Carbon-modified phosphorus-free plastic for improving flame retardancy and preparation method thereof

Abstract

The invention discloses a carbon-modified phosphorus-free plastic for improving flame retardancy. The carbon-modified phosphorus-free plastic comprises the following components by weight: 60-80% of alumina clinker, 5-10% of composite fine powder, 4-6% of high-alumina cement, 5-7% of a phosphorus-free flame retardant, 2-3% of a dispersant, and the balance of water. The phosphorus-free flame retardant comprises the following raw materials by weight: 15-17 parts of boric acid, 3-5 parts of epoxy resin, 3-5 parts of melamine, 1-1.5 parts of a carbonization accelerator A, and 0.8-1 part of a carbonization accelerator B. The preparation method comprises the following steps: S1, premixing; S2, mixing; and S3, compression molding. The carbon-modified phosphorus-free plastic of the invention, by adding a phosphorus-free flame retardant, can ensure that the plastic has high flame retardancy while avoiding the problem of greatly shortening the storage period of the plastic due to chemical reaction between phosphorus and components in the plastic.

Description

Technical Field

[0001] The invention relates to the technical field of plastic preparation, in particular to a carbon-modified phosphorus-free plastic for improving flame retardancy and a preparation method thereof. Background Art

[0002] Plastic is a paste-like material made primarily of refractory aggregate, with an appropriate clay or chemical binder, a small amount of admixtures, and water. It maintains excellent plasticity within a specified storage period. Currently, the most common type of plastic is thermosetting plastic, which hardens during baking. Its composition is: 55-70% aggregate (clay clinker or high-alumina clinker); 25-35% powder; and 5-15% binder (soft clay). It has a shelf life of six months.

[0003] Adding phosphorus-containing flame retardants to plastics can address the flammability issues of most plastic materials. Currently, the most widely used flame retardants on the market include inorganic, halogen, phosphorus, and nitrogen-phosphorus flame retardants. Halogen-free, low-smoke, and low-toxicity environmentally friendly flame retardants are a long-standing goal. Halogen-free flame retardants primarily include phosphorus-based flame retardants and inorganic hydrates. Red phosphorus flame retardants are widely used in plastics, hot-melt adhesives, rubber, coatings, and other products due to their excellent flame retardant efficacy and high flame retardant efficiency. Phosphorus is a highly effective flame retardant, especially for plastics. The effects of phosphorus-containing flame retardants are not simply oxidative, but primarily affect the aggregation phase. When phosphorus and plastic materials burn together, a series of changes occur, forming polymetaphosphoric acid (PMP). PMP forms a thin, viscous film that covers the polymer surface, reducing oxygen contact and inhibiting oxidation. Furthermore, phosphorus-derived phosphoric acid, metaphosphoric acid, and PMP act as dehydrating agents, promoting dehydration and carbonization of the polymer, enhancing flame retardancy.

[0004] However, the iron oxide content in plastic raw materials is high, and phosphoric acid and phosphates easily react chemically with the iron oxide, significantly shortening the plastic's shelf life. Furthermore, phosphorus is a highly detrimental element in steel. Its presence reduces its low-temperature toughness and increases its brittleness. At high temperatures, phosphorus also affects its plasticity. Based on this, the present invention provides a carbon-modified, phosphorus-free plastic with enhanced flame retardancy and a method for its preparation. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a carbon-modified phosphorus-free plastic material for improving flame retardancy and a preparation method thereof.

[0006] The technical solution of the present invention is: a carbon-modified phosphorus-free plastic for improving flame retardancy, comprising the following components by weight: 60-80% alumina clinker, 5-10% composite fine powder, 4-6% high-alumina cement, 5-7% phosphorus-free flame retardant, 2-3% dispersant and the balance water;

[0007] The composite fine powder is composed of 5 to 7 parts of SiO2 fine powder and 3 to 5 parts of active α-Al2O3 fine powder in parts by weight;

[0008] The phosphorus-free flame retardant comprises the following raw materials in parts by weight: 15 to 17 parts of boric acid, 3 to 5 parts of epoxy resin, 3 to 5 parts of melamine, 1 to 1.5 parts of carbonization accelerator A, and 0.8 to 1 parts of carbonization accelerator B; wherein the carbonization accelerator A is o-cresol-formaldehyde resin, and the carbonization accelerator B is a mixture of magnesium hydroxide and aluminum hydroxide in equal weight proportions;

[0009] Description: The above raw materials can ensure that the plastic has high flame retardant properties while avoiding the chemical reaction between phosphorus and iron oxide in the plastic, thereby greatly shortening the storage period of the plastic by adopting a phosphorus-free flame retardant; o-cresol-formaldehyde resin can act on the resin at high temperature to solidify it into charcoal, thereby serving as a carbon source for the flame retardant; the carbonization accelerator B using the above ingredients can effectively burn into a metal compound, which is loaded on a porous carbon material with a high specific surface area and can serve as the main component of the carbon layer to significantly improve the flame retardant efficiency; at the same time, it can also burn to produce a large amount of acidic gas as the acid source of the flame retardant, and magnesium and aluminum form spinel, which can effectively enhance the compressive and flexural strength of the plastic.

