JPH1180602A - Preparation of powder slurry coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing a powder slurry coating which can eliminate the need to provide the step of grinding and can improve heat stability and the appearance of coatings by comprising mixing a water dispersion of a curing agent with a water dispersion of fines particles of a resin prepd. by mixing a resin melt contg. a synthetic resin for a powder coating with an aq. medium. SOLUTION: A resin melt obtd. by heat-melting a, kneaded product of a synthetic resin for a powder coating and optionally a photoinitiator and a color pigment is mixed with an aq. medium heated to a temp. around the softening point of the resin under pressure. The resin melt is mechanically emulsified and dispersed in the aq. medium while maintaining the mixture at a temp. around the softening point of the resin. The system is rapidly cooled to obtain a water dispersion (A) of fines particles of the resin. Separately, a melt of a curing agent obtd. by heat melting a curing agent is mixed with an aq. medium heated to a temp. around the softening point of the curing agent. The melting of the curing agent is mechanically emulsified and dispersed in the aq. medium while maintaining the mixture at a temp. around the softening point of the curing agent. The system is rapidly cooled to obtain a water dispersion (B) of fine particles of the curing agent. Next, the component A is mixed with the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powder slurry paint used in the technical field of paint and the like.

[0002]

2. Description of the Related Art Methods for producing powder coatings and the like include a wet method and a dry method. In the wet method, a paint is made in almost the same way as a normal solvent-based paint, and then the solvent is distilled off and pulverized. A method of spraying the powder into the powder and removing the solvent at the same time has been performed. However, it is not practically used because it has many technical problems and the cost is higher than the latter at present.

[0003] The dry method comprises various steps of mixing, heating, melting and kneading various raw materials, and further cooling, pulverizing and classifying. Further development is expected in the future as a paint that does not use organic solvents. However, the following problems are listed in the dry method.

[0004] 1) In a powder coating containing a resin and a curing agent as main raw materials, in a step of kneading a material obtained by pulverizing the curing agent to several tens of microns with a resin or the like, to maintain heat stability, Since the temperature must be lower than the softening point of the agent, sufficient kneading cannot be performed, and the appearance of the coating film is poor.

[0005] 2) Powder coatings produced by the dry method must be irregular in shape, and especially in the case of powder coatings having a volume average diameter of 20 microns or less, the fluidity as a powder is poor. Extremely worse.

[0006] 3) The smaller the particle size of the powder, the more the pulverizing energy required per powder weight is drastically increased, resulting in an increase in cost. In recent years, the trend of powder coatings is that the average particle size of powder coatings is becoming smaller and smaller due to the demand for improved surface smoothness and gloss. However, it is very difficult to produce the powder coating by the conventional pulverization method, and even if it can be performed, the cost is high.

[0007] It is very difficult to overcome the above problems by a wet method or a dry method. The powder slurry coating of the present invention is conventionally produced by dispersing the powder coating obtained above in an aqueous medium.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a powder slurry coating material which solves the problem by radically improving the conventional method when producing a powder coating material containing a resin and a curing agent as raw materials. It is an object of the present invention to provide a production method of

Specifically, in the present invention, a resin or the like and a curing agent are separately heated and melted, so that the problem of thermal stability can be avoided and the production is easy.
And since it can be easily heated and melted to a temperature above the softening point of each of the resin and the curing agent, it becomes a slurry of ultrafine particles,
The appearance of the coating film is improved.

The present invention provides a method for producing a spherical powder slurry paint which does not require a costly pulverizing step in a dry process. The present invention provides a simple and highly productive continuous production method capable of easily producing powder coating of ultrafine particles of 10 microns or less.

The present invention provides a production method which does not require equipment such as a powder coating line and can be introduced with almost no modification in an existing water-based coating line.

[0012]

Means for Solving the Problems The present inventors have proposed a method for producing a powder coating containing a resin and a curing agent as main raw materials.
As a result of intensive trials and examinations as to whether a powder coating having both the merits of the dry method using no organic solvent and the merits of the spherical, fine-grain powder coating of the wet method could be repeated, the raw materials such as resin and the curing agent were used. It has been found that the above-mentioned problems can be achieved by producing powder slurries separately for each of the above, and the present invention has been completed.

