CN114437548B

CN114437548B - Moisture-heat dual-curing direct-writing type 3D printing medium, preparation method and application

Info

Publication number: CN114437548B
Application number: CN202210074097.5A
Authority: CN
Inventors: 朱晓艳; 李深; 严俊秋; 陈小朋
Original assignee: Corevoxel Hangzhou Technology Development Co ltd
Current assignee: Corevoxel Hangzhou Technology Development Co ltd
Priority date: 2022-01-21
Filing date: 2022-01-21
Publication date: 2022-12-27
Anticipated expiration: 2042-01-21
Also published as: CN114437548A

Abstract

The invention provides a moisture-heat dual-curing direct-writing 3D printing medium, a preparation method and application, wherein the curing mode of the direct-writing 3D printing medium is that moisture is pre-cured firstly, and then heating is carried out to carry out full curing, and the preparation method comprises the steps of mixing polysiloxane containing carbon double bonds, polysiloxane containing hydrogen, a tackifier, a platinum catalyst polymerization inhibitor and an inorganic nano filler to obtain a first mixture; heating the first mixture for a first time to obtain a second mixture; cooling the second mixture, and mixing the second mixture with a platinum catalyst to obtain a third mixture; under the inert gas atmosphere, adding polyether polyol and micromolecular polyol into a reactor, uniformly mixing, heating, carrying out vacuum defoaming, adding isocyanate and an isocyanate polymerization inhibitor, adding an isocyanate catalyst, and stirring to obtain a sixth mixture; and after being mixed, the third mixture and the sixth mixture are subjected to vacuum defoaming and pressure filtration in sequence, and the method is suitable for direct-writing 3D printing of line printing with the aspect ratio larger than 0.5.

Description

Moisture-heat dual-curing direct-writing type 3D printing medium, preparation method and application

Technical Field

The invention relates to the field of material preparation, in particular to a moisture-heat dual-curing direct-writing 3D printing medium, a preparation method and application.

Background

3D printing is used as a novel precision machining manufacturing technology, and is characterized in that the technology adopts a material increase manufacturing process from inexistence to inexistence in the manufacturing process, and a material decrease manufacturing process from inexistence to inexistence by gradually subtracting redundant materials is adopted in the traditional process. Compared with the traditional manufacturing process, the additive manufacturing 3D printing technology has higher flexibility and practicability. At present, the common 3D printing technologies include fused deposition ((FDM), stereo light curing (DLP, CLIP, or PolyJet), selective laser sintering (SLA, SLS), and three-dimensional printing (3 DP), however, these 3D printing technologies cannot use silica gel type dielectric materials to print precise structures.

Direct Ink Writing (DIW) is a new 3D printing technology, which is widely applied to the fields of electronic devices, structural materials, tissue engineering, soft robots and the like at present, and is capable of well fitting silica gel type dielectric materials to perform corresponding precision processing on products by extruding semisolid ink materials with shear thinning property from a printing nozzle and stacking the ink layers to construct a pre-designed three-dimensional structure.

In the prior art, technologies for researching silica gel printing media exist, for example, CN105643939B and CN107674429A disclose a 3D printing silica gel and a printing method thereof, respectively, however, a single-component silica gel material is adopted, and there is a risk that a storage period is short, and when printing is performed, a printing nozzle is easily blocked due to thickening, gel or coarse particles. CN106313505A and CN107638231A disclose a two-component mixed silica gel 3D printer and a printing method thereof, which do not disclose specific technical details of two-component mixed silica gel, and the temperature of the adopted annular heating plate is as high as 100-400 ℃ during printing, so that the high temperature easily causes the blockage of the printing nozzle due to the high-temperature gel of the silica gel inside. In addition, the common moisture-heat dual-curing composite materials on the market at present also have the problem of spray head blockage caused by rapid curing at the spray head.

In summary, no silica gel composite material which can be well adapted to direct-writing 3D printing exists in the market at present, and market popularization and application of the 3D printing technology are further limited.

Disclosure of Invention

The invention aims to provide a moisture-thermal dual-curing direct-writing 3D printing medium, a preparation method and application.

