JPH055017A - Polyoxymethylene copolymer and its production - Google Patents

Abstract

PURPOSE:To obtain a polyoxymethylene copolymer excellent in stability and mechanical properties. CONSTITUTION:A polyoxymethylene copolymer, composed of oxymethylene units and oxyalkylene units and having 10000-200000 molecular weight and 0.07-0.5mol% oxyalkylene units based on the oxymethylene units at <=0.025 ratio of absorbance of terminal formates to that of methylene groups measured by infrared ray spectrophotometry.

Description

Detailed Description of the Invention

[0001]

This invention relates to polyoxymethylene copolymers. More specifically, the present invention relates to a polyoxymethylene copolymer having a limited terminal group composition and excellent stability and mechanical properties.

[0002]

2. Description of the Related Art Polyoxymethylene synthesized by a conventional technique is roughly classified into a homopolymer and a copolymer. The polyoxymethylene homopolymer and the polyoxymethylene copolymer each had only either excellent mechanical properties or excellent stability. That is, the polyoxymethylene homopolymer obtained by homopolymerizing formaldehyde or trioxane has excellent mechanical properties, but its stability cannot be said to be sufficient. On the other hand, a polyoxymethylene copolymer obtained by copolymerizing formaldehyde or trioxane with a cyclic ether or cyclic formal is excellent in stability but inferior in mechanical properties. Moreover, polyoxymethylene copolymers are not sufficient in terms of long-term heat resistance or hot water resistance.

Polyoxymethylene copolymers are usually obtained by copolymerizing formaldehyde or trioxane with cyclic ethers. US Patent No. 3,02
No. 7,352 describes a copolymer obtained by cationically copolymerizing trioxane with ethylene oxide and 1,3-dioxolane.

Also, US Pat. No. 3,337,503 discloses the use of methylal as a molecular weight regulator during the polymerization of trioxane. When methylal is used as a molecular weight regulator, the terminal group of the polymer obtained becomes a methoxy group.

When polymerizing formaldehyde or trioxane using a cation catalyst or copolymerizing with a comonomer, a hydride shift (hydrogen abstraction reaction) occurs, the main chain of the polymer is cleaved, and a high molecular weight polymer can be obtained. Can not. Moreover, it is known that the cleaved ends become a methoxy group and a formate group.

Further, at the time of copolymerization, when a compound having a hydroxyl group such as water, methanol and formic acid is present, they function as a chain transfer agent and form an unstable terminal structure.
Usually, post-treatment after polymerization decomposes these unstable terminal structures and stabilizes the terminal groups as hydroxyethoxy groups, but in the case of formic acid,
Furthermore, terminal formate groups are simultaneously formed.

[0007]

As described above, in the conventional polyoxymethylene copolymer, the terminal formate group is changed by chain transfer reaction by formic acid which is an impurity in trioxane at the time of polymerization and hydride shift reaction which is a side reaction by a cation catalyst. Formed and therefore it was difficult to reduce the terminal formate groups.

The present invention relates to a polyoxymethylene copolymer having both excellent stability and excellent mechanical properties. More specifically, it relates to a polyoxymethylene copolymer excellent in stability and mechanical properties, long-term heat resistance and hot water resistance, and a method for producing the same.

[0009]

Means and Actions for Solving the Problems The present inventors have
As a result of earnest research on the stability of polyoxymethylene,
By limiting the amount of oxyalkylene units inserted in the polyoxymethylene copolymer and the amount of formate groups at the ends of the copolymer to a certain range, extremely excellent stability and mechanical properties, and excellent long-term heat resistance and It was found that a polyoxymethylene copolymer having hot water resistance was obtained, and the present invention was completed.

That is, the present invention relates to an oxymethylene unit (--CH ₂ O--) and an oxyalkylene unit.

[0011]

[Chemical 2] (R, R ₀ : selected from hydrogen, an alkyl group and an aryl group, and may be the same or different, n = 1 to 5,
a polyoxymethylene copolymer having a molecular weight of 10,000 to 200,000, characterized by satisfying the following conditions (a) and (b): ) Oxyalkylene units are 0.07 to 0.5 mol% per oxymethylene unit. (B) In the infrared spectroscopic measurement of the polymer, the absorbance of the terminal formate group is 0.025 with respect to the absorbance of the methylene group.
It is below. It is about.

Next, the present invention will be specifically described.

