JPS59136315A - Production of formaldehyde copolymer - Google Patents

Abstract

PURPOSE:To produce the titled copolymer stably for a long period, in high yield, by reacting formaldehyde with cyclic formal in the presence of boron trifluoride, cooling the produced copolymer with a cooler having a particular structure, and recycling a part of the copolymer to the reactor. CONSTITUTION:In the first stage, formaldehyde, cyclic formal, 0.1-20pts.wt., based on 100pts.wt. of formaldehyde, of an inert organic solvent, boron trifluoride as a catalyst, and a formaldehyde copolymer recycled from the second stage, are supplied to a twin-screw mixer kneader to effect the copolymerization. The produced copolymer is supplied continuously to a cooler 11. A part of the copolymer corresponding to the produced copolymer is taken out of the system, and the rest part thereof is recycled to the first stage. The cooler 11 used in the second stage has a stirring shaft 12 extending through the lower side wall and furnished with stirring blades, and a rotary shaft 17 extending through the upper side wall of the cooler and furnished with a cooling member 16 through which a coolant is passed. EFFECT:The deposition of the copolymer to the cooler can be remarkably suppressed.

Description

[Detailed description of the invention] The present invention relates to a method for making formaldehyde copolymers.

A method of copolymerizing formaldehyde and cyclic formal in the gas phase in the presence of boron trifluoride is known (see Japanese Patent Publication No. 7554/1983).

The copolymer obtained by this method has a low molecular weight of 2 and low stability in a basic medium, as can be seen from the results of the examples in the above-mentioned publication, and cannot be put to practical use.

Japanese Patent Publication No. 44-870 discloses a method of copolymerizing formaldehyde and a comonomer in a gas phase in the presence of an amine in a one-turn reactor.

When this method is carried out industrially, the polymer adheres to the walls of the reactor within a short period of time, and smooth operation becomes impossible.

To prevent polymer adhesion to the reactor walls.

It is conceivable to use a self-cleaning twin-shaft mixer that has been proposed as a copolymerization reactor for trioxane and cyclic formal. According to experiments conducted by the present inventors, when formaldehyde and cyclic formal are copolymerized using this twin-shaft mixer, the activity of boron trifluoride or its ether complex used as a catalyst is low, resulting in low productivity. And.

A problem arose that the resulting copolymer had poor stability in basic media. In addition, a large amount of polymerization heat is generated in the copolymerization of Pol 1, aldehyde, and cyclic formal;
Since the heat transfer area of the twin-screw mixer is small, the heat of polymerization cannot be completely removed.

Therefore, it is necessary to adopt an external circulation cooling method in which the copolymer discharged from the twin-screw mixer is cooled by passing it through an external circulation cooler and then returned to the above-mentioned stirrer. For this purpose, known coolers 5 are used, for example stirred coolers with cooling jackets.

Formaldehyde copolymer adheres to the inner wall of the cooler and the stirrer, resulting in problems such as a decrease in the cooling function and an increase in the load on the stirring power.

The present invention provides a method for all at once solving the above-mentioned problems when copolymerizing formaldehyde and cyclic formal.

The present invention relates to formaldehyde and cyclic formal.

0.1 to 20 parts by weight of an inert organic solvent per 100 parts by weight of formaldehyde and formaldehyde copolymer recycled from the second step described below are continuously fed to a twin-screw mixer, and the above formaldehyde and the formaldehyde are mixed in the presence of boron trifluoride. The first step is to copolymerize with cyclic formal and continuously discharge the formaldehyde copolymer, and a plurality of stirring shafts equipped with stirring blades are provided passing through the lower side wall, and the bottom wall is connected to the tip of the stirring blade. The formaldehyde from the first step is passed through the cooler, which is composed of a partially cylindrical part along a locus, and has a rotating shaft that passes through the upper side wall and is equipped with a disk-shaped cooling member through which a cooling medium flows. A second step in which the copolymer is continuously supplied and cooled, the copolymer corresponding to the amount produced is extracted, and the remainder is returned to the first step.
This is a method for producing formaldehyde copolymer consisting of steps.

According to the present invention, a formaldehyde copolymer having excellent stability in a basic medium can be obtained in high yield.

Furthermore, according to the present invention, adhesion of the copolymer to the cooler is significantly suppressed.

The copolymer can be produced stably over a long period of time.

Next, one embodiment of the present invention will be explained based on an embodiment shown in the drawings.

A twin-shaft mixing stirrer 1 used as a first step polymerization reactor is composed of an outer case 2 and two horizontal stirring shafts 4 equipped with a large number of elliptical mixing stirring blades. As shown in FIG. 2, when the stirring shaft 4 is rotated, the mixing stirring blades 3 have a small gap 2 between the other surface and the inner wall of the outer case 2, usually a gap of 0.5 to 5 degrees. form. Such a twin-shaft mixer 1 is available from 2, for example, KRO from Kurimoto Iron Works.
It is commercially available as Kneader.

