JP2014094999A - Method of manufacturing polyacetal copolymer - Google Patents

Abstract

In producing a polyacetal copolymer, the deactivation of a catalyst is simplified and efficient, and a high process yield and high quality are realized by a simple process as equipment and operation technique that does not require a washing step.
The present invention relates to a method for producing a polyacetal copolymer comprising trioxane as a main monomer (a) and a cyclic ether having at least one carbon-carbon bond and / or a cyclic formal as a comonomer (b). . In this method, a polymerization catalyst (c) is copolymerized using a predetermined heteropolyacid, a predetermined guanidine compound (d) is added to the reaction product, and melt-kneading treatment is carried out to obtain a polymerization catalyst (c). Deactivate. The heteropolyacid is preferably selected from phosphomolybdic acid, phosphotungstic acid and the like, and the guanidine compound is 1- (o-tolyl) biguanide, phenylbiguanide, 1,3-diphenylguanidine, 2-aminobenzimidazole. Etc. are preferably selected.
[Selection figure] None

Description

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

  Conventionally, as a method for producing a polyacetal copolymer, cationic copolymerization using trioxane as a main monomer and a cyclic ether having at least one carbon-carbon bond and / or a cyclic formal as a comonomer is known. Cationic active catalysts used in these copolymers include Lewis acids, especially boron, tin, titanium, phosphorus, arsenic and antimony halides such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, pentachloride. Compounds such as phosphorus fluoride, arsenic pentafluoride and antimony pentafluoride, and complex compounds or salts thereof; protic acids such as perchloric acid; esters of protic acids, especially esters of perchloric acid and lower aliphatic alcohols; For example perchloric acid-tertiary butyl ester; anhydrides of protonic acids, especially mixed anhydrides of perchloric acid and lower aliphatic carboxylic acids, such as acetyl perchlorate, or also trimethyloxonium hexafluorophosphate, triphenyl- Methyl hexafluoroarsenate, acetyl tetrafluoroborate, acetyl Kisa fluor phosphate and acetyl hexafluoroacetylacetone ARUZE diisocyanate and the like have been proposed. Among them, boron trifluoride or a coordination compound of boron trifluoride and an organic compound such as ether is the most common as a polymerization catalyst having trioxane as a main monomer and is widely used industrially.

  However, generally used polymerization catalysts such as boron trifluoride compounds require a relatively large amount of catalyst (for example, 40 ppm or more based on the total monomers) for polymerization. For this reason, it is difficult to sufficiently perform the catalyst deactivation treatment after polymerization, and even if the catalyst is deactivated, the substance derived from the catalyst remains in the copolymer, and the decomposition of the copolymer is promoted. Problems may arise. The catalyst deactivation step is generally performed in a large amount of an aqueous solution containing a basic compound such as triethylamine. After deactivation of the catalyst, the copolymer is separated from the treatment liquid and dried. This requires a complicated process such as recovering the dissolved unreacted monomer, and has a problem economically.

  In order to eliminate the complication associated with the deactivation treatment of the catalyst, a method of adding a trivalent phosphorus compound to the resulting copolymer (see, for example, Patent Document 1) or a method of adding a hindered amine compound (Patent Document) 2) has also been proposed, but not as much as expected.

  On the other hand, a method for producing a polyacetal copolymer using a heteropolyacid as a catalyst has been proposed (see, for example, Patent Document 3). In addition, after preparing a crude polyacetal copolymer by copolymerization using a heteropolyacid as a catalyst, the reaction product is a solid that is at least one selected from a triazine ring-containing compound having an amino group or a substituted amino group and a polyamide A method for producing a polyacetal copolymer in which a basic compound is added and a catalyst is deactivated by melt kneading has been proposed (see, for example, Patent Document 4). According to this method, since the heteropolyacid is highly active, polymerization is possible with a very small amount of catalyst, and a high-quality polyacetal copolymer can be provided. In addition, since the catalyst is deactivated by melt kneading without substantially using a solution, the complicated steps as described above are not required and the economy is excellent.

