JPH0347552A - Coating method and apparatus - Google Patents

Abstract

PURPOSE:To prevent the clogging of a nozzle by emitting compressed air from the emitting orifice in the vicinity of a liquid substance jet orifice and spraying a liquid substance to the vicinity of an inside wall on the inside thereof in a spray pattern. CONSTITUTION:A liquid substance is injected from a jet orifice 12 and compressed air passes through a communication passage to be injected from the emitting orifice 14 provided to the vicinal part of the liquid substance jet orifice 12 and the injected compressed air surrounds the periphery of the jet orifice 12. Further, a cover 6 provided with an opening part 20, which is slightly larger than the spray pattern of the liquid substance, permitting the spray pattern injected from the jet orifice 12 to pass without generating disturbance is filled with the compressed air emitted from orifice 14 and said compressed air is injected to the outside from the opening part 20. The carrier gas from a carrier gas orifice 18 is mixed into the spray of the liquid substance passing through the opening part 20 of the cover 16. By this method, good painting work can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method and apparatus for coating liquid materials, and more particularly to a spray coating method and apparatus suitable for liquid materials that harden in the presence of a curing accelerator. .

(Prior Art and its Problems) In recent years, plastics have been widely used as materials for automobile parts and home appliances from the viewpoint of weight reduction and rust prevention.

In coating plastics, it is strongly desired to form a coating film at a low temperature from the viewpoint of heat resistance, and a catalytic vapor mixed coating system is used as one of the coating methods.

The above coating system is a method in which a two-component urethane resin paint is rapidly cured by the catalytic action of amine vapor, and the main components are polyol and incyanate. A two-component urethane resin paint was mixed and the viscosity was adjusted with a solvent. The paint is atomized using mixed air containing amine vapor generated by an amine vapor generator using a general air spray gun, and then sprayed onto the object to be coated.

The sprayed paint is rapidly cured by the catalytic action of the amine, forming a urethane resin coating.

The formed coating film is usually post-heated at 40 to 100°C and cured and dried. Although this catalytic vapor mixed coating system achieves the purpose of low-temperature curing to a large extent, there is a demand in the market for further low-temperature (normal temperature) rapid curing. When a liquid material that hardens in about a minute is coated with this coating system, a carrier gas flow containing a curing accelerator flows into and comes into contact with the nozzle of the spray device. The paint may harden rapidly, causing clogging of the liquid at the spout, such as nozzle clogging, or clumping of cured paint that has accumulated at or near the nozzle and contaminates the sprayed paint. It was found that it was not possible to form a stable coating film because it caused spots in the coating film.

The present inventor previously filed a patent application for a coating device that does not have the above problems and has good coating workability even when coating a liquid material that hardens quickly at room temperature in the presence of a curing accelerator. It was proposed in No. 1-14099. This is a device in which a carrier containing a curing accelerator mixes a gas flow into a spray of liquid material, and this mixture is applied to the object to be coated to form a coating film. A compressed gas discharge port is provided, and the compressed gas jetted from the discharge port covers the area around the spouted liquid material in the vicinity of the jet port, creating a kind of air curtain. However, depending on the conditions, the carrier gas containing the curing accelerator may flow back around the jet nozzle, preventing the nozzle from clogging and preventing the formation of lumps. was not perfect.

(Means for Solving the Problems) In view of the above-mentioned situation, the present inventor has developed a method for preventing nozzle clogging and for applying a liquid material that hardens rapidly at room temperature in the presence of a curing accelerator. As a result of intensive research into a coating method and coating device that can completely prevent the occurrence of spots and have good coating workability, the present invention has been arrived at.

That is, in the present invention, a liquid material that hardens in the presence of a hardening accelerator is sprayed, a carrier gas containing the hardening accelerator is mixed into the sprayed body of the liquid material to form a mixture, and the mixture is coated with the mixture. In the method of applying the liquid to an object to form a film, compressed gas is discharged from a discharge port near the spout of the liquid, and the liquid is applied to the spout and the opening of a cover covering the spout. The present invention provides a coating method characterized in that the compressed gas is sprayed in a spray pattern having an outer surface near the inner side of the inner wall, and the compressed gas is caused to flow out of the cover through the opening.

