A Nylon Chip for Transparent Fishing Net and Its Preparation Method

Abstract

This application relates to the technical field of nylon chips, and specifically relates to a nylon chip for transparent fishing nets and its preparation method. The nylon chip for transparent fishing nets of this application contains nylon and a modifier, where the modifier is an aromatic amine antioxidant. It not only has good ultraviolet resistance, but also contains rigid structures such as benzene rings or naphthalene rings, which is beneficial to improving the tensile properties of the nylon chips. In addition, after the aromatic amine antioxidant is modified by dichloroacyl chloride and caprolactam, its compatibility with nylon is better, and it can also form more and smaller crystals, which is beneficial to improving the light transmittance of the nylon chips and reducing the haze, thereby improving the capture efficiency of the fishing nets. The preparation method of the nylon chip for transparent fishing nets of this application is to mix the modifier and nylon and then carry out melt extrusion, cooling, and slicing. By controlling the cooling rate, the light transmittance of the nylon chips can be further improved.

Description

Technical Field

[0001] The present application relates to the technical field of nylon chips, and particularly relates to a nylon chip for transparent fishing nets and a preparation method thereof. Background Art

[0002] As an important tool in fishery production, the performance of fishing nets directly affects fishing efficiency and the service life of fishing gear. Traditional fishing net materials mainly include polyethylene, polypropylene, and nylon. Among them, nylon has become one of the preferred materials for fishing nets due to its high strength, wear resistance, and corrosion resistance. However, existing nylon fishing net materials still have certain limitations in terms of transparency, ultraviolet resistance, water absorption rate, and mechanical properties.

[0003] The transparency of nylon materials is greatly affected by their crystallization behavior. Ordinary nylons, such as nylon 6 and nylon 66, are prone to forming relatively large crystal grains during processing, resulting in a decrease in material transparency. To improve the transparency of nylon, it is usually necessary to reduce the crystallinity or refine the crystal grains, but this often leads to a decrease in the ultraviolet resistance of the material.

[0004] When fishing nets with better transparency are used outdoors and are exposed to ultraviolet rays for a long time, they are prone to photooxidative degradation, resulting in the material becoming brittle and the strength decreasing. The existing nylon materials have insufficient ultraviolet resistance and are difficult to meet the requirements for long-term use. Although the performance can be improved by adding ultraviolet absorbers, conventional ultraviolet absorbers often affect the transparency and mechanical properties of the material.

[0005] At present, some technologies have attempted to improve the transparency, ultraviolet resistance, and mechanical properties of nylon materials through blending, copolymerization, or adding additives. The patent application document with publication number CN112476824A discloses a preparation method of transparent nylon, and the components included are nylon 6, nylon 6I, plasticizer, nucleating agent, antioxidant, and lubricant. During preparation, the dried nylon 6I resin is first added to a twin-screw extruder, and the plasticizer is added using a liquid metering pump for melt blending, extrusion, and pelletizing to prepare a plasticizer masterbatch. Then, nylon 6, nylon 6I, plasticizer masterbatch, nucleating agent, antioxidant, and lubricant are mixed at high speed and then subjected to melt blending, extrusion, cooling, air drying, and pelletizing in a twin-screw extruder. During the preparation process of the above transparent nylon, the nucleating agent, antioxidant, and lubricant are directly blended with the nylon resin, which may cause compatibility problems, resulting in unstable performance of the prepared transparent nylon. Summary of the Invention

[0006] In order to improve the ultraviolet resistance and performance stability of nylon chips for transparent fishing nets, the present application provides a nylon chip for transparent fishing nets and a preparation method thereof.

[0007] A nylon chip for transparent fishing net, comprising the following components in parts by weight: 70-95 parts of nylon, 5-30 parts of modifier. The preparation method of the modifier includes the following steps:

[0008] S1: Mix the aromatic amine antioxidant, diacyl chloride and toluene evenly, react at 100-120 °C for 2-5 h, add caprolactam, react for 2-5 h, extract the product and dry it under vacuum to obtain an intermediate material;

[0009] S2: Melt caprolactam, add sodium hydroxide, mix evenly, evacuate to remove bubbles, keep warm at 120-150 °C for 0.5-1 h, add the intermediate material, mix evenly, react for 1-5 h, extract, wash and dry the product under vacuum to obtain the modifier.

