What is alkyd resin, what is drying oil, and what is the purpose of drying modification?

What is alkyd resin, what is drying oil, and what is the purpose of drying modification?

1. drying oil

refers to oils composed of fatty acids with two, three or more double bonds (such as linoleic acid, linolenic acid, tung oleic acid, etc.), such as perilla oil (yinan oil), linseed oil, tung oil, Catalpa oil, hemp oil (linseed oil), dehydrated castor oil, etc., generally yellow liquid, iodine value above 130, the main components are glycerol esters of unsaturated fatty acids such as linolenic acid and linoleic acid. In the air can absorb oxygen and dry consolidation into a continuous uniform, elastic dry film. It is an important raw material for the manufacture of ink, paint, oil paint, sealant, rust inhibitor, release agent, lubricant, soap and other fine chemical products. Some are edible, some are not.

After adding drying agent and other synergistic film-forming substances (synthetic resin such as aldehyde ketone tree, aldehyde resin, maleic acid modified rosin resin, solid acrylic resin, rosin modified phenolic resin, petroleum resin or natural resin such as damma resin, rosin, etc.), it can be widely used in paint, ink, antirust agent, sealant, waterproof ointment, linoleum, linoleum and other industries after processing at appropriate temperature.

The drying performance of the grease used in the production of paint is divided according to the ratio of oxygen to oxygen in the air when the grease is coated on the surface of the object, and gradually changes from liquid to solid and dries into a film. The fast drying is called drying oil, the slower is called semi-drying oil, and the long-term non-drying oil is called non-drying oil. The speed of oil drying is determined by the content of unsaturated fatty acid glycerides in oil. Vegetable oil with high content of unsaturated fatty acid glycerides contains more conjugated double bonds, which is easy to combine with oxygen in the air, the stronger the activation ability, the faster the film is, the better the drying, suitable for the production of paints, coatings, inks, rust inhibitors, etc.

measuring the content of unsaturated fatty acids in fats and oils, it is usually expressed by the iodine value, and the content of unsaturated fatty acids with high iodine value is also high. The so-called iodine value is the number of grams of iodine that can be absorbed per 100 grams of oil. Because the conjugated double bond structure in the oil is easy to react with iodine, the more double bonds, the greater the amount of iodine absorbed, and the faster the drying of the oil. Iodine value above 130, such as tung oil, catalpa oil, linseed oil and other dry oil, iodine value generally between 100 and 130 is semi-dry oil, such as soybean oil, corn oil, persimmon oil, sunflower seed oil and so on. Iodine value below 100 is not drying oil, such as castor oil, coconut oil, peanut oil and so on. Non-drying oils are also used as raw materials for non-drying acid resins in paint production and as plasticizers for nitro fiber paints. Dry oil iodine value above 130 containing unsaturated double bonds of fatty acid glycerides. The base for the manufacture of paint coatings. The drying film of the coating is to rely on the unsaturated double bond of the fatty acid carbon bond automatic oxidation polymerization, so as to become a body structure and curing film, the cured coating film is not softened, rarely dissolved by the solvent. The difference degree of dryness depends on the number and position of double bonds in the structure of unsaturated fatty acids, and the greater the degree of unsaturation, the easier it is to dry. The base material for the manufacture of coatings needs to be heated and polymerized at a temperature of 250-290°C.

paints include natural drying oils and modified drying oils.

2. alkyd resin

English name: alkyd resins.glycerol -phthalic resin, an oil-modified polyester resin made by the condensation polymerization of polyols, phthalic anhydride and fatty acids or oils (fatty acid triglycerides). According to the number and structure of double bonds in fatty acid (or oil) molecules, it can be divided into three types: dry, semi dry and non dry. Dry alkyd resins can be cured in air; non-dry alkyd resins are mixed with amino resins and cured by heating. In addition, according to the content of fatty acid (or oil) or phthalic anhydride, it can be divided into short, medium, long and very long alkyd resins with four oil degrees. After the alkyd resin is cured, it has gloss and toughness, strong adhesion, and has good wear resistance, weather resistance and insulation.

