Foaming agent adding device, spray foaming machine, foaming agent adding method, and foam manufacturing method

Abstract

To provide a foaming agent addition device, a foaming machine for spraying, a foaming agent addition method and a foam production method which can stably supply a foaming agent to a liquid flowing through a liquid flow path.SOLUTION: A device for adding a foaming agent E to a liquid L1 that is supplied by a liquid pump 40 and flows through a flow path 30 includes: a flow path pressure gauge 31 of the flowing liquid L1; a drive detection part 41 of the liquid pump 40; a storage container 11 of the foaming agent E; a foaming agent flow path 12 for flowing the foaming agent E supplied from the container 11; a pressure gauge 81 of the foaming agent E flowing through the foaming agent flow path 12; a foaming agent pressurization pump 80 for pressurizing the foaming agent E flowing through the foaming agent flow path 12 so that the pressure of the foaming agent E is lower than the liquid pressure; a foaming agent measuring pump 50 for supplying a predetermined amount of the foaming agent E to the flow path 30; an open / close valve 60 for controlling addition of the foaming agent E to the liquid L1; and a control part 61 for controlling the open / close valve 60 according to a driving state of the pump drive detection part 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a foaming agent adding device for adding a foaming agent to a liquid, a spray foaming machine, a foaming agent adding method, and a foam manufacturing method. [Background technology]

[0002] Conventionally, a widely known construction method involves mixing polyol and isocyanate on-site onto the roof, wall, floor, etc. of a building or structure, and then spraying and foaming the mixture to form polyurethane foam. A widely known method for enhancing the workability of polyurethane foam is, for example, a method in which a blowing agent is added as a third component when mixing two components, polyol and isocyanate (hereinafter referred to as the "froth method"). In the froth method, a blowing agent flow path is provided that is connected to a liquid flow path for supplying, for example, polyol or isocyanate. A blowing agent addition device is generally used that adds a blowing agent, such as carbon dioxide, from a tank or the like to the polyol or isocyanate in the liquid flow path via the blowing agent flow path. The polyol or isocyanate to which a blowing agent, such as carbon dioxide, has been added in the blowing agent addition device is further mixed with the isocyanate or polyol and then discharged to the outside.

[0003] The liquid in the liquid flow path of a foaming agent addition device is generally supplied under pressure, and the foaming agent can be stably mixed with the liquid by being pressurized to a pressure higher than the liquid pressure in the liquid flow path and then added to the liquid flow path. Therefore, a device is used that measures the liquid pressure in the liquid flow path and the foaming agent pressure in the foaming agent flow path, and opens an on-off valve to add the foaming agent to the liquid when the foaming agent pressure is higher than the liquid pressure (see, for example, Patent Document 1). Also disclosed is a device that heats a foaming agent container to increase the foaming agent pressure to a pressure higher than the liquid pressure in the liquid flow path without using a foaming agent pump, thereby controlling the addition of foaming agent to liquid based on the differential pressure between the foaming agent pressure and the liquid pressure (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6395556 [Patent Document 2] Patent No. 5255239 [Patent Document 3] Patent No. 5255380 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional foaming agent addition devices, the foaming agent pressure must be higher than the liquid pressure as a condition for adding the foaming agent, and therefore the addition of the foaming agent is controlled while detecting the liquid pressure in the liquid flow path. However, in conventional foaming agent addition devices, the liquid flowing through the liquid flow path is supplied in a pulsating manner by a liquid pump, and therefore the liquid pressure in the liquid flow path is easily affected by the pulsation of the liquid pump, making it difficult to control the addition of the foaming agent using a control method that responds to the liquid pressure. Furthermore, the amount of foaming agent added varies depending on the pressure difference between the liquid pressure and the foaming agent pressure when the on-off valve is opened to add the foaming agent to the liquid, and on the time the on-off valve is open, making it difficult to quantitatively determine the amount of foaming agent added and to adjust the amount of foaming agent added. Furthermore, in the blowing agent addition device, the provision of a blowing agent pressure pump that pressurizes the blowing agent in the blowing agent passageway to stabilize the pressure in the blowing agent passageway has been considered. However, when the blowing agent pressure in the blowing agent passageway is increased by the blowing agent pressure pump, the burden on the blowing agent pressure pump that pressurizes the blowing agent increases, making it difficult to maintain the pressure of the blowing agent and making it difficult to adjust the amount of blowing agent added. Furthermore, in a blowing agent addition device, from the viewpoint of preventing backflow from the liquid flow path to the blowing agent flow path, the provision of a blowing agent pressure pump that pressurizes the blowing agent in the blowing agent flow path has been considered in order to maintain the blowing agent pressure at a higher pressure than the liquid pressure. However, when the blowing agent pressure is increased by the blowing agent pressure pump to maintain the blowing agent pressure at a high pressure, it is necessary to increase the blowing agent pressure in the blowing agent container to reduce the difference between the blowing agent pressure in the blowing agent container and the blowing agent pressure increased by the blowing agent pressure pump. If the pressure in the blowing agent container is increased by, for example, heating the blowing agent container, there is a risk of increasing the equipment cost for heating the blowing agent container and overpressurizing the blowing agent container. Maintaining a high blowing agent pressure by pressurizing only the blowing agent pressure pump without increasing the pressure in the blowing agent container results in a large difference between the pressure in the blowing agent container and the pressure increased by the blowing agent pressure pump, resulting in a delay in the increase in the blowing agent pressure and making it difficult to adjust the amount of blowing agent added. Furthermore, carbon dioxide is often used as the foaming agent to be added from the viewpoint of cost reduction. Carbon dioxide as an additive is easily vaporized, and the pressure of carbon dioxide in the foaming agent container tends to become higher than usual, especially under high temperatures such as in summer. In conventional foaming agent adding devices, a flow path is connected from the foaming agent container to an on-off valve that controls the amount of foaming agent added to the liquid. Therefore, when the pressure of the foaming agent in the foaming agent container becomes high, the pressure difference between the foaming agent and the liquid pressure in the liquid flow path increases, making it easy for excessive foaming agent to be added, and making it difficult to adjust the amount of foaming agent added.

