Laser-sintered polyphenylene sulfide composite material and preparation method thereof

Abstract

The invention relates to a polyphenylene sulfide composite material suitable for laser sintering and a preparation method of the polyphenylene sulfide composite material. The polyphenylene sulfide composite material can be used for preparing parts, such as automobiles, electronic and electrical products, robots and the like, which have the requirements of complex structures, high temperature resistance, high flame retardancy, dimensional stability and chemical resistance through laser sintering, printing and molding. The polyphenylene sulfide composite material is prepared from polyphenylene sulfide powder, ground glass fibers, potassium titanate whiskers, hexagonal boron nitride, graphene ethanol slurry, a powdery silane coupling agent, hydrophobic modified fumed silica and an antioxidant. The polyphenylene sulfide composite material prepared by the invention has excellent powder flowability, good powder leveling property during powder laying and excellent melting effect during laser sintering molding, and a prepared sample has the characteristics of fine surface, few internal defects, low warping and excellent anisotropic mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a laser-sintered polyphenylene sulfide composite material and its preparation method. This polyphenylene sulfide composite material can be used to prepare automotive, electronic and electrical, robotic and other components with fine surface, few internal defects, low warpage, and excellent anisotropic mechanical properties through laser sintering. Background Technology

[0002] 3D printing is a rapid prototyping technology. Compared to traditional injection molding, 3D printing can quickly manufacture complex three-dimensional solid parts without molds, significantly shortening product development cycles and reducing development costs. 3D printing technologies include fused particulate printing, filament fusion printing, UV curing printing, and powder laser sintering printing.

[0003] Powder laser sintering technology uses a high-energy laser beam to selectively sinter powdered materials, forming complex structural components through layer stacking. This technology features no need for support structures, high material utilization, and compatibility with high-performance materials, and is widely used in industrial parts customization, aerospace, automotive, medical and other fields.

[0004] Polyphenylene sulfide (PPS) resin is the world's sixth largest engineering plastic. Its unique molecular structure endows it with excellent heat resistance, chemical corrosion resistance, and flame retardancy, making it a core material in the automotive, electrical, and robotics industries. However, pure PPS powder used in laser sintering produces parts with low mechanical strength. While simple fiber reinforcement of PPS powder can improve mechanical properties, the orientation of the fibers and the large gaps between the fibers and the powder after fusion result in significant internal defects in the parts, which can easily become failure points during long-term use.

[0005] Patent CN108165011A uses polyphenylene sulfide powder, ground glass fiber, glass sheet, coupling agent, and powder flow aid to prepare a modified polyphenylene sulfide composite material that can be used for laser sintering. However, the glass sheet used is relatively large. Although it can improve printing warpage, it forms a bridging structure with the glass fiber inside the powder, which hinders the bonding of the polyphenylene sulfide powder after melting, resulting in large gap defects inside.

[0006] Patent CN109689788A uses polyphenylene sulfide powder and fluoropolymer powder to prepare polyphenylene sulfide composite materials that can be laser sintered. However, because the fluoropolymer powder cannot melt at the sintering temperature of the polyphenylene sulfide powder, it becomes a defect point, resulting in poor overall mechanical properties of the printed parts.

[0007] Therefore, it is necessary to develop a laser-sintered polyphenylene sulfide composite material that can produce parts with a smooth surface, low warpage, excellent anisotropic mechanical properties, and few internal defects, in order to overcome the technical shortcomings of existing materials. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a laser-sintered polyphenylene sulfide (PPS) composite material and its preparation method. This PPS composite material comprises PPS powder, ground glass fiber, potassium titanate whiskers, hexagonal boron nitride, graphene ethanol slurry, powdered silane coupling agent, hydrophobically modified fumed silica, and an antioxidant. By optimizing the powder composition, this invention produces a PPS composite material with excellent powder flowability, good powder leveling during spreading, and excellent melting effect during laser sintering. The resulting sample exhibits a fine surface, few internal defects, low warpage, and excellent anisotropic mechanical properties.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A polyphenylene sulfide composite material suitable for laser sintering, comprising the following raw materials:

[0011] Polyphenylene sulfide powder 60-90%

[0012] Grinded glass fiber 2~25%

[0013] Potassium titanate whiskers 2-5%

[0014] 5-10% hexagonal boron nitride

[0015] Graphene ethanol slurry (effective solids content) 0.2~1%

[0016] Powdered silane coupling agent 0.2%~0.5%

[0017] Hydrophobically modified fumed silica 0.2~1%

[0018] Antioxidant 0.4~1%.

