Label thermal transfer printing commentary (below)

Fourth, the label thermal transfer printing should pay attention to the problem

The thermal transfer printing of labels usually goes through two printing processes. First, the raw materials are printed by a labeler, die-cut, discharged and rewinded, and then the rolled labels are printed on a bar code printer. The principle is that the heated print heads are the same color. With contact, the ink on the ribbon is transferred to the label material by heat and contact pressure. The thermal transfer ribbon is coated on one side with a wax-based, resin-based, or mixed ink polyester or other high-density film, and a lubricant is applied on the ink-free side to prevent wear and damage to the print head.

The ribbon consists of a handle, a front lead, a carbon ribbon, and a back lead. Pull handles and front guides are in front of the carbon precursor, and rear guides are in the end of a roll (and some do not have back guides). The carbon precursor is generally composed of a top coat, an ink layer, an inner coat, a tape base, and a back coat.

Top coat: used to improve the adhesion of ink on the label and enhance the resistance of the environment;

Ink layer: used to print and determine the characteristics of the ribbon;

Inner coating: It can make the printing surface smooth and ensure the consistency of ink release from tape base;

With base: the carrier of other layers determines the performance of heat conduction; back coating: is a special coating applied on the back of the ribbon, which can reduce the wear of the print head, reduce the generation of static electricity, and strengthen the heat conduction.

The front lead is usually transparent or other colors, its main role is the printable product name, company name and trademark, etc., for marketing and promotion. The front belt can be used to easily put the ribbon on the printer, smoothly enter the working state, and protect the carbon in the storage and transportation. Rear lead is mainly used as a warning, so that the printer senses the end of the ribbon, different printers have different rear lead, mainly aluminum plating, transparency, tension in three ways.

Aluminium: silver, mainly for reflective sensors, reflected light indicates the end of the ribbon.

Transparent: Used for transmissive sensors, allowing light to pass through to indicate that the ribbon is used up.

Tension: used for mechanical sensing, the change of the printer's sensing tension indicates that the ribbon is used up.

Ribbons are generally wound on paper (or plastic) shafts. The main requirement for the shaft is that it cannot be deformed and cannot slide during printing. Label thermal transfer is the use of this special ribbon, through the working principle of a fax-like print head, the toner coating on the ribbon is heated to the paper or other types of materials, due to The coating material on the ribbon can be selected according to the needs, resulting in strong adhesion, and the choice of print media can better ensure that the printed handwriting is not affected by the outside world. And this heating process, how to heat, can be given to the computer control, and various softwares that have been developed specifically for printing labels are very convenient for users, especially the generation of bar code symbols has also become such The necessary tool for software.

Heat transfer label paper can generally be divided into two kinds of paint and no paint, their surface ink absorption and smoothness are different. Printing ribbons are divided into three types: wax-based inks, resin-based inks and waxes, and resin synthetic inks. There are also several types of bar code printers, and some labels need to be printed on the printed ink surface. Therefore, printers, labels, ribbons, etc., have a great influence on the print quality of labels. The quality of the thermal transfer printer determines the effect of the label printing. Therefore, besides considering the price when purchasing the printer, the quality, the technical support of the manufacturer, the guarantee of the after-sales service, and the technical capabilities of the seller must be taken into consideration. The label printing material is rather special, and the printing volume is large and the operating environment is complicated. Some imported thermal transfer printers are gorgeous in appearance, but because there are no official offices in the country, they are only imported and sold by some part-time informal agents. It is difficult to meet the needs of customers after service and spare parts supply. Problems with the product and buying accessories become a big problem.

In the purchase of thermal transfer printers, it is also necessary to fully consider the broad and universal applicability of its printing materials, and choose compatible printers and compatible print materials, such as labels and ribbons. In addition to determining the color base (wax base, mixed base, or resin base) of the ribbon, the width and length of the ribbon when purchasing the ribbon, the following issues must be considered to ensure print quality:

1. Features of the printer

In the thermal transfer printing mode, the ribbon and the label paper are consumed simultaneously in the length direction. In terms of width, the width of the ribbon should be equal to or greater than the width of the label paper, and less than the maximum print width of the printer. Due to the different physical dimensions of each printer, the maximum roll length that can be loaded and the maximum width that can be printed are also different. In addition, the working temperature of the print head and the sensitivity characteristic of the ribbon also have a great influence on the final printing effect.

2 label paper features

Offset paper surface is relatively rough, should be used with wax-based or mixed-based carbon ribbon; PET paper surface is relatively smooth, with the use of resin-based carbon ribbon.

3. Print the durability of the graphic

If you want to print a label with good durability, you should choose a resin-based ribbon.

4. Label resistance requirements

If the label is required to be scratch-resistant, smear-resistant, corrosion-resistant, and heat-resistant, and may be frequently rubbed, the label needs to have strong scratch resistance. At this time, the resin ribbon or the mixed base ribbon should also be selected.

5. Print speed

In the case of high-speed printing, a high-sensitivity ribbon should be selected.

6. Print media

Labels for different media need to be fitted with different types of carbon ribbons. The shapes of the media include ribbons, cards, and labels. Papers, composites, and fabrics are the main materials. For example, paper type: According to the surface gloss, it is divided into high light (such as mirror copper plate, light powder paper, etc.), semi-high light (such as coated paper, etc.) and matt (such as offset paper, etc.), special paper (such as aluminum foil paper, fluorescent paper , thermal/thermal transfer paper, etc.). Under normal circumstances, high-gloss paper media are printed with resin-reinforced wax-based or mixed-based carbon tapes, especially mirror coated paper, which has a layer of synthetic material on the surface and should be treated with synthetic materials such as PET, PVC, BOPP, PE. , PS, POLYIMIDE, etc.; semi-high gloss paper can be resin-reinforced wax base and general wax base carbon tape. Metallized PET mainly includes laser iris film, brushed film, gold (silver) color (highlight, matt) and so on. These materials are stronger and more beautiful than paper materials, and they have a wider range of applications to the environment. However, the requirements for carbon tapes are high. Mixed and resin-based carbon tapes should be used.

7. Cost accounting

In general, the cost of wax-based carbon tapes is the lowest, followed by mixed-carbon tapes, and the cost of resin-based carbon tapes.

Due to the wide variety of media materials, the middle is very different. In order to obtain a satisfactory printing effect, multiple tests should be conducted according to their respective circumstances to find a suitable ribbon, and suppliers can also help with the selection.

During the printing process of the thermal transfer label, there are not many failures. Generally, the following problems should be noted during printing: (1) When the surface of the label is unevenly inked, the density is not enough, and the ink printing is not fast, the following adjustments should be made: Adjust the printhead pressure first, then adjust the printer speed, check the printhead temperature (heat, according to the Darken level), check the ribbon replacement, check the label surface smoothness and tension, try not to print on the UV printing ink surface, and Resin-based, water-based inks generally have no transfer quality problems. (2) Since the rewinding phenomenon occurs after label printing, it is necessary to pay attention to the drying problem of printing ink. Generally, methods such as reducing the printing speed, controlling the ink supply amount, prolonging the ink drying time, and adding a suitable amount of quick-drying agent to the ink may be adopted. .

Source: Network of Indian Industry: Lin water