JPS6047007A - Suspension polymerization of venyl chloride monomer - Google Patents

Abstract

PURPOSE:To produce a high-quality (low fish eye content) vinyl chloride polymer within a short time at a high rate of production, by uniformly mixing a monomer with a polymerization initiator, a dispersant, etc., at a temperature <=40 deg.C and polymerizing the mixture under agitation by adding an aqueous heating medium thereto. CONSTITUTION:A mixture is formed by mixing a vinyl chloride monomer with a polymerization initiator (e.g., diisopropyl oxydicarbonate), a dispersant (e.g., methylcellulose) and, optionally, additives at a temperature <=40 deg.C (the dispersant may be added in the form of an aqueous solution, but the volume ratio of a monomer pahse (oil phase) to a water phase must have a value falling within the range (defined by the formula). The formed mixture is suspension-polymerized under agitation by adding thereto an aqueous heating medium in such a manner that the temperature of the polymerization system after the addition is brought to a predetermined value. The temperature of the aqueous heating medium is set in consideration of heat dissipation, heat of polymerization during feeding, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved suspension polymerization method for vinyl chloride monomers.

Solicit polymerization of vinyl chloride monomers is usually carried out in a batch process, in which a ζ diaqueous medium, a dispersant (suspending agent), a polymerization initiator, and a vinyl chloride monomer are charged in a polymerization vessel, and then the necessary The common method is to add additives and then vortex to carry out the polymerization reaction.However, in order to improve productivity (shorten the time required for one patch of polymerization), In addition to shortening the reaction time, it is also necessary to shorten the temperature rise time.Especially in large-sized polymerization vessels and polymerization vessels with condensers, the heating capacity of the jacket etc. is relatively small compared to the internal volume. [Two smaller and therefore more effective heating methods need to be developed.

As a result of intensive research to overcome the above-mentioned problems, the present inventors have found that after uniformly mixing a vinyl chloride-based medium, a polymerization initiator, a dispersant, and other additives that may be added as necessary at a temperature of 40°C or lower, By charging the homogeneously mixed system while stirring the heated aqueous medium, we were able to eliminate the heating time and successfully obtain a vinyl chloride polymer with less heat retention.

Furthermore, when uniformly mixing the vinyl chloride monosorbent, the polymerization initiator, and the dispersant, various additives 7J1. It has been found that by adding agent I, the quality of the vinyl chloride polymer obtained is significantly improved compared to the commonly used additive addition method (1) (2). Additives such as polymerization degree regulators, chain transfer agents, singling inhibitors, gelation improvers, band prevention agents, and pH adjusters are used to improve the quality of coalescence or to impart new properties. In the polymerization method, these additives are added to the polymerization system after the vinyl chloride monocular body or the aqueous medium is dissolved, or after the vinyl chloride monocular body and the aqueous medium are charged.However, in this method, the additives are Within the polymerization system (long pre-stirring is required to achieve bi-dispersion, or the additives are not fully dispersed, resulting in variations in quality, making it impossible for the additives themselves to fully demonstrate their effects.

On the other hand, there is a method in which the additives are also mixed homogeneously when the vinyl chloride monomer, polymerization initiator, and dispersant are homogeneously mixed, and then a heated aqueous medium is added to this homogeneously mixed system. For example, the additive 1 JUJ agent is bidispersed in the complete 5 polymerization system,
The quality of the vinyl chloride polymer obtained is significantly improved.

According to the method of the present invention, the process from charging to completion of polymerization is 1.
Patch (double time can be greatly reduced (2),
Moreover, it has the advantage that a high quality vinyl chloride polymer with fewer fish eyes can be obtained.

The present invention will be explained in detail below.

In carrying out the method of the present invention, it is first necessary to mix the vinyl chloride monomer, a polymerization initiator, a dispersant, and additives used as necessary simultaneously at a uniform temperature. If it is uniform, scale may form on the wall of the polymerization vessel,
The quality of the polymer obtained is inadequate.

The method for uniform mixing is to uniformly mix the vinyl chloride monomer, polymerization initiator, dispersant, and additives in a suitable tank or continuous mixer, and then charge them into a polymerization container, or to mix them separately. The mixture is charged into a polymerization vessel and then homogeneously mixed (either method is acceptable).

When uniformly mixing the vinyl chloride monomer, polymerization initiator, dispersant, additives, etc., it is necessary to keep the temperature of the mixture below 40°C. If this condition is not met, scale will be generated and the resulting polymer will have coarse particles and many fish eyes.

In addition, when uniformly mixing vinyl chloride monomers, polymerization initiators, dispersants, additives, etc., vinyl chloride monoelectric phase (
If this condition is not met, the polymerization DH initiator concentration and additive concentration between the monomer droplets will be uneven, and the resulting polymer will have many fish eyes. The quality may vary.

