JPS633727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for obtaining a foaming polyurethane stock solution by mixing and discharging an active hydrogen compound-containing component and an isocyanate compound-containing component, and particularly for continuously mixing and discharging the stock solution. This invention relates to a mixing and discharging device suitable for.

A foaming stock solution is created by mixing an active hydrogen compound, such as a polyether polyol, polyester polyol, or a prepolymer containing a hydroxyl group, with an isocyanate compound, such as a prepolymer containing TDI or MDI isocyanate groups, with a foaming agent such as water or CFC. The method of foaming and curing this to obtain polyurethane foam is widely used. Various mixing and discharging devices are known as devices for obtaining this stock solution, one of which is a two-liquid mixing type mixing and discharging device. This mixing and discharging device has an active hydrogen compound as its main component, along with a blowing agent, a catalyst, and
One component containing additives such as a foam stabilizer and a component containing an isocyanate compound as a main component and optionally containing a catalyst and other additives are mixed and discharged. In some cases, just before the mixing and dispensing device,
Alternatively, another component may be added to one component immediately before the on-off valve leading to the mixing chamber of the mixing and discharging device, but basically the two components described above are mixed in the mixing chamber.

Specific details of this two-component mixing type mixing and discharging device
As an example, there is a device as described in Japanese Patent Application Laid-Open No. 52-103469. A partial sectional view of this device is shown in FIG. 1 and will be described. The main part of this device is commonly called a gun, and consists of a gun body 1 and parts attached to it. The gun body 1 has a central passage 2, and three inlets leading to the central passage 2;
There is thus an inlet tube 3 for one component to be mixed, an inlet tube 4 for the other component and a cleaning agent inlet tube 5, and one outlet leading to a tube 7 with a static mixer 6.
The center passage in front of the static mixer 6 is the mixing chamber 8,
The tip of the static mixer 6 is a discharge port 9. One component to be mixed passes from the introduction pipe 3 through one cavity 10 having a valve mechanism, and from the on-off valve 11 into the mixing chamber 8.
Similarly, other components are supplied from the cavity 12 to the mixing chamber 8 through the on-off valve 13. Each on-off valve consists of a valve seat 14 and a valve head 15.
It works when the valve head 15 closes the hole provided in the valve 4. A valve stem 16 is connected to the valve head 15,
The valve head 15 is reciprocated by the rotation of the valve actuator 19 by the cam mechanism 17 and the spring 18, thereby operating the valve. A cleaning agent such as a solvent or nitrogen is supplied to the mixing chamber 8 from the cleaning agent introduction pipe 5 through a check valve 20 provided in the central passage. This mixing and discharging device is used as follows. The two pressurized components are introduced into the gun body 1 through introduction pipes 3 and 4, respectively. Next, the two valve actuators 19 are rotated simultaneously to open and close the valves 11 and 13.
is opened, the two components collide and mix in the mixing chamber 8, and are further mixed in the static mixer 6, and the mixed stock solution is discharged from the discharge port 9. After discharging a certain amount, the valve actuator 19 is returned to its original position to close the on-off valve, and then a valve (not shown) is opened to introduce the pressurized cleaning agent into the gun body 1 through the inlet 5. The cleaning agent is supplied to the mixing chamber 8 through the check valve 20, cleans the mixing chamber 8 and the static mixer 6, and is discharged from the discharge port 9. This cleaning is usually carried out in two stages, first cleaning with a solvent, then switching a valve (not shown), introducing a gas such as nitrogen or air, and discharging the remaining solvent or stock solution. The inner surface of the target mixer 6 is dried to prepare for the next mixing discharge.

This mixing and discharging device is suitable for intermittent mixing and discharging. That is, it is convenient for repeating mixing and discharging and washing, and discharging relatively small amounts of the stock solution many times. However, it is not very suitable for continuous mixing and discharging for a relatively long period of time. The reason for this is that the check valve tends to become clogged when mixed and discharged continuously for a long time. The stock solution obtained by mixing the two components reacts rapidly and foams and hardens within a short period of time, but the stock solution mixed in the mixing chamber is not completely discharged immediately and is extremely It is unavoidable that a small amount remains in the mixing chamber. This small amount of residual stock solution is transferred to the part opposite the outlet of the mixing chamber.
That is, it tends to exist at the tip of the check valve, and if mixed and discharged for a long time, it will harden in this area, preventing the check valve from opening during cleaning. In the case of repeated intermittent mixing and discharging, the cleaning is repeated relatively quickly, so the check valve is unlikely to become clogged, but if the mixing and discharging continues for more than 20 minutes, especially for more than 30 minutes, the check valve will become clogged. clogging is extremely likely to occur. If the check valve is clogged, cleaning becomes impossible, and therefore, the gun body must be disassembled and cleaned in order to carry out the next mixing discharge, which is extremely complicated and inefficient.

