Resin composition for electrical insulation

Abstract

The present invention provides a resin composition for electrical insulation that can balance flame retardancy and tracking resistance. The resin composition for electrical insulation according to the present invention contains: a polyalkylene terephthalate; and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol. The amount of the condensate is 9 to 19 parts by mass relative to 100 parts by mass of the polyalkylene terephthalate.

Description

Technical Field

[0001] This invention relates to resin compositions for electrical insulation. Background Technology

[0002] Polyalkylene terephthalates (PET), such as polybutylene terephthalate (PET) and polyethylene terephthalate (PET), exhibit excellent physical properties, processability, and mechanical properties, and are therefore widely used in electrical / electronic components and other fields. PET itself lacks flame retardancy; therefore, flame retardants are added for applications requiring flame retardancy. Various compounds have been used as flame retardants, but in recent years, from environmental and other perspectives, there is a growing demand for polymeric flame retardants.

[0003] For example, Patent Document 1 discloses a flame-retardant resin composition in which a halogen-containing polyhydroxy polyether resin obtained by reacting tetrabromobisphenol A-epiochlorohydrin type epoxy resin, which is used as a flame retardant, with tetrabromobisphenol A is added to a thermoplastic polyester resin such as polybutylene terephthalate, and antimony trioxide is added as a flame-retardant additive.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 8-26228

[0007] Patent Document 2: Japanese Patent Publication No. 60-4236 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] As mentioned above, flame retardancy can be imparted by adding flame retardants to polyethylene terephthalate (PET). However, the addition of flame retardants results in a decrease in electrical insulation properties, particularly resistance to tracking. Here, resistance to tracking refers to the resistance to inducing tracking. Tracking refers to the short circuit (insulation breakdown) that occurs between wirings by forming a conductive path (trace) on the surface of the insulator.

[0010] The purpose of this invention is to provide an electrical insulating resin composition that can combine flame retardancy and resistance to tracking.

[0011] Technical means for solving problems

[0012] The present invention includes the embodiments shown below.

[0013] [1] An electrical insulating resin composition comprising:

[0014] Polyalkylene terephthalate; and

[0015] A condensation of tetrabromobisphenol, cyanuric chloride, and tribromophenol

[0016] The amount of the condensate is 9 to 19 parts by mass relative to 100 parts by mass of the above-mentioned polyalkylene terephthalate.

[0017] [2] According to the electrical insulating resin composition described in [1], wherein,

[0018] The above condensate comprises compounds represented by the following general formula (1),

[0019] [Chemistry 1]

[0020]

[0021] R in equation (1) 1 It represents -C(CH3)2- or -SO2-, and n represents a number greater than 1.

[0022] [3] The electrical insulating resin composition according to [1] or [2], wherein,

[0023] It also includes one or more flame retardant additives selected from the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, potassium antimonate, zinc stannate, and zinc borate.

[0024] [4] The electrical insulating resin composition according to [3], wherein,

[0025] The amount of the flame retardant additive is 1 to 100 parts by mass relative to 100 parts by mass of the above condensate.

[0026] [5] The electrical insulating resin composition according to any one of [1] to [4], wherein,

[0027] The aforementioned polyalkylene terephthalate includes polybutylene terephthalate.

[0028] [6] Use of a resin composition for electrical insulation purposes, wherein,

[0029] The resin composition contains: polyalkylene terephthalate; and a condensate of tetrabromobisphenol, cyanuric chloride and tribromophenol, wherein the amount of the condensate is 9 to 19 parts by mass relative to 100 parts by mass of the above-mentioned polyalkylene terephthalate.

[0030] Invention Effects

[0031] If it is the electrical insulating resin composition involved in the embodiments of the present invention, it can take into account both flame retardancy and resistance to tracking. Detailed Implementation

[0032] The electrical insulating resin composition of this embodiment contains: polyalkylene terephthalate, and a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol, wherein the amount of the condensate is 9 to 19 parts by mass relative to 100 parts by mass of polyalkylene terephthalate. According to this embodiment, only a small amount of the condensate as a flame retardant is added to exhibit high flame retardancy and high resistance to tracking. Therefore, both flame retardancy and tracking resistance can be achieved. Furthermore, generally, thin molded articles are difficult to achieve a V-0 rating in the UL-94 flammability test, but according to this embodiment, even thin molded articles can achieve V-0. In addition, because of the small amount of the condensate as a flame retardant added, the original resin properties of polyalkylene terephthalate are easily maintained to a higher degree.

