JP2958277B2 - Method for producing polyacetal copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyacetal copolymer. Specifically, in the copolymerization of trioxane as a main monomer with a co-monomer that can be copolymerized with the same, a heteropolyacid or an acid salt thereof is used as a polymerization catalyst, and a polyacetal copolymer having excellent quality such as thermal stability can be obtained in a simple process. The present invention relates to a method for producing a united product.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a polyacetal copolymer, cationic copolymerization using trioxane as a main monomer and a cyclic ether or cyclic formal having two or more adjacent carbon atoms as a comonomer has been known. Cationic active catalysts used in these copolymers include Lewis acids, particularly boron, tin, titanium, phosphorus, arsenic and antimony halides, such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, Compounds such as phosphorus fluoride, arsenic pentafluoride and antimony pentafluoride and their complex compounds or salts, protonic acids, for example perchloric acid, esters of protic acids, especially esters of perchloric acid with lower aliphatic alcohols, for example Perchloric acid-tertiary butyl ester, an anhydride of a protonic acid, particularly a mixture of perchloric acid and a lower aliphatic carboxylic acid Condensed anhydrides, for example acetyl perchlorate or also trimethyloxonium hexafluorophosphate, triphenyl-methylhexafluoroalzenate, acetyltetrafluoroborate, acetylhexafluorophosphate and acetylhexafluoroalzenate Etc. have been proposed. Among them, boron trifluoride or a coordination compound of boron trifluoride and an organic compound such as ethers is the most common as a copolymerization catalyst having trioxane as a main monomer, and is widely used industrially. . However, a generally used polymerization catalyst such as a boron trifluoride-based compound requires a relatively large amount (for example, 40 ppm or more based on all monomers), and after the polymerization, it is difficult to sufficiently deactivate the catalyst. Decomposition is promoted due to the remaining of the substance derived from the catalyst even when the reaction is carried out, and the polymerization yield and the degree of polymerization are limited.In addition, a considerable amount of an unstable terminal is present, and a complicated stabilization step is performed. There were problems such as the need. That is, in the conventional method for copolymerizing trioxane with a catalyst as described above, it is important to deactivate the catalyst after polymerization, and if this is insufficient, it promotes the decomposition of the produced polymer, and the subsequent production of the produced polymer. It is a major cause of stability degradation. Conventionally, when boron trifluoride or the like is used as a catalyst, in order to sufficiently deactivate the catalyst, a large amount of a deactivator solution is added to the product after polymerization, and deactivation is performed. To remove residual monomers and residues derived from the catalyst, and then separate, dry,
Alternatively, an extremely complicated process is required, for example, the monomer needs to be recovered from the washing solution, which is not economically preferable. Further, in order to reduce the complexity associated with the catalyst deactivation treatment, there has been proposed a method of performing a catalyst deactivation treatment by bringing the produced copolymer into contact with a gaseous deactivator (see, for example, Japanese Patent Application Laid-Open No. H11-163873). 1983-167608
And JP-A-2-263813), all of these methods are intended for conventionally known polymerization catalysts such as boron trifluoride-based catalysts. Sufficient deactivation cannot be performed, and it is extremely difficult to obtain a copolymer having good thermal stability. In particular, when the polymerization yield during polymerization is increased, the produced polymer becomes more unstable, and a complicated stabilization treatment is required in the subsequent steps, which does not result in simplification of the steps and also in the stability. There is a limit and it is not desirable in quality.

[0003]

In view of the above situation, the present inventors can easily deactivate a catalyst by contacting it with a basic gas, and a simple process that does not require a washing step. Moreover, it is an object of the present invention to produce a polyacetal copolymer which can completely deactivate the catalyst, has a very small number of unstable terminal portions even at a high polymerization yield, and is extremely thermally stable.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies on the type of catalyst and the corresponding deactivation method in order to achieve the above object, and have found that a heteropolyacid or an acid salt thereof is particularly used as a catalyst. Therefore, as a characteristic of the catalyst, despite the high polymerization activity, the catalyst can be very easily and reliably deactivated by contacting with a gaseous deactivator. It was found that the present invention was obtained, and the present invention was completed. That is, the present invention, the trioxane as a main monomer, at least one carbon as a comonomer - polyacetal copolymerization by the copolymerization of <br/> Ru cyclic ether or cyclic formal having a carbon binding as part of the ring components In producing the union, copolymerization is carried out using a heteropolyacid represented by the following general formula (1) or an acid salt thereof as a polymerization catalyst, and after copolymerization, the remaining monomer is reacted.
To 10% by weight or less based on the total amount of monomers supplied, then contact a basic gas as a catalyst deactivator with the produced polymer to deactivate the catalyst, and then heat and melt the crude polymer without washing it The present invention relates to a method for producing a polyacetal copolymer, which is characterized by treating.