[0006] Therefore, an object of the present invention is to provide a foaming agent addition device, a spray foaming machine, a foaming agent addition method, and a foam manufacturing method that are capable of stably supplying a foaming agent to a liquid flowing through a liquid flow path without being affected by the pulsation of the liquid pump by controlling the foaming agent in response to the drive of the liquid pump rather than the liquid pressure in the liquid flow path. Another object of the present invention is to provide a foaming agent adding device, a spray foaming machine, a foaming agent adding method, and a foam manufacturing method that are capable of supplying a predetermined amount (predetermined volume) of foaming agent to a liquid flowing through a liquid flow path by utilizing a foaming agent metering pump that supplies a predetermined amount of foaming agent to the liquid flowing through the liquid flow path. Another object of the present invention is to provide a foaming agent adding device, a spray foaming machine, a foaming agent adding method, and a foam manufacturing method that, when a foaming agent pressure pump is used, can reduce the burden on the foaming agent pressure pump, maintain the function of the foaming agent pressure pump, and stably supply the foaming agent. Another object of the present invention is to provide a foaming agent adding device, a spray foaming machine, a foaming agent adding method, and a foam manufacturing method that can prevent excessive foaming agent from being added to a liquid by providing a flow rate adjustment mechanism that adjusts the flow rate of the foaming agent in a flow path from a foaming agent container to an on-off valve that controls the amount of foaming agent added to the liquid. [Means for solving the problem]

[0007] The present invention is summarized as follows [1] to

[15] . [1] A foaming agent addition device for adding a foaming agent to a liquid supplied by a liquid pump and flowing through a liquid flow path, comprising: a liquid flow path pressure gauge for measuring the pressure of the liquid flowing through the liquid flow path; a pump operation detection unit for detecting the operation of the liquid pump; a foaming agent container for storing the foaming agent; a foaming agent flow path through which the foaming agent supplied from the foaming agent container flows; a foaming agent pressure gauge for measuring the pressure of the foaming agent flowing through the foaming agent flow path; a foaming agent pressure booster pump for pressurizing the foaming agent flowing through the foaming agent flow path so that the pressure of the foaming agent measured by the foaming agent pressure gauge is lower than the liquid pressure measured by the liquid flow path pressure gauge; a foaming agent metering pump for supplying a predetermined amount of the foaming agent to the liquid flow path; an on-off valve for controlling the addition of the foaming agent to the liquid by opening and closing; and a control unit for controlling the opening and closing of the on-off valve in accordance with the operation status of the liquid pump detected by the pump operation detection unit. [2] The foaming agent adding device according to [1], wherein the control unit opens the on-off valve when the drive position of the liquid pump reaches a predetermined position. [3] The foaming agent addition device according to [1] or [2], wherein the control unit controls the on-off valve to close when the predetermined amount of foaming agent has been added to the liquid. [4] The blowing agent adding device according to any one of [1] to [3], wherein the blowing agent metering pump is a positive displacement pump. [5] The blowing agent adding device according to any one of [1] to [4], wherein the blowing agent metering pump is a reciprocating pump. [6] The blowing agent adding device according to any one of [1] to [5], wherein the blowing agent pressure pump is a pump that continuously pressurizes the blowing agent. [7] The blowing agent adding device according to any one of [1] to [6], wherein the blowing agent pressure pump is either an axial pump or a gear pump. [8] The blowing agent adding device according to any one of [1] to [7], wherein the liquid contains a polyol or a polyisocyanate. [9] The blowing agent adding device according to any one of [1] to [8], wherein the liquid contains a filler.

[10] The blowing agent adding device according to any one of [1] to [9], wherein the blowing agent contains carbon dioxide.

[11] The foaming agent addition device according to any one of [1] to

[10] , wherein the control unit controls the on-off valve not to open when the liquid pressure measured by the liquid flow path pressure gauge is lower than a predetermined value.

[12] The blowing agent addition device according to any one of [1] to

[11] , further comprising a flow rate adjusting mechanism for adjusting the flow rate of the blowing agent in the blowing agent flow path upstream of the on-off valve.

[13] The blowing agent addition device according to

[12] , wherein the flow rate adjustment mechanism is a second on-off valve that controls the flow rate of the blowing agent flowing in the blowing agent flow path upstream of the on-off valve by opening and closing.

[14] A foam spray machine equipped with the foaming agent adding device according to any one of [1] to

[13] .

[15] A foaming agent adding method for adding a foaming agent to a liquid supplied by a liquid pump and flowing through a liquid flow path, comprising the steps of: supplying a foaming agent contained in a foaming agent container to a foaming agent flow path; measuring the pressure of the foaming agent flowing through the foaming agent flow path with a foaming agent pressure gauge; measuring the pressure of the liquid flowing through the liquid flow path with a liquid flow path pressure gauge; and adjusting the pressure of the foaming agent flowing through the foaming agent flow path so that the pressure of the foaming agent measured by the foaming agent pressure gauge is lower than the liquid pressure measured by the liquid flow path pressure gauge. a step of pressurizing the foaming agent to be supplied to the liquid flow path by a foaming agent pressurizing pump; a step of detecting the operation of the liquid pump by a pump operation detection unit; a step of metering a predetermined amount of the foaming agent to be supplied to the liquid flow path by a foaming agent metering pump; and a step of controlling the addition of the foaming agent to the liquid by opening and closing an on-off valve, wherein in the step of controlling the addition of the foaming agent by opening and closing an on-off valve, a control unit controls to open the on-off valve in accordance with the operation status of the liquid pump detected by the liquid pump operation detection unit.

[16] The foaming agent adding method according to

[15] , wherein in the step of controlling the addition of the foaming agent by opening and closing an on-off valve, when the pressure measured by the liquid pressure gauge is lower than a predetermined value, the on-off valve is controlled not to open.

[17] A method for producing a foam, comprising the step of adding a foaming agent to a liquid flowing through a liquid flow path by the method for adding a foaming agent according to

[15] or

[16] . [Effects of the Invention]

[0008] In the present invention, by controlling the blowing agent in accordance with the driving state of the liquid pump rather than the liquid pressure in the liquid flow path, it is possible to provide a blowing agent adding device, a spray foaming machine, a blowing agent adding method, and a foam manufacturing method that can stably supply a blowing agent to the liquid flowing through the liquid flow path without being affected by the pulsation of the liquid pump. Furthermore, the present invention can provide a foaming agent adding device, a foaming machine for spraying, a foaming agent adding method, and a foam manufacturing method that are capable of supplying a predetermined amount (predetermined volume) of foaming agent to a liquid flowing through a liquid flow path by utilizing a foaming agent metering pump that supplies a predetermined amount of foaming agent to a liquid flowing through a liquid flow path. Furthermore, the present invention can provide a foaming agent adding device, a foaming machine for spraying, a foaming agent adding method, and a foam manufacturing method that, when a foaming agent pressure pump is used, can reduce the burden on the foaming agent pressure pump, maintain the function of the foaming agent pressure pump, and stably supply the foaming agent. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a foaming agent adding device according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing a foam spraying machine according to a first embodiment of the present invention. [Figure 3] 1 is a flowchart showing a foaming agent addition method according to a first embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram (part 1) showing a foaming agent adding device according to a second embodiment of the present invention. [Figure 5] FIG. 2 is a schematic diagram (part 2) showing a foaming agent adding device according to a second embodiment of the present invention. [Figure 6] 1 is a flowchart (part 1) showing a method for adding a foaming agent according to a second embodiment of the present invention. [Figure 7] 10 is a flowchart (part 2) showing the foaming agent adding method according to the second embodiment of the present invention. [Figure 8] FIG. 10 is a schematic diagram showing a foaming agent adding device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The foaming agent adding device 10 according to the first embodiment is a device for mixing a foaming agent E into a liquid L1 flowing in a liquid flow path 30, as shown in FIG.

[0011] <Liquid> The liquid L1 is not particularly limited, but is preferably a foam raw material, which is a raw material for a foam. The blowing agent adding device 10 can produce a foam by mixing the foam raw material liquid L1 with a blowing agent E. Examples of foams include polyurethane foam, phenol foam, and polystyrene foam. Therefore, the liquid L1 can be any material that can be used as a raw material for these foams. Among the foams listed above, polyurethane foam is preferred from the viewpoints of ease of production, curing speed, and foamability. Furthermore, it is more preferable that the polyurethane foam is a rigid polyurethane foam. The use of a rigid polyurethane foam tends to improve self-adhesion, heat insulation, mechanical strength, and the like.

