JPS6210527B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyacetal copolymer, and more specifically to a method for copolymerizing formaldehyde with a polycyclic formal in the coexistence of an anionic polymerization catalyst and a Lewis acid. Japanese Patent Publication No. 42-15632 describes the copolymerization of formaldehyde and 1,4-butanediol formal using a catalyst mainly containing boron trifluoride. Furthermore, Japanese Patent Publication No. 43-22871 discloses a method for copolymerizing formaldehyde and cyclic formal using an acidic catalyst, and Japanese Patent Publication No. 48-3558 discloses a method for copolymerizing formaldehyde and cyclic formal using a reaction mixture of a polyvalent metal chelate compound and a Lewis acid. is stated. The catalysts found in these publications are essentially Lewis acids, and the production of formaldehyde copolymers using Lewis acid catalysts has the disadvantage that side reactions occur frequently and the molecular weight of the copolymers decreases. Japanese Patent Publication No. 43-26872 describes a method of reacting polyoxymethylene with dioxolane or polydioxolane in an acidic medium. Even in this method, the molecular weight decreases significantly due to the use of an acidic catalyst. On the other hand, when an anionic polymerization catalyst having formaldehyde homopolymerization activity is used, formaldehyde does not react with cyclic formal or polycyclic formal, and no copolymer is obtained. As a result of extensive studies on the production method of polyacetal copolymers, the present inventors found that copolymerization of formaldehyde and polycyclic formal in the coexistence of an anionic polymerization catalyst and a Lewis acid achieves the desired molecular weight and good thermal stability. - It was discovered that a polyacetal copolymer having both base stability and base stability can be obtained in high yield, leading to the completion of the present invention. That is, an object of the present invention is to provide a method for producing a polyacetal copolymer having a desired molecular weight and excellent physical properties by introducing an oxyalkylene group into a polyoxymethylene main chain. In the present invention, the general formula −[(CH ₂ ) _n OCH ₂ O−] _o (m
=2, 3, 4, 5, 6, 7, 8, 10, n=3~
20000) and general formula − [(CH ₂ CH ₂ O) _n CH ₂ O−] _o (m
= 2 to 15, n = 3 to 20000) can be used as a comonomer. Polycyclic formals are usually the corresponding cyclic alkylene glycol formals

[Formula] and cyclic polyethylene glycol formal

Obtained by cationic ring-opening polymerization of [Formula]. Examples of polycyclic formals include poly(ethylene glycol formal), poly(1,3-propanediol formal), poly(1,4-butanediol formal), poly(1,5-pentanediol formal), and poly(1,5-pentanediol formal). 6-hexanediol formal), poly(1,7-heptanediol formal), poly(1,8-octanediol formal), poly(1,10-decanediol formal), poly(diethylene glycol formal), poly(triethylene These include poly(glycol formal), poly(tetraethylene glycol formal), poly(hexaethylene glycol formal), and poly(polyethylene glycol-200 formal). In addition, in the present invention, the general formula

A polycyclic formal having a structure represented by the formula (R=alkyl group, aryl (a1, y1) group, n=3 to 20000) can also be used as a comonomer. This cyclic formal is usually the corresponding 3-alkyl-1,3-dioxolane.

