Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-11-03
1999-12-21
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525386, C08F 814
Patent
active
06005056&
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
The invention relates to a modified acrylic copolymer and its use for lacquers with increased gloss.
The principal objective of the manufacturers of lacquers is a decorative attractive high gloss lacquer which simultaneously protects the substrate being coated. These requirements are particularly demanding in the motorcar industry. So far, the increase of gloss has been achieved by adding gloss additives or also leveling additives. However, these additives are disadvantageous in that they exude and thus, considerably impair the repainting characteristics as a result of a loss of adhesiveness. Moreover, these conventional lacquers gave poor results in humidity condensation tests.
Object of the present invention is to provide an acrylic copolymer modified in such a manner to allow its use, for example, for the production of coating compositions which, as compared to corresponding coating compositions made of unmodified acrylic copolymers, are characterized by higher gloss and higher resistance to chemicals as well as a weathering resistance adapted to the requirements set on clear coats in the motorcar industry.
Coating compositions of the kind are used in particular as clear coats in the motorcar industry.
This problem is solved by the invention by an acrylic copolymer obtained by modifying an epoxy groups-containing copolymer by a carboxylic group-containing polycycloaliphatic substance having at least two cycles, in particular at least three cycles and a refractive index at 20.degree. C. of at least 1.460.
A carboxyl group-containing polycycloaliphatic compound according to the present invention is a substance or a compound having a polycarbocyclic structure or partial structure, i.e. the cycles are only carbocycles.
Particularly suitable polycycloiliphatic compounds can be tricycloaliphatic monocarboxylic acids selected from the group of hydrogenated acids of natural resins, e.g. commercial products such as "Foral AX-E" of the Hercules BV company; adamantane carboxylic acids and tricyclic monocarboxylic acids derived from dicyclopentadiene, such as, e.g. tricyclodecane derivatives having a carboxyl group (TCD carboxylic acids), in particular tricyclo[5.2.1.0..sup.2,6 ]-clecane-8-carboxylic acid, preferably tetrahydroabietic acid.
In respect of the interrelation between refractive index and gloss, it is referred to the article of Juergen H. Braun in JOURNAL OF COATINGS TECHNOLOGY, Vol. 63, No. 799, August 1991.
In connection with the interrelation between refractive index and temperature, it is referred to Organikum, author collective, VEB Deutscher Verlag der Wissenschaften, 16th edition, Berlin 1986, pages 76 et seq.
For substances that are not liquid at 20.degree. C., the refractive index can be determined at elevated temperature by means of a thermo regulated Abbe refractometer with the light of the sodium D-line .lambda.=589 nm. The following applies as increment for the temperature correction: addition of 5.times.10.sup.-4 units per .degree. C.
In a further embodiment of the invention, the mol ratio of carboxylic group to epoxy group is between 0.5 to 1.0, preferably between 0.8 and 1.0.
The modified aciylic copolymers can be obtained by reacting an epoxy groups-containing acrylic copolymer, having more than one epoxy group per average molecular weight with the claimed modifying agents at elevated temperature, e.g. from 60 to 200.degree. C., preferably from 120 to 170.degree. C. The reaction can be conducted in the melt or in the presence of organic solvents, such as usually used in the manufacture of paints or resins, e.g. alcohols, e.g., methoxypropanol, butanol, aromatic hydrocarbons, e.g. xylol, crude oil distillates comprising mainly alkylbenzenes, esters, e.g. butyl acetate, methoxypropyl acetate, ketones, e.g. butanonc, methylisobutyl ketone, and mixtures thereof. If desired, conventional catalysts can likewise be used for the catalysis of the epoxy/carboxy reaction, e.g. alkali metal hydroxides, e.g. lithium hydroxide monohydrate, tertiary amines, e.g. triethylamine, N,N-benzy
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Masonne Matthias
Neis Stephan
Bollig & Kemper KG
Lipman Bernard
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