[0012] A urethane resin composition for forming polyurethane foam is generally prepared by mixing a first liquid containing a polyol with a second liquid containing a polyisocyanate. The urethane resin composition is foamed and cured by a blowing agent E mixed into the composition to form a polyurethane foam. The blowing agent E may be mixed into either the first liquid or the second liquid, but is preferably mixed into the first liquid from the standpoint of stability, etc. That is, the blowing agent adding device 10 preferably mixes the liquid blowing agent E into a liquid containing either a polyol or a polyisocyanate (first liquid or second liquid), but more preferably mixes the blowing agent E into a liquid containing a polyol (first liquid). The liquid (first liquid) containing the polyol is preferably a polyol composition containing a catalyst and a foam stabilizer in addition to the polyol, and may further contain a blowing agent. The blowing agent previously contained in the first liquid (polyol composition) in this way is also called an "internal blowing agent" to distinguish it from the above-mentioned blowing agent E.

[0013] The urethane resin composition for forming the polyurethane foam may contain a filler. When the urethane resin composition contains a filler, the flame retardancy of the resulting polyurethane foam is improved. It is preferable to mix the filler with a liquid (one-component or two-component) containing either a polyol or a polyisocyanate, but it is more preferable to mix the filler with a liquid (one-component) containing a polyol. The filler is contained as a solid component in the liquid raw material composition, and is generally a component present in the raw material composition in the form of particles or powder. The filler may be any component that is solid at room temperature (23° C.) and normal pressure (1 atmosphere) and does not dissolve in the liquid raw material composition. Examples of the filler include solid flame retardants and anti-settling agents. Examples of the solid flame retardant include red phosphorus-based flame retardants, boron-containing flame retardants, bromine-containing flame retardants, phosphate-containing flame retardants, chlorine-containing flame retardants, antimony-containing flame retardants, metal hydroxides, and needle-shaped fillers, and the solid flame retardant is preferably at least one selected from the group consisting of red phosphorus-based flame retardants, boron-containing flame retardants, and bromine-containing flame retardants.

[0014] In addition to the curing catalyst, foam stabilizer, and filler, the polyol composition may contain various additives such as a flame retardant (solid flame retardant, liquid flame retardant), an antioxidant, a heat stabilizer, a metal inhibitor, an antistatic agent, a crosslinking agent, a lubricant, a softener, and a pigment.

[0015] <Foaming agent> The internal blowing agent is not particularly limited, and examples thereof include hydrofluoroolefins (HFOs), hydrofluorocarbons (HFCs), hydrocarbons, and diethyl ether. Examples of the hydrofluoroolefins (HFOs) used as internal blowing agents include fluoroalkenes having approximately 3 to 6 carbon atoms, preferably 3 or 4 carbon atoms, and more preferably 3 carbon atoms. The hydrofluoroolefins may be hydrochlorofluoroolefins having chlorine atoms. Examples of hydrofluorocarbons (HFCs) include hydrofluorocarbons having approximately 1 to 4 carbon atoms, and the hydrofluorocarbons may have chlorine atoms. Examples of hydrocarbons include hydrocarbons having 2 to 5 carbon atoms. As hydrocarbons having 2 to 5 carbon atoms, hydrocarbons having 3 or 4 carbon atoms are preferred, and LPG containing propane and butanes as main components can also be used.

[0016] On the other hand, the blowing agent E may be any blowing agent that can be used for foaming using the froth method, and may be a blowing agent that becomes a gas at room temperature (23°C) and normal pressure (1 atm), preferably one with a boiling point of less than 0°C at normal pressure. The blowing agent E is not particularly limited, but examples include hydrofluoroolefin (HFO) and carbon dioxide. The froth method involves mixing blowing agent E, which becomes a gas at room temperature and normal pressure, with a foam raw material such as a liquid (one-component) containing polyol to foam the mixture. The liquid containing polyol may already contain a blowing agent (internal blowing agent), and in such cases, blowing agent E functions as a foaming assistant to improve foamability and workability.

[0017] In the present invention, it is preferable to use carbon dioxide as the blowing agent E. Carbon dioxide can be mixed into the liquid L1 in a liquid state by pressurization, as described below, thereby improving its miscibility with the liquid L1. Furthermore, the use of carbon dioxide reduces the environmental impact. However, carbon dioxide may be mixed into the liquid L1 in a supercritical or subcritical state. When carbon dioxide is used as the blowing agent E, carbon dioxide may be used alone, or a mixed gas of hydrofluoroolefin (HFO) and carbon dioxide may be used.

[0018] (Foaming agent adding device) The blowing agent addition device 10 will now be described in more detail. The foaming agent addition device 10 includes a liquid flow path pressure gauge 31, a pump operation detection unit 41, a foaming agent container 11, a foaming agent flow path 12, a foaming agent pressure gauge 81, a foaming agent pressure pump 80, a foaming agent metering pump 50, an on-off valve 60, and a control unit 61. The foaming agent addition device 10 is a device for adding a foaming agent E to a liquid L flowing through the liquid flow path 30.

[0019] A liquid pump 40 is connected to the liquid flow path 30, and the liquid L1 filled in a container (not shown) such as a drum can is supplied to the liquid flow path 30 by the liquid pump 40 and delivered therefrom. The liquid pump 40 may be either a positive displacement or non-positive displacement pump, but is preferably a positive displacement pump. Positive displacement pumps have large pulsations, but the present invention makes it possible to stably supply the foaming agent even with large pulsations. The positive displacement pump may be either a reciprocating or rotary pump, but reciprocating pumps such as syringe pumps with a sealing mechanism on the drive side and plunger pumps with a sealing mechanism on the cylinder side are preferred. The positive displacement pump may also be a variable displacement or fixed displacement pump. Depending on the type of pump, liquid pump 40 periodically drives various drive parts such as a cylinder, gear, vane, and plunger by rotational or linear motion to repeatedly discharge fluid. For example, in a syringe pump, the cylinder repeatedly moves linearly between the bottom dead center and the top dead center.

[0020] The liquid L1 that flows through the liquid flow path 30 is pressurized to the discharge pressure. A liquid flow path pressure gauge 31 is connected to the liquid flow path 30, and the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 is measured by the liquid flow path pressure gauge 31. From the viewpoint of operational stability, the pressure LP of the liquid L1 flowing through the liquid flow path 30 is preferably 5 to 10 MPa. The liquid flow path pressure gauge 31 transmits the measured liquid pressure LP to the control unit 61.

