Rare earth master batch for chinlon 66 as well as preparation method and application of rare earth master batch

Abstract

The invention discloses a rare earth master batch for chinlon 66. The rare earth master batch is prepared from the following raw materials in percentage by weight: 56-89% of polyamide 66 slices, 10-30% of nanoscale rare earth powder and 1-2.5% of a single hyperdispersant, wherein the polyamide 66 slices are one of bright polyamide 66 slices, semi-dull polyamide 66 slices and full-dull polyamide 66 slices; the titanium dioxide content of the bright polyamide 66 slices is smaller than or equal to 0.05%, the titanium dioxide content of the semi-dull polyamide 66 slices is 0.1-0.6%, and the titanium dioxide content of the full-dull polyamide 66 slices is larger than or equal to 1.2%. According to the invention, the rare earth powder with a specific particle size and a specific type and the hyperdispersant are used in the composition, so that the rare earth master batch has good dispersibility and pelletizability. The master batch produced by the invention is blended and spun with polyamide 66 slices according to a specific proportion, so that the elongation at break of the polyamide 66 can be effectively reduced, the stability of downstream weaving is enhanced, the color of the polyamide 66 and subsequent dyeing are basically not influenced, and meanwhile, the polyamide 66 fiber is endowed with good antibacterial and anti-ultraviolet properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyamides, and particularly relates to a rare earth masterbatch for nylon 66, a preparation method thereof, and an application thereof. Background Art

[0002] Polyamide 66 is an artificial synthetic fiber produced by melt spinning after polymerization of adipic acid and hexamethylenediamine. Compared with polyamide 6 of the same polyamide series, polyamide 66 has better heat resistance, wear resistance, and strength. In the past, due to the low output and high price of hexamethylenediamine, one of its production raw materials, the development progress was slow. In recent years, with the breakthrough of domestic hexamethylenediamine technology, polyamide 66 has witnessed unprecedented rapid development. Currently, due to its excellent properties, polyamide 66 has received extensive attention in the fields of civil and military spinning fibers. Although there are more and more modification studies, the problem of low breaking strength and high elongation at break has led to its failure to reach the ideal physical property indexes. An excessively high elongation at break will cause the fiber to be easily deformed after weaving, which is not conducive to maintaining its dimensional stability, thereby affecting its downstream applications and promotion.

[0003] Currently, the method for reducing the elongation at break of polyamide 66 is generally to increase the draw ratio during the spinning process, and the fiber is fully stretched by the difference in the rotational speed of the godet rollers. For example, Chinese Patent with Application No. CN201810240403.1 discloses a production method of ultra-high strength nylon 66 fiber. The main steps of the production method are: nylon 66 salt solution - concentration polymerization - spinning - cooling - oiling - drawing and setting - winding. This invention mainly makes the fiber fully stretched by increasing the draw ratio during the spinning process, but this method has certain limitations. The draw ratio cannot be infinitely increased. An excessively high draw ratio may lead to too large spinning tension or yarn breakage, ultimately resulting in non-spinnability. Considering the limitations of improving the elongation at break from the equipment side, if a modified masterbatch can be designed from the raw material side and the addition ratio can be adjusted according to actual needs to improve the elongation at break of polyamide 66, it will have important development prospects. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a rare earth masterbatch for nylon 66. When applied to nylon 66, it can greatly reduce its elongation at break and basically has no influence on color and subsequent dyeing.

[0005] The technical solution of the present invention is as follows:

[0006] One of the purposes of the present invention is to provide a rare earth masterbatch for nylon 66, which is composed of the following raw materials in weight percentages: 56 - 89% of polyamide 66 chips, 10 - 30% of nano-level rare earth powder, and 1 - 2.5% of a single-type superdispersant.

[0007] Further, the polyamide 66 chips are one of bright polyamide 66 chips, semi-dull polyamide 66 chips, and full-dull polyamide 66 chips; the titanium dioxide content of the bright polyamide 66 chips is ≤0.05%, the titanium dioxide content of the semi-dull polyamide 66 chips is 0.1 - 0.6%, and the titanium dioxide content of the full-dull polyamide 66 chips is ≥1.2%.

[0008] Further, the water content of the polyamide 66 chips is 800 - 1400 ppm, the extractables are ≤0.3%, the molecular weight is 24000 - 34000, and the relative viscosity range is 2.45 - 2.70.

