JPH01180271A - Method and device for preventing skinning of nozzle or the like - Google Patents

Abstract

PURPOSE:To prevent skinning to be generated on a nozzle, etc., in a two-fluid spraying method for a liquid adhesive agent, etc., by introducing mist consisting of a solvent in a circuit of a compressed gas and spraying the same from the spray nozzle by a gaseous mixture with the compressed gas. CONSTITUTION:A supply port 18 to be introduced with the mist Sa of the solvent S is internally provided on the supply circuit 8 of the compressed air CA which is spray air in the two fluid spraying method for the liquid adhesive agent, etc., for example, an emulsion adhesive agent. The solvent S to be used at this time is the same solvent as the solvent contained in the emulsion adhesive agent or analogous thereto. The compressed air CAs contg. the fine particles of the solvent is ejected from an ejection port 4M at the terminal of an ejection passage 4 according to this constitution. The fine particles of the solvent strike against the peripheral part in the aperture 5M of the ejection port 5 for the emulsion adhesive agent L and moisten said part by sticking thereto. Namely, the residue Z of the emulsion adhesive agent to be ejected is diluted and the adhesion thereof is obviated, by which the skinning is prevented.

Description

[Detailed description of the invention] [Industrial application field] The invention relates to the application of adhesives or coatings.

The present invention relates to a method and device for preventing the occurrence of skinning phenomenon in the vicinity of a nozzle and/or its surroundings.

[Conventional Techniques] Conventionally, room temperature drying type coating agents and adhesives, particularly thermoplastic solvent type and emulsion type coating agents containing solvents, have been widely used.

These coatings and adhesives generally have a lower viscosity when applied than hot-melt adhesives, and because they contain solvents, a thin film can be obtained in the end.
It is characterized by the fact that it can be done with simple equipment, and it also leads to a reduction in material costs. The above-mentioned solvent-type and emulsion-type coating agents and adhesives (hereinafter collectively referred to as emulsion adhesives) are:

When the solvent evaporates, it solidifies, resulting in what is commonly called a skinning phenomenon, and cleaning them requires a lot of time, and improvements to these problems have been desired for some time. In particular, emulsions of vinyl acetate or ethylene-vinyl acetate copolymers exhibit strong adhesion to paper and have better heat resistance than general hot melt adhesives. On the other hand, the solvent used is water, but if a skin is applied near the nozzle or the like, cleaning with water becomes impossible, and cleaning with an organic solvent with higher dissolving power is required.

Furthermore, in general, cheap and simple methods such as air spray guns have been the mainstream for applying emulsion adhesives in the packaging field. Furthermore, with recent advancements in automation, the need for labor-saving has further increased, and in particular, the emulsion adhesive mentioned above is prone to skin formation, which progresses and completely solidifies the nozzle, making it impossible to apply. If this happens, it can be inspected in the post-process, but if it is incomplete, the coating amount will change, but it is difficult to detect, and this poses a serious defect in quality, making it difficult to automate them. This has caused a huge hindrance.

[Points to be solved while trying to solve the problem] As mentioned above, the motivation of the present invention was to try to prevent the skinning phenomenon that occurs on the nozzle, especially when emulsion adhesive is discharged from the nozzle. .

By preventing the above-mentioned skin formation, 1. It is possible to operate continuously for a long time without monitoring or cleaning during operation, which greatly improves efficiency and reduces overhead costs. You can make a contribution.

[Means for solving the problem of interstices] The gist of the invention is to provide a compressed gas, ie, spray air or pattern air, in the supply circuit of a two-fluid spray nozzle.

A fume body made of the same or similar solvent contained in the emulsion adhesive to be sprayed is introduced and mixed, and with the spray action thereof, the area around the nozzle is moistened and washed with the solvent, and the area around the nozzle is moistened and washed. This method and device are characterized by preventing the occurrence of skinning of an emulsion adhesive.

There are three types of methods of the present invention. Each item will be explained separately.

