A high photosensitive activity slurry for pure copper light-cured 3D printing and a preparation method thereof

Abstract

A kind of high photosensitivity slurry of pure copper photocuring 3D printing and preparation method thereof.The high photosensitivity slurry of pure copper photocuring 3D printing composition includes pure copper powder, active diluent, photoinitiator and auxiliary agent.The active diluent is acrylate monomer, and the photoinitiator includes two groups, one group is cleavage type alpha-amino ketone and its derivative, and the other group is thioxanthone and its derivative group.The thioxanthone photoinitiator has higher molar extinction coefficient in the ultraviolet light around 360nm-405nm wavelength, can compete with copper powder for ultraviolet light to avoid the high light absorption coefficient of copper powder to reduce the light initiation efficiency.At the same time, after thioxanthone absorbs ultraviolet light, energy transfer occurs with alpha-amino ketone, so that alpha-amino ketone photoinitiator jumps to excited triplet state, indirectly realizes slurry photopolymerization, greatly improves the light initiation efficiency, improves the photosensitivity of slurry, and solves the problem of high ultraviolet absorbance of copper powder.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of 3D printing slurry, in particular to a high photosensitivity slurry for pure copper photopolymerization 3D printing and a preparation method thereof. BACKGROUND

[0002] As an important metal material, copper has been paid more and more attention in recent years with the rapid development of electronic components and semiconductor industry. Copper has excellent electrical conductivity, oxidation resistance and corrosion resistance, and plays a crucial role in the manufacture of PCB, microprocessor, chip interconnection structure and the like. Meanwhile, copper can also be used for the manufacture of high power density radio frequency (RF) modules, which can provide low loss and high efficiency. However, for some precision machining design requirements of high parts, such as complex curved surface devices, the traditional forming and machining technology is difficult to meet the relevant technical requirements, which limits the further development and application of copper materials in various fields.

[0003] In recent years, photopolymerization 3D printing technology has been widely used in the ceramic market, and there are currently successful cases of industrial production of aluminum oxide, zirconium oxide and the like. Based on this, by using a slurry mixed by metal powder, photoinitiator, dispersant and photosensitive resin, it is possible to produce pure copper high-precision complex structure. The technology is a manufacturing technology that focuses light energy on a specific area to quickly harden or gel the material in the specific area, and can quickly adjust the parameters through numerical control program to print the best parts; and then through sintering and other processing methods, the green body is sintered into a solid copper component and the surface quality is improved. Compared with the stereolithography (SLA) scheme, the digital light processing (DLP) technology exposes and cures the UV light projection surface, which can improve the working efficiency while ensuring the printing precision. Therefore, it performs well in large-scale and complex tasks.

[0004] However, the pure copper powder has an ultraviolet light absorption rate of more than 90% in the wavelength range (365nm-405nm) of most industrial DLP printing equipment on the market, which makes the ultraviolet light absorption too high and difficult to achieve photopolymerization. For example, the preparation method of the photopolymerization copper electronic slurry disclosed in patent No. CN201510066529.8, the photopolymerization copper electronic slurry is cured in the ultraviolet light by a mercury lamp in a screen printing manner, and the irradiation time is as high as 40-100s. Although the copper slurry preliminarily realizes the photopolymerization behavior of copper, the pure copper powder has a very high absorption rate of ultraviolet light of the photopolymerization equipment, which reduces the activity of the photosensitive slurry. Therefore, to use the photopolymerization 3D printing method to realize the efficient production of complex structures of pure copper, it is necessary to improve the activity of the photosensitive slurry to improve the printing quality. SUMMARY

[0005] Therefore, the present application provides a high photosensitive activity slurry for pure copper light-cured 3D printing and a preparation method thereof to solve the above technical problems.

[0006] The high photosensitive activity slurry for pure copper light-cured 3D printing comprises pure copper powder, active diluent, photoinitiator and additive. The content of the pure copper powder is 87% to 92% by weight, the content of the active diluent is 5.6% to 9.4% by weight, the content of the additive is 2.6% to 2.8% by weight, and the content of the photoinitiator is 0.31% to 0.54% by weight. The active diluent is an acrylate monomer, and the photoinitiator includes two groups, one of which is a cleavage-type free radical photoinitiator, and the other is a hydrogen abstraction-type free radical photoinitiator.

[0007] Further, the pure copper powder is spherical or quasi-spherical copper powder, the particle size of the pure copper powder is 1-15 μm, and the median particle size is 1.84 μm.

[0008] Further, the active diluent is an acrylate monomer, and specifically includes one or more of dipropylene glycol diacrylate, cyclic trimethylolpropane formal acrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, and tripropylene glycol trimethacrylate.

