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CN-112399812-B - Non-stick coating and method for producing same

CN112399812BCN 112399812 BCN112399812 BCN 112399812BCN-112399812-B

Abstract

The invention relates to a non-stick coating for an article, comprising at least one adhesion promoter layer (V) arranged on the surface of the article and a cover layer (D) arranged on the adhesion promoter layer, wherein the adhesion promoter layer has a dry film layer thickness of 5 to 25 [ mu ] m, and wherein the cover layer has a dry film layer thickness of 10 to 65 [ mu ] m. In order to achieve an improved combination of non-stick effect and abrasion resistance, it is proposed that the cover layer contains 95 to 100 wt.% PTFE and optionally no more than 5 wt.% pigment, based on the total solids content of the cover layer, and is free of fluoropolymers that can be melt processed, and that the contained PTFE contains between 1 and 100 wt.% high molecular modified PTFE that contains less than 1 wt.% perfluoropropyl vinyl ether (PPVE) as a comonomer that acts as a modification and is obtained by emulsion polymerization. In a method for applying a non-stick coating, a layer of adhesion promoter in liquid form is applied as a first aqueous dispersion on the surface of an article and subsequently thermally dried, after which a cover layer in the form of a second aqueous dispersion is applied and the layers are connected to each other and to the surface of the article by subsequent drying and sintering, wherein the second dispersion is free of fluoropolymers that can be melt processed and free of low molecular PTFE.

Inventors

  • J. BRAND
  • H. G. Geisel
  • S. Lesch

Assignees

  • 工业漆股份公司
  • 工业漆股份公司

Dates

Publication Date
20260421
Application Date
20190710
Priority Date
20180710

Claims (19)

  1. 1. A non-stick coating for an article, wherein the non-stick coating has at least one adhesion promoter layer (V) arranged on the surface of the article and a cover layer (D) arranged on the adhesion promoter layer, wherein the adhesion promoter layer has a dry film layer thickness of 5 to 25 μm and wherein the cover layer has a dry film layer thickness of 30 to 65 μm, characterized in that the cover layer consists of 99 to 99.5 wt.% PTFE and 1 to 0.5 wt.% pigment, based on the total solids content of the cover layer, and is free of fluoropolymers that can be melt processed and free of low molecular PTFE, and the contained PTFE comprises between 1 and 100 wt.% of a high molecular modified PTFE comprising less than 1 wt.% perfluoropropyl vinyl ether (PPVE) as a comonomer that plays a modifying role and is obtained by emulsion polymerization, wherein the cover layer is free of acrylates due to the absence of acrylates added during its preparation.
  2. 2. The non-stick coating of claim 1, wherein said cover layer has a dry film layer thickness of 30 to 42 μm.
  3. 3. The non-stick coating according to claim 1 or 2, wherein the proportion of the polymer-modified PTFE in the cover layer is 2 to 50% by weight of the total PTFE in the cover layer.
  4. 4. The non-stick coating according to claim 1 or 2, wherein the proportion of the polymer modified PTFE in the cover layer is 4 to 6% by weight of the total PTFE in the cover layer.
  5. 5. The non-stick coating according to claim 1 or 2, wherein the fraction of the polymer modified PTFE in the cover layer is 5.5 wt.% of the total PTFE in the cover layer.
  6. 6. A non-stick coating according to claim 1 or 2, characterized in that the polymer modified PTFE has an average particle size of 150 to 250 nm.
  7. 7. A non-stick coating according to claim 1 or 2, wherein said adhesion promoter layer consists essentially of a high temperature resistant binder resin, a fluoropolymer, a pigment and a filler.
  8. 8. The non-stick coating of claim 7, wherein said binder resin is selected from the group consisting of PES (polyethersulfone resin) and PAI (polyamideimide).
  9. 9. A non-stick coating according to claim 1 or 2, wherein said adhesion promoter layer has a dry film thickness of 10 to 18 μm.
  10. 10. Use of a non-stick coating according to one of claims 1 to 9 for surface applications requiring higher abrasion resistance and good non-stick properties.
  11. 11. An article having a surface provided with a non-stick coating according to any one of claims 1 to 9.
  12. 12. The article of claim 11, wherein the article is a cooker or other commodity.
  13. 13. A method for applying a non-stick coating according to one of claims 1 to 9, wherein the layer of adhesion promoter to be formed in liquid form is applied as a first aqueous dispersion on the surface of the article and is subsequently dried at 60 to 110 ℃ for 5 to 15 minutes, and wherein a cover layer in the form of a second aqueous dispersion is subsequently applied on the pre-dried adhesion promoter layer and the layers are connected to each other and to the surface of the article by subsequently drying and sintering or melting at 410 to 430 ℃, characterized in that the second aqueous dispersion is free of fluoropolymers that can be melt processed and free of low-molecular PTFE, wherein the second aqueous dispersion is free of acrylic esters.
  14. 14. The method of claim 13, wherein said cover layer is applied at a dry film layer thickness of no more than 30 to 42 μm.
  15. 15. A method according to claim 13 or 14, wherein the proportion of polymer-modified PTFE in the second aqueous dispersion is from 2 to 50% by weight of the total PTFE in the second aqueous dispersion.
  16. 16. A method according to claim 13 or 14, wherein the proportion of polymer-modified PTFE in the second aqueous dispersion is 4 to 6% by weight of the total PTFE in the second aqueous dispersion.
  17. 17. A method according to claim 13 or 14, wherein the proportion of polymer modified PTFE in the second aqueous dispersion is 5.5% by weight of the total PTFE in the second aqueous dispersion.
  18. 18. A process according to claim 13 or 14 wherein the modified PTFE of the macromolecules in said second aqueous dispersion has an average particle size of 150 to 250 nm.
  19. 19. A method according to claim 13 or 14, wherein said adhesion promoter layer is applied in a dry film layer thickness of no more than 10 to 18 μm.

