Modified nylon 6 material as well as preparation method and application thereof

Abstract

The invention relates to a modified nylon 6 material as well as a preparation method and application thereof. The modified nylon 6 material is prepared from the following components in parts by weight: 80-95 parts of nylon 6 slices; 2 to 5 parts of nano titanium dioxide; 0.1 to 0.5 part of a silane coupling agent; 0.5 to 1 part of an antioxidant; 0.3 to 0.8 part of a lubricant; and 3-8 parts of a compatilizer. Wherein the mass ratio of the nano titanium dioxide to the silane coupling agent is 1: (0.05-0.1), the nano titanium dioxide reacts with the silane coupling agent to obtain modified nano titanium dioxide, and then the modified nano titanium dioxide is mixed with nylon 6 slices; the compatilizer is a maleic anhydride grafted ethylene-octylene copolymer. The modified nylon 6 material provided by the invention realizes synergistic improvement of water absorption, low-temperature impact resistance and weather resistance, has low water absorption, high impact strength, excellent weather resistance and good processability, and is suitable for the fields of automobile engine peripheral parts, outdoor equipment shells and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of nylon 6 polymer materials, and in particular to a modified nylon 6 material, a preparation method thereof, and an application thereof. Background Art

[0002] Since its invention in the 1930s, nylon 6, also known as polyamide 6 (PA6), has held a pivotal position in the industrial sector thanks to its unique molecular structure and performance characteristics. The amide groups in its molecular chain impart excellent mechanical properties to nylon 6, enabling it to excel in high-strength, high-wear-resistance applications such as automotive engine parts, mechanical gears, and outdoor equipment housings. Furthermore, nylon 6 exhibits excellent heat resistance and maintains stable performance over a wide temperature range, which has led to its widespread use in the electronics and electrical sector, such as in insulation materials for wire and cable and appliance housings.

[0003] However, with the continuous advancement of science and technology and the increasing complexity of industrial applications, the performance requirements for engineering plastics are also constantly increasing. The shortcomings of nylon 6 are gradually becoming apparent. First, because its molecular structure contains a large number of polar amide groups, which can form hydrogen bonds with water molecules, it has a high water absorption, resulting in a decrease in its dimensional stability, which in turn affects the precision and performance of the product. Secondly, nylon 6 has poor low-temperature impact resistance. In low-temperature environments, the mobility of its molecular chain segments is reduced, the material becomes brittle and hard, and is prone to brittle fracture. In addition, the insufficient weather resistance of nylon 6 is also a problem that needs to be solved urgently. Long-term exposure to outdoor environments, factors such as ultraviolet rays, oxygen, and temperature changes will accelerate the aging process of nylon 6, causing its mechanical properties to decline significantly, and cracks and discoloration to appear on the surface.

[0004] To overcome these shortcomings, researchers have been exploring various modification methods. Common approaches include filler addition, blending, and chemical modification. For example, adding glass fiber can improve the rigidity and dimensional stability of nylon 6, but this may result in a decrease in the material's toughness. Adding UV inhibitors can enhance its weather resistance, but this may affect other properties or increase the material's cost. Therefore, finding a cost-effective modification method that can comprehensively enhance the performance of nylon 6 has become a hot topic and a challenge in current research. Summary of the Invention

[0005] The present invention aims to overcome the deficiencies in the prior art and to provide a modified nylon 6 material and its preparation method and application. The modified nylon 6 material is made of nylon 6 slices, nano-titanium dioxide, a silane coupling agent, an antioxidant, a lubricant and a compatibilizer, by pre-treating the nano-titanium dioxide with a silane coupling agent, and melt-blending with components such as nylon 6 slices and a compatibilizer POE-g-MAH, thereby achieving a synergistic improvement in water absorption, low-temperature impact resistance and weather resistance. The modified nylon 6 material has low water absorption, high low-temperature impact resistance, excellent weather resistance and good processing properties, and can be widely used in automobiles (such as engine parts, peripheral components), electronic appliances (such as insulating materials of wires and cables, home appliance housings), machinery manufacturing (such as mechanical gears), outdoor equipment housings and other fields.

[0006] In one aspect, the present invention provides a modified nylon 6 material, which is made from the following raw materials in parts by weight:

[0007] Nylon 6 chips: 80-95 parts

[0008] Nano titanium dioxide: 2-5 parts

[0009] Silane coupling agent: 0.1-0.5 parts

[0010] Antioxidant: 0.5-1 part

[0011] Lubricant: 0.3-0.8 parts

[0012] Compatibilizer: 3-8 parts

[0013] The mass ratio of nano-titanium dioxide to silane coupling agent is 1:0.05-0.1, and the nano-titanium dioxide and silane coupling agent are reacted to obtain silane coupling agent-modified nano-titanium dioxide, which is then mixed with nylon 6 chips;

[0014] The compatibilizer is maleic anhydride grafted ethylene-octene copolymer (POE-g-MAH).

