Metal Printing Ink Composition for Transferability and Varnish Compatibility
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Solution Overview
Problem
Existing metal printing ink compositions face issues with compatibility with aqueous overprint varnishes, leading to repelling and deterioration in glossiness and adhesion, and require high oil length for transferability, which worsens compatibility.
Innovation Solution
Incorporating a rosin-modified resin with a hydroxyl value of 10 mg KOH/g or greater and a polyoxyalkylene alkyl ether-based solvent, along with hydrophilic silica particles, to enhance compatibility and transferability without increasing the oil length of the alkyd resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the oil length of an alkyd resin is increased to improve transferability during printing, then transferability is improved, but compatibility with aqueous overprint varnishes deteriorates causing repelling
Solution Approach 1:
The invention changes the chemical parameters of the resin system by introducing a rosin-modified resin with specific hydroxyl value (5-50 mg KOH/g) and acid value (50-150 mg KOH/g), and controlling the oil length of alkyd resin within a specific range (20-40%). This parameter optimization allows achieving both good transferability and compatibility with aqueous overprint varnishes without the need to excessively increase oil length
Solution Approach 2:
The invention uses a composite resin system combining rosin-modified resin and alkyd resin in specific proportions (rosin-modified resin: 10-50 parts, alkyd resin: 50-90 parts by mass). This composite approach leverages the complementary properties of both resins to achieve both transferability and varnish compatibility simultaneously
2Reliability
If polyoxyalkylene alkyl ether-based solvents are used to improve compatibility with aqueous overprint varnishes, then compatibility is improved, but fluidity of the ink composition deteriorates
Solution Approach 1:
The invention optimizes the molecular structure parameters of the polyoxyalkylene alkyl ether solvent by controlling the alkylene group carbon number (2-4 carbons), alkyl group carbon number (1-13 carbons), and polyether chain length (n=2-8). This parameter optimization balances the solvent's polarity and molecular size to achieve both good compatibility with aqueous varnishes and adequate ink fluidity
Solution Approach 2:
The invention introduces hydrophilic silica particles (1-10 parts by mass) as a local modification to the ink system. These particles improve the overall fluidity and printing characteristics of the ink composition, compensating for the reduced fluidity caused by using polyoxyalkylene alkyl ether solvents
3Ease of operation
If low-polarity solvents such as high-boiling-point aromatic hydrocarbons are used to improve fluidity and reduce misting, then fluidity is improved, but repelling with aqueous overprint varnishes occurs
Solution Approach 1:
The invention changes the polarity parameter of the solvent system by selecting polyoxyalkylene alkyl ether solvents with specific molecular characteristics (alkylene group with 2-4 carbons, polyether chain with n=2-8). These solvents have intermediate polarity that provides both adequate fluidity and good compatibility with aqueous overprint varnishes, avoiding the repelling issue caused by low-polarity solvents
Data Source
AI summary
To provide a metal printing ink composition capable of achieving favorable transferability during printing without extremely increasing an oil length of an alkyd resin. The above-described problem is solved by a metal printing ink composition containing a coloring pigment, a resin, and a solvent. The metal printing ink composition comprises a rosin-modified resin having a hydroxyl value of 10 mg KOH/g or greater as at least a portion of the above-described resin, and at least one selected from the group consisting of compounds represented by general formula (1) below as the above-described solvent. In general formula (1) below, each A is independently an alkylene group having 2 to 4 carbons that may have branching, R is an alkyl group having 1 to 13 carbons that may have a branch structure and/or a ring structure, and n is an integer of 2 to 8.