What are the methods by which plastics are made
The molding process of plastics refers to the process by which polymers made by synthetic resin manufacturers are made into final plastic products. Processing methods (often referred to as primary processing of plastics) include compression molding (molding), extrusion molding (extrusion molding), injection molding (injection molding), blow molding (blow molding), and calendering.
Compression molding
Compression molding, also known as molding or compression molding, compression molding is mainly used for phenolic resins, urea-formaldehyde resins, unsaturated polyester resins and other thermosetting plastics molding.
Extrusion
Extrusion, also known as extrusion molding, is the use of extrusion machine (extruder) will be heated resin continuously through the mold, extrusion of the desired shape of the product method. Extrusion is sometimes used for thermosetting plastics and can be used for foam molding. The advantage of extrusion is that various shapes of products can be extruded, high production efficiency, automation, continuous production; disadvantage is that thermosetting plastics can not be widely used in this method of processing, product size is prone to deviation.
Injection molding
Injection molding is also known as injection molding. Injection molding is the use of injection molding machine (or injection machine) will be thermoplastic melt under high pressure into the mold by cooling, curing to obtain the product method. Injection molding can also be used for thermosetting plastics and foam molding. The advantages of injection molding are fast production speed, high efficiency, operation can be automated, can mold complex shaped parts, especially suitable for mass production. Disadvantages are high cost of equipment and molds, injection molding machine cleaning is more difficult.
Blow molding
Blow molding is also known as hollow blow molding or hollow molding. Blow molding is with the help of compressed air pressure to make the closed in the mold of the hot resin billet blowing for a hollow product method, blow molding, including blow molding film and blow molding hollow products two methods. Blow molding method can produce film products, a variety of bottles, barrels, pots and containers and children's toys.
Calendering
Calendering is the resin and a variety of additives by the expected treatment (kneading, filtration, etc.) through the calender of two or more calendering rollers turning the opposite direction of the gap processed into a film or sheet, and then peeled off from the calender rollers, and then cooled by a molding method. Calendering is a molding method mainly used for polyvinyl chloride resins, which can manufacture films, sheets, plates, artificial leather, floor tiles and other products.
Classification, composition and properties of plastics
Plastic is a synthetic polymer material with a wide range of uses, and plastic products abound in our daily lives. From the toiletries we use when we get up, the tableware we use at breakfast, to the stationery we use when we work and study, the seat cushions and mattresses we use when we rest, as well as the shells of televisions, washing machines, computers, and the various shapes of lamps and lanterns that give us light at night ......
Plastics have gradually replaced many Has been used for decades and centuries of materials and utensils, become an indispensable assistant in people's lives. Plastic set of metal hardness, lightweight wood, glass transparency, ceramic corrosion resistance, rubber elasticity and toughness in one, so in addition to daily necessities, plastic is more widely used in aerospace, medical equipment, petrochemicals, machinery manufacturing, national defense, construction and other industries.
One, the classification of plastics
There are many types of plastics, so far the world into the production of plastics about three hundred kinds. Plastic classification methods, commonly used in two ways:
1, according to the nature of the plastic heat is divided into thermoplastic and thermosetting plastics
Thermoplastic molecular structure is a linear structure, when heated, softening or melting, can be molded into a certain shape, and then harden after cooling. In the heat to a certain extent and re-soften, after cooling and harden, this process can be repeated many times. Such as polyvinyl chloride, polyethylene, polystyrene and so on. Thermoplastic molding process is relatively simple, can be continuous production, and has a fairly high mechanical strength, so the development is very fast.
Thermoset plastics molecular structure is the body structure, in the heat also occurs when the softening, can be molded into a certain shape, but heat to a certain extent or add a small amount of curing agent, the hardening of the stereotypes, and then will not soften the heat and change the shape. Thermosetting plastics processed after molding, heat is no longer softened, and therefore can not be recycled, such as phenolic plastics, aminoplastics, epoxy resins and so on belong to this type of plastic. Thermosetting plastic molding process is more complex, so continuous production has some difficulties, but its heat resistance is good, not easy to deformation, and the price is relatively inexpensive.