[0015] In an embodiment, the total weight of nylon 6 chips, nano titanium dioxide, silane coupling agent, antioxidant, lubricant, and compatibilizer is 100 parts.

[0016] Each of the above components is described in detail below.

[0017] Nylon 6 chips

[0018] Nylon 6 chips, also known as polyamide 6 chips or nylon 6 chips, are polymer compounds made from caprolactam as raw material, adding a certain amount of additives, polymerizing under certain process conditions, and then undergoing processes such as injection molding, pelletizing, extraction, and vacuum drying. Its structure can be expressed as -[NH(CH2)5CO] nFor example, in the embodiments of the present invention, nylon 6 chips are produced by Dongming Xuyang Chemical Co., Ltd. through ring-opening polymerization of caprolactam. According to the industry standard FZ / T 51004-2011 "Fiber-grade polycaprolactam chips," the product has a relative viscosity of 2.80±0.05, a hot water extractable content of ≤0.05%, and a water content of ≤600 ppm.

[0019] In the present invention, nylon 6 chips are used as the matrix resin. Based on a total of 100 parts by weight of the modified nylon 6 material, the amount used can be 80-95 parts by weight, for example 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, and 95 parts by weight. Within the above-mentioned amount range, the inherent properties of nylon 6 (such as high crystallinity and good mechanical strength) can be retained while meeting the modification requirements. If the amount is too low, it is impossible to ensure that the material maintains the skeleton support function of nylon 6, while if the amount is too high, the necessary space for functional additives cannot be reserved.

[0020] Nano-titanium dioxide

[0021] In the present invention, the nano-titanium dioxide is nano-titanium dioxide particles with a particle size of 20-50 nm. The particle size here refers to the equivalent spherical diameter: the diameter of the particle assuming it is spherical, which can be measured by dynamic light scattering.

[0022] Within the above particle size range, nano-titanium dioxide has a large specific surface area that can effectively absorb ultraviolet rays while avoiding the agglomeration problem of too small particles. If the particle size is too small, it is easy to agglomerate, while if the particle size is too large, the specific surface area and activity may be reduced.

[0023] In the present invention, based on a total of 100 parts by weight of modified nylon 6 material, the amount of nano titanium dioxide can be 2-5 parts by weight, for example, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 parts by weight. The above dosage range is based on the comprehensive optimization of its functionality, processing performance, and cost-effectiveness. If the dosage is too low, it may lead to insufficient functionality: the concentration of nanoparticles is not enough to form a continuous reinforcement network, and the anti-ultraviolet performance is less than 50%; while if the dosage is too high, it may lead to deterioration of mechanical properties: excessive particles induce stress concentration, resulting in a decrease in impact strength and increased brittleness of the material; or it may cause processing difficulties: the melt viscosity increases significantly, resulting in incomplete injection molding or an increase in spinning breakage rate; or it may affect optical properties: a high addition amount causes the material transmittance to drop by more than 40%, limiting its application in transparent or light-colored products.

[0024] Silane coupling agent

[0025] In the present invention, the silane coupling agent is a compound having various organic functional groups, which is used to react with nano-titanium dioxide to prepare modified nano-titanium dioxide, thereby improving the dispersibility and compatibility of nano-titanium dioxide in nylon 6 and reducing agglomeration.

[0026] The silane coupling agent may have a structure as shown below:

[0027] (Y) m -R-Si-(X)3,

[0028] in,

[0029] m is 1 or 2;

[0030] Y is selected from amino (-NH2), epoxy, hydroxyl, and thiol;

[0031] R is selected from a divalent or trivalent C2 to C10 alkyl group or a group in which one or more (e.g., 1, 2, 3, 4, 5) carbon atoms in the alkyl group are replaced by O or N; preferably, R is selected from a C3 to C6 alkylene group (e.g., propylene (-CH2CH2CH2-)), -(CH2)2NH(CH2)3-,

[0032] (CH2)3NH(CH2)2NH(CH2)2, (CH2)3N(CH2CH2-)2, CH2O(CH2)3;

[0033] At least one X is a C1 to C4 alkoxy group, and the remaining X groups are independently selected from C1 to C4 alkoxy groups and C1 to C4 alkoxy groups. Preferably, at least one X group is selected from methoxy or ethoxy groups, and the remaining X groups are independently selected from methyl, ethyl, methoxy, and ethoxy groups.

[0034] In the silane coupling agent, Y is an organic functional group responsible for reacting with organic materials (such as polymers and resins); R is the group connecting the silicon atom and the Y group; the alkoxy group in X can be hydrolyzed, thereby allowing Si to combine with the surface of inorganic materials (such as glass, metal, and filler).

