JP2004089976A - Method for spraying liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for spraying a liquid capable of producing particulates of the liquid or a melt of the highest quality that can be made with a spraying or centrifugal atomization method, while the particulates can be applied to an object to be coated with a high coating efficiency by using a whirling flow which generates excess flow action of the fine particles and also can be granulated so that the granulated particulates are used as a granulated material for a pharmaceutical product, food and a chemical or the like. <P>SOLUTION: The method for spraying the liquid comprises a process of discharging at least one kind of liquid through a liquid discharge opening 7b, a process of generating a jet flow of the particles by squirting first compressed gas FG through a first compressed gas discharge opening 17b arranged around the liquid discharge opening 7b and thereby making the liquid LQ discharged through the liquid discharge opening 7b into the particles, and a step of squirting second compressed gas SG through multiple second compressed gas discharge openings 10b toward the jet flow of the liquid particles and bombarding the jet flow of the liquid particles with at least part of the second compressed gas SG so as to produce the particulates by swirling the jet flow of the liquid particles. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for spraying a liquid or a melt.
[0002]
[Prior art]
Conventionally, the following two methods are known as a method and an apparatus for spraying a liquid or a melt while applying a swirling flow with a compressed gas.
(1) In Japanese Patent Laid-Open No. 5-212334, a thin hot wire (one hot melt adhesive) (a high-temperature melt adhesive) is drawn from a nozzle member and stretched while swirling ( An improved swirl spray nozzle suitable for the manufacture of filaments is disclosed. Since this apparatus can apply a swirl continuous filament to an object to be coated at 100%, it is often used in a bonding process for manufacturing a paper diaper or a napkin.
[0003]
Further, as a method for solving the hook phenomenon at the start of filament discharge, which had a problem with this method, in Japanese Patent Laid-Open No. 9-136053, pressure is applied from air holes provided separately from a plurality of air nozzles for swirling flow. Produces a filament without hooks by spraying air and giving direction to the hot melt adhesive at the beginning of discharge almost in the direction of drooping, and swirling it by bringing pressurized air into contact with the hot melt adhesive from another air nozzle hole and stretching it. A method has been proposed.
[0004]
(2) On the other hand, the applicant of the present invention disclosed in Japanese Patent Laid-Open No. 4-4060 is a suitably swirled fiber filament or circle-shaped bead of a liquid or melt that has solved all the problems and problems of (1) above. Proposes a method of manufacturing dot patterns or fine particles to meet a wide range of applications. In this method, the jet of compressed gas for distributing filaments and fine particles can be forcibly rotated to distribute the liquid and melt into the desired form, so it depends on the type and viscosity of the liquid and melt. Hateful.
[0005]
[Problems to be solved by the invention]
However, the nozzles described in JP-A-5-212334 and JP-A-9-136053 in (1) are made of a material that easily forms a fiber filament such as a hot melt adhesive or a hot melt adhesive. Designed to suit. On the other hand, production of fine particles of a melt such as a coating agent, an adhesive, or paraffin wax that is liquid at room temperature and spray coating as fine particles have been attempted because of its good coating efficiency.
[0006]
However, the nozzle described in the above publication is manufactured for the purpose of making filaments and fibers, and is not designed for atomization, so a low-viscosity liquid of about 50 mPa · s or a molten lower viscosity of 10 mPa · s. Even with paraffin wax of s, the average spray particle size did not fall below 50 μm, and particles of 200 μm or more were often mixed. In addition, for example, the average particle size in the case of a solder resist having a viscosity of 300 mPa · s is several hundred μm, which is not suitable for coating a printed circuit board.
[0007]
On the other hand, the atomization by the method according to Japanese Patent Laid-Open No. 4-4060 of (2) is 50 mPa.s, which is said to be the minimum atomization region in the spray or centrifugal atomization method. It was possible to make the spray average particle size in the liquid of s 12 μm or less. However, this device is complicated and expensive, and requires a large space. In addition, when using highly combustible liquids such as organic solvents for high-precision applications, it is necessary to use a pressure-explosion-proof AC servo motor for the compressed gas nozzle rotation device, which is more expensive and wider. There were limited applications that needed space but had features.
[0008]
In recent years, functional materials such as functional coatings have been developed and the number of expensive materials is increasing. In addition, it is a spraying method that can produce finer particles than conventional spray nozzles for non-contact coating with a thin film without damaging the object to be coated or for wet-on-wet coating conditions. There is an increasing demand for a construction method that can obtain the same efficiency of use as a roll coater, screen coater or slot nozzle coater.
[0009]
Electrode ink for electrodes used for fuel cells proposed in US Pat. No. 5,415,888 (for application on both sides of the electrolyte membrane) In the process of making an electrode by applying a dispersion of carbon carrying a platinum and a polymer solution, an apparatus and a method capable of obtaining a high use efficiency of the coating agent as well as the coating film performance have been eagerly desired.
