Paraffin wax is a strange wax extracted from certain pavilions of petroleum, shale oil, or other bituminous mineral oils. It is a white or light yellow translucent with a fairly pronounced crystal structure. Another character paraffin.
Basic Information
Petroleum wax
English name:paraffin wax
CAS registration number: 8002-74-2
EINECS accession number: 232-315-6
Introduction
Paraffin wax is a kind of mineral wax, and it is also a kind of petroleum wax; it is obtained by solvent refining, solvent dewaxing or wax freezing crystallization from the crude oil fraction obtained by distillation of crude oil, pressing and dewaxing to obtain wax paste, and then solvent removal. Oil or refined flakes or needles. Also known as crystalline wax, a mixture of hydrocarbons with about 18 to 30 carbon atoms, the main component is a linear alkane (about 80% to 95%), and a small amount of alkanes with individual branches and long side chains Monocyclic cycloalkanes (total content of both is 20% or less). The main quality indicators are the melting point and the oil content, the former indicates the temperature resistance and the latter indicates the purity. Among them, the former two are widely used and are mainly used as components and packaging materials for foods and other commodities (such as wax paper, crayons, candles, and carbon paper), coating materials for baking containers, and cosmetic raw materials, which are used for keeping fruits fresh and improving rubber resistance. Aging and increased flexibility, electrical component insulation, precision casting, etc., can also be used to oxidize to produce synthetic fatty acids.
classification
According to the different degree of processing refinement, it can be divided into three kinds of fully refined paraffin, semi-refined paraffin and crude paraffin. Each type of wax, in turn, is divided into different types, such as 52, 54, 56, 58 and other grades, according to the melting point, generally every 2 °C. Crude paraffin wax has a high oil content and is mainly used to make matches, fiberboards, awnings, etc.
·paraffin
The main component is a linear alkane and contains a small amount of branched alkane. Linear alkane content varies from 75% to nearly 100%. Each specific species consists of approximately 8-15 alkanes of different carbon numbers. Paraffin is a white group, soluble in gasoline, carbon disulfide, xylene, ethyl ether, benzene, chloroform, carbon tetrachloride, naphtha and other non-polar solvents, insoluble in polar solvents such as water and methanol.
·Microcrystalline wax
Microcrystalline waxes are mainly composed of chain-stranded hydrocarbons, naphthenes, and some straight-chain hydrocarbons with a molecular weight range of about 500-1000. This is a relatively fine crystal, soluble in nonpolar solvents, insoluble in polar lattices.
Liquid paraffin
There are many types of liquid paraffin and their lubricating effects are also different. In the initial stage of the extrusion process, the lubrication effect is good and the thermal stability is also good. However, due to poor compatibility, the product tends to become sticky when used in excessive quantities.
Polyethylene wax (ACPE for short)
Polyethylene wax refers to low molecular weight polyethylene or partially oxidized low molecular weight polyethylene having a molecular weight of 1500-25000. It is in the form of granules, white powder, lumps and milky white waxes. Has excellent fluidity, electrical properties, mold release.
Semi-refined paraffin
It is a granular white solid. Its relative density increases with the increase of melting point. The product has good chemical stability, moderate oil content, good moisture and insulation properties, and good plasticity. Candles produced from semi-refined paraffin wax are flame concentrated, smoke-free, not Tears. Used in candles, crayons, wax paper, general telecommunications equipment, short circuit and light industry, chemical raw materials.
Chemical properties
In chemistry, paraffin wax is the common name for solid higher-alkane mixtures, with the formula CnH2n+2, where n=20-40. A mixture of hydrocarbons having about 18 to 30 carbon atoms, the main component of which is a linear alkane (about 80% to 95%), and a small amount of alkane with a single branch and a monocyclic cycloalkane with a long side chain ( The total content of both is less than 20%). Paraffin wax does not react with common chemical reagents, but it can burn.
Physical properties
Paraffin, also known as crystalline wax, is usually a white, colorless, odorless waxy solid with a melting point of 47°C-64°C and a density of about 0.9 g/cm3. It is insoluble in water but soluble in ether, benzene and certain esters. Pure paraffin is a good insulator with a resistivity of 1013-1017 ohm-meters [2], which is higher than most materials except certain plastics (especially Teflon). Paraffin is also a very good heat storage material, with a specific heat capacity of 2.14–2.9 J·g–1·K–1 and a heat of fusion of 200–220 J·g–1. Paraffin is the main ingredient of candles.
Element symbol
There are several arguments about the symbol of the chemical element of paraffin wax. One theory is that the paraffin wax is composed of a mixture of C and H elements. (may contain oxygen, but this is not the main) The chemical symbol is CxHy. Another argument is that paraffin is a mixture of several higher alkanes, mainly n-dodecane (C22H46) and n-octacosane (C28H58), containing about 85% of carbon and about 14% of hydrogen. There is no single chemical. Element symbol.
Slice production
Paraffin sections Slices made of paraffin can be made into extremely thin sections. The typical slice thickness is 4-6 microns. The paraffin section can not only meet this requirement, but can even be cut to 2 microns or even 1 micron. This is the result of the hard-to-obtain results of frozen sections and pieces of jelly rubber. In addition, paraffin sections also facilitate the production of large or continuous sections. And paraffin-embedded tissue blocks facilitate long-term preservation. Therefore, paraffin sections are the most commonly used method in various slice preparation methods.
