JPH0229427A - Manufacture of polyoxymethylene - Google Patents

Abstract

PURPOSE:To produce a polyoxymethylene by adding a specific compound(s) in the (co)polymerization of trioxane or tetraoxane using a twin-screw mixer type polymerization reactor, thereby allowing the polymerization to be carried out stably for a long period of time. CONSTITUTION:When trioxane or tetraoxane is subjected to homopolymerization or copolymerization with comonomers to produce a polyoxymethylene using a twin-screw mixer type polymerization reactor, one or more compounds selected from the group consisting of esters of 2-40C carboxylic acids, amides of 2-40C carboxylic acids, alkali metal salts of 2-40C carboxylic acids, alkaline earth metal salts of 2-40C carboxylic acids, liquid paraffins, natural paraffins, microcrystalline waxes, polyethylene waxes, and fluorohydrocarbons are supplied. According to this process, the polymerization can be carried out continuously over a long period of time. Since the above additives are generally used to improve the flowability and the release properties of a thermoplastic resin in heat molding, a polymer produced finally is excellent in release properties.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for using +3A polyoxymethylene using trioxane or tetraoxane as the main raw material.

<Prior Art> Polyoxymethylene has a high degree of crystallinity and is known as an engineering glass with excellent mechanical properties.

Various methods are known for its production, but recently the most common method is to supply trioxane to a twin-screw mixer type polymerization reactor and carry out cationic bulk polymerization. Such a polymerization method is described, for example, in JP-A-56-38312.56.
-3831.3.56-59824.57-13911
3.58-3261.9.5832620.58-32
It is disclosed in Publication No. 621 and the like.

<Problems to be Solved by the Invention> However, although continuous polymerization is possible using the methods described in the above-mentioned publications, when the cylinder is operated for a long period of time, polymer gradually accumulates on the inner wall surface of the cylinder, and the tip of the paddle The clearance between the vehicle and the vehicle becomes almost 0, and a grating sound begins to occur. When a grating noise begins to occur, the stirring shaft becomes eccentric, the surface of the paddle is scraped, metal powder gets mixed into the polymer, causing it to turn gray, or the motor becomes overloaded and torques out. . Furthermore, when the scale comes off, the stirring state is disturbed, resulting in non-uniform particle diameters of the polymer powder and changes in the degree of polymerization.

Said Japanese Unexamined Patent Publication No. 56-38313.58-32619.58
-32620.58-32621 aims at preventing scaling by giving the tip of the paddle a special shape, but this alone is insufficient and stable operation over a long period of time has been difficult.

Means for Solving the Problems> In order to solve the above problems, the present inventors have made extensive studies and have discovered the present invention. When producing polyoxymethylene by homopolymerizing trioxane or tetraoxane or copolymerizing it with a copolymer component using a machine,
Esters of carboxylic acids having 2 to 40 carbon atoms, 2 to 4 carbon atoms
Amides of 0 carboxylic acids, alkali metal salts of carboxylic acids with 2 to 40 carbon atoms, alkaline earth metal salts of carboxylic acids with 2 to 40 carbon atoms, liquid paraffin, natural paraffin, microwax, polyethylene wax, fluorine-based carbonized This is a method for producing polyoxymethylene, characterized in that at least one species selected from hydrogen is supplied.

The polymerization reactor used in the present invention will be explained with reference to FIGS. 1 to 4. FIG. 1 schematically shows a state in which a stirring shaft equipped with a large number of paddles is arranged in a cylinder having a figure-eight cross section formed by overlapping two circles of different centers and the same diameter. FIG. 2 schematically represents a cross section perpendicular to the stirring shaft. The two stirring shafts are equipped with a large number of paddles each having a convex lens-shaped cross section.

There are two types of paddles: a flat type as shown in Figure 3 (^) and a helical type as shown in Figure 3 (8).By combining these paddles, it is possible to respond to phase changes in the reaction system. It is possible to create a feeding effect. In addition, in order to strengthen the anti-sagging ability, it is also possible to use a paddle with a scraper as shown in Figure 3 (C), or a pseudo-triangular paddle as shown in Figure 3 (CD). You can also. The clearance between the tip of the paddle and the paddle surface and cylinder inner wall surface is 2% or less, preferably 1% or less of the diameter of the circumscribed circle of the paddle. Further, the thickness of the paddle is preferably 1/20 to 1/4 of the diameter of the circumscribed circle of the paddle.

