JPH067916B2 - Aqueous emulsion organic peroxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an aqueous emulsified organic peroxide. More specifically, it relates to an aqueous emulsified organic peroxide having good stability. This aqueous emulsified organic peroxide is useful as a polymerization initiator suitable for the polymerization and copolymerization of ethylenically unsaturated monomers, particularly vinyl halide type monomers.

<Prior Art> Suspension or emulsion polymerization of an ethylenically unsaturated monomer usually uses a protective colloid agent and / or a surfactant in order to obtain a polymer having a desired particle size, and polymerizes in order to cause a polymerization reaction. This is done by using an initiator.

Recently, in order to improve productivity when polymerizing ethylenically unsaturated monomers, and to prevent environmental pollution due to toxicity of residual and waste monomers, the polymerization equipment is enlarged or the production equipment is automatically continuous. The entire polymerization reaction system is closed.

As a polymerization initiator suitable for such a purpose, an organic peroxide emulsified with water is easier to handle than a solvent-diluted organic peroxide that has been conventionally used, and is further excellent in safety. It tends to be preferred because it exists.

In recent years, various aqueous emulsified organic peroxides have been proposed in response to the above demands.

For example, JP-A-57-167733 discloses an organic peroxide, a lower alcohol and a specific nonionic surfactant,
That is, an aqueous emulsified organic peroxide containing a combination of a nonionic surfactant having an HLB value of 10 to 13 and a nonionic surfactant having an HLB value of 2 to 5 is disclosed.

JP-A-57-28106 discloses an aqueous emulsion containing an organic peroxide, a protective colloid agent, a lower alcohol and a nonionic surfactant containing no polyethylene oxide group, that is, sorbitan monolaurate or sorbitan monopalmitate. Organic peroxides are disclosed. However, the hydroxyl value of nonionic surfactants is usually within a wide range, for example, sorbitan monolaurate is 250-450 and sorbitan monopalmitate is 200-400. ing.

<Problems to be Solved by the Invention> These known aqueous emulsified organic peroxides include:
It has the following drawbacks. For example, JP-A-57-16773
The aqueous emulsified organic peroxide described in Japanese Patent No. 3 has poor storage stability and immediately separates into two layers. Moreover, the electrical properties of the polymer obtained using this are poor. That is, the volume resistivity of the polymer is reduced.

Further, both the storage stability of the aqueous emulsified organic peroxide and the electrical characteristics of the polymer described in JP-A-57-28106 are improved, but the production conditions may be slightly different, or the same raw material may be used. However, if the emulsification conditions are slightly changed, the properties of the prepared product are significantly deteriorated and the problem of layer separation is often caused. Also, if it is placed under a condition of vibrating for a long time, the viscosity is remarkably lowered and then it is separated into two layers. These phenomena become more remarkable as the proportion of oil content in the emulsion becomes higher, and become a serious problem at 50% by weight or more.

<Means for Solving the Problems> As a result of earnest research to obtain an aqueous emulsified organic peroxide without the above-mentioned drawbacks, the present inventors have found that a specific nonionic surfactant having a hydroxyl value in a specific range can be used. If the mixture contains a mixture, the storage stability will be good even if the production conditions change to some extent.
Further, it was confirmed that an aqueous emulsified organic peroxide which does not separate even when vibrated for a long time was obtained, and the present invention was completed.

That is, the present invention comprises a sorbitol, sorbitan and sorbite fatty acid ester having 10 to 22 carbon atoms, and the content of sorbitol fatty acid ester, sorbitan fatty acid ester and sorbite fatty acid ester is 1 to 30% by weight and 42 to 90% respectively. % By weight, 3 to 50% by weight, 0.1 to 10% by weight of nonionic surfactant having a hydroxyl value of 60 to 230, and 5 to 5% of organic peroxide.
The present invention relates to an aqueous emulsified organic peroxide containing 80% by weight, 2 to 30% by weight of a freezing point curing agent, or 0.1 to 10% by weight of a protective colloid as a substantial main component.

Next, each component of the aqueous emulsified organic peroxide of the present invention will be described.

(a) Nonionic Surfactant This nonionic surfactant is a mixture of predominantly mono, di and tri fatty acid esters made from sorbitol derivatives such as sorbitol, sorbitan and sorbide. Here, fatty acid is a general formula, (Where R = C _n H _{2n + 1} , H _n C _2n-1 , C _n H _2n-3 , C _n H _2n-5 , n = 9
~ 21). Specific examples of the fatty acid include linear and branched saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid and isostearic acid, for example, monoene unsaturated fatty acids such as oleic acid and elaidic acid, such as linoleic acid and ethanol. Polyene unsaturated fatty acids such as rheostearic acid and linolenic acid, oxygen-containing fatty acids such as ricinoleic acid, and fatty acids from natural products such as corn oil fatty acid, olive oil fatty acid, rice bran oil fatty acid, safflower oil fatty acid, tall oil fatty acid, etc. There is.

