JPH0372641B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for suspension polymerization of vinyl chloride-based unsaturated monomers, and more specifically, to a method for suspension polymerization of vinyl chloride-based unsaturated monomers, and more specifically, to a method for using a water emulsion of an organic peroxide containing a specific emulsifier and having excellent stability over time and safety as a polymerization initiator. The present invention relates to a method for suspension polymerization of vinyl chloride-based unsaturated monomers, which yields polymers with excellent electrical insulation properties. Polyvinyl chloride polymers are widely used as insulating materials for electric wires and other electrical parts. In order to be used as an electrically insulating material, it is very important to increase the electrical insulation properties and volume resistivity as much as possible. Furthermore, in recent years, polymerization equipment has been developed to improve productivity when producing polyvinyl chloride polymers and to prevent environmental pollution caused by the toxicity of residual and waste vinyl chloride unsaturated monomers. This is done by increasing the size of the polymerization system, making the production system automatic and continuous, and making the entire polymerization reaction system closed. Suspension polymerization of vinyl chloride-based unsaturated monomers usually involves the use of protective colloids and/or emulsifiers to obtain a polymer with a desired particle size, and the use of a polymerization initiator to cause the polymerization reaction. It is done by twisting. However, when these additives are used, it is known that the properties of the polymer product, such as volume resistivity, are adversely affected depending on the type of the additive. Currently, radical polymerization initiators active at low temperatures are mainly used as polymerization initiators for vinyl chloride unsaturated monomers in order to improve productivity through cycle up. Such polymerization initiators are mainly organic peroxides such as peroxydicarbonates, peroxyesters, and diacyl peroxides, which are generally highly reactive, unstable, and highly dangerous substances. These polymerization initiators are undesirable from the viewpoints of handling, safety, and toxicity. Therefore, in recent years, water emulsions or suspensions of organic peroxides that can be used even in closed systems have been proposed. For example, use a solid organic peroxide as the polymerization initiator suspension, and use a nonionic emulsifier with an HLB value greater than 15 and a polyoxyethylene group that does not contain a cyclic internal ether bond. The method used (Japanese Unexamined Patent Publication No. 110703/1983), a nonionic emulsifier with an HLB value greater than 15 and having a polyoxyethylene group, and an HLB
A method using an emulsifying system consisting of a nonionic emulsifier having a value smaller than 9 and having no polyoxyethylene group, and the HLB value of the mixed emulsifier is in the range of 11 to 17 (Japanese Patent Application Laid-Open No. 110702-1982) Publication No.) etc. Also, organic peroxides, emulsifiers and/or protective colloids containing alkanols having 1 to 4 carbon atoms and/or alkanediols having 2 to 4 carbon atoms and which are liquid at -5°C. A method using a water emulsion consisting of (JP-A-56-139509) has been disclosed. However, these methods have several drawbacks as described below. For example, in the first method using a water suspension obtained from a solid organic peroxide, if the water suspension adheres or remains inside the container or piping, the highly pure organic peroxide is produced by evaporation of the water. Automatic transportation using pumps is not recommended, as the danger increases as the substances tend to precipitate, and furthermore, it is extremely difficult to remove precipitated organic peroxides, and the removal operation involves considerable risk. There are drawbacks that make it unsuitable for preparation. Furthermore, the method of obtaining a liquid organic peroxide-in-water emulsion using an emulsifier used in a solid organic peroxide-in-water suspension has the disadvantage that a sufficiently stable emulsion cannot be obtained. Furthermore, when the next method using a water emulsion of a liquid organic peroxide was tested, the electrical properties of the obtained polymer were significantly impaired, and it could not be used as an electrically insulating material. The present inventors conducted research in search of a method for solving the above-mentioned drawbacks and providing a polymer with excellent safety and stability as well as excellent electrical properties. and HLB value is 4~
When 10 emulsifiers or two or more emulsifiers are combined, the HLB value of the resulting mixed emulsifier is 4 to 10.
