Pigment dispersing resins

Details Pigment dispersing resins Pigment dispersing resins

2002-08-20

2004-06-01

Zalukaeva, Tatyana (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...

C524S556000, C523S400000, C523S402000, C523S436000, C428S413000, C428S523000

Reexamination Certificate

active

06743848

ABSTRACT:

This invention relates to novel pigment dispersing resins excelling in pigment dispersing ability, pigment color developing ability and let down stability; to pigment dispersions formed by using the resins; and to paint compositions containing the pigment dispersions.
For paints, inks and the like in general, organic or inorganic pigments are widely used, for such purposes as coloring, shading, pleasant appearance and rust-proofing. Where these pigments are used in paints or inks, it occasionally occurs that dispersion stability of the pigments is insufficient, which leads to poor fluidability, shift in color phase or insufficient gloss of coatings formed of such paints. Heretofore numbers of proposals have been made to solve those problems.
For example, Japanese Patent Application Laid-Open Nos. 96175/1984, 36252/1990 and 81849/1998 proposed addition of pigment derivatives having identical skeletal structures with those of pigments, at the time of dispersing said pigments, or use of pigments which were treated with such pigment derivatives in advance. Processes according to such proposals, however, invariably show still insufficient pigment dispersing effect, and are subject to such defects as inferior in applicability for wide use because many kinds of pigment derivatives are necessary and also high production costs.
On the other hand, varieties of pigment dispersing agents are commercially available, such as acrylic resin type, polyester resin type, urethane resin type, polyester-modified urethane resin type and the like and they are finding wide use. Those commercially sold pigment dispersing agents, however, are subject to the problem that they cause deterioration in performance of coatings such as weatherability and other physical properties. In particular, when they are blended in paints in large quantities, deterioration in the coating performance becomes notable, and thus they are not fully satisfactory.
Moreover, automotive paint industries are facing in these recent years demands for high quality coating appearance achievable with high sharpness, transparency, high color-developing property and the like, of the levels which cannot be satisfied by presently available pigment dispersing resins or assistants in general, besides the conventional demands for the coating performances in respect of weatherability and other physical properties. It is also expected that increasingly wider varieties of coating colores will be required in the future, and hence development of corresponding pigment dispersing resins having the dispersing ability of those versatile coloring materials is required.
Still in addition, decrease in organic solvent content of paints to provide high solid content paints is an urgent responsibility of paint industries, for preservation of terrestrial environments. As means for providing higher solid content paints, studies have been made generally in the direction of decreasing molecular weights of resins for paint to reduce viscosity of paint preparations. Decrease in molecular weight of the resins, however, is apt to invite deterioration of curability or degradation in coating performances.
Also as a means for providing high solid content paint, increase in pigment concentration in paint (reduction in resin quantity to be used for dispersing a same amount of pigment) can be named, besides lowering molecular weight of resins for paint. Generally, however, attempts to achieve higher pigment concentration in paint are liable to invite increase in viscosity of pigment dispersions, mutual aggregation of pigments in pigment dispersions or paints, and furthermore aggravation in let down stability in occasions of formulating paints, rendering it difficult to obtain stable pigment dispersions or paints.
With the view to solve those problems, we have engaged in concentrative studies and now discovered that use of resins having specific functional groups, which resins are obtained through copolymerization reaction of a specific macromonomer with other copolymerizable unsaturated monomer or monomers, enables to provide pigment dispersions exhibiting markedly improved pigment dispersing ability, color developing property of pigment and let down stability also under high pigment concentration condition; and that paint compositions in which said pigment dispersions are used form coatings of superb finished appearance, weatherability and physical properties. This invention is whereupon completed.
Thus, the present invention provides a pigment dispersing resin (“pigment dispersing resin I”) having a weight-average molecular weight within a range of 1,000-150,000, which is obtained by copolymerizing a monomeric mixture comprising
(a) a macromonomer obtained by polymerizing at least one ethylenically unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent, or an addition cleavage-type chain transfer agent and if necessary a radical polymerization initiator, which macromonomer having a resin acid value less than 50 mgKOH/g, and
(b) at least one copolymerizable unsaturated monomer,
wherein at least one monomer among the ethylenically unsaturated monomer(s) constituting said macromonomer (a) and the copolymerizable unsaturated monomer(s) (b) has a functional group selected from substituted or unsubstituted amino group, quaternary ammonium salt group, sulfonic group, phosphoric group and carboxyl group.
The invention also provides a pigment dispersing resin (“pigment dispersing resin II”) having a weight-average molecular weight within a range of 1,000-150,000, which is obtained by copolymerizing a monomeric mixture comprising
(a) a macromonomer obtained by polymerizing at least one ethylenically unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent, or an addition cleavage-type chain transfer agent and if necessary a radical polymerization initiator, which macromonomer having a resin acid value less than 50 mgKOH/g, and
(b) at least one copolymerizable unsaturated monomer,
wherein at least one monomer among the ethylenically unsaturated monomer(s) constituting said macromonomer (a) and the copolymerizable unsaturated monomer(s) (b) has a group which is convertible to a functional group selected from substituted or unsubstituted amino group, quaternary ammonium salt group, sulfonic group, phosphoric group and carboxyl group,
and then converting said convertible groups in the formed resin to corresponding functional groups.
The invention furthermore provides a pigment dispersing resin (“pigment dispersing resin III”) containing long chain alkyl groups, which is obtained by introducing long chain alkyl groups into above pigment dispersing resin I or II.
The invention also provides a pigment dispersing resin (“pigment dispersing resin IV”) having a weight-average molecular weight within a range of 1,000-150,000, which is obtained by copolymerizing a monomeric mixture comprising.
(c) a long chain alkyl group-containing macromonomer having a resin acid value less than 50 mgKOH/g, which is obtained by either subjecting a carboxyl-containing macromonomer and an epoxy-containing long chain alkyl compound to an esterification reaction, said carboxyl-containing macromonomer being obtained by copolymerizing a monomeric mixture comprising a carboxyl-containing unsaturated monomer and at least one other ethylenically unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent, or an addition cleavage-type chain transfer agent and if necessary a radical polymerization initiator; or by causing an epoxy-containing long chain alkyl compound to be concurrently present in said copolymerization reaction system to effect the copolymerization reaction and the esterification reaction at the same time, and
(b) at least one copolymerizable unsaturated monomer, wherein at least one monomer among said macromonomer (c) and copolymerizable unsaturated monomer(s) (b) has a functional group selected from substituted or unsubstituted amino group, quaternary ammonium salt group, sulfonic group, phosphoric

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