Flame retardant polyphenylene ether and process for producing the same

Abstract

To provide a flame-retardant polyphenylene ether having a low molecular weight, excellent in solubility in a solvent and exhibiting high flame retardancy.SOLUTION: A flame-retardant polyphenylene ether represented by the following general formula (1) and having a number average molecular weight of 1,000 to 10,000 in terms of standard polystyrene measured by a gel permeation chromatography method is used. (In the formula, R is absent or represents an alkylene group having 1 to 6 carbon atoms, - S -, or - SO2 -, R1 to R4 each independently represent hydrogen atoms, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and n represents an integer of 1 or more.). ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyphenylene ether having excellent flame retardancy and a method for producing the same. [Background technology]

[0002] Polyphenylene ether (PPE) has excellent dielectric properties (low dielectric constant and low dielectric dissipation factor) in the high-frequency band, and is therefore used as a resin material in electronic circuit boards and other applications that require low transmission loss. Crosslinked PPE, which has a low molecular weight, excellent solubility in solvents, and functional groups at both ends that can be chemically converted, is particularly popular. Resins used in electronic materials must be flame-retardant, so flame retardants are added to the resin. However, adding flame retardants can sometimes impair the physical properties of the resin, so there is a demand for PPE with even higher flame retardancy.

[0003] Patent Document 1 discloses a method for producing a halogen-containing flame-retardant polyphenylene ether by oxidative co-condensation of a 2,6-disubstituted phenol with a halogenated polyphenol in the presence of a catalyst. However, the obtained polyphenylene ether does not have a sufficient bromine content, which contributes to flame retardancy. Furthermore, the inventors of the present invention conducted follow-up experiments and found that the polyphenylene ether had low solubility in solvents due to its large molecular weight (see Comparative Example 1 in this specification).

[0004] Patent Document 2 discloses a method for producing a flame-retardant halogenated polyphenylene ether, which is characterized by reacting polyphenylene ether with a halogenated phenol. However, when the present inventors conducted follow-up experiments, they were unable to obtain a halogenated polyphenylene ether having a low molecular weight and a high bromine content (see Comparative Example 2 in this specification). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 51-600 [Patent Document 2] Japanese Patent Publication No. 51-8398 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally known flame-retardant polyphenylene ethers have problems in that their molecular weights are not controlled to be sufficiently low, resulting in low solubility in solvents and an insufficient bromine content, which contributes to flame retardancy.

[0007] The present invention has been made in view of the above-mentioned background art, and an object of the present invention is to provide a polyphenylene ether which has a low molecular weight, excellent solubility in solvents, and exhibits high flame retardancy. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have found that the following invention can solve the above problems, and have completed the present invention.

[0009] That is, the present invention relates to the following flame-retardant polyphenylene ether.

[0010] [1] A flame-retardant polyphenylene ether represented by the following general formula (1), characterized in that the number average molecular weight, measured by gel permeation chromatography in terms of standard polystyrene, is 1,000 to 10,000:

[0011] [ka] (In the formula, R is absent or represents an alkylene group having 1 to 6 carbon atoms, -S-, or -SO2-; R 1 ~R 4 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and n represents an integer of 1 or more. [2] The flame-retardant polyphenylene ether according to [1], which has a number average molecular weight of 1,000 to 5,000 in terms of standard polystyrene as measured by gel permeation chromatography.

[0012] [3] The flame-retardant polyphenylene ether according to [1] or [2], which has a bromine content of 5% by weight or more.

[0013] [4] The flame-retardant polyphenylene ether according to [1] or [2], characterized in that in general formula (1), R is a 2,2-propylene group and the bromine content is 5% by weight or more.

[0014] [5] The flame-retardant polyphenylene ether according to [1] or [2], which has a solubility in toluene at 20°C of 10% by weight or more.

[0015] [6] A method for producing the flame-retardant polyphenylene ether according to [1], characterized by reacting a compound represented by the following general formula (2) with a polyphenylene ether having a number average molecular weight of 5,000 to 30,000 and having a repeating unit represented by the following general formula (3) in the presence of a radical initiator and a solvent:

[0016] [ka] (In the formula, R is absent, or represents an alkylene group having 1 to 6 carbon atoms, -S-, or -SO2-.)

[0017] [ka] (In the formula, R 5 ~R 8 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. [7] The method according to [6], wherein the radical initiator is an organic peroxide.

