TW201434886A - Production method for polyacetal copolymer - Google Patents

Abstract

Provided is a production method for a polyacetal copolymer that makes deactivation of a catalyst simple and efficient and that achieves a high polymerization yield and high quality using equipment that does not require a cleaning step and a process that involves a simple operation technique. The production method for a polyacetal copolymer uses trioxane as a main monomer (a) and a cyclic ether and/or a cyclic formal having at least one carbon-carbon bond as a comonomer (b). In the production method, a predetermined heteropolyacid is used as a polymerization catalyst (c) to perform copolymerization, an alkali metal, a hydroxide of an alkali earth metal, or an alkoxide compound (d) is added to the reaction product, melt kneading processing is performed, and the polymerization catalyst (c) is deactivated. It is preferable that the heteropolyacid be selected from among phosphomolybdic acid, phosphotungstic acid, and the like. It is preferable that the component (d) be an alkali metal hydroxide, and further preferable that the component (d) be lithium hydroxide or sodium hydroxide.

Description

Method for producing polyacetal copolymer

The present invention relates to a process for producing a polyacetal copolymer.

Conventionally, as a method for producing a polyacetal copolymer, three are known. The alkane is a main monomer, and a cyclic ether having at least one carbon-carbon bond and/or a cyclic methylal is copolymerized as a cation of a comonomer. As a cationic active catalyst used in such copolymerization, there have been proposals: Lewis acids, particularly halides of boron, tin, titanium, phosphorus, arsenic and antimony, such as boron trifluoride, tin tetrachloride, tetrachloride a compound such as titanium, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride and antimony pentafluoride, and a compound or salt thereof; protic acid such as perchloric acid; ester of protonic acid, especially perchloric acid An ester of an acid with a lower aliphatic alcohol, such as a butyl butyl perchlorate; an anhydride of a protic acid, particularly a mixed anhydride of a perchloric acid with a lower aliphatic carboxylic acid, such as an ethyl chloroperchlorate, or a Methyl oxonium hexafluorophosphate, triphenylmethyl hexafluoroarsenate, acetaminotetrafluoroborate, acetyl hexafluorophosphate and acetyl hexafluoroarsenate. Among them, boron trifluoride, or boron trifluoride and organic compounds, such as complex compounds with ethers, are most commonly used as A polymerization catalyst having an alkane as a main monomer is widely used in the industry.

However, a polymerization catalyst which is generally used, such as a boron trifluoride-based compound, requires a large amount (for example, 40 ppm or more based on all monomers) of a catalyst for polymerization. Therefore, the catalyst deactivation treatment after polymerization is difficult to fully perform, and There is a problem that the catalyst derived from the catalyst remains in the copolymer even if it is deactivated, and decomposition of the copolymer is promoted. Further, in general, the deactivation step of the catalyst is carried out in a large amount of an aqueous solution containing a basic compound such as triethylamine, and it is necessary to separate and dry the copolymer and the treatment liquid after the catalyst is deactivated, and to recover The troublesome steps of dissolving unreacted monomers and the like in the treatment liquid are problematic in terms of economy.

In order to simplify the cumbersome process of deactivation of such a catalyst, a method of adding a trivalent phosphorus compound to the produced copolymer (for example, refer to Patent Document 1 or the like) or a method of adding a hindered amine compound has been proposed (refer to Patent Document 2, etc.), but the effect as expected was not obtained.

On the other hand, a method for producing a polyacetal copolymer using a heteropoly acid as a catalyst has been proposed (for example, see Patent Document 3). Further, a method for producing a polyacetal copolymer which is prepared by copolymerizing a heteropoly acid as a catalyst to prepare a crude polyacetal copolymer, and optionally adding an amine group or a substituted amine to the reaction product is proposed. Base three The solid basic compound of at least one of the compound of the ring and the polyamine is subjected to melt-kneading treatment to deactivate the catalyst (for example, see Patent Document 4). According to this method, since the heteropoly acid is highly active, polymerization can be carried out with a very small amount of catalyst, and a high quality polyacetal copolymer can be provided. Further, since the activation of the catalyst is not performed by the melt kneading process without using the solution substantially, the troublesome steps are not required, and the economy is also excellent.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 55-42085

[Patent Document 2] Japanese Laid-Open Patent Publication No. 62-257922

[Patent Document 3] Japanese Patent Laid-Open No. 1-170610

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2003-026746

In recent years, a high-quality polyacetal copolymer having particularly excellent stability and a small amount of formaldehyde is sought, but in the methods described in Patent Documents 1 to 4, such a demand is severe. In order to meet such a demand, it is sought to further deactivate the catalyst more efficiently, and to further decompose the unstable terminal portion of the crude polyacetal copolymer after deactivation of the catalyst to stabilize it. improve.

