What is paraffin wax?

Paraffin wax is a kind of mineral wax, is also a kind of petroleum wax; it is from the crude oil distillation of lubricating oil fractions obtained by solvent refining, solvent dewaxing, or by wax freeze crystallization, press dewaxing wax paste, and then solvent degreasing, refining, and obtained by the flaky or needle-like crystals. Also known as crystalline wax, the number of carbon atoms of about 18 ~ 30 hydrocarbon mixture, the main component for the straight chain alkanes (about 80% ~ 95%), there are a small number of alkanes with individual branched chain and with long side chain of the monocyclic cyclohexane (the two combined content of 20% or less).

Paraffin wax - basic information

Paraffin wax

Paraffin wax, also known as crystalline wax, the number of carbon atoms of about 18 to 30 of the hydrocarbon mixture, the main component for the straight-chained alkanes (about 80% to 95%), and a small number of alkanes with individual branched chain and a long side chain of the monocyclic cycloaliphatic hydrocarbons (the two combined content of less than 20%). Paraffin is a flaky or needle-like crystal obtained from the lubricating oil fraction distilled from crude oil by solvent refining, solvent dewaxing or wax freeze crystallization, press dewaxing, and then by oil removal and additional refining. According to the different degree of processing and refining, can be divided into fully refined paraffin wax, semi-refined paraffin wax and crude paraffin wax 3 kinds. Each type of wax and according to the melting point, generally every 2 ℃, divided into different varieties, such as 52, 54, 56, 58 and other grades. Crude paraffin wax has a high oil content and is mainly used in the manufacture of matches, fiber boards, tarpaulins and so on. Fully refined paraffin wax and semi-refined paraffin wax has a wide range of uses, mainly used as food, oral medicines and certain commodities (such as wax paper, crayons, candles, copy paper) components and packaging materials, baking containers for coating materials, for fruit preservation, insulation of electrical components, to improve the aging resistance of rubber and to increase the flexibility and so on. It can also be used to generate synthetic fatty acids by oxidation.

In chemistry, paraffin is the common name for a mixture of solid higher alkanes with the molecular formula CnH2n+2, where n=20-40. paraffin 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 some esters. Paraffin wax does not react with common chemical reagents, but it can burn.

Pure paraffin is a good insulator, with a resistivity of 1013-1017 ohm-m[2], higher than most materials except some plastics (especially Teflon). Paraffin is also an excellent 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 a major component of candles.

There are a few claims about the chemical symbols of paraffin wax, one of which is that the main component of paraffin wax is a mixture of substances of the elements C and H. (It may contain the element oxygen, but this is not the case with paraffin wax. (may contain oxygen, but this is not the main) its chemical element symbol for CxHy. Another saying is that paraffin wax is a mixture of several kinds of high-level alkanes, mainly twenty-two alkanes (C22H46) and twenty-eight alkanes (C28H58), containing carbon element about 85%, containing hydrogen element about 14%. There is no single chemical element symbol.

The main quality indicators of paraffin wax are melting point, which indicates temperature resistance, and oil content, which indicates purity. Each type of wax and according to the melting point, generally every 2 ℃, divided into different varieties, such as 52, 54, 56, 58 and other grades. According to the different degree of processing and refining, can be divided into fully refined paraffin wax, semi-refined paraffin wax and crude paraffin wax 3 kinds. Among them, the former two are more widely used, mainly used as food and other commodities (such as wax paper, crayons, candles, copy paper) components and packaging materials, baking containers, coating materials, cosmetic raw materials, used for fruit preservation, to improve the rubber anti-aging properties and increase flexibility, insulation of electrical components, precision casting, etc., but also can be used for oxidation to generate synthetic fatty acids. Crude paraffin is mainly used in the manufacture of matches, fiber boards, tarpaulins and so on due to its high oil content. Paraffin wax in the addition of polyolefin additives, its melting point increases, adhesion and flexibility increased, widely used in moisture-proof, waterproof wrapping paper, cardboard, some textiles surface coating and candle production.

Paraffin Wax - Paraffin Slices

Making of Paraffin Slices

Paraffin Slices

Slices made from paraffin wax can be made extremely thin. The general thickness of the section is required to be 4-6 microns. Paraffin slices can not only meet this requirement, but can even be sliced thinner to 2 microns to 1 micron. This is a result that is difficult to obtain with frozen slices and fire-cotton gel slices. In addition, paraffin sections facilitate the production of large or continuous sections. Moreover, paraffin-embedded tissue blocks are easy to store for long periods of time. Therefore, paraffin sectioning is one of the most commonly used methods in the production of various sectioning methods.

