Photosensitive resin for 3D printing and preparation method thereof

Abstract

The invention discloses photosensitive resin for 3D printing and a preparation method thereof, and relates to the technical field of organic materials. The invention discloses a preparation method of photosensitive resin for 3D printing, which comprises the following steps: blending an epoxy acrylate prepolymer, an additive, a reactive diluent and a photoinitiator according to the raw material ratio of the photosensitive resin to obtain the photosensitive resin; wherein the additive is prepared by the following steps: carrying out a reaction on polytetrahydrofuran ether glycol, isophorone diisocyanate and 2, 2-bis (hydroxymethyl) propionic acid to prepare a polyurethane prepolymer, crosslinking the polyurethane prepolymer with aminated nano aluminum oxide, and finally carrying out a reaction with hydroxyethyl acrylate; the prepared additive is added into photosensitive resin, and the problems that existing epoxy acrylate type photosensitive resin is insufficient in flexibility and large in brittleness, and the bonding strength between low-surface-energy materials is small are effectively solved. The photosensitive resin prepared in the invention has excellent mechanical properties and high bonding strength, and the prepared product has excellent and stable quality.

Description

Technical Field

[0001] The present invention relates to the technical field of organic materials, and particularly relates to a photosensitive resin for 3D printing and a preparation method thereof. Background Art

[0002] 3D printing technology, also known as three-dimensional manufacturing technology or rapid prototyping (RP), is a technology that uses a computer program based on three-dimensional image information and uses materials that can be bonded to manufacture products by layer-by-layer printing of a designed three-dimensional model. Compared with traditional subtractive manufacturing technologies such as cutting and forging, the principle of 3D printing is the discretization and accumulation of materials and the layer-by-layer processing of a digitally formed model. 3D printing does not require the production of a physical model and can obtain an accurate model only relying on a three-dimensional stereoscopic image, greatly reducing the time for manufacturing the model. Moreover, 3D printing models have high precision, no scrap, are environmentally friendly and have low development costs. It is widely used in the manufacture of large parts, casting of complex shapes, etc. Currently, 3D printing can be mainly divided into four categories according to different printing materials: stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and bio-three-dimensional printing.

[0003] Stereolithography (SLA) is an additive manufacturing technology based on photosensitive materials, and it is a manufacturing technology that forms a product through processes such as rapid curing, heating, grinding, spraying, and surface treatment of photosensitive resin. The advantages of stereolithography (SLA) compared with other 3D printing technologies are mainly manifested in: (1) High resolution: The use of ultraviolet light beams can make the resin form pixels at the millimeter level, so very high resolution can be achieved; (2) High manufacturing speed: Using ultraviolet irradiation for curing, the printing speed is faster; (3) Wide application range: Whether it is small parts or complex industrial products, stereolithography 3D printing technology can be used for manufacturing. There are many types of photosensitive resins used for stereolithography (SLA), and its main components are: diluent, photoinitiator, prepolymer, and auxiliary additives, etc. According to the different prepolymers, photosensitive resins can be further divided into epoxy acrylate resin, unsaturated polyester, polyester acrylate, and polyurethane acrylate. Among them, epoxy acrylate resin is the most widely used type of photocuring resin in the curing field, with good adhesion, high bonding strength, fast curing speed, good chemical resistance, and low price. However, epoxy acrylate resin has problems such as insufficient flexibility, high brittleness, and low bonding strength between low surface energy materials, which limit its wider application in stereolithography 3D printing technology. Summary of the Invention

[0004] The purpose of the present invention is to provide a photosensitive resin for 3D printing and a preparation method thereof, to solve the following technical problems: When existing epoxy acrylate resins are applied in photocuring 3D printing technology, there are problems such as insufficient flexibility, high brittleness, and low bonding strength between low surface energy materials.

