JPS5819351B2 - ``Funtai Toriyouniyoruru Tasaishiyokumoyoushiagehouhou'' - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a multicolored pattern finish in one coat using a mixture of powder coatings having specific conditions.

Conventional paints for finishing multicolored patterns are composed of a colored liquid component that serves as a dispersion medium, and a dispersed phase that is a colored liquid component of two or more colors that do not dissolve in the dispersion medium. Or, it is made so that the granular dispersed phase remains dispersed and suspended.

However, this liquid multicolored pattern finishing paint is generally insufficient in terms of mechanical strength, heat resistance, corrosion resistance, etc. of the coating film, and the dispersion state of the dispersed phase becomes unstable when stored for a long time, resulting in the formation of patterns. It has drawbacks such as causing deterioration.

Therefore, there is a strong demand for the development of a method for finishing a multicolored pattern using a paint that has excellent coating performance, storage stability, etc., and that makes the painting process pollution-free.

As a result of research conducted in view of these circumstances, the inventor of the present invention has found that by using a mixture of powder coatings having specific conditions, a multicolored pattern coating film that satisfies the above requirements can be formed in one coat. He discovered a coating method and completed the present invention.

That is, the present invention has the following features: 1. A mixture of a powder coating for the lower layer and a powder coating for the upper layer consisting of a mixture of powder coatings of two or more colors is applied to the object to be coated, and the mixture is heated, melted, A method for applying a multi-colored pattern finishing powder paint by separating the powder paints, furthermore, (1) the mutual affinity parameter between each of the powder paint resins is a positive number, 0, or a negative number with an absolute value of less than 0.10. , ■ The surface tension of the powder coating resin for the lower layer is 0.5 dyne/cm or more greater than each resin in the powder coating for the upper layer, and the surface tension between each resin in the powder coating for the upper layer is The difference in surface tension is 5. Odyne /Cm or less; ■ The multilayer formation composite parameter of the powder coating resin for the lower layer is larger than each resin in the powder coating for the upper layer, and the ratio thereof is 1.5.
The above is desirable, and preferably the multi-layer forming composite parameter ratio between the resins in the powder coating for the upper layer is less than 1.5 to 0.
A method for finishing a multicolored pattern using a powder coating, characterized in that the color is 66 or higher.

2. A multicolored pattern finish obtained by applying a mixture of a powder coating for the upper layer and a powder coating for the lower layer consisting of a mixture of powder coatings of two or more colors to the object to be coated and heating and melting the mixture. A powder coating coating method, furthermore, (1) the affinity parameter between each of the powder coatings is a positive number, 0, or an absolute value of 0.
．． be a negative number less than 10; ■ the surface tension of each resin in the powder coating for the lower layer is 0 greater than that of the powder coating resin for the upper layer;
．． 5 dyne/crri or more, and the difference in surface tension between each resin in the powder coating for the lower layer is 5. Q
dyke /Cr1l or less; (i) the multilayer formation composite parameter of each resin in the powder coating for the lower layer is greater than that of the powder coating resin for the upper layer, and the ratio thereof is 1.5 or more; Preferably, the composite parameter ratio for multilayer formation between each resin in the powder coating for the lower layer is less than 1.5 to 0.
The present invention relates to a method for finishing a multicolored pattern using a powder coating, characterized in that the coating is 66 or more.

Powder coating for the upper layer in the present invention (hereinafter referred to as "upper layer paint")
Powder paint for the lower layer (hereinafter referred to as "lower layer paint") is a paint that is mainly located in the upper layer (gas phase side) of the formed coating film, and powder coating for the lower layer (hereinafter referred to as "lower layer paint") is the paint that is mainly located in the upper layer (gas phase side) of the formed coating film. It is a paint that is mainly placed on the painted surface side, and both of these are multilayered to form a multicolored patterned paint film.

The forms of the multicolored patterned coating films obtained by the present invention can be roughly divided into two types.

One of them is to form a multicolored pattern on the upper layer of the formed coating film by using a mixture of powder coatings of two colors or more than two colors having the above-mentioned specific conditions as the upper layer coating (hereinafter referred to as ``color pattern''). The other one is one in which a multicolored pattern is formed on the lower layer (hereinafter referred to as "second pattern coating J").