It is an object of the present invention to provide a method for producing a stabilized polyacetal copolymer which can be selected simply by selecting a catalyst, a catalyst deactivator, an unstable terminal treatment agent or a combination of these. Efficiently deactivate the catalyst, so that the equipment without the washing step and the simple processing in terms of operation technology, the production of high polymerization yield, the endless portion of the unstable portion, the stability of the heat, and the amount of formaldehyde released Very little stabilized polyacetal copolymer.

In order to achieve the above-mentioned problems, the inventors of the present invention have conducted research on the types of catalysts and the catalyst deactivation method and the unstable terminal treatment method corresponding thereto, and as a result, found that the heteropoly acid represented by the following general formula (1) is used as a catalyst. And for the catalyst deactivation and unstable terminal treatment, the alkali metal or alkaline earth metal hydroxide or alkoxide compound is used for melt-kneading treatment, and although the polymerization activity of the catalyst is high, it can be extremely small and And quickly inactivate and reduce the catalyst, The invention is completed by stabilizing the unstable end, and the equipment and operation technology are also easy, and the above object can be achieved. More specifically, the present invention provides the following matters.

(1) The present invention is a method for producing a polyacetal copolymer, which is based on When the alkane is used as a main monomer (a), a cyclic ether having at least one carbon-carbon bond, and/or a cyclic methylal as a comonomer (b) to produce a polyacetal copolymer, the following formula is used ( 1) The heteropoly acid is copolymerized as a polymerization catalyst (c), and an alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is added to the reaction product, and melt-kneading is performed to make The polymerization catalyst (c) is deactivated.

H _m [M ¹ _x ‧M ² _y O _Z ]‧nH ₂ O‧‧‧‧‧ (1) In the formula (1), M ¹ represents one or two elements selected from P and Si In the central element of the composition, M ² represents one or more kinds of coordination elements selected from the group consisting of W, Mo, and V. x represents an integer of 1 or more and 10 or less, and y represents an integer of 6 or more and 40 or less. z represents an integer of 10 or more and 100 or less. m represents an integer of 1 or more. n represents an integer of 0 or more and 50 or less. ]

(2) Further, the present invention is the process for producing a polyacetal copolymer according to (1), wherein the comonomer (b) is selected from the group consisting of 1,3-dioxolane , diethylene glycol methylal, 1,4-butanediol methylal, 1,3-two At least one of an alkane or an ethylene oxide.

(3) The method of producing a polyacetal copolymer according to (1) or (2), wherein the heteropoly acid is selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdic acid, At least one of phosphomolybdic vanadate, phosphomolybdenum tungstic acid, phosphotungstic acid, lanthanum tungstic acid, lanthanum molybdate, lanthanum molybdenum tungstic acid, or lanthanum molybdenum tungstic acid.

(4) Further, the present invention is the polyacetal copolymerization according to any one of (1) to (3) The method for producing a compound of the above-mentioned alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) represented by the following formula (2)

(XO) _n M ³ ‧‧‧‧‧ (2) In the formula (2), X represents hydrogen, an unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted alkyl group or a phenyl group. The unsubstituted alkyl group is linear, branched or cyclic. The substituent of the substituted alkyl group is a methyl group. M ³ represents an alkali metal element or an alkaline earth metal element. n is 1 or 2. ]

(5) The method for producing a polyacetal copolymer according to any one of (1) to (4), wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound ( d) is (i) at least one hydroxide selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide or barium hydroxide, or (ii) selected from lithium pentoxide At least one alkoxide compound of sodium methoxide, sodium ethoxide, sodium butoxide, sodium benzoate, potassium methoxide, potassium ethoxide, potassium butoxide, magnesium methoxide or calcium sulphate.

(6) The method for producing a polyacetal copolymer according to (5), wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is selected from lithium hydroxide At least one of hydroxides of sodium hydroxide and potassium hydroxide.

(7) The method for producing a polyacetal copolymer according to (6), wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is selected from lithium hydroxide Or at least one hydroxide in sodium hydroxide.

(8) The method for producing a polyacetal copolymer according to any one of (1) to (7), wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound ( d) the amount of addition, obtained by using a copolymerization reaction The crude polyacetal copolymer 1 kg is 0.001 to 0.25 milliequivalent.

(9) The method for producing a polyacetal copolymer according to any one of (1) to (8), wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) For the addition of the aforementioned reaction product, (i) the above-mentioned alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is in the form of a solution, and the crude polyacetal obtained by the copolymerization reaction is used in total. The polymer is directly added, or (ii) the solution of the alkali metal or alkaline earth metal hydroxide or the alkoxide compound (d) is contained in the powder of the polyacetal copolymer, and after being uniformly dispersed, it is dispersed. The latter powder is added to the aforementioned crude polyacetal copolymer, or (iii) the above-mentioned alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is directly and uniformly dispersed in a solid state in the polyacetal copolymerization. After the powder of the substance, the dispersed powder is added to the above-mentioned crude polyacetal copolymer to carry out, and the b value of the polyacetal copolymer pellet after deactivation of the polymerization catalyst (c) measured by a color difference meter is used. It is 2.0 or less.

