Electrical insulation resin composition

Abstract

Provided is an electrical insulation resin composition capable of achieving both flame retardancy and tracking resistance. The electrical insulation resin composition according to an embodiment comprises a polyalkylene terephthalate and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol. The amount of the condensate with respect to 100 parts by mass of polyalkylene terephthalate is 9-19 parts by mass.

Description

Electrical insulating resin composition

[0001] The present invention relates to an electrical insulating resin composition.

[0002] Polyalkylene terephthalates, such as polybutylene terephthalate and polyethylene terephthalate, are widely used in fields such as electrical and electronic components due to their excellent physical properties, moldability, and mechanical characteristics. Because polyalkylene terephthalates themselves have poor flame retardancy, flame retardants are added to them in applications where flame retardancy is required. While various compounds have been used as flame retardants, the use of polymeric flame retardants has become increasingly desirable in recent years due to environmental and other considerations.

[0003] For example, Patent Document 1 discloses a flame-retardant resin composition in which a thermoplastic polyester resin such as polybutylene terephthalate is blended with a halogen-containing polyhydroxypolyether resin as a flame retardant obtained by reacting a tetrabromobisphenol A-epichlorohydrin epoxy resin with tetrabromobisphenol A, and antimony trioxide as a flame retardant aid.

[0004] Special Publication No. 8-26228 Publication No. 60-4236

[0005] As described above, flame retardancy can be imparted to polyalkylene terephthalate by adding a flame retardant, but the addition of a flame retardant causes a problem of a decrease in electrical insulation, particularly tracking resistance. Here, tracking resistance refers to resistance to tracking. Tracking refers to the formation of conductive paths (tracks) on the surface of an insulator, which can lead to short circuits (dielectric breakdown) between wirings.

[0006] An object of an embodiment of the present invention is to provide an electrical insulating resin composition that can achieve both flame retardancy and tracking resistance.

[0007] The present invention includes the following embodiments: [1] An electrically insulating resin composition comprising a polyalkylene terephthalate and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol, wherein the amount of the condensate is 9 to 19 parts by mass per 100 parts by mass of the polyalkylene terephthalate. [2] The condensate comprises a compound represented by the following general formula (1): R in formula (1) １ is -C(CH ３ ) ２ -or-SO ２ -, and n is a number of 1 or more. [3] The electrically insulating resin composition according to [1] or [2], further comprising one or more flame retardant aids selected from the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, potassium antimonate, zinc stannate, and zinc borate. [4] The electrically insulating resin composition according to [3], wherein the amount of the flame retardant aid is 1 to 100 parts by mass per 100 parts by mass of the condensate. [5] The electrically insulating resin composition according to any one of [1] to [4], wherein the polyalkylene terephthalate comprises polybutylene terephthalate. [6] Use of a resin composition for electrical insulation, comprising polyalkylene terephthalate and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol, wherein the amount of the condensate is 9 to 19 parts by mass per 100 parts by mass of the polyalkylene terephthalate.

[0008] The electrical insulating resin composition according to the embodiment of the present invention can achieve both flame retardancy and tracking resistance.

[0009] The electrical insulating resin composition according to the present embodiment contains a polyalkylene terephthalate and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol, with the amount of the condensate being 9 to 19 parts by mass per 100 parts by mass of the polyalkylene terephthalate. According to this embodiment, high flame retardancy can be achieved and high tracking resistance can be obtained simply by adding a small amount of the condensate, which serves as a flame retardant. Therefore, both flame retardancy and tracking resistance can be achieved. Furthermore, while it is generally difficult to achieve a V-0 rating in a thin molded article in the UL-94 test, this embodiment makes it possible to achieve a V-0 rating even in a thin molded article. Furthermore, because only a small amount of the condensate, which serves as a flame retardant, is added, it is easy to maintain the inherent resin properties of the polyalkylene terephthalate at a high level.

[0010] Polyalkylene terephthalate is a polyester resin obtained by polycondensation reaction of terephthalic acid and an aliphatic diol, such as ethylene glycol, propylene glycol, or butylene glycol.

