Polyformaldehyde is known as polyoxymethylene (POM).
Polyoxymethylene is a no no side chain, high density, high crystallinity linear polymer, has excellent comprehensive performance.
Polyformaldehyde is a hard, dense material with a smooth, glossy surface, yellowish or white in color, and can be used for long periods of time at temperatures ranging from -40 to 100°C. It is resistant to abrasion and self-lubricating. Its abrasion resistance and self-lubrication is also superior to most engineering plastics, and has good resistance to oil, peroxide resistance. It is not resistant to acid, strong alkali and moonlight ultraviolet radiation.
Polyformaldehyde tensile strength of 70MPa, small water absorption, dimensional stability, glossy, these properties are better than nylon, polyformaldehyde is highly crystalline resin, thermoplastic resins in the toughest. With thermal strength, bending strength, fatigue strength are high, wear resistance and excellent electrical properties.
Polyformaldehyde properties:
Performance values
Specific gravity 1.43
Melting point 175°C
Extensile strength (yield) 70MPa
Elongation (yield) 15 percent
(Break) 15 percent
Impact strength (without notch) 108KJ/m2
(with notch) 7.6KJ/m2
Synthesis of homopolymerized formaldehyde is generally polymerized by condensation of an aqueous solution of formaldehyde in the presence of acid. The a-polyformaldehyde with a degree of polymerization of 100 or more is obtained, which is then heated to decompose into formaldehyde gas, and after refining and dehydration, the monomers are usually purified using partial pre-polymerization, and then passed into a dry solvent containing a small amount of initiator for polymerization. The molecular weight is significantly reduced by the presence of water. The initiator can be a Lewis acid or base, for example. But most of them use tertiary amine for anionic addition polymerization, the reaction is as follows: the end group of paraformaldehyde is half acetal (-CH2OH), when the temperature is higher than 100 ℃, the end group is prone to fracture, generally need to be stabilized by the end group treatment. Stabilization treatment can be heat-resistant to 230 ℃. Paraformaldehyde can be processed at a temperature of 170 to 200 ℃, such as injection, extrusion, blow molding and so on. It is mainly used as engineering plastics for automobiles, mechanical parts, etc. www.seafar.cn .
Typical applications of POM polyformaldehyde:
POM has a very low coefficient of friction and good geometric stability, especially suitable for making gears and bearings. It is also used in piping devices (piping valves, pump housings), lawn equipment, etc., as it is also resistant to high temperatures.
Injection Molding Process Conditions:
Drying Treatment: If the material is stored in a dry environment, drying treatment is usually not required.
Melting temperature: 190~230℃ for homopolymer materials; 190~210℃ for *** polymer materials.
Mold temperature: 80~105℃. In order to reduce the shrinkage rate after molding can choose a higher mold temperature.
Injection pressure: 700~1200 bar
Injection speed: medium or high injection speed.
Runner and gate: any type of gate can be used. If a tunnel gate is used, a shorter type is preferred. For homopolymer materials it is recommended to use hot nozzle runners. For *** polymer materials both internal and external hot runners can be used.
Chemical and Physical Properties of POM Polyformaldehyde:
POM is a tough, elastic material with good creep resistance, geometric stability, and impact resistance even at low temperatures.POM is available in both homopolymer and ****opolymer materials. Homopolymer materials have good ductile strength, fatigue strength, but not easy to process. *** polymer materials have good thermal stability, chemical stability and easy to process. Both homopolymer and *** polymer materials are crystalline and do not readily absorb moisture. the high degree of crystallinity of POM results in a fairly high shrinkage rate, which can be as high as 2% to 3.5%. There are different shrinkage rates for different reinforced materials.
Polyoxymethylene (pom) is a good performance of engineering plastics, in foreign countries have "take the steel", "super steel," said. pom has a similar metal hardness, strength and steel, in a wide range of temperatures and humidity have a very good self-lubrication, good fatigue resistance. pom has similar hardness, strength and steeliness of metal, has good self-lubrication, good fatigue resistance, and rich in elasticity in a wide range of temperature and humidity, in addition, it also has good resistance to chemicals. pom is lower than the cost of many other engineering plastics, is replacing some of the traditionally occupied by the metal of the market, such as the replacement of zinc, brass, aluminum and steel to make a lot of parts, since the introduction of the pom has been widely used in the field of electronics and electrics, machinery, instrumentation, daily light industry, automotive, building materials, agriculture and other fields. Since its introduction, pom has been widely used in electrical and electronic, machinery, instrumentation, daily light industry, automobile, building materials, agriculture and other fields. In many new areas of application, such as medical technology, sports equipment, etc., pom also showed good growth trend.