Which of these two forms to choose depends on the purpose, but for example, if emphasis is placed on adhesion to the object to be coated, corrosion resistance of the coating film, etc., the first pattern coating film is preferable; , a second pattern coating film is preferable when smoothness is important.

The affinity parameters used as indicators in the present invention are:
It is a numerical representation of the degree of affinity between the resins in each powder coating to be mixed, and when this parameter is a positive number, 0, or a negative number with an absolute value of less than 0.10, particularly preferably a positive number, The affinity between those resins is low,
Negative numbers whose absolute value exceeds 0.10, which are mutually incompatible or incompatible with each other, and when applied to the present invention, it is easy to make the coating film multilayered and form a multicolored pattern. If so, it is generally difficult to form a multilayer coating film because of their high affinity, and the object of the present invention cannot be achieved.

This affinity parameter is measured by observing the mixing state of both types of resins in a solution under certain test conditions, and the affinity parameter determined by this method is an essential element in the present invention. It is most preferable as an index regarding the degree of incompatibility or incompatibility between resins for powder coatings.

Specifically, toluene and methyl isobutyl ketone (MI
Using an equal volume mixture of BK) as a solvent, each of the test powder coating resins was made into a solution with a resin content of 33% by weight, and at 25°C, equal weights of the two resulting solutions were mixed. Mix.

After stirring the mixed liquid to make it sufficiently homogeneous, the liquid layer with a thickness of 5 crrL is seen with the naked eye under natural daylight, and if it is found to be completely transparent, it indicates the affinity of the combination of the two resins. The parameter is a negative number, and if turbidity is observed, it is a positive number.

To find the numerical value of this parameter, add ethylene glycol monomethyl ether acetate (CH
20CH2.CH20COCH3) is added dropwise to cause the turbidity to disappear due to the effect of a good solvent.On the other hand, in the case of 0 or a negative number, n-hexane is added dropwise to generate turbidity due to the destabilization of the solute due to dilution.

The numerical value of the affinity parameter P is calculated by the following formula.

Tazo A and B: Weight of each of the two resins in the mixed solution C: Weight of the solvent in the first mixed solution △D To the weight of either solvent added two drops: Correction coefficient, P is a negative number 1 when P is a positive number, 10 when P is a positive number
0/45 When P is a negative number and the amount of n-hexane dropped is extremely small and does not reach the minimum display unit, P is set to O.

If at least one of the two resins is insoluble in the mixed solvent, it is impossible to determine the affinity parameter by the above method, but the approximate numerical value can be indirectly determined by another method. You can know.

That is, in the case of an insoluble or poorly soluble resin such as polyethylene or polyamide, the straight lines of a sheet with a thickness of 400 to 500 μ obtained by molding the resin are placed on a glass surface in close contact with each other. The mixture is heated to a temperature at which both resins can be completely melted and held for about 30 minutes.

If the affinity parameter between both resins is a positive number, 0, or a negative number with an absolute value of less than 0.10, an interface or boundary layer is formed between both molten resins, resulting in discontinuity, but the absolute value In the case of a negative number of 0.10 or more, the composition changes continuously due to mutual diffusion, and no discernible interface is formed.

The presence or absence of such an interface can be easily observed with the naked eye by dispersing a colored pigment or dye such as carbon black into at least one of the two resins to create a color change. can.

The combination of powder coating resins used for the purpose of the present invention not only requires that the affinity parameter observed in the solution state be within the above range, but also that it is incompatible or incompatible even when the solvent is removed. Must be soluble.

That is, the mixed solution prepared when measuring the affinity parameter was applied to a transparent plate to obtain a dry film with a thickness of about 50 microns, and the solvent was evaporated to form a dry film, which was then exposed to transmitted light and scattered light. It is necessary to observe that turbidity or resin separation is observed.

If one or both of the two resins is insoluble in the mixed solvent, the formation of an interface, etc. in the sheet melting test described above indicates incompatibility between the two resins. Alternatively, it may be one that exhibits poor compatibility.