[0005] The object of the present invention can be achieved through the following technical solutions: A preparation method of a photosensitive resin for 3D printing, comprising the following steps: according to the raw material ratio of the photosensitive resin, blend the epoxy acrylate prepolymer and the additive, and then sequentially add the reactive diluent and the photoinitiator for blending to obtain the photosensitive resin; The preparation method of the additive comprises the following steps: In a nitrogen atmosphere, add polytetrahydrofuran ether glycol and isophorone diisocyanate into a reaction kettle and disperse evenly, control the temperature at 80 - 90 °C, keep the temperature for reaction for 1 - 3 h, control the temperature at 70 - 80 °C, blend 2,2 - bis(hydroxymethyl)propionic acid and N - methylpyrrolidone and then add them into the reaction kettle, keep the temperature for reaction for 2 - 4 h, add 1,4 - butanediol, keep the temperature for reaction for 1 - 2 h, control the temperature at 85 - 95 °C, add amino - functionalized nano - alumina, keep the temperature for reaction for 1 - 3 h, control the temperature at 50 - 60 °C, add hydroxyethyl acrylate, dibutyltin dilaurate, and hydroquinone, keep the temperature for reaction for 2 - 4 h to obtain the additive.

[0006] As a further scheme of the present invention: the addition ratios of polytetrahydrofuran ether glycol, isophorone diisocyanate, 2,2 - bis(hydroxymethyl)propionic acid, N - methylpyrrolidone, 1,4 - butanediol, amino - functionalized nano - alumina, hydroxyethyl acrylate, dibutyltin dilaurate, and hydroquinone are 100 g: 35 - 45 g: 20 - 30 g: 100 - 200 mL: 8 - 12 g: 15 - 30 g: 30 - 50 g: 0.2 - 0.6 g: 0.05 - 0.1 g.

[0007] As a further scheme of the present invention: the preparation method of the amino - functionalized nano - alumina comprises the following steps: In a nitrogen atmosphere, add γ - aminopropyltriethoxysilane, absolute ethanol, and deionized water into a reaction kettle for blending, adjust the pH to 3 - 4, stir and dissolve at room temperature for 0.5 - 1.5 h, add nano - alumina, control the temperature at 40 - 50 °C, keep the temperature for reaction for 4 - 8 h under stirring conditions, let it stand, take the precipitate for washing and drying to obtain the amino - functionalized nano - alumina.

[0008] As a further scheme of the present invention: the addition ratios of γ - aminopropyltriethoxysilane, absolute ethanol, deionized water, and nano - alumina are 20 - 30 mL: 180 - 450 mL: 20 - 50 mL: 10 g.

[0009] As a further scheme of the present invention: the preparation method of the epoxy acrylate prepolymer comprises the following steps: Add epoxy resin into the reaction kettle, control the temperature at 85 - 95 °C, blend triphenylphosphine, hydroquinone, and acrylic acid and then add them into the reaction kettle, control the temperature at 90 - 100 °C, keep the temperature for reaction for 1 - 1.5 h to obtain an epoxy acrylate prepolymer.

[0010] As a further scheme of the present invention: the addition ratio of epoxy resin, triphenylphosphine, hydroquinone, and acrylic acid is 100 g: 0.6 - 1.5 g: 0.003 - 0.006 g: 10 - 11 g.

[0011] As a further scheme of the present invention: the photosensitive resin comprises raw materials in the following weight percentages: 40 - 50% epoxy acrylate prepolymer, 3 - 8% photoinitiator, 5 - 15% active diluent, 30 - 35% additive, and the sum of the weight percentages of the raw materials is 100%.

[0012] As a further scheme of the present invention: the diluent is any one of bifunctional diluents and polyfunctional diluents.

[0013] As a further scheme of the present invention: the bifunctional diluent is any one of dipropylene glycol diacrylate, dipropylene glycol - type diacrylate, and 1,6 - hexanediol diacrylate; As a further scheme of the present invention: the polyfunctional diluent is trimethylolpropane triacrylate or dipentaerythritol pentaacrylate.

[0014] As a further scheme of the present invention: the photoinitiator is one or two of cationic photoinitiators and free - radical photoinitiators mixed in any ratio.

