A high-toughness wear-resistant polystyrene composite material for non-metallic additive manufacturing and a preparation method thereof

Abstract

This invention belongs to the field of non-metallic additive manufacturing materials technology, and provides a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing and its preparation method. The composite material includes a polystyrene matrix resin, a wear-resistant and toughening functional masterbatch, and processing aids. The wear-resistant and toughening functional masterbatch is formed by pre-melting and compounding maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, acicular wollastonite treated with a silane coupling agent, polytetrafluoroethylene micropowder, and styrene-maleic anhydride copolymer. In preparation, acicular wollastonite is first treated with a silane coupling agent, then the treated acicular wollastonite, polytetrafluoroethylene micropowder, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, and styrene-maleic anhydride copolymer are melt-combined to form a masterbatch, which is then re-melted and blended with the polystyrene matrix resin and processing aids, and extruded into filaments. This invention improves the dispersion state of wear-resistant fillers and toughening components in the polystyrene matrix resin, and enhances the interlayer bonding performance, impact resistance, and wear resistance of the printed parts.

Description

Technical Field

[0001] This invention belongs to the field of non-metallic additive manufacturing materials technology, and relates to a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing and its preparation method. Background Technology

[0002] Polystyrene is characterized by its ease of molding and processing, good dimensional stability, and low material cost, making it suitable for fused deposition modeling (FDM) filaments. However, the high rigidity of polystyrene molecular chains results in insufficient toughness when used alone as a printing material, leading to brittle cracking of printed parts under impact or interlayer stretching. Furthermore, polystyrene itself has limited wear resistance and load-bearing capacity, which can accelerate wear when applied to wear-resistant structural components. Therefore, to balance wear resistance and toughness, existing polystyrene-based FDM filaments typically require the simultaneous introduction of hard wear-resistant fillers and elastomer toughening components.

[0003] However, when both rigid wear-resistant fillers and elastomer toughening components are added to polystyrene composites, the interfacial compatibility between the rigid fillers and the polystyrene matrix resin is limited. Direct blending easily leads to filler agglomeration, insufficient interfacial wetting, and uneven local dispersion. When the elastomer toughening component and inorganic filler are added separately, their dispersion in the polystyrene matrix resin is difficult to control synchronously. Local filler agglomeration and uneven elastomer distribution increase melt flow fluctuations and affect the diameter stability of the extruded filaments.

[0004] During fused deposition modeling (FDM), filler agglomeration zones and incompatible interfacial areas can affect the contact between adjacent melt channels and the diffusion of polystyrene segments, potentially becoming crack initiation sites during stress and friction in the printed part. Insufficient interfacial bonding between the filler and the matrix resin also increases filler detachment and material mass loss during friction. Therefore, existing polystyrene-based additive manufacturing materials still suffer from uneven dispersion of wear-resistant fillers, insufficient interfacial bonding between fillers and the matrix resin, and the difficulty in simultaneously achieving both wear resistance and impact resistance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing and its preparation method. The method first treats acicular wollastonite with a silane coupling agent, then melt-composites the treated acicular wollastonite, polytetrafluoroethylene micro powder, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, and styrene-maleic anhydride copolymer to form a wear-resistant and toughening functional masterbatch. Subsequently, the wear-resistant and toughening functional masterbatch is melt-blended again with polystyrene matrix resin and processing aids and extruded into filaments.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing, the composite material being used for melt deposition molding, the composite material comprising a polystyrene matrix resin, a wear-resistant and toughening functional masterbatch, and processing aids;

[0008] The mass ratio of the polystyrene matrix resin, the wear-resistant and toughening functional masterbatch, and the processing aid is 100:(18-55):(0.6-2.3).

[0009] The polystyrene matrix resin includes general-purpose polystyrene and high-impact polystyrene;

[0010] The wear-resistant and toughening functional masterbatch is a particle formed by pre-melting and compounding maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and needle-shaped wollastonite pretreated with silane coupling agent.

[0011] Preferably, the mass ratio of the general-purpose polystyrene to the high-impact polystyrene is 1:(0.3-1.0).

[0012] Preferably, the melt flow rate of the general-purpose polystyrene under the conditions of GB / T 3682, 200℃, and 5kg is 6-10g / 10min, and the melt flow rate of the high-impact polystyrene under the conditions of GB / T 3682, 200℃, and 5kg is 3.5-5.5g / 10min.

[0013] Preferably, in the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, acicular wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer and silane coupling agent is 100:(60-140):(10-43):(6-29):(0.5-4.3).

[0014] Preferably, the acicular wollastonite has an aspect ratio of 7-25 and a particle size of 600-1250 mesh; the polytetrafluoroethylene micro powder has a D50 particle size of 3.0-8.0 μm.

[0015] Preferably, the mass ratio of the needle-shaped wollastonite to the polytetrafluoroethylene micro powder is 1:(0.1-0.5).

[0016] Preferably, the melt flow rate of the maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer at 190°C and 2.16 kg is 3–9 g / 10 min.

[0017] Preferably, the styrene-maleic anhydride copolymer has an acid value of 470-500 mg KOH / g, a number-average molecular weight of 1800-2200, and a weight-average molecular weight of 5000-6000.