Japanese Patent Publication No. 55-42085 JP-A-62-257922 JP-A-1-170610 JP 2003-026746 A

  In recent years, there has been a demand for a high-quality polyacetal copolymer having particularly excellent thermal stability and an extremely small amount of formaldehyde generated. However, the methods described in Patent Documents 1 to 4 are difficult to meet the requirements. The situation is starting. In order to meet this requirement, further improvements such as more efficient deactivation of the catalyst and stabilization by more complete decomposition treatment of the unstable terminal portion of the crude polyacetal copolymer after deactivation of the catalyst are required. It has been demanded.

  An object of the present invention is to provide a facility and operating technique that can easily and efficiently deactivate a catalyst by a selection of a catalyst, a catalyst deactivator, an unstable terminal treating agent, or a selective combination thereof, and does not require a washing step. Provides a method for producing a stabilized polyacetal copolymer with a simple process, high polymerization yield, very little unstable terminal portion, extremely thermally stable, and extremely low formaldehyde emission That is.

  As a result of intensive studies on the type of catalyst and the corresponding catalyst deactivation method and unstable terminal treatment method in order to achieve the above-mentioned problems, the present inventor uses a heteropolyacid represented by the following general formula (1) as a catalyst. At the same time, a melt-kneading treatment using a guanidine compound represented by the following general formula (2) for catalyst deactivation and unstable terminal treatment ensures that the catalyst is lost even though the polymerization activity of the catalyst is high. It has been found that the active and unstable ends can be reduced and stabilized, and further, the equipment and operation technique can be easily achieved to achieve the above object, and the present invention has been completed. More specifically, the present invention provides the following.

(1) The present invention provides a polymerization catalyst for producing a polyacetal copolymer using trioxane as a main monomer (a) and a cyclic ether having at least one carbon-carbon bond and / or a cyclic formal as a comonomer (b). Copolymerization is performed using a heteropolyacid represented by the following general formula (1) in (c), and a guanidine compound (d) represented by the following general formula (2) is added to the reaction product, followed by melt-kneading treatment. And a method for producing a polyacetal copolymer, wherein the polymerization catalyst (c) is deactivated.

  (2) Further, in the present invention, the comonomer (b) is at least one selected from 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, or ethylene oxide. 1) A process for producing a polyacetal copolymer according to 1).

  (3) Further, in the present invention, the heteropolyacid may be phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silica The method for producing a polyacetal copolymer according to (1) or (2), wherein the polyacetal copolymer is at least one selected from molybdic acid, silicoribed tungstic acid, or silicoribed tungstovanadic acid.

  (4) In the present invention, the guanidine compound may be 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1,1,3,3-tetramethylguanidine, cyanoguanidine, phenylbiguanide, At least one selected from -o-tolylbiguanide, 1,5,7-triazabicyclo [4.4.0] dec-5-ene, glycosiamine, 2-aminopyrimidine, acetylacetoneguanidine or 2-aminobenzimidazole A method for producing a polyacetal copolymer according to any one of (1) to (3).

  (5) Further, in the present invention, a solution of the main monomer (a), the comonomer (b), and the polymerization catalyst (c) is mixed in advance in a liquid phase state, and then supplied to the polymerization apparatus. ) To (4). The method for producing a polyacetal copolymer according to any one of (4) to (4).

  (6) Moreover, this invention performs the deactivation of the said polymerization catalyst (c) by melt-kneading process in presence of antioxidant, (1) to the polyacetal copolymer in any one of (5) It is a manufacturing method.

  According to the present invention, it is possible to economically produce a high-quality polyacetal copolymer having excellent thermal stability and a very small amount of formaldehyde generated by a simple production process.

