Polyvinyl Acetal Interlayer Film for Laminated Glass
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Solution Overview
Problem
Interlayer films made of polyvinyl acetal for laminated glass face issues with discoloration due to heating, generation of foreign materials, and deterioration in penetration resistance, which affect the evenness of light-diffusing properties and safety.
Innovation Solution
A polyvinyl acetal interlayer film with an acetalization degree of 60 to 80 mol%, containing 0.1 to 20 mol% vinyl ester monomer units and a viscosity-average degree of polymerization of 1400 to 4000, with light-diffusing fine particles dispersed to maintain non-agglomerated state, and incorporating a plasticizer like triethylene glycol di(2-ethylhexanoate), ensuring refractive index differences and specific molecular weight ratios for enhanced stability and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polyvinyl acetal interlayer film is used for laminated glass, then light-diffusing properties can be achieved, but discoloration occurs due to heating
Solution Approach 1:
The patent applies parameter changes by precisely controlling the acetalization degree (60-80 mol%) and viscosity-average degree of polymerization (1400-4000) of the polyvinyl acetal. These parameter optimizations enable the interlayer film to maintain both light-diffusing properties and resistance to heating-induced discoloration, resolving the contradiction between optical performance and thermal stability.
2Illumination intensity
If polyvinyl acetal interlayer film is used, then light-diffusing properties can be achieved, but foreign materials are generated
Solution Approach 1:
The patent optimizes the viscosity-average degree of polymerization to 1400-4000 and acetalization degree to 60-80 mol%, which prevents foreign material generation during processing while maintaining the light-diffusing properties. This precise parameter control resolves the contradiction between achieving optical functionality and preventing harmful foreign material generation.
3Illumination intensity
If polyvinyl acetal interlayer film is used for safety laminated glass, then light-diffusing properties can be achieved, but penetration resistance deteriorates
Solution Approach 1:
The patent achieves a balance between light-diffusing properties and penetration resistance by optimizing the viscosity-average degree of polymerization (1400-4000) and acetalization degree (60-80 mol%). These parameter adjustments ensure that the interlayer film maintains sufficient strength for safety applications while preserving optical diffusion capabilities.
4Illumination intensity
If fine particles are highly dispersed in polyvinyl acetal interlayer film, then even light-diffusing properties can be achieved, but dispersibility is insufficient
Solution Approach 1:
The patent optimizes the viscosity-average degree of polymerization (1400-4000) and acetalization degree (60-80 mol%) of the polyvinyl acetal to improve the dispersibility of light-diffusing fine particles. These parameter adjustments enable uniform particle distribution throughout the interlayer film, achieving even light-diffusing properties without particle agglomeration.
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 a polyvinyl acetal interlayer film that is resistant to discoloration, contains fewer foreign materials, and exhibits excellent penetration resistance and light-diffusing properties, maintaining transparency and safety in laminated glass applications.
Implementation Method 1
A structure provided with light-diffusing properties by adding fine particles can diffuse light emitted from a point light source such as an electric bulb and an LED or a line light source such as a fluorescent tube and allow the light to emit to a planar direction
Implementation Method 2
an interlayer film for a laminated glass containing a polyvinyl acetal, the film being made of a composition comprising a polyvinyl acetal with an acetalization degree of 60 to 80 mol%, a content of a vinyl ester monomer unit of 0.1 to 20 mol%, and a viscosity-average degree of polymerization of 1400 to 4000
Implementation Method 3
a haze as measured in accordance with JIS K 7105 for a laminated glass prepared by sandwiching the interlayer film for a laminated glass between two transparent glass sheets with a thickness of 3 mm is 20 % or less, wherein a difference absolute value between a refractive index of the light-diffusing fine particles and a refractive index of the composition free from the light-diffusing fine particles is 0.20 or more
Data Source
Figure 1
AI summary
An objective of the invention is to provide: an interlayer which is for use in a laminated glass comprising a polyvinyl acetal, which is less discolored by heating and contains less foreign materials (undissolved materials), and in which light-diffusing fine particles are dispersed in a non-agglomerated state. Another objective is to provide a laminated glass, in which, even when the interlayer film for a laminated glass is produced after repeated heating, light-diffusing fine particles are dispersed in a non-agglomerated state, and which exhibits excellent penetration resistance, excellent transparency and excellent light-diffusing properties with the use of the interlayer film. There is provided an interlayer film for a laminated glass comprising a polyvinyl acetal with an acetalization degree of 60 to 80 mol%, a content of a vinyl ester monomer unit of 0.1 to 20 mol% and a viscosity-average degree of polymerization of 1400 to 4000, and light-diffusing fine particles, wherein a difference absolute value between a refractive index of the light-diffusing fine particles and a refractive index of the composition free from the light-diffusing fine particles is 0.20 or more and a haze as measured in accordance with JIS K 7105 for a laminated glass prepared by sandwiching the interlayer film for a laminated glass between two glass sheets with a thickness of 3 mm is 20 % or less, and the interlayer film for a laminated glass satisfies formulas (1) and (2): A−B/A<0.80 1.00×10−2<b/y/a/x<2.00×10−1