LV13955B - Method for production of carbamide plastic foam - Google Patents

Abstract

Invention is related to inorganic chemistry and can be used in the use of materials manufactured based on plastic foam for heat insulation of construction structures of various kinds. Its purpose is to develop such a method, which ensures obtaining the carbamide plastic foam of superior quality with low content of disengaged formaldehyde. The purpose is achieved by preparing two solutions of primary components, namely, the first solution with carbamide formaldehyde resin and the second solution, which contains surfactant and hardener, mixing these solutions and obtaining the foam, which is formed as result of gas pressure, when the mix moves along the pipeline to the place of forming and drying the product. The method is characterized by the fact that both solutions of primary components are directly subject to mixing, thanks to gas supply with pressure not less than 0.5 MPa, in doing so, unhomogeneous vortex flow is created in the mixer and the pipeline, but the gel-type plastic foam is obtained directly before formation of the product in the formation nozzle or the pipeline outlet by changing parameters of physical state of the mix and/or as result of impact of the mix against the obstacle, in doing so, density of the carbamide plastic foam is regulated by volume of gas flowing through the mixer, but its quality is ensured thanks to choice of optimum ratio of primary components of the solution.

Description

TECHNICAL DESCRIPTION OF THE INVENTION

The invention relates to inorganic chemistry and can be used for the production of foam-based materials for thermal insulation of various types of building structures.

Analysis of the known technical level

Techniques for preparing urea foam include the preparation of stock solution solutions, namely, separately preparing a first urea formaldehyde resin solution and a second surfactant solution with a hardener, then blending these raw component solutions, blowing and blowing the resulting foam piping through a forming nozzle to a mold, and includes curing and drying the foam mass (US Patent 3199790, 1961; RU Patent 2051799, 1996).

These techniques mainly involve the use of large tanks for foam production, but the formation of foam is effected by air supply with mechanical stirring of the foam mass. In addition, the hardener solution is usually added at the end of the process. The disadvantages of such techniques are high costs, increased production and emissions of formaldehyde, deterioration of the ecological process, as well as low productivity and poor quality of the foam.

There are known methods for preparing urea foam by preparing two solutions of the starting components, the first solution containing the urea formaldehyde resin and the second a surfactant solution together with a hardener, the second solution being added to the foam, blown with air and the resulting water-air foam in a first-stage mixer using dispersed air at a pressure of 0.25 to 0.35 MPa, and subsequently the resulting mixture, a gel-like foam, is piped through a molding nozzle to the article-forming and drying site (RU patent 2139191, 1999; RU patent 2288098 , 2005).

This technique yields a urea-formaldehyde foam with a density of 10-20 kg, an order of 20-60 and a cell size of 20-1000 mkm. A special feature of the process is the foaming of the previous second stock solution and mixing of the water-air foam with the sprayed urea-formaldehyde resin by dispersing the mixture with air at a pressure of 0.25-0.35 MPa with a consumption of 0.01-0.02 m ³ / s. These circumstances also determine the shortcomings of the method described. First, due to the prior foaming of the second solution, it is not possible to obtain the foam with the required parameters. Order is limited, there is a large dispersion of bubbles in the mass. Secondly, foam production by this technique significantly limits the ability to adjust the material density. In addition, gelling foam deposits formed on the walls of the pipeline during the curing process, which in turn reduces the productivity of the process. Finally, formaldehyde emissions from the material (4 months or more) are far too long to exceed the allowable limits for its manufacture and operation. Excessive formaldehyde release is due to the unreacted formaldehyde in the polycondensation process as well as the presence of methylol groups and methylene esters in the polymer, which is converted into methylene groups. As a result of the drying of the foam, most of the material is removed by moisture.

