JPS6363741A - Oxymethylene copolymer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in heat stability, by mixing a specified polymer with an additive, a hindered phenolic antioxidant and a formaldehyde absorbent. CONSTITUTION:Trioxane and 0.1-10mol% cyclic ether (e.g., ethylene oxide) are bulk-polymerized together at 60-115 deg.C in the presence of at least one polymerization catalyst selected from among BF3 (hydrate) and coordination compounds of BF3 with O- or S-containing organic compounds (e.g., BF3 diethyl etherate), and the catalyst is deactivated by the addition of a hindered amine to obtain a polymer (A). Component A is mixed with 0.001-5wt% at least one additive (B) selected from among the hydroxides, inorganic oxides, organic acid salts and alkoxides of alkali (alkaline earth) metals, 0.001-5wt% hindered phenolic antioxidant (C) [e.g., 2,2-methylene-bis(4-methyl-6-tert-butylphenol)] and 0.001-5wt% reagent (C) which absorbs formaldehyde by reacting with it (e.g., guanamine).

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Section> The present invention relates to oxymethylene copolymer compositions endowed with thermal stability.

<Prior Art> It is known to obtain oquinomethylene homopolymers or copolymers by bulk polymerizing trioxane alone or trioxane and a cyclic ether in the presence of a catalyst, as disclosed in, for example, Japanese Patent Publication No. 44-5234. The obtained polymer is thermally unstable as it is, so in the case of a homopolymer, it is stabilized by blocking the ends by esterification, etc., and in the case of a copolymer, by decomposing and removing unstable ends. Prior to this, it is necessary to stop the reaction by deactivating the catalyst.

In other words, if the catalyst remaining in the oxymethylene homopolymer or copolymer obtained by polymerizing trioxane or the like is not deactivated, it will gradually depolymerize and cause a significant decrease in molecular weight. , it becomes extremely unstable thermally.

Regarding deactivation of boron trifluoride polymerization catalysts, US Pat. No. 2,989,509 proposes the use of aliphatic amines and heterocyclic amines. If these are removed by washing, the polymer is stabilized and no decrease in molecular weight is observed even if it is stored for a long period of time.

However, even if the catalyst is deactivated with a common amine compound, if the catalyst is not removed from the polymer by washing, depolymerization will still occur when the polymer is melted or dissolved, resulting in a decrease in molecular weight. Therefore, after deactivating the catalyst with an amine, it was essential to remove the catalyst from the polymer by a thorough washing operation. For example, the special public service 39-807
Methods for terminal stabilization of oxymethylene copolymers are described in Publication No. 1 and Japanese Patent Publication No. 43-1875, but in these methods, the polymerization catalyst is deactivated with an amine prior to terminal stabilization, and Removed by washing. Recently, trivalent phosphorus compounds have been discovered as catalyst deactivators that do not require washing or removal, and are described in Japanese Patent Publication No. 55-42085. However, in order to produce an oxymethylene copolymer with even higher thermal stability, it is essential to deactivate the catalyst, decompose unstable terminals, and add a stabilizer. A wide variety of stabilizer formulations have been known,
For example, Japanese Patent Publication No. 34-5440 describes stabilization by kneading polyamide and hindered phenol.

<Problems to be Solved by the Invention> Although thermal stability is certainly increased by the above-mentioned mixing of stabilizers, if the stabilizer remains in a molten state for a long time during molding, etc., it decomposes and foams, resulting in mold deposits. , was still not satisfactory. Furthermore, if washing and removal of the catalyst is omitted in the catalyst deactivation process using an amine, the thermal stability of the polymer will be extremely low no matter what kind of stabilizer is kneaded, it will not be able to withstand melt molding, etc. Thermal stability is insufficient even when using a phosphorus compound of

The present inventors have conducted intensive studies to obtain an oxymethylene copolymer composition having extremely excellent thermal stability, and as a result, have discovered the present invention.

Means for Solving the Problems> That is, the present invention combines a mixture of trioxane and a cyclic ether with boron trifluoride, boron trifluoride hydrate, and an organic compound containing boron trifluoride and an oxygen atom or a sulfur atom. After bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of coordination compounds, the polymer is subjected to hydroxylation of alkali metals and alkaline earth metals. An oxymethylene copolymer composition prepared by adding and mixing one or more selected from compounds, inorganic acid salts, organic acid salts, and alkoxides, a hindered phenolic antioxidant, and an agent capable of reacting with formaldehyde and absorbing formaldehyde. It is a thing.