According to the present invention, by using a hydroxide or an alkoxide compound of an alkali metal or an alkaline earth metal as a deactivator of a polymerization catalyst, not only the polymerization catalyst can be effectively deactivated, but also the unstable terminal portion can be stabilized. It is possible to economically produce a high-quality polyacetal copolymer having excellent thermal stability and a small amount of formaldehyde generated by a simple manufacturing process.

Moreover, according to the present invention, by the dry method compared to the conventional wet deactivation method, the polymerization step can be quickly and completely deactivated by simplifying the deactivation step and omitting the extremely rational steps of the washing step, and then The stability of the unstable end portion is performed. As a result, it is possible to prevent decomposition or deterioration of the catalyst from occurring. In other cases, it is possible to economically produce a polyacetal copolymer having excellent quality which is stable to heat and which is unstable and has a small amount of formaldehyde emission.

The present invention is not limited by the following embodiments, but may be appropriately modified and implemented within the scope of the present invention.

<Method for Producing Polyacetal Copolymer>

In the present invention, a cyclic terpolymer of formaldehyde is used. When alkane is used as a main monomer (a), a cyclic ether having at least one carbon-carbon bond, and/or a cyclic methylal as a comonomer (b) to produce a polyacetal copolymer, a specific heteropoly is used. The acid is copolymerized as a polymerization catalyst (c), and a specific salt (d) is added to the reaction product, and melt-kneading treatment is performed to deactivate the polymerization catalyst (c).

[Comonomer (b)]

As the comonomer, a compound (b) selected from a cyclic ether having at least one carbon-carbon bond and a cyclic methylal is used. Representative examples of the compound (b) used as a comonomer include 1,3-dioxolane, diethylene glycol methylal, 1,4-butanediol methylal, and 1,3-two. Alkane, ethylene oxide, propylene oxide, epichlorohydrin, and the like. Among them, considering the stability of the polymerization, it is preferably 1,3-dioxolane, diethylene glycol methylal, 1,4-butanediol methylal, 1,3-two Alkane, ethylene oxide, and the like. Further, a cyclic ester such as β-propiolactone or a vinyl compound such as styrene or the like can also be used. Further, as the comonomer, a monofunctional cyclic ether having a substituent unit such as butyl glycidyl ether or 2-ethylhexyl epoxidized ether or a cyclic methylal may be used. Further, as the comonomer, a compound having two polymerizable cyclic ether groups or cyclic methylal groups such as diglycidyl ether or dimethyl acetal of an alkylene glycol can also be used, for example. Butanediol dimethylene glyceryl ether, butanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, etc. One or more compounds of a polymerizable cyclic ether group or a cyclic methylal group. The polyacetal copolymer which thereby forms a branched structure or a crosslinked structure is also an object of the present invention.

In the present invention, the amount of the compound (b) selected from the group consisting of a cyclic ether and a cyclic methylal used as a comonomer is the ratio of all the monomers (the total amount of the main monomer and the comonomer). In other words, it is 0.1 to 20 mol%, preferably 0.2 to 10 mol%. When the amount is less than 0.1 mol%, the unstable terminal portion of the crude polyacetal copolymer formed by the polymerization increases, and the stability is deteriorated. If the amount of the comonomer is too large, the resulting copolymer becomes soft. , the melting point drops, not ideal.

[Polymerization Catalyst (c)]

One of the features of the present invention is that a heteropolyacid is used as the polymerization catalyst (c) in the production of the polyacetal copolymer as described above.

In the present invention, the heteropoly acid used as the polymerization catalyst (c) is a general term for a polylactic acid produced by dehydration condensation of a different oxoacid, and has a specific hetero element in the center and has a condensed acid atom. A mononuclear or complexed counterion formed by condensation of an acid group. Such a heteronuclear condensed acid can be represented by the following general formula (1).

H _m [M ¹ _x ‧M ² _y O _Z ]‧nH ₂ O‧‧‧‧‧‧(1)

In the formula (1), M ¹ represents a central element composed of one or two elements selected from the group consisting of P and Si, and M ² represents one or more kinds of coordination elements selected from the group consisting of W, Mo and V. x represents an integer of 1 or more and 10 or less, and y represents an integer of 6 or more and 40 or less. z represents an integer of 10 or more and 100 or less. m represents an integer of 1 or more. n represents an integer of 0 or more and 50 or less.

Specific examples of the heteropoly acid include phosphomolybdic acid, phosphotungstic acid, phosphomolybdic acid, phosphomolybdic acid, phosphomolybdenum tungstic acid, phosphotungstic acid, lanthanum tungstic acid, lanthanum molybdate, and lanthanum molybdenum. Tungstic acid, lanthanum molybdenum tungstic acid, and the like Among them, in consideration of the stability of the polymerization and the stability of the heteropoly acid itself, the heteropoly acid is preferably any one of hydrazine molybdate, decanoic acid, phosphomolybdic acid or phosphotungstic acid.

