JPH0621124B2 - Method for producing porous copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a porous copolymer, and more specifically, a porous copolymer having a highly developed specific surface area and pore volume. The present invention relates to a manufacturing method of.

[Conventional technology]

Conventionally, among non-polar or slightly polar spherical cross-linked copolymers, those that have sufficiently developed specific surface area and pore volume are
It is called a synthetic adsorbent and is widely used as an adsorbent for organic substances existing in water by utilizing its physical adsorption on the surface of pores.

Methods for producing such synthetic adsorbents are known, for example, suspension polymerization of a mixture of a monovinyl compound, a polyvinyl compound and a porosifying agent in water, and then removing the porosifying agent from the obtained cross-linked copolymer. There is a method, and as the porosifying agent, an organic solvent, a plasticizer, a linear polymer, or a mixture thereof is used. However, the specific surface area and pore volume of the cross-linked copolymer obtained by such a conventional method are not always sufficient, and improvement thereof is desired.

[Object of the Invention]

An object of the present invention is to provide a method for producing a porous copolymer having improved specific surface area and pore volume by improving the conventional method.

[Structure of Invention]

Therefore, an object of the present invention is to prepare a mixture of a porosifying agent consisting of a monovinyl compound, a polyvinyl compound and an aromatic organic solvent and a mixture thereof in water in the presence of 5 to 10% by weight of a polymerization initiator based on all monomers. It can be easily achieved by suspension-polymerizing to obtain a porous crosslinked copolymer, then subjecting the porous crosslinked copolymer to heat treatment and removing the porosifying agent comprising an aromatic organic solvent.

Examples of the monovinyl compound constituting the spherical crosslinked copolymer include aromatic monovinyl monomers such as styrene, vinyltoluene, vinylnaphthalene and ethylvinylbenzene, monovinylheterocyclic compounds such as vinylpyridine, methacrylic acid, acrylic acid and Monovinyl compounds such as their esters, acrylonitrile and methacrylonitrile are useful.

Examples of the polyvinyl compound include polyvinyl aromatic compounds such as divinylbenzene, trivinylbenzene, divinyltoluene, and divinylxylene, polyvinyl heterocyclic compounds such as divinylpyridine, and polyvinyl ester compounds such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. A compound having two or more double bonds active in radical polymerization is useful.

The mixing ratio of these monovinyl compounds may be changed at any ratio, but the ratio of the polyvinyl compound as a crosslinking agent to the total vinyl compounds is 8 to 80% by weight, preferably 15 to
It is selected in the range of 60% by weight.

When the amount of the polyvinyl compound and the polyvinyl compound is less than 8% by weight, the degree of porosity of the crosslinked copolymer is low and the effect of the present invention is difficult to be exhibited.

As the porosifying agent, an organic solvent, a plasticizer and a linear polymer are used. Specifically, aromatic compounds such as toluene and benzene, ester compounds such as ethyl acetate and butyl acetate, isoamyl alcohol and methyl isobutyl are used. Alcohols such as carbinol, saturated hydrocarbons such as n-heptane and isooctane, halogenated solvents such as dichloroethane and trichlorethylene, plasticizers such as dioctyl phthalate and dibutyl adipate, polymers such as polystyrene and polyvinyl acetate. Is useful.

The proportion of the porosifying agent used is 50 to 250% by weight based on the total amount of monomers when an organic solvent and a plasticizer are used, and 1 to 20 relative to the total amount of monomers when a linear polymer is used. Use by weight percent.

The mixture of the monovinyl compound, the polyvinyl compound and the porosifying agent is suspension polymerized by a known method. At that time, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, ozobisisobutyronitrile or the like is used as a polymerization initiator, and usually about 0.1 to 1% by weight based on all monomers. To be However, in the present invention, 3 to 12% by weight, preferably 5 to 10% by weight is used. When it is less than 3% by weight, it becomes difficult to achieve the object of the present invention, and when it is more than 12% by weight, heat generation of radical decomposition is so much that polymerization control becomes difficult and the molecular weight becomes small, which is preferable. Absent.
This suspension polymerization is usually 1-5 per volume of the monomer mixture.
It is carried out by adding a volume of water and heating in the presence of a suspension stabilizer. As the suspension stabilizer, known ones such as gelatin, methyl cellulose, sodium polyacrylate polyvinyl alcohol and the like can be used. The temperature and time of polymerization vary depending on the type of polymerization initiator used, but in the present invention, 10 to 90% by weight of the polymerization initiator used at the end of the polymerization,
It is desirable to carry out the polymerization under the condition that 30 to 70% by weight remains.

