The method of producing polyurethane foams

IPC classes for russian patent The method of producing polyurethane foams (RU 2010813):

C08J9/30 - by mixing gases into liquid compositions or plastisols, e.g. frothing with air

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(57) Abstract:

Usage: for pipe insulation. The inventive polyol and the polyisocyanate are mixed at a pressure not below the equilibrium, filling the previously one of gas, namely carbon dioxide, argon, sulfur hexafluoride, at a pressure of at least 30 bar, then the reaction mixture through the orifice squeeze in communicated with the atmosphere of the foaming agent and the formed foam is applied on the surface or in the volume. The process of mixing is in the unit-mixer, which is also the gas supply unit. Polyurethane foam has an apparent density 64-80 kg/m³thermal conductivity of 0.03 W/m³the tensile strength of the surface layer of 10.0 MPa. 1 C. p. F.-ly, 1 table. , 1 Il.

The invention relates to the field of processing of macromolecular substances to porous.

Famous CFC-free technology for producing polyurethane foam by the method of dispersion. The method is based on the saturation of the polymeric composition gas, specifically entered into the system and distributed by volume of the mixture by intensive mechanical mixing. The result is a two-phase reaction mixture with gas bubbles.

For example is used for the manufacture of polyurethane foam. The method involves the saturation of the gas in the gas chamber of one of the liquid components before they are dosed feed in the mixing head. When this component is continuously circulated from the gas chamber into the reservoir reserve, where supported by a gas cushion, from which the gas is drawn into the chamber. The gas cushion is maintained in the cell regulation, and excess gas is diverted into the stock tank. The saturation component gas by using samasamajaya hollow stirrers, which sucks the gas from the gas cushion and disperses it in a liquid component. To obtain uniform distribution of gas bubbles by volume of the components in the tank inventory provided by the stirrer, which is constantly working. The degree of saturation of the liquid components of the gas are determined by a special density meter. After all of the component located in the reservoir reaches the desired degree of saturation is submitting them to the mixing head.

The disadvantage of this method is that this method can only be implemented with negligible saturation gas liquid components (20-70% of the total), compared with use as a blowing agent f the method is the emergence of a wide range of sizes of the formed bubbles what affects the quality of the resulting polyurethane foam. In addition, the presence of special devices and systems necessary for obtaining uniform distribution of gas bubbles by volume, significantly complicate the installation as a whole.

The closest to the technical nature of the claimed invention is a method and apparatus for producing foams, particularly polyurethane foam, low reaction mixture. The essence of this method lies in the fact that for the formation of a material with the desired uniform cellular structure in the liquid ingredients before mixing dissolve the specified quantity of inert gas (air). In this first liquid component is mixed with the gas in the mixer at a pressure that is greater than the pressure dissolution (in which a specified quantity of gas must be dissolved in the component), then the received two-phase mixture is sent to a section extracts, where the gas is dissolved in the component at a pressure not lower than the pressure dissolution. The specified dissolution process takes place over a characteristic time, which lasts from the beginning of mixing components with gas before mixing component, feast upon the hinnon method introduced inert gas is an auxiliary foaming agent, which allows you to control the number and size of embryos bubbles. In addition, as the inert gas in air is used, the solubility of which in the liquid components of the polyurethane is very low, which leads to a sharp increase in the pressure of the mixture (P_see= 50 bar) compared to pressure dissolution (P_R.= 4 ATM) and complicates the system as a whole, because to achieve the desired solubility is necessary to carry out the recycling process of the liquid component. It should also be noted that, using this method, it is impossible to obtain a polyurethane foam having a low density and has both a sufficiently high mechanical characteristics.

The proposed method of producing polyurethane foam refers to CFC-free technology that allows you to avoid these disadvantages and to solve the problem on a qualitatively new level.

The aim of the invention is to develop a method of producing polyurethane foam environmentally friendly method and improved thermal and mechanical properties of polyurethane foams.

This objective is achieved in that the method involves the saturation of the gas at least one of the liquid componenta is achieved by intensive mixing of the liquid and gas electromagnetic stirrer at the given equilibrium pressure and temperature. Then saturated gas-phase components are thoroughly mixed in the unit-mixer. All of these stages of the process carried out at a pressure which may not be below the equilibrium. After that, the obtained reaction mixture is extruded through the orifice in the foaming agent is communicated with the atmosphere, in which due to the pressure drop occurs the foaming process. The resulting foam is applied on a given surface or served in the form, where its polymerization.

