Low-warpage glass fiber reinforced nylon composite material and preparation method thereof

Abstract

The invention provides a low-warpage glass fiber reinforced nylon composite material and a preparation method thereof. The low-warpage glass fiber reinforced nylon composite material comprises 40-60 parts of PA6 resin; 20 to 30 parts of glass fiber; 0-20 parts of transparent nylon; 0.5 to 1.5 parts of two-phase nano particles; 0.2 to 0.4 part of an antioxidant; 0.2 to 0.5 part of a lubricant; 0.1 to 0.5 part of a nucleating agent; wherein the two-phase nano particle has a shell-core structure, the core of the two-phase nano particle is SiO2, the shell layer of the two-phase nano particle is modified polysiloxane, and the surface of the shell layer is grafted with a bifunctional group containing an amino group and a hydroxyl group. Benefited from the synergistic effect of the core-shell structure and the surface bifunctional group of the two-phase nano particles, the two-phase nano particles are uniformly dispersed in the nylon matrix, and good interface bonding is formed; and meanwhile, the combined structure of the rigid core and the flexible shell layer effectively adjusts the internal stress distribution of the material, reduces anisotropic shrinkage caused by glass fiber orientation, and remarkably improves the dimensional stability and mechanical properties of the composite material.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a low-warpage glass fiber reinforced nylon composite material and its preparation method. Background Technology

[0002] Glass fiber reinforced nylon materials are widely used in the automotive industry due to their excellent mechanical properties, heat resistance, chemical corrosion resistance, and good processability. They are commonly used to manufacture automotive engine parts, interior parts, and exterior parts. However, glass fiber reinforced nylon composites still face the problem of severe warping deformation in practical applications. This is mainly due to factors such as anisotropic shrinkage caused by glass fiber orientation and poor interfacial compatibility between glass fiber and the nylon matrix.

[0003] Currently, various technical solutions have been developed in the industry to address the warpage problem of glass fiber reinforced nylon composites. For example, CN113943435B discloses a flame-retardant, low-warpage, solder-resistant nylon glass fiber reinforced composite material. This material uses glass fibers with an elliptical cross-section and adds components such as molybdenum disulfide and brominated polystyrene to improve the material's warpage performance. CN116790119A discloses a high-performance, low-warpage, halogen-free, flame-retardant reinforced PA66 composite material. By adding long-chain carbon nylon resin and modified mica powder, a network structure with mica as crosslinking points is formed, restricting the molecular motion of the nylon resin and thus reducing the shrinkage problem caused by glass fiber orientation.

[0004] However, existing technologies still have the following shortcomings: 1. In existing glass fiber reinforced nylon composites, the interfacial compatibility between glass fiber and nylon matrix is ​​still not ideal, resulting in weak interfacial bonding and easy occurrence of "floating fiber" phenomenon, which affects the appearance and mechanical properties of the material.

[0005] 2. Traditional modification methods, such as adding coupling agents and surface treatment, can improve interfacial bonding to some extent, but their effects are limited for composite materials with high glass fiber content and cannot fundamentally solve the warping problem.

[0006] 3. The fillers used in the existing technology are mostly of a single structure, which makes it difficult to achieve good compatibility with the matrix and effective control of material properties at the same time. In particular, there are challenges in improving the material's warpage performance while keeping other properties unaffected.

[0007] Therefore, there is an urgent need to develop a new type of low-warpage glass fiber reinforced nylon composite material. Through innovative material design and formulation optimization, the warpage problem of glass fiber reinforced nylon composite materials can be solved at the molecular and nanoscale levels, while maintaining or improving the overall performance of the material. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a low-warpage glass fiber reinforced nylon composite material to solve the problem of high warpage in the prior art of glass fiber reinforced nylon materials. At the same time, this invention will also provide a method for preparing the low-warpage glass fiber reinforced nylon composite material.