By specifying the affinity parameters between the mixed powder coating resins (three or more types) used in the present invention in this way, each resin becomes incompatible or poorly compatible, so that it can be mixed uniformly. This causes the formation of multiple layers between the lower layer and the upper layer and the formation of multicolored patterns.

In the present invention, the resin between the upper layer paint and the lower layer paint, which are mixed and used for the purpose of forming a multi-layered coating film in the upper layer and lower layer, has a difference in surface tension of the molten material. It is necessary to have

That is, the resin having low surface tension becomes all or a major part of the constituent components of the upper layer portion of the coating film when it is heated and melted.

In order to form a coating film with a clear multi-layer structure, the surface tension of the melted resin in the lower layer coating at the same temperature must be 0.5 dyne/more than that of the resin in the upper coating.
am or more, particularly preferably 2. It is necessary that it be larger than Odyne/cm.

If this difference in surface tension does not reach 0.5 dyne 7 cm, when a multilayer coating film is formed, the resin components may not be completely separated, especially in the upper layer of the coating film, resulting in irregularities. .

Therefore, in order to form the first pattern coating film, two
It is necessary to make the surface tension of the resin in the lower layer paint 0.5 dyne/cm or more higher than the surface tension of each resin in the powder paint (upper layer paint) consisting of a color or two or more colors. To form a two-pattern coating film, use two colors or two
The surface tension of each resin in the powder paint (lower layer paint) consisting of more than 1 color is 0.0% lower than that of the resin in the upper layer paint.
It is necessary to make it larger than 5 dyne/α.

In addition, the difference in surface tension between powder coating resins of each color in a powder coating of two colors or two or more colors (forming a multicolored pattern) is less than 5. Odyne /cyri, and this difference is 5. Odyne If it is larger than 7 cm, it will be difficult to form a clear multicolored pattern.

Furthermore, if the difference in surface tension between two colors or powder coatings made of two or more colors is 4 to 5 dyne/cIrL, the resin viscosities are high and similar, and the multilayer parameter values are also similar. It is desirable to form a clear multicolored pattern.

The temperature at which the surface tension is measured is the temperature immediately above the highest melting temperature of the respective component resins for each coating powder resin mixture, that is, the temperature at which the mixture is applied to the surface to be coated and melted. The most accurate method is to set the heating temperature to form a multilayer coating film, but in practice, in the case of any mixture, a constant temperature, for example 200°C, is used, and the value of surface tension at that temperature is used. , there is no problem and it is convenient to compare.

Surface tension of resin melt δL (dyne/Cm)
Although there are no particular restrictions on the method of measuring , for example, from the measured value of the contact angle θ between the melt and Teflon (tetrafluoroethylene resin),
n n ) and Sell's equation.

δS: Surface tension of Teflon (dyne/cm 2 ) In the present invention, an approximate value was obtained on the diagram by setting δS to 18.6 dyne/crfL.

The method for measuring the contact angle of a resin melt with respect to Teflon at a predetermined temperature, for example, 200°C, can be applied without any particular restrictions as long as it can determine the advancing contact angle.
For example, the resin to be measured is molded into a hemispherical shape with a diameter of approximately 2mvt, placed on a Teflon plate held horizontally with its spherical side facing down, and melted and cast in a constant temperature chamber maintained at a predetermined temperature. When equilibrium is reached, the sample is enlarged and projected or observed using a microscope.

If the melting temperature of the resin to be measured is high and it is not possible to directly calculate the surface tension at this temperature by measuring the contact angle with Teflon at a given temperature, it is possible to calculate the surface tension between the resin, which is solid at 20°C, and water. The surface tension of the resin at 20°C obtained by measuring the contact angle of the resin and the surface tension calculated by the same method as above at a temperature just above the melting temperature of the resin instead of the predetermined temperature. Find it from the value using the inner method.

In the present invention, in order to separate the mixed upper layer paint and lower layer paint by heating or melting and form a complete multilayer coating film, the resin between both paints must be attracted to the surface to be coated. There needs to be a difference.

Selective attraction of the molten resin to the coated surface is controlled by a combination of factors such as its melting temperature range, surface tension, viscosity, and specific gravity.

