Heat transfer printing technology has long been used in the production of fabric heat transfer printing. With the rapid development of high technology, heat transfer printing technology is more and more widely used. From the types of inks, there are thermal transfer types and thermal sublimation transfer types, of which the sublimation transfer type is represented by the Sublimation transfer ink of Beijing Huijie Transfer Materials Co., LTD. From the transferred objects are classified as fabric, plastic (board, sheet, film), ceramic, and metal coating board; It can be classified into screen printing, flat printing, gravure printing, letterpress printing, ink-jet printing, and ribbon printing. From the substrate classification of heat transfer paper and heat transfer plastic film.
Thermal transfer technology is to use screen printing, gravure printing, and other printing methods, the image and text printed on water based heat transfer paper or plastic film, and then through heating pressure, the image and text transferred to the fabric, leather, and other articles.
(a) ink formula example
Screen printing thermal transfer ink formula is as follows (for reference only). The n-methoxy methyl polyamide was dissolved in solvents such as benzyl alcohol, toluene, and ethanol, mixed with heat-resistant pigment and swelling, and then ground into screen printing ink. The ink is printed onto the carrier (e.g. heat transfer paper) by screen printing, and then the fabric is hot-pressed.
(2) The structure of hot-pressing transfer paper
There are three types of paper structure. 1. It is composed of heat transfer paper, a link layer, and the adhesive layer, as shown in Figure 1. 2. By heat transfer paper, transparent off layer, ink layer, and adhesive layer. A transparent detachment layer can be used as a protective film for ink. 3. By heat transfer paper, transparent off a layer, ink layer, adhesive layer, and hot melt glue powder layer. The heat transfer paper with a layer of hot melt powder transferred out of the finished product friction resistance, fastness and adhesion are the strongest.
(3) Heat transfer printing process
Heat transfer technology can be referred to as hot stamping, hot stamping can be divided into the following categories. 1. High-temperature hot stamping: mainly used for cotton and mixed knitting clothing. Such as T-shirts, pajamas, etc. The design has a photo effect, soft after hot spring pieces. 2. Low temperature bronzing: mainly used for nylon cloth and PU artificial leather, such as stretch sportswear, swimsuit, down jackets, sports shoes, leather gloves, etc., the pattern effect after ironing is the same as high temperature bronzing. Used for elastic clothing, the elastic effect is excellent. 3. Flocking hot stamping: a wide range of applications, usually can be used for women's stockings, men's cotton foam, clothing trademarks, knitting children's wear, patterns have a three-dimensional effect, and can be multi-color collocation, hot soft, elastic, strong adhesion. 4. Permeating foaming hot stamping: mainly used for cotton, chemical fiber knitwear, woolen sweater, jeans, and so on. The main characteristic is to penetrate into the fabric, good air permeability, foaming part three-dimensional strong, raised texture good, hot feel soft, strong adhesion. Hot stamping methods and precautions are as follows. (1) Put the transfer paper pattern facing the quasi-fabric in the desired position. (2) With an iron or transfer press, apply pressure and heat for a few seconds. (3) Tear off the bottom paper (three methods). · Cooling: Slowly tear off the bottom paper after cooling completely. · Hot strip: While hot, tear off the bottom paper immediately. · Tempering: Let stand for a few seconds and, when heated, tear off the bottom sheet. (4) to iron stockings in the substrate under the silicone oil paper, to prevent hot melt adhesive seepage.
