JPH01188507A - Production of block copolymer and polymerization initiator - Google Patents

Abstract

PURPOSE:To obtain a block copolymer useful as a binder, surface-treating agent, etc., on an industrial scale at a low cost, by using a ketone peroxide having a specific structure as a radical polymerization initiator and carrying out the polymerization by a two-stage polymerization process. CONSTITUTION:The objective block copolymer is produced by using a polymerization initiator consisting of methyl isobutyl ketone peroxide containing >=70% of the organic peroxide of formula and carrying out the polymerization by two-stage polymerization process. The two-stage polymerization process preferably comprises the 1st stage polymerization of one or more monomers at a low temperature in the presence of a reducing agent acting exclusively to hydroperoxy group and inducing redox reaction (e.g., sodium bisulfite or L- ascorbic acid) and the successive 2nd stage polymerization comprising the addition of one or more monomers to the polymerization system maintained at a high temperature to induce the decomposition of the monomer.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an improved method for producing a block copolymer by a two-step polymerization method using a ketone peroxide having a specific structure as a radical polymerization initiator, and a method for polymerization. Regarding initiators.

[Conventional technology]

In recent years, there has been an increasing demand for polymeric compounds that can exhibit high functionality, and for this reason, not only high molecular weight polymers, but also graft copolymers and block copolymers are becoming increasingly important. . Significant progress has been made in increasing the molecular weight of polymers by using poly(2)-functional organic peroxides as radical polymerization initiators, and it has become possible to control the molecular weight to a certain extent. I can say it.

It can be said that even in the production of graft copolymers, industrial objectives have been achieved through the use of organic peroxides with a high hydrogen abstraction ability, which have been devised based on experience. on the other hand,
Regarding the production of block copolymers, many techniques have been published to date.

[Problem to be solved by the invention]

However, with the exception of radical polymerization technology (other methods are very interesting from an academic point of view, they currently have too many difficulties to be implemented industrially. However, it must be said that its practical value is still low from the perspective of industrialization.Needless to say, the application range of block copolymers is extremely wide, and the physical properties of polymers by so-called polymer blends are very limited. It is expected that this block copolymer will be used in a wide variety of fields, including the modification of block copolymers and the improvement of coating resins, and there is an urgent need to establish a simple industrial production technology for this block copolymer.

[Means to solve the problem]

The present inventors have proposed a polymerization technique for easily obtaining a block copolymer with a higher molecular weight than conventionally obtained polymers, and the viewpoint of the mechanism of action of organic peroxides as radical polymerization initiators. As a result of extensive research, it was discovered that ketone peroxide having a specific molecular structure effectively provides a block copolymer, and the present invention was completed.

The present invention contains 70% of the specific compound represented by the general formula (■).
Using the above-containing methyl isobutyl ketone peroxide, a two-stage polymerization method is used: first, in the first stage polymerization, no.
At least one monomer is polymerized at low temperature in the presence of a reducing agent that acts only on idrobaroxy groups to cause a redox reaction, and then as a second stage polymerization,
The present invention provides an improved method for producing a block copolymer and a polymerization initiator by newly adding and polymerizing at least one monomer at a high decomposition temperature.

CH3C)J13CI(3C1,13I HC-CI(2-C-OC)-C-CH,-CH(1)
.

CI (300HOOHCI (3 [Type 3]) CI (3CI4 HC-CI C-00H (II), HOOH (I
II) CI (300I-I [Type 4]) By the way, methyl isobutyl ketone peroxide is
Along with methyl ethyl ketone peroxide, etc., it has been widely used as a curing agent for unsaturated polyester resins, and is a compound with a structure represented by the general formula (1) (usually referred to as type 3), and a compound represented by (II). Compounds with structure (
It is usually referred to as Type 4), and (III) and exists as a mixed composition containing filtered hydrogen oxide as a main component, and compositions containing less than 70% of Type 3 are commonly used. The present invention is characterized in that a block copolymer can be advantageously produced by using methyl isobutyl ketone peroxide containing 70% or more of type 3 (1) as a radical polymerization initiator. These 3 types, 4.7fJ
Methylinobutylketone peroxide compositions with different content ratios of li can be obtained by conventional synthesis methods, but in particular, the composition of the present invention containing type 3 as a main component can be obtained using the method described in U.S. Pat. No. 40,524.65. It can be easily synthesized according to the method described in Examples 5 and 6.