[0019] In this invention, the polyphenylene sulfide powder is a linear polyphenylene sulfide resin with a melting point of 275~285℃ and a melt index of 150~300g / 10min (316℃, 5kg).

[0020] In this invention, the polyphenylene sulfide powder is a mixture of two polyphenylene sulfide powders with different particle size distributions. One large-particle-size polyphenylene sulfide powder has a D50 particle size of 50-70 μm and accounts for 70-90% of its mass. The other small-particle-size polyphenylene sulfide powder has a D50 particle size of 15-30 μm and accounts for 10-30% of its mass.

[0021] In this invention, the average diameter of the polished glass fiber is 5~15μm and the average length is 100~200μm.

[0022] In this invention, the potassium titanate whiskers have an average diameter of 0.1~0.6μm and an average length of 5~20μm.

[0023] In this invention, the D50 particle size of the hexagonal boron nitride is 2~5μm.

[0024] In this invention, the graphene ethanol slurry contains 1-5% graphene by mass, has a thickness of 0.5-5 nm, and a diameter of 0.5-3 μm.

[0025] In this invention, the powdered silane coupling agent is a hydrolyzed aminosiloxane oligomer with a D50 particle size of 10-30 μm and an amino equivalent of 300-500 (KOH mg / g).

[0026] In this invention, the D50 particle size of the hydrophobically modified fumed silica is 5~30nm.

[0027] In this invention, the antioxidant is a compound of three types: hindered phenolic antioxidant, phosphite antioxidant, and benzofuranone antioxidant. The hindered phenolic antioxidant accounts for 20-30% of the total antioxidant, the phosphite antioxidant accounts for 20-30% of the total antioxidant, and the benzofuranone antioxidant accounts for 40-50% of the total antioxidant.

[0028] The present invention also provides a method for preparing the polyphenylene sulfide composite material, comprising the following steps:

[0029] (1) Add polyphenylene sulfide powder to a high-speed mixer with spray and heating functions, and spray graphene ethanol slurry while stirring. Set the speed to 1000~1500 rpm / min. After stirring for 15~30 min, heat the high-speed mixer to 100~120℃ and continue stirring for 30~60 min to remove residual ethanol.

[0030] (2) Add hydrophobically modified fumed silica, antioxidant, powdered silane coupling agent and hexagonal boron nitride to the above high-speed mixer and continue stirring for 15-30 minutes, setting the speed to 1000-1500 rpm / min.

[0031] (3) Add the ground glass fiber and potassium titanate whiskers to the high-speed mixer and continue stirring for 30-60 minutes, setting the speed to 200-500 rpm.

[0032] (4) The polyphenylene sulfide powder obtained by the above mixing is sieved through a 100-150 mesh vibrating screen to obtain the final polyphenylene sulfide composite material.

[0033] The polyphenylene sulfide composite material suitable for laser sintering described in this invention can be used to prepare automotive, electronic, electrical, and robotic components with a smooth surface, few internal defects, low warpage, and excellent mechanical properties.

[0034] The technical solution of this invention has the following advantages over existing technical solutions:

[0035] 1. This invention uses PPS powder with a suitable melt index to ensure good melt flowability and mechanical properties during laser sintering, while avoiding the use of PPS powder with an excessively high melt index, as the low molecular weight PPS resulting from an excessively high melt index will lead to lower strength and toughness of the printed parts.

