JPH0635484B2 - Organic peroxide emulsion formulations - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an emulsion blend of an organic peroxide, which is a mixture with vinyl chloride and another vinyl-based monomer containing vinyl chloride as a main component. Can be used as an initiator of the suspension polymerization of.

[Conventional technology]

Polymerization of vinyl chloride and copolymerization with other vinyl-based monomers containing vinyl chloride as a main component have been carried out on an industrial scale by suspension polymerization for a long time, but during that time, the size of the polymerization equipment was increased and productivity was improved. Has been promoted.

An organic peroxide has been generally used as a polymerization initiator. In the early days, lauryl peroxide (LPO), which was relatively easy to handle, was used, but recently, for the purpose of improving the productivity of vinyl chloride polymerization, various highly active liquid organic peroxides such as dioxane have been recently used. -2-Ethylhexyl-peroxydicarbonate (EHP), t-butylperoxyvivarate (TBPP), t-butylperoxyneodecanoate (TBPND), α-cumylperoxyneodecanoate (CPND), etc. Is being used. These highly active organic peroxides are highly reactive, unstable and dangerous substances. Even if it is heated to room temperature, it may cause a rapid exothermic decomposition, which may cause a fire or explosion.

In order to further rationalize the polymerization, an automatic addition method using a pump or the like of these highly active organic peroxides has been studied, but the danger becomes an obstacle, and most of the addition methods by hand are unavoidable as in the past. It is done in a company.

Against this background, in order to enhance the safety of these highly active organic peroxides, emulsion formation of these organic peroxides has been proposed. Furthermore, these organic peroxide emulsions must have a viscosity such that they can be pumped at low temperatures for that purpose.

Japanese Unexamined Patent Publication No. 56-139509 discloses an aqueous organic peroxide emulsion using alcohols as an antifreezing agent and cationic, anionic or nonionic surfactants as an emulsion stabilizer.

JP-A-58-134103 discloses an aqueous organic peroxide emulsion using an alcohol having a molecular weight of 100 or less as an antifreezing agent and a nonionic surfactant as an emulsion stabilizer.

So far, aqueous emulsification of these highly active organic peroxides has been possible with the above formulation,
As seen in these patents, there has been a problem that various surfactants must be used as emulsion stabilizers essential for emulsification.

Suspension polymerization of vinyl chloride is carried out using polyvinyl alcohol (PVA), alkoxy cellulose or the like as a suspending agent while maintaining a very delicate balance. Therefore, even a very small amount of the emulsion stabilizer used for emulsification of the organic peroxide as the initiator has a significant influence on the control of the polymerization and the properties of the obtained polyvinyl chloride particles. Therefore, an emulsion of an organic peroxide using PVA that does not adversely affect the suspension polymerization of vinyl chloride as an emulsion stabilizer has been required. It was not possible to obtain stable emulsion formulations of these organic peroxides in systems containing agents.

[Means for solving problems]

The present invention has solved the above-mentioned problems, and uses a partially saponified polyvinyl acetate as an emulsion stabilizer, which has a low viscosity even at a low temperature and can be automatically added using a pump or the like and has a high safety. In addition, the object is to produce a stable organic peroxide emulsion.

Therefore, the present inventors first investigated an emulsion consisting of an organic peroxide, water, and an antifreezing agent by using PVA usually used for suspension polymerization of vinyl chloride, but a safe emulsion was obtained. Not obtained (Example 1, Experiment No.
1-5, 10-12))).

PVA (polyvinyl alcohol) referred to here is one that is usually used in suspension polymerization of vinyl chloride, and in addition to completely saponified polyvinyl acetate, a polyvinyl acetate moiety in which saponification exceeds 70 mol (%). It also contains saponified products.

However, it was found that the stability of emulsion is increased when the saponification degree is within a certain range, and the present invention was achieved based on this finding.

The present invention solves the above problem by using a partially saponified polyvinyl acetate having a saponification degree of 5 to 70 mol (%) as an emulsion stabilizer. That is, the present invention is an emulsion blend of an organic peroxide having a freezing point of 0 ° C. or less, which is characterized by blending a partially saponified polyvinyl acetate having a saponification degree of 5 to 70 mol (%) as an emulsion stabilizer. .

The partially saponified polyvinyl acetate used is in the above range, but more desirably, the saponification degree is 35 to 70 mol (%).
It is more preferably 50 to 70 mol (%), and the addition amount thereof is preferably 0.1 to 10% in emulsion.
Specifically, Unitika Resin UMR series (saponification degree: 5-70 mol (%); Unitika Chemical Co., Ltd. trade name) can be used.

The emulsification stabilizer of the present invention has a saponification degree of 5 to 70 mol (%).
Partially saponified polyvinyl acetate is used, but in order to increase the stability of emulsion, a nonionic surfactant or P
VA or the like may be added.

It is preferable to use an organic peroxide having a freezing point of 0 ° C. or lower and a temperature showing a 10-hour half-life of 80 ° C. or lower, which is contained in the emulsion in an amount of 10 to 80%.
5-60% is preferable. Suitable organic peroxides include peresters, percarbonates and diacyl peroxides.

Specifically, trimethylpentyl-2-peroxyphenoxyacetate, α-cumylperoxyneodecanoate (CPND), t-butylperoxyneodecanoate (TBPND), t-amylperoxyneodeca Noate, trimethylpentyl-2-peroxy-neodecanoate (TMPND), t-butylperoxypivalate (TBPP), t-amylperoxypivalate, trimethylpentyl-2-peroxypivalate,
t-butylperoxy-2-ethylhexanoate, t
-Amylperoxy-2-ethylhexanoate, trimethylpentyl-2-peroxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-amyl-peroxyisobutyrate, trimethylpentyl-2- Peroxyisobutyrate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate (EHP), di-sec-butyl peroxydicarbonate, isobutyl peroxide, 2,4-dichlorobenzoyl Examples thereof include peroxide and bis-3,5,5-trimethylhexanoyl-peroxide.