The polyoxymethylene copolymer of the present invention is
Formaldehyde or trioxane with general formula

[0014]

[Chemical 3] (R and R _{0 are the} same or different and are selected from hydrogen, an alkyl group and an aryl group, and R bonded to different carbon atoms and R ₀ bonded to different carbon atoms are the same or different and are hydrogen and alkyl groups. , An aryl group, a cyclic ether represented by m = 2 to 6), or a general formula

[0015]

[Chemical 4] (R and R _{0 are the} same or different and are selected from hydrogen, an alkyl group and an aryl group, and R bonded to different carbon atoms and R ₀ bonded to different carbon atoms are the same or different and are hydrogen and alkyl groups. , An aryl group, and a cyclic formal represented by m = 2 to 6) can be obtained by copolymerizing with a cationic catalyst.

Examples of the cyclic ether used to obtain the polymer of the present invention include ethylene oxide, propylene oxide, butylene oxide, styrene oxide and the like.

Examples of the cyclic formal include ethylene glycol formal (1,3-dioxolane), diethylene glycol formal, 1,3-propanediol formal, 1,4-butanediol formal,
Examples include 1,5-pentanediol formal and 1,6-hexanediol formal. A particularly preferred comonomer is ethylene glycol formal (1,3-
And cyclic formal such as 1,4-butanediol formal.

The polymer of the present invention can also be obtained by reacting a polyacetal homopolymer with the above cyclic ether or cyclic formal in the presence of a cation catalyst.

In the present invention, one of the important points is the insertion amount of the polyalkylene unit in the polymer.

That is, the insertion ratio of oxyalkylene units in the polymer is 100 mol of oxymethylene units,
0.07 to 0.5 mol, more preferably 0.1 to 0.3
Only in the range of mol, a polyoxymethylene copolymer having excellent mechanical properties and stability, long-term heat resistance, and hot water resistance can be obtained. If the insertion rate of oxyalkylene units is less than 0.07 mol, stability, long-term heat resistance, and hot water resistance deteriorate. On the other hand, when the insertion rate of oxyalkylene units exceeds 0.5 mol, the mechanical properties are significantly deteriorated.

The sequence of the oxyalkylene units is also an important point, and the oxyalkylene units should be dispersed alone in the polymer as long as they can be formed without forming a block, stability, mechanical properties, heat resistance, and hot water resistance. From the viewpoint of improving

As for n representing a sequence of oxyalkylene units, a ratio of n = 1 is 95 in the whole oxyalkylene unit.
The proportion of mol% or more and n ≧ 2 is preferably 5 mol% or less of the entire oxyalkylene unit.

The insertion amount and sequence of these oxyalkylene units can be determined by thermally decomposing the polymer in a 3N HCl aqueous solution and analyzing the alkylene glycol, dialkylene glycol, and trialkylene glycol in the decomposing solution. it can.

Next, one of the other important points is the amount of terminal formate of the copolymer.

In the present invention, the terminal group of the polymer is an alkoxy group such as methoxy group (--OCH ₃ ) or a hydroxyalkoxy group.

[0026]

[Chemical 5] (R and R _{0 are the} same or different and are selected from hydrogen, an alkyl group and an aryl group, and R bonded to different carbon atoms and R ₀ bonded to different carbon atoms are the same or different and are hydrogen and alkyl groups. , An aryl group, m = 2 to 6), a formate group and the like. A terminal group other than these, for example, a hydroxyl group added to an oxymethylene unit is extremely unstable, and must be decomposed and removed by a post-treatment after polymerization, for example, thermal decomposition in the presence of an alkaline substance to form a hydroxyalkoxy group. I have to.

The amount of formate end groups of the copolymer can be measured by infrared spectroscopy of a film obtained by hot pressing the polymer. The absorption wave number (ν) due to the terminal formate was 1710 cm ⁻¹ , and the absorption wave number (ν) due to the methylene group of the polyoxymethylene main chain was 1470 c
m ^-1 . The amount of terminal formate groups in the copolymer can be expressed by the ratio of these absorbances D ₁₇₁₀ / D ₁₄₇₀ .

The amount of formate groups in the copolymer of the present invention should be 0.025 or less, preferably 0.020 or less as D ₁₇₁₀ / D ₁₄₇₀ . When D ₁₇₁₀ / D ₁₄₇₀ exceeds this range, the stability, heat resistance and hot water resistance of the copolymer deteriorate.

As described above, the stability, mechanical properties, long-term heat resistance and hot water resistance of the polyoxymethylene copolymer are improved only when the limited insertion amount of oxyalkylene units and the amount of terminal formate groups are satisfied. Excel.

