JP2003170108A - Method and apparatus for preparing coating material in spray coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a coating material in which the excellent appearance of a coating film is attained by spray coating responding to the change of coating environment in a coating site, and an apparatus thereof. <P>SOLUTION: The method for preparing the coating material has (1) a process for previously obtaining a corresponding relation between the blending ratio of a fluid adjustment agent and a resonance resistance by changing the blending ratio of the fluid adjustment agent and spray-coating one surface of a crystal resonator to measure the resonance resistance in the coating material applied in the site, (2) a process for measuring the resonance resistance of the crystal resonator spray-coated with the coating material for site coating, (3) a process for obtaining the blending ratio of the fluid adjustment agent in order to control the resonance resistance of the crystal resonator measured in the process (2) to a proper range on the basis of the corresponding relation or the like between the blending ratio of the fluid adjustment agent and the resonance resistance obtained in the process (1) and (4) a process for adjusting the blending ratio of an additive in the coating material for site coating to the blending ratio of the fluid adjustment agent obtained in the process (3). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint adjusting method in a spray coating which uses a crystal oscillator in accordance with a coating environment and the like, and a paint adjusting device used in the paint adjusting method.

[0002]

2. Description of the Related Art When performing spray coating, rotary atomization coating, or electrostatic atomization coating in the air, if the humidity or temperature changes due to seasonal changes, or the wind speed in the booth changes, the coating machine will produce fine particles. Of the solvent volatilization speed of the sprayed paint particles until they reach the object to be coated, the solvent volatilization rate of the paint film applied to the object to be coated, and the particle size due to the mechanical conditions of the rotary atomizer. The change affects the viscoelastic properties of the coating composition, which leads to a decrease in the smoothness of the coating surface and causes poor appearance of the coating object such as cissing and sagging. Conventionally, in order to prevent these appearance defects, the paint manufacturer, depending on the season, mixes solvents with different volatilization rates depending on the season and characteristics of the coating equipment, or adds preset additives. We have supplied paints that we believe have the best coating properties. However, the adjustment method as described above does not cope with minute changes in the coating environment and the characteristics of the coating equipment, so that it is ultimately necessary to rely on the adjustment based on experience in the field. Also,
In the field of coating where excellent finish appearance is required, for example, in automobile exterior coating, when coating paints that are compatible with global environment conservation, especially water-based paints and high solids paints, Since it is difficult to control by adjusting the paint according to the change of the paint viscoelastic property after application due to the influence, it has been unavoidable to deal with it by finely controlling the paint environment and the properties of the paint equipment.

[0003]

A method for measuring the viscoelastic properties of a coating material applied to an object to be coated is to collect the coating material applied to the object to be coated, and then use a mechanical device such as a cone and plate. It is known to measure with a measuring instrument, or to paint on a plate and then quickly attach the plate to the measuring instrument to measure viscoelasticity.However, this method requires a very long measuring time and It is difficult to obtain accurate viscoelastic properties because the structure is destroyed during the collection and measurement of the coating composition.Because the measurement atmosphere is usually different from the on-site coating atmosphere, the viscoelastic characteristics of the coated film can be continuously and continuously measured in real time. It was difficult to grasp. It is an object of the present invention to provide a paint preparation method which can be carried out in a short time at a painting site in order to obtain a good paint film appearance in spray painting in response to changes in the painting environment. Another object of the present invention is to provide a paint adjusting device for carrying out this paint preparing method.

[0004]