That is, the present invention provides a resin melt (a) obtained by heating and melting a kneaded product of a synthetic resin for powder coating and, if necessary, a photoinitiator and a coloring pigment, And further mixed with the aqueous medium (b) heated to a temperature around the softening point of the synthetic resin by further applying pressure, while maintaining the temperature of the mixture at a temperature around the softening point of the synthetic resin,
The resin melt (a) is emulsified and dispersed in an aqueous medium (b) by mechanical means, and then immediately cooled rapidly to obtain an aqueous dispersion (c) of resin fine particles and a curing agent, thereby heating and melting. And the aqueous medium (e) heated to a temperature around the softening point of the curing agent by heating and, if necessary, further pressurizing, and mixing the mixture with the aqueous medium (e). While maintaining the temperature around the softening point of the curing agent, the curing agent melt (d) is emulsified and dispersed in an aqueous medium (e) by mechanical means, and then immediately cooled rapidly to obtain the curing agent fine particles. It is intended to provide a method for producing a powder slurry coating, characterized by mixing with an aqueous dispersion (f), wherein the synthetic resin for powder coating preferably comprises an acrylic resin, an epoxy resin, or a polyester resin. Select from group A method for producing a powder slurry coating comprising at least one resin, wherein a ring-shaped stator having slits and a ring-shaped rotor having slits are preferably provided as a mechanical means for emulsification and dispersion. Using a high-speed rotation type continuous emulsifying and dispersing machine provided coaxially so that the stator and the rotor engage with each other, preferably with a synthetic resin for powder coating, and start light if necessary. A mixture of a resin melt obtained by heating and melting a kneaded material with a coloring pigment, or a curing agent melt obtained by heating and melting a curing agent, and an aqueous medium, into the high-speed rotation type continuous emulsifying and dispersing machine. The mixture is supplied, and the mixture is caused to flow in a centrifugal direction from the inner core of the rotor through the slit and the gap by the high-speed rotation of the rotor, and a shear force is generated while passing through the slit of the stator and the slit of the rotor. Give By applying shear stress while the mixture passes through the gap between the stator and the rotor, the resin melt is emulsified and dispersed in an aqueous medium, while the hardener melt is dispersed in an aqueous medium in the same manner. Disclosed is a method for producing a powder slurry paint which is emulsified and dispersed in a medium and then mixed with both aqueous dispersions.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention produces an aqueous dispersion in which fine resin particles are dispersed in an aqueous medium without using a solvent and an aqueous dispersion in which fine particles of a curing agent are dispersed in an aqueous medium. This is a method for producing a powder slurry paint (water emulsification dispersion method), which comprises mixing an aqueous dispersion, and includes three steps. The first step and the second step are the production of an aqueous dispersion of particles of resin and the like and the production of an aqueous dispersion of hardener particles, and the third step is a step of mixing both aqueous dispersions.

First, the first step of the present invention will be described.
That is, in the first step, a resin melt (a) obtained by heating and melting a kneaded product of a synthetic resin for powder coating material, and, if necessary, a photoinitiator and a coloring pigment, is heated, and further, if necessary. An aqueous medium (b) heated to a temperature around the softening point of the synthetic resin by pressurization is mixed, and while maintaining the temperature of the mixture at a temperature around the softening point of the synthetic resin, the resin melt ( This is a step of producing an aqueous dispersion (c) of fine resin particles by emulsifying and dispersing a) in an aqueous medium (b) by mechanical means and then immediately cooling the mixture.

The synthetic resin for powder coating used in this step is:
Any material may be used as long as it is suitable for a powder coating. For example, acrylic resins, epoxy resins, amine-modified resins, phenol resins, xylene resins, polyester resins, urea resins, urethane resins, blocked isocyanate resins, and mixtures thereof, and the like. Of these, acrylic resins, polyester resins, and epoxy resins are preferred.

The photoinitiator can be any one which is suitable for powder coatings. Examples of the photoinitiator include acetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin isobutyl ether, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-dimethyl-1-phenylpropan-1-one,
-(4-isopropylphenyl) -2-hydroxy-2
-Methylpropan-1-one, azobisisobutylnitrile, benzoyl peroxide, di-tert-butyl peroxide and the like. The commercially available benzyldimethyl ketal includes Irgacure-651 (manufactured by Ciba-Geigy), and the commercially available 1-hydroxycyclohexylphenyl ketone includes Irgacure-184 (manufactured by Ciba-Geigy).

