Rubber flame retardant additive and rubber composition and preparation method thereof

Abstract

The invention discloses a rubber flame retardant additive and a rubber composition and a preparation method thereof. The rubber flame retardant additive can be used in combination with an aluminum hydroxide flame retardant to achieve uniform dispersion of the aluminum hydroxide flame retardant, improve the thermal stability and flame retardant efficiency of the flame retardant, reduce the hygroscopicity of the flame retardant, and achieve one-step rubber refining of the rubber containing the aluminum hydroxide flame retardant, thereby reducing the complexity of the process and improving the rubber performance. The preparation method of the rubber flame retardant additive is simple, easy to operate, and has high universality. It can share organic synthesis instruments and equipment, and the equipment has high versatility. It has good market application value in the rubber industry.

Description

Technical Field

[0001] The present invention relates to the field of rubber materials, in particular to a rubber flame retardant additive adapted to an aluminum hydroxide flame retardant, a rubber composition using the rubber flame retardant additive, and preparation methods thereof. Background Art

[0002] Currently, commercially available rubber flame retardants primarily fall into five categories: halogen-containing flame retardants, phosphorus-based flame retardants, nitrogen-containing flame retardants, composite flame retardants, and inorganic flame retardants. While these flame retardants can improve the fire resistance of rubber and its products, they can also lead to a decrease in the rubber's physical properties and fatigue life. Analysis reveals that commercially available flame retardants are primarily dispersed in rubber through mechanical mixing, a physical process that can lead to uneven dispersion within the rubber matrix, resulting in stress concentration and, inevitably, a decrease in the rubber's mechanical and fatigue properties.

[0003] In the field of rubber fire safety, aluminum hydroxide is a widely used physical additive flame retardant due to its non-toxicity, environmental friendliness, and low price. However, aluminum hydroxide currently still has the following disadvantages: 1. A large amount of aluminum hydroxide is usually required to achieve the desired flame retardant effect, which can significantly increase the volume of the rubber material, leading to increased density, decreased mechanical properties, and poor processing flowability; 2. During the mixing process, there is a problem of difficulty in feeding the material, resulting in long processing times and difficulty in uniform dispersion; 3. It has a certain degree of hygroscopicity and easily absorbs moisture in a high-humidity environment, which has a certain impact on the quality stability of rubber products. Summary of the Invention

[0004] The present invention provides a rubber flame retardant additive, a rubber composition containing the same, and a preparation method thereof, in order to solve the technical problems existing in the prior art mentioned in the background art.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A rubber flame retardant additive, whose chemical structure is shown in Formula 1:

[0007] .

[0008] The design idea of ​​the above technical solution is that the rubber flame retardant additive with the above molecular structure can assist the use of rubber flame retardants, especially aluminum hydroxide rubber flame retardants in rubber. The rubber flame retardant additive of the present invention contains multifunctional groups such as siloxane, benzene ring, imidazole, etc., among which siloxane can significantly improve the dispersion of aluminum hydroxide flame retardant in the rubber matrix, benzene ring can improve the thermal stability and flame retardant efficiency of aluminum hydroxide flame retardant, and imidazole can absorb free radicals, thereby improving the aging resistance of rubber products; compared with the technical solution commonly used in the prior art of chemically modifying aluminum hydroxide and then adding the modified aluminum hydroxide to the rubber mixing equipment, with the assistance of the rubber flame retardant additive of the present invention, the aluminum hydroxide flame retardant additive can be directly added to the rubber mixing equipment, and the chemical reaction is achieved by high-temperature hot refining, thereby realizing one-step rubber mixing and simplifying the process. In addition, the flame retardant additive is a hydrophobic substance that can reduce the hygroscopicity of aluminum hydroxide.

[0009] Based on the same technical concept, the present invention also provides a method for preparing a rubber flame retardant additive according to the above technical solution, wherein the rubber flame retardant additive is prepared by reacting a substrate S1 and a substrate S2;

[0010] The chemical structural formula of the substrate S1 is shown in Formula S1:

[0011] ;

[0012] The chemical structural formula of the substrate S2 is shown in Formula S2:

[0013] ;

[0014] In the formula, R is an alkane group, Y is one of methyl, ethyl and propyl groups, X is one of fluorine, chlorine, bromine and iodine, and 1≤n≤12.

