Application of corona treatment equipment on dry laminating machine
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Plastic flexible packaging is now widely used in various fields of commodity packaging. The most commonly used non-polar film such as polyethylene and polypropylene in flexible packaging is a non-polar material. The surface is dense and smooth. It is an inert surface with a surface free energy of only 2.9-3.0×10ˉ6J/cm2. Theoretically, a film having a surface free energy of less than 3.3 × 10 ˉ 6 J/cm 2 cannot infiltrate any of the currently used adhesives. Therefore, it is necessary to firstly pass the surface treatment to make the surface free energy of the film reach 3.8-4.0×10ˉ6J/cm2, which is beneficial to obtain good composite strength. There are many methods for surface treatment of commonly used films, and corona treatment is a commonly used method.
When it is necessary to process, the film may be inserted between the electrode rolls in order. The treated film directly enters the printing unit, and the adhesion of the ink on the film is good. The installation of corona treatment equipment on the dry laminating machine is one of the technical changes of our factory. The purpose is to increase the surface tension value of the polyethylene hydrocarbon film and improve the adhesion fastness of the composite product. After the corresponding point spark treatment equipment was equipped on the dry laminating machine according to the actual situation, good results were obtained. The processing equipment adopts the DCD16-2-10 plastic surface treatment machine produced by Dalian Radio 9 Factory. After corona treatment, the surface tension of the film can reach 3.8 ~ 10 ˉ 2 N / cm 2, so that the peel strength of the composite film is greatly improved, and the quality requirements can be fully achieved. Aluminized film, especially BOPP aluminized film, is very helpful, but it has to be changed in the installation and wiring of the equipment. The following sections will be discussed from the aspects of corona treatment principle, surface tension detection method, equipment installation wiring and common troubleshooting.
1 Corona treatment principle
Electro-impact or breakdown, under the action of a high-voltage electric field, the strong impact of the electron flow on the plastic film can cause the surface of the film to fluff, become rough, and increase the surface area. When the adhesive is in contact with its surface, it can produce good wetting. The adhesive will penetrate into the napped groove and firmly bond the film by "anchor". This is a physical effect and is observed under a high magnification magnifying glass. The surface of the film is relatively rugged and rough relative to the untreated film, and the electrical impact strength can be increased with increasing voltage and current.
2 increase the polarity of the film
Under the action of a high-voltage electric field, the oxygen in the air turns into ozone, which is decomposed into oxygen and new ecological oxygen atoms. The new eco-oxygen atom is a strengthening agent that oxidizes a-carbon atoms in polyethylene or polypropylene molecules to form carbonyl groups and hydroxyl groups. With this structure, the molecular weight of the film increases and the surface tension increases. The affinity of the adhesive increases and the bond fastness between the composite films increases. In addition, since the hydroxyl group is generated, a new a-carbon atom is generated in the molecular chain, and the active hydrogen can chemically react with the active group isocyanate (-NCO) in the polyester adhesive. A strong chemical bond is formed between the adhesive material and the adhesive to increase the bond fastness. From the infrared light detection, it was found that there was a carbonyl absorption peak on the surface of the treated polyolefin film, which proved that the above chemical action was present.
3 commonly used detection methods
1. Peel the test with BOPP single-sided transparent tape, paste the BOPP single-sided tape on the surface of the film to be tested, press it tightly and then tear it open. If the surface tension of the film meets the requirements of use, it is very hard to peel off and the sound is small; on the contrary, it is easily peeled off and mixed with "sand" sound.
2. The test was carried out using a Dyne pen: BOPP: 3.8 × 10 ˉ 2 N/m when the film surface tension value was satisfactory; PET: 5.0 × 10 ˉ 2 N/m; nylon: 5.2 × 10 ˉ 2 N/m. Test the pen where the liquid marks are even, without breaking or shrinking. If a part shrinks and part does not shrink, the treatment is not enough. It is worth mentioning that when testing PET and nylon, a large-scale test pen must be used. The common specifications of the surface tension test pen are: 3.8×10ˉ2N/m; 4.0×10ˉ2N/m; 4.2×10ˉ2N. /m; 4.4 × 10 ˉ 2 N / m; 4.8 × 10 ˉ 2 N / m 5 kinds (for measuring aluminum foil).