[0033] Polyalkylene terephthalate (PET) is a polyester resin obtained through a polycondensation reaction of terephthalic acid and aliphatic diols as the main components. Examples of aliphatic diols include ethylene glycol, propylene glycol, and butanediol.

[0034] Specific examples of polyalkylene terephthalate include polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. Polybutylene terephthalate (PBT) is preferred. That is, in one embodiment, the polyalkylene terephthalate preferably comprises polybutylene terephthalate. In this case, the amount of polybutylene terephthalate in 100% by mass of the polyalkylene terephthalate is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and can be 100% by mass.

[0035] In this embodiment, a condensate of tetrabromobisphenol, cyanuric chloride, and tribromophenol can be used as a flame retardant. This condensate is formed by dehydrochlorination condensation between cyanuric chloride and tetrabromobisphenol, and between cyanuric chloride and tribromophenol.

[0036] Examples of tetrabromobisphenols include tetrabromobisphenol A and tetrabromobisphenol S.

[0037] In one embodiment, the condensate is a condensate of tetrabromobisphenol A and / or tetrabromobisphenol S, cyanuric chloride and tribromophenol, preferably comprising compound (1) represented by the following general formula (1).

[0038] [Chemistry 2]

[0039]

[0040] R in equation (1) 1The value is -C(CH3)2- or -SO2-, preferably -C(CH3)2-. In formula (1), n ​​is the average number of repeating units, representing a number greater than or equal to 1. n is preferably 1 to 5, more preferably 1.8 to 4, and even more preferably 2 or more but less than 3. Here, n can be calculated based on the weight-average molecular weight of compound (1).

[0041] When the above condensate contains compound (1), it is preferable that 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, and even more preferably 95% by mass or more, and can be 100% by mass.

[0042] The aforementioned condensate is 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 manufactured by the method described in Japanese Patent Publication No. 60-4236, wherein a moles of tetrabromobisphenol A and / or tetrabromobisphenol S and (3-2a) moles of tribromophenol are treated in a solvent with 3 or more equivalents of alkali relative to 1 mole of cyanuric chloride. Here, a is greater than 0 and less than 1.5, preferably 0.5 or more and less than 1.

[0043] The weight-average molecular weight (Mw) of the above-mentioned condensate is preferably 2000-6000, more preferably 2000-5000, even more preferably 2200-4000, and even more preferably 2500-3500. By using a smaller molecular weight as the condensate in this way, the flowability of the resin composition is improved, and the thinning of the molded article becomes easier.

[0044] In this specification, the weight-average molecular weight is determined by GPC (gel permeation chromatography) using a calibration curve based on standard polystyrene. Specifically, a 0.2% by mass tetrahydrofuran (THF) solution is prepared and filtered through a 0.45 μm membrane filter to obtain the assay solution. Using the apparatus and column described below, with THF as the eluent, the molecular weight is determined at a column temperature of 40°C, a sample injection volume of 20 μL, and a flow rate of 1.0 mL / min. The weight-average molecular weight is calculated using a calibration curve based on standard polystyrene.

[0045] Measurement device: Prominance-I (manufactured by Shimadzu Corporation)

[0046] Column: Connect TSKgelG2000Hxl, TSKgelG3000Hxl, and TSKgelG4000Hxl (manufactured by Shimadzu Corporation) in series.

[0047] In the resin composition for electrical insulation, the amount of the condensate relative to 100 parts by weight of polyalkylene terephthalate is 9 to 19 parts by weight, preferably 12 to 19 parts by weight, more preferably 15 to 19 parts by weight, and even more preferably 17 to 18 parts by weight.

[0048] The resin composition for electrical insulation may further contain flame-retardant additives. Preferably, the flame-retardant additive is selected from one or more of the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, potassium antimonate, zinc stannate, and zinc borate. Containing these flame-retardant additives further improves flame retardancy. More preferably, the flame-retardant additive is selected from one or more of the group consisting of antimony trioxide, antimony pentoxide, sodium antimonate, and potassium antimonate, and even more preferably, antimony trioxide and / or antimony pentoxide.