For example, 38.9 g (0.8 mol) of 70% hydrogen peroxide solution, 30 ml of benzene, 5 ml of methyl in butyl ketone,
0 g (0,5 mol) and p-toluenesulfonic acid (2
111 g (equivalent to 1 mole ketone) and mixed for 15 minutes, then cooled and maintained the temperature at 20°C. After the addition is complete, about 20 g of water are removed from the reaction mixture by azeotropic distillation under reduced pressure at 30°C. Then 40 mt of water is added and the pH of the mixture is adjusted to about 5 by a solution of 2N-hydroxide).
Adjust to 5. Xylene 31. g to the organic layer;
Benzene is removed by vacuum distillation. As a result, 80 g of a methyl isobutyl ketone peroxide solution having a total oxygen content (A○) of 13.1% is obtained. This solution is about 70
% contains 3 plastic components (thin layer chromatography)
.

The resulting solution can be used as is, but
Furthermore, as a result of treatment with an aqueous sulfide solution accompanied by water washing at 15° C. and dilution with 19 g of xylene, 90 g of a methyl isobutyl ketone peroxide solution containing 95% of AO content and 94% of 3 plastic components is obtained.

Furthermore, if the synthesis conditions are further selected, it is also possible to synthesize methyl isobutyl ketone peroxide consisting of almost only three types, that is, general formula (1). The organic peroxide of the present invention is in liquid form, and is usually commercially available diluted to a safe active oxygen concentration.

A feature of the present invention is a method for producing a block copolymer using methyl isobutyl ketone peroxide represented by general formula (1) and employing a two-step polymerization method. That is,
The first stage polymerization is redox polymerization, which promotes the decomposition of the two hydroperoxy groups (-00H') in general formula (1), but reduces the dialkyl peroxy group (-00-), which is difficult to decompose. In the second stage polymerization, a block copolymer is produced by initiating polymerization in combination with a new monomer. Therefore, the production process of the block copolymer is as follows.

CH3CH3CH3CH3 HC-CI-(2-C-QC)-C-CH2-CI-1
-1-R (reducing agent) -1△l II
1CH300HOOHCH3 CH3CH3CH,,CH3 HC-C)J12-C-00-(,CHz -CH+
20H・・・・・・・・・・・・(1) CI-(30・
0. toru CH3CH3CI (3CH3 mountain 0 ratio helmet - HC-CH2-C00CCH2CH・・・・・・・・・
(2) 1 1 1
lCH30-AAA-A 0-A-AA-A CH3
In the production process of CH3CH3(FH3(FH3□)), first in (1) the reducing agent R reacts preferentially with two hydroperoxy groups to create a radical source capable of initiating polymerization, and in (2) this Based on this, monomer A is polymerized.

That is, in the first stage polymerization, a polymer containing a dialkyl type peroxy bond (-00-) in the main chain is produced. Subsequently, heating with force U cleaves this remaining peroxy bond (3)
, polymeric radicals are generated, polymerization of monomer B begins (4), and as a result, it is thought that an AB type block copolymer is produced.

It is desirable that the reducing agent that can be used in the first stage polymerization preferentially decomposes the two hydroperoxy groups of methyl isobutyl ketone peroxide (I), and typical examples include L-ascorbic acid, textulose, Examples include sodium bisulfite, sodium sulfite, sodium thiosulfate, and sodium formaldehyde sulfoxylate. Third-stage amines such as dimethylaniline and organometallic compounds such as cobalt naphthenate, which are commonly used as curing accelerators for unsaturated polyester resins, are
This is not preferred because not only the hydroperoxy group but also the dialkyl type peroxy bond (-00-) is equally decomposed. At least one type of reducing agent is used, and two or more types can be used in combination.