The cyclic ether used in this paper is of the following general formula (A
It means a compound represented by 3.

y2-c-.

II (AJ Ys C(X)m (in the formula, Y and ~Y4 are hydrogen atoms, carbon atoms 1 to 6
represents an alkyl group and a halogen-substituted alkyl group having 1 to 6 carbon atoms, which may be the same or different.

Further, X represents a methylene or oxymethylene group, which may be substituted with an alkyl group or a halogen-substituted alkyl group, and m represents an integer of O to 3. Alternatively, X is -(CH
2) I) -0-CH2- or H-0-CH2-(CH2
)I)-O-CH2-, in which case m=
1, p is an integer of 1 to 3) Among the cyclic ethers or cyclic acecules represented by the above general formula,
Preferred compounds include ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-dioxane, 1,3-dioxolane, 1,3,5-trioxepane, 1,3,6-triosocane, and ebichlor. Examples include hydrin.

The copolymerization amount of the cyclic ether of the present invention needs to be in the range of 0.1 to 10 mol%, particularly preferably 0.2 to 6 mol%, based on the trioxane. In addition, the thermal stability of the composition is low, and if it is more than 10 mol %, it lowers the melting point and crystallinity of the resulting composition, resulting in poor mechanical strength and moldability, which is not preferable.

In the polymerization catalyst of the present invention, one or more compounds selected from the group of heptaboron trifluoride, boron trifluoride hydrate, and coordination compounds of boron trifluoride and organic compounds having oxygen or sulfur atoms are It can be used in solid, liquid or solution form in a suitable organic solvent.

Examples of the organic compound having an oxygen or sulfur atom that forms a coordination compound with boron trifluoride include alcohol, ether, phenol, sulfide, and the like.

Among these catalysts, coordination compounds of boron trifluoride are particularly preferred, and boron trifluoride/diethyl etherate and boron trifluoride/dibutyl etherate are particularly preferably used.

Examples of the solvent for the polymerization catalyst in the present invention include aromatic hydrocarbons such as benozene, toluene, and xyleno, aliphatic hydrocarbons such as n-hexane, n-heptano, and cyclohexane, alcohols such as methanol and ethanol, chloroform, Unahalogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, acetone, ketones such as methyl ethyl ketone are used.

The amount of polymerization catalyst added is 5 to 1 mole of trioxane.
The range is from x l O-' to lXl0' mol, particularly preferably from I X I O-5 to I X I O-2
It is in the molar range.

Various apparatuses are known for polymerizing trioxane alone or trioxane and a cyclic ether in bulk, but the bulk polymerization used in the present invention is not particularly limited by the apparatus, and the polymerization amount is 10% by weight or less based on trioxane. Therefore, it can also be applied to polymerization reactions conducted in the presence of organic solvents such as cyclohexane.

In bulk polymerization, since rapid solidification and heat generation occur during polymerization, an apparatus having strong stirring ability and capable of controlling the reaction temperature is particularly preferably used.

The bulk polymerization apparatus of the present invention having such performance uses a cylindrical barrel as the reaction zone of the kneader 1 having a Nogma-type stirring blade, and is equipped with a coaxial screw having a large number of interrupted threads in the barrel. , a mixer that operates so that this interruption meshes with teeth protruding from the inner surface of the barrel, and two conventional screw extruders that have a pair of mutually meshing parallel screws in a long case with a jacket for heating or cooling. A self-cleaning mixer that has a large number of paddles on a horizontal stirring shaft, and when the shafts are rotated simultaneously in the same direction, the mixer rotates while maintaining a slight clearance between each paddle surface and the inner surface of the case. etc. can be mentioned.

In addition, in bulk polymerization, strong stirring capacity is required because the polymerization solidifies rapidly in the early stage of the polymerization reaction. It may be divided into stages.

The bulk polymerization reaction temperature is preferably in the temperature range from near the melting point to near the boiling point of trioxane, that is, in the range of 60 to 113°C, particularly preferably in the range of 60 to 90°C.

