阅读说明：本技术 一种用于选区激光烧结的高分子复合粉末及其制备方法 (High-molecular composite powder for selective laser sintering and preparation method thereof ) 是由 段玉丰 李春 于 2020-12-31 设计创作，主要内容包括：本发明关于增材制造用高分子粉末材料技术领域,尤其涉及一种选区激光烧结用聚苯乙烯/氧化锌复合粉末的制备方法。该粉末由连续相聚苯乙烯、分散相乙烯醋酸乙烯酯共聚物和分散的纳米氧化锌构成。其中纳米氧化锌能够提供制品杀菌防霉功能,并且提高复合粉末的导热率,从而提高复合粉末材料对激光的吸收效果,减少了制件连续层之间的间隙。乙烯醋酸乙烯酯共聚物在提供材料的韧性的同时,其分子结构中的酯基能够大大改善高分子相与氧化锌粒子的亲和性,从而提高二者相间界面结合力,并且增强SLS制件的层间结合强度。产品中纳米氧化锌分散良好、粒径可以方便地在几微米至几十微米之间调控、粉末流动性好、制品韧性好。(The invention relates to the technical field of polymer powder materials for additive manufacturing, in particular to a preparation method of polystyrene/zinc oxide composite powder for selective laser sintering. The powder consists of continuous phase polystyrene, dispersed phase ethylene-vinyl acetate copolymer and dispersed nano zinc oxide. The nano zinc oxide can provide the sterilization and mildew-proof functions of the product, and the heat conductivity of the composite powder is improved, so that the laser absorption effect of the composite powder material is improved, and gaps among continuous layers of the product are reduced. The ethylene-vinyl acetate copolymer provides toughness of the material, and ester groups in the molecular structure of the ethylene-vinyl acetate copolymer can greatly improve the affinity of a high molecular phase and zinc oxide particles, so that the interfacial binding force between the two phases is improved, and the interlayer binding strength of an SLS (Selective laser sintering) product is enhanced. The nano zinc oxide in the product has good dispersion, the grain diameter can be conveniently regulated and controlled between several microns and dozens of microns, the powder has good fluidity, and the product has good toughness.)

1. A high molecular composite powder for selective laser sintering is characterized in that: the powder particles are composed of continuous phase polystyrene, disperse phase ethylene-vinyl acetate copolymer and dispersed nano zinc oxide, and the particle size is several microns to tens of microns.

2. The preparation method of the polystyrene/zinc oxide composite powder for selective laser sintering according to claim 1, comprising the following process steps:

step a, adding and dissolving a toughening modifier, namely an ethylene-vinyl acetate copolymer and a flow aid, into monomer styrene, adding nano zinc oxide, and dispersing to obtain a monomer phase mixture; adding an initiator into the monomer phase mixture, uniformly stirring, and heating for reaction to obtain a prepolymerization mixture;

step b, adding an emulsifier into the prepolymerization mixture obtained in the step a, and uniformly stirring;

step c, dissolving a polymer dispersant and a monomer desolvation in water to obtain a water-phase solution;

d, adding the aqueous phase solution into the mixture obtained in the step b, and stirring until the mixture is in a stable oil-in-water emulsion state;

and e, heating for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain solid powder.

3. The method for preparing polystyrene/zinc oxide composite powder according to claim 2, wherein the monomer phase mixture consists of the following components in parts by weight: 30-50 parts of styrene, 0.5-1.5 parts of initiator, 1-9 parts of zinc oxide, 3-6 parts of ethylene-vinyl acetate copolymer and 0.2-0.5 part of flow promoter.

4. The method of claim 2, wherein the flow aid is one or more of paraffin wax, carnauba wax, polyethylene wax, and nano-silica.

