The method of printing on fabrics using sublimation transfer printing paper is also called vapor phase thermal transfer printing. The basic production method of transfer printing is to first make suitable dyes into ink, then print it into floral paper, and then overlap the floral paper with the fabric and heat and pressurize or reduce the pressure. The dye on the paper becomes a gas phase state and is sublimated for transfer printing. onto the fabric.

1. Dye-sublimation transfer ink

Dye-sublimation transfer ink is mainly composed of heat-lift dyes. The dyes used for sublimation transfer printing can be selected according to the following conditions: The molecular weight of the dye is generally not suitable. More than 350; There is intermolecular force between the dye gas and the fiber and can diffuse into the fiber; The dye sublimation temperature is more suitable below 200°C; The color fastness of the dye transferred to the fiber meets the wearing requirements; The color fastness on the fiber The color is bright and bright; the dye has no affinity with the base paper. Commonly used transfer printing dyes include anthraquinone dyes, azo dyes, cationic dyes, etc. Commonly used resins for binders are low-viscosity ethyl cellulose, ethyl hydroxyethyl cellulose (EHEC), long oil modified alkyd resin, etc. Commonly used solvents include turpentine, terpineol, high boiling point alkanols, aralkanes, Cellosolve, etc., and a small amount of other additives. The main requirements for the binder are that it has low affinity with dyes, is easy to release dye gas, and has suitable printing suitability, preservation and heat transfer adaptability.

2. Thermal transfer paper

The base paper used for foreign decorative paper is produced in the Netherlands and is entirely made of softwood pulp, of which chemical packaging accounts for 50% and mechanical packaging accounts for 50%. This kind of paper does not turn yellow or become brittle at high temperatures.

Sulfite-based softwood chemical pulp paper is also available. This paper has good high-temperature resistance with fillers. The filler formula is as follows (for reference only).

Melamine 0.8%

rosin 2.5%

alumina 10%

talcum powder 20%

In addition, coatings such as silicone, polyethylene acid and other substances are added to the base paper to increase the transfer effect.

3. Printing methods

There are four commonly used printing methods: gravure printing, embossed printing, flat printing and screen printing.

4. Transfer printing equipment

Generally, it can be divided into two categories. There are two types: one is intermittent type, generally called flat type; the other is continuous type, mainly hot roller type. The two categories are: one is pressurized; the other is decompressed, which is the so-called vacuum transfer printing that uses air extraction. Decompressed transfer printing is most suitable for deformed fabrics, raised fabrics and fabrics that are not resistant to high temperatures. Such as acrylic expanded fabric, artificial fur, etc. Pressure-reduced transfer printing can also make use of some disperse dyes that are not resistant to sublimation, thereby expanding the selection of dyes; on the other hand, it can also increase the color yield and transfer speed.

5. Transfer printing process

Pressurized transfer embossing process. Taking polyester as an example, the most suitable process conditions should be 20 to 30 seconds at 205°C. However, the effect is not good at 170~180℃ and 10s. At 180~190℃ and 15~10s, only the ring dyeing effect can be achieved. If the temperature is 230~240℃ and above 40s, it will feel rough and hard; if the temperature is 240℃ and above 45s, it will be close to melting. Different types of fabric fibers require different transfer conditions.

In addition to temperature and time, pressure during transfer printing is also a very important condition. If the pressure is too small, the gap between the fabric and the decorative paper will be large and the yarn will be round. In this way, a large number of dye gas molecules will collide with the air and escape, resulting in poor effect. At the same time, the dye will easily seep out, resulting in thick lines and blurred patterns. If the pressure is increased, the yarn can become flat, the gap between the fabric and the flower paper is small, and the transfer coloring effect is good, the pattern is clear, and the lines are smooth and fine. However, excessive pressure will cause deformation, fluffing, and changes in the shape of heavy fabrics, as well as aurora, which will bring about rough texture and coloring surface defects.

Types of clothing heat transfer printing technology

There are many types of clothing heat transfer printing technology, and there are two main categories of common heat transfer printing methods:

1. Sublimation heat transfer.

2. Thermal transfer printing

Sublimation thermal transfer

Simply put, disperse dye (or sublimation ink) is printed in advance by a machine ( or print) onto a specific paper, and then use this paper to use high temperature and high pressure to transfer the pattern on the paper to the fabric that needs to be printed, completing the entire transfer printing process.

However, with the development of science and technology, the industry has made some refinements, allowing transfer printing methods to emerge in endlessly. The most prominent thing is that paper is also used as the transfer printing carrier, but the printing method is gravure printing. Machine printing disperse dyes are the mainstream.

According to the transfer printing market demand, the most versatile printing methods are:

(1) Gravure printing machine prints disperse dyes. The advantages are: low cost of printing paper and delicate pattern expression. , strong sense of layering and full flower pattern. Suitable for mass transfer printing production. The disadvantages are: high plate making costs and insufficient competitiveness for small batches of personalized products.