  In addition, according to the present invention, by using a dry method as compared with a conventional wet type deactivation method, the deactivation step is simplified and the cleaning step is omitted, and the polymerization process is extremely streamlined. The unstable end can also be stabilized following rapid and complete deactivation of the catalyst. As a result, it is possible to economically produce an excellent quality polyacetal copolymer that is free from decomposition and alteration caused by the catalyst, is thermally stable, and has a very low unstable terminal portion and formaldehyde release amount. it can.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

<Method for producing polyacetal copolymer>
In the present invention, a polyacetal copolymer is produced using trioxane which is a cyclic trimer of formaldehyde as a main monomer (a) and a cyclic ether having at least one carbon-carbon bond and / or a cyclic formal as a comonomer (b). In carrying out the copolymerization, the polymerization catalyst (c) is copolymerized using a predetermined heteropolyacid, the predetermined guanidine compound (d) is added to the reaction product, the mixture is melt-kneaded, and the polymerization catalyst (c) is lost. Make it live.

[Comonomer (b)]
As the comonomer (b), a compound selected from cyclic ether having at least one carbon-carbon bond and cyclic formal is used. Representative examples of the compound used as the comonomer (b) include, for example, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin and the like. It is done. Among these, in view of polymerization stability, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide and the like are preferable. Further, cyclic esters such as β-propiolactone and vinyl compounds such as styrene can be used. Moreover, it is also possible to use a monofunctional cyclic ether or cyclic formal having a substituent unit such as butyl glycidyl ether or 2-ethylhexyl glycidyl ether as a comonomer. Further, as a comonomer, a compound having two polymerizable cyclic ether groups or cyclic formal groups such as diglycidyl ether or diformal of alkylene glycol, for example, butanediol dimethylidene glyceryl ether, butanediol diglycidyl ether, A compound having three or more polymerizable cyclic ether groups or cyclic formal groups such as glycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether can also be used. Further, a polyacetal copolymer in which a branched structure or a crosslinked structure is formed is also included in the scope of the present invention.

  In the present invention, the amount of the compound (b) selected from cyclic ether and cyclic formal used as a comonomer is 0.1 to 20 mol% as a ratio in the total monomer (total amount of main monomer and comonomer), preferably 0.2 to 10 mol%. If it is less than 0.1 mol%, the unstable terminal part of the crude polyacetal copolymer produced by the polymerization will increase and the stability will deteriorate, and if the amount of comonomer is excessive, the produced copolymer will become soft and the melting point will decrease. It is not desirable to occur.

[Polymerization catalyst (c)]
One feature 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 heteropolyacid used as the polymerization catalyst (c) is a generic name for polyacids formed by dehydration condensation of different types of oxygen acids, and a specific different element exists at the center and shares an oxygen atom. And having a mononuclear or binuclear complex ion formed by condensation of condensed acid groups. Such heteronuclear condensed acid can be represented by the following general formula (1).

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

  Specific examples of the heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, Examples thereof include molybdotungstic acid and silicomolybdotungstovanadate. Among these, in view of the stability of polymerization and the stability of the heteropolyacid itself, the heteropolyacid is preferably at least one of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid or phosphotungstic acid.

In the present invention, the amount of the heteropolyacid used varies depending on the type thereof, and can be appropriately changed to control the polymerization reaction. It is in the range of 100 ppm (hereinafter referred to as weight / weight ppm), preferably 0.1 to 50 ppm. Further, for heteropolyacids such as phosphomolybdic acid and phosphotungstic acid that act very strongly, a use amount of 0.1 to 10 ppm is sufficient. The fact that copolymerization is possible even with such a small amount of catalyst keeps undesired reactions such as main chain decomposition and depolymerization of the polymer by the catalyst slight, and unstable formate end groups (—O—CH═O). It is effective in suppressing the formation of hemiacetal end groups (—O—CH ₂ —OH) and the like, and is also economically advantageous.

