Washable bio-based photosensitive resin for 3D printing and preparation method thereof

Abstract

The invention discloses washable bio-based photosensitive resin for 3D printing and a preparation method of the washable bio-based photosensitive resin. The washable bio-based photosensitive resin for 3D printing is prepared from the following raw material components: 11.5%-25.5% of bio-based polyol, 5.4%-8.4% of a side chain type nonionic hydrophilic chain extender, 4.0%-8.3% of isocyanate, 0.06%-0.13% of a catalyst, 56.7%-76.1% of a hydroxyl acrylate monomer and 1.0%-2.9% of a photoinitiator, the long side chain type nonionic hydrophilic chain extender is used for providing the photosensitive resin with good flexibility and hydrophilicity, so that the polyurethane acrylate photosensitive resin has excellent elongation at break and water solubility. In addition, the polyurethane acrylate photosensitive resin prepared by using the bio-based polyol to replace a petroleum-based material is more in line with green and environment-friendly requirements.

Description

Technical Field

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

[0002] Stereolithography 3D printing technology is an advanced additive manufacturing technology that constructs three-dimensional objects layer by layer by utilizing the properties of photosensitive resin materials. During the printing process, ultraviolet light or other light sources are precisely irradiated on the liquid photosensitive resin, triggering a polymerization reaction that rapidly transforms it from a liquid to a solid state, thereby achieving the layer-by-layer curing and shaping of the object. This technology not only features high precision and high efficiency but also can fabricate complex geometric shapes, and is widely applied in multiple fields such as industrial design, medical treatment, aerospace, and cultural and creative industries.

[0003] The photosensitive resin material for 3D printing is a core component of stereolithography technology. Traditional photosensitive resins are mainly oil-based resins. After printing, such resins usually require the use of organic solvents such as alcohol to clean the surface of the printed product to remove the residual resin. However, the use of organic solvents not only increases costs but may also pose hazards to the environment. Organic solvents are highly volatile, and their volatiles can pollute the air. At the same time, they may also have an adverse impact on the health of operators during use and handling. In addition, the recovery and treatment of organic solvents require additional equipment and cost inputs, which to a certain extent limit the large-scale application of stereolithography 3D printing technology.

[0004] Therefore, in recent years, researchers and enterprises have begun to focus on developing new photosensitive resin materials to replace traditional oil-based resins. For example, the emergence of water-based photosensitive resins provides a new idea for solving these problems. Hydrophilic resins have good water solubility, and the residual resin on the surface of the product after 3D printing can be directly washed with water, achieving the dissolution of the uncured part and the purpose of being water-washable. Moreover, this process does not use organic solvents for cleaning, does not produce toxic waste liquid, can reduce environmental pollution and operation risks, and meets the requirements of environmental protection. For example, Chinese Patent CN116731282A prepared a water-washable 3D printing resin using organosilicon resin prepolymers, etc. The resin has good water-washing performance and the printed product is easy to clean, but the elongation at break of this resin is relatively low. Using a water-washable photosensitive resin with both good hydrophilicity and mechanical properties for 3D printing is one of the development directions of stereolithography 3D printing technology.

[0005] At present, most of the raw materials for synthesizing water-washable photocurable resins are derived from fossil raw materials such as petroleum, which are non-renewable. For example, Chinese Patent CN114573761A reports a preparation method of a polyurethane acrylate photosensitive resin. This method endows the photosensitive resin with good water-washable performance by introducing structures such as sulfonates, but the polymer polyol used in this material comes from traditional petroleum-based raw materials. Chinese Patent CN116003734A reports a preparation method of an aqueous polyester acrylate that can be applied to water-washable photocurable 3D printing. This method uses N,N-dimethylethanolamine as a hydrophilic group to prepare a cationic aqueous resin, which has good hydrophilicity and printing performance, but this method also uses non-renewable petroleum-based raw materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a water-washable bio-based photosensitive resin for 3D printing and its preparation method to solve the following technical problems:

