JP7446412B2 - Coating film manufacturing method - Google Patents

Description

The present disclosure relates to a method for manufacturing a coating film.

A method is known for producing a desired coating film on a support using a continuous roll-to-roll process.
As a method for producing a coating film, for example, there is a method in which a coating solution for obtaining a desired coating film is applied onto a support, and the resulting coating solution film is dried. In this method, curl regulating means may be used to suppress curling (also referred to as warpage) of the coating film.

As an example of a method in which a curl control means is applied in the drying process, Patent Document 1 describes a development processing section that develops an undeveloped photographic film, and a development processing section that performs a drying processing of the developed photographic film. In the film developing apparatus, the drying processing section includes a hot air blowing means for drying the developed photographic film by blowing hot air thereon, and a drying processing section for transporting the photographic film while drying the photographic film. and a curl regulating means for regulating curl in the width direction of the film due to the drying process of the photographic film. A method using a film developing device provided is disclosed.

Furthermore, Patent Documents 2 to 5 disclose various curl regulating means.

Japanese Patent Application Publication No. 2006-154375 Japanese Patent Application Publication No. 2014-166900 Japanese Patent Application Publication No. 2014-005085 JP2012-125973A Japanese Patent Application Publication No. 10-337848

For example, it is a method of producing a coating film on a support that is continuously conveyed, such as a continuous roll-to-roll process, in which a water-based coating liquid is applied onto the support to form a coating liquid film. In a method for manufacturing a coating film that includes a step of forming a coating liquid film and a step of drying the formed coating liquid film, cracks and curls may occur in the obtained coating film.

Therefore, the problem to be solved by an embodiment of the present disclosure has been made in view of the above circumstances, and is a method of manufacturing a coating film on a continuously conveyed support (for example, by a roll-to-roll method). It is an object of the present invention to provide a method for manufacturing a coating film that can produce a coating film in which cracks and curls are suppressed in a method using a continuous process.

Means for solving the above problems include the following embodiments.
<1> Step A of continuously conveying a long support and applying an aqueous coating liquid onto the continuously conveyed support;
Step B of drying the coating liquid film obtained in Step A on a continuously conveyed support;
including;
In the constant rate drying stage of the coating liquid film in step B, while the solid content concentration of the coating liquid film is between 70% by mass and 95% by mass, the coating is applied to the laminate consisting of the support and the coating liquid film. A coating film manufacturing method that starts curl control without contacting the coating liquid film.

<2> The method for producing a coating film according to <1>, wherein the solid content concentration of the coating liquid in step A is 30% by mass to 60% by mass.
<3> The method for producing a coating film according to <1> or <2>, wherein the aqueous coating liquid is a coating liquid containing particles.
<4> Non-contact curl control is performed by blowing gas on one or both sides of the laminate and continuously conveying the laminate while bending it in the thickness direction by the wind pressure of the gas, <1> to <3> The method for producing a coating film according to any one of the above.
<5> The method for producing a coating film according to any one of <1> to <4>, wherein the support is a metal support.
<6> The method for producing a coating film according to any one of <1> to <5>, wherein the support has a thickness of 10 μm to 30 μm.

According to an embodiment of the present disclosure, there is provided a method for producing a coated film on a support that is continuously conveyed, in which a coated film with suppressed cracks and curls can be obtained. .

FIG. 1 is a schematic diagram showing each step of a method for manufacturing a coating film according to an embodiment. FIG. 2 is a schematic side view for explaining an example of the curl regulating means in step B. FIG. 3 is a schematic side view for explaining another example of the curl regulating means in step B. FIG. 4 is a schematic diagram illustrating a method for measuring the amount of curl.

Hereinafter, embodiments of a method for manufacturing a coating film will be described. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

In the present disclosure, a numerical range indicated using "~" means a range that includes the numerical values listed before and after "~" as the minimum and maximum values, respectively.
In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.
The elements in the drawings of the present disclosure are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure.
Furthermore, in each drawing, components having the same functions are designated by the same reference numerals, and redundant explanations will be omitted.
In the present disclosure, the "width direction" refers to a direction perpendicular to the longitudinal direction of the elongated support, the coating liquid film, and the coating film.
In the present disclosure, a combination of two or more preferred forms or aspects is a more preferred form or aspect.

≪Coating film manufacturing method≫
As mentioned above, this is a method for producing a coating film on a continuously conveyed support, which includes the steps of applying an aqueous coating solution onto the support to form a coating solution film, and In a method for producing a coating film that includes a step of drying a coating liquid film, cracks and curls may occur in the obtained coating film.
The occurrence of cracks and curls in the coating film is a phenomenon that appears significantly when an aqueous coating solution in which the solvent or dispersion medium is substantially water is used as the coating solution.
The present inventors investigated the method for producing the above-mentioned coating film and found that by starting non-contact curl control on the coating liquid film at a certain timing in the constant rate drying stage, cracks and curls could be prevented. It was discovered that it is possible to produce a coating film with suppressed properties, and the present invention was completed.

