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
2001-02-13
2003-10-07
Egwim, Kelechi (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, C524S555000
Reexamination Certificate
active
06630530
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the method and composition of a hydrophilic polymer dispersion containing a colloidal silica to be used for the retention aids of fine particles in papermaking system. More particularly, it relates to the method and composition of a hydrophilic polymer dispersion containing a colloidal silica, which can be used for recycling resources and reducing pollution of the waste water by retaining fine particles in papermaking system.
BACKGROUND ART
In the paper industry, the energy expense reaches 10~15% of cost. The large quantity of waste water occurs due to the use of much water in production. Especially, the accumulation of anionic trash in the system induces the declination of retention of fine particles. Therefore, in case that raw material including a lot of fillers contaminates the waste water, the cost for treatment may increase.
Not a few retention aids have been developed, but they have to be applied to the paper having high quality, and they occur much waste water. Further, more than two materials of retention aids have to be used, because more than two points have to be input respectively. Hence, it has a lot of drawbacks of: i ) difficulty of controlling process, ii) low stability of operation, and iii) production of the paper having low quality.
For example, there are many kinds of retention aids based upon various materials, such as, polyacrylamide, polyamine, polyamidoamine, polyethyleneimine and polyethyleneoxide. Among them, the polyacrylamide derivative used for retention aid or paper strength agent can be prepared by the polymerization reaction of dimethylamine, formaldehyde and homopolymer of acrylamide.
The efficiency of polyacrylamide is improved in addition to the particle, such as, bentonite and colloidal silica. Further, in the cationic polymer dispersion, the content of cationic monomer is preferably 10~20 mole % due to the low cationicity. Therefore, the flock having large size and low density is obtained by bridging flocculation, and the paper having low quality is obtained. The excess input of retention aids induces the reduction of fiber formation on the paper. In case that the anionic trash is accumulated in the system, the flocculation is reduced.
Allied Colloids Co., Ltd. provides the ‘Hydrocol’ system as a retaining method, which has to inject each cationic polymer and each bentonite respectively. Therefore, it has a lot of drawbacks of: i) limited range of application, ii) limited effect to specific paper due to its high cationicity, and iii) large selectivity of effect. Further, it can be used by following steps of: i) forming the flocculation by adding cationic polymer to pulp slurry, ii) destroying the flocculation by applying strong shear force, and ii) inducing the reflocculation by adding bentonite to said flocculation.
Akzo Nobel Co., Ltd. provides the ‘Compozil’ system using cationic starch and colloidal silica, and the ‘Compozil-P’ system using cationic polymer and colloidal silica. In case that the cationic starch in this product is flowed out of the system of ‘Compozil’, it has a lot of drawbacks of: i) increasing the pollution load of the waste water, and ii) increasing the cost for the retention. In the system of ‘Compozil-P’, a diameter of said colloidal silica has to be less than 10 nm, and the solid content of said colloidal silica has to be less than 10%. Hence, a large amount of transport cost is required. Further, the colloidal silica structured by linear branch of globular silica is unstable, and colloidal silica having less than 3% of solid content has to be provided.
Meanwhile, all developed retention aids can be classified into the following groups of: i) retention aid comprising poly-diallyldimethylammoniumchloride or copolymer of acrylamide and diallyldimethylammoniumchloride; ii) microparticle system comprising organic coagulant and cationic polyacrylamide; iii) microparticle system comprising organic coagulant and anionic polyacrylamide; iv) retention system comprising starch and cationic polymer; and v) retention aid comprising solubilized polymer. However, it has a lot of problems of: i) maintaining the retention of raw material, and ii) inducing the pollution. Further, the retention aid influences the quality of paper, for example, strength and degree of whiteness.
The aqueous dispersions of water-soluble nonionic and anionically charged vinyl and allyl addition polymers were disclosed in WO 97/34933. Also, they can be obtained by polymerizing in the presence of an anionically charged water-soluble polymer stabilizer in a saturated salt solution.
Further, the polymerization process of preparing a water-soluble polymer in the form of a water-continuous dispersion was described in European Pat. 0 630,909 A1. In this process, the peak in-production viscosity developed in the aqueous reaction mixture is lower than the peak in-production viscosity developed in an equivalent batch polymerization.
For forming dialkylaminoalkyl (meth)acrylamide polymer dispersions, a novel dispersant system was disclosed in U.S. Pat. No. 5,597,859. Further, European Pat. 0 839,767 A2 suggested a method for clarifying ink-laden water obtained from the recycling of paper stocks by treating said water with a conventional coagulant followed by treatment with a hydrophilic dispersion polymer. In this method, the hydrophilic dispersion flocculant is a copolymer of DMAEA.MCQ [dimethylaminoethyl (meth)acrylate methyl chloride quaternary] and (meth)acrylamide.
The improved process for the preparation of water soluble polymer dispersion was disclosed in European Pat. 0 657,478 A2.
However, none of prior references discloses the far enhanced retention property of fine particles compared to formerly developed hydrophilic polymer dispersion
DISCLOSURE OF INVENTION
The present invention relates to a hydrophilic polymer dispersion composition containing a colloidal silica and a method for preparing such composition which comprises the following steps of: i) mixing acrylamide, cationic monomer, anionic monomer, polymer of cationic monomer, anionic salt and colloidal silica, ii) 1st-polymerizing the mixture obtained in previous step, iii) 2nd-polymerizing the 1st-polymerized mixture containing unreacted monomers completely, and iv) adding and mixing anionic salt to obtained polymers.
Further, the hydrophilic polymer dispersion containing a colloidal silica of the present invention is prepared by following steps of:
i) mixing 1.0~25 wt % of acrylamide, 0~2 wt % of anionic monomer selected from the group consisting of acrylic acid, methacrylic acid and itaconic acid, 1.0~30 wt % of cationic monomer mixture of compound of formula I and formula II, 0.5~5 wt % of polymer selected from the group consisting of homopolymer of compound of formula I, homopolymer of compound of formula II and copolymer of compound of formula I and formula II, 10~30 wt % of anionic salt, 0.5~10 wt % of colloidal silica, 0.01~1 wt % of nonionic surfactant, 0.05~2 wt % of dispersion stabilizer and 40~75 wt % of water
ii) 1st-polymerizing the mixture in addition to 0.001~0.1 wt % of polymerization initiator to said mixture;
iii) 2nd-polymerizing the 1st-polymerized mixture containing unreacted monomers completely; and
iv) adding and mixing 10~30 wt % of anionic salt to obtained polymers.
wherein
R
1
is hydrogen atom or methyl;
R
2
and R
3
are each independently alkyl group having 1 to 3 carbon atoms;
A
1
is oxygen atom or NH;
B
1
is alkylene group having 2 to 4 carbon atoms or hydropropylene; and
X
1
is anionic counter ion.
wherein
R
4
is hydrogen atom or methyl;
R
5
and R
6
are each independently alkyl group having 1 to 2 carbon atoms;
R
7
is hydrogen atom or alkyl group having 1 to 2 carbon atoms;
A
2
is oxygen atom or NH;
B
2
is alkylene group having 2 to 4 carbon atoms or hydropropylene; and
X
2
is anionic counter ion.
BEST MODE FOR CARRYING OUT THE INVENTION
The conventional retention aid contains anionic polymer, acrylamide or nonionic polymer, such as, starch, whereas the retention aid of the presen
Birch & Stewart Kolasch & Birch, LLP
Egwim Kelechi
Green Technology Inc.
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