one. Definition of resin Resin usually refers to the softening or melting range after being heated. When softened, the resin tends to flow under the action of external force, and is a solid, semi-solid, and sometimes liquid organic polymer at normal temperature. Broadly speaking, any polymer that can be used as raw material for plastic products is called resin. Resin has a natural resin and synthetic resin points. Natural resin refers to the nature of animal and plant secretions derived from amorphous organic substances, such as rosin, amber, shellac and so on. Synthetic resin refers to a resin product obtained by chemical synthesis of simple organic compounds or by chemical reaction of some natural products. two. The definition of plastic Plastics refers to the resin (or monomer in the process of direct polymerization) as the main ingredient to plasticizers, fillers, lubricants, colorants and other additives as an auxiliary component in the process of flow molding s material. Plastic mainly has the following characteristics: ①most of the plastic light, chemical stability, will not rust; ② impact resistance is good; ③ has good transparency and abrasion resistance; ④ insulation, low thermal conductivity; ⑤ general moldability, good coloring, low processing costs; ⑥ most of the plastic poor heat resistance, thermal expansion, easy to burn; ⑦ dimensional stability is poor, easy to deformation; ⑧ majority of plastic low temperature resistance, brittle at low temperatures; ⑨ easy Aging; ⑩ Some plastics are easily soluble in solvents. Resin and plastic classification one. Classification of resins There are many ways to classify resins, which can be classified into natural resins and synthetic resins by the source of the resins. They can also be classified according to the synthesis reaction and the main chain composition. 1. According to the resin synthesis reaction classification According to this method, the resin can be divided into addition polymer and polycondensate. Addition polymer refers to the polymer obtained by addition polymerization, the chemical structure of the chain link structure and monomer the same formula, such as polyethylene, polystyrene, polytetrafluoroethylene and so on. Condensed polymer refers to the polymer prepared by condensation polymerization, the structural unit of the chemical formula and the monomer formula, such as phenolic resin, polyester resin, polyamide resin. 2. According to the molecular composition of the main chain of the resin molecules by this method can be divided into carbon chain polymer chains, hybrid polymers and organic polymers. Carbon chain polymer means a polymer whose main chain is composed entirely of carbon atoms, such as polyethylene, polystyrene and the like. Heteropoly chain polymer refers to the main chain from the carbon and oxygen, nitrogen, sulfur and other elements composed of two or more polymers, such as polyacetal, polyamide, polysulfone, polyether and so on. Elemental organic polymer refers to the main chain does not necessarily contain carbon atoms, mainly by the silicon, oxygen, aluminum, titanium, boron, sulfur, phosphorus and other elements atoms, such as silicone. two. Plastic classification Plastic classification system is more complex, a variety of classification methods also cross, according to conventional classification are the following three: First, according to the classification of the use of characteristics; second is classified according to physical and chemical properties; third is classified according to processing methods. 1. According to the use of property classification According to different types of plastic use characteristics, usually divided into general-purpose plastic, plastic and special plastic three types of plastics. ⑴ general plastic generally refers to the large output, wide use, good moldability, cheap plastic, such as polyethylene, polypropylene, phenolic and so on. ⑵ plastic general engineering plastics can withstand the role of a certain force, with good mechanical properties and high temperature, low temperature performance, better dimensional stability, can be used as engineering plastics, such as polyamides, polysulfone. In engineering plastics they are divided into general engineering plastics and specialty engineering plastics two broad categories. General engineering plastics include: polyamide, polyacetal, polycarbonate, modified polyphenylene ether, thermoplastic polyester, ultra-high molecular weight polyethylene, methyl pentene polymer, vinyl alcohol copolymer. Special engineering plastics have cross-linked non-cross-linked type of points. Cross-linked are: poly amino