In addition to the photoinitiator, a coloring pigment or the like can be added to the synthetic resin, if necessary. Examples of the coloring pigment include an organic pigment and an inorganic pigment. Examples of the organic pigment include an azo pigment, a phthalocyanine pigment, a condensed polycyclic pigment, a nitroso pigment, and the like.Examples of the inorganic pigment include an oxide pigment, a phthalocyanine compound,
Chromate pigments, carbon pigments, mica pigments, metal powder pigments and the like can be mentioned. These pigments may be coated with a pigment dispersant.

In addition, as additives, fillers, rust inhibitors, ultraviolet stabilizers, ultraviolet absorbers, flow regulators, cissing inhibitors and the like are added as required. The above raw materials are kneaded and melted by heating to produce a resin melt. Specifically, a synthetic resin, and if necessary, a photoinitiator, a color pigment, and an additive are dry-blended by a mixer, then completely melted in a heating and melting tank equipped with a stirrer, and sent to a resin melt tank.

Next, the aqueous medium of the present invention will be described.
Generally, the aqueous medium is basically water, and if necessary, a dispersant and a surfactant may be added in order to form a stable aqueous dispersion of the resin melt. As the dispersant, for example, polyvinyl alcohol, which is often used in suspension polymerization of styrene, a water-soluble polymer dispersion stabilizer such as hydroxyethyl cellulose, or a poorly water-soluble inorganic dispersion stabilizer such as calcium phosphate, etc. Any of these may be used. Examples of the surfactant include 2,6,8-trimethyl-4-nonyloxypolyethyleneoxyethanol and the like.

The ratio of the aqueous medium to the synthetic resin must be an amount sufficient to produce an aqueous emulsion dispersion. The solvent-free water emulsification dispersion method of the present invention is characterized in that the synthetic resin melt and the aqueous medium are heated to a temperature around the softening point of the resin. The temperature around the softening point is not particularly limited, but is preferably a temperature within ± 30 ° C. of the softening point in order to maintain the synthetic resin in a molten state.

The above-mentioned aqueous medium is a high-temperature aqueous medium which is heated and optionally pressurized. By using a heat exchanger for heating or the like, the synthetic resin for powder coating is heated to a temperature around the softening point of the synthetic resin in order to melt it. Therefore, the aqueous medium, the softening point of the synthetic resin used, pressured by 1Kg / cm ² ~20Kg / cm ² of about pressurizing means provided in the process, is adjusted to proper temperature. In particular, when the softening point of the synthetic resin is low, it is not always necessary to use a pressurizing means. However, when the softening point is 100 ° C. or higher, it is necessary to pressurize the aqueous medium so as not to boil.

Next, immediately after mixing the resin melt obtained in the above step with the high-temperature aqueous medium, the resin melt is mechanically emulsified and dispersed in the aqueous medium. As an apparatus for mechanically emulsifying and dispersing a resin melt in an aqueous medium, a ring-shaped stator having a slit and a ring-shaped rotor having a slit are maintained with a slight gap, and the stator and the rotor are rotated. It is preferable to use a high-speed rotation type continuous emulsifying and dispersing machine having a structure provided coaxially so that the daughters bite each other.

The high-speed rotation type continuous emulsifying and dispersing machine of the present invention continuously injects a resin melt and a high-temperature and high-pressure aqueous medium, and at a temperature around the softening point of the synthetic resin, the decomposition temperature of the synthetic resin. It is a device with a structure that can be rapidly and uniformly mixed, emulsified and dispersed under the following high temperature and high pressure, and continuously discharged.

The high-speed rotation type continuous emulsifying and dispersing machine can emulsify and disperse a synthetic resin melt in an aqueous medium by rotating the rotor at a high speed. It is necessary to heat the temperature of the emulsifying and dispersing machine in order to maintain the synthetic resin in a constant molten state. Therefore, it is preferable that the emulsifying and dispersing machine be provided with a jacket for keeping the temperature. The optimum temperature of the synthetic resin varies depending on the particle diameter of the target particles, the molecular weight of the resin, and the like, but is preferably set to 80 ° C to 220 ° C.

The temperature in the high-speed rotation type continuous emulsifying and dispersing machine is as follows:
Temperature of the resin melt to be supplied, temperature of the aqueous medium to be supplied,
The temperature is controlled to be constant by the balance between the heat retention effect of the jacket and the amount of heat generated by the shearing force inside the machine.