Obtained by cationic ring-opening polymerization of [Formula], for example, poly(propylene glycol formal), poly(butylene glycol formal), poly(styrene glycol formal)
etc. In addition to these polycyclic formals, ring-opening polymers of cyclic formals other than those mentioned above, such as poly(2,3-butanediol formal) and poly(cyclohexanediol formal), can also be used as comonomers. Among these polycyclic formals, poly(ethylene glycol formal), poly(1,4-butanediol formal), poly(1,5-pentanediol formal), poly(1,6-hexanediol formal), poly (diethylene glycol formal), poly(triethylene glycol formal) and poly(tetraethylene glycol formal) are preferred. Also, the average degree of polymerization (n) of polycyclic formal
is required to be between 3 and 20,000, but the lower limit of the average degree of polymerization is more preferably 5 or more from the viewpoint of avoiding chain transfer reactions during copolymerization reactions as much as possible. The upper limit is more preferably 5000 or less from the viewpoint of ease of synthesis. These polycyclic formals are used alone or in combination for the reaction. Further, prior to the reaction, it is preferable to purify the polycyclic formal by removing impurities such as water contained in the polycyclic formal as much as possible. The anionic polymerization catalyst that can be used in the present invention generally has formaldehyde homopolymerization activity. These anionic polymerization catalysts include alkali metals, alkali metal complex compounds, alkali metal alkoxides, alkali metal carboxylates, alkaline earth metal carboxylates, amines,
Quaternary ammonium salt, quaternary phosphonium salt,
Examples include organic metals and tetravalent organic tin compounds. Examples of alkal metals include sodium and potassium, which are usually used after being dispersed in an organic medium. Examples of the alkali metal complex compounds include complex compounds of alkali metals and aromatic hydrocarbons, such as sodium-naphthalene and potassium-anthracene. The alkali metal alkoxide is ROM (R=C ₁
~ _C10 linear/branched alkyl group, M=alkali metal), and examples include sodium methoxide, potassium t-butoxide, and potassium octoxide. The alkali metal carboxylic acid salt is RCOOM (R=
It is a compound represented by a _C5 to _C20 linear or branched alkyl group (M=alkali metal), and examples include sodium caproate, potassium laurate, and cesium stearate. Carboxylic acid alkaline earth metal salts are
(RCOO) is a compound represented by ₂ M′ (R= _C5 to _C20 linear/branched alkyl group, M′=alkaline earth metal), and includes magnesium 2-ethylhexanoate, calcium laurate, calcium stearate, Examples include strontium stearate. Examples of amines include primary amines represented by RNH ₂ (R is a C ₁ to C ₂₀ linear/branched alkyl group);
R ₂ NH (R is a C ₁ to C ₂₀ linear/branched alkyl group)
and tertiary amines represented by R ₃ N (R is a C ₁ to C ₂₀ linear or branched alkyl group). For example, ethylamine, n-butylamine, octylamine, stearylamine, di-n-propylamine, di-t-butylamine,
Distearylamine, triethylamine, tri-
Examples include n-butylamine, trioctylamine, diethylbenzylamine, and the like. Further, cyclic amines such as pyridine can also be used. The quaternary ammonium salt is NH ₄ X or
R ₁ R ₂ R ₃ R ₄ NX (R ₁ , R ₂ , R ₃ , R ₄ = hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group, and there are no restrictions on the combination.
= anion obtained by removing hydrogen ions from a Lewis acid having a dissociation constant of 1 x 10 ^-2 to 1 x 10 ^-16 in water at 25°C. For example, ammonium laurate, ammonium stearate, tetramethylammonium propionate, tetrabutylammonium caproate, trioctylbenzylammonium acetate, dimethyldistearic ammonium propionate, diethyldibenzylammonium laurate, tetramethylammonium methoxide, trimethylbenzylammonium propoxide, triphenylmethylammonium butoxide, tetrabutylammonium hydroxide,
Examples of quaternary ammonium salts include dimethyl distearylammonium 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 hydrogen, 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=25℃, 1× in water
It is a compound represented by an anion obtained by removing hydrogen ions from a Lewis acid having a dissociation constant of 10 ^-2 to 1 x 10 ^-16 . For example, tetraethylphosphonium propionate, tetrabutylphosphonium acetate, tetraoctylphosphonium caproate, triphenylmethylphosphonium propionate, tetrabutylphosphonium ethoxide, triethylbenzylphosphonium butoxide, tetraoctylphosphonium hydroxide, tetraethylphosphonium carboxylate, etc. It is listed as a quaternary phosphonium salt. The first group of organometallics is RM (R=C ₁ ~
It is a compound represented by C ₁₀ linear or branched alkyl group, M = alkali metal) or R ₂ M′ (R = C ₁ to _{C 10} linear or branched alkyl group, M′ = alkaline earth metal). , methyllithium, n-butyllithium, ethyl sodium, sec-butylpotassium, diethylcalcium, dioctylstrontium, and the like. The second group of organometallics is RMgX′ (R=
It is a compound represented by a C ₁ to C ₈ linear or branched alkyl group, X' = halogen, and examples include methylmagnesium chloride, ethylmagnesium bromide, butylmagnesium iodine, and the like. The tetravalent organic tin compound is a compound represented by R _1n S _o X _4-n . Here, n = an integer of 1 to 3, and R ₁ = selected from an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, each of which may be the same or different. X = halogen, -
OH, −OR ₂ ,