The method for producing a coating film according to the present embodiment includes a step A in which a long support is continuously transported and a water-based coating liquid is applied onto the continuously transported support; and a step B of drying the coating liquid film obtained in step A, and in the constant rate drying stage of the coating liquid film in step B, the solid content concentration of the coating liquid film is 70% by mass or more. This is a method for producing a coating film, in which curl control is started on a laminate consisting of a support and a coating liquid film without contacting the coating liquid film while the coating liquid film is at 95% by mass.

According to the method for manufacturing a coating film according to the present embodiment, a coating film in which cracks and curls are suppressed can be obtained.

On the other hand, none of Patent Documents 1 to 5 describes curl control in the drying process of the coating liquid film. That is, none of Patent Documents 1 to 5 describes the relationship between the solid content concentration of the coating liquid film and the timing of starting curl control.

Hereinafter, each step of the method for manufacturing a coating film of this embodiment will be explained.

First, an example of a method for manufacturing a coating film will be described with reference to FIG. 1.
As shown in FIG. 1, when the tip of the wound long support 10 is fed out and continuous conveyance is started, a water-based coating liquid is applied by the coating means 20 (Step A). In step A, a coating liquid film of an aqueous coating liquid is formed on the elongated support.
Subsequently, the laminate 12 of the coating liquid film formed in step A and the support 10 is continuously conveyed through the drying means 30 to dry the coating liquid film on the support 10. (Step B). In step B, the coating liquid film on the long support is dried to form a coating film.

[Process A]
In step A, a long support is continuously conveyed, and an aqueous coating liquid is applied onto the continuously conveyed support.
Here, the aqueous coating liquid refers to a coating liquid in which the solvent (or dispersion medium) contained in the coating liquid is substantially water. "The solvent (or dispersion medium) is substantially water" means that it is permissible to contain a solvent other than water introduced when using a solid content, and in the total solvent (or total dispersion medium) The proportion of water in the total solvent (or total dispersion medium) is preferably 95% by mass or higher, and the total solvent (or total dispersion medium) is water. It is particularly preferable.
Moreover, the solid content refers to components excluding the solvent (or dispersion medium).

-Support-
The elongated support used in this step is not particularly limited as long as it is applicable to roll-to-roll.
On the other hand, supports with high thermal conductivity, such as metal supports, are more likely to cause cracks and curls in the coated film. In the method for producing a coated film according to the present embodiment, a coated film with suppressed cracks and curls can be obtained even when a support with high thermal conductivity is used.

Examples of the support having high thermal conductivity include a support having a thermal conductivity of 200 W/(m·K) or more. In addition, if the support used in this step is, for example, a support with a multilayer structure including metal foil and a resin film, if the thermal conductivity of the support as a whole is 200 W/(m・K) or more, the heat The support has a conductivity of 200 W/(m·K) or more.
The upper limit of the thermal conductivity of the support is not particularly limited, and is, for example, 500 W/(m·K).

Examples of the support exhibiting the above-mentioned thermal conductivity include metal supports. More specifically, examples of the support exhibiting the above thermal conductivity include metal supports made of copper, aluminum, silver, gold, and alloys thereof.
In addition, the metal support may be made of stainless steel, nickel, titanium, or invar alloy.
Among these, a copper support and an aluminum support are preferably used from the viewpoint of shape stability as a support, usage history, etc.

The thermal conductivity of the support is measured using the laser flash method.
Specifically, for example, it is measured by the following method.
First, the support is cut out at three locations along the width direction (specifically, at a position 5 mm from both edges in the width direction and at the center in the width direction) with a diameter of 5 mm to 10 mm to obtain three measurement samples. Thermal conductivity of the three measurement samples obtained is measured using a thermophysical property measuring device (Kyoto Electronics Industry Co., Ltd., Model LFA-502) applying the laser flash method. The arithmetic mean value of the three measured values is taken as the thermal conductivity of the support.

The thickness of the support may be appropriately set from the viewpoint of application to a roll-to-roll system.
The thickness of the support is, for example, preferably 3 μm to 50 μm, more preferably 10 μm to 30 μm.
The width and length of the support may be appropriately set from the viewpoint of application to the roll-to-roll method and the intended width and length of the coating film.

