Discussion on the selection of gravure printing in

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Discussion on the selection of gravure printing ink from the perspective of raw material procurement

raw material procurement is an important link for enterprises to achieve economic benefits, and the quality and technical performance of raw materials are also the key links affecting product quality. In the flexible packaging printing raw materials, the ink quality and technology are based on the mature fire-resistant B1 polyurethane material technology, and the technical performance is the most important factor affecting the product quality of packaging materials. As a technician in charge of raw material procurement in flexible packaging enterprises, the author plans to discuss the selection of gravure printing ink from the perspective of procurement, including its applicability and economy, with colleagues in order to attract jade

I. selection of suppliers

the selection of upstream supply enterprises should be based on the requirements of the internationally accepted ISO9001 quality assurance system, first try the ink, and draw a conclusion according to the opinions of technology, production personnel and customers. If the requirements are met, the supplier will be organized to play the role of haopin Shandong, Shandong Industrial cloud innovation service platform and other technicians, and the customer representatives will be invited to make a field visit to a number of ink production enterprises, including the production site, product performance, R & D strength and customer satisfaction. Because the printability of ink is related to ambient temperature and humidity, the choice of ink supply enterprises should also consider the climate gap, giving priority to enterprises in the nearest region. According to the principles of "quality first, price comparison procurement" and "equal quality, price and service", at least two ink manufacturers are selected to be included in the "list of qualified raw material suppliers" to realize fixed-point procurement. The inspection of qualified suppliers should be carried out every two years, mainly to conduct a comprehensive review of product quality, technical performance, price, delivery date, technical services and customer satisfaction. The review panel is composed of technology, production, supply, sales, customer representatives and senior management. Especially pay attention to the technical service and communication ability of suppliers, actively participate in solving printing quality problems, and be able to bear due responsibilities. We should pay attention to the importance of ink quality in packaging and printing, strengthen the management of ink production enterprises as first-class upstream customers, and realize "win-win development" in the value chain

II. Applicability of inks

when purchasing inks, we should first consider the applicability of inks. The applicability of ink should be based on the following aspects:

1 Printing substrate

printing substrates with different resins should choose inks with different resin systems. At present, the commonly used printing substrates include BOPP film, BOPET film, BOPA film, PE film, etc. According to the principle of "similarity and compatibility", only when the matrix resin is similar or similar, the printing substrate and ink will have good adhesion. In the ink system, the binder resin plays a key role in adhesion. Currently developed gravure printing ink According to the solvent, it can be divided into benzene solvent ink, alcohol solvent ink, water solvent ink, etc. It can be divided into chlorinated polypropylene ink, polyurethane ink, polyamide ink, etc. according to the resin of connecting material. Chlorinated polypropylene ink is suitable for inner printing of BOPP film; Polyurethane ink is suitable for the printing of BOPET film and BOPA film, and can be boiled at high temperature and in water; Polyamide ink is suitable for surface printing of BOPP film and PE film

2. Printing process conditions

printing process conditions include printing speed (linear speed), drying capacity, plate roller performance, gravure printing method (surface printing, internal printing), printing color number, printing sequence, ambient temperature, humidity, etc. The process conditions directly affect the transfer rate and drying speed of ink, so we should choose ink reasonably and economically according to the process conditions. For example, when the humidity on the production site is high and the printing speed is high, high-grade inks with high transfer rate and fast drying speed should be selected to prevent adhesion of the film after printing. Under the process conditions of dry air and fast printing speed, choose the ink with high viscosity and antistatic agent to avoid the quality problems caused by static electricity

3. Printing effect

printing effect includes the hue, gloss, transparency, concealment, layering, overprint accuracy, etc. Different ink manufacturers have certain differences in hue, solid content, viscosity, gloss, hierarchical expressiveness, etc., and even the inks produced by the same manufacturer and different batches are not the same. Therefore, after making the same product and later when he is more and more familiar with this kind of material, after the printed sample is approved by the customer, he should purchase enough inks of the same batch at one time as far as possible to ensure the consistency with the sample

4. Post press process conditions

after printing, plastic film also goes through extrusion compounding, dry compounding, vacuum aluminizing, slitting, bag making and other processes. When customers use it, they even need to be treated with high-temperature cooking, boiling, freezing, sterilization and disinfection. Therefore, we should choose ink according to the post press process conditions and use conditions of packaging materials. For example, in dry compounding, the adaptability of printing ink and adhesive should be considered without affecting the peel strength of the compounded product. In bag making, high-temperature cooking, boiling, freezing and other treatments, we should consider the high and low temperature resistance of surface printing ink to prevent ink film separation, discoloration and other problems

5. Customer's conditions of use

ink is an organic system composed of pigments, additives, binders, fillers, solvents and other chemical substances. After printing, an ink film is formed and attached to the plastic substrate. As a packaging material for various products, it not only plays an eye-catching marketing role, but also plays a role in ensuring product quality and protecting consumers' life safety. Therefore, the selection of ink should first consider the hygiene, safety and tasteless of the ink, and its resistance to meet the customer's use conditions. The ink resistance includes light resistance, heat resistance, grease resistance, chemical corrosion resistance and good compatibility with the packaged products. Surface printing inks should be resistant to friction, oxidation, water and light, and have certain antistatic properties. The additives added to meet the resistance of ink should be hygienic and non-toxic; Unnecessary fillers are not required

III. economy of ink

the economy of ink includes not only the purchase price, but also the purchase quantity. The purchase amount of ink should be calculated according to the material demand provided by the production department and the raw material consumption quota prepared by the technical department. While achieving economic procurement as much as possible, we should also reduce the use cost according to the actual production situation. Because ink, especially toner ink, is different from other raw materials, once it is surplus, it is very difficult to use it again, so it has to be discarded, resulting in waste. To achieve "zero inventory" approach, not only reduce the occupation of funds, but also can choose the bias of primary color ink according to the requirements of customers, so as to ensure the color consistency of prints. For example, the primary color red has two kinds: bright red and purple; The primary blue is divided into sky blue and purple; The primary color yellow is divided into green and red. When the temperature and humidity of the on-site environment cannot be controlled artificially, the ink containing different additives should be selected according to different on-site environment to reduce the increase of use cost caused by temporary addition in the printing process. The ink is required to have a certain anti-static performance to prevent the electrostatic generated by friction with the plate roller from adsorbing the measuring force of the bearing unit connected with the fixture, as well as the hair, dust and other foreign matters in the environment, causing printing quality problems. Flexible packaging enterprises should strengthen communication and understanding with ink production enterprises, so that ink production enterprises can fully understand their own printing equipment, including printing speed, printing substrate, drying method and ability, on-site environment, compound adhesive, end customer requirements, packaged products, etc., which is conducive to the preparation of appropriate ink. In addition, in order to realize the quality controllability and traceability of products, each batch of inks should be tested for ex factory and incoming quality, including viscosity, fineness, solid content, appearance and so on

source: China Packaging

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