Photocuring composite material for 3D printing lightweight structure, preparation method of photocuring composite material and 3D printing product

Abstract

The invention belongs to the technical field of 3D printing materials, and particularly relates to a photocuring composite material for 3D printing of a lightweight structure, a preparation method of the photocuring composite material and a 3D printing product. Compared with the prior art, the solid epoxy resin foam balls are used as a lightweight framework to replace traditional fragile hollow microspheres, and low density and high pressure resistance are both considered; meanwhile, the solid epoxy resin foam ball is subjected to dual modification by plasma and a silane coupling agent, so that the interface bonding force between the foam ball and resin is remarkably improved; in addition, through synergistic enhancement of the light-cured resin matrix and the nano reinforced filler, a compact network is formed, gaps of foam balls are filled, and the bending strength of the composite material is improved by 80%.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing materials technology, and particularly relates to a photocurable composite material for 3D printing lightweight structures, its preparation method, and 3D printed products. Background Technology

[0002] With the continuous advancement of technology and the rapid development of the manufacturing industry, traditional manufacturing methods are facing enormous challenges. Traditional metal manufacturing processes often encounter problems such as high processing difficulty, high cost, and long cycle time when manufacturing complex and lightweight structures. 3D printing technology, as an emerging manufacturing technology, has advantages such as flexible design, rapid manufacturing, and low cost, and is gradually becoming an important means of achieving lightweight design and application in the manufacturing industry.

[0003] Traditional 3D printing photopolymer materials use polymers such as acrylates and epoxy resins as the matrix. Because the resin matrix itself has a high density (typically 1.1~1.3 g / cm³),... 3 The dense molecular chains and lack of natural porous structure make it difficult to reduce the density of the material after curing, thus failing to meet the requirements for lightweighting.

[0004] In existing technologies, hollow microspheres (such as glass microspheres) can be added to 3D photocurable materials as fillers to reduce material density, but the following problems still exist: 1) Hollow structures are easily broken under shear force, resulting in a decrease in the strength of printed parts; 2) Poor interfacial bonding with the resin matrix and low interlayer peel strength (<0.5MPa); 3) High porosity (>5%) affects dimensional accuracy. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a photocurable composite material for 3D printing lightweight structures, a method for preparing the same, and 3D printed products. The photocurable composite material uses solid epoxy resin foam balls as fillers and can combine lightweight and compressive strength.

[0006] This invention provides a photopolymerizable composite material for 3D printing lightweight structures, comprising:

[0007] 100-200 parts by weight of modified solid epoxy resin foam balls;

[0008] 50-100 parts by weight of UV-curable resin matrix;

[0009] 5-15 parts by weight of nano-reinforced filler;

[0010] 1-5 parts by weight of photoinitiator;

[0011] The modified solid epoxy resin foam ball is obtained by modifying solid epoxy resin foam balls; the modification process includes plasma treatment and silane coupling agent modification.

[0012] The solid epoxy resin foam ball includes a core and a covering layer surrounding the core; the core is a foam ball; the covering layer includes a composite layer and an epoxy resin protective layer; the composite layer includes alternating epoxy resin layers and powder layers; the epoxy resin layers in the composite layer are in contact with the foam ball; the epoxy resin protective layer is disposed on the surface of the composite layer away from the foam ball; the powder layer includes chopped fibers and hollow glass microspheres.

[0013] The viscosity of the photocurable resin matrix at 25°C is 200~700 cP.

[0014] Preferably, the epoxy resin layer and the epoxy resin protective layer in the composite layer each independently comprise cured epoxy resin adhesive.

[0015] The epoxy resin compound comprises bisphenol A epoxy resin and an amine curing agent;

[0016] The mass ratio of the bisphenol A epoxy resin to the amine curing agent is 10:(1~5).

[0017] And / or, the mass ratio of the chopped fibers to the hollow glass microspheres is (5~15):1;

[0018] And / or, the diameter of the chopped fibers is 9~13 μm and the length of the chopped fibers is 3~10 mm;

[0019] The hollow glass microspheres have a particle size of 10~50 μm and a density of 0.2~0.3 g / cm³. 3 .

[0020] Preferably, the bisphenol A type epoxy resin has an epoxy value of 0.48~0.54 mol / 100 g;

[0021] And / or, the amine curing agent is selected from diaminodiphenylmethane and isophorone diamine; the mass ratio of diaminodiphenylmethane to isophorone diamine is (1~3):1;

[0022] And / or the type of chopped fiber is glass fiber.

[0023] Preferably, the porosity of the solid epoxy resin foam balls is less than 1%;

[0024] And / or, the density of the solid epoxy resin foam balls is 0.25~0.35 g / cm³. 3 ;

[0025] And / or, the particle size of the solid epoxy resin foam balls is 0.5~2 mm;

[0026] And / or, the particle size of the nano-reinforced filler is 20~50 nm;

[0027] And / or, the photocurable resin matrix is ​​selected from acrylate resins; the functionality of the acrylate resin is 2 to 8.

