Powder coatings, and electrical and electronic components

Abstract

To provide a powder coating composed of a thermosetting composition, which can form a cured product having high flame retardancy, while preventing a decline of flowability during melting.SOLUTION: A powder coating of the present invention is to form a cured product having a flame retardancy conforming to the UL94 V-0 standard. The powder coating is composed of a pulverized product of a thermosetting composition. The thermosetting composition comprises (A): a thermosetting compound, (B): a curing agent reactable with (A), (C): an organic flame retardant and (D): a flame-retardant aid. The (C) contains 90 mass% or more of (C1): a phosphate-containing compound and (C2): a phosphinate-containing compound but is free of (C3): a phosphorus compound compatible with a mixture of (A) and (B), with a mass ratio of (C2) to (C1) :1 being 0.2 to 0.8. The (D) contains 90 mass% or more of (D1): yellow iron oxide, with a mass ratio of (D1) to (C1):1 being 0.5 to 1.5.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a powder coating comprising a powdery thermosetting composition, which is suitable for use in the applications of electric and electronic components, particularly for encapsulating tantalum capacitor elements.

Background Art

[0002] Powder coatings comprising thermosetting compositions containing thermosetting resins such as epoxy resins are widely studied for use as encapsulants for electric and electronic components represented by integrated circuits such as capacitors, transistors, ICs, and LSIs, because their cured products are often excellent in heat resistance, electrical insulation, dimensional stability, etc. When a powder coating comprising a thermosetting composition is used as an encapsulant for electric and electronic components, the cured product obtained from the powder coating is required not only to have high heat resistance but also to have high flame retardancy (for example, V-0 level in the UL94 combustion test). Capacitors, particularly tantalum capacitors, have a problem that the encapsulation part of the exterior burns violently during a short circuit failure between the anode and cathode, that is, during burnout. However, the cured product obtained from a powder coating containing an epoxy resin has a problem of relatively poor flame retardancy and being easy to burn, so the addition of various flame retardants to the powder coating has been studied.

[0003] In response to the recent demand for halogen-free, there is known a powder coating comprising a powdery resin composition blended with a phosphorus compound as a flame retardant, which contains an epoxy resin, a phenolic resin, a phosphorus compound, and an inorganic filler surface-treated with a coupling agent (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a flame retardant is blended into a composition to enhance the flame retardancy of the cured product, the fluidity during melting of the powder coating may decrease due to this, resulting in deterioration of the paintability, and a smooth cured product may not be obtained. When the content of the flame retardant is increased to impart high flame retardancy to the cured product, in addition to this tendency becoming stronger, the blending ratio of other components in the composition relatively decreases, and as a result, there is a drawback that various properties such as heat resistance, which is an important property of the cured product, deteriorate.

[0006] Therefore, an object of the present invention is to provide a powder coating comprising a thermosetting composition capable of forming a cured product having high flame retardancy while suppressing a decrease in fluidity during melting, and an electric and electronic component provided with a sealing portion composed of the cured product of the coating.

Means for Solving the Problems

[0007] The present inventors have found that the above problems can be solved by using a plurality of specific organic flame retardants in combination, combining these with a specific flame retardant aid, and adjusting their blending ratios, and have completed the present invention.

[0008] That is, according to the present invention, a powder coating having the following configuration is provided. Further, according to the present invention, an electric and electronic component in which at least a part of an element is sealed with a sealing portion composed of a cured product obtained by thermally curing the powder coating having the following configuration is also provided.

[0009] Hereinafter, (A): a thermosetting compound, (B): a curing agent that reacts with (A), (C): an organic flame retardant, (C1): a phosphate-containing compound, (C2): a phosphinate-containing compound, (C3): a phosphorus compound compatible with the mixture of (A) and (B), (D): a flame retardant aid, (D1): yellow iron oxide, are used. Also, (C1a): a specific melamine salt selected from melamine orthophosphate, melamine pyrophosphate, and melamine polyphosphate, (C1b): a specific piperazine salt selected from piperazine orthophosphate, piperazine pyrophosphate, and piperazine polyphosphate, are used.

[0010] At this time, the powder coating according to the present invention is a coating for forming a cured product having flame retardancy conforming to the UL94V-0 standard, which is composed of a finely pulverized product of a thermosetting composition, the thermosetting composition contains (A), (B), (C) and (D), (C) contains 90% by mass or more of (C1) and (C2), but does not contain (C3), the mass ratio of (C2) to (C1) is 0.2 or more and 0.8 or less, (D) contains 90% by mass or more of (D1), and the mass ratio of (C2) to (D1) is 0.5 or more and 1.5 or less, which is characterized in that.

