Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-06-06
2004-05-11
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S088000, C524S089000, C524S099000, C524S106000, C524S424000, C524S430000, C524S403000, C407S007000, C407S007000, C407S007000, C407S007000, C407S007000
Reexamination Certificate
active
06734231
ABSTRACT:
The invention relates to easily distributable pigment compositions, a process for their production and their use in pigmenting high molecular weight organic materials. Due to the excellent dispersibility of the pigment compositions of this invention, uniform distribution of pigment particles throughout the entire application media and, therefore, excellent color consistency is readily achieved. Products, for example solvent paints, spread coatings and powder coatings, comprising the stir-in pigment compositions show high color strength, high gloss and low haze as well as very good light fastness and weathering fastness.
In general, after being mixed into an aqueous or solventborne resin system, an organic pigment must be further dispersed prior to its final application in order to ensure that the organic pigment is homogeneously dispersed in the resin system. This additional dispersion step generally requires that the pigment be dispersed for a period of 2 to 48 hours using milling equipment, such as a vertical or horizontal bead mill or an attritor mill with milling media, such as glass beads or stainless steel balls. Since this additional dispersion step is both time-consuming and costly, the elimination of this step by using pigments that are adequately dispersed during a simple mixing step, without the need for the additional dispersing step, is a great advantage.
U.S. Pat. No. 5,075,366 discloses a masterbatch, i.e. a composition having a high content of a pigment or a dye and a polymer, consisting essentially of
(a) a resin such as an urea-aldehyde resin,
(b) a second component selected from the group of (b1) citric, acetylcitric or tartaric acid glycol polyalkyleneglycol esters and (b2) citric, acetylcitric or tartaric acid monoalcohol esters in admixture with polyalkyleneglycols, and
(c) dyes and/or pigments and/or additives.
The masterbatches of U.S. Pat. No. 5,075,366 are prepared by
(a) mixing the resin with the dye or pigment in a mixing apparatus,
(b) addition of the second component, which may contain additives, resulting in a mass,
(c) further mixing that mass to obtain a homogenous powder, and
(d) extrusion of the mass at a temperature not higher than 150° C.
The disadvantage of this masterbatch and its process is the additional use of a second component.
EP-A-947,540 claims a dry master batch comprising at least one pigment, wherein the masterbatch contains at least 80% by weight calculated on the weight of the mixture of particles of granulometry of lower than 1 &mgr;m of said of least one pigment dispersed in said carrier. The process of EP-A-947,540 uses at least one turbo-mixer and solvents, which are disadvantageous in an industrial process. Further, the product contains fine powder which has to be removed in order to obtain a satisfactory final product.
EP-A-902,061 discloses stir-in pigment compositions comprising 85 to 99.5 parts by weight of a pigment and 0.5 to 15 parts by weight of a vinylpyrrolidone polymer or copolymer.
MICROLEN® UA (Ciba Speciality Chemicals Inc.) is a mixture of 45 to 60% of an organic pigment, 2% of a dispersing agent (ethoxylated amine), 6.5 to 8.6% of polyethylene wax (LMWPE) and 46.5 to 29.4% of an urea-aldehyde resin (Laropal® A81).
Microlen® UA is produced by a wet process with a ball mill wherein PE-wax and dispersing agent have to be added and only a specific range of pigments can be processed. The final product is almost spherical shaped with a particle size of about 1-3 mm.
Therefore, the object of this invention is to provide a simple and environment-friendly process for the preparation of easily distributable pigment compositions, which show high color strength, high gloss and low haze when incorporated in high molecular weight organic materials, in particular solvent paints, spread coatings and powder coatings.
Accordingly, the present application is directed to a process for preparing a pigment composition comprising
a) mixing a pigment and a urea-aldehyde resin and/or a urea-ketone resin in a homogenizer or in the inlet (feeding) zone of the extruder, and
b) extruding the mixture obtained in step a), and
to a pigment composition obtainable by the process.