[0035] In an embodiment, the silane coupling agent may be, for example, selected from aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, and the like.

[0036] Aminosilane coupling agents may be, for example, KH-540 (γ-aminopropyltrimethoxysilane, structural formula: H2N(CH2)3Si(OCH3)3), KH-550 (3-aminopropyltriethoxysilane, structural formula: NH2(CH2)3Si(OC2H5)3), KH-792 (N-2-aminoethyl-3-aminopropyltrimethoxysilane, structural formula: NH2(CH2)2NH(CH2)3Si(OCH3)3), Si-550 (Si-602 modified product, N-2-aminoethyl-3-aminopropylmethyldimethoxysilane, structural formula: NH2(CH2)2NH(CH2)3SiCH3(OCH3)2), Si-602 (N-2-aminoethyl-3-aminopropylmethyldimethoxysilane, structural formula:

[0037] NH2(CH2)2NH(CH2)3SiCH3(OCH3)2), Si-603 (γ-diethylenetriaminepropylmethyldimethoxysilane, structural formula: CH3(CH3O)2Si(CH2)3NH(CH2)2NH(CH2)2NH2 or CH3(CH3O)2Si(CH2)3N(CH2CH2NH2)2), Si-902 (γ-aminopropylmethyldiethoxysilane, structural formula: NH2(CH2)3SiCH3(OC2H5)2), but not limited thereto.

[0038] Epoxysilane coupling agents may be, for example, KH-560 (3-glycidoxypropyltrimethoxysilane, structural formula: CH2OCHCH2O(CH2)3Si(OCH3)3), KH-561 (3-(2,3-epoxypropyloxy)propyltriethoxysilane, structural formula: CH2OCHCH2O(CH2)3Si(OC2H5)3), KH-562 (3-(2,3-epoxypropyloxy)propylmethyldimethoxysilane, structural formula:

[0039] CH2OCHCH2O(CH2)3SiCH3(OC2H5)2), but not limited thereto.

[0040] Mercaptosilane coupling agents may be, for example, KH-580 (3-mercaptopropyltriethoxysilane, structural formula: HS(CH2)3Si(OC2H5)3) or KH-590 (3-mercaptopropyltrimethoxysilane, structural formula: HS(CH2)3Si(OCH3)3), but are not limited thereto.

[0041] In particular, γ-aminopropyltriethoxysilane (KH-550): with a structural formula of NH2-(CH2)3-Si(OC2H5)3, its Y group is an amino group (-NH2), which can form hydrogen bonds with the amide groups in nylon 6, enhancing affinity with the organic phase. γ-glycidoxypropyltrimethoxysilane (KH-560): with a structural formula of CHOCHCH2O(CH2)3Si(OCH3)3, its Y group is an epoxy group (CH2OCH-), which can chemically react with nylon 6 and improve interfacial bonding. γ-mercaptopropyltrimethoxysilane (KH-590): with a structural formula of HSCH2CH2CH2Si(OCH3)3, its Y group is a mercapto group (-SH), which can react with the polar groups in nylon 6, improving compatibility.

[0042] These silane coupling agents interact with nylon 6 through their respective Y groups, while the X groups hydrolyze to allow Si to react with the hydroxyl groups on the surface of nano-titanium dioxide to form a chemical bond, thereby combining the inorganic properties of nano-titanium dioxide with the organic properties of nylon 6, and improving the dispersibility and compatibility of nano-titanium dioxide in nylon 6.

[0043] In the present invention, the mass ratio of nano-titanium dioxide to silane coupling agent is 1:0.05-0.1, for example, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, etc., but not limited thereto. Within the above ratio range, the surface of the nano-titanium dioxide can be fully chemically modified, achieving optimal dispersibility and compatibility of the nano-titanium dioxide in the nylon 6 matrix. If the amount of silane coupling agent is too low, the modification effect on the surface of nano-titanium dioxide will be insufficient, and a large number of nano-titanium dioxide particles cannot be effectively coated by the silane coupling agent, resulting in poor dispersion in the nylon 6 matrix. If the amount of silane coupling agent is too high, it may form an independent phase in the nylon 6 matrix or deteriorate the compatibility with the matrix, which will cause microphase separation inside the material, destroy the uniformity of the matrix, and thus reduce the overall performance of the material. At the same time, excessive silane coupling agent may migrate to the surface of the material, affecting the surface properties of the material, such as increasing the unevenness of the surface hydrophobicity, and may even precipitate during subsequent processing, affecting the processing performance of the material and the appearance quality of the product.

