Flame-retardant temperature-resistant shielding material and preparation method thereof

Abstract

The invention discloses a flame-retardant temperature-resistant shielding material and a preparation method thereof, and the flame-retardant temperature-resistant shielding material is composed of the following components: 13-20 wt% of phenolic resin composite powder, 0.5-8 wt% of boron carbide powder, 70-85 wt% of lead powder, 1-5 wt% of a reinforcing agent and 0.1-0.2 wt% of a lubricant. Wherein the phenolic resin composite powder is a mixture prepared from common phenolic resin and boron phenolic resin. The cable has heat resistance, flame retardance, shielding performance, thermal performance and mechanical performance, and can provide excellent comprehensive performance so as to ensure protection safety and structural safety.

Description

Technical Field

[0001] The present invention relates to the technical field of shielding materials, in particular to a flame retardant and heat resistant shielding material and a preparation method thereof. Background Art

[0002] In the reactor compartment area, some shielded areas are characterized by high temperature, strong radiation, small space and high safety. The local ambient temperature is as high as 250°C. In addition, the space in this area is small and the radiation dose rate is large. Ordinary polymer materials such as lead-boron polyethylene are difficult to meet the use requirements in terms of heat resistance, flame retardancy and radiation resistance.

[0003] In order to ensure the safety of the nuclear reactor shielding system, a composite shielding material with excellent temperature resistance, flame retardancy and mechanical properties, and capable of shielding neutrons and gamma rays, is needed. This shielding material can be directly used in the high-temperature area of ​​the shielding area, which can significantly simplify the shielding structure and improve the safety of the shielding system.

[0004] Commonly used lead-boron polyethylene materials have good shielding properties, but due to the limitations of the polyethylene substrate, the maximum operating temperature generally does not exceed 130°C, and the flame retardant performance is poor. The invention patent application CN201310294900.7 "A heat-resistant composite shielding material and its preparation method" mentions that the heat deformation temperature can be increased to 120°C when polypropylene is used as the substrate, while the heat deformation temperature of the lead-boron polyethylene material is only 82°C. However, the patent still does not solve the flame retardant problem of polypropylene, and the heat resistance and mechanical properties of polypropylene cannot meet the requirements of the use environment. Invention patent ZL202110191196.7 "Castable epoxy-based heat-resistant shielding material and its preparation method and application" uses epoxy resin as the substrate, adds neutron-proof additives and flame retardant additives, and its heat resistance is increased to 120-150°C, and the oxygen index is increased to 27, but the system has a low density and poor γ shielding performance, and its heat resistance still does not meet the requirements of the use environment. Invention patent CN201310092036.2 "A high temperature resistant shielding material with comprehensive neutron and gamma shielding effect" mentions the use of epoxy resin, boron carbide and lead powder to make a heat resistant shielding material with a temperature resistance of 220°C, but epoxy resin is a flammable material with an oxygen index of about 18, so the flame retardant performance of the heat resistant shielding material is poor and cannot meet the use requirements. Invention patent CN202110887236.1 "A high flame retardant, high bonding strength high temperature resistant shielding putty" mentions the use of epoxy resin to add alicyclic amine curing agent, with aluminum hydroxide flame retardant, boron carbide, lead powder shielding aids to prepare a shielding putty material with an oxygen index of up to 34 and a density of 3.4g / cm3. If the density is increased to 4.95g / cm3, its oxygen index drops to 26, and due to the limitations of the epoxy resin system, its long-term use temperature does not exceed 160°C. In summary, the existing shielding materials cannot meet the requirements of the existing use environment in terms of temperature resistance and flame retardancy. Summary of the invention

[0005] To this end, the technical problem to be solved by the present invention is to provide a flame retardant and heat resistant shielding material with a temperature resistance of more than 250°C and excellent flame retardant properties and a preparation method thereof, which takes into account heat resistance, flame retardant properties, shielding properties, thermal properties, and mechanical properties, and can provide excellent comprehensive performance to ensure protective safety and structural safety.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A flame retardant and heat resistant shielding material is composed of the following components: 13-20wt% of phenolic resin composite powder, 0.5-8wt% of boron carbide powder, 70-85wt% of lead powder, 1-5wt% of reinforcing agent and 0.1-0.2wt% of lubricant; wherein the phenolic resin composite powder is a mixture of ordinary phenolic resin and boron phenolic resin.

