Single-component 3D printing photosensitive resin, elastomer material and preparation method

Abstract

The invention provides a single-component 3D printing photosensitive resin, an elastomer material and a preparation method, and relates to the technical field of 3D printing. The single-component 3D printing photosensitive resin is prepared from the following raw materials in parts by mass: 10 to 25 parts of closed diisocyanate, 30 to 70 parts of acrylic acid modified polyamine, 20 to 40 parts of reactive diluent and 2 to 5 parts of photoinitiator, the structural formula of the closed diisocyanate is as shown in a formula I, and the structural formula of the acrylic acid modified polyamine is as shown in a formula II. The dual-curing process of the single-component 3D printing photosensitive resin system has the rapid prototyping advantage of photocuring and the deep chain extension advantage of thermocuring, so that the finally obtained elastomer material has higher molecular weight and more excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a single-component 3D printing photosensitive resin, an elastomer material and a preparation method thereof. Background Art

[0002] At present, 3D printing photosensitive resin elastomer materials are widely used in flexible electronics, biomedicine, soft robots and other fields, and they generally adopt a two-component curing strategy. Patent CN 114479001 A discloses a two-component polyurethane mixture. However, this two-component curing strategy has many problems. It requires the photocurable prepolymer and the heat-curing component to be packaged and stored separately, and accurately measured and mixed when used. Not only is the process complicated, but it is also easy to cause incomplete curing and unstable performance of 3D printed products due to proportion deviation or uneven mixing. The storage conditions of the heat-curing component are harsh and easy to be deactivated in advance, which increases the material cost and process difficulty. In contrast, the single-component dual-curing photosensitive resin integrates the photocurable active functional group and the closed heat-curable active functional group into the same system through molecular structure design. When used, 3D printing can be directly performed without pre-mixing, which greatly simplifies the 3D printing production process. At the same time, the closed heat-curing functional group in the single-component photosensitive resin system has excellent stability at room temperature, which can effectively avoid spontaneous reaction during storage, extend the shelf life of the photosensitive resin, and reduce the storage and transportation cost of the photosensitive resin. In addition, the single-component photosensitive resin system can also achieve rapid shaping and cross-linking density regulation through different curing stages, optimize the mechanical properties and heat resistance of the material, and has more advantages in industrial production, which is suitable for 3D printing application scenarios with strict requirements on process simplification and material consistency. Summary of the invention

[0003] The purpose of the present invention is to provide a single-component 3D printing photosensitive resin, elastomeric material and preparation method. The photosensitive resin system of the present invention is subjected to a dual curing process of photocuring and thermal curing to obtain an elastomeric material. In the photocuring stage, the acrylate double bonds in the photosensitive resin system undergo a cross-linking reaction, allowing the material to be rapidly formed; in the thermal curing stage, the blocked diisocyanate is unblocked by heat and reacts with the amino group in the acrylic modified polyamine to perform deep chain extension, ultimately obtaining an elastomeric material product with excellent performance.

[0004] The present invention first provides a single-component 3D printing photosensitive resin, which includes the following raw materials in parts by mass:

[0005] 10-25 parts of blocked diisocyanate, 30-70 parts of acrylic modified polyamine, 20-40 parts of reactive diluent, 2-5 parts of photoinitiator;

[0006] The structural formula of the blocked diisocyanate is shown in Formula I:

[0007] Formula Ⅰ;

[0008] The structural formula of the acrylic acid modified polyamine is as shown in Formula Ⅱ:

[0009] Formula Ⅱ;

[0010] In Formula Ⅱ, n1 = 1 to 20, n2 = 1 to 20, n3 = 1 to 20.

[0011] Preferably, the active diluent is 2-methyl-1,3-propanediol diacrylate.

