CN-121975393-A - Waterborne epoxy resin-based shop primer

Abstract

The present invention relates to an aqueous epoxy-based shop primer comprising a) a film-forming resin composition comprising i) an epoxy resin component, and ii) an aqueous carrier, and b) an aqueous curing system comprising an epoxy reactive curing agent, wherein the epoxy resin component comprises a bulk epoxy resin and a rubber modified epoxy resin, and wherein the shop primer is substantially free of zinc. The present invention also relates to an article comprising a metal substrate having at least one major surface, and a shop primer layer formed from the waterborne epoxy-based shop primer described above directly applied on the major surface.

Inventors

• JIANG CHAO
• XIE JIANNING
• ZHANG PING

Assignees

• 宣伟(广东)新材料有限公司

Dates

Publication Date

20260505

Application Date

20191204

Claims (19)

1. 1. An aqueous epoxy-based shop primer comprising: a) A film-forming resin composition comprising i) an epoxy resin component, and ii) an aqueous carrier, and B) An aqueous curing system comprising an epoxy-reactive curing agent; wherein the epoxy resin component comprises a main epoxy resin and a rubber modified epoxy resin, and Wherein the shop primer is substantially free of zinc.
2. 2. The waterborne epoxy-based shop primer of claim 1, wherein the rubber modified epoxy resin has an epoxy equivalent weight in the range of 450-620 g/eq.
3. 3. The waterborne epoxy-based shop primer of claim 1, wherein the rubber-modified epoxy resin has a glass transition temperature of 10 ℃ or less, preferably 0 ℃ or less.
4. 4. The waterborne epoxy-based shop primer of claim 1, wherein the rubber-modified epoxy resin is obtained by toughening bisphenol a-type epoxy resin with rubber molecules.
5. 5. The waterborne epoxy-based shop primer of claim 4, wherein the rubber molecules are selected from one or more of a carboxyl terminated nitrile rubber, a hydroxyl terminated nitrile rubber, a polysulfide rubber, a nitrile-isocyanate prepolymer, a hydroxyl terminated polybutadiene, a polyether rubber, a polyurethane rubber, and a silicone rubber.
6. 6. The waterborne epoxy-based shop primer of claim 4, wherein the bisphenol a-type epoxy resin has an epoxy equivalent weight in the range of 500-575 g/eq.
7. 7. The waterborne epoxy-based shop primer according to claim 1, wherein the rubber-modified epoxy resin is present in the form of a dispersion in an aqueous solvent, preferably having a solids content of 40-65% by weight.
8. 8. The waterborne epoxy-based shop primer of claim 1, wherein the bulk epoxy resin has an epoxy equivalent weight in the range of 400g/eq to 2500 g/eq.
9. 9. The waterborne epoxy-based shop primer of claim 1, wherein the host epoxy resin is selected from one or more of diglycidyl ethers of polyhydric phenols, diglycidyl ethers of polyhydric alcohols, and polyglycidyl ethers of phenolic resins.
10. 10. The waterborne epoxy-based shop primer of claim 9, wherein the host epoxy is a diglycidyl ether of a polyhydric phenol having the following structural formula (I): (I) Wherein, the D represents-S-, -SO 2 -、-CO 2 -, -CO-, -O-or a divalent C 1 -C 10 -alkylene group, Each Y independently represents halogen, or an optionally substituted monovalent C 1 -C 10 hydrocarbon group, Each m independently represents 0, 1,2,3 or 4, N is an integer from 0 to 4.
11. 11. The waterborne epoxy-based shop primer of claim 1, wherein the bulk epoxy is in the form of a waterborne epoxy emulsion.
12. 12. The waterborne epoxy-based shop primer of claim 11, wherein the waterborne epoxy emulsion has a solids content of 40-60 wt%.
13. 13. The aqueous epoxy-based shop primer of claim 1, wherein the aqueous vehicle comprises an alcoholic solvent, and the alcoholic solvent comprises ethanol, propanol, 1-methoxy-2-propanol, or any combination thereof.
14. 14. The waterborne epoxy-based shop primer of claim 1, further comprising a conductive filler, wherein the conductive filler comprises a phosphorus iron powder.
15. 15. The waterborne epoxy-based shop primer of claim 14, wherein the film-forming resin composition comprises, relative to the total weight of the film-forming resin composition: 22-25 wt% of the host epoxy resin; 5-8 wt% of the rubber modified epoxy resin; 4-7 wt% of the conductive filler; 25-31 wt% of the aqueous carrier, and 20-30% By weight of additional additives.
16. 16. The waterborne epoxy-based shop primer of claim 1, wherein the epoxy-reactive curing agent comprises an aliphatic polyamine, an aliphatic amine adduct, an amidoamine, an aminopolyamide resin, a cycloaliphatic amine, an aromatic amine, an araliphatic amine, a mannich base, a ketimine, a dicyandiamide, or any combination thereof.
17. 17. The aqueous epoxy-based shop primer according to any one of claims 1 to 16, wherein the shop primer is applied and cured in an amount to form a 20 micrometer dry paint film thickness, the resulting paint film exhibiting a water permeability of 0.3 ml or less when subjected to a water penetration test according to JG/T210-2018 and/or an oxygen permeability of 30 cm 3 /m 2 .24 h.0.1 MPa or less when subjected to an oxygen penetration test according to GB/T1038-2000.
18. 18. An article of manufacture comprising A metal substrate having at least one major surface, and A shop primer layer formed from the waterborne epoxy-based shop primer of any one of claims 1 to 17 directly coated on the major surface.
19. 19. The article of claim 18, wherein the metal substrate is selected from the group consisting of steel, iron, aluminum, zinc, and alloys thereof.