In order to obtain the polymer of the present invention, that is, a polyoxymethylene copolymer having a limited amount of terminal formate groups and excellent in stability, mechanical properties, long-term heat resistance and hot water resistance. As the cationic polymerization catalyst used,
Perfluoroalkyl sulfonic acids or their derivatives are suitable. Specifically, for example, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, undecafluoropentanesulfonic acid, perfluoroheptanesulfonic acid, and the like, and as a derivative, trifluoromethane Super strong acid anhydride such as sulfonic acid anhydride, pentafluoroethanesulfonic acid anhydride, heptafluoropropanesulfonic acid anhydride, nonafluorobutanesulfonic acid anhydride, undecafluoropentanesulfonic acid anhydride, perfluoroheptanesulfonic acid anhydride Or methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, ethyl pentafluoroethanesulfonate, methyl pentafluoroethanesulfonate, heptafluoropropanesulfone Superacid alkyl esters such as methyl or trimethylsilyl trifluoromethanesulfonate, etc. superacid alkylsilyl esters such as trifluoromethanesulfonic acid triethylsilyl and the like.

Usually, Lewis acids such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, phosphorus pentachloride and compounds or salts thereof are used as catalysts for the polymerization or copolymerization of trioxane. There is. However, when these catalysts are used, the hydride shift, which is a side reaction at the time of polymerization, is large, and the amount of terminal formate group of the obtained copolymer satisfies D ₁₇₁₀ / D ₁₄₇₀ of 0.025 or less. It is very difficult to do. Further, these catalysts do not always have sufficient polymerization activity, and satisfactory polymerization cannot be achieved unless the catalyst concentration is increased. Therefore, the residual catalyst concentration of the polymer after polymerization becomes high, and the thermal stability is lowered. Therefore, a complicated process such as washing and removing the catalyst after polymerization is required.

The catalyst concentration of the present invention is based on the main monomer.
It should be in the range of 1 × 10 ^{−6 to} 2 × 10 ⁻⁵ mol%. At concentrations below this, polymerization does not occur. On the other hand, if the concentration is higher than this, the catalyst remaining in the polymer causes depolymerization, which lowers the thermal stability of the polymer.

As described above, when the present inventors used perfluoroalkylsulfonic acid or its derivative as a catalyst, the hydride shift, which is a side reaction during the polymerization, can be suppressed, and D ₁₇₁₀ / D ₁₄₇₀ is 0. It has been found that a polyoxymethylene copolymer satisfying 0.025 or less can be obtained.

Further, when the present inventors use perfluoroalkyl sulfonic acid or its derivative as a catalyst,
It was found that the amount of water and formic acid contained in the monomer has a great influence on its polymerization activity. That is, in the present invention, the concentrations of water and formic acid in the monomer must be 40 ppm or less. When it exceeds 40 ppm, the polymerization activity is extremely lowered, and in the catalyst concentration range of 1 × 10 ⁻⁶ to 2 × 10 ⁻⁵ mol% with respect to the main monomer, the polymerization does not start at all, or Polymerization yield is extremely low and not practical.

Alcohols and ethers are preferred as the molecular weight regulator during polymerization, and alkyl ethers such as methylal are most preferred. In addition, water, formic acid, methyl formate, etc. also act as a molecular weight regulator, but in the present invention,
In particular, water and formic acid have effects on the above catalytic activity,
It cannot be used. Methyl formate is also not preferred because it forms a terminal formate group. Therefore, when water, formic acid, or methyl formate is contained as an impurity in the monomer, it is necessary to purify it before the polymerization to reduce these impurities as much as possible.

The molecular weight of the polymer of the present invention is 10,000.
Should be in the range of up to 200,000. Molecular weight is 1
When it is less than 10,000, sufficient mechanical properties cannot be obtained, and when it has a molecular weight of more than 200,000, the workability such as molding and extrusion is remarkably reduced, which is not practical.

The polymerization apparatus used in the present invention may be either a batch type or a continuous type and is not particularly limited. Generally, a reaction tank with a stirrer can be used as a batch type polymerization device, and a continuous device is a self-cleaning device such as a co-kneader, a twin-screw type continuous extrusion kneader, and a two-axis paddle type continuous mixer A mold mixer can be used. The polymerization temperature is 60 to 200 ° C., preferably 60 to 200 ° C.
It can be performed at 140 ° C. The polymerization time is not particularly limited, but generally 10 seconds or more and 100 minutes or less is selected.