[0015] As a further scheme of the present invention: the cationic photoinitiator is any one or several of diaryliodonium salts, triarylsulfonium salts, and aromatic ferrocenium salts mixed in any ratio.

[0016] As a further scheme of the present invention: the free - radical photoinitiator is a cleavage - type free - radical photoinitiator and a hydrogen - abstracting free - radical photoinitiator; the cleavage - type free - radical photoinitiator is any one or several of α,α - dimethoxybenzil ketal, 2 - methyl - 1 - (4 - methylthiophenyl) - 2 - morpholinopropan - 1 - one, 1 - hydroxycyclohexyl phenyl ketone, and 2,4,6 - trimethylbenzoyl diphenylphosphine oxide mixed in any ratio; the hydrogen - abstracting free - radical photoinitiator is any one or several of benzophenone, isopropylthioxanthone, and ethyl N,N - dimethylbenzoate mixed in any ratio.

[0017] A photosensitive resin for 3D printing is prepared by the preparation method of any one of the above.

[0018] The beneficial effects of the present invention: (1) First, the present application uses γ-aminopropyltriethoxysilane to organically modify nano-aluminum oxide to obtain amino-functionalized nano-aluminum oxide. The present application uses polytetrahydrofuran ether glycol and isophorone diisocyanate as raw materials, and uses 2,2-bis(hydroxymethyl)propionic acid as a hydrophilic chain extender and 1,4-butanediol as a small molecule chain extender to prepare a polyurethane prepolymer; then uses the amino group of the amino-functionalized nano-aluminum oxide to react with the carboxyl group of the polyurethane prepolymer to obtain a polyurethane prepolymer grafted with nano-aluminum oxide; then uses hydroxyethyl acrylate to react with the remaining isocyanate groups of the polyurethane prepolymer grafted with nano-aluminum oxide to prepare an additive. The additive molecule chain in the present application is grafted with amino-functionalized nano-aluminum oxide, effectively improving the thermal stability and adhesion of the material. The introduction of amino-functionalized nano-aluminum oxide reacts with the carboxyl group of the polyurethane prepolymer through the amino group on the surface, and physical anchoring and chemical action enhance the interfacial bonding.

[0019] The present application uses epoxy resin and acrylic acid to obtain epoxy acrylate through an esterification reaction. The present application uses epoxy acrylate as a prepolymer, and adds an additive, a reactive diluent, and a photoinitiator to prepare a photosensitive resin. The photosensitive resin prepared in the present application effectively reduces the shrinkage warping of the photosensitive resin and improves the flexibility of the material by adding an additive containing a long-chain soft segment, and improves the precision and mechanical properties of the photocured product. After the photosensitive resin prepared in the present application is irradiated with light, the resin can quickly complete curing, and the cured resin has high tensile strength, bending strength, toughness, and good thermal stability; the photoinitiator in the present application initiates the reaction of the photosensitive resin system, and the whole system forms an interpenetrating network structure, thereby improving the mechanical properties of the workpiece.

[0020] The additive prepared in the present application is blended with epoxy acrylate to prepare a photosensitive resin.

[0021] The additive prepared in the present application has a flexible chain segment and inorganic particles. The amino-functionalized nano-aluminum oxide is connected to the additive molecule chain through a chemical bond, which not only improves the flexibility but also enhances the interfacial adhesion. At the same time, the addition of amino-functionalized nano-aluminum oxide does not involve double bond reactions and does not cause volume shrinkage; it effectively alleviates the trend of volume shrinkage and poor toughness of the product.

[0022] The photosensitive resin designed in the present application has an interpenetrating network structure, and its three-dimensional branched structure can disperse stress, while reducing the viscosity of the system and improving the printing fluidity. After the photosensitive resin prepared in the present application forms a primary network by photocuring, thermal crosslinking is carried out through the unreacted groups to enhance the interfacial chemical bond density.

