Water-Soluble PVA Film Crystallinity Control
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Solution Overview
Problem
Water-soluble PVA films used for packaging chemicals face challenges in maintaining mechanical strength while ensuring good water sealing properties and high water solubility, as excessive crystallization reduces sealing strength and mechanical strength.
Innovation Solution
The water-soluble film is optimized by controlling the crystallinity indices of the surface layer and internal areas within a specific range, using a combination of polyvinyl alcohol-based resin, plasticizers, and other additives to achieve balanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the degree of crystallization is reduced to increase water solubility, then water solubility is improved, but mechanical strength is reduced and the film may deform or break during storage and transport
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the surface layer and internal layer have different crystallinity indices. The surface layer has a controlled crystallinity index Fs1 calculated by ATR-FTIR using a diamond prism, while the internal layer has a different crystallinity index Fi1. This allows the surface to provide water solubility while the internal structure maintains mechanical strength, resolving the contradiction between solubility and strength.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the crystallinity index parameters Fs1 and Fi1 within specific ranges. By adjusting these crystallinity parameters differently for the surface and internal layers, the invention achieves optimal balance between water solubility (improved by lower crystallinity) and mechanical strength (maintained by higher crystallinity in the internal structure).
2Strength
If the degree of crystallization is excessively high, then mechanical strength is maintained, but sealing strength is reduced when line speed is increased in continuous water sealing
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the surface layer and internal layer have different crystallinity indices. The surface layer has a controlled crystallinity index Fs1 calculated by ATR-FTIR using a diamond prism, while the internal layer has a different crystallinity index Fi1. This allows the surface to provide water solubility while the internal structure maintains mechanical strength, resolving the contradiction between solubility and strength.
Solution Approach 2:
The patent uses parameter changes by precisely controlling the crystallinity index parameters Fs1 and Fi1 within specific ranges. By adjusting these crystallinity parameters differently for the surface and internal layers, the invention achieves optimal balance between water solubility (improved by lower crystallinity) and mechanical strength (maintained by higher crystallinity in the internal structure).
Data Source
AI summary
Provided are a water-soluble PVA film having good water sealing properties in addition to excellent water solubility while maintaining mechanical strength of the water-soluble PVA film and a package using the same. A water-soluble film of the present invention includes a polyvinyl alcohol resin. When a crystallinity index calculated using a diamond prism is Fd1 and a crystallinity index calculated using a germanium prism is Fg1 for FT-IR measurement of a first surface of the water-soluble film by ATR technique, Fd1 and Fg1 are 0.25≤Fd1≤0.65 and Fd1/Fg1>1. Fd1 and Fg1 are preferably Fd1/Fg1≤1.5.