Additives that can be homogeneously mixed with the vinyl chloride monomer, polymerization initiator, and dispersant as needed include polymerization degree regulators, polymerization inhibitors, processability improvers, antistatic agents, and pH adjusters. can give. These additives may be added by dissolving them in solvent C2 or dispersing them in an aqueous medium.
Form of preparation (no two fits.

＼ Vinyl chloride filament, polymerization initiator, dispersant and additive +1
After forming a uniformly mixed system with agent 11, a heated aqueous medium is charged to start the polymerization reaction, and the temperature of the aqueous medium at this time is such that the temperature of the ζ double platform system reaches the target temperature when the preparation is completed. The temperature is determined in consideration of heat dissipation, heat of polymerization during preparation, etc., so that the polymerization temperature is such that the turbid polymerization reaction can proceed satisfactorily. If the temperature of the polymerization system is too high than the predetermined temperature upon completion of charging, the polymerization reaction will proceed rapidly, making it difficult to control the reaction, which is not only dangerous but also undesirable from the point of view of energy conservation. On the other hand, if the temperature is too low, a corresponding amount of time will be required to raise the temperature to a predetermined polymerization temperature, which defeats the purpose of shortening the heating time.

The heated aqueous medium must be stirred twice, otherwise there will be a lot of scale attached to the polymerization vessel, and the resulting polymer will be of low quality with many buish eyes.

The dispersants used above may be those commonly used in the polymerization of vinyl chloride in aqueous media, including water-soluble cellulose ethers such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, etc. Saponified polyvinyl alcohol, acrylic acid polymers, water-soluble polymers such as gelatin, oil-soluble emulsifiers such as sorbitan monolaurate, sorbitan triolate, glycerin tristearate, ethylene oxide v dobrobylene ox v block copolymers, polyoxyethylene sorbitan mono Examples include water-soluble emulsifiers such as laurate, polyoxyethylene glycerin oleate, and sodium laurate, which may be added singly or in combination of two or more.

The above-mentioned dispersant is initially charged at 8 units with the vinyl chloride monomer, polymerization initiator, and additives used as necessary and mixed uniformly. It is not necessary to add it to the polymerization system, and it may be added in portions to the polymerization system. However, it is desirable that at least 20% by weight of the total amount used is initially charged into the homogeneous mixing system.

On the other hand, the polymerization initiator may also be one conventionally used in the polymerization of vinyl chloride, such as diisopropyl peroxydicarbonate% di-2-ethylhexyl peroxydicarbonate, jetoxyethyl peroxydicarbonate, etc. bar carbonate compounds, perester compounds such as t-butylperoxyneodecanate, α-cumylperoxyneodecanate, t-butylperoxyneodecanate, acetylcyclohexylsulfonyl peroxide, 2,4. 4-to・1 meter・re, 7・−
Peroxides such as 2-peroxyphenoxyacetate, azobis-2,4-dimethylvaleronitrile, azobis(
Azo compounds such as 4-methoxy-2,4-dimethylvaleronitrile), potassium persulfate, ammonium persulfate, hydrogen peroxide, etc. can be used alone or in combination.

It is used as necessary in the present invention. Various additives include polymerization degree regulators such as acetaldehyde, butyraldehyde, trichloroethylene, perchlorethylene or mercaptans, phenolic compounds, sulfur compounds,
These include polymerization inhibitors such as N-oxide compounds, as well as oil-soluble surfactants, low saponification polyvinyl algol, and higher alcohols used for purposes such as improving processability, improving plasticizer absorption, and preventing static electricity. It will be done. Further, it is also optional to add a pH adjuster, a scale inhibitor, a crosslinking agent, etc., and a plurality of the above additives may be used in combination.

The vinyl chloride monomer polymerized in the method of the present invention includes vinyl chloride alone, as well as monomer mixtures mainly composed of vinyl chloride (vinyl chloride 50 [i% by weight or more)],
Comonomers copolymerized with vinyl chloride include vinyl acetate, vinyl propionate, vinyl esters,
Methyl acrylate.

Examples include acrylic esters or methacrylic esters such as ethyl acrylate, olefins such as ethylene and propylene, maleic anhydride, acrylonitrile, styrene, vinylidene chloride, and other layer monomers copolymerizable with vinyl chloride.

In carrying out the method of the present invention, the charging ratio of each component,
There are no particular limitations on the W synthesis temperature, etc., as long as they are determined according to the conditions conventionally employed in the suspension polymerization of vinyl chloride.