The polymerization method of the present invention is preferably emulsion polymerization or suspension polymerization. Of course, solution or bulk polymerization methods are also possible, and combinations thereof can also be carried out, but since the reducing agent suitable for the first stage polymerization is water-soluble, it is desirable and practical to employ an aqueous polymerization process.

Monomers that can be used are typified by radically polymerizable vinyl and vinylidene compounds. Vinylidene chloride, vinyl chloride, vinyl acetate, acrylic esters such as butyl acrylate, methacrylic esters such as methyl methacrylate, acrylic acid, methacrylic acid, ethylene, propylene, acrylonitrile, methacrylonitrile, styrene, styrene core Examples include substituted derivatives, α-methylstyrene, vinyltoluene, vinylpyrrolidone, phthadiene, divinylbenzene, etc., but are not limited to these. Of course, the monomers that can be used in the first-stage polymerization and the subsequent second-stage polymerization are not only used alone, but also a mixture of two or more monomers that can be copolymerized. do not have.

The polymerization method of the present invention will be explained below by taking emulsion polymerization as an example. First, in the first stage polymerization, deionized water,
A selected monomer (e.g., vinyl chloride) and a specific organic peroxide represented by the general formula (1) are added to a reaction vessel which has been purged with nitrogen and contains an emulsifier and an activator if necessary. Add 0.05-5 parts of the mixture and bring the temperature of the system to 0-65
C., preferably 30 to 60.degree. C., and add an aqueous reducing agent solution.

After the monomer polymerization is completed, the temperature of the system is raised to 70-1
The temperature is maintained at 30°C, preferably 70-120°C, and new monomers to be blocked are added and polymerized. The monomer can be added all at once, in portions, or continuously. In the second stage, polymeric radicals generated by thermal decomposition of peroxy bonds (-00-) bonded and remaining in the main chain of the first stage polymer start polymerization to produce a block copolymer. . The block copolymer latex thus obtained was processed by an appropriate method to form a powder. It was further purified as necessary and used as a sample for analysis or measurement.

〔Effect of the invention〕

The specific organic peroxide of the present invention is usually liquid and easy to handle. By using this organic peroxide,
It becomes possible to easily produce a desired block copolymer industrially, and the obtained block copolymer can be expected to be applied and used in a wide range of fields such as binders, surface treatment agents, and coating agents.

[Example] The present invention will be explained in detail with reference to Examples and Comparative Examples below.
Both parts and % mean parts by weight and % by weight.

Example 1 4000 parts of deionized water and 4 parts of sodium tetratecylbenzenesulfonate as an emulsifier were added to a flask equipped with a stirrer, a thermometer, and a reflux condenser, and the mixture was purged with nitrogen. ) and 1000 parts of methyl methacrylate as a monomer were added and stirred, and the temperature of the system was maintained at 40 to 50°C.

An aqueous solution prepared by dissolving 4 parts of sodium formaldehyde sulfoxylate in 75 parts of water was added to this, and the mixture was reacted for 150 minutes. After the polymerization was completed, 1000 parts of styrene was added, the temperature of the polymerization system was raised to 85 to 90°C, and the reaction was carried out for 180 minutes.

After the reaction was completed, a homogeneous latex-like product was obtained. This latex was salted out with an aqueous calcium chloride solution, washed, filtered, and dried under reduced pressure.