[0009] Further, the additive is one or more of a metal powder surface modifier, a dispersant and an anti-settling agent.

[0010] A preparation method of the high photosensitive activity slurry for pure copper light-cured 3D printing, which comprises the following steps:

[0011] Step S1: a certain amount of active diluent is weighed according to a mass percentage of 5.6% to 9.4%, the active diluent is an acrylate monomer, a certain amount of additive is weighed according to a mass percentage of 2.6% to 2.8%, a certain amount of copper powder is weighed according to a mass percentage of 87% to 92%, and a certain amount of photoinitiator is weighed according to a mass percentage of 0.31% to 0.54%, the photoinitiator includes two groups, one of which is a cleavage-type free radical photoinitiator, and the other is a hydrogen abstraction-type free radical photoinitiator;

[0012] Step S2: the weighed active diluent, additive and photoinitiator are put into a high-speed disperser, and are dispersed at a speed of 1000-2000 r / min at 20-45°C for 3-10 min to make them fully mixed and dissolved, so as to obtain an organic carrier of the slurry;

[0013] Step S3: Pour the organic carrier into the stirring ball mill, and add the weighed copper powder in a small amount and multiple times, stir for 1-2 h at a speed of 100-450 r / min to fully mix;

[0014] Step S4: Put the mixed copper slurry into a vacuum defoaming machine, and vacuum defoam at room temperature to obtain the finished copper slurry.

[0015] Further, the collected three-dimensional ceramic material printing component model file such as abc, glTF, fbx, obj, dae, stl, 3ds, ply, etc. is converted into an stl file and imported into the printing system.

[0016] Further, in the above step S3, the ceramic printer equipped with an integrated slicing and printing system loads the STL file of the pretreated model, uses the slicing function, and outputs the two-dimensional slice PNG format image of the printing model.

[0017] Further, in the above step S4, the high-magnification rendering processing is four times or eight times, and the linearly connected region is defined as four-connected or eight-connected.

[0018] Further, in the above step S6, the parameters of the printer are as follows: LED light source wavelength 406 nm, printing layer thickness 0.03-0.1 mm, light intensity 10-200 mW / cm2, low exposure number 0-9999, low exposure time 1-60 s, and the remaining layer exposure time 1-60 s; the waiting time after each layer exposure is 1-300 s.

[0019] Compared with the prior art, the high photosensitive activity slurry for pure copper photocuring 3D printing provided by the application selects one or more of lower viscosity dipropylene glycol diacrylate, cyclic trimethylolpropane formal acrylate and other acrylate monomer active diluents, and is compounded with an auxiliary agent to obtain a low-viscosity copper powder slurry. The light initiator system is compounded by using alpha-amino ketone and its derivatives and thioxanthone and its derivatives, which effectively improves the light polymerization activity of the slurry. The thioxanthone light initiator has a relatively high molar extinction coefficient in ultraviolet light around 360 nm to 405 nm, can compete with copper powder for ultraviolet light to avoid the high light absorption coefficient of copper powder from causing a decrease in light initiation efficiency. At the same time, after absorbing ultraviolet light, the thioxanthone undergoes energy transfer with the alpha-amino ketone to make the alpha-amino ketone light initiator transition to an excited triplet state, thereby indirectly realizing light polymerization of the slurry. For ultraviolet light of a shorter wavelength, the compound of the two initiators can effectively broaden the wavelength range of available light. In addition, due to the presence of a tertiary amine structure in the alpha-amino ketone, on the one hand, the tertiary amine structure can form an aminoalkyl radical with high activity through a complex photochemical reaction with the thioxanthone light initiator, and on the other hand, the tertiary amine structure can eliminate the adverse effects of oxygen on polymerization through an oxidation-reduction reaction, thereby further improving the curing efficiency. Under the dual effects, the light initiation efficiency of the pure copper photosensitive slurry is greatly improved, the light sensitivity of the slurry is improved while ensuring a high solid content of the copper slurry, and the problem of high ultraviolet absorbance of copper powder is solved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The flow chart of the preparation method of the high photosensitive activity slurry for pure copper photocuring 3D printing provided by the application is shown in the figure. DETAILED DESCRIPTION

[0021] The specific embodiments of the application are further described below. It should be understood that the description of the embodiments of the application herein is not intended to limit the protection scope of the application.

[0022] A high photosensitive activity slurry for pure copper photocuring 3D printing, which comprises pure copper powder, an active diluent, a light initiator and an auxiliary agent. The weight percentage content of the pure copper powder is 87% to 92%, the weight percentage content of the active diluent is 5.6% to 9.4%, the weight percentage content of the auxiliary agent is 2.6% to 2.8%, and the weight percentage content of the light initiator is 0.31% to 0.54%.

