Composite flame retardant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of materials, and discloses a composite flame retardant as well as a preparation method and application thereof. Carrying out first reaction on the DOPO grafted silane coupling agent and capsaicin to obtain a first reaction product; and carrying out a second reaction on melamine, cyanuric acid and the first reaction product, and carrying out freeze drying and grinding on the obtained second reaction product to obtain the composite flame retardant. The composite flame retardant can be used for preparing a polypropylene composite material. According to the invention, ammonium polyphosphate, dipentaerythritol and a composite flame retardant are utilized to form a rat-bite-proof intumescent flame-retardant system, and the rat-bite-proof intumescent flame-retardant polypropylene composite material is prepared through melt blending; the oxygen index of the composite material can meet the flame-retardant requirement, the problem that molten drops severely drop during combustion is solved, meanwhile, the irritation influence of capsaicin in the material is reduced, and the polypropylene composite material is endowed with the non-toxic and non-lethal avoidance effect.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a composite flame retardant and a preparation method and application thereof. Background Art

[0002] Polypropylene (PP) resin has excellent mechanical properties, heat resistance, chemical stability, and electrical insulation, and even has excellent electrical insulation in humid environments, so it is often used in electrical equipment cables. Mice are rodents with strong reproductive capacity and high survival ability. Their incisors are very developed and have the ability to continue to grow, so they need to grind hard objects to inhibit tooth growth, and the unique smell of plastics easily attracts mice. Therefore, PP cable sheaths are often damaged by mice, which is prone to short circuits, power outages and other accidents, and even serious electrical fires, causing immeasurable losses. Therefore, it is of great significance to develop flame retardants with rodent-proof properties.

[0003] Early traditional rodent repellents were toxic during the preparation and application of cables, which not only harmed workers, but also damaged the ecological environment and the food chain. Early cable materials mostly used halogen-containing flame retardants. With the development of diversified flame retardants, their shortcomings also emerged. The main problem was that halogen elements decomposed at high temperatures to release toxicity, causing harm to the human body and the environment.

[0004] As a green, ecological and environmentally friendly rodent repellent, capsaicin has been widely used in rodent and insect repellent. However, due to its volatility and strong irritation, it will affect the flame retardant properties and thermal stability of the materials during the processing of composite materials, and deteriorate the processing environment. Summary of the invention

[0005] In view of the problem that directly adding capsaicin to a polypropylene composite material will deteriorate the processing environment, the present invention provides a composite flame retardant and a preparation method and application thereof, which can effectively reduce the irritation effect of capsaicin and give the polypropylene composite material excellent anti-rat bite performance, flame retardant performance and thermal stability.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a composite flame retardant, wherein the method comprises the following steps:

[0007] (1) causing a first reaction between the DOPO grafted silane coupling agent and capsaicin to obtain a first reaction product;

[0008] (2) allowing melamine, cyanuric acid and the first reaction product to undergo a second reaction, and freeze-drying and grinding the obtained second reaction product to obtain the composite flame retardant.

[0009] The second aspect of the present invention provides a composite flame retardant prepared by the preparation method described in the first aspect.

[0010] The third aspect of the present invention provides use of the composite flame retardant described in the second aspect in preparing a polypropylene composite material.

[0011] The fourth aspect of the present invention provides a polypropylene composite material, wherein the composite material comprises the following raw materials in percentage by mass: 55-85% polypropylene, 10-25% ammonium polyphosphate, 1-20% dipentaerythritol, and 3-8% composite flame retardant;

[0012] Wherein, the composite flame retardant is the composite flame retardant described in the second aspect.

[0013] The fifth aspect of the present invention provides a method for preparing the composite material described in the fourth aspect, wherein the method comprises: melt blending polypropylene, ammonium polyphosphate, dipentaerythritol and a composite flame retardant to obtain a polypropylene composite material.

