JPH03269009A - Production of acetal polymer or copolymer - Google Patents

Abstract

PURPOSE:To obtain a high-molecular weight acetal (co)polymer having excellent heat stability in subjecting a monomer such as formaldehyde to bulk (co) polymerization, by making a water content of monomer <=a specific amount and using a specific polymerization catalyst in a specific ratio. CONSTITUTION:In subjecting a monomer comprising formaldehyde, a cyclic oligomer or a cyclic acetal thereof or the monomer and a comonomer copolymerizable with the monomer to bulk (co)polymerization, the water content of the monomer is made <=100ppm, preferably <=10ppm, a compound (e.g. fluorosulfonic acid anhydride) shown by the formula (n is >=0) in a molar ratio to the monomer of 1X10<-8> to 5X10-<6>, preferably 1X10<-7> to 1X10<-6> is used as a catalyst, the monomer or the monomer and the (co)monomer are subjected to bulk (co)polymerization (preferably at 60-140 deg.C for 15 seconds to 20 minutes), the polymerization catalyst is neutralized, deactivated and stabilized to give an acetal (co)polymer with a small amount of the catalyst used and in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an acetal polymer or copolymer.

More specifically, formaldehyde or its cyclic t+)
-f-mer or cyclic acetal is used as a monomer, or one of these monomers is used as a raw monomer, and when copolymerizing with these raw monomers and performing bulk polymerization in the presence of a vine comonomer, the general formula (F (CF2 ) n502) 20(n-0
The molar ratio of the compound having the structure (an integer greater than or equal to
The present invention relates to a method for producing an acetal polymer or copolymer, which is used in the range of 10-' to 5 x 10-' and has a water content of 1100 pp (by weight) or less in all monomers.

[Prior Art and Problems to be Solved by the Invention] In the homopolymerization and copolymerization of formaldehyde or its cyclic oligomers, such as trioxane or tetraoxane, and the homopolymerization and copolymerization of cyclic acetals or ketals, such as 1,3-dioxolane, Cation-activated catalysts are used.

Examples of such catalysts include Lewis acids, especially halides of boron, tin, titanium, phosphorous, arsenic and antimony, such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorous pentachloride, trifluoride. Compounds such as phosphorus, arsenic trifluoride and antimony trifluoride, and their complexes or salts;
Protic acids, such as verchloric acid, esters of protic acids, such as verchloric acid-tertiary butyl ester, have been proposed. Among them, boron fluoride or coordination compounds of boron and organic compounds, such as coordination compounds with ethers, are the most common catalysts for homopolymerization of cyclic oligomers of formaldehyde such as trioxane, and copolymerization catalysts with cyclic oligomers as the main monomer. It is widely used in industry.

However, most of these catalysts are not sufficient in terms of polymerization activity, and a certain amount of catalyst is required to satisfy the polymerization yield, and post-treatments such as deactivation and washing are complicated. It also affects the thermal stability of the product.

As a highly active catalyst, perfluoroalkyl sulfonic acid disclosed in JP-A No. 48-29894 is known. However, when bulk polymerization is carried out, the catalyst must be diluted with a large amount of relatively expensive polar solvent in order to uniformly disperse the catalyst in the monomer, which has a considerable effect on the polymerization reaction.

Regarding the polymerization of trioxane using trifluoromethanesulfonic anhydride, Pencxek et al.
kulare Chemie 172.243-247
(1973)), but it is a solution to slurry polymerization in cyclohexane, and the polymerization yield is not very good despite using a large amount of catalyst.

Therefore, the present inventors solved the problems of the above-mentioned conventional technology,
As a result of research into a polymerization method that provides a high yield with the addition of a small amount and does not impair the quality of the product, the present invention was arrived at.

[Means and effects for solving the problems] That is, the present invention uses formaldehyde or its cyclic oligomer or cyclic acetal as a monomer, or one of these monomers as a raw monomer, and a comonomer that can be copolymerized with these raw monomers. For bulk polymerization in the presence of , a compound having the structure of the general formula (F(CF2).502) 20 (n = an integer of 0 or more) is used as a polymerization catalyst at a molar ratio of 1 x 10 to all monomers.
-' to 5 x 10-', and the water content in all monomers is 10011 p■ (weight base ts) or less. .

By using a compound having the above structure as a polymerization catalyst, it is possible to homopolymerize formaldehyde or its cyclic oligomer or cyclic acetal even in extremely small amounts, and to copolymerize one of these as a raw monomer with a vine comonomer. copolymerization can be carried out more easily than before, and it has become possible to obtain a high polymerization yield.

