Water-based ink is an environmentally friendly ink that uses water as the primary solvent, widely used in food packaging, paper printing, textile printing, and other fields. Below is a detailed explanation of the typical formulation and production process for water-based inks:

1. Basic Composition of Water-Based Ink Formulation

1. Resin (Binder)

a. Function: Provides adhesion, film-forming properties, and gloss to the ink.

b. Common Types:Acrylic Resin: Good weather resistance, fast drying, lower cost.

i. Polyurethane Dispersion (PUD): Excellent flexibility and abrasion resistance, suitable for demanding substrates (e.g., plastic films).

ii. Styrene-Acrylic Copolymer: Balances drying speed and film-forming performance.

2. Pigments

a. Organic Pigments: Bright colors (e.g., Phthalocyanine Blue, Permanent Red), must meet environmental standards (heavy metal-free).

b. Inorganic Pigments: High lightfastness (e.g., Titanium Dioxide, Carbon Black).

c. Dosage: 10%–30% (adjusted based on color depth).

3. Additives

a. Wetting & Dispersing Agent (0.5%–2%): Aids uniform pigment dispersion (e.g., BYK-190).

b. Defoamer (0.1%–0.5%): Eliminates foam during production and use (e.g., Tego Foamex 810).

c. Leveling Agent (0.1%–0.3%): Improves print leveling (e.g., BYK-345).

d. Thickener (0.2%–1%): Adjusts viscosity (e.g., Hydroxyethyl Cellulose, Polyurethane types).

e. pH Adjuster (e.g., Ammonia Water, AMP-95): Adjusts pH to 8–9 to maintain stability.

f. Preservative (0.1%–0.3%): Prevents mildew (e.g., Isothiazolinone types).

4. Water

a. Deionized Water: Proportion 40%–60%, ensures low conductivity and avoids performance issues from impurities.

2. Typical Formulation Example (For Paper Printing)

3. Production Process Flow

1. Pre-dispersion

a. Mix water, resin, wetting & dispersing agent, and part of the water with low-speed stirring (300–500 rpm).

b. Gradually add pigments and disperse at high speed (1500–2000 rpm) until初步均匀 (approx. 30 minutes).

2. Grinding

a. Grind the slurry using a sand mill or three-roll mill until fineness ≤10 μm (test method: Hegman Gauge).

b. Typically grind 2–3 times to ensure thorough pigment dispersion.

3. Let-down/Adjustment

a. Add remaining resin, defoamer, leveling agent, and other additives with low-speed stirring (500–800 rpm).

b. Adjust pH to 8.5–9.0 (using ammonia water or organic amines).

c. Pre-dissolve thickener before adding, adjust viscosity to 30–50 seconds (Ford Cup #4, 25°C).

4. Filtration & Packaging

a. Filter through 200–400 mesh sieve to remove impurities.

b. Fill into sealed containers to prevent water evaporation.

4. Key Considerations

1. Environmental Protection & Safety:

a. Select APEO-free, formaldehyde-free raw materials compliant with regulations like EU REACH, US FDA, etc.

b. Production area requires ventilation to avoid ammonia volatilization.

2. Storage Stability:

a. Storage temperature 5–30°C, avoid stratification caused by freezing or high temperatures.

b. Add 0.1% bactericide (e.g., Proxel GXL) to extend shelf life (typically 6–12 months).

3. Printability Adjustment:

a. Drying Speed: Can be increased by adding 5%–10% ethanol or propylene glycol.

b. Adhesion: For non-absorbent substrates (e.g., PE/PP), need to add 2%–5% adhesion promoters (e.g., silane coupling agents).

5. Common Problems & Solutions

(This section was empty in the original text)

6. Application Extensions

● Food Packaging Inks: Require using FDA-approved pigments and resins (e.g., alternatives to Aniline Black).

● Textile Printing: Add crosslinkers (e.g., aziridine) to improve wash fastness.

● UV-Waterborne Hybrid Inks: Combine UV curing technology to enhance abrasion resistance and gloss.

By optimizing the formulation and process, water-based inks can achieve a balance between environmental friendliness, print quality, and cost, meeting increasingly stringent green printing requirements.