The method of producing polyurethane foam

 

(57) Abstract:

Polyurethane foam is produced by interaction of a simple mixture of hydroxyl-containing polyesters with an isocyanate component in the presence of silicon-containing surfactant, followed by foaming and curing in the form. At the same time as the isocyanate component, a mixture of MDI with dietilenglikoluretan in their mass ratio of from 0.4 : 1 to 0.5 : 1, which is initially maintained at 85-95oWith 20-40 min, and then injected into the mixture of polyethers with a silicon-containing surface-active agent in the amount of 90-130 wt.h. on 100 wt.h. respectively. The method is simple, based on the use of low-toxic components. Improve operational properties of the polyurethane foam. table 1.

The invention relates to the technology of production of foams, and in particular to a method for producing rigid polyurethane foam, which can be used as a structural material in special mechanical engineering, instrumentation and other industries.

Known way to obtain a rigid polyurethane foam by reacting a mixture of simple hydroxyl-containing polyesters and nitroacetate foaming agent, surfactants and other components (as USSR N 1181293, MKI 08 G 18/00, publ. bull. N 39, 1990).

The disadvantage of this method is the complexity of the applied composition and process of preparation of the working mixture, and the introduction into the composition as the blowing agent of large quantities (10-40 wt.h.) trichloromethane leads to the fact that in the finished foam high content of elemental chlorine, and, consequently, high corrosiveness.

The closest in technical essence and the achieved result to the present invention is a method of obtaining a rigid polyurethane foam by reacting a simple hydroxyl-containing polyesters and isocyanate component in the presence of a blowing agent trichloromethane, surfactants and other additives, with a simple mixture of hydroxyl-containing polyesters pre-enter bioretention or a mixture of bioretention with a molecular mass of 271-1350 (AU USSR N 1121973, MKI C 08 G 18/ 00, publ. bull. N 39, 1990). Synthesis dienetadie as an intermediate product used in this method is performed by mixing successively introduced into the reactor with a simple polyester servings of low-molecular diisi the P>C for 30-60 minutes. Upon receipt of the polyurethane foam is injected into the reactor components polyol as one mixture (with the exception of a blowing agent) and stirred for additional 30-60 minutes, then introducing a blowing agent and isocyanate component. Subsequent foaming and curing is carried out in the form.

The disadvantages of this method include the following. Synthesis of the intermediate product - dienetadie, and thus web (extended mix) with a polyol as one component of a stretch in time the process of obtaining foam. Introduction to composition as the blowing agent of large quantities (30 wt.h.) trichloromethane leads to the fact that in the finished foam high content of elemental chlorine. And use for the synthesis of bioretention highly toxic substances - low molecular weight isocyanates (diphenylmethanediisocyanate and diisocyanate) require additional measures to ensure the safety of the work.

The problem solved by the authors of the invention is to develop a simple method based on the use of low-toxic components, for the production of rigid polyurethane foam with a regulated content of elemental chlorine is isawanya as a structural material, and resistance to high shock loads.

A new technical result achieved when using the proposed method in comparison with the prototype, is to improve operational properties of the polyurethane foam by reducing corrosion activity and increased resistance to high shock loads, to simplify and reduce the duration and increase the security of the method.

This technical result is achieved by the fact that in the known method of producing polyurethane foam by the interaction of a mixture of polyether with an isocyanate component in the presence of silicon-containing surfactant, followed by foaming and curing in the form, in accordance with the proposed method as an isocyanate component, a mixture of MDI and diethylenglycol, when the mass ratio respectively of from 0.4 :1 to 0.5 : 1, which is initially maintained at a temperature of 85-95oC for 20-40 minutes and then injected into the mixture of polyethers with a silicon-containing surface-active agent in the amount of 90-130 wt.h. on 100 wt.h. respectively.

The presence of the distinctive features of the proposed the training of rigid polyurethane foam was prepared as follows.

Unlike the prototype method the mixture of the starting components are produced by successive separate mixing isocyanate component and a polyether and surfactants and their subsequent communication. Provided the sequence of mixing the above components at the initial stages of chemical interaction leads to the fact that low molecular weight fractions MDI activate the process of interaction between isocyanate and hydroxyl groups, which is accompanied by release of a large amount of heat sufficient for the development of the mobility of molecules diethylenglycol and high molecular weight fractions MDI.

In the method prototype a necessary step in the operation was the preparation of the intermediate product - dienetadie - and his long, thus web with a mixture of polyol as one, as well as the introduction of a blowing agent to provide a low density in the final product and the desired strength. In addition, in the known method a long mixing provides for uniform reciprocal distribution of reagents and to provide a full response in their full amount due to priodically increase the number of effective collisions. Whereas in the proposed method, shorter and with fewer reagents than in the prototype, stirring enough for mutual distribution in the reaction volume of mobile and reactive low molecular weight fractions included in the composition used MDI and completeness of reactions between the major components.