Specific examples of catalysts used by the method of the invention include, for example, fluorosulfonic anhydride, trifluoromethanesulfonic anhydride, pentafluoroethanesulfonic anhydride, heptafluoropropanesulfonic anhydride, nonafluorobutanesulfonic anhydride. These include anhydride, undecafluoropentanesulfonic anhydride, perfluoroheptanesulfonic anhydride, and the like.

The amount of the above-mentioned superstrong acid anhydride used as a polymerization catalyst varies depending on its type, and the polymerization reaction can be adjusted by appropriately changing the amount added. Ratio I x 10-I'' to 5 x 10-'
, preferably 1×10− to I×10−
'is. For example, for trifluoromethanesulfonic anhydride, an amount of I x 10-' to 5 x 10-' is sufficient. The ability to perform polymerization or copolymerization even with such a small amount of catalyst is effective in minimizing undesirable reactions such as decomposition of the main chain of the polymer and depolymerization caused by the catalyst, and is also economically advantageous. If it is less than @1 x 10-@, the polymerization yield will be low, and if it is more than 5 x 10-@, the thermal stability of the polymer will decrease, which is not preferable.

The above-mentioned superstrong acid anhydride used in the present invention is preferably diluted with an inert solvent that does not have an adverse effect on the polymerization of formaldehyde or its cyclic oligomer or cyclic acetal, and then added to the monomer in order to carry out the reaction uniformly. Although any solvent that does not participate in the organic polymerization process can be used as a solvent, the present catalyst is characterized by being very easily soluble in solvents such as non-polar aliphatic hydrocarbons, such as hexane and cyclohexane. This is a great advantage as other highly active catalysts generally require the use of large amounts of highly polar solvents. Further, it is not necessary to use a polar solvent such as ether which acts as a molecular weight regulator, which is advantageous in obtaining a high molecular weight polymer.

Raw monomers that are the object of the present invention include formaldehyde, cyclic oligomers thereof, such as trioxane as a trimer and tetraoxane as a tetramer, and compounds represented by the following general formula (1) -4 (in the formula R,,R,, R3 or R4 are the same or different and mean a hydrogen atom, an alkyl group, or a halogen-substituted methylene group or an oxymethylene group, and R3 is a methylene group or an oxymethylene group, or an alkyl group or a halogen group, respectively. methylene group or oxymethylene group substituted with an alkyl group (in this case, p represents an integer of O to 3) or the formula -(CH2) q-OCH2-
or -(OCHzGHz)-OCHz-2
It means a small group (in this case, p represents 1 and q represents an integer from 1 to 4). The alkyl group has 1 to 5 carbon atoms,
1 to 3 hydrogen atoms may be replaced by halogen atoms, especially chlorine atoms, for example epichlorohydrin, ethylene oxide, 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1.3
-dioxane, propylene oxide, etc.

In particular, trioxane is the most suitable representative monomer as the main monomer in the case of homopolymerization or copolymerization.

Although the method of the present invention is useful for the homopolymerization of formaldehyde or its cyclic oligomers or cyclic acetals, it is particularly useful for copolymerizing one of these as a raw monomer with other copolymerizable comonomers. In the case of copolymerization, it is effective not only in copolymerization with at least one comonomer that copolymerizes with the raw monomer, but also in multicomponent copolymerization of two or more types. This includes comonomers that produce polymers with branched or crosslinked molecules. The most common comonomer is exemplified by the compound represented by the above general formula (I).

Furthermore, cyclic esters such as .beta.-propiolactone and vinyl compounds such as styrene or acrylonitrile are also used. In addition, as a comonomer for forming a branched or linear molecular structure, alkyl-mono(or di)-glycidyl ether (or formal) such as methylglycidyl formal, ethylglycidyl formal,
Propyl glycidyl formal, butyl glycidyl formal, ethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether and bis(
1,2,6-hexandriol) triformal and the like. Among them, trioxane is the main monomer,
Ethylene oxide or 1,3-dioxolane, 1.4
In the case of copolymerization using a cyclic ether such as -butanediol formal or a cyclic formal as a comonomer, the effectiveness of the catalyst of the present invention is particularly exhibited.

