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
1999-02-23
2002-03-26
Niland, Patrick D. (Department: 1714)
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...
C524S401000, C524S430000, C524S439000, C524S441000, C524S504000, C525S077000, C525S078000, C525S079000, C525S080000, C525S279000, C525S286000, C525S293000, C525S296000, C525S309000
Reexamination Certificate
active
06362274
ABSTRACT:
The invention relates to grafted copolymers comprising at least three sequences of distinct chemical nature, among which one or more sequence(s) for anchoring on solid particles, one or more sequence(s) of hydrophobic character and one or more sequence(s) of hydrophilic character.
The invention also concerns their process of preparation, the compositions containing them, their use as dispersing agent, stabilizer of solid particles and/or emulsifier in an aqueous and/or organic medium, as well as their use for the preparation of pigmentary dispersions in an aqueous and/or organic medium.
At the end of their process of manufacture, the solid particles used in the ink and paint industry, essentially pigments and fillers, are in the form of aggregates or agglomerates. Their incorporation in a liquid in order to obtain a stable suspension therefore necessitates a prior step of dispersion, step during which these assemblies are dissociated into elementary particles under the effect of considerable mechanical stresses.
However, the action of these mechanical forces could not be efficient in the absence of a dispersing agent.
These copolymers, employed in solution by adsorption on the surface of the solid, or by coating of the particle before incorporation thereof in the liquid, intervene at each step of the dispersion.
Firstly, they ensure a good wetting of the particle by the continuous phase, by replacing the film of air surrounding the surface of the solid by molecules of liquid. They then substantially improve the output of the dissolvent/grinder during the phase of disagglomeration of the associates. Finally, these dispersion agents, adsorbed on the surface of the solid, constitute a layer of solvated polymer, at the origin of steric forces of repulsion, and, in the case of polyelectrolytes in aqueous medium, of electrostatic forces of repulsion, which oppose the attractive Van de Waals forces, thus ensuring the stability of the dispersion.
In order to be efficient, a copolymer which may be used as a dispersant must therefore comprise a sequence of anchoring, presenting a good affinity for the surface of the particles, as well as one or more sequence(s) compatible with the continuous phase in which these solids are incorporated.
In the absence of one of these constituents, or in the case of desorption of the dispersant, the system flocculates, a phenomenon which shows itself by the reagglomeration of the particles, and an increase in viscosity of the dispersion. In the particular case of a paint, a poor dispersion of the pigments within the binding agent is translated by considerable colorimetric divergences and loss of brillance on the final film.
In order to overcome these problems, dispersion agents have been proposed, which make it possible to formulate paints specifically in aqueous medium (EP 018 099) or in organic medium (U.S. Pat. No. 4 032 698; GB 1 393 401 and 1 393 402). However, these products offer only a partial solution, insofar as the mixture of different pigments, inorganic and organic, or interactions between the dispersant and the continuous phase, as may be the case in lacquers, bring about a loss of stability of the suspension.
The synthesis of new additives, containing several sequences, based on the use of polyisocyanates, as described in Patents U.S. Pat. No. 4,647,647 or EP 0 520 586, makes it possible to overcome these difficulties. Nonetheless, the use of polyisocyanates, molecules presenting a high toxicity and poorly defined functionality, leads to obtaining a product constituted by a mixture of various structures, of which the properties of adsorption and of dispersion are not optimal. In addition, this process prevents the presence in the copolymer of polar functions containing a reactive hydrogen atom, chemical functions appreciated when using in an aqueous medium or for promoting the compatibility with the resins.
Furthermore, monografted copolymers, obtained by the “macromonomer” technique and/or grafting of telomers of polyether type on a preformed chain constituted by one or more unsaturated ethylene monomers and comprising nitrogenous moeities, form the subject matter of Patent EP 0 311 157.
The copolymers of the present invention contain a sequence allowing them to be anchored on the solid particles, particularly pigments and fillers, as well as at least 2 sequences of respectively hydrophilic and hydrophobic character, allowing use thereof in the compositions in aqueous and/or organic medium. The presence of a sequence insoluble in selective medium surprisingly increases the quantity of dispersant adsorbed on the surface of the particles, thus avoiding the phenomenon of flocculation during the mixture of different pigments.
On the other hand, the plurality of chemical functions within the same copolymer, as well as the possibility of formulating pigmentary concentrates without elongation resin, improve compatibility with the resins, thus allowing the formulation of paints from a wide range of binding agents.
Moreover, the process of synthesis makes it possible to obtain products of homogeneous structure, whose performances are not limited by the presence of contaminants.
The invention therefore has for its object a grafted copolymer comprising at least three sequences of distinct chemical nature, among which one or more sequence(s) for anchoring on the solid particles, one or more sequence(s) of hydrophobic character and one or more sequence(s) of hydrophilic character, constituted by:
1) 1 to 80% by mass, preferably 5 to 40% by mass, of one or more sequence(s) for anchoring on the solid particles, constituted by a straight or branched hydrocarbon chain, cycloalkyl or aromatic, comprising basic nitrogenous groups of type: heterocyclic, —NH
2
, —NH, —NHR, —NR
2
, —CONH
2
, —CONHR, —CONR
2
(where R is an alkyl radical (C
1
-C
6
) optionally substituted by one or more groups —OH, —COO—, —CO—, —O—, —SO
3
H), which may comprise —COO— groups, and whose molar mass is included between 150 and 10000, preferably between 300 and 3000, the mass content of basic nitrogenous monomers in the anchoring chain being 5% minimum and preferably 30%, and
2) 10 to 90% by mass, preferably 25 to 80% by mass, of one or more sequence(s) of hydrophobic character, constituted by a straight or branched hydrocarbon chain, cycloalkyl or aromatic, which may comprise groups —COO—, —S—, —F, —Si(OR′)
n
(R″)
2-n
— (where R′ and R″ represent similar or different alkyl or aryl radicals (C
1
-C
10
) and n=0 to 2), formed by monomer units whose parameter of solubility is less than or equal to 21.5 J
½
/cm
{fraction (3/2)}
, preferably less than 19 J
½
/cm
{fraction (3/2)}
, and whose molar mass is included between 250 and 10000, preferably between 500 and 3500, and
3) 10 to 90% by mass, preferably 15 to 70% by mass, of one or more sequence(s) of hydrophilic character, constituted by a straight or branched hydrocarbon chain comprising groups —O—, —OH, —NCO—, —COO—, —COOH, —CONH
2
, —CONHR′″ (where R′″ is an alkyl radical (C
1
-C
3
)), —NH—, —S—, —SO
3
H, formed by monomer units whose parameter of solubility is greater than 22 J
½
/cm
{fraction (3/2)}
, preferably greater than 22.5 J
½
cm
{fraction (3/2)}
, and whose molar mass is included between 250 and 10000, preferably between 300 and 3000.
It will be noted that there advantageously exist three different ways of combining the three types of sequences: anchoring, hydrophobic and hydrophilic. The grafted copolymers according to the invention may therefore present the following structures alternately:
principal anchoring chain+at least 2 respectively hydrophilic and hydrophobic grafts
principal hydrophobic chain+at least 2 respectively hydrophilic and anchoring grafts
principal hydrophilic chain+at least 2 respectively hydrophobic and anchoring grafts.
The grafted copolymers comprising a principal anchoring chain and at least 2 respectively hydrophilic and hydrophobic grafts are preferred compounds according to the invention.
Accordi
Lefevre Daniel
Legrand Pierre
Lerch Jean-Phillipe
Riess Gerard
Les Peintures Jefco
Niland Patrick D.
Wolf Greenfield & Sacks P.C.
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