Phosphorus and nitrogen-containing biomolecular modified inorganic materials, flame retardants, and flame-retardant rubbers and their manufacturing methods

Abstract

A phosphorus-nitrogen-containing biomolecularly modified inorganic flame retardant, flame-retardant rubber, and its preparation method are disclosed, belonging to the field of flame-retardant rubber materials. This phosphorus-nitrogen-containing biomolecularly modified inorganic flame retardant is an adenosine phosphate-nitrogen-based flame retardant or a mixture of inorganic materials and adenosine phosphate-nitrogen-based flame retardants; by mass ratio, the adenosine phosphate-nitrogen-based flame retardant : inorganic materials = (5-20):(20-25). The selected adenosine phosphate is widely available, environmentally friendly, and renewable. The nitrogen-based flame retardant decomposes endothermically and generates non-flammable gases, thus diluting the oxygen concentration of combustible materials. The selected inorganic materials have decomposition temperatures much higher than the rubber's own decomposition temperature, improving the flame-retardant properties of the matrix. Simultaneously, they exhibit good biocompatibility with latex. The ball-milled inorganic materials have reduced particle size and thinner lamellar layers, enhancing their mechanical properties when dispersed in the matrix. The combined effect improves the flame retardancy of natural rubber without affecting its mechanical properties and thermal stability.

Description

Technical Field

[0001] This invention relates to a phosphorus-nitrogen-containing biomolecule-modified inorganic flame retardant, flame retardant rubber, and its preparation method, belonging to the technical field of flame retardant rubber materials. Background Technology

[0002] Rubber is used in all aspects of people's lives and production. There are many types of rubber, such as natural rubber, styrene-butadiene rubber, ethylene-propylene rubber, and butadiene rubber. However, rubber itself is highly flammable, and its combustion produces a large amount of gases that affect humans and the environment. Therefore, the need for flame retardant rubber is becoming increasingly urgent.

[0003] To address the poor flame retardancy of existing rubber, traditional techniques involve adding halogens to the rubber because halogen-containing rubbers have a higher limiting oxygen index (LOI) than halogen-free rubbers. However, halogens produce toxic and harmful gases when burned, endangering human life and damaging the ecological environment. Ammonium polyphosphate (APP)-based flame retardants are more environmentally friendly than halogens and produce non-flammable gases when burned, diluting the oxygen concentration of combustibles. Among the developed flame retardants, APP-based flame retardants (such as ammonium polyphosphate / pentaerythritol and ammonium polyphosphate / pentaerythritol / melamine) and expandable graphite are among the more noteworthy types of flame retardants and have received extensive research. Although these studies have shown that they can improve the flame retardancy of natural rubber, the poor compatibility between these two flame retardants and natural rubber leads to a decrease in mechanical properties and makes the rubber more susceptible to thermal degradation, reducing its thermal stability. Summary of the Invention

[0004] To address the poor flame retardancy of rubber, this invention provides a phosphorus-nitrogen-containing biomolecularly modified inorganic flame retardant, flame-retardant rubber, and its preparation method. The selected adenosine-based phosphate material is widely available, environmentally friendly, and renewable. The nitrogen-based flame retardant decomposes endothermically, generating non-flammable gases that dilute the oxygen concentration of combustible materials. The selected inorganic material has a decomposition temperature much higher than that of rubber itself, improving the flame retardant properties of the matrix. Simultaneously, it exhibits excellent biocompatibility with latex. Ball milling reduces the particle size and thins the lamellar layers, dispersing them within the matrix and enhancing its mechanical properties. Based on these advantages, adding a certain amount of flame retardant can improve the flame retardancy of natural rubber without affecting its mechanical properties and thermal stability.

[0005] The present invention provides a phosphorus-nitrogen biomolecular modified inorganic material flame retardant, which is an adenosine phosphate-nitrogen flame retardant or a mixture of inorganic material and adenosine phosphate-nitrogen flame retardant; when the phosphorus-nitrogen biomolecular modified inorganic material flame retardant is a mixture of inorganic material and adenosine triphosphate-nitrogen flame retardant, the mass ratio of adenosine phosphate-nitrogen flame retardant to inorganic material is (5-20):(20-25).

[0006] The aforementioned adenosine-based phosphoric acid-nitrogen flame retardant has a molar ratio of adenosine triphosphate:nitrogen flame retardant = 1:3 and adenosine diphosphate:nitrogen flame retardant = 1:2.

