JP7483259B2 - Coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating - Google Patents

Description

The present invention relates to a coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating.

Paints are required to not only have excellent performance after the paint film is applied, but also to have excellent workability. For example, even if the quality of the paint film after application is excellent, if the paint workability is poor, such as requiring a lot of labor to apply or being difficult to apply, the value of the paint will be greatly reduced.

One of the important aspects of painting workability is the minimum amount of paint splatter (also known as spatter). In spray painting, when the area to be painted and the area not to be painted are continuous on the surface of the workpiece, the non-painted area is masked with adhesive tape or similar to prevent paint from being applied to the non-painted area. Sheets are also installed to prevent paint from splattering in unintended directions and contaminating the surrounding area, but the time required for these steps can take up more than half of the total painting process. Furthermore, if there is a lot of paint splatter, the work efficiency of the painter decreases and the painting process can be delayed. In addition, paint that splatters on areas other than the target area is wasted, which increases the cost of paint.

For example, Patent Document 1 discloses a coating method in which paint is discharged from a nozzle head in the form of a liquid film or liquid column and applied to an object to be coated, with the aim of preventing atomized paint from scattering. However, while Patent Document 1 discloses that paint is applied to an object to be coated within a transition zone where the paint transitions from a liquid film or liquid column state to an atomized state, it does not disclose anything about the paint itself that can prevent paint from scattering.

Furthermore, Patent Document 1 points out the problem with spray painting, in that atomized paint particles are dispersed by air currents such as accompanying air currents. Thus, in spray painting, the paint that is sprayed is atomized and spreads out, so manual masking with appropriate force is required to ensure there are no gaps, and even if an automatic painting device is used, it is not very effective in shortening the painting process.

Therefore, preventing or reducing paint splashing can significantly shorten the process and reduce painting costs, thereby increasing the value of the paint.

JP 2015-107474 A

In addition, unlike painting with a roller or brush, when spray painting, there is a distance between the spray nozzle of the painting device and the object to be painted, so not only is it possible to prevent paint from scattering, but it is also important to be able to paint the desired area of the object with precision in order to increase the value of the paint.

Therefore, the present invention aims to provide a paint composition for ejection painting that suppresses or reduces paint scattering and has good painting accuracy.

The coating composition for liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating according to the present invention is
The first normal stress difference is 10 Pa or more;
The loss tangent (Tan δ) is 1.00 or less, and the paint thread necking inhibition (CON) value is 0.45 or less.
The coating composition is for liquid film jet coating, liquid column jet coating, or liquid droplet jet coating. By having the first normal stress difference, Tan δ, and CON value within the above ranges, it is possible to suppress or reduce paint scattering in liquid film jet coating, liquid column jet coating, and liquid droplet jet coating, and to exhibit good coating precision.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the first normal stress difference is 10 to 200 Pa.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the Tan δ is 0.5 to 1.0.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the CON value is 0.20 to 0.45.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the coating composition contains a resin component and a viscosity adjuster,
The viscosity modifier is at least one selected from the group consisting of alkali swelling type viscosity modifiers, urethane association type viscosity modifiers, and cellulose-based viscosity modifiers.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the viscosity is 0.1 to 2.0 Pa·s.

In one embodiment, the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention is for use on buildings.

The present invention provides a paint composition for extrusion coating that suppresses or reduces paint scattering and has good coating accuracy.

FIG. 1A is a schematic diagram showing how small droplets are formed during liquid column ejection coating using a conventional paint. FIG. 1B is a schematic diagram showing how small droplets are formed during coating using a conventional liquid column ejection coating method. FIG. 1C is a schematic diagram showing how small droplets are formed during liquid column ejection coating using a conventional paint. FIG. 1D is a schematic diagram showing how small droplets are formed during liquid column ejection coating using a conventional paint. FIG. 1E is a schematic diagram showing how small droplets are formed during liquid column ejection coating using a conventional paint.

The following describes embodiments of the present invention. These descriptions are intended to be illustrative of the present invention and are not intended to limit the present invention in any way.

In the present invention, two or more embodiments may be combined in any manner.

In the present invention, the paint and the paint composition can be used interchangeably.

In this specification, unless otherwise specified, numerical ranges are intended to include the upper and lower limits of the range. For example, 10-200 Pa means 10 Pa or more and 200 Pa or less.

