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
2001-08-01
2003-04-01
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S223000, C524S502000, C526S310000
Reexamination Certificate
active
06541571
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed to polymeric dispersant resins that are useful in the manufacture of resin-containing pigment dispersions and surface coating compositions, and to pigment dispersions and surface-coating compositions that contain these dispersants. It further relates to polymer dispersant resins that are compatible with a wide variety of resin systems and film-forming polymers. This invention also relates to the use of this dispersant resin in compatibilizing at least two polymers, wherein at least two polymers are incompatible. This invention also relates to polymer blends that are compatibilized using the dispersant resin of this invention. Due to the novel composition and molecular weight of the polymeric dispersants, they are especially suited for use in high solids compositions.
BACKGROUND OF THE INVENTION
To be useful as a multipurpose dispersant with wide compatibility in pigment and coating dispersions, the dispersant should be compatible with the acrylic, polyester, alkyd, epoxy resin, polyurethane, and other film-forming resins that are commonly used in surface coating compositions. It should also be able to disperse both organic and inorganic pigments. It should also enhance the tint strength of the pigments, improve gloss, hiding power, and stability of the surface coating composition.
Polymeric dispersants have been known in the art. During coating manufacture, it has been typical to disperse the pigments into only a portion of the total resin vehicle of which the coating composition is comprised, together with appropriate liquid carriers and additives. The resulting dispersion is then mixed with the remainder of the total resin vehicle used in the coating composition. These additions can take place by the ultimate user of the coating composition to adjust color, or they may be used during the actual manufacture of the coating composition itself. However, most pigment dispersions are very specific in their performance and are compatible with only a small number of the diverse solvents and film-forming resins used in coating compositions. A number of polymeric dispersants have been proposed for as multipurpose widely compatible pigment dispersions, but none has proven to be entirely satisfactory. Some do not have the required compatibility with a wide range of the film-forming resins and solvents, or do not have good pigment-wetting characteristics, while others adversely affect the properties of the surface-coating compositions or increase their cost appreciably.
It has now been found that polymeric dispersant resins made from polymerization products of specific monomer units are capable of acting as multipurpose dispersants because they are compatible with a wide range of film-forming resins, as well as capable of dispersing both organic and inorganic pigments. Due to its solvating properties, use of this polymeric dispersant resin reduces the need for solvents typically used for pigment dispersions. Dispersants of this invention can disperse both organic and inorganic pigments wherein the film-forming resin is an acrylic, alkyd, polyester, epoxy resin, polyurethane, or non-aqueous dispersion resin. The dispersants of this invention can also act as a compatibilizer to aid in blending some mutually incompatible polymers (that is, those polymer systems being relatively immiscible and creating a cloudy appearance upon mixing). The dispersants of this invention are useful in pigment dispersions, inks, and surface-coating resin-containing compositions.
BRIEF SUMMARY OF THE INVENTION
An aspect of this invention is a polymeric dispersant, said dispersant being the polymerization reaction product of a mixture of monomers consisting essentially of:
(a) from about 10% to about 40% by weight styrene; and
(b) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having 1 to 8 carbon atoms in the alkyl group; and
(c) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having greater than 8 carbon atoms in the alkyl group; and
(d) from about 5% to about 25% by weight of at least one alkyl acrylate monomer having from 1 to 18 carbon atoms in the alkyl group; and
(e) from about 7% to about 25% by weight of at least one hydroxy-functional ethylenically unsaturated monomer having a molecular weight of less than 2000; and
(f) from about 0.1% to about 15% of a compound providing an amine functional moiety, said compound being an acrylate or methacrylate compound containing amino groups, copolymerizable with (a), (b), (c), (d), and (e); wherein the dispersant is substantially free of acid functionality.
The dispersant of this invention is especially adapted for dispersing pigments therein and being compatible with a variety of alkyd resins, acrylic resins, non-aqueous dispersions, inks, and film-forming polymers.
In another aspect, this invention is a polymeric dispersant that is particularly useful due to its composition and pigment dispersions prepared therefrom. The polymeric dispersants of this invention provide excellent pigment wetting characteristics and stable dispersions. The polymeric dispersants also provide low viscosity dispersions suitable for use in high solids applications. The dispersions of this invention provide higher hiding power (opacity) and tinting strength with pigments, and the dispersions of this invention eliminate or minimize the need for surfactants used in dispersing pigments.
In yet another aspect, this invention is a high solids surface-coating composition comprising the polymeric dispersant resin. The surface coating compositions comprise the polymeric dispersant and other film-forming polymers, optionally in combination with a crosslinker. The surface coating composition may also include a pigment component.
In still yet another aspect, this invention is a process for compatibilizing at least two polymers, wherein at least two polymers are mutually incompatible, said process comprises:
(i) adding to at least one of the polymers an effective amount of a compatibilizing dispersant, wherein said dispersant is the polymerization reaction product of a mixture of monomers consisting essentially of:
(a) from about 10% to about 40% by weight styrene; and
(b) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having 1 to 8 carbon atoms in the alkyl group; and
(c) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having greater than 8 carbon atoms in the alkyl group; and
(d) from about 5% to about 25% by weight of at least one alkyl acrylate monomer having from 1 to 18 carbon atoms in the alkyl group; and
(e) from about 7% to about 25% by weight of at least one hydroxy-functional ethylenically unsaturated monomer having a molecular weight of less than 2000; and
(f) from about 0.1% to about 15% of a compound providing an amine functional moiety, said compound being an acrylate or methacrylate compound containing amino groups, copolymerizable with (a), (b), (c) and (d) and (e); wherein the dispersant is substantially free of acid functionality; and
(ii) combining additional polymers to the polymer in step (1); and
(iii) blending all polymers until properly compatibilized.
In yet still another aspect, this invention is a compatibilized polymer blend, comprising:
(i) at least two mutually incompatible polymers; and
(ii) a compatibilizing dispersant being the polymerization reaction product of a mixture of monomers consisting essentially of:
(a) from about 10% to about 40% by weight styrene; and
(b) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having 1 to 8 carbon atoms in the alkyl group; and
(c) from about 10% to about 55% by weight of at least one alkyl methacrylate monomer having greater than 8 carbon atoms in the alkyl group; and
(d) from about 5% to about 25% by weight of at least one alkyl acrylate monomer having from 1 to 18 carbon atoms in the alkyl group; and
(e) from about 7% to about 25% by weight of at least one hydroxy-functional ethylenically unsaturated monomer hav
Katterle Paul R.
McDonald Robert E.
The Sherwin-Williams Company
Tsang Vivian Y.
Yoon Tae H.
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