[0015] As a further preferred embodiment of the above technical solution, the preparation method of the rubber flame retardant additive comprises the following steps:

[0016] Substrate S1 and substrate S2 are placed in a reaction container, and an amine base and an organic solvent are added. The temperature is raised under a protective atmosphere to react until the reaction is complete. After the reaction is completed, the solvent is concentrated to obtain the rubber flame retardant additive.

[0017] As a further preferred embodiment of the above technical solution, the reaction temperature of the temperature-raising reaction is 60-120° C., and the reaction time is 12-48 hours.

[0018] As a further preferred embodiment of the above technical solution, the mass ratio of the substrate S1, substrate S2 and amine base is 1:(1-2):(0.2-2).

[0019] As a further preferred embodiment of the above technical solution, the amine base includes at least one of ethylenediamine, dimethylethylenediamine, tetramethylethylenediamine, triethylenetetramine and triethylenediamine; and the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0020] Based on the same technical concept, the present invention also provides a rubber composition comprising a rubber matrix, a flame retardant and a flame retardant additive, wherein the flame retardant is an aluminum hydroxide flame retardant, and the flame retardant additive is the rubber flame retardant additive described in the above technical solution or the rubber flame retardant additive prepared by the preparation method described in the above technical solution.

[0021] As a further preferred embodiment of the above technical solution, the rubber composition includes the following components in parts by mass:

[0022] 100 parts of rubber matrix, 2 to 5 parts of vulcanization accelerator, 40 to 60 parts of aluminum hydroxide flame retardant and 1 to 3 parts of rubber flame retardant additive.

[0023] As a further preferred embodiment of the above technical solution, the rubber composition further includes additives, which include 3 to 10 parts by mass of zinc oxide, 1 to 2 parts by mass of stearic acid, 3 to 10 parts by mass of antioxidant, 10 to 30 parts by mass of carbon black and 10 to 30 parts by mass of white carbon black.

[0024] Based on the same technical concept, the present invention also provides a method for preparing the rubber composition described in the above technical solution, comprising the following steps:

[0025] (1) Add the rubber matrix to a general rubber mixing equipment, add and plasticize at 90-110°C for 3-5 minutes; then add aluminum hydroxide flame retardant, keep mixing at 90-110°C for 3-5 minutes; then add the rubber flame retardant additive, heat to 140-160°C, mix for 3-5 minutes, cool to below 110°C, add the vulcanization accelerator, and continue mixing for 3-5 minutes to obtain a rubber mixture;

[0026] (2) vulcanizing the rubber mix to obtain the rubber composition.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention designs a synthesis of a rubber flame retardant additive and its application in rubber. The rubber flame retardant additive can be used in combination with an aluminum hydroxide flame retardant to achieve uniform dispersion of the aluminum hydroxide flame retardant, improve the thermal stability and flame retardant efficiency of the flame retardant, reduce the hygroscopicity of the flame retardant, and realize a one-step rubber refining process of rubber containing the aluminum hydroxide flame retardant, thereby reducing the complexity of the process and improving the performance of the rubber.

[0029] (2) The preparation method of the rubber flame retardant additive of the present invention is simple, easy to operate, and has high universality. It can share organic synthesis instruments and equipment, and the equipment has high versatility. It has good market application value in the rubber industry.

[0030] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 The rubber flame retardant additive and reaction substrate S1 of Example 1 and the physical picture;

[0033] Figure 2 This is the nuclear magnetic spectrum of the rubber flame retardant additive of Example 1;

[0034] Figure 3 This is the TGA test chart of the vulcanized rubber of Example 1. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0036] Example 1:

[0037] The rubber flame retardant additive of this embodiment has a chemical structural formula as shown in Formula 1: .

[0038] The rubber flame retardant additive of this embodiment is prepared from triphenylimidazole and 3-chloropropyltriethoxysilane, and the specific preparation method includes the following steps:

[0039] Triphenylimidazole (0.1 mol, 29.6 g) and 3-chloropropyltriethoxysilane (0.12 mol, 28.9 g) were placed in a reaction vessel, triethylamine (0.03 mol, 3.0 g) was added, and then the organic solvent DMF (10 mol, 771 mL) was added. The mixture was purged with nitrogen for 40 minutes and stirred at 80°C under a nitrogen atmosphere for 24 hours. After the reaction was completed, the solvent was concentrated and dried under vacuum to obtain the rubber flame retardant additive (named TIMI) of this example.

