Modified casting nylon wheel and preparation process thereof

Abstract

The invention discloses a modified casting nylon wheel and a preparation process thereof.The modified casting nylon wheel is prepared from caprolactam monomers, first ionic liquid, modified montmorillonite, a catalyst and a cocatalyst, the modified montmorillonite comprises a montmorillonite body and second ionic liquid, the interface bonding strength of the montmorillonite and a nylon matrix is improved, and the bonding strength of the montmorillonite and the nylon matrix is improved; the load transmission efficiency is improved, the creep deformation rate is remarkably delayed, the water molecule permeation path is prolonged by the modified montmorillonite, the montmorillonite treated by the second ionic liquid forms a nanoscale layered structure and is uniformly dispersed in a nylon matrix, a compact'labyrinth effect 'is constructed, the hygroscopicity is reduced, the ionic liquid promotes formation of chemical bonds among molecular chains in polymerization, and the creep deformation rate is improved. And a three-dimensional network structure is constructed, so that the creep resistance is improved, and the defect of size expansion caused by overhigh hygroscopicity and poor creep resistance in the use process of the nylon wheel of the port crane in the prior art is overcome.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a modified cast nylon wheel and a preparation process thereof. Background Art

[0002] Port cranes are core equipment for operations in ports, docks and other waters, and are specifically used for cargo loading and unloading, ship berthing and yard management. Nylon pulleys are used for wire rope guidance and load bearing, replacing traditional steel pulleys, reducing wire rope wear and extending service life.

[0003] When the nylon wheels of port cranes are continuously overloaded, they will creep and expand radially, which will increase the gap with the rails or wire ropes and cause vibration or abnormal wear. The nylon material itself has good hygroscopicity. After absorbing water, the nylon will further expand in size, which will increase the gap with the rails or wire ropes and increase the risk of vibration and eccentric wear.

[0004] Therefore, it is necessary to improve the modified cast nylon wheel in the prior art to solve the above problems. Summary of the invention

[0005] The present invention overcomes the shortcomings of the prior art and provides a modified cast nylon wheel and a preparation process thereof, aiming to solve the defects of dimensional expansion caused by excessively high hygroscopicity and poor creep resistance of the nylon wheel of a port crane in the prior art during use.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a modified cast nylon wheel, wherein the modified cast nylon wheel raw material comprises, by weight: 80-120 parts of caprolactam monomer, 8-12 parts of a first ionic liquid, 2-4 parts of modified montmorillonite, 0.1-1 parts of a catalyst and 0.1-1 parts of a co-catalyst; The first ionic liquid is a pyridine ionic liquid, the modified montmorillonite includes a montmorillonite body and a second ionic liquid, the montmorillonite body is one of sodium-based montmorillonite and calcium-based montmorillonite, and the second ionic liquid is an imidazole ionic liquid.

[0007] In a preferred embodiment of the present invention, the raw material mass ratio of the montmorillonite body and the second ionic liquid in the modified montmorillonite is 80-95:5-20.

[0008] In a preferred embodiment of the present invention, the structural formula of the first ionic liquid is:

[0009] Wherein R1 and R2 are one of methyl, ethyl, butyl and acetoxy, respectively, and X - It is one of the chloride ion, bromide ion and boron tetrafluoride ion.

[0010] In a preferred embodiment of the present invention, the structural formula of the second ionic liquid is:

[0011] wherein R is C n H 2n SO3H (n is an integer, 1 ≤ n ≤ 4), and Y - is one of chloride ion, bromide ion, iodide ion, and acetate ion.

[0012] In a preferred embodiment of the present invention, the catalyst is one of sodium hydroxide, potassium hydroxide, and sodium carbonate, and the co-catalyst is isocyanate.

[0013] To achieve the above object, the second technical solution adopted by the present invention is: a preparation process of a modified cast nylon wheel, comprising the following steps: S1: Mix the montmorillonite body and the second ionic liquid in water, stir at 60 - 70 °C for 3 - 4 h, separate and dry, and then grind to obtain modified montmorillonite; S2: Put the caprolactam monomer and the modified montmorillonite in S1 into a reaction kettle, and the temperature when putting it into the reaction kettle is 70 - 85 °C, and stir for 0.5 - 2 h; S3: Add the catalyst and the co-catalyst into the reaction kettle, control the pressure in the reaction kettle to be 0.05 - 0.1 MPa, vacuum dehydrate for 15 - 30 min, add the first ionic liquid, control the temperature to be 135 - 150 °C, and continue to react for 0.5 - 2 h; S4: Put the substances in the reaction kettle into a nylon wheel mold and centrifuge, take out and cool and solidify to obtain a modified cast nylon wheel.

[0014] In a preferred embodiment of the present invention, the mass ratio between the total mass of the montmorillonite body and the second ionic liquid and water is 1:5 - 10.

