pH-Sensitive Topcoat for Recyclable Container Printing
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Solution Overview
Problem
Existing direct printing processes for containers, such as bottles, lack effective recyclability and protection against environmental influences, as the adhesion properties of current methods do not allow for easy detachment and recycling of printed layers.
Innovation Solution
A direct printing method that applies a topcoat to a larger area than the printed layer, which is insoluble in aqueous solutions with a pH between 3 and 10 but soluble at higher temperatures, allowing for easy detachment and improved recyclability, while also protecting the printed layer from environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a permanent printing layer is applied to protect the printed layer from environmental influences, then protection against scratching and environmental factors is improved, but recyclability deteriorates because the permanent layer cannot be detached
Solution Approach 1:
The patent applies a dynamic adhesion concept where the topcoat's bond strength to the substrate changes based on pH conditions. Under neutral pH (3-10), the topcoat maintains strong adhesion for protection, while under extreme pH (>10 or <3), the adhesion weakens to enable detachment for recycling. This dynamic behavior resolves the contradiction between permanent protection and recyclability.
Solution Approach 2:
The invention utilizes pH value as a controlling parameter to switch the adhesion properties of the topcoat. By formulating the topcoat with pH-sensitive adhesion characteristics, the system transitions from a protective state (neutral pH) to a detachable state (extreme pH), enabling both protection during use and easy recycling at end-of-life.
2Strength
If a topcoat is applied to fix the printing ink on the surface, then adhesion and protection are improved, but detachment for recycling becomes difficult
Solution Approach 1:
The topcoat exhibits dynamic adhesion strength that responds to pH changes. At neutral pH values (3-10), the topcoat maintains strong adhesion to fix the printing ink and provide protection. At extreme pH values (>10 or <3), the adhesion strength decreases, allowing easy detachment for recycling purposes.
Solution Approach 2:
The invention employs pH value as a switchable parameter to control adhesion strength. The topcoat is formulated with pH-sensitive binding characteristics, enabling strong ink fixation under normal conditions while allowing controlled detachment under extreme pH conditions during recycling.
3Ease of operation
If a soluble topcoat is used to improve recyclability, then ease of detachment is improved, but protection against environmental influences deteriorates
Solution Approach 1:
The topcoat displays conditional solubility based on pH environment. In neutral pH washing solutions (3-10), the topcoat remains insoluble and provides protective functions. In extreme pH solutions (>10 or <3), the topcoat becomes soluble and detaches, enabling recycling. This conditional behavior resolves the contradiction between protection and recyclability.
Solution Approach 2:
The invention utilizes pH value as a controlling parameter for solubility. The topcoat is designed with pH-dependent solubility characteristics, remaining stable and protective under neutral conditions while dissolving under extreme pH conditions during the recycling process.
4Object-affected harmful factors
If the topcoat area is larger than the printed layer area, then coverage and protection are improved, but material consumption increases
Solution Approach 1:
The patent applies local quality by extending the topcoat coverage beyond the printed layer boundaries. The topcoat is applied to a second defined area that encompasses the first defined area (printed layer) and provides additional protective margins. This ensures comprehensive protection of the printed areas while allowing selective detachment during recycling.
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 method enhances recyclability and environmental protection by ensuring the topcoat can be dissolved in common washing solutions, allowing for easy removal of the printed layer, reducing material costs, and providing additional properties like optical and hardness enhancements through irradiation.
Implementation Method 1
the cover layer forming a second connection with the container in parts of the second defined area different from the first defined area, the first and second connections being insoluble in aqueous solutions having a pH between 3 and 10 and good soluble in aqueous solutions with a pH in a range less than 3 and/or greater than 10
Implementation Method 2
This top layer on the one hand fixes the printing ink on the surface of the container without having to adhere strongly to it and on the other hand protects the printing layer from environmental influences, such as scratching or the like
Implementation Method 3
the second device (102) is suitable for applying the cover layer in the second specific area, the second specific area covering the first specific area and the second specific range is greater than the first specific range
Data Source
AI summary
Direct printing method for printing on containers such as bottles (130) using a direct printing machine (100), wherein, in a first step, the container is printed with a printing layer in a first device (101) at least in a first definite area, and, in a second step, a top layer is applied to the container in a second device (102), wherein the top layer is applied to a second definite area that includes the first definite area and whose area is larger than that of the first definite area, wherein the top layer forms a first bond with the printing ink in the first definite area, and wherein the top layer forms a second bond with the container in parts of the second definite area that are different from the first definite area.wherein the first and second compounds are insoluble in aqueous solutions with a pH between 3 and 10 and readily soluble in aqueous solutions with a pH in a range less than 3 and/or greater than 10.