[0044] In an embodiment, the reaction of the silane coupling agent and the nano-titanium dioxide is carried out as follows: the nano-titanium dioxide and the silane coupling agent are mixed in a mass ratio of 1:0.05-0.1, and stirred at 60-80° C. for 2-4 hours.

[0045] antioxidants

[0046] In the present invention, the antioxidant is used to prevent the modified nylon 6 material from being degraded due to oxidation during processing and use, thereby extending the service life of the material and maintaining its excellent performance.

[0047] In an embodiment, the antioxidant can be one or more combinations of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants. Common hindered phenol antioxidants are such as tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester (Antioxidant 1010), di-tert-butyl-p-cresol (BHT), etc., and this type of antioxidant has good thermal stability and long-term antioxidant performance, is mainly used for capturing free radicals, terminates free radical chain reactions, thereby suppresses the thermal oxidation degradation process of materials. Phosphite antioxidants are such as triisododecyl phosphite (Antioxidant 168), etc., and their main function is to decompose peroxides, prevent peroxide accumulation from causing material degradation, and also can synergize with hindered phenol antioxidants to improve overall antioxidant effect. Thioester antioxidants then generate stable products by reacting with free radicals, thereby suppressing the carrying out of oxidation reaction.

[0048] In the present invention, based on a total of 100 parts by weight of modified nylon 6 material, the amount of antioxidant can be 0.5-1 parts by weight, for example 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 parts by weight. Within the above-mentioned dosage range, the antioxidant's antioxidant effect can be fully exerted, effectively suppressing the oxidative degradation of the material during processing and use, ensuring that the material can still maintain good mechanical properties, dimensional stability and appearance quality after long-term use. At the same time, an appropriate amount of antioxidant can synergize with other additives (such as compatibilizers, lubricants, etc.) to jointly improve the comprehensive performance of the material. If the dosage is too low, the antioxidant's protective effect on the material is insufficient, and it is impossible to effectively capture free radicals and decompose peroxides. During high-temperature processing, the nylon 6 matrix is ​​prone to thermal oxidative degradation, resulting in problems such as a decrease in the mechanical properties of the material and yellowing of the color. In addition, the weather resistance and dimensional stability of the material during long-term use will also be affected, shortening the service life of the material. While too high an amount can further enhance the material's antioxidant properties, it will increase the production cost of the material. At the same time, excessive antioxidants may migrate within the material, affecting its surface properties. For example, they may cause precipitates to form on the surface of the finished product, affecting its appearance and adhesion to other materials or coatings. Furthermore, excessive antioxidants may interact with other additives, affecting the overall performance balance of the material. For example, this may adversely affect its processing properties and reduce its melt flowability and processing stability.

[0049] lubricant

[0050] In the present invention, the lubricant is used to reduce the melt viscosity of the nylon 6 material during processing, improve its fluidity and demoulding performance, thereby improving the processing performance of the material, reducing the wear of processing equipment, and helping to improve the surface quality of the product.

[0051] In an embodiment, the lubricant can be one or more combinations of fatty acids and their salts (e.g., stearic acid, zinc stearate), fatty acid esters (e.g., glycerol monostearate), silicone oils (e.g., polydimethylsiloxane (PDMS)), polyethylene glycol (PEG) lubricants (e.g., PEG 400, PEG 6000), etc. These lubricants can form a lubricating film in the nylon 6 matrix, reducing friction between molecular chains, thereby lowering melt viscosity.

[0052] Among the present invention, based on the modified nylon 6 material of 100 weight parts in total, the consumption of lubricant can be 0.3-0.8 weight part, for example 0.3,0.4,0.5,0.6,0.7,0.8 weight part.Within the above-mentioned amount range, the melt viscosity of nylon 6 can be effectively reduced, its processing fluidity can be improved, material is made to be easier to shape in the processes such as injection molding, extrusion, and the surface finish of goods can also be improved simultaneously, and surface defect is reduced. If consumption is too low, then lubricating effect is not obvious, and the melt viscosity of nylon 6 is still higher, needs bigger shearing force in the process of processing, may cause the abrasion aggravation of processing equipment, also can increase the degradation risk of material in the process of processing, affect the quality and performance of goods, and consumption is too high, then excessive lubricant may form independently phase in material internal, affect the interaction between nylon 6 matrix and other additives (such as nano titanium dioxide, compatibilizer etc.), thereby reduce the mechanical property of material, such as tensile strength and flexural modulus. In addition, excessive lubricant may migrate to the surface of the material, resulting in oil stains or precipitates on the surface of the product, affecting the appearance quality and adhesion with other materials or coatings.

[0053] Compatibilizer

[0054] In the present invention, the compatibilizer is used to improve the compatibility between nylon 6 and nano-titanium dioxide, increase the bonding force between the two, and thus enhance the comprehensive performance of the material.