Selected from [Formula] (R ₂ = C ₁ to C ₂₀ linear/branched alkyl group). Examples include tin trichloride, ethyltin triacetate, butyltin trimethoxide, dimethyltin dibromide, diisopropyltin dilaurate, dioctyltin dibutoxide, dibutyltin hydroxystearate, dioctyltin dilaurate, triethyltin ethoxide, tributyltin stearate, and the like. 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 acetic anhide esters, so-called Friedel-Crafts type compounds such as boron trifluoride coordination compounds such as boron trifluoride triethylamine complex compounds, inorganic compounds such as perchloric acid, acetyl perchlorate, hydroxyacetic acid, trichloroacetic acid, p-toluenesulfonic acid, etc. Acids and organic acids, complex salt compounds such as triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate, allyldiazonium hexafluorophosphate, allyldiazonium tetrafluoroborate, alkyls such as diethylzinc, triethylaluminum, diethylaluminium chloride, etc. Examples include metals. Among these Lewis acids, Friedel-Crafts type compounds and complex salt compounds are more preferred in terms of activity, but inorganic salts, organic acids, and alkyl metals can also be combined with Friedel-Crafts type compounds by increasing the amount added. It can bring about the same effect as salt compounds. In the present invention, the molecular weight of the polyacetal copolymer can also be arbitrarily adjusted using a molecular weight regulator. Molecular weight modifiers that can be used in the present invention include acetal compounds, orthoformates, alcohols, carboxylic acids, carboxylic acid anhydrides, and water. As the first group of acetal compounds,
ROCH ₂ OR (R = alkyl group), HOCH ₂ OR (R
= a formal compound represented by (alkyl group),
There are hemiformal compounds. Specific examples include methylal, diethoxymethane, di-n-butoxymethane, butoxyhydroxymethane, and the like. The second group of acetal compounds includes RO( _CH2O )nR (R=alkyl group, n=2
There are polyacetal compounds represented by ~20). Specifically, dioxymethylene dimethoxide,
Examples include tetraoxymethylene diethoxide and decaoxymethylene dimethoxide. These compounds are often difficult to isolate as single substances and are usually used as a mixture. The degree of polymerization (n) of these compounds can be determined by nuclear magnetic resonance spectroscopy (NMR), gas chromatography (GC).
), liquid chromatography (LC), and other methods. As a third group of acetal compounds

There is an acetal compound represented by the formula (R=alkyl group).
Specific examples include dimethyl acetal, diethyl acetal, di-t-butyl acetal, dioctyl acetal, and the like. Orthoformic acid ester is HC(OR) ₃ (R=C ₁ ~
It is a compound represented by _C4 straight chain/branched alkyl group and phenyl group), such as methyl orthoformate, ethyl orthoformate, -iso-propyl orthoformate,
Ethylpropyl orthoformate, butyl orthoformate,
Examples include phenyl orthoformate. Alcohol is a compound represented by ROH (R=C ₁ to C ₂₀ linear/branched alkyl group, aryl group), and includes fatty acids such as methanol, ethanol, n-propanol, n-butanol, lauryl alcohol, and stearyl alcohol. Examples include aromatic alcohols such as group alcohols, benzyl alcohol, and 2-phenylethanol. Carboxylic acids are RCOOH (R = hydrogen, C ₁ - C ₂₀
It is a compound represented by linear/branched alkyl groups, aryl groups), and is a compound represented by formic acid, acetic acid, propionic acid,
Examples include aliphatic carboxylic acids such as lauric acid and stearic acid, and aromatic carboxylic acids such as benzoic acid and iso-phthalic acid. Carboxylic acid anhydride is