· Preparation before slicing
1. Constant temperature water bath first preheated to 35 °C -40 °C.
2. The wax block was repaired and the wax on the tissue surface of the wax block was repaired with a knife to expose all the sections of the tissue and trimmed to reduce the wear of the slicing knife. The paraffin on the left and right sides of the tissue block was completely removed on the principle of not damaging the tissue and affecting the diagnosis; otherwise, the slice was easily wrinkled. The paraffin tissue at the top and bottom edges of the tissue block is trimmed and repaired; the paraffin need not be left too much and should be kept as little as possible to maintain the minimum tissue spacing. The slices thus cut are banded and do not bend. The film is small, and it can be patched more when it is patched, which is helpful for inspection and diagnosis. When the wax block is trimmed, the wax edge can only be cut off little by little. If a large piece is repaired and cut, the wax block will break to expose the tissue; in this case, the new wax should be returned and embedded again.
3. The slides should be washed in advance without greasy or opaque phenomenon. The slides should be immersed in the acid tank for 12 hours and rinsed with water. According to the number of slices required, each sheet is coated with a thin layer of protein glycerol and placed on a slide plate (or slide holder) for later use. Preparation of protein glycerol: Take 1 part of fresh egg and 1 part of glycerol, and mix well with thymol. This method is mainly to prevent dislodging. In fact, a very clean slide will not be stripped without protein glycerin.
4. Insert the sharp blade into the slicing blade clamp and tighten it immediately after adjusting the angle and position. Check whether the slicing knife's tilt is correct. If the tilt angle is too large, then slice it up. If the tilt angle is too small, the slice will wrinkle. 20°-30° is preferred.
5 spare small brush, small hookless tweezers, pencil.
· Steps for slicing
1. Fix the wax block in the holder on the slicer head and adjust it to a position slightly away from the slice. Note that the cut surface of the wax block should be perpendicular to the slice edge.
2. Then adjust the cut surface of the wax block to just contact the knife edge, tighten the knife holder, and fix the machine head.
3. Adjust the slice thickness as needed.
4. Shake the slicer The hand wheel is first trimmed and cut until it is cut out of the largest tissue section and then cut.
5. In practice, the right hand can be used to turn the hand wheel of the slicer, the left hand holds the wax slice with a brush, and the slice operation is performed in a coordinated manner.
6. Cut the slicing tape, and gently pull up one end with tweezers. Straighten the slicing tape as straight as possible. Use a brush to pick up the slicing tape from the knife edge, pull down the slicing tape, and then gently wrap it on the constant-temperature water. .
· Slice notes
1. In addition to the quality of the slicing, the slicing knife is the deciding factor, in addition to the technical proficiency and the quality of the slicer. Therefore, the knife must be sharply ground. Otherwise, it will curl up or wrinkle on its own, or it will scratch the tissue, and it will not cut the slice into a continuous strip. If there is a gap in the slicing knife, the prepared slice will be broken and broken, and the slice will be incomplete. When cutting, the knife edge should be wiped from time to time.
2. All parts and screws of the slicer should be tightened, otherwise vibration will occur. Every time you change the wax block, you should be accustomed to checking whether the tissue block is clamped or not, whether the slicing knife is stable, slight neglect will affect the quality of the slice, and even cut the wax block completely, resulting in irreparable consequences. The most common cause of poor cuts and other failures at the beginning of the cut section is the looseness of the wax block or slicing knife.
3. When the slicer is shaken, the force is required to be even and consistent, and it should not be too heavy and too fierce. Otherwise, the body may vibrate due to excessive force, resulting in uneven thickness of the slice. In case of excessive hardening of the brain, liver, spleen and other tissues, it should be lightly cut to prevent the formation of hollow tissue due to vibration.
4. During the slice in summer and autumn, ice cubes should be used for cooling. This not only maintains the hardness of paraffin, but also reduces the folds of the slices, which facilitates the production of the slices.
· Patch
1. Cut a single leaf or slices, use a tweezers to hold the side of the wax and lift it up. Spread it in a constant temperature water (bright side down) and use a brush to gently stretch it to make it wrinkle-free. If there is wrinkle, carefully poke them one by one carefully with a forceps, taking care not to break the tissue. Then divide each slice and select the most complete, unfolded slice.
2. Wait until the slices are fully spread in the constant temperature water. After inserting the slides vertically into the water, apply the protein glycerol surface to the slices and cut them on the glass slides with a brush. Then slide the slides upright. When there is still a small amount of moisture on the tablet, use a brush to set the slice position. If the organization is small, you can put several or several rows on the slide, but the arrangement should be dense and tidy.
3. Use a pencil to write the specimen number on the frosted glass at the end of the slide. The word should be small, clear, and correct.
4. The attached slices were placed in a 60°C incubator and dried for 2 hours. After the proteins were coagulated, they were stained.
The main purpose
Crude paraffin wax is mainly used for making matches, fiberboards, tarpaulins, etc. due to its high oil content. The addition of polyolefin additives to paraffin waxes increases the melting point, increases the adhesion and flexibility, and is widely used for moisture-proof, waterproof packaging paper, cardboard, surface coating of certain textiles, and candle production.
After immersing the paper in paraffin, various wax papers with good waterproof properties can be prepared, which can be used for packaging of foods, medicines, metal rust prevention and printing industries; after the wax is added to cotton yarns, the textiles can be soft, smooth and elastic. Paraffin can also be made into detergents, emulsifiers, dispersants, plasticizers, greases, etc. As the resources for animal waxes and vegetable waxes have become more and more intense, most candles are now made of paraffin wax. Paraffin wax melts when it is heated, it glows when it burns, it emits black smoke, and it emits heat.
The use of paraffin waxes and semi-refined paraffin waxes is very versatile. It is mainly used as a component of foods, oral medicines and certain commodities (such as wax paper, crayons, candles, carbon paper) and packaging materials, as well as coating materials for baking containers for fruit preservation. , Insulation of electrical components, improve rubber anti-aging properties and increase flexibility. It can also be used to oxidize to produce synthetic fatty acids.
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