The present inventor believes that the "multilayer formation composite parameter" (hereinafter referred to as "multilayer formation composite parameter") measured by the test method described later is an index that quantitatively indicates the extent to which molten resin is attracted to the polar surface of metal, glass, ceramics, etc. The difficulty of forming a multilayer coating film can be determined most easily by the ratio of the multilayer parameter values of the resin in the upper layer paint and the resin in the lower layer paint. revealed.

In other words, in order for the combined resin in the upper layer paint and the resin in the lower layer paint to form a multilayer, the ratio of the dog to the small in their multilayer parameters must be 1.5 or more. It is desirable that the value is 1.8 or more, and particularly preferably 2.0 or more.

If this ratio is closer to 1 than 1.5, the separation between the resins in both mixed paints will be insufficient, especially in the lower part of the paint film, resulting in an incomplete multilayer with a large degree of irregularity. There is a risk of forming a paint film.

Specifically, in order to form the first pattern coating film, the multilayer parameters of the resin in the lower layer paint are two colors or each resin (two types) in the upper layer paint consisting of powder paint of two or more colors. (above), and the ratio thereof must be 1.5 or more, and if this condition and each of the above conditions are satisfied, a coating film as the object of the present invention having a multicolored pattern on the upper layer is formed. be done.

In addition, in order to form the second pattern coating film, two colors or a mixture of powder paints of two or more colors are used as the lower layer paint,
This can be obtained by making the multilayer parameter of each resin contained in the lower layer paint larger than that of the resin in the upper layer paint, similar to the first pattern coating film.

Furthermore, the multilayer parameter ratio between the resins in the powder coating mixture of two colors or two or more colors is preferably in the range of less than 1.5 to 0.66 or more, and particularly preferably about 1. be.

To measure the multilayer parameters, as shown in the drawing, a fixed amount of solid resin to be measured of 0.15.9 mm is placed inside a heat-resistant glass cylinder 1 with an inner diameter of 12 mrIL, and a solid resin to be measured is placed on top of the solid resin. , outer diameter 4. Omrn1 inner diameter 2.53mrIt
Pyrex glass tube 2 whose inner surface is thoroughly cleaned
is made to stand upright so as to be coaxial with the cylindrical container 1 and to be able to freely hang down due to gravity.

This thin tube 2 has its lower end surface polished so that it is perpendicular to the axis, and a notch or guide hole 3 is provided in the lower end portion to allow the molten resin to be measured to flow freely. It is.

The entire measurement system is stored in a constant temperature chamber maintained at a predetermined measurement temperature (T'C) so that the bottom surface of the cylindrical container 1 is horizontal, and the resin to be measured is melted to form a layer 4 of molten material. let

The thin tube 2 hangs down as the resin to be measured melts, and its lower end surface reaches the bottom surface of the cylindrical container 1, and at the same time, the molten material flows into the thin tube 2.

The liquid surface of the molten resin to be measured not only forms a meniscus inside the capillary tube 2, but also advances on the inner wall surface of the capillary tube 2 by a so-called "creeping" phenomenon.

The rate of creeping indicates the extent to which the resin to be measured is attracted to a polar coating surface such as glass, and the creeping rate indicates the degree to which the resin to be measured is attracted to a polar coated surface such as glass. Height from the bottom of 1 Ht(n
) is measured, and the density of the melt ρ (g/crib
, ), it is most preferable to use the product ht, (g/crtt) as the multilayer parameter.

It is most preferable and practical to measure the multilayer parameters at a temperature immediately above the highest melting temperature of each component resin for each coating powder resin mixture.

In the case of other component resins for which it is difficult to measure multilayer parameters by continuing heating at that temperature for 25 minutes due to decomposition and curing, etc., it is difficult to measure multilayer parameters by continuing heating at that temperature for 25 minutes, so there is no risk of such difficulty occurring from just above the melting temperature of the resin. Measurements are made at two or more temperature ranges within the temperature range, and the multilayer parameters at the same predetermined temperature are calculated and compared using the removal method.

Alternatively, reduce the heating duration to less than 25 minutes and
There is no significant difference even if the conversion is performed assuming that the rising speed of the tip is uniform.

