WO2019176741A1 - Coating method - Google Patents

Abstract

A purpose of the present invention is to provide a coating method and the like capable of reducing whitening of a coating film even when coating a high-viscosity paint using carbon dioxide as a diluent. The coating method according to one embodiment of the present invention comprises the steps of: mixing carbon dioxide with a paint to obtain a coating composition; spraying the coating composition to form a mist; and adhering the mist to an object to form a liquid film on the object, wherein the paint has a viscosity of 400 mPa·s or more at 20°C and 1 atm, the amount of carbon dioxide is 1.5 parts by mass or more based on 100 parts by mass of the paint, and when the temperature of the mist is denoted by T1 and the dew point of the environment around the mist is denoted by T2, T1 and T2 satisfy T1 - T2 ≥ 0.

Description

Painting method

The present invention relates to a coating method using carbon dioxide.

Many paints contain a certain amount of solvent in advance in order to reduce the viscosity of the paint. Further, in the process of preparing the coating composition, the paint is often diluted with a solvent. These solvents, known as volatile organic compounds (VOCs), can have an unfavorable impact on the environment, so it is possible to use paints that do not contain or contain small amounts of these solvents, ie high viscosity paints. preferable.

As a method that makes it possible to paint (coat) high-viscosity paints, a coating composition is prepared by mixing carbon dioxide with the paint, and the resulting coating composition is sprayed onto the object (carbon dioxide painting) Method) is known. In this method, carbon dioxide functions as a diluent and the viscosity of the paint is reduced to a sprayable level.

A number of techniques relating to coating using carbon dioxide have been developed, for example, as described in Patent Documents 1 to 6.

Japanese Patent No. 4538625 Japanese Patent No. 5429928 Japanese Patent No. 5429929 Japanese Patent No. 5660605 Japanese Patent No. 5568801 Japanese Patent No. 5608864

When a highly viscous paint was applied by a conventional carbon dioxide coating method, the coating film formed on the object sometimes whitened. The whitening of the coating film may impair the appearance and may deteriorate properties such as the strength of the coating film.

This invention is made | formed in view of the said subject, Even if it is a case where a highly viscous coating material is applied using a carbon dioxide as a diluent, the coating method which can reduce the whitening of a coating film is provided. For the purpose.

The inventors of the present invention have made extensive studies and found that carbon dioxide in the coating composition is vaporized by spraying the coating composition, so that the temperature of the mist generated by spraying is instantaneously reduced. The inventors have found that the whitening of the coating film can be reduced by setting the relationship between the temperature of the mist and the dew point of the environment around the mist within a certain range, and to complete the present invention. It came.

A coating method according to an aspect of the present invention includes a step of mixing a paint with carbon dioxide to obtain a coating composition, a step of spraying the coating composition to form a mist, and attaching the mist to an object. Forming a liquid film on the object, and the paint has a viscosity of 400 mPa · s or more at 20 ° C. and 1 atm, and the amount of carbon dioxide is based on 100 parts by mass of the paint. When the temperature of the mist is T ₁ and the dew point of the environment around the mist is T ₂ , T ₁ and T ₂ satisfy T ₁ −T ₂ ≧ 0.

The paint and the carbon dioxide can be mixed at a temperature and pressure at which the density of carbon dioxide is 0.7 kg / L or more.

The paint may contain 1% by mass or more of solvent with respect to the total amount of the paint.

The paint and the carbon dioxide can be mixed at a temperature and pressure at which carbon dioxide exists in a liquid state with a density of 0.7 kg / L or more.

The paint and the carbon dioxide can be mixed at a temperature below 60 ° C.

The coating method according to an aspect of the present invention includes a step of measuring the T ₁ and the T ₂ and a step of adjusting a mixing ratio of the carbon dioxide and the paint so as to satisfy T ₁ −T ₂ ≧ 0. And can be further provided.

According to the present invention, whitening of the coating film can be reduced even when a high viscosity paint is applied using carbon dioxide as a diluent.

It is a block diagram which shows one Embodiment of a coating device.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

A coating method according to an embodiment of the present invention includes a step of mixing a carbon dioxide with a paint to obtain a coating composition (mixing step), a step of spraying the coating composition to form a mist (spraying step), And a step of forming a liquid film on the object by attaching mist to the object (film forming process).

(1. Mixing process)
In this step, a coating composition is obtained by mixing paint and carbon dioxide.