  In order to carry out the reaction uniformly, the polymerization catalyst is preferably diluted with an inert solvent that does not adversely influence the polymerization and added to the main monomer and / or comonomer. Examples of the inert solvent include low molecular weight carboxylic acids having 1 to 10 carbon atoms such as formic acid, acetic acid, propionic acid, butyric acid, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2 Obtained by condensation of low molecular weight alcohols having 1 to 10 carbon atoms such as methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 3-methyl-1-butanol, and 1-hexanol. Esters: Preferred are low molecular weight ketones having 1 to 10 carbon atoms such as acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, methyl isobutyl ketone, and methyl-t-butyl ketone. However, it is not limited to these. Considering industrial availability, methyl formate, ethyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, 2-butanone, methyl isobutyl ketone and the like are most suitable. The polymerization catalyst is preferably dissolved in the inert solvent at a concentration of 1 to 30% by weight / weight, but is not limited thereto. In addition, a predetermined amount of the polymerization catalyst is mixed in advance with a part or all of one or more of the main monomer, comonomer, molecular weight regulator, etc. described above, and this solution is added to the polymerization system for polymerization. The method of performing is also preferred.

[Preparation of copolymer]
In the present invention, the preparation of the crude polyacetal copolymer by polymerization can be carried out by the same equipment and method as those of conventionally known trioxane copolymerization. That is, any of a batch type, a continuous type, and a semi-continuous type is possible, and a method of using a liquid monomer and obtaining a solid lump-like polymer with the progress of polymerization is common. As a polymerization apparatus used in the present invention, a reaction vessel with a stirrer that is generally used in a batch type can be used, and as a continuous type, a kneader, a twin screw type continuous extrusion mixer, a biaxial paddle type continuous type is used. A mixer or other continuous polymerization apparatus such as trioxane proposed so far can be used, and two or more types of polymerization machines can be used in combination.

  The polymerization method is not particularly limited, but as previously proposed, trioxane, a comonomer, and a heteropolyacid as a polymerization catalyst are sufficiently mixed in advance while maintaining a liquid phase state, and a reaction raw material obtained is obtained. If the mixed solution is supplied to the polymerization apparatus to carry out the copolymerization reaction, the required amount of catalyst can be reduced, and as a result, it is advantageous to obtain a polyacetal copolymer with a smaller amount of formaldehyde emission, and a more suitable polymerization method It is. The polymerization temperature is performed in a temperature range of 60 to 120 ° C.

  In preparing the polyacetal copolymer by polymerizing the main monomer (a) and the comonomer (b) in the present invention, a low-molecular-weight line such as a known chain transfer agent such as methylal is used to adjust the degree of polymerization. Acetal or the like can also be added.

  The polymerization reaction is preferably carried out in a state in which impurities having active hydrogen, for example, water, methanol, formic acid and the like are substantially absent, for example, in a state where each of them is 10 ppm or less. It is desirable to use trioxane, cyclic ether and / or cyclic formal prepared so as not to contain as much as possible as the main monomer or comonomer.

[Guanidine Compound (d)]
The present invention provides a polyacetal copolymer (crude copolymer) obtained by copolymerization as described above, containing a polymerization catalyst and having an unstable portion at the terminal, by the following general formula (2). The guanidine compound (d) shown is added, melted and kneaded to deactivate the polymerization catalyst, and the unstable end groups of the polyacetal copolymer (crude copolymer) are reduced and stabilized. And Such stabilization treatment is performed by adding the guanidine compound (d) represented by the general formula (2) as it is without washing the crude polyacetal copolymer obtained by the copolymerization reaction, It can be performed more simply and efficiently.

In formula (2), R ¹ represents hydrogen or a phenyl group, and R ² , R ³ , R ⁴ and R ⁵ are each independent, hydrogen, methyl group, phenyl group, tolyl group, cyano group, alkylene group , An alkenyl group (which may have a methyl group), —C (═NH) NH ₂ or —CH ₂ —C (═O) OH. R ¹ and R ⁵ may or may not be chemically bonded. R ³ and R ⁴ may or may not be chemically bonded. Alternatively, R ⁴ and R ⁵ may be the same, that is, a double bond may be formed between N ⁴ and chemically bonded to R ¹ or not.

