Thermal Direct Printing Dissolving Paper Coating
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Solution Overview
Problem
There is a need for commercially viable water soluble/water dispersible labels that can be printed using direct thermal printing, as existing solutions require embossing and are not suitable for continuous surface coating.
Innovation Solution
A specific coating is applied to water dissolvable/dispersible paper that allows for direct thermal printing and is itself dissolvable, eliminating the need for embossing and ensuring the coating can be applied uniformly without deteriorating the paper, using a reverse gravure coating method followed by rapid drying to prevent paper degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thermosensitive coating is applied to water-soluble paper for direct thermal printing, then the label can be printed by thermal direct printing, but the coating prevents water penetration to the water-soluble adhesive and paper, making the label non-dissolvable
Solution Approach 1:
The coating material's chemical composition is changed from traditional thermosensitive materials (like iron stearate) to a water-soluble alternative containing a water-soluble dye and thickening agent. This parameter change allows the coating to maintain thermal printability while gaining water solubility, enabling both printing functionality and dissolvability to coexist without requiring embossing openings.
2Reliability
If embossing is used to create penetrating openings in the coating, then water can penetrate to the water-soluble film and adhesive, but the coating surface is no longer continuous and uniform
Solution Approach 1:
Instead of creating physical openings through embossing, the invention changes the fundamental parameter of the coating material to be water-soluble. This eliminates the need for embossing entirely, as water can penetrate the coating through dissolution rather than physical openings, maintaining a continuous, uniform coating surface while achieving water penetration.
3Manufacturing precision
If an aqueous coating is applied to water dissolvable paper, then the coating can be applied uniformly, but the water in the coating causes partial dissolving of the paper during the coating process
Solution Approach 1:
The coating process is designed to be rapid, with the aqueous coating applied and immediately dried using heated rollers. The quick application and rapid drying minimize the time the paper is exposed to water, allowing uniform coating application while preventing significant paper deterioration through shortened exposure duration.
Solution Approach 2:
The coating process utilizes phase transition of water from liquid to vapor through rapid heating and drying. The heated rollers quickly evaporate the water from the aqueous coating, transforming it from a liquid state that could dissolve the paper to a vapor state, leaving behind the solid coating material on the paper surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the production of labels that can be printed uniformly and easily removed with water, improving label application efficiency in industries like food service by allowing direct thermal printing on water dissolvable/dispersible paper without paper deterioration.
Implementation Method 1
the coating which, when applied to the water dissolvable or water dispersible paper, is itself water dissolvable
Implementation Method 2
using a reverse gravure coating method followed by rapid drying to prevent paper degradation
Implementation Method 3
Thermal direct printing is well known in the art and comprises a plurality of dot-producing heating elements which produce heat in response to energy applied thereto in order to print a series of dots
Data Source
AI summary
A label has a water dissolvable or water dispersible paper with a coating of a type which can be printed with direct thermal printing. The label is produced by passing a length of such paper with a freshly applied coating of the above type through an oven for drying before the coating has an opportunity to deteriorate the surface of the paper.