bismaleimide, poly triazine, cross-linked polyimide, heat-resistant epoxy refers to such means. Non-crosslinked types include: polysulfone, polyethersulfone, polyphenylene sulfide, polyimide, polyetheretherketone (PEEK) and the like. ⑶ special plastic generally refers to a special function, can be used for aviation, aerospace and other special applications of plastic. Such as fluoroplastic and silicone with outstanding high temperature, self-lubricating and other special functions, and enhance the plastic and foam with high strength, high cushioning and other special properties, these plastics are all belong to the category of specialty plastics. ①enhanced plastic. Reinforced plastic raw materials in the shape can be divided into granular (such as calcium plastic reinforced plastic), fibrous (such as glass fiber or glass cloth reinforced plastic), flake (such as mica reinforced plastic) three. According to the material can be divided into Buki reinforced plastic (such as rag enhanced or asbestos-reinforced plastic), inorganic mineral filled plastic (such as quartz or mica filled plastic), fiber-reinforced plastic (such as carbon fiber reinforced plastic) three. ② foam. Foam can be divided into hard, semi-rigid and soft foam three. Rigid foam is not flexible, compression hardness is great, only to reach a certain value of stress before deformation, stress relief can not be restored to its original state; soft foam rich in flexibility, compression hardness is very small, it is easy to deform, after the stress relief Restoration of the original shape, the residual deformation is small; semi-rigid foam flexibility and other properties between the rigid between his soft foam. 2. Physical and chemical properties according to the classification of different physical and chemical properties of plastics, plastic can be divided into thermosetting plastic and thermoplastic plastic two types. ⑴ thermosetting plastic Thermosetting plastic is under heat or other conditions can be cured or insoluble (melt) characteristics of plastics, such as phenolic plastics, epoxy plastics. Thermosetting plastic is divided into two types of cross-linked formaldehyde and other types. Formaldehyde cross-linked plastics, including phenolic plastics, aminoplasts (such as urea - formaldehyde - melamine - formaldehyde, etc.). Other cross-linking plastics include unsaturated polyesters, epoxies, o-diallyl phthalate resins and the like. ⑵ thermoplastic plastic Thermoplastic plastic refers to the specific temperature range can be repeatedly heated softening and cooling hardened plastics, such as polyethylene, polytetrafluoroethylene and so on. Thermoplastic Plastics are divided into hydrocarbons, polar genes containing vinyl, engineering, cellulose and other types. ①hydrocarbon plastic. Is a non-polar plastic, with crystalline and non-crystalline points, crystalline hydrocarbon plastics, including polyethylene, polypropylene, etc., non-crystalline hydrocarbon plastics, including polystyrene and so on. ② containing polar genes of vinyl plastic. In addition to fluorine plastic, the majority of non-crystalline transparent body, including polyvinyl chloride, polytetrafluoroethylene, polyvinyl acetate and so on. The majority of vinyl monomers can be used free-radical catalyst for polymerization. ③ thermoplastic engineering plastics. Mainly include polyacetal, polyamide, polycarbonate, ABS, polyphenylene oxide, polyethylene terephthalate, polysulfone, polyethersulfone, polyimide, polyphenylene sulfide and so on. Teflon. Modified polypropylene, etc. are also included in this range. ④ thermoplastic cellulose plastics. Mainly include cellulose acetate, cellulose acetate butyrate, cellar, cellophane and so on. 3. According to the processing method According to various plastic molding methods, can be divided into film pressure, lamination, injection, extrusion, blow molding, casting plastic and reaction injection of various types of plastics. Plastic film pressure plastic material processing properties and general solid plastic similar plastic; Laminated plastic refers to the resin-impregnated fiber fabric, laminated, hot and combined into a whole material; injection, extrusion and blowing Plastic is mostly physical and processing properties similar to the general thermoplastic plastic; Casting plastic refers to the pressure can be little or under pressure, poured into the mold can be hardened into a certain shape of the liquid resin mixture, such as MC Nylon, etc .; reaction injection of plastic is the use of liquid raw materials, pressurized into the cavity, the reaction curing of certain shapes of plastic products, such as polyurethane.
