Nylon 12 modified plastic as well as preparation method and application thereof

Abstract

The invention provides nylon 12 modified plastic as well as a preparation method and application thereof. The preparation raw materials comprise 60-98 wt% of nylon 12, 0-14 wt% of a liquid plasticizer, 1-20 wt% of a solid toughening agent, 0.1-1 wt% of a solid antioxidant, 0.1-1 wt% of a heat stabilizer, 0-1 wt% of a light stabilizer, 0-2 wt% of a coloring agent and 0.03-1 wt% of a liquid descaling agent. And the neck mold scale cleaning times are reduced, the possibility of generating large-particle impurity points is reduced, the neck mold scale cleaning time is prolonged, the product quality is improved, and the method is suitable for the fields of automobile pipeline preparation and the like.

Description

Technical Field

[0001] The invention belongs to the field of polymer material modified products and relates to a nylon 12 modified plastic and a preparation method and application thereof. Background Art

[0002] Nylon 12 is a long carbon chain nylon polymer, which is obtained by bulk ring-opening polymerization with laurolactam as raw material. Enterprises with the production capacity of nylon 12 and its modified products mainly include Evonik, Arkema, Emmans, Wanhua Chemical, etc. Nylon 12 has excellent properties, such as good impact resistance and chemical resistance, low melting point and density, and good high temperature resistance. Due to the above excellent properties of nylon 12, it can usually be used in automotive pipelines, toothbrush wires, powder spraying materials, 3D printing materials, automotive pipeline cable sheaths and other fields.

[0003] The materials used to make automobile pipes need to have the following properties: oil corrosion resistance, high temperature resistance, aging resistance, good toughness and elasticity, wear resistance, pressure resistance, explosion resistance (sudden pressure increase) and other properties. Commonly used materials for automobile brake hoses include polyundecanoic acid amide, nylon 12, etc. Among the above materials, nylon 12 has better performance and is reasonably priced, making it suitable for use as a brake pipe material. In order to make nylon 12 more suitable as a material for automobile pipes, it needs to be modified, and plasticizers, toughening agents, antioxidants, heat stabilizers and light stabilizers need to be added to the base resin. In addition, colorants need to be added to adjust the color.

[0004] Since the production process of nylon 12 is bulk polymerization, and the viscosity of nylon 12 melt is relatively high, as the viscosity increases during the polymerization process, its mass transfer and heat transfer become gradually difficult. Therefore, it is inevitable that there are residual monomers. In addition, the polymerization reaction of nylon 12 is carried out under high temperature conditions, so some side reactions such as decomposition and degradation are inevitable. Therefore, there are often some residual monomers in nylon 12 products. For example, "Physical and Chemical Inspection (Chemical Volume)-Determination of Four Monomers in Nylon 12 by Gas Chromatography" (Volume 55, 2019) has detected that nylon 12 contains monomers such as lauryl lactam, caprolactam, benzenesulfonamide, and dioctyl adipate. Although these monomers do exist in the material, due to their small content, they do not affect the various properties and use of the material. However, when modifying the nylon 12 material, serious die fouling often occurs.

[0005] The above-mentioned monomers often have the characteristics of low melting point and easy sublimation. When nylon 12 is modified or reprocessed, part of the residual monomer will sublimate from the exhaust port of the extruder due to sublimation, and a trace amount will remain at the die outlet after being cooled after sublimation at the die outlet of the extruder. Over time, it is easy to form die scale, and oxidize in the air to darken or even blacken the color. When the die scale accumulates to a certain amount, it will fall off the die, forming large dark spots attached to the material strip, which will be mixed into the product after pelletizing, causing the product quality to decline. In order to speed up the sublimation of residual monomers in nylon 12, many plastic production personnel have adopted the method of adding shear elements to the screw to increase the melt temperature and make the residual monomer sublime quickly. However, nylon 12 itself is not resistant to excessive shearing, and it will also cause the material itself to decompose and produce a large number of large particle impurity points. Therefore, the method of adding shear modules is not applicable. Therefore, it is necessary to prevent or prolong the generation of die fouling in a way that does not destroy the molecular structure of nylon 12 and does not affect the performance of nylon 12 itself, so as to solve the above technical problems. Summary of the invention

[0006] The object of the present invention is to provide a nylon 12 modified plastic and a preparation method thereof, which has the advantages of being less likely to produce large particle impurities during long-term production and having a good material appearance.

