Organosilicon-based 3D printing cushion material and preparation method thereof

Abstract

The invention relates to the technical field of organic silicon materials and 3D printing compounding, in particular to a 3D printing cushion material based on organic silicon and a preparation method of the 3D printing cushion material. The 3D printing cushion material based on organic silicon is obtained by extruding an organic silicon composition through a 3D printer to form a precursor with a hollow-out pattern, and curing the precursor under a heating condition. By designing a system formula, the maximum unsupported cantilever length in the printing process is remarkably increased. The excellent performance of the silica gel pad is guaranteed, the structural design freedom degree is expanded, supporting materials and post-processing steps are reduced, and finally a solution which is high in efficiency, low in cost and high in reliability is achieved.

Description

Technical Field

[0001] This invention relates to the field of organosilicon materials and 3D printing composite technology, specifically to an organosilicon-based 3D printing pad and its preparation method. Background Technology

[0002] 3D printed mat materials have a wide range of applications. 3D printed seat cushions combine the advantages of low density and customizable patterns, and are already being customized in products such as yoga mats and bicycle saddles. 3D printed mats allow for precise control of density, toughness, and hardness in different areas to meet diverse usage needs. For example, in bicycle saddles, the ischial tuberosities require stronger support, while other areas need greater flexibility to improve user comfort. Currently, most mainstream 3D printed mat materials are manufactured using molding processes with materials such as PVC, TPE, and natural rubber. However, these materials suffer from drawbacks such as inconsistent performance, inability to provide personalized support, and some materials being environmentally unfriendly.

[0003] 3D printing technology has made personalized manufacturing possible. However, applying 3D printing to products with large dimensions and high elasticity requirements, such as yoga mats and bicycle saddles, faces two major challenges:

[0004] 1. Support Structure Challenges: When printing overhanging structures using traditional fused deposition modeling (FDM) or stereolithography (SLA / DLP) techniques, additional support structures must be printed. These supports need to be removed later, which not only complicates the process and wastes materials but also leaves scars on the product surface, severely affecting the feel and appearance of the yoga mat.

[0005] 2. Material and process compatibility challenges: Ordinary silicone materials lack suitable rheological properties for printing and are prone to collapse and deformation after extrusion. Although unsupported technologies such as gel suspension printing have emerged recently, their equipment is complex and expensive, and they rely on special external media (such as hydrogel tanks), making it difficult to apply them on a large scale in the production of consumer goods.

[0006] CN119529281A discloses a high-strength, high-elasticity organosilicon photopolymerizable 3D printing material. It uses multi-arm vinyl silicone oil, a polysiloxane polymer containing silanol groups, fillers, and a photoinitiator as raw materials to obtain a photosensitive resin material, which is then 3D printed. The vinyl silicone oil used in this patent is a multi-arm vinyl silicone oil, which has excellent thermal stability, good mechanical properties, low dielectric constant, and excellent biocompatibility. However, it lacks flexibility and is unsuitable for use as a yoga mat.

[0007] CN104559196A discloses a photopolymerizable 3D printing material comprising the following components by mass percentage: 30-90% vinyl-containing organopolysiloxane, 5-30% silane-hydrogen-bonded organopolysiloxane, 0.001-10% photoinitiator, 0.1-20% reinforcing filler, and 0.5-10% additives. However, the mechanical properties of this organosilicon material are significantly inferior to those of addition-cure silicone rubber, exhibiting relatively poor tensile strength and elongation at break, making it unsuitable for use as a yoga mat.