In the present invention, the term "liquid film" refers to a coating composition in the form of a film or a surface. In the present invention, the term "liquid column" refers to a coating composition in the form of a column, line, or rod.

In the present invention, the term "liquid film ejection coating" refers to coating in which the coating composition is ejected in the form of a liquid film from an ejection port. In the present invention, the term "liquid column ejection coating" refers to coating in which the coating composition is ejected in the form of a liquid column from an ejection port. In the present invention, the term "droplet ejection coating" refers to coating in which a liquid film or liquid column of the coating composition is broken into droplets by turning the ejection on and off, and the droplets are applied while controlling the direction of each droplet.

Hereinafter, each of liquid film ejection coating, liquid column ejection coating, and liquid droplet ejection coating, or all three together, may be referred to simply as "ejection coating."

Hereinafter, the coating composition for ejection coating according to the present invention may be simply referred to as the "coating composition."

The drawings in this invention are drawn with a view to prioritizing understanding of the invention, and the dimensions, ratios, and distances of each component in the drawings are not accurate.

(Paint composition)
The coating composition for liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating according to the present invention is
The first normal stress difference is 10 Pa or more;
The loss tangent (Tan δ) is 1.00 or less, and the coating yarn necking inhibition (CON) value is 0.45 or less.
The coating composition is for liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating.

Figures 1A-E are schematic diagrams showing how small droplets are formed during conventional liquid column spray painting using paint. Just before spraying, the spray outlet 1 is filled with paint 2 (Figure 1A). As the paint column (liquid column) 3 is sprayed, a paint thread 4 is formed between the sprayed paint column 3 and the paint 2 remaining in the spray outlet (Figure 1B). As the paint column 3 is further sprayed, multiple thin parts (necks) 5 are formed in the paint thread 4 (Figure 1C). As the paint column 3 is further sprayed, the paint thread 4 breaks at the necks 5, and the paint column 3 separates (Figure 1D). The broken paint thread 4 then breaks again, becoming small droplets 6 that fly off (Figure 1E).

For this reason, the inventors speculated that the following (1) to (3) would be effective in suppressing paint scattering.
(1) Ensure that the paint thread in Figure 1B does not stretch.
(2) Suppressing the occurrence of necking in the paint thread of FIG. 1C.
(3) In FIG. 1D, the broken paint thread is made to immediately return in the direction of the paint that has been previously discharged or the paint remaining at the discharge port, in other words, the first normal stress difference of the paint is made high.

Regarding (1) above, the paint thread can be considered as a viscoelastic body having an elastic component and a viscous component, and it is believed that the paint thread will stretch if the viscous component is large relative to the elastic component. The loss tangent (Tan δ) is expressed as the loss modulus (viscous component) / storage modulus (elastic component). Therefore, in order to prevent the paint thread from stretching, the elastic component should be made large relative to the viscous component, i.e. Tan δ should be made low.

In the present invention, the loss tangent (Tan δ) is measured using dynamic viscoelasticity data measured using a stress-controlled rheometer "MCR302" manufactured by Anton Paar under the conditions of 50 mm parallel plates, gap: 0.5 mm, strain: linear strain, angular frequency: 100 s ^-1 , and measurement temperature: 23°C.

Regarding the above (2), the inventors observed the necking of the paint thread in Figure 1C and found that the necking did not occur in the center of the paint thread, but occurred randomly in the paint thread, causing the paint thread to break. From this, the inventors deduced that in the microstructure of the paint thread, some parts of the microstructure are broken and some parts are not broken, and in the broken parts, the viscosity decreases and necking occurs. Here, in a non-Newtonian fluid such as paint, as the shear rate increases within a certain shear rate range, the microstructure is usually broken and the viscosity decreases, such as the entanglement of molecular chains decreasing. Therefore, in order to suppress the occurrence of necking in the paint thread, the change in viscosity when the shear rate changes is reduced, that is, the shear rate dependency of the viscosity of the paint is reduced. In the present invention, the value of the shear rate dependency of the viscosity is taken as the CON value from the suppression of necking occurrence (Control of the Occurrence of a Neck).

In the present invention, the method for measuring the CON value is as follows. Using a stress-controlled rheometer "MCR302" manufactured by Anton Paar, steady flow measurements are performed at shear rates (dγ/dt) of 10 s ^-1 , 100 s ^-1 and 1000 s ^-1 under the conditions of 50 mm parallel plates, gap: 0.5 mm, and measurement temperature: 23° C., and the viscosities 30 seconds after the start of measurement are defined as η(10), η(100) and η(1000), respectively. Then, from the three sets of data, a graph is created with log ₁₀ (dγ/dt) on the horizontal axis and log ₁₀ (η) on the vertical axis, and a linear approximation equation is calculated from the three points by the least squares method, and the absolute value of the slope of the straight line is defined as the CON value.

