JP3181535B2 - 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. In detail, in the copolymerization with trioxane as a main monomer and a comonomer that can be copolymerized therewith, unreacted monomers can be efficiently and economically removed from the polymerization system at the latter or final stage of polymerization, recovered and reused. The present invention relates to a method for economically producing a polyacetal copolymer having excellent quality such as thermal stability in a simple process.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a polyacetal copolymer, cationic polymerization using trioxane as a main monomer and a cyclic ether or cyclic formal having adjacent carbon atoms as a comonomer has been known. Active catalysts include Lewis acids, especially boron, tin, titanium, phosphorus, arsenic and antimony halides, such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, pentafluoride. Compounds such as arsenic arsenide and antimony pentafluoride, and complex compounds or salts thereof, or protonic acids such as perfluoroalkylsulfonic acid (trifluoromethanesulfonic acid and the like), perchloric acid, esters and anhydrides of these protonic acids, and
Heteropoly acids (phosphomolybdic acid, phosphotungstic acid, silicomolybdic acid, silicotungstic acid, etc.), isopolyacids and their acid salts have also been proposed. Also, ion pair catalysts such as trimethyloxonium hexafluorophosphate, triphenylmethylhexafluoroarsenate, acetylhexafluorophosphate and acetylhexafluoroarsenate are known. Among them, boron trifluoride or a coordination compound of boron trifluoride and an organic compound such as ethers is the most common as a (co) polymerization catalyst using trioxane as a main monomer, and is widely used industrially. ing.

However, using any of the catalysts, the polymerization rate is rapidly reduced in the latter stage of the polymerization, and it is extremely difficult to obtain a polymerization yield close to 100% in a short time, and it takes an extremely long time to be inefficient. Not only that, in the late stage of polymerization, the action of the catalyst to promote the decomposition of the produced polymer becomes relatively dominant, which not only reduces the molecular weight, but also increases the unstable part and increases the quality such as thermal stability. Is also inferior. In addition, if the amount of the polymerization catalyst is increased, the polymerization rate is accelerated as a whole, but the quality of the resulting crude polymer is further deteriorated, and a complicated stabilization treatment is required in the post-process, so that the entire production process is never a preferable method. Absent.

Therefore, in the conventional method for producing a polyacetal copolymer, the polymerization is stopped by adding a relatively large amount of a solution containing a catalyst deactivator at a stage where the conversion is relatively low, and at the same time, the remaining unreacted monomer is removed. The method of washing and recovering, purifying and reusing is generally used.However, since the unreacted monomer washed and recovered by such a method is recovered as a relatively low-concentration solution, it is necessary to reuse it. Separation and purification require complicated steps and energy, and if recovery of the unreacted monomer is abandoned, complete loss will result, which is not economically preferable.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is capable of obtaining a high-quality crude polymer and economically producing a thermally stable polyacetal copolymer by a simple process. It is an object of the present invention to allow the unreacted monomer to be economically recovered and reused, and to achieve both the quality of the produced polyacetal polymer and the economic effect. That is, in the copolymerization using trioxane as a main monomer, the present inventors have found that the polymerization rate is remarkably reduced at the latter or final stage of the polymerization, and it takes not only a very long time to obtain a polymerization yield close to 100% but also a very long time. In view of the fact that the decomposition reaction becomes relatively predominant in the late stage of polymerization, the molecular weight is reduced, the amount of unstable polymer is significantly increased, and quality problems such as complicated stabilization treatment are required.
Before the completion of the polymerization reaction, trioxane and other unreacted monomers are vaporized when a certain degree of polymerization is reached, separated and removed from the polymerization system, and recovered. Compared to the method of collecting as a monomer solution having a high concentration, the separation and collection can be performed economically, and can be reused as it is or only by a very simple purification treatment, and the weight due to remarkable decomposition at the end of the polymerization reaction can be reduced. It is possible to easily and economically recover and reuse the unreacted monomer while avoiding deterioration of the coalescence quality,
Both quality and economic effects were expected. However, the present inventors have conducted various experiments and studies based on such a concept, and found that when unreacted monomers are vaporized in the late stage of polymerization,
It has been found that a polymerization reaction occurs in a line for vaporizing and collecting unreacted monomers, which hinders stable and smooth vaporization and collection of unreacted monomers for a long period of time. This tendency is particularly remarkable when a volatile polymerization catalyst such as boron trifluoride is used, and such a volatile catalyst causes polymerization in the recovery system, with a part of the volatile catalyst accompanying the monomer separated by vaporization. It is understood that. The present invention solves the above-mentioned problems in the case of vaporizing, separating, and recovering unreacted monomer in the latter or final stage of polymerization, smoothly vaporizing the unreacted monomer, separating and collecting the unreacted monomer from the polymerization system, and obtaining a high-quality polyacetal copolymer. The purpose is to produce a polymer economically.

