Application of a cyclotriphosphazene derivative in the preparation of flame retardant rubber

Abstract

The present invention relates to an application of a cyclotriphosphazene derivative in the preparation of flame-retardant rubber. The cyclotriphosphazene derivative is used as a flame retardant, and a mixed gel, an accelerator and a vulcanizing agent are used as raw materials, and the flame-retardant rubber is obtained by treatment. The mixed gel is 100 parts, the flame retardant cyclotriphosphazene derivative is 5 to 20 parts, the vulcanizing agent is 1-3 parts, and the accelerator CZ is 1-1.5 parts, preferably 20 parts of the flame retardant cyclotriphosphazene derivative, 2 parts of the vulcanizing agent, and 1.4 parts of the accelerator CZ. The flame-retardant rubber has good flame retardant properties, and the limiting oxygen index (LOI) can reach up to 26.0, which can effectively inhibit the combustion of rubber and improve the safety of natural rubber.

Description

Technical Field

[0001] The invention relates to the use of a cyclotriphosphazene derivative, in particular to the use of a cyclotriphosphazene derivative in the preparation of flame-retardant rubber. The cyclotriphosphazene derivative is used as a flame retardant for natural rubber and has excellent flame retardant properties. Background Art

[0002] PFPN has been widely used as a common flame retardant. In order to further improve the performance of flame retardant materials, some other functional groups can be introduced into the PFPN intermediate HFPN to improve its flame retardant properties.

[0003] Cyclotriphosphazene has many different types of derivatives. Among them, cyclotriphosphazene compounds containing benzene ring groups such as phenoxy or aniline have excellent heat and hydrolysis resistance, good chemical stability and optical properties, and exhibit high limiting oxygen index (LOI) and low smoke emission.

[0004] The flame retardant mechanism of cyclotriphosphazene derivatives containing phenoxy groups as flame retardants is that the phenoxy group will be dissociated first under high temperature conditions and further participate in the disproportionation reaction. In this process, the disproportionation product of the benzene ring structure will produce a quenching effect, thereby exerting a gas-phase flame retardant effect.

[0005] On the other hand, under the action of cyclotriphosphazene, the polymer material will decompose in advance, and the various active molecules produced by the cracking reaction of the cyclotriphosphazene skeleton at high temperature can react with the surrounding materials, accelerate the carbonization process of the polymer material, increase the residual carbon yield, and make more matrix components fixed in the condensed phase in the form of residual carbon. The formation of this residual carbon can effectively improve the flame retardant properties of the molecular material, thereby preventing the material from burning at high temperatures. Summary of the invention

[0006] In view of the above problems existing in the prior art, the purpose of the present invention is to provide an application of a cyclotriphosphazene derivative in the preparation of flame retardant rubber.

[0007] The present invention discloses an application of a cyclotriphosphazene derivative in the preparation of flame-retardant rubber. The structural formula of the cyclotriphosphazene derivative is shown in formula (I):

[0008]

[0009] In formula (I), H on the benzene ring may be substituted by a substituent R or not, and the substituent R is selected from alkyl, alkoxy or halogen; the substituent R is preferably 4-methyl, 4-ethyl, 4-methoxy, 4-fluoro or 3-methyl.

[0010] Furthermore, the present invention also defines the preparation method of the cyclotriphosphazene derivative as follows: in the presence of an acid binding agent, hexafluorocyclotriphosphazene and the compound represented by formula (II) are added to an organic solvent for substitution reaction to obtain the cyclotriphosphazene derivative represented by formula (I),

[0011]

[0012] Furthermore, the present invention also defines specific conditions of the preparation method, such as the organic solvent is a saturated alkane, preferably n-hexane; the molar ratio of hexafluorocyclotriphosphazene to the compound represented by formula (II) is 1:0.9-1.3, preferably 1:1.1; the acid binding agent is an alkali metal hydroxide or an alkali metal carbonate, preferably sodium hydroxide, potassium carbonate or sodium carbonate, and the most preferred is potassium carbonate; the temperature of the substitution reaction is 30-69°C, preferably 60°C; and the reaction time is 2-7h, preferably 6h.

