UV Curable Adhesive Film with Glass Bubbles for Cohesive Failure
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Solution Overview
Problem
Current adhesive tapes and films face challenges in achieving high bonding strength, odorlessness, and cohesive failure mode, making them unsuitable for modern design requirements in household and automotive applications, particularly due to weak bonding strength of pressure-sensitive adhesives and strong odors from foam tapes, as well as complex and costly manufacturing processes of fiber-reinforced adhesive tapes.
Innovation Solution
A UV curable composition comprising 25-60 wt% ethylene-vinyl acetate copolymer, 20-60 wt% epoxy resin, 5-20 wt% glass bubbles, and 0.3-8 wt% hydroxy-containing compound, with glass bubbles meeting specific density and collapse pressure conditions, which allows for cohesive failure and low odor, suitable for bonding plastics and metals without high-temperature curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pressure sensitive adhesive tapes are used for bonding, then bonding can be achieved by applying small amounts of pressure for a short duration without high-temperature curing, but the bonding strength is weak and generally does not exceed 1 MPa
Solution Approach 1:
The patent changes the bonding mechanism from mechanical adhesion (pressure-sensitive) to photochemical curing (UV-curable). The adhesive composition includes photoinitiators that trigger polymerization upon UV exposure, transforming the bonding process from pressure-dependent to light-dependent, thereby achieving high bonding strength while maintaining operational simplicity
Solution Approach 2:
The adhesive tape employs a composite structure combining a pressure-sensitive adhesive layer with a UV-curable adhesive layer. This composite design allows the tape to exhibit both immediate pressure-sensitive bonding capability and high-strength cured bonding properties, resolving the contradiction between ease of operation and bonding strength
2Strength
If foam adhesive tapes are used for bonding, then bonding strength is higher than pressure sensitive adhesives, but strong odors are produced making them unsuitable for household appliances or automobiles
Solution Approach 1:
The patent changes the chemical composition and curing mechanism of the adhesive from foam-based (solvent-evaporating) to UV-curable polymerization. This parameter change eliminates the need for solvent evaporation, thereby eliminating strong odors while maintaining high bonding strength through photochemical crosslinking
Solution Approach 2:
The patent replaces the mechanical/chemical bonding mechanism of foam adhesives (which rely on solvent evaporation and foam expansion) with a photochemical bonding mechanism. UV light initiates polymerization reactions that create strong bonds without producing harmful odors, thus substituting a harmful chemical process with a cleaner physical-chemical process
3Strength
If fiber-reinforced single-layer structure adhesive tape is used to achieve desirable shape retention and bonding strength, then the bonding strength improves, but the manufacturing process becomes significantly more complex and costs increase
Solution Approach 1:
The patent creates a composite adhesive system by combining pressure-sensitive and UV-curable adhesive layers in a single tape structure. This composite approach achieves high bonding strength and shape retention through the UV-curable layer's crosslinked network, while avoiding the need for separate fiber reinforcement layers and complex vacuum hot pressing processes
Solution Approach 2:
The patent extracts and eliminates the complex fiber reinforcement and vacuum hot pressing steps from the manufacturing process. By incorporating UV-curable adhesive with inherent structural properties, the patent removes the need for additional reinforcing layers and complex curing equipment, thereby simplifying the manufacturing process while maintaining bonding strength
4Reliability
If adhesive films or tapes are designed for high bonding strength, then bonding reliability improves, but cohesive failure mode and overflow problems occur
Solution Approach 1:
The patent applies local quality by creating distinct adhesive layers with different properties: the pressure-sensitive layer provides initial bonding and the UV-curable layer provides structural strength. This localized functional differentiation allows the adhesive to achieve high bonding reliability while maintaining cohesive failure mode through proper layer design and composition
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 UV curable adhesive film exhibits initial adhesivity, semi-structural to structural strength after curing, and low odor, suitable for bonding in internal components of household appliances, automobiles, and electronic products, with improved bonding reliability and stability.
Implementation Method 1
UV curable composition comprising ethylene-vinyl acetate copolymer, epoxy resin, glass bubbles, hydroxy-containing compound, and photoinitiator
Data Source
AI summary
The present invention provides a UV curable composition, a UV curable adhesive film and a UV curable adhesive tape. The UV curable composition comprises, based on the total weight thereof as 100 wt%: 25 to 60 wt% of an ethylene-vinyl acetate copolymer; 20 to 60 wt% of an epoxy resin; 5 to 20 wt% of glass bubbles; 0.3 to 8 wt% of a hydroxy-containing compound; and 0.5 to 5 wt% of a photoinitiator. According to the technical solution of the present invention, cohesive failure can be achieved in the cured adhesive film by the addition of glass bubbles into the UV curable system. The UV curable product provided in the present invention can achieve a good balance among the initial adhesivity, structural strength after curing, odorlessness or low odor, and other performance.