JPS5846133B2 - Bulk polymerization method of vinyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bulk polymerization method for vinyl chloride or a copolymer graft polymer mainly composed of vinyl chloride.

Conventionally, when carrying out bulk polymerization, a method is known in which the polymerization is carried out under high-speed stirring at the initial stage of the polymerization in order to relatively reduce the particle size of the polymer and its variation.

(Special Publication No. 43-6634). In bulk polymerization reactions, increasing the stirring speed at the initial stage of polymerization has the effect of reducing the particle size, but considering the variation in particle size of the polymer and even the shape of the particles, it is difficult to simply perform high-speed stirring during the polymerization reaction and reduce the baffle size. Simply combining the shapes appropriately does not necessarily result in a satisfactory polymer, such as the generation of coarse particles.

Furthermore, high-speed stirring equipment is expensive when operating on an industrial scale.

The present inventors have completed the present invention as a result of extensive research into methods for appropriately adjusting the particle size, dispersion, and shape of polymers without significantly increasing the stirring speed in bulk polymerization reactions. .

That is, the present invention relates to a method for producing a polymer having extremely uniform particle size, variation, and shape by using certain additives during bulk polymerization of vinyl chloride or the like.

In the present invention, the additive added during the polymerization reaction is a cellulose derivative.

Cellulose derivatives are not particularly limited as long as they are soluble in vinyl chloride monomers, and cellulose ethers such as methyl cellulose, ethyl cellulose,
Propyl cellulose and glycol cellulose can be mentioned, and the ratio of substituents in these compounds is not particularly limited.

It is sufficient that the amount of the cellulose derivative used in the present invention is from o,ooi to 2% by weight, preferably from 0.005 to 0.1% by weight, based on the vinyl chloride monomer.

Adding a small amount of cellulose derivative can be effective, but if it is too large, other properties of the polymer may be affected, such as transparency after molding,
It has a negative effect on hue, fish-eye characteristics, etc., so it is preferable to have as little as possible.

There are no particular restrictions on the method of adding the cellulose derivative to the polymerization reaction system; for example, it may be added before polymerization or sequentially during polymerization, especially at the beginning of polymerization.

Further, it may be added as it is all at once, or may be added after being dissolved in the monomer to be subjected to polymerization, or may be added after being dissolved in a solvent.

The polymerization temperature of the present invention is the usual polymerization temperature of vinyl chloride, that is, 4
The temperature range is 0°C to 80°C.

Further, the polymerization time varies depending on the type of polymerization initiator used, but is preferably about 30 minutes to 4 hours.

However, the polymerization time of the present invention must be within the period during which the vinyl chloride monomer in the liquid phase is present in the polymerization reaction system.

Furthermore, to explain in detail, the polymerization conversion rate expressed as ((amount of produced polymer/amount of vinyl chloride monomer) xlOO) is 2.
It is preferable to carry out the polymerization until a conversion of 0% by weight or less, particularly about 3 to 10% by weight, is reached.

If the polymerization conversion rate exceeds 20% by weight, the polymerization will be carried out in the absence of substantially any monomer in the liquid phase, which is undesirable in order to obtain the desired particle size and shape of the polymer. .

The present invention is applicable to the production of vinyl chloride copolymers and vinyl chloride graft polymers in addition to vinyl chloride polymers.

That is, monomers copolymerizable with vinyl chloride monomers, such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl butyrate, and/or polymers soluble in vinyl chloride monomers and graft copolymerizable with vinyl chloride, such as ethylene- This is the production of polymers such as vinyl acetate copolymers, copolymers or graft polymers of one or more of methyl methacrylate and vinyl chloride.

The amount of the copolymerizable or graft copolymerizable substance used may be 0.5 to 40% by weight, preferably 1 to 10% by weight, based on the amount of vinyl chloride monomer.

The polymerization initiator used in the present invention may be any radical initiator commonly used in the polymerization of vinyl chloride, but those that are soluble in vinyl chloride monomers are particularly preferred, such as acetyl peroxide, lauroyl peroxide,
・5,5-trimethylhexanoyl peroxide, acetylcyclohexylsulfonyl peroxide, t-
Butyl peroxybutyrate, t-butyl peroxy pivalate, t-butyl peroxy neodecanoate, diisopropyl peroxy dicarbonate, di-5ee-
Butyl peroxydicarbonate, bis-(4-t-7
Organic peroxides such as "tylcyclohexyl) peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate.

2,2'-Azohis-(2,4-dimethylvaleronitrile), 2,2'-Azobis-(4-methoxy-2,4-
dimethylvaleronitrile) and azo-based compounds such as azohisisobutyronitrile.

The polymerization initiators may be used alone or in combination of two or more.