[0012] Preferably, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0013] The present invention also provides a preparation method of the above-mentioned one-component 3D printing photosensitive resin, including:

[0014] Step 1: Add hexamethylene diisocyanate, phenol, a catalyst and a solvent into a reaction vessel, carry out a reaction, and obtain a blocked diisocyanate shown in Formula Ⅰ;

[0015] Formula Ⅰ;

[0016] Step 2: Dissolve methacrylic acid and hydroquinone in a solvent to obtain a monomer solution. Under nitrogen protection, add a ternary amine containing a flexible aliphatic chain structure and a catalyst into the reaction vessel. After cooling the reaction system to 0 to 5 °C in an ice-water bath, drop the above monomer solution into the reaction vessel. After the dropping is completed, allow the reaction system to naturally warm up to room temperature and continue the reaction for 4 to 6 hours. After post-treatment, an acrylic acid modified polyamine shown in Formula Ⅱ is obtained;

[0017] Formula Ⅱ;

[0018] In Formula Ⅱ, n1 = 1 to 20, n2 = 1 to 20, n3 = 1 to 20;

[0019] Step 3: Mix the blocked diisocyanate prepared in Step 1, the acrylic acid modified polyamine prepared in Step 2, the active diluent and the photoinitiator to obtain a one-component 3D printing photosensitive resin.

[0020] Preferably, the molar ratio of hexamethylene diisocyanate to phenol in Step 1 is 1: (2 to 2.2).

[0021] Preferably, the reaction temperature in Step 1 is 60 to 80 °C, and the reaction time is 2 to 4 hours.

[0022] Preferably, in the step 2, the molar ratio of the triamine containing a flexible fatty chain structure to methacrylic acid is 1:(1-1.2).

[0023] The present invention also provides an elastomeric material, comprising the above-mentioned single-component 3D printing photosensitive resin.

[0024] The present invention also provides a method for preparing an elastomeric material, comprising:

[0025] Step 1: Place the single-component 3D printing photosensitive resin in the resin tank of the 3D printer and perform photocuring to obtain a photocured product;

[0026] Step 2: thermally cure the photocured product of step 1 to obtain an elastomeric material.

[0027] Preferably, the thermal curing in step 2 is preheated in an oven at 80-100° C. for 0.5-2 hours, and then heated to 120-150° C. and maintained for 1-2 hours.

[0028] Beneficial effects of the present invention

[0029] The present invention provides a one-component 3D printing photosensitive resin, an elastomer material and a preparation method. The one-component 3D printing photosensitive resin of the present invention is composed of an acrylic acid modified polyamine, a blocked diisocyanate, a dibasic acrylate reactive diluent and a photoinitiator. In the photocuring stage, the acrylate double bonds in the photosensitive resin system undergo a cross-linking reaction, so that the material is rapidly formed; in the thermal curing stage, the blocked diisocyanate is unblocked by heat and reacts with the amino group in the acrylic acid modified polyamine to perform deep chain extension, and finally obtains an elastomer material product. The dual curing process of the above-mentioned one-component 3D printing photosensitive resin system has both the rapid prototyping advantages of photocuring and the deep chain extension advantages of thermal curing, so that the finally obtained elastomer material has a higher molecular weight and better mechanical properties. In addition, the blocked diisocyanate in the one-component 3D printing photosensitive resin system has excellent stability at room temperature, and can only be unblocked and show reactive activity in a high temperature environment, and then undergoes a chain extension reaction with the acrylic acid modified polyamine to form a high molecular weight polyurethane elastomer material. Therefore, the single-component photosensitive resin system exhibits excellent stability when stored at room temperature, can avoid the problem of spontaneous curing and deterioration during storage, extend the storage period of the photosensitive resin, relax its storage conditions, and thus significantly reduce the storage and transportation costs and use complexity of the photosensitive resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the H-NMR spectrum of the blocked diisocyanate of formula I prepared in Example 1 of the present invention;

[0031] Figure 21H NMR spectrum of the methacrylamide diamine of the structure of Formula II prepared in Example 1 of the present invention;

[0032] Figure 3 Tensile strength curve of the elastomeric material in Example 1 of the present invention;

[0033] Figure 4 Tensile strength curve of the elastomeric material in Example 2 of the present invention;

[0034] Figure 5 Tensile strength curve of the elastomeric material in Example 3 of the present invention;

[0035] Figure 6 Viscosity change curve of the photosensitive resin in Examples 1-3 of the present invention;

[0036] Figure 7 Viscosity change curve of the photosensitive resin in Comparative Example 1. Detailed implementation manners

[0037] The present invention first provides a one-component 3D printing photosensitive resin, which comprises the following raw materials in parts by mass:

[0038] 10-25 parts of blocked diisocyanate, 30-70 parts of acrylic modified polyamine, 20-40 parts of active diluent, 2-5 parts of photoinitiator;

[0039] The blocked diisocyanate has the structural formula shown in Formula I:

[0040] Formula I;

[0041] The acrylic modified polyamine has the structural formula shown in Formula II:

[0042] Formula II;

[0043] In Formula II, n1 = 1-20, n2 = 1-20, n3 = 1-20.

