Polyurethane Thermal Adhesive Layer for Decorative Film
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing decorative films struggle to achieve sufficient adhesion to articles made of polycarbonate (PC) or acrylonitrile/butadiene/styrene copolymer (ABS) without primer treatment, especially during heat expansion processes like insert molding (IM) and three-dimensional overlay method (TOM), due to inadequate heating and surface temperature issues.
Innovation Solution
A decorative film with a polyurethane thermal adhesive layer containing thermoplastic polyurethanes, such as polyester-based or polycarbonate-based polyurethanes, which provides excellent adhesion by maintaining a fracture strength of at least 1 MPa at 135°C and suitable storage modulus and coefficient of loss, allowing for effective heat expansion and surface coverage without primer treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a decorative film is applied to PC or ABS articles using conventional adhesive layers, then the film can be applied to three-dimensional surfaces, but sufficient adhesion is not achieved without primer treatment
Solution Approach 1:
The adhesive layer uses a polymer blend with specific glass transition temperatures (component A: Tg ≤ 25°C, component B: Tg ≥ 75°C) and controlled composition ratios to achieve sufficient adhesion to PC and ABS without primer treatment. The parameter optimization of polymer properties enables direct application while maintaining reliable bonding.
2Shape
If the film is heated and stretched to conform to three-dimensional article surfaces, then the film can cover complex shapes, but peeling occurs due to film contraction at temperatures exceeding 100°C
Solution Approach 1:
The adhesive layer dynamically adapts its mechanical properties with temperature: at application temperature it provides flexibility for conforming to three-dimensional surfaces, while at service temperatures it maintains sufficient strength to prevent peeling. The polymer blend achieves this dynamic behavior through its specific glass transition temperature range and composition.
3Reliability
If primer treatment is applied to achieve sufficient adhesion, then adhesion improves, but the process complexity and time increase
Solution Approach 1:
The invention extracts and eliminates the primer treatment step from the conventional adhesive application process. By incorporating specific polymer components directly into the adhesive layer formulation, the system achieves sufficient adhesion to PC and ABS without requiring the separate primer application step, thereby reducing process complexity and application time.
4Shape
If the adhesive layer is heated to high temperatures for film application, then the film conforms to the surface, but the adhesive strength decreases due to thermal effects
Solution Approach 1:
The adhesive layer employs a composite polymer system combining two distinct (meth)acrylic polymer components with complementary properties. This composite structure enables the adhesive to withstand the thermal effects of heating during application while maintaining sufficient bonding strength, as each polymer component contributes different thermal and adhesive characteristics that work synergistically.
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 adhesive strength to PC or ABS materials during heat expansion processes, ensuring reliable adhesion and integration without the need for primer treatment, enhancing the durability and applicability of decorative films in complex shapes.
Implementation Method 1
contains a thermoplastic polyurethane selected from the group consisting of polyester-based polyurethanes and polycarbonate-based polyurethanes
Implementation Method 2
capable of covering an article having a three-dimensional shape by heat expansion
Data Source
Figure 1~4
Figure 5
Figure 6A~6E
AI summary
A film capable of covering an article having a three-dimensional shape by heat expansion provided by one embodiment of the present disclosure comprises an outermost layer disposed on an outermost surface, and a polyurethane thermal adhesive layer, which contains a thermoplastic polyurethane selected from the group consisting of polyester-based polyurethanes and polycarbonate-based polyurethanes and is thermally adhered to the article during the heat expansion, wherein the fracture strength of the polyurethane thermal adhesive layer is not less than 1 MPa at 135°C, and the storage modulus at 150°C and frequency 1.0 Hz is from 5 x 103 Pa to 5 x 105 Pa, and the coefficient of loss tanδ is not less than 0.1.