Editor's Note: The label is now a wonderful gift in the packaging decoration, more and more popular with consumers; and there are many types of label printing. From the outside, the plastic bottle surface screen printing and in-mold labeling methods all belong to the “no-tag†solution. The label corners are not visible on the bottle surface and cater to the packaging grades sought by consumers. From a technical point of view, although the processes are quite different, they do not require machine labeling or manual labeling processes. From the perspective of packaging style, bright color blocks and texts with strong readability make curved screen printing a representative of simple packaging styles; while in-mold labels, delicate screens, rich layers, and colorful colors. From an investment point of view, the investment threshold for curved screen printing is low, and the in-mold label belongs to the rich game. In short, two distinctive solutions have formed a unique landscape in the plastic bottle packaging printing market.
Plastic bottle surface screen printing features
1. Printed graphics are durable
As long as it is properly printed on plastic bottles, images can be retained for a long time, which is longer than the label's durability. There will be no damage to the text due to changes in the environment's temperature and humidity.
2. Strong visual impact
There are many types of screen printing inks, and bright, matt, fluorescent, and UV inks are printed on plastic bottles to obtain rich results. Using UV ink for printing, the printed mark after curing is clear, there is a certain degree of gloss, texture is strong, and the text description is clear at a glance. The screen printing ink layer is thick and thick, and the printed graphic is conspicuous.
3. Leading simple and fashionable
In the plastic bottle surface screen printing, if the bottle is cylindrical, four-color registration has a certain degree of difficulty. If the original is a combination of several monochromatic patterns, the print registration is not as harsh, and the use of curved screen printing is more appropriate. Surface printing is suitable for printing manuscripts with a small number of lines, lines and details.
4. Flexible production
After the plastic container processing factory configures the curved screen printing production line, it can realize the production of bottle forming and printing lines. According to the customer's order requirements, the work can be arranged properly, and the customer's delivery can be delayed without being restricted by the purchase of printed labels. In addition, the replacement of the product is very convenient. For plastic bottles with a small number of prints, the plate can be quickly replaced and the delivery time can be shortened.
Due to the above characteristics of curved screen printing, it has always occupied an important position in the packaging of plastic bottles. With the prevalence of PE bottles, the descriptions and logos of the products directly printed on transparent bottles have become a fashion. In the eyes of end users such as cosmetics, daily chemical products, pharmaceuticals, food, and industrial products, curved screen printing is considered to be a distinctive packaging printing solution.
Editor's Note: The label is now a wonderful gift in the packaging decoration, more and more popular with consumers; and there are many types of label printing. From the outside, the plastic bottle surface screen printing and in-mold labeling methods all belong to the “no-tag†solution. The label corners are not visible on the bottle surface and cater to the packaging grades sought by consumers. From a technical point of view, although the processes are quite different, they do not require machine labeling or manual labeling processes. From the perspective of packaging style, bright color blocks and texts with strong readability make curved screen printing a representative of simple packaging styles; while in-mold labels, delicate screens, rich layers, and colorful colors. From an investment point of view, the investment threshold for curved screen printing is low, and the in-mold label belongs to the rich game. In short, two distinctive solutions have formed a unique landscape in the plastic bottle packaging printing market.
Surface Printing Technology Essentials
1. Color separation
The first step in color separation is to ensure that the design elements on the original meet the manufacturer's printing conditions. The thinnest line that can be printed is 0.2mm (120 lines/inch screen). If the width of the thinnest line on the original is lower than this limit, it cannot be reproduced by printing. It is recommended that users adjust the original and change the thinnest line to the thickest line. some. The original image size is slightly smaller than the printable surface area of ​​the plastic bottle. In addition, since black is not noticeable on various bottle surfaces, when the text on the user-provided manuscript is black, it should be recommended to change it to white. The second step is to use a reasonable separation method. Due to the special method of screen printing, the transferred ink layer is thick, and offset printing separation is not suitable for curved color screen printing.
The surface tone copy of surface printing is generally 15% to 85%. Secondly, the use of elliptical dots is more desirable for screen surface adjustment and screen printing. If a square gauss dot is used, four corner borders will appear at the midtone dot in the four-color printing, resulting in a serious increase in dots, and the elliptical dots will have only two corners at the same gradation. Again, the optical density of the exposed part of the color separation sheet must be at least 4.00. For high quality plastic bottle screen printing, the resolution of the imagesetter should reach 2400 dpi. In order to facilitate print registration, registration marks should be placed on the color separation film.
2. Plate making
(1) The choice of screen. Plastic screen printing screen uses a yellow screen to reduce the negative effect of light scattering on the edge definition of the image when exposed. Nylon yellow wire mesh 120-30Y is suitable for light-blocking large color block patterns and gold and silver printing; nylon yellow wire mesh 140-30Y is suitable for large color block text printing; nylon yellow wire mesh 165-30Y is the most widely used, printing text effect Especially good.
(2) Strictly control stretching force. Since plastic bottles are printed as line contacts, the screen tension is slightly lower than flat screen printing. It is recommended to use a tension measuring instrument for normalization and data manipulation.
(3) The photosensitive adhesive coating should be thin and smooth. The coating is too thick, the surface is smooth, the thickness of the transferred ink layer is thick, and the dots are enlarged so that the color is dirty; the coating is too thin and the flatness may be affected. If there is no instrument to measure and control the thickness of the photoresist coating, a 33 coating method is generally used, that is, three times of scraping, followed by drying followed by coating, for a total of three times.
Source: Coinprint