The pressure in the high-speed rotary type continuous emulsifying and dispersing machine is determined by the vapor pressure of the aqueous medium at the machine temperature and the discharge pressure by the pump function of the rotor. Usually, it is preferable to provide an automatic pressure control valve after cooling the aqueous dispersion of resin fine particles, keep the internal pressure constant, and continuously take out the aqueous dispersion under atmospheric pressure.

In the high-speed rotation type continuous emulsifying and dispersing machine, a mixture of a resin melt and a high-temperature aqueous medium is supplied to a high-speed rotation type continuous emulsifying and dispersing machine, and the mixture is rotated by the high-speed rotation of the rotor. It flows in a centrifugal direction from the inner core of the rotor through the slit and the gap, and applies a shearing force while passing through the slit of the stator and the slit of the rotor, and the mixture is formed between the stator and the rotor. By applying shear stress while passing through the gap between them, fine dispersion is achieved. The stator and rotor slits are nozzles,
Since a similar effect can be obtained, both the stator and the rotor, or one of the slits can be changed to a nozzle.

The high-speed rotation type continuous emulsifying and dispersing machine preferably used for mechanical fine dispersion of the present invention will be described below with reference to the drawings. The stator 1 of the high-speed rotation type emulsifying and dispersing machine is fixed at the same center, and the center thereof is connected to the liquid inlet 2 communicating with the raw material inlet.
It is open. On the circular surface of the stator 1, ring-shaped projections 3 which are concentric with the stator and are provided in multiple stages of one stage or two or more stages. A circumferential groove 4 is formed in the gap between the projections, and a plurality of slits 5 are formed in each projection. The width of these slits is 0.6 mm
~ 3.0 mm, and the slit is 12
There are up to 72 comb-shaped teeth. The width of the slit is preferably smaller toward the outer periphery of the projection in order to reduce the particle diameter of the supplied liquid.

A driving shaft 6 is provided at the center of the other inner wall in the high-speed rotating type continuous emulsifying and dispersing machine, and is connected to a driving unit to rotate at high speed. The rotor 7 of the high-speed rotation type continuous emulsifying and dispersing machine is fixed to the tip of the driving unit in parallel with the stator and on the same central axis. On the opposing surface of the rotor facing the stator, there are provided one or two or more multistage projections 8 which are concentric with the rotor and annular. As in the case of the stator, each rotating projection has a circumferential groove 9 formed in the gap between the projections, and a plurality of slits 10 formed in each projection.

The stator 1 and the rotor 7 are engaged with each other while the protrusion 3 and the circumferential groove 4 of the stator, the protrusion 8 and the circumferential groove 10 of the rotor are inserted while maintaining a small gap. Served for use.

In the high-speed rotation type continuous emulsifying and dispersing machine used in the present invention, a mixture of the resin melt and the high-temperature and high-pressure aqueous medium is supplied to the gap formed by the engagement, and the mixture is centrifuged from the inner core of the rotor. Flows in the direction, undergoes shearing force due to the high speed rotation of the rotor, and undergoes shear stress while the mixture passes through the gap between the stator and the rotor, thereby causing the resin melt to move in the aqueous medium. Is emulsified and dispersed.

When the rotor 7 rotates at a high speed, the resin melt and the high-temperature and high-pressure aqueous medium supplied to the main liquid inlet 2 of the high-speed rotary type continuous emulsifying and dispersing machine enter slits of protrusions of the innermost rotor. Is discharged from the outer circumference of the rotor projection by centrifugal force, pressed against the innermost stator projection, and enters the slit of the stator projection. The liquid mixture entering this slit is pushed by the mixture entering the slit of the innermost rotor by centrifugal force and is pushed out into the circumferential groove of the second rotor. At this time, the mixture is formed by the protrusion of the innermost stator and the second
Shear force can be applied by the rotor projections,
Shear stress is applied along the passage between the stator and the rotor. When the mixed liquids join together, further shearing force is applied, and the mixture is pushed by the subsequent mixed liquid and enters the slits of the projections of the second stator, and the mixture is sequentially moved in the centrifugal direction while repeatedly receiving the same as described above. The emulsification and dispersion are completed.

The relationship between the flow of the mixture and the shearing force and shear stress is as shown in FIG. The rotation speed of the rotor of the high-speed continuous emulsifying and dispersing machine is controlled by a drive motor connected to a drive shaft. The larger the rotation speed and the higher the peripheral speed, the greater the shearing force, and the smaller the particle size of the synthetic resin. Using a 10 cm diameter rotor, the preferred speed is 3,000-10,000 rpm.

