JP5358817B2 - Functional coating film electrostatic coating method and powder coating functional coating film forming building material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method that simply and definitely forms a functional coating of high weatherability by electrostatic coating. <P>SOLUTION: A polyester powder coating material and a fluoric powder coating material are dry-blended with a mixing ratio of 7:3, and after they are electrostatically coated onto a coating object, atmosphere heating is performed on the coating object. It appears that because the powder coating material is indefinite form, voids are formed between the powder coating materials in the electrostatically-coated powder coating material layer; the polyester powder coating material of low melting temperature is melted in advance by atmosphere heating; the fluoric powder coating material of a high melting temperature is subsequently melted while allowing the polyester powder coating material of a low melting temperature to pass through the voids in the coating material powder layer to form a base coating film in the lower layer; and a functionality exerting film for securing weatherability is formed so as to be loaded on a base coating. The functional coating where fluorine consumption is decreased may be obtained by making use of time-gap melting of coating material with both the hot blending and temperature raising of the coating object to dispose the fluoric coating on the surface without performing a uniform distribution in the coating. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for electrostatic coating of a functional coating film, and to a functional coating-forming building material for powder coating.

  As this kind of electrostatic coating method (which may be called electrostatic powder coating method), for example, a hot blend powder coating in which different coating film components are heated and kneaded, such as a polyester coating and a fluorine coating, is used. For example, a building material such as an aluminum sash having a functional coating film excellent in weather resistance formed by electrostatic coating is known.

  According to Patent Document 1, a hot blend powder coating material includes, for example, a fluorine-containing copolymer having a crosslinkable reactive group such as partially fluorinated polyester and a curing agent that crosslinks with the crosslinkable reactive group. A coating composition obtained by adding a pigment to this and melt-kneading it to a ratio of 98/2, and using this to electrostatically coat building materials such as aluminum sashes, thereby providing a powder coating with excellent weather resistance The functional coating film is formed on the building material.

International Publication WO01 / 025346

  In this case, it becomes possible to form a functional coating film that ensures good adhesion due to the polyester component and excellent weather resistance due to the fluorine component as a colored coating film on the building material. However, in the case of such a functional coating film of the coating composition, the coating film component exhibiting the functionality, Patent Document 1 tends to use a large amount of fluorine component for ensuring weather resistance. Invite people to increase costs.

  That is, when the coating composition is used, the coating film component according to the blending ratio of the coating composition is uniformly distributed in the coating film. Where a polyester component and a fluorine component always exist according to the blending ratio, in order to ensure weather resistance as a functional coating film, it is sufficient that the fluorine component is present on the surface layer of the coating film, and therefore If the coating film component exhibiting functionality is arranged on the surface layer and the arrangement of the coating film component exhibiting functionality in the film thickness direction part other than the surface layer can be omitted, the cost increase can be suppressed as much as possible. It becomes possible.

  The present invention has been made in view of such circumstances, and the problem to be solved is a coating film component that exhibits functionality on the surface layer and a coating film component that forms a coating film base on the lower layer as easily and reliably as possible. An electrostatic coating film forming architecture in which a functional coating film component is arranged on the surface layer and a coating film component forming the coating film base is arranged on the lower layer. In providing materials.

As a result of diligent examination along the above-mentioned problems, using different types of powder coatings on the low temperature side and the high temperature side, which have different heat melting temperatures (sometimes referred to as heat softening temperatures), Dry blending is carried out according to a desired blending ratio, and a paint powder layer is formed by electrostatically applying to the object to be coated, and then the paint powder layer is baked by heating the atmosphere of the object to be coated. Due to the time difference in the temperature rise of the object to be heated, the low temperature side powder coating in the coating powder layer is first thermally melted, and then the high temperature side powder coating is thermally melted. Dissimilar powder coatings are arranged at high density on the surface layer and the lower layer respectively so that the low temperature side powder coating flows to the lower layer by the time difference melting and the high temperature side powder coating is located on the surface layer. Density arrangement, upper layer in the lower layer, lower layer in the upper layer It can be assumed that the remaining membrane components, therefore, the low-temperature side of the coating and the membrane base, a dry blend of different powder coating with the hot side of the functional for exerting, powder coating by an object to be coated warm By utilizing the time difference melting of the coating film, it is possible to arrange the functional coating film component on the surface layer and the coating film component forming the coating film base layer on the lower layer without distributing it uniformly throughout the functional coating film. It came to the knowledge that it can be set as the functional coating film which demonstrates functionality easily and reliably, reducing the usage-amount of the powder coating material for display.

