Very little exist on history of ink manufacture because of 2 factors:
Early progress in ink development was very slow, with several centuries passing between improvements.
Most printers keep their formulations secret.
15th century Gutenberg boiled the linseed oil and natural
resin prior to adding pigment.
Result: Ink insoluble in water and enhanced ink bonding to page.
Gutenberg’ s ink formula cooking resin and linseed oil- created varnish to hold the lampblack- prototype of modern inks.
Gutenberg’ s ink formula was altered only modestly next 300 years.
18th century English printer John Baskerville- developed
blacker and more velvety ink.
18th century English patent first granted for making colored inks.
Until 19th century printers manufactured their own inks.
19th century rapid technological advance, improvement of
ink chemistry accelerated.
Agents for speeding ink drying rates.
Stiffness of varnishes became controllable.
Vegetable oils replaced varnishes on newspaper presses.
Heatset Printing: Invention of heatset inks – 1930’s.
Till then- most paste ink printing-sheetfed (mechanism of drying = oxidation 6-12 hrs).
Slow drying , because of that no fast runs.
Heatset inks : drying by combination of evaporation and penetration.
Contained 50% of a blend of petroleum hydrocarbons- narrow boiling range close to volatility of kerosene.
Hard resins (phenol-formaldehyde) were used instead of drying oils as binders, producing hard film.
Invention of web presses, speed 700 ft/min. Dried with metal drums heated with steam.
In the 1940’s - new types of inks and drying systems: Superheated stem
blown on the web
Operating principle of inks: setting & drying through absorption of water vapor from steam to ink. Resin, soluble in glycol precipitates with water, bind the pigment to the substrate.
These inks were widely used - low odor products (paper bread bags, waxed after printing).
Web Offset Inks
In the 1950’s litho presses redesigned from sheet-fed to web-fed.
Higher printing speed, different litho ink formulations.
Dried in seconds - by evaporation and penetration.
Similar solvents that were used in heatset letterpress, good water/ink balance, new synthetic resins - resisting fountain solution, maintaining good rheology of emulsified ink.
Inks- lower in tack to avoid picking.
Flexographic Film Inks
In the early 1960’s developed flexo ink able to adhere to new polyethylene
Flexo inks adhering to PE films for packaging markets.
New resin chemistry similar to NYLON- modified polyamide resins soluble in alcohol and hydrocarbons (for bread bags). Polyamide flexo inks became standard in packaging.
Energy Curing Inks
In the late 1960’s UV (ultraviolet) and EB (electron beam) curing inks
No solvent, no resin- dried “cured” instantly upon UV or EB energy.
Stable until exposed to appropriate energy- could be left on press for extended time.
UV inks- monomers & prepolymers of unsaturated chemicals, and photoinitiator.
The EB inks- no photoinitiator – higher energy of electron beam.
New equipment needed- to safely cure these inks on press.
New elastomer materials for rollers and blankets (old would be attacked with new formulations). Safehandling-skin, eye irritation.
Slower curing of black, or metallic inks.
High Speed Litho Inks
In the early 1980’s litho press doubled operational speed to 2,000ft
Lower tack, changed rheology - to avoid damage of paper surface.
Attention to rate and type of emulsification.
New types of binder resins for achieving proper emulsification.
New design of dryers- longer (1 sec dwelling time).
Rate of diffusion of heatset solvent through partially dried ink films.
Driving force in 1990’s :
Increasing regulatory pressures
Increasing local geographic and global competition
Competition from other communication media
Demand for improved production efficiency, consistent quality of printing
Many challenges to litho ink technology:
Current litho press speeds are 3,000 ft/min (15m/s).
Controlled dot gain and good uniformity of printed solids are needed.
Control of misting is needed (increases with speed of presses).
Wider water tolerance is desired.
Improvement of drying rates of ink in order to minimize the increased length of drying equipment.
Flexo water based technology has grown greatly, some problems remain:
Increased use of four color process demands better rheological control of formulations, dot gain control, color reproduction.
Increased drying speed, improving wetting and adhesion.
Research needed in innovative vehicle chemistry.
Reduction or elimination of monomers (source of residual odor, may be cause of skin, eye irritation).
Controlled oligomer and vehicle rheology.
Choice of proper vehicle material to change viscosity .
Development of new reactive chemicals to improve the economics.
Conventional litho market two-fluid printing –stable- a lot of presses installed.
Trends - waterless litho - single fluid without fountain solution.
New types of ink chemistry.
Press cooling systems will appear.
Coldset ink on uncoated paper- first candidate for self dampening litho.
Solvent based with the use of toluene - dominant - solvent recovery system - a must.
Replacement of existing hydrocarbon inks:
Water based inks -slower drying rates, press modifications required.
Phase-change inks (hot melts) -actively researched, needs proper rheology.
Must be run at elevated temperature – may limit the use of inks to new equipment
Change of hot-melts rheology to achieve good print properties.
Water based inks more than 50% market.
Gift wraps- 100% water based.
Solvent recovery and incineration as control methods.
Water based to replace letterpress newspaper printing.
Competition with Litho coldset market .
Increase its market share due to increased quality of 4-color process and good economics
Penetration of UV flexo inks, UV water reducible will continue to grow - narrow web, label printing.
Continue to grow –specialized nature of inks, in unique processes.
UV inks, both water reducible and 100% solids will increase.
Electrographic printing – Indigo, Xeikon, Docucolor, Spontane, various color copiers,
using “toner “ type of inks, both liquid and powder type.
Ink jet printing –continue to grow strongly.
Water based jet inks both dye and pigment type.
Other types- thermal transfer, sublimation, hot melt.