Further, the ratio of the sorbitol fatty acid ester, the sorbitan fatty acid ester, and the sorbide fatty acid ester is 1 to 30% by weight, 42 to 90% by weight, 3 to 50% by weight, and the hydroxyl value of the mixture of the nonionic surfactants is
Must be in the range 60-230. If the amount is out of the above range, the stability becomes poor. Here, the hydroxyl value is the number of mg of potassium hydroxide required to neutralize the acetic acid bound to the acetylated product obtained from 1 g of the sample oil.

The proportion of the nonionic surfactant in the aqueous emulsified organic peroxide is 0.1 to 10% by weight, preferably 0.5 to 5% by weight. If it is less than 0.1% by weight, the stability is not sufficient, and if it exceeds 10% by weight, not only the viscosity becomes too high but also it is economically disadvantageous.

The nonionic surfactant is a conventional nonionic surfactant, that is, propylene glycol fatty acid ester, sucrose fatty acid, within a range that does not significantly impair the physical properties of an aqueous emulsified organic peroxide or a polymer obtained using the same. A nonionic surfactant containing an ester or polyethylene oxide group may be contained.

(b) Organic peroxide The organic peroxide used in the present invention is usually one or more organic peroxides having a half-life of 10 hours and a temperature of 75 ° C or lower and a freezing point of 0 ° C or lower. is there. In this case, the present invention also includes a mixed organic peroxide in which the freezing point of the mixture of the organic peroxide and the organic peroxide having a freezing point of 0 ° C. or higher is 0 ° C. or lower.

Specific examples of the organic peroxide include, for example, di (n-propyl) peroxydicarbonate, di (isopropyl) peroxydicarbonate, di (sec-butyl) peroxydicarbonate, dicapryloxydicarbonate, di (2-). Peroxydicarbonates such as ethylhexyl) peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate, t-butylperoxy-2-ethylhexanoate, t-butylperoxypivalate, Peroxyesters such as t-butylperoxy neodecanoate, cumylperoxy neodecanoate, dipropionyl peroxide, diisobutyryl peroxide, di (3,5,5-trimethylhexanoyl) peroxy There are diacyl peroxides such as dode.

Further, in the present invention, an organic peroxide diluted with an organic solvent may be used in order to improve the thermal stability of the organic peroxide or to lower the freezing point. For example, there are plasticizers such as benzene, toluene, aliphatic hydrocarbons, dimethyl phthalate and dioctyl phthalate. When used, the content of the organic solvent is within 40% by weight in the aqueous emulsion of the organic peroxide.

The content of the organic peroxide in the aqueous organic peroxide emulsion of the present invention is usually 5 to 80% by weight, and if it is too small, the transportation cost becomes high, which is not economically preferable.
Practically preferable is 10 to 65% by weight.

(c) Freezing point depressant As the freezing point depressant used in the present invention, all those which have been used for the purpose of the freezing point depressant in the aqueous emulsion of the organic peroxide can be used. And especially lower alcohols are preferred. For example, methyl alcohol, ethyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin is contained. Usually, it is 2 to 30% by weight.

(d) Protective colloid agent The protective colloid agent used in the present invention includes, for example, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, water-soluble cellulose derivatives such as hydroxyethyl cellulose, partially or completely saponified polyvinyl acetate,
It is polyvinylpyrrolidone. The type and amount of the protective colloid agent is appropriately selected depending on the type of organic peroxide and the desired viscosity of the resulting aqueous emulsified organic peroxide,
Its content lies substantially in the range from 0.1 to 10% by weight.

Further, it may be one kind or a mixture of two or more kinds.

The protective colloid agent is used for the purpose of increasing the storage stability of the aqueous emulsified organic peroxide. However, if one prefers a low viscosity so that it can be transferred easily, no protective colloid agent is added.

The aqueous emulsified organic peroxide of the present invention is produced by a known method. Specifically, all the usual methods for producing an aqueous emulsion can be used, but normally, a partially saponified polyvinyl acetate and a freezing point depressant are dissolved or dispersed in an aqueous phase, while an oil phase is used as an interface with an organic peroxide. Dissolve or disperse the activator. Then, the oil phase is mixed with the water phase. Further, emulsify with a homogenizer. The thus obtained product has excellent stability and safety because it contains water as a continuous phase.

The aqueous organic peroxide emulsion of the present invention may contain, in addition to the above-mentioned components, an inorganic salt such as sodium chloride to the extent that storage stability is not affected.

For producing the aqueous emulsified organic peroxide of the present invention, for example, paddle type, propeller type, turbine type mechanical rotary agitator, colloid mill, homogenizer, high-speed shearing device, line mixer, ultrasonic homogenizer, etc. Known devices can be used. An extremely stable emulsion can be obtained by using these devices to prepare an emulsion having an average particle size of 10 μm or less.

The aqueous emulsified organic peroxide of the present invention is useful as a suspension polymerization or copolymerization initiator for ethylenically unsaturated monomers. Applicable monomers include vinyl halides such as vinyl chloride, vinyl halide monomers such as vinylidene halide, vinyl ethers, esters of acrylic acid or methacrylic acid, aromatic vinyls such as styrene, maleic acid or fumaric acid. Examples thereof include acid esters, ethylene and vinyl acetate. And vinyl chloride is particularly preferred.