[0010] Furthermore, the preparation method of the phosphorus-free flame retardant is:

[0011] 1) taking carbon forming accelerator A and carbon forming accelerator B according to the ratio, spraying 99% anhydrous ethanol at a rate of 30 to 50 mL / min onto the surfaces of carbon forming accelerator A and carbon forming accelerator B, respectively, and then drying at room temperature and grinding carbon forming accelerator A and carbon forming accelerator B into particles with a particle size of 1 to 1.5 mm using a ball mill to obtain granular carbon forming accelerator A and granular carbon forming accelerator B;

[0012] 2) putting epoxy resin into a crucible, sequentially adding granular carbonization accelerator A and 1 / 3 granular carbonization accelerator B into the crucible, heating to 800-820° C., and ultrasonically vibrating for 15-20 minutes to obtain a carbon-based material;

[0013] 3) Boric acid, melamine, and the carbon-based material prepared in step 2) are weighed according to the ratio and placed in a four-necked flask. The four-necked flask is heated to 85-100° C., and the remaining amount of granular carbonization accelerator B is added to the four-necked flask. The temperature is further raised to 350-400° C. and stirred using a magnetic stirrer for 20-30 minutes to obtain a carbonized layer, which is the phosphorus-free flame retardant.

[0014] Description: Grinding the carbonization accelerator first can increase the contact area, thereby improving the preparation efficiency of the phosphorus-free flame retardant; from the experimental data, it can be obtained that selecting a part of the carbonization accelerator A and heating it to 800℃ first can make the curing carbonization rate of the o-cresol resin to the resin reach a higher level, thereby supplementing the carbon source. At the same time, the carbonization accelerator B can be completely decomposed at 800℃, thereby more fully preparing the carbon-based material; and then at 400℃, the carbonization accelerator B decomposes and absorbs the heat on the surface of the burning material, thereby playing a flame retardant role. At the same time, a large amount of water will be released to dilute the oxygen on the surface of the burning material. The active magnesium oxide and aluminum oxide generated by the decomposition will adhere to the surface of the combustible material, further preventing the combustion and improving the flame retardant effect of the phosphorus-free flame retardant.

[0015] Furthermore, the ultrasonic frequency in step 2) is 18 to 20 kHz;

[0016] Note: Ultrasonic mixing can effectively improve the mixing effect. The carbon-based material prepared under the above parameters has a higher carbon content, which is more conducive to the preparation efficiency of the carbonized layer.

[0017] Further, the carbonized layer obtained in step 3) is subjected to a grafting treatment;

[0018] The grafting treatment method comprises: using a plasma treatment apparatus to clean the surface of the carbonized layer for 3 to 5 minutes; weighing the raw materials according to the mass ratio of carbonized layer: azobisisobutyronitrile: nitrogen-containing compound with a mass concentration of 30 to 40 mg / L of 3 to 5: 1 to 3: 0.5 to 1, and dividing the nitrogen-containing compound into n equal parts;

[0019] The carbonized layer and azobisisobutyronitrile are placed in a reaction tube, the temperature of the reaction tube is adjusted to 40-45°C and the pressure is 15-18 MPa, and an infrared lamp is used for irradiation. The mixture is stirred every 12-15 minutes and 1 / n of the nitrogen-containing compound is added until the nitrogen-containing compound is added; wherein 3≤n≤5;

[0020] Description: The introduction of nitrogen-containing compounds can change the chemical properties and structure of the carbonized layer, further improve the hardness and stability of the carbonized layer, and thus improve its flame retardant properties. At the same time, the use of azobisisobutyronitrile as an initiator can not only promote the grafting reaction of the carbonized layer, but also prevent the degradation and aging of the carbonized layer, thereby improving the stability of the carbonized layer; infrared light irradiation can increase the vibration energy of the molecules, thereby accelerating the grafting reaction.

[0021] Furthermore, the cleaned carbonized layer is activated; the activation treatment method is as follows: using 20-30g of concrete as raw material, weighing concrete, Portland cement, and fused magnesia in a mass ratio of 1.5-2:0.8-1:0.5-0.7, fully stirring until molten, and then applying it on the carbonized layer to a thickness of 0.5-1mm and curing for 12-15h;

[0022] Description: Activating the carbonized layer can enhance surface activity, form pores, provide more adsorption sites, and thus enhance the grafting effect and further improve the flame retardant properties; at the same time, it can make the material surface rougher, increase friction, further improve the corrosion resistance and mechanical strength of the material, and extend the service life of the material; fused magnesia has better corrosion resistance and inertness, and silicate cement has better wear resistance, which can play a positive role in promoting the flame retardant effect of the carbonized layer while improving the properties of the plastic.