An example of an apparatus commercially available as the high-speed rotation type continuous emulsifying and dispersing machine of the present invention is Cavitron (Eurotech Co., Ltd.). Next, the aqueous dispersion of the resin fine particles obtained from the outlet of the high-speed rotation type continuous emulsifying and dispersing machine is mixed with the glass transition of the synthetic resin as quickly as possible while the generated resin particles do not collide with each other and generate aggregates. Cools rapidly to a temperature below the temperature.

As a device for rapidly cooling, a commercially available heat exchanger can be used, and cooling is performed while exchanging heat with cooling water. The cooling rate is not particularly limited, but is preferably 10 ° C./sec or more in order to prevent generation of aggregates.

After the synthetic resin is rapidly cooled to around the glass transition temperature, the pressure is returned to atmospheric pressure by a pressure control valve to obtain a slurry of fine resin particles.
Next, the second step of the present invention will be described.

That is, in the second step, the curing agent melt (d) obtained by heating and melting the curing agent was heated, and further heated, if necessary, to a temperature around the softening point of the curing agent. An aqueous medium (e) is mixed and the hardener melt (d) is emulsified in the aqueous medium (e) by mechanical means while maintaining the temperature of the mixture at a temperature around the softening point of the hardener. This is a step of obtaining an aqueous dispersion (f) of fine particles of the curing agent by dispersing and immediately cooling the dispersion immediately.

The curing agent used in this step may be any one as long as it is suitable for a powder coating. First
It is necessary to have a functional group that reacts with the synthetic resin for powder coating used in the process, and it differs depending on the type of the synthetic resin. Examples of the curing agent include polycarboxylic acids (such as dodecane diacid and trimellitic acid), amino resins, block polyisocyanates, polyepoxides, and polyols.

The method for producing a hardener melt by fusing the hardener is the same as in the first step of producing the above resin melt. The aqueous medium, the method of emulsification and dispersion by mechanical means, and the method of rapid cooling are the same as those in the first step.

Next, the third step of the present invention will be described.
That is, this is a step of mixing the aqueous dispersion of the resin fine particles and the aqueous dispersion of the hardener fine particles at a predetermined ratio, and adding a viscosity modifier as necessary.

The mixing ratio of the aqueous dispersion of the resin fine particles and the aqueous dispersion of the hardener fine particles is not particularly limited, and differs depending on the type of the synthetic resin. Examples of the viscosity modifier include an acrylic resin and the like, and specific products include Primal ASE-60 (manufactured by Nippon Acrylic Chemicals).

An example of the flow from the first step to the third step will be described with reference to FIG. That is, the pump 13 is moved from the tank 12 containing the resin melt produced by the above method.
At the same time, the resin melt is supplied to the high-speed rotation type continuous emulsifying and dispersing machine 11 through the, and a high-temperature aqueous medium is obtained from the aqueous medium tank 14 containing the aqueous medium through the heat exchanger 15 for heating. The mixture is supplied to the high-speed rotation type continuous emulsifying and dispersing machine 11 through the line 16. The resin melt and the high-temperature aqueous medium are emulsified and dispersed in the emulsifier / disperser 11 to obtain a resin melt aqueous dispersion. This aqueous dispersion is immediately cooled by passing through a cooling heat exchanger 17, and sent to a resin slurry tank 19 via a pressure adjusting valve 18. The pressure in all steps of the resin flow is adjusted by the pressure adjusting valve 18.

Similarly, the hardener melt is supplied from a tank 22 containing the hardener melt produced by the above-described method to a high-speed rotary type continuous emulsifying and dispersing machine 21 via a pump 23, and at the same time, an aqueous medium is charged. A high-temperature aqueous medium is obtained from a heated aqueous medium tank 24 through a heating heat exchanger 25, and the high-temperature aqueous medium is supplied to a high-speed rotation type continuous emulsifying and dispersing machine 21 via a pump 26. The hardener melt and the high-temperature aqueous medium are emulsified and dispersed in the emulsifier / disperser 21 to obtain a hardener melt aqueous dispersion. The aqueous dispersion is immediately cooled by a heat exchanger 27 for cooling.
And is sent to a hardener slurry tank 29 via a pressure adjusting valve 28. The pressure of the entire flow of the curing agent is adjusted by the pressure adjusting valve 28.

