JP7262122B2 - Release agent layer forming method - Google Patents

Description

TECHNICAL FIELD The present invention relates to techniques for forming a layer of a release agent on a target surface , and in particular to preventing the release agent from being splashed when the release agent is sprayed onto the target surface , and The present invention also relates to a technique for making it difficult for a release agent to drip from its target surface, thereby increasing the coating thickness and thus the coating amount of the release agent at the same time.

Conventionally, in order to repaint the surface of structures such as buildings (houses, buildings, etc.), civil engineering structures (bridges, etc.), ships, vehicles (automobiles, trains, etc.), airplanes, etc., it has already been coated on the surface. A type of application has been performed in which the existing coating is stripped from the surface of the structure and then a new coating is applied over the same surface of the structure.

Here, as a method for stripping the existing coating film, there are a physical method and a chemical method, as described in Patent Document 1, for example. In the physical method, workers use hand tools such as scrapers, electric or rotating tools such as wire brushes, and stripping machines such as high-pressure water jets to strip the existing paint film from the structure.

In contrast, the chemical method is a method in which a release agent containing a drug is applied to the existing coating to dissolve or swell the existing coating, thereby peeling the existing coating from the structure. This method is also referred to as a wet coating removal method using a coating remover, that is, a wet stripping method, as described in Patent Document 1, for example.

There are various demands for the wet stripping method. For example, requests for stripping agents to have less adverse effects on the environment (enhancement of environmental responsiveness), requests for stripping agents to have less adverse effects on workers' health (prevention of workers' health hazards), There is a demand for high efficiency when workers perform the stripping work (improving the efficiency of stripping work by workers), and a demand for a stripping agent that has a high ability to strip existing coatings (improved stripping performance of the stripping agent). do.

Regarding the wet stripping method, Patent Document 1 describes the film thickness (hereinafter, " For the purpose of increasing the thickness of the coating film, a surfactant is added to the release agent as a foaming agent before dipping the release agent, and the release agent is stirred in that state to form a coating on the release agent. It discloses a technique for mixing minute air bubbles. If dipping increases the coating thickness of the release agent that is applied onto the existing coating film and increases the amount of coating, there is a possibility that the demand for more efficient stripping work and improved stripping performance will be met.

Further, Patent Document 2 discloses a technique using an airless spray coating machine in order to expand the coating area of the release agent. However, Patent Document 2 does not disclose or suggest that it is useful to use an airless spray coating machine to increase the coating thickness of the release agent.

JP-A-62-20575 Japanese Patent No. 6442101

Against the background of the above-described prior art, the present inventor has made the above-mentioned four demands, namely, the demand for improving the environmental response capability, the demand for preventing health hazards to workers, the demand for improving the efficiency of peeling work, and the In order to simultaneously achieve at least two of the desire to improve the release performance of the release agent, it is necessary to prevent the release agent from scattering when the release agent is applied, and to prevent the release agent from scattering on the surface of the existing coating film. It has been found that it is important to simultaneously increase the coating thickness and thus the amount of the release agent applied without dripping the release agent from the existing coating.

The inventors of the present invention have found that the wet-type release agent application technology should prevent the release agent from scattering when the release agent is applied, and prevent the release agent applied on the surface of the existing coating film from dripping from the existing coating film. We conducted research and development to make it possible to maximize the coating thickness of the release agent and increase the coating amount, and by extension, the coating amount, at the same time.

Against the background of these circumstances, the present invention provides a technique for forming a layer of a release agent on a target surface , which prevents the release agent from scattering when the release agent is sprayed onto the target surface , and It is an object of the present invention to provide a release agent coated on a surface which makes it difficult for the release agent to drip from the target surface and simultaneously increases the coating thickness and thus the coating amount of the release agent. It is.

