Laminated Glass Interlayer Film for Low Yellowing Heat Shielding
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Solution Overview
Problem
Conventional laminated glass interlayer films often exhibit high yellow index values (YI) and excitation purity, and insufficient heat shielding properties, particularly when thickness variations occur, and large wedge angles exacerbate these issues.
Innovation Solution
A two-layer interlayer film with a first layer containing tungsten oxide particles or tin-doped indium oxide particles as heat shielding compounds and an ultraviolet ray screening agent, and a thermoplastic resin, where the thickness varies gradually from one end to the other, with a rectangular or wedge-like sectional shape, to achieve low YI and high heat shielding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional interlayer film is used, then the manufacturing process is simple, but the yellow index value becomes high and heat shielding properties are insufficient
Solution Approach 1:
The patent uses a composite interlayer film structure combining PVB resin with heat shielding particles (ITO or ATO) dispersed throughout. This composite material approach enables the film to simultaneously achieve good optical properties (low YI value) and effective infrared heat shielding, resolving the contradiction between manufacturing simplicity and heat shielding performance.
Solution Approach 2:
The patent modifies the interlayer film by controlling the particle size distribution (D10, D50, D90 parameters) and concentration of heat shielding particles. By optimizing these parameters, the film achieves sufficient heat shielding properties while maintaining low yellow index values, thus improving heat shielding without compromising manufacturing feasibility.
2Object-affected harmful factors
If the thickness of the interlayer film is increased to improve heat shielding, then the heat shielding properties are enhanced, but the yellow index value and excitation purity increase
Solution Approach 1:
The patent employs heat shielding particles with specific local size distributions (D10=0.5-2.0 μm, D50=2.0-5.0 μm, D90=5.0-10.0 μm) to achieve effective infrared shielding. The optimized particle size distribution ensures that heat shielding functionality is concentrated in specific particle size ranges, preventing excessive thickness and yellowing while maintaining effective heat blockage.
Solution Approach 2:
The patent uses inorganic heat shielding particles (ITO or ATO) that replicate the heat shielding function of thicker organic films. These particles provide equivalent or superior infrared blocking performance at thinner film thicknesses, thereby preventing yellow index increase while achieving the required heat shielding properties.
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 interlayer film achieves a balanced low YI value, low excitation purity, and high heat shielding properties despite thickness variations, effectively suppressing double images in head-up displays and enhancing visibility in vehicles.
Implementation Method 1
The energy amount of an infrared ray with a wavelength of 780 nm or more which is longer than that of visible light is small as compared with that of an ultraviolet ray. However, the thermal action of infrared rays is large, and when infrared rays are absorbed into a substance, heat is released from the substance.
Implementation Method 2
an interlayer film including tin-doped indium oxide particles (ITO particles) or antimony-doped tin oxide particles (ATO particles)
Data Source
Figure 1(a)~1(b)
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AI summary
There is provided an interlayer film for laminated glass with which a low yellow index value, low excitation purity and high heat shielding properties can be achieved in spite of the thickness varying with places. The interlayer film for laminated glass according to the present invention has a two or more-layer structure, has a thickness of one end thinner than a thickness of the other end at the opposite side of the one end and includes a first layer containing a thermoplastic resin and a second layer containing a thermoplastic resin, the difference between the maximum thickness and the minimum thickness in the first layer is smaller than the difference between the maximum thickness and the minimum thickness in the second layer, and the first layer contains a heat shielding compound.