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
2001-09-07
2003-04-29
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...
C427S372200, C427S385500, C524S590000, C524S591000, C524S839000, C524S840000
Reexamination Certificate
active
06555613
ABSTRACT:
The present invention relates to a novel reactive polyurethane and a novel polyurethane dispersion and to the use thereof for preparing solvent-free coating materials, especially basecoat and/or clearcoat or solid-color topcoat materials. The present invention further relates to a novel solvent-free coating material which comprises the novel polyurethane and the novel polyurethane dispersion. The present invention additionally relates to a novel process for producing multicoat coating systems on primed or unprimed substrates. The present invention relates not least to novel single-coat or multicoat coating systems, especially automotive OEM finishes, industrial coatings, including coil coatings and container coatings, and furniture coatings, and also to substrates which have these novel coatings.
In the context of the present invention, the term “solvent-free” denotes that the coating material in question is completely free from organic solvents or contains only the small amounts of organic solvents normally introduced by way of the starting products.
It is a general object to provide, for industrial processing, coating materials which release a minimum of volatile organic substances on processing.
Known are:
1. Solvent-free coating materials based on primary polymer dispersions, but which give rise to diffusion-impervious, stable, glossy coatings only in combination with dissolved cobinders and cosolvents.
2. Coating materials based on secondary dispersions, especially polyacrylate, polyester or polyurethane dispersions, but which again only give impervious, stable, glossy coatings with fractions of cosolvents and which, moreover, tend toward popping during application and film forming.
3. Solvent-free coating systems in the form of powder coatings or powder coating slurries, which are able to form impervious, smooth, glossy coatings, but whose preparation requires considerable effort and whose application, especially in the case of powder coating materials, requires special equipment.
It is an object of the present invention to provide a novel solvent-free coating material which no longer has the disadvantages of the prior art but instead may be processed and applied by the conventional application methods with substantially no emission of volatile organic substances and which after curing gives impervious, stable, glossy coatings.
The invention accordingly provides the novel reactive polyurethane (1) having a number-average molecular weight Mn of from 800 to 14000 daltons, a degree of branching of from 0.0 to 3.0 mol/kg, and an isocyanate functionality of from 2.0 to 6.0, which is preparable by reacting with one another
(1.1) at least one polyester and/or
(1.2) at least one polyether, both of which have at least two isocyanate-reactive functional groups, a molecular mass of from 400 to 2500 daltons and a degree of branching of from 0 to 3.5 mol/kg;
(1.3) at least one polyol having a molecular mass of from 62 to 400 daltons and a functionality of from 2 to 4 and/or
(1.4) at least one polyamine and/or
(1.5) at least one alkanolamine;
(1.6) at least one compound having at least one functional group capable of forming anions and at least one, in particular at least two, isocyanate-reactive functional groups;
(1.7) at least one polyisocyanate and/or
(1.8) at least one polyisocyanate adduct;
(1.9) at least one blocking agent for the isocyanate groups, which are eliminated again at a certain reaction temperature from the isocyanate groups they block, or are released again by a substitution reaction in the presence of the crosslinking agent (2); and
(1.10) at least one neutralizing agent for the anionic stabilization in the aqueous medium, which comprises or consists of organic and/or inorganic bases.
In the text below, the novel reactive polyurethane is referred to as the “polyurethane of the invention”.
The invention also provides the novel polyurethane dispersion which comprises at least one polyurethane of the invention in dispersion in an aqueous medium.
In the text below, the novel polyurethane dispersion is referred to as the “polyurethane dispersion of the invention”.
The invention further provides the novel solvent-free coating material, especially basecoat and/or clearcoat or solid-color topcoat material, which comprises at least one polyurethane of the invention and/or one polyurethane dispersion of the invention.
In the text below, the novel solvent-free coating material is referred to as the “coating material of the invention”.
The invention additionally provides a novel process for producing single-coat and multicoat coating systems, in which the coating material of the invention is used.
In the text below, the novel process for producing single-coat and multicoat systems is referred to as the “process of the invention”.
The invention provides, moreover, novel single-coat and multicoat systems produced using the coating material of the invention and/or with the aid of the process of the invention.
In the text below, the novel single-coat and multicoat systems are referred to as the “coating systems of the invention”.
The invention provides not least novel primed or unprimed substrates which carry the coating systems of the invention and which are referred to below as “substrates of the invention”.
In the light of the prior art it was surprising and unforeseeable for the skilled worker that the object on which the present invention is based might be achieved with the aid of the polyurethane of the invention or, respectively, the polyurethane dispersion of the invention, especially since the polyurethane dispersions known from the prior art still always necessarily include a comparatively high solvent fraction in order for their profile of properties to meet all of the requirements.
The polyurethane of the invention has a number-average molecular weight Mn of from 800 to 14000 daltons, preferably from 1500 to 6000 daltons. It has a degree of branching of from 0.0 to 3.0 mol/kg, preferably from 0.1 to 1.0 mol/kg. Its functionality, based on the blocked isocyanate groups, is from 2.0 to 6.0, preferably from 2.5 to 4.0 per mol.
The polyurethane of the invention is preparable from the starting products (1.1) to (1.10).
In accordance with the invention, at least one polyester is used as starting product (1.1) and at least one polyether is used as starting product (1.2). The starting products (1.1) and (1.2) may each be used individually or as a mixture to prepare the polyurethane of the invention. In accordance with the invention, the polyesters (1.1) are of advantage and are therefore used with preference.
The starting products (1.1) and (1.2) contain at least two isocyanate-reactive functional groups. Examples of suitable such functional groups are thio, amino, hydroxyl, or epoxide groups. In accordance with the invention, hydroxyl groups are advantageous and are therefore used with preference.
The polyesters (1.1) and polyethers (1.2) have molecular masses of from 400 to 2500 daltons, preferably from 800 to 1800 daltons, and a degree of branching of from 0 to 3.5 mol/kg.
The polyesters (1.1) for use in accordance with the invention are obtainable by reacting polycarboxylic acids, polyols and, if desired, monocarboxylic acids.
Examples of suitable polycarboxylic acids are aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, trimellitic acid or pyromellitic acid and also their ring-substituted alkyl derivatives; cycloaliphatic polycarboxylic acids such as tetrahydrophthalic acid, 1,2-cyclobutanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, hexahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid or tricyclodecanedicarboxylic acid, which may be used both in their cis forms and in their trans forms and also as a mixture of both forms; or acyclic polycarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicar
Heid Ingrid
Poth Ulrich
Röckrath Ulrike
BASF Coatings AG
Niland Patrick D.
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