The inventors of the present invention have applied a coating on a crystal oscillator, which is a highly sensitive sensor in an actual on-site coating environment, and change its resonance resistance depending on the coating environment atmosphere and the characteristics of coating equipment. The parameters corresponding to the viscoelastic properties of the coating material can be measured in a short time, and based on that data,
It was found that by adjusting the amount of additives in the coating within the range suitable for the on-site coating atmosphere, good coating work characteristics can be obtained even when the coating atmosphere changes, and the present invention is completed. It has come. That is, the present invention includes the following steps (1) to (4) (1) The coating composition to be applied on-site is spray-coated on one side of the crystal unit by changing the mixing ratio of the flow control agent, and the coated crystal vibration is applied. The step of measuring the resonance resistance of the child and obtaining the correspondence relationship between the mixing ratio of the flow control agent to be used and the resonance resistance in advance, (2) at the painting site, spray painting the on-site painting paint on one side of the crystal oscillator, The step of measuring the resonance resistance of the coated crystal unit, the step (3), the mixing ratio of the flow control agent for keeping the resonance resistance of the crystal unit measured in the step (2) within an appropriate range, Step based on the correspondence relationship between the blending ratio of the flow control agent obtained in 1) and the resonance resistance, the amount of flow control agent in the paint for on-site coating, and the resonance resistance of the crystal resonator measured in step (2) , And (4) For on-site paint filled in paint containers The present invention provides a coating material adjusting method in spray coating, which comprises the step of adjusting the blending ratio of the additive in the step (3) to the blending ratio of the flow control agent. Further, the present invention was measured with a paint container, a fluidity adjusting agent container connected to the paint container, a spray coating device for painting the paint from the paint container, an impedance analyzer for measuring the impedance of the crystal oscillator, and an impedance analyzer. Equipped with an arithmetic and control system that calculates the mixing ratio of the flow control agent in the paint to take the resistance component of the impedance at the resonance point as the resonance resistance and keep the resonance resistance of the coated crystal unit within the appropriate range. A device, based on the resonance resistance of the crystal resonator coated by the spray coating device, obtain the blending ratio of the flow control agent in the coating material to bring the resonance resistance of the coated crystal resonator within an appropriate range, Based on this blending ratio, a flow control agent can be blended from an additive tank to a paint container to provide a paint regulating device. . Hereinafter, the present invention will be described in detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The crystal oscillator is used for measuring time, temperature, pressure, film thickness, etc. When the crystal oscillator is in a solution, the resonance frequency depends on the viscoelasticity and density of the solution. Changes, and it is possible to investigate changes in the viscoelasticity and density of a solution. 17 (7)
p35-401989, "Ultrasonic TECHNO" vo
l. 5 (7) p45-501993.

In the method of the present invention, attention is paid to the fact that the resonance frequency and resonance resistance of the circuit change due to the characteristics of the viscoelastic substance attached to the surface of the crystal unit. By measuring the impedance at the resonance point of the crystal unit, the real-time component of impedance, that is, the resonance resistance, which is the resistance component, can be measured in real time. It is possible to grasp the viscoelastic properties of the applied coating film without breaking it. The method of the present invention is a paint preparation method in spray coating having the following steps (1) to (4). Step (1) In the step (1), with respect to the paint to be painted on-site, the mixing ratio of the flow control agent is changed, and spray coating is applied to one side of the crystal unit to measure the resonance resistance of the coated crystal unit. And the correspondence relationship between the mixing ratio of the flow regulator used and the resonance resistance,
For example, it is a step of previously obtaining a calibration curve, a relational expression, a relational diagram, and the like. The coating conditions for the above-mentioned coating are not particularly limited, but it is preferable that they are standard conditions for on-site coating. The above-mentioned flow control agent is used for a paint for on-site coating and affects the viscoelastic properties of the paint. As a typical example, for example,
Diurea-based fluidity regulator such as diurea, which is a reaction product of mono-primary amine and diisocyanate; ultrafine particulate barium sulfate, silica-based fine powder, bentonite-based regulator, polyamide-based regulator, water-based emulsion polymerization Examples thereof include crosslinked polymer fine particles and nonaqueous crosslinked polymer fine particles. It is preferable to coat the crystal unit so that one side surface of the crystal unit has a uniform film thickness of 1 μm to 100 μm, preferably 1 to 50 μm, from the viewpoint of obtaining uniform resonance resistance. is there. Further, it is preferable to measure the resonance resistance of the coated crystal unit about one minute after coating from the viewpoint of easy correspondence with the step (3) described later. That is, it is empirical that the state of the coating film of the coating film is determined by the expression of its viscoelastic property between 30 seconds and about 1 minute 30 seconds after the coating film is formed by spray coating, that is, after about 1 minute. It is well known that the optimum coating surface state can be obtained by controlling the flow characteristics due to the viscoelastic characteristics at that time.

Step (2) In the step (2), at the painting site, one side of the crystal unit connected to the impedance analyzer is spray coated with a paint for on-site coating, and the resonance resistance of the coated crystal unit is measured. It is a process to do. The coating on the crystal unit is performed so that the film thickness is uniformly 1 μm or more on one surface of the crystal unit. Also, the measurement of the resonance resistance of the painted crystal unit is
It is preferable to perform the coating after about 1 minute from the viewpoint of the ease of dealing with the step (3) described later and the above-mentioned aspect. This step (2)
Is generally performed at the stage of the test coating just before the main coating at the coating site, but in addition to this, it can be appropriately performed during the main coating depending on the change of the site coating environment.