[0023] The photosensitive resin prepared in the present application has a low shrinkage rate, which can effectively improve the precision of the forming process, greatly reduce the occurrence probability of specimen deformation and cracking, and effectively avoid warping of the product during the forming process, ensuring the forming of the product. Specific Embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1 The preparation method of the additive includes the following steps: A1: In a nitrogen atmosphere, 20 mL of γ-aminopropyltriethoxysilane, 180 mL of absolute ethanol, and 20 mL of deionized water are added to a reaction kettle for blending. 10 wt% citric acid aqueous solution is added to adjust the pH to 3, and stirred and dissolved at room temperature for 0.5 h. 10 g of nano-aluminum oxide is added, the temperature is controlled at 40 °C, and the reaction is carried out under stirring conditions for 4 h. After standing, the precipitate is taken out, washed, and dried to obtain amino-functionalized nano-aluminum oxide. A2: In a nitrogen atmosphere, 100 g of polytetrahydrofuran ether diol (PTMEG, number average molecular weight 1000) and 35 g of isophorone diisocyanate are added to a reaction kettle and dispersed evenly. The temperature is controlled at 80 °C, and the reaction is carried out under heat preservation for 1 h. The temperature is controlled at 70 °C, 20 g of 2,2-bis(hydroxymethyl)propionic acid and 100 mL of N-methylpyrrolidone are blended and then added to the reaction kettle, and the reaction is carried out under heat preservation for 2 h. 8 g of 1,4-butanediol is added, and the reaction is carried out under heat preservation for 1 h. The temperature is controlled at 85 °C, 15 g of amino-functionalized nano-aluminum oxide is added, and the reaction is carried out under heat preservation for 1 h. The temperature is controlled at 50 °C, 30 g of hydroxyethyl acrylate, 0.2 g of dibutyltin dilaurate, and 0.05 g of hydroquinone are added, and the reaction is carried out under heat preservation for 2 h to obtain the additive.

[0026] The preparation method of the epoxy acrylate prepolymer includes the following steps: 100 g of epoxy resin (bisphenol F epoxy resin 830S) is added to a reaction kettle, the temperature is controlled at 85 °C, 0.6 g of triphenylphosphine, 0.003 g of hydroquinone, and 10 g of acrylic acid are blended and then added to the reaction kettle, the temperature is controlled at 90 °C, and the reaction is carried out under heat preservation for 1 h to obtain the epoxy acrylate prepolymer.

[0027] Example 2 The preparation method of the additive includes the following steps: A1: In a nitrogen atmosphere, 25 mL of γ-aminopropyltriethoxysilane, 350 mL of absolute ethanol, and 35 mL of deionized water are added to a reaction kettle for blending. 10 wt% citric acid aqueous solution is added to adjust the pH to 3, and stirred and dissolved at room temperature for 1 h. 10 g of nano-aluminum oxide is added, the temperature is controlled at 45 °C, and the reaction is carried out under stirring conditions for 6 h. After standing, the precipitate is taken out, washed, and dried to obtain amino-functionalized nano-aluminum oxide. A2: In a nitrogen atmosphere, 100 g of polytetrahydrofuran ether diol (PTMEG, number-average molecular weight 1000) and 40 g of isophorone diisocyanate were added to a reaction kettle and dispersed evenly. The temperature was controlled at 85 °C and the reaction was carried out with heat preservation for 2 h. Then the temperature was controlled at 75 °C. 25 g of 2,2-bis(hydroxymethyl)propionic acid and 150 mL of N-methylpyrrolidone were blended and then added to the reaction kettle. The reaction was carried out with heat preservation for 3 h. 10 g of 1,4-butanediol was added and the reaction was carried out with heat preservation for 1.5 h. The temperature was controlled at 90 °C, 22 g of amino-functionalized nano-alumina was added, and the reaction was carried out with heat preservation for 2 h. The temperature was controlled at 55 °C, 40 g of hydroxyethyl acrylate, 0.4 g of dibutyltin dilaurate, and 0.07 g of hydroquinone were added, and the reaction was carried out with heat preservation for 3 h to obtain the additive.

