Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-07-13
2001-05-01
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S071000, C522S073000, C522S075000, C522S077000, C522S078000, C522S079000, C522S081000, C522S083000, C522S084000, C522S085000, C522S086000, C523S160000, C106S031600, C106S031610, C106S031630
Reexamination Certificate
active
06225369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to an adhesive transfer ink which is used in patterning a mold or a substrate and, more particularly, to a UV-curable, adhesive transfer ink which can be cured by UV, to serve as a mask during the etching of a molds or substrate to be embossed.
2. Description of the Prior Art
Etching is a technique for forming patterns or figures on molds or substrates, which is conventionally conducted as a single etching or multiple etching process. Typically, single etching comprises the steps of (a) pre-treating a substrate with diluted hydrochloric acid, (b) photoresist-coating, (c) photo-masking, (d) UV-irradiating, (e) developing, (f) pattern correction, (g) etching, (h) photoresist-removal and (i) surface treatment. The multiple etching process, developed to accomplish various patterns or figures on a substrate, is carried out by repeating steps (b) through (h) of the single etching process.
In the photoresist-coating step of the single or multiple etching process, photoresist is spray-coated or screen-coated on a substrate to which figures are transferred. Usually, it is difficult to uniformly coat photoresist. In the multiple etching process, an etched primary figure or pattern is coated with photoresist and the resultant is coated with a secondary figure or pattern-bearing film. At this time, however, the primary figure or pattern is not seen or exposed by the photoresist.
Also, conventional etching techniques suffer from a disadvantage in that UV is not uniformly irradiated on the surfaces of substrates or molds owing to their outward forms, so that developing defectives take place in a subsequent developing step, making it difficult to precisely form predetermined patterns or figures. When a developing defective occurs, it is necessary to correct the pattern, resulting in an increase in the number of the process steps.
In order to overcome such disadvantages, there has been introduced a water-transfer process in which, after a printing sheet bearing a predetermined pattern or figure is coated on a substrate, application of water allows the predetermined pattern or figure to transfer to the substrate. Then, the sheet is separated from the substrate and the pattern or figure remain alone. However, it is also difficult to obtain a desired pattern or figure because the printing sheet is overly sensitive to moisture.
SUMMARY OF THE INVENTION
The intensive and thorough research on the transfer of figures or patterns to substrates, performed by the present inventors, resulted in the finding that a precise and definite pattern can be embossed on a mold or a substrate by the use of a material which can be cured by UV is resistant to an etchant.
Therefore, it is an object of the present invention to overcome the above problems encountered in the prior art and to provide a UV-curable, adhesive transfer ink with the aid of which a pattern or patterns can be precisely and definitely embossed on a mold or a substrate.
It is another object of the present invention to provide a printing sheet on which a predetermined pattern is printed with the above UV-curable, adhesive transfer ink.
In accordance with one aspect of the present invention, there is provided a UV-curable transfer ink, which comprises 20-40% by weight of a UV-reactive ink, 20-40% by weight of an acrylic (co) polymer, 4-6% by weight of an ethylene vinyl acetate copolymer, 25-35% by weight of an organic solvent and 0.5-5% by weight of a bulking agent.
In accordance with another object of the present invention, there is provided a printing sheet, which comprises a polyethylene or polypropylene film which is screen-printed in a predetermined pattern with the transfer ink, and a silicon-coated, releasable polyethylene terephthalate backing laminated on the film.
DETAILED DESCRIPTION OF THE INVENTION
The present invention pertains to an adhesive transfer ink which allows figures or patterns to be transferred through a UV-curable mechanism. The adhesive transfer ink comprises a UV-reactive ink, an acrylic (co) polymer, an ethylene vinyl acetate (EVA) copolymer, a bulking agent, and an organic solvent.
The UV-reactive ink amounts to 20-40% by weight of the total weight of the adhesive transfer ink, and preferably to 25-35% by weight. For example, if the UV-reactive ink is used at an amount less than 20% by weight, deterioration is generated at the time of UV-curing, resulting in a poor transferred state. On the other hand, if the UV-reactive ink is over 40% by weight, the substrate is stained with the resulting adhesive transfer ink printed on a printing film.
The UV-reactive ink comprises 15-25% by weight of pigment, 3-4% by weight of polyethylene wax, 1.5-2.0% by weight of a bulking agent, 12-16% by weight of a curing agent, 15-25% by weight of polyester acrylate, 10-12% by weight of an acrylic monomer, 25-36% by weight of aliphatic urethane diacrylate, and 1.5-2.0% by weight of trimethylol propane triacrylate. Preferable is that commercially available from Dongyang Print Co., Korea, identified as Model “Hi-Cure”.
For the pigment, there is exemplified cyanium blue (Songwon Color Co., Korea), toluidine red (Songwon Color Co., Korea) or carbon black.
Illustrative, but non-limitative examples of the bulking agent contained in the UV-reactive ink include aluminum oxide, silicon dioxide, mica, kaolin, talc, barium sulfate, potassium sulfate, alumina and silica.
Useful as the curing agent is dicycan diamide.
Concrete examples of the acrylic monomer contained in the UV-reactive ink include glycerolpropoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritol pentaacrylate, bisphenol-A type dimethacrylate, polyethyleneglycol diacrylate, polypropyleneglycol diacrylate, diethyleneglycol diacrylate, triethyleneglycol diacrylate, and tripropyleneglycol diacaylate.
Functioning to provide an adhesive property to the transfer ink, the acrylic (co) polymer, exemplified by, for example, polyacrylic acid, acrylonitirile butadienestyrene, styreneacrylonitrile, acrylonitrile butadiene and natural rubber, preferably ranges, in quantity, from 20 to 40% by weight based on the total weight of the transfer ink. For instance, if the acrylic (co) polymer is used at an amount less than 20% by weight, the resulting ink transfer is poor in adhesiveness, leading to a deterioration in the transferred pattern or figure. On the other hand, when the acrylic (co) polymer is present at an amount greater than 40% by weight, the transferred ink is so viscous that, in screen printing, the mesh of the screen may become clogged.
In order to prevent the transfer ink from sagging while maintaining the adhesive property of the acrylic (co) polymer, ethylene vinyl acetate is used in the present invention. The ethylene vinyl acetate is also useful to increase the ink tenacity and chemical resistance after the transfer ink is printed on a printing film. Amounting to 4-8% by weight based on the weight of the transfer ink, the ethylene vinyl acetate may be exemplified by modified ethylene vinyl acetate and carbonic acid vinyl compounds.
The organic solvent has a function of preventing the ink from unintentionally staining portions of the target, by providing a coating to the printed ink on the printing film through solvent evaporation. Examples of the organic solvent include toluene, cyclohexane, methyl salicylate, butyl acetate, ethyl acetate, amyl acetate, isopropyl alcohol, methyl isobutyl ketone, methyl ethyl ketone, dibutyl phthalate, xylene and benzene, with preference to toluene. The organic solvent is preferably 25-35% by weight based on the total weight of the transfer ink. For example, when the organic solvent is below 25% by weight, the mesh of the screen is clogged, so screen printing cannot be conducted continuously. In addition, the ink gels too fast. On the other hand, if the organic solvent is greater than 35% by weight, the transfer ink runs after printing.
Being identical to that for the UV-reactive ink, the bulking agent for the transfer ink is in the range of 0.5 t
Jacobson Price Holman & Stern PLLC
McClendon Sanza
Moltex Co., Ltd.
Seidleck James J.
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