Метилен ди-p-фенил диизоцианат

Описание

4,4'-Diphenylmethane-diisocyanate (MDI) is used in the manufacture of various polyurethane products - elastic and rigid foams, paints, lacquers, adhesives, binding agents, synthetics rubbers, and elastomeric fibers.

Химические свойства

white to light yellow flakes or crystals

Использование

Diphenyl methane diisocyanate (MDI) is widely used in polyurethane coatings, this product is made of polyurethane foam used as a warm (cold), building materials, vehicle, ship parts; masterwork can made car Block, buffer, synthetic leather, non plastic polyurethane, polyurethane elastic fiber, no plastic elastic fibers, films, adhesives.

Определение

ChEBI: A diisocyanate consisting of diphenylmethane with two isocyanate groups at the 4- and 4'-positions.

Подготовка

Phosgene (800 g, 8 mol) (for a safe source) was dissolved in o-dichlorobenzene (2000 mL), and the resulting solution was cooled in an ice-salt bath. To the stirred solution, a hot solution of 4,4'-diaminodiphenylmethane (200 g, 1.01 mol) in o-dichlorobenzene (1000 mL) was slowly added through a heated dropping funnel. The rate of addition was regulated so that the temperature of the phosgene solution did not rise substantially above 0°C. The fine suspension that resulted was slowly heated and additional phosgene (700 g, 7.1 mol) was added at 130 °C until a clear solution appeared. After purging with carbon dioxide, the solvent was removed in vacuo and the product was purified by vacuum distillation. At 156–158 °C (0.1 mmHg), 215 g (0.85 mol, 84%) of 4,4’-diphenylmethane diisocyanate was obtained. Several procedures for the preparation of isocyanates with phosgene have been described. Nevertheless, many of them require the delivery of gaseous phosgene from an external source, such as a pressurized cylinder.

Общее описание

Diphenylmethane-4,4-diisocyanate is a light yellow colored solid. 4,4'-Diphenylmethane diisocyanate is not soluble in water. 4,4'-Diphenylmethane diisocyanate may be toxic by ingestion, inhalation, or skin absorption. If in a solution 4,4'-Diphenylmethane diisocyanate may or may not burn depending on the nature of the material and/or the solvent. It's used to make plastics.

Реакции воздуха и воды

4,4'-Diphenylmethane diisocyanate is not soluble in water.

Профиль реактивности

Isocyanates and thioisocyanates, such as 4,4'-Diphenylmethane diisocyanate, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence, [Wischmeyer(1969)].

Угроза здоровью

Breathlessness, chest discomfort, and reduced pulmonary function.

Пожароопасность

Noncombustible; flash point (open cup) 202°C (395°F). MDI reactions with strong oxidizers, acids, and bases can be vigorous.

Контактные аллергены

MDI is used in the manufacture of various polyurethane products: elastic and rigid foams, paints, lacquers, adhesives, binding agents, synthetic rubbers, and elastomeric fibers.

Профиль безопасности

Poison by inhalation. Mildly toxic by ingestion. Human systemic effects by inhalation: increased immune response and body temperature. A skin and eye irritant. An allergic sensitizer. Questionable carcinogen. Mutation data reported. A flammable liquid. When heated to decomposition it emits toxic fumes of NOx and SOx.

Возможный контакт

MDI is used in the production of polyurethane foams and plastics; polyurethane coatings; elastomers, and thermoplastic resins.

Экологическая судьба

Due to its low vapor pressure (0.000 62 Pa at 20 ℃), MDI partitioning to the atmosphere is limited; and vapors are rapidly eliminated by reaction with hydroxyl radicals (22 h half-life). Degradation by either direct photolysis or hydrolysis by water vapor to methylenedianiline (MDA) does not play a significant role in the atmospheric fate of MDI. In water, the isocyanate group of MDI can be rapidly hydrolyzed to an amine (<1 min half-life) that in turn reacts at a much faster rate with another isocyanate group to yield urea. Because MDI has two isocyanate groups, these reactions lead to cross-linked polyureas, which are inert, insoluble solids. Unless MDI is well dispersed in water, these processes result in the formation of a solid polyurea crust that encases the unreacted material, restricts both water ingress and amine egress, and leads to higher yields of polyurea. Under stirred aqueous conditions, the fraction of 4,4'-MDI converted to 4,4'-MDA is less than 1%; unstirred, the fraction is 0.005%. MDI released to soil will not exhibit significant transport to other environmental media due to the favored reaction with water to form inert polyureas and binding to the soil biomass. As expected, pMDI and the waterinsoluble oligo- and polyureas that form when pMDI enters an aqueous environment showed no biodegradation over 28 days in a guideline study.

Перевозки

UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required

Несовместимости

May form explosive mixture with air. Isocyanates are highly flammable and reactive with many compounds, even with themselves. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Reaction with moist air, water or alcohols may form amines and insoluble polyureas and react exothermically, releasing toxic, corrosive or flammable gases, including carbon dioxide; and, at the same time, may generate a violent release of heat increasing the concentration of fumes in the air. Incompatible with amines, aldehydes, alkali metals, ammonia, carboxylic acids, caprolactum, alkaline materials, glycols, ketones, mercaptans, hydrides, organotin catalysts, phenols, strong acids, strong bases, strong reducing agents such as hydrides, urethanes, ureas. Elevated temperatures or contact with acids, bases, tertiary amines, and acylchlorides may cause explosive polymerization. Attacks some plastics, rubber and coatings. May accumulate static electrical charges, and may cause ignition of its vapors. Unstable above 100F/38C. Polymerizes at temperatures above 204C. Contact with metals may evolve flammable hydrogen gas.

Утилизация отходов

Controlled incineration (oxides of nitrogen are removed from the effluent gas by scrubbers and/or thermal devices).