[0023] Furthermore, the nitrogen-containing compound is a mixture of ethylenediamine or phenylenediamine and nitrogen trioxide or ammonium nitrate in any proportion;

[0024] Description: Amine compounds can react with oxygen-containing groups on the surface of carbon materials to form graft copolymers with flame retardant properties, while nitrogen trioxide and ammonium nitrate can act as oxidants to promote the oxidation reaction of metal particles, thereby forming a carbonized layer with flame retardant properties, further improving the flame retardant properties of the carbonized layer.

[0025] Furthermore, the plasma treatment parameters are: plasma power of 200-220W, plasma frequency of 35-38kHz, argon as the treatment gas, and flow rate of 350-400sccm;

[0026] Note: The plasma treatment under the above settings has better surface cleanliness of the carbonized layer, which helps to improve the subsequent grafting treatment effect.

[0027] The present invention also provides a method for preparing a carbon-modified phosphorus-free plastic for improving flame retardancy, comprising the following steps:

[0028] S1, premix

[0029] At room temperature, alumina clinker was ground and sieved to obtain alumina clinker of three particle sizes: 5-3 mm, 3-1 mm, and ≤1 mm. The mixture obtained by mixing water and high-alumina cement was divided into 6 equal parts. Three parts of the mixture, two parts of the mixture, and one part of the mixture were added to the alumina clinker of the three particle sizes, respectively, for premixing. The premixing time was 5-8 minutes, and base material A, base material B, and base material C were obtained in turn.

[0030] S2, mixed

[0031] Base material A, base material B, base material C and composite fine powder are mixed and crushed into powdery raw materials. 1 / 3 to 1 / 5 of a dispersant is applied to the raw materials every 10 to 12 minutes using a double-roll mixer. 1 / 3 of a phosphorus-free flame retardant is added at the same time. Mixing is continued for 25 to 30 minutes until the phosphorus-free flame retardant is completely applied. The materials are sealed in a bag for 7 to 10 hours to fully react to obtain a mixture.

[0032] S3, compression molding

[0033] The mixture is placed in a mold, and then rammed and formed at a temperature of 170-180° C. and a pressure of 15-20 MPa, and the plastic is obtained by demolding;

[0034] Description: By screening the alumina clinker into three different particle sizes and then mixing it with the mixture, the mixing effect of the base material can be enhanced. Mixing the base material and the composite fine powder into powdered raw materials and adding a dispersant can make the mixing more uniform. Adding the phosphorus-free flame retardant in batches can make the distribution of each component more uniform, further improving the flame retardant properties of the plastic.

[0035] Furthermore, in step S2, the particle size of the powdered raw material is 1 to 1.2 mm;

[0036] Note: If the particle size of the powdered raw material is too small, the mixing effect will be poor, and if the particle size of the powdered raw material is too large, it will lead to uneven mixing and bonding.

[0037] Furthermore, in step S2, the dispersant is composed of polycarboxylic acid with a mass concentration of 9-12%, ammonium stearate, and ethanol with a mass concentration of 4-6% in a mass ratio of 1-1.5:1:0.3-0.5;

[0038] Description: When polycarboxylic acid and ammonium stearate are compounded, the presence of ammonium stearate not only promotes the hydrolysis of the polycarboxylic acid but also increases the repulsive force between the particles, facilitating the bonding of the hydrolyzed nonionics to the surface of the raw material. This not only serves to disperse the polycarboxylic acid but also improves its interfacial compatibility. Polycarboxylic acid has excellent dispersibility and water solubility, while the addition of ethanol promotes the rapid increase in viscosity and consistency of the dispersion by ammonium stearate, further enhancing the mixing efficiency of the mixture and thus improving the flame retardant properties of the plastic.

[0039] The beneficial effects of the present invention are:

[0040] (1) The carbon-modified phosphorus-free plastic of the present invention can, by preparing a phosphorus-free flame retardant, ensure that the plastic has high flame retardant properties while avoiding the problem of greatly shortening the storage period of the plastic due to chemical reaction between phosphorus and iron oxide in the plastic; the addition of carbonization accelerator A and carbonization accelerator B can effectively provide an acid source and a carbon source for the flame retardant, and can also serve as the main component of the carbon layer to significantly improve the flame retardant properties of the plastic.

