RU2164923C2 - Method of preparing isocyanurate-urethane foam plastic - Google Patents

Abstract

FIELD: preparation of rigid isoceanurate-urethane foam plastics, more particularly manufacture of heat-insulating difficulty combustible coatings used in building industry, machine building and shipbuilding, and refrigeration engineering and power engineering. SUBSTANCE: method comprises reacting excessive amount of isocyanate-containing component with hydroxyl-containing mixture which comprises halogenalkyl phosphate, hydroxyl-containing tertiary amine, water and Lewis acid at ratio of 47.33-55.94:3.70-5.68:0.08- 0.13: 0.04-0.08 by weight parts, and forming oligoether during synthesis of foam plastic in amount of 30.00-50.00 wt parts of oligoether per 100,00 weight parts of isocyanate-containing components. EFFECT: higher reaction rate of preparing foam plastic and high fireproofness of foam plastic, and strength and heat resistance thereof are retained. 11 ex, 2 tbl

Description

 The invention relates to a method for producing rigid isocyanuraturethane foams and can be used for the manufacture of heat-insulating refractory coatings produced by the spraying method used in construction, engineering, shipbuilding, refrigeration, energy.

 A known method for producing isocyanuraturethane foam by reacting an excess of polyisocyanate with a hydroxyl-containing mixture in the presence of a blowing agent, a foam stabilizer and a catalyst is a mixture of a carboxylic acid with a tertiary amine, polyoxyalkylene ethylene diamine or polyoxyalkylene diethylene triamine, an alkali metal carboxylate with a 0.5 mol% polyoxyethylene base 5: 0.2-1.0: 0.5-2.0: 1.0: 0.1-1.0, respectively, in an amount of 4.0-8.0 parts by weight per 100 parts by weight polyisocyanate (A.S. N 1818829, class C 08 C 18/22, 1996). The method allows to obtain a foam with high physical, mechanical and fire characteristics. However, the reaction rate is insufficient to use it as a foam for insulation of vertical and ceiling structures (start time is 8-22 s, rise time of the foam is 50-93 s. When the start time is 8 s and the rise time of the foam is 50 s, there is drainage of still liquid foam with vertical and ceiling surfaces, which leads to characteristic defects of the insulation layer: streaks on vertical surfaces and icicles on ceiling surfaces.

 There is also known a method for producing rigid polyurethane foam by reacting a polyisocyanate with a hydroxyl-containing mixture consisting of tall oil oligoester and triethanolamine with a hydroxyl content of 7-17% and a molecular weight of 270-480, trichlorethylphosphate, a blowing agent - chladone, a solution of sodium acetate in ethyleneamine ethylene glycol , surfactant, water (A.S. N 1462765, class C 08 G 18/14, 1986).

 This method allows to obtain foams with high physico-mechanical and heat-resistant characteristics.

 However, the introduction of the composition of the composition of the oligoester based on tall oil with a hydroxyl content of 7 to 17% in an amount of 100 parts by weight per 100 - 600 wt. including polyisocyanate does not allow to obtain foams with stable physical and mechanical characteristics, leads to unstable opposition of isocyanuraturethane foam to an open flame. Tall oil is a by-product of sulphate pulp. Its qualitative and quantitative composition strongly depends on the species of wood used, the place of its growth, the time of harvesting, the method of transportation, and the technological parameters of pulping.

 The low reaction rate during the production of polystyrene foam (start time more than 10 s) does not allow the known method to be used for the manufacture of high-quality heat-insulating coatings on vertical and ceiling surfaces by the cheapest and most productive method - the spraying method. There is a drainage of the liquid mixture from vertical and ceiling surfaces, which leads to characteristic defects of the thermal insulation layer in the form of streaks on vertical surfaces and icicles on ceiling surfaces.

 The technical result of the invention is to increase the reaction rate of foam production (decrease in curing time), increase fire resistance while maintaining strength and heat resistance.