[0028] Preferably, the photocurable resin matrix is ​​selected from polyurethane acrylate and / or epoxy acrylate;

[0029] And / or, the nano-reinforcing filler is selected from one or more of nano-silica, carbon nanotubes, nano-silica treated with silane coupling agent and carbon nanotubes treated with silane coupling agent;

[0030] And / or, the photoinitiator is selected from acylphosphine oxide photoinitiators.

[0031] Preferably, the gas used for plasma treatment is a mixture of argon and oxygen; the volume ratio of argon to oxygen is (2~6):1;

[0032] The power of the plasma treatment is 50~200 W;

[0033] The plasma treatment time is 5-20 minutes;

[0034] The silane coupling agent used for the silane coupling agent modification is selected from aminosilane coupling agents.

[0035] The present invention also provides a method for preparing the above-mentioned photocurable composite material for 3D printing lightweight structures, comprising the following steps:

[0036] A photocurable resin matrix, nano-reinforcing filler, and photoinitiator were mixed and stirred, and then modified solid epoxy resin foam balls were added and ultrasonically dispersed to obtain a photocurable composite material for 3D printing lightweight structures.

[0037] Preferably, the mixing and stirring speed is 1000~2000 r / min;

[0038] The mixing and stirring time is 10~30 min;

[0039] The power of the ultrasonic dispersion is 10~100 kHz;

[0040] The ultrasonic dispersion time is 5~30 min.

[0041] This invention provides a 3D printed product, which is obtained by printing and curing the above-mentioned photopolymer composite material for 3D printing lightweight structures.

[0042] Preferably, the thickness of the printed layer is 50~100 μm, and the exposure time is 5~15 s / layer;

[0043] The curing temperature is 60~100℃; the curing time is 1~3 h.

[0044] Compared with existing technologies, this invention uses solid epoxy resin foam balls as a lightweight skeleton to replace traditional fragile hollow microspheres, taking into account both low density and high compressive strength. At the same time, the solid epoxy resin foam balls are modified by plasma and silane coupling agent, which significantly improves the interfacial bonding force between the foam balls and the resin. In addition, the photocurable resin matrix and nano-reinforcing fillers are synergistically reinforced to form a dense network that fills the gaps between the foam balls, thereby increasing the flexural strength of the composite material by 80%. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] This invention provides a photocurable composite material for 3D printing lightweight structures, comprising: 100-200 parts by weight of modified solid epoxy resin foam spheres; 50-100 parts by weight of photocurable resin matrix; 5-15 parts by weight of nano-reinforcing filler; and 1-5 parts by weight of photoinitiator. The modified solid epoxy resin foam spheres are obtained by modifying solid epoxy resin foam spheres. The modification treatment includes plasma treatment and silane coupling agent modification. The solid epoxy resin foam spheres include a core and a coating layer covering the core. The core is a foam sphere. The coating layer includes a composite layer and an epoxy resin protective layer. The composite layer includes alternating epoxy resin layers and powder layers. The epoxy resin layers in the composite layer are in contact with the foam spheres. The epoxy resin protective layer is disposed on the surface of the composite layer away from the foam spheres. The powder layer includes chopped fibers and hollow glass microspheres. The viscosity of the photocurable resin matrix at 25°C is 200-700 cP.

[0047] In one specific embodiment of the present invention, optionally, the content of the modified solid epoxy resin foam balls in the photocurable composite material is 100 parts by weight, 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 150 parts by weight, 160 parts by weight, 170 parts by weight, 180 parts by weight, 190 parts by weight, 200 parts by weight, or any two of the above values.

[0048] In one specific embodiment of the present invention, the modified solid epoxy resin foam ball is obtained by modifying solid epoxy resin foam balls.

[0049] In one specific embodiment of the present invention, the particle size of the solid epoxy resin foam balls is preferably 0.5 to 2 mm; optionally, the particle size of the solid epoxy resin foam balls is 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, or any two of the above values.

[0050] In a specific embodiment of the present invention, the modification treatment includes plasma treatment and silane coupling agent modification; the gas used for plasma treatment is a mixture of argon and oxygen; the volume ratio of argon to oxygen is preferably (2~6):1; optionally, the volume ratio of argon to oxygen is 2:1, 3:1, 4:1, 5:1, 6:1 or any two of the above ratios; the power of the plasma treatment is preferably 50~200 W; optionally, the power of the plasma treatment is 50 W, 80 W, 100 W, 120 W, 150 W, 180 W, 200 W or any two of the above values; the time of the plasma treatment is preferably 5~20 min; optionally, the time of the plasma treatment is 5 min, 10 min, 15 min, 20 min, or 5 min. The value is min or within the range of any two of the above values; the silane coupling agent used for the silane coupling agent modification is preferably an aminosilane coupling agent, including, but not limited to, one or more of γ-aminopropyltriethoxysilane (KH550), γ-aminopropyltrimethoxysilane (KH540), N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792), and N-β-aminoethyl-γ-aminopropyltriethoxysilane (KH602). By subjecting solid epoxy resin foam balls to dual modification with plasma and silane coupling agents, their surface energy can be reduced to 25 mN / m, thereby improving the fluidity of the slurry.