[0018] Preferably, the processing aids include antioxidants and lubricants; the antioxidants include antioxidant 1010 and / or antioxidant 168; the lubricants include one or more of ethylene bis-stearamide, zinc stearate, and polyethylene wax.

[0019] Preferably, the composite material is a filament for fused deposition modeling, and the diameter of the filament is 1.75±0.05mm or 2.85±0.05mm.

[0020] In a second aspect, the present invention provides a method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing as described in the first aspect, comprising the following steps:

[0021] S1, add silane coupling agent to a mixed solution of ethanol and water to obtain silane treatment solution, premix the silane treatment solution with needle-shaped wollastonite and polytetrafluoroethylene micro powder and then dry to obtain pretreated wear-resistant filler.

[0022] S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer and the pretreated wear-resistant filler are melt-composite granulated to obtain wear-resistant and toughening functional masterbatch;

[0023] S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules;

[0024] S4, the composite material granules are extruded into filaments to obtain polystyrene composite material filaments for melt deposition molding.

[0025] Preferably, in S1, the silane coupling agent is any one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0026] Preferably, in S2, the melt composite granulation is carried out using a mixer or a twin-screw extruder, the melt composite temperature is 170-210℃, and the screw speed or rotor speed is 60-250 rpm.

[0027] Preferably, in S3, the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding, and the general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding; the secondary melt blending temperature is 175-220℃, and the screw speed is 100-250rpm.

[0028] Preferably, in S4, the extrusion filaments are formed using a single-screw extruder or a twin-screw extrusion filaments equipment, with an extrusion temperature of 180-230℃ and a traction speed of 2-10m / min. The extruded filaments are then cooled, measured in diameter, and wound up.

[0029] When a silane coupling agent is added to a mixed solution of ethanol and water, the alkoxy groups in the silane molecules hydrolyze to form silanol groups. The surface of acicular wollastonite contains silanol groups, adsorbed hydroxyl groups, and other polar sites. These silanol groups can condense with these surface polar sites or form hydrogen bonds and adsorption. During drying, some silanol groups further condense, and silane molecules adhere to the surface of the acicular wollastonite. This reduces the inorganic polarity of the acicular wollastonite surface, increasing its wettability and affinity for organic polymers. Silane coupling agent treatment also reduces the mutual attraction between acicular wollastonite particles due to their high surface polarity and surface energy, thus reducing agglomeration of the acicular wollastonite during subsequent melt-compositing processes.

[0030] The interfacial interactions between the organic end groups of different silane coupling agents and other components in the system vary. The surface of acicular wollastonite treated with γ-aminopropyltriethoxysilane contains amino groups, which can interact with the maleic anhydride groups in maleic anhydride-grafted styrene-ethylene / butene-styrene copolymers and styrene-maleic anhydride copolymers, and can undergo anhydride ring-opening reactions under molten conditions. The surface of acicular wollastonite treated with γ-glycidoxypropyltrimethoxysilane contains epoxy groups, which can interact with hydroxyl, carboxyl, and other polar groups in the system, and can also undergo epoxy ring-opening reactions under appropriate reaction conditions. The surface of acicular wollastonite treated with γ-methacryloyloxypropyltrimethoxysilane has an organic methacryloyloxy structure, which mainly improves the wettability and organic affinity of the acicular wollastonite surface to styrene polymers. Without the addition of a free radical initiator, the interaction between the methacryloyloxy structure and the maleic anhydride groups is not described as a defined covalent reaction.

[0031] Polytetrafluoroethylene (PTFE) micropowder has low surface energy and strong surface chemical inertness, and does not undergo a major chemical coupling reaction with silane coupling agents. Therefore, this invention first treats acicular wollastonite with a silane coupling agent, and then premixes the treated acicular wollastonite with PTFE micropowder. During the premixing process, the acicular wollastonite and PTFE micropowder form a relatively uniform wear-resistant filler mixture under mechanical shearing and particle collision, reducing the probability of local concentration differences when the two fillers are added separately to the molten system. The PTFE micropowder does not melt and flow at the subsequent melting and compounding temperature, and is mainly dispersed in the polymer melt as solid particles.

[0032] Maleic anhydride-grafted styrene-ethylene / butene-styrene copolymers comprise styrene segments, ethylene / butene soft segments, and maleic anhydride polar groups. The styrene segments exhibit good compatibility with the styrene phase in general-purpose polystyrene and high-impact polystyrene, and can interdiffusion and entangle with the polystyrene segments during melt blending. The ethylene / butene soft segments have a low glass transition temperature, enabling elastic deformation and absorption of some deformation energy under impact or tensile loads. The maleic anhydride polar groups increase the polar interaction between the maleic anhydride-grafted copolymer and the treated acicular wollastonite surface, improving the wetting of the acicular wollastonite surface by the polymer melt.