[0028] The preparation method of the epoxy acrylate prepolymer comprises the following steps: 100 g of epoxy resin (bisphenol F epoxy resin 830S) was added to a reaction kettle. The temperature was controlled at 90 °C. 1 g of triphenylphosphine, 0.004 g of hydroquinone, and 10.5 g of acrylic acid were blended and then added to the reaction kettle. The temperature was controlled at 95 °C and the reaction was carried out with heat preservation for 1.5 h to obtain the epoxy acrylate prepolymer.

[0029] Example 3 The preparation method of the additive comprises the following steps: A1: In a nitrogen atmosphere, 30 mL of γ-aminopropyltriethoxysilane, 450 mL of absolute ethanol, and 50 mL of deionized water were added to a reaction kettle and blended. 10 wt% citric acid aqueous solution was added to adjust the pH to 3. Stirring and dissolving were carried out at room temperature for 1.5 h. 10 g of nano-alumina was added. The temperature was controlled at 50 °C and the reaction was carried out with heat preservation for 8 h under stirring conditions. The precipitate was allowed to stand, washed, and dried to obtain amino-functionalized nano-alumina; A2: In a nitrogen atmosphere, 100 g of polytetrahydrofuran ether diol (PTMEG, number-average molecular weight 1000) and 45 g of isophorone diisocyanate were added to a reaction kettle and dispersed evenly. The temperature was controlled at 90 °C and the reaction was carried out with heat preservation for 3 h. Then the temperature was controlled at 80 °C. 30 g of 2,2-bis(hydroxymethyl)propionic acid and 200 mL of N-methylpyrrolidone were blended and then added to the reaction kettle. The reaction was carried out with heat preservation for 2 - 4 h. 12 g of 1,4-butanediol was added and the reaction was carried out with heat preservation for 2 h. The temperature was controlled at 95 °C, 30 g of amino-functionalized nano-alumina was added, and the reaction was carried out with heat preservation for 1 - 3 h. The temperature was controlled at 60 °C, 50 g of hydroxyethyl acrylate, 0.6 g of dibutyltin dilaurate, and 0.1 g of hydroquinone were added, and the reaction was carried out with heat preservation for 4 h to obtain the additive.

[0030] The preparation method of the epoxy acrylate prepolymer comprises the following steps: Add 100 g of epoxy resin (bisphenol F epoxy resin 830S) to the reaction kettle, control the temperature at 95 °C, blend 1.5 g of triphenylphosphine, 0.006 g of hydroquinone, and 11 g of acrylic acid, then add them to the reaction kettle, control the temperature at 100 °C, and keep the temperature for reaction for 1.5 h to obtain an epoxy acrylate prepolymer.

[0031] Example 4 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Example 1 and 34 g of the additive prepared in Example 1, then successively add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend them to obtain a photosensitive resin.

[0032] Example 5 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Example 2 and 34 g of the additive prepared in Example 2, then successively add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend them to obtain a photosensitive resin.

[0033] Example 6 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Example 3 and 34 g of the additive prepared in Example 3, then successively add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend them to obtain a photosensitive resin.

[0034] Comparative Example 1 The preparation method of the additive comprises the following steps: A1: In a nitrogen atmosphere, add 25 mL of γ-aminopropyltriethoxysilane, 350 mL of absolute ethanol, and 35 mL of deionized water to the reaction kettle and blend them. Add a 10 wt% citric acid aqueous solution to adjust the pH to 3, stir and dissolve at room temperature for 1 h, add 10 g of nano-aluminum oxide, control the temperature at 45 °C, keep the temperature for reaction for 6 h under stirring conditions, let it stand, take the precipitate, wash and dry it to obtain amino-functionalized nano-aluminum oxide; A2: In a nitrogen atmosphere, disperse 100 g of polytetrahydrofuran ether glycol (PTMEG, number average molecular weight 1000) and 40 g of isophorone diisocyanate in the reaction kettle, control the temperature at 85 °C, keep the temperature for reaction for 2 h, control the temperature at 75 °C, blend 25 g of 2,2-bis(hydroxymethyl)propionic acid and 150 mL of N-methylpyrrolidone and add them to the reaction kettle, keep the temperature for reaction for 3 h, add 10 g of 1,4-butanediol, keep the temperature for reaction for 1.5 h, control the temperature at 90 °C, add 22 g of amino-functionalized nano-aluminum oxide, and keep the temperature for reaction for 2 h to obtain the additive.