-Preparation before sectioning

1, preheat the thermostatic water bath to 35℃-40℃ first.

2. The wax block was trimmed, and the paraffin on the tissue side of the block was trimmed away with a knife so that all the tissue was exposed to the cut surface and trimmed flat to reduce the wear of the sectioning knife. The paraffin on the left and right sides of the block is removed without damaging the tissue or affecting the diagnosis; otherwise, the section will be easily wrinkled. The paraffin on the upper and lower edges of the tissue block should be trimmed and flattened according to the tissue condition; the paraffin should not be left too much, but as little as possible to keep the spacing between the tissues to a minimum. The slices cut in this way are neither banded nor curved. If the distance between the slices is small, more slices can be patched accordingly, which is conducive to the examination and diagnosis. When trimming the wax block, the wax edge can only be cut off bit by bit, if a large area is trimmed, it is easy to make the wax block break and expose the tissue; in this case, it should be returned to the new wax and embedded again.

3. The slides should be washed and cleaned beforehand, free of grease and opacity, and should be immersed in an acid bath for 12 hours, then rinsed under running water and baked dry. According to the number of slices needed, each slice coated with a very thin layer of protein glycerin, inserted in the carrier plate (or carrier frame) on the standby. Preparation of protein glycerol: take 1 part of fresh egg and 1 part of glycerol, then add appropriate amount of muscimol and stir well. The main purpose of this method is to prevent dislodgement, in fact, a very clean slide will not be dislodged without applying protein glycerin.

4, the sharp blade into the slicing knife clamp, adjust the angle and position and then tighten, check whether the inclination of the slicing knife is correct, tilt angle is too large, the slices on the roll; tilt angle is too small, the slices are wrinkled, 20 ° - 30 ° is better.

5, spare small brush, small hookless tweezers, pencil.

-Steps in slicing

1, the wax block is fixed in the holder on the head of the slicer, and adjusted to a position slightly away from the slicer to be able to cut into, paying attention to the wax block tissue cut surface and the slicing blade to be perpendicular and parallel.

2. Adjust the cut surface of the wax block to be in contact with the blade, tighten the blade holder, and fix the machine head.

3. Adjust the thickness of the slices as needed.

4, shake the slicer handwheel to trim the slices first, until the complete maximum tissue cut surface is cut.

5.In practice, the slicer handwheel can be rotated with the right hand, and the left hand can hold up the wax slice with a brush to perform the slicing operation in a coordinated manner.

6, cut the slicing tape, one end of the tweezers gently pulled up, should be straightened as much as possible to unfold the slicing tape, the slicing tape with a brush from the knife mouth upward to pick up, pull down the slicing tape, and then gently drag to spread on the thermostatic water surface.

-Slicing notes

1, the quality of slicing, in addition to technical proficiency and slicing machine is good or bad, slicing knife is the deciding factor, so the knife must be sharpened very sharp. Otherwise in the slicing will roll up or wrinkled, or the organization will scratch the knife marks, and more can not be cut into a continuous long strip of smooth slicing. Slicing knife, such as the existence of a gap, will make the slices made of broken, broken, incomplete, slicing should be wiped clean when the knife.

2, slicer parts and screws should be screwed tightly, otherwise it will produce vibration. In each replacement of the wax block, it should be customary to check whether the tissue block is clamped, slicing knife is solid, a little negligence will affect the quality of slicing, and even the wax block all cut bad, resulting in irreparable consequences. The most common cause of poor slicing and other malfunctions at the beginning of slicing is the loosening of the wax block or the slicing knife.

3, in shaking the slicer, the force requires uniformity, should not be too heavy and fierce, otherwise the body can be too heavy and make the machine vibration, resulting in uneven thickness of the slice. In the event of excessive hardening of the brain, liver, spleen and other tissues, it should be more gently cutting, in order to prevent the formation of tissue due to the vibration of the hollow phenomenon.

4, in the summer and fall seasons for slicing, should use ice to strengthen the cooling, so that not only can maintain the hardness of paraffin, but also reduces the folds of the slices, to the slicing of the production of convenience.