2, according to the different uses of plastics are divided into general-purpose plastics and engineering plastics
General-purpose plastics refers to the production of large, low-priced plastics with a wide range of applications, including polyolefins, polyvinyl chloride, polystyrene, phenolic plastics and aminated plastics five varieties. Many products used in people's daily life are made of these general-purpose plastics.
Engineering plastics are plastics that can be used as engineering structural materials and replace metal to make machine parts. For example, polyamide, polycarbonate, polyformaldehyde, ABS resin, PTFE, polyester, polysulfone, polyimide and so on. Engineering plastics with low density, high chemical stability, good mechanical properties, superior electrical insulation, easy processing and molding characteristics, widely used in automotive, electrical appliances, chemical, mechanical, instrumentation, instrumentation and other industries, but also in cosmic navigation, rockets, missiles and other aspects.
Second, the composition of plastic
We usually use plastic is not a pure substance, it is formulated by many materials. One of the polymer (or synthetic resin) is the main component of plastic, in addition, in order to improve the performance of plastic, but also in the polymer to add a variety of auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, coloring agents, etc., in order to become a good performance of plastic.
1, synthetic resins
Synthetic resins are the most important component of plastics, its content in plastics is generally 40% to 100%. Because of the large content, and the nature of the resin often determines the nature of the plastic, so people often see the resin as a synonym for plastic. For example, polyvinyl chloride resin and polyvinyl chloride plastics, phenolic resins and phenolic plastics mixed together. In fact, resin and plastic are two different concepts. Resin is a raw unprocessed polymer, it is not only used in the manufacture of plastics, but also coatings, adhesives and synthetic fibers raw materials. In addition to a very small number of plastics containing 100% resin, the vast majority of plastics, in addition to the main component of resin, but also need to add other substances.
2, filler
Filler, also known as filler, it can improve the strength and heat resistance of plastic, and reduce costs. For example, phenolic resin can greatly reduce the cost of adding wood flour, so that phenolic plastics become one of the cheapest plastics, but also significantly improve mechanical strength. Fillers can be divided into two categories of organic fillers and inorganic fillers, the former such as wood flour, rags, paper and a variety of fabric fibers, etc., the latter, such as glass fibers, diatomaceous earth, asbestos, carbon black, etc..
3, plasticizers
Plasticizers can increase the plasticity and flexibility of plastics, reduce the brittleness of plastics easy to process molding. Plasticizers are generally miscible with the resin, non-toxic, odorless, light, heat-stable high-boiling organic compounds, the most commonly used is phthalate esters. For example, the production of polyvinyl chloride plastic, if you add more plasticizers can be obtained soft polyvinyl chloride plastic, if you do not add or add less plasticizers (dosage < 10%), the hard polyvinyl chloride plastic.
4, stabilizers
In order to prevent synthetic resins in the processing and use of the process of light and heat decomposition and destruction, to extend the service life, to add stabilizers in plastics. Commonly used stearate, epoxy resin and so on.
5, colorants
Colorants can make plastics have a variety of bright, beautiful colors. Commonly used organic dyes and inorganic pigments as colorants.
6, lubricants
The role of the lubricant is to prevent the plastic in the molding does not stick to the metal mold, at the same time can make the surface of the plastic smooth and beautiful. Commonly used lubricants are stearic acid and its calcium and magnesium salts.
In addition to the above additives, plastics can also be added to the flame retardant, foaming agent, antistatic agent, etc., to meet the different requirements of use.
Three, the characteristics of plastic
1, plastic has plasticity
As the name suggests, plastic is a material that can be molded. The so-called plasticity of plastic is a solid plastic can be softened by heating methods, and then the softened plastic in the mold, so that it is cooled and re-solidified into a certain shape of the solid. This property of plastic also has certain defects, that is, easy to soften and deform when exposed to heat, and some plastics will be deformed even with higher temperature water, so plastic products should not be in contact with boiling water in general.
2, plastic with elasticity
Some plastics are also like synthetic fibers, with a certain degree of elasticity. When it is stretched by external forces, the curled molecules are straightened by the flexibility, but once the tension is canceled, it will return to the original curled state, which makes the plastic with elasticity, such as polyethylene and polyvinyl chloride film products. But some plastics are not elastic.
