Adhesives for pharmaceutical packaging
There are two main types of adhesives for pharmaceutical packaging, pressure-sensitive adhesives and polyurethane adhesives. 1. Pressure sensitive adhesive Suitable substrates for pressure sensitive adhesives include papers and plastic films, such as polyvinyl chloride, polyethylene, polypropylene, polyester, polytetrafluoroethylene, polyimide, cellulose acetate, etc. Metals such as aluminum foil, copper foil, lead foil, etc. The main components of pressure-sensitive adhesives include synthetic resin adhesives (including natural rubber synthetic rubbers, celluloses, polyacrylates), tackifiers (rosin, rosin esters, various petroleum resins, epoxy resins or phenolic resins), Plasticizers (chlorinated paraffins, phthalic acids), antioxidants, stabilizers, cross-linking agents, colorants and fillers. The pressure-sensitive adhesives used in early pharmaceutical packaging were all made of natural rubber. Their formulas were 100 parts of refined natural rubber, 75 parts of polypinene resin (melting point 70 ° C), 5 parts of petroleum resin, and partially polymerized trimethyl methacrylate. 2 parts of chlorodichloroquinoline. The other formula is made up of 100 parts of smoked rubber, 50 parts of zinc oxide, 75 parts of hydrogenated rosin, and a small amount of tackifier and plasticizer. Later, natural rubber was replaced by synthetic rubber and synthetic resin. Among them, acrylate and its copolymers were most commonly used. For example, acrylic acid copolymer emulsion high-strength pressure-sensitive adhesive, the ratio of the manufacturing method is to make 100 parts 43% solid content Butyl acrylate-2-ethylhexyl acrylate-vinyl acetate copolymer emulsion (composition ratio 50:17:33) and 30 parts of 50% solids content ethylene-vinyl acetate-vinyl chloride copolymer emulsion (composition ratio 19:36:45) mixed, coated on the polypropylene film treated with corona discharge, and dried at 110 ℃ for 1 minute to make a pressure-sensitive adhesive tape. The peel strength of this tape to stainless steel is 600 g / 25 mm. With the continuous improvement of the hygienic performance requirements for pharmaceutical packaging materials, the additives added with the adhesive of natural rubber have odors and some are toxic, and they have not been used in pharmaceutical and food composite packaging. However, acrylic pressure-sensitive adhesives still have certain advantages, such as being single-component, not cross-linking and curing, no need for glue, simple to use, and unused glue solution will not be bad overnight or longer, as long as It can be stored in airtight and airtight. Furthermore, the surface condition of the adherend is excellent. Many non-polar materials, such as plastics and metal materials, can adhere firmly even with small surface tension. However, due to the wide variety of materials in composite pharmaceutical packaging, companies have turned to two-component polyurethane adhesives for the compounding of polar plastic materials and non-polar materials. 2. Polyurethane adhesive Polyurethane adhesive has a high degree of elasticity. Compared with other flexible adhesives, it has better heat resistance, solvent resistance, cold resistance, chemical resistance, oxidation resistance and ozone resistance. It has good affinity for metals, plastics, wood, rubber, and fabrics, so it is widely used, especially in the fields of pharmaceuticals and food packaging. The most widely used are plastic-to-plastic composite, metal-to-plastic composite, and blister packaging hot pressing. The earliest application of polyurethane adhesives was in the 1960s, when food composite packaging was just released on the market. When it was used as an adhesive, it was mainly divided into polyisocyanate, urethane prepolymer, and isocyanate modified polymer according to its composition. class. ①Polyisocyanate Usually triphenylmethane P-triisocyanate, hexamethylene diisocyanate, diphenylmethane-4, 4-diisocyanate or toluene diisocyanate, etc. These polyisocyanates are used alone, mainly as crosslinking of rubber adhesives Agent, or as a curing agent for polyester and polyether polyhydroxy compounds. Polymers used with it also include polyacrylates, epoxy resins, xylene resins, polyphenolamine resins, etc. ②urethane prepolymer It is a partial reaction product of polyisocyanate and polyhydroxy compound. Because the end group of this polymer has NCO group, it can be cured in the presence of a suitable curing agent, or it can be cured by the moisture of the air to make a single group Parts of adhesive. ③Isocyanate modified polymer It is a linear polymer which reacts with diisocyanate and polyester or polyether with more than two functions, and has hydroxyl group at the end group, also known as thermoplastic polymer. According to the dosage form, polyurethane adhesives can be divided into two categories of single component and double component, the latter is better than the former in terms of adhesive strength. The two-component component A is mainly an isocyanate-modified polymer, and the component B is also the urethane prepolymer that has been introduced. The polyols are mainly castor oil or polyethylene glycol. The single component can be divided into two categories, one type uses the component A of the two components directly, that is, the modified polymer of isoleic acid ester; the other type is the carbamate produced by the reaction of diisocyanate and ethylene glycol Ester, which has good adhesion properties inherent in short-chain compounds such as ethylene glycol.  It is new latest design 1400W Hair Dryer. it comes with hot and cool function and also comes with hi and low function . so it have dual switch control. that is not comes with other.in today's day and age, it comes with good quality and low price. so all can afford it. From room occupying appliances and pocket-fitting devices, to meters and meters of cables, no home is stranger to any of these. 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