JPH09278816A - Method of polymerization of vinyl monomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a vinyl resin composition which has a high molecular weight with a branched component and contains little low-molecular component by using a free radical initiator comprising a peroxide composition containing structures capable of generating tetra-, di- and monofunctional oxygen radicals at a specified ratio. SOLUTION: A method of the radical addition polymerization of a vinyl monomer, wherein a peroxide composition having a partial structure (a) capable of generating a tetrafunctional oxygen radical represented by formula I (wherein R<1> and R<2> are each a 1-2C alkyl), a partial structure (b) capable of generating a difunctional oxygen radical represented by formula II (wherein R<3> is a 2-16C alkylene) and a partial structure (c) capable of generating a monofunctional oxygen radical represented by formula III (wherein R<4> is a 3-8C alkyl) in a molar ratio of the structures (a) to (b) of (1:0.3) to (1:2) and in a molar ratio of the structures (a) to (c) of (1:0.05) to (1:3.5) is used as a free radical initiator in an amount sufficient to provide an equivalent ratio of the active oxygen to the vinyl monomer of (0.005 to 1.0):100.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for radical addition-polymerizing a vinyl-based monomer. For more details,
The present invention relates to a method for producing a vinyl-based resin composition having a high molecular weight, a branched component and a small amount of a low molecular weight component by the polymerization method with high productivity.

[0002]

2. Description of the Related Art Radical addition polymerization of vinyl monomers is widely carried out industrially due to the variety of monomers that can be used and the polymers obtained. For example, polystyrene,
Used for styrene-acrylonitrile copolymer, polymethylmethacrylate, polyvinyl chloride and the like.

It is well known that it is effective to increase the degree of polymerization of the polymer in the composition in order to increase the strength of a molded article molded from the composition of the resin obtained by these polymerization methods. . In addition, in the case of radical addition polymerization, it is known that it is effective to polymerize at a low temperature in order to increase the degree of polymerization, but at a low temperature, there is a problem that productivity is poor because the polymerization rate is slow. Further, it is effective to use a radical initiator such as a peroxide or an azo compound in order to increase the polymerization rate, but there is a contradiction that the molecular weight of the obtained polymer becomes low when the radical initiator is used.

In order to solve such a problem, a method of using a polymeric peroxide polymer having a repeating unit having a bifunctional oxygen radical structure is disclosed in, for example, JP-A-60.
-8304, JP-A-60-13805, JP-A-4-80211, and the like. On the other hand, four oxygen radicals can be generated in one molecule.
A method of performing polymerization using a functional peroxide has also been known for a long time, and has been proposed in Japanese Examined Patent Publication No. 41-19511.

By the way, it is known that when this type of initiator is used under specific polymerization conditions, not only a high molecular weight is obtained but also a branched component is produced. It is described in JP-A-4-268346 that a resin having a branching component is suitable for foaming applications in polystyrene, for example, and it has not only a high molecular weight but also a branching point. It can be said that the present resin composition is industrially valuable.
However, in the method using the tetrafunctional initiator, a low molecular weight polymer is also produced due to a large amount of monofunctional radicals simultaneously generated. Therefore, as a method of increasing the molecular weight and adding a branching component, a method of copolymerizing a small amount of a difunctional or higher functional monomer such as divinylbenzene has been known for a long time, but this method produces a crosslinked polymer. There is a problem that it does. On the other hand, when a chain transfer agent is used together to prevent crosslinking, low molecular weight components are also produced.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art described above, and is a method capable of efficiently producing a resin composition having a high molecular weight and containing a branched component, and further having a low amount of a low molecular weight component. The challenge is to provide.

[0007]

In the present invention, as a result of extensive studies to solve the above problems, a special radical polymerization initiation containing a tetrafunctional component, a bifunctional component and a monofunctional component in a specific ratio was initiated. By polymerizing using the agent composition,
The inventors have found that all of the above problems can be solved, and have completed the present invention.

That is, the present invention provides a method for producing a resin composition by radical-addition-polymerizing a vinyl-based monomer,
As a radical initiator, (a) a partial structure capable of generating a tetrafunctional oxygen radical represented by the following formula (1),

[0009]

Embedded image (In the formula, R ¹ and R ² each independently have 1 to 2 carbon atoms.
Represents an alkyl group. ) (B) A partial structure capable of generating a bifunctional oxygen radical represented by the following formula (2):

[0010]

Embedded image —OR ³ —O— Chemical formula (2) (wherein, R ³ represents a divalent alkyl group having 2 to 16 carbon atoms) and (c) the following formula (3) And has a partial structure capable of generating a monofunctional oxygen radical, and

[0011]

Embedded image R ⁴ —O —... Chemical formula (3) (In the formula, R ⁴ represents a monovalent alkyl group having 3 to 8 carbon atoms.)