After the completion of the polymerization, the polymer is washed with water, and then the porosifying agent remaining in the polymer is removed according to a known method. With this method, the porosifying agent in the polymer decreases. , The polymer shrinks, and the double bond of the side chain of the polyvinyl compound remaining in the polymer at that time causes thermal crosslinking, resulting in irreversible shrinkage of the polymer, resulting in deterioration of the physical properties of the pores. .

The present invention is characterized in that the crosslinked copolymer is heated prior to the removal of the porosifying agent in order to prevent such deterioration of the physical properties of the pores. The purpose of this heat treatment is to eliminate the residual double bond by thermal decomposition of the remaining polymerization initiator without removing the organic solvent for the porosifying agent contained in the polymer to the outside of the system. For this purpose, in the present invention, as described above, unlike the conventional method, the heating of a large amount of the polymer can be carried out independently from the copolymer by separating the copolymer from the polymerization system. It is preferable to carry out under conditions where the agent does not dissipate as much as possible, specifically, in an organic solvent or water. In particular, it is suitable to carry out in water.

The heating is preferably carried out under conditions such that the amount of the polymerization initiator remaining at the end of heating is 1% or less of the used polymerization initiator, and generally heating is performed at 90 to 120 ° C. for 2 to 8 hours. Recommended.

The cross-linked copolymer which has been subjected to the heat treatment, the porosifying agent is removed, but the removal can be performed according to a known method. For example, when an organic solvent is used as the porosifying agent, a solvent is used. It can be carried out by washing, azeotropic distillation or the like. When a plasticizer or linear polystyrene is used, it can be carried out by solvent extraction. The crosslinked copolymer without the porosifying agent is washed with water and, if necessary, with an organic solvent such as alcohol and then used.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example-1 97 g of divinylbenzene having a purity of 56.7% and styrene 3
g, 150 g of toluene and 7 g of benzoyl peroxide were suspended in 75 m containing 1.25 g of polyvinyl alcohol, and the suspension was heated and stirred under nitrogen at 80 ° C. for 8 hours to give a straight diameter of 0.5 to 0.5 A copolymer having a particle size of 1.0 mm was obtained. This polymer was washed with water and washed with water 60
It was added to 0 m and heat treated at 100 ° C. for 6 hours. Next, the cross-linked copolymer was separated, added to 600 m of water, and heated at 89 ° C. under atmospheric pressure to distill off residual toluene. The resulting copolymer is then dried,
The yield and the physical properties of pores were measured. The results are shown in Table-1.

Comparative Example-1 (example without heat treatment in water) In Example-1, except that heat treatment is not performed in water,
The same treatment as in Example-1 was carried out to obtain a copolymer. The results are shown in Table-1.

Example-2 In Example-1, except that 3 g of methyl methacrylate was used instead of 3 g of styrene, and 7 g of azobisisobutyronitrile was used instead of 7 g of benzoyl peroxide.
Then, the treatment was carried out in the same manner as above to obtain a crosslinked copolymer. Table of results
It was noted in 2.

Comparative Example-2 A copolymer was obtained by the same treatment as in Example-2 except that the heat treatment in water in Example-2 was not carried out. The results are shown in Table-2.

Comparative Example-3 In Example-1, instead of 7 g of benzoyl peroxide,
A copolymer was obtained by the same procedure as in Example 1 except that 1 g of benzoyl peroxide was used. The results are shown in Table-1.

[Effect of the Invention] According to the present invention, a porous copolymer having a high specific surface area and a high pore volume can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-144393 (JP, A) JP-A-51-144394 (JP, A) JP-B-37-13792 (JP, B1)

Claims (3)

[Claims] 1. A crosslinked copolymer is obtained by suspension polymerization of a mixture of a porosifying agent comprising a monovinyl compound, a polyvinyl compound and an aromatic organic solvent in water in the presence of a polymerization initiator.
A method for producing a porous cross-linked copolymer, wherein the aromatic organic solvent is removed from the cross-linked copolymer, the method comprising suspension polymerization in the presence of 5 to 10% by weight of a polymerization initiator based on all monomers. The method for producing a porous crosslinked copolymer, wherein the crosslinked copolymer is heat-treated prior to the removal of the aromatic organic solvent. 2. The method for producing a porous crosslinked copolymer according to claim 1, wherein the heat treatment is carried out in water. 3. Suspension polymerization is 10 to 90% by weight of a polymerization initiator.
The method for producing a porous cross-linked copolymer according to claim 1 or 2, wherein is carried out under residual conditions at the end of the polymerization.