To solve the problem, according to one aspect of the present invention, there is provided a method for forming a release agent layer comprising a liquid release agent applied in a foamed state onto a target surface, comprising:
An airless spray gun having a nozzle is used to pressurize the stripping agent itself to propel the stripping agent from the nozzle, thereby breaking the stripping agent into droplets that impinge on the target surface. In the injection step, the release agent is injected with an injection pressure of 30-60 kg/cm ² in a state having a viscosity of 5-16 Pa s (20 ° C.) before injection;
an applying step of applying the jetted release agent onto the target surface, wherein the plurality of droplets of the release agent impinge on the target surface during the application, thereby causing the plurality of droplets to entraining air in the atmosphere to form bubbles, thereby depositing and fixing the plurality of droplets as a plurality of air bubbles on the target surface;
A release agent layer forming method is provided comprising:
According to one aspect of the invention, there is also provided a method of forming a release agent layer comprising a liquid release agent applied in a foamed state onto a target surface, comprising:
An airless spray gun having a nozzle is used to pressurize the stripping agent itself to propel the stripping agent from the nozzle, thereby breaking the stripping agent into droplets that impinge on the target surface. an injection process;
an applying step of applying the jetted release agent onto the target surface, wherein the plurality of droplets of the release agent impinge on the target surface during the application, thereby causing the plurality of droplets to respectively entraining air in the atmosphere to foam, thereby depositing and fixing the plurality of droplets as a plurality of air bubbles on the target surface.
Further, according to one aspect of the present invention, there is provided a method for wet stripping an existing coating film from a structure using a stripping agent, comprising:
The release agent is a high-viscosity one having a viscosity higher than 0.1 Pa s,
The method is
By using an airless spray gun having a nozzle, the release agent itself is pressurized to spray the release agent from the nozzle, whereby the release agent is divided into a plurality of droplets and collides with the coating surface. an injection step to
A coating step of coating the ejected release agent onto the coating film surface, wherein the plurality of droplets of the release agent collide with the coating film surface during the coating, thereby causing the plurality of liquids to each of the droplets entrains air in the atmosphere to be foamed, whereby the plurality of droplets are adhered and fixed as a plurality of air bubbles on the surface of the coating film. be.

The present invention provides the following aspects. Each aspect is divided into sections, each section is numbered, and the numbers of other sections are referred to as necessary. This is to facilitate understanding of some of the technical features that can be employed by the present invention and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following aspects. should not be interpreted as That is, it should be construed that the technical features described in the present specification, which are not described in the following aspects, are appropriately extracted and employed as the technical features of the present invention.

Furthermore, it should be noted that stating each paragraph in a format that refers to the numbers of other paragraphs does not necessarily prevent the technical features described in each paragraph from being separated and independent from the technical features described in other paragraphs. It should be construed that the technical features described in each section can be made independent as appropriate according to their nature.

(1) A method for wet stripping an existing coating film from a structure using a stripping agent,
By using an airless spray gun having a nozzle, the release agent itself is pressurized to spray the release agent from the nozzle without using compressed air, thereby breaking the release agent into a plurality of droplets. an injection process;
A coating step of coating the ejected release agent onto the coating film surface, wherein the plurality of droplets of the release agent collide with the coating film surface during the coating, thereby causing the plurality of liquids to each droplet entraining air in the atmosphere to form a foam, whereby the release agent is applied onto the coating surface in a foamed state;
and a peeling step of physically peeling the existing paint film softened by the peeling agent from the structure after a required time has passed since the completion of the coating.

(2) The coating stripping method according to item (1), wherein the stripping agent has a high viscosity.

(3) The coating stripping method according to item (1) or (2), wherein the stripping agent is an aqueous stripping agent emulsion in which the main component and water are emulsified using a surfactant.

(4) The method for stripping a coating film according to item (1) or (2), wherein the stripping agent is a solvent-based stripping agent.

(5) applying the release agent to the coating surface such that the foamed release agent has a plurality of bubbles having an average diameter in the range of about 0.1 mm to about 0.5 mm; The method for stripping a coating film according to any one of items (1) to (4), which is applied on top.

(6) In the coating step, the release agent is applied to the coating film surface such that the average coating thickness of the coating film formed by applying the release agent to the coating film surface is about 1 mm. The method for stripping a coating film according to any one of items (1) to (5), which is applied on top.

(7) The coating step is performed so that the coating film formed by applying the release agent on the coating film surface has an average coating thickness in the range of about 2 mm to about 5 mm. The method for stripping a coating film according to any one of items (1) to (5), wherein a release agent is applied onto the surface of the coating film.

(8) In the coating step, the coating film formed by applying the release agent on the surface of the coating film has a larger coating thickness as the surface roughness of the existing coating film is smaller. The method for stripping a coating film according to any one of items (1) to (7), wherein the stripping agent is applied onto the surface of the coating film.