[0036] 2. This invention uses a blend of large-particle-size and small-particle-size PPS powders. Large-particle-size PPS powder has better leveling properties than small-particle-size PPS powder, but its larger interparticle gaps make it prone to void defects during melting. The blended small-particle-size PPS powder fills these gaps, resulting in a denser powder after laser sintering. Simultaneously, the proportion of small-particle-size PPS powder is controlled to avoid excessive content leading to poor powder leveling, which could prevent the powder spreading roller from evenly distributing the powder on the printed part during printing, thus introducing new internal defects.

[0037] 3. This invention uses graphene-ethanol slurry as a laser absorber. If graphene powder and PPS powder are directly physically dispersed, the small particle size and large specific surface area of ​​graphene make it prone to agglomeration, hindering effective dispersion within the PPS powder. However, preparing graphene as a low-concentration ethanol slurry allows for better dispersion of graphene due to ethanol's excellent wettability. Ethanol also exhibits excellent wetting properties for PPS powder, enabling better dispersion of graphene onto the PPS powder surface during mixing. Graphene possesses excellent laser absorption capabilities, effectively converting light energy into heat energy. Furthermore, its excellent thermal conductivity allows it to transfer its own heat energy to the PPS powder, resulting in better melting and bonding of the PPS powder.

[0038] 4. This invention uses potassium titanate whiskers as a synergistic reinforcing agent for polished glass fibers. Its small diameter allows it to fill the gaps between the polished glass fibers and PPS powder, improving the internal density of the printed material and enhancing its overall mechanical properties.

[0039] 5. This invention uses hexagonal boron nitride as a size-stabilizing filler and a thermally conductive filler. Since hexagonal boron nitride has a layered structure, it can improve the warping caused by glass fiber orientation. Hexagonal boron nitride has excellent thermal conductivity, which can better transfer heat energy to PPS powder and promote the melting and bonding of PPS powder.

[0040] 6. This invention uses powdered silane coupling agent as an interfacial binder for grinding glass fiber and PPS powder, which has a good dispersion effect and can improve the overall mechanical properties of the printed parts.

[0041] 7. This invention uses a combination of hindered phenolic antioxidants, phosphite antioxidants, and lactone-type (benzofuranone) antioxidants as the antioxidant system, which solves the problems of yellowing edges and clumping during powder printing and improves the secondary utilization efficiency of powder printing. Detailed Implementation

[0042] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments. Unless otherwise specified, the raw materials used in the embodiments or comparative examples are commercially available raw materials.

[0043] The apparatus and main raw material sources used in the embodiments and comparative examples of this invention are as follows:

[0044] High-speed heating mixer: MIXACOLABHM10

[0045] Laser sintering printer: Farsoon Technologies HT403P

[0046] Polyphenylene sulfide powder: PPSMP50, D50 particle size 50μm, melting point 280℃, melt index 250g / 10min, Wanhua Chemical

[0047] Polyphenylene sulfide powder: PPSMP20, D50 particle size 20μm, melting point 280℃, melt index 250g / 10min, Wanhua Chemical

[0048] Polyphenylene sulfide powder: PPSHP50, D50 particle size 50μm, melting point 280℃, melt index 500g / 10min, Wanhua Chemical

[0049] Polyphenylene sulfide powder: PPSHP20, D50 particle size 20μm, melting point 280℃, melt index 500g / 10min, Wanhua Chemical

[0050] Polished glass fiber: MEF-10-100, diameter 10μm, average length 150μm, Yata Technology Co., Ltd.

[0051] Potassium titanate whiskers: TISMOD, average diameter 0.3~0.6μm, average length 10~20μm, Otsuka Chemicals.

[0052] Hexagonal boron nitride: PCTF5, D50 particle size 5μm, Saint-Gobain, France

[0053] Graphene-ethanol slurry: TimesGraph, graphene content 2%, graphene thickness 1-3 nm, diameter 1-2 μm, Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences

[0054] Powdered silane coupling agent: X-88-491A, D50 particle size 15μm, amino equivalent 488KOH mg / g, Shin-Etsu Chemical.

