Process for producing structured coatings
The present invention, relates, to a process, for producing structured coatings, in which a coating composition comprising at least one inorganic binder, at least one oxide pigment which, after addition of a mixture consisting of 15 ml of 1 M oxalic acid and 15 ml of 20% aqueous hydrochloric acid based on 1 g of substance, under standard conditions, leads to a temperature rise of at least 4° C., and at least one solvent is applied to a substrate, the resulting coating composition film is partially coated with a photoresist and the substrate coated with the coating composition and the photoresist is treated with an acid, to the structured layers obtainable by the process and to the use thereof.
1. A process for producing a structured coating, comprising:
applying
a. a coating composition comprising
i. at least one inorganic binder,
ii. at least one oxide pigment which, after addition of a mixture consisting of 15 ml of 1 M oxalic acid and 15 ml of 20% aqueous hydrochloric acid based on 1 g of substance, under standard conditions, leads to a temperature rise of at least 4° C., and
iii. at least one solvent
to a substrate, to obtain a coating composition film on the substrate,
b. partially coating the resulting coating composition film with a photoresist, and
c. treating the substrate coated with the coating composition film and the photoresist with an acid resulting in a leaching out of said at least one oxide pigment from said coating composition film leaving a leached layer.
2. The process according to claim 1 , wherein the inorganic binder has the generic formula Si a R 1 b O c (OR 2 ) d with a≥2, b≥0, c≥1, d≥5 and R 1 and R 2 =organic radical.
3. The process according to claim 1 , wherein the pigment is a pigment based on a mixed oxide of a (semi)metal in more than one oxidation state and/or a pigment based on at least two mixed oxides of at least two (semi)metals each in one or more oxidation states.
4. The process according to claim 3 , wherein said pigment is a mixed iron-manganese oxide.
5. The process according to claim 4 , wherein said pigment is a copper-containing mixed iron-manganese oxide.
6. The process according to claim 5 , wherein the mixed iron-manganese oxide is obtainable via a calcination of manganese(II) oxide, manganese(III) oxide, iron(II) oxide and iron(III) oxide and copper(II) oxide.
7. The process according to claim 6 , wherein the pigment is assigned to the group of pigments having the Colour Index designation Pigment Black 26.
8. The process according to claim 1 , wherein a proportion of oxide pigment, based on the total mass of the composition, is 10%-50% by weight.
9. The process according to claim 1 , wherein the at least one solvent is selected from the group consisting of an alcohol, an alkyl ester, an alkoxy alcohol, an alkoxyalkyl ester and mixtures thereof.
10. The process according to claim 1 , wherein the acid used is aqueous oxalic acid in a concentration of 0.3 to 2.5 mol/l, aqueous hydrochloric acid 3.0-12.0 mol/l or mixtures having proportion by volume ratios of 1:2 to 2:1 of 1 M aqueous oxalic acid and 6 M aqueous HCl.
11. The process according to claim 1 , wherein after the acid treatment
a. the photoresist is removed, and
b. the coating composition is cured.
12. The process according to claim 1 , wherein after the acid treatment
a. a portion of said coating composition film which is not coated with said photoresist is removed partially or completely,
b. the photoresist is removed, and
c. the coating composition is cured.
13. The process according to claim 1 , wherein as a result of acid treatment portions of said coating composition film exposed to acid becomes transparent.
14. The process according to claim 1 , wherein as a result of acid treatment, portions of said coating composition film exposed to acid become free of oxide pigment.
15. The process according to claim 1 , wherein as a result of acid treatment portions of said coating composition film exposed to acid are not etched.