[0010]
The present invention has been made in view of the above-mentioned problems, and makes fine particles of liquid or melt that are equal to or better than the highest level in spraying and centrifugal atomization methods, and has a swirl flow that causes vortex action of the fine particles. Provided is a liquid spraying method that can be applied to an object to be coated with high coating efficiency, and that the fine particles can be granulated and used as a granulated product such as pharmaceuticals, foods, and chemicals. There is.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention employs the following liquid spraying method. That is, a step of discharging at least one liquid from a liquid discharge port, and a first compressed gas is discharged from a first compressed gas outlet provided around the liquid discharge port and discharged from the liquid discharge port A step of making the liquid into particles and creating a particle jet flow, and ejecting a second compressed gas from a plurality of second compressed gas outlets toward the liquid particle jet flow, and at least part of the second compressed gas into the liquid particle jet flow The above object is achieved by providing a spraying method including a step of making the liquid particle jet flow into a fine particle while rotating the liquid particle jet.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings.
FIG. 1 to FIG. 5 show an embodiment of a liquid spraying device used for carrying out a liquid spraying method according to the present invention. FIG. 1 is an overall system diagram (partly longitudinal sectional view) of the liquid spraying device. 2 is a vertical sectional view taken along the line II-II of the automatic discharge valve and nozzle assembly portion in FIG. 1, FIG. 3 is a bottom view taken along the line III of the automatic discharge valve and nozzle assembly portion in FIG. 1 is an enlarged view of a portion A in FIG. 1, and FIG. 5 is an enlarged view of a portion B in FIG.
[0013]
In these drawings, reference numeral 1 denotes an automatic liquid discharge valve. The automatic discharge valve 1 is connected to a liquid supply pipe 4 for sucking and sending the liquid stored in the tank 2 by a pump 3. Reference numeral 4 b denotes a liquid return pipe, and reference numeral 4 a denotes a connection tool between the pipe 4 or 4 b and the automatic discharge valve 1. The automatic discharge valve 1 is provided with a compressed air pipe 8 for opening and closing the needle 1a connected to the piston 1c with respect to the valve seat 1b by operating a piston 1c built in the automatic discharge valve 1 via a connector 8c. Connected. An air regulator 8a and a solenoid valve 8b are interposed in the compressed air pipe 8 from the upstream side to the downstream side. Reference numeral 1d denotes a spring (compression coil spring) for seating the needle 1a on the valve seat 1b and always biasing it.
[0014]
The automatic discharge valve 1 is equipped with a nozzle assembly 5. As shown in FIG. 2, a first compressed gas supply pipe 13 for supplying a first compressed gas (compressed air or the like) is connected to the nozzle assembly 5 via a connector. An air regulator 13a and a solenoid valve 13b are interposed in the gas pipe 13 from the upstream side to the downstream side. A solvent supply pipe 13 c is connected to the middle of the first compressed gas pipe 13. Further, as shown in FIG. 1, a second compressed gas supply pipe 11 for supplying a second compressed gas (compressed air or the like) is connected to the nozzle assembly 5 via a connector. The compressed gas pipe 11 is provided with an air regulator 11a and a solenoid valve 11b from the upstream side to the downstream side.
[0015]
As shown in detail in FIG. 4, the nozzle assembly 5 includes a liquid nozzle 7, an intermediate (solvent) disk 9, and an annular compressed gas nozzle 10 at a lower end portion of a main body 5a, and a fastener 5c as a nozzle assembly. By being screwed to the three-dimensional main body 5a, the three-dimensional main body 5a is firmly attached to the main body 5a in a state of being joined and crimped to each other. The liquid nozzle 7 has an upper surface pressed against the lower end surface of the main body 5a of the nozzle assembly, and a thin columnar protrusion extending in a downward tip direction extending through a low stepped disk portion at a central portion on the lower surface side. A liquid passage 7a is formed through the low and high stepped disk portion and the central portion in the longitudinal direction of the cylindrical protrusion.
[0016]
The intermediate (solvent) disk 9 has an upper surface outer periphery pressed against the lower surface outer periphery of the liquid nozzle 7 and a circular recess into which the low and high stepped disk portion of the liquid nozzle 7 is inserted at the center of the upper surface. In addition, an inverted conical protruding portion that protrudes in the lower tip direction through a cylindrical portion is formed in the central portion on the lower surface side, and the cylindrical protruding portion of the liquid nozzle 7 has an annular gap in the longitudinal center portion. An inner hole 17 is formed which is inserted with 17a. In addition, the annular compressed gas nozzle 10 has an inner hole formed in the center portion and fitted into the cylindrical portion of the intermediate disk 9, and the upper surface is pressed against the lower surface of the intermediate disk 9. Directed (refer to FIG. 4) and oriented slightly off the vertical center line of the liquid passage 7a of the liquid nozzle 7 (refer to FIG. 5) at a plurality of substantially equal intervals in the circumferential direction (eight in this embodiment). ) It has a second compressed gas passage 10a drilled through.
[0017]
Further, the liquid nozzle 7 is provided with a plurality of first compressed gas passages 16 penetrating in the longitudinal direction at equal intervals in the circumferential direction on the outer peripheral side of the liquid passage 7a, and further on the outer side, the second nozzle A plurality of compressed gas passages 7c are provided penetrating at equal intervals in the circumferential direction. Further, an upper annular groove 9a having a rectangular cross section is formed on the intermediate disk 9 at a position facing the second compressed gas passage 7c of the liquid nozzle 7 on the upper surface side, and the upper annular groove 9a is also formed on the lower surface side. The lower annular groove 9c is formed at substantially the same radial position, and the upper annular groove 9a and the lower annular groove 9c are communicated with each other through a communication hole 9b that is formed at equal intervals in the circumferential direction. The compressed gas nozzle 10 is formed with an annular groove 10c having a triangular cross-section serving as a starting point of the second compressed gas passage 10a at a radial position facing the lower annular groove 9c.