Also, the present invention provides a coating device suitable for the above-mentioned coating method, an ejection port for ejecting a liquid material that hardens in the presence of a curing accelerator to form a predetermined spray pattern of the liquid material, and a curing accelerator. A coating device is equipped with a carrier gas outlet for ejecting a carrier gas containing gas and mixing the carrier gas into the liquid material, comprising: an outlet for discharging compressed gas; and a cover for covering the outlet and the outlet. characterized in that the cover has an opening having an inner wall near the outer side of the spray pattern of the liquid ejected from the outlet, and the carrier gas port is located on the outer side of the cover. The present invention provides coating equipment.

In the method of the present invention, any liquid that can be cured and dried in the presence of a curing accelerator can be used as long as it can be cured and dried in the presence of a curing accelerator.
The method of the present invention is highly effective for liquid materials that harden and dry quickly, for example, within 30 minutes at a temperature of about 30.degree. Examples of such liquid materials include two-component urethane resin paints made of polyol resins such as acrylic polyols, polyester polyols, and epoxy polyols using amines as curing/accelerating agents and polyisocyanate crosslinking agents.

The curing accelerator used in the method of the present invention may be any substance as long as it can accelerate the curing of the liquid, and in particular can accelerate curing rapidly.
It is also preferable to use one that can be easily vaporized. Examples of amines that can be used as curing accelerators for two-component urethane resin paints include triethylamine, dimethylethylamine, triallylamine, tributylamine, dimethylbenzylamine, dimethylcyclohexylamine, dimethylethanolamine, diethylethanolamine, pyridine, -PhenylpropyJ reviridine, 2,4,6-collidine, quinoline, isoquinoline, N
- Mention may be made of tertiary amines such as ethylmorpholinmine.

Moreover, a paint using water vapor as a curing accelerator can also be used.

In the present invention, examples of the carrier gas containing the curing accelerator include air and inert gases such as nitrogen and carbon dioxide. The concentration of the curing accelerator in the carrier gas may be appropriately determined so as to exhibit the catalytic effect, but for example, when using an amine as the curing accelerator, it is usually 1 to 8000 pp.
More preferably, m is in the range of 1O to 4QOOppm.

In addition, in the method of the present invention, the compressed gas is injected from a discharge port near the spray port so that the curing accelerator does not come into contact with the spray port of the liquid material, and the spray device has an opening. The liquid material and compressed gas are ejected through the opening of the cover covering the discharge port. The compressed gas used may be compressed air or an inert gas such as nitrogen or carbon dioxide, and may be the same as or different from the carrier gas.

The cover is for preventing the carrier gas containing the curing accelerator from approaching the liquid material spout.

In order that the cover does not disturb the spray pattern (eg, conical shape) of the ejected liquid, the cover is placed outside the outer side of the spray pattern (eg, the side of the cone). In other words, the outer surface of the spray pattern
It is located near the inner side of the inner wall of the opening of the cover. If the cover is placed inside the spray pattern, the liquid may undesirably adhere to the cover, or the spray pattern may be disrupted, resulting in uneven density of the atomized liquid, resulting in improper coating.

Preferably, the cover is placed proximate the outer surface of the spray pattern. That is, it is preferable that the cover has an opening that follows the shape of the spray pattern and is slightly larger. By doing this,
The pressure inside the cover can be higher than the outside, and the carrier gas containing the curing accelerator can be effectively prevented from approaching the liquid material spout.

A space is defined by the outer surface of the spray pattern (for example, a conical shape), the inner wall of the cover (the surface facing the injection port and the discharge port), the spray having the injection port, and the spray having the discharge port. Ru.

By forming this space, the compressed gas discharged from the discharge port remains in this space, passes between the spray pattern and the inner surface of the opening of the cover, and exits to the outside. The presence of this space equalizes the pressure of the compressed gas exiting the outlet, thereby equalizing the flow rate of the compressed gas between the spray pattern and the inner wall of the cover opening in the circumferential direction. Ru.

Additionally, the flow of compressed gas between the spray pattern and the inner wall of the opening prevents liquid from coming into contact with the cover when the painting equipment is moved from side to side during normal painting operations. can be prevented.

