Whitening nylon 6 masterbatch and method for preparing the same

Abstract

The application discloses a kind of whitening nylon 6 master batches and preparation method thereof, belong to color master batch preparation technical field;The application combines the specific optical effect of absorption and reflection with the basic principle of chromatics, designs a new type of nylon 6 master batch preparation raw material combination consisting of titanium dioxide, phthalocyanine blue, permanent purple RL pigment, dispersing agent, wherein titanium dioxide has high refractive index, more visible light is reflected and refracted to make nylon 6 reach extinction and present white effect, phthalocyanine blue absorbs and reflects specific wavelength of light to present blue specific effect, while permanent purple RL pigment absorbs most of blue light and green light band, so that red light band and the purple light contained therein are reflected out, the synergistic optical effect of raw material combination not only significantly improves the brightness of mixed light, but also produces uniform white light, under the stable dispersion state of dispersing agent, nylon 6 master batch is prepared using the raw material combination, and the whiteness of white master batch can be improved after light absorption and refraction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of color master batch preparation, and particularly relates to a whitening nylon 6 master batch and a preparation method thereof. BACKGROUND

[0002] Nylon is a widely used engineering plastic, which has good comprehensive performance, including mechanical properties, heat resistance, wear resistance, chemical resistance and self-lubricity, low friction coefficient, certain flame retardancy, easy processing, etc. It is widely used for glass fiber and other filler filling and strengthening modification to improve performance and expand application range. At present, the common method for preparing nylon is to first mix monomers of semi-aromatic diacid and dibasic aliphatic amine with water and then perform a prepolymerization reaction under inert gas conditions, and then perform a solid phase tackifying reaction or a melt tackifying reaction on the obtained prepolymer. Due to the close melting point and decomposition temperature of nylon, it is very easy to yellow under high temperature conditions during synthesis. The yellowed nylon has certain limitations in application, and therefore, the research on the improvement of the whiteness of nylon has become an important topic.

[0003] At present, the traditional method for improving the whiteness of nylon mainly involves directly adding a powder-like fluorescent whitening agent to the nylon matrix, but this method may form local concentration differences in the material due to uneven dispersion, resulting in unstable whitening effect of the product. For example, in the prior art, a trace amount of titanium dioxide is added to the polymerization reaction of nylon 66 to improve the whiteness, but due to the strong memory and micro-fine of the ultra-fine titanium dioxide, the ultra-fine titanium dioxide is not easy to disperse in non-polar medium and is easy to agglomerate in polar medium, and the dispersibility and dispersion stability directly affect the quality and performance of the product.

[0004] In addition, the existing whitening agent may precipitate or migrate during high-temperature melt mixing due to poor compatibility with nylon resin, affecting the persistent whiteness and appearance quality of the product. Most whitening agents are significantly affected by temperature and humidity changes, which may cause the nylon product to accelerate discoloration due to increased hygroscopicity or light aging during use, thereby reducing the service life and market competitiveness of the product. Therefore, the natural color of the nylon product prepared by using the traditional whitening method is not pure white, and the product is easily affected by factors such as batch differences of raw materials and fluctuations in process conditions during production and processing, resulting in dark yellow color and insufficient whiteness of the product.

[0005] Japanese patent with publication number JP2011252247A and filing date of June 1, 2010 discloses an aramid fiber with improved brightness and its manufacturing method, using fluorescent dyes and swelling agents to dye the aramid fiber with improved whiteness. In addition, the aramid fiber is liquid dyed using fluorescent dyes and swelling agents, but this method, like the conventional method of directly adding a powdered fluorescent whitening agent, also cannot solve the defect that the whitening effect of the product is unstable due to uneven dispersion; Chinese patent with publication number CN103539935A and filing date of July 3, 2012 discloses a synthetic method comprising 1) feeding: adding binary acid monomers, binary amine monomers and other reaction aids into a reaction kettle in proportion; 2) aeration: filling the reaction kettle with a protective gas, and adding the pressure in the reaction kettle to 0.2-1.0 MPa, wherein the protective gas contains CO2, and the volume content of CO2 in the protective gas is 50-100%; 3) pre-polymerization: heating the reaction kettle to make the mixture in the reaction kettle pre-polymerize. The synthetic method of the present invention uses CO2 as the protective gas in the pre-polymerization stage, which reduces the opportunity of the amide bond contacting O2, thereby effectively preventing the color of the pre-polymer from turning yellow, but the reaction kettle needs to be vacuumed before aeration, and the polyamide prepared cannot avoid contacting O2 during use;