[0007] The nitrogen-based flame retardant is selected from melamine and / or dihydrodiamine.

[0008] The adenosine phosphates mentioned are selected from adenosine triphosphate and / or adenosine diphosphate.

[0009] The inorganic material is selected from one or more of boron nitride, clay, or hydroxyapatite.

[0010] When the phosphorus-nitrogen-containing biomolecule-modified inorganic flame retardant is an adenosine-based phosphate-nitrogen flame retardant, the preparation method of the phosphorus-nitrogen-containing biomolecule-modified inorganic flame retardant includes the following steps:

[0011] (1) Disperse the nitrogen-based flame retardant in deionized water and stir it evenly at 80-110℃ to obtain an aqueous solution of nitrogen-based flame retardant with a mass concentration of 7.0-9.5 mg / mL;

[0012] (2) In a molar ratio of adenosine triphosphate: nitrogen-based flame retardant = 1:3, adenosine diphosphate: nitrogen-based flame retardant = 1:2, an aqueous solution of adenosine phosphate with a mass concentration of 9.3-13.0 mg / mL is mixed with an aqueous solution of nitrogen-based flame retardant at a rate of 200-400 r / min, and stirred for 1-2 h to obtain an aqueous suspension of adenosine triphosphate-nitrogen-based flame retardant;

[0013] (3) The adenosine triphosphate-nitrogen flame retardant suspension aqueous solution is separated into solid and liquid components. The product after solid-liquid separation is dried to obtain adenosine triphosphate-nitrogen flame retardant powder.

[0014] In step (1), the stirring time for uniform mixing is preferably 1-2 hours.

[0015] In step (3), the drying temperature is 60-80℃.

[0016] When the phosphorus-nitrogen biomolecule-modified inorganic flame retardant is a mixture of inorganic material, adenosine triphosphate, and nitrogen-based flame retardant, the preparation method of the phosphorus-nitrogen biomolecule-modified inorganic flame retardant includes the following steps:

[0017] (a) By mass ratio, adenosine phosphate-nitrogen flame retardant: inorganic material = (5-20): (20-25), by molar ratio, adenosine triphosphate: nitrogen flame retardant = 1:3, adenosine diphosphate: nitrogen flame retardant = 1:2, weigh the materials;

[0018] (b) Disperse the inorganic material and nitrogen-based flame retardant in an aqueous solution and ball mill for 8-12 hours at a ball mill speed of 400-600 r / min to obtain a mixture; wherein, according to the solid-liquid ratio, the total mass of inorganic material and nitrogen-based flame retardant: water = 20-30 mg: 1 mL;

[0019] (c) Mix an aqueous solution of adenosine phosphate with a mass concentration of 9.3-13 mg / mL with the mixture, and stir at 80-110℃ for 8-12 h to obtain a suspension;

[0020] (d) The suspension is separated into solid and liquid phases, and the solid product is dried to obtain an inorganic material-adenosine phosphate-nitrogen flame retardant mixture.

[0021] In step (b), the grinding balls are stainless steel balls or zirconia balls, preferably zirconia balls.

[0022] In step (b), the total mass ratio of spheres to inorganic materials and nitrogen-based flame retardants is 10-20:1, preferably 13:1.

[0023] In step (d), the solid-liquid separation is preferably performed by centrifugation, and the drying temperature for drying the solid product is 60-80℃.

[0024] The present invention proposes a flame-retardant rubber, which uses the above-mentioned phosphorus and nitrogen-containing biomolecule-modified inorganic flame retardant as a flame-retardant component. The raw materials included by mass are: 100 parts of dry rubber in rubber latex and 5-50 parts of phosphorus and nitrogen-containing biomolecule-modified inorganic flame retardant.

[0025] Preferably, the phosphorus-nitrogen biomolecular modified inorganic material flame retardant is a mixture of inorganic material-adenosine phosphate-nitrogen flame retardant.

[0026] The rubber latex is preferably a latex-type rubber, preferably one of natural rubber latex, polybutadiene rubber latex, styrene-butadiene rubber latex, and isoprene rubber latex, and more preferably natural rubber latex.

[0027] The flame-retardant rubber described herein has no flame retardancy rating.