After the polymerization, the catalyst contained in the polymerized polymer undergoes depolymerization, so that the catalyst is usually deactivated. Generally, a method of neutralizing and inactivating by contacting with an aqueous solution containing a basic substance such as triethylamine or an organic solvent, or by adding and mixing the basic substance to melt is carried out. As a result of earnest research on the deactivation method of the polymerization catalyst, the present inventors have found that at least 2
We have found a very effective method of deactivating by adding and mixing a crystalline acid adsorbent composed of more than one kind of metal oxide or metal hydroxide. More specifically, for the polyoxymethylene copolymer, a. An ion adsorbent containing, as a main component, at least two oxides of at least one selected from oxides of alkali metals and alkaline earth metals and at least one selected from oxides of trivalent and tetravalent elements. Or b. General formula M1 _1-x M2 _x (OH) _{2 An} ^- _{x / n} · mH ₂ O (wherein M1 represents at least one divalent metal selected from alkaline earth metals, and M2 is trivalent) Showing metal,
A ^n- represents an n-valent anion. Also, x is 0 <x ≦ 0.5.
And m is a positive number. ) Ion adsorbent represented by. At least one selected from 0.001 to 0.5
wt% More preferably 0.005 to 0.1 wt% is added and melt mixed. Here, examples of the alkali metal oxide include Na ₂ O and K ₂ O, examples of the alkaline earth metal oxide include MgO and CaO,
Further, as oxides of trivalent and tetravalent elements, Al ₂ O ₃ ,
Examples thereof include SiO ₂ and TiO ₂ . As the ion adsorbent containing at least two kinds of oxides selected from these oxides as main components, specifically, 2.5MgO.Al ₂ O ₃
nH ₂ O, 2MgO · 6SiO ₂ · nH ₂ O, Al ₂ O
_{3 · 9SiO 2 · nH 2 O} , Al 2 O 3 · Na 2 O · 2
CO ₃ .nH ₂ O, Mg _0.7 Al _0.3 O _{1.15 and the} like can be mentioned. In addition, the general formula M1 _1-x M2 _x (OH) ₂ A ^n- _{x / n} · m
In H ₂ O, examples of M1 include Mg, Ca, and M
Examples of 2 are B, Al, Ga, In, Ti, Tl.
Etc., CO ₃ ^2-Examples of _{^{A n-, OH -, HCO 3}} -, H
₂ PO ₄ ⁻ , NO ₃ ⁻ , I ⁻ , salicylate ion ⁻ , citrate ion ⁻ , tartrate ion ^{− and the} like. Particularly preferable examples include CO ₃ ²⁻ and OH ⁻ . As a specific example of this kind of ion adsorbent, Mg _0.75 Al
_0.25 (OH) ₂ CO _{3 0.125} · Natural hydrotalcite represented by 0.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ C
There is a synthetic hydrotalcite represented by O ₃ .3.5H ₂ O and the like.

The amount of these deactivators added is based on the polymer.
0.001 to 0.5 wt% is preferable, and 0.005 to 0.1 wt% is more preferable. Addition amount is 0.001
If it is less than wt%, the deactivation of the polymerization catalyst is insufficient, and
When the addition amount is 0.5 wt% or more, the coloring occurs at the time of molding and the color tone of the molded product is deteriorated. The particle size of the quenching agent is not particularly limited, but is preferably 100 μm or less in order to improve dispersibility. Further, the deactivator may be surface-treated in order to improve dispersibility with the polymer.

The deactivator may be added to the polymerization machine after completion of the polymerization, or in a continuous polymerization machine, to the latter stage of the polymerization machine, or by adding and mixing to the polymer discharged from the polymerization machine. I can. The polymer added with the deactivator,
Further, by melt-mixing, the polymerization catalyst can be deactivated more completely. Melt mixing is from the melting point of the polymer to 2
It is carried out in the temperature range of 70 ° C. As a melt mixing device, a single screw type continuous extruder, a co-kneader, a 2
Axial screw type continuous extruder and the like can be mentioned.

When the obtained copolymer has an unstable terminal hydroxyl group, the unstable portion is decomposed and removed by heat treatment with a basic substance such as an aqueous solution of triethylamine by a conventionally known method. To do. Further, this operation can be carried out simultaneously with the operation of adding and mixing the catalyst deactivator, or by the same melt mixer.

[0042]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples.

The measurement items in the examples are as follows.

1. Terminal formate: 200 ° C of copolymer
Hot press to form a 15μ film. Taking the infrared absorption spectrum of the obtained film, ν = 1710c
Ratio D of the absorbance at m ^-1 to the absorbance at ν = 1470 cm ^-1
Calculate ₁₇₁₀ / D ₁₄₇₀ .

