Author: Site Editor Publish Time: 2021-05-08 Origin: Site
Thermal transfer is an emerging printing process, which has been introduced from abroad for more than 10 years. The process printing method is divided into two parts: transfer film printing and transfer processing. The transfer film printing adopts halftone printing (resolution up to 300dpi), and the pattern is printed on the surface of the film in advance. The printed pattern has rich layers, bright colors, and ever-changing , The color difference is small, the reproducibility is good, it can meet the requirements of the designer, and is suitable for mass production; the transfer process is processed by a heat transfer machine (heating and pressure) to transfer the exquisite pattern on the transfer film to the product On the surface, the ink layer and the surface of the product melt into one body after forming, which is vivid and beautiful, which greatly improves the grade of the product. The heat transfer process is applied to the surface of various ABS, PP, plastic, wood, coated metals and other products. At present, the heat transfer process has been widely used in plastics, cosmetics, toys, electrical appliances, building materials, gifts, food packaging, stationery and other industries.
1.The principle and characteristics of thermal transfer process
The principle of thermal transfer is to print the color pattern on the heat-resistant substrate film in advance (through a release process), and then cooperate with a dedicated transfer equipment to transfer to the surface of the product by a hot stamping method. The quality of the thermal transfer process Reliable, stable technology, good material formulation and close coordination with equipment. The characteristics of the thermal transfer process: simple operation, few production procedures, high efficiency, no pollution, small land occupation, and low investment. After printing, the adhesion is good, the gloss is high, the graphics and text are clear, the color is accurate, the color is bright, safe and non-toxic. After hot stamping, it can be processed by oil spraying and sandblasting, two-shot injection molding, bending and punching.
Due to the continuous advancement of technology, the products that have been maturely developed using thermal transfer technology include: clothes, cloth bags, hats, pillows, mugs, porcelain plates, ceramic tiles, watch cases, mouse pads, coasters, hanging calendars , Medals, pennants, work cards, house numbers, mirror boxes, metal hip flasks... etc. hundreds of commodities. According to different transfer materials and equipment, the thermal transfer process is different. The following is a brief description of several common thermal transfer processes.
2.1.The production process of thermal transfer banners
(1) Computer processing: first use the computer to process the characters to be printed;
(2) Engraving: Use an engraving machine to engrave the characters or pictures processed in the computer on the transfer paper;
(3) Peel off the extra parts as needed;
(4) Overlap the composite paper and the transfer cloth, and put them together in the heat transfer machine;
(5) After the heat transfer machine is heated and pressurized, the disperse dye on the composite paper penetrates into the cloth, thus forming a banner.
Note: Combine the engraved thermal transfer paper with the blank banner cloth, with the colored side facing the cloth, and heat with a pressing force through the thermal transfer banner machine, the color of the content on the thermal transfer paper will be Will move to the blank banner cloth, thereby forming a banner with content.
2.2. The transfer process flow on light-colored or white chemical fiber garments
Use thermal transfer ink printers and ordinary paper for printing.
(1) Select the picture, print the picture on a printer with thermal transfer ink on special paper, and select mirrored printing;
(2) Place the printed picture on the garment to be transferred repeatedly to determine the specific position and make a mark;
(3) Pull up the pressure handle of the heat press machine, place the T-shirt flat on the plate of the heat press machine, do not have wrinkles on the fabric, and place the picture face down on the correct position of the clothes to be transferred. Set the temperature and temperature of the heat press machine. time;
(4) Turn on the power, when the temperature of the heat press machine reaches the set value, the machine will automatically enter a constant temperature state, and press the handle to start heat transfer;
(5) By heating and pressing the flat ironing machine, when the time is up, the buzzer will sound, lift the pressure handle, take out the transferred clothes, tear off the bottom paper, you can see that the bright patterns have been transferred On clothing.
2.3.Transfer process flow on light-colored or white pure cotton clothing
Use pigment ink printers and light-colored transfer paper for printing.
The method is similar to 2 with three main differences:
(1) The paper and ink used are different from 2;
(2) One more step after printing is to cut off the extra white edges around the paper after printing on the light-colored transfer paper. If there are many blank spaces in the middle of the picture, you can also use scissors to hollow it out;
(3) The heat transfer time is different, the heat transfer paper usually takes a little shorter time.