[0013] Furthermore, the present invention also defines a flame retardant rubber with a flame retardant of the cyclotriphosphazene derivative of the present invention, which includes components of a mixed gel, a flame retardant cyclotriphosphazene derivative, an accelerator and a vulcanizer. Based on 100 parts of the mixed gel, the flame retardant cyclotriphosphazene derivative is 5 to 20 parts, the vulcanizer is 1 to 3 parts, and the accelerator CZ is 1 to 1.5 parts. Preferably, the flame retardant cyclotriphosphazene derivative is 20 parts, the vulcanizer is 2 parts, and the accelerator CZ is 1.4 parts.

[0014] Furthermore, the present invention also defines that the mixed gel includes the following components in parts by weight: 100 parts of natural rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 16 parts of carbon black N330, 24 parts of carbon black N660, 15 parts of calcium carbonate, 1 part of antioxidant 4020 and 1 part of microcrystalline sodium.

[0015] Furthermore, the present invention also limits the vulcanizing agent to sulfur.

[0016] The preferred six compound structural formulas defined in the present invention are as follows:

[0017]

[0018]

[0019] The method for preparing the flame retardant rubber of the present invention comprises two stages of rubber refining, and specifically comprises the following steps:

[0020] 1) Preparation of mixed rubber: feed materials according to the feed ratio, heat the internal mixer to 170°C, add 100 parts of natural rubber and plasticize for 2 minutes, then add 5 parts of zinc oxide, 2 parts of stearic acid, 16 parts of carbon black N330, 24 parts of carbon black N660, 15 parts of calcium carbonate, 1 part of antioxidant 4020, 1 part of microcrystalline sodium, mix for 7 minutes to prepare a mixed rubber, and extrude it into sheets on an open mixer for standby use;

[0021] 2) Preparation of flame retardant rubber: 100 parts of the mixed rubber from step 1) are added to an open mill, and 1-3 parts of a vulcanizing agent, 1-1.5 parts of an accelerator CZ and 5-20 parts of a cyclotriphosphazene derivative are added, and the mixture is passed through the mill for 6 times to mix evenly, and rectangular pieces are cut into pieces with a thickness of 2.5 mm for later use;

[0022] 3) Cut the rectangular sheet and put it into a mold, and vulcanize it with a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160° C., and a vulcanization time of 10 minutes to obtain a flame retardant rubber.

[0023] By adopting the above technology, the present invention has the following beneficial effects:

[0024] The present invention uses a limited method to prepare a cyclotriphosphazene derivative shown in formula (I) as a flame retardant for natural rubber, and obtains natural rubber by using a limited feed ratio and a limited preparation method with other components. The phenoxy group of the flame retardant first dissociates and undergoes a disproportionation reaction at high temperature, and the quenching effect of the phenoxy group and its disproportionation product produced thereby exerts a gas phase flame retardant effect, which can improve the flame retardancy of natural rubber, and the limiting oxygen index (LOI) can reach up to 26.0. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and technical effect of the present invention clearer, the present invention is further described in detail with examples. It should be understood that the examples described in this specification are only for explaining the present invention, not for limiting the present invention.

[0026] Example 1: Preparation of compound (1)

[0027]

[0028] In a 250mL three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 120mL of n-hexane, 20g of HFPN and 8.3g of phenol were added and stirred evenly, and then 12.2g of potassium carbonate, an acid binding agent, was added. The reaction temperature was raised to 60°C and reacted for 6 hours, then cooled to room temperature, and the reaction solution was washed twice with 200mL of water, and then washed twice with 30mL of sodium hydroxide (10wt%). The filtrate obtained by separating the organic phase was a crude product liquid of phenoxy pentafluorocyclotriphosphazene. The filtrate was distilled to obtain 15.9g of phenoxy pentafluorocyclotriphosphazene, and the molar yield was 84.7%.

[0029] 1 H NMR (400MHz, Chloroform-d) δ7.44(t,J=7.8Hz,2H),7.33(td,J=7.3,1.2Hz,1H),7.23(d,J=7.7Hz,2H).

