Application analysis of the hottest adhesive in fl

2022-08-05
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Application analysis of adhesive in flexible packaging (Part I)

Abstract: This paper comprehensively expounds the adhesive used in flexible packaging, mainly from two aspects: application technology and adhesive quality control. It has a certain guiding significance for flexible packaging enterprises, and hopes to exchange ideas on technology and make common progress

key words: adhesive, film, ink, composite process, quality control

Preface: with the rapid development of the flexible packaging industry today, the quality requirements are becoming higher and higher. Any enterprise pays more attention to the quality problem, which is also related to the survival and lifeline of the enterprise. This paper expounds and analyzes the application of adhesives in flexible packaging and quality control from different angles

I: various factors affecting composite quality

a - ink: ink is composed of pigments, binders, solvents and additives

(1) pigments: pigments are generally insoluble in water and binder, and most of them are suspended in solution; 3. In the ink, the maximum force FM shall not be less than 94.3-384kn; The pigment must have high tinting power, chemical stability and light resistance. It has good dispersibility in general ink connecting materials. The particles are required to be fine. After adding the ink, it must not affect the fluidity of the ink, and it must have good hiding power; The covering power is not strong, the leveling performance is poor, and the printed film has spots on the light. There are obvious spots after coating (especially the aluminized film), which is mostly caused by the hiding power of the pigment. Pigments generally account for about 8~35%, so they have a great impact on the quality of composite film products

(2) binder: because binder is used to connect film and ink. The poor bonding force of the connecting material will make the ink and the outer membrane not firmly bonded. After compounding, the ink will be completely transferred to the inner membrane. This phenomenon may also be caused by the poor corona treatment of the outer membrane. Connecting materials to a large extent determine the viscosity, viscosity, dryness and flow properties of the ink. This has a great impact on the composite adhesive. The connecting material is a liquid with a certain viscosity

(3) solvent: the ideal solvent should be polymer composites and 3D printing with good fast drying performance. If there are too many residual solvents, it will cause odor and surface quality problems of the composite film. Therefore, in the selection of solvents, the first thing to consider is the volatilization rate and the release between substrates

(4) additives: in order to improve the printing adaptability of ink, additives (plasticizer, adhesive remover, anti drying agent) are often added during manufacturing. Some additives will also affect the composite; For example, the anti drying agent is mainly composed of heavy oil and white kerosene to prevent anti adhesion after printing. Anti drying agent can quickly penetrate into the ink surface. Due to the characteristics of anti drying agent, it is a contradiction with the adhesion of laminating adhesive. So the amount of anti drying agent is very important. The manifestation of too many anti drying agents on the laminating film: after compounding, the place with ink is firm, with high peel strength, and the place without ink has poor fastness. After ripening, the place with ink is very firm, the peel strength is higher, and the place without ink has almost no fastness. In addition, as for metal substitutes, LANXESS reinforced nylon 66 is influenced by other additives, such as plasticizer, adhesive remover, antioxidant, etc

b -- influence of film on composite quality

(1): types and characteristics of film film

① films used for printing and laminating mainly include polyethylene (PE), polypropylene (PP), polyester (PET), nylon film (PA), aluminum foil (AL), etc

① polyethylene (PE): it is polymerized from ethylene produced by petroleum cracking. Due to different manufacturing and control, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and cross-linked high density polyethylene (CLPE) can be obtained. The characteristics are: "with the increase of density, the mechanical properties and barrier properties are improved, and the heat resistance is also good." The common composite structures are BOPP/PE, PET/VMPET/PE, PET/PE, PET/Al/NY/PE, etc

② polypropylene (PP): successfully developed nano material green metro ticket propylene resin is obtained by coordination polymerization of monomers. It can be divided into homopolymer polypropylene and copolymer polypropylene. It is characterized by higher heat resistance and transparency than polyethylene, but lower temperature resistance than polyethylene. There are generally CPP (casting type) and OPP (drawing type)

polyester (PET): with the higher and higher requirements for packaging, polyester (PET) packaging has been increasingly recognized by people, which is related to its characteristics. Pet is a plastic material with excellent performance, which is mainly characterized by high strength, the best strength, toughness, rigidity, wear resistance, creep resistance, temperature resistance, chemical resistance, etc. Common composite structures include PET/Al/NY/CPP, OPP/CPP, PET/VMPET/CPP, etc

nylon film (PA): nylon film is a film (OPA) or cast film (CPA) made of nylon-6 resin after biaxial stretching. It has very good barrier property and is transparent and beautiful. The mechanical properties are greatly affected by temperature and moisture. If nylon is hygroscopic, it will have a great impact on the peel strength of composite products. Nylon has excellent puncture resistance and is often used as a package for frozen food

aluminum foil (AL): aluminum foil is the only metal foil in flexible packaging materials. Aluminum foil is a metal material, and its water resistance, gas resistance, shading and taste retention are incomparable with any other material. Aluminum foil is made of 99.00%~99.97% electrolytic aluminum by multiple calendering. It has good stability at high or low temperature, and has been widely used in packaging, especially in drug packaging. Its disadvantage is that it has low strength, is easy to tear, and is not resistant to acid and alkali. Therefore, it can not be used alone. The unwinding tension should be as small as possible during compounding

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