JPS6136028B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for the production of multilayer metallic coatings containing particulate metal and comprising two or more layers of dissimilar resins or resin compositions in a single application step. An object of the present invention is to provide a powder coating that can be formed on the surface of an object.

Conventionally, various attempts have been made to form a metallic coating on the surface of an object using a powder coating. For example, a powder coating obtained by dispersing particulate metal such as aluminum powder in powdered resin is applied to the surface of an object using an electrostatic coating method, and then melted and hardened to obtain a metallic coating film. can. However, with this method, it is generally difficult to orient the particulate metal parallel to the coating surface, and the particulate metal is often exposed on the coating surface. As a result, the appearance of the paint film lacks a so-called metallic feel, causing problems such as early discoloration of the exposed metal surface due to air oxidation, and lack of ability to protect the substrate for moisture penetration due to the generally rough paint film structure. , and its practicality is low.

These drawbacks can be solved by covering the surface of the particulate metal in advance with a resin component, for example, the same type of resin as the powdered resin that is the main component of powder coatings, or by applying high temperatures during baking of the coating film to melt it. This can be alleviated to some extent by allowing the resin to flow sufficiently, but it is not perfect, and in order to avoid exposing particulate metal to the coating surface, it is necessary to overlay another paint that does not contain particulate metal. It was necessary to paint it.

In general, when applying paint two or more times to form a paint film on the interface of metal, etc., the side in contact with the surface to be coated (hereinafter referred to as the "lower side") and the side in contact with the external atmosphere (hereinafter referred to as the "upper side") ''), or for the middle layer, two or more coating processes are applied using different types of paints each having properties suitable for each. In order to avoid such complexity, the present inventor provided a method of forming a multilayer coating film at once using a powder coating (see, for example, Japanese Patent Application Laid-Open No. 122137/1983). It has been extremely difficult to form an excellent multilayer metallic coating film using a powder coating as it is, since the particulate metal is distributed into the upper layer and is not perfectly oriented. Therefore, as a result of further intensive research, the present inventors have been able to provide a powder coating for forming a multilayer metallic coating film that can exhibit the desired effects according to the present invention. That is, the present invention includes two or more resins or resin compositions in powder form and particulate metal, and at least one of the two combinations selected from the resins or resin compositions has (a ) are incompatible or poorly compatible, (b) there is a substantial difference in surface tension of the melt at the same temperature, and (c) there is a substantial difference in the composite parameters of multilayer formation, and The resin or resin composition having the non-minimum surface tension is thermosetting, and the particulate metal is further encapsulated by a wetting agent which, in the molten state, binds the resin or resin composition. It is a crosslinking agent or a reaction accelerator for the thermosetting resin or resin composition, which has a surface tension that is substantially higher than the minimum surface tension of any of the materials. This is a powder coating for forming multi-layer metallic coatings.

The powder coating material of the present invention contains as main components powder of a resin or resin composition for forming each layer of a multilayer metallic coating film, and particulate metal covered with a wetting agent. The powdered resin or resin composition may be thermosetting or non-thermosetting as long as it can be melted by heat.
Furthermore, it is a powder of a resin composition in which additives such as a crosslinking agent and a reaction accelerator for thermal curing are mixed or dispersed, and two or more of them are mixed. At least one of the two combinations selected from these powders forms a multi-layered coating film by utilizing phase separation during thermal melting, so the mutual relationship between them is (a). (b) there is a substantial difference in the surface tension of the melt at the same temperature; and (c) there is a substantial It is necessary that there be a significant difference.

The lower the degree of mutual compatibility between the two powders to be phase-separated, the more clear the formation of multiple layers, which is advantageous. If it is low, there is a risk that the multilayer formation will be incomplete, so it is desirable to understand the degree numerically. The degree of compatibility between two types of resins or resin compositions can be expressed numerically by an "affinity parameter" that can be determined by the measurement method described later. It is also preferred to use affinity parameters. In the case of the present invention,
When the mutual affinity parameter between two types of resins or resin compositions is a positive number, 0, or a negative number with an absolute value of less than 0.10, especially when it is a positive number, there is a difficult relationship between the two types. Since the degree of solubility is high and phase separation is easy, it is particularly easy to form a metallic multilayer coating film.