The thickness of the support is measured as follows.
That is, the thickness of the support was measured at three locations along the width direction (specifically, at a position 5 mm from both edges in the width direction and at the center in the width direction) using a contact-type thickness measuring device, such as one manufactured by Co., Ltd. Measured using Fuji Works S-2270. The arithmetic mean value of the three measured values is taken as the thickness of the support.

-Water-based coating fluid-
As described above, the aqueous coating liquid used in this step is not particularly limited as long as it is a liquid containing water as a solvent (or dispersion medium) and a solid content.
The solid content contained in the aqueous coating liquid includes components for improving coating suitability in addition to components for obtaining the desired coating film.

Examples of the water contained in the aqueous coating solution include natural water, purified water, distilled water, ion exchange water, pure water, and ultrapure water (eg, Milli-Q water). Note that Milli-Q water is ultrapure water obtained by Merck Millipore's Milli-Q water production device.

The content of water in the aqueous coating liquid is not particularly limited, and for example, it is preferably 40% by mass or more, more preferably 50% by mass or more, based on the total mass of the aqueous coating liquid.
The upper limit of the water content may be less than 100% by mass, but for example, from the viewpoint of coating suitability, it is 80% by mass based on the total mass of the water-based coating liquid.

The aqueous coating liquid may contain particles as one of the solid components. That is, the aqueous coating liquid may be a coating liquid containing particles.
When an aqueous coating liquid containing particles is used, cracks and curls tend to occur because particles agglomerate in the constant rate drying stage. However, by applying the method for producing a coating film according to the present embodiment, cracks and curls occurring in the coating film can be suppressed even when an aqueous coating liquid containing particles is used.

The particles are not particularly limited as long as they are granular, and may be inorganic particles, organic particles, or composite particles of an inorganic substance and an organic substance.

As the inorganic particles, known inorganic particles applicable to the intended coating film can be used.
Examples of inorganic particles include particles of metals (alkali metals, alkaline earth metals, transition metals, etc., and alloys of these metals), particles of semimetals (silicon, etc.), or compounds of metals or semimetals (oxides, etc.). , hydroxide, nitride, etc.), pigment particles containing carbon black, etc.
Other examples of the inorganic particles include mineral particles such as mica, inorganic pigment particles, and polycrystalline diamond.

As the organic particles, known organic particles applicable to the intended coating film can be used.
The organic particles are not particularly limited as long as they are solid organic particles, including resin particles and organic pigment particles.

Composite particles of inorganic and organic substances include composite particles in which inorganic particles are dispersed in a matrix of organic substances, composite particles in which organic particles are coated with an inorganic substance, and inorganic particles in which the periphery is coated with an organic substance. Examples include composite particles.

The particles may be surface-treated for the purpose of imparting dispersibility or the like.
Note that the above-mentioned composite particles may be formed by surface treatment.

There are no particular restrictions on the particle size, specific gravity, usage form (for example, whether or not to use in combination), etc. of the particles, and they may vary depending on the intended coating film or conditions suitable for producing the coating film. , may be selected as appropriate.

The content of particles in the water-based coating liquid is not particularly limited, and may be adjusted as appropriate depending on the desired coating film, conditions suitable for manufacturing the coating film, or the purpose of adding the particles. , as long as it is determined.

The solid content contained in the aqueous coating liquid is not particularly limited, and includes various components used to obtain the desired coating film.
Specifically, the solid content contained in the aqueous coating liquid includes, in addition to the above-mentioned particles, a binder component, a component that contributes to the dispersibility of particles, a polymerizable compound, a reactive component such as a polymerization initiator, a surfactant, etc. Components and other additives for improving the coating performance of the coating material are included.

The solid content concentration of the aqueous coating liquid used in this step is not particularly limited, but is preferably less than 70% by mass, more preferably from 30% to 60% by mass.

-Thickness of coating liquid film-
The thickness of the coating liquid film formed in this step is not particularly limited and may be appropriately determined depending on the intended coating film.
The thickness of the coating liquid film can be selected, for example, from 10 μm to 200 μm, or from 20 μm to 100 μm, from the viewpoint of ease of cracking and curling.

The thickness of the coating liquid film is measured as follows.
That is, the coating liquid film was measured at three locations along the width direction (specifically, at a position 5 mm from both edges in the width direction and at the center in the width direction) using an optical interference type thickness measuring device, such as Keyence Corporation. Measured using an infrared spectroscopic interference type film thickness meter SI-T80. The arithmetic mean value of the measured values at three points is determined, and this value is taken as the thickness of the coating liquid film.

-Coating width-
The coating width in this step (that is, the width of the coating liquid film) is not particularly limited, but from the viewpoint of ease of curling, it can be selected to be 100 mm or more, and 1000 mm or more.
The upper limit of the coating width is the width of the support.