[0018]
On the other hand, in the main body 5a of the nozzle assembly 5, an annular groove 15a for the first compressed gas is formed on the lower end surface at a radial position substantially corresponding to the first compressed gas passage 16 of the liquid nozzle 7. A first compressed gas supply passage 15 connected to the annular groove 15a and extending in the vertical direction is provided. The first compressed gas supply passage 15 is connected to the first compressed gas pipe 13. Further, the main body 5a of the nozzle assembly 5 has a radial position substantially corresponding to the second compressed gas passage 7c of the liquid nozzle 7 on the lower end surface of the main body 5a at the outer position of the annular groove 15a for the first compressed gas. The second annular groove 5b for compressed gas is formed, and a second compressed gas supply passage 11c connected to the annular groove 5b and extending in the vertical direction is provided. The second compressed gas supply passage 11 c is connected to the second compressed gas pipe 11.
[0019]
The main body 5a of the nozzle assembly 5 is formed with a liquid supply passage 6 on the longitudinal center line so as to correspond to the position of the liquid passage 7a of the liquid nozzle 7. The valve 1 is communicated with a liquid passage 1e through which a needle 1a, which is a valve mechanism of the discharge valve 1, and a seat (valve seat) 1b are interposed. The liquid passage 1e of the automatic liquid discharge valve 1 is connected to the liquid supply pipe 4 through the valve mechanism.
[0020]
Thus, an annular space 16a having a required volume is formed between the lower surface of the stepped low and high disk portion of the liquid nozzle 7 and the bottom surface of the circular depression at the center of the upper surface of the intermediate disk 9, The annular space 16 a communicates with an annular gap 17 a formed between the outer peripheral surface of the columnar protrusion of the liquid nozzle 7 and the inner peripheral surface of the inner hole 17 of the intermediate disk 9. The annular gap 17a constitutes a first compressed gas passage (flow path), and the annular opening at the lower end of the annular gap 17a constitutes a first compressed gas outlet 17b. The annular space 16a functions as a first compressed gas supply path as described above, and is supplied from the solvent supply pipe 13c into the first compressed gas supply pipe 13 at the time of spraying work or when the work is interrupted. Thus, a necessary amount of the solvent is accumulated, and the liquid discharge port 7b is wetted by flowing out from the compressed gas outlet 17b alone or with the compressed gas through the annular gap 17a.
[0021]
In such a configuration, the liquid is sent from the liquid tank 2 to the pipe 4 by the pump 3, the liquid passage 1 e in which the valve mechanisms 1 a and 1 b of the automatic liquid discharge valve 1 are interposed, and the liquid supply passage of the nozzle assembly 5. 6 and the liquid passage 7 a of the liquid nozzle 7 and discharged from the liquid discharge port 7 b of the liquid nozzle 7. When the so-called valve mechanism is not closed, the liquid is returned to the tank 2 through the return pipe 4b. The first compressed gas is sent to the pipe 13 through the regulator 13a and the electromagnetic valve 13b by a first compressor (not shown) which is a compressed gas source, and further, the compressed gas supply passage 15 of the nozzle assembly 5, It passes through the annular groove 15a, the passage 16 of the liquid nozzle 7, the annular space 16a and the annular gap 17a and is ejected from a compressed gas outlet 17b which is an annular opening at the tip.
[0022]
As apparent from the above, an annular first compressed gas outlet 17b is formed around the liquid discharge port 7b. Further, as shown in an enlarged view in FIG. 4, in this embodiment, the liquid discharge port 7 b of the liquid nozzle 7 is formed inside the inner hole 17, that is, at a position retracted deeper than the lower end opening of the inner hole 17. That is, the liquid discharge port 7b is located on the inner side of the outlet from which the first compressed gas ejected from the compressed gas outlet 17b which is the annular opening of the first compressed gas is actually expanded and released into the atmosphere. Has been. Thus, the combination structure of the first compressed gas outlet 17b and the liquid discharge port 7b constitutes a so-called internal mix two-fluid ejection (spray) means. For this reason, the atomization of the liquid is extremely good.
[0023]
Further, the second compressed gas is sent to the pipe 11 via the regulator 11a and the electromagnetic valve 11b by a second compressor (not shown) which is a compressed gas source, and the second compressed gas supply of the nozzle assembly 5 is further supplied. The passage 11c, the annular groove 5b, the second compressed gas passage 7c of the liquid nozzle 7, the upper annular groove 9a of the intermediate disk 9, the communication hole 9b, the lower annular groove 9c, the annular groove 10c of the compressed gas nozzle 10, and the circumference A plurality of second compressed gas passages 10a arranged in the direction are flown and ejected from the second compressed air outlet 10b at the front end opening.
