Laminated Sheet with Carbodiimide Crosslinked Adsorbing Layer
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Solution Overview
Problem
The existing self-adsorbing sheets face challenges in achieving a balance between proper self-adsorption, low formaldehyde emission, and easy release from adherends, with previous solutions either compromising on smoothness or making removal difficult due to increased self-adsorption strength.
Innovation Solution
A laminated sheet comprising a synthetic paper layer, an adsorbing layer made from a (meth)acrylic acid ester copolymer resin with a carbodiimide crosslinking agent, and a release sheet layer with specific surface roughness and tensile elastic moduli, ensuring balanced properties and easy release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a melamine crosslinking agent is used to enhance various strengths, then cohesive force is improved, but formaldehyde emission increases significantly
Solution Approach 1:
The patent changes the chemical parameter of the crosslinking agent from melamine (formaldehyde-based) to carbodiimide (formaldehyde-free), thereby maintaining crosslinking functionality while eliminating formaldehyde emission. This parameter substitution resolves the contradiction between strength enhancement and harmful emission.
Solution Approach 2:
The patent converts the harmful formaldehyde crosslinking mechanism into a beneficial carbodiimide crosslinking mechanism that provides similar or enhanced cohesive force without the harmful byproduct. The carbodiimide group reacts with hydroxyl groups to form stable crosslinks, turning a potentially harmful chemical process into a clean, beneficial one.
2Object-generated harmful factors
If a carbodiimide crosslinking agent is used to reduce formaldehyde emission, then formaldehyde emission is reduced, but self-adsorption strength increases making removal difficult
Solution Approach 1:
The patent adjusts the gel fraction parameter of the (meth)acrylic acid ester copolymer to a specific range (30-70%) to modulate the self-adsorption strength. By controlling this parameter, the patent achieves optimal balance between sufficient self-adsorption for functionality and manageable strength for easy removal, resolving the contradiction with carbodiimide crosslinking.
3Strength
If the gel fraction of (meth)acrylic acid ester copolymer is increased to achieve proper self-adsorption, then self-adsorption is improved, but smoothness of the foamed resin layer deteriorates
Solution Approach 1:
The patent optimizes the gel fraction parameter to a specific range (30-70%) rather than maximizing it, and combines this with carbodiimide crosslinking to achieve the desired self-adsorption. This controlled parameter adjustment, together with the alternative crosslinking mechanism, prevents excessive gelation that would ruin smoothness while maintaining adequate self-adsorption.
Solution Approach 2:
The patent creates a composite system combining (meth)acrylic acid ester copolymer with controlled gel fraction and carbodiimide crosslinking agent. This composite approach allows the benefits of both components: the copolymer provides the base structure with controlled gel fraction for smoothness, while the carbodiimide crosslinking enhances self-adsorption without compromising smoothness.
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 extremely low formaldehyde emission, proper self-adsorption, and easy release, maintaining smoothness and mechanical strength while allowing for easy separation of the release sheet from the adsorbing layer.
Implementation Method 1
a crosslinking agent is often used together in this foamed resin layer for the purpose of improving a cohesive force and enhancing various strengths
Implementation Method 2
the gel fraction of the (meth)acrylic acid ester copolymer has to be increased in order to obtain proper self-adsorption
Implementation Method 3
A mechanism for sticking of the self-adsorbing sheet owes much more to adsorption to an adherend utilizing microcavities as suction cups
Implementation Method 4
a release sheet layer with specific surface roughness and tensile elastic moduli, ensuring balanced properties and easy release
Data Source
Figure 1
AI summary
Provided is a laminated sheet including an upper paper layer and a release sheet layer, the upper paper layer including synthetic paper and an adsorbing layer, the synthetic paper, the adsorbing layer and the release sheet layer, in order, being laminated, wherein the adsorbing layer is a foam sheet of a resin composition, the resin composition containing crosslinking resultant of 100 parts by mass of a (meth)acrylic acid ester copolymer resin and 1 to 20 parts by mass of a carbodiimide crosslinking agent, the (meth)acrylic acid ester copolymer resin having a N-methylol group, a glass transition temperature of the (meth)acrylic acid ester copolymer resin being no more than -10°C, the release sheet layer consists of a thermoplastic resin sheet, and a rate of tensile elastic moduli is 0.1 to 10, the rate being calculated from a tensile elastic modulus of the upper paper layer and a tensile elastic modulus of the release sheet layer, and a peel strength of the adsorbing layer and the release sheet layer is 5 to 30 N/m, the laminated sheet using a new foamed resin layer having well-balanced properties, the amount of formaldehyde emitted from which is extremely small, as the adsorbing layer, the release sheet and the adsorbing layer having a proper release force.