Polyurethane Lamination Adhesive for Electro-Optic Displays
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Solution Overview
Problem
Existing lamination adhesives for electro-optic displays have insufficient adhesive properties and are too rigid, leading to poor lamination quality and defects such as voids, and they crystallize at high temperatures, affecting the electro-optic properties of the displays.
Innovation Solution
A polyurethane lamination adhesive is developed with a specific molecular structure, comprising an isocyanate, a polyether diol, and a polyester diol with steric hindrance groups, which reduces rigidity and improves adhesive properties, allowing it to be coated directly on dried electrophoretic layers, thus enhancing the manufacturing process and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing lamination adhesives are used, then the adhesive provides basic bonding, but the adhesive is too rigid and crystallizes at high temperatures, leading to poor lamination quality and defects
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive by incorporating specific plasticizers (adipates, phosphates, carboxylic acid salts) in controlled amounts (0.1-10% by weight) to change the physical properties of the adhesive, reducing its rigidity and preventing crystallization while maintaining bonding strength
Solution Approach 2:
The patent creates a composite adhesive system combining multiple components: base adhesive resin, plasticizers, and stabilizers working together to achieve the desired balance between flexibility, adhesion, and thermal stability, preventing the harmful crystallization effect
2Manufacturing precision
If the adhesive is made less rigid to improve lamination quality, then lamination defects are reduced, but the adhesive strength may decrease
Solution Approach 1:
The patent carefully controls the concentration of plasticizing agents within specific ranges (0.1-10% by weight) to optimize the balance between flexibility and bonding strength, ensuring that the adhesive remains strong enough for lamination while being flexible enough to prevent defects
Solution Approach 2:
The patent introduces plasticizers as intermediary substances that mediate between the rigid adhesive resin and the substrate, allowing the adhesive to conform to surface irregularities and distribute stress evenly, thereby preventing lamination defects while maintaining bonding integrity
3Stability of the object's composition
If the adhesive crystallizes at high temperatures, then the adhesive maintains structural integrity, but the electro-optic properties of the display are affected
Solution Approach 1:
The patent converts the potentially harmful crystallization effect into a beneficial outcome by using plasticizers to suppress crystallization and prevent the formation of rigid crystal structures that would harm electro-optic properties, while the plasticized adhesive maintains structural integrity through flexible molecular networks
Solution Approach 2:
The patent changes the thermal behavior parameters of the adhesive by incorporating plasticizers that lower the glass transition temperature and suppress crystallization, allowing the adhesive to remain in a flexible amorphous state at operating temperatures, thereby preserving electro-optic properties while maintaining structural stability
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 new adhesive provides improved lamination quality, reduces crystallization transitions, and maintains electro-optic properties over time, ensuring stable and efficient production of electro-optic displays.
Implementation Method 1
a layer of polyurethane lamination adhesive adhered to the layer of electro-optic material
Data Source
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AI summary
A polyurethane is formed from an isocyanate, a polyether diol and a polyester diol, the polyester diol having a molecular weight less than about 2000, or comprising two polyester diol segments connected by a steric hindrance group, each of the polyester diol segments having a molecular weight less than about 2000, the molar ratio of polyether diol to polyester diol being in the range of from about 1:9 to about 9:1. The polyurethane is useful as a lamination adhesive in electro-optic displays, and in components used to form such displays.