[0011] The above powder coating may include the following aspects. (C1) may contain a mixture of (C1a) and (C1b). The mass ratio of (C1b) to (C1) can be 1 or more and 4 or less. (C2) may contain an aluminum salt of an organic phosphinic acid. The size of (C1) can be 1 μm or more and 10 μm or less in terms of mass average particle diameter. The size of (C2) can be 5 μm or more and 30 μm or less in terms of mass average particle diameter. The size of (D1) can have a major axis of 0.3 μm or more and 1.0 μm or less, and a minor axis of 0.05 μm or more and 0.6 μm or less. (C) may be contained in the range of 10 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of (A). (D) may be contained in the range of 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of (A). The phosphorus atom content can be 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the organic components other than (C) and (C). [Advantages of the Invention]

[0012] According to the present invention, a plurality of specific organic flame retardants are used in combination, and in combination with a specific flame retardant aid, and their blending ratios are adjusted. Therefore, while suppressing a decrease in fluidity during melting, a cured product having high flame retardancy can be formed. There is provided a powder coating comprising a thermosetting composition, and an electric or electronic component provided with a coating film composed of a cured product of the coating.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the best mode for carrying out the present invention will be described. However, the present invention is not limited to the following embodiments, and within the scope not departing from the gist of the present invention, based on the ordinary knowledge of those skilled in the art, the following embodiments may be appropriately modified, improved, etc., and are also within the scope of the present invention.

[0014] The powder coating according to one embodiment of the present invention is a coating for forming a cured product having flame retardancy conforming to the UL94V-0 standard (in one embodiment, having V-0 flame retardancy by the UL94 vertical burning test at a thickness of 0.5 mm), and is composed of a fine pulverized product of a thermosetting composition. A thermosetting composition (hereinafter simply abbreviated as "composition") according to one embodiment for forming a powder coating contains (A) a thermosetting compound, (B) a curing agent that reacts with (A), (C) an organic flame retardant, and (D) a flame retardant aid. (C) used for forming the composition contains (C1) a phosphate-containing compound and (C2) a phosphinate-containing compound, and may contain components other than (C1) and (C2). However, from the viewpoint of suppressing a decrease in heat resistance performance, (C) does not contain (C3) a phosphorus compound compatible with the mixture of (A) and (B). (D) used for forming the composition contains (D1) yellow iron oxide, and may contain components other than (D1). That is, the powder coating according to one embodiment of the present invention is composed of a fine pulverized product of a composition containing (A), (B), (C1), (C2), and (D1) and not containing (C3). Hereinafter, the details of the powder coating according to one embodiment of the present invention will be described.

[0015] <(A)> (A) used for forming the composition is not particularly limited as long as it is a thermosetting compound used as a raw material in the production of powder coatings. For example, epoxy compounds such as epoxy resins, phenolic resins, and benzoxazine compounds can be mentioned. Among these, as (A), epoxy compounds are preferred. The epoxy compound is not particularly limited as long as it is an epoxy compound used as a raw material in the production of powder coatings. For example, bisphenol-type epoxy compounds (e.g., bisphenol A-type epoxy compounds, bisphenol F-type epoxy compounds, brominated bisphenol A-type epoxy compounds, hydrogenated bisphenol A, and AD-type epoxy compounds, etc.), phenol novolak-type epoxy compounds, dicyclopentadiene-type epoxy compounds, cresol novolak-type epoxy compounds, bisphenol A novolak-type epoxy compounds, and naphthalene ring-containing epoxy compounds can be mentioned. As the epoxy compound, epoxy resins which are polymers of the above-mentioned various epoxy compounds are also included. Among these, as the epoxy compound, preferably, bisphenol-type epoxy resins such as bisphenol A-type epoxy resins are used.

[0016] The epoxy compound preferably has an epoxy equivalent of 600 g / eq or more and 850 g / eq or less. By setting the epoxy equivalent of the epoxy compound within the above range, the crosslink density of the cured product becomes high and the flame retardancy becomes good. Specifically, by setting the epoxy equivalent to 600 g / eq or more, the expected flame retardancy can be maintained without a decrease in the crosslink density, and by setting it to 850 g / eq or less, a stable carbonized layer (also called char) is formed and the flame retardancy is improved. The epoxy compound may be used in combination of two or more types having different epoxy equivalents so that the epoxy equivalent is in the range of 600 g / eq or more and 850 g / eq or less.

[0017] The physical properties of the epoxy compound are not particularly limited, but considering the curability, preferably, the softening point is 80°C or higher and 120°C or lower. By setting the softening point of the epoxy compound within the above range, the smoothness of the cured product becomes good. The epoxy compound may be used by combining two or more types having different softening points so that the softening point is in the range of 80°C or higher and 120°C or lower. The softening point can be measured by the ring and ball method of JIS K 7234.

[0018] (A) may be used alone or in combination of two or more.