The method for producing a powder slurry paint of the present invention comprises:
A series of steps from a resin melt and a high-temperature aqueous medium to cooling through a high-speed rotary type continuous emulsifying and dispersing machine, and a series of steps from a curing agent melt and a high-temperature aqueous medium to cooling through a high-speed rotary type continuous emulsifying and dispersing machine And can be performed continuously. Of course, the process up to rapid cooling is a continuous process, and after obtaining the synthetic resin slurry and the curing agent slurry, the powder slurry tank 3 is passed from each of the slurry tanks 19 and 29 through the resin slurry pump 20 and the curing agent slurry pump 30.
1 and a viscosity modifier may be added as necessary.

According to the present invention, as described above, a mixture of a resin and a curing agent melt and a high-temperature and high-pressure aqueous medium is subjected to high shear force, shear stress and high-frequency pressure fluctuation by a high-speed rotary emulsifying and dispersing machine. Solvent-free emulsification and dispersion are performed by utilizing the stirring and crushing actions.

The controlling factors of the average particle size of the resin fine particles and the hardener fine particles to be formed are the rotation speed of the rotor of the emulsifying and dispersing machine and the temperatures of the synthetic resin, the hardener and the aqueous medium.
When the values of all these controlling factors are increased, the water dispersibility of the synthetic resin and the curing agent is increased, and the particle diameter of the synthetic resin fine particles and the curing agent fine particles is reduced.

[0048]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. All parts and percentages in the examples are on a weight basis.

Example 1 Production of slurry of fine particles of synthetic resin and the like 99.4 parts of Finedec A-207S (acrylic resin: manufactured by Dainippon Ink and Chemicals) and 0 of Acronal 4F (flow control agent: manufactured by BASF) were used. .6 parts were premixed with a mixer, completely melted in a heat melting tank with a stirrer, and then held in the resin melt tank of FIG. Cavitron CD1 while heating to 200 ° C. with a pump of No. 13.
010 was fed at a rate of 100 g / min. The ion exchange water (containing 0.1% of PVA) in the aqueous medium tank of FIG.
While heating to 180 ° C. with a heat exchanger, the mixture was fed into the Cavitron at a rate of 1 liter per minute. Rotor speed is 8
000 rpm, pressure was operated at 10 Kg / cm ^2, slurry prepared is taken out and cooled within 15 seconds to 65 ° C. from 180 ° C., an average particle diameter of 2 microns, a maximum particle size of 10 microns or less in substantially spherical resin particles A slurry was obtained.

Preparation of Slurry of Hardener Fine Particles 100 parts of dodecane diacid (hardener) are premixed with a mixer, completely melted in a heat melting tank with a stirrer, and then held in a hardener melting tank 22 in FIG. I do. Cavitron CD while heating to 140 ° C with a 23 hardener pump
The 1010 was fed at a rate of 100 g / min. 5 of FIG.
The ion-exchanged water (containing 0.1% of PVA) in the aqueous medium tank of No. 4 was fed into the Cavitron at a rate of 1 liter per minute while heating to 110 ° C. with a heat exchanger. The rotating speed of the rotor is 8000 rpm, the pressure is 2 kg / cm ² , and the produced slurry is cooled and taken out from 110 ° C. to 65 ° C. within 10 seconds, and has an average particle diameter of 2 μm and a maximum particle diameter of 10 μm or less. A slurry of substantially spherical hardener particles was obtained.

Mixing of Slurry of Synthetic Resin etc. and Slurry of Hardening Agent Slurry of synthetic resin etc. and hardening agent slurry are mixed at a ratio of 84:16, and this slurry is mixed with Primal ASE-60.
1% by weight (viscosity modifier: Nippon Acrylic Chemicals)
In addition, a substantially spherical powder slurry paint having an average particle size of 2 microns and a maximum particle size of 10 microns or less was obtained. The slurry paint was spray painted on cold rolled steel panels to a thickness of about 1 mil. This panel was pre-baked at 100 ° C. for 15 minutes and then baked at 150 ° C. for 20 minutes.
A transparent, hard and smooth coating film was obtained.

[0052]

According to the present invention, since the resin and the curing agent are separately heated and melted, the appearance of the coating film obtained by applying the powder slurry coating is good. In addition, it is possible to produce a curable powder slurry coating with a small particle size by an extremely easy and highly productive continuous process without using an organic solvent.Economical even for resins that could not be powdered by conventional pulverization means Can be powdered.

