Can I Use Screen Printing Ink On Paper?
Mar 26, 2025
1. Compatibility of screen printing ink and paper
2. Pretreatment methods to improve adhesion
3. Printing parameter optimization techniques
4. Printing quality testing methods
1. Compatibility of screen printing ink and paper
Yes, screen printing ink can be used on paper, but success depends on ink type and paper characteristics:
Ink type selection:
Water-based ink: suitable for absorbent paper (such as newsprint, recycled paper), environmentally friendly but slow drying.
Solvent-based ink: suitable for uncoated paper (such as kraft paper), strong adhesion but contains VOC.
UV-curable ink: fast drying, suitable for high-speed printing and outdoor paper (such as advertising posters).
Paper characteristics adaptation:
Smooth paper (such as coated paper) requires low-viscosity ink to avoid dot enlargement.
Rough paper (such as corrugated paper) requires high-viscosity ink to ensure hiding power.
2.Pretreatment methods to improve adhesion
Corona Treatment
Mechanism:
High - voltage corona discharge oxidizes the surface, creating polar groups (e.g., -OH, -COOH) and increasing surface tension from 28–32 mN/m to 40–50 mN/m (critical for ink wetting).
Key Parameters:
Equipment: Corona treater with 1–3 kW power, 3–5 mm electrode gap
Processing Speed: 5–20 m/min (adjust based on material thickness)
Testing: Verify with surface tension pens (e.g., 40 mN/m solution beads up if treatment is insufficient).
Applications:
Metalized Foil: Used in cigarette packaging to boost UV ink adhesion from 2B to 4B (ASTM D3359).
Plastic Films: Improves adhesion on PET for labels, achieving >5 N/cm peel strength.
Primer Coating
Function:
Acts as a molecular bridge between substrates and inks via chemical bonding (e.g., silane coupling agents) or mechanical interlocking.
Primer Types & Formulations:
| Primer Type | Substrate | Typical Ingredients | Drying Method |
|---|---|---|---|
| Water - Based | Paper, cardboard | Acrylic emulsion + crosslinker | Infrared drying (80℃, 2 min) |
| Solvent - Based | Plastics, metals | Polyurethane resin + isocyanate | Ambient drying (24 hours) |
| UV - Curable | Films, (Thermal paper) | Oligomers + photoinitiators | LED - UV curing (395 nm) |
Coating Process:
Use 80–120 mesh screens for 2–5 g/m² coat weight.
Example: PE film labels coated with water - based primers show 4.5 N/cm peel strength vs. 1.2 N/cm without primer.
Humidity & Temperature Control
Objective:
Stabilize paper fibers and ink rheology to prevent post - printing shrinkage or adhesion failure.
Optimal Conditions:
Pre - Printing Heating:
For hygroscopic papers (e.g., recycled paper), preheat at 40–60℃ for 1–2 hours to reduce moisture to 6–8%.
Environmental Control:
Maintain 22–25℃ and 50–60% RH in the printing workshop.
Industry Case:
Book Covers: In winter, preheating coated paper and adjusting humidity to 55% RH prevents ink cracking caused by thermal expansion.
Advanced Pre - treatment Methods
Plasma Treatment
Advantage: Chemical - free, suitable for medical packaging (e.g., pharmaceutical leaflets).
Parameters: Argon plasma for 30 seconds, achieving 45 mN/m surface tension.
Sandblasting
Application: Uncoated kraft paper or corrugated boxes.
Process: Use 120 - grit sandpaper to create micro - roughness for mechanical interlocking.
Surfactant Cleaning
Formula: 75% ethanol + 25% deionized water.
Purpose: Remove oils and dust from glassine paper before printing.
Pre - treatment Selection Guide
| Substrate | Recommended Methods | Adhesion Targets |
|---|---|---|
| Metalized Paper | Corona + UV Primer | 4B cross - cut test |
| PE Films | Corona + Solvent - Based Primer | Peel strength ≥5 N/cm |
| Recycled Paper | Humidity Control + Water - Based Primer | 100 rubs without fading |
| Thermal Paper | Plasma + UV Primer | Curing temp <80℃ (no coating damage) |
Troubleshooting
| Issue | Root Cause | Solution |
|---|---|---|
| Ink Cratering | Low surface tension | Corona treatment + surfactant wipe |
| Inconsistent Adhesion | Uneven primer application | Upgrade to automated coaters |
| Registration Errors | Paper moisture fluctuations | 24 - hour pre - conditioning in climate - controlled storage |
3. Printing parameter optimization techniques
Mesh Selection for Pattern Complexity
The mesh count (measured in threads per inch) directly impacts ink deposition and detail reproduction:
High Mesh (200–300 TPI):
Ideal for fine details, halftones, and text. Smaller openings (15–25 µm) ensure precise ink transfer.
Example: Printing 10 - point fonts on glossy magazines requires 250 - mesh screens.
Low Mesh (80–120 TPI):
Used for solid colors and thick ink layers (e.g., 30–50 µm deposits).
Recommendation: For corrugated boxes, pair 100 - mesh screens with high - viscosity UV inks to achieve 100% opacity.
Specialized Meshes:
Duo Mesh (e.g., 150/230 TPI) balances detail and ink volume for packaging labels.
Squeegee Pressure & Angle Dynamics
The squeegee's hardness (Shore A scale) and angle determine ink penetration and edge sharpness:
Hard Squeegees (70–80A):
Best for high - viscosity inks (e.g., UV enamels) on rigid substrates like metalized paper.
