There are two types of plastic caps : one is a plug-in type and the other is a circular swivel type. Insert bottle caps generally do not need to be installed repeatedly, the shape is more complicated, it mainly performs some functional actions, such as spraying. Currently mainly used in plastic bottle packaging such as shower gel, hair care products and insecticides. Round rotary caps are more common and have a wider range of uses. In addition to protecting the products in the bottle from the environment, these caps also function to convey important information (such as work-manufactured products), such as the unified group's tea drinks, Porter packaging products. Plastic bottle caps.
Pad printing is the preferred method of printing plastic caps. When customers receive an order for cap printing, the first thing that comes to mind is the pad printing process. The pad printing process is a unique printing method developed with the screen printing process, similar to the rubber stamps in our daily life. Pad printing uses a relatively independent positional relationship between the plate and the substrate, and it does an excellent job regardless of the shape of the substrate. This made many tasks, which are known as "universal printing", difficult to complete, and finally chose the pad printing process.
Printing plastic caps using the pad printing process has several advantages over other printing processes:
(1) It is convenient to change the variety and the plate making is simple.
(2) Less investment. Pad printing equipment has the least investment compared to other printing equipment.
(3) Adaptability. The shape of the pad can be changed at will, which makes the padding technology more adaptable to the shape of the substrate, and is suitable for cap printing of different appearances and sizes. According to our investigation, about 80% of the caps will not be larger than 40mm in diameter. That is to say, a 100 mm x 100 mm pad printing machine can print about 80% of the caps.
Elements of plastic bottle cap printing:
1. Ink for printing plastic caps In the printing of plastic caps, the choice of ink is critical. The caps are basically made of PP and PE materials, and the selected inks must match the type of substrate. There are two main points to note when selecting inks:
(1) Some inks have a hardener added to improve the adhesion, but it increases the difficulty of operation. Therefore, unless the customer has special requirements, it is recommended not to use this method.
(2) It is best to use pad printing ink instead of screen printing ink. Screen printing inks have better leveling properties, while printing inks have better gel properties; screen printing inks have a relatively slower drying speed, and printing inks have a faster drying speed.
Although solvent-based screen printing inks can be used for pad printing, they are not as effective as special pad printing inks. If UV ink is required, screen printing UV ink should not be used because the transferability of screen printing UV ink is too poor. If screen printing UV inks must be used, a certain amount of gelling agent should be added to them.
2. Plastic head
At present, the selection of plastic heads is generally not taken seriously in China, but the selection of plastic heads should be very strict when printing. Round head applications are common in bottle cap printing. When choosing a plastic head, you need to pay attention to the following two points:
(1) In the printing process of the mesh image, the hardness and shape of the rubber heads selected for yellow, magenta and cyan are exactly the same, and the hardness of the rubber head selected by black can be slightly larger.
(2) Select the rubber head with good release property. This kind of rubber head draws on the essence of the formula of the offset blanket, which can improve the printing quality of PP and PE surface.
3. Plate
For cap manufacturers who value the quality of the print, it is wise to use a resin intaglio. This type of plate is made of nylon polymer, which does not require a corrosion process and is beneficial to quality management. At present, resin gravure is widely used in pad printing machines produced in Europe and America.
4. Cost
The area printed on the cap is small, so some people think that there is no need to worry about its cost. However, as market competition intensifies, it should be noted that costs should be reduced. This is why many manufacturers currently use pad printing instead of flexographic printing when printing caps.
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