[0041] (2) The carbon-modified phosphorus-free plastic prepared by the present invention can achieve a higher carbonization rate of the o-cresol-formaldehyde resin by selecting a part of the carbonization accelerator A and heating it to 800°C first, thereby supplementing the carbon source. At the same time, the carbonization accelerator B can be completely decomposed at 800°C, thereby more fully preparing the carbon-based material; and then the carbonization accelerator B decomposes at 400°C to absorb the heat on the surface of the burning material, thereby playing a flame retardant role, effectively improving the flame retardant effect of the phosphorus-free flame retardant.

[0042] (3) The preparation method of the carbon-modified phosphorus-free plastic of the present invention is to enhance the mixing effect of the base material by screening the alumina clinker into different particle sizes and then mixing it with the mixture. The base material and the composite fine powder are then mixed and crushed into a powdered raw material and a dispersant is added to make the mixing more uniform. The phosphorus-free flame retardant is added in batches to make the distribution of each component more uniform, thereby further improving the flame retardant properties of the plastic. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with specific implementation methods to better demonstrate the advantages of the present invention.

[0044] Example 1

[0045] A carbon-modified phosphorus-free plastic for improving flame retardancy comprises the following components, measured by weight: 70% alumina clinker, 8% composite fine powder, 5% high-alumina cement, 6% phosphorus-free flame retardant, 2.5% dispersant, and the balance water; the composite fine powder is composed, by weight, of 6 parts of SiO2 micropowder and 4 parts of active α-Al2O3 micropowder; the phosphorus-free flame retardant comprises, by weight, the following raw materials: 16 parts of boric acid, 4 parts of epoxy resin, 4 parts of melamine, 1.2 parts of carbonization accelerator A, and 0.9 parts of carbonization accelerator B; wherein the carbonization accelerator A is o-cresol-formaldehyde resin, and the carbonization accelerator B is a mixture of magnesium hydroxide and aluminum hydroxide in equal weight proportions;

[0046] The preparation method of the phosphorus-free flame retardant is as follows: 1) taking a carbon-forming accelerator A and a carbon-forming accelerator B according to the ratio, spraying anhydrous ethanol with a mass concentration of 99% on the surface of the carbon-forming accelerator A and the carbon-forming accelerator B at a rate of 40 mL / min, then drying at room temperature and grinding the carbon-forming accelerator A and the carbon-forming accelerator B into particles with a particle size of 1.2 mm using a ball mill to obtain granular carbon-forming accelerator A and granular carbon-forming accelerator B;

[0047] 2) Epoxy resin was placed in a crucible, and granular carbonization accelerator A and 1 / 3 granular carbonization accelerator B were added to the crucible in sequence, and the crucible was heated to 810° C. and subjected to ultrasonic vibration treatment for 18 minutes to obtain a carbon-based material; the ultrasonic frequency was 20 kHz;

[0048] 3) Boric acid, melamine, and the carbon-based material prepared in step 2) were weighed according to the ratio and placed in a four-necked flask. The four-necked flask was heated to 95° C., and the remaining amount of granular carbonization accelerator B was added to the four-necked flask. The temperature was continued to rise to 375° C. and stirred for 25 minutes using a magnetic stirrer to obtain a carbonized layer, which is the phosphorus-free flame retardant.

[0049] The obtained carbonized layer was subjected to a grafting treatment. The grafting treatment method included: cleaning the surface of the carbonized layer using a plasma treatment apparatus for 4 minutes; weighing the raw materials according to a mass ratio of 4:2:0.7 of carbonized layer: azobisisobutyronitrile: nitrogen-containing compound with a mass concentration of 35 mg / L, and dividing the nitrogen-containing compound into n equal parts; plasma treatment parameters were: plasma power of 210 W, plasma frequency of 36 kHz, and argon gas with a flow rate of 375 sccm.

[0050] The carbonized layer and azobisisobutyronitrile were placed in a reaction tube, and the temperature of the reaction tube was adjusted to 42°C and the pressure was 17 MPa. At the same time, an infrared lamp was used for irradiation. The mixture was stirred every 13 minutes and 1 / n of a nitrogen-containing compound was added until the nitrogen-containing compound was added. Wherein, n=4; the nitrogen-containing compound was a mixture of phenylenediamine and dinitrogen trioxide in a ratio of 1:1.

[0051] The method for preparing the carbon-modified phosphorus-free plastic for improving flame retardancy comprises the following steps:

[0052] S1, premix

[0053] At room temperature, bauxite clinker was ground and sieved to obtain bauxite clinker of three particle sizes: 5-3 mm, 3-1 mm, and ≤1 mm. The mixture obtained by mixing water and high-alumina cement was divided into 6 equal parts. Three parts of the mixture, two parts of the mixture, and one part of the mixture were added to the bauxite clinker of the three particle sizes, respectively, for premixing. The premixing time was 7 minutes, and base material A, base material B, and base material C were obtained in turn.