【formula】 【formula】

【formula】

[Formula] (R=C ₁ to C ₂₀ alkyl group, R ₂ = hydrogen or C ₁ to C ₈ alkyl group, R ₃
= hydrogen or C ₁ to C ₈ alkyl group), and aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, stearic anhydride, succinic anhydride, dodecenylsuccinic anhydride, maleic anhydride, Examples include aromatic carboxylic anhydrides such as phthalic anhydride and 4-methylphthalic anhydride. Among these molecular weight regulators, from the viewpoint of improving the thermal stability and base stability of the polymer, RO・
Formal compound represented by CH ₂ OR, RO
Polyacetal compounds represented by (CH ₂ O) nR and

An acetal compound represented by the formula is preferable, and moreover, from the viewpoint of ease of purification and availability,
Methyral and diethyl acetal are particularly preferred. The copolymerization according to the invention is usually carried out in an organic medium. 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, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, halogenated aromatics such as chlorobenzene, o-dichlorobenzene, α-chloronaphthalene, etc. Examples include hydrocarbons. These organic media may be used alone or in combination of two or more. 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. For producing the polyacetal copolymer of the present invention,
As a method for homopolymerizing formaldehyde, both the blow polymerization method and the 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 a polycyclic formal, a molecular weight regulator when a molecular weight regulator is used, an anionic polymerization catalyst, and a Lewis acid.
The solution polymerization method is to cool an organic medium containing a polycyclic formal and a molecular weight regulator when using a molecular weight regulator, and to absorb formaldehyde into this solution, and then add an anionic polymerization catalyst and a Lewis acid at the same time. This is a method of starting copolymerization. The polycyclic formal is preferably 0.01 to 100 parts by weight, more preferably
0.1 to 50 parts by weight are used. 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 a range of ×10 ^-8 to 5 ×10 ^-3 mol/.
Also, the Lewis acid has a concentration of 1× in the organic medium.
10 ⁻⁷ to 5×10 ⁻² mol/, more preferably 1×
It is used in a range of 10 ^-5 to 5 x 10 ^-3 mol/. It is preferable that the anionic polymerization catalyst and Lewis acid are separately supplied into an organic medium and then mixed in the organic medium. It is truly a surprising phenomenon that even when an anionic polymerization catalyst and a Lewis acid coexist in an organic medium, they do not become deactivated and exhibit copolymerization activity. The copolymerization reaction temperature is usually set at -40 to 118°C. Further, there is no particular restriction on the reaction time, but it is set within a range of 5 to 400 minutes. When a molecular weight regulator is used, the molecular weight regulator is used after being uniformly dissolved or dispersed in an organic medium, similar to the polycyclic formal. The concentration of the molecular weight modifier in the organic medium can be easily determined experimentally depending on the molecular weight requirements of the desired copolymer. After the copolymerization reaction is completed, the copolymer is usually separated from the organic medium, and water and alcohol are added together with a basic substance such as an amine and sodium hydroxide, followed by heating and stabilization. A stabilizer and the like are then added to the stabilized copolymer, and the copolymer is put into practical use. By using the production method of the present invention described in detail above, it has become possible to obtain a good polyacetal copolymer. The features of the present invention are listed below. (1) It is possible to produce polyacetal copolymers with excellent thermal stability and base stability. (2) The molecular weight of the polyacetal copolymer can be arbitrarily controlled by using a molecular weight regulator. (3) By using a specific molecular weight regulator, it is possible to improve the thermal stability and base stability of the polymer at the same time as using the molecular weight regulator. In the following description, reduced viscosity is a value measured at 60°C in a p-chlorophenol-tetrachlorethylene (1:1 weight ratio) solution at a polymer concentration of 0.5 gr./dl, and is It is a measure. The base stabilization yield is the recovery rate of the polymer when heated at 140°C for 60 minutes at a polymer concentration of 5% in a benzyl alcohol solution containing 1% tributylamine. It is a measure of gender. K ₂₂₂ is the thermal decomposition rate constant of a polymer at 222°C under vacuum and is a measure of the thermal stability of the polymer. 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 the temperature range of 135°C to 145°C and passing through a cooling trap several times. 125 parts (parts by weight) of formaldehyde gas per hour were mixed with 16 gr./poly(1,4-butanediol formal) (average molecular weight 4500), 1×10 ^-4 mol./
n-butyllithium, 1×10 ^-4 mol./boron trifluoride triethylamine complex and 0.08 gr./methylal as molecular weight regulator.
It was introduced into 500 parts of n-hexane. At the same time as formaldehyde gas was supplied, 16gr./poly(1,4-butanediol formal) (average molecular weight 4500), 1×10 ^-4 mol./n-butyllithium, 1×10 ^-4 mol./ Boron trifluoride triethylamine complex and n-hexane containing 0.08 gr./methylal were continuously fed at a rate of 500 parts per hour for 3 hours. Formaldehyde gas is also 1
Supplied continuously for 3 hours at a rate of 125 parts per hour,
During this time, the polymerization temperature was maintained at 48°C. N-hexane containing the copolymer was continuously extracted in proportion to the amount supplied, and the copolymer was separated by filtration. After thoroughly washing the copolymer with acetone, vacuum drying at 60℃,
340 parts of white polymer were obtained. This polymer had a reduced viscosity of 1.78 and a base stabilization yield of 96.6%. Furthermore, the K ₂₂₂ of the polymer after base stabilization was as good as 0.03%/min, and a polymer having the desired molecular weight and excellent thermal stability and base stability could be obtained in high yield. Examples 2 to 10 Formaldehyde gas with a purity of 99.9% was mixed with polycyclic formal shown in Table 1 at a rate of 100 parts per hour, an anionic polymerization catalyst, a Lewis acid, and toluene containing a molecular weight regulator when controlling the molecular weight.
It was continuously fed into 500 parts for 3 hours. Cyclic formals, anionic polymerization catalysts, Lewis acids, and toluene containing a molecular weight regulator in Table 1 are also supplied at a rate of 500 parts per hour for 3 hours continuously in the same way as the formaldehyde gas, and the copolymerization temperature is During this period, the temperature shown in Table 1 was maintained. After separating the copolymer from toluene, it was operated in the same manner as in Example 1, and the results are also shown in Table 1. It is clear that in all of the examples, copolymers with excellent thermal stability and base stability and with the desired molecular weight could be obtained in high yields when a molecular weight regulator was used. Comparative Example 1 Among the reagents used in Example 1, only n-butyllithium was excluded, and all other operations were performed in the same manner as in Example 1, and 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 the boron trifluoride triethylamine complex was excluded, and all other operations were performed in the same manner as in Example 1, and the results are shown in Table 1.
As is clear from Table 1, most of the produced polymers were formaldehyde homopolymers, and the base stabilization yield was poor.