[0018] [8] The production method according to [6] or [7], wherein the solvent is one or more solvents selected from the group consisting of aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, and ether solvents.

[0019] [9] The production method according to [6] or [7], wherein the amount of the compound represented by the general formula (2) is 1 to 200 parts by weight per 100 parts by weight of the compound represented by the general formula (3). [Effects of the Invention]

[0020] The flame-retardant polyphenylene ether of the present invention has a lower molecular weight and is excellent in solubility in solvents compared to conventionally known flame-retardant polyphenylene ethers, and is effective in ensuring high flame retardancy. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in more detail below.

[0022] One aspect of the present invention relates to a flame-retardant polyphenylene ether represented by the following general formula (1).

[0023] [ka] (In the formula, R is absent or represents an alkylene group having 1 to 6 carbon atoms, -S-, or -SO2-; R 1 ~R 4 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and n represents an integer of 1 or greater. In general formula (1), the alkylene group having 1 to 6 carbon atoms represented by R is not particularly limited, but examples thereof include a methylene group, an ethylene group, a 2,2-propylene group, a 2,2-butylene group, a hexadiene group, and a 1,1-cyclohexylene group.

[0024] In general formula (1), R is preferably an alkylene group having 1 to 3 carbon atoms, more preferably a 2,2-propylene group, in that the flame-retardant polyphenylene ether will have excellent heat resistance and other properties.

[0025] In general formula (1), R 1 ~R 4 The alkyl group having 1 to 6 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, and the like, and among these, a methyl group is preferred.

[0026] In general formula (1), R 1 ~R 4 The alkenyl group having 2 to 6 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include a vinyl group, an allyl group, an iso-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-pentenyl group, and a 1-hexenyl group. In the general formula (1), n ​​represents the average number of repeating units of the flame-retardant polyphenylene ether, and in the present invention, n represents an integer of 1 or more.

[0027] For example, when R is a 2,2-propylene group, R 1 , R 2 , is a methyl group, and R 3 , R 4 When , is a hydrogen atom and n is 20, the theoretical average molecular weight of the flame-retardant polyphenylene ether of the present invention is 2,947.

[0028] An example of the flame-retardant polyphenylene ether represented by general formula (1) is a compound having a structure represented by formula (5).

[0029] [ka] (In the formula, R is absent or represents an alkylene group having 1 to 6 carbon atoms, -S-, or -SO2-, and n represents an integer of 1 or greater.) In view of excellent solubility in solvents, the flame-retardant polyphenylene ether of the present invention preferably has a number average molecular weight, calculated as standard polystyrene, of 1,000 to 10,000, more preferably 1,000 to 8,000, and even more preferably 1,000 to 5,000, as measured by gel permeation chromatography.

[0030] The flame-retardant polyphenylene ether of the present invention has excellent solubility in solvents and has a weight average molecular weight (M w ) and number average molecular weight (M n ) ratio (M w / M n ) is preferably 1.0 to 4.0, more preferably 1.2 to 3.0, and even more preferably 1.5 to 2.5.

[0031] The flame-retardant polyphenylene ether of the present invention preferably has a bromine content of 5 to 30% by weight, more preferably 7 to 20% by weight, in that high flame retardancy is expected.

[0032] The flame-retardant polyphenylene ether of the present invention is not particularly limited, but as an example, it can be produced by reacting a compound represented by the following general formula (2) with a polyphenylene ether having a number average molecular weight of 5,000 to 30,000 and having a repeating unit represented by the following general formula (3) in the presence of a radical initiator and a solvent.

[0033] [ka] (In the formula, R is absent, or represents an alkylene group having 1 to 6 carbon atoms, -S-, or -SO2-.)

[0034] [ka] (In the formula, R 5 ~R 8 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. The compound represented by general formula (2) is not particularly limited, but examples thereof include tetrabromobisphenol A, tetrabromobisphenol F, bis(4'-hydroxy-3',5'-dibromophenyl)sulfone, etc. Among these, tetrabromobisphenol A is particularly preferred because of its excellent heat resistance and dielectric properties.

[0035] In the polyphenylene ether having a repeating unit represented by general formula (3), R 5 ~R 8 The alkyl group having 1 to 6 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, and the like, and among these, a methyl group is preferred.

