JPS6153367B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyacetal copolymer, and more specifically, the present invention relates to a method for producing a polyacetal copolymer.

The present invention relates to a method of copolymerizing [Formula] in an organic medium containing a molecular weight regulator in the presence of an anionic polymerization catalyst excluding a tetravalent organotin compound and a polyvalent metal chelate compound and a Lewis acid. Japanese Patent Publication No. 42-15632 discloses that formaldehyde and 1.3
- There is a description that it is copolymerized with dioxepane. Further, Japanese Patent Publication No. 48-3558 describes the copolymerization of formaldehyde and cyclic ether using a reaction mixture of a polyvalent metal chelate compound and a Lewis acid. When formaldehyde copolymers are produced using catalysts that are essentially Lewis acids, there are disadvantages in that side effects frequently occur and the molecular weight of the copolymers decreases. Industrially, it is necessary to produce a copolymer having a predetermined molecular weight by using a so-called molecular weight regulator. In these methods the use of molecular weight regulators is not possible and these methods are not necessarily suitable industrial methods. On the other hand, when an anionic polymerization catalyst having formaldehyde homopolymerization activity is used, formaldehyde and 1,3-dioxepane do not react and no copolymer is obtained. As mentioned above, it is difficult to obtain a polyacetal copolymer having performance as an engineering plastic using a Lewis acid alone or an anionic polymerization catalyst alone. As a result of extensive studies on the copolymerization reaction of formaldehyde, the present inventors found that formaldehyde and 1.3
- It has been discovered that a polyacetal copolymer having both good thermal stability and a desired molecular weight can be obtained in high yield by copolymerizing dioxepane in an organic medium containing a molecular weight regulator, and the present invention has been made based on this discovery. I was able to complete it. That is, the present invention is a method for producing a polyacetal copolymer by copolymerizing formaldehyde and 1,3-dioxepane in the presence of an anionic polymerization catalyst and a Lewis acid in an organic medium containing a molecular weight regulator. Polymerization catalysts that can be used in the present invention are generally known as formaldehyde anionic polymerization catalysts and coordination anionic polymerization catalysts.
(1) Alkali metals and alkali metal complex compounds, (2) alkali metal alkoxides, (3) alkali metal salts of carboxylic acids and alkaline earth metal salts of carboxylic acids, (4)
Examples include amines, (5) quaternary ammonium salts, (6) quaternary phosphonium salts, and (7) organic metals. Examples of alkali metals include lithium, sodium, potassium, rubidium, and cesium, and examples of alkali metal complex compounds include lithium and cesium.
Examples include anthracene, sodium/naphthalene, sodium/fluorene, potassium/naphthalene, etc. The alkali metal alkoxide is ROM (R:
Represented by C ₁ to C ₁₀ linear or branched alkyl group, M: alkali metal), lithium mate oxide,
Examples include aliphatic alkoxides such as lithium tert-butoxide, sodium ethoxide, sodium propoxide, and potassium octoxide, and aromatic alkoxides such as sodium benzyl alkoxide. The alkali metal carboxylic acid salt is RCOOM (R:
_C1 to _C20 linear or branched alkyl group, M: alkali metal), aliphatic carboxylates such as sodium formate, lithium acetate, potassium propionate, sodium laurate, sodium benzoate, etc. Examples include aromatic carboxylates. In addition, the carboxylic acid alkaline earth metal salt is
(RCOO) ₂ Represented by M′ (R: C ₁ to C ₂₀ linear, branched alkyl group, M′: alkaline earth metal),
Examples include magnesium formate, beryllium acetate, calcium propionate, magnesium laurate, and calcium stearate. Examples of amines include primary amines, secondary amines, and tertiary amines. The primary amine is
RNH ₂ (R: C ₁ to C ₂₀ straight chain, branched alkyl group), monoethylamine, mono-tert
-butylamine, monooctylamine, etc. The secondary amine is represented by R ₂ NH (R: C ₁ to _{C 20} linear/branched alkyl group), and includes diethylamine, di-n-butylamine, dioctylamine, and the like. The tertiary amine is R ₃ N (R: C ₁ ~
( _C20 linear/branched alkyl group), trimethylamine, triethylamine, tri-tert
-butylamine etc., and pyridine etc. are also included in the tertiary amines. Quaternary ammonium salts include NH ₄ X and
R ₁ R ₂ R ₃ R ₄ NX (R ₁ , R ₂ , R ₃ , R ₄ : alkyl group,
Substituted alkyl group, aryl group, substituted aryl group,
There are no restrictions on the combinations. X:25