Powder coating resins that can be applied to the present invention include combinations that have the above-mentioned relationships in terms of affinity parameters, melt surface tension, multilayer parameters, and compatibility. It does not matter whether it is thermoplastic or thermosetting, and there is no particular restriction.

For example, polyvinyl chloride, polyvinyl fluoride, polyvinylidene chloride, polyvinylidene fluoride, polystyrene,
Polyvinyl Toluev, As (ac90 nide 9 styrene) resin, ABS (acrylonitrile butadiene)
styrene) resins, silicon derivatives (e.g. silicon acetate, silicon acetate lactate, etc.), polyesters (e.g. polyethylene terephthalate, polybutylene terephthalate, etc.), epoxy resins (e.g. polycondensates of bisphenol A and shrimp chlorohydrin, etc.) , phenoxy resins, polyolefins (e.g. polyethylene, polypropylene, etc., also including copolymers of olefins and vinyl esters such as vinyl acetate), acrylic resins (methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, 2-hydroxyethyl In addition to polymers or copolymers of methacrylic acid esters such as MEC 9-late, glycidyl methacrylate, or acrylic acid esters such as methyl acrylate, as well as these monomers,
Vinyl monomers such as styrene, acrylonitrile, acrylamide, N-methylolacrylamide, N-vinylpyridine, methacrylic acid, acrylic acid, etc.
copolymerized at a ratio of % by weight or less), ketone resin, coumaron resin, polyamide polycarbonate, urea/formaldehyde resin, melamine/formaldehyde resin, phenol/formaldehyde resin, polysulfone, ionomer resin, polyimide, natural resin (rosin) , shellac, copal, etc.) or processed products thereof, polyvinyl acetate, polyvinyl alcohol (partially or completely saponified polyvinyl ester), or its acecooled products (e.g. polyvinyl butyral, polyvinyl formal, etc.), etc., in the form of powder or fine particles. The present invention can be applied to any material that can be selected and combined in consideration of the above conditions, as long as it can become a melt at least temporarily by heating and form a coating layer after cooling. .

Even if these resins are of the same type, they can be combined to form a multilayer coating film if the limiting conditions of the present invention are satisfied due to differences in degree of polymerization, stereoregularity, etc.

The degree to which these resins are made into powder is sufficient as long as the particle size does not pose a problem for application by any powder coating method to be applied, such as electrostatic method or fluidized bed dipping method, and the particle size distribution should be Precise adjustment is not particularly necessary for the purpose of forming a multilayer coating film, but it is desirable to prevent coarse particles with a particle size of 300 microns, particularly preferably 100 microns, from remaining. - By making the particle size of the component resin powder having a relatively small size, in relation to the ease of melting,
Formation of a multilayer, especially separation of components on the lower layer side, can be further promoted.

The mixing ratio of each component powder resin should be such that the amount of each component to be separated by melting to form multicolored patterns and multilayers is less than 10% by weight, particularly preferably less than 30% by weight of the total amount. Components mixed in a ratio of less than 10 parts by weight cannot constitute a complete multilayer.

Non-melting powder components such as coloring pigments, fillers (extending pigments), rust preventive pigments, and metal powders can be dispersed in these resins by applying commonly known powder coating manufacturing techniques.

In addition, liquid or fusible solid components that are compatible with one or each of the resin components to be separated, such as plasticizers, hardeners, soft solid resins that cannot be liquefied or powdered, and which form a multilayer A fusible powder resin that does not meet the limits of the present invention in terms of affinity or compatibility with the powder resin component to which the resin is applied is added to the multilayer-forming powder resin at a rate of, for example, 10% by weight or less. This can also have the effect of facilitating the formation of multiple layers or improving the smoothness and gloss of the coating.

The resins to be multilayered may be mixed before being pulverized. That is, the present invention is applicable even when three or more resins are mixed in the same particle.

In the multicolored pattern finishing method according to the present invention, in order to form the first pattern coating film, for example, if necessary, an anticorrosive pigment or the like is dispersed or powdered into a resin having the above-mentioned conditions of excellent adhesion to the object to be coated. Color pigments are dispersed and powdered to form a desired multicolored pattern in two or more resins satisfying the above conditions as an upper layer paint. .