5. The method of claim 2, wherein the initiator is azobisisobutyronitrile.

6. The method for preparing polystyrene/zinc oxide composite powder according to claim 2, wherein the heating reaction to obtain the pre-polymerization mixture is performed by: heating the mixture from room temperature to 55-60 ℃ at a heating rate of 0.25-0.30 ℃/min under a stirring state of 300-500 rpm, and reacting for 20-30 min.

7. The method for preparing the polystyrene/zinc oxide composite powder according to claim 2, wherein the emulsifier is composed of the following components in parts by weight: 0.7 part of Span-800.4, 6.2 parts of Tween-802.0 and 0.3 part of Op-0.6; the addition amount of the emulsifier is 8-12% of the monomer styrene.

8. The method for preparing the polystyrene/zinc oxide composite powder according to claim 2, wherein the aqueous phase solution comprises the following components in parts by weight: 200-250 parts of distilled water, 0.20 part of polyvinylpyrrolidone K300.10, 0.30 part of polyvinyl alcohol 17880.20, and 0.2-0.5 part of potassium chloride; the adding amount of the aqueous solution is 4-6 times of the amount of the monomer styrene.

9. The method for preparing polystyrene/zinc oxide composite powder according to claim 2, wherein the aqueous phase solution in the step d is added in a manner that: the stirring speed is 900-1200 r/min, the temperature of the reaction system is maintained at 60-65 ℃, and the stirring time is 30-40 min.

10. The method for preparing polystyrene/zinc oxide composite powder according to claim 2, wherein the reaction in the step e is carried out at 72-77 ℃ for 7-8 h, and the reaction is carried out at a stirring speed of 400-600 r/min.

11. The polystyrene/zinc oxide composite powder according to claim 1, which is used as a raw material for selective laser sintering molding in the field of additive manufacturing.

Technical Field

The invention relates to the technical field of materials for additive manufacturing, in particular to a preparation method of high-molecular composite powder for selective laser sintering.

Background

The additive manufacturing technology changes the cutting and assembling of raw materials of the traditional manufacturing technology into material accumulation, brings deep change to the traditional manufacturing industry, receives wide attention all over the world, and is widely applied to the fields of automobiles, aviation, aerospace, biomedical treatment, energy power and the like along with the development of the additive manufacturing technology. The raw material is the most important material base of the additive manufacturing technology and has a determining function on the forming and the use performance of the product. The high polymer material is the material with the largest consumption, the widest application range and the largest forming mode in additive manufacturing raw materials, and mainly comprises three forms of high polymer powder, high polymer wires and photosensitive resin. The high molecular powder has the advantages of small sintering energy, simple sintering process, good prototype quality and the like, and is widely applied to Selective Laser Sintering (SLS) molding. At present, the high polymer powder raw materials only comprise limited varieties of polystyrene, nylon, polycarbonate, polypropylene, polyethylene, polyether ether ketone, unsaturated polyester, phenolic resin and the like, wherein the polystyrene has the advantages of low price, low product molding shrinkage, good fluidity and the like, but the polystyrene belongs to a brittle material, has extremely low impact strength, can only be used as a low-end product with low requirements on strength, service life and durability, seriously restricts the application field of the polystyrene, and has small market share.