[0006]

Means for Solving the Problems The present inventors have solved the above-mentioned problems, particularly, the problem of the formation of a polymer in a recovery system in the case of vaporizing, separating and recovering unreacted monomers in the latter or later stages of polymerization. As a result of studying to stably vaporize and collect the unreacted monomer, the unreacted monomer separated by adding a specific amount of basic substance and co-existing with the unreacted monomer vaporized and separated was treated. The production of polymer in the recovery system is suppressed, the unreacted monomer can be separated and recovered smoothly, and can be reused, enabling the production of economically good-quality polyacetal copolymer. . That is, the present invention uses trioxane as a main monomer, uses a cyclic ether or cyclic formal having at least one carbon-carbon bond as a comonomer, and copolymerizes with a cationic active catalyst to produce a polyacetal copolymer. At least 60% by weight (based on total monomers), unreacted monomers are vaporized and separated, removed, and recovered from the polymerization system. Upon recovery, a basic compound is added to and coexisted with the unreacted monomers. A method for producing a polyacetal copolymer characterized by the following:

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, the raw material monomer to be copolymerized in the present invention is mainly composed of trioxane, which is a cyclic trimer of formaldehyde, and the comonomer is at least one adjacent carbon atom used for copolymerization with conventional trioxane. Any known cyclic formal or cyclic ether having a bond can be used. Such comonomers include, for example, 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal,
Examples include cyclic formals such as 1,3-dioxane and 1,3,5-trioxepane, and cyclic ethers such as ethylene oxide, propylene oxide, and epichlorohydrin. Compounds having two or more cyclic ether groups or cyclic formal groups such as alkylene-diglycidyl ether or diformal as comonomers for the copolymer to form a branched or cross-linked molecular structure, for example, butanediol diamine Glycidyl ether, butanediol dimethylidene glyceryl ether and the like can also be used. Such comonomers may be used in combination of at least one kind or two or more kinds depending on the purpose. Particularly, as the comonomer, a cyclic formal such as 1,3-dioxolan, diethylene glycol formal, 1,4-butanediol formal, ethylene oxide or a cyclic ether is preferable. The amount of the comonomer used in the present invention is 0.1 to 20 mol%, preferably 0.2 to 10 mol%, based on trioxane.
Mol%. 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, which is not preferable.

In the copolymerization 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. . It is also a preferable polymerization method that a sterically hindered phenolic antioxidant that does not affect the polymerization is previously added to the monomer or comonomer and copolymerized in the presence thereof. Further, it is preferable that impurities having active hydrogen, such as formic acid, water, and methanol, are not substantially present in the polymerization system (monomer or the like). For example, these impurities are preferably 20 ppm or less, and more preferably 10 ppm or less. desirable.