In the early stages of polymerization, the temperature inside the polymerization reactor tends to rise due to reaction heat and frictional heat from solidification, so it is desirable to control the reaction temperature by passing cooling water through the jacket, etc. .

Typical hindered amine compounds that deactivate the boron trifluoride catalyst used in the present invention and stop the polymerization reaction include the following compounds.

aTc=CH,C0O- qHCOO- Jigoji1 Among these hindered amino compounds, tertiary amine type hindered amino compounds are particularly preferably used because the obtained polymer has excellent color tone.

Regarding the amount of the hindered amino compound added, it is preferable that there be at least the same number of nitrogen atoms having hindodamine as the number of boron atoms in the boron trifluoride catalyst of the polymerization catalyst used.

Although the catalyst deactivation effect can be seen even if the number of nitrogen atoms is less than the number of boron atoms, the heat resistance stability of the obtained polymer will decrease slightly, so the amount added should be adjusted according to the desired degree of heat resistance stability. There is a need.

Specific examples of the hydroxides, inorganic acid salts, organic acid salts, and alkoxides of alkali metals and alkaline earth metals used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, Calcium hydroxide,
Barium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, sodium phosphate, sodium borate,
Sodium acetate, magnonium acetate, sodium benzoate, sodium terephthalate, sodium methoxide,
Potassium nitoxide, hepthorium ethoxide, potassium nitoxide, magnonium ethoxide, sodium isopropoxychloride, sodium phenoquinide, n-butyllithium, and the like can be mentioned.

The amount of the alkali metal, alkaline earth metal hydroxide, inorganic acid salt, organic acid salt, and alkoxide used in the present invention is 0001 to 5 times 1 based on the oxymethylene copolymer.
%, preferably 0.05 to 3% by weight. 0.001
If it is less than 5% by weight, the thermal stability of the resulting composition will be low, and if it is more than 5% by weight, mechanical stability and hydrolysis resistance will be reduced, which is not preferable.

Examples of the hinodade phenol oxidation inhibitor used in the present invention include compounds represented by the following general formula.

(t: tcoL In the formula, X!, X2, and X3 are an alkyl group, a halogenated alkyl group, an alkokene group, a thioalkyl group, a halogenated alkokino group, an aryl group, an arylophne group, a substituted aryl group, a substituted aryloquino group) 2,2-methylene-bis(4
-Methyl-5-tert-butylphenol), triethyleneglycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 2.2-thousone ethylenebis(3-( 3,5-
tert-phthyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3
-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexaradio-rubis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)
Hydroquine phenyl)propione-;-:],]2.4
-bis-n-octylthio)-6-(4-hydroquino-
3,5-tert-butylanili/)-1,3,5
-trialene, octadecyl-3-(3,5-di-te)
rt-butyl-4-hydroxyphenyl) propionate,! , 3.5-trimethyl-2.4.6-tris(3
, 5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2-thiobis(4-methyl-5-te
rt-butylphenol), 1.3.5-tris(4-
tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, N,N'-hexamethylenebis(3,5
-di-tert-butyl-4-hydroxy-hydrocinnamami →, bis(3,5-di-tert-butyl-4
-ethyl hydroxybenzylphosphonate) carunium,
N, N'-bis(3,r-(3.

5-tert-butyl-4-hydroxyphenyl)
propynyl]hydrazine, 2-(2-hydroquine-3
,5-bis(α,α-dimethylbenzyl)phenyl)-
2H-benzotriazole, 2-(3,5-di-te
rt-7mil-2-hydroxyphenyl)benzotriazole, 2-(3-tert-butyl-5-methyl-
2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2
-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole, stearyl 3-(3,
5-tert-butyl-4-hydroxyphenyl)
Propionate or 2,2-bis(3-(3,5-
Di-tert-butyl-4-hydroxyphenylbropanoyluoquine)methyl)-1,3-propanediolbis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

The amount of the hindered phenol antioxidant used in the present invention is 0.001 to 0.001 to the oxymethylene copolymer.
5% by weight, preferably 0.05-3% by weight. 0.
If it is less than 0.001% by weight, the thermal stability of the resulting composition will be low, and if it is more than 5% by weight, it will precipitate in the form of white powder on the surface of the oxymethylene copolymer, which is not preferable.