[0014] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0015] The invention utilizes ammonium polyphosphate, dipentaerythritol and a composite flame retardant to form an anti-rat bite expansion flame retardant system, and prepares a rat bite anti-rat bite expansion flame retardant polypropylene composite material through melt blending; the oxygen index of the composite material can meet the flame retardant requirement and solve the problem of severe dripping of molten droplets during combustion, while reducing the irritation effect of capsaicin in the material and giving the polypropylene composite material a non-toxic and non-lethal repellent effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the infrared spectrum of KHDC-MCA prepared in Example 1 of the present invention;

[0017] Figure 2 The TGA graph of KHDC-MCA prepared in Example 1 of the present invention; wherein (a) is the thermogravimetric analysis curve of MCA before and after modification; (b) is the differential thermogravimetric curve of MCA before and after modification;

[0018] Figure 3 Optical photograph of the specimen surface at the end of the rodent resistance test cycle. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] The first aspect of the present invention provides a method for preparing a composite flame retardant, wherein the method comprises the following steps:

[0021] (1) causing a first reaction between the DOPO grafted silane coupling agent and capsaicin to obtain a first reaction product;

[0022] (2) allowing melamine, cyanuric acid and the first reaction product to undergo a second reaction, and freeze-drying and grinding the obtained second reaction product to obtain the composite flame retardant.

[0023] In the present invention, the DOPO grafted silane coupling agent is combined with capsaicin through hydrogen bonding, which improves the encapsulation effect of capsaicin and can effectively delay the release time of peppers to achieve long-term rat prevention. Melamine (ME) reacts with cyanuric acid (CA) to generate melamine cyanurate (MCA), which is combined with the first reaction product through hydrogen bonding to enhance the encapsulation effect.

[0024] In some embodiments of the present invention, in step (1), the molar ratio of the DOPO grafted silane coupling agent to capsaicin is 5-15:1, preferably 10:1.

[0025] In some embodiments of the present invention, the temperature of the first reaction is 70-100°C, preferably 90°C.

[0026] In some embodiments of the present invention, the time of the first reaction is 1-4 hours, preferably 2 hours.

[0027] In some embodiments of the present invention, the capsaicin is selected from at least one of natural capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homocapsaicin and homodihydrocapsaicin.

[0028] In some embodiments of the present invention, the method for preparing the DOPO grafted silane coupling agent comprises: in a protective atmosphere, performing a grafting reaction between DOPO and a silane coupling agent to obtain the DOPO grafted silane coupling agent.

[0029] In some embodiments of the present invention, the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560) and γ-methacryloxypropyltrimethoxysilane (KH570).

[0030] In some embodiments of the present invention, the molar ratio of DOPO to the silane coupling agent is 1:1-3, preferably 1:2.

[0031] In some embodiments of the present invention, the conditions of the grafting reaction include: temperature of 140-150° C.; time of 5 hours.

[0032] In some embodiments of the present invention, the protective atmosphere gas is nitrogen.

[0033] In some embodiments of the present invention, in step (2), the molar ratio of melamine to cyanuric acid is 1:2-2:1, preferably 1:1.

[0034] In some embodiments of the present invention, the second reaction uses water as solvent.

[0035] In some embodiments of the present invention, the temperature of the second reaction is 75-100°C, preferably 90°C.

[0036] In some embodiments of the present invention, the time of the second reaction is 1-3 hours, preferably 2 hours.

[0037] In some embodiments of the present invention, the freeze-drying temperature is -5°C.

[0038] In some embodiments of the present invention, the freeze-drying time is 48 hours.

[0039] The second aspect of the present invention provides a composite flame retardant prepared by the preparation method described in the first aspect.

[0040] The third aspect of the present invention provides use of the composite flame retardant described in the second aspect in preparing a polypropylene composite material.

[0041] The composite flame retardant prepared by the present invention is used to prepare a polypropylene composite material, which can improve the anti-rat bite performance, flame retardant performance and thermal stability of the composite material.

