JPH0542450B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing a formaldehyde copolymer, and more specifically, to a formaldehyde copolymer that has good stability in basic solvents and a low molding shrinkage rate. Concerning a method for producing a polymer.

(Prior art) JP-A-59-115318 discloses that formaldehyde, a cyclic formal including 1,3,6-trioxocane, and a specific amount of an inert organic solvent are continuously supplied to a twin-screw mixer, A method of copolymerizing the formaldehyde and a cyclic formal in the presence of boron trifluoride or an ether complex thereof is disclosed. According to this method, the copolymerization reaction can be carried out substantially in a gas phase state, and a formaldehyde copolymer having good stability in a basic solvent can be produced in good yield.

(Problems to be Solved by the Invention) When implementing the above method industrially, it is desired to further improve the stability of the resulting copolymer in a basic solvent. Furthermore, the copolymer obtained by the above method has a large shrinkage rate during molding, and it is desired to improve this point.

(Means for Solving the Problems) As a result of detailed study on the polymerization reactivity of formaldehyde and 1,3,6-trioxocane using boron trifluoride as a catalyst, the present inventors found that 1.
The polymerization rate of 3,6-trioxocane is significantly higher than that of formaldehyde, and when both are supplied to the reactor at the same time, 1,3,6-trioxocane is likely to be incorporated into the main chain of the copolymer in the form of blocks. was investigated for the first time. And 1,
It has been found that if 3,6-trioxocane is supplied in portions, a formaldehyde copolymer in which 1,3,6-trioxocane is randomly arranged in the main chain can be obtained. Furthermore, it has been unexpectedly found that by supplying 1,3,6-trioxocane in portions, the molding shrinkage rate of the resulting formaldehyde copolymer is improved.

According to the invention, formaldehyde, 1,3,
0.1 to 20 parts by weight of an inert organic solvent per 100 parts by weight of 6-trioxocane and formaldehyde are continuously fed to a twin-screw mixer, and the formaldehyde and 1,3 .

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.

The amount of 1,3,6-trioxocane used is 0.001 to 0.1 mol per mol of formaldehyde supplied,
In particular, it is preferably 0.01 to 0.04 mol.

1,3,6-trioxocane is fed in portions along the length of the twin-screw mixer. There is no particular restriction on the degree of divided supply, and it is possible to divide the supply into four or more points, but normally, dividing the supply into two or three points is sufficient to achieve the purpose of the present invention. . There are no particular restrictions on the locations where formaldehyde is supplied. For example, when supplying to two points, first 1, 3, and 3 are placed near the formaldehyde supply location.
A first amount of 6-trioxocane is fed and then unreacted formaldehyde is added in a twin-shaft mixer.
The remaining 1,3,6-trioxocane can be supplied at a location ranging from 10 to 50%. The amount of 1,3,6-trioxocane to be supplied in portions is such that the proportion to unreacted formaldehyde is approximately the same at each portion.

The two-shaft mixing agitator used in the present invention has two horizontal stirring shafts equipped with a large number of elliptical mixing blades housed in an external case, and when the stirring shafts are rotated, This device has a small gap between the surface of the mixing stirring blade and the inner wall of the case. Such a twin-screw mixer is commercially available as a KRC kneader from Kurimoto Iron Works Co., Ltd., for example.

Specific examples of inert organic solvents include pentane,
Examples include aliphatic hydrocarbons such as hexane and heptane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, aromatic hydrocarbons such as benzene, toluene and xylene, and halogenated products of these hydrocarbons. The amount of inert organic solvent used is 0.1 to 20 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of formaldehyde fed. 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 solvent. Even if the usage amount is larger than the upper limit,
The stability of the resulting copolymer in basic solvents is not increased, the resulting copolymer becomes wet and difficult to transport, and the cost of recovering the inert organic solvent increases.

Specific examples of boron trifluoride ether complexes include:
Examples include complexes of boron trifluoride and aliphatic ethers, such as dimethyl ether and diethyl ether. The amount of boron trifluoride or its ether complex used is usually 1 mol per mol of formaldehyde supplied.
×10 ⁻⁵ to 1×10 ⁻³ mol. When using a boron trifluoride ether complex that is liquid at room temperature, it is preferable to use the boron trifluoride ether complex in a gas phase in advance for the reaction.

The heat of the copolymerization reaction is usually removed using a separate external circulation cooler in the loop that circulates the copolymer. Cooling methods using this external circulation cooler include indirect cooling using a cooling jacket, direct cooling in which a low boiling point solvent is supplied into the cooler and its latent heat of vaporization is used, and a combination of both methods is adopted as appropriate. can do.

The copolymerization reaction temperature is usually 40 to 80°C. The space velocity of formaldehyde in a twin-screw mixer is usually 300 to 2000 h ^-1 .