[0006] Therefore, it is necessary to study a kind of nylon 6 master batch that can effectively improve whiteness and overcome the unevenness of traditional fluorescent whitening agent and the oxidation defect of polyamide, which has practical application value in the field of nylon surface treatment research, greatly expands the application scenarios of nylon, and improves its market competitiveness. SUMMARY

[0007] To solve the problems in the prior art, the present application provides a whitening nylon 6 master batch and a preparation method thereof, a new type of nylon 6 master batch preparation raw material combination composed of titanium dioxide, phthalocyanine blue, permanent purple RL pigment and dispersant is designed, which significantly improves the brightness of mixed light, and produces uniform white light, and the whiteness of the white master batch can be improved after light absorption and refraction.

[0008] The technical scheme of the present application is as follows:

[0009] One of the objects of the present application is to provide a whitening nylon 6 master batch, which comprises the following components by weight fraction:

[0010] Nylon 6 chip: 61-66 parts;

[0011] Antioxidant: 0.4-0.5 parts;

[0012] Whitening agent: 0.5-0.6 parts;

[0013] Dispersant: 2-3 parts;

[0014] Titanium dioxide: 28-31 parts;

[0015] Phthalocyanine blue: 1.0-5.6 parts;

[0016] Permanent purple RL pigment: 0.02-0.08 parts;

[0017] The antioxidant is a composite antioxidant of any one of hindered phenolic antioxidants, phosphite antioxidants or a combination of both; the whitening agent is a pyrazoline type whitening agent.

[0018] Further, the dispersant is Tensachem NEW 400; the titanium dioxide is a white powder with a purity of 99.9%.

[0019] Further, the phthalocyanine blue is a blue powder with a purity of 99.9%; the permanent purple RL pigment is a purple powder with a purity of 99.9%.

[0020] The second object of the present application is to provide a preparation method of the whitening nylon 6 master batch, comprising the following steps:

[0021] S1, feeding nylon 6 chips from the main feeding port;

[0022] S2, weighing and mixing the antioxidant, whitening agent, dispersant, titanium dioxide, phthalocyanine blue and permanent purple RL pigment, and then feeding into the buffer bin after premixing, and then feeding into the hopper after discharging, and then spiral stirring to mix uniformly, and then feeding from the side feeding port;

[0023] S3, uniformly mixing the raw materials and feeding into the twin-screw extruder for melt mixing to obtain a whitening nylon 6 master batch melt;

[0024] S4, extruding the whitening nylon 6 master batch melt strip from the outlet of the twin-screw extruder, and then feeding into the granulator after cooling in the water cooling tank, and then selecting and air drying to prepare the whitening nylon 6 master batch.

[0025] Further, the rotation speed of the side feeding is controlled at 500-550 r / min.

[0026] Further, the length-diameter ratio of the twin-screw extruder is 40:1.

[0027] Further, the screw rotation speed of the twin-screw extruder is controlled at 500-600 r / min.

[0028] Further, the melt plasticizing process of the twin-screw extruder is divided into nine temperature zones and a die head temperature zone.

[0029] Further, the temperature of each section is controlled as follows: the first, second, third, fourth and fifth sections are 220-240 DEG C, the sixth, seventh, eighth and ninth sections are 180-210 DEG C, and the temperature of the machine head is 220-240 DEG C.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The present application combines the specific optical effect of absorption and reflection with the basic principles of color science to design a new nylon 6 master batch preparation raw material combination composed of titanium dioxide, phthalocyanine blue, permanent purple RL pigment and a dispersant. The titanium dioxide has a high refractive index, and reflects and refracts more visible light to make the nylon 6 appear white. The phthalocyanine blue absorbs and reflects specific wavelengths of light to produce a blue effect. The permanent purple RL pigment absorbs most of the blue and green light, allowing the red light and the purple light contained therein to be reflected. The synergistic optical effect of the raw material combination not only significantly improves the brightness of the mixed light, but also produces uniform white light. The use of the raw material combination to prepare the nylon 6 master batch can improve the whiteness of the white master batch under the condition that the dispersant maintains a stable dispersion state.