[0024]
In the present invention, as a liquid to be sprayed, for example, a liquid coating agent having a viscosity of 30 to 70 mPa · s such as an acrylic epoxy waterbone coating agent for inner surface coating of a beverage can, for example, a particle size of 0.1 to 80 μm Dispersion dispersed in a liquid for coating the inner surface of an alkaline battery having a carbon particle viscosity of 20 to 80 mPa · s, a solder resist having a viscosity of 50 to 300 mPa · s used for coating a printed circuit board, or fuel Dispersion (electrode ink) made of carbon and polymer solution carrying platinum for application on both sides of the electrolyte membrane used for battery electrodes is applied for atomization, and as a melt, the viscosity is 5 to 800 mPa · s paraffin wax, microphone Crystalline waxes, melt such as polyethylene wax and Otsu (Otsu) blown asphalt is applied as a atomization.
[0025]
Next, a liquid spraying method using the liquid spraying device configured as described above will be described.
The liquid stored in the tank 2 is sucked up and pressurized by the pump 3 to the automatic discharge valve 1 and sent through the pipe 4. Then, the solenoid valve 8b is excited, compressed air is sent from the compressed air source to the compressed air pipe 8, and is sent to the lower surface of the piston 1c of the automatic discharge valve 1 via the air regulator 8a. The piston 1c is lifted against the urging force of the spring 1d, the needle 1a is separated from the valve seat 1b, and the automatic discharge valve 1 is opened (see FIGS. 1 and 2). Then, the liquid passes through the liquid passage 1e of the automatic discharge valve 1 and the liquid supply flow path 6 processed almost near the center of the nozzle assembly 5, and further passes through the liquid passage 7a of the liquid nozzle 7 from the liquid discharge port 7b. It is discharged as a liquid discharge flow LQ.
[0026]
When the solenoid valve 13b of the first compressed gas pipe 13 is excited in the nozzle assembly 5, the first compressed gas passes through a regulator 13a from a first compressor (not shown) as a compressed gas source. 2 (see FIG. 2), the compressed gas supply passage 15 of the nozzle assembly 5, the annular groove 15a, the passage 16 of the liquid nozzle 7, the annular space 16a and the annular gap 17a are passed through the annular opening at the tip. 4 is ejected from the compressed gas outlet 17b in the direction indicated by a chain line arrow (FG) in FIG. 4, and the liquid discharge flow LQ discharged from the liquid discharge port 7b of the liquid nozzle 7 is particleized as described above to generate a particle jet flow. Is made. At this time, as described above, since the combination of the first compressed gas outlet 17b and the liquid discharge port 7b has an internal mix two-fluid jet (spray) structure, the liquid discharge flow LQ is formed inside the inner hole 17. Since the compressed gas having a high pressure before coming out of the lower end opening of the inner hole 17 from its surroundings and being released into the atmosphere and expanded is brought into contact with each other to perform the mixing action, the liquid is atomized very well. In the present invention, the method of creating the liquid particle jet flow by the first compressed gas is not limited to the application of the internal mix two-fluid jet structure, and the application of the external mix two-fluid jet structure is also possible. It is.
[0027]
Then, the solenoid valve 11b of the second compressed gas pipe 11 is excited in the nozzle assembly 5, and the regulator 11a is supplied from a second compressor (not shown) whose second compressed gas is a compressed gas source. (See FIG. 1), the gas passage 11c of the nozzle assembly 5, the annular groove 5b, the passage 7c of the liquid nozzle 7, the upper annular groove 9a of the intermediate disk 9, the communication hole 9b, and the lower annular groove 9c. Further, the compressed gas nozzle 10 is further flown into the annular groove 10c of the compressed gas nozzle 10 and a plurality of second compressed gas passages 10a arranged at substantially equal intervals in the circumferential direction, and the second compression of each tip opening is performed. It is ejected from the air outlet 10b in the direction indicated by the chain line arrow (SG) in FIGS.
[0028]
The respective second compressed gases SG ejected from the plurality of second compressed air outlets 10b are slightly removed (offset) from the vertical center lines of the liquid passage 7a and the liquid discharge port 7b of the liquid nozzle 7. Since the liquid is ejected in the direction and expands, at least a part of the liquid collides with or comes into contact with the liquid particle jet flow that has been granulated with the first compressed gas as described above to form a swirl flow FW of liquid fine particles (see FIG. 2). . By the collision or contact of the second compressed gas SG, the liquid that has not yet been atomized is atomized, and the atomization of the liquid particle jet flow is promoted.
[0029]
Then, as shown in FIG. 2, the swirl flow FW of the liquid fine particles reaches the object SB that is sequentially sent to a position just below the nozzle assembly 5 by transfer means such as a conveyor to form the swirl flow FW. The fine particles FP are applied to the surface of the object SB to form a thin film CF. When the fine particles FP are applied to the coating object SB, the liquid fine particle group forms the swirl flow FW, so that each fine particle FP contacts the coating object SB in a state where the fine particles FP are caught in the swirl flow FW. Therefore, the amount of fine particles that are rebounded (repelled) by the collision with the coating object SB is extremely small, and the generation of turbulent flow due to the collision of the gas forming the swirl flow FW with the coating object SB is as much as possible. By being suppressed, the coating (coating) efficiency of the fine particles is greatly improved.
