High-strength and high-toughness modified plastic particles, and preparation method and application thereof

Abstract

The application relates to the technical field of high polymer materials, in particular to a modified plastic particle with high strength and high toughness as well as a preparation method and application thereof. The preparation method of the modified plastic particle with high strength and high toughness comprises the following steps: MMT / CNTs is reacted with diisocyanate to prepare isocyanate-based MMT / CNTs; the isocyanate-based MMT / CNTs is reacted with glycerol 1,3-diglycerol diacrylate to prepare MMT / CNTs containing alkenyl groups; maleic anhydride, the MMT / CNTs containing alkenyl groups and POE are subjected to grafting reaction to prepare a modifier; the modifier, an additive and PA6 are melt blended, extruded, cooled, and granulated to obtain the modified plastic particle with high strength and high toughness. Since the nano filler MMT / CNTs and the polyolefin elastomer POE are introduced, the modified plastic particle with PA6 as a matrix has high strength and high toughness.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a high-strength, high-toughness modified plastic particle, its preparation method, and its application. Background Technology

[0002] PA6 (polyamide 6) is widely used in many sectors of the national economy due to its high mechanical strength, excellent heat resistance, abrasion resistance, and oil resistance. However, its poor impact resistance limits its application, thus necessitating toughening modification of PA6. The common method for toughening PA6 is to add flexible toughening polymers, such as POE (ethylene-octene copolymer).

[0003] Chinese patent CN103131168B discloses a permanent antistatic PA6 / POE alloy and its preparation method. The raw materials include antistatic masterbatch, PA6, POE, and a compatibilizer. The resulting alloy material exhibits good antistatic properties and high overall mechanical properties. However, the polarity difference between the polar PA6 and the non-polar polyolefin elastomer POE leads to poor compatibility and severe phase separation during blending, resulting in decreased impact strength. Furthermore, the introduction of flexible toughening polymers reduces the tensile strength of the rigid polymer PA6, meaning that PA6-based plastic materials struggle to possess both high strength and high toughness. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-strength and high-toughness modified plastic particle, its preparation method, and its application, thereby solving the problem that PA6-based modified plastic particles in the prior art cannot simultaneously possess both high strength and high toughness.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing high-strength and high-toughness modified plastic particles includes the following steps:

[0007] Step 1: Add MMT / CNTs (montmorillonite / carbon nanotubes) to toluene, stir to disperse, add diisocyanate and catalyst, react, centrifuge, wash, and dry to obtain isocyanate-based MMT / CNTs;

[0008] Step 2: Add glycerol 1,3-diglycerol glycol diacrylate to toluene, stir and disperse, then add isocyanate-based MMT / CNTs and catalyst, and react. After the reaction is complete, centrifuge, wash, and dry to obtain alkenyl-containing MMT / CNTs.

[0009] Step 3: Dissolve maleic anhydride and initiator in acetone, add alkenyl-containing MMT / CNTs, stir and disperse to obtain a mixture;

[0010] The mixture is added to POE, mixed, extruded through a twin-screw extruder, cooled, and pelletized to obtain the modifier;

[0011] Step 4: Melt-blend the modifier and additives with PA6, extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0012] Preferably, in step one, the mass ratio of MMT / CNTs, diisocyanate, catalyst and toluene is 100:(50-70):(0.05-0.1):(400-600), and the reaction conditions are under nitrogen protection and at a temperature of 75-85°C for 60-100 min.

[0013] Preferably, the diisocyanate comprises toluene-2,4-diisocyanate, and the catalyst comprises stannous octoate.

[0014] Preferably, the MMT / CNTs in step one are prepared by the following steps:

[0015] S1. N,N'-diisopropylcarbodiimide (DIC), 1-hydroxybenzotriazole (HOBT), and carboxylated multi-walled carbon nanotubes were added to N,N-dimethylformamide and ultrasonically dispersed to obtain a carbon nanotube dispersion. Triethylenetetramine was added to the carbon nanotube dispersion and reacted. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes.

[0016] S2. Modified carbon nanotubes were added to deionized water, ultrasonically dispersed, and hydrochloric acid was added dropwise under stirring. The reaction was stirred to obtain a carbon nanotube ammonium salt dispersion.

