Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-05-26
2003-11-11
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031360, C106S031370, C106S031400, C106S031580, C106S031490, C106S031600, C106S031860, C106S031780, C106S031680, C106S031690, C106S031720
Reexamination Certificate
active
06645280
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention pertains to ink jet ink compositions in general, and in particular, to an ink jet ink composition that is useful in printing watermarks on paper substrates.
BACKGROUND OF THE INVENTION
It is often desirable to include watermarks in stationeries, business forms, and other papers. Advantages of watermarks are many. For example, a trademark can be placed on the paper in the form of a watermark to identify the paper manufacturer. Watermarks also can be provided to contain coded information relating to the dates of manufacture or the composition of the paper. As watermarks generally do not reproduce on photocopying machines, they can serve as document authenticating tools.
Watermarks are traditionally created by processes involving the use of mechanical means. For example, a watermark can be produced during the paper-making process by compressing the wet paper fibers between rolls having a raised design such as a design containing letters or drawings. After the compression is completed, the paper fibers are dried. The compression of the fibers displaces a significant amount of the air trapped in the fibers and renders the compressed region thinner, denser, and more transparent than the uncompressed region. Such processes have many disadvantages, for example, they use heavy machinery or do not allow frequent changes in the design of watermarks. To change the design of a watermark, the compression rolls may have to be changed, which can be laborious and expensive. Further, as small orders cannot be processed readily, to make it economically worthwhile, customers desiring to have a stationery watermarked are often required to place large orders.
Other processes for creating watermarks have been proposed, for example, by the use of printing inks. JP 58108189 A discloses a watermark printing method. The abstract of this patent application describes the purpose of the method as follows: “To obtain easily a paper with a transparent pattern, having processability even in small amounts, by a method in which printing is performed on paper by using an SAIB solution while heating and then heated further.” “SAIB” herein refers to sucrose acetate isobutyrate. U.S. Pat. No. 3,985,927 discloses “compositions and method for producing chemical watermarks in finished paper products, the watermarks being produced by applying to the surface of the paper a synthetic resin composition having a chemical grouping therein capable of being insolubilized upon exposure to high frequency radiation, and thereafter exposing the resin composition to such high frequency radiation to insolubilize the resin,” (abstract). U.S. Pat. No. 5,847,024 discloses a watermark ink “composed of a drying oil modified polyester, an aluminum alkoxide gelling agent and an ultraviolet light absorber” (abstract). The preferred ink has a viscosity of at least 150 poise (column 3, lines 21-22). According to Example 2 of the '024 patent, the ink is applied to the substrate by wet lithography.
Many of the known methods are cumbersome or difficult to practice as, e.g., they involve multiple steps or use heat or ultraviolet radiation. The printing speed also may not be high in some of these methods. The watermarks printed by some of these methods are also unstable to heat or light.
Thus, there exists a need for a method for providing watermarks at high speeds. There further exists a need for a method for providing watermarks which allows frequent changes in the design of the watermark. There also exists a need for ink compositions that can be employed to print watermarks at high speeds. There also exists a need for ink compositions capable of printing watermarks that are stable to heat and/or light.
The advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The foregoing needs have been fulfilled to a great extent by the present invention which provides a jet ink composition suitable for printing watermarks on paper substrates. The jet ink composition comprises a solvent and a translucentizing agent. The present invention further provides a method for printing watermarks on a substrate such as paper, the method comprising projecting a stream of droplets of the ink composition and controlling the direction of the stream so that the droplets form an image on the substrate. The method of the present invention has an advantage that the printing speed is high. The method is versatile and allows changes in the design of watermarks to be readily incorporated. The watermarks have good contrast and are stable to heat and light.
While the invention has been described and disclosed below in connection with certain embodiments and procedures, it is not intended to limit the invention to those specific embodiments. Rather it is intended to cover all such alternative embodiments and modifications as fall within the spirit and scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a jet ink composition that is suitable for printing watermarks on paper substrates. The watermarks have excellent contrast on paper substrates. The watermarks do not bleed or yellow upon aging. The present invention also provides a method for printing watermarks on paper substrates. The watermark is usually viewed under light transmitted through the paper, preferably substantially perpendicular to the paper. When viewed in this manner, the watermark appears lighter than the unmarked area.
The jet ink composition of the present invention comprises a solvent and one or more translucentizing agents. The translucentizing agent makes the paper less opaque, and thus forms a visible image on the paper when viewed under light.
The jet ink composition of the present invention can be employed in continuous or drop on demand ink jet printers. When used in a continuous ink jet (CIJ) printer, the jet ink composition has (1) a viscosity of from about 1.6 to about 10.0 centipoises (cP) at 25° C.; (2) an electrical resistivity of from about 50 to about 2000 ohm-cm; and/or (3) a sonic velocity of from about 1100 to about 1700 meters/second. When used in a drop on demand ink jet printer, the viscosity of the ink composition can be up to about 50 cP or more and preferably from about 3.0 cP to about 30 cP at 25° C.
Any suitable translucentizing agent can be used. The translucentizing agent preferably has a refractive index close, e.g., within about ±0.1-0.3 refractive index units, and more preferably within about ±0.1 refractive index unit, to that of the paper substrate, particularly to that of cellulose. Cellulose has a reported refractive index of 1.54. Typically, the translucentizing agent has a refractive index of from about 1.3 (±0.05) to about 1.7, and preferably from about 1.4 to about 1.6, at 20° C. The translucentizing agent preferably has good thermal and light stability, e.g., without bleeding or a significant change in color. The translucentizing agent preferably has hydrolytic stability, e.g., it does not degrade when exposed to heat and moisture. The translucentizing agent preferably has a low moisture absorbance, e.g., not more than that of paper.
The translucentizing agent preferably has low volatility, e.g., a weight loss of about 5% or less, and preferably about 2% or less when heated at 171° C. for 50 hours. The translucentizing agent preferably does not seep out of the watermark with time. The translucentizing agent preferably has good penetration into paper substrates.
The translucentizing agent can be one or more high molecular weight materials, one or more low molecular weight materials, or a combination thereof. Typically, the high molecular weight material has a weight average molecular weight of less than 50,000, and preferably from about 2,000 to about 40,000. Typically, the low molecular weight material has a weight average molecular weight of less than 2000, and preferably from about 500 to about 1500. The lower molecular weig
Peterson Christopher D.
Zhu Linfang
Faison Veronica F.
Klemanski Helene
Videojet Technologies Inc.
LandOfFree
Jet ink composition for printing watermarks does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Jet ink composition for printing watermarks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Jet ink composition for printing watermarks will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3141269