3, plastic has high strength
Plastic is not as hard as metal, but compared with glass, ceramics, wood, etc., or has a relatively high strength and wear resistance. Plastic can be made into strong gears and bearings on the machine.
4, plastic has corrosion resistance
Plastic is not like metal in the moist air will rust, not like wood in the wet environment will rot or be microbial erosion, in addition to plastic corrosion resistant to acids and alkalis. Therefore, plastics are often used as water and liquid pipelines in chemical plants, doors and windows in buildings, and so on.
5, plastic has insulating
Plastic molecular chain is atoms to *** valence bonding combined, the molecules can not be ionized, but also in the structure of the transfer of electrons, so the plastic has insulating properties. Plastics can be used to make wrappings for electrical wires, electrical sockets, and housings for electrical appliances.
Attachment: Commonly used types of plastics are:
①Polyvinyl Chloride (PVC)
It is one of the most used plastics in construction. Rigid polyvinyl chloride density of 1.38 ~ 1.43g/cm3, high mechanical strength, good chemical stability, the use of temperature range is generally between -15 ~ +55 ℃, suitable for the manufacture of plastic windows and doors, downpipes, trunking and so on.
② polyethylene (PE)
Polyethylene plastic in the building is mainly used for water supply and drainage pipes, sanitary ware.
③ Polypropylene (PP)
Polypropylene density in all plastics is the smallest, about 0.90 or so. Polypropylene is commonly used to produce pipes, sanitary ware and other building products.
④Polystyrene (PS)
Polystyrene is a colorless and transparent glass-like plastic. Polystyrene is mainly used in construction to produce foam insulation materials, translucent materials and other products.
5 ABS plastic
ABS plastic is a modified polystyrene plastic, based on acrylene eye (A), butadiene (B) and styrene (S) for the composition of the three components.ABS plastic can be made of embossed plastic decorative panels, etc.
ABS plastic is a colorless, transparent glass-like plastic.
English:
Plastic had that several methods to make them
Plastic molding process is to point to by synthetic resin factory manufacture Plastic molding process is to point to by synthetic resin factory manufacture polymer made final plastic products process. Processing methods (often called plastic one processing) including compression (molding), extruded ( extrusion molding), plastic injection molding, blow molding () (), calender blow moulding machines etc.
compression
Also called molding or compression pressure molding, compression is mainly used for phenolic resin, urea-formaldehyde resin, unsaturated polyester resins
Extruded
Extruded say again extrusion molding, is to use crowded color-printed (extruder) will be heated resin continued through mold, extrusion shape of the products of the method. Extruded sometimes have to thermosetting plastic molding, and can be Extruded sometimes have to thermosetting plastic molding, and can be used for foam plastic molding. Extruded of advantage can squeeze various shapes of products, the production efficiency is high, can automatic and continuous production. Extruded of advantage can squeeze various shapes of products, the production efficiency is high, can automatic and continuous production. Defect is widely adopted this method cannot thermosetting plastic processing, goods size easily produce deviation. injection
Plastic injection molding, say again. Injection is the use of injection molding machine (or weigh injection machine) will Injection is the use of injection molding machine (or weigh injection machine) will thermoplastics melt under high pressure injection mould nei cooling, curing obtain product method. Injection can also be used to thermosets and foamed plastic molding. Injection is the advantage of producing speed, high efficiency, operation can be automation, can molding complex shape of parts, especially suitable for mass production. Injection is the advantage of producing speed, high efficiency, operation can be automation, can molding complex shape of parts, especially suitable for mass production. Defect is equipment and mold cost is high, the machine cleaning more difficult, etc.
Blow molding
Chuisu say again or hollow blow molding shape. Chuisu is made by the pressure of compressed air in the heat of the closed mold colophony billet blow bulge for a method of hollow products including, blow molding, blow mounding blown film hollow products in two ways. With blow molding method can produce film products, various kinds of bottle, barrel and other products. products, various kinds of bottle, barrel, pot of containers and children's toys, etc.