Next, as the polymerization catalyst in the present invention,
Any of the general cation-active catalysts exemplified above may be used. Above all, boron trifluoride (gas) which is a volatile polymerization catalyst, a coordination compound of boron trifluoride and an organic compound (for example, ethers), or perchloric acid or perfluoroalkylsulfonic acid (for example, trifluoromethanesulfonic acid) , Pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, etc., or their anhydrides, alkyl esters, etc., are volatile catalysts which are particularly suitable for obtaining the effects of the present invention. The method of adding the catalyst is not particularly limited, and may be added to a mixture of trioxane and a comonomer.However, it is added and mixed in a comonomer in advance at a relatively low temperature, and before the polymerization of the comonomer itself proceeds. The copolymerization may be started by mixing with trioxane.

The polymerization method of the present invention can be carried out with the same equipment and method as the conventionally known polymerization method of trioxane. That is, any of a batch type and a continuous type is possible, and a continuous bulk polymerization method using a liquid monomer and obtaining a solid powder bulk polymer with the progress of polymerization is industrially common and preferred. In this case, if necessary, a small amount of an inert liquid medium may coexist. As a polymerization apparatus used in the present invention, a batch-type reactor with a temperature-controllable stirrer generally used can be used. As a continuous type, a co-kneader, a twin-screw continuous extrusion mixer, a twin-screw paddle can be used. A continuous polymerization device of a type such as a continuous mixer and other conventionally proposed trioxane and the like can be used, and two or more types of polymerization devices can be used in combination. Particularly, those having a crushing function such that a solid polymer produced by a polymerization reaction can be obtained in a fine form are preferable. The polymerization temperature is not particularly limited by the type of polymerization, the type of catalyst used, the amount, and the like.However, 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. . Further, the polymerization time is also related to the amount of the catalyst, the polymerization temperature, and the like, and is not particularly limited.
A polymerization time of 00 minutes is selected, and particularly preferably 1 to 30 minutes.

According to the present invention, the unreacted monomer is vaporized and separated from the polymerization system at an appropriate late or final stage of the polymerization in which the rate of the polymerization reaction by the above method is reduced and the decomposition reaction becomes relatively dominant. It is characterized by being removed. Separation by vaporization of such unreacted monomers has a conversion of at least 60
% (Based on total monomers), preferably 70-90%, particularly preferably 75-85%. When the unreacted monomer is separated at a stage where the polymerization rate is too low, the quality is good, but the vaporization, separation, and recovery require a long time, and the yield of the obtained polymer is reduced, which is not economically preferable. . Separation of the unreacted monomer at the stage when the polymerization rate becomes excessive can be performed in a short time and the yield is high, but it takes a long time for the polymerization, and the decomposition takes place in the later stage. A reaction occurs and is not preferable in quality. From this point of view, the present invention suitably performs the separation of the unreacted monomer when the above-mentioned polymerization rate is reached, and within this range, it may be appropriately selected according to the purpose.

In order to efficiently vaporize and separate the unreacted monomer in a short time, the polymer should be fine particles (at least 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less).
The polymer is preferably pulverized once through a pulverizer or, at the same time as the pulverization, to vaporize and separate the unreacted monomer. As described above, the present invention is characterized in that the unreacted monomer is vaporized and separated and removed from the reaction system, and the monomer mainly composed of trioxane in the present invention has a high volatility, so that it is slightly polymerized at a polymerization temperature or at a predetermined stage. It is possible to remove the reaction system from the reaction system by evaporating the reaction system under reduced pressure by raising the temperature, or by passing an inert carrier gas such as nitrogen gas, or by using both together in a surprisingly simple manner. .