[0017] Montmorillonite (MMT) was added to deionized water and ultrasonically dispersed. Then, a carbon nanotube ammonium salt dispersion was added and the mixture was reacted. After the reaction was completed, the mixture was filtered, washed, and dried to obtain MMT / CNTs.

[0018] Preferably, in S1, the mass ratio of N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole, carboxylated multi-walled carbon nanotubes, N,N-dimethylformamide, and triethylenetetramine is (0.01-0.03):(0.01-0.03):(0.8-1.2):(95-105):(0.4-0.6), and the reaction is carried out under the condition of stirring at room temperature for 20-30 hours.

[0019] Preferably, in step S2, when preparing the carbon nanotube ammonium salt dispersion, the mass ratio of modified carbon nanotubes, deionized water, and hydrochloric acid is (1-2):(80-120):(10-15), and the reaction conditions are stirring at room temperature for 20-40 minutes.

[0020] Preferably, the hydrochloric acid comprises 36.5 wt% hydrochloric acid.

[0021] Preferably, in step S2, when preparing MMT / CNTs, the mass ratio of montmorillonite, deionized water, and ammonium salt dispersion of carbon nanotubes is (8-12):(150-250):(91-137), and the reaction conditions are stirring at 70-90℃ for 20-30 hours.

[0022] Preferably, in step two, the mass ratio of glycerol 1,3-diglycerol diacrylate, isocyanate-based MMT / CNTs, catalyst, and toluene is (34.8-36.5):(15-17):(0.02-0.04):(300-500), and the reaction conditions are under nitrogen protection and at a temperature of 70-90°C for 60-100 min.

[0023] Preferably, the catalyst comprises dibutyltin lauryl laurate.

[0024] Preferably, in step three, the mass ratio of maleic anhydride, initiator, acetone, alkenyl-containing MMT / CNTs and POE is (2-4):(0.5-1):(30-40):(3-5):100, the extrusion temperature is 180-200℃, and the screw speed is 150-250 r / min.

[0025] Preferably, the initiator comprises dicumyl peroxide.

[0026] Preferably, in step four, the mass ratio of modifier, additive, and PA6 is (8-12):(1-2):100, and the melt blending temperature is 260-280℃;

[0027] The additives include lubricants and antioxidants.

[0028] Preferably, the mass ratio of the lubricant to the antioxidant is 1:1;

[0029] The lubricant includes calcium stearate, and the antioxidant includes antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]).

[0030] The present invention also discloses a high-strength, high-toughness modified plastic particle prepared by the above-described method for preparing high-strength, high-toughness modified plastic particles.

[0031] An application of a high-strength, high-toughness modified plastic particle as described above.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] In this invention, PA6 is used as the matrix material. The modified plastic particles have high strength. The tubular carbon nanotubes and the layered montmorillonite in the nanofiller MMT / CNTs can synergistically enhance and toughen PA6. The polyolefin elastomer POE molecules contain both crystalline ethylene segments and amorphous octene soft chain coiled structures, which have good toughening and modification capabilities. By introducing the nanofiller MMT / CNTs and the polyolefin elastomer POE, the strength and toughness of PA6 can be effectively improved. After modification, the nanofiller MMT / CNTs can be chemically grafted with the polyolefin elastomer POE, thereby realizing the construction of a synergistic network of reinforcing and toughening nanofillers and toughening elastomers. The modified plastic particles prepared have high strength and high toughness.

[0034] In the process of preparing a modifier from nanofiller MMT / CNTs and polyolefin elastomer POE, MMT / CNTs react with diisocyanate through the hydroxyl groups on their surface to obtain isocyanate-based MMT / CNTs. Isocyanate groups are introduced onto the surface of MMT / CNTs, and then react with the hydroxyl groups on the glycerol 1,3-diglycerol diacrylate molecule to obtain alkenyl-containing MMT / CNTs. Under the action of an initiator, the carbon-carbon double bonds introduced on the surface of MMT / CNTs and the carbon-carbon double bonds on the maleic anhydride molecule undergo graft bonding with the POE molecular chain. The incorporation of maleic anhydride can react with the amino groups at the end of the PA6 molecular chain, thereby improving the compatibility between POE and PA6, and thus improving the compatibility between the nanofiller MMT / CNTs grafted onto the POE molecular chain and PA6.