[0010] In the above technical solution, first, the amino group or imino group in the aromatic amine antioxidant reacts with diacyl chloride and is capped with caprolactam, and then grafts the polyamide chain segment to obtain the modifier. Adding the modifier to nylon can endow the transparent nylon with good anti-ultraviolet performance and mechanical properties.

[0011] First, the modifier contains a benzene ring or a naphthalene ring. The benzene ring or naphthalene ring is an aromatic ring structure composed of carbon and hydrogen, which has non-polarity and hydrophobicity, will reduce the polarity of the nylon molecular chain, thereby reducing the proportion of polar groups in the nylon molecular chain and reducing the formation of hydrogen bonds between polar groups and water molecules in the nylon molecule; in addition, the rigid structure of the benzene ring or naphthalene ring restricts the mobility of the nylon molecular chain, and the benzene ring or naphthalene ring fills the gaps between the nylon molecular chains, reducing the free volume, making the diffusion of water molecules difficult and the molecular chain difficult to swell, thus reducing the water absorption rate.

[0012] Second, the rigid structure of the benzene ring or naphthalene ring will restrict the mobility of the nylon molecular chain, making the nylon not easily deformed when stressed, thus improving the strength; in addition, the benzene ring or naphthalene ring forms stronger intermolecular forces through π-π stacking, thereby making the nylon stronger.

[0013] Third, the rigid structure of the benzene ring or naphthalene ring can act as a heterogeneous nucleation point during the melting and cooling process of nylon, providing additional nucleation centers, increasing the number of nucleation centers, and enabling the crystallization process to crystallize simultaneously at more nucleation centers, accelerating the crystallization rate. The faster the crystallization rate, the shorter the grain growth time, thus forming more fine grains; in addition, the rigid structure of the benzene ring or naphthalene ring fills the free volume between the nylon molecular chains, reducing the movement space of the molecular chains and restricting the growth space of the grains, making the grains unable to grow larger, so the grain size is smaller.

[0014] Fourthly, the benzene ring or naphthalene ring forms an extended conjugated system through conjugated double bonds. The conjugated system can absorb the energy of ultraviolet light and convert it into heat energy or other forms of energy through non-radiative transitions, reducing the damage of ultraviolet rays to nylon materials. Moreover, the highly stable aromatic structure of the benzene ring or naphthalene ring can capture free radicals generated under ultraviolet irradiation and prevent free radicals from initiating chain reactions, thereby resisting photooxidative degradation caused by ultraviolet rays.

[0015] In summary, after modification with the modifier, the water absorption rate of nylon decreases, the strength increases, the transparency improves, and the ultraviolet resistance performance improves.

[0016] Preferably, the nylon is one or more of nylon 6, nylon 66, and nylon 610.

[0017] Preferably, in step S1, the aromatic amine antioxidant is one or more of N-phenyl-α-naphthylamine, N,N'-bis(2-naphthyl)-1,4-phenylenediamine, and N,N'-diphenyl-p-phenylenediamine

[0018] In the above technical solution, the aromatic amine antioxidant has an aromatic structure with a benzene ring or naphthalene ring, which can capture free radicals generated under ultraviolet irradiation, prevent free radicals from initiating chain reactions, and can convert the absorbed ultraviolet energy into other energy, thereby reducing the damage of ultraviolet rays to nylon materials.

[0019] Preferably, in step S1, the diacyl chloride is one of adipoyl chloride, sebacoyl chloride, terephthaloyl chloride, and isophthaloyl chloride.

[0020] Preferably, in step S1, the mass ratio of the aromatic amine antioxidant, adipoyl chloride, and caprolactam is 1:(1.2 - 2):(1 - 1.2).

[0021] Preferably, in step S2, the mass ratio of caprolactam to sodium hydroxide is 100:(0.2 - 0.5).

[0022] Preferably, in step S2, the mass ratio of caprolactam to the intermediate material is 100:(5 - 20).

[0023] By adopting the above technical solution, grafting the polyamide chain segment onto the molecule of the intermediate material enables the modifier to contain more groups and chain segments highly similar to nylon, which can enhance the compatibility between the modifier and nylon and improve the stability of nylon performance. Moreover, the amide groups in the modifier and the amide groups in nylon can further strengthen the compatibility between the modifier and nylon through hydrogen bond interactions.