  Specific examples of the guanidine compound (d) include 1-phenylguanidine, 1,1′-diphenylguanidine, 1,3-diphenylguanidine, 1,2,3-triphenylguanidine, 1,1-dimethyl-2,3. -Diphenylguanidine, 1,1,3,3-tetramethylguanidine, biguanide, phenylbiguanide, 1-o-tolylbiguanide, 1,1'-di-o-tolylguanidine, 1,3-di (o-tolyl) Guanidine, cyanoguanidine, glycosamine, 1,5,7-triazabicyclo [4.4.0] dec-5-ene (also referred to as “TBD”), 2-aminopyrimidine, acetylacetoneguanidine, 2-amino Benzimidazole, 5-amino-2- (4-aminophenyl) -1H-benzimidazole, 2-guanidino-1 - Although benzimidazole, and the like, but is not limited thereto. Considering industrial availability and the like, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1,1,3,3-tetramethylguanidine, cyanoguanidine, phenylbiguanide, 1- o-tolylbiguanide, 1,5,7-triazabicyclo [4.4.0] dec-5-ene (also referred to as “TBD”), glycosylamine, 2-aminopyrimidine, acetylacetoneguanidine, 2-amino Benzimidazole and the like are most preferred.

  In the present invention, the guanidine compound (d) represented by the general formula (2) may be one kind or a combination of two or more.

The content of the guanidine compound (d) is generally 0.005 to 3.5 mmol in terms of guanidine skeleton (R ^{1 to} R ⁵ are hydrogen) with respect to ¹ kg of the crude polyacetal copolymer. The amount is preferably 0.01 to 3.0 mmol, particularly preferably 0.02 to 2.5 mmol. However, the amount of the unstable end group generated by the catalyst amount (particularly, the amount of catalyst remaining in the polymer) and various polymerization conditions It is preferable to change the addition amount as appropriate according to the type and amount, and it is desirable to adjust the addition amount depending on the degree of activity of the guanidine compound (d) used and the processing conditions (temperature, time, contact speed, etc.). . The biguanide was considered to be composed of two guanidine skeletons.

[Deactivation of catalyst]
In the present invention, it is preferable that the amount of unreacted monomer is smaller when the catalyst is deactivated after the polymerization. The unreacted monomer (representing the total of the main monomer and the comonomer) is 10% by weight or less in the crude copolymer. Further, it is 5% by weight or less, particularly preferably 3% by weight or less. As a result, a particularly desirable aspect of the present invention can be achieved in which the crude polyacetal copolymer produced by polymerization is treated without washing. In order to reduce unreacted monomers, it is generally sufficient to increase the polymerization rate above a certain level. In the case of the present invention, this is achieved by appropriately adjusting the amount of catalyst used and the polymerization time (residence time in the continuous system). Since a heteropolyacid catalyst that is easily achieved and has high activity is used, even a small amount of catalyst can be achieved in a relatively short time. Further, after the copolymerization reaction, a part of the residual monomer may be removed by evaporation and vaporization so that a predetermined residual monomer amount is obtained. In addition, during or after the copolymerization, the unreacted trioxane and comonomer recovered as a gas can be liquefied and reused as a part of the raw material monomer as it is. is there.

  If necessary, a conventionally known catalyst deactivator or unstable terminal decomposition treatment agent can be used in combination with the guanidine compound (d).

  In the present invention, the addition of the guanidine compound (d) represented by the general formula (2) functioning as a quenching agent / stabilizing agent is performed at any stage before or after melting the crude polyacetal copolymer. It may be performed at both stages. Moreover, as a method for adding the guanidine compound (d) represented by the general formula (2), it may be divided and supplied in multiple stages.

