Aliphatic TPU Auto Wrap Films with Patterned Adhesive
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Solution Overview
Problem
Current automotive restyling films, such as PVC and TPU films, face challenges in ease of installation, durability, paint protection, and environmental concerns, particularly with PVC films being difficult to stretch and having high residual stress, and TPU films being highly elastic and requiring water-based installation solutions that can be messy and affect initial tack.
Innovation Solution
Development of thermoplastic films with a thermoplastic polyurethane layer comprising a reaction product of aliphatic diisocyanate, aliphatic polyol, and a chain extending agent, combined with a patterned adhesive layer, which are easier to stretch and install without a slip solution, offering improved rock resistance and elastic recovery while minimizing residual stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PVC films are used for automotive restyling wraps, then the films are easier to apply on complex surfaces, but the high modulus makes them difficult to stretch by a single individual and they provide poor paint protection
Solution Approach 1:
The patent uses TPU as a base material and blends it with PVC in specific ratios (e.g., 20-80% TPU and 80-20% PVC by weight) to create a composite film that combines the stretchability and paint protection of TPU with the ease of application of PVC. This composite structure resolves the contradiction by achieving both operational ease and protective strength simultaneously.
2Strength
If TPU films are used for paint protection, then they provide excellent impact resistance and abrasion resistance, but their high elasticity makes them difficult to work into complex compound surface geometries
Solution Approach 1:
The patent modifies the physical and chemical parameters of TPU by blending it with PVC and adjusting the composition ratios, molecular weight, and processing conditions to reduce the modulus and improve stretchability. This allows the film to be more easily conformable to complex surfaces while retaining adequate impact resistance from the TPU component.
3Ease of operation
If PVC ARW films are made thinner to compensate for higher modulus, then they are easier to stretch, but they do not protect underlying paint as well as TPU films
Solution Approach 1:
The patent creates a composite film where TPU provides the protective strength and PVC provides the ease of stretching. The synergistic combination allows the film to maintain both good paint protection capability and stretchability without needing to be made thinner, thus resolving the contradiction between thickness, protectiveness, and operability.
4Reliability
If chemical adhesion promoters are used at the edges of installed film, then peel adhesion strength is increased and adhesive failure is prevented, but excessive adhesive residue remains on the car after film removal
Solution Approach 1:
The patent develops a self-adhesive TPU-based film that achieves uniform adhesion across the entire film surface through its intrinsic adhesive properties and controlled installation process, eliminating the need for additional chemical adhesion promoters at the edges. This self-service approach provides reliable adhesion without generating harmful adhesive residue.
5Reliability
If heat is applied to the film after installation, then internal stresses are relieved and adhesion failure is prevented, but the installation process becomes more complex and time-consuming
Solution Approach 1:
The patent formulates the TPU-based film with optimized composition and processing parameters that allow it to be installed at lower temperatures and with reduced stretching requirements. The film's modified rheological properties and reduced elastic recovery enable easier installation without requiring post-installation heat treatment, thus simplifying the overall installation process while maintaining reliability.
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 films provide enhanced paint protection, easier installation on complex surfaces, reduced labor costs, and environmental benefits by being halogen-free, with improved load attenuation and tensile properties compared to traditional PVC and TPU films.
Implementation Method 1
the film to stretch more uniformly over a given area of film, by allowing the film to stretch slightly as a squeegee is applied in a lateral direction across the film during installation, which can distribute the residual film stress of the stretched film somewhat uniformly over the length of the film
Implementation Method 2
Another way to mitigate residual internal film stress in ARWs is to apply heat to the film after installation to a sufficiently high temperature to relieve internal stresses so as to prevent adhesion failure between the car and the pressure sensitive adhesive
Data Source
AI summary
Thermoplastic films are disclosed that are suitable for use as auto wraps. The films include a thermoplastic polyurethane layer comprising a thermoplastic polyurethane polymer and a patterned adhesive layer. The thermoplastic films, when tested by a 25% Heat Relaxation Test at a thickness of about 0.006 inches, exhibit a final load from about 0.02 to about 0.3 pounds force; and when tested by a 25% Elastic Recovery test, exhibit a residual strain at one minute of 2% or greater.