2. Insertion amount and sequence of oxyalkylene unit: 10 g of copolymer to 100 ml of 3N HCl
Put in an aqueous solution and heat in a sealed container at 120 ° C. for 2 hours to decompose. After cooling, the amounts of alkylene glycol, dialkylene glycol and trialkylene glycol in the aqueous solution are measured by gas chromatography (FID), and the amount of oxyalkylene units is expressed by mol% based on the oxymethylene units of the copolymer. The sequence of oxyalkylene units corresponds to an amount of monoalkylene glycol of n = 1, an amount of dialkylene glycol of n = 2 and an amount of trialkylene glycol of n = 3.

3. MI: ASTM D-1238-86
based on.

4. Thermal stability: Resin is retained in an injection molding machine (Arburg All Rounder 100, manufactured by Western Trading Co., Ltd.) with a cylinder temperature of 230 ° C. to mold a 12 × 120 × 3 mm molded piece, and a silver streak is formed on the surface of the molded piece. Then, the time (min) at which is generated is obtained. The higher the value, the better the thermal stability of the polymer.

5. Heat-resistant aging: ASTM D-63
The tensile test piece based on No. 8 was held in a 140 ° C. gear oven (manufactured by Tabai Seisakusho, GPS-222 type) and evaluated. The measurement item is the tensile strength retention rate.

6. Hot water resistance: A tensile test piece based on ASTM D-638 was evaluated by immersing it in hot water (running water type) adjusted to 120 ° C. The measurement item is the tensile strength retention rate.

Note) Explanation of abbreviations in the table A-1: trifluoromethanesulfonic acid A-2: trifluoromethanesulfonic anhydride A-3: trifluoromethanesulfonic acid methyl ester A-4: trifluoromethanesulfonic acid trimethylsilyl ester A -5: Boron trifluoride dibutyl etherate B-1: Mg _0.75 Al _0.25 O _1.125 B-2: Al ₂ O ₃ .Na ₂ O.2CO ₃ .H ₂ O B-3: Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3H ₂ O B-4: Al ₂ O ₃ .9SiO ₂ .H ₂ O B-5: triethylamine C-1: 1,3-dioxolane C-2: 1,3-propanediol formal C-3 : 1,4-Butanediol formal C-4: 1,6-hexanediol formal C-5: ethylene oxide Example-1 Highly purified trioxa (Water in the trioxane 2p
pm, formic acid 3 ppm) 2000 g, 1,3-dioxolane (0.8 mol% with respect to trioxane), and methylal (0.2 mol% with respect to trioxane) were put in a kneader equipped with a jacket having two Σ blades.
The temperature was raised to 0 ° C. Then, a solution of trifluoromethanesulfonic acid in dioxane (0.002 mol / l) was added to trioxane in an amount of 5 × 10 ^{−6 with} respect to trioxane.
Polymerization was carried out by adding so that the amount became mol%. After starting the reaction,
After 15 minutes, cold water was put into the jacket and cooled in a nitrogen atmosphere. One hour later, the content of the kneader was taken out, and Mg _0.75 Al _0.25 O _1.125 (Kyoward KW2300 Kyowa Kagaku Co., Ltd.) was added as a deactivator in an amount of 0.01 wt% to the obtained polymer, and a biaxial extruder with a vent was used. Extruded at 200 ° C. Furthermore, 1 part by weight of triethylamine, 5 parts by weight of water, and 2,2-methylenebis- (4-methyl-6-) were added to 100 parts by weight of the obtained polymer.
0.2 parts by weight of t-butylphenol) was added and extruded by a vented single-screw extruder (extrusion temperature: 200).
C., vent pressure 200 torr). The terminal formate, the amount of oxyalkylene units inserted, the sequence of oxyalkylene units, MI, thermal stability, heat aging, and hot water resistance of the obtained copolymer were evaluated. The results are shown in Table 1.
~ Shown in Table 4.

The polymerization yield was as high as 89%, and D ₁₇₁₀ / D _1470, which represents the amount of terminal formate groups, was as small as 0.01. Regarding the oxyalkylene unit, the amount of diethylene glycol was 0.
It was a very small amount of 3 mol%.

Regarding the physical properties of the polymer, the thermal stability was good and the tensile strength was also excellent. Furthermore, both the heat-resistant aging and the hot water resistance were good at a tensile strength retention of 80% or more after 2000 hours.

