Acrylic Resins

Acrylic Resins

Acrylic compounds are the common name of plastics, resins and oils obtained by synthesis. From the acrylic used, depending on the type of compound and the conditions of the process, hard and transparent, soft and flexible solids or sticky, viscous liquid products can be obtained. Acrylic compounds are the raw material of various compounds such as molded building materials, optical instruments, jewelry, adhesives, coating materials and woven fibers. For example, orlon and acrylan are the trade names of acrylic yarns, and plexiglass is the tradename of glass-like acrylic materials.

The main members of the family of polymers known as polyacrylic are acrylic and methacrylic acids. The methyl esters of these acids easily polymerize in the presence of peroxide catalysts.

These are resins with outstanding properties such as color and gloss resistance, alkali and oxidation resistance, hardness, adhesion and bonding strength, and film life, and which have a distinguished place among coating formulas. Generally, they are resins formed as a result of polymerization of acrylic acid derivatives containing esters of acrylic acid, methacrylic acid, acrylonitrile and their copolymers. They are also known as acrylate resins.

Acrylic Acid:

It is an organic acid with the formula CH2=CHCOOH, also called propenoic acid. In industry, it is obtained by the reaction of acetylene and carbon monoxide with water in the presence of a nickel catalyst or by the hydrolysis of acrylonitrile compounds. It is the starting material in the production of polymers.

Acrylic Based Paint:

Water-thinned synthetic paints made with synthetic binders such as polyvinyl acetate or acrylic resins. Other binders added to paint to add specific properties or reduce costs are styrene, epoxy, and polyvinyl acetate. Acrylic is a substance that dries quickly, flows smoothly, can be easily cleaned with water and is easily mixed with paint materials. It gives both the transparent shine of watercolor and the consistency of oil paint. It is more resistant to heat and other damaging effects than oil paint.

Acrylic-Based Paint descriptions are as follows.

(1)Mainly stable dispersion of polymeric substance in aqua medium.

(2) Dispersion of plastic or resin in natural or synthetic water; synthetic, made by emulsion polymerization. (It must be noted that after polymerization, acrylic-based paint is a solid dispersed in water, so it is not an emulsion. Acrylic-based paint and emulsion are similarly used in the paint industry.)

High performance acrylic based paints contain 100% acrylic resin.

100% Acrylic Based Paint: These are paints that use only acrylic resin as a binder and are diluted with water. In general, very high quality acrylic-based paints are used for many different architectural coatings. 100% Acrylic-based paints have super adherence, long-term flexibility, breathability, alkali resistance, hardness, and gloss resistance.
 

Alkyd Resins

They are polymers, the condensation product of oil and fatty acids, polyacids and polyols, which generally yield products that can be used as topcoats.

Since 1927, it has been determined that the alkyds produced with the fatty acids of the drying oils dry in the air and give durable films, and the industrial application has gradually developed and alkyd resins have taken their important place today.

Since oil or fatty acid constitutes an important part of the body in the classification of alkyd resins, the oil percentage is used as a criterion. For example, 35 to 45% can be classified as low oil; 46 to 55% can be classified as moderate oil; 56-70% can be classified as much oil; and over 70% can be classified as too much oil.

Alkyd production processes:

1) Fatty acid method: Fatty acids, polyhydric alcohol and dibasic acid are heated to 210 thru 250°C and kept at this temperature until they reach the desired properties. If the polyhydric alcohol and dibasic acid are heated prior to addition of fatty acid, there will be a drastic increase in viscosity. The molecular weight of the product varies in a very wide range. In addition, after the addition of drier, its stability becomes low and early drying is observed on the surface in the form of a film.

2) Fatty acid method: Fatty acids, oil, polyol and dibasic acid are heated again to 210 thru 250°C and kept at this temperature until the desired properties are reached. Compared to the monoglyceride method, films that dry quickly on the top and slowly on the inside are obtained. There is also the danger of partial gelation during the reaction.

3) Oil dilution method: It is carried out by adding oil at high temperature to the alkyd prepared by one of the other methods. It increases the tendency of the product to be applied with a brush. But, the films are soft and flimsy. The color also deteriorates quickly.

4) Alcohollysis or monoglyceride method: First, partial ethers are prepared with oil, mostly glycerine, and sometimes with another polyol. The remaining hydroxyl groups are then reacted with dibasic acid. The first stage is carried out without a catalyst at around 280°C or with a catalyst at around 230 to 240°C. The completion of the first step is evident when the oil is not dissolved in methanol, but the resulting monoglyceride is dissolved in methanol twice its volume. After that, the temperature is lowered to around 200°C, dibasic acid and sometimes some more polyol are added and the temperature is increased to 230 thru 250°C. The product is kept at these temperatures until it reaches the desired properties.

Factors affecting manufacture:

The factors affecting manufacture includeraw materials, main reactions, order of addition, mixing speed and means, reaction temperature and medium, and catalysts.

The raw materials include mainly polybasic acids, polyhydric alcohols and fatty acids. The most common usedpolybasic or more precisely dibasic acids include phthalic acid isomers from aromatic acids and especially phthalic anhydride.Unsaturated maleic anhydride and fumaric acid are also important. Although aliphatic acids give soft products with glycerin in the ratio of the length of the carbon chain between the carboxyl groups, phthalic acid isomers, in which the molecular acid and carboxyl groups that do not have such a chain, are tightly bound to the benzene ring and are deprived of position change, give hard and brittle resins. The most important monobasic substance of alkyd resins is fatty acids. Almost all of them are obtained from vegetable oils, namely glycerides. The most important fatty acids include stearic, oleic, linol, linolene, oleostearic, ricinol and dehydrated ricinol.

Dryers added to alkyds include oil soluble salts such as Co, Mn, Zn and Pb, etc. They are usually added at a rate of 0.1% to 1%.

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