The abundance ratio of (a) and (b) is 1: in molar ratio.
Use a peroxide composition in the range of 0.3 to 1: 2 and the abundance ratio of (a) and (c) in the range of 1: 0.05 to 1: 3.5 by molar ratio. And a method for polymerizing a vinyl-based monomer. Further, it is the above-mentioned polymerization method in which the radical addition polymerization is carried out by solution polymerization or bulk polymerization. Further, the above-mentioned polymerization method, wherein the vinyl-based monomer is styrene or a mixture containing styrene as a main component. In the above-mentioned polymerization method, the vinyl-based monomer is styrene or a mixture containing styrene as a main component, and radical addition polymerization is carried out by solution polymerization or bulk polymerization.

The above radical initiator is added in an amount of 0.005% to 1.
The above-mentioned polymerization method is used in the range of 0%. Further, the ratio of (a) and (b) is in the range of 1: 0.5 to 1: 1.5, and the ratio of (a) and (c) is in the range of 1: 1 to 1: 3. It is a certain polymerization method described above. In the chemical formulas (1) to (3) of the radical initiator, R ¹ and R ² are methyl groups or ethyl groups, and R ³ is 2,5-dimethylhexane-2 represented by the following formula (4). , 5-dioxy and R ⁴ is a t-butyl group.

[0014]

Embedded image

Hereinafter, the present invention will be described in detail. The peroxide composition used in the present invention has a partial structure (a) capable of being cleaved to generate a tetrafunctional oxygen radical and a partial structure (b) capable of being cleaved to generate a bifunctional oxygen radical. Although it has a partial structure (c) capable of generating a functional oxygen radical, it may contain a small amount of a hydroxyl group, an —OOH group, or the like.

The abundance ratio of (a) and (b) is 1: in molar ratio.
It should be in the range of 0.3 to 1: 2, and the abundance ratio of (a) and (c) should be in the range of 1: 0.05 to 1: 3.5 in terms of molar ratio. If the amount of component (b) is less than this ratio, the resulting resin will not easily become high in molecular weight, and if it is too large, the peroxide composition itself will become high in molecular weight, making it difficult to handle, and the resulting resin will tend to gel. I will end up. Further, when the amount of the component (c) is less than this ratio, gelation is likely to occur, and when it is more than the above amount, the amount of the low molecular weight polymer increases and the object of the invention is not achieved. More preferable ratio of (a) and (b) is in the range of 1: 0.5 to 1: 1.5, and ratio of (a) and (c) is in the range of 1: 1 to 1: 3. . The method for producing such a peroxide composition is not particularly limited, but a diketone represented by the following chemical formula (5) corresponding to a tetrafunctional oxygen radical structure:

[0017]

Embedded image (In the formula, R ¹ and R ² each independently have 1 to 2 carbon atoms.
Represents an alkyl group. ) A dihydroperoxide represented by the following chemical formula (6) corresponding to a bifunctional oxygen radical structure:

[0018]

Embedded image HOO—R ³ —OOH Chemical formula (6) (wherein, R ³ represents a divalent alkyl group having 2 to 16 carbon atoms.) The following chemical formula (7) corresponding to a monofunctional radical structure. ) And monohydroperoxide,

[0019]

Embedded image R ⁴ —OOH: Chemical formula (7) (wherein, R ⁴ represents a monovalent alkyl group having 3 to 8 carbon atoms) are mixed in a desired ratio, and in the presence of an acid catalyst. It is obtained by gradually warming while removing water produced. In order to remove water, it is convenient to carry out the reaction in a solvent that is azeotropic with water at a temperature low enough not to decompose the peroxide. Therefore, in addition to the equivalence relationship between the ketone and the peroxide and the incomplete reaction, the hydroxyl group and the —OO
It may include an H group.

Since each partial structure of the peroxide composition obtained by this production method is determined by defining the diketone and hydroperoxide as the raw materials, preferred examples of the raw materials in this method will be described below. Suitable diketones include 2,
2-bis (4-ketocyclohexyl) propane, 2,2
-Bis (4-ketocyclohexyl) butane, and the like.

