JPH0130843B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a radical polymerization initiator, and particularly relates to a styrene monomer in which a styrene monomer or a rubbery polymer is dissolved, among ethylenically unsaturated monomers (hereinafter, both are referred to as styrene monomers). It is used in the polymerization of styrenic monomers) and acrylic monomers, and has good workability in polymerization operations, can perform polymerization reactions in high yields, and has a high average molecular weight. This invention relates to a radical polymerization initiator that can be combined. Among polymers, styrene polymers and acrylic polymers are used in a wide range of applications as molding materials, but in this case, they are required to have increased mechanical strength and thermal strength. [Prior Art] Many studies have been made to meet these requirements. For example, in order to obtain a styrene polymer with a high average molecular weight in a method for producing a styrenic polymer, two peroxy groups are added in the molecule instead of t-butylperoxybenzoate, which is a normal monofunctional radical polymerization initiator. This is a method in which peroxide containing a 100% peroxide is used as a radical polymerization initiator. JP-A-48-55981 discloses a method for producing a styrenic polymer with a high average molecular weight using 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; In the publication, 1,1-di(t-butylperoxy)-3,3,
A method using 5-trimethylcyclohexane is
JP-A-52-151383 discloses a method using di(t-butylperoxy)isophthalate. [Problems to be Solved by the Invention] However, each of the above-mentioned bifunctional peroxides has the following problems. In other words, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane is not only solid at room temperature, but also resistant to styrene and acrylic monomers and aromatic hydrocarbon solvents used during polymerization. It has low solubility, and during polymerization operations, it is necessary to dissolve it in a large amount of monomer or solvent and charge it into the polymerization reaction tank, a large capacity polymerization initiator preparation tank is required, and a large amount of solvent may enter the polymerization system. The problem is that the quality of the polymer that is produced is deteriorated. Also, 1,1-di(t-butylperoxy)-3,
3,5-Trimethylcyclohexane has a low 10-hour half-life temperature of 90°C, and its thermal decomposition rate is fast, so if it is polymerized at the same temperature as the other bifunctional peroxides mentioned above, a high molecular weight polymer cannot be obtained. It is a point. Furthermore, di(t-butylperoxy)isophthalate has a high active oxygen content of 10.31%, and in its pure state, there are problems with handling safety, such as rapid decomposition due to friction or impact. In view of the above-mentioned problems, the present inventors conducted long-term research and found that the m
Peroxides with a specific structure in which each position is substituted with an alkyl group have high solubility in styrene and acrylic monomers and aromatic hydrocarbon solvents, and have good workability. The present invention was completed after discovering that a polymer can be obtained in high yield, a polymer with a high average molecular weight, and that it is highly safe to handle. [Means and effects for solving the problems] That is, the present invention has the following general formula: (In the formula, R represents a straight chain alkyl group or a branched alkyl group having 1 to 4 carbon atoms.) A radical polymerization initiator containing a compound represented by the following as an active ingredient. The substitution position of the alkyl group on the aromatic ring has a large effect on the solubility and thermal decomposition rate of peroxides. O
When substituted at the P position, the 10-hour half-life temperature decreases by about 8 degrees, and when substituted at the P position, solubility is not improved. Only those substituted at the m-position do not have a 10-hour half-life temperature drop and exhibit increased solubility. Furthermore, if the number of carbon atoms in the alkyl group exceeds 4, the amount of active oxygen in the peroxide decreases, making it necessary to increase the amount added during polymerization, which is not preferable. Specifically, the above-mentioned peroxides having a specific structure include 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, 2,5-dimethyl-2,5-di(3-ethylbenzoylperoxy) ) hexane, 2,5-dimethyl-2,5-
di(3-n-propylbenzoylperoxy)hexane, 2,5-dimethyl-2,5-di(3-isopropylbenzoylperoxy)hexane,
2,5-dimethyl-2,5-di(3-n-butylbenzoylperoxy)hexane, 2,5-dimethyl-2,5-di(3-isobutylbenzoylperoxy)hexane, 2,5-dimethyl-2, 5
-di(3-sec-butylbenzoylperoxy)
Hexane, 2,5-dimethyl-2,5-di(3-
tert-butylbenzoylperoxy)hexane. The peroxide represented by the above general formula of the present invention is produced by a general method for producing peroxyesters. That is, 2,5-dimethylhexane-
It is produced in a yield of 80 to 90 mol% by reacting 2,5-dihydroperoxide and 3-alkylbenzoyl chloride at 0 to 30°C. This peroxide can be confirmed and quantified by infrared absorption spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis, and measurement of the amount of active oxygen by iodometry. The radical polymerization initiator of the present invention can be used as a polymerization initiator for general ethylenic monomers and a curing agent for unsaturated polyester resins, but in particular, it can be used as a radical polymerization initiator for styrene and acrylic monomers. preferred as Rubbery polymers used for the styrene monomer in which a rubbery polymer is dissolved in a styrene monomer include, for example, polybutadiene, copolymers of butadiene and styrene, acrylonitrile, methyl methacrylate, etc. Examples include natural rubber and ethylene-propylene copolymer.