[0011] Specific examples of polyalkylene terephthalate include polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. Among these, polybutylene terephthalate (PBT) is preferred. That is, in one embodiment, the polyalkylene terephthalate preferably contains polybutylene terephthalate. In this case, the amount of polybutylene terephthalate is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the polyalkylene terephthalate, and may be 100% by mass.

[0012] In this embodiment, a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol is used as the flame retardant. The condensate is formed by dehydrochlorination condensation between cyanuric chloride and tetrabromobisphenol and between cyanuric chloride and tribromophenol.

[0013] Examples of tetrabromobisphenol include tetrabromobisphenol A and tetrabromobisphenol S.

[0014] In one embodiment, the condensate is a condensate of tetrabromobisphenol A and / or tetrabromobisphenol S, cyanuric chloride, and tribromophenol, and preferably contains a compound (1) represented by the following general formula (1):

[0015] R in formula (1) １ is -C(CH ３ ) ２ -or-SO ２ -, preferably -C(CH ３ ) ２ In formula (1), n ​​represents the average number of repeating units and is a number of 1 or more. n is preferably 1 to 5, more preferably 1.8 to 4, and even more preferably 2 or more and less than 3. Here, n is calculated from the weight average molecular weight of compound (1).

[0016] When the condensate contains compound (1), it is preferable that the compound (1) is the main component, and the amount of compound (1) in 100% by mass of the condensate is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

[0017] The condensate can be obtained, for example, by treating tetrabromobisphenol A and / or tetrabromobisphenol S, cyanuric chloride, and tribromophenol with an alkali. In one embodiment, the condensate can be produced by the method described in Japanese Patent Publication No. 60-4236, and can be obtained by treating a moles of tetrabromobisphenol A and / or tetrabromobisphenol S and (3-2a) moles of tribromophenol, relative to 1 mole of cyanuric chloride, with 3 equivalents or more of alkali in a solvent. Here, a is greater than 0 and less than 1.5, and preferably 0.5 or greater and less than 1.

[0018] The weight average molecular weight (Mw) of the condensate is preferably 2000 to 6000, more preferably 2000 to 5000, more preferably 2200 to 4000, and even more preferably 2500 to 3500. By using a condensate having a relatively small molecular weight in this way, the fluidity of the resin composition is increased, making it easier to thin the wall of a molded article.

[0019] In this specification, the weight-average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated using a calibration curve based on standard polystyrene. Specifically, a tetrahydrofuran (THF) solution with a sample concentration of 0.2% by mass is prepared and filtered through a membrane filter (0.45 μm) to obtain a measurement solution. Using the following measurement device and column, molecular weight measurements are performed using THF as the eluent, a column temperature of 40°C, a sample injection volume of 20 μL, and a flow rate of 1.0 mL / min, and the weight-average molecular weight can be calculated using a calibration curve based on standard polystyrene. Measurement device: Prominance-I (Shimadzu Corporation); Column: TSKgel G2000Hxl, TSKgel G3000Hxl, and TSKgel G4000Hxl (Shimadzu Corporation) connected in series.

[0020] The amount of the condensate in the electrical insulating resin composition is 9 to 19 parts by mass, preferably 12 to 19 parts by mass, more preferably 15 to 19 parts by mass, and even more preferably 17 to 18 parts by mass, relative to 100 parts by mass of polyalkylene terephthalate.

[0021] The electrical insulating resin composition may further contain a flame retardant aid. The flame retardant aid is preferably one or more selected from the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, potassium antimonate, zinc stannate, and zinc borate. The inclusion of such a flame retardant aid can further improve flame retardancy. The flame retardant aid is more preferably one or more selected from the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, and potassium antimonate, and even more preferably antimony trioxide and / or antimony pentoxide.

[0022] The amount of the flame retardant aid is preferably 1 to 100 parts by mass, more preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass, and even more preferably 20 to 50 parts by mass, relative to 100 parts by mass of the condensate.

[0023] The insulating resin composition may further contain a fibrous reinforcing material. By containing the fibrous reinforcing material, the strength of the molded article can be improved. Examples of the fibrous reinforcing material include glass fiber and carbon fiber.