[0019] <(B)> (B) used for forming the composition is not particularly limited as long as it is a curing agent that reacts with (A). (B) varies depending on the type of (A) used. Examples of (B) when an epoxy compound is used as (A) include phenolic curing agents, diamine curing agents, acid anhydride curing agents, and cyanate curing agents. Examples of phenolic curing agents include phenolic novolak resins, phenol aralkyl resins, bisphenol A novolak resins, cresol novolak resins, and naphthol aralkyl resins. Examples of diamine curing agents include diethyldiaminodiphenylmethane and dicyandiamide (DICY). Examples of acid anhydride curing agents include alicyclic acid anhydrides (e.g., hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA)), aromatic acid anhydrides (e.g., trimellitic anhydride (TMA) and pyromellitic anhydride (PMDA)), and benzophenone tetracarboxylic acid (BTDA). Examples of cyanate curing agents include bisphenol A type cyanate ester resins. (B) may be used alone or in combination of two or more.

[0020] The equivalent ratio of (B) to (A) is preferably 0.3 or more, more preferably 0.5 or more, preferably 2 or less, more preferably 1.5 or less. That is, the respective contents of (A) and (B) are preferably contents that satisfy the above equivalent ratio range. If the respective contents of (A) and (B) are contents that satisfy the above equivalent ratio range, a thermosetting composition having more excellent heat resistance and flame retardancy of the cured product is obtained. This is considered to be because the curing reactions of (A) and (B) proceed suitably.

[0021] <(C)> It is essential that (C) used for forming the composition is a combination of a plurality of halogen-free organic flame retardants. In particular, as (C), at least (C1) a phosphate-containing compound and (C2) a phosphinate-containing compound are used in combination. In one embodiment, the reason for using (C) as a combination of these rather than each single substance of (C1) or (C2) is as follows. When (C) is composed of (C1) alone, the flame retardancy of the cured product is significantly reduced, so (C2) is used in combination therewith. In particular, by using (C1) and (C2) in combination at a predetermined mass ratio described later, a synergistic flame retardant effect can be expected.

[0022] <(C1)> Examples of (C1) used as part of (C) include salts obtained by reacting a phosphate compound with an amine compound having at least one amino group in the molecule. (C1) may be used alone or in combination of two or more. A compound or mixture containing a phosphorus component that promotes carbonization and a nitrogen component that promotes fire extinguishing and foaming functions as an intumescent flame retardant and is preferably used because of its high flame retardancy.

[0023] Examples of the phosphoric acid compound include monophosphoric acids such as orthophosphoric acid, polyphosphoric acids such as pyrophosphoric acid and tripolyphosphoric acid. Among these phosphoric acid compounds, polyphosphoric acid is preferably included. That is, (C1) preferably contains a polyphosphate. In this case, higher flame retardancy can be obtained compared to the case where (C1) does not contain polyphosphoric acid.

[0024] Examples of the amine compound include aliphatic diamines such as N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, 1,2-propanediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, and 1,10-diaminodecane; amine compounds containing a piperazine ring such as piperazine, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, and 1,4-bis(3-aminopropyl)piperazine; amine compounds containing a triazine ring such as melamine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1,3,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-mercapto-1,3,5-triazine, and 2-amino-4,6-dimercapto-1,3,5-triazine.

[0025] (C1) preferably contains at least one compound selected from melamine salts (such as melamine orthophosphate salt, melamine pyrophosphate salt, and melamine polyphosphate salt, etc.) and piperazine salts (such as piperazine orthophosphate salt, piperazine pyrophosphate salt, and piperazine polyphosphate salt, etc.). Among them, (C1) preferably contains a specific melamine salt (C1a) selected from melamine orthophosphate salt, melamine pyrophosphate salt, and melamine polyphosphate salt, and a specific piperazine salt (C1b) selected from piperazine orthophosphate salt, piperazine pyrophosphate salt, and piperazine polyphosphate salt. In this case, the mass ratio of (C1a) to (C1b) is such that in the mixture, for (C1a):1, (C1b) is preferably 1 or more, more preferably 2 or more, preferably 4 or less, more preferably 3 or less. Within this mass ratio range, by mixing and using (C1a) and (C1b), not only the flame retardancy is improved, but also the effect of suppressing the components from oozing out to the surface is easily obtained.

[0026] Among them, from the perspective of flame retardancy, (C1a) is preferably melamine pyrophosphate salt. When (C1a) is used in a mixture, the higher the content ratio of melamine pyrophosphate salt, the more preferable. Also, the ratio of pyrophosphate to melamine in melamine pyrophosphate salt is preferably 1:1.5 to 1:2.5 in molar ratio, and more preferably 1:2. These salts of phosphoric acid and melamine can also be obtained by reacting the corresponding phosphoric acid or phosphate with melamine. However, as (C1a), melamine pyrophosphate salt or melamine polyphosphate salt obtained by heat condensation of melamine orthophosphate salt is preferred, and melamine pyrophosphate salt is particularly preferred.