Application consumption continues to grow
pom used in those of the lubricity, wear resistance, rigidity and dimensional stability requirements are more stringent requirements of sliding and rolling mechanical parts, performance is particularly superior, and is therefore mainly used in industrial machinery, automotive, electrical and electronic, pipe fittings, and irrigation supplies and so on. In recent years, China's pom market is growing rapidly, in 2002 China's pom market apparent consumption of 13.657 million tons, 1990 to 2002 pom market apparent average annual growth rate of 11.7%. China's pom market is expected to 2005 apparent consumption of 16.8 million tons, 2000 to 2005 pom market apparent average annual growth rate will reach 10.3%. To 2010, China's pom market apparent consumption will increase to 19.7 million tons, 2005 to 2010 pom market apparent average annual growth rate will reach 3.2%.
Supporting the rapid development of China's pom market, the main factors are: the overall development of the national economy so that one of the five engineering plastics pom application market continues to expand, the amount of increasing; China's pom production raw materials are cheap and easy to get, pom production and trade in the lucrative; pom applications continue to appear in the field of new breakthroughs such as the research and development of modified materials, etc.. In view of the steady growth of China's market demand, the recent pom prices will continue to maintain a steady upward trend.
Technology gap should not be ignored
Although China's pom market demand continues to rise, but due to China's research and development of pom relatively late, the domestic pom production scale, output and varieties, quality has never been able to meet market demand. China's pom production and foreign advanced level, there are still high raw material consumption, small device size, unstable quality, less varieties of grades and other issues. For example, DuPont homopolymerization process pom formaldehyde (37%) tons of unit consumption of 2.56 tons, there are reports of 3.08 tons, while the domestic production of pom formaldehyde tons of unit consumption of 5 to 6 tons, although the improvement has been reduced, but the gap is still large.
China's pom industry for many years production capacity and production are lower, production capacity and production still can not meet market demand. 2002 China's pom manufacturers only 3, of which only the yuntianhua group company's pom production unit for 10,000 tons (now expanding for 20,000 tons / year). 2002 China's pom production capacity of 1.28 million tons / year, the output of about 10,000 tons. For 10,000 tons. 1966 to 2002, China's pom production capacity average annual growth rate of 16.7%, the average annual growth rate of production of 18.8%, it can be seen that the expansion of domestic pom production capacity of manufacturers is imperative. It is expected that in 2005 China's pom manufacturers will reach 6, the total production capacity will be up to 130,000 tons / year; is expected in 2010 China's pom production capacity of 190,000 tons / year, 2005 to 2010 pom production capacity will reach an average annual growth rate of 7.9%.
Caused by China's pom production capacity growth can not meet market demand is: the domestic pom market is growing faster, and China's pom production base is relatively weak; in addition, pom is a capital- and technology-intensive materials chemical products, China's huge market has attracted the attention of foreign companies, foreign companies have been wanting to occupy the market in our country, unwilling to transfer technology, so that the domestic pom technology level is slow to improve. pom's technical level is slow to improve, can not meet user needs; and then there is a long time, China's economic system and business mechanism does not comply with the laws of the market economy, the enterprise can not get enough capital investment in a timely manner, restricting the development of pom production.
Import-export imbalance
China's pom production has increased, but still can not meet the needs of the domestic market, every year to import a large number of pom. China's imports of pom of the main countries and regions are Japan, the United States, South Korea, and China's Taiwan Province of China, etc. In 2002, China's pom imports of 135,570,000 tons, 1995 to 2002 years. Pom imports average annual growth rate of 26.3%. China also has a small amount of pom export trade each year, in 2002, pom exports 0.9 million tons.
China's high-tech industries and the development of new industries, so that the demand for engineering plastics increased significantly. pom as a variety of industries are very suitable for a variety of engineering plastics, development prospects. It is understood that there are now a number of domestic pom in progress in the project, such as DuPont - Asahi Kasei (Zhangjiagang) company's pom project has broken ground, Shanghai Blue Star Chemical New Materials Factory pom proposed project is actively operating. According to China's pom proposed project, in the raw material base and technical base of the location, the introduction of capital and advanced technology and equipment, the construction of an economic scale of the pom device, will be the trend of China's pom industry development.