Polystyrene plastics are generally improved in brittleness by the addition of a toughening modifier component, but this method undoubtedly greatly increases the cost of later production of styrene powder by cryogenic grinding. On the other hand, the addition of inorganic particles with special efficacy can impart certain functions to the composite material and possibly simultaneously improve certain mechanical properties of the material. However, the nano particles have large specific surface area, more interface atoms and a large number of dangling bonds and unsaturated bonds, so that the nano particles have higher chemical activity and are easy to agglomerate to form a large-size weak connection interfaceLarge agglomerates. Meanwhile, the polarity difference exists between the inorganic nanoparticles and the organic matrix, so that the interface affinity is poor, and the performance of the material is reduced. Therefore, the problem of agglomeration of inorganic nanoparticles is solved, and the premise of obtaining the high-performance polymer nanocomposite is to improve the dispersibility of the nanoparticles in a polymer matrix phase. Researchers at home and abroad have tried to enhance the performance of SLS parts by adding nano-fillers to prepare composite materials. At present, the main methods for preparing the high-molecular nano composite powder material for SLS comprise a mechanical mixing method, a melt blending and cryogenic grinding method, a solvent precipitation method and the like. The mechanical mixing method is to mechanically mix the nano-filler and the polymer powder to obtain the composite powder, the method has simple process and low preparation cost, but because the nano-particles have large surface area and are easy to form agglomeration, the method can not avoid agglomeration of the nano-particles, so that the nano-filler in the obtained SLS part has poor dispersion effect in the polymer matrix。Therefore, Wangshoujie et al adopt a method of cooling liquid nitrogen and then crushing the liquid nitrogen at low temperature to obtain a polypropylene plastic powder mixed coupling agent to improve the dispersibility of hollow glass microspheres in a polymer matrix phase (a polypropylene powder product for selective laser sintering and a preparation method thereof, CN 110746693A). The melt blending and cryogenic grinding method is to use a double-screw extruder to melt blend and granulate, then use a cryogenic grinding device to carry out low-temperature grinding, drying, ball milling, screening and other processes on the granules to obtain the powder material suitable for SLS forming. The prepared powder particles of the composite material have larger shape difference and are not beneficial to powder paving of an SLS process, and the composite material is crushed into the powder material suitable for SLS forming at an extremely low temperature. The solvent precipitation method is to add polymer granules, nano powder filler and solvent into a reaction vessel, and in the process of dissolving and crystallizing matrix polymer, the matrix material is uniformly coated on the surface of the filler to form nano composite material powder. For example, a method (ZL 200710053667.8) for preparing nylon-reinforced shaped article by selective laser sintering uses nylon resin, mixed solvent, organized clay, antioxidant, etc. by heatingDissolving nylon resin in solvent, cooling, vacuum distilling and recovering solvent to obtain composite nylon/clay powder material. The method can uniformly disperse the nano material in the polymer matrix, and the obtained powder is mostly spherical or nearly spherical, so that the powder has good fluidity and the surface quality of an SLS part is high, but the problems of using a large amount of solvent and environmental pollution caused by the solvent exist.

Disclosure of Invention

Aiming at the problems that the prior polystyrene powder for SLS has large brittleness and the polymer nano-composite powder for SLS is prepared by the prior art, the invention provides a preparation method of the polymer nano-inorganic particle composite powder for SLS.

In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:

a preparation method of polymer nano inorganic particle composite powder for SLS comprises the following process steps:

step a, adding a toughening modifier and a flow aid into monomer styrene, dissolving, adding nano inorganic particles, and dispersing to obtain a monomer phase mixture; adding an initiator into the monomer phase mixture, uniformly stirring, and heating for reaction to obtain a prepolymerization mixture;

step b, adding an emulsifier into the prepolymerization mixture obtained in the step a, and uniformly stirring;

step c, dissolving a polymer dispersant and a monomer desolvation in water to obtain a water-phase solution;

d, adding the aqueous phase solution into the mixture obtained in the step b, and stirring until the mixture is in a stable oil-in-water emulsion state;

and e, heating for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain solid powder.

The preparation method of the polystyrene nanoparticle composite powder for SLS provided by the invention has a simple preparation process, and compared with the prior art, the preparation method has the advantages of low energy consumption, short time consumption, no use of organic solvent, good dispersibility of nano inorganic particles in a product in a polymer matrix phase, good powder particle size which can be regulated and controlled between several micrometers and dozens of micrometers by changing the concentration of an emulsifier, good powder fluidity and good product toughness.