A water emulsion of a specific organic peroxide obtained using a mixed emulsifier that is The present invention was completed based on the knowledge that polymers have excellent electrical properties. That is, the method of the present invention uses an organic peroxide having a freezing point of 0°C or lower and a 10-hour half-life of 75°C or lower, a water-soluble alcohol with a molecular weight of 100 or lower as an anti-caking agent, and water. , at least one nonionic type that does not contain polyoxyethylene groups and has an HLB value of 4 to 10 for itself in the case of a single emulsifier, or for a mixed emulsifier in the case of two or more types. This method is characterized in that a vinyl chloride unsaturated monomer is subjected to suspension polymerization using a water emulsion of an organic peroxide obtained by adding an emulsifier as a polymerization initiator. The method of the present invention relates to the polymerization of vinyl chloride-based unsaturated monomers, and can be applied not only to homopolymerization of vinyl chloride but also to copolymerization mainly consisting of vinyl chloride. In this case, comonomers to be copolymerized with vinyl chloride include vinyl esters, vinyl ethers, esters of acrylic acid or methacrylic acid, α-olein, aromatic vinyl, vinyl halides other than vinyl chloride, vinylidene halides, maleic acid, Examples include fumaric acid esters, which are generally used in an amount of 30% by weight or less when mixed with vinyl chloride. The water emulsion of organic peroxide used in the suspension polymerization of the present invention is prepared by using an emulsifier and a molecular weight of
This can be carried out by adding an aqueous solution obtained by dissolving a water-soluble alcohol of 100 or less in water to an organic peroxide while stirring, or by adding an organic peroxide to the aqueous solution. At this time, the emulsifier can also be used after being dissolved in an organic peroxide. The organic peroxide water emulsion thus obtained has water as a continuous phase, and therefore exhibits excellent properties in terms of safety and stability. Furthermore, such water emulsions of organic peroxides have excellent storage and transportability at low temperatures due to the anti-caking effect of the water-soluble alcohol. The organic peroxide used in the present invention has a 10-hour half-life temperature of 75°C or lower and a freezing point of 0.
One or more organic peroxides having a temperature below ℃. Further, the present invention also includes a mixed organic peroxide having a freezing point of 0°C or lower, which is a mixture of the organic peroxide and an organic peroxide having a freezing point of 0°C or higher.
The temperature that shows a half-life of 10 hours here means approximately 0.1
When the organic peroxide concentration is increased to 0.2 mol/2 and held at a certain temperature, it takes 10 hours for the original organic peroxide to decompose and the amount of active oxygen to be reduced to 1/2. It means a temperature like that. Specifically, the organic peroxides include di(n-propyl)peroxydicarbonate, di(isopropyl)peroxydicarbonate, di(Sec-butyl)peroxydicarbonate, di(capryl)peroxydicarbonate, and dicarbonate. (2
-ethylhexyl) peroxydicarbonate,
peroxydicarbonates such as di(2-ethoxyethyl)peroxydicarbonate and di(methoxyisopropyl)peroxydicarbonate;
t-Butylperoxyneodecanoate, cumylperoxyneodecanoate, t-butylperoxypivalate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t- Peroxy esters such as butyl peroxy-2-ethylhexanoate, diacetyl peroxide, dipropionyl peroxide, diisobutyryl peroxide,
Examples include diacyl peroxides such as di(3,3,5-trimethylhexanoyl) peroxide, and mixed organic peroxides include, for example, a mixture of di(2-ethylhexyl) peroxydicarbonate and acetylcyclohexylsulfonyl peroxide. In the present invention, a solvent may be added in order to make the organic peroxide more stable or to lower its freezing point. In the organic peroxide water emulsion used in the present invention, the content of the organic peroxide is usually
The content is 10 to 65% by weight, but if it is too low, transportation costs will be high and it is economically unfavorable, and if it is too high, it will be difficult to obtain a product with excellent safety. The remainder is water, an emulsifier, and a water-soluble alcohol with a molecular weight of 100 or less. The water-soluble alcohol with a molecular weight of 100 or less used in the present invention refers to a low-molecular-weight alcohol that dissolves in water in any proportion, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and ethylene glycol. , glycerin, etc. Low-molecular-weight water-soluble alcohols have traditionally been considered undesirable solvents because they significantly reduce the storage stability of organic peroxides. Emulsions of organic peroxides in water do not impair the stability of the organic peroxides. The amount of the water-soluble alcohol used is within the range of 0.02 to 7 parts by weight per 1 part by weight of water, because if the amount is too small, the degree of freezing point depression will be small, and if it is too large, the organic peroxide will become unstable.