[0055] In the present invention, the compatibilizer is maleic anhydride-grafted ethylene-octene copolymer (POE-g-MAH). The structure of POE-g-MAH is: maleic anhydride groups are chemically grafted onto the backbone of ethylene-octene copolymer (POE). This grafted structure gives POE-g-MAH excellent compatibility with the nylon 6 matrix and enables it to interact with the silane coupling agent on the surface of the nano-titanium dioxide, forming a stable network structure.

[0056] In an embodiment, POE-g-MAH can be a commercially available product, such as a product purchased from The Dow Chemical Company (trade name such as GA 1901). Alternatively, it can be prepared according to existing graft polymerization methods, such as by melt grafting or solution grafting, to graft maleic anhydride onto the ethylene-octene copolymer.

[0057] In the present invention, based on the modified nylon 6 material of 100 weight parts in total, the consumption of compatibilizer can be 3-8 weight part, for example 3,4,5,6,7,8 weight parts.Within the above-mentioned amount range, the compatibilization of POE-g-MAH can be fully given play, nano titanium dioxide is evenly dispersed in the nylon 6 matrix, forms an effective toughening phase, thereby significantly improves the impact strength and the low temperature resistance of material. If consumption is too low, then can't fully improve the compatibility between nylon 6 and the nano titanium dioxide, the dispersibility of nano titanium dioxide in matrix is ​​still poor, causes the impact strength and the overall performance of material to improve limited, and consumption is too high, then excessive compatibilizer can increase material cost, and may cause the rigidity of material to decline, affects its dimensional stability and high temperature performance.

[0058] Figure 1 A schematic diagram of the microstructure of the modified nylon 6 material according to the present invention is shown, wherein the nylon 6 matrix (PA6Matrix): serves as a continuous phase and constitutes the basic framework of the material. Nano-titanium dioxide (Nano-TiO2): is evenly dispersed in the nylon 6 matrix to form a dense network structure. Compatibilizer (POE-g-MAH): is wrapped on the surface of the nano-titanium dioxide particles and connected to the nylon 6 matrix, thereby improving compatibility. Antioxidant (Antioxidant): is distributed in the nylon 6 matrix to prevent oxidative degradation. Lubricant (Lubricant): is distributed in the nylon 6 matrix to reduce the friction between molecular chains and improve processing performance. This microstructure enables the modified nylon 6 material to have low water absorption, high low-temperature impact resistance and excellent weather resistance.

[0059] Another aspect of the present invention provides a method for preparing a modified nylon 6 material, comprising the following steps:

[0060] 1. Dry the nylon 6 slices at 80-100℃ for 4-6 hours;

[0061] 2. Mix nano-titanium dioxide and silane coupling agent in a mass ratio of 1:0.05-0.1, and stir and react at 60-80°C for 2-4 hours to obtain modified nano-titanium dioxide;

[0062] 3. Add the dried nylon 6 chips, modified nano titanium dioxide, antioxidant, lubricant and compatibilizer into a high-speed mixer and mix at 110-130°C for 5-10 minutes;

[0063] 4. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 220-260°C and a screw speed of 300-500 r / min. After extrusion, the material is cooled and pelletized to obtain modified nylon 6 particles.

[0064] In step 1, the drying temperature can be 80, 85, 90, 95 or 100° C., but not limited thereto, and the drying time can be 4, 4.5, 5, 5.5 or 6 hours, but not limited thereto. By drying the nylon 6 chips, their moisture content can be reduced, ensuring the smooth progress of subsequent reactions.

[0065] In step 2, the mass ratio of nano-titanium dioxide to silane coupling agent is the same as described above. The reaction temperature can be, but is not limited to, 60, 65, 70, 75, or 80°C, and the reaction time can be, but is not limited to, 2, 2.5, 3, 3.5, or 4 hours. Surface modification of nano-titanium dioxide using a silane coupling agent can improve its dispersibility and compatibility in nylon 6 and reduce agglomeration.

[0066] In step 3, the high-speed mixer can be a vertical or horizontal mixer. Common brands include the ZH series mixers from Werner & Pfleiderer in Germany and the high-speed mixers from Yongchuang Machinery in Zhangjiagang, Jiangsu. This mixing ensures that all components are thoroughly mixed, ensuring that the additives are evenly dispersed in the nylon 6 matrix during the subsequent melt extrusion process.

[0067] In step 4, the twin-screw extruder can be a parallel twin-screw extruder or a conical twin-screw extruder, such as the ZSE series twin-screw extruder of Leistritz, Germany, or the KTP series twin-screw extruder of Nanjing Keya.

[0068] Another aspect of the present invention provides a product comprising the modified nylon 6 material according to the present invention. The product may be, for example, automotive engine parts and peripheral components, mechanical gears, insulation materials for wires and cables, housings for household appliances, housings for outdoor equipment, and the like.