[0021] The liquid pump 40 is provided with a pump drive detection unit 41. The pump drive detection unit 41 detects the drive of the liquid pump 40. The pump drive detection unit 41 transmits pump drive information DI relating to the detected drive of the liquid pump 40 to the control unit 61. As described above, liquid pump 40 periodically drives the drive unit by reciprocating or rotating motion, and pump drive detector 41 can detect the position to which the drive unit is driven during that period. For example, a reciprocating pump such as a syringe pump reciprocates between bottom dead center and top dead center, and pump drive detector 41 can detect the position to which the pump's drive unit is driven during that reciprocating motion. Similarly, with a rotary pump, it is sufficient to detect the position to which the drive unit is driven during rotational motion. A sensor is used as pump drive detection unit 41. Specific examples of the sensor include a laser distance sensor that measures the drive position of the drive unit of liquid pump 40 as a distance, and a position sensor that detects that the drive unit of liquid pump 40 has reached a certain position (for example, top dead center or bottom dead center).

[0022] A pressure-resistant container, such as a known gas cylinder, is used as the foaming agent container 11. The foaming agent container 11 preferably stores the foaming agent E in a pressurized state. The foaming agent container 11 may also be equipped with a heater (not shown). By heating the foaming agent container 11 with the heater, the internal pressure of the foaming agent container 11 increases, thereby reducing the pressure load imposed by the foaming agent pressure pump 80 and making it easier to deliver the foaming agent E to the foam flow path 12 in a pressurized state.

[0023] As described above, the foaming agent flow path 12 is a path for supplying the foaming agent E from the foaming agent container 11 to the liquid flow path 30. The foaming agent flow path 12 may be equipped with a flow path cooling device (not shown) made up of a coolant or the like, thereby cooling the foaming agent E flowing through the foaming agent flow path 12. By cooling the foaming agent E in the foaming agent flow path 12, the foaming agent E becomes less likely to vaporize in each foaming agent flow path, making it easier to mix the foaming agent E in a liquid state with the liquid L. The temperature inside the foaming agent flow path 12 is preferably maintained in the range of -20 to 20°C.

[0024] A foaming agent pressure gauge 81 is provided in the foaming agent passage 12. The foaming agent pressure gauge 81 measures the foaming agent pressure EP of the foaming agent E flowing through the foaming agent passage 12. The foaming agent passage pressure gauge 81 transmits the measured foaming agent pressure EP to the control unit 61.

[0025] A foaming agent pressure pump 80 is provided in the foaming agent flow path 12. The foaming agent pressure pump 80 is connected to the control unit 61 and is provided upstream of the foaming agent metering pump 50 in the foaming agent flow path 12. The foaming agent pressure pump 80 increases the foaming agent pressure EP of the foaming agent E flowing through the foaming agent flow path 12 to a pressure lower than the pressure LP of the liquid L1 flowing through the liquid flow path 30, thereby reducing the burden on the foaming agent pressure pump and making it easier to maintain the function of the foaming agent pressure pump. The blowing agent pressure EP of the blowing agent E flowing through the blowing agent flow path 12 is preferably lower than the pressure LP of the liquid L1 flowing through the liquid flow path 30 by 0.1 to 3 MPa or more, from the viewpoint of preventing an excessive amount of blowing agent E from being added to the liquid flow path 30. From the viewpoint of being able to supply the blowing agent E to the blowing agent metering pump 50 at a constant rate, the blowing agent pressure pump 80 is preferably a pump that can pressurize and supply the blowing agent E at a stable pressure, more preferably a pump that can continuously pressurize the blowing agent, and among these, it is preferably either an axial pump or a gear pump. The blowing agent pressure EP inside the blowing agent flow path 12 is prone to change, such as decreasing due to the suction of the blowing agent metering pump 50, and changes in the blowing agent pressure EP can cause the blowing agent E to vaporize or flow back. Therefore, it is preferable to adjust the blowing agent pressure EP of the blowing agent E sent to the liquid flow path 30 and the blowing agent metering pump 50 to be in the range of 5 to 12 MPa. By adjusting the blowing agent E in the blowing agent flow path 12 to be within the above range, it is easier to supply the blowing agent E in a liquid state to the liquid flow path 30. When the blowing agent E is supplied to the liquid flow path 30 in a liquid state, it is easier to mix with the liquid L1.

[0026] The blowing agent pressure pump 80 may be controlled by the control unit 61. The control unit 61 compares the liquid pressure LP received from the liquid flow path pressure gauge 31 with the blowing agent pressure EP received from the blowing agent pressure gauge 81, and controls the blowing agent pressure pump 80 to increase the blowing agent pressure EP of the blowing agent E flowing through the blowing agent flow path 12 to a pressure lower than the pressure LP of the liquid L1 flowing through the liquid flow path 30. When the blowing agent pressure EP is less than a predetermined pressure, the control unit 61 controls the blowing agent pressure pump 80 to continue supplying the blowing agent E to the blowing agent metering pump 50. When the blowing agent pressure EP reaches a predetermined pressure, the control unit 61 may also control the blowing agent pressure pump 80 to stop supplying the blowing agent E to the blowing agent metering pump 50. As described above, by controlling the blowing agent pressure EP of the blowing agent E, it is possible to stably supply the blowing agent E to the blowing agent metering pump 50 provided downstream.

[0027] A foaming agent metering pump 50 is provided in the foaming agent flow path 12. The foaming agent metering pump 50 receives and meters the foaming agent E flowing through the foaming agent flow path 12, thereby supplying a predetermined amount (predetermined volume) of foaming agent E to the liquid flow path 30. By providing the foaming agent metering pump 50, even if the foaming agent pressure EP of the foaming agent E flowing through the foaming agent flow path 12 is lower than the liquid pressure LP, the discharge pressure of the foaming agent E supplied to the liquid flow path 30 can be made higher than or equal to the pressure of the liquid L1 flowing through the liquid flow path 30, due to the discharge pressure generated by the driving force of the foaming agent metering pump, and backflow of the liquid L1 can be prevented. The foaming agent metering pump 50 may be either a non-positive displacement or a positive displacement pump, but a positive displacement pump is preferred because it is easy to supply a constant amount of foaming agent and to vary the volume. As a positive displacement pump, a reciprocating pump such as a syringe pump or a plunger pump is preferred, and among them, a syringe pump is preferred because it has high metering accuracy for one shot amount and is also excellent for high-pressure transport. Furthermore, by using a positive displacement pump, particularly a syringe pump, even if the foaming agent pressure EP of the foaming agent E flowing through the foaming agent flow path 12 is lower than the liquid pressure LP, the foaming agent E can be pressurized by the foaming agent metering pump 50, and the pressure at which the foaming agent E is supplied to the liquid flow path 30 can be made higher than the pressure LP of the liquid L1 flowing through the liquid flow path 30. The blowing agent metering pump 50 may be of a variable displacement type or a fixed displacement type, but a variable displacement type is preferred. By varying the volume, it is possible to vary the predetermined amount of blowing agent E to be supplied. The volume variable control of the blowing agent metering pump 50 may be implemented by a known control device equipped with a CPU (microprocessor), memory, input ports, output ports, etc., and may be implemented by a personal computer or may be manually variable.

[0028] An on-off valve 60 is provided in the foaming agent flow path 12 downstream of the foaming agent metering pump 50. The on-off valve 60 controls the addition of the foaming agent E to the liquid L1 by opening and closing. When the on-off valve 60 is opened, the foaming agent E flowing through the foaming agent flow path 12 is supplied to the liquid L1. When the on-off valve 60 is closed, the supply of the foaming agent E to the liquid L1 is stopped. The on-off valve 60 is configured, for example, by a solenoid valve.