At this time, the water-soluble alcohols may be used in combination of two or more thereof. The nonionic emulsifier used in the water emulsion of organic peroxide used in the suspension polymerization of the present invention must not contain a polyoxyethylene group as a hydrophilic group in its molecule. In particular, sorbitan monoesters, sorbitan diesters and sorbitan triesters of lauric, palmitic, stearic or oleic acids and sutucarose monoesters, sutucarose diesters of lauric, palmitic, stearic or oleic acids. and satsuka roast triester. As a commercially available product of the above-mentioned sorbitan mono-, di- and triester, for example, the product name: Nonion LP manufactured by Nippon Oil & Fats Co., Ltd.
-20R, PP-40R, SP-60R, OP-80R,
There are the same OP-83RAT and the same OP-85R. In addition, examples of the above-mentioned sutucarose mono-, di- and triester include ryotosugar ester S-370, S-770, S-1170, S-
1670, P-1670, LWA-1540, OWA-
1570 etc. The emulsifier has a HLB value of 4
It is also possible to combine two or more types so that the number is ~10. If the HLB value is less than 4 or more than 10,
It becomes difficult to obtain a water emulsion of organic peroxide with good storage stability. Considering the economic efficiency and the influence on the quality of the obtained polymer, it is preferable to use the minimum amount of the nonionic emulsifier necessary to obtain a stable water emulsion. It is within the range of 0.005 to 0.1 parts by weight. The HLB value is the hydrophilic-lipophilic balance as described in "Surfactant Handbook" Kogaku Tosho Co., Ltd. edition (1977) co-edited by Takahashi, Namba, Koike, and Kobayashi of Nippon Oil & Fats Co., Ltd. It should be understood that As described in the above publication, the above-mentioned HLB value can be determined by a simple calculation formula for various nonionic emulsifiers, and when two or more emulsifiers are used in combination. can be calculated from the weight ratio of each component. The organic peroxide water emulsion used in the present invention has a relatively low viscosity, making it easy to handle and pumpable.
The viscosity should not exceed 50 poise at 20°C, and generally less than 20 poise is preferred. And the water emulsions are very stable and, after relatively long storage periods, do not exhibit any kind of phase separation that cannot be used for polymerization. Incorporating substances in the water emulsion that function as thickeners and/or protective colloids in order to prevent that the organic peroxide in the water emulsion can no longer be homogeneously distributed in the continuous phase in the event of phase separation. That is appropriate. These substances are preferably used in amounts that prevent phase separation to the maximum possible extent. Examples of suitable substances for this purpose are synthetic and natural polymers, which may be partially hydrolyzed, such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and combinations with acrylic amides or acrylic esters. acrylic acid copolymers, water-soluble cellulose derivatives such as hydroxyethyl and hydroxypropyl cellulose,
These include methylcellulose and carboxymethylcellulose, gelatin, and starch. The amount of protective colloid is appropriately selected depending on the desired viscosity of the water emulsion, emulsifier and organic peroxide. The amount used is 0.001 to 0.5 per 1 part by weight of water.
