NOVEL COMPOUND, CROSSLINKING AGENT AND CROSSLINKED FLUOROELASTOMER

Abstract

The present invention provides a crosslinking agent which can improve crosslinked fluoroelastomer high-temperature vapor resistance and a crosslinked fluoroelastomer having improved high-temperature vapor resistance. The present invention provides a compound having a structure represented by the following formula (1) (in the formula, R.sup.1 to R.sup.6 are each a hydrogen atom, a substituent, or a leaving group, and two or more of R.sup.1 to R.sup.6 are leaving groups; R.sup.a to R.sup.c are each a hydrogen atom or a substituent; and n is an integer from 2 to 5).

##STR00001##

Claims

1. A compound having the structure represented by the following Formula (1): ##STR00023## wherein R.sup.1 to R.sup.6 are each a hydrogen atom, a substituent, or a leaving group, and two or more of R.sup.1 to R.sup.6 are leaving groups; R.sup.a to R.sup.c are each a hydrogen atom or a substituent; and n is an integer from 2 to 5.

2. The compound according to claim 1, being a compound represented by the following formula (2A): ##STR00024## wherein R.sup.1 to R.sup.6 and R.sup.1 to R.sup.16 are each a hydrogen atom, a substituent, or a leaving group, two or more of R.sup.1 to R.sup.6 are leaving groups, and at least two of R.sup.11 to R.sup.16 are leaving groups; and A.sup.1 is a single bond or a linking group.

3. The compound according to claim 2, being a compound represented by the following formula (2B): ##STR00025## wherein R.sup.1, R.sup.6, R.sup.11, and R.sup.16 are each a leaving group; and A.sup.1 is as in formula (2A).

4. The compound according to claim 2, wherein A.sup.1 is a single bond, —O—, —S—, a heteroatom-containing group, a linear alkene group, a branched alkene group, a cycloalkene group, a fluorinated alkene group, or an arylene group.

5. The compound according to claim 1, wherein the leaving group is a group selected from a halogen atom, a hydroxyl group, an alkoxy group, a carbonyl-containing group, a phosphorus-containing substituent, a sulfur-containing substituent, primary to tertiary amino group, a cyano group, and a nitro group.

6. A crosslinking agent containing the compound according to claim 1.

7. A composition containing a fluoroelastomer, a crosslinking initiator, and the crosslinking agent according to claim 6.

8. A crosslinked fluoroelastomer obtained by crosslinking the composition according to claim 7.

9. A method for producing a crosslinked fluoroelastomer, comprising a step for heating the composition according to claim 7 to react the fluoroelastomer with the crosslinking agent and a step for converting a cyclohexane ring derived from the crosslinking agent into an aromatic ring.

10. A crosslinked fluoroelastomer produced by the method in claim 9, wherein a gel fraction after being exposed to 330° C. saturated steam for 24 hours is 45% or more.

11. A crosslinked fluoroelastomer, wherein a gel fraction after being exposed to 330° C. saturated steam for 24 hours is 45% or more.

12. The crosslinked fluoroelastomer according to claim 11, wherein the crosslinked structure does not contain any unsaturated bonds other than those in aromatic rings.

13. A molded product obtained from the crosslinked fluoroelastomer according to claim 8.

14. The molded product according to claim 13, being a sealing material.

Description

EXAMPLES

[0087] Vapor Resistance Calculation Results of Crosslinked Structure Model

[0088] The activation energy required for the water molecules to react was found using molecular orbital calculation. The results are shown in Table 1. Calculation was performed using Gaussian 09W (Rev. C.01) and a basis set of B3LYP/6-31+G*. The reaction with vapor becomes more difficult as the activation energy increases, and it can be said that it is a crosslinked structure having high high-temperature vapor resistance. The crosslinked structure (i) that can be derived from the crosslinking agent of the present invention has high activation energy and excels in vapor resistance because it does not include unsaturated bonds other than those in aromatic rings. Meanwhile, the crosslinked structures (ii) and (iii) derived from conventional crosslinking agents have low activation energy and poor vapor resistance because they include unsaturated bonds that are weak against vapor such as the vinyl group.

TABLE-US-00001 TABLE 1 Table 1: Vapor Resistance Calculation Results of Crosslinked Structure Model Activation Energy Crosslinked Structure Model [kcal/mol] (i) [00011] 59 Present Invention (ii) [00012] 45 (iii) [00013] 35

Example 1

[Synthesis of Compound 1]

[0089] Compound 1 described below was synthesized. Note that commercially available reagents were used for both the compound and the catalyst.