[0035] The preparation method of the epoxy acrylate prepolymer comprises the following steps: Add 100 g of epoxy resin (bisphenol F epoxy resin 830S) into the reaction kettle, control the temperature at 90 °C, blend 1 g of triphenylphosphine, 0.004 g of hydroquinone, and 10.5 g of acrylic acid and then add them into the reaction kettle, control the temperature at 95 °C, keep the temperature for reaction for 1.5 h to obtain the epoxy acrylate prepolymer.

[0036] Comparative Example 2 The preparation method of the additive comprises the following steps: A1: In a nitrogen atmosphere, add 25 mL of γ-aminopropyltriethoxysilane, 350 mL of absolute ethanol, and 35 mL of deionized water into the reaction kettle for blending, add 10 wt% citric acid aqueous solution to adjust the pH to 3, stir and dissolve at room temperature for 1 h, add 10 g of nano-aluminum oxide, control the temperature at 45 °C, keep the temperature for reaction for 6 h under stirring, let it stand, take the precipitate for washing and drying to obtain amino-functionalized nano-aluminum oxide; A2: In a nitrogen atmosphere, add 100 g of polytetrahydrofuran ether glycol (PTMEG, number average molecular weight 1000) and 40 g of isophorone diisocyanate into the reaction kettle for uniform dispersion, control the temperature at 85 °C, keep the temperature for reaction for 2 h, control the temperature at 55 °C, add 40 g of hydroxyethyl acrylate, 0.4 g of dibutyltin dilaurate, and 0.07 g of hydroquinone, keep the temperature for reaction for 3 h, add 22 g of amino-functionalized nano-aluminum oxide for uniform dispersion to obtain the additive.

[0037] The preparation method of the epoxy acrylate prepolymer comprises the following steps: Add 100 g of epoxy resin (bisphenol F epoxy resin 830S) into the reaction kettle, control the temperature at 90 °C, blend 1 g of triphenylphosphine, 0.004 g of hydroquinone, and 10.5 g of acrylic acid and then add them into the reaction kettle, control the temperature at 95 °C, keep the temperature for reaction for 1.5 h to obtain the epoxy acrylate prepolymer.

[0038] Comparative Example 3 The preparation method of the additive comprises the following steps: A2: In a nitrogen atmosphere, add 100 g of polytetrahydrofuran ether glycol (PTMEG, number average molecular weight 1000) and 40 g of isophorone diisocyanate into the reaction kettle for uniform dispersion, control the temperature at 85 °C, keep the temperature for reaction for 2 h, control the temperature at 55 °C, add 40 g of hydroxyethyl acrylate, 0.4 g of dibutyltin dilaurate, and 0.07 g of hydroquinone, keep the temperature for reaction for 3 h to obtain the additive.

[0039] The preparation method of the epoxy acrylate prepolymer comprises the following steps: Add 100 g of epoxy resin (bisphenol F epoxy resin 830S) to the reaction kettle, control the temperature at 90 °C, blend 1 g of triphenylphosphine, 0.004 g of hydroquinone, and 10.5 g of acrylic acid, then add the blend to the reaction kettle, control the temperature at 95 °C, and keep the temperature for 1.5 h to obtain the epoxy acrylate prepolymer.

[0040] Comparative Example 4 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Comparative Example 1 and 34 g of the additive prepared in Comparative Example 1, then sequentially add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend to obtain the photosensitive resin.

[0041] Comparative Example 5 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Comparative Example 2 and 34 g of the additive prepared in Comparative Example 2, then sequentially add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend to obtain the photosensitive resin.