 The essence of the invention lies in the fact that the production of a rigid isocyanurate urethane foam is carried out by reacting an excessive amount of an isocyanate-containing component with a hydroxyl-containing mixture in the presence of a blowing agent, a foam stabilizer and a catalyst, using an oligoester as a hydroxyl-containing mixture, which is formed directly during the synthesis of a tertiary hydroxy-halogenated water and Lewis acids in their mass ratio, parts by weight: 47.33 - 55.94: 3.70 - 5.68: 0.08 - 0.13: 0.04 - 0.08, in an amount of 30 - 50 mass parts of oligoester per 100 mass parts of isocyanate-containing component.

 The increase in the reaction rate of the foam production is achieved in two ways: strengthening the catalytic system of the hydroxyl-containing component, the use of an isocyanate-containing component with high reactivity.

 To increase the fire resistance of the foam use: maximum yield in the reaction process of heat-resistant isocyanurate cyclic systems; the introduction of flame retardants - halogenated alkyl phosphate, Lewis acid (coordination unsaturated metal chlorides); the inclusion of halogenated in the composition of the polymer due to the formation of chemical bonds.

 The catalytic system for the trimerization and urethane formation of the hydroxyl-containing component is a solution of an alkali metal carboxylate in hydroxyl-containing tertiary amines.

 Tertiary amines are highly effective catalysts for urethane formation and, to a lesser extent, catalysts for the trimerization of isocyanates; alkali metal carboxylates are catalysts for trimerization. The catalyst obtained by mixing these compounds effectively catalyzes the urethane formation reaction and has an increased catalytic activity of the trimerization reaction.

 By introducing the Lewis acid into the hydroxyl-containing component, the following reactions are catalyzed and inhibited.

 The urethane formation reaction is inhibited by blocking part of the amine catalyst due to the formation of a covalent bond with a lone pair of electrons in nitrogen. This leads to an increase in the time for the passage of the reaction of urethane formation, which is necessary to ensure the possibility of passing the reactions of formation of a hydroxyl-containing mixture. The hydrolysis of a halogenated alkyl phosphate is catalyzed by halogen with the replacement of halogen by a hydroxyl group, by ether bonds to form acid esters, which can subsequently react with an isocyanate, with a hydroxyl-containing tertiary amine, to form polyphosphate bonds. The transesterification reaction is catalyzed with the replacement of a halogen-containing alcohol with a hydroxyl-containing tertiary amine.

 Thus, the use of Lewis acid makes it possible to directly obtain a hydroxyl-containing mixture (oligoester) with a high reactivity to urethane formation from the halogenated alkyl phosphate, hydroxyl-containing tertiary amine and water directly during the synthesis of the foam.

 The method is as follows.

 The hydroxyl-containing component is obtained by mixing 47.33-55.94 wt.h. haloalkyl phosphate, 12.50-16.00 parts by weight a blowing agent, 2.70-3.20 wt. including foam stabilizer, 0.08-0.13 wt.h. water with 0.85-1.05 wt.h. alkali metal carboxylate, 3.70-5.68 parts by weight hydroxyl-containing tertiary amines, 0.04-0.08 wt.h. Lewis acids.

 Trichloroethyl phosphate (tri- (β-chloroethyl) phosphate) is used as the haloalkyl phosphate.

 As a foaming agent, a mixture of chladone 113 (trichloro-trifluoroethane) and chladone 11 (trichlorofluoromethane) is used with a mass ratio of 1: 0 - 0.67.

 As the foam stabilizer use oxyalkylene dimethylhydroxysiloxane block copolymer type KEP-2.

 As the alkali metal carboxylate, potassium acetate and sodium acetate are used.

 As a hydroxyl-containing tertiary amine, a mixture of dimethylethanolamine (dimethyl (β-hydroxyethyl) amine) and triethanolamine (tri (β-hydroxyethyl) amine) is used at a mass ratio of 1: 2.00 - 2.50.

 Chlorides of coordination-unsaturated metals — aluminum chloride, zinc chloride — are used as the Lewis acid.

 The hydroxyl-containing component is prepared in two containers.

Halogen alkyl phosphate, a blowing agent, a foam stabilizer, water are sequentially loaded into the first tank, stirred at 18-22 ^° C for 15-20 minutes, settled for 90-120 minutes, mixed again for 5-10 minutes.