In the invention, because the nano inorganic particles are dispersed in a liquid phase and then undergo a monomer polymerization reaction, and the surface of the nano inorganic particles is organized in a prepolymerization process, the nano particles in the obtained high molecular zinc oxide composite powder are uniformly dispersed in a high molecular matrix, and the dispersibility of the inorganic powder is a key factor for determining the performance of the high molecular inorganic composite powder for SLS. When inorganic particles with cleaning and sterilizing functions (such as zinc oxide as a photocatalytic semiconductor antibacterial agent) are adopted, the high-molecular composite powder is particularly suitable for SLS (selective laser sintering) molded medical products, food products, catering products, children toys and other products.

Preferably, the monomer phase mixture in step a consists of the following components in parts by weight: 30-50 parts of styrene, 0.5-1.5 parts of initiator, 1-9 parts of zinc oxide, 3-6 parts of ethylene-vinyl acetate copolymer and 0.2-0.5 part of flow promoter; the ethylene-vinyl acetate copolymer provides toughness of the material, and ester groups in the molecular structure of the ethylene-vinyl acetate copolymer can greatly improve the affinity of a high molecular phase and zinc oxide particles, so that the interfacial binding force between the high molecular phase and the zinc oxide particles is improved, and the interlayer binding strength of an SLS (Selective laser sintering) part is enhanced, so that the strength of the SLS part is improved. The nano zinc oxide in the components has the functions of sterilization and mildew resistance, and improves the thermal conductivity of the composite powder, thereby improving the absorption effect of the composite powder material on laser and reducing gaps among continuous layers of a workpiece.

Preferably, the flow aid is one or more of paraffin wax, carnauba wax, polyethylene wax and nano-silica.

Preferably, the initiator is azobisisobutyronitrile.

Preferably, the emulsifier in the step b consists of the following components in parts by weight: 0.7 part of Span-800.4, 6.2 parts of Tween-802.0 and 0.3 part of Op-0.6. The addition amount of the emulsifier is 8-12% of the monomer styrene. The emulsifier forms a transition layer from oleophylic to hydrophilic on the surface of the monomer phase, so that the emulsifying effect is improved, the stability of dispersed liquid drops is improved, and the particle size of product powder can be regulated and controlled between several micrometers and dozens of micrometers by changing the concentration of the emulsifier. The particle size of the product has an important influence on SLS molded parts, when the particle size of the powder is reduced, the SLS molded parts can be printed under smaller slice thickness, so that higher molding precision can be obtained, and the surface quality of the molded parts is improved due to the fact that the flatness of single-layer powder spreading is improved. However, the energy consumption and the cost are greatly increased when the particle size of the product is reduced by the traditional cryogenic grinding technology, and the invention can conveniently obtain the powder with small particle size by regulating and controlling the concentration of the emulsifier.

Preferably, the aqueous phase solution in step c consists of the following components in parts by weight: 200-250 parts of distilled water, 0.20 part of polyvinylpyrrolidone K300.10, 0.30 part of polyvinyl alcohol 17880.20, and 0.2-0.5 part of potassium chloride. The adding amount of the aqueous solution is 4-6 times of the amount of the monomer styrene.

Preferably, the heating reaction to obtain the pre-polymerization mixture is carried out by: heating the mixture from room temperature (25 ℃) to 55-60 ℃ at a heating rate of 0.25-0.30 ℃/min under the stirring state of 300-500 rpm, and reacting for 20-30 min. In the process, the surface of the nano zinc oxide particle is combined with polar EVA molecules through intermolecular force or free radical initiation, or forms surface grafting with styrene monomer through free radical initiation, so that the surface of the zinc oxide particle is organized.

Preferably, the specific operation of adding the emulsifier in the step b is as follows: and uniformly mixing the emulsifier with the formula amount, adding the emulsifier at the stirring speed of 300-500 rpm, and stirring for 20-30 min.

