from 0 to 60 parts by weight, and (C) 0 to 5 parts by weight of a pigment. Can be mentioned.

As the antioxidant, a hindered phenol-based antioxidant is preferable. Specifically, for example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4 ′)
-Hydroxyphenyl) -propionate, n-octadecyl-3- (3'-methyl-5'-t-butyl-4 '
-Hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- [3- (3, 5-di-t-butyl-
4-hydroxyphenyl) -propionate], 1,4
-Butanediol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate],
Triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ', 5'-
Di-t-butyl-4'-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3-t-
Butyl-4-hydroxy-5-methylphenyl) propionyloxy {-1,1-dimethylethyl] 2,4
8,10-tetraoxaspiro (5,5) undecane,
N, N'-bis-3- (3 ', 5'-di-t-butyl-
4'-hydroxyphenyl) propionylhexamethylenediamine, N, N'-tetramethylene-bis-3-
(3'-methyl-5'-t-butyl-4'-hydroxyphenol) propionyldiamine, N, N'-bis-
[3- (3,5-Di-t-butyl-4-hydroxyphenol) propionyl] hydrazine, N-salicyloyl-N'-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4- Triazole, N, N'-
Bis [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] oxyamide; Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and tetrakis [methylene-3- (3 ′, 5′-di-t-butyl) -4 '
-Hydroxyphenyl) propionate] methane. One of these antioxidants may be used,
A combination of more than two types may be used.

Examples of polymers or compounds containing formaldehyde-reactive nitrogen include nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6
And polyamide resins such as nylon 12 and nylon 12, and polymers thereof, for example, nylon 6 / 6-6 / 6-10 and nylon 6 / 6-12. Further, as a copolymer of acrylamide and its derivatives, acrylamide and its derivatives and other vinyl monomers, poly-β obtained by polymerizing acrylamide and its derivatives and other vinyl monomers in the presence of a metal alcoholate is used. −
Alanine copolymers can be mentioned. One of these polymers containing a formaldehyde-reactive nitrogen atom may be used alone, or two or more thereof may be used in combination.

Examples of compounds containing a formaldehyde-reactive nitrogen atom having an amino substituent include 2,4
-Diamino-sym-triazine, 2,4,6-triamino-sym-triazine, N-butylmelamine, N-
Phenylmelamine, N, N-diphenylmelamine, N,
N-diallylmelamine, N, N ', N "-triphenylmelamine, melem, melon, melam, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6) -Methyl-sym-triazine), 2,4-diamino-6-butyl-sym-triazine, 2,4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4
-Diamino-6-chloro-sym-triazine, 2,4
-Diamino-6-mercapto-sym-triazine,
2,4-dioxy-6-amino-sym-triazine,
2-oxy-4,6-diamino-sym-triazine,
N, N, N ', N'-tetracyanoethylbenzobuamine, succinoguanamine, ethylenedimelamine, triguanamine, melamine cyanurate, ethylenedimeramine cyanurate, triguanamine cyanurate, ammeline, acetoguanamine and the like. . These triazine derivatives may be used alone or in a combination of two or more.

Examples of formic acid scavengers include the above-mentioned amino-substituted triazines and polycondensates of amino-substituted triazines with formaldehyde, such as melamine-formaldehyde polycondensates. Other formic acid supplements include:
Alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylates or alkoxides may be mentioned. For example, hydroxides such as sodium, potassium, magnesium, calcium and barium, and carbonates, phosphates, silicates, borates and carboxylates of the above metals. As the carboxylic acid, a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms is preferable, and these carboxylic acids may be substituted with a hydroxyl group. Aliphatic carboxylic acids include capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachiic acid, behenic acid, ligglyceric acid,
Cerotic acid, heptacosanoic acid, montanic acid, melicic acid, lacceric acid, undecylenic acid, oleic acid, elaidic acid, setreic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, Stearolic acid, 12-hydroxydodecanoic acid, 3-hydroxydecanoic acid, 16-hydroxyhexadecanoic acid, 10-hydroxyhexadecanoic acid, 12-
Hydroxyoctadecanoic acid, 10-hydroxy-8-octadecanoic acid, dl-erythro-9.10-dihydroxyoctadecanoic acid and the like can be mentioned. As a specific example,
Calcium dimyristate, calcium dipalmitate, calcium distearate, calcium (myristate-palmitate) calcium, (myristate-stearate) calcium, (palmitate-stearate) calcium, with dipalmitin being particularly preferred. Calcium acid and calcium distearate. In the present invention, two or more formic acid supplements may be added simultaneously, and there is no limitation.

