U.S. Patent No. 3,389,108, granted on June 18, 1968, to Morris L. Smith, Guido Roccheggiani, and Robert W. Faessinger, describes an ultra-low-viscosity, water-based printing fluid engineered for ultra-high-speed rotogravure printing on absorbent paper products. The inventors—Morris L. Smith of Lawnside, New Jersey, Guido Roccheggiani of Bala Cynwyd, Pennsylvania, and Robert W. Faessinger of Media, Pennsylvania—assigned the patent to the Scott Paper Company of Delaware County, Pennsylvania.
This specific invention solved a severe industrial bottleneck in paper goods manufacturing: traditional rotogravure printing used thick, pigmented inks diluted in volatile, flammable solvents. At commercial manufacturing speeds, these legacy inks caused severe abrasive wear to intaglio cylinders, created massive fire and environmental hazards, required energy-intensive drying stations, and caused “fiber picking” or cylinder web-wrapping whenever press speeds exceeded standard operational limits. Smith, Roccheggiani, and Faessinger developed an aqueous, non-abrasive, self-curing solution that eliminated organic solvent carriers and enabled high-fidelity printing on unsized paper webs at speeds up to 5,000 feet per minute (nearly a mile a minute).
The Innovation: The Self-Curing Vinylsulfonium-Dye System
The core breakthrough lies in replacing suspended solid pigment particles with a completely water-soluble, synergistic chemical complex: an electropositive (cationic), thermosetting vinylsulfonium polymer resin paired with a compatible water-soluble anionic dye.
Rather than relying on mechanical evaporation of volatile solvents to leave behind a dry pigment crust, this printing fluid chemically integrates into the paper matrix. The cationic vinylsulfonium resin exhibits an intrinsic electrostatic affinity for electronegative cellulose fibers. As the ink strikes the paper, the resin forms salt bonds with both the cellulose matrix and the anionic dye molecules. Upon air-drying or light heating, the resin undergoes self-crosslinking into an insoluble, three-dimensional polymer network that locks the dye into the paper fibers.
Why Vinylsulfonium Resins?
- Ultra-Low Viscosity (Less Than 20 cps): The resin dissolves completely in water to yield a non-dilatant fluid with water-like fluidity, eliminating cylinder drag, web sticking, and fiber picking at multi-thousand-foot-per-minute press velocities.
- Non-Abrasive Cylinder Life: Because the fluid is a true molecular solution entirely free of suspended pigment particulates, abrasive wear against chrome-plated gravure rolls and doctor blades is virtually eliminated.
- Fast Molecular Fixation (Low Transference): The resin cures at room temperature within weeks or accelerates under heat (below 350°F) in seconds, binding dye molecules permanently to yield high colorfastness with bleed resistance (transference values between 0 and 4).
- Extended Solution Stability: By utilizing excess stoichiometric ratios of cationic resin relative to the dye, the inventors prevented premature precipitation, achieving shelf stability ranging from several hours to over four months.
Key Chemical Components
The printing fluid is formulated as an aqueous solution comprising specific polymers, reactive dyes, and functional performance modifiers:
| Component | Chemical Classification | Function in Printing Fluid |
| Thermosetting Vinylsulfonium Resin | Cationic polymer derived from ethylenically unsaturated sulfines | Acts as the primary binder; crosslinks with itself, cellulose fibers, and dye molecules to render the imprint water-insoluble. |
| Water-Soluble Anionic Dye | Direct, acid, or fiber-reactive dyestuff | Provides tinctorial strength and color without particulate abrasion; chemically bonds to cationic resin sites. |
| Water Carrier | Aqueous solvent base | Serves as the primary non-toxic, non-flammable carrier, replacing high-vapor-pressure volatile organic solvents. |
| Solution Stabilizers | Glycols, glycol ethers (Cellosolve/Carbitol), formamide, DMF, or DMSO | Improves resin-dye solution stability and shelf-life, particularly at low resin-to-dye solid ratios. |
| Dye Solubilizers | Urea | Enhances dye dissolution and prevents dyestuff crystallizing out of concentrated solution. |
| Surfactants | Non-ionic polyoxyethylene adducts (e.g., nonylphenoxypoly(ethylene oxide)) | Regulates surface tension and enhances fluid transfer from chrome-plated intaglio roll cells to paper webs. |
Performance: High-Speed Web Printing Metrics
The patent demonstrates that this water-soluble polymer fluid overcomes the mechanical and rheological barriers of prior-art pigmented inks:
Operational Comparison
- Press Velocity: Prior-art solvent inks were strictly rate-limited due to ink tackiness, roll wrapping, and solvent flash-off requirements. The vinylsulfonium formulation operates reliably at web velocities up to 5,000 ft/min and higher.