[0007] Another object of the present invention is to provide the use of the nylon 12 modified plastic for preparing automobile pipelines, which has the advantages of a long die fouling period during the material production process and no need to frequently stop the machine to clean the die.

[0008] A nylon 12 modified plastic comprises 60-98 wt% of nylon 12, 0-14 wt% of a liquid plasticizer, 1-20 wt% of a solid toughening agent, 0.1-1 wt% of a solid antioxidant, 0.1-1 wt% of a heat stabilizer, 0-1 wt% of a light stabilizer, 0-2 wt% of a colorant and 0.03-1 wt% of a liquid descaling agent.

[0009] In the present invention, the nylon 12 is a polymer obtained by ring-opening polymerization of lauryl lactam, and the relative viscosity of the nylon 12 is 1.9-2.3.

[0010] In the present invention, the solid antioxidant includes one or more of copper salt antioxidants, phosphate antioxidants, hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants and polymer antioxidants; preferably, the antioxidant is one or more of copper salt antioxidants, hindered phenol antioxidants and phosphite antioxidants.

[0011] In the present invention, the solid toughening agent includes a copolymer of a polar monomer and a polymer elastomer; preferably, the polar monomer includes one or more of maleic anhydride and its derivatives, acrylates and their derivatives, and glycidyl methacrylate; preferably, the polymer elastomer includes one or more of polyolefins, ethylene-α-olefin copolymers, ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, styrene-butadiene copolymers, polyethylene-polystyrene-polypropylene terpolymers, polyethylene-polypropylene-polybutene terpolymers, styrene-acrylonitrile copolymers, and ethylene-acrylate copolymers.

[0012] In the present invention, the heat stabilizer includes one or more of an amide stabilizer such as Nylostab S-EED, sodium montanate, calcium montanate, tribasic lead sulfate, calcium stearate, and zinc stearate.

[0013] In the present invention, the light stabilizer includes one or more of an ultraviolet absorber, a free radical scavenger and a light shielding agent; optionally, the anti-ultraviolet absorber includes one or more of UV312, UV329, UV234, UV360, 770, 944, 622 and S-EED.

[0014] In the present invention, the colorant includes but is not limited to masterbatch and color powder.

[0015] In the present invention, the liquid plasticizer is one or more of butylene phthalate, diethyl phthalate, N-butylbenzenesulfonamide, diisobutyl nylonate, and dioctyl nylonate.

[0016] In the present invention, the liquid descaling agent is a hydrocarbon mixture or a silicon-containing polymer liquid. Preferably, the hydrocarbon mixture is a hydrocarbon mixture with 18 to 30 carbon atoms, and its straight-chain alkane content is 80% to 95%, and the total content of branched alkanes and monocyclic cycloalkanes with long side chains is less than 20%; the silicon-containing polymer liquid is silicone oil, including but not limited to methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil, and cyanide silicone oil. One or more.

[0017] The present invention also provides a twin-screw extruder, comprising a feeding section, a melt plasticizing section, a natural exhaust end, a mixing section, a compression section, a filtering section, a head section, and a descaling agent injection section, which is located at the front end of the head section and the rear end of the filtering section; preferably, a toothed disk is added near the descaling agent injection port for uniformly mixing the melt and the descaling agent.

[0018] The preparation method of the nylon 12 modified plastic of the present invention comprises the following steps: mixing the raw material components in a high-speed mixer, putting the materials into a buffer hopper and feeding them into the twin-screw extruder for melt granulation.

[0019] Preferably, the twin-screw extruder has an aspect ratio of 32 to 56, preferably an aspect ratio of 36 to 48.