[0033] The styrene-maleic anhydride copolymer contains both styrene and maleic anhydride structural units. The styrene structural units are structurally similar to the polystyrene matrix resin, while the maleic anhydride structural units have high polarity, which increases the wetting and interfacial interaction of the system on the treated acicular wollastonite surface. The styrene-maleic anhydride copolymer is distributed between the polystyrene phase, the maleic anhydride-grafted elastomer, and the treated acicular wollastonite, reducing the difference in interfacial properties between the inorganic filler surface and the non-polar polystyrene matrix resin. Both the maleic anhydride-grafted elastomer and the styrene-maleic anhydride copolymer contain maleic anhydride groups. The interaction between them mainly includes compatibility between styrene segments, interaction between polar groups, and physical entanglement in the molten state; the interaction is not limited to a necessary covalent chemical reaction.

[0034] In the preparation of the wear-resistant and toughening functional masterbatch, the treated acicular wollastonite, polytetrafluoroethylene (PTFE) micropowder, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, and styrene-maleic anhydride copolymer are first melt-composite. Compared with directly adding a large amount of polystyrene matrix resin to each component, the local concentration of wear-resistant filler is higher in the masterbatch preparation stage. The filler can fully contact the maleic anhydride-grafted elastomer and styrene-maleic anhydride copolymer under strong melt shear. Melt shear breaks down the loose agglomerate structure between the acicular wollastonite and PTFE micropowder, allowing the polymer melt to enter the interparticle gaps and wet the filler surface, thus improving the uniformity of filler distribution in the masterbatch.

[0035] The masterbatch preparation process establishes a pre-dispersion state between the wear-resistant filler and toughening components, but does not limit the internal structure of the masterbatch to a fixed coating layer or fixed composite particles that remain intact after secondary melt blending. After the masterbatch enters the polystyrene matrix resin, it undergoes dilution, dispersion, and morphology adjustment under the shearing action of secondary melt. The pre-formed filler wetting state helps reduce the re-agglomeration of needle-like wollastonite and polytetrafluoroethylene micropowder during the secondary blending process. Maleic anhydride-grafted elastomer and styrene-maleic anhydride copolymer enter the polystyrene melt together with the masterbatch, reducing local compositional fluctuations caused by the separate addition of fillers and interface conditioning components at different feeding positions.

[0036] General-purpose polystyrene possesses high stiffness and good melt flowability, while high-impact polystyrene contains a rubber toughening phase. When these two components together form the polystyrene matrix resin, general-purpose polystyrene provides the primary rigidity, dimensional stability, and flowability, while the rubber phase in high-impact polystyrene provides additional impact energy dissipation capacity. Maleic anhydride-grafted styrene-ethylene / butene-styrene copolymers further increase the elastic deformation component in the system. This elastic deformation component, together with the rubber phase in high-impact polystyrene, shares the burden of deformation and energy dissipation under impact loads.

[0037] Needle-shaped wollastonite possesses a high aspect ratio and inorganic rigidity. Under stress, the needle-shaped wollastonite dispersed within the polystyrene matrix resin can bear part of the load and obstruct and deflect crack propagation paths. When the interfacial bonding between needle-shaped wollastonite and the polystyrene matrix resin is insufficient, stress concentration easily occurs at the ends of the needle-shaped particles and in particle agglomeration areas, potentially causing cracks to propagate along the interface between the filler and the matrix resin. After treatment with a silane coupling agent and pre-melt-composite with interface-modifying components, the wetting state and interfacial bonding of the needle-shaped wollastonite surface are improved, reducing the probability of filler-induced matrix cracking at the filler ends and filler pull-out from the matrix.

[0038] When printed parts are subjected to impact or Z-axis tensile loads, cracks initially form in the polystyrene matrix resin, interlaminar fusion regions, or localized defect areas. As cracks propagate near the needle-like wollastonite, the needle-like particles alter the local stress distribution and increase the tortuosity of the crack path. When cracks propagate near the maleic anhydride-grafted elastomer or the rubber phase in high-impact polystyrene, the elastic component deforms and absorbs some of the energy near the crack tip. When the filler is uniformly dispersed and has good interfacial bonding with the matrix resin, the load-bearing and crack-deflecting effects of the needle-like wollastonite can be simultaneously utilized with the energy dissipation effect of the elastic component's deformation, reducing the risk of material embrittlement caused by simply adding inorganic fillers.

[0039] During fused deposition modeling (FDM), after the extruded melt channel comes into contact with the previous melt channel, polystyrene segments diffuse and entangle on both sides of the interface, forming interlayer bonds upon cooling. Filler agglomeration, insufficient filler surface wetting, or uneven elastomer distribution can occupy part of the melt channel contact area and may create localized stress concentration points. After secondary melt blending, the wear-resistant and toughening masterbatch exhibits improved uniformity of distribution of wear-resistant fillers and toughening components in the polystyrene matrix resin, reducing local viscosity differences and fluctuations in localized solid concentration in the melt, resulting in more stable melt channel spreading and interlayer contact.

[0040] During filament extrusion, filler agglomerates and local composition fluctuations can cause fluctuations in die pressure and melt flow rate, further leading to changes in filament diameter. After pretreatment, premixing, masterbatch melt composite, and secondary melt blending, the distribution of needle-like wollastonite and polytetrafluoroethylene micropowder in the melt is more uniform, local high-viscosity areas and particle agglomerates are reduced, and the stability of die pressure and extrusion flow rate is correspondingly improved. Therefore, the filament diameter fluctuation of the filaments obtained in the examples is lower than that of the comparative examples without the preparation of wear-resistant and toughening functional masterbatch or without filler pretreatment.