(9) In the injection step, the release agent is pressurized and injected from the nozzle with an injection pressure having a height that varies according to the viscosity of the release agent and the amount of the release agent discharged from the nozzle ( 1) A method for stripping a coating film according to any one of items 1 to 8.

(10) the release agent is volatile,
The coating film peeling method further comprises
After the application of the release agent is completed, the coating film surface is wrapped with a protective sheet that is impermeable to the release agent, whereby the vaporized gas generated from the release agent is released from the coating film surface to the atmosphere. including a wrapping process that prevents
The paint film peeling method according to any one of items (1) to (9), wherein the peeling step includes a step of peeling the protective sheet from the existing paint film after the required time has elapsed.

(11) The spraying step does not include the step of contacting the release agent with a flow of compressed air to atomize the release agent on the principle of spraying, and furthermore, before spraying the release agent from the nozzle, the The method for stripping a coating film according to any one of items (1) to (10), which does not include the step of foaming the stripping agent.

FIG. 1 is a system diagram conceptually representing an exemplary airless applicator used to implement a coating stripping method according to an exemplary embodiment of the present invention. FIG. 2 is a table showing the composition and operating temperature of each of a plurality of types of release agents or removers selectively used in the airless applicator shown in FIG. FIG. 3 is a process diagram showing an exemplary preparatory process in the coating film peeling method. FIG. 4 is a process diagram showing an exemplary construction process in the coating film peeling method. FIG. 5 is a diagram conceptually showing temporal changes in properties of the remover ejected from the nozzle of the airless spray gun shown in FIG. FIG. 6 is a diagram showing test results of coating properties of a remover applied on an existing paint film according to an embodiment of the present invention, in comparison with a comparative example.

A more specific exemplary embodiment of the present invention will be described in detail below with reference to the drawings.

An exemplary embodiment of the present invention relates to a wet stripping method for stripping an existing paint film from a structure (or structure) using a stripping agent (hereinafter also referred to as "remover"). Specifically, the wet stripping method is a foaming type airless coating stripping method in which a stripping agent is applied onto an existing coating film by foaming airless coating (airless spraying, airless spraying) and then stripped.

One example of the foaming type airless coating and peeling method is a method of applying a high-viscosity release agent onto an existing coating film by foaming airless coating and peeling.

Here, "high viscosity" means viscosity higher than the viscosity limit (for example, 0.1 Pa·s) at which general coating is possible, for example, when expressed in terms of paint viscosity. For example, "high viscosity" means a viscosity equivalent to gel coat paint (3 Pa s) or higher, or a viscosity equivalent to mayonnaise (23 ° C) (8 Pa s) or higher. may mean.

Another example of the foaming-type airless coating and peeling method is a method of applying a high-viscosity, emulsified release agent to an existing paint film by foaming-type airless coating and peeling. One example of a highly viscous, emulsified release agent is the first remover shown in FIG. 2, as described below.

The foaming type airless coating and peeling method described above (hereinafter referred to as "this peeling method") includes a foaming type airless coating step S201 as a chemical peeling step and a physical A peeling step S203 as a physical (mechanical) peeling step is included as a plurality of steps that are performed in that order.

FIG. 1 conceptually shows a system diagram of an exemplary airless applicator 10 used to perform the foaming type airless applicator step S201 described above.

The airless applicator 10 includes a tank 30 for storing a stripping agent 20 to be applied on the existing coating 14 in order to remove the existing coating 14 from the structure 12 by a wet method, and an airless pressure-feeding pump 40 (pumping machine). , an airless spray gun (hereinafter simply referred to as “spray gun”) 50 , and an air compressor 60 as a drive source for the force feed pump 40 .

Specifically, the air compressor 60 applies a high pressure to a pressure chamber 76 located behind a plunger or piston, which will be described later, thereby causing a discharge chamber (high viscosity to be discharged) located in front of the plunger or piston. is used to pressurize the chamber 80 into which the release agent 20 is pumped from the tank 30 .

The airless spray method using the spray gun 50 will be described later in detail with reference to FIG. In this method, the release agent 20 is made into droplets by colliding with it.