[0008] Dual-nozzle (body material plus support material) extrusion 3D printing technology can print complex patterns, but it suffers from problems such as difficulty in removing the support material, interface material mixing, damage to appearance and performance, and high equipment costs. In contrast, single-nozzle 3D printing technology has advantages such as low equipment cost, no need to remove support material, and simplified manufacturing process, which helps to improve manufacturing efficiency and reduce costs. At the same time, reducing the support structure can improve the surface quality of the product, reduce the risk of defects, and significantly expand the freedom of structural design, enabling the direct printing of complex cantilever, honeycomb, or gradient cavity structures. However, single-nozzle 3D printing faces challenges such as a small maximum unsupported cantilever length and difficulty in meeting comprehensive mechanical performance standards, which limits the complexity of printed patterns. Therefore, increasing the maximum unsupported cantilever length of 3D printing materials is a key technical approach to achieving high degree of freedom design and reliable performance. Summary of the Invention

[0009] This invention addresses the manufacturing needs of 3D printed silicone pads by employing a platinum-catalyzed silicone addition-type formulation combined with a single-nozzle silicone extrusion 3D printing process. Through system formulation design, the maximum unsupported cantilever length during the printing process is significantly increased. This invention's technical solution not only ensures the excellent performance of the silicone pad but also expands the freedom of structural design, reduces support materials and post-processing steps, ultimately achieving a high-efficiency, low-cost, and highly reliable production solution.

[0010] Specifically, the present invention achieves the above objectives through the following technical solutions:

[0011] The first objective of this invention is to provide a silicone-based 3D printing mat material, wherein the 3D printing mat material is obtained by extruding a silicone composition into a precursor with a hollow pattern using a 3D printer, and the precursor is cured under heating conditions; the silicone composition comprises the following raw materials in parts by weight:

[0012] 50-80 parts vinyl-terminated polydimethylsiloxane,

[0013] 0.3-10 parts of hydrogen-containing silicone oil,

[0014] 20-40 parts fumed silica,

[0015] 0.001-0.1 parts platinum catalyst,

[0016] 0-0.1 doses of inhibitor, and

[0017] 0.2-5 parts thixotropic agent;

[0018] Wherein, the viscosity of the vinyl-terminated polydimethylsiloxane is ≥1500 mpa.s.

[0019] Preferably, the organosilicon composition comprises the following raw materials in parts by weight:

[0020] 50-80 parts vinyl-terminated polydimethylsiloxane,

[0021] 2-7 parts of hydrogen-containing silicone oil,

[0022] 20-40 parts fumed silica,

[0023] 0.001-0.01 parts platinum catalyst,

[0024] 0-0.1 doses of inhibitor, and

[0025] 0.2-5 parts thixotropic agent.

[0026] According to the formulation of the organosilicon composition of the present invention, the maximum unsupported cantilever length of the 3D printing pad is 2D or more, where D is the nozzle diameter; preferably, the maximum unsupported cantilever length of the 3D printing pad is 2.5D or more, and more preferably, the maximum unsupported cantilever length of the 3D printing pad is 3D or more.

[0027] The maximum unsupported cantilever length refers to the maximum horizontal projection distance from the fixed end to the free end of the cantilever under a given printing formula and process parameters. Within this distance, the structure can maintain its designed shape without significant sagging, warping, or collapse during printing and subsequent curing / cooling without any support material. Cantilevers exceeding this critical length require additional support or design adjustments. Furthermore, the mechanical properties of the cured 3D printing material must meet the following requirements: hardness ≥ 10 SHORE A, tensile strength ≥ 2 MPa, tear strength ≥ 5 N / mm, and elongation at break ≥ 200%. For example, if the nozzle diameter (D) of a 3D printer is 1 mm, and the cured length of a single-layer extruded 3D printing material is 2 mm, the cured material meets the above mechanical performance indicators. However, if the cured length of the single-layer extruded 3D printing material increases to 2.1 mm, significant sagging, warping, or collapse occurs. Alternatively, if the cured material cannot simultaneously meet the above mechanical performance indicators, then the maximum unsupported cantilever length of the material is 2 mm, which is twice the nozzle diameter (2D).

[0028] Furthermore, the vinyl content of the vinyl-terminated polydimethylsiloxane is 0.1-0.5 g / 100 g, and the silane content of the hydrosilicone oil is 5-20 g / 100 g. The amounts of vinyl-terminated polydimethylsiloxane and hydrosilicone oil satisfy the ratio of vinyl-terminated polydimethylsiloxane mass × vinyl content : hydrosilicone oil mass × silane content = 1:1-3, preferably 1:1.2-2.6; or, the amounts of vinyl-terminated polydimethylsiloxane and hydrosilicone oil satisfy the molar ratio of vinyl to silane is 1:1-3, preferably 1:1.2-3, for example 1:2.2-2.5.