[0051] In a specific embodiment of the present invention, the modified solid epoxy resin foam balls are prepared according to the following steps: the solid epoxy resin foam balls are subjected to plasma treatment, then immersed in an ethanol solution containing a silane coupling agent, and dried to obtain modified solid epoxy resin foam balls; the mass concentration of the silane coupling agent in the ethanol solution containing the silane coupling agent is preferably 0.5% to 3%; optionally, the mass concentration of the silane coupling agent in the ethanol solution containing the silane coupling agent is 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, or any two of the above values; the immersion time is preferably 10 to 60 min; optionally, the immersion time is 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or any two of the above values; the drying temperature is preferably 60℃ to 80℃.

[0052] In one specific embodiment of the present invention, the solid epoxy resin foam ball includes a core and a covering layer surrounding the core; the core is a foam ball; the foam ball is preferably a polystyrene foam ball; the particle size of the polystyrene foam ball is preferably 0.1~0.3 mm, more preferably 0.2 mm; the density of the polystyrene foam ball is preferably 0.01~0.05 g / cm³. 3 Optionally, the polystyrene foam balls have a density of 0.01 g / cm³. 3 0.02 g / cm 3 0.03 g / cm 3 0.04 g / cm 3 0.05 g / cm 3 Or the range between any two of the above values.

[0053] In a specific embodiment of the present invention, the coating layer includes a composite layer and an epoxy resin protective layer; the composite layer includes alternating epoxy resin layers and powder layers; the epoxy resin layers are disposed on the surface of the composite layer away from the foam balls to cover the outermost powder layer of the composite layer to form a protective layer; the epoxy resin layers in the composite layer are in contact with the foam balls, that is, the innermost epoxy resin layer in the composite layer is in contact with the foam balls; the epoxy resin layers and the epoxy resin protective layer in the composite layer each independently include cured epoxy resin adhesive; the epoxy resin adhesive includes bisphenol A epoxy resin and an amine curing agent; the mass ratio of the bisphenol A epoxy resin to the amine curing agent is preferably 10:(1~5); optionally, the mass ratio of the bisphenol A epoxy resin to the amine curing agent is 10:1, 10:2, 10:3, 10:4, 10:5 or any two of the above values.

[0054] In a specific embodiment of the present invention, the epoxy value of the bisphenol A type epoxy resin is preferably 0.48~0.54 mol / 100 g; optionally, the epoxy value of the bisphenol A type epoxy resin is 0.48 mol / 100 g, 0.49 mol / 100 g, 0.50 mol / 100 g, 0.51 mol / 100 g, 0.52 mol / 100 g, 0.53 mol / 100 g, 0.54 mol / 100 g, or a range between any two of the above values.

[0055] In one specific embodiment of the present invention, the amine curing agent is selected from diaminodiphenylmethane and isophorone diamine; the mass ratio of diaminodiphenylmethane to isophorone diamine is preferably (1~3):1; optionally, the mass ratio of diaminodiphenylmethane to isophorone diamine is 1:1, 1.5:1, 2:1, 2.5:1, 3:1 or any two of the above ratios.

[0056] In one specific embodiment of the present invention, the epoxy resin layer further includes a toughening agent; the mass of the toughening agent is preferably 1% to 5% of the mass of the epoxy resin compound; optionally, the mass of the toughening agent is 1%, 2%, 3%, 4%, 5% of the mass of the epoxy resin compound, or a range between any two of the above values; the type of the toughening agent is preferably EVA (ethylene-vinyl acetate copolymer); the molecular weight of the EVA is preferably 100,000 to 20,000 g / mol; optionally, the molecular weight of the EVA is preferably 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, 160,000 g / mol, 170,000 g / mol, 180,000 g / mol, 190,000 g / mol, or 20,000 g / mol. g / mol or a range between any two of the above values; the mass content of VA in the EVA is preferably 8% to 15%; optionally, the mass content of VA in the EVA is preferably 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or a range between any two of the above values.

[0057] In one specific embodiment of the present invention, the powder layer is bonded and fixed by an epoxy resin layer; the powder layer includes chopped fibers and hollow glass microspheres; the preferred mass ratio of the chopped fibers to the hollow glass microspheres is (5~15):1; optionally, the mass ratio of the chopped fibers to the hollow glass microspheres is 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1 or any two of the above values.

[0058] In one specific embodiment of the present invention, the diameter of the chopped fiber is 9~13 μm; optionally, the diameter of the chopped fiber is 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or any two of the above values; the length of the chopped fiber is 3~10 mm; optionally, the length of the chopped fiber is 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or any two of the above values.

[0059] In one specific embodiment of the present invention, the type of chopped fiber is preferably glass fiber.

[0060] In one specific embodiment of the present invention, the particle size of the hollow glass microspheres is preferably 10~50 μm; optionally, the particle size of the hollow glass microspheres is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, or any two of the above values; the density of the hollow glass microspheres is preferably 0.2~0.3 g / cm³. 3 More preferably 0.25 g / cm³ 3 .

[0061] In one specific embodiment of the present invention, one epoxy resin layer and one powder layer constitute one cycle, and the number of cycles of alternating epoxy resin layers and powder layers in the coating layer is preferably 10 to 50; optionally, the number of cycles is 10, 20, 30, 40, 50 or an integer range between any two of the above values.