【table】

【table】

Claims (1)

[Claims] 1 Formaldehyde and the general formula −[(CH ₂ ) _n OCH ₂ O−] _o (m=2, 3, 4, 5,
6, 7, 8, 10, n = 3 ~ 20000) and general formula - [(CH ₂ CH ₂ O) _n CH ₂ O -] _o (m = 2 ~ 15, n = 3
A method for producing a polyacetal copolymer, which comprises copolymerizing a compound selected from polycyclic formals having a structure represented by 1 to 20,000) in the coexistence of an anionic polymerization catalyst and a Lewis acid. 2 A compound in which the polycyclic formal is selected from poly(ethylene glycol formal), poly(1,4-butanediol formal), poly(1,5-pentanediol formal), and poly(1,6-hexanediol formal) The manufacturing method according to claim 1. 3. The manufacturing method according to claim 1, wherein the polycyclic formal is a compound selected from poly(diethylene glycol formal), poly(triethylene glycol formal), and poly(tetraethylene glycol formal). 4 The average degree of polymerization (n) of the polycyclic formal is
5 to 5,000. The manufacturing method according to any one of claims 1 to 3. 5. The production method according to claim 1, in which a molecular weight regulator is present during the copolymerization reaction. 6 The molecular weight regulator has the general formula ROCH ₂ OR (R = alkyl group), RO (CH ₂ O) _o R (R = alkyl group, n
2-20) and the acetal compound represented by the formula (R=alkyl group). 7. The production method according to claim 6, wherein the acetal compound is methylal or diethyl acetal. 8. The production method according to claim 1, wherein the copolymerization reaction is carried out in an organic medium.