Bubbles appearing after pre-coated film lamination? Find the solutions here.

Preface 

Pre-coated film lamination enhances product durability and water resistance. However, the issue of air bubbles appearing after lamination can compromise the appearance, reduce adhesion, and even lead to the rejection of an entire batch of products. According to industry data, the rework rate caused by air bubbles has reached a significant level. 15%-20% , increasing costs and delaying the project schedule. In fact, by identifying the root causes and addressing them effectively, it's possible to significantly reduce the bubble rate. This article breaks down the solution to bubble issues into four key aspects: hazards, causes, solutions, and preventive measures. 

I. Bubbles in Pre-coated Film Lamination 3 Major Hazard 

(1) Impact on Product Quality and Appearance 

1. The surface is uneven, obscuring the intricate pattern. / Text influences information transmission. 
2. The bubble area does not adhere tightly, making it prone to delamination over time and ultimately losing its waterproof and scratch-resistant functions. 

(II) Increased Corporate Costs 

1. Rework consumes raw materials and requires additional labor as well as increased energy consumption for equipment. 
2. Delaying the production cycle may result in customer claims or loss of orders. 

(3) Damage to Brand Image 

1. Bubble products have led customers to question our craftsmanship and quality control capabilities. 
2. End products (such as food) / Cosmetic packaging) features bubbles, which diminish consumer trust. 

II. Formation of Bubbles 6 The primary core reason 3  Category) 

(1) Material Issues 

1. Pre-coated film quality does not meet standards: uneven adhesive layer and insufficient tackiness (due to moisture). / Aging leads to); 
2. The substrate does not meet the requirements: impurities are present on the surface. / Creases, or abnormal moisture content in the paper (> 12% Easily evaporated gas, < 6% Easily absorbs moisture and may foam during later stages. 

(II) Improper Equipment Parameters 

1. Temperature is inappropriate: Too low prevents the adhesive layer from melting, while too high can cause glue overflow or substrate deformation. 
2. Pressure and speed are mismatched: Low pressure prevents air from being fully exhausted, while high speed results in insufficient time for air to escape. 

(III) Improper Operations 

1. Insufficient pretreatment of the substrate: Dust remains on the surface. / Oil stains, or ink remaining un-dried after printing (which releases gases upon heating and evaporation). 
2. Tension Control Imbalance: Pre-Coated Film / The substrate exhibits uneven stretching, resulting in wrinkles that trap air. 

III. Addressing Bubble Issues by Scenario 

(1) Material Issues: Control from the Source 

1. Replace with Qualified Pre-coated Film: Select products from reputable manufacturers, conduct a small-batch trial application first. Films that have been exposed to moisture or show signs of aging should be discarded immediately. 
2. Optimize substrate treatment: Wipe away surface impurities and smooth out wrinkles; ensure the paper's moisture content is properly controlled. 6%-12% , excessively high 40°C–50°C Drying 1-2 Hours. 

(II) Equipment Parameters: Precise Adjustment 

1. Temperature: Adjust according to the instruction manual. BOPP Membrane 60°C–80°C ， PET Membrane 80°C–100°C ), multiple bubbles can rise 5°C to 10°C (Within the limit); 
2. Pressure BOPP Membrane 0.3MPa-0.5MPa， PET Membrane 0.5MPa-0.8MPa , more bubbles can be added each time 0.1 MPa Test run; 
3. Speed: Slow down when the temperature is low. 0.5 m/s to 1 m/s When the temperature is appropriate, keep it under control. 1m/s-1.5m/s。

(III) Operational Issues: Standardized Procedures 

1. Pre-processing: Allow ink to dry thoroughly (in a well-ventilated area) 4-6 Hours, or < 50°C Dry it thoroughly, and clean the laminator pressure roller and feed inlet daily. 
2. Tension: Thin Pre-coated Film ≤25μm ） 5N-10N , thick film (> 25 μm ） 10N-15N ; The paper tension is lower than that of the film. 2N-3N , the plastic substrate matches the film tension. 

(IV) Remedies for Bubbles Already Formed 

1. Small bubbles (＜ 5mm ): 50°C–60°C Heat gun heating, followed by silicone roller rolling to remove air bubbles (distance > 10 cm Anti-scalding); 
2. Large bubbles ≥5mm ): Use a needle to puncture and vent, then inject specialized adhesive (such as EVA Rubber), followed by compaction and then allowed to stand. 24  Hourly solidification. 

IV. Bubble Prevention: 3 Major Key Measures 

(1) Material Acceptance and Storage 

1. Acceptance Check: Inspect the uniformity of the adhesive layer on the pre-coated film, and check the flatness of the substrate. / Moisture content: Non-conforming products will be rejected. 
2. Storage: Pre-coated Film Storage 15°C - 25°C Humidity 40%-60% Environment: Store the substrate and film separately. 

(II) Equipment Maintenance and Parameter Recording 

1. Maintenance: Inspect the pressure roller for wear daily, and calibrate the temperature control weekly. / Pressure System (Error) ≤±3°C ); 
2. Record: Establish a parameter table (including membrane model, temperature, pressure, etc.), and refer to historical data when changing materials. 

(III) Personnel Training and Quality Control 

1. Training: New Employee Training 1-2 Zhou (qualified after assessment and officially on duty) shares bubble treatment cases every month. 
2. Quality Control: Every Production 50 Piece extraction 1-2 Pre-inspection, full inspection before warehousing, and non-conforming products shall be categorized for handling. 

Conclusion 

The root causes of pre-coated film bubble issues often lie in the materials, equipment, or operational processes. By accurately identifying the underlying reasons and making targeted adjustments, combined with proactive prevention through standardized procedures, we can effectively minimize bubbles, thereby enhancing both product quality and production efficiency. If you encounter any special situations during your actual production process, feel free to share them in the comments section for discussion!