[0027] Among them, from the perspective of flame retardancy, (C1b) is preferably piperazine pyrophosphate salt. When (C1b) is used in a mixture, the higher the content ratio of piperazine pyrophosphate salt, the more preferable. Also, the ratio of pyrophosphate to piperazine in piperazine pyrophosphate salt is preferably 1:0.5 to 1:1.5 in molar ratio, and more preferably 1:1. These salts of phosphoric acid and piperazine can also be obtained by reacting the corresponding phosphoric acid or phosphate with piperazine. However, as (C1b), a piperazine pyrophosphate salt or a piperazine polyphosphate salt obtained by heat-condensing a 2-orthophosphoric acid 1-piperazine salt is preferred, and a piperazine pyrophosphate salt is particularly preferred.

[0028] The size of (C1) is the mass average particle diameter, preferably 1 μm or more, more preferably 5 μm or more, preferably 10 μm or less, and more preferably 7 μm.

[0029] As (C1), commercially available products may be used. For example, those manufactured by ADEKA CORPORATION, trade name: ADEKA STAB series (e.g., FP2000, FP2100, and FP2200) etc. can be mentioned.

[0030] <(C2)> Examples of (C2) used in a part of (C) include aluminum dialkylphosphonate, aluminum tris(diethylphosphonate), aluminum tris(methylethylphosphonate), aluminum tris(diphenylphosphonate), zinc bis(diethylphosphonate), zinc bis(methylethylphosphonate), zinc bis(diphenylphosphonate), titanyl bis(diethylphosphonate), titanium tetrakis(diethylphosphonate), titanyl bis(methylethylphosphonate), titanium tetrakis(methylethylphosphonate), titanyl bis(diphenylphosphonate), and titanium tetrakis(diphenylphosphonate). Among them, (C2) preferably contains an aluminum salt (e.g., aluminum dialkylphosphonate, aluminum tris(diethylphosphonate), aluminum tris(methylethylphosphonate), and aluminum tris(diphenylphosphonate) etc.). (C2) may be used alone or in combination of two or more. The size of (C2) is the mass average particle diameter, preferably 5 μm or more, more preferably 10 μm or more, preferably 30 μm or less, and more preferably 20 μm.

[0031] (C2) may be a commercially available product. For example, products manufactured by Clariant Japan K.K., trade name: EXOLIT OP series (e.g., OP1230, OP1240, OP1312, OP1400, OP930, OP935, and OP945) etc. can be mentioned.

[0032] (C1) and (C2) are both incompatible (non - miscible) with the mixture of (A) and (B). By "incompatible (non - miscible)" it means that (C1) and (C2) are in a state of being dispersed in an island - like manner in the mixture of (A) and (B). That is, the composition constituting the powder coating according to one embodiment of the present invention, as (C), by using (C1) and (C2) together, which are incompatible with the mixture of (A) and (B), can be expected to form a tougher carbonized layer compared to the case of containing a phosphorus compound that is miscible with the mixture of (A) and (B), that is, (C3).

[0033] The mass ratio of (C2) in (C) is preferably 0.2 or more, more preferably 0.5 or more, preferably 0.8 or less, more preferably 0.4 or less, with respect to (C1):1. By using (C1) and (C2) together within this mass ratio range, the merit of a synergistic flame - retardant effect is easily obtained. If the proportion of (C1) is too large (the proportion of (C2) is too small), there is a tendency for the toughness of the formed carbonized layer to decrease. On the other hand, if the proportion of (C1) is too small (the proportion of (C2) is too large), there is a tendency for the fluidity of the powder coating to decrease during heat - melting.

[0034] The total content of (C1) and (C2) in (C) is preferably 90% by mass or more, more preferably 95% by mass or more. Its upper limit is not particularly limited and is 100% by mass.

[0035] (C) used for forming the composition may consist of (C1) and (C2), or may further contain other organic flame retardants different from these two types. However, from the viewpoint of suppressing the deterioration of heat resistance, other organic flame retardants do not contain (C3) a phosphorus compound compatible with the mixture of (A) and (B). That is, (C) according to one form contains at least (C1) and (C2), but does not contain (C3).

[0036] <(C3)> Compatibility means being in a state of being finely dispersed at the molecular level in the mixture of (A) and (B). Examples of (C3) include phosphate ester compounds, phosphazene compounds, phosphite ester compounds, and phosphine compounds. Examples of phosphate ester compounds include triphenyl phosphate, tricresyl phosphate, xylenyl diphenyl phosphate, cresyl diphenyl phosphate, 1,3-phenylene bis(di-2,6-xylenyl phosphate), 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), condensed phosphate ester compounds such as aromatic condensed phosphate ester compounds, and cyclic phosphate ester compounds. Examples of phosphazene compounds include cyclic or chain phosphazene compounds. Cyclic phosphazene compounds, also called cyclophosphazenes, are compounds having a double bond composed of phosphorus and nitrogen as constituent elements in the molecule and having a cyclic structure. Examples of phosphite ester compounds include trimethyl phosphite and triethyl phosphite. Examples of phosphine compounds include tris-(4-methoxyphenyl)phosphine and triphenylphosphine.