Description

Waterborne epoxy resin-based shop primer The application relates to a divisional application of an application patent application with the application date of 2019, 12 months and 04 days, the application number of 201911225745.7 and the name of waterborne epoxy resin-based shop primer. Technical Field The invention relates to a waterborne epoxy-based shop primer, in particular to a waterborne epoxy resin-based zinc-free shop primer with excellent corrosion resistance. Background Large metal objects such as cargo containers are typically assembled by welding together a plurality of individual components made of iron, steel or other conductive metals. To prevent corrosion of the components prior to assembly, the components may be cleaned (e.g., by grit blasting, grinding or other abrasive or ablative processes) and then coated with a temporary corrosion resistant primer. Thus, such temporary corrosion resistant primers (also known as shop primers) are important coatings that provide corrosion resistance to metal articles. At present, the epoxy zinc-rich paint is still one of important anticorrosive paints for ships, ocean engineering, steel structures and the like, and has excellent anticorrosive performance. The anticorrosion performance of the epoxy zinc-rich primer is realized due to the existence of a large amount of zinc powder in the system. The zinc is more active than iron and is easy to lose electrons, zinc powder and steel base materials form a primary battery, the electrode potential of the zinc is lower than that of iron, the zinc is an anode (commonly called a sacrificial anode), the iron is a cathode, current flows from zinc to iron, and metallic iron is cathodically protected, meanwhile, zinc-rich paint is continuously corroded in the application process, corrosion products, namely basic zinc carbonate, are deposited on zinc powder gaps and steel surfaces, the basic zinc carbonate is compact in structure and non-conductive, is a indissolvable stable compound, can block and shield the corrosion of corrosive media, has an anti-corrosion effect, and has unique self-repairing property. Therefore, the anticorrosion life of the coating system of the epoxy zinc-rich primer, the matched intermediate layer coating and the finishing paint can reach more than 15 years, and the epoxy zinc-rich primer is the most commonly used anticorrosion coating system of the current steel structure. However, because the zinc powder content in the zinc-rich primer is generally high and can reach 85% or 95%, a large amount of zinc overflows when a paint film of the zinc-rich primer is subjected to electric welding cutting flame operation, and generated steam brings serious harm to the health of operators, so that operators are easy to cause hot zinc diseases. In addition, conventional epoxy shop primers are solvent borne and aqueous systems often fail to meet applicable performance requirements and standards. With the increasing environmental awareness, the paint industry "oil-to-water" is a significant challenge. Thus, there is a need in the art for an aqueous zinc-free epoxy shop primer with good corrosion resistance. Disclosure of Invention The invention provides a waterborne epoxy resin-based shop primer, which comprises the following components: a) A film-forming resin composition comprising i) an epoxy resin component, and ii) an aqueous carrier, and B) An aqueous curing system comprising an epoxy-reactive curing agent; wherein the epoxy resin component comprises a main epoxy resin and a rubber modified epoxy resin, and Wherein the shop primer is substantially free of zinc. The present invention also provides an article comprising a metal substrate having at least one major surface, and a shop primer layer formed from the waterborne epoxy-based shop primer of the present invention directly coated on the major surface. Preferably, the metal substrate is selected from steel, iron, aluminum, zinc and alloys thereof. The inventors of the present application have surprisingly found that in the formulation of waterborne epoxy-based shop primers, the film-forming resin composition comprises an epoxy resin component comprising a host epoxy resin and a rubber-modified epoxy resin, as a result of which the resulting paint film can achieve excellent corrosion protection without zinc, which was previously difficult to predict in the present application. It is well known that most shop primers currently on the market that have excellent corrosion protection properties are corrosion protected by incorporating a large amount of zinc powder into their formulation so that the zinc powder "sacrifices" itself to slow the corrosion of the substrate by the environment (also known as cathodic protection). Thus, the zinc-free shop primers with excellent corrosion protection available on the market today are very limited. Without wishing to be bound by any theory, it is speculated that the epoxy-based shop primer of the present invention d