<Paint>
The viscosity Va of the paint at 20 ° C. and 1 atm (0.1 MPa) is 400 mPa · s or more. The paint is not particularly limited as long as it has a viscosity Va of 400 mPa · s or more. The viscosity Va can be, for example, 20000 mPa · s or less, 3000 mPa · s or less, 2000 mPa · s or less, 1000 mPa · s or less, or 500 mPa · s or less. In the present specification, the viscosity Va is a value measured at a rotation speed of 3 rpm using a B-type viscometer. The density of the paint can be from 0.9 to 4.0 kg / L.

A paint having a high viscosity Va of 400 mPa · s or more usually contains substantially no solvent or a small amount in many cases. The term “substantially free of solvent” means that the solvent is not contained or is extremely small, for example, less than 1% by mass, 0.5% by mass or less, or 0.1% by mass or less based on the total amount of the paint. It means the case of containing the solvent. The solvent exists in a liquid state at 20 ° C. and 1 atm, and is generally added to the paint for the purpose of reducing the viscosity of the paint. When the paint contains a solvent (1% by mass or more), the allowable amount of the solvent is usually 90% by mass or less, 30% by mass or less, 25% by mass with respect to the total amount of the paint, although it depends on the type of the solvent. % Or less, 20 mass% or less, 15 mass% or less, 10 mass% or less, or 5 mass% or less.

The solvent is not particularly limited as long as it does not prevent dissolution of carbon dioxide in the paint. For example, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethyl diglycol acetate (EDGAc), n-butanol, diisobutyl ketone, toluene, acetic acid Butyl, ethyl acetate, isobutyl acetate, methyl ethyl ketone, propylene glycol monomethyl ether, ethylene glycol mono-n-butyl ether (butyl cellosolve), Solvesso 100 (S100) (trade name, manufactured by TonenGeneral Sekiyu KK), Solvesso 150 (S150) (TonenGeneral) So-called true solvents such as petroleum products, trade names), formamide, butyrolactone, propylene glycol, ethanol, methanol, isopropyl alcohol, dimethylform Numerous organic solvents such as highly polar solvents such as amide, acetonitrile, dimethyl sulfoxide, so-called weak solvents such as aliphatic hydrocarbons, gasoline, kerosene, coal tar naphtha, petroleum ether, petroleum naphtha, petroleum benzine, turpentine, mineral spirits Is exemplified. The solvent can be an organic solvent having a boiling point of 50 to 250 ° C. from the viewpoint of reducing the occurrence of defects in the coating film such as whitening and peeling.

The paint may be a solventless paint or an organic solvent paint. Examples of the paint include acrylic resin paint (for example, styrene acrylic resin paint), polyurethane resin paint (for example, acrylic urethane resin paint and polyester urethane resin paint), epoxy resin paint, polyester resin paint, alkyd resin paint, vinyl chloride Vinyl acetate copolymer resin paint (vinyl acetate resin paint), styrene butadiene rubber paint, amino resin paint, phenol resin paint, vinyl chloride resin paint, nitrocellulose resin paint, cellulose acetate butyrate resin paint, styrene resin paint, melamine urea Examples thereof include resin paints, Teflon (registered trademark) resin paints, silicon resin paints (for example, acrylic silicon resin paints and silicone urethane resin paints), polyethylene resin paints, and polypropylene resin paints. You may use these individually or in mixture of 2 or more types. The paint may be a one-component curable type or a two-component curable type.

The paint contains a film-forming component that is cured by a polymerization reaction and / or a crosslinking reaction. The film-forming component can contain a main agent and its curing agent. For example, a urethane resin coating contains a polyol such as acrylic polyol and polyester polyol and a curing agent thereof (for example, an isocyanate curing agent) as a film forming component, and is cured into a urethane resin such as an acrylic urethane resin and a polyester urethane resin. Become. In addition, the film forming component may contain an appropriate modifier together with the main agent and the curing agent. For example, a silicone-based urethane resin paint includes, as an example, a polyol and a diisocyanate, and a silicone compound reactive with these (for example, a diorganopolysiloxane having an alcoholic hydroxyl group at a terminal), and is cured to form a silicone-modified urethane resin. (Silicone urethane resin). Alternatively, the film-forming component can include a prepolymer (oligomer), a dilution monomer, and optionally a polymerization initiator or catalyst. For example, the acrylic resin paint can contain acrylate prepolymers such as epoxy acrylate, urethane acrylate, polyacryl acrylate, and polyester acrylate, an acrylate ester, and a photopolymerization initiator as a film forming component. UV) cure to acrylic resin. The film-forming component can be thermosetting or light (such as UV) curable.

