JPS59140215A - Production of formaldehyde copolymer - Google Patents

Abstract

PURPOSE:To obtain a formaldehyde copolymer excellent in stability in a basic medium in high yields, by continuously feeding a formaldehyde copolymer to a horizontal cooler and withdrawing the copolymer in an amount equal to that of the copolymer formed. CONSTITUTION:In step (a), a double-shaft blender is continuously fed with formaldehyde, 0.1-2pts.wt., based on formaldehyde, cyclic formal, and the formaldehyde copolymer recirculated from step (b). The formaldehyde is copolymerized with the cyclic formal in the presence of boron trifluoride, and the formed formaldehyde copolymer is continuously withdrawn. In step (b), the copolymer from step (a) is continuously fed to and cooled in a horizontal cooler provided with a plurality of rotary shafts which pass through the side wall of the cooler and each of which is fitted with a disk-form cooling member through which a cooling medium is passing and has an impeller on its outermost periphery, the wall of the bottom of the reactor being composed of a partial circle along the locus of the tip of the impeller, and the upper wall being arc-shaped. The copolymer in an amount equal to that of the copolymer formed is withdrawn and the remaining portion is returned to step (a).

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 molecular weight of 9 and low stability in a basic medium, as seen from the results of the examples in the above publication, and cannot be put to practical use.

Japanese Patent Publication No. 44-8'70 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, making smooth operation 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 a twin-screw mixer, the activity of boron trifluoride or its ether complex used as a catalyst is low, and productivity is low. It's small.

A problem arose that the resulting copolymer had poor stability in basic media. Further, in the copolymerization of formaldehyde and cyclic formal, a large amount of heat of polymerization is generated, but a twin-screw mixer cannot completely remove the heat of polymerization because the heat transfer area is small.

In order to avoid this, 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 1 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 is.

Formaldehyde, 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-shaft mixer, and boron trifluoride is The above formaldehyde and cyclic formal are copolymerized in the presence of

The first step is to continuously discharge the formaldehyde copolymer, and a disk-shaped cooling member through which a cooling medium flows is attached. A plurality of rotating shafts are provided passing through the side wall, and a plurality of rotating shafts are provided at the outermost periphery of the cooling member. A horizontal cooler is equipped with a stirring blade, the bottom wall of the first reactor is formed by a partial cylinder along the locus of the tip of the stirring blade, and the earthen wall is formed in an arc shape. This is a method for producing a formaldehyde copolymer, which comprises a second step in which the formaldehyde copolymer from the step is continuously supplied and cooled, the copolymer corresponding to the amount produced is extracted, and the remainder is returned to the first step.

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.

The twin-shaft mixing stirrer 1 used as the first step polymerization reactor is composed of an outer case 2 and two horizontal stirring shafts 4.5 to which a number of elliptical mixing blades 3 are attached. As shown in FIG. 2, when the stirring shaft 4°5 is rotated, there is a slight gap between the mixing stirring blades 3 and the other surface and the inner wall of the outer case 2.

Usually, a gap of 0.5 to 5 mm is formed. Such a twin-shaft mixer 1 is 9, for example, K RC from Kurimoto Iron Works Co., Ltd.
, is commercially available as a kneader.

Formaldehyde, cyclic formal, inert organic solvent and boron trifluoride are fed through tubes 30.degree. 31.32 and 33, respectively. The formaldehyde copolymer (hereinafter simply referred to as "copolymer") from the second step is transferred to tube 3.
Supplied from 4.

The moisture content of formaldehyde is preferably 0.1% by weight or less, particularly 0.01% by 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 (in both the above formulas R1, 1:(
2゜R3 and R4 are hydrogen, alkyl group,
It represents an allyl group and a cycloalkyl group, 9m represents an integer of 1 to 3, and n represents an integer of 2 to 6. ) is used. Specific examples include ethylene oxide, propylene oxide, epichlorohydrin, epibromohydrin, butene-1-oxide, l,3-ptadiene-1-oxide, styrene oxide, a-methylstyrene oxide, oxetane, tetrahydrofuran, 1, 3- Geoquinran.

4-phenyl-1,3-dioquinrane, 2-methyl-1
, 3-dioxolane, 2-phenyl-1,3-dioxolane, l,3-dioquinpane, 2-butyl-1,3-dioxopane, 1,3.6-)dioquincane.

1.3.5-) Lioxopane and polyethylene glycol formal are mentioned. The amount of cyclic formal used is 0.001 to 0.001 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 hexane.

Aliphatic hydrocarbons such as heptane, cyclohexane.

Alicyclic hydrocarbons such as cyclopentane, benzene.

Examples include aromatic hydrocarbons such as toluene and xylene, and halides of these hydrocarbons. It is preferable that the inert organic solvent is subjected to the reaction in a gaseous state. The amount of inert organic solvent used is per 100 parts by weight of formaldehyde supplied,
The amount is 0.1 to 20 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.