In the present invention, the amount of the above heteropoly acid used may vary depending on the type thereof, and the polymerization reaction may be appropriately changed, but in general, it is 0.05 to 100 ppm (hereinafter less) with respect to the total amount of the monomers to be polymerized. The range described as weight/weight ppm) is preferably 0.1 to 50 ppm. Further, if a heteropoly acid having a very strong action such as phosphomolybdic acid or phosphotungstic acid is used, it is sufficient to use an amount of 0.1 to 10 ppm. Such a phenomenon that copolymerization can be carried out with a small amount of a catalyst, there are only a few unsatisfactory reactions which can cause decomposition of the main chain of the polymer due to the catalyst, and depolymerization, and the like, for suppressing unstable formate. The terminal group (-O-CH=O), the hemiacetal terminal group (-O-CH ₂ -OH), and the like are produced efficiently, and are also advantageous in terms of economy.

In order to allow the reaction to proceed uniformly, it is preferred to use the polymerization catalyst after dilution with a passive solvent which does not adversely affect the polymerization, and to add it to the main monomer and/or comonomer. Examples of the blunt solvent include low molecular weight carboxylic acids having a carbon number of 1 to 10 such as formic acid, acetic acid, propionic acid, and butyric acid, and methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. Carbon number 1 to 10 such as 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 3-methyl-1-butanol, and 1-hexanol An ester obtained by condensation of a low molecular weight alcohol; acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, methyl tert-butanone, etc. Low molecular weight ketones with carbon number 1~10 It is an ideal example, but it is not limited to this. In view of ease of industrial availability, etc., methyl formate, ethyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, 2-butanone, methyl isobutyl ketone or the like is most preferred. The polymerization catalyst is preferably dissolved in the above-mentioned passive solvent at a concentration of 1 to 30% by weight, but is not limited thereto. Further, a method in which the amount of the polymerization catalyst is mixed with a part or the total amount of one or more of the main monomer, the comonomer, and the molecular weight modifier is added, and the solution is added to the polymerization system to carry out polymerization. Ideal.

[Preparation of copolymer]

In the present invention, when preparing a crude polyacetal copolymer by polymerization, it is possible to use three conventionally known The copolymerization of the alkane is carried out by the same equipment and method. That is, it may be a batch type, a continuous type, or a semi-continuous type, and generally, a method of obtaining a solid powdery block polymer by performing polymerization while using a liquid monomer. As the polymerization apparatus used in the present invention, in the batch type, a commonly used reaction tank equipped with a stirrer can be used, and in the continuous type, a co-kneader, a twin-screw type continuous extrusion mixer can be used, Two-axis paddle type continuous mixer, in addition, three of the proposals so far can be used In the continuous polymerization apparatus such as an alkane, two or more types of polymerization apparatuses may be used in combination.

The polymerization method is not particularly limited, and if it is previously proposed, it will be three The alkane, the comonomer, and the heteropoly acid as a catalyst are kept in a liquid state in advance, and are sufficiently mixed, and the obtained reaction raw material mixture is supplied to the polymerization device for copolymerization reaction, thereby reducing the amount of the catalyst required. It is advantageous for obtaining a polyacetal copolymer having a smaller amount of formaldehyde emission. For a more preferable polymerization method, the polymerization temperature is carried out at a temperature ranging from 60 to 120 °C.

In the present invention, the above-mentioned main monomer (a) and comonomer (b) are polymerized. In the preparation of the polyacetal copolymer, a known chain transfer agent such as a low molecular weight linear acetal such as methylal may be added in order to adjust the degree of polymerization.

Further, the polymerization reaction is desirably carried out in a state in which impurities having active hydrogen are not substantially contained, such as water, methanol, formic acid, etc., for example, in a state of 10 ppm or less, for which it is desirable to use as much as possible. Three impurity components The alkane, cyclic ether and/or cyclic methylal are used as the main monomer or comonomer.

[Hydroxide or alkoxide compound (d) of an alkali metal or alkaline earth metal]

The present invention is characterized in that, if obtained by copolymerization in the above manner, a polyacetal copolymer (crude polyacetal copolymer) containing a polymerization catalyst and having a terminal portion having an unstable portion is added with an alkali metal or an alkaline earth. The metal hydroxide or the alkoxide compound (d) is melt-kneaded to inactivate the polymerization catalyst, and at the same time, stabilizes the unstable terminal group possessed by the polyacetal copolymer (crude copolymer). Hereinafter, the "alkali metal or alkaline earth metal hydroxide or alkoxide compound" is also referred to as component (d). In the stabilization treatment, the crude polyacetal copolymer obtained by the copolymerization reaction can be directly and easily added without washing, and the component (d) can be directly added.

The component (d) is preferably a compound represented by the following formula (2).

(XO) _n M ³ ‧‧‧‧‧‧(2)

In the formula (2), X represents hydrogen, an unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted alkyl group or a phenyl group. The unsubstituted alkyl group is linear, branched or cyclic. The substituent of the substituted alkyl group is a methyl group. M ³ represents an alkali metal element or an alkaline earth metal element. n is 1 or 2.