Therefore, the present inventor investigated a method for preventing clogging of the check valve in the mixing and discharging apparatus shown in FIG. Such a mixing and discharging device is extremely handy and has the characteristics of being easy to operate, so it must not lose these characteristics and can also be used for intermittent mixing and discharging. Something is desirable. Therefore, we conducted various research studies to find a mechanism that separates the check valve from the mixing chamber so that the mixed undiluted solution does not come into contact with the tip of the check valve, and that also allows cleaning the mixing chamber with a cleaning agent. As a result,
The central passage is divided into two passages each having one on-off valve, each passage is provided with a check valve for supplying cleaning agent, and these two passages are connected to a mixing chamber to prevent the components flowing through each passage. It has been found that the objective can be achieved by mixing in a mixing chamber. That is, the present invention provides a first method containing an active hydrogen compound.
and a second component containing an isocyanate compound to obtain a foaming stock solution, a first on-off valve for supplying the first component to a first passage; a first check valve for supplying a cleaning agent to the first passage; a second on-off valve for supplying a second component to the second passage; and a second on-off valve for supplying the cleaning agent to the second passage. a second check valve, and a first component supplied from the first passage without going through an on-off valve and a second component supplied from the second passage without going through an on-off valve. 1. A mixing and discharging device for a foaming stock solution, characterized in that it is equipped with a mixing chamber for mixing the foaming stock solution.

The mixing and discharging device of the present invention is shown in FIG. FIG. 2 is a partial sectional view of the gun body 21, and two check valves 22 and 23 having the same structure as the check valve of the mixing and discharging device shown in FIG. 1 are not shown in the sectional view. The mechanisms of the two on-off valves 24 and 25 are the same as those shown in FIG. 1, so details will be omitted. The first component is introduced into the gun body 21 from the introduction pipe 26 as in FIG.
The cleaning agent is also supplied from the introduction pipe 28 to the first passage 27 through the first check valve 22 . Similarly, the second component is introduced into the gun body 21 from the introduction pipe 29, passes through the second on-off valve 25, and enters the second component.
The cleaning agent is supplied to the second passage 30 from the introduction pipe 31 through the second check valve 23. The first passage 27 and the second passage 30 each lead to a mixing chamber 32 in which the first component and the second component are combined and mixed.
The mixed two components are further mixed in a static mixer 33 and discharged from a discharge port 34 as a foamable stock solution. The operation is the same as in the case of Fig. 1, by opening the two on-off valves 24 and 25, mixing the two components in the mixing chamber 32 and discharging them, and after mixing and discharging a certain amount of the foaming stock solution, opening the two on-off valves 24 and 25. is closed, and then a cleaning agent is introduced from the two cleaning agent introduction pipes 28 and 31 to perform cleaning. It is preferable that the cleaning agent passes through an on-off valve (not shown) that can switch between a solvent and a gas, and then is divided into two parts and introduced into the introduction pipes 28, 31. , the cleaning agent can be supplied to the two introduction pipes 28 and 31 at the same time.

As is clear from FIG. 2, in the apparatus of the present invention, there is no chance that the foamable stock solution produced in the mixing chamber comes into contact with the tip of the check valve, so there is no risk of the check valve clogging. Moreover, the cleaning agent can completely clean not only the tip of the on-off valve, but also the passage, the mixing chamber, and the static mixer, just like in conventional equipment, and can be used not only for relatively long-time mixing discharges but also for intermittent mixing discharges. It can be done no different from conventional equipment. Also, the operation is the first
The operation is the same as the one shown in the figure, and does not become more complicated. Since the components remaining in the two passages in the device of the present invention are lost by washing, it is thought that the loss of components increases accordingly. However, it is true that the loss is large in the case of intermittent mixing and discharging as with the conventional device, but if the device of the present invention is used for continuous mixing and discharging, the loss in terms of the discharge amount is the same as that of the conventional intermittent mixing and discharging, or even less. Become. In other words, even in conventional equipment, the foaming stock solution remaining in the mixing chamber or static mixer is lost during cleaning, so the loss increases as the number of cleanings increases, but with continuous mixing and discharge, the number of cleanings increases. This is because the loss does not increase much because it is small.