In order to achieve the above object, according to a first embodiment, the present disclosure provides a moisture-thermal dual-curing direct-writing 3D printing medium, where the viscosity of the direct-writing 3D printing medium is 200 to 1000Pa · s, the viscosity change value is less than or equal to 10% after being stored at room temperature for more than 30 days, the shore hardness after curing is more than 30A, and the curing method is pre-curing with moisture first, and then fully curing with heating.

Wherein the cone penetration at 25 ℃ is 120-280X 0.1mm.

Wherein the normal air humidity can be ensured to have good shape retention property when the normal air humidity is 50% or more, thereby ensuring that the leveling or collapse phenomenon can not occur under the condition of thermocuring.

Wherein the moisture-thermal dual-cured direct-write 3D printing medium is prepared by the following method: mixing polysiloxane containing carbon double bonds, hydrogen-containing polysiloxane, a tackifier, a platinum catalyst polymerization inhibitor and inorganic nano-filler to obtain a first mixture; heating the first mixture for a first time to obtain a second mixture; cooling the second mixture, and mixing the second mixture and a platinum catalyst to obtain a third mixture; adding polyether polyol and micromolecular polyol into a reactor under the atmosphere of inert gas, uniformly mixing, heating and defoaming in vacuum to obtain a fourth mixture; adding isocyanate and an isocyanate polymerization inhibitor into the fourth mixture, and stirring at a high speed and defoaming in vacuum to obtain a fifth mixture; adding an isocyanate catalyst into the fifth mixed material and stirring to obtain a sixth mixed material; and mixing the third mixture and the sixth mixture, and then sequentially performing vacuum defoaming and pressure filtration to obtain the direct-writing 3D printing medium.

In a second embodiment, the present scheme provides a method for preparing a moisture-thermal dual-cured direct-writing 3D printing medium, including the following steps:

s1, mixing polysiloxane containing carbon double bonds, hydrogen-containing polysiloxane, a tackifier, a platinum catalyst polymerization inhibitor and an inorganic nano filler to obtain a first mixture;

s2, heating the first mixture for a first time to obtain a second mixture;

s3, cooling the second mixture, and mixing the second mixture with a platinum catalyst to obtain a third mixture;

s4, adding polyether polyol and micromolecular polyol into a reactor in an inert gas atmosphere, uniformly mixing, heating and defoaming in vacuum to obtain a fourth mixture;

s5, adding isocyanate and an isocyanate polymerization inhibitor into the fourth mixture, and stirring at a high speed for vacuum defoaming to obtain a fifth mixture;

s6, adding an isocyanate catalyst into the fifth mixed material and stirring to obtain a sixth mixed material;

and S7, mixing the third mixture and the sixth mixture, and then sequentially performing vacuum defoaming and pressure filtration to obtain the direct-writing 3D printing medium.

In step S1, polysiloxane, hydrogen-containing polysiloxane, tackifier, platinum catalyst inhibitor, and inorganic nanofiller are mixed with each other.

In the mixing reaction, the polysiloxane, the hydrogenpolysiloxane and the adhesion promoter are used according to the following conditions: 100:20 to 100:10 to 50. In some embodiments, the ratio is preferably 100:20 to 80:20 to 40.

The polysiloxane containing carbon double bonds is at least one of vinyl polysiloxane, methyl vinyl polysiloxane and methyl phenyl vinyl polysiloxane. If the polysiloxane containing carbon double bonds is selected from vinyl polysiloxane, wherein vinyl in the vinyl polysiloxane is at alpha, omega or middle position of polysiloxane molecular chain, the viscosity of the vinyl polysiloxane is 50-500 Pa.s, the vinyl content is 0.05-l0 mol%, each molecule of the vinyl polysiloxane contains more than 2 vinyl functional groups connected with silicon atoms, and the molecular weight is (40-100) multiplied by 10 ⁴ 。

The tackifier is: HO-Si (CH) ₃ ) ₂ O[Si(CH ₃ ) ₂ O] _n Si(CH ₃ ) ₂ -OH, n = 3-8, one or more of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), mixed rings of Dimethylsiloxanes (DMC)。

The platinum catalyst polymerization inhibitor is alkynol with carbon number less than 15, preferably one or more of 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, propargyl alcohol, 3-butyn-1-ol and 3, 5-dimethyl-1-hexyn-3-ol, and the mass fraction of the inhibitor added into the medium material is 0.1-2%.