[0030] HRMS(ESI+)m / z calculated for C6H5F5N3OP3([M+H]+):323.9638.Found:323.9642.

[0031] Example 2: Preparation of compound (2)

[0032]

[0033]

[0034] The preparation method is basically the same as Example 1, except that phenol is replaced by 4-methylphenol to obtain compound (2).

[0035] Colorless liquid (yield 83.9%); 1 H NMR(400MHz,Chloroform-d)δ7.22(d,J=8.3Hz,2H),7.11(dd,J=8.5,1.7Hz,2H),2.38(s,3H).HRMS(ESI+)m / z calculated for C7H7F5N3OP3([M+H] + ):337.9795.Found:337.9798.

[0036] Example 3: Preparation of compound (3)

[0037]

[0038] The preparation method is basically the same as Example 1, except that phenol is replaced by 4-ethylphenol to obtain compound (3).

[0039] Yellow liquid (yield 78.4%); 1 H NMR(400MHz,Chloroform-d)δ7.26–7.22(m,2H),7.16–7.11(m,2H),2.71–2.65(m,2H),1.26(t,J=7.6Hz,3H).HRMS(ESI+)m / z calculated for C8H9F5N3OP3([M+H] + ):351.9951.Found:351.9955.

[0040] Example 4: Preparation of compound (4)

[0041]

[0042] The preparation method is basically the same as Example 1, except that phenol is replaced by 4-methoxyphenol to obtain compound (4).

[0043] Colorless liquid (yield 46.7%); 1 H NMR(400MHz,Chloroform-d)δ7.19–7.11(m,2H),6.97–6.88(m,2H),3.83(s,3H).HRMS(ESI+)m / z calculated for C7H7F5N3O2P3([M+H] + ):353.9744.Found:353.9738.

[0044] Example 5: Preparation of compound (5)

[0045]

[0046] The preparation method is basically the same as Example 1, except that phenol is replaced by 4-fluorophenol to obtain compound (5).

[0047] Colorless liquid (yield 72.5%); 1 H NMR(400MHz,Chloroform-d)δ7.24–7.18(m,2H),7.15–7.09(m,2H).HRMS(ESI+)m / z calculated for C6H4F6N3OP3([M+H] + ):341.9544.Found:341.9547.

[0048] Example 6: Preparation of compound (6)

[0049]

[0050] Colorless liquid (yield 82.2%); 1H NMR (400MHz, Chloroform-d) δ7.33–7.28 (m, 1H), 7.13 (d, J=7.8Hz, 1H), 7.06–7.00 (m, 2H), 2.40 (s, 3H). HRMS (ESI+) m / z calculated for C14H15NO3 ([M+H]+): 337.9795. Found: 337.9798.

[0051] Example 7: Preparation of flame retardant rubber containing compound (1)

[0052] 1) Preparation of mixed rubber: Rubber was mixed in two stages, the internal mixer was heated to 170°C, 100 parts of natural rubber was added and plasticized for 2 minutes, and then 5 parts of zinc oxide, 2 parts of stearic acid, 16 parts of carbon black N330, 24 parts of carbon black N660, 15 parts of calcium carbonate, 1 part of antioxidant 4020, and 1 part of microcrystalline sodium were added, and mixed for 7 minutes to prepare a mixed rubber, which was extruded into sheets on an open mixer for standby use.

[0053] 2) Preparation of flame retardant rubber: Take 100 parts (by mass, the same below) of the mixed rubber from the previous step and add it to an open mill, and add 2 parts of sulfur, 1.4 parts of accelerator CZ and 20 parts of compound. Thinly pass through 6 times to mix evenly, and cut into rectangular pieces with a thickness of 2.5 mm for later use;

[0054] 3) Cut the rectangular sheet and put it into a mold, and vulcanize it with a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160° C., and a vulcanization time of 10 minutes to obtain a flame retardant rubber.

[0055] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.6.

[0056] Vertical burning test method: The vertical burning level is FV-2.