[0029] A control unit 61 that controls the opening and closing of the on-off valve 60 is connected to the on-off valve 60. The control unit 61 receives pump drive information DI of the liquid pump 40 from the pump drive detection unit 41, and controls the on-off valve 60 to open in accordance with the drive status of the liquid pump 40. Specifically, the control unit 61 controls the on-off valve 60 to open when the drive position of the liquid pump 40 reaches a predetermined position (predetermined position). When the on-off valve 60 is opened, a predetermined amount of foaming agent E is supplied to the liquid flow path 30, as described above. As described above, the liquid pump 40 is driven periodically, and when the position (drive position) of the drive unit of the liquid pump 40 reaches a predetermined position and the on-off valve 60 opens, the foaming agent E is supplied to the liquid L1 at the same timing in that period. Here, the liquid pump 40 supplies the liquid L to the flow path 30 with approximately the same behavior (i.e., approximately the same pressure and the same flow rate) at the same timing in the period, so when a predetermined amount (i.e., a constant amount) of foaming agent is supplied to the flow path 30 at that timing, the supply of the foaming agent E to the liquid L1 becomes stable. In other words, in this embodiment, rather than controlling according to the liquid pressure in the liquid flow path 30, the opening / closing valve 60 is controlled to open when the drive part of the liquid pump 40 reaches a predetermined position (specified position), thereby enabling a stable supply of foaming agent E to the liquid L1. Furthermore, by controlling the on-off valve 60 to open when the predetermined position is reached and then to close, the on-off valve is repeatedly opened and closed.

[0030] The predetermined position is not particularly limited, but when the liquid pump 40 is a reciprocating pump such as a syringe pump, it may be the top dead center, the bottom dead center, or a specific position between these, but is preferably either the top dead center or the bottom dead center. When the top dead center or the bottom dead center is reached, the pressure of the liquid L1 supplied to the liquid flow path 30 thereafter decreases. Therefore, if the predetermined position is the top dead center or the bottom dead center, the foaming agent E will be supplied at the timing when the pressure decreases, making it easier to mix the foaming agent E with the liquid L1. Furthermore, in a reciprocating pump, the predetermined position does not have to be one location during one cycle in which the drive unit moves from top dead center to bottom dead center and then moves from bottom dead center to top dead center, but may be two or more locations; for example, both the top dead center and the bottom dead center may be set as predetermined positions. In addition, in the case of a rotary pump, the predetermined position may be set to, for example, a specific position n° (where n is any position from 0 to 360) within the rotation period (0 to 360°).

[0031] The control unit 61 may control the on-off valve 60 to open once per cycle of the drive unit of the liquid pump 40, or may control the on-off valve 60 to open once per two cycles, or may control the on-off valve 60 to open once per n cycles (n is an integer of 3 or more). The control unit 61 may also control the on-off valve 60 to open multiple times per cycle of the drive unit of the liquid pump 40, for example, to open once per half cycle. Note that opening the valve once per cycle means, for example, that if the top dead center is set to a predetermined position, the valve opens every time the top dead center is reached. The same applies to the bottom dead center. Furthermore, for example, if the predetermined position is a specific position between top dead center and bottom dead center, there is no need to open the on-off valve 60 in any case where the drive unit is at the predetermined position, and it is preferable to control the valve to open either when the drive unit moves from top dead center to bottom dead center or from bottom dead center to top dead center. Furthermore, in a double-acting pump having multiple drive units (for example, a double-acting plunger pump), the on-off valve may be controlled based on the drive of any one of the drive units, or may be controlled based on the drive of multiple drive units. When controlled based on the drive of multiple drive units, for example, the valve may be opened each time the drive unit of each drive unit is positioned at a predetermined position.

[0032] The control unit 61 controls the on-off valve 60 to close when a predetermined amount of foaming agent E has been added from the foaming agent metering pump 50 to the liquid L1 in the liquid flow path 30. By closing the on-off valve 60 when a predetermined amount of foaming agent E has been added from the foaming agent metering pump 50 to the liquid L1 in the liquid flow path 30 in this way, it is possible to stably supply a predetermined amount (predetermined volume) of foaming agent E without adding excess foaming agent E to the liquid L1 flowing through the liquid flow path 30. Here, the control unit 61 may measure the amount of foaming agent E delivered from the foaming agent metering pump 50, and when the delivered amount reaches a specified amount, determine that a predetermined amount of foaming agent E has been added to the liquid L1 and close the valve, or may close the valve after a certain time has passed since the valve was opened, thereby adding a predetermined amount of foaming agent E to the liquid L1. Furthermore, the control unit 61 may detect the operation of the foaming agent metering pump 50, and close the valve when it determines that the predetermined amount of foaming agent E metered by the foaming agent metering pump 50 has been added in its entirety.

[0033] The control unit 61 also receives the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 measured by the liquid flow path pressure gauge 31, and controls the on-off valve 60 not to open when the measured pressure LP is lower than a predetermined value. By controlling the on-off valve 60 not to open when the measured pressure LP is lower than the predetermined value, the addition of the foaming agent E can be prevented when the amount of liquid L1 flowing through the liquid flow path 30 is small. Examples of when the measured pressure LP is lower than the predetermined value include when the foaming agent addition device 10 is started up or stopped, and when the liquid flow path 30 is clogged. The predetermined value of the measured pressure LP is preferably lower than the pulsating fluctuation of the liquid pump 40, and may be set to, for example, 3 MPa.

[0034] The control unit 61 also receives the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 measured by the liquid flow path pressure gauge 31 and the blowing agent pressure EP of the blowing agent E flowing through the blowing agent flow path 12 measured by the blowing agent flow path pressure gauge 81, and controls the blowing agent pressure pump 80 so that the blowing agent pressure EP is lower than the liquid pressure LP.

[0035] The amount of blowing agent E supplied to the liquid L1 flowing through the liquid flow channels 30 is preferably 0.05 to 5.0%, more preferably 0.1 to 4.5%, and even more preferably 0.15 to 4.0%, in terms of volume ratio when blowing agent E is added to liquid L1. By keeping the amount of blowing agent E supplied within the above range, it becomes possible to incorporate an appropriate amount of blowing agent into polyol, etc., and to appropriately foam the polyurethane foam. The amount of blowing agent E supplied to the liquid L1 flowing through the liquid flow channels 30 is preferably adjusted depending on the blowing agent E used. For example, if the blowing agent E is carbon dioxide, the amount is preferably 0.2 to 2.0%, and if the blowing agent E is a mixed gas of hydrofluoroolefin and carbon dioxide, the amount is preferably 0.4 to 3.5%.

[0036] (Spray foaming machine) As shown in FIG. 2, the spray foaming machine 1 is equipped with the above-described blowing agent adding device 10. The spray foaming machine 1 in this embodiment is a device for forming polyurethane foam. However, the spray foaming machine in the present invention is not limited to a device for forming polyurethane foam, and may be a device for forming other foams. As described above, the polyurethane foam is preferably a rigid polyurethane foam. Furthermore, the spray foaming machine 1 is an on-site spray foaming machine, and is a device that is brought to a construction site where polyurethane foam is to be applied and forms polyurethane foam at the construction site.