[0007] How to improve the hydrophilicity and mechanical properties of the 3D printing photosensitive resin and meet the requirements of green environmental protection.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A water-washable bio-based photosensitive resin for 3D printing, calculated by mass fraction, the preparation raw materials include the following components:

[0010] Bio-based polyol 11.5%-25.5%;

[0011] Side-chain non-ionic hydrophilic chain extender 5.4%-8.4%;

[0012] Isocyanate 4.0%-8.3%;

[0013] Catalyst 0.06%-0.13%;

[0014] Hydroxy acrylate monomer 56.7%-76.1%;

[0015] Photoinitiator 1.0%-2.9%.

[0016] Preferably, the bio-based polyol includes one of modified castor oil polyol D2000, bio-based polytrimethylene ether glycol, cashew shell oil polyol or soybean oil polyol, and the molecular weight is 1000-2000.

[0017] Preferably, the side-chain non-ionic hydrophilic chain extender is product Ymer N120 of Perstorp Company.

[0018] Preferably, the isocyanate is one of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), or tetramethylxylylene diisocyanate (TMXDI).

[0019] Preferably, the catalyst is an organic bismuth catalyst MC-710.

[0020] Preferably, the hydroxyacrylate monomer is one of 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), or 2-hydroxyethyl acrylate (HEA).

[0021] Preferably, the photoinitiator is one of 2,4,6-trimethylbenzoyl-dimethylphenylphosphine oxide (TMO), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (819).

[0022] The present invention provides a preparation method of a water-washable bio-based photosensitive resin for 3D printing, comprising the following steps:

[0023] S1. Heat the bio-based polyol and the side-chain nonionic hydrophilic chain extender, then dehydrate them under vacuum. After cooling, add the isocyanate and the catalyst for mixing, and then heat and stir the reaction again to obtain a first mixture.

[0024] S2. Cool down to 60°C, mix the first mixture with the hydroxyacrylate monomer, heat up to 85°C and continue stirring and reacting for 0.5 h to obtain a second mixture.

[0025] S3. After the reaction is completed, cool down to 45°C, mix the second mixture with the photoinitiator, and stir evenly to obtain the water-washable bio-based photosensitive resin for 3D printing.

[0026] Preferably, in S1, heat up to 110°C, the vacuum dehydration time is 1 h, cool down to 60°C, add the isocyanate and the catalyst for mixing, and then heat up to 90°C again, and the stirring time is 1 h.

[0027] Preferably, the stirring time of the second mixture and the photoinitiator is 10 min.

[0028] The beneficial effects of the present invention:

[0029] The present invention uses a side-chain non-ionic hydrophilic chain extender to provide hydrophilicity to the photosensitive resin, enabling 3D printed products to have excellent water-washable performance. Due to the presence of long side chains, the side-chain non-ionic hydrophilic chain extender also imparts good flexibility to the polyurethane acrylate, increasing the elongation at break of the cured film and endowing the material with good flexibility, thus overcoming the problem of excessive brittleness of the photosensitive resin. The present invention uses hydroxyacrylate monomer as both a capping agent and a diluent in the preparation of the photosensitive resin, with a simple synthesis process and the resulting photosensitive resin having the advantage of low odor. The bio-based polyol used in the present invention is a renewable resource, and the water-washable bio-based polyurethane acrylate photosensitive resin for 3D printing prepared by replacing petroleum-based materials better meets the requirements of green environmental protection. Detailed Embodiments

[0030] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The materials, reagents, etc. used in the following embodiments can be obtained from commercial sources unless otherwise specified.

[0032] The present invention provides a water-washable bio-based photosensitive resin for 3D printing. In terms of mass fraction, the raw materials for preparation include the following components:

[0033] Bio-based polyol 11.5% - 25.5%;

[0034] Side-chain non-ionic hydrophilic chain extender 5.4% - 8.4%;

[0035] Isocyanate 4.0% - 8.3% ；

[0036] Catalyst 0.06% - 0.13% ；

[0037] Hydroxyacrylate monomer 56.7% - 76.1%;

[0038] Photoinitiator 1.0% - 2.9%;

[0039] Among them, specifically, the bio-based polyol is specifically modified castor oil polyol, and the dosages are 11.5%, 16.1%, and 25.5%; when the bio-based polyol is bio-based polytrimethylene ether glycol, the dosages are 11.5%, 16.1%, and 25.5%.