The paint may further contain an additive as necessary. For example, additives such as pigments, pigment dispersants, ultraviolet absorbers, light stabilizers, leveling agents, adhesion promoters, rheology control agents, and the like that are usually added to paints may be included.

<Mixing conditions>
In order to spray a highly viscous paint, the amount of carbon dioxide needs to be 1.5 parts by mass or more with respect to 100 parts by mass of the paint, and is 2 parts by mass or more, 5 parts by mass or more, or 10 It can be greater than or equal to parts by mass. When the amount of carbon dioxide is 1.5 parts by mass or more with respect to 100 parts by mass of the paint, fine mist can be formed. Although depending on the type of paint, carbon dioxide of about 0.3 to 1.5 parts by mass can be dissolved in 100 parts by mass of the paint at 20 ° C. and normal pressure (0.1 MPa). . Therefore, when the amount of carbon dioxide to be mixed is less than 1.5 parts by mass, when the coating composition is sprayed from the spray nozzle, the carbon dioxide may not expand due to the change in the state of carbon dioxide. Fine mist may not be formed.

In order to spray a highly viscous paint, it is considered preferable to mix a large amount of carbon dioxide to reduce the viscosity of the paint, but according to the study by the inventors, a large amount of carbon dioxide is mixed. in the temperature T ₁ of the mist tends to be reduced, too it is not necessarily preferred to mix a large amount of carbon dioxide.

The amount of carbon dioxide is such that a dew point T ₂ in a mist temperature T ₁ and an environment around the mist (hereinafter, “environment” refers to an environment (gas atmosphere) around the mist) T It is determined so as to satisfy the relationship ₁ −T ₂ ≧ 0. As will be described later, since the mist temperature T ₁ decreases as the amount of carbon dioxide increases, the amount of carbon dioxide is set so that the mist temperature T ₁ does not become lower than the dew point T _{2 in the} environment.

Assuming that the above relationship is satisfied, the amount of carbon dioxide is, for example, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 25 parts by mass or less with respect to 100 parts by mass of the coating material. Or 20 parts by mass or less.

Also, it is preferable that the amount of carbon dioxide to be mixed does not exceed the solubility of carbon dioxide in the paint under the temperature and pressure conditions at the time of mixing. More preferably, the amount of carbon dioxide mixed is below the solubility of carbon dioxide in the paint. If the amount of carbon dioxide exceeds the solubility of carbon dioxide in the paint, a portion of the carbon dioxide cannot be dissolved in the paint, and the coating composition becomes a two-phase mixture. The coating composition is a two-phase mixture, that is, in the coating composition, the main phase (liquid) of the paint in which carbon dioxide is dissolved and the phase in which the concentration of the paint is lower than the main phase based on carbon dioxide ( Liquid, supercritical, or gas), in the subsequent spraying process, if the two phases are not sprayed in a sufficiently dispersed and mixed state, one phase is not sprayed and only the other phase is sprayed In some cases, it is difficult to stably (continuously) form the mist.

The paint and carbon dioxide have a density of carbon dioxide of 0.7 kg / L or more, 0.72 kg / L or more, 0.75 kg / L or more, 0.77 kg / L or more, 0.78 kg / L or more, 0.79 kg. / L or higher, 0.80 kg / L or higher, or 0.83 kg / L or higher. At a temperature and pressure at which the density of carbon dioxide is 0.7 kg / L or more, the density of carbon dioxide is close to the density of the paint, so that the paint and carbon dioxide are likely to be physically mixed and easily dissolved together. . If the paint and carbon dioxide are not sufficiently dissolved, a portion of the coating composition containing almost no carbon dioxide may be supplied to the nozzle. When a portion containing almost no carbon dioxide is discharged from the nozzle, the paint does not become mist and the spraying operation becomes intermittent. When the paint and carbon dioxide are sufficiently dissolved, continuous and stable spraying becomes possible. The paint and carbon dioxide may be mixed at a temperature and pressure at which the density of carbon dioxide is 1.1 kg / L or less. The paint and carbon dioxide may be mixed at a temperature and pressure at which carbon dioxide exists as a liquid. In this case, the paint and carbon dioxide are more likely to be physically mixed.