[0028] The preparation method of the above flame-retardant rubber includes the following steps:

[0029] Step 1: Weigh the raw materials according to the raw material ratio of flame retardant rubber;

[0030] Among them, (1) matrix: 100 parts of dry rubber in rubber latex;

[0031] (2) Phosphorus-nitrogen biomolecule modified inorganic material flame retardant: 5-50 parts;

[0032] Step 2: Add the phosphorus and nitrogen-containing biomolecule-modified inorganic flame retardant to the aqueous solution and ultrasonically disperse for 2-3 hours to obtain the flame retardant aqueous solution;

[0033] Step 3: Mix the rubber latex and flame retardant aqueous solution, stir for 2-3 hours at a stirring rate of 30-200 r / min to obtain a mixture;

[0034] Step 4: Add flocculant to the mixture for flocculation to obtain rubber pellets, dry them, and the dried rubber pellets are flame-retardant rubber;

[0035] The flocculant is preferably a calcium chloride solution with a mass concentration of 0.5-2%, which is prepared by mixing calcium chloride and water and stirring for 15 minutes.

[0036] In step 4, the amount of flocculant added is 2.5-3.5% of the dry rubber mass in the rubber latex.

[0037] Flame-retardant rubber is plasticized and vulcanized to obtain vulcanized flame-retardant rubber; based on steps 1-4, the following steps are included:

[0038] Step 5: Dry the rubber pellets and then masticate them at a temperature of 30-35℃ for 15-30 minutes. Add vulcanizing agent and accelerator during mastication to obtain the masticated product. By mass, the rubber latex contains 100 parts dry rubber, 2-4 parts vulcanizing agent, and 1-2.5 parts accelerator.

[0039] Step 6: Vulcanize the plasticized product under a flat vulcanizing machine and allow it to cool naturally to obtain the vulcanized flame-retardant rubber.

[0040] In step 6, the vulcanization time and temperature are determined according to the vulcanization curve, and are preferably maintained at 143-150℃ for 15-30 minutes.

[0041] In step 1, the mass fraction of dry rubber in the rubber latex is 58-61%.

[0042] In step 5, the vulcanizing agent is preferably sulfur.

[0043] In step 5, the accelerator is preferably zinc diethyldithiocarbamate (ZDC).

[0044] The vulcanized flame-retardant rubber, prepared using a phosphorus-nitrogen biomolecule-modified inorganic flame retardant as the flame retardant and the above method, has a limiting oxygen index (LOI) of 21.3-31.3% and a vertical burning rating of V0-V2. With the addition of the inorganic adenosine phosphate-nitrogen flame retardant, the tensile strength increases by 27.4-46.1%. The thermal stability at 5% thermal weight loss corresponds to a 25°C increase in temperature compared to the temperature without the flame retardant, a 6-second delay in ignition time, and a 24.9% increase in residual char.

[0045] The beneficial effects of this invention are:

[0046] This invention designs a phosphorus-nitrogen-containing biomolecular modification of inorganic flame retardants, enabling the prepared flame-retardant rubber to produce non-flammable gases upon thermal decomposition. These non-flammable gases have cooling, heat-absorbing, and oxygen-diluting effects on combustible materials, thus achieving flame retardancy. Furthermore, the adenosine phosphate used is a biomolecular material that is low-cost, widely available, environmentally friendly, and renewable. Through the combination of adenosine phosphate and nitrogen-based flame retardants, the phosphorus source decomposes upon heating, releasing phosphorus-containing compounds that cover the surface, forming a protective layer. The phosphate compounds also have a dehydrating effect, causing the polymer to dehydrate and carbonize, forming a dense carbon layer. The synergistic effect of phosphorus and nitrogen elements, the thermal decomposition of nitrogen-containing compounds to produce non-flammable gases, and the expansion of the carbon layer under acidic conditions, can better isolate heat transfer and improve flame retardancy. By adding inorganic materials, which have good thermal stability and are compatible with natural rubber, the mechanical properties are maintained while further improving flame retardancy. Inorganic materials can form a strong barrier layer on the surface, slowing down the heat transfer process, and the type of flame retardant added can be adjusted according to the application requirements of the rubber. Attached Figure Description

[0047] Figure 1 The operation flow is shown in Embodiments 1-3 of the present invention.

[0048] Figure 2 The operation flow is shown in Embodiments 4-9 of the present invention.

[0049] Figure 3 The following is the operation process of comparative examples 10-12 of the present invention.