Step (3) In Step (3), the mixing ratio of the flow control agent for adjusting the resonance resistance of the crystal unit measured in Step (2) to be within an appropriate range is obtained in Step (1). This is a step of obtaining based on the correspondence relationship between the blending ratio of the flow control agent and the resonance resistance, the amount of the flow control agent in the paint for on-site coating, and the resonance resistance of the crystal resonator measured in step (2). The suitable range of the resonance resistance, the coating applied to the spray coating is applied to the object to be dripped, cissing,
It means a range of resonance resistance corresponding to a range of viscoelastic properties of the coating composition that can obtain a good coating surface appearance without causing deterioration of smoothness. The suitability range of the resonance resistance does not vary greatly depending on the type of paint, and it is usually 7 to 13 KΩ, preferably 8 to 12 K after coating the crystal unit for about 1 minute.
Ω, particularly preferably 9 to 11 KΩ. To set the appropriate range of the resonance resistance, for example, in the step (1), at the same time as coating the crystal unit, other coated objects are coated, and the state of the coating film on the coated objects is judged. This can be done by setting the range of resonance resistance corresponding to the range in which a good paint film can be formed. The blending ratio X of the flow control agent for forming a good coating film can be obtained as follows, for example. Letting A be the resonance resistance measured in the step (2), the mixing ratio a of the fluidity modifier when the resonance resistance is A is obtained from the correspondence obtained in the step (1). When the suitable range of the resonance resistance is 7 to 13 KΩ, for example, when the resonance resistance is 10 KΩ which is the center value, the blending ratio b of the flow regulator corresponding to the resonance resistance 10 KΩ is obtained from the correspondence relationship obtained in the step (1). can get. Further, when the mixing ratio of the flow control agent in the on-site coating material used in the step (2) is c, the mixing ratio X of the flow control agent can be calculated by the following formula. X = (b−a) + c When a flow control agent is added to the coating composition for in-situ coating, the amount of c is already present in the coating composition, so the addition ratio is (b−a).
Becomes

Step (4) The step (4) is a step in which the mixing ratio of the flow control agent in the coating composition for on-site coating filled in the coating container is set to the mixing ratio of the flow control agent obtained in the step (3). Therefore, the amount of the flow control agent in the paint for on-site coating is adjusted so that a good paint film can be formed. The amount of the flow control agent in the paint for on-site coating may be automatically adjusted based on the mixing ratio X of the flow control agent obtained in the step (3). In the method of the present invention, by performing the above-mentioned steps (1) to (4), the amount of the flow control agent in the coating composition for on-site coating is adjusted so that the appearance of the coating film is appropriate when spray coating the coating composition on site. The amount can be adjusted so that sagging, cissing and deterioration of smoothness do not occur, and a good coated surface appearance can be obtained.

[0010]

EXAMPLES Next, the coating material adjusting device of the present invention will be described with reference to FIG. FIG. 1 is a model diagram showing an example of the basic configuration of the paint adjusting device of the present invention. An example of the paint adjusting device of the present invention and an example of the paint adjusting method of the present invention will be described with reference to FIG. The paint adjusting device of the present invention is a paint container, a flow control agent container connected to the paint container, a spray coating device for applying paint from the paint container, a crystal oscillator, an impedance analyzer for measuring the impedance of the crystal oscillator, In addition, the resistance component of the impedance at the resonance point measured by the impedance analyzer is taken in as the resonance resistance, and the mixing ratio of the flow control agent in the paint is calculated so that the resonance resistance of the coated crystal unit falls within the appropriate range. It is equipped with an arithmetic and control system.

In FIG. 1, the paint in the paint container is sent to a spray coating device, and the paint is sprayed from the spray coating device.
One side of the crystal unit is painted. An AT-cut crystal piece having a resonance frequency of 9 MHz is used for the crystal resonator that is the sensor. The coated crystal unit can measure the impedance at the resonance point of the crystal unit in real time with an impedance analyzer, and can obtain the resonance resistance. This resonance resistance corresponds to the viscoelastic property of the coating composition. During on-site coating, by measuring the resonance resistance in real time, it is possible to detect the viscoelastic characteristics of the coating composition depending on the environment and coating conditions at that time. Paint is applied to one side of the crystal unit.At this time, if the paint wraps around the back side of the crystal unit, it may cause a measurement error. It is fixed, and painting is performed with a window open on the sensor surface, which is one side of the crystal unit. For example, a mask may be used for painting. The resonance resistance at the resonance point of the coated crystal unit is measured by an impedance analyzer. The time from coating to measurement varies depending on the coating conditions of the line, but it is preferable to be about 1 minute from 30 seconds to 1 minute 30 seconds after the coating film is formed by spray coating. The impedance is measured one minute after the trigger is generated, and the resistance component of the impedance at the resonance point is set as the resonance resistance and set in the arithmetic and control system. As described above, in the method of the present invention, the correspondence relationship between the blending ratio of the flow control agent to be used and the resonance resistance of the coating material to be coated in the step (1) is obtained in advance.
Further, at the painting site of step (2), the resonance resistance of the crystal unit coated with the on-site painting paint can be obtained. The correspondence relationship between the mixing ratio of the flow regulator and the resonance resistance is
Usually, it can be expressed as a polynomial of second to third order. Further, in step (1), in order to obtain the correspondence relationship between the blending ratio of the flow control agent and the resonance resistance, the timing (time from the end of the coating film formation) for measuring the resonance resistance of the crystal unit and It is preferable to match the timing of measuring the resonance resistance of the crystal unit (the time from the end of the coating film formation). That is, in step (1), if the corresponding relationship is obtained by measuring the resonance resistance of the coated crystal unit 1 minute after the end of the paint film formation, in step (2), 1 minute after the end of the paint film formation. It is preferable to measure the resonance resistance of the later coated crystal oscillator.