[0036] In the polyphenylene ether having a repeating unit represented by general formula (3), R 5 ~R 8 The alkenyl group having 2 to 6 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include a vinyl group, an allyl group, an iso-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-pentenyl group, and a 1-hexenyl group.

[0037] An example of a polyphenylene ether having a repeating unit represented by general formula (3) is a compound having a repeating unit represented by formula (6).

[0038] [ka]

[0039] The polyphenylene ether having a repeating unit represented by general formula (3) preferably has a number average molecular weight of 5,000 to 30,000, more preferably 5,000 to 20,000, calculated in terms of standard polystyrene as measured by gel permeation chromatography.

[0040] In the production of the flame-retardant polyphenylene ether of the present invention, the radical initiator is not particularly limited, but examples thereof include peroxides (particularly organic peroxides). Specific examples include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(4,4,-di(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, and t-butylperoxy-2-ethylhexyl monocarbonate. , t-hexyl peroxybenzoate, cumene hydroperoxide, t-butyl peroxyacetate, 2,2-di(t-butylperoxy)butane, t-butyl peroxybenzoate, di-t-butyl peroxide, n-butyl 4,4-di-(t-butylperoxy)valerate, di(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butylcumyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and t-butyl hydroperoxide. Among these, t-butylperoxy-2-ethylhexanoate and t-butylperoxy-2-ethylhexyl monocarbonate are preferred in that they can produce flame-retardant polyphenylene ethers having a low molecular weight and a high bromine content.

[0041] In producing the flame-retardant polyphenylene ether of the present invention, the solvent is not particularly limited as long as it does not react with the substrate, and examples thereof include aromatic hydrocarbon solvents such as benzene, toluene, xylene, etc.; halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, etc.; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, butanol, etc.; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, methyl butyl ketone, methyl isobutyl ketone, etc.; ether solvents such as tetrahydrofuran, dioxane, etc. These solvents may be used alone or in combination of two or more. In the production of the flame-retardant polyphenylene ether of the present invention, the reaction temperature is not particularly limited, but is preferably in the range of 40°C to 160°C, and more preferably in the range of 50°C to 150°C.

[0042] In producing the flame-retardant polyphenylene ether of the present invention, the mixing ratio of the compound represented by the general formula (2) above to the compound represented by the general formula (3) above is preferably 1 to 200 parts by weight, more preferably 5 to 150 parts by weight, and even more preferably 10 to 100 parts by weight of the compound represented by the general formula (2) above, per 100 parts by weight of the compound represented by the general formula (3).

[0043] In the production of the flame-retardant polyphenylene ether of the present invention, the amount of the radical initiator used is preferably 0.1 to 100 parts by weight, more preferably 1 to 80 parts by weight, and even more preferably 2 to 50 parts by weight, relative to 100 parts by weight of the compound represented by the general formula (3).

[0044] In the production of the flame-retardant polyphenylene ether of the present invention, the amount of the solvent used is preferably 100 to 2,000 parts by weight, more preferably 150 to 1,500 parts by weight, and even more preferably 200 to 1,000 parts by weight, per 100 parts by weight of the compound represented by the general formula (3).

[0045] In the production of the flame-retardant polyphenylene ether of the present invention, after the reaction is completed, the resulting flame-retardant polyphenylene ether is recovered by any method and, if necessary, subjected to post-treatment such as washing. As a method for recovering the polymer from the reaction solution, known methods such as concentration and reprecipitation can be used. [Example]

[0046] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples in any way. Number average molecular weight (M) measured by gel permeation chromatography (GPC) n ) and weight average molecular weight (M w ) Measurement Equipment: Tosoh HLC-8320GPC Column: Tosoh TSKgel SuperAW2500, SuperAW3000 and SuperAW5000 connected Eluent: tetrahydrofuran Flow rate: 0.6mL / min Column temperature: 40℃ Detector: UV (254 nm) Calibration curve: A calibration curve was obtained using the following standard substances (all standard polystyrenes manufactured by Tosoh Corporation). ·"A-500" (weight average molecular weight = 589) ·"A-1000" (weight average molecular weight = 1,120) ·"A-2500" (weight average molecular weight = 3,120) ·"A-5000" (weight average molecular weight = 5,520) ·"F-1" (weight average molecular weight = 8,840) ·"F-2" (weight average molecular weight = 15,700) ·"F-4" (weight average molecular weight = 37,200) ·"F-10" (weight average molecular weight = 110,000) ·"F-20" (weight average molecular weight = 225,000)