As described above, according to the present invention, the polymerization time for one batch can be significantly shortened, and commercially available vinyl chloride polymers with fewer fish eyes can be obtained over a wide variety of grades.

Next, a specific experimental example will be given.

[Experiment/161-7] Internal volume 1 equipped with a stirring device and having a jacket on the outer periphery
The following polymerization was carried out using a 00 polymerization vessel.

First, after evacuating the inside of the polymerization vessel, vinyl chloride (V
36 stamps of partially saponified polyvinyl alcohol (trade name, Nippon Gohsei Co., Ltd., Gohsenol K) were prepared.
H-2()'j and hydroxypropyl methylcellulose (trade name, Metrose 60SH50, manufactured by Shin-Etsu Chemical) were dissolved in deionized water, and then di-2-ethylhexyl oxysilane dicarbonate as a polymerization initiator (
(abbreviated as opp) is 16.2? Added. After this, stirring was started to obtain a homogeneous mixing system. While continuing to stir, the heated aqueous medium and the remaining dispersant were added to the homogeneously mixed polymerization system to start the polymerization reaction, and the internal temperature was brought to 57.
°C I: Polymerization reaction was carried out under control.

When the polymerization approached the end and the internal pressure decreased to 6 My/cr/l G, unreacted monomers were collected and dehydrated and dried to obtain a vinyl chloride resin.

The total amount of partially saponified polyvinyl alcohol added as a dispersant was 21.6 KF, and the total amount of hydroxypropyl methylcellulose was 14.1'.

The total amount of water charged was 53 ni. Regarding conditions such as the dispersant added when uniformly mixing vinyl chloride monomer and polymerization initiator, the volume ratio of vinyl chloride monomer phase (oil phase) and water phase, and internal temperature during mixing, etc. As shown in Table 1.

The state of scale adhesion to the fish eyes and the inner wall of the polymerization vessel of the resin produced in this way, and the particle size distribution of the resin are as follows:
It was as shown in the table.

Fisheye (pcs) 100 parts by weight of vinyl chloride resin obtained by polymerization, 1 part by weight of tribasic lead sulfate, 1.5 parts by weight of lead stearate, 0.2 parts by weight of titanium dioxide, 0.1 part by weight of carbon black. 25 parts by weight of Funbound 25 mixed with 50 parts by weight of DOP were kneaded at 145°C for 5 minutes, separated into a 0.2 mm thick sheet, and expressed as the number of transparent particles in 10 oa/l of this sheet. Ta.

Scale adhesion condition ○There is almost no adhesion of Niscale.

△: Scale adhesion at the air-liquid interface.

×There is scale adhering to the entire inner wall of the double metal lid.

[Experiment A8] Using the same polymerization vessel as in the previous experimental example, partially saponified polyvinyl alcohol (-f--k)-ol KH-20) 21.6/
- and hydroxypropyl methylcellulose (Metrose 60SH50) 14.4. P was dissolved in deionized water 53IIP and charged by heating to 67.5°C, and after the inside of the polymerization vessel was evacuated, vinyl chloride 36 glue was charged. 0PP16.2i as a polymerization initiator after starting stirring! - was added to initiate polymerization.

When the internal pressure was lowered from 6 kg/cl.sub.o to 2, the same treatment as in the previous experimental example was carried out to obtain a vinyl chloride resin. The results are shown in Table 1C2.

[Experiment A69-11] In a polymerization vessel equipped with a condenser with an internal volume of 40 m' and a heat transfer area of 40 mm, vinyl chloride (13) was charged, and partially saponified polyvinyl alcohol (2.5 Kl) and hydroxypropyl methylcellulose (2.5 Kl) were added. Deionized water 100%! It was dissolved in and prepared. Next, 0PP5.9 loss was added to Preparation A, and stirring was started to uniformly mix the mixture. The reaction was started by adding 18 ml of heated deionized water with continued stirring.

The condenser was opened for 1 hour after charging with deionized water. The failure is nearing the end and the internal pressure is 7Kylct! When the temperature decreased to a, unreacted vinyl chloride was collected and dehydrated and dried.

The results are shown in Table 2.

Table 2 [Experiment 7 g 612] After degassing a stainless steel polymerization vessel with an internal volume of 2,1-, vinyl chloride monomer 500 KIL and vinyl acetate monomer 1
00 soy, then partially saponified polyvinyl alcohol 4007F- and hydroxypropyl methylcellulose 2,0OF- 30! Prepared by dissolving in deionized water,
Di4-soprovil peroxide (dicarbonate) 1209 was charged. After the preparation was completed, stirring was started to ensure uniform mixing. The internal temperature of the polymerization vessel at this time was 25°C. While stirring was continued, 900 g of deionized water heated to 67° C. was added to start the polymerization reaction. The internal temperature at the time of completion of charging deionized water was 58°C, and the jacket humidity was controlled to maintain the internal temperature at 58°C throughout the polymerization.