##STR00014##

[0090] (1) Synthesis of Intermediate 1

[0091] Magnesium chips (1.10 g, 45.3 mmol) and diethyl ether (20 mL) were prepared in a 200 mL two mouth flask having an agitator installed in a nitrogen atmosphere. 4-Bromo-1-butene (5.43 g, 40.2 mmol) dissolved in diethyl ether (20 mL) was slowly added dropwise into this flask while being agitated at room temperature. This was then agitated for a further thirty minutes at room temperature.

[0092] The obtained solution (34 mL, 20.4 mmol) was prepared in a separate 100 mL two mouth flask in a nitrogen atmosphere and dodecafluorosuberic acid (1.57 g, 4.0 mmol) dissolved in diethyl ether (4 mL) was then slowly added dropwise into this flask while being agitated at room temperature. After dripping, this was agitated for 1.25 hours at 45° C., returned to room temperature, then agitated for 15 hours. After slowly adding 50% hydrochloric acid having ice added thereto, and the organic layer was extracted using diethyl ether (15 mL×three times). After the organic layer was washed using a saturated sodium hydrogen carbonate solution (20 mL×three times) and water (20 mL×three times), then dried using anhydrous sodium sulfate, a filtrate was concentrated under reduced pressure. The obtained concentrate was purified using silica gel chromatography to obtain 1.19 g of intermediate 1 below, being a diketone compound.

##STR00015##

[0093] (2) Synthesis of Intermediate 2

[0094] Magnesium chips (0.53 g, 21.9 mmol) and diethyl ether (10 mL) were prepared in a 50 mL two mouth flask having an agitator installed in a nitrogen atmosphere, and allyl bromide (2.43 g, 20.1 mmol) dissolved in diethyl ether (10 mL) was slowly added dropwise into this flask while being agitated at room temperature. This was then agitated for a further thirty minutes at room temperature.

[0095] The obtained solution (11 mL, 6.3 mmol) was prepared in a separate 30 mL two mouth flask in a nitrogen atmosphere and cooled to −78° C. Intermediate 1 (1.19 g) dissolved in diethyl ether (2 mL) was slowly added dropwise into this flask while being agitated at −78° C. After agitating for 1 hour, returning to room temperature, and adding a reaction liquid into 10% hydrochloric acid, the organic layer was extracted using diethyl ether (15 mL×three times). After the organic layer was dried using anhydrous sodium sulfate, a filtrate was concentrated under reduced pressure. The obtained concentrate was purified using silica gel chromatography to obtain 1.13 g of intermediate 2 below, being a diol compound.

##STR00016##

[0096] (3) Synthesis of Intermediate 3

[0097] Intermediate 2 (1.13 g, 2.05 mmol), dichloromethane (41 mL), and first generation Grubbs catalyst (0.086 g, 0.105 mmol) were prepared in a 100 mL two mouth flask having an agitator installed in a nitrogen atmosphere, and this was agitated for 21 hours at 50° C. After returning to room temperature, the reaction liquid was purified using silica gel chromatography to obtain 0.853 g of intermediate 3 below.

##STR00017##

[0098] A structure analysis was performed on the obtained compound using .sup.1H-NMR and .sup.19F-NMR (AVANCE II 400 made by BRUKER). The results are shown below.

[0099] .sup.1H-NMR (CDCI.sub.3, 400 MHz): δ=1.79 (td, J=25.30 Hz, 6.07 Hz, 2H), 1.90 to 2.08 (m, 2H), 1.97 (s, 2H), 2.09 to 2.37 (m, 6H), 2.57 (d, J=17, 41 Hz, 2H), 5.53 to 5.67 (m, 2H), 5.73 to 5.86 (m, 2H)

[0100] .sup.19F-NMR (CDCI.sub.3, CFCI.sub.3, 376 MHz): δ=−119.60 (d, J=8.70 Hz, 4F), −121.09 to −125.29 (m, 4F), −121.82 to −122.30 (m, 4F)

[0101] (4) Synthesis of Compound 1

[0102] Compound 1 (0.148 g, 0.3 mmol), N-bromosuccinimide (0.112 g, 0.63 mmol), azobisisobutyronitrile (AIBN: 0.0014 g, 0.009 mmol), and carbon tetrachloride (3 mL) were prepared in a 30 mL two mouth flask having an agitator installed in an argon atmosphere, and this was agitated for 2 hours at 80° C. After returning to room temperature, this was concentrated under reduced pressure, and the obtained concentrate was purified using silica gel chromatography to obtain compound 1.