Examples-2 to 18 In the same manner as in Example-1, the catalyst amount, the water content in the monomer, the formic acid in the monomer, the amount of 1,3-dioxolane, the amount of methylal, the kind of the comonomer and the like were determined. Instead, various polyoxymethylene copolymers were synthesized under the conditions shown in Table 1. The obtained polymer was treated in the same manner as in Example-1 and evaluated in the same manner. The results are shown in Tables 1 to 4. Similar to Example-1, all had a high polymerization yield and a small amount of terminal formate. Also, the thermal stability was good, and the tensile strength was also excellent. Furthermore, heat-resistant aging,
The hot water resistance was excellent, and the tensile strength retention rate after 2,000 hours was 80% or more.

Examples-19 to 23 Polyoxymethylene copolymers were synthesized in the same manner as in Example-1, except that the type of catalyst and the amount of catalyst were changed under the conditions shown in Table 1. The obtained polymer was treated in the same manner as in Example-1 and evaluated in the same manner. The results are shown in Tables 1 to 4. Similar to Example-1, all had a high polymerization yield and a small amount of terminal formate. Also, the thermal stability was good, and the tensile strength was also excellent. Furthermore, heat-resistant aging,
The hot water resistance was excellent, and the tensile strength retention rate after 2,000 hours was 80% or more.

Comparative Example-1 Using the apparatus of Example-1, boron trifluoride dibutyl etherate (0.02 mol / L benzene solution) was used as a polymerization catalyst, and the catalyst concentration was 5 × with respect to trioxane.
A polyoxymethylene copolymer was synthesized by the same method as in Example 1 except that the concentration was 10 ⁻³ mol%, and the polymer taken out was melt-mixed with the quenching agent in the same manner as in Example 1. The obtained polymer was treated in the same manner as in Example-1 and evaluated. The results are shown in Tables 5-8. The amount of terminal formate of the polymer showed a high value of 0.045 in D ₁₇₁₀ / D ₁₄₇₀ . The thermal stability was 48 min, which was significantly lower than that of the example. In addition, both heat aging and hot water resistance were inferior to those of the examples, and the tensile strength retention rate after 2000 hours was 60% or less.

Comparative Examples-2 to 8 Polyoxymethylene copolymers were synthesized using the apparatus of Example-1 under the conditions shown in Table 1 in the same manner as in Comparative Example-1. Under the conditions of Comparative Examples 3 and 4, the polymerization activity was insufficient and a polymer could not be obtained. Under other conditions, a polymer having a lower polymerization yield than that of the example could be obtained. The obtained polymer was treated and evaluated in the same manner as in Comparative Example-1. The results are shown in Tables 5-8. In both cases, the amount of terminal formate of the polymer is 0.017 in D ₁₇₁₀ / D ₁₄₇₀ .
The value was as high as 40 or more. The thermal stability was 50 min or less, which was significantly lower than that of the examples. Further, both heat aging and hot water resistance were inferior, and the tensile strength retention rate after 2000 hours was 50% or less.

Comparative Examples-9 and 10 In the same manner as in Comparative Example-1, a polyoxymethylene copolymer was synthesized using the apparatus of Example-1 under the conditions shown in Table 1. When 30 minutes passed after the initiation of the polymerization, 1 liter of a 5 wt% triethylamine aqueous solution was supplied to deactivate the polymerization catalyst and terminate the polymerization. The obtained polymer was filtered and heated (135 ° C.) and dried under a nitrogen stream. Then, 1 part by weight of triethylamine, 5 parts by weight of water, and 0.2 parts by weight of 2,2-methylenebis- (4-methyl-6-t-butylphenol) were added to 100 parts by weight of the obtained polymer.
It was extruded with a single-screw extruder equipped with a vent (extrusion temperature 200 ° C., vent pressure 200 torr).

The obtained polymer was evaluated in the same manner as in Example-1. The results are shown in Tables 5-8. The amount of terminal formate of the polymer was as high as 0.040 or 0.044 in D ₁₇₁₀ / D ₁₄₇₀ . Thermal stability is also 35 min
Alternatively, it was 40 minutes, which was significantly lower than that of the example. Further, both the heat aging and the hot water resistance were severely deteriorated, and the tensile strength after 2000 hours could not be measured.

Comparative Examples-11 to 16 Using the apparatus of Example-1, under the conditions of Example-1, the amount of trifluoromethanesulfonic acid as the polymerization catalyst, the water content in the monomer, and the concentration of formic acid were changed to obtain polyoxyethylene. A methylene copolymer was synthesized. The results are shown in Tables 5-8. When the catalyst concentration was 1 × 10 ⁻⁶ mol% with respect to trioxane, a polymer could not be obtained. Further, even when the catalyst concentration is 2 × 10 ^{−5 to} 5 × 10 ⁻⁵ mol% with respect to trioxane, a polymer cannot be obtained under the condition that water or formic acid in the monomer is as high as 50 ppm or more, or The polymerization yield was significantly reduced. Further, when the catalyst concentration was 5 × 10 ⁻⁵ mol% with respect to trioxane, the thermal stability, heat aging and hot water resistance of the obtained polymer were significantly reduced.