[0032] 2. The phthalocyanine blue has a specific optical effect on the surface of the master batch, reflecting about 450 nm of short-wavelength blue light and absorbing and reflecting specific wavelengths of light to produce a blue effect. When light is incident on the surface of the master batch containing phthalocyanine blue, the pigment molecules selectively absorb visible light wavelengths other than blue light, especially red and green light, and reflect or transmit blue light. However, if only phthalocyanine blue pigment is added during the preparation of the master batch, the white master batch will produce a small amount of green light when absorbing yellow light.

[0033] The permanent purple RL pigment exhibits red-violet color, meaning that it mainly absorbs short-wavelength blue light and green light, and strongly reflects or transmits the longer-wavelength red light portion and the purple light close to the red light region. When light is incident on the surface of an object containing permanent purple RL pigment, the pigment molecules absorb most of the blue and green light, and allow the red light and the purple light contained therein to be reflected, so that the color of the observed object surface appears red-violet.

[0034] The present application incorporates permanent purple RL pigment in the preparation of the raw material combination according to the basic principles of color science. When the amount of each pigment reaches a suitable condition, the refracted light meets the conditions of the three primary colors. The red, green and blue primary color light is mixed in a certain proportion and acts on the human visual system, thereby improving the brightness of the mixed light and achieving the whiteness improvement of the white master batch after the absorption and refraction process.

[0035] 3、Phthalo blue itself has no atom that can provide hydrogen bond acceptor, but there are four hydrogen bond acceptors in Everbrite RL. In the present application, the hydrogen bond acceptors (O and N on benzene ring) in Everbrite RL pigment can form hydrogen bonds with the amino groups in nylon 6, so that the charge distribution in the Everbrite RL molecule changes, which in turn causes the change of the molecular absorption spectrum of Everbrite RL, enhances the absorption of yellow light and weakens the absorption of blue light, and finally achieves the effect of whitening of the nylon 6 master batch. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A schematic diagram of the whitened nylon 6 master batch described in Example 1 of the present application;

[0037] Figure 2 A schematic diagram of the yarn of the whitened nylon 6 master batch described in Example 1 of the present application;

[0038] Figure 3 The infrared spectrum curve of the whitened nylon 6 master batch in the performance test of the present application, and the master batch of the nylon 6 to which only phthalo blue and Everbrite RL pigment are added, respectively. DETAILED DESCRIPTION

[0039] The present application will be further described in conjunction with preferred embodiments, and the endpoints and any values of the ranges disclosed in the present application are not limited to the precise range or value, and these ranges or values should be understood to include values close to these ranges or values; for numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0040] In the following examples, the experimental methods are conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified.

[0041] The materials, reagents, etc. used in the following examples can be obtained from commercial channels, unless otherwise specified.

[0042] Example 1

[0043] The present embodiment provides a whitened nylon 6 master batch, and the preparation method thereof comprises the following steps:

[0044] S1, feeding 65.44 parts of nylon 6 chips from the main feeding port;

[0045] S2, weighing and mixing 0.4 parts of antioxidant, 0.5 parts of whitening agent, 2.5 parts of dispersing agent, 30 parts of titanium dioxide, 1.08 parts of phthalo blue, and 0.08 parts of Everbrite RL pigment, and then feeding them into the buffer bin after premixing, and then feeding them into the hopper after being discharged, and then stirring them to be uniformly mixed by the screw, and then feeding them from the side feeding port, and then controlling the feeding speed at 510 r / min.

[0046] S3, uniformly mix the above raw materials and enter a twin-screw extruder with a length-diameter ratio of 40:1 for melt mixing to obtain a white nylon 6 master batch melt, wherein the screw rotation speed of the twin-screw extruder is controlled at 570 r / min, and is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth zones are 240°C, the sixth, seventh, eighth and ninth zones are 210°C, and the temperature of the die head is 240°C;

[0047] S4, extruding the white nylon 6 master batch melt strip from the outlet of the twin-screw extruder, and after cooling in a water tank, entering a granulator for granulation, vibration screening and air drying to prepare the white nylon 6 master batch;

[0048] S5, spinning the white nylon 6 master batch into POY SD 85D / 24F, then drawing into DTY SD 70D / 24F, winding into a yarn card for color measurement, and performing sample 1.