[0054] S2, mixed

[0055] Base material A, base material B, base material C and composite fine powder are mixed and crushed into a powdered raw material with a particle size of 1.1 mm. 1 / 3 of a dispersant is applied to the above raw materials every 11 minutes of mixing using a double-roll mixer. 1 / 3 of a phosphorus-free flame retardant is added at the same time. Mixing is continued for 28 minutes until the phosphorus-free flame retardant is completely applied. The material is sealed in a bag for 8 hours and fully reacted to obtain a mixture; the dispersant is composed of 10% polycarboxylic acid, ammonium stearate, and 5% ethanol in a mass ratio of 1.2:1:0.4;

[0056] S3, compression molding

[0057] The above mixture is placed in a mold, and then rammed into shape at a temperature of 175°C and a pressure of 18 MPa, and the plastic is obtained by demolding.

[0058] Example 2

[0059] Different from Example 1, a carbon-modified phosphorus-free plastic for improving flame retardant properties includes the following components by weight percentage: 60% alumina clinker, 5% composite fine powder, 4% high alumina cement, 5% phosphorus-free flame retardant, 2% dispersant and the balance water.

[0060] Example 3

[0061] Different from Example 1, a carbon-modified phosphorus-free plastic for improving flame retardant properties includes the following components by weight percentage: 80% alumina clinker, 10% composite fine powder, 6% high alumina cement, 7% phosphorus-free flame retardant, 3% dispersant and the balance water.

[0062] Example 4

[0063] The difference from Example 1 is that the composite fine powder is composed of 5 parts of SiO2 fine powder and 3 parts of active α-Al2O3 fine powder in parts by weight.

[0064] Example 5

[0065] The difference from Example 1 is that the composite fine powder is composed of 7 parts of SiO2 fine powder and 5 parts of active α-Al2O3 fine powder in parts by weight.

[0066] Example 6

[0067] Different from Example 1, the phosphorus-free flame retardant includes the following raw materials in parts by weight: 15 parts of boric acid, 3 parts of epoxy resin, 3 parts of melamine, 1 part of carbonization accelerator A and 0.8 part of carbonization accelerator B.

[0068] Example 7

[0069] Different from Example 1, the phosphorus-free flame retardant includes the following raw materials in parts by weight: 17 parts of boric acid, 5 parts of epoxy resin, 5 parts of melamine, 1.5 parts of carbonization accelerator A and 1 part of carbonization accelerator B.

[0070] Example 8

[0071] The difference from Example 1 is that in step 1), anhydrous ethanol with a mass concentration of 99% is sprayed onto the surfaces of carbon-forming accelerator A and carbon-forming accelerator B at a rate of 30 mL / min, and the particles are ground into particles with a particle size of 1 mm.

[0072] Example 9

[0073] The difference from Example 1 is that in step 1), anhydrous ethanol with a mass concentration of 99% is sprayed on the surfaces of carbon-forming accelerator A and carbon-forming accelerator B at a rate of 50 mL / min, and the particles are ground into particles with a particle size of 1.5 mm.

[0074] Example 10

[0075] The difference from Example 1 is that in step 2), the carbon-based material is obtained after heating to 800° C. and ultrasonic vibration treatment for 15 minutes.

[0076] Example 11

[0077] The difference from Example 1 is that in step 2), the carbon-based material is obtained after heating to 820° C. and ultrasonic vibration treatment for 20 minutes.

[0078] Example 12

[0079] The difference from Example 1 is that in step 3), the four-necked flask is heated to 85° C., the remaining amount of granular carbon-forming promoter B is added to the four-necked flask, the temperature is continued to rise to 350° C., and the mixture is stirred for 20 minutes using a magnetic stirrer.

[0080] Example 13

[0081] Different from Example 1, in step 3), the four-necked flask is heated to 100° C., the remaining amount of granular carbon-forming promoter B is added to the four-necked flask, the temperature is continued to rise to 400° C., and the mixture is stirred for 30 minutes using a magnetic stirrer.

[0082] Example 14

[0083] Different from Example 1, the grafting treatment method is as follows: the surface of the carbonized layer is cleaned for 3 minutes using a plasma treatment apparatus; the raw materials are weighed according to a mass ratio of 3:1:0.5 of carbonized layer: azobisisobutyronitrile: nitrogen-containing compound with a mass concentration of 30 mg / L, and the nitrogen-containing compound is divided into n equal parts; wherein n=3;

[0084] The temperature of the reaction tube was adjusted to 40° C. and the pressure was adjusted to 15 MPa. At the same time, infrared light was used for irradiation. The mixture was stirred every 12 minutes and 1 / n of the nitrogen-containing compound was added until all the nitrogen-containing compound was added.