[0047] <Measurement of bromine content by combustion-ion chromatography> Combustion device: AQF-2100H manufactured by Mitsubishi Chemical Analytech Sample amount: 4 mg Combustion temperature: 900 °C on the inlet side and 1000 °C on the outlet side Absorbent composition: 30 mg / L hydrogen peroxide solution Absorbent amount: 30 mL Ion chromatograph: IC-2010 manufactured by Tosoh Corporation Eluent: 7.5 mmol / L aqueous sodium hydrogen carbonate solution + 0.8 mmol / L aqueous sodium carbonate solution Detection: Conductivity Analysis column: TSKgel SuperIC-Anion HS Guard column: TSKguardcolumn SuperIC-A HS Column temperature: 40 °C Injection volume: 30 μL Flow rate: 1.5 mL / min Suppressor gel: TSKgel suppress IC-A

[0048] <Structure analysis by NMR> Device: JNM-EC 400YH manufactured by JEOL Ltd. Solvent: 1,1,2,2-tetrachloroethane-d2 In the flame-retardant polyphenylene ether represented by the general formula (1), the hydrogen on the brominated aromatic ring 1 H NMR peak is observed around 7.42 ppm and around 7.29 ppm.

[0049] <Measurement of glass transition temperature by differential scanning calorimetry (DSC)> Device: DSC 200 F3 manufactured by Netzsch Measurement conditions: Under a nitrogen atmosphere, the temperature was raised to 240 °C at a rate of 10 °C / min, then cooled to 25 °C at a rate of 40 °C / min, and then heated to 240 °C at a rate of 10 °C / min to measure the glass transition temperature (T g )

[0050] <Evaluation of solubility in toluene> 0.10 g of flame-retardant polyphenylene ether and 0.90 g of toluene (10 wt %) were placed in a 9 mL glass screw tube and mixed for 30 minutes using a stirrer and a magnetic stirrer at 20°C. After leaving the solution to stand for 24 hours, if the solution maintained its transparency it was rated as "Good", and if it became opaque or the presence of insoluble matter was confirmed it was rated as "Poor".

[0051] <Synthesis of flame-retardant polyphenylene ether> Example 1 In a 50 mL three-necked recovery flask equipped with a magnetic stirrer and a reflux condenser, 25 g of toluene (Kishida Chemical Co., Ltd.), 5.00 g of poly(2,6-dimethyl-1,4-phenylene ether) (BLD Pharmatech, M n Then, 4.00 g of tetrabromobisphenol A (manufactured by Tosoh Corporation, 7.35 mmol) was added and the mixture was heated to 90°C while stirring. At this temperature, a solution of 1.00 g of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, product name Perbutyl O, 4.62 mmol) dissolved in 5 g of toluene was added dropwise over 30 minutes. After the addition was completed, the mixture was stirred at 90°C for an additional 3 hours and then allowed to cool to room temperature. The resulting reaction solution was added to methanol (manufactured by Kishida Chemical Co., Ltd.), and the precipitated solid was filtered, washed with methanol, and then dried. A white solid flame-retardant polyphenylene ether (A) was obtained in a 60% yield.

[0052] The analytical results of the product are shown below. 1 H NMR (400MHz, tetrachloroethane-d2, ppm) δ=7.42(Ar-H),7.29(Ar-H),6.56(Ar-H),6.47(Ar-H),2.24-1.99(C H 3), 1.69-1.65(C H 3) M n =3,500,M w =6,700,M w / M n =1.9 Bromine content = 10.3% by weight T g =161℃

[0053] Example 2 The same procedure as in Example 1 was carried out, except that the amount of t-butylperoxy-2-ethylhexanoate used was 0.50 g and the amount of tetrabromobisphenol A used was 3.00 g, to obtain a white solid flame-retardant polyphenylene ether (B) in a yield of 66%.