[0040] Among them, specifically, the specific values of the side-chain non-ionic hydrophilic chain extender are 5.4%, 5.5%, 5.7%, and 8.4%.

[0041] Among them, specifically, the specific values of the isocyanate are 4.0%, 6.6%, and 8.3%.

[0042] Among them, specifically, the specific values of the catalyst are 0.06%, 0.08%, 0.11%, and 0.13%.

[0043] Among them, specifically, the specific values of the hydroxyacrylate monomer are 56.7%, 69.9%, 75.9%, and 76.1%.

[0044] Among them, specifically, the specific values of the photoinitiator are 1.0%, 2.0%, and 2.9%.

[0045] Example 1

[0046] S1: Add 20 grams of modified castor oil polyol D2000 and 6.63 grams of Ymer N120 to a three-necked flask, heat up to 110 °C for vacuum dehydration for 1 h, cool down to 60 °C, add 6.5 grams of HDI to the three-necked flask, and add 0.1 gram of organic bismuth catalyst MC-710, then heat up to 90 °C and stir evenly for reaction for 1.5 h;

[0047] S2: Cool down to 60 °C, add 44.59 grams of HEMA to the three-necked flask, and then heat up to 85 °C and continue stirring for reaction for 0.5 h;

[0048] S3: After the reaction is completed, cool down to 45 °C, add 0.78 gram of photoinitiator TMO, stir evenly for 10 min, and after the product cools to room temperature, put it into a sample bottle and store it away from light.

[0049] Example 2

[0050] S1: Add 20 grams of modified castor oil polyol D2000 and 9.49 grams of Ymer N120 to a three-necked flask, heat up to 110 °C for vacuum dehydration for 1 h, cool down to 60 °C, then add 7 grams of HDI and 0.11 gram of organic bismuth catalyst MC-710, heat up to 90 °C and stir evenly for reaction for 1.5 h;

[0051] S2: Cool down to 60 °C, add 132.51 grams of HEMA to the three-necked flask, and then heat up to 85 °C and continue stirring for reaction for 0.5 h;

[0052] S3: After the reaction is completed, cool down to 45 °C, add 5.07 grams of photoinitiator TMO, stir evenly for 10 min, and after the product cools to room temperature, put it into a sample bottle and store it away from light.

[0053] Example 3

[0054] S1: Add 20 g of modified castor oil polyol D2000 and 6.75 g of Ymer N120 into a three-necked flask, heat up to 110 °C for vacuum dehydration for 1 h, cool down to 60 °C, then add 8.25 g of HDI and 0.1 g of organic bismuth catalyst MC-710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0055] S2: Cool down to 60 °C, add 87.1 g of HEMA into the three-necked flask, and then heat up to 85 °C for continuous stirring reaction for 0.5 h;

[0056] S3: After the reaction is completed, cool down to 45 °C, add 2.44 g of photoinitiator TMO, stir evenly for 10 min, and store the product in a sample bottle in the dark after it cools down to room temperature.

[0057] Example 4

[0058] S1: Add 20 g of bio-based polytrimethylene ether glycol with a molecular weight of 2000 and 6.63 g of Ymer N120 into a three-necked flask, heat up to 110 °C for vacuum dehydration for 1 h, cool down to 60 °C, then add 6.5 g of HDI and 0.1 g of organic bismuth catalyst MC-710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0059] S2: Cool down to 60 °C, add 44.59 g of HEMA into the three-necked flask, and then heat up to 85 °C for continuous uniform stirring reaction for 0.5 h;

[0060] S3: After the reaction is completed, cool down to 45 °C, add 0.78 g of photoinitiator TMO, stir evenly for 10 min, and store the product in a sample bottle in the dark after it cools down to room temperature.