The hydrogenpolysiloxane is at least one of methyl hydrogenpolysiloxane, methyl phenyl hydrogenpolysiloxane, methyl hydrogenpolysiloxane and phenyl hydrogenpolysiloxane, wherein the viscosity of the hydrogenpolysiloxane is 50-500 Pa.s, and the hydrogen content is 0.1-1mol%; the hydrogen-containing polysiloxane contains more than 2 hydrogen atoms connected with silicon atoms in each molecule, and the molecular weight is (40-100) multiplied by 10 ⁴ 。

Wherein the inorganic nano-filler is one or more of silicon dioxide, calcium silicate, calcium carbonate, titanium dioxide, carbon black, graphene and zinc oxide, and the size of the inorganic nano-filler is 1-500 nm.

In step S2, the first mixture is heated to 50-80 ℃, and the first mixture is stabilized at any temperature of 50-80 ℃ for a first time period, so that the purpose of processing the first mixture is as follows: at higher temperatures, the material fluidity changes, and mixing can be more uniform and thorough, the first time period is 30-180 minutes, and can be 40/50/60/70/80/90/100/110min; the first mix was also stabilized at 60/70 ℃.

In addition, the first mix of step S2 is heated while being stirred at a high speed.

In step S3, the temperature of the second mix is reduced to less than 50 ℃. Platinum catalysts are highly catalytically active at higher temperatures, which leads to the curing of polysiloxanes by polymerization, and therefore it is necessary to introduce the catalyst at relatively low temperatures to prevent the material from already beginning to cure during the gum making process.

And the step adds platinum catalyst into the second mixture as corresponding catalyst for the thermal curing of the material. Without these materials, no curing will occur upon final heating.

The platinum catalyst used was: the chloroplatinic acid or the complex formed by the chloroplatinic acid and the alkene, the cycloalkane, the alcohol, the ester, the ketone and the ether is at least one, preferably a Speier platinum catalyst or a Karstedt platinum catalyst with the platinum metal content of 0.1-5%, and the mass fraction of the catalyst added into the medium material is 0.1-0.5%.

The mixing means provided by the scheme adopts one or more of ball milling, grinding or mechanical stirring, and the mixing materials can be uniformly mixed.

In step S4, the inert gas atmosphere may be a nitrogen atmosphere, and the inert gas atmosphere is selected to have the following advantages: ensuring that the curing is not carried out in the preparation process.

After being uniformly mixed, the polyether polyol and the micromolecular polyol can be heated to any temperature of 100-150 ℃, which can be 110/120/130/140 ℃, and the mixture of the polyether polyol and the micromolecular polyol is placed under high-speed stirring for vacuum defoamation for 1-5 hours to obtain a fourth mixture. The role of this step is: a small amount of water is contained in the alcohol, and the water in the mixing process is removed, so that the prepared material is prevented from being solidified due to the residual water in the system.

In the embodiment of the present embodiment, the polyether polyol functions as a solvent and the small molecule polyol functions as a reaction monomer.

In the embodiment of the present disclosure, the polyether polyol refers to a polyether polyol having a functionality of 2 and a hydroxyl value of 18 to 560mgKOH/g, and the number average molecular weight ranges from: 2000-6000.

Preferably, the polyether polyol is one or more of polyoxypropylene glycol, polyethylene glycol, polytetrahydrofuran ether glycol and tetrahydrofuran-propylene oxide copolymerized glycol.

The micromolecular polyalcohol is micromolecular alcohol with the carbon atom number of 2-10. Including but not limited to ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, pentanediol, neopentyl glycol, hexanediol, methyl propanediol, 1, 4-cyclohexanedimethanol, such small molecule alcohols may be used alone or in combination. Preferably, it is one or more of propylene glycol, butylene glycol, methyl propylene glycol and dipropylene glycol.

In step S5, the isocyanate and the isocyanate polymerization inhibitor are added to the fourth mixture, so that the isocyanate can be polymerized with alcohol and cured after contacting water, and the polymerization inhibitor is used to improve the stability of the material during storage and prevent complete curing once encountering a trace amount of water molecules. The isocyanate is used for polymerizing monomers in a polymerization reaction and isocyanate which can be polymerized with alcohol when meeting water, the isocyanate polymerization inhibitor is an acidic substance for providing active hydrogen and is used for inhibiting the activity of an isocyanate catalyst, so that the material has better stability in the storage process, and the ratio of the isocyanate to the isocyanate polymerization inhibitor is 100.1-10.

