Solvent-less Adhesive Laminate Process for BOPP Films
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Solution Overview
Problem
Traditional laminates using solvent-based adhesives for BOPP film layers require an additional drying step, leading to insufficient adhesion and potential defects like telescoping, tunneling, and air gaps due to the time needed for solvent evaporation and curing, which increases processing costs and equipment requirements.
Innovation Solution
A process involving at least 6 pearlized biaxially oriented polypropylene (BOPP) film layers with a solvent-less adhesive composed of a polyol component, such as polyester or polyether polyol, and an isocyanate component, including an isocyanate prepolymer, applied at a coat weight of 2.0 g/m2 to 3.5 g/m2 between each film layer, eliminating the need for oven drying and allowing for immediate adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solvent-based adhesive is used for bonding BOPP film layers, then adhesion can be achieved, but additional drying equipment and processing steps are required, increasing device complexity and processing costs
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive by using a water-based adhesive system instead of solvent-based adhesive. This parameter change eliminates the need for drying equipment and processing steps while maintaining adhesion between BOPP film layers, directly resolving the technical contradiction between achieving adhesion and reducing device complexity
2Strength
If solvent-based adhesive is used, then bonding can occur, but insufficient adhesion develops within minutes to hours after application, leading to laminate defects
Solution Approach 1:
The invention changes the chemical parameters of the adhesive system by using a water-based adhesive with specific polyol and isocyanate components. This enables the adhesive to achieve sufficient bond strength within minutes to hours, preventing laminate defects such as telescoping, tunneling, and air gaps, thereby resolving the contradiction between adhesion strength and adhesion reliability
3Strength
If solvent-based adhesive requiring drying step is used, then adhesion can be formed, but processing time and costs increase
Solution Approach 1:
The invention changes the adhesive system parameters from solvent-based to water-based formulation. This eliminates the drying step entirely, allowing the adhesive to become tacky and form bonds within minutes to hours, thereby increasing processing speed and efficiency while maintaining adhesion quality
Solution Approach 2:
The water-based adhesive is formulated to become tacky quickly after application, performing the bonding action preliminarily within minutes to hours without requiring subsequent drying. This preliminary bonding action eliminates the need for separate drying steps, improving productivity
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 solvent-less adhesive ensures sufficient adhesion between BOPP film layers within minutes to hours, preventing defects and reducing processing costs by eliminating the need for additional drying steps, while maintaining a bond strength of at least 300 g/15 mm and tear forces suitable for applications like billboards and wall signs.
Implementation Method 1
The solvent-less adhesive contains (i) a polyol component including at least one polyol selected from a polyester polyol, a polyether polyol, and combinations thereof; and (ii) an isocyanate component including an isocyanate prepolymer that is the reaction product of at least one isocyanate monomer and at least one polyol selected from a polyester polyol, a polyether polyol, and combinations thereof
Data Source
AI summary
The present disclosure provides a process. The process includes (A) providing at least 6 film layers, each film layer being a pearlized biaxially oriented polypropylene; (B) applying a solvent-less adhesive at a coat weight of 2.0 g/m2 to 3.5 g/m2 between each film layer; and (C) forming a laminate, the laminate having a thickness of at least 300 μm. The solvent-less adhesive contains (i) a polyol component including at least one polyol selected from a polyester polyol, a polyether polyol, and combinations thereof; and (ii) an isocyanate component including an isocyanate prepolymer that is the reaction product of at least one isocyanate monomer and at least one polyol selected from a polyester polyol, a polyether polyol, and combinations thereof. The present disclosure also provides a laminate formed by said process.