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How to Fix ”glue does not dry” in Interlayer Strip Distribution in solventless dry lamination products:Analysis and troubleshoot

The non-drying phenomenon of “adhesive in strip distribution” is a common problem in solventless dry lamination processing.



Table of Content:

1. Adhesive consumption related to the non-drying phenomenon of “adhesive in strip distribution”

2. General cause

3. The phenomenon in the interlayer strip distribution may exist in two states

4. Troubleshooting & Fix steps tips


1. Adhesive consumption related to the non-drying phenomenon of “adhesive in strip distribution”

In this phenomenon, the width of the strips is generally between 1 ~ 5 cm, and the length ranges from 0.5 ~ 2 meters. Moreover, it appears randomly and repetitively in both the running and transverse directions of the laminated film.

The area affected by the “non-drying of adhesive” or “glue does not dry” phenomenon mentioned above is approximately 0.005 ~ 0.1 ㎡. Assuming an average adhesive amount of 1.5g/m², the adhesive consumption related to the “glue does not dry” phenomenon is 0.0075 ~ 0.15g.


2. General cause:

This phenomenon is generally not caused by a proportion imbalance or uneven mixing of the adhesive pump during synchronous operation but rather due to the (pneumatic valve close lax), resulting in a leakage of a component; or the (asynchronous operation of the adhesive-mixing pump).

When the adhesive-mixing pump stops dispensing adhesive, the pneumatic valve cuts off the pipelines of both adhesives simultaneously. As the adhesive inside the adhesive tube is under pressure during the dispensing process, if there is an inadequate closure of the pneumatic valve at the moment of cutting off the adhesive pipelines, a small amount of Component A or Component B may permeate out, creating a situation where only Component A or Component B is present at the inlet of the static mixer.

The “asynchronous operation of the adhesive-mixing pump” refers to the situation where the pneumatic valve is already open when the adhesive pump starts dispensing, but at this time, one of the two dispensing pumps starts slightly earlier (not simultaneously, with a difference of a few milliseconds or tens of milliseconds), resulting in a condition where only Component A or Component B is present at the inlet of the static mixer. The phenomena of “inadequate closure of the pneumatic valve” or “asynchronous operation of the adhesive pump” can occur in the pipelines of both Component A and Component B.


3. The “non-drying of adhesive”/”glue does not dry” phenomenon in the interlayer strip distribution may exist in two states

(1) If the affected area is cut open and exposed to the open environment for half an hour or one hour, and the degree of “glue does not dry” decreases or disappears, it indicates that the phenomenon is caused by the leakage of Component A or the premature start of Pump A.

(2) If the degree of “glue does not dry” remains unchanged, it suggests that the phenomenon is caused by the leakage of Component B or the premature start of Pump B.


4. Troubleshooting & Fix steps tips

(1) For such “non-drying of adhesive” phenomena, the pneumatic valve should be disassembled and cleaned first to confirm whether it is blocked. If the blockage of the pneumatic valve can be ruled out as the cause, adjustments should be made to the control system or adhesive ratio of the adhesive pump.

(2) Regarding the adjustment of the adhesive ratio, it is recommended to follow the ratios provided by the adhesive factory during production. If it is necessary to adjust the ratio of Component B, it is suggested to make adjustments in multiples of 5%.

(3) Regarding the adjustment of the adhesive pump's control system, it is recommended to reduce the amount of adhesive dispensed per unit time and lower the lateral movement speed of the dispensing head.

(4) If the above measures still prove ineffective, it is advisable to seek assistance from the equipment supplier to inspect the adhesive pump control system.

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