Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-08-17
2003-05-13
Lorengo, J. A. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S230000, C156S233000, C156S240000, C156S241000, C156S247000, C156S273300, C156S275500, C156S277000, C156S326000, C427S146000, C427S147000, C427S148000, C427S487000, C427S511000, C428S195100, C428S204000, C428S210000, C428S914000
Reexamination Certificate
active
06562172
ABSTRACT:
TECHNICAL FIELD
The invention is in the field of decorating glass with ultraviolet (UV) radiation curable compositions.
BACKGROUND OF THE INVENTION
Hot stamping is the heat transfer of a pigmented color or metallized surface from a polyester carrier onto a thermoplastic substrate. A heated die or roller is used to apply pressure to the hot stamping foil. The pressure forces the pigmented or metallized portion of foil into contact with the plastic substrate. The combination of heat and pressure softens the plastic substrate and activates the foil, causing it to adhere to the substrate. A vertical stamping or roll-on machine is used for the operation. The vertical stamping machine contains a heated die of brass, steel, or silicone rubber to transfer an area of a specific pattern as each part is placed into position. Roll-on methods utilize a silicone rubber roller or arced die to apply the foil in a continuous or batch process. Heat transfer can be achieved at temperatures of about 107° C.
Hot stamping is an efficient, inexpensive way to apply decoration to a thermoplastic substrate. Hot stamping cannot be used with glass because glass melts at a much higher temperature than most thermoplastic materials.
Generally decoration in the form of gold or silver leaf, color design, or printing, is applied to glass by a glazing process similar to that used with ceramics. The colored or metallic ink decoration is applied to the glass container by a variety of methods such as silk screen, printing, etc. The container is then subjected to extremely high kiln temperatures and the decoration is, in essence, baked on. Unfortunately this process is time consuming, expensive, energy intensive, and subject to safety considerations due to the high temperatures and gases necessary to operate the kilns.
Applying hot stamping foil to glass is disclosing in U.S. Pat. No. 5,708,047, which is hereby incorporated by reference. The glass is first printed with a radiation curable cycloaliphatic epoxide ink, and cured by exposure to radiation. Hot stamping foil is applied, and adheres to the cured ink design. However, the adhesion and durability of such decorated containers can always be improved. Accordingly, there is a need for ink compositions that provide improved adhesion and durability in the decoration of glass and other vitreous substrates.
SUMMARY OF THE INVENTION
The invention comprises a method for decorating a vitreous substrate with a radiation curable ink composition, comprising the steps of:
a) applying an ink composition comprised of an N-vinyl lactam to the glass in a predetermined design, said ink being operable when cured to bond to the vitreous substrate,
b) curing the ink on the vitreous substrate by exposing it to the radiation by which it is curable, thereby bonding the ink composition to the substrate,
The invention additionally comprises a method for decorating a vitreous substrate with hot stamping foil comprising the steps of:
a) applying an ink composition comprised of an N-vinyl lactam to the glass in a predetermined design, said ink being operable when cured to bond to the vitreous substrate,
b) curing the ink on the vitreous substrate by exposing it to the radiation by which it is curable, thereby bonding the ink composition to the substrate,
c) pressing a sheet of hot stamping foil against the substrate with a die heated to a temperature sufficient to cause a portion of the hot stamping foil to adhere to the heated, cured, ink design but not to the ink free areas of the vitreous substrate,
d) removing the die, thereby leaving behind a portion of the foil adhered to the ink design.
DETAILED DESCRIPTION
All percentages mentioned herein are percentages by weight, unless otherwise indicated.