The present invention has been made on the basis of such knowledge. That is, the invention according to claim 1 is different from the low temperature side for coating film base and the high temperature side for functional display, wherein the heat melting temperature is high and low different temperature. Using powder coating, electrostatic coating is applied to the object to be coated and baking is performed by heating the atmosphere of the object to be coated. The functional coating film is characterized by forming a high-performance coating film with a high-temperature side powder coating on the surface layer and placing the surface coating layer on the lower layer and the lower layer coating component on the surface layer. This is an electropainting method.

  In addition to the above, the invention according to claim 2 is a polyester-based coating on which the low-temperature side is polyester-based so that a weather-resistant coating film is formed as a functional coating film for building materials used outdoors. 2. The electrostatic coating method for a functional coating film according to claim 1, wherein the high temperature side is a fluorine-based powder coating.

The invention according to claim 3 is to provide an electrostatic coating film-forming building material in which a functional film is formed at as low a cost as possible by arranging a film component exhibiting functionality on the surface layer. In addition, electrostatic coating and coating of the object using different types of dry blend powder coating on the low temperature side for the coating film base and the high temperature side for exhibiting functionality , with the heat melting temperature being a high and low different temperature. It comprises a functional coating film formed by baking by heating in an atmosphere, and the functional coating film is disposed in high density with the surface coating layer remaining on the lower layer and the lower layer coating component remaining on the surface layer. It is a functional coating-forming building material for powder coating.

  The present invention uses each of these as the gist of the invention as means for solving the above problems.

  Since the present invention is configured as described above, the invention according to claim 1 is a dry blend of different types of powder paints for a low-temperature-side coating base and a high-temperature-side functional display, By utilizing the time difference melting of powder coatings by increasing the temperature, a coating component that exhibits functionality is placed on the surface layer and the coating layer component that forms the coating base is placed on the lower layer without being evenly distributed throughout the functional coating layer. By doing so, it is possible to provide an electrostatic coating method for a functional coating film that easily and reliably exhibits functionality while reducing the amount of the powder coating used for exhibiting functionality.

  In addition to the above, the invention described in claim 2 can form a coating film that ensures weather resistance as a functional coating film for building materials used outdoors.

  Invention of Claim 3 provides the coating-film-forming building material of the electrostatic coating which formed the functional coating film as low-cost as possible by arrange | positioning the coating-film component which exhibits functionality on the surface layer. Can do.

It is the graph and conceptual diagram which show the relationship between atmospheric heating and the change of dry blend powder coating material. It is a photograph of the coating powder layer surface. It is a photograph of the coating-film surface which baked the coating-material powder layer of FIG. It is a graph which shows the color tone change result after the accelerated weathering test by a metal weather tester. It is a graph which shows the gloss retention result after the accelerated weather resistance test by a metal weather testing machine. It is a graph which shows the color change result after the accelerated weather resistance test by a sunshine weather tester. It is a graph which shows the gloss retention result after the accelerated weather resistance test by a sunshine weather tester.

The electrostatic coating method of the present invention will be described in more detail below. The electrostatic coating method of the present invention is a different type of dry blend powder coating on the low temperature side for the coating base and the high temperature side for exhibiting functionality. Applying electrostatic coating to the object to be coated and baking by heating the atmosphere of the object to be coated. It forms a high performance side coating film with a high temperature side powder coating and arranges the coating component of the lower layer on the lower layer and the lower layer on the surface layer with high density arrangement. It undergoes a dry blending process for dry blending body paint, an electrostatic coating process for simultaneously applying different types of powder paints dry-blended to the object to be coated, and a heating process for heating the object to the atmosphere. As a thing, and this A functional coating-forming product for powder coating that has a base coating with a warm-side powder coating and a powder coating with a high-density arrangement of functional coatings with a high-temperature powder coating on the surface. It can be obtained easily and reliably.

  The functional coating film can ensure, for example, weather resistance, contamination resistance, etc., and the low temperature side powder coating material for the coating film base and the high temperature side powder coating material for the functional application are made of known coating materials. It can be used in combination, but the low temperature side is made of polyester, and the high temperature side is made of a fluorine-based powder coating. For example, various building materials such as aluminum sashes, curtain walls, gates, etc. A favorable functional coating film suitable for outdoor use can be formed while ensuring good adhesion with the polyester powder coating and high weather resistance with the fluorine powder coating on the high temperature side.