The isocyanate in the scheme is one or more of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), tetramethyldimethylene diisocyanate (TMXDI) and isophorone diisocyanate (IPDI).

The isocyanate polymerization inhibitor refers to an acidic substance that provides active hydrogen. Including but not limited to phosphoric acid, hypophosphorous acid, hydroquinone, erucic acid, benzoic acid, citric acid, and such polymerization inhibitors may be used alone or in combination. Preferably, the isocyanate polymerization inhibitor is benzoic acid.

In step S6, an isocyanate catalyst is added to the fifth mixed material and stirred to obtain a sixth mixed material, which has the functions of accelerating the polymerization reaction speed of the isocyanate after contacting water, and improving the polymerization degree of the reaction and the shape retention of the final material.

In the specific embodiment of the scheme, the isocyanate catalyst is added, and the mixture is stirred at a high speed for 30-120 min to obtain a sixth mixture.

The isocyanate catalyst includes, but is not limited to, titanates, organotin compounds, bismuth compounds, amines, and morpholine derivatives of organic ligands or complex ligands, and such catalysts may be used alone or in combination. Preferably, the isocyanate catalyst is dibutyltin dilaurate.

After the sixth mixture and the third mixture are obtained, the third mixture and the sixth mixture are uniformly mixed, one or more of ball milling, grinding or mechanical stirring is adopted in the mixing process, and then the composite material for direct-writing 3D printing is obtained by sequentially carrying out vacuum defoaming and pressure filtration. The benefits of this are: the reaction temperature for the preparation of the two is different, and the preparation of the two is only carried out in the air, and the other is carried out in the inert atmosphere.

In a third embodiment, the scheme provides an application of the direct-writing 3D printing medium prepared according to the preparation method, and the direct-writing 3D printing medium is applied to direct-writing 3D printing, wherein the printed line width is 1-200 μm, and the direct-writing 3D printing medium is suitable for line printing with the aspect ratio larger than 0.5.

Compared with the prior art, the technical scheme has the following characteristics and beneficial effects:

1. the viscosity attribute of the direct-writing 3D printing medium can be as high as 200-1000 Pa.s, the shape retention of a printed product is strong, the phenomenon of line collapse is not easy to occur in the curing process of the product, the high-precision printing of micron-level lines is further met, the printed line width is 1-200 mu m, and the direct-writing 3D printing medium is suitable for line printing with the aspect ratio larger than 0.5. And the condition that traditional medium material promotes material viscosity through the packing particle of packing micron size granule is different from, the compound printing medium of this scheme viscosity itself is higher, and then reduces the risk that the jam shower nozzle appears.

2. The direct-writing 3D printing medium has good long-time storage stability, can have a viscosity change value of less than or equal to 10 percent at room temperature for more than 30 days, has a cone penetration of 120-280 multiplied by 0.1mm at 25 ℃, has a change value of less than or equal to 10 percent at 30 days, can meet the long-time printing of 3D printing, and further ensures that the composite printing medium has high viscosity and high stability

3. According to the scheme, the moisture-heat dual-curing resin is introduced to the process of preparing the direct-writing 3D printing medium and serves as an auxiliary material of the silica gel material, the moisture in the air is used for curing the moisture-curing resin in the printing process, so that the corresponding tackifying effect is achieved, the shape keeping performance of the material is realized, the full curing of the composite material in the heating process is realized, the shape keeping performance of a printed graph is guaranteed, the viscosity and the storage stability of the material can be guaranteed, and meanwhile, the dual effects of moisture curing and high-temperature curing are combined. The Shore hardness after curing is above 30A.

Drawings

Fig. 1 is a schematic view of a print result corresponding to embodiment 1.

Fig. 2 is a three-dimensional structure diagram corresponding to the printing line width of embodiment 1.

Fig. 3 is a schematic view of a print result corresponding to embodiment 2.

Fig. 4 is a three-dimensional structural view of a print line width corresponding to embodiment 2.

Fig. 5 is a schematic view of a print result corresponding to embodiment 3.

