A preparation method of aramid filter material suitable for alkaline radiation environment

Abstract

The application belongs to the technical field of filter elements, and particularly relates to a preparation method of aramid filter material suitable for an alkaline radiation environment, which comprises the following steps: S1: adding polyhydric alcohol, p-phenylene diisocyanate and a catalyst into a reaction kettle to obtain a primary prepolymer through reaction; S2: adding a diamine chain extender and a crosslinking agent into the primary prepolymer to obtain a secondary prepolymer through reaction; S3: dispersing and emulsifying deionized water and a curing agent in the secondary prepolymer to obtain a stable polyurethane glue solution; S4: after aramid fibers are carded and separated, the aramid fibers are immersed in the polyurethane glue solution for impregnation treatment, and the aramid fibers after the impregnation treatment are fed into a microwave heating box for curing and forming to obtain aramid filter material. The method can effectively improve the durability and stability of aramid fibers in a high-alkaline and radiation environment by coating a polyurethane coating layer on the surface of the aramid fibers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of filter elements, and particularly relates to a preparation method of aramid filter material suitable for an alkaline radiation environment. BACKGROUND

[0002] In the nuclear energy industry, the treatment of radioactive wastewater is a key link to ensure environmental safety and stable operation. Due to the presence of high-concentration strong alkaline substances such as sodium hydroxide and calcium hydroxide in nuclear wastewater, the pH value of the wastewater is usually higher than 12, which poses a severe chemical corrosion challenge to the filter material. At present, glass fiber filter elements are widely used in nuclear wastewater treatment systems due to their good high-temperature resistance and high mechanical strength. However, long-term exposure to a high-alkaline environment can cause the silicon-oxygen bond (Si-O-Si) in the glass fiber to be attacked by OH- ions, leading to an "alkali dissolution" reaction, material structure damage, strength reduction, and even fiber breakage, thereby affecting the filtration efficiency and system safety.

[0003] To solve this problem, researchers have attempted to introduce aramid fibers as a replacement material. Aramid filter elements have excellent chemical corrosion resistance and thermal stability, and exhibit good resistance to dissolution in a short-term alkaline environment. Studies have shown that the aromatic amide structure on the surface of aramid fibers can effectively resist the erosion of OH- ions and delay the aging process of the material. However, even so, long-term exposure to an extremely high-alkaline environment can still cause partial hydrolysis of the aramid molecular chain, especially in the case where alkalinity and radiation coexist, the fiber structure will gradually deteriorate, and eventually some degree of dissolution and performance degradation will occur. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of aramid filter material suitable for an alkaline radiation environment. This method can more effectively improve the durability and stability of aramid fibers in a high-alkaline and radiation environment, and solve the problem of structural damage and performance degradation of aramid fibers after long-term work in a high-alkaline radiation environment.

[0005] The technical solution to achieve the purpose of the present application is as follows:

[0006] A preparation method of aramid filter material suitable for an alkaline radiation environment, the method comprising:

[0007] S1: adding polyol, p-phenylene diisocyanate, and a catalyst into a reaction kettle to obtain a primary prepolymer;

[0008] S2: adding a diamine chain extender and a crosslinking agent into the primary prepolymer to obtain a secondary prepolymer;

[0009] S3: adding deionized water and a curing agent to the secondary prepolymer for dispersion and emulsification to obtain a stable polyurethane glue solution;

[0010] S4: after the aramid fiber is carded and separated, the aramid fiber is immersed in the polyurethane glue solution for impregnation treatment, the aramid fiber after the impregnation treatment is introduced into a microwave heating box for curing and forming to obtain the aramid filter material.

[0011] Further, the step S1 is specifically: 60-75 parts by mass of polyhydric alcohol is added to a reaction kettle, stirred and heated to 100-120 DEG C, then vacuumized and cooled to 35-40 DEG C, 20-30 parts by mass of p-phenylene diisocyanate and 5-10 parts by mass of a catalyst are added, and polymerization is carried out at 75-90 DEG C for 2-4 hours to obtain a primary prepolymer.

[0012] Further, the polyhydric alcohol is one or both of polyester polyol and polyether polyol, the molecular weight of the polyester polyol is 1000-2000, the molecular weight of the polyether polyol is 2000-4000, the polyester polyol is one or more of polyneopentyl glycol adipate diol, sulfonate polyester diol and polybutylene glycol adipate polyol, and the polyether polyol is polytetramethylene ether glycol.

[0013] Further, the catalyst is one or more of bismuth neodecanoate, bismuth iso-octoate and bismuth laurate.

[0014] Further, the step S2 is specifically: 3-6 parts by mass of a diamine chain extender is added to the primary prepolymer, and incubation is carried out at 70-90 DEG C for 1-3 hours; then cooled to 30-40 DEG C, 1-2 parts by mass of a crosslinking agent is added, and continues to react at 60-70 DEG C for 1-3 hours to obtain a secondary prepolymer.