within the range of parts by weight, preferably within the range of 0.005 to 0.1 parts by weight. Among these, polyvinyl alcohol or water-soluble cellulose derivatives are preferably used. A well-known apparatus can be used to produce the water emulsion of organic peroxide used in the suspension polymerization of the present invention. For example, paddle type,
It is a propeller-type or turbine-type mechanical rotating stirrer, and a colloid mill, homogenizer, high-speed shear emulsifier, ultrasonic homogenizer, etc. can also be used. The method of the present invention can be carried out in accordance with the conventional method of polymerizing vinyl chloride in an aqueous medium, except that the water emulsion of the organic peroxide described above is used as a polymerization initiator. Conventionally known agents may be used in appropriate amounts, and there are no particular limitations. Since the method of the present invention is configured as described above, it has several advantages as shown below. First, because polyvinyl chloride polymers with excellent electrical properties can be obtained, products obtained from the same batch can be used for a variety of purposes, and large-scale polymerization equipment allows mass production of a wide variety of products. It becomes possible. Second, since the water emulsion can be stored cooled to below 0° C. without condensation, deterioration of the organic peroxide can be prevented, and it can be automatically charged into polymerization equipment in its original form. Thirdly, the water emulsion has excellent safety because the organic peroxide and water are emulsified in a preferable state. For example, there is no severe self-accelerating decomposition or violent combustion upon ignition, which occurs with ordinary radical polymerization initiators, and there is no storage,
It can be handled and transported extremely safely. Therefore, damage caused by backflow of vinyl chloride that sometimes occurs when a polymerization initiator is charged after vinyl chloride is charged into the polymerization equipment can be minimized. Fourth, the water emulsion is a low viscosity liquid and can be easily diluted with water, so it is suitable for metering the required amount, pumping and/or pressurized transportation. Furthermore, if it adheres or remains inside the container or piping, it can be easily washed away with water. Next, Examples, Reference Examples, Comparative Examples, and Comparative Polymerization Examples will be given and explained, but all are for illustrative purposes and the present invention is not limited to them. [Reference and Comparative Examples of Organic Peroxide Water Emulsions] Reference Example 1 A 500 ml three-necked flask equipped with a stirrer and a thermometer was charged with a diluted liquid having a freezing point of -50°C or less and a 10-hour half-life of 43.5°C. 40 parts by weight of (2-ethylhexyl) peroxydicarbonate were added and the bath temperature was raised to 20°C. 43 parts by weight of water, 12 parts by weight of methyl alcohol, 2 parts by weight of polyvinyl alcohol, and 1.5 parts by weight of sorbitan monolaurate (product name: Nonion LP-20R, HLB8.6, manufactured by NOF Corporation) ) and 1.5 parts by weight of sorbitan monooleate (trade name: Nonion OP-80R, HLB4.3; manufactured by NOF Corporation), the HLB value of the mixed emulsifier is 6.5.
A mixed solution of was added dropwise while stirring. After dripping, 20
After stirring continuously for several minutes, the viscosity reached 20℃.
A homogeneous and stable opalescent organic peroxide water emulsion of 1.3 poise was obtained. This sample was heated at −15℃
A storage stability test was conducted for one month by placing the sample in a container kept at a constant temperature, and it was found that the sample was stable with no decrease in organic peroxide content or change in shape. Furthermore, the obtained water emulsion of organic peroxide was tested according to the safety test described below, and the results are shown in Table 1. Comparative Example 1 Instead of using sorbitan monolaurate and sorbitan monooleate as emulsifiers,
Polyoxyethylene monostearate with HLB value of 18.2 (product name: Nonion S-40, NOF Corporation)
A water emulsion of organic peroxide was produced according to Reference Example 1, except that 3 parts by weight of 3 parts by weight of the product (manufactured by J.D. Ta. However, when we conducted a storage stability test at -15℃,
The mixture was separated by standing overnight. Thus, it has been found that a sufficiently stable water emulsion of an organic peroxide cannot be obtained when an emulsifier other than those defined by the present invention is used. Comparative Example 2 Instead of using sorbitan monolaurate and sorbitan monooleate as emulsifiers,
Polyoxyethylene monostearate with HLB value of 18.2 (product name: Nonion S-40, NOF Corporation)
Sorbitan monostearate (trade name: Nonion SP-60R,
Except for using a mixed solution with an HLB value of 16 of a mixed emulsifier consisting of 0.4 parts by weight of Nippon Oil & Fats Co., Ltd.