[0015] In a preferred embodiment of the present invention, the grinding process parameters in S1 are: the grinding speed is 300 - 500 r / min, and the grinding time is 20 - 40 min.

[0016] In a preferred embodiment of the present invention, the centrifugal speed in S4 is 200 - 400 rpm.

[0017] In a preferred embodiment of the present invention, the centrifugal time in S4 is 2 - 4 min.

[0018] The present invention solves the defects existing in the background technology, and the present invention has the following beneficial effects: (1) The present invention provides a modified cast nylon wheel. The raw materials of the modified cast nylon wheel include: caprolactam monomer, a first ionic liquid, modified montmorillonite, a catalyst, and a cocatalyst. The modified montmorillonite includes a montmorillonite body and a second ionic liquid. The interfacial bonding strength between the montmorillonite and the nylon matrix is improved, the load transfer efficiency is enhanced, the creep deformation rate is significantly delayed, and the modified montmorillonite extends the water molecule penetration path. Compared with the nylon wheel in the prior art, the montmorillonite treated with the second ionic liquid forms a nanoscale layered structure, which is uniformly dispersed in the nylon matrix to construct a dense "labyrinth effect", reducing the hygroscopicity. The ionic liquid promotes the formation of chemical bonds between molecular chains during polymerization to construct a three-dimensional network structure, improving the anti-creep performance, and solving the defect of dimensional expansion caused by excessive hygroscopicity and poor anti-creep performance during the use of the nylon wheel of port cranes in the prior art.

[0019] (2) In the present invention, the intercalation polymerization method is adopted between the montmorillonite and the nylon matrix. The intercalation polymerization enables the nylon polymer chains to enter the interlayer of the montmorillonite, enhancing the interfacial interaction between the two, effectively preventing the chain segment sliding of the matrix when stressed, and improving the tensile strength and flexural modulus of the material. Compared with the prior art, the montmorillonite nanosheets can play a role in stress concentration and dispersion in the matrix. When the material is subjected to an external force impact, the matrix around the nanosheets can absorb and dissipate more energy, thereby improving the impact toughness and elongation at break of the material.

[0020] (3) In the present invention, the imidazole-based ionic liquid modifies the montmorillonite through ion exchange. Its carbon chain inserts into the interlayer of the montmorillonite and covers the surface to form a hydrophobic microenvironment. Compared with the prior art, the layered structure of the montmorillonite can physically block the penetration of moisture, and at the same time, the hydrophobic groups of the ionic liquid reduce the contact opportunity between the amide bonds in the nylon and water, reducing the overall hygroscopicity. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings; Figure 1 It is a method step diagram of a preferred embodiment of the present invention. Detailed Embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0024] A modified cast nylon wheel, the raw materials of the modified cast nylon wheel include, by mass parts: 80 - 120 parts of caprolactam monomer, 8 - 12 parts of a first ionic liquid, 2 - 4 parts of modified montmorillonite, 0.1 - 1 part of a catalyst, and 0.1 - 1 part of a cocatalyst; The first ionic liquid is a pyridine-based ionic liquid. The modified montmorillonite includes a montmorillonite body and a second ionic liquid. The montmorillonite body is one of sodium-based montmorillonite and calcium-based montmorillonite, and the second ionic liquid is an imidazole-based ionic liquid.

[0025] A modified cast nylon wheel, the raw materials of the modified cast nylon wheel include: caprolactam monomer, a first ionic liquid, modified montmorillonite, a catalyst, and a cocatalyst. The modified montmorillonite includes a montmorillonite body and a second ionic liquid. The interfacial bonding strength between the montmorillonite and the nylon matrix is improved, the load transfer efficiency is enhanced, the creep deformation rate is significantly delayed, and the modified montmorillonite extends the water molecule penetration path. The montmorillonite treated with the second ionic liquid forms a nanoscale layered structure and is uniformly dispersed in the nylon matrix to construct a dense "labyrinth effect", reducing the hygroscopicity. The ionic liquid promotes the formation of chemical bonds between molecular chains during polymerization, constructs a three-dimensional network structure, and improves the anti-creep performance, solving the defect of dimensional expansion caused by excessive hygroscopicity and poor anti-creep performance during the use of nylon wheels of port cranes in the prior art.

[0026] The strong hygroscopicity of nylon stems from the hydrogen bond formed between the polar amide bonds in the molecule and water molecules. After absorbing water, it is easy to cause dimensional expansion and a decrease in mechanical properties. Imidazole-based ionic liquids can modify montmorillonite through ion exchange. Its carbon chain inserts into the interlayer of montmorillonite and covers the surface to form a hydrophobic microenvironment. When this organophilic montmorillonite is dispersed in the nylon matrix, the layered structure of montmorillonite can physically block the penetration of water, and at the same time, the hydrophobic groups of the ionic liquid reduce the contact opportunity between the amide bonds in nylon and water, reducing the overall hygroscopicity.