[0009] To achieve the above and other related objectives, the present invention provides the following technical solutions: A first aspect of the present invention provides a low-warpage glass fiber reinforced nylon composite material, comprising the following components in parts by weight: 40-60 parts of PA6 resin; 20-30 parts glass fiber; 10-20 parts transparent nylon; 0.5-1.5 parts of biphase nanoparticles; Antioxidant 0.2-0.4 parts; Lubricant 0.2-0.5 parts; Nucleating agent 0.1-0.5 parts.

[0010] The biphase nanoparticles have a core-shell structure, with the core being a rigid SiO2 and the shell being a flexible modified polysiloxane. The shell surface is grafted with bifunctional groups containing amino and hydroxyl groups.

[0011] The flexible polysiloxane shell absorbs the shrinkage stress between the glass fiber and the PA6 matrix during material curing, reducing anisotropic shrinkage caused by glass fiber orientation, homogenizing stress, and thus reducing warpage. Furthermore, the biphase nanoparticles interfere with the directional alignment of the glass fiber during melt flow, reducing anisotropy after molding and further minimizing warpage. The surface of the biphase nanoparticles is grafted with amino and hydroxyl groups; the amino groups form hydrogen bonds with nylon, and the hydroxyl groups form covalent bonds with the silanol groups on the glass fiber surface, constructing "molecular bridges" and enhancing interfacial bonding. Simultaneously, the flexible polysiloxane shell can "wrap" the glass fiber surface, filling the micro-gaps between the glass fiber and the matrix, forming a physical anchor and reducing failure caused by glass fiber delamination. Moreover, the flexible polysiloxane shell induces crazes and shear bands under stress, absorbing impact energy and increasing the notched impact strength of the material by 20%-50% while only decreasing the elastic modulus by about 5%.

[0012] Furthermore, the core diameter is 15-20 nm; the shell thickness is 4-6 nm.

[0013] Furthermore, the molar ratio of amino to hydroxyl groups on the shell surface is 1:1-1.5; preferably 1:1.2-1.5.

[0014] In one embodiment of the present invention, the biphase nanoparticles are obtained by the following preparation method: (1) Preparation of precursor: Tetraethyl orthosilicate (TEOS) is mixed with anhydrous ethanol, and hydrochloric acid is added as a catalyst to hydrolyze and form silica sol; (2) Core formation: SiO2 cores are obtained after silica sol gelation and drying; (3) Shell construction: The SiO2 core reacts with γ-aminopropyltriethoxysilane (APTES) and γ-glycidoxypropyltrimethoxysilane (GPTMS) to form a modified polysiloxane shell; (4) Surface bifunctionalization: The product reacts with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) to introduce amino and epoxy groups, and finally hydrolyzes to form hydroxyl groups.

[0015] Furthermore, in step (1), the volume ratio of TEOS to anhydrous ethanol is 1:(3-5); preferably 1:4.

[0016] Furthermore, in step (1), the hydrochloric acid concentration is 0.01 mol / L, and the pH is adjusted to be between 5.5 and 6.5.

[0017] Furthermore, in step (1), the reaction temperature is 25℃±2℃; the reaction time is 2-4h.

[0018] Furthermore, in step (2), the gelation temperature is 60℃±2℃; the gelation time is 4-6h.

[0019] Furthermore, in step (2), the drying temperature is 120°C and the drying time is 6-8 hours.

[0020] Furthermore, in step (3), the molar ratio of APTES to GPTMS is 1:(0.5-1); preferably 3:2.

[0021] Furthermore, in step (3), the reaction temperature is 80℃±2℃; the reaction time is 6-8h.

[0022] Furthermore, in step (3), the reaction is carried out under an inert atmosphere.

[0023] Furthermore, in step (4), the product of step (3) is reacted with AEAPTMS at 75°C for 3 hours to introduce an amino functional group; then it is reacted with GPTMS for 2 hours to introduce an epoxy group, and finally hydrolyzed to form a hydroxyl group.

[0024] In one embodiment of the present invention, the relative viscosity of the PA6 resin is 2.5.

[0025] In one embodiment of the present invention, the transparent nylon is selected from one or a combination of PA6I, PA6I / 6T.