[0062] In one specific embodiment of the present invention, the porosity of the solid epoxy resin foam ball is less than 1%.

[0063] In one specific embodiment of the present invention, the density of the solid epoxy resin foam balls is preferably 0.25~0.35 g / cm³. 3 Optionally, the density of the solid epoxy resin foam balls is 0.25 g / cm³. 3 0.26 g / cm 3 0.27 g / cm3 0.28 g / cm 3 0.29 g / cm 3 0.30 g / cm 3 0.31 g / cm 3 0.32 g / cm 3 0.33 g / cm 3 0.34 g / cm 3 0.35 g / cm 3 Or the range between any two of the above values.

[0064] In a specific embodiment of the present invention, the solid epoxy resin foam ball is preferably prepared by the following method: S1) providing liquid raw materials and powder raw materials; the liquid raw materials include epoxy resin adhesive and diluent; the powder raw materials include chopped fibers and hollow glass microspheres; S2) under stirring conditions, the liquid raw materials and powder raw materials are alternately sprayed onto the surface of the foam ball and cured to obtain a solid epoxy resin foam ball.

[0065] In one specific embodiment of the present invention, the diluent is any epoxy diluent well known to those skilled in the art, and there are no special limitations. It can be an active diluent or a non-active diluent. The active diluent includes, but is not limited to, one or more of allyl glycidyl ether, butyl glycidyl ether, propylene oxide butyl ether, and diethylene glycol monovinyl ether. The non-active diluent includes, but is not limited to, acetone, xylene, toluene, ethyl acetate, etc. The mass of the diluent is preferably 5% to 15% of the mass of the epoxy resin adhesive. Optionally, the mass of the diluent is 5%, 8%, 9%, 10%, 12%, 15% of the mass of the epoxy resin adhesive, or a range between any two of the above values.

[0066] In a specific embodiment of the present invention, the liquid raw material is preferably prepared by the following method: mixing and stirring an epoxy resin compound with a diluent to obtain a liquid raw material; the stirring speed is preferably 1000~3000 r / min; optionally, the stirring speed is 1000 r / min, 1200 r / min, 1500 r / min, 1600 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2500 r / min, 2600 r / min, 2800 r / min, 3000 r / min or any two of the above values; the stirring time is preferably 1~10 min; optionally, the stirring time is 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or any two of the above values.

[0067] In a specific embodiment of the present invention, the epoxy resin compound is prepared by the following method: bisphenol A epoxy resin and an amine curing agent are stirred at high speed to obtain the epoxy resin compound; the temperature of the high-speed stirring is preferably 20℃~30℃, more preferably 25℃; the speed of the high-speed stirring is preferably 1000~3000 r / min; optionally, the speed of the high-speed stirring is 1000 r / min, 1200 r / min, 1500 r / min, 1600 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2500 r / min, 2600 r / min, 2800 r / min, 3000 r / min or any two of the above values; the time of the high-speed stirring is preferably 5~30 min; optionally, the time of the high-speed stirring is 5 min, 10 min, 15 min, 20 min, 25 min, 30 min or any two of the above values.

[0068] In a specific embodiment of the present invention, the powder raw material is preferably prepared by the following method: short-cut fibers and hollow glass microspheres are obtained by high-speed stirring; the high-speed stirring speed is preferably 2000~4000 r / min; optionally, the high-speed stirring speed is 2000 r / min, 2200 r / min, 2500 r / min, 2600 r / min, 2800 r / min, 3000 r / min, 3200 r / min, 3500 r / min, 3600 r / min, 3800 r / min, 4000 r / min or any two of the above values; the high-speed stirring time is preferably 10~60 min; optionally, the mixing and stirring time is 10 min, 20 min, 30 min, 40 min, 50 min, 60 min or any two of the above values.

[0069] In a specific embodiment of the present invention, under stirring conditions, liquid raw materials and powder raw materials are alternately sprayed onto the surface of foam balls; the stirring speed is preferably 10~60 r / min; optionally, the stirring speed is 10 r / min, 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min or any two of the above values; the flow rate of the liquid raw material spraying is preferably 100~200 mL / min; optionally, the flow rate of the liquid raw material spraying is 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 170 mL / min, 180 mL / min, 190 mL / min, 200 mL / min or any two of the above values; the spraying time of each liquid raw material is preferably 3~8 min; optionally, the spraying time of each liquid raw material is 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, or 9 min. The spraying flow rate of the powder material is preferably 200~600 g / min; optionally, the spraying flow rate of the powder material is 200 g / min, 300 g / min, 400 g / min, 500 g / min, 600 g / min or any two of the above values; the spraying time of each powder material is preferably 5~10 min; optionally, the spraying time of each powder material is 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or any two of the above values.

[0070] In a specific embodiment of the present invention, one cycle is defined as spraying one liquid material and one powder material. During the alternating spraying process, vacuum treatment is preferably performed once every 5 to 15 cycles, more preferably once every 8 to 11 cycles, and even more preferably once every 10 cycles. The pressure of the vacuum treatment is preferably 0.1 MPa. The time of the vacuum treatment is preferably 10 to 30 minutes. Optionally, the time of the vacuum treatment is 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or any two of the above values.