Fig. 6 is a three-dimensional structure diagram corresponding to the print line width of embodiment 3.

Fig. 7 is a schematic view of the print result corresponding to the control group 1.

Fig. 8 is a three-dimensional structural view of the print line width corresponding to the control 1.

Fig. 9 is a schematic view of the print result corresponding to the control group 2.

Fig. 10 is a three-dimensional structural view of the print line width corresponding to the control group 2.

Fig. 11 is a schematic view of the print result corresponding to the control group 4.

Fig. 12 is a three-dimensional structural view of the print line width corresponding to the comparison group 4.

Fig. 13 is a schematic flow chart of a method for manufacturing a moisture-thermal dual-cured direct-writing 3D printing medium according to the present embodiment.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived from the embodiments of the present invention by a person skilled in the art, are within the scope of the present invention.

It is understood that the terms "a" and "an" should be interpreted as meaning "at least one" or "one or more," i.e., that a quantity of one element may be one in one embodiment, while a quantity of another element may be plural in other embodiments, and the terms "a" and "an" should not be interpreted as limiting the quantity.

The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. It is to be understood that the scope of the invention is not to be limited to the specific embodiments described below; it is also to be understood that the terminology used in the examples herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. The test methods in the following examples, in which specific conditions are not specified, are generally carried out according to conventional methods or according to conditions recommended by the respective manufacturers.

The first embodiment is as follows: preparation of direct-write 3D printing medium (viscosity 200Pa · s):

(1) 80g of a polymer having a viscosity of 50 pas, a vinyl content of 0.05mo1%, and a molecular weight of 40X 10 ⁴ 50g of a vinylpolysiloxane having a viscosity of 50 pas, a hydrogen content of 0.1mo1% and a molecular weight of 40X 10 ⁴ Hydrogen-containing polysiloxane, 20g of hexamethylcyclotrisiloxane (D3), 0.2g of 1-ethynyl-1-cyclohexanol and 20g of hydrophobic fumed silica with the particle size of 20-30 nm are added into a stirring kettle and evenly mixed,

(2) Heating to 70 ℃, reacting for 30min,

(3) Cooling to 30 deg.C, adding 0.2g Karstedt platinum catalyst, mixing, and stirring at room temperature for 2 hr;

(4) Putting 10g of polyoxypropylene glycol (average molecular weight 2000) and 10g of propylene glycol into a reaction kettle, heating to 100 ℃, and dehydrating for 1 hour under the vacuum degree of 0.1 MPa;

(5) Adding 10g of diphenylmethane diisocyanate (MDI) and 0.1g of benzoic acid, and reacting at 100 ℃ for 1 hour;

(6) Cooling to 50 ℃, adding 0.2g of dibutyltin dilaurate, and reacting for 30min at 50 ℃;

(7) And (4) uniformly mixing the silica gel material obtained in the step (1-3) with the polyurethane material obtained in the step (4-6), moving out to a three-roller machine, grinding to a size of less than 5 mu m, and finally performing pressure filtration to obtain the direct-writing 3D printing medium with the viscosity of 200Pa s.

And (3) performance testing:

the viscosity of the composite printing medium was measured by a viscometer and was 200Pa · s. The cone penetration was measured for 30 days using a cone penetration meter (25 ℃,0.1 mm) and was 282 (initial value) and 279 (after 30 days), respectively, and the material showed good storage stability.

Application test: as shown in fig. 1 and fig. 2, in this embodiment, a ceramic needle with an inner diameter of 10 μm is used, and a line width with a good aspect ratio can still be printed at a printing speed of 70mm/s, where the specific values are: the height is 7 μm, the width is 12 μm, and the hardness of the cured material is 39 by using a Shore A durometer.