[0041] When the printed part is under frictional conditions, needle-like wollastonite can bear part of the normal load on the worn surface and improve the resistance of the polystyrene matrix resin to frictional ploughing. Under frictional shearing, polytetrafluoroethylene (PTFE) micropowder can gradually enter the contact interface and form fluoropolymer transfer products on the worn surfaces of the workpiece and sample, reducing local frictional shear resistance. If the needle-like wollastonite is unevenly dispersed or its interfacial bonding with the matrix resin is insufficient, frictional loads can easily cause filler pull-out, particle shedding, and pit formation; localized agglomeration of PTFE micropowder also makes it difficult to form a uniform and stable lubricating effect.

[0042] In this invention, silane coupling agent treatment improves the interfacial wetting between acicular wollastonite and the organic polymer; masterbatch melt blending improves the pre-dispersion state of acicular wollastonite, polytetrafluoroethylene (PTFE) micropowder, and toughening components; and secondary melt blending further dilutes and disperses the masterbatch in the polystyrene matrix resin. The load-bearing and anti-ploughing effects of acicular wollastonite, the solid lubrication effect of PTFE micropowder, the deformation energy dissipation effect of maleic anhydride-grafted elastomer and high-impact polystyrene, and the interfacial modulation effect of styrene-maleic anhydride copolymer collectively affect the interlayer bonding performance, impact resistance, and wear resistance of the printed parts.

[0043] Compared with existing technologies, this invention does not employ a process of directly blending polystyrene matrix resin, elastomer toughening components, acicular wollastonite, and polytetrafluoroethylene (PTFE) micropowder in a single step. Instead, it sequentially performs silane coupling agent treatment on acicular wollastonite, premixing the treated acicular wollastonite with PTFE micropowder, melt-compositing and granulation of the wear-resistant and toughening functional masterbatch, and secondary melt-blending of the masterbatch with the polystyrene matrix resin. This process sequence improves the dispersion uniformity of the wear-resistant filler and the interfacial bonding between the filler and the polystyrene matrix resin, reducing filler agglomeration and local compositional fluctuations. The resulting polystyrene composite filament exhibits smaller filament diameter fluctuations, and the printed parts possess higher Z-axis tensile strength, shallow-notched simply supported beam impact strength, and lower frictional mass loss.

[0044] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention pre-melt-composite of needle-shaped wollastonite and polytetrafluoroethylene (PTFE) micropowder, pretreated with silane coupling agent, with maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer and styrene-maleic anhydride copolymer to form a wear-resistant and toughening functional masterbatch. This allows the hard wear-resistant filler, solid lubricant filler, and elastomer toughening phase to form a confined and correlated structure before entering the polystyrene matrix. Compared with the method of directly blending the components in one step, this invention can reduce the direct exposure of needle-shaped wollastonite and PTFE micropowder on the surface of the filament and at the interface of the printing melt channel, reducing the possibility of hard filler blocking the diffusion of polystyrene chain segments between layers. The maleic anhydride-grafted elastomer coating or embedding around the wear-resistant filler can suppress the local soft phase enrichment of the elastomer during the cooling process and buffer the stress concentration around the filler when the printed part is subjected to impact or interlayer load. The styrene-maleic anhydride copolymer forms an interfacial transition between the polystyrene matrix, elastomer, and pretreated filler, which is beneficial for maintaining the stable dispersion of the wear-resistant and toughened composite dispersion unit in the continuous matrix. Detailed Implementation

[0045] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0046] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0047] General-purpose polystyrene was produced using RG-525B from Huizhou Renxin New Materials Co., Ltd., with a melt flow rate of 8.0 g / 10 min at 200℃ and 5 kg. High-impact polystyrene was produced using RH-825 from Huizhou Renxin New Materials Co., Ltd., with a melt flow rate of 4.5 g / 10 min at 200℃ and 5 kg. Maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer was produced using Coace. W1G-4 has a melt flow rate of 3–9 g / 10 min at 190℃ and 2.16 kg; the acicular wollastonite has an aspect ratio of 15 and a particle size of 800 mesh; the polytetrafluoroethylene micro powder is TPD-505SA or TPD-508SA from Fuzhou Taipuda New Materials Co., Ltd., where the D50 particle size of TPD-505SA is 3.0–5.0 μm and the D50 particle size of TPD-508SA is 5.1–8.0 μm; the styrene-maleic anhydride copolymer is SMA1000, with an acid value of 480 mg KOH / g, a number-average molecular weight of 2000, and a weight-average molecular weight of 5500.