[0061] Example 5

[0062] S1: Add 20 g of bio-based polytrimethylene ether glycol with a molecular weight of 2000 and 9.49 g of Ymer N120 into a three-necked flask, heat up to 110 °C for vacuum dehydration for 1 h, cool down to 60 °C, then add 7 g of HDI and 0.11 g of organic bismuth catalyst MC-710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0063] S2: Cool down to 60 °C, add 132.51 g of HEMA into the three-necked flask, and then heat up to 85 °C for continuous stirring reaction for 0.5 h;

[0064] S3: After the reaction is completed, cool down to 45 °C, add 5.07 g of photoinitiator TMO, stir evenly for 10 min, and store the product in a sample bottle in the dark after it cools down to room temperature.

[0065] Example 6

[0066] S1: Add 20 g of bio - based polytetramethylene ether glycol with a molecular weight of 2000 and 6.75 g of Ymer N120 into a three - necked flask. Heat up to 110 °C for vacuum dehydration for 1 h, then cool down to 60 °C. Then add 8.25 g of HDI and 0.1 g of organic bismuth catalyst MC - 710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0067] S2: Cool down to 60 °C, add 87.1 g of HEMA into the three - necked flask, and then heat up to 85 °C for continuous stirring reaction for 0.5 h;

[0068] S3: After the reaction is completed, cool down to 45 °C, add 2.44 g of photo - initiator TMO, stir evenly for 10 min. After the product is cooled to room temperature, put it into a sample bottle and store it in the dark.

[0069] Comparative Example 1

[0070] S1: Add 20 g of modified castor oil polyol D2000 into a three - necked flask. Heat up to 110 °C for vacuum dehydration for 1 h; cool down to 60 °C, then add 6.5 g of HDI and 0.08 g of organic bismuth catalyst MC - 710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0071] S2: Cool down to 60 °C, add 44.59 g of HEMA into the three - necked flask, and then heat up to 85 °C for continuous uniform stirring reaction for 0.5 h;

[0072] S3: After the reaction is completed, cool down to 45 °C, add 0.78 g of photo - initiator TMO, stir evenly for 10 min. After the product is cooled to room temperature, put it into a sample bottle and store it in the dark.

[0073] Comparative Example 2

[0074] S1: Add 20 g of modified castor oil polyol D2000 into a three - necked flask. Heat up to 110 °C for vacuum dehydration for 1 h; cool down to 60 °C, then add 7 g of HDI and 0.08 g of organic bismuth catalyst MC - 710, and heat up to 90 °C for uniform stirring reaction for 1.5 h;

[0075] S2: Cool down to 60 °C, add 132.51 g of HEMA into the three - necked flask, and then heat up to 85 °C for continuous stirring reaction for 0.5 h;

[0076] S3: After the reaction is completed, cool down to 45 °C, add 5.07 g of photo - initiator TMO, stir evenly for 10 min. After the product is cooled to room temperature, put it into a sample bottle and store it in the dark.

[0077] Perform performance tests on the photosensitive resins prepared in Examples 1 - 6 and Comparative Examples 1 - 2, including water - solubility tests and mechanical property tests. The test methods are as follows:

[0078] The water solubility of the photosensitive resin is judged by observing whether the resin can be dissolved in water after adding the photosensitive resin to water for dispersion. Pour the photosensitive resin onto a polytetrafluoroethylene mold and place it in an ultraviolet curing box for 60 s of light irradiation to obtain a photocured film with a wavelength of 405 nm. Take out the film and test the tensile strength and elongation at break according to the standard of GBT 1040.1-2018, and test the hardness of the film according to GB / T 2411-2018.

[0079] The raw materials of Examples 1-6 and Comparative Examples 1-2 are shown in Table 1, and the performance test results are shown in Table 2.