[0026] In one embodiment of the present invention, the glass fiber comprises chopped glass fibers and glass microspheres, and the glass fiber is surface treated.

[0027] In one embodiment of the present invention, the antioxidant is selected from one or a combination of several of hindered phenols, amines, and phosphites.

[0028] Furthermore, the antioxidant is a complex of hindered phenols, amines, and phosphites.

[0029] In one embodiment of the present invention, the nucleating agent is selected from one or a combination of several inorganic nucleating agents and organic nucleating agents.

[0030] In one embodiment of the present invention, the glass fiber reinforced nylon composite material further includes 1 part of black masterbatch; the black masterbatch is carbon black masterbatch of nylon carrier.

[0031] A second aspect of the present invention provides a method for preparing a low-warpage glass fiber reinforced nylon composite material, comprising the following steps: S1. Weigh each raw material according to the proportions; S2. Add all raw materials except glass fiber into a high-speed mixer and stir evenly to obtain a premix. S3. The premixed material is fed into the twin-screw extruder through the main feed port, and the glass fiber is fed from the side feed port for melt extrusion. S4. The extruded molten material is drawn into strips, cooled with water, and pelletized to obtain the low-warpage glass fiber reinforced nylon composite material.

[0032] Furthermore, the temperature of each zone of the twin-screw extruder is 220℃-250℃, and the screw speed is 500-600 rpm.

[0033] As described above, the low-warpage glass fiber reinforced nylon composite material and its preparation method of the present invention have the following beneficial effects: 1. In the low-warpage glass fiber reinforced nylon composite material of the present invention, the flexible polysiloxane shell of the biphase nanoparticles can effectively absorb the shrinkage stress between the glass fiber and the PA6 matrix, reduce the anisotropic shrinkage caused by the orientation of the glass fiber, and homogenize the stress, thereby significantly reducing warpage; at the same time, the biphase nanoparticles interfere with the directional arrangement of the glass fiber in the melt flow, reduce the anisotropy after molding, and further reduce warpage.

[0034] 2. The amino groups grafted onto the surface of the biphase nanoparticles of the present invention form hydrogen bonds with nylon, and the hydroxyl groups form covalent bonds with the silanol groups on the glass fiber surface, thus constructing a "molecular bridge" and enhancing the interfacial bonding force. At the same time, the flexible polysiloxane shell can "wrap" the glass fiber surface, fill the micro gaps between the glass fiber and the matrix, form a physical anchor, and reduce failure caused by glass fiber peeling.

[0035] 3. The flexible polysiloxane shell in biphase nanoparticles can induce crazes and shear bands when subjected to stress, effectively absorbing impact energy and increasing the notched impact strength of the material by 20%-50%.

[0036] 4. The present invention exhibits significant low warpage performance. Through a rationally proportioned component design, the shrinkage rate of the material is effectively reduced, warpage deformation during the molding process is minimized, and the dimensional accuracy and appearance quality of the finished product are improved. Under standard testing conditions, the warpage of a 200mm×200mm×2mm standard plate prepared from the material of the present invention is less than 0.5mm, while the warpage of traditional glass fiber reinforced nylon materials is typically 1.5-2.5mm.

[0037] 5. The surface-modified glass fiber in the material of this invention has good bonding force with the nylon matrix. At the same time, under the synergistic effect of antioxidants, lubricants and nucleating agents, the material maintains excellent mechanical properties and heat resistance while having low warpage characteristics.

[0038] 6. The preparation process of this invention is simple and can be completed using a conventional twin-screw extruder and processing technology. No special equipment or complex processes are required, which facilitates industrial production and widespread application. Detailed Implementation

[0039] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0040] Example 1 A low-warpage glass fiber reinforced nylon composite material comprises the following components in parts by weight: 60 parts PA6 resin, 30 parts glass fiber, 10 parts transparent nylon, 1 part biphasic nanoparticles, 0.4 parts antioxidant, 0.5 parts lubricant, 0.2 parts nucleating agent, and 1 part black masterbatch.