A water emulsion of organic peroxide was produced according to Reference Example 1. As a result, a homogeneous milky-white water emulsion of organic peroxide with a viscosity of 1.3 poise at 20°C was obtained, but when a storage stability test was conducted at -15°C, it was found that by standing overnight, separated. As described above, when mixed emulsifiers other than those defined by the present invention were used, a sufficiently stable water emulsion of organic peroxide could not be obtained. Comparative Example 3 Instead of using sorbitan monolaurate and sorbitan monooleate as emulsifiers,
An organic peroxide water emulsion was produced according to Reference Example 1, except that 3 parts by weight of sorbitan trioleate (trade name: Nonion OP-85R, manufactured by NOF Corporation) with an HLB value of 1.8 was used. Viscosity is 20
A homogeneous opalescent organic peroxide water emulsion of 1.3 poise at °C was obtained. However, when a storage stability test at -15°C was carried out, the product separated after being allowed to stand overnight. Thus, it was found that when emulsification was performed using an emulsifier with an HLB value of less than 4, a stable water emulsion of organic peroxide could not be obtained. Reference Examples 2 to 3 20 parts by weight of peroxydicarbonate were prepared according to Reference Example 1, except that 15 parts by weight of di(2-ethylhexyl) peroxydicarbonate was used in Reference Example 2, and 90 parts by weight was used in Reference Example 3. When water emulsions of organic peroxide containing % and 60% by weight were produced, uniform milky white organic peroxide water emulsions were obtained in each reference example, and the viscosity at 20°C was that of reference example 2. The value obtained in Example 3 was 1.0 poise, and that of Reference Example 3 was 5.9 poise. Next, the following safety tests were conducted using the water emulsions of organic peroxides obtained in Reference Examples 1 to 3. The results are shown in Table 1. [Safety Test] The water emulsions of organic peroxides obtained in Reference Examples 1 to 3 were subjected to a combustion test and a rapid heating test according to the following procedure, and the results are shown in Table 1. Combustion test A combustion test was conducted using a Cleveland open flash point tester specified in JIS-K2274-62 to determine ignition and ignition temperatures, and the combustion state was observed. Safety evaluations based on combustion tests were classified using the following symbols. ○ mark: Ignition and ignition temperature is 70℃ or higher, combustion condition is mild. △ mark: The ignition and ignition temperature is 66 to 70°C, and the combustion state is somewhat violent. Rapid heating test A thermal stability test was conducted in accordance with the rapid heating test method of OPPPSD (abbreviation for Organic Peroxide Producer Safety Division) to determine the temperature at which it begins to rise rapidly and the maximum temperature reached. . Stability evaluation by rapid heating test was classified using the following symbols. ○ mark: Maximum temperature reached is 100℃ or less △ mark: Maximum temperature reached 100 to 130℃

[Examples and comparative polymerization examples of suspension polymerization of vinyl chloride-based unsaturated monomers]

Examples 1-6, Comparative Examples 4-5, and Comparative Polymerization Examples 1-
2. Place 0.45 parts by weight of polyvinyl alcohol, 300 parts by weight of water, 100 parts by weight of vinyl chloride, and the water emulsion of the organic peroxide obtained in Reference Examples 1 to 6 in the amounts shown in Table 2 into an autoclave. ,
The mixture was heated to 58° C. with stirring, and the reaction was continued for 8 hours until the polymerization reaction was completed. after that,
When the obtained polymer was dried separately, white powdery polyvinyl chloride was obtained in the yield shown in Table 2. To 100 g of each obtained polyvinyl chloride,
50g of dioctyl phthalate and 8g of tribasic lead sulfate
The resulting mixture was rolled for 10 minutes and then pressed into plates at 160°C.
