A high-strength environmental protection epoxy resin joint sealant and its preparation method

Abstract

The present invention belongs to the field of epoxy resin joint adhesives, and discloses a high-strength and environmentally friendly epoxy resin joint adhesive and a preparation method thereof. The joint adhesive comprises component A and component B; component A comprises the following components: an epoxy resin mixture, fly ash hollow glass microspheres, a first filler, a first diluent, and optionally a first auxiliary agent; component B comprises the following components: a modified amine curing agent, fly ash hollow glass microspheres, and a second filler, and at least one of an optionally second diluent, an accelerator, and a second auxiliary agent. The epoxy resin joint adhesive of the present invention that does not seep oil and is resistant to yellowing has significantly improved performance such as odor grade, sag, tensile shear strength, bonding strength, and T-impact peel length compared to ordinary products.

Description

Technical Field

[0001] The present invention belongs to the field of epoxy resin joint adhesives, and more specifically, relates to a high-strength and environmentally friendly epoxy resin joint adhesive and a preparation method thereof. Background Art

[0002] Materials such as gypsum and concrete are widely used in indoor and outdoor decoration due to their excellent usability. Due to the particularity of their usage locations, it is common for there to be gaps at the joints of these materials, as well as around door frames, building facades, new and old walls, internal and external corners, and roof cracks. Therefore, it is necessary to seal the joints to meet the usage requirements of the building and the aesthetic needs. Traditional joint sealing materials generally include materials such as polyurethane, silicone, and acrylic. However, these traditional joint sealing materials generally have problems such as shrinkage 、 severe odor, aging and cracking at the joints, which seriously affect people's physical health and the aesthetic effect of indoor and outdoor decoration.

[0003] In recent years, with the continuous development of epoxy resin adhesives, epoxy joint adhesives that play a role in filling gaps have been widely used in the process of indoor and outdoor decoration. The mandatory national building material standard GB / T 36797-2018 "Epoxy Resin Joint Adhesive for Preventing Cracking in Decoration" stipulates the performance requirements of epoxy resin joint adhesives. Epoxy resin joint adhesive products on the market are generally cured under normal temperature conditions and consist of two components, A and B. However, the levels of relevant production and research enterprises in the industry vary widely, and there is generally a phenomenon of using inferior materials instead of good ones. The phenomenon of oil leakage of the materials during storage is serious, which seriously affects the performance during use, causing secondary cracking at the wall joints and posing a serious threat to people's life and property safety. Moreover, the existing two components A and B have a strong odor and a high volatile content, which will harm people's physical health for a long time. And the glue sample is prone to yellowing, which will seriously contaminate the adhered materials in the long run.

[0004] Therefore, there is an urgent need to propose a new high-strength and environmentally friendly epoxy resin joint adhesive and a preparation method thereof. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the prior art and propose a high-strength and environmentally friendly epoxy resin joint adhesive and a preparation method thereof. The non-oil-leaking and yellowing-resistant epoxy resin joint adhesive of the present invention has significantly improved performance in terms of odor grade, sag, tensile shear strength, bonding strength, and T-impact peel length compared to ordinary products.

[0006] To achieve the above object, on the one hand, the present invention provides a high-strength and environmentally friendly epoxy resin joint adhesive, which includes component A and component B;

[0007] Component A includes the following components: epoxy resin mixture, fly ash hollow glass microspheres, first filler, first diluent, and optionally first auxiliary agent;

[0008] The component B includes the following components: a modified amine curing agent, fly ash hollow glass microspheres, and a second filler, and optionally at least one of a second diluent, an accelerator, and a second auxiliary agent.

[0009] According to the present invention, preferably,

[0010] The component A includes the following components in parts by weight: 20 - 30 parts of an epoxy resin mixture, 5 - 25 parts of fly ash hollow glass microspheres, 40 - 80 parts of a first filler, 5 - 10 parts of a first diluent, and 0 - 3 parts of a first auxiliary agent;

[0011] The component B includes the following components in parts by weight: 20 - 40 parts of a modified amine curing agent, 5 - 25 parts of fly ash hollow glass microspheres, 40 - 70 parts of a second filler, 0 - 10 parts of a second diluent, 0 - 3 parts of an accelerator, and 0 - 3 parts of a second auxiliary agent.

