In-Line Coated BOPP Antistatic Films
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Solution Overview
Problem
Current methods for producing antistatic polyolefin films, particularly polypropylene-based films, fail to achieve long-lasting antistatic, antiblocking, slipperness, and improved wetting tension properties, especially when biaxially oriented and multilayered, due to hydrophobic surfaces that hinder the formation of polar monomer coatings without preliminary treatments.
Innovation Solution
A multilayered structure with a thin antistatic skin layer containing crosslinkable copolymers and ionic antistatic agents based on complexed binary systems, such as poly(ethylene imine) and acrylic copolymers, combined with inner and core layers of polypropylene and masterbatches, is developed for in-line coating, enhancing antistatic properties through hydrogen bonding interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If preliminary surface treatments (corona, plasma, flame, chemical) are applied to polyolefin films to enable polar monomer coating, then adhesion and wetting tension improve, but process complexity and production time increase
Solution Approach 1:
The patent applies preliminary corona treatment to the polyolefin film surface before coating to increase surface energy and enable polar monomer adhesion. This preliminary action modifies the hydrophobic surface to accept the polar coating without requiring more complex chemical treatments.
Solution Approach 2:
The patent uses a primer layer as an intermediary between the polyolefin substrate and the polar monomer coating. The primer contains both polar and non-polar components that bridge the hydrophobic-polar interface, enabling adhesion without extensive surface treatment.
2Reliability
If conventional offline coating methods are used with organic antistatic additives, then antistatic properties are achieved, but production time increases and environmental concerns arise
Solution Approach 1:
The patent combines the coating operation with the film production line, applying the antistatic coating in-line immediately after extrusion while the film is still warm and pliable. This merges two separate processes (film production and coating) into one continuous operation, eliminating downtime.
Solution Approach 2:
The patent replaces conventional offline mechanical coating methods with an in-line spray coating system that applies coating material during the film production process. This substitution eliminates the need for separate coating equipment and handling steps.
3Ease of manufacture
If polar monomer coatings are applied to hydrophobic polyolefin surfaces without treatment, then coating simplicity is maintained, but adhesion and antistatic durability deteriorate
Solution Approach 1:
The patent changes the surface energy parameters of the polyolefin film through corona treatment, transforming the hydrophobic surface into a state that can accept polar monomer coatings. This parameter change enables direct coating without compromising adhesion.
Solution Approach 2:
The patent creates a composite structure with multiple layers: the polyolefin substrate, a primer layer with mixed polar/non-polar characteristics, and a polar monomer coating layer. This composite approach ensures compatibility between hydrophobic and polar components while maintaining durability.
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 solution provides polypropylene films with improved antistatic, antiblocking, and wetting tension properties that are maintained over time, suitable for various packaging applications, including food and agriculture, while being compatible with different lamination adhesives.
Implementation Method 1
enhancing antistatic properties through hydrogen bonding interactions
Implementation Method 2
ionic antistatic agents based on complexed binary systems such as poly(ethylene imine) and acrylic copolymers
Data Source
Figure 1
Figure 2(I)~2(V)
AI summary
The invention relates to an acrylic/maleic based antistatic in-line coated multilayered biaxially oriented polypropylene (BOPP) based film comprising: " a skin layer comprising a polypropylene or the mixture of polypropylene with copolymer or terpolymer and in-line surface coated thin antistatic layer; " two inner layers between the skin layer and the core layers and between the core and the outer layers, comprising a polypropylene or the mixture of polypropylene with copolymer or terpolymer, " a core layer between two said inner layers, comprising polypropylene, " a treated outer layer comprising a polypropylene or copolymer or terpolymer, The disclosure also includes the process for producing inline coated BOPP films wherein in-line coating system is revised, improved and integrated into standard flat tenter biaxially oriented polypropylene processing and manufacturing line.