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

Twin-shaft mixing stirrer 1 used as a polymerization reactor
consists of an external case 2 and two horizontal stirring shafts 4 equipped with a large number of elliptical mixing and stirring blades 3a and 3b.
It is composed of a and 4b. As shown in FIG. 2, when the stirring shafts 4a, 4b are rotated, the mixing stirring blades 3a, 3b have a small gap between the other surface and the inner wall of the outer case 2, usually 0.5 to 5 mm.
form a gap.

Inert organic solvents, boron trifluoride and formaldehyde are fed through tubes 11, 12 and 13, respectively. A first amount of 1,3,6-trioxocane is supplied via tube 14. The remaining amount of 1,3,6-trioxocane is supplied via line 15.
Formaldehyde copolymer from a cooler, not shown, is supplied through tube 16. The amount of copolymer fed through tube 15 varies depending on the heat of polymerization to be removed by the cooler, but is typically 50 to 200 times the weight of formaldehyde fed.

A copolymerization reaction between formaldehyde and 1,3,6-trioxocane is carried out in the twin-shaft mixer 1 in which the stirring shafts 4a, 4b and mixing blades 3a, 3b are driven by a motor (not shown). The produced copolymer is discharged through pipe 17 together with the circulating copolymer.

(Effects of the Invention) According to the present invention, as can be seen from the results of Examples described later, the stability in a basic medium is excellent, the molding shrinkage rate is small, and at the same time, the molding shrinkage rate in the longitudinal and lateral directions is low. A formaldehyde copolymer having a substantially uniform ratio can be obtained with good productivity.

(Example) Examples are shown below.

The intrinsic viscosity of formaldehyde copolymer is α-
The measurement was carried out at 60°C using p-chlorophenol containing 2% by weight of pinene as a solvent.

What is the base stability of formaldehyde copolymer?
At a copolymer concentration of 10% by weight in benzyl alcohol containing 1% by weight of tri-n-butylamine.
It means the recovery rate (%) of the copolymer after heat treatment at 160°C for 1 hour.

The molding shrinkage rate is 75mm x injection molded under the following conditions.
For a 75 mm x 3 mm sample, the shrinkage percentage in a direction parallel to the injection direction and the shrinkage percentage (%) in a direction perpendicular to the injection direction were determined on the 7th day after molding.

Molding machine: Screw type injection molding machine (4.5 oz) Mold temperature: 80℃ Resin temperature at nozzle: 205℃ Molding cycle: Injection time 30 seconds Cooling time 25 seconds Example 1 Kurimoto Iron Works Co., Ltd. as a polymerization reactor With manufactured hopper
Using KRC kneader #4, height 435mm, width 560mm with jacket part and internal cooler as cooler.
A twin-shaft mixing stirring type cooler with a length of 1150 mm and an internal volume of 200 mm was used.

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 equipment.
) and 1,3,6-trioxocane (hereinafter referred to as
A copolymerization reaction was carried out with TOC (referred to as TOC).

Approximately 50 kg of a copolymer of FA and TOC was placed in the device and circulated at 600 kg/h. Moisture content 50
~80ppm gaseous FA at 6Kg/h, gaseous TOC
288 g/h of toluene, 142 g/h of toluene, and 18 mmol/h of gaseous boron trifluoride in tubes 13, 14, 11, and 13, respectively, provided downstream of the hopper.
It was supplied from 12. In addition, 72g/g of gaseous TOC
h from tube 15. The temperature of the cooling water entering the jacket and internal cooling section of the cooler was adjusted so that the copolymer outlet temperature at the kneader was 60°C. The resulting copolymer was withdrawn from the hopper overflow line and contacted with gaseous ammonia to deactivate the boron trifluoride. This continuous copolymerization reaction was carried out for 240 hours.

The resulting copolymer has an intrinsic viscosity of 1.6, a base stability of 92%, a one-pass FA yield of 99%, and a TOC content of
It was 1.5 mol%.

Mold shrinkage rate is 1.9% in the machine direction and 2.0 in the perpendicular direction.
It was %.

Comparative example 1 Without TOC supply from inlet 15, inlet 1
The same procedure as in Example 1 was repeated, except that gaseous TOC was fed at 360 g/h from No. 4.

The intrinsic viscosity of the resulting copolymer was 1.6, the base stability was 87%, the 1-pass FA yield was 99%, and the TOC content was
It was 1.5 mol%.

The molding shrinkage rate is 1.5% in the machine direction and 2.8% in the perpendicular direction.
It was %.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a polymerization reactor that can be used in the present invention, and FIG. 2 is a sectional view taken along the line A--A in FIG. 2...Two-shaft mixing stirrer, 3...Mixing stirring blade, 4
...Stirring shaft.

Claims (1)

[Claims] 1 Formaldehyde, 1,3,6-trioxocane and 0.1 to 100 parts by weight of formaldehyde
20 parts by weight of an inert organic solvent was continuously fed into a twin-screw mixer, and the above formaldehyde and 1,3,
When copolymerizing with 6-trioxocane,
1. A method for producing a formaldehyde copolymer, which comprises supplying 1,3,6-trioxocane in portions in the longitudinal direction of a twin-screw mixer.