JPH04246423A - Method for preventing resin from blocking in reaction tank - Google Patents

Abstract

PURPOSE:To prevent a resin from blocking in a reaction tank and facilitate the maintenance and control of the reaction tank, such as cleaning, to thereby improve the production efficiency by preventing the loss of products in the synthesis of a resin which is apt to block in the reaction tank, such as polyvinyl butyral resin. CONSTITUTION:Water is scattered on the neighboring part of the liq. interface and the inner wall face 11 of a reaction tank 1 above the liq. interface and a stirring shaft 21 of a stirrer 2 to prevent a cured product of the resin from depositing on the inner wall face 11 in the tank and the stirring shaft 21.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for preventing resins from forming blocks in a reaction tank when synthesizing resins that tend to coalesce, such as polyvinyl butyral.

0002

2. Description of the Related Art Generally, synthetic resins are obtained by charging raw materials into a reaction tank and polymerizing or condensing the raw materials under the action of a catalyst or the like. For example, by adding a plasticizer, polyvinyl butyral (hereinafter referred to as "
PVB) can be obtained by placing polyvinyl alcohol and butyraldehyde in a reaction tank containing water in the presence of an acid catalyst and reacting (condensation reaction) with stirring.

0003

[Problems to be Solved by the Invention] When synthesizing a resin as described above, normally, in order to keep the temperature of the reaction solution constant during the reaction, a jacket is provided surrounding the reaction tank to keep the temperature constant. heated to a certain temperature. Therefore, the tank wall above the liquid interface of the reaction tank, the stirring shaft of the stirrer, etc. are dry, and when the resin slurry scattered from the liquid interface hits these, it instantly dries and hardens. Then, the hardened adhesive resin overlaps many layers at the interface to form a huge film-like deposit. This deposit may peel off due to its own weight or the liquid flow caused by stirring and fall into the reaction solution, but in the case of resins that tend to coalesce, such as PVB, this fallen deposit may be stirred in the liquid. While it is being used, it also absorbs resin and becomes a huge block. Therefore, when the reaction is finished and the slurry-like resin is extracted from the lower outlet provided at the bottom of the reaction tank, the block clogs the lower outlet, which not only takes time but also requires extra time such as backwashing. work must also be done. In particular, huge blocks do not fall out of the lower extraction port even after backwashing, so they have to be manually scraped up and removed from the upper manhole of the reaction tank, which is time-consuming and dangerous, and also reduces product yield. It's bad. In addition, deposits on the tank walls are cleaned using high-pressure water or a spatula after each reaction, but cleaning may damage the tank walls and shorten the life of the tank. Since the smoothness is impaired, there is a problem that adhesion is promoted during the next reaction. Furthermore, if the hardening is severe, a person has to enter the tank to remove it, which is both time-consuming and dangerous. In view of these circumstances, this invention provides a method for preventing resin from forming blocks in a reaction tank, which can improve production efficiency by improving product recovery rate, reducing tank cleaning work, block removal work, etc. is intended to provide.

0004

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention aims to reduce the amount of resin in the reaction solution when synthesizing a desired resin by reacting raw materials in a reaction tank. This is a method to prevent blocking, and during the reaction, water is sprinkled on the inner wall surface of the reaction tank near the liquid interface and above it, as well as on the stirring shaft of the stirrer, to prevent the adhesion of resin in the reaction liquid that is scattered due to stirring, etc. The gist of this paper is a method for preventing resin blocking in a reaction tank, which is characterized by:

[0005]

[Operation] According to the above structure, by spraying water on the tank inner wall surface near the liquid interface of the reaction tank and above it, and on the stirring shaft of the stirrer during the reaction, water is scattered onto the inner wall surface of the tank and the stirring shaft of the stirrer. The resin slurry can be washed away and returned to the tank before the resin hardens and adheres.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to the drawings showing embodiments thereof. To carry out the method of preventing resin blocking in a reaction tank according to the present invention, for example, an apparatus as shown in FIG. 1 can be used, although there is no particular limitation. As shown in the figure, this device includes a reaction tank 1 covered with a jacket 6, and a stirring blade 2, a water sprinkling ring 7, and a baffle 3 inside the reaction tank 1. The stirring blade 2 is configured to stir the reaction liquid inside the reaction tank 1 by rotating the stirring shaft 21, and is preferably a Faudler blade, although it is not particularly limited. The water sprinkling ring 7 is configured to spray water onto the tank inner wall surface 11 in the vicinity of the reaction liquid interface and above the reaction liquid interface and on the stirring shaft 21 of the stirring blade 2 by injecting water from the water injection port 8 . In the figure, 4 is an upper manhole, and 5 is a lower outlet. Next, examples using this device will be described together with comparative examples.