[0037] In one embodiment, the content of (C) in the composition is, for example, 10 parts by mass or more, preferably 15 parts by mass or more, and for example, 25 parts by mass or less, preferably 20 parts by mass or less, relative to 100 parts by mass of (A). If the content of (C) is too low, the flame retardant effect cannot be expected. On the other hand, if the content of (C) is too high, not only does the degree of manifestation of the flame retardant effect not change, but the blending ratio of other components relatively decreases, and as a result, it is likely to be accompanied by a decrease in various properties (such as heat resistance) that the cured product should originally have, which is not preferable.

[0038] The composition constituting the powder coating preferably has a phosphorus atom content of 1 part by mass or more, more preferably 2 parts by mass or more, preferably 5 parts by mass or less, and more preferably 4 parts by mass or less, relative to a total of 100 parts by mass of the organic components other than (C) and (C). That is, the content of (C) is preferably such that the phosphorus atom content in the composition constituting the powder coating is within the above range (for example, in the range of 10 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of (A) as described above). With such a content, a flame retardant effect is easily obtained. The organic components other than (C) include organic components such as (A) and (B), and when additional organic components are added, it means including these additionally added organic components.

[0039] <(D)> (D) used for forming the composition is a particle component that assists the function of (C), and when used in combination with (C), a dramatic improvement in the flame retardant effect is expected. (D) according to one embodiment includes (D1) yellow iron oxide.

[0040] <(D1)> (D1), which is used in part of (D), is a hydroxide represented by FeOOH or Fe2O3·H2O and occurs in nature as the mineral goethite. It is also called iron oxyhydroxide or ocher and has the characteristic that water of crystallization is relatively easily removed at around 180 °C to change to Fe2O3. When (D1) is blended into the composition together with (C2), it has been found that the flame retardant effect of the cured coating film of the powder coating composed of the finely pulverized product of the composition is remarkably improved. The mechanism by which the flame retardant effect is remarkably improved is not clear, but it is presumed that (D1) acts as an accelerator during the formation of the carbonized layer, and as a result, the formed carbonized layer becomes tough and the heat insulation property is improved. Thus, even if the phosphorus atom content in the composition constituting the powder coating is low (3 mass% or less), it is considered that the powder coating can exhibit a high flame retardant effect. The size of (D1) is, for example, the major axis is 0.3 μm or more and 1.0 μm or less, and the minor axis is 0.05 μm or more and 0.6 μm or less. The mass ratio of (D1) in (D) is preferably 0.5 or more, more preferably 1 or more, preferably 2 or less, and more preferably 1.6 or less with respect to (C2) contained in (C):1. Within this mass ratio range, by blending (D1), the formation of the carbonized layer is promoted and the merit of improving the flame retardant effect is easily obtained. If the proportion of (C2) is too large (the proportion of (D1) is too small), the demerit of reducing the flame retardant effect is likely to occur. On the other hand, if the proportion of (C2) is too small (the proportion of (D1) is too large), not only the flame retardant effect is reduced, but also the demerit of poor appearance is likely to occur.

[0041] The content of (D1) in (D) is preferably 90 mass% or more, more preferably 95 mass% or more. The upper limit is not particularly limited and is 100 mass%.

[0042] (D) used for forming the composition may consist only of (D1) or may further contain other inorganic compounds different from this. Examples of other inorganic compounds include titanium oxide, silica, aluminum hydroxide, magnesium hydroxide, and alumina.

[0043] In one embodiment, the content of (D) in the composition is, for example, 2 parts by mass or more, preferably 4 parts by mass or more, and for example, 10 parts by mass or less, preferably 8 parts by mass or less, based on 100 parts by mass of (A). If the content of (D) is too low, the flame retardant effect cannot be expected. On the other hand, if the content of (D) is too high, it is likely to cause inconvenience such as poor appearance, which is not preferable.

[0044] <Auxiliary components> In the composition constituting the powder coating, auxiliary components other than the above components ((A), (B), (C) and (D)) can be appropriately blended as necessary, as long as the effects of the invention are not impaired. Examples of the auxiliary components include fillers other than (D), additives, and the like.

[0045] Examples of the filler include inorganic pigments and extender pigments. The inorganic pigment is not particularly limited, and examples include metal oxides (excluding (D1)), sulfides or sulfates. For example, titanium oxide, zinc white, red iron oxide, lead yellow, ultramarine blue, carbon black, graphite, etc. are exemplified, but not limited thereto. Examples of the extender pigment include calcium carbonate, barium sulfate, kaolin, alumina, silica, talc, mica, zinc phosphate, and clay, etc., but not limited thereto. The filler may be used alone or in combination of two or more. The filler may be used as it is, or may be surface-treated with a silane coupling agent of the epoxy silane type or the amino silane type. When the filler is contained, its content is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, based on 100 parts by mass in total of the organic components excluding (C) and (C).

[0046] Examples of the additives include defoamers, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes, lubricants, and dispersants such as wetting dispersants. The additives may be used alone or in combination of two or more. When the additives are contained, the content thereof is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, preferably 10 parts by mass or less, and more preferably 6 parts by mass or less with respect to 100 parts by mass in total of the organic components excluding (C) and (C).

