JPS6153369B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing thermally stable polyoxymethylene. More specifically, a method for producing stabilized polyoxymethylene with excellent thermal stability and base stability by reacting polyoxymethylene with a number average molecular weight of 10,000 or more and polyalkylene oxide in the presence of a Lewis acid. It is related to. Japanese Patent Publication No. 43-26872 describes a method of reacting polyoxymethylene with 1,3-dioxolane, and Japanese Patent Publication No. 48-3711 describes a method of reacting polyoxymethylene with 1,3,6-trioxokene. A method is described. In these methods, side reactions frequently occur and the main chain of polyoxymethylene is cleaved, making it difficult to obtain stabilized polyoxymethylene with a constant molecular weight. Japanese Patent Publication No. 44-27667 discloses a method of reacting polyoxymethylene with a cyclic ether, but the cyclic ether has relatively low reactivity, and an excessive amount of the cyclic ether must be used. Further, Japanese Patent Publication No. 52-9230 describes that polyoxymethylene is reacted with ethylene glycol or diethylene glycol. In this method, the reaction produces a large amount of water. The water produced acts as a chain transfer agent before being removed from the system.
Lowers the molecular weight of the polymer. In addition, this method also makes it difficult to control the reaction. As a result of extensive studies on the stabilization reaction of polyoxymethylene, the present inventors found that when polyoxymethylene and polyalkylene oxide are reacted in the presence of a Lewis acid, a stable product with good physical properties and a desired molecular weight can be obtained. The present inventors have discovered that polyoxymethylene can be obtained in high yield, and have completed the present invention. That is, the first object of the present invention is to provide a method for producing stabilized polyoxymethylene having a desired molecular weight and excellent thermal stability and base stability by inserting an oxyalkylene bond into the main chain of polyoxymethylene. It is about providing. A second object of the present invention is to simultaneously provide a production method in which the molecular weight of the polymer is less reduced during the reaction. The polyoxymethylene used in the present invention is a polymer having repeating oxymethylene units (-CH ₂ O-), and is a polymer in which both ends of the polymer are hydroxyl groups, or one or both ends of the polymer are This is a polymer blocked using a known method. Esterification methods, urethanization methods, etherification methods, and the like are known as methods for blocking polymer terminals. In addition, the molecular weight (number average molecular weight) of polyoxymethylene used as a starting material is at least
It is necessary that it is 10,000 or more, but it is more preferably 30,000 or more in view of the practical performance of the stabilized polyoxymethylene. The upper limit of the molecular weight is mainly determined by the desired molecular weight of the stabilized polyoxymethylene and, if a molecular weight regulator is used, the amount of the molecular weight regulator used, but it is more preferably 500,000 or less. In the present invention, the general formula

[Formula] (R = selected from hydrogen, alkyl group, substituted alkyl group, aryl group, and substituted aryl group, each of which may be the same or different. m = 2 to 6, n =
A polyalkylene oxide having a structure represented by 3 to 20,000) can be used. Polyalkylene oxides are usually the corresponding alkylene oxides