Calender
Calender is resin close by various additives expected disposal (kneading, filtration, etc.) through the calender of two or more in favor of the opposing calender roll gap processed into thin film or sheet, then from the calender roll cylinder on stripping down, then after finalizes the design of a kind of the shaping method. Calender is Calender is mainly used for polyvinyl chloride resin molding method, can make films, sheet, plank, artificial leather, such as floor brick products. Plastic the classification, composition and characteristics
Plastic is a versatile synthetic polymer materials, in our daily life plastic products can be found everywhere. Plastic is a versatile synthetic polymer materials, in our daily life plastic products can be found everywhere. We wake up from the use of the things that wash gargle, the breakfast tableware, to work and study with a stationery, when resting in the seat cushion, mattresses, and television sets, washing machines, computer shell, and night gave us light all sorts of modelling of lamps and lanterns...
Plastic with its superior performance gradually the place of many have been used for decades, hundreds of years of materials and the vessels, become people ingapore life's assistant. Plastic set metal hard sex, wood, portability, glass, ceramics, the transparency of the corrosion resistance , rubber flexibility and tenacity at a
A, plastic classification
Plastic is a lot of more phallic than other materials. Plastic is a lot of more phyletic, so far the world put into production of plastic has about 300 kinds. Plastic classification method is more, commonly used To have two kinds:
1, according to the nature of plastic after heated divided into thermoplastic and thermosetting plastic
Thermoplastic molecular structure are linear. Thermoplastic molecular structure are linear structure, the heated occurs when soften or melts, can SuZhi into certain shape, after cooling and harden. In heated to a certain degree of again bate, after cooling and harden, the process can be repeated several times. Such as PVC, PE, polystyrene, etc. Thermoplastic moulding process simpler. Thermoplastic molding process simpler, can continuous production, and with high mechanical strength, so fast development.
The molecular structure of thermosetting plastic shape structure is in when heated also happens bate, can SuZhi into certain shape, but heated to a certain extent or add a little curing agent, after hardened to finalize the design, then heat does not become soft change in shape. Thermosetting plastic processing & forming, heated no longer softening, can be used in the shape of the plastic. forming, heated no longer softening and therefore can not be recycled, such as bakelite, amino plastics, epoxy resin belong to this kind of plastic. Thermosetting plastic molding process is more complex, so continuous production has the certain difficulty, but its heat-resistant good, not easy
2, according to the different is divided into general use plastic plastics and engineering plastics
General plastic refers to large output, low cost and high quality plastic. General plastic refers to large output, low price and wide application range of plastics, mainly including polyolefin, PVC, polystyrene, bakelite and amino plastics five varieties. People's Daily life of many products are used by these common plastic.
Engineering plastic can be as a engineering Construction materials and replace metal manufacturing machinery parts and other plastic. Such as polyamide, polycarbonate, poly formaldehyde, ABS Such as polyamide, polycarbonate, poly formaldehyde, ABS, resin, ptfe, polyester, poly (PSF, polyimide, etc.) Engineering plastics possesses the density is small, the chemical stability, high mechanical performance good, electrical insulation is superior, processing &forming easily and other characteristics, widely used in automotive, electrical, chemical, machinery, instrument and Plastic components
We usually use plastic is not a pure substance, it is by the many materials preparation and become. One polymer (or called synthetic resin) is the main component of plastic, in addition, in order to improve plastics performance, but also add various auxiliary in polymer One polymer (or called synthetic resin is the main component of plastic, in addition, in order to improve plastics performance, but also add various auxiliary in polymer materials, such as packing, plasticizer, lubricants, stabilizer and colorants, etc, can become the good performance of plastics.
1, synthetic
1, synthetic resin
Synthetic resin is the most main components, plastic in the plastic the content is in commonly 40% ~ 100%. Due to the content, and properties of the resin is often decided by the plastic properties, so people often think of resin as plastic synonyms. For example For example the polyvinyl chloride resins and PVC plastic, phenolic resin and bakelite confuse STH with STH else. Actually resin with plastic are two different concepts. Resin is a kind of unprocessed raw polymer, it not only used in the manufacture of plastic, and still coating, adhesive and synthetic fiber materials. And plastic