[0103] It was confirmed that compound 1 was synthesized by .sup.1H-NMR, 1.sup.9F-NMR, and mass spectrometry (MS). The same is true of the compounds below.

Example 2

[0104] [Synthesis of Compound 2]

[0105] Compound 2 described below was synthesized.

##STR00018##

(In the formula, Me is the methyl group)

[0106] 1,4-cyclohexadiene (8.01 g, 100.0 mmol) and dichloromethane (250 mL) were prepared in a 500 mL two mouth flask having an agitator installed in a nitrogen atmosphere, meta-chloroperoxybenzoic acid (containing 23% water, 23.55 g, 105.1 mmol) was slowly added while agitating at 0° C., and this was agitated for 48 hours at room temperature. After agitating, a sodium carbonate solution (2.5 M, 100 mL) was added and agitated for 15 minutes at 0° C. Next, after increasing the temperature to room temperature, the organic layer was washed using a saturated sodium hydrogen carbonate solution (200 mL) and a 20% saline solution (100 mL×three times), then dried using anhydrous sodium sulfate, and a filtrate was then concentrated under reduced pressure to obtain 6.62 g of a colorless, transparent liquid of 1,2-epoxy-4-cyclohexene.

[0107] Next, the 1,2-epoxy-4-cyclohexene described above (8.63 g, 89.8 mmol), methanol (180 mL), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (0.509 g, 2.2 mmol) were prepared in a 500 mL two mouth flask having an agitator installed in a nitrogen atmosphere, and this was agitated for 17 hours at room temperature. After agitating and concentrating under reduced pressure, the obtained concentrate was purified using silica gel chromatography to obtain 8.43 g of light yellow oily 1-hydroxy-2-methoxy-4-cyclohexene.

[0108] Next, the 1-hydroxy-2-methoxy-4-cyclohexene described above (2.95 g, 22.9 mmol), acetonitrile (115 mL), potassium peroxymonosulfate (12.69 g, 20.6 mmol), and 2-iodo-5-nitro-sodium benzenesulfonate (0.804 g, 2.29 mmol) were prepared in a 500 mL two mouth flask having an agitator installed in a nitrogen atmosphere, and this was agitated for 14 hours at 70° C. After returning this to room temperature and removing the salt using a silica gel short column (diethyl ether), this was concentrated under reduced pressure. The concentrate was purified using silica gel chromatography to obtain 0.913 g of light yellow oily 2-methoxy-4-cyclohexene-1-one.

[0109] 1,6-diiodododecafluorohexane (0.111 g, 0.2 mmol) and diethyl ether (2.5 mL) were prepared in a 30 mL two mouth flask having an agitator installed in an argon atmosphere, ethyl magnesium bromide (3.0 M: diethyl ether solvent, 0.146 mL, 0.44 mmol) was added dropwise while agitating at −78° C., and this was agitated for one hour and a half at −78° C. Thereafter, 2-methoxy-4-cyclohexene-1-one (0.0555 g, 0.44 mmol) was dissolved in diethyl ether (1.0 mL) and added dropwise, and this was agitated for 18 hours. After adding a saturated ammonium chloride aqueous solution, this was returned to room temperature, organic material was extracted from the water layer using diethyl ether, and the organic layer was dried using anhydrous sodium sulfate. The anhydrous sodium sulfate was removed by filtration, and after the organic layer was concentrated under reduced pressure, the obtained concentrate was then purified using silica gel chromatography to obtain compound 2.

Example 3

[0110] [Synthesis of Compound 3]

[0111] Compound 3 described below was synthesized.

##STR00019##

[0112] Compound 3 was synthesized from compound 2 above in the following procedure.