[0042] The fourth aspect of the present invention provides a polypropylene composite material, wherein the composite material comprises the following raw materials in percentage by mass: 55%-85% polypropylene, 10%-25% ammonium polyphosphate, 1-20% dipentaerythritol, and 3-8% composite flame retardant;

[0043] Wherein, the composite flame retardant is the composite flame retardant described in the second aspect.

[0044] In some embodiments of the present invention, the composite material comprises the following raw materials in percentage by mass: 60-70% polypropylene, 15-21% ammonium polyphosphate, 4-15% dipentaerythritol, and 5% composite flame retardant.

[0045] In some embodiments of the present invention, the composite material comprises the following raw materials in percentage by mass: 70% polypropylene, 12.5-18.75% ammonium polyphosphate, 6.25-12.5% ​​dipentaerythritol, and 5% composite flame retardant.

[0046] In some embodiments of the present invention, the weight average molecular weight of the polypropylene is 80,000-180,000.

[0047] The fifth aspect of the present invention provides a method for preparing the composite material described in the fourth aspect, wherein the method comprises: melt blending polypropylene, ammonium polyphosphate, dipentaerythritol and a composite flame retardant to obtain a polypropylene composite material.

[0048] In some embodiments of the present invention, the melt blending conditions include: temperature of 170-180° C. and time of 10-15 min.

[0049] The present invention will be described in detail below through examples.

[0050] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0051] Sources:

[0052] Polypropylene: brand EPS30R, purchased from China Petrochemical Corporation;

[0053] Ammonium polyphosphate: Type II ammonium polyphosphate (DP>1000, industrial grade, Jinan Taixing Fine Chemical Co., Ltd.).

[0054] Example 1

[0055] This example is used to illustrate the preparation of the composite flame retardant KHDC1-MCA.

[0056] (1) DOPO (10.8 g, 0.05 mol) and KH550 (23 mL, 0.1 mol) were added to a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the mixture was reacted under anaerobic conditions for 5 h to obtain KHDOPO; then the mixture was cooled to 90°C, natural capsaicin (3.05 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC1 as a light yellow liquid;

[0057] (2) Melamine (ME, 12.612 g, 0.1 mol), cyanuric acid (CA, 12.903 g, 0.1 mol) and 50 mL of distilled water were placed in a 250 mL three-necked flask equipped with a stirrer, and the KHDC1 liquid obtained in step (1) was added, and the mixture was fully reacted at 90° C. for 2 h to obtain a milky white viscous liquid; the milky white viscous liquid was freeze-dried at -5° C. for 48 h, and ground to obtain a milky white powder, which was the composite flame retardant KHDC1-MCA.

[0058] Example 2

[0059] This example is used to illustrate the preparation of the composite flame retardant KHDC2-MCA.

[0060] (1) DOPO (10.8 g, 0.05 mol) and KH560 (22 mL, 0.1 mol) were added to a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the mixture was reacted under anaerobic conditions for 5 h to obtain KHDOPO; then the mixture was cooled to 90°C, dihydrocapsaicin (3.07 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC2 as a light yellow liquid;

[0061] (2) Melamine (ME, 12.612 g, 0.1 mol), cyanuric acid (CA, 12.903 g, 0.1 mol) and 50 mL of distilled water were placed in a 250 mL three-necked flask equipped with a stirrer, and the KHDC2 liquid obtained in step (1) was added, and the mixture was fully reacted at 90° C. for 2 h to obtain a milky white viscous liquid; the milky white viscous liquid was freeze-dried at -5° C. for 48 h, and ground to obtain a milky white powder, which was the composite flame retardant KHDC2-MCA.

[0062] Example 3

[0063] This example is used to illustrate the preparation of the composite flame retardant KHDC3-MCA.