[0042] Comparative Example 6 A method for preparing a photosensitive resin for 3D printing, comprising the following steps: Blend 48 g of the epoxy acrylate prepolymer prepared in Comparative Example 3 and 34 g of the additive prepared in Comparative Example 3, then sequentially add 3.5 g of triarylsulfonium salt, 2.5 g of α,α-dimethoxybenzil ketal, and 12 g of trimethylolpropane triacrylate and blend to obtain the photosensitive resin.

[0043] Performance testing (1) Shrinkage rate: ① Use the pycnometer method and calculate the density ρ1 of the photosensitive resin liquid before curing according to the following formula: ρ1 = [(m2 - m0) / (m1 - m0)] × ρ0; In the formula, ρ1 - density of the photosensitive resin liquid before curing, g / cm 3 ; m0 - mass of the pycnometer, g; m1 - mass of the pycnometer plus water, g; m2 - total mass of the pycnometer filled with resin, g; ρ0 - density of water, g / cm 3 ; ② Use the suspension buoyancy method to measure the volume V of the photosensitive resin after curing, and weigh the mass and record it as m1. Calculate the density ρ2 of the photosensitive resin after curing according to the following formula: V = (m1 + m2 - m3) / ρ0; ρ2 = m2 / V; In the formula, V - solid volume of the photosensitive resin after curing, cm3 ; m1 - Total mass of water and beaker, g; m2 - Mass of photosensitive resin, g; m3 - Total mass after placing photosensitive resin, g; ρ0 - Water density, g / cm 3 ; ρ2 - Density of cured photosensitive resin, g / cm 3 ; ③Shrinkage rate η η = [(ρ2 - ρ1) / ρ2] × 100%; In the formula, ρ1 - Density of liquid photosensitive resin before curing, g / cm 3 ; ρ2 - Density of cured photosensitive resin, g / cm 3 ; The calculation results are shown in Table 1; (2)Gel content: Weigh the mass of the cured epoxy resin as m1, put it into a Soxhlet extractor and dissolve it with acetone. After 12 h, dry it in a forced-air drying oven at 60 °C for 2 h, and weigh it as m2. Calculate the gel content according to the following formula: Gel content = [(m2 - m1) / m2] × 100%; In the formula, m1 - Mass of resin before extraction, g; m2 - Mass of resin after extraction, g; The calculation results are shown in Table 1; Table 1: Statistical table of physical and chemical property test data of Examples 4 - 6 and Comparative Examples 4 - 6

[0044] As can be seen from Table 1, the photosensitive resin prepared in this application has a low shrinkage rate and gel content. After the photosensitive resin prepared in this application is irradiated by light, the resin can be quickly cured, and the precision of the photocured product is high.

[0045] (3)Tensile strength: Detect according to GB / T 1040.1 - 2008, tensile speed 10 mm / min, and the test results are shown in Table 2; (4)Flexural strength: Detect according to GB / T 9341 - 2008, flexural speed 5 mm / min, and the test results are shown in Table 2; (5)Impact strength: Print and form a notched specimen according to GB / T 1843 - 2008, and calculate the impact strength σ according to the following formula: σ = W / (hb); In the formula, σ - Izod notched impact strength, kJ / m 2 ; W - Impact energy absorbed by the specimen, J; h - Thickness of the specimen, mm; b - Remaining width of the specimen, mm; The test results are shown in Table 2; (5)Shore hardness: Detect according to GB / T 2411 - 2008, and the test results are shown in Table 2; Table 2: Statistical table of mechanical property test data of Examples 4 - 6 and Comparative Examples 4 - 6

[0046] As can be seen from Table 2, the photosensitive resin prepared in this application has the characteristics of high toughness and good mechanical properties after curing.

