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CN-122029213-A - Electron beam curable compositions for producing coil coatings

CN122029213ACN 122029213 ACN122029213 ACN 122029213ACN-122029213-A

Abstract

The present invention relates to the use of an Electron Beam (EB) curable composition for producing an EB cured coil coating, wherein the composition comprises a cationically curable resin comprising a 1) an epoxide, a 2) a polyoxetane compound having at least two oxetane groups and a 3) a cationic initiator, wherein the weight ratio between epoxide a 1) and polyoxetane a 2) is in the range of 0.3-5.

Inventors

  • VERONIQUE MAURIN
  • P. Weinberg

Assignees

  • 佩什托普公司

Dates

Publication Date
20260512
Application Date
20241016
Priority Date
20231016

Claims (20)

  1. 1. Use of an Electron Beam (EB) curable composition for producing coil coatings, wherein the composition comprises a cationically curable resin comprising: a1 An epoxide compound is used to cure the epoxide compound, A2 A polyoxetane compound having at least two oxetane groups, and A3 A) a cationic initiator, Wherein the weight ratio between the epoxide a 1) and the polyoxetane a 2) is in the range of 0.3 to 5.
  2. 2. Use according to claim 1, wherein the weight ratio between the epoxide a 1) and the polyoxetane a 2) is in the range of 0.5-4, and preferably in the range of 1-3.5.
  3. 3. The use according to claim 1 or 2, wherein the composition comprises: a) 40 wt% -100 wt% of the cationically curable resin, wherein the cationically curable resin optionally further comprises at least one of the following compounds: a4 A mono-oxetane compound having at least one hydroxyl group, A5 A) an alkoxylated polyol(s), A6 A) a dendritic polymer polyol, A7 A) an epoxidized vegetable oil, B) 0 wt% -60% wt% of a free radical curable resin, wherein the free radical curable resin comprises B1 At least one (meth) acrylate monomer or oligomer, And optionally B2 A) a free radical photoinitiator, and (c) a free radical photoinitiator, Wherein weight percent is based on the total weight of the EB curable composition.
  4. 4. Use according to any one of claims 1-3, wherein the cationically curable resin comprises 25-wt-80-wt%, preferably 35-wt-80-wt% of the epoxide a 1).
  5. 5. The use according to any one of claims 1-4, wherein the cationically curable resin comprises 5 wt-60 wt%, preferably 15 wt-60 wt% of the polyoxetane a 2).
  6. 6. Use according to any one of claims 1-5, wherein the cationically curable resin comprises 0.1 wt-5 wt%, preferably 0.2 wt-4 wt% of the cationic initiator a 3).
  7. 7. The use according to any one of claims 3-6, wherein the cationically curable resin comprises 0 wt-20 wt%, preferably 0 wt-10 wt% of the monooxetane a 4).
  8. 8. Use according to any one of claims 3-7, wherein the cationically curable resin comprises 0 wt-20 wt%, preferably 0 wt-10 wt% of the alkoxylated polyol a 5).
  9. 9. Use according to any one of claims 3-8, wherein the cationically curable resin comprises 0 wt-20 wt%, preferably 0 wt-10 wt% of the dendrimer polyol a 6).
  10. 10. Use according to any one of claims 3-9, wherein the cationically curable resin comprises 0 wt-30 wt%, preferably 0 wt-20 wt% of the epoxidized vegetable oil a 7).
  11. 11. The use according to any one of claims 3-10, wherein the cationically curable resin comprises 25-wt-80-wt% of the epoxide a 1), 5-wt-60-wt% of the polyoxetane a 2), 0.1-wt-5-wt% of the cationic initiator a 3), 0-wt-20-wt% of the monooxetane a 4), 0-wt-20-wt% of the alkoxylated polyol a 5), 0-wt-20-wt% of the dendrimer polyol a 6) and 0-wt-30-wt% of the epoxidized vegetable oil a 7).
  12. 12. The use according to any one of claims 3-11, wherein the cationically curable resin comprises 35-wt-80-wt% of the epoxide a 1), 15-wt-60-wt% of the polyoxetane a 2), 0.2-wt-4-wt% of the cationic initiator a 3), 0-wt-10-wt% of the monooxetane a 4), 0-wt-10-wt% of the alkoxylated polyol a 5), 0-wt-10-wt% of the dendrimer polyol a 6) and 0-wt-20-wt% of the epoxidized vegetable oil a 7).
  13. 13. The use according to any one of claims 1-12, wherein the epoxide a 1) is a cycloaliphatic epoxide.
  14. 14. The use according to claim 13, wherein the cycloaliphatic epoxide a 1) is selected from the group consisting of 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, 3, 4-epoxy-1-methyl-cyclohexylmethyl-3, 4-epoxy-1-methylcyclohexane carboxylate, 6-methyl-3, 4-epoxycyclohexylmethyl-6-methyl-3, 4-epoxy-cyclohexane carboxylate, 3, 4-epoxy-3-methylcyclohexylmethyl-3, 4-epoxy-3-methylcyclohexane carboxylate and 3, 4-epoxy-5-methylcyclohexylmethyl-3, 4-epoxy-5-methylcyclohexane carboxylate.
  15. 15. The use according to any one of claims 1-14, wherein the polyoxetane compound a 2) is 3,3' -oxydimethylene-bis (3-ethyl) -oxetane.
  16. 16. Use according to any one of claims 1 to 15, wherein the cationic initiator a 3) is an onium salt, preferably an iodonium salt, more preferably iodonium hexafluoroantimonate.
  17. 17. The use according to any one of claims 3-16, wherein the monooxetane a 4) is 3-ethyl-3-hydroxymethyl-oxetane.
  18. 18. The use according to any one of claims 3-17, wherein the alkoxylated polyol a 5) is an ethoxylated polyol or a propoxylated polyol selected from the group consisting of trimethylol propane, ditrimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol and neopentyl glycol.
  19. 19. The use according to any one of claims 3-18, wherein the dendritic polymer polyol a 6) is a dendritic polyester polyol or a dendritic polyether polyol, or a blend thereof.
  20. 20. The use of claim 19, wherein the dendritic polyester polyol is a liquid fatty acid modified dendritic polyester polyol having 6 terminal hydroxyl groups.