First Method This method is for two-fluid spraying and is a particular invention of the present invention. Referring to FIG. 1, the present method is to supply four vapors (Sa) of solvent (S) into the compressed air (CA) supply circuit (8) in the conventional two-fluid spray method. That is, compressed air (C
A) on the supply circuit (8) and on the gun (1) body (2
) of the solvent (S) as close as possible to the
a) A supply port (18) for introducing the liquid is provided inside.

The reason why such a close location is desirable is that when passing through a complicated circuit, the fine particles of the solvent in the atomized body aggregate into droplets.
This is because when sprayed, the coating film surface becomes diluted and becomes rough.

In this way, compressed air (CAs) containing solvent particles is
) is ejected from the ejection port (4M) at the end of the ejection passage (4).

As shown in Fig. 2, the emulsion adhesive (L) hits the periphery of the opening (5M) of the spout hole (5), and the fine particles of the solvent adhere to the area, moistening the area. A thin film of solvent is formed, thereby diluting the ejected emulsion adhesive residues (Z) and eliminating their adhesion, as shown in FIG.

In this way, residues such as emulsion adhesives are removed.

Even particles cannot adhere to the vicinity of the opening (5M) of the nozzle (5). Therefore, these residues grow, narrowing or blocking the eruption hole (5), or forming a skin (Z).
It will no longer be possible to do anything like that. In other words, the nozzle is constantly cleaned and kept clean, so there is no need for maintenance and the number of man-hours is greatly reduced.

However, the amount of solvent consumed in the above case is extremely small.

According to the results of experiments, it has been confirmed that the amount of adhesive, etc. can be less than 2% (weight ratio).

In addition, the target adhesive or coating agent is preferably a solvent-type or an emulsion-type adhesive, but in the current experiment, especially for emulsion-type adhesives, the solvent is water or water containing less than 5% Remarkable effects have been recognized for those containing alcohol-based solvents.

Furthermore, the consumption of the solvent used in the present invention is small, and experiments have shown that less than 2% by weight of the adhesive or coating agent is sufficient.

Next, there are various patterns regarding the introduction of the atomized body of the solvent according to the present invention into the compressed gas circuit, i.e., the timing of their outflow and their duration, and representative examples thereof will be given below. Please refer to Figure 4.

"A" pattern During continuous or intermittent discharge of emulsion adhesive, the opening and closing of the emulsion adhesive (L), compressed gas (CA), solvent N, seismic body (Sa), etc. always take the same step. It is.

The "B" pattern emulsion adhesive (L) and the compressed gas (CA) take the same step, but only the solvent fumes (Sa) are shorter and more intermittent within their ejection time.

In dispensing emulsion adhesive (L) by continuous opening and closing of "C" pattern, compressed gas (CA) and solvent fumes are added for a short period of time (a, b) before and after the dispensing time, i.e. for a longer period of time. This is a pattern in which the bodies (Sa) are ejected at the same time and at the same time.

When discharging the emulsion adhesive (L) by intermittent opening and closing in the "D" pattern, the compressed gas (CA) is spouted out for a longer period of time (plus the time before and after the discharge time) as in the "C" pattern above. However, the solvent fume (Sa) is
It is introduced into the compressed gas (CA) for a relatively short period of time (c, d) before and after the "closing" point (T1) of the compressed gas (CA).

In the discharge of emulsion adhesive (L) by intermittent opening and closing of the "E" pattern, for a relatively short time (e, f) before and after the "close" point (T2) of the discharge, the compressed gas (CA) and The smoke body (Sa) is ejected in the same step, that is, at the same time and at the same time.

In the discharge of the emulsion adhesive (L) by the "F" pattern intermittent opening and closing, at a time (g) slightly delayed from the "close" point (T3) of the discharge, the compressed gas (CA) and the solvent vapor (
Sa) erupts at the same time, at the same time, and for a relatively short period of time.

