Polycarbonate
polycarbonate (PC) is a kind of polymer with carbonate group in the molecular chain, which can be divided into aliphatic, aromatic, aliphatic aromatic and other types according to the structure of ester group. Because of the low mechanical properties of aliphatic and aliphatic aromatic polycarbonates, their applications in engineering plastics are limited. At present, only aromatic polycarbonate has been industrialized. Due to the special structure of polycarbonate, it has become the fastest growing general engineering plastics among the five engineering plastics
physical properties
density: 1.20-1.22 g / cm linear expansion rate: 3.8 × 10 cm/cm ° C hot deformation temperature: 135 ° C
polycarbonate is colorless, transparent, heat-resistant, impact resistant, flame retardant, Bi grade, and has good mechanical properties at ordinary service temperature. Compared with polymethylmethacrylate, polycarbonate has good impact resistance, high refractive index, good processability, and UL94 V-0 flame retardancy without additives. However, the price of PMMA is lower than that of polycarbonate, and large devices can be produced by bulk polymerization. With the expansion of polycarbonate production scale, the price difference between polycarbonate and polymethylmethacrylate is narrowing
it is not resistant to strong acid and alkali, and the modified polycarbonate can be resistant to acid and alkali
the wear resistance of polycarbonate is poor. Some polycarbonate devices for wear-resistant applications need special surface treatment
the application and development of polycarbonate is developing in the direction of high composite, high function, specialization and serialization. At present, it has launched a variety of special grades of CD, automobile, office equipment, box, packaging, medicine, lighting, film and other products
(1) used in building materials industry. Polycarbonate sheet has good light transmittance, impact resistance, UV radiation resistance, dimensional stability and good processing performance, which makes it have obvious technical performance advantages over inorganic glass used in construction industry. At present, there are more than 20 polycarbonate hollow board production lines in China, with an annual demand of about 70000 tons of polycarbonate, which is expected to reach 140000 tons by 2005
(2) used in automobile manufacturing industry. Polycarbonate has good impact resistance, thermal distortion resistance, good weather resistance and high hardness, so it is suitable for the production of various parts of cars and light trucks, mainly in the lighting system, instrument panel, heating plate, defroster and polycarbonate alloy bumper. According to the data of developed countries, the proportion of polycarbonate vinegar used in the electronic and electrical industry and automobile manufacturing industry is 40% – 50%. At present, the proportion of China’s use in this field is only about 10%. The electronic and electrical industry and automobile manufacturing industry are the pillar industries of China’s rapid development, and the demand for polycarbonate vinegar in these fields will be huge in the future. 1t is estimated that the total number of vehicles in China will reach more than 3 million in 2005, and the demand will reach 30000 tons by then. Therefore, the application of polycarbonate in this field has great potential for expansion
(3) for the production of medical devices. Polycarbonate products are widely used in artificial kidney hemodialysis equipment and other medical equipment that need to be operated under transparent and intuitive conditions and need to be repeatedly disinfected because they can withstand steam, cleaning agent, heating and high-dose radiation disinfection without yellowing and physical performance degradation. Such as the production of high-pressure syringes, surgical masks, disposable dental appliances, blood separator, etc
(4) used in aviation and aerospace. 1n recent years, with the rapid development of aviation and aerospace technology, the requirements of aircraft and spacecraft components continue to improve, making the application of PC in this field is also increasing. According to statistics, only one Boeing aircraft uses 2500 polycarbonate components, and a single aircraft consumes about 2 tons of polycarbonate. On the spaceship, hundreds of polycarbonate parts with different configurations and reinforced by glass fiber and protective articles for astronauts are used
(5) used in packaging field. 1n recent years, the new growth point in the field of packaging is various types of water storage bottles that can be repeatedly disinfected and used. Due to the advantages of polycarbonate products, such as light weight, good impact resistance and transparency, no deformation and transparency when washed with hot water and corrosive solution, PC bottles have completely replaced glass bottles in some fields. 1t is predicted that with the continuous improvement of people’s attention to the quality of drinking water, the growth rate of polycarbonate consumption in this area will remain at more than 10%, and it is expected to reach 60000 tons by 2005
(6) used in the field of electronics. Polycarbonate is an excellent insulating material because of its good and constant electrical insulation in a wide range of temperature and humidity. At the same time, its good flame retardancy and dimensional stability make it form a broad application field in the electronic and electrical industry. Polycarbonate resin is mainly used in the production of various food processing machinery, electric tool shell, body, bracket, refrigerator freezer drawer and vacuum cleaner parts. Moreover, polycarbonate material also shows a high value in the use of important parts in computers, video recorders and color TV sets, which require high precision of parts< (7) used in the field of optical lens. Polycarbonate occupies an extremely important position in this field because of its unique characteristics of high transmittance, high refractive index, high impact resistance, dimensional stability and easy processing. The optical lens made of optical grade polycarbonate can be used not only for cameras, microscopes, telescopes and optical testing instruments, but also for film projector lens, copier lens, infrared auto focusing projector lens, excimer beam printer lens, various prism mirrors, polyhedral mirrors and many other office equipment and household appliances. 1ts application market is extremely broad. Another important application of polycarbonate in optical lens is as lens material for children's glasses, sunglasses, safety glasses and adult glasses. 1n recent years, the average annual growth rate of polycarbonate consumption in the world's glasses industry has been maintained at more than 20%, showing great market vitality
