JP2706991B2 - Production equipment for foaming urethane stock solution - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for producing a raw foaming urethane solution.

2. Related Art and its Problems Conventionally, as a foamable urethane stock solution, a solution prepared by adding a liquid foaming agent such as trichloromonofluoromethane at room temperature to a polyol stock solution has been proposed. When this foamable urethane stock solution is mixed with the isocyanate stock solution, the foaming agent (liquid) is vaporized by the heat of reaction, and a urethane foam having good heat insulating properties can be obtained by simply mixing the two liquids. In addition, it can be achieved simply in terms of operation.

However, trichloromonofluoromethane, which is liquid at room temperature and is often used as a foaming agent, has the property of destroying the ozone layer in the atmosphere, and its production and use tend to be prohibited. In addition, a blowing agent that is liquid at room temperature, such as water, methylene chloride, and pentane, has no danger of destruction of the ozone layer, but has a problem of poor heat insulation performance.

Dichlorodifluoromethane, which is gaseous at room temperature, has the advantage of excellent heat insulation, but has the risk of destroying the ozone layer, and because it is a gas at room temperature, high-pressure injection is required, which complicates equipment and operation. Not only that, since the cells are easily communicated with each other, they are not suitable for producing a closed-cell, heat-insulating foam.

The present invention has been made to eliminate such a conventional problem.

Means for Solving the Problems The present invention relates to a supply section of a gas for foaming a gas at room temperature, an adsorption tower for adsorbing the gas from the supply section to silica gel particles filled in the tower, a supply section of a polyol stock solution, and the adsorption section. The present invention relates to an apparatus for producing a foamable urethane stock solution, comprising a mixing tank for mixing gas-adsorbed silica gel particles from a column and a polyol stock solution from the above-mentioned supply unit.

In the present invention, for example, a pressure vessel is provided in the supply section of the foaming gas, and the foaming gas is stored in the vessel.
The foaming gas is a gas at normal temperature, and it is necessary that there is no danger of destruction of the atmospheric ozone layer and that the polyol be inert with respect to the stock solution. Such foaming gases include monochlorodifluoromethane, difluoroethane, and monochlorofluoromethane. Examples include difluoroethane.

If the particle size of the silica gel particles filled in the adsorption tower is too large, it may adversely affect the physical properties of the urethane foam.If the particle size is too small, it is miscible with the polyol stock solution and moldability into a fine shape after mixing. 20 to 150μ, preferably 3
Those having a size of about 0 to 75 μm are used.

Foaming gas is supplied into the adsorption tower from the gas supply unit using the storage pressure, and this supply is continued until the silica gel particles reach or reach the limit of gas adsorption. In order to perform gas adsorption efficiently, gas may be injected into the particle layer. In the process before performing the gas adsorption operation,
The heating and regeneration of the silica gel particles and the suction and discharge of the air in the tower containing the impurity component may be performed.

Silica gel particles can usually adsorb a gas of up to about 1: 0.4 to 0.6 (weight ratio) by contact with the above gas.

The silica gel particles having adsorbed the foaming gas are supplied into the mixing tank from the adsorption tower, and mixed with the liquid liquid supply unit, for example, the polyol stock solution supplied from the liquid tank, in the tank. A stirrer is obtained in the mixing tank to perform this mixing.

The mixing ratio between the polyol stock solution and the silica gel particles can be selected from a wide range.
The amount is set to be about 0.1 to 0.3 mol per gram.

By mixing the foaming gas-adsorbed silica gel particles and the polyol stock solution in the mixing tank in this way, a urethane foam stock solution is obtained.

When this urethane foam stock solution and the isocyanate stock solution are mixed together with various known additives such as a catalyst, a crosslinking agent, a foam stabilizer, and a filler, a foaming gas is desorbed from the silica gel particles by the heat of reaction of the two stock solutions, and foaming occurs. The urethane foam is obtained as usual.

Embodiments Various embodiments of the apparatus of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the apparatus of the present invention, in which, for example, a pressure vessel (1) is provided in a supply portion of a foaming gas, and the gas is stored under high pressure in the vessel (1). I have. The pressure vessel (1) is connected via a gas supply line (4) equipped with a regulator (2) and a valve (3) to a gas inlet with mesh (6) at the top of the adsorption tower (5). At the lower part of the adsorption tower (5), there is an exhaust valve (3a ') connected to the gas exhaust port with mesh (6').

The adsorption tower (5) is filled with silica gel particles, and the lower end of the tower (5) is connected to a mixing tank via a powder supply line (9) equipped with a powder valve (8) and a metering pump (7). (1
0) is connected to the top.