Obtained by ring-opening polymerization of [Formula]. As ring-opening polymerization catalysts, cationic polymerization catalysts, anionic polymerization catalysts, coordination anionic polymerization catalysts, and the like are known. The first group of polyalkylene oxides includes polyethylene oxide, which is a ring-opened polymer of ethylene oxide, and polyethylene oxide derivatives. For example, polyethylene glycol (average molecular weight 1500), polyethylene glycol diacetate (average molecular weight 10000), polyethylene glycol dimethyl ether (average molecular weight 15000), glycerin ethylene oxide adduct (average molecular weight
5200), trimethylolpropane ethylene oxide adduct (average molecular weight 920), sorbitan monolaurate ethylene oxide adduct (average molecular weight
2350), pentaerythritol ethylene oxide adduct (average molecular weight 3400), polyethylene oxide (PEO, average molecular weight 50000), polyethylene oxide (PEO, average molecular weight 400000), etc. The second group of polyalkylene oxides includes polypropylene oxide, which is a ring-opened polymer of propylene oxide, and polypropylene oxide derivatives. For example, polypropylene glycol monolaurate (average molecular weight 15000), polypropylene glycol dimethyl ether (average molecular weight 6000), trimethylolpropane propylene oxide adduct (average molecular weight 7150), pentaerythritol propylene oxide adduct (average molecular weight
1150), polypropylene oxide (PPO, average molecular weight 100,000), etc. are included in this group. A third group of polyalkylene oxides includes polybutylene oxide, which is a ring-opened polymer of butylene oxide, and polybutylene oxide derivatives. For example, polybutylene glycol (average molecular weight 2000), polybutylene glycol dipropionate (average molecular weight 4300), polybutylene glycol dimethyl ether (average molecular weight 1000), etc. are included in this group. The fourth group of polyalkylene oxides includes oxetanes, polytrimethylene oxides which are ring-opening polymers of substituted oxetanes, and trimethylene oxide derivatives. For example, trimethylene glycol (average molecular weight 450), trimethylene glycol dimethyl ether (average molecular weight 610), 3.
Ring-opened polymers of 3-bis(chloromethyl)oxetane are included in this group. A fifth group of polyalkylene oxides includes polytetramethylene oxide, which is a ring-opened polymer of tetrahydrofuran. For example, polytetramethylene glycol (average molecular weight 1250), polytetramethylene glycol dimethyl ether (average molecular weight 1750), etc. are included in this group. A sixth group of polyalkylene oxides includes polyhexamethylene oxide, which is a ring-opened polymer of oxepane. For example, polyhexamethylene glycol (average molecular weight 850), polyhexamethylene glycol dimethyl ether (average molecular weight
650) etc. are included in this group. The seventh group of polyalkylene oxides includes styrene oxide, polystyrene oxide, which is a ring-opened polymer of substituted styrene oxide, and polystyrene oxide derivatives. For example, polystyrene glycol (average molecular weight 1850), polystyrene glycol dimethyl ether (average molecular weight
4500), poly p-chlorostyrene glycol (average molecular weight 2750), etc. are included in this group. In addition to the above seven groups, polyalkylene oxides obtained by ring-opening polymerization of alkylene oxides other than the above-mentioned compounds are also effective. For example, a polymer obtained by ring-opening polymerization of epichlorohydrin,
Polymers obtained by ring-opening polymerization of trans-2,3-epoxybutane can also be used in the present invention. Among these polyalkylene oxides, polyethylene oxide, polyethylene oxide derivatives, polypropylene oxide, and polypropylene oxide derivatives are particularly preferred. In addition, the average degree of polymerization (n) of polyalkylene oxide must be between 3 and 20,000,
The lower limit of the average degree of polymerization is preferably 10 or more from the viewpoint of avoiding the generation of water during the reaction, and the upper limit of the average degree of polymerization is more preferably 10,000 or less from the viewpoint of ease of synthesis. In addition, for example, glycerin ethylene oxide adduct When one molecule contains multiple polyalkylene oxide chains, the average degree of polymerization of each polyalkylene oxide chain (n ₁ , n ₂ , n ₃ ......)
It needs to be between 20,000 and even 10~
It is more preferable that it be between 10,000. These polyalkylene oxides alone,
Alternatively, they are mixed and subjected to the reaction. Further, prior to the reaction, it is preferable to purify the polyalkylene oxide by removing impurities such as water contained in the polyalkylene oxide as much as possible. The Lewis acids used in the present invention include:
Tin tetrachloride, tin tetrabromide, titanium tetrachloride, phenyltin trichloride, aluminum trichloride, zinc chloride, vanadium trichloride, phosphorous pentafluoride, antimony trichloride, antimony pentafluoride, boron trifluoride, trifluoride Boron trifluoride coordination compounds such as boron diethyl etherate, boron trifluoride dimethyl etherate, boron trifluoride dioxanate, boron trifluoride acetic anhydrate, boron trifluoride methanolate, boron trifluoride, So-called Friedel-Crafts type compounds such as boron bromide, inorganic and organic acids such as perchloric acid, acetyl perchlorylate, hydroxyacetic acid, trichloroacetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, triphenyl Examples include complex salt compounds such as methylhexafluoroantimonate, allyldiazonium hexachlorophosphate, allyldiazonium tetrafluoroborate, and triethyloxonium tetrafluoroborate, and organoaluminum compounds such as triethylaluminum and diethylaluminum chloride. Among these Lewis acids, Friedel-Crafts type compounds and complex salt compounds are more preferred in terms of activity, but by increasing the amount of inorganic acids and organic acids added, Friedel-Crafts type compounds and complex salt compounds can produce the same effect. In the present invention, the molecular weight of the stabilized polyoxymethylene can 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. The first group of acetal compounds are:
There are formal compounds and hemiformal compounds represented by ROCH ₂ OR and HOCH ₂ OR. Here R
is a C ₁ to C ₈ straight chain or branched alkyl group. Specifically, methylal, diethoxymethane,
Examples include di-iso-propoxymethane, di-n-butoxymethane, butoxyhydroxymethane, and the like. The second group of acetal compounds are:
There is a polyacetal compound represented by RO(CH ₂ O) _o R. Here, R is a _C1 - _C8 straight chain or branched alkyl group, and n is an integer of 2-20. Specifically, dioxymethylene dimethoxide,
Examples include tetraoxymethylene dioctoxide, decaoxymethylene diisopropoxide, dioxymethylene diethoxide, and the like. 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 using methods such as nuclear magnetic resonance spectroscopy (NMR), gas chromatography (GC), and liquid chromatography (LC). The third group of acetal compounds is

