JP2012255139A - Flame-retardant epoxy resin powder coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant epoxy resin powder coating that has excellent flame retardance even if a halogenated flame retardant is not used and that is improved in mechanical strength.SOLUTION: The flame-retardant epoxy resin powder coating comprises an epoxy resin, a curing agent, a filler, a laser color former, and an ester phosphate-based flame retardant, wherein a thermal expansion coefficient equal to or larger than a glass transition temperature of the epoxy resin powder coating is 10×10/°C or lower.

Description

  The present invention relates to an epoxy resin powder coating.

  Epoxy resin powder coatings are conventionally used for the purpose of insulating and covering electrical and electronic parts. Such an epoxy resin powder coating is also required to have a high degree of flame retardancy in the insulating exterior coating film in order to ensure the safety of electrical and electronic parts against fire. For this reason, various compounds that impart flame retardancy are blended in the components of the powder coating.

  As a method for imparting flame retardancy, for example, a flame retardant resin component is reduced and a non-flammable inorganic filler, particularly crystallization water is contained and released at the time of combustion so as to exhibit a flame retardant effect. Various methods have been proposed and implemented, such as a method of blending a large amount of inorganic fillers such as aluminum hydroxide and magnesium hydroxide, and a method of modifying an epoxy resin with a low-flammability silicone resin or a cyanurate ring-containing resin. However, the most widely practiced method is to blend various halogen-based flame retardants (for example, Patent Document 1).

JP-A-6-57101

  The present invention has been made in view of such circumstances, and provides an epoxy resin powder coating having excellent flame retardancy and improved mechanical strength without using a halogen-based flame retardant. Is.

  The present inventors have found that the mechanical strength of the epoxy resin powder coating depends on the coefficient of thermal expansion equal to or higher than the glass transition temperature (Tg) of the epoxy resin powder coating, leading to the present invention.

According to the present invention for solving the above problems, an epoxy resin powder coating containing an epoxy resin, a curing agent, a filler, a laser color former, and a phosphate ester flame retardant,
There is provided a flame retardant epoxy resin powder coating material having a thermal expansion coefficient of 10 × 10 ⁻⁵ / ° C. or less of Tg or more of the epoxy resin powder coating material.

  In one Embodiment of this invention, the said filler is 50 mass% or more with respect to the mass of the said epoxy resin powder coating material.

  In one embodiment of the present invention, the laser color former includes a copper compound or a zirconium compound.

  In one embodiment of the invention, the filler is fused silica.

  In one embodiment of the present invention, the curing agent includes an acid anhydride.

In one Embodiment of this invention, the bending elastic modulus of the said epoxy resin powder coating material is 1.0 * 10 < ⁴ > MPa or more.

  In one Embodiment of this invention, the glass transition temperature of the said epoxy resin powder coating material is 100 degrees C or less.

  In one embodiment of the present invention, the epoxy resin powder coating is used for an exterior coating film of an electric / electronic component.

  ADVANTAGE OF THE INVENTION According to this invention, while having the flame retardance which was excellent even if it did not use a halogenated flame retardant, the epoxy resin powder coating material with improved mechanical strength is provided.

  The flame retardant epoxy resin powder coating of the present invention will be described below. In addition, unless otherwise specified, “to” represents the following.

The flame-retardant epoxy resin powder coating of the present invention contains an epoxy resin, a curing agent, a filler, a laser color former, and a phosphate ester flame retardant, and has a thermal expansion coefficient of 10 × 10 ⁻⁵ or more than Tg. / ° C or less. Here, said Tg represents the glass transition temperature by the thermomechanical analysis (TMA) method measured based on JISC2161.

  The epoxy resin used in the present invention has at least one epoxy group in the molecule, is a non-halogenated epoxy resin, and is solid at room temperature applied to general epoxy resin powder coatings. Can be used if present. Examples of such epoxy resins include, but are not limited to, bisphenol A type, bisphenol F type, bisphenol S type, phenol novolac type, cresol novolac type, biphenyl type, naphthalene type, and aromatic amine type. It is not something. These may be used alone or in combination.