  When the dry-blended dissimilar powder coating is electrostatically applied to the object to be coated, and the object is heated to the atmosphere, the base coating with the low-temperature side powder coating is applied to the lower layer due to the difference in the temperature of the object to be heated in the atmosphere heating. The film can be arranged in high density on the surface layer with a high performance side powder coating.

  The mechanism is not always clear, but in the powder layer of different types of powder paint before baking, which is electrostatically applied to the object, the low-temperature and high-temperature powder paints are present in the dry blend ratio. However, since the coating particles of the powder coating have an indefinite shape, the coating is performed with a space between the powder coatings, and thus the coating powder layer. Is recognized as having a layer considerably thicker than the coating thickness after baking, and the temperature of the coating is increased by heating the atmosphere of the coating, and the low-temperature powder coating is melted by heat. When the temperature is reached, the base is such that the powder coating on the low temperature side is first thermally melted, passes through the voids in the coating powder layer, flows to the object side, that is, the lower layer, and collects in the lower layer. While the lower layer part forming the coating film is formed, the hot melting temperature of the powder coating on the high temperature side is reached , The hot side of the powder coating is subsequently thermally melted, apparently to form a surface layer portion forming the feature exhibited coating as is placed on the upper surface of the lower layer portion.

  According to the experimental results, the base coating film and the function-demonstrating coating film are mostly composed of the coating components of the low-temperature side and the high-temperature side powder coating, respectively. In view of this point, it is recognized that the coating component due to low-temperature powder coating is somewhat mixed with the functional coating film. In the functional coating formed by baking, the lower layer and the surface layer are not laminated with a clear boundary. The coating components of the powder coating are arranged at high density, respectively, while the surface coating is formed in the lower layer, and the coating coating component of the other layer in the lower layer is left in the surface layer to form a functional coating film. be able to.

  Then, the relationship between the base coating film and the functional coating film is that the powder coating on the low-temperature side, which has been softened and melted in advance, sews through the voids in the coating powder layer and collects in the lower layer. The powder coating on the high temperature side is taken in by fluidization of the powder coating on the low temperature side and remains so as to be mixed in the base coating film, while the powder coating on the low temperature side The coating component of the low temperature side powder coating cannot pass through the void-free portion where the powder coating on the high temperature side collapses due to the flow of the powder, and the low temperature side powder coating remains in the functional coating film. Seems to do. In addition, the coating film component by the low temperature side powder coating collects in the lower layer, for example, in the voids formed in the coating powder layer in addition to the self-weight of the coating film component due to the suspended support of the object to be coated It is recognized that the air pressure is reduced as a result of the temperature rise of the object to be coated, so that the pressure in the gap is reduced.

  On the other hand, regarding the SP value of polyester and fluorine (difference in solubility parameter), it is assumed that when ΔSP> 1, it is easier to separate and the smaller SP value is easier to coordinate to the gas phase side (surface layer side). However, for example, since the SP value of the low-temperature polyester-based paint in the powder paint used in the following examples is 10.7 and the SP value of the fluorine paint is 8 to 9, ΔSP is 1.7 to 2.7. And the SP value is ΔSP> 1. Therefore, from the SP value, it is recognized that the fluorine powder is arranged on the surface layer during the melt heating.

  Using polyester powder paint as the base paint on the low temperature side and fluorine powder paint as the high performance function paint, changing the blend ratio of the dry blend, and electrostatic coating of the aluminum extruded material to the object to be coated FIG. 1 shows the relationship between the temperature change from room temperature of 25 ° C. to 190 ° C. for about 5 minutes and the change of each powder coating material when the coating object is heated.

  When the temperature of the article to be coated is gradually raised by heating in the atmosphere, the polyester powder coating melts and forms a fusion around 80 ° C, while the fluorine powder coating melts around 150 ° C. During the interval, the concentration of the base coating film on the lower layer portion of the low-temperature side polyester powder coating and the subsequent surface coating of the functional coating film on the high-temperature side fluorine powder coating are performed.

  Similarly, using polyester powder paint as the base paint on the low temperature side and fluorine powder paint as the high performance function paint, changing the blending ratio of the dry blend, electrostatic coating on the aluminum extruded material The coating is heated and the coating is heated to form a functional coating (coat thickness 42 μm) on the coating, and the surface layer of the functional coating is measured by infrared spectroscopy to obtain a fluororesin / polyester. The peak height ratio of the resin (1700/1720 cm −1) was determined, a calibration curve was created based on the fluorine resin ratios of 0% and 100%, and the fluorine ratio was calculated twice. Table 1 shows the results.