[0020] The twin-screw extruder includes a main machine and an auxiliary machine. The main machine is a motor, a coupling, a gear box, a barrel, and a head in the extrusion direction. The barrel is divided into 9 zones, namely, a feeding section A, a melting and plasticizing section B, a natural exhaust end C, a mixing section I D, a mixing section II E, a compression section F, a filtering section G, a descaling agent injection section H, and a head section J, in the extrusion direction. The auxiliary machine includes a buffer hopper connected to the barrel A zone and a high mixer above it, a condenser connected to the barrel B zone and a pure water tank below it, a water ring vacuum pump connected to the E zone, a screen changer connected to the G zone and a hydraulic press below it, and a water tank connected to the J zone. A natural exhaust port is set in the C zone, a liquid plasticizer injection port is set in the D zone, a vacuum exhaust port is set in the F zone, a liquid descaling agent injection port is set in the H zone, and a die is set in the J zone. The mixed material is fed into the feeding section of the twin-screw extruder through a buffer hopper or a weight loss scale and a forced feeder. After the fed material is melted in the plasticizing section of the extruder and exhausted at the natural exhaust port, a liquid plasticizer is injected behind the natural exhaust port to plasticize the melted material. After the melt is plasticized and continuously sheared and melted, excess gas is discharged through the vacuum exhaust port, and the vacuum degree is -0.03 to -0.09MPaG; after the melt is vacuum-exhausted and enters the screen changer to remove large particle impurities, a liquid descaling agent is injected after the screen changer and before the die to reduce or eliminate die fouling. The twin-screw extruder for producing this composite material is equipped with an appropriate amount of shear modules in the plasticizing section, liquid plasticizer injection section and mixing section, so that the composite material can be plasticized or mixed evenly. A toothed disk is added near the liquid descaling agent injection port to evenly mix the melt and the descaling agent.

[0021] During the melt granulation process, the speed of the twin-screw extruder is 200 rpm to 600 rpm, preferably 300 to 450 rpm; the temperature of the feeding section of the twin-screw extruder is room temperature to 200°C, the temperature from the plasticizing section to the die is 230 to 300°C, preferably 240 to 280°C; the die temperature is 260 to 320°C;

[0022] The positive effect of the present invention is that adding a liquid descaling agent behind the twin-screw extruder screen changer can reduce the amount of residual sheet precipitation at the die, thereby reducing the number of times the die scale is cleaned and greatly reducing the possibility of excessive large particle impurity points caused by die scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the extruder DETAILED DESCRIPTION

[0024] In order to better understand the technical solution of the present invention, the content of the present invention is further described below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0025] The main raw materials involved in the embodiments and comparative examples are as follows:

[0026] Nylon 12, Wanhua Chemical, Wanamid L3000;

[0027] Solid toughening agent, DuPont, USA, N416, chemical name EPDM-g-MAH;

[0028] Solid toughening agent, Jiayirong, SOG-03, chemical name POE-methacrylate dehydrated glycerol copolymer;

[0029] Solid antioxidant, Brueggemann, H3376, organic copper salt;

[0030] Solid antioxidant, Lianlong, 1098, hindered phenol antioxidant;

[0031] Solid antioxidant, Lianlong, 168, phosphite antioxidant;

[0032] Thermal stabilizer, Clariant, Nylostab S-EED, amide stabilizer;

[0033] Light stabilizer, BASF, UV312, anti-ultraviolet additive;

[0034] Colorant, Cabot, UN2014, black masterbatch;

[0035] Liquid plasticizer, Puweilun, PP024, N-butylbenzenesulfonamide;

[0036] Liquid descaling agent, Dow Corning, OFX-8803, silicone-containing polymer liquid;

[0037] Liquid descaling agent, Daliang Chemical, BY-26, hydrocarbon mixture (hydrocarbon mixture is a mixture of hydrocarbons with carbon atoms of about 18 to 30, of which straight-chain alkanes are about 82%, branched alkanes are 5%, and monocyclic cycloalkanes with long side chains are 13%).

[0038] The structure of the twin screw extruder used is as follows Figure 1As shown, the twin-screw extruder includes a main machine and an auxiliary machine. The main machine is composed of a motor, a coupling, a gear box, a barrel, and a die head in the extrusion direction. The barrel is divided into 9 zones, namely, a feeding zone A, a melting and plasticizing zone B, a natural exhaust end C, a mixing zone I D, a mixing zone II E, a compression zone F, a filtering zone G, a descaling agent injection zone H, and a die head zone J, in the extrusion direction. The auxiliary machine includes a buffer hopper connected to the barrel zone A and a high mixer above it, a condenser connected to the barrel zone B and a pure water tank below it, a water ring vacuum pump connected to the E zone, a screen changer connected to the G zone and a hydraulic press below it, and a water tank connected to the J zone. A natural exhaust port is provided in the C zone, a liquid plasticizer injection port is provided in the D zone, a vacuum exhaust port is provided in the F zone, a liquid descaling agent injection port is provided in the H zone, and a die is provided in the J zone.