Second Method Although the above description has been made in the case of two-fluid spraying, the method of the present invention can also be applied in one-fluid spraying, i.e., airless spraying. It may use air as a supplement in airless spraying. It is also called airless air spray or air mix spray. In the case of airless spraying, air is blown from outside the nozzle in order to correct the spray pattern. For example, as shown in FIG. 9, what is called a tail (T) is generated at both ends of the spray pattern (sp) due to airless spraying. Generally, this is difficult to atomize, that is, it is often in the form of droplets. To eliminate this, the industry generally uses air spraying similar to pattern air. However, the disadvantage of these methods is that compressed air is ejected toward the nozzle hole.

The flow of air dries the residue of the ejected liquid in and around the orifice of the airless nozzle, making it easy for so-called skinning phenomenon to occur. In the first place, airless spray uses relatively high liquid pressure (20 kg/aJ-150 kg/m), so if there is a slight amount of skin, the effect of this will be small and spraying can continue, but the nozzle If the residue and the skinned emulsion adhesive adhering to the area are ejected together, they will adhere to the coating surface in the form of foreign matter commonly called lumps. These become fatal coating defects in coatings. In this case, the above problem can be solved by using the method of the present invention. Please refer to FIG. 5, a solvent fume (Sa) or a compressed gas (Sa)
CA) using an airless spray nozzle (68).
A gas outlet (76) provided at an appropriate position on the outer circumference of the
M), the above-mentioned tail (T) can be eliminated by blowing toward the tip of the nozzle and operating the pattern air. At the same time, the fine particles of the above-mentioned atomized material adhere to the vicinity of the periphery of the nozzle, condense and liquefy to form a liquid film, which prevents the residue of the ejected liquid from adhering and dissolves, thereby preventing the occurrence of skin formation. be.

Third Method This method is a further development of the method of the present invention for airless spray described above and applied to an extrusion nozzle. Airless spray nozzles and extrusion nozzles are basically the same.

Please refer to FIG. 5 as above. That is, the emulsion adhesive (L) is discharged from the nozzle (68), and the atomized material (Sa) or a mixture of it and compressed gas (CA) is ejected from the periphery of the nozzle (68) through a plurality of ejection ports (68M). )
The liquid is ejected toward the vicinity of the nozzle hole. The solvent in the fume aggregates and forms a film around it.

This dissolves the residue and prevents skinning from occurring. The ejection of the above-mentioned atomized body and compressed gas is not the above-mentioned spray air or pattern air, but is used exclusively for cleaning the nozzle.

Although the extrusion nozzle described above is of a round shape, the extrusion nozzle is also applicable to a slit nozzle. The tip of the slit nozzle is provided with two linear lips facing each other, and the atomized material is sprayed from outside on both sides of these lips. However, as a practical matter, it is also possible to spray only one lip, as shown in FIG.

In the same slit nozzle (@5), the coating progress direction (
The rear side opposite to F), that is, the rear side of the lip of the slit (97
), compressed air containing solvent fumes (Sa) (
CAs) can be sprayed. The reason is the same lip (intimidation 7)
This is because if there is a residue on the surface, it will leave a trail on the surface of the coating film.

- There is a slot nozzle which is similar to the slit nozzle described above, and the present invention is also applied to this nozzle. Further, this is a so-called contact coating method in which the coating is often applied while contacting the slot (I') surface.

The method of the present invention can also be applied to a pole type transfer nozzle which is a contact type and an extrusion type. As shown in FIG. 6, the nozzle is a Pole pen type discharge nozzle. The lip that holds the pole (86) in place (
By spraying atomized solvent from the outside around the outer periphery of 85) to moisten the area around the lip, skinning can be prevented and a clean transfer can always be performed.

Next, the apparatus according to the present invention will be explained. This device can also be divided into three types according to the three methods mentioned above.

First device, see FIG. 1, operating air (OA) and emulsion adhesive (L) supplied to the gun (1), compressed gas (
The piping (36, 46, 8) such as CA) is almost the same as the conventional one. The difference is, as shown in the same figure,
A solvent mist (
A supply port (18) for Sa) is provided.