[0029] Further, the organosilicon composition comprises 60-75 parts of vinyl-terminated polydimethylsiloxane, and the hydrogen-containing silicone oil comprises 0.3-1 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil. Preferably, the hydrogen-containing silicone oil comprises 0.3-0.6 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil. More preferably, the hydrogen-containing silicone oil comprises 0.3-0.5 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil.

[0030] Furthermore, the viscosity of vinyl-terminated polydimethylsiloxane is 1500-60000 mpa.s; the vinyl content of vinyl-terminated polydimethylsiloxane is 0.1-0.5 g / 100 g; the silane content of side-chain hydrogen-containing silicone oil is 15-20 g / 100 g; and the silane content of terminal hydrogen-containing silicone oil is 3-5.5 g / 100 g.

[0031] Furthermore, the BET specific surface area of ​​fumed silica is 170-260 m². 2 / g, preferably 200-240m 2 / g, for example, 220m 2 / g. More preferably, fumed silica accounts for 20-40 wt% of the organosilicon composition formulation, more preferably 20-30 wt%, for example 20-27 wt%. Increasing the mass percentage of fumed silica is beneficial for increasing the maximum unsupported cantilever length. However, it needs to be controlled within a suitable range: if the percentage is too low, the strength will decrease, and the goal of increasing the maximum unsupported cantilever length cannot be achieved; if the percentage is too high, the viscosity will be too high, making extrusion difficult during the printing process.

[0032] Furthermore, the platinum catalyst is selected from at least one of platinum catalysts, Pt / C catalysts, chloroplatinic acid, Castells catalysts, Speier catalysts, and platinum acetylacetonate.

[0033] Furthermore, the inhibitor is selected from at least one of ethynylcyclohexanol, methylbutynol, 3,5-dimethyl-1-hexynyl-3-ol, 3-methyl-1-dodecyn-3-ol, and tetramethyltetravinylcyclotetrasiloxane.

[0034] Furthermore, the thixotropic agent is selected from at least one of phenyl silicone oil and polyether silicone oil.

[0035] The second objective of this invention is to provide a method for preparing the aforementioned silicone-based 3D printing pad, comprising the following steps:

[0036] (S1) Vinyl-terminated polydimethylsiloxane and fumed silica are mixed evenly under vacuum in a planetary mixer. Hydrogen-containing silicone oil, platinum catalyst, inhibitor, and thixotropic agent are added. The mixture is then mixed evenly under vacuum and degassed to obtain the printing material.

[0037] (S2) The printing material is loaded into the 3D printer and 3D printing is performed according to the set program. After printing is completed, it is heated and cured to prepare a silicone-based 3D printing pad.

[0038] Furthermore, in step (S1), the uniform mixing under vacuum conditions is completed at a vacuum degree of 0.05-0.09 MPa and a rotation speed of 200-400 rpm.

[0039] Further, in step (S2), the 3D printing parameters are set as follows: nozzle diameter 0.3-3mm, preferably 1-1.5mm; fill ratio 20-40%, preferably 25-30%; extrusion pressure 0.1-0.8Mpa, preferably 0.3-0.5MPa; printing speed 10-70mm / s, preferably 30-50mm / s.

[0040] Furthermore, in step (S2), the heating curing conditions are 100-150℃ for 0.5-3 hours, such as 150℃ for 1 hour, to ensure that the hydrosilylation reaction is complete and to obtain a fully cured 3D printing pad material.

[0041] Compared with the prior art, the present invention achieves the following beneficial effects:

[0042] I. Through optimization of the silicone composition formulation, a 3D printing silicone precursor that balances hardness and flexibility was obtained. Using this precursor as raw material, after obtaining the desired pattern through 3D printing, the maximum unsupported cantilever length of the cured material was significantly increased while maintaining both material hardness and toughness. This enables the silicone composition based on hydrosilylation to be used to produce lightweight, customizable textured 3D printed pads without the need for supports. It is suitable for use as 3D printed pads such as yoga mats and bicycle seats that require weight reduction, customizable support patterns, and zoned cushioning.