[0039] Example 1

[0040] The solid materials were mixed uniformly in a high-speed mixer according to the following composition: 77.5 wt% of nylon 12 (L3000), 8 wt% of solid toughening agent (N416), 0.3 wt% of solid antioxidant (H3376), and 0.1 wt% of heat stabilizer (Nylostab S-EED).

[0041] like Figure 1 As shown, a twin-screw extruder with an aspect ratio of 32 is used, the main screw speed is set to 200rpm, the feeding section temperature of the twin-screw extruder is 160°C, the temperature from the plasticizing section to the die is 230°C, and the die temperature is 260°C; the above-mentioned mixed materials are added to a buffer hopper and enter the twin-screw extruder from the buffer hopper; the gas generated during the extrusion process is discharged from the natural exhaust port, and 14wt% of the liquid plasticizer (PP024) is injected into the feed port behind the natural exhaust port through a liquid metering scale, and after mixing with the melt in the mixing section, large particles of impurities are filtered out through a screen changer; 0.1wt% of the liquid descaling agent (OFX-8803) is injected into the feed port between the screen changer and the die through a liquid metering scale, and the screw at the feed port is equipped with a toothed disk for uniform mixing, and the material is extruded through the die, cooled in a water tank, stretched, dehydrated by an air knife, and pelletized to form a finished product.

[0042] The cleaning time of the die fouling in the production process is 24 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by this method is less than 2 / 100g (refer to SH / T+1541.1-2019+Plastic particle appearance test method+Part 1: Visual inspection method).

[0043] Example 2

[0044] The solid materials were mixed uniformly in a high-speed mixer according to the following composition: 86.1wt% of nylon 12 (L3000), 1wt% of solid toughening agent (SOG-03), 0.3wt% of solid antioxidant (1098), 0.2wt% of solid antioxidant (168), 0.2wt% of heat stabilizer (Nylostab S-EED), 0.2wt% of light stabilizer (UV-312), and 1.5wt% of colorant (UN2014).

[0045] The twin-screw extruder with an aspect ratio of 40 is set to have a main screw speed of 300 rpm, a feeding section temperature of 170°C, a temperature from the plasticizing section to the die head of 240°C, and a die temperature of 270°C; the above-mentioned uniformly mixed materials are added into a buffer hopper, and enter the twin-screw extruder from the buffer hopper; the gas generated during the extrusion process is discharged from the natural exhaust port, and 10 wt% of a liquid plasticizer (PP024) is injected into the feed port behind the natural exhaust port through a liquid metering scale, mixed with the melt in the mixing section, and then filtered out large particles of impurities through a screen changer; 0.5 wt% of a liquid descaling agent (OFX-8803) is injected into the feed port between the screen changer and the die through a liquid metering scale, and the screw at the feed port is equipped with a toothed disk for uniform mixing, extruded through the die, cooled in a water tank, stretched, dehydrated with an air knife, and pelletized to form a finished product.

[0046] The cleaning time of the die fouling in the production process is 48 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 1 / 100g.

[0047] Example 3

[0048] The solid materials were mixed uniformly in a high-speed mixer according to the following composition: 74.97 wt% nylon 12 (L3000), 20 wt% solid toughening agent (N416), 0.8 wt% solid antioxidant (1098), 0.2 wt% solid antioxidant (168), 1 wt% heat stabilizer (Nylostab S-EED), 1 wt% light stabilizer (UV312), and 2 wt% colorant (UN2014).

[0049] A twin-screw extruder with an aspect ratio of 44 is used, the main screw speed is 400rpm, the temperature of the feeding section of the twin-screw extruder is 180°C, the temperature from the plasticizing section to the die is 260°C, and the die temperature is 280°C; the above-mentioned uniformly mixed materials are added into a buffer hopper, and enter the twin-screw extruder from the buffer hopper; the gas generated during the extrusion process is discharged from the natural exhaust port, and large particles of impurities are filtered out through a screen changer; 0.03wt% of a liquid descaling agent (OFX-8803) is injected into the feed port between the screen changer and the die through a liquid metering scale, and the screw at the feed port is equipped with a toothed disk for uniform mixing, and the material is extruded through the die, cooled in a water tank, stretched, dehydrated with an air knife, and pelletized to form a finished product.

[0050] The cleaning time of the die fouling in the production process is 16 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 3 / 100g.

