Basic properties of polyethylene glycol

Polyethylene glycol (PEG), also known as polyethylene glycol ether, English name: Polyethylene Glycol CAS No. 25322-68-3, whose chemical structure formula is HO (CH2CH2O) nH, is prepared by the gradual addition reaction of ethylene oxide with water or ethylene glycol as raw materials, and its raw materials are mainly derived from petroleum products.

The relative molecular weight of 200-600 is a liquid at room temperature, and the relative molecular weight of 600 or more gradually becomes a semi-solid. With the increase of molecular weight, the change from colorless and odorless viscous liquid to waxy solid decreases its hygroscopic ability. It has the chemical properties of alcohol and can be esterified to form esters with fatty acids. Soluble in water, ethanol and many organic solvents. Stable to heat, acid and alkali, and does not work with many chemicals. It has good hygroscopicity, adhesion and lubricity. Non-toxic, non-irritating. Harmless to humans and animals.

Polyethylene glycol (PEG) has a strong water absorption, can absorb water from the air under normal temperature conditions, liquid can be miscible with water in any proportion, when the temperature rises, any grade of solid polyethylene glycol can be miscible with water in any proportion, when the temperature is high to the boiling point of water is, the polymer will precipitate out, precipitation temperature depends on the molecular weight and concentration of the polymer. Polyethylene glycol (PEG) is a non-ionic polymer that is stable under normal conditions, can oxidize oxygen in the air at 120 ° C or higher temperatures, protected by inert gases such as carbon dioxide or nitrogen, does not change at 200~240 ° C, when it rises to about 300 ° C, the molecular chain is broken and degraded.

According to the degree of polymerization of polyethylene glycol, its application can be basically summarized as:

(1), polyethylene glycol series products can be used for pharmaceutical. Polyethylene glycol with low relative molecular weight can be used as a solvent, cosolvent, dispersant, o/w emulsifier and stabilizer for the production of cement suspension, emulsion, injection, etc., and also used as a water-soluble ointment base and suppository base. Solid waxy polyethylene glycol with high relative molecular weight is often used to increase the viscosity and solid formation of low molecular weight liquid PEG, as well as other drugs. For drugs that are not easily dissolved in water, this product can be used as the carrier of solid dispersant to achieve the purpose of solid dispersion. PEG4000 and PEG6000 are good coating materials, hydrophilic polishing materials, film and capsule materials, plasticizers, lubricants and dropping pill substrates, used for the preparation of tablets, pills, capsules, microcapsules and so on.

(2) PEG4000 and PEG6000 are used as excipients in the pharmaceutical industry for the preparation of suppositories and poultices; Used as finishing agent in the paper industry to increase the gloss and smoothness of paper; As an additive in the rubber industry, it increases the lubricity and plasticity of rubber products, reduces the power consumption during processing, and extends the service life of rubber products.

(3) Polyethylene glycol series products can be used as raw materials for ester surfactant.

(4) PEG-200 can be used as a medium for organic synthesis and a heat carrier with higher requirements, and is used as a moisturizer, inorganic salt solutizer, viscosity regulator in the daily chemical industry; Used as softening agent and antistatic agent in textile industry; Used as a wetting agent in the paper and pesticide industries.

(5) PEG-400, PEG-600 and PEG-800 are used as substrates for medicine and cosmetics, lubricants and wetting agents for rubber industry and textile industry. PEG-600 added to electrolyte in metal industry can enhance the grinding effect and enhance the luster of metal surface.

(6) PEG-1000 and PEG-1500 are used as substrates or lubricants and softeners in the pharmaceutical, textile and cosmetic industries; It is used as a dispersant in the coating industry to improve the water dispersion and flexibility of the resin, and the dosage is 10-30%; The ink can improve the solubility of the dye, reduce its volatility, especially suitable for wax paper and printing table ink, but also can be used in the ballpoint pen ink to adjust the ink viscosity; It is used as a dispersant in rubber industry to promote vulcanization and as a dispersant for carbon black fillers.

(7), PEG-2000, PEG-3000 used as metal processing casting agent, metal drawing, stamping or forming lubricants and cutting fluids, grinding cooling lubrication polishing agent, welding agent, etc.; Used in the paper industry as a lubricant, etc., but also as a hot melt adhesive to increase rapid rewetting capacity.

(8) PEG-4000 and PEG-6000 are used as substrates in pharmaceutical and cosmetic industrial production to adjust viscosity and melting point; It is used as lubricant and coolant in rubber and metal processing industry, and as dispersant and emulsifier in pesticide and pigment industry production. It is used as antistatic agent and lubricant in textile industry.