The amount of polymerization initiator is 0.000 relative to vinyl chloride monomer.
It is in the range of 2 to 5% by weight, particularly preferably 0.001 to 0.00%.
It is 1% by weight.

Especially the method of adding polymerization initiator! IIJ%, the initiator may be added all at once to the reaction system before the start of polymerization, or may be added sequentially during polymerization, or the initiator may be added as it is, or it may be added by dissolving it in a monomer or diluent. It's okay.

The polymerization method may be batch polymerization or continuous polymerization, the polymerization vessel may be a seed type or a tube type, and the fluidization state of the reaction system must be maintained during the polymerization, but the fluidization method is not particularly limited.

For example, fluidization may be performed mechanically using a mechanical seal type stirrer or an electromagnetic stirrer, or fluidization may be performed using an orifice, a venturi, or the like.

When performing mechanical flow, a stirrer with stirring blades is required, but there are no restrictions on the shape of the stirring blades, and in most cases, seed-shaped stirring blades are used.

In the present invention, other additives can be used in combination with the cellulose derivative.

These include fish eye improvers, stabilizers, lubricants, plasticizers, emulsifiers, etc., and are not limited as long as they do not inhibit the polymerization reaction.

Normally, when these are added and polymerization is carried out, blocking tends to occur, but in the present invention, such alignment does not occur.

Additives that can be used in combination include higher alcohols, organometallic compounds, epoxy compounds, polyethylene waxes,
There is one or more types of esters, inorganic metal compounds, etc.

Further, the amount of these additives added is smaller than the amount added when processing the polymer.

That is, it varies depending on the additive, but it is 500 to 2000 pp.
It is m.

The method for adding these to the polymerization reaction system may be the same as that for adding the cellulose derivatives described above, and is not particularly limited.

When polymerization is carried out by the method of the present invention, the reactant is obtained as a monomer liquid in which the polymer is dispersed (hereinafter referred to as slurry) with a polymerization conversion rate of 20% by weight or less. It can also be obtained as a product through a separation operation.

The apparent specific gravity of the powdered polymer obtained at this time is 0.
05 to 0.3 gr/rrtl, and has a uniform particle size and shape.

Although the slurry can be further bulk polymerized,
Bulk polymerization can also be carried out by using the polymer in the slurry as a seed polymer and adding vinyl chloride monomer or the like to the reaction system.

The ratio of the slurry to the monomer newly added to the reaction system is not particularly limited, but is usually 10% to the slurry.
There is no problem in using a new radical initiator when carrying out bulk polymerization using the slurry of the present invention in which monomers are used in an amount of not more than 5 times by weight, preferably not more than 5 times by weight.
The radical initiator may be an organic peroxide or an azo compound commonly used in the polymerization of vinyl chloride as described above.

At this time, there is no particular restriction on the polymerization time, but the final polymerization conversion rate is preferably in the range of 60% to 95%.

If it is less than 60%, the productivity in industrial practice will be poor, and if the polymerization conversion rate is more than 95%, it will become a so-called "dead polymer" and a substantially useful polymer cannot be obtained.

Further, other polymerization conditions may be the same as those in ordinary bulk polymerization of vinyl chloride.

Of course, as in the case of adding cellulose and performing bulk polymerization, fish eye improvers, stabilizers, lubricants,
Polymerization can also be carried out by adding additives such as plasticizers and emulsifiers under the same conditions.

By adding a cellulose derivative and carrying out bulk polymerization as in the present invention, a vinyl chloride polymer having uniform particle size and shape can be obtained.

Furthermore, when the slurry obtained by this method is further subjected to bulk polymerization, a remarkable effect can be found in that the particle size of the finally obtained polymer can be adjusted to be extremely uniform.

Aspects of the present invention will be described in more detail with reference to Examples.

Example 1 Polymerization was carried out in a vertical polymerization vessel with a baffle having an internal volume of 100 mm, using a seed type stirring blade under the following conditions.

After the inside of the polymerization vessel was degassed, 40 kg of vinyl chloride monomer and 12 gr of ethyl cellulose (N-50 type manufactured by Vercules and the same below) were introduced and the temperature was raised.

When the temperature inside the can reached 59°C, it was dissolved in vinyl chloride monomer.

Acetylcyclohexylsulfonyl peroxide 2
I prepared gr.

Polymerization was carried out for 15 hours while stirring at a rotational speed of 540 r, p, m and maintaining the above temperature.

The slurry obtained after polymerization is separated into polymer and monomer.
Table 1 shows the particle size distribution and apparent density of the obtained polymer.

Example 2 Under the conditions of Example 1, the amount of ethyl cellulose added was 4 gr.
Polymerization was carried out in the same manner as in Example 1 except that the stirring rotational speed was changed to 74 or, pom.

