Polycarbonate Acrylic Laminated Sheet Thermoforming Defects
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Solution Overview
Problem
Polycarbonate resin sheets used in thermoforming often experience issues such as peeling, whitening, cracking, and bubble formation due to excessive heat, and lamination failures when combined with an acrylic resin layer, particularly during deep-draw molding, and the use of polymer alloys can lead to decomposition and defects like black spots and bumps.
Innovation Solution
A laminated synthetic resin sheet with a polycarbonate resin substrate layer having a viscosity-average molecular weight of 18,000-35,000 and a coating layer containing an acrylic resin, where the monohydric phenol terminating agent is represented by specific formulas, exhibiting strain softening properties and a glass-transition temperature difference within 30°C with the acrylic resin, preventing excessive heating and enhancing thermoformability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polycarbonate resin layer is laminated with an acrylic resin layer to improve surface hardness, then surface damage resistance is improved, but peeling occurs at the interface during thermoforming due to excessive heat
Solution Approach 1:
The patent changes the chemical structure parameters of the polycarbonate resin by specifying terminal group composition (formula 1 with R1-R5 groups) and molecular weight range (18,000-35,000), which modifies the resin's thermal properties and glass-transition temperature to prevent excessive heat exposure to the acrylic layer during thermoforming
Solution Approach 2:
The patent creates a composite material system where the polycarbonate resin and acrylic resin are chemically compatible through specific molecular design, ensuring stable lamination during thermoforming while maintaining surface hardness benefits
2Ease of operation
If the laminated body is thermoformed at high temperature to achieve sufficient elongation, then deep-draw molding capability is improved, but bubbles form due to insufficient drying
Solution Approach 1:
The patent optimizes the polycarbonate resin's molecular weight and terminal group structure to achieve optimal balance between elongation capability and moisture resistance, allowing deep-draw molding at temperatures that do not cause excessive bubble formation
3Ease of manufacture
If a polycarbonate-based resin from polymer alloy is used for lamination, then processability is improved, but lamination failure occurs at the interface due to turbulence
Solution Approach 1:
The patent changes from using polymer alloys to using pure polycarbonate resin with controlled molecular weight and terminal groups, eliminating compositional turbulence at the lamination interface while maintaining adequate processability through molecular design
4Adaptability or versatility
If polycarbonate-based resin from polymer alloy is used, then manufacturing flexibility is improved, but decomposition occurs causing black spots and bumps
Solution Approach 1:
The patent specifies precise molecular weight range (18,000-35,000) and terminal group composition to optimize thermal stability, preventing decomposition and surface defects while maintaining manufacturing flexibility through controlled polymer architecture
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 prevents whitening, cracking, and bubble formation during thermoforming, ensures lamination success, and suppresses defects like black spots and bumps, resulting in a molded article with improved design properties and deep-draw capabilities.
Implementation Method 1
an elongational viscosity of the polycarbonate resin (A) shows a strain softening property at a strain rate of 0.01-5.0/sec
Implementation Method 2
an absolute value of the difference in the glass-transition temperature between the polycarbonate resin (A) and the acrylic resin (B) is within 30°C
Data Source
AI summary
The present invention provides: a new synthetic resin laminated sheet in which whitening, cracking, and foaming do not occur when thermoforming is carried out, in particular when deep-draw molding is carried out, and in which defects similarly do not occur during lamination of a hard coating layer; and a molded article obtained by molding said laminated sheet. Provided is a synthetic resin laminated sheet which has a coating layer, which is configured to include an acrylic resin (B), laminated on one surface of a substrate layer comprising a polycarbonate resin (A) in which a monohydric phenol represented by general formula (1) is used as a chain terminator and which is obtained by reacting said monohydric phenol with a dihydric phenol and a carbonate binding agent and has a viscosity average molecular weight of 18000-35000. (In the formula, R1 represents a C8-36 alkyl group or a C8-36 alkenyl group. R2-R5 each represent hydrogen, halogen, or an optionally substituted C1-20 alkyl group or C6-12 aryl group).