Cell phone protective film die-cutting process control

As we all know, protective film die-cutting is an essential part of the structure of electronic products, whether it is for cell phones, cameras or tablet computers, a protective film is attached to protect the product screen before leaving the factory.
The transparency, flatness and cleanliness of the protective film affect the consumer's impression of the electronic product, and a good quality protective film will also enhance the external image of the electronic product, therefore, the die-cutting factory has strict process control on the production of protective film.
Protective film material selection
When producing protective films, there are several points to note in the selection of materials. First of all, we should choose materials that are more suitable for printing and die-cutting on the basis of meeting customers' requirements, such as good scratch resistance, good ink adhesion, not easy to nourish ink, etc.
Protective film production environment control
There are two key points in the quality control of protective film products, which are to avoid scratching and soiling. To meet these two requirements, we need a good production environment first, and the die-cutting factory is equipped with an independent clean room for protective film production. Clean room is also called clean plant, clean room (Clean Room), clean room, refers to a certain space range of air in the micro-particles, harmful air, bacteria and other pollutants excluded, and the indoor temperature, cleanliness, pressure, airflow speed and airflow distribution, noise vibration and lighting, static control in a certain demand range, and give a specially designed room. No matter how the external air conditions change, the clean room is required to maintain the original cleanliness, temperature and humidity, pressure and other parameters. According to the production of products, the cleanliness of clean room has different levels: 100, 1000, 10,000, 100,000, 300,000.
In the clean room, the biggest source of bacteria and dust is the operator under dynamic condition. Therefore, before the operator enters the clean room, he must wear clean clothes and blow in the air shower room with clean air for 15 seconds to remove the dust particles attached to the surface of the clothes.
Protective film printing process control
Most plastic films (such as polyolefin films) are non-polar polymers with low surface tension, generally at 29-30mN/m. Theoretically, if the surface tension of an object is lower than 33mN/m, currently known inks and adhesives cannot be firmly attached on it, so the surface should be corona treated. Protective film material is mostly polyolefin, which needs corona treatment before printing, usually corona power is 4.0W, speed 30m/min. after corona, it needs to be printed on machine within 5 minutes, more than 10 minutes, it needs to be re-corona before printing.
During the printing process, as the protective film material will be in contact with the impression roller, the friction will cause the surface of the material to be scratched. Therefore, it is necessary to wrap all the embossing rollers in contact with the protective film with a layer of soft jelly. As we all know, protective film is an essential part of the composition of electronic products, whether it is a cell phone, camera or tablet PC, a layer of protective film should be attached to protect the product screen before leaving the factory. The transparency, flatness and cleanliness of protective film affect the consumer's impression of electronic products, and a good quality protective film also enhances the external image of electronic products, therefore, die-cutting factories have strict process control on the production of protective film products.
Protective film die-cutting process
After the printing of the protective film is completed, it should be die-cut on a circular knife die-cutting machine. During the die-cutting process, attention should be paid to avoid scratching and ink chipping, which is a phenomenon where the ink layer at the edge of the product is supposed to be full and smooth, but there is no ink at the local level.
The main reason for ink chipping in the die-cutting process is that the ink and the protective film are not firmly enough attached to the edge of the die-cutting product will make the ink layer and the protective film separated, resulting in jagged edges. Therefore, after printing the protective film, should check the ink adhesion fastness, to ensure good ink adhesion before die-cutting. In addition, when the ink layer thickness is too thick, it will also produce the phenomenon of ink chipping.
Die-cutting process is easy to cause scratches for a variety of reasons, the most common for the uneven rotation of the pressure roller, so that the material and the pressure roller to produce relative sliding caused by scratching. So in the die-cutting before the pressure roller rotation to check, to ensure that the material contact with the pressure roller rotation are flexible. In addition, foreign objects on the nip roll can also scratch the protective film and cause chrome marks, so before die-cutting, wipe the nip roll with a clean cloth dipped in alcohol to ensure that the surface of the nip roll is clean and free of foreign objects.
The shape of the protective film is generally designed according to the customer's drawings, mainly based on the screen size of the customer's cell phone product, usually a rectangle with rounded corners and a handle at the bottom right corner of the rectangle. The handle is printed on the back side and then covered with a layer of PET film to facilitate the customer's assembly and also to facilitate the consumer to remove the protective film from the screen. All shapes of protective films are die-cut with round knives, but the number of round knives needed for complex processes will increase, for example, two round knives are needed for films that require a handle, one for the handle and the other for the exterior.
Protective film packaging process control
After die-cutting, the protective film is usually rolled and cut into single pieces when packing, and every 500 pieces are packed as a group. When packaging, the protective film is wrapped with winding film and then put into plastic sealing bags. The main concern when wrapping is cleanliness, so the operator is required to wear finger gloves into the manual operation. For example, there is a protective film product that needs to be manually attached to the handle at a later stage. The operator is required to attach the handle to the exact location of the adhesive side (i.e. inside) of the protective film and to ensure that the product cannot be dirty or have foreign objects. All the above processes are required to be done in a dust-free clean room.
Cell phone protective film may look simple and the production process is not too complicated, but each step of the process is more stringent. In general, it is important to pay attention to cleanliness at all times and to avoid bending and scratching of the protective film. It is the above-mentioned details that determine the grade of the product.