The mixing temperature is preferably less than 60 ° C, more preferably less than 30 ° C, still more preferably 10 ° C or more and less than 30 ° C, but is not limited thereto. When the paint is a two-component curable paint, when the temperature is lower than 60 ° C., the usable time (pot life) of the coating composition tends to be good.

The method of mixing is not particularly limited, and the mixing can be, for example, mixing by a line blend method using an in-line mixer.

The coating composition obtained by mixing paint and carbon dioxide contains paint and carbon dioxide. As described above, the carbon dioxide preferably has a density of 0.7 kg / L or more, and the amount of carbon dioxide is 1.5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the paint. Is preferred. The coating composition is preferably a one-phase mixture in which the total amount of carbon dioxide is dissolved in the paint.

(2. Spraying process)
In this step, the coating composition is sprayed to form mist. When the coating composition is sprayed, for example from a nozzle or orifice, the carbon dioxide in the coating composition released from the pressurized state is instantly vaporized and its volume expands significantly. Due to the energy generated by the expansion, the coating composition becomes a fine mist paint (mist). Carbon dioxide, in order to take the heat of vaporization from the coating composition during the vaporization, the temperature T ₁ of the mist is lower than the temperature of the coating composition just before spraying. The greater the amount of carbon dioxide contained in the coating composition (i.e., the amount of carbon dioxide to vaporize), the greater the heat of vaporization and the lower the temperature of the mist.

In the present embodiment, the mist temperature T ₁ and the dew point T ₂ in the environment around the mist satisfy the relationship of T ₁ −T ₂ ≧ 0. That is, in accordance with the dew point T _2, to set the temperature T ₁ of the mist so as to satisfy the relational expression. For this reason, whitening of a coating film can be reduced.

T ₁ and T ₂ are T ₁ −T ₂ > 0, T ₁ −T ₂ ≧ 0.5, T ₁ −T ₂ ≧ 1, T ₁ −T ₂ ≧ 2, T ₁ −T ₂ ≧ 3, T 1 The relationship ₁ −T ₂ ≧ 4 or T ₁ −T ₂ ≧ 5 can be satisfied. Temperature T ₁ of the mist, for example, by placing a thermometer into the mist can be directly measured. Also, approximate values of T _1, from the temperature of the spray just before the coating composition can be estimated by subtracting the temperature to decrease by vaporization of carbon dioxide. According to the study by the present inventors, the temperature of the mist decreases by 1 ° C. every time 1 part by mass of carbon dioxide is vaporized with respect to 100 parts by mass of the paint. Therefore, the approximate value of T ₁ may be estimated by subtracting the amount (parts by mass) of carbon dioxide with respect to 100 parts by mass of the paint from the temperature (° C.) immediately before spraying the coating composition. Dew point T ₂ in the environment, it can either be measured using a dew-point instrument can be calculated from the water vapor content or humidity in the environment.

The mist temperature T ₁ is preferably less than 60 ° C. When the paint is a two-component curable paint, if the temperature is lower than 60 ° C., the pot life of the coating composition tends to be good.

The temperature and pressure at the time of spraying may not be controlled positively, may be the same as the temperature and pressure at the time of mixing, or may be adjusted as appropriate. From the viewpoint of enabling spraying, the spray pressure is preferably 2 MPa or more or 5 MPa or more. The pressure in this specification is an absolute pressure (MPa).

In one embodiment of the present invention, the mixing step and the spraying step can be repeated.

In the coating method according to another embodiment of the present invention, the step of measuring the temperature T ₁ of the mist, the step of measuring the dew point T ₂ of the environment around the mist, and the obtained values of T ₁ and T ₂ And adjusting the amount of carbon dioxide and paint supplied to the mixer 8 so as to satisfy the relationship of T ₁ -T ₂ ≧ 0. Specifically, when T ₁ -T ₂ <0, the amount of carbon dioxide may be reduced and / or the amount of paint may be increased.

(3. Film formation process)
In this step, the mist formed in the spraying step is attached to the object to form a liquid film (paint film) on the surface of the object.

(4. Curing process)
The coating method of this invention can further be equipped with the process (curing process) which hardens | cures the liquid film formed in the target object by the film formation process, and forms a coating film. In this step, the paint film is cured to form a coating film. The curing method depends on the type of paint, but for example, the paint film can be cured by heating or active energy rays such as UV. The coating film formed by the coating method according to the present invention has reduced whitening.