surfactant acid hardener modifier water The closest analogue to urea foam is known (RU patent 2277518, 2004) to prepare solutions of two starting components, the first with the urea formaldehyde resin solution and the second with the surfactant solution together with the solid, in the second solution, add a foaming agent, blend it with air, and mix the resulting water-air foam in a mixer with the first solution, disperse using air at a pressure of 0.25-0.35 MPa, then flow the resulting mixture through a forming nozzle to the formulation and drying site of the article, using as a first solution a resin composition with the following component ratio, urea to formaldehyde and ammonia to 1 to 1 to 1.45 and to 0.1 to 0.5, respectively, with the addition of modifiers , but for the resulting foam i r is the composition of the following components, w / w:

resin composition - 43.8-61.9;

0.25-0.5;

1.05-3.3;

0.015-0.17;

35.6-53.2.

This technique has the advantage of reducing the concentration of formaldehyde released during foam production and drying. This is achieved, firstly, by the resin synthesis and, secondly, by using a resin composition with a modifier, whereby the resin with the given molar ratios of components (urea to formaldehyde and ammonia) releases formaldehyde from the material as early as 3-5 days after foam production. 10-30 times less than other foams. At the same time, this process fails to completely eliminate formaldehyde, especially during the manufacturing process.

The principle of foam production, by pre-foaming the second solution and mixing it with the resin composition in the subsequent process, increases the material volume of the components, but making a solution of the first component requires a large amount of water two to three times the resin volume. This is due to the fact that the gel-like foam can harden in the pipeline.

The large amount of water increases the drying time of the material. In addition, the liquid released from the foam retains excess raw material components. In addition, this technique is labor intensive in the industrial production of foam, since the density of the final product can only be adjusted by changing the composition of the raw components, but their metered delivery does not significantly alter the parameters of the final product.

Purpose and substance of the invention

The object of the present invention is to provide a process for obtaining high quality urea foam with a low release formaldehyde content.

The object is achieved by preparing two solutions of the starting components, namely the first solution with the urea formaldehyde resin and the second solution containing the surfactant and the hardener, mixing these solutions to obtain a foam formed by gas pressure, moving the mixture through the product to form drying place. The process is characterized in that both raw material solutions are directly subjected to mixing due to a gas pressure of not less than 0.5 MPa, whereby an uneven mixture vortex is formed in the mixer and in the pipeline, while the gel foam is obtained just prior to forming the product in the nozzle. or at the outlet of the pipeline by changing the physical state of the mixture and / or by impingement of the mixture against the barrier, the urea foam density is controlled by varying the volume of gas flowing through the mixer but is optimized by the optimum ratio of air, nitrogen, carbon dioxide or other inert gases, but changes in the volume of gas flowing through the mixer are controlled by measuring the gas pressure at the mixer inlet.

The proposed method differs from the prototype in that the mixing of the solutions of the two starting components is effected by means of compressed gas directly under the influence of an uneven vortex flow in the mixer and in the pipeline. This results in a qualitative mixing process that provides a monodisperse foam mass. In addition, the supply of compressed gas allows the mixture to be saturated with this gas by altering the physical state of the mixture, for example by changing the pressure at the outlet of the pipeline and / or by bouncing the mass against an obstacle in the forming nozzle. The combination of these new operations and the gas flow regulator provide foam bulk density control without changing the composition of the starting components. Such foaming significantly reduces the amount of formaldehyde. Thus, a set of new operations and modes of operation ensures the technical result of the applied method.

DETAILED DESCRIPTION OF THE INVENTION

A schematic diagram of the apparatus for carrying out the proposed process is shown schematically in Fig. 1, where the urea foam extraction apparatus consists of two raw material preparation tanks (1,2), the second tank having a mixer and heating elements not shown in the diagram. These receptacles (1) and (2) are connected to the respective inputs of the mixer (9) by means of a pump (3, 4) with a common feed (5) and a receiver (6, 7), the receiver (7) and the regulator (8). ) connected to the mixer, but the gas source (10) is connected to the gas flow regulator (11) (gas receiver) with the corresponding inlet of the mixer (9) and the outlet of the mixer (9) is connected to the forming nozzle (14). with a coil (not shown in the figure) which serves to stop the mass jet and provides additional mass foaming and the removal of excess gas, the outlet of the forming nozzle (14) being connected to a mold (15). In addition, a pressure gauge (12) is connected to the outlet of the flow controller (11).