[0024] A preparation method of nylon chips for transparent fishing nets includes the following steps:

[0025] After uniformly mixing the modifier with polyamide, extrude it with a twin-screw extruder, slice it after cooling, and that's it.

[0026] In the above technical solution, the modifier and polyamide have good compatibility. After they are uniformly mixed, they are extruded through a twin-screw extruder, and fine grains are formed during the cooling process, thereby improving the transparency of polyamide.

[0027] Preferably, the twin-screw extrusion temperatures are 200 - 220 °C, 210 - 230 °C, 220 - 245 °C, 220 - 245 °C, 220 - 245 °C, 210 - 230 °C in sequence, and the screw rotation speed is 200 - 400 r / min.

[0028] Preferably, the cooling rate is 5 - 20 °C / min.

[0029] In the above technical solution, the cooling rate has an important influence on the size and crystallinity of the formed grains. When the cooling rate is small, the temperature drops slowly, the temperature holding time is long, the activity ability of the polyamide molecular chain is strong, and there is a long activity time to complete the regular arrangement and grain growth. Therefore, the crystallinity will increase and the grain volume will become larger. When the cooling rate increases, the temperature drops quickly, the polyamide molecular chain has a short time for high-temperature crystallization, and the activity ability of the molecular chain decreases significantly in a short time. Therefore, the crystallinity decreases, the grains do not have time to grow, and the grains are small. When the crystallinity is low and the grains are small, the transparency of polyamide will increase.

[0030] The above technical solution of this application has at least the following beneficial effects:

[0031] 1. In this application, an aromatic amine antioxidant with good ultraviolet resistance is grafted onto the polyamide chain segment to improve the compatibility between the modifier and polyamide, thereby improving the performance stability of polyamide;

[0032] 2. The aromatic amine antioxidant in the modifier of this application not only has good ultraviolet resistance, but also can be used as a heterogeneous nucleating agent to refine grains during the crystallization process of polyamide and improve the transparency of polyamide;

[0033] 3. The introduction of the modifier in this application is beneficial to reducing the water absorption rate of polyamide, improving the mechanical properties of polyamide, etc., enhancing the dimensional stability of the fishing net, and reducing the fishing burden. Description of the Drawings

[0034] Figure 1 is the change in tensile strength of polyamide chips for transparent fishing nets before and after ultraviolet irradiation;

[0035] Figure 2 is the light transmittance and haze of polyamide chips for transparent fishing nets;

[0036] Figure 3 It is the curve of the total crystallization time of nylon chips for transparent fishing nets varying with the cooling rate;

[0037] Figure 4 It is the curve of the crystallization onset temperature of nylon chips for transparent fishing nets varying with the cooling rate. Specific embodiments

[0038] The following further elaborates on this application in conjunction with examples.

[0039] The raw materials of the examples and comparative examples of this application are all ordinary commercially available products unless otherwise specified.

[0040] Examples

[0041] Example 1

[0042] The nylon chips for transparent fishing nets in this example are composed of the following components in parts by weight: 50 parts of nylon 6, 45 parts of nylon 66, and 5 parts of a modifier;

[0043] The preparation method of the modifier in this example includes the following steps:

[0044] S1: Weigh 10 g of N-phenyl-α-naphthylamine and place it in a three-necked flask. Add 12 g of terephthaloyl chloride and 30 mL of toluene, mix evenly, and heat and react in an oil bath at 100 °C for 5 h. Add 10 g of caprolactam and continue to react for 5 h. The product is extracted with toluene for 24 h, and then dried in a vacuum drying oven at 120 °C for 6 h to obtain an intermediate material;

[0045] S2: Weigh 500 g of caprolactam and place it in a flask. Melt it in an oil bath at 110 °C, add 1 g of sodium hydroxide, mix evenly, evacuate to no bubbles, and raise the temperature to 120 °C, keep warm for 1 h. Then add 25 g of the intermediate material, quickly shake to mix evenly, react for 5 h. The reaction product is placed in a Soxhlet extractor, extracted with formic acid for 24 h, washed with distilled water until neutral, and dried to a constant weight under vacuum, then it is ready;

[0046] The preparation method of the nylon chips for transparent fishing nets in this example includes the following steps:

[0047] Weigh 500 g of nylon 6, 450 g of nylon 66, and 50 g of the modifier, mix evenly with a high-speed kneader, extrude with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 200 °C, 210 °C, 220 °C, 220 °C, 220 °C, 210 °C respectively, the screw speed is 400 r / min. After the extrudate is cooled to room temperature at a speed of 5 °C / min, it is sliced, then it is ready.

