The hottest textile printing industry will take th

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Textile printing industry will take the environmental protection road of cold transfer printing

textile printing and dyeing industry is China's traditional advantageous industry. With the continuous progress of technological transformation in recent years, export trade continues to expand. According to the 2007 printing and dyeing industry research report, from 2000 to 2005, the export volume of six categories of printing and dyeing products increased from 3.8 billion meters to 10.37 billion meters, with an average growth rate of 82%; The export value increased from 2.8 billion US dollars to 8.48 billion US dollars. However, with the increase of total exports, the crisis of textile printing and dyeing industry also followed. February 18, 2006 The European Union has adopted a new chemical regulation, the regulation on registration, evaluation and licensing of chemicals (reach). After the implementation of the regulation, about 30000 chemical products in the EU market and their downstream textile products will be included in the three links of registration, evaluation and licensing to implement safety monitoring. Many chemicals involved in traditional printing and dyeing are blocked out of the European market with high green barriers, which has a huge negative impact on China's textile printing and dyeing industry. The eco label specification with higher requirements clearly points out that the implementation of the specification aims to reduce the pollution of water environment caused by key processing processes in the whole textile production chain (including fiber production, spinning, weaving, pre-treatment of printing and dyeing, printing and dyeing, post-treatment, and garment production)

in view of the severe situation of raising the threshold of the international market, the development of China's printing and dyeing industry must pay attention to environmental protection, improve the efficiency of water resources utilization, vigorously promote cleaner production, and develop and promote all kinds of new technologies and products that reduce pollution, save energy, and are conducive to health with the concept of ecological environmental protection. Due to the uniqueness of its process, the emerging cold transfer printing technology has significant advantages in energy saving, consumption reduction, pollution discharge and improving the added value of textile printing. It can produce high-grade textile printing products and ecological textiles that can unblock the European continent

II. Transfer printing process characteristics

transfer printing was invented years ago in the 1950s. It first uses printing methods to print the patterns to be printed on specially treated paper with appropriate dye ink, and then makes transfer printing paper, referred to as transfer paper. After that, one side of the ink on the transfer paper is closely connected with the printed fabric, and the dye is sublimated through heat and pressure, that is, the sublimation method, so that the ink layer is stripped from the paper, and the pattern on the transfer paper is transferred to the fabric; However, this heat transfer printing technology can only be used on polyester fabrics. Due to the advantages of simple transfer printing method, convenient operation, high genuine rate of finished products, low equipment investment cost and so on. However, this sublimation transfer printing (hot pressing) has its shortcomings and limitations. For example, the selection of dyes is very narrow. Many dyes that must be used in sublimation transfer printing have substances that can decompose into carcinogenic aromatic amines when transferred. In the latest document issued by the international textile ecological research and Inspection Association on February 9, 2002, there are 7 kinds of carcinogenic dyes, of which disperse dyes account for two kinds, disperse blue C11 and disperse yellow CL3; The 19 sensitizing dyes listed are all disperse dyes that can be used in sublimation transfer method. Because the dyes transferred from the transfer paper to the fabric can not be absorbed into the interior of the fiber in the general sublimation transfer printing, there are always some dyes left on the surface of the fabric, which is the reason for the poor fastness of the transfer printed fabric. Secondly, because sublimation heat transfer printing inks are prepared with solvents, there are great difficulties in the recycling of waste transfer paper, and the production of transfer paper has serious environmental pollution. Due to the above factors, the entire production process of printing transfer paper and transfer to fabric cannot meet the Oeko tex standard necessary for the market of developed countries, resulting in the lack of competitiveness of products and the inability to break through the green barrier of the market

cold transfer printing process, it is to use the printing method to print the appropriate dye ink on the special paper to print the pattern or text to be printed into a kind of transfer printing paper. The fabric after alkali rolling and the transfer paper enter the transfer roller at the same time. The side with dye ink on the transfer printing paper is close to the printed fabric, and the dye ink is separated and stripped from the paper through pressure, so as to transfer the patterns or words on the transfer printing paper to the fabric. Therefore, cold transfer printing is also known as wet transfer printing. Cold transfer printing has significant advantages in the printing of natural fiber fabrics such as cotton, wool and silk. For natural fiber fabrics such as cotton, wool and silk, transfer printing cannot be realized by sublimation because water-soluble dyes such as reactive dyes or weak acid dyes are commonly used. In order to inspect and test the cold transfer printing process, the advantages are: the pattern design is easy to change; Colors are diversified, including halftone (color between light and dark) and light color; Basic colors (patterns) strongly outlined; High uniformity; It is a technology that can repeatedly produce completely consistent products; Short process is an economical method; There are almost no defective products. The pattern of cold transfer printing is lifelike, artistic and simple, and its process is energy-saving and environmental protection, which fully meets the requirements of the technical policy for the prevention and control of wastewater pollution in the printing and dyeing industry