(2) Use an offset printing machine to print offset sublimation ink. Use a printer to print the sublimation ink. After it dries naturally, use this decal paper to transfer it to the fabric that needs to be printed. Advantages: Because it uses ps printing, the printing fee is low, and the printing fee cost is also low, which is suitable for small batch product printing. Disadvantages: The color depth after printing is difficult to control well. If you want to do heat transfer printing on clothing, you have to think about it, because any piece of clothing is made of at least two pieces of cloth. Just imagine: the front and back of the clothing How can I sell this piece of clothing when the colors are so different? How to wear it?

(3) Digital thermal transfer printing, advantages: the pattern expression is more delicate than any other transfer printing, the sense of layering is very strong, the pattern is extremely full, and because of the plateless printing, other printing methods are completely excluded The resulting disadvantages include inaccurate color registration or blockage. Disadvantages: Although there is no printing fee, the cost of printing ink and paper is high. So far, it is only suitable for transfer printing of small batches of personalized products.

(4) Silk screen sublimation ink. This transfer printing method has low plate making costs and sublimation ink is not expensive. However, because the printing plate is a screen version, the edges of the pattern produce burrs, which is not suitable for characters. Class, landscape and other delicate pattern printing.

Thermal transfer printing

Different from the sublimation heat transfer printing method, the printing material does not produce sublimation (vaporization) like sublimation dyes, and the printing material does not print at high temperatures. The high pressure causes the slurry to penetrate into the fabric fibers. Although it can also be pressed with a transfer machine, what is "printed" on the surface of the clothing is like a layer of "plaster" that adheres to the surface of the clothing.

Its main features are: the base material used is mostly PET sheet. After printing patterns of various colors on the PET sheet, hot melt adhesive must be coated on the back of the pattern. This hot melt adhesive firmly combines the pattern with the clothing, peels off the PET waste film, and completes the heat transfer process.

Advantages of heat transfer printing: low plate making cost, full pattern levels, and beautiful color. Disadvantages: The air permeability is poor after being transferred to clothing, and the feel is not as soft as sublimation heat transfer. Digital inkjet sublimation transfer uses a digital camera or scanner and a professional library to digitize the image, and performs image processing and design on a computer to produce the required colorful and delicate images, and then uses a dedicated sublimation printer to An inkjet printer that transfers ink prints the ink on the base paper according to the image designed by the computer, and then heats the image on the transfer paper through a cup baking machine, baking pan machine or baking machine. The image is transferred to the porcelain in a few minutes. on plates, cultural shirts and other souvenirs.

1. Production of sublimation transfer paper

The production process of sublimation transfer paper is similar to the digital color inkjet proofing system, that is, using a computer to heat transfer the image Process and design documents, photos, etc., and use a digital inkjet printer to print on the base paper. The digital inkjet printer is equipped with four independent ink cartridges of yellow, magenta, cyan, and black, so a monochrome image can be printed on the base paper. Color images can also be printed. This inkjet printer saves the plate making process, reduces production costs, and makes the thermal transfer process simpler.

2. Heat transfer patterns on cups, plates, boards and other souvenirs

Using an electronic digitally controlled cup baking machine, the pattern on the heat sublimation transfer paper can be printed in a few minutes Transfer to the cup within a matter of time. Use a cup baking machine to create a beautiful, full-color picture on a cup. All you need is special transfer ink and a cup with a special coating. The operation is quick and easy.

Using an electronic digitally controlled baking pan machine, the pattern on the sublimation transfer paper can be transferred to the plate in a few minutes. Equipped with special transfer ink, you can use the baking pan machine to bake various patterns on special plates.

The pattern on the sublimation transfer printing paper can be transferred to porcelain and metal plates in a few minutes using an electronic digitally controlled printing machine. Suitable for making medals, certificates of honor, commemorative plaques, and portrait porcelain plates.

Smart card dye sublimation penetration color imaging technology

Card printing has earlier included flat printing, embossed printing, gravure printing and screen printing. With the rapid development of high technology, With the development, card printing has developed into thermal transfer printing and sublimation transfer printing. Thermal transfer printing has been discussed previously, focusing on the application of thermal sublimation transfer printing in card printing.

There are two forms of color sublimation transfer card printing. One is to use a ribbon. The ribbon is divided into four sections: yellow, magenta, cyan and black. Each section is coated in a group. The length is equal to the length of the card. Taking the PTSO00 smart card equipment sold by Beijing Baochi Technology Development Co., Ltd. as an example, the printing speed is 28s/card, the print head resolution is 12dot/mm (300dpi), and the ribbon can print 250 cards. Card surface materials include PVC and PET.

Another method is to use color separation ribbons. The color printing process consists of four color ribbons: cyan, magenta, yellow, and black. That is, each color printing unit only installs one color ribbon, thereby avoiding It overcomes the inherent disadvantages of the traditional four-color segmented ribbons, reduces consumable costs, realizes color personalization, and greatly extends the life of the print head. For example, the PT6000 smart card equipment sold by Beijing Baochi Technology Development Co., Ltd. has a printing resolution of 300dpi, a maximum production speed of 650 cards/h (including data transmission time), a ribbon that can print 3,300 to 10,000 cards, and a card surface material of ABS. , PC, PET, PVC, etc.