The coating width is measured as follows.
The width of the coating liquid film was measured from the upper surface of the coating liquid film using FALCIO-APEX776 manufactured by Mitutoyo Co., Ltd., and this was taken as the coating width.

-Application-
A known coating means is applied to apply the coating liquid in this step.
Specifically, the application means (for example, the application means 20 in FIG. 1) include a curtain coating method, a dip coating method, a spin coating method, a print coating method, a spray coating method, a slot coating method, a roll coating method, and a slide coating method. , a coating device using a blade coating method, a gravure coating method, a wire bar method, etc.

[Process B]
In step B, the coating liquid film obtained in step A is dried on a continuously conveyed support.
Then, in the constant rate drying stage of the coating liquid film in step B, while the solid content concentration of the coating liquid film is between 70% by mass and 95% by mass, the laminate consisting of the support and the coating liquid film is , starts curl control without contacting the coating liquid film.

Drying in this step refers to a period in which the coating liquid film formed in step A passes through a constant rate drying stage and a decreasing rate drying stage until it reaches a target solid content concentration.
Here, "constant rate drying" is a form of drying in which the content of the solvent (or dispersion medium) in the coating liquid film decreases over time.
Generally, a coating liquid film exhibits constant rate drying until a certain period of time has elapsed from immediately after its formation, and then exhibits decreasing rate drying. The time period indicating constant drying rate is described, for example, in Chemical Engineering Handbook (pages 707 to 712, published by Maruzen Co., Ltd., October 25, 1980).
In the present disclosure, the change over time in the film surface temperature at the center of the width direction of the formed coating liquid film is measured, and in the measurement of the film surface temperature immediately after application (immediately after the formation of the coating liquid film), the film surface temperature is A period in which a constant value is shown (specifically, a period in which the temperature change in the film surface temperature is within ±5° C.) is regarded as a “constant rate drying stage”.
After a period in which the membrane surface temperature shows a constant value, a period in which the membrane surface temperature increases is regarded as a "loss rate drying stage."
Note that the film surface temperature is measured using a non-contact radiation thermometer.

In step B, the drying temperature may be changed stepwise or continuously in the direction of conveyance of the coating liquid film. In this case, it is thought that the film surface temperature of the coating liquid film is also affected and changes. Therefore, in step B, the period in which the film surface temperature of the coating liquid film changes by the same amount as the amount of change in the drying temperature is included in the "period in which the film surface temperature shows a constant value."
That is, until the film surface temperature of the coating liquid film rises above the amount of change in the drying temperature, it is regarded as a constant rate drying stage.

The constant rate drying stage when the drying temperature in step B is constant will be explained in detail.
First, for the coating liquid film formed on the support, the change over time in the film surface temperature at the center in the width direction is measured, and the relationship between the measured film surface temperature and the elapsed time is determined, for example, by measuring the film surface temperature. Graph the vertical axis and elapsed time on the horizontal axis.
The obtained graph shows the period during which the film surface temperature shows a constant value (specifically, the temperature change in the film surface temperature) when measuring the film surface temperature immediately after coating (immediately after the formation of the coating liquid film). The period during which the temperature is within ±5°C is regarded as the constant rate drying stage.
Note that the point of change in the membrane surface temperature at which the membrane surface temperature begins to rise is defined as the end point of the constant rate drying stage. Note that the change point is determined from the intersection of a straight line extending the membrane surface temperature during a period showing a constant value toward the elapsed time side and a tangent line drawn at the point where the gradient of the membrane surface temperature is maximum.

- Curl regulation -
In this process, in the constant rate drying stage of the coating liquid film, while the solid content concentration of the coating liquid film is between 70% by mass and 95% by mass, the laminate consisting of the support and the coating liquid film is , starts curl control without contacting the coating liquid film.
In other words, in this process, the solid content concentration of the coating liquid film increases during the constant rate drying stage (that is, during the period when the film surface temperature shows a constant value), and after reaching 70% by mass, By the time the mass % is reached, curl control is started on the laminate consisting of the support and the coating liquid film without contacting the coating liquid film.
When the solid content concentration of the coating liquid film reaches 70% by mass, the solid content concentration is sufficiently high. (even if the surface is exposed), the occurrence of cracks can be suppressed.
On the other hand, by performing curl control before the solid content concentration of the coating liquid film reaches 95% by mass at the constant rate drying stage, compared to the case where curl control is performed after reaching the decreasing rate drying stage. , can enhance the curl regulation effect.
Furthermore, since the curl control performed in this step does not contact the coating liquid film, it does not come into contact with the surface of the coating liquid film that remains fluid during the constant rate drying stage. As a result, by controlling curl, it is possible to suppress the influence on the surface condition, properties, etc. of the surface of the coating liquid film.
Therefore, by controlling curling at the above-mentioned timing, a coating film in which cracks and curling are suppressed is formed.

