Engraved Roll Surface Control for Defect-Free Embossed Resin Sheet
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Solution Overview
Problem
Embossed thermoplastic resin sheets used as interlayer films in laminated glass often suffer from optical distortion due to defects in the projection patterns, which affect deaeration properties and visibility, as the existing methods of forming projections and recesses using engraved rolls can result in clogged blast material remaining in grooves, leading to defective transfers and abnormal projections.
Innovation Solution
An engraved roll with a controlled surface pattern, where the number of blast material pieces with a maximum length of 10 µm or more is limited to three per mm², is used to produce embossed thermoplastic resin sheets with reduced defects, ensuring accurate pattern transfer and improved deaeration properties without optical distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blasting glass beads onto the surface of the engraved roll is performed to form grooved embossment pattern, then deaeration properties are improved, but blast material remains clogged in grooves causing defective transfers and optical distortion
Solution Approach 1:
The patent applies preliminary action by performing a cleaning step before the embossing process. Specifically, the engraved roll surface is cleaned to remove blast material from grooves prior to transferring the embossment pattern to the thermoplastic resin sheet. This preliminary cleaning prevents defective transfers and ensures accurate pattern replication while maintaining the deaeration-enhancing grooved structure.
Solution Approach 2:
The patent applies the extraction principle by removing the harmful blast material from the grooves of the engraved roll. The cleaning process extracts the clogged particles from the recessed portions of the roll surface, eliminating the source of defects in the embossed pattern while preserving the functional grooved structure for deaeration.
2Reliability
If recesses with continuous bottom groove shape are formed regularly arranged in parallel, then deaeration properties are significantly improved, but optical distortion occurs due to film thickness variation
Solution Approach 1:
The patent applies local quality by creating different surface features in different locations. The embossed thermoplastic resin sheet has recesses with continuous bottom groove shapes arranged in parallel for deaeration, while the projections between recesses have controlled roughness (Ra ≤ 3.0 μm) to minimize optical distortion. This local differentiation allows the sheet to simultaneously achieve excellent deaeration properties and reduced optical distortion when viewed through laminated glass.
3Reliability
If multiple projections and recesses are formed on thermoplastic resin sheet surface, then deaeration properties are enhanced, but defects in projections cause optical distortion and lower visibility
Solution Approach 1:
The patent applies feedback by establishing a quality control mechanism that monitors and limits the number of defective projections. The specification defines clear criteria for defects (projections with Ra > 3.0 μm) and sets an acceptable limit (not more than three defects per mm²). This feedback control ensures that the embossed sheet maintains both enhanced deaeration properties and acceptable optical quality for laminated glass applications.
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 significantly reduces the occurrence of defective transfers, resulting in embossed thermoplastic resin sheets with fewer surface defects, enhancing deaeration properties and suppressing optical distortion in laminated glass, thereby improving visibility.
Implementation Method 1
an engraved roll having an uneven pattern including projected ridges and recessed grooves arranged on a surface in parallel with one another in a circumferential direction... transferring the uneven pattern to a thermoplastic resin sheet
Data Source
Figure 1(a)~2(b)
Figure 3(a)~5(b)
Figure 6
AI summary
The present invention aims to provide an embossed thermoplastic resin sheet that is capable of enhancing deaeration during production of laminated glass and suppressing optical distortion of the resulting laminated glass to improve the visibility when used as an interlayer film for laminated glass. The present invention also relates to an engraved roll used for production of the embossed thermoplastic resin sheet, a production method of the engraved roll, an interlayer film for laminated glass including the embossed thermoplastic resin sheet, and a laminated glass. The present invention relates to an embossed thermoplastic resin sheet having a large number of recesses and a large number of projections on at least one surface, the recesses each having a groove shape with a continuous bottom and being regularly arranged side by side in parallel with one another, the thermoplastic resin sheet having not more than three defects of the projections per mm2 on the surface.