Example 2゜Into the same flask used in Example 1, add 2000 ml of deionized water.
After adding 0.5 parts of sodium pyrophosphate and 3 parts of sodium bisulfite and thoroughly purging with nitrogen, the temperature of the system was maintained at 45 to 50°C, and 500 parts of methyl methacrylate was added to the flask. 1 part, 5 parts of methyl isobutyl ketone peroxide containing 90% of the compound represented by general formula (1), and 2.5 parts of thorium dodecylbenzenesulfonate were continuously added for 100 minutes, and then for an additional 100 minutes. It was kept as it was to complete the polymerization. Next, 500 parts of styrene was added, the temperature of the system was raised to 85 to 90°C, and the reaction was carried out for 170 minutes. The obtained latex-like product was salted out with an aqueous calcium chloride solution, washed, filtered, and then dried under reduced pressure.

Example 3 Styrene was used in the first stage polymerization, and the polymerization temperature was 50 to 55°C.
A latex-like product was obtained by carrying out polymerization according to Example 2, except that methyl methacrylate was used in the second stage polymerization at 80 to 85°C.

Example 4 Add 2,000 parts of deionized water to a reaction vessel, and after thoroughly purging with nitrogen, add 1 part of IJium and 3 parts of sodium formaldehyde sulfoxylate,
A solution prepared by dissolving and mixing 500 parts of methyl methacrylate, 5 parts of methyl isobutyl ketone peroxide containing 90% of the compound represented by general formula (1), and 5 parts of sodium dioctylsulfoconophosphate was kept at 0°C for 110 minutes. It was continuously added dropwise and kept at 45-50°C for an additional 80 minutes. Simultaneously with the addition of the monomer, an aqueous solution prepared by dissolving 1 part of sodium thiosulfate in 100 parts of water was continuously added dropwise for 110 minutes. After polymerization, 500 parts of styrene was added and the temperature of the system was increased to 85-9.
The reaction was completed by keeping at 0°C for 170 minutes. A latex-like product was obtained.

The polymers obtained in Examples 1 to 4 were separated into a block copolymer and each homopolymer by the Soxhlet extraction method using cyclohexane/acetonitrile/benzene, and the blocking efficiency of styrene was 80-80. It was found that the block copolymer of methyl methacrylate and styrene was efficiently produced.

Example 5 Put 2,000 parts of deionized water into a reaction vessel, and after thoroughly purging with nitrogen, add 1 part of sodium pyrophosphate, 1 part of L-ascorbic acid, and 3 parts of dextrose, and add 300 parts of methyl methacrylate to this. A mixed solution of 200 parts of butyl methacrylate, 6 parts of sodium dotecylbenzenesulfonate, and 6 parts of methyl isobutyl ketone peroxide containing 70% of the compound represented by general formula (1) was added to 180 g.
The reaction mixture was continuously added dropwise at a temperature of 45 to 55°C for minutes. Next, a mixture of 200 parts of butyl acrylate and 20 parts of acrylonitrile was added and the temperature was raised to 80-85°C.
The reaction was allowed to proceed for 50 minutes. A latex-like block copolymer was obtained.

Comparative Example 1゜In Example 2, a composition mixture with an abundance ratio of type 3 (])/type 4 (II) of 50150 was used instead of methyl isobutyl ketone peroxide represented by general formula (11), and the other steps were the same. We attempted to produce a block copolymer using the method.

A latex-like product was obtained, but the styrene blocking efficiency was very low at 19%.

Comparative Example 2 An attempt was made to produce a block copolymer using the same process as in Example 2, except that ammonium persulfate was used instead of methyl isobutyl ketone peroxide. However, the second stage polymerization did not proceed and failed.

Comparative Example 3 An attempt was made to produce a block copolymer using the same process as in Example 2, except that cumenohydrobor oxide was used instead of methyl isobutyl ketone peroxide, but styrene polymerization did not proceed. We're screwed.

Patent applicant: Kayaku Nouri Co., Ltd.

Claims (2)

[Claims] (1) A method for producing a block copolymer, which comprises using methyl isobutyl ketone peroxide containing 70% or more of the compound represented by general formula (1) as a polymerization initiator, and employing a two-step polymerization method. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (2) A polymerization initiator for block copolymers, characterized by comprising methyl isobutyl ketone peroxide containing 70% or more of the compound represented by general formula (1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1)