Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
2002-11-25
2004-06-01
Cameron, Erma (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S385500, C528S045000
Reexamination Certificate
active
06743484
ABSTRACT:
The present invention relates to novel reactive compositions. The present invention also relates to the use of the novel reactive compositions as coating materials, adhesives and sealing compounds. The present invention further relates to a novel process for preparing coatings, adhesive layers, and seals, which process can be carried out with no emissions.
Blocked polyisocyanates and processes for their preparation have been known for a long time. Reference is made, for example, to U.S. Pat. No. 4,444,954 A. The blocked polyisocyanates are preferably used as crosslinking agents in externally crosslinking reactive compositions, especially coating materials, adhesives, and sealing compounds.
The use of propargyl alcohol as blocking agents for polyisocyanates is known from German Patent Applications DE 38 09 695 A 1, DE 39 32 816 A 1 or DE 41 42 734 A 1. The polyisocyanates, partially blocked with propargyl alcohol, are incorporated through the reaction of free isocyanate groups into binders, which become self-crosslinking as a result. The polyisocyanates fully blocked with propargyl alcohol serve as crosslinking agents in externally crosslinking reactive compositions.
Externally crosslinking is a term used to refer to those coating materials, adhesives, and sealing compounds in which one variety of the complementary reactive functional groups which bring about crosslinking is present in a binder and the other variety in a hardener, curing agent or crosslinking agent. Self-crosslinking coating materials, adhesives, and sealing compounds are those in which the complementary reactive functional groups are present in one constituent. For further details, reference is made to Rompp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, “Curing”, pages 274 to 276, especially page 275, bottom.
The crosslinking of the blocked polyisocyanates known from German Patent Application DE 38 09 695 A 1 is catalyzed by catalysts, such as salts or complexes of metals, such as lead, zinc, iron, tin, manganese, and bismuth, for example. Preferred metal catalysts in this context are lead compounds, such as lead carboxylates having from 1 to 10 carbon atoms, or tin compounds, such as dibutyltin diacetate, dibutyltin dilaurate or dibutyltin oxide. As is known, these catalysts accelerate the elimination of blocking agents from the blocked polyisocyanates and the reaction of isocyanate-reactive functional groups in the binders and/or reactive diluents with the formation of urethane, thiourethane and/or urea groups.
The disadvantage of this type of crosslinking is that volatile organic compounds are released which, if they remain in the resultant coats, adhesive films and seals, may adversely affect the profile of performance properties of said coats, adhesive films and seals or, if they depart the resultant coats, adhesive films and seals, constitute unwanted organic emissions.
Furthermore, the coats, adhesive films, and seals which comprise urethane, thiourethane and/or urea groups in their three-dimensional network, as far as pigmentability, leveling, hardness, flexibility, scratch resistance, chemical resistance, weathering stability, adhesion, and gloss are concerned, offer distinct advantages over coats, adhesive films, and seals based on a different crosslinking chemistry.
It would therefore be highly desirable to have available a reactive composition which could be cured without emission to give a three-dimensional network containing urethane, thiourethane and/or urea groups.
It is true that reactive compositions which may be cured without emissions and give three-dimensional networks containing urethane and/or urea groups have been known for a long time. However, these are straight two-component or multicomponent systems in which unblocked polyisocyanates are used as crosslinking agents. These cure even at room temperature. However, until shortly before the application, the high reactivity of the crosslinking agents means that they have to be stored separately from the other constituents of the composition, necessitating a more complex technology and logistics. Furthermore, this makes it very much more difficult, if not impossible, to prepare powder coating materials and powder coating dispersions (powder slurries).
It would therefore be particularly desirable to have available a one-component system which can be cured without emissions and where the crosslinking agents need not be stored separately from the other constituents.
European Patent Application EP 0 852 252 A1 discloses epoxy resins containing propargyl groups and amino groups. The propargyl-containing epoxy resins are used to prepare cathodically depositable electrodeposition coating materials, which are selfcrosslinking via amino groups and propargyl groups or via the acetylenically unsaturated bonds. The cathodically depositable electrodeposition coating material further comprises a constituent such as, for example, tetrabutylammonium bromide which, following its activation by the electrolysis, catalyzes the thermal curing of the deposited electrodeposition coating film. As a result, the electrodeposition coating film may be cured at comparatively low temperatures. If the electrodeposition coating material, however, is not applied electrophoretically but instead, for example, by knife-coating onto a substrate, the resultant coating film does not crosslink below 200° C.
It is an object of the present invention to provide new reactive compositions, especially coating materials, adhesives, and sealing compounds, particularly one-component coating materials, adhesives, and sealing compounds, which match if not exceed the technological profile of properties of the known reactive compositions and may be cured, moreover, without emissions. It should be possible to provide the new reactive compositions in the form of finely divided powders, powder slurries, aqueous solutions or dispersions, organic solutions or dispersions, or as essentially water-free and solvent-free liquid systems (100% systems).
It is another object of the present invention to find a new process for the thermal curing of reactive compositions comprising blocked polyisocyanates as crosslinking agents that proceed without emissions.
Furthermore, the new process and the new reactive compositions ought to make it possible to postcrosslink the resultant new coats, adhesive films, and seals with actinic radiation.
It is not least an object of the present invention to provide new coats, adhesive films, and seals which have a profile of performance properties which matches if not exceeds that of the known coats, adhesive films, and seals.
Found accordingly have been the novel reactive compositions which consist of or comprise
(A) at least one polyisocyanate whose isocyanate groups have been partially or fully blocked with propargyl alcohol,
(B) at least one constituent having on average at least two isocyanate-reactive. functional groups in the molecule, and
(C) at least one catalyst which catalyzes the addition reaction of the isocyanate-reactive functional groups of (B) with the acetylenically unsaturated triple bond of the propargyl groups,
and which are referred to below as “compositions of the invention”.
Also [lacuna] has been the novel process for producing coatings, adhesive films, and seals by
(I) applying coating materials, adhesives, and sealing compounds which consist of or comprise at least one composition of the invention onto and/or into a substrate, and
(II) thermally curing the resultant films and/or compositions,
In the text below, the novel process for producing coats, adhesive films, and seals is referred to as “curing process of the invention”.
Further subject matter of the invention will emerge from the description.
In the light of the prior art it was surprising and unforeseeable to the skilled worker that the complex of objects on which the present invention was based could be solved through the compositions as claimed in the invention. It was also surprising that specifically the compositions of the invention make it
Ott Gunther
Reuter Hardy
Röckrath Ulrike
Schön Georg
Woltering Joachim
BASF Coatings AG
Cameron Erma
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