In the reactor used in the present invention, the feeding effect and kneading effect can be changed by changing the arrangement of the paddles.
It is necessary to consider the arrangement according to the desired conversion rate and degree of polymerization. When using a convex lens paddle, rotate the stirring shaft at 45° from the supply port toward the discharge port.
If the paddles are shifted by 45° in the direction opposite to the rotational direction, the feeding effect will be the largest. Further, when a helical type paddle is used, the feeding effect is increased, and when a reverse helical type paddle is used, the feeding effect is decreased.

The ratio of reactor length ([) to diameter CD), i.e. I-.

/D is preferably 32 or less, more preferably 15 or less,
More preferably, it is 6-12. Polymerization of trioxane or tetraoxane involves a significant phase change from liquid to slurry powder, and if the L/D is large, the stirring shaft will bend in the area where the phase change is large, or the torque will be applied abnormally, making operation impossible. becomes. If L/D is small, the residence time will be short and the conversion rate will be low, which is economically disadvantageous.

The reaction temperature is preferably 40 to 150°C, more preferably 50 to 110°C. Temperature control can be achieved by providing a jacket outside the cylinder to circulate hot or cold water.

If the reaction temperature is low, the conversion rate will be low, and if it is not high, depolymerization will proceed competitively and the degree of polymerization will decrease, so care must be taken.

The trioxane or theraoxane used in the present invention may be supplied in a solid or crystalline state or in a molten state, but it is preferably supplied in a molten state.

Further, in the present invention, trioxane or tetraoxane can be homopolymerized or copolymerized with other copolymerization components.

Examples of the copolymerization component in this case include cyclic ethers and olefins, but cyclic ethers represented by the general formula (^) are preferred.

y2-e-.

Y3-C-(X)m Y4 (A) (However, in the formula, Y1 to Y4 are hydrogen atoms, carbon atoms 1' to
6 alkyl groups and halogen-substituted alkyl groups having 1 to 6 carbon atoms, each of which may be the same or different by 6. Further, X represents a methylene or oxymethylene group, which may be substituted with an alkyl group or a halogen-substituted alkyl group, and m represents an integer of 0 to 3. Or, X is -
(CH2) p-0-CI-(2- or -〇-CH2
-(CH2)P-0-CH2- may be used, in which case m=1, and P is an integer from 1 to 3. ).

Among the cyclic ethers represented by the above general formula (A), particularly preferred compounds are ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-dioxane, 1,3-dioxolane, 1.3.5-1 -rioxepane, ]-,3,6-drioquincan, epichlorohydrin, and the like.

The copolymerization amount of the cyclic ether of the present invention needs to be in the range of 0.1 to 15 mol%, particularly preferably 0.2 to 5 mol%, based on trioxane or tetraoxane.
If it is less than 0.1 mol %, the yield of the polymer when stabilized by decomposing and removing the unstable end portion is low, which is undesirable because it reduces productivity. Moreover, if it is more than 15 mol %, the melting point and crystallinity of the polymer will decrease, and the mechanical strength and moldability will deteriorate, which is not preferable.

In the polymerization catalyst of the present invention, one or more compounds selected from the group of boron trifluoride, boron trifluoride hydrate, and coordination compounds of boron trifluoride and an organic compound having an oxygen or sulfur atom, It can be used in gaseous, liquid form or as a solution in a suitable organic solvent.

Examples of the organic compound having an oxygen or sulfur atom that forms a coordination compound with boron trifluoride include alcohol, ether, phenol, and sulfide.

Among these catalysts, coordination compounds of boron trifluoride are particularly preferred, and boron trifluoride/diethyl etherate and boron trifluoride/dibutyl etherate are particularly preferably used.

Examples of the solvent for the polymerization catalyst of the present invention include aromatic hydrocarbons such as benzene, toluene, and xylene, n-hexane, and n-hexane.
- aliphatic hydrocarbons such as hebutane, cyclohexane,
Alcohols such as methanol and ethanol, halogenated hydrocarbons such as chloroporum, dichloromethane and 1,2-dichloroethane, and ketones such as acetone and methyl ethyl getone are used.

The amount of polymerization catalyst added is 5 to 1 mole of trioxane.
It is in the range of X10-6 to lXl0-1 mol, particularly preferably in the range of lXl0-5 to lXl0-2 mol.

