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The chemical watermark of the present invention is formed by replacing air entrained in a paper sheet with a material having an index of refraction reasonably close to that of cellulosic fibers.
The second method uses a polymer relief plate to apply a chemical that makes a faint image into the paper.
True watermarking is for large quantities of paper, and for smaller runs of 10,000 sheets and up the second method makes a "watermark" available to a wide range of end users.
There have been some disclosures of application of chemical watermarks to otherwise finished paper products. The curing reaction which renders the watermark insensitive to the water and common solvents may be effected in a shorter time span if the paper is heated to an elevated temperature after application of the chemicals but the obvious increased cost and increased degree of control which must be exercised over this type of process makes this option expensive and disadvantageous.
Generally, these processes have in common the steps of applying a chemical material in the form of a solution in a volatile solvent to the otherwise finished paper product, allowing or otherwise causing the solution to penetrate into the fiber structure of the sheet, and then removing the volatile solvent. 3,048,100 which is directed specifically to a chemical watermark produced by treating the paper with a cyclohexanone resin dissolved in a volatile solvent. The present invention provides a composition and process for forming a chemical watermark in otherwise finished paper and at the same time overcomes the disadvantages associated with previous types of chemical watermarking.
THERM-O-TYPE does not recommend using Aegis chemistry on any machine other than equipment produced by THERM-O-TYPE to apply Aegis Watermarks.
Customers who purchase watermark chemistry for use on non-THERM-O-TYPE watermark equipment do so at their own risk.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. A chemically watermarked product comprising a paper sheet having a watermark of preselected design applied to a portion thereof, said watermark having a refractive index approximating that of the paper and being an insoluble reaction product produced by irradiation of a synthetic resin with high frequency radiation above the visible spectrum. The product of claim 1 in which said resin composition includes a free radical polymerizable polyethylenically unsaturated monomer or prepolymer. The product of claim 2 in which said synthetic resin is an ester of an aliphatic polyhydric alcohol with at least 2 mols of an unsaturated carboxylic acid containing up to five carbon atoms per molecule. The product of claim 3 in which said acid is acrylic acid. The product of claim 3 in which said acid is methacrylic acid. The product of claim 3 in which said acid is itaconic acid. The product of claim 3 in which said composition also includes a photoinitiator. The method of applying a chemical watermark to paper which comprises applying to the surface of a finished paper a synthetic resin composition having a chemical grouping thereon capable of being insolubilized upon exposure to high frequency radiation, said resin composition being applied in the form of a preselected design in a preselected small area of the paper, said resin composition having a viscosity suitable for such coating and being insufficiently cross-linked to be chemically set, and thereafter exposing said resin composition to high frequency radiation above the visible spectrum to thereby insolubilize said resin composition. The method of claim 8 in which said high frequency radiation is rich in ultraviolet light. The method of claim 8 in which said composition also includes a photoinitiator. The method of claim 8 in which said composition is applied as a solvent solution. The method of claim 8 in which said synthetic resin composition includes a free radical polymerizable polyethylenically unsaturated monomer or a prepolymer. The method of claim 12 in which said synthetic resin is an ester of an aliphatic polyhydric alcohol with at least 2 mols of an unsaturated carboxylic acid containing up to 5 carbon atoms per molecule. The method of claim 13 in which said acid is acrylic acid. The method of claim 13 in which said acid is methacrylic acid. The method of claim 13 in which said acid is itaconic acid. Field of the Invention This invention is in the field of chemical watermarks, i.e., marks that are laid down upon paper products to provide a characteristic design to convey intelligence. DESCRIPTION OF THE PRIOR ART In the office operations of commercial enterprises, it is often desirable to have writing stationery and other forms of business and professional papers provided with a watermark.These watermarks are sometimes business trandemarks used to identify the manufacturer of the paper product or they may contain coded information that relates to dates of manufacture or composition.After the papermaking and watermarking process is complete, the finished paper may be cut into sheets of various sizes, for use as stationery or business papers of the like.Another known method of mechanically producing a watermark involves employing a band fitted about a roll and carrying the design or configuration of the watermark in relief.The solvent may be removed by evaporation or normal drying at ambient temperatures or by forced drying with the application of heat or forced air streams. The present invention provides chemical watermarks which are substantially insoluble and colorless.One of the earliest of such disclosures appears in Livingstone U. It provides a method for making chemical watermarks which involves applying a liquid chemical composition to the surface of otherwise finished paper and then curing the composition in the paper to render it insoluble to water and common solvents.There are two primary types of Watermarking processes in the industry.The first is performed when the paper is being made, whereby a brass screen with an image brazed onto the wire rotates on top of the still wet mat of paper fibers, impressing the image into the surface.THERM-O-TYPE will not guarantee the performance of Aegis chemistry used on non-THERM-O-TYPE equipment.THERM-O-TYPE will not be held liable for any loss of income or damage to equipment caused by customers using watermark chemistry on non-THERM-O-TYPE equipment.