Wrinkling And Peeling Of Offset Printing Ink After Lamination: Compatibility Issues Between Offset Printing Ink And Lamination Film And Improvement Countermeasures

The lamination process bonds lamination film to the surface of printed materials via lamination equipment to form a transparent protective film, which can significantly improve the gloss, wear resistance, water resistance and stain resistance of products. It has been widely applied in all sectors of the printing industry. In packaging printing, food packages, gift boxes and cartons are laminated to prevent ink wear and paper moisture absorption. In commercial printing, posters and picture albums are laminated to enhance visual texture and extend service life. In book printing, book covers and magazine pages are laminated to boost durability. The lamination process has become a vital means to increase product added value and enhance market competitiveness.

(2)Industry Pain Points of Compatibility Issues

Despite the significant advantages of the lamination process, ink wrinkling and peeling caused by compatibility issues have become a common industry pain point. According to incomplete industry statistics, the scrap rate in the lamination process for small and medium-sized domestic printing enterprises is generally 5%-10%, and even exceeds 15% for products with high ink coverage. An excessively high scrap rate not only increases raw material and labor costs but also delays delivery schedules, potentially leading to contract breaches. Meanwhile, frequent rework and complaints damage corporate reputation, impeding the industry's progress toward high quality, high efficiency and low cost.

(1)Typical Manifestations of Ink Wrinkling

Ink wrinkling is the most common problem after lamination, characterized by irregular folds, ripples or bubble-like protrusions on the ink layer of printed materials. In severe cases, an "orange peel texture" forms, mostly concentrated in areas with thick ink accumulation such as text and pattern edges. Mild wrinkling affects visual aesthetics, while severe wrinkling causes separation between the ink layer and the lamination film, directly resulting in product scrapping.

(2)Typical Manifestations of Ink Peeling

Ink peeling is more serious than wrinkling. After lamination, the ink peels off or turns into powder with a light wipe, and substrate exposure occurs in some areas. During subsequent cutting and folding, the ink layer is prone to fracture and peeling, failing to meet the wear resistance requirements of packaging. Food packages may even pose potential safety hazards of ink contamination, while gift boxes will be significantly downgraded.

(3)Differentiated Manifestations of Compatibility Issues

Compatibility issues show obvious differences: resin-based offset printing ink has better compatibility than oxidation-drying ink. BOPP lamination film is widely used due to its low cost and high transparency but has poor compatibility with some inks; PET lamination film offers good compatibility but at a higher cost. High-speed lamination is more prone to problems due to short contact time and concentrated pressure, while low-speed lamination may cause aging and wrinkling of the ink layer due to prolonged exposure to high temperatures.

(1)Characteristics of Offset Printing Ink

•  Ink composition: Resin, as the "binder" of ink, with an excessively low content weakens adhesion. Unreasonable additive ratios lead to abnormal drying and unbalanced surface tension. Mixing different brands or types of ink easily causes component conflicts, increasing the risk of wrinkling and peeling.

• Ink dryness: Laminating when the ink is only surface-dried but not fully cured internally will damage the ink layer under high temperature and pressure. Over-drying makes the ink layer brittle and prone to cracking and peeling under pressure. High temperature and humidity prolong the drying time.

• Surface tension: A mismatch in surface tension between the ink and the adhesive layer of the lamination film prevents the adhesive layer from fully wetting the ink surface, resulting in weak bonding.

(2)Characteristics of Lamination Film

• Adhesive layer type: Solvent-based adhesive layers tend to dissolve part of the ink; water-based adhesive layers have weak viscosity; hot-melt adhesive layers impose high requirements on process parameters. Uneven adhesive layer thickness and unstable viscosity also lead to uneven stress distribution.

• Substrate characteristics: BOPP substrates have low surface tension, resulting in weak bonding if the adhesive layer is improperly treated. PET substrates offer good compatibility but at a higher cost. Dust and oil stains on the substrate surface hinder bonding between the adhesive layer and the ink layer.

(3)Lamination Process Parameters

Excessively high temperature softens the ink layer and causes wrinkling, while excessively low temperature prevents the adhesive layer from fully melting and leads to peeling. Excessive pressure squeezes the ink layer, while insufficient pressure results in weak bonding. Excessive speed leads to inadequate contact between the adhesive layer and the ink layer, while slow speed easily causes aging and brittleness of the ink layer. Different inks and lamination films have varying requirements for process parameters.

(4)Other Auxiliary Factors

The surface smoothness and ink absorption of printing paper affect ink adhesion and drying speed. Unbalanced ambient temperature and humidity lead to slow ink drying, reduced adhesive viscosity or brittleness of the ink layer, indirectly affecting compatibility.

(1)Printing Enterprises: Optimize Production Processes to Enhance Compatibility

Abandon the concept of prioritizing low cost, select ink compatible with the type of lamination film, and avoid mixing different brands or types of ink. Conduct small-batch trial printing before mass production. Reasonably adjust the drying process, ensure full ink drying with drying equipment, and optimize the drying environment. Precisely adjust lamination temperature, pressure and speed parameters based on ink and lamination film characteristics, and regularly clean equipment and check precision.

(2)Ink Manufacturers: Optimize Product Formulations to Improve Compatibility

Increase R&D investment, optimize ink component ratios to enhance the adhesion, flexibility and drying speed of the ink layer. Develop dedicated ink compatible with different lamination films and clearly mark compatibility parameters. Provide technical guidance and training for printing enterprises to assist in resolving compatibility issues, and customize dedicated ink as required.

(3)Lamination Film Suppliers: Improve Product Quality and Optimize Compatibility

Strictly control the lamination film production process to ensure uniform and stable adhesive layers. Adjust adhesive layer formulations based on ink characteristics, and strengthen substrate surface cleaning and modification. Clearly mark compatible ink types and process parameters in product specifications, provide samples for trial printing, and establish a sound after-sales service system.

(4)Industry Level: Strengthen Standard Guidance and Promote Collaborative Development

Industry associations take the lead in formulating industry standards related to compatibility, clarifying testing methods and quality requirements, and strengthening supervision and implementation. Build industry communication platforms to promote collaboration among all stakeholders, share experience, drive technological upgrading, and enhance the popularization of compatibility knowledge.

Case 1:

A small and medium-sized packaging printing enterprise suffered from ink wrinkling and peeling after lamination, with a scrap rate of 12% and frequent customer complaints. The enterprise optimized ink selection by choosing resin-based ink compatible with BOPP lamination film, extended drying time with hot air drying equipment, and adjusted lamination process parameters. As a result, the scrap rate dropped to below 3%, and customer complaints decreased significantly.

Case 2:

A large commercial printing enterprise encountered ink peeling and wrinkling on high-end picture albums after lamination. By collaborating with ink and lamination film suppliers, the enterprise customized dedicated compatible ink, improved the adhesive layer formulation of the lamination film, and adjusted lamination process parameters. The product qualification rate increased to over 99%, significantly enhancing market competitiveness.

The problem of ink wrinkling and peeling after lamination is a concentrated manifestation of insufficient compatibility between offset printing ink and lamination film, involving multiple factors such as ink composition, lamination film quality and process parameters. It affects product quality and corporate benefits and restricts industry development. Solving this problem requires joint efforts from all stakeholders: printing enterprises optimize production processes, ink manufacturers improve formulations and provide technical support, lamination film suppliers enhance product quality, and the industry strengthens standard guidance and technical exchanges. Only in this way can the compatibility issue be fundamentally resolved, promoting the high-quality development of the printing industry and achieving win-win results for all parties.