[0012] According to the present invention, preferably,

[0013] The component A includes the following components in parts by weight: 20 - 30 parts of an epoxy resin mixture, 10 - 20 parts of fly ash hollow glass microspheres, 50 - 70 parts of a first filler, 5 - 10 parts of a first diluent, and 0 - 3 parts of a first auxiliary agent;

[0014] The component B includes the following components in parts by weight: 20 - 30 parts of a modified amine curing agent, 10 - 20 parts of fly ash hollow glass microspheres, 40 - 60 parts of a second filler, 0 - 10 parts of a second diluent, 0 - 3 parts of an accelerator, and 0 - 3 parts of a second auxiliary agent.

[0015] According to the present invention, preferably, the epoxy resin mixture is prepared by compounding and mixing diaminodiphenylmethane tetraglycidylamine, bis((3,4 - epoxycyclohexyl)methyl)adipate, and bisphenol A type epoxy resin; preferably, the dosage ratio of diaminodiphenylmethane tetraglycidylamine, bis((3,4 - epoxycyclohexyl)methyl)adipate, and bisphenol A type epoxy resin is (4 - 7):(6 - 9):(10 - 14).

[0016] According to the present invention, preferably, the modified amine curing agent is prepared by graft modification of diaminodiphenylmethane tetraglycidylamine and bis((3,4 - epoxycyclohexyl)methyl)adipate as matrix materials, successively through a non - active diluent, a small molecule amine, and an active diluent.

[0017] According to the present invention, preferably, the non - active diluent is at least one of benzyl alcohol, dioctyl phthalate, and dibutyl phthalate.

[0018] According to the present invention, preferably, the small molecule amine is methylcyclohexanediamine and / or polyetheramine.

[0019] According to the present invention, preferably, the active diluent is at least one of C12-14 alkyl glycidyl ether, 1,4-butanediol diglycidyl ether, propylene oxide propyl ether, and propylene glycol diglycidyl ether.

[0020] According to the present invention, preferably, the preparation method of the modified amine curing agent includes:

[0021] (1) Uniformly mix the diaminodiphenylmethane tetraglycidylamine and bis((3,4-epoxycyclohexyl)methyl)adipate with the non-active diluent to obtain a mixture;

[0022] (2) Mix the mixture with the small molecule amine and the active diluent and carry out graft modification to obtain the modified amine curing agent.

[0023] According to the present invention, preferably, the temperature for carrying out the graft modification is 50-70 °C and the time is 1-5 h.

[0024] According to the present invention, preferably, the dosage ratio of the diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl)adipate, non-active diluent, small molecule amine, and active diluent is (7-9):(10-15):(15-25):(35-45):(15-25).

[0025] In the present invention, as a preferred embodiment, in the preparation method of the modified amine curing agent, the mixture is first mixed with the small molecule amine and subjected to graft modification for 1.5-2 h at a temperature of 50-70 °C; then the active diluent is added and mixed and subjected to graft modification for 1-2 h at a temperature of 50-70 °C to obtain the modified amine curing agent.

[0026] According to the present invention, preferably, the particle size of the fly ash hollow glass microspheres is less than 32 μm.

[0027] According to the present invention, preferably, the first filler and the second filler are each independently at least one of heavy calcium, active calcium, nano calcium, barium sulfate, modified barium sulfate, quartz powder, talc powder, and bentonite.

[0028] According to the present invention, preferably, the first diluent and the second diluent are each independently at least one of propylene carbonate, 1,4-butanediol diglycidyl ether, phenyl glycidyl ether, benzyl alcohol, polypropylene glycol diglycidyl ether, and C12-14 fatty glycidyl ether.

[0029] According to the present invention, preferably, the first auxiliary agent and the second auxiliary agent are each independently at least one of an antifoaming agent, a dispersant, and a toughening agent.