[0005]

Embedded image

The feature of the present invention is that the use of a heteropolyacid or an acid salt thereof as a polymerization catalyst makes it possible to obtain a very high polymerization activity in a very small amount and to obtain a high polymerization yield. , The deactivation can be performed very reliably and effectively. Even if the substance derived from the catalyst remains, there is no harm at all, the washing step, etc. are unnecessary, and the polymer is heated and melted as it is. To obtain a polyacetal copolymer having very few unstable parts and being extremely stable thermally. This is because, in the case of a conventional boron trifluoride-based catalyst, etc., the deactivation becomes insufficient, and it tends to remain active especially in contact with a gaseous deactivator, and is derived from the catalyst even after the deactivation treatment. While it is difficult to avoid harmful effects such as decomposition by substances, it has a special effect.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below. First, the heteropolyacid of the copolymerization catalyst, which is a feature of the present invention, is a general term for polyacids formed by dehydration condensation of different oxyacids. It has a mononuclear or polynuclear complex ion formed by condensation of acid groups. Such a heteronuclear condensed acid can be generally represented by the general formula (1). The heteropolyacid particularly effective as the copolymerization catalyst of the present invention is such that the central element (M) in the above composition formula is composed of one or two elements selected from P and Si, and a coordination element ( M ′) is composed of one or more elements selected from W, Mo and V (particularly preferably W and Mo). Further, an acidic salt in which Hx in the formula (1) is partially replaced by various metals or the like can also be used for the catalyst of the present invention. Specific examples of these heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdung tungstovanadic acid, phosphorus tungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicic acid Molybdung tungstic acid, silico-molybdung tovanadic acid, and the like. Among them, preferred are silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, phosphotungstic acid and the like. The amount of the heteropolyacid or the acid salt thereof used as a polymerization catalyst for a monomer mainly containing trioxane varies depending on the kind thereof, and the polymerization reaction can be appropriately changed to control the polymerization reaction. It is in the range from 0.05 to 100 ppm, preferably from 0.1 to 50 ppm, based on the total amount of monomers to be used. A very strong acting heteropolyacid such as phosphomolybdic acid, phosphotungstic acid, etc., is preferably used in an amount of 0.1 to 10 ppm. The fact that copolymerization is possible even with such a small amount of catalyst means that undesired reactions such as decomposition of the main chain of the polymer and depolymerization by the catalyst are minimized, and unstable formate end groups (-O-CH = O) And hemiacetal terminal groups (—O—CH ₂ —OH) and the like, and is economically advantageous. In the present invention, the catalyst is diluted with an inert solvent having no adverse effect on polymerization and added to the monomer, and it is desirable to use the catalyst in order to uniformly perform the reaction.As the diluent, a heteropolyacid or an acid thereof is used. ethers organic solvents salts are soluble, for example, n- but-butyl ether, or the like are preferred diluents is not limited thereto, the some or all of such comonomer and molecular weight modifier later It is also a preferable method to add a predetermined amount to the polymerization system as a previously dissolved solution. When the comonomer is also used as a diluent for the catalyst, in order to prevent the comonomer itself from being homopolymerized before addition, the temperature is kept low until immediately before addition to the polymerization system, for example, at least room temperature or lower, preferably 0 ° C or lower. It is desirable.

As the main monomer of the present invention, trioxane which is a cyclic trimer of formaldehyde is used.
The comonomer used in the present invention is at least one charcoal.
Element-carbon bond, that is, a bond between adjacent carbon atoms is part of a ring component.
A cyclic ether or cyclic formal having as
Any of the known comonomers used for conventional copolymerization with trioxane can be used. Representative examples of such a cyclic ether or cyclic formal include, for example, 1,3-
Dioxolan, diethylene glycol formal, 1,4
-Butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin and the like. Further, cyclic esters such as β-propiolactone and vinyl compounds such as styrene are also used. Further, a compound having two or more polymerizable cyclic ether groups or cyclic formal groups such as alkylene-diglycidyl ether or diformal can also be used as a comonomer in which the copolymer forms a branched or crosslinked molecular structure. . For example, butanediol dimethylidene glyceryl ether, butanediol diglycidyl ether and the like can be mentioned. In particular, the comonomer is preferably a cyclic ether or cyclic formal such as 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, and ethylene oxide.
The amount of comonomer used in the present invention is based on trioxane.
It is 0.1 to 20 mol%, preferably 0.2 to 10 mol%. If it is less than 0.1 mol%, the unstable terminal portion increases and the stability deteriorates. If it is too large, the produced copolymer becomes soft and the melting point is lowered, which is not preferable.

