PVC is the six major general-purpose thermoplastics, general-purpose plastic features are: (1) better overall performance, wide range of applications; (2) easy molding, forming a wide range of applications; (3) low prices.
PVC is such an easy to shape; better overall performance; easily modified to meet the performance requirements of a wide range of low-cost, easy to buy a plastic on the market. In a sense, China started in 1958, the use of electrolytic synthesis of chlorine and calcium carbide synthesis of acetylene, and then the production of vinyl chloride monomer, a PVC resin after polymerization, processed into a PVC film by rolling method, packaging ammonium carbonate fertilizer is China’s first soft plastic packaging, plastic packaging is our initial product.
PVC is a kind of thermosensitive thermoplastics which is easily decomposed when heated. According to the different polymerization methods, there are four kinds of suspension PVC, emulsion PVC, bulk PVC and solvent PVC. Among them, over 85% are produced by suspension polymerization PVC resin powder, its performance is characterized by good overall performance, widely used in extrusion, calendering, injection molding and compression molding process, as China does not produce solvent method PVC (due to solvent toxicity, recovery equipment complex, high production costs) And bulk method PVC (polymerization reaction is too violent, can not control). Therefore, the currently marketed more than 85% of the suspension PVC and some emulsion method PVC, emulsion method PVC, the process is more complex, more expensive, post-treatment processes and more technical requirements, because the emulsion method PVC can be a paste, Widely used in paste resin impregnation, coating, dipped, sugar and other processing. Therefore, it should be noted that the paste resin should be noted that 100% of the suspended resin PVC is not a plasticizer and solvent paste, a small amount of resin particles suspended suspended PVC powder can be blended into the emulsion resin powder, plasticizer And solvents formulated into a paste-like material, this small particles of suspended PVC resin called blending resin.
Suspended resin due to the different suspensions used in aqueous media (for example: different polyvinyl alcohol and gelatin), the production of PVC resin powder compact and loose type of different, loose PVC plasticizer absorption speed, plasticization time Short, loose particles within the particle diameter of 50 ~ 150μm, while the close PVC is the opposite, the particle inside the compact diameter of 5 ~ 100μm, plasticizing and absorbing plasticizer slow.
The characteristics of PVC suspension resin are as follows: (1) PVC is a colorless, odorless and tasteless thermoplastic heat-sensitive amorphous polymer with an average molecular weight of 3.6 to 85,000. According to the average molecular weight from high to low, PVC can be divided into a type, Type II, Type III to Type VII; (2) PVC resin itself is non-toxic, but Vinyl Chloride Monomer is a strong toxic carcinogen, therefore, PVC resin is toxic, is that it contains The amount of monomer, the international community generally believe that the PVC resin VCM content of less than 1PPm for non-toxic PVC resin can be used for food and drug packaging; (3) PVC glass transition temperature (Tg) of 87 ° C, the melting temperature of 210 ℃, 100 ℃ under the heating began to decompose, the temperature> 130 ℃ decomposition quickly, in the event of melting temperature will be all broken out, therefore, PVC can not be processed in the absence of thermal stabilizers molding; (4) PVC Is a typical amorphous polymer, so PVC products can be a transparent material; (5) PVC flame retardant, self-extinguishing; (6) PVC in the unmodified case, the impact of the product is low; ( 7) PVC has good resistance to grease, chemical resistance (8) PVC excellent electrical insulation.
PVC film products formula points are: (1) PVC packaging products according to the requirements of a soft, semi-rigid and hard points, the general amount of plasticizer 10PHR (Per hundred Rosin, based on 100 parts by weight of the resin Other materials, parts by weight) or without plasticizer for the rigid PVC products; plasticizer dosage of 10 ~ 40PHR semi-hard products, plasticizers dosage of more than 40PHR for the soft PVC products; (2 ) PVC is a thermosensitive plastic, the formula must have a thermal stabilizer, the amount of general thermal stabilizer is 5 ~ 8PHR, too little, the thermal stability is insufficient, will produce decomposition, too much, then the PVC formula material melting temperature increases, Is not conducive to the flow of the melt; (3) In order to improve the melt flow of PVC processability, PVC formulations should be added processing aids, the most commonly used processing aids are ACR and CPE, ACR is an acrylic resin copolymer, and CPE is a chlorinated polyethylene with an added amount of 3 to 6 PHR (total); (4) Be careful of non-toxic and toxic formulations; non-toxic PVC formulations, including resins and all auxiliaries, should be non-toxic; ) PVC itself is good transparency, such as formula transparent material should be The amount of solid additives without the use of an opaque, while the use of liquid additives, such as: thermal stabilizers using a liquid or a liquid organotin stabilizer Ba-Cd-Zn composite stabilizer.
Post time: Nov-10-2017