[0050] Figure 4 The following is the operation process of Comparative Example 1 of the present invention.

[0051] Figure 5 The following is the operation process of comparative examples 2-4 of the present invention. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the embodiments.

[0053] In the following examples, the adenosine phosphate and nitrogen-based flame retardants used were all purchased commercially.

[0054] In the following examples, the clay, boron nitride, and hydroxyapatite used were purchased commercially.

[0055] The sulfur used in the following examples was purchased from the market.

[0056] In the following embodiments, the ZDC used was purchased from the market.

[0057] In the following examples, the natural latex used was purchased from Hainan Natural Rubber Co., Ltd.

[0058] In the following embodiments, unless otherwise specified, the test methods used are all based on industry or national standards.

[0059] In the following examples, the thermal stability test conditions were as follows: using a thermal analyzer, under nitrogen protection, the temperature was increased from room temperature to 600°C at a heating rate of 10°C / min.

[0060] The following embodiments illustrate a method for preparing adenosine-based phosphate-nitrogen flame retardants, comprising the following steps:

[0061] (1) Disperse the nitrogen-based flame retardant in deionized water and stir at 80-110℃ for 1-2 hours to obtain an aqueous solution of nitrogen-based flame retardant with a mass concentration of 7.0-9.5 mg / mL;

[0062] (2) In a molar ratio of adenosine triphosphate: nitrogen flame retardant = 1:3, adenosine diphosphate: nitrogen flame retardant = 1:2, an aqueous solution of adenosine triphosphate with a mass concentration of 9.3-13.0 mg / mL was mixed with an aqueous solution of nitrogen flame retardant at a rate of 200-400 r / min, and stirred for 1-2 h to obtain an aqueous suspension of adenosine phosphate-nitrogen flame retardant;

[0063] (3) Centrifuge the aqueous solution of adenosine-based phosphoric acid-nitrogen flame retardant, and dry the solid product obtained by centrifugation at 60-80℃ to obtain adenosine-based phosphoric acid-nitrogen flame retardant powder.

[0064] In the following embodiments, the inorganic material-adenosine phosphate-nitrogen-based flame retardant mixture is prepared by the following method, specifically including the following steps:

[0065] (a) By mass ratio, adenosine phosphate-nitrogen flame retardant: inorganic material = (5-20): (20-25), by molar ratio, adenosine triphosphate: nitrogen flame retardant = 1:3, adenosine diphosphate: nitrogen flame retardant = 1:2, weigh the materials;

[0066] (b) Disperse the inorganic material and nitrogen-based flame retardant in an aqueous solution and ball mill for 8-12 hours at a ball mill speed of 400-600 r / min to obtain a mixture; wherein, according to the solid-liquid ratio, the total mass of inorganic material and nitrogen-based flame retardant: water = 20-30 mg: 1 mL;

[0067] (c) Mix an aqueous solution of adenosine triphosphate with a mass concentration of 9.3-13 mg / mL with the mixture, and stir at 80-110℃ for 8-12 h to obtain a suspension;

[0068] (d) Centrifuge the suspension and dry the solid product obtained by centrifugation at 60-80℃ to obtain an inorganic material-adenosine triphosphate-nitrogen flame retardant mixture.

[0069] Example 1

[0070] A flame-retardant rubber, wherein the matrix is ​​natural rubber latex; the preparation process of the flame-retardant rubber is as follows. Figure 1 This includes the following steps:

[0071] Step 1: The inorganic material and nitrogen-based flame retardant are ball-milled in an aqueous solution for 8 hours at a speed of 400-600 r / min to obtain a mixture; in this embodiment, boron nitride is used as the inorganic material and melamine is used as the nitrogen-based flame retardant.

[0072] Step 2: Mix the aqueous solution of adenosine phosphate with the mixture from Step 1, and stir magnetically at 80°C for 8 hours. In this embodiment, the adenosine phosphate is adenosine triphosphate, and the total amount of adenosine triphosphate-nitrogen flame retardant is 15 parts. The molar ratio of adenosine triphosphate to nitrogen flame retardant is 1:3, and the amount of hydroxyapatite is 20 parts.