[0044] According to the present invention, the active diluent is preferably 2-methyl-1,3-propanediol diacrylate (MPDDA), and the photoinitiator is preferably diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0045] The present invention also provides a preparation method of the one-component 3D printing photosensitive resin, which specifically comprises:

[0046] Step 1: At room temperature, add hexamethylene diisocyanate (HDI), phenol, a catalyst, and an anhydrous solvent into a reaction vessel. Under nitrogen protection, conduct the reaction. Preferably, the reaction system is slowly heated to 60 - 80 °C and kept at a constant temperature for 2 - 4 hours. During the reaction process, the solvent is refluxed through a condenser and continuously stirred to ensure full reaction. After the reaction is completed, the system is cooled to room temperature, and then the solvent toluene is removed by vacuum distillation. Finally, a blocked diisocyanate shown in Formula I in the form of a light yellow viscous substance is obtained. The preferred catalyst is dibutyltin dilaurate, the preferred anhydrous solvent is toluene, the molar ratio of hexamethylene diisocyanate to phenol is preferably 1:(2 - 2.2); the dosage of the catalyst dibutyltin dilaurate is preferably 0.3% - 0.5% of the mass of hexamethylene diisocyanate. The reaction process is as follows:

[0047]

[0048] Step 2: Dissolve methacrylic acid and the inhibitor hydroquinone in a solvent. The preferred solvent is anhydrous tetrahydrofuran to obtain a monomer solution, which is transferred to a constant pressure dropping funnel for standby. Under nitrogen protection, add a ternary amine with a flexible aliphatic chain structure and a catalyst into the reaction vessel. After the reaction system is cooled to 0 - 5 °C in an ice - water bath, preferably, the monomer solution is slowly dropped at a rate of 1 - 2 drops per second, controlling the reaction temperature not to exceed 10 °C. After the dropping is completed, the ice bath is removed, and the reaction system is allowed to naturally warm up to room temperature and continue to react for 4 - 6 hours. After the reaction is completed, through post - treatment, the preferred post - treatment process is: First, filter to remove the solid triethylamine hydrochloride formed. The filtrate is washed successively with 5% sodium bicarbonate solution and deionized water until neutral. After drying over anhydrous sodium sulfate, the solvent is removed by vacuum distillation to obtain a crude product, which is purified by silica gel column chromatography. After collecting the target component, it is concentrated by rotary evaporation, and finally vacuum - dried at 40 °C for 24 hours to obtain the target product methacrylamide diamine in the form of a light yellow viscous substance. The preferred catalyst is triethylamine, the preferred ternary amine with a flexible aliphatic chain structure is N-(1-(1,1 - bis(2 - aminopropoxy)ethoxy)propan - 2 - yl)methacrylamide, the molar ratio of the ternary amine with a flexible aliphatic chain structure to methacrylic acid is preferably 1:(1 - 1.2); the dosage of hydroquinone is preferably 0.5% - 1% of the mass of methacrylic acid; the molar ratio of methacrylic acid to the catalyst triethylamine is preferably 1:(1 - 1.2). The reaction process is as follows:

[0049]

[0050] Step 3: Mix the blocked diisocyanate prepared in Step 1, the acrylic - modified polyamine prepared in Step 2, an active diluent, and a photoinitiator. The mixing preferably uses magnetic stirring to fully mix each component at room temperature until a uniform and transparent photosensitive resin is formed.

[0051] The present invention also provides an elastomeric material, comprising the above-mentioned single-component 3D printing photosensitive resin.

[0052] The present invention also provides a method for preparing an elastomeric material, comprising:

[0053] Step 1: Place a single-component 3D printing photosensitive resin in an ultra-high-speed and high-precision 3D printer resin tank, preferably using 405nm ultraviolet light for layer-by-layer exposure and curing to obtain a photocured product, including a structure as shown in Formula III:

[0054] Formula III;

[0055] In formula III, n1=1~20, n2=1~20, n3=1~20.

