JPH0445107A - Production of acrylonitrile-based polymer - Google Patents

Abstract

PURPOSE:To obtain the subject polymer, excellent in productivity and useful as fiber, etc., by polymerizing a specific acrylonitrile-based polymer, washing the resultant polymer, dehydrating the washed polymer, adding a prescribed amount of an anionic surfactant to the resultant wet polymer, forming the prepared mixture into the shape of pellets, then drying and pulverizing the formed pellets. CONSTITUTION:An acrylonitrile (AN)-based polymer (e.g. acrylic acid is used as a monomer other than the AN) containing 40-97% AN is polymerized by an aqueous suspension polymerization method, washed and dehydrated to provide a wet polymer. An anionic surfactant (e.g. a sodium alkylbenzenesulfonate) in an amount of 0.005-0.1% is then added thereto and the resultant polymer is formed into the shape of pellets, which are subsequently dried and pulverized to afford the objective polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a novel acrylonitrile polymer.

[Problems to be solved by conventional techniques and inventions] Acrylic fibers have excellent texture and color clarity, and can be used for curtains,
It is widely used in interior applications such as carpets and clothing such as sweaters and jerseys. This acrylic fiber is manufactured by spinning a polymer containing Acrylic 110 nitrile, and the process of manufacturing the acrylonitrile polymer is essential for Acrylic 111M.

Aqueous suspension polymerization, solution polymerization, emulsion polymerization, and other methods have been industrialized to produce acrylonitrile polymers, but aqueous suspension polymerization is superior in terms of high productivity and ease of handling the polymer. It is a widely used manufacturing method.

The aqueous suspension polymerization process consists of polymerization, washing and dehydration, drying, and recovery of seven polymers, and post-processes other than polymerization are also important from an industrial perspective. In particular, the drying process consumes a large amount of thermal energy and therefore accounts for a high proportion of the production cost of the polymer, so it is a process that should be particularly focused on in order to improve production efficiency. Belt dryers, fluidized fluid dryers, hot air dryers, etc. are used to dry wet acrylonitrile polymers, but belt dryers are advantageously used because they have good drying efficiency and less risk of dust explosion. .

When drying a wet polymer using a belt dryer, it is necessary to mold the polymer into a Kmm pellet shape in order to improve the permeability of hot air and increase the drying efficiency. This pellet molding method is generally used because extrusion molding is easy to handle.

In order to reduce the manufacturing cost of acrylonitrile polymers, it is necessary to reduce the water content of the wet polymer pellets. However, when the water content of the wet polymer is reduced, moldability becomes difficult, and even if molding is possible, the pellet strength after drying decreases, and some of it becomes powder during drying and leaks out of the drying net, reducing the polymer yield. becomes. For this reason, methods have been adopted in which wet polymers are given appropriate moisture and then molded, which increases the drying load in the production of acrylonitrile polymers.

[Means to solve the problem]

The gist of the present invention is to polymerize an acrylonitrile-based polymer containing 40 to 974 acrylonitrile by an aqueous suspension polymerization method, wash and dehydrate the resulting wet polymer, mold it into a pellet shape, dry it, and crush it to form an acrylonitrile-based polymer. When producing the combined powder, an acrylonitrile-based polymer is produced by adding a 7-ionic surfactant to the wet polymer at α005 to [114].

The anionic surfactants used in the present invention are commonly used, such as sodium alkylbenzene sulfonate and sodium alkyl ester sulfonate, and are not defined in terms of percentage. If the addition f of anionic surfactant is less than the tlQO5 width, no effective effect can be obtained, and α1
If it exceeds 4, the wet polymer becomes viscous and cannot be molded.

The anionic surfactant can be added by kneading with the wet polymer, or by adding excess surfactant into the acrylonitrile polymer slurry, stirring and mixing, and then dehydrating to form a wet polymer. However, the latter method is superior due to the ease of the process.

The acrylonitrile polymer used in the present invention is an acrylonitrile polymer comprising acrylonitrile 40 to 974 and other monomers.

Other monomers include acrylic acid, methacrylic acid and its esters, vinyl acetate, acrylamide, vinyl chloride, vinyl bromide, vinylidene chloride, styrene, allylsulfonic acid, methacrylic acid, benzenesulfone and hisobottle. etc.

The aqueous suspension polymerization method of the present invention is a polymerization method using water as a medium, and it does not matter whether it is a continuous or patch polymerization method. The present invention is also effective when some surfactant is added for purposes other than emulsifying and dispersing the polymer suspension.

The ratio of water to monomers such as acrylonitrile (hereinafter referred to as water/
Although the monomer ratio (referred to as monomer ratio) is not particularly limited, if the water/monomer ratio is lowered, the water content of the wet polymer can be lowered even with the same dehydration method, and the effects of the present invention can be utilized more effectively. can.

The results of the present invention can be obtained without any problem if the polymerization conditions other than water/monomerization are generally set conditions.

The polymer suspension obtained after the polymerization reaction is dehydrated and washed. Dehydration and cleaning methods include continuous rotary cylindrical filters, centrifugal dehydrators, etc., and both can be effectively used in the present invention, but continuous rotary cylindrical filtration machines that can be operated continuously are industrially superior. There is.

In order to reduce the water content of the wet polymer, it is also possible to dehydrate it by pressing or the like at the final stage of the filtration process.

The lower the water content of the obtained wet polymer, the more the drying load can be reduced; however, if the water content is lowered too much, it will not be possible to form it into a pellet shape, which will conversely cause a decrease in drying efficiency. Although the specific water content varies depending on the shape of the polymer particles produced depending on the polymerization method, it is generally from 100 to 6,001. If the water content is less than 100, the above-mentioned problems will occur, but by using the present invention, the moldable water content can be lowered to 80 or more. Moreover, the obtained pellet retains excellent strength even after drying, and can be dried without becoming pulverized.