Preferably, the operation mode of adding the aqueous phase solution in the step d is as follows: the stirring speed is 900-1200 r/min, the temperature of the reaction system is maintained at 60-65 ℃, and the stirring time is 30-40 min. In the process, the reaction system is changed from a single oil phase to an oil-in-water system, and the droplet diameter of the dispersed oil phase droplet can be regulated and controlled within the range of several micrometers to dozens of micrometers according to the proportion and the dosage of the emulsifier and the dispersant and the different stirring speeds.

Preferably, the reaction conditions in step e are as follows: the temperature is 72-77 ℃, the reaction time is 6-8 h, and the reaction is carried out at a stirring speed of 400-.

Drawings

Fig. 1 and 2 are electron micrographs of the test example 1. FIG. 1 is a scanning transmission electron micrograph of a polystyrene/nano zinc oxide composite powder obtained in an example of the present invention, and FIG. 2 is a TEM photograph of a polystyrene powder obtained in a comparative example.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The embodiment of the invention provides a preparation method of polymer composite powder for selective laser sintering, which comprises the following process steps:

a. adding 20g of ethylene-vinyl acetate copolymer (product of Mitsui corporation, Japan, with VA content of 40%) into 200g of styrene monomer to dissolve, adding 1.2g of paraffin (No. 54) and 15g of nano zinc oxide, and performing ultrasonic dispersion for 25min to obtain a mixture; then adding 4g of azodiisobutyronitrile, stirring the mixture at 500r/min, simultaneously heating to 55 ℃ at 0.3 ℃/min, and then preserving the temperature for 30min to obtain a prepolymerization mixture;

b. adding 3g of Span-80, 16g of Tween-80 and 2.5g of Op-10 into the mixture, and stirring for 20 min;

c. heating to 65 ℃, increasing the rotating speed to 1200r/min, and adding an aqueous phase solution consisting of 1100g of distilled water, 1.5g of potassium chloride, 1.25g of polyvinyl alcohol 1788 and 0.75g of polyvinylpyrrolidone K30;

d. stirring for 40min, reducing the stirring speed to 500r/min, heating to 75 ℃, reacting for 7 hours, centrifugally separating, washing and drying to obtain the catalyst.

Example 2

The embodiment of the invention provides a preparation method of polymer composite powder for selective laser sintering, which comprises the following process steps:

a. adding 30g of ethylene vinyl acetate copolymer (product of Mitsui corporation, Japan, the VA content is 40%) and 1g of carnauba wax (No. 54) into 200g of monomer styrene, uniformly mixing, adding 36g of nano zinc oxide, ultrasonically dispersing for 30min to obtain a mixture, adding 6g of azodiisobutyronitrile, stirring the mixture at 400r/min, simultaneously heating to 55 ℃ at 0.25 ℃/min, and keeping the temperature for 30min under stirring to obtain a prepolymerization mixture;

b. uniformly mixing 2g of Span-80, 12g of Tween-80 and 2g of Op-10, adding the mixture into the prepolymerization mixture, and stirring for 30min at the stirring speed of 600 r/min;

c. heating to 65 ℃, increasing the rotating speed to 100r/min, and adding an aqueous phase solution consisting of 900g of distilled water, 2g of potassium chloride, 1g of polyvinyl alcohol 1788 and 0.75g of polyvinylpyrrolidone K30;

d. stirring for 25min, reducing the stirring speed to 600r/min, heating to 72 ℃, reacting for 8 hours, centrifugally separating, washing and drying to obtain the catalyst.

Example 3

The embodiment of the invention provides a preparation method of polymer composite powder for selective laser sintering, which comprises the following process steps:

a. adding 36g of ethylene vinyl acetate copolymer (product of Mitsui corporation, Japan, the VA content is 40%), 1.2g of paraffin (No. 54) and 1g of polyethylene wax (BAKER HUGHES Polywax 400) into 250g of monomer styrene, uniformly mixing, adding 12.0g of nano zinc oxide, performing ultrasonic dispersion for 20min to obtain a mixture, adding 2.5g of azodiisobutyronitrile, stirring at 400r/min, heating to 60 ℃ at 0.25 ℃/min, and keeping the temperature for 20min under stirring to obtain a prepolymerization mixture;