[0064] (1) DOPO (10.8 g, 0.05 mol) and KH570 (23 mL, 0.1 mol) were added to a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the mixture was reacted under anaerobic conditions for 5 h to obtain KHDOPO; then the mixture was cooled to 90°C, and nordihydrocapsaicin (2.93 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC3, a light yellow liquid;

[0065] (2) Melamine (ME, 12.612 g, 0.1 mol), cyanuric acid (CA, 12.903 g, 0.1 mol) and 50 mL of distilled water were placed in a 250 mL three-necked flask equipped with a stirrer, and the KHDC3 liquid obtained in step (1) was added, and the mixture was fully reacted at 90° C. for 2 h to obtain a milky white viscous liquid; the milky white viscous liquid was freeze-dried at -5° C. for 48 h, and ground to obtain a milky white powder, which was the composite flame retardant KHDC3-MCA.

[0066] Comparative Example 1

[0067] DOPO (10.8 g, 0.05 mol) and KH550 (23 mL, 0.1 mol) were added to a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the reaction was carried out under anaerobic conditions for 5 h to obtain KHDOPO; then the mixture was cooled to 90°C, natural capsaicin (2.934 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC1 as a light yellow liquid; the light yellow powder obtained after freeze-drying was KHDC1.

[0068] Comparative Example 2

[0069] DOPO (10.8 g, 0.05 mol) and KH560 (22 mL, 0.1 mol) were added to a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the reaction was carried out under anaerobic conditions for 5 h to obtain KHDOPO; then the temperature was cooled to 90°C, dihydrocapsaicin (2.934 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC2 as a light yellow liquid; after freeze-drying, a light yellow powder was obtained, which was KHDC2.

[0070] Comparative Example 3

[0071] DOPO (10.8 g, 0.05 mol) and KH570 (23 mL, 0.1 mol) were added into a 100 mL three-necked flask equipped with a stirrer, nitrogen was introduced for 10 min, the temperature was raised to 140°C, and the reaction was carried out under anaerobic conditions for 5 h to obtain KHDOPO; then the mixture was cooled to 90°C, and dihydrocapsaicin (2.934 g, 0.01 mol) was added, and the mixture was stirred at 90°C for 2 h to obtain KHDC3 as a light yellow liquid; the light yellow powder obtained after freeze-drying was KHDC3.

[0072] Comparative Example 4

[0073] Take melamine (ME, 12.612 g, 0.1 mol), cyanuric acid (CA, 12.903 g, 0.1 mol) and 50 mL of distilled water in a 250 mL three-necked flask equipped with a stirrer, and fully react at 90°C for 2 h to obtain a white viscous liquid; after freeze-drying, a white powder is obtained, which is MCA.

[0074] Application Example 1

[0075] This application example is used to illustrate the preparation of a polypropylene composite material.

[0076] The composite material is composed of the following raw materials in percentage by mass: 70% polypropylene, 18.75% ammonium polyphosphate (APP), 6.25% dipentaerythritol (DPER), and 5% KHDC1-MCA composite flame retardant.

[0077] The preparation method is as follows:

[0078] Preheat the internal mixer to 175°C. After the temperature stabilizes, slowly add polypropylene. After the polypropylene is melted, slowly add ammonium polyphosphate, dipentaerythritol and composite flame retardant. Make sure all the raw materials are fully extruded, sheared and mixed evenly in the internal mixer at 20r / min. After mixing for 10 minutes, the rat-proof flame-retardant polypropylene composite material product is obtained.

[0079] Application Example 2

[0080] This application example is used to illustrate the preparation of a polypropylene composite material.

[0081] The composite material is composed of the following raw materials in percentage by mass: 70% polypropylene, 16.7% ammonium polyphosphate (APP), 8.3% dipentaerythritol (DPER), and 5% KHDC1-MCA composite flame retardant.

[0082] The preparation method is the same as that in Application Example 1.

[0083] Application Example 3

[0084] This application example is used to illustrate the preparation of a polypropylene composite material.

[0085] The composite material is composed of the following raw materials in percentage by mass: 70% polypropylene, 12.5% ​​ammonium polyphosphate (APP), 12.5% ​​dipentaerythritol (DPER), and 5% KHDC1-MCA composite flame retardant.

