Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1994-04-20
2001-03-06
Henderson, Christopher (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06197893
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a dispersant having excellent properties of dispersing organic and inorganic substances and an effect of remarkably improving the stability of the dispersion system. In particular, the present invention relates to a dispersant for a coal/water slurry which dispersant exhibits excellent effects of increasing the concentration and improving stability of the slurry when it is left to stand.
It is known that polystyrenesulfonic acid produced by sulfonating polystyrene and salts thereof are usable as antistatic agents, dispersants and various other agents. They are used as, for example, antistatic agents for papers [Japanese Patent Publication for Opposition Purpose (hereinafter referred to as “J.P. KOKOKU” ) No. Sho 57-53953], antistatic agents for resins [Japanese Patent Unexamined Published Application (hereinafter referred to as “J.P. KOKAI”) No. Sho 59-8741], dispersants for coal/water slurry (J.P. KOKAI Nos. Sho 57-145187, Sho 62-590 and Sho 63-278997 and Japanese Patent Application No. Hei-1-338564), and dispersants for cements (J.P. KOKAI Nos. Sho 51-525, Sho 51-64527, Sho 56-41866, Sho 57-156355, Sho 60-46956 and Sho 63-25251). The polystyrenesulfonic acid and salts thereof are usually produced by polymerizing styrenesulfonic acid monomer or by sulfonating polystyrene. They have a structure shown the following general formula (II) or the like:
wherein l represents an integer and k represents 0 or an integer of at least 1. Although styrene of l recurring units in the above formula has one SO
3
X group, some of the recurring units may have 0 or two or more SO
3
X groups.
Although these known polymers exhibit an excellent effect for increasing the concentration of the dispersion system, their effect of improving the stability of the dispersion system is yet insufficient.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a new dispersant, in particular, capable of improving the stability of a dispersion system.
This and other objects of the invention will be apparent from the following description and Examples.
The inventors have found that the stability of the dispersion system can be improved by using a sulfonated polystyrene having a specified amount of indane ring at a terminal of the styrene recurring unit.
Namely, the present invention provides a dispersant comprising a polystyrenesulfonic acid having a weight-average molecular weight in the range of 2,000 to 100,000 or a salt thereof, wherein at least 70% of the terminals of the polymer chains have an indane ring of the formula (I):
wherein X represents a cation selected from the group consisting of a hydrogen, alkali metals, alkaline earth metals, ammonium and organic amines, and n and m each represent 0 or an integer of at least 1.
REFERENCES:
patent: 2446897 (1948-08-01), Young
patent: 4100336 (1978-07-01), Yax
patent: 4486574 (1984-12-01), Murray
Iihara Tadashi
Sugiyama Mituo
Yamada Jun-ichi
Burns Doane , Swecker, Mathis LLP
Henderson Christopher
Lion Corporation
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