[0027] Pyridine-based ionic liquids have long hydrophobic carbon chains. These hydrophobic groups can act together with the hydrophobic groups of imidazole-based ionic liquids to further enhance the hydrophobicity between and on the surface of montmorillonite layers. The increase in hydrophobic groups makes it more difficult for water molecules to approach and penetrate the montmorillonite layers, thereby reducing the hygroscopicity of the nylon matrix. The hydrophobic groups of these two ionic liquids can form a denser and more uniform hydrophobic layer on the surface of montmorillonite, effectively preventing water molecules from contacting montmorillonite and the nylon matrix. This synergistic effect makes the hydrophobic microenvironment more stable and effective, further reducing the chance of water molecule intrusion.

[0028] The mass ratio of the montmorillonite body to the second ionic liquid in the modified montmorillonite is 80 - 95:5 - 20. Within this mass ratio range, the montmorillonite treated with the second ionic liquid can form a nanoscale layered structure and can be evenly dispersed in the nylon matrix, capable of constructing a denser "labyrinth effect", making the penetration path of water molecules inside the nylon wheel extremely tortuous and long, thereby effectively reducing the water molecule adsorption capacity of the nylon wheel and reducing the dimensional changes caused by moisture absorption.

[0029] When the dosages of the montmorillonite body and the second ionic liquid are within this ratio range, it can not only ensure good dispersibility of the modified montmorillonite in the nylon matrix but also ensure the integrity of the barrier structure formed. If there is too much montmorillonite body and too little second ionic liquid, a nanoscale layered structure cannot be fully formed, and the barrier effect is poor; conversely, if there is too little montmorillonite body and too much second ionic liquid, problems such as agglomeration will occur, affecting uniform dispersion, and it is also not conducive to constructing a good labyrinth structure to block water molecules.

[0030] At this mass ratio, the interfacial bonding strength between the montmorillonite body and the nylon matrix is improved, and the load transfer efficiency is enhanced. This enables the internal stress of the nylon wheel to be more evenly distributed when bearing the long-term load during the operation of the port crane, reducing the deformation caused by local stress concentration, thereby delaying the creep deformation rate and reducing the dimensional expansion caused by poor anti-creep performance.

[0031] In this ratio range, the second ionic liquid can better interact with the montmorillonite body and, at the same time, synergistically interact with the first ionic liquid and the molecules in the nylon matrix during the polymerization process to more effectively promote the formation of chemical bonds between molecular chains, thereby constructing a three-dimensional network structure. This three-dimensional network structure enhances the overall stability and rigidity of the nylon wheel, improves the anti-creep performance, and helps to solve the problem of dimensional expansion.

[0032] The structural formula of the first ionic liquid is:

[0033] wherein R1 and R2 are each one of methyl, ethyl, butyl, and acetate group, X- is one of chloride ion, bromide ion, and tetrafluoroborate ion. Different combinations of R1 and R2 and the selection of X - can adjust the interaction between the first ionic liquid, nylon matrix, and modified montmorillonite. A suitable ionic liquid can better be compatible with the nylon matrix and improve the dispersion of modified montmorillonite in the nylon matrix, making the "labyrinth effect" more obvious and the water molecule penetration path more tortuous and complex, further reducing the hygroscopicity.

[0034] During the polymerization process, the presence of the first ionic liquid can promote the formation of chemical bonds between molecular chains and construct a three-dimensional network structure. Different groups of R1 and R2 and X - 's selection will affect its interaction mode and strength with nylon molecular chains. A suitable ionic liquid can more effectively promote the crosslinking between nylon molecular chains, make the network structure denser, thereby improving the creep resistance of the nylon wheel, delaying the creep deformation rate, and reducing the size expansion caused by poor creep resistance.

[0035] By adjusting R1, R2, and X - , the first ionic liquid can enhance the interfacial bonding strength between the montmorillonite body and the nylon matrix. Good interfacial bonding helps improve the load transfer efficiency, so that when the nylon wheel bears a load, the stress can be more evenly distributed between the matrix and montmorillonite, avoiding deformation caused by local stress concentration, thereby improving the creep resistance and reducing the possibility of size expansion.

[0036] The structural formula of the second ionic liquid is:

[0037] where R is C n H 2n SO3H (n is an integer, 1 ≤ n ≤ 4), and Y - is one of chloride ion, bromide ion, iodide ion, and acetate ion. The R group has certain hydrophobicity. After binding to the montmorillonite body, it can enhance the overall hydrophobicity of the modified montmorillonite. When Y - is chloride ion, bromide ion, iodide ion, or acetate ion, these anions are paired with the R group, further enhancing the hydrophobic ability of the modified montmorillonite, effectively delaying the water molecule penetration path in the nylon wheel, reducing the hygroscopicity, and reducing the size expansion caused by moisture absorption.