[0040] The composition of the vulcanized rubber 1# in this embodiment is shown in Table 1, and the preparation method is as follows:

[0041] (1) Add natural rubber to a general rubber mixing equipment, add a chemical peptizer and mix for 5 minutes at a temperature of 100°C;

[0042] (2) Add zinc oxide, stearic acid, antioxidant, aluminum hydroxide, carbon black, and white carbon black, and mix at 100°C for 5 minutes;

[0043] (3) Add aluminum hydroxide flame retardant additive TIMI, heat to 150°C, and mix for 5 minutes;

[0044] (4) Cool down to 90℃, add sulfur and vulcanization accelerator CBS, mix for 5 minutes, pass through the open mill 5 times or make triangle bags 5 times, and then take off the sheet to obtain the mixed rubber No. 1;

[0045] (5) After the rubber mix obtained in step (4) was left to stand for 16 hours, vulcanized rubber 1# was obtained according to the vulcanization conditions of 150°C, 15 minutes and 20 MPa. The vulcanization curve is as follows: Figure 1 shown.

[0046] Comparative Example 1:

[0047] The vulcanized rubber 2# of this comparative example has a component formula as shown in Table 1 and is prepared as follows:

[0048] (1) Add natural rubber to a general rubber mixing equipment, add a chemical peptizer and mix for 5 minutes at a temperature of 100°C;

[0049] (2) Add zinc oxide, stearic acid, antioxidant, aluminum hydroxide, carbon black, and white carbon black, and mix at 100°C for 5 minutes;

[0050] (3) Cool down to 90℃, add sulfur and vulcanization accelerator CBS, mix for 5 minutes, pass through the open mill 5 times or make triangle bags 5 times, and then take off the sheet to obtain the mixed rubber 2#;

[0051] (4) After the rubber mix obtained in step (3) was left to stand for 16 hours, vulcanized rubber 2# was obtained according to the vulcanization conditions of 150°C, 15 minutes and 20 MPa. The vulcanization curve is shown in FIG. Figure 1 As shown. Figure 1 It can be seen that the addition of aluminum hydroxide flame retardant additive TIMI prolongs TS2 and improves the safety of rubber processing operations. At the same time, the MH value is also improved. It can be inferred that the crosslinking density and modulus of 1# rubber compound with TIMI added are higher than those of 2#.

[0052] RPA was used to test the Payne effect of 1# and 2# rubber compounds. The results are as follows: Figure 2 As shown, from Figure 2It can be seen that when tested at 70°C, the G' of the 2# compound is larger under small strain. As the strain increases, G' decreases rapidly, and ∆G' is 234.6MPa, which indicates that the compatibility between aluminum hydroxide and rubber is poor and the Payne effect is larger; the ∆G' of the rubber compound with 2 parts of aluminum hydroxide flame retardant additive TIMI is 156.75MPa, which indicates that the Payne effect between aluminum hydroxide and rubber is weakened, and TIMI improves the dispersion between aluminum hydroxide and rubber, weakening the Payne effect.

[0053] The thermal stability of 1# and 2# rubber compounds was tested by TGA. The test results are as follows: Figure 3 As shown. In the rubber compound without the addition of aluminum hydroxide flame retardant additive TIMI, the temperature at which aluminum hydroxide completely loses weight to become aluminum oxide is 323°C. In the rubber compound with the addition of aluminum hydroxide flame retardant additive TIMI, the temperature at which aluminum hydroxide completely loses weight to become aluminum oxide is 346°C. This shows that the addition of TIMI improves the thermal stability of aluminum hydroxide to a certain extent.

[0054] The water contact angle tester was used to test the 1# and 2# rubber compounds. The water contact angle of the 2# rubber compound was 7°, showing strong hydrophilicity, while the water contact angle of the 1# rubber compound was 140°, showing strong hydrophobicity.

