Correct selection and use of gravure printing mate

2022-06-23
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Correct selection and use of gravure printing materials (Part 2)

4) liquid packaging

the so-called liquid packaging film is the packaging film whose content is liquid. According to the printing method, it can be divided into surface printing liquid packaging film and internal printing liquid packaging film

surface printed liquid packaging film generally adopts three-layer coextrusion or five layer coextrusion PE film (black-and-white film, milky white film, matte film, packaging machine 'target=u blank> transparent film), which is mainly used for liquid packaging of milk, soybean milk, soy sauce, vinegar, etc. and frozen packaging of frozen meat food. The liquid packaging film needs to undergo uniform corona treatment before printing. The third treatment surface: the critical surface tension of uniform thickness should reach 40 ~ 41 dyne. For common internal printing liquid packaging films such as milk film packaging, biaxially oriented polypropylene (BOPP), matting polypropylene (BOPP) and polyethylene terephthalate (PET) can be used as substrate, and high-strength metallocene polyethylene can be used as laminating substrate. For the three-layer composite, PET film can be used for printing, and aluminum foil or pet aluminized film can be used for the middle layer because of their good barrier performance, and then metallocene polyethylene with good heat sealing and high strength can be compounded. For liquid packaging such as cosmetics and pesticides, including impact blade and centering film for clamping sample anvil, pet is selected as printing surface material, aluminum foil or pet aluminized film is selected as intermediate layer, and metallocene polyethylene is used as the third layer. Common lamination combinations: PET film/pet aluminized film/metallocene polyethylene film or PET film/aluminum foil/metallocene polyethylene film. Pet has high mechanical strength, strong toughness and excellent dimensional stability, so it is often used as the surface layer of liquid packaging film. When printing pet substrate, it is required that the surface tension of the printing surface should reach more than 50 dyne, and the pet aluminized film in the middle layer of the composite film should be corona treated on both sides

5) steaming packaging

the so-called steaming packaging is a packaging in which the contents are packed and boiled in a 120 ℃ steam boiler for 40 minutes without any broken bags. The commonly used structures are pa/pe, pa/cpp and pet/al/cpp

polyamide (PA) is commonly known as nylon. Nylon film is OPA or CPA film made of nylon 6 resin after biaxial stretching. It has high strength, can maintain high modulus and stiffness in a wide temperature range, and has many advantages such as high oxygen barrier, puncture strength, tear strength, high temperature resistance and printability. Nylon film also has high transparency and safety. Based on these advantages, nylon film has been widely used in food packaging, pharmaceutical packaging and industrial packaging. For example, 12 μ PA of M and 30 ~ 80 μ M of CPP or PE, in which nylon has puncture resistance, high impact strength and high temperature stability, while other resins such as polyethylene and non stretched polypropylene have excellent heat sealing and barrier properties. The composite product has good cold storage, good corrosion resistance, puncture resistance, gas resistance and aroma preservation, and can be cooked at high temperature. The disadvantage is that it is easy to absorb moisture. After absorbing moisture, the barrier and strength will decrease, the adhesion of the ink will decrease, and the film will wrinkle. Therefore, it should be stored in a dry place and pay attention to the humidity change of the printing environment

in modern packaging, aluminum foil is used for many advanced composite materials that require no light transmission. Aluminum foil is made of electrolytic aluminum with a purity of more than 99.5% by calendering. Compared with paper, plastic film and other materials, aluminum foil has the advantages of good barrier property, strong air tightness, moisture resistance and waterproof, strong content protection, excellent thermal conductivity and shading. At the same time, it is non-toxic. It can be compounded with paper, plastic film and other materials to facilitate printing and coloring. Therefore, aluminum foil is a packaging material that cannot be replaced at present and has a wide range of uses. Aluminum foil used in composite materials, with a thickness of 7 ~ 9 μ m. In practical use, in addition to being used as chocolate and medicine packaging, the thickness should be selected according to different contents. There are four widths of aluminum foil produced in China, which are 10 ~ 39mm, 39 ~ 130mm, 130 ~ 220mm and 220 ~ 600mm respectively. There are 18 thicknesses, of which the thinnest is 5 μ m. The thickest is 200 μ m。 Aluminum foil should be pretreated before printing, that is, coated with a layer of shellac coating or nitrocellulose to improve the adhesion of ink

bopp/al/ldpe is used for barrier light proof or vacuum flexible packaging, in which BOPP is pretreated for internal printing, coated with polyurethane adhesive, and mixed with aluminum foil (thickness 10 ~ 30 μ m) After the first dry compounding, the color printing pattern is more shiny and eye-catching after being contrasted with silver white aluminum foil. Next, the adhesive is coated on the other side of the aluminum foil and then compounded with the polyethylene substrate (thickness 30 ~ 100 μ m) After curing, shaping, cutting, t-sealing, three side sealing, h-sealing and other bag making, or directly sent to the food, drug, cosmetics and other packaging lines for automatic high-speed continuous packaging. LDPE used for bonding with Al surface shall undergo surface activation treatment. In the above process, BOPP can be replaced by more crisp pet, while LDPE can be replaced by CPP. Example 12 μ Dry compounding method for pet of M and 7 ~ 14 μ M, and then 30 ~ 80 μ M CPP. The composite product has the characteristics of gas resistance, moisture resistance, fragrance preservation, high mechanical strength, cooking and low temperature refrigeration. It is mainly used for the packaging of baked food, meat products, cream, etc

the above introduces the selection of several common packaging materials. In actual production, we will encounter various types of packaging. In the selection of materials, we should not only consider the beauty of the packaging, but also consider the characteristics and packaging methods of the contents of the packaging. What kind of materials should be selected for what type of packaging. Do not "trade the cat for the Prince". If there is any mistake in the selection of materials, the loss after packaging will be incalculable. Therefore, printers are required to understand the characteristics and special requirements of the contents of the packaging before packaging, and then pay more attention to the selection of materials. For the development of new products, it is required to do a good job of testing before mass production. Remember, only when everything is ready can we make high-quality products with flexible packaging. Author shipeiqin Shandong Linyi Xingda company color printing factory source: the printing world copyright belongs to the original author. This article is for everyone to share and learn. If the author believes that this is due to infringement when working on the gear pump, please contact us. We will delete it immediately after verification

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