Phenolic resin and coating compositions using the same
Coating compositions comprising a phenolic resin and a film-forming resin having functional groups that are reactive with the functionality of the phenolic resin are disclosed herein. The phenolic resin comprises a phenol group containing compound and a glyoxylic acid containing compound. Such phenolic resins may be used as formaldehyde-free crosslinkers in coating compositions and such coating compositions may be used on substrates comprising a non-porous material, such as metal, glass, and/or plastic. Also disclosed are methods of coating a substrate and coated substrates, including food and/or beverage containers.
1 . A coating composition for a substrate comprising:
a film-forming resin having a number average molecular weight (Mn) of at least 1000, wherein the film-forming resin comprises a core/shell acrylic latex material, or a polyester graft acrylic resin, or a combination thereof; and
a phenolic resin comprising a reaction product of a reaction mixture comprising:
a phenol group containing compound; and
a glyoxylic acid containing compound; and
wherein the film-forming resin has functional groups which are reactive with the functionality of the phenolic resin, wherein the coating composition comprises greater than 50% of the film-forming resin, based on the weight of the film-forming resin and the phenolic resin, and wherein the coating composition is substantially free of formaldehyde.
2 . The coating composition of claim 1 , wherein the composition is thermally curable.
3 . The coating composition of claim 1 , wherein the phenolic resin is self-crosslinkable.
4 . The coating composition of claim 1 , wherein the reaction mixture further comprises a monoaldehyde or a ketone.
5 . The coating composition of claim 1 , wherein the film-forming resin comprises a core/shell acrylic latex material.
6 . The coating composition of claim 1 , wherein the film-forming resin comprises a polyester graft acrylic resin.
7 . The coating composition of claim 1 , wherein the film-forming resin is present in an amount of up to 99.5 wt %, based on the total weight of the film-forming resin and the phenolic resin.
8 . The coating composition of claim 1 , wherein the phenolic resin is present in an amount of at least 0.5 wt %, based on the total weight of the film-forming resin and the phenolic resin.
9 . The coating composition of claim 1 , wherein the glyoxylic acid containing compound comprises glyoxylic acid, acetals, hemiacetals, esters, and/or salts thereof.
10 . The coating composition of claim 1 , wherein the phenol group containing compound comprises resorcinol and/or hydroquinone.
11 . The coating composition of claim 1 , wherein the phenol group containing compound comprises at least two hydroxyl groups.
12 . The coating composition of claim 1 , wherein the molar ratio of the glyoxylic acid containing compound to the phenol group containing compound is 1:1 to 3:1.
13 . The coating composition of claim 1 , wherein the phenolic resin has a pH of 6 to 9.
14 . A coated substrate having a surface at least partially coated with the coating composition of claim 1 .
15 . A food and/or beverage container comprising a metal substrate having a surface at least partially coated with the coating composition of claim 1 .
16 . A monobloc aerosol can and/or tube comprising a metal substrate having a surface at least partially coated with the coating composition of claim 1 .
17 . A coating composition comprising:
50% to 99.5% of a film-forming resin comprising a core/shell acrylic latex material, or a polyester graft acrylic resin, or a combination thereof; and
0.5% to 50% of a phenolic resin;
wherein percentages of the film-forming resin and the phenolic resin are based on the weight of the film-forming resin and the phenolic resin;
wherein the coating composition is substantially free of formaldehyde; and
wherein the phenolic resin comprises a reaction product of a reaction mixture comprising:
a phenol group containing compound comprising at least two hydroxyl groups; and
a glyoxylic acid containing compound.
18 . The coating composition of claim 17 , wherein the reaction mixture further comprises a monoaldehyde or a ketone.
19 . The coating composition of claim 17 , wherein the glyoxylic acid containing compound comprises glyoxylic acid, acetals, hemiacetals, esters, and/or salts thereof; and wherein the phenol group containing compound comprises resorcinol and/or hydroquinone.
20 . The coating composition of claim 17 , wherein the molar ratio of the glyoxylic acid containing compound to the phenol group containing compound is 1:1 to 3:1.
21 . The coating composition of claim 17 , wherein the film-forming resin comprises a core/shell acrylic latex material.