[0030]
In the liquid spray apparatus of this embodiment, as shown in FIG. 2, a solvent supply port 13d is connected to a first compressed gas supply pipe 13 and a solvent supply pipe 13c is attached, and the solvent is supplied to the solvent supply port 13d. The first compressed gas supply path, that is, the compressed gas supply passage 15, the annular groove 15a of the nozzle assembly 5, the passage 16 of the liquid nozzle 7, the annular space 16a is supplied to the pipe 13c and mixed into the first compressed gas. The compressed gas outlet 17b, which is the annular gap 17a and the annular opening at the tip, can be fed together with the first compressed gas. As a result, the liquid discharge port 7b of the liquid nozzle 7 can always be wetted with the solvent during the spraying operation, and even when the liquid containing the volatile component is sprayed, the liquid discharge port 7b is moved to the vicinity of the liquid discharge port 7b. Thus, it is possible to maintain a constant coating thickness and coating weight by preventing the phenomenon of skinning due to liquid build-up of the coating agent, preventing the narrowing and clogging of the flow path and stabilizing the liquid discharge amount.
[0031]
In addition, when the spraying of the first compressed gas is stopped, for example, when the spraying operation is stopped, the solvent is sent alone into the system through the solvent supply pipe 13c, and a predetermined amount is accumulated in the annular space 16a so that the annular gap The liquid discharge port 7b of the liquid nozzle 7 can be wetted with a solvent by flowing out through 17a and the compressed gas outlet 17b. Furthermore, in the present invention, the solvent supply pipe 13 c is inserted into the first compressed gas supply path (13, 15, 15 a, 16, 16 a, 17 a), and its discharge port is in the vicinity of the liquid discharge port 7 b of the liquid nozzle 7. It is also possible to configure it by positioning it. When the solvent supply pipe is configured in this way, the liquid discharge port 7b can be moistened instantaneously when the spraying operation is stopped. By doing as described above, it is possible to prevent the volatile matter in the liquid when resting for a predetermined time or the skinning phenomenon near the liquid discharge port 7b due to the drying of the liquid itself.
[0032]
In this embodiment, an internal mix two-fluid spray structure is adopted and atomization is performed well. On the other hand, for example, a coating agent or an adhesive containing a volatile component evaporates instantly. In this embodiment, the first compressed gas jet 17b and the liquid discharge port 7b and the liquid discharge port 7b are likely to be covered and the continuous operation becomes impossible. Since the vicinity of the discharge port 7b is moistened with the solvent, spraying by atomization of the liquid can be performed very smoothly and continuously without such a situation.
[0033]
In the present invention, the above-described liquid spraying operation is further performed by continuously supplying and ejecting the first and second compressed gases and discharging the liquid by a high-speed intermittent operation. As shown in FIG. 6, the opening time and closing time of the needle 1a are set to a predetermined extremely short time such that the opening time (liquid discharge time) of the needle 1a is 15 ms (milliseconds) and the closing time (liquid supply stop time) is 30 ms. The time is set so that the opening and closing operation of the needle 1a is repeated cyclically, and the opening amounts of the needle 1a and the seat 1b are increased by a predetermined amount, and the discharge amount is set to be a predetermined amount higher than the flow rate during continuous discharge. By performing so-called pulsed (intermittent) spraying, liquids containing solid particles such as carbon particles, such as so-called dispersion type and powder slurry liquids, Prevent clogging of the the gap due to the narrow gap in said solid particles between the automatic ejection of the valve 1 needle 1a and the sheet 1b are aggregated effectively, stable amount can be discharged continuously.
[0034]
This is because even if solid particles aggregated between the needle 1a and the sheet 1b are clogged in the gap, the clogged foreign matter is pushed out by a high-speed closing operation with an impact of the needle 1a on the sheet 1b. This is because it is considered possible. In such an intermittent opening / closing operation of the needle 1a, a controller having a timer (not shown) is connected to the solenoid valve 8b of the compressed air pipe 8 for opening / closing the needle 1a, and the opening / closing timing of the needle 1a is controlled by the timer. This can be done by setting. In the present invention, when the liquid is ejected by high-speed intermittent operation at a cycle of 60 cycles or more per minute, clogging due to aggregation of solid particles in the liquid in the gap between the needle 1a and the sheet 1b is effective. Can be prevented.
[0035]
Further, at least the first compressed gas can be intermittently supplied and ejected in synchronism with the discharge by the intermittent operation of the liquid. A controller incorporating a timer (not shown) is also connected to the solenoid valve 13b attached to the first compressed gas supply pipe 13, and the timer supplies and stops the first compressed gas, for example, as shown in FIG. Each time is set to 30 ms, while the needle 1a is opened, for example, by 20 ms and the liquid is discharged by 20 ms within the supply jetting time (30 ms) of the first compressed gas. In this case, 5 ms (t ₁ ) After that, supply of liquid was started, and 5 ms (t ₂ ) The liquid discharge is stopped before. Accordingly, the liquid has a discharge time of 20 ms and a discharge stop time of 40 ms, and this cycle is repeated. Similarly to the first compressed gas, the second compressed gas can be intermittently supplied and ejected.