Regarding the above (3), the normal stress is a stress that occurs in a direction perpendicular to the direction of shear when a rotational deformation is applied to a measurement object made of a viscoelastic fluid. The normal stress is not understood by itself, but by its difference with the shear stress. The first normal stress difference _N1 is defined as the first normal stress difference _N1 = _σxx - _σyy using the components of the stress tensor σ in a steady shear flow state with the flow velocity direction being x and the velocity gradient direction being y.

In the present invention, the first normal stress difference is determined from the measurement data 30 seconds after the start of measurement by performing steady flow measurement using a stress-controlled rheometer "MCR302" manufactured by Anton Paar under the conditions of 50 mm parallel plates, gap: 0.5 mm, shear rate: 100 s ^-1 , and measurement temperature: 23°C.

The inventors have found that paint scattering during jet coating can be suppressed or reduced by having the first normal stress difference calculated from these be 10 Pa or more, Tan δ be 1.00 or less, and the CON value be 0.45 or less. Even more surprisingly, the inventors have found that good coating accuracy can be obtained during jet coating by setting the first normal stress difference, Tan δ, and CON value within the above-mentioned specified ranges.

When the first normal stress difference is less than 10 Pa, the force that causes the paint threads generated during discharging to return in the direction of the previously discharged paint or the direction of the paint remaining at the discharge port is weak, so paint scattering during discharge coating cannot be sufficiently suppressed or reduced.

In one embodiment, the first normal stress difference is 10 Pa or more, 20 Pa or more, 30 Pa or more, 40 Pa or more, 50 Pa or more, 60 Pa or more, 70 Pa or more, 80 Pa or more, 90 Pa or more, 100 Pa or more, 110 Pa or more, 120 Pa or more, 130 Pa or more, 140 Pa or more, 150 Pa or more, 160 Pa or more, 170 Pa or more, 180 Pa or more, 190 Pa or more, or 200 Pa or more. In one embodiment, the first normal stress difference is 1000 Pa or less, 900 Pa or less, 800 Pa or less, 700 Pa or less, 600 Pa or less, 500 Pa or less, 400 Pa or less, 300 Pa or less, 200 Pa or less, 190 Pa or less, 180 Pa or less, 170 Pa or less, 160 Pa or less, 150 Pa or less, 140 Pa or less, 130 Pa or less, 120 Pa or less, 110 Pa or less, 100 Pa or less, 90 Pa or less, 80 Pa or less, 70 Pa or less, 60 Pa or less, 50 Pa or less, 40 Pa or less, 30 Pa or less, or 20 Pa or less. In another embodiment, the first normal stress difference is 10 to 200 Pa. In yet another embodiment, the first normal stress difference is 10 to 190 Pa.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the first normal stress difference is 10 to 200 Pa.

If Tan δ is greater than 1.00, the paint threads will stretch too much, and paint scattering cannot be sufficiently suppressed or reduced.

In one embodiment, Tan δ is 1.00 or less, 0.95 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, 0.20 or less, 0.15 or less, or 0.10 or less. In one embodiment, Tan δ is 0.05 or more, 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, 0.50 or more, 0.55 or more, 0.60 or more, 0.65 or more, 0.70 or more, 0.75 or more, 0.80 or more, 0.85 or more, 0.90 or more, or 0.95 or more. In another embodiment, Tan δ is 0.50 to 1.00. In yet another embodiment, Tan δ is 0.70 to 1.00.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the Tan δ is 0.5 to 1.0.

If the CON value is greater than 0.45, the paint thread is likely to become constricted, leading to breakage of the paint thread, and paint scattering cannot be sufficiently suppressed or reduced.

In one embodiment, the CON value is 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, 0.20 or less, 0.15 or less, or 0.10 or less. In one embodiment, the CON value is 0.05 or more, 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, or 0.40 or more. In another embodiment, the CON value is 0.30 to 0.45. In yet another embodiment, the CON value is 0.30 to 0.40.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the CON value is 0.20 to 0.45.