2.4.The transfer process flow on dark clothing
Use pigment ink printers and dark transfer paper for printing.
(1) Printing: After the picture is made, put the dark transfer paper into the pigment ink printer, and the mirror printing cannot be used in the print setting;
(2) Cut: After the dark transfer paper is printed, after the image is completely dry, be sure to cut it along the blank edge of the image with scissors (the white edge cannot be seen after trimming), and some pictures can even hollow out some blank parts in the middle , So that it is not easy to form an airtight transfer part, alleviating the "one board" phenomenon;
(3) Tear: tear off the sticker on the back of the dark transfer paper picture (otherwise the picture cannot be pasted on the cloth), and then place the picture on the transfer position of the clothes with the pattern facing upwards;
(4) Cover: The picture is facing up, and a piece of paper is placed on the dark transfer paper for isolation. This paper is called isolation paper. Separating paper is generally matched when purchasing dark transfer paper (a silicone resin paper that can be used repeatedly). If there is no separating paper, you can use the sticker on the back of the dark transfer paper that has been torn off.
(5) Hot: Press the handle to heat the transfer, and finally remove the isolation paper and take out the clothes.
2.5.Transfer printing process on cups and plates
Use thermal transfer ink printer, inkjet paper or special paper for printing.
(1) The cups and plates mentioned here are all special cups and plates for heat transfer, which are coated beforehand. The appearance size of cups and plates should be consistent with the molds of the cup ironing machine and the ironing plate machine;
(2) The size of the printed picture should be the same as or smaller than the size of the transfer position on the cup or plate, and mirror printing must be selected during printing;
(3) The picture faces the cup or the plate and put it in the correct position. The cup also needs to be glued to the side with an adhesive tape. Try to make no gap between the picture and the cup. The temperature of heat transfer on porcelain should be higher and the time should be longer;
The specific operation of thermal transfer seems simple, it can be done in a few seconds at most a few minutes, but due to different pictures, different transfer films used, different transfer methods, especially the properties, thickness, color and even origin of the substrate And so on, the temperature and time of the transfer are different, and it is difficult to achieve the best effect if it is not mastered.
2.6. Use an electric iron for thermal transfer process
Due to the limitation of the calorific value of the electric iron, it is generally not possible to transfer items above A4 size (20×30cm). The electric iron must be adjustable, and the greater the power, the better;
(1) First, set the iron to cotton gear (that is, about 170-190℃), and preheat until the heat preservation indicator light is on;
(2) Put the clothes flat on the ironing board, and iron the parts to be printed with an iron for a few seconds to remove moisture;
(3) The transfer paper is placed flat on the part of the clothes to be transferred with the printing side down, and the four corners of the paper are pasted with stickers to prevent the paper from moving;
(4) Spread the high temperature resistant flexible asbestos cloth on the clothes with transfer paper, and flatten it with four clips on the edge of the ironing board;
(5) Use an iron to slowly press the heat-resistant cloth with transfer paper back and forth for 20-30 seconds. The time depends on the size of the pattern.
(6) Remove the transfer paper from the clothes while it is not cooling, otherwise it will stick.
2.7:Aluminum transfer production process flow
(1) Use a film machine to cut the thermal transfer film to the required size.
(2) Use the transfer ultrasonic packaging machine to weld the cut transfer film into a workpiece packaging bag by ultrasonic welding according to the size of the workpiece.
(3) Insert the work piece package bag made of transfer film on the packaging platform.
(4) Place the work piece wrapped with the transfer film on the platform of the thermal transfer machine trolley, and place 18 aluminum materials in turn, connect the vacuum taps to the two ends of the aluminum materials and lock them, and turn on the vacuum switch. Close to the aluminum material. The trolley automatically sends the aluminum material into the baking furnace, the baking furnace automatically heats up to 220 degrees and keeps it for 3 minutes, and the trolley automatically exits the baking furnace.
(5) Loosen the vacuum tap and remove the workpiece.
(6) Remove the transfer film and check the quality of the workpiece.