Formaldehyde, cyclic formal, inert organic solvent and boron trifluoride are fed through tubes 20.degree. 21.22 and 23, respectively. The formaldehyde copolymer (hereinafter simply referred to as "copolymer") from the second step is transferred to tube 2.
Supplied from 4.

The moisture content of formaldehyde is preferably 0.1 weight or less, particularly 0.01 weight or less.

Formaldehyde is subjected to the reaction in a gas phase.

As a cyclic formal.

The compound represented by and the compound represented by
Ft, 'R3 and R4 each represent hydrogen, an alkyl group, an allyl group and a cycloalkyl group, m is 1
~B is an integer, and n is an integer from 2 to B. ) is used. Specific examples include ethylene oxide, propylene oxide, epichlorohydrin, shrimp glomohydrin,
Butene-1-oxide, 1,3-butadiene-1-oxide, styrene oxide, d-methylstyrene oxide, oxetane, tetrahydrofuran, 1. Ro-
Dioxolane.

4-phenyl-1,3-dioquinrane, 2-methyl-1
, 3-dioxolane, 2-phenyl-1,3-dioquinane, 1,6-dioquinpane, 2-butyl-1, ro-dioquinpane, 1,3.6-) rioquincane.

1.3.5-) Lioxopane and polyethylene glycol formal are mentioned. The amount of cyclic formal used is 0.001 to 0 per mole of formaldehyde supplied.
．． It is preferably 1 mol, especially 0.01 to 0.04 mol. When using a cyclic formal that is liquid at room temperature, it is preferable to preheat it to a gaseous state and use it for the reaction.

A specific example of an inert organic solvent is pentane.

Examples include aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, benzene, toluene, xylene natonoaromatic hydrocarbons, and rogogenated products of these hydrocarbons. It is preferable that the inert organic solvent is subjected to the reaction in a gaseous state. What is the amount of inert organic solvent used?

0.1 to 20 per 100 parts by weight of formaldehyde supplied
Parts by weight, preferably 0.5 to 5 parts by weight.

If the amount used is less than the lower limit, the activity of boron trifluoride or its ether complex used as a catalyst will be greatly reduced, and the resulting copolymer will have low stability in a basic medium. Even if the amount used is larger than the upper limit, the stability of the resulting copolymer in a basic medium will not be further increased, and the cost of recovering the inert organic solvent will increase.

Boron trifluoride may be used as it is, or may be used as a complex with an ether such as dimethyl ether or diethyl ether. The amount of boron trifluoride used is usually 1 x 10 to 1 x 1 per mole of formaldehyde supplied.
It is 0 mole.

When using a boron trifluoride ether complex that is liquid at room temperature, it is preferable to bring it into a gas phase beforehand and use it for the reaction.

Boron trifluoride can be used in combination with metal chelate compounds. Examples of metal chelate compounds include 2, for example,
No. 0-7073, No. 42-958, No. 42-
No. 7629, No. 42-22068, No. 42-
Publication No. 1934'o.

A chelate compound described in Japanese Patent Publication No. 49-35839 is used. Typically +C! u+ Cot Fe+
Examples include chelate compounds having a metal such as Ni+V as a central atom and a ligand such as β-diketones, aromatic oxydialdehydes, condensates of aromatic oxydialdehydes and diamines, and the like. The amount of the metal chelate compound used is 0.5 mol or less, particularly 0.05 to 0.5 mol, per 1 mol of boron trifluoride.
Preferably it is 0.5 mol. By using metal chelate compounds in combination.

The stability of the resulting copolymer in basic media is much improved. The metal chelate compound is dissolved in an inert organic solvent or liquid cyclic formal and subjected to the reaction.

The amount of copolymer circulated through tube 24 is:

It varies depending on the polymerization heat to be removed in the second step, but 2
It is usually 50 to 200 times the weight of formaldehyde fed.

A copolymerization reaction between formaldehyde and cyclic formal is carried out in a twin-shaft mixer 1 in which a stirring shaft 4 and stirring blades 3 are driven by a motor (not shown). The polymerization temperature is usually 40 to 80°C. The space velocity of formaldehyde in the stirrer 1 is usually 300 to 2000 h,
The average residence time of the copolymer is usually 5 to 30 seconds.

The produced copolymer is discharged through tube 25 together with the circulating copolymer.

Two stirring shafts 12 are provided in the lower part of the second process cooler 11 so as to extend in parallel through the side wall 13 of the cooler.

The interval between the two stirring shafts 12 is preferably such that the trajectories (rotating circles) of the tips of the stirring blades 15 provided on the shafts via the support 14 touch or overlap. Three or more stirring shafts can be installed, but there is no significant difference in mixing performance, so
For practical purposes, two axes are sufficient.

