Aqueous Inkjet Ink Adhesion to Plastic Films via Chlorinated Polypropylene Primer
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Solution Overview
Problem
Aqueous inkjet ink compositions have poor adhesion to plastic films, leading to separation issues during food packaging, transportation, and display, particularly with oriented polypropylene (OPP) films, which complicates the printing process for flexible packaging containers with decreasing lot sizes and increasing product variety.
Innovation Solution
An aqueous inkjet ink composition containing a polyurethane resin derived from specific reaction components, combined with a primer composition containing chlorinated polypropylene, provides excellent adhesion to various base films, including OPP, PET, and nylon, ensuring strong laminate and seal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aqueous inkjet ink composition is used for printing on plastic films, then environmental safety and residual solvent reduction are improved, but adhesion to plastic films deteriorates
Solution Approach 1:
A primer composition containing chlorinated polypropylene is applied to the plastic film surface before inkjet printing. This primer acts as an intermediary layer that enhances the adhesion between the aqueous inkjet ink and the non-polar plastic film surface, particularly effective for OPP films. The primer composition includes chlorinated polypropylene (1-10 parts by mass), polyethylene glycol (5-50 parts by mass), and water (40-80 parts by mass), creating a surface that is more compatible with aqueous inks while maintaining environmental benefits.
2Manufacturing precision
If gravure printing is used to achieve excellent printed image quality, then printing quality is improved, but manufacturing cost and production time increase due to expensive and time-consuming printing plate production
Solution Approach 1:
The invention replaces the physical printing plate copying process with direct digital inkjet printing. Instead of creating expensive metal printing plates through chemical corrosion, mechanical engraving, or laser engraving followed by chromium plating, the system uses aqueous inkjet ink to directly deposit images and text onto the plastic film. This digital copying approach eliminates plate production costs and allows for rapid design changes without remanufacturing costs.
3Productivity
If gravure printing with fixed printing plates is used, then large quantity production is economical, but adaptability to decreasing lot size and increasing product variety deteriorates
Solution Approach 1:
The printing system transitions from static printing plates to dynamic digital inkjet printing. The inkjet printing system can rapidly change printing content, designs, and specifications without physical plate changes. This dynamic capability allows the same equipment to efficiently produce small batches of diverse products by simply updating the digital printing data, making the system adaptable to decreasing lot sizes and increasing product variety in flexible packaging.
4Illumination intensity
If white ink printing is performed to achieve high light-shielding properties and contrast, then optical properties are improved, but the complexity of the printing process increases
Solution Approach 1:
The invention utilizes the inherent white color of the plastic film base material by printing only the colored portions of the design. By controlling the inkjet printing parameters to deposit ink only where needed, the system maintains the white background's light-shielding properties and contrast without requiring a separate white ink printing step. This parameter control approach simplifies the printing process while achieving the desired optical properties.
Data Source
AI summary
The present invention aims to provide an aqueous inkjet ink composition for lamination that can provide various advantages such as reduction of residual solvent, improvement of the printing work environment, prevention of air pollution, and fire safety, enables efficient adaptation to the recent decrease in lot size and increase in product variety, has high versatility that allows use for various types of base film, and enables production of a food packaging container that does not break at least during processes such as transportation and display and can be easily opened without causing the double bag state. The aqueous inkjet ink composition for lamination of the present invention contains a colorant, an alkali-soluble or self-emulsifying aqueous polyurethane resin satisfying the following condition 1, and an aqueous medium: Condition 1: the alkali-soluble or self-emulsifying aqueous polyurethane resin is a reaction product of reaction components including hexamethylene diisocyanate, at least one selected from the group of polyester diol compounds represented by the following formula 1, and an acid group-containing diol compound: wherein Xs are each independently a hydrocarbon group represented by -CH2-CH2-CH2-CH2-CH2-CH2- or -CH2-CH2-CH(CH3)-CH2-CH2-, and n is an integer of 2 to 20.