[0008] In the flame-retardant and heat-resistant shielding material, in the phenolic resin composite powder, the weight ratio of ordinary phenolic resin to boron phenolic resin is 1:1-4.

[0009] The reinforcing agent of the flame retardant and heat resistant shielding material is glass fiber powder.

[0010] In the flame-retardant and heat-resistant shielding material, the fiber length of the glass fiber powder is 0.1 to 3 mm.

[0011] The lubricant of the flame retardant and heat resistant shielding material is calcium stearate and / or zinc stearate.

[0012] The flame retardant and heat resistant shielding material has a density of 4.0 to 5.5 g / cm 3 .

[0013] The lead powder of the flame-retardant and heat-resistant shielding material has a particle size of 300 to 500 meshes and a purity greater than or equal to 99.4wt%.

[0014] In the flame-retardant and heat-resistant shielding material, the particle size of the boron carbide powder is less than or equal to 100 μm.

[0015] The preparation method of the flame retardant lead-boron modified polyethylene composite material comprises the following steps:

[0016] Step 1) mixing: weighing the phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant and mixing them in a dry powder mixer to obtain a mixed powder, with a rotation speed of 20 to 60 r / min and a mixing time of 2 to 120 min; during the mixing process, the rotation direction can be adjusted 1 to 2 times, so that the components can be mixed more evenly, thereby improving the uniformity of distribution of the components in the finished product;

[0017] Step 2) Molding: Weigh the mixed powder obtained in step 1) and put it into a mold for pressing to obtain a flame retardant and heat resistant shielding material. The pressing temperature is 170-200°C, the pressing time is 15-100 minutes, and the pressing pressure is 10-20 MPa.

[0018] In the above preparation method, in step 2), the specific pressing operation is:

[0019] Step 2-1) pre-pressing for 5 to 30 minutes, the pre-pressing pressure is 3 to 5 MPa, and the pre-pressing temperature is 110 to 120°C;

[0020] Step 2-2) two-stage formal pressing: the first stage of formal pressing has a pressing time of 5 to 40 minutes, a pressure of 10 to 15 MPa, and a temperature of 130 to 160° C.; the second stage of formal pressing has a pressing time of 10 to 60 minutes, a pressure of 15 to 20 MPa, and a temperature of 170 to 200° C.;

[0021] Step 2-3) Cooling water is passed to cool down to 80-90°C, and the pressure is maintained at 18-20 MPa, and then the mold is removed and placed on a natural horizontal surface, and placed for at least 24 hours before processing.

[0022] The technical solution of the present invention achieves the following beneficial technical effects:

[0023] 1. The flame retardant and heat resistant shielding material of the present invention has an oxygen index of 48, vertical combustion reaches V0 level, and has the characteristics of high strength and low expansion, and also has good neutron and gamma radiation shielding effect, meeting the radiation protection requirements of specific high temperature areas of nuclear reactors.

[0024] 2. The present invention adopts a mixed system of two phenolic resins, combined with a glass fiber reinforcement, which gives the material good mechanical properties while ensuring excellent flame retardant and shielding properties, thereby improving safety and reliability in use.