The apparatus of the present invention can be modified in various ways other than that shown in FIG. For example, if the loss of two components is a problem, it is possible to make the two paths extremely short. For example, in FIG. 2, the two passages 27, 30 are shortened and the mixing chamber 32
between the two on-off valves 24 and 25, that is, move the mixing chamber to the left between the two on-off valves 2 in FIG.
Considering that it was moved between 4 and 25, 2
The main passages 27, 30 are extremely short, connecting the on-off valves 24, 25 and the mixing chamber. two check valves 2
3 and 24 each lead to this short passage,
The two components are each supplied from the on-off valve to the mixing chamber through the tip of the check valve. In this case, there is a greater risk that the foaming stock solution generated in the mixing chamber will flow back into the tip of the check valve than in the case shown in Figure 2, but even in conventional devices, when the on-off valve is open, the foaming stock solution flows back into the tip of the check valve. There is a risk that the liquid may flow back into the on-off valve, and the hydraulic pressure is adjusted to prevent backflow, so there is almost no risk of backflow in this case either. An example of the device of the present invention in which these two passages are extremely short is shown in FIG. Except for the position of the mixing chamber, the other parts are the same as the apparatus shown in FIG. 2, so a description thereof will be omitted.

Furthermore, as another example of the apparatus of the present invention, one apparatus of the present invention constructed by combining three conventional apparatuses shown in FIG. 1 will be described. In this case, an on-off valve or a check valve that does not perform any opening/closing operation during mixing discharge or cleaning is not considered an on-off valve or a check valve in the device of the present invention. Figure 4 shows this device. 2
Using any one of the on-off valves 37, 38 and the respective check valves 39, 40 of the gun bodies 35, 36 shown in FIG.
The other on-off valves 5 and 36 are always closed.
The first inlet pipe 41 of one gun body 35
components are introduced into the mixing chamber 4 through the on-off valve 37.
2 (however, since there is only one component, no mixing is performed), and then sent from the outlet of the mixing chamber 42 to the first pipe 43, which is the first passage. The cleaning agent can be supplied to the mixing chamber from the cleaning agent introduction pipe 44 through the check valve 39. Similarly, the second component is supplied to the other gun body 36 from the introduction pipe 45, passes through the on-off valve 38, and is sent to the second pipe 46.
The cleaning agent is introduced through the introduction pipe 47. first tube 4
3 and second tube 46 are the first passage and second passage in the present invention, respectively, and these two tubes are connected to a third gun body 48. The third gun body 48 has two on-off valves and one check valve, but these do not operate at all; on the contrary, the on-off valve is open, and the check valve is always closed and the cleaning agent is not allowed to flow from here. Not supplied. Therefore, these are not considered to be on-off valves or check valves in the present invention. Therefore, the third
The gun body 48 is actually only a mixing chamber 49,
Its only function is to mix the two components sent from the two pipes 43 and 46. The mixed two components are transferred to the mixing chamber 49.
The mixture is then sent to a tube 50 having a static mixer, where it is further mixed, and then discharged from a discharge port 51. The operation of this device is exactly the same as that of the device shown in Figure 2;
In the case of mixed discharge, each gun body 35, 36
Open the on-off valves 37 and 38 to send out the two components,
Mixing and discharging is carried out in the third gun body 48, and after the completion of mixing and discharging, the two on-off valves 37 and 38 are closed, and then the cleaning agent is supplied from the two cleaning agent introduction pipes 44 and 47 to perform cleaning.

This example of the device of the present invention has the feature that a conventionally used mixing and discharging device can be used as is without any modification. Moreover, since the third gun body only serves as a mixing chamber, it can be further simplified without using conventional equipment, and in fact, sufficient effects can be achieved with the use of two conventional equipment. .

In the apparatus of the present invention, the first component and the second component are each supplied to the apparatus under pressure. The pressurization may be performed using a pump or the like, but it is more preferably pressurized with pressurized gas. For example, a pressurized gas is fed into a tank storing each component, and the gas pressure transports the components from the tank to the apparatus of the present invention. It is preferable that flow rate adjustment or filtration be performed during the delivery from the tank to the mixing and discharging device. In particular, flow rate adjustment is essential to adjust the mixing ratio of two components, and it is also desirable from the perspective of flow rate adjustment to keep the temperature of the components constant not only in the tank but also in intermediate pipes to keep the viscosity constant. . The reason for sending the components using gas pressure is that using a pump tends to cause pulsations in the flow of the components, making it difficult to adjust the flow rate. Although it is preferable that the cleaning solvent is also conveyed by gas pressure, it is not necessarily limited thereto since there is little need for flow rate adjustment.

Static mixers mix fluids using the flow of fluid without having any moving parts, and there are various types of static mixers. For example, static mixers, in which many elements made of spirally twisted plates are lined up in a pipe, or elements with multiple holes at different positions on the inlet and outlet sides are lined up in a pipe are widely used. has been done. In addition, there are various mixers that do not have moving parts, such as those that use a jammer plate or the like to create turbulent flow within the tube.