[0073] Step 3: Dry the product obtained in Step 2 at 60°C to obtain an inorganic material-adenosine phosphate-nitrogen flame retardant mixture powder;

[0074] Step 4: Dissolve the inorganic material-adenosine phosphate-nitrogen flame retardant mixture powder from Step 3 in water and ultrasonically disperse for 1-2 hours to obtain an aqueous flame retardant solution;

[0075] Step 5: Mix 100 parts of natural rubber latex with the flame retardant obtained in Step 4, and stir for 2-3 hours to obtain a mixture;

[0076] Step 6: Add a 1% (w / w) calcium chloride solution to the mixture from Step 5 for flocculation to obtain rubber pellets; in this embodiment, calcium chloride accounts for 3% of the dry rubber mass.

[0077] Step 7: Transfer the rubber pellets to a vacuum oven (100℃), vacuum degree -0.09MPa~-0.10MPa, until dry and free of moisture;

[0078] Step 8: Plasticize the dried rubber on a two-roll mill at 35°C for 20 minutes, while adding vulcanizing agent and accelerator; wherein, the vulcanizing agent is 2.5 parts of sulfur and the accelerator is 1.5 parts of ZDC.

[0079] Step 9: Hold the plasticized product obtained in Step 8 at 143°C for 15 minutes in a flat vulcanizing machine and allow it to cool naturally to obtain the vulcanized flame-retardant rubber.

[0080] Example 2

[0081] A flame-retardant rubber is prepared in the same way as in Example 1, except that the inorganic material used in this example is clay.

[0082] Example 3

[0083] A flame-retardant rubber is prepared in the same way as in Example 1, except that the inorganic material used in this example is hydroxyapatite.

[0084] Example 4

[0085] A flame-retardant rubber, wherein the matrix is ​​natural rubber latex; the preparation process of the flame-retardant rubber is as follows. Figure 2 This includes the following steps:

[0086] Step 1: Disperse the nitrogen-based flame retardant in water using ultrasonication for 1-2 hours. In this example, the adenosine phosphate is adenosine triphosphate, and the total amount of adenosine triphosphate-melamine nitrogen-based flame retardant is 5 parts, with a molar ratio of adenosine triphosphate to nitrogen-based flame retardant of 1:3.

[0087] Step 2: Mix adenosine phosphate with nitrogen-based flame retardant solution and stir magnetically at 80°C for 8 hours;

[0088] Step 3: Dry the product obtained in Step 2 at 60°C to obtain a mixture powder of adenosine phosphate-nitrogen flame retardant;

[0089] Step 4: Dissolve the adenosine-based phosphate-nitrogen flame retardant mixture powder from Step 3 in water and ultrasonically disperse for 1-2 hours to obtain an aqueous flame retardant solution;

[0090] Step 5: Mix 100 parts of natural rubber latex with the flame retardant aqueous solution obtained in Step 4, and stir for 2-3 hours to obtain a mixture;

[0091] Step 6: Add a 1% (w / w) calcium chloride solution to the mixture from Step 5 for flocculation to obtain rubber pellets; in this embodiment, calcium chloride accounts for 3% of the dry rubber mass.

[0092] Step 7: Transfer the rubber pellets to a vacuum oven (100℃), vacuum degree -0.09MPa~-0.10MPa, until dry and free of moisture;

[0093] Step 8: Plasticize the dried rubber on a two-roll mill at 35°C for 20 minutes, while adding vulcanizing agent and accelerator; wherein, the vulcanizing agent is 2.5 parts of sulfur and the accelerator is 1.5 parts of ZDC.

[0094] Step 9: Hold the plasticized product obtained in Step 8 at 143°C for 15 minutes in a flat vulcanizing machine and allow it to cool naturally to obtain flame-retardant rubber.

[0095] Example 5

[0096] A flame-retardant rubber is prepared in the same way as in Example 4, except that the adenosine phosphate-nitrogen flame retardant used in this example is 10 parts.

[0097] Example 6

[0098] A flame-retardant rubber is prepared in the same way as in Example 4, except that the adenosine phosphate-nitrogen flame retardant used in this example is 15 parts.

[0099] Example 7

[0100] A flame-retardant rubber is prepared in the same way as in Example 4, except that the adenosine phosphate-nitrogen flame retardant used in this example is 20 parts.

[0101] Example 8

[0102] A flame-retardant rubber is prepared in the same way as in Example 6, except that the nitrogen-based flame retardant used in this example is dicyandiamine.

[0103] Example 9

[0104] A flame-retardant rubber is prepared in the same way as in Example 6, except that the adenosine phosphate used in this example is adenosine diphosphate, and the molar ratio of adenosine diphosphate to nitrogen-based flame retardant is 1:2.