[0048] Example 2

[0049] The nylon chips for transparent fishing nets in this embodiment are composed of the following components in parts by weight: 50 parts of nylon 6, 45 parts of nylon 66, and 5 parts of modifier;

[0050] The preparation method of the modifier in this embodiment includes the following steps:

[0051] S1: Weigh 10 g of N,N'-diphenyl-p-phenylenediamine and place it in a three-necked flask. Add 20 g of N,N'-diphenyl-p-phenylenediamine and 30 mL of toluene, mix evenly, and heat and react in an oil bath at 120 °C for 2 h. Then add 12 g of caprolactam and continue to react for 2 h. Extract the product with toluene for 24 h, and then dry it in a vacuum drying oven at 120 °C for 6 h to obtain an intermediate material;

[0052] S2: Weigh 500 g of caprolactam and place it in a flask. Melt it in an oil bath at 110 °C, add 2.5 g of sodium hydroxide, mix evenly, evacuate to no bubbles, and then raise the temperature to 150 °C and keep it warm for 0.5 h. Then add 25 g of the intermediate material, quickly shake to mix evenly, react for 1 h, place the reaction product in a Soxhlet extractor, extract with formic acid for 24 h, wash with distilled water until neutral, and dry to constant weight under vacuum, then it is ready;

[0053] The preparation method of the nylon chips for transparent fishing nets in this embodiment includes the following steps:

[0054] Weigh 500 g of nylon 6, 450 g of nylon 66, and 50 g of modifier, mix them evenly with a high-speed kneader, and extrude them with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 220 °C, 230 °C, 245 °C, 245 °C, 245 °C, and 230 °C respectively, the screw speed is 200 r / min, and after the extrudate is cooled to room temperature at a rate of 5 °C / min, it is sliced, then it is ready.

[0055] Example 3

[0056] The nylon chips for transparent fishing nets in this embodiment are composed of the following components in parts by weight: 50 parts of nylon 6, 45 parts of nylon 66, and 5 parts of modifier;

[0057] The preparation method of the modifier in this embodiment includes the following steps:

[0058] S1: Weigh 10 g of N,N'-diphenyl-p-phenylenediamine and place it in a three-necked flask. Add 16 g of N,N'-bis(2-naphthyl)-1,4-phenylenediamine and 30 mL of toluene, mix evenly, and heat and react in an oil bath at 110 °C for 3 h. Then add 12 g of caprolactam and continue to react for 3 h. Extract the product with toluene for 24 h, and then dry it in a vacuum drying oven at 120 °C for 6 h to obtain an intermediate material;

[0059] S2: Weigh 500 g of caprolactam and place it in a flask. Melt it in an oil bath at 110 °C, add 1.5 g of sodium hydroxide, mix evenly, evacuate to no bubbles, then raise the temperature to 130 °C, hold for 0.5 h, then add 25 g of intermediate material, quickly shake to mix evenly, react for 3 h, place the reaction product in a Soxhlet extractor, extract with formic acid for 24 h, wash with distilled water until neutral, and dry in vacuum to constant weight, then it is ready;

[0060] The preparation method of the nylon chips for transparent fishing nets in this example includes the following steps:

[0061] Weigh 500 g of nylon 6, 450 g of nylon 66 and 50 g of modifier, mix evenly with a high-speed kneader, extrude with a twin-screw extruder, the six-section extrusion temperatures of the twin-screw extruder are 210 °C, 220 °C, 240 °C, 245 °C, 240 °C, 220 °C respectively, the screw speed is 300 r / min, and the extrudate is cooled to room temperature at a speed of 5 °C / min and then sliced, then it is ready.

[0062] Example 4

[0063] The weight part components of the nylon chips for transparent fishing nets in this example are the same as those in Example 3;

[0064] The difference in the preparation method of the modifier in this example from that in Example 3 lies in:

[0065] S2: Weigh 500 g of caprolactam and place it in a flask. Melt it in an oil bath at 110 °C, add 1.5 g of sodium hydroxide, mix evenly, evacuate to no bubbles, then raise the temperature to 130 °C, hold for 0.5 h, then add 100 g of intermediate material, quickly shake to mix evenly, react for 3 h, place the reaction product in a Soxhlet extractor, extract with formic acid for 24 h, wash with distilled water until neutral, and dry in vacuum to constant weight, then it is ready;

[0066] The remaining steps are the same as those in Example 3;

[0067] The preparation method of the nylon chips for transparent fishing nets in this example is the same as that in Example 3.