As described above, by ejecting the liquid and compressed gas through the opening of the cover, it is possible to effectively prevent the carrier gas containing the curing accelerator from entering the inside of the cover. It is possible to prevent the carrier gas containing the curing accelerator from approaching the spout of the liquid material.

(Embodiment) Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings and FIGS. 1 to 3.

FIG. 1 shows a coating apparatus apparatus lO according to a preferred embodiment of the present invention.
FIG.

This coating device 10 has a structure in which the device proposed in the above-mentioned Japanese Patent Application No. 1-14099 is provided with a cover that covers the liquid material jetting port and the compressed gas discharge port.

To explain further, in FIG.
The compressed gas (for example, compressed air) passes through the compressed gas communication path and is injected from the discharge port 14 provided in the vicinity of the liquid material jet port 12, and the injected compressed air is Surround the area around exit 12. Further, the compressed air discharged from the discharge port 14 fills the cover 16, which is provided with an opening 20 that is slightly larger than the spray pattern of the liquid material, through which the spray pattern discharged from the jet port 12 passes without disturbance. It is spouted out from the opening 20.

A carrier gas containing a curing accelerator sprayed from the outer carrier gas port 18 is mixed into the spray of liquid material that is ejected from the ejection port 12 and passed through the opening 20 of the cover 16, and this mixture is applied to the coating material. It applies to objects, forms a coating, and hardens rapidly.

The vicinity of the ejection port 12 is such that compressed gas is ejected from the ejection port 14 and covers the ejection port 12 and the ejection port I4.
Because of the cover 16, the space inside the cover 16 is filled with compressed gas, and the pressure is higher than the outside.
Even if the carrier gas containing the curing accelerator is injected from the outer carrier gas port 18, the carrier gas will not enter the inside of the cover 16, much less the carrier gas will not come into contact with the ejection port 12. Therefore, even if the coating is applied for a long time, the nozzle is not clogged or the coating film is blistered, and a good coating operation can be performed.

Note that the direction in which the compressed gas is discharged from the discharge port 14 is not particularly limited, and it may be discharged so that the inside of the cover 16 has a higher pressure than the outside, but it is necessary to do so so as not to disturb the spray pattern of the paint. For this reason, it is preferable that the jetting ports 12 be arranged in a direction substantially parallel to the paint jetting direction, or in a direction tilted by 0 to 80' from the parallel direction to a direction perpendicular to the paint jetting direction.

On the other hand, the direction in which the carrier gas containing the curing accelerator is discharged from the outer carrier gas port 18 is such that the angle θb (Fig. 1) with respect to the plane perpendicular to the spray direction of the paint is 0 to 80 degrees. is preferred.

FIG. 2 is a front view of the vicinity of the liquid jet nozzle of the apparatus of the present invention, and the center of the cover 16 is an opening 20. In this embodiment, the spray pattern is an elliptical cone and its cross-sectional shape is an ellipse, so the opening 20 of the cover 16 has an elliptical shape, as shown in FIG. In this way, the shape of the opening 20 of the cover 16 follows the cross-sectional shape of the spray pattern. For example, in the case of a general conical spray pattern, the cross-sectional shape is a circle. The shape of the opening of the cover 16 is also made circular accordingly.

The shape and size of the opening are determined by the nozzle shape, spray angle, etc. The smaller the opening is, the easier it is to maintain a high pressure inside the cover with compressed air, and the smaller the intrusion area is, the more difficult it is for the carrier gas to enter, which is preferable. However, if the opening is too small, the spray pattern from the nozzle from the spout 12 will hit the area around the opening. , which disrupts the spray pattern and prevents proper painting.

FIG. 3 is a front view of the coating apparatus shown in FIG. 1 with the cover 16 removed.

The number of the compressed gas discharge ports 14 may be one, but it is preferable to provide a plurality of them or to form them in a ring shape so as not to cause uneven flow. In the illustrated example, 16 0.8-1 discharge ports are provided.

In addition, the carrier gas port for the carrier gas containing the curing accelerator is 1.
However, in order to uniformly mix the curing accelerator into the liquid spray, it is preferable to provide a plurality of them or to form them into a ring shape. In the illustrated example, the 2"- outlet is
We have set up 6 of them.