When the internal pressure of the polymerization vessel dropped to 2 HP/ct/la, unreacted monomers were collected and dehydrated and dried.

The obtained polymer had good particle size distribution, BD, and other physical properties. Moreover, there was almost no scale attached inside the polymerization vessel.

[Experiments A13-17] The following polymerization was carried out using the same polymerization vessel as in Experiments/%1-7.

First, after evacuating the inside of the polymerization vessel, vinyl chloride (Va
), and then 10.8 kg of partially saponified polyvinyl alcohol (Gohsenol KH-20). P and hydroxypropyl methylcellulose (Metrose 608)
150) 7.2iP was dissolved in deionized water and added, and 16.2. P and 0.361 of butylhydroxyanisole (Wako Tsumugi Pharmaceutical Co., Ltd. B) IA) as a polymerization inhibitor were added.

After that, stirring was started to form a homogeneous mixing system, and the heated aqueous medium was charged to start the polymerization reaction. The polymerization reaction was carried out while controlling the internal temperature at 57°C, and when the internal pressure decreased to 6 Ky/ad G, unreacted monomers were collected and dehydrated and dried to obtain a vinyl chloride resin.

The total amount of water charged was 53%, and the conditions such as the volume ratio of the vinyl chloride monomer phase (oil phase) and the water phase, and the internal temperature during uniform mixing were as shown in Table 3. . The state of scale adhesion of the thus produced resin to the fish eyes and the inner wall of the polymerization vessel was as shown in Table 3.

[Experiment/161@] Using a polymerization vessel similar to Experiment/I61-7, 10.8y- of partially saponified polyvinyl alcohol and 7.21% of hydroxypropyl methyl cellulose were dissolved in 53% of deionized water and heated to 67.5°C. After heating and creating a vacuum inside the polymerization vessel,
Vinyl chloride monomer 36KP was charged. After starting stirring, add 0 butylhydroxyanisole as a polymerization inhibitor.
．． 361P was charged, and after 5 minutes, op' as a polymerization initiator was added.
16.2 # of p was added to initiate polymerization. Internal pressure is 611
When the pressure was lowered to 5t/cnG, the same treatment as in Experiments AI3-17 was carried out to obtain a vinyl chloride resin. The results are shown in Table 3.

[Experimental rot 19] Low saponification degree low viscosity polyvinyl alcohol (trade name Gohsenol G manufactured by Nippon Gosei Co., Ltd.) was used instead of the polymerization inhibitor as an additive.
Experiment 7 except that a5-5307) 25.29- was prepared.
It was carried out according to f613. The results are shown in Table 4.

[Experiment) 20] Instead of the polymerization inhibitor as an additive, sorbitan monostearate (trade name Span'I'S-11 manufactured by Kao Atlas) was used.
05) The procedure was carried out in accordance with Experimental Washing 13 except that 367 was added. The results are shown in Table 4.

[Experiment/%21] Low saponification degree low viscosity polyvinyl alcohol (Gas-5307) 25.2? The experiment was carried out in accordance with Experiment/%18 except that . The results are shown in Table 4.

[Experiment 422] Experiment 422 was carried out in accordance with Experiment 1618, except that 36 g of sorbitan monostearate (span T8=1105) was added in place of the polymerization inhibitor as an additive.

The results are shown in Table 4.

Note that the dry-up properties and gelation properties in Table 4 were measured as follows.

[Dry-up property]

Polymer powder 400 in Plastograph (planetary mixer)? and preheat it while stirring at 60 rpm (
4 minutes) to 80°C, and then put DOP [gelling property] into a Plastograph (model 50 kneader) with a formulation 65f similar to the above-mentioned stabilizer retention performance, and heated to 190°C.
The time (minutes) from when stirring was started at a rotational speed of 6 Or p m (°C) until the maximum torque was reached was defined as the time (min).

Claims (1)

[Scope of Claims] 1. A vinyl chloride-based material, a polymerization initiator, a dispersant, and optional additives obtained from 7JO are mixed uniformly at a temperature of 40°C or less, and then added to this mixed system while stirring. 7J
11 Suspension polymerization method of vinyl chloride medium weight method characterized by adding a hydrothermal medium to cause a polymerization reaction 2, the vinyl chloride monomer, a polymerization initiator, a dispersant and In the homogeneous mixing system of the additive IJ11 agent, the volume ratio of the vinyl chloride system to the aqueous phase is as follows. Turbid polymerization method