Next, the present invention provides at least the separated unreacted monomer in order to prevent the obstruction of the recovery line due to the formation of a polymer from the separated monomer in the vaporization, separation and recovery of the unreacted monomer. The second feature of the reactive monomer is that a predetermined amount of a basic substance is added and made to coexist, and thus the unreacted monomer is vaporized,
Separation and recovery can be performed stably and smoothly. Because the unreacted monomer is separated as a gas as a basic compound added to the unreacted monomer for coexistence for this purpose,
Volatile substances are preferred, for example ammonia and aliphatic amine compounds, such as methylamine, dimethylamine,
Trimethylamine, ethylamine, diethylamine, triethylamine, butylamine, dibutylamine, tributylamine and the corresponding alcohol amines, and the like.Examples include any basic substance as long as it has volatility at the treatment temperature and pressure. Even with a relatively high boiling point, the purpose can be achieved by diluting with a carrier gas or the like and allowing it to coexist. Such a basic substance may be added to the unreacted monomer in a gaseous state as it is, or may be added as a solution of an inert solvent and vaporized together with the unreacted monomer to coexist. In addition, even if the unreacted monomer is vaporized and separated for the purpose of deactivating the polymerization catalyst and adding a deactivator for terminating the polymerization, a basic substance as a deactivator accompanies the vaporized and separated monomer in the present invention. The goal of is achieved.

According to the method of the present invention, unreacted monomers are gasified and separated from the polymerization reaction system, and are not washed (extracted) and separated by a solvent or the like. Since only a very small amount of a basic substance (for example, 0.1 to 30 mol% of the amount of the used polymerization catalyst) coexists to prevent polymerization at the time of the above-mentioned recovery is sufficient, it is mixed with a new monomer and reused as it is. However, it can be used with almost no adverse effect on the polymerization reaction. Also, even if a relatively large amount of a basic substance or other contaminants directly hinders direct reuse, the energy required for the recovery and purification of the trioxane is greatly reduced by combining it with a new trioxane purification process. be able to. Therefore, compared with the conventional case of separation and collection as a low-concentration solution by washing, concentration, purification, and the like can be avoided, which is complicated and requires a large amount of energy to recover and purify. It has the advantage that it can be recovered and reused.

In the present invention, the unreacted monomer is separated and removed from the polymerization system by the above-mentioned method, and at least the residual unreacted monomer of the polymerization system is at most 5% by weight, preferably at most 2% by weight, more preferably at most 2% by weight, based on the polymer. Is performed until it becomes 1% by weight or less. Naturally, it is preferable that the amount of the final residual monomer is small because it is lost as it is.However, it takes a long time to eliminate the residual monomer, which is uneconomical, and the decomposition of the polymer also occurs. It is not necessary to round up at an appropriate place in the above range.

The polymer obtained by vaporizing and separating and removing the unreacted monomer may be further deactivated by adding a similar basic substance or a substance known as a deactivator for another catalyst, if necessary. After sufficient treatment, or by adding a basic substance as a catalyst deactivator and performing a sufficient deactivation treatment, unreacted monomers are vaporized and separated and removed, and a part of the basic substance as a deactivator After the unreacted monomer is vaporized and removed, various known stabilizers and the like are added as it is, and if necessary, a small amount of water and other stabilizing accelerators are added. It can be melt-kneaded, extruded and stabilized to form a final product (pellet). In the present invention, since a large amount of the deactivator solution is not used and the unreacted monomer is almost completely removed, the product can be produced by the simple post-treatment as described above, and the production process is very economical. And the quality is good.