The process for obtaining urea foam is carried out as follows. First, two solutions of the starting components are prepared in the tanks (1, 2): in the tank (1) a solution containing urea formaldehyde resin, in the tank (2) a solution with a surfactant and a hardener. For the preparation of the first solution, a resin composition with a resin ratio is used: urea to formaldehyde and ammonia are treated in the same way as 1 to 1 to 1.45 and 0.1 to 0.5, with the addition of modifiers.

This resin is manufactured under two grades - BIC and Kap6oMem T (RU patent 2114870, 1998 and RU patent application 2003102351, 2003, respectively) and with a solids concentration of 50-55%. The peculiarity of the process is that the resin composition is not diluted with water.

For the second solution, grade A alkylbenzosulfonic acid (TY 2481-036-046893-75-95) or orthophosphoric acid hardener (FOCT 6552-80) is usually selected as the surfactant, but their ratio in the composition is determined by optimizing the ratio of the foam quality assurance % by weight, namely:

resin composition - 43.8 - 61.9;

surfactant - 0.25 - 0.5;

hardener - 1.05-3.3;

water 35.6-53.2.

Subsequently, the selected amount of surfactant and hardener are mixed with water in the tank (2), heated to 30-40 ° C and maintained throughout the production of urea foam by heating elements.

The resulting solutions are transferred by means of pumps (3, 4) and receivers (6, 7), but the second solution is also transferred via the regulator (8) to the appropriate inputs of the mixer (9). Thus, due to the introduction of compressed gas in the mixer under pressure of not less than 0.5 MPa and the uneven vortex flow of the mixture in the pipeline, both raw material solutions are subjected to mixing.

Air is usually used as gas, but inert gases such as nitrogen, carbon dioxide, etc. can also be used. This enables the production of urea foam with additional functions, extending its use. In the method, gas from the source (10) is fed through the gas flow regulator (11) (gas receiver) to the corresponding entrance of the mixer (9). Due to the particular embodiment of the mixer (9), vortex flows are formed in the mixer (9) and in the pipeline (13), the solutions of the starting components are mixed and the mixture of the starting components is mixed with gas-saturated water. In addition, the vortex flow may be formed in various ways, for example by positioning the impeller in the flow path or by feeding the gas into the mixer (9) at an appropriate angle.

The resulting mixture from the mixer (9), via a conduit (13) formed, for example, as a flexible flexible tube 4-20 mm in diameter, is passed through a forming nozzle (14) to a mold (15) for hardening and drying of the foam. In addition, it should be noted that foaming, gelling of foam is carried out immediately prior to forming the article at the nozzle or at the outlet of the pipeline, with changes in the physical state of the mixture and / or as a result of the impact of the mixture against the barrier.

In this case, the density of the urea foam, unlike known techniques, is controlled by changing the volume of gas flowing through the mixer (9), controlling it by means of a manometer (12) and changing it by means of a gas flow regulator (11).

By implementing this method, it is possible to change the stock solutions in the manufacturing process, since foam of different densities can be obtained only by changing the volume of gas supplied to the mixer (9), and quality can be ensured by regulating the consumption of the second solution.

A specific example of a method implementation

Urea formaldehyde foam is obtained as follows. The resin composition used is KAPBOMET-T (concentration 51.2%), as surfactant grade A alkylbenzosulfonic acid (concentration 85%), as a curing agent orthophosphoric acid (concentration 96%). The modifier is not used.