[0009] Further, the nano-scale rare earth powder is cerium oxide, with a particle size of 100 - 200 nm and a purity of ≥99.99%.

[0010] Further, the melting point of the single-type superdispersant is 150°C, and the thermal decomposition degree at 300°C is ≤97%.

[0011] Further, the water content of the rare earth masterbatch for nylon 66 is 600 - 800 ppm, and the relative viscosity is 2.16 - 2.22.

[0012] The second object of the present invention is to provide a method for preparing a rare earth masterbatch for nylon 66, comprising the following steps:

[0013] S1: Pre-mix the nano-scale rare earth powder and the single-type superdispersant in a set ratio to obtain a mixture;

[0014] S2: Feed the materials in an automatic feeding manner. Automatically sample the polyamide 66 chips through the main feeding port, feed the mixture obtained in step S1 from the side feeding port, and successively pass through melting and plasticizing, screw conveying and shearing, water-cooling pelletizing, vibration screening, and air-blowing drying in a parallel co-rotating twin-screw extruder to obtain the rare earth masterbatch for nylon 66.

[0015] Further, in step S2, the melting and plasticizing process is divided into eleven temperature zones and a head temperature zone, and the temperature is controlled within the range of 250 - 275°C.

[0016] The third object of the present invention is to provide an application of any of the above rare earth masterbatches for nylon 66 or the rare earth masterbatch for nylon 66 prepared according to any of the above methods in nylon 66.

[0017] Further, the addition amount of the rare earth masterbatch for nylon 66 in nylon 66 is ≤10%.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention provides a rare earth masterbatch for nylon 66, which uses polyamide 66 slices as the main base material of the rare earth masterbatch. Nylon 66 has good heat resistance and wear resistance, and is not easy to break at low temperatures. The rare earth masterbatch in the present invention achieves the effect of reducing the elongation at break by increasing the crystallinity of the fiber. In the process of melt spinning cooling and forming, the presence of nano cerium oxide rare earth particles within a specific particle size range provides a certain amount of nucleating agent for the crystallization of nylon 66, which plays a role in inducing crystallization, increases the proportion of its crystallization area, and makes the molecules more closely arranged, thereby reducing the elongation at break of nylon 66. On the other hand, the nano cerium oxide rare earth particles can form hydrogen bonds with the long chains of nylon 66 molecules, play a firm role, limit the sliding between the long chain molecules in the fiber, and thus also reduce the elongation at break of nylon 66 to a certain extent.

[0020] 2. In the present invention, polyamide 66 slices can be divided into three types: glossy, semi-matte and fully matte according to the titanium dioxide content. After optimized design, the rare earth masterbatch for nylon 66 is basically not affected by titanium dioxide and can be applied to various scene requirements.

[0021] 3. In the present invention, cerium oxide rare earth nanopowder with a particle size of 100-200nm is selected as the effective component of rare earth masterbatch for nylon 66. Within this particle size range, it can ensure good dispersibility of the material in polyamide 66 slices, reduce equipment blockage, reduce the frequency of equipment cleaning and maintenance, improve the overall efficiency of the production line, and ensure the stability of fiber quality. At the same time, the cerium oxide rare earth nanopowder has a high purity (≥99.99%), and the color is white to slightly yellow. After being used in the production of rare earth masterbatch for nylon 66, the masterbatch is dark white. After the present invention controls the appropriate addition ratio for spinning nylon 66, it will basically not affect the color of the yarn and the subsequent dyeing, and will also enhance the antibacterial properties of the yarn. And cerium oxide, as an inorganic substance, has a melting point of 2600℃ and has excellent thermal stability. In terms of solubility, cerium oxide is insoluble in water and alkaline solvents like polyamide 66 slices. The similar properties make the two have better combination and also make the final masterbatch have good stability. On the other hand, cerium oxide rare earth material, as a UV absorber, can also give nylon 66 a certain anti-UV effect, giving downstream products better outdoor promotion advantages in their applications.