(9) PEG8000 is used as a matrix in the production of medicine and cosmetics industry, which plays the role of adjusting viscosity and melting point; It is used as lubricant and coolant in rubber and metal processing industry, and as dispersant and emulsifier in pesticide and pigment industry production. It is used as antistatic agent and lubricant in textile industry.

Polyethylene glycol can be divided into several series such as pharmaceutical grade, cosmetic grade, food grade and industrial grade according to the purity difference, and this also indicates the usual application areas of polyethylene glycol. Usage: Polyethylene glycol is widely used in the production of food, pharmaceutical, feed, personal care products, chemical and other industries. It is used as a substrate in the production of medicine and cosmetics industry, plays the role of adjusting viscosity and melting point, and is used for pharmaceutical pastes and drugs. Used as lubricant and coolant in rubber and metal processing industry to enhance grinding effect and enhance the luster of metal surface; Used as dispersant and emulsifier in pesticide and pigment industry production; Used as antistatic agent and lubricant in textile industry; It is used as a wetting agent in the paper and pesticide industries. In the daily chemical industry, it is used as a moisturizing agent, inorganic salt solutizer, viscosity regulator, etc.

Medical aspect

PEG is a commonly used pharmaceutical excipient, PEG entries are recorded in pharmacopoeia of all countries in the world. For a long time, PEG has been widely used in soft (emulsion) poultices, suppositories, dropping pills, hard capsules, eye drops, injections, tablets and other pharmaceutical products. Since the 1990s, more and more researches have been conducted on the application of PEG in new pharmaceutical preparations.

Polyethylene glycol is water soluble and has excellent solubility for many drugs. As an amphiphilic polymer, PEG is soluble in both water and most organic solvents, and has the characteristics of good biocompatibility, non-toxic, low immunogenicity, can be excreted through the kidney, and will not accumulate in the body. In addition, PEG has a certain chemical inertia, but it is easy to bond with proteins and other substances after the activation of the hydroxyl group. After bonding, PEG can give many of its excellent properties to the modified substance.

As a surface modification material, the advantages of polyethylene glycol in the systemic circulation can also prevent the deposition of platelets on the surface of the material when in contact with blood, effectively prolong the half-life of the trimmed jewelry in the body, and improve the drug delivery effect. The addition of an appropriate amount of macromolecule PEG in the formulation of solid pharmaceutical preparations such as tablets can increase the fluidity of the drug and improve the gastric solubility of the main drug, which ultimately helps to increase the bioavailability. Therefore, PEG has been increasingly used in the pharmaceutical industry in recent years.

Due to the plasticity of PEG during the production process and its ability to improve the release of drugs from the tablet, high molecular weight PEG (PEG4000, PEG6000, PEG8000) is very useful as a binder for the manufacture of tablets. PEG makes the surface of the tablet shiny and smooth, while not easily damaged.

In addition, a small amount of high molecular weight PEG (PEG4000, PEG6000, PEG8000) can prevent the adhesion between the icing tablets and the bonding between the bottle.

Daily cosmetics

Polyethylene glycol has a capacitating effect, suitable for the manufacture of various high-quality cosmetics, polyethylene glycol stearic acid synthetic polyethylene glycol distearate series products, widely used in daily chemical industry.

In the cosmetics industry, polyethylene glycol can be used in oil-free makeup, shampoo and hair finishing agent, sunscreen, foot odor remover, skin care, anti-corrosion ointment, shaving cream, acne cream, medicinal skin lotion, face wash agent, face wash and soap, hand lotion, lip balm, etc. In the formulation of cosmetics, the addition of polyethylene glycol can improve the ability of skin to absorb additives.

Polyethylene glycol (4000~8000) as a neutral component in the cosmetic formula, has excellent water solubility, non-volatile, non-greasy, can obtain light color products. The consistency of PEG(polyethylene glycol) increases with the increase of relative molecular mass, and suitable products can be deployed according to different requirements, and polyethylene glycol is added to cream, bath liquid, and hand cream, which has the properties of lubricating the skin and not sticking.

Skin cream with polyethylene glycol and luffa has the dual function of curative effect and beauty. Adding polyethylene glycol to all cosmetic formulas has the advantages of good stability and no destruction of organic microbial nutrients.