In the arithmetic and control system, the correspondence relationship between the blending ratio of the flow control agent and the resonance resistance is preliminarily entered for various kinds of paint to be painted on-site. At the time of on-site painting, a crystal oscillator coated with the paint for on-site painting By inputting and calculating the resonance resistance of, and the mixing ratio of the flow control agent mixed in the paint for on-site coating, an appropriate resonance resistance corresponding to the viscoelastic properties of the coating paint showing good coating workability can be obtained. The mixing ratio X of the flow control agent and the addition ratio (ba) of the flow control agent can be determined. Based on the addition ratio (ba) of this flow control agent, the required amount of flow control agent is automatically controlled and added to the paint tank, and the mixture is stirred to make the paint in the paint tank uniform. Do the actual painting. By measuring the resonance resistance of the crystal unit coated with the paint for on-site coating at the test coating stage immediately before the main coating, it is possible to obtain a coating that matches the coating environment and coating conditions of the main coating.

It is desirable to adjust the amount of the flow control agent at the start of coating, and the amount of the paint in the paint tank should be at least the amount used within the day and should not be used as it is on the next day. It is preferable to add the above paint. The amount of the flow control agent can be adjusted not only at the start of coating but also during the coating according to changes in the coating environment and coating conditions. In some cases, in order to reduce the amount of the flow regulator in the paint tank, it is possible to add a paint having a small amount or no flow regulator. Viscoelasticity adjustment of coating paint In spray coating, the viscoelasticity of the coating liquid that has been atomized and applied to the surface of the object to be coated is the coating environment, coating conditions, degree of atomization, degree of solvent evaporation, etc. Therefore, even if the viscoelastic property of the coating liquid before atomization is measured, the viscoelastic property of the paint applied to the object to be coated cannot be estimated.

It is necessary to measure the viscoelastic properties which actually affect the coating workability without destroying the structural viscosity of the applied coating film. In addition, even with paints of the same composition, the viscoelastic behavior that develops during application will differ subtly depending on the atmosphere at the site, the characteristics of the coating equipment, and the like. In the method of the present invention, the resonance resistance corresponding to the viscoelastic property of the coating material applied to the surface of the crystal oscillator is generally 7 to 13 after 1 minute from the application.
kΩ, preferably 8 to 12 kΩ, particularly preferably 9 to 1
It has been empirically confirmed that it is preferably within the range of 1 kΩ, and a paint adjusted to have a resonance resistance of 10 kΩ one minute after application has good workability and proper finishability. Obtainable. The correspondence relationship between the blending ratio of the fluidity adjusting agent and the resonance resistance of the paint to be painted on site can be determined by the following experiment, for example. Using an electrostatic coating device or a similar device that is actually used in the field, the environmental atmosphere is adjusted to a temperature of 25 ° C. ± 3 ° C. and the humidity is adjusted to 60 to 70%. A single side of the crystal unit is coated with a paint for in-situ coating to which the minimum necessary flow control agent is added, and the resonance resistance value 1 minute after the completion of coating is measured. After that, for 100 parts by weight of resin in the paint,
The flow control agent is added by changing the addition amount in increments of 0.5 part by weight, and the same measurement is performed. Finally, the total amount of the flow control agent is measured in the same manner until the blending ratio becomes 10 to 20 parts by weight with respect to 100 parts by weight of the resin content, and the resonance resistance of the crystal unit 1 minute after the completion of coating Measure and record.
The following table shows an example of the value of the resonance resistance with respect to the blending ratio of the flow control agent.