Further, these organic peroxides, whether they are pure or diluted with a hydrocarbon solvent or a plasticizer, can be used as long as their freezing points are 0 ° C or lower.

As the antifreezing agent, one or more kinds are selected from alcohols having 1 to 4 carbon atoms and diols having 2 to 4 carbon atoms and used. Specifically, methanol, ethanol, n
-Propanol, iso-propanol, n-butanol, ethylene glycol, propylene glycol, diethylene glycol and the like. The amount of addition is determined by the storage temperature of the organic peroxide, but it is 1% of the whole emulsion.
It accounts for ~ 40%.

Further, a solvent may be added for the purpose of preventing layer separation of emulsion. For example, n-hexane, toluene, xylene, IP-solvent (Idemitsu Petrochemical
Hydrocarbon solvent such as (trade name), DBP, DOP,
A plasticizer such as DOA and a chlorinated solvent such as methylene chloride, carbon tetrachloride and tetrachloroethylene can be used.

The emulsification can be performed by a commonly used method. That is, any of a paddle type, a propeller type, a turbine type mechanical rotary agitator, a colloid mill, a homogenizer, a homodisper, a high speed shear emulsifier, and an ultrasonic homogenizer can be used.

〔Example〕

 Hereinafter, the present invention will be specifically described based on Examples.

Example 1 Selection of partially saponified polyvinyl acetate di-2-
Ethylhexyl peroxydicarbonate (EHP, Kayaku Nouri Co. 40%, water 35%, methanol 1%
In a system containing 1% and 12% ethylene glycol, the amount of partially saponified polyvinyl acetate was set to 1%, and the results obtained by emulsification of those having different saponification degrees are summarized in Table 1. Stirring with a homodisper was carried out at 10 ° C. or lower, and the stability of emulsion was expressed by the time until layer separation was observed. That is, ◎ indicates that layer separation was not observed for more than 1 month, ◯ indicates that layer separation was observed between 1 week and 1 month, and 1 day to 1 week within △ 1 day. The separated layers are represented by x.
As a result, the saponification degree of the partially saponified polyvinyl acetate is 50.
~ 70 mol (%) was found to be the best.

Next, an example using t-butylperoxyneodecanoate (TBPND) as another organic peroxide is shown. TB
40% PND (made by Kayaku Nouri Co., Ltd.), 34% water,
In a system containing 17% methanol and 6% ethylene glycol, as in the case of EHP, the amount of partially saponified polyvinyl acetate was set to 1%, and emulsions of different saponification degrees were emulsified. Summarized in 2.
From this, it was found that the optimum value of the saponification degree of the partially saponified polyvinyl acetate was 50 to 70 mol (%) as in the case of EHP.

Example 2 Addition of Plasticizer etc. Next, the effect of adding a solvent other than that used for the organic peroxide was examined. That is, DOP as a plasticizer or carbon tetrachloride as a chlorine-based solvent is added to TB.
The emulsion was prepared by adding 5 to 10% to PND to examine its stability. The results are summarized in Table 3.
It was found that the stability of emulsion was greatly improved by adding DOP and carbon tetrachloride.

Example 3 Emulsion of various organic peroxides The results of emulsification of various organic peroxides are summarized in Table 4. Both are partially saponified polyvinyl acetate,
Unitikarange UMR-10M (saponification degree 50 or 6
5 mol (%); Unitika Kasei Co., Ltd.) was used.

As shown above, the organic peroxide having a freezing point of 0 ° C. or lower and a 10-hour half-life temperature of 80 ° C. or lower has an saponification degree of 5 to 70 mol as an emulsion stabilizer.
By using (%) partially saponified polyvinyl acetate and using methanol and ethylene glycol together as an antifreezing agent, it was possible to obtain a stable and low viscosity emulsion.

Example 4 Polymerization of Vinyl Chloride It was investigated whether the emulsion of the organic peroxide described above can be used for suspension polymerization of vinyl chloride.

That is, 0.13 g of PVA (E, saponification degree: 73 mol%) and 0.8 g of sodium hydrogen carbonate were placed in a glass autoclave.
Was dissolved in 370 g of water to prepare a nitrogen atmosphere. At room temperature, either the above-mentioned organic peroxide emulsion or a commercial product of the same organic peroxide for comparison was added by the weight in the table, and then 185 g of vinyl chloride monomer was added.

This was reacted at 55 ° C. for 7 hours while stirring well. The obtained polymer was taken out, washed with water and dried at 50 ° C. overnight.
The results are summarized in Table 5.

From this result, the organic peroxide emulsion of the present invention,
It was found that it can be used as an initiator for suspension polymerization of vinyl chloride without any difference from organic peroxides such as solvent dilution that have been used so far.

〔The invention's effect〕

According to the present invention, it is possible to obtain a stable emulsion having a low viscosity of a highly active organic peroxide even at a low temperature, and as a result, automatic addition is possible, and its effect on safety and labor saving is very large.

Another feature of the present invention is that, unlike the conventional emulsions of organic peroxides, it does not contain a surfactant and therefore has no adverse effect on the suspension polymerization of vinyl chloride and the physical properties of the obtained polymer.

Continuation of the front page (56) Reference JP-A-59-68303 (JP, A) JP-A-61-130372 (JP, A) JP-A-56-139509 (JP, A)

Claims (1)

[Claims] 1. An emulsion composition of an organic peroxide having a freezing point of 0 ° C. or lower, which is characterized by blending a partially saponified polyvinyl acetate having a saponification degree of 5 to 70 mol (%) as an emulsion stabilizer.