  In addition, as a method of adding the guanidine compound (d) represented by the general formula (2) as the deactivation / stabilizing agent to the crude copolymer before melting, a predetermined amount of the crude copolymer as much as possible is possible. Mix evenly after addition. For mixing, a general mixer such as a horizontal cylindrical type, a V type, a ribbon type, a paddle type, or a high-speed flow type can be used. The mixture may be melted as it is, or may be melted after the solvent is distilled off by heating, decompression or the like. Further, the deactivation / stabilizer solution may be supplied by injection or the like from the feed port of the extruder and / or midway. At this time, the deactivation / stabilizer solution may be divided and supplied in multiple stages.

  After melting the crude copolymer, the deactivation / stabilizer is added to the molten polyacetal resin by feeding and / or injecting the deactivation / stabilizer and the solvent separately or in solution. can do.

  Further, the guanidine compound (d) represented by the general formula (2) is dissolved in water, added to the crude copolymer as an aqueous solution to form a slurry, filtered and dried, and then the deactivation / stabilizer is added to the crude copolymer. A treating agent can also be added by the method of making it adhere.

  In addition, when the guanidine compound (d) represented by the general formula (2) is added as a deactivation / stabilization treatment agent, it is preferable that the crude copolymer is a fine granular material. Although it is preferable that the machine has a function of sufficiently pulverizing the block polymer, the reaction product after polymerization may be separately pulverized using a pulverizer. As for the particle size of the crude copolymer in the deactivation treatment, at least 90% by weight or more is 10 mm or less, preferably 4 mm or less, more preferably 2 mm or less.

  The melt-kneading apparatus is not particularly limited, but has a function of kneading the melted copolymer, and preferably has a vent function, for example, a uniaxial or multiaxial continuous having at least one vent hole. Examples include an extrusion kneader and a kneader. In the melt-kneading process of the present invention, the polymerization catalyst is completely deactivated and unstable terminals are reduced and stabilized. The temperature range from the melting point of the copolymer to 260 ° C. is preferable for the melt-kneading treatment. When the temperature is higher than 260 ° C., the polymer is degraded and deteriorated.

  In the present invention, the melt kneading treatment is preferably performed in the presence of an antioxidant. As the antioxidant, known substances such as various hindered phenol antioxidants are used as stabilizers for conventional polyacetal resins. For example, 2,6-di-tert-butyl-4-methylphenol, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexane Diol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxyhydrocinnamide), 2-t-butyl-6- (3′-t-butyl-5′-methyl-2 ′) -Hydroxybenzyl) -4-methylphenyl acrylate, 3,9-bis [2-{(3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1'-di Chiruechiru] -2,4,8,10-spiro [5,5] - undecane, and the like. These hindered phenolic antioxidants may be polymerized by adding a part or all of them in advance to the main monomer or comonomer before polymerization. Is not particularly excessive, there is no adverse effect on the activity of the polymerization catalyst, which is one of the preferred embodiments.

  Further, at this stage, if necessary, a known substance may be added as a stabilizer for various polyacetal resins. Further, for example, an inorganic filler such as glass fiber, a crystallization accelerator (nucleating agent), a release agent, an antioxidant and the like may be added.

  As described above, the guanidine compound (d) represented by the general formula (2) is added to the crude copolymer as a deactivation / stabilization treatment agent, melt-kneaded, and then usually decomposed to formaldehyde gas. Unreacted monomers, oligomers, deactivators / stabilizers and the like are removed from the vent portion of the extruder under reduced pressure and formed into pellets or the like to obtain products for resin processing. The pellets are dried as necessary. In the case of drying, for example, it is dried at 135 ° C. for about 4 hours.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and demonstrated concretely, this invention is not limited to these Examples.