The above affinity parameters are measured by observing the mixing state of both types of resins in solution under certain test conditions, and the affinity parameters determined by this method are as follows: It is most preferable as an index regarding the degree of affinity between resins, which is an essential element in the present invention. Specifically, a mixture of equal volumes of toluene and methyl isobutyl ketone (MIBK) was used as a solvent, and each of the test soluble resins was made into a solution with a resin content of 33% by weight, and the solution was obtained at 25°C. Mix equal weights of the two solutions. After stirring the mixture to make it sufficiently homogeneous, look through the 5 cm thick liquid layer with the naked eye under natural daylight and if it is completely transparent, it indicates the affinity of the combination of the two resins. The parameter is 0 or 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 (OH ₃ OCH ₂・CH ₂ OCOCH ₃ ) dropwise to this mixed solution while stirring it, if the number is positive. This leads to the disappearance of turbidity due to the effect of , and the destabilization of the solute accompanying the addition of 0 or a negative number leads to the generation of turbidity. The numerical value of the affinity parameter P is calculated by the following formula.

|P|=△D/A+B+C+△D×K However, A and B: Weight of each of the two resins in the mixed solution (g) C: Weight of the solution in the initial mixed solution (g) △D: Dripping Weight (g) of either solution K: Correction coefficient, 1 when P is a negative number, 100/45 when P is a positive number. When P does not reach the minimum display unit, P is set to 0.

If at least one of the two resins is insoluble in the mixed solvent, it is impossible to determine the affinity parameter using the above method, but the approximate numerical value can be indirectly determined using another method. You can know. That is, in the case of insoluble or poorly soluble resins such as polyethylene and polyamide, the thickness obtained by molding the resin is 400 to 500 μm.
The straight edges of the sheet are placed on a glass surface in close contact with each other, heated to a temperature sufficient to completely melt both resins, and held for about 30 minutes. The affinity parameter between both resins, etc. is a positive number, 0, or an absolute value
If it is a negative number less than 0.10, an interface or boundary layer will be formed between the two types of molten resin, resulting in discontinuity, but if it is a negative number with an absolute value of 0.10 or more, it will be discontinuous due to mutual diffusion. The composition changes continuously and no discernible interfaces are formed. The presence or absence of such an interface can be observed more easily with the naked eye by dispersing a colored pigment or dye such as carbon black in at least one of the two types of resins to create a color change. can.

The combination of two types of resins used in combination for the purpose of forming a multilayer coating film not only requires that the affinity parameter observed in the solution state be within the above range, but also in the state with the solvent removed. They also need to be incompatible or poorly compatible. 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 (at room temperature, for 24 hours) to form a dry film. It is necessary to observe turbidity or resin separation by observing transmitted light and scattered light. If at least one of both resins etc. is insoluble in the mixed solvent,
The fact that the formation of an interface, etc. was observed in the above-mentioned sheet melting test can be considered to indicate incompatibility or poor compatibility between the two types of resins.

At the same time, between mutually incompatible or poorly compatible resins, etc., which are the main components of the powder coating of the present invention and are intended to form a multilayer through phase separation,
It is also necessary that there be a substantial difference in surface tension of the melts at the same temperature. In other words, a resin having a low surface tension is thermally melted to undergo phase separation and flow, thereby forming the upper portion of the multilayer metallic coating film. In order to reliably prevent exposure of particulate metal, it is necessary that the layer containing particulate metal is a lower or intermediate layer and is completely covered by a layer that does not contain particulate metal. Particularly, complete phase separation of the components in the surface layer portion of the multilayer coating film is required. Therefore,
It is necessary that there is a substantial difference between the surface tensions of these resins, preferably a difference of 2.0 dyne/cm or more, and it is difficult to find a resin etc. that has a surface tension between these two. It is desirable that powders with a low degree of solubility are not used. If the difference in surface tension of the melt is not substantial between any two combinations of powdered resins, the formation of the coating film will be incomplete, or particles will There is a risk that some of the metal may be exposed on the coating surface.