INK COMPOSITIONS USED IN THE METHOD
N-Vinyl Lactam
The ink compositions used in the method of the invention contain 10-60%, preferably 15-55%, more preferably 20-50% of an N-vinyl lactam. Preferably the N-vinyl lactam comprises a lactam having 4 to 6 ring carbon atoms. The N-vinyl lactam may be a liquid or solid at room temperature, and is a monomer, oligomer, or low molecular weight homo- or copolymer. Preferably the N-vinyl lactam has a molecular weight of about 100 to 150 daltons. Preferred N-vinyl lactams for use in the method of the invention are N-vinyl pyrrolidone and N-vinyl caprolactam. N-vinyl pyrrolidone may be purchased from International Specialty Products, Wayne N.J., and has the CAS Registry No. 86-12-0. This monomer has a molecular weight of 111 daltons, is a liquid at room temperature, and has a melting point of 17° C. N-vinyl caprolactam may also be purchased from International Specialty Products, and has the CAS Registry No. 2235-00-9. This monomer has a molecular weight of 139 daltons, and is a solid at room temperature, having a melting point of 35° C. In the preferred embodiment of the invention, the ink composition contains N-vinyl caprolactam.
Other Ethylenically Unsaturated Monomers or Oligomers
Preferably, the ink compositions also contain other ingredients such as one or more ethylenically unsaturated monomers or oligomers in addition to the N-vinyl lactam. A variety of other ethylenically unsaturated monomers or oligomers may be used, including those which cure by both free radical and cationic mechanisms.
Preferably the ink compositions contains 15-65%, preferably 20-60%, more preferably 25-50% by weight of the total composition of at least one ethylenically unsaturated monomer, oligomer, or low molecular weight homo- or copolymer in addition to the N-vinyl lactam. Suitable monomers may contain free acid groups, such as a carboxylic acid, sulfonic acid, or phosphoric acid group. The phrase “having a free acid group” means that the monomer unit has at least one free acid group, or the oligomer contains at least one monomer unit containing a free acid group, or if a homo- or copolymer, at least one monomer unit thereof contains at least one free acid group. Preferably the ink composition contains a monomer or oligomer, in particular an ethylenically unsaturated monomer or oligomer having at least one free acid group. Examples of preferred monomers or oligomers include those having carboxylic acid functional groups such as:
wherein R
1
is H, a C
1-30
straight or branched chain, substituted or unsubstituted, saturated or unsaturated alkyl, aryl, aralkyl, a pyrrolidone, or a substituted or unsubstituted aromatic, alicyclic, or bicyclic ring where the substitutents are C
1-30
straight or branched chain alkyl, or halogen.
Also suitable are ethylenically unsaturated monomers or oligomers having the unit formula:
wherein R
1
is as defined above, and R
2
is C
1-30
straight or branched chain, substituted or unsubstituted, saturated or unsaturated alkyl, aryl, aralkyl, a pyrrolidone, or a substituted or unsubstituted aromatic, alicyclic, or bicyclic ring where the substitutents are C
1-30
straight or branched chain alkyl, or halogen; or 2-tetrahydrofuran; or X—COOH wherein X is a C
1-30
straight or branched chain alkyl, aryl, arylalkyl, or (CH
2
CH
2
—O)
n
Y COOH or (CH
2
CH
2
CH
2
—O)
n
Y COOH wherein Y is a C
1-10
straight or branched chain alkyl and n is 1-10,000.
Preferably the monomer or oligomer is of Formula II wherein R
1
is H or CH
3
, and R
2
is is 2-tetrahydro-furan, or X—COOH wherein X is a C
1-10
straight or branched chain alkyl, more preferably ethyl. More preferably the composition comprises a mixture of Formula II monomers or oligomers, the first being wherein R
2
is 2-tetrahydrofuran, and the monomer or oligomer is tetrahydrofurfuryl acrylate, which preferably has a molecular weight of about 156 daltons and is a clear liquid having a specific gravity of about 0.872. This tetrahydrofurfuryl acrylate is sold by Sartomer Company under the tradename SR 285. The second preferred Formula II monomer or oligomer is wherein R
2
is also beta-carboxyethyl, e.g. as in beta-carboxyethyl acrylate, which is sold under the tradename B-CEA by UCB Radcure, Inc. B-CEA is a reactive monomer which contains both acrylate and carboxylic acid functionality, predomin
Hu Ming
Kamen Melvin Edwin
Deco Patents, Inc.
Lorengo J. A.
Pennie & Edmonds LLP
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