<Examples 1-15>
[Copolymerization of trioxane as main monomer (a) with cyclic ether and / or cyclic formal as comonomer (b)]
A continuous biaxial polymerization machine was used as the polymerization reactor. This polymerization machine has a jacket for passing a heating or cooling medium on the outside, and two rotating shafts with a large number of paddles for stirring and propulsion are provided in the longitudinal direction in the inside. ing. As a main monomer (a) containing warm water of 80 ° C. through the jacket of this biaxial polymerization machine and rotating two rotating shafts at a constant speed and containing 1200 ppm of methylal as a chain transfer agent at one end thereof. A mixture containing 96.5% by weight of trioxane and 3.5% by weight of the comonomer (b) shown in Table 1 was continuously fed, and Table 1 was used as a polymerization catalyst (c). The methyl formate solution containing 0.3% by weight of the heteropolyacid shown in FIG. In Table 1, the addition amount of the polymerization catalyst is a weight ratio (unit: ppm) to the total of all monomers.

[Deactivation of polymerization catalyst (c)]
The reaction product by copolymerization is discharged from a discharge port provided at the other end of the polymerization machine, and a guanidine compound (d) represented by the general formula (2) shown in Table 1 is added to deactivate the catalyst. did. Next, 0.3% by weight of triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyfehl) propionate] was added as an antioxidant, and a vented twin screw extruder was used. Then, the mixture was melt kneaded and extruded at a temperature of 220 ° C. and a degree of vacuum of 5 mmHg in the vent portion to prepare polyacetal copolymer pellets according to Examples 1-15.

<Comparative Example 1>
In the same manner as in Example 1, except that a cyclohexane solution of boron trifluoride butyl etherate 0.5% by weight was used as a polymerization catalyst and a known triphenylphosphine was used as a deactivator. A pellet of polyacetal copolymer according to Example 1 was prepared. When the polymerization catalyst is boron trifluoride dibutyl etherate, the addition amount of the polymerization catalyst is a value as boron trifluoride (BF ₃ ).

<Comparative example 2>
Polymerization was carried out in the same manner as in Example 1 using a cyclohexane solution containing 0.5% by weight of boron trifluoride butyl etherate as a polymerization catalyst. The reaction product discharged from the discharge port is introduced into a 0.1% by weight aqueous solution of triethylamine to prepare a slurry containing 20% by weight of the reaction product, and stirred at 80 ° C. for 1 hour to deactivate the catalyst. Then, it filtered and dried at 100 degreeC for 1 hour. Subsequently, the polyacetal copolymer according to Comparative Example 2 was added by adding 0.3% by weight of triethylene glycol-bis [3- (3-t-butyl-5-methyl-1-hydroxyphenyl) propionate] as an antioxidant. Combined pellets were prepared.

<Comparative Example 3>
Polymerization was carried out in the same manner as in Example 1 using the types and amounts of heteropolyacids shown in Table 1. The reaction product discharged from the discharge port was treated in a slurry state in the same manner as in Comparative Example 2, and further extruded by adding an antioxidant. Thereby, the pellet of the polyacetal copolymer which concerns on the comparative example 3 was prepared.

<Evaluation>
The pellets of the polyacetal copolymer according to Examples and Comparative Examples were dried at 135 ° C. for 4 hours, and then measured for melt index (MI), alkali decomposition rate and formaldehyde emission.

[Evaluation of Melt Index (MI)]
Melt index measuring device: Melt Index L202 type (manufactured by Takara Thermistor) was used as a melt index (g / 10 min) when measured under conditions of a load of 2.16 kg, a temperature of 190 ° C. and 7 minutes. The results are shown in Table 2. In this example, the melt index (MI) is a characteristic value corresponding to the molecular weight. That is, the lower the MI, the higher the molecular weight, and the higher the MI, the lower the molecular weight. In this example, when MI is less than 10 g / 10 min, it is determined that the polymerization catalyst has been sufficiently deactivated. When MI is 10 g / 10 min or more, the polymerization catalyst is sufficiently deactivated. It was judged that it was not done.