b. uniformly mixing 3.5g of Span-80, 25g of Tween-80 and 1.5g of Op-10, adding the mixture into the prepolymerization mixture, and stirring for 30min at the stirring speed of 400 r/min;

c. increasing the rotation speed to 900r/min, and adding an aqueous phase solution consisting of 1000g of distilled water, 2.5g of potassium chloride, 1.5g of polyvinyl alcohol 1788 and 1g of polyvinylpyrrolidone K30;

d. stirring for 20min, reducing the stirring speed to 400r/min, heating to 77 ℃, reacting for 6 hours, centrifugally separating, washing and drying to obtain the catalyst.

Example 4

The embodiment of the invention provides a preparation method of polymer composite powder for selective laser sintering, which comprises the following process steps:

a. adding 25g of ethylene vinyl acetate copolymer (a product of Mitsui corporation, Japan, the VA content is 40%), 1g of carnauba wax and 1g of polyethylene wax (BAKER HUGHES Polywax 400) into 220g of monomer styrene, uniformly mixing, adding 22g of nano zinc oxide, performing ultrasonic dispersion for 30min to obtain a mixture, adding 6g of azodiisobutyronitrile, stirring the mixture at 450r/min, heating to 55 ℃ at 0.25 ℃/min, and keeping the temperature for 30min under stirring to obtain a prepolymerization mixture;

b. uniformly mixing 2g of Span-80, 14g of Tween-80 and 2g of Op-10, adding the mixture into the prepolymerization mixture, and stirring for 30min at the stirring speed of 600 r/min;

c. heating to 65 ℃, increasing the rotating speed to 1000r/min, and adding an aqueous phase solution consisting of 1100g of distilled water, 1g of potassium chloride, 1.2g of polyvinyl alcohol 1788 and 0.8g of polyvinylpyrrolidone K30;

d. stirring for 25min, reducing the stirring speed to 600r/min, heating to 75 ℃, reacting for 7.5 hours, centrifugally separating, washing and drying to obtain the catalyst.

Example 5

The embodiment of the invention provides a preparation method of polymer composite powder for selective laser sintering, which comprises the following process steps:

a. adding 24g of ethylene-vinyl acetate copolymer (product of Mitsui corporation, Japan, the VA content is 40%) and 1g of paraffin (No. 54) into 150g of monomer styrene, uniformly mixing, adding 3g of nano zinc oxide, ultrasonically dispersing for 30min to obtain a mixture, adding 4g of azobisisobutyronitrile, stirring the mixture at 500r/min, simultaneously heating to 55 ℃ at 0.25 ℃/min, and then keeping the temperature for 25min under stirring to obtain a prepolymerization mixture;

b. uniformly mixing 2.2g of Span-80, 13g of Tween-80 and 2.4g of Op-10, adding the mixture into the prepolymerization mixture, and stirring for 30min at the stirring speed of 600 r/min;

c. heating to 65 ℃, increasing the rotating speed to 1200r/min, and adding an aqueous phase solution consisting of 900g of distilled water, 0.8g of potassium chloride, 1.2g of polyvinyl alcohol 1788 and 1g of polyvinylpyrrolidone K30;

d. stirring for 35min, reducing the stirring speed to 600r/min, heating to 75 ℃, reacting for 7.5 hours, centrifugally separating, washing and drying to obtain the catalyst.