[0036]
In this way, at least the first compressed gas is ejected for a predetermined short time before and after the liquid is ejected, so that the generation of large droplets at the start and end of the ejection is effectively eliminated. At the same time, it is possible to perform spraying work by atomizing a suitable liquid from the start to the end of discharge. And by at least intermittently supplying and ejecting at least the first compressed gas that effectively contributes to the atomization of the liquid in this way, the rebound by the continuous supply of the first compressed gas (due to the collision with the workpiece SB) As a result of preventing reflection, the amount of liquid fine particles and solid fine particles contained in the liquid is drastically reduced, and the coating efficiency is effectively improved. In the present invention, regardless of whether the compressed gas is continuously or intermittently supplied, if the first compressed gas is ejected at least 1 ms to 200 ms before and after the liquid is ejected, suitable atomization from the beginning to the end of the spray is achieved. The coating operation can be effectively performed.
[0037]
The liquid spray method of the present invention is not limited to the case where the liquid fine particles obtained by spraying are applied to the article SB as described above, and can be sprayed and granulated in the air. For example, a substance having a softening point (for example, 65 ° C.) higher than the temperature of air in a spray atmosphere as a liquid (for example, paraffin wax which is a biodegradable material) has a temperature higher than the softening point (for example, 100 ° C.). The first and second pressurized gases are heated to a temperature above the softening point of the substance (for example, 120 ° C.) via a hot air generator, and the heated melt is liquid. By spraying into the air from the discharge port 7b, it can be cooled and solidified in the air and granulated into a fine particle shape, which can be freely dropped and recovered. In addition, the biodegradable container provided with the barrier film | membrane can also be manufactured by performing the spray of the heating melt of the said paraffin wax directly on to-be-coated objects, such as a pulp mold container.
[0038]
Further, in the present invention, the liquid passage 7a and the liquid discharge port 7b of the liquid nozzle 7 have a double structure, and different liquids are discharged from the inner passage and the outer passage to atomize, so that 2 outside the nozzle assembly. The liquid can be mixed and sprayed, for example, applied to an object to be coated, and can be the same as that obtained by mixing and spraying two liquids in advance.
[0039]
In addition, as the first and second compressed gases described above, compressed air is usually used, but in addition to this, it can be properly used depending on the properties and properties of the liquid to be discharged. For example, when the liquid is flammable Nitrogen gas or carbon dioxide gas can be used.
Further, although the intermediate disk 9 and the compressed gas nozzle 10 are formed separately, both may be formed integrally. Further, the liquid discharge nozzle 7 may be integrally formed.
[0040]
Next, experimental examples such as coating by the liquid spraying method of the present invention will be described.
[0041]
[Experiment 1]
As a coating agent as a liquid, an acrylic epoxy waterborne coating [NV: 20%, viscosity: 20 seconds / FC # 4 (Ford cup # 4, equivalent to about 40 mPa · s with a B-type viscometer)] Experiments were performed under the following conditions using 100 mm × 100 mm size aluminum foil (aluminum foil) as the object to be coated.
(1) Hydraulic pressure (pump 3 discharge pressure); 0.06 MPa
(2) First compressed gas; air from the first compressor: 0.05 MPa
(3) Second compressed gas; air from the second compressor: 0.15 MPa
(4) Liquid discharge flow rate: 10 ml / min
(5) Distance between the nozzle (the lower end of the opening of the inner hole 17 of the liquid nozzle 7) and the object to be coated; 100 mm (6) Conveyor speed for conveying the object to be coated; 0.3 m / min
(7) Nozzle discharge port (liquid discharge port 7b) diameter: 0.7 mm
(8) Application pattern width: almost circular 25 mm
(9) Traverse speed of automatic discharge valve 1 and nozzle assembly 5 during application;
24 m / min, traverse stroke; 270 mm, traverse cycle;
30c / min
(10) Sampling frequency: 3 times
[0042]
The spray is applied from the liquid discharge port 7b of the nozzle assembly 5 while traversing the combination of the automatic discharge valve 1 and the nozzle assembly 5 to the aluminum foil as the object SB to be transferred by the conveyor under the above conditions. It was. As a result, the leveling state of the coated surface with good atomization during spraying was also good. After setting at room temperature for about 3 minutes and drying at 200 ° C. for 2 minutes, the weight was measured, and the value obtained by subtracting the weight of only the aluminum foil measured in advance was 161.3 mg. The coating efficiency obtained from a theoretical weight of 200 mg (the specific gravity of the solid content is almost 1 so that the theoretical application time of the coating is 6 seconds × solid content) was 80.7%. Moreover, the mirror surface equivalent to the aluminum foil surface was observed on the coating surface after drying.
[0043]
[Comparative Example 1]
A two-fluid spray gun manufactured by Nordson Corporation (name: AD-29 gun, a gun having a compressed gas outlet near the liquid discharge port) and used for atomization ejected from the compressed gas outlet The experiment was performed under the same conditions as in Experimental Example 1 except that only the first air from the first compressor was used as the air. The coating pattern was an ellipse pattern with a minor axis of 15 mm and a major axis of 35 mm. A large particle size was visually observed, and bubbles were generated on the wet surface. It was 98.6 mg when it dried on the same dry conditions as Experimental Example 1 and the coating-film weight was measured. The coating efficiency is 49.3%. About 20 microbubbles were observed in the dried coating film. Also, the fluorescent lamp projected on the coating surface was jagged like the saw tooth.