[0024] When a fibrous reinforcing material is blended, the amount is not particularly limited, but may be, for example, 1 to 100 parts by mass, 5 to 80 parts by mass, or 10 to 60 parts by mass relative to 100 parts by mass of polyalkylene terephthalate.

[0025] The electrical insulating resin composition may further contain an inorganic filler. Examples of inorganic fillers include metal silicates and titanium oxide. Examples of metal silicates include magnesium silicate-based fillers such as talc, aluminum silicate-based fillers such as kaolin, aluminum-potassium silicate-based fillers such as mica, and calcium silicate-based fillers such as wollastonite. Among these, adding a metal silicate can enhance the effect of improving tracking resistance.

[0026] When an inorganic filler (more preferably a metal silicate) is blended, the amount thereof is not particularly limited, but may be, for example, 1 to 100 parts by mass, 5 to 80 parts by mass, or 10 to 60 parts by mass relative to 100 parts by mass of polyalkylene terephthalate.

[0027] The electrical insulating resin composition may further contain various additives such as an antioxidant, an anti-dripping agent, an ultraviolet absorber, a crystal nucleating agent, a crystallization accelerator, and a colorant (for example, a pigment).

[0028] Examples of the antioxidant include phenol-based antioxidants, phosphite-based antioxidants, thioether-based antioxidants, etc. When an antioxidant is contained, the amount thereof is not particularly limited, and may be, for example, 0.05 to 5 parts by mass or 0.1 to 3 parts by mass relative to 100 parts by mass of the polyalkylene terephthalate.

[0029] Examples of the anti-dripping agent include polytetrafluoroethylene (PTFE). When an anti-dripping agent is contained, the amount thereof is not particularly limited, and may be, for example, 0.05 to 5 parts by mass or 0.1 to 3 parts by mass per 100 parts by mass of polyalkylene terephthalate.

[0030] The method for preparing the resin composition for electrical insulation is not particularly limited, and examples thereof include a method in which a polyalkylene terephthalate and the condensate, and further optional components such as a flame retardant aid, a fibrous reinforcing material, an inorganic filler, and other additives are blended and melt-mixed using a mixer such as an extruder.

[0031] The obtained electrical insulating resin composition can be molded as desired by any molding method such as injection molding, extrusion molding, vacuum molding, etc., to obtain a molded product.

[0032] The resin composition according to this embodiment can be used for various electrical insulation applications. That is, a molded article produced from the resin composition according to this embodiment has excellent flame retardancy and tracking resistance, and therefore can be preferably used for, for example, voltage-resistant parts used as electrical and electronic parts and automotive parts, such as sockets, coils, terminal blocks, plugs, switches, relay parts, and breaker parts. Therefore, the resin composition according to this embodiment is also referred to as a resin composition for voltage-resistant parts.

[0033] As described above, the electrical insulating resin composition according to this embodiment can exhibit flame retardancy even when molded into a thin shape. Therefore, it is suitable for use in producing a thin molded article having a thickness of, for example, 0.4 to 1.6 mm, more preferably 0.5 to 1.0 mm, and even more preferably less than 1.0 mm. Even in such a thin molded article, both flame retardancy and tracking resistance can be achieved.

[0034] Examples will be described in detail below along with comparative examples, but the present invention is not limited to these examples.

[0035] Details of the raw materials used in the examples and comparative examples are as follows: [Flame retardant] Flame retardant 1: a compound represented by the above formula (1) (where R１ is -C(CH ３ ) ２ Condensation product of tetrabromobisphenol A, cyanuric chloride and tribromophenol (TBBA / CC / TBP) containing tetrabromobisphenol A, cyanuric chloride and tribromophenol. The synthesis method is as follows.

