Modified Polyvinyl Alcohol Film for Chemical Packaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polyvinyl alcohol (PVA) films used for packaging chemicals, especially alkaline or chlorine-containing compounds, suffer from solubility loss, stiffness issues, and chemical resistance degradation over time, failing to meet performance requirements for cold water solubility and mechanical strength.
Innovation Solution
A modified polyvinyl alcohol containing 0.05 to 10 mol% of a monomer unit with two carboxyl groups, where specific integrals in 1H-NMR spectroscopy satisfy a predetermined condition, is used to produce a water-soluble film with enhanced cold water solubility, strength, and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If partially-saponified unmodified PVA is used to achieve high cold water solubility, then solubility is improved, but chemical resistance deteriorates over time when packaging alkaline or acidic materials
Solution Approach 1:
The invention changes the chemical composition parameters of PVA by introducing specific monomer units (itaconic acid with 0.05-5.0 mol% and maleic acid with 0.05-5.0 mol%) to modify the polymer structure. This parameter change enables the film to maintain both high cold water solubility and chemical resistance by creating a balanced molecular structure that resists saponification while remaining water-soluble.
Solution Approach 2:
The invention creates a composite polymer structure by copolymerizing vinyl acetate with unsaturated dicarboxylic acids (itaconic acid and maleic acid). This composite material approach combines the water-solubility characteristics of PVA with the chemical resistance properties of the dicarboxylic acid units, achieving both desired properties simultaneously.
2Reliability
If partially-saponified unmodified PVA is used to achieve high cold water solubility, then solubility is improved, but mechanical strength and stiffness are insufficient due to low crystallinity
Solution Approach 1:
The invention modifies the crystallinity parameter by incorporating itaconic acid and maleic acid units that promote ordered molecular packing. The specific molar ratios and structural characteristics of these monomers enhance intermolecular interactions, increasing crystallinity from the low levels in unmodified PVA to sufficient levels for mechanical strength while preserving water solubility.
3Strength
If completely-saponified PVA with high degree of saponification is used to improve mechanical strength through higher crystallinity, then strength is improved, but cold water solubility decreases due to higher content of crystalline portion insoluble in cold water
Solution Approach 1:
The invention optimizes the degree of saponification parameter by introducing itaconic acid and maleic acid units that maintain water solubility even at high saponification degrees (80-99.9 mol%). These dicarboxylic acid units create molecular structures that prevent excessive crystallization, allowing the film to achieve both high mechanical strength and high cold water solubility simultaneously.
Data Source
Figure 1
AI summary
The present invention provides: a water-soluble film that is superior in cold water solubility and in practical properties such as strength and stiffness and that can resist deterioration in various properties such as chemical resistance over time; and a modified polyvinyl alcohol used for the water-soluble film. The present invention relates to a modified polyvinyl alcohol containing 0.05 to 10 mol% of a monomer unit having two carboxyl groups. In 1H-NMR spectroscopy of the modified polyvinyl alcohol, an integral (X) from 6.8 to 7.2 ppm and an integral (Y) from 5.3 to 5.5 ppm satisfy the following expression: 0.60≤X/X+Y<1.0.