Number of carbon atoms used in the production method of the present invention is 2 to 40
Carboxylic acid esters, alkali metal salts of carboxylic acids with 2 to 40 carbon atoms, alkaline earth metal salts of carboxylic acids with 2 to 40 carbon atoms, liquid paraffin, natural paraffin, microwax, polyethylene wax, and fluorinated hydrocarbons are generally is added to improve the fluidity and mold release properties of thermoplastic resins during hot molding.

A large number of such compounds are known.

Examples of esters of carboxylic acids having 2 to 40 carbon atoms include glycerin monostearate, polyethylene glycol monostearate, methyl 12-hydroxystearate,
Examples include cetyl palmitate, montanic acid ethylene glycol ester, montanic acid butylene glycol ester, and oleic acid monoglyceride.

Amides of carboxylic acids having 2 to 40 carbon atoms include ethylene bis stearamide, stearamide, pallic acid amide, oleylamide, methylene bis stearamide, and the like.

Examples of the alkali metal salt or alkaline earth metal salt of carboxylic acid having 2 to 40 carbon atoms include sodium montanate;
Potassium Montanate, Magnesium Montanate, Calcium Montanate, Sodium Behenate, Potassium Behenate, Magnesium Behenate, Calcium Behenate, Sodium Stearate, Potassium Stearate, Magnesium Stearate, Calcium Stearate, Barium Stearate, Storo Stearate ] Partial saponification of lithium, montanic acid lyceride 1 Of course, partial saponified products of montanic acid ethylene glycol ester, etc. can be mentioned.

In addition, fluorine-based hydrocarbons refer to hydrocarbons that have a structure in which a fluorine atom or carbon is directly bonded, and specifically, potassium perfluoroalkylsulfonate, sodium perfluoroalkylsulfonate, perfluoroalkylsulfonate Lithium acid, polyoxyethylene perfluoroalkyl ether, disodium N-perfluorooctanesulfonylglutamate, sodium 3-fluoroalkyloxy-1-alkylsulfonate, 3-
(ω-Fluoroalkanoyl-N=ethylamino-1-
Sodium propanesulfonate, N-((3-perfluorooctanesulfonamido)propyl)-N.

N-dimethyl-N-carboxymethylene ammonium betaine, perfluorooctanesulfonic acid jetanolamide, N-propyl-N-(2-hydroxyethyl)
Perfluorooctane sulfonamide, perfluoroalkyl-N-ethylsulfonylglycine potassium salt, bis(N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate, perfluoroalkylethyl phosphate, polytetrafluoroethylene, tetrafluoro Examples include ethylene/hexafluoropropylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and tetrafluoroethylene/ethylene copolymer.

Esters of carboxylic acids having 2 to 40 carbon atoms, amides of carboxylic acids having 2 to 40 carbon atoms, and 2 to 40 carbon atoms used in the present invention
~40 carboxylic acid alkali metal salt, carbon number 2-40
alkaline earth metal salts of carboxylic acids, liquid paraffin,
Natural paraffin, microwax, polyethylene wax, fluorine-based carbonized, q It may be supplied to the polymerization reactor after being dissolved or suspended in an organic solvent, or it may be supplied as it is.

In addition, the supply amount is trioxane or tetraoxane 10
It is preferably 0.01 to 30 parts by weight, more preferably 061 to 10 parts by weight. If it is less than 0.01 part by weight, the effect of addition will be small, and if it exceeds 30 parts by weight, the mechanical properties of the polymer will deteriorate, which is not preferable.

<Example> The present invention will be explained below with reference to Examples.

The polymerization reactor used in Examples and Comparative Examples had an inner diameter of 100 mt+φ and L/D=10.2. Also,
The arrangement pattern of the paddles is shown in Figure 4. The numbers shown in FIG. 4 represent the deviation angle (°) in the rotational direction of the stirring shaft when looking at the discharge port from the raw material supply port.