The ratio of the rubbery polymer to the styrene monomer is usually 1 to 20% by weight based on the styrene monomer.
This is the percentage of The reasons why the above monomers are particularly preferable are that the general polymerization temperature of the above monomers and the temperature at which the peroxide of the present invention is used are almost the same, so that the polymerization reaction can be carried out efficiently, and that polymers with a high average molecular weight can be used. This is because union can be obtained. The method of using the radical polymerization initiator of the present invention is t-
It may be substantially the same as butylperoxybenzoate or 2,5-dimethyl-2,5-di(benzoylperoxy)hexane. That is, the operating temperature is 70 to 180℃,
Preferably it is 90-160°C. A temperature lower than 70° C. is undesirable because the decomposition rate becomes extremely slow and it takes a long time to complete the polymerization, or a large amount of peroxide remains in the polymer. Also 180℃
As the peroxide rapidly decomposes when it exceeds
This is undesirable as it makes it impossible to control the polymerization reaction. The amount used is usually 0.01 to 2% by weight, preferably 0.02 to 0.5% by weight, based on the monomer. If it is less than 0.01% by weight, the polymerization rate becomes extremely slow, which is not preferable. Moreover, if it exceeds 2% by weight, the polymerization reaction will occur rapidly and temperature control will become difficult, which is undesirable. Further, the polymerization initiator of the present invention may be used alone or in combination of two or more, and furthermore, other general polymerization initiators such as dibenzoyl peroxide and di-t
-Butyl peroxide etc. may be used in combination. The radical polymerization initiator of the present invention can be used by known general polymerization methods such as bulk polymerization, suspension polymerization, and solution polymerization, as well as by four-part polymerization methods, continuous polymerization methods, and the like. [Effects of the Invention] (1) Since the peroxide with a specific structure of the present invention has high solubility in styrene-based and acrylic-based monomers and aromatic hydrocarbon-based solvents, workability such as preparing a polymerization initiator liquid during polymerization is improved. Excellent. (2) Long-term handling and storage is possible in the form of a highly concentrated polymerization initiator solution. (3) General formula known polymerization method used for t-butyl peroxybenzoate etc. (Modern
Plastics, Vol. 51, pp. 69-71 (1974))
It can be applied directly to the conditions described above, and the polymer can be obtained in high yield. (4) A polymer having a high average molecular weight can be obtained. [Examples], [Reference Examples], and [Comparative Examples] The present invention will be specifically explained below with reference to Examples, Reference Examples, and Comparative Examples. Example 1 [Synthesis of 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane] 10% by weight of sodium hydroxide was placed in a 4-neck flask with an internal volume of 1 equipped with a stirrer and a thermometer. aqueous solution
Add 240.0g (0.6mol) and then add purity while stirring.
57.6 g (0.25 mol) of 77.4% by weight hydrated powder of 2,5-dimethyl-2,5-dihydroperoxyhexane was added. Next, the temperature of the reaction liquid in the flask is
While keeping the temperature at 20℃ and stirring vigorously, add 92.8 g (0.5 mol) of 3-methylbenzoyl chloride for 20 minutes.
It was administered within minutes. Stirring was then continued for 1 hour.
The white crystals formed were separated, pre-cleaned twice with 300 ml of water, filtered and dried under reduced pressure in a desiccator.
When the weight was measured after reaching a constant weight, it was 91.2 g. The infrared absorption spectrum of this white crystal
Measured by KBr pellet method. As a result, carbonyl group absorption was observed at 1750 cm ^-1 and weak peroxy bond absorption was observed at 800 cm ^-1 . Elemental analysis was performed using a sample of the white crystals recrystallized in methanol, and the results showed that carbon was 69.71% by weight, hydrogen was 7.25% by weight, and oxygen was calculated to be 23.04% by weight. Theoretical value is 69.54% by weight of carbon, hydrogen
7.30% by weight and 23.16% by weight of oxygen. The amount of active oxygen determined by iodometry was 7.68%. From the above results, it was confirmed that this white crystal was 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane. Table 1 also shows the 10-hour half-life temperature of this peroxyester in benzene (temperature when the time required for the concentration to be reduced to half is 10 hours) and the solubility in styrene monomer, toluene, and ethylbenzene. Examples 2-3 3-isopropylbenzoyl chloride in place of 3-methylbenzoyl chloride, respectively
2,5-dimethyl-2,
5-di(3-isopropylbenzoylperoxy)hexane and 2,5-dimethyl-2,5-di(3-t-butylbenzoylperoxy)hexane were synthesized. In addition, the 10-hour half-life temperature and solubility in styrene monomer, toluene, and methyl methacrylate were also measured. The results are shown in Table 1.