The tank 30 is connected to the supply port 72 of the compressing pump 40 via the hose 70 . The supply port 72 is fluidly connected to the discharge port 80 . The air compressor 60 is connected via an air hose 74 to a pressurizing chamber 76 of the pressure feed pump 40 . The spray gun 50 is connected via a high pressure hose 78 to the discharge chamber 80 of the pressure pump 40 . In the airless applicator 10, the hose 70 constitutes a supply line, the air hose 74 constitutes a compressed air line, and the high pressure hose 78 constitutes a pumping line.

The spray gun 50 pressurizes the release agent 20 itself by the plunger or piston without directly contacting the release agent 20 with compressed air to spray the release agent 20 from a nozzle, thereby spraying the release agent 20 into a plurality of nozzles. droplets.

In the spray gun 50, the pressure acting on the release agent 20 (for example, the injection pressure described later) is usually about 80-200 kg/cm ² , but in the present embodiment, it is set to 30 kg/cm 2 as described later. -40 kg/cm ² , which is lower than the normal value.

The spray gun 50 may employ any of a diaphragm type, a plunger pump type using a plunger, or a piston pump type using a piston as a method for discharging the release agent 20 as a material from the nozzle of the spray gun 50. However, if the release agent 20 has a high viscosity, it is desirable to adopt a plunger pump type or a piston pump type.

In addition, since the spray gun 50 has a low injection pressure as described above, the method of feeding the release agent 20 as a material into the discharge chamber in the spray gun 50 is a pressure feed type (the release agent 20 is added). Instead of pressing and extruding), a gravity method (using gravity to spray the release agent 20) or a blow-up method (using an air flow to blow up and spray the release agent 20) may be employed. However, a pumping method may be adopted.

Regardless of which method is adopted, the spray gun 50 is configured to have a main body portion 90 and a nozzle tip 92 detachably attached to the main body portion 90 . Body portion 90 is configured to include a grip 94 that is grasped by an operator and a trigger 96 that is operated by the operator.

The nozzle tip 92 has a nozzle through which the release agent 20 is injected. The cross-sectional shape of the nozzle can be, for example, circular, elliptical, or slit-shaped. In this embodiment, the cross-sectional shape of the nozzle is elliptical, and the equivalent diameter of the nozzle is 0.59 mm (within the range of 0.4-0.8 mm). Here, the "equivalent diameter" means the outer diameter of a circular area having the same area as the opening area of the nozzle opening.

The discharge amount of the release agent 20 from the spray gun 50 (also referred to as the discharge amount, defined as, for example, the weight of the release agent 20 discharged from the nozzle per certain period of time) and the spray pattern depend on the shape of the nozzle.

In this embodiment, the target spraying pattern of the release agent 20 from the elliptical nozzle of the spray gun 50 is, for example, when viewed from the side (direction perpendicular to the long axis of the cross-sectional shape of the elliptical nozzle), It has an isosceles triangle shape (fan shape) that widens in the spray direction, and the triangle has a height (spray distance) of about 25 cm and a base length (pattern width) of about 15 to about 20 cm. be.

Furthermore, in the present embodiment, when the elliptical nozzle is employed, the injection amount is 1490 mL/min when the injection pressure is 60 kg/cm ² , and the injection pressure is 30-40 kg/cm ² . At that time, the ejection volume is 750-1000 mL/min.

Features of Spray Gun 50

The spray gun 50 applies pressure to the release agent 20 itself to forcibly eject the release agent 20 from a nozzle without relying on air blowing.

To explain the principle of droplet formation of the release agent 20 by an airless spray method using the spray gun 50, as shown in FIG. 5, the release agent 20 is first sprayed as a liquid film from a nozzle at high pressure. The leading edge of the liquid film collides with the surrounding still air, which gradually slows down the leading edge of the liquid film. On the other hand, since the pressure for ejecting the release agent 20 is constant, the liquid film is wavy. As the corrugated liquid film travels through the still air, it is resisted by the still air, and the corrugated liquid film breaks up into a plurality of portions aligned in the direction of its travel.

After that, each split liquid film extends in a direction intersecting the traveling direction, and forms an uneven string so as to repeat concave portions and convex portions in the extending direction.

The uneven string-like portion is then divided into a plurality of droplets aligned in the direction in which it extends, thereby forming droplets of the release agent 20 .

By the way, since the spray gun 50 directly sprays the release agent 20 at high pressure, the amount of the release agent 20 scattered is smaller than that of the air spray gun, and the coating efficiency (for example, the total weight We of the sprayed release agent 20 is Of the sprayed release agent 20, the ratio of the amount W of the portion (excluding the scattered portion) applied onto the existing coating film 14) is high.