[0015] Further, the diamine chain extender is 3,3-dichloro-4,4-diaminodiphenyl methane or 3,3-dichlorobenzene diamine.

[0016] Further, the crosslinking agent is trimethylolpropane or pentaerythritol.

[0017] Further, the step S3 is specifically: 300-500 parts by mass of deionized water and 1-5 parts by mass of a curing agent are added to the secondary prepolymer, and dispersion and emulsification are carried out in a high-speed disperser at a speed of 1000-2500 r / min to obtain a stable polyurethane glue solution.

[0018] Further, the curing agent is one or more of diamine-based diphenyl sulfone, diamine-based diphenyl methane and m-phenylenediamine.

[0019] Further, in the step S4, the aramid fiber carding and yarn splitting are specifically: using an opening carding machine to stretch and split yarn at 100 DEG C, humidity 50%, speed 150 m / min, the draw ratio is 2-5 times; the heating temperature of the microwave heating box is 200-250 DEG C, and the time is 2-10 min.

[0020] The beneficial technical effects of the present application are:

[0021] 1. The present application can effectively improve the durability and stability of aramid fiber in high alkaline and radiation environment by coating a layer of polyurethane coating on the surface of aramid fiber. The polyurethane coating not only plays a physical isolation role to prevent alkali from eroding the fiber matrix, but also can absorb part of the radiation energy, thereby delaying the material aging and degradation process.

[0022] 2. The present application selects p-phenylene diisocyanate as one of the raw materials for preparing polyurethane. Since two isocyanate groups are directly connected to the benzene ring, the formed hard segment has a high benzene ring content, which gives the polyurethane higher thermal stability and radiation resistance.

[0023] 3. Compared with the traditional diol chain extender, the diamine chain extender in the present application has a stronger polarity of the urethane group formed in the polyurethane, which is beneficial to enhance the interaction force between the molecular chains. More hydrogen bond network structures can be formed between the hard segments, so that the material has higher cohesive energy density and order in the interior, thereby showing more excellent structural stability and anti-degradation ability when subjected to external stimuli such as radiation or high temperature.

[0024] 4. The present application uses aromatic curing agents such as diamine-based diphenyl sulfone, diamine-based diphenyl methane and m-phenylenediamine, which have a large number of benzene ring structures in the molecular structure, which helps to improve the heat resistance and radiation resistance of the final polyurethane material, and further enhances the protection of the coating on the aramid fiber.

[0025] 5. The present application introduces trimethylolpropane or pentaerythritol as a crosslinking agent to construct a three-dimensional crosslinking network structure, which effectively improves the compactness and mechanical strength of the polyurethane coating, and enhances the structural integrity and durability of the material under complex working conditions.

[0026] 6. The aramid filter material prepared by the present application has excellent alkali resistance, radiation resistance, mechanical properties and thermal stability, and is suitable for use in extreme harsh environments such as nuclear power plants, chemical wastewater treatment, strong alkaline industrial waste gas filtration, etc., and has a broad engineering application prospect. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in conjunction with examples.

[0028] The application provides a preparation method of aramid filter material suitable for an alkaline radiation environment, and specifically comprises the following steps.

[0029] S1: polyols, p-phenylene diisocyanate and a catalyst are added into a reaction kettle for reaction to obtain a primary prepolymer;

[0030] 60-75 parts by mass of polyols are added into a reaction kettle, stirred and heated to 100-120 DEG C, then vacuumized and cooled to 35-40 DEG C, 20-30 parts by mass of p-phenylene diisocyanate and 5-10 parts by mass of a catalyst are added, and polymerization is carried out at 75-90 DEG C for 2-4 hours to obtain a primary prepolymer;

[0031] The polyols are one or both of polyester polyols and polyether polyols, the molecular weight of the polyester polyols is 1000-2000, and the molecular weight of the polyether polyols is 2000-4000.

[0032] The polyester polyols are one or more of polyneopentyl glycol adipate diol, sulfonate polyester diol and polybutylene glycol adipate polyol, and the polyether polyols are polytetramethylene ether glycol.

[0033] The catalyst is an organic bismuth catalyst, and preferably one or more of bismuth neodecanoate, bismuth iso-octoate and bismuth laurate.

[0034] S2: a diamine chain extender and a crosslinking agent are added into the primary prepolymer for reaction to obtain a secondary prepolymer;

[0035] 3-6 parts by mass of a diamine chain extender are added into the primary prepolymer, and reaction is carried out at 70-90 DEG C for 1-3 hours; then the temperature is lowered to 30-40 DEG C, 1-2 parts by mass of a crosslinking agent are added, and reaction is continued at 60-70 DEG C for 1-3 hours to obtain a secondary prepolymer;

[0036] The diamine chain extender is 3,3-dichloro-4,4-diaminodiphenyl methane or 3,3-dichlorobenzene diamine.