[0025] 3. The present invention adopts a dry mixing process, and the resin, additives and shielding filler are mixed in one go. The process is simple, which greatly reduces the dust pollution in the production process and ensures the uniformity of the mixing of various materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a ×500 electron microscope image of the flame retardant and heat resistant shielding material prepared in Example 2. DETAILED DESCRIPTION

[0027] Example 1

[0028] The flame retardant and heat resistant shielding material in this embodiment is composed of 6.0 parts by weight of phenolic resin PF2123, 12.0 parts by weight of boron phenolic resin FB5650, 8.0 parts by weight of boron carbide powder with a particle size of 200 mesh, 70.0 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.4wt%, 3.8 parts by weight of glass fiber powder and 0.2 parts by weight of zinc stearate AV300, wherein the glass fiber length in the glass fiber powder is 3.0 mm.

[0029] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0030] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 45r / min, and the mixing time is 60min;

[0031] Step 2) weighing the mixed powder obtained in step 1) and placing it into a preheated mold, pre-pressing for 10 minutes, the pressing temperature is 120° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 10 MPa, the pressing time is 10 minutes, and the pressing temperature is 160° C.; the pressure is increased to 20 MPa, the pressing time is 30 minutes, and the pressing temperature is 190° C.;

[0032] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0033] Example 2

[0034] The flame retardant and heat resistant shielding material in this embodiment is composed of 9.0 parts by weight of phenolic resin PF-301, 9.0 parts by weight of boron phenolic resin PF-241, 0.5 parts by weight of boron carbide powder with a particle size of 325 mesh, 76.4 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.4wt%, 5.0 parts by weight of glass fiber powder and 0.1 parts by weight of calcium stearate CV510, wherein the length of the glass fiber in the glass fiber powder is 0.15mm. The electron microscope image of the flame retardant and heat resistant shielding material prepared in this embodiment is as follows: Figure 1 As shown, the rod-shaped object is glass fiber, the particles with larger particle size are lead powder, the particles with smaller particle size are boron carbide, and the continuous phase is a mixture of phenolic resin PF-301 and boron phenolic resin PF-241.

[0035] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0036] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 45r / min, and the mixing time is 60min;

[0037] Step 2) weighing the mixed powder obtained in step 1) and placing it into a preheated mold, pre-pressing for 10 minutes, the pressing temperature is 120° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 12 MPa, the pressing time is 15 minutes, and the pressing temperature is 160° C.; the pressure is increased to 18 MPa, the pressing time is 40 minutes, and the pressing temperature is 190° C.;

[0038] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0039] Example 3

[0040] The flame retardant and heat resistant shielding material in this embodiment is composed of 3.6 parts by weight of phenolic resin PF-303, 10.0 parts by weight of boron phenolic resin TY-03, 5.0 parts by weight of boron carbide powder with a particle size of 200 mesh, 78.0 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.4wt%, 3.3 parts by weight of glass fiber powder and 0.1 parts by weight of zinc stearate AV302, wherein the glass fiber length in the glass fiber powder is 0.5mm.

[0041] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0042] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 45r / min, and the mixing time is 60min;

[0043] Step 2) weighing the mixed powder obtained in step 1) and placing it into a preheated mold, pre-pressing for 10 minutes, the pressing temperature is 120° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 12 MPa, the pressing time is 15 minutes, and the pressing temperature is 160° C.; the pressure is increased to 18 MPa, the pressing time is 40 minutes, and the pressing temperature is 190° C.;

[0044] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0045] Example 4

[0046] The flame retardant and heat resistant shielding material in this embodiment is composed of 6.5 parts by weight of phenolic resin PF-701, 8.4 parts by weight of boron phenolic resin PF-241, 2.0 parts by weight of boron carbide powder with a particle size of 200 mesh, 81.5 parts by weight of lead powder with a particle size of 200 mesh and a purity greater than or equal to 99.4wt%, 1.5 parts by weight of glass fiber powder and 0.1 parts by weight of calcium stearate CV500W, wherein the glass fiber length in the glass fiber powder is 0.1mm.