The component (d) is preferably lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, lithium pentoxide, sodium methoxide, sodium ethoxide, sodium butoxide, and benzene. Sodium, potassium methoxide, potassium ethoxide, potassium third potassium hydride, magnesium methoxide or calcium sulphate is most preferred, but is not limited thereto.

Further, in consideration of the hue of the polyacetal copolymer after deactivating the polymerization catalyst (c), the component (d) is particularly preferably an alkali metal hydroxide, more preferably lithium hydroxide or sodium hydroxide.

In the present invention, the salt (d) represented by the above formula (2) may be used singly or in combination of two or more.

The content of the component (d) is not particularly limited, and it is preferable to (i) the amount of the catalyst remaining in the polymer, (ii) the type or amount of the unstable terminal group generated depending on various conditions of polymerization, and (iii) (d) The degree of activity of the component or the processing conditions (temperature, time, contact speed, etc.) are appropriately changed. Specifically, the content of the component (d) is preferably extremely small, and is preferably 0.001 to 0.25 milliequivalents, more preferably 0.002 milliequivalent to 0.10 milliequivalent, relative to 1 kg of the crude polyacetal copolymer obtained by the copolymerization reaction. More preferably, it is 0.002 to 0.025 milliequivalent. The lower limit of the content of the component (d) affects the melt index (MI), and the content of the component (d) relative to 1 kg of the polyacetal copolymer is 0.001 milliequivalent or more, so that the MI can be about 10 or less by 0.002. A millimeter or more can make the MI value 10 or less. The upper limit of the content of the component (d) affects the hue (b value) of the pellet, and the polymerization catalyst (c) can be obtained by setting the content of the component (d) of 1 kg with respect to the crude polyacetal copolymer to 0.25 milliequivalent or less. The b value of the polyacetal copolymer after deactivation is 2.0 or less. In addition, the b value of the polyacetal copolymer after the polymerization catalyst (c) is deactivated is 1.0 or less with respect to the content of the component (d) of 1 kg of the crude polyacetal copolymer is 0.10 milliequivalent or less. . By relative to crude The content of the component (d) of 1 kg of the polyacetal copolymer is 0.10 milliequivalent or less, and the b value of the polyacetal copolymer after the polymerization catalyst (c) is deactivated becomes 0.0 or less.

When the amount of the component (d) is excessive, the hue of the polyacetal copolymer after the polymerization catalyst (c) is deactivated may be deteriorated. If the amount is too small, the efficiency of deactivation or the stability of the terminal portion may be unstable. The possibility that the reform cannot be fully achieved is not ideal.

[Inactivation of catalyst]

In the present invention, in order to increase the hue of the polyacetal copolymer after the polymerization catalyst (c) is deactivated, it is preferred that the content of the component (d) be extremely small, but a very small amount of the component (d) is extremely difficult to uniformly Dispersed in the whole. Therefore, the addition of the component (d) is preferably carried out by any of the following (i) to (iii).

(i) The component (d) is directly added to the crude polyacetal copolymer obtained by copolymerization in the form of a solution.

(ii) A solution containing the component (d) in the powder of the polyacetal copolymer is uniformly dispersed, and the dispersed powder is added to the crude polyacetal copolymer. or

(iii) After the component (d) is uniformly dispersed in the solid state to the powder of the polyacetal copolymer, the dispersed powder is added to the crude polyacetal copolymer.

When the component (d) is contained in the powder of the polyacetal copolymer, a general mixer such as a horizontal cylinder type, a V type, a belt type, a paddle type, or a high-speed flow type can be used. Further, the mixture may be directly subjected to a melting treatment, or may be subjected to a melting treatment by heating and distilling off the solvent under reduced pressure. Further, the deactivation and stabilizer solution may be supplied from the inlet and/or the middle of the extruder by spraying or the like. At this time, the deactivation and stabilizer solution can also be supplied in multiple stages.

By adding the component (d) as described above, a very small amount of (d) can be formed. The fraction was uniformly dispersed to the whole, and the results were measured using a color difference meter. The b value of the polyacetal copolymer which can deactivate the polymerization catalyst (c) is 2.0 or less. In the present invention, the b value is a colorimeter SE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), and a predetermined amount of pellets are placed in a colorimetric container (circular container) for pellet measurement. The sample table, the lid is closed, and the value displayed when measuring.

In particular, the component (d) is preferably a hydroxide of an alkali metal, and if it is appropriately added, the b value can be made 0.0 or less. Further, the component (d) is more preferably lithium hydroxide or sodium hydroxide, and if the amount is appropriately added, the b value can be -0.1 or less.