Thus, in the present method ensures completeness of a reaction gas, and polymerization at the initial stages, which is necessary to ensure the required quality of the final product, and simplification of the method by reducing the number of operations and time.

The problem of further improving the quality polyurethane foam to increase its resistance to shock loads, increasing the apparent density in the prototype, as it can be assumed theoretically, can be solved by reducing the content of the foaming agent.

However, achieving densities in the finished products of the order of from 600 to 800 kg/m3compounded in accordance with a known method, because in this case it is necessary to decrease foaming agent below under debate in the form, the presence of a blowing agent in the envisaged limits can result in significant residual stresses in the material and, consequently, to the loss of health and destruction of the structure.

With this in mind, we can conclude that the prototype has limited technological capabilities in terms of constructing a workable products with high toughness and a high apparent density, in Addition, the use in the prototype, the foaming agent - trichloromethane - causes a high content of elemental chlorine, and, as a consequence, highly corrosive polyurethane foam.

In the proposed method, the reproduction in the finished product of the apparent density of 600-800 kg/m3provided through the foaming composition of carbon dioxide emitted in sufficient quantities in chemical reactions used in the method of the components in the claimed proportions, which eliminates the use of traditional foaming agent. This allows you to lower the content of elemental chlorine, which is recorded in the form of a gas phase in the cell material, and, consequently, lower corrosion the x compositions. The optimal value of the composition meets the composition containing per 100 wt.h. mixtures of polyethers and silicon-containing surfactants from 90 to 130 wt.h. a mixture of MDI and diethylenglycol taken in a weight ratio of from 0.4:1 to 0.5:1. This composition produces a foam with a density impact strength not less than 7.2 kJ/m2and the chlorine content is not greater than 0.07%, which significantly lower the chlorine content of the material obtained by the method prototype (approximately 30 times).

The choice of temperature range endurance isocyanate mixture components at temperatures due to the experimental condition for the optimal viscosity of the composition at this stage contact the specified components of the mixture and uniform mixing and the maximum possible mutual distribution. The implementation of these conditions leads to the reproduction of the polyurethane foam of the required quality.

The use of the claimed sequence of mixing of the reagents eliminates toxic components, due to which security method is higher than that of the prototype.

In the analysis of compliance with the criterion of "izobretatel alnost the introduction of components to reduce the content of chlorine while maintaining the material requirements for specific indicator toughness and density.

Thus, the proposed method provides receiving the rigid polyurethane foam with a chlorine content of not greater than 0.07%, and the specific impact strength is not below 7.2 kJ/m2that gives the possibility to use it as a structural material in special areas of technology where there are increased requirements to the content of elemental chlorine, safety, with less duration and number of operations than in the prototype.

The possibility of implementation of the technical solutions of the following examples of its implementation.

Example 1.

Pre-prepare a mixture of MDI and diethylenglycol in the following ratio of components (wt.h.):

The polyisocyanate - 0,4

Diethylenglycol - 1,0

In a portion of diethylenglycol enter a portion of the MDI and the mixture was incubated in a glycerin bath at a temperature of 85 - 95oC for 20-40 minutes.

Then prepare a mixture of polyethers, which are used Laprol B and Lupranol 294 and a surfactant, which is used as silicone foam controller cap 2, with the following ratio of components (wt is Electromechanica at a temperature of 22oC for 2 minutes. After mixing the mixture is cooled to a temperature of 22oC.

To a mixture of MDI and diethylenglycol add a mixture of polyethers and surfactants, with 100 wt.h. mixtures of polyethers and surfactants charge 100 wt.h. a mixture of MDI and diethylenglycol. The composition is stirred at Electromechanica for 40 seconds. Immediately after mixing, the composition is poured for foaming and curing in a restrictive form.

Terms of method and quality of the foam obtained in example 1, are shown in table.

Example 2 - 10.

Data on the conditions of implementation of the method in examples 2-10, as well as indicators of the quality of the obtained foam are summarized in table.

As follows from the table, the inventive method produces a foam with the content of elemental chlorine not more than 0.07% and the specific impact strength not less than 7.2 kJ/m2that corresponds to the desired quality of finished products in terms of high resistance to shock and evidenced by a decrease in the content of elemental chlorine in izgotovlena material 30 RIRs with the isocyanate component in the presence of silicon-containing surfactant, followed by foaming and curing in the form, characterized in that, as the isocyanate component, a mixture of MDI with dietilenglikoluretan in their mass ratio of from 0.4 : 1 to 0.5 : 1, which was first incubated at 85 - 95oC for 20 - 40 min, and then injected into the mixture of polyethers with a silicon-containing surface-active agent in the amount of 90 - 130 wt. hours At 100 wt. 'clock respectively.

 

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