-Slice

1, will be single or several slices, with tweezers clamp the side of the wax slice and lift, spread in constant temperature water, (shiny side down) immediately with a brush gently stretched to the slices without wrinkles for the best. If there are wrinkles, gently remove them one by one with forceps, taking care not to break the tissue. Then separate each slice and select the most complete, wrinkle-free slice.

2. After the sections are fully spread out and flattened in the thermostatic water, insert the slide vertically into the water with the glycerin-coated side of the slide, and use the brush to set one side of the section on the slide, then lift the slide upright, and while there is still a small amount of water on the slide, use the brush to set the correct position of the section. If the tissue is small, you can put a few more slices or rows on the slide, but the arrangement should be dense and neat.

3, with a pencil at one end of the slide on the hair glass to write the specimen number, the word should be written in a small but clear, upright.

4, will be attached to a good section of the paste placed in 60 ℃ constant temperature oven drying 2 hours, protein coagulation can be stained.

Paraffin - liquid paraffin

Liquid paraffin

Chemical structure: melting point below 40 ℃ than from C10 to C18 of a variety of n-alkanes composed of a mixture. Sometimes white oil is also become liquid wax. But there is a clear difference in structure.

Production process: kerosene, diesel oil and other light distillates after molecular sieve and cold press dewaxing, concentrated sulfuric acid refining, alkali washing, water washing

Properties: non-absorbent, electrically insulating

Main uses: detergent raw materials, cosmetics, daily necessities diluent, solvents and so on

Based on the distillate, it can be divided into (light) liquid paraffin wax and heavy liquid paraffin wax, and C11 to C18 of various n-alkane monomers or mixtures of several n-alkanes. Each n-alkane has different volatile properties, kinematic viscosity, and thus derives various applications.

Paraffin Waxes - An Introduction

Microcrystalline Paraffin Waxes

Hydrocarbons used as lubricants are a number of aliphatic hydrocarbons with molecular weights of 350 or more, including paraffin waxes, synthetic paraffin waxes, low molecular weight polyethylene waxes, and mineral oils. Practical hydrocarbon lubricants are mixtures of hydrocarbons that have a specific molecular weight, viscosity, or melting range. Hydrocarbon lubricants are excellent external lubricants but are not ideal internal lubricants because of their poor compatibility with polymers.

-Paraffin wax

The main components are straight-chain alkanes with small amounts of branched-chain alkanes. The straight chain alkane content varies from 75% to nearly 100%. Paraffin is a white group that is soluble in a class of non-polar solvents such as benzene, chloroform, carbon tetrachloride, and naphtha, and insoluble in polar solvents such as water and methanol.

-Microcrystalline paraffin wax

Microcrystalline paraffin wax is mainly composed of hydrocarbons, naphthenic hydrocarbons and some straight-chain hydrocarbons, and its molecular weight ranges from about 500 to 1,000. it is a relatively fine crystal, soluble in non-polar solvents, insoluble in polarizing agents.

-Liquid paraffin wax

There are many types of liquid paraffin waxes, and their lubricating effects vary. In the extrusion process, the initial lubrication effect is good, the thermal stability is also good. However, due to poor compatibility, the products are easy to stick when the dosage is too much.

-Polyethylene wax (ACPE)

Polyethylene wax refers to low molecular weight polyethylene with molecular weight of 1500-25000 or partially oxidized low molecular weight polyethylene. It is in the form of granules, white powder, lumps and milky white wax. It has excellent fluidity, electrical properties, and mold release.

Paraffin Wax - Introduction to Uses

Paraffin Wax

Paraffin wax is very versatile. Paper dipped in paraffin wax can be produced with good waterproof performance of various wax paper, can be used for food, pharmaceuticals and other packaging, metal rust and printing industry; paraffin wax added to cotton yarn, can make the textiles soft, smooth and flexible; paraffin wax can also be produced detergents, emulsifiers, dispersing agents, plasticizers, grease the most and so on.

Now, there are a variety of different paraffin products on the market. Wax products based on polyethylene, polypropylene and Brazilian wax are most commonly used in coatings and inks. Wax products based on polytetrafluoroethylene (PTFE) are also used as matting agents.

In contrast to silica, paraffin waxes modify the paint film by floating on the outermost surface. This also affects the following properties: matting/gloss; anti-slip and anti-fouling; anti-adhesion and anti-abrasion, anti-settling and anti-surface tension.

Most of these products are micronized to allow them to be used in a wide range of concentrations in wax emulsion based coatings. Their dispersibility varies depending on particle size and particle size distribution.