The water content in the monomer or monomer mixture used in the present invention is 1100 pp or less, preferably 10 pp by weight.
pm or less. If it exceeds 1100 pp, it is not preferable because the polymerization rate is slow and the yield is low, or polymerization does not occur. In addition, in the polymerization method of the present invention, it is also possible to further use a known chain transfer agent, such as a low molecular weight linear acetal, in order to adjust the degree of polymerization depending on the purpose.

Bulk polymerization using the polymerization catalyst of the present invention can be carried out batchwise, continuously,
Either method is possible, and a common method is to use a monomer in a molten state and obtain a polymer in the form of solid powder as the polymerization progresses.

As the polymerization equipment used in the present invention, a generally used reaction species equipped with a stirrer can be used as a batch type, and as a continuous type, a co-kneader, a twin-screw continuous extrusion mixer, or a twin-screw paddle type continuous mixing machine can be used. A continuous polymerization device such as a machine can be used, or a combination of 281 or more types of polymerization machines can be used.

The polymerization temperature is preferably in the range of 60 to 200 t:, more preferably 60 to 140°C. The polymerization time is related to the amount of catalyst and is not particularly limited, but generally a polymerization time of 15 seconds or more and 20 minutes or less is selected. After a predetermined period of time has elapsed, the polymer taken out of the polymerization machine is in the form of lumps or powder, and some or all of the unreacted monomers are separated and supplied to the next step. The reaction system after polymerization is preferably ammonia, triethylamine,
Polymerization can be carried out by adding and mixing amines such as trilobylamine, hydroxides of alkali metals and alkaline earth metals, and other known catalyst deactivators, or by adding and treating a solution containing these deactivators. It is preferable to neutralize and deactivate the catalyst. In this case, if the produced polymer is in the form of a large lump, it is of course preferable to crush it immediately after polymerization.

The polymer thus obtained is further subjected to a stabilization process. In the case of an oxymethylene homopolymer, the stabilization treatment is performed by blocking the terminals by esterification, etherification, urethanization, etc., and in the case of a copolymer, heating and melting treatment or heating in an insoluble or soluble liquid medium, Achieved by selectively decomposing and removing unstable parts6
Furthermore, in the present invention, since the amount of catalyst used is extremely small, not only can a final product that has undergone a post-processing process have excellent thermal stability, but also the post-treatment stabilization process can be simplified, making it economical. It is advantageous.

[Example] Examples of the present invention are shown below, but the present invention is not limited thereto. The terms and measurement methods used in Examples and Comparative Examples are as follows.

% or pp■: All values are expressed by weight.

Polymerization yield: % of polymer obtained based on total monomers supplied (1 amount) Solution viscosity [reduced viscosity]: 0.5 g of polymer was dissolved in 100 mR of p-chlorophenol containing 2% α-pinene and measured using an Ostwald viscometer. Measurement was performed at 60°C using

Heating weight residual rate: pulverize 5g of polymer, 2,2-methylenebis(4-methyl-6-t-butylphenol)
(0.5% by weight) and dicyandiamide (0.1% by weight)
Mix well the stabilizer powder consisting of
It shows the weight remaining rate when heated for minutes.

Example 1 Too much of a 6G'C polyoxymethylene polymer previously dried under reduced pressure for 15 hours was charged into a separable flask having an internal volume of 11 and equipped with a gas blowing tube and a stirrer. Trifluoromethanesulfonic anhydride 0.0001 mol/1
A cyclohexane solution of is fed to the reactor at 1 ol/hour,
At the same time, helium gas is supplied from the gas blowing pipe at a rate of 50 per minute.
formaldehyde gas purified by a known method was blown at a rate of o, s g per minute using mm as a carrier.
The water content in Sentsumar is 80 ppm (by weight). 120 minutes after formaldehyde was started to be supplied, the polymer in the flask was taken out, washed with acetone, and dried. The catalyst concentration is 1 x 10-' relative to monomer;
The polymerization yield was 93%.

Examples 2 to 5 2 Kg of trioxane and 1.14° C. Mi of methylal as a molecular weight regulator were added in a vacuum chamber equipped with two Σ-type stirring blades with a jacket through which a heating medium could pass, and the temperature was 5 [1 rpm]. and at the same time raise the jacket temperature to 80℃.
It was adjusted to A catalyst solution (cyclohexane solution) shown in Table 1 was added to the catalyst concentration shown in Table 1 to initiate polymerization. The water content in trioxane is 10 ppm (
weight basis).