  As the curing agent used in the present invention, various types of curing agents can be used alone or in combination depending on the purpose to which the epoxy resin powder coating is applied. For example, aromatic amines such as diaminodiphenylmethane and aniline resins, condensates of aliphatic amines and aliphatic dicarboxylic acids, dicyandiamide and its derivatives, various imidazoles and imidazoline compounds, adipic acid, sebacic acid, phthalic acid, maleic acid, Condensates of aldehydes with polycarboxylic acids such as merit acid, benzophenone dicarboxylic acid, benzophenone tetracarboxylic acid, pyromellitic acid or their anhydrides, dihydrazides such as adipic acid and phthalic acid, phenol, cresol, xylenol, bisphenol A, etc. And novolaks, carboxylic acid amides, methylolated melamines, block isocyanurates and the like. Among these, an acid anhydride-based curing agent is preferable because it improves the curing characteristics of the obtained powder coating material.

  The ratio of the curing agent to the epoxy resin can be adjusted depending on the type of the epoxy resin and the curing agent used. Preferably, generally, the curing agent is used in the range of 0.6 to 1.2 equivalents relative to the epoxy resin. In the above range, good curing characteristics can be obtained. If necessary, curing accelerators such as tertiary amines, imidazoles, and organophosphorus compounds may be used for these curing agents. Among them, the use of organophosphorus compounds further enhances flame retardancy. desirable.

  The total amount of the epoxy resin and the curing agent is preferably 10 to 80% by mass and more preferably 25 to 60% by mass with respect to the total mass of the epoxy resin powder coating material. Thereby, the applicability | paintability of a powder coating material can be made favorable. If the blending amount is less than the above lower limit value, the smoothness of the coating film may be lowered. is there.

  Examples of the filler used in the present invention include calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide, crystal or fused silica, surface-treated silica, talc, kaolin, clay, mica, dolomite, wort Examples include lastonite, glass fiber, glass beads, zircon, titanium compounds, and molybdenum compounds. These may be used alone or in combination. Among these, fused silica is preferable.

  The blending amount of the filler is preferably 50% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 70% by mass or less, with respect to the total mass of the epoxy resin powder coating material. Thereby, the applicability | paintability of a powder coating material can be made favorable. If the blending amount is less than the above lower limit, there may be a problem in appearance such as sagging or toggling during firing, and the mechanical strength of the coating film may not be sufficient. On the other hand, when the amount is larger than the upper limit, the smoothness of the coating film may be lowered.

  Further, the particle size of the filler is not particularly limited, but usually an average particle size of 5 to 30 μm is preferably used. Thereby, favorable fluidity | liquidity is provided to a powder coating material, coating property improves more, and also it can be made optimal about the mechanical strength of a coating film.

  A metal salt compound is used as the laser color former used in the present invention. Examples of the metal salt compound include nickel compounds such as nickel lactate, nickel hypophosphite and nickel formate; copper compounds such as copper carbonate and copper oxalate; zirconium compounds such as zirconium silicate; lead compounds and the like. These can be used alone or in combination. Among these, it is preferable to use a metal salt compound other than the lead compound, and it is more preferable to use a copper compound or a zirconium compound. Thereby, sufficient coloring property can be imparted with a relatively small amount of addition, and the environmental load can be reduced.

  The blending amount of the laser color former is preferably 0.5 to 20% by mass and more preferably 0.5 to 10% by mass with respect to the total mass of the powder coating material. If the blending amount is less than the lower limit, color developability may not be sufficient, while if it exceeds the upper limit, moisture resistance may be significantly reduced.

  The phosphate ester flame retardant used in the present invention preferably has a high phosphorus content and is solid at room temperature in order to impart sufficient flame retardancy, such as triphenyl phosphate or aromatic condensed phosphate ester. Etc.

  The phosphoric ester-based flame retardant is preferably blended so that the content of the phosphorus component is 1 to 3% by mass with respect to the mass of the epoxy resin used, and 2 to 2.5% by mass. It is more preferable to mix. If the phosphorus content is below the lower limit, sufficient flame retardancy may not be obtained, and even if the upper limit is exceeded, further improvement in the effect of imparting flame retardancy may not be observed. Moreover, mechanical strength, such as heat cycle resistance of the obtained powder coating material, can be improved by mix | blending a phosphate ester type flame retardant so that it may become a phosphorus component in the said range.