[0022] 4. In the present invention, the dispersant selected is a single-type hyperdispersant with a melting point of 150°C and a thermal decomposition degree ≤ 97% at 300°C. The melting point of this single-type hyperdispersant is lower than that of polyamide 66 chips, enabling it to melt earlier and play an ideal dispersing role. The relatively high thermal decomposition temperature enables it to maintain its own structure unchanged under different working conditions such as granulation and spinning, achieving the most ideal dispersing effect. The granulation and spinning temperatures of polyamide 66 are higher than those of polyamide 6, which is widely used at present. In the selection of dispersants, high-temperature tolerance is an important evaluation index. Compared with small-molecule dispersants, the single-type hyperdispersant has a higher thermal decomposition temperature. This single-type hyperdispersant does not need to be pre-compounded in advance during production, ensuring the unity of the product quality of the rare earth masterbatch and reducing product quality problems caused by fluctuations in the quality of the dispersant. This dispersant can significantly improve the wettability and dispersion stability of nano-scale rare earth powder in the polyamide 66 melt, ensuring that there will be no intermittent bar-breaking phenomenon during the extrusion and drawbar process of the extruder granulator and maintaining production stability.

[0023] 5. A preparation method of a rare earth masterbatch for polyamide 66 provided by the present invention uses a twin-screw extruder to melt and blend polyamide 66 chips and nano-ceria rare earth with a special particle size range, appropriately reducing the side-feed inlet, subsequent heating zone temperature, and die head temperature, reducing the oxidation problem of polyamide 66 chips caused by excessive temperature, making the melt discharge more stable, reducing bar-breaking caused by filament phenomenon, and increasing the duration of continuous and stable production.

[0024] 6. The rare earth masterbatch for polyamide 66 provided by the present invention can solve the problem of the too large elongation at break of current polyamide 66 when added to polyamide 66 in a lower content, and it has good application prospects in polyamide 66. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a comparative thermogravimetric analysis diagram of the single-type hyperdispersant and two commercially available dispersants in Example 1 of the present invention;

[0026] Figure 2 It is a physical diagram of the rare earth masterbatch for polyamide 66 prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following combines preferred embodiments and refers to the attached Figure 1-2, a further description of the present invention is given. In the scope disclosed in the present invention, the endpoints and any values of the scope are not limited to the exact scope or value. These scopes or values should be understood to include values close to these scopes or values; for numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein; the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels; the experimental methods in the following examples, unless otherwise specified, are conventional methods.

[0028] Example 1

[0029] This example provides a rare earth masterbatch for nylon 66, which is composed of the following raw materials by weight percentage: 68.5% of polyamide 66 chips, 30% of nano-level rare earth powder, and 1.5% of single-type superdispersant.

[0030] In this example, the polyamide 66 chips are bright polyamide 66 chips. The content of titanium dioxide in the bright polyamide 66 chips is 0.05%, and the water content of the polyamide 66 chips is 800 ppm, the extractable matter is 0.25%, the molecular weight is 24,000, and the relative viscosity is 2.45.

[0031] In this example, the nano-level rare earth powder is cerium oxide, the particle size is 100 nm, and the purity ≥ 99.99%.

[0032] In this example, the melting point of the single-type superdispersant is 150 °C, and the thermal decomposition degree at 300 °C ≤ 97%. Figure 1 is the thermogravimetric analysis comparison chart of the single-type superdispersant in this example and two commercially available dispersants. It can be seen from Figure 1 that the single-type superdispersant in this example has good thermal stability.

[0033] This example also provides a preparation method for the rare earth masterbatch for nylon 66, including the following steps:

[0034] S1: Premix the nano-level rare earth powder and the single-type superdispersant evenly according to the set ratio to obtain a mixture;

[0035] S2: Feed materials in an automatic feeding manner. Feed the polyamide 66 chips automatically through the main feeding port, feed the mixture obtained in step S1 from the side feeding port, and successively pass through melting and plasticizing, screw transmission and shearing, water cooling and pelletizing, vibration screening, and air drying in a parallel co-rotating twin-screw extruder to obtain the rare earth masterbatch for nylon 66.

[0036] In this embodiment, in step S2, the melting and plasticizing process is divided into eleven temperature zones and a head temperature zone, and the temperature control of each temperature zone is as follows: the first zone is 265°C; the second zone is 275°C; the third zone is 275°C; the fourth zone is 275°C; the fifth zone is 270°C; the sixth zone is 265°C; the seventh zone is 260°C; the eighth zone is 255°C; the ninth zone is 250°C; the tenth zone is 245°C; the eleventh zone is 240°C; the head is 275°C.