The traditional thermal sublimation transfer printing means that the sublimation transfer printing ink is printed on paper (or polyester transfer film) through screen printing, and the printed paper (or film) and the fabric are overlapping together to be heated, pressurized, or decompressed, and the dyes on the paper (or film) are sublimated to the fabric in the form of gas-phase state. In addition to the fabric, can also be transferred to ceramics, metal products. The main characteristic of sublimation transfer technology is that the transfer image has bright colors, rich layers, and the effect is comparable to that of printing. The difference with printing is that the dye in the transfer ink is sublimated by heat and permeates into the surface of the object. So heat transfer products are durable, images will not fall off, crack or fade. Along with the development of high technology by leaps and bounds, thermal transfer technology and level are also further expanded and improved, thermal transfer technology is widely used in computer image processing and design, and then through a high-speed high-quality inkjet printer to print images on paper (or film), eliminating the plate making process, and can also use the sublimation ink coating on the plastic film cutting and assaying the application on a smart card printing technology.
The method of printing on fabric by sublimation transfer paper is also called gas-phase transfer printing. The basic production method of transfer printing is to make the applicable dyestuffs into ink, and then print the colored paper, and then superposition the colored heat realease paper and the fabric together to heat, pressurize or reduce pressure. Then the dyestuffs on the paper will sublimate into the vapor phase state and transfer to the fabric.
1. Sublimation transfer ink
Heat sublimation transfer ink by the heat rise
(1) Dye-dye heat sublimation transfer printing dyes can be selected according to the following conditions: The molecular weight of the dye should not exceed 350 in general; (2) There is molecular interaction between dye gas and fiber, and can diffuse to the fiber interior; The dye heat sublimation temperature below 200℃ is more appropriate; (4) The color fastness of the dye transferred to the fiber meets the dress requirements; The color and luster on the fiber are good; Dyes and base paper no affinity. Common transfer printing dyes are anthraquinone dyes, azo dyes, cationic dyes, and so on.
(2) The commonly used resins of the binder are low viscosity ethyl cellulose, ethyl hydroxyethyl cellulose (EHEC), long oil modified alkyd resin, etc. The commonly used solvents are turpentine, turpentine alcohol, high boiling point alkanol, Arkansas, fibrinolytic agent, etc., and there are a few other additives. The main requirements for the binders are small affinity with dye, easy to release dye gas, and appropriate printing suitability, preservation, and thermal transfer adaptability.
2. The base paper
The base paper for transfer printing should be paper with high-temperature resistance, pressure resistance, seepage prevention, low dye gas permeability, and high tensile strength. The surface smoothness should be high, in order to be able to print fine patterns, technical standards are as follows. Absorbability 40 ~ 100g/m2 air permeability 500 ~ 2000mL/min quantitative 50 ~ 70g/m2 pH value 4.5 ~ 5.5 Sewage is not allowed to use foreign flower paper base paper, Dutch products, the whole series of coniform wood pulp manufacturing, chemical packaging accounted for 50%, mechanical packaging accounted for 50%, this kind of paper at high temperature does not yellow, not brittle. The sulfuric acid method is also used in coniferous wood chemical pulp paper, the paper with good high-temperature resistance, filling formula is as follows (for reference only). Melamine, 0.8% rosin, 2.5% bauxite, 10% talc, 20% in addition to the flower paper base paper with a coating, such as organic silicon, polyvinylic acid, and other substances, can increase the transfer effect.
3. Printing method
Common printing methods are gravure, letterpress, lithography, and screen printing.
4. Transfer printing equipment
There are two general categories. There are two kinds: one is the intermittent type, commonly known as the flat type; The other is the continuous type, mainly the hot roll type. There are two kinds: one is pressure; The other type is decompression, namely, to take the so-called vacuum transfer printing, vacuum transfer printing is most suitable for the deformation of fabrics, wool fabrics, and high-temperature resistant fabrics, such as acrylic bulk fabric, artificial fur, etc. Reduced pressure transfer printing can also make some dispersed dyes resistant to sublimation applied, thus expanding the selection of dyes; On the other hand, can also increase the amount of color and transfer speed.
