Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
1999-06-08
2001-11-27
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C522S066000, C522S077000, C522S067000, C522S168000, C522S170000, C524S731000, C428S410000, C428S447000, C427S386000, C427S387000, C427S487000, C427S515000
Reexamination Certificate
active
06322892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cation-polymerizable coating composition capable of forming a coating film having excellent surface lubricity and its durability.
2. Description of the Prior Art
As a cation-polymerizable paint used to form a coating film for metal cans or metal cans coated with plastic film, paints containing an epoxy resin and a cation-polymerization initiator are known until now.
The curing of the coating film on the abovementioned metal cans or metal cans coated with plastic film after coating is conducted by baking for a short time or ultraviolet irradiation, on a high speed production line. Metal cans are transported to the next procedures such as inner surface coating step or processing step after the coating and curing. As the coating film is prone to be damaged during the transport, a silicon compound is usually mixed in the paint in order to give lubricity to the surface of the coating film. However, when a silicon compound is mixed in the paint, there tends to occur problems such as cissing at the coating film, whitening of the coating or deteriorated smoothness of the coating film.
In Japanese Laid-open Publication No.291132/1997 there is disclosed an ultraviolet-curing resin composition for metal can containing an epoxy compound, a modified dimethylpolysiloxane having as a side chain a polyoxyalkylene chain containing a hydroxyl group(s), a methoxy group (s) or a methylcarbonyloxy group(s) at the end, and a photocation-polymerization initiator. This publication describes that a coating film with excellent adhesivity, lubricity, retort resistance, coating film hardness, processibility, surface smoothness and transparency can be obtained by coating the composition on a metal can or a deep-drawn metal can coated with polyester film. However, a coating film obtained with the composition has a problem that the lubricity of the coating film after retort treatment is not sufficient.
The main purpose of the present invention is to provide a short time curing type cation-polymerizable coating composition capable of forming a coating film with excellent adhesivity to substrate, lubricity, retort resistance, coating film hardness, processibility, surface smoothness and transparency and, in addition, with excellent lubricity of the coating film after retort treatment.
Another purpose of the present invention is to provide a method of coating metal cans or metal cans coated with plastic film by using the above-mentioned coating composition.
A further purpose of the present invention is to provide an article such as a metal can or a metal can coated with plastic film, coated by using the above-mentioned coating composition.
Other purposes and features of the present invention will be clarified in the following description.
SUMMARY OF THE INVENTION
The present invention provides a cation-polymerizable coating composition characterized by containing
(A) a cation-polymerizable binder component consisting of (a) an epoxy group-containing compound and, as necessary, (b) an oxetane compound,
(B) a modified dimethylsilicone oil with a number average molecular weight of 500-1,000,000 having a hydroxyl group(s) bonded directly to a silicon atom, a hydrolyzable functional group(s) bonded directly to a silicon atom and capable of forming a hydroxyl group(s) bonded directly to a silicon atom by hydrolysis, or a carboxyl group(s), and
(C) a cation-polymerization initiator which forms a cation by irradiation or by heating.
DETAILED DESCRIPTION OF THE INVENTION
The cation-polymerizable coating composition of the present invention is a coating composition curable by cationic polymerization by irradiation of ultraviolet rays etc. or by heating. The coating composition of the present invention is described more specifically as follows.
Cation-polymerizable Binder Component (A):
The cation-polymerizable binder component (A) constituting the coating composition of the present invention is a binder component which can be cured by cationic polymerization by irradiation of ultraviolet rays etc. or by heating and consists of an epoxy group-containing compound (a) and, as necessary, an oxetane compound (b).
As an epoxy group-containing compound (a), any compound containing more than one, preferably 1-4 epoxy groups per molecule can be used without special restriction and compounds containing an alicyclic epoxy group(s) having cyclohexene oxide or cyclopentene oxide structure in the molecule (a-1) and glycidyl group-containing compounds (a-2) can be preferably used.
As specific examples of the above-mentioned compounds containing an alicyclic epoxy group(s) (a-1) there can be mentioned, for example, dicyclopentadiene dioxide, limonene dioxide, (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexanecarboxylate, 3-vinylcyclohexene oxide, bis(2,3-epoxycyclopentyl) ether, bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, (3,4-epoxycyclohexyl)methyl alcohol, (3,4-epoxy-6-methylcyclohexyl)methyl 3,4-epoxy-6-methylcyclohexanecarboxylate, ethylene glycol bis(3,4-epoxycyclohexyl) ether, 3,4-epoxycyclohexenecarboxylic acid ethylene glycol diester, (3,4-epoxycyclohexyl)-ethyltrimethoxysilane,
(wherein h is an integer of more than 1, particularly in the range of 1-5.)
(wherein a and b each is an integer of more than 0, particularly in the range of 0-5.)
(wherein j, k, m and n each is an integer of more than 0, particularly in the range of 0-5.)
(co)polymers containing an alicyclic epoxy group(s) obtained by (co)polymerizing an ethylenic unsaturated monomer containing an al icycIc epoxy group(s) such as 3,4-epoxycyclohexylmethyl (meth)acrylate singly or with another polymerizable unsaturated monomer(s).
As specific examples of the aforementioned glycidyl group-containing compounds (a-2) there can be mentioned ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, diglycerol tetraglycidyl ether, trimethylolpropane triglycidyl ether, spiroglycol diglycidyl ether, 2,6-diglycidyl phenyl ether, sorbitol polyglycidyl ether, triglycidyl isocyanurate, bisphenol A diglycidyl ether, butadiene dioxide, diglycidyl phthalate, 3-ethyl-3-glycidyloxetane, epoxidized polybutadiene, novolac type epoxy resin, epoxylated xylylenic resin; copolymers cntaining a glycidyl group(s) obtained by (co)polymerizing a glycidyl group-containing ethylenic unsaturated monomer such as glycidyl (meth)acrylate singly or another polymerizable unsaturated monomer(s).
As other polymerizable unsaturated monomers used for the preparation of the aforementioned copolymers containing an alicyclic epoxy group(s) or the above-mentioned copolymers containing a glycidyl group(s) there can be mentioned, for example, C
1-24
alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate etc.; epoxy group-containing polymerizable unsaturated monomers such as glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, allyl glycidyl ether, vinyl glycidyl ether etc.; monoester compounds of polyhydric alcohols with acrylic acid or methacrylic acid such as 2-hydroxyethyl (meth)acrylate, hyddroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate etc.; hydroxyl group-containing monomers such as compounds obtained by ring-opening polymerization of &egr;-caprolactone to the above-mentioned monoester compounds of polyhydric alcohols with acrylic acid or methacrylic acid; carboxyl group-containing polymerizable unsaturated monomers such as acrylic acid, methacrylic acid, maleic acid,
Dawson Robert
Kansai Paint Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
Zimmer Marc S.
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