Comparative Examples-17 to 20 Polyoxymethylene copolymers were synthesized by using the apparatus of Example-1 and changing the amount of comonomer under the conditions of Example-1. The obtained polymer was treated in the same manner as in Example-1 and evaluated. The results are shown in Tables 5-8. The insertion amount of oxyalkylene unit in the polymer is 0.05mo
When it is 1% or less, the thermal stability, heat aging and hot water resistance of the obtained polymer are significantly lowered. In addition, the insertion amount of oxyalkylene units in the polymer is 0.6 mo.
If it is 1% or more, the tensile strength is significantly reduced.

Examples 24 to 26: A barrel having a jacket having an inner diameter of 50 mm, which partially overlaps with each other, having a jacket through which a heat medium can pass, and a large number of intermeshing paddles inside the barrel. Using a continuous mixing reactor (KRC-kneader Kurimoto Steel Co., Ltd.) consisting of two rotating shafts, with a jacket temperature of 80 ° C.
Trioxane (2 kg / h), 1,3-dioxolane (0.3, 0.8 and 1.4 mol based on trioxane)
%, 3 levels, methylal (0.3 relative to trioxane)
mol%), and trifluoromethanesulfonic acid in dioxane solution (0.002 mol / l) was added to trioxane in an amount of 1 × 10 ⁻⁵ mol based on trioxane.
Polymerization was carried out by continuously supplying it so that the amount became%. The polymer discharged from the polymerizer was taken out under a nitrogen atmosphere, and then Mg _0.75 Al _0.25 O _1.125 (Kyoward KW2300 Kyowa Chemical Co., Ltd.) was added to the polymer as a deactivator to 0.01
wt% added, using a biaxial extruder with a vent,
Extruded at 200 ° C. Furthermore, the polymer 100 obtained
1 part by weight of triethylamine, 5 parts by weight of water,
0.2 parts by weight of 2,2-methylenebis- (4-methyl-6-t-butylphenol) was added, and the mixture was extruded with a vented single-screw extruder (extrusion temperature 200 ° C, vent pressure 200 torr). The obtained copolymer was used in Example-1.
It evaluated similarly to. The results are shown in Tables 1 to 4. In each case, the polymerization yield was high and the amount of terminal formate was small. Also, the thermal stability was good, and the tensile strength was also excellent. Furthermore, both heat aging and hot water resistance are excellent,
The tensile strength retention rate after 2000 hours was 80% or more.

Examples-27 to 31 A polyoxymethylene copolymer was synthesized under the conditions of Example-25, and the deactivating agent shown in Table 1 was used as the deactivating agent after polymerization, and the addition amount was changed to Example- Melt mixing was performed in the same manner as in No. 25. The obtained polymer was treated in the same manner as in Example-25 and evaluated in the same manner. The results are shown in Tables 1 to 8.
All of them had good thermal stability and tensile strength as in Example-1. Furthermore, both heat aging and hot water resistance are excellent, and the tensile strength retention rate after 2000 hours is 80%.
That was all.

Comparative Examples-21 to 25 Polyoxymethylene copolymers were synthesized under the conditions shown in Table 1 in the same manner as in Example-25.

Removal of the polymer from the polymerizer
Example-except that the test was carried out under a nitrogen atmosphere containing 1 vol%.
The same treatment as in Example 25 was conducted to obtain a polyoxymethylene copolymer. The obtained polymer was evaluated in the same manner as in Example-25. The results are shown in Tables 5-8. The terminal formate of the obtained polymer was 0.0 in D ₁₇₁₀ / D ₁₄₇₀ .
It was 3 or more. Each of the obtained polymers was inferior in both heat aging and hot water resistance as compared with the examples.
The tensile strength retention after 000 hours was 60% or less.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

[Table 5]

[0070]

[Table 6]

[0071]

[Table 7]

[0072]

[Table 8]

[0073]