Description

Non-stick coating and method for producing same Technical Field The present invention relates to a PTFE non-stick coating having improved non-stick properties after intense wear, an article having such a non-stick coating, a method of manufacturing a non-stick coating and the use of a non-stick coating in the manufacture of cooking, frying and kitchen equipment or other applications requiring non-stick effects and high wear resistance. Background Organic fluoropolymer coatings exhibit good non-stick properties due to their lower surface energy and higher heat resistance due to higher C-F binding energy. These coatings find widespread use, in particular, as non-stick coatings for kitchen appliances. Non-stick coatings made of fluoropolymers are mostly applied in multiple layers on a substrate. The multi-layer fluoropolymer coating generally includes an adhesion promoter layer and a cover layer, and optionally one or more intermediate layers. Multilayer non-stick coatings made of fluoropolymers have been known for many years. The adhesion promoter layer of such systems is typically composed of one or more heat resistant organic binder resins and one or more fluoropolymers together with various pigments and fillers. The intermediate layer mainly comprises fluoropolymer, minor proportions of effect pigment, filler and film-forming auxiliary, while the cover layer almost consists of fluoropolymer, in particular of high-molecular PTFE obtained by emulsion polymerization of TFE from aqueous dispersion, or of high-molecular PTFE obtained by emulsion polymerization of TFE from aqueous dispersion, and minor proportions of fluoropolymer that can be melt-processed, in order to ensure as good non-stick properties of the cover layer as possible. In order to improve the abrasion resistance of the multilayer PTFE non-stick coating, hard inorganic fillers are mostly used. Thus, for example, US 5,250,356 describes a multilayer system comprising an adhesion promoter layer consisting of PTFE, PFA and PAI reinforced by fine (feinteilig) alumina, an intermediate layer consisting of PTFE, PFA and fine alumina and a cover layer consisting of pure PTFE. EP 1016466 describes a multilayer ceramic-reinforced non-stick coating, wherein the base layer contains ceramic particles, but which are so large that they protrude from the cover layer and thus prevent the wear load of the cover layer. US 6,761,964 describes a multilayer non-stick coating comprising a base layer made of a fluoropolymer, an adhesion promoter polymer and larger inorganic hard material particles anchored in the base layer and extending into the next intermediate layer consisting of the fluoropolymer and smaller ceramic filler particles, and comprising a cover layer consisting of only the fluoropolymer. EP 2001949 describes a three-layer non-stick coating in which the base layer and the cover layer do not contain >10 μm ceramic particles and the intermediate layer contains at least 3 wt.% of >10 μm ceramic particles and a fluoropolymer. If these systems are worn, they mostly exhibit poor non-stick properties on the worn surface, since the filler-free cover layer wears rapidly due to the small cover layer dry film layer thickness and thus exposes an intermediate layer with filler, which exhibits poorer non-stick properties than a cover layer which usually consists only of fluoropolymers. EP 2342279 describes a fluoropolymer coating composition with improved abrasion resistance applied on an adhesion promoter layer or at least one intermediate layer reinforced by alumina. The unfilled coating described consists of acrylate (film-forming aid), cerium ethylhexanoate (catalyst for film-forming aid combustion) and a fluoropolymer composition. The fluoropolymer composition here consists of 30-96% by weight (based on the total solid content of the fluoropolymer of the coating) of high molecular weight PTFE in the form of an aqueous dispersion having a number average molecular weight (Mn) of at least 500000, wherein the high molecular weight PTFE comprises less than 1% of modifying comonomer and the fluoropolymer composition further comprises a low molecular or low molecular weight PTFE in the form of an aqueous dispersion having a content of 4-70% by weight (based on the total solid content of the fluoropolymer of the coating) and having a first melting point of 335 ℃ or lower and the fluoropolymer composition comprises the fluoropolymer in the form of an aqueous dispersion that can be melt processed. The disclosed high molecular PTFE and the mentioned low molecular PTFE are obtained here by emulsion polymerization of TFE. The improved wear value of such coatings is due to the presence of low molecular PTFE and fluoropolymers (e.g., PFA) that can be melt processed. A layer thickness of about 8 μm is disclosed for the base layer and a layer thickness of about 25 μm is disclosed for the cover layer. WO2012/092414 describes aqueous dispersions of fluoropolymers that cannot be mel