Lignin type three-in-one flame retardant, fireproof coating and preparation method of lignin type three-in-one flame retardant

Abstract

The invention provides a lignin type three-in-one flame retardant, a fireproof coating and a preparation method of the lignin type three-in-one flame retardant, and belongs to the field of fire prevention. According to the technical scheme, the flame retardant is prepared from the following raw materials: ammonium polyphosphate, pentaerythritol and lignin; the fireproof coating comprises a flame retardant, epoxy resin and polyamide resin. The preparation method has the beneficial effects that the lignin type three-in-one flame retardant is prepared from the ammonium polyphosphate, the pentaerythritol and the lignin, and meanwhile, the epoxy resin and the polyamide resin are combined for use, so that on one hand, greenness of the composite flame-retardant material is realized, and on the other hand, the composite flame-retardant material can inhibit or delay combustion; the purpose of reducing heat transfer of external fire heat radiation to the base material is achieved, and therefore heat protection of the base material is achieved.

Description

Technical Field

[0001] The invention relates to the field of fire prevention, and in particular to a lignin-based three-in-one flame retardant, a fire-retardant coating and a preparation method thereof. Background Art

[0002] Fire is an important part of the development of human civilization. While human production is constantly improving and driving history forward, uncontrolled fires in time and space may also threaten public safety and cause waste of social resources. Therefore, reducing the danger caused by fire is important for human safety and development. Organic synthetic materials have developed rapidly in recent years. Rubber, plastics and synthetic fibers made on the basis of polymers are widely used in national defense, industry, agricultural production and people's daily life. Most organic synthetic materials are easy to burn and produce gases that are harmful to the human body when burning. Adding flame retardants to polymers is one of the strategic measures to reduce the occurrence of fires.

[0003] Epoxy resin (EP) is a polymer material widely used in the automotive, electronics, plastic products and other industries. EP is extremely flammable and has poor thermal stability. It releases a lot of heat and smoke during combustion, increasing the risk of fire. Therefore, it is necessary to conduct flame retardant research on EP. In recent years, halogen-free intumescent flame retardants (IFR) have been widely used to improve the flame retardant properties of EP. In order to obtain a suitable flame retardant effect, a large amount of IFR is usually required, which not only increases investment but also affects product performance. If the raw materials come from nature, it can save costs and reduce damage to the environment. Among them, biomass resources are abundant, cheap and easy to obtain, low in pollution, renewable, and most biomass resources have a high carbon content, which can achieve the greening of flame retardants within a certain limit. Summary of the invention

[0004] The object of the present invention is to provide a lignin-type three-in-one flame retardant prepared by ammonium polyphosphate, pentaerythritol and lignin, and used in combination with epoxy resin and polyamide resin, so as to realize the greening of composite flame retardant materials on the one hand, and at the same time ensure that the composite flame retardant materials can inhibit or delay combustion, so as to achieve the purpose of reducing the heat transfer from external fire heat radiation to the substrate, thereby realizing the thermal protection of the substrate. Lignin-type three-in-one flame retardant, fire retardant coating and preparation method thereof.

[0005] The present invention is achieved by the following measures: A lignin-based three-in-one flame retardant, characterized in that the flame retardant is made of the following raw materials: ammonium polyphosphate, pentaerythritol, and lignin.

[0006] The specific features of the present invention also include: The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.5.

[0007] The preparation method of the flame retardant comprises the following steps: S1. Put ammonium polyphosphate, pentaerythritol and lignin into a three-necked flask in a ratio of 2:1:0.5, and then add 50% anhydrous ethanol to dissolve; S2, placing the three-necked flask in step S1 in a constant temperature water bath, maintaining the temperature at 80°C, stirring with a constant speed stirrer, stirring and reacting for 3 hours, and then standing and cooling to room temperature; S3. Filter and wash the sample after cooling in step S2, and then place it in an oven at 80° C. to dry for 48 hours. Grind the dried sample to obtain the final product, a lignin trinity intumescent flame retardant.

[0008] The constant speed stirrer has a rotation speed of 300 r / min.

[0009] An epoxy intumescent fireproof coating, characterized in that it comprises the flame retardant according to claims 1 to 4 as well as epoxy resin and polyamide resin.

[0010] The method for preparing the fire retardant coating comprises the following steps: (1) Weigh a certain amount of flame retardant, mix the flame retardant with epoxy resin, and then add anhydrous ethanol to dilute to obtain a mixture; (2) Grinding the mixture obtained in step (1) using a conical mill until the particle size of the sample is less than 20 μm, adding polyamide resin (PA) to the ground mixture, and stirring to obtain a liquid mixture; (3) Pour the liquid mixture obtained in step (2) into a mold and cure it in a forced air drying oven at 60° C. for 72 hours to obtain an epoxy intumescent fire retardant coating.

