JP2006016454A - Powder coating for satin coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder coating realizing a uniform and dense satin pattern, giving comfortable touch and suppressed gloss by the dull surface obtained by the satin coating film and, accordingly, having high designing flexibility on the coated surface. <P>SOLUTION: The powder coating containing silica beads 3 insoluble in a molten resin component 2 and having a surface energy higher than the surface tension of the resin component 2 has an average particle diameter range of 5-20μm in the whole powder coating and the maximum particle diameter of <36μm. The silica bead 3 has an average particle diameter range of ≤20μm and the amount of the bead is 5-30 wt.% based on the total powder coating. A coating film having improved designing flexibility can be produced by using the resin component 2 composed of a high melt-viscosity resin having a melt viscosity of ≥8 dPas at 150°C or a high melt-viscosity and high reaction rate resin having a melt viscosity of ≥8 dPas at 150°C and a gel time of ≤180 sec at the temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a powder coating material for forming a satin-like concavo-convex pattern coating film referred to as a “pear texture” pattern.

  In recent years, with the progress of application development of powder coatings, a wide variety of powder coatings for forming concavo-convex pattern coating films having excellent design properties have been provided. Examples of such coating film types include concavo-convex pattern coating films such as matte tone, velvet tone, suede tone, and hammer tone finish. In forming such a concavo-convex coating film, for example, the one shown in Patent Document 1 uses a dry blend of two types of resins for thermosetting powder coatings having different curing reactivity as a powder coating material. A concavo-convex pattern is obtained by utilizing the difference in curing reaction and the difference in melt viscosity during heat melting. That is, when the powder coating material of Patent Document 1 is heated and melted and cured, the curing reaction of the first resin proceeds faster, while the second resin containing cellulose ester has a melt viscosity higher than that of the first resin. Small and slow curing rate. Therefore, in this state, when the first resin contracts as it hardens, the second resin having a low melt viscosity is pulled. Then, when the second resin is subsequently cured, the second resin portion is recessed, and as a result, an uneven pattern is formed.

  By the way, the powder coating material for a satin coating film called a satin-like uneven pattern is required to be formed more uniformly and densely among the above-described uneven pattern types. However, when the technique shown in Patent Document 1 is used, mixing of both resins tends to be non-uniform during dry blending of both resins, and it is difficult to accurately reproduce the formation of uneven patterns. For this reason, the obtained coating film often has pear texture unevenness and lacks practicality.

On the other hand, the one shown in Patent Document 2 specializes the target product as a satin coating, and has a stable shape even when the coating component is heat-cured with respect to the main component thermosetting powder coating component. Add resin beads that can keep In this method, by forming the coating film with a film thickness that does not exceed the average particle diameter of the resin beads, the resin beads protrude as a large number of protrusions on the coating film surface, and a satin-like unevenness (pear texture) pattern is obtained. .
JP-A-5-78605 (page 5-6) JP-A-9-302272 (4th page, FIG. 1)

  However, in the case of the one shown in Patent Document 2, it is necessary to control the coating film thickness so as not to exceed this particle size according to the particle size of the additive resin beads, and the difficulty in the actual process is high. For example, the actual coating film thickness necessarily includes non-uniform variations, and it is necessary to consider it as a parameter factor that inhibits the uniformity and fineness required by the satin pattern. In addition, as the “average roughness” index, which specifically expresses the uniformity and fineness of the textured pattern irregularities, it is usual to employ both the centerline average roughness (Ra) and the ten-point average roughness (Rz). It is. The center line average roughness (Ra) is an index of the density of the concavo-convex pattern, while the ten-point average roughness (Rz) is an index of the height of the concavo-convex pattern. . For this reason, in order to obtain good measurement values in both indicators, it is necessary to form a coating film with the additive resin bead particle size at each measurement point and the coating film thickness corresponding to this, which is considered. The power parameter factor further increases. As a result, the dimensional accuracy of the satin pattern obtained in the actual painting process is lowered, and such a problem becomes more prominent particularly as the painting target surface becomes more complicated.