Example two: preparation of composite 3D printing medium (viscosity 500Pa · s):

(1) 80g of a methylvinylpolysiloxane having a viscosity of 100 pas, a vinyl content of 5mo1% and a molecular weight of 70X 104, 50g of a methylvinylpolysiloxane having a viscosity of 100 pas, a hydrogen content of 0.5mo1% and a molecular weight of 70X 10 ⁴ Of hydrogenpolysiloxane, HO-Si (CH) ₃ ) ₂ O[Si(CH ₃ ) ₂ O] ₃ Si(CH ₃ ) ₂ 30g of-OH, 1g of propargyl alcohol and 20g to 100nm of titanium dioxide are added into a stirring kettle and mixed evenly;

(2) Heating to 80 ℃, and reacting for 100min;

(3) Cooling to 30 ℃, adding 0.5g Karstedt platinum catalyst, and stirring for 2 hours at normal temperature;

(4) Putting 20g of polyethylene glycol (average molecular weight 4000) and 10g of butanediol into a reaction kettle, heating to 120 ℃, and dehydrating for 2 hours under the vacuum degree of 0.1 MPa;

(5) Adding 20g of Toluene Diisocyanate (TDI) and 0.2g of phosphoric acid, and reacting for 2 hours at 120 ℃;

(6) Cooling to 50 ℃, adding 0.5g of N-methylmorpholine, and reacting for 60min at 50 ℃;

(7) And (4) uniformly mixing the silica gel material obtained in the step (1-3) with the polyurethane material obtained in the step (4-6), moving out to a three-roller machine, grinding to a size of less than 10 mu m, and finally performing pressure filtration to obtain the direct-writing 3D printing medium with the viscosity of 500Pa s.

And (3) performance testing:

the viscosity of the composite printing medium was measured by a viscometer, and the viscosity was 500Pa · s. The cone penetration was measured for 30 days using a cone penetration meter (25 ℃,0.1 mm) and was 178 (initial value) and 180 (after 30 days), respectively, and the material showed good storage stability.

Application test: as shown in fig. 3 and 4, the present embodiment uses a ceramic needle with an inner diameter of 50 μm, and can still print a line width with a good aspect ratio at a printing speed of 70mm/s, where the specific values are: the height is 40 μm, the width is 50 μm, and the hardness of the cured material is 52 by using a Shore A durometer.

Example three: preparation of composite 3D print media (viscosity 1000Pa · s):

(1) 80g of a polymer having a viscosity of 500 pas, a vinyl content of 10mo1%, and a molecular weight of 100X 10 ⁴ 40g of a methylphenylvinylpolysiloxane having a viscosity of 500 pas, a hydrogen content of 1mo1% and a molecular weight of 100X 10 ⁴ 20g of hydrogenpolysiloxane and dimethyl siloxane mixed ring body (DMC), 4g of 3-butyne-1-ol and 20g of 10-20 nm carbon black are added into a stirring kettle to be uniformly mixed,

(2) Heating to 80 ℃, and reacting for 180min;

(3) Cooling to 30 ℃, adding 1g of Karstedt platinum catalyst, and stirring for 2 hours at normal temperature;

(4) Putting 15g of polytetrahydrofuran ether glycol (average molecular weight is 6000) and 10g of methyl propylene glycol into a reaction kettle, heating to 150 ℃, and dehydrating for 5 hours under the vacuum degree of 0.1 MPa;

(5) Adding 15g of isophorone diisocyanate (IPDI) and 0.5g of citric acid, and reacting at 150 ℃ for 5 hours;

(6) Cooling to 50 ℃, adding 1g of triethylene diamine, and reacting for 120min at 50 ℃;

(7) And (4) uniformly mixing the silica gel material obtained in the step (1-3) with the polyurethane material obtained in the step (4-6), moving out to a three-roller machine, grinding to a size of less than 10 mu m, and finally performing pressure filtration to obtain the direct-writing 3D printing medium with the viscosity of 1000Pa s.

And (4) performance testing:

the viscosity of the composite printing medium was measured by a viscometer and was 1000Pa · s. The cone penetration was measured for 30 days using a cone penetration meter (25 ℃,0.1 mm) and was 112 (initial value) and 119 (value after 30 days), respectively, and the material showed good storage stability.

Application test: as shown in fig. 5 and fig. 6, the present embodiment uses a ceramic needle with an inner diameter of 100 μm, and can still print a line width with a good aspect ratio at a printing speed of 50mm/s, where the specific values are: the height is 90 μm, the width is 110 μm, and the hardness of the cured material is 80 by using a Shore A hardness tester.

