Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-06-08
2004-09-28
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S590000
Reexamination Certificate
active
06797748
ABSTRACT:
FIELD OF INVENTION
The present invention relates to ink compositions for writing instruments, methods of making such ink compositions and writing instruments making use of the ink composition. The non-erasable ink compositions comprise an isocyanate free thermoplastic polyurethane resin, organic solvent(s), and colorant(s). Inks in accordance with the present invention are useful in pens for handwriting
BACKGROUND OF INVENTION
Many attempts have been made to improve the performance of writing inks (reduce seepage, reduce skipping, modify viscosity for better flow and smoothness of writing) by incorporating additives, resins, solvents, waxes, etc. into the ink formulations. To our knowledge, no solvent-based non-erasable writing inks exist in the patent literature which use an isocyanate free thermoplastic polyurethane resin.
U.S. Pat. No. 5,942,027 to Ikai discloses a solvent based writing ink which contains a sub-micron dispersion of silica to achieve non-seepage. Ikai does not disclose the use of an isocyanate free thermoplastic polyurethane resin to achieve a well functioning writing ink. U.S. Pat. No. 5,868,511 to Osada discloses a solvent based ink with good writing characteristics and long cap off time which contains a resin dissolved in solvent with a colorant However, Osada's patent does not disclose the use of an isocyanate free thermoplastic polyurethane resin to achieve a functional writing ink. U.S. Pat. No. 4,525,216 to Nakanishi discloses a non-aqueous erasable ink which contains organic solvent, colorant, resin, an alkylamide, and a sorbitan fatty acid. Nakanishi does not disclose the use of an isocyanate free polyurethane resin to achieve good writing characteristics.
Solvent based writing ink formulations which contain dissolved resins and dissolved or dispersed colorants are known in the art. U.S. Pat. No. 5,980,624 to Ichikawa discloses a writing ink which contains a resin dissolved in a solvent with a colorant but does not disclose the use of an isocyanate free polyurethane resin. U.S. Pat. No. 6,048,914 to Goto discloses a writing ink which contains a resin dissolved in a solvent with a colorant but does not disclose the use of an isocyanate free polyurethane resin U.S. Pat. No. 6,160,035 to Idogawa discloses a writing ink which contains a resin dissolved in a solvent with a colorant but does not disclose the use of an isocyanate free polyurethane resin.
Inks comprising reactive polyurethanes are known in the printing ink art. U.S. Pat. No.5,248,752 to Argyropoulos et al. discloses the use of polyurethane meth(acrylate) polymers which react either thermally or by actinic radiation for use in inks. U.S. Pat. No. 4,003,751 to Carder discloses an ink composition comprising at least cofunctional acrylate-urethane which will react either thermally or by actinic radiation. U.S. Pat. No. 3,728,298 to Hartmann discloses the use of a printing ink based upon a polyurethane resin which is applied in a relatively uncured state, and is permitted to cure in room temperature under the action of curing agents. U.S. Pat. No. 3,728,298 further discloses a pot life of approximately forty hours. None of these references disclose the use of an isocyanate free thermoplastic polyurethane resin in writing inks.
U.S. Pat. No. 4,812,492 to Eckes discloses the use of aqueous pigment dispersions containing a finely divided inorganic and/or organic pigment, an aqueous polyurethane dispersion, water and optionally organic solvent U.S. Pat. No. 4,812,492 does not disclose solvent soluble colorants or the non-aqueous thermoplastic polyurethane resin of the present invention.
U.S. Pat. No. 4,389,499 to Riesgraf discloses an erasable writing ink which contains a resin dissolved in a solvent with a colorant U.S. Pat. No. 4,390,646 to Ferguson discloses an erasable writing ink which contains a thermoplastic block copolymer resin dissolved in a solvent with a colorant U.S. Pat. No. 4,391,927 to Farmer discloses an erasable writing ink which contains a thermoplastic block copolymer resin dissolved in a solvent with a colorant. These references do not disclose the non-erasable ink compositions of the present invention.
U.S. Pat. No. 5,852,072 to Banning et al. discloses an erasable ink composition containing a water-insoluble polymeric dye obtained from the polymerization of at least two coreactive polyfunctional monomers with at least one of the monomers possessing a dye moiety covalently bonded thereto. The ink is intended for marking instrument, particularly ballpoint pens. U.S. Pat. No. 5,852,072 does not disclose the isocyanate free polyurethane resin or the non-erasale ink compositions of the present invention.
Like U.S. Pat. No. 5,852,072, U.S. Pat. No. 5,756,561 to Wang, U.S. Pat. No. 5,900,445 to Chandler and U.S. Pat. No. 5,852,073 to Villiger discloses inks for ballpoint pens using polyurethanes. These references do not disclose the isocyanate free polyurethane resin or the non-erasable ink compositions of the present invention
U.S. Pat. No. 6,040,356 to Kanki discloses a gravure ink made using solvent, pigment and polyurethane resin. U.S. Pat. No. 6,040,356 does not disclose the solvent soluble colorants of the present invention nor is the present invention designed to be a printing ink.
This invention satisfies the need for a well performing writing ink for writing instruments which does not seep or leak from the delivery end of the pen.
SUMMARY OF INVENTION
The present invention discloses an ink for a writing instrument, wherein the ink exhibits better overall performance when compared in the same writing instruments to inks which do not contain the isocyanate free thermoplastic polyurethane resin. Preferably, the writing instrument is usable on ink-absorbing surfaces. Preferably, the writing instrument is a ballpoint pen.
In one embodiment of the invention, a non-erasable ink composition for a writing instrument comprises an isocyanate free thermoplastic polyurethane resin, an organic solvent and a colorant. Preferably, the resin is a solution grade polyurethane thermoplastic resin. More preferably, the polyurethane resin is Estane® 5700 series available from B.F. Goodrich. Preferably, the isocyanate free thermoplastic polyurethane resin is present in the ink composition from about 0.1 to about 75 weight percent of the ink. More preferably, the isocyanate free thermoplastic polyurethane resin is present in the ink composition from about 1.0 to about 35 weight percent of the ink.
Preferably, the weight average molecular weight of the resin is from about 1000 to about 100,000.
Preferably, the thermoplastic polyurethane resin and organic solvent form a homogeneous solution and the colorant is soluble in the homogeneous solution or dispersed in the solution.
The colorant may be used alone or in the form of a mixture of two or more colorants. Preferably, the colorant is present in the ink composition in amounts from about 0.1 to about 60 weight percent of the ink composition. The colorant can be a dye or a pigment. Preferably, the pigment is selected from the group consisting of organic pigments, inorganic pigments, metallic pigments, phosphorescent pigments, fluorescent pigments, photochromic pigments, thermochromic pigments, iridescent pigments, pearlescent pigments and liquid crystal pigments.
The viscosity of the ink compositions of the present invention is that usable for a writing instrument. Preferably the viscosity of the ink composition of the present invention is less than 500,000 cPs at 20° C. More preferably the viscosity of the ink composition of the present invention is from about 1000 to about 50,000 cPs at 20° C. Most preferably, the viscosity is from about 2000 to about 30,000 cPs at 20° C.
The organic solvent may be used alone or in the form of a mixture between two or more organic solvents. Examples of solvents include, but are not limited to, alcohols, polyols, polyol ethers, ketones, esters, pyrrolidones, lactones, hydrocarbons or mixtures thereof. Preferably, the organic solvent(s) is present in an amount from about 1 to about 90 weight percent of the ink c
Chen Qingping
Nowak Michael T.
Bic Corporation
Pennie & Edmonds LLP
Shosho Callie
LandOfFree
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