[0049] The amount of flame retardant additive relative to 100 parts by weight of the above condensate is preferably 1 to 100 parts by weight, more preferably 5 to 80 parts by weight, even more preferably 10 to 60 parts by weight, and even more preferably 20 to 50 parts by weight.

[0050] The resin composition for electrical insulation may further contain fibrous reinforcing materials. By including fibrous reinforcing materials, the strength of the molded article can be improved. Examples of fibrous reinforcing materials include glass fiber and carbon fiber.

[0051] When combined with fibrous reinforcing materials, the amount is not particularly limited. For example, relative to 100 parts by weight of polyethylene terephthalate, it can be 1 to 100 parts by weight, 5 to 80 parts by weight, or 10 to 60 parts by weight.

[0052] The resin composition for electrical insulation may further include inorganic fillers. Examples of inorganic fillers include metal silicates and titanium dioxide. Examples of metal silicates include magnesium silicate fillers such as talc, aluminum silicate fillers such as kaolin, aluminum-potassium silicate fillers such as mica, and calcium silicate fillers such as wollastonite. The addition of metal silicates can improve the resistance to tracking.

[0053] When combined with an inorganic filler (more preferably a metal silicate), the amount is not particularly limited. For example, relative to 100 parts by mass of alkylene terephthalate, it can be 1 to 100 parts by mass, 5 to 80 parts by mass, or 10 to 60 parts by mass.

[0054] The resin composition for electrical insulation may further contain various additives such as antioxidants, anti-drip agents, ultraviolet absorbers, crystal nucleating agents, crystallizing agents, and colorants (e.g., pigments).

[0055] Examples of antioxidants include phenolic antioxidants, phosphite antioxidants, and thioether antioxidants. When antioxidants are included, their amount is not particularly limited; for example, relative to 100 parts by weight of alkylene terephthalate, it can be 0.05 to 5 parts by weight, or 0.1 to 3 parts by weight.

[0056] Examples of anti-drip agents include polytetrafluoroethylene (PTFE). When an anti-drip agent is present, its amount is not particularly limited; for example, it can be 0.05 to 5 parts by weight or 0.1 to 3 parts by weight relative to 100 parts by weight of polyalkylene terephthalate.

[0057] There are no particular limitations on the preparation method of the resin composition for electrical insulation. For example, a method can be given by combining polyalkylene terephthalate and the above-mentioned condensate, as well as flame retardant additives, fibrous reinforcing materials, inorganic fillers and other additives as any components, and then performing melt mixing using a mixer such as an extruder.

[0058] The obtained electrical insulation resin composition can be molded in any molding method such as injection molding, extrusion molding, or vacuum molding to obtain the molded product.

[0059] The resin composition of this embodiment can be used for various electrical insulation applications. That is, molded articles made from the resin composition of this embodiment are preferably used as voltage-resistant components, such as sockets, coils, terminal blocks, plugs, switches, relay components, and circuit breaker components, due to their excellent flame retardancy and resistance to tracking. Therefore, the resin composition of this embodiment is also referred to as a resin composition for voltage-resistant components.

[0060] Furthermore, as described above, the electrical insulating resin composition of this embodiment can exhibit flame retardancy even when molded in a relatively thin layer. Therefore, it is also suitable for producing thin molded articles with a thickness of 0.4 to 1.6 mm, more preferably 0.5 to 1.0 mm, and even more preferably less than 1.0 mm. Even when producing such thin molded articles, both flame retardancy and resistance to tracking can be achieved.

[0061] Example

[0062] Hereinafter, embodiments and comparative examples will be described in detail together. However, the present invention is not limited to these embodiments.

[0063] Details of the raw materials used in the examples and comparative examples are described below.

[0064] [Flame retardant]

[0065] Flame retardant 1: Contains a compound represented by formula (1) above (where R is a compound represented by ...1 It is a condensation compound of tetrabromobisphenol A, cyanuric chloride, and tribromophenol (TBBA / CC / TBP) of -C(CH3)2-. The synthesis method is described below.