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 powder resin mixture for coating, 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 the temperature at which the coating film is formed, but in practice, in the case of any mixture, the temperature is set at a constant temperature, for example, 200°C, and the value of the surface tension at that temperature is calculated. There is no problem and it is convenient to use and compare.

There are no particular restrictions on the method of measuring the surface tension δL (dyne/cm) of a resin melt, but for example, from the measured value of the contact angle θ between the melt and Teflon (tetrafluoroethylene resin), the following Neumann ) and Sell's equation.

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

Regarding the method of measuring the contact angle of molten resin to Teflon at a predetermined temperature, for example, 200℃,
Any method that can be used to determine the advancing contact angle can be applied without any particular restrictions. Then, it is melted and cast in a constant temperature chamber maintained at a predetermined temperature, and when equilibrium is reached, it is enlarged and projected or observed with a telescope.

If the melting temperature of the resin, etc. 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, the resin, etc., which is solid at 20°C, and water The surface tension value of the resin, etc. at 20°C obtained by measuring the contact angle with It is determined from the value of surface tension using the internal method.

In the present invention, in order to separate mixed powder resins etc. by heating and melting and form a complete multilayer coating film, there is a substantial difference in the degree to which each resin etc. is attracted to the surface to be coated. It also requires that there be. Selective attraction of molten resin and the like to the surface to be coated 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 "multiple layer formation composite parameter") measured by the test method described later is an index that quantitatively indicates the degree to which molten resin, etc. is attracted to the polar surface of metal, glass, ceramics, etc. It has been clarified that the difficulty of forming a multilayer coating film can be most easily determined by the ratio of the numerical values of this coating parameter for each component resin. In order for the two combined resins to clearly separate, particularly in the lower portion of the multilayer coating, there must be a substantial difference between the multilayer parameters. In the case of the present invention, combinations of the two resins mentioned above that satisfy the requirements for phase separation in terms of incompatibility and surface tension should also have a substantial difference in this coating parameter; It is usually preferable that the ratio of large to small is 1.1 or more. If this ratio is close to 1, there is a risk that the separation between the mixed resins, etc. will not be sufficient, especially in the lower part of the coating, resulting in an incomplete multilayer metallic coating with a large degree of irregularity. There is.

To measure multilayer parameters, as shown in Figure 1, a fixed amount of 0.15 g of solid resin to be measured is placed inside a heat-resistant glass cylindrical container 1 with an inner diameter of 1.2 cm, and the solid resin is placed on top of the solid resin. , outer diameter 4.0mm, inner diameter 2.53
A Pyrex glass thin tube 2 whose inner surface has been thoroughly cleaned is stood upright so that it is coaxial with the cylindrical container 1 and can freely hang down due to gravity. This thin tube 2 has its lower end surface polished so as to be perpendicular to the axis, and a notch or guide hole 8 is provided at the lower end portion to allow the molten material such as the resin to be measured to freely flow therein. It is something. The entire measurement system is stored in a constant temperature chamber maintained at a predetermined measurement temperature (T°C) with the bottom of the cylindrical container 1 being horizontal, the resin to be measured, etc. is melted, and a layer 4 of the molten material is formed. Let it form. The thin tube 2 hangs down as the resin to be measured, etc. melts, and its lower end surface is connected to the cylindrical container 1.
reaches the bottom surface of the tube 2, and at the same time the melt flows into the inside of the capillary tube 2. The liquid surface of the molten material such as the 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. this
The creeping speed indicates the degree to which the resin to be measured is attracted to the polar coating surface such as glass, and the creeping speed is the degree to which the resin to be measured is attracted to the polar coating surface such as glass. The height Ht (cm) from the bottom of 1 is measured, and the product ht (g/cm ² ) obtained by multiplying this Ht by the density ρ (g/cm ³ ) of the melt can be used as the multilayer parameter. Most preferred.