5. Transfer printing process
Pressure transfer embossing process. Take polyester as an example, the most appropriate process conditions should be at 205℃ under 20 ~ the 30s. However, the effect was poor at 170 ~ 180℃ and 10s. At 180 ~ 190℃ and 15 ~ 10s, only the ring dyeing effect can be achieved. If the temperature is above 230 ~ 240℃ and 40S, the handle will be rough and hard; if the temperature is above 240℃ and 45s, it will be close to melting. Different fabric fiber types, transfer conditions are also different. In addition to temperature and time, transfer printing pressure is also a very important condition. If the pressure is too small, there will be a large gap between the fabric and the paper, and the yarn will be round. In this way, the dye gas molecules will collide with the air in large quantities and escape, resulting in poor effects. At the same time, the dye will also be easy to seep apart, with thick lines and blurred patterns. If the pressure is increased, the yarn can be flattened, the gap between the fabric and the paper is small, and the transfer coloring effect is good, the pattern is clear, the lines are smooth and fine. However, too much pressure will result in deformation, fluffing, and changes in the shape of heavy fabrics, as well as auroras, resulting in rough and hard feel and coloring surface defects.
Digital inkjet heat sublimation transfer printing is to use a digital camera or scanner and professional gallery image digital, through the computer image processing and design, made the required color is gorgeous, exquisite images, and then through a special heat sublimation transfer printing ink inkjet printer ink designed according to the computer images printed on the base of paper, then the image on the transfer paper by baking machine, Lin pan bake machine or printing machine heating, for a few minutes image transfer to the China plate, t-shirts and other souvenirs.
1. Production of sublimation transfer paper
Heat sublimation transfer printing paper production process is similar to digital color inkjet proofing system, which USES computer to thermal transfer, photos and other processing and design, with a digital inkjet printer on the base of paper printing, digital inkjet printer with yellow, taste, green, black and four separate cartridges, so monochromatic image can now be played on the base of paper, also can hit color images. This inkjet printer saves the plate-making process, reduces the production cost, and makes the heat transfer process more simple.
2. Heat transfer on cups, plates, plates and other souvenirs
A digitally controlled mug toaster transfers patterns from sublimation paper to the mug in a matter of minutes. Use the cup toaster to make a beautiful, full-color picture on the cup, the consumption of only a special transfer ink and a special coating of the cup, easy to operate. The design on sublimation transfer paper can be transferred to the plate in a few minutes using an electronically controlled pan toaster. Equipped with special transfer ink, the use of a baking tray machine can be based on a special plate to produce a variety of patterns. The printing machine controlled by electronic digital can transfer the patterns on the eco solvent transfer paper to the porcelain and metal plates in a few minutes. Suitable for making medals, certificates of honor, commemorative plates, portrait porcelain plates.
Card printing has been lithography, embossing, gravure and screen printing, and other printing methods. With the rapid development of high technology, card printing has developed into thermal transfer and sublimation transfer. Heat transfer has been discussed in the previous, now mainly about the application of heat sublimation transfer in card printing. Thermal sublimation transfer printing color card printing now has two forms, one kind is to use a ribbon, the ribbon is yellow, taste, green, black four periods of as a set of coating, each section of equal length and the length of the CARDS, with Beijing leopard chi technology development co., LTD sales PTSO00 smart card equipment as an example, the printing speed 28 s/card, 12 dot/mm print head of the resolution (300 dpi), the ribbon can print 250 CARDS. The card material has PVC and PET, etc. Another is to use color ribbon, color printing process by the green, and yellow, and black four-color printing, respectively, that is, each color printing unit install only one color of ribbon, avoiding the traditional four-color segmentation ribbon inherent ills, reduces the material cost, realize the personalized color, but also greatly extended the life of the print head. For example, the PRINTING resolution of PT6000 smart card equipment sold by Beijing Baoci Technology Development Co., Ltd. is 300DPI, the maximum production speed is 650 CARDS/h (including data transmission time), the printing amount of ribbon is 3300 ~ 10000 CARDS, and the card surface materials are ABS, PC, PET, PVC, etc.