  According to Table 1, in the surface layer having a depth of 0.5 μm from the surface of the functional coating film, when polyester (P): fluorine (F) = 0: 10, P: F = 10: 0, fluorine is 100% and 0%, when P: F = 5: 5, fluorine is 93% (average value), when P: F = 7: 3, 87%, when P: F = 8: 2, 76 %, When P: F = 3: 7, it is 95%, and when P: F = 5: 5, the surface is 11 to 19 μm and fluorine is 68% and 95% (actual measured value), 34 to 42 μm. It was 64% and 98% (same). Regardless of the blending ratio, a functional coating formed by dry blending polyester and fluorine, where fluorine is disposed on the surface, in other words, polyester is disposed in the lower layer, functional coating Since the coating layer component of the other type is detected on the surface layer and the lower layer, the remaining coating layer component of the other type is left, and the arrangement of the surface layer and the lower layer is not laminated but has a high density distribution. It became clear that there was.

  On the other hand, polyester powder paint is used as the base paint on the low-temperature side, and fluorine powder paint is used as the high-performance function paint. However, the pigment is added, and the polyester powder paint is white and the fluorine powder paint is gray. Fig. 2 is a photograph of the coating powder layer surface that was colored and dry-blended at a blending ratio of P: F = 7: 3, then electrostatically applied to the object to be coated (gun distance 30 cm) and observed with a microscope. Furthermore, the atmosphere heating (180 degreeC, 20 minutes) of a to-be-coated object is performed, a functional coating film is formed, and the photograph of the coating-film surface similarly observed and photographed with the microscope is shown in FIG.

  FIG. 2 shows a surface state in which many white colors are obtained by uniform blending with P: F = 7: 3 by dry blending, and there are few gray colors. However, in FIG. This shows a reduced surface state, and it has been clarified that fluorine is arranged at a high density on the surface layer by the functional coating film.

  In the present invention, it is preferable to use various metals such as an aluminum extruded profile, an aluminum plate, and a steel plate as an object to form a functional coating film that ensures weather resistance and contamination resistance.

  Electrostatic coating of objects to be coated is carried out in the usual way, such as using a hanger on the conveyor rail to coat the objects through the spray booth and baking booth, electrostatic coating at the spray booth, and atmospheric heating at the baking booth. In this case, the electrostatic coating may be carried out in accordance with conventional methods of electrostatic coating, including the gun distance, needle voltage, coating amount, etc. There is no need to set.

  The dry blending of the different types of powder paints may be performed at a predetermined mixing ratio on site before supplying the powder paint to the spray booth, or may be performed in advance at a dedicated factory. The spray booth overspray paint is preferably recovered and reused to eliminate paint loss.

  The atmosphere heating of the coating is performed so that the temperature of the coating is increased from the temperature below the heat melting temperature of the powder coating on the low temperature side for coating base to the temperature on the high temperature side showing the functionality. However, when the polyester and fluorine powder coating is used, the ambient temperature may be set from room temperature to about 200 ° C.

  For example, the object to be coated with electrostatic coating is a functional coating film that has weather resistance of fluorine that greatly exceeds the weather resistance of polyester, for example, window opening members such as aluminum sashes, curtain walls, etc. If it is widely used for various building materials installed outdoors such as wall materials, balconies, gates, etc., it will prevent the deterioration of the coating film as much as possible and provide the best possible surface condition over a long period of time. Can be maintained.

  Furthermore, including the formation of a colored functional coating film by adding pigments, etc., in implementing the present invention, the low temperature side powder coating material for coating film base, the high temperature side powder coating material for exhibiting functionality, the coating Specific forms, methods, conditions, types, etc. of materials, dry blending of powder coating, electrostatic coating, atmosphere heating, polyester powder coating, fluorine powder coating, building materials, etc. Various forms can be employed without departing from the gist of the invention.

  6 × 17 cm JIS6063-T5 plate material is colored the same color of gray with a common pigment, polyester powder paint as a low temperature side base paint, fluorine powder paint as a high temperature side functional paint, polyester powder After dry blending at the blending ratio of Paint 7 and Fluorine Powder Paint 3 and electrostatically coating, the sample is heated in an atmosphere from room temperature to 180 ° C and subjected to accelerated weathering test using a metal weather tester and sunshine weather tester Were taken out every 120 hours in the former and every 500 hours in the latter, and color change and gloss retention were measured with a color difference meter and gloss meter, respectively. 4 and 5 show the results of the accelerated weather resistance test using the metal weather tester, and FIGS. 6 and 7 show the results of the accelerated weather resistance test using the sunshine weather tester.