[0043] Second, this invention uses vinyl-terminated polydimethylsiloxane with suitable viscosity, which can increase the maximum unsupported cantilever length. If the viscosity is too low, the elongation at break of the 3D printing material will decrease after curing; if the viscosity is too high, extrusion will be difficult during the 3D printing process, and the material will become brittle.

[0044] Third, in the organosilicon composition formulation of the present invention, the content of fumed silica is above 20 wt%, which is beneficial to increasing the maximum unsupported cantilever length.

[0045] Fourth, the inventors were also surprised to discover that the hydrogen-containing silicone oil, which is a mixture of side-chain hydrogen-containing silicone oil and end-chain hydrogen-containing silicone oil in a certain proportion, can maximize the maximum length of the unsupported cantilever, reaching more than 3 times the nozzle diameter. Attached Figure Description

[0046] Figure 1 This is a photograph of the 3D printed pad material prepared in Example 1. Detailed Implementation

[0047] The technical solution of the present invention will be further explained and described below with reference to specific embodiments.

[0048] Example 1

[0049] (S1) Take 71.4 parts by weight of vinyl-terminated polydimethylsiloxane (viscosity 1500 mPa·s, alkenyl content 0.26 g / 100 g), and add 20 parts by weight of fumed silica (BET comparison surface area 200 m²). 2 The mixture (g) was vacuum-dispersed uniformly in a planetary mixer under a vacuum of 0.05 MPa at 300 rpm. Then, 0.5 parts by weight of side-chain hydrogen-containing silicone oil (20 g / 100 g silicon-hydrogen content), 6.5 parts by weight of end-chain hydrogen-containing silicone oil (5.5 g / 100 g silicon-hydrogen content), 0.01 parts by weight of platinum catalyst, 0.09 parts by weight of ethynylcyclohexanol, and 1.5 parts by weight of polyether silicone oil were added. The mixture was then vacuum-mixed uniformly under a vacuum of 0.05 MPa at 300 rpm to remove air bubbles, thus obtaining the printing material.

[0050] (S2) The printing material is loaded into the STSW-556 printer using a 1.5mm diameter nozzle. The fill ratio is 30%. The extrusion pressure is 0.4MPa, and the printing speed is 50mm / s. After printing, the material is placed in a 120℃ oven for 30 minutes to ensure complete hydrosilylation reaction, resulting in a fully cured 3D printed pad. The photograph is shown below. Figure 1 As shown.

[0051] Tests showed that, under the following mechanical properties: hardness ≥ 10 SHORE A, tensile strength ≥ 2 MPa, tear strength ≥ 5 N / mm, and elongation at break ≥ 200%, the maximum unsupported cantilever length is approximately 5 mm, i.e., 3.33D (D = 1.5 mm).

[0052] Example 2

[0053] Other conditions are the same as in Example 1, except that step (S1) is changed to: taking 59.4 parts by weight of vinyl-terminated polydimethylsiloxane (viscosity 1500 mPa·s, alkenyl content 0.26 g / 100 g), taking 8 parts by weight of vinyl-terminated polydimethylsiloxane (viscosity 60000 mPa·s), and adding 24 parts by weight of fumed silica (BET comparison surface area 220 m²). 2 The mixture (g) was vacuum-dispersed uniformly in a planetary mixer under a vacuum of 0.05 MPa at 300 rpm. Then, 0.5 parts by weight of side-chain hydrogen-containing silicone oil (20 g / 100 g silicon-hydrogen content), 6.5 parts by weight of end-chain hydrogen-containing silicone oil (5.5 g / 100 g silicon-hydrogen content), 0.01 parts by weight of platinum catalyst, 0.09 parts by weight of ethynylcyclohexanol, and 1 part by weight of polyether silicone oil were added. The mixture was then vacuum-mixed uniformly under a vacuum of 0.05 MPa at 300 rpm to remove air bubbles, thus obtaining the printing material.

[0054] The obtained 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was 5.5 mm, or 3.67D.