[0085] Example 15

[0086] Different from Example 1, the grafting treatment method is as follows: the surface of the carbonized layer is cleaned for 5 minutes using a plasma treatment apparatus; the raw materials are weighed according to a mass ratio of 5:3:1 of carbonized layer: azobisisobutyronitrile: nitrogen-containing compound with a mass concentration of 40 mg / L, and the nitrogen-containing compound is divided into n equal parts; wherein n=5;

[0087] The temperature of the reaction tube was adjusted to 45° C. and the pressure was adjusted to 18 MPa. At the same time, infrared light was used for irradiation. The mixture was stirred every 15 minutes and 1 / n of the nitrogen-containing compound was added until all the nitrogen-containing compound was added.

[0088] Example 16

[0089] Different from Example 1, the plasma processing parameters are: plasma power of 200 W, plasma frequency of 35 kHz, argon as the processing gas, and flow rate of 350 sccm.

[0090] Example 17

[0091] Different from Example 1, the plasma processing parameters are: plasma power of 220 W, plasma frequency of 38 kHz, argon gas with a flow rate of 400 sccm.

[0092] Example 18

[0093] The difference from Example 1 is that the nitrogen-containing compound is a mixture of ethylenediamine and nitrogen trioxide in a ratio of 1:1.

[0094] Example 19

[0095] The difference from Example 1 is that the nitrogen-containing compound is a mixture of phenylenediamine and ammonium nitrate in a ratio of 1:1.

[0096] Example 20

[0097] The difference from Example 1 is that S2, mixed

[0098] The raw material was crushed into a powder with a particle size of 1 mm, 1 / 3 of the dispersant was applied every 10 minutes of mixing, and 1 / 3 of the phosphorus-free flame retardant was added at the same time. After the phosphorus-free flame retardant was completely applied, mixing was continued for 25 minutes. The material was sealed in a bag for 7 hours and fully reacted to obtain a mixture.

[0099] Example 21

[0100] The difference from Example 1 is that S2, mixed

[0101] The raw material was crushed into a powder with a particle size of 1.2 mm. 1 / 5 of the dispersant was applied every 12 minutes of mixing. At the same time, 1 / 3 of the phosphorus-free flame retardant was added. Mixing was continued for 30 minutes until the phosphorus-free flame retardant was completely applied. The material was sealed in a bag for 10 hours and fully reacted to obtain a mixture.

[0102] Example 22

[0103] The difference from Example 1 is that in step S2, the dispersant is composed of polycarboxylic acid with a mass concentration of 9%, ammonium stearate, and ethanol with a mass concentration of 4% in a mass ratio of 1:1:0.3.

[0104] Example 23

[0105] Different from Example 1, in step S2, the dispersant is composed of polycarboxylic acid with a mass concentration of 12%, ammonium stearate, and ethanol with a mass concentration of 6% in a mass ratio of 1.5:1:0.5.

[0106] Example 24

[0107] Different from Example 1, S3 and compression molding are carried out by ramming at a temperature of 170° C. and a pressure of 20 MPa.

[0108] Example 25

[0109] Different from Example 1, S3 and compression molding are carried out by ramming at a temperature of 180° C. and a pressure of 15 MPa.

[0110] Experimental example

[0111] For the carbon-modified phosphorus-free plastic prepared in each embodiment, 5 samples of each embodiment were taken and the flame retardant properties of the carbon-modified phosphorus-free plastic were tested using a vertical combustion apparatus. The average value of the 5 samples was taken for each performance measurement result. The results are as follows:

[0112] 1. Investigate the effects of components and component proportions on the flame retardant properties of carbon-modified phosphorus-free plastics

[0113] Table 1 Flame retardant properties of carbon-modified phosphorus-free plastics prepared in Examples 1 to 7 and Comparative Example 1

[0114]

[0115] The difference between Control Example 1 and Example 1 is that the phosphorus-free flame retardant is a commercially available nitrogen-based flame retardant;

[0116] Conclusion: It can be seen from the data in Table 1 that if the proportion of the components of the carbon-modified phosphorus-free plastic is too large or too small, the flame retardant properties of the phosphorus-free plastic will be slightly affected. Among them, the proportion and components of Example 1 are the optimal way; and through the comparison of the data of Example 1, Example 6, Example 7 and Example 1, it can be seen that although the nitrogen-based flame retardant can have a flame retardant effect, the flame retardant performance is much lower than that of Example 1, Example 6, and Example 7. This is because the carbon-forming accelerator A can act on the resin at high temperature to solidify it into carbon, thereby existing as a carbon source for the flame retardant. The carbon-forming accelerator B with the above components can effectively burn into metal compounds, which are loaded on porous carbon materials with a high specific surface area. It can be used as the main component of the carbon layer to significantly improve the flame retardant efficiency; at the same time, the carbon-forming accelerator B can also burn to produce a large amount of acidic gas as the acid source of the flame retardant. Therefore, the flame retardant effect of the nitrogen-based flame retardant in Example 1 is slightly worse than that of the phosphorus-free flame retardant in this scheme.

