Low-Temperature Heat Seal Coating for Polymeric Substrates
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Solution Overview
Problem
Current heat seal coatings for polymeric substrates require high temperatures for sealing and lack satisfactory hot tack properties, often requiring additional primers for adhesion, which limits their effectiveness and versatility.
Innovation Solution
A coating comprising a copolymer of ethylene and acrylic or methacrylic acid combined with an aliphatic polyurethane emulsion, along with optional additives like wetting agents, matting agents, and antiblocking agents, providing low temperature heat sealability and high hot tack without the need for additional precoatings, and suitable for various polymeric substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heat seal coatings are used, then adhesion to polymeric substrates is achieved, but sealing temperatures must be at least 90°C and hot tack properties are unsatisfactory
Solution Approach 1:
The patent applies composite materials by combining ethylene acrylic acid copolymer (50-90 wt%) with vinyl alcohol vinyl acetate copolymer (10-50 wt%) to create a heat seal coating that achieves both low temperature sealing (75-140°C) and satisfactory hot tack properties. The synergistic interaction between the two polymer components resolves the contradiction between lowering sealing temperature and maintaining hot tack performance.
2Ease of manufacture
If conventional heat seal coatings are applied, then heat sealability is provided, but additional primers are required to enhance adhesion to the film surface
Solution Approach 1:
The patent extracts the adhesion enhancement function from a separate primer coating and integrates it directly into the heat seal coating formulation. The ethylene acrylic acid copolymer provides inherent adhesion to polymeric substrates like BOPP, eliminating the need for additional primer layers and simplifying the overall coating system while maintaining strong adhesion.
3Strength
If the coating provides strong adhesion to the substrate, then heat sealability is improved, but the coating may become too tacky and cause blocking during storage
Solution Approach 1:
The patent applies local quality by incorporating antiblocking agents (5-20 wt% of waxes, silica, or crosslinking agents) into specific regions of the coating formulation to provide non-tacky surfaces during storage while maintaining strong adhesion during heat sealing. The ethylene acrylic acid copolymer provides adhesion strength, while the added antiblocking agents prevent surface blocking, creating different functional zones within the coating system.
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
Enables heat sealing at lower temperatures (75°C to 140°C) with strong adhesion and high hot tack, eliminating the need for primers and reducing solvent use, while maintaining printability and forming a durable seal on diverse substrates.
Implementation Method 1
a coating which provides low temperature heat sealability and high hot tack to such polymeric substrates
Implementation Method 2
heat sealing at lower temperatures (75°C to 140°C)
Implementation Method 3
the strength of the heat seal provided when the coating is heated to a temperature at or above the melting point of the polymer coating
Data Source
Figure 1A~2
AI summary
A coating is provided for enhancing low temperature heat sealability and providing high hot tack to polymeric substrates. The coating is water-based and includes a dispersion of a copolymer of ethylene and acrylic or methacrylic acid, and a compatible adhesion enhancer which is an aliphatic polyurethane emulsion. The coating may also include additives such as wetting agents, matting agents, antiblocking agents, and tackifying resins. The coating may be applied to a variety of polymeric substrates and may be heat sealed to itself, or to polymeric substrates, cellulosic substrates, and metal substrates.