[0037] The spray foaming machine 1 further comprises the above-mentioned liquid flow path 30 (hereinafter also referred to as the first liquid flow path 30) and liquid pump 40 (hereinafter also referred to as the first liquid pump 40) in addition to the blowing agent adding device 10. The spray foaming machine 1 also comprises a second liquid flow path 32 through which a liquid L2 separate from the above-mentioned liquid L1 flows, and a liquid pump 42 (hereinafter also referred to as the second liquid pump 42) that delivers the liquid L2 to the second liquid flow path 32. The first and second liquid pumps 40, 42 are connected to a liquid container (not shown) such as a drum, and deliver the liquids L1, L2 sucked from the liquid container to the first and second liquid flow paths 30, 32, respectively.

[0038] As described above, polyurethane foam can be formed by mixing a first liquid containing a polyol and a second liquid containing a polyisocyanate, followed by foaming and curing. Liquid L1 flowed through first liquid flow path 30 is one of the first liquid or the second liquid, and liquid L2 flowed through second liquid flow path 32 is the other of the first liquid or the second liquid. However, it is preferable that liquid L1 is the first liquid containing a polyol and liquid L2 is the second liquid containing a polyisocyanate.

[0039] The spray foaming machine 1 includes a spray gun 70. The spray gun 70 includes a discharge section 70A and a mixing section 70B. The first and second liquid flow paths 30, 35 merge in the mixing section 70B. The first and second liquids flowing through the first and second liquid flow paths 30, 32 are mixed in the mixing section 70B, and the resulting mixture (urethane resin composition) is sprayed from the discharge section 70A. In this case, the urethane resin composition may be sprayed onto the target surface, such as the roof, wall, or floor of a building or structure. The sprayed urethane resin composition foams and hardens to become polyurethane foam. The polyurethane foam is used, for example, as a heat insulating material.

[0040] In the above-described spray foaming machine 1, liquid L1, which is appropriately mixed with foaming agent E using the foaming agent adding device 10, is used as a raw material for polyurethane foam, so that polyurethane foam with good foamability and sprayability can be formed.

[0041] [How to add foaming agent] A method for adding the foaming agent E to the liquid L1 in the foaming agent adding device 10 in this embodiment will be described in detail with reference to the flowchart in Fig. 3. Note that the following describes the pressure, temperature, etc., taking the case where the foaming agent E is carbon dioxide as a specific example, but when the foaming agent E is another substance, the pressure, temperature, etc. may be set according to the properties of that substance.

[0042] In step S1, the blowing agent E contained in the blowing agent container 11 is supplied to the blowing agent passage 12. The temperature of the blowing agent E supplied to the blowing agent passage 12 is preferably maintained in the range of -20 to 20°C. The pressure inside the blowing agent passage 12 is preferably adjusted so that the pressure of the blowing agent E sent to the blowing agent metering pump 50 is in the range of 5 to 12 MPa.

[0043] Next, in step S2, the blowing agent pressure EP of the blowing agent E flowing through the blowing agent passage 12 is measured by the blowing agent pressure gauge 81. The obtained blowing agent pressure EP is sent to the control unit 61.

[0044] In step S3, the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 is measured by the liquid pressure gauge 31. The obtained liquid pressure LP is sent to the control unit 61.

[0045] Next, in step S4, the blowing agent E flowing through the blowing agent flow path 12 is pressurized by the blowing agent pressure pump 80 so that the blowing agent pressure EP of the blowing agent E measured by the blowing agent pressure gauge 81 is lower than the liquid pressure LP measured by the liquid flow path pressure gauge 31. Specifically, the control unit 61 receives the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 measured by the liquid flow path pressure gauge 31 and the blowing agent pressure EP of the blowing agent E flowing through the blowing agent flow path 12 measured by the blowing agent flow path pressure gauge 81, compares the liquid pressure LP and the blowing agent pressure EP, and controls the blowing agent pressure pump 80 so that the blowing agent pressure EP is lower than the liquid pressure LP.

[0046] Next, in step S5, the operation of the liquid pump 40 is detected by the pump operation detection unit 41. Specifically, the pump operation detection unit 41 detects the operation position of the drive unit of the liquid pump 40, which pressurizes the liquid L1 flowing through the liquid flow path 30, and obtains pump operation information DI related to the detected operation of the liquid pump 40. The pump operation detection unit 41 is preferably a laser appliqué sensor that can continuously measure the operation position of the drive unit of the liquid pump 40. The obtained pump operation information DI is sent to the control unit 61.

[0047] Next, in step S6, a predetermined amount of foaming agent E to be supplied to the liquid flow path 30 is metered by the foaming agent metering pump 50.

[0048] Next, in step S7, the addition of the foaming agent E to the liquid L1 is controlled by opening and closing the on-off valve 60. In the process of controlling the addition of foaming agent E by opening and closing on-off valve 60, control unit 61 controls to open on-off valve 60 in accordance with the driving status of liquid pump 40 detected by pump drive detection unit 41. Specifically, control unit 61 receives pump drive information DI of liquid pump 40 from pump drive detection unit 41, and controls to open on-off valve 60 when the driving position of the drive unit in liquid pump 40 reaches a predetermined position (predetermined position).

[0049] However, the above steps S1 to S7 merely show one example of control, and may be performed in any order as long as it does not deviate from the gist of the present invention. For example, step S2 may be performed simultaneously in parallel with each of steps S3 to S6, or may be performed after any of steps S3 to S6. For example, step S5 and step S6 may be performed in reverse order, or may be performed simultaneously in parallel. Furthermore, steps S2 to S4 and steps S5 to S6 may also be performed simultaneously in parallel. Step S2 and step S3 may also be performed in reverse order, or may be performed simultaneously in parallel.

[0050] [Foam manufacturing method] A foam can be formed by using the blowing agent addition apparatus 10 according to the first embodiment of the present invention. The method for producing a polyurethane foam in this embodiment includes the above steps S1 to S7, and further includes a step of adding blowing agent E to liquid L1 flowing through liquid flow path 30 in the blowing agent addition apparatus 10, mixing the liquid L1 and liquid L2 in the spray foaming machine 1 to prepare a mixture, and discharging the mixture from the discharge device. Specifically, the method includes the following steps (1) to (8). (1) Step of supplying the foaming agent E contained in the foaming agent container 11 to the foaming agent flow path 12 (2) A step of measuring the liquid pressure LP of the liquid L1 flowing through the liquid flow path 30 with a liquid pressure gauge 31. (3) A step of measuring the blowing agent pressure EP of the blowing agent E flowing through the blowing agent flow path 12 with a blowing agent pressure gauge 81. (4) A step of pressurizing the blowing agent E flowing through the blowing agent flow path 12 with the blowing agent pressure pump 80 so that the blowing agent pressure EP of the blowing agent E measured by the blowing agent pressure gauge 81 is lower than the liquid pressure LP measured by the liquid flow path pressure gauge 31. (5) A step of detecting the operation of the liquid pump 40 by the pump operation detection unit 41 (6) A step of measuring a predetermined amount of foaming agent E to be supplied to the liquid flow path 30 by the foaming agent metering pump 50. (7) A step of controlling the addition of the foaming agent E to the liquid L1 by opening and closing the on-off valve 60. (8) A step of adding a foaming agent E to the liquid L1 flowing through the liquid flow path 30 in the foaming agent adding device 10, mixing the liquid L1 and the liquid L2 in the foam spraying machine 1, and discharging the mixture from the discharging device.