[0047] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0048] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 30r / min, and the mixing time is 90min;

[0049] Step 2) weighing the mixed powder obtained in step 1) and placing it into a preheated mold, pre-pressing for 15 minutes, the pressing temperature is 115° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 15 MPa, the pressing time is 30 minutes, and the pressing temperature is 150° C.; the pressure is increased to 20 MPa, the pressing time is 30 minutes, and the pressing temperature is 190° C.;

[0050] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0051] Example 5

[0052] The flame retardant and heat resistant shielding material in this embodiment is composed of 2.7 parts by weight of phenolic resin PF-2123, 10.8 parts by weight of boron phenolic resin FB88, 5.0 parts by weight of boron carbide powder with a particle size of 325 mesh, 80 parts by weight of lead powder with a particle size of 300 mesh and a purity greater than or equal to 99.4wt%, 1.4 parts by weight of glass fiber powder and 0.1 parts by weight of calcium stearate CV502S, wherein the glass fiber length in the glass fiber powder is 2.0 mm.

[0053] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0054] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 45r / min, and the mixing time is 60min;

[0055] Step 2) weighing the mixed powder obtained in step 1) and placing it into a preheated mold, pre-pressing for 10 minutes, the pressing temperature is 120° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 10 MPa, the pressing time is 10 minutes, and the pressing temperature is 150° C.; the pressure is increased to 20 MPa, the pressing time is 30 minutes, and the pressing temperature is 180° C.;

[0056] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0057] Example 6

[0058] The flame retardant and heat resistant shielding material in this embodiment is composed of 3.4 parts by weight of phenolic resin PF-307, 10.0 parts by weight of boron phenolic resin FB89, 0.5 parts by weight of boron carbide powder with a particle size of 325 mesh, 85.0 parts by weight of lead powder with a particle size of 300 mesh and a purity greater than or equal to 99.4wt%, 1.0 parts by weight of glass fiber powder and 0.1 parts by weight of calcium stearate CV550S, wherein the glass fiber length in the glass fiber powder is 0.15mm.

[0059] The flame retardant and heat resistant shielding material in this embodiment is prepared by the following steps:

[0060] Step 1) Mixing: Phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant are weighed and put into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 30r / min, and the mixing time is 90min;

[0061] Step 2) weighing the mixed powder obtained in step 1) and putting it into a mold while hot, pre-pressing for 15 minutes, the pressing temperature is 115° C., and the pressing pressure is 3-5 MPa; the pressure is increased to 15 MPa, the pressing time is 30 minutes, and the pressing temperature is 150° C.; the pressure is increased to 20 MPa, the pressing time is 30 minutes, and the pressing temperature is 190° C.;

[0062] Step 3) Cooling water is passed to cool the product to 80-90°C, and the pressure is maintained at 18-20 MPa during cooling. The product is then removed from the mold and placed on a natural horizontal surface for at least 24 hours before processing.

[0063] The flame retardant and heat resistant shielding materials prepared in Examples 1 to 6 were subjected to performance tests. The test results are shown in Table 1.

[0064] Table 1 Flame retardant and heat resistant shielding material performance test results

[0065] Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 <![CDATA[Density (g / cm 3 )]]> 4.00 4.39 4.55 4.85 5.01 5.50 Tensile strength(MPa) 53.1 48.2 43.5 43.6 38.9 33.4 Bending strength(Mpa) 89.3 78.6 72.2 72.2 81.5 66.2 Oxygen Index LOI 49.1 48.6 48.7 49.7 49.1 49.5 Vertical combustion performance V0 V0 V0 V0 V0 V0 <![CDATA[Coefficient of linear expansion (×10 -6 mm / mm·°C)]]> 26.5 29.5 29.5 27.1 26.2 25.4 Vicat softening point(℃) 260 262 262 265 270 275 <![CDATA[ 252 Cf fast neutron shielding coefficient (4cm)]]> 3.58 3.45 3.43 3.36 3.34 3.23 <![CDATA[ 60 Co photon shielding coefficient (4cm)]]> 2.60 2.84 2.92 3.11 3.21 3.51

[0066] Among them, samples 1 to 6 are samples made from the flame retardant and heat resistant shielding materials prepared in Example 1 to Example 6. From the data recorded in Table 1, it can be seen that the flame retardant and heat resistant shielding material in the present invention has a high oxygen index, reaches the flame retardant level, and the vertical combustion performance reaches V0 level, and the mechanical properties are good.