  In view of the above problems, the present invention realizes a uniform and dense satin pattern, and the roundness of the surface obtained in association with this provides a highly sensitive tactile sensation and a suppressed gloss, An object of the present invention is to provide a powder coating that can have high designability on the painted surface.

  In order to solve the above-mentioned problems, the powder coating material for satin coating of the present invention comprises a resin component and a powdery material that is insoluble in the molten resin component. The surface energy value of the resin component is larger than the surface tension value of the resin component, and the particle diameter specification is set such that the average particle diameter range of the entire powder coating is 5 to 20 μm and the maximum particle diameter is less than 36 μm. It was. In addition, 5 to 15 μm as the average particle size range and less than 25 μm as the maximum particle size are more preferable setting ranges of the particle size specification.

  According to this, when the powdery material and the resin component are compared, when the surface energy of the powdery material has a relatively large energy value than the surface tension of the resin component, the solid surface of the powdery material, Since the molten resin component is attracted and spreads, the surface of the coating film protrudes while being covered with a thick resin component as a main component, and as a result, the flat portion of the surface is reduced. A good satin-patterned coating film surface is obtained even in the centerline average roughness (Ra) indicating the density of the uneven pattern on the surface.

  In the opposite case, that is, when the surface energy of the powdery substance has an energy value relatively smaller than the surface tension of the resin component, the insoluble powdery substance and the resin component as the main component are not compatible, Therefore, the insoluble powdery substance is exposed from the coating film without being coated on the resin component. As a result, a flat surface shape is maintained on the surface of the coating film without forming an uneven surface optimal for the satin pattern. With such a flat surface shape, only an unsatisfactory appearance with conspicuous gloss can be obtained.

  The insoluble powdery substance described above constitutes the convex part of the viscous satin pattern. And the setting of the particle diameter in the whole powder coating material when this powdery substance is contained shall be 5-20 micrometers as an average particle diameter range, and less than 36 micrometers as a maximum particle diameter. By aligning the particle diameter within these ranges, the coating surface charge by electrostatic spray becomes substantially constant, and the adhered coating material is distributed in a close-to-fine state on the coating film surface. As a result, a uniform coating film is formed. In addition, 5 to 15 μm as the average particle size range and less than 25 μm as the maximum particle size are more preferable setting ranges of the particle size specification.

  The resin component as the main component may be a resin that is usually used as a powder coating. In the present invention, the resin component has a high melt viscosity at 150 ° C. of 8 dPa · s or higher. In addition to the high melt viscosity characteristics, a resin having high-speed reactivity with a gel time of 180 seconds or less at the same temperature (150 ° C.) is used. By using such a high melt viscosity resin, or a resin having a high melt viscosity and a high reactivity, a better satin pattern can be obtained on the surface of the coating film.

  Among the high melt viscosity and high-speed reactivity that are the characteristics of the present invention, regarding the use of a high melt viscosity resin, the resin component itself flows unnecessarily due to the high viscosity exhibited by the resin component as the main component in the molten state. There is an advantage that it is prevented. That is, when a powder coating is heated and melted, a coating film is formed with a resin component as a main component. At that time, if a high melt viscosity resin of 8 dPa · s or more (150 ° C.) is used, the coating film forming surface is leveled. Thus, a good satin-patterned coating film surface can be obtained even with a ten-point average roughness (Rz) indicating the height of the uneven pattern on the surface.

  Furthermore, by using a high melt viscosity resin, a flattened coating film with uniform particle adhesion and a satin pattern coating film surface using the same can be obtained even in complicated shape surfaces such as corners and walls. There is also an advantage.

  Furthermore, in addition to high melt viscosity characteristics, high-speed reaction characteristics, that is, by using a high-speed reactive resin with a gel time at 150 ° C. of 180 seconds or less, the quick reactivity provided by the resin component as the main component has a high viscosity at the time of melting. In combination with this, the leveling property of the coating film forming surface can be further suppressed, and a coating film surface having a better ten-point average roughness (Rz) can be obtained.

  As described above, according to the present invention, good results can be obtained for both the ten-point average roughness (Rz) and the centerline average roughness (Ra) without incorporating a highly difficult method such as film thickness control. It is done. And the coating-film surface formed with this powder coating material forms a uniform and precise | texture finish pattern. Moreover, the roundness of the surface obtained in connection with this provides a highly sensitive tactile sensation and suppressed gloss, and as a result, a painted surface with a high design property is obtained.