Next, the volume resistivity of each was measured based on JIS-K6911 "General Test Methods for Thermosetting Plastics", and the results are shown in Table 2. For comparison, 0.03 parts by weight of 99% pure di(2-ethylhexyl) peroxydicarbonate (Comparative Example 4) was used as a polymerization initiator, or polyoxyethylene nonyl with an HLB of 9.5 was used as one of the conventional emulsifiers. Suspension polymerization of vinyl chloride was carried out according to Examples 1 to 6 using 0.075 parts by weight of the organic peroxide water emulsion (Comparative Example 5) obtained according to Reference Example 1, except that 3 parts by weight of phenol ether was used. The yield and volume resistivity were determined, and the results are shown in Table 2 as Comparative Polymerization Examples 1 and 2, respectively.

[Table] As is clear from Examples 1 to 6 and Comparative Polymerization Example 1 in Table 2, additives such as emulsifiers and anti-caking agents used in the method of the present invention affect the yield of polyvinyl chloride and It was found that there was no effect on the volume resistivity. Moreover, Examples 1 to 6
As is clear from Comparative Polymerization Example 2, it can be seen that the method of the present invention provides polyvinyl chloride with superior electrical properties as compared to the conventional method. Example 7 Examples 1 to 6 except that 90 parts by weight of vinyl chloride and 10 parts by weight of vinylidene chloride were used instead of vinyl chloride as the vinyl chloride-based unsaturated monomer.
Suspension polymerization of vinyl chloride-based unsaturated monomers was carried out according to . As a result, vinyl chloride was produced with a yield of 81%.
A vinylidene chloride copolymer was obtained, which had a volume resistivity of 92×10 ¹⁰ ohm·m. Comparative Polymerization Example 3 Comparative Polymerization Example 2 except that 90 parts by weight of vinyl chloride and 10 parts by weight of vinylidene chloride were used instead of vinyl chloride as the vinyl chloride-based unsaturated monomer.
Suspension polymerization of vinyl chloride-based unsaturated monomers was carried out according to . As a result, vinyl chloride was produced with a yield of 80%.
A vinylidene chloride copolymer was obtained, which had a volume resistivity of 19×10 ¹⁰ ohm·m. As is clear from a comparison between Example 7 and Comparative Polymerization Example 3, the method of the present invention provides a vinyl chloride-vinylidene chloride copolymer with superior electrical properties compared to the conventional method. Ta.

Claims (1)

[Scope of Claims] 1. At least one organic peroxide selected from the group consisting of peroxydicarbonates, peroxyesters, and diacyl peroxides having a freezing point of 0°C or lower and a 10-hour half-life temperature of 75°C or lower. 10 to 65% by weight, the balance consisting of water, emulsifiers and water-soluble alcohols, which may further contain thickeners and/or protective colloids, (a) where the emulsifier is lauric acid, palmitic acid, stearic acid or oleic acid; One or more selected from the group consisting of sorbitan monoester, sorbitan diester, and sorbitan triester of acids, and sutucarose monoester, sutucarose diester, and sutucarose triester of lauric acid, palmitic acid, stearic acid, or oleic acid. , the HLB value for a single emulsifier or for a mixed emulsifier in the case of two or more emulsifiers is 4 to 4.
10, which contains 0.005 to 0.1 part by weight per 1 part by weight of water; (b) the water-soluble alcohol is a water-soluble alcohol with a molecular weight of 100 or less; (c) Use a water emulsion organic peroxide as a polymerization initiator, containing 0.02 to 7 parts by weight per 1 part by weight of water, and (c) having a viscosity not exceeding 50 poise at 20°C. A method for suspension polymerization of vinyl chloride-based unsaturated monomers, characterized by: 2 The water-soluble alcohol is one or more selected from the group consisting of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol, and glycerin, and the vinyl chloride unsaturated monomer is chlorinated. A method for suspension polymerization of a vinyl chloride-based unsaturated monomer according to claim 1, which is vinyl.