It is most preferable and practical to measure the multilayer parameters at a temperature immediately above the highest melting temperature of each component resin, etc. of each powder coating. 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, curing, etc., such difficulties arise from just above the melting temperature of the resin, etc. Measurements are taken at two or more temperature ranges within a temperature range where there is no risk, and the multilayer parameters at the same predetermined temperature are calculated and compared using the detachment method. Alternatively, if the heating duration is shortened to less than 25 minutes and the rising speed of the tip of the creeping portion 5 is uniform, no significant difference will occur.

If there are three or more types of powder resin etc. to be mixed, for all combinations of two of them,
It is not necessary that the surface tension and the multilayer parameter simultaneously have a relationship within the above limits, but if at least one of each combination has such a relationship, the other combinations are limited only with respect to one of the indicators. By being fulfilled,
A multilayer structure of three or more types can be easily formed.

Powder resin, which is the main component of the powder coating for forming multilayer metallic coatings according to the present invention, can be widely thermosetted if it satisfies the necessary conditions in terms of compatibility, melt surface tension, and multilayer parameters as described above. The thermosetting resin can be selected from thermosetting resins and non-thermosetting resins, and specifically, the following can be mentioned.

For example, polyvinyl chloride, polyvinyl fluoride, polyvinylidene chloride, polyvinylidene fluoride, polystyrene, polyvinyltoluene, AS
(acrylonitrile, styrene) resin, ABS (acrylonitrile butadiene styrene) resin,
Silicon derivatives (e.g. silicon acetate, silicon acetate lactate, etc.), polyesters (e.g. polyethylene terephthalate, polybutylene terephthalate, etc.), epoxy resins (e.g. polycondensate of bisphenol A and epichlorohydrin, etc.), phenoxy resins , polyolefins (including polyethylene, polypropylene, etc., and copolymers of olefins and vinyl acetate), acrylic resins (methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, 2-
Polymers or copolymers of methacrylic esters such as hydroxyethyl methacrylate and glycidyl methacrylate, or acrylic esters such as methyl acrylate, and in addition to these monomers, styrene, acrylonitrile, acrylamide, N-methylolacrylamide, Copolymerized vinyl monomers such as N-vinylpyridine, methacrylic acid, and acrylic acid in a proportion of 40% by weight or less), ketone resins, coumaron resins, polyamides, polycarbonates, urea formaldehyde resins, Melamine/formaldehyde resin, phenol/formaldehyde resin, polysulfone, ionomer resin, polyimide, natural resins (rosin, Sierra, Kobal, etc.) or their processed products, polyvinyl acetate, polyvinyl alcohol (partially or fully saponified polyvinyl ester) or their Acetalized products (e.g. polyvinyl butyral, polyvinyl formal, etc.), which can be made into powder or fine particles, become at least temporarily molten by heating, and can form a coating layer after cooling. , the present invention can be applied to any of them by selecting and combining them in consideration of the above conditions.
Even if these resins are of the same type, they can be combined to form a multilayer metallic coating film if the restrictive conditions of the present invention are satisfied due to differences in condensation polymerization composition, degree of polymerization, stereoregularity, etc. can be done.

The degree to which these resins, etc. are made into a powder is sufficient as long as the particle size does not pose a problem for coating 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 relatively small, it is possible to further promote the formation of multiple layers, especially the separation of the components on the lower side, due to the ease of melting. can. The mixing ratio of each component powder resin is determined based on the total amount of each component that is to be separated by melting to form a multilayer.
It is necessary to ensure that the amount is not less than 10% by weight, particularly preferably less than 30% by weight, and 10% by weight
If the components are mixed in a ratio lower than that, there is a possibility that a complete multilayer cannot be formed.

