Laminated Sheet with Acrylic Copolymer Surface Layer
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Solution Overview
Problem
There is a need for a laminated sheet that is thinner, has excellent shape conformability, and is suitable for affixing to substrates using in-mold injection molding or vacuum thermocompression bonding, while also requiring excellent chemical resistance and scratch resistance, which is difficult to achieve simultaneously.
Innovation Solution
A laminated sheet comprising a surface layer made of a (meth)acrylic copolymer obtained by copolymerizing a monomer blend containing alkyl (meth)acrylate and (meth)acrylic monomers, directly bonded with a heat moldable resin layer, such as an aqueous polyurethane resin, without an additional adhesive layer, to enhance adhesive strength and reduce layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional laminated sheet with multiple layers including adhesive layers is used, then chemical resistance and scratch resistance are improved, but layer thickness increases and shape conformability deteriorates
Solution Approach 1:
The patent combines the adhesive layer and heat moldable resin layer into a single integrated layer. The heat moldable resin layer serves dual functions: providing adhesion to the substrate and enabling shape conformability through thermocompression bonding. This eliminates the need for separate adhesive layers while maintaining bonding strength and reducing overall thickness.
Solution Approach 2:
The patent uses a composite structure where the surface layer contains (meth)acrylic copolymer particles with specific glass transition temperatures, combined with a heat moldable resin layer. This composite material design provides both chemical resistance from the surface layer and shape conformability from the heat moldable resin, achieving multiple functions in a thin configuration.
2Reliability
If a thicker laminated sheet is used to ensure durability, then chemical and scratch resistance are improved, but shape conformability and wrap-in covering ability deteriorate
Solution Approach 1:
The patent controls the glass transition temperature (Tg) of the (meth)acrylic copolymer particles in the surface layer to be 80°C or higher, while the heat moldable resin layer is designed to be soft and flexible at processing temperatures. This parameter optimization allows the surface layer to provide scratch resistance while the heat moldable resin layer enables excellent shape conformability during thermocompression bonding.
Solution Approach 2:
The patent creates different local properties within the laminated sheet: the surface layer has high Tg for durability and scratch resistance, while the heat moldable resin layer has low Tg and high flexibility for shape conformability. Each layer is optimized for its specific function, allowing the thin structure to achieve both durability and conformability.
3Strength
If multiple separate layers including adhesive layers are used, then adhesive strength can be achieved, but manufacturing complexity and production cost increase
Solution Approach 1:
The patent merges the adhesive layer and heat moldable resin layer into a single integrated layer. The heat moldable resin layer inherently provides adhesion through thermocompression bonding, eliminating the need for separate adhesive layers. This simplifies the manufacturing process and reduces production costs while maintaining strong adhesion to the substrate.
4Length of stationary object
If a thin laminated sheet is used to reduce complexity, then layer thickness and manufacturing cost are reduced, but adhesive strength and bonding reliability may deteriorate
Solution Approach 1:
The patent optimizes the glass transition temperature of the heat moldable resin layer to ensure it becomes sufficiently soft at processing temperatures to provide strong adhesion, while remaining thin. The specific Tg range allows the thin layer to achieve excellent bonding strength through thermocompression bonding without requiring multiple thick layers.
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 laminated sheet with high adhesive strength, excellent shape conformability, and improved chemical and scratch resistance, allowing for effective wrap-in covering on substrates without cracking or breaking, at a lower cost than conventional methods.
Implementation Method 1
a surface layer made of a (meth)acrylic copolymer obtained by copolymerizing a monomer blend containing alkyl (meth)acrylate and (meth)acrylic monomers
Implementation Method 2
directly bonded with a heat moldable resin layer, such as an aqueous polyurethane resin, without an additional adhesive layer, to enhance adhesive strength
Implementation Method 3
Another known process for affixing a decorative sheet to a substrate is vacuum thermocompression bonding. In vacuum thermocompression bonding, a decorative sheet is affixed using a pressure difference, while being heated and stretched, on a substrate molded in advance.
Data Source
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AI summary
A laminated sheet includes a surface layer disposed on an outermost surface, a heat moldable resin layer, and an adhesive layer to be adhered to the substrate, the surface layer containing a (meth)acrylic copolymer obtained by copolymerizing a monomer blend containing an alkyl (meth)acrylate having an alkyl group having 1 to 4 carbon atoms and one or more kind of (meth)acrylic monomer expressed by formula (1): CH2=CR1COR2(1) wherein R1 is a hydrogen atom or a methyl group, and R2 is selected from a group including an alkoxy group having 5 or more carbon atoms, a cycloalkoxy group having 5 or more carbon atoms, a hydroxyl group, and a nitrogen-containing group.