[0038] Under the combination of suitable R and Y - , the second ionic liquid can improve the dispersion of the montmorillonite body in the nylon matrix. Good dispersion helps construct a denser and more uniform "labyrinth effect", making it more difficult for water molecules to invade the interior of the nylon wheel. At the same time, it is also beneficial to improve the interaction between montmorillonite and the matrix, creating conditions for enhancing the creep resistance.

[0039] During the polymerization reaction, R and Y of the second ionic liquid - structures help promote the formation of chemical bonds between nylon molecular chains and construct a three-dimensional network structure. This enhances the overall strength and rigidity of the nylon wheel, making it less prone to creep deformation when bearing loads, thereby delaying dimensional expansion.

[0040] Suitable R and Y - combinations can enhance the interfacial bonding strength between the montmorillonite matrix and the nylon matrix. Good interfacial bonding can improve the load transfer efficiency, making the stress distribution in the nylon wheel more uniform during use, reducing deformation caused by local stress concentration, enhancing the creep resistance performance, and reducing the risk of dimensional expansion.

[0041] The catalyst is one of sodium hydroxide, potassium hydroxide, and sodium carbonate, and the co-catalyst is isocyanate. These catalysts such as sodium hydroxide, potassium hydroxide, and sodium carbonate have strong alkalinity and can effectively catalyze the polymerization reaction of caprolactam monomers, accelerating the reaction rate and enabling the monomers to be converted into nylon polymers more quickly.

[0042] As a co-catalyst, isocyanate can react with active groups such as terminal hydroxyl groups in the nylon polymer to form a cross-linked structure. This cross-linked structure can increase the rigidity and strength of the nylon wheel, making it less prone to creep deformation when subjected to long-term loads, effectively solving the problem of dimensional expansion caused by poor creep resistance performance.

[0043] The catalyst and the co-catalyst act synergistically to promote the formation of more chemical bonds between the nylon polymer molecular chains and construct a more compact three-dimensional network structure. This not only improves the overall stability and anti-deformation ability of the nylon wheel but also optimizes the stress distribution inside the material, enabling the nylon wheel to better withstand various loads and stresses under the complex working conditions of port cranes and reducing creep deformation caused by factors such as stress concentration.

[0044] As Figure 1 shown, a preparation process for a modified cast nylon wheel includes the following steps: S1: Mix the montmorillonite matrix and the second ionic liquid in water and stir for 3 - 4 h in an environment of 60 - 70 °C. After separation and drying, grind them to obtain modified montmorillonite; in step S1, it is ensured that the montmorillonite and the second ionic liquid are in full contact and reaction, enabling the modified montmorillonite to form a nano-scale layered structure and be evenly dispersed in the nylon matrix, enhancing the "labyrinth effect", effectively hindering the penetration of water molecules, reducing the hygroscopicity of the nylon wheel, and reducing the risk of dimensional expansion.

[0045] S2: Put the caprolactam monomer and the modified montmorillonite in S1 into a reaction kettle at a temperature of 70 - 85°C, and stir for 0.5 - 2 h. After vacuum dehydration and adding the first ionic liquid, control the temperature at 135 - 150°C and react for 0.5 - 2 hours. This is beneficial for the ionic liquid to promote the formation of chemical bonds between nylon molecular chains, construct a three-dimensional network structure, enhance the barrier to water molecules, and further reduce the hygroscopicity.

[0046] Put the caprolactam monomer and the modified montmorillonite in S1 into a reaction kettle and stir at 70 - 85°C for 0.5 - 2 hours to fully mix the caprolactam monomer and the modified montmorillonite and carry out a preliminary reaction, which helps to enhance the interfacial bonding between the montmorillonite and the nylon matrix, lay a good foundation for the subsequent polymerization reaction, improve the load transfer efficiency, and delay the creep deformation.

[0047] S3: Add the catalyst and co-catalyst into the reaction kettle, control the pressure in the reaction kettle to be 0.05 - 0.1 MPa, carry out vacuum dehydration for 15 - 30 min, add the first ionic liquid, control the temperature to be 135 - 150°C, and continue to react for 0.5 - 2 h. Carry out vacuum dehydration operation to remove the moisture in the mixture to avoid affecting the polymerization reaction and the properties of nylon. At the same time, ensure that the first ionic liquid fully participates in the reaction, promote the formation of chemical bonds between molecular chains, and construct a stable three-dimensional network structure, thereby improving the anti-creep performance of the nylon wheel, making it not easy to deform under long-term load and solving the problem of dimensional expansion.