Examples of reagents capable of absorbing formaldehyde used in the present invention include amide compounds, urethane compounds, pyridine derivatives, pyrrolidone derivatives, urea derivatives, triazine derivatives, hydrazine derivatives, and amidine compounds. N-dimethylformamide, N
, N-dimethylacetamide, N,N-diphenylformamide, N,N-diphenylacetamide, N,'
Single lactams such as N-diphenylbenzamide, N,N,N,, N-tetramethyladipamide, oxalic acid dianilide, adipic acid dianilide, α-(N-phenyl)acetanilide, nylon 6, nylon If nylon 12 Polyamides derived from polymers or copolymers, dicarboxylic acids such as adipic acid, sebacic acid, decanedicarboxylic acid, dimic acid and diamino acids such as ethylene diamine, tetramethylene diamine, hexamethylene diamine, metaxylylene diamine. Homopolymers or copolymers, polyamide copolymers derived from lactams, dicarboxylic acids and diamines, polyacrylamide, polymethacrylamide, N,N-bis(hydroxymethyl)speramide, poly(γ-methylglucmate) , poly(<r-ethylglutamate), poly(N-vinyllactam), poly(N-vinylpyrrolidone), and other amide compounds; diisocyanates such as toluene diisocyanate and diphenylmethane diisocyanate;
．． Polyurethanes derived from glycols such as 4-butanediol and polymeric glycols such as poly(tetramethylenediamine) glycol, polybutylene adipate, polycaprolactone, melamine, benzoguanamine, acetoguanamine, N-butylmelamine, N-phenylmelamine, N,N-diphenylmelamine, NlNl
N-triphenylmelamine, N-methylolmelamine,
N,N-dimethylolmelamine, N,N,N-)limethylolmelamine, 2,4-diamino-6-benzyloxytriazine, 2,4-diamino-6-butoxytriazine, 2,4-diamino-6- Triazine derivatives such as cyclohexyltriazine, melem, melam, N-phenylurea, N, N-diphenylurea, thiourea, N
- Urea derivatives such as phenylthiourea, N,N-diphenylthiourea, nonamethylene polyurea, phenylhydrazone, diphenylhydrazine, benzaldehyde hydrazone, semicarbazone, 1-methyl-1-phenylhydrazone, thiosemicarbazone, 4-( hydrazone of dialkylamino)benzaldehyde, ■-methyl-1-
Hydrazine derivatives such as phenylhydrazone and thiosemicarbazone, dicyanreamide, guantidine, guanidine, aminoguanidine, guanineacrine, guanochlor, guanoxane, guanosine, amiloride, N-amidino-3-amino-6-chloropyrazinecarboxy Amidine compounds such as amides, poly(2-vinylpyridine), poly(2-methyl-5-vinylpyridine)
, poly(2-ethyl-5-vinylpyridine), 2-vinylpyridine-2-methyl-5-vinylpyridine copolymer, and pyridine derivatives such as 2-vinylpyridine-styrene copolymer.

Among them, dimic acid polyamide, melamine, guanamine, benzoguanamine, N-methylolated melamine, N-
Methylorated benzoguanamine, thermoplastic polyurethane resin, resinamide, guanidine, poly(vinylpyrrolidone), poly(2-vinylpyridine), polyurea, melem, and melam have excellent thermal stability as oxymethylene copolymers containing them. Therefore, it is preferable.

The amount of the agent capable of absorbing formaldehyde added is 0.001 to 5% by weight, preferably 0.05 to 3% by weight, based on the oxymethylene copolymer. O,OO
If it is less than 1% by weight, the resulting composition will have insufficient thermal stability, and if it is more than 5% by weight, it may precipitate on the surface of the composition or cause the composition to be colored, which is not preferable.

In the composition of the present invention, trioxane and a cyclic ether are polymerized using a boron trifluoride catalyst, the polymerization reaction is stopped by adding a hindered amine compound as a catalyst deactivator, and an alkali metal or alkaline earth metal salt,
Manufactured by adding and kneading a hindered phenolic antioxidant and a formaldehyde absorbent. The additives may be sequentially added one by one, or may be added all at once. Moreover, the additive may be added as it is, or may be added as a solution of an organic solvent.

Examples of organic solvents include aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as n-hexane, n-hebutane, and cyclohexane, alcohols such as methanol and ethanol, chloroform, Examples include dichloromethane, 1.2-; halogenated hydrocarbons such as chloroethane, acetone, and ketones such as methyl ethyl ketone.