The weather (light) stabilizer referred to in the present invention is preferably one or more selected from benzotriazole-based, oxalic anilide-based ultraviolet absorbers and hindered amine-based light stabilizers. Examples of the benzotriazole-based ultraviolet absorber include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl-phenyl) ) Benzotriazole, 2- [2'-hydroxy-3 ',
5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-3 ′,
5′-di-t-amylphenyl] benzotriazole,
2- (2′-hydroxy-3 ′, 5′-di-isoamyl-phenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl]- 2H-benzotriazole, 2-
(2′-hydroxy-4′-octoxyphenyl) benzotriazole and the like. Examples of oxalic acid alinide UV absorbers include 2-ethoxy-2'-ethyloxalic acid bisanilide and 2-ethoxy-5-t.
-Butyl-2'-ethyloxalic acid bisanilide, 2-ethoxy-3'-dodecyloxalic acid bisanilide and the like. These ultraviolet absorbers may be used alone or in combination of two or more.

Examples of hindered amine light stabilizers include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-
Tetramethylpiperidine, 4-acryloyloxy-
2,2,6,6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4- Methoxy-2,2,6,6-
Tetramethylpiperidine, 4-stearyloxy-2,
2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2, 2,6,6-tetramethylpiperidine, 4- (ethylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4-
(Cyclohexylcarbamoyloxy) -2,2,6
6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) -carbonate, bis (2 2,6,6-tetramethyl-4-piperidyl) -oxalate, bis (2
2,6,6-tetramethyl-4-piperidyl) -malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis (2,2,6,6-tetramethyl-4) -Piperidyl) -adipate, bis (2,
2,6,6-tetramethyl-4-piperidyl) -terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -ethane, α, α′-bis (2 2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyltolylen-2,4-dicarbamate, bis (2,2 , 6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,5-tri Carboxylate,
Tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate,
1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} butyl] -4-
[3- (3,5-Di-t-butyl-4-hydroxyphenyl) propionyloxy] 2,2,6,6-tetramethylpiperidine, 1,2,3,4-butanetetracarboxylic acid and 1,2 , 2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,
9- [2,4,8,10-tetraoxaspiro (5,
5) Undecane] condensate with diethanol. The hindered amine light stabilizers may be used alone or in combination of two or more.

Among them, preferred weathering agents are 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole and 2- (2'-hydroxy-3', 5 ' -Di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-
Di-t-amylphenyl] benzotriazole, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis- (N-methyl-2,2,6,6
-Tetramethyl-4-piperidinyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidinyl)
Sebacate, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9-
This is a condensate with [2,4,8,10-tetraoxaspiro (5,5) undecane] diethanol.

As the release agent, alcohols, fatty acids and their fatty acid esters, polyoxyalkylene glycols, olefin compounds having an average degree of polymerization of 10 to 500, and silicones are preferably used. Examples of the reinforcing agent include inorganic fillers, glass fibers, glass beads, and carbon fibers. In addition, examples of the conductive material include conductive carbon black, metal powder, and fiber. Examples of the thermoplastic resin include a polyolefin resin, an acrylic resin, a styrene resin, a polycarbonate resin, and an uncured epoxy resin. In addition, these modified products are also included. Typical examples of the thermoplastic elastomer include a polyurethane elastomer, a polyester elastomer, a polystyrene elastomer, and a polyamide elastomer.

The pigment used in the present invention is used in the range of 0 to 5 parts by weight. If it exceeds 5 parts by weight, the thermal stability decreases, which is not preferred. Examples of the pigment include an inorganic pigment and an organic pigment. The inorganic pigment is generally used for coloring a resin, and includes, for example, zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, and the like. The organic pigment is a pigment of condensed azo type, inone type, flotocyanine type, monoazo type or the like. Since the polyacetal copolymer molded article of the present invention has little secondary shrinkage, it can be suitably used for various parts requiring dimensional accuracy. Also, since it has excellent organic solvent gas permeability, it can be suitably used for applications requiring material properties such as low organic solvent gas permeability, for example, automotive fuel parts.

