Rosin can be divided into three types according to its source: resin rosin, wood rosin and floating rosin. Resin rosin, also known as rosin incense, has light color, high acid value and high softening point; Wood rosin, also known as extracted rosin, is inferior to resin rosin in quality, dark in color, low in acid value and easy to crystallize from some solvents; Oil-slick rosin is also called oil-slick rosin. Rosin is a transparent and fragile solid natural resin and a complex mixture, which consists of resin acids (rosin acid, pimaric acid), a small amount of fatty acids, rosin anhydride and neutrals. The main component of rosin is resin acid, accounting for about 90%. The molecular formula is C 19H29 COOH and the molecular weight is 302.46. Resin acid is the most representative rosin acid, which belongs to unsaturated acid, contains * * * yoke double bond, strongly absorbs ultraviolet light, and can be oxidized automatically or induced after being oxidized in air. The appearance of rosin is light yellow to light brown, with glass luster and turpentine smell, and the density is 1.060~ 1.085g/cm3. Melting point 1 10 ~ 1 35℃, softening point (ring and ball method) 72 ~ 76℃, and boiling point about 300℃(0.67kPa). Glass transition temperature Tg-30 ~ 38℃. The refractive index is 1.5453. Flash point (open cup) 2 16℃. The ignition point is about 480~500℃. It oxidizes easily in the air and becomes darker in color.

Soluble in ethanol, ether, acetone, toluene, carbon disulfide, dichloroethane, turpentine, petroleum ether, gasoline, oil and alkaline solution. The solubility in gasoline decreases. Insoluble in cold water, slightly soluble in hot water. Rosin has excellent properties such as tackifying, emulsifying, softening, moisture-proof, anticorrosion and insulation. But its disadvantage is that it is easy to crystallize in solvent. The crystallinity of rosin is due to the different solubility of isomers in some solvents and the different moisture in rosin. Water content of rosin

The quality of rosin depends on color, acid value, softening point and transparency. Generally the lighter the color, the better the quality; The more rosin acid content, the greater the acid value and the higher the softening point.

The viscosity of rosin is very good, especially the pressure sensitivity, fast viscosity and low temperature viscosity, but the cohesion is poor. Because rosin contains double bonds and carboxyl groups and has strong reactivity, it is unstable to light, heat and oxygen, showing poor aging resistance and weather resistance, and is easy to powder and change color. The mixture of rosin fine dust and air is explosive. Rosin is divided into six grades: special, first, second, third, fourth and fifth.

4 quality index editing

Indicator name: Level 1, Level 2, Level 3, Level 4 and Level 5.

A hard and brittle solid with a transparent appearance.

Colors are light yellow, light yellow, dark yellow, brown, yellow and red.

Meet the requirements of rosin-grade glass standard color block.

Softening point (ring and ball method) /℃≥ 76 76 75 75 74 74

Acid value/(mg KOH/g) ≥166166165165164.

Unsaponifiable matter content /%≤ 5 5 5 6 7 7

Ethanol insoluble matter/%≤ 0.030.030.030.030.030.040.04

Ash /%≤0.02 0.02 0.03 0.03 0.04 0.04

Foreign brands include Foral AX (USA), Solros (USA), Rosin oilARO (UK) and Germany.

5 application editing

Rosin is often used as tackifying resin in hot melt, pressure-sensitive and solvent-based adhesives to increase initial viscosity and improve adhesive strength. Rosin can also improve the dryness and peel strength of waterborne acrylate laminating adhesive, and the optimum dosage is 6% of the total monomer. Rosin is a weakly acidic substance. If the amount of SBS all-purpose adhesive or spraying adhesive is too large, it will cause corrosion of iron packaging, and the adhesive solution will soon turn brown-black. Although it does not affect the bonding performance, the appearance is doubtful.

Rosin is very sensitive to the action of light, heat and oxygen, especially in powder form, which is easy to be oxidized, so it should be stored as a whole to prevent oxidation from darkening the color and changing its properties. When the surface of bulk rosin is oxidized, an oxide film is formed, which can prevent the internal rosin from further oxidation. Humidity can accelerate the oxidation process of rosin, and acetic acid will be released during deep oxidation.

6 source code processing editor

gum rosin

Rosin collected in the form of cutting and processing is called rosin. It is characterized by continuous felling of pine trees, which is beneficial to resources.

resin

Make full use of it. China is rich in rosin resources, which is the country with the largest rosin output. The output of rosin will remain above 350,000 tons for a long time. Therefore, it is predicted that the annual output of resin rosin in the world will remain at 650,000-700,000 tons in the next 20-30 years.

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