[0041] The biphase nanoparticles in this composite material have a core-shell structure, with a rigid SiO2 core and a flexible modified polysiloxane shell. The shell surface is grafted with bifunctional groups containing amino and hydroxyl groups. The core diameter is 18 nm, and the shell thickness is 5 nm. This unique core-shell structure enables the nanoparticles to form a good interfacial bond within the nylon matrix, providing both rigid support and flexible cushioning, effectively improving the mechanical properties and dimensional stability of the composite material.

[0042] These biphase nanoparticles were prepared through the following steps: (1) Precursor preparation: Tetraethyl orthosilicate (TEOS) and anhydrous ethanol were mixed at a volume ratio of 1:4, and a small amount of 0.01 mol / L hydrochloric acid was added as a catalyst to adjust the pH to between 5.5 and 6.5. After stirring and hydrolyzing at 25°C for 2 hours, a silica sol was formed. In this step, anhydrous ethanol provided a good reaction environment as a solvent, and the hydrochloric acid catalyst accelerated the hydrolysis process of TEOS.

[0043] (2) Core formation: The silica sol obtained in step (1) was gelled at 60°C for 4 hours, and then dried at 120°C for 8 hours to obtain SiO2 cores. During the gelation process, the silica groups in the sol gradually condensed to form a three-dimensional network structure, and finally formed SiO2 core particles with a certain particle size.

[0044] (3) Shell construction: The SiO2 core obtained in step (2) was dispersed in toluene, and a mixture of 3-aminopropyltriethoxysilane (APTES) and 3-glycidylpropyltrimethoxysilane (GPTMS) (molar ratio 3:2) was added. The mixture was reacted at 80°C for 6 hours under nitrogen protection to form a modified polysiloxane shell with a thickness of about 5 nm. APTES provides amino functional groups, and GPTMS provides epoxy functional groups. The two work together to form a polysiloxane network structure with specific functional groups.

[0045] (4) Surface bifunctionalization: The product of step (3) was reacted with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS) at 75°C for 3 hours to introduce an amino functional group; then it was reacted with GPTMS for 2 hours to introduce an epoxy group; finally, the epoxy group was converted into a hydroxyl group through hydrolysis to achieve bifunctionalization. This step enables the nanoparticle surface to have both amino and hydroxyl functional groups, which enhances the compatibility with the nylon matrix and the interfacial bonding strength.

[0046] Furthermore, the glass fiber comprises a mixture of 25 parts chopped glass fibers and 5 parts glass microspheres, and these glass fibers are surface-treated with a silane coupling agent. The surface-treated glass fibers exhibit better interfacial bonding with the nylon matrix, reducing stress concentration and improving the overall mechanical properties of the composite material. The chopped glass fibers primarily provide reinforcement, while the glass microspheres help improve the isotropy of the material and reduce warpage.

[0047] Furthermore, the antioxidants selected are a combination of hindered phenolic antioxidants, amine antioxidants, and phosphite antioxidants. The three antioxidants work synergistically to effectively prevent the oxidative degradation of the composite material during high-temperature processing and use, thus extending the material's service life.

[0048] The method for preparing this low-warpage glass fiber reinforced nylon composite material is as follows: S1. Weigh each raw material according to the proportions; S2. Add all raw materials except glass fiber into a high-speed mixer and stir evenly to obtain a premix. S3. The premixed material is fed into the twin-screw extruder through the main feed port, and the glass fiber is fed from the side feed port for melt extrusion. S4. The extruded molten material is pulled, cooled with water, and pelletized to obtain the low-warpage glass fiber reinforced nylon composite material.

[0049] Example 2 This embodiment provides a low-warpage glass fiber reinforced nylon composite material, which differs from Example 1 only in that the amount of biphase nanoparticles added is 0.5 parts.

[0050] Example 3 This embodiment provides a low-warpage glass fiber reinforced nylon composite material, which differs from Example 1 only in that the amount of biphase nanoparticles added is 1.5 parts.