[0011] The ratio of epoxy resin (EP), polyamide resin (PA) and lignin-type trinity flame retardant is 48:32:20.

[0012] The epoxy resin and the polyamide resin were both heated in a 60° C. water bath for 20 min before use.

[0013] The beneficial effects of the present invention are as follows: the present invention prepares a lignin-type three-in-one flame retardant through ammonium polyphosphate, pentaerythritol and lignin, and uses it in combination with epoxy resin and polyamide resin, thereby realizing the greening of the composite flame retardant material on the one hand, and ensuring that the composite flame retardant material can inhibit or delay combustion, thereby achieving the purpose of reducing the heat transfer from external fire heat radiation to the substrate, thereby realizing thermal protection of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1This is a chemical structure analysis diagram of the lignin-based three-in-one flame retardant using an infrared spectrometer in Experiment 1 of the present invention.

[0015] Figure 2 Graph showing HRR and THR in a cone calorimeter experiment of the present invention.

[0016] Figure 3 The graph is a graph of total smoke production (TSP) and smoke production rate (SPR) in a cone calorimeter experiment of the present invention.

[0017] Figure 4 It is a curve diagram of TG and DTG of the epoxy intumescent fire retardant coating in the thermogravimetric analysis experiment of the present invention. DETAILED DESCRIPTION

[0018] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0019] Example 1 A lignin-based three-in-one flame retardant is prepared from the following raw materials: ammonium polyphosphate, pentaerythritol and lignin.

[0020] The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.5.

[0021] Example 2 A lignin-based three-in-one flame retardant is prepared from the following raw materials: ammonium polyphosphate, pentaerythritol and lignin.

[0022] The specific features of the present invention also include: The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.5.

[0023] The preparation method of the flame retardant comprises the following steps: S1. Put ammonium polyphosphate, pentaerythritol and lignin into a three-necked flask in a ratio of 2:1:0.5, and then add 50% anhydrous ethanol to dissolve; S2, placing the three-necked flask in step S1 in a constant temperature water bath, maintaining the temperature at 80°C, stirring with a constant speed stirrer, stirring and reacting for 3 hours, and then standing and cooling to room temperature; S3. Filter and wash the sample after cooling in step S2, and then place it in an oven at 80° C. to dry for 48 hours. Grind the dried sample to obtain the final product, a lignin trinity intumescent flame retardant.

[0024] The constant speed stirrer has a rotation speed of 300 r / min.

[0025] Example 3 A lignin-based three-in-one flame retardant is prepared from the following raw materials: ammonium polyphosphate, pentaerythritol and lignin.

[0026] The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.5 An epoxy intumescent fireproof coating comprises the flame retardant according to claims 1 to 4, epoxy resin and polyamide resin.

[0027] Example 4 A lignin-based three-in-one flame retardant is prepared from the following raw materials: ammonium polyphosphate, pentaerythritol and lignin.

[0028] The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.5 An epoxy intumescent fireproof coating, comprising the flame retardant according to claims 1 to 4, epoxy resin and polyamide resin; The method for preparing the fire retardant coating comprises the following steps: (3) Weigh a certain amount of flame retardant, mix the flame retardant with epoxy resin, and then add anhydrous ethanol to dilute to obtain a mixture; (6) Grind the mixture obtained in step (1) using a conical mill until the particle size of the sample is less than 20 μm, add the polyamide resin (PA) to the ground mixture, and stir to obtain a liquid mixture; (3) Pour the liquid mixture obtained in step (2) into a mold and cure it in a forced air drying oven at 60° C. for 72 hours to obtain an epoxy intumescent fire retardant coating.

[0029] The ratio of epoxy resin (EP), polyamide resin (PA) and lignin-type trinity flame retardant is 48:32:20.

[0030] The epoxy resin and the polyamide resin were both heated in a 60° C. water bath for 20 min before use.

[0031] Experiment 1: Flame retardant chemical structure analysis experiment The chemical structure of the lignin-based trinity flame retardant was analyzed using an infrared spectrometer, with an infrared wavenumber detection range of 500-4000 cm-1 and a sample mass of 10-15 mg; like Figure 1As described above, the broad peak near 3343 cm-1 is caused by the stretching vibration of -OH associated within the molecule, the absorption peak at 3217 cm-1 mainly comes from multi-molecular associated H2O, the absorption peak near 1673 cm-1 is attributed to the vibration of the C=O group, the peak at 2700 cm-1 corresponds to the stretching vibration peak of -CH, which comes from -CHO, and the peaks at 1163 cm-1, 1004 cm-1, 898 cm-1 and 776 cm-1 come from -CO- and -PO-, indicating that the lignin-type trinity flame retardant is successfully polymerized.