[0051] Example 4

[0052] The solid materials were mixed uniformly in a high-speed mixer according to the following composition: 65.75 wt% nylon 12 (L3000), 20 wt% solid toughening agent (SOG-03), 0.05 wt% solid antioxidant (1098), 0.05 wt% solid antioxidant (168), and 0.1 wt% thermal stabilizer (Nylostab S-EED).

[0053] The main screw of the twin-screw extruder has an aspect ratio of 56, a main screw speed of 600 rpm, a feeding section temperature of 190°C, a temperature from the plasticizing section to the die head of 280°C, and a die temperature of 300°C; the uniformly mixed materials are added into a buffer hopper and enter the twin-screw extruder from the buffer hopper; the gas generated during the extrusion process is discharged from a natural exhaust port, 14 wt% of a liquid plasticizer (PP024) is injected into a feed port behind the natural exhaust port through a liquid metering scale, mixed with the melt in a mixing section, and then filtered out large particles of impurities through a screen changer; 0.05 wt% of a liquid descaling agent (BY-26) is injected into a feed port between a screen changer and a die through a liquid metering scale, a screw at the feed port is equipped with a toothed disk for uniform mixing, extruded through a die, cooled in a water tank, stretched, dehydrated with an air knife, and pelletized to form a finished product.

[0054] The cleaning time of the die fouling in the production process is 16 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 1 / 100g.

[0055] Example 5

[0056] The solid materials were mixed evenly in a high mixer according to the following composition: 93.5wt% nylon 12 (L3000), 1wt% solid toughening agent (N416), 0.5wt% solid antioxidant (1098), 0.5wt% solid antioxidant (168), 1wt% heat stabilizer (S-EED), 1wt% light stabilizer (UV-312), 2wt% colorant (black masterbatch PE2718).

[0057] The main screw of the twin-screw extruder has an aspect ratio of 48, a main screw speed of 450 rpm, a feeding section temperature of 200°C, a plasticizing section to die temperature of 300°C, and a die temperature of 320°C; the uniformly mixed materials are added into a buffer hopper and enter the twin-screw extruder from the buffer hopper; the gas generated during the extrusion process is discharged from a natural exhaust port, and large particles of impurities are filtered out through a screen changer; 0.5 wt% of a liquid descaling agent (BY-26) is injected into a feed port between a screen changer and a die through a liquid metering scale, and a screw at the feed port is equipped with a toothed disk for uniform mixing, and the material is extruded through the die, cooled in a water tank, stretched, dehydrated with an air knife, and pelletized to form a finished product.

[0058] The cleaning time of the die fouling in the production process is 24 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 1 / 100g.

[0059] Comparative Example 1

[0060] The only difference between this comparative example and Example 2 is that no liquid descaling agent is added (L3000 is used to make up 100%).

[0061] The cleaning time of the die fouling in the production process is 2 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 5 / 100g.

[0062] Comparative Example 2

[0063] The only difference between this comparative example and Example 3 is that the liquid descaling agent is injected together with the liquid plasticizer addition port.

[0064] The cleaning time of the die fouling in the production process is 4 hours / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 4 / 100g.

[0065] Comparative Example 3

[0066] The only difference between this comparative example and Example 5 is that the liquid descaling agent is not added by injecting it into the feed port between the screen changer and the die (liquid descaling agent injection section) through a liquid metering scale, but is mixed in other solid components except the liquid plasticizer.

[0067] The cleaning time of the die fouling in the production process is 1 hour / time. The finished product can be used to prepare automobile pipelines. The number of large particle impurity points with a diameter of 0.1 to 0.2 mm in the special material for automobile pipelines prepared by the method is less than 6 / 100g.

[0068] The examples show that adding a liquid descaling agent can prolong the cleaning time of die scale accumulation and reduce the number of large particle impurity points. For example, in Example 2, the cleaning time of die scale accumulation is 48 hours / time, and the number of large particle impurity points is less than 1 / 100g, while in Comparative Example 1, when no liquid descaling agent is added, the cleaning time is only 2 hours / time, and the number of large particle impurity points is less than 5 / 100g. The modified plastic is used to prepare automobile pipelines, and has the advantages of reducing die scale accumulation and improving product quality.