[0071] In one specific embodiment of the present invention, the curing temperature is preferably 70℃~100℃; optionally, the curing temperature is 70℃, 80℃, 90℃, 100℃ or any two of the above values; the curing time is preferably 3~10 h; optionally, the curing time is 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or any two of the above values.

[0072] In one specific embodiment of the present invention, optionally, the content of the photocurable resin matrix in the photocurable composite material is 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, or any two of the above values.

[0073] In one specific embodiment of the present invention, optionally, the viscosity of the photocurable resin matrix at 25°C is 200 cP, 250 cP, 300 cP, 350 cP, 400 cP, 450 cP, 500 cP, 550 cP, 600 cP, 650 cP, 700 cP, or any two of the above values.

[0074] In one specific embodiment of the present invention, the photocurable resin matrix is ​​selected from acrylate resins; the functionality of the acrylate resin is preferably 2 to 8; optionally, the functionality of the acrylate resin is 2, 3, 4, 5, 6, 7 or 8.

[0075] In one specific embodiment of the present invention, the photocurable resin matrix is ​​preferably polyurethane acrylate and / or epoxy acrylate. In the embodiments provided by the present invention, hexafunctional polyurethane acrylate R2601 is specifically used as an example for illustration.

[0076] In one specific embodiment of the present invention, optionally, the content of the nano-reinforced filler in the photocurable composite material is 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, or any two of the above values.

[0077] In one specific embodiment of the present invention, the particle size of the nano-reinforced filler is preferably 20-50 nm; optionally, the particle size of the nano-reinforced filler is 20 nm, 30 nm, 40 nm, 50 nm or any two of the above values.

[0078] In one specific embodiment of the present invention, the nano-reinforcing filler is preferably one or more of nano-silica, carbon nanotubes, nano-silica treated with silane coupling agent, and carbon nanotubes treated with silane coupling agent.

[0079] In one specific embodiment of the present invention, the silane coupling agent used in the nano-silica treated with the silane coupling agent and the carbon nanotube treated with the silane coupling agent are each preferably aminosilane coupling agents, including, but not limited to, one or more of γ-aminopropyltriethoxysilane (KH550), γ-aminopropyltrimethoxysilane (KH540), N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792) and N-β-aminoethyl-γ-aminopropyltriethoxysilane (KH602).

[0080] In one specific embodiment of the present invention, the content of the photoinitiator in the photocurable composite material is 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, or any two of the above values.

[0081] In one specific embodiment of the present invention, the photoinitiator is preferably a benzoyl free radical photoinitiator, more preferably an acylphosphine oxide photoinitiator, and even more preferably 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO).

[0082] In one specific embodiment of the present invention, the viscosity of the photocurable composite material used for 3D printing lightweight structures is preferably 300~800 cP to meet the requirements of DLP printing; optionally, the viscosity of the photocurable composite material used for 3D printing lightweight structures is 300 cP, 400 cP, 500 cP, 600 cP, 700 cP, 800 cP or any two of the above values.

[0083] This invention uses solid epoxy resin foam balls as a lightweight skeleton to replace traditional fragile hollow microspheres, taking into account both low density and high compressive strength. At the same time, the solid epoxy resin foam balls are modified by plasma and silane coupling agent, which significantly improves the interfacial bonding force between the foam balls and the resin. In addition, the photocurable resin matrix and nano-reinforcing fillers are synergistically reinforced to form a dense network, filling the gaps between the foam balls, thereby increasing the flexural strength of the composite material by 80%.

[0084] The present invention also provides a method for preparing the above-mentioned photocurable composite material for 3D printing lightweight structures, comprising the following steps: mixing and stirring a photocurable resin matrix, nano-reinforcing filler and photoinitiator, then adding modified solid epoxy resin foam balls, and ultrasonically dispersing to obtain a photocurable composite material for 3D printing lightweight structures.

[0085] In this invention, there are no special restrictions on the source of any raw materials; commercially available materials are acceptable. The types and amounts of the light-curing resin matrix, nano-reinforced filler, photoinitiator, and modified solid epoxy resin foam balls are the same as described above and will not be repeated here.

[0086] The photocurable resin matrix, nano-reinforcing filler, and photoinitiator are mixed and stirred. The stirring speed is preferably 1000-2000 r / min; optionally, the stirring speed is 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min, 2000 r / min, or any two of the above values. The stirring time is preferably 10-30 min; optionally, the stirring time is 10 min, 15 min, 20 min, 25 min, 30 min, or any two of the above values.

[0087] Then, modified solid epoxy resin foam balls are added and ultrasonically dispersed to obtain a photocurable composite material for 3D printing lightweight structures. The ultrasonic dispersion power is preferably 10~100 kHz; optionally, the ultrasonic dispersion power is 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz or any two of the above values; the ultrasonic dispersion time is preferably 5~30 min; optionally, the mixing and stirring time is 5 min, 10 min, 15 min, 20 min, 25 min, 30 min or any two of the above values.

