Rosin refers to a non-volatile natural resin obtained from pine rosin through different processing methods. Rosin is an important chemical raw material, widely used in soap, paper, paint, rubber and other industries.
1. The unique fragrance of pine forest.
2. Alias pine paste, pine fat, pine glue.
3. Refers to the substance distilled from rosin. Solid, transparent, insoluble in water, soluble in alcohol, hard and brittle, light yellow or brown. It is an industrial raw material for the manufacture of paint, soap, paper, matches, etc.
4. Rosin is the oil flowing from the pine trunk that melts into water at high temperature and becomes solid after drying (no fixed melting point). Its color is burnt yellow and dark red, and it is an important chemical raw material. It is mainly used as a fluxant in circuit board welding in daily life. For learning ballet, rosin plays an anti-slip role.
According to its source, rosin can be divided into three kinds: fat rosin, wood rosin and oil rosin. Fat rosin also known as relaxation incense, light color, acid value, high softening point; Wood rosin, also known as extract rosin, is inferior to fat rosin in quality, dark color, low acid value, and easy to crystallize from some solvents; Rosin rosin is also known as Tolle rosin. Rosin is a transparent, brittle solid natural resin, which is a complex mixture composed of resin acids (abietic acid, imaric acid), a small amount of fatty acids, rosin anhydride and neutral substances. The main component of rosin is resin acid, accounting for about 90%, the molecular formula is C19H29 COOH, and the molecular weight is 302.46. Resinous acid is the most representative of rosin acids, belonging to unsaturated acids, containing conjugated double bonds, strong absorption of ultraviolet light, in the air can automatically oxidize or induced oxidation. Rosin appearance is light yellow to light brown, glassy luster, with turpentine odor, density 1.060~1.085g/cm3. Melting point 110~1 35ºC, softening point (global method)72~76ºC, boiling point about 300ºC(0.67kPa). Glass transition temperature Tg - 30~38ºC. Refractive index 1.5453. Flash point (open cup)216ºC. The ignition point is about 480~500ºC. Easily oxidized in the air, the color becomes darker.
Soluble in ethanol, ether, acetone, toluene, carbon disulfide, dichloroethane, turpentine, petroleum ether, gasoline, oil and alkali solution. The solubility is reduced in gasoline. Insoluble in cold water, slightly soluble in hot water. Rosin has excellent properties such as viscosity increasing, emulsification, softening, moisture-proof, anti-corrosion, insulation, etc. The deficiency is that it has a large tendency to crystallize in solvents. The crystallinity of rosin is due to the solubility of the isomers of rosin in some solvents and the different water content of rosin. Rosin moisture content <0.15% does not crystallize; >0.15% easy to crystallize; >0.16% severe crystallization. Rosin crystallization is one of the important problems affecting the quality of rosin, which will make the adhesive flocculent or precipitate small particles, and also make the adhesive liquid opaque. The crystallinity of rosin can be tested by the following method: Take lOg rosin l fragments and 10mL acetone and put them in a test tube, plug, dissolve and stand. If the rosin crystallizes within 15min, the rosin is easy to crystallize; If it precipitates after 2h, it indicates that the rosin is not easy to crystallize and can be used with confidence.
The quality of rosin depends on color, acid value, softening point, transparency, etc. The lighter the color, the better the quality; The more the content of rosin acid, the larger the acid value, the higher the softening point.
The viscosity of rosin is very good, especially the pressure sensitivity, fast viscosity and low temperature viscosity are very good, but the cohesion is poor. Because rosin contains double bonds and carboxyl groups, with strong reactivity, it is less stable to light, heat and oxygen, showing poor aging resistance, poor weather resistance, easy to produce powder and discoloration phenomenon, the mixture of very fine rosin dust and air has explosion risk. Rosin is divided into special, one, two, three, four, five a total of 6 levels.
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