[0044]
[Comparative Example 2]
Sampling was performed under the same conditions as in Experimental Example 1 except that only the second air from the second compressor was used using the nozzle described in JP-A-5-212334. Visually observed spray particles were generally large and looked about twice as large as Experimental Example 1. Further, it was observed that particles larger than Comparative Example 1 were scattered. The wet surface was worse than that of Comparative Example 1, and innumerable microbubbles were generated in the dried coating film, and even craters produced with foreign matter, oil, etc. as the core were scattered. However, the dry weight was 163.4 mg and the coating efficiency was 81.7%, which was almost the same as in Experimental Example 1.
[0045]
[Experimental example 2]
Next, as a coating agent as a liquid, a carbon dispersion having a viscosity of 40 mPa · s similar to the carbon ink coated for the inner surface of the alkaline dry battery or the electrode of the fuel cell is used, and the above-mentioned three kinds of spray nozzles are used. A spray nozzle, that is, a combination of an automatic discharge valve 1 and a nozzle assembly 5 used for carrying out the method of the present invention, an AD-29 gun which is a two-fluid spray gun, and a nozzle disclosed in Japanese Patent Laid-Open No. 5-212334 are used. In each case, the test was performed with the same wet flow rate of the solvent type carbon dispersion.
[0046]
In either case, the spray pattern started to be disturbed around the second sampling, and the weight was halved. The operation was stopped because the carbon particles were agglomerated and it was found that the flow rate was unstable due to clogging at the narrow clearance between the needle and the sheet when the automatic discharge valve was opened.
[0047]
[Experiment 3]
Japanese Patent Application Laid-Open No. 61-161175 proposed by the present inventors in the combination of the automatic discharge valve 1 and the nozzle assembly 5 used in the practice of the present invention using the coating agent of Experimental Example 2 described above. The pulsed (intermittent) spraying method disclosed in “Two-fluid spraying method” was applied. The first and second compressed air were continuously supplied and jetted, the carbon dispersion spray opening time (needle opening time) was 15 milliseconds, and the closing time (needle closing time) was 30 milliseconds. In order to make the spray flow rate from the nozzle the same, the continuous flow rate was increased to 30 ml / min. The spray flow rate with pulses (intermittent) was about 10 ml / min. Immediately after starting with a graduated cylinder, the flow rate was measured after 3 minutes, 5 minutes and 10 minutes, but the flow rate was stable.
[0048]
Furthermore, the flow rate was stable even when the continuous flow rate was 10 ml / min, the same as in Experimental Example 2, the pulse setting was the same as in Experimental Example 3, and the pulse spray flow rate was about 3.3 ml / min. This is presumably because, even if the carbon particles aggregated between the needle and the sheet are clogged, the pushing action is performed by the closing operation of the ultra-high speed needle 1a accompanied by an impact. If the flow rate per minute is reduced, dry fine particles can be produced. Utilizing this phenomenon is useful because it has the effect of speeding up drying without swelling the electrolyte of the fuel cell.
[0049]
[Experimental Example 4]
When the spraying operation was interrupted for 5 minutes and restarted under the conditions of Experimental Example 1, the flow rate of the coating agent dropped to about 6 ml / min, which was about half. This was a phenomenon that occurred as a result of the coating agent built up around the tip of the coating agent discharge nozzle, that is, around the liquid discharge port 7b, being skinned and the flow path was narrowed. Therefore, ion exchange water at a flow rate of 1 ml / min is supplied as a solvent to the solvent supply pipe 13 c connected to the first compressed gas supply pipe 13 shown in FIG. 2, and the first compressed gas supply path inside the nozzle assembly 5 is supplied. When the coating agent was sprayed while being guided to the compressed gas outlet 17b through the annular space 16a and the compressed gas passage 17a and atomizing the ion exchange water with the air of the first compressor, the coating surface before and after drying There was no effect on the coating and no change in coating weight. In addition, build-up of the coating agent on the nozzle tip (near the liquid discharge port 7b), that is, so-called skinning did not occur.
[0050]
Further, it was confirmed that there was no change in the flow rate of the coating agent 5 minutes after the spray work, and that there was no problem in the normal work, but it decreased to less than half after 45 minutes of the lunch break. Therefore, when the spraying operation was interrupted, the ion exchange water was continuously allowed to flow out, and the tip of the coating agent discharge nozzle was always moistened. Further, the internal mix spray means in which the particle formation by the first air is the best, that is, the liquid discharge port 7b is a discharge port formed at a position where the first compressed gas actually goes out to the atmospheric atmosphere, that is, an intermediate disk. Even in the case of a structure located inside the lower end of the opening of the inner hole 17 of 9, there was no problem of flow rate change due to skinning.
[0051]
In this experiment, the outlet of the coating agent discharge nozzle (liquid discharge port 7b) is a first compressor air discharge port (inner hole in the cylindrical protrusion at the tip of the liquid nozzle 7 as shown in FIG. 4). The lower end of the 17 opening) was recessed by 0.5 mm. In a normal two-fluid spray, a structure in which the liquid discharge port protrudes by about 0.1 mm to 0.8 mm is common. Normally, the internal mix 2 fluid spray is an ideal spray method with good atomization, but coating agents and adhesives containing volatile components are not used because the volatile components evaporate instantly and the air outlets are covered. . According to the present invention, this problem can also be solved.