There is an acetal compound represented by the formula: Here, R is a C ₁ to C ₈ linear or branched alkyl group. Specific examples include dimethyl acetal, diethyl acetal, di-iso-propyl acetal, di-t-butyl acetal, dihexyl acetal, and dioctyl acetal. The orthoformic acid ester is a compound represented by HC(OR) ₃ , where R is a group selected from a C ₁ to _{C 4} linear alkyl group and a phenyl group. Specifically, methyl orthoformate, ethyl orthoformate,
Examples include diethylpropyl orthoformate, propyl orthoformate, and phenyl orthoformate. Alcohol is a compound represented by ROH, and R is a group selected from _C1 to _C20 linear or branched alkyl groups and aryl groups. Specifically, there are aliphatic alcohols such as methanol, ethanol, n-propanol, iso-butanol, lauryl alcohol and stearyl alcohol, and aromatic alcohols such as benzyl alcohol and 2-phenylethanol. Carboxylic acid is a compound represented by RCOOH, where R is a group selected from hydrogen, a C ₁ to _{C 20} linear or branched alkyl group, and an aryl group. Specifically, there are aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, lauric acid, and stearic acid, and aromatic carboxylic acids such as benzoic acid and iso-phthalic acid. Carboxylic acid anhydride is

【formula】

【formula】

【formula】

It is a compound represented by the formula: Here, R ₁ is a C ₁ to C ₂₀ linear alkyl group, R ₂ is hydrogen or a C ₁ to C ₂₀ linear alkyl group, and R ₃ is hydrogen or a C ₁ to _{C 3} linear or branched group. It is an alkyl group with a shape. Specifically, aliphatic carboxylic anhydrides such as acetic anhydride, propionic anhydride, stearic anhydride, succinic anhydride, dodecenylsuccinic anhydride, and maleic anhydride; aromatic carboxylic anhydrides such as phthalic anhydride and 4-methylphthalic anhydride; There are acid anhydrides. Among these molecular weight regulators, from the viewpoint of thermal stability and base stability of the polymer, formal compounds represented by ROCH ₂ OR, polyacetal compounds represented by RO(CH ₂ O) _o R, 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 reaction between polyoxymethylene and polyalkylene oxide is carried out without a solvent or in an organic medium. The reaction without a solvent is usually carried out by adding a Lewis acid to a mixture of polyoxymethylene and polyalkylene oxide in the form of solid powder or molten polyoxymethylene raw material. In addition, in the reaction in an organic medium, the organic medium containing the raw materials polyoxymethylene and polyalkylene oxide is usually
This is done by adding a Lewis acid. 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 aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene, ethyl ether , dioxane and other ether compounds. These organic media may be used alone or in combination of two or more. When using a molecular weight regulator, the molecular weight regulator is uniformly dissolved or dispersed in the reaction system. The concentration of the molecular weight regulator in the system is
Depending on the requirements, the desired molecular weight of the stabilized polyoxymethylene can be readily determined experimentally. The polyalkylene oxide is used in an amount of 0.01 to 100 parts by weight, more preferably 0.1 to 50 parts by weight, based on 100 parts by weight of raw material polyoxymethylene. Lewis acid, in the case of no solvent, 0.0005 to 0.1 part by weight per 100 parts by weight of raw material polyoxymethylene,
When using an organic medium, 1×10 ^-7 to 1×10 ^-1
Used in concentrations of mol/- organic medium. The reaction temperature is usually set between -20 and 230°C, but preferably between 20 and 210°C in the case of no solvent, and more preferably between 0 and 120°C when using an organic medium. . There is no particular limit to the reaction time, but from 5 seconds