There are no particular restrictions on the shape of the stirring blades 15.

Paddle vanes are generally used to sweep the powdered copolymer upwardly within the cooler 11. For the purpose of scraping up the powdered copolymer, the paddle blade is attached to the stirring shaft 1.
2 is preferred, but in order to create a gentle circulation flow throughout the cooler 11, the paddle blades may be inclined or a horizontal blade and an inclined blade may be combined.

A plurality of stirring blades 15 are mounted symmetrically on the stirring shaft. 6
Single blades or four blades may also be used, but two blades spaced 180 degrees apart is usually sufficient. The spacing between the stirring blades 15 in the axial direction is also arbitrary, but from the point of view of the stirring effect, it is preferable that they be close to each other, and they are usually installed at intervals of 1.1 to 10 times the blade width. The relative position of the stirring blades 15 between the two shafts is such that both blades do not come into contact with each other due to rotation.

The bottom of the cooler 11 is formed of a partial cylinder located in the locus of the tip of the stirring blade 15. The limit for partial cylinders is up to 1/2 cylinder. That is, when the tips of the stirring blades 15 are spaced apart from each other (d), at the bottom of the cooler 11 in the middle part,
A chevron-shaped connection is provided to prevent copolymer retention. The smaller the gap between the bottom of the cooler 11 and the tip of the stirring blade 15 (11), the better, and is generally 10 or less.

It is desirable that the height of the cooler 11 is greater than the height of the powdered copolymer that has been stirred and floated.
Preferably 1.2 times or more the diameter of the maximum rotation circle drawn by .
It is 5 to 3.5 times. The length in the axial direction of the cooler 11 is arbitrary, but it is usually 1 to 7 times the diameter of the rotating circle, especially 1.5 to 7 times.
5 times is appropriate.

A rotating shaft 17 to which two disc-shaped cooling members 16 are attached is provided at the upper part of the cooler 11, passing through the side wall 1.

The rotating shaft 17 is installed parallel to the stirring shaft 12. Further, the one-rotation shaft 17 is provided so that the lower end of the cooling member 16 attached thereto is near the highest point of the trajectory of the stirring blade 15. The size and number of cooling members 16 can be easily determined by those skilled in the art, taking into consideration the amount of heat to be removed.

The interiors of the cooling member 16 and the rotating shaft 17 have a structure in which a cooling medium flows, as shown in FIG. 4, for example. A rotary joint 18 is attached to one end of the rotating shaft 17, and the cooling medium is supplied to the cooling member 16, and after heat exchange, is discharged through the rotating shaft 17 (12).

The powdered copolymer from the first step is fed through tube 25. The stirring shaft 12 is driven by a drive device (not shown). The rotational speed of the stirring blades 15 is determined in consideration of the size of the cooler 11, the size and number of blades, etc. In order to obtain a sufficient stirring effect, generally the height of the powdered copolymer in the cooler 11 should be approximately 0.5 to 2 times the rotational diameter of the stirring blade 150 at the height of the top end of the stirring blade 15. The rotation speed is adopted such that This generally corresponds to a linear velocity of 1 to 5 m and 7 seconds at the tip of the stirring blade 15.

The amount of powdered copolymer in the cooler 11 may be any amount as long as a sufficient stirring effect can be obtained, but the amount below the position near the highest point drawn by the stirring blade 15 when the stirring blade 15 is stopped is sufficient. It is preferable that there be.

Inside the cooler 11, the powdered copolymer is stirred up by the stirring blades 15 to form a forced circulation flow. The upper surface of this forced circulation flow is preferably located above the highest point of the cooling member 16 in order to efficiently remove the heat of double polymerization.

The rotating shaft 17 is rotated by a drive device (not shown). The rotational speed of the rotating shaft 17 is preferably 0.3 to 6 m/sec as the linear velocity of the tip of the cooling member 16 in order to increase the speed of collision between the powdered copolymer and the cooling member 16.

Polymerization heat is removed by the wall of the cooler 11 and the cooling member 16. In particular, two aspects of the present invention.

By installing the cooling member 16 in the forced circulation flow generated by the intense scraping or splashing effect of the stirring blades 15, the powdered copolymer collides violently with the entire cooling member 16, and furthermore, the heat transfer surface itself rotates. This increases the sliding force of the powder, and the heat transfer surface uniformly contacts the fluid. Therefore, there is less adhesion of the powdered copolymer to the heat transfer surface, the heat transfer surface can be easily renewed, the heat transfer coefficient can be increased by disturbing the boundary surface, and the heat of polymerization can be efficiently removed.

The cooled powdered copolymer is discharged through tube 24.