Here, the solid content concentration of the coating liquid film was measured using an infrared spectroscopic interference type film thickness meter SI-T80 manufactured by Keyence Corporation. It can be determined by measuring the non-contact thickness until it forms a film.
Specifically, first, the non-contact thickness is measured from the time when the aqueous coating liquid is applied onto the support until the aqueous coating liquid becomes a dry film.
Next, the thickness of the dried film (dry film) is measured using a contact thickness meter. The measured dry film thickness is subtracted from the previously measured non-contact thickness to calculate the thickness of the solvent (or dispersion medium) in the coating liquid film at each measurement point.
By multiplying the obtained dry film thickness and solvent (or dispersion medium) thickness by their respective densities (dry film density and solvent density), the dry film per unit area of the coating liquid film at the measurement point can be calculated. Convert the weight and solvent weight to determine the solid content concentration.

The non-contact curl control used in this process is such that the widthwise end of the laminate of the coating liquid film and the support is curled toward the coating liquid film side without contacting the coating liquid film. There is no particular limitation as long as it is a means that can restrict warping (that is, warping).
From the viewpoint of excellent curl control ability, non-contact curl control is a means of jetting gas onto one or both sides of the laminate and continuously conveying the laminate while bending it in the thickness direction using the wind pressure of the gas (hereinafter referred to as curl control means). ) is preferably carried out.
The curl regulating means promotes drying (that is, increasing the solid content concentration) by ejecting gas to the laminate, and thus also functions as a part of the drying means.

- Curl regulating means The curl regulating means will be explained using FIGS. 2 and 3. 2 and 3 are schematic side views for explaining the curl regulating means in step B. FIG.
In FIGS. 2 and 3, 32 indicates a pre-curl control area, and 34 indicates a curl control area.
In the drying means 30A shown in FIG. 2, in the curl control region 34, gas is ejected onto one side of the laminate 12 (i.e., the surface on which the coating liquid film is formed), and the laminate is curved in the thickness direction by the wind pressure of the gas. A curl control means is used to continuously transport the paper while the paper is being transported.
In the drying means 30B shown in FIG. 3, gas is ejected onto both sides of the laminate 12 (i.e., the surface on which the coating liquid film is formed and the exposed surface of the support) in the curl control region 34, and the laminate is A curl regulating means is used that continuously conveys the material while curving it in the thickness direction.
According to such a curl regulating means, as shown in the schematic side views of FIGS. 2 and 3, the laminate 12 can be conveyed while being undulated in a wave-like manner. By conveying the laminate 12 while undulating in this manner, curl control is effectively achieved, and the effect of suppressing curl can be enhanced.
Note that the drying speed of the coating liquid film can also be controlled by adjusting the type of gas ejected from the curl regulating means, wind pressure, temperature, humidity, etc.
Further, the curl regulating means shown in FIGS. 2 and 3 have the same curl regulating ability.

The drying means 30A shown in FIG. 2 will be explained.
As shown in FIG. 2, the coating liquid film is dried by transporting the laminate 12 of the coating liquid film and the support through the drying means 30A.
In FIG. 2, in the pre-curl control area 32, the solid content concentration of the coating liquid film in the laminate 12 is increased, and in the curl control area 34, the solid content concentration of the coating liquid film on the support 12 is increased to 70% by mass. % to 95% by mass, curl control starts.

In the pre-curl control area 32 in FIG. 2, the solid content concentration of the coating liquid film in the laminate 12 is increased using a drying means (for example, a hot air blower) as described later.

In the curl control area 34 in FIG. 2, a plurality of conveyor rolls 36 are installed on the same plane on the support side, and on the coating liquid film side, between the installation positions of the conveyor rolls 36, there are jets that eject gas. A plurality of sections 38 are arranged on the same plane.
Gas (for example, air at 40° C.) is ejected from the spouting part 38 toward the laminate 12, and the conveying roll 36 rotates, so that the laminate 12 is conveyed while being curved in its thickness direction by the wind pressure of the gas. .

The drying means 30B shown in FIG. 3 will be explained.
As shown in FIG. 3, the coating liquid film is dried by transporting the laminate 12 of the coating liquid film and the support through a drying means 30B.
In FIG. 3, in the pre-curl control area 32, the solid content concentration of the coating liquid film in the laminate 12 is increased, and in the curl control area 34, the solid content concentration of the coating liquid film on the support 12 is increased to 70% by mass. % to 95% by mass, curl control starts.

In the pre-curl control area 32 in FIG. 3, the solid content concentration of the coating liquid film in the laminate 12 is increased using a drying means (for example, a hot air blower) as described later.