The mixing and discharging device of the present invention can be modified in various ways other than those described above. For example, in a mixing chamber, the two components are introduced in a direction in which they collide with each other, but this is not necessarily the case if sufficient mixing is achieved in a static mixer; for example, the two components are introduced parallel to each other. It may also be introduced into the mixing chamber in the direction of However, in general, a static mixer does not necessarily achieve a higher stirring effect than a dynamic mixer such as a mixer with stirring blades, so the two components are collided in the mixing chamber to achieve some degree of mixing. It is preferable. Furthermore, a stirring device, which is a dynamic mixer, can be used instead of a static mixer. For example, there are devices in which stirring blades are provided in the mixing chamber and driven by a motor or the like attached to the outside of the device to perform mixing. however,
The use of dynamic mixers tends to complicate operations, complicate and enlarge the equipment, require energy sources such as electricity, and complicate cleaning and disassembly. It is recommended to use a container. Similarly,
Although it is preferable to pressurize the two components to be mixed using gas pressure, the pressure is not limited to this, and various pumps can also be used. Furthermore, the types of on-off valves and check valves are not limited to those illustrated, and various on-off valves and check valves can be used.

The apparatus of the invention is used for producing rigid, semi-rigid, flexible, etc. polyurethane foams. It is particularly suitable when it is necessary to mix and discharge a foaming stock solution continuously for a relatively long time for molding slabs, large molded products, etc. Of course, it can be used in the same way as the conventional apparatus even when it is necessary to perform mixing and discharging intermittently over relatively short periods of time as described above. In addition, the resulting foam can be used not only to produce polyurethane foam, but also to produce a foam that has many isocyanurate bonds in addition to urethane bonds, called polyisocyanate foam, which is obtained using an active hydrogen compound and an isocyanate compound as main raw materials. Further, there are two methods for discharging the foaming stock solution: a non-frosting method and a flossing method, and the device of the present invention can be used with either of them. In the case of the froth method, a blowing agent with a low boiling point such as Freon-12 is used as part of the blowing agent.

The device of the present invention is a light and small mixing and discharging device that is easy to operate and handle, and is therefore particularly suitable for producing small to medium-sized foams. moreover,
The device of the present invention is more suitable for continuous mixing and discharging than the conventional device suitable for this purpose shown in FIG. There is less clogging of the stop valve. Further, the apparatus of the present invention is not limited to the apparatus shown in FIGS. 2 to 4, and various modifications can be made depending on the configuration and purpose of the present invention.

[Brief explanation of the drawing]

Figure 1 shows a conventional two-liquid mixing and discharging device.
This example shows a gun body 1 that includes two on-off valves 11 and 13 for supplying two liquids to a mixing chamber 8, a check valve 20 for supplying a cleaning agent to the mixing chamber, and a mixing chamber 8. It consists of a tube 7 equipped with a static mixer 6 for further mixing the two liquids mixed in the mixing chamber 8. FIG. 2 shows an example of the device of the present invention which is an improvement on the conventional device shown in FIG. 1, and includes a first on-off valve 24, a first passage 27, a second on-off valve 25,
The gun body 21 includes a first check valve 22, a second on-off valve 25, a second passage 30, a second check valve 23, and a mixing chamber 32. FIG. 3 shows another example of the device of the present invention, and the second
The two passages 27 and 30 in the figure are made extremely short. FIG. 4 shows still another example of the apparatus of the present invention, in which three conventional apparatuses shown in FIG. 1 are combined to form one apparatus of the present invention.

Claims (1)

[Scope of Claims] 1. In a mixing and discharging device for obtaining a foaming stock solution by mixing a first component containing an active hydrogen compound and a second component containing an isocyanate compound,
a first opening/closing valve for supplying a component to a first passage; a first opening/closing valve for supplying a cleaning agent to the first passage;
a second on-off valve for supplying a second component to a second passage, a second check valve for supplying a cleaning agent to the second passage; and a second check valve for supplying a cleaning agent to the second passage; A mixing chamber is provided in which the first component supplied from the passage without going through an on-off valve and the second component supplied from the second passage without going through an on-off valve are combined and mixed. Mixing and discharging device for foaming stock solution. 2. The device according to claim 1, wherein the foamable stock solution obtained in the mixing chamber is further mixed in a static mixer and then discharged. 3. Apparatus according to claim 1, characterized in that the first component and the second component are introduced into the mixing chamber in a direction in which they collide with each other.