Further, it is used for injection molding, extrusion molding, pressure molding, or OA equipment typified by printers and copiers obtained by cutting after molding.
R (Video Tape Recorder) and used in camera / video equipment such as video movies, digital video cameras, cameras, digital cameras, cassette players, DAT (Digital Tape Recorder), LD (Lase
r Disk), MD (MiniDisk), CD (Compact Disk)
[CD-ROM (Read Only Memory), CD-R (Reco
rdable), including CD-RW (Rewritable)], DVD
(Digital VideoDisk) [DVD-ROM, DVD-
R, DVD-RW, DVD-RAM (Random Access Memo)
ry), DVD-Audio), MFD (Micro F
loppy Disc), MO (Magneto Optical Disk), navigation systems, mobile personal computers and other music, video or information equipment,
Used in communication equipment such as mobile phones and facsimile machines, and fuel-related parts such as fuel pump modules, valves, gasoline tank flanges, and door locks, door handles, window regulators, and speaker grills. Used for car interior and exterior parts such as door parts, seat belt peripheral parts such as through anchors and press buttons, combination switch parts, switches, clips, etc., and disposable cameras,
Parts used for toys, fasteners, chains, conveyors, buckles, sports equipment, vending machines, furniture, musical instruments, and industrial parts represented by housing equipment, gears, cams, sliders, levers, arms, clutches Provide mechanical parts such as joints, shafts, bearings, key stems, key tops, shutters, reels, outsert molded resin parts, chassis, trays and side plates.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, according to Examples and Comparative Examples,
The present invention will be described more specifically, but the present invention is not limited thereto. The terms and measuring methods in the examples and comparative examples are as follows. <Melting point (° C)> Differential calorimeter (PerkinElmer, D
Using SC-2C), the temperature of the sample once heated to 200 ° C. and melted is cooled to 100 ° C., and the peak top temperature of the exothermic peak generated in the process of raising the temperature again at a rate of 2.5 ° C./min is calculated as Melting point. <Crystallization rate (second)> A 5 mg pellet was hot-pressed into a film, and was cooled from room temperature to 20% using a DSC measurement device (Perkin Elmer, DSC-2C).
The temperature was raised to 0 ° C., and the temperature was maintained for 2 minutes to remove thermal distortion, cooled to 150 ° C. at a rate of 80 ° C./min, maintained at this temperature, and observed the crystallization exothermic peak counted from the time at which the temperature reached 150 ° C. The time to the completion was determined and used as an index.

<Boron trifluoride concentration (ppm)> After the polyacetal copolymer is thermally decomposed with 1N-HCl,
The fluorine concentration in the polyacetal copolymer was measured using a fluorine ion electrode (manufactured by HORIBA), and this was converted to a boron trifluoride concentration. <Amount of Oligomer (ppm)> The polyacetal copolymer was freeze-pulverized and subjected to Soxhlet extraction using 10 g of 150 ml of chloroform for 24 hours, and the weight of the extract was measured. And the amount of oligomer was determined.

<Flexural modulus (kg / cm ² )> Using an IS-80A injection molding machine manufactured by Toshiba Corporation, cylinder temperature 200 ° C., injection pressure 60 kgf / cm ² , injection time 1
A test piece was prepared for 5 seconds, a cooling time of 25 seconds, and a mold temperature of 70 ° C., and measured according to ASTM-D-790. <Formaldehyde gas generation rate (ppm / min)>
In a nitrogen stream, formaldehyde gas generated from the polyoxymethylene copolymer at 230 ° C. for 90 minutes is absorbed in water, and then titrated and measured. The measured total formaldehyde amount was divided by 90 minutes to calculate the average formaldehyde gas generation rate per minute (ppm / min). The lower the formaldehyde gas generation rate, the better the thermal stability.

<Secondary Shrinkage (%)> A test piece was prepared under exactly the same injection molding machine and injection conditions as in the preparation of the test piece for measuring the flexural modulus. After molding is completed, it is placed in an environment of 23 ° C and 50% humidity.
After leaving for 8 hours, the dimension in the flow direction was D ₁ (mm). After completion of molding, the substrate was left for 72 hours in an environment of 23 ° C. and 50% humidity, heated at 80 ° C. for 5 hours, and then heated at 23 ° C. The secondary shrinkage (%) was determined according to the following equation, where D ₂ (mm) was the dimension in the flow direction after standing for 48 hours. Secondary shrinkage (%) = (D ₁ −D ₂ ) / mold size × 100 However, the smaller the mold size is 130 mm and the thickness 3 mm, the better the secondary shrinkage.