[0047] The powder coating according to one embodiment of the present invention can be produced, for example, by the following method. First, the compounding components are mixed using a mixer or the like, and then melt-kneading or the like is performed using an extruder. The mixing temperature and mixing time are not particularly limited and are set according to the type of raw materials, composition ratio, and the like. Usually, the mixing temperature is preferably 90 to 130°C. Thereafter, the obtained mixture is cooled and solidified, and the solidified mixture (melt-kneaded product) is finely pulverized and classified to obtain a powder coating.

[0048] The powder coating according to one embodiment of the present invention contains at least (A), (B), (C), and (D). Depending on the mixing conditions, partial polymerization proceeds and contains a polymer containing a structural unit derived from (A).

[0049] (i) Volume average particle diameter The particle diameter of the powder coating according to one embodiment is not particularly limited, but the volume average particle diameter measured by the laser diffraction / scattering method (JIS Z8825) is, for example, 10 μm or more, preferably 15 μm or more, for example, 80 μm or less, and preferably 50 μm or less. The above volume average particle diameter can be measured using a laser diffraction particle size distribution measuring device (manufactured by SYMPATEC, HELOS and PRODOS analysis software: WINDOX5). By using a powder coating having a volume average particle diameter within the above range, more excellent film-forming properties can be obtained.

[0050] (ii) Horizontal flow rate The powder coating according to one embodiment has a horizontal flow rate of, for example, 2% or more, preferably 2.5% or more, more preferably 3% or more, and, for example, 10% or less, preferably 6% or less. If the horizontal flow rate of the coating is too small, the coating will not flow during melting, so coating film defects such as pinholes are likely to occur, and a smooth coating film cannot be obtained. If the horizontal flow rate of the coating is too large, a phenomenon called sagging occurs during the process from melting to curing when obtaining a cured coating film, and it becomes impossible to form a desired film thickness. Note that the horizontal flow rate indicates the meltability during heating of the powder coating. A large value indicates that the coating is likely to flow because it has a low viscosity during melting, and a small value indicates that the coating is unlikely to flow because it has a high viscosity during melting. The method for measuring the horizontal flow rate will be described later.

[0051] (iii) Gelation time (curability) The powder coating according to one embodiment has a curability such that the time until gelation at 160 °C in accordance with JIS C 2104 is, for example, 50 seconds or more, preferably 80 seconds or more. If the gelation time is 80 seconds or more, not only can a cured product sufficient to exhibit desired properties be obtained, but it can also be said that the meltability during heating is excellent. If the gelation time is too long, the horizontal flow rate of the coating becomes too large, and the viscosity becomes low during melting, making the coating likely to flow. As a result, coating film defects such as pinholes and sagging may easily occur. From the viewpoint of maintaining the horizontal flow rate of the coating at, for example, 10% or less, the gelation time of the powder coating is preferably 130 seconds or less.

[0052] The coating method of the powder coating according to one embodiment is not particularly limited, and known coating methods can be applied. Specifically, electrostatic coating, triboelectric coating, non-charged coating, dip coating, etc. are mentioned. Among these, from the viewpoint of uniform coating, the electrostatic coating method is preferable. By the above method, after coating the surface of the object to be coated (for example, electrical and electronic component elements) with the powder coating, the surface of the object to be coated is coated with a cured product (coating layer) of the powder coating by curing. If necessary, the surface of the object to be coated can be pre-treated to improve the adhesion of the cured product.

[0053] As the electric and electronic components, although not particularly limited, for example, tantalum capacitors can be mentioned. The tantalum capacitor to which the powder coating according to one embodiment can be applied is not limited as long as it is a known solid tantalum capacitor encapsulated and exteriorized with resin. The tantalum capacitor according to one embodiment includes a capacitor element (an example of an object to be coated) and a sealing portion (an example of a coating layer) that encapsulates and seals the element, and the sealing portion is formed of a cured product of the powder coating according to one embodiment of the present invention. The capacitor element includes, for example, an anode body (element body) formed by pressure molding and sintering tantalum powder, and a dielectric layer composed of an oxide film layer formed by anodizing the surface thereof. As a counter electrode outside the element body, for example, a semiconductor layer such as a manganese dioxide layer and a cathode layer are provided around it with silver paste or the like, and this cathode layer is connected to an external cathode lead via a conductive adhesive or the like. The extraction on the anode side is performed by a tantalum lead wire embedded in the element body in advance and an external anode lead connected thereto. The capacitor element having such a structure (an example) is exteriorized by a sealing portion. The thickness of the sealing portion is, for example, 30 μm or more, preferably 50 μm or more, for example, 120 μm or less, preferably 100 μm or less. The tantalum capacitor according to one embodiment is not particularly limited as long as the surface of the tantalum sintered body (anode body) is oxidized to function as a dielectric layer and is encapsulated and exteriorized with resin, and includes various modified and improved ones. The shape is not limited to the surface mount type chip capacitor described above.

