JPH08109213A - Aqueous organic peroxide emulsion - Google Patents

Abstract

PURPOSE: To obtain an aqueous organic peroxide emulsion which does not undergo demulsification for a long term at room temperature and is excellent in storage stability and safety. CONSTITUTION: This emulsion is one comprising an organic peroxide, water, a surfactant and a protective colloid. The organic peroxide is one having a 10-hr half-life temperature of 80 deg.C or above and being liquid at room temperature and is used in an amount of 10-40 pts.wt. The surfactant is used in an amount of 0.01-10 pts.wt. The protective colloid comprises a partially swaponified polyvinyl acetate of a degree of saponification of 70-90mol% and an average degree of polymerization of 300-1500 and is used in an amount of 0.1-10 pts.wt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerization initiator for vinyl monomers, and more particularly to an aqueous emulsion of an organic peroxide suitable as a polymerization initiator in emulsion polymerization of vinyl monomers. More specifically, the present invention relates to an aqueous organic peroxide emulsion which has good storage (static) stability at room temperature (normal temperature), is safe, and is easy to handle.

[0002]

2. Description of the Related Art In recent years, in producing various polymers by bulk polymerization, suspension polymerization and emulsion polymerization of vinyl monomers, enlargement, continuation and automation of polymerization equipment have been promoted for the purpose of improving productivity. Came. As a polymerization initiator suitable for this purpose, organic peroxide that has been diluted with an organic solvent or emulsified with water has been easy to handle and has excellent safety. It has been put to practical use because continuous automation is possible by sending liquid. For example, as an organic solvent diluted product, an organic peroxide diluted to a desired concentration with various organic solvents is commercialized according to its purpose of use, and is widely used in the bulk polymerization and suspension polymerization fields of various vinyl monomers. Has been. Further, in the field of suspension polymerization of vinyl chloride-based monomers, protection of organic peroxides having a 10-hour half-life temperature of 80 ° C or lower, freezing point depressants such as water and methanol, surfactants, and polyvinyl acetate Aqueous emulsions of organic peroxides composed of colloid agents have been proposed and widely used (JP-A-56-139).
509, JP 61-130315, JP 62-86005, JP 1-249132).

[0003]

However, the diluted organic peroxide in an organic solvent and the aqueous emulsion of the organic peroxide each have the following drawbacks, and particularly, a polymerization initiator in the emulsion polymerization of vinyl monomers. Is unsuitable as That is, the organic solvent diluted product, when it is used as a polymerization initiator, a large amount of organic solvent is introduced into the polymerization system, the organic solvent acts as a chain transfer agent or a polymerization terminator and desired emulsion polymerization. I can't achieve it. Also in the case of the above-mentioned aqueous emulsion, alcohols such as methanol, which is a freezing point depressant, are introduced into the polymerization system, and the desired emulsion polymerization cannot be achieved as in the case of the above diluted organic solvent product. Furthermore, the organic peroxide used in the aqueous emulsion is a so-called low temperature active organic peroxide having a 10-hour half-life temperature of 80 ° C. or lower. Therefore, handling and storage at room temperature (normal temperature) may cause quality deterioration and eventually explosion and decomposition, which requires refrigerated (frozen) storage, which is inconvenient because of certain facility restrictions on handling and storage.

[0004]

Means for Solving the Problems The present inventors have found that an aqueous emulsion of an organic peroxide that has solved the above-mentioned drawbacks of the prior art, that is, does not contain an organic solvent that may adversely affect the polymerization reaction, and is at room temperature The present invention has been completed as a result of intensive research aimed at developing an aqueous emulsion of an organic peroxide that can be handled and stored in (1), is safe, and has excellent storage stability. That is, the present invention relates to an aqueous organic peroxide emulsion comprising an organic peroxide, water, a surfactant and a protective colloid agent, which has a 10-hour half-life temperature of 80 ° C. or higher and is liquid at room temperature. 10-40 parts by weight, surfactant 0.
01 to 10 parts by weight and a saponification degree of 7 as a protective colloid agent
0 mol% to 90 mol% and an average degree of polymerization of 30
It relates to an aqueous emulsion of an organic peroxide containing 0.1 to 10 parts by weight of partially saponified polyvinyl acetate of 0 to 1500.