[0048] Example 1

[0049] This embodiment provides a method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing, comprising the following steps:

[0050] S1, γ-aminopropyltriethoxysilane was added to a mixed solution of ethanol and water and stirred for 20 min to obtain a silane treatment solution; the mass ratio of ethanol, water and γ-aminopropyltriethoxysilane was 100:3:1; needle-shaped wollastonite was added to a high-speed mixer, the silane treatment solution was sprayed on, and mixing was continued for 10 min, followed by drying at 90°C for 2 h; polytetrafluoroethylene micro powder was added to the dried needle-shaped wollastonite and premixed for 5 min to obtain a pretreated wear-resistant filler; the mass ratio of needle-shaped wollastonite, polytetrafluoroethylene micro powder and γ-aminopropyltriethoxysilane was 100:16.7:0.8;

[0051] S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer, and the pretreated wear-resistant filler are melt-composite and granulated to obtain wear-resistant and toughening functional masterbatch; in the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, needle-shaped wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and γ-aminopropyltriethoxysilane is 100:60:10:6:0.5; the melt-composite granulation is carried out using a twin-screw extruder, the melt-composite temperature is 170℃, and the screw speed is 120rpm;

[0052] S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch, and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules; wherein, the mass ratio of general-purpose polystyrene to high-impact polystyrene is 1:0.3, the mass ratio of polystyrene matrix resin, wear-resistant and toughening functional masterbatch, and processing aids is 100:18:0.6, and the processing aids are composed of antioxidant 1010 and ethylene bis-stearamide in a mass ratio of 1:2; during secondary melt blending, general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding, and the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding; the secondary melt blending temperature is 175℃, and the screw speed is 120rpm;

[0053] S4, the composite material granules are extruded into filaments using a single screw extruder at an extrusion temperature of 185°C and a traction speed of 2.5 m / min. The extruded filaments are cooled, measured, and wound to obtain polystyrene composite material filaments with a diameter of 1.75 mm.

[0054] Example 2

[0055] This embodiment provides a method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing, comprising the following steps:

[0056] S1, γ-glycidoxypropyltrimethoxysilane was added to a mixed solution of ethanol and water and stirred for 25 min to obtain a silane treatment solution; the mass ratio of ethanol, water and γ-glycidoxypropyltrimethoxysilane was 100:6:3; needle-shaped wollastonite was added to a high-speed mixer, the silane treatment solution was sprayed on, and mixing was continued for 12 min, followed by drying at 95°C for 2.5 h; polytetrafluoroethylene micro powder was added to the dried needle-shaped wollastonite and premixed for 6 min to obtain a pretreated wear-resistant filler; the mass ratio of needle-shaped wollastonite, polytetrafluoroethylene micro powder and γ-glycidoxypropyltrimethoxysilane was 100:25.9:1.4;

[0057] S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer, and the pretreated wear-resistant filler are melt-composite and granulated to obtain wear-resistant and toughening functional masterbatch; in the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, needle-like wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and γ-glycidyl etheroxypropyltrimethoxysilane is 100:85:22:12:1.2; the melt-composite granulation is carried out using a twin-screw extruder, the melt-composite temperature is 185℃, and the screw speed is 160rpm;

[0058] S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch, and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules; wherein, the mass ratio of general-purpose polystyrene to high-impact polystyrene is 1:0.5, the mass ratio of polystyrene matrix resin, wear-resistant and toughening functional masterbatch, and processing aids is 100:30:1.1, and the processing aids are composed of antioxidant 1010, antioxidant 168, and zinc stearate in a mass ratio of 1:1:3.5; during secondary melt blending, general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding, and the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding; the secondary melt blending temperature is 190℃, and the screw speed is 150rpm;

[0059] S4, the composite material granules are extruded into filaments using a single screw extruder at an extrusion temperature of 200°C and a traction speed of 4 m / min. The extruded filaments are cooled, measured, and wound to obtain polystyrene composite material filaments with a diameter of 1.75 mm.

[0060] Example 3

[0061] This embodiment provides a method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing, comprising the following steps:

[0062] S1, γ-methacryloxypropyltrimethoxysilane was added to a mixed solution of ethanol and water and stirred for 30 min to obtain a silane treatment solution; the mass ratio of ethanol, water and γ-methacryloxypropyltrimethoxysilane was 100:10:6; needle-shaped wollastonite was added to a high-speed mixer, the silane treatment solution was sprayed on, and mixing was continued for 15 min, followed by drying at 100℃ for 3 h; polytetrafluoroethylene micro powder was added to the dried needle-shaped wollastonite and premixed for 8 min to obtain a pretreated wear-resistant filler; the mass ratio of needle-shaped wollastonite, polytetrafluoroethylene micro powder and γ-methacryloxypropyltrimethoxysilane was 100:31.8:2.7;

[0063] S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer, and the pretreated wear-resistant filler are melt-composite and granulated to obtain wear-resistant and toughening functional masterbatch; in the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, needle-shaped wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and γ-methacryloyloxypropyltrimethoxysilane is 100:110:35:20:3.0; the melt-composite granulation is carried out using an internal mixer, the melt-composite temperature is 200℃, and the rotor speed is 100rpm.