alkyd resin is polycondensation of polyfunctional alcohol, polybasic acid and vegetable oil or vegetable oleic acid, and the number of double bonds in different kinds of vegetable oil or fatty acid molecules is different, which can be divided into dry, non-dry and semi-dry alkyd resin. Dry alkyd resin can be self-drying in the air, and its drying is the process of cross-linking and curing of macromolecules in the air by oxygen. According to the content of vegetable oil or vegetable oleic acid used to divide, there are short oil degree, medium oil degree, long oil degree, ultra-long oil degree and ultra-short oil degree alkyd resin alkyd resin manufacturing methods are melting method and solvent method. The melting method is to use polyol, polyacid, vegetable oil or vegetable oleic acid under the protection of inert gas heating, high temperature esterification, until the acid value meets the requirements, and then add solvent dilution. Solvent method is the reaction of raw materials in the solvent xylene, xylene as a solvent, can produce azeotropic with water, accelerate the reaction rate. Compared with the melting method, the reaction temperature required by the solvent method is lower, the reaction conditions are easy to control, and the color of the synthesized alkyd resin is lighter. The performance of alkyd resin is related to the type of oil. With the size and structure of molecular weight, the performance is also different. It has a wide range of applications in paints, coatings, ships and so on.

3. drying oil alkyd resin

drying oil alkyd resin refers to an alkyd resin mainly modified by unsaturated fatty acid or drying oil or semi-drying oil with iodine value of 125-135 or higher, which can be directly coated into a thin layer. Mainly used for all kinds of self-drying and low temperature drying of alkyd varnish and porcelain products. Can be used to paint large cars, toys, mechanical parts, etc.

1 Features

acid resin, it is an alkyd resin modified with crude oil such as sesame oil, perilla oil, catalpa oil, hemp oil, etc. or semi-high oil such as soybean oil and sunflower oil: the coating film is in the room;} I can be directly converted into a continuous cured film in the presence of oxygen. For the preparation of self-drying or drying coatings. According to the different oil content, the coating film has different elasticity and durability, gloss, oil resistance, adhesion, hardness, wear resistance, water resistance, electrical insulation and so on are better.

dry alkyd resins are self-drying in air by means of oxidative crosslinking. In principle, dry alkyd resins are modified products of drying oils. The drying principle of this paint film is that alkyd resin molecules are crosslinked into macromolecules through a series of reactions. The molecular weight of dry oil is low, and the formation of macromolecules requires multi-step crosslinking, so it takes a long time for the paint film to work hard. By drying oil synthesis of alkyd resin, equivalent to an increase in the molecular weight of the drying oil, only need less crosslinking point can be cured into a film, while the film performance of alkyd resin is significantly better than the drying oil film.

2 Types of drying oil alkyd resin

a. dry short oil alkyd resin

dry short oil alkyd resin containing oil or fatty acid content of 30% to 40%. It is mainly made of linseed oil, some tung oil, soybean oil, castor oil, catalpa oil and other drying oils and fatty acids as the main raw materials. Alkyd resin has high viscosity and must be dissolved by aromatic hydrocarbon solvent. The alkyd resin lacquer is applied by spraying or dipping, preferably without brushing. At room temperature, it can automatically oxidize and dry, with good self-drying performance, general flexibility, good gloss, light and color retention, weather resistance, and fast drying speed. Short oil alkyd resin has high hardness, good gloss and abrasion resistance. It is suitable for metal products such as automobiles and machine parts, and can be used as topcoat and primer. Short oil alkyd resin can be used alone as baking paint, and can also be mixed with amino resin, urea-formaldehyde resin, etc.

B. Dry medium oil alkyd resin

medium-oil alkyd resin contains 40% ~ 60% oil or fatty acid, which is most commonly used in alkyd resin. The paint made of alkyd resin can be sprayed, brushed and coated. The paint film can work quickly, with good gloss and weather resistance. It can be dried by itself or mixed with oxygen-based resin. The drying time is longer than that of short-oil alkyd resin paint, and the light and color retention is slightly worse. Dry medium oil alkyd resin is used as self-drying varnish, primer, etc., can also be used as decorative paint, architectural paint, furniture paint, metal primer, etc., can be constructed on metal, wood and other materials.

c. Long oil alkyd resin

long oil alkyd resin containing oil or fatty acid content in 60% ~ 70%. Dry long oil alkyd resin has good drying performance, good film elasticity, good light and color retention and weather resistance, but the film hardness, wear resistance than the oil alkyd resin is poor. Long oil alkyd resin soluble in aliphatic hydrocarbon solvents, low viscosity, easy to brush construction, good leveling performance, can be used for indoor and outdoor building coatings and marine coatings, can be compatible with oil-based resin paint, can be used to enhance oil-based resin paint and latex paint.

d. Very long oil alkyd resin

very long oil alkyd resin containing oil or fatty acid content of more than 70%, soluble in aliphatic hydrocarbon solvents, compatible with oil-based resin paint. Such alkyd resins are slow to dry, but excellent in brushing and weatherability. Can be used for ink, color base material, outdoor house paint.