The viscosity of the paint composition is not particularly limited and may be adjusted as appropriate. As shown in the examples described below, there is no correlation between viscosity and the amount of paint splashing. Therefore, viscosity is not a key factor for controlling the amount of paint splashing, but from the viewpoint of maintaining or enhancing the application feel of the paint, the viscosity of the paint composition is preferably, for example, 0.1 to 2.0 Pa·s, and more preferably 0.1 to 1.5 Pa·s.

On the other hand, a topcoat coating is required to have a more homogeneous coating film to improve the appearance of the coating film than an undercoat coating film, so a coating film with a thin thickness is often formed. A paint with a relatively high viscosity is likely to be applied to the target surface in a large amount, which is suitable for forming a coating film with a thick thickness, but it is difficult to form a homogeneous coating film with a thin thickness. In contrast, a paint with a relatively low viscosity is likely to be applied to the target surface in a small amount, which is suitable for forming a homogeneous coating film with a thin thickness. For this reason, from the viewpoint of forming a coating film with a thin thickness, the viscosity of the coating composition is preferably, for example, 0.1 to 2.0 Pa·s, and more preferably 0.1 to 1.5 Pa·s.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the viscosity is 0.1 to 2.0 Pa·s. This makes it easy to form a coating film with a thin thickness, and is suitable for forming a topcoat coating for interior and exterior use.

In the present invention, the viscosity (Pa·s) of the coating composition is measured by steady flow measurement using an Anton Paar stress-controlled rheometer "MCR302" with 50 mm parallel plates, a gap of 0.5 mm, a shear rate of 1000 s ^-1 , and a measurement temperature of 23°C, and the viscosity is measured 30 seconds after the start of measurement.

The coating composition typically contains a resin component, a crosslinker, a pigment, and water and/or a solvent. The coating composition may contain other components.

Resin component The resin component functions as a coating film forming element. As the resin component, a resin component of a conventionally known coating composition can be used. As the resin component, for example, acrylic resin, polyester resin, alkyd resin, fluororesin, epoxy resin, polyurethane resin, polyether resin, etc. can be mentioned. In addition, as the resin component, for example, a polymer compound containing an inorganic component or consisting of an inorganic component, such as a silicone resin or an alkoxysilane condensate, can also be used. The resin component may be used alone or in combination of two or more kinds.

The resin component may be in an organic solvent form, an aqueous form (water-soluble, water-dispersible or emulsion), or a non-aqueous dispersion form.

The coating composition using the above resin component may be, for example, a one-component type, a two-component mixed type consisting of a base agent and a curing agent, or a multi-component mixed type of three or more components.

The resin component can undergo a curing reaction by heating or at room temperature.

The amount of the resin component is not particularly limited and may be adjusted as appropriate. In one embodiment, the solid content of the resin component is 10 to 90 parts by mass or 10 to 60 parts by mass per 100 parts by mass of the total of the solid content of the resin component and the solid content of the pigment.

Crosslinking agent The coating composition may contain a crosslinking agent. The crosslinking agent may be selected according to the curable functional group of the resin component. For example, the crosslinking agent may be a carbodiimide compound, a hydrazine compound, an amino resin, a (blocked) polyisocyanate compound, an amine compound, a polyamide compound, or a polycarboxylic acid compound. The crosslinking agent may be used alone or in combination of two or more.

Pigments The pigment is not particularly limited, and known paint pigments can be used. Examples of pigments include color pigments such as titanium dioxide, carbon black, red iron oxide, and phthalocyanine blue; extender pigments such as calcium carbonate, talc, and mica; and rust-preventive pigments. The pigments may be used alone or in combination of two or more.

Viscosity Adjuster In the present invention, a known viscosity adjuster may be used to adjust the first normal stress difference, Tan δ, and CON value of the coating composition. Examples of the viscosity adjuster include alkali swelling type viscosity adjuster, urethane association type viscosity adjuster, cellulose-based viscosity adjuster, amide-based viscosity adjuster, inorganic layered compound-based viscosity adjuster, and aminoplast-based viscosity adjuster.

Examples of alkali swelling viscosity modifiers include polycarboxylic acid viscosity modifiers, polysulfonic acid viscosity modifiers, and polyphosphoric acid viscosity modifiers.

Commercially available alkali swelling viscosity modifiers include, for example, the SN Thickener series, such as SN Thickener 615, 630, 636, and 640 manufactured by San Nopco; and the Primal (registered trademark) series, such as Primal (registered trademark) ASE-60 manufactured by The Dow Chemical Company.

