Laminated Polyester Film Scratch Resistance
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Solution Overview
Problem
Existing polyester films used in laminated metal sheets and light-blocking tapes face issues with scratch resistance during deep-drawn can production and adhesion of foreign substances, leading to quality and yield problems, and require improved processing suitability at high temperatures.
Innovation Solution
A laminated polyester film structure with a pigment-containing layer and wax-containing layers on both sides, having specific surface free energy and wax content distributions, and a melting point range to ensure good base coverage, scratch resistance, and printability, while maintaining detachability during molding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a white film is laminated on a metal sheet to provide base coverage property, then coverage property is improved, but scratch resistance during deep-drawn can production deteriorates
Solution Approach 1:
The film is divided into multiple functional layers: a pigment-containing polyester layer A for coverage property, and wax-containing polyester layers B1 and B2 for scratch resistance. Each layer performs its specific function independently, resolving the contradiction between coverage and scratch resistance.
Solution Approach 2:
The invention uses a composite laminated structure combining polyester resin with different functional additives (pigment in layer A, wax in layers B1 and B2) to achieve both coverage property and scratch resistance simultaneously. The composite structure allows each component to contribute its specific property.
2Ease of operation
If wax is included to improve releasability of content, then releasability is improved, but scratch resistance during production of deep-drawn cans deteriorates
Solution Approach 1:
Wax is localized specifically in the outer layers B1 and B2 where releasability is needed, while the inner layer A maintains pigment for coverage. The wax content per unit area in layers B1 and B2 is controlled to be greater than in layer A, creating local quality differentiation that satisfies both releasability and scratch resistance requirements.
3Force
If an adhesive layer is coated on the film for light-blocking tape application, then adhesion is improved, but foreign substance adhesion increases resulting in quality decrease
Solution Approach 1:
The surface free energy of the outer layers B1 and B2 is precisely controlled within a specific range (27-43 mN/m), and the wax content is optimized to achieve the right balance between adhesion for tape application and resistance to foreign substance adhesion. The coefficient of variation of water contact angle is controlled to ensure uniformity.
4Quantity of substance
If the film is made thinner to reduce material usage, then material consumption is reduced, but processing suitability at high temperature deteriorates
Solution Approach 1:
The laminated composite structure with specific layer thickness ratios provides sufficient high-temperature processing suitability even for thin films. The total thickness of layers B1 and B2 is controlled to be 5-50 μm, with their combined thickness being 1-50 times that of layer A, optimizing both thinness and thermal processing performance.
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 film achieves enhanced scratch resistance, reduced adhesion of foreign substances, and improved processing suitability at high temperatures, resulting in better quality and yield for deep-drawn metal sheets and light-blocking tapes.
Implementation Method 1
the surface free energy of each layer B1 and layer B2 is not less than 27 mN/m and not more than 43 mN/mm
Implementation Method 2
a pigment-containing polyester layer A... wherein the film satisfies formulae (I) and (II)... Wb1>Wa (I) and Wb2>Wa (II)
Implementation Method 3
the melting point of each of the polyester layer A, the polyester layer B1 and the polyester layer B2 is higher than 250° C. and equal to or lower than 280° C.
Data Source
AI summary
A laminated polyester film includes a pigment-containing polyester layer A and wax-containing polyester layers B1 and B2 on both sides of the polyester layer A, wherein the film satisfies formulae (I) and (II), and the coefficient of variation of water contact angle for each layer B1 and layer B2 is not less than 0% and not more than 10%, when the contact angle with water is measured 10 times at arbitrary defined positions within the range of 200 mm×200 mm:Wb1>Wa (I)Wb2>Wa (II)wherein Wb1 and Wb2 represent the wax content per unit area of the layer B1 and layer B2 respectively, and Wa represents the wax content per unit area of the layer A, and wherein the coefficient of variation represents a value obtained by dividing the standard deviation in values measured 10 times by the average value.