Self-cleaning paint coating and a method and agent for producing the same

• US 7,544,411 B2
• Filed: 12/21/2001
• Issued: 06/09/2009
• Est. Priority Date: 02/10/2001
• Status: Expired due to Fees

• Current Assignee: Ferro GmbH (Vibrantz Technologies, Inc.)
• Original Assignee: Ferro GmbH (Vibrantz Technologies, Inc.)
• Inventors: Fritsche, Klaus-Dieter, Baumann, Martin, Ludwig, Stephan, Korbelarz, Dagmar, Poth, Lutz
• Primary Examiner(s): Jackson; Monique R
• Application Number:
  US10/467,261
• Publication Number:
  US 20040081818A1
• Time in Patent Office: 2,727 Days
• Field of Search: None
• US Class Current: 428/323
• CPC Class Codes: B05D 2601/20 used for non-pigmentation effect
• CPC Class Codes: B05D 3/0254 After-treatment
• CPC Class Codes: B05D 5/083 involving the use of fluoropolymers
• CPC Class Codes: B05D 7/52 Two layers
• CPC Class Codes: B08B 17/06 by giving articles subject to fouling a special shape or arrangement
• CPC Class Codes: B08B 17/065 the surface having a microscopic surface pattern to achieve the same effect as a lotus flower
• CPC Class Codes: C09D 5/28 for wrinkle, crackle, orange-peel, or similar decorative effects
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/259 Silicic material
• CPC Class Codes: Y10T 428/31 Surface property or characteristic of web, sheet or block

Abstract

A self-cleaning paint coating that exhibits the LOTUS EFFECT and an agent and a method for producing the same. The paint coating comprises a paint base coat and a topcoat. The topcoat includes structure-forming particles and is at least partially hydrophobic. The structure-forming particles have an average particle diameter of less than 100 nanometers (nm) and form elevations in the topcoat surface that are interspaced at a distance of less than 50 nm. The topcoat of the paint coating is formed from the agent. The agent contains a liquid medium, a hydrophobating agent dissolved in the liquid medium, and structure-forming particles suspended in the medium. The method of forming the paint coating comprises coating a substrate with the base coat, applying the topcoat agent to the partially cured or uncured base coat, and curing of the top coat, and if required, the base coat.

Claims

1. A self-cleaning lacquer coating, comprising:

a base lacquer layer; and

a top layer comprising particles and a first binder system overlaying the base lacquer layer, wherein the binder system binds the particles such that the top layer has a structured surface of elevations and depressions formed by the particles, wherein the particles have an average particle diameter of less than 100 nanometers, wherein the average height of, and the average distance between, the elevations are less than 50 nanometers wherein the surface or top layer is at least partly hydrophobic, and wherein the weight ratio of binder system to particles is from about 1;

50 to about 10;

1.

2. The self-cleaning lacquer coating of claim 1, wherein the structure-forming particles have an average diameter of at least 5 nanometers to less than 50 nanometers.

3. The self-cleaning lacquer coating of claim 1, wherein the particles comprise a material selected from the group consisting of metal oxides, mixed oxides, silicates, sulfates, phosphates, borates, carbon blacks, metal powders, metal sulfides, selenides, sulfoselenides, oxosulfides, metal nitrides, oxide-nitrides, organic polymers, and pigments, and combinations thereof.

4. The self-cleaning lacquer coating of claim 3, wherein the particles are metal oxides from the group consisting of SiO₂, TiO₂, Al₂O₃, ZrO₂ and SnO₂, and combinations thereof.

5. The self-cleaning lacquer coating of claim 1, wherein the base lacquer layer comprises a second binder system, wherein the second binder system is the same as the first.

6. The self-cleaning lacquer coating of claim 1, wherein

the binder system comprises constituents and

the particles comprise reactive groups, and

an in-situ polymerized fluorine-containing hydrophobizing agent,

wherein the hydrophobizing agent is bonded to at least one of the constituents and the reactive groups, thereby hydrophobizing at least a portion of the surface of the top layer.

7. The self-cleaning lacquer coating according to claim 1, wherein the binder system is formed from a resin selected from the group consisting of epoxy resins, polyester resins, polymethane resins, cellulose-based resins and vinyl resins.

8. A self-cleaning lacquer coating, comprising:

a base lacquer layer; and

a top layer comprising particles and a binder system overlaying the base lacquer layer, wherein the binder system binds the particles such that the top layer has a structured surface of elevations and depressions formed by the particles, wherein the particles have an average particle diameter of less than 100 nanometers, wherein the average height of, and the average distance between, the elevations are less than 50 nanometers and the surface or top layer is at least partly hydrophobic, and wherein the binder system and the particles are present in the top layer in a weight ratio of binder system to particles in the range of from about 1;

5 to about 5;

1.

9. A coating, comprising:

a first layer comprising a polymeric resin; and

a second layer overlaying the first layer and having an outer surface, wherein

the second layer comprises;

a binder;

a plurality of particles having an average diameter from about 7 nanometers to about 12 nanometers; and

a multifunctional halogenated silane or siloxane material;

wherein the weight ratio of binder to particles is from about 1;

50 to about 10;

1;

the outer surface having depressions and elevations that extend relative to the outer surface, the depressions and elevations being formed by the presence or absence in the outer surface of the plurality of particles, the average height of, and the average distance between, the elevations being less than 50 nanometers, and the multifunctional halogenated material being bound to the outer surface of the second layer through the multifunctional group and being oriented relative to the outer surface such that a halogen group on the silane or siloxane material can hydrophobize the outer surface, thereby reducing the roll-off angle relative to the outer surface to be less than about 3 degrees.

