Analysis of production problems of digital printing technology characteristics

Foreword

Traditional textile printing and dyeing is a typical industry with high energy consumption, high noise and high pollution. However, printing and dyeing is an effective means to enrich the variety of textile designs and colors and improve product quality. It is a recognized high value-added industry in the textile industry. After China joined the WTO, global economic integration and the continuous improvement of domestic market consumption levels have led to the continuous influx of high-end and high-priced textiles from developed countries. At the same time, our export opportunities to the international market have also surged: urban consumption has a strong demand for specialty fashion, decoration, The demand for tourist souvenirs is even more urgent. How to use high and new technologies to transform traditional printing and dyeing and solve the “three highs” problem has become an urgent problem for the textile printing and dyeing industry to survive and develop in cities. Through the understanding of the development of digital printing technology at home and abroad in recent years, we now talk about digital printing technology. Here is my personal opinion.

2 Principles and technical characteristics of digital printing

Digital printing is a high-tech technology that integrates machinery, computer electronic information technology and has gradually formed with the continuous development of computer technology. The product first appeared in the mid-1990s and was initially used for rapid printing of advertising paper. Combining it with textile printing and dyeing technology brought a new concept to the textile printing and dyeing industry.

2.1 Principles of digital printing

Digital printing is simply through various digital means. Such as: scanning, digital photos, images or various digital pattern inputs processed by computer After the computer is processed by the computer color separation printing system, the special software driver chip controls the printing system and applies external force to the dye solution, so that the dye solution is sprayed onto the fabric (or medium) through the nozzle, forming a Each color point, digital technology controls the spraying or not spraying of the nozzle, as well as the movement in the xY direction, forming a corresponding and accurate image. Form a variety of high-precision printing products.

2.2 Important technical features of digital printing

2.2.1 Through practical application, feel digital Compared with traditional printing and dyeing processes, printing has obvious advantages in the following aspects:

(1) Because the digital printing process gets rid of the color separation in the production process of traditional printing Many processes such as tracing, filmmaking, and screen making have greatly shortened the production time. The way to accept tricks can be through various advanced means such as CD-ROM and E-mail. Generally, the proofing time does not exceed one working day, while the traditional proofing cycle is generally about a week. In addition, due to the simplification of the process, the cost of proofing is also greatly reduced. Quickly understand customer needs and provideProvide a satisfactory sample.

(2) The design sample can be modified at will on the computer to fully express the designer’s concept. If the customer is not satisfied with the printed sample, the production technicians, designers, and customers can immediately modify it on the computer together, and change the color preparation and pattern. In traditional printing, once the designer’s sample is finalized, it is a very tedious task to modify it. There is a lack of flexibility and quick adaptability to printed patterns and color combinations.

(3) The principle of digital printing technology allows its products to break the limitations of color registration and flower return length of traditional printing and dyeing production, thereby greatly expanding textile pattern design space, improving the quality of the product. If a digital printing machine uses 8 basic colors (quaternary colors and dark blue, light red, light blue, and orange), it can theoretically express 6.77 million colors, especially when printing high-precision patterns such as color gradients and moire. In terms of technology, digital printing has unparalleled advantages.

(4) The traditional water-mixed toner is not used in the high-precision printing process. The use of dyes in the printing process is almost “allocated on demand” by the computer. There is no waste of dye and generation of waste water, and the noise is <58 decibels, thus getting rid of high energy consumption and high pollution and realizing a green production process.

(5) During the digital printing production process, the computer automatically memorizes various color data. During mass production, the color data remains unchanged, ensuring that small samples and large samples, batches and Consistency between batches. In traditional printing, it is difficult to guarantee. This is because the batches of paste mix are different and it is difficult to ensure that the same color is completely reproduced.

(6) Digital printing production truly realizes a small-batch, quick-response production process, and the production batch is not subject to any restrictions. And because the entire digital printing production process is digitally controlled by computers, flexible production can be carried out as needed. For example, if a customer places an order to process 10 square meters of decorative fabric, it only takes 1 to 3.5 hours to deliver it, so it can be delivered immediately. It is simply difficult to achieve using traditional printing.

2.2.2 Current problems in digital printing:

(1) Lack of talents affects the effective use of equipment. To make good use of a digital printing machine, you need to be proficient in computer software applications and machine hardware operations; you need to be familiar with the principles of printing and dyeing; you must also have a certain aesthetic foundation and be able to communicate and organically combine the characteristics of digital printing with the designer’s design ideas.

At present, there is no specialized talent training for digital printing technology in our country + mostly single-tech skills, especially engineering and aestheticsThe integration of academic fields makes the problem more prominent.

(2) High production cost. On the one hand, the localization rate of the main consumables-dye liquor is low and the price is high.

3 Exploration on the application of digital printing technology

In view of the characteristics of digital printing technology, the key to our exploration is how to maximize its strengths and avoid weaknesses, combine it with other printing and dyeing technologies, and form appropriate batch production to meet market demand and achieve optimal economic benefits while ensuring low energy consumption and less pollution.