[0051] As described above, in this embodiment, by providing pump drive detection unit 41 that detects the drive of liquid pump 40, the drive status of liquid pump 40 is detected and control is performed in accordance with the drive status of liquid pump 40. In this way, by performing control in accordance with the drive status of liquid pump 40 rather than control in accordance with the liquid pressure within liquid flow path 30, foaming agent E can be stably supplied to liquid L1 flowing through liquid flow path 30 without being affected by pulsation of liquid pump 40. In addition, in this embodiment, by using the foaming agent metering pump 50 that supplies a predetermined amount of foaming agent E to the liquid L1 flowing through the liquid flow path 30, a predetermined amount (predetermined volume) of foaming agent can be stably supplied to the liquid L1 flowing through the liquid flow path 30. Furthermore, in this embodiment, by utilizing the foaming agent pressure pump 80, the foaming agent pressure EP in the foaming agent passage 12 is maintained lower than the liquid pressure LP in the liquid passage 30, thereby reducing the burden on the foaming agent pressure pump 80, maintaining the function of the foaming agent pressure pump 80, and enabling a stable supply of the foaming agent.

[0052] [Second embodiment] Next, a second embodiment of the present invention will be described in detail. The second embodiment differs from the first embodiment in that, as shown in FIGS. 4 and 5, a flow rate adjusting mechanism 90 for adjusting the flow rate of the foaming agent E is provided in the foaming agent flow path 12 upstream of the on-off valve 60. Differences between the first embodiment and the second embodiment will be described below. Parts for which description will be omitted are the same as those in the first embodiment. In the following description, members having the same configuration as those in the first embodiment will be denoted by the same reference numerals.

[0053] As shown in FIG. 4, the flow rate adjustment mechanism 90 may be provided in the blowing agent flow path 12 that is upstream of the on-off valve 60 and downstream of the blowing agent pressure pump 80, or as shown in FIG. 5, the flow rate adjustment mechanism 90 may be provided in the blowing agent flow path 12 that is upstream of the on-off valve 60 and upstream of the blowing agent pressure pump 80. The flow rate adjustment mechanism 90 adjusts the flow rate of the blowing agent E to the blowing agent metering pump 50. The flow rate adjustment mechanism 90 may be a second on-off valve that controls the flow rate of the blowing agent E flowing in the blowing agent flow path 12 upstream of the on-off valve 60 by opening or closing the second on-off valve. The flow rate adjustment mechanism 90 supplies the blowing agent E flowing in the blowing agent flow path 12 to the blowing agent metering pump 50 by opening the second on-off valve. On the other hand, the flow rate adjustment mechanism 90 stops the supply of the blowing agent E to the blowing agent metering pump 50 by closing the second on-off valve. The second on-off valve may be, for example, a solenoid valve. The flow rate adjusting mechanism 90 is preferably located closer to the on-off valve 60, which allows for stable control, and the configuration shown in FIG. 4 is preferable.

[0054] An on-off valve control unit 61 that controls the opening or closing of the second on-off valve is connected to the flow rate adjustment mechanism 90. The on-off valve control unit 61 controls the flow rate adjustment mechanism (second on-off valve) 90 depending on the open / closed state of the on-off valve 60. Specifically, when the on-off valve 60 is open, the flow rate adjustment mechanism 90 is closed. Furthermore, when the on-off valve 60 is closed, the flow rate adjustment mechanism 90 is opened to supply the blowing agent to the blowing agent metering pump 50, and then the flow rate adjustment mechanism 90 is closed before the on-off valve 60 is switched back to open or at the same time as the on-off valve 60 is switched to open. In this way, by controlling the opening and closing state of the flow rate adjustment mechanism 90, it is possible to control the flow path from the blowing agent container 11 to the on-off valve 60 to be prevented from being directly connected. In other words, by controlling the flow rate adjustment mechanism 90 to be prevented from being directly connected to the flow path from the blowing agent container 11 to the on-off valve 60, it is possible to prevent the blowing agent E from being added excessively to the liquid L1 from the blowing agent container 11, even if the blowing agent pressure in the blowing agent container 11 becomes high.

[0055] The method of adding the foaming agent E to the liquid L1 in the foaming agent adding device 10 shown in FIG. 4 of this embodiment is shown in the flowchart of FIG. 6, and the method of adding the foaming agent E to the liquid L1 in the foaming agent adding device 10 shown in FIG. 5 is shown in the flowchart of FIG. 7. 6, the process includes a step (step S10) of closing the on-off valve 60 and opening the flow rate adjusting mechanism 90 before the step (step S6) of metering the blowing agent E by the blowing agent metering pump 80. Then, the process includes a step (step S11) of closing the flow rate adjusting mechanism 90 before the step (step S7) of controlling the addition of the blowing agent E by opening and closing the on-off valve 60. 7 includes a step (step S10) of closing the on-off valve 60 and opening the flow rate adjustment mechanism 90 before a step (step S1) of supplying the foaming agent E contained in the foaming agent container 11 to the foaming agent flow path 12. Also, includes a step (step S11) of closing the flow rate adjustment mechanism 90 before a step (step S7) of controlling the addition of the foaming agent E by opening and closing the on-off valve 60.

[0056] However, the steps shown in the flowcharts of Figures 6 and 7 are merely examples of control, and may be performed in any order as long as it does not deviate from the gist of the present invention. For example, step S2 may be performed simultaneously in parallel with steps S3 to S6 and steps S10 and S11, or may be performed after any of steps S3 to S6 and steps S10 and S11. For example, steps S5 and S6 may be performed in reverse order or may be performed simultaneously in parallel. Furthermore, steps S2 to S4 and steps S5 to S6 may also be performed simultaneously in parallel. Steps S2 and S3 may also be performed in reverse order or may be performed simultaneously in parallel.

[0057] As described above, in this embodiment, by providing the flow rate adjustment mechanism 90, it is possible to control the connection of the flow path from the foaming agent container 11 to the on-off valve 60, and even when the foaming agent container 11 is pressurized, it is possible to adjust the differential pressure between the foaming agent E and the liquid pressure in the liquid flow path 30. By adjusting the differential pressure between the foaming agent E and the liquid pressure in the liquid flow path 30, the foaming agent metering pump 50 can stably supply a predetermined amount (predetermined volume) of foaming agent to the liquid L1 flowing through the liquid flow path 30. Note that, although an example has been described in which the flow rate adjustment mechanism 90 in this embodiment is the second on-off valve, other mechanisms may be used as long as they are capable of adjusting the flow rate of the foaming agent E.

