Sheet Manufacturing Apparatus for Precision Watermark Formation
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Solution Overview
Problem
Current paper-making methods, both slurry and dry, require significant labor and cost to change watermark designs due to the need for modifying molds or rolls, and these methods do not efficiently form detailed watermarks with high precision.
Innovation Solution
A sheet manufacturing apparatus that forms watermarks by adding water and applying heat and pressure, using a liquid application unit with an inkjet method to precision-add water, and a pressuring unit to suppress bleeding, allowing for easy design changes and sharper watermark definitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional mold or roll methods are used to form watermarks, then watermark formation is achieved, but design changes require making and changing molds or rolls, increasing labor and cost
Solution Approach 1:
The patent replaces the mechanical mold/roll system with a liquid application system that deposits water or liquid composition onto the sheet during the drying process. This substitution allows digital control of watermark patterns without physical contact, enabling easy design changes by simply modifying the liquid deposition pattern rather than manufacturing new molds or rolls.
Solution Approach 2:
The patent changes the physical state and composition parameters by applying liquid (water or liquid composition) to specific areas of the sheet during drying. By controlling the liquid application amount, position, and timing, different watermark designs can be created without changing the physical mold structure, thus enabling flexible design changes with minimal labor and cost.
2Adaptability or versatility
If water is added to form watermarks, then design flexibility is improved, but bleeding occurs in the water-added area, reducing watermark sharpness
Solution Approach 1:
The patent controls the liquid application parameters (amount, concentration, timing) to optimize watermark formation while minimizing bleeding. By adjusting these parameters, sharp watermark edges are achieved despite the liquid deposition process.
Solution Approach 2:
The patent applies liquid to the sheet during the drying process before the sheet is fully formed. This timing allows the liquid to be deposited on relatively dry fibers, reducing immediate bleeding while the sheet continues to dry and set the watermark pattern with sharp boundaries.
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
Enables the creation of detailed watermarks with high precision and easy design changes, enhancing the clarity and density of the watermark areas, reducing labor and cost associated with traditional methods.
Implementation Method 1
a liquid application unit that adds water by an inkjet method, for example, to part of the precipitate laid by the air-laying unit
Implementation Method 2
heating and compressing the web to which water was added by the liquid application unit, thereby forming sheets having parts with different light transmittance
Implementation Method 3
The sheet manufacturing apparatus according to this aspect of the invention adds water after compressing the laid web, thereby suppressing bleeding in the area where water is added
Implementation Method 4
The sheet manufacturing apparatus thus comprised can strengthen, by means of nanofiber, the hydrogen bonds between fibers contained in the web and the first sheet
Data Source
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AI summary
A sheet manufacturing apparatus having: a defibrating unit configured to defibrate, in air, feedstock containing fiber; a mixing unit configured to mix, in air, resin with the fiber defibrated from the feedstock by the defibrating unit; an air-laying unit configured to lay a web from the mixture output from the mixing unit; a wetting unit configured to add water to part of the web laid by the air-laying unit; and a sheet forming unit configured to form a sheet with parts having different light transmittance by heating and compressing the web to which water was added by the wetting unit.