[0047] The above has described a specific embodiment of the present invention in detail, but the described content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A preparation method of a photosensitive resin for 3D printing, characterized in that, It includes the following steps: According to the raw material ratio of the photosensitive resin, blend the epoxy acrylate prepolymer and the additive, and then successively add the reactive diluent and the photoinitiator and blend them to obtain the photosensitive resin. The preparation method of the additive includes the following steps: In a nitrogen atmosphere, add polytetrahydrofuran ether diol and isophorone diisocyanate into the reaction kettle and disperse them evenly. Control the temperature at 80 - 90 °C and keep the temperature for 1 - 3 h. Then control the temperature at 70 - 80 °C, blend 2,2 - bis(hydroxymethyl)propionic acid and N - methylpyrrolidone and add them into the reaction kettle, keep the temperature for 2 - 4 h, add 1,4 - butanediol, keep the temperature for 1 - 2 h, control the temperature at 85 - 95 °C, add amino - functionalized nano - alumina, keep the temperature for 1 - 3 h, control the temperature at 50 - 60 °C, add hydroxyethyl acrylate, dibutyltin dilaurate, and hydroquinone, and keep the temperature for 2 - 4 h to obtain the additive.

2. The preparation method of a photosensitive resin for 3D printing according to claim 1, characterized in that, The addition ratio of polytetrahydrofuran ether diol, isophorone diisocyanate, 2,2 - bis(hydroxymethyl)propionic acid, N - methylpyrrolidone, 1,4 - butanediol, amino - functionalized nano - alumina, hydroxyethyl acrylate, dibutyltin dilaurate, and hydroquinone is 100 g : 35 - 45 g : 20 - 30 g : 100 - 200 mL : 8 - 12 g : 15 - 30 g : 30 - 50 g : 0.2 - 0.6 g : 0.05 - 0.1 g.

3. The preparation method of a photosensitive resin for 3D printing according to claim 1, characterized in that, The preparation method of the amino - functionalized nano - alumina includes the following steps: In a nitrogen atmosphere, add γ - aminopropyltriethoxysilane, absolute ethanol, and deionized water into the reaction kettle and blend them. Adjust the pH to 3 - 4, stir and dissolve at room temperature for 0.5 - 1.5 h, add nano - alumina, control the temperature at 40 - 50 °C, keep the temperature under stirring for 4 - 8 h, let it stand, take the precipitate, wash and dry it to obtain the amino - functionalized nano - alumina.

4. The preparation method of a photosensitive resin for 3D printing according to claim 3, characterized in that, The addition ratio of γ - aminopropyltriethoxysilane, absolute ethanol, deionized water, and nano - alumina is 20 - 30 mL : 180 - 450 mL : 20 - 50 mL : 10 g.

5. The preparation method of a photosensitive resin for 3D printing according to claim 1, wherein, The preparation method of the epoxy acrylate prepolymer includes the following steps: Add epoxy resin into the reaction kettle, control the temperature at 85 - 95 °C, blend triphenylphosphine, hydroquinone, and acrylic acid and add them into the reaction kettle, control the temperature at 90 - 100 °C, keep the temperature for 1 - 1.5 h to obtain the epoxy acrylate prepolymer.

6. The preparation method of a photosensitive resin for 3D printing according to claim 5, wherein, The addition ratio of epoxy resin, triphenylphosphine, hydroquinone, and acrylic acid is 100 g : 0.6 - 1.5 g : 0.003 - 0.006 g : 10 - 11 g.

7. The preparation method of a photosensitive resin for 3D printing according to claim 1, characterized in that, The photosensitive resin includes the following raw materials by weight percentage: 40 - 50% epoxy acrylate prepolymer, 3 - 8% photoinitiator, 5 - 15% reactive diluent, 30 - 35% additive, and the sum of the weight percentages of the raw materials is 100%.

8. The preparation method of a photosensitive resin for 3D printing according to claim 1, wherein, The diluent is any one of bifunctional diluents and polyfunctional diluents.

9. The preparation method of a photosensitive resin for 3D printing according to claim 1, characterized in that The photoinitiator is one or a mixture of two of cationic photoinitiators and free - radical photoinitiators in any ratio.

10. A photosensitive resin for 3D printing, characterized in that, It is made by the preparation method described in any one of claims 1 - 9.

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