[0086] The preparation method is the same as that in Application Example 1.

[0087] Application Example 4

[0088] This application example is used to illustrate the preparation of a polypropylene composite material.

[0089] The composite material is composed of the following raw materials in percentage by mass: 70% polypropylene, 12.5% ​​ammonium polyphosphate (APP), 12.5% ​​dipentaerythritol (DPER), and 5% KHDC2-MCA composite flame retardant.

[0090] The preparation method is the same as that in Application Example 1.

[0091] Application Example 5

[0092] This application example is used to illustrate the preparation of a polypropylene composite material.

[0093] The composite material is composed of the following raw materials in percentage by mass: 70% polypropylene, 12.5% ​​ammonium polyphosphate (APP), 12.5% ​​dipentaerythritol (DPER), and 5% KHDC3-MCA composite flame retardant.

[0094] The preparation method is the same as that of Application Example 1.

[0095] Application Comparative Example 1

[0096] This comparative example provides a polypropylene composite material, which consists of 100% polypropylene by mass.

[0097] The preparation method is as follows: preheat the internal mixer to 175°C, slowly add polypropylene after the temperature stabilizes, and make the raw materials uniformly mixed by sufficient extrusion and shearing at 20r / min in the internal mixer; after mixing for 10 minutes, the polypropylene composite material product is obtained.

[0098] Application Comparative Example 2

[0099] This comparative example provides a polypropylene composite material, which consists of 70% of polypropylene and 30% of ammonium polyphosphate (APP) by mass percentage.

[0100] The preparation method is as follows: preheat an internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add ammonium polyphosphate, so that all raw materials are fully extruded, sheared and mixed uniformly in the internal mixer at 20r / min; after mixing for 10 minutes, a polypropylene composite material product is obtained.

[0101] Application Comparative Example 3

[0102] This comparative example provides a polypropylene composite material, which consists of 70% by weight of polypropylene and 30% by weight of dipentaerythritol (DPER).

[0103] The preparation method is as follows: preheat an internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add dipentaerythritol, so that all raw materials are fully extruded, sheared and mixed uniformly in the internal mixer at 20r / min; after mixing for 10 minutes, a polypropylene composite material product is obtained.

[0104] Application Comparative Example 4

[0105] This comparative example provides a polypropylene composite material, which consists of 70% by weight of polypropylene and 30% by weight of a KHDC1-MCA composite flame retardant.

[0106] The preparation method is as follows: preheat the internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add the KHDC1-MCA composite flame retardant, so that the raw materials are fully extruded, sheared and mixed uniformly in the internal mixer at 20r / min; after mixing for 10 minutes, the polypropylene composite material product is obtained.

[0107] Application Comparative Example 5

[0108] This comparative example provides a polypropylene composite material, which consists of 70% by weight of polypropylene and 30% by weight of a KHDC2-MCA composite flame retardant.

[0109] The preparation method is as follows: preheat the internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add the KHDC2-MCA composite flame retardant, so that all the raw materials are fully extruded, sheared and mixed uniformly in the internal mixer at 20r / min; after mixing for 10 minutes, the polypropylene composite material product is obtained.

[0110] Application Comparative Example 6

[0111] This comparative example provides a polypropylene composite material, which consists of 70% by weight of polypropylene and 30% by weight of a KHDC3-MCA composite flame retardant.

[0112] The preparation method is as follows: preheat the internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add the KHDC3-MCA composite flame retardant, so that all the raw materials are fully extruded, sheared and mixed uniformly in the internal mixer at 20r / min; after mixing for 10 minutes, the polypropylene composite material product is obtained.

[0113] Application Comparative Example 7

[0114] This comparative example provides a polypropylene composite material, which consists of 70% by weight of polypropylene and 30% by weight of an MCA composite flame retardant.