Furthermore, in the present invention, the insoluble powdery substance added to the powder coating material is further insoluble in the resin component even at the coating curing temperature. The resin component is finally heat-cured through heating and melting, but it is important to maintain insolubility with respect to the resin component throughout this process. By maintaining a stable shape while being insoluble, the satin pattern is surely formed on the coating surface. Further, as an example of the insoluble powdery substance, silica beads are optimal, but besides silica beads, metal iron or metal iron oxide such as FeO, Fe ₂ O ₃ , Fe, titanium oxide, aluminum oxide, Inorganic material beads made of at least one of inorganic materials such as zirconium oxide, zinc oxide, calcium carbonate, yellow lead, magnesium oxide compounds such as talc, and barium sulfate can be used.

  The insoluble powdery substance typified by silica beads preferably has an average particle size range of 20 μm or less, and is contained in an amount of 5 to 30% by weight based on the whole powder coating material. . In addition, the case where it is 8-12 micrometers as an average particle diameter range and the addition amount with respect to the whole powder coating material is 10-15 weight% can be made into a more preferable setting range.

  Unlike single component inorganic material beads with only one kind of inorganic material, mixed component inorganic material beads with multiple types of inorganic materials have different material types and particle sizes as the material components are mixed. become. However, as long as the above-mentioned conditions regarding the kind of inorganic material and the particle diameter are satisfied, the mixed component inorganic material beads can obtain a satin pattern that is similar to or more dense than the single component inorganic material beads.

  The powder coating for satin coating of the present invention is composed of a resin component and a powdery substance, and among these, the powdery substance is insoluble in the resin component that has been melted by heating and is in a molten state. Since the components are drawn while being drawn, a good satin-patterned coating film surface can be obtained. Furthermore, the leveling property of a coating-film formation surface can be suppressed by using high melt viscosity resin or high melt viscosity and high-speed reactive resin. In addition, a good satin-patterned coating film surface can be obtained even on complicated shapes such as corners and walls.

  As described above, according to the present invention, without incorporating a highly difficult method such as film thickness control, the ten-point average roughness (Rz) and the centerline average roughness (Ra) are excellent in both uniform and precise indexes. Nashinashi pattern is formed. Then, due to the roundness of the surface obtained along with this, a highly sensitive tactile sensation and a suppressed gloss are obtained, and as a result, a painted surface with a high design property is obtained.

  FIG. 1A shows an initial state when the powder coating material for satin coating of the present invention is applied to the surface 1 to be coated. The powder coating material is constituted by containing 10% by weight of silica beads 3 which are insoluble powdery substances having a surface energy value of 100 dyne / cm with respect to the resin component 2 which is a main component having a surface tension value of 45 dyne / cm. The And in the whole powder coating material, the range of the average particle diameter is 5-15 micrometers, and the maximum particle diameter is set to the range which is less than 20 micrometers. At this time, since the surface energy value of the insoluble powdery substance 3 is larger than the surface tension value of the resin component, the powdery substance 3 is well adapted to the resin component 2. For this reason, the insoluble powdery substance 3 protrudes while being thickly covered with the resin component 2 as the main component on the surface of the coating film, and as a result, the flat portion of the coating film surface is reduced. Furthermore, the melt viscosity of the resin component 2 is 8 dPa · s at 150 ° C., and when the resin component 2 becomes a high-viscosity molten state by heat melting with respect to the high melt viscosity resin component 2, Be the basis. That is, a coating film surface in which leveling properties are suppressed is formed by the high-viscosity molten resin 2, and is cured before leveling.