Control group 1: the operation process is the same as that of example 1, the steps 4-6 are removed, and the single-component silica gel material is prepared:

(1) 80g of a polymer having a viscosity of 50 pas, a vinyl content of 0.05mo1%, and a molecular weight of 40X 10 ⁴ 50g of vinyl polysiloxane, 50 Pa.s of viscosity, 0.1mo1% of hydrogen content and 40 multiplied by 104 molecular weight hydrogen-containing polysiloxane, 20g of hexamethylcyclotrisiloxane (D3), 0.2g of 1-ethynyl-1-cyclohexanol and 20g of 20-30 nm hydrophobic gas phase silicon dioxide, adding into a stirring kettle, uniformly mixing,

(2) Heating to 70 ℃, reacting for 30min,

(4) And (3) moving the silica gel material obtained in the step (1-3) out to a three-roller machine, grinding the silica gel material to the size of less than 5 microns, and finally performing pressure filtration to obtain the direct-writing 3D printing medium with the viscosity of 200Pa s.

Final material properties:

material viscosity: 220 Pa.s, cone penetration of 30 days, determined using a cone penetration meter (25 ℃,0.1 mm), had values of 277 (initial value) and 282 (value after 30 days), respectively, and the material showed good storage stability. As shown in FIGS. 7 and 8, in the comparative example, the printing line shape retention was poor at a printing speed of 70mm/s using a ceramic tip having an inner diameter of 10 μm, and the specific values were: the height is 6 μm, the width is 15 μm, and the hardness of the cured material is 53 by using a Shore A durometer.

The comparison between the control 1 and the example 1 shows that: the aspect ratio is less than 0.5, and the introduction of the moisture curing material proves that the corresponding gain effect is achieved in the aspect of ensuring the aspect ratio of the printed lines.

Control group 2:

the isocyanate catalyst dibutyltin dilaurate of the step (6) was removed in the same operation as in example 1.

Final material properties:

material viscosity: 212 Pa.s, cone penetration for 30 days measured by a cone penetration meter (25 ℃,0.1 mm), 286 initial values, and 253 (value after 30 days), the hardness of the material gradually increased after standing for a long time, and the storage stability was poor. As shown in FIGS. 9 to 10, in the comparative example, the printing line shape retention was poor at a printing speed of 70mm/s using a ceramic tip having an inner diameter of 10 μm, and the specific values were: the height is 4 μm, the width is 12 μm, and the hardness of the cured material is 29 by a Shore A durometer test.

The comparison between the control group 2 and the example 1 shows that: curing cannot be realized without adding an isocyanate catalyst, and the structural stability is poor.

Control group 3:

the isocyanate polymerization inhibitor benzoic acid of step (3) was removed in the same manner as in example 1.

Final material properties:

material viscosity: 249 Pa.s, the cone penetration of 30 days is measured by a cone penetration meter (25 ℃,0.1 mm), the value is 236 (initial value), the hardness reaches 176 after 30min, and the storage stability of the material is poor. The hardness of the cured material was 47 using a shore a durometer.

Control group 4

The procedure of example 1 was followed to remove hexamethylcyclotrisiloxane (D3), which is an adhesion promoter in step (1).

Material viscosity: 100 Pa.s, 335 (initial value), 287 (value after 30 days) by cone penetration meter (25 deg.C, 0.1 mm), the material has gradually increased hardness and poor storage stability after standing for a long time. As shown in fig. 11 and 12, the present scheme adopts a ceramic needle with an inner diameter of 10 μm, and the printed linear shape retention is poor when the printing speed is 70mm/s, and the specific values are as follows: the height is 3 mu m, the width is 12 mu m, and the hardness of the cured material is 12 by adopting a Shore A durometer

Summary the performance tests of the direct-write 3D printing media of the above examples and control are as follows:

it can also be clearly seen from the table that the present solution provides the direct-write 3D printing media of examples 1 to 3 with good performance, and the preparation method provided by the present solution is particularly advantageous.

The present invention is not limited to the above preferred embodiments, and any other various products can be obtained by anyone in light of the present invention, but any changes in shape or structure thereof, which are similar or identical to the technical solution of the present invention, fall within the protection scope of the present invention.

