Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-01-30
2003-08-19
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S075000, C522S081000, C522S083000, C522S084000, C522S085000, C106S035000, C427S466000, C347S001000
Reexamination Certificate
active
06608119
ABSTRACT:
FIELD OF INVENTION
The present invention relates to water-base ink, a method of manufacturing the ink and a printing method using the ink, and in particular, to ink that is ideal for inkjet printing on a print surface where water-base solvent does not permeate, such as on a printed substrate.
DESCRIPTION OF RELATED ART
Ink jet printing is a printing method in which small drops of ink are ejected out of a nozzle to attach to a printing surface of a print medium, such as paper or other medium, and then solvent is dried from the attached ink (the attached ink from which the solvent is dried is hereafter referred to as the ink attachment) and the colorant is fixed on the printed surface. This method enables high-speed printing of high-resolution and high quality images. In general, ink used in ink jet printing has a water-base solvent as the main component, to which colorant and a penetrant such as glycerin (additives used to prevent clotting) are added.
However, if the printing surface is made of a surface which makes the permeation of a water-base solvent extremely difficult or even impossible, for example, board or film surfaces made of regular paper, cloth, metal, phenol, melamine, vinyl chloride, acrylic or plastic such as polycarbonate, execution of ink jet printing using the aforementioned ink designed for normal ink jet printing becomes difficult.
For this reason, in this type of usage, it becomes necessary to have the ink contain an ingredient which enables stable fixing of colorant (an ingredient which remains as a film on the printing surface after being dried).
Moreover, when printing is performed on printed substrates and the like, the ink must dry quickly, and the ink film must have a high level of chemical proof properties, and the ink film must be very hard.
As an example of ink with the aforementioned qualities, Japanese Laid Open Patent Publication 3-216379 discloses an ink jet ink that contains a colorant and an ingredient which becomes polymerized upon radiation of ultra-violet rays (polymerizing monomer, oligomer, or photoinitiator).
Moreover, U.S. Pat. No. 5,623,001 discloses ink jet ink that contains water, and polymerization material (oligomer or mixture of oligomer and monomer) which admixes with water and hardens with ultra-violet rays, photoinitiator and colorant.
Furthermore, Japan Laid Open Patent Publication 3-220218 discloses a screen printing ink component that hardens with ultra-violet rays and which contains polyurethane (meth) acrylate resin, N-vinyl pyrrolidone, acryloyl morpholine, photoinitiator and pigment.
In the ink described in these publications, photoinitiators in the ink attachment are activated by irradiation of ultra-violet rays after the ink is attached on the printing surface, and a polymerizing oligomer and/or a monomer's polymerizing reaction is generated, which polymerization fixes colorant in the ink attachment on the printing surface. Hence, it is expected that the ink attachment will dry in a short time and a hard ink film with a high level of chemical proofness will be obtained with a high color concentration and uniform printing without smearing and unevenness.
However, the ink described in these publications needs to be enhanced in terms of stability and ink film strength.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a photo polymerization type water-base ink having an extremely high level of printing stability and ink film strength after light irradiation when used in ink jet printing, such as providing ink with an enhanced capability for ink jet printing onto a printed substrate.
In order to achieve the aforementioned object, the present invention provides photo polymerization water-base ink including colorant, photo polymerization resin, photoinitiator, and water-base solvent. The photo polymerization resin includes oligomer particles in the emulsion state and a monomer residing in the oligomer particles. The polar solvent includes one or more of 2-pyrrolidone, N-acryloyl morpholine and N-vinyl-2-pyrrolidone with weight ratio of between 0.1 to 10 is also contained.
In this ink, because photo polymerizing ink includes oligomer particles in the emulsion state and monomer residing in the oligomer particles, the photo polymerization resin is dispersed uniformly in the ink and is maintained in this condition for a long time. Moreover, because the polar solvent includes one or more of 2-pyrrolidone, N-acryloyl morpholine and N-vinyl-2-pyrrolidone with a weight ratio of between 0.1% to 10%, an extremely high level of printing stability is obtained when used in ink jet printing.
In the water-base ink of the present invention, the polar solvent preferably contains 2-pyrrolidone and N-acryloyl morpholine.
By so doing, water-base ink of the present invention assures an extremely high level of printing stability and ink film strength after light irradiation when used in ink jet printing.
Moreover, the present invention provides photo polymerization water-base ink, including: colorant, photo polymerization resin, photoinitiator, and water-base solvent that includes polar solvent having a reactive group (vinyl radical, acryl radical, metacryl radical and others) reacting with photo polymerization resin.
The ratio of the polar solvent in the ink, for example, a weight ratio of between 0.1% to 10%, preferably between 1% to 7%.
This ink exhibits a high level of storage stability with an extremely high level of printing stability, strong ink film and superior chemical proof property when used in ink jet printing. As indicated in 1 and 2 below, these advantages may be provided due to a polar solvent containing a reaction radical which reacts with photo polymerization resin.
1. Because polarity of the solvent is large compared to that of a normal surfactant used to secure printing stability, the dissolution power of the solvent with respect to water is large. Therefore, the solvent does not distort the dispersion properties between the colorant and the photo polymerization resin and enables stable dissolution or dispersion of the ingredients which make up the other ink components. This solvent, because it has a polymerizing reaction radical in its molecular structure, achieves high bridge density in the film.
2. N-acryloyl morpholine and N-vinyl-2-pyrrolidone are typical examples of the solvent.
In the water-base ink, the photo polymerization resin preferably includes oligomer particles in an emulsion state and monomers residing in the oligomer particles.
Polyesteracrylate, polyurethaneacrylate, epoxyacrylate, polyetheracrylate, oligoacrylate, alkidacrylate and polyoleacrylate are some of the examples that can be used as oligomer in the present invention. Of these, it is preferable to use polyesteracrylate or polyurethaneacrylate.
In the present invention, molecular weight of the oligomer to be used is in the 500-20,000 range, preferably in the 500-10,000 range.
In the ink of the present invention, the oligomer content in terms of the percentage weight is in the 1% to 50% range, and preferably in the 3%-30% range.
Monofunctional acrylate and methacrylate, multifunctional acrylate and metaacrylate are examples of monomers that can be used in the present invention. These monomers having low molecular polyole acrylate and methacrylate have the merit of low viscosity and speedy hardening properties. The following are typical monomers which may be used in the present invention: diethyleneglycol diacrylate, neopentylglycol diacrylate, 1,6 hexanedioldiacrylate, hydroxypropyl ester-neopentyl-glycoldiacrylate, trimethylol-propane-triacrylate, pentaerythritol-triacrylate, dipenthacrythritol-hexaacrylate, acryloyl-morpholine, 2-phenoxy-ethylacrylate, phthalic acid-hydrogen-(2,2,2-triacrylonitrille-oxymethyl)ethyl, dipentaetythritol-polyacrate, dipentaerythritol-polyacryrate, and others.
Of these listed above, acryloyl morpholine, 2-phenoxyethylacrylate, phthalic acid hydroen-(2,2,2,-triacrylonitrille oxymethyl0ethyl, dipenthaerythritol-polyacrylate, dipentaerithrytol-polyacrylate are preferred monomers.
In the presen
Takemoto Kiyohiko
Tanabe Seiichi
Taniguchi Makoto
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