POM performance parameters:
Density
g /cm3
1.39
Water absorption
percent
0.2
Continuous use of the temperature
℃
-50--110
Yield tensile strength
MPa
63
Yield tensile strain
%
10
Ultimate tensile strength
MPa
Ultimate tensile strain
%
31
Impact toughness
Kj/㎡
Notched impact toughness
Kj/m2
6
Rockwell hardness
MPa
135
Shore hardness
MPa
85
Flexural strength
MPa
Modulus of elasticity
< p>MPa2600
Softening Temperature
°C
150
Heat Deflection Temperature HDT
°C
155
Thermal Heat Expansion Coefficient
1.1
Thermal Conductivity
W/(m×K)
< p>031Friction coefficient
0.35
The combination of these is:,?6?1 High fatigue strength.
6?1 Good abrasion resistance and very excellent friction performance. 6?1 Low water absorption. 6?1 High surface hardness and good rigidity. 6?1 Good dimensional stability and high dimensional accuracy of the product. 6?1 Good sliding.Polypropylene sheet: a thermoplastic resin produced by the polymerization of propylene. There are isotropic, atropic and mesotropic three configurations, industrial products to isotropic as the main component. Polypropylene also includes propylene and a small amount of ethylene **** polymer. Usually translucent colorless solid, odorless and non-toxic. Due to the structure of the regular and highly crystallized, so the melting point of up to 167 ℃, heat-resistant, products can be sterilized by steam is its outstanding advantage. Density 0.90g/cm3, is the lightest general-purpose plastic. Corrosion resistance, tensile strength of 30MPa, strength, rigidity and transparency are better than polyethylene. Disadvantages are poor low-temperature impact resistance, easier to age, but can be overcome by modification and addition of antioxidants, respectively.
Characteristics:
Non-toxic, odorless, low density, strength, rigidity, hardness and heat resistance are better than low-pressure polyethylene, can be used at about 100 degrees. It has good electrical properties and high-frequency insulation not affected by humidity, but becomes brittle at low temperatures, not wear-resistant and easy to aging. Suitable for the production of general mechanical parts, corrosion-resistant parts and insulating parts. Common acids, alkalis and organic solvents have little effect on it, and it can be used for eating utensils.
Production methods:
① Slurry method. Polymerization in diluent (such as hexane), is the earliest industrialized and by far the largest production method. ② Liquid phase native method. Polymerization in liquid propylene at 70℃ and 3MPa. ③ Gas phase method. Polymerization of propylene in a gaseous state. The latter two methods do not use diluents, have short processes and low energy consumption. The liquid-phase propriety method has now shown later advantages.
Molding characteristics:
1. Crystalline material, hygroscopic, easy to melt rupture, easy to decompose in contact with hot metal for a long time.
2. Good fluidity, but shrinkage range and shrinkage value is large, easy to occur shrinkage hole. Dents, deformation.
3. Cooling speed, pouring system and cooling system should be slow heat dissipation, and pay attention to control the molding temperature. Material temperature low temperature and high pressure is easy to orientation, mold temperature is lower than 50 degrees, the plastic is not smooth, easy to produce poor fusion, flow marks, more than 90 degrees prone to warping and deformation
4. Plastic wall thickness should be uniform, to avoid the lack of glue, sharp corners, in order to prevent the concentration of stress.
Uses
Engineering polypropylene fibers
Polypropylene monofilament fiber and polypropylene mesh fiber
Polypropylene mesh fiber modified polypropylene as raw material, through extrusion, stretching, netting, surface modification, such as short-cutting and other processes and become a high-strength bundled monofilament or mesh organic fibers, the intrinsic resistance to strong acid, alkali, weak thermal conductivity, with extremely stable and stable. Its inherent strong acid resistance, alkali resistance, weak thermal conductivity, with extremely stable chemical properties. Add concrete or mortar can effectively control the concrete (mortar) solid plastic shrinkage, dry shrinkage, temperature changes and other factors caused by micro-cracks, to prevent and inhibit the formation and development of cracks, and greatly improve the crack-blocking and seepage-resistant properties of concrete, impact resistance and seismic capacity, can be widely used in underground waterproofing, industrial and civil construction projects such as roofing, walls, flooring, pools, basements, etc., as well as roads and bridges. bridge projects. It is the new ideal material for mortar/concrete engineering anti-cracking, anti-seepage, wear-resistant, heat preservation
Biaxially oriented polypropylene film
Packaging materials occupy an extremely important position in plastic products, according to statistics, the world's plastics used in the field of packaging accounted for about 35% of the total consumption of plastics. China's rapid development of plastics for packaging, production from 1980, 190,000t quickly increased to 4.65 million tons in 2003, is expected to exceed 5.5 million tons in 2005, more than 7 million tons in 2010, more than 9 million tons in 2015, accounting for more than 13% of the country's total output of packaging.