[0052]
[Experimental Example 5]
Paraffin wax having a softening point of 65 ° C., which is a biodegradable material, was heated and melted to 100 ° C., and the discharge nozzle diameter (the diameter of the liquid discharge port 7b) was 0.2 mm, and the liquid pressure was 0.12 MPa. The first air has an internal mix structure of 0.1 MPa, the second air is set to 0.3 MPa, and hot air of 120 ° C. is supplied from an air supply source via a hot air generator, and sprayed into the air. Bran granulation was performed. The spray discharge rate was 7 g / min. The fine particles that solidified in the air and dropped freely were measured and found to be spherical with an average particle diameter of 12 μm. Of course, a biodegradable container provided with a barrier film can also be produced by spraying directly on an object to be coated such as a pulp mold container.
[0053]
[Experimental Example 6]
The liquid discharge port has a double structure, and is supplied by a volumetric pump so that isocyanate as a curing agent is 1 part by weight from the inner discharge port and 10 parts by weight of polyol as the main agent from the outer discharge port. Spray coating was performed on the coating SB. The viscosity of the polyol was 18 seconds / FC # 4. The coating film performance by the rubbing test after the solvent was flushed and dried was the same as that obtained by spraying two liquids in advance. In the present invention, it was also proved that an external mixing spray of a plurality of liquids was possible.
[0054]
【The invention's effect】
As is clear from the above description, according to the present invention, fine particles of liquid or melt that are equal to or better than the highest level in spraying and centrifugal atomization methods can be produced, which causes the vortex action of the fine particles. It has the outstanding effect that it can apply | coat to a to-be-coated object with high coating efficiency with the swirling flow to make. Moreover, the outstanding effect that the microparticles | fine-particles can be granulated and can be used as granules, such as a pharmaceutical, a foodstuff, and a chemical | drug | medicine is also show | played.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a liquid spraying device used for carrying out a liquid spraying method according to the present invention, and is an overall system diagram (partly longitudinal sectional view) of the liquid spraying device.
2 is a longitudinal sectional view taken along line II-II of the automatic discharge valve and nozzle assembly portion in FIG.
3 is a bottom view of the automatic discharge valve and nozzle assembly portion in FIG.
4 is an enlarged view of a portion A in FIG.
FIG. 5 is an enlarged view of part B in FIG. 3;
FIG. 6 is a diagram showing an example of a cycle pattern of a liquid pulse (intermittent) spray.
FIG. 7 is a diagram showing another example of a cycle pattern of a liquid pulse (intermittent) spray.
[Explanation of symbols]
1 Liquid automatic discharge valve
1a Needle (Valve)
1b Seat (valve seat)
2 Liquid tank
3 Liquid pump
4 Liquid supply piping
5 Nozzle assembly
6 Liquid supply channel
7 Liquid nozzle
7a Liquid passage
7b Liquid outlet
8 Compressed air piping
8a Air regulator
8b Solenoid valve (solenoid valve)
9 Intermediate (solvent) disc
10 Compressed gas nozzle
11 Second compressed gas supply pipe
11a regulator
11b Solenoid valve (solenoid valve)
13 1st compressed gas supply piping
13a regulator
13b Solenoid valve (solenoid valve)
13c Solvent supply tube
15, 15a, 16, 16a, 17a, 17b First compressed gas supply path
17b First compressed gas outlet
11c, 5b, 7c, 9a, 9b, 9c, 10c10a, 10b Second compressed gas supply path
10b Second compressed gas outlet
LQ liquid discharge flow
FG 1st compressed gas
SG Second compressed gas
FP fine particles
FW Fine particle swirl
CF coating
SB substrate

Claims (7)

A method of spraying liquid, the step of discharging at least one liquid from a liquid discharge port, and a first compressed gas ejected from a first compressed gas outlet provided around the liquid discharge port, A step of making particles discharged from a liquid discharge port into particles and creating a particle jet flow; and jetting a second compressed gas from a plurality of second compressed gas outlets toward the liquid particle jet flow, and the liquid particle jet flow A method of spraying liquid, comprising the step of causing at least a portion of the liquid particle to collide with the liquid particle and turning the liquid particle jet flow into a fine particle. The liquid spraying method according to claim 1, wherein the liquid is a melt. As a step of forming a particle jet flow by particleizing the liquid, a position where the discharge port of the liquid is expanded by being blown into the actual atmospheric atmosphere after the first compressed gas is jetted from the first compressed gas outlet 3. The liquid spraying method according to claim 1 or 2, further comprising using an internal mix two-fluid ejecting means located on the inner side. 4. The liquid spraying method according to claim 1, wherein the liquid contains a volatile component and at least the first compressed gas contains a solvent. A solvent supply port or discharge port is provided at least in the flow path of the first compressed gas, and when the compressed gas ejection is stopped, the liquid is discharged as a solvent liquid film via the first compressed gas outlet. 5. The liquid spraying method according to claim 1, wherein the outlet is wetted with the solvent. 6. The liquid spraying method according to claim 1, wherein at least the liquid is discharged by a high-speed intermittent operation at 60 cycles / minute or more. 7. The liquid spraying method according to claim 1, wherein at least the first compressed gas is ejected longer by 1 to 200 milliseconds before and after the liquid is ejected.

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