In the curl control region 34 in FIG. 3, a plurality of jetting portions 38a that jet gas toward the support are provided on the same plane. A plurality of jetting portions 38b are arranged on the same plane.
By spouting gas (for example, air at 40°C) from the spouting part 38a toward the laminate 12, and spouting gas (for example, air at 40°C) from the spouting part 38b toward the laminate 12, The stacked body 12 is conveyed while being curved in its thickness direction by the wind pressure of the gas.

The curl control area 34 in FIGS. 2 and 3 is located at a position where curl control starts while the solid content concentration of the coating liquid film of the transported laminate 12 is between 70% by mass and 95% by mass. That's fine.
The installation position of the curl control region 34 can be set based on the results of a study conducted in advance on the transition of the solid content concentration of the coating liquid film.
In addition, by determining the installation position of the curl control area 34 and adjusting the conveyance speed of the laminate 12 and the drying conditions of the pre-curl control area 32 as appropriate, it is possible to apply coating when the curl control area 34 is reached. The drying state of the coating liquid film may be controlled so that the solid content concentration of the liquid film is in the range of 70% by mass to 95% by mass.
Further, it is preferable that the end point of the curl control region 34 is, for example, up to the exit of the drying means 30A or 30B. That is, it is preferable that the curl control region 34 continues from the constant rate drying stage to the decreasing rate drying stage.

In the curl control region 34 in FIGS. 2 and 3, examples of the gas ejected toward the laminate 12 include air.
Further, the temperature of the ejected gas is preferably, for example, 25°C to 200°C, more preferably 30°C to 150°C.
Furthermore, the wind speed of the ejected gas is preferably, for example, 1.5 m/sec to 50 m/sec.
Furthermore, the amount of deformation of the laminate 12 in the curl control region 34 may be adjusted.
As shown in FIGS. 2 and 3, when the laminate 12 is viewed from the side, the amount of deformation of the laminate 12 is determined by the distance p between a ridge in the wavy undulating laminate 12 and an adjacent crest, and the crest in the laminate 12. and the height difference h between the valley and the valley. Note that the distance p is equivalent to the distance between the transport rolls 36 or the distance between the ejection parts 38b.
The distance p is, for example, preferably 100 mm to 1500 mm, more preferably 200 mm to 1000 mm.
Further, the height difference h is preferably 10 mm to 500 mm, more preferably 20 mm to 200 mm.
Further, the distance p/height difference h is preferably 10 or less, more preferably 5 or less, because the smaller the value, the higher the curl regulating force is. If the value of distance p/height difference h is decreased, the number or size of members in the curl control region 34 increases, so the lower limit value of distance p/height difference h is determined by equipment installation space, intake capacity, It is preferable to carry out an optimal design in consideration of costs and the like. The lower limit value of the distance p/height difference h is, for example, 2.

-Membrane surface temperature-
The membrane surface temperature in the constant rate drying stage is not particularly limited, and may be, for example, 35° C. or higher.

-Drying-
In this step, a known drying means is applied to dry the coating liquid film.
Specific examples of the drying means (eg, part of the drying means 30 in FIG. 1, drying in the pre-curl control area in FIGS. 2 and 3) include an oven, a hot air blower, an infrared (IR) heater, and the like.

By going through step B as described above, a coating film is formed on the support.

The thickness of the coating film obtained through step B is not particularly limited, and may be any thickness depending on the purpose, use, etc.
In the method for producing a coating film according to the present embodiment, since cracks and curls are likely to occur, the thickness of the coating film is preferably 40 μm or more, more preferably 50 μm or more, and 60 μm or more. It is more preferable to do so.
The upper limit of the thickness of the coating film is not particularly limited and may be determined depending on the application, and is, for example, 65 μm.
The measurement of the thickness of the coating film is the same as the measurement of the thickness of the coating liquid film.

[Other processes]
Before step A and at least one after step B, other steps may be included as necessary.
Other processes are not particularly limited, and include a pre-treatment process performed before applying the coating liquid film, and a post-treatment process performed on the formed coating film depending on the application of the coating film. It will be done.
Other steps include surface treatment of the support, curing of the coating film, compression of the coating film, cutting of the coating film, and removal of the support from the coating film. Examples include a step of peeling.

The method for producing a coated film according to the present embodiment is a method for producing a coated film on a support that is continuously conveyed, and therefore is suitable for producing a coated film for applications that require high productivity.

The present invention will be explained in more detail below by giving examples. The materials, amounts used, proportions, details of each step, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.
Note that all "parts" are based on mass.

