JPH0334988B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to the application of surface modifiers, colorants, and adhesives to synthetic resin molded products, paper, cloth, wood, ceramics, etc., and the surface treatment of metals, etc. Furthermore, the present invention relates to a method of applying a coating liquid used for applying food additives, etc.

[Conventional technology]

To apply and form a film made of a surface modifier such as an antistatic agent on the surface of a synthetic resin molded product, the object to be treated is immersed in a solution or aqueous dispersion of the surface modifier, or with a brush, etc. A coating of surface modifier is formed on the surface of synthetic resin molded products by coating or kneading a surface modifier into the raw material during synthetic resin molding and bleeding it onto the surface. In this method, the coating of the surface modifier becomes too thick and easily peels off due to friction or the like, uneven coating occurs, the coating is easily moved, and it is difficult to obtain a stable and uniform coating.

Therefore, the surface modifying agent is made into a mist or aerosol consisting of fine particles, and this mist or aerosol is sprayed onto the object to be treated, thereby forming a uniform and stable ultra-thin film on the surface of the object to be treated, resulting in a long-term surface modification effect. A method has been developed by the Applicant to provide retention over an extended period of time.

[Problems to be solved by this invention]

In this mist or aerosol application, the particle size is preferably made as small as possible, about 100 μm or less, but such fine particles repel each other and are stably suspended in the air to form an aerosol. Therefore, this aerosol has very weak adhesion to the object to be treated, and has so-called poor wettability.
Particularly in the case of complex synthetic resin molded products, or when the surface of paper, cloth, or fiber has complex irregularities, the permeability of particles to every corner of the surface is affected by the influence of these surface shapes.

Apart from this, it is difficult to form fine particles when the viscosity of the coating liquid is high.

[Means for solving problems]

The present invention has been made in view of these points, and particularly relates to a coating method that can be used not only for surface modifiers such as antistatic agents, but also for all coating liquids.

That is, in this invention, the object to be treated is placed in a sealed processing chamber, the pressure inside the processing chamber is first reduced, and in this state, a coating liquid such as a surface modifier is converted into an aerosol consisting of many fine particles and transferred into this processing chamber. , the aerosol in the processing chamber is diffused into a supersaturated state, and a film made of the components of the aerosol is formed on the surface of the object to be processed.

[Effect]

In this way, the object to be processed is placed in the processing chamber, and the pressure in the processing chamber is reduced at least before aerosol spraying, so when the aerosol is transferred into the reduced pressure processing chamber, the aerosol is sucked into the processing chamber, speeding up its diffusion. , it immediately becomes supersaturated. Therefore, the aerosol quickly penetrates into the finely uneven surfaces and elongated tubes of the workpiece, and when the aerosol comes into contact with the workpiece in such a supersaturated state, it immediately adsorbs or adheres to the surface of the workpiece. Then, the adsorbed or adhered moisture in the aerosol is vaporized, and a film made of the components of the aerosol is formed on the surface of the object to be treated.

Furthermore, if the processing chamber in which the aerosol is sprayed is maintained in a reduced pressure state as described above, even if the viscosity of the coating liquid is high, the aerosol generator can generate an aerosol consisting of fine particles. Therefore, if the viscosity of the coating liquid is low, the pressure in the processing chamber can be reduced before spraying the aerosol to speed up the diffusion of the aerosol within the processing chamber, and the internal pressure in the processing chamber will gradually rise as the aerosol is injected. However, if the coating liquid has a high viscosity, it is necessary to keep the pressure in the processing chamber below atmospheric pressure before the aerosol is sprayed and throughout the entire time the aerosol is being injected.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

First, to explain the equipment used in this method, 1 is a roughly box-shaped equipment main body, 2 is this equipment main body 1
A processing chamber is provided at the front of the processing chamber 2 and has a space for storing objects to be processed. Reference numeral 3 is an opening and closing door provided at the front of the processing chamber 2 that can be freely opened and closed. By closing the opening and closing door 3, the processing chamber 2 is hermetically sealed, and the processing chamber 2 has a pressure-resistant structure. 4 is an aerosol spray chamber provided at the rear of the processing chamber 2; 5 is an aerosol sprayer provided at the bottom of the aerosol spray chamber 4;
A surface modifier solution is introduced from a tank 6 containing the solution, and a compressor (not shown) sends compressed air through an air pipe 7 to atomize a large number of fine particles (preferably 100 microns or less). The upper surface of this aerosol spray chamber 4 has an inclined reflection plate 4a.
The distance between this reflecting plate 4a and the nozzle 5a of the aerosol sprayer 5 is set at 300 to 500 mm. 8 is an aerosol discharge port provided on the top surface of the aerosol spraying chamber 4 that continues to the top end of this reflector plate 4a;
This aerosol discharge port 8 faces the upper part of the processing chamber 2 . 9 is a gutter provided at the upper part of the processing chamber 2 on the opposite side from the aerosol discharge port 8; 10 is the mesh-like upper bottom plate of the processing chamber 2; and 11 is the mesh-like upper bottom plate 10.
The tank 6 whose top surface is open is located below the mesh bottom plate 11, which is provided below the mesh bottom plate 11 and has a finer mesh. 12 is the processing chamber 2
The lower part of the exhaust duct 12 communicates with the processing chamber 2 through the mesh upper bottom plate 10. 13 is a liquefied material that blocks the middle of each of these exhaust ducts 12; 14 is an exhaust slit provided at the top of each of these exhaust ducts 12;
Each of these slits 14 is exposed on both outer surfaces of the main body 1, and the width of the gap between the slits is adjustable. 15 is the liquefied material 13 and the exhaust slit 1
4, a pressure reducing device provided in the exhaust duct 12 between the
16 is a pipe that hangs down from the lower part of the aerosol spray chamber 4 into the tank 6.