[Brief description of the drawings]

FIG. 1 is a perspective view of a stator and a rotor of a rotary continuous emulsifying and dispersing machine used in the present invention.

FIG. 2 is a diagram showing a cross section of a main part of a rotary continuous emulsifying and dispersing machine used in the present invention.

FIG. 3 is a diagram showing a combination state of a stator protrusion and a rotor protrusion when the AA ′ part of FIG. 2 is viewed from a side surface.

FIG. 4 is a diagram showing a force applied to a fluid flowing between a stator and a rotor due to rotation of the rotor of the rotary continuous emulsifying and dispersing machine used in the present invention.

FIG. 5 is an explanatory diagram of a method for producing a powder slurry paint according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Liquid inlet 3 Stator protrusion 4 Stator circumferential groove 5 Protrusion slit 6 Drive shaft 7 Rotor 8 Rotor protrusion 9 Rotor circumferential groove 10 Protrusion slit 11 Rotary continuous fine dispersion Machine 12 Resin melt tank 13 Resin pump 14 Aqueous medium tank 15 Heat exchanger for heating 16 Aqueous medium pump 17 Heat exchanger for cooling 18 Pressure control valve 19 Resin slurry tank 20 Resin slurry pump 21 Rotary continuous fine disperser 22 Curing Agent melt tank 23 hardener pump 24 aqueous medium tank 25 heating heat exchanger 26 aqueous medium pump 27 cooling heat exchanger 28 pressure control valve 29 hardener slurry tank 30 hardener slurry pump 31 powder slurry paint tank

Continued on front page (72) Inventor Noboru Kogoshi 4-16-15, Nagaura Station, Sodegaura City, Chiba Prefecture

Claims (5)

[Claims] (1) A resin melt (a) obtained by heating and melting a kneaded product of a synthetic resin for powder coating and, if necessary, a photoinitiator and a coloring pigment; The mixture is further mixed with the aqueous medium (b) heated to a temperature around the softening point of the synthetic resin by further applying pressure, and the mixture is melted while maintaining the temperature of the mixture at a temperature around the softening point of the synthetic resin. The body (a) is emulsified and dispersed in an aqueous medium (b) by mechanical means and then immediately cooled to obtain an aqueous dispersion (c) of resin fine particles, and (2) a curing agent, which is heated and melted. And the aqueous medium (e) heated to a temperature around the softening point of the curing agent by heating and, if necessary, further pressurizing, and mixing the mixture with the aqueous medium (e). While maintaining the temperature around the softening point of the hardener, the hardener melt (d) A powder slurry paint characterized by mixing (3) an aqueous dispersion (f) of hardener fine particles obtained by emulsifying and dispersing in an aqueous medium (e) by mechanical means and then rapidly cooling the mixture. Manufacturing method. 2. The production method according to claim 1, wherein a viscosity modifier is added after mixing the aqueous dispersion of resin fine particles (c) and the aqueous dispersion of hardener fine particles (f). 3. The method according to claim 1, wherein the synthetic resin for powder coating contains at least one resin selected from the group consisting of an acrylic resin, an epoxy resin, and a polyester resin. 4. As a mechanical means for emulsification and dispersion, a ring-shaped stator having a slit and a ring-shaped rotor having a slit are interposed between the stator and the rotor while maintaining a small gap. The method according to any one of claims 1 to 3, wherein a high-speed rotation type continuous emulsifying and dispersing machine provided coaxially is used. 5. A resin melt obtained by heating and melting a kneaded product of a synthetic resin for a powder coating material and, if necessary, a photoinitiator and a coloring pigment, or a curing agent melt obtained by heating and melting a curing agent. A mixture with an aqueous medium is supplied to the high-speed rotation type continuous emulsifying and dispersing machine, and the mixture is caused to flow in a centrifugal direction from the inner core of the rotor through the slit and the gap by the high-speed rotation of the rotor, By applying a shearing force while passing through the slit of the stator and the slit of the rotor, and applying a shear stress while the mixture passes through a gap between the stator and the rotor, the resin 5. A method according to claim 4, wherein the melt is emulsified and dispersed in an aqueous medium, and the hardener melt is emulsified and dispersed in an aqueous medium in the same manner, and the two dispersions are mixed.
The manufacturing method as described.