Decorative Sheet Warpage Control via Linear Expansion Coefficient Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Decorative sheets laminated with multiple resin sheets often suffer warpage during three-dimensional processing, leading to issues such as falling off from the mold, resin permeation, and peeling between sheets, which complicates the injection molding process.
Innovation Solution
A decorative sheet with two resin sheets laminated on each other, having a difference in linear expansion coefficient of 4×10−5/° C. (41 to 50° C.) or less, with at least one patterned layer intervening, and using specific materials like polyurethane, polyester, and acrylonitrile-butadiene-styrene resin, and employing methods like dry or hot laminating to prevent warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple resin sheets are laminated to create a decorative sheet, then the decorative functionality is improved, but warpage occurs during three-dimensional processing
Solution Approach 1:
The patent controls the linear expansion coefficients of the resin sheets to fall within specific ranges (first sheet: 5.0-15.0×10^-5/℃, second sheet: 8.0-18.0×10^-5/℃, difference: 1.0-5.0×10^-5/℃) to minimize thermal expansion differences during processing, thereby preventing warpage while maintaining multi-layer decorative functionality
Solution Approach 2:
The patent uses composite resin sheet structures with specific material combinations (first resin sheet from polyurethane, polyester, or acrylonitrile-butadiene-styrene resin; second resin sheet from polypropylene, polyethylene, or polystyrene) to achieve compatible thermal expansion properties while providing decorative patterns and functionality
2Shape
If the decorative sheet is subjected to three-dimensional processing by vacuum molding, then the sheet can follow the mold depression, but warpage causes the sheet to fall off from the mold
Solution Approach 1:
By controlling the linear expansion coefficients of the resin sheets within specific ranges and ensuring their difference is 1.0-5.0×10^-5/℃, the patent minimizes differential thermal expansion during vacuum molding, allowing the sheet to conform to the mold depression without warping or falling off
3Shape
If the decorative sheet is placed in the mold and three-dimensionally processed, then the sheet can follow the mold depression, but resin permeates the gap between the sheet and mold
Solution Approach 1:
The patent controls the linear expansion coefficients of the resin sheets to minimize differential expansion during processing, ensuring the sheet maintains uniform contact with the mold surface and prevents gaps that would allow resin permeation
4Adaptability or versatility
If multiple resin sheets with different materials are laminated, then the decorative functionality is enhanced, but warpage becomes more conspicuous
Solution Approach 1:
The patent specifies narrow ranges for linear expansion coefficients (first sheet: 5.0-15.0×10^-5/℃, second sheet: 8.0-18.0×10^-5/℃) and limits their difference to 1.0-5.0×10^-5/℃, enabling the use of different resin materials for decorative purposes while minimizing warpage through controlled thermal expansion properties
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 prevents warpage, ensures easy mold release, maintains adhesion, and prevents resin permeation, resulting in improved yield and reduced defects in injection-molded articles.
Implementation Method 1
the first resin sheet having a linear expansion coefficient of 5.0×10−5/° C. (41 to 50° C.) or more and 15.0×10−5/° C. (41 to 50° C.) or less, and the second resin sheet having a linear expansion coefficient of 8.0×10−5/° C. (41 to 50° C.) or more and 18.0×10−5/° C. (41 to 50° C.) or less, and a difference in linear expansion coefficient between the sheets of 1.0×10−5/° C. (41 to 50° C.) or more and 5.0×10−5/° C. (41 to 50° C.) or less
Data Source
AI summary
A decorative sheet for injection-molding and decorating a resin simultaneously, the decorative sheet containing two resin sheets laminated on each other with at least one patterned layer intervening therebetween, and the two resin sheets having a difference in linear expansion coefficient of 4×10−5/° C. (41 to 50° C.) or less. Even after subjecting to three-dimensional processing, such as vacuum molding, the decorative sheet suffers no warpage, and can be easily released from a mold for the three-dimensional processing, and even when the decorative sheet is set in a mold for injection molding, the decorative sheet does not fall off from the mold, a resin injected does not permeate a gap between the outer surface of the decorative sheet and the mold, and the decorative sheet suffers no peeling between the sheets constituting the decorative sheet.