In addition, the stability of the resulting copolymer in a basic medium becomes low. 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 be increased.

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 10-5 to 1 per mole of formaldehyde supplied.
xlO-3 mol. 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 9, for example,
C1-'i'073 publication, 42-958 publication, 4-2-7629 publication, 42-22068 publication,
Publication No. 42-19340.

The chelate compounds described in Japanese Patent No. 49-35839 are used. Typically, Cu, Co, Fe.

Examples include chelate compounds having a metal such as Ni or V as a central atom and a ligand such as β-diketones, aromatic oxydialdehydes, or condensates of aromatic oxidialdehydes and diamines. The amount of metal chelate compound used is
1 mole of boron trifluoride roars.

It is preferably 0.5 mol or less, particularly 0.05 to 0.5 mol. By using a metal chelate compound in combination, the stability of the produced copolymer in a basic medium is further 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 34.

Although it varies depending on the polymerization heat to be removed in the second step, 7
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 stirring shafts 4, 5 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 is usually 30
0 to 200, Oh''-1, and the average residence time of the copolymer is usually 5 to 30 seconds.

The product copolymer is discharged through tube 35 together with the circulating copolymer.

The second step cooler 11 includes a jacket 1 through which a cooling medium flows.
2 is installed. The two rotating shafts 13 and 14 are
It is provided to penetrate both side walls of the cooler 11. Preferably, the rotation axes 13, 14 are arranged parallel to each other. What is the spacing between the rotation axes 13 and 14?

It is preferable that the trajectories (rotating circles) of the tips of stirring blades 15, which will be described later, be close to each other or overlap nine times. still.

Although three or more rotating shafts can be provided, there is no significant difference in mixing performance, so two shafts are practically sufficient.

Nine disc-shaped cooling members 16, 17 are attached to the rotating shafts 13, 14. Rotating shaft 13.14 and cooling member 1
The inside of 6.17 has a structure in which a cooling medium flows, as shown in FIG. 4, for example. Rotating axis 13.14
A rotary joint 1B is attached to one end of the rotary joint 1B for supplying and discharging a cooling medium to the rotary shaft 13.14 and the cooling members 16.1' and 16.1'. The size and number of cooling members 16 and 17 can be appropriately determined by those skilled in the art, taking into consideration the amount of polymerization heat to be removed.

Cooling member 16, in contact with the outermost periphery of '17, stirring blade 15
is installed. There are no particular restrictions on the shape of the stirring blades 15, but in order to form a circulating flow of the powdery copolymer within the cooler 11, flat stirring blades are attached to the rotating shaft 13.
It is preferable to make it parallel to 14. However, for the purpose of promoting movement of the particulate copolymer in the direction of the rotation axis of the cooler 11, the stirring blades 15 may be inclined with respect to the axial direction, or parallel blades and inclined blades may be combined.

A plurality of stirring blades 15 can be arranged symmetrically, and three or four blades may also be employed, but two blades are usually sufficient. The stirring blades 15 are attached so that both blades do not come into contact with each other due to rotation. The width of the stirring blade 5 with respect to the rotation radius of the stirring blade 15 is larger, the cooling member 16
．． Since the 1'70 radius is small and the heat transfer area is reduced, it is desirable that it be small as long as a circulating flow of the particulate copolymer is formed.

The bottom wall of the cooler 11 is formed of a partial cylinder along the trajectory of the tip of the stirring blade 15. The limit for partial cylinders is 1/2
Up to the cylinder. In other words, if the tips of the stirring blades 15 are located far apart, there is a
It is preferable to provide a chevron-shaped connection portion to prevent powder from stagnation.

The gap between the bottom wall of the cooler 11 and the tip of the stirring blade 15 is preferably as small as possible, and is generally 10 mπ or less.

The earthen wall of the cooler 11 is formed in an arc shape.

In particular, it is preferable that the upper part of the seventh cooler 11 is formed by a partial cylinder whose diameter is the distance between both reactor walls in a horizontal line passing through the center of one rotation axis 13,14.

A weir 19 is provided on one side wall of the cooler 11.
9, a copolymer extraction nozzle 20 is provided. Note that the copolymer extracting device is not limited to what is shown in the drawings, but for example.

At the bottom of the cooler 11, an extraction nozzle passing through the jacket 2 can also be provided.

Although the length of the cooler IY' in the axial direction is arbitrary, it is usually 1 to 7 times, particularly 5 to 5 times, the diameter of the 150-rotation circle of the stirring blade. The cooler 11 is preferably installed horizontally, but for the purpose of promoting movement of the powdery copolymer in the axial direction, it can also be installed at an inclination of no more than 10' from the horizontal.

