JP2958259B2 - 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 with respect to all monomers), and it is difficult to sufficiently deactivate the catalyst after polymerization. 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 involved in the deactivation treatment of the catalyst, a method has been proposed in which the amount of the deactivator solution added is reduced and washing of the crude polymer is also omitted (for example, Japanese Patent Application Laid-Open No. 52285/1982). No.
JP-A-57-80414, JP-A-62-285909, JP-A-63-27519), and in such a method, a conventionally known polymerization catalyst such as a boron trifluoride-based catalyst is used.
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 the polymerization is increased, the necessity of washing and recovering the monomer is reduced, but the produced polymer becomes more unstable, and a complicated stabilization treatment is required in a subsequent step, which simplifies the step. However, the stability is limited and the quality is not desirable.

[0003]

In view of the above situation, the present inventors can easily deactivate a catalyst with a small amount of a deactivator solution, and a simple process without a washing step. It is an object of the present invention to produce a polyacetal copolymer which has very few unstable terminal portions even at a high polymerization yield and is extremely stable thermally.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the use of a heteropolyacid or an acid salt thereof as a catalyst has high polymerization activity as a characteristic of the catalyst. Nevertheless, deactivation by the deactivator can be performed very easily and reliably.
The inventors have found that the above object can be achieved, and have completed the present invention. That is, the present invention provides a polyacetal copolymer by copolymerization with a cyclic ether or cyclic formal having trioxane as a main monomer and having at least one carbon -carbon bond as a comonomer as a part of a ring component. In the production, copolymerization is carried out using a heteropolyacid represented by the following general formula (1) or an acid salt thereof as a polymerization catalyst, and a residual monomer is added to all supplied monomers.
After reducing the amount to 10% by weight or less, a solution containing a catalyst deactivator is added to the resulting crude polymer in an amount of 0.01 to 10% by weight to deactivate the catalyst, and then the crude polymer is heated and melted without being washed. And a method for producing a polyacetal copolymer.

[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 with a very small amount and 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. Very few,
An object of the present invention is to obtain a polyacetal copolymer which is extremely stable thermally. In the case of a conventional boron trifluoride-based catalyst or the like, it is difficult to avoid harmful effects such as decomposition by a substance derived from the catalyst even after its deactivation, but 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). Furthermore (1) Hx can be used in the catalyst of the acid salt form that has changed-out part measures such various metals present invention in the expression. 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 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 suppressed to a small extent, unstable formate end groups, hemiacetal
An effective generation of such terminal groups to you suppressed, also economically advantageous. In the present invention, the above-mentioned catalyst is preferably 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 conduct the reaction.As the diluent, the heteropolyacid is soluble. ethers are organic solvents, for example n- but-butyl ether, or the like are preferred diluents, is rather than being limited thereto, below
Predetermined amount for some or all of monomers and molecular weight regulators
It is also preferable to add
It is a good method.

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. Further, the polymerization reaction system is desirably in a state where impurities having active hydrogen, for example, water, methanol, formic acid, and the like are substantially not present.

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,
It is necessary that the amount of unreacted monomer after polymerization is 10% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less.
% 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 monomers, it is generally sufficient to raise the polymerization rate to a certain level or more. This can be easily achieved by appropriately adjusting the amount of the catalyst used in the present invention 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 even a small amount of catalyst can be achieved in a relatively short time. 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 copolymerization reaction is completed, and the remaining monomer is reduced to 10
A predetermined amount of a solution containing a catalyst deactivator is added to and mixed with the crude polymer of not more than weight% to deactivate the catalyst. The deactivator in the present invention may be in an amount sufficient to neutralize and deactivate the catalyst, and is preferably added as a deactivator solution in which the deactivator is dissolved or dispersed in water or an organic solvent. in this case,
The amount of the deactivator solution is 0.01 to 10% by weight based on the weight of the crude polymer.
, Preferably 0.05 to 5% by weight, particularly preferably 0.
1 to 3% by weight. According to the present invention, the amount of the quenching liquid is characterized in that it is extremely small, and the amount is quite insufficient for the crude polymer to be immersed into a slurry, but the specific amount used in the present invention is In combination with the characteristics of the polymerization catalyst, the catalyst can be sufficiently deactivated even in such a small amount by sufficiently stirring and mixing with the crude polymer, and even if the product derived from the deactivated catalyst remains, The present invention is characterized in that a stable polyacetal copolymer can be obtained by heating and melting as it is, without causing adverse effects such as accelerated decomposition of the coalescence and without separating and washing the deactivated liquid.