The method of the present invention only needs to satisfy the above-mentioned basic constitutional requirements, and specific embodiments thereof can be carried out in the following various modes. For example, (I) using a continuous polymerization apparatus, conditions are set so that a predetermined polymerization rate is obtained at the outlet, and a decompression, suction, or a flow mechanism of an inert gas stream is provided at or near the outlet. In vaporizing and separating the unreacted monomer, (a) a volatile basic substance is introduced into the vaporization outlet of the unreacted monomer, and a minimum amount of a basic gas is added and mixed to recover (b) volatilization to the polymer Add the required minimum amount of the basic substance, vaporize it with the unreacted monomer, and make the necessary amount coexist with the unreacted monomer that has been vaporized and separated. (C) Mix a predetermined amount of the basic substance into the inert gas stream According to the above method, the amount of the basic gas added and mixed in the vaporized and separated unreacted monomer is extremely small (this may be determined as appropriate in preliminary experiments). Good, generally heavy 0.1 for the catalyst
30 mol% is sufficient), the recovered monomer can be mixed with a new monomer and reused for polymerization as it is.However, after the unreacted monomer is separated, the polymerization system is sufficiently deactivated with a catalyst. It is preferable that the same or different quenching agents be additionally treated to completely deactivate. (II) The polymerizer effluent is pulverized sufficiently, transferred to another deactivator treatment device, and a volatile or gaseous basic substance is added to deactivate the catalyst and simultaneously vaporize and separate unreacted monomers. Part of the basic substance is entrained in the separated monomer. (III) In (II), the addition of the basic substance is divided into two stages,
Initially, a minimum amount is added to vaporize and remove the unreacted monomer, and after separation, additional treatment is performed to perform sufficient deactivation treatment (at this time, the treatment device may be divided into two stages. ).
According to this method, the content of the basic substance in the recovered monomer is minimized, and the recovered monomer can be reused as it is. In the embodiments (II) and (III), continuous processing is possible and efficiency is improved by using a vertical or horizontal apparatus to make the flow of the carrier gas (including the vaporized monomer) and the polymer flow countercurrent. It should be noted that the above-described exemplary embodiments can employ other modified modes by combining and using a part of each of them, and may be appropriately selected and implemented.

[0018]

As is clear from the above description and the examples, according to the manufacturing method of the present invention, compared with the conventional method,
Easily separate and recover unreacted monomers with simple processes.
The polyacetal copolymer which can be reused and has excellent quality such as thermal stability can be economically produced.

[0019]

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 parts are expressed by weight unless otherwise specified. -Polymerization rate or polymerization yield: after the polymerization reaction or after the unreacted monomer recovery obtained product is washed with a deactivator solution, and dried,
It is shown as a percentage of the total monomer fed to the polymer. -Residual monomer content: The product obtained after collecting the unreacted monomer is washed with a predetermined deactivator solution, and the monomer in the washing liquid is determined by gas chromatography and is shown as% of the crude polymer. Melt index (MI): Shows a melt index (g / 10 min) measured at 190 ° C. for a crude polymer (powder or granule) or an extruded pellet. This was evaluated as a characteristic value for 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 (0.5%) and melamine (0.1%) and mix well. Abundance): 1 g of the crude polymer powder was placed in 100 ml of a 50% aqueous methanol solution containing 0.5% ammonia, heated at 180 ° C. for 45 minutes in a closed vessel, and the amount of formaldehyde decomposed and eluted in the liquid was quantitatively analyzed. Heating weight loss rate: 5 g of a copolymer pellet extruded by melt extrusion (mixed with the same stabilizer as described above) was placed in air at 230 ° C and 45 ° C.
It shows the weight loss rate when heated for one minute.

Examples 1-3 and Comparative Examples 1-2 Trioxane containing 3.5% 1,3-dioxolane as a comonomer in a kneader equipped with a jacket through which a heat medium can pass and a stirring blade having a mixing and grinding function. Into the jacket, keep the internal temperature at about 70 ° C by passing warm water through the jacket at 70 ° C, and then use a solution of boron trifluoride in dibutyl ether (40% as boron trifluoride with respect to all monomers).
ppm) was added to perform polymerization. Then, the polymerization rate is about 75
% (From a preliminary experiment under the same conditions), when the temperature reached about 105 ° C., the nitrogen gas containing a basic gas shown in Table 1 was passed through the exhaust hole (jacketed, 120 ° C.) provided at the upper part of the apparatus while passing nitrogen gas. The unreacted monomer is vaporized by suction under reduced pressure for one minute and separated and removed from the reaction system.
The mixture was cooled to ℃ and condensed and collected. In the collected monomers and in the collecting equipment, almost no polymer was formed, and the polymer was collected smoothly. The polymerization system after the unreacted monomer was vaporized and separated was further added with an aqueous solution of triethylamine, mixed well, thoroughly deactivated and washed at the same time, and the residual monomer amount and polymerization yield were measured and obtained. The amount of the unstable part (alkali decomposition rate) of the copolymer powder was measured. Table 1 shows the results. On the other hand, for comparison, the same experiment was performed for the case where the basic gas was not added and the basic gas was not included in the vaporized unreacted monomer, and the vaporization and separation of the monomer were attempted. A polymer was formed and unreacted monomers could not be collected smoothly (Comparative Example 1). For comparison, the polymerization reaction was continued for a long time to carry out the polymerization until the polymerization rate reached about 96%, and then the catalyst was subjected to a deactivation cleaning treatment. The results are shown in Table 1 (Comparative Example 2).