The opposite side of the supply (18) of the vapor (Sa) is naturally connected to the vapor generator via piping. In the figure, a smoke generator fffi (11) is shown as the generator. The smoke image generator is also called an aerosol generator, in which a required liquid is placed in a sealed container (12) and gas is injected from the bottom of the liquid through a nozzle hole (14).
When the bubbles (sb) rise and burst at the liquid surface, the gas film scatters and becomes fine particles that are dispersed in the gas, producing a vapor of them.

Naturally, in the present invention, since a solvent is used as the liquid, a vapor of the solvent is obtained.

In addition, a liquid heating type (such as a humidifier), a spray type Venturi tube type, an ultrasonic type, etc. can also be used as a device for obtaining a solvent vapor.

In the above explanation, the supply port (18) for the solvent vapor was provided in the compressed gas pipe (8).
18) is desirably provided downstream of the compressed gas on-off valve (24).The reason is that if there are obstacles on the path of the M seismic body, they may aggregate and become droplets as mentioned above. Because there is.

Furthermore, the supply port for the above-mentioned atomized material can also be provided in the compressed gas passage (4) in the gun body (2) (51) or in the air cap (53).

The second device is equipped with a patterned air outlet on the outside of the tip of the airless spray nozzle. There are various positions, directions, and sizes of the nozzles depending on the requirements for pattern control, but FIG. 5 shows, as a basic explanation, two nozzles provided on both sides. Pattern air is compressed gas (A)
In the gas supply pipe (75), there is a vapor (S).
The supply port (73) of a) is provided. On the opposite side of the supply port is the smoke generator i! , ($1), and the other side of the compressed gas supply piping is connected to the CA source via a solenoid valve.
and electrical wiring are connected to the controller. Other than that, the liquid (L) supply device and the gun operation air supply device are the same as those of the conventional ones, and therefore their explanation will be omitted.

Third device Instead of the pattern air piping in the second device described above, it is provided with a plurality of jet ports for a dedicated atomizer or a mixture of the same and compressed gas around the outer periphery of the extrusion nozzle. The principle is the same as the second device described above, so the explanation will be omitted.

[Effects] As described above, the present invention prevents the skinning phenomenon that occurs on the nozzle when spraying or discharging an emulsion-type or solvent-type adhesive or coating agent,
There are some things that greatly contribute to improving work efficiency.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the first method which is a specific invention of the present invention. FIGS. 2 and 3 are explanatory diagrams of the operation of the above method. FIG. Fig. 5 is a side sectional view of the structure of an airless spray nozzle according to the second method of the present invention and an extrusion nozzle according to the second method. Fig. 6 is a time graph showing the same invention as above. Fig. 7 is a side sectional view when the above invention is applied to a slit nozzle Fig. 8 is a side sectional view when the above invention is applied to a slot nozzle Fig. 9 is a conventional airless Diagram explaining the state in which the tail phenomenon occurs in the spray pattern by the spray nozzle. Explanation of the main symbols.

Claims (1)