℃, anion obtained by removing hydrogen ions from a Lewis acid with a dissociation constant of 1 × 10 ^-2 to 1 × 10 ^-16 in water), ammonium laurate, ammonium stearate, Tetramethylammonium propionate, tetrabutylammonium acetate, trioctylbenzylammonium caproate, dimethyldistearylammonium acetate, dimethyldibenzylammonium laurate, tetramethylammonium butoxide, trimethylbenzylammonium propoxide, triphenylmethylammonium butoxide, Examples include tetrabutylammonium hydroxide, dimethyldistearylammonium hydroxide, and tetraethylammonium carboxylate. The quaternary phosphonium salt is R ₁ R ₂ R ₃ R ₄ PX (R ₁ ,
R ₂ , R ₃ , R ₄ : selected from an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, and there are no restrictions on the combination thereof. X: 1×10 ^-2 ~ in water at 25℃
Anion obtained by removing hydrogen ions from a Lewis acid with a dissociation constant of 1×10 ^-16 )
It is represented by tetramethylphosphonium propionate, tetraethylphosphonium laurate,
Examples include tetraphenylphosphonium acetate, triphenylmethylphosphonium acetate, dimethylbenzylphosphonium laurate, tetramethylphosphonium butoxide, tetrabutylphosphonium hydroxide, and tetraethylphosphonium carboxylate. The first group of organometallics is RM (R: C ₁ ~
Represented by C ₅ straight chain, branched alkyl group, M: alkali metal) and R ₂ M′ (R: C ₁ to C ₅ straight chain, branched alkyl group, M′: alkaline earth metal). ,
Examples include methyllithium, n-butyllithium, ses-butyllithium, ethyl sodium, butyl potassium, diethyl calcium, dibutyl strontium, and the like. The second group of organometallics is RMgX′ (R:
It is represented by a C ₁ to C ₅ linear or branched alkyl group, X': halogen), and examples thereof include methylmagnesium chloride, ethylmagnesium bromide, butylmagnesium iodide, and the like. Among these anionic polymerization catalysts, alkali metal complex compounds, amines, quaternary ammonium salts, and organic metals are preferred. The Lewis acids used in the present invention include:
Tin tetrachloride, tin tetrabromide, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate, boron trifluoride dimethyl etherate, So-called Friedel-Crafts type compounds such as boron trifluoride coordination compounds such as boron trifluoride acetic anhydrate and boron trifluoride triethylamine complex, perchloric acid, acetyl perchlorate, hydroxyacetic acid, trichloroacetic acid, P - Inorganic and organic acids such as toluenesulfonic acid, complex salt compounds such as triethyloxonium tetrafluoroborate, triphenylmethylhexachloroantimonate, allyldiazonium hexafluorophosphate, allyldiazonium tetrafluoroborate, diethylzinc, triethylaluminum, Examples include alkyl metals such as diethylaluminum chloride. Molecular weight modifiers that can be used in the present invention include acetal compounds, orthoformates, alcohols, carboxylic acids, carboxylic acid anhydrides, and water. The first group of acetal compounds includes ROCH ₂ OR (R: alkyl group), HOCH ₂ OR
There are formal compounds and hemiformal compounds represented by (R: alkyl group). Specific examples include methylal, ethyral (diethoxymethane), di-n-butoxymethane, butoxyhydroxymethane, and the like. as the second group
There is a polyacetal compound represented by RO(CH ₂ O) _o R (R: alkyl group, n is an integer from 2 to 20). Specific examples include dioxymethylene dimethoxide, tetraoxymethylene diethoxide, decaoxymethylene dimethoxide, and the like. Third
as a class group

There is an acetal compound represented by the formula (R: alkyl group). Specific examples include dimethyl acetal, diethyl acetal (acetal), dibutyl acetal, and the like. Examples of the orthoformate include methyl orthoformate, ethyl orthoformate, butyl orthoformate, and the like. Examples of the alcohol include aliphatic alcohols such as methanol, ethanol, n-propanol, n-butanol, and stearyl alcohol, and aromatic alcohols such as benzyl alcohol. Examples of carboxylic acids include aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, and lauric acid, and aromatic carboxylic acids such as benzoic acid. Examples of the carboxylic anhydride include aliphatic carboxylic anhydrides such as acetic anhydride, propionic anhydride, succinic anhydride, and maleic anhydride, and aromatic carboxylic anhydrides such as phthalic anhydride. Among these molecular weight regulators, formal compounds represented by ROCH ₂ OR,
A polyacetal compound represented by RO(CH ₂ O) _o R,

An acetal compound represented by the formula is preferred, and methylal and diethyl acetal are particularly preferred because of ease of purification and availability. Organic media that can be used in the present invention include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane, benzene, toluene,
Aromatic hydrocarbons such as xylene, chloroform,
Examples include halogenated hydrocarbons such as carbon tetrachloride, and ether compounds such as ethyl ether and dioxane. The formaldehyde used in the present invention must be substantially anhydrous and must be purified using a known method such as a cold trap method or a solvent washing method. Furthermore, 1,3-dioxepane must be substantially anhydrous and should be purified by distillation or adsorption. For producing the polyacetal copolymer of the present invention,