[0035] In addition, glycerol 1,3-diglyceryl alcohol diacrylate is a polyolefin compound. While grafting nanofillers MMT / CNTs onto POE molecular chains, it can also achieve moderate cross-linking between POE molecular chains to form a three-dimensional cross-linked network structure, thereby further improving the toughness of PA6-based modified plastic particles. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the reaction between MMT / CNTs and toluene-2,4-diisocyanate to prepare isocyanate-based MMT / CNTs in Example 1 of the present invention.

[0037] Figure 2 This is a schematic diagram of the reaction between isocyanate-based MMT / CNTs and glycerol 1,3-diglycerol diacrylate to prepare alkenyl-containing MMT / CNTs in Example 1 of the present invention.

[0038] Figure 3 The graph shows the tensile properties test results of the modified plastic particles prepared in Examples 1-5 and Comparative Examples 1-2 of this invention.

[0039] Figure 4 The graph shows the impact resistance test results of the modified plastic particles prepared in Examples 1-5 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment discloses a method for preparing high-strength and high-toughness modified plastic particles, including the following steps:

[0043] Step 1: Add MMT / CNTs to toluene and stir at 300 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:50:0.05:400. React at 75℃ for 100 min under nitrogen protection. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0044] MMT / CNTs are prepared by the following steps:

[0045] S1. N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole, and carboxylated multi-walled carbon nanotubes were added to N,N-dimethylformamide and ultrasonically dispersed at 50 kHz for 30 min to obtain a carbon nanotube dispersion. Triethylenetetramine was added to the carbon nanotube dispersion. The mass ratio of N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole, carboxylated multi-walled carbon nanotubes, N,N-dimethylformamide, and triethylenetetramine was 0.02:0.02:1:95:0.5. The mixture was stirred at 200 rpm for 24 h at room temperature. After the reaction was completed, the mixture was filtered, washed three times with toluene, and dried in a vacuum drying oven at 50 ℃ to constant weight to obtain modified carbon nanotubes.

[0046] S2. Modified carbon nanotubes were added to deionized water and ultrasonically dispersed at a frequency of 50 kH for 30 min. 36.5 wt% hydrochloric acid was added dropwise at a stirring speed of 200 r / min under stirring conditions. The mass ratio of modified carbon nanotubes, deionized water and 36.5 wt% hydrochloric acid was 1.5:100:12. The mixture was stirred at room temperature and at a stirring speed of 200 r / min for 24 h to obtain a carbon nanotube ammonium salt dispersion.

[0047] Montmorillonite was added to deionized water and ultrasonically dispersed at 50 kHz for 30 min. Then, carbon nanotube ammonium salt dispersion was added. The mass ratio of montmorillonite, deionized water, and carbon nanotube ammonium salt dispersion was 10:200:113.5. The mixture was stirred at 80 ℃ and 200 r / min for 24 h. After the reaction was completed, the mixture was filtered, washed three times with ethanol, and dried in a vacuum drying oven at 50 ℃ to constant weight to obtain MMT / CNTs.

[0048] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 34.8:15:0.02:300. React under nitrogen protection at 70℃ for 100 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0049] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0050] The mixture was added to POE. The mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 2:0.5:30:3:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 180℃ and a screw speed of 250r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0051] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 8:0.5:0.5:100. The melt-blending temperature is 260℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0052] Example 2

[0053] This embodiment discloses a method for preparing high-strength and high-toughness modified plastic particles, including the following steps:

[0054] Step 1: Add MMT / CNTs to toluene and stir and disperse at 250 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:70:0.1:600. React under nitrogen protection at 85℃ for 60 min. After the reaction is completed, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0055] The preparation method of MMT / CNTs is the same as in Example 1;

[0056] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 36.5:17:0.04:500. React under nitrogen protection at 90℃ for 60 min. After the reaction is completed, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0057] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0058] The mixture was added to POE. The mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 4:1:40:5:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 200℃ and a screw speed of 150r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0059] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 12:1:1:100. The melt-blending temperature is 280℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0060] Example 3

[0061] This embodiment discloses a method for preparing high-strength and high-toughness modified plastic particles, including the following steps:

[0062] Step 1: Add MMT / CNTs to toluene and stir and disperse at 250 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:55:0.06:450. React under nitrogen protection at 80℃ for 80 min. After the reaction is completed, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0063] The preparation method of MMT / CNTs is the same as in Example 1;

