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Screen printing technology of plastic bottle cap mold
Edit:Taizhou Huangyan Yige Machinery Co., Ltd.   UpDate:2018-10-25

Introduction of silk screen technology for plastic bottle caps

Pad printing is a better printing method for plastic bottle caps
When customers receive orders for bottle cap printing, the first thing that comes to mind is the pad printing process. The pad printing process is a common printing method developed following the screen printing process, similar to the rubber stamps in our daily life. Pad printing uses a relatively independent azimuth connection between the printing plate and the substrate. No matter how strange the shape of the substrate, it can accomplish its mission outstandingly. This makes the pad printing process the final choice for many missions that are difficult to accomplish with screen printing claimed to be "universal printing". The use of pad printing to print plastic bottle caps has several advantages that other printing processes cannot.

(1) Less investment. Compared with other printing equipment, less investment in printing equipment.
(2) It is convenient to change the variety and the plate making is simple.
(3) Strong adaptability. The shape of the pad can be changed at will, which makes the adaptability of the pad printing technology to the shape of the substrate greatly enhanced, which is suitable for the printing of bottle caps with different appearances and sizes. According to our investigation, about 80% of the caps will not have a diameter greater than 40mm. That is to say, a pad printer with a steel plate area of 100mm × 100mm can complete printing of about 80% of bottle caps.

Elements of plastic bottle cap printing


In plastic bottle cap printing, the choice of ink is very important. Bottle caps are basically made of PP and PE materials, and the selected ink must match the type of substrate. When selecting the ink, the following two points should be noticed.

(1) Use pad printing ink instead of screen printing ink. Screen printing inks have better leveling properties, while pad printing inks have better colloidal properties; screen printing inks have a relatively slow drying speed, and pad printing inks have a faster drying speed.
(2) A hardener is added to some inks to improve the adhesion effect, but it increases the difficulty of operation. Therefore, it is recommended not to use this method unless the customer has special requirements.
Although solvent-based screen printing inks can be used for pad printing, they are not as effective as specialized pad printing inks. If UV inks are needed, screen printing UV inks should not be used, because screen printing UV inks have poor transferability. 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 rubber heads is not paid much attention in China, but the selection of rubber heads should be very severe when printing. In the cap printing, the round rubber head is widely used. When choosing a rubber head, you need to pay attention to the following two points.

(1) In the process of printing the screen tone picture, the hardness and shape of the rubber heads used for yellow, magenta and cyan should be exactly the same, and the hardness of the rubber head used for black can be slightly larger.

(2) Select a rubber head with good release properties. This rubber head draws on the essence of some formulas of offset printing blankets, which can improve the printing quality of PP and PE surfaces.

3. Printing plate

For cap mold manufacturers who value pad printing quality, using resin gravure is a wise choice. This printing plate is made of nylon polymer, which does not require an etching process, which is good for quality management. At present, resin gravure is widely used in pad printing machines produced in Europe and America.

4. Cost

The printed area of the bottle cap is very small, so some people don't think that it needs to worry about its cost. However, as market competition intensifies, we should still pay attention to reducing costs. This is why many manufacturers currently use pad printing instead of flexographic printing when printing caps.

Currently, the price of cheap monochrome pad printers is around 10,000 yuan, including steel plates, jigs and pads. With this configuration, the monochrome printing cost of the bottle cap is generally not higher than 1 cent. If a fully automatic pad printer is used, the print volume is within 500,000, and the cost is roughly the same. With more than 500,000 copies, the cost will be reduced.

Development trend of plastic bottle cap printing

On-line production

At present in the domestic market, the most commonly used models are stand-alone pad printers. Operators must place products one by one and remove them after printing. The production efficiency is extremely low. The automatic cap printing machine integrates flame processing, pad printing and drying, and has both automatic loading and unloading functions. It is mainly used for bottle cap production in large enterprises, which can greatly improve the production efficiency. If connected to the cap production line, production efficiency will be higher. The specific process of online production of the automatic bottle cap printing machine and the bottle cap production line is: After the bottle caps transmitted from the bottle cap production line reach the pad printer, the sensor detects the presence of the bottle caps.