Due to the excellent dispersibility of the pigment compositions of this invention, uniform distribution of pigment particles throughout the entire application media and, therefore, excellent color consistency is readily achieved. Products, for example solvent paints, spread coatings and powder coatings, comprising the pigment compositions show high color strength, high gloss and low haze as well as very good light fastness and weathering fastness.
In step a) of the process according to the present invention the pigment and the urea-aldehyde resin and/or urea-ketone resin are mixed. The mixing can be carried out in a separate homogenizer or in the inlet (feeding) zone of the extruder. If the mixing is carried out in the inlet zone of the extruder the pigment and the resin can be jointly introduced at the beginning of the inlet zone or the resin is added at first and the pigment is added subsequently.
However, mixing of the components in a separate homogenizer is preferred. The homogenizer is not specially limited. In principal any device can be used, which provides proper mixing, i.e. a homogeneous distribution of the components, such as low-speed or high-speed mixers, tumblers or blenders. A tumbler is preferred.
If the mixing is carried out in a homogenizer, the pigment and the resin are generally mixed for 5 to 120 minutes, preferably 10 to 30 minutes, most preferably 15 minutes at a temperature ranging from 5 to the glass transition temperature of the resin, for example 50° C. in case of Laropal® A81, preferably 15 to 25° C.
The weight ratio of pigment to urea-aldehyde and/or urea-ketone resin is generally in the range of 40:60 to 90:10, preferably 50:50 to 80:20.
Urea-aldehyde resins and urea-ketone resins belong to the class of aminoplast resins and are curable condensation products of ureas and aldehydes, such as acetaldehyde, glyoxal and formaldehyde, in particular formaldehyde, or ketones. They are characterized by the following repeating unit
wherein R
1
, R
2
, R
3
and R
4
are independently of each other hydrogen or a organic group, like a linear or branched C
1-6
-alkyl group. Urea-aldehyde resins, in particular urea-formaldehyde resins, are preferred. Relevant information on raw materials used to produce urea-formaldehyde resins can be found in B. Meyer: Urea-Formaldehyde Resins, Addison-Wesley, London 1979. Most preferred are LAROPAL® A81 (BASF AG, softening point: 80-95° C.) and A101 (BASF AG, softening point: 95-110° C.).
In general any organic or inorganic pigment can be used in the process according to the present invention, if it is compatible with urea-formaldehyde and the urea-ketone resins and is processable with the process according to the present application. Depending on the application a crude or unfinished pigment can be used, but preferably the pigmentary form of the pigment is employed. Granules, as described, for example, in U.S. Pat. No. 5,985,019, can also be processed according to the inventive process.
Suitable organic pigments are, for example, described in W. Herbst, K. Hunger, Industrielle Organische Pigmente, 2
nd
revised edition, 1995. Especially suitable organic pigments for the present pigment compositions are organic pigments selected from the group consisting of azo, azomethine, methine, anthraquinone, phthalocyanine, perinone, perylene, diketopyrrolopyrrole, thioindigo, iminoisoindoline, dioxazine, iminoisoindolinone, quinacridone, flavanthrone, indanthrone, anthrapyrimidine and quinophthalone pigments, or a mixture or solid solution thereof; especially an azo, dioxazine, diketopyrrolopyrrole, quinacridone, phthalocyanine, indanthrone or iminoisoindolinone pigment, or a mixture or solid solution thereof.
Notable organic pigments useful in the present stir-in pigment compositions are those pigments described in the Color Index, including the group consisting of C.I. Pigment Red 202, C.I. Pigment Red 122, C.I. Pigmen
Creusen Gerardus Lambertus
Erkens Leonardus Johannes Hubertus
Hermans Robertus Josef Mathijs
Roox Nico Adelin Valentin
Ciba Specialty Chemicals Corporation
Sanders Kriellion A.
Stevenson Tyler A.
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