Heat-Shrinkable Polyester Film Roll for Core Wrinkle Reduction
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Solution Overview
Problem
Existing heat-shrinkable polyester films with a longitudinal shrinkage direction suffer from wrinkles around the winding core, leading to handling difficulties and increased film loss during processing, especially when thin films are used, which also compromise stiffness and handling properties.
Innovation Solution
The film composition includes ethylene terephthalate as a main component, with specific diol and dicarboxylic acid ratios, and incorporates additives like fine particles to enhance stiffness and reduce wrinkles, along with controlled production processes such as extrusion, drawing, and slitting to achieve optimal film properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If film thickness is reduced to reduce waste, then material loss decreases, but film stiffness deteriorates and handling becomes more difficult
Solution Approach 1:
The patent uses a multilayer composite structure combining polyester resin layers with different properties (heat-shrinkable layer and non-shrinkable layer) to achieve both thinness and sufficient stiffness for handling, while reducing overall material consumption
Solution Approach 2:
Different regions of the film structure have different stiffness characteristics - the heat-shrinkable polyester layer provides necessary rigidity where needed, while other layers contribute to flexibility and handling properties, allowing thin overall thickness without sacrificing handling capability
2Volume of moving object
If film is wound tightly into a roll for storage and transport, then space efficiency improves, but wrinkles form around the winding core
Solution Approach 1:
The film is pre-treated with specific resin compositions and structural configurations before winding that prevent wrinkle formation during the rolling process, allowing tight winding without surface defects
Solution Approach 2:
The patent modifies physical-chemical parameters of the film (resin composition, molecular structure, mechanical properties) to reduce natural shrinkage and improve dimensional stability, enabling wrinkle-free rolling at high density
3Productivity
If heat-shrinkable polyester film with longitudinal shrinkage direction is used for high-speed mounting, then mounting efficiency improves, but wrinkles appear around the winding core during storage
Solution Approach 1:
The patent optimizes resin composition ratios and molecular structure parameters to reduce natural shrinkage in the longitudinal direction, preventing wrinkle formation during storage while preserving the heat-shrinkable properties needed for high-speed automated mounting
Solution Approach 2:
The multilayer composite structure balances the heat-shrinkable properties needed for automated mounting with structural stability to prevent wrinkles during storage and transport
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 resulting film roll exhibits reduced wrinkles around the winding core, improved handling, and lower film loss during processing, maintaining stiffness and enabling high-speed mounting without defects.
Implementation Method 1
Heat-shrinkable polyester film having a longitudinal direction as the main shrinkage direction
Data Source
AI summary
In order to reduce the occurrence of wrinkling on a winding core part for a film roll formed by winding a heat-shrinkable polyester film for which a thinned longitudinal direction is a primary shrinkage direction, this heat-shrinkable polyester film roll is obtained by winding a heat-shrinkable polyester film on a paper tube, the film having a primary shrinkage direction that is the longitudinal direction and having a shrinkage rate in the primary film shrinkage direction of 40% or more following treatment in hot water at 90°C for 10 seconds, wherein the heat-shrinkable polyester film and the film roll satisfy the following conditions (1) to (7): (1) The film winding length is 1000 to 30000 m; (2) The film width is 50 to 1500 mm; (3) The film thickness is 5-30 pm; (4) The thickness irregularity at a surface layer part of the film roll in the entire film width direction is 20% or less; (5) The paper tube has an inner diameter of 3 inches, the difference in clearance of the paper tube in the width direction after the film is removed from the film roll is 0.5 mm or less, and the flat compressive strength of the paper tube after the film is removed is 1700 N/100mm or more; (6) The mean value of the winding hardness of the surface layer part of the film roll in the width direction is 500-850; and (7) The natural shrinkage rate in the longitudinal direction is 2.0% or less after 28 consecutive days of exposing the film in an atmosphere at a temperature of 40°C and relative humidity of 85%.