[0048] S4: Put the substances in the reaction kettle into a nylon wheel mold and carry out centrifugation. After taking out and cooling and curing, a modified cast nylon wheel is obtained. Putting the substances in the reaction kettle into the mold and carrying out centrifugation helps to eliminate bubbles, make the material evenly distributed and closely adhere to the mold wall, ensure that the internal structure of the nylon wheel is uniform and dense, without defects or loose areas. After cooling and curing, the overall performance of the nylon wheel is uniform, and the anti-creep performance is stable, further reducing the deformation and dimensional expansion caused by local stress concentration.

[0049] During the in-situ polymerization of nylon, one end of the functionalized ionic liquid binds to the hydroxyl groups on the surface of montmorillonite, and the other end reacts with the nylon amide bond to form a chemical bond, enhancing the interfacial bonding. This strong interfacial interaction restricts the movement of nylon molecular chains. Even after absorbing water, the swelling space of the molecular chains is restricted by the montmorillonite nanosheets, thereby reducing the volume change. In addition, the uniformly dispersed montmorillonite promoted by the ionic liquid can also delay the diffusion rate of water in nylon through the "nano-barrier effect", further reducing the volume fluctuation caused by moisture absorption.

[0050] The intercalation polymerization occurs between montmorillonite and the nylon matrix. The intercalation polymerization enables the nylon polymer chains to enter the interlayer space of the montmorillonite layers, enhancing the interfacial interaction between the two, effectively preventing the chain segment slippage of the matrix under stress, and improving the tensile strength and flexural modulus of the material. After intercalation polymerization, the montmorillonite nanosheets can play the role of stress concentration and dispersion in the matrix. When the material is subjected to external impact, the matrix around the nanosheets can absorb and dissipate more energy, thereby improving the impact toughness and elongation at break of the material.

[0051] During the intercalation polymerization process, chemical or physical interactions occur between the nylon polymer chains and the montmorillonite interlayers, forming a tight interfacial bond. This interaction can enhance the stability of the montmorillonite interlayer structure, make the layered structure more uniformly dispersed in the nylon matrix, construct a denser physical barrier, effectively hinder the water penetration, and provide a good foundation for the formation of a hydrophobic microenvironment.

[0052] After intercalation polymerization, the montmorillonite nanosheets form complex tortuous paths in the nylon matrix, making it difficult for water molecules to rapidly diffuse and penetrate inside the material, thereby reducing the hygroscopicity of the material and minimizing the dimensional expansion and property changes caused by moisture absorption. The presence of the montmorillonite nanosheets in the matrix exerts a physical restriction on the movement of the nylon polymer chains, making it more difficult for the chain segments to slide and displace under long-term load, thus improving the creep resistance of the material and reducing the deformation degree of the nylon wheel during use. Good intercalation polymerization makes the interfacial bond between the montmorillonite and the matrix closer, enabling the load to be more effectively transferred between the two, avoiding premature deformation and failure caused by local stress concentration, and further improving the dimensional stability and creep resistance of the nylon wheel.

[0053] The mass ratio of the total mass of the montmorillonite body and the second ionic liquid to water is 1:5 - 10. Within this mass ratio range, it can ensure that the second ionic liquid spreads and coats fully on the surface of the montmorillonite. Sufficient water volume can form a stable suspension dispersion system after mixing the montmorillonite and the second ionic liquid, enabling the second ionic liquid to be evenly distributed on the surface of the montmorillonite. After subsequent drying and grinding, the modified montmorillonite can form a nanoscale layered structure with good hydrophobicity, effectively delaying the water penetration path in the nylon wheel, reducing the hygroscopicity, and minimizing the risk of dimensional expansion.

[0054] This mass ratio is conducive to the full dispersion of the montmorillonite body in the water medium and avoids agglomeration. The uniformly dispersed montmorillonite can fully contact and react with the second ionic liquid, enabling the modified montmorillonite to be more uniformly dispersed in the nylon matrix during subsequent compounding with the nylon matrix, constructing a dense "labyrinth effect", further reducing the hygroscopicity, and also laying a foundation for improving the creep resistance.

[0055] It not only ensures sufficient reaction sites and media for montmorillonite and the second ionic liquid, but also does not cause difficulties in subsequent separation and drying due to excessive water or introduce too many impurities to affect the subsequent polymerization reaction. At the same time, an appropriate amount of water facilitates controlling the viscosity and fluidity of the reaction system, ensuring uniform stirring and mixing, enabling montmorillonite and the second ionic liquid to react fully and exert their modification effects, thereby better solving the problems of hygroscopicity and anti-creep performance.