[0049] Example 2

[0050] The embodiment provides a white nylon 6 master batch, and a preparation method thereof includes the following steps:

[0051] S1, feeding 61.48 parts of nylon 6 chips from the main feeding port;

[0052] S2, weighing and blending 0.4 parts of antioxidant, 0.5 parts of whitening agent, 2.5 parts of dispersing agent, 30 parts of titanium dioxide, 5.1 parts of phthalocyanine blue, and 0.02 parts of permanent purple RL pigment, and after premixing, feeding into the buffer bin, and after feeding into the hopper, stirring with a spiral to mix uniformly, and feeding from the side feeding port, and the feeding rotation speed is controlled at 540 r / min;

[0053] S3, uniformly mix the above raw materials and enter a twin-screw extruder with a length-diameter ratio of 40:1 for melt mixing to obtain a white nylon 6 master batch melt, wherein the screw rotation speed of the twin-screw extruder is controlled at 570 r / min, and is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth zones are 240°C, the sixth, seventh, eighth and ninth zones are 210°C, and the temperature of the die head is 240°C;

[0054] S4, extruding the white nylon 6 master batch melt strip from the outlet of the twin-screw extruder, and after cooling in a water tank, entering a granulator for granulation, vibration screening and air drying to prepare the white nylon 6 master batch;

[0055] S5, spinning the white nylon 6 master batch into POY SD 85D / 24F, then drawing into DTY SD 70D / 24F, winding into a yarn card for color measurement, and performing sample 1.

[0056] Example 3

[0057] The embodiment provides a preparation method of whitened nylon 6 master batch, comprising the following steps:

[0058] S1, feeding 63.45 parts of nylon 6 chips from a main feeding port;

[0059] S2, weighing and blending 0.5 parts of an antioxidant, 0.5 parts of a whitening agent, 2 parts of a dispersing agent, 30 parts of titanium dioxide, 3.5 parts of phthalocyanine blue and 0.05 parts of permanent purple RL pigment, and feeding into a buffer bin after premixing, and then feeding into a hopper after being lowered, and then spirally stirring to be uniformly mixed, and feeding from a side feeding port;

[0060] S3, uniformly mixing the above raw materials and entering a double-screw extruder with a length-diameter ratio of 40:1 to perform melt mixing to obtain a whitened nylon 6 master batch melt, wherein the screw rotation speed of the double-screw extruder is controlled to be 550 r / min, the double-screw extruder is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth temperature zones are 235 DEG C, the sixth, seventh, eighth and ninth temperature zones are 205 DEG C, the temperature of the die head is 235 DEG C, and the feeding rotation speed is controlled to be 530 r / min;

[0061] S4, extruding the whitened nylon 6 master batch melt strip from the outlet of the double-screw extruder, cooling the strip in a water cooling tank, and then entering a granulator to perform granulation, vibration screening and air blowing drying to prepare the whitened nylon 6 master batch;

[0062] S5, spinning the whitened nylon 6 master batch into POY SD 85D / 24F, then performing draw texturing into DTY SD 70D / 24F, winding into a yarn card to measure color, and then performing sample 3.

[0063] Embodiment 4

[0064] The embodiment provides a preparation method of whitened nylon 6 master batch, comprising the following steps:

[0065] S1, feeding 63.45 parts of nylon 6 chips from a main feeding port;

[0066] S2, weighing and blending 0.5 parts of an antioxidant, 0.5 parts of a whitening agent, 2 parts of a dispersing agent, 30 parts of titanium dioxide, 3.5 parts of phthalocyanine blue and 0.05 parts of permanent purple RL pigment, and feeding into a buffer bin after premixing, and then feeding into a hopper after being lowered, and then spirally stirring to be uniformly mixed, and feeding from a side feeding port;

[0067] S3, uniformly mixing the above raw materials and entering a double-screw extruder with a length-diameter ratio of 40:1 to perform melt mixing to obtain a whitened nylon 6 master batch melt, wherein the screw rotation speed of the double-screw extruder is controlled to be 550 r / min, the double-screw extruder is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth temperature zones are 235 DEG C, the sixth, seventh, eighth and ninth temperature zones are 205 DEG C, the temperature of the die head is 235 DEG C, and the feeding rotation speed is controlled to be 530 r / min;