[0064] S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch, and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules; wherein, the mass ratio of general-purpose polystyrene to high-impact polystyrene is 1:0.75, the mass ratio of polystyrene matrix resin, wear-resistant and toughening functional masterbatch, and processing aids is 100:42:1.7, and the processing aids are composed of antioxidant 168, ethylene bis-stearamide, and polyethylene wax in a mass ratio of 1:2:2; during secondary melt blending, general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding, and the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding; the secondary melt blending temperature is 205℃, and the screw speed is 135rpm;

[0065] S4, the composite material granules are extruded into filaments using a single screw extruder at an extrusion temperature of 215°C and a traction speed of 6 m / min. The extruded filaments are cooled, measured, and wound to obtain polystyrene composite material filaments with a diameter of 1.75 mm.

[0066] Example 4

[0067] This embodiment provides a method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing, comprising the following steps:

[0068] S1, γ-glycidoxypropyltrimethoxysilane was added to a mixed solution of ethanol and water and stirred for 35 min to obtain a silane treatment solution; the mass ratio of ethanol, water and γ-glycidoxypropyltrimethoxysilane was 100:15:10; needle-shaped wollastonite was added to a high-speed mixer, the silane treatment solution was sprayed on, and mixing was continued for 18 min, followed by drying at 105℃ for 3.5 h; polytetrafluoroethylene micro powder was added to the dried needle-shaped wollastonite and premixed for 10 min to obtain a pretreated wear-resistant filler; the mass ratio of needle-shaped wollastonite, polytetrafluoroethylene micro powder and γ-glycidoxypropyltrimethoxysilane was 100:30.7:3.1;

[0069] S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer, and the pretreated wear-resistant filler are melt-composite and granulated to obtain wear-resistant and toughening functional masterbatch; in the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, needle-shaped wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and γ-glycidyl etheroxypropyltrimethoxysilane is 100:140:43:29:4.3; the melt-composite granulation is carried out using an internal mixer, the melt-composite temperature is 210℃, and the rotor speed is 80 rpm;

[0070] S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch, and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules; wherein, the mass ratio of general-purpose polystyrene to high-impact polystyrene is 1:1.0, the mass ratio of polystyrene matrix resin, wear-resistant and toughening functional masterbatch, and processing aids is 100:55:2.3, and the processing aids are composed of antioxidant 1010, antioxidant 168, zinc stearate, and polyethylene wax in a mass ratio of 1:1:2:2; during secondary melt blending, general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding, and the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding; the secondary melt blending temperature is 220℃, and the screw speed is 100rpm;

[0071] S4, the composite material granules are extruded into filaments using a twin-screw extrusion filament forming equipment at an extrusion temperature of 230℃ and a traction speed of 8m / min. The extruded filaments are cooled, measured, and wound to obtain polystyrene composite material filaments with a diameter of 2.85mm.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing. The difference between this method and Example 2 is that, instead of preparing a wear-resistant and toughening functional masterbatch, general-purpose polystyrene, high-impact polystyrene, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, silane coupling agent-treated needle-shaped wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and processing aids are directly added to a twin-screw extruder and melt-blended and granulated once at 190°C and 150 rpm. Subsequently, the mixture is extruded into filaments according to S4 in Example 2. Other process parameters and operating conditions are exactly the same as in Example 2.

[0074] Comparative Example 2

[0075] This comparative example provides a method for preparing a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing. The difference between this method and Example 2 is that maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer is not added to the wear-resistant and toughening functional masterbatch. The styrene-maleic anhydride copolymer, silane coupling agent-treated needle-shaped wollastonite, and polytetrafluoroethylene micro powder are dry-mixed to obtain a comparative filler mixture. During the secondary melt blending, general-purpose polystyrene, high-impact polystyrene, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, and processing aids are added to the twin-screw extruder through the main feed port, and the comparative filler mixture is added to the twin-screw extruder through the side feed port. Other process parameters and operating conditions are exactly the same as in Example 2.

[0076] Comparative Example 3

[0077] This comparative example provides a method for preparing a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing. The difference between this method and Example 2 is that the needle-shaped wollastonite and polytetrafluoroethylene micro powder are not pretreated with silane coupling agents, but are directly melt-composite and granulated with maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer and styrene-maleic anhydride copolymer to prepare wear-resistant and toughening functional masterbatch. Other process parameters and operating conditions are exactly the same as in Example 2.

[0078] Comparative Example 4

[0079] This comparative example provides a method for preparing a high-toughness and wear-resistant polystyrene composite material for non-metallic additive manufacturing. The difference between this method and Example 2 is that the styrene-maleic anhydride copolymer is not added, and the same mass of polystyrene matrix resin is used to replace the styrene-maleic anhydride copolymer. The mass ratio of general-purpose polystyrene to high-impact polystyrene in the polystyrene matrix resin used for replacement is 1:0.5. Other process parameters and operating conditions are exactly the same as in Example 2.

[0080] Performance testing:

[0081] The polystyrene composite filaments obtained in Examples 1-4 and Comparative Examples 1-4 were dried at 60°C for 4 hours before performance testing. Before testing, all samples were placed in an environment of 23°C and 50% relative humidity for 24 hours, and then the tests were conducted under the same conditions. The test results are shown in Table 1.