Suitable dihydroperoxides include 2,5-dimethylhexane 2,5-dihydroperoxide, 2,5-dimethyl-2,5-dihydroperoxyhexyne-3, α, α '. Examples thereof include -bis (hydroperoxy-m-isopropyl) benzene and α, α'-bis (hydroperoxy-p-isopropyl) benzene. Suitable monohydroperoxides include t-butyl hydroperoxide and the like.

The peroxide composition thus obtained is usually a complicated mixture of various condensates, and its composition is a pyrolysis gas chromatograph equipped with a mass spectrometer or an infrared spectrophotometer as a detector, Analytical quantification is possible using high resolution NMR.

As diketone, 1 mol of 2,2-bis (4-ketocyclohexyl) propane, as dihydroperoxide 1 mol of 2,5-dimethylhexane 2,5-dihydroperoxide, and as monohydroperoxide A typical repeating unit when t-butyl hydroperoxide is used at a ratio of 2 mol is represented by the following chemical formula (8).

[0024]

[Chemical 12]

In the present invention, radical addition polymerization is carried out using such a peroxide composition. The amount of the peroxide composition used depends on the molecular weight of the polymer to be obtained and the expected polymerization rate. Will be adjusted accordingly. Generally, the number of active oxygen in the peroxide composition may be converted into oxygen molecules and adjusted with the upper limit being twice the number of chain ends in the polymer to be obtained. In order to obtain a polymer having a molecular weight that is industrially produced as a resin composition, an amount of about 0.005 mol to 1 mol in terms of oxygen molecules is used with respect to 100 mol of a monomer to be polymerized. good.

The vinyl monomers which can be used in the present invention are all vinyl monomers capable of radical addition polymerization, and preferred examples are styrene-based monomers such as styrene, α-methylstyrene and p-methylstyrene, and acrylic monomers. Acids and their derivatives such as esters and amides and nitriles, methacrylic acids and derivatives such as esters and amides and nitriles, conjugated dicarboxylic acids such as maleic acid and itaconic acid and their anhydrides and esters, vinyl halides such as vinyl chloride. Examples thereof include compounds, and of these, styrene and a monomer copolymerizable with styrene are particularly preferable.

The polymerization method may be any of bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization, but the effects of the present invention are more remarkable in bulk polymerization and solution polymerization. Further, any of a batch type, a semi-batch type and a continuous type may be used, but a continuous type is suitable for carrying out the present invention aiming at high productivity. Further, in the case of the continuous type, the reactor may be either a complete mixing type or an extrusion flow type. Or,
A plurality of these may be connected in parallel and / or in series and used.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below by way of examples. The analysis of the molecular weight distribution of the resin was performed by the following method. Measurement solvent: Tetrahydrofuran Sample concentration: 1 gram / liter Measurement temperature: 38 ° C. Column: Tosoh Corp., TSK-gel-GMH-
Three XL connected in series Measuring instrument: manufactured by Tosoh Corp., HLC8020 model Detector: RI detector and LALLS detector Calibration: Standard polystyrene produced by Tosoh Corp. was used. Data processing is the analysis software GPC attached to the above equipment
-Using Lalls (3.04 version), the weight average molecular weight in terms of linear polystyrene, the content rate of components having a molecular weight of 50,000 or less,
The content of components having a molecular weight of 1,000,000 or more and the absolute weight average molecular weight were determined.

[0029]

【Example】

Example 1 2,5-bis (4-ketocyclohexyl) propane was added to 0.6 mol of 2,5-dimethylhexane 2,5
-0.5 mol of dihydroperoxide and 1.4 mol of t-butyl hydroperoxide were mixed in a ratio of 1.4 mol to cause a condensation reaction to obtain a peroxide composition.

90% by weight of styrene and 1 of ethylbenzene
The above peroxide composition is added to a solution of 0% by weight in an amount of 2% by weight.
70 ppm was added to obtain a polymerization stock solution. The above polymerization stock solution was continuously supplied to a completely mixed reactor having a volume of 5 liters at a flow rate of 2.5 liters per hour. Keep the reactor at 142 ° C 1
After 0 hours, the solid content concentration and the molecular weight distribution at the outlet of the reactor were measured. The results are shown in Table 1. In addition, Mw (LS) in the table
Is the weight average value of the absolute molecular weight obtained using the light scattering method,
Mw (RI) is a linear PS-equivalent weight average molecular weight obtained from a calibration curve prepared from a standard sample of linear PS, and its ratio is an index of the degree of branching.

