Selection Principles and Solutions for Water-Based Ink Defoaming Agents

Selection Principles and Solutions for Water-Based Ink Defoaming Agents

I. Classification of Four Major Defoamers, Their Advantages and Disadvantages, and Applicable Scenarios

1.Mineral oil defoamer (low-end carton ink)

Ingredients: White oil with fatty acid hydrophobic particles

Advantages: High cost performance, rapid bubble elimination, minimal shrinkage, and excellent compatibility

Drawbacks: Poor defoaming capability and difficulty in eliminating fine bubbles, which can lead to film loss of gloss and reduced water resistance. Additionally, safety restrictions prevent its application in food packaging

Addition amount: 0.2% to 1.2%

Applicable: Ordinary corrugated cartons, low-grade rosin acrylic ink, and uncoated paper products

2. Silicone-free polyether defoamer (Preferred for Food/Composite Ink)

Ingredients: Silicone-free ethylene oxide-propylene oxide block copolymer

Advantages: It exhibits excellent system compatibility, ensuring no impact on low-foam, alcohol resistance, and high-temperature stability while eliminating the risk of silicone migration. This approach avoids shrinkage defects while maintaining the stability of film adhesion force

Drawbacks: Slow defoaming speed and low efficiency, making it difficult to achieve effective results with a single method when dealing with massive foam

Addition amount: 0.2% to 0.8%

Applicable: PU soft packaging ink, food-grade ink, transparent varnish, and printing systems requiring dry lamination

Recommended Model: RK-3062G

3. Polyether modified silicone defoamer (mainstream in the market)

Weakly modified high compatibility silicon/efficient microbubble silicon

Advantages: It has good dual effects of bubble breaking and bubble suppression, which can completely remove macroscopic bubbles and hidden microbubbles, and maintain stable performance under high shear conditions of high-speed grinding and printing cycles

Disadvantages: Excessive addition can easily cause fish eye and shrinkage defects, while high levels of free silicone oil can cause delamination problems in composite materials due to migration.

Addition amount: 0.05% to 0.4% (strictly controlled upper limit)

Applicable: Cardboard high gloss ink, high pigment charcoal black paste, ordinary color printed cardboard box

Recommended model: RK-8403

4. Silicon polyether composite defoamer (mid to high end versatile)

By synergistically compounding organosilicon and polyether, the compatibility of the system is optimized while ensuring foam breaking, achieving a dual balance between defoaming performance and dispersion stability

Advantages: It combines fast foam breaking and long-term foam suppression performance, perfectly adapting to the dual application needs of film and paper while effectively reducing the risk of shrinkage in pure silicon

Applicable: Export cardboard boxes, labels, light laminated ink wash

Recommended models: RK-8405, RK-8409E

II、 Match according to ink resin

1. Rosin modified acrylic acid (low-cost corrugated cardboard box)

Economy: Mineral oil defoamer; Export/Highlight Requirement Scenario: Composite Modified Organosilicon Defoamer

2. Pure acrylic acid/styrene (cardboard, high gloss label)

Preferred weakly modified organosilicon or silicone polyether composite defoamer, accurately eliminates grinding microbubbles, ensuring the gloss of the protective film

3. Water based PU flexible packaging ink (BOPP/PET/PE)

To prevent interlayer adhesion failure and coating peeling, high mobility silicone oil defoamers should be discarded and replaced with silicon free polyether or low migration composite silicone products

4. Resin free high solid color paste (carbon black, phthalocyanine pigment)

For the dense microbubbles generated under high shear conditions, only a small amount of highly efficient modified organic silicon defoamer needs to be added to achieve rapid elimination

III、 Divided by printing substrate and post-processing technology (key points for avoiding pitfalls)

1. Corrugated paper, non laminated cardboard box

Low cost: mineral oil; Food export cardboard box: silicone free polyether/composite defoamer

2. Copperplate cardboard, high gloss labels

To avoid fogging and loss of light defects caused by mineral oil, modified organosilicon and composite defoamers should be selected

3. BOPP and PET plastic films require lamination/dry lamination

Red line: Pure silicone oil and high silicon content defoamers pose instability risks of silicon component migration and precipitation, as well as system stratification

Solution: Based on a silicon free polyether defoamer system, to enhance defoaming efficiency, low migration composite silicon with a dosage not exceeding 0.15% can be compounded

4. Food contact grade ink that is resistant to steaming, boiling, and water boiling

Prohibit mineral oil and high free range silicone oil type defoamers; Food grade polyether defoamer, compliant low silicon composite defoamer

5. Transparent varnish and varnish system

For systems prone to shrinkage, silicon free polyether defoamers are preferred to avoid defects caused by surface tension differences, and the use of organic silicon additives is strictly limited

IV、Selection plan for ink foaming

1.During the grinding stage, a large amount of floating and large bubbles are generated, which can be treated with mineral oil or modified organosilicon defoamers.

2. Post press pinholes, ink layer microbubbles, and high-speed printing block problems can be effectively eliminated by using polyether modified silicone additives to ensure smooth and defect free coatings.

3. For the continuous and repeated foaming problem caused by insufficient anti foaming performance during the printing process, the preferred choice is a silicone polyether composite defoamer that combines rapid foam breaking and long-term anti regeneration ability.

4. For the frequent occurrence of fisheye and shrinkage problems in light colored transparent ink, it is recommended to use silicone free polyether defoamers and reduce the amount of silicone additives used.

5. The layering and thickening problems of ink during thermal storage are mainly attributed to excessive addition of mineral oil or poor compatibility of silicone oil. It is recommended to optimize the stability of the system by replacing it with a composite defoamer.

V、Add specifications and feeding sequence

Suggested addition amount (total ink mass)

Mineral oil: 0.3~1.0% | Silicon free polyether: 0.2~0.7% | Modified organosilicon: 0.05~0.4% | Composite defoamer: 0.1~0.5%

Optimal feeding steps

1. Pre mix water, dispersant and wetting agent, and add half of defoamer to implement pre foam suppression, so as to reduce foam generation during grinding.

2. After high-speed dispersion and pre mixing of pigments, they are finely ground using a sand mill

3. Add resin lotion, alcohol solvent and film forming agent, and then slowly add residual defoamer under low-speed stirring state.

Practical skills: To prevent shrinkage caused by excessive local concentration, it is necessary to dilute the defoamer with deionized water or ethanol in a ratio of 1:5 and ensure uniform dispersion before adding it.

VI、Common selection misconceptions

1. The more defoamers, the better the effect. Excessive use can lead to paint film defects: excessive use of silicone can easily cause fish eyes and film delamination, while excessive use of mineral oils can reduce glossiness and water resistance.  

2. Ordinary organosilicon migrates in PU film ink, resulting in unsatisfactory composite peel strength and causing large-scale batch scrapping.  

3. Failure to add defoamers during the grinding stage results in permanent encapsulation of microbubbles, which cannot be completely eliminated even if they are added before printing, ultimately leading to pinholes and white spots in the finished product.

4. Mineral oil can cause haze in the transparent ink layer, seriously damaging its transparency and glossiness.

VII、Quick Selection Comparison Table