The type of particulate metal that is the main component of the powder coating of the present invention is not particularly limited as long as it is normally used in the production of solution-type metallic coatings, and examples include aluminum, copper, zinc, iron, Targets include nickel, chromium, cobalt, gold, silver, lead, tin, etc., and alloys containing them. If the particles have a flake shape, it is easy to visually check the state of orientation within the multilayer coating film, and the benefits of implementing the present invention are particularly significant. However, there is no hindrance to the application of the present invention. Regarding the size of the particles, if they are flaky or acicular, the maximum diameter or length may be, for example, 2 mm or less, particularly preferably 0.5 mm or less,
In the case of bulk particles, their maximum diameter may be smaller than the thickness of the multilayer metallic coating film to be formed. The proportion of these particulate metals contained in the powder coating is 1 to 60% by volume.
%, particularly preferably 2 to 30%. If this lower limit is not reached, the effect of adding particulate metal will be poor; if this upper limit is exceeded, on the other hand, particulate metal will tend to be exposed on the coating surface.
This makes it difficult to achieve the object of the present invention.

The surface of the particulate metal, which is one of the main components of the powder coating of the present invention, must be covered with a wetting agent. Infiltrating agents used for this purpose include a wide range of non-volatile agents that have affinity with the surface of particulate metals and are compatible with resins, etc. that form the lower or middle layer of multilayer coatings in the molten state. However, in order to ensure that part of the particulate metal is not exposed to the surface of the multilayer coating, the surface tension of the melt can be selected from powder resins. etc. It is necessary that the difference is larger than the smallest one and has a substantial difference, and preferably the difference is 2.0dyne/
It is preferable to use one with a diameter of cm or more. In addition, if this infiltrant is in solid form, it should be melted at a temperature as low as possible, preferably below the baking temperature of the coating, in order to facilitate the movement and orientation of the particulate metal during baking of the multilayer coating. It is better to use one that does.

The layer in which particulate metal is to be dispersed in a multilayer coating film, that is, the resin, etc. that constitutes the lower or middle layer, is thermosetting, and requires the combined use of a crosslinking agent or reaction accelerator. If the crosslinking agent, etc. meets the above-mentioned requirements as an infiltrating agent, a part of it can be regarded as an infiltrating agent and can be used for enveloping particulate metal. When particulate metal is covered with a crosslinking agent etc. in this way, a high-density crosslinked molecular structure is formed on the surface of the particulate metal, which not only increases mechanical stability but also improves the surface of the particulate metal. Since it can prevent moisture, gas, etc. from penetrating along the surface, it is preferable for improving various properties of multilayer metallic coatings, such as water resistance, chemical resistance, weather resistance, etc.

Specific examples of infiltrating agents used for enveloping particulate metal include the following, which are made into a solution with a volatile organic solvent and mixed with particulate metal free of impurities, Encapsulation treatment is performed by any method such as volatilization of a solvent, and the mixture is mixed with a powdered resin or the like. Furthermore, the effects of the present invention can be further enhanced by using a material that has been subjected to enveloping treatment under conditions that cause chemical bonding between particulate metal and powdered resin.

〔example〕

resorcinol pyrogallol 1,3-dihydroxynaphthalene 2,2'-dihydroxydiphenyl 3,4-dihydroxybenzaldehyde 2,4-dihydroxybenzophenone P-benzophenone P-hydroxybenzyl alcohol 2,2'-diaminoazobenzene 4,4' -Diaminobenzophenone P-Ethyl hydroxybenzoate N-methylacetanilide 1,2-naphthylenediamine n-butylamide 2,6-dichloronaphthalenemethylacridine (9) Diacetylcarbazidobenzoylthiourea P-chloroacetanilide P,P'- Isopropylidene diphenol (Bisphenol A) P,P'-dihydroxydiphenylmethane (Bisphenol F) Blocked isocyanate compounds, such as tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate blocked with phenols, lactams, etc. ,4,
4′-diphenylmethane diisocyanate, isophorone diisocyanate, etc.