[Claims] 1. In a two-fluid spray method for liquid adhesives or coatings, a fume consisting of a solvent is introduced into a compressed gas circuit, and a gas mixture with the compressed gas is passed through a two-fluid spray nozzle. A method for preventing skinning of a nozzle, etc., which comprises spraying to prevent skinning from occurring on the nozzle and/or its vicinity. 2. The adhesive or coating agent is an emulsion type adhesive, and the solvent thereof is water or water containing 5% or less of an alcoholic solvent, and furthermore, water contains 5% or less of an additive. A method for preventing skinning of a nozzle, etc., according to claim 1. 3. Skin coating for nozzles, etc. according to claims 1 and 2, characterized in that the amount of solvent in the atomized body to be introduced is 2% or less by weight relative to the adhesive or coating agent. How to prevent it. 4. In continuous or intermittent discharge of adhesives or coatings, the introduction of atomized solvent, i.e., their outflow time, is carried out continuously for the same or necessary time within the jetting time of the compressed gas. A method for preventing skinning of a nozzle, etc., as set forth in claims 1, 2, and 3, characterized in that: 5. In continuous or intermittent discharge of adhesives or coatings, the introduction of atomized solvent consisting of a solvent, that is, the time for their outflow from the supply port, is carried out intermittently for short periods within the time for spouting compressed gas. A method for preventing skin formation of a nozzle, etc., as set forth in claims 1, 2, 3, and 4, characterized in that: 6. During the intermittent discharge of the adhesive or coating agent, the introduction of the atomized solvent, that is, the time for their outflow from the supply port, covers the time before and after the discharge time of the adhesive or coating agent, at the same time as the compressed gas is jetted out. A method for preventing skin formation of a nozzle, etc., as set forth in claims 1, 2, and 3, characterized in that the method is carried out. 7. In the intermittent discharge of adhesives or coatings, the introduction of atomized solvent consisting of a solvent, that is, the outflow time from the suction port, is carried out for the required time before and after the end of spouting of compressed gas. A method for preventing skinning of a nozzle, etc., as set forth in claims 1, 2, and 3, characterized in that: 8. In the intermittent discharge of adhesive or coating agent, the introduction of atomized gas consisting of solvent, that is, the time for their outflow from the supply port, is necessary together with the jetting of compressed gas before and after the end of discharge of adhesive or coating agent. A method for preventing skin formation of a nozzle, etc., as set forth in claims 1, 2, and 3, characterized in that the method is carried out for a period of time of . 9. The introduction or outflow time of the fume consisting of the solvent in the intermittent discharge of the adhesive or coating agent is carried out at the desired timing with the ejection of the compressed gas when the discharge of the adhesive or coating agent is stopped. Claims 1 and 2 are characterized in that
A method for preventing skinning of a nozzle, etc., as described in Section 3. 10. A nozzle characterized in that a supply port for a vapor made of a solvent is provided in the piping of a circuit for supplying compressed gas to a two-fluid spray nozzle, and the supply port is connected via piping to the above-mentioned vapor generation device. Anti-skinning device such as. 11. A skinning prevention device for a nozzle or the like as set forth in claim 10, wherein the supply port for the atomized material is provided in a passage for compressed gas in the gun. 12. A skinning prevention device for a nozzle or the like as set forth in claim 10, wherein the supply port for the atomized material is provided in an air cap. 13. The skinning prevention device for a nozzle or the like as set forth in claim 10, wherein the vapor generating device is of a spray type, a bench lily type, a liquid heating type, or an ultrasonic type. 14. In an airless spray method for liquid adhesives or coatings, airless spraying is carried out while spraying a vapor consisting of a solvent or a mixture of the vapor and compressed gas toward the tip of an airless spray nozzle, and A method for preventing skinning of a nozzle, etc., characterized by preventing skinning that occurs at or near the nozzle. 15. A method for preventing skinning of a nozzle, etc. as set forth in claim 14, which comprises supplying a vapor made of a solvent into a pattern air supply circuit in an airless spray nozzle. 16. A plurality of smoke ejection ports are provided from the periphery of the airless spray nozzle toward the tip of the nozzle, and the smoke ejection ports are connected via piping to a vapor generation device made of a solvent. Anti-skinning device for nozzles, etc. 17. The skin of a nozzle, etc. according to claim 16, characterized in that a vapor supply port is provided in the pattern air supply piping in the airless spray nozzle, or in a particularly provided compressed gas supply piping. Anti-tension device. 18. In a method for discharging a liquid adhesive or coating agent from an extrusion nozzle, a vapor made of a solvent or a mixture of the vapor and compressed gas is sprayed toward the tip of the nozzle, and the area near the nozzle is A method for preventing skinning of nozzles, etc., characterized by preventing skinning from occurring. 19. A nozzle characterized in that a plurality of atomizer outlets are provided from the periphery of the extrusion nozzle toward the tip of the nozzle, and the atomizer outlets are connected via piping to an atomizer generator made of a solvent. Anti-skinning device such as. 20. A skinning prevention device for a nozzle or the like according to claim 19, wherein the extrusion nozzle is a slit nozzle or a slot nozzle. 21. A skinning prevention device for a nozzle or the like according to claim 19, wherein the extrusion nozzle is a pole type transfer nozzle or the like.