JPH10182772A - Production of polyacetal polymer or copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject (co)polymer of a high quality in a high yield by (co)polymerizing trioxane using a rare earth meal salt of perfluroalkylsulfonic acid as a polymerization catalyst. SOLUTION: A rare earth metal salt (preferably Sc, Y, La, Pr or Nd) of a perfluoroalkylsulfonic acid (preferably trifluromethanesulfonic acid) is used as a (co)polymerization catalyst is used as a catalyst to polymerize trioxane or a mixture thereof (as a main component) with a comonomer copolymerizable therewith (preferably 1,3-dioxolane, diethylene glycol formal) to give the objective polyacetal polymer or copolymer. According to this process, a very high polymerization yield are attained with an extremely reduced amount of catalyst and a polymer of high molecular weight useful as a tough molding material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyacetal polymer or copolymer (these are collectively referred to as a (co) polymer). Specifically, in the (co) polymerization of trioxane as a main monomer and, in some cases, a co-monomer that can be copolymerized therewith, a rare earth metal salt of perfluoroalkylsulfonic acid is used as a novel polymerization catalyst. The present invention relates to a method for producing a polyacetal copolymer excellent in quality such as thermal stability and the like.

[0002]

2. Description of the Related Art Heretofore, as a method for producing a polyatasole (co) polymer, a cationic (co) polymer using trioxane as a main monomer and optionally a cyclic ether or cyclic formal having at least one adjacent carbon-carbon bond as a comonomer has been used. Known as cationic polymerization catalysts used for these (co) polymerizations are Lewis acids, especially boron,
Tin, titanium, phosphorus, arsenic and antimony halides, such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride and antimony pentafluoride, and complexes thereof Compounds such as compounds or salts, protic acids such as perfluoroalkylsulfonic acid, perchloric acid, esters of protic acids, anhydrides, or ion pair catalysts such as trimethyloxonium hexafluorophosphate, triphenylmethylhexafluoroarsenate Acetylhexafluorophosphate and acetylhexafluoroarsenate are known. Further, heteropoly acids, isopoly acids and their acid salts have also been proposed. Among them, boron trifluoride,
Alternatively, a coordination compound of boron trifluoride and an organic compound such as an ether is the most common as a (co) polymerization catalyst using trioxane as a main monomer, and is widely used industrially. However, in general, a crude (co) polymer obtained by using a known catalyst as described above has a limit in polymerization yield, degree of polymerization, and the like because polymerization reaction and decomposition reaction occur in competition with each other. However, since it has a large amount of thermally unstable portion at the molecular end, in order to put it to practical use, the unstable portion must be removed and stabilized. For this reason,
It requires a complicated post-processing step, consumes a large amount of energy for the processing, and is not economically advantageous. If the crude copolymer directly obtained by the polymerization reaction has few unstable parts, the stability of the final product will be excellent, and there will be advantages such as simplification of the post-treatment step. A method for obtaining a crude copolymer having a small number of stable parts has been desired.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention requires a high polymerization yield and a high molecular weight (co)
A polymer is obtained. Particularly, in the case of a copolymer, a high-quality crude polyacetal polymer having few unstable parts is obtained, and a thermally-stable polyacetal copolymer is produced by a simple process.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies on the type of polymerization catalyst to achieve the above object, and as a result, trioxane polymerization catalysts have not been known and their use has never been proposed. The present inventors have found that the use of a rare earth metal salt of perfluoroalkylsulfonic acid is extremely effective, and have completed the present invention. That is, the present invention relates to a process for producing a polyacetal (co) polymer by polymerization or copolymerization with trioxane or a comonomer having trioxane as a main monomer and a rare earth metal such as perfluoroalkylsulfonic acid as a polymerization catalyst. The present invention relates to a method for producing a polyacetal (co) polymer, wherein (co) polymerization is performed using a salt.