Low molecular weight addition condensates of formaldehyde and polyamino compounds such as melamine, guanamines, urea and thiourea, or their derivative phenols, or low molecular weight addition condensates of formaldehyde and hydrocarbon group-substituted phenols (P-cresol, P-phenylphenol, etc.). Molecular weight addition condensate or its derivative polyhydric carboxylic acid dibutyltin dilaurate detraethylammonium bromide Powder coatings whose main components are these powdered resins, etc. and encapsulated particulate metals also contain colored pigments and fillers. Non-melting powder components such as extender pigments and anti-rust pigments can be dispersed. In addition, liquid or acidic solid components that are compatible with one or each of the resin components to be separated, such as a plasticizer,
Soft solid resins that cannot be liquefied or powdered, and fusible powder resins that do not meet the limits of the present invention in terms of affinity or compatibility with the powder resin component that forms the multilayer are used as main components. It can also be added to powdered resin, etc., in a proportion of 10% by weight or less, thereby making it easier to form a multilayer or improving the smoothness and gloss of the coating film. It will be done.

The powder resins to be mixed are of two types, A and B, which satisfy the limiting conditions of the present invention, and the surface tension is δ _A >
When _δB and the multilayer parameter is hA>hB, there will be a two-layer structure consisting of A on the lower side and B on the upper side, but if δA>δB and hA<hB, the coating film The upper surface portion and the lower adhesion surface portion both contain B as the main component, and the intermediate layer is mainly composed of A, resulting in a multilayer coating with a two-resin, three-layer structure.

The distribution of each component resin, etc. and particulate metal in each part of the multilayer metallic coating film formed by the method of the present invention can be confirmed and quantified by various methods. For example, if colored pigments of different colors are pre-dispersed and powdered for each component powder resin, etc. and mixed with particulate metal covered with an infiltrant, the cross section of the cured coating film can be observed or Multi-layering and distribution of particulate metal can be confirmed by polishing and observing the exposure of particulate metal and the sequential change in color. In addition, even if multi-layering cannot be distinguished by color, compositional analysis of the powdered resin produced by polishing and grinding of the coating film, for example, by observation of infrared absorption spectra, or infrared reflection of the exposed polished surface, can be carried out. Methods such as spectrum observation are used.

By carrying out the method of the present invention, multi-layer metallics can be coated in a single powder coating process, which is divided into parts that require advanced functions such as weather resistance and adhesion according to the purpose of use. Since the coating film is easily formed, it greatly contributes to streamlining the painting work.

Example 1 Acrylic with a number average molecular weight of about 10,000 obtained by copolymerizing 15% styrene (wt%, same hereinafter), 15% methyl methacrylate, 10% 2-ethylhexyl acrylate, 40% isobutyl methacrylate, and 20% glycidyl methacrylate. resin,
100 parts (parts by weight, same hereinafter) of Component A is ground with 17 parts of dodecanedicarboxylic acid so that the maximum particle size does not exceed 74μ and the average particle size is approximately 45μ.
And so. The multilayer parameters of this component A (value at 180℃, same below) are 0.35g/cm ² , surface tension (value at 180℃
(the same applies hereafter) was 30.6 dyne/cm.

Next, dimethyl terephthalate, isophthalic acid, adipic acid, neopentyl glycol, and trimethylolpropane were added in a molar ratio of 6:3:1:
Polyester with a number average molecular weight of about 9000 obtained by condensation at a ratio of 8:2.5 (multilayer parameter 0.55)
After adding and kneading 5 parts of phthalocyanine blue pigment to 100 parts (g/cm ² , surface tension 40.0 dyne/cm), a blocked isocyanate curing agent (isophorone diisocyanate blocked with ε-caprolactam, NCO group content 19%, Surface tension 59.3dyne/
cm) and grind to the same particle size as component A,
Component B (multilayer parameter 4.8g/cm ² , surface tension 45.8
dyne/cm).

Furthermore, bisphenol A (P,P′-isopropylidene diphenol, surface tension 58.0dyne/cm)
Mix 80 parts of acetone-washed aluminum flakes (manufactured by Toyo Aluminum Co., Ltd., product number #4919, maximum particle size 50μ) with 100 parts of a solution consisting of 0.5% and 99.5% acetone, and dry by spray drying to obtain the ingredients. I got a C.