[0068] S4, extruding the white nylon 6 master batch melt strip from the twin-screw extruder outlet, and after the strip is cooled in a water tank, it is cut into particles in a granulator, screened by a vibrating screen, and dried by air blowing to prepare the white nylon 6 master batch;

[0069] S5, spinning the white nylon 6 master batch into POY SD 85D / 24F, then performing elastic recovery to be DTY SD 70D / 24F, winding into a yarn card to measure color, and performing sample 4.

[0070] Example 5

[0071] The embodiment provides a preparation method of white nylon 6 master batch, comprising the following steps:

[0072] S1, feeding 60.96 parts of nylon 6 chips from a main feeding port;

[0073] S2, weighing and blending 0.4 parts of an antioxidant, 0.5 parts of a whitening agent, 2.5 parts of a dispersing agent, 28 parts of titanium dioxide, 5.56 parts of phthalocyanine blue, and 0.08 parts of permanent purple RL pigment, and then feeding them into a buffer bin after premixing, and then feeding them into a hopper after being discharged, and then stirring them by a spiral to be uniformly mixed, and then feeding them from a side feeding port;

[0074] S3, uniformly mixing the above-mentioned raw materials and feeding them into a twin-screw extruder with a length-diameter ratio of 40:1 to be melt-mixed, to obtain a white nylon 6 master batch melt, wherein the screw rotation speed of the twin-screw extruder is controlled to be 500 r / min, the twin-screw extruder is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth temperature zones are 220 DEG C, the sixth, seventh, eighth and ninth temperature zones are 180 DEG C, the temperature of the die head is 220 DEG C, and the feeding rotation speed is controlled to be 550 r / min;

[0075] S4, extruding the white nylon 6 master batch melt strip from the twin-screw extruder outlet, and after the strip is cooled in a water tank, it is cut into particles in a granulator, screened by a vibrating screen, and dried by air blowing to prepare the white nylon 6 master batch;

[0076] S5, spinning the white nylon 6 master batch into POY SD 85D / 24F, then performing elastic recovery to be DTY SD 70D / 24F, winding into a yarn card to measure color, and performing sample 4.

[0077] Example 6

[0078] The embodiment provides a preparation method of white nylon 6 master batch, comprising the following steps:

[0079] S1, feeding 60.96 parts of nylon 6 chips from a main feeding port;

[0080] S2, 0.4 parts of antioxidant, 0.5 parts of whitening agent, 2.5 parts of dispersing agent, 31 parts of titanium dioxide, 3.6 parts of phthalocyanine blue, 0.05 parts of permanent purple RL pigment are weighed and mixed, and then put into the buffer bin after premixing, and then put into the hopper after screw stirring to mix uniformly, and then fed from the side feeding port;

[0081] S3, uniformly mix the above raw materials and melt mix in a twin-screw extruder with a length-diameter ratio of 40:1, wherein the screw rotation speed of the twin-screw extruder is controlled at 510 r / min, and the twin-screw extruder is divided into nine temperature zones and a die head temperature zone, the first, second, third, fourth and fifth zones are 225°C, the sixth, seventh, eighth and ninth zones are 190°C, and the temperature of the die head is 225°C, and the feeding rotation speed is controlled at 520 r / min;

[0082] S4, extrude the whitening nylon 6 master batch melt strip from the outlet of the twin-screw extruder, cool the strip in a water cooling tank, and then cut, vibrate and air dry in a granulator to prepare the whitening nylon 6 master batch;

[0083] S5, spin the whitening nylon 6 master batch into POY SD 85D / 24F, then into DTY SD 70D / 24F, and then measure the color of the yarn card to obtain sample 6.

[0084] Performance test

[0085] 1, use a Fourier transform infrared spectrometer to detect the whitening nylon 6 master batch, and the nylon 6 master batch added with phthalocyanine blue and permanent purple RL pigment respectively, and obtain the infrared spectrum curve as shown in Figure 3 .