Above the mixing tank (10), there is provided a supply part of a polyol stock solution, for example, a liquid tank (11). The lower end of the tank (11) has a liquid supply line provided with a valve (12) and a measuring pump (13). It is connected to the top of the mixing tank (10) via (14).

The mixing tank (10) is provided with a stirrer (15) for positively mixing and stirring the particles and the stock solution. In addition, tank (10)
Extraction line (17) with metering pump (16) at the lower end of the
The other end of the line (17) is connected to a packaging line or a urethane foam production line (not shown). A return line (18) to the tank (10) is branched from the middle of the line (17), and the branch point is provided with a three-way valve (19).

In the production of foaming urethane stock solution, first,
Foaming gas is supplied from the pressure vessel (1) with the valve (3) open to the adsorption tower (5) through the line (4), and this gas supply reaches the limit or near the limit of the gas adsorption of the silica gel particles. Continued until At this time, the valve (3a ')
Is open, and it is possible to know the adsorption state of silica gel by the gas concentration from the outlet.

After finishing the gas adsorption operation, the valve (3) is closed, while the valve (8) on the powder line (9) is opened and at the same time the metering pump (7) is driven. Thus, gas adsorbed particles are supplied from the adsorption tower (5) into the mixing tank (10) through the line (9). After the supply amount reaches the specified amount,
The valve (8) is closed and the drive of the pump (7) is stopped.

In the mixing tank (10), a predetermined amount of the polyol stock solution is supplied from the liquid tank (11) via the line (14) to the valve (12).
By operating the metering pump (13), the adsorbed particles are supplied before or after the supply.

Therefore, the stirrer (15) operates in the mixing tank (10),
By mixing and stirring the gas adsorbed particles and the polyol stock solution, a foamable urethane stock solution is obtained.

The foaming urethane stock solution is driven by the operation of the metering pump (16) on the line (17) and the opening of the three-way valve (19) toward the tip.
It is taken out to the packaging line or the production line.

If the unloading of the undiluted solution is performed intermittently, while the unloading is stopped, sedimentation of the silica gel particles occurs in the line (17) or the like, which may cause uneven dispersion. The problem of non-uniform dispersion is eliminated by returning the urethane stock solution into the tank (10) through the reflux line (18) and stopping the circulation between the tank (10) and the reflux line (18) during the supply stop. it can.

When the foamable urethane stock solution and the isocyanate stock solution obtained from the production apparatus of the present invention are mixed with various known additives, foaming gas is desorbed from the silica gel particles by the heat of reaction, foaming occurs, and a urethane foam is obtained as usual. .

FIG. 2 shows a second embodiment of the apparatus of the present invention, which is of a multi-tower type and has a structure capable of producing a foaming urethane stock solution substantially continuously.

In this embodiment, three adsorption towers (5a) to (5c) are installed, and the pressure tank (1) and the inlets (6a) to (6c) with mesh at the top of each tower are gaseous. They are connected via a supply line (4) and branch lines (4a) to (4b) with valves (3a) to (3c) branched from each column. Each tower (5a)
~ (5c) is a gas mesh outlet (6a ') at the bottom
'I have a respective outlet (6a (6c)') ~ (6c ') , the tower after one through the valve _{(3a 1) ~ (3c 1} ) with connecting lines _{(4a 1) ~ (4c 1} ) Are connected to the inlets (6b), (6c) and (6a) at the top of the column to form a closed circuit.

The lower end of each tower (5a)-(5b) is a powder valve (8a)-
(8c) and connected to the top of the mixing tank (10) via powder lines (9a) to (9c) with metering pumps (7a) to (7c).

Three tanks of polyol stock solution tanks (11a) to (11c) are installed, and each tank (11a) to (11c) has a valve (12a) to
It is connected to the mixing tank (10) via liquid lines (14a) to (14c) provided with (12c) and measuring pumps (13a) to (13c). The other configuration is substantially the same as that of the first embodiment.

In the present embodiment, when performing gas adsorption, first, the valves (3a) (3a ₁ ) attached to the first column (5a);
Further, the bottom valve (3b ₁ ) associated with the second column (5b) is opened. Thus the gas pressure vessel (1) in the line (4) and (4a) from the first column (5a) in further connection line (4a ₁₎ and (4b ₁₎ through the second tower (5b) and the While being supplied into the third column (5c) and continuing the gas supply, gas adsorption by the silica gel particles is performed from the first column (5a) to the second column (5b) and the third column (5c). Go step by step.