The composition of the present invention may also include fillers such as calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, mica powder, carbon fiber, glass fiber, ceramic fiber, aramid, etc., to the extent that the effects of the present invention are not impaired. Reinforcing agents such as fibers, coloring agents (pigments, dyes), nucleating agents, plasticizers, mold release agents, flame retardants, antistatic agents, conductive agents, adhesives, lubricants, hydrolysis resistance improvers, adhesion aids, etc. can be optionally included.

The oxymethylene copolymer composition produced according to the present invention has excellent moldability, mechanical properties, melt stability, and heat aging resistance, so it can be used in a wide range of applications such as mechanical parts, automobile parts, and electrical/electronic parts. It can be used in

<Examples> Next, the present invention will be described with reference to Examples and Comparative Examples. In addition,
The surface condition, mechanical properties, relative viscosity pr, thermal decomposition rate K, and polymer melting point (T
m ) and crystallization temperature (TC) were measured as follows.

Surface condition of molded product: Using an injection molding machine with an injection capacity of 5 ounces, the cylinder temperature was 230°C, the mold temperature was 60°C, and the molding cycle was 5.
ASTMI dumbbell test specimens and Izotsu impact test specimens were injection molded using a setting of 0 seconds. The surface condition of the obtained ASTM No. 1 dumbbell test piece was observed with the naked eye.

Mechanical properties: Tensile properties were measured according to the ASTM D-638 method using the ASTMI dumbbell test piece obtained by the above injection molding. In addition, using Izotsu impact test pieces, ASTM D-2
The impact strength was measured according to the 56 method.

Relative viscosity 'Pr: p-chlorophenol containing 2% α-pinene
0.5 Da of polymer was dissolved in QO@/ and measured at a temperature of 60°C.

Thermal decomposition rate Kx: Kx is faithful to the decomposition rate when left at x'C for a certain period of time, and using a thermobalance device, approximately IO'q of sample is heated at xC under an air atmosphere. It was determined by the following formula.

KX=(Wo Wl ) X 100/WO% Here, Wo means the sample weight before heating, and Wl means the sample weight after heating.

The thermal balance device is a DuPont thermal analyzer 109.
0/1091 was used.

Polymer melting point (Tm), crystallization temperature (Tc): Using a differential scanning calorimeter, the temperature was raised at a rate of 10°C/min in a nitrogen atmosphere, and after measuring the polymer melting point (Tm), the lo The temperature was lowered at a rate of 'c/min, and the crystallization temperature (Tc) was measured.

Reference example 1 A 3-liter kneader with two Σ-type stirring blades was heated at 60°C.
3.0# of trioxane, 1.3-dioxolane 112F, and boron trifluoride/diethyl etherate as a catalyst at 200 pp per 2 weights of trioxa.
Add m as a 10% benzene solution and stir at 30 rpm.

The contents solidified within a few minutes and the temperature inside the system rose due to reaction heat and frictional heat, so a cold kite was passed inside the Σ-type stirring blade to cool it down, and the rotation speed was further lowered to 1 Orpm to bring the maximum temperature to 80°C. controlled until now.

Stirring was continued, and the polymer was taken out after 60 minutes.

The obtained polymer was a white powder with F r = 2.37.

This polymer will be referred to as oxymethylene copolymer A.

2 Example 2 In Reference Example 1, instead of 1,3-dioxolane,
The polymer was bulk polymerized in the same manner as in Reference Example 1, except that ethylene oxide 661 was used.

j What is the smoothed polymer? ) It was a white powder with r = 2.40.

This polymer will be referred to as oxymethylene copolymer B.

Examples 1-5. Comparative Examples 1 to 2 To the t-oxymethylene copolymer A obtained in Reference Example 1, various hindered amine compounds represented by the above structural formulas were added in the proportions shown in Table 1 as an approximately 20% benzene solution.
The mixture was kneaded for 15 minutes at 5°C. Then 0.1% by weight of calcium hydroxide and 0.5% by weight of pentaerythrityl-
Tetrakis(3-(3,5-di-tert-butyl-4)
-Hydroxyphenyl]propionate] (Ciba-
'Irganox' 1010 (manufactured by Geigy) was added, and the temperature was raised to 210°C for 10 minutes, and then heated at the same temperature for 20 minutes.
Kneaded for a minute. Further, 0.1% by weight of dicyandiamide was added and kneaded at 210°C for 10 minutes.