In the present invention, when the catalyst is deactivated after polymerization, the unreacted monomer is preferably less preferred, and the unreacted monomer (representing the total of the main monomer and the comonomer) is 10 in the crude copolymer. The weight% or less is more preferably 5% by weight or less, and particularly preferably 3% by weight or less. Thereby, it is possible to achieve a particularly desirable aspect of the present invention in which the crude polyacetal copolymer produced by the polymerization is treated without washing. In order to reduce unreacted monomers, generally, as long as the polymerization rate is increased to a certain level or more, in the case of the present invention, it is easy to adjust the amount of the catalyst to be used and the polymerization time (the residence time in the continuous mode). By using a highly active heteropolyacid catalyst, even a small amount of catalyst can be achieved in a shorter period of time. Further, after the copolymerization reaction, a part of the residual monomer may be evaporated and vaporized to be removed, so that a predetermined residual monomer amount is obtained. Further, after copolymerization or after copolymerization, or unreacted three recovered as a gas The alkane and comonomer are liquefied and reused directly as part of the starting monomer, which is more economical.

Further, if necessary, a conventionally known catalyst deactivator or a decomposing agent having an unstable terminal may be used in combination with the above component (d).

In the present invention, as a function of the deactivating agent and the stabilization treatment agent (d) The addition of the components may be carried out at any stage before or after the melting of the crude polyacetal copolymer, or may be carried out in both stages. Further, the method of adding the component (d) can be supplied in multiple stages and in multiple stages.

Further, when the component (d) is added as the deactivation and stabilization treatment agent, the crude copolymer is preferably a fine powder or granule. For this reason, the reactor preferably has a function of sufficiently pulverizing the bulk polymer, but it is also possible. The polymerized reactant was additionally pulverized using a pulverizer. In the deactivation treatment, the particle size of the crude copolymer is at least 90% by weight, preferably 10 mm or less, preferably 4 mm or less, more preferably 2 mm or less.

The melt kneading treatment apparatus is not particularly limited, and examples thereof include a function of kneading a molten copolymer and preferably having an exhaust function, for example, uniaxial or multiaxial continuous extrusion having at least one vent hole. A kneading machine, a cokneader, etc. In the present invention, in the melt kneading treatment, complete deactivation of the polymerization catalyst and reduction in stability of the unstable terminal portion are performed. The melt kneading treatment is preferably a temperature range of up to 260 ° C above the melting point of the copolymer, and if it is higher than 260 ° C, decomposition degradation of the polymer occurs, which is not preferable.

In the present invention, the above melt-kneading treatment is preferably carried out in the presence of an antioxidant. As the antioxidant, a conventionally known stabilizer for a polyacetal resin can be used. For example, various hindered phenol-based antioxidants can be used. For example: 2,6-di-t-butyl-4-methylphenol, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate ], 1,6-hexanediol-bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 肆[3-(3,5-di- Tributyl-4-hydroxyphenyl)propionate]methane, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxyhydrolaurylamine), 2- Tributyl-6-(3'-tert-butyl-5'-methyl-2'-hydroxybenzyl)-4-tolyl acrylate, 3,9-bis[2-{(3-third Butyl-4-hydroxy-5-tolyl)propanoid Oxygen}-1,1'-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane and the like. Further, these hindered phenol-based antioxidants may be partially or completely added to the main monomer or comonomer before polymerization, and then the hindered phenol-based antioxidants are not particularly excessively added, that is, they are not touched by polymerization. The activity of the medium causes a poor effect and is an ideal implementation.

Further, at this stage, a stabilizer which is various kinds of polyacetal resins may be added as needed. Further, for example, an inorganic filler such as glass fiber, a crystallization accelerator (nucleating agent), a releasing agent, an antioxidant, or the like may be added.

As described above, when the component (d) is added as a deactivation and stabilization treatment agent to the crude copolymer, and the melt-kneading treatment is performed, the formaldehyde gas, the unreacted monomer, the oligomer, and the deactivated product are usually decomposed. The stabilizer and the like are removed from the exhaust portion of the extruder under reduced pressure, and formed into pellets to prepare a resin processing product. The pellets may need to be dried. In the case of drying, for example, drying at 135 ° C for about 4 hours.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[Table 1]

<Examples 1 to 27>

[The main monomer (a) three Copolymerization of alkane with a cyclic ether of a comonomer (b) and/or a cyclic methylal]

The polymerization apparatus uses a continuous biaxial polymerization machine. In the above-mentioned polymerization machine, a jacket for passing a medium for heating or cooling is provided, and two rotating shafts in which a plurality of blades for stirring and propulsion are attached are provided inside the longitudinal direction. For the jacket of the biaxial polymerization machine, the warm water of 80 ° C was passed, and the two rotating shafts were rotated at a constant speed, and the continuous feeding of 1000 ppm of methylal as a chain transfer agent was continuously fed at one end thereof. Monomer (a) of three a mixture of 96.2% by weight of alkane and 3.8% by weight of comonomer (b) shown in Table 1, and at the same time, 0.3% by weight of the heteropolyacid shown in Table 1 as the polymerization catalyst (c) The % methyl formate solution was continuously added and copolymerized in an amount shown in Table 1 with respect to all the monomers. In Table 1, the amount of the polymerization catalyst added is a weight ratio (unit: ppm) based on the total of all the monomers, and a molar equivalent of 1 kg of the crude polyacetal copolymer obtained by the copolymerization reaction (unit: equivalent).

