Water-Soluble Substrate Coating Resists Premature Dissolution
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Solution Overview
Problem
Water-soluble substrates used in packaging materials, such as pouches, tend to disintegrate or become sticky when exposed to small amounts of water or high humidity, leading to leakage and failure to fully dissolve during use.
Innovation Solution
A water-soluble substrate with a coating that has an elongation ratio of at least 1, covering at least one surface, ensuring resistance to water exposure before immersion, while allowing quick dissolution in aqueous solutions, using polymeric materials like polyvinyl alcohol and water-insoluble coatings like liquid polyurethane or acrylic-based coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a water-soluble substrate is used for packaging, then it can dissolve quickly in water for easy disposal, but it disintegrates and becomes sticky when exposed to small amounts of water or high humidity during storage
Solution Approach 1:
A coating layer comprising 5-50 wt% polyvinyl alcohol and 50-95 wt% water-insoluble particulate material is applied to the water-soluble substrate. The water-insoluble particulate material acts as a mediator that retards water penetration to the substrate during storage, while still allowing complete dissolution when immersed in sufficient water. This intermediary layer resolves the contradiction by providing storage stability without compromising dissolution speed.
Solution Approach 2:
The invention creates a composite structure combining water-soluble substrate with a coating layer containing both polyvinyl alcohol and water-insoluble particulate materials. This composite material approach allows the coating to exhibit dual functionality: water resistance during storage and water solubility during dissolution, thereby resolving the contradiction between storage stability and dissolution speed.
2Reliability
If the water-soluble substrate is coated with water-insoluble material to prevent premature dissolution, then storage stability improves, but the coating may break during stretching processes causing water contact with the substrate
Solution Approach 1:
The coating formulation is optimized with specific polyvinyl alcohol content (5-50 wt%) that provides flexibility and elongation capacity. The polyvinyl alcohol component allows the coating to stretch with the substrate without breaking, while the water-insoluble particulate material provides water resistance. This parameter optimization resolves the contradiction between storage stability and coating integrity during stretching.
Solution Approach 2:
The coating layer is designed with a specific composition gradient where polyvinyl alcohol provides local flexibility and adhesion to accommodate stretching, while water-insoluble particulate material provides local water resistance. This local quality differentiation within the coating allows it to maintain integrity during stretching while providing storage stability.
3Reliability
If a thick coating is applied to prevent water contact, then storage stability improves, but the substrate fails to dissolve completely in water
Solution Approach 1:
The coating is formulated with controlled thickness and composition (5-50 wt% polyvinyl alcohol, 50-95 wt% water-insoluble particulate material) that allows water to penetrate through the coating to reach the substrate. The polyvinyl alcohol component is water-soluble and facilitates water penetration, ensuring complete dissolution while the water-insoluble particulate material provides sufficient water resistance during storage. This parameter control resolves the contradiction between storage stability and dissolution completeness.
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 coated substrate maintains integrity against accidental water contact and humidity, preventing premature dissolution and leakage, while ensuring rapid dissolution in wash water, enhancing the usability and storage stability of packaged contents.
Implementation Method 1
the elongation ratio of said coating to said water-soluble substrate is at least 1
Implementation Method 2
coated with a particulate or fibrous water-insoluble material
Implementation Method 3
water-soluble substrate... can subsequently dissolve very quickly when immersed in an aqueous solution
Implementation Method 4
polymeric materials like polyvinyl alcohol
Data Source
AI summary
A water-soluble substrate, and more particularly a water-soluble substrate that is resistant to dissolution, and methods of making the same are disclosed. The water-soluble substrate comprises a first surface and a second surface. A coating is applied to, and substantially covers at least one of said first and second surfaces. The elongation ratio between said coating and said water-soluble substrate is at least 1. Articles, such as pouches, made from the water-soluble substrate, are also disclosed herein.