Multi-layer adhesive film with heat curable and tacky layers
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Solution Overview
Problem
Existing multi-layer adhesive films fail to effectively maintain substrates in a fixed position at room temperature and lack the ability to form strong, permanent bonds between substrates without the need for additional heat, while also preventing movement during assembly and shipment.
Innovation Solution
A multi-layer adhesive film featuring a heat curable adhesive film with a tacky adhesive composition on one or both surfaces, comprising polyurethane and surface-deactivated solid isocyanate, which can be activated by heat to form a strong bond, allowing for temporary or permanent attachment of substrates without additional heat for maintaining position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a heat curable adhesive film is used, then strong permanent bonds can be formed between substrates, but the substrates cannot be maintained in a fixed position at room temperature
Solution Approach 1:
The adhesive system is divided into two distinct functional layers: a heat curable adhesive film providing strong permanent bonds, and a separate tacky adhesive composition providing immediate room temperature positioning. This segmentation allows each layer to perform its specialized function without compromise.
Solution Approach 2:
The invention creates a composite adhesive system by combining the heat curable adhesive film with a tacky adhesive composition comprising polyurethane and surface-deactivated solid isocyanate. This composite structure integrates the complementary properties of both materials: the heat-activated bonding capability and the room temperature tackiness.
2Reliability
If additional heat is applied to maintain substrate position, then position stability is improved, but the process complexity and energy consumption increase
Solution Approach 1:
The tacky adhesive composition is formulated to maintain its tacky properties at room temperature through specific compositional parameters (polyurethane with surface-deactivated solid isocyanate at controlled coat weights). This eliminates the need for thermal parameter changes to achieve positioning, allowing cold bonding capability.
3Reliability
If the adhesive composition is made tacky at room temperature, then substrates can be positioned without heat, but the bond strength and permanence are reduced
Solution Approach 1:
The tacky adhesive composition performs the preliminary action of bonding substrates at room temperature to establish fixed positioning. Subsequently, heat is applied to activate the heat curable adhesive film, which then cures to provide the strong permanent bond. This sequential action ensures both positioning and ultimate bond strength are achieved.
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 multi-layer adhesive film achieves a cured 180° peel strength of at least 10 N/25 mm and can maintain substrates in a fixed position at room temperature, forming strong, permanent bonds between substrates, reducing movement during assembly and shipment processes.
Implementation Method 1
heating the multi-layer adhesive film to a temperature sufficient to activate the cure of the multi-layer adhesive film
Implementation Method 2
the first tacky adhesive composition being tacky at room temperature
Data Source
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AI summary
Disclosed is a multi-layer adhesive film including a heat curable adhesive film and a first tacky adhesive composition disposed on the first major surface of the heat curable adhesive film. The heat curable adhesive film includes a surface-deactivated solid isocyanate and a polyurethane that includes functional groups that are reactive with isocyanate. A method of making an article that includes the multi-layer adhesive film and article made thereby are also disclosed.