Process for the preparation of a multicoat finish, non-aqueous c

Details Process for the preparation of a multicoat finish, non-aqueous c Process for the preparation of a multicoat finish, non-aqueous c

1994-07-15

1996-07-09

Dudash, Diana

Coating processes

Applying superposed diverse coating or coating a coated base

Synthetic resin coating

427410, 4274121, 427387, 526271, 526273, B05D 136, B05D 700, C08F 2400, C08F12204

Patent

active

055343066

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for the preparation of a multicoat finish, in which layer, and subsequently
The invention also relates to nonaqueous coatings and autocrosslinkable polyacrylate resins.
The basecoat/clearcoat process described above is known and is employed in particular for the production of finishes, especially metallic finishes on car bodies (cf. eg. U.S. Pat. No. 3,639,147 and EP-A-38 127).
Nonaqueous transparent topcoats comprising a hydroxyl-containing resin and a polyisocyanate or an amino resin as crosslinking agent are usually employed in step (3) of the above-described process. Polyisocyanate-containing transparent topcoats must either be employed in the form of two-component coatings or using blocked polyisocyanates. The use of two-component coatings is laborious, and transparent finishes produced using blocked polyisocyanates have a tendency to yellow. Topcoats containing amino resins have an insufficient acid resistance and give off formaldehyde during baking.
The object of the present invention is to provide nonaqueous transparent topcoats which do not have the above-described disadvantages of the prior art. In addition, the new topcoats should give finishes having satisfactory properties even when they are applied with a high content of constituents which are nonvolatile under application conditions (i.e. with a low content of organic solvents).
Surprisingly this object is achieved in that, in step (3) of the above described process, a non-aqueous transparent topcoat is employed which comprises statistical average at least one epoxide group, at least one acid anhydride group and at least 0.2 tri-, di- or monoalkoxysilane groups per molecule, or a mixture of such autocrosslinkable polyacrylate resins, and
DE-A-40 08 343 describes transparent topcoats comprising polyacrylate resins which contain on statistical average at least one epoxide group and at least one silanol group and/or at least one hydrolyzable group bonded directly to a silicon atom per molecule. The coatings described in DE-A-40 08 343 contain in addition to the polyacrylate resins at least one other crosslinking agent. Crosslinking agents which can be employed are polyisocyanate compounds, amino resins and carboxylic acid compounds such as, for example, a resin or a compound having on average at least two carboxyl groups in the molecule, or a resin or a compound having on average at least one carboxylic acid anhydride group in the molecule. The topcoats described in DE-A-40 08 343 have the disadvantage that in many cases there are instances of incompatibility between the polyacrylate resins and the crosslinking agents, which leads to deterioration in the storage stability and the optical properties of the paint films.
The topcoats according to the invention are notable for a high degree of stability on storage. They give topcoat finishes which exhibit good scratch resistance, good resistance to acids and organic solvents, and high gloss, good DOI values and good leveling. In addition, these good properties are retained when the coatings are applied with a low content of organic solvents (less than 50% by weight). The transparent topcoats according to the invention preferably have a solids content of not less than 50% by weight (1 h, 130.degree. C.).
The autocrosslinkable polyacrylate resin (A) present as binder in the coatings employed according to the invention contains on statistical average at least one epoxide group, preferably 1.0 to 5.0, particularly preferably 1.0 to 3.0, and very particularly preferably 1.0 to 1.8 epoxide groups, at least one acid anhydride group, preferably 1.0 to 5.0, particularly preferably 1.0 to 3.0, and very particularly preferably 1.0 to 1.8, acid anhydride groups and at least 0.2 tri-, di- or monoalkoxysilane groups, preferably 0.2 to 2.0, particularly preferably 0.3 to 1.6, and very particularly preferably 0.4 to 1.0 tri-, di- or monoalkoxysilane groups per molecule. A mixture of such polyacrylate resins can also be employed as binder in the coatings employed according to the

REFERENCES:
patent: 3136736 (1964-06-01), Washburne et al.
patent: 3953644 (1976-04-01), Camelon et al.
patent: 4262072 (1981-04-01), Wendling et al.
patent: 4291135 (1981-09-01), Hohlein et al.
patent: 4415697 (1983-11-01), Peng et al.
patent: 4446283 (1984-05-01), Doi et al.
patent: 4499150 (1985-02-01), Dowblenko et al.
patent: 4564557 (1986-01-01), Ohgushi et al.
patent: 4732791 (1988-03-01), Blackburn et al.
patent: 4906677 (1990-03-01), Barsotti et al.
patent: 5369178 (1994-11-01), Miyazaki et al.
patent: 5376706 (1994-12-01), Barsotti et al.

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