[0051] Example 4 This embodiment provides a low-warpage glass fiber reinforced nylon composite material, which differs from Embodiment 1 only in that: the glass fiber includes a mixture of 20 parts chopped glass fiber and 10 parts glass microspheres, and these glass fibers are surface treated with a silane coupling agent.

[0052] Comparative Example 1 This comparative example provides a low-warpage glass fiber reinforced nylon composite material, which differs from Example 1 only in that: no biphase nanoparticles are added.

[0053] Performance test results

[0054] Experimental data show that, thanks to the synergistic effect of the core-shell structure and surface bifunctional groups of the biphase nanoparticles, the nanoparticles are uniformly dispersed in the nylon matrix, forming a good interfacial bond. Simultaneously, the combined structure of the rigid core and flexible shell effectively regulates the internal stress distribution of the material, reduces anisotropic shrinkage caused by glass fiber orientation, and significantly improves the dimensional stability and mechanical properties of the composite material. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial applicability.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A low-warpage glass fiber reinforced nylon composite material, characterized in that, The components include the following parts by weight: 40-60 parts of PA6 resin; 20-30 parts glass fiber; 0-20 parts transparent nylon; 0.5-1.5 parts of biphase nanoparticles; Antioxidant 0.2-0.4 parts; Lubricant 0.2-0.5 parts; Nucleating agent 0.1-0.5 parts; The biphase nanoparticles have a core-shell structure, with SiO2 as the core and modified polysiloxane as the shell, the surface of which is grafted with bifunctional groups containing amino and hydroxyl groups.

2. The low-warpage glass fiber reinforced nylon composite material according to claim 1, characterized in that, The core diameter is 15-20 nm; the shell thickness is 4-6 nm.

3. The low-warpage glass fiber reinforced nylon composite material according to claim 1, characterized in that, The biphase nanoparticles were obtained by the following preparation method: (1) Preparation of precursor: TEOS is mixed with anhydrous ethanol and hydrochloric acid is added as a catalyst to hydrolyze and form silica sol; (2) Core formation: SiO2 cores are obtained after silica sol gelation and drying; (3) Shell construction: The SiO2 core reacts with APTES and GPTMS to form a modified polysiloxane shell; (4) Surface bifunctionalization: The product reacts with AEAPTMS and GPTMS to introduce amino and epoxy groups, and finally hydrolyzes to form hydroxyl groups.

4. The low-warpage glass fiber reinforced nylon composite material according to claim 3, characterized in that, In step (1), the volume ratio of TEOS to anhydrous ethanol is 1:(3-5).

5. The low-warpage glass fiber reinforced nylon composite material according to claim 3, characterized in that, In step (2), the gelation temperature is 60℃±2℃; the gelation time is 4-6h.

6. The low-warpage glass fiber reinforced nylon composite material according to claim 3, characterized in that, In step (3), the molar ratio of APTES to GPTMS is 1:(0.5-1).

7. The low-warpage glass fiber reinforced nylon composite material according to claim 3, characterized in that, In step (4), the product of step (3) is reacted with AEAPTMS at 75°C for 3 hours to introduce an amino functional group; then it is reacted with GPTMS for 2 hours to introduce an epoxy group, and finally hydrolyzed to form a hydroxyl group.

8. The low-warpage glass fiber reinforced nylon composite material according to claim 1, characterized in that, The glass fiber comprises chopped glass fibers and glass microspheres, and the glass fiber is surface treated.

9. The low-warpage glass fiber reinforced nylon composite material according to claim 1, characterized in that, The antioxidant is selected from one or a combination of several of hindered phenols, amines, and phosphites.

10. A method for preparing a low-warpage glass fiber reinforced nylon composite material as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Weigh each raw material according to the proportions; S2. Add all raw materials except glass fiber into a high-speed mixer and stir evenly to obtain a premix. S3. The premixed material is fed into the twin-screw extruder through the main feed port, and the glass fiber is fed from the side feed port for melt extrusion. S4. The extruded molten material is pulled, cooled with water, and pelletized to obtain the low-warpage glass fiber reinforced nylon composite material.

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