Stretchable Film Composite Structure for Wearable Device Adhesion
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Solution Overview
Problem
Existing stretchable films face challenges in achieving a balance between stretchability, strength, and water repellency, often resulting in surface stickiness issues that hinder printing and adhesion of ink, particularly in wearable devices where conductive wiring is involved.
Innovation Solution
A stretchable film comprising a silicone main-chain type urethane layer and a silicone-pendant type urethane layer, with specific structural formulas, is developed to enhance stretchability, strength, and water repellency, while minimizing surface stickiness, allowing for effective use in wearable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyurethane film is used to achieve high stretchability and strength, then the film surface becomes sticky causing difficulty in separation and printing, but if a silicone film is used to achieve high release characteristics and water repellency, then the strength becomes low causing easy breakage
Solution Approach 1:
The invention uses a composite material consisting of polyurethane as the base polymer and silicone grafts as functional modifiers. The polyurethane provides the mechanical strength and stretchability, while the silicone grafts provide water repellency and reduce surface stickiness. This composite structure allows simultaneous achievement of high strength and low surface energy characteristics that were previously mutually exclusive.
Solution Approach 2:
The invention applies local quality by modifying only the surface regions of the polyurethane chains with silicone grafts. The bulk polyurethane structure maintains its high strength and elasticity, while the grafted silicone groups on the surface provide the desired low surface energy and water repellency. This localized modification allows different regions of the material to have different properties.
2Object-generated harmful factors
If a polyurethane film with silicone pendant is used to achieve balanced stretchability and strength, then the film surface sticks to itself and printing plates, but if the silicone content is increased to reduce stickiness, then the strength and adhesion to ink decrease
Solution Approach 1:
The invention changes the chemical parameters by controlling the degree of graft substitution and the length of silicone side chains. By optimizing these parameters, the film achieves sufficient surface stickiness reduction for printing while maintaining adequate strength and ink adhesion. The specific parameter range creates a balance point where harmful stickiness is minimized but not at the expense of mechanical properties.
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 film achieves excellent stretchability and strength comparable to polyurethane, with improved water repellency and reduced surface tackiness, making it suitable for applications in wearable devices and conductive wiring without sticking issues.
Implementation Method 1
The urethane film has high stretchability and strength
Implementation Method 2
cured products of the silicone urethane polymer are characterized by higher strength than single silicone and lower hydrolysis than single polyurethane
Implementation Method 3
silicone films have high release characteristics and are prevented from sticking with each other thereby
Implementation Method 4
the hydrolysis inherent in the urethane film lowers its stretchability and strength
Data Source
AI summary
The present invention is a stretchable film including: a silicone main-chain type urethane layer and a silicone-pendant type urethane layer, wherein the silicone main-chain type urethane layer has a structure shown by the following general formula (1)-1 and/or (1)-2 and is formed on the silicone-pendant type urethane layer, and the silicone-pendant type urethane layer has a structure shown by the following general formula (2)-1 and/or (2)-2. The present invention provides a stretchable film having excellent stretchability and strength, with the film surface having excellent water repellency, together with a method for forming the same.