The affinity parameter between component A and component B is
It was 0.30.

The weight ratio of component A, component B and component C is 40:
By mixing at a ratio of 60:5, a powder coating for forming a multi-layer metallic coating film (2) was completed.

The surface of this powder coating was pre-conditioned (Bonderite BN manufactured by Nippon Parkerizing Co., Ltd.).
#144 treatment liquid and Elekron #9000 electrodeposition paint manufactured by Kansai Paint Co., Ltd. were applied under predetermined conditions. ) It was applied to a mild steel plate (0.5 mm thick) using an electrostatic coating method, and was heated at 185°C for 35 minutes to form a film and harden it, resulting in a silver-blue polyester layer approximately 75 μ thick and A multilayer metallic coating was obtained consisting of a covering layer of transparent acrylic resin with a thickness of approximately 45μ.

Example 2 In the encapsulation of aluminum flakes, a solution of 1.0% blocked isocyanate curing agent and 99.0% acetone, identical to that used for component B, was used instead of a solution of bisphenol A. A powder coating for forming a multilayer metallic coating film (2) was completed by operating in the same manner as in Example 1, and a multilayer metallic coating film was obtained.

Comparative example: Aluminum flakes that were only washed with acetone and not particularly encapsulated were treated with component C.
An attempt was made to form a coating film in the same manner as in Example 1, except that the aluminum flakes were used as a layer. It was distributed evenly, and a part of it was exposed on the coating surface.

The coating film has properties such as water resistance (whitening, immersion at 40℃ for 1 week), weather resistance (glossy, slight discoloration, outdoor exposure for 1 year), and processability (Erichsen 1 mm, Erichsen Co., Ltd. coating film extruder). showed that.

Example 3 100 parts of an acrylic resin having a number average molecular weight of about 10,000, which is a copolymer of 12% styrene, 5% methyl methacrylate, 63% isobutyl methacrylate, and 20% glycidyl methacrylate, and 18 parts of dodecanedicarboxylic acid were ground together, and the A powder similar to component A was used as component D (multilayer parameter 0.32 g/cm ² , surface tension 27.9 dyne/cm).

Next, use another acrylic resin (styrene 35%, 2
~Copolymer of 20% ethylhexyl acrylate, 22% isobutyl methacrylate and 23% 2-hydroxyethyl methacrylate, number average molecular weight approx.
8000) 100 parts and red iron oxide pigment "Sicotrans Red 42" (manufactured by BASF, West Germany, trade name) 5
A blocked isocyanate curing agent (a mixture of equal weights of xylylene diisocyanate and isophorone diisocyanate blocked with benzyl alcohol. NCO group content
Add 30 parts of 20%) and grind to the same particle size as component E.
(Multilayer parameter 0.45g/cm ² Surface tension 30.5dyne/
cm).

Furthermore, 1.0% hexamethoxymethylolmelamine (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name "Cymel 350", surface tension 44.8 dyne/cm) and 99.0% methyl alcohol were added to the same type of aluminum flakes as in Example 1. Component F was obtained by enveloping using a solution consisting of:

The affinity parameter between component D and component E is
It was 0.1.

40 parts each of component D, component E and component F;
By uniformly mixing 60 parts and 10 parts, a powder coating for forming multilayer metallic coatings () was completed.

This powder coating was applied by electrostatic method onto a mild steel plate that had been surface-conditioned in the same manner as in Example 1.
The film is formed and cured by heating for several minutes to form a multilayer metallic coating consisting of a red metallic-like acrylic resin layer with a thickness of approximately 65 μm and a transparent acrylic resin layer with a thickness of approximately 85 μm covering it. Ta.