[0064] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 35.3:15.5:0.03:350. React under nitrogen protection at 80℃ for 80 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0065] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0066] The mixture was added to POE, and the mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 2.5:0.6:32:3.5:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 190℃ and a screw speed of 200 r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0067] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 9:0.6:0.6:100. The melt-blending temperature is 270℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0068] Example 4

[0069] This embodiment discloses a method for preparing high-strength and high-toughness modified plastic particles, including the following steps:

[0070] Step 1: Add MMT / CNTs to toluene and stir and disperse at 250 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:60:0.075:500. React under nitrogen protection at 80℃ for 80 min. After the reaction is completed, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0071] The preparation method of MMT / CNTs is the same as in Example 1;

[0072] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 35.7:16:0.03:400. React under nitrogen protection at 80℃ for 80 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0073] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0074] The mixture was added to POE, and the mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 3:0.75:35:4:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 190℃ and a screw speed of 200r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0075] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 10:0.75:0.75:100. The melt-blending temperature is 270℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0076] Example 5

[0077] This embodiment discloses a method for preparing high-strength and high-toughness modified plastic particles, including the following steps:

[0078] Step 1: Add MMT / CNTs to toluene and stir at 250 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:65:0.09:550. React at 80℃ for 80 min under nitrogen protection. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0079] The preparation method of MMT / CNTs is the same as in Example 1;

[0080] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 36.2:16.5:0.03:450. React under nitrogen protection at 80℃ for 80 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0081] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0082] The mixture was added to POE, and the mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 3.5:0.9:38:4.5:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 190℃ and a screw speed of 200 r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0083] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 11:0.9:0.9:100. The melt-blending temperature is 270℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0084] Comparative Example 1

[0085] This comparative example discloses a method for preparing high-strength and high-toughness modified plastic particles, comprising the following steps:

[0086] Step 1: Add MMT / CNTs to toluene and stir at 300 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:50:0.05:400. React at 75℃ for 100 min under nitrogen protection. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0087] The preparation method of MMT / CNTs is the same as in Example 1;

[0088] Step 2: Add 3-hydroxypropyl acrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of 3-hydroxypropyl acrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 13:15:0.02:300. React under nitrogen protection at 70℃ for 100 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0089] Step 3: Dissolve maleic anhydride and dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0090] The mixture was added to POE. The mass ratio of maleic anhydride, dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 2:0.5:30:1.9:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 180℃ and a screw speed of 250 r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0091] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 7.9:0.5:0.5:100. The melt-blending temperature is 260℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0092] Comparative Example 2

[0093] This comparative example discloses a method for preparing high-strength and high-toughness modified plastic particles, comprising the following steps:

[0094] Step 1: Add MMT / CNTs to toluene and stir at 300 r / min for 30 min. Then add toluene-2,4-diisocyanate and stannous octoate. The mass ratio of MMT / CNTs, toluene-2,4-diisocyanate, stannous octoate and toluene is 100:50:0.05:400. React at 75℃ for 100 min under nitrogen protection. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain isocyanate-based MMT / CNTs.

[0095] The preparation method of MMT / CNTs is the same as in Example 1;

[0096] Step 2: Add glycerol 1,3-diglyceryl alcohol diacrylate to toluene and stir and disperse at 300 r / min for 30 min. Then add isocyanate-based MMT / CNTs and dibutyltin laurylate. The mass ratio of glycerol 1,3-diglyceryl alcohol diacrylate, isocyanate-based MMT / CNTs, dibutyltin laurylate and toluene is 34.8:15:0.02:300. React under nitrogen protection at 70℃ for 100 min. After the reaction is complete, centrifuge. Wash the centrifuged precipitate three times with toluene and dry it in a vacuum drying oven at 40℃ to constant weight to obtain alkenyl-containing MMT / CNTs.

[0097] Step 3: Dissolve dicumyl peroxide in acetone, add alkenyl-containing MMT / CNTs, and stir and disperse at 300 r / min for 30 min to obtain a mixture.

[0098] The mixture was added to POE, and the mass ratio of dicumyl peroxide, acetone, alkenyl-containing MMT / CNTs and POE was 0.5:30:3:100. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 180℃ and a screw speed of 250r / min. After cooling, the mixture was pelletized to obtain the modifier.