- Viscosity Constraints: Operates with a stable viscosity at 77°F of less than 20 centipoises (cps), preventing shear-thickening or dilatant drag across the doctor blade.
- Transference Value (Bleed Resistance): Evaluated under standardized wet-contact migration tests, achieving low transference ratings from 0 to 4, indicating virtually complete dye immobilization on the cellulosic web.
- Substrate Compatibility: Optimized for absorbent, unsized papers having water absorbency rates faster than 600 seconds per 0.01 ml of water—specifically suited for facial tissue, multi-ply bathroom tissue, paper towels, and napkins.
The Chemical and Curing Process
The inventors established a defined sequence for formulating and fixing the printing fluid:
- Polymer Synthesis: Prepare water-soluble vinylsulfonium polymers or interpolymers (e.g., copolymerizing sulfonium acrylates or methacrylates with acrylamides, acrylates, or vinyl amides to yield at least 10 to 99 mole percent sulfine groups).
- Solution Blending: Dissolve the vinylsulfonium resin in water in stoichiometric excess relative to the chosen water-soluble anionic dye to suppress ionic flocculation.
- Stabilization & Wetting Tuning: Blend in polar stabilizing additives (such as ethylene glycol or urea) and non-ionic wetting agents to tailor surface tension for chrome intaglio transfer.
- Intaglio Deposition: Transfer the fluid via a rotogravure cylinder directly onto an unsized, absorbent cellulosic web running at industrial web velocities up to 5,000 ft/min.
- Cross-Linking Fixation: Allow the printed web to self-cure at ambient temperatures (up to 4 weeks) or accelerate cure through forced hot-air drying below 350°F, forming a durable, non-bleeding three-dimensional polymer-fiber network.
About the Inventors and Scott Paper Company
The patent represents a joint innovation by research chemists at the Scott Paper Company’s technological research facilities in Pennsylvania:
- Morris L. Smith: An inventive chemist based in Lawnside, New Jersey, who specialized in paper chemistry, polymer treatments, and industrial coloring processes for commercial web products.
- Guido Roccheggiani and Robert W. Faessinger: Research associates who co-authored numerous foundational patents in water-soluble resins, wet-strength additives, and synthetic polymer coatings.
- Scott Paper Company Legacy: Headquartered in Delaware County, Pennsylvania, Scott Paper was an international leader in sanitary paper tissue products. This patented technology allowed the company to introduce vibrant, bleed-proof decorative printing patterns onto high-absorbency paper towels and bath tissues at high production rates without stiffening paper softness or introducing hazardous solvent emissions into manufacturing plants.
Summary of Claims
The patent explicitly claims:
- An aqueous printing fluid comprising a solution of a water-soluble, self-curing, thermosetting vinylsulfonium polymer resin and a water-soluble dye compatible with the resin.
- Formulations where the fluid possesses a viscosity at 77°F of less than approximately 20 cps, a transference value between 0 and 4, and solution stability from one hour to in excess of four months.
- The application of the aqueous vinylsulfonium printing composition to unsized cellulosic paper webs moving at speeds up to approximately 5,000 feet per minute.
- Printed absorbent paper products bearing an insolubilized, crosslinked reaction product of the vinylsulfonium resin, water-soluble dyestuff, and cellulosic fibers.