[0015]

[Table 1]

The calibration curve obtained from this experiment and showing the correspondence relationship between the blending ratio Y of the flow control agent and the resonance resistance Z is generally expressed by the following linear equation. Y = 0.0009Z-1.0399 Additivity is established between the mixing ratio of the flow control agent and the change in resonance resistance, and the resonance resistance at the time of application calculated from the above equation is 10 k.
From the ratio of the flow control agent for adjusting to Ω, the resonance resistance measured by the test coating of the in-situ coating paint, and the ratio of the flow control agent already contained in the in-situ coating paint, the environment of the coating site The required amount of the flow regulator is calculated in step 1, and the flow regulator of this blend amount is automatically added to the coating liquid tank by a metering pump, and after sufficient stirring and stabilization, the test coating is performed again to approximately 10 kΩ. After confirming that the resonance resistance has been reached, apply the main coating.

[0017]

According to the method of the present invention, it is possible to measure the viscoelastic property of the coating composition in the coating environment atmosphere in a short time by coating the crystal unit which is a highly sensitive sensor in the actual field coating environment and the resonance resistance. Based on that data, the amount of additives in the paint can be adjusted to a value within the appropriate range for the on-site painting atmosphere, and even if the painting atmosphere changes, good painting work characteristics can be obtained in real time. Obtainable

[Brief description of drawings]

FIG. 1 is a model diagram showing an example of a basic configuration of a paint adjusting device of the present invention.

Claims (8)

[Claims] 1. The following steps (1) to (4) (1) With respect to the coating material to be painted on-site, spraying is applied to one side of the crystal unit by changing the mixing ratio of the flow control agent, and the coated crystal vibration is applied. The step of measuring the resonance resistance of the child and obtaining the correspondence relationship between the mixing ratio of the flow control agent to be used and the resonance resistance in advance. (2) At the painting site, spray paint the on-site painting on one side of the crystal oscillator, The step of measuring the resonance resistance of the coated crystal unit, (3) the step of adjusting the mixing ratio of the flow control agent to bring the resonance resistance of the crystal unit measured in the step (2) into an appropriate range. Step based on the correspondence relationship between the blending ratio of the flow control agent obtained in 1) and the resonance resistance, the amount of flow control agent in the paint for on-site coating, and the resonance resistance of the crystal resonator measured in step (2) And (4) In the paint for on-site painting filled in the paint container And a step of setting the blending ratio of the fluidity adjusting agent according to step (3) to the blending ratio of the fluidity controlling agent determined in step (3). 2. The paint preparation according to claim 1, wherein in step (2), the impedance of the crystal unit is measured by an impedance analyzer, and the resistance component of the impedance at the resonance point is the resonance resistance. Method. 3. A film thickness of 1 μm to 100 μm obtained by applying a coating material for in-situ coating on one surface of the crystal unit in the step (2).
3. The coating material adjusting method according to claim 1, wherein the coating film is formed, and the resonance resistance of the crystal unit is measured about 1 minute after coating. 4. In the step (3), the suitable range of the resonance resistance is 7 after the coating of the coating on the crystal unit with the resonance resistance.
The coating preparation method according to any one of claims 1 to 3, wherein the coating preparation method is in the range of 13 kΩ to 13 kΩ. 5. The method according to claim 1, wherein in step (4), the amount of the fluidity adjusting agent in the coating composition for on-site coating is adjusted by automatic control so that the flow adjusting agent has a predetermined ratio. The paint preparation method according to item. 6. The coating of the paint on one surface of the crystal unit is performed with a window opened in a portion of the sensor surface which is one side of the crystal unit fixed in the hollow of the case. The paint preparation method described in any one of 1. 7. The step (1) and the step (2), wherein the time from the completion of coating film formation on one surface of the crystal unit to the time of measuring the resonance resistance is the same. The paint preparation method described in. 8. A paint container, a fluidity adjusting agent container connected to the paint container, a spray coating device for painting paint from the paint container, an impedance analyzer for measuring the impedance of a crystal oscillator, and a resonance measured by the impedance analyzer. A device equipped with an arithmetic and control system that takes in the resistance component of the impedance at the point as resonance resistance and calculates the mixing ratio of the flow regulator in the paint so that the resonance resistance of the coated crystal unit falls within the appropriate range. Which is based on the resonance resistance of the crystal resonator coated by the spray coating device, and obtains the blending ratio of the flow control agent in the paint for keeping the resonance resistance of the coated crystal resonator within the appropriate range. A paint adjusting device characterized by adding a flow adjusting agent from an additive tank to a paint container based on a mixing ratio.