Examples of urethane association type viscosity modifiers include urethane modified polyether type viscosity modifiers.

Commercially available urethane association viscosity modifiers include, for example, the ADEKA NOL (registered trademark) UH series, such as ADEKA NOL (registered trademark) UH-140S, 420, 450, 526, 540, and 550 manufactured by ADEKA Corporation; and SN Thickener 665T manufactured by SAN NOPCO.

Examples of cellulose-based viscosity modifiers include crystalline cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

Examples of commercially available cellulose-based viscosity modifiers include the Ceolus (registered trademark) series, such as the Ceolus (registered trademark) RC series manufactured by Asahi Kasei Corporation; and the Cellosize (registered trademark) series, such as Cellosize QP 4400 and 52000H manufactured by The Dow Chemical Company.

Examples of amide-based viscosity adjusters include fatty acid amides, polyamides, acrylamides, long-chain polyaminoamides, aminoamides, and salts thereof (e.g., phosphates).

Examples of inorganic layered compound viscosity adjusters include layered compounds such as montmorillonite, bentonite, and clay.

Examples of aminoplast viscosity modifiers include hydrophobically modified ethoxylate aminoplast associative viscosity modifiers.

The following are some guidelines for adjusting the first normal stress difference, Tan δ, and CON value of a coating composition:

To increase the first normal stress difference, a viscosity modifier with a large molecular weight may be used. Examples of such viscosity modifiers include the SN Thickener series, such as SN Thickener 615, 630, 636, and 640, which are alkali swelling type viscosity modifiers; and the Primal (registered trademark) series, such as Primal (registered trademark) ASE-60 manufactured by The Dow Chemical Company.

To lower Tan δ, a viscosity modifier with a hard structure may be used. Examples of such viscosity modifiers include the Ceolus (registered trademark) series, such as the Ceolus (registered trademark) RC series, which is a cellulose-based viscosity modifier manufactured by Asahi Kasei Corporation; and the Cellosize (registered trademark) series, such as Cellosize QP 4400 and 52000H, manufactured by The Dow Chemical Company.

To reduce the CON value, a viscosity modifier with low interaction can be used. Examples of such viscosity modifiers include the ADEKA Corporation ADEKANOL (registered trademark) UH series, which is a urethane association type viscosity modifier, such as ADEKANOL (registered trademark) UH-140S, 420, 450, 526, 540, and 550.

The viscosity adjusters may be used alone or in combination of two or more.

In one embodiment of the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention, the coating composition contains a resin component and a viscosity adjuster,
The viscosity modifier is at least one selected from the group consisting of alkali swelling type viscosity modifiers, urethane association type viscosity modifiers, and cellulose-based viscosity modifiers.

The content of the viscosity modifier in the coating composition of the present invention is not particularly limited and may be adjusted as appropriate.

The solid content of the viscosity modifier in the coating composition of the present invention is, for example, 0.1 to 3.0 parts by mass or 0.5 to 2.0 parts by mass per 100 parts by mass of the coating composition. In the present invention, "100 parts by mass of the coating composition" means 100 parts by mass of the entire coating composition including the solid content of the resin component, pigment component, viscosity modifier, etc., as well as the dispersion medium thereof; water and/or solvent.

The coating composition of the present invention may be either an aqueous coating composition or a solvent-based coating composition. In one embodiment, the coating composition of the present invention is an aqueous coating composition. In another embodiment, the coating composition is a coating composition that satisfies the requirements of JIS A 6909.

In the present invention, a coating composition in which the dispersion medium contained in the greatest amount is water is called an aqueous coating composition. In the present invention, a coating composition in which the dispersion medium contained in the greatest amount is a solvent is called a solvent-based coating composition.

The total amount of paint solids in the paint composition of the present invention may be adjusted as appropriate and is not particularly limited. For example, the total amount of paint solids is 20 to 80 parts by mass, preferably 50 to 80 parts by mass, per 100 parts by mass of the paint composition.