Thus, as a result of implementation of this method at the exit of the foaming agent is obtained formed foam of a given structure and thickness, which is a significant difference of this method from the known technological solutions used in the manufacture of polyurethane foams. As the primary blowing agent used non-toxic gases with non-polar molecules, mol. weighing not less than 40 A. E. m , such as carbon dioxide, argon, sulfur hexafluoride and other

The device for implementing the above method comprises a source of high pressure gas, dosing tanks storing a liquid component and a gas supply units, interconnected system is one of the gas supply units and simultaneously performs the role of the mixing chamber, thus simplifies the system implementation of this method, which eliminates the need for mixing heads which operate at high equilibrium pressure. In addition, the device entered the foaming agent, which is connected with a gas supply unit mixer through the orifice. The foaming agent has a curved surface profile that provides a uniform speed of advancement of foam in each section. In addition, the device is switched on the pressure compensator connected to the gas supply unit and unit-mixer through a system of shut-off and diverter valve. The device also contains instrumentation associated with the control system. The desired solubility is controlled by an electric meters, while the process of solubility occurs at a given constant temperature the volume of gas supply units.

This process has several advantages compared with prototype:
the method allows to exclude from the production of polyurethane foam any other foaming agents, such as freon or water, because gas is the primary foaming agent and its amount, nariratana with the desired properties. Thus the method allows for cleaner production of polyurethane foams. As the primary foaming agents are readily available, non-toxic gases: carbon dioxide, argon, sulfur hexafluoride, and others ;
the process of gas solubility in one or more liquid components allows the flexibility to control the number entered in the components of the gas, changing the pressure and temperature in gas supply units. When this amount of gas, such as CO₂entered into components due to dissolution when the pressure P30 bar considerably (several dozen times) exceeds the percentage of gas in case of implementation methods. This saves polymeric materials, and leads to improvement of thermal properties of the resulting polyurethane;
the method allows to achieve a uniform distribution of a given amount of gas in solution by volume of the liquid components, thereby eliminating the need for soaking section and the implementation of recycling as in the case of implementation of the method, and eliminates the need for special cameras for mixing a two-phase solution, as in the known case. In addition, the method eliminates's heart and soul is with a liquid component, which is at least twice the pressure of dissolution, which simplifies the technological solution of the system as a whole in comparison with the known;
the method allows to improve the mechanical characteristics of the resulting polyurethane foam due to the profiling of flow area of the foam, and also at the expense of drawing on a given surface formed of foam, with the necessary structure and thickness. This avoids the destruction of the formed gas bubbles and save them inside the material and leads to a narrow range of sizes of gas bubbles formed in the foamed material.

Selected features of the invention will simplify the process, to ease management and reduce the cost of the equipment and to improve the properties of the material obtained.

According to the authors of the invention, the proposed method of producing polyurethane foam has new properties.

The figure schematically depicts a device that implements the proposed method. The device operates as follows.

Dosing storage tanks 1 and 2 is filled with the necessary quantity of polyol and MDI (components a and b matched with the CSOs pressure in the pressure compensator 4, and it begins to discharge a predetermined pressure (for example, not lower than 30 bar for carbon dioxide) gas supply unit 5 through the open valve 7 and the machine-mixer 6 via the open valve 8 and the three-way valve 9. Achieving a given level of pressure is monitored by pressure gauges. After that delivery of the liquid components a and b In the gas supply units 5 and 6, respectively. With the help of the pump 10 raises the pressure in the component And to a given level and pumped it into the gas supply unit 5 through the open valve 11, simultaneously with the pump 12 through the open valve 13 in the machine-mixer 6 upload component C. thus displaced gas from unit 5 perelavlivaet in the pressure compensator 4 through the bypass system with a check valve 25, and the unit 6 through a three-way valve 9. After filing the necessary number of components a and b pumps 10 and 12 are turned off and the valves 11 and 13 are closed.

To ensure a certain solubility in the gas supply unit 5 and unit-mixer 6 is created and maintained the required constant temperature, for example, through the use of resistive heaters, built-in gas units and is equipped with a system mode liquid components by gas under pressure due to solubility. The desired solubility is achieved by intensive mixing of the liquid and the gas solenoid mixers 14 and 15. Achieving the necessary solubility is controlled by the electric flow measuring devices 16 and 17, through which the pressure compensator 4 receives the necessary amount of gas dissolved in the liquid components. Thus, in the gas supply units during the process of dissolution is constantly maintained pressure is not below the equilibrium.

Then saturated with gas-phase component And is pumped by a pump 18 through the open valve 19 in the machine-mixer 6, the pressure compensator 4 is connected to the unit to the mixer 6 via three-way valve 9, which maintains the pressure in the unit 6 at the level not below the equilibrium. Simultaneously with the pumping begins the process of mixing of liquid saturated with gas-phase components in the unit-mixer 6. After all the amount of saturated gas component And entered the Assembly-mixer 6, open the valve 20 and the reaction mixture is extruded through the orifice located in the valve 20, the foaming agent 21, the bell which communicated with the atmosphere. In Pyrkov and is in the process of foaming of the mixture. The resulting foam from the mouth foaming agent 21 is supplied to a given surface or in the volume, where its polymerization.