In the polymerization method of the present invention, it is also possible to add a known chain transfer agent, for example, a low molecular weight linear acetal such as methylal, for adjusting the degree of polymerization according to the purpose. In addition, the polymerization reaction system is desirably substantially free of impurities having active hydrogen, such as water, methanol, formic acid, etc., for example, each of which is preferably 10 ppm or less.

The polymerization method of the present invention can be carried out by the same equipment and method as in the conventionally known trioxane copolymerization.
That is, any of a batch type and a continuous type is possible, and a method of using a liquid monomer and obtaining a polymer in the form of a solid powder as the polymerization proceeds is general. As a polymerization apparatus used in the present invention, a reaction vessel with a stirrer generally used in a batch type can be used, and as a continuous type, a co-kneader, a twin-screw type continuous extruder and a twin-screw paddle type continuous mixing can be used. A continuous polymerization apparatus such as a trioxane or the like proposed so far can be used, and two or more types of polymerization apparatuses can be used in combination. The polymerization temperature is in the temperature range of 60 to 120 ° C,
Particularly, the range of 65 to 100 ° C is preferable. In the present invention,
The amount of unreacted monomer is preferably as small as possible in deactivating the catalyst after the polymerization, for example, 10% by weight or less, further 5% by weight or less, particularly preferably 3% by weight or less. Since the main object of the present invention is not to wash the polymerization product, it is not preferable that the residual monomer is large. In order to reduce the amount of unreacted monomer, it is generally sufficient to raise the polymerization rate to a certain level or more. In the case of the present invention, this is easily achieved by appropriately adjusting the amount of the catalyst used and the polymerization time (residence time in a continuous system). In particular, according to the catalyst of the present invention, its activity is high, so that it can be achieved in a relatively short time even with a small amount of catalyst. Further, after the polymerization reaction, a part of the residual monomer may be removed by evaporation and vaporization to obtain a predetermined residual monomer amount.

Next, the crude polymer after the copolymerization reaction is brought into contact with a basic gas as a deactivator to deactivate the catalyst.
The amount of the basic gas in the present invention may be an amount sufficient to neutralize and deactivate the catalyst, and is preferably at least 10 times the molar amount of the normally used catalyst. Examples of the basic gas used in the present invention include ammonia or an amine compound. The amine compound has the general formula R ₁ NH ₂ , R ₁ R ₂ NH and R ₁ R ₂ R ₃
A compound represented by N (wherein R ₁ , R ₂ and R ₃ are an alkyl group having 4 or less carbon atoms or an alcohol group) is preferable. Since the present invention is characterized in that the quenching agent is brought into contact with the produced crude polymer in a gaseous state, the amine compound has a relatively low molecular weight and preferably has a low boiling point, and the R ₁ , R ₂ , R ₃ is particularly preferably at most 2 carbon atoms, and can be contacted in gaseous form in relatively high-boiling amine by using is diluted with a carrier gas as described later.
Specific examples of the amine compound include, for example, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, butylamine, dibutylamine, tributylamine, and the corresponding alcoholamine (eg, trimethanolamine). Among them, methylamine, dimethylamine and trimethylamine are particularly preferred. Further, the above basic gas may be used alone, or may be brought into contact with the produced polymer by using a mixed gas diluted with another carrier gas. The carrier gas is not particularly limited, but is preferably an inert gas, such as a nitrogen gas or another organic gas. The method of contacting the basic gas with the crude polymer is not particularly limited as long as the basic gas can sufficiently contact the produced copolymer particles. For example, a method of stirring and mixing a crude polymer well under a basic gas atmosphere, a method of blowing a basic gas in opposition to a flow of a crude copolymer, a method of circulating and flowing between particles of a crude polymer layer, Either can be applied.

In the deactivation treatment of the catalyst, the coarse polymer is preferably a fine powder, and for this purpose, it is preferable that the polymerization reactor has a function of sufficiently pulverizing the bulk polymer. The reaction product after polymerization may be separately pulverized using a pulverizer and then brought into contact with a basic gas, or pulverization and stirring may be performed simultaneously in the presence of a basic gas. In the deactivation treatment, at least 90% or more of the coarse polymer has a particle size of 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less.
The particle size is preferably as follows. Deactivation temperature is 0
140 ° C, preferably 20 to 120 ° C.