Solvent When a solvent is used, a solvent for a conventionally known coating composition can be appropriately selected and used. For example, alcohols such as methanol, ethanol, 2-propanol, and 1-butanol; esters such as ethyl acetate, butyl acetate, isobutyl acetate, ethyl propionate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as diethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, and tetrahydrofuran (THF); ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1, Examples of the solvent include glycols such as 3-butylene glycol, pentamethylene glycol, and 1,3-octylene glycol; amides such as formamide, N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO), and N-methylpyrrolidone (NMP); ketones such as acetone, methyl ethyl ketone (MEK), methyl propyl ketone, methyl isobutyl ketone, acetylacetone, and cyclohexanone; aliphatic hydrocarbons such as mineral spirits and kerosene; aromatic hydrocarbons such as toluene, xylene, mesitylene, and dodecylbenzene; and halogenated solvents such as chloroform and dichloromethylene. The solvents may be used alone or in combination of two or more.

The coating composition of the present invention may be of the room temperature drying type or the heat drying type. In one embodiment, the coating composition of the present invention is of the room temperature drying type.

The coating composition of the present invention may be a one-component type or a two-component type.

When the coating composition is an aqueous coating composition, the content of the solvent may be adjusted as appropriate. For example, it is 0 to 15 parts by mass, preferably 0 to 10 parts by mass, per 100 parts by mass of the coating composition. In this case, for example, alcohols can be used as the solvent.

Other Components In addition to the above-mentioned components, the coating composition of the present invention may contain other components such as dispersants, film-forming assistants, antifreezing agents, crosslinking accelerators, curing agents, leveling agents, surface conditioners, defoamers, plasticizers, preservatives, antifungal agents, UV stabilizers, etc. Each of these other components may be used alone or in combination of two or more.

Uses of the coating composition The coating composition according to the present invention is a coating composition for at least one of liquid film discharge coating, liquid column discharge coating, and droplet discharge coating, i.e., liquid film discharge coating, liquid column discharge coating, and droplet discharge coating. In one embodiment, liquid film discharge coating does not include curtain flow coating. As described above, droplet discharge coating is a coating in which a coating composition of a liquid film or liquid column is broken into droplets by on and off of discharge, and the droplets are applied in a state in which the direction of each droplet is controlled. In contrast, spray coating and electrostatic coating are coating in which the coating composition is not on and off of discharge, but is broken by shear with air or centrifugal force, and the droplets are applied in a state in which the direction of each droplet is not controlled. Therefore, spray coating and electrostatic coating are not included in the "droplet discharge coating" of the present invention. In another embodiment, the coating composition according to the present invention is a coating composition for liquid film discharge coating or liquid column discharge coating.

As described above, the coating composition of the present invention suppresses or reduces paint scattering and has good coating accuracy, so it can be suitably used for coating with an automatic coating device such as a robot without masking, particularly for coating large objects such as buildings, objects to be coated outdoors, and objects to which electrostatic coating cannot be applied. With an automatic coating device such as a robot, the object to be coated and the coating pattern can be programmed in advance, and a coating material with good coating accuracy and no paint scattering can be used, so that coating can be easily performed with high accuracy even without masking, and a high-quality coating film can be formed, which has a great effect of shortening the coating process and reducing coating costs.

In one embodiment, the coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to the present invention is for use on buildings.

In one embodiment, the coating composition of the present invention is for interior use. In another embodiment, the coating composition of the present invention is for exterior use.

- Method for preparing coating composition The method for preparing the coating composition is not particularly limited as long as the first normal stress difference, Tan δ and CON value are within the predetermined range, and the coating composition can be prepared by mixing the above-mentioned resin component, pigment, viscosity modifier, etc. by a conventionally known method. In addition, the coating composition of the present invention may be prepared by adding a viscosity modifier or the like to a commercially available coating material containing a resin component and a pigment to adjust the first normal stress difference, Tan δ and CON value to within the predetermined range.

- Method for preparing a coating film The method for preparing a coating film is not particularly limited, except that the coating composition of the present invention is applied using a discharge coating method. For example, a coating film can be prepared by applying the coating composition of the present invention by liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating using a discharge coating device, jet dispenser, or the like described in Patent Document 1. The drying temperature after applying the coating composition may be appropriately adjusted depending on the solvent, etc. For example, when drying is required in a short time such as 10 seconds to 30 minutes, the temperature may be 60 to 200°C, and 80 to 160°C is preferable. When drying is not required in a short time, drying may be performed, for example, at room temperature.

Examples of coating devices capable of ejection coating include the ejection coating device of Patent Document 1; EcoPaintJet (registered trademark) manufactured by Durr; and jet dispensers. Jet dispensers include piezo jet dispensers that control ejection using a piezo element, and electromagnetic jet dispensers that control ejection using an electromagnetic valve. Examples of piezo jet dispensers include the Stream Jet E series manufactured by SSI JAPAN. Examples of electromagnetic jet dispensers include NOVADOT and JETTY manufactured by Sanei Tech Co., Ltd.

