Vinyl Alcohol Polymer High-Speed Coatability
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Solution Overview
Problem
Existing vinyl alcohol-based polymers used in paper coatings face challenges with high-speed coatability, water resistance, and adhesiveness to release layers, particularly when used in high-shear applications, leading to issues like coating stripe formation and reduced barrier performance.
Innovation Solution
A vinyl alcohol-based polymer with a saponification degree of 70 mol% or more, containing ethylenic double bonds, is used in an aqueous solution with specific viscosity and molecular weight ranges to enhance coatability, water resistance, and adhesiveness, characterized by a molar ratio of ethylenic double bonds to vinyl alcohol and vinyl acetate units between 0.05/100 to 2/100, and satisfying certain viscosity and molecular weight formulas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silyl group-containing vinyl alcohol-based polymer is used to improve barrier performance, then barrier performance is improved, but adhesiveness to silicone layer is insufficient and viscosity is equivalent to or higher than common PVA, leading to poor high-speed coatability
Solution Approach 1:
The patent modifies the chemical structure of vinyl alcohol-based polymer by introducing ethylenic double bonds at specific positions (0.05-2 per 100 vinyl alcohol units) and controlling saponification degree (70-95 mol%), which changes the polymer's chemical parameters to simultaneously achieve good adhesiveness to silicone layers and maintained barrier performance, while reducing viscosity for high-speed coating
2Ease of operation
If a vinyl alcohol-based polymer with double bond introduced by acetalization is used to improve adhesiveness, then adhesiveness is improved, but viscosity is equivalent to or higher than common PVA, leading to poor high-speed coatability
Solution Approach 1:
The patent controls the concentration of ethylenic double bonds within a specific range (0.05-2 per 100 vinyl alcohol units) and maintains saponification degree between 70-95 mol%, which optimizes the balance between adhesiveness and viscosity. This parameter optimization allows the polymer to provide good adhesiveness while maintaining low enough viscosity for high-speed coating operations
3Productivity
If a vinyl alcohol-based polymer prepared by polymerizing vinyl ester at higher temperature is used to improve high-speed coatability, then high-speed coatability is improved, but water resistance is lower than common PVA
Solution Approach 1:
The patent optimizes saponification degree to 70-95 mol% and controls ethylenic double bond content at 0.05-2 per 100 vinyl alcohol units, which modifies the polymer structure to maintain water resistance while improving high-speed coatability. The specific parameter ranges prevent excessive chain scission that would compromise water resistance while still providing sufficient chain mobility for high-speed coating
4Productivity
If coating speed is increased to improve productivity, then productivity is improved, but viscosity of aqueous solution must be reduced, creating a contradiction with maintaining barrier performance
Solution Approach 1:
The patent modifies the molecular structure of vinyl alcohol-based polymer by introducing ethylenic double bonds and controlling saponification degree, which changes the polymer's rheological properties to achieve lower viscosity while maintaining barrier performance. This structural modification allows the coating solution to flow more easily at high speeds while the polymer chains still provide effective barrier properties when deposited
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 provides excellent high-speed coatability, improved water resistance, and enhanced adhesiveness to release layers, ensuring uniform coating and barrier performance while maintaining low viscosity for efficient application.
Implementation Method 1
an aqueous solution comprising a vinyl alcohol-based polymer having an ethylenic double bond with a saponification degree of 70 mol% or more... a limiting viscosity [η] and a weight-average molecular weight Mw of a vinyl ester-based polymer which is produced by esterifying the vinyl alcohol-based polymer satisfy the following formulas (1) and (2)
Implementation Method 2
a vinyl alcohol-based polymer... containing ethylenic double bonds... enhanced adhesiveness to release layers... a molar ratio of the ethylenic double bond to the total of vinyl alcohol units and vinyl acetate units is 0.05/100 to 2/100
Implementation Method 3
a vinyl alcohol-based polymer with a saponification degree of 70 mol% or more... prepared by polymerizing a vinyl ester at a temperature higher by 2 to 80 °C than a boiling point of a reaction solution and saponifying the vinyl ester-based polymer obtained
Implementation Method 4
improved water resistance, and enhanced adhesiveness to release layers, ensuring uniform coating and barrier performance... high barrier performance is required... the PVA in the release paper serves as a barrier for preventing an expensive silicone from permeating a substrate
Data Source
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AI summary
There is provided a vinyl alcohol-based polymer having an ethylenic double bond with a saponification degree of 70 mol% or more, wherein the vinyl alcohol-based polymer is water-soluble; a molar ratio of the ethylenic double bond to the total of vinyl alcohol units and vinyl acetate units is 0.05/100 to 2/100; and a limiting viscosity [η] and a weight-average molecular weight Mw of a vinyl ester-based polymer which is produced by esterifying the vinyl alcohol-based polymer satisfy the following formulas (1) and (2). 4.7≤logMw≤6.3 0.60<logη+3.75/logMw<0.69