Solvent-free pigmented formulation

Details Solvent-free pigmented formulation Solvent-free pigmented formulation

2002-05-06

2004-09-21

Reddick, Judy M. (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...

C524S424000, C524S425000, C524S427000, C524S442000, C524S444000, C524S446000, C524S556000, C524S492000, C524S493000

Reexamination Certificate

active

06794436

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a solvent-free pigmented formulation comprising
I) a binder based on at least one copolymer P in an aqueous polymer dispersion obtainable by free-radical aqueous emulsion polymerization of a monomer mixture containing
a) from 45 to 69.95% by weight of at least one monomer a) whose homopolymer has a glass transition temperature T
g
of less than 20° C.,
b) from 30 to 54.95% by weight of at least one monomer b) whose homopolymer has a glass transition temperature T
g
of more than 50° C.,
c) from 0.05 to 1.5% by weight of itaconic acid and/or its anhydride and/or its salts, as acidic monomer c), and
d) from 0 to 2% by weight of at least one further monomer d),
the sum of the % by weight of a) to d) being 100% by weight,
II) at least one pigment,
III) at least one pigment dispersant having an acid number to DIN 53402 of less than 600,
IV) if desired, an inorganic filler, and
V) customary auxiliaries.
The present invention further relates to a process for preparing the solvent-free pigmented formulation of the invention, and to its use as an emulsion paint.
BACKGROUND OF THE INVENTION
To reduce the burden on the environment, and from a workplace safety standpoint, it is desirable for coated compositions, especially those used in enclosed areas, such as emulsion paints, polymer dispersion plasters or tile adhesives, not to give off volatile, nonaqueous organic or inorganic components to their surroundings. In principle, this may be achieved in part by using aqueous polymer dispersions as binders for these coating systems.
However, conventional binders based on aqueous polymer dispersions generally still include small amounts of organic solvents. These are necessary in order to reduce the mean film formation temperature of the binders and so to ensure that the coating compositions can be processed even at low temperatures. The mean film formation temperature of the polymer binders may also be reduced by “internal plasticization”, i.e., by lowering the glass transition temperature of the binder polymer (see Ullmann's Encyclopaedia of Industrial Chemistry, 5th Ed. Vol. A21, p. 169). If the film formation temperature of the polymeric binder is too low, however, there is a risk that the coating compositions will have a poor pigment binding capacity and will lack adequate mechanical strength, and, moreover, will soil easily (see H. Rinno, farbe+lack, 99 (1993) 697 ff).
For reasons of cost it is advantageous for the binder to have the capacity to bind large amounts of fillers. Interior emulsion paints, for example, have pigment volume concentrations PVC (PVC=pigment volume/(pigment volume+binder volume); cf. Ullmanns Enzyklopädie der Technischen Chemie, 4th Ed. Vol. 15, p. 667) in the range from 50 to 85%. If the PVC tolerated for the binder is exceeded, the paint film no longer has adequate wet abrasion resistance. According to H. Warson (‘synthetic Resin Emulsions’, E. Benn Ltd., London, 1972, p. 776 ff.), polymers have a high pigment binding power if they include from 1 to 4% by weight of carboxyl-containing monomers. In the case of high-grade binders, indeed, the amount of these monomers is between 2.5 and 7% by weight. On the other hand, if the acid content is too high, there is a risk of the polymer becoming too soluble in water, with a resulting decrease in the wet abrasion resistance of the coating compositions.
The literature includes a range of examples of polymer dispersions suited for use as solvent-free binders for low-emission coating compositions. For example, EP-B-327 006 and EP-B-327 376 describe polymer dispersions based on vinyl esters where the copolymerized monomers include, in small amounts, silanes. EP-A-612 771 describes similar binder polymers, based on acrylic esters, containing in copolymerized form from 1 to 4% by weight of monomers containing carboxyl groups, and at least one silane monomer. Even minimal inclusion of vinyl silane monomers, however, represents a considerable increase in the costs of producing the binders. Moreover, the change in the properties of the binder on storage, owing to the hydrolysis of the silane groups, must be considered.
