Electrostatic Adsorbable Sheet for Humidity-Resistant Display
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Solution Overview
Problem
Existing electrostatic adsorbable sheets for displaying printed materials on objects, such as posters and advertisements, face issues with durability, humidity sensitivity, ease of peeling, ink adhesiveness, and compatibility with various printing methods, leading to problems like pattern misalignment and dust accumulation during printing.
Innovation Solution
A laminate electrostatic adsorbable sheet comprising a label layer with a resin film and a recording layer on one surface, and a support layer, where both layers undergo electrically charging treatment, specifically using direct-current corona discharge, with the resin film containing a polyolefin resin and the recording layer having antistatic properties, ensuring high electrostatic adsorbability without external charge exhibition during printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous film is used to increase surface area and charge-holding ability, then electrostatic adsorbability is enhanced, but the film becomes sensitive to humidity and loses charge-retaining ability in high humidity conditions
Solution Approach 1:
The patent employs a porous polyolefin resin film where the porous structure provides large surface area for charge distribution while the hydrophobic nature of polyolefin resin reduces water absorption. The pores are filled with electret material that maintains electrostatic charges without being affected by humidity, thus resolving the contradiction between enhancing adsorbability and avoiding humidity sensitivity.
Solution Approach 2:
The patent creates a composite structure by incorporating electret material into the porous polyolefin resin film. This composite approach combines the advantages of porous structure (high surface area) with the humidity-resistant properties of electret material, achieving both enhanced electrostatic adsorbability and humidity insensitivity.
2Reliability
If high electrostatic adsorbability is given to the film, then the film can effectively attach to objects, but the film may stick to rolls and cause pattern misalignment during printing
Solution Approach 1:
The patent applies different properties to different parts of the system: the surface of the film that contacts the object to be attached has high electrostatic adsorbability, while the back side and edges are designed with controlled charge distribution to prevent unwanted sticking during handling and printing. This localized quality differentiation resolves the contradiction between strong attachment and printing stability.
3Strength
If adhesive agents or double-sided adhesive tapes are used to attach posters, then strong attachment is achieved, but the materials become difficult to peel and recycle
Solution Approach 1:
The patent replaces the chemical bonding mechanism of adhesive agents with an electrostatic field-based attachment mechanism. The electret film generates electrostatic forces that strongly attract to the object surface, providing attachment strength comparable to adhesives, but without chemical bonding that prevents peeling. This allows easy removal and recycling by simply peeling off the film without leaving residue.
4Reliability
If a recording layer is added to enable printing, then ink adhesiveness is improved, but the film may catch dust and get dirty during printing due to high electrostatic adsorbability
Solution Approach 1:
The patent applies local quality differentiation by providing the recording layer with antistatic properties specifically on the surface that receives printing, while maintaining electrostatic adsorbability on the opposite surface for attachment. This localized antistatic treatment prevents dust attraction during printing without compromising the electrostatic attachment function.
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 provides a sheet that maintains high electrostatic adsorbability over time, is not affected by humidity, can be easily peeled off, and is compatible with multiple printing methods, reducing issues like pattern misalignment and dust accumulation, while ensuring good ink adhesiveness and handling properties.
Implementation Method 1
the resin film layer (A) and the support layer (ii) are electrostatically adsorbed
Implementation Method 2
specifically using direct-current corona discharge
Implementation Method 3
use of an adsorption-type film that enables attaching by electrostatic force
Data Source
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AI summary
The present invention provides an electrostatic adsorbable sheet that can attach and display a printed material as it is on an object to be attached, as a poster, an advertisement or the like, has a high electrostatic adsorbability during display use, can be used for display over a long period of time with sufficient durability of the electrostatic adsorbability, has electrostatic adsorbability that is hardly affected by humidity, and can be easily peeled away after display use. In the electrostatic adsorbable sheet, since the electrostatic adsorbability is not exhibited externally before display use, troubles such as blocking of sheets themselves and attachment to a roll particularly in a printing step hardly occur, handlability is good, and the adhesiveness of ink is excellent, so that the sheet is compatible with a variety of printing methods. The present invention relates to an electrostatic adsorbable sheet (iii) which is a laminate comprising a label layer (i) containing a resin film layer (A) and a recording layer (B) on one surface of the resin film layer (A) and a support layer (ii), wherein at least one of the label layer (i) and the support layer (ii) is subjected to an electrically charging treatment, the resin film layer (A) and the support layer (ii) are electrostatically adsorbed, the surface resistivity of the label layer (i) side is from 1×10-1 Ω to 9x 1012 Ω, and the surface resistivity of the support layer (ii) side is from 1×10-1 Ω to 9×1012 Ω.