The organic peroxide used in the aqueous organic peroxide emulsion of the present invention has a 10-hour half-life temperature of 8
It is liquid at 0 ° C or higher and at room temperature. The reason is that the so-called low-temperature activated organic peroxide having a 10-hour half-life temperature of less than 80 ° C has a risk of quality deterioration and eventually explosive decomposition when handled or stored at room temperature (room temperature), as described above. In some cases, automation cannot be performed safely. Further, if it is solid at room temperature, it is difficult to form an aqueous emulsion, and neither of them can achieve the object of the present invention. And as an organic peroxide which satisfies the above-mentioned conditions and the aqueous emulsion is more preferable as an initiator for emulsion polymerization of vinyl monomers, for example, t-butylperoxyisopropyl carbonate, t-butylperoxy-n-butylcarbonate, t- Butyl peroxy-2-ethylhexyl carbonate, t-amyl peroxyisopropyl carbonate, t-hexyl peroxyisopropyl carbonate, 1,1,3,3-tetramethylbutylperoxyisopropyl carbonate, 1-cyclohexyl-1-methylethylperoxyisopropyl carbonate, etc. Peroxycarbonates, t-butyl hydroperoxide, t-amyl hydroperoxide, t-hexyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroper Kishido, cumene hydroperoxide, di -
Hydroperoxides such as isopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1-cyclohexyl-1-methylethylhydroperoxide, t-butylperoxybenzoate, t-butylperoxylaurate, t-butylperoxy-3,5,5.
Examples thereof include peroxyesters such as 5-trimethylhexanoate, t-amylperoxybenzoate, and t-hexylperoxybenzoate.

The protective colloid agent used in the present invention is a partially saponified polyvinyl acetate having a saponification degree of 70 to 90 mol% and an average degree of polymerization of 300 to 1500. These include acid-modified partially saponified polyvinyl acetate obtained by saponifying a copolymer of vinyl acetate and methacrylic acid or acrylic acid. For example, L-580 manufactured by Unitika Chemical Co., Ltd., B-05 manufactured by Denki Kagaku Kogyo Co., Ltd.
K-05, MP-10, Gohsenol GM-14 manufactured by Nippon Synthetic Chemical Industry Co., Ltd., L-8, KL manufactured by Kuraray Co., Ltd.
-506 etc. are mentioned. Other than the protective colloid agent in the present invention, there are the following drawbacks. That is, when the degree of saponification is small, the emulsion has poor storage stability and is difficult to dissolve in water. On the contrary, when the degree of saponification is large, the storage stability of the emulsion becomes poor. When the average degree of polymerization is low, the viscosity of the aqueous emulsion is low, but the storage stability tends to be poor. On the contrary, when the average degree of polymerization is large, the storage stability is improved, but there is a drawback that the viscosity is too high.

The type and amount of the partially saponified polyvinyl acetate is appropriately selected depending on the type of organic peroxide and the desired viscosity of the emulsion. It may also be a mixture of two or more.
The content of the organic peroxide in the aqueous emulsion is usually 0.1 to 10% by weight, and if it is too small, the storage stability becomes poor, and if it is too large, it is economically disadvantageous, and therefore, preferably 1 to 10.
8% by weight.

The surfactants used in the present invention are anionic surfactants and nonionic surfactants. Examples of the anionic surfactant include fatty acid soaps, alkyl sulfates, sodium alkylbenzene sulfonates and sodium dialkylsulfosuccinates. Examples of nonionic surfactants include fatty acid sorbitan esters and fatty acid polyglycol esters. The type is appropriately selected depending on the type of organic peroxide. It is used in one kind or a mixture of two or more kinds. The content is usually 0.01 to 10% by weight in the aqueous emulsion of organic peroxide. If it is too much or too little, the storage stability will deteriorate, so it is preferably 0.1
It is 7% by weight.

In the aqueous organic peroxide emulsion of the present invention, the content of the organic peroxide is 5 to 40 parts by weight, and if it is too small, a large amount is added to the polymerization system in practical use, resulting in workability. Is caused, which is not preferable. If it exceeds 40 parts by weight, sufficient safety cannot be ensured and the object of the present invention cannot be achieved. Practically preferred range is 10
40 parts by weight.

In the aqueous emulsion of the organic peroxide of the present invention, in the polymerization using the same, an organic solvent may be mixed in such an amount that does not cause abnormal polymerization such as chain transfer action or polymerization termination action.

The aqueous emulsion of organic peroxide of the present invention is produced by a known method. Specifically, all methods for producing an ordinary aqueous emulsion can be used, but usually, a partially saponified polyvinyl acetate and a surfactant are dissolved or dispersed in an aqueous phase, and an organic peroxide is mixed therein,
Emulsify with a homogenizer. Examples of devices that can be used at this time include paddle-type, propeller-type, turbine-type instrument rotary agitators, colloid mills, homogenizers,
A high speed shearing device, a line mixer, an ultrasonic homogenizer and the like can be mentioned.