After it is confirmed by gas supply that the gas adsorption in the first column (5a) has reached the adsorption limit or near the limit, for example, by comparing the flow rate between the inlet and the outlet of the column (5a), the first column
The upper and lower valves (3a) and (3a ₁ ) associated with the tower (5a) are closed, while the top valve (3b) associated with the second tower (5b) is opened and the second tower (5b) and (3b) are opened. The adsorption operation of the third column (5c) is continued. Utilizing the period during which the adsorption operation is continued, discharge of gas adsorbed particles from the first column (5a) to the mixing tank (10) and packing of the non-adsorbed particles with the third column (5c) are performed. by an opening on the bottom side of the valve that is included (3c ₁₎ on),
The stepwise adsorption operation in the second column → the third column → the first column is started.

Utilizing during the adsorption operation, the mixing operation of the gas adsorbed particles from the first column (5a) and the undiluted polyol solution from the first liquid tank (11a) in the mixing tank (10) is performed. The obtained foaming urethane solution is discharged out of the tank, and the mixing tank (10) is prepared for the next mixing operation.

After the completion of adsorption in the second column (5b) is confirmed, the upper and lower valves (3b) (3b ₁ ) attached to the column (5b) are closed, while the upper and lower valves (3b ₁ ) attached to the third column (5c) are closed. The top valve (3c) is opened, and the adsorption operation of the third column (5c) → the first column (5a) is continued. Utilizing this feeling of continuation, the discharge of the adsorbed particles from the second column (5b) is performed by filling the non-adsorbed particles.
By opening the valve (3a ₁ ) at the bottom of the first tower (5a), the third tower (5a) is opened.
c) Stepwise adsorption in the first column (5a) → the second column (5b) is resumed.

During the stepwise adsorption operation, the mixing operation in the mixing tank (10) and the discharging of the foamable urethane stock solution obtained by the mixing operation to the outside of the tank are performed as described above, and the next operation is performed. Prepare for.

Hereinafter, by repeating such an operation, a foaming urethane stock solution can be produced substantially continuously.

In FIG. 2, (a) shows a mixing head of a urethane foam production apparatus, in which a foamable urethane stock solution obtained from the production apparatus of the present invention and a liquid tank (b) are shown. By mixing the isocyanate stock solution in the presence of various additives, a urethane foam can be produced.

FIG. 3 shows a third embodiment of the apparatus of the present invention, which is substantially the same as that of the embodiment of FIG. 1 except that it is configured to purify silica gel particles and recover excess gas. There is no difference.

In this embodiment, the silica gel particles are supplied from the adsorbent inlet (20) through the line (22) with the powder valve (21) into the adsorption tower (5). It is heated and dried by a heat exchanger (23) and purified.

During the heating and drying step of the silica gel particles, the evacuation from the inside of the adsorption tower (5) is continued, and the inside of the tower (5) is maintained in a negative pressure state. Exhaust from the tower (5) is performed by driving a pump (25) provided on an exhaust recovery line (24) which continues the top of the adsorption tower (5) and the pressure tank (1). Inside, the three-way valve (26) on the line (24) is open to the atmosphere, and the valve (27) is kept open.

After purification of silica gel particles, heat exchanger (23)
And the operation of the pump (25) is stopped, and the valve (27) is closed. In this state, the inside of the tower (5) is cooled to room temperature. This cooling may be positively performed using the heat exchanger (23).

Next, gas is supplied from the pressure tank (1) through the line (4) into the adsorption tower (5). During the gas supply, the valve (3) on the line (4) is opened and the three-way valve (28) is opened. )
Are open to the adsorption tower (5).

Since the gas adsorption in the adsorption tower (5) is performed in a state where the silica gel particles are purified and air is exhausted from the column, the gas can be efficiently and quickly brought to the saturated adsorption state.

After finishing the gas adsorption operation, the valve (3) is closed, and the gas supply into the tower (5) is stopped. Note that the inside of the tower (5) is in a gas excess supply state, and is maintained in a pressurized state.

Next, when the powder valve (8) on the powder supply line (9) connecting the tower (5) and the mixing tank (10) is opened, the silica gel particles in the tower (5) 10), and the pressure in the adsorption tower (5) decreases as the supply proceeds.

The supply of the silica gel particles from the adsorption tower (5) to the mixing tank (10) can be performed in a state where the inside of the mixing tank (10) is at a negative pressure. This negative pressure operation is performed by driving a pump (30) on an exhaust gas recovery line (29) connecting the mixing tank (10) and the pressure tank (1).
9) The upper three-way valve (31) is open to the atmosphere, and the valve (32) is open. After the operation, the pump (30) is stopped and the valve (32) is closed.