[0037] The rare earth masterbatch for nylon 66 prepared in this embodiment is in granular form, as Figure 2 shown. The moisture content of this masterbatch is 800 ppm, and the relative viscosity is 2.16.

[0038] Example 2

[0039] This embodiment provides a rare earth masterbatch for nylon 66, which is composed of the following raw materials in weight percentages: 84% of polyamide 66 chips, 15% of nanoscale rare earth powder, and 1% of a single-type super-dispersant.

[0040] In this embodiment, the polyamide 66 chips are semi-dull polyamide 66 chips. The titanium dioxide content of the semi-dull polyamide 66 chips is 0.3%, and the water content of the polyamide 66 chips is 1000 ppm, the extractable matter is 0.3%, the molecular weight is 30000, and the relative viscosity is 2.70.

[0041] In this embodiment, the nanoscale rare earth powder is cerium oxide, with a particle size of 200 nm and a purity of ≥99.99%. The melting point of the single-type super-dispersant is 150°C, and the thermal decomposition degree at 300°C is ≤97%.

[0042] This embodiment also provides a preparation method for the rare earth masterbatch for nylon 66, including the following steps:

[0043] S1: Premix the nanoscale rare earth powder and the single-type super-dispersant evenly according to the set ratio to obtain a mixture;

[0044] S2: Feed the materials in an automatic feeding manner. Feed the polyamide 66 chips automatically through the main feeding port, feed the mixture obtained in step S1 from the side feeding port, and successively pass through melting and plasticizing, screw transmission and shearing, water-cooled pelletizing, vibration screening, and air-blowing drying in a parallel co-rotating twin-screw extruder to obtain the rare earth masterbatch for nylon 66.

[0045] In this embodiment, in step S2, the melting and plasticizing process is divided into eleven temperature zones and a head temperature zone, and the temperature control of each temperature zone is as follows: the first zone is 250°C; the second zone is 270°C; the third zone is 265°C; the fourth zone is 265°C; the fifth zone is 250°C; the sixth zone is 260°C; the seventh zone is 250°C; the eighth zone is 235°C; the ninth zone is 235°C; the tenth zone is 230°C; the eleventh zone is 230°C; the head is 250°C.

[0046] The moisture content of the rare earth masterbatch for nylon 66 prepared in this example is 750 ppm, and the relative viscosity is 2.18.

[0047] Example 3

[0048] This example provides a rare earth masterbatch for nylon 66, which is composed of the following raw materials by weight percentage: 87.5% of polyamide 66 chips, 10% of nano-scale rare earth powder, and 2.5% of single-type super-dispersant.

[0049] In this example, the polyamide 66 chips are full dull polyamide 66 chips. The titanium dioxide content of the full dull polyamide 66 chips is 1.5%, and the water content of the polyamide 66 chips is 1400 ppm, the extractable matter is 0.2%, the molecular weight is 34000, and the relative viscosity is 2.60.

[0050] In this example, the nano-scale rare earth powder is cerium oxide, the particle size is 150 nm, the purity ≥ 99.99%, the melting point of the single-type super-dispersant is 150 °C, and the thermal decomposition degree at 300 °C ≤ 97%.

[0051] This example also provides a preparation method of the rare earth masterbatch for nylon 66, including the following steps:

[0052] S1: Pre-mix the nano-scale rare earth powder and the single-type super-dispersant evenly according to the set ratio to obtain a mixture;

[0053] S2: Feed materials in an automatic feeding manner. Feed the polyamide 66 chips automatically through the main feeding port, feed the mixture obtained in step S1 from the side feeding port, and successively pass through melting and plasticizing, screw transmission and shearing, water cooling and pelletizing, vibration screening and air drying in a parallel co-rotating twin-screw extruder to obtain the rare earth masterbatch for nylon 66.

[0054] In this example, in step S2, the melting and plasticizing process is divided into eleven temperature zones and a head temperature zone, and the temperature control of each temperature zone is as follows: the first segment is 250 °C; the second segment is 270 °C; the third segment is 265 °C; the fourth segment is 265 °C; the fifth segment is 250 °C; the sixth segment is 260 °C; the seventh segment is 250 °C; the eighth segment is 235 °C; the ninth segment is 235 °C; the tenth segment is 230 °C; the eleventh segment is 230 °C; the head is 250 °C.