[0037] The crosslinking agent is trimethylolpropane or pentaerythritol.

[0038] S3: deionized water and a curing agent are added into the secondary prepolymer for dispersion and emulsification to obtain a stable polyurethane glue solution;

[0039] 300-500 parts by mass of deionized water and 1-5 parts by mass of a curing agent are added into the secondary prepolymer, and dispersion and emulsification are carried out in a high-speed dispersion machine at a rotating speed of 1000-2500 r / min to obtain a stable polyurethane glue solution;

[0040] The curing agent is an aromatic curing agent, and preferably one or more of diamine-based diphenyl sulfone, diamine-based diphenyl methane and m-phenylenediamine.

[0041] S4: After the aramid fiber is carded and separated, it is immersed in the polyurethane glue solution for impregnation treatment, and the aramid fiber after the impregnation treatment is guided into the microwave heating box through the yarn guide under the traction of the yarn winder for curing and forming, so that the aramid filter material with a uniform polyurethane coating on the surface is finally obtained.

[0042] The carding and separation of the aramid fiber specifically includes: using an opening carding machine to stretch and separate at 100 DEG C, 50% humidity and a speed of 150 m / min, the draw ratio is 2-5 times, and if necessary, the humidity is increased to prevent static accumulation, so that the fiber is uniformly distributed and the strip consistency is stable.

[0043] The heating temperature of the microwave heating box is 200-250 DEG C, and the time is 2-10 min, preferably 5 min.

[0044] The application also provides an aramid filter material suitable for an alkaline radiation environment, which is prepared by the above preparation method.

[0045] Example 1

[0046] The application provides a preparation method of an aramid filter material suitable for an alkaline radiation environment, which specifically includes the following steps:

[0047] S1: 20 parts by mass of polyneopentylene adipate diol, 40 parts by mass of polytetramethylene ether glycol are added to a reaction kettle, stirred and heated to 100 DEG C, then vacuumized and cooled to 40 DEG C, 20 parts by mass of p-phenylene diisocyanate and 5 parts by mass of bismuth laurate are added, and a polymerization reaction is carried out at 90 DEG C for 2 h to obtain a primary prepolymer.

[0048] S2: 4 parts by mass of 3,3-dichloro-4,4-diamino diphenyl methane is added to the primary prepolymer, and a reaction is carried out at 70 DEG C for 2 h; then the temperature is lowered to 40 DEG C, 1 part by mass of trimethylolpropane is added, and a reaction is carried out at 70 DEG C for 2 h to obtain a secondary prepolymer.

[0049] S3: 500 parts by mass of deionized water and 3 parts by mass of diamino diphenyl sulfone are added to the secondary prepolymer, and a dispersion emulsification is carried out in a high-speed dispersion machine at a speed of 2500 r / min to obtain a stable polyurethane glue solution.

[0050] S4: After the aramid fiber is carded and separated, it is immersed in the polyurethane glue solution for impregnation treatment; then it is guided into the microwave heating box through the yarn guide under the traction of the yarn winder for curing and forming, the heating temperature is 200 DEG C, and the heating time is 5 min, so that the aramid filter material with a uniform polyurethane coating on the surface is finally obtained.

[0051] The aramid filter material prepared in this example was tested for performance, and the results are as follows:

[0052] After soaking in a NaOH solution with pH 12 for 30 days, the tensile strength retention rate was 86%, and after being subjected to 1 MGy of γ-ray irradiation, the strength retention rate was 81%, and the thermal decomposition temperature was 371℃.

[0053] Example 2

[0054] In this example, the following parameters are different from those in Example 1, and the other parameters and preparation methods are the same as those in Example 1.

[0055] Polytetramethylene ether glycol 60 parts by mass;

[0056] P-phenylene diisocyanate 20 parts by mass;

[0057] Bismuth neodecanoate 5 parts by mass;

[0058] Diamine chain extender (3,3-dichloro-4,4-diaminodiphenyl methane) 3 parts by mass;

[0059] Pentaerythritol 1 part by mass;

[0060] Deionized water 300 parts by mass;

[0061] Diaminodiphenyl methane 1 part by mass.

[0062] In step S4, the microwave curing parameters are: heating temperature is 200℃, and heating time is 2 min.

[0063] The aramid filter material prepared in this example was tested for performance, and the results are as follows:

[0064] After soaking in a NaOH solution with pH 12 for 30 days, the tensile strength retention rate was 80%, and after being subjected to 1 MGy of γ-ray irradiation, the strength retention rate was 75%, and the thermal decomposition temperature was 365℃.

[0065] Example 3

[0066] In this example, the following parameters are different from those in Example 1, and the other parameters and preparation methods are the same as those in Example 1.