The deactivator used in the present invention includes:
Any known basic substance similar to the case of the conventional boron trifluoride catalyst or the like is effective, for example, ammonia, various amine compounds, a trivalent phosphorus compound, or an oxide of an alkali metal or an alkaline earth metal, Hydroxides, organic acid salts and inorganic acid salts. These deactivators are added as an aqueous solution or an organic solvent solution in a range of a certain amount or less.
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.
Examples of the trivalent phosphorus compound include, for example, triphenylphosphine. Further, as the alkali metal or alkali metal compound, an alkali metal or alkaline earth metal oxide, hydroxide, carbonate, bicarbonate, phosphate, borate, inorganic weak acid salt such as silicate, Organic acid salts such as acetate, oxalate, formate, benzoate, terephthalate, isophthalate, phthalate and fatty acid salt, methoxide, ethoxide, n-butoxide, sec-butoxide, tert-butoxide and the like Of these, hydroxides, carbonates, and fatty acid salts are preferably used. As the alkali metal or alkaline earth metal component, lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium and the like, among which lithium,
Sodium, potassium, magnesium and calcium are preferably used. Specifically, calcium hydroxide, magnesium hydroxide, sodium carbonate, calcium acetate, calcium stearate, calcium 12-hydroxystearate and the like are particularly preferred.

As a solvent for dissolving the deactivator, water or an organic solvent is used. As organic solvents, alcohols such as methanol and ethanol, ketones such as ethyl ketone and acetone, benzene, toluene, aromatic compounds such as xylene, cyclohexane, n-hexane,
and saturated hydrocarbons such as n-heptane. Water is particularly preferred. The method of adding the deactivator solution to the crude polymer is not particularly limited, but it is preferable to spray the solution onto the crude polymer or to mix well with the solution after the addition of the solution in order to effect the dispersion contact effectively. Further, at the time of deactivation treatment of the catalyst, it is preferable 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. 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 deactivation temperature is 20 to 120 ° C, preferably 40 to 100 ° C. Particularly at this stage by treating at a relatively high temperature, it is also possible to partially remove the unstable portion of the crude copolymer, especially when using a solution of an amine compound or an aqueous ammonia solution as a deactivator. The effect is remarkable.

Further, in the method of the present invention, if necessary ,
In general, it is preferable to mix other necessary stabilizers after deactivation of the crude polymer or at the same time as the deactivation treatment, and to carry out heat melting treatment in the presence of them . As the stabilizer, the substance exemplified as the quenching agent often has the function as a stabilizer component as it is, but other substances known as stabilizers for conventional polyacetal resins, such as various hindered It is important to add a phenolic antioxidant and the like, and various nitrogen-containing compounds, metal oxides and fatty acid salts may be added and used together. 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-tert-butyl-4-hydroxyhydrocinamamide),
2-tert-butyl-6- (3'-tert-butyl-5'-methyl-
2'-hydroxybenzyl) -4-methylphenyl acrylate, 3,9-bis [2-{(3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy}
[1,1'-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] -undecane, and the like. These chicks
Some or all of the darn phenolic antioxidants
Is added to trioxane or comonomer before polymerization
And may be present during polymerization. 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, 1
2, 6/12, 6/66/610, 6/66/610/12). Examples of the metal fatty acid salt include a calcium salt or a magnesium salt of a higher fatty acid. Metal oxidation
Examples of substances include calcium oxide and magnesium oxide.
I can do it. 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.

In the present invention, the crude polymer to which a catalyst deactivator or the like has been added is then subjected to a heat melting treatment. The heat 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. If the temperature is higher than 250 ° C., decomposition of the polymer occurs, 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. According to the present invention, in this melt-kneading treatment, the polymerization catalyst is completely deactivated, and the mixed deactivator solution promotes the decomposition and desorption of the unstable terminal portion of the crude polymer, and is used as a deactivator. Water and other solvents and residual monomers are removed from the vent together with the added water, 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.

[0016]

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 to 3 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, at the same place, 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 outlet of the polymerization machine was subjected to polymerization by another apparatus (partially collected and the amount of residual monomer was measured), and then the quenching agent solution shown in Table 1 was added. And simultaneously pulverize through a pulverizer,
The mixture was stirred at 60 ° C. for 30 minutes (90% or more was 2 mm or less in particle size). Then, tetrakis- [methylene-3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate] 0.5% of methane and 0.2% of melamine were added, and the mixture was stirred and mixed in a Henschel mixer for 5 minutes. The mixture was melt-kneaded at a degree of vacuum of 5 mmHg and extruded to form pellets. 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).

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

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.

Continuation of the front page (56) References JP-A-1-170610 (JP, A) JP-A-63-27519 (JP, A) JP-A-57-80415 (JP, A) JP-A-52-57285 (JP, A) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 2/00-2/38

Claims (6)

(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 the residual monomer was adjusted to 10% by weight or less based on the total amount of the supplied monomers, a solution containing a catalyst deactivator was added to the crude polymer at a concentration of 0.
A method for producing a polyacetal copolymer, which comprises adding 01 to 10% by weight to deactivate a catalyst, and then subjecting the crude polymer to heat melting treatment without washing. 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. A solution containing a catalyst deactivator, wherein ammonia, an amine compound, a trivalent phosphorus compound, or an alkali metal or alkaline earth metal oxide, hydroxide, inorganic salt or organic compound is used as the deactivator. The method for producing a polyacetal copolymer according to any one of claims 1 to 3, wherein the solution is an aqueous solution or an organic solvent solution containing at least one compound selected from acid salts. 5. 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. 6. The method for producing a polyacetal copolymer according to claim 1, wherein a heating and melting treatment is further performed by adding a stabilizer.