[0055] The moisture content of the rare earth masterbatch for nylon 66 prepared in this example is 790 ppm, and the relative viscosity is 2.22.

[0056] Example 4

[0057] The rare earth masterbatch for nylon 66 prepared in Example 2 was applied to nylon 66. Among them, the proportion of the rare earth masterbatch for nylon 66 was 5%, and the remaining components were 95% of polyamide 66 semi-dull chips.

[0058] The spinning screw was divided into 5 temperature zones, which were, in sequence from the feeding end to the extrusion end: 290 °C, 300 °C, 292 °C, 294 °C, 295 °C. The die head temperature was 292 °C, and the draw ratio was controlled at 1.6. Finally, nylon 66 yarn was produced.

[0059] Example 5

[0060] It was basically the same as Example 4, except that in this example, the proportion of the rare earth masterbatch for nylon 66 was 10%, and the remaining components of the nylon 66 yarn were 90% of polyamide 66 semi-dull chips.

[0061] Comparative Example 1

[0062] The difference from Example 2 was that: the raw material ratio in the rare earth masterbatch for nylon 66 in this comparative example was different.

[0063] The rare earth masterbatch for nylon 66 in this comparative example was composed of the following raw materials by weight percentage: 67% of polyamide 66 chips, 30% of nano-level rare earth powder, and 3% of single-type super-dispersant.

[0064] Comparative Example 2

[0065] The difference from Example 2 was that: the raw material of the rare earth masterbatch for nylon 66 in this comparative example did not contain a single-type super-dispersant.

[0066] The rare earth masterbatch for nylon 66 in this comparative example was composed of the following raw materials by weight percentage: 85% of polyamide 66 chips, 15% of nano-level rare earth powder.

[0067] Comparative Example 3

[0068] The difference from Example 4 was that: the raw material of the nylon 66 yarn in this comparative example was 100% of polyamide 66 semi-dull chips.

[0069] Evaluation of implementation effects

[0070] The following is a specific test on the masterbatches prepared in Examples 1-3 and Comparative Examples 1-2, and the nylon 66 yarns prepared in Examples 4, 5 and Comparative Example 3, further illustrating the excellent effects achieved by the present invention:

[0071] The following table is a statistical table of the physical property test results of the rare earth masterbatch for nylon 66 prepared in Examples 1-3:

[0072] Table 1 Statistical table of physical property test results of rare earth masterbatch for nylon 66

[0073] Item Melting point (℃) 100-grain weight (g) Viscosity Amino group (mmol / kg) Example 1 260.2 2.2234 2.16 42.43 Example 2 259.6 2.2276 2.18 42.13 Example 3 261.1 2.2248 2.22 41.88

[0074] As can be seen from the above table, in the preparation of the rare earth masterbatch of Comparative Example 1, due to the excessive content of the single-type superdispersant, the screw shearing effect was reduced, and high-frequency intermittent bar breaking occurred during the extrusion and drawing process, resulting in abnormal production and inability to stably produce the rare earth masterbatch for nylon 66.

[0075] In Comparative Example 2, due to the lack of a single-type superdispersant, the mixing effect of nano-ceria rare earth powder and polyamide 66 was poor and uneven, and high-frequency intermittent bar breaking occurred during the extrusion and drawing process, resulting in abnormal production and inability to stably produce the rare earth masterbatch for nylon 66.

[0076] The following table is a statistical table of the spinning conditions of nylon 66 in Examples 4 and 5 and Comparative Example 3 and the physical property test results of the obtained nylon 66 yarns:

[0077] Table 2 Statistical table of the spinning conditions of nylon 66 and the physical property test results of nylon 66 yarns

[0078]

[0079] The following table is a statistical table of the color measurement data results of the white nylon 66 yarns prepared in Examples 4 and 5 and Comparative Example 3:

[0080] Table 3 Statistical table of the color measurement data results of white nylon 66 yarns

[0081]

[0082] As can be seen from the above test results, adding the rare earth masterbatch for nylon 66 prepared by the present invention to nylon 66 can effectively reduce the elongation at break of the white nylon 66 yarn, improve the performance of the nylon 66 fiber, and enable it to be better applied to more life scenarios. Through color comparison, it is found that when the addition amount of the rare earth masterbatch for nylon 66 ≤ 5%, the addition of the rare earth masterbatch for nylon 66 has very little influence on the color of the white nylon 66 yarn.