[0056] The reaction process is as follows:

[0057]

[0058] Step 2: The photocured product formed in step 1 is preferably placed in an oven at 80-100° C. for preheating for 0.5-2 hours, and then heated to 120-150° C. for 1-2 hours. During this process, the blocked diisocyanate is unblocked to release active isocyanate groups, which undergo chain extension reaction with the amino groups on the methacrylamide diamine molecular chain in the photocurable network to obtain an elastomeric material, including a structure as shown in Formula IV:

[0059] Formula IV;

[0060] In formula IV, n1=1~20, n2=1~20, n3=1~20, n4=5~200.

[0061] The reaction process is as follows:

[0062]

[0063]

[0064] The present invention is further described in detail below with reference to specific examples, and the raw materials involved in the examples are all commercially available.

[0065] Example 1

[0066] 1) Under normal temperature conditions, hexamethylene diisocyanate (HDI) (16.82 g), phenol (18.82 g), the catalyst dibutyltin dilaurate (0.08 g), and the anhydrous solvent toluene (100 mL) were successively added to a three-necked flask equipped with a thermometer, a mechanical stirrer, and a condenser. Under nitrogen protection, the reaction system was slowly heated to 80 °C and maintained at a constant temperature for 4 hours. During the reaction, the solvent was refluxed through the condenser and continuously stirred to ensure full progress of the reaction. After the reaction was completed, the system was cooled to room temperature, and then the solvent toluene was removed by vacuum distillation, and finally a yellowish viscous blocked diisocyanate product was obtained. The NMR spectrum is as Figure 1 shown.

[0067] 2) Under nitrogen protection, N-(1-(1,1-bis(2-aminopropoxy)ethoxy)propan-2-yl)methacrylamide (29.88 g) and the catalyst triethylamine (12.00 g) were added to a three-necked flask equipped with a mechanical stirrer, a thermometer, and a reflux condenser. Separately, methacrylic acid (10.40 mL) and the inhibitor hydroquinone (0.12 g) were dissolved in anhydrous tetrahydrofuran (300 mL), transferred to a constant-pressure dropping funnel for standby. After the reaction system was cooled to 0 °C in an ice-water bath, the monomer solution was slowly dropped at a rate of 1 - 2 drops / second, controlling the reaction temperature not to exceed 10 °C. After the dropping was completed, the ice bath was removed, and the reaction system was allowed to warm up to room temperature naturally and continue to react for 4 hours. After the reaction was completed, first, the solid triethylamine hydrochloride formed was removed by filtration. The filtrate was washed successively with 5% sodium bicarbonate solution and deionized water until neutral. After drying over anhydrous sodium sulfate, the solvent was removed by vacuum distillation to obtain a crude product. Purification was carried out by silica gel column chromatography. After collecting the target component, it was concentrated by rotary evaporation, and finally vacuum dried at 40 °C for 24 hours to obtain the target product methacrylamide diamine as a pale yellow viscous substance. The NMR spectrum is as Figure 2 shown.

[0068] 3) The photosensitive methacrylamide diamine (40 g), 2-methyl-1,3-propanediol diacrylate (MPDDA) (35 g), the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) (3 g), and the above-obtained blocked diisocyanate (23.5 g) were mixed to form a uniformly transparent photosensitive resin system.

[0069] 4) Subsequently, the photosensitive resin was placed in the resin tank of an ultra-high-speed and high-precision 3D printer, and layer-by-layer exposure curing was carried out using 405 nm ultraviolet light to obtain a photocured product.

[0070] 5) The formed photocured product is first preheated in an oven at 80°C for 30 minutes, and then heated to 140°C for 2 hours. During this process, the blocked diisocyanate is unblocked, releasing active isocyanate groups, which undergo chain extension reactions with the amino groups on the methacrylamide diamine molecular chains in the photocuring network to obtain an elastomer material.

[0071] The tensile strength of the elastomeric material obtained in Example 1 is 30 MPa, and the elongation at break is 229%. The tensile strength curve is as follows: Figure 3 As shown, this is due to the dual curing mechanism, which combines the rapid prototyping advantages of light curing and the deep chain extension advantages of thermal curing, so that the cured resin has a higher molecular weight and excellent mechanical properties.