The socket foaming agent 21 has a complex curved shape of the flow part, the profile of which is calculated in accordance with the flow rate of the reaction mixture from the throttle opening and the speed of advancement of foam in the foaming agent so as to provide uniform expansion and exclude breaks and the formation of voids of the foam composition. It provides formed of foamed polyurethane composition having the necessary structure and geometry.

After full release of the foam Assembly-mixer 6 and the foaming agent 21 are washed with solvent, which is fed by a pump 22 from the reservoir 3 through the valve 23 and the valve 24 is closed), and then blown through the gas across the path of feed of the solvent valve 24 is open).

The method of producing polyurethane foams according to CFC-free technology is easy to implement and simple operation. When using this method, and device for its realization is obtained polyurethane foam of high quality, which according to its thermal and mechanical x is neonovymi methods (table).

P R I m e R 1. Dosing storage tanks 1 and 2 are filled with a polyol (prepared on the basis of the formulation components And Repor-2M containing freon) and polyisocyanate mark "D", respectively, at atmospheric pressure. Components are in storage tanks at a temperature not lower than the 18^aboutC. as a blowing agent is used gaseous carbon dioxide, which is supplied from a source of high pressure in the pressure compensator 4, where a pressure of the order of 33 bar. Through the corresponding opening line feed gas is blown into the gas supply units 5 and 6 to the level of the equilibrium pressure of 33 bar. After that by means of the pumps 10 and 12 raise the pressure in the liquid components a and b to 33 bar and pumped their gas supply units 5 and 6 in the ratio 1: 1.5, respectively. At the same time in the gas supply units 5 and 6 is created and maintained a constant temperature of 20^about(Using special automatic control system). Upon reaching thermal equilibrium process begins solubility of carbon dioxide in the liquid components in units 5 and 6. The process of dissolution is 1.5 minutes Then saturated with gas-phase component And is pumped by pump ia 4 through a three-way valve 9, that maintains the pressure at a level not below the equilibrium. The process of mixing the saturated gas components a and b in unit 6 lasts about 5 C. After that finished, the reaction mixture is extruded through the orifice in the foaming agent 21, which is the process of foaming and the formation of the desired structure and the thickness of the polyurethane composition. The resulting foam from the mouth foaming agent 21 is applied on a given surface, where its polymerization. The start time of polymerization of the obtained composition 17 C. After complete release of the foam Assembly-mixer 6 is filled with a solvent which is supplied by the pump 22 from the reservoir 3, and a cleaning unit 6 and the foaming agent 21. Next, the purge gas tract of the filing of the solvent through the valve 24 and the purge of the foaming agent 21 through the valve 20.

P R I m m e R 2. The procedure for obtaining polyurethane foam is similar to that described in example 1, but using other liquid components and the foaming agent, which leads only to a change of thermophysical parameters and technological regimes of the process. As a source of liquid components used polyol, made nausea agent the argon. The equilibrium pressure in the gas supply units 5 and 6, is brought to the level of 50 bar. Fluid is pumped in units 5 and 6 in the ratio A: B = 1: 1,5. The process of dissolution is 1.0 min; the process of mixing in the unit-mixer 11; time start of polymerization of 23 C. (56) the Application Germany N 3602024, CL 29 With 67/20.

The application of Germany N 3808082, CL 29 With 67/20.

U.S. patent N 4906672, CL 08 G 18/14.

The UK patent N 1417377, CL 08 J 9/30, B 01 F 15/04.

Proceedings of the Symposium on the question of the pipe insulation with polyurethane. , Vladimir; VNIIS, 28-30 Oct. 1986.

The system of pre-insulated district heating pipe. Budapest. - 1989, 26 S.

Evashevski Century B. , Ivanov Century. And. // Building materials. - 1990. - N 10, - C. 12.

1. The METHOD of producing polyurethane FOAMS, involving the use of two liquid components, the saturation of the at least one gas at a pressure not below the equilibrium, a mixture of the obtained solutions, foaming and polymerization on the surface or in the volume, characterized in that, in order to obtain polyurethane foam according to CFC-free technology and improve its mechanical and thermal characteristics, as spine 30 bar, the obtained single-phase solutions are mixed at a pressure not below the equilibrium, then the reaction mixture through the orifice squeeze in communicated with the atmosphere of the foaming agent and the formed foam is applied on the surface or in the volume.

2. The method according to p. 1, characterized in that the process of mixing the saturated gas-phase components is carried out in the unit-mixer, which is also the gas supply unit.