[0082] Wire diameter fluctuation test: Three 2m samples were taken from each group of wires and measured using a digital outside micrometer with an accuracy of 0.001mm. Measurements were taken every 100mm along the length of each wire, for a total of 20 measurements. Measurements were taken once in each of two mutually perpendicular directions at each location, and the average value was taken as the wire diameter at that location. The wire diameter fluctuation for each wire was calculated as the difference between the maximum and minimum wire diameter values. The average value of the wire diameter fluctuations for each group of three wires was taken, in mm.

[0083] Z-direction tensile strength test: The filaments prepared in the examples and comparative examples were used for fused deposition modeling (FDM) to print Z-direction tensile specimens. The specimens were dumbbell-shaped, with a total length of 75 mm, a clamping end width of 10 mm, a narrow parallel section length of 30 mm, a narrow parallel section width of 5 mm, and a thickness of 4 mm. During printing, the nozzle diameter was 0.4 mm, the nozzle temperature was 220 °C, the heated bed temperature was 90 °C, the layer thickness was 0.2 mm, the printing speed was 40 mm / s, the infill rate was 100%, and the printing path direction was kept consistent. During specimen printing, the layer stacking direction was aligned with the tensile stress direction to evaluate the Z-direction interlayer bonding performance of the printed parts. Five specimens were prepared for each group. Before testing, the specimens were placed in an environment of 23 °C and 50% relative humidity for 24 hours. Tensile testing was performed using a universal testing machine with a clamp spacing of 50 mm and a tensile speed of 5 mm / min. The maximum load at specimen fracture was recorded, and the Z-direction tensile strength was calculated based on the cross-sectional area of ​​the narrow parallel section of the specimen, in MPa. The average value of the five specimens in each group was taken.

[0084] Shallow-notch simply supported beam impact strength test: The filaments prepared in the examples and comparative examples were printed into long strip-shaped impact specimens, with printing conditions consistent with the Z-direction tensile strength test. The specimen size was 80mm × 10mm × 4mm, with a V-shaped notch machined in the middle of the specimen. The notch depth was 1.0mm, the bottom radius of the notch was 0.25mm, and the remaining thickness at the notch was 3.0mm. Five specimens were prepared for each group. Before testing, the specimens were placed in an environment of 23℃ and 50% relative humidity for 24 hours. The simply supported beam impact test was conducted using a pendulum impact testing machine according to GB / T 1043.1, with a pendulum impact energy of 1J and a pendulum impact velocity of 2.9m / s. During the test, the energy absorbed by the specimen at fracture was recorded. Only specimens that achieved effective fracture and whose absorbed energy was within 10%-80% of the nominal energy of the pendulum were counted. If the specimen did not achieve effective fracture or the absorbed energy exceeded the above range, the pendulum energy was changed and the test was repeated. The impact strength of a shallow-notched simply supported beam is calculated by dividing the energy absorbed at fracture by the remaining cross-sectional area at the notch, and the unit is kJ / m². 2 The average value of 5 valid samples in each group is taken.

[0085] Frictional mass loss test: The filaments prepared in the examples and comparative examples were printed into block-shaped wear specimens with dimensions of 40mm × 20mm × 4mm. The printing conditions were the same as those for the Z-direction tensile strength test, and three specimens were prepared for each group. Before testing, the specimens were dried at 60℃ for 4 hours, and then placed in an environment of 23℃ and 50% relative humidity for 24 hours. The mass of the specimen before wear was weighed using an analytical balance with an accuracy of 0.1mg. A reciprocating friction and wear testing machine was used for wear treatment. The abrasive was a 6mm diameter stainless steel ball, the normal load was 10N, the reciprocating stroke was 10mm, the reciprocating frequency was 2Hz, and the wear time was 30min. After wear, the wear area was gently brushed 10 times in the same direction with a soft brush, and then the specimen surface was gently blown with a rubber bulb. The mass of the specimen after wear was then weighed. The frictional mass loss was calculated as the difference between the mass of the specimen before wear and the mass of the specimen after wear, in mg. The average value of the three specimens in each group was taken.

[0086] Table 1. Test results of polystyrene composite materials in Examples 1-4 and Comparative Examples 1-4

[0087]

[0088] As shown in Table 1, compared with Example 2, the wire diameter fluctuation of Comparative Examples 1 to 4 all increased, the Z-direction tensile strength and the shallow notch simply supported beam impact strength all decreased, and the frictional mass loss all increased.

[0089] Comparative Example 1 did not prepare a wear-resistant and toughening functional masterbatch; all components were directly melt-blended in a single step. Compared to Example 2, the wear-resistant filler and toughening components lacked a pre-melt composite process, resulting in reduced dispersion uniformity of needle-like wollastonite and polytetrafluoroethylene micropowder in the polystyrene matrix resin, and consequently increased filament diameter fluctuations and frictional mass loss of the printed parts.

[0090] In Comparative Example 2, the maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer was not pre-melted and compounded with acicular wollastonite and polytetrafluoroethylene micropowder, but was directly added to the polystyrene matrix resin during secondary melt blending. The pre-dispersion effect between the wear-resistant filler and the elastomer toughening component was weakened, and the Z-direction tensile strength, shallow notched simply supported beam impact strength, and wear resistance of the printed part were all lower than those in Example 2.