Table 1 shows the particle size distribution and apparent density of the obtained polymer.

Comparative Examples 1 and 2 Polymerization was carried out under the same conditions as in Examples 1 and 2 except that the addition of ethyl cellulose was omitted.

Table 1 shows the particle size and apparent density of the obtained polymer.

Example 3 After degassing the same polymerization vessel as in Example 1, vinyl chloride monomer 4 was
0 kg, 8 gr of ethyl cellulose and 8 gr of stearyl alcohol were introduced.

When the polymerization temperature (59°C) was reached, the 2,2'-azobis-(4-methoxy-2
- 4g of 4-dimethylvaleronitrile) was charged to start polymerization.

During the polymerization, the stirring rotation speed was set to 74 Or, p, m, and polymerization was carried out for 2 hours.

After polymerization, the slurry was separated into polymer and monomer.

Table 2 shows the particle size distribution and apparent density of the polymer.

Comparative Example 3 Polymerization was carried out under the same conditions as in Example 3 except that ethyl cellulose was not added under the conditions of Example 30.

Table 2 shows the particle size distribution and apparent density of the obtained polymer.

Example 4 Polymerization was carried out under the same conditions as in Example 3, except that 8 grams of polyethylene wax was used instead of stearyl alcohol in Example 3.

Table 2 shows the particle size distribution and apparent density of the obtained polymer.

Example 5 Polymerization was carried out under the same conditions as in Example 3 except that 4 gr of calcium stearyl alcohol was used in place of stearyl alcohol in Example 3.

Table 2 shows the particle size distribution and apparent density of the obtained polymer.

Example 6 After degassing the same polymerization vessel as in Example 1, vinyl chloride monomer 4 was
0 kg, 60 gr of vinyl acetate and 8 gr of ethylcellulose were introduced.

When the polymerization temperature reached 65°C, 2g of acetylcyclohexylsulfonyl peroxide was dissolved in vinyl chloride monomer and charged.

During the polymerization, the stirring speed was set to 749 r, p, m, and the polymerization was carried out at the same temperature for 1.5 hours. Immediately after the polymerization, the polymer and monomer were separated from the slurry.

Table 3 shows the particle size distribution and apparent density of this polymer.

Example 7 After degassing the same polymerization vessel as in Example 1, 40 kg of vinyl chloride monomer, 30 gr of ethylene-vinyl acetate copolymer (Ultra Seven-Nine #630 manufactured by Toyo Soda Kogyo Co., Ltd.) and 8 gr of ethyl cellulose were introduced.

When the polymerization temperature (63°C) was reached, 2,2'-azobis-(4-methoxy-2
- 4g of 4-dimethylvaleronitrile) was charged.

After 2.5 hours of polymerization, the resulting slurry was separated into polymer and monomer.

Table 3 shows the particle size distribution and apparent density of the obtained polymer.

Example 8 and Comparative Example 4 A vertical polymerization vessel with an internal volume of 51 mm and equipped with a seed-shaped stirring blade was used. After degassing the polymerization vessel, 3 kg of vinyl chloride monomer and 0.9 gr of ethyl cellulose were charged and the inside of the vessel was heated to 59°C. When the temperature reached 59℃, 2 was dissolved in the monomer.
- 0.3 gr of 2'-azobis-(4-methoxy2,4-dimethylvaleronitrile) was added and polymerization was carried out for 2 hours.

During the polymerization, the stirring rotation speed was kept at 90 Or, plm.

The slurry obtained after 2 hours of polymerization was reduced to an internal volume of 201
The mixture was transferred to a horizontal polymerization vessel.

At this time, in the horizontal polymerization vessel, there will be ☆r (vinyl chloride monomer 9, 19 and t-butylperoxyneodecanoe).
I charged 1.5 gr.

Immediately after the slurry was transferred, the temperature of the horizontal polymerization vessel was raised to 59°C.

Polymerization was carried out for 9 hours, and during the polymerization, the hollow stirring blade was
Rotated by r, p, m.

After polymerization, 10 kg of powdered polymer was obtained.

The particle size distribution and apparent density of this polymer are shown in Table 4. Comparative Example 4 is the same as Example 8, except that ethyl cellulose was not added during the first stage polymerization, and all other conditions were the same as in Example 8. The same.

Claims (1)

[Claims] 1. In producing a polymer such as a vinyl chloride polymer, a vinyl chloride copolymer, or a vinyl chloride graft copolymer, 0, OO5 to o, i is added to the vinyl chloride monomer.
A polymerization method characterized in that bulk polymerization is carried out in the presence of % by weight of a cellulose derivative. 2. The method according to claim 1, which is carried out in the presence of a polymerization product slurry in which unreacted monomers remain.