[0068] Example 5

[0069] The weight part components of the nylon chips for transparent fishing nets in this example are the same as those in Example 3;

[0070] The difference in the preparation method of the modifier in this example from that in Example 3 lies in:

[0071] S2: Weigh 500 g of caprolactam and place it in a flask. Melt it in an oil bath at 110 °C, add 1.5 g of sodium hydroxide, mix evenly, evacuate until there are no bubbles, then raise the temperature to 130 °C and keep it warm for 0.5 h. Then add 75 g of intermediate material, quickly shake to mix evenly, react for 3 h, place the reaction product in a Soxhlet extractor, extract with formic acid for 24 h, wash with distilled water until neutral, and dry in vacuum until constant weight, then it is ready;

[0072] The remaining steps are the same as those in Example 3;

[0073] The preparation method of the nylon chips for transparent fishing nets in this example is the same as that in Example 3.

[0074] Example 6

[0075] The nylon chips for transparent fishing nets in this example are composed of the following components in parts by weight: 70 parts of nylon 610 and 30 parts of modifier;

[0076] The preparation method of the modifier in this example is the same as that in Example 5;

[0077] The preparation method of the nylon chips for transparent fishing nets in this example includes the following steps:

[0078] Weigh 700 g of nylon 610 and 300 g of modifier, mix evenly with a high-speed kneader, extrude with a twin-screw extruder, and the six-section extrusion temperatures of the twin-screw extruder are 210 °C, 220 °C, 240 °C, 245 °C, 240 °C, and 220 °C respectively, the screw speed is 300 r / min, and after the extrudate is cooled to room temperature at a speed of 5 °C / min, it is sliced, then it is ready.

[0079] Example 7

[0080] The nylon chips for transparent fishing nets in this example are composed of the following components in parts by weight: 50 parts of nylon 66, 30 parts of nylon 610, and 20 parts of modifier;

[0081] The preparation method of the modifier in this example is the same as that in Example 5;

[0082] The preparation method of the nylon chips for transparent fishing nets in this example includes the following steps:

[0083] Weigh 500 g of nylon 66, 300 g of nylon 610, and 200 g of modifier, mix evenly with a high-speed kneader, extrude with a twin-screw extruder, and the six-section extrusion temperatures of the twin-screw extruder are 210 °C, 220 °C, 240 °C, 245 °C, 240 °C, and 220 °C respectively, the screw speed is 300 r / min, and after the extrudate is cooled to room temperature at a speed of 5 °C / min, it is sliced, then it is ready.

[0084] Example 8

[0085] The weight parts of the components of the nylon chips for the transparent fishing net in this embodiment are the same as those in Embodiment 7;

[0086] The preparation method of the modifier in this embodiment is the same as that in Embodiment 7;

[0087] The preparation method of the nylon chips for the transparent fishing net in this embodiment includes the following steps:

[0088] Weigh 500 g of nylon 66, 300 g of nylon 610 and 200 g of the modifier, mix them evenly with a high-speed kneader, and extrude them with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 210°C, 220°C, 240°C, 245°C, 240°C, and 220°C respectively, the screw speed is 300 r / min, and the extrudate is cooled to room temperature at a speed of 20°C / min and then sliced.

[0089] Embodiment 9

[0090] The weight parts of the components of the nylon chips for the transparent fishing net in this embodiment are the same as those in Embodiment 7;

[0091] The preparation method of the modifier in this embodiment is the same as that in Embodiment 7;

[0092] The preparation method of the nylon chips for the transparent fishing net in this embodiment includes the following steps:

[0093] Weigh 500 g of nylon 66, 300 g of nylon 610 and 200 g of the modifier, mix them evenly with a high-speed kneader, and extrude them with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 210°C, 220°C, 240°C, 245°C, 240°C, and 220°C respectively, the screw speed is 300 r / min, and the extrudate is cooled to room temperature at a speed of 15°C / min and then sliced.