[Inactivation of Polymerization Catalyst (c)]

The reaction product obtained by the copolymerization (crude polyacetal copolymer) was discharged from the discharge port provided at the other end of the polymerization machine, and at the same time, the salt (d) shown in Table 1 was added for the catalyst deactivation. The addition of the salt (d) was carried out in the following manner. When the column of "addition method" in Table 1 is "solid", the component (d) is uniformly dispersed in a solid state and dispersed in the powder of the polyacetal copolymer, and the dispersed powder is added to the above reaction product. When the column of "addition method" in Table 1 is "aqueous solution", a 10 wt% aqueous solution containing the component (d) is prepared so as to have a predetermined molar number, and 10 mL of this aqueous solution is added to the powder of the polyacetal copolymer, and Add to the above reaction product. When the column of "addition method" in Table 1 is "methanol solution", a 10 to 30 wt% methanol solution containing the component (d) is prepared so as to have a predetermined molar number, and 10 mL of this aqueous solution is added to the polyacetal copolymer. In the powder, and added to the above reaction product.

Next, 0.3 wt% of triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] was added as an antioxidant, and a double with an exhaust port was used. The shaft extrusion machine was melt-kneaded and extruded under the conditions of a temperature of 220 ° C and a vacuum of 5 mmHg in the exhaust portion to prepare pellets of the polyacetal copolymer of Examples 1 to 16. grain.

<Comparative Examples 1 to 4>

The polyacetal copolymer of Comparative Examples 1 and 2 was prepared in the same manner as in Example 1 except that the compound shown in Table 1 (melamine or melamine resin) in the amounts shown in Table 1 was added as the deactivating agent. Pellet. Further, pellets of the comparative examples 3 and 4 polyacetal copolymer were prepared in the same manner as in the examples except that boron trifluoride was used as a polymerization catalyst and the amounts described in Table 1 were used.

<evaluation>

The pellets of the polyacetal copolymer of the examples and the comparative examples were dried at 135 ° C for 4 hours, and then a melt index (MI), an alkali decomposition ratio, a formaldehyde emission amount, and a polymerization catalyst were measured ( c) The hue of the polyacetal copolymer after deactivation.

[Evaluation of Melt Index (MI)]

A melt index measuring device: Melt Indexer L202 type (manufactured by Takara thermistor Co., Ltd.) was used, and the value measured at a load of 2.16 kg and a temperature of 190 ° C for 7 minutes was defined as a melt index (g/10 min). The results are shown in Table 2. In the present embodiment, the melt index (MI) is defined as a characteristic value corresponding to the molecular weight. That is, the lower the MI, the higher the molecular weight is judged, and the higher the MI, the lower the molecular weight is judged.

[Evaluation of alkali decomposition rate (the amount of unstable portion)]

The copolymerized pellets in the examples and the comparative examples were pulverized, and about 1 g of the concentrate was placed in a closable container together with 100 mL of a 50% aqueous methanol solution containing 0.5% by weight of ammonium hydroxide, and sealed at 180 ° C. After heating for 45 minutes, the amount of formaldehyde dissolved in the liquid was quantitatively analyzed. The results are shown in Table 2. The alkali decomposition rate is represented by a ratio (unit: %) to 100% by weight of the copolymer pellet.

[Evaluation of formaldehyde emission]

The samples of the examples and the comparative examples were filled in a cylinder held at 200 ° C, and after melting for 5 minutes, the melt was extruded from the cylinder into the sealed container. Nitrogen gas was flowed into the sealed container, and the formaldehyde contained in the outflowing nitrogen gas was dissolved in water to be captured, and the concentration of formaldehyde in the water was measured to determine the weight of formaldehyde released from the molten material. The weight of the formaldehyde was divided by the weight of the melt as the amount of formaldehyde released (in ppm). The results are shown in Table 2.

[Evaluation of Hue of Pellets]

Using a color difference meter SE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), a predetermined amount of pellets was placed in a colorimetric container (round container) for pellet measurement, placed on a sample stage, and a lid was placed thereon, and the measurement was performed. Read the displayed b value. The results are shown in Table 2.

[Table 2]

It is confirmed that in the present invention, the polymerization catalyst is a heteropoly acid represented by the above formula (1), and the deactivating agent of the heteropoly acid is an alkali metal or alkaline earth metal hydroxide or alkoxide compound (d). Therefore, a high polymerization yield can be obtained in a very small amount, and, after the polymerization, it is only necessary to add the component (d) to the crude copolymer and perform melt-kneading, thereby simply providing a very high-quality polyacetal copolymer as a polymer. Products (Examples 1 to 26).

The lower limit of the content of the component (d) affects (MI). Confirmed: if (d) becomes The content of the fraction is 0.002 milliequivalent or less with respect to 1 kg of the crude polyacetal copolymer, and MI is 10 g/min or less, and the polymerization catalyst can be deactivated with good efficiency, and the unstable terminal can be sufficiently stabilized (Example 2~ 26).