[0036] A 5L glass four-neck flask equipped with a reflux condenser, thermometer, dropping funnel, and stirrer was charged with 543.9g (1.0mol) of tetrabromobisphenol A (TBBA), 661.6g (2.0mol) of tribromophenol (TBP), 245.3g (1.33mol) of cyanuric chloride (CC), and 2L of methylene chloride. The mixture was cooled to 5°C with stirring, and 352.0g of a 50% by mass aqueous NaOH solution was slowly added dropwise from the dropping funnel while maintaining the temperature of the reaction solution below 10°C. After completion of the dropwise addition, the mixture was maintained below 10°C for 30 minutes, and then heated at a rate of 10°C / h until the solution reached reflux. After maintaining the reflux temperature for 3 hours, the reaction solution was washed with water and reprecipitated in 2L of methanol. The resulting precipitate was then washed sequentially with 1N hydrochloric acid, 1L of water, and 2L of methanol. After drying at 80°C for 12 hours, a white powder was obtained in a yield of 98% by mass, and the bromine content of the powder was 60.0% by mass. The weight average molecular weight (Mw) of the powder measured by GPC in a THF solution was 3,000. The chemical reaction formula is as follows:

[0037]

[0038] Flame retardant 2: Comparative example, "SR-T20000" manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., brominated bisphenol A epoxy resin, bromine content 52% by mass

[0039] Flame retardant 3: Comparative example, "SAYTEX HP-7010" manufactured by Albemarle, brominated polystyrene, bromine content 68% by mass

[0040] Flame retardant 4: Comparative example, "Pyroguard (registered trademark) SR-460B" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., tribromophenol polycondensate, bromine content 62% by mass

[0041] [Polyalkylene terephthalate] PBT (GF 30%): "Toraycon 1101G-30" manufactured by Toray Industries, Inc., a glass fiber reinforced polybutylene terephthalate containing 30% by mass of glass fiber. The figures in parentheses in the table indicate the amount of glass fiber blended, and the remainder indicates the amount of PBT blended.

[0042] [Flame retardant synergists] Flame retardant synergist 1: antimony trioxide, "Pyroguard (registered trademark) AN-800T" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. Flame retardant synergist 2: antimony pentoxide, "NA-1030" manufactured by Nissan Chemical Industries, Ltd.

[0043] [Metal silicate] Metal silicate: talc, "Micron White #5000S" manufactured by Hayashi Kasei Co., Ltd.

[0044] [Additives] Stabilizer 1: hindered phenol-based antioxidant, "Irganox 1010" manufactured by BASF Japan Ltd. Stabilizer 2: phosphite-based antioxidant, "Irgafos 168" manufactured by BASF Japan Ltd. Anti-drip agent: "FluonPTFE CD145E (PTFE)" manufactured by AGC Corporation

[0045] [Evaluation Method] Flame retardancy: Measured in accordance with UL-94 using a strip-shaped test specimen (length 127 mm x width 12.7 mm x thickness 0.8 mm). Flame retardancy was evaluated according to the UL-94 criteria using a four-level rating system: V-0 (excellent), V-1 (good), V-2 (fair), and N.R. (fail). V-2 or higher is acceptable, and N.R. is outside the UL-94 criteria and indicates poor flame retardancy.

[0046] Tracking resistance: Comparative tracking index (CTI) was measured using a square plate test piece (50 mm x 50 mm x 3.2 mm thick) in accordance with IEC 60112 of the International Electrotechnical Commission. Using Solution A, electrolyte was dropped between the electrodes on the surface of the square plate test piece, and the voltage that could withstand 50 drops without tracking was defined as the CTI. CTI of 600 V or more was rated as "A" (very good tracking resistance), CTI of less than 600 V and 250 V or more was rated as "B" (good tracking resistance), and CTI of less than 250 V was rated as "C" (poor tracking resistance).

[0047] [First Experimental Example] Pellets were produced by extruding the composition (parts by mass) shown in Table 1 below using a twin-screw extruder at 260°C and a screw rotation speed of 200 rpm. These pellets were injection molded under conditions of a cylinder temperature of 260°C and a mold temperature of 80°C to produce test specimens. Flame retardancy and tracking resistance were evaluated using the obtained test specimens.