The copolymer of the present invention is excellent in strength, rigidity, fatigue characteristics, friction and wear characteristics, thermal stability, etc., and conventional polyoxymethylene homopolymers and copolymers have been used. Applications such as cams, gears, switches, handles,
It can be used for various mechanical parts such as levers, reels, hubs, bearings, various miscellaneous parts such as fasteners, buttons, clips, and many other automobiles, electric and electronic parts. Further, by utilizing the excellent characteristics of the present copolymer, it can be used for parts around water such as a pump impeller, a pump casing, a shower nozzle, and a faucet. In addition, it is also possible to perform processing such as forming into an extruded rod or sheet and blow molding. In addition, conventionally known additives, for example, various antioxidants, heat stabilizers, pigments, nucleating agents, antistatic agents, various reinforcing materials, such as carbon fiber, glass fiber, glass beads, talc, mica. Etc. can be added and blended. In addition, polyurethane,
Polymer blends with PMMA, PE, etc., and polymer alloys are possible.

Claims (1)

Claims: 1. A oxymethylene units (-CH ₂ O-) and oxyalkylene units ## STR1 ## (R, R ₀ : selected from hydrogen, an alkyl group and an aryl group, and may be the same or different, n = 1 to 5,
m = 2-6), wherein the polyoxymethylene copolymer having a molecular weight of 10,000-200,000 is characterized by satisfying the following conditions (a) and (b): (A) The oxyalkylene unit is 0.07 to 0.5 mol% per oxymethylene unit. (B) In the infrared spectroscopic measurement of the polymer, the absorbance of the terminal formate group is 0.025 with respect to the absorbance of the methylene group.
It is below. 2. In the oxyalkylene unit, n = 1
The polyoxymethylene copolymer according to claim 1, wherein the proportion of the oxyalkylene units is 5 mol% or more of the whole oxyalkylene units. 3. The polyoxymethylene copolymer according to claim 1, wherein the absorbance of the terminal formate group is 0.020 or less with respect to the absorbance of the methylene group in the infrared spectroscopic measurement of the polymer. .. 4. The polyoxymethylene copolymer according to claim 1, wherein the terminal group of the polymer is mainly composed of an alkoxy group, a hydroalkoxy group and a formate group. 5. A polyoxymethylene copolymer comprising: a. An ion adsorbent containing, as a main component, at least two oxides of at least one selected from oxides of alkali metals and alkaline earth metals and at least one selected from oxides of trivalent and tetravalent elements. Or b. General formula M1 _1-x M2 _x (OH) _{2 An} ^- _{x / n} · mH ₂ O (wherein M1 represents at least one divalent metal selected from alkaline earth metals, and M2 is trivalent) Showing metal,
A ^n- represents an n-valent anion. Also, x is 0 <x ≦ 0.5.
And m is a positive number. ) Ion adsorbent represented by. At least one selected from 0.001 to 0.5
The polyoxymethylene copolymer composition according to claim 1 or 2, which comprises wt%. 6. When copolymerizing formaldehyde cyclic oligomer or cyclic acetal as a main monomer in the presence of a comonomer copolymerizable with the main monomer,
Perfluoroalkylsulfonic acid or a perfluoroalkylsulfonic acid derivative is used as a polymerization catalyst in the range of 1 × 10 ⁻⁶ to 2 × 10 ⁻⁵ mol% with respect to the main monomer, and the water content and formic acid in all the monomers are used. 40p each
A method for producing a polyoxymethylene copolymer, which comprises polymerizing at a pm (weight basis) or less. 7. When copolymerizing formaldehyde cyclic oligomer or cyclic acetal as a main monomer in the presence of a comonomer which can be copolymerized with the main monomer,
Perfluoroalkylsulfonic acid or a perfluoroalkylsulfonic acid derivative is used as a polymerization catalyst in the range of 1 × 10 ⁻⁶ to 2 × 10 ⁻⁵ mol% with respect to the main monomer, and the water content and formic acid in all the monomers are used. 40p each
Polymerization at pm (weight basis) or less, and further in deactivating the polymerization catalyst in the obtained polymer, a. An ion adsorbent containing, as a main component, at least two oxides of at least one selected from oxides of alkali metals and alkaline earth metals and at least one selected from oxides of trivalent and tetravalent elements. Or b. General formula M1 _1-x M2 _x (OH) _{2 An} ^- _{x / n} · mH ₂ O (wherein M1 represents at least one divalent metal selected from alkaline earth metals, and M2 is trivalent) Showing metal,
A ^n- represents an n-valent anion. Also, x is 0 <x ≦ 0.5.
And m is a positive number. ) Ion adsorbent represented by. At least one selected from the group consisting of 0.
A method for producing a polyoxymethylene copolymer composition, characterized in that 001 to 0.5 wt% is added and melt-mixed.