During suspension polymerization, for example, water, a dispersion aid and the above-mentioned monomer are charged into a polymerization vessel, and then an aqueous emulsified organic peroxide is charged, and the mixture is polymerized by performing stirring and heating operations to obtain excellent quality. A polymer is obtained. As a method of charging the aqueous emulsified organic peroxide, there is a method of diluting it with water to an appropriate viscosity and then pumping it. At that time, the amount of the aqueous emulsified organic peroxide used is within the usual range of use.

<Effect of the Invention> The aqueous emulsified organic peroxide of the present invention has various advantages. First, even if the production conditions of the raw materials and the emulsification conditions are changed to some extent, it is possible to obtain the prepared products with excellent stability. One of the reasons is that the particle size distribution in the emulsion is narrower than in the past. Secondly, if it is placed under conditions where slight vibrations are applied for a long time, the viscosity does not drop significantly and the two layers do not separate, so that handling and transportation during use can be extremely facilitated. Third
Moreover, even if it is separated, it can be easily returned to the original uniform state by redispersion. These effects are greater than those of the conventional ones, especially when the oil content in the aqueous emulsion is as high as 50% by weight or more.

When it is used as a polymerization initiator for suspension polymerization or copolymerization of an ethylenically unsaturated monomer, it can be handled more easily and safely than conventional polymerization initiators.

<Examples> Next, examples and comparative examples will be described, but they are merely examples and the present invention is not limited thereto.

Examples-1 to 8 and Comparative Examples-1 to 4 Aqueous emulsified organic peroxide having a composition as shown in Table 1 was produced as follows.

First, water, a freezing point depressant and a protective colloid agent were put into a 500 ml three-necked flask equipped with a propeller impeller type stirrer and a thermometer. After dissolution, the solution was cooled to obtain an aqueous solution at about 10 ° C. On the other hand, the solution obtained by mixing the nonionic surfactant and the organic peroxide was dropped into the aqueous solution with stirring. When stirring was continued for 30 minutes after dropping, a milky white aqueous emulsified organic peroxide could be obtained.

The symbols in the table have the following meanings.

STO: sorbitol fatty acid ester, STA: sorbitan fatty acid ester, SB: sorbide fatty acid ester.

In addition, the types of fatty acids in the table indicate the names of the fatty acids that are the main components. For example, the nonionic surfactant of the number a is prepared from a fatty acid containing 70% by weight of oleic acid.

Using this as a sample, the following stability test, viscosity measurement, vibration test and polymerization test were carried out.

[Stability Test] The sample was placed in a glass container kept at −15 ° C., sampled from the upper layer and the lower layer of the glass container little by little over time, and the content of organic peroxide was measured by an iodometry method. The number of days until the difference in the content of the organic peroxide between the upper layer and the lower layer was 10% or more was defined as the stable period. The result is the second
Shown in the table.

[Viscosity measurement] The viscosity was measured immediately after the production and after the vibration test. That is, immediately after production, the viscosity of the sample at 0 ° C. was measured using a B-type viscometer (manufactured by Tokyo Keiki Seisakusho, rotational speed: 20 RPM). Then, under a condition of -15 ° C, about 300 g of the sample was vibrated for 5 hours by a vibration device (Micromixer MT, Taiyo Kagaku Kogyo Co., Ltd.), and then the viscosity was measured. The results are shown in Table 2.

Table 2 shows that the aqueous emulsified organic peroxide of the present invention has excellent static stability, and that the difference in viscosity between immediately after the production and after the vibration test is small, and that the comparative examples are static. It shows that the stability is poor and that it is weak against vibration.

[Polymerization test] A polymerization test of vinyl chloride was carried out as follows using the aqueous emulsified organic peroxide of the present invention shown in Examples-1 to 8 as a polymerization initiator. That is, 0.45% by weight of polyvinyl alcohol, 300 parts by weight of water and 100 parts by weight of vinyl chloride and a third
Put the amount of aqueous emulsified organic peroxide shown in the table into the autoclave, and heat with stirring to 58 ℃,
The reaction was continued until the polymerization reaction was completed. The polymer obtained therefrom was filtered and dried to obtain white powdery polyvinyl chloride. The yield is shown in Table 3.

Table 3 shows that polyvinyl chloride can be safely synthesized in a high yield by carrying out a polymerization reaction using the polymerization initiator according to the present invention.

Claims (2)

[Claims] 1. Sorbitol, sorbitan and sorbite are fatty acid esters having 10 to 22 carbon atoms, and the content of sorbitol fatty acid ester, sorbitan fatty acid ester and sorbite fatty acid ester is 1% by weight, respectively.
-30% by weight, 42-90% by weight, 3-50% by weight, 0.1-10% by weight of a nonionic surfactant having a hydroxyl value of 60-230, and 5-5% of an organic peroxide. 8
An aqueous emulsified organic peroxide containing 0% by weight, 2 to 30% by weight of a freezing point depressant, or 0.1 to 10% by weight of a protective colloid as a substantial main component. 2. A polymerization initiator for suspension polymerization or copolymerization of an ethylenically unsaturated monomer comprising the aqueous emulsified organic peroxide of claim 1.