[0056] The grinding process parameters in S1 are: the grinding speed is 300 - 500 r / min, and the grinding time is 20 - 40 min. Grinding within this speed range can effectively break up the aggregates after mixing montmorillonite bulk and the second ionic liquid, gradually refining the particles. At the same time, this speed not only ensures the grinding efficiency but also avoids generating too much heat due to too high a speed, preventing the heat from having an adverse impact on the structure and properties of montmorillonite and ionic liquid, such as causing the volatilization of ionic liquid or the destruction of the layered structure of montmorillonite.

[0057] Appropriate grinding parameters make the modified montmorillonite particles small and uniform. After being compounded with the nylon matrix, they can be filled in the matrix more densely, forming a more uniform nano-scale layered structure, enhancing the "labyrinth effect", further extending the water molecule penetration path, reducing the hygroscopicity of the nylon wheel, and reducing the size expansion caused by moisture absorption. The small and uniform modified montmorillonite particles have a closer interface bonding with the nylon matrix, improving the interface bonding strength and load transfer efficiency, making the stress evenly distributed between the matrix and montmorillonite, and reducing the deformation caused by local stress concentration. In addition, good dispersibility is conducive to constructing a stable three-dimensional network structure, improving the anti-creep performance of the nylon wheel, and reducing the risk of size expansion.

[0058] The centrifugal speed in S4 is 200 - 400 rpm. Under the condition of a centrifugal speed of 200 - 400 rpm, the bubbles existing after pouring the substances in the reaction kettle into the mold can be effectively removed, making the inside of the nylon wheel more dense, reducing pores and defects. This can reduce the water molecule penetration channels inside the nylon wheel, reduce hygroscopicity, and reduce the risk of size expansion.

[0059] It can make the reactants evenly distributed in the mold, especially components such as modified montmorillonite and ionic liquid can be more evenly dispersed in the nylon matrix. The evenly dispersed modified montmorillonite can construct a stable three-dimensional network structure, improving the overall stability and anti-creep performance of the nylon wheel, making it not easy to deform under long-term load, and reducing size expansion. Appropriate centrifugal speed helps to make the internal structure of the nylon wheel more uniform and dense, optimizing the internal stress distribution. During use, the performance of each part of the nylon wheel is consistent, and it can evenly bear the load and stress, avoiding the problems of deformation and size expansion caused by local stress concentration, thereby extending the service life.

[0060] The centrifugation time in S4 is 2 - 4 min. This can ensure that the substances in the reaction kettle are evenly distributed in the mold, and at the same time make the substances closely adhere to the mold wall, reducing internal pores and defects. The dense structure can effectively reduce the permeability of water molecules inside the nylon wheel, thereby reducing moisture absorption and the risk of dimensional expansion caused by moisture absorption.

[0061] Components such as modified montmorillonite and ionic liquids can be evenly dispersed in the nylon matrix to form a stable three-dimensional network structure. The uniform distribution of components helps to improve the overall stability and rigidity of the nylon wheel. When it is subjected to long-term loads, it can transfer stress more evenly, reduce local stress concentration, enhance creep resistance, and reduce the property of dimensional expansion.

[0062] An appropriate centrifugation time can avoid problems such as uneven distribution caused by too short time or material stratification caused by too long time, ensuring that the internal structure of the nylon wheel is uniform and dense. This helps to optimize the comprehensive performance of the nylon wheel, enabling it to better resist the effects of moisture absorption and creep deformation under the complex working conditions of port cranes, reducing dimensional expansion, and extending service life.

[0063] The specific models and sources of the materials in the following examples are shown in Table 1.

[0064] Table 1 Specific models and sources of materials in examples and comparative examples

[0065] Example 1: This example provides a modified cast nylon wheel. The raw materials of the modified cast nylon wheel include, by mass: 120 parts of caprolactam monomer, 6 parts of the first ionic liquid, 2 parts of modified montmorillonite, 0.5 part of catalyst, and 0.5 part of cocatalyst; The first ionic liquid is a pyridine-based ionic liquid. The modified montmorillonite includes a montmorillonite body and a second ionic liquid. The montmorillonite body is sodium-based montmorillonite, and the second ionic liquid is an imidazole-based ionic liquid. The mass ratio of the montmorillonite body to the second ionic liquid in the modified montmorillonite is 4:1.

[0066] A preparation process for a modified cast nylon wheel includes the following steps: S1: Place the montmorillonite body and the second ionic liquid in water and mix them. Stir at 70 °C for 4 h, separate and dry, and then grind to obtain modified montmorillonite. The mass ratio of the total mass of the montmorillonite body and the second ionic liquid to water is 1:10. The grinding process parameters are: grinding speed is 400 r / min, and grinding time is 30 min.