That is, since the spray gun 50 applies the release agent 20 as droplets without using air, the amount of the release agent 20 atomized and scattered in the air is small, and there is no health hazard to the environment and workers. In addition, the coating efficiency (for example, coating efficiency) of the release agent 20 is high.

Furthermore, since the release agent 20 can be applied while replenishing the release agent 20 to the spray gun 50, it is suitable for streamlining the stripping operation.

Since the spray gun 50 can apply the release agent 20 onto the existing coating film 14 at a higher pressure than the air spray gun, a thick film of the release agent 20 can be formed on the existing coating film 14 .

However, since the spray gun 50 ejects a larger amount of the release agent 20 than the air spray gun, the release agent 20 applied to the existing coating film 14 tends to drip unless additional measures are taken. .

Therefore, in the present embodiment, some countermeasures are added in order to improve the coating properties (fixing properties, adhesion properties, etc.) of the release agent 20 onto the existing coating film 14 .

(1) Foaming of release agent 20

According to experiments by the present inventor, the higher the injection pressure of the release agent 20 from the spray gun 50 (for example, the higher the pressure acting on the spray gun 50 from the air compressor 60), the more the release agent 20 is injected from the spray gun 50. It has been found that the cross-sectional diameter (dispersion diameter) of the spray pattern (eg conical) decreases with increasing velocity.

As the jetting speed increases, the impact energy when each droplet collides with the existing coating film 14 increases, and each droplet becomes finer due to the collision, and the total number of droplets increases. The surface area of the droplet as a whole, that is, the contact area with still air increases. The droplets thereby entrain more static air and foam. As a result, each droplet becomes finer, thereby forming a larger number of air bubbles in the release agent 20 as a whole.

On the other hand, in the release agent 20 having the same coating thickness, the greater the number of air bubbles, the lighter each air bubble becomes and the more difficult it is for each air bubble to flow over the existing coating 14 due to its own weight. As a result, it is presumed that the adhesion of the release agent 20 to the existing coating film 14 was improved, thereby increasing the coating thickness of the release agent 20 on the existing coating film 14 . In addition, the thicker the coating thickness of the release agent 20, the more the amount of the release agent 20 applied to the existing coating 14 (also referred to as the coating amount, for example, the amount of the release agent 20 applied per certain area (or certain time). (defined as weight) increases.

Experiments conducted by the present inventors have revealed that the injection pressure is preferably in the range of 30-60 kg/cm ² or 30-40 kg/cm ² . The numerical value is that the pattern in which the release agent 20 is sprayed from the spray gun 50 is the above-mentioned target spray pattern, and the existing coating is obtained without sufficiently atomizing the release agent 20 from the spray gun 50 (without atomizing). It is desirable to set so that it reaches above the membrane 14 .

(2) Increased viscosity of release agent 20

In general, when applying a high-viscosity release agent, unlike when using a low-viscosity release agent, if the release agent coating requires a thick film, the release agent will flow through the coating. Prevents drooping.

Experiments by the present inventors have revealed that the higher the coating viscosity of the release agent 20 is, the better the adhesion of the release agent 20 onto the existing coating film 14 is.

Further, experiments by the inventors of the present invention have revealed that it is desirable that the paint viscosity of the release agent 20 is as high as about 5 to about 16 Pa·s (20° C.).

(3) High emulsification of release agent 20

According to experiments conducted by the present inventors, the higher the emulsification degree of the release agent 20, the greater the number of bubbles generated in the release agent 20 by collision with the existing coating film 14, and the finer the bubbles. The fact that the adherence of the release agent 20 thereon is improved has been found.

In accordance with this finding, the release agent 20 employed an emulsion, ie, a water-based release agent (eg, the first remover in FIG. 2).

However, according to experiments by the present inventors, even if the release agent 20 is a non-emulsion, that is, a solvent-based release agent (for example, the second to fourth removers in FIG. 2), the coating thickness of the release agent 20 can be , i.e., using an air spray gun or by brushing, resulted in a thicker coating.

<Component Configuration of Release Agent 20>

The release agent 20 contains a main component, an adjuvant, and a thickener regardless of the type.