[0055] Table 2 shows the physical and flame retardant properties of vulcanizates 1# and 2#. Compared to vulcanizate 2#, vulcanizate 1#, which incorporates the aluminum hydroxide flame retardant additive TIMI, exhibits significant improvements in tensile strength, 300% modulus, and oxidative aging resistance. This demonstrates that the addition of TIMI improves the physical and aging properties of the rubber compound. The heat release rate and maximum smoke density of vulcanizate 1# are significantly reduced, indicating that the addition of TIMI enhances the flame retardant efficiency of the aluminum hydroxide, thereby improving the flame retardant properties of the rubber compound.

[0056] Table 1 Rubber formulations of Example 1 and Comparative Example 1 (numbers in the table are parts by mass)

[0057]

[0058] Table 2 Physical and flame retardant properties of vulcanized rubber

[0059]

[0060] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. The above are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and conversions obtained without departing from the technical concept of the present invention should also be regarded as the scope of protection of the present invention.

Claims

1. A rubber flame retardant additive, characterized in that: The chemical structural formula of the rubber flame retardant additive is shown in Formula 1: ； R is an alkane group, Y is one of methyl, ethyl and propyl groups, and 1≤n≤12.

2. A method for preparing the rubber flame retardant additive according to claim 1, characterized in that: The rubber flame retardant additive is prepared by reacting substrate S1 and substrate S2; The chemical structural formula of the substrate S1 is shown in Formula S1: ； The chemical structural formula of the substrate S2 is shown in Formula S2: ； In the formula, R is an alkane group, Y is one of methyl, ethyl and propyl groups, X is one of fluorine, chlorine, bromine and iodine, and 1≤n≤12.

3. The method for preparing a rubber flame retardant additive according to claim 2, wherein: The following steps are involved: Substrate S1 and substrate S2 are placed in a reaction container, and an amine base and an organic solvent are added. The temperature is raised under a protective atmosphere to react until the reaction is complete. After the reaction is completed, the solvent is concentrated to obtain the rubber flame retardant additive.

4. The method for preparing a rubber flame retardant additive according to claim 3, characterized in that: The reaction temperature of the temperature-raising reaction is 60-120° C., and the reaction time is 12-48 hours.

5. The method for preparing a rubber flame retardant additive according to claim 3, characterized in that: The mass ratio of the substrate S1, substrate S2 and amine base is 1: (1-2): (0.2-2).

6. The method for preparing a rubber flame retardant additive according to claim 3, characterized in that: The amine base is selected from at least one of ethylenediamine, dimethylethylenediamine, tetramethylethylenediamine, triethylenetetramine and triethylenediamine; and the organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

7. A rubber composition, characterized in that The invention comprises a rubber matrix, a flame retardant and a flame retardant auxiliary agent, wherein the flame retardant is an aluminum hydroxide flame retardant, and the flame retardant auxiliary agent is the rubber flame retardant auxiliary agent according to claim 1 or the rubber flame retardant auxiliary agent prepared by the preparation method according to any one of claims 2 to 6.

8. The rubber composition according to claim 7, characterized in that The composition comprises the following components in parts by weight: 100 parts of rubber matrix, 2 to 5 parts of vulcanization accelerator, 40 to 60 parts of aluminum hydroxide flame retardant and 1 to 3 parts of rubber flame retardant additive.

9. The rubber composition according to claim 8, characterized in that The invention also includes auxiliary agents, which include 3 to 10 parts by mass of zinc oxide, 1 to 2 parts by mass of stearic acid, 3 to 10 parts by mass of an antioxidant, 10 to 30 parts by mass of carbon black and 10 to 30 parts by mass of white carbon black.

10. A method for preparing the rubber composition according to claim 8 or 9, characterized in that: The following steps are involved: (1) Add the rubber matrix to a general rubber mixing equipment, add and plasticize at 90-110°C for 3-5 minutes; then add aluminum hydroxide flame retardant, keep mixing at 90-110°C for 3-5 minutes; then add the rubber flame retardant additive, heat to 140-160°C, mix for 3-5 minutes, cool to below 110°C, add the vulcanization accelerator, and continue mixing for 3-5 minutes to obtain a rubber mixture; (2) vulcanizing the rubber mix to obtain the rubber composition.

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