Polyester Resin Coating for Metal Plate Shock Resistance
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Solution Overview
Problem
Existing methods for coating metal surfaces with polyester resins face challenges in achieving uniform thickness, close adhesion, and shock resistance, particularly when subjected to high-temperature and high-humidity conditions, and often require the use of ionomer resins that can lead to yield issues due to coagulation.
Innovation Solution
A polyester resin with a dimeric acid content of 2 to 10 mol % and a weight average molecular weight of 70,000 to 160,000, incorporating isophthalic acid and ethylene glycol, which provides excellent film-forming properties and shock resistance without the need for ionomer resins, ensuring close adhesion and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a generally employed polyester resin is used for extrusion lamination, then the coating speed is very high and cost is decreased, but the film swings and pulsates making it difficult to form a coating layer of uniform thickness
Solution Approach 1:
The patent changes the molecular weight parameter of the polyester resin from conventional low molecular weight to high molecular weight (70,000-160,000), which fundamentally alters the flow and coating characteristics of the resin during extrusion lamination, eliminating film swinging and pulsation while maintaining high coating speed
2Strength
If a polyester resin with high shock resistance is developed, then dent resistance is improved, but the film-forming property and adhesion may be compromised
Solution Approach 1:
The patent optimizes the molecular weight parameter to a specific range (70,000-160,000) which simultaneously provides high shock resistance and excellent film-forming properties, eliminating the need to trade off between these properties
Solution Approach 2:
The patent creates a composite resin system by combining high molecular weight polyester with specific additives including ionomer resin (5-20 parts by weight), tocopherol (0.01-1 part by weight), and other functional additives that work synergistically to enhance both shock resistance and film-forming properties
3Strength
If ionomer resin is blended with polyester resin to improve shock resistance, then dent resistance is enhanced, but the ionomer resin coagulates to form lumps causing yield loss
Solution Approach 1:
The patent changes the molecular weight parameter of the polyester resin to a high range (70,000-160,000) which fundamentally alters the compatibility and mixing characteristics with ionomer resin, preventing coagulation and lump formation while maintaining the shock resistance benefits
Solution Approach 2:
The patent applies local quality control by precisely controlling the distribution and concentration of ionomer resin (5-20 parts by weight) within the polyester matrix, ensuring uniform dispersion and preventing localized coagulation while maximizing shock resistance
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 enables the production of resin-coated metal plates with improved shock resistance, corrosion resistance, and flavor-retaining properties, maintaining high yields and performance under severe working conditions and retort sterilization.
Implementation Method 1
It has been widely known to utilize the heat-melting property of the thermoplastic resin for sticking the metal substrate and the thermoplastic resin together as represented by a method of sticking a pre-formed film of a thermoplastic polyester resin or the like onto a metal plate by heat-adhesion
Implementation Method 2
a method of sticking a thin molten film of a thermoplastic polyester or the like that is extruded onto the metal plate
Data Source
AI summary
A polyester resin for metal plate coating which contains a dimer acid in an amount of 2 to 10 mol %, as a dicarboxylic acid component and has a weight average molecular weight (Mw) ranging from 70,000 to 160,000. Thus, there can be provided a polyester resin for metal plate coating that has not only excellent film forming capability and corrosion resistance but also excellent impact resistance. Further, there can be provided a resin-coated metal plate excelling in properties, such as corrosion resistance, impact resistance (dent resistance), workability and flavor, and provided, fabricated from the resin-coated metal plate, a metal can and can lid.