[0066] In a 5L four-necked glass flask equipped with a reflux flask, thermometer, dropping funnel, and stirrer, 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 dichloromethane were added. While stirring, the solution was cooled to 5°C, and the temperature of the reaction solution was maintained below 10°C. Simultaneously, 352.0g of a 50% (w / w) NaOH aqueous solution was slowly added dropwise through the dropping funnel. After the addition was complete, the solution was kept below 10°C for 30 minutes, and then the temperature was increased at a rate of 10°C / h until reflux was achieved. After maintaining the reflux temperature for 3 hours, the reaction solution was washed with water and then 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 98% by mass, with a bromine content of 60.0% by mass. The weight-average molecular weight (Mw) of this powder in THF solution, determined by GPC, was 3000. The chemical reaction formula is shown below.

[0067] [Chemistry 3]

[0068]

[0069] • Flame retardant 2: Comparative example, "SR-T20000" manufactured by Sakamoto Pharmaceutical Co., Ltd., brominated bisphenol A type epoxy resin, bromine content 52% by mass

[0070] • Flame retardant 3: Comparative example, "SAYTEX HP-7010" manufactured by Albamore Co., Ltd., brominated polystyrene, bromine content 68% by mass

[0071] • Flame retardant 4: Comparative example, "Pirogate (registered trademark) SR-460B" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., tribromophenol condensate, bromine content 62% by mass

[0072] [Polyalkyl terephthalate]

[0073] • PBT (GF 30%): Toray Industries, Inc.'s "Trecon 1101G-30" is glass fiber reinforced polybutylene terephthalate containing 30% by weight of glass fiber. The amounts in parentheses in the table are the proportions of glass fiber and the balance is the proportion of PBT.

[0074] [Flame retardant additives]

[0075] • Flame retardant additive 1: Antimony trioxide, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., "Pirogate (registered trademark) AN-800T"

[0076] • Flame retardant additive 2: Antimony pentoxide, manufactured by Nissan Chemical Co., Ltd., "NA-1030"

[0077] [Metal Silicates]

[0078] ·Metal silicate: talc, "Microtech #5000S" manufactured by Hayashi Kasei Co., Ltd.

[0079] [additive]

[0080] • Stabilizer 1: Hindered phenolic antioxidant, "Irganox 1010" manufactured by BASF Japan Co., Ltd.

[0081] • Stabilizer 2: Phosphite-based antioxidant, manufactured by BASF Japan Co., Ltd., "Irgafos 168"

[0082] • Anti-drip agent: "FluonPTFE CD145E (PTFE)" manufactured by AGC Co., Ltd.

[0083] [Evaluation Method]

[0084] • Flame retardancy: Tested using short strip test pieces (127mm long × 12.7mm wide × 0.8mm thick) according to UL-94. Flame retardancy is evaluated according to the UL-94 criteria, using four levels: V-0 (Excellent), V-1 (Good), V-2 (Average), and NR (Poor). V-2 and above are considered acceptable, while NR is outside the UL-94 criteria, indicating poor flame retardancy.

[0085] • Tracking resistance: Based on IEC 60112 of the International Electrotechnical Commission, a square plate test piece (50mm × 50mm × 3.2mm thickness) is used to determine and compare tracking resistance (CTI). Electrolyte solution A is dropped between the electrodes on the surface of the square plate test piece, and the voltage at which it can withstand 50 drops without causing tracking resistance is set as the CTI.

[0086] Those with a CTI of 600V or higher are rated "A" (very good tracking resistance), those with a CTI of less than 600V but more than 250V are rated "B" (good tracking resistance), and those with a CTI of less than 250V are rated "C" (poor tracking resistance).

[0087] [First Experimental Example]

[0088] The pellets were manufactured using a twin-screw extruder at 260°C and 200 rpm, according to the formulations (parts by weight) shown in Table 1 below. These pellets were then injection molded at a barrel temperature of 260°C and a die temperature of 80°C to produce test pieces. The obtained test pieces were used to evaluate flame retardancy and resistance to tracking.

[0089] [Table 1]

[0090]

[0091] The results are shown in Table 1. In the first experimental example, the minimum amount of flame retardant 1 to flame retardant 4 with a flame retardancy rating of V-0 was determined through preliminary tests. In each example and comparative example, the amount of flame retardant was set to this minimum amount, and the difference in resistance to tracking was evaluated under this condition. As a result, in Examples 1 to 3, which used flame retardant 1 (TBBA / CC / TBP) of this embodiment, the resistance to tracking was excellent. In contrast, in Comparative Examples 1 to 3, which used polymeric flame retardants 2 to 4, which were different from the flame retardants of this embodiment, the resistance to tracking was poor.

