Abstract: This article mainly introduces the reasons for the large friction coefficient of the composite film and the process control points after PE composite curing
PE (polyethylene) material is widely used in composite flexible packaging, In the application of solvent-free composite technology, there will be some problems different from other composite methods, specially pay more attention to the process control.
- 1. Common process problems of PE solvent-free composite
1) Making bags, the bags surface very slippery and hard to collect.
2) Coding difficulty (FIG. 1)
3) roll materials speed cannot be too fast.
4) poor opening (FIG. 2)
FIG. 1
FIG. 2
- 2. The main reasons
The above problems are manifested in different forms, and the reasons are different. The most concentrated reason is that the polyether composition in solvent-free lamination adhesive will react with the slipping agent in the film, which makes the slipping agent composition that has been precipitated into the heat-sealing surface of the polyethylene film migrate inward or outward, resulting in large friction coefficient of the composite film after curing. This happens more often when the PE is thinner.
In most cases, PE process problems are not the result of a single factor, but are often closely related to several factors, including curing temperature, Coating Weight, winding tension, PE composition and solvent-free adhesive properties.
- 3. The Control points and methods
The above PE composite process problems are mainly caused by large friction coefficient, which can be adjusted and controlled by the following methods.
|
NO |
Controlling factors |
Controlling points |
|
1 |
Temperature of compounding and curing |
Compound and curing temperature should be appropriate, generally set at 35-38℃.The compounding and curing temperature are very sensitive to the increase of friction coefficient, The higher the temperature, the more severe the solvent-free lamination adhesive reacts with the slipping agent in the film. Proper temperature can ensure that the friction coefficient is suitable and does not affect the peel strength. |
|
2 |
Winding tightness |
The winding tension shall be as small as possible under the condition that there are no Core wrinkles and bubbles on the surface after the composite materials curing. |
|
3 |
Coating Weight |
Under the premise of ensuring the peel strength, the Coating Weight is controlled slightly higher than the lower limit value. |
|
4 |
Raw material polyethylene film |
Add more slippery agent or add proper amount of inorganic opening agent, such as silica differential |
|
5 |
Suitable adhesive |
Select solvent-free adhesive models specifically for friction coefficient |
In addition, the actual production will encounter a small friction coefficient situation occasionally, take some operations contrary to the above measures according to the specific situation.
Post time: Sep-30-2021