[0091] In Comparative Example 3, the acicular wollastonite was not treated with a silane coupling agent, which reduced the interfacial wetting and compatibility between the acicular wollastonite and the organic polymer. This made it easier for uneven local dispersion to occur during the melt blending process, resulting in increased fluctuations in the filament diameter and a decrease in the mechanical properties and wear resistance of the printed parts.

[0092] Comparative Example 4 did not include styrene-maleic anhydride copolymer. After treatment, the interfacial compatibility between the needle-like wollastonite and the polystyrene matrix resin decreased, and the dispersion stability of the wear-resistant filler in the matrix resin decreased. As a result, the Z-direction tensile strength, shallow notched simply supported beam impact strength, and wear resistance of the printed parts were lower than those of Example 2.

[0093] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing, characterized in that, The composite material is used for fused deposition modeling, and the composite material includes a polystyrene matrix resin, a wear-resistant and toughening functional masterbatch, and processing aids; The mass ratio of the polystyrene matrix resin, the wear-resistant and toughening functional masterbatch, and the processing aid is 100:(18-55):(0.6-2.3). The polystyrene matrix resin includes general-purpose polystyrene and high-impact polystyrene; The wear-resistant and toughening functional masterbatch is a particle formed by pre-melting and compounding maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer, and needle-shaped wollastonite pretreated with silane coupling agent.

2. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The mass ratio of general-purpose polystyrene to high-impact polystyrene is 1:(0.3-1.0).

3. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The melt flow rate of the general-purpose polystyrene under GB / T 3682, 200℃, and 5kg conditions is 6-10g / 10min, and the melt flow rate of the high-impact polystyrene under GB / T 3682, 200℃, and 5kg conditions is 3.5-5.5g / 10min.

4. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, In the wear-resistant and toughening functional masterbatch, the mass ratio of maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, needle-shaped wollastonite, polytetrafluoroethylene micro powder, styrene-maleic anhydride copolymer and silane coupling agent is 100:(60-140):(10-43):(6-29):(0.5-4.3).

5. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The acicular wollastonite has an aspect ratio of 7-25 and a particle size of 600-1250 mesh; the polytetrafluoroethylene micro powder has a D50 particle size of 3.0-8.0 μm.

6. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The mass ratio of the needle-shaped wollastonite to the polytetrafluoroethylene micro powder is 1:(0.1-0.5).

7. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer has a melt flow rate of 3–9 g / 10 min at 190 °C and 2.16 kg.

8. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The styrene-maleic anhydride copolymer has an acid value of 470-500 mg KOH / g, a number-average molecular weight of 1800-2200, and a weight-average molecular weight of 5000-6000.

9. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The processing aids include antioxidants and lubricants; the antioxidants include antioxidant 1010 and / or antioxidant 168; the lubricants include one or more of ethylene bis-stearamide, zinc stearate, and polyethylene wax.

10. The high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing according to claim 1, characterized in that, The composite material is a filament for fused deposition modeling, and the diameter of the filament is 1.75±0.05mm or 2.85±0.05mm.

11. A method for preparing a high-toughness, wear-resistant polystyrene composite material for non-metallic additive manufacturing as described in any one of claims 1-10, characterized in that, The steps include the following: S1, add silane coupling agent to a mixed solution of ethanol and water to obtain silane treatment solution; mix the silane treatment solution with needle-shaped wollastonite, dry it, and then add polytetrafluoroethylene micro powder for premixing to obtain pretreated wear-resistant filler. S2, maleic anhydride-grafted styrene-ethylene / butene-styrene copolymer, styrene-maleic anhydride copolymer and the pretreated wear-resistant filler are melt-composite granulated to obtain wear-resistant and toughening functional masterbatch; S3, general-purpose polystyrene, high-impact polystyrene, the wear-resistant and toughening functional masterbatch and processing aids are subjected to secondary melt blending and granulation to obtain composite material granules; S4, the composite material granules are extruded into filaments to obtain polystyrene composite material filaments for melt deposition molding.

12. The preparation method according to claim 11, characterized in that, In S1, the silane coupling agent is γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane, and the mass ratio of ethanol, water and silane coupling agent is 100:(3-15):(1-10).

13. The preparation method according to claim 11, characterized in that, In S2, the melt compounding granulation is carried out using a mixer or a twin-screw extruder, with a melt compounding temperature of 170-210℃ and a screw speed or rotor speed of 60-250 rpm.

14. The preparation method according to claim 11, characterized in that, In S3, the wear-resistant and toughening functional masterbatch is added to the twin-screw extruder via side feeding, and the general-purpose polystyrene, high-impact polystyrene, and processing aids are added to the twin-screw extruder via main feeding; the secondary melt blending temperature is 175-220℃, and the screw speed is 100-250rpm.

15. The preparation method according to claim 11, characterized in that, In S4, extrusion into filaments is carried out using a single-screw extruder or a twin-screw extrusion filament equipment. The extrusion temperature is 180-230℃, and the traction speed is 2-10m / min. The extruded filaments are then cooled, measured in diameter, and wound up.

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