Description

Electron beam curable compositions for producing coil coatings Technical Field The present invention relates to the use of an Electron Beam (EB) curable composition for producing coil coatings (coil coating), wherein the composition comprises a cationically curable resin comprising a 1) an epoxide, a 2) a polyoxetane compound having at least two oxetane groups, and a 3) a cationic initiator, wherein the weight ratio between epoxide a 1) and polyoxetane a 2) is in the range of 0.3-5. The invention also relates to a coil coating and a coated metal coil obtained by said use, the coated metal coil comprising a metal plate and a coil coating according to the invention. Background Coil coating is a process of applying a protective or decorative coating to a metal sheet that is continuously passed through a coating line. The sheet metal (typically steel or aluminum) is delivered in coil form and in one continuous process, the coil is unwound, pre-treated and pre-painted, then rewound and packaged at the end of the coating line for shipment to the end product manufacture. Coil coating is widely used in a variety of industries such as construction, automotive, packaging, and appliances (appliances). Conventional coil coating curing techniques involve heating the coated metal sheet in a gas oven at high temperatures (typically above 200 ℃) for several minutes. This process consumes a lot of energy and emits Volatile Organic Compounds (VOCs) and carbon dioxide (CO 2) into the atmosphere. In addition, conventional coil coating curing techniques require long coating lines with multiple ovens, which take up a lot of space and increase costs. Accordingly, the coil coating industry has begun to search for alternative coil coating curing techniques that can reduce energy consumption, environmental impact, and operating costs of coil coating. Achieving the challenging requirements of coil coating is a difficult balancing act. A high crosslink density is required to achieve good chemical resistance. However, high crosslink density generally results in low flexibility (flexibility), and the coating has a tendency to crack during molding. Examples of different known attempts to solve this conflict between the required high crosslink density and the desired high flexibility are by curing in two steps before and after shaping, or by applying the coating in several layers. Summary of The Invention The applicant notes that an alternative curing technique for the coil coating industry may be a radiation curing technique. The radiation curing causes the coating to cure immediately, eliminating the drying time. Furthermore, radiation curing can significantly reduce VOC and CO 2 emissions compared to solvent-borne and improve efficiency in industry by providing greater surface coverage (due to 100% solventless formulation) with the same amount of coating. Radiation curing techniques such as UV (ultraviolet) curing and EB (electron beam) curing have been successfully used in different paint and coating applications, especially UV curing for wood coatings. However, the challenges in coil coating are very high because non-porous substrate steel and aluminum make adhesion difficult. The coating must also be flexible in order to be able to form the final product after application. Unlike can coating (can coating) which is spray applied after metal can formation, coil coating is applied to the coiled metal sheet prior to the coiled metal sheet forming the final product. The potential advantages of radiation curing over conventional solvent-based thermoset coatings are enormous if applicable, due to the increased line speed, reduced energy consumption and the creation of solvent-free coatings resulting from the very short curing times. It is well known in the art that UV cationic curing has several advantages in terms of cured coating properties compared to free radical cured coatings. For example, cationic curing of epoxides occurs by ring-opening polymerization, which produces a considerably smaller shrinkage than radical curing of acrylates. Smaller shrinkage translates into better adhesion, especially for rigid substrates such as metals, where UV cationic curing of epoxides is typically used. However, it is difficult to find a suitable UV cationic curable coating for coil coating due to the need to combine high reactivity and good adhesion with high flexibility and the limitation of UV curing to relatively thin and UV transparent parts. It is also well known to use EB curing for free radical coating formulations, with the advantages of fast and deep curing, low energy consumption and high efficiency without the need for photoinitiators. EB-induced free radical curing of coatings generally needs to be performed in an inert environment in order to avoid oxygen inhibition (oxygen inhibition), and the coatings are limited by relatively low Tg, large shrinkage during curing, lack of flexibility, and low adhesion. Thus, 100% free radical system