Set between 300 minutes. In the case of no solvent, a basic substance such as sodium hydroxide, ammonia, amine, or quaternary ammonium salt is added to the system after a predetermined period of time has passed, and the reaction is completed. Stabilized polyoxymethylene can be put into practical use as it is by adding stabilizers, etc., or stabilized polyoxymethylene can be heated with water, alcohol, etc. and then stabilizers etc. are added to put it into practical use. You can also donate. When an organic medium is used, the polymer is separated from the organic medium after a predetermined period of time, and a basic substance such as sodium hydroxide, ammonia, amine, or quaternary ammonium salt is added to complete the reaction. It is also possible to add a stabilizer to the stabilized polyoxymethylene as it is for practical use. Alternatively, after heating the stabilized polyoxymethylene with water, alcohol, etc., a stabilizer etc. can be added for practical use. By using the method of the present invention which has been described in detail above, it has become possible to obtain a good stabilized polyoxymethylene. The features of the present invention are listed below. It is possible to produce stabilized polyoxymethylene with excellent thermal stability and base stability. Almost no decrease in molecular weight occurs during the stabilization reaction. The molecular weight of stabilized polyoxymethylene can be controlled arbitrarily by using a molecular weight regulator. By using a specific molecular weight regulator, it is possible to control the molecular weight and simultaneously improve thermal stability and base stability. Measured values in the following examples are based on the following measurement method. Molecular weight (number average molecular weight): Based on terminal group determination method.
That is, the terminal methoxy group (-OCH ₃ ) was quantified using the modified Zeisel method. Terminal hydroxyl group (-OH)
convert this group to an acetyl group (-
OCOCH ₃ ) and then quantified using infrared absorption spectroscopy. The terminal carboxyl group (-OCOR, R: hydrogen, alkyl group) was also quantified using infrared absorption spectroscopy. Reduced viscosity: 0.5gr./in p-chlorophenol-tetrachlorethylene (1:1 weight ratio) solution
Polymer concentration of dl, measured at 60℃. Base stability yield: at 5% polymer concentration in benzyl alcohol containing 1% tributylamine
Polymer recovery rate when heat treated at 150℃ for 60 minutes. It is a measure of base stability. Rv222: The amount of polymer remaining after heating at 222°C under vacuum for 50 minutes. It is a measure of thermal stability. The present invention will be explained below with reference to some examples.
The present invention is not limited to these examples. Example 1 Polyoxymethylene dimethoxide sufficiently dried under reduced pressure with a molecular weight of 60,500 and a reduced viscosity of 2.95.
50 gr., 10 gr. of polyethylene glycol (average molecular weight 5000) thoroughly dried under reduced pressure, 0.015 gr. of methylal, and 500 ml of substantially anhydrous toluene distilled over metallic sodium were added to the mixer, thermometer, and catalyst. A flask with a neck was charged and the contents were heated to 55°C. Next, a solution of 5 x 10 ^-4 mol of boron trifluoride dibutyl etherate dissolved in 5 ml of toluene was added through the catalyst inlet to initiate the reaction. After maintaining the contents of the flask at 55° C. for 45 minutes, the reaction was stopped by adding 1 ml of tributylamine. After separating the polymer, it was washed 5 times with methanol and vacuum dried at 60°C for 5 hours.
Got 49gr. This polymer had a desired molecular weight, with a molecular weight of 32,800 and a reduced viscosity of 1.68.
Furthermore, the base stabilization yield of this polymer was 97%, and the Rv222 of the polymer after base stabilization was 98.6%, indicating that it had good thermal stability and base stability. Example 2 A flask was charged with 200 gr. of polyoxymethylene diacetate having a molecular weight of 65800 and a reduced viscosity of 3.31, 25 gr. of polypropylene glycol diacetate (average molecular weight 3900), and 1000 ml of cyclohexane. The reaction was started by adding 1×10 ^-3 mol of triethyloxonium tetrafluoroborate, which was synthesized by reacting boron trifluoride diethyl etherate and epichlorohydrin in tetrahydrofuran. After maintaining the contents of the flask at 50 °C for 40 min,
The reaction was stopped by adding 10 ml of 1N NaOH aqueous solution.
Separately, washing and drying were performed to obtain 192 gr. of polymer.
The molecular weight of this polymer is 64600, the reduced viscosity is 3.28,
The base stabilization yield was 92%, and the yield of the base stabilized polymer was 92%.
The Rv was 97.0%, there was no decrease in molecular weight during the reaction, and a stabilized polyoxymethylene with good properties was obtained. Examples 3 to 10 Among the reagents used in Example 2, all of the reagents were Example 2