In the present invention, the crude polymer which has been brought into contact with a basic gas to deactivate the catalyst is then subjected to a heating and melting treatment without washing. The heat melting treatment is preferably performed in the presence of a stabilizer. In general, the stabilizer may be added and mixed at any time after the polymerization and before the heat melting treatment, or may be added during the heat melting treatment. In a preferred embodiment, the heat melting treatment is performed by adding a small amount of water (for example, 0.1 to 5% by weight). As a stabilizer, it is important to add a substance known as a stabilizer of a conventional polyacetal resin, for example, various hindered phenolic antioxidants, etc., and various nitrogen-containing compounds, metal oxides and fatty acid salts. May be added and used in combination. For example, hindered phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl). ) Propionate], 1,6-hexanediol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], tetrakis [3
-(3,5-di-t-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-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1'-dimethyl Ethyl] -2,4,8,10-tetraoxaspiro [5,5] -undecane, and the like.
In addition, these hindered phenolic antioxidants may be added in advance to a comonomer such as trioxane or dioxolane before polymerization, and may be present at the time of polymerization. The agent does not adversely affect the activity of the polymerization catalyst unless the addition amount is particularly excessive, and is one of the preferred embodiments. Examples of the nitrogen-containing compound include dicyandiamide, melamine or a derivative thereof, urea or a derivative thereof, a benzotriazole-based compound, a piperidine-based compound (hindered amine), various polyamides, and copolymers thereof (for example, nylon 6, 12, 6). / 12, 6/66/610, 6/66/610 /
12 etc.). The metal oxide is preferably an oxide of an alkaline earth metal, and the metal fatty acid salt is, for example, a calcium salt or a magnesium salt of a higher fatty acid. Further, at this stage, various other additives such as a filler such as glass fiber, a crystallization accelerator (nucleating agent), and a release agent may be added and blended as needed.

The heating and melting treatment in the present invention is preferably carried out in a temperature range from the melting point of the produced polymer to 250 ° C., particularly preferably in a temperature range from the melting point to 230 ° C. 250 ℃
If it is higher, the polymer is decomposed and deteriorated, which is not preferable. Although there is no particular limitation on the heat treatment device, a device having a function of kneading a molten polymer and a device having a vent function is required, for example, a single-screw or multi-screw continuous extrusion having at least one vent hole. A kneader, a kneader and the like can be mentioned. In the present invention, in this melt-kneading treatment, the polymerization catalyst is completely deactivated, and a basic gas as a deactivator or an adsorbed product thereof is decomposed and desorbed from an unstable terminal of the crude polymer. Is promoted, and is removed from the vent portion together with other volatile substances, so that stable polyacetal copolymer pellets can be obtained. For this purpose, it is natural that it is preferable to reduce the pressure in the vent hole and to perform suction.

[0015]

EXAMPLES Examples of the present invention will be described below, but it is needless to say that the present invention is not limited to these examples. The terms and measuring methods in Examples and Comparative Examples are as follows. % Or ppm: All are expressed by weight. -Residual monomer: Indicates the residual monomer% with respect to all the monomers supplied. Melt index (MI): Shows the melt index (g / 10min) measured at 190 ° C. This was evaluated as a characteristic value corresponding to the molecular weight. That is, the lower the MI, the higher the molecular weight. -Alkali decomposition rate (amount of unstable portion): Copolymer pellets were pulverized, and 1 g thereof was placed in 100 ml of a 50% aqueous methanol solution containing 0.5% ammonium hydroxide and heated at 180 ° C for 45 minutes in a closed vessel. Thereafter, the amount of formaldehyde decomposed and eluted in the liquid is quantitatively analyzed, and the result is shown as% of the polymer. Heating weight reduction rate: 5 g of copolymer pellets in air
It shows the weight loss rate when heated at 230 ° C for 45 minutes. Examples 1 to 14, Comparative Examples 1 and 2 A barrel with a jacket that has a cross section in which two circles partially overlap each other and through which a heat (cooling) medium passes, and a number of paddles for stirring and propulsion inside the barrel. Using a continuous mixing reactor provided with two attached rotating shafts in the longitudinal direction, hot water of 70 ° C. was passed through the jacket, and the two rotating shafts were rotated at a constant speed. Trioxane containing 3.5% of the indicated comonomer and 700 ppm of methylal as a chain transfer agent was continuously supplied, and at the same time, a heteropolyacid catalyst shown in Table 1 (solution dissolved in di-n-butyl ether).
Was continuously added to all monomers in the amount shown in Table 1,
Copolymerization was performed. Next, the reaction product discharged from the discharge port of the polymerization machine is further polymerized by another apparatus (partially collected and the amount of residual monomer is measured), and then pulverized through a pulverizer (90% or more of the particles are granulated). (A diameter of 2 mm or less) and a basic gas shown in Table 1 at 80 ° C. for 30 minutes. Then, tetrakis- [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane is used as a stabilizer.
After adding 0.5% and melamine 0.2%, stirring and mixing in a Henschel mixer for 5 minutes, the mixture is melt-kneaded using a vented twin screw extruder at a temperature of 210 ° C. and a vacuum of 5 mmHg at the vent to extrude to form pellets. did. After drying the pellet, MI measurement, thermal decomposition rate measurement, and heating weight loss rate measurement were performed. Table 1 shows the results. For comparison, the same procedure was carried out for the case where boron trifluoride butyl etherate was used as a catalyst (Table 2).