3.1 Dye liquor and standard hue selection

The price of dye liquor is currently leading to the cost of digital printing A major factor in the high. Reasonable selection of dye liquor configuration, that is, color management system, is very critical to make it economical, practical and effective. Digital printing machines have different technologies and production concepts from traditional printing. The choice of dye solution hue is one of the most divergent issues in digital printing technology. Each production company has a different understanding of the issue of whether to use standard printing four primary color dye solutions or choose pre-blended “spot color” dye solutions.

3.1.1 The advantages of dye liquor are:

(1) The color accuracy is quite high. For printing and dyeing enterprises, the operating habits are Similar and easy to accept.

(2) The requirements for the jet accuracy of digital printing machines are low. For light colors, as long as there is software support. The injection dye volume can be reduced to 5ml/m.

(3) Due to the low accuracy, the jet printing speed may be increased.

3.1.2 The disadvantages are:

It requires personnel who are proficient in color mixing: it is necessary to reserve many varieties of dyes like printing and dyeing factories, and due to the special requirements of jet printing dyes (such as cleaning Degree) and color matching accuracy requirements may require a color measurement and color matching system and an automatic dye color matching system. The above systems are relatively expensive.

Referring to the four primary colors or similar limited primary color combinations for printing, the advantages are:

(1) It can reduce the reserve of dyes, Just prepare a few dye solutions.

(2) There is no need to equip expensive color measurement and color matching and dye blending systems, and there is no need to recruit professional color matching personnel. Color analysis can be automatically performed by computer software, and the dye box can be inserted into the digital jet printing machine for use.

The disadvantages are:

(1) It requires special color analysis software, usually called RIP (rasterizer), and the compilation level of RIP software has a huge impact on color accuracy and printing speed. Have a greater impact.

(2) There are many dye liquor manufacturers, resulting in many different software and hardware combinations, and there is a lack of unified standards. If the type of equipment is changed, or multiple types of equipment are shared, corresponding dye liquors must be equipped and cannot be mixed, causing inconvenience in use.

(3) The jet printing machine has high requirements for jet accuracy. Generally requires 360~720DPI.

(4) Operating habits vary greatly and require an adaptation process. Through joint discussions with equipment manufacturers, the use of limited primary color combinations is currently a more reasonable choice technically and economically. It is more suitable to choose 8 to 10 dye liquor combinations. On the one hand, it has a relatively small number of combinations, which is convenient for dye liquor storage; on the other hand, it adds orange, dark blue, light blue, light red and other spot colors on the basis of the four primary colors, which increases the color gamut and is conducive to accuracy. Attention to color. Choosing a good software management system can meet the needs of color fidelity economically.

3.2 Processing technology selection

Digital printing equipment only solves the printing process. For different fiber fabrics, reasonable process flow and process parameters must be selected. This is the prerequisite for achieving mass production and ensuring product quality. In view of the current situation of Beijing’s textile industry, it is more economical and appropriate to choose bleached fabrics that have been treated before traditional printing and dyeing as gray fabrics, which avoids the possible pollution caused by desizing and shortens the processing process. According to the different dyeing mechanisms of different fiber dyes, different processes are selected:

(1) Polyester fabrics:

Fabric padding and sizing-disperse dye printing-drying-steaming Dissolve (180℃, 8 minutes) into water Wash and dry

Disperse dye printing paper-fabric-transfer printing (170-190℃, 3020s)

(2) Cellulose fiber fabric:

Fabric dip Roll sizing-active Dye printing-drying-steaming (102℃, 8 minutes)-washing-drying {special dye printing paper-fabric padding and sizing (special finishing agent)-transfer printing (180-190℃, 3020s)

(3) Silk, wool, brocade Fabric:

Fabric padding and sizing-acid dye printing (silk fabrics can be reactive dyes)-drying-steaming (102°C, 30 minutes)-washing-drying silk and wool fabrics can also be realized at present. Transfer printing, but this subject has not yet been tested and applied.

During traditional printing, the printing paste includes dyes, pastes and various color development, color fixation and other additives. The viscosity is high and may be suitable for spraying. Print head. In digital printing, various additives and anti-seepage agents are mixed, the material is padded and sized first, and the dye is sprayed from the nozzle. Fabrics with different fibers, different tissue specifications, and different patterns require different sizing formulas. At present, there is no mature technology and formula at home and abroad. From the printing effect, generally exceptFor acid dyes, use low viscosity paste plus additives for sizing. For other dyes, it is better to use medium viscosity paste plus additives for one hour. Different fibers use different additives, mainly the amount of urea, acid, and alkali. The printing environment temperature should be kept at 15~33℃ and the humidity at 35~80%. The dry northern climate can easily cause the dye solution to block the nozzle. Special finishing agents and dyes for fiber rope fiber transfer printing are new research results of our city’s Textile Science Institute. They already have the conditions for industrial production and can be used in digital printing, but attention must be paid to matching the equipment and dye liquor production.

4 Conclusion

The high-tech, high-efficiency, high-quality, pollution-free and other superior properties of the digital printing technology production process, coupled with reasonable technology and equipment configuration, are enough to have a broad market space and sufficient profits in metropolitan areas . It will undoubtedly provide a new model for transforming and upgrading the traditional textile industry with high and new technologies.