The organic peroxide aqueous emulsion of the present invention is useful as a radical polymerization initiator for vinyl monomers, and particularly, styrene / butadiene copolymer, acrylonitrile / butadiene / styrene copolymer, methyl methacrylate / It is suitable as an initiator for emulsion polymerization of butadiene / styrene copolymer, acrylonitrile / vinyl chloride copolymer and the like.

[0013]

The organic peroxide aqueous emulsion of the present invention does not separate at room temperature (normal temperature) for a long period of time and is excellent in safety. Therefore, it is easy to handle, and bulk transportation by lorries and continuous automation by storage and pumping are possible, which can contribute to productivity improvement. Further, the organic peroxide aqueous emulsion of the present invention is composed of an organic peroxide, water, a surfactant and a protective colloid agent, and does not contain an organic solvent or the like that may adversely affect the polymerization reaction. It can be more suitably used as a polymerization initiator for the body.

[0014]

The present invention will be described below in more detail with reference to examples and comparative examples. (Production of Aqueous Emulsion of Organic Peroxide) Examples 1 to 13 Aqueous emulsions of organic peroxides of the present invention having various compositions shown in Table 1 were produced by the following method. A predetermined amount of water, partially saponified polyvinyl acetate and a surfactant were put into a 500 ml four-necked flask equipped with an ordinary stirrer and a thermometer and dissolved, and then the internal temperature was adjusted to 20 to 25 ° C. The organic peroxide was added dropwise thereto, and the mixture was vigorously stirred. The mixture was further stirred for 30 minutes to obtain an aqueous organic peroxide emulsion. Comparative Examples 1 to 7 Aqueous emulsions of various compositions other than the present invention shown in Table 1 were produced in the same manner as in Examples.

The comparative examples are outside the scope of the present invention in the following points. Comparative Example 1 The degree of saponification of partially saponified polyvinyl acetate is high. Comparative example 2 is small. The degree of polymerization of Comparative Example 3 is small. The polymerization degree of Comparative Example 4 is large. Comparative Example 5 Does not contain partially saponified polyvinyl acetate. Comparative Example 6 No surfactant was contained. Comparative Example 7 Too much surfactant.

[0016]

[Table 1]

Next, the following storage stability test, average particle size test and viscosity measurement were carried out using the organic peroxide aqueous emulsions shown in Examples and Comparative Examples. (Storage stability test) 35 g of 100 g of aqueous emulsion
Put it in a glass container of mφ × 100 mm, store it in a constant temperature bath at 20 ° C. and visually check for phase separation.
The concentrations of the organic peroxides in the upper layer and the lower layer of the emulsion were measured by the iodometry method, and the storage stability was judged according to the standard based on the difference. ○: 1 month or more, △: 1 week or more, less than 1 month,
X: less than 1 week, x: no emulsification (average particle size test) The average particle size was measured with a centrifugal particle size analyzer (manufactured by Shimadzu Corporation). (Viscosity measurement) The sample viscosity at 20 ° C was measured using a B-type viscometer (manufactured by Tokyo Keiki Seisakusho Co., Ltd.). The respective results are shown in (Table 2).

[0018]

[Table 2]

(Polymerization test) 2510 g of ion-exchanged water and 66.7 g of potassium fatty acid soap were charged in a nitrogen-substituted 5 liter autoclave, and the soap was dissolved by stirring. 22.3 g of the aqueous emulsion of organic peroxide obtained in Example 3 was charged, and the mixture was stirred at 70
Polymerization was carried out at 10 ° C for 10 hours and 90 ° C for 3 hours. Next, the unreacted monomer was removed to obtain the desired SBR latex. The polymerization conversion rate was 95%.

Claims (1)

[Claims] 1. An aqueous organic peroxide emulsion comprising an organic peroxide, water, a surfactant and a protective colloid agent, which has a 10-hour half-life temperature of 80 ° C. or higher and is liquid at room temperature. 10 to 40 parts by weight of a surfactant, 0.01 to 10 parts by weight of a surfactant, and a partially saponified polyvinyl acetate having a saponification degree of 70 to 90 mol% as a protective colloid agent and an average degree of polymerization of 300 to 1500. 0.1-
Aqueous emulsion of organic peroxide containing 10 parts by weight.