[0058] [Other embodiments] The foaming agent adding device, the spray foaming machine, the foaming agent adding method, and the foam manufacturing method described above using the first and second embodiments are merely examples of the present invention, and the present invention is not limited to the configurations of the above embodiments. Various improvements and modifications are possible within the scope of the present invention, and components may be added as appropriate. For example, before the step (step S6) of metering a predetermined amount of foaming agent E to be supplied to the liquid flow path 30 using the foaming agent metering pump 50, a step of pressurizing the foaming agent E flowing through the foaming agent flow path 12 to a predetermined pressure using the foaming agent pressure pump 80 is included. In the step of pressurizing the foaming agent E to a predetermined pressure by the foaming agent pressure pump 80, the pressure of the foaming agent E flowing through the foaming agent flow path 12 may be measured by a foaming agent pressure gauge 81 provided between the foaming agent pressure pump 80 and the foaming agent metering pump 50. By measuring the pressure by the foaming agent pressure gauge 81, the accuracy of pressurizing the foaming agent E to a predetermined pressure by the foaming agent pressure pump 80 can be improved, and the foaming agent E can be supplied more stably to the foaming agent metering pump 50 provided downstream.

[0059] For example, in the foaming agent addition method, in the step (step S7) of controlling the addition of foaming agent E to liquid L1 by opening and closing on-off valve 60, if the measured pressure LP of liquid pressure gauge 31 is lower than a predetermined value, control may be performed so that on-off valve 60 does not open. By including step S20 in the foaming agent addition method, when the amount of liquid L1 flowing through liquid flow path 30 is small, such as when foaming agent addition device 10 is started or stopped, or when liquid flow path 30 is clogged, foaming agent E is not added at a stable rate, so control can be performed to prevent addition. The predetermined value of measured pressure LP is preferably a value lower than the pulsation fluctuation of liquid pump 40, and may be set to, for example, 3 MPa.

[0060] For example, as shown in FIG. 8, the blowing agent adding device 10 can be configured to include a check valve 62 between the blowing agent metering pump 50 and the on-off valve 60 to prevent backflow of the blowing agent E flowing through the blowing agent flow path 12. [Explanation of symbols]

[0061] 1. Spray foaming machine 10. Foaming agent adding device 11 Foaming agent container 12. Foaming agent flow path 30 liquid flow path (first liquid flow path) 31 Liquid flow path pressure gauge 32 second liquid flow path 40 Liquid pump (first liquid pump) 41 Pump drive detection unit 41 42 Liquid pump (second liquid pump) 50 Foaming agent metering pump 60 On-off valve 61 Control Unit 62 Check valve 70 spray gun 70A discharge part 70B Mixing section 80 Foaming agent pressure pump 81 Foaming agent pressure gauge 90 Flow rate adjustment mechanism E. Foaming Agent L1, L2 liquid

Claims

1. A foaming agent adding device for adding a foaming agent to a liquid supplied by a liquid pump and flowing through a liquid flow path, comprising: a liquid flow path pressure gauge that measures the pressure of the liquid flowing through the liquid flow path; a pump operation detection unit that detects operation of the liquid pump; a foaming agent container for containing the foaming agent; a foaming agent flow path through which the foaming agent supplied from the foaming agent container flows; a blowing agent pressure gauge for measuring the pressure of the blowing agent flowing through the blowing agent flow path; a blowing agent pressure pump that pressurizes the blowing agent flowing through the blowing agent flow path so that the pressure of the blowing agent measured by the blowing agent pressure gauge is lower than the pressure of the liquid measured by the liquid flow path pressure gauge; a blowing agent metering pump that receives the blowing agent flowing through the blowing agent flow path without receiving the liquid flowing through the liquid flow path, and meters the blowing agent to supply a predetermined amount of the blowing agent to the liquid flow path; an on-off valve that controls the addition of the foaming agent to the liquid by opening and closing; a control unit that controls the opening and closing valve in accordance with the driving state of the liquid pump detected by the pump driving detection unit.

2. 2. The foaming agent adding device according to claim 1, wherein the control unit opens the on-off valve when the drive position of the liquid pump reaches a predetermined position.

3. 3. The foaming agent adding device according to claim 1, wherein the control unit controls the on-off valve to close when the predetermined amount of the foaming agent has been added to the liquid.

4. 4. The blowing agent adding device according to claim 1, wherein the blowing agent metering pump is a positive displacement pump.

5. 5. The blowing agent adding device according to claim 1, wherein the blowing agent metering pump is a reciprocating pump.

6. 6. The blowing agent adding device according to claim 1, wherein the blowing agent pressurizing pump is a pump that continuously pressurizes the blowing agent.

7. 7. The blowing agent adding device according to claim 1, wherein the blowing agent pressure pump is either an axial pump or a gear pump.

8. The blowing agent adding device according to any one of claims 1 to 7, wherein the liquid includes a polyol or a polyisocyanate.

9. The foaming agent adding device according to any one of claims 1 to 8, wherein the liquid contains a filler.

10. The blowing agent adding device according to any one of claims 1 to 9, wherein the blowing agent includes carbon dioxide.

11. The foaming agent addition device according to any one of claims 1 to 10, wherein the control unit controls the on-off valve not to open when the pressure of the liquid measured by the liquid flow path pressure meter is lower than a predetermined value.

12. The blowing agent adding device according to any one of claims 1 to 11, further comprising a flow rate adjusting mechanism for adjusting a flow rate of the blowing agent in the blowing agent flow path upstream of the on-off valve.

13. The blowing agent adding device according to claim 12, wherein the flow rate adjusting mechanism is a second on-off valve that controls, by opening and closing, the flow rate of the blowing agent flowing in the blowing agent flow path upstream of the on-off valve.

14. A foam spray machine comprising the foaming agent adding device according to any one of claims 1 to 13.

15. A foaming agent adding method for adding a foaming agent to a liquid supplied by a liquid pump and flowing through a liquid flow path, comprising: supplying a foaming agent contained in a foaming agent container to a foaming agent flow path; measuring the pressure of the blowing agent flowing through the blowing agent flow path with a blowing agent pressure gauge; measuring the pressure of the liquid flowing through the liquid flow path with a liquid flow path pressure gauge; a step of pressurizing the foaming agent flowing through the foaming agent flow path with a foaming agent pressure pump so that the pressure of the foaming agent measured by the foaming agent pressure gauge is lower than the pressure of the liquid measured by the liquid flow path pressure gauge; detecting the operation of the liquid pump with a pump operation detection unit; receiving the blowing agent flowing through the blowing agent flow path without receiving the liquid flowing through the liquid flow path, metering the blowing agent, and supplying a predetermined amount of the blowing agent to the liquid flow path with a blowing agent metering pump; and controlling the addition of the foaming agent to the liquid by opening and closing an on-off valve, a control unit that controls the opening and closing of the on-off valve in accordance with the driving status of the liquid pump detected by the pump drive detection unit, in the step of controlling the addition of the foaming agent by opening and closing an on-off valve.

16. 16. The foaming agent adding method according to claim 15, wherein in the step of controlling the addition of the foaming agent by opening and closing an on-off valve, when the pressure measured by the liquid flow path pressure gauge is lower than a predetermined value, the on-off valve is controlled not to open.

17. A method for producing a foam, comprising the step of adding a blowing agent to a liquid flowing through a liquid flow path by the method for adding a blowing agent according to claim 15 or 16.

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