  Therefore, when this coating film surface is measured, the measurement result of the ten-point average roughness Rz, which is the height index of the formation surface, becomes good. And as shown in FIG.1 (b), the powder containing the resin component 2 which is a main component, and the additive silica bead 3 using high melt viscosity resin or resin with high melt viscosity and high-speed reactivity In the paint, the heat-melted resin component 2 is drawn to the surface of the silica beads 3 and spreads. For this reason, the silica beads 3 are projected on the surface of the coating film with the resin component 2 being thickly covered, and a satin-like uneven pattern coating film is formed. Since the satin pattern obtained at this time is formed on the basis of a coating surface represented by a good ten-point average roughness Rz, a large number of additive silica beads 3 reliably protrude from the coating surface. As a result, a good measurement result can be obtained even in the centerline average roughness Ra indicating the density of the uneven pattern.

  Furthermore, as the resin component 2, a high melt viscosity resin having a melt viscosity at 150 ° C. of 8 dPa · s or higher, or a melt viscosity at 150 ° C. of 8 dPa · s or higher and a gel time at that temperature of 180 seconds or less. When a resin having a melt viscosity and a high-speed reactivity is used, the leveling suppression effect of the resin component at the time of heating and melting is increased, and both the ten-point average roughness (Rz) and the center line average roughness (Ra) are better. Results are obtained.

  In addition, a general thermosetting resin can be used for the high melt viscosity or high viscosity and high-speed reactive resin 2 used in the present invention. Examples thereof are thermosetting resins such as epoxy resins, polyester resins, urethane resins and acrylic resins. These may be used singly or may be obtained by blending a curing agent with a resin that melts or flows by heating.

  As an example of blending such a curing agent, some of thermosetting resins that can be used are exemplified. As an epoxy resin, for example, a glycidyl ether type epoxy resin of bisphenol and a dicyandiamide or an acid anhydride as a curing agent are used. The thing which mixed the thing can be mentioned.

  Moreover, as what combined the epoxy resin and the polyester-type resin, what mixed the glycidyl ether type epoxy resin of bisphenol and the polyester resin containing a carboxyl group as a hardening | curing agent can be mentioned.

  Examples of the urethane resin include a polyester resin containing a hydroxyl group and a mixture of glycidyl isocyanate as a curing agent.

  Moreover, as a polyester-type resin, what mixed the glycidyl isocyanate as a polyester resin containing a carboxyl group and a hardening | curing agent can be mentioned.

  Moreover, as what combined polyester resin and acrylic resin, what mixed the polyester resin containing a hydroxyl group and a carboxyl group, and the acrylic resin containing a glycidyl group as a hardening | curing agent is mentioned.

  Moreover, as acrylic resin, what mixed the acrylic resin containing a glycidyl group and a dibasic acid as a hardening | curing agent can be raised. In addition to the thermosetting resin, an ultraviolet curable resin that is cured by ultraviolet irradiation by adding a sensitizer to a monomer or oligomer such as an acrylic acid compound or an epoxy compound may be used.

  Furthermore, in addition to the examples of the contents of the high melt viscosity resin 2 or the high melt viscosity and fast reactive resin 2 and the additive silica beads 3, conventionally known additives such as curing catalysts may be used as necessary. Or curing accelerators, antioxidants, fillers, UV stabilizers, UV absorbers, heat stabilizers, anti-waxing agents, plasticizers, pigment dispersants, fluidity modifiers, slidability improvers, charge control agents, etc. Can be added.

  Alternatively, known external additives for inorganic fine particles having a fine particle diameter of 1 μm or less, such as aluminum oxide, silicon oxide, titanium oxide, and zinc oxide can be added in order to improve the fluidity and charging characteristics of the fine particle paint. . The addition amount is not particularly limited, but about 0.1 to 3.0 parts by weight of the external additive can be used with respect to 100 parts by weight of the powder coating material, and can be increased or decreased as necessary.

  Further, when a pigment is added to the powder coating for coloring, examples of the pigment to be used include titanium in white and carbon black in black. For gray, these pigments are mixed and used. Examples of cyan include organic and inorganic pigments such as cobalt blue, Prussian blue, phthalocyanine, and vat. Examples of yellow include organic and inorganic pigments such as quinaphthalone, azo, yellow iron oxide, ocher, yellow lead, sub-yellow lead, and cadmium yellow. Examples of magenta include quinacridone, anthraquinone, bengara, cadmium red, red lead, mercury cadmium sulfide, manganese purple, red-yellow chrome, molybdenum orange, azo, and thioindigo.