The dried acrylonitrile-based polymer pellet is crushed to form Acrylic II! used for maintenance or other purposes.

〔Example〕

The present invention will be specifically explained below using examples.

A. "Part J" means "part by weight" and "彊" means "weight 4."

The strength of the dried pellet was measured using the following method.

Place the quantified dry pellet (Wf) on a 10-mesh sieve, shake it for 10 seconds with a shaker, then measure the amount of dry polymer (vr, t) remaining on the sieve, and calculate the residual rate from the following formula. . The higher the residual rate, the higher the strength of the dried pellet.

Remaining rate (regret) = -x 1o.

Example 1 Ammonium persulfate, hydrogen sulfite (IJ) in the ratio of 91 parts acrylonitrile, 9 parts vinyl acetate, and 200 parts water.
Polymerization was carried out continuously for an average residence time of 95 minutes at a polymerization reaction temperature of 55° C. using aluminum as a catalyst and at a pH of 50 in the reaction system with sulfuric acid.

The obtained polymer suspension was washed with a continuous rotary cylindrical filter, and then a wet polymer having a water content of 754 was obtained with a centrifugal dehydrator. A solution prepared by dispersing a surfactant shown in Table 1 of α024 in water was added to this wet polymer and mixed to obtain a water content of 85.
A wet polymer of No. 4 was prepared.

This wet polymer has a thickness of 2 mm with 200 pores of 5 mm in diameter.
A pellet was extruded from a 0-perforated plate. This pellet was dried at 70° C. to a moisture content of 14 or less, and the residual percentage of the pellet after drying was measured. The results are shown in Table 1.

Table Example 2 A polymerization reaction using ammonium persulfate and sodium hydrogen sulfite as catalysts in a ratio of 91 parts of acrylonitrile, 9 parts of vinyl acetate, and 200 parts of water. Polymerization was carried out continuously with a residence time of 95 minutes.

The obtained polymer suspension was washed with a continuous rotating cylindrical filter, and then a wet polymer with a water content of 70 was obtained using a centrifugal dehydrator. A liquid dispersed in water was added to this wet polymer so that the amount of surfactant added to the polymer was 1024, and a wet polymer having the water content shown in Table 2 was prepared.

This wet temperature polymer is 1! A pellet was extruded from a 20-thick perforated plate having 200 holes with a diameter of 5 m. This pellet was dried at 70"C to a moisture content of 14 or less, and the residual percentage of the pellet after drying was measured.

Table 2 It can be seen that the anionic surfactant has a high pellet retention rate in the case where the water content is low.

Example 3 91 parts of acrylonitrile, 9 parts of vinyl acetate, 200 parts of water, ammonium persulfate, hydrogen sulfite) I
Polymerization was carried out continuously using Jum as a catalyst, at a polymerization reaction temperature of 55° C., at a pHAO of sulfuric acid in the reaction system, for an average residence time of 95 minutes.

The obtained polymer suspension was washed with a continuous rotary cylindrical filter, and then a wet polymer having a water content of 704 was obtained with a centrifugal dehydrator. A solution prepared by dispersing a surfactant in water was mixed with this wet polymer so that the water content was 854, and a wet polymer with sodium alkylbenzenesulfonate added thereto as shown in Table 3 was prepared. .

This wet polymer has a thickness of 2 mm with 200 pores of 5 mm in diameter.
It is extruded from a 0■ perforated plate and molded into a pellet. This pellet was dried at 70° C. to a moisture content of 1 or less, and the residual percentage of the pellet after drying was measured. The results are shown in Table 3.

Table Example 4 A polymerization reaction using 56 parts of acrylonitrile, 41 parts of vinylidene chloride, 3 parts of sodium metaallylsulfonate, and 200 parts of water using ammonium persulfate and sodium bisulfite as catalysts at a temperature of 55°C and sulfuric acid in the reaction system. pH
! As LO, polymerization was carried out continuously with an average residence time of 2009 r-.

The obtained polymer suspension was washed with a continuous rotary cylindrical filter, and then a wet polymer with a water content of 75 or more was obtained with a centrifugal dehydrator.

Table 1 of [LL] 24 for this wet polymer
A wet polymer having a water content of 854 was prepared by adding and mixing a solution in which the surfactant shown in Figure 1 was dispersed in water.

This wet polymer has a thickness of 2 mm with 200 pores of 5 m in diameter.
A pellet was extruded from a perforated plate having a diameter of 0.0 mm. This pellet was dried at 70° C. to a moisture content of 14 or less, and the residual percentage of the pellet after drying was measured.

Table 4 [Effects of the Invention] The present invention provides a method for making the aqueous suspension continuous force combination method more efficient, which is the most excellent method for producing acrylonitrile polymers used as raw materials for acrylic fibers. By using a large-scale method, the drying load can be reduced, the manufacturing cost of acrylonitrile polymer can be lowered, and acrylic fibers can be supplied at low cost.

Claims (1)

[Claims] An acrylonitrile polymer containing 40 to 97% acrylonitrile is polymerized by an aqueous suspension polymerization method, and the wet polymer obtained by washing and dehydration is molded into pellets, dried, and crushed to produce an acrylonitrile polymer powder. At this time, an anionic surfactant is added to the wet polymer at a ratio of 0.
A method for producing an acrylonitrile polymer, characterized in that 0.005 to 0.14 is added.