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, a feature of the present invention resides in the use of a rare earth metal salt of perfluoroalkylsulfonic acid as a (co) polymerization catalyst. Specific examples of the perfluoroalkylsulfonic acid as an acid component constituting the catalyst include trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, and nonafluorobutanesulfonic acid. Among them, trifluoromethanesulfonic acid (triflate) is the most preferable in terms of polymerization activity. On the other hand, as is well known, the rare earth metal constituting the catalyst of the present invention is an element that is not filled with electrons of the f shell in terms of atomic structure, and is a so-called Sc (scandium), Y (yttrium) and atomic number 57 to 71. A generic term for lanthanoid elements, specifically Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm
(Samarium), Eu (eurobium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho
(Holmium), Er (erbium), Tm (thulium),
Yb (ytterbium), Lu (lutetium),
Among them, Sc, Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er,
It is preferably at least one selected from Yb and Lu. Such a rare earth metal salt catalyst of perfluoroalkylsulfonic acid of the present invention, the above-mentioned perfluoroalkylsulfonic acids, such as trifluoromethanesulfonic acid and the like,
It can be obtained by heat-treating rare earth metal oxides and hydroxides. This substance is used as Diel as a Lewis acid catalyst.
Although it is only known to be used for the s-Alder reaction, Friedel-Crafts reaction, etc., it has never been known as a catalyst for trioxane (co) polymerization, but according to the study of the present inventors, It has a very high polymerization activity as a (co) polymerization catalyst for a monomer mainly composed of trioxane, and therefore a (co) polymer having a high yield and a high degree of polymerization can be obtained in a very small amount. That is, a boron trifluoride-based catalyst which has been widely used in the conventional (co) polymerization of trioxane requires a catalyst amount of at least 3 × 10 ^-3 mol% with ^respect to all monomers, and a catalyst amount below this is extremely long for polymerization. Although it takes time and the final polymerization yield is low, according to the rare earth metal salt catalyst of perfluoroalkylsulfonic acid of the present invention, 2 × 10 ^-6 to 1 × 10 ^-4 mol% of all monomers is sufficient. A high yield can be obtained in a short period of time, and the characteristics of the catalyst itself and the use of a small amount are combined, so that the decomposition reaction is relatively low, so that a high degree of polymerization is obtained. A crude polymer is obtained, and in the (co) polymerization reaction of trioxane or the like with a conventional catalyst, the presence of trace impurities such as water is extremely harmful. However, according to the catalyst of the present invention, the presence of trace impurities such as water The adverse effects tend to be mitigated It is also advantageous in terms of the degree of purification of the monomer. The amount of the catalyst used in the (co) polymerization reaction of the present invention is not particularly limited, and an appropriate amount naturally varies depending on the polymerization temperature, time, monomer purity, catalyst type, and the like.
X 10 ^{-6 to} 5 x 10 ^-3 mol%, preferably 2 x
10 ^{-6 to} 3 × 10 ^-4 mol%, and as described above, 2 × 10 ^-6 to
1 × 10 ⁻⁴ mol% is possible and preferable. The catalyst is desirably added to the monomer by diluting it with a solvent that does not adversely affect the polymerization in order to uniformly conduct the reaction. Examples of the diluent include ethers such as di-n-butyl ether and 1,4.
Polar solvents such as dioxane, diglyme, esters such as butyl acetate, alkyl halides such as dichloromethane, dichloroethane and the like are suitable, but not limited thereto, and in the case of copolymerization, a part or all of the comonomer may be used. A method of adding a solution previously dissolved in a comonomer to trioxane, which is also used as a catalyst diluent, is also a preferable addition method, but in this case, the temperature is kept as low as possible until just before the addition so that polymerization of the comonomer itself does not occur before addition. Or, it is desirable to add to trioxane immediately after dilution.