[0086] From the infrared spectrum curve, it can be seen that phthalocyanine blue has a clear absorption valley between 400-500 nm, indicating that its absorption ability to blue light is weak;

[0087] From the infrared spectrum curve of permanent purple RL pigment, it can be seen that permanent purple RL pigment has an absorption peak between 500-550 nm, indicating that its absorption ability to green light is strong;

[0088] And in the infrared spectrum of the whitening master batch added with permanent purple RL pigment, it can be seen that the whitening master batch has a small absorption peak at 570-590 nm, indicating that its absorption ability to yellow light is strong, which proves that the hydrogen bond between permanent purple RL pigment and nylon 6 molecules causes the red shift of the original absorption peak of permanent purple RL pigment to 570-590 nm, so that the absorption ability of the whitening master batch to yellow light is enhanced.

[0089] 2, detect the color difference of samples 1-6 prepared in examples 1-6 respectively, and the detection results are shown in table 1:

[0090] Table 1 Index detection of products in examples and comparative examples

[0091]

[0092] From the above table, it can be seen that the whiteness of the nylon whitening master batch obtained in Example 1 is the highest among all examples, reaching 133.826.

[0093] 3, the sample 1 prepared in example 1 is detected for various physical indexes, and the detection results are shown in table 2:

[0094] Table 2 Physical index of nylon whitening yarn in example 1

[0095]

[0096] From the above table, it can be seen that the nylon whitening yarn of example 1 meets the normal yarn physical index standard.

[0097] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A whitening nylon 6 masterbatch characterized in that, The following components are included by weight parts: Nylon 6 chips: 61-66 parts; Antioxidant: 0.4-0.5 parts; Whitening agent: 0.5-0.6 parts; Dispersant: 2-3 parts; Titanium dioxide: 28-31 parts; Phthalocyanine blue: 1.0-5.6 parts; Permanent purple RL pigment: 0.02-0.08 parts; The antioxidant is a composite antioxidant of any one of hindered phenolic antioxidant, phosphite antioxidant or a combination of both; the whitening agent is a pyrazoline type whitening agent.

2. The whitening nylon 6 masterbatch according to claim 1, characterized in that, The dispersant is Tianchi NEW400; the titanium dioxide is a white powder with a purity of 99.9%.

3. The whitened nylon 6 masterbatch according to claim 1, wherein The phthalocyanine blue is a blue powder with a purity of 99.9%; the permanent purple RL pigment is a purple powder with a purity of 99.9%.

4. A process for the preparation of the whitening masterbatch of nylon 6 according to claim 1, characterized in that, The method comprises the following steps: S1, feeding nylon 6 chips from the main feeding port; S2, weighing and batching the antioxidant, whitening agent, dispersant, titanium dioxide, phthalocyanine blue and permanent purple RL pigment, and then feeding them into the buffer bin after premixing, and then spirally stirring to mix uniformly after being discharged into the hopper, and then feeding them from the side feeding port; S3, uniformly mixing the raw materials and then feeding them into the twin-screw extruder for melt mixing to obtain a whitening nylon 6 master batch melt; S4, extruding the whitening nylon 6 master batch melt strip from the outlet of the twin-screw extruder, and then feeding it into the granulator after being cooled in the water cooling tank, and then performing granulation, vibration screening and air drying to prepare the whitening nylon 6 master batch.

5. The process for the preparation of whitening masterbatch of nylon 6 as claimed in claim 4 wherein: The rotation speed of the side feeding feeding port is controlled at 500-550 r / min.

6. The process for the preparation of whitening masterbatch of nylon 6 as claimed in claim 4 wherein: The length-diameter ratio of the twin-screw extruder is 40:

1.

7. The process for the preparation of whitening masterbatch of nylon 6 as claimed in claim 4 wherein: The rotation speed of the screw of the twin-screw extruder is controlled at 500-600 r / min.

8. The process for the preparation of whitening masterbatch of nylon 6 as claimed in claim 4 wherein: The melt plasticizing process of the twin-screw extruder is divided into nine temperature zones and a die head temperature zone.

9. The process for the preparation of whitening masterbatch of nylon 6 as claimed in claim 8 wherein: The temperature of each temperature zone is controlled as follows: the first, second, third, fourth and fifth temperature zones are 220-240℃, the sixth, seventh, eighth and ninth temperature zones are 180-210℃, and the temperature of the die head is 220-240℃.

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