[0030] On the other hand, the present invention provides a method for preparing the high-strength and environmentally friendly epoxy resin joint sealant, comprising the following steps:

[0031] S1: Mix and stir evenly the epoxy resin mixture, fly ash hollow glass microspheres, the first filler, the first diluent, and optionally the first auxiliary agent, stir under vacuum, and cool and can to obtain the component A;

[0032] S2: Mix and stir evenly the modified amine curing agent, fly ash hollow glass microspheres, the second filler, and optionally the second diluent, a promoter, and the second auxiliary agent, stir under vacuum, and cool and can to obtain the component B.

[0033] According to the present invention, preferably, in step S1, the mixing and stirring time is 5 - 60 min, and the rate is 50 - 300 RPM. The vacuum stirring time is 20 - 30 min, and the rate is 15 - 25 RPM.

[0034] According to the present invention, preferably, in step S2, the mixing and stirring time is 5 - 60 min, and the rate is 50 - 300 RPM. The vacuum stirring time is 20 - 30 min, and the rate is 15 - 25 RPM.

[0035] In the present invention, as a preferred embodiment, the method for preparing the high-strength and environmentally friendly epoxy resin joint sealant comprises the following steps:

[0036] Mix and stir the epoxy resin mixture, the first diluent, and the first auxiliary agent at 50 - 100 RPM for 5 - 10 min, add fly ash hollow glass microspheres and stir at 150 - 300 RPM for 15 - 20 min, add the first filler and stir at 100 - 300 RPM for 20 - 30 min, stir under vacuum at 20 RPM for 30 min, cool and can to obtain the component A;

[0037] Mix and stir the modified amine curing agent, the second diluent, the promoter, and the second auxiliary agent at 50 RPM for 5 - 10 min, add fly ash hollow glass microspheres and stir at 150 - 300 RPM for 15 - 20 min, add the second filler and stir at 100 - 300 RPM for 20 - 30 min, stir under vacuum at 20 RPM for 30 min, cool and can to obtain the component B.

[0038] The beneficial effects of the technical solution of the present invention are as follows:

[0039] The epoxy resin mixture of the present invention is prepared by compounding and mixing diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl) adipate and bisphenol A epoxy resin, which endows the joint sealant with extremely high mechanical strength and excellent yellowing resistance and aging resistance.

[0040] Synthesis of the modified amine curing agent of the present invention: (1) It can effectively reduce the volatilization of small molecule amines and endow the material with excellent environmental protection performance; (2) Greatly shorten the curing time of the reaction; (3) The reactive diluent and the non-reactive diluent are used in combination. While ensuring the reaction activity of the joint sealant, it endows the material with higher impact strength.

[0041] In the present invention, fly ash hollow glass microspheres are introduced. On the one hand, the fly ash hollow glass microspheres have a stress concentration effect, which is easy to cause micro-cracking of the surrounding epoxy resin and absorb a certain amount of deformation work. The presence of the fly ash hollow glass microspheres hinders the crack propagation of the epoxy resin. The hollow structure of the hollow glass microspheres increases its specific surface area and the contact area with the epoxy resin, and more micro-cracks are generated when impacted, so as to absorb more deformation work, endowing the material with better impact resistance and playing a role in strengthening and toughening. On the other hand, taking advantage of the low density of the hollow structure of the hollow glass microspheres (generally, the density of inorganic fillers is greater than that of epoxy resin), the phenomenon of epoxy resin precipitation during storage can be effectively solved. On the third hand, fly ash, as a waste generated from power plant coal combustion, will cause serious pollution of the land, blockage of river channels and endanger people's health. The present invention perfectly interprets the concept of "turning waste into protection".

[0042] Other features and advantages of the present invention will be described in detail in the following specific implementation part. Brief Description of the Drawings

[0043] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above-mentioned and other objects, features and advantages of the present invention will become more obvious. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0044] Figure 1 Shows the yellowing phenomenon of the epoxy resin joint sealants of Examples 1-3 and Comparative Examples 1-3 of the present invention after being placed in an 80 °C oven for 7 days of thermal storage.