[0088] The present invention also provides a 3D printed product, which is obtained by printing and curing the above-mentioned photopolymer composite material for 3D printing lightweight structures.

[0089] In one specific embodiment of the present invention, the printing process employs a photopolymerization printer, specifically a DLP or LCD photopolymerization printer.

[0090] In a specific embodiment of the present invention, the layer thickness of the printed layer is preferably 50~100 μm; optionally, the layer thickness of the printed layer is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any two of the above values; the exposure time of the printed layer is preferably 5~15 s / layer; optionally, the exposure time of the printed layer is 5 s / layer, 6 s / layer, 7 s / layer, 8 s / layer, 9 s / layer, 10 s / layer, 11 s / layer, 12 s / layer, 13 s / layer, 14 s / layer, 15 s / layer or any two of the above values.

[0091] In a specific embodiment of the present invention, the curing method is preferably heating; the curing temperature is preferably 60℃~100℃; optionally, the curing temperature is 60℃, 70℃, 80℃, 90℃, 100℃ or any two of the above values; the curing time is preferably 1~3 h; optionally, the curing time is 1 h, 1.5 h, 2 h, 2.5 h, 3 h or any two of the above values.

[0092] In one specific embodiment of the present invention, the bending strength of the 3D printed product is preferably 45~52 MPa; optionally, the bending strength of the 3D printed product is 45 MPa, 46 MPa, 47 MPa, 48 MPa, 49 MPa, 50 MPa, 51 MPa, 52 MPa or any two of the above values.

[0093] In one specific embodiment of the present invention, the interlayer bonding force of the 3D printed product is preferably 1.2~1.5 MPa; optionally, the interlayer bonding force of the 3D printed product is 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa or any two of the above values.

[0094] The 3D printing products provided by this invention can be applied to fields requiring high specific strength structures, such as aerospace, automotive lightweighting, and medical implants.

[0095] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a photocurable composite material for 3D printing lightweight structures, its preparation method, and the 3D printed product provided by the present invention.

[0096] All reagents used in the following examples are commercially available.

[0097] Example 1

[0098] 1.1 Preparation of solid epoxy resin foam balls:

[0099] 1) Preparation of resin compound: Bisphenol A type epoxy resin with an epoxy value of 0.50 mol / 100 g and a density of 1.15 g / cm³ was used. 3 Diaminodiphenylmethane and isophorone diamine with a density of 0.91 g / cm³ were mixed in a mass ratio of 10:2:1. The mixture was placed in a constant temperature oven preheated to 25°C and stirred for 10 min at 2000 r / min using a high-speed mixer to completely dissolve the curing agent into the epoxy resin, thus obtaining the epoxy resin compound.

[0100] 2) Liquid mixing: Add 2% by weight of EVA (ethylene-vinyl acetate copolymer, with a molecular weight of 150,000 g / mol) to the epoxy resin compound. l The toughening agent (VA content 12% by mass) and the diluent diethylene glycol monovinyl ether (10% by mass of the adhesive) were mixed in a high-speed mixer at 1800 r / min for 5 min to completely dissolve the epoxy curing agent mixture into the toughening agent and diluent, resulting in a liquid mixture.

[0101] 3) Powder mixing: Short-cut fibers with a diameter of 10 μm and a length of 5 mm are mixed with particles with a diameter of 50 μm and a density of 0.25 g / cm³. 3 Hollow glass microspheres were weighed at a mass ratio of 9:1 and then placed in a high-speed mixer and mixed at 2500 r / min for 30 min to obtain a powder mixture.

[0102] 4) Preparation of solid epoxy resin foam balls:

[0103] Place the polystyrene foam balls into a coating machine and control the rotation speed at 30 r / min. Place the liquid mixture prepared in step 2) into a mist spray gun and spray the solid polystyrene foam balls for 5 min at a flow rate of 160 mL / min. After spraying, use a high-pressure powder sprayer containing the powder mixture prepared in step 3) to continue spraying the solid polystyrene foam balls for 7 min at a flow rate of 400 g / min. Repeat this process 30 times, and then spray the outermost layer with the liquid mixture prepared in step 2 (flow rate 160 mL / min, spraying time 5 min).

[0104] After every 10 powder coating operations, a vacuum treatment with a negative pressure of 0.1 MPa is performed for 20 minutes.

[0105] Finally, heating at 80℃ for 5 hours was used to ensure complete curing of the material, resulting in solid epoxy resin foam balls.

[0106] 1.2 Modification of solid epoxy resin foam balls:

[0107] The solid epoxy resin foam balls prepared in 1.1 were placed in a plasma treatment device, and an argon / oxygen mixed gas (volume ratio 4:1) was introduced and treated with a power of 120 W for 8 min. They were then immersed in an ethanol solution containing 1% silane coupling agent KH560 for 30 min and dried at 60℃ to obtain modified solid epoxy resin foam balls.