[0057] Example 8: Preparation of flame retardant rubber containing compound (2)

[0058] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0059] 1) Preparation of modified flame retardant rubber: 100 parts of the mixed rubber from the previous step were added to an open mill, and 2 parts of sulfur, 1.5 parts of accelerator CZ and 20 parts of compound (2) were added. Thinly pass through 6 times to mix evenly, and cut into rectangular pieces with a thickness of 2.5 mm for later use;

[0060] 3) Cut the rectangular sheet and put it into a mold, and vulcanize it with a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160° C., and a vulcanization time of 10 minutes to obtain a flame retardant rubber.

[0061] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.7.

[0062] Vertical burning test method: The vertical burning level is FV-2.

[0063] Example 9: Preparation of flame retardant rubber containing compound (3)

[0064] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0065] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step were added to an open mill, and 2 parts of sulfur, 1.5 parts of accelerator CZ and 20 parts of compound (3) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0066] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.9.

[0067] Vertical burning test method: The vertical burning level is FV-2.

[0068] Example 10: Preparation of flame retardant rubber containing compound (4)

[0069] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0070] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step was added to an open mill, and 2 parts of sulfur, 1.4 parts of accelerator CZ and 5 parts of compound (4) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0071] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 24.9.

[0072] Vertical burning test method: The vertical burning level is FV-2.

[0073] Example 11: Preparation of flame retardant rubber containing compound (4)

[0074] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0075] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber from the previous step were added to an open mill, and 2 parts of sulfur, 1 part of accelerator CZ and 20 parts of compound (4) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0076] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.1.

[0077] Vertical burning test method: The vertical burning level is FV-2.

[0078] Example 12: Preparation of flame retardant rubber containing compound (4)

[0079] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0080] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step was added to an open mill, and 2 parts of sulfur, 1.4 parts of accelerator CZ and 20 parts of compound (4) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0081] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 26.0.

[0082] Vertical burning test method: The vertical burning level is FV-2.

[0083] Example 13: Preparation of flame retardant rubber containing compound (5)

[0084] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0085] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step were added to an open mill, and 2 parts of sulfur, 1.4 parts of accelerator CZ and 20 parts of compound (5) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0086] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.8.

[0087] Vertical burning test method: The vertical burning level is FV-2.

[0088] Example 14: Preparation of flame retardant rubber containing compound (6)

[0089] The preparation of the mixed gel is basically the same as that of Example 5 and will not be repeated here.

[0090] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step were added to an open mill, and 2 parts of sulfur, 1.5 parts of accelerator CZ and 19 parts of compound (6) were added. The mixture was passed through a thin mill for 6 times to mix evenly, and rectangular pieces with a thickness of 2.5 mm were cut for standby use; the rectangular pieces were cut and placed in a mold, and vulcanized in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0091] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.6.

[0092] Vertical burning test method: The vertical burning level is FV-2.

[0093] Comparative Example 1: Preparation of flame-retardant rubber containing traditional flame retardant antimony trioxide The preparation of the mixed gel is basically the same as that of Example 5, and will not be repeated here.

[0094] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber from the previous step are added to an open mill, and 2 parts of sulfur, 1.4 parts of accelerator CZ and antimony trioxide are added, with the addition amount of antimony trioxide being 20 parts. Thinly pass through 6 times to mix evenly, and cut out rectangular pieces with a thickness of 2.5 mm for standby use; cut the rectangular pieces and put them into a mold, and vulcanize them in a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0095] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 23.1.

[0096] Vertical burning test method: The vertical burning level is FV-2.

[0097] Comparative Example 2: Preparation of flame retardant rubber containing traditional flame retardant decabromodiphenylethane The preparation of the mixed gel is basically the same as that of Example 5, and will not be repeated here.

[0098] Preparation of modified flame retardant rubber: 100 parts of the mixed rubber in the previous step are added to an open mill, and 2 parts of sulfur, 1.4 parts of accelerator CZ and decabromodiphenylethane are added, and the amount of decabromodiphenylethane added is 20 parts. Thinly pass 6 times to mix evenly, and cut out rectangular pieces with a thickness of 2.5 mm for standby use; cut the rectangular pieces and put them into a mold, and vulcanize them in a flat vulcanizer with a vulcanization pressure of 14 MPa, a vulcanization temperature of 160°C, and a vulcanization time of 10 minutes to obtain flame retardant rubber.