[0045] Figure 2 Shows the oil leakage phenomenon of the A component of the epoxy resin joint sealants of Examples 1-3 and Comparative Examples 1-3 of the present invention after being placed in a 60 °C oven for 7 days of thermal storage.

[0046] Figure 3The oil seepage phenomenon of the B component of the epoxy resin joint adhesive in Examples 1-3 and Comparative Examples 1-3 of the present invention is shown after being placed in an oven at 60 °C and thermally stored for 7 days. Detailed Description of the Invention

[0047] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0048] In the following respective examples and comparative examples:

[0049] The epoxy resin mixture is prepared by compounding and mixing diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl)adipate and bisphenol A epoxy resin; the dosage ratio of diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl)adipate and bisphenol A epoxy resin is 5:7:12.

[0050] The first filler of component A is heavy calcium and active calcium, and the ratio is 2:1;

[0051] The first diluent of component A is C12-14 fatty glycidyl ether;

[0052] The defoaming agent of component A is purchased from Anjikang, and the model is 5630A;

[0053] The dispersant of component A is purchased from Anjikang, and the model is 6110;

[0054] The toughening agent of component A is purchased from Anjikang, and the model is 4610A;

[0055] The preparation method of the modified amine curing agent includes:

[0056] (1) Uniformly mix the diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl)adipate and benzyl alcohol to obtain a mixture;

[0057] (2) First graft-modify the mixture with methylcyclohexanediamine and polyetheramine for 1.5-2 h at a temperature of 50-70 °C; then add C12-14 alkyl glycidyl ether and mix and graft-modify for 1-2 h at a temperature of 50-70 °C to obtain the modified amine curing agent.

[0058] The dosage ratio of the diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl)adipate, benzyl alcohol, methylcyclohexanediamine, polyetheramine, and C12-14 alkyl glycidyl ether is 8:12:20:15:25:20;

[0059] The second filler of component B is heavy calcium and activated calcium, and the ratio is 2:1;

[0060] The second diluent of component B is benzyl alcohol;

[0061] The defoamer of component B is selected from Anjikang, and the model is 5610A;

[0062] The dispersant of component B is selected from Anjiakang, and the model is 6110;

[0063] The toughening agent of component B is selected from Anjikang, and the model is 4610;

[0064] The accelerator of component B is selected from Air Products Chemicals, and the model is K54.

[0065] Example 1

[0066] This example provides a high-strength and environmentally friendly epoxy resin joint sealant. The joint sealant includes component A and component B, as shown in Table 1:

[0067] Component A includes the following components in parts by weight: 25 parts of epoxy resin mixture, 20 parts of fly ash hollow glass microspheres, 55 parts of the first filler, 7 parts of the first diluent, 1 part of defoamer, 1 part of toughening agent, and 1 part of dispersant;

[0068] Component B includes the following components in parts by weight: 25 parts of modified amine curing agent, 20 parts of fly ash hollow glass microspheres, 45 parts of the second filler, 5 parts of the second diluent, 2 parts of accelerator, 1 part of defoamer, 1 part of toughening agent, and 1 part of dispersant.

[0069] The preparation method of the high-strength and environmentally friendly epoxy resin joint sealant includes the following steps:

[0070] Mix and stir the epoxy resin mixture, the first diluent, and the first additives at 50 RPM for 10 minutes, add fly ash hollow glass microspheres and mix and stir at 150 RPM for 20 minutes, add the first filler and mix and stir at 100 RPM for 15 minutes, and finally stir at 20 RPM under vacuum for 30 minutes, then cool and can to obtain component A;

[0071] Mix the modified amine curing agent, the second diluent, the accelerator and the second auxiliary agent and stir at 50 RPM for 10 minutes. Add fly ash hollow glass microspheres and stir at 150 RPM for 20 minutes. Then add the second filler and stir at 100 RPM for 15 minutes. Finally, stir at 20 RPM under vacuum for 30 minutes, cool and can to obtain the Component B.