<Preparation of support>
An aluminum support 1 (thermal conductivity: 230 W/(m·K)) having a width of 220 mm, a thickness of 10 μm, and a length of 300 m was prepared (abbreviated as AL1).
An aluminum support 2 (thermal conductivity: 230 W/(m·K)) with a width of 220 mm, a thickness of 30 μm, and a length of 300 m was prepared (abbreviated as AL2).

<Preparation of water-based coating fluid>
[Preparation of water-based coating fluids A1 and A2]
Aqueous coating liquid A was prepared by mixing the following components. Next, the aqueous coating liquid A was diluted with pure water to prepare an aqueous coating liquid A1 with a solid content concentration of 60% by mass and an aqueous coating liquid A2 with a solid content concentration of 30% by mass, respectively.
・Polyvinyl alcohol: 58 parts (CKS-50: degree of saponification 99 mol%, degree of polymerization 300, Nippon Gosei Kagaku Kogyo Co., Ltd.)
・Daiichi Kogyo Seiyaku Co., Ltd. Cellogen PR: 24 parts ・Surfactant (Nippon Emulsion Co., Ltd., Emmalex 710): 5 parts ・Aqueous dispersion of Art Pearl J-7P prepared by the following method: 913 parts

(Aqueous dispersion of Art Pearl J-7P)
3 parts of Emmalex 710 (Nippon Emulsion Co., Ltd., nonionic surfactant) and 3 parts of sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd.) are added and dissolved in 74 parts of pure water. To the obtained aqueous solution, 20 parts of Art Pearl (registered trademark) J-7P (Neagami Kogyo Co., Ltd., silica composite cross-linked acrylic resin fine particles) was added, and the mixture was heated at 10,000 rpm with an Ace homogenizer (Nippon Seiki Seisakusho Co., Ltd.). revolutions per minute (hereinafter the same applies) for 15 minutes to obtain an aqueous dispersion of Art Pearl J-7P (particle concentration: 20% by mass).
The true specific gravity of the silica composite crosslinked acrylic resin fine particles in the obtained aqueous dispersion is 1.20, and the average particle size is 6.5 μm.

[Preparation of water-based coating liquid B1]
The following components were mixed and stirred with a dissolver (2000 rpm, 30 minutes) to prepare aqueous coating liquid B (dispersion A: dispersion B = 25:75). The viscosity of the aqueous coating liquid B was 20 mPa·s, and the average particle size of the particles was 0.108 μm. Next, water-based coating liquid B was diluted with ion-exchanged water (or pure water) to adjust the solid content concentration to 30% by mass, and this was designated as water-based coating liquid B1.
・Dispersion A prepared by the following method: 132.1 parts ・Dispersion B prepared by the following method: 396.2 parts ・Boric acid (crosslinking agent): 2.94 parts ・Polyvinyl alcohol (7.3 parts by mass % aqueous solution): 230.7 parts (Kuraray Co., Ltd., PVA 235, degree of saponification 88%, degree of polymerization 3500)
・Diethylene glycol monobutyl ether: 2.7 parts (Butysenol 20-P, KH Neochem Co., Ltd.)
・Ion exchange water: 93.5 parts ・Polyoxyethylene lauryl ether (surfactant): 0.49 parts (10% aqueous solution of Emulgen 109P, HLB value 13.6, Kao Corporation)
・Ethanol: 41.4 parts

(Preparation of dispersion A)
After mixing the following components and subjecting them to ultrasonic dispersion, the dispersion liquid was heated to 30° C. and held for 8 hours to prepare dispersion A.
- Vapor-phase method silica fine particles (inorganic fine particles): 299.6 parts (AEROSIL 300SF75, Nippon Aerosil Co., Ltd.)
・Ion exchange water: 1400 parts ・Alphain 83 (40.0% aqueous solution): 300 parts (dispersant, Daimei Chemical Industry Co., Ltd.)

(Preparation of dispersion B)
After mixing the following components and subjecting them to ultrasonic dispersion, the dispersion liquid was heated to 30° C. and maintained for 8 hours to prepare dispersion B.
- Vapor phase method silica fine particles (inorganic fine particles): 225.2 parts (AEROSIL 300SF75, Nippon Aerosil Co., Ltd.)
・Ion exchange water: 1185 parts ・Cationic polymer A with the following structure (25% aqueous solution): 90 parts