Next, an embodiment of the method will be described based on the apparatus of this embodiment. First, the opening/closing door 3 is opened, the object to be processed 17 is put into the processing chamber 2, and the opening/closing door 3 is closed again. At this time, as shown in the figure, a large number of objects 17 to be processed can be placed on a shelf or the like placed inside the processing chamber 2. As a result, the processing chamber 2 is sealed. Then, the pressure reducing device 15 is operated to reduce the pressure in the processing chamber 2 and the aerosol spraying chamber 4 to below atmospheric pressure as shown in FIG.
When a compressor (not shown) is operated in this state, the solution in the tank 6 is guided to the aerosol sprayer 5.
The compressed air passed through the air pipe 7 from the compressor converts the particles into a large number of fine particles having a particle size of about 100 μm or less and sprays them from the nozzle 5a into the aerosol spray chamber 4. Then, since the pressure in the aerosol spray chamber 4 is reduced, the aerosol instantly diffuses. The ejected and diffused particles hit the reflection plate 4a, and only the small particles are carried by the air and discharged from the discharge port 8 into the processing chamber 2 as an aerosol.The large particles hit the reflection plate 4a and are liquefied there, and are transferred to the aerosol spraying chamber. 4 Falling to the bottom. The particles sprayed by the aerosol sprayer 5 in this manner are selected for their particle sizes, and only stable aerosols having small particle sizes (average particle size 10 μm) are injected into the processing chamber 2.
Further, since the pressure inside the processing chamber 2 is reduced from atmospheric pressure, the aerosol that enters the processing chamber 2 is sucked and rapidly diffuses, and the aerosol gradually fills up, becomes highly dense, and stabilizes in a supersaturated state. Then, the atmospheric pressure inside the processing chamber 2 gradually becomes higher than the atmospheric pressure as shown in A in FIG. It adsorbs or adheres immediately upon contact with the treated material. Then, the solvent such as water in the aerosol adsorbed or adhered to the surface of the object to be treated 17 evaporates, and the components of the surface modifier dry up to form a film. The thickness of this coating is proportional to the particle size and density of the aerosol. Also, depending on the amount of aerosol attached, aggregates of micro particles may be formed. In addition, the aerosol that did not adhere to the object to be processed is removed from the mesh upper bottom plate 1 of the processing chamber 2.
0, reaches the exhaust duct 12, and passes through the liquefied material 13. Here, the air or other gas in the aerosol is exhausted from the exhaust slit 14 to the outside of the device body 1 through the liquefaction material 13, and the components of the aerosol are liquefied by the liquefaction material 13, and the components of the aerosol are liquefied to the outside of the device body 1 as appropriate. or returned to tank 6. On the other hand, the solution accumulated in the lower part of the aerosol spray chamber 4 is transferred to the pipe 1.
6 and return to tank 6. In this manner, the processing chamber 2 is filled with aerosol, and after a certain period of time, the operation of the aerosol sprayer 5 is stopped, and the operation of the pressure reducing device 15 is also stopped, and the opening/closing door 3 is opened to take out the object 17 to be processed. As a result, a uniform coating made of the surface modifier is formed on the surface of the object 17 to be treated.

Further, when the viscosity of the coating liquid such as a surface modifier is high, the results are somewhat different from the above embodiments. In this case, the object to be processed 17 is placed in the processing chamber 2, and the pressure in the processing chamber 2 and the aerosol spraying chamber 4 is lowered to below atmospheric pressure before aerosol spraying as in the above embodiment, and in this state, the aerosol sprayer Aerosol is sprayed from Nols 5a of No. 5. Then, regardless of the high viscosity of the coating liquid, it is sprayed as fine particles, and the pressure in the processing chamber 2 and the aerosol spraying chamber 4 is kept below atmospheric pressure at all times during aerosol spraying, as shown in B and C in Figure 3. .