Examples 1 to 20 Polymerization was carried out for a long time under the conditions shown in Table 1, and the presence or absence of breast milk sound was determined.
The size of the obtained polymer powder was examined. Furthermore, bis(1,2,2,6,6
A solution of 0.27 parts by weight of -bentamethyl-4-piperidinyl) Sebage 1~ (Nol LS765 manufactured by Ciba Geigy) dissolved in 2 parts by weight of benzene was added, and the mixture was stirred and pulverized for 15 minutes in a Henschel mixer to catalyze the catalyst. It was deactivated. Furthermore, triethylene glycol bis[3-(:
3-t-butyl-5-methyl-4hydroxyphenyl)
Propionate] (Irganox 245 manufactured by Ciba Geigy > 0.5 parts by weight, calcium stearate 0.
1 part by weight and 0.1 part by weight of melamine were added and melted and stabilized at 230°C/50 rpl in a Laboplastomill manufactured by Toyo Seiki Co., Ltd., and the MI (melt index) of the obtained polymer was adjusted to a load of 2.160. g, measured at a temperature of 190°C.

Comparative Examples 1-4 Example 1.11.15 except that no mold release agent was supplied
．． Polymerization and melt stabilization were carried out in the same manner as in No. 17. The results are shown in Table 2.

Comparative Examples 5 to 8 Polymerization and melt stabilization were carried out in the same manner as Comparative Examples 1 to 4 except that a paddle equipped with a scraper as shown in FIG. 3(C) was used. The results are shown in Table 2.

Comparative Examples 9 to 12 Polymerization and melt stabilization were carried out in the same manner as Comparative Examples 1 to 4, except that a pseudo-triangular paddle as shown in FIG. 3(D) was used. The results are shown in Table 2.

From Examples 1 to 10, it can be seen that long-term continuous operation is possible regardless of the type, supply amount, and supply method of the mold release agent. Furthermore, the particle size of the polymer powder was fine and the quality was uniform.

From Examples 11 to 14, long-term continuous operation was possible even if the copolymerization components were changed. Moreover, from Examples 15 and 16, it can be seen that there is no problem even if the amount of raw materials supplied is halved.

Examples 17 to 20 show that long-term continuous operation is similarly possible even if the main raw material is changed from trioxane to tetraoxane.

From the ratio 1 bite cases 1 to 4, it can be seen that long-term continuous operation is impossible unless a mold release agent is supplied.

From Comparative Examples 5 to 8, it can be seen that even if a paddle equipped with a scraper as shown in FIG. 3(C) is used, long-term continuous operation is impossible unless a mold release agent is supplied.

From Comparative Examples 9 to 12, it can be seen that even if a pseudo-triangular paddle as shown in FIG. 3(0) is used, long-term continuous operation is impossible unless a mold release agent is supplied.

<Effects of the Invention> By carrying out the production method of the present invention, trioxane or tetraoxane can be polymerized continuously over a long period of time. Furthermore, since a mold release agent is added during polymerization, the final polymer obtained has poor mold releasability.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a two-shaft reactor, Fig. 2 is a cross-sectional view of the main part of the two-shaft reactor in a direction perpendicular to the stirring shaft, and
Figure (^) is a schematic diagram of a flat type paddle, Figure 3 (B) is a schematic diagram of a helical type paddle, Figure 3 (C) is a schematic diagram of a flat type paddle with a scraper, and Figure 3 (D) is a schematic diagram of a flat type paddle. FIG. 4 is a schematic diagram of a triangular flat paddle, and FIG. 4 is a block diagram showing the paddle pattern. 1: Stirring shaft, 2: Body, 3: Jaguette, 4: Supply port, 5: Paddle, 6: Discharge port, 7: Feed screw

Claims (2)

[Claims] (1) When producing polyoxymethylene by homopolymerizing trioxane or tetraoxane or copolymerizing with a copolymer component using a twin-screw mixer type polymerization reactor, esters of carboxylic acids having 2 to 40 carbon atoms are used. , carbon number 2
Amides of ~40 carboxylic acids, alkali metal salts of carboxylic acids with 2 to 40 carbon atoms, alkaline earth metal salts of carboxylic acids with 2 to 40 carbon atoms, liquid paraffin, natural paraffin, microwax, polyethylene wax, fluorine-based A method for producing polyoxymethylene, which comprises supplying at least one kind selected from hydrocarbons. (2) The polymerization reactor is equipped with a jacket for temperature control around the outer periphery of the cylinder, and each of the two stirring shafts has a plurality of plate-shaped paddles fixed so as to be in contact with each other, and each paddle is connected to the other. Each paddle is arranged to rotate with a slight clearance between its tip, the facing paddle surface, and the cylinder inner wall surface, facing one of the other paddles fixed to the stirring shaft of the The manufacturing method according to claim 1, characterized in that: