Container coating system
A multi-coat coating system having an undercoat composition and an overcoat composition, wherein the undercoat, overcoat or both the undercoat and overcoat contain a polymer having segments of a specified formula and are substantially free of polyhydric phenols having estrogenic activity greater than or equal to that of bisphenol S. The coating system is suitable for use on a food-contact surface of food or beverage containers.
1. A multi-coat coating system comprising an undercoat composition and an overcoat composition, wherein the undercoat comprises a polymer having at least two aryl or heteroaryl groups in which each aryl or heteroaryl group includes a ring, an oxygen atom attached to the ring and a substituent group attached to the ring at an ortho or meta position relative to the oxygen atom;
wherein the overcoat comprises:
at least one thermoplastic material; or
a polyester polymer; and
wherein the coating system is substantially free of diphenols having estrogenic activity greater than or equal to that of bisphenol S,
wherein the undercoat polymer has one or more segments of the below Formula I:
wherein:
i. H denotes a hydrogen atom, if present;
ii. each R 1 is independently an atom or group having an atomic weight of at least 15 Daltons;
iii. v is independently 0 to 4; with the proviso that if v is 0, then R 2 is in an ortho or meta position relative to at least one of the oxygen atoms;
iv. w is 3 or 4;
v. R 2 is a multivalent group;
vi. n is 1;
vii. t is 1; and
viii. two or more R 1 or R 2 groups can join to form one or more cyclic groups, and
wherein the undercoat polymer is derived from polyhydric phenols having a logarithmic Relative Proliferative Effect (RPE) of −2 or less.
2. A coating system according to claim 1 , wherein one or more R 1 or R 2 groups are attached to at least one of the phenylene rings depicted in Formula I at an ortho position relative to the oxygen atom.
3. A coating system according to claim 1 , wherein the polymer further includes two or more aryl or heteroaryl groups joined by a polar linking group or a linking group having a molecular weight of at least 125 Daltons.
4. A coating system according to claim 1 , wherein each of the phenylene groups depicted in Formula I includes at least one R 1 group attached to the phenylene ring at an ortho position relative to the oxygen atom.
5. A coating system according to claim 1 , wherein each of the phenylene groups depicted in Formula I includes an R 1 group attached to the phenylene ring at both ortho positions relative to the oxygen atom.
6. A coating system according to claim 1 , wherein the R 1 groups independently comprise methyl or ethyl groups attached to the phenylene ring at an ortho position relative to the oxygen atom.
7. A coating system according to claim 1 , wherein an R 1 group is attached to the phenylene ring at an ortho position relative to the oxygen atom, and a width measured perpendicular from a centerline of the phenylene ring to the maximal outside extent of the van der Waals volume of R 1 is greater than 4.5 Angstroms.
8. A coating system according to claim 1 , wherein v is 1 to 4 and R 2 is —CH 2 —.
9. A coating system according to claim 1 ,
wherein the segments of Formula I are derived from one or more of the diglycidyl ether of 4,4′-methylenebis(2,6-di-t-butylphenol), the diglycidyl ether of 2,2′-methylenebis(4-methyl-6-t-butylphenol), the diglycidyl ether of 4,4′-methylenebis(2,6-dimethylphenol), the diglycidyl ether of 4,4′-butylidenebis(2-t-butyl-5-methylphenol), the diglycidyl ether of bis-(3,5-dimethyl-4-hydroxyphenyl)-methane, or a derivative or combination thereof.
10. A coating system according to claim 1 , wherein the overcoat comprises a thermoplastic material.
11. A coating system according to claim 10 , wherein the thermoplastic material comprises polyvinyl chloride.
12. A coating system according to claim 10 , wherein the thermoplastic material is dispersed in a liquid carrier.
13. A coating system according to claim 10 , wherein the liquid carrier is non-aqueous.
14. A coating system according to claim 10 , wherein the thermoplastic material comprises an organosol or plastisol.
15. A coating system according to claim 10 , wherein the thermoplastic material comprises a vinyl organosol.
16. A coating system according to claim 1 , wherein the polymer of the undercoat composition is a polyether polymer that contains a plurality of aromatic ether segments.
17. A coating system according to claim 16 , wherein the polyether polymer is formed from reactants including a polyhydric phenol and a polyepoxide.
18. A coating system according to claim 1 , wherein the polymer is derived from polyhydric phenols having a logarithmic Relative Proliferative Effect (RPE) of −3 or less.
19. An article, comprising a container, or a portion thereof, comprising a metal substrate and a multi-coat coating system applied on at least a portion of the metal substrate comprising an undercoat composition and an overcoat composition, wherein the undercoat comprises a polymer having at least two aryl or heteroaryl groups in which each aryl or heteroaryl group includes a ring, an oxygen atom attached to the ring and a substituent group attached to the ring at an ortho or meta position relative to the oxygen atom;
wherein the overcoat comprises:
at least one thermoplastic material; or
a polyester polymer; and
wherein the coating system is substantially free of diphenols having estrogenic activity greater than or equal to that of bisphenol S,
wherein the undercoat polymer has one or more segments of the below Formula I:
wherein:
i. H denotes a hydrogen atom, if present;
ii. each R 1 is independently an atom or group having an atomic weight of at least 15 Daltons;
iii. v is independently 0 to 4; with the proviso that if v is 0, then R 2 is in an ortho or meta position relative to at least one of the oxygen atoms;
iv. w is 3 or 4;
v. R 2 is a multivalent group;
vi. n is 1;
vii. t is 1; and
viii. two or more R 1 or R 2 groups can join to form one or more cyclic groups, and
wherein the undercoat polymer is derived from polyhydric phenols having a logarithmic Relative Proliferative Effect (RPE) of −2 or less.
20. A method comprising:
applying an undercoat composition on at least a portion of a metal substrate prior to or after forming the metal substrate into a container,
drying or at least partially curing the undercoat composition, and
applying and curing an overcoat composition to produce a cured multi-coat coating adhered to the metal substrate,
wherein the undercoat comprises a polymer having at least two aryl or heteroaryl groups in which each aryl or heteroaryl group includes a ring, an oxygen atom attached to the ring and a substituent group attached to the ring at an ortho or meta position relative to the oxygen atom;
wherein the overcoat comprises:
at least one thermoplastic material; or
a polyester polymer; and
wherein the coating system is substantially free of diphenols having estrogenic activity greater than or equal to that of bisphenol S,
wherein the undercoat polymer has one or more segments of the below Formula I:
wherein:
i. H denotes a hydrogen atom, if present;
ii. each R 1 is independently an atom or group having an atomic weight of at least 15 Daltons;
iii. v is independently 0 to 4; with the proviso that if v is 0, then R 2 is in an ortho or meta position relative to at least one of the oxygen atoms;
iv. w is 3 or 4;
v. R 2 is a multivalent group;
vi. n is 1;
vii. t is 1; and
viii. two or more R 1 or R 2 groups can join to form one or more cyclic groups, and
wherein the undercoat polymer is derived from polyhydric phenols having a logarithmic Relative Proliferative Effect (RPE) of −2 or less.