[0069] Beneficial effects

[0070] The present invention modifies nylon 6 by adding nano-titanium dioxide and compatibilizer POE-g-MAH, thereby significantly improving the comprehensive properties of nylon 6:

[0071] Reduce water absorption: Nano-titanium dioxide is evenly dispersed in the nylon 6 matrix to form a dense network structure, which effectively hinders the penetration of water molecules and reduces the water absorption rate of the modified nylon 6 material by more than 50%.

[0072] Improve low-temperature impact resistance: The compatibilizer POE-g-MAH has good compatibility with nylon 6 and can form a toughening phase in the nylon 6 matrix to absorb impact energy, thereby increasing the impact strength of the material at low temperatures by more than 40%.

[0073] Enhanced weather resistance: Nano titanium dioxide has good UV shielding effect, can effectively absorb and scatter ultraviolet rays, reduce the degradation effect of ultraviolet rays on nylon 6, and significantly improve the weather resistance of the modified nylon 6 material when used outdoors, extending its service life.

[0074] Improve processing performance: The addition of compatibilizer POE-g-MAH reduces the melt viscosity of nylon 6, improves its fluidity, makes the material easier to shape during processing, and reduces processing difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 A schematic diagram showing the microstructure of the modified nylon 6 material according to the present invention.

[0076] Figure 2 A schematic diagram showing the preparation process of the modified nylon 6 according to the present invention used in the examples is shown. DETAILED DESCRIPTION

[0077] The present invention is further described below by way of specific examples, but the present invention is not limited to the following examples.

[0078] Figure 2 A schematic diagram showing the preparation process of the modified nylon 6 according to the present invention used in the following examples is shown.

[0079] Reagents and materials

[0080] Nylon 6 chips are produced by Dongming Xuyang Chemical Co., Ltd. and are measured according to the industry standard FZ / T51004-2011 "Fiber-grade polycaprolactam chips". The product has a relative viscosity of 2.80±0.05, hot water extractable matter ≤0.05%, and a water content ≤600ppm.

[0081] The nano-titanium dioxide is Degussa P25, with an average particle size of 21 nm.

[0082] The silane coupling agent is KH-550, NH2-(CH2)3-Si(OC2H5)3.

[0083] The antioxidant was pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Antioxidant 1010).

[0084] The lubricant is zinc stearate.

[0085] POE-g-MAH was purchased from The Dow Chemical Company, USA GA 1901.

[0086] The high-speed mixer is a ZH10 mixer from Werner & Pfleiderer of Germany.

[0087] The twin-screw extruder is a ZSE18 twin-screw extruder from Leistritz, Germany.

[0088] Example 1

[0089] 1. Dry 90 parts of nylon 6 chips at 90°C for 5 hours.

[0090] 2. Mix 3 parts of nano-titanium dioxide and silane coupling agent in a mass ratio of 1:0.1, and stir and react at 70°C for 3 hours.

[0091] 3. Add the dried nylon 6 chips, surface-treated nano-titanium dioxide, 1 part of antioxidant, 0.7 parts of lubricant and 5 parts of POE-g-MAH into a high-speed mixer and mix at 120° C. for 8 minutes.

[0092] 4. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 240°C and a screw speed of 400 r / min. After extrusion, the material is cooled and pelletized to obtain modified nylon 6 particles.

[0093] Example 2

[0094] 1. Dry 85 parts of nylon 6 chips at 90°C for 5 hours.

[0095] 2. Mix 5 parts of nano-titanium dioxide and silane coupling agent in a mass ratio of 1:0.08, and stir at 70°C for 3 hours.

[0096] 3. Add the dried nylon 6 chips, surface-treated nano-titanium dioxide, 1 part of antioxidant, 0.6 parts of lubricant and 8 parts of POE-g-MAH into a high-speed mixer and mix at 120° C. for 8 minutes.

[0097] 4. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 240°C and a screw speed of 400 r / min. After extrusion, the material is cooled and pelletized to obtain modified nylon 6 particles.

[0098] Example 3

[0099] 1. Dry 95 parts of nylon 6 chips at 90°C for 5 hours.

[0100] 2. Mix 2 parts of nano-titanium dioxide and silane coupling agent in a mass ratio of 1:0.05, and stir and react at 70°C for 3 hours.

[0101] 3. Add the dried nylon 6 chips, surface-treated nano-titanium dioxide, 0.5 parts of antioxidant, 0.4 parts of lubricant and 2 parts of POE-g-MAH into a high-speed mixer and mix at 120° C. for 8 minutes.

[0102] 4. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 240°C and a screw speed of 400 r / min. After extrusion, the material is cooled and pelletized to obtain modified nylon 6 particles.

