JPS6187659A - Aqueous suspension containing organic peroxide - Google Patents

Abstract

PURPOSE:To obtain an aqueous suspension containing an organic peroxide, useful as a polymerization initiator of polystyrene, etc., and transport able with a pump without causing clogging, by using tribasic calcium phosphate as an active component. CONSTITUTION:An aqueous suspension containing an organic peroxide is prepared by compounding tribasic calcium phosphate. The liquid can be prepared e.g. by adding a necessary amount of tribasic calcium phosphate to a definite amount of water, dispersing under stirring, optionally adding and dispersing a dispersion stabilizing assistant in the dispersion, adding a required amount of powder (benzoyl peroxide) moistened with water, and stirring the mixture. Even if a partial phase-separation takes place in the above suspension, the suspension can be homogenized easily by the light shaking or stirring, to enable the approach to the practical adoption of the automatic charging system with a pump. In the conventional process, the charge of the peroxide has to be carried out through a manhole and accordingly the operation of a polymerization plant in closed system has been impossible. The present process clears the way for the operation of the plant in closed system.

Description

[Detailed Description of the Invention] - [Industrial Application Field] The present invention relates to an organic peroxide used as a polymerization initiator for suspension polymerization of polystyrene, polymethyl methacrylate styrene acrylonitrile copolymer, [ABS copolymer, etc.] The present invention relates to aqueous suspensions containing substances.

[Conventional technology]

Benzoyl peroxide (hereinafter referred to as B) is generally used as a polymerization initiator for suspension polymerization of styrenic and acrylic monomers.
However, since BPO is in powder form, unlike other liquid initiators, it cannot be automatically charged using a pump, etc., which is a bottleneck that hinders labor-saving manufacturing operations for these polymers. It becomes.

In order to improve this point and enable automatic preparation using a pump, attempts have been made to formulate an aqueous suspension of BPO (Japanese Unexamined Patent Publication No. 51-125302). In combination with a nonionic emulsifier with HLB=10, a pumpable aqueous suspension containing 50% BPO was obtained.

Problems to be Solved by the Invention 5] However, this formulation lacks long-term dispersion stability, and when stored for a long period of time, it settles in the form of mud on the bottom. Moreover, -supported and deposited BPO is not easily redispersed. Rather, the fundamental problem with this BPO suspension is that it lacks stability in transport by pumps, which is the purpose of this suspension.
. Initially, the liquid is transferred smoothly, but eventually the inside of the pump or some of the piping becomes clogged, making transportation impossible. For these reasons, aqueous suspensions of powdered organic peroxides, mainly BPO, have not been put to practical use.

[Means to solve the problem]

The present inventors have considered the problem of powdered polymerization initiators, mainly BPO, and have developed powdered polymerization that uses water as a medium, has long-term dispersion stability, and does not clog pumps or piping even when pumped. As a result of extensive research into the formulation and manufacturing method of initiator formulations, the inventors succeeded in finding an aqueous suspension that satisfies this purpose, leading to the completion of the present invention. That is, the present invention is an organic peroxide-containing aqueous suspension characterized by containing tricalcium phosphate.

The present invention can be easily implemented, for example, as follows.

That is, a required amount of tricalcium phosphate as a dispersant is added to a predetermined amount of water, and dispersed with stirring.Additionally, if necessary, a dispersion stabilizing agent is added, dispersed with stirring, and then The desired aqueous suspension of BPO can be obtained by simply adding a predetermined amount of wet powder BPO into the container and stirring for a predetermined period of time.

When the aqueous suspension of the present invention is stored at room temperature for a long period of time, it may sometimes appear that the aqueous phase and the BPO solid layer separate, but even in such cases, shake it gently or
Alternatively, it is possible to achieve uniform dispersion by simply applying gentle stirring. Aqueous suspensions of BPO produced by conventional methods have a high density of BPO itself (1,33
/25°C), during long-term storage, the layers separated and then gradually solidified, making it difficult to homogenize the dispersion by simply applying light shaking or gentle agitation. .

Surprisingly, as mentioned above, the aqueous suspension of the present invention can be easily uniformly dispersed even if it exhibits a partial layer separation phenomenon. It is possible to take a step forward in realizing the adoption of the preparation method.

As the organic peroxide used in the present invention, powdery BPO
However, it is not limited to this BPO, and in addition, lauroyl peroxide, 0-methylbenzoyl peroxide, 0-chlorobenzoyl peroxide, p-
Those that are solid at room temperature (approximately 20°C) such as chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butylperoxyhexahydroterephthanate, and di-t-butylperoxyterephthalate. is used, and there is no problem in widely applying the present invention. These may be pure or the latter may be advantageously used. Moreover, the organic peroxides are not limited to the use of one type alone, and there is no problem even if a mixture of two or more types is used. The total amount of organic peroxide used is 5 to 70% in terms of pure product.
It is preferably 55% by weight or less, more preferably 55% by weight or less.

