Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-10-04
2002-03-26
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S150000, C521S056000, C521S060000, C095S088000
Reexamination Certificate
active
06362245
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a porous copolymer particle containing a structural unit derived from an N-vinylcarboxylic acid amide and another monomer, and also relates to a preparation process thereof, and also use thereof.
BACKGROUND OF THE INVENTION
An N-vinylcarboxylic acid amide (hereinafter sometimes referred to as “monomer (A)”) has high hydrophilicity, therefore, use of a copolymer of the N-vinylcarboxylic acid amide and another monomer copolymerizable therewith (hereinafter sometimes referred to as “monomer (B)”) as a hydrophilic gel has been proposed (see, for example, JP-A-4-323213 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)). By increasing the ratio of the monomer (A), the hydrophilicity is elevated. The hydrophilic gel allowed to hold a large amount of water is used as a thickener, a dispersion stabilizer, a lubricant or the like. However, use as a porous particle, for example, as a packing material for chromatography, is not described.
With respect to the production process of the above-described copolymer particle, a reversed phase emulsion polymerization method is disclosed, for example, in JP-A-63-90513. However, polymer particles obtained by this method are dispersed in a cracking solvent, the dispersion in the hydrated state is dissolved as it is in water in the presence of a surface active agent for inversion, and the aqueous solution obtained is used as a coagulating agent, for recovery of petroleum or the like. Thus, this is not suitable for use as a polymer particle.
JP-A-61-141712 discloses a method for obtaining a particulate polymer by dispersing an aqueous monomer solution in a hydrocarbon-type dispersion medium using an oil-soluble polymer dispersion stabilizer such as ethyl cellulose and subjecting the monomer to reversed phase suspension polymerization. However, in this method, the object is also to obtain a water-soluble polymer and use of the polymer in the particulate state is not described. Moreover, this method has a problem in the treatment of the hydrocarbon dispersion medium generated in a large amount after the polymerization.
JP-A-6-122725 discloses a dispersion polymerization method of polymerizing a monomer in a solvent which dissolves the monomer but does not dissolve the copolymer produced, in the presence of a polymer dispersant. The polymer produced by this method is not porous and the polymer particle obtained has a small particle size of around 1 &mgr;m, therefore, the polymer particle cannot be used for general purposes.
SUMMARY OF THE INVENTION
An object of the present invention is to obtain a porous copolymer particle having both hydrophilic properties and hydrophobic properties, thereby exhibiting composite performance, being porous, and having excellent mechanical strength. The particle is suitable for use in the particulate state and usable for general purposes. An object also is to provide an absorbent or packing material comprising the porous copolymer particle. A packing material may be used for solid phase extraction and chromatography. An object also is to provide an efficient preparation process thereof.
The present invention provides a porous copolymer particle, a preparation process thereof and a use thereof described below:
(1) A porous copolymer particle comprising a particle of a copolymer comprising (i) from 5 to 60 wt % of a structural unit derived from a monomer (A) selected from N-vinylcarboxylic acid amide represented by formula (I):
wherein R
1
represents a hydrogen atom or a methyl group, and R
2
represents a hydrogen atom, a C
1
-C
8
alkyl group, a phenyl group or a phenyl group substituted with a methyl group or an ethyl group, (ii) from 40 to 95 wt % of a structural unit derived from a copolymerizable monomer (B) which contains a crosslinking monomer, or a particle of a modified product of the copolymer, and the particle having a particle size of from 0.1 to 2,000 &mgr;m.
(2) The porous copolymer particle as described in (1) above, wherein the copolymer comprises (i) from 5 to 60 wt % of the structural unit derived from the monomer (A) and (ii) from 40 to 95 wt % of the structural unit derived from the monomer (B).
(3) The porous copolymer particle as described in (1) or (2) above, wherein R
2
in formula (I) represents a hydrogen atom, a methyl group or an ethyl group.
(4) The porous copolymer particle as described in (1) or (2) above, wherein the monomer (A) is N-vinylacetamide.
(5) The porous copolymer particle as described in any one of (1) to (4) above, wherein the particle size is from 1 to 500 &mgr;m.
(6) The porous copolymer particle as described in (1) or (2) above, wherein the copolymer particle has a permanent pore having a pore size of from 2 to 800 nm.
(7) The porous copolymer particle as described in (3) above, wherein the copolymer particle has a permanent pore having a pore size of from 2 to 800 nm.
(8) The porous copolymer particle as described in (4) above, wherein the copolymer particle has a permanent pore having a pore size of from 2 to 800 nm.
(9) The porous copolymer particle as described in any one of (1) to (8) above, wherein the copolymer particle has a permanent pore having a pore size of from 2 to 100 nm.
(10) The porous copolymer particle as described in any one of (1) to (9) above, wherein 50 wt % or more of the monomer (B) is a crosslinking monomer.
(11) A process for producing a porous copolymer particle comprising
dissolving a monomer containing (i) from 5 to 60 wt % of a structural unit derived from a monomer (A) selected from N-vinylcarboxylic acid amide represented by formula (I):
wherein R
1
represents a hydrogen atom or a methyl group, and R
2
represents a hydrogen atom, a C
1
-C
8
alkyl group, a phenyl group or a phenyl group substituted with a methyl group or an ethyl group and (ii) from 40 to 95 wt % of a structural unit derived from a copolymerizable monomer (B) which contains a crosslinking monomer, in a diluent in which these monomers are soluble but in which the polymer produced is not soluble;
suspending the resulting monomer solution in an aqueous medium containing a dispersion stabilizer;
polymerizing the monomers in the presence of a polymerization initiator; and
if desired, modifying the copolymer obtained.
(12) The process as described in (11) above, wherein R
2
in formula (I) represents a hydrogen atom, a methyl group or an ethyl group.
(13) The process as described in (11) above, wherein the monomer (A) is N-vinylacetamide.
(14) The process as described in (11) above, wherein 50 wt % or more of the monomer (B) is a crosslinking monomer.
(15) The process as described in (12) above, wherein 50 wt % or more of the monomer (B) is a crosslinking monomer.
(16) The process as described in (13) above, wherein 50 wt % or more of the monomer (B) is a crosslinking monomer.
(17) The process as described in any one of (11) to (14) above, wherein the aqueous medium contains a salt.
(18) The process as described in (15) above, wherein the aqueous medium contains a salt.
(19) The process as described in (16) above, wherein the aqueous medium contains a salt.
(20) An absorbent comprising a porous copolymer particle comprising a particle of a copolymer comprising (i) from 5 to 60 wt % of a structural unit derived from a monomer (A) selected from N-vinylcarboxylic acid amide represented by formula (I):
wherein R
1
represents a hydrogen atom or a methyl group, and R
2
represents a hydrogen atom, a C
1
-C
8
alkyl group, a phenyl group or a phenyl group substituted with a methyl group or an ethyl group, (ii) from 40 to 95 wt % of a structural unit derived from a copolymerizable monomer (B) which contains a crosslinking monomer, or a particle of a modified product of the copolymer, and the particle having a particle size of from 0.1 to 2,000 &mgr;m.
(21) The absorbent as described in (20) above, wherein R
2
in formula (I) represents a hydrogen atom, a methyl group or an ethyl group.
(22) The absorbent as described in (20) above, wherein the monomer (A) is N-vinylacetamide.
(23) A pack
Shimbo Kuniaki
Suzuki Hiroshi
Takahashi Ryuji
Bagwell-Bissett Melanie
Seidleck James J.
Showa Denko Kabushiki Kaisha
Sughrue & Mion, PLLC
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