The raw material monomer to be subjected to the (co) polymerization of the present invention is mainly composed of trioxane which is a cyclic trimer of formaldehyde. When trioxane is used alone, a homopolymer is obtained. Co-polymers are obtained by using possible comonomers. As the comonomer, any known comonomer having at least one adjacent carbon-carbon bond used for copolymerization with trioxane can be used. For example, cyclic formals or cyclic ethers such as 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, and epichlorohydrin are exemplified. Further, a vinyl compound such as styrene or a cyclic ester such as β-propiolactone may be used. Further, as a comonomer for the copolymer to form a branched or cross-linked molecular structure, a compound having two or more cyclic ether groups or cyclic formal groups such as alkylene-diglycidyl ether or diformal,
For example, butanediol diglycidyl ether, butanediol dimethylidene glyceryl ether and the like can be used. At least one such comonomer may be used, or two or more may be used in combination depending on the purpose. In particular, as the comonomer, cyclic formal or cyclic ether such as 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, and ethylene oxide is preferable. The amount of the comonomer used in the present invention is 20 mol% or less, preferably 0.2 to 10 mol%, based on trioxane. The larger the amount of the comonomer, the more advantageous the thermal stability of the produced polymer. However, if the amount of the comonomer is too large, the produced copolymer becomes soft and the melting point is lowered.

In the polymerization method of the present invention, a known chain transfer agent for adjusting the degree of polymerization, such as a low molecular weight linear acetal such as methylal, may be added according to the purpose. Further, a sterically hindered phenolic antioxidant may be present in an amount that does not affect the polymerization. Further, the polymerization system (monomer and the like) does not go beyond the absence of impurities having active hydrogen such as formic acid and water, but the adverse effect of the presence of water and the like is lower than that of the conventional catalyst as described above. It has the feature of being reduced and may also ease the purification of monomers from an economic point of view.

[0008] The polymerization method of the present invention can be carried out by the same equipment and method as the conventionally known polymerization or copolymerization of trioxane. That is, both batch type and continuous type are possible,
It is economical and common to use a liquid monomer to obtain a polymer in the form of a solid powder as the polymerization proceeds. 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 continuous extrusion mixer,
A twin-screw paddle-type continuous mixer, a continuous polymerization device such as trioxane proposed so far, and the like can be used, and two or more types of polymerization machines can be used in combination. The polymerization temperature is not particularly limited depending on the polymerization method, the type and amount of the catalyst used, etc., but if a generally used bulk polymerization method is employed, the polymerization is carried out in a temperature range of 60 to 120 ° C, preferably 65 to 110 ° C. . The polymerization time is also related to the amount of the catalyst, the polymerization temperature, etc., and is not particularly limited.
Generally, a polymerization time of 0.5 to 100 minutes is selected, and especially 1 to 15 minutes.
Minutes is preferred.

The reaction product after completion of the (co) polymerization is then subjected to a catalyst deactivation treatment by adding a catalyst deactivator. As the deactivator, various basic compounds are effective as in the case of conventionally known cationic catalysts, such as ammonia, various amine compounds, or alkali or alkaline earth metal oxides, hydroxides, and organic compounds. An acid salt, an inorganic acid salt, a trivalent phosphorus compound and the like can be mentioned, and a combination of two or more of these is also a preferable method. Examples of the amine compound include primary, secondary, and tertiary aliphatic amines and aromatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, butylamine, dibutylamine, tributylamine, and alcohols corresponding thereto. Examples include amines (eg, triethanolamine), aniline, diphenylamine, heterocyclic amine, hindered amine (various piperidine derivatives), and the like. Further, as the alkali or alkaline earth metal compound, inorganic weak acid salts such as oxides, hydroxides, carbonates, bicarbonates, phosphates, borates and silicates of alkali metals or alkaline earth metals , Acetate, oxalate,
Formate, benzoate, terephthalate, isophthalate, phthalate, organic acid salts such as fatty acid salts, methoxide, ethoxide, n-butoxide, sec-butoxide,
Alkoxides such as tert-butoxide, phenoxides and the like are mentioned, and among them, hydroxides, carbonates and fatty acid salts are preferably used. Here, examples of the alkali metal or alkaline earth metal component include lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium and the like, and among them, lithium, sodium, potassium, magnesium and calcium are preferably used. Specifically, calcium hydroxide,
Particularly preferred are magnesium hydroxide, sodium carbonate, calcium acetate, calcium stearate, calcium hydroxystearate and the like.