(8) basic materials for optical discs. 1n recent years, with the development of information industry, the optical disc made of optical grade polycarbonate is developing rapidly as a new generation of audio-visual information storage medium. Polycarbonate has become the main raw material of optical disc manufacturing industry in the world because of its excellent performance. At present, the consumption of polycarbonate in the world’s optical disc manufacturing industry has exceeded 20% of the total consumption of polycarbonate, with an average annual growth rate of more than 10%. According to the figures released by the State Administration of press and publication, there were 748 CD production lines in China in 2002, with an annual consumption of about 80000 tons of optical grade polycarbonate, all of which were imported. Therefore, the application prospect of polycarbonate in the field of optical disc manufacturing is extremely broad
cellulose acetate is also called cellulose acetate. Cellulose acetate is a synthetic fiber made from acetic acid and cellulose by esterification. The structural formula can be expressed as: (c6h7o2) (oocch3) 3N
usage
acetate fiber is not easy to catch fire, and can be used to manufacture textiles, cigarette filters, film base, plastic products, etc< 1. The physical and mechanical properties of acetate fiber
the density of acetate fiber is smaller than that of viscose fiber, which is close to that of polyester fiber; The residual strength is about 70% of the dry strength, which is similar to the wet strength of viscose. Therefore, in the process of drawing and wet processing of acetate fiber, we must take a mild way. However, the elongation at break of acetate fiber is higher than that of viscose, and the elongation in wet state is larger. Therefore, the elasticity of acetate fiber is relatively good, similar to silk and wool. Boiling water shrinkage is low, but high temperature treatment will affect the strength and luster of the fiber, so the temperature should not exceed 85 â„? Moisture regain is lower than viscose fiber, but much higher than polyester fiber, between viscose and polyester. That is to say, acetate fiber not only has a certain degree of water absorption, but also has the performance of rapid removal after water absorption. The softening temperature and melting point of acetate fiber are close to that of polyester fiber, which has similar thermal properties as synthetic fiber; The dry heat treatment under relaxation condition has no effect on the properties of the fiber
2. Chemical properties of acetate fiber
acetate fiber has good acid resistance and stability, and the common sulfuric acid, hydrochloric acid and nitric acid will not affect the strength, luster and elongation of the fiber in a certain concentration range; But it can be dissolved in concentrated sulfuric acid, concentrated hydrochloric acid and concentrated nitric acid. Acetate fiber is very sensitive to alkali agent, especially diacetate fiber, which is prone to deacetylation when it meets strong alkali. Blank T-shirt causes weight loss, strength and modulus also decrease. Therefore, the pH value of cellulose acetate solution should not exceed 7.0. Under the standard washing conditions, it has strong resistance to chlorine bleaching and can also be dry cleaned with tetrachloroethylene
3. Dyeing properties of cellulose acetate fiber
although cellulose acetate fiber comes from cellulose, in the esterification process, a large part of the polar hydroxyl group on the glucose ring of cellulose is replaced by acetyl group to form ester. Therefore, the dyes commonly used in cellulose fiber dyeing have almost no affinity for cellulose acetate fiber and are difficult to dye. Theoretically speaking, acetate fiber can be dyed with direct and reactive dyes after partial saponification and reduction of original hydroxyl. However, this is not feasible. 1n addition, because the carbonyl oxygen atoms and residual hydroxyl groups on cellulose acetate have a certain amount of negative charge, some people have also experimented with cationic dyes for dyeing diacetate fiber, but the results show that only light color can be obtained. The dyeing performance of acetate fiber is similar to that of polyester or nylon. Only finely dispersed non water soluble dyes can enter into acetate fiber at a certain temperature to dye the fiber. The most suitable dyes for acetate fiber are disperse dyes with low molecular weight and similar dye uptake rate. 1n fact, the birth of the first disperse dye was also due to the need of acetate fiber dyeing. The acetate fiber or fabric dyed with disperse dyes has bright color, good leveling effect, high dye exhaustion rate, high color fastness and complete chromatogram. The dyeing process of acetate fiber has a great influence on the dyeing effect, especially on the control of temperature. The lower the temperature, it is easy to cause endless dyeing; 1f the temperature is high, uneven dyeing will be caused due to fast dyeing. The dyeing process of acetate fiber fabric produced by this method is as follows:
auxiliaries: chelating agent 0.33 g / L, sodium dihydrogen phosphate 0.08 g / L, anionic detergent 0.07 g / L at 27 â„?br/>
pH value: 6.5 ~ 7.0
temperature: 71 â„? add dye, slowly raise temperature to 82 ~ 88 â„? dyeing
time: 60 min
drainage, cleaning
the blended fabric of acetate fiber and various natural or man-made fibers can be cross dyed, that is, the two-color effect can be produced in one bath dyeing. For pure acetate fabric, it should be dyed on a wide roll dyeing machine or a normal pressure warp dyeing machine to reduce fabric folding