The flame-retardant epoxy resin powder coating material of the present invention containing the above components has a thermal expansion coefficient of 10 × 10 ⁻⁵ / ° C. or less, which is Tg or more. The flame-retardant epoxy resin powder coating of the present invention has a thermal expansion coefficient of 10 × 10 ⁻⁵ / ° C. or less, which is improved in mechanical strength such as heat cycle resistance. The reason for this is not necessarily clear, but it is considered that the difference in the coefficient of thermal expansion from the electronic component is reduced.
The lower limit of Tg or more heat expansion coefficient of the flame retardant epoxy resin powder coating of the present invention is not specifically limited, usually at 8.5 × 10 -5 ^/ ℃ or more, preferably 5 × 10 ^{- 5} / ° C or higher.
Here, the thermal expansion coefficient equal to or higher than Tg is a value measured by a thermomechanical analysis (TMA) method in accordance with JIS C 2161, and represents an average value of thermal expansion coefficients in a region equal to or higher than Tg and equal to or lower than 160 ° C. .

  In the epoxy resin powder coating of the present invention, the above Tg is preferably 100 ° C. or lower, more preferably 95 ° C. or lower. When Tg is not more than the above upper limit, the stress relaxation ability of the epoxy resin powder coating is improved, and as a result, the heat cycle resistance of the epoxy resin powder coating can be improved. The lower limit value of Tg of the epoxy resin powder coating of the present invention is not particularly limited, but is usually 60 ° C. or higher.

In addition, the epoxy resin powder paint of the present invention preferably has a flexural modulus measured in accordance with JIS K 6911 of 1.0 × 10 ⁴ MPa or more. When the flexural modulus is equal to or higher than the lower limit, mechanical strength such as heat cycle resistance is further improved. In addition, although the upper limit of the bending elastic modulus of the epoxy resin powder coating of the present invention is not particularly limited, it is usually 1.3 × 10 ⁴ MPa or less.

  In addition to the components described above, the powder coating material of the present invention may contain additives such as pigments, leveling agents, coupling agents, and antifoaming agents as necessary. In order to enhance the flame retardancy, a resin having a cyanurate ring skeleton such as a silicone resin or a melamine resin, or a non-halogen flame retardant aid such as zinc borate or expandable graphite may be used.

  The flame-retardant epoxy resin powder coating of the present invention can be obtained by appropriately selecting each component described above and appropriately adjusting the blending amount of each component.

  In the present invention, the method for producing the powder coating material is not particularly limited, and a general method can be used. As an example, the raw material components blended in a predetermined composition ratio are sufficiently uniformly mixed with a mixer, then melt mixed with an extruder or a twin-screw kneader, and then pulverized and classified to an appropriate particle size with a pulverizer. be able to.

  Although the epoxy resin powder coating material of this invention is not specifically limited, For example, it can be used conveniently for the exterior coating film of electrical / electronic components, such as a ceramic capacitor.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.

The raw material components in the compounding amounts (parts by mass) shown in Table 1 were mixed by a mixer, melted and kneaded, and then pulverized by a pulverizer to obtain an epoxy resin powder coating having an average particle size of 40 to 60 μm. The obtained powder coating was evaluated for the following items. The results are shown in the table below.
1. Epoxy resin / bisphenol A type epoxy resin: manufactured by Mitsubishi Chemical Corporation, “Epicoat 1003” (epoxy equivalent 720)
Brominated epoxy resin: manufactured by Nippon Steel Chemical Co., Ltd. “Epototo YDB-400” (epoxy equivalent 400)
2. Curing agent BTDA: benzophenone tetracarboxylic acid anhydride TMA: trimellitic anhydride 3. Curing accelerator, TPP: Triphenylphosphine Filler / Fused Silica: manufactured by Tatsumori Co., Ltd. “RD-8” (average particle size 15 μm)
5. Pigment / White pigment (titanium oxide): “TTO-55” manufactured by Ishihara Sangyo Co., Ltd.
・ Blue pigment (cyanine blue): manufactured by Sumitomo Chemical Co., Ltd. ・ "Cyanine blue GH"
6). Additives / Silane coupling agents: GE Toshiba Silicone "A-187"
• Leveling agent: Surface • Specialties • Modaflow powder Flame retardant, phosphate ester: Daihachi Chemical Co., Ltd. “PX-200” (phosphorus content 8.9% by mass)
-Antimony trioxide 8. 8. Laser color former, nickel hypophosphite, copper compound, zirconium compound Ion scavengers and hydrotalcites: “DHT-4A” manufactured by Kyowa Chemical Industry Co., Ltd.