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085] Comparing the performance parameters in Table 2, it can be seen that in Examples 1-6, the side-chain non-ionic hydrophilic chain extender Ymer N120 was added, and the prepared products all had water solubility, while in Comparative Examples 1 and 2, the side-chain non-ionic hydrophilic chain extender was not used, and the prepared photosensitive resin was not water-soluble, indicating that the side-chain non-ionic hydrophilic chain extender Ymer N120 has a great influence on the water solubility of the resin.

[0086] Comparing Example 1 with Comparative Example 2, it can be seen that under the condition of keeping other components unchanged, the elongation at break of the photosensitive resin prepared by adding Ymer N120 increased by 51.6% compared with that prepared by omitting Ymer N120. Comparing Example 2 with Comparative Example 2, the elongation at break of Example 2 increased by 36.1%, indicating that the photocured film of the photosensitive resin prepared by using the side-chain non-ionic hydrophilic chain extender in the present invention has better flexibility.

[0087] The water-washable bio-based polyurethane acrylate photosensitive resin prepared by the present invention by using bio-based polyols and side-chain non-ionic hydrophilic chain extenders has excellent mechanical properties. The long side-chain structure of the side-chain non-ionic hydrophilic chain extender has good flexibility, which can improve the elongation at break of the material. The prepared photocured film has good flexibility, and the photosensitive resin has good water solubility and can meet the requirements of water washing, and can be applied in the field of 3D printing.

[0088] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0089] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A water-washable bio-based photosensitive resin for 3D printing, calculated by mass fraction, the raw materials include the following components: Bio-based polyol 11.5%-25.5%; Side-chain nonionic hydrophilic chain extender 5.4%-8.4%; Isocyanate 4.0%-8.3%; Catalyst 0.06%-0.13%; Hydroxyacrylate monomer 56.7%-76.1%; Photoinitiator 1.0%-2.9%.

2. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, wherein The bio-based polyol includes any one of modified castor oil polyol D2000, bio-based polytrimethylene ether glycol, cashew shell oil polyol or soybean oil polyol, with a functionality of 2 and a molecular weight of 1000-2000.

3. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, characterized in that, The side-chain nonionic hydrophilic chain extender is Ymer N120.

4. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, characterized in that, The isocyanate is any one of hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate or tetramethylbenzene diisocyanate.

5. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, characterized in that, The catalyst is an organic bismuth catalyst MC-710.

6. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, wherein The hydroxyacrylate monomer is any one of hydroxyethyl methacrylate, hydroxypropyl methacrylate or hydroxyethyl acrylate.

7. The water-washable bio-based photosensitive resin for 3D printing according to claim 1, wherein The photoinitiator is any one of 2,4,6-trimethylbenzoyl-dimethylphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoyl phenylphosphonate or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

8. A preparation method of a water-washable bio-based photosensitive resin for 3D printing, which is used to prepare the water-washable bio-based photosensitive resin for 3D printing according to any one of claims 1-7, characterized in that, It includes the following steps: S1. Heat the bio-based polyol and the side-chain nonionic hydrophilic chain extender, then dehydrate under vacuum, cool down and add the isocyanate and the catalyst for mixing, heat up again and stir to react to obtain a first mixture; S2. Cool down to 60°C, mix the first mixture with the hydroxyacrylate monomer, heat up to 85°C and continue to stir and react for 0.5 h to obtain a second mixture; S3. After the reaction is completed, cool down to 45°C, mix the second mixture with the photoinitiator, and stir evenly to obtain a water-washable bio-based photosensitive resin for 3D printing.

9. The preparation method of the water-washable bio-based photosensitive resin for 3D printing according to claim 8, characterized in that, In S1, heat up to 110°C, the vacuum dehydration time is 1 h, cool down to 60°C, add the isocyanate and the catalyst for mixing, heat up again to 90°C, and the stirring time is 1 h.

10. The preparation method of the water-washable bio-based photosensitive resin for 3D printing according to claim 8, characterized in that, The stirring time of the second mixture and the photoinitiator is 10 min.

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