[0092] [Second Experimental Example]

[0093] According to the proportions (parts by mass) shown in Table 2 below, test pieces were prepared in the same manner as in the first experimental example. The obtained test pieces were used to evaluate flame retardancy and resistance to tracking. It should be noted that Example 1 in Table 2 is equivalent to Example 1 of the first experimental example.

[0094] [Table 2]

[0095]

[0096] The results are shown in Table 2. In the second experimental examples, in Comparative Examples 4 to 6, the amount of flame retardant was the same as in Example 1, and it was confirmed whether an effect that balances flame retardancy and resistance to tracking was achieved. In Comparative Examples 4 and 5, the amount of flame retardant was reduced compared to Comparative Examples 1 and 2, but the resistance to tracking was still poor. In addition, the flame retardancy was reduced compared to Example 1. In Comparative Example 6, similar to Comparative Example 3, although the flame retardancy was excellent, the resistance to tracking was poor. Thus, when using flame retardants 2 to 4, which are different from the flame retardants of this embodiment, it is impossible to balance flame retardancy and resistance to tracking.

[0097] In the second experimental example, as Examples 4-7 and Comparative Example 7, the amount of flame retardant in this embodiment was modified for evaluation. The results showed that, in Example 4, where the amount of flame retardant 1 was increased compared to Example 1 and the amount was 19 parts by weight relative to 100 parts by weight of PBT, the flame retardancy was excellent, and the resistance to tracking was also good, similar to Example 1. In Examples 5-7, where the amount of flame retardant 1 was reduced compared to Example 1 and the amount was set to 9-14.3 parts by weight relative to 100 parts by weight of PBT, the flame retardancy decreased compared to Example 1, but remained at a acceptable level (V-2), and the resistance to tracking was also good. In contrast, in Comparative Example 7, where the amount of flame retardant 1 was set to 21 parts by weight relative to 100 parts by weight of PBT, although the flame retardancy was excellent, the resistance to tracking was poor, and it was impossible to achieve both flame retardancy and resistance to tracking.

[0098] [Third Experimental Example]

[0099] According to the proportions (parts by mass) shown in Table 3 below, test pieces were prepared in the same manner as in the first experimental example. The flame retardancy and resistance to tracking were evaluated using the obtained test pieces. It should be noted that Example 1 in Table 3 is equivalent to Example 1 of the first experimental example.

[0100] [Table 3]

[0101]

[0102] The results are shown in Table 3. By incorporating metal silicate salts in Example 8, the tracking resistance can be improved while maintaining excellent flame retardancy compared to Example 1.

[0103] It should be noted that the various numerical ranges described in this specification can be arbitrarily combined with their respective upper and lower limits, and all combinations thereof are described in this specification as the preferred numerical ranges. Furthermore, the description of the numerical range "X~Y" refers to values ​​above X and below Y.

[0104] The foregoing has described several embodiments of the present invention, but these embodiments are given by way of example only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments, as well as their omissions, substitutions, and modifications, are included in the scope and spirit of the invention, and are also included in the scope of the invention as described in the claims and its equivalents.

Claims

1. A resin composition for electrical insulation, characterized in that, contain: Polyalkylene terephthalate; and A condensation of tetrabromobisphenol, cyanuric chloride, and tribromophenol The amount of the condensate is 9 to 19 parts by mass relative to 100 parts by mass of the polyalkylene terephthalate.

2. The resin composition for electrical insulation according to claim 1, wherein, The condensate contains a compound represented by the following general formula (1). [Chemistry 1] R in equation (1) 1 It represents -C(CH3)2- or -SO2-, and n represents a number greater than 1.

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

4. The resin composition for electrical insulation according to claim 3, wherein, The amount of the flame retardant additive is 1 to 100 parts by mass relative to 100 parts by mass of the condensate.

5. The electrical insulating resin composition according to claim 1 or 2, wherein, The polyalkylene terephthalate contains polybutylene terephthalate.

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