In the case of ejection coating in which the coating composition of the present invention is applied, the number of ejection ports of the coating device is not particularly limited, and may be, for example, one or two or more. The shape of the ejection port of the coating device is not particularly limited. For example, the cross-sectional shape of the ejection port may be a circle, an ellipse, a polygon (triangle, square, pentagon, hexagon, heptagon, octagon, etc.), a convex shape, a concave shape, or a combination of these.

The dimensions of the liquid film and liquid column when the coating composition is discharged as a liquid film or liquid column are not particularly limited, and may be adjusted appropriately depending on the movement speed of the discharge port, the distance between the discharge port and the substrate, the thickness of the coating film to be formed, etc.

The object on which a coating film is formed using the coating composition of the present invention is not particularly limited and can be selected appropriately. For example, the object includes the interior and exterior of the body of a vehicle such as an automobile or a railroad car, the body of an aircraft, the hull and superstructure (rigging) of a ship; the interior, exterior and roof of a building; furniture, fittings; window glass of a vehicle, an aircraft, a ship, a building, etc.; cases, containers, resin plates, films; housings and glass parts of electrical appliances such as displays, monitors, and refrigerators; coatings applied thereto; inorganic building materials such as various cements, ceramic building materials, lightweight foamed concrete, mortar, slate boards, roofs, tiles, and ALC; wood; various types of glass; metal substrates such as steel plates, aluminum, and stainless steel; and the like. As described above, in a preferred embodiment, the object on which a coating film is formed using the coating composition of the present invention is a building.

Thus, examples of articles having a coating film formed using the coating composition of the present invention include vehicles such as automobiles and railroad cars, aircraft, ships, buildings, furniture, fixtures, window glass, transparent bodies (including cases, containers, resin plates and films), electrical appliances, etc. In a preferred embodiment, the article having a coating film formed using the coating composition of the present invention is a building.

The present invention will be described in more detail below with reference to examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

The first normal stress difference, Tan δ, CON value and viscosity of the coating composition were determined using the methods described above.

As the ejection coating device, a piezo-jet coating device (Stream Jet E series) manufactured by SSI JAPAN was used.
The object to be painted was Maruman colored drawing paper Mitant 361-667P.

Details of each component of the coating composition used in the examples are as follows.
Resin component: Acrylic emulsion prepared in the Preparation Example described below White pigment: Titanium dioxide (solid content: 100%)
Extender pigment: calcium carbonate (solid content: 100%)
Additives: Dispersant (manufactured by BYK Japan under the trade name "DISPERBYK-190"), Defoamer (manufactured by Kyoeisha Chemical under the trade name "Aqualene 8020"), Surface Conditioner (manufactured by Kyoeisha Chemical under the trade name "Polyflow KL-100")
Viscosity modifier 1 (cellulose-based viscosity modifier): Trade name "CEOLUS (registered trademark) RC-591" manufactured by Asahi Kasei Corporation (solid content: 100%, indicated as RC-591 in Table 1)
Viscosity modifier 2 (cellulose-based viscosity modifier): Trade name "Cellosize QP 52000H" manufactured by The Dow Chemical Company (solid content: 100%, indicated as QP 52000H in Table 1)
Viscosity modifier 3 (urethane association type viscosity modifier): Trade name "ADEKA NOL (registered trademark) UH-540" manufactured by ADEKA Corporation (solid content: 30%, indicated as UH-540 in Table 1)
Viscosity modifier 4 (urethane association type viscosity modifier): Trade name "ADEKA NOL (registered trademark) UH-140S" manufactured by ADEKA Corporation (solid content: 30%, indicated as UH-140S in Table 1)
Viscosity modifier 5 (urethane association type viscosity modifier): Trade name "ADEKA NOL (registered trademark) UH-420" manufactured by ADEKA Corporation (solid content: 30%, indicated as UH-420 in Table 1)
Viscosity modifier 6 (urethane association type viscosity modifier): Trade name "ADEKA NOL (registered trademark) UH-450" manufactured by ADEKA Corporation (solid content: 30%, indicated as UH-450 in Table 1)
Viscosity modifier 7 (polycarboxylic acid-based viscosity modifier): Trade name "SN Thickener 640" manufactured by San Nopco (solid content: 30%, indicated as SN 640 in Table 1)
Viscosity modifier 8 (alkali swelling type viscosity modifier): Trade name "Primal (registered trademark) ASE-60" manufactured by Dow Chemical Company (solid content: 28%, indicated as ASE-60 in Table 1)
Viscosity modifier 9 (alkali swelling type viscosity modifier): Trade name "SN Thickener 630" manufactured by San Nopco (solid content: 30%, indicated as SN 630 in Table 1)