[0054] The analytical results of the product are shown below. 1 H NMR (400MHz, tetrachloroethane-d2, ppm) δ=7.41(Ar-H),7.29(Ar-H),6.55(Ar-H),6.47(Ar-H),2.24-1.95(C H 3), 1.69-1.63(C H 3) M n =4,200,M w =7,900,M w / M n =1.9 Bromine content = 8.8% by weight

[0055] Example 3 In a 50 mL three-necked recovery flask equipped with a magnetic stirrer and a reflux condenser, 25 g of xylene (Kishida Chemical Co., Ltd.), 5.00 g of poly(2,6-dimethyl-1,4-phenylene ether) (BLD Pharmatech, M n Then, 3.00 g of tetrabromobisphenol A (manufactured by Tosoh, 5.52 mmol) was added and the mixture was heated to 120°C while stirring. At this temperature, a solution of 0.38 g of t-butylperoxy-2-ethylhexyl monocarbonate (manufactured by Sigma-Aldrich, product name LuperoxTBEC, 1.5 mmol) dissolved in 5 g of xylene was added dropwise over 30 minutes. After the addition was completed, the mixture was stirred at 120°C for an additional 3 hours and then allowed to cool to room temperature. The resulting reaction solution was added to methanol (manufactured by Kishida Chemical), and the precipitated solid was filtered, washed with methanol, and then dried. A white solid flame-retardant polyphenylene ether (C) was obtained in a yield of 34%.

[0056] The analytical results of the product are shown below. 1 H NMR (400MHz, tetrachloroethane-d2, ppm) δ=7.42(Ar-H),7.29(Ar-H),6.55(Ar-H),6.47(Ar-H),2.24-1.98(C H 3), 1.65-1.62(C H 3) M n =4,500,M w =8,500,M w / M n =1.9 Bromine content = 7.8% by weight

[0057] Comparative Example 1 Polyphenylene ethers were synthesized according to the method of Example 1 described in Patent Document 1 (Japanese Patent Laid-Open Publication No. 51-600), and a brown solid product (D) was obtained in a yield of 91%. The analytical results of the product are shown below. M n =27,000,M w =51,000,M w / M n =1.9 Bromine content = 4.9% by weight T g =200℃

[0058] Comparative Example 2 Polyphenylene ethers were synthesized according to the method of Example 4 described in JP-A-51-8398, and a white solid product (E) was obtained in a yield of 70%.

[0059] The analytical results of the product are shown below. M n =16,000,M w =39,000,M w / M n =2.4 Bromine content = 0.8% by weight The results obtained are shown in Table 1.

[0060] [Table 1]

[0061] From the above results, it is clear that the flame-retardant polyphenylene ether of the present invention has a lower molecular weight, is excellent in solubility in solvents, and has a higher bromine content than conventional polyphenylene ethers.

Claims

1. A flame-retardant polyphenylene ether represented by the following general formula (1), which has a number average molecular weight of 1,000 to 10,000 in terms of standard polystyrene as measured by gel permeation chromatography: 【Chemistry 1】 (wherein R is absent, an alkylene group having 1 to 6 carbon atoms, —S—, or —SO ２ - indicates R １ ~R ４ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and n represents an integer of 1 or more.

2. 2. The flame-retardant polyphenylene ether according to claim 1, which has a number average molecular weight of 1,000 to 5,000 in terms of standard polystyrene as measured by gel permeation chromatography.

3. 3. The flame-retardant polyphenylene ether according to claim 1, which has a bromine content of 5% by weight or more.

4. 3. The flame-retardant polyphenylene ether according to claim 1, wherein in general formula (1), R is a 2,2-propylene group and the bromine content is 5% by weight or more.

5. 3. The flame-retardant polyphenylene ether according to claim 1, which has a solubility in toluene at 20°C of 10% by weight or more.

6. 2. A method for producing a flame-retardant polyphenylene ether according to claim 1, comprising reacting a compound represented by the following general formula (2) with a polyphenylene ether having a number average molecular weight of 5,000 to 30,000 and having a repeating unit represented by the following general formula (3) in the presence of a radical initiator and a solvent: 【Chemistry 2】 (wherein R is absent, an alkylene group having 1 to 6 carbon atoms, —S—, or —SO ２ - indicates.) 【Transformation 3】 (In the formula, R ５ ~R ８ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms.

7. The method according to claim 6, wherein the radical initiator is an organic peroxide.

8. 8. The production method according to claim 6 or 7, wherein the solvent is one or more solvents selected from the group consisting of aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents, and ether solvents.

9. The method according to claim 6 or 7, wherein the compound represented by the general formula (2) is used in an amount of 1 to 200 parts by weight relative to 100 parts by weight of the compound represented by the general formula (3).

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