The main component contains an organic solvent in order to swell the existing coating film 14 and make it easier to peel off from the surface of the structure 12 . Examples of organic solvents include alcohol-based high boiling point solvents, ester-based organic solvents, and heterocyclic organic solvents.

Auxiliary agents exist for stabilizing the properties of the release agent 20, and include, for example, aromatic hydrocarbon solvents, terpenes, and the like.

The thickening agent exists so that the release agent 20 can be applied on the existing coating film 14 in a predetermined coating amount and is difficult to drip, and examples thereof include silicate compounds and organic bentonite.

<Variation of composition of release agent 20>

As shown in FIG. 2, in this embodiment, there are four types of removers 20 that can be applied onto the existing coating film 14 by the spray gun 50, such as first to fourth removers.

Among them, the first remover is a water-based remover (emulsion), while the second to fourth removers are solvent-based removers (non-emulsion).

In addition, the first and second removers exhibit normal reactivity and are recommended for use in hot periods where the average temperature is above about 10°C, whereas the third remover is recommended for use when the average temperature is below about 10°C. It exhibits normal reactivity even at low temperatures, and is recommended for use.

Since the fourth remover contains dichloromethane, safety control measures are required to prevent health hazards to workers, but it dries more quickly than other removers and exerts a strong peeling power. It is recommended that this fourth remover be used for partial repair.

1. Solvent remover

It contains an organic solvent as a main component (20-90%), and contains auxiliary agents, thickeners, etc. as auxiliary components.

2. Water-based remover

It contains an organic solvent as a main component (30-50%), and contains auxiliary agents, thickeners, etc. and water (35-50%) as auxiliary components.

Water-based strippers are generally less hazardous than solvent-based strippers.

The water-based release agent is an emulsion obtained by emulsifying the main component and water using a surfactant.

<Foam-type airless coating and peeling method>

The foaming type airless coating and peeling method according to this embodiment has a preparation step S100 shown in FIG. 3 and a construction step S200 shown in FIG. 4 so as to be performed in that order.

<Preparation process>

As shown in FIG. 3, first, in step S101, an operator investigates the existing coating film 14 to be removed. Specifically, existing coating film factors such as the material, coating thickness, and surface properties of the existing coating film 14 and structure factors such as the structure and shape of the structure 12 are investigated.

Next, in step S102, the operator selects the construction timing for peeling off the existing coating film 14. FIG. Once the construction period is selected, the average temperature of the environment at that construction period is predicted. That average temperature is referenced to determine which of the four removers described above is best.

Subsequently, in step S103, the operator selects peeling conditions. Specifically, one of the first to fourth removers in FIG. .

Furthermore, the number of times the stripping operation using the stripping agent 20 is repeated is determined according to factors including the investigated coating thickness. Further, the coating amount of the release agent 20 in each stripping operation is determined based on the aforementioned existing coating film factor and/or structure factor.

Further, the amount of the release agent 20 to be discharged from the spray gun 50 is determined according to the determined application amount, and depending on the circumstances, the nozzle tip 92 to be used this time is selected.

Furthermore, according to the viscosity of the release agent 20 this time and the amount of the release agent 20 discharged from the nozzle, the injection pressure when the spray gun 50 pressurizes the release agent 20 this time and injects it from the nozzle is determined. .

<Construction process>

As shown in FIG. 4, first, in step S201, the operator applies the above-described foaming type airless coating method to the existing coating film 14 .

The foaming type airless coating method includes a preparation step in which the operator prepares or procures the release agent 20 this time and puts it into the tank 30, and the operator starts the pressure pump 40, thereby and a pumping step of pumping the current release agent 20 from the tank 30 to the spray gun 50 in an airless state.

In the foaming type airless coating method, the operator holds the spray gun 50 and points it toward the target, that is, the existing coating film 14, and pulls the trigger 96 in that state, thereby ejecting the release agent 20 from the spray gun 50. It has an injection step of dividing into droplets and injecting them toward the target.

The jetting process does not involve contacting the release agent 20 with a stream of compressed air to atomize the release agent 20 on the principle of atomization; Does not include the step of foaming.

The foaming type airless coating method further includes a coating step in which an operator applies the jetted release agent 20 onto the surface of the existing coating film 14 .