[0115] The preparation method is as follows: preheat the internal mixer to 175°C, and after the temperature stabilizes, slowly add polypropylene, and after the polypropylene is added, slowly add the MCA composite flame retardant, so that all the raw materials are fully extruded, sheared and mixed evenly in the internal mixer at 20r / min; after mixing for 10 minutes, the polypropylene composite material product is obtained.

[0116] Test Example 1

[0117] Figure 1 This is the infrared spectrum of the composite flame retardant KHDC-MCA in Example 1.

[0118] It can be seen from the figure that after DOPO was grafted with KH550, 2433cm -1 The pH absorption peak at 1581 cm-1 obviously disappeared, proving that DOPO was successfully modified by KH550. KHDOPO has characteristic absorption peaks related to DOPO and KH550, such as DOPO at 1581 cm-1. -1 The NH absorption peak at 1056 cm -1After adding capsaicin, KHDOPO encapsulates capsaicin, and there is a peak of Si-O absorption at 1646 cm in KHDC. -1 The C=C functional group at the position indicates that KHDOPO successfully encapsulates capsaicin. After the modification of MCA, the peak shape of the characteristic peak of MCA remains basically unchanged, and only the peak intensity changes, indicating that KHDC and MCA are hydrogen-bonded, and the composite flame retardant KHDC-MCA is successfully prepared.

[0119] Test Example 2

[0120] Figure 2 This is the TGA curve of the composite flame retardant KHDC1-MCA in Example 1.

[0121] It can be seen that compared with MCA, the residual carbon content of KHDC1-MCA is significantly increased. This is because MCA produces NH at high temperature. 3 In Figures (a) and (b), KHDC-MCA is in multiple decomposition stages, indicating that after modification by KHDC, the MCA surface is obviously coated, KH550 and DOPO act on the condensed phase flame retardant, and effectively improve the formation of the carbon layer of the polypropylene matrix. Therefore, the residual carbon content of KHDC-MCA in Figure a reaches 33.41%.

[0122] Test Example 3

[0123] The polypropylene composite materials prepared in Application Examples 1-3 and Comparative Examples 1-4 were subjected to vertical combustion, limiting oxygen index test and biological rodent-proof test.

[0124] The vertical combustion test is carried out according to UL-94 (ANSI / ASTMD635-77), and the size of each sample is 125×12.5×3.2mm. In the evaluation level, V-0 means that the vertical sample stops burning within 10s, and no droplets are allowed; V-1 means that the vertical sample stops burning within 30s, and no droplets are allowed; V-2 means that the vertical sample stops burning within 30s, and dripping of burning materials is allowed; NR means no level.

[0125] The limiting oxygen index is measured using an oxygen index meter according to LOI (ASTM D2863-97), and the size of each sample is 120×6.5×3.2mm. This project tests the minimum oxygen concentration when each material just maintains balanced combustion. For flame retardant materials, the higher the index, the better.

[0126] According to GB / T 34016-2017, the repellent effect of the composite flame retardant was evaluated based on the consumption of the composite material by SD rats after 14 days. The weight of the composite material and the body weight of the rats were recorded every 24 h. All experiments were conducted in accordance with the ethical provisions of Chinese law and the Guide for the Care and Use of Laboratory Animals in China.

[0127] The performance test results are shown in Table 1.

[0128] Table 1

[0129]

[0130]

[0131] Depend on Figure 3 As can be seen from Table 1, 5% of the composite flame retardant was added to the application examples 1-3. In the rat bite test, it showed an excellent non-lethal avoidance effect, the strips were complete, the rat protection rate reached 95% and above, and the protection level reached a significant level. In the flame retardant performance test, the composite flame retardant in the application examples 1-3 synergistically flame retarded with ammonium polyphosphate and dipentaerythritol, so that the limiting oxygen index reached 29% and above, which belonged to the flame retardant grade. After the vertical burning test, they all reached the V-0 level without molten droplets. However, the application examples 1-3 were not added with the addition of composite flame retardants. During the rat bite test cycle, they were severely bitten by rats, the rat protection rate was less than 0.25, and the protection level was unqualified. While the application examples 4-6, which only added composite flame retardants, had a high rat protection rate and a significant protection level, but the flame retardant performance was poor, and a high limiting oxygen index could not be shown, and it was difficult to pass the vertical burning test. In the application example 7, unmodified MCA was added, which had no rat-proof effect and poor flame retardant performance.