From the product point of view, packaging film accounts for about 50% of the total packaging plastics. China's biaxially oriented polypropylene (BOPP) film is one of the largest areas of consumption of PP resin, in 2003, China has 86 BOPP manufacturers (123 production lines), with a total production capacity of about 1.4 million t / a, in 2004 to reach 2 million t / a (138 production lines), the output will break through the 1 million t. In recent years, the domestic enterprises to focus on improving the competitiveness of their products. Has introduced a number of advanced BOPP production equipment, the production of film width up to 8.3m, line speed up to 400-500m/min, such as Zhejiang Dazhongnan Group introduced the German Bruckner 60,000t / a production line; Guofeng Group invested 200 million yuan to introduce the 35,000t / a production line (currently Asia's first, the world's fourth 10m wide BOPP equipment); Changzhou, Wujin Jin Group introduced Germany 20,000t / a five-layer *** extrusion of high-strength ultra-thin BOPP production line; Fujian Modern Group introduced 25,000t / a production line; Baoshuo Group plans to introduce 100,000t / a production line and so on. According to China's existing BOPP film production capacity conversion, the annual demand for PP resin nearly 2 million tons, so attention should be paid to the development of BOPP film with high line speed, extensibility, transparency and good PP special materials, including supporting the use of ethylene and propylene **** polymer to adapt to the new introduction of BOPP film equipment.
Modified polypropylene for automotive
In 2003, China's automobile production of more than 4.4 million units, has ranked fourth in the world, an increase of 36.6%. According to the U.S. ESM WerWide reported: "China's automobile production in 2008 will exceed 6 million units, 2015 will exceed Japan, jumped to the world's second place".
The development of the automotive industry is inseparable from the process of automotive plastics, the current self-sufficiency rate of engineering plastics in China is less than 16%. According to the China Engineering Plastics Association predicted that China's engineering plastics demand growth rate of 15% in 2005, about 10% in 2010, the demand will grow from 440,000t in 2000 to 1.4 million t in 2010. China's automobile manufacturing industry on the rapid growth in demand for engineering plastics, the total amount of use by 2010 will reach 940,000t (to the amount of plastics accounted for the weight of the automobile 5%~10%)
Plastic is used in the manufacture of automobiles.
PP used in the automotive industry has a strong competitiveness, but because of its modulus and heat resistance is low, poor impact strength, so can not be directly used as automotive parts, cars in the use of modified PP products, its heat resistance can be increased from 80 ℃ to 145 ℃ ~ 150 ℃, and can withstand high temperatures of 750 ~ 1,000h after not aging, not cracking. Reportedly, Toyota Japan launched a new generation of highly oriented crystalline polypropylene HEHCPP products, can be used as automotive instrument panels, bumpers, than TPO as raw material for the production of similar products to reduce the cost of 30%, modified PP used as automotive parts has a very broad development prospects.
Household appliances with polypropylene
In recent years, China's household appliances industry is developing rapidly, with many varieties and large output. 2003 China's refrigerator production of 18.5 million units, 42 million air conditioners, washing machines 17 million units, microwave ovens 35 million units. According to the "2004~2006 China Urban Home Theater Market Research and Consulting Report", it is expected that in the next three years China's home theater system market size will reach 6.9 million units. In addition, a variety of small appliances also has a huge potential market, which is an excellent business opportunity for modified PP. At present, some of China's plastic raw materials manufacturers have developed special materials for washing machines such as PP 1947 series, K7726 series, etc., which are welcomed by washing machine manufacturers. Therefore, in the next few years should increase the development of PP special materials for household appliances to meet the changing needs of the market.
Polypropylene for pipes.