[0072] Example 2

[0073] 1) At room temperature, hexamethylene diisocyanate (HDI) (16.82 g), phenol (19.76 g), catalyst dibutyltin dilaurate (0.08 g) and anhydrous solvent toluene (100 mL) were added to a three-necked flask equipped with a thermometer, a mechanical stirrer and a condenser. Under nitrogen protection, the reaction system was slowly heated to 80 ° C and kept at a constant temperature for 4 hours. During the reaction, the solvent was refluxed through the condenser and stirred continuously to ensure that the reaction was fully carried out. After the reaction was completed, the system was cooled to room temperature, and then the solvent toluene was removed by reduced pressure distillation to finally obtain a light yellow viscous blocked diisocyanate product.

[0074] 2) Under nitrogen protection, add N-(1-(1,1-bis(2-aminopropoxy)ethoxy)prop-2-yl)methacrylamide (29.88 g) and catalyst triethylamine (12.00 g) to a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Separately, dissolve methacrylic acid (10.40 mL) and inhibitor hydroquinone (0.12 g) in anhydrous tetrahydrofuran (300 mL) and transfer to a constant pressure dropping funnel for use. After the reaction system is placed in an ice water bath and cooled to 0°C, slowly add the monomer solution at a rate of 1 to 2 drops / second, and control the reaction temperature not to exceed 10°C. After the addition is completed, remove the ice bath, allow the reaction system to naturally warm to room temperature and continue the reaction for 4 hours. After the reaction is completed, first filter out the generated triethylamine hydrochloride solid. The filtrate is washed with 5% sodium bicarbonate solution and deionized water in turn until neutral. After drying over anhydrous sodium sulfate, the solvent was removed by distillation under reduced pressure to obtain a crude product. Purification was performed by silica gel column chromatography, and the target component was collected and concentrated by rotary evaporation, and finally vacuum dried at 40° C. for 24 hours to obtain the target product, methacrylamide diamine, which was a light yellow viscous product.

[0075] 3) Mix photosensitive methacrylic acid diamine (43.5 g), 2-methyl-1,3-propylene glycol diacrylate (MPDDA) (30 g), photoinitiator diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) (3 g) and the above-obtained blocked diisocyanate (25 g) to form a uniform and transparent photosensitive resin system.

[0076] 4) Subsequently, the photosensitive resin is placed in the resin tank of an ultra-high-speed and high-precision 3D printer and exposed and cured layer by layer using 405nm ultraviolet light to obtain a photocured product.

[0077] 5) The formed photocured product is first preheated in an oven at 80°C for 30 minutes, and then heated to 140°C for 2 hours. During this process, the blocked diisocyanate is unblocked, releasing active isocyanate groups, which undergo chain extension reactions with the amino groups on the methacrylamide diamine molecular chains in the photocuring network to obtain an elastomer material.

[0078] The tensile strength of the elastomeric material obtained in Example 2 is 28 MPa, and the elongation at break is 213%. The tensile strength curve is as follows: Figure 4 shown.

[0079] Example 3

[0080] 1) At room temperature, hexamethylene diisocyanate (HDI) (16.82 g), phenol (20.70 g), catalyst dibutyltin dilaurate (0.17 g) and anhydrous solvent toluene (100 mL) were added to a three-necked flask equipped with a thermometer, a mechanical stirrer and a condenser. Under nitrogen protection, the reaction system was slowly heated to 80 ° C and kept at a constant temperature for 4 hours. During the reaction, the solvent was refluxed through the condenser and stirred continuously to ensure that the reaction was fully carried out. After the reaction was completed, the system was cooled to room temperature, and then the solvent toluene was removed by reduced pressure distillation to finally obtain a light yellow viscous blocked diisocyanate product.