Claims

1. A preparation method of a moisture-thermal dual-curing direct-writing type 3D printing medium is characterized by comprising the following steps:

s1, mixing polysiloxane containing carbon double bonds, hydrogen-containing polysiloxane, a tackifier, a platinum catalyst polymerization inhibitor and an inorganic nano filler to obtain a first mixture, wherein the platinum catalyst polymerization inhibitor is alkynol with carbon number less than 15;

s2, heating the first mixture for a first time period to obtain a second mixture, wherein the temperature of the first mixture is increased to 50-80 ℃, and the first time period is 30-180 minutes;

s3, cooling the second mixture, mixing the second mixture with a platinum catalyst to obtain a third mixture, and cooling the second mixture to below 50 ℃;

s5, adding isocyanate and an isocyanate polymerization inhibitor into the fourth mixture, stirring at a high speed, and performing vacuum defoaming to obtain a fifth mixture, wherein the isocyanate polymerization inhibitor is an acidic substance for providing active hydrogen;

s6, adding an isocyanate catalyst into the fifth mixture and stirring to obtain a sixth mixture;

and S7, mixing the third mixture and the sixth mixture, and then sequentially carrying out vacuum defoaming and pressure filtration to obtain the direct-writing 3D printing medium, wherein the isocyanate catalyst is selected from one or more of titanate of an organic ligand or a complex ligand, an organic tin compound, a bismuth compound, an amine substance and a morpholine derivative.

2. The method for producing a moisture-thermal dual-curable direct-write 3D printing medium according to claim 1, wherein the polysiloxane containing a carbon double bond is at least one of vinyl polysiloxane, methyl vinyl polysiloxane, and methyl phenyl vinyl polysiloxane.

3. The method for preparing a moisture-thermal dual-curing direct-writing 3D printing medium according to claim 1, wherein the hydrogenpolysiloxane is at least one of methyl hydrogenpolysiloxane, methylphenyl hydrogenpolysiloxane, methyl hydrogenpolysiloxane and phenyl hydrogenpolysiloxane.

4. The method for preparing a moisture-thermal dual-cured direct-writing type 3D printing medium according to claim 1, wherein the platinum catalyst is: chloroplatinic acid or at least one complex of chloroplatinic acid and alkene, cycloalkane, alcohol, ester, ketone and ether.

5. The method for preparing a wet-thermal dual-cured direct-write 3D printing medium according to claim 1, wherein the tackifier is: HO-Si (CH) ₃ ) ₂ O[Si(CH ₃ ) ₂ O] _n Si(CH ₃ ) ₂ -OH, n =3 to 8, hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dimethylsiloxane mixed ring bodies (DMC) or a combination thereof.

6. The method for preparing a moisture-thermal dual-cured direct-write 3D printing medium according to claim 1, wherein the polyether polyol is a polyether polyol having a functionality of 2 and a hydroxyl value of 18-560mg KOH/g.

7. The method for preparing a moisture-thermal dual-cured direct-write 3D printing medium according to claim 1, wherein the isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, tetramethyldimethylene diisocyanate, and isophorone diisocyanate.

8. The method for preparing a moisture-thermal dual-cured direct-write 3D printing medium according to claim 1, wherein the small molecular polyol is a small molecular alcohol having 2-10 carbon atoms.

9. The preparation method of the moisture-thermal dual-cured direct-writing 3D printing medium according to claim 1, wherein the inorganic nano-filler is one or more of silica, calcium silicate, calcium carbonate, titanium dioxide, carbon black, graphene and zinc oxide.

10. A moisture-thermal dual-cured direct-write 3D printing medium, characterized in that it is prepared by the method of preparing a moisture-thermal dual-cured direct-write 3D printing medium according to any one of claims 1 to 9.

11. The moisture-thermal dual-curing direct-writing 3D printing medium according to claim 10, wherein the viscosity of the direct-writing 3D printing medium is 200 to 1000 Pa-s, the viscosity change value is less than or equal to 10% after the medium is stored for more than 30 days at room temperature, the Shore hardness after curing is more than 30A, and the curing method comprises the steps of moisture pre-curing and heating for full curing.

12. Application of the direct-writing 3D printing medium is characterized in that the direct-writing 3D printing medium prepared from the wet-thermal dual-curing direct-writing 3D printing medium according to claim 10 is applied to direct-writing 3D printing, the printed line width is 1-200 μm, and the direct-writing 3D printing medium is suitable for line printing with the aspect ratio larger than 0.5.