[0023] The pure copper powder is spherical or spherical copper powder, the particle size of the pure copper powder is 1-15 μm, and the median particle size is 1.84 μm.

[0024] The active diluent is an acrylate monomer, specifically including one or more of dipropylene glycol diacrylate, cyclic trimethylolpropane formal acrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate, and tripropylene glycol trimethacrylate.

[0025] The photoinitiator includes two groups in total: one group is a cleavage-type free radical photoinitiator, and the selected one is a cleavage-type α-amino ketone and its derivatives, including one or more of 2-phenyl benzyl-2-dimethylamine-1-(4-morpholinyl benzyl) butanone, 2-dimethylamino-2-(4-methyl) benzyl-1-[4-(4-morpholinyl) phenyl]-1-butanone, 2-dimethylamino-2-benzyl-1-(4-piperidyl phenyl)-1-butanone, and 2-methyl-1-(4-methylthio phenyl)-2-morpholine-1-propanone. The other group is a hydrogen abstraction-type free radical photoinitiator, and the selected one is a thioxanthone and its derivatives, including one or more of 2-chlorothioxanthone (CTX), 2-isopropylthioxanthone (ITX), and 2,4-diethylthioxanthone (DETX).

[0026] The auxiliary agent is one or more of a metal powder surface modifier, a dispersant, and an anti-settling agent.

[0027] Example 1

[0028] Take 2.5% by mass of trimethylolpropane trimethacrylate, 3.3% of dipropylene glycol diacrylate, 2.5% of isobornyl methacrylate, 2.7% of a dispersant, 88.6% of copper powder, 0.2% of 2-phenyl benzyl-2-dimethylamine-1-(4-morpholinyl benzyl) butanone, and 0.2% of 2-chlorothioxanthone (CTX), and mix uniformly to prepare a photosensitive copper paste.

[0029] The prepared DLP printing copper paste has a viscosity of 1030 mPa·s, and is cured under a light source with a wavelength of 385 nm. When the exposure power is 230 mW / cm2, the film curing time is 20 s, and the cured layer thickness is 60 μm.

[0030] Example 2

[0031] Take 1.9% by mass of trimethylolpropane trimethacrylate, 2.6% of cyclic trimethylolpropane formal acrylate, 1.9% of tripropylene glycol trimethacrylate, 2.75% of a dispersant, 90.53% of copper powder, 0.16% of 2-dimethylamino-2-(4-methyl) benzyl-1-[4-(4-morpholinyl) phenyl]-1-butanone, and 0.16% of 2-isopropylthioxanthone, and mix uniformly to prepare a photosensitive copper paste.

[0032] The prepared DLP printing copper powder slurry has a viscosity of 5890 mPa·s, is cured under a light source with a wavelength of 385 nm, and has a film curing time of 35 s and a curing layer thickness of 60 μm when the exposure power is 230 mW / cm2.

[0033] The application also provides a preparation method of a high photosensitivity activity slurry for pure copper photocuring 3D printing, comprising the following steps:

[0034] Step S1: a certain amount of active diluent is weighed according to a mass percentage of 5.6% to 9.4%, the active diluent is an acrylate monomer, a certain amount of auxiliary agent is weighed according to a mass percentage of 2.6% to 2.8%, a certain amount of copper powder is weighed according to a mass percentage content of 87% to 92%, and a certain amount of photoinitiator is weighed according to a mass percentage of 0.31% to 0.54%. The photoinitiator includes two groups in total, one group is a cleavage type free radical photoinitiator, and an alpha-amino ketone and its derivatives are selected, and the other group is a hydrogen abstraction type free radical photoinitiator, and a thioxanthone and its derivatives are selected.

[0035] Step S2: the weighed active diluent, auxiliary agent and photoinitiator are put into a high-speed disperser, and are dispersed at a speed of 1000-2000 r / min at 20-45°C for 3-10 min to make them fully mixed and dissolved, so as to obtain an organic carrier of the slurry.

[0036] Step S3: the organic carrier is poured into a stirring ball mill, and the weighed copper powder is added in a small amount and multiple times, and is stirred at a speed of 100-450 r / min for 1-2 h to make it fully mixed.

[0037] Step S4: the mixed copper slurry is put into a vacuum defoaming machine, and is vacuum defoamed at room temperature to obtain a finished copper slurry product.

[0038] In the above step S1, the ratio of the two photoinitiators is 1:1, and the content of the photoinitiator and the auxiliary agent is 3wt% of the active diluent.