[0081] 2) Under nitrogen protection, add N-(1-(1,1-bis(2-aminopropoxy)ethoxy)prop-2-yl)methacrylamide (29.88 g) and catalyst triethylamine (12 g) to a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Separately, dissolve methacrylic acid (10.40 mL) and inhibitor hydroquinone (0.12 g) in anhydrous tetrahydrofuran (300 mL) and transfer to a constant pressure dropping funnel for use. After the reaction system is placed in an ice water bath and cooled to 0°C, slowly add the monomer solution at a rate of 1 to 2 drops / second, and control the reaction temperature not to exceed 10°C. After the addition is completed, remove the ice bath, allow the reaction system to naturally warm to room temperature and continue to react for 4 hours. After the reaction is completed, first filter and remove the generated triethylamine hydrochloride solid. The filtrate is washed with 5% sodium bicarbonate solution and deionized water in turn until neutral. After drying over anhydrous sodium sulfate, the solvent is removed by reduced pressure distillation to obtain a crude product. The product was purified by silica gel column chromatography, and the target component was collected and concentrated by rotary evaporation. Finally, the product was dried in vacuum at 40° C. for 24 hours to obtain the target product, methacrylamide diamine, in a light yellow viscous state.

[0082] 3) Mix photosensitive methacrylic acid diamine (50 g), 2-methyl-1,3-propylene glycol diacrylate (MPDDA) (33.5 g), photoinitiator diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) (3 g) and the above-obtained blocked diisocyanate (15 g) in a certain proportion to form a uniform and transparent photosensitive resin system.

[0083] 4) Subsequently, the photosensitive resin is placed in the resin tank of an ultra-high-speed and high-precision 3D printer and exposed and cured layer by layer using 405nm ultraviolet light to obtain a photocured product.

[0084] 5) The formed photocured product is first preheated in an oven at 80°C for 30 minutes, and then heated to 140°C for 2 hours. During this process, the blocked isocyanate is unblocked, releasing active isocyanate groups, which undergo chain extension reactions with the amino groups on the methacrylamide diamine molecular chains in the photocuring network to obtain an elastomer material.

[0085] The tensile strength of the elastomeric material obtained in Example 3 is 29 MPa, and the elongation at break is 221%. The tensile strength curve is shown in Figure 5 shown.

[0086] Shelf life test

[0087] The present invention systematically investigates the storage stability of the photosensitive resins prepared in Examples 1-3. Figure 6 As shown, Figure 6It is the viscosity change curve of the photosensitive resin in Examples 1 to 3 of the present invention. It can be seen that under the condition of storage in a sealed state at room temperature, all the samples of the examples show excellent storage stability, and their viscosities remain basically constant with the change of time. This excellent performance is attributed to the single-component system design adopted in the examples, especially the chemical blocking technology for blocking the active isocyanate groups, which effectively avoids the occurrence of side reactions during storage.

[0088] To verify the importance of the blocking treatment, the present invention designed a comparative experiment: replacing the blocked diisocyanate in the examples with unblocked hexamethylene diisocyanate (HDI) in an equivalent amount. The specific process is as follows:

[0089] Comparative Example 1

[0090] 1) Under the protection of nitrogen, add N-(1-(1,1-bis(2-aminopropoxy)ethoxy)propan-2-yl)methacrylamide (29.88 g) and the catalyst triethylamine (12 g) into a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Separately dissolve methacrylic acid (10.40 mL) and the inhibitor hydroquinone (0.12 g) in anhydrous tetrahydrofuran (300 mL), transfer it to a constant-pressure dropping funnel for standby. After cooling the reaction system to 0 °C in an ice-water bath, slowly drop the monomer solution at a rate of 1-2 drops per second, and control the reaction temperature not to exceed 10 °C. After the dropping is completed, remove the ice bath and let the reaction system naturally warm up to room temperature and continue to react for 4 hours. After the reaction is completed, first filter to remove the generated solid of triethylamine hydrochloride. The filtrate is washed with 5% sodium bicarbonate solution and deionized water in turn until neutral. After drying over anhydrous sodium sulfate, the solvent is removed by vacuum distillation to obtain a crude product. Purify it by silica gel column chromatography, collect the target component and then concentrate it by rotary evaporation, and finally dry it under vacuum at 40 °C for 24 hours to obtain the target product methacrylamide diamine in the form of a pale yellow viscous liquid.

[0091] 2) Mix photosensitive methacrylamide diamine (50 g), 2-methyl-1,3-propanediol diacrylate (MPDDA) (33.5 g), photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) (3 g) and hexamethylene diisocyanate HDI (15 g) in a certain proportion to form a uniform and transparent photosensitive resin system.