[0132] The present invention forms an expansion flame retardant system by using ammonium polyphosphate, KHDC-MCA and dipentaerythritol, and prepares a rat-proof expansion flame retardant polypropylene composite material by melt blending. The product has good flame retardant performance and thermal stability, and the oxygen index of the composite material can meet the flame retardant requirements, and solves the problem of molten droplets; at the same time, the polypropylene material is endowed with excellent non-toxic and non-lethal rat-proof effect. The rat-proof performance of the polypropylene composite material product prepared by the present invention is more green and environmentally friendly.

[0133] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a composite flame retardant, characterized in that: The method comprises the following steps: (1) causing a first reaction between the DOPO grafted silane coupling agent and capsaicin to obtain a first reaction product; (2) allowing melamine, cyanuric acid and the first reaction product to undergo a second reaction, and freeze-drying and grinding the obtained second reaction product to obtain the composite flame retardant.

2. The method according to claim 1, wherein: In step (1), the molar ratio of DOPO grafted silane coupling agent to capsaicin is 5-15:1, preferably 10:1; Preferably, the temperature of the first reaction is 70-100°C, preferably 90°C; Preferably, the first reaction time is 1-4h, preferably 2h; Preferably, the capsaicin is selected from at least one of natural capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homocapsaicin and homodihydrocapsaicin.

3. The method according to claim 1 or 2, wherein: The preparation method of the DOPO grafted silane coupling agent comprises: in a protective atmosphere, carrying out a grafting reaction between DOPO and a silane coupling agent to obtain the DOPO grafted silane coupling agent; Preferably, the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane; Preferably, the molar ratio of DOPO to the silane coupling agent is 1:1-3, preferably 1:2; Preferably, the conditions of the grafting reaction include: temperature of 140-150°C; time of 5h; Preferably, the protective atmosphere gas is nitrogen.

4. The method according to any one of claims 1 to 3, wherein: In step (2), the molar ratio of melamine to cyanuric acid is 1:2-2:1, preferably 1:1; Preferably, the second reaction uses water as solvent; Preferably, the temperature of the second reaction is 75-100°C, preferably 90°C; Preferably, the second reaction time is 1-3 h, preferably 2 h.

5. The method according to any one of claims 1 to 4, wherein: The freeze drying temperature is -5°C; Preferably, the freeze-drying time is 48 hours.

6. The composite flame retardant prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the composite flame retardant according to claim 6 in the preparation of polypropylene composite materials.

8. A polypropylene composite material, characterized in that: The composite material comprises the following raw materials in percentage by mass: 55-85% polypropylene, 10-25% ammonium polyphosphate, 1-20% dipentaerythritol, and 3-8% composite flame retardant; Wherein, the composite flame retardant is the composite flame retardant according to claim 6.

9. The composite material according to claim 8, wherein The composite material comprises the following raw materials in percentage by mass: 60-70% polypropylene, 15-21% ammonium polyphosphate, 4-15% dipentaerythritol, and 5% composite flame retardant; Preferably, the composite material comprises the following raw materials in percentage by mass: 70% polypropylene, 12.5-18.75% ammonium polyphosphate, 6.25-12.5% ​​dipentaerythritol, and 5% composite flame retardant; Preferably, the weight average molecular weight of the polypropylene is 80,000-180,000.

10. A method for preparing the composite material according to claim 8 or 9, characterized in that: The method comprises: melt-blending polypropylene, ammonium polyphosphate, dipentaerythritol and a composite flame retardant to obtain a polypropylene composite material; Preferably, the melt blending conditions include: temperature of 170-180° C. and time of 10-15 min.

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