(Acrylic emulsion preparation example)
In accordance with the preparation of an acrylic emulsion described in paragraph [0078] of WO 2018/079212, an emulsion resin having a solid content of 49% by mass and a volume average particle diameter of 0.12 μm was obtained as a product.

(Examples 1 to 14 and Comparative Examples 1 to 7)
A coating composition was prepared by mixing the components in the proportions (parts by mass) shown in Table 1. The first normal stress difference, Tan δ, CON value, and viscosity of the coating composition were measured. The results are shown in Table 1.

(Evaluation of paint scattering and painting accuracy)
Each prepared coating composition was filled into a cartridge of a discharge coating device. The discharge nozzle of the coating device was arranged perpendicular to the paper surface to be coated. The distance between the discharge nozzle and the paper surface was set to 10 mm. Then, while moving the discharge nozzle in one direction parallel to the paper surface, liquid columns were discharged to coat the coating material so that the coating material was arranged at intervals of 0.6 mm, and 10 straight lines of 100 mm in length were coated. The straight lines immediately after coating were visually observed, and the scattering of the coating material and the coating accuracy were evaluated according to the following criteria. Scores 1 and 2 were acceptable, and scores 3 and 4 were unacceptable.
Paint scattering evaluation criteria: Rating 1: Almost no paint scattered in areas other than the painted straight line.
Rating 2: A small amount of paint was seen to have splashed onto areas other than the painted straight line.
Rating 3: Spattered paint was observed in areas other than the painted straight line.
Rating 4: Paint splatter was evident in areas other than the painted straight line.
Paint application accuracy evaluation criteria Rating 1: Almost no jagged edges on the contours of painted straight lines.
Rating 2: Some jagged edges were observed on the contours of painted straight lines.
Rating 3: Jagged edges were observed along the contours of painted straight lines.
Rating 4: Jagged edges were clearly observed on the contours of painted straight lines.

＊１：カッコ内の値は、固形分量を表す。＊２：カッコ内の値は、塗料組成物１００質量部に対する、各粘性調整剤の固形分量または粘性調整剤の合計固形分量を表す。

*1: The value in parentheses indicates the solid content. *2: The value in parentheses indicates the solid content of each viscosity modifier or the total solid content of the viscosity modifiers per 100 parts by mass of the coating composition.

As shown in Table 1, the present invention has been able to provide a paint composition for ejection coating that suppresses or reduces paint scattering and has good coating accuracy. Furthermore, a comparison between Examples 9 and 13 shows that paint scattering differs when the physical properties are different, even for paint compositions with similar viscosities. This shows that paint scattering cannot be suppressed simply by viscosity alone.

The present invention provides a paint composition for extrusion coating that suppresses or reduces paint scattering and has good coating accuracy.

1: Outlet 2: Paint 3: Paint column 4: Paint thread 5: Constriction 6: Small droplet

Claims (7)

The first normal stress difference is 10 Pa or more;
The loss tangent (Tan δ) is 1.00 or less, and the paint thread necking inhibition (CON) value is 0.45 or less.
A coating composition for liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating. The coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to claim 1, wherein the first normal stress difference is 10 to 200 Pa. The coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to claim 1 or 2, wherein the Tan δ is 0.5 to 1.0. The coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to any one of claims 1 to 3, wherein the CON value is 0.20 to 0.45. Contains a resin component and a viscosity modifier,
The coating composition for liquid film discharge coating, liquid column discharge coating, or liquid droplet discharge coating according to any one of claims 1 to 4, wherein the viscosity modifier is one or more selected from the group consisting of an alkali swelling type viscosity modifier, a urethane association type viscosity modifier, and a cellulose-based viscosity modifier. A coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to any one of claims 1 to 5, having a viscosity of 0.1 to 2.0 Pa·s. A coating composition for liquid film ejection coating, liquid column ejection coating, or liquid droplet ejection coating according to any one of claims 1 to 6, which is for use on buildings.

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