[0092] 3) Subsequently, place the photosensitive resin in the resin tank of an ultra-high-speed and high-precision 3D printer, and use 405 nm ultraviolet light for layer-by-layer exposure curing to obtain a photocured product.

[0093] 4) The formed photocured product is first preheated in an oven at 80 °C for 30 minutes, and then the temperature is raised to 140 °C and maintained for 2 hours to obtain an elastomeric material.

[0094] As Figure 7 shown, it is the viscosity change curve of the photosensitive resin in Comparative Example 1. It can be seen that these samples without blocking treatment show a significant increase in viscosity during storage, which ultimately leads to the gelation of the system and failure. This phenomenon can be attributed to the chain extension reaction of the active isocyanate groups with amino groups and moisture in the air. The results of the comparative experiments fully demonstrate the key role of isocyanate blocking treatment in ensuring the storage stability of the photosensitive resin.

Claims

1. A one-component 3D printing photosensitive resin, characterized in that, Comprising the following raw materials by mass parts: 10 - 25 parts of blocked diisocyanate, 30 - 70 parts of acrylic modified polyamine, 20 - 40 parts of reactive diluent, 2 - 5 parts of photoinitiator; The structural formula of the said blocked diisocyanate is shown as Formula Ⅰ: Formula Ⅰ; The structural formula of the said acrylic modified polyamine is shown as Formula Ⅱ: Formula II; In Formula Ⅱ, n1 = 1~20, n2 = 1~20, n3 = 1~20.

2. The one-component 3D printing photosensitive resin according to claim 1, wherein The said reactive diluent is 2 - methyl - 1,3 - propanediol diacrylate.

3. The one-component 3D printing photosensitive resin according to claim 1, wherein The said photoinitiator is diphenyl(2,4,6 - trimethylbenzoyl)phosphine oxide.

4. The preparation method of the one-component 3D printing photosensitive resin according to claim 1, wherein, Comprising: Step 1: Add hexamethylene diisocyanate, phenol, catalyst and solvent into a reaction vessel, carry out the reaction to obtain the blocked diisocyanate shown as Formula Ⅰ; Formula Ⅰ; Step 2: Dissolve methacrylic acid and hydroquinone in a solvent to obtain a monomer solution. Under nitrogen protection, add a ternary amine containing a flexible aliphatic chain structure and a catalyst into the reaction vessel. After cooling the reaction system to 0~5℃ in an ice - water bath, drop the above monomer solution into the reaction vessel. After the dropping is completed, let the reaction system naturally warm up to room temperature and continue the reaction for 4~6 hours. After post - treatment, obtain the acrylic modified polyamine shown as Formula Ⅱ; Formula II; In Formula Ⅱ, n1 = 1~20, n2 = 1~20, n3 = 1~20; Step 3: Mix the blocked diisocyanate prepared in Step 1, the acrylic modified polyamine prepared in Step 2, the reactive diluent and the photoinitiator to obtain a one - component 3D printing photosensitive resin.

5. The preparation method of the one-component 3D printing photosensitive resin according to claim 4, characterized in that, The molar ratio of hexamethylene diisocyanate to phenol in the said Step 1 is 1:(2~2.2).

6. The preparation method of the one-component 3D printing photosensitive resin according to claim 4, characterized in that, The reaction temperature of the said Step 1 is 60~80℃, and the reaction time is 2~4 hours.

7. The preparation method of the one-component 3D printing photosensitive resin according to claim 4, characterized in that The molar ratio of the ternary amine containing a flexible aliphatic chain structure to methacrylic acid in the said Step 2 is 1:(1~1.2).

8. An elastomeric material, comprising the one - component 3D printing photosensitive resin described in Claim 1.

9. The preparation method of an elastomeric material according to claim 8, characterized in that, Comprising: Step 1: Place the one - component 3D printing photosensitive resin in the resin tank of a 3D printer, carry out photocuring to obtain a photocured product; Step 2: Carry out thermal curing on the photocured product obtained in Step 1 to obtain an elastomeric material.

10. The preparation method of an elastomeric material according to claim 9, wherein, The thermal curing in the said Step 2 is to preheat in an oven at 80~100℃ for 0.5~2 hours first, and then raise the temperature to 120~150℃ and keep it for 1~2 hours.

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