The role and use of paraffin wax

2022-05-22   Pageview:85

The role and use of paraffin is to make matches, fiberboard, canvas and so on. After adding polyolefin additives to paraffin, its melting point is increased, adhesion and flexibility are increased, and it is widely used in moisture-proof and waterproof packaging paper, cardboard, surface coating of certain textiles and candle production.

Paraffin wax is a hydrocarbon mixture extracted from some distillates of petroleum, shale oil or other bituminous mineral oils. Paraffin is amorphous, but has a distinct crystalline structure, and there are artificial paraffins.

Paraffin wax is a kind of petroleum processing products, a kind of mineral wax, and a kind of petroleum wax. It is a flake or needle-like crystal obtained from the lubricating oil fraction obtained by distillation of crude oil through solvent refining, solvent dewaxing or wax freezing crystallization, pressing and dewaxing to obtain wax paste, and then solvent deoiling and refining. It is used to make higher fatty acids, higher alcohols, matches, candles, water repellants, ointments, electrical insulating materials, etc.

Paraffin is divided into food grade (food grade and packaging grade, the former is preferred) and industrial grade, food grade is non-toxic, and industrial grade is not edible.

physical properties

Paraffin wax, also known as crystalline wax, is usually a white, odorless waxy solid, melting at 47°C-64°C, with a density of about 0.9g/cm3, soluble in gasoline, carbon disulfide, xylene, ether, benzene, chloroform, tetrakis A class of non-polar solvents such as carbon chloride and naphtha, insoluble in polar solvents such as water and methanol. Pure paraffin is a good insulator, with a resistivity of 1013-1017 ohm-meter, which is higher than most materials except some plastics (especially Teflon). Paraffin is also a 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. The main performance indicators of paraffin are melting point, oil content and stability.

melting point
Paraffin is a mixture of hydrocarbons, so it does not have a strict melting point like a pure compound. The so-called melting point of paraffin refers to the temperature at which a stagnation period first appears on the cooling curve when a molten paraffin sample is cooled under specified conditions. All kinds of wax products require paraffin wax to have good temperature resistance, that is, it will not melt or soften and deform at a specific temperature. Commercial paraffins are required to have a range of different melting points according to the conditions of use, the regions and seasons used, and the environment of use.

The main factor affecting the melting point of paraffin wax is the weight of the selected raw material fraction, and the melting point of the paraffin wax removed from the heavier fraction is higher. In addition, the oil content also has a great influence on the melting point of paraffin wax. The more oil in the paraffin wax, the lower the melting point.

oil content
Oil content refers to the amount of low-melting hydrocarbons contained in paraffin wax. Excessive oil content will affect the color and storage stability of paraffin wax, and also reduce its hardness. Therefore, the oil-containing wax paste removed from the vacuum fraction needs to be deoiled by sweating or solvent method to reduce its oil content. However, most paraffin products need to contain a small amount of oil, which is beneficial to improve the gloss and mold release properties of the products.

stability
In the process of modeling or coating, paraffin wax products are in a hot melt state for a long time and come into contact with the air. If the stability is not good, it is easy to oxidize and deteriorate, the color becomes darker, and even gives off odor. In addition, paraffin wax will turn yellow when exposed to light. Therefore, paraffin wax is required to have good thermal stability, oxidation stability and light stability.

The main factor affecting the stability of paraffin wax is the trace amount of non-hydrocarbon compounds and condensed aromatic hydrocarbons it contains. In order to improve the stability of paraffin, it is necessary to carry out deep refining of paraffin to remove these impurities.

thermophysical properties
Paraffin wax has high latent heat of phase transition, almost no supercooling phenomenon, low vapor pressure during melting, chemical reaction is not easy to occur, and chemical stability is good, the phase transition temperature and phase transition latent heat change are small after multiple endotherms, self-nucleation , No phase separation and corrosion.

chemical properties
Paraffin is a mixture of solid higher alkanes, which do not react with common chemical reagents, but can burn. Catalytic cracking reactions can occur industrially.

The chemical activity of paraffin is low, it is neutral, and its chemical properties are stable, and it does not interact with acids except nitric acid and alkaline solutions under normal conditions.