[0055] Hydrophobically modified fumed silica: AEROSIL R812, D50 particle size 7nm, Evonik

[0056] Hindered phenolic antioxidants: 1010, a rising star in chemistry.

[0057] Phosphite antioxidants: S9228, Dover

[0058] Lactone-type (benzofuranone) antioxidants: Revonox 501, Qitai Chemical

[0059] The performance characterization method of the polyphenylene sulfide composite material of the present invention is as follows:

[0060] Bending strength: ISO 178;

[0061] Tensile strength: ISO 527;

[0062] Elongation at break: ISO 527;

[0063] Print warpage test method:

[0064] Place a Farsoon HT403P printing plate (150*150*3mm) on a horizontal table. Place a 500g weight on one corner of the plate. Then measure the vertical distance from the endpoint of the plate diagonally opposite to that corner to the horizontal table. The greater the vertical distance, the more severe the material warping.

[0065] Internal defect testing methods:

[0066] A curved sample (80*10*4mm) was printed using Farsoon HT403P. After the curved sample was broken, the porosity of the cross-section was observed using an optical microscope.

[0067] Powder yellowing test method:

[0068] The yellowing is assessed by visual inspection, with an evaluation scale of 1 to 5 points. The higher the number, the more severe the yellowing.

[0069] Method for testing powder agglomeration after printing:

[0070] The changes in clumping are judged by visual inspection, and the evaluation criteria are on a five-level scale from 1 to 5. The higher the number, the more severe the clumping.

[0071] Examples and Comparative Examples

[0072] Examples 1-4 (i.e., S1-4) and Comparative Examples 1-7 (i.e., D1-7) were prepared according to the raw materials and amounts in Table 1.

[0073] The preparation method of polyphenylene sulfide composite material is as follows: (1) Add polyphenylene sulfide powder to a high-speed mixer with spray and heating functions, and spray graphene ethanol slurry while stirring. Set the speed to 1200 rpm / min. After stirring for 20 min, heat the high-speed mixer to 100℃ and continue stirring for 45 min to remove residual ethanol solution; (2) Add hydrophobically modified fumed silica, antioxidant, powdered silane coupling agent and hexagonal boron nitride to the above high-speed mixer and continue stirring for 30 min. Set the speed to 1200 rpm / min; (3) Add ground glass fiber and potassium titanate whiskers to the above high-speed mixer and continue stirring for 45 min. Set the speed to 300 rpm; (4) Screen the polyphenylene sulfide powder obtained by mixing above through a 120 mesh vibrating screen to obtain the final polyphenylene sulfide composite material.

[0074] Table 1. Raw material consumption and performance of printed parts in the examples and comparative examples.

[0075]

[0076] As can be seen from Table 1, the polyphenylene sulfide parts printed in Examples 1-4 have excellent comprehensive mechanical properties, with advantages such as low warpage and small cross-sectional pores. The powder exhibits low yellowing and does not clump after printing.

[0077] Comparative Example 1 used polyphenylene sulfide powder with an excessively high melt index, resulting in a low molecular weight and consequently low overall mechanical properties of the printed part. Comparative Example 2 used only large-particle-size polyphenylene sulfide powder, leading to larger cross-sectional pores in the printed part and reduced overall mechanical properties. Comparative Example 3 used only small-particle-size polyphenylene sulfide powder; the small particle size resulted in poor leveling, leading to larger pore sizes in the printed part and reduced overall mechanical properties. Comparative Example 4 did not use graphene as a laser absorber, resulting in poor powder melting during printing, larger pore sizes in the printed part, and reduced overall mechanical properties. Comparative Example 5 did not use potassium titanate whiskers, increasing the internal pore size of the part and reducing overall mechanical properties. Furthermore, it lacked a combined antioxidant solution, resulting in yellowing edges and clumping during powder printing. Comparative Example 6 did not use hexagonal boron nitride, resulting in poorer printing melt flow, deteriorated overall mechanical properties of the part, and increased warpage. It also lacked a three-component antioxidant solution, leading to yellowing edges and clumping during powder printing. Comparative Example 7 did not use powdered silane coupling agent, resulting in poor interfacial bonding between the resin and inorganic filler, deteriorating overall mechanical properties of the part. It also lacked a three-component antioxidant solution, resulting in yellowing edges and clumping during powder printing.