[0108] 1.3 Preparation of photocurable composite materials:

[0109] 80 parts by weight of hexafunctional polyurethane acrylate R2601, 10 parts by weight of KH560 modified nano-silica with a particle size of 40 nm, and 3 parts by weight of TPO photoinitiator were stirred at 1500 r / min for 20 min; 150 parts by weight of modified solid epoxy resin foam balls (particle size 1 mm) were added, and the mixture was ultrasonically dispersed (40 kHz, 10 min) to form a uniform slurry, thus obtaining a photocurable composite material; wherein the KH560 modified nano-silica was obtained by immersing nano-silica in an ethanol solution containing 1% KH560 silane coupling agent for 30 min and drying at 60℃.

[0110] 1.4 3D Printing:

[0111] A DLP photopolymerization printer was used, with a layer thickness of 70 μm and a total thickness of 800 μm. The exposure time was 8 s / layer. After printing, the product was cured at 80℃ for 2 h to obtain the 3D printed product.

[0112] Example 2

[0113] The preparation method is the same as in Example 1, except that:

[0114] raw material:

[0115] 1. Modified solid epoxy resin foam balls (1 mm particle size, 150 parts).

[0116] 2. Hexafunctional polyurethane acrylate R2601 (80 parts);

[0117] 3. Nano SiO2 (5 parts, KH-560 modified);

[0118] 4. TPO photoinitiator (3 parts).

[0119] Process parameters:

[0120] 1. Plasma treatment power 120W, time 8min;

[0121] 2. Printed layer thickness: 50 μm; Total thickness: 800 μm;

[0122] 3. Exposure time: 5 seconds per layer;

[0123] 4. Curing conditions after printing: 80℃ for 2 hours.

[0124] Example 3

[0125] The preparation method is the same as in Example 1, except that:

[0126] raw material:

[0127] 1. Modified epoxy resin foam balls (1 mm particle size, 150 parts).

[0128] 2. Hexafunctional polyurethane acrylate R2601 (80 parts);

[0129] 3. Nano SiO2 (15 parts, KH-560 modified);

[0130] 4. TPO photoinitiator (3 parts).

[0131] Process parameters:

[0132] 1. Plasma treatment power 120W, time 8min;

[0133] 2. Printed layer thickness 100 μm; total thickness 800 μm;

[0134] 3. Exposure time: 15 seconds per layer;

[0135] 4. Curing conditions after printing: 80℃ for 2 hours.

[0136] Comparative Example 1

[0137] Compared to Example 1, the difference is that the solid epoxy resin foam balls are not subjected to plasma and silane modification treatment.

[0138] Comparative Example 2

[0139] Compared with Example 1, the difference is that the modified solid epoxy resin foam balls are replaced with an equal amount of hollow glass microspheres, with the same particle size and density as in Example 1.

[0140] Comparative Example 3

[0141] The difference from Example 1 is that modified solid epoxy foam balls with a particle size of 2.5 mm were used (modified solid epoxy foam balls with a particle size of 2.5 mm were prepared according to the method in Example 1, except that the number of coating layers was increased to obtain modified solid epoxy foam balls with a particle size of 2.5 mm).

[0142] Comparative Example 4

[0143] The difference compared to Example 1 is that the amount of nano-SiO2 used is reduced to 3 parts by weight.

[0144] Analysis: Insufficient nanofillers lead to increased resin shrinkage and decreased dimensional stability.

[0145] Comparative Example 5

[0146] The difference compared to Example 1 is that the printing is cured at 120°C. 。

[0147] Comparative Example 6

[0148] The difference from Example 1 is that the modified solid epoxy foam balls were replaced with the control sample: a commercially available light-cured lightweight material (brand: Formlabs Rigid 10K, containing hollow ceramic microspheres).

[0149] Comparative Example 7

[0150] The difference from Example 1 is that the nano-SiO2 was not modified with KH-560.

[0151] Comparative Example 8

[0152] The difference from Example 1 is that the modified solid epoxy resin foam balls were replaced with an equal amount (150 parts) of polystyrene foam balls with a particle size of 0.2 mm.

[0153] The performance of the photocurable composite materials and 3D printed products obtained in Examples 1-3 and Comparative Examples 1-8 was analyzed, and the results are shown in Table 1. The testing standards or methods are shown in Table 2.

[0154] Table 1 Performance test results of photopolymer composite materials and 3D printed products

[0155]

[0156] Table 2 Testing Standards or Methods

[0157]

[0158] The results of Example 1 and Comparative Example 1 show that modifying the solid epoxy resin foam balls increases the interlayer bonding strength by 133% and the printing success rate by 31%. In Comparative Example 1, the balls settled and the slurry separated during the printing process.

[0159] The results of Example 1, Comparative Example 2, and Comparative Example 3 show that the flexural strength of the modified solid epoxy resin foam balls used in Example 1 is 128% higher than that of the hollow glass microspheres. Due to the poor leveling properties of the slurry caused by the excessively large particle size, the interlayer bonding is weakened. Therefore, the flexural strength of Example 1 is 24% higher than that of Comparative Example 3.

[0160] The results of Example 1 and Comparative Example 4 show that when the amount of nano-SiO2 is less than 5 parts by weight, the strength decreases by 24%.

[0161] The results of Example 1 and Comparative Example 5 show that a suitable curing temperature helps to improve the degree of curing. In Comparative Example 5, single thermosetting cannot fully trigger the deep photoinitiator, and the crosslinking network is incomplete.