[0105] Example 10

[0106] A flame-retardant rubber, wherein the matrix is ​​natural rubber latex; the preparation process of the flame-retardant rubber is as follows. Figure 3 This includes the following steps:

[0107] Step 1: Disperse boron nitride and nitrogen-based flame retardant in an aqueous solution and ultrasonically disperse for 1-2 hours; then add adenosine phosphate and magnetically stir at 80°C for 8 hours. In this example, the adenosine phosphate used is adenosine triphosphate, and the nitrogen-based flame retardant is melamine; the total amount of adenosine phosphate-nitrogen-based flame retardant is 15 parts, with a molar ratio of 1:3, and 20 parts of boron nitride.

[0108] Step 2: Mix the latex containing 100 parts of rubber with the solution from Step 1 and stir for 2-3 hours;

[0109] Step 3: Add a 1% calcium chloride solution to the solution from Step 2 for flocculation; in this example, calcium chloride accounts for 3% of the dry gel mass.

[0110] Step 4: Pelletize the mixture and transfer it to a vacuum oven (100℃) with a vacuum degree of -0.09MPa to -0.10MPa until it is dry and free of moisture.

[0111] Step 5: Plasticize the dried rubber on a two-roll mill at 35°C for 20 minutes, while adding vulcanizing agent.

[0112] Step 6: The vulcanizing agents used in Step 5 are 2.5 parts sulfur and 1.5 parts ZDC.

[0113] Step 7: Hold the product obtained in Step 5 at 143°C for 15 minutes in a flat vulcanizing machine, and then allow it to cool naturally to obtain the composite product.

[0114] Example 11

[0115] A flame-retardant rubber is prepared in the same way as in Example 10, except that the inorganic material used in this example is clay.

[0116] Example 12

[0117] A flame-retardant rubber is prepared in the same way as in Example 10, except that the inorganic material used in this example is hydroxyapatite.

[0118] Comparative Example 1

[0119] A method for preparing rubber, the process of which is as follows: Figure 4 This includes the following steps:

[0120] Step 1: Add a 1% calcium chloride solution to a mixture containing 100 parts of natural rubber latex for flocculation;

[0121] Step 2: Transfer the natural rubber to a vacuum oven (100℃), with a vacuum degree of -0.09MPa to -0.10MPa, until it is dry and free of moisture;

[0122] Step 3: Plasticize the dried rubber on a two-roll mill at 35°C for 20 minutes, while adding vulcanizing agent and accelerator; the vulcanizing agent is 2.5 parts sulfur and the accelerator is 1.5 parts ZDC.

[0123] Step 4: Hold the plasticized product obtained in Step 3 at 143°C for 15 minutes in a flat vulcanizing machine, and then let it cool naturally to obtain rubber.

[0124] Comparative Example 2

[0125] A method for preparing rubber, the process of which is as follows: Figure 5 This includes the following steps:

[0126] Step 1: Ball mill 25 parts of boron nitride in an aqueous solution for 8 hours;

[0127] Step 2: Dry the product obtained in Step 1;

[0128] Step 3: Disperse boron nitride powder in an aqueous solution using ultrasound for 1-2 hours;

[0129] Step 4: Mix the latex containing 100 parts of rubber with the solution from Step 3 and stir for 2-3 hours;

[0130] Step 5: Add a 1% calcium chloride solution to the solution from Step 2 for flocculation;

[0131] Step 6: Pelletize the mixture and transfer it to a vacuum oven (100℃) with a vacuum degree of -0.09MPa to -0.10MPa until it is dry and free of moisture.

[0132] Step 7: Plasticize the dried rubber on a two-roll mill at 35°C for 20 minutes, while adding vulcanizing agent.

[0133] Step 8: The vulcanizing agents used in Step 5 are 2.5 parts sulfur and 1.5 parts ZDC;

[0134] Step 9: Hold the product obtained in Step 5 at 143°C for 15 minutes in a flat vulcanizing machine, and then allow it to cool naturally to obtain the composite product.

[0135] Comparative Example 3

[0136] A flame-retardant rubber is prepared in the same way as Comparative Example 2, except that the inorganic material used in this embodiment is clay.

[0137] Comparative Example 4

[0138] A flame-retardant rubber is prepared in the same way as Comparative Example 2, except that the inorganic material used in this embodiment is hydroxyapatite.