[Example 1]
In an apparatus configured as shown in FIG. 1, a water-based coating liquid A1 is applied onto an aluminum support 1 (i.e., AL1) to form a coating liquid film, and the formed coating liquid film is It was dried to obtain a coating film.
Specifically, the aqueous coating liquid A1 was applied onto the continuously conveyed support AL1 with a coating width of 200 mm (Step A). The thickness of the coating liquid film formed is as shown in Table 1.
Subsequently, while transporting the laminate 12 of the coating liquid film obtained in step A and the support through the drying means 30A shown in FIG. The solution film was dried (Step B).
In the curl control area 34 in the drying means 30A shown in FIG. Continuous conveyance (Table 1 shows one-sided floating). The conditions for curl regulation in the curl regulation area 34 are as follows.
・Gas type: Air ・Gas temperature: 40℃
・Wind pressure of gas ejected onto the surface on which the coating liquid film is formed: 1.3 kPa
・Air volume of gas ejected onto the surface on which the coating liquid film is formed: 5 m ³ /min
- Amount of deformation of the laminate: distance p in Figure 2: 300 mm, height difference h in Figure 2: 60 mm, distance p/height difference h: 5
In addition, the solid content concentration of the coating liquid film when curl control was started is as shown in Table 1, and the solid content concentration of the coating liquid film when curl control was finished was 99% by mass. .
Note that the transport speed of the support in Step A and Step B was 3.0 m/min.
A coating film was formed through Step A and Step B as described above.

[Examples 2 to 15, Comparative Examples 1 to 10]
Except that the type of support, the type and solid content concentration of the coating liquid, the thickness of the coating liquid film, and the solid content concentration of the coating liquid film at the start of curl control were changed as appropriate as shown in Table 1. A coating film was formed in the same manner as in Example 1.

[Evaluation of cracks in coating film]
Measurement samples were cut out from the center portions of the coating films obtained in each example in the width and length directions. The size of the cut out measurement sample was a square of 50 mm x 50 mm.
The surface of the measurement sample was observed under a microscope with a magnification of 50 times to confirm the presence or absence of cracks with a diameter of 0.5 mm to 2 mm, and the cracks were evaluated using the following index.
-Evaluation index-
A: No cracks (i.e. no cracks)
B: A crack of 1 mm or less was confirmed (i.e., there was a crack)
C: A crack of more than 1 mm was confirmed (i.e., there was a crack)
The results are shown in Table 1.

[Evaluation of curl of coating film]
For the coating film obtained in each example, a measurement sample including the widthwise edge of the coating film was cut out from the center portion in the longitudinal direction. The cut out measurement sample had a rectangular size of 3.5 mm x 35 mm.
As shown in FIG. 4, the measurement sample (i.e., the laminate 14 of the coating film and the support) is placed on a flat table 40, and the portion corresponding to the widthwise edge of the coating film is raised. (That is, the amount of curl C) was measured at three locations, the arithmetic mean value of the values at the three locations was determined, and the curl was evaluated using the following index.
The measurements were conducted in an environment with a temperature of 23° C. to 25° C. and a relative humidity of 45% to 55%.
-Evaluation index-
A: Floating is 1 mm or less B: Floating is more than 1 mm and less than 2 mm C: Floating is more than 2 mm

As is clear from Table 1, it can be seen that according to the coating film manufacturing method of the example, a coating film with no cracks and less curling was formed.

The disclosure of Japanese Patent Application No. 2020-073689 filed on April 16, 2020 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference. Incorporated herein by reference.

10 support 12 laminate of coating liquid film and support 14 laminate of coating film and support 20 coating means 30, 30A, 30B drying means 32 pre-curl regulation area 34 curl regulation area 36 transport roll 38, 38a, 38b Spout part 40 units C Curl amount h Height difference between peak and valley (height difference of undulation)
p Distance between a mountain and the next mountain (distance between undulations)

Claims (5)

Step A of continuously conveying a long support and applying an aqueous coating liquid onto the continuously conveyed support;
Step B of drying the coating liquid film obtained in Step A on a continuously conveyed support;
including;
The thermal conductivity of the support is 200 W/(m・K) or more and 500 W/(m・K) or less,
The water-based coating liquid is a coating liquid containing particles,
The thickness of the coating liquid film is 10 μm to 200 μm,
In the constant rate drying stage of the coating liquid film in step B, while the solid content concentration of the coating liquid film is between 70% by mass and 95% by mass, the coating is applied to the laminate consisting of the support and the coating liquid film. A coating film manufacturing method that starts curl control without contacting the coating liquid film. The method for producing a coating film according to claim 1, wherein the solid content concentration of the coating liquid in step A is 30% by mass to 60% by mass. 2. The non-contact curl control is performed by blowing gas onto one or both sides of the laminate and continuously conveying the laminate while bending it in the thickness direction by the wind pressure of the gas. A method for producing a coating film. The method for producing a coating film according to any one of claims 1 to 3 , wherein the support is a metal support. The method for producing a coating film according to any one of claims 1 to 4 , wherein the support has a thickness of 10 μm to 30 μm.