On the other hand, the upper limit of the content of the component (d) affects the value of (b). It was confirmed that the content of the component (d) is 0.10 milliequivalent or less based on 1 kg of the crude polyacetal copolymer, and the b value is 1.0 or less, and the polyacetal copolymer after deactivating the polymerization catalyst (c) The hue is excellent (Examples 1 to 25). In addition, when the content of the component (d) is 0.025 milliequivalent or less based on 1 kg of the crude polyacetal copolymer, and the b value is 0.0 or less, the hue of the polyacetal copolymer after the polymerization catalyst (c) is deactivated More excellent (Examples 1 to 18).

On the other hand, it was confirmed that if the deactivating agent is melamine, melamine resin or CTU guanamine, the polymerization catalyst can be sufficiently deactivated, and a larger amount of deactivator is required than the embodiment. There are residual problems in economics (Comparative Examples 1 to 3). Further, the alkali decomposition rate and the amount of formaldehyde released did not satisfy the quality level required in recent years (Comparative Examples 1 to 3).

Claims (9)

A method for producing a polyacetal copolymer, in three When the alkane is used as a main monomer (a), a cyclic ether having at least one carbon-carbon bond, and/or a cyclic methylal as a comonomer (b) to produce a polyacetal copolymer, the following formula is used ( 1) The heteropoly acid is copolymerized as a polymerization catalyst (c), and an alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is added to the reaction product, and melt-kneading is performed to make The polymerization catalyst (c) is deactivated: H _m [M ¹ _x ‧M ² _y O _Z ]‧nH ₂ O‧‧‧‧‧ (1) In the formula (1), M ¹ represents a selected from P and Si A central element composed of one or two elements, M ² represents a complex element selected from one or more of W, Mo, and V; x represents an integer of 1 or more and 10 or less, and y represents an integer of 6 or more and 40 or less; z represents an integer of 10 or more and 100 or less; m represents an integer of 1 or more; and represents an integer of 0 or more and 50 or less. The method for producing a polyacetal copolymer according to claim 1, wherein the comonomer (b) is selected from the group consisting of 1,3-dioxolane and diethylene glycol. Methylal, 1,4-butanediol, acetal, 1,3-two At least one of an alkane or an ethylene oxide. The method for producing a polyacetal copolymer according to claim 1 or 2, wherein the heteropoly acid is selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdic acid, phosphomolybdic acid, and phosphorus molybdenum. At least one of tungsten vanadic acid, phosphotungstic acid, lanthanum tungstic acid, lanthanum molybdic acid, lanthanum molybdenum tungstic acid, or lanthanum molybdenum tungsten vanadate. The method for producing a polyacetal copolymer according to any one of claims 1 to 3, wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is as follows Formula (2) represents: (XO) _n M ³ ‧‧‧‧‧ (2) In the formula (2), X represents hydrogen, an unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted alkyl group or a phenyl group; The substituted alkyl group is linear, branched or cyclic; the substituent of the substituted alkyl group is a methyl group; M ³ represents an alkali metal element or an alkaline earth metal element; n is 1 or 2. The method for producing a polyacetal copolymer according to any one of claims 1 to 4, wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is: (i) At least one hydroxide selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide or barium hydroxide, or (ii) selected from the group consisting of lithium pentoxide, sodium methoxide, and At least one alkoxide compound of sodium oxide, sodium tributoxide, sodium benzoate, potassium methoxide, potassium ethoxide, potassium butoxide, magnesium methoxide or calcium oxide. The method for producing a polyacetal copolymer according to claim 5, wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is selected from the group consisting of lithium hydroxide and sodium hydroxide. At least one hydroxide of potassium hydroxide. The method for producing a polyacetal copolymer according to claim 6, wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is selected from lithium hydroxide or sodium hydroxide. At least one of the hydroxides. The method for producing a polyacetal copolymer according to any one of claims 1 to 7, wherein the amount of the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is relatively Obtained by using copolymerization The crude polyacetal copolymer 1 kg is 0.001 to 0.25 milliequivalent. The method for producing a polyacetal copolymer according to any one of claims 1 to 8, wherein the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) is for the aforementioned reaction product Adding, (i) directly adding the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) as a solution to the crude polyacetal copolymer obtained by the copolymerization reaction, Or (ii) the solution of the alkali metal or alkaline earth metal hydroxide or the alkoxide compound (d) is contained in a powder of the polyacetal copolymer, and after uniformly dispersing the powder, the dispersed powder is Adding a crude polyacetal copolymer, or (iii) directly or uniformly dispersing the alkali metal or alkaline earth metal hydroxide or alkoxide compound (d) in a solid state in a powder of a polyacetal copolymer; The dispersed powder was added to the crude polyacetal copolymer to carry out; the polyacetal copolymer pellet after deactivation of the polymerization catalyst (c) measured by a color difference meter had a b value of 2.0 or less.