As a method for deactivating the catalyst, it is of course possible to add a large amount of a solution containing the above deactivator to the reaction product, and the effects of the present invention can be exhibited, and a high polymerization yield and a high quality crude product can be obtained. Although a polymer can be obtained, by using the polymerization catalyst of the present invention, the conversion of the monomer is increased in a relatively short polymerization time, and therefore, the amount of the unreacted monomer is extremely small (for example, 5% by weight or less). The catalyst can be deactivated with a small amount of deactivator as described below without washing the produced crude polymer or collecting monomers, and the process can be directly shifted to the next stabilization treatment. That is, the deactivation treatment of the catalyst of the present invention is carried out by contacting the (co) polymerized product with a basic gas or by adding a small amount containing a basic compound (for example, 7% by weight or less, further 5% by weight or less based on the produced polymer). This is also achieved by adding and mixing the solution of (1).

When a gaseous deactivator is used, ammonia or amines having a relatively low boiling point are used as the deactivator, and these are diluted with a single gas or an inert gas such as nitrogen gas. Deactivation is carried out by contacting the resulting polymer with the resulting polymer. Further, it is preferable to add, as a quencher, a quencher solution obtained by dissolving or dispersing the above various basic compounds in a small amount of water or an organic solvent. In this case, the addition amount of the quenching agent solution is 0.3 to 7% by weight based on the produced crude polymer.
Preferably it is 0.5 to 5% by weight. Even in such a small amount, the catalyst can be sufficiently deactivated by being sufficiently stirred and mixed with the crude polymer in combination with the characteristics of the polymerization catalyst used in the present invention. In any case, the catalyst deactivation treatment is preferably carried out in such a manner that the coarse polymer is a fine powder, and for this purpose, it is preferable that the polymerization reactor has a function of sufficiently pulverizing the bulk polymer. The reactant may be separately pulverized using a pulverizer, and then a deactivator may be added. Further, pulverization and stirring may be performed simultaneously in the presence of the deactivator. The particle size of the crude polymer in the deactivation treatment is 3 mm at least 90% or more.
The particle size is preferably 2 mm or less, more preferably 1 mm or less. The deactivation temperature is 0 to 140 ° C, preferably 20 to 120 ° C.

The (co) polymer thus obtained is generally subjected to a further stabilization treatment. If the homopolymer is a homopolymer, the terminal is blocked by esterification, etherification, urethanization, etc.If it is a copolymer, it is heated and melted, or heated in an insoluble or soluble liquid medium, and unstable. Achieved by selectively disassembling and removing portions. In particular, in the case of a copolymer, stabilization can be extremely simplified since there are fewer unstable parts at the stage of completion of polymerization than in the conventional method, and the amount of residual monomer can be reduced (improvement of polymerization yield).
After the deactivation treatment, if necessary, a well-known stabilizer or the like may be added, and the mixture may be melt-processed by a vented extruder or the like to obtain a pelletized product.

[0013]

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. In addition, the measuring method in an Example and a comparative example is as follows. Polymerization yield: The product obtained after the polymerization reaction is washed with a deactivator solution, dried, and expressed in terms of% by weight based on the total monomers supplied of the (co) polymer. Melt index (MI): Shows the melt index (g / 10 min) 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. (However, in order to prevent decomposition during measurement, add a certain stabilizer (Ciba Geigy, Irganox 1010 (1%) and melamine (0.1%)), mix well, and measure. Abundance of part): copolymer 1
g in a 50% aqueous methanol solution containing 0.5% ammonia 1
After heating at 180 ° C for 45 minutes in a closed container,
The amount of formaldehyde decomposed and eluted in the liquid is quantitatively analyzed, and is shown in terms of% by weight based on the copolymer. Heating weight loss rate The weight loss rate (% by weight) when 5 g of the copolymer is well mixed with a predetermined stabilizer powder (same as above) and heated in air at 220 ° C. for 45 minutes is shown.