In order to improve the curing properties of a liquid, increase the concentration of the curing accelerator, increase the pressure of the carrier gas containing the curing accelerator, increase the number of discharge ports, and increase the curing accelerator. An effective measure is to increase the diameter of the carrier gas discharge port, and these measures may be taken as necessary.

An example of coating using the coating apparatus shown in FIG. 1 will be described below.

A two-component acrylic urethane resin paint that hardens rapidly at room temperature in the presence of an amine and is mainly composed of an acrylic polyol and a polyisocyanate cross-linking agent as a liquid product is viscous to a viscosity of 15 seconds/Ford Cup N004 with a solvent. Thereafter, a pressure of 100 kg/cm'' was applied to the paint using a plunger pump, and the paint was pumped to a spray gun.

Also, the air pressure compressed by the compressor is 0.3 kg.
/cm of compressed air was sent to the communication path of the discharge port 14.

Roughly air containing 2000 to 4000 ppm of dimethylethanolamine vapor, which is a curing accelerator, was applied as a carrier gas at a pressure of 0.5 kg/cm2, and the carrier gas 1
I sent it to the communication path of 8.

Note that the compressed air at a pressure of 0.3 kg/cm2 from the discharge port 14 was kept flowing regardless of the 0N-off (not shown) of the spray, while the carrier gas was tuned to the 0N-off of the spray. However, when the spray is on, the carrier gas is ejected, and when the spray is off, the ejection of the carrier gas is stopped.

The coating was applied at a paint discharge rate of 600 to 1200 cc/min to a coating film thickness of 50 to 100 μm.

Although the painting took about 30 minutes, there was no intrusion of amine vapor into the jet nozzle 12 and its surroundings, so there was no clogging of the nozzle, and there were no lumps, indicating good painting workability and the ability to spray liquid. Because a curing accelerator was mixed in, rapid curing was possible.

As mentioned above, the shape and size of the opening are determined by the shape of the nozzle (spray angle), etc. In this painting example, the spray pattern was determined with a coating discharge rate of 600 to 1200 cc/min and a spray distance of 300 mm. , 35
When using 0mm a-4 to 5mm b
- Good painting is possible with openings of 10 to 12 mm in size without any particular problems, and the finish is good (smoothness, sagging resistance)
A good coating film was obtained.

(Effects) According to the method of the present invention, even when a liquid material such as a paint that hardens rapidly in the presence of a curing accelerator is applied, no blisters will be generated in the coating film even if the nozzle is clogged. , it is possible to apply a liquid material that hardens rapidly, improving painting workability.

Furthermore, the apparatus of the present invention can be suitably used in the method of the present invention and exhibits good painting workability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the vicinity of a liquid material spouting port, showing an example of a coating apparatus used in the method of the present invention. FIG. 2 is a front view of the vicinity of the liquid material spout. FIG. 3 is a front view when the cover 16 in FIG. 2 is removed. 12... Liquid material spout, 14... Compressed gas discharge port, 16... Cover 18... Carrier gas port, Fig. 10-1\ 20 Fig. 3

Claims (1)

[Claims] 1. Spraying a liquid material that hardens in the presence of a hardening accelerator;
A method in which a carrier gas containing a curing accelerator is mixed into the spray of the liquid to form a mixture, and the mixture is applied to an object to form a film, the method comprising: The compressed gas is discharged from the discharge port, and the liquid material is sprayed in a spray pattern having an outer surface near the inner side of the inner wall of the discharge port and the opening of the cover covering the discharge port, and the compressed gas is A coating method characterized in that the coating is caused to flow out of the cover from the opening. 2. A jetting port that jets out a liquid material that hardens in the presence of a hardening accelerator to form a predetermined spray pattern of the liquid material, and a jetting port that jets out a carrier gas containing a hardening accelerator. A coating device equipped with a carrier gas port for mixing into the liquid, comprising a discharge port for discharging compressed gas, and a cover that covers the jet port and the discharge port, and the cover is arranged such that the gas is jetted from the jet port. 1. A coating device comprising: an opening having an inner wall near the outer side of a spray pattern of liquid material; and the carrier gas port is located on the outer side of the cover.