Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-03-27
2004-08-24
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S109000, C522S111000, C522S112000, C522S090000, C522S097000, C522S096000, C525S127000, C525S131000, C525S450000, C525S454000, C525S455000, C525S293000, C525S298000, C525S301000, C428S423100, C428S522000
Reexamination Certificate
active
06780897
ABSTRACT:
The present invention relates to novel solid compositions which contain bonds which can be activated with actinic radiation and comprise at least two materially different compounds. The present invention also relates to a novel process for preparing the novel compositions. The present invention additionally relates to novel coating materials, adhesives or sealing compounds which can be prepared using the new compositions. The present invention relates, furthermore, to a novel process for producing novel coatings, adhesive films, and seals on primed or unprimed substrates, using the novel coating materials, adhesives or sealing compounds. The present invention relates not least to novel primed or unprimed substrates which comprise novel coatings, adhesives and/or seals.
The coating or painting of primed or unprimed substrates with solid pulverulent coating materials, adhesives and/or sealing compounds which can be cured with actinic radiation is attracting more and more interest. The reason for this are advantages anticipated in terms of surface smoothness and the reduced thermal load on the substrates, which arise from the separation of the melting process and curing reaction as compared with coating materials, adhesives and sealing compounds which are curable by means of heat alone.
Here and below, actinic radiation means electromagnetic radiation such as X-rays, UV radiation, visible light or near IR light (NIR) or corpuscular radiation such as electron beams.
In the practical development of solid pulverulent coating materials, adhesives and/or sealing compounds curable with actinic radiation, especially powder coating materials, however, a number of problems arise.
The principal problem, especially in the case of radically curable systems based on (meth)acrylate-functionalized polyurethanes, which are particularly attractive from a performance standpoint, is the premature heat-initiated polymerization. This thermal polymerization leads to problems in the working-up of the solids into powder coating materials, for which, usually, multiple melting procedures are required. Even less attractive is the premature thermal polymerization that occurs when melting the powder coating materials onto the substrates, before irradiating them with actinic radiation. The fundamental advantage of radiation-curable powder coating materials over heat-curable powder coating materials, especially with regard to surface smoothness, that results from the separation of melting process from curing reaction, cannot be realized in this case.
The unwanted premature thermal polymerization may be prevented by adding sufficient amounts of polymerization inhibitors such as phenothiazine or hydroquinone; at the same time, however, the reactivity on exposure to actinic radiation is reduced to such an extent that the resulting exposure times were so long as to be of no industrial interest.
Further problems arise from the requirement for blocking resistance and low melting temperature of the solid radiation-curable powder coating materials, low viscosity of the melts, and good elasticity in the coatings. In the context of these problems, there exist multiple divergent functions: (meth)acrylate-functionalized polyurethanes with a low melting temperature and low melt viscosity are usually crystalline monomeric compounds or very low molecular mass oligomeric solids, which after crosslinking give rise to brittle films and coatings. (Meth)acrylate-functionalized polyurethanes of higher molecular mass normally give more elastic films that, however, have high melting temperatures and form highly viscous melts, which reduces the surface smoothness.
Moreover, the preparation of the (meth)acrylate-functionalized polyurethanes is comparatively complex and therefore expensive. In addition, the radiation-curable powder coating materials known to date leave something to be desired in terms of the scratch resistance, chemical resistance, and weathering stability of the coatings produced from them.
This also applies, mutatis mutandis, to the adhesives and sealing compounds.
Because of their economic and technological attractiveness, there has been no lack of attempts to develop the radiation-curable powder coating materials further.
For instance, the German patent application DE-A-24 36 186 or the U.S. Pat. No. 3,974,303 describe pulverulent and thermoplastic polymers which contain from 0.5 to 3.5 polymerizable unsaturated double bonds per 1000 molar weight, and their use as radiation-curable binders. Described specifically is a (meth)acrylate-functionalized polyurethane prepared in the melt from tolylene diisocyanate, 2-hydroxyethyl methacrylate, and trimethylolpropane in a molar ratio of 3:3:1. The (meth)acrylate-functionalized polyurethane has a melting point of around 65° C. and a polymerizable double bond content of 2.9 double bonds per 1000 molecular weight. No details, however, are given concerning the stability of the melt. The polyurethane can be used per se as an actinic radiation curable powder coating material. No details are given regarding the stability or mechanical quality of the coatings produced using it. Because of the high level of aromatic structures it contains, however, it is likely that the coatings produced from it are not stable to weathering but instead tend toward yellowing under the effect of sunlight.
The U.S. Pat. No. 4,208,313 describes unsaturated polymethacrylates having a low molecular weight and narrow molecular weight distribution, and mentions UV-curable powder coating materials, among others. The substances described, however, are solutions and/or oily liquids. There are no indications from this of a solution to the problems described above in the context of developing technically usable coating materials curable with actinic radiation, particularly powder coating materials.
The European patent application EP-A-0 636 669 describes mixtures of unsaturated polyesters or (meth)acrylate-functionalized polyacrylates, the polyacrylates being obtained in a conventional polymerization, and polyurethane crosslinking agents functionalized with vinyl ethers or (meth)acrylic esters. The examples disclose only mixtures of polyesters and vinyl ether urethanes. The vinyl ether urethanes are prepared in chloroform as solvent. No teaching is given on preparing olefinically unsaturated polyurethanes for overcoming the complex problems indicated above in the context of developing technically usable radiation-curable powder coating materials.
The European patent application EP-A-0 410 242 discloses polyurethanes containing (meth)acryloyl groups in an amount corresponding to from 3 to 10% by weight, based on the polyurethane, of ═C═C═ (molecular weight 24). These known polyurethanes have melting points or melting ranges in the temperature range from 50 to 180° C. (no further details are given). They are prepared using isophorone diisocyanate, 4,4′-diisocyanatodicyclohexylmethane, 4,4′-diisocyanatodiphenylmethane, its technical-grade mixtures with 2,4-diisocyanatodiphenylmethane, and, where appropriate, the higher homologues of these diisocyanates, 2,4-diisocyanatotoluene and its technical-grade mixtures with 2,6-diisocyanatotoluene (tolylene diisocyanate), and also biuret-, isocyanurate- or urethane-modified polyisocyanates based on these simple polyisocyanates. As far as the polyurethanes based on aromatic polyisocyanates are concerned, the above comments apply. Besides this, it is difficult to use these polyisocyanates as a basis for preparing polyurethanes which have a particularly narrow melting range, let alone a defined melting point. In particular, the use of polyisocyanates having an average functionality >2 leads to polyurethanes with an undesirably broad molecular weight distribution, making them of only limited usefulness in radiation-curable powder coating materials. Admittedly, some of the polyurethanes specified in the examples begin to soften at practicable temperatures of 85-95° C.; as a result of their high level of branching, however, the melt viscosity at the
Binder Horst
Blum Rainer
Bruchmann Bernd
Hintze-Bruening Horst
Paulus Wolfgang
BASF Coating AG
Keil & Weinkauf
McClendon Sanza L.
Seidleck James J.
LandOfFree
Solid substance mixture containing bonds that can be... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solid substance mixture containing bonds that can be..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solid substance mixture containing bonds that can be... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3314244