Any polymerization method known as a method for homopolymerizing formaldehyde, such as a blow polymerization method or a solution polymerization method, can be used. The blow polymerization method is a method in which formaldehyde gas is directly blown into an organic medium containing 1,3-dioxepane, a molecular weight regulator, an anionic polymerization catalyst, and a Lewis acid. In the solution polymerization method, an organic medium containing 1,3-dioxepane and a molecular weight regulator is cooled, formaldehyde gas is absorbed into this solution, and then an anionic polymerization catalyst and a Lewis acid are simultaneously added to start copolymerization. It's a method. The ratio of 1,3-dioxepane to formaldehyde during the copolymerization reaction is from 0.05 to 100 mol%, particularly preferably from 0.2 to 30 mol%. 1,3-dioxepane is used by uniformly dissolving or dispersing it in an organic medium. _gr/ ) t: Copolymerization reaction temperature (°C) If the concentration is maintained below the concentration (M) specified by the formula, particularly excellent results can be obtained in terms of thermal stability, base stability, etc. . The anionic polymerization catalyst has a concentration in the organic medium of 1 x 10 ^-8 to 1 x 10 ^-2 mol/, more preferably 5
It is used in the range of ×10 ^-8 to 3 ×10 ^-3 mol/. Also, the Lewis acid has a concentration of 1 in an organic medium.
×10 ^-7 to 5 × 10 ^-2 mol/, more preferably 1 ×
It is used in a range of 10 ^-6 to 5 x 10 ^-3 mol/. It is desirable that the anionic polymerization catalyst and Lewis acid are introduced separately into an organic medium and then mixed in the organic medium. It is a surprising phenomenon that an anionic polymerization catalyst and a Lewis acid exhibit copolymerization activity without being deactivated even when they coexist in an organic medium. The copolymerization reaction temperature is usually set at -40 to 118°C, but is more preferably set in relation to the 1,3-dioxepane concentration in the organic medium, as shown in the above-mentioned formula. There is no particular limit on the reaction time, but 5
It is set in the range of ~400 minutes. The molecular weight regulator is used after being uniformly dissolved or dispersed in an organic medium. The concentration of the molecular weight modifier in the organic medium can be readily determined experimentally depending on the molecular weight requirements of the desired copolymer. Next, these copolymers are usually separated from the organic medium and then stabilized by heating with a basic substance such as amine or NaOH in water or alcohol. The stabilized copolymer is then added with a stabilizer and the like, and put into practical use. As described in detail above, by using the production method of the present invention, it has become possible to obtain a good copolymer. The features of the present invention are listed below. (1) The copolymer must have good thermal stability. (2) The copolymer exhibits excellent stability against basic substances. (3) The molecular weight of the copolymer can be controlled arbitrarily. In the following description, the reduced viscosity is measured at 60 DEG C. in p-chlorophenol-tetrachlorethylene (1:1) solution at a concentration of 0.5 gr/dl. The melting point is a value measured using the D・S・C method at a heating rate of 16° C./min. Base stability was measured by the yield (base stabilization yield) when heat treated at 140° C. for 60 minutes in a benzyl alcohol solution containing 1% tributylamine. K ₂₂₂ (%/min) is the thermal decomposition rate constant of the polymer at 222°C under vacuum. The present invention will be explained below with reference to Examples, but these are not intended to limit the scope of the present invention. Example 1 Thoroughly dehydrated and dried paraformaldehyde
Formaldehyde gas with a purity of 99.9% was obtained by thermal decomposition in a temperature range of 135°C to 145°C and passing through a cooling trap 5 times. 100 parts per hour of formaldehyde gas, 68 gr/ of 1,3-dioxepane, 1.0 x 10 ^-4 mol/ of trimethylbenzylammonium acetate, 1.0 x 10 ^-4 mol/ of boron trifluoride diethyl etherate and molecular weight adjustment. The mixture was introduced into 400 parts of n-hexane containing 0.33 gr/methylal as agent. Simultaneously with the introduction of formaldehyde, 68 gr/ of 1,3-dioxepane, 1.0 x 10 ^-4 mol/ of trimethylbenzylammonium acetate, 1.0 x 10 ^-4 mol/ of boron trifluoride diethyl etherate and 0.33 gr/ of methylal were introduced. Contains n-hexane per hour
Feeding was started at a rate of 400 parts and continued for 3 hours. Formaldehyde gas was also continuously supplied for 3 hours at a rate of 100 parts per hour.