[0067] In the process of developing the flame retardant and heat resistant shielding material in the present invention, the flame retardant and heat resistant research of the existing shielding materials was carried out with reference to the patent with the announcement number CN103183929B, which is named as a high temperature resistant shielding material with comprehensive neutron and gamma shielding effect. According to the ratio mentioned in the embodiment of the patent - 39 parts of epoxy resin containing 5% boron carbide, 39 parts of lead sand and 3 parts of auxiliary agent - a high temperature resistant shielding material was prepared and subjected to energy testing. The test results are as follows: the density of the high temperature resistant shielding material is 6.06g / cm 3 , Vicat softening point 220℃, oxygen index is only 18. The test results show that the flame retardant performance of the high temperature resistant shielding material is not good enough, and the temperature resistance does not exceed 250℃.

[0068] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A flame retardant and heat resistant shielding material, characterized in that: The invention is composed of the following components: 13-20wt% of phenolic resin composite powder, 0.5-8wt% of boron carbide powder, 70-85wt% of lead powder, 1-5wt% of reinforcing agent and 0.1-0.2wt% of lubricant; wherein the phenolic resin composite powder is a mixture of ordinary phenolic resin and boron phenolic resin.

2. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: In the phenolic resin composite powder, the weight ratio of the common phenolic resin to the boron phenolic resin is 1:1-4.

3. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: The reinforcing agent is glass fiber powder.

4. The flame retardant and heat resistant shielding material according to claim 3, characterized in that: The fiber length in glass fiber powder is 0.1 to 3 mm.

5. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: The lubricant is calcium stearate and / or zinc stearate.

6. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: The density of flame retardant and heat resistant shielding material is 4.0~5.5g / cm 3 .

7. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: The lead powder has a particle size of 300-500 meshes and a purity greater than or equal to 99.4wt%.

8. The flame retardant and heat resistant shielding material according to claim 1, characterized in that: The particle size of the boron carbide powder is less than or equal to 100 μm.

9. The method for preparing the flame-retardant lead-boron modified polyethylene composite material according to claim 1, characterized in that: The steps include: Step 1) mixing: weighing the phenolic resin composite powder, boron carbide powder, lead powder, reinforcing agent and lubricant and putting them into a dry powder mixer for mixing to obtain a mixed powder, the rotation speed is 20 to 60 r / min, and the mixing time is 2 to 120 min; Step 2) Molding: Weigh the mixed powder obtained in step 1) and put it into a mold for pressing to obtain a flame retardant and heat resistant shielding material. The pressing temperature is 170-200°C, the pressing time is 15-100 minutes, and the pressing pressure is 10-20 MPa.

10. The preparation method according to claim 9, characterized in that: In step 2), the specific pressing operation is: Step 2-1) pre-pressing for 5 to 30 minutes, the pre-pressing pressure is 3 to 5 MPa, and the pre-pressing temperature is 110 to 120°C; Step 2-2) two-stage formal pressing: the first stage of formal pressing has a pressing time of 5 to 40 minutes, a pressure of 10 to 15 MPa, and a temperature of 130 to 160° C.; the second stage of formal pressing has a pressing time of 10 to 60 minutes, a pressure of 15 to 20 MPa, and a temperature of 170 to 200° C.; Step 2-3) Cooling water is passed to cool down to 80-90°C, and the pressure is maintained at 18-20 MPa, and then the mold is removed and placed on a natural horizontal surface, and placed for at least 24 hours before processing.

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