[0099] Step 4: Melt-blend the modifier, calcium stearate, antioxidant 1010, and PA6. The mass ratio of modifier, calcium stearate, antioxidant 1010, and PA6 is 7.8:0.5:0.5:100. The melt-blending temperature is 260℃. Extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

[0100] In the above examples and comparative examples: the carboxylated multi-walled carbon nanotubes had a particle size of 30-50 nm and a length of 10-20 μm; the montmorillonite had a particle size of 2000 mesh; the POE contained 24%-28% octene and had a density of 0.87 g / cm³. 3 PA6 has a tensile strength of 71.4 MPa and a melting point of 225℃.

[0101] Test case

[0102] (1) Tensile properties: The modified plastic particles obtained in Examples 1-5 and Comparative Examples 1-2 were melted and injection molded to obtain test samples. The tensile strength of the test samples was determined according to the standard ASTM D638-2014 "Standard Test Method for Tensile Properties of Plastics". The test samples were type IV specimens with a total length of 115 mm, a narrow section length of 33 mm, a total width of 19 mm, a narrow section width of 6 mm, and a thickness of 4 mm. The tensile speed was 10 mm / min. The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105] As shown in Table 1, the modified plastic particles prepared by this invention have high strength. Using PA6 as the matrix material, the modified plastic particles exhibit high strength. The tubular carbon nanotubes and layered montmorillonite in the rigid nanofiller MMT / CNTs synergistically reinforce PA6, effectively compensating for the decrease in tensile strength of the rigid polymer material PA6 caused by the introduction of the flexible toughening polymer POE. Furthermore, the modifier can react with the amino groups at the ends of the PA6 molecular chain through the incorporated maleic anhydride groups, thereby improving the compatibility between the modifier and PA6, and further enhancing the compatibility between the nanofiller MMT / CNTs grafted onto the POE molecular chain and PA6, resulting in a further increase in tensile strength. Compared to Example 1, in Comparative Example 1, 3-hydroxypropyl acrylate was used instead of glycerol 1,3-diglyceryl alcohol diacrylate when preparing the modifier. This prevented cross-linking between POE molecular chains, avoiding potential interface defects caused by the cross-linking network restricting the deformation of the POE matrix. As a result, the tensile strength of the modified plastic particles increased. In Comparative Example 2, maleic anhydride was not added when preparing the modifier. The modifier could not chemically bond with PA6, reducing the compatibility between the rigid nanofiller MMT / CNTs and PA6, and thus decreasing the tensile strength of the modified plastic particles.

[0106] (2) Impact resistance: The cantilever beam notched impact strength of the modified plastic particles prepared in Examples 1-5 and Comparative Examples 1-2 was determined according to the standard GB / T1843-2008 "Determination of cantilever beam impact strength of plastics". The test results are shown in Table 2.

[0107] Table 2

[0108]

[0109] As shown in Table 2, the modified plastic particles prepared by this invention exhibit high toughness. In preparing the modified plastic particles, PA6 is used as the matrix material. By introducing the flexible toughening polymer POE into PA6, the toughness of PA6 can be effectively improved. The tubular carbon nanotubes and the layered montmorillonite in the introduced nanofillers MMT / CNTs synergistically toughen PA6. Furthermore, the glycerol 1,3-diglycerol diacrylate introduced during the preparation of the modifier is a polyolefin compound. This not only enables the grafting of the nanofillers MMT / CNTs with the POE molecular chains but also achieves moderate cross-linking between the POE molecular chains, forming a three-dimensional cross-linked network structure. This cross-linked structure more effectively induces shear yielding or cavitation in the matrix, promoting plastic deformation of the PA6 matrix such as crazing and shear banding, absorbing impact energy, thereby further improving the toughness of the PA6-based modified plastic particles. Compared with Example 1, in Comparative Example 1, 3-hydroxypropyl acrylate was used instead of glycerol 1,3-diglyceryl alcohol diacrylate when preparing the modifier, that is, cross-linking did not occur between POE molecular chains, the toughness of the modified plastic particles decreased, and the impact strength was weakened; in Comparative Example 2, maleic anhydride was not added when preparing the modifier, the modifier could not chemically bond with PA6, the compatibility between rigid nanofillers MMT / CNTs and PA6 decreased, and the impact strength also decreased.