Polyethylene glycol can also be used as a non-volatile carrier of flavor enhancers, neutral fixation agent of flavor, evaporation blocker of nail polish remover, solvent enhancer in cosmetic formulations.

PEG is used in toothpaste formulations to adjust consistency and extend shelf life. In addition, PEG can also be used as shampoos, shaving agents and hair removal agents consistency adjustment, non-grease lubricants and anti-static shaving agents, bathroom cleaning agents, denture cleaning agents, etc. Polyethylene glycol can also be used to make soap emulsifying additives and plasticizers, so that it retains the aroma of soap, clumps and does not dry and crack, surface and flat, and can improve foaming.

Textile industry

In the textile industry, polyethylene glycol can be used as a spinning aid, a sizing component, a solvent and a dispersant for dyeing operations. Solid powder polyethylene glycol has good film forming properties, lubrication and plasticity, used to treat fiber additives, can make fabrics soft, plasticized and refined, can inhibit the accumulation of static electricity.

Polyethylene glycol reacts with isocyanate to produce linear polymer, which is used as fabric finishing agent to make the fabric smooth, soft, elastic, feel full, and enhance the tear strength, wear resistance, antistatic and antifouling ability. Polyethylene glycol is especially widely used in the textile industry. It is mainly used as detergent, softener, lubricant, anti-depressant, dispersant, dye carrier, air conditioner and finishing agent.

Coatings and ink industry

PEG can be used as substrate instead of water emulsified coating. Low molecular weight PEG has better dispersibility, while high molecular weight PEG can produce better film formation. In any case, the PEG-based coating is more water-resistant than the water-based coating, and can improve the gloss of the film and reduce the odor.

PEG and PEG ester can be widely used as dispersing agents in common PVA emulsion coatings, and high molecular weight PEG is used as evaporation blocking agent in paint stripping agents. Because of its good solubility and lubricity, PEG is widely used in oil. In addition, PEG can also be used in wax paper, printing mud and garden pen inks.

Rubber and cork products

PEG has a strong binding force with rubber without degrading the rubber, coupled with PEG's low volatility and high flash point properties, PEG has been widely used in the rubber industry.

Main applications include:

(1) Used as rubber and polyurethane products release agent, loosening agent. For example: for soles, heels and cooling hoses and other products in the production. When a piece is formed, the PEG can quickly separate the stick from the mold.

(2) The latex is pressed on the fiber surface and the latex solidifies the lubricant.

(3) Filling PEG in SBR rubber can prevent rubber inactivation.

(4) In cork and sponge, PEG becomes a good plasticizer and water retention agent due to its low volatility and good water absorption.

Metal working

In the metal processing industry, PEG (PEG-2000, PEG-3000) has replaced some materials and been popularized and applied, and their water solubility makes them show a very important application value in the manufacture of hollow castings.

PEG can be used as a good lubricant in the process of metal working. Their low volatility allows PEG to be used as a melting stripping aid for low temperature solder, and flux i high molecular weight PEG is a good bond.

papermaking

Low molecular weight PEG is a particularly good plasticizer and softener in the manufacture of celluloid strips. For the production of paper with low water content and high lubricity, PEG can also be used to achieve the purpose.

Chemical raw material intermediates

All PEGs are important chemical feedstock intermediates, especially in the manufacture of non-ionic surfactants, such as the production of PEG copolymers and PEG esters.

PEG esters are formed by the reaction of PEG with fatty acids, and they have a wide range of uses. The details include:

(1) food emulsifier;

(2) Emulsifier for oil used in textile industry;

(3) emulsifiers in pesticides, pharmaceuticals and cosmetics;

(4) Dispersants and lubricants for the plastics industry;

(5) Dispersants and lubricants for cleaning agents.

Electroplating industry

Polyethylene glycol has been applied to different degrees in surface treatment processes such as copper plating, galvanizing, tin plating, tin plating, lead plating, tin plating, lead plating, cadmium plating, chemical polishing, aluminum oxidation, etching, corrosion prevention and oil removal.

Drilling fluid

The use of oil-based drilling fluids to drill highly active shale formations can stabilize well walls, but it is difficult to meet the environmental requirements of some countries. Drillers often have to pay high costs to dispose of mud before discharging it, so the drilling industry is turning to water-based drilling fluids and studying efficient additives to inhibit the formation of active shale. It is in this case that polyethylene glycol is applied to the drilling industry as a drilling fluid additive. The use of polyethylene glycol can not only enhance the inhibition of drilling fluid to soil, but also the environment can allow, so it has been widely used in the world.