[0139] Comparative Example 5

[0140] The preparation method of inorganic material-adenosine triphosphate-nitrogen flame retardant mixture is as follows: adenosine triphosphate-nitrogen flame retardant and hydroxyapatite are mixed and ball-milled for 8-12 hours at a ball milling speed of 400-600 r / min to obtain flame retardant mixture;

[0141] The flame-retardant mixture was filtered, and the solid product contained no adenosine triphosphate.

[0142] Table 1. Number of filler parts

[0143]

[0144] Table 2 Mechanical Performance Test Data

[0145]

[0146]

[0147] As shown in Table 2, the flame-retardant rubber with only adenosine-based phosphate-nitrogen flame retardant mixture showed a 4.4-19.4% decrease in tensile strength and a 5.1%-22.1% decrease in elongation at break compared to flame-retardant natural rubber without flame retardant, while the hardness remained almost unchanged. Conversely, the flame-retardant natural rubber with inorganic material-adenosine-based phosphate-nitrogen flame retardant mixture showed a 27.4%-46.1% increase in tensile strength, a 25.3%-32.9% decrease in elongation at break, and a 16.2-24.3% increase in hardness compared to the natural rubber without flame retardant.

[0148] Table 3 Mechanical property test data

[0149]

[0150] Table 4 Thermal Performance Test Data

[0151]

[0152]

[0153] Table 4 shows that the flame-retardant rubber with added phosphorus-nitrogen-containing biomolecularly modified inorganic flame retardants exhibits improved thermal degradation performance compared to the flame-retardant rubber without such additives. 5％ The maximum temperature increase is 25°C, T max The maximum temperature delay is 38°C, and the residual carbon content at 600°C is increased by a maximum of 24.9%.

[0154] The flame retardant properties of the products obtained in the above embodiments and comparative examples were tested, and their limiting oxygen index (LOI) and vertical burning registration test data are shown in Table 5:

[0155] Table 5 Flame retardant properties

[0156]

[0157] According to the flame retardant performance test results in Table 5, it can be seen that the flame-retardant rubber with the addition of the inorganic material-adenosine phosphate-nitrogen flame retardant mixture has a higher limiting oxygen index than the flame-retardant rubber with the addition of the inorganic material-adenosine phosphate-nitrogen flame retardant mixture. This indicates that the flame retardant properties of the inorganic material-adenosine phosphate-nitrogen flame retardant mixture are more effective. The limiting oxygen index of the flame-retardant rubber with the addition of the adenosine phosphate-nitrogen flame retardant mixture is increased by 1.8-5.6%, while the limiting oxygen index of the flame-retardant rubber with the addition of the inorganic material-adenosine phosphate-nitrogen flame retardant mixture is increased by 8.6-11.8%.

[0158] Based on its vertical flammability rating (UL-94), it indicates that using an inorganic material-adenosine phosphate-nitrogen-based flame retardant mixture as a flame retardant can achieve a vertical flammability rating of V-0. Considering the overall flame retardant effect, the inorganic material-adenosine phosphate-nitrogen-based flame retardant mixture as a flame retardant has a better flame retardant effect.

[0159] Table 6. Test data from the cone calorimeter

[0160]

[0161] According to Table 6, flame-retardant rubbers with added phosphorus and nitrogen-containing biomolecular modified inorganic flame retardants can all have their ignition time (TTI) extended. Among them, flame-retardant rubbers with added inorganic material-adenosine phosphate-nitrogen flame retardant mixtures have a greater effect, with a maximum TTI extension time of 6 seconds. The extension of TTI also indicates that adding inorganic material-adenosine phosphate-nitrogen flame retardant mixtures can reduce the fire hazard of natural rubber.

[0162] Based on the peak heat release rate (PHRR), it is shown that the addition of phosphorus and nitrogen-containing biomolecular modified inorganic flame retardants can reduce their heat release rate, and the reduction is 6.4%-28.8% compared with no flame retardant added. Furthermore, the flame retardant rubber with the addition of inorganic material-adenosine phosphate-nitrogen flame retardant mixture has a more effective reduction in heat release rate, with a maximum reduction of 28.8%.