The results were shown in Table 1. In all Examples, stabilized polyoxymethylene having the desired molecular weight and excellent thermal stability and base stability was obtained. Comparative Example 1 All of the reagents used in Example 2 were used, except that 30 gr. of 1,3-dioxolane was used instead of polypropylene glycol diacetate, and 0.07 gr. of methylal was used as a molecular weight regulator. The same procedure was carried out, and the results obtained are also shown in Table 1. After the reaction, the molecular weight and viscosity of the polymer decreased significantly, and the base stabilization yield was also poor. Comparative Example 2 All operations were performed in the same manner as in Example 2, except that among the reagents used in Example 2, 40 gr. of ethylene glycol was used instead of polypropylene glycol diacetate, and 0.07 gr. of methylal was used as a molecular weight regulator. The obtained results are also shown in Table 1. During the reaction, the molecular weight of the polymer decreased significantly and only a low viscosity polymer was recovered. Example 11 350 gr. of end-capped polyoxymethylene (58% of the ends are capped with acetyl groups and 42% with methoxy groups) and 150 gr. of polytetraethylene glycol (average molecular weight 4950) with a molecular weight of 45,200 and a reduced viscosity of 2.23 were sufficiently uniformly mixed. After mixing, the mixture was poured into a flask. Next, the contents of the flask were stirred at high speed, and after raising the temperature to 90°C, a solution of 0.004 gr. of titanium tetrachloride dissolved in 5 ml of benzene was added to start the reaction. 20% after 10 minutes from the start of the reaction
The reaction was stopped by adding 10 ml of dioctylamine aqueous solution. Wash the polymer with methanol and dry it to form a polymer.
320gr. was recovered. The molecular weight of this polymer is
39,700, and the reduced viscosity was 2.03, and the decrease in molecular weight was extremely small. To 100 parts of this polymer, 0.5 part of cyanoguanidine, 2,2-methylene-bis(4
When 0.25 parts of methyl-6-tert-butylphenol was added to the mixture and subjected to molding, a molded product with strong physical properties was obtained. Example 12 After uniformly mixing 500 gr. of polyoxymethylene diacetate with a molecular weight of 53300 and a reduced viscosity of 2.69 and 18 gr. of polyethylene glycol (average molecular weight 20000), the mixture was mixed using a 30 mmφ extruder with L/D = 35 equipped with a vent port. Extruded. The time required for extrusion was 10 minutes, and the temperature of the molten resin at the die exit was 195°C. Over the 10 minutes required for extrusion, boron trifluoride diethyl etherate was added at a concentration of 2.0×10 ^-4 mol/
Toluene containing a concentration of was forcibly added from the vent port at a rate of 18 ml per minute. The average residence time of the resin from the vent port to the die exit was 28 seconds. The molten resin coming out of the die was introduced into water, and a total of 498 gr. of polymer was recovered as strands.
This polymer had a molecular weight of 49,800 and a reduced viscosity of 2.48.

【table】

Claims (1)

[Scope of Claims] 1. Polyoxymethylene having a number average molecular weight of 10,000 or more and the general formula [Formula] (R is hydrogen, an alkyl group, a substituted alkyl group, an aryl group,
They are selected from substituted aryl groups and may be the same or different. m=2~6, n=3~
A method for producing stabilized polyoxymethylene, which comprises reacting a polyalkylene oxide having a structure represented by (20000) in the presence of a Lewis acid. 2 The number average molecular weight of polyoxymethylene is
Claim 1 between 30,000 and 500,000
Manufacturing method described in section. 3. The production method according to claim 1, wherein the polyalkylene oxide is polyethylene oxide, a polyethylene oxide derivative, polypropylene oxide, or a polypropylene oxide derivative. 4 Average degree of polymerization of polyalkylene oxide (n)
is between 10 and 10,000. 5. The production method according to claim 1, in which a molecular weight regulator is present during the 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,
6. The method according to claim 5, wherein the compound is a compound selected from acetal compounds represented by the following formula: (n=2 to 20) and (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 reaction is carried out without a solvent. 9. The process according to claim 1, wherein the reaction is carried out in an organic medium.