Maintain 60°–75° angles to minimize mesh embedment and achieve clean edges.
Soft Squeegees (50–60A):
Suitable for low - viscosity inks (e.g., water - based) on porous papers.
Use 45°–55° angles to enhance ink transfer into deep paper fibers.
Pressure Guidelines:
Aim for 1.5–3 kg/cm pressure; excessive force causes ink flooding, while insufficient pressure leads to incomplete coverage.
Curing Optimization for Ink Chemistry
Proper curing ensures ink permanence and prevents post - printing issues:
UV Curing:
Mercury Lamps (365 nm): Deliver 800–1500 mJ/cm² for full crosslinking of UV inks.
LED Lamps (395 nm): Lower energy (300–500 mJ/cm²) ideal for heat - sensitive papers like thermal labels.
Conveyor Speed: Adjust to match ink curing time (e.g., 5–10 m/min for 365 nm lamps).
Water - Based Inks:
Natural Drying: Requires 24–48 hours at 25℃/50% RH; use airflow systems to speed up evaporation.
IR Drying: Apply 100–120℃ heat for 1–2 minutes to force - dry high - gloss coatings.
Advanced Parameter Tuning for Consistency
Ink Viscosity Control:
Add thinners (e.g., glycol ethers) for high - mesh printing to reduce viscosity to 1000–2000 cps.
Use thickeners (e.g., xanthan gum) for low - mesh printing to increase viscosity to 5000–8000 cps.
Registration Accuracy:
Use laser alignment systems for multi - color prints; ensure mesh tension uniformity (20–25 N/cm).
Environment Management:
Control humidity to 40–60% RH to prevent water - based ink drying on screens (misting systems may help).
4. Printing quality testing methods
100-grid Test (ASTM D3359)
The 100-grid test, which follows the ASTM D3359 standard, is a pivotal method for assessing the adhesion of screen printing ink on paper. This test involves using a sharp blade to carefully cut a 10×10 grid pattern with a 1mm spacing on the printed area. The cuts are made deep enough to penetrate the ink layer and reach the surface of the paper. Subsequently, a piece of 3M adhesive tape (or an equivalent with suitable adhesion strength) is firmly applied over the grid. After ensuring good contact between the tape and the ink surface, the tape is quickly peeled off at a near 180-degree angle. For non-absorbent papers such as coated papers or metallic foils, achieving a rating of ≥4B is crucial. A 4B rating indicates that only a very small amount (less than 5%) of the ink within the grid has been removed during the tape peeling process, signifying a relatively strong adhesion. This level of adhesion is necessary to withstand the normal handling and usage of the printed product without the ink peeling off easily.
Friction Test
The friction test serves as an important indicator of the ink's durability under normal wear and tear conditions. In this test, a piece of clean cotton cloth is used to wipe the printed area. The wiping is carried out with a consistent force and a defined number of times, typically 100 times. The purpose is to simulate the rubbing actions that the printed item might encounter in practical scenarios, such as being handled by consumers or being in contact with other surfaces during transportation. If, after the 100 wipes, there is no visible fading of the ink, it can be considered that the ink has good resistance to friction. This is especially important for products like labels on bottles or packaging that are likely to be touched frequently. Fading of the ink not only affects the aesthetic appearance of the product but can also lead to important information becoming unreadable.
Water Resistance Test
The water resistance test is designed to evaluate how well the printed ink can withstand exposure to water, which is a common environmental factor for many paper products. For label papers, the test requires soaking the printed sample in cold water for 24 hours. This simulates situations where the label might come into contact with water, such as in a refrigerated environment or during accidental spills. In the case of food packaging, the test is more rigorous, involving soaking in boiling water for 30 minutes. This is because food packaging often needs to endure higher temperatures and more prolonged contact with moisture, for example, during the sterilization process or when the packaged food contains a certain amount of water. If the ink remains firmly attached to the paper and there is no significant discoloration, bleeding, or peeling after the respective soaking periods, it indicates that the ink has satisfactory water resistance, ensuring the integrity and legibility of the printed information on the paper product even in wet conditions.
Screen printing inks can be successfully used on paper, but it is necessary to match the ink type, pre-treat the paper and optimize the process. Different application scenarios have different requirements for the performance of inks, such as food packaging focuses on safety and low migration, art paper products pursue color saturation and delicate effects, and express labels emphasize scratch resistance and durability. Therefore, in practical applications, the appropriate ink type must be selected according to specific needs.
Pre-treating paper is also an important part of improving printing quality. For different types of paper, non-absorbent paper may require corona treatment or primer coating to enhance the adhesion of ink; hygroscopic paper requires temperature and humidity control to reduce the impact of deformation on printing quality. By optimizing the printing process, including screen selection, adjustment of scraper pressure and angle, and control of curing conditions, the transfer effect of ink and printing quality can be further improved.
Regular testing of adhesion and durability is a key measure to ensure the stability of printed product quality. Through methods such as hundred grid test, friction test, and water resistance test, it can be timely discovered whether the adhesion between ink and paper meets the requirements, as well as the durability of ink under different environmental conditions. By collaborating with suppliers to adjust the formula, we can improve and optimize the ink based on problems and new demands that arise in actual production, thereby ensuring that printed products have stable quality in different application scenarios and meet market and customer needs.