The time from when the catalyst was added until the system became cloudy (induction period) was measured. After 20 minutes, water ifl containing 1% triethylamine was added to the kneader, and after stirring for 1 hour, the contents were taken out and pulverized. The finely ground polymer was filtered, washed with acetone, and dried, and then the polymerization yield and reduced viscosity were measured. The results are shown in Table 1.

Example 6 Trioxane in Example 2 was replaced with 1.3-dioxolane, and trifluoromethanesulfonic anhydride was used as a catalyst at a molar ratio of 5 x 10 to 1.3-dioxolane.
An experiment completely similar to Example 2 was conducted, except that -' was set. The water content in 1,000 ml before polymerization was 9 ppm, and as a result of polymerization, the induction time was 22 seconds, and the polymerization yield was 97%.
The reduced viscosity was 1.99.

Comparative example 1.2 The water content in trioxane is 153 ppm, respectively.

215 ppm (II An experiment similar to Example 2 was conducted except that the weight was used as a basis. The results are shown in Table 1. Compared to the Example, the induction time was extremely long and the yield was also poor. was not polymerized at 215 ppm.

Examples 7 to 12 Instead of the trioxane monomer in Example 2,
The same procedure as Example 2 was carried out, except that trioxane containing 3.8 g% of 1.3-dioxolane was used as the monomer, and the super strong acid anhydride shown in Table 2 was added as a catalyst to the concentration shown in Table 2. Polymerization and post-treatment were performed in the same manner.

The properties of the obtained polymers are shown in Table 2. When these superstrong acid anhydrides are used as polymerization catalysts, high polymers can be obtained at low catalyst concentrations, and the molecular weight of the obtained polymers is high and thermal resistance is high. It is recognized that the stability is good.

Example 13 Polymerization and post-treatment were carried out in exactly the same manner as in Example 7, except that 1,4-butanediol formal was used instead of 1,3-dioxolane as a comonomer. Table 2 shows the results.
Shown below. In this case, almost the same results as above were obtained.

Example 14 Polymerization and post-treatment were carried out in exactly the same manner as in Example 7, except that 0.67% by weight of ethylene oxide was used instead of the comonomer 1,3-dioxolane.

The results are shown in Table 2. In this case, almost the same results as above were obtained.

Comparative Example 3 Polymerization and post-treatment were carried out in exactly the same manner as in Example 7, except that a large amount of catalyst was used. The thermal stability of the obtained polymer was extremely reduced.

Comparative Example 4 Trioxane 63g and 1,3-dioxolane 2.4g
was dissolved in cyclohexane IJ2, and the external temperature was maintained at 50°C. Trifluoromethanesulfonic anhydride was added at a molar ratio of I x 10''4 to all monomers.The inside of the system became cloudy 5 minutes and 20 seconds after the addition of the catalyst.

After 30 minutes, the slurry was filtered, pulverized in a 1% aqueous triethylamine solution, washed with acetone, and dried. The yield was 77%, and the heating weight residual rate was 74%.

Example 15 Has a cross section in which circles with an inner diameter of 50 wm partially overlap, L/D = 1
4, a continuous mixing reactor consisting of a jacketed barrel that allows a heat medium to pass through the outside, and two rotating shafts with a number of interlocking paddles inside the barrel, and hot water at 80°C in the jacket. The two rotating shafts were rotated in the same direction at a speed of 78 rpm. At one end, 3.8%
(by weight) of 1,3-dioxolane and trioxane containing 0.05% (by weight) of methylal were fed continuously at a rate of 1 g/hour.The water content in the mixture was 9 ppm. It was). At the same time, in the same place, trifluoromethanesulfonic anhydride dissolved in cyclohexane i (0
,001M) at 5.6mj/hour! The copolymerization was carried out by adding continuously at a rate of . The reaction mixture discharged from the other end was immediately poured into water containing 1% triethylamine to deactivate the polymerization catalyst, and then the polymer was dried. The polymerization yield was 92.1%, and the heating weight residual rate was 98.
．． It was 0%.

[Effects of invention

Claims (1)

[Claims] (1) Generally used as a polymerization catalyst in bulk polymerization using formaldehyde or its cyclic oligomer or cyclic acetal as a monomer, or one of these monomers as the main monomer, in the presence of a comonomer that can be copolymerized with these main monomers. Formula (F(CF_2)_nS
O_2)_2O (n = integer greater than or equal to 0) in a molar ratio of 1 x 10 to all monomers.
A method for producing an acetal polymer or copolymer, which is used in the range of ^-^8 to 5 x 10^-^6, and the water content in all monomers is 100 ppm (weight basis) or less.