The amount of tricalcium phosphate used in the present invention is preferably 0.5 to 20%, more preferably 1 to 10% of the aqueous suspension.

In addition, in order to enhance the dispersion stability effect as necessary, synthetic polymers such as polyvinyl alcohol and polyethylene oxide, cellulose derivatives such as methyl cellulose and carboxymethyl cellulose, animal protein such as glue and gelatin may be used as dispersion stabilizing aids. Bacterium, vegetable substances such as gum arabic and xanthan gum, seaweed-derived substances such as alginic ferment, other starches, and eggplant powder are used, and solid fine particles such as calcium carbonate and barium sulfate are also added. Show effectiveness. In addition, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium oleate,
Kaoquin and nonionic surfactants are used. These can also be used in any combination of one or more of the above-mentioned dispersants.

The water used may be tap water, but ion-exchanged water or distilled water is usually preferable, and the amount of water is preferably 30 to 95% by weight.

It is also possible to dissolve water-soluble organic substances in water for the purpose of antifreezing aqueous suspensions.

Here, the water-soluble organic substance is a monovalent or divalent lower alcohol such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and ethylene glycol. Of course, it is not always necessary to dissolve water-soluble organic substances in water.

〔Example〕

Hereinafter, the aqueous turbidity of the present invention will be further explained with reference to Examples and Comparative Examples.

Example 1 Into a 500ynl tall beaker equipped with a conventional homomixer and a thermometer, 107.5 g of ion-exchanged water (43% by weight) was added, followed by 7,5 P of tricalcium phosphate.
(3% by weight) was added, and while stirring, the pre-weighed B
135.0 g (54% by weight) of 75% water wet PO was gradually added, and stirring was continued for 20 minutes while keeping the temperature below 20'C to obtain a white aqueous suspension. The viscosity of this product is 25
It was 0 cps/20°C. It also showed dispersion stability for about 20 days. After 20 days, a stable suspension was again obtained with gentle shaking.

Example 2 In Example 1, aqueous suspension was attempted in the case where tricalcium phosphate was 10% by weight. The viscosity of this product is 30
It showed dispersion stability of 0 cps for 30 days. After 30 days, a stable suspension was again obtained with gentle shaking and 5°C.

Example 3 In Example 1, aqueous suspension was attempted by adding 0.4% by weight of sodium dotecylbenzenesulfonate as a dispersion stabilizing aid. The viscosity was 270 cps, and the dispersion was stable for 40 days. After 40 days, a stable 100ml suspension was again obtained by shaking the mixture.

Example 4゜In Example 1, polyvinyl alcohol was further added as a dispersion stabilizing agent to obtain an aqueous suspension.Example 5゜Sister Example 4, methanol was used as an antifreeze agent. Aqueous suspension was attempted and an aqueous suspension was obtained.

Example 6゜Actual! (!1113, an aqueous suspension was obtained using lauroyl peroxide (LPO) as an organic peroxide.

In 9v application 1 and 117° implementation II 3, di was used as the organic peroxide, monobutylperoxyhexahydrothylephthalate) (H
An aqueous suspension was obtained by attempting turbidity using TP).

Comparative Example 1 In a practical example of 1 flllll, an aqueous suspension was obtained in a system without the addition of tricalcium phosphate as a dispersant.

Comparative Example 2 In Example 1, an aqueous suspension was obtained by using sodium oleate instead of tricalcium phosphate as a dispersant to try to make the aqueous i'W turbid.

Comparative Example 3 Composition and aqueous composition of Example 1 of JP-A-51-125302! ° The characteristics of the suspension are cited.

Actual examples 1 to 7 and comparative examples 1 to 3 are summarized in Table 1.

Application Example 1゜ As shown in the above-mentioned Examples and Comparative Examples. The diaphragm pump (Ikki HD) offers the possibility of pumping aqueous suspensions.
A continuous circulation operation of the aqueous suspension was carried out at room temperature (20 to 30° C.) using the P type.

After operating for a predetermined period of time, the pump was disassembled and evaluated by observing whether there was any solid matter remaining in the vicinity of the ball pulp. The results are summarized in Table 2.

〔Effect of the invention〕

The present invention has made it possible to transport powdered organic peroxides using a pump, which has not been possible until now.
This opens the door to closed polymerization plants, which was not possible because powdered organic peroxides such as powders had to be injected through manholes.

Claims (1)

[Claims] Organic peroxide-containing aqueous suspension characterized by containing tricalcium phosphate