[0163] According to the total heat release (THR), flame-retardant rubber with added phosphorus and nitrogen-containing biomolecular modified inorganic flame retardants can effectively reduce the total heat release of flame-retardant rubber. The effect of adding a mixture of inorganic materials-adenosine phosphate-nitrogen flame retardants is even better, with a 21.2% reduction compared to flame-retardant rubber without added flame retardants.

[0164] Based on the effective heat of combustion (EHC), it is shown that the flame-retardant rubber with added phosphorus and nitrogen-containing biomolecular modified inorganic flame retardants releases less heat during combustion. Compared with flame-retardant rubber without added flame retardants, flame-retardant rubber with added inorganic material-adenosine phosphate-nitrogen flame retardant mixture is more effective in reducing the degree of combustion, with a maximum reduction of 24.8%.

[0165] According to the mass loss rate (MLR), flame-retardant rubber with added phosphorus and nitrogen-containing biomolecular modified inorganic flame retardants can effectively reduce the thermal decomposition, volatilization and combustion of natural rubber under a certain fire intensity. The flame-retardant rubber with added inorganic material-adenosine phosphate-nitrogen flame retardant mixture has the largest reduction of 16.1% compared with others.

Claims

1. A flame-retardant rubber, characterized in that, The flame-retardant rubber uses a phosphorus-nitrogen-containing biomolecule-modified inorganic material flame retardant as the flame-retardant component. The raw materials included in the flame-retardant rubber are as follows by mass: 100 parts of dry rubber in rubber latex and 5-50 parts of the flame retardant. The flame retardant is a mixture of inorganic materials, adenosine phosphate, and nitrogen-based flame retardants; by mass ratio, adenosine phosphate-nitrogen-based flame retardant: inorganic materials = (5-20): (20-25); by molar ratio, adenosine phosphate: nitrogen-based flame retardant = 1:3; The adenosine phosphate is selected from adenosine triphosphate, the nitrogen-based flame retardant is selected from melamine, and the inorganic material is selected from one or more of clay or hydroxyapatite. The method for preparing the flame retardant includes the following: (a) Disperse inorganic materials and nitrogen-based flame retardants in an aqueous solution and ball mill for 8-12 hours at a ball mill speed of 400-600 r / min to obtain a mixture; (b) Mix an aqueous solution of adenosine phosphate with a mass concentration of 9.3-13 mg / mL with the mixture, and stir at 80-110℃ for 8-12 h to obtain a suspension; (c) The suspension is separated into solid and liquid phases, and the solid product is dried to obtain the flame retardant, namely, the inorganic material-adenosine phosphate-nitrogen flame retardant mixture.

2. The method for preparing flame-retardant rubber according to claim 1, characterized in that, Includes the following: Step 1: Weigh the raw materials according to the raw material ratio of flame retardant rubber; The matrix consists of 100 parts of dry rubber in rubber latex; and 5-50 parts of phosphorus and nitrogen-containing biomolecule-modified inorganic flame retardant. Step 2: Add the phosphorus and nitrogen-containing biomolecule-modified inorganic flame retardant to the aqueous solution and ultrasonically disperse for 2-3 hours to obtain the flame retardant aqueous solution; Step 3: Mix the rubber latex and flame retardant aqueous solution, stir for 2-3 hours at a stirring rate of 30-200 r / min to obtain a mixture; Step 4: Add flocculant to the mixture for flocculation to obtain rubber pellets, dry them, and the dried rubber pellets are flame-retardant rubber.

3. The method for preparing flame-retardant rubber according to claim 2, characterized in that, The flocculant is a calcium chloride solution with a mass concentration of 0.5-2%, and the amount of flocculant added is 2.5-3.5% of the dry rubber mass in the rubber latex.

4. The method for preparing flame-retardant rubber according to claim 2, characterized in that, Flame-retardant rubber is plasticized and vulcanized to obtain vulcanized flame-retardant rubber; based on steps 1-4, the following steps are included: Step 5: Dry the rubber pellets and then masticate them at a temperature of 30-35℃ for 15-30 minutes. Add vulcanizing agent and accelerator during mastication to obtain the masticated product. By mass, the rubber latex contains 100 parts dry rubber, 2-4 parts vulcanizing agent, and 1-2.5 parts accelerator. Step 6: Vulcanize the plasticized product under a flat vulcanizing machine and allow it to cool naturally to obtain the vulcanized flame-retardant rubber.

5. A vulcanized flame-retardant rubber, characterized in that, It was prepared by the method described in claim 4.

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