[0055] Example 3

[0056] Other conditions are the same as in Example 1, except that step (S1) is changed to: taking 75 parts by weight of vinyl-terminated polydimethylsiloxane (viscosity 1500 mPa·s, alkenyl content 0.26 g / 100 g), and adding 30 parts by weight of fumed silica (BET comparison surface area 200 m²). 2 The mixture (g) was vacuum-dispersed uniformly in a planetary mixer under a vacuum of 0.05 MPa and a rotation speed of 300 rpm. Then, 0.6 parts by weight of side-chain hydrogen-containing silicone oil (20 g / 100 g silicon hydrogen content), 7.0 parts by weight of end-chain hydrogen-containing silicone oil (3.5 g / 100 g silicon hydrogen content), 0.01 parts by weight of platinum catalyst, 0.09 parts by weight of ethynylcyclohexanol, and 2.6 parts by weight of phenyl silicone oil were added. The mixture was then vacuum-mixed uniformly under a vacuum of 0.05 MPa and a rotation speed of 300 rpm to remove air bubbles, thus obtaining the printing material.

[0057] The obtained 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was 4.7 mm, or 3.1D.

[0058] Example 4

[0059] Other conditions are the same as in Example 1, except that step (S1) is changed to: taking 60 parts by weight of vinyl-terminated polydimethylsiloxane (viscosity 1500 mPa·s, alkenyl content 0.26 g / 100 g), and adding 20 parts by weight of fumed silica (BET comparison surface area 200 m²). 2 The mixture (g) was vacuum-dispersed uniformly in a planetary mixer under a vacuum of 0.05 MPa and a rotation speed of 300 rpm. Then, 0.3 parts by weight of side-chain hydrogen-containing silicone oil (20 g / 100 g silicon hydrogen content), 5 parts by weight of end-chain hydrogen-containing silicone oil (5.5 g / 100 g silicon hydrogen content), 0.01 parts by weight of platinum catalyst, 0.09 parts by weight of ethynylcyclohexanol, and 1.5 parts by weight of polyether silicone oil were added. The mixture was then vacuum-mixed uniformly under a vacuum of 0.05 MPa and a rotation speed of 300 rpm to remove air bubbles, thus obtaining the printing material.

[0060] The obtained 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was 5.2 mm, or 3.47D.

[0061] Example 5

[0062] Other conditions were the same as in Example 1, except that in step (S1), no end-chain hydrogen-containing silicone oil was added, and the amount of side-chain hydrogen-containing silicone oil added was changed to 2.3 parts by mass. The resulting 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was approximately 4.2 mm, or 2.8D.

[0063] Comparative Example 1

[0064] Other conditions were the same as in Example 1, except that in step (S1), the viscosity of the vinyl-terminated polydimethylsiloxane was 600 mPa·s. The resulting 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was 2.8 mm.

[0065] Comparative Example 2

[0066] The other conditions were the same as in Example 1, except that in step (S1), the amount of fumed silica was changed to 10 parts by mass. The resulting 3D printing material was tested under the same conditions as in Example 1, and the maximum unsupported cantilever length was 1.3 mm.

[0067] Comparative Example 3

[0068] The other conditions are the same as in Example 1, except that in step (S1), no side-chain hydrogen-containing silicone oil is added, and the amount of end-chain hydrogen-containing silicone oil is 8.3 parts by mass. The resulting 3D printing material was tested under the same conditions as in Example 1, but it could not be effectively formed, and the maximum unsupported cantilever length could not be tested.

Claims

1. A silicone-based 3D printing pad material, characterized in that, The 3D printed pad material is a precursor formed by extruding a silicone composition using a 3D printer to create a hollow pattern, and the precursor is cured under heating conditions; the silicone composition comprises the following raw materials in parts by weight: 50-80 parts vinyl-terminated polydimethylsiloxane, 0.3-10 parts of hydrogen-containing silicone oil, 20-40 parts fumed silica, 0.001-0.1 parts platinum catalyst, 0-0.1 doses of inhibitor, and 0.2-5 parts thixotropic agent; The vinyl-terminated polydimethylsiloxane has a viscosity of 1500-300000 mpa.s.