Examples 1 to 10 and Comparative Examples 1 to 3 A predetermined amount of trioxane (water content: 30 ppm) was put into a jacket through which a heat medium can pass, and into a closed autoclave having a stirring, mixing and pulverizing function. After maintaining the internal temperature at about 70 ° C. through hot water of 70 ° C., the catalyst shown in Table 1 was added as a solution dissolved in butyl acetate, and the polymerization was started at the catalyst concentration (to the monomer) shown in Table 1. Five minutes later, a 0.1% aqueous solution of tributylamine was added to the autoclave twice as much as the total amount of the monomers, and the mixed solution was taken out and further pulverized to 100 mesh or less to stop the reaction.
Next, dehydration and acetone washing were performed, and after drying, the polymerization yield and MI were measured. Table 1 shows the results. For comparison, polymerization and evaluation were similarly performed for a case where boron trifluoride dibutyl etherate and trifluoromethanesulfonic acid were used as the catalyst. The results are shown in Table 1.

Examples 11 to 19 and Comparative Examples 4 and 5 Copolymerization was carried out at the same temperature using the same reactor as described above. However, 600 ppm of methylal as a chain transfer agent was previously dissolved and mixed in trioxane, and the catalyst was dissolved in the comonomer shown in Table 2 at 0 ° C. in advance and this comonomer was added to trioxane (the amount of catalyst is shown in Table 2). The polymerization was started.

After 5 minutes, 0.1% of triethylamine is added.
The reaction was stopped by adding an aqueous solution of a deactivator containing the same, and the same treatment was carried out as described above, and the polymerization yield, MI, alkali decomposition rate, and heating weight loss rate were measured. Table 2 shows the experimental conditions and the results. still,
For comparison, the same procedure was performed for boron trifluoride etherate and trifluoromethanesulfonic acid as catalysts.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

As is clear from the above description and Examples, the method using the catalyst of the present invention in the production of an acetal polymer or a copolymer is much more effective than the conventional method. A high polymerization yield can be obtained with a low amount of catalyst used, and the obtained polymer has a high molecular weight, which is suitable as a tough molding material. Further, in the case of a copolymer, a polymer having a particularly small number of unstable parts is obtained, and not only a product having excellent stability of a final product after a post-process is obtained, but also a post-treatment stabilization process is simplified. It is possible and economically advantageous.

Claims (5)

[Claims] 1. A rare-earth metal salt of perfluoroalkylsulfonic acid as a polymerization catalyst for producing a polyacetal (co) polymer by polymerization or copolymerization of trioxane or trioxane as a main monomer and a comonomer copolymerizable therewith. A method for producing a polyacetal (co) polymer, comprising conducting (co) polymerization using 2. The method for producing a polyacetal (co) polymer according to claim 1, wherein the rare earth metal salt of perfluoroalkylsulfonic acid as the catalyst is a rare earth metal salt of trifluoromethanesulfonic acid (triflate). 3. The catalyst according to claim 1, wherein the rare earth metal constituting the catalyst is Sc, Y,
The method for producing a polyacetal (co) polymer according to claim 1 or 2, wherein the polyacetal (co) polymer is at least one selected from La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu. 4. The method for producing a polyacetal copolymer according to claim 1, wherein the comonomer is a cyclic ether or cyclic formal having at least one carbon-carbon bond. 5. The polyacetal according to claim 1, wherein the comonomer is at least one compound selected from 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, and ethylene oxide. A method for producing a copolymer.