Crosslinked Polyvinyl Acetal Resin UV Irradiation Method
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Solution Overview
Problem
Conventional methods for producing cross-linked polyvinyl acetal resins require cross-linking agents, leading to instability in viscosity, sheet attack, and insufficient mechanical strength, especially in thermal transfer ink sheets and offset printing plates, which limits their application in high-speed printing and heat-resistant applications.
Innovation Solution
A method involving the irradiation of polyvinyl acetal resins with ultraviolet light of specific wavelengths (200-365 nm) to achieve cross-linking without the need for cross-linking agents, enhancing mechanical strength and solvent resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cross-linking agents are added to polyvinyl acetal resin to improve mechanical strength and solvent resistance, then the resin achieves cross-linking, but the viscosity becomes unstable and residues cause staining and degradation
Solution Approach 1:
The invention extracts and eliminates the cross-linking agent component from the system by using the resin's own functional groups (carboxyl, hydroxyl, or amino groups) to perform auto-cross-linking. This removes the source of viscosity instability and residues while maintaining the cross-linking function.
Solution Approach 2:
The polyvinyl acetal resin performs self-cross-linking through its own functional groups without requiring external cross-linking agents. The resin serves both as the base material and the cross-linking agent, eliminating composition instability and residue issues.
2Strength
If cross-linking agents are added to polyvinyl acetal resin to improve mechanical strength, then cross-linking occurs, but sheet attack and insufficient strength occur in thermal transfer ink sheets
Solution Approach 1:
The invention removes cross-linking agents from the system and replaces them with auto-cross-linking mechanisms using functional groups inherently present in the polyvinyl acetal resin, eliminating the source of sheet attack while maintaining strength.
Solution Approach 2:
The invention creates a composite cross-linked structure within the polyvinyl acetal resin by forming cross-links between functional groups (carboxyl, hydroxyl, or amino groups) of adjacent polymer chains, enhancing sheet integrity through internal reinforcement.
3Strength
If thermosetting cross-linking is used to improve mechanical strength, then cross-linking reaction proceeds, but the process becomes complicated and requires heating which may damage vulnerable materials
Solution Approach 1:
The invention replaces the thermal field (heating) with a chemical field mechanism where cross-linking occurs through chemical reactions between functional groups at ambient or lower temperatures, eliminating the need for complex heating equipment and processes.
Solution Approach 2:
The invention changes the cross-linking mechanism from thermal activation to chemical activation through functional group reactions, allowing cross-linking to proceed without high temperature heating, thus simplifying the process and protecting heat-sensitive materials.
4Strength
If electron beam or X rays are applied to cross-link polyvinyl butyral to improve mechanical strength, then cross-linking occurs, but the resin is decomposed
Solution Approach 1:
The invention extracts the need for high-energy radiation by using chemical cross-linking through functional groups, eliminating the harmful decomposition effect of electron beams and X-rays while achieving the desired cross-linking and strength enhancement.
Solution Approach 2:
The invention uses readily available functional groups (carboxyl, hydroxyl, amino) already present in the polyvinyl butyral resin for cross-linking, replacing the need for expensive and harmful high-energy radiation sources, thus achieving cross-linking through a safer, more economical chemical process.
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
This approach allows for the production of cross-linked polyvinyl acetal resins with high mechanical strength and excellent solvent resistance, addressing issues of sheet attack and heat resistance, and enabling their use in high-speed printing and heat-resistant applications without the complications of cross-linking agents.
Implementation Method 1
irradiating a polyvinyl acetal resin with ultraviolet light having a wavelength in a range of 200 to 365 nm to allow a cross-linking reaction to proceed
Data Source
AI summary
An object of the present invention is to provide a method for producing a cross-linked polyvinyl acetal resin, which can provide a cross-linked polyvinyl acetal resin having high mechanical strength and excellent solvent resistance by a simple method without a cross-linking agent, and can solve such problems as sheet attack, insufficient strength, and instability of viscosity for a long-time storage, and another object of the present invention is to provide a cross-linked polyvinyl acetal resin produced by the above method for producing a cross-linked polyvinyl acetal resin. The method for producing a cross-linked polyvinyl acetal resin comprises the step of irradiating a polyvinyl acetal resin at least having structural units represented by the following formulas (1) to (4) with ultraviolet light having a wavelength in a range of 200 to 365 nm,wherein R1 represents a hydrogen atom or a C1-C20 hydrocarbon group; and R2 represents a group having two or more functional groups, the two or more functional groups each selected from the group consisting of the functional groups represented by the following formulas (5), (6), and (7).