<Gas permeability (g · mm / day / m ² )
> Injection molding machine that is exactly the same as the test piece for flexural modulus measurement,
A test piece having a thickness of 2 mm was prepared under the injection conditions. The test piece is covered with a stainless steel cylindrical container having a diameter of 38 mm and containing an organic solvent (gasoline, gasoline having a methanol concentration of 15% by volume, and methanol). A packing was inserted between the test piece and the cylindrical container so that the organic solvent gas did not decrease except for the permeation of the test piece. After the sample prepared as described above was allowed to stand at 60 ° C. for 750 hours, the reduction amount (g) of the organic solvent was measured, and the amount of gas permeating a test piece having an area of 1 m ² and a thickness of 1 mm per day was calculated. The gas permeability (g · mm / day / m ² ) was determined. The smaller the value, the better the gas permeability. <%, Ppm> All parts are by weight unless otherwise specified.

[0035]

Example 1 A twin-screw paddle type continuous polymerization machine equipped with a jacket through which a heat medium can pass was adjusted to 80 ° C.
Trioxane of Hr, 148 g / Hr of 1,3-dioxolane as a comonomer (0.015 mol per mol of trioxane), and 7.1 g / Hr of methylal as a molecular weight regulator (0.7 × 0.7 mol / mol of trioxane)
10 ^-3 mol) were added continuously. Further, as a polymerization catalyst, a solution of 1% by weight of boron trifluoride di-n-butyl etherate in cyclohexane such that boron trifluoride is 1.5 × 10 ⁻⁵ mol per 1 mol of trioxane 39. 6 g / Hr was added continuously to carry out polymerization. The polyacetal copolymer discharged from the mixer was charged into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst. After filtering the deactivated polyacetal copolymer by a centrifuge, the filtered polyacetal copolymer 1
To 100 parts by weight, 1 part by weight of an aqueous solution containing choline hydroxide formate (trimethyl-2-hydroxyethylammonium formate) as a quaternary ammonium compound was added, mixed uniformly, and dried at 120 ° C. did.

The amount of the added choline hydroxide was 20 ppm in terms of the amount of nitrogen. The amount of the added choline hydroxide was adjusted by adjusting the concentration of the added choline hydroxide in the aqueous solution containing the added choline hydroxide. To 100 parts by weight of the dried polyacetal copolymer, 0.3 parts by weight of 2,2'-methylenebis- (4-methyl-t-butylphenol) as an antioxidant was added, and a vented twin-screw extruder was used. Supplied. 0.5 parts by weight of water was added to 100 parts by weight of the molten polyacetal copolymer in the extruder, and the unstable terminal portion was decomposed at a set temperature of the extruder of 200 ° C. and a residence time of 5 minutes in the extruder. The oxymethylene copolymer decomposed at the unstable terminal was devolatilized under a condition of a vent vacuum of 20 Torr, extruded as a strand from an extruder die, and pelletized. Further, 0.15 parts by weight of calcium stearate and 0.05 parts by weight of nylon 66 were mixed with 100 parts by weight of the pellets and melt-kneaded with a vented single-screw extruder to obtain final polyacetal copolymer pellets. . Table 1 summarizes the melting point, crystallization time, boron trifluoride concentration, oligomer amount, flexural modulus, formaldehyde gas generation rate, secondary shrinkage, and gas permeability of the obtained polyacetal copolymer.

[0037]

Examples 2 to 4 Comparative Examples 1 to 4 and Comparative Example 5 Example 2
In Comparative Examples 1-4 and Comparative Examples 1-4, experiments similar to those in Example 1 were conducted by changing the type and amount of the comonomer used in the polymerization and the amount of the polymerization catalyst used. The results are shown in Table 1 together with Example 1. Comparative Example 5 in Table 1 shows the measurement results of the flexural modulus, the formaldehyde gas generation rate, the secondary shrinkage, and the gas permeability of the tenac homopolymer (5010).
It is clear that a composition having a melting point of 167 ° C. or more and 171 ° C. or less and an oligomer amount of 3000 ppm or less has excellent rigidity, extremely excellent thermal stability, low secondary shrinkage, and low gas permeability. It is.

[0038]

Examples 5 to 7 In Examples 5 and 6, the same experiment as in Example 1 was conducted except that the amount of choline hydroxide used was changed. In Example 7, an experiment similar to Example 1 was performed using triethylcholine hydroxide (triethyl-2-hydroxyethylammonium formate) instead of choline hydroxide formate. The melting point, crystallization time, boron trifluoride concentration, oligomer amount, flexural modulus, formaldehyde gas generation rate, secondary shrinkage, and gas permeability of the obtained polyacetal copolymer are shown in Table 2.