  The blending ratio of the dry blend was the same as in Example 1 except that the polyester powder paint 5 and the fluorine powder paint 5 were used. Similarly, the results are shown in FIGS. 4 and 5 and FIGS.

  The blending ratio of the dry blend was the same as in Example 1 except that the polyester powder paint 3 and the fluorine powder paint 7 were used. Similarly, the results are shown in FIGS. 4 and 5 and FIGS.

Comparative Example 1

  The powder coating material was the same as that of Example 1 except that the fluorine powder coating material was not used and only the polyester powder coating material colored in gray with a pigment was electrostatically applied. Similarly, the results are shown in FIGS. 4 and 5 and FIGS.

Comparative Example 2

  The powder coating material was the same as Example 1 except that the polyester powder coating material was not used and only the fluorine powder coating material colored in gray with a pigment was electrostatically applied. Similarly, the results are shown in FIGS. 4 and 5 and FIGS.

  The color difference change by the metal weather tester in FIG. 4 is only for the polyester powder paint sample of Comparative Example 1, and ΔE = 1.5 when 300 hours have elapsed after the start of the test, and ΔE = 7. In contrast, the samples obtained by dry blending the polyester powder coating materials and the fluorine powder coating materials of Examples 1 to 3 all had ΔE = 1.0 or less after 500 hours, and Comparative Example 2 It was almost the same as the sample of only the fluorine powder coating.

  Similarly, the gloss retention by the metal weather tester of FIG. 5 is about 85% at the time of 360 hours after the start of the test and slightly higher than 20% at the time of 500 hours for the sample of the polyester powder paint of Comparative Example 1 only. On the other hand, the samples obtained by dry blending the polyester powder coatings of Examples 1 to 3 and the fluorine powder coating were all about 85% after 480 hours, and the fluorine powder of Comparative Example 2 It was only slightly lower than the paint-only sample.

  The change in color difference by the sunshine weather tester in FIG. 6 is not much different when 1500 hours have elapsed since the start of the test, and all of them fall within ΔE = 1.0 or less, but in the sample of only the polyester powder paint of Comparative Example 1. Is about ΔE = 1.25 after 2000 hours from the start of the test and ΔE = 1.5 after 2500 hours, whereas the polyester powder coating and the fluorine powder coating of Examples 1 to 3 The dry blended samples had ΔE = 1.0 or less at the time point of 2000 hours and 2500 hours, which was slightly higher than the sample of the comparative example 2 containing only the fluorine powder coating.

  Similarly, the gloss retention rate by the sunshine weather tester in FIG. 7 is not much different in the sample of only the polyester powder paint of Comparative Example 1 as it is slightly less than 100% after 1000 hours from the start of the test. The polyester powder coating materials and fluorine powders of Examples 1 to 3 were about 75% at 1500 hours after the start of the test, about 45% after 2000 hours, and several% after 2500 hours. All of the samples obtained by dry blending the paint were about 90% at the time point of 2500 hours, which was slightly lower than the sample of the fluorine powder paint of Comparative Example 2 alone.

  From the above, the dry blended polyester powder coating of different paints forms a base coating and the fluorine powder coating forms a surface coating, thereby exhibiting high weather resistance, and the dry blend formulations of Examples 1 to 3 It was found that the weather resistance did not vary greatly depending on the ratio.

Claims (3)

Using different dry blend powder coatings on the low temperature side for the coating film base and the high temperature side for functioning with different heat melting temperatures, and electrostatic coating on the coating and baking by heating the coating. The base coating with the low-temperature side powder coating is formed in the lower layer due to the temperature rise time difference of the coated object in the atmosphere heating, and the functional coating film with the high-temperature side powder coating is formed on the surface layer, and the surface layer on the surface layer is formed on the lower layer. An electrostatic coating method for a functional coating film, characterized in that the coating film components of the lower layer remain and are arranged in high density.   2. The method of electrostatic coating of a functional coating film according to claim 1, wherein the low temperature side is a polyester-based powder coating and the high temperature side is a fluorine-based powder coating. Using different dry blend powder coatings on the low temperature side for the coating film base and the high temperature side for functioning with different heat melting temperatures, and electrostatic coating on the coating and baking by heating the coating. A powder coating characterized by comprising a functional coating film formed by applying a surface coating on the lower layer of the functional coating film and a lower layer coating film component remaining on the surface layer, respectively. Functional film forming building material.