[0039] Compared with the prior art, the high photosensitivity slurry for pure copper photocuring 3D printing provided by the application selects one or more of the lower viscosity dipropylene glycol diacrylate, cyclic trimethylolpropane formal acrylate and other acrylate monomer active diluents, and is compounded with an auxiliary agent to obtain a low-viscosity copper powder slurry. The light initiator system is compounded by using alpha-amino ketone and its derivatives and thioxanthone and its derivatives, which effectively improves the photosensitivity of the slurry. The thioxanthone light initiator has a high molar extinction coefficient in the ultraviolet light around 360nm-405nm, and can compete with copper powder for ultraviolet light to avoid the high light absorption coefficient of copper powder leading to reduced light initiation efficiency. At the same time, after the thioxanthone absorbs ultraviolet light, energy transfer occurs with the alpha-amino ketone, which makes the alpha-amino ketone light initiator transition to the excited triplet state, and indirectly realizes the photosynthesis of the slurry. For shorter wavelength ultraviolet light, the compounding of the two initiators can effectively broaden the wavelength range of the available light. In addition, due to the presence of the tertiary amine structure in the alpha-amino ketone, on the one hand, it can form active aminoalkyl radicals through a complex photochemical reaction with the thioxanthone light initiator, and on the other hand, it can eliminate the adverse effects of oxygen on polymerization through an oxidation-reduction reaction, further improving the curing efficiency. Under the dual action, the light initiation efficiency of the pure copper photosensitive slurry is greatly improved, ensuring a high solid content of the copper slurry while improving the photosensitivity of the slurry, solving the problem of high ultraviolet absorbance of copper powder.

[0040] The above is only a preferred embodiment of the application, and is not used to limit the protection scope of the application, any modification, equivalent replacement or improvement within the spirit of the application, etc. are covered within the scope of the claims of the application.

Claims

1. A high photosensitivity paste for pure copper light-cured 3D printing, characterized in that: The pure copper light-cured 3D printing high photosensitive active paste composition comprises pure copper powder, active diluent, photoinitiator and auxiliary agent, the weight percentage content of the pure copper powder is 87%-92%, the weight percentage content of the active diluent is 5.6%-9.4%, the weight percentage content of the auxiliary agent is 2.6%-2.8%, and the weight percentage content of the photoinitiator is 0.31%-0.54%, the active diluent is an acrylate monomer, and the photoinitiator comprises two groups, one group is a cleavage type free radical photoinitiator, and the selected is a cleavage type α-amino ketone and its derivative, and the other group is a hydrogen abstraction type free radical photoinitiator, and the selected is a thioxanthone and its derivative, the ratio of the two groups of photoinitiators is 1:1, the active diluent is an acrylate monomer, and specifically comprises one or more of dipropylene glycol diacrylate, cyclic trimethylolpropane formal acrylate, isobornyl methacrylate, trimethylolpropane trimethacrylate and tripropylene glycol trimethacrylate.

2. The pure copper photo-curable 3D printed high photosensitivity active paste as claimed in claim 1, wherein: The pure copper powder is spherical or spherical copper powder, the particle size of the pure copper powder is 1-15 μm, and the median particle size is 1.84 μm.

3. The pure copper light-cured 3D printed high photosensitivity active paste as claimed in claim 1, wherein: The auxiliary agent is one or more of a metal powder surface modifier, a dispersant and an anti-settling agent.

4. A preparation method of the pure copper light-cured 3D printing high photosensitive active paste according to claim 1, comprising the following steps: Step S1: according to the mass percentage of 5.6%-9.4%, a certain amount of active diluent is weighed, the active diluent is an acrylate monomer, according to the mass percentage of 2.6%-2.8%, a certain amount of auxiliary agent is weighed, according to the mass percentage of 87%-92%, a certain amount of copper powder is weighed, and according to the mass percentage of 0.31%-0.54%, a certain amount of photoinitiator is weighed, the photoinitiator comprises two groups, one group is a cleavage type free radical photoinitiator, and the selected is a cleavage type α-amino ketone and its derivative, and the other group is a hydrogen abstraction type free radical photoinitiator, and the selected is a thioxanthone and its derivative; Step S2: the weighed active diluent, auxiliary agent and photoinitiator are put into a high-speed disperser, and are dispersed at a speed of 1000-2000 r / min at 20-45 °C for 3-10 min, so that they are fully mixed and dissolved, thereby obtaining an organic carrier of the paste; Step S3: the organic carrier is poured into a stirring ball mill, and the weighed copper powder is added in a small amount and multiple times, and is stirred at a speed of 100-450 r / min for 1-2 h, so that it is fully mixed; Step S4: the mixed copper paste is put into a vacuum defoaming machine, and is vacuum defoamed at room temperature to obtain the pure copper light-cured 3D printing high photosensitive active paste.

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