The copolymer from the first step is fed through tube 35. The rotating shafts 13 and 14 are rotated at a constant speed by a drive device (not shown). The rotating shafts 13 and 14 may be rotated in any direction, but from the viewpoint of uniformity of stirring, it is preferable to rotate both shafts in opposite directions.
clockwise.

It is particularly preferred to rotate the rotating shaft 14 counterclockwise. The rotational speed of the rotating shafts 13 and 14 is preferably 1 to 5 m/sec as the tip speed of the stirring blade 5.

The amount of granular 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 particulate copolymer is stirred up by the stirring blades 15 to form a forced circulation flow.

The heat of polymerization is the refrigerant flowing inside the jacket 12.

Cooling member from rotary joint 18: L6. l'i
' is removed by the refrigerant supplied to the In the present invention, the granular copolymer violently collides with the entire cooling member 16, 17, and the heat transfer surface itself rotates, thereby
The sliding force of the powder increases, and the heat transfer surface uniformly contacts the fluid. Therefore, there is little adhesion of the powdery 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 particulate copolymer is discharged through tube 34.

An amount of copolymer commensurate with the product copolymer is withdrawn as product from tube 36, and the remaining copolymer is returned to the first step through tube 34.

In the present invention, the transfer tube 34°35 of the powdery copolymer
It is preferable to use a forced transfer pipe such as a screw conveyor as 36 and 36.

Next, examples will be shown.

The intrinsic viscosity of the copolymer was measured at 60° C. using p-chlorophenol containing 2% by weight of α-pinene as a solvent. The base stability of a copolymer is the recovery rate (%) of a copolymer when it is heat-treated at 160° C. for 1 hour at a copolymer concentration of 10% by weight in benzyl alcohol containing 1% by weight of tri-n-butylamine.

Example 1 KR with hopper manufactured by Kurimoto Iron Works Co., Ltd. as a polymerization reactor
C kneader #4 was used, and the cooler had the shape shown in FIGS. 1, 3, and 4.

Height: 4.35 mJI+, width: 560 mm, length: 115 mm
A cooler made of 5US304 and having an internal volume of 200 tons was used. The cooler has a cooling member (outer diameter 20 mm) shown in Figure 4.
Two rotating shafts each having 10 pieces of (0M, 5US304) attached at an interval of 95 degrees are installed in parallel. Two stirring blades are attached to the outer periphery of each cooling member at opposing positions. A screw conveyor was 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) using the above equipment
and 1.3.6-) dioquincan [hereinafter referred to as To.

The copolymerization reaction was carried out continuously.

A copolymer of FA and T'OC of approximately 50 to 2 liters was placed in the apparatus and circulated at 600 to 9/h. Moisture content 50
~80 ppm gaseous FA at 6 KFI/h, gaseous Too at 4802/h, and toluene at 142 g/h.
gaseous boron trifluoride at 18 mmo:Le/h
in.

Each was supplied from an inlet provided downstream of the hopper. The amount of cooling water entering the cooler jacket and cooling member was adjusted to maintain the copolymer kneader exit temperature at 60°C. The resulting copolymer was drawn off through the overflow line of the hopper and contacted with gaseous ammonia to deactivate the boron trifluoride. This continuous copolymerization reaction was carried out for 240 hours.

The intrinsic viscosity of the resulting copolymer is 16. Base stability is 90%
, l pass FA yield is 99%, Toe content is 2.0 m
It was an ole article.

Example 2 Change the supply amount of gaseous Too to 59oy/h.

21.4 μm o l of bis(acetylacetone) copper
90f/h of liquid Too dissolved at a concentration of e/f
Example 1 was repeated except that a fresh supply was made.

The intrinsic viscosity of the resulting copolymer is 1.7. Base stability is 92
1-pass FA yield is 99%, ToC content is 2.0
It was 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
%, 1 pass FA yield was 95%.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
3 are a sectional view taken along the line AA and BB in FIG. 1, respectively, and FIG. 4 is an enlarged sectional view of the cooling member. 1... Twin-shaft mixing agitator, 3... Mixing stirring blade, 4...
・Stirring shaft, Nido... Cooler, 13.14... Rotating shaft,
U5... Stirring blade, 16.1'7... Cooling member, 19
...weir. Patent applicant: Ube Industries, Ltd. Figure 2 Figure 3 Figure 4 Figure 5

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 rotating shafts to which a disk-shaped cooling member through which a cooling medium flows are installed through the side wall, The bottom wall of the 91 reactor is equipped with a stirring blade, and the bottom wall of the reactor is made up of a partial cylinder along the locus of the tip of the stirring blade. A method for producing a formaldehyde copolymer, which comprises a second step of continuously supplying and cooling formaldehyde copolymer, extracting the copolymer corresponding to the amount produced, and returning the remainder to the first step.