  The addition amount of the pigment is preferably about 0.01 to 5 parts by weight with respect to 100 parts by weight of the high melt viscosity resin in the case of an organic pigment, and 1 to 35 parts by weight with respect to 100 parts by weight of the high melt viscosity resin in the case of an inorganic pigment. The degree is preferred. Organic pigments and inorganic pigments can be used in combination.

  Examples of methods for producing powder coatings containing these components include high-melting viscosity resins or high-viscosity high-speed reactive resins, insoluble powdery substances, additives, and pigments as raw materials in ball mills, Henschen mixers, super mixers, etc. The mixture is melted and kneaded with a kneader such as a hot roll, an excluder or a kneader, and the resulting mixture is formed into pellets. Next, the obtained pellets are roughly pulverized by a pulverizer such as an atomizer, and pulverized by a pulverizer such as a jet mill under the conditions in consideration of the yield of the desired particle diameter. A powder coating material is obtained by classifying the obtained powder to a desired particle size by an air classifier such as an elbow jet or a fluid classifier such as a TSP separator.

  As another production method, the above components except for the insoluble powdery substance are produced by the same production method as described above, and the insoluble powdery substance is added to the produced powder coating material by a mixer such as a ball mill, a Henschen mixer, or a super mixer. By mixing, a powder coating is obtained.

  When applying powder paint, the powder paint is charged to a certain polarity by friction or corona discharge, and the powder paint is electrostatically attached to the surface of the grounded object. A method can be used in which the adhered powder coating layer is baked at about 120 to 250 ° C. for about 5 to 30 minutes and heated and melted to form a coating film. Alternatively, the powder coating is floated and fluidized in an air stream, and a pre-heated object to be coated is inserted into the air stream, and the powder paint adhering to the surface of the object to be coated is used for the heat of the object to be coated. Then, a method of melting and spreading can be used.

  In any of the coating methods, the leveling property of the coating film forming surface is suppressed by the high melt viscosity and high-speed reactive resin 2 in the molten state in the heating and melting and baking processes described above, and the heat resistance and solvent resistance are improved. The coating film is formed in a state where the provided silica beads 3 remain insoluble in the high melt viscosity resin 2. At that time, the silica beads 3 are fixed by the high melt viscosity resin 2 and are kept protruding from the coating surface. As a result, a satin pattern is formed. Thus, a uniform and dense satin pattern excellent in both the ten-point average roughness (Rz) and the centerline average roughness (Ra) is obtained without incorporating a highly difficult method such as film thickness control. It is formed. And the roundness of the surface obtained in connection with this forms a highly sensitive tactile sensation or a suppressed glossy satin pattern (see FIG. 1B).

  The satin pattern thus formed is excellent in coating film properties in terms of hardness, solvent resistance, abrasion resistance, and the like.

As an example of the insoluble powdery substance, silica beads 3 are optimal, but besides silica beads, metal iron or metal iron oxides such as FeO, Fe ₂ O ₃ and Fe, titanium oxide, and aluminum oxide Inorganic material beads made of any one of inorganic materials such as zirconium oxide, zinc oxide, calcium carbonate, yellow lead, magnesium oxide compounds such as talc, and barium sulfate can be used.

  In addition, the insoluble powdery substance typified by silica beads preferably has an average particle size range of 20 μm or less and is contained in an amount of 5 to 30% by weight based on the whole powder coating material. . At this time, if it is 5% or less, the unevenness of the coating film surface is insufficient and there is no texture, and if it is contained 30% or more, there are too many insoluble powdery substances relative to the resin component, and the coating film cannot be formed. End up. In addition, the case where it is 8-12 micrometers as an average particle diameter range and the addition amount with respect to the whole powder coating material is 10-15 weight% can be made into a more preferable setting range.

  In the case of mixed-component inorganic material beads using a plurality of types of inorganic materials, unlike the case of single-component inorganic material beads consisting of only one type of inorganic material, the material type and its particle size change as the material components are mixed. Will be different. However, by satisfying the above-mentioned conditions concerning the kind of inorganic material and the particle diameter, when using mixed-component inorganic material beads, a denser satin pattern can be formed more than single-component inorganic material beads.