In the coating process, the plurality of droplets of the release agent 20 collide with the surface of the existing coating film 14 during the coating, thereby causing the plurality of droplets to entrain air in the atmosphere and foam. Thereby, the release agent 20 is applied on the surface of the existing coating 14 in a foamed state.

In one example, the step of applying removes the release agent 20 from an existing coating such that the foamed release agent 20 has a plurality of bubbles having an average diameter in the range of about 0.1 mm to about 0.5 mm. It is carried out by coating on the surface of membrane 14 .

In another example, the step of applying the release agent 20 is such that the average coating thickness of the coating formed by applying the release agent 20 onto the surface of the existing coating 14 is about 1 mm. is applied onto the surface of the existing coating 14 .

In yet another example, the coating step is performed by applying the release agent 20 onto the surface of the existing coating 14 so that the average coating thickness of the coating is in the range of about 2 mm to about 5 mm. , the release agent 20 is applied over the surface of the existing coating 14 .

In either example, the existing coating 14 is swelled and softened by the release agent 20 , the adhesion to the surface of the structure 12 is reduced, and as a result the existing coating 14 is lifted off the surface of the structure 12 .

Next, in step S202, after the application of the release agent 20 is completed, the operator wraps the surface of the existing coating film 14 with a protective sheet impermeable to the release agent 20, thereby removing the release agent 20 ( If it has volatility), it prevents the vaporized gas generated from the surface of the existing coating film 14 from being released to the atmosphere. The protective sheet is, for example, a flexible polyethylene sheet, polypropylene sheet, or the like.

According to experiments conducted by the present inventors, as an effect of the lapping, release of vapor (vaporized gas) from the stripping agent 20 applied on the existing coating film 14 is prevented, whereby about 90% of the vapor is absorbed by the existing coating film. It was confirmed that it penetrated into 14 and the efficiency of the peeling work was promoted.

Subsequently, in step S203, after a required time (for example, 16 to 48 hours) has elapsed since the coating was completed, the operator peels off the protective sheet from the existing coating film 14 to remove it. After that, a worker physically peels and removes the existing coating film 14 , which has been lifted from the surface of the structure 12 by the peeling agent 20 , which has been lowered in adhesive strength.

To physically strip the existing coating 14 from the structure 12, the operator may use a scraper as a hand tool.

Furthermore, a wire brush (e.g., a cup-shaped wire brush) as an electric rotating tool is used to remove the paint film residue that is part of the existing paint film 14 remaining on the surface of the structure 12 after the first stripping operation. ) or an air grinder may be used.

Since this removal operation places a heavy burden on the operator, it is important that the electric rotary tool is as lightweight as possible and that the peeled coating film residue does not scatter. Therefore, it is desirable that the electric rotating tool be small and have a rotating part that rotates at a lower speed than usual.

Further, if desired, the operator may additionally or alternatively use a high pressure washer to remove existing coating 14 and/or coating residue.

In addition, according to the present embodiment, in order to achieve the target coating thickness of the release agent 20, multiple coating operations were required when using a brush or roller, but the target coating thickness can be achieved only once. It can be realized by coating work, and work efficiency is improved.

Furthermore, in the present embodiment, the release agent 20 is applied inline from the installation location (the location where the main body of the airless applicator 10 excluding the spray gun 50 in FIG. 1 is fixedly installed) (the main body and the work Locations, spray guns 50 and connected to each other by a continuous pumping line 78) can be delivered to the work location.

Specifically, the body of the airless applicator 10 (particularly, the pressure feed pump 40) and the spray gun 50 are connected to each other by a hose (line) 78 that serves as both a pressure transmission path and a material supply path. . As a result, unlike the case of air coating (spray coating), it is possible to connect the main body (particularly, the force-feeding pump 40) and the spray gun 50 to each other by both independent pressure transmission paths and material supply paths. becomes unnecessary.

As a result, the release agent 20 can be reliably delivered to the spray gun 50. Specifically, the release agent 20 is unexpectedly delivered while the release agent 20 is being delivered from the main body to the spray gun 50. This eliminates the possibility that the release agent 20 leaks to the work floor or the like and that part is contaminated with the release agent 20.例文帳に追加

<Paintability test>

Types of release agent 20 used in coating test

The type of release agent 20 used in the coating property test is the first remover (high viscosity emulsion) shown in FIG. One specific example of the first remover has the following composition.