Initially, undiluted urea formaldehyde resin is poured into the first container. In the second tank, prepare the surfactant solution with a hardener. To obtain InT foam, take whatever is needed, 40 ml of surfactant and 75 ml of hardener (orthophosphoric acid), which are mixed with 10 liters of water and fill the tank (2) according to the volume ratio. Mix the surfactant and the hardener in the tank (2) with a mixer and stir for 3-5 minutes. The resulting solution is then heated to 35 ° C and maintained at this temperature throughout the manufacturing process. The prepared solutions are simultaneously fed to the respective inlets of the mixer (9) by means of pumps (3) and (4).

The positive effect of the process, as stated above, is that it is possible to obtain urea foam of different densities only by changing the gas consumption through a mixer (9) controlled by a manometer (12). For example, with a regulator (11), we set a pressure of 0.71 MPa to a density of 15 kg / m ³ . As a result, the obtained foam density parameters are obtained by consuming 16.0 1 / m ^{3 of} urea formaldehyde resin and 15.2 1 / m ^{3 of} surfactant solution with hardener.

The finished urea foam gel mixture is then placed in a mold (15), cured for 4 hours, then the material is removed from the mold and finally dried, for example on scaffolding shelves for 5 days at 25 ° C and 50% relative humidity. .

Examples of different production variants of urea foam of different densities are summarized in the following table, which also provides data for the prototype. The research carried out shows that the obtained urea foam has higher properties than the known one, in particular - it is possible to obtain different densities without changing the composition of the starting components, which consumption is 5-10% less than in the prototype. As a result, urea foam of order 80-160 with bubble size 20-40 mkm, humidity 50-60%, water absorption 3-7% and shrinkage not more than 5-10% is obtained.

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Required amount in liters per 1 m ³ Invention 13.5 15 ± 1 ι / Λ o i-4 θ ' 0.05 CS o st .-1 in θ ' 0.06 IT) Ol <N st m 0.226 0.212 C'l T m 0.55 0.035 20th 26.0 ± 1 0.165 0.085 ¹ 21.0 ± 2 0.6 0.042 0.06 and τ-P -H o. kO Γ 0.113 0.06 i-1 -H <o is a? t-1 τ-P θ ' o n θ ' 0.071 Prototype 20th • st -H o θ ' m v ~> cn θ ' 1 — i θ ' +1 V m CO θ ' 0.02 and r-1 and Ή o <N 0.25 ί r-P θ ' l> θ ' no 0.3 0.02 Concentration (%) Density of urea foam in kg / m ³ o © i-1 85 96 Material KAPBOMET-T resin composition Modifier Hardener. Surface active agent Water Pressure, MPa % m s > ιζΓ • r-M IO 13th P Pressure, MPa Consumption, m ³ / s. Solution, gas Resins Foam Bright Ozone

The low release of formaldehyde and the controllability of the production process make it possible to use the foam obtained in the construction of residential, agricultural and industrial buildings as heat insulation material.

Claims (3)

1. A process for preparing urea foam by preparing two solutions of the starting components, namely, a first solution containing a urea formaldehyde resin and a second solution containing a surfactant and a hardener, mixing these solutions to form a foam formed by gas pressure while moving the mixture through the pipeline. forming and drying of the product, characterized in that both raw material solutions are directly subjected to mixing, due to a gas pressure of not less than 0.5 MPa, whereby an uneven mixture vortex is formed in the mixer and in the pipeline, and the gel foam is obtained directly prior to forming the article at the nozzle or at the outlet of the pipeline by altering the physical state of the mixture and / or by impacting the barrier against the barrier, wherein the density of the urea foam is controlled by varying the volume of quality is guaranteed thanks to the optimal solution izejkomponentu ratio selection. A process according to claim 1, characterized in that air, nitrogen, carbon dioxide or other inert gases are used as the gas. Method according to claim 1, characterized in that the change in the volume of gas flowing through the mixer is controlled by measuring the gas pressure at the inlet of the mixer.