The three or more types of powder coatings thus obtained are uniformly mixed, applied in the same manner as ordinary powder coatings, heated, melted, and separated to form the multicolored pattern coating that is the object of the present invention. A membrane is obtained.

Next, in order to form the second pattern coating film, the upper layer coating is made of a resin that meets the above-mentioned specific conditions and has excellent smoothness, weather resistance, etc. A desired multicolored pattern can be formed using two or more resins that satisfy the specific conditions mentioned above as a lower layer paint that forms a multicolored pattern. The desired multicolored patterned coating film can be obtained by uniformly dispersing and mixing the necessary colored pigments and powdering them, applying them using a conventional method, heating, melting, and separating them.

In the case of the first pattern coating film, the multicolored pattern in the present invention can be easily adjusted by changing the blending ratio of the powder coating of two or more colors contained in the upper layer coating and the type of color pigment. In the case of a two-pattern coating film, the lower layer paint may be changed in the same way.

The distribution of each component resin in each part of the multilayer coating film formed by the method of the present invention can be confirmed and quantified by various methods.

For example, if colored pigments with different colors for each component are pre-dispersed and mixed as a powder, multi-layering can be achieved by observing the cross section of the cured paint film, or by polishing it from the top and watching the colors change sequentially. You can check it.

In addition, even if it is not possible to distinguish by color, it is possible to analyze the composition of the powdered resin produced by polishing the paint film by, for example, observing the infrared absorption spectrum, or by observing the infrared reflection spectrum of the exposed polished surface. method is used.

By carrying out the method of the present invention, a single powder coating process is suitable for adhesion, corrosion resistance, etc., or weather resistance, gloss, smoothness, etc., depending on the purpose of use. It has excellent film performance, and allows for a multi-colored pattern finish with a paint that makes painting work pollution-free, making it extremely useful for streamlining painting work.

Examples are shown below.

Example 1 Ebiko) 1004 (trade name manufactured by Shell Kagaku ■) (Surface tension 27.9 dyne/crrt, multilayer parameter 0
．． 66) After tri-blending 100 parts of adipic acid hydrazide, 6.5 parts of titanium white (rutile type), 40 parts of titanium white (rutile type), and 1 part of a coating surface conditioner for 3 to 10 minutes using a heating roll, the mixture was heated to 90°C for 10 minutes using a heating roll. The mixture was melt-kneaded for a minute.

Then, after cooling, a powder coating A having a particle size of about 20 to 100 μm was obtained using a pulverizer.

Desmofene DH-650 (trade name manufactured by Bayer, polyester resin) (Surface tension 28.3 dyne/cIr
Powder coating B was produced in the same manner as powder coating A using 100 parts of L1 multilayer parameter (0.63), 5 parts of carbon black, and 1 part of coating surface conditioner.

Plexigum N-80 (trade name acrylic resin manufactured by Rohm Co., Ltd.) (Surface tension 22.7 dyn
Powder coating C was prepared in the same manner as powder coating A using 100 parts of e/cIrL, multilayer parameter 0.20) and 1 part of a coating surface conditioner.

The relationships among the affinity parameters, multilayer parameters, and surface tensions of the resins used in these powder coatings A, B, and C are shown in the following table.

Therefore, powder coatings A and B are the lower layer coatings,
Powder paint C becomes the upper layer paint.

The above powder coatings A, B and C are 1:1 as resin solid content.
:1 (weight ratio), coated to a film thickness of 150 μm using a conventional electrostatic coating method, and baked at 180° C. for 20 minutes.

The resulting painted surface had a clear black spot-like pattern on a white background, and when the paint film was cut perpendicular to the surface to be coated and the cross section was observed, the upper layer was mainly a transparent paint film. In the lower layer, the white and black painted surfaces were clearly separated.

Example 2 100 g of Epicoat (manufactured by Shell Chemical Co., Ltd., trade name (surface tension 31.3 dyne/cm, coating parameter 0.2)
6) 100 parts of adipic acid hydrazide, 6.5 parts of titanium white (rutile type), and 1 part of a coating surface conditioner were triblended, kneaded, melted and ground in the same manner as in Example 1 to obtain powder coating A.