[0113] Sodium hydride (0.072 g, 3 mmol) and tetrahydrofuran (7 mL) were prepared in a 30 mL two mouth flask having an agitator installed in an argon atmosphere, compound 2 (0.277 g, 0.5 mmol) was dissolved in tetrahydrofuran (2 mL) while agitating at 0° C. and added dropwise, and this was agitated for 30 minutes at 0° C. After dissolving iodomethane (0.426 g, 3 mmol) in tetrahydrofuran (1 mL) and adding dropwise, the temperature was increased to room temperature and this was agitated for 21 hours. The reaction solution was diluted using hexane, and after adding a saturated ammonium chloride aqueous solution, organic material was extracted from the water layer using hexane, and the organic layer was dried using anhydrous sodium sulfate. The anhydrous sodium sulfate was removed by filtration and concentrated under reduced pressure, and the obtained concentrate was then purified using silica gel chromatography to obtain compound 3.

Example 4

[0114] [Synthesis of Compound 4]

[0115] Compound 4 described below was synthesized.

##STR00020##

[0116] Compound 2 above (0.291 g, 0.5 mmol) and methylene chloride (5 mL) were prepared in a 30 mL two mouth flask having an agitator installed in an argon atmosphere, boron tribromide (1M: methylene chloride solvent, 5 mL, 5 mmol) was added, and this was agitated for 3 hours at room temperature. Ammonia water was added at 0° C. and this was agitated for 30 minutes. Organic material was extracted from the water layer using methylene chloride, and the organic layer was washed using a saturated saline solution and dried using anhydrous sodium sulfate. The anhydrous sodium sulfate was removed by filtration, and after the organic layer was concentrated under reduced pressure, the obtained concentrate was then purified using silica gel chromatography to obtain compound 4.

EXAMPLE

[0117] It was confirmed that the structure represented by Formula (1) of the present application forms the desired crosslinked structure in the following tests.

[0118] Compound 2A described below having the structure of compound 2 above was used as the crosslinking agent. Furthermore, because fluoroalkyl iodide (—CF.sub.2CF.sub.2I) is introduced on the crosslinking reaction site of fluoroelastomer, tridecafluoroiodide was used in tests instead of perfluoroelastomer. Both were made to react in the presence of a radical initiator, and compound 2B below was synthesized, having the cyclohexene ring of compound 2A converted to a cyclohexane ring. Thereafter, compounds 2C and 2C′ below were synthesized, having the cyclohexane ring of compound 2B converted to an aromatic ring by heat. Thus, it was confirmed that the crosslinking agent of the present application undergoes a crosslinking reaction with fluoroelastomer and then undergoes aromatization due to heating thereafter. Note that in example 2, the compound 2A can be synthesized using tridecafluoroiodide instead of 1,6-diiodododecafluorohexane.

##STR00021##

[0119] Compound 1 (0.444 g, 1.0 mmol), ethylene dichloride (3.3 mL), and tridecafluorohexyl iodide (1.326 g, 3.0 mmol) were prepared in a 20 mL two mouth flask having an agitator installed in an argon atmosphere, benzoyl peroxide (0.102 g, 0.30 mmol) was added and this was agitated for 24 hours at 90° C. After returning to room temperature, the obtained concentrate was purified using silica gel chromatography to obtain compound 2B.

[0120] Compound 2B (0.089 g, 0.10 mmol) and pyridine (1.0 mL) were prepared in a 20 mL two mouth flask having an agitator installed in an argon atmosphere, thionyl chloride (0.026 g, 0.22 mmol) was slowly added, and this was then agitated for 18 hours at room temperature. After diluting using ether and washing the organic layer using dilute hydrochloric acid, a sodium hydrogen carbonate aqueous solution, and pure water in this order, this was then dried using anhydrous sodium sulfate. The anhydrous sodium sulfate was removed by filtration, and after the organic layer was concentrated under reduced pressure, the obtained concentrate was then purified using silica gel chromatography to obtain compound 2C and compound 2C′.

[0121] [Structural Analysis of Compound 2B]

[0122] .sup.1H-NMR (CDCI.sub.3, 400 MHz): δ=1.70 to 3.59 (m, 9H), 3.59 to 4.09 (m, 1H), 4.21 to 4.82 (m, 1H)

[0123] .sup.19F-NMR (CDCI.sub.3, CFCI.sub.3, 376 MHz): δ=81.12 to 81.35 (m, 6F), 106.10 to 124.41 (m, 16F), 125.32 to 128.00 (m, 4F)

[0124] [Structural Analysis of Compound 2C]

[0125] .sup.1H-NMR (CDCI.sub.3, 400 MHz): δ=7.76 (s, 4H)