(Coating equipment)
Said method can be performed using the coating device shown in FIG. 1, for example. The coating apparatus includes a paint tank 1, a high-pressure pump 2, a heater 3, a carbon dioxide cylinder 4, a cooler 5, a high-pressure pump 6, a heater 7, a mixer 8, and a nozzle 9. The paint stored in the paint tank 1 is pressurized to a predetermined pressure by the high-pressure pump 2, heated to a predetermined temperature by the heater 3, and then supplied to the mixer 8 (mixing unit). On the other hand, the carbon dioxide stored in the carbon dioxide cylinder 4 is cooled and liquefied by the cooler 5 and pressurized to a predetermined pressure by a high-pressure pump 6 (for example, a constant volume pump such as a plunger pump). The pressurized carbon dioxide is heated to a predetermined temperature by the heater 7 and then supplied to the mixer 8. The paint and carbon dioxide are mixed in the mixer 8 to form a coating composition. As the mixer 8, for example, an in-line mixer can be used. The coating composition thus prepared is sprayed through the nozzle 9 into the environment in which the object is arranged.

The pressure in the mixer 8 can be adjusted by the discharge pressure of the high pressure pump 2 and the high pressure pump 6. The temperature in the mixer 8 can be adjusted by the temperature of the paint heated by the heater 3 and the temperature of carbon dioxide heated by the heater 7. The amount ratio of paint and carbon dioxide can also be adjusted by the discharge amount of each pump and a flow rate control valve (not shown).

The coating apparatus is not limited to the apparatus shown in FIG. For example, in the apparatus shown in FIG. 1, the temperature during mixing is adjusted by the heaters 3 and 7 and the cooler 5, but these configurations are not essential. For example, instead of the heaters 3 and 7 and the cooler 5, a temperature adjusting unit such as a heat exchanger may be provided inside the mixer 8 to adjust the temperature during mixing. Moreover, in the apparatus shown in FIG. 1, although the pressure at the time of mixing is adjusted with the high pressure pumps 2 and 6, these structures are not essential. For example, instead of the high pressure pumps 2 and 6, the pressure during mixing may be adjusted by providing a pressure adjusting unit such as a pump or a pressure reducing valve in the mixer 8. Further, a temperature adjusting unit and / or a pressure adjusting unit may be provided on a line connecting the mixer 8 and the nozzle 9 to control the temperature and / or pressure during spraying.

Painting apparatus 1 includes a thermometer 20 for measuring the temperature T ₁ of the mist, and dew point meter 22 for measuring the dew point T ₂ of the environment, fed into the mixer 8 according to the value of T ₁ and T ₂ And a feedback unit 24 for adjusting the amount of carbon dioxide and paint to be applied.

As described above, in the coating method according to the present embodiment, the temperature T ₁ of the mist and the dew point T _{2 in the} environment satisfy the relationship of T ₁ −T ₂ ≧ 0. When T ₁ and T ₂ satisfy the relationship of T ₁ -T ₂ ≧ 0, whitening of the coating film formed by painting can be reduced. The present inventors presume this reason as follows.

If the temperature T ₁ of the mist is below the dew point T ₂ in the environment, the surface of the surface or during formation of the liquid film of the mist condensation, water is contained in the liquid film that is finally formed. In the present embodiment, since the paint has a high viscosity, the liquid film is cured while the water contained in the liquid film remains, and the water evaporates from the coating film after the liquid film is cured. Therefore, it is considered that bubbles are formed in the coating film, or traces of open bubbles resembling the armpit are formed on the surface of the coating film, which is one of the causes of whitening. In contrast, in the present invention, the temperature T ₁ of the mist are adjusted to the dew point T ₂ or more, the water derived from the water vapor in the environment is less likely contained in the coating, the coating The whitening of the film can be reduced.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

In the carbon dioxide coating apparatus as shown in FIG. 1, the paint is charged into the paint tank 1 so that the mixture ratio of the paint and carbon dioxide in the mixer 8 becomes the mixture ratio (composition) shown in Tables 2-7. The flow rates of the high pressure pumps 2 and 6 were set. The temperature Tm and pressure Pm in the mixer were adjusted to the temperatures and pressures shown in Tables 2-7. In Tables 2 to 7, the units of the amount of paint and carbon dioxide are parts by mass, and NV means the mass ratio of non-volatile components (film forming components etc.) in the paint, and when NV is not 100% The paint contains a solvent that dissolves the film-forming component. Table 1 shows the solvents contained in the paint. The acrylic resin paints in Tables 3 and 6 are both UV curable paints containing an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator.