[Evaluation of alkali decomposition rate (abundance of unstable part)]
The copolymer pellets in Examples and Comparative Examples were pulverized, and about 1 g thereof was precisely weighed and sealed in a sealable container together with 100 mL of 50% aqueous methanol solution containing 0.5% by weight of ammonium hydroxide. 180 After heating at ° C for 45 minutes, the amount of formaldehyde decomposed and eluted in the liquid was quantitatively analyzed. The results are shown in Table 2. The alkali decomposition rate is shown as a ratio (unit:%) to 100% by weight of the copolymer pellets.

[Evaluation of formaldehyde emission]
Samples in Examples and Comparative Examples were filled in a cylinder maintained at 200 ° C., melted in 5 minutes, and then the melt was extruded from the cylinder into a sealed container. Nitrogen gas was allowed to flow through this sealed container, and formaldehyde contained in the nitrogen gas that had come out was dissolved and collected in water, and the formaldehyde concentration in the water was measured to determine the weight of formaldehyde released from the melt. The formaldehyde weight was divided by the weight of the melt to obtain formaldehyde emission (unit: ppm). The results are shown in Table 2.

  In the present invention, the polymerization catalyst is a heteropolyacid represented by the above general formula (1), and the deactivator for this heteropolyacid is the guanidine compound (d) represented by the above general formula (2). It was confirmed that a high polymerization yield was obtained, and after polymerization, the above-mentioned guanidine compound was added to the crude copolymer, and an extremely high-quality polyacetal copolymer could be provided as a product simply by melt-kneading ( Examples 1-15).

  In addition, when the polymerization catalyst is boron trifluoride, not only a large number of steps are required to complete the deactivation due to the large amount of the catalyst, but also the substance derived from the catalyst after the deactivation treatment. It was confirmed that harmful effects such as decomposition were difficult to avoid (Comparative Examples 1 and 2). In addition, when the deactivator of the polymerization catalyst is triethylamine, the polymerization catalyst cannot be sufficiently deactivated as in the examples, the alkali decomposition rate is high, and the quality of the polyacetal copolymer is inferior to the examples. Was confirmed (Comparative Examples 2 and 3). Also, when the polymerization catalyst deactivator is triethylamine, in order to use a large amount of triethylamine aqueous solution, after deactivation of the catalyst, the copolymer is separated from the treatment liquid and dried, and unreacted monomer dissolved in the treatment liquid is recovered. This requires a complicated process, such as to do, and remains a problem economically.

Claims (6)

In producing a polyacetal copolymer using trioxane as a main monomer (a) and a cyclic ether having at least one carbon-carbon bond and / or a cyclic formal as a comonomer (b), the polymerization catalyst (c) has the following general formula. Copolymerization is carried out using the heteropolyacid represented by (1), a guanidine compound (d) represented by the following general formula (2) is added to the reaction product, and melt-kneading treatment is carried out to obtain a polymerization catalyst (c). The manufacturing method of the polyacetal copolymer which deactivates.

  The polyacetal copolymer according to claim 1, wherein the comonomer (b) is at least one selected from 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, or ethylene oxide. Manufacturing method.   The heteropolyacids are phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, lintonguestovanadic acid, silicotungstic acid, silicomolybdic acid, and silicomolybdotungstic acid. Or the manufacturing method of the polyacetal copolymer of Claim 1 or 2 which is at least 1 sort (s) selected from the moss-rib-tungstovanadic acid.   The guanidine compound includes 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1,1,3,3-tetramethylguanidine, cyanoguanidine, phenylbiguanide, 1-o-tolylbiguanide, 1, It is at least one selected from 5,7-triazabicyclo [4.4.0] dec-5-ene, glycosylamine, 2-aminopyrimidine, acetylacetone guanidine or 2-aminobenzimidazole. The manufacturing method of the polyacetal copolymer in any one.   The solution of the main monomer (a), the comonomer (b), and the polymerization catalyst (c) is mixed in advance in a liquid phase state and then supplied to a polymerization apparatus. A method for producing a polyacetal copolymer.   The method for producing a polyacetal copolymer according to any one of claims 1 to 5, wherein the polymerization catalyst (c) is deactivated by melt kneading in the presence of an antioxidant.