Moisture: 40-50% by weight
Alcohol solvent: 40-50% by weight
Petroleum solvent: 1-5% by weight
Surfactant: 1-5% by weight
Thickener: 1-5% by weight
Rust preventives: Less than 1% by weight Waxes: Less than 1% by weight

Moreover, the specific example has the following properties.

Appearance: White or pale yellow viscous liquid Viscosity: 5-16 Pa s (20°C)

Example

260 g of the release agent 20 was airlessly applied to a 500 x 500 mm steel plate for painting as a test piece using a spray gun 50, so that the test piece had an application amount of 1.0 kg/m ² (application density, spray density). realized.

After the application, the test piece was hung vertically, and after 5 minutes the test piece was photographed in order to observe how the release agent 20 dripped. The photograph is pasted on the upper part of FIG.

Comparative example

260 g of the release agent 20 was applied to a 500 x 500 mm steel plate for painting as a test piece using a brush (not shown), whereby the test piece had an application amount of 1.0 kg / m ² (application density, spraying density) was realized.

After the application, the test piece was hung vertically, and after 5 minutes the test piece was photographed in order to observe how the release agent 20 dripped. The photograph is attached at the bottom of FIG.

contrast observation

In the example, dripping of the release agent 20 (for example, traces of flow of the release agent 20, unexpected behavior of the release agent 20 caused by gravity, such as falling of the release agent 20) could not be observed at all. Moreover, the surface of the release agent 20 applied to the test piece was smooth.

As is clear from the photograph at the top of FIG. 6, in the example, it was confirmed that the release agent 20 applied to the test piece did not run off from the test piece at all.

Furthermore, the average coating thickness of the release agent 20 adhered to and fixed to the test piece without dripping from the test piece (for example, the coating thickness when applied only once without overcoating) is from about 2 mm to about It was also confirmed that it was within the range of up to 5 mm.

Further, it was also confirmed that the release agent 20 in its foamed state on the specimen had a plurality of bubbles with an average diameter in the range of about 0.1 mm to about 0.5 mm.

On the other hand, in the comparative example, dripping (or flow, flow line) of the release agent 20 was observed over the entire test piece. In addition, on the surface of the release agent 20 applied to the test piece, a streaky uneven pattern was present due to material flow.

As is clear from the photograph at the bottom of FIG. 6, in the comparative example, it was confirmed that part of the release agent 20 applied to the test piece flowed down from the test piece.

In addition, in order to confirm the effect of the present embodiment, the present inventors tested a steel tower as a building having a surface on which the release agent is difficult to spread due to its complicated shape. A peeling operation was actually performed using the foaming type (foaming promotion type) airless coating and peeling method according to the embodiment. As a result, it was confirmed that the stripping work was ensured, that is, the existing paint film was stripped to every corner, and that the stripping work time was shortened.

Additionally, in the above description of the present embodiment, the phenomenon in which the release agent 20 foams occurs during the process in which the release agent 20 sprayed from the spray gun 50 flies in still air. A plurality of droplets split from the release agent 20 due to the collision do not become air bubbles, and when they collide with the existing coating film 14, the plurality of droplets become air bubbles and the release agent 20 bubbles on the existing coating film 14. It was explained as a mode to do.

However, in the process in which a plurality of droplets of the release agent 20 fly in still air, at least some of the droplets collide with the still air to form air bubbles. do not exclude.

Although some of the exemplary embodiments of the present invention have been described in detail above with reference to the drawings, these are examples, and a person skilled in the art can It is possible to implement the present invention in other forms with various modifications and improvements based on knowledge.

Claims (1)

A method of forming a release agent layer comprising a liquid release agent applied in a foamed state onto a target surface, the method comprising:
An airless spray gun having a nozzle is used to pressurize the stripping agent itself to propel the stripping agent from the nozzle, thereby breaking the stripping agent into droplets that impinge on the target surface. In the injection step, the release agent is injected with an injection pressure of 30-60 kg/cm ² in a state having a viscosity of 5-16 Pa s (20 ° C.) before injection;
an applying step of applying the jetted release agent onto the target surface, wherein the plurality of droplets of the release agent impinge on the target surface during the application, thereby causing the plurality of droplets to each entraining air in the atmosphere to foam, thereby depositing and fixing the plurality of droplets as a plurality of air bubbles on the target surface.

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