[0117] 2. Investigating the effect of the preparation method of the phosphorus-free flame retardant on the flame retardant properties of the carbon-modified phosphorus-free plastics Table 2 Flame retardant properties of the carbon-modified phosphorus-free plastics prepared in Example 1, Examples 8 to 13, and Comparative Example 2

[0118]

[0119] The difference between Control Example 2 and Example 1 is that, in step 3), the four-necked flask is heated to 100° C., the remaining amount of carbon-forming accelerator B is added to the four-necked flask, the temperature is further raised to 550° C., and the mixture is stirred for 30 min using a magnetic stirrer;

[0120] Conclusion: It can be seen from the data in Table 2 that the flame retardant properties of the carbon-modified phosphorus-free plastics are significantly affected by excessive or insufficient preparation parameters of the phosphorus-free flame retardant. By selecting a portion of the carbonization accelerator A from Examples 1 and 8 to 13 and heating it to 800°C first, the curing carbonization rate of the o-cresol resin to the resin can be higher, thereby supplementing the carbon source. At the same time, the carbonization accelerator B can be completely decomposed at 800°C, thereby more fully preparing the carbon-based material; and then the carbonization accelerator B decomposes at 400°C to absorb the heat on the surface of the burning material, thereby playing a flame retardant role, thereby enhancing the flame retardant effect of the phosphorus-free flame retardant; while in Control Example 2, the flame retardant properties of the carbon-modified phosphorus-free plastics are significantly deteriorated by calcining at a high temperature of 550°C. This is because melamine has been decomposed and no longer exists at this temperature, thereby affecting the flame retardant effect.

[0121] 3. Investigating the influence of the grafting process steps on the flame retardant properties of carbon-modified phosphorus-free plastics Table 3 Flame retardant properties of carbon-modified phosphorus-free plastics prepared in Example 1, Examples 14 to 19, and Comparative Examples 3 to 4

[0122]

[0123] The difference between Control Example 3 and Example 1 is that the cleaned carbonized layer is activated; the activation treatment method is as follows: using 25g of concrete as raw material, concrete, Portland cement, and fused magnesia are weighed according to a mass ratio of 1.8:0.9:0.6, fully stirred until molten, and then applied to the carbonized layer to a thickness of 0.8mm and cured for 13h;

[0124] The difference between Comparative Example 4 and Example 1 is that the nitrogen-containing compound is nitrogen trioxide;

[0125] Conclusion: From the data in Table 3, it can be seen that the process parameters of the grafting treatment have a small effect on the flame retardant effect of the phosphorus-free flame retardant. By comparing the data of Example 1, Examples 14 to 19 and Control Example 3, it can be seen that the flame retardant performance of Control Example 3 is slightly better than that of Example 1. This is because the activation treatment of the carbonized layer can enhance the surface activity, form pores, provide more adsorption sites, and thus enhance the grafting effect and further improve the flame retardant performance. From the data of Control Example 4, it can be seen that the flame retardant performance of the phosphorus-free flame retardant prepared in Control Example 4 is slightly poor. This is because the addition of amine compounds can further react the oxygen-containing groups on the surface of the carbon material to form a graft copolymer with flame retardant properties. At this time, the addition of nitrogen trioxide can further enhance the effect.

[0126] 4. Investigate the effect of dispersant composition on the flame retardant properties of carbon-modified phosphorus-free plastics

[0127] Table 4 Flame retardant properties of carbon-modified phosphorus-free plastics prepared in Example 1, Examples 20-25, and Comparative Example 5

[0128]

[0129] The difference between Control Example 5 and Example 1 is that the dispersant is composed of 10% polycarboxylic acid and ammonium stearate in a mass ratio of 1.2:1;

[0130] Conclusion: It can be seen from the data in Table 4 that the flame retardant properties of the phosphorus-free flame retardant prepared in Control Example 5 are poorer than those in Example 1 and Examples 20 to 25. This is because the addition of ethanol can promote ammonium stearate to quickly increase the viscosity and consistency of the dispersion, further improve the mixing efficiency of the mixture, and thus improve the flame retardant properties of the plastic.