An amount of copolymer commensurate with the produced copolymer is withdrawn as a product from tube 26, and the remaining copolymer is returned to the first step through tube 24.

In the present invention, the powder copolymer transfer pipe 24°25
It is preferable to use forced transfer pipes such as screw conveyors as and 26.

Next, examples will be shown.

The intrinsic viscosity of the copolymer was measured at 6°C using p-chlorophenol containing 2 parts by weight of α-pinene as a solvent. The base stability of the copolymer is defined as the base stability of the copolymer in benzyl alcohol containing 1% by weight of 1.
Copolymer concentration 10 This is the recovery rate (%) of copolymer when heat treated with heavy fa candy at 160°C for 1 hour.

Example 1 A KRC kneader 4=4 with a hopper manufactured by Kurimoto Iron Works was used as a polymerization reactor, and the cooler shown in Fig. 1 was used.

It has the shape shown in Figures 5 and 4 and has a height of 475gH.
+ Width 440 mm, length 1 + OOO? iml internal volume approx. 1
A 5US304 cooler of 92.34 was used.

A disk-shaped cooling member (outer diameter 20 ofllml) is attached to the cooler piece.
sU 5 (15) (manufactured by RI04) is installed on each of the two rotating shafts arranged in parallel.
Several poems are written in six pieces in series. Each is designed to allow water to flow through it. Temperature-controlled water was passed through it as a coolant. The cooler was also equipped with a jacket for heat removal, which was used to remove reaction heat in the same way as the internal cooler.

The length from one tip of the stirring blade to the tip of the other blade separated by 180 degrees is 270 mm.

Screw conveyors were used for all the tubes connecting the polymerization reactor and the cooler and the tubes for extracting the produced copolymer from the hopper.

Formaldehyde (hereinafter referred to as FA) was prepared using the above device.1. A copolymerization reaction with 6-1-rioquimcan (hereinafter referred to as TOO) was carried out continuously.

Put about so kg of copolymer of FA and TOC into the device.
This was circulated at 6ooKy/h. Moisture content is 50~
80 ppm of gaseous FA at 6 K, g/h, gaseous Too at 480 g/h, toluene at 142 g/h, and gaseous boron trifluoride at 18.0 Bole/h (16), respectively. It was supplied from an inlet provided downstream of the hopper. The amount of cooling water entering the 7-polymerization reactor, the jacket of the cooler, and the disc-shaped cooling member was adjusted so as to maintain the copolymer kneader outlet temperature at 60°C. The resulting copolymer was withdrawn from the hopper overflow line, and the boron trifluoride was deactivated with gaseous ammonia. This continuous copolymerization reaction was carried out for 240 hours.

The intrinsic viscosity of the produced copolymer is 1.6. Base stability is 90%
The FA yield for one pass was 99. Copolymer TO
The C unit content was 2.0 mole%.

Example 2 Change the gaseous TOC supply rate to 390 r/h.

Bis(acetylacetone) copper 21.4μm 018/
Example 1 was repeated, except that liquid Too dissolved at a concentration of f/ was fed fresh at 9 oy/h.

The intrinsic viscosity of the resulting copolymer is 1.7. Base stability is 92%
The FA yield for one pass was 99. To of copolymer
The o unit content was 2.0 mole%.

Comparative example 1 Example 1 was repeated except that no toluene was fed.

The intrinsic viscosity of the resulting copolymer is 1.7. Base stability is 81%
The yield was 95%.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure and FIG. 6 are respectively a cross-sectional view along the line AA and line B-B in FIG. 1, and FIG. 4 is an enlarged cross-sectional view of the cooling member. 1... Two-shaft mixing agitator, 3... Mixing agitator blade. 4... Stirring shaft, 11... Cooler, 12... Stirring shaft, 15... Stirring blade, 16... Cooling member, 17...
Axis of rotation. Patent applicant: Ube Industries, Ltd. Figure 1 Figure 2 Figure 3 Figure 5 Figure 4 102-

Claims (1)

[Claims] Formaldehyde, a cyclic formal, an inert organic solvent of 0.1 to 20 parts by weight per 100 parts by weight of formaldehyde, and a formaldehyde copolymer recycled from the second step described below are continuously fed to a twin-shaft mixer. , copolymerizing the formaldehyde and cyclic formal in the presence of boron trifluoride. A first step of continuously discharging the formaldehyde copolymer, and a plurality of stirring shafts equipped with stirring blades are provided through the lower side wall, and the bottom wall is composed of a partial cylinder along the trajectory of the tip of the stirring blade. The formaldehyde copolymer from the first step is continuously supplied to a cooler in which a rotating shaft with a disc-shaped cooling member through which a cooling medium flows passes through the upper side wall. A method for producing a formaldehyde copolymer, which comprises a second step of cooling, extracting the copolymer corresponding to the amount produced, and returning the remainder to the first step.