Example 4 100 parts of an acrylic resin having a number average molecular weight of about 10,000, which is a copolymer of 12% styrene, 5% methyl methacrylate, 63% isobutyl methacrylate, and 20% glycidyl methacrylate, and 18 parts of dodecanedicarboxylic acid were ground together, and the A powder similar to component A was used as component G (multilayer parameter 0.32 g/cm ² , surface tension 26.9 dyne/cm).

Next, use another acrylic resin (85% styrene, 2
- 100 parts of a copolymer of 20% ethylhexyl acrylate, 22% isobutyl methacrylate, and 23% 2-hydroxyethyl methacrylate, number average molecular weight approximately 8000) and red iron oxide pigment "Hikotransred 402" (manufactured by BASF, West Germany, Product name)
80 parts of a blocked isocyanate curing agent (a mixture of equal weights of xylylene diisocyanate and isophorone diisocyanate blocked with benzyl alcohol, NCO group content 20%) was added to the mixture, and the mixture was ground to the same particle size. Ingredient H
(Multilayer parameter 0.45g/cm ² , surface tension 29.5dyne/
cm).

Furthermore, an aluminum frame of the same type as in Example 1 was subjected to an enveloping treatment using a solution consisting of 0.5% 1,2-naphthylene diamine (surface tension 41.7 dyne/cm) and 99.5% acetone. did.

The affinity parameter between component G and component H is
It was 0.40.

The above component G, component H and component I, respectively
By uniformly mixing 45 parts, 55 parts, and 8 parts, powder paint for forming multilayer metallic coatings ()
completed.

Example 5 Methyl methacrylate 9%, styrene 18%, 2-ethylhexyl acrylate 19%, n-butyl methacrylate 39% and glycidyl methacrylate
Number average molecular weight obtained by copolymerizing 15%
100 parts of 12000 acrylic resin and 12.5 parts of dodecanedicarboxylic acid, the maximum particle size does not exceed 74 μ,
Component J was pulverized to an average particle size of about 45 μm. The multilayer parameter of this component A ₁ is 0.29g/
cm ² , and the surface tension was 30.7 dyne/cm.

Next, Epicote 1007 and Epicote 1004
Component K was obtained by mixing 20 parts and 80 parts of Trimellitic anhydride and 80 parts of rutile titanium oxide (both trade names, manufactured by Schiel Kagaku Co., Ltd.), respectively, and pulverizing the mixture to the same particle size. The multilayer parameter of this component B ₁ was 0.42 g/cm ² and the surface tension was 34.5 dyne/cm.

Furthermore, 30 parts of aluminum flakes of the same type as in Example 1 were mixed into 100 parts of a solution consisting of 1.0% tetraethylammonium bromide (surface tension 41.3 dyne/cm) and 99.0% ethyl alcohol, and then dried and subjected to enveloping treatment. Component L was obtained.

The affinity parameter between component J and component K is
It was 0.30.

40 parts each of component J, component K and component L;
By mixing in a ratio of 60 parts and 6 parts, a powder coating for forming a multilayer metallic coating () was completed.

In addition, the coating films obtained in Examples 1 to 5 have water resistance (no abnormality), weather resistance (good gloss and no discoloration compared to the coating film before baking), and processability (Erichsen 5 mm or more). (Test conditions were the same as above).

[Brief explanation of the drawing]

The drawing is a cross-sectional view schematically showing a measurement system used for measuring multilayer parameters.

Claims (1)

[Claims] 1 Comprising two or more resins or resin compositions in powder form and particulate metal, at least one of the two combinations selected from the resins or resin compositions is (a) incompatible or (b)
(c) there is a substantial difference in the surface tension of the melt at the same temperature, and (c) there is a substantial difference in the composite parameter of multiphase formation, and the surface tension is not the smallest among the resins or resin compositions. The particulate metal is thermosetting, and the particulate metal is covered with an infiltrating agent, and the infiltrating state in the molten state is thermosetting. A crosslinking agent or reaction accelerator for the resin or resin composition, which has a surface tension substantially greater than the minimum surface tension of any of the compositions and is thermosetting. A powder coating for forming multilayer metallic coatings characterized by the following.