Powder paint raw material by adding silica beads 3 having an average particle size of 10 μm to resin 2 having a high melt viscosity of 26 dPa · s at 150 ° C. and a gel time at that temperature of 90 to 180 seconds and high-speed reactivity It was created. This powder coating material has a silica bead 3 content of 14% by weight with respect to the whole, and an overall average particle diameter of 10 μm. The powder coating material was filled in a corona charging spray gun, and the coating was applied so that the film thickness was 25 to 30 μm. The setting conditions of the spray gun are a voltage of 30 to 40 KV, a current of 30 to 50 μA, and an air amount of 1.5 to 2 m ³ / h. After the completion of spray coating, the coating film was cured by heating at 170 ° C. for 20 minutes, and then the coating film appearance and surface roughness were evaluated. The results at this time are shown in FIG.

  FIG. 2 (a) shows an enlarged view of a satin pattern formed by exposing additive silica beads 3 to a resin film 2 having a high melt viscosity and a high-speed reactivity. As a result of visual observation, the obtained coating film 2 was in a state where a dense and uniform satin pattern was formed. Further, the surface roughness (ten-point average roughness (Rz) and centerline average roughness (Ra)) of the satin pattern and the undulation Sm of the coating film were confirmed, and each was numerically displayed in Table 1. As apparent from Table 1, the satin-finished coating film obtained by this example is fine and dense in ten-point average roughness (Rz) and centerline average roughness (Ra) (see FIG. 2 (b)). It can be seen that the interval between the irregularities (swells Sm) is very small.

  The coating is performed under the same coating conditions as in Example 1 except that silica beads 3 having an average particle size of 10 μm are used as the insoluble powdery substance and this is contained in an amount of 10% by weight based on the whole powder coating material. It was.

  The obtained coating film has the most uniform and dense satin pattern, and has a high tactile sensation and a suppressed gloss due to the roundness of the resulting surface.

  Coating is performed under the same coating conditions as in Example 1 except that silica beads 3 having an average particle size of 10 μm are used as the insoluble powdery substance and 15% by weight of silica beads 3 is contained in the whole powder coating material. It was.

  As a result of visual observation, the obtained coating film is in a state where a dense and uniform satin pattern is formed. As a result of measurement with a gloss meter from an angle of 60 degrees, a glossiness of 1.5% is obtained. It was found that a satin film with reduced gloss was formed.

  The coating was performed under the same coating conditions as in [Example 1] except that silica beads 3 having an average particle size of 20 μm were used as the insoluble powdery substance.

  As a result of visual observation, the obtained coating film was in a state where a dense and uniform satin pattern was formed. Compared with [Example 1], [Example 1] is slightly denser. Was over.

  The coating was performed under the same coating conditions as in [Example 1] except that the average particle size of the entire powder coating material was 20 μm.

  The obtained coating film is formed with a uniform and dense satin pattern, and also has a highly sensitive tactile feel and a suppressed gloss satin pattern due to the roundness of the surface obtained accordingly. However, when compared with that of [Example 1], the density of [Example 1] was slightly higher.

  The coating was performed under the same coating conditions as in Example 1 except that a high melt viscosity resin having a melt viscosity of 8 dPa · s at 150 ° C. was used as the resin component 2 as the main component. The obtained coating film had a uniform and dense satin pattern, and also formed a satin pattern with a high tactile sensation and a suppressed gloss due to the roundness of the surface obtained accordingly.

  [Example 1] except that a resin component 2 as a main component has a melt viscosity at 150 ° C. of 8 dPa · s and a high melt viscosity and high-speed reactive resin having a gel time of 90 to 180 seconds at that temperature. The coating was performed under the same coating conditions.

The obtained coating film has a uniform and dense pear texture pattern, and the roundness of the surface obtained along with this results in a highly sensitive tactile feel and suppressed gloss pear texture pattern. Was forming.
[Comparative Example 1]
The coating was performed under the same coating conditions as in [Example 1] except that two types of mixed paints having different curing reactivity were used instead of the mixture of the resin component and the additive silica beads. After heat-curing at 170 ° C., the coating film appearance and surface roughness were evaluated. The results at this time are shown in FIG.