Example using 100 parts of Mobilis M-30 (trade name vinyl acetate resin manufactured by Hoechst) (surface tension 27.3 dyne/crIL, multilayer parameter 0.33), 5 parts carbon black, and 1 part coating surface conditioner. Powder paint B was obtained in the same manner as in Example 1.

Example 1 was prepared using 100 parts of AP Stable (trade name polyurethane resin manufactured by Bayer) (surface tension 38.5 dyne/cm, multilayer parameter 1.38), 30 parts iron oxide, and 1 part coating surface conditioner. Powder coating C was obtained in the same manner.

The relationships among the affinity parameters, multilayer parameters, and surface tension of the resins used for these powder coatings A, B, and C are shown in the table below. Powder coatings A and B are the upper layer coatings, and the powder coatings C is the lower layer paint.

The above powder coatings A, B and C are resin solid content: 1:
Mix at a ratio of 1:1 (weight ratio), apply to a film thickness of 150μ using the usual electrostatic coating method, and apply at 190°C.
and heated for 20 minutes.

The resulting painted surface has a clear black spot-like pattern on a white background, and when the paint film is cut perpendicular to the surface to be coated and the cross section is observed, the upper layer mainly shows a patterned paint film. The lower layer was a coating film containing iron oxide pigment.

In addition, the surface tension in each of the above examples was measured at 200°C, and the multilayer parameter was measured at the baking temperature of the coating film in each example.

Comparative Examples 1 to 10: Regarding powder coatings A, B, and C manufactured according to Example 1, the mixing ratio, coating method, film thickness, baking conditions, etc. of these powder coatings A, B, and C were all the same as Example 1. and 2, experiments were conducted as shown in Tables 1 and 2.

The condition of the obtained coating film is also as shown in Tables 1 and 2.

[Brief explanation of the drawing]

The drawing is a cross-sectional view schematically showing a measurement system used for measuring multilayer parameters. 1... Cylindrical container, 2... Thin tube, 3...
... Notch or guide hole, 4 ... Melt layer, 5 ... Creeping part.

Claims (1)

[Scope of Claims] 1. A mixture of a powder coating for the lower layer and a powder coating for the upper layer consisting of two colors or a mixture of two or more colors is applied to an object to be coated, and heated, melted, and separated. The multicolored pattern finish powder coating coating method is characterized in that: ■ the affinity parameter between each of the powder coating resins is a positive number, 0, or an absolute value of 0;
．． be a negative number less than 10; ■ the surface tension of the powder coating resin for the lower layer is 0 greater than each resin in the powder coating for the upper layer;
．． 5 dyne/cm or more, and the difference in surface tension between each resin in the powder coating for the upper layer is 5. Odyne
/cm or less, and (ii) the layer formation composite parameter of the powder coating resin for the lower layer is larger than that of each resin in the powder coating for the upper layer, and the ratio thereof is desirably 1.5 or more. A method for finishing a multicolored pattern using a powder coating, characterized in that the multilayer formation composite parameter ratio between each resin in the powder coating for the upper layer is from less than 1.5 to 0.66 or more. 2 A multicolored pattern finished powder obtained by applying a mixture of a powder coating for the upper layer and a powder coating for the lower layer consisting of two colors or a mixture of two or more colors to the object to be coated, heating, melting, and separating the mixture. In addition, the affinity parameter between each of the powder coating resins is a positive number, 0, or an absolute value of 0.
．． be a negative number less than 10; ■ the surface tension of each resin in the powder coating for the lower layer is 0 greater than that of the powder coating resin for the upper layer;
．． The difference in surface tension between each resin in the powder coating for the lower layer is greater than 5 dyne/cIrL. Odyn
e/cm or less; (ii) the multilayer formation composite parameter of each resin in the powder coating for the lower layer is larger than that of the powder coating resin for the upper layer, and the ratio thereof is 1.5 or more; A method for finishing a multicolored pattern using a powder coating for a lower layer, characterized in that the multilayer formation composite parameter ratio between each resin in the powder coating for the lower layer is from less than 1.5 to 0.66 or more.