[0067] S2: Put the caprolactam monomer and the modified montmorillonite in S1 into the reaction kettle at a temperature of 85 °C and stir for 1 h; S3: Add the catalyst and cocatalyst into the reaction kettle, control the pressure in the reaction kettle to be 0.05 MPa, dehydrate under vacuum for 30 min, add the first ionic liquid, control the temperature to be 140 °C, and continue the reaction for 1 h; the catalyst is sodium hydroxide and the cocatalyst is isocyanate.

[0068] S4: Put the substances in the reaction kettle into a nylon wheel mold and conduct centrifugation. The centrifugation speed is 300 rpm and the centrifugation time is 3 min. After taking out and cooling and solidifying, a modified cast nylon wheel is obtained.

[0069] The structural formula of the first ionic liquid is:

[0070] wherein R1 and R2 are methyl and acetyl groups respectively, and X - is tetrafluoroborate.

[0071] The structural formula of the second ionic liquid is:

[0072] wherein R is C2H4SO3H and Y - is iodide ion.

[0073] Example 2: The difference between this example and Example 1 is that the mass fraction of the first ionic liquid is 8 parts, and the rest are the same.

[0074] Example 3: The difference between this example and Example 1 is that the mass fraction of the first ionic liquid is 10 parts, and the rest are the same.

[0075] Example 4: The difference between this example and Example 1 is that the mass fraction of the first ionic liquid is 12 parts, and the rest are the same.

[0076] Example 5: The difference between this example and Example 1 is that the mass fraction of the first ionic liquid is 14 parts, and the rest are the same.

[0077] Example 6: The difference between this example and Example 3 is that the mass fraction of the modified montmorillonite is 1 part, and the rest are the same.

[0078] Example 7: The difference between this example and Example 3 is that the mass fraction of the modified montmorillonite is 3 parts, and the rest are the same.

[0079] Example 8: The difference between this example and Example 3 is that the mass fraction of the modified montmorillonite is 4 parts, and the rest are the same.

[0080] Example 9: The difference between this example and Example 3 is that the mass fraction of the modified montmorillonite is 5 parts, and the rest are the same.

[0081] Comparative Example 1: This comparative example provides a preparation process for a nylon wheel, and the preparation process is as follows: Place 120 parts by mass of caprolactam monomer and 0.5 parts by mass of sodium hydroxide in a reaction kettle, control the pressure in the reaction kettle to be 0.05 MPa, perform vacuum dehydration for 30 min, control the temperature to be 140 °C, react for 1 h, put the substances in the reaction kettle into a nylon wheel mold and perform centrifugation, the centrifugation speed is 300 rpm, and the centrifugation time is 3 min. After taking out and cooling and curing, a modified cast nylon wheel is obtained.

[0082] Take samples of the same volume from Examples 1 to 9 and Comparative Example 1, and perform creep resistance performance testing and water absorption testing respectively. The creep resistance performance testing is carried out according to the standard ISO 899 at 60 °C for 1000 h, and the water absorption testing is carried out according to the standard GB / T 1034-2008. The test data are shown in Table 2.

[0083] Table 2 Creep resistance performance testing and water absorption testing of Examples 1 to 9 and Comparative Example 1

[0084] As can be seen from Table 1, the tensile creep moduli of Examples 1 to 9 are all greater than that of Comparative Example 1, and the water absorption rates are all less than that of Comparative Example 1. The present application has superiority.

[0085] In Examples 1 to 5, as the mass fraction of the first ionic liquid gradually increases, both the creep resistance performance and the moisture absorption resistance first increase and then decrease. This is because as the mass fraction of the first ionic liquid increases, its ability to promote the formation of chemical bonds between nylon molecular chains is enhanced, and the constructed three-dimensional network structure is more dense, restricting the movement of nylon molecular chains, making the nylon wheel less likely to undergo creep deformation under long-term load. The appropriate amount of the first ionic liquid, the second ionic liquid and montmorillonite act synergistically to form a denser and more uniform hydrophobic layer on the surface of montmorillonite, effectively preventing water molecules from contacting montmorillonite and the nylon matrix, and at the same time enhancing the hydrophobicity between and on the surface of montmorillonite layers, making it more difficult for water molecules to approach and penetrate the montmorillonite layers; but when the amount increases too much, it causes the flexibility of the nylon matrix to decrease, the material becomes brittle, and local stress concentration is more likely to occur when subjected to load, resulting in defects such as microcracks inside the material, which instead reduces the creep resistance performance. And excessive first ionic liquid will damage the interfacial bonding between montmorillonite and the nylon matrix, resulting in defects or pores at the interface, making it easier for water molecules to penetrate into the nylon matrix, thereby reducing the moisture absorption resistance. The preferred example is Example 3.