During this time, the polymerization temperature was maintained at 55°C. The n-hexane containing the copolymer was continuously withdrawn in proportion to the feed, and the copolymer was separated by filtration. After thoroughly washing the copolymer with acetone, vacuum drying at 60℃,
295 parts of white polymer were obtained. This polymer had a reduced viscosity of 2.10 and a melting point of 165°C. In addition, the base stabilization yield of this polymer was as high as 98.5%, and the K ₂₂₂ after base stabilization was as good as 0.02%/min, making it possible to obtain a polymer with excellent thermal stability and base stability. Ta. Furthermore, when a stabilizer was added to this polymer and the polymer was subjected to molding, a good molded product could be obtained. Examples 2-13 Formaldehyde gas with a purity of 99.9% is added at a rate of 100 parts per hour to 400 parts of cyclohexane containing 1,3-dioxepane, a polymerization catalyst, a Lewis acid and a molecular weight regulator as shown in Table 1. It was fed continuously for 3 hours. 1,3-Dioxepane and the polymerization catalyst shown in Table 1 were also continuously fed for 3 hours at a rate of 400 parts per hour. The polymerization temperature was maintained at the temperatures shown in Table 1. After separating the copolymer from the organic medium, the same procedure as in Example 1 was carried out, and the results are shown in Table 1. It is clear from Table 1 that in all Examples, polymers with excellent thermal stability and base stability were obtained in high yields. Comparative Example 1 Among the reagents used in Example 1, only trimethylbenzylammonium acetate was excluded, and all the others were operated in the same manner as in Example 1. The results are shown in Table 1. As is clear from Table 1, only a polymer with low reduced viscosity and poor thermal stability was obtained. Comparative Example 2 Among the reagents used in Example 1, only boron trifluoride diethyl etherate was excluded, and all others were operated in the same manner as in Example 1. The results are shown in Table 1. As is clear from Table 1, only a polymer with an extremely low base-stabilized yield was obtained. Comparative Example 3 Among the reagents used in Example 1, only methylal, which is a molecular weight regulator, was excluded, and all others were operated in the same manner as in Example 1. The results are shown in Table 1.
As is clear from Table 1, the base stabilization yield was poorer than in Example 1. We also attempted to mold this polymer after adding a stabilizer to it, but due to its high viscosity,
A good molded product could not be obtained. Example 14 250 parts of formaldehyde with a purity of 99.9% was added to 19gr/
An absorption liquid was prepared by blowing into 750 parts of benzene containing 1,3-dioxepane and 0.58 gr/methylal. Trimethylbenzylammonium acetate and boron trifluoride diethyl etherate were added to this absorption liquid to initiate the polymerization. The polymerization temperature was maintained at -16°C. Two hours after the start of the polymerization, 50 parts of a 5% acetone solution of tributylamine was added to stop the polymerization. After separating the copolymer, it was thoroughly washed with acetone and vacuum dried to obtain 245 parts of a white polymer. This polymer had a reduced viscosity of 1.75 and a melting point of 166°C. Additionally, the base stabilization yield of this polymer is 97.8
% and the K ₂₂₂ of the polymer after base stabilization is 0.03
%/min, and a polymer with excellent thermal stability and base stability could be obtained.

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Claims (1)

[Scope of Claims] 1. Formaldehyde and 1,3-dioxepane are mixed in an organic medium containing a molecular weight regulator in the coexistence of an anionic polymerization catalyst excluding a tetravalent organotin compound and a polyvalent metal chelate compound and a Lewis acid. A method for producing a polyacetal copolymer, characterized by copolymerizing inside a polyacetal copolymer. 2 The concentration of 1,3-dioxepane in the organic medium is defined as: M=0.81t+32.6 M: 1,3-dioxepane concentration (gr/) t: Copolymerization reaction temperature (℃) Concentration (M) The manufacturing method according to claim 1, characterized in that: 3. The method according to claim 1, wherein the polymerization catalyst is a compound selected from the group consisting of an alkali metal complex compound, an amine, a quaternary ammonium salt, and an organic metal. 4 The molecular weight regulator is ROCH ₂ OR (R: alkyl group), RO (CH ₂ O) _o R (R: alkyl group, n=2
20) and an acetal compound represented by the formula (R: alkyl group). 5. The method according to claim 4, wherein the acetal compound is methylal or diethyl acetal.