Examples 15 to 17 In the above examples, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (0.2% based on all monomers) was used as an antioxidant. %) Was dissolved in a comonomer (1,3-dioxolane), and a heteropolyacid catalyst shown in Table 3 was further dissolved in this comonomer (0 ° C.), and this was added to trioxane for polymerization (other conditions were as follows). Almost the same as the above embodiment). Table 3 shows the results.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

As is clear from the above description and the examples, according to the manufacturing method of the present invention, compared with the conventional method,
In a very simplified process in which the washing process is omitted, complete deactivation of the polymerization catalyst can be performed, and there is no problem such as decomposition and alteration caused by the catalyst, and there is a stable and less unstable portion. A polyacetal copolymer is obtained, and a polyacetal copolymer of excellent quality can be economically produced.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 2/00-2/38

Claims (10)

(57) [Claims] The method according to claim 1] trioxane as a main monomer, at least one carbon as a comonomer - carbon binding ring structure essential
In producing a polyacetal copolymer by copolymerization with a cyclic ether or cyclic formal having a part of the element , copolymerization is performed using a heteropolyacid represented by the following general formula (1) or an acid salt thereof as a polymerization catalyst. Do
After copolymerization, the residual monomer is 10 weight
% Or less, then contact a basic gas as a catalyst deactivator with the produced polymer to deactivate the catalyst, and then heat-melt the crude polymer without washing it without washing. A method for producing a polymer. Embedded image 2. The method for producing a polyacetal copolymer according to claim 1, wherein the comonomer is at least one selected from 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, and ethylene oxide. 3. The heteropolyacid represented by the general formula (1) or an acid salt thereof is phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdenum vanadic acid, phosphorus tungstic acid The polyacetal copolymer according to claim 1 or 2, wherein the polyacetal copolymer is at least one compound selected from vanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdenum tungstic acid, silicomolybdenum tungstovanadic acid, or an acid salt thereof. Production method. 4. The method for producing a polyacetal copolymer according to claim 1, wherein the basic gas as a catalyst deactivator is ammonia. 5. The method for producing a polyacetal copolymer according to claim 1, wherein the basic gas as a catalyst deactivator is an amine compound. 6. An amine compound represented by the general formula R ₁ NH ₂ , R ₁ R ₂ NH and R ₁ R ₂ R ₃ N (wherein R ₁ , R ₂ and R ₃ are alkyl groups having 4 or less carbon atoms, 6. A compound represented by the formula:
A method for producing the polyacetal copolymer according to the above. 7. The catalyst is deactivated by contacting a basic gas as a catalyst deactivator as it is or as a mixed gas diluted with a carrier gas with a produced copolymer.
The method for producing a polyacetal copolymer according to any one of the above. 8. The method according to claim 1, wherein after the copolymerization, the residual monomer is reduced to 5 % by weight or less based on the total amount of the supplied monomers, and then the catalyst is deactivated by contacting with a basic gas. A method for producing a polyacetal copolymer. 9. The polyacetal according to claim 1, wherein the crude polymer after copolymerization is subjected to a catalyst deactivation treatment in a pulverized state containing at least 90% or more of a particle size of 3 mm or less. A method for producing a copolymer. 10. The method for producing a polyacetal copolymer according to claim 1, wherein the heat melting treatment is performed in the presence of a stabilizer.