Triethanolamine, dimethylethanolamine is successively loaded into the second container, stirred for 5-10 minutes, heated to 70-90 ^° C, charged with an alkali metal carboxylate, stirred for 25-30 minutes (until the carboxylate is completely dissolved), loaded with Lewis acid, mixed in for 10 - 15 minutes, cooled to 18 - 22 ^o C.

The contents of the first container are combined with the contents of the second container at 18-22 ^° C, stirred for 5-10 minutes. The lifetime of the thus obtained hydroxyl-containing component is not more than 120 minutes.

 As an isocyanate-containing component, 4,4'-diphenylmethanediisocyanate (4,4'-MDI) or an adduct of a mixture of polyisocyanate (PIC) and toluene diisocyanate (TDI 80/20) with a two-functional polyester mol.m. 300 - 500 with their mass ratio of 1: 0,100 - 0,125: 0,026 - 0,045. A polyisocyanate is used with a content of isocyanate groups of 29 - 31%, diphenylmethanediisocyanate of at least 50%.

 Polypropylene glycols Laprol 402, Laprol 502 are used as a two-functional simple polyester.

Polyisocyanate, toluene diisocyanate are sequentially charged into the container, stirred for 5-10 minutes, heated to 23-32 ^° C, with stirring and constant flow, the polyester is charged for 30 minutes, while maintaining the temperature within 28-32 ^° C.

 The resulting adduct has an isocyanate group content in the range of 29 - 32%.

The hydroxyl-containing component (component A) is combined with the isocyanate-containing component (component B) under the following technological conditions: temperature of component A 18 - 22 ^o C, temperature of component B 30 - 32 ^o C, the ratio of components by weight A: B is 1: 1.22 - 1.48.

The process of foam formation is as follows. Quick start (start time 1.8 - 3.0 s), intensive rise of foam to a height of 60 - 70% of the final value, slowdown of rise by 1 - 2 s, again intensive rise within 1 - 2 s, curing of the surface film in within 1 - 3 s. Measurements show that the temperature in the body of the foam reaches 150 - 180 ^o C (depending on the thickness of the layer). By the beginning of the curing of the surface film, the foam in the body has already hardened. Therefore, the criterion for the curing time of the foam is taken to be the start time of curing of the surface film (the end time of gelation). It has been experimentally established that for applying a high-quality thermal insulation layer to vertical and ceiling surfaces, the curing time should be no more than 10 s.

 In the process of foaming, the start time and the cure time are measured.

 The resulting foam is kept for at least 48 hours, then subjected to testing. Fire tests are carried out in accordance with GOST 12.1.044-89 "Fire and explosion safety of substances and materials. Nomenclature of indicators and methods for their determination" at the OTM installation, the exposure time of the samples with a flame of 5 minutes.

 Examples of the method are presented in table 1, table 2 presents the characteristics of the resulting foams. In examples 1 to 6, the composition and properties of the resulting foam according to the claimed method are presented.

For foam samples (example 2), the following fire safety indicators are additionally defined: no smoldering temperature; flash point - 415 ^o C; autoignition temperature - 750 ^o C.

As can be seen from the tables, the claimed method allows to obtain foams with a short curing time of 6.5 - 10.0 s, suitable for the manufacture of high-quality heat-insulating coatings by spraying, including on vertical and ceiling surfaces, which ensures the stability of physico-mechanical and fire-fighting indicators. Foams can be guaranteed to operate at temperatures up to 150 ^o C, provide compressive strength of at least 0.29 MPa, are flame retardant.

 All this allows you to significantly expand the scope of their application in comparison with the prototype.

Claims (1)

 A method of producing isocyanuraturethane foam by reacting an excess of an isocyanate-containing component with a hydroxyl-containing mixture in the presence of a blowing agent, a foam stabilizer and a catalyst, characterized in that an oligoester, which is formed directly during the synthesis of the foam from a halogenated alkyl acid hydrochloride and hydroxy acid, is used as a hydroxyl-containing mixture. with their mass ratio, parts by weight: 47.33 - 55.94: 3.70 - 5.68: 0.08 - 0.13: 0.04 - 0.08, in amount 30 to 50 parts by weight oligoester per 100 wt.h. isocyanate-containing component.

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