Resin Layered Body Thermoformability via Glass Transition Tuning

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Solution Overview

Problem

Existing resin layered bodies composed of acrylic and polycarbonate resins face challenges in low-temperature thermoformability and are prone to interference fringes, whitening, and cracking during thermoforming processes.

Innovation Solution

A resin layered body is developed, comprising a polycarbonate-based resin with a specific molecular structure and a thermoplastic resin blend of methacrylic and styrene copolymers, optimized for low-temperature thermoformability and reduced interference fringes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the molding temperature is raised to enable sufficient expansion of the polycarbonate resin, then the thermoformability is improved, but the acrylic resin layer receives excessive heat causing detachment, whitening, and cracking at the interface

Engineering Contradiction:

ImprovethermoformabilityVSAvoidinterface integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the glass transition temperature parameter of the acrylic resin layer from its conventional value to specifically 100°C or higher (preferably 110-160°C). This parameter change allows the acrylic resin to maintain sufficient rigidity at lower molding temperatures, enabling thermoforming at temperatures that do not cause excessive heat damage to the acrylic layer while still allowing the polycarbonate layer to expand sufficiently.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the molding temperature is lowered to prevent whitening and cracking, then the interface integrity is maintained, but the polycarbonate resin does not expand sufficiently causing spring back

Engineering Contradiction:

Improveinterface integrityVSAvoidthermoformability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention modifies the glass transition temperature parameter of the acrylic resin to 100°C or higher, which fundamentally changes the thermal behavior of the layered body. This enables the system to achieve sufficient polycarbonate expansion at lower molding temperatures without causing acrylic resin detachment or damage, thereby resolving the spring back issue while maintaining interface integrity.

Inventive Principle:

Principle #35Parameter changes

3Strength

If a conventional acrylic resin layer is used in the layered body, then the surface hardness and transparency are maintained, but the resin is prone to detachment and cracking during low-temperature thermoforming

Engineering Contradiction:

Improvesurface hardnessVSAvoidthermoformability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the glass transition temperature parameter of the acrylic resin from conventional values (typically below 100°C) to 100°C or higher. This parameter modification allows the acrylic resin to maintain its surface hardness and transparency properties while gaining sufficient thermal stability for low-temperature thermoforming processes, preventing detachment and cracking.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite layered body where the acrylic resin layer with modified glass transition temperature (100°C or higher) is combined with the polycarbonate resin layer. This composite structure leverages the enhanced thermal properties of the modified acrylic resin to enable low-temperature thermoforming while maintaining the surface hardness and transparency characteristics of acrylic resins.

Inventive Principle:

Principle #40Composite materials

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 achieves excellent low-temperature thermoformability, preventing whitening and cracking, and reducing the occurrence of interference fringes, resulting in a molded product with a favorable appearance.

Implementation Method 1

the glass transition temperature of the thermoplastic resin (B) is 100°C or higher

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 2

a sheet has to be heated to a temperature at which the polycarbonate resin expands sufficiently

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4005771B1Transparent resin multilayer body, and transparent substrate material and transparent protective material each using same

Publication Date: 2025.04.23 MITSUBISHI GAS CHEM CO INC

AI summary

The present invention provides a resin layered body comprising: a layer containing a polycarbonate-based resin (A); a layer containing a thermoplastic resin (B) on at least one surface of the layer containing a polycarbonate-based resin (A); and a hard coating layer on a surface of the layer containing a thermoplastic resin (B) on at least one side, wherein the polycarbonate-based resin (A) has a glass-transition temperature of from 115°C to 140°C, the thermoplastic resin (B) comprises a methacrylic resin (C) and a styrene copolymer (D), a content of the methacrylic resin (C) is from 5 to 70 parts by mass and a content of the styrene copolymer (D) is from 95 to 30 parts by mass based on 100 parts by mass of a total content of the methacrylic resin (C) and the styrene copolymer (D), and the styrene copolymer (D) is a copolymer comprising a vinyl aromatic monomer unit (dl) in an amount of from 68 to 84 mass% and a cyclic acid anhydride monomer unit (d2) in an amount of from 16 to 32 mass%.