Note that FIG. 3 shows changes in the pressure in the processing chamber 2 and the aerosol spraying chamber 4, where the vertical axis represents the pressure p, the horizontal axis represents the elapsed processing time t, and FS represents the starting point of the pressure reducing device 15;
A and S indicate the starting point of the aerosol sprayer 5.

Further, in each of the above embodiments, when the object to be treated is put into the processing chamber 2 and subjected to coating treatment, the object to be processed 17 is supported in the processing chamber 2 by a suitable rotating support 18 as shown in FIG. When the aerosol is rotated at low speed, moved up and down, or vibrated, the aerosol further penetrates into the surface of the workpiece.

In each of the above embodiments, the aerosol sprayer 5
It is also possible to stop the operation using a timer or the like and automatically send hot air into the processing chamber 2 to promote the vaporization of the solvent such as water in the aerosol on the surface of the processing object 17. You can also take out items and put them in a separate dryer to dry them. Furthermore, as shown in FIG. 5, a turret type system can be used for automatic processing. That is, in FIG. 5, 20 is a rotating shaft, 21 is four movable tables protruding horizontally from the rotating shaft 20, 22 is a processing chamber, and 23 is a drying chamber. Place an object on it, rotate the rotating shaft 20, and move it to the processing chamber 22 and drying chamber 2 in order.
3 for a certain period of time, then taken out and processed automatically.

In the above embodiment, compressed air is sent by a compressor to atomize the coating solution into an aerosol consisting of a large number of fine particles, but the method is not limited to this method. Alternatively, an aerosol consisting of a large number of fine particles can be sprayed from a solution using any other suitable method.

〔Effect of the invention〕

Generally, aerosols with a particle size of 100 μm or less, particularly 10 μm or less have very good diffusibility and vaporization properties, but they also have a property of being difficult to adhere to the object to be treated, so-called poor wettability. In order to obtain a uniform coating film in a small amount by utilizing the diffusivity and vaporization properties of this aerosol, it is necessary to create a stable supersaturated state.

Therefore, in the present invention, the pressure inside the processing chamber is reduced to below atmospheric pressure before spraying the aerosol, and the aerosol is sprayed in this state, thereby further increasing the dispersibility of the aerosol within the processing chamber and instantly spreading it to every corner. When the aerosol is continued to be sprayed in this manner, the concentration of the aerosol per unit volume increases and the aerosol is diffused to every corner of the processing chamber in a supersaturated state. As a result, the aerosol penetrates to every corner of the surface of the object to be processed, which has complex irregularities in the processing chamber, and when the aerosol comes into contact with this surface, it is quickly adsorbed or attached. Since the adsorbed or adhered aerosol water and other solvents are small in particle size, they immediately vaporize. Therefore, even if the workpiece has a complex surface, the aerosol can evenly penetrate and be adsorbed or adhered to every corner of the workpiece, and compared to conventional methods, the amount of application can be adjusted to a much smaller degree, and therefore the surface of the workpiece can be The film formed can also be made as thin as desired.

Furthermore, in the case of conventional coating liquids with high viscosity, it was difficult to generate aerosols consisting of fine particles, but according to the method of the present invention, the pressure in the processing chamber is predetermined, so a normal generator can be used. It is possible to generate an aerosol consisting of very fine particles.

This invention also applies surface modifiers such as antistatic agents, colorants, This coating method can be used for various coating solutions such as adhesive coating, metal surface treatment, and food additive coating, and it is possible to control the application of these coating solutions in minute amounts.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional side view of the apparatus used in the method of the present invention, FIG. 2 is a vertical cross-sectional front view of the same, and FIG. 3 is a graph showing the atmospheric pressure inside the processing chamber and aerosol spray chamber in the method of the present invention. FIG. 4 is a longitudinal sectional front view of another embodiment of the apparatus used in the method of the present invention, and FIG. 5 is a configuration diagram showing the apparatus used in the method of the present invention in a turret type state. In the figure, 1 is the main body of the device, 2 is the processing chamber, 3 is the opening/closing door, 4 is the aerosol spray room, 5 is the aerosol sprayer, 6 is the tank, 12 is the exhaust duct, 14 is the exhaust slit, and 15 is the pressure reducing device. be.

Claims (1)

[Claims] 1. The object to be treated is placed in a sealed processing chamber, and a coating liquid such as a surface modifier is converted into an aerosol consisting of many fine particles and transferred into the processing chamber. This aerosol is diffused to a supersaturated state, and A coating liquid for a surface modifier, etc., which is characterized in that the process chamber is depressurized at least before the aerosol is sprayed, in a method of adsorbing or adhering an aerosol to an object and forming a film made of aerosol components on the surface of the object. Application method.