[0094] Comparative Example

[0095] Comparative Example 1

[0096] The nylon chips for the transparent fishing net in this comparative example are composed of the following components in weight parts: 50 parts of nylon 6 and 50 parts of nylon 66;

[0097] The preparation method of the nylon chips for the transparent fishing net in this comparative example includes the following steps:

[0098] Weigh 500 g of nylon 6 and 500 g of nylon 66, mix them evenly with a high-speed kneader, and extrude them with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 200°C, 210°C, 220°C, 220°C, 220°C, and 210°C respectively, the screw speed is 400 r / min, and the extrudate is cooled to room temperature at a speed of 5°C / min and then sliced.

[0099] Comparative Example 2

[0100] The nylon chips for transparent fishing nets in this comparative example are composed of the following components in parts by weight: 50 parts of nylon 6, 45 parts of nylon 66, and 5 parts of N-phenyl-α-naphthylamine;

[0101] The preparation method of the nylon chips for transparent fishing nets in this comparative example includes the following steps:

[0102] Weigh 500 g of nylon 6, 450 g of nylon 66, and 50 g of N-phenyl-α-naphthylamine, mix them evenly with a high-speed kneader, and extrude them with a twin-screw extruder. The six-section extrusion temperatures of the twin-screw extruder are 200 °C, 210 °C, 220 °C, 220 °C, 220 °C, and 210 °C respectively, the screw speed is 400 r / min, and the extrudate is cooled to room temperature at a speed of 5 °C / min and then sliced, and that's it.

[0103] Performance detection test

[0104] Specimen preparation: Add the nylon chips for transparent fishing nets in Examples 1-9 and Comparative Examples 1-2 to an injection molding machine to make standard test bars and circular specimens, and conduct mechanical property tests and optical property tests after standing for 24 h; Injection molding machine temperature: 230 °C, 240 °C, 245 °C; Injection speed: 50 g / s; Injection time: 8 s; Injection pressure: 25 MPa, holding pressure: 37 MPa, holding time: 30 s.

[0105] 1. Tensile property detection

[0106] Referring to the standard GB / T1040-92 "Test Method for Tensile Properties of Plastics", use a universal testing machine to test the tensile strength, with a tensile rate of 5 mm / min, a span of 40 mm, 5 test bars in each group of tensile specimens, take the average value, and the test results are as Figure 1 shown.

[0107] 2. UV resistance detection

[0108] Use a spherical mercury xenon lamp with an ultraviolet radiation wavelength less than 365 nm to irradiate the above standard test bars for 15 days respectively and then conduct tensile strength tests. The test results are as Figure 1 shown.

[0109] 3. Transmittance detection

[0110] Referring to the standard GB2410-80, measure the transmittance and haze of the circular specimens on a WGT-S type transmittance / haze meter. The specimen size is φ50 mm × 2.5 mm, and the test results are as Figure 2 shown.

[0111] 4. Crystallization property

[0112] Using an American DuPont SDT Q600 calorimeter, in a nitrogen atmosphere, the temperature was raised from room temperature to 250 °C at a heating rate of 80 °C / min and held for 10 min to eliminate the thermal history. Then, crystallization was carried out at cooling rates of 5 °C / min, 10 °C / min, 15 °C / min, and 20 °C / min until the temperature reached 50 °C, and it was held for 10 min. The curves of the total crystallization time and the crystallization onset temperature of the nylon chips for transparent fishing nets in Examples 3, 7 - 9 and Comparative Examples 1 - 2 changing with the cooling rate were measured, as Figure 3 and Figure 4 shown.

[0113] Result analysis

[0114] From Figure 1 the data of Comparative Examples 1 - 2 and Examples 1 - 3, it can be seen that the nylon chips for transparent fishing nets obtained through the examples have better tensile strength, and after ultraviolet irradiation, the change rate of the tensile strength is smaller, indicating better ultraviolet resistance performance; by comparing the data of Examples 3 - 7, it can be seen that increasing the addition amount of the modifier within a certain range is beneficial to improving the tensile strength and anti-ultraviolet performance of the nylon chips for transparent fishing nets. This may be because the modifier has good anti-ultraviolet performance and a rigid structure, which is beneficial to improving the tensile strength; by comparing the data of Examples 7 - 9, it can be seen that with the increase of the cooling rate, the tensile strength increases until it basically remains unchanged. This may be because after the cooling rate increases, the crystallization rate increases and the crystal grains are refined.