[0069] It should be noted that the above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A nylon 12 modified plastic, characterized in that: The preparation raw materials include 60-98wt% of nylon 12, 0-14wt% of liquid plasticizer, 1-20wt% of solid toughening agent, 0.1-1wt% of solid antioxidant, 0.1-1wt% of heat stabilizer, 0-1wt% of light stabilizer, 0-2wt% of colorant and 0.03-1wt% of liquid descaling agent.

2. The nylon 12 modified plastic according to claim 1, characterized in that: The relative viscosity of the nylon 12 is 1.9-2.

3.

3. The nylon 12 modified plastic according to claim 1 or 2, characterized in that: The liquid descaling agent is a hydrocarbon mixture or a silicon-containing polymer liquid; preferably, the hydrocarbon mixture is a hydrocarbon mixture with 18 to 30 carbon atoms, the straight-chain alkane content of which is 80% to 95%, and the branched alkanes and monocyclic cycloalkanes with long side chains have a total content of less than 20%; and / or, the silicon-containing polymer liquid is silicone oil, preferably one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil, and cyanide silicone oil.

4. The nylon 12 modified plastic according to any one of claims 1 to 3, characterized in that: The liquid plasticizer is one or more of butylene phthalate, diethyl phthalate, N-butylbenzenesulfonamide, diisobutyl nylonate, and dioctyl nylonate.

5. The nylon 12 modified plastic according to any one of claims 1 to 4, characterized in that: The solid toughening agent includes a copolymer of a polar monomer and a polymer elastomer; Preferably, the polar monomer includes one or more of maleic anhydride and its derivatives, acrylate and its derivatives, and glycidyl methacrylate; Preferably, the polymer elastomer includes one or more of polyolefins, ethylene-α-olefin copolymers, ethylene-propylene copolymers, ethylene-propylene-non-conjugated diene copolymers, styrene-butadiene copolymers, polyethylene-polystyrene-polypropylene terpolymers, polyethylene-polypropylene-polybutene terpolymers, styrene-acrylonitrile copolymers and ethylene-acrylate copolymers.

6. The nylon 12 modified plastic according to any one of claims 1 to 5, characterized in that: The solid antioxidant includes one or more of copper salt antioxidants, phosphate antioxidants, hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants and polymer antioxidants; preferably, the antioxidant is one or more of copper salt antioxidants, hindered phenol antioxidants and phosphite antioxidants.

7. The nylon 12 modified plastic according to any one of claims 1 to 6, characterized in that: The heat stabilizer includes one or more of amide stabilizers, sodium montanate, calcium montanate, tribasic lead sulfate, calcium stearate, and zinc stearate; and / or, the light stabilizer includes one or more of ultraviolet absorbers, free radical scavengers, and light shielding agents; preferably, the anti-ultraviolet absorber includes one or more of UV312, UV329, UV234, UV360, 770, 944, 622, and S-EED; and / or, the colorant includes masterbatch and color powder.

8. A twin-screw extruder, comprising a feeding section, a melt-plasticizing section, a natural exhaust end, a mixing section, a compression section, a filtering section and a head section, characterized in that: It also includes a descaling agent injection section, which is located at the front end of the head section and the rear end of the filtering section; preferably, a toothed disk is added near the descaling agent injection port for uniformly mixing the melt and the descaling agent.

9. The method for preparing nylon 12 modified plastic according to any one of claims 1 to 7, characterized in that: The prepared raw materials are mixed in a high-speed mixer and then melt-granulated by the twin-screw extruder according to claim 8; Preferably, the twin-screw extruder has a rotation speed of 200 rpm to 600 rpm, more preferably 300 to 450 rpm; The aspect ratio of the twin-screw extruder is 32-56, preferably 36-48; the temperature of the feeding section of the twin-screw extruder is room temperature to 200°C, the temperature from the plasticizing section to the die is 230-300°C, preferably 240-280°C; the die temperature is 260-320°C.

10. The method according to claim 9, characterized in that After the components except the liquid plasticizer and the descaling agent are uniformly mixed by a high-speed mixer, they are dropped into the feeding section of the twin-screw extruder through a buffer hopper; the liquid plasticizer is injected from the rear of the natural exhaust end in the middle of the screw extruder through a liquid metering scale; the liquid descaling agent is injected from the descaling agent injection section.

11. The nylon 12 modified plastic according to any one of claims 1 to 7 or the nylon 12 modified plastic prepared by the preparation method according to any one of claims 9 to 10, wherein the product is used for preparing automobile pipelines.

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