[0126] .sup.19F-NMR (CDCI.sub.3, CFCI.sub.3, 376 MHz): δ=−81.26 (t, J=19.50 Hz, 3F), −111.77 (t, J=28.46 Hz, 2F), −121.71 to −122.08 (m, 2F), −122.12 to −122.33 (m, 2F), −123.18 to 123.46 (m, 2F), −126.52 to −126.74 (m, 2F)

[0127] [Structural Analysis of Compound 2C′]

[0128] .sup.1H-NMR (CDCI.sub.3, 400 MHz): δ=7.70 (t. J=7.76 Hz, 1H), 7.82 (s, 2H), 7.84 (s, 1H)

[0129] .sup.19F-NMR (CDCI.sub.3, CFCI.sub.3, 376 MHz): δ=−81.49 (t, J=19.69 Hz, 3F), −111.78 (t, J=28.73 Hz, 2F), −121.81 to −122.18 (m, 2F), −122.37 to −122.68 (m, 2F), −123.23 to 123.59 (m, 2F), −126.67 to −126.92 (m, 2F)

Example 5 and Comparative Examples 1 and 2

[Synthesis of Compound 5]

[0130] Compound 5 described below was synthesized.

##STR00022##

[0131] Compound 4 above (0.080 g, 0.15 mmol), methylene chloride (15 mL), triethylamine (0.090 g, 0.9 mmol), and 4-dimethylaminopyridine (2 mg, 0.015 mmol) were prepared in a 30 mL two mouth flask having an agitator installed in an argon atmosphere, and this was cooled to 0° C. Trifluoromethanesulfonyl chloride (0.103 g, 0.9 mmol) was added dropwise thereto, and this was agitated for 20 hours at 40° C. The reaction vessel was returned to room temperature and the reaction was stopped using ammonia water. Organic material was extracted from the water layer using methylene chloride, and the organic layer was washed using a saturated saline solution and dried using anhydrous sodium sulfate. The anhydrous sodium sulfate was removed by filtration, and after the organic layer was concentrated under reduced pressure, the obtained concentrate was then purified using silica gel chromatography to obtain compound 5.

[Sample Manufacturing Method]

[0132] Each sample was prepared as in Table 2 below.

[0133] Each component of the added amounts shown in Table 2 were inserted in a pressure-resistant vessel and substituted with Ar. This was then left until the perfluoroelastomer (PFE 40z made by 3M) dissolved. The pressure-resistant vessel was heated to 100° C.×30 mins to crosslink FFKM. This was then heated at 130° C.×2 hrs in a vacuum oven to volatilize the solvent. This was then heated at 310° C.×4 hours in a nitrogen-substituted oven.

TABLE-US-00002 TABLE 2 Table 2 Example 5 Comparative Example 1 Comparative Example 2 Perfluoroelastomer 0.5 g 0.5 g 0.5 g Crosslinking Initiator (Benzoyl Peroxide) (NYPER 0.03 mmol 0.03 mmol 0.03 mmol BW made by NOF Corporation) Compound (5) 0.06 mmol Crosslinking Agent (d) of Patent No. 6374867 0.06 mmol Triallyl Isocyanurate 0.06 mmol (TAIC made by Shinryo) Solvent (Fluorinert FC-3283) 5 ml 5 ml 5 ml

[0134] [Vapor Resistance Evaluation]

[0135] The weight (A) of the sample created in the method above (crosslinked molded product) was measured and exposed to saturated steam at 330° C. for 24 hours. The vapor exposed sample was immersed in Fluorinert FC-3283 at room temperature for 72 hours. The sample remaining as solid content after soaking was removed and heated at 130° C.×2 hrs in a vacuum oven to volatilize the solvent. The weight (B) after drying was measured, and the gel fraction was calculated using the following formula. The results are shown in Table 3.

Gel fraction=mass (B)/mass (A)×100

TABLE-US-00003 TABLE 3 Table 3 Gel Fraction Example 5 50% Comparative Example 1 30% Comparative Example 2  0%

INDUSTRIAL APPLICABILITY

[0136] The compound of the present invention can be used as the crosslinking agent of a fluoroelastomer. The crosslinked fluoroelastomer of the present invention may be used as a sealing material (O ring, etc.) that demands chemical resistance and high-temperature vapor resistance such as in power generation, semiconductor devices, and chemical plants.