[0086] In Example 3 and Examples 6 to 9, as the mass fraction of modified montmorillonite gradually increases, the creep resistance and hygroscopic resistance both increase first and then decrease, because the appropriate increase in the mass fraction of modified montmorillonite can further enhance the interfacial bonding strength between montmorillonite and nylon matrix, make the load transfer more uniform, reduce stress concentration, and thus slow down the creep deformation rate. The nano-scale layered structure formed by the modified montmorillonite is more evenly dispersed in the nylon matrix, constructs a denser three-dimensional network structure, restricts the movement of nylon molecular chains, improves the rigidity and stability of the material, and thus improves the creep resistance; the formed nano-scale layered structure is denser and more uniform in the nylon matrix, constructs a more complex "maze effect", makes the penetration path of water molecules inside the nylon wheel more tortuous and long, prolongs the time for water molecule penetration, reduces the adsorption capacity of the nylon wheel to water molecules, and thus improves the hygroscopic resistance.

[0087] The first ionic liquid and the second ion can work together between the montmorillonite and the nylon matrix to enhance the interface bonding strength. The first ionic liquid promotes the formation of chemical bonds between nylon molecular chains to build a three-dimensional network structure, while the montmorillonite modified by the second ionic liquid provides physical support and restraint. This synergistic effect makes the nylon wheel more stable under long-term load and improves its creep resistance.

[0088] When the mass fraction of modified montmorillonite is too high, its dispersibility in the nylon matrix will be deteriorated and agglomeration will occur. Agglomerated montmorillonite cannot effectively participate in the stress dispersion of the matrix, but becomes a stress concentration source, resulting in defects such as microcracks inside the material, thereby reducing creep resistance. Agglomeration causes pores and defects inside the material, which provide new channels for water molecules to penetrate, causing water molecules to enter the nylon matrix more easily, thereby reducing hygroscopicity. And too much montmorillonite indicates that the second ionic liquid is too much, which will destroy the interface bonding between montmorillonite and the nylon matrix, reduce the load transfer efficiency, reduce creep resistance and improve hygroscopicity. The preferred embodiment is embodiment seven.

[0089] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A modified cast nylon wheel, characterized in that, The modified cast nylon wheel raw material comprises, by weight: 80-120 parts of caprolactam monomer, 8-12 parts of a first ionic liquid, 2-4 parts of modified montmorillonite, 0.1-1 parts of a catalyst and 0.1-1 parts of a co-catalyst; The first ionic liquid is a pyridine ionic liquid, the modified montmorillonite comprises a montmorillonite body and a second ionic liquid, the montmorillonite body is one of sodium-based montmorillonite and calcium-based montmorillonite, and the second ionic liquid is an imidazole ionic liquid; The structural formula of the first ionic liquid is: ； wherein R1 and R2 are each independently one of methyl, ethyl, butyl and acetate group, and X - is one of chloride ion, bromide ion and tetrafluoroborate ion; The structural formula of the second ionic liquid is: ； wherein R is C n H 2n SO3H (n is an integer, 1 ≤ n ≤ 4), Y - is one of chloride ion, bromide ion, iodide ion and acetate ion.

2. The modified cast nylon wheel according to claim 1, characterized in that: The raw material mass ratio of the montmorillonite body and the second ionic liquid in the modified montmorillonite is 80-95:5-20.

3. A modified cast nylon wheel according to claim 1, characterized in that: The catalyst is one of sodium hydroxide, potassium hydroxide and sodium carbonate, and the co-catalyst is isocyanate.

4. A preparation process for a modified cast nylon wheel, based on the modified cast nylon wheel according to any one of claims 1-3, characterized in that, The following steps are involved: S1: mixing the montmorillonite body and the second ionic liquid in water, stirring for 3-4 hours at 60-70°C, separating, drying, and grinding to obtain modified montmorillonite; S2: Put the caprolactam monomer and the modified montmorillonite in S1 into a reactor at a temperature of 70-85° C. and stir for 0.5-2 h; S3: Add the catalyst and the co-catalyst into the reactor, control the pressure in the reactor to 0.05-0.1 MPa, vacuum dehydrate for 15-30 min, add the first ionic liquid, control the temperature to 135-150° C., and continue the reaction for 0.5-2 h; S4: placing the material in the reaction kettle into a nylon wheel mold and centrifuging it, taking it out, cooling it and solidifying it to obtain a modified cast nylon wheel.

5. The preparation process of a modified cast nylon wheel according to claim 4, characterized in that: The mass ratio between the total mass of the montmorillonite body and the second ionic liquid and water is 1:5-10.

6. The preparation process of a modified cast nylon wheel according to claim 4, characterized in that: The grinding process parameters in S1 are: grinding speed is 300-500r / min, and grinding time is 20-40min.

7. The preparation process of a modified cast nylon wheel according to claim 4, characterized in that: The centrifugal speed in S4 is 200-400 rpm.

8. The preparation process of a modified cast nylon wheel according to claim 4, characterized in that: The centrifugation time in S4 is 2-4 minutes.

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