Examples

[0054] Hereinafter, the present invention will be specifically described based on experimental examples (including examples and comparative examples), but the present invention is not limited to these experimental examples. In the following description, "parts" indicates "parts by mass", and "%" indicates "% by mass".

[0055] [Constituent Components of Powder Coating] The following were prepared as A (thermosetting compound). ·A1: Bisphenol A type (solid) epoxy resin with an epoxy equivalent of 630 g / eq (GESR902, Epoxy Base Electronic Material Corporation Limited (CN)) ·A2: Bisphenol A type (solid) epoxy resin with an epoxy equivalent of 810 g / eq (GESR904, Epoxy Base Electronic Material Corporation Limited (CN))

[0056] Note that the epoxy equivalent of the whole of A is a value (about 652) calculated with the value (0.1534) obtained by adding all the values (0.1349 for A1 and 0.0185 for A2) obtained by dividing the content of each component (85 parts by mass for A1 and 15 parts by mass for A2) when the whole is 100 parts by mass by the epoxy equivalent of each component (630 g / eq for A1 and 810 g / eq for A2) as the denominator and the mass of the whole of A (100) as the numerator.

[0057] As B (a curing agent that reacts with A), the following were prepared. ·B1: Aromatic tetracarboxylic dianhydride (Anhydride-based curing agent, BTDA-PF, Evonik Japan K.K., content of 3,3’,4,4’-benzophenone tetracarboxylic dianhydride is 98%) ·B2: Dicyandiamide (Solid dispersion type amine-based curing agent, jER Cure DICY20, Mitsubishi Chemical Corporation)

[0058] As C (an organic flame retardant), the following were prepared. ·C1: A compound containing an amine phosphate salt (phosphorus concentration 19% by mass) (Adekastab FP2200, ADEKA Corporation) ·C2: An aluminum salt compound of an organic phosphinic acid (phosphorus concentration 23% by mass) (Exolit OP1230, Clariant Japan K.K.) ·C3: An aromatic condensed phosphate ester compound (phosphorus concentration 9% by mass) (PX200, Daihachi Chemical Industry Co., Ltd.)

[0059] Incidentally, Adeka Stab FP2200 of C1 is an approximately 95 / 5 (mass ratio) mixture of a phosphate amine salt with a dimelamine pyrophosphate component / piperazine pyrophosphate component = approximately 40 / 60 (mass ratio) and zinc oxide. C1 and C2 are immiscible (non-compatible) with the mixture of A and B, but C3 is compatible.

[0060] The following were prepared as D (flame retardant aid). · D1: Yellow iron oxide (FeOOH, major axis 0.51 μm, minor axis 0.48 μm) (Biferox 915, Lanxess Co., Ltd.)

[0061] Incidentally, the size (major axis, minor axis) of Biferox 915 of D1 is the value measured using a transmission electron microscope before mixing described later.

[0062] The following were prepared as E (auxiliary component). · E1: Titanium oxide (Typecoat R-830, Ishihara Sangyo Co., Ltd.) · E2: Red iron oxide (Toda Color 335R, Toda Kogyo Co., Ltd.) · E3: Alumina (average primary particle diameter 13 nm) (AEROXIDE Alu C, Nippon Aerosil Co., Ltd.)

[0063] 1. Preparation of powder coating [Experimental Examples 1 to 10] All the materials for each experimental example were mixed at the mixing ratios (mass) shown in Table 1, and then kneaded by an extruder to obtain a kneaded product. After cooling and solidifying the obtained kneaded product, it was finely pulverized to obtain a powder coating.

[0064] 2. Evaluation For the powder coatings obtained in each experimental example, the paintability and curability were evaluated by the methods shown below. Also, for the cured products (thermosetting coatings) of the powder coatings obtained in each experimental example, the flame retardancy was evaluated by the methods shown below. The results are shown in Table 1.

[0065] (2-1) Paintability The paintability of the powder coating was evaluated by measuring the horizontal flow rate. Approximately 1.0 g of the powder coating obtained in each experimental example was placed in a die for tablet forming with an inner diameter of 1.6 mm φ, pressed at a load of 83 - 92 MPa for 60 seconds to form a tablet, then dried in a desiccator under a reduced pressure of 1333 Pa or less for 15 minutes, and the diameter (a) of the tablet was measured with calipers. Next, the obtained tablet was placed on a slide glass, heated in a hot air dryer at 140 °C for 10 minutes and then taken out, and the diameter (b) of the tablet was measured in the same manner. Then, the increase value of the diameter due to heating (b - a) was divided by the diameter (a) before heating, and then multiplied by 100 to calculate the horizontal flow rate for each powder coating obtained in each experimental example. The evaluation criteria are as follows.