For comparison, compositions were prepared using triphenylphosphine in place of the hindered amine compound.

Table 1 shows the results of measuring each physical property of the obtained composition. Table 1
It is clear from the above that the composition according to the present invention has excellent physical properties regardless of the type of hindered amine compound.

Example 6 To the oxymethylene copolymer A obtained in Reference Example 1, a hindered amine compound, calcium hydroxide, Irganox"l 010, and dianediamide were added all at once in the same proportions as in Example 2, and the mixture was heated at 35°C. The mixture was kneaded for 15 minutes.Then, the temperature was raised to 210°C over 10 minutes, and the mixture was kneaded for 30 minutes at the same temperature.The results of various physical property measurements of the resulting composition are shown in Table 1.
Shown below.

Example 7 A hindered amino compound, calcium hydroxide, and "Irganox"l 010 were simultaneously added to the oxymethylene copolymer A obtained in Reference Example 1 in the same proportions as in Example 2, and the mixture was heated at 35°C for 15 minutes. Kneaded for a minute.

Thereafter, the temperature was raised to 210° C. over 10 minutes, and the mixture was kneaded at the same temperature for 20 minutes. Thereafter, 0.1% by weight of ginandiamide was added, and the mixture was kneaded at the same temperature for 10 minutes.

Table 1 shows the results of various physical property measurements of the obtained composition.

Example 2 (@ next addition method), Example 6 (batch addition method),
It is clear from Example 7 (all ingredients other than the formaldehyde absorbent were added at once) that the composition of the present invention has excellent physical properties regardless of the kneading method.

Examples 8 to 13 Compositions were produced in the same manner as in Examples 2.6.7, except that magnesium hydroxide and potassium carbonate were used instead of calcium hydroxide.

Table 2 shows the results of various physical property measurements of the obtained composition. Table 2
More clearly, it can be seen that the composition of the present invention has excellent physical properties regardless of the type of alkali or alkaline earth metal salt and the kneading method.

Examples 14 to 19 Triethylene glycol-bis(
3-(3-tert-butyl-5-methyl-4-hydroxyphenylpropione-1-) (C1ba -G
“Irganox” 245) manufactured by Eigy, N,
N'-hexamethylene bis(3,5-tert
-butyl-4-hydroquine-hydrocin t')
('Irganox' manufactured by Ciba-Geigy)
A composition was prepared in the same manner as in Example 2.6.7 except that 1 O98) was used.

Table 3 shows the results of various physical property measurements of the obtained composition. Table 3
More clearly, it can be seen that the composition of the present invention has excellent physical properties regardless of the type of antioxidant and the cross-fertilization method.

Examples 20 to 25 Compositions were produced using the same tJ as in Examples 2.6.7, except that melamine and dimic acid polyamide were used instead of dicyandiamide.

Table 4 shows the results of various physical property measurements of the obtained composition. Table 4
More clearly, it can be seen that the composition of the present study has excellent physical properties regardless of the formaldehyde absorbent and the kneading method.

Examples 26-37 Examples 2.6-10.14-16.20-2 except for using oxymethylene copolymer B obtained in Reference Example 2
A composition was produced in the same manner as in Example 2.

1 Table 5 shows the results of various physical property measurements of the obtained composition. Table 5 clearly shows that even if the copolymerization components are changed, exactly the same compositions can be obtained.

<Effects of the Invention> The oxymethylene copolymer composition produced according to the present invention has excellent not only melt stability but also mechanical properties, so it is widely used in mechanical parts, automobile parts, electric/electronic parts, etc. It can be used for various purposes.

Claims (1)

[Claims] Polymerization of a mixture of trioxane and a cyclic ether with at least one member selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. A type selected from alkali metal, alkaline earth metal hydroxides, inorganic acid salts, organic acid salts, and alkoxides for polymers that are subjected to bulk polymerization in the presence of a catalyst and then deactivated by adding a hindered amine. The above-mentioned oxymethylene copolymer composition is prepared by adding and mixing a hindered phenol antioxidant and an agent capable of reacting with formaldehyde and absorbing formaldehyde.