Polyimide Spacer Anisotropy for Glass Panel Thermal Insulation

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Solution Overview

Problem

Conventional glass panel units face challenges in achieving low thermal conductivity and impact resistance due to the high thermal conductivity of metal spacers and the lack of anisotropy in thermal conductivity in existing materials, which affects their thermal insulation and structural integrity.

Innovation Solution

The use of polyimide-based spacers with a benzoxazole structure, oriented in an orthogonal direction to the counter direction, which have a higher thermal conductivity ratio in the orthogonal direction, providing both high strength and low thermal conductivity, thereby enhancing thermal insulation and impact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal spacers are used to maintain vacuum space thickness, then structural strength is improved, but thermal conductivity increases and thermal insulation deteriorates

Engineering Contradiction:
Improvestructural strengthVSAvoidthermal insulation
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent changes the material parameters of the spacer by using polyimide with specifically oriented molecular chains. The molecular chains are oriented such that thermal conductivity in the counter direction (λc) is reduced while maintaining mechanical strength, achieving λo/λc ≥ 1.5. This parameter change in thermal conductivity anisotropy resolves the contradiction between strength and thermal insulation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure within the spacer material by combining polyimide base material with benzoxazole structural units and specifically oriented molecular chains. This composite approach creates a material that simultaneously provides high strength through the polyimide structure and low thermal conductivity in the counter direction through the oriented molecular chains with λo/λc ≥ 1.5.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If spacers with low thermal conductivity are used, then thermal insulation is improved, but impact resistance and structural integrity deteriorate

Engineering Contradiction:
Improvethermal insulationVSAvoidimpact resistance
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The patent changes the thermal conductivity parameters by creating anisotropic material properties through molecular chain orientation. The spacer material exhibits low thermal conductivity in the counter direction (λc) while maintaining adequate mechanical strength, achieving the ratio λo/λc ≥ 1.5. This resolves the contradiction by directing low thermal conductivity specifically where needed for thermal insulation while preserving strength properties.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional spacer materials are used, then ease of manufacture is improved, but thermal conductivity anisotropy and directional thermal insulation are insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoiddirectional thermal insulation
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent changes the manufacturing parameter by specifying a minimum ratio λo/λc ≥ 1.5 for the spacer material rather than requiring complex geometric configurations. This parameter-based approach simplifies manufacturing by focusing on material property control through molecular chain orientation during extrusion or molding, while achieving the desired directional thermal insulation performance.

Inventive Principle:
Principle #35Parameter changes

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 polyimide-based spacers effectively reduce thermal conductivity in the counter direction while maintaining high compressive strength and impact resistance, improving the overall thermal insulation and structural integrity of the glass panel units.

Implementation Method 1

a ratio of a thermal conductivity in the orthogonal direction to a thermal conductivity in the counter direction is higher than or equal to 1.5

Methodology Applied
Scientific EffectThermal conductivity anisotropy: Anisotropy

Implementation Method 2

Of the molecular chains, a number of molecular chains oriented in an orthogonal direction is larger than a number of molecular chains oriented in a counter direction

Methodology Applied
Scientific EffectHeat conduction through molecular chains: Conduction (thermal)

Data Source

PatentEP3438064B1Glass panel unit
Publication Date: 2023.12.06 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3438064B1 patent drawingFigure 1
  • EP3438064B1 patent drawingFigure 2
  • EP3438064B1 patent drawingFigure 3A~3C

AI summary

An object of the present invention is to provide a glass panel unit having a reduced thermal conductivity in a counter direction in which a first glass panel and a second glass panel face each other. A glass panel unit (10) according to the present invention includes a first glass panel (20) and a second glass panel (30) disposed to face the first glass panel (20). The glass panel unit (10) includes: a seal (40) having frame shape and hermetically binding the first glass panel (20) and the second glass panel (30) together; and a depressurized space (50) surrounded by the first glass panel (20), the second glass panel (30), and the seal (40). The glass panel unit (10) includes spacers (70) disposed between the first glass panel (20) and the second glass panel (30). The spacers (70) include a macromolecular resin material including molecular chains (71). Of the molecular chains (71), the number of molecular chains (71) oriented in an orthogonal direction (92) is larger than the number of molecular chains (71) oriented in a counter direction (91). The orthogonal direction (92) is a direction orthogonal to the counter direction (91), the counter direction (91) being a direction in which the first glass panel (20) and the second glass panel (30) face each other.