[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified plastic particle having high strength and high toughness, characterized by comprising the steps of: Includes the following steps: ​ Step 1: Add MMT / CNTs to toluene, stir to disperse, then add diisocyanate and catalyst, react, centrifuge, wash, and dry to obtain isocyanate-based MMT / CNTs; The mass ratio of MMT / CNTs, diisocyanate, catalyst and toluene is 100:(50-70):(0.05-0.1):(400-600), and the reaction conditions are under nitrogen protection and at 75-85℃ for 60-100 min. Step 2: Add glycerol 1,3-diglycerol glycol diacrylate to toluene, stir and disperse, then add isocyanate-based MMT / CNTs and catalyst, and react. After the reaction is complete, centrifuge, wash, and dry to obtain alkenyl-containing MMT / CNTs. The mass ratio of glycerol 1,3-diglycerol diacrylate, isocyanate-based MMT / CNTs, catalyst, and toluene was (34.8-36.5):(15-17):(0.02-0.04):(300-500), and the reaction conditions were: under nitrogen protection, at a temperature of 70-90℃ for 60-100 min. The catalyst includes dibutyltin laurylate; Step 3: Dissolve maleic anhydride and initiator in acetone, add alkenyl-containing MMT / CNTs, stir and disperse to obtain a mixture; The mixture is added to POE, mixed, extruded through a twin-screw extruder, cooled, and pelletized to obtain the modifier; The mass ratio of maleic anhydride, initiator, acetone, alkenyl-containing MMT / CNTs and POE is (2-4):(0.5-1):(30-40):(3-5):100, the extrusion temperature is 180-200℃, and the screw speed is 150-250 r / min; the initiator includes dicumyl peroxide. Step 4: Melt-blend the modifier and additives with PA6, extrude, cool, and pelletize to obtain high-strength and high-toughness modified plastic particles.

2. The method for preparing high-strength and high-toughness modified plastic particles according to claim 1, characterized in that, The MMTs / CNTs in step one, It is prepared by the following steps: S1. N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole, and carboxylated multi-walled carbon nanotubes were added to N,N-dimethylformamide and ultrasonically dispersed to obtain a carbon nanotube dispersion. Triethylenetetramine was added to the carbon nanotube dispersion and reacted. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified carbon nanotubes. S2. Modified carbon nanotubes were added to deionized water, ultrasonically dispersed, and hydrochloric acid was added dropwise under stirring. The reaction was stirred to obtain a carbon nanotube ammonium salt dispersion. Montmorillonite was added to deionized water and ultrasonically dispersed. Then, carbon nanotube ammonium salt dispersion was added and reacted. After the reaction was completed, the mixture was filtered, washed, and dried to obtain MMT / CNTs.

3. The method for preparing high-strength and high-toughness modified plastic particles according to claim 2, characterized in that, In S1, the mass ratio of N,N'-diisopropylcarbodiimide, 1-hydroxybenzotriazole, carboxylated multi-walled carbon nanotubes, N,N-dimethylformamide, and triethylenetetramine is (0.01-0.03):(0.01-0.03):(0.8-1.2):(95-105):(0.4-0.6), and the reaction is carried out under the condition of stirring at room temperature for 20-30 h.

4. The method for preparing high-strength and high-toughness modified plastic particles according to claim 2, characterized in that, In S2, when preparing the carbon nanotube ammonium salt dispersion, the mass ratio of modified carbon nanotubes, deionized water, and hydrochloric acid is (1-2):(80-120):(10-15), and the reaction conditions are stirring at room temperature for 20-40 min. When preparing MMT / CNTs, the mass ratio of montmorillonite, deionized water, and ammonium salt dispersion of carbon nanotubes is (8-12):(150-250):(91-137), and the reaction conditions are stirring at 70-90℃ for 20-30h.

5. The method for preparing high-strength and high-toughness modified plastic particles according to claim 1, characterized in that, In step four, the mass ratio of modifier, additive, and PA6 is (8-12):(1-2):100, and the melt blending temperature is 260-280℃. The additives include lubricants and antioxidants.

6. A high-strength, high-toughness modified plastic particle prepared by the method for preparing high-strength, high-toughness modified plastic particles as described in any one of claims 1-5.

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