[0103] Comparative Example 1 (unmodified nylon 6)

[0104] 1. Dry 100 parts of nylon 6 chips at 90°C for 5 hours.

[0105] 2. The dried nylon 6 chips were directly melt-extruded through a twin-screw extruder at an extrusion temperature of 240°C and a screw speed of 400 r / min. After extrusion, they were cooled and pelletized to obtain unmodified nylon 6 particles.

[0106] Comparative Example 2 (adding only nano titanium dioxide)

[0107] 1. Dry 94.6 parts of nylon 6 chips at 90°C for 5 hours.

[0108] 2. Mix 5 parts of nano-titanium dioxide and silane coupling agent in a mass ratio of 1:0.08, and stir at 70°C for 3 hours.

[0109] 3. Add the dried nylon 6 chips and surface-treated nano-titanium dioxide into a high-speed mixer and mix at 120°C for 8 minutes.

[0110] 4. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 240° C. and a screw speed of 400 r / min. After extrusion, the material is cooled and pelletized to obtain nylon 6 particles with only nano-titanium dioxide added.

[0111] Comparative Example 3 (adding only the compatibilizer POE-g-MAH)

[0112] 1. Dry 95 parts of nylon 6 chips at 90°C for 5 hours.

[0113] 2. Add the dried nylon 6 chips and 5 parts of POE-g-MAH into a high-speed mixer and mix at 120°C for 8 minutes.

[0114] 3. The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 240°C and a screw speed of 400 r / min. After extrusion, the material is cooled and pelletized to obtain nylon 6 pellets with only the compatibilizer added.

[0115] Performance Testing

[0116] The nylon 6 pellets obtained in Examples 1-3 and Comparative Examples 1-3 were dried in an oven at 120°C for 5 hours. The dried pellets were then injection molded in a twin-screw injection molding machine at an injection temperature of 240°C and a mold temperature of 50°C to produce standard specimens for testing.

[0117] Water absorption is tested according to GB / T 38138-2019 standard.

[0118] Low temperature impact strength is tested according to GB / T 1043.1-2008 standard.

[0119] The tensile strength is tested according to GB / T 1040.1-2018 standard.

[0120] The flexural modulus is tested according to GB / T 9341-2008 standard.

[0121] The melt flow rate is tested according to GB / T 3682.1-2018.

[0122] The performance tests of the nylon 6 materials prepared in Examples 1-3 and Comparative Examples 1-3 were conducted according to the above standards, and the results are as follows:

[0123]

[0124] The test results demonstrate that the modified nylon 6 material of the present invention significantly outperforms unmodified nylon 6 and nylon 6 materials containing only a single modifying component in terms of water absorption, low-temperature impact resistance, mechanical properties, and processability. In particular, Example 2 exhibits the best overall performance, with the lowest water absorption, the highest low-temperature impact strength and tensile strength, and significantly improved flexural modulus and melt flow rate.

[0125] To further verify the weather resistance of the modified nylon 6 material, long-term ultraviolet (UV) aging testing was conducted. The nylon 6 materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to 1000 hours of UV aging testing using a QUV accelerated aging test chamber, simulating the performance changes that occur when the materials are exposed to UV light outdoors for a long time. Following the testing, the materials' tensile strength and flexural modulus retention were measured, with the following results:

[0126]

[0127] The data in the table demonstrates that after 1000 hours of QUV testing, the modified nylon 6 material of the present invention significantly outperforms unmodified nylon 6 and nylon 6 containing only a single modifying component in terms of tensile strength and flexural modulus retention. In particular, Example 2 achieved a tensile strength retention of 85.71% and a flexural modulus retention of 88.2%, demonstrating excellent weather resistance.

[0128] In contrast, after UV aging testing under the same conditions, the tensile strength and flexural modulus of unmodified nylon 6 decreased by approximately 41.56% and 38.75%, respectively, indicating a significant degradation of performance. This is primarily because the molecular chains of unmodified nylon 6 are more susceptible to breakage and degradation under the influence of UV rays, resulting in a significant decrease in the material's mechanical properties. However, the modified nylon 6 with the addition of nano-titanium dioxide and the compatibilizer POE-g-MAH effectively mitigates the degradation of nylon 6 by UV rays due to the UV shielding effect of the nano-titanium dioxide and the optimization of the material's internal structure by the compatibilizer, thereby maintaining high mechanical properties.

[0129] Furthermore, while nylon 6 materials containing only nano-titanium dioxide or only the compatibilizer POE-g-MAH improved weather resistance to a certain extent, their performance retention was still lower than that of the modified material of the present invention. This suggests that the synergistic effect of nano-titanium dioxide and the compatibilizer POE-g-MAH is crucial for improving the weather resistance of nylon 6.