[Synthesis of 2,5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane diluted with ethylbenzene]

20% by weight aqueous potassium hydroxide solution in a 4-necked flask with an internal volume of 2 equipped with a stirrer and a thermometer.
Add 358.4g (1.3mol) and then add purity while stirring.
115.1 g (0.5 mol) of 77.4% by weight hydrated powder of 2,5-dimethyl-2,5-dihydroperoxyhexane was added. Next, add 240g of ethylbenzene,
While maintaining the temperature of the reaction solution at 25° C., 154.6 g (1.0 mol) of 3-methylbenzoyl chloride was added dropwise over 30 minutes with vigorous stirring. Stirring was then continued for 1 hour. The aqueous phase is then separated in a separatory funnel,
The organic phase was washed with a 3% by weight aqueous sodium hydroxide solution, once with 1 portion of water, and then dried over anhydrous magnesium sulfate. This was separated to obtain 403.2 g of a colorless and transparent liquid. As a result of measuring the infrared absorption spectrum of this liquid, carbonyl group absorption was observed at 1750 cm ^-1 . The amount of active oxygen determined by iodometry was 3.61%. From the above, this liquid has a purity of 46.3% by weight, 2,5-dimethyl-2,5-
This is a solution of di(3-methylbenzoylperoxy)hexane in ethylbenzene. Reference Example 1 [Polymerization of styrene monomer] Put 100 ml of ion-exchanged water, 0.4 g of tribasic calcium phosphate, and 0.0002 g of sodium dodecylbenzenesulfonate into a 500 ml glass autoclave equipped with a stirrer and a thermometer, and add nitrogen gas. I made a replacement. Next, 80 g of styrene monomer was added. After heating in an oil bath and raising the liquid temperature to 110°C, Example 4
2,5-dimethyl-2,5-di(3-
0.35 g of an ethylbenzene solution of methylbenzoylperoxy)hexane (0.2% by weight based on pure content vs. styrene monomer) was pressurized with nitrogen gas. After continuing the reaction for 10 hours, the mixture was cooled to room temperature, and the resulting white bead-like solids were separated, washed twice with 500 ml of water, and then dried under reduced pressure. The yield of the obtained styrene polymer was 77.8
It was hot at g. The intrinsic viscosity of this styrene polymer in benzene at 25°C is 1.20 (average molecular weight 325,000)
It was hot. Reference Example 2 [Polymerization of methyl methacrylate] In a 500 ml four-necked flask equipped with a stirrer, thermometer, Dimroth condenser, and nitrogen gas inlet tube, 0.04 g of sodium lauryl sulfate and 0.53 g of sodium polyacrylate as a suspended powder were added. g and sodium sulfate
1.62 g of 2,5-dimethyl-2,5-di(3-isopropylbenzoylperoxy) hexane synthesized in Example 2 was added to 100 g of methyl methacrylate dissolved in 200 ml of ion-exchanged water. A solution containing 0.1 g of pure product was added and stirred vigorously. The temperature was raised to 90°C in a hot water bath, and then maintained at 90°C by cooling. After 3 hours, the mixture was cooled to room temperature, and the resulting white bead-like solids were washed with 300 ml of water and dried under reduced pressure. The weight of the obtained polymethyl methacrylate was 94.8 g. The intrinsic viscosity of this product in benzene at 25°C was 0.66 (average molecular weight 233,000). Comparative Examples 1 to 3 Benzoyl chloride, 2-methylbenzoyl chloride and 4-methylbenzoyl chloride were used as acid chlorides, respectively.
2,5-dimethyl-
2,5-di(benzoylperoxy)hexane,
2,5-dimethyl-2,5-di(2-methylbenzoylperoxy)hexane and 2,5-dimethyl-2,5-di(4-methylbenzoylperoxy)hexane were synthesized, and the 10-hour half-life temperature and Solubility was measured. The results are shown in Table 1. Comparative Example 4 Styrene monomer was polymerized in the same manner as in Reference Example 1, except that 0.16 g of t-butyl peroxybenzoate (0.2% by weight of styrene monomer in terms of purity) was used as a radical polymerization initiator. Ta. The yield of the obtained styrene polymer was 78.2 g, and the intrinsic viscosity in benzene at 25°C was 0.98 (average molecular weight
247300). Comparative Example 5 Styrene monomer was prepared in the same manner as in Reference Example 1, except that 0.18 g (90% purity) of 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane was used as a radical polymerization initiator. Polymerization of polymers was carried out. The weight of the obtained styrene polymer was 78.8 g. The intrinsic viscosity of this product in benzene at 25°C was 1.03 (average molecular weight 264,400).

Claims (1)

[Claims] 1. General formula (In the formula, R represents a straight-chain alkyl group or a branched alkyl group having 1 to 4 carbon atoms.) A radical polymerization initiator containing a compound represented by the following as an active ingredient.