EP-A 810 274 discloses binders for solvent-free interior paints which may contain in copolymerized form up to 1% by weight of monomers containing acid groups, based on the overall weight of the monomers to be polymerized.
WO-A 94/21699 describes binders for solvent-free interior paints which may contain up to 5% by weight of copolymerized monomers containing acid groups, and which are prepared from a prepolymer having a very specific particle size.
WO-A 99/47611 relate to pigmented aqueous formulations whose binder includes a copolymer containing from 0.1 to 1.5% by weight of itaconic acid. In the examples of WO-A 99/47611, a salt of polyacrylic acid is used as a pigment dispersant.
EP-A 915 071 discloses copolymers containing from 0.2 to 5% by weight of itaconic acid. These copolymers are used to coat mineral moldings.
Moreover, WO-A 93/11181 and WO-A 98/33831 disclose itaconic acid copolymers suitable for preparing pigment pastes and, respectively, as binders for solvent-free interior paints.
The binders described in these publications are able only partly to meet the demands which they encounter in the context of their use for solvent-free pigmented formulations. For certain applications of solvent-free paint formulations it is necessary in particular to provide a binder providing an abrasion-resistant and scrubfast paint even when said paint formulations have a pigment volume concentration (PVC) of more than 75%.
SUMMARY OF THE INVENTION
It is an object of the present invention to remedy the disadvantages depicted and to develop a solvent-free pigmented formulation which, even at a high pigment volume concentration (PVC) of more than 75%, exhibits very good resistance to wet abrasion and wet scrubbing. The binder present within the solvent-free pigmented formulation ought to be characterized by a minimum film formation temperature of less than 10° C.
The invention accordingly provides a solvent-free pigmented formulation comprising
I) a binder based on at least one copolymer P in an aqueous polymer dispersion obtainable by free-radical aqueous emulsion polymerization of a monomer mixture containing
a) from 45 to 69.95% by weight of at least one monomer a) whose homopolymer has a glass transition temperature T
g
of less than 20° C.,
b) from 30 to 54.95% by weight of at least one monomer b) whose homopolymer has a glass transition temperature T
g
of more than 50° C.,
c) from 0.05 to 1.5% by weight of itaconic acid and/or its anhydride and/or its salts, as acidic monomer c), and
d) from 0 to 2% by weight of at least one further monomer d),
the sum of the % by weight of a) to d) being 100% by weight,
II) at least one pigment,
III) at least one pigment dispersant having an acid number to DIN 53402 of less than 600,
IV) if desired, an inorganic filler, and
V) customary auxiliaries.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The binder present in the pigmented formulation of the invention is constructed inter alia from the monomers a) and b), which feature different glass transition temperatures T
g
.
T
g
is the limit value of the glass transition temperature toward which said temperature moves, according to G. Kanig (Kolloid-Zeitschrift & Zeitschrift für Polymere, Vol. 190, p. 1, Equation 1), with increasing molecular weight; it is determined by the DSC method (Differential Scanning Calorimetry, 20 K/min, midpoint). The T
g
values for the homopolymers of most monomers are known and are listed, for example in Ullmann's Encyclopedia of Industrial Chemistry, VCH Weinheim, 1992, 5th Ed., Vol. A21, p. 169; further sources of glass transition temperatures of homopolymers include, for example, J. Brandrup, E. H. Immergut, Polymer Handbook, 1st Ed., J. Wiley, New York 1966, 2nd Ed. J. Wiley, New York 1975, and 3rd Ed. J. Wiley, New York 1989).
C
1
-C
n
alkyl groups below are linear or branched alkyl radicals having from 1 to n carbon atoms

Affiliated with

Also associated with

Rating

Solvent-free pigmented formulation does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Solvent-free pigmented formulation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solvent-free pigmented formulation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3207366