10. The coating according to claim 9, wherein:

the polymeric resin is selected from the group consisting of polyester-epoxy, polyester isocyanurate, polyester polyurethane, and epoxy;

the binder is selected from the group consisting of hydroxypropyl cellulose, chlorinated rubber, polyvinyl, acrylic, alkyd, melamine, phenolic, and polyester;

the plurality of particles comprise precipitated silica;

the multifunctional halogenated material is trifluorooctyltriethoxysilane or an oligomer thereof and

the roll-off angle relative to the outer surface is less than about 1 degree.

11. A process for producing a self-cleaning lacquer coating, comprising:

coating a substrate with a coating composition having a consistency of a liquid or of a paste so as to form a base lacquer layer;

determining a state of cure of the base lacquer as being cured, gelled, partly cured or non-cured;

selecting a coating process for coating the base lacquer layer with regard to the state of cure of the base lacquer layer;

coating the base lacquer layer with a liquid medium comprising;

a hydrophobizing agent being dissolved in the liquid medium, and structure-forming particles being suspended generally uniformly in the liquid medium, the particles having an average particle diameter of less than about 100 nanometers, and

a binder system operable to bind the particles to form a surface of a top layer wherein the surface is structured with elevations and depressions that extend relative to the top layer surface, and thereby to form the top layer overlaying at least a portion of the base lacquer layer;

wherein the average height of, and the average distance between, the elevations are less than 50 nanometers,

wherein the weight ratio of binder system to particles is from about 1;

50 to about 10;

1, and

wherein the surface or top layer is at least partly hydrophobic; and

curing the top layer, and if the base lacquer layer is gelled, partly cured or non-cured also curing the base lacquer layer.

12. The process of claim 11, further comprising at least partially evaporating solvents contained in the coating composition to effect at least partial gelling, at least partial drying, or at least partial curing of the base lacquer layer prior to applying the liquid medium to the base lacquer layer.

13. The process according to claim 11, further comprising heat treating the top layer at a temperature in a range of from about 100 degrees Celsius to about 250 degrees Celsius subsequent to the step of applying the liquid medium which forms the top layer to the base lacquer layer.

14. The process according to claim 13, wherein the heat treating temperature is in a range of from about 150 degrees Celsius to about 250 degrees Celsius.

15. A process for producing a self-cleaning lacquer coating, comprising:

coating a substrate with a coating composition having a consistency of a liquid or of a paste so as to form a base lacquer layer,

determining a state of cure of the base lacquer as being cured, gelled, partly cured or non-cured;

selecting a coating process for coating the base lacquer layer with regard to the state of cure of the base lacquer layer;

forming a top layer, by combining;

0.1 to 5 wt. % of structure-forming oxide particles having an average particle diameter of about 5 to about 50 nm;

0.1 to 10 wt. % of layer-forming binders or precursors;

0.1 to 5 wt. % of hydrophobizing agents selected from the group consisting of fluorine-containing alkoxysilanes and fluorine-containing alkoxysiloxanes; and

80 to 99.7 wt, % of a solvent selected from the group consisting of water, organic solvents, and combinations thereof;

coating the base lacquer layer with a liquid medium comprising;

a hydrophobizing agent being dissolved in the liquid medium, and structure-forming particles being suspended generally uniformly in the liquid medium, the particles having an average particle diameter of less than about 100 nanometers, and

a binder system operable to bind the particles such that a surface of the top layer is structured with elevations and depressions that extend relative to the top layer surface, wherein the top layer overlays at least a portion of the base lacquer layer; and

curing the top layer, and if the base lacquer layer is gelled, partly cured or non-cured also curing the base lacquer layer.

16. A process for producing a self-cleaning lacquer coating, comprising:

coating a substrate with a coating composition having a consistency of a liquid or of a paste so as to form a base lacquer layer,

determining a state of cure of the base lacquer as being cured, gelled, partly cured or non-cured;

selecting a coating process for coating the base lacquer layer with regard to the state of cure of the base lacquer layer;

coating the base lacquer layer with a liquid medium to form a top layer, the top layer comprising particles and a binder system, the liquid medium comprising a solvent, a hydrophobizing agent, and structure-forming particles, wherein the weight ratio of binder system to particles is from about 1;

50 to about 10;

1;

the hydrophobizing agent and the particles being dissolved or suspended in the solvent, the particles having an average particle diameter of less than about 100 nanometers, the solvent being operable to dissolve at least a surface portion of the base lacquer layer and cause at least a portion of the dissolved binder to migrate from the base lacquer layer into the top layer so that the top layer comprises a predetermined amount of migrated binder sufficient to bind the particles upon curing; and

curing the base lacquer layer and the top layer such that a surface of the top layer is structured with elevations and depressions that extend outward relative to the surface of the top layer, said elevations and depressions being formed by the particles, the average height of, and the average distance between the elevations being less than 50 nanometers, and the surface of the top layer being at least partially hydrophobic.