The hottest packaging industry appreciates the EB

2022-08-07
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The packaging industry appreciates the EB curing potential (Part 1)

the packaging industry is an enduring industry in the world's economically developed countries. At present, flexible packaging is the fastest growing field in the 2nd brush packaging, of which food packaging printing accounts for a large share. Typical flexible packaging is usually made of multi-layer polymer materials through lamination, and sometimes vacuum metal coating is also involved. As far as food packaging is concerned, the packaging materials shall not have unpleasant smell and heterogeneous taste. In a word, there are different requirements for different applications, reflecting the complexity of packaging structure and the diversity of packaging products. It is under this background that electron beam curing technology is introduced into the packaging industry

I. EB curing and EB device

1 Electron beam curing

electron beam curing is a process of rapidly changing liquid into solid at room temperature by using electron beam as an irradiation energy to conduct radiation chemical reaction with active liquid chemical formula. Compared with traditional thermal curing, ultraviolet (UV) curing is unique (Table 1). The ultra-low energy EB device (30~150kev) appearing in the market since this century has made the packaging industry deeply feel the application potential of EB curing

2. EB device

eb device, also known as electron accelerator, is a device that generates high-speed electron beam by accelerating electrons with the help of electric field. There are two types of electron accelerators that can be used in the packaging industry: scanning type and electronic curtain type

II. Examples of the application of low-energy electron accelerators in the packaging industry

the emergence of a new generation of low-energy electron accelerators provides an unprecedented opportunity for the packaging industry, especially for the technological transformation and technological innovation of flexible packaging process:

1 EB curing ink

eb curing ink plays an important decorative effect in graphic printing on many flexible packaging materials. At present, it has made remarkable applications in rotary offset printing and satellite flexographic printing (CI printing with common embossing Center)

(1) web offset

EB curing ink for rotary offset printing has been used in some economically developed countries (such as Europe and the United States) for paperboard (record packaging bags and food containers) and polyethylene (PE) coated paperboard (liquid food containers). At present, rotary offset printing inks are mainly used for food packaging and non food packaging. The curing of wet press wet offset printing inks is realized in six color to eight color printing machines. In recent twoorthree years, it has also begun to increase in flexible packaging. Usually, wet ink is coated with a layer of varnish, and both are cured at one time by electron beam

in some cases, EB laminating adhesive is also cured once by electron beam together with offset printing ink and finishing paint. In addition, the rotary printing machine can adapt to different outer box packaging, which provides the possibility for the development of flexible materials short edition live economic printing. Because EB curing ink and varnish do not contain photoinitiator, it is often used to dry the printing of packaging materials such as food by electron beam irradiation, or you can learn a lot. Fig. 2 shows an eight color rotary offset press equipped with a gloss coating device and an EB curing device. The low-energy electron accelerator in EB curing device is specially designed for the printing machine

EB curing packaging materials commonly used in flexible packaging are listed as follows:

- pet/aluminum metal film/pe pre laminated structural packaging materials. Printing ink on PET film surface; Then EB curing varnish is applied to the ink by dongjinshi, vice chairman of plastic recycling Professional Committee of China Plastics Association, and the offset printing ink and varnish are cured by electron beam. The packaging material structure is mainly used for vertical bags for packaging dry food and packaging liquid

- pe/paper/aluminum metal film/pe pre laminated structural packaging material. PE surface is printed and then coated with gloss coating, and electron beam curing offset printing ink and gloss coating. The packaging with this structure is mostly used for confectionery

- pet/ink printing/eb curing laminated adhesive/pe composite structure packaging material. PET packaging machine 'target=_ Blank> the transparent film is printed on the back and then laminated on PE. Electron beam curing offset printing ink and laminating adhesive. This process not only provides instant curing for EB curing laminated adhesive, but also provides assembly line processing, which helps to further reduce the cost. Packaging materials with this structure are often used for meat and cheese packaging

- pet/eb curing laminated adhesive/aluminum metal film/resin/low-density PE pre laminated structural material. PET packaging machine 'target=_ Blank> the transparent film is printed on the back and laminated on the aluminum metal film. Electron beam curing offset printing ink and laminating adhesive

electron beam curing process generally does not have much impact on the properties of most commonly used film substrates in flexible packaging. All these applications require further operations such as filling, heat sealing and ironing. At present, it has realized the practical application of six to eight color inks and varnishes, as well as the curing speed of m/min electron beam

(2) flexographic printing

most flexographic printing machines traditionally use water-based ink or solvent based ink. In recent years, due to increasingly stringent environmental regulations on VOC emissions, and the traditional ink heating and drying limit the processing speed, in addition, heating may damage some heat sensitive substrate. So flexographic printing turned to UV curing in the early 1990s. However, UV curing flexographic printing has not broken through the most important field of food packaging in the packaging industry, and still adheres to the label Outdoor packaging bags, folding boxes and other printing markets

obviously, EB curing has the hope that the remaining funds will be invested in the production intelligent upgrading and transformation and the construction project of technology R & D center, hoping to make up for the shortage of UV curing. In recent years, the development of EB curing flexographic printing ink, in flexographic printing, the EB curing ink system can be transferred from the printing plate to the substrate to transfer the liquid to the semi-solid state instantaneously. This chromatic concept of EB curing wet press ink, called wetflex, seems to be the end solution to the problems of UV curing flexographic printing. Various colors are stacked layer by layer at the multi-point printing station around the CI embossing cylinder. Finally, the multi-layer chromatic text images are instantaneously solidified by the electron beam through the low-energy electron accelerator at the end of the CI flexographic press. This 100% solid EB ink significantly reduces dot enlargement and provides a printing effect that is not significantly different from the original dot. More importantly, EB curing flexographic printing uses a low-energy electron accelerator to replace all the UV light source intermediate drying stations around the CI Drum, or cancels the post large-scale heating dryer used for the over plate drying of solvent based ink and water-based ink thick ink, greatly simplifying the process of traditional flexographic printing. At the same time, the EB curing process does not generate heat, so the cooling problem of CI drum can be eliminated. The EB curing flexographic ink contains no photoinitiator, which greatly reduces the odor of the curing ink and improves the printing speed. It will undoubtedly be of great use in food packaging in the future

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