Comparative Example 1 In Example 1, the peroxide is a bifunctional peroxide, 1,1-bis (t-butylperoxy) -3,3.
Polymerization and analysis were carried out in the same manner as in Example 1 except that the amount of 5-trimethylcyclohexane was changed to 300 ppm, the flow rate was changed to 1.67 liters per hour, and the temperature of the reactor was changed to 140 ° C. The results are shown in Table 1.

Comparative Example 2 In Comparative Example 1, the peroxide was changed to 275 ppm of 2,2-bis (4,4 di-t-butylperoxycyclohexyl) propane, which is a tetrafunctional peroxide. Polymerization and analysis were carried out in the same manner as in Comparative Example 1. The results are shown in Table 1.

Example 2 2,5-bis (4-ketocyclohexyl) propane was added to 0.5 mol of 2,5-dimethylhexane 2,5
-0.5 mol of dihydroperoxide and 1.0 mol of t-butyl hydroperoxide were mixed to cause a condensation reaction to obtain a peroxide composition. 270 ppm by weight of the above-mentioned peroxide composition was added to a liquid composed of 90% by weight of styrene and 10% by weight of ethylbenzene to prepare a polymerization stock solution. The above stock solution for polymerization was continuously fed to a completely mixed reactor having a volume of 5 liters at a flow rate of 1.0 liter per hour. After keeping the reactor at 103 ° C. for 24 hours, the solid content concentration and the molecular weight distribution at the reactor outlet were measured. The results are shown in Table 1.

Comparative Example 3 In Example 2, the peroxide was a bifunctional peroxide, 1,1-bis (t-butylperoxy) -3,3.
Polymerization and analysis were carried out in the same manner as in Example 2 except that the amount of 5-trimethylcyclohexane was changed to 300 ppm, the flow rate was changed to 0.83 liter / hour, and the temperature of the reactor was changed to 100 ° C. The results are shown in Table 1.

Comparative Example 4 In Comparative Example 3, the peroxide was changed to 275 ppm of tetrafunctional peroxide, 2,2-bis (4,4di-t-butylperoxycyclohexyl) propane. Polymerization and analysis were carried out in the same manner as in Comparative Example 3. The results are shown in Table 1.

[0036]

[Table 1]

[0037]

INDUSTRIAL APPLICABILITY The polymerization method of the present invention has an effect that it is possible to efficiently produce a resin composition having a high molecular weight, a branched component, and a low molecular weight component.

Claims (7)

[Claims] 1. In a method of radical addition polymerization of a vinyl-based monomer, (a) as a radical initiator: a partial structure capable of generating a tetrafunctional oxygen radical represented by the following chemical formula (1); (In the formula, R ¹ and R ² each independently have 1 to 2 carbon atoms.
Represents an alkyl group. ) (B): 2 Functional oxygen radicals partial structure a may occur, and embedded image -O-R ³ -O- ...... formula (2) (wherein represented by the following chemical formula (2), R ³ Represents a divalent alkyl group having 2 to 16 carbon atoms.) (C): having a partial structure capable of generating a monofunctional oxygen radical represented by the following chemical formula (3), and ⁴ -O- ...... formula (3) in the abundance molar ratio of (a) (b) 1 (wherein, R ⁴ is a monovalent alkyl group having 3 to 8 carbon atoms.): 0 .3 to 1: 2
And a peroxide composition in which the abundance ratio of (a) and (c) is in the range of 1: 0.05 to 1: 3.5 by molar ratio. Method of polymerizing monomers. 2. The polymerization method according to claim 1, wherein the radical addition polymerization is carried out by solution polymerization or bulk polymerization. 3. The polymerization method according to claim 1, wherein the vinyl monomer is styrene or a mixture containing styrene as a main component. 4. The polymerization method according to claim 1, wherein the vinyl-based monomer is styrene or a mixture containing styrene as a main component, and the radical addition polymerization is carried out by solution polymerization or bulk polymerization. 5. The polymerization method according to claim 1, wherein the radical initiator is used in a range of 0.005% to 1.0% in terms of an equivalent ratio of active oxygen to the vinyl monomer. 6. The ratio of (a) to (b) is 1: 0.
The polymerization method according to any one of claims 1 to 5, wherein the polymerization ratio is in the range of 5 to 1: 1.5, and the ratio of (a) to (c) is in the range of 1: 1 to 1: 3. 7. The chemical formulas (1) to (1) of the radical initiator
R ¹ and R ^{2 in} (3) are methyl groups or ethyl groups, R ³ is 2,5-dimethylhexane-2,5-dioxy represented by the following chemical formula (4), and R ⁴ is t- It is a butyl group, The polymerization method in any one of Claims 1-6. Embedded image