Method for producing adhesive surface coatings

• US 6,548,121 B1
• Filed: 01/09/2002
• Issued: 04/15/2003
• Est. Priority Date: 10/28/1998
• Status: Expired due to Term

• Current Assignee: Ciba Specialty Chemicals Corp (BASF SE)
• Original Assignee: Ciba Specialty Chemicals Corp (BASF SE)
• Inventors: Köhler, Manfred, Kunz, Martin, Bauer, Michael, Misev, Ljubomir
• Primary Examiner(s): CAMERON, ERMA C
• Application Number:
  US09/830,485
• Time in Patent Office: 461 Days
• Field of Search: 427/509, 427/512, 427/513, 427/517, 427/518, 427/519, 427/520, 427/535, 427/536, 427/538, 427/551, 427/553, 427/554, 427/556, 427/407.2, 427/409, 427/412, 427/412.1, 427/419.2, 427/491, 427/534, 427/552, 427/555, 427/558
• US Class Current: 427/509
• CPC Class Codes: B05D 3/062 Pretreatment
• CPC Class Codes: B05D 3/10 by other chemical means
• CPC Class Codes: B05D 3/142 Pretreatment
• CPC Class Codes: C23C 14/024 Deposition of sublayers, e.g. to promote adhesion of the coating C23C14/027 takes precedence

Abstract

The invention relates to a process for the production of strongly adherent coatings on an inorganic or organic substrate that comprises, in a first step

a) subjecting the inorganic or organic substrate to the action of a low-temperature plasma discharge, a corona discharge, high-energy UV radiation or electron radiation, then discontinuing the radiation or discharge; in a further step

b) under vacuum or at normal pressure, applying one or more photoinitiators containing at least one ethylenically unsaturated group to the inorganic or organic substrate, and allowing reaction with the free-radical sites formed there; and

c1) coating the substrate so precoated with photoinitiator with a composition comprising at least one ethylenically unsaturated monomer or oligomer, and curing the coating by means of UV/VIS radiation or

c2) depositing a metal, semi-metal oxide or metal oxide from the gaseous phase, in the presence of UV light, on the substrate so precoated with photoinitiator. The invention relates also to the use of photoinitiators having at least one ethylenically unsaturated group in the production of such layers and to the strongly adherent coatings themselves.

Claims

1. A process for the production of adherent coatings on an inorganic or organic substrate that comprises, in a first step

a) subjecting the inorganic or organic substrate to the action of a low-temperature plasma discharge, a corona discharge, high-energy UV radiation or electron radiation, then discontinuing the radiation or discharge;

in a further step

b) under vacuum or at normal pressure, applying one or more photoinitiators containing at least one ethylenically unsaturated group to the inorganic or organic substrate, and allowing reaction with the free-radical sites formed in step a); and

c1) coating the substrate so precoated with photoinitiator with a composition comprising at least one ethylenically unsaturated monomer or oligomer, and curing the coating by means of UV/VIS radiation or

c2) depositing a metal, semi-metal oxide or metal oxide from the gaseous phase, in the presence of UV light, on the substrate so precoated with photoinitiator.

2. A process according to claim 1, wherein the inorganic or organic substrate is in the form of a powder, a fibre, a film or a three-dimensional workpiece.

3. A process according to claim 1, wherein the inorganic or organic substrate is a thermoplastic, elastomeric, inherently crosslinked or crosslinked polymer, a metal oxide, a glass or a metal.

4. A process according to claim 1, wherein the photoinitiator is a compound of formula I or Ia

5. A process according to claim 4, wherein in the compounds of formula I or Ia (IN) is a photoinitiator base structure of formula (II) or (III)

R₁ is a group (A), (B) or (III)

 

—

CR₆R₇R₈ (B);

R₂ is hydrogen, C₁-C₁₂alkyl, halogen, the group (RG)—

A—

or, when R, is a group (A), two R₂ radicals in the ortho position relative to the carbonyl group together also are —

S—

R₃ and R₄ are each independently of the other C₁-C₆alkyl, C₁-C₆alkanoyl, phenyl or benzoyl, wherein the radicals phenyl or benzoyl are each unsubstituted or substituted by halogen, C₁-C₆alkyl, C₁-C₆alkylthio or C₁-C₆alkoxy;

R₅ is hydrogen, halogen, C₁-C₁₂alkyl or C₁-C₁₂alkoxy or the group (RG)—

A—

;

R₆ is OR₉ or

R₇ and R₈ are each independently of the other H, C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₁-C₁₂alkoxy, phenyl or benzyl or together are C₂-C₆alkylene;

R₉ is hydrogen, C₁-C₆alkyl or C₁-C₆alkanoyl;

R₁₀ is hydrogen, C₁-C₁₂alkyl or phenyl; and

X₁ is oxygen or sulfur.

6. A process according to claim 4, wherein in the compounds of formula I or Ia (IN) is a group

7. A process according to claim 4, wherein in the compounds of formula I or Ia

A is a spacer group —

Z—

[(A₁)_a—

Y]_c—

[(A₂)_b—

X]_d;

X, Y and Z are each independently of any other(s) a single bond, —

O—

, —

S—

, —

N(R₁₀)—

, —

(CO)—

, —

(CO)O—

, —

(CO)N(R₁₀)—

, —

O—

(CO)—

, —

N(R₁₀)—

(CO)—

or —

N(R₁₀)—

(CO)O—

;

A₁ and A₂ are each independently of any other(s) C₁-C₄alkylene, C₃-C₁₂cycloalkylene, phenylene, phenylene-C₁-C₄alkylene or C₁-C₄alkylenephenylene-C₁-C₄alkylene;

a, b, c and d are each independently of the others a number from 0 to 4; and

R₁₀ is as defined hereinbefore.

8. A process according to claim 7, wherein in the compounds of formula I or Ia A is a spacer group —

Z—

[(CH₂)_a—

Y]_c—

[(CH₂)_b—

X]_d—

in which X, Y, Z, a, b, c and d are as defined hereinbefore.

9. A process according to claim 4, wherein in the compounds of formula I or Ia

(RG) is R_cR_bC═

CR_a—

,

(RG′

) is

 

and

R_a, R_b and R_c are each H or C₁-C₆alkyl, especially H or CH₃.

10. A process according to claim 1, wherein at least one of the ethylenically unsaturated monomers or oligomers of the composition is a mono-, di-, tri- or tetra-functional acrylate or methacrylate.

11. A process according to claim 1, wherein the composition comprising at least one ethylenically unsaturated monomer or oligomer comprises at least one further photoinitiator or coinitiator for the curing by UV/VIS radiation.

12. A process according to claim 1, wherein the process pressure is from 10⁻

6 mbar up to atmospheric pressure.

13. A process according to claim 1, wherein there is used as plasma gas an inert gas or a mixture of an inert gas with a reactive gas.

14. A process according to claim 13, wherein N₂, He, Ar, Kr, Xe, O₂ and H₂O are used on their own or in the form a mixture.

15. A process according to claim 1, wherein the photoinitiator is applied by vaporizarion at a temperature of 20°

C. to 250°

C.

16. A process according to claim 1, wherein the deposited photoinitiator layer or the metal layer has a thickness ranging from that of a monomolecular layer up to 100 nm.

17. A process according to claim 1, wherein the plasma treatment a) is carried out for from 1 second to 300 seconds.

18. A process according to claim 1, wherein the deposition of the photoinitiator b) is carried out for from 1 second to 10 minutes.

19. A process according to claim 1, wherein process step b) is carried out immediately after, or within 10 hours of, process step a).

20. An adherent coating obtained in accordance with a process according to claim 1.