[0072] Example 2-3

[0073] Examples 2-3 respectively provide a high-strength and environmentally friendly epoxy resin joint sealant. The differences between Examples 2-3 and Example 1 are only in the specific components, as shown in Table 1.

[0074] Comparative Examples 1-2

[0075] Comparative Examples 1-2 respectively provide an epoxy resin joint sealant. The differences between Comparative Examples 1-2 and Example 1 are only in the specific components, as shown in Table 1.

[0076] Comparative Example 3

[0077] The epoxy resin joint sealant provided in this comparative example is a commercially available epoxy resin joint sealant, with the manufacturer being Artisan Family and the model being Craftsman Product.

[0078] Table 1

[0079]

[0080] Test Example 1

[0081] Test the epoxy resin joint sealants of the above examples and comparative examples according to the standard of GB / T 36797-2018 "Epoxy Resin Joint Sealant for Preventing Cracking in Decoration". The test results are shown in Table 2. It can be seen from the test results that after introducing the modified amine curing agent and fly ash hollow glass microspheres, the odor level, sag, tensile shear strength, bonding strength and T-impact peel length of the epoxy resin joint sealant can be significantly improved.

[0082] Table 2

[0083]

[0084] Test Example 2

[0085] Place the products obtained by mixing the epoxy resin joint sealants of the above examples and comparative examples evenly at room temperature, and observe the complete curing time of the products, as shown in Table 3. The performance of the modified amine curing agent synthesized and prepared in the present invention has a significantly better curing effect on the products than that of the polyamide amine curing agent and the externally purchased dry-hanging glue product of Comparative Example 3.

[0086] Table 3

[0087] Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Fully cured, min 150 130 123 124 180 280

[0088] Test Example 3

[0089] The product obtained by uniformly mixing the epoxy resin joint adhesives of the above-mentioned examples and comparative examples was placed in an oven at 80 °C and heat stored for 7 days, and then the yellowing phenomenon of the product was observed. As Figure 1 shown, for the epoxy resin joint adhesive of the present invention, after heat storage for 7 days, the product basically did not show yellowing. For the joint adhesive product prepared with the polyamide curing agent of Comparative Example 2 and the commercially available joint adhesive product of Comparative Example 3, obvious yellowing occurred.

[0090] Test Example 4

[0091] The A and B components of the epoxy resin joint adhesives of the above-mentioned examples and comparative examples were respectively placed in an oven at 60 °C and heat stored for 7 days, and then the oil leakage phenomenon of the product was observed. As Figure 2 、 3 shown, for the A component product of the present invention after adding fly ash hollow glass microspheres, after heat storage for 7 days, there was no resin precipitation phenomenon in the A component of the product; for the B component product of the present invention, after heat storage for 7 days, there was basically no oil leakage phenomenon in the B component of the product. For the B component of the dry hanging adhesive product prepared with the polyamide curing agent of Comparative Example 2 and the B component of the commercially available dry joint adhesive product of Comparative Example 3, obvious oil leakage occurred.

[0092] The various embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A high-strength and environmentally friendly epoxy resin joint sealant, characterized in that, The joint sealant comprises component A and component B; Component A comprises the following components: an epoxy resin mixture, fly ash hollow glass microspheres, a first filler, a first diluent, and optionally a first auxiliary agent; The epoxy resin mixture is prepared by compounding and mixing diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl) adipate and bisphenol A-type epoxy resin; the dosage ratio of diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl) adipate and bisphenol A-type epoxy resin is (4-7):(6-9):(10-14); Component B comprises the following components: a modified amine curing agent, fly ash hollow glass microspheres, a second filler, and at least one of an optionally second diluent, a promoter and a second auxiliary agent; The modified amine curing agent is prepared by graft modification of diaminodiphenylmethane tetraglycidylamine and bis((3,4-epoxycyclohexyl)methyl) adipate as matrix materials in sequence through a non-active diluent, a small molecule amine and an active diluent; The non-active diluent is at least one of benzyl alcohol, dioctyl phthalate and dibutyl phthalate; The small molecule amine is methylcyclohexanediamine and / or polyetheramine; The active diluent is at least one of C12-14 alkyl glycidyl ether, propylene oxide propyl ether and propylene glycol diglycidyl ether; The dosage ratio of diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl) adipate, non-active diluent, small molecule amine and active diluent is (7-9):(10-15):(15-25):(35-45):(15-25).