Comparative example

a. Adding 0.8g of azobisisobutyronitrile into 200g of monomer styrene, stirring the mixture at 400r/min, heating to 60 ℃ at 0.25 ℃/min, and then keeping the temperature for 20min under stirring to obtain a prepolymerization mixture;

b. adding 2.4g of Span-80, 12g of Tween-80 and 2.5g of Op-10 into the mixture, and stirring for 20 min;

c. heating to 65 ℃, increasing the rotating speed to 1200r/min, and adding an aqueous phase solution consisting of 1250g of distilled water, 1.5g of potassium chloride, 1.25g of polyvinyl alcohol 1788 and 0.75g of polyvinylpyrrolidone K30;

d. stirring for 30min, reducing the stirring speed to 500r/min, heating to 75 ℃, reacting for 7 hours, centrifugally separating, washing and drying to obtain the catalyst.

Test example 1

The performance test of the styrene/nano zinc oxide composite powder or polystyrene powder prepared in examples 1 to 5 and comparative example 1 was carried out:

(1) the powder particle size was measured (using a particle counter (RC-2100) from Oume Kerr technology Co., Ltd., and the results are shown in Table 1.

TABLE 1 measurement of the particle size of the powders

Sample (I)	Example 1	Example 2	Example 3	Example 4	Example 5	Comparative example
							Coefficient of dispersion/%)	44.44	55.91	33.21	29.07	33.23	40.29
Standard deviation/. mu.m	2.69	5.91	5.15	5.76	2.89	1.71
							D2/μm	11.95	23.17	30.56	31.19	15.35	8.76
D50/μm	6.04	9.50	14.54	19.70	9.44	3.92
							D98/μm	2.21	8.56	7.81	6.92	4.06	2.18
Average particle diameter/. mu.m	6.06	10.57	11.15	8.82	9.55	4.24
							Volume average particle diameter/. mu.m	12.30	18.13	15.51	19.81	13.37	6.53

(2) The polystyrene/nano zinc oxide composite powder particles prepared by the embodiment of the invention are subjected to transmission electron microscope test, and a sample is embedded and cured by epoxy resin and dyed by phosphotungstic acid, and the slice thickness is 60 nm. The TEM micrograph is shown in FIG. 1, and it can be seen that the powder particle microscopic morphology comprises a three-phase structure, namely a polystyrene continuous phase in a light color region, an ethylene vinyl acetate copolymer dispersed phase in a dark color region, and nano zinc oxide particles dispersed substantially in a particle state. The invention can obviously improve the dispersibility of the nano zinc oxide in the polymer base phase.

And (3) carrying out transmission electron microscope test on the polystyrene powder particles prepared in the comparative example, and carrying out embedding, curing and phosphotungstic acid staining on a sample with the slice thickness of 60 nm. The TEM photograph is shown in FIG. 2. The powder particle morphology can be seen as a single phase structure.

(3) SLS moldability test

SLS molding was performed on the polystyrene/nano-zinc oxide composite powder obtained in examples 1 to 5, and the laser type was continuous CO₂The laser device with the wavelength of 10.6 mu m sets the laser power of 26W, the scanning speed of 1100mm/s, the powder spreading thickness of 0.1mm, the scanning interval of 0.1mm and the preheating temperature of 95 ℃. The results show that the sintered samples of the powders obtained in examples 1 to 5 had good molding accuracy and no warpage.

Test example 2

After the polystyrene/nano-zinc oxide composite powder obtained in examples 1 to 5 and the polystyrene powder SLS obtained in the comparative example were molded, the impact strength was tested according to GB/T1843-2008 using a cantilever beam impact tester (SMT-3002I, saisson detection equipment limited, nj), with a sample size of 80 mm '10 mm' 4 mm and a notch depth of 2 mm.

TABLE 2 impact Strength of sintered samples of polystyrene/nano-zinc oxide composite powder obtained in examples 1 to 5 and polystyrene powder obtained in comparative example

Sample (I)	Example 1	Example 2	Example 3	Example 4	Example 5	Comparative example
							Impact Strength (KJ/m)2）	10.67	7.67	13.04	9.57	14.92	3.98

As can be seen from Table 2, the impact strength of the polystyrene/nano zinc oxide composite powder material of the embodiment of the invention is significantly better than that of pure polystyrene.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.