Discussion on the selection of gravure ink from the perspective of procurement
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Raw material procurement is an important link for enterprises to achieve economic benefits. The quality and technical performance of raw materials are also the key links affecting product quality. In soft packaging printing raw materials, ink quality and technical performance are the most important factors affecting the quality of packaging materials. As a technical staff responsible for the procurement of raw materials in soft packaging enterprises, the author intends to select the gravure ink from the purchase, including its applicability, economy and peers to explore.
First, the supplier's choice
The choice of upstream supply companies is based on the internationally accepted ISO9001,The quality assurance system requires that the ink be tested first, and conclusions based on the opinions of the technology, production personnel and customers. If the requirements are met, the supplier and technicians will be invited and the customer representatives will be invited to conduct on-the-spot investigations on a number of ink manufacturers, including production site, product performance, R&D strength, and customer satisfaction. Because the printing suitability of ink is related to the ambient temperature and humidity, the choice of ink supply companies should also consider the climate gap, giving priority to companies with similar geographical proximity. According to the principle of “Quality First, Price Purchasing”, “Equivalent Quality vs. Price, Same Price Price Service”, at least two ink production enterprises are selected to be listed in “List of Raw Material Qualified Suppliers” to achieve fixed-point procurement. The inspection of qualified suppliers shall be conducted every two years, mainly for comprehensive evaluation of product quality, technical performance, price, delivery date, technical service and customer satisfaction. The jury consists of technology, production, supply, sales and customers. Representative and senior management. In particular, it pays attention to the technical service and communication capabilities of suppliers, and can actively participate in solving problems when printing quality problems occur, and can assume due responsibility. It is necessary to pay attention to the importance of ink quality in packaging and printing, and strengthen the management of ink production enterprises as first-class upstream customers to achieve "win-win development" in the value chain.
Second, the applicability of the ink
When purchasing inks, first consider the applicability of the ink. The applicability of the ink is based on the following aspects:
1. Printing substrate
Printing substrates of different resins should use inks of different resin systems. Currently commonly used printing substrates are BOPP film, BOPET film, BOPA film, PE.
Film and the like. According to the "similar compatibility" principle, only the base resin is similar or similar, and the printed substrate and the ink will have good adhesion. In the ink system, the binder resin plays a key role in adhesion. The gravure ink currently developed is divided into a benzene solvent type ink, an alcohol solvent type ink, a water solvent type ink, etc. according to a solvent. According to the binder resin, it is divided into chlorinated polypropylene ink, polyurethane ink, polyamide ink and the like. Among them, chlorinated polypropylene ink is suitable for
BOPP film printing; polyurethane ink is suitable for BOPET film, BOPA film printing, can be cooked at high temperature, boiled; 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 ability, plate roll performance, gravure printing (printing, printing), printing color, printing order, ambient temperature, humidity, and the like. The process conditions directly affect the transfer rate of the ink, the drying speed, etc., so the ink should be selected reasonably and economically according to the process conditions. For example, when the humidity at the production site is relatively high and the printing speed is high, high-grade inks with high transfer rate and fast drying speed should be selected to prevent the film from sticking after printing. Under the conditions of air drying and fast printing speed, the ink with high viscosity and antistatic agent is selected to avoid the quality problem caused by static electricity.
3. Printing effect
Printing effects include the hue, gloss, transparency, opacity, gradation, overprinting accuracy of the print. Different ink manufacturers have certain differences in hue, solid content, viscosity, gloss, and level of performance. Even the inks produced by the same manufacturer and different batches are not the same. Therefore, when doing the same product, after the sample submitted is obtained by the customer, the same batch of sufficient ink is purchased as much as possible to ensure consistency with the sample.
4. Post-press process conditions
After the plastic film is printed, it is also subjected to extrusion compounding, dry compounding, vacuum aluminum plating, slitting, bag making, etc., and even high temperature cooking, boiling, freezing, sterilization and the like are used in the customer's use. Therefore, the ink should be selected according to the post-printing process conditions and use conditions of the packaging material. For example, when performing dry compounding, it is necessary to consider the adaptability of the printing ink and the adhesive without affecting the peeling strength of the composited product. When processing such as bag making, high-temperature cooking, boiling, freezing, etc., it is necessary to consider the high and low temperature resistance of the surface printing ink, and to prevent the ink film from being detached and discolored.
5. Customer's conditions of use
The ink is an organic system composed of a plurality of chemical substances such as a pigment, an additive, a binder, a filler, and a solvent, and is attached to a plastic substrate by printing to form an ink film. 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' lives. Therefore, the selection of the ink must first consider the hygiene and safety of the ink, and it is odorless, and its resistance meets the customer's use conditions. The resistance of the ink includes light resistance, heat resistance, grease resistance, chemical corrosion resistance, and good compatibility with the packaged product. The printing ink should be resistant to friction, oxidation, water and light, and have certain antistatic properties. The additives added to meet the resistance of the ink are hygienic and non-toxic; the fillers that are not necessary to be added are not required.
Third, the economics of ink
The economics of ink include not only the purchase price, but also the quantity purchased. The purchase amount of ink should be calculated according to the material demand provided by the production department and the “raw material consumption quota” compiled by the technical department. When economic procurement is achieved as much as possible, the cost of use should be reduced according to the actual production situation. Because the ink, especially the coloring ink, is different from other raw materials, once it is left over, it is very difficult to use it again, and it has to be discarded, resulting in waste. Achieving close proximity to “zero inventory” not only reduces the capital occupation, but also selects the bias of the primary color ink according to the customer's requirements, ensuring that the color of the printed product is consistent. For example, the primary color red is more red and purple. The primary color blue is partial blue and purple. The primary color is divided into green and red. In the case where it is impossible to artificially control the temperature and humidity of the on-site environment, it is necessary to select inks containing different additives for different on-site environments, thereby reducing the increase in the use cost due to temporary addition during the printing process. The ink is required to have a certain antistatic property to prevent electrostatic adsorption of air generated by friction with the plate roller and foreign matter such as hair and dust in the environment, resulting in printing quality problems. Flexible packaging companies should strengthen communication and understanding with ink manufacturers, so that ink manufacturers can fully understand their printing equipment, including printing speed, printing substrate, drying methods and capabilities, on-site environment, composite adhesives, end customer requirements, and The packaged product, etc., facilitates the formulation of a suitable ink. In addition, in order to achieve product quality controllability and traceability, each batch of ink must be tested at the factory and in the factory, including viscosity, fineness, solid content, appearance and so on.