(Example 1) Raw materials for synthesizing PVB resin are charged into a reaction tank 1, and steam (7 kgG/cm2, 140°C) is supplied to a heating jacket 6 while stirring by rotating the stirring blade 2 at a rotational speed of 100 rpm. The temperature inside the reaction tank 1 was raised to 70° C., and then left for 5 hours with stirring. Further, during the reaction, water at 20° C. was continuously sprayed from the water sprinkling ring 7 onto the tank inner wall surface 11 and the stirring shaft 21. The total amount of water sprinkled is 5% of the total amount of liquid in reaction tank 1 (3.5 l/min)
Met. When the PVB resin slurry in the reaction tank 1 obtained after 5 hours was extracted from the lower extraction port 5, the amount of blocks was 1.5% of the total amount of resin, and the blocks were generally small. I was able to extract everything successfully. Further, there was almost no resin adhering to the tank inner wall surface 11 and stirring shaft 21 in the vicinity of the liquid interface and above it, and all the resin adhering to the tank wall after extraction was washed away by sprinkling water from the water sprinkling ring 7. The adhesion amount was 1.3% of the total resin amount.

(Comparative Example 1) A PVB resin slurry was obtained in the same manner as in Example 1 except that water was not sprinkled. Obtained P
When the VB resin slurry was extracted from the lower outlet 5, there were many blocks with a diameter of about 10 cm, and during the extraction process, the lower outlet 5 was blocked many times, requiring backwashing and other work. It took time. Further, there are blocks whose diameter is larger than the diameter of the lower extraction port 5, and such huge blocks have to be manually scraped out from the upper manhole 4. Note that the block amount was 9.1% of the total resin amount. Moreover, the resin deposits on the tank inner wall surface 11 near the liquid interface are 1 to 3 cm thick and 40 cm wide.
cm, and was adhered in a ring shape all around the circumference, and although water was applied from the water sprinkling ring 7, it could not be removed. The amount of adhesion was 4.2% of the total amount of resin.

(Example 2) PVA (polyvinyl alcohol) with a concentration of 10% was heated to 80 to 90°C to completely dissolve it, and this PVA solution was charged into a reaction tank (polymerization tank) 7, and vinyl acetate monomer and catalyst is added dropwise, and the reaction tank 7 is heated by passing steam through the jacket 6 to raise the temperature of the reaction solution to 70 to 80° C. at which polymerization starts. Then, at that temperature, the stirring blade 2 was rotated at a rotational speed of 45 rpm while water was being sprinkled from the water sprinkling ring 7, and stirring was continued for 6 to 8 hours to emulsion polymerize the polyvinyl acetate. When the obtained polymer slurry was extracted from the lower extraction port 5, there was almost no deposit on the tank inner wall surface 11 and stirring shaft 21 in the vicinity of the liquid interface and above it.
There were only spots of deposits here and there. Additionally, all deposits could be washed away by sprinkling water from the upper manhole. The amount of adhesion was 0.6%.

(Comparative Example 2) A polymer was obtained in the same manner as in Example 2 except that water was not sprinkled. On the inner wall surface 11 of the tank in the vicinity of the liquid interface, deposits are attached in a ring shape around the entire circumference with a thickness of 1 to 3 cm and a width of 30 to 40 cm.
After pulling it out, water was sprinkled from the upper manhole 4, but it could not be removed. This amount of adhesion was 5.1% of the total amount of resin.

[0011]

[Effects of the Invention] The method for preventing resin blocking in a reaction tank according to the present invention is constructed as described above, and prevents resin from adhering to the inner wall surface of the tank and the stirring shaft. Blocking of the resin can be prevented. Therefore, product loss is reduced and
Extraction work can now be done easily and in a short time.
Productivity can be improved. In addition, there is no deposit on the inner wall of the tank, and the inside of the tank can be cleaned by cleaning with water only, so there is no need to clean the tank wall with a spatula or the like as in the past, which could damage the coating on the inner wall of the tank. It disappears. therefore,
The life of the tank itself can also be extended.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing an example of an apparatus used to carry out the method for preventing resin blocking in a reaction tank according to the present invention.

[Explanation of symbols]

1 Reaction tank 7. Watering ring 11 Tank inner wall surface 21 Stirring shaft

Claims (1)

[Claims] [Claim 1] A method for preventing resin blocking in a reaction solution when a desired resin is synthesized by reacting raw materials in a reaction tank, the method comprising: A method for preventing resin from forming blocks in a reaction tank, which comprises spraying water on the upper inner wall surface of the reaction tank and the stirring shaft of a stirrer to prevent adhesion of resin in the reaction liquid scattered by stirring or the like.