[0083] The following table is a statistical table of the antibacterial rate results of the white nylon 66 yarns prepared in Examples 4 and 5:

[0084] Table 4 Statistical table of the antibacterial rate results of nylon 66 rare earth yarns

[0085]

[0086] As can be seen from the above test results, adding the rare earth masterbatch for nylon 66 prepared by the present invention to nylon 66 can endow the nylon 66 fiber with good antibacterial properties, enabling it to better meet the antibacterial requirements of mass daily clothing.

[0087] The following table is a statistical table of the anti-ultraviolet performance results of the white polyamide 66 yarns prepared in Examples 4 and 5 and Comparative Example 3:

[0088] Table 5 Statistical table of the anti-ultraviolet performance results of white polyamide 66 yarns

[0089]

[0090]

[0091] It can be seen from the above test results that adding the rare earth masterbatch prepared by the present invention to polyamide 66 can endow the polyamide 66 fiber with good anti-ultraviolet performance, enabling it to better meet the outdoor sun protection and anti-ultraviolet performance requirements of daily clothing for the public.

[0092] In summary, the rare earth masterbatch for polyamide 66 provided by the present invention can be applied to polyamide 66 with a small addition amount, and can greatly improve the problem of too large elongation at break of polyamide 66, basically having no impact on its color, and enabling the polyamide 66 fiber to have good antibacterial and anti-ultraviolet properties. The present invention is of great significance for the promotion of future differentiated filament fibers of polyamide 66.

[0093] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention.

Claims

1. A rare earth masterbatch for nylon 66, characterized in that: The invention is composed of the following raw materials in percentage by weight: 56-89% of polyamide 66 slices, 10-30% of nanometer rare earth powder and 1-2.5% of single type super dispersant.

2. The rare earth masterbatch for nylon 66 according to claim 1, characterized in that: The polyamide 66 slice is one of a glossy polyamide 66 slice, a semi-dull polyamide 66 slice and a fully-dull polyamide 66 slice.

3. The rare earth masterbatch for nylon 66 according to claim 2, characterized in that: The titanium dioxide content of the bright polyamide 66 slice is ≤0.05%, the titanium dioxide content of the semi-dull polyamide 66 slice is 0.1-0.6%, and the titanium dioxide content of the fully-dull polyamide 66 slice is ≥1.2%; the water content of the polyamide 66 slice is 800-1400ppm, the extractable matter is ≤0.3%, the molecular weight is 24000-34000, and the relative viscosity ranges from 2.45 to 2.

70.

4. The rare earth masterbatch for nylon 66 according to claim 1, characterized in that: The nano-grade rare earth powder is cerium oxide, with a particle size of 100-200nm and a purity of ≥99.99%.

5. The rare earth masterbatch for nylon 66 according to claim 1, characterized in that: The single type hyperdispersant has a melting point of 150° C. and a thermal decomposition degree of ≤97% at 300° C.

6. A rare earth masterbatch for nylon 66 according to any one of claims 1 to 5, characterized in that: The moisture content of the rare earth masterbatch for nylon 66 is 600-800ppm, and the relative viscosity is 2.16-2.

22.

7. The method for preparing a rare earth masterbatch for nylon 66 according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: premixing the nano-rare earth powder and the single-type hyperdispersant in a set ratio to obtain a mixture; S2: The polyamide 66 slices are automatically fed through the main feeding port, and the mixture obtained in step S1 is fed from the side feeding port. The mixture is subjected to melt plasticization, screw transmission and shearing, water-cooled pelletizing, vibration screening and air drying in a parallel co-rotating twin-screw extruder to obtain the rare earth masterbatch for nylon 66.

8. The method for preparing rare earth masterbatch for nylon 66 according to claim 7, characterized in that: In step S2, the melt plasticization process is divided into eleven temperature zones and a die temperature zone, and the temperature is controlled within the range of 250-275°C.

9. Use of a rare earth masterbatch for nylon 66 according to any one of claims 1 to 8 or a rare earth masterbatch for nylon 66 prepared by the method of claim 8 or 9 in nylon 66.

10. The use of a rare earth masterbatch for nylon 66 in nylon 66 according to claim 9, characterized in that: The amount of the rare earth masterbatch for nylon 66 added to nylon 66 is ≤10%.

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