[0032] Experiment 2: Epoxy intumescent fire retardant coating ratio experiment Experimental preparation: According to different mass ratios of epoxy resin (EP), polyamide resin (PA) and flame retardant, five groups of epoxy intumescent fire retardant coating samples were prepared as shown in Table 1; Table 1 Formula of epoxy intumescent fire retardant coating

[0033] The limiting oxygen index (LOI) of the sample was measured in a mixture of oxygen and nitrogen using an oxygen index analyzer, and the sample size was 100 mm × 6.5 mm × 3.2 mm. The flame propagation on the material surface was tested using a vertical combustion instrument, and the sample size was 130 mm × 13 mm × 3.2 mm. As can be seen from Table 2, the LOI of pure EP is only 19.5%, and it is accompanied by the generation of molten droplets, and it fails the UL-94 test; The LOI value of EP-1 and EP-2 is 23.5%. Although they did not pass the UL-94 test, no droplets were generated, and the overall flame retardant performance was improved compared to Pure EP. The LOI of EP-3 and EP-4 are 25.5% and 26.5% respectively, and both have reached the V-0 level in UL-94. The lignin-based trinity flame retardant burns to form a dense carbon layer, which has a physical barrier protection effect and can inhibit the air and heat in the environment from entering the substrate during the combustion process, thereby improving the flame retardant properties of the material.

[0034] Table 2 LOI and UL-94 test results of epoxy intumescent fire retardant coating

[0035] NR:No rating Cone calorimeter experiment: The specimens were tested according to the ISO 5660-1 test standard, with a thermal radiation power of 35 kW / m2 and a sample size of 100 mm × 100 mm × 3 mm.

[0036] The HRR and THR curves of the epoxy intumescent fire retardant coating tested at a thermal radiation power of 35 kW / m2 are shown in Figure 2. Figure 2 As shown, typical data are shown in Table 3. Figure 2 From the data in (a), we can see that compared with pure EP, the ignition time (TTI) of the sample with flame retardant added is prolonged, and the pHRR is significantly reduced, from a minimum of 1292.79 kW / m2 to 230.12 kW / m2, a decrease of 82.20%. The addition of flame retardant not only reduces pHRR, but also broadens the heat release rate peak. In order to comprehensively compare the flame retardant properties of the samples, the fire performance index (FPI) is introduced here. FPI is defined as the ratio of TTI to pHRR. This index can estimate both the spread speed of the fire and the scale of the fire. The smaller the FPI, the easier it is for the material to flash over, and the greater the fire hazard. The FPI of EP-4 is 712.5% ​​higher than that of pure EP, and the fire hazard is greatly reduced.

[0037] The curve of THR changing with time is as follows Figure 2 As shown in the data (b), the THR of the samples with flame retardants added was significantly reduced. Compared with Pure EP, the THR of EP-1, EP-2, EP-3 and EP-4 were reduced by 38.07%, 49.84%, 78.20% and 78.27%, respectively. The average effective heat of combustion (av-EHC) of EP-4 was 47.85 MJ / kg, which was 51.27% lower than that of Pure EP, the largest decrease.

[0038] Table 3 Typical data of material combustion in cone calorimeter experiment

[0039] The total smoke production (TSP) and smoke production rate (SPR) curves during combustion are as follows: Figure 3 As shown in Table 3, the specific data show that the TSP and peak smoke release rate (pSPR) of the samples decreased significantly after adding flame retardants. Compared with Pure EP, the pSPR of EP-1, EP-2, EP-3 and EP-4 decreased by 47.62%, 64.76%, 65.71% and 70.95%, respectively. Compared with EP-1, the TSP of EP-4 decreased from 21.26 m2 to 6.59 m2, a decrease of 69%, and the total mass loss (TML) was the smallest, at 43.91wt%.

[0040] Thermogravimetric analysis experiment: In order to study the pyrolysis behavior of the coating, a thermogravimetric analysis experiment was carried out using a synchronous thermal analyzer in a nitrogen atmosphere at 30°C-700°C, a heating rate of 20°C / min, and a sample mass of 10-15 mg.