[0078] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the embodiments and apply the general principles described herein to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A polyphenylene sulfide composite material, characterized in that: The polyphenylene sulfide composite material comprises the following raw materials: Polyphenylene sulfide powder 60-90% Grinded glass fiber 2~25% Potassium titanate whiskers 2-5% 5-10% hexagonal boron nitride Graphene-ethanol slurry, with a solids content of 0.2-1%. Powdered silane coupling agent 0.2%~0.5% Hydrophobically modified fumed silica 0.2~1% Antioxidant 0.4~1%.

2. The polyphenylene sulfide composite material according to claim 1, characterized in that, The polyphenylene sulfide powder is a linear polyphenylene sulfide resin with a melting point of 275~285℃ and a melt index of 150~300g / 10min (316℃, 5kg). The polyphenylene sulfide powder is a mixture of two polyphenylene sulfide powders with different particle size distributions. The larger particle size polyphenylene sulfide powder has a D50 particle size of 50~70μm and accounts for 70~90% of the total mass. The smaller particle size polyphenylene sulfide powder has a D50 particle size of 15~30μm and accounts for 10~30% of the total mass.

3. The polyphenylene sulfide composite material according to claim 1, characterized in that, The average diameter of the polished glass fiber is 5~15μm, and the average length is 100~200μm.

4. The polyphenylene sulfide composite material according to claim 1, characterized in that, The potassium titanate whiskers have an average diameter of 0.1~0.6μm and an average length of 5~20μm.

5. The polyphenylene sulfide composite material according to claim 1, characterized in that, The D50 particle size of the hexagonal boron nitride is 2~5μm.

6. The polyphenylene sulfide composite material according to claim 1, characterized in that, The graphene ethanol slurry has a graphene mass fraction of 1-5%, a graphene thickness of 0.5-5 nm, and a graphene diameter of 0.5-3 μm.

7. The polyphenylene sulfide composite material according to claim 1, characterized in that, The powdered silane coupling agent is a hydrolyzed aminosiloxane oligomer with a D50 particle size of 10-30 μm and an amino equivalent of 300-500 (KOH mg / g).

8. The polyphenylene sulfide composite material according to claim 1, characterized in that, The D50 particle size of the hydrophobically modified fumed silica is 5~30nm.

9. The polyphenylene sulfide composite material according to claim 1, characterized in that, The antioxidant is a compound of three types: hindered phenolic antioxidants, phosphite antioxidants, and benzofuranone antioxidants. Hindered phenolic antioxidants account for 20-30% of the total antioxidants, phosphite antioxidants account for 20-30% of the total antioxidants, and benzofuranone antioxidants account for 40-50% of the total antioxidants.

10. A method for preparing the polyphenylene sulfide composite material according to any one of claims 1-9, wherein the preparation method comprises the following steps: (1) Add polyphenylene sulfide powder to a high-speed mixer with spray and heating functions, and spray graphene ethanol slurry while stirring. Set the speed to 1000~1500 rpm / min. After stirring for 15~30 min, heat the high-speed mixer to 100~120℃ and continue stirring for 30~60 min to remove residual ethanol. (2) Add hydrophobically modified fumed silica, antioxidant, powdered silane coupling agent and hexagonal boron nitride to the above high-speed mixer and continue stirring for 15-30 min, setting the speed to 1000-1500 rpm / min; (3) Add the ground glass fiber and potassium titanate whiskers to the high-speed mixer and continue stirring for 30-60 minutes, setting the speed to 200-500 rpm; (4) The polyphenylene sulfide powder obtained by the above mixing is sieved through a 100-150 mesh vibrating screen to obtain the final polyphenylene sulfide composite material.

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