Paper Container Heat Seal Varnish Glue Free Water Based Sealing Varnish

Water-Based Ultrasonic Sealing Varnish is a special functional water-based coating material developed exclusively for the glue-free ultrasonic sealing process of paper containers. It enables fast paper bonding and sealing through ultrasonic thermal activation without adhesive glue. Featuring an eco-friendly water-based formula, excellent leveling performance, fast drying speed and high heat-sealing strength, it is compatible with offset and flexo in-line coating with stable operation and no plate clogging. Widely applied in the forming and sealing processes of paper cups, paper bowls, food paper boxes and paper barrels, it fully adapts to large-scale automated production lines for food packaging.

Core Product Features

1. Superior Ultrasonic Heat-Sealing Performance

Delivers excellent ultrasonic thermal activation effect. It achieves instant and firm bonding without glue application, ensuring crack-free and chip-free sealing that perfectly matches fully automatic sealing equipment.

2. Eco-Friendly, Safe and Fully Compliant

Adopts a pure water-based solvent-free formula with low VOC and no peculiar odor. It meets environmental standards for food-contact packaging and is applicable to domestic and export food-grade orders.

3. Wide Machine Compatibility & Stable Operation

Compatible with independent offline coating machines. In-line and flexo coating requires standardized coating thickness. With moderate fluidity, it avoids plate clogging and foaming and forms a flat coating film, suitable for long-term high-speed mass production.

4. Transparent Film & Excellent Protection

The transparent varnish film does not cover printed patterns. It provides waterproof, moisture-proof and wear-resistant protection, effectively improving the surface performance and overall appearance of paper containers.

5. Strong Adhesion & No Delamination

Perfectly fits various laminated cardboard substrates for ultrasonic sealing. The coating adheres firmly without peeling or paint falling during die-cutting and creasing.

6. Fast Drying & Blocking-Resistant for Pipeline Production

Fast thermal curing allows direct stacking after coating. It does not affect subsequent die-cutting and ultrasonic forming processes, greatly improving automated production efficiency.

How to choose:

1. Prefer this dedicated ultrasonic sealing model for automated forming production of paper cups, paper bowls and food paper boxes.

2. Directly select this product to eliminate gluing procedures and simplify packaging processes.

3. Choose the standard universal model for independent offline, high-speed flexo and offset in-line production lines.

How to use:

1. Stir thoroughly before use. No dilution is required under normal working conditions; viscosity can be slightly adjusted with a small amount of clean water.

2. Adjust coating roller pressure, film thickness and drying temperature to ensure uniform coating.

3. Apply targeted partial coating on sealing areas or full-size in-line coating during printing.

4. Complete thermal sealing directly with ultrasonic forming equipment without additional glue application.

5. Clean equipment rollers and plates with clean water after operation. Seal and store in a cool, dark and frost-free place away from open flames.

Q1: How to solve weak bonding and easy cracking of ultrasonic sealing?

Increase the coating thickness of the sealing area and adjust the power of ultrasonic equipment. Ensure the varnish is fully dried without over-baking to optimize thermal bonding performance.

Q2: How to solve product blocking during normal storage after coating?

Raise drying temperature and reduce machine speed to ensure complete film curing. Control coating dosage to avoid stacking blocking caused by excessive film thickness.

Q3: Why cannot ordinary varnish be used for ultrasonic sealing?

This product is added with special thermal sealing auxiliaries with ultrasonic thermal activation properties. Ordinary varnish contains no thermal bonding components and cannot realize glue-free sealing.

Q4: Is it compatible with both offset and flexo equipment?

Universal for all processes. For flexo printing, dilute slightly with clean water to lower viscosity and improve mesh passing and leveling effects.

Q5: Is it safe for food packaging contact?

It complies with food-contact environmental standards with non-toxic and non-precipitation properties, suitable for the production of food containers such as milk tea cups and instant noodle bowls.

Q6: Can water be added for dilution?

A small amount of clean water is allowed for slight viscosity adjustment. Excessive dilution will damage thermal bonding components and directly reduce ultrasonic sealing strength.

Q7: How to solve paint peeling on sealing areas during die-cutting?

Reduce baking temperature to improve film flexibility, slightly adjust roller pressure to avoid excessive coating thickness, and optimize die-cutting parameters for improvement.