[0099] Limiting Oxygen Index (LOI) test method: The limiting oxygen index (LOI) reaches 25.8.

[0100] Vertical burning test method: The vertical burning level is FV-2.

[0101] It can be seen from the experimental data that the flame retardant rubber containing the flame retardant of the present invention has good flame retardant properties, and the limiting oxygen index (LOI) can reach up to 26.0. The flame retardant of the present invention can improve the flame retardancy of natural rubber, and the effect is better than that of traditional flame retardants such as antimony trioxide and decabromodiphenylethane.

Claims

1. A flame retardant rubber, characterized in that It includes a mixed gel, a flame retardant cyclotriphosphazene derivative, an accelerator and a vulcanizing agent. Based on 100 parts of the mixed gel, the flame retardant cyclotriphosphazene derivative comprises 5 to 20 parts, the vulcanizing agent comprises 1 to 3 parts, and the accelerator CZ comprises 1 to 1.5 parts. The structural formula of the cyclotriphosphazene derivative is shown in formula (I): （Ⅰ） ， In formula (I), the H on the benzene ring may be substituted by a substituent R or not, and the substituent R is selected from alkyl, alkoxy or halogen.

2. The flame retardant rubber according to claim 1, characterized in that Based on 100 parts of the mixed gel, there are 20 parts of the flame retardant cyclotriphosphazene derivative, 2 parts of the vulcanizing agent, and 1.4 parts of the accelerator CZ.

3. The flame retardant rubber according to claim 1, characterized in that The mixed gel comprises the following components in parts by weight: 100 parts of natural rubber, 5 parts of zinc oxide, 2 parts of stearic acid, 16 parts of carbon black N330, 24 parts of carbon black N660, 15 parts of calcium carbonate, 1 part of anti-aging agent 4020 and 1 part of microcrystalline sodium.

4. The flame retardant rubber according to any one of claims 1 to 3, characterized in that The vulcanizing agent is sulfur.

5. The flame retardant rubber according to claim 1, characterized in that The substituent R is 4-methyl, 4-ethyl, 4-methoxy, 4-fluoro or 3-methyl.

6. The flame retardant rubber according to claim 1, characterized in that The preparation method of the cyclotriphosphazene derivative is as follows: in the presence of an acid binding agent, hexafluorocyclotriphosphazene and a compound represented by formula (II) are added to an organic solvent for substitution reaction to obtain a cyclotriphosphazene derivative represented by formula (I). (Ⅱ)。 7. The flame retardant rubber according to claim 6, characterized in that The organic solvent is a saturated alkane; the molar ratio of hexafluorocyclotriphosphazene to the compound represented by formula (II) is 1: 0.9-1.

3.

8. The flame retardant rubber according to claim 6, characterized in that The acid binding agent is an alkali metal hydroxide or an alkali metal carbonate.

9. The flame retardant rubber according to claim 1, characterized in that The temperature of the substitution reaction is 30-69°C, and the reaction time is 2-7h.

10. A method for preparing the flame retardant rubber according to claim 1, characterized in that The steps include: 1) Preparation of mixed rubber: add materials according to the feed ratio, heat the internal mixer to 170°C, add natural rubber and plasticize for 2 minutes, then add zinc oxide, stearic acid, carbon black N330, carbon black N660, calcium carbonate, antioxidant 4020 and microcrystalline sodium, mix for 7 minutes to prepare mixed rubber, and extrude it into sheets on an open mixer for standby use; 2) Preparation of flame retardant rubber: Take the mixed rubber from step 1) and add it to an open mixer, and add the vulcanizing agent, accelerator CZ and cyclotriphosphazene derivative according to the feed ratio, pass it through the mixer for 6 times to mix evenly, and cut it into rectangular pieces with a thickness of 2.5 mm for later use; 3) Cut the rectangular sheet and put it into a mold, and vulcanize it with a flat vulcanizer at a vulcanization pressure of 14 MPa, a vulcanization temperature of 160° C., and a vulcanization time of 10 minutes to obtain a flame retardant rubber.

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