[0048]

[0049] The results are shown in Table 1. In the first experimental example, for each of flame retardants 1 to 4, the minimum amount of flame retardant required to achieve a flame retardancy rating of V-0 was determined in a preliminary test, and in each example and comparative example, the amount of flame retardant was set to that minimum amount, and whether or not a difference in tracking resistance would occur in that case was evaluated. As a result, Examples 1 to 3, which used flame retardant 1 (TBBA / CC / TBP) according to this embodiment, exhibited excellent tracking resistance. In contrast, Comparative Examples 1 to 3, which used polymeric flame retardants 2 to 4, which are different from the flame retardant according to this embodiment, exhibited poor tracking resistance.

[0050] [Second Experimental Example] Test specimens were prepared in the same manner as in Experimental Example 1, except for the formulation (parts by mass) shown in Table 2 below, and the flame retardancy and tracking resistance were evaluated using the obtained test specimens. Note that Example 1 in Table 2 corresponds to Example 1 of the first experimental example.

[0051]

[0052] The results are shown in Table 2. In the second experimental example, in Comparative Examples 4 to 6, the blending amount of the flame retardant was the same as in Example 1, and it was confirmed whether the effect of achieving both flame retardancy and tracking resistance could be achieved. In Comparative Examples 4 and 5, the amount of flame retardant was reduced compared to Comparative Examples 1 and 2, but the tracking resistance was still poor and the flame retardancy was also reduced compared to Example 1. In Comparative Example 6, like Comparative Example 3, the flame retardancy was excellent but the tracking resistance was poor. Thus, when flame retardants 2 to 4, which are different from the flame retardant according to this embodiment, were used, it was not possible to achieve both flame retardancy and tracking resistance.

[0053] In the second experimental example, evaluations were also conducted for Examples 4 to 7 and Comparative Example 7, in which the blending amount of the flame retardant according to the present embodiment was varied. As a result, in Example 4, in which the amount of flame retardant 1 was increased relative to Example 1, to 19 parts by mass relative to 100 parts by mass of PBT, the flame retardancy and tracking resistance were excellent, similar to Example 1. In Examples 5 to 7, in which the amount of flame retardant 1 was reduced relative to Example 1, to 9 to 14.3 parts by mass relative to 100 parts by mass of PBT, the flame retardancy was lower than in Example 1, but was still at the pass level of V-2 and the tracking resistance was also good. In contrast, in Comparative Example 7, in which the blending amount of flame retardant 1 was 21 parts by mass relative to 100 parts by mass of PBT, the flame retardancy was excellent but the tracking resistance was poor, and it was not possible to achieve both flame retardancy and tracking resistance at the same time.

[0054] [Experimental Example 3] Test specimens were prepared in the same manner as in Experimental Example 1, except for the formulation (parts by mass) shown in Table 3 below, and the flame retardancy and tracking resistance were evaluated using the obtained test specimens. Note that Example 1 in Table 3 corresponds to Example 1 of Experimental Example 1.

[0055]

[0056] The results are shown in Table 3. In Example 8, by blending a metal silicate, it was possible to improve the tracking resistance compared to Example 1 while maintaining excellent flame retardancy.

[0057] The various numerical ranges described in this specification can be arbitrarily combined with their respective upper and lower limit values, and all such combinations are considered to be preferred numerical ranges described in this specification. Furthermore, the description of a numerical range as "X to Y" means from X to Y.

[0058] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their omissions, substitutions, modifications, etc. are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents.

Claims

1. An electrical insulating resin composition comprising a polyalkylene terephthalate and a condensate of tetrabromobisphenol, cyanuric chloride and tribromophenol, wherein the amount of the condensate per 100 parts by mass of the polyalkylene terephthalate is 9 to 19 parts by mass.

2. The condensate contains a compound represented by the following general formula (1): R in formula (1) １ is -C(CH ３ ) ２ -or-SO ２ 2. The electrically insulating resin composition according to claim 1, wherein n represents - and n represents a number of 1 or more.

3. The electrically insulating resin composition according to claim 1 or 2, further comprising one or more flame retardant aids selected from the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, potassium antimonate, zinc stannate, and zinc borate.

4. The electrically insulating resin composition according to claim 3, wherein the amount of said flame retardant aid is 1 to 100 parts by mass per 100 parts by mass of said condensate.

5. The electrically insulating resin composition according to claim 1 or 2, wherein the polyalkylene terephthalate comprises polybutylene terephthalate.

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