3. Self-formulation of surface tension test liquid as shown in Table 1:
The treated film should not be placed for too long, and it can be placed for up to 7 days. The longer the time, the more obvious the surface tension value decreases. If it is required to be left for a long period of time, the initial value of the surface tension is increased when the film is processed.
4 equipment common faults and troubleshooting methods
SDCD16-Z-10 corona treatment equipment sometimes has some faults during use, including electrical faults and mechanical faults. The following is a breakdown of the problems I encountered in actual work for reference.
1. The equipment does not generate sparks, the positive pole on the impact frame and the aluminum row does not discharge. This kind of failure often occurs in the rainy season. Due to the large indoor humidity, there is water on the discharge aluminum discharge on the impact frame and the insulator silicone rubber roller, causing the positive electrode to discharge and the aluminum discharge to be discharged. The treatment method is: the main power source is turned off, and all the rollers (including the traction roller and the insulating silicone rubber roller) and the discharge aluminum row of the impact frame are wiped dry with a dry cloth. And the electric blower is used for heat treatment. Without water, the discharge equipment can work normally. After encountering the above situation, the impact machine should be turned from small to large. At the same time, the spark condition is observed, and the normal spark is continuous, no red spots, and uniform.
2. The discharge aluminum row is not discharged, and the voltage does not rise (refer to the KV meter). The current (A) indicates a large value. Cause: The processing equipment is connected in parallel, the diode is damaged, or connected in series, the capacitor damage is broken down; the high voltage transformer is wired incorrectly; the thyristor damage in the processing equipment is broken; the high voltage transformer carbon brush is not in good contact or the slip ring is oily; the control panel The overcurrent switch on the circuit is damaged; the triode on the circuit board is damaged and cannot be amplified; the high voltage transformer winding is broken or the damaged porcelain bottle is broken; the positive and negative terminals of the high voltage transformer output are connected, and leakage or breakdown occurs. Countermeasure: measure the capacitance and resistance value of the diode, if it is damaged, replace it with new one; correct wiring, green line in the middle, red line on both sides; replace the thyristor tube; check the carbon brush and grind it with 1000# water-resistant sandpaper. Until it is clean; replace the overcurrent switch; replace the triode; carefully check the winding, replace the insulated porcelain bottle; replace the same model, the same specification of the line; replace the new AC contactor.
3. When the BOPP and PE films are processed, the discharge aluminum discharges electricity, and when the VMOPP and VMCPP films are processed, the discharge aluminum row is not discharged. Reason: The diode of the processing equipment was broken down; the silicone rubber insulating roller on the impact frame was broken down, and the sound of "啪" was heard when handling VMOPP, the spark was only a little bit; the positive and negative wires of the output end of the high voltage transformer touched Conductor, even leakage or breakdown; wrong wiring between positive and negative; oily or dirty on discharge aluminum row. Countermeasure: replace the diode; replace the silicone rubber insulation roller; the connection line should be suspended in the air, can not touch the conductor, if it is broken, it should be replaced; replace the positive and negative wiring; wipe the oil and so on.
During the use of SDCD16-2-10 corona treatment equipment, the discharge aluminum row can be adjusted according to the width and width of the material, but it is strictly prohibited to touch it by hand to ensure safety. After the treated film is tested, the surface tension value is sufficient, not the bigger the better, it is worth mentioning: when impacting VMOPP, VMCPP film, the high and low transformer must be reversed with the positive and negative wires on the impact frame, that is, Said, the positive pole of the impact frame is connected to the negative pole, and the negative pole is connected to the positive pole or the live wire.
The application of the point spark treatment equipment on the dry laminating machine greatly improves the composite strength quality of the product. In the actual use and installation process, it must be operated by professionals and pay attention to the safety of use.