Claims

1. A carbon-modified phosphorus-free plastic for improving flame retardancy, characterized in that: The invention comprises the following components by weight percentage: 60-80% of alumina clinker, 5-10% of composite fine powder, 4-6% of high-alumina cement, 5-7% of phosphorus-free flame retardant, 2-3% of dispersant and the balance of water; The composite fine powder is composed of 5 to 7 parts of SiO2 fine powder and 3 to 5 parts of active α-Al2O3 fine powder in parts by weight; The phosphorus-free flame retardant comprises the following raw materials, measured by weight: 15 to 17 parts of boric acid, 3 to 5 parts of epoxy resin, 3 to 5 parts of melamine, 1 to 1.5 parts of carbonization accelerator A, and 0.8 to 1 part of carbonization accelerator B; wherein the carbonization accelerator A is o-cresol-formaldehyde resin, and the carbonization accelerator B is a mixture of magnesium hydroxide and aluminum hydroxide in equal weight proportions; the dispersant is composed of polycarboxylic acid with a mass concentration of 9 to 12%, ammonium stearate, and ethanol with a mass concentration of 4 to 6%; The preparation method of the phosphorus-free flame retardant is: 1) taking carbon forming accelerator A and carbon forming accelerator B according to the ratio, spraying 99% anhydrous ethanol at a rate of 30 to 50 mL / min onto the surfaces of carbon forming accelerator A and carbon forming accelerator B, respectively, and then drying at room temperature and grinding carbon forming accelerator A and carbon forming accelerator B into particles with a particle size of 1 to 1.5 mm using a ball mill to obtain granular carbon forming accelerator A and granular carbon forming accelerator B; 2) putting epoxy resin into a crucible, adding granular carbonization accelerator A and 1 / 3 of granular carbonization accelerator B into the crucible in sequence, heating to 800-820° C., and ultrasonically vibrating for 15-20 minutes to obtain a carbon-based material; 3) Boric acid, melamine, and the carbon-based material prepared in step 2) are weighed according to the ratio and placed in a four-necked flask, the four-necked flask is heated to 85-100° C., the remaining amount of granular carbonization promoter B is added to the four-necked flask, the temperature is continued to rise to 350-400° C., and a magnetic stirrer is used to stir for 20-30 minutes to obtain a carbonized layer, which is a phosphorus-free flame retardant.

2. The carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 1, characterized in that: Step 2) The ultrasonic frequency is 18 to 20 kHz.

3. The carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 1, characterized in that: Performing a grafting treatment on the carbonized layer obtained in step 3); The grafting treatment method comprises: using a plasma treatment apparatus to clean the surface of the carbonized layer for 3 to 5 minutes; weighing the raw materials according to the mass ratio of carbonized layer: azobisisobutyronitrile: nitrogen-containing compound with a mass concentration of 30 to 40 mg / L of 3 to 5: 1 to 3: 0.5 to 1, and dividing the nitrogen-containing compound into n equal parts; The carbonized layer and azobisisobutyronitrile are placed in a reaction tube, the temperature of the reaction tube is adjusted to 40-45° C. and the pressure is 15-18 MPa, and an infrared lamp is used for irradiation. The mixture is stirred every 12-15 minutes and 1 / n of the nitrogen-containing compound is added until the nitrogen-containing compound is added; wherein 3≤n≤5.

4. The carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 3, characterized in that: The nitrogen-containing compound is prepared by mixing ethylenediamine or phenylenediamine with nitrogen trioxide or ammonium nitrate in any proportion.

5. The carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 3, characterized in that: The plasma processing parameters are: plasma power of 200-220W, plasma frequency of 35-38kHz, argon as the processing gas, and flow rate of 350-400sccm.

6. The method for preparing a carbon-modified phosphorus-free plastic for improving flame retardancy according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, premix At room temperature, alumina clinker was ground and sieved to obtain alumina clinker of three particle sizes: 5-3 mm, 3-1 mm, and ≤1 mm. The mixture obtained by mixing water and high-alumina cement was divided into 6 equal parts. Three parts of the mixture, two parts of the mixture, and one part of the mixture were added to the alumina clinker of the three particle sizes, respectively, for premixing. The premixing time was 5-8 minutes, and base material A, base material B, and base material C were obtained in turn. S2, mixed Base material A, base material B, base material C and composite fine powder are mixed and crushed into powdery raw materials. 1 / 3 to 1 / 5 of a dispersant is applied to the raw materials every 10 to 12 minutes using a double-roll mixer. 1 / 3 of a phosphorus-free flame retardant is added at the same time. Mixing is continued for 25 to 30 minutes until the phosphorus-free flame retardant is completely applied. The materials are sealed in a bag for 7 to 10 hours to fully react to obtain a mixture. S3, compression molding The mixed material is placed in a mold, and then rammed and formed under a temperature of 170-180° C. and a pressure of 15-20 MPa. The plastic material is then demolded to obtain the plastic material.

7. The method for preparing a carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 6, characterized in that: In step S2, the particle size of the powdered raw material is 1 to 1.2 mm.

8. The method for preparing a carbon-modified phosphorus-free plastic for improving flame retardancy according to claim 6, characterized in that: In step S2, polycarboxylic acid with a mass concentration of 9-12%, ammonium stearate, and ethanol with a mass concentration of 4-6% are composed in a mass ratio of 1-1.5:1:0.3-0.5.

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