III. outstanding performance of cold transfer printing process in energy saving and environmental protection

during the Tenth Five Year Plan period, the development of China's printing and dyeing industry has made great progress. However, in the face of the state's clear proposal during the Eleventh Five Year Plan period to take resource conservation as the basic national policy, to develop a circular economy, protect the ecological environment, and speed up the construction of a resource-saving and environment-friendly society, the printing and dyeing industry is facing a severe situation in energy conservation and consumption reduction and environmental protection. In the process of printing and dyeing, water, as the medium participating in the whole chemical processing process, has large consumption and discharge capacity, and the concentration of pollutants in the wastewater is high and the chromaticity is deep. According to the statistics of the State Environmental Protection Administration, the water consumption per unit product of printing and dyeing enterprises is generally about three times that of developed countries, while the water reuse rate is only 7%; The total amount of wastewater discharged from the printing and dyeing industry ranks fifth in the total amount of manufacturing industry in China, accounting for 80% of the total amount of textile wastewater discharged in China In the pre-treatment process of printing and dyeing, a certain amount of alkaline substances and impurities (pectin, wax, size, grease, etc.) contained in fibers or fabrics are mainly discharged. This part of wastewater accounts for about 50% - 60% of the total amount of printing and dyeing wastewater that cooperates with customers to optimize the design of thin-walled molds. Dyes, surfactants, slurries, phosphates, nitrides, organic chlorides and heavy metals in printing and dyeing wastewater cause great pollution to the water quality. Among them, phosphates seriously eutrophic the water body, reduce the dissolved oxygen in the water body, and fish and shrimp disappear. A large number of surfactants make the water surface foam obvious, and a large number of residual dyes in the water body significantly deepen the color of the water body. Secondly, the textile industry also has the problem of high energy consumption. For example, textile machinery and chemical fiber machinery are called electric tigers. The operating efficiency of the motor drive system used by China's textile enterprises as a whole is nearly 20% lower than that of foreign countries, and the power consumption is very prominent

during the Eleventh Five Year Plan period, the state clearly proposed to take resource conservation as the basic national policy, and the cold transfer printing process should achieve the goals of energy conservation, consumption reduction and low sewage discharge in production through technological means in all technical processes

in terms of water consumption, in the traditional printing process, the main water consumption process is in the washing stage. Based on a 1.8m3/single tank eight tank washing machine, the total water capacity of the eight tanks is 14.4 m3, and the overflow (calculated according to an inch of pipe) is flat. Next, let's understand that the common requirements of a lower tension machine that meets the standards of the light industry are 0.7 m3/single tank per hour. The water washing speed of printed cloth is calculated as 20m/min. The water consumption for producing 10000 meters of cotton cloth is about 46.6 m3. Cold transfer printing has good printing adaptability and transferability through the use of transfer printing paper coated with separator. At the same time, through the use of special paste, the cold transfer printing paste has sufficient permeability, good dye transmissibility, high color fastness and excellent characteristics, so that it uses less water and has less pollution in the water washing process. The water washing machine only needs to use five tanks for washing, so the water consumption for the production of 10000 meters of figured cloth is 29.1 m3, so the water consumption can be saved by ~ 63%

in terms of energy consumption, if the traditional printing process uses a drying and setting machine, and eight section ovens are equipped with 16 sets of 7.5 kW motors and 1 set of 18.5 kW motors, the power consumption per hour will reach 138.5 kW. It takes 5.5 hours for the thick fabric to be dried and finalized at 30m/min and 10000 meters. The power consumption is 761.75 kW. The speed of conventional fabric is 50m/min, and it takes 3.3 hours for 10000 meters. The power consumption is 457.05 kW. If the steam setting machine is used, 15 tons of coal will be required in 16 hours based on the calculation of 4 tons of boiler. Two 22 kW motors, with a 16 hour power consumption of 704 kW. For the cold transfer printing process, in addition to a very small amount of heating, no steam is needed, so the use of steam saves about 99.5%. Cold transfer printing adopts cold stack fixation in the fixation process. Compared with the traditional printing process, the overall operation of the cold transfer printing process saves ~ 38% of power consumption

in terms of sewage discharge, generally, the COD of washing waste liquid after pretreatment in printing and dyeing plants is high, and the COD of dyeing waste liquid is high, and the chromaticity is also high This is mainly dye. When dyeing dark varieties, the chroma of waste liquid is as high as 3000 ~ 4000 (Times). In the process of cold transfer printing, the transfer rate of dye and ink can be more than 90% in the process of transfer printing. At the same time, due to the advanced printing paste and equipment technical conditions, not only realistic patterns and patterns can be obtained, but also high fixation rate, so that the pollution caused by water washing is far lower than that of traditional printing process

to sum up, the overall level of resource consumption in printing production with the new cold transfer printing technology is much less than that of the traditional printing process. It is estimated that each million meters of fabric printing production capacity can save 600000 ~ 700000 yuan per year; Textile printing production per million meters can reduce the total discharge of wastewater by 15000 tons/year, save dyes by ~ 26%, and reduce the non-ferrous pollution in wastewater by 65%. It has obvious characteristics of short process route, energy saving and consumption reduction, and pollutant emission reduction

IV. summary

the textile industry is a traditional pillar industry of China's national economy and one of the industries with obvious international competitive advantages. Since China's entry into the WTO, China's textile and clothing industry has shown unprecedented rapid development, but at the same time, there are also problems such as high energy consumption, low resource utilization, strict sewage discharge, and heavy participation of SAMPE Beijing Branch members or groups of more than 3 people. While people pay more and more attention to the environment, the eyes of the printing and dyeing industry are also paying attention to the emerging cold transfer printing process. Shanghai Changsheng textile products Co., Ltd. spent three years and invested millions to launch the cold transfer printing process and cold transfer equipment. It has been awarded seven invention patents and four utility patents by the state. The products produced by this process have broken through the EU green barrier and gone global. Changsheng company is willing to provide the national printing and dyeing industry with the most advanced fabric printing technology with low energy consumption and low pollution at room temperature, cold transfer printing and corresponding supporting equipment under the current financial storm and the sharp decline in the export volume of traditional textiles. This process fully improves the dye utilization rate, and the treated fabric feels plump and thick, which truly reflects the intrinsic value of cotton. It is suitable for different fibers, different tissues and different specifications, such as silk, nylon, knitting and woven products, whose quality meets or exceeds the relevant technical quality standards

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