[0021]

[Table 1]

Examples 4 to 6 A similar polymerization experiment was conducted by mixing the monomers recovered in Examples 1 to 3 with a new monomer. As a result, a slight decrease in the polymerization rate and an increase in MI were observed. There was hardly any trouble in the polymerization behavior and the properties of the polymer.

Examples 7 to 9 and Comparative Example 3 A barrel having a jacket in which two circles partially overlap each other and through which a heating medium is passed, and a number of paddles for stirring and propulsion inside the barrel. Using a continuous mixing reactor provided with two 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 3.0% of dioxolane and 700 ppm of methylal as a molecular weight regulator was continuously supplied, and boron trifluoride was continuously added so as to be 40 ppm with respect to all monomers to carry out copolymerization. Then, the reaction product discharged from the polymerization machine discharge port (the intermediate polymerization rate is about 80%) is passed through a pulverizer so that the average particle size becomes 1 mm or less, and the mixture is fed into a second continuous mixing device (jacket at 100 ° C.). While stirring and mixing at one end of
It is moved in the direction of the outlet, while nitrogen containing a predetermined amount of the basic gas shown in Table 2 is introduced from the direction of the outlet, and is brought into contact with the polymer in the opposite direction (countercurrent) to the movement of the polymer. During this time, the unreacted monomer is vaporized, and is separated and removed together with the basic gas-containing nitrogen gas by suction under reduced pressure from the exhaust pipe (120 ° C.) of the second device.
And condensed and collected. The collection could be carried out smoothly, and almost no polymer was found in the collection equipment and the collected monomers, and a long-time continuous operation could be stably performed. Next, the polymer discharged from the second device was measured for the amount of residual unreacted monomer and the polymerization yield. When the amount of the basic gas supplied to the second device was small (Example 7,
8) In addition, after the same basic gas is additionally treated to the discharge to deactivate the catalyst sufficiently, and the basic substance added in the second device is excessive, the deactivation treatment of the catalyst is sufficient. In such a case (Example 9), a stabilizer (same as above) was added as it was, and the mixture was melt-kneaded with a vented extruder, extruded to remove unstable portions, and stabilized to produce pellets. The MI and the weight loss rate of the pellets were measured. Table 2 shows the results.
For comparison, vaporization, separation, and collection of unreacted monomer were similarly attempted without introducing a basic substance into the second apparatus, but a polymer was gradually generated and adhered to the collector, and was trapped. The collecting line was blocked, and it was finally impossible to stably collect (Comparative Example 3).

[0024]

[Table 2]

Examples 10 to 11, Comparative Example 4 Using the same continuous polymerization apparatus as in Examples 7, 9 and Comparative Example 3,
The same continuous polymerization was performed except that trifluoromethanesulfonic acid (1 ppm based on all monomers) was used as a catalyst.
Next, the reaction product (polymerization rate: about 82%) discharged from the polymerization machine discharge port was pulverized in the same manner as in Examples 7 and 9 and Comparative Example 3, and treated in the same manner in the second apparatus to obtain unreacted monomer. Was vaporized, separated and recovered. As a result, when a basic gas was added and coexisted for vaporization, separation, and recovery of unreacted monomers (Examples 10 and 11), production and adhesion of a polymer were not observed for a long time, and the recovery operation was stably performed. Was able to do,
In the case where no basic gas was added and coexisted (Comparative Example 4), generation and adhesion of a polymer were observed in the recovery system, and trouble was observed in long-term stable operation. After the unreacted monomer was separated, the catalyst was further deactivated in the same manner as in Examples 7 and 9 (Example 10), or as it was (Example 11). , And extruded to form pellets, which were evaluated in the same manner. Table 3 shows the results.

