Low hydroxyl value tung oil polyol and preparation method thereof

Abstract

The invention discloses a low hydroxyl value tung oil polyol preparation method, which comprises: (1) mixing tung oil, carboxylic acid, a catalyst and a hydroxylating reagent according to a certain ratio, heating to a temperature of 35-45 DEG C, adding a hydrogen peroxide solution in a dropwise manner under a vigorous stirring condition, maintaining the reaction temperature at 40-65 DEG C, maintaining the reaction temperature for 3-5 h after completing the adding, carrying out standing layering after completing the reaction, separating to obtain a water phase, neutralizing, carrying out water washing, and carrying out pressure reducing distillation to obtain tung oil polyol; and (2) mixing the tung oil polyol prepared in the step (1) and an alkaline catalyst according to a certain ratio, heating to a temperature of 90-140 DEG C, adding an epoxide, carrying out a polymerization reaction, and after completing the reaction, carrying out acid neutralizing, water washing and pressure reducing distillation to obtain the low hydroxyl value tung oil polyol. According to the present invention, the prepared low hydroxyl value tung oil polyol has the hydroxyl value of 30-100 mgKOH / g, the acid value of less than 1.0 mgKOH / g, the moisture content of less than 0.1 wt% and the yield of more than 90%, and is suitable for the preparation of polyurethane soft foam materials, polyurethane elastomers, and the like.

Description

technical field [0001] The invention belongs to the field of polyurethane materials, and in particular relates to a low-hydroxyl value tung oil polyol and a preparation method thereof. Background technique [0002] Polyurethane materials have been widely used in industry and people's daily life due to their good mechanical properties and easy molding. The main raw materials used to produce polyurethane include isocyanates, polyols and other additives, of which polyols account for more than 50%. In the process of industrial production, polyols are mainly used in the field of polyurethane, so the factors affecting the polyurethane industry are also the main factors affecting the polyol market. Polyols can be divided into polyether polyols and polyester polyols according to their molecular structure. Among them, polyether polyols dominate the market, accounting for more than 70% of the entire polyol demand. [0003] Typically, polyols are prepared from petroleum. As a non-re...

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Problems solved by technology

However, tung oil is used to prepare high-quality vegetable oil polyols. Because tung oil has a high degree of unsaturation and is the only unsaturated vegetable oil with conjugated double bonds in nature, the iodine value reaches more than 170, and more than 85% of the unsaturated bonds are Carbon-carbon conjugated triene bonds, so the presence of conjugated double bonds in tung oil in the process of preparing polyol epoxidation makes the epoxy group highly reactive, poor in selectivity, and prone to side reactions, thereby generating macromolecular cross-links. Co-product, resulting in a sharp increase in viscosity, usually solid at room temperature, cannot be used for further synthesis of polyurethane materials

Research literature (e.g. Epoxidation of Natural Triglycerides with Ethylmethyldioxirane, Journal of the American Oil Chemists' Society, 1996, 73:461-464) examines different vegetable oils such as corn oil, soybean oil, sunflower oil, cottonseed oil, tung oil During the epoxidation process of unsaturated vegetable oils, it was also found that the tung oil with only conjugated double bonds undergoes a crosslinking reaction during the epoxidation process, resulting in a sharp increase in viscosity and cannot be used to prepare polyurethane materials.

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