[0039]

Comparative Example 6 Except that the unstable terminal portion was decomposed by the following method without adding choline hydroxide formate,
The same operation as in Example 1 was performed. The results are shown in Example 5.
The results are shown in Table 2 together with Tables 1 to 7. (Method of decomposing and removing unstable parts) For 100 parts by weight of the dried polyacetal copolymer, as an antioxidant,
0.3 parts by weight of 2,2'-methylenebis- (4-methyl-t-butylphenol) was added and fed to a vented twin-screw extruder, and 100 parts by weight of a molten polyacetal copolymer in the extruder. Then, 3 parts by weight of a 20% aqueous solution of triethylamine was added thereto, and the unstable terminal portion was decomposed at a set temperature of the extruder of 200 ° C. and a residence time of 5 minutes in the extruder. It can be seen that, unless a quaternary ammonium compound is added to decompose and remove unstable portions, the amount of oligomers increases and rigidity decreases. In addition, thermal stability is poor. Furthermore, the secondary shrinkage and the gas permeability are also deteriorated.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

According to the present invention, the melting point is 167 ° C. or more and 171 ° C.
The following polyacetal copolymer, and the low molecular weight polyacetal copolymer extracted by chloroform contained in the polyacetal copolymer is 500
Molded articles and injection molded articles obtained by injection molding or extrusion molding of 0 ppm or less polyacetal copolymer,
Parts obtained by extrusion, cutting, or cutting after injection molding or extrusion molding have excellent rigidity, low secondary shrinkage,
It has low organic solvent gas permeability. According to the present invention, there are provided molded articles and parts made of a polyacetal copolymer having high low secondary shrinkage and low organic solvent gas permeability, which have been hitherto difficult.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 33/02 305 G11B 33/02 305Z 5C022 H04N 5/225 H04N 5/225 Z F term (reference) 3J011 DA02 SC02 3J030 BC01 BC08 3J070 AA01 AA41 BA77 4F071 AA40 AA84 AA89 AF08 AF20 AF54 AH03 AH07 AH12 AH17 AH18 BB03 BB05 BB06 BC00 4J002 CB001 CB002 FD040 FD050 FD070 FD090 FD160 FD200 GL00 GM00 A0205

Claims (11)

[Claims] Injection molding and extrusion molding of a polyacetal copolymer having a melting point of 167 ° C. or more and 171 ° C. or less and a low molecular weight polyacetal copolymer extracted by chloroform contained in the polyacetal copolymer is 5000 ppm or less. Or a molded article obtained by pressure molding. 2. A part obtained by subjecting the polyacetal copolymer of claim 1 to injection molding, extrusion molding, pressure molding, or cutting after molding. 3. The component according to claim 2, wherein the component is at least one selected from the group consisting of a mechanical component, a resin component of outsert molding, a chassis, a tray, and a side plate.
Parts described. 4. The mechanism component includes a gear, a cam, a slider,
4. The component according to claim 2, wherein the component is at least one selected from the group consisting of a lever, an arm, a clutch, a joint, a shaft, a bearing, a key stem, a key top, a shutter, and a reel. 5. The component according to claim 2, which is used for OA equipment such as a printer and a copying machine. 6. The component according to claim 2, wherein the component is used for a VTR and a video camera such as a video movie, a digital video camera, a camera, and a digital camera. 7. A cassette player, DAT, LD, M
D, CD (including CD-ROM, CD-R, CD-RW),
DVD (including DVD-ROM, DVD-R, DVD-R
W, DVD-RAM, DVD-Audio), MFD,
The component according to any one of claims 2 to 4, which is used for music, video, or information equipment typified by an MO, a navigation system, and a mobile personal computer. 8. The component according to claim 2, which is used for a communication device typified by a cellular phone, a facsimile, and the like. 9. Use according to claim 2 for interior and exterior parts of automobiles.
4. The component according to any one of 4. 10. Automotive interior / exterior parts include fuel pump parts, valves, fuel tank parts such as gasoline tank flanges, door lock parts, door handles, window regulators, speaker grilles, etc. The component according to claim 9, wherein the component is at least one of a seat belt peripheral component represented by an anchor press button, a combination switch component, a switch, and a clip. 11. A disposable camera, a toy, a fastener,
The component according to any one of claims 2 to 4, which is used for an industrial component such as a chain, a conveyor, a buckle, a sporting goods, a vending machine, furniture, a musical instrument, and a housing equipment.