[0162] In summary, the 3D printed parts provided by this invention have the following advantages:

[0163] 1) Combining lightweight and high strength: The density is 0.65~0.75g / cm³, which is more than 30% lower than that of traditional light-cured resins (>1.1g / cm³); the flexural strength reaches 45.0~55.0 MPa, which is more than 70% higher than that of commercially available lightweight materials (such as hollow microsphere reinforced systems).

[0164] 2) Enhanced interfacial bonding: Plasma grafting and silane coupling agent modification increase the interlayer bonding force between the solid epoxy resin foam balls and the resin to 1.10~1.50MPa (unmodified only 0.58MPa); the foam balls and resin form an interlocking structure, avoiding interfacial delamination.

[0165] 3) Composite materials are suitable for large-span lightweight structures (such as drone wings), reducing weight by more than 30%.

[0166] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photopolymer composite material for 3D printing lightweight structures, characterized in that, include: 100-200 parts by weight of modified solid epoxy resin foam balls; 50-100 parts by weight of UV-curable resin matrix; 5-15 parts by weight of nano-reinforced filler; 1-5 parts by weight of photoinitiator; The modified solid epoxy resin foam ball is obtained by modifying solid epoxy resin foam balls; the modification process includes plasma treatment and silane coupling agent modification. The solid epoxy resin foam ball includes a core and a covering layer surrounding the core; the core is a foam ball; the covering layer includes a composite layer and an epoxy resin protective layer; the composite layer includes alternating epoxy resin layers and powder layers; the epoxy resin layers in the composite layer are in contact with the foam ball; the epoxy resin protective layer is disposed on the surface of the composite layer away from the foam ball; the powder layer includes chopped fibers and hollow glass microspheres. The viscosity of the photocurable resin matrix at 25°C is 200~700 cP.

2. The photocurable composite material according to claim 1, characterized in that, The epoxy resin layer and epoxy resin protective layer in the composite layer each independently include cured epoxy resin adhesive. The epoxy resin compound comprises bisphenol A epoxy resin and an amine curing agent; The mass ratio of the bisphenol A epoxy resin to the amine curing agent is 10:(1~5). And / or, the mass ratio of the chopped fibers to the hollow glass microspheres is (5~15):1; And / or, the diameter of the chopped fibers is 9~13 μm and the length of the chopped fibers is 3~10 mm; The hollow glass microspheres have a particle size of 10~50 μm and a density of 0.2~0.3 g / cm³. 3 .

3. The photocurable composite material according to claim 2, characterized in that, The bisphenol A type epoxy resin has an epoxy value of 0.48~0.54 mol / 100 g; And / or, the amine curing agent is selected from diaminodiphenylmethane and isophorone diamine; the mass ratio of diaminodiphenylmethane to isophorone diamine is (1~3):1; And / or the type of chopped fiber is glass fiber.

4. The photocurable composite material according to claim 1, characterized in that, The porosity of the solid epoxy resin foam balls is less than 1%; And / or, the density of the solid epoxy resin foam balls is 0.25~0.35 g / cm³. 3 ; And / or, the particle size of the solid epoxy resin foam balls is 0.5~2 mm; And / or, the particle size of the nano-reinforced filler is 20~50 nm; And / or, the photocurable resin matrix is ​​selected from acrylate resins; the functionality of the acrylate resin is 2 to 8.

5. The photocurable composite material according to claim 4, characterized in that, The photocurable resin matrix is ​​selected from polyurethane acrylate and / or epoxy acrylate; And / or, the nano-reinforcing filler is selected from one or more of nano-silica, carbon nanotubes, nano-silica treated with silane coupling agent and carbon nanotubes treated with silane coupling agent; And / or, the photoinitiator is selected from acylphosphine oxide photoinitiators.

6. The photocurable composite material according to claim 1, characterized in that, The gas used for plasma treatment is a mixture of argon and oxygen; the volume ratio of argon to oxygen is (2~6):

1. The power of the plasma treatment is 50~200 W; The plasma treatment time is 5-20 minutes; The silane coupling agent used for the silane coupling agent modification is selected from aminosilane coupling agents.

7. A method for preparing a photocurable composite material for 3D printing lightweight structures as described in claim 1, characterized in that, Includes the following steps: The photocurable resin matrix, nano-reinforcing filler and photoinitiator are mixed and stirred, then modified solid epoxy resin foam balls are added and ultrasonically dispersed to obtain a photocurable composite material for 3D printing lightweight structures.

8. The preparation method according to claim 7, characterized in that, The mixing and stirring speed is 1000~2000 r / min; The mixing and stirring time is 10~30 min; The power of the ultrasonic dispersion is 10~100 kHz; The ultrasonic dispersion time is 5~30 min.

9. A 3D printed product, characterized in that, The photocurable composite material for 3D printing lightweight structures prepared by any one of claims 1 to 6 or by the preparation method of claim 7 or 8 is obtained by printing and curing.

10. The 3D printed product according to claim 9, characterized in that, The thickness of the printed layer is 50~100 μm, and the exposure time is 5~15 s / layer; The curing temperature is 60~100℃; the curing time is 1~3 h.

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