[0041] TG and DTG curves of epoxy intumescent fire retardant coatings are as follows: Figure 4 As shown, typical data are shown in Table 4. As can be seen from Table 4, the peak mass loss rate and the corresponding temperature of the sample after adding the flame retardant are significantly reduced, and the residual carbon rate increases, indicating that the addition of flame retardants can improve the heat resistance of the composite material. Figure 4 It can be seen that the flame retardant EP is decomposed in one step, and the thermal stability of the flame retardant EP is significantly higher than that of the Pure EP. The flame retardant EP sample begins to lose mass in the range of 100-300℃, and the decomposition rate increases slowly. At around 300℃, it enters the second stage, and the mass of the sample decreases sharply. Pure EP reaches the peak mass loss rate at 407.06℃, and the flame retardant EP reaches the peak mass loss rate at around 370℃. Compared with Pure EP, the residual carbon rate of EP-4 increased by 100.52%, and the peak mass loss rate decreased by 94.57%. The phosphoric acid derivatives formed by the thermal decomposition of APP react with free radicals to form stable compounds, which reduces the free radical chain reaction rate of the combustion reaction. Lignin and PER contain a large number of hydroxyl groups. A large number of water molecules will be produced during the cracking process of APP. The evaporation of water molecules will absorb a lot of heat, thereby slowing down the combustion reaction. Lignin has a high carbon content and works together with PER to promote the formation of the carbon layer.

[0042] Table 4 TG typical data of epoxy intumescent fire retardant coating Tab. 2 TG typical data of epoxy intumescent coating

[0043] Technical features not described in the present invention can be achieved through or by adopting existing technologies and will not be described in detail here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

[0044] Through the above experiments and considering the economic benefits, when the EP:PA:flame retardant is 48:32:20, it is the optimal ratio. The limiting oxygen index (LOI) of the material is 26.5%, the material passes the UL-94 V-0 grade, the total mass loss (TML) is as low as 43.91 wt%, the maximum heat release rate (pHRR) is 82.20% lower than that of pure EP, the fire performance index (FPI) is increased by 712.5%, the peak smoke release rate (pSPR) is reduced by 70.95%, and the total smoke generation (TSP) is reduced by 69%. During combustion, the flame retardant can inhibit or delay combustion, thereby reducing the heat transfer from external fire heat radiation to the substrate, thereby achieving thermal protection of the substrate, and can also play the role of oxygen isolation and smoke suppression, buying time for accident control and emergency rescue.

Claims

1. A lignin-based trinity flame retardant, characterized in that: The flame retardant is made of the following raw materials: ammonium polyphosphate, pentaerythritol and lignin.

2. The lignin-based trinity flame retardant according to claim 1, characterized in that: The ratio of the ammonium polyphosphate, the pentaerythritol and the lignin is 2:1:0.

5.

3. The lignin-based trinity flame retardant according to claim 2, characterized in that: The preparation method of the flame retardant comprises the following steps: S1. Put ammonium polyphosphate, pentaerythritol and lignin into a three-necked flask in a ratio of 2:1:0.5, and then add 50% anhydrous ethanol to dissolve; S2, placing the three-necked flask in step S1 in a constant temperature water bath, maintaining the temperature at 80°C, stirring with a constant speed stirrer, stirring and reacting for 3 hours, and then standing and cooling to room temperature; S3. Filter and wash the sample after cooling in step S2, and then place it in an oven at 80° C. to dry for 48 hours. Grind the dried sample to obtain the final product, a lignin trinity intumescent flame retardant.

4. The lignin-based three-in-one flame retardant according to claim 3, characterized in that: The constant speed agitator has a rotation speed of 300 r / min.

5. An epoxy intumescent fire retardant coating, characterized in that: The invention comprises the flame retardant according to claims 1 to 4, epoxy resin and polyamide resin.

6. The epoxy intumescent fire retardant coating according to claim 4, characterized in that: The method for preparing the fire retardant coating comprises the following steps: (1) Weigh a certain amount of flame retardant, mix the flame retardant with epoxy resin, and then add anhydrous ethanol to dilute to obtain a mixture; (2) Grinding the mixture obtained in step (1) using a conical mill until the particle size of the sample is less than 20 μm, adding the polyamide resin to the ground mixture, and stirring to obtain a liquid mixture; (3) Pour the liquid mixture obtained in step (2) into a mold and cure it in a forced air drying oven at 60° C. for 72 hours to obtain an epoxy intumescent fire retardant coating.

7. The epoxy intumescent fire retardant coating according to claim 6, characterized in that: The ratio of epoxy resin (EP), polyamide resin (PA) and lignin-type trinity flame retardant is 48:32:

20.

8. The epoxy intumescent fire retardant coating according to claim 7, characterized in that: The epoxy resin and the polyamide resin were both heated in a 60° C. water bath for 20 min before use.

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