The viscosity Va of the paints in Tables 2 to 7 was measured at a rotational speed of 3 rpm using a B-type viscometer VISCOMETER TVB-10 (manufactured by Toki Sangyo Co., Ltd.) in an environment of normal pressure (0.1 MPa) and 20 ° C. It was measured. In principle, the measurement was performed using a rotor having a rotor number of M1. When the measured value was out of the measured viscosity range of the rotor having the rotor number M1, the viscosity Va was measured using an appropriate rotor.

The viscosity Vm of the paint in Tables 2 to 7 is the viscosity of the paint under normal pressure and the same temperature condition as the mixing temperature Tm. The viscosity Vm was measured using TVB-10 in the same manner as the measurement of the viscosity Va.

The viscosities Vc of the coating compositions in Tables 2 to 7 were measured in-line using Proline Promass I 500 (manufactured by Endless Hauser).

A coating test was performed on the examples shown in Tables 2 to 7, and a paint film was formed on the surface of the object. In each example, the sprayed mist was observed visually, and whether the mist was stably formed and the state of the formed mist were evaluated. Thereafter, the examples shown in Tables 2 to 7 were cured by drying or heating the coating film, and it was evaluated whether or not whitening was observed in the formed coating film. However, for the examples using UV curable acrylic resin paints shown in Tables 3 and 6, the paint film was dried to evaporate the solvent, and then cured by UV irradiation. It was evaluated whether it was observed. The results are shown in Tables 2-7.

Regarding the evaluation of “whitening of the coating film”, “◯” and “X” in Tables 2 to 7 mean the following.
○: Whitening of the coating film was observed.
X: Whitening of the coating film was not observed.

Regarding the evaluation of “stable mist formation”, ○ and X in Tables 2 to 7 mean the following.
○: Mist was stably formed.
X: Mist formation was unstable. Sometimes mist was formed, and sometimes mist was not formed even when sprayed.

Regarding the evaluation of the “mist state”, “O”, “Δ”, and “X” in Tables 2 to 7 mean the following.
○: All mist particles were fine.
Δ: Most of the particles in the mist were fine, but large particles were slightly mixed.
X: No mist was formed, and the coating composition was released in a straight line like a water gun.

In the example the temperature T ₁ of the mist was painted under conditions such that the dew point T ₂ or more, whitening of the coating film was observed. In Examples 36 to 38, the coating composition did not become atomized due to the small amount of carbon dioxide in the coating composition. In Examples 39 to 41, no whitening of the coating film was observed, but mist formation was unstable.

DESCRIPTION OF SYMBOLS 1 ... Paint tank, 2, 6 ... High pressure pump, 3, 7 ... Heater, 4 ... Carbon dioxide cylinder, 5 ... Cooler, 8 ... Mixer, 9 ... Nozzle.

Claims (6)

Mixing carbon dioxide into the paint to obtain a coating composition;
Spraying the coating composition to form a mist;
Attaching the mist to an object to form a liquid film on the object;
The paint has a viscosity of 400 mPa · s or more at 20 ° C. and 1 atmosphere,
The amount of carbon dioxide is 1.5 parts by mass or more with respect to 100 parts by mass of the paint,
A coating method in which T ₁ and T ₂ satisfy T ₁ −T ₂ ≧ 0, where T ₁ is a temperature of the mist and T ₂ is a dew point of the environment around the mist. The method according to claim 1, wherein the paint and the carbon dioxide are mixed at a temperature and pressure at which the density of carbon dioxide is 0.7 kg / L or more. The method according to claim 1 or 2, wherein the paint contains 1% by mass or more of a solvent with respect to the total amount of the paint. The method according to any one of claims 1 to 3, wherein the paint and the carbon dioxide are mixed at a temperature and pressure at which carbon dioxide exists in a liquid state having a density of 0.7 kg / L or more. The method according to any one of claims 1 to 4, wherein the paint and the carbon dioxide are mixed at a temperature of less than 60 ° C. Measuring T ₁ and T ₂ ;
The method according to claim 1, further comprising adjusting a mixing ratio of the carbon dioxide and the paint so as to satisfy T ₁ -T ₂ ≧ 0.

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