[0067] Polytetramethylene ether glycol 75 parts by mass;

[0068] P-phenylene diisocyanate 30 parts by mass;

[0069] Bismuth isooctoate 10 parts by mass;

[0070] Diamine chain extender (3,3-dichloro-4,4-diaminodiphenyl methane) 6 parts by mass;

[0071] Trimethylolpropane 2 parts by mass;

[0072] 500 parts by mass of deionized water;

[0073] 5 parts by mass of m-phenylenediamine.

[0074] In step S4, the microwave curing parameters are as follows: heating temperature is 250℃, and heating time is 10 min.

[0075] The aramid filter material prepared in the example is subjected to performance test, and the results are as follows:

[0076] After being soaked in NaOH solution with pH 12 for 30 days, the tensile strength retention rate is 90%, and after being subjected to 1 MGy gamma ray irradiation, the strength retention rate is 85%. The thermal decomposition temperature is 385℃.

[0077] The application has been described in detail in combination with the examples above, but the application is not limited to the above examples, and various changes can be made within the knowledge possessed by those skilled in the art without departing from the gist of the application. The contents not described in detail in the application can adopt the prior art.

Claims

1. A method for preparing aramid filtration material suitable for use in an alkaline radiation environment, characterized by, The method comprises: S1: adding polyhydric alcohol, p-phenylene diisocyanate and a catalyst into a reaction kettle to perform a reaction to obtain a primary prepolymer; S2: adding a diamine chain extender and a crosslinking agent into the primary prepolymer to perform a reaction to obtain a secondary prepolymer; wherein the diamine chain extender is 3,3-dichloro-4,4-diamino diphenyl methane or 3,3-dichloro diphenyl diamine, and the crosslinking agent is trimethylolpropane or pentaerythritol; S3: adding deionized water and a curing agent into the secondary prepolymer to perform dispersion emulsification to obtain a stable polyurethane glue solution; wherein the curing agent is one or more of diamine diphenyl sulfone, diamine diphenyl methane and m-phenylenediamine; S4: after the aramid fiber is carded and separated, the aramid fiber is immersed in the polyurethane glue solution to perform impregnation treatment, the aramid fiber after the impregnation treatment is put into a microwave heating box to perform curing and forming to obtain an aramid filter material.

2. The method of claim 1, wherein the aramid filtration material is prepared for use in an alkaline radiation environment. The step S1 specifically comprises: adding 60-75 parts by mass of polyhydric alcohol into a reaction kettle, stirring and heating to 100-120 DEG C, then vacuumizing and cooling to 35-40 DEG C, adding 20-30 parts by mass of p-phenylene diisocyanate and 5-10 parts by mass of a catalyst, and performing polymerization reaction at 75-90 DEG C for 2-4 hours to obtain a primary prepolymer.

3. The method for preparing an aramid filter material suitable for alkaline radiation environment according to claim 1, characterized in that, The polyhydric alcohol is one or both of polyester polyol and polyether polyol, the molecular weight of the polyester polyol is 1000-2000, the molecular weight of the polyether polyol is 2000-4000, the polyester polyol is one or more of polyneopentyl glycol adipate diol, sulfonate polyester diol and polybutylene glycol adipate polyol, and the polyether polyol is polytetramethylene ether glycol.

4. The method of claim 1, wherein the aramid filtration material is prepared for use in an alkaline radiation environment. The catalyst is one or more of bismuth neodecanoate, bismuth iso-octoate and bismuth laurate.

5. The method of claim 1, wherein the aramid filtration material is prepared for use in an alkaline radiation environment. The step S2 specifically comprises: adding 3-6 parts by mass of a diamine chain extender into the primary prepolymer, and performing heat preservation reaction at 70-90 DEG C for 1-3 hours; then cooling to 30-40 DEG C, adding 1-2 parts by mass of a crosslinking agent, and continuing to perform reaction at 60-70 DEG C for 1-3 hours to obtain a secondary prepolymer.

6. The method of claim 1, wherein the aramid filtration material is prepared for use in an alkaline radiation environment. The step S3 specifically comprises: adding 300-500 parts by mass of deionized water and 1-5 parts by mass of a curing agent into the secondary prepolymer, and performing dispersion emulsification in a high-speed dispersion machine at a rotating speed of 1000-2500 r / min to obtain a stable polyurethane glue solution.

7. The method of claim 1, wherein the aramid filtration material is prepared for use in an alkaline radiation environment. In the step S4, the carding and separation of the aramid fiber specifically comprises: using an opening carding machine to perform drawing and separation at a speed of 150 m / min, a temperature of 100 DEG C and a humidity of 50%, and the drawing multiple is 2-5 times; the heating temperature of the microwave heating box is 200-250 DEG C, and the time is 2-10 min.