The gas-adsorbed silica gel particles supplied into the mixing tank (10) are mixed with the undiluted polyol solution from the undiluted liquid tank (11) in the same manner as in the previous embodiment, and then discharged as a product outside the tank. In order to smoothly discharge the gas to the outside of the tank, the inside of the tank (10) may be maintained in a gas pressurized atmosphere, and the pressurized gas may be used to perform the pushing action. To supply gas into the mixing tank (10), the three-way valve (28) on the line (4) is connected to the mixing tank (10).
This can be done by opening to the side and supplying gas into the tank (10) through the branch line (33). Three-way valve (28)
After the gas supply to the mixing tank (10) is completed, the gas is immediately opened to the adsorption tower (5) side.

After supplying the gas-adsorbed silica gel particles to the mixing tank (10), excess gas remains in the adsorption tower (5). This excess gas is collected in the pressure tank (1) using the line (24). During this recovery operation, the three-way valve (26) on the line (24) is opened to the pressure tank (1) side, and the pump (25) is driven with the valve (27) open. After the collection, the pump (25) is stopped and the three-way valve (26)
Is opened to the atmosphere side, and the valve (27) is further closed. Therefore, the inside of the adsorption tower (5) is in a negative pressure state, and preparations are made for the introduction of silica gel particles from the inlet (20).

During the repeated production of the foaming urethane stock solution, the inside of the mixing tank (10) can be kept in the atmosphere of the foaming gas. When the production is stopped, the gas in the mixing tank (10) can be collected in the pressure tank (1). At the time of this collection, the line (29)
The upper three-way valve (31) is opened to the pressure tank (1) side, and the pump (30) is driven in this state.

As described above, in the third embodiment, excess gas in the adsorption tower (5) and the mixing tank (10) can be appropriately collected in the pressure tank (1). In Figure 3, (34), (35)
And (36) are check valves.

Hereinafter, the mixing ratio of each component of the raw foaming urethane solution obtained from the production apparatus of the present invention is specifically shown as follows.

[Example 1] Polyol stock solution 100 parts by weight Silica gel particles 65.0 parts by weight (75μ) Monochlorodifluoromethane 11.6 parts by weight [Example 2] Polyol stock solution 100 parts by weight Silica gel particles 65.7 parts by weight (75μ) Difluoroethane 11.6 parts by weight [Example 3] Polyol stock solution 100 parts by weight Silica gel particles 76.7 parts by weight (75μ) Monochlorodifluoromethane 21.4 parts by weight [Example 4] Polyol stock solution 100 parts by weight Silica gel particles 60.8 parts by weight (75μ) Difluoromethane 10.1 parts by weight Foaming urethane stock solution of Examples 1 to 4 and isocyanate An example of the specific gravity and thermal conductivity of a urethane foam obtained by mixing a stock solution with various known additives is as follows.

Effect In the production apparatus of the present invention, the foaming gas, which is a gas at normal temperature, is adsorbed on the silica gel particles and is mixed into the polyol stock solution, so that the amount of gas necessary for foaming is preliminarily stabilized in the polyol stock solution. It is possible to mix them. Therefore, irrespective of the use of the foaming gas at room temperature, the production of urethane foam can be easily performed using a simple apparatus in the same manner as the mixing of the urethane foam stock solution using the foaming liquid at room temperature. Can be done at Further, since a gaseous substance at room temperature is used as the foaming agent, there is no danger of destruction of the atmospheric ozone layer, which can contribute to the protection of the atmospheric environment. Further, there is no need to inject high-pressure gas irrespective of the use of a gas for foaming at room temperature, so that there is no danger of deteriorating the working environment of urethane foam production.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a first embodiment of the present invention,
FIG. 2 is an explanatory view showing the second embodiment, and FIG.
It is explanatory drawing which shows Example of this. In the figure, (1) is a pressure vessel, (2) is a regulator,
(3) is a valve, (4) is a line, (5) is an adsorption tower,
(6) is an inlet, (7) is a metering pump, (8) is a powder valve, (9) is a line, (10) is a mixing tank, (11) is a liquid tank, (12) is a valve, (13) ) Is a metering pump, (14)
Is a line, (15) is a stirrer, (16) is a metering pump, (1
7) is a line, (18) is a reflux line, and (19) is a three-way valve.

Claims (1)

(57) [Claims] 1. A supply section of a gas for foaming a gas at normal temperature, an adsorption tower for adsorbing the gas from the supply section to silica gel particles filled in the column, a supply section of a polyol stock solution, and gas-adsorbed silica gel particles from the adsorption tower. And a mixing tank for mixing the undiluted polyol and the undiluted polyol from the supply unit.