[0115] From Figure 2 it can be seen that compared with the comparative examples, the nylon chips for fishing nets obtained through the examples have higher light transmittance and lower haze. This may be because the addition of the modifier plays a role in heterogeneous nucleation, improving the crystallization rate and refining the crystal grains; moreover, as the addition amount of the modifier increases, the number of heterogeneous nucleation sites increases, the number of crystal grains increases, the crystal grains become smaller, and the light transmittance also increases accordingly; in addition, the increase of the cooling rate is beneficial to the increase of the crystallization rate, so that the crystal grains are formed faster, and therefore it is also beneficial to the increase of the light transmittance.

[0116] Combined with Figure 3 and Figure 4It can be seen from the data that as the cooling rate increases, both the overall crystallization time and the initial crystallization temperature of the nylon chips for fishing nets show a downward trend, indicating that with the increase of the cooling rate, crystallization occurs faster and it is easier to form crystal grains. This may be because when the cooling rate is small, the temperature drops slowly, remains at a certain temperature for a long time, the molecular chain has strong mobility, and there is enough time for regular arrangement. Therefore, the crystallization temperature is high, and the formed crystal grains have more time to grow, resulting in a longer total crystallization time. When the cooling rate is large, the temperature drops rapidly, the molecular chain stays at a high temperature for a short time, the mobility of the molecular chain decreases within a short time, and the molecular chain does not have enough time to arrange more regularly. Therefore, the crystallization temperature is low, the formed crystal grains do not have time to grow, and the total crystallization time is short. During the preparation of nylon chips for transparent fishing nets, when the addition amount of the modifier is large or the cooling rate is fast, it is conducive to the formation of more and smaller crystal grains. Therefore, the crystallization temperature decreases and the total crystallization time shortens.

[0117] This specific embodiment is only an explanation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A nylon chip for transparent fishing net, characterized in that, It comprises the following components in parts by weight: 70 - 95 parts of polyamide, 5 - 30 parts of modifier, the polyamide being one or more of polyamide 6, polyamide 66 and polyamide 610, and the preparation method of the modifier comprises the following steps: S1: Mix an aromatic amine antioxidant, a diacyl chloride and toluene evenly, react at 100 - 120 °C for 2 - 5 h, add caprolactam, react for 2 - 5 h, extract the product and dry it under vacuum to obtain an intermediate; the aromatic amine antioxidant is one or more of N - phenyl - α - naphthylamine, N,N'-bis(2 - naphthyl)-1,4 - phenylenediamine and N,N'-diphenyl - p - phenylenediamine; the diacyl chloride is one of adipoyl chloride, sebacoyl chloride, terephthaloyl chloride and isophthaloyl chloride; S2: Melt caprolactam, add sodium hydroxide, mix evenly, evacuate to remove bubbles, keep warm at 120 - 150 °C for 0.5 - 1 h, add the intermediate, mix evenly, react for 1 - 5 h, extract, wash and dry the product under vacuum to obtain the modifier.

2. The nylon chips for transparent fishing nets according to claim 1, wherein, In step S1, the mass ratio of the aromatic amine antioxidant, the diacyl chloride and caprolactam is 1:(1.2 - 2):(1 - 1.2).

3. The nylon chips for transparent fishing nets according to claim 1, characterized in that, In step S2, the mass ratio of caprolactam to sodium hydroxide is 100:(0.2 - 0.5).

4. The nylon chip for transparent fishing net according to claim 1, characterized in that, In step S2, the mass ratio of caprolactam to the intermediate is 100:(5 - 20).

5. A preparation method of nylon chips for transparent fishing nets according to claim 1, characterized in that, It comprises the following steps: Mix the modifier and polyamide evenly, extrude with a twin - screw extruder, cool and slice to obtain the product.

6. The preparation method of the nylon chip for transparent fishing net according to claim 5, wherein, The twin - screw extrusion temperatures are 200 - 220 °C, 210 - 230 °C, 220 - 245 °C, 220 - 245 °C, 220 - 245 °C, 210 - 230 °C in sequence, and the screw rotation speed is 200 - 400 r / min.

7. The preparation method of the nylon chip for transparent fishing net according to claim 5, characterized in that, The cooling rate is 5 - 20 °C / min.

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