[0026]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (56) References US Patent 5,512,284 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 2/00-2/38

Claims (13)

(57) [Claims] Claims: 1. A method for producing a polyacetal copolymer by using trioxane as a main monomer and using a cyclic ether or cyclic formal having at least one carbon-carbon bond as a comonomer and copolymerizing with a cationically active catalyst to produce a polyacetal copolymer. At the stage when the content becomes 60% by weight (based on all monomers), unreacted monomers are vaporized and separated, removed, and recovered from the polymerization system. In the recovery, it is necessary to add a basic compound to the unreacted monomers and make them coexist. A method for producing a characteristic polyacetal copolymer. 2. The method for producing a polyacetal copolymer according to claim 1, wherein the residual monomer after vaporizing, separating and removing the unreacted monomer is 5% by weight or less of the copolymer. 3. The method for producing a polyacetal copolymer according to claim 1, wherein the basic compound is a volatile basic substance. 4. The method for producing a polyacetal copolymer according to claim 1, wherein the basic compound is ammonia or an aliphatic amine. 5. The method for producing a polyacetal copolymer according to claim 1, wherein the polymerization catalyst is boron trifluoride or a coordination compound thereof. 6. The method for producing a polyacetal copolymer according to claim 1, wherein the polymerization catalyst is perfluoroalkylsulfonic acid, perchloric acid, or a derivative thereof. 7. A basic device or a diluent gas introduction mechanism, a reduced pressure suction or an inert gas flow mechanism is provided in the vicinity of the outlet of the continuous polymerization apparatus or in a second apparatus connected thereto. The reaction monomer is vaporized and removed, and upon recovery, a basic compound is added to the polymerization system or added to the vaporized and separated unreacted monomer to coexist with the vaporized and separated monomer. The method for producing a polyacetal copolymer according to any one of the above. 8. The polyacetal copolymer according to claim 1, wherein the amount of the basic compound in the unreacted monomer vaporized and separated is 0.1 to 30 mol% based on the amount of the catalyst used. Production method. 9. The polyacetal according to claim 1, wherein the polymerization reaction mixture is separated and recovered by pulverizing an unreacted monomer after pulverizing the polymerization reaction mixture to an average particle size of at least 2 mm or less, or while pulverizing. A method for producing a copolymer. 10. The process for producing a polyacetal copolymer according to claim 1, wherein the unreacted monomer vaporized, removed and recovered from the polymerization system is reused as a monomer for polymerization. 11. After the unreacted monomer is vaporized and separated and recovered by the method according to any one of claims 1 to 10, a catalyst deactivator is further added to the polymer to carry out a deactivation treatment of the polymerization catalyst. A method for producing a polyacetal copolymer. 12. A reaction product polymerized to at least 60% by weight or more (based on all monomers) in a polymerization apparatus is transferred to a second apparatus, and a basic substance is added thereto to deactivate a polymerization catalyst. At the same time, unreacted monomers are vaporized and separated,
The method for producing a polyacetal copolymer according to claim 1, wherein the polyacetal copolymer is recovered. 13. A polymer obtained by vaporizing and separating unreacted monomers according to the method of claim 11 or 12, and subjecting the polymer subjected to catalyst deactivation treatment to melt kneading and extrusion in a vented extruder in the presence of a stabilizer. A method for producing a characteristic polyacetal copolymer.