In 2003, the national total output of plastic pipes exceeded 1.8 million tons, an increase of 23%. Early, PP pipe is mainly used as agricultural water pipeline, but due to early product performance there are still some problems (impact strength, aging resistance is poor), the market failed to open. With the Shanghai Plastic Building Materials Factory was the first to introduce advanced foreign technology, the use of imported PP-R materials produced by the transmission of cold and hot water with the pipe is recognized by the market, there have been many manufacturers to build PP-R pipe production line, the price is also put into production by the early 20,000 ~ 30,000 yuan / t continued to fall, but PP-R pipe in the plastic pipe market share is still very low. It is reflected that the current domestic PP-R materials and imported materials still have a certain gap, the quality needs to be improved and enhanced. It is reported that South Korea has developed a high-pressure water supply pipe with no rules **** polypropylene PP-R 112 new grade, the use of the grade production of pipes can be in 20 ℃ and 11.2MPa ultra-high-pressure state of use for 50 years.
Plastic pipe is China's chemical building materials to promote the application of one of the key products, the Ministry of Construction was issued in 2001 "on strengthening *** polypropylene (PP-R, PP-B) pipe production management and promotion of the application of the work of the notice", requiring the relevant departments *** with the do a good job from raw materials, processing, quality to the use of pipe, installation and so on. Pipe use, installation and other work, we must strictly good PP pipe quality, in order to better do a good job in China's PP pipe production, application, promotion work.
Highly transparent polypropylene
As people's living standards continue to improve, will inevitably bring different changes in culture, entertainment, food, medical, materials, home decoration and other aspects of the requirements and improve the market for many items more and more use of transparent materials. Therefore, the development of transparent PP special materials is a good development trend, especially the need for high transparency, good fluidity, fast molding PP special materials, in order to design and process into people's favorite PP products. Transparent PP has more characteristics than ordinary PP, PVC, PET, PS, and has more advantages and development prospects.
In recent years, foreign transparent PP market is growing rapidly, such as South Korea's LG will be transparent PP as a PET alternative to the market; Germany, some companies use transparent PP instead of PVC; the United States, transparent PP products, the growth rate is higher than the ordinary PP products 7% to 9%; Japan in recent years, the annual consumption of PP nucleating transparent agent is about 2,000t, if the amount of additive 0.25% projected that the annual output of Japan's transparent PP material can reach up to 1,000t. The annual output of transparent PP material can reach more than 800,000t. According to the Japanese Ricoh Co., Ltd, Japan's transparent PP special materials for microwave cookware and furniture in two areas of the largest consumption. It is expected that in 2005, the foreign market demand for transparent PP special material is about 5 million to 5.5 million t. At present, the gap between domestic transparent PP special material and foreign countries is large, transparent PP resin and its products, the production and application of still need to be strengthened.
Polyethylene polyvinyl chloride polystyrene polypropylene What is the difference between polyethylene PE
Uncolored milky white semi-transparent, waxy; touch the products have a slippery feeling, soft and tough; slightly elongated. General low-density polyethylene is softer, better transparency; high-density polyethylene is harder.
Common products: handbags, water pipes, oil drums, beverage bottles (calcium milk bottles), daily necessities and so on.
Polypropylene PP
Uncolored white translucent, waxy; lighter than polyethylene. Transparency is also better than polyethylene, rigid than polyethylene.
Common products: pots, buckets, furniture, film, woven bags, bottle caps, car bumpers, etc..
Polystyrene PS
Transparent when not colored. Products fall to the ground or knock, there is a metal-like crisp sound, gloss and transparency is very good, similar to glass, brittle and easy to break, with fingernails can be scratched on the surface of the product. Modified polystyrene is opaque.
Common products: stationery, cups, food containers, home appliance shells, electrical fittings, etc.
Polyvinyl Chloride PVC
The original color is yellowish translucent, shiny. Transparency better than polyethylene, polystyrene, worse than polystyrene, with different amounts of additives, divided into soft and hard PVC, soft products are soft and tough, sticky feel, hard products, the hardness is higher than the low-density polyethylene, but lower than the polypropylene, in the bending place there will be whitening phenomenon.
Common products: plates, tubes, shoe soles, toys, doors and windows, wire sheaths, stationery, etc.
Polyethylene terephthalate PET
Very good transparency, strength and toughness is better than polystyrene and polyvinyl chloride, not easy to break.
Common products: often bottle products such as Coke, mineral water bottles, etc.