Paraffin classification
According to the degree of processing and refining, it can be divided into three types: fully refined paraffin, semi-refined paraffin and crude paraffin. Each type of wax is divided into different varieties according to the melting point, generally every 2 ℃, such as 52, 54, 56, 58 and other brands. Crude paraffin has a high oil content and is mainly used in the manufacture of matches, fiberboard, and canvas.

Microcrystalline Paraffin
Microcrystalline paraffin is mainly composed of chain hydrocarbons, naphthenic hydrocarbons and some linear hydrocarbons, and the molecular weight range is about 500-1000. paraffin wax manufacturer in malaysia, This is a relatively fine crystal, soluble in non-polar solvents and insoluble in polar solvents.

liquid paraffin
There are many types of liquid paraffin, and their lubricating effects are also different. In the extrusion process, the initial lubrication effect is good, and the thermal stability is also good. However, due to poor compatibility, the product tends to become sticky when the dosage is too large.

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

semi-refined paraffin
It is a granular white solid whose relative density increases with the rise of melting point. The product has good chemical stability, moderate oil content, good moisture-proof and insulating properties, and good plasticity. Candles produced from semi-refined paraffin have a concentrated flame, no smoke, and no tears. For candles, crayons, wax paper, general telecommunications equipment and short circuit and light industry, chemical raw materials, etc.

Chlorinated Paraffin
Chlorinated paraffin is golden yellow or amber viscous liquid, non-flammable, non-explosive and extremely volatile. Soluble in most organic solvents, insoluble in water and ethanol. When heated to above 120℃, it slowly decomposes by itself, and can release hydrogen chloride gas, and the oxides of iron, zinc and other metals will promote its decomposition. Chlorinated paraffin is an auxiliary plasticizer for polyvinyl chloride. Low volatility, non-flammable, odorless, non-toxic. This product replaces a part of the main plasticizer, which can reduce the cost of the product and reduce the flammability. Mainly used for PVC cable material and water pipe, floor material, film, artificial leather, etc.

The main purpose
Because of its high oil content, crude paraffin is mainly used in the manufacture of matches, fiberboards, tarpaulins, etc. After adding polyolefin additives to paraffin, its melting point is increased, adhesion and flexibility are increased, and it is widely used in moisture-proof and waterproof packaging paper, cardboard, surface coating of certain textiles and candle production.

After immersing paper in paraffin, various wax papers with good waterproof performance can be prepared, which can be used in food, medicine and other packaging, metal rust prevention and printing industry; when paraffin is added to cotton yarn, it can make textiles soft, smooth and elastic. ; Paraffin can also be made into detergents, emulsifiers, dispersants, plasticizers, greases, etc.

Fully refined paraffin wax and semi-refined paraffin wax are widely used. They are mainly used as components and packaging materials for food, oral medicines and certain commodities (such as wax paper, crayons, candles, carbon paper), coating materials for baking containers, and for fruit preservation. , Electrical components insulation, improve rubber aging resistance and increase flexibility. It can also be used for oxidation to generate synthetic fatty acids.

As a latent heat energy storage material, paraffin has the advantages of large latent heat of phase transition, small volume change during solid-liquid phase transition, good thermal stability, no supercooling phenomenon, and low price. In addition, the development of aviation, aerospace, microelectronics and optoelectronic technologies often requires that a large amount of heat dissipation generated by high-power components can only be dissipated in a limited heat dissipation area and in a very short time, while phase change materials with low melting points are relatively high. Melting point phase change materials can quickly reach the melting point, make full use of latent heat to achieve temperature control, and have a relatively short thermal response time.

GB 2760-96 stipulates that it is allowed to be used in gum base agent, with a limit of 50.0g/kg. It is also used for anti-sticking in the production of glutinous rice paper abroad, and the dosage is 6g/kg. In addition, it is also widely used in moisture-proof, anti-stick and oil-proof of food packaging materials. It is suitable for components such as food chewing gum, bubble gum, and pharmaceutical gold oil, as well as waxes that directly contact food and medicine, such as heat carrier, mold release, tableting, polishing, etc. method).

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