2. The high-strength and environmentally friendly epoxy resin joint sealant according to claim 1, wherein, Component A comprises the following components in parts by weight: 20-30 parts of epoxy resin mixture, 5-25 parts of fly ash hollow glass microspheres, 40-80 parts of first filler, 5-10 parts of first diluent and 0-3 parts of first auxiliary agent; Component B comprises the following components in parts by weight: 20-40 parts of modified amine curing agent, 5-25 parts of fly ash hollow glass microspheres, 40-70 parts of second filler, 0-10 parts of second diluent, 0-3 parts of promoter and 0-3 parts of second auxiliary agent.

3. The high-strength and environmentally friendly epoxy resin joint sealant according to claim 2, wherein, Component A comprises the following components in parts by weight: 20-30 parts of epoxy resin mixture, 10-20 parts of fly ash hollow glass microspheres, 50-70 parts of first filler, 5-10 parts of first diluent and 0-3 parts of first auxiliary agent; Component B comprises the following components in parts by weight: 20-30 parts of modified amine curing agent, 10-20 parts of fly ash hollow glass microspheres, 40-60 parts of second filler, 0-10 parts of second diluent, 0-3 parts of promoter and 0-3 parts of second auxiliary agent.

4. The high-strength and environmentally friendly epoxy resin joint sealant according to claim 1, wherein, The preparation method of the modified amine curing agent comprises: (1) Uniformly mixing the diaminodiphenylmethane tetraglycidylamine, bis((3,4-epoxycyclohexyl)methyl) adipate and the non-active diluent to obtain a mixture; (2) Mixing the mixture with the small molecule amine and the active diluent and carrying out graft modification to obtain the modified amine curing agent.

5. The high-strength and environmentally friendly epoxy resin joint sealant according to claim 4, wherein, The temperature for carrying out the graft modification is 50 - 70 °C, and the time is 1 - 5 h.

6. The high-strength and environmentally friendly epoxy resin joint sealant according to any one of claims 1-3, wherein, The particle size of the fly ash hollow glass microspheres is less than 32 μm; The first filler and the second filler are each independently at least one of heavy calcium carbonate, active calcium carbonate, nano calcium carbonate, barium sulfate, modified barium sulfate, quartz powder, talc powder, and bentonite; The first diluent and the second diluent are each independently at least one of propylene carbonate, 1,4 - butanediol diglycidyl ether, phenyl glycidyl ether, benzyl alcohol, polypropylene glycol diglycidyl ether, and C12 - 14 fatty glycidyl ether; The first additive and the second additive are each independently at least one of an antifoaming agent, a dispersant, and a toughening agent.

7. A preparation method of the high-strength and environmentally friendly epoxy resin joint sealant according to any one of claims 1-6, characterized in that, It includes the following steps: S1: Mix and stir evenly the epoxy resin mixture, fly ash hollow glass microspheres, the first filler, the first diluent, and optionally the first additive, stir under vacuum, cool and fill into cans to obtain the component A; S2: Mix and stir evenly the modified amine curing agent, fly ash hollow glass microspheres, the second filler, and optionally the second diluent, accelerator, and the second additive, stir under vacuum, cool and fill into cans to obtain the component B.

8. The preparation method of the high-strength and environmentally friendly epoxy resin joint sealant according to claim 7, wherein, In step S1: The mixing and stirring time is 5 - 60 min, and the rate is 50 - 300 RPM; The vacuum stirring time is 20 - 30 min, and the rate is 15 - 25 RPM; In step S2: The mixing and stirring time is 5 - 60 min, and the rate is 50 - 300 RPM; The vacuum stirring time is 20 - 30 min, and the rate is 15 - 25 RPM.

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