(Test method)
1. Gelation time: Measured with a hot plate at 165 ° C. according to JIS C 2161.
2. Flame retardancy test: The thickness of the test plate was 0.8 mm, and the measurement was performed according to the UL94 method.
3. Glass transition temperature (Tg): Measured by the TMA method according to JIS C 2161.
4). Thermal expansion coefficient (Tg or less, / ° C.): Measured by the TMA method in accordance with JIS C 2161, and the average value of thermal expansion coefficients in the region of 30 ° C. or more and Tg or less was calculated.
5. Thermal expansion coefficient (Tg or more, / ° C.): Measured by the TMA method in accordance with JIS C 2161, and the average value of thermal expansion coefficients in the region of Tg or more and 160 ° C. or less was calculated.
6). Bending strength (MPa): Measured by bending strength according to JIS K 6911.
7). Heat cycle resistance (−40 ° C./30 minutes to 125 ° C./30 minutes): The presence or absence of cracks was confirmed using powder-coated electronic parts having a film thickness of 0.75 mm or more.
8). Heat cycle resistance (−40 ° C./30 minutes to 85 ° C./30 minutes): Using electronic parts powder-coated with a film thickness of 0.75 mm or more, the presence or absence of cracks was confirmed.
9. Flexural modulus (MPa): The flexural modulus was measured according to JIS K 6911.

In all of the epoxy resin powder coatings of Examples, the thermal expansion coefficient of Tg or more was 10 × 10 ⁻⁵ / ° C. or less. Such an epoxy resin powder coating has a heat cycle resistance of 2500 or more in a heat cycle test of −40 ° C./30 minutes to 125 ° C./30 minutes, and −40 ° C./30 minutes to 85 ° C./30 minutes. In the heat cycle test, a heat cycle resistance of 1500 or more, a bending strength of 110 MPa or more, and a flexural modulus of 1.0 × 10 ⁴ MPa or more were provided.
On the other hand, the powder coating of the comparative example containing a brominated epoxy resin has a heat cycle resistance of 500 or less in a heat cycle test of −40 ° C./30 minutes to 125 ° C./30 minutes, and −40 ° C./30 minutes. In the heat cycle test at 85 ° C./30 minutes, the heat cycle resistance was 500 or less. Moreover, the powder coating material of the comparative example had a bending strength of less than 110 MPa and a bending elasticity of less than 1.0 × 10 ⁴ MPa.

Claims (8)

An epoxy resin powder coating containing an epoxy resin, a curing agent, a filler, a laser color former, and a phosphate ester flame retardant,
A flame-retardant epoxy resin powder coating material, wherein the epoxy resin powder coating material has a coefficient of thermal expansion equal to or higher than a glass transition temperature of 10 × 10 ⁻⁵ / ° C.   The flame retardant epoxy resin powder coating material according to claim 1, wherein the filler is 50% by mass or more based on the mass of the epoxy resin powder coating material.   The flame retardant epoxy resin powder coating according to claim 1, wherein the laser color former contains a copper compound or a zirconium compound.   The flame retardant epoxy resin powder coating material according to claim 1, wherein the filler is fused silica.   The flame retardant epoxy resin powder coating according to claim 1, wherein the curing agent contains an acid anhydride. The flame-retardant epoxy resin powder coating material according to claim 1, wherein the epoxy resin powder coating material has a flexural modulus of 1.0 × 10 ⁴ MPa or more.   The flame-retardant epoxy resin powder coating material according to claim 1, wherein the epoxy resin powder coating material has a glass transition temperature of 100 ° C. or lower.   The flame retardant epoxy resin powder coating according to claim 1, wherein the epoxy resin powder coating is used for an exterior coating film of an electric / electronic component.