  FIG.3 (b) expands and shows the coating material obtained by the mixed coating material from which curing reactivity differs. In the progress of the curing reaction, the first resin having a high curing rate is cured first (corresponding to the dark color portion). And before this part spreads on the to-be-coated surface 1, this part shrink | contracts, maintaining the area of an adhesion surface, and forms the projecting island 4. FIG. Thereafter, the second resin that is slowly cured is cured while spreading between the dark-colored islands 4. As a result, the film is cured and contracted in the thickness direction of the coating film, and the recess 5 is formed. As described above, due to the non-uniform mixing of the first and second resins, the surface of the coating film is formed with a non-uniform satin pattern composed of angulated protruding islands 4 and dents 5. The surface roughness (ten-point average roughness (Rz) and centerline average roughness (Ra) and swell Sm of the coating film) of the satin pattern at this time was confirmed, and each was numerically displayed in Table 1.

  As apparent from Table 1, the satin-patterned coating film obtained by this comparative example is non-uniform in both the ten-point average roughness (Rz) and the center line average roughness (Ra) (see FIG. 3B). It can be seen that the interval between the irregularities (swells Sm) is also very large. Further, in order to obtain a satin finish, it was necessary to apply a film thickness of about 50 to 70 μm.

[Comparative Example 2]
The coating was performed under the same coating conditions as in [Example 1] except that the average particle size of the entire powder coating material was 30 μm.

Although the coating surface obtained at this time is non-uniform, a satin finish is formed, but it is difficult to paint on parts having complicated shapes. This is because the powder coating material tends to accumulate in the concave portion of the complex shape surface, and the shape of the part cannot be reflected on the coating surface and reproduced.
[Comparative Example 3]
An insoluble powdery substance having a surface energy value of 40 dyne / cm is used, that is, a powdery substance smaller than the surface tension value (45 dyne / cm) of the resin component 2 is used, and the average particle diameter is 10 μm as the powdery substance. The coating was performed under the same coating conditions as in [Example 1] except that the above acrylic beads were used.

  The coating surface obtained with the compounded resin had many flat portions (leveled portions) and high glossiness (58%). As a result, the textured surface was insufficient.

  INDUSTRIAL APPLICABILITY The present invention can be used to form a coating film that clearly reflects the outline of a substrate and has a dimensional accuracy on parts having irregular shapes such as high-grade appearance products such as cameras, mobile phones, and various home appliances. .

(A) Schematic cross-sectional view showing the high melt viscosity resin and silica beads immediately after coating (b) Schematic cross-sectional view showing the coating surface formed after firing (A) Photograph showing the coating film surface obtained by [Example 1] (b) Graph showing the surface roughness of the coating film surface obtained by [Example 1] (A) Photograph showing the surface of the coating film obtained by [Comparative Example 1] (b) Graph showing the surface roughness of the coating film surface obtained by [Comparative Example 1]

Explanation of symbols

1 Coating target surface 2 Resin component (resin with high melt viscosity or high viscosity and fast reactivity)
3 Silica beads 4 First resin with high curing speed 5 Second resin with low curing speed

Claims (5)

A powder paint comprising a resin component and a powdery material insoluble in the molten resin component,
In the surface energy value of the powdery substance is larger than the surface tension value of the resin component,
An average particle size range of the entire powder coating material is 5 to 20 μm, and a maximum particle size is less than 36 μm. 2. The powder coating material for satin coating according to claim 1, wherein the resin component is a high melt viscosity resin having a melt viscosity at 150 ° C. of 8 dPa · s or more. 3. The powder coating material for satin coating according to claim 1, wherein the resin component is a high-speed reactive resin having a gel time at 150 ° C. of 180 seconds or less. The powdery substance is at least one inorganic material bead among silica, iron oxide compound, titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, yellow lead, magnesium oxide compound, and barium sulfate. The powder coating material for satin coating film according to any one of claims 1 to 3. 5. The powdery substance has an average particle size range of 20 μm or less, and is contained in an amount of 5 to 30% by weight based on the entire powder coating material. The powder coating material for satin coating film according to item 1.