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TDI paint crosslinking agent
2017-7-23 17:50:24
TDI paint crosslinking agent
In this paper, the research of system increase the dosage of catalyst and prolong the acting time two kinds of catalysts on the impact of TDI crosslinker, including viscosity, storage performance and crosslinking agent on the paint film.
In this paper, the advantages and disadvantages of two methods are studied by means of dissociation method to compare the molecular weight and the influence of TDI crosslinking agent.
At present, polyurethane resin in the market is used in combination with other resins, and usually polyurethane is in the form of cross-linking agent prepolymer. When used, the crosslinking agent (A component) is mixed with the hydroxyl resin (B component), which is interlinked at normal temperature or high temperature.
Polyisocyanate is an important raw material for the manufacture of crosslinking agents. The commonly used isocyanates in the coatings industry are TDI, HDI, MDI and IPDI, etc. The most widely used is toluene diisocyanate (TDI).
Using TDI crosslinker, coating with high gloss, high hardness, water resistance, oil resistance, solvent resistance and acid and alkali resistance and other advantages, but the deficiency in addition to the serious yellow when exposed to light (uv light), aging and loss of gloss, condensation of the rest of the free TDI content can reach 3%, influence people's health.
The national standard for the free TDI content of polyurethane film has been increased from 0.7% to 0.5%, which indicates that the free TDI in cross-linking agent must be reduced to less than 1.1 percent, and further improvement is required for the dissociation requirement. Now to free monomer method can be divided into three kinds, molecular distillation, solvent extraction and chemical catalysis, including the first two to physical method, its advantage is processed crosslinking agent construction, long storage period of relatively low viscosity to facilitate and remove completely free monomer, but the disadvantage is that equipment is expensive, complex operation, long production period and solvent consumption, few domestic industrial applications.
Chinese name: Diethyl toluene diamine(DETDA)Diethyltoluenediamine Uses:
The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.
Chemical catalysis crosslinking agent is usually in response to a certain extent, to join was not involved in the reaction of the free monomer amine agent in 3 get together the response, already achieved the purpose of reducing swim divorced cyanate ester, which is the most widely used method in China.
Chemical catalysis crosslinking agent is usually in response to a certain extent, to join was not involved in the reaction of the free monomer amine agent in 3 get together the response, already achieved the purpose of reducing swim divorced cyanate ester, which is the most widely used method in China.
The free TDI removal effect is related to a number of factors, such as the solvent polarity, temperature, reaction time, and the feeding mode, which will affect the free TDI content of the final product. Effect is also different, different catalyst of organic metal catalytic effect is better than the amine catalysts, but also brings poor storage life is short, chromaticity, and many other ills, industrial production crosslinking agent with amine catalysts.
The free TDI in the cross-linking agent was removed by chemical method, which was added to a certain amount of catalyst in the later stage of condensation polymerization. How to reduce the content of free TDI better, there are two main ways of thinking, one is to reduce the content of free TDI in crosslinking agent by increasing the amount of catalyst. The second is to use a limited amount of catalyst to reduce the free content by prolonging the catalyst. In the following two working ideas, the synthetic crosslinking agent experiment is carried out in detail.
(1) experimental raw materials
Toluene diisocyanate (TDI - 80/20), industrial products, gansu yinguang; Trimethyl-propane (TMP), domestic industrial products; Solvent: ethyl acetate, butyl acetate, xylene and cyclohexanone, domestic industrial products; DMP - 30 catalyst, domestic industrial products; Antioxidant: BHT, 1010, domestic industrial products; Phosphoric acid, domestic industrial products; Hydroxyl resin, garbo.
(2) experimental scheme
To a certain proportion of T - 80, trimethylolpropane and ethyl acetate and butyl acetate mixed solvent to join in the reaction kettle, stir well, up to 65 ℃ + / - 1 ℃ warm after 1 h, after the heat preservation with uniform temperature to 70 ℃ for 10 min time + / - 1 ℃, insulation 1.5 h; Cooled to 60 ℃ ~ 61 ℃ in the catalyst reaction. When NCO reached 8.6 + or 0.2%, the termination agent and residual solvents were added. The advantages and disadvantages of two kinds of catalysts are studied using this scheme.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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