[0130] In summary, the modified nylon 6 material of the present invention not only performs well in terms of water absorption, low-temperature impact resistance, mechanical properties and processing performance, but also has significant advantages in the retention rate of mechanical properties after long-term UV aging. It can better meet the needs of application scenarios with high requirements on material weather resistance, such as outdoor equipment housings and automobile engine peripheral components.

Claims

1. A modified nylon 6 material, made from the following raw materials in parts by weight: Nylon 6 chips: 80-95 parts Nano titanium dioxide: 2-5 parts Silane coupling agent: 0.1-0.5 parts Antioxidant: 0.5-1 part Lubricant: 0.3-0.8 parts Compatibilizer: 3-8 parts in, The mass ratio of nano-titanium dioxide to silane coupling agent is 1:0.05-0.1, and the nano-titanium dioxide and silane coupling agent are reacted to obtain silane coupling agent-modified nano-titanium dioxide, which is then mixed with nylon 6 chips; The compatibilizer is maleic anhydride grafted ethylene-octene copolymer POE-g-MAH.

2. The modified nylon 6 material according to claim 1, wherein The total weight of nylon 6 chips, nano titanium dioxide, silane coupling agent, antioxidant, lubricant and compatibilizer is 100 parts.

3. The modified nylon 6 material according to claim 1, wherein The nano titanium dioxide is nano titanium dioxide particles with a particle size of 20-50 nm.

4. The modified nylon 6 material according to claim 1, wherein Silane coupling agent has the structure shown below: (AND) m -R-Si-(X)3, in, m is 1 or 2; Y is selected from amino (-NH2), epoxy, hydroxyl, and thiol; R is selected from a divalent or trivalent C2 to C10 alkyl group or a group in which one or more carbon atoms in the middle of the alkyl group are replaced by O or N; preferably, R is selected from a C3 to C6 alkylene group, -(CH2)2NH(CH2)3-, (CH2)3NH(CH2)2NH(CH2)2, (CH2)3N(CH2CH2-)2, CHO(CH2)3; At least one X is a C1 to C4 alkoxy group, and the remaining Xs are independently selected from C1 to C4 alkoxy and C1 to C4 alkoxy groups, preferably at least one X is selected from methoxy or ethoxy, and the remaining Xs are independently selected from methyl, ethyl, methoxy, and ethoxy groups; In particular, the silane coupling agent is selected from aminosilane coupling agents, epoxysilane coupling agents, and mercaptosilane coupling agents; More particularly, the aminosilane coupling agent is selected from KH-540, KH-550, KH-792, Si-550, Si-602, Si-603, Si-902; the epoxysilane coupling agent is selected from KH-560, KH-561, KH-562; and the mercaptosilane coupling agent is selected from KH-580, KH-590.

5. The modified nylon 6 material according to claim 1, wherein The reaction of the silane coupling agent and the nano-titanium dioxide is carried out as follows: the nano-titanium dioxide and the silane coupling agent are mixed in a mass ratio of 1:0.05-0.1, and stirred at 60-80° C. for reaction for 2-4 hours.

6. The modified nylon 6 material according to claim 1, wherein The antioxidant is selected from one or more combinations of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants; Particularly, the hindered phenol antioxidant is selected from antioxidant 1010 and di-tert-butyl-p-cresol; and the phosphite antioxidant is selected from antioxidant 168.

7. The modified nylon 6 material according to claim 1, wherein The lubricant is selected from one or more combinations of fatty acids and their salts, fatty acid esters, silicone oils, and polyethylene glycol lubricants; in particular, one or more combinations selected from zinc stearate, glycerol monostearate, polydimethylsiloxane (PDMS) or PEG 6000.

8. The method for preparing the modified nylon 6 material according to any one of claims 1 to 7, comprising the following steps: (1) Dry nylon 6 chips at 80-100°C for 4-6 hours; (2) mixing nano-titanium dioxide and a silane coupling agent in a mass ratio of 1:0.05-0.1, stirring and reacting at 60-80° C. for 2-4 hours to obtain modified nano-titanium dioxide; (3) Add the dried nylon 6 chips, modified nano-titanium dioxide, antioxidant, lubricant and compatibilizer into a high-speed mixer and mix at 110-130° C. for 5-10 minutes; (4) The mixed material is melt-extruded through a twin-screw extruder at an extrusion temperature of 220-260° C. and a screw speed of 300-500 r / min. After extrusion, the material is cooled and pelletized to obtain modified nylon 6 particles.

9. A product comprising the modified nylon 6 material according to any one of claims 1 to 7.

10. The product according to claim 9, which is selected from automobile engine parts and peripheral components, mechanical gears, insulation materials for wires and cables, housings of household appliances, and housings of outdoor equipment.

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