Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-07-06
2001-02-13
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S458000, C524S460000, C526S074000, C526S201000, C526S303100
Reexamination Certificate
active
06187853
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing a dispersion of a water-soluble polymer having low viscosity and high fluidity, dispersed in an aqueous salt solution as dispersionmedium, and widely used in, for example, a flocculant and a dewatering agent used as a water treatment agent, paper production chemicals used in a papermaking process, a dispersion stabilizer of various types of suspensions or a soil improver, and more particularly, to a process for producing a water-soluble polymer dispersion characterized by adding a specific chemical substance to maintain the viscosity of the reaction solution at a low level during polymerization.
BACKGROUND ART
As an example of a process for producing a dispersion of fine water-soluble polymer particles in an aqueous salt solution as dispersion medium having low viscosity and high fluidity in the prior art, processes comprising polymerizing while stirring in the presence of a dispersant such as polymer electrolyte are disclosed in European Patent Publication No. 0183466 and European Patent Publication No. 0364175.
In the case of carrying out the processes disclosed in the patent publications described above, the phenomenon occurs in which the viscosity of the reaction solution increases significantly during polymerization. Consequently, a large load is applied to the agitator, thereby creating the need to use a high-powered motor and stirring blades that are able to withstand high levels of torque. This results in the problem of high cost of the reaction apparatus. In addition, since the viscosity of the reaction solution becomes high, there are portions that are not mixed properly, thereby resulting in the additional problem of the formation of coarse particles.
DISCLOSURE OF THE INVENTION
As a result of conducting various studies on a process that solves the above-mentioned problems, the inventors of the present invention found that by adding a specific chemical substance to the reaction solution, the increase in viscosity of the reaction solution during polymerization can be suppressed, thereby leading to completion of the present invention.
Namely, in a process for producing a water-soluble polymer dispersion comprising polymerizing water-soluble monomers having double bonds in an aqueous salt solution that dissolves the monomers but does not dissolve the formed polymer while stirring in the presence of a dispersant composed of a polymer electrolyte soluble in this aqueous salt solution to obtain fine polymer particles dispersed in the aqueous salt solution, the present invention suppresses the phenomenon of the significant increase in viscosity of the reaction solution during polymerization by adding at least one viscosity-increase suppressor selected from the group consisting of:
(A) a polyvalent carboxylic acid or a salt thereof,
(B) a polyvalent phenol,
(C) a cyclic compound containing a hydroxyl group and a carboxyl group or a salt thereof,
(D) gluconic acid or a salt thereof,
(E) a reaction product obtained by reacting methoxyhydroquinone and/or (meth)acrylic cationic monomer with a compound that generates radicals in an oxidizing atmosphere,
(F) a reaction product obtained by reacting (meth)acrylic cationic polymer with a compound that generates radicals in an oxidizing atmosphere,
(G) a reaction product obtained by reacting (meth)acrylic cationic polymer with an oxidant, and a mixture thereof, thereby making it possible to carry out production even with a low-powered agitator, while also reducing the formation of coarse particles.
In the present invention, it is preferable that the water-soluble monomers having double bonds be composed of 0-30 mol % acrylic acid, 0-100 mol % acrylamide and 0-100 mol % cationic monomer represented by the following formula 1 and/or the following formula 2:
(wherein, A represents O or NH, B represents C
2
H
4
, C
3
H
6
or C
3
H
5
OH, R
1
represents H or CH
3
, R
2
and R
3
represent an alkyl group having 1-4 carbon atoms, R
4
represents hydrogen, an alkyl group having 1-4 carbon atoms or benzyl group, and X
−
represents a counter ion);
(wherein, A represents O or NH, B represents C
2
H
4
, C
3
H
6
or C
3
H
5
OH, R
5
, R
6
, R
7
and R
8
represent H or CH
3
, and X
−
represents a counter ion)
In the present invention, it is preferable that said dispersant be a cationic polymer electrolyte in which 50-100 mol % of at least one type of cationic monomer selected from the group consisting of dimethylaminoethyl(meth)acrylate salt, dimethylaminopropyl(meth)acrylamide salt, di(meth)allylamine salt, (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acrylamidopropyltrimethylammonium chloride, dimethyldiallylammonium chloride and a mixture thereof, and 50-0 mol % acrylamide are polymerized.
In the present invention, it is preferable that a salt that forms the aqueous salt solution be a bivalent anionic salt.
At this time, it is preferable that the (A) polyvalent carboxylic acid or the salt thereof be oxalic acid, adipic acid, tartaric acid, malic acid, phthalic acid and salts thereof.
Further, it is preferable that the (B) polyvalent phenol be resorcinol or pyrogallol.
In addition, it is preferable that the (C) cyclic compound having a hydroxyl group and a carboxyl group be m-hydroxybenzoic acid, p-hydroxybenzoic acid, salicylic acid, gallic acid, tannic acid and a salt thereof.
In addition, the viscosity-increase suppressor (E) can be obtained by reacting a compound that generates radicals in an oxidizing atmosphere in a solution containing methoxyhydroquinone and/or (meth)acrylic cationic monomer.
Furthermore, the viscosity-increase suppressor (F) can be obtained by reacting a compound that generates radicals in an oxidizing atmosphere with (meth)acrylic cationic polymer.
The viscosity-increase suppressor (G) can be obtained by reacting an oxidant with (meth)acrylic cationic polymer.
It is preferable that the total added amount of the viscosity-increase suppressors listed in (A) through (G) above be from 10 ppm to 10,000 ppm based on the weight of the reaction mixture.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be explained in detail below.
The present invention is a process for producing a water-soluble polymer dispersion comprising polymerizing water-soluble monomers having double bonds in an aqueous salt solution that dissolves the monomers but does not dissolve the formed polymer while stirring in the presence of a dispersant composed of a polymer electrolyte soluble in this aqueous salt solution to obtain fine polymer particles dispersed in the aqueous salt solution, characterized by adding at least one viscosity-increase suppressor selected from the group consisting of:
(A) a polyvalent carboxylic acid or a salt thereof,
(B) a polyvalent phenol,
(C) a cyclic compound containing a hydroxyl group and a carboxyl group or a salt thereof,
(D) gluconic acid or a salt thereof,
(E) a reaction product obtained by reacting methoxyhydroquinone and/or (meth)acrylic cationic monomer with a compound that generates radicals in an oxidizing atmosphere,
(F) a reaction product obtained by reacting (meth)acrylic catinic polymer with a compound that generates radicals in an oxidizing atmosphere,
(G) a reaction product obtained by reacting (meth)acrylic cationic polymer with an oxidant, and a mixture thereof.
The water-soluble monomer having double bonds used in the present invention is suitably selected from cationic monomers such as an amine salt of dialkylaminoalkyl (meth) acrylate and quaternary compounds thereof, an amine salt of dialkylaminoalkyl(meth)acrylamide and quaternary compounds thereof, an amine salt of dialkylaminopropyl (meth) acrylamide and quaternary compounds thereof, an amine salt of dialkylaminohydroxypropyl(meth)acrylamide and quaternary compounds thereof and diallylamines salt and quaternary compounds thereof; nonionic monomers such as (meth)acrylamide, N-vinylcarboxylic acid amide, acrylonitrile and vinyl acetate; anionic monomers such as (meth)acrylic acid, acrylamide-2-methylpropane sulfonic acid and itaconi
Ohara Takumi
Sakai Kenji
Suzuki Mika
Takeda Hisao
Egwim Kelechi C.
Hymo Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Wu David W.
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