2. The silicone-based 3D printing pad material according to claim 1, characterized in that, The vinyl content of the vinyl-terminated polydimethylsiloxane is 0.1-0.5 g / 100 g, and the silane content of the hydrogen-containing silicone oil is 5-20 g / 100 g. The amounts of vinyl-terminated polydimethylsiloxane and hydrogen-containing silicone oil satisfy the ratio of vinyl-terminated polydimethylsiloxane mass × vinyl content : hydrogen-containing silicone oil mass × silane content = 1:1-3, preferably 1:1.2-2.

6.

3. The silicone-based 3D printing pad material according to claim 1 or 2, characterized in that, The organosilicon composition comprises 60-75 parts of vinyl-terminated polydimethylsiloxane, and the hydrogen-containing silicone oil comprises 0.3-1 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil. Preferably, the hydrogen-containing silicone oil comprises 0.3-0.6 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil. More preferably, the hydrogen-containing silicone oil comprises 0.3-0.5 parts by weight of side-chain hydrogen-containing silicone oil and 5-6.5 parts by weight of terminal hydrogen-containing silicone oil.

4. The silicone-based 3D printing pad material according to any one of claims 1-3, characterized in that, The viscosity of the vinyl-terminated polydimethylsiloxane is 1500-60000 mpa.s; the silane content of the side-chain hydrogen-containing silicone oil is 15-20 g / 100 g, and the silane content of the end-terminated hydrogen-containing silicone oil is 3-5.5 g / 100 g.

5. The silicone-based 3D printing pad material according to any one of claims 1-4, characterized in that, The fumed silica comprises 20-40 wt% of the organosilicon composition, preferably 20-30 wt%; the BET specific surface area of ​​the fumed silica is 170-260 m². 2 / g, preferably 200-240m 2 / g.

6. The silicone-based 3D printing pad material according to any one of claims 1-5, characterized in that, The platinum catalyst is selected from at least one of platinum catalyst, Pt / C catalyst, chloroplatinic acid, Castells catalyst, Speier catalyst, and platinum acetylacetonate.

7. The silicone-based 3D printing pad material according to any one of claims 1-6, characterized in that, The inhibitor is selected from at least one of ethynylcyclohexanol, methylbutynol, 3,5-dimethyl-1-hexynyl-3-ol, 3-methyl-1-dodecynyl-3-ol, and tetramethyltetravinylcyclotetrasiloxane; and / or, The thixotropic agent is selected from at least one of phenyl silicone oil and polyether silicone oil.

8. The silicone-based 3D printing pad material according to any one of claims 1-7, characterized in that, The maximum unsupported cantilever length of the 3D printed pad material is 2D or more, where D is the nozzle diameter; preferably, the maximum unsupported cantilever length of the 3D printed pad material is 2.5D or more, and more preferably, the maximum unsupported cantilever length of the 3D printed pad material is 3D or more.

9. The method for preparing the silicone-based 3D printing pad material according to any one of claims 1-8, characterized in that, Includes the following steps: (S1) Vinyl-terminated polydimethylsiloxane and fumed silica are mixed evenly under vacuum in a planetary mixer. Hydrogen-containing silicone oil, platinum catalyst, inhibitor and thixotropic agent are added. The mixture is then mixed evenly under vacuum and degassed to obtain the printing material. (S2) The printing material is loaded into the 3D printer and 3D printing is performed according to the set program. After printing is completed, it is heated and cured to prepare a silicone-based 3D printing pad.

10. The preparation method according to claim 9, characterized in that, In step (S1), the uniform mixing under vacuum conditions is completed at a vacuum level of 0.05-0.09 MPa and a rotation speed of 200-400 rpm; and / or, In step (S2), the 3D printing parameters are set as follows: nozzle diameter 0.3-3mm, preferably 1-1.5mm; fill ratio 20-40%, preferably 25-30%; extrusion pressure 0.1-0.8MPa, preferably 0.3-0.5MPa; printing speed 10-70mm / s, preferably 30-50mm / s; furthermore, in step (S2), the heat curing condition is 100-150℃ for 0.5-3h.

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