[0066] 〇: The horizontal flow rate is 2% or more and 10% or less ×: The horizontal flow rate is less than 2% or more than 10%

[0067] (2-2) Curability The curability of the powder coating was evaluated by measuring the gelation time. Approximately 0.05 g of the powder coating obtained in each experimental example was placed in the circular recess of a hot plate maintained at 160 °C, stirred with a stirring rod, and the time until the thread could no longer be drawn, that is, the time until gelation (seconds) was measured. The measurement was carried out in accordance with JIS C 2104. The evaluation criteria are as follows.

[0068] ○: The gelation time is 80 seconds or more and 130 seconds or less ×: The gelation time is less than 80 seconds or more than 130 seconds

[0069] (2-3) Flame retardancy The flame retardancy of the cured product was evaluated by conducting a vertical combustion test according to UL94 (a standard defined by Underwriters Laboratories Inc. in the United States). The powder coatings obtained in each experimental example were heated and cured at 150 °C for about 60 minutes using a hot press machine (manufactured by Daisin Machine) to form test pieces for combustion (length 127 mm × width 12.7 mm × thickness 0.5 mm) composed of the cured products of the powder coatings. Five test pieces were prepared for each sample, and tests were conducted in accordance with the vertical combustion test method of UL94. If the test results did not meet the V-2 standard, it was considered non-compliant.

[0070] The evaluation criteria for the flame retardancy of each test piece are as follows. ○: Complies with the UL94 V-0 standard ×: Does not comply with the UL94 V-0 standard

[0071]

Table 1

[0072] 3. Discussion As shown in Table 1, when both (C1) and (C2) were not included as (C) in the paint (Experimental Example 10), the flame retardancy of the paint film could not be satisfied. On the other hand, even when both (C1) and (C2) were included (Experimental Examples 1 to 9), if the mass ratio of (C2) to (C1) was less than 0.2 (Experimental Example 1) or more than 0.8 (Experimental Example 5), one or more of the paintability (horizontal flow rate) and flame retardancy of the paint could not be satisfied. When (D1) was not included as (D) in the paint (Experimental Example 10), and even when (D1) was included (Experimental Examples 1 to 9), if the mass ratio of (D1) to (C2) was less than 0.5 (Experimental Example 6) or more than 1.5 (Experimental Examples 1 and 9), in both cases, the flame retardancy could not be satisfied. On the other hand, when the mass ratio of (C2) to (C1) is 0.2 or more and 0.8 or less, and the mass ratio of (D1) to (C2) is 0.5 or more and 1.5 or less (Experimental Examples 2 to 4, 7, and 8), all of the paint application properties, curability, and flame retardancy could be satisfied.

Claims

1. A powder coating for forming a cured product having flame retardancy conforming to the UL94V-0 standard, which is composed of a pulverized product of a thermosetting composition, the thermosetting composition contains (A), (B), (C) and (D), (C) contains 90% by mass or more of (C1) and (C2), but does not contain (C3), (C1): The mass ratio of (C2) to 1 is 0.2 or more and 0.8 or less, (D) contains 90% by mass or more of (D1), and the mass ratio of (C2) to (D1) to 1 is 0.5 or more and 1.5 or less. The powder coating. (A) Epoxy resin (B) A curing agent that reacts with (A) (C) Organic flame retardant (C1) Phosphate-containing compound (C2) Phosphinate-containing compound (C3) A phosphorus compound compatible with the mixture of (A) and (B) (D) Flame retardant aid (D1) Yellow iron oxide

2. The powder coating according to claim 1, wherein (C1) contains a mixture of (C1a) and (C1b). (C1a) Specific melamine salts selected from melamine orthophosphate salt, melamine pyrophosphate salt, and melamine polyphosphate salt (C1b) Specific piperazine salts selected from piperazine orthophosphate salt, piperazine pyrophosphate salt, and piperazine polyphosphate salt

3. The powder coating according to claim 1 or 2, wherein the mass ratio of (C1a) to (C1b) to 1 is 1 or more and 4 or less.

4. The powder coating according to any one of claims 1 to 3, wherein (C2) contains an aluminum salt of an organic phosphinic acid.

5. The powder coating according to any one of claims 1 to 4, wherein the size of (C1) is 1 μm or more and 10 μm or less in terms of mass average particle diameter.

6. The size of (C2) is a mass average particle diameter, which is 5 μm or more and 30 μm or less. The powder coating according to any one of claims 1 to 5.

7. The size of (D1) is such that the major axis is 0.3 μm or more and 1.0 μm or less, and the minor axis is 0.05 μm or more and 0.6 μm or less. The powder coating according to any one of claims 1 to 6.

8. (C) is contained in a range of 10 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of (A). The powder coating according to any one of claims 1 to 7.

9. (D) is contained in a range of 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of (A). The powder coating according to any one of claims 1 to 8.

10. The phosphorus atom content is 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the organic components other than (C) and (C). The powder coating according to any one of claims 1 to 9.

11. An electric / electronic component in which at least a part of an element is sealed with a sealing portion composed of a cured product of the powder coating according to any one of claims 1 to 10.

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