Short-cut fiber reinforced photosensitive resin for 3D printing and method of making the same

Abstract

This application provides a photosensitive resin for 3D printing reinforced with chopped fibers. The amount of reinforcing material is 17%-25% of the mass of the photosensitive resin matrix, and the amount of fiber dispersant is 0.3%-0.8% of the mass of the reinforcing material. The preparation of the reinforcing material includes the following steps: dissolving a dialkoxysilane coupling agent in an acidic solution to undergo a double condensation reaction to obtain a pretreatment solution. The pH of the acidic solution is 3-6, and the concentration of the dialkoxysilane coupling agent in the pretreatment solution is 2wt%-4.5wt%. The reaction time for obtaining the pretreatment solution is 30-40 minutes. Chopped fibers with active groups are mixed into the pretreatment solution to obtain a mixture. The active groups include hydroxyl groups, and the mass ratio of chopped fibers to dialkoxysilane coupling agent is 18-30:1. The mixture is heat-treated under an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours. This application also provides a method for preparing the photosensitive resin. The tensile strength of the object obtained by curing the photosensitive resin provided in this application using 3D printing technology is higher than 70 MPa.

Description

Technical Field

[0001] This invention relates to the technical field of photosensitive resins, and more specifically to a photosensitive resin for 3D printing chopped fiber reinforcement and its preparation method. Background Technology

[0002] The photosensitive resin used in 3D printing technology has the problem of low tensile strength. Currently, the strength of the photosensitive resin can be improved by adding fibers. In order to solve the problem of fiber dispersion, silane coupling agents are usually used to wet the fibers into the photosensitive resin matrix. However, this method has the problem of limited reinforcement and it is difficult to further improve the tensile strength of the photosensitive resin. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a photosensitive resin for 3D printing of chopped fiber reinforcement, so that the tensile strength of the object after the photosensitive resin is printed and cured by 3D printing technology can be higher than 70MPa.

[0004] This application also provides a method for preparing photosensitive resins.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A photosensitive resin for 3D printing chopped fiber reinforcement, the photosensitive resin comprising a photosensitive resin matrix, a reinforcing agent, and a fiber dispersant, wherein the amount of the reinforcing agent is 17%-25% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.3%-0.8% of the mass of the reinforcing agent. The preparation of the reinforcing agent includes the following steps:

[0007] A pretreatment solution is obtained by dissolving a dialkoxysilane coupling agent in an acidic solution to undergo a double condensation reaction. The pH value of the acidic solution is 3-6. The concentration of the dialkoxysilane coupling agent in the pretreatment solution is 2wt%-4.5wt%. The reaction time to obtain the pretreatment solution is 30-40 minutes.

[0008] Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture, wherein the active groups include hydroxyl groups, and the mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:1.

[0009] The mixture is heat-treated in an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours, and then cooled and discharged to obtain the reinforcing material.

[0010] In some possible implementations, the amount of the reinforcing material is 20%-23% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.5%-0.8% of the mass of the reinforcing material.

[0011] In some possible implementations, the mass ratio of the chopped fibers to the dialkoxysilane coupling agent is 20-25:1.

[0012] In some possible implementations, the heat treatment temperature of the mixture is 550-700°C, and the heat treatment time is 1-1.2 hours.

[0013] In some possible implementations, the fiber dispersant is selected from sodium dodecylbenzenesulfonate and polyethylene glycol.

[0014] In some possible embodiments, the dialkoxysilane coupling agent is selected from at least one of N-aminoethyl-3-aminopropylmethyldimethoxysilane and γ-methacryloyloxymethyldimethoxysilane.

[0015] In some possible embodiments, the photosensitive resin matrix comprises, by weight, the following components in proportion: 20-60 parts of oligomer, 10-25 parts of monomer diluent, and 1-5 parts of photoinitiator.

[0016] In some possible implementations, the oligomer is selected from polyurethane acrylate, and the monomer diluent is selected from trimethylolpropane triacrylate.

[0017] This application also provides a method for preparing a photosensitive resin, the method comprising the following steps:

[0018] To prepare the reinforcing material, specifically, a dialkoxysilane coupling agent is dissolved in an acidic solution to undergo a double condensation reaction to obtain a pretreatment solution. The pH value of the acidic solution is 3-6. In the pretreatment solution, the concentration of the dialkoxysilane coupling agent is 2wt%-4.5wt%. The reaction time for obtaining the pretreatment solution is 30-40 minutes. Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture. The active groups include hydroxyl groups. The mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:1. The mixture is heat-treated under an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours. After cooling, the reinforcing material is obtained.

[0019] The fiber dispersant is uniformly mixed into the photosensitive resin matrix, and then the reinforcing material is stirred in.

[0020] In some possible implementations, when the reinforcing material is mixed in, the stirring speed is 1000-2000 r / min and the stirring time is 20-30 minutes.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] In this application, by introducing a method for preparing a reinforcing material, inorganic particles formed by in-situ pyrolysis of a silane coupling agent after heat treatment are incorporated into the surface of chopped fibers. This allows the reinforcing material to further increase the tensile strength of objects printed by 3D printing technology using photosensitive resin, resulting in a tensile strength exceeding 70 MPa after curing. Furthermore, the preparation method provided in this application facilitates uniform material mixing.

[0023] The present invention will be further described in detail below with reference to specific embodiments. Detailed Implementation

[0024] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] One embodiment of this application provides a photosensitive resin for 3D printing chopped fiber reinforcement, hereinafter referred to as photosensitive resin. The photosensitive resin includes a photosensitive resin matrix, a reinforcing material, and a fiber dispersant. The amount of the reinforcing material is 17%-25% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.3%-0.8% of the mass of the reinforcing material. The fiber dispersant is used to improve the dispersibility of the reinforcing material in the photosensitive resin matrix. The preparation of the reinforcing material includes the following steps.

[0028] A pretreatment solution is obtained by dissolving a dialkoxysilane coupling agent in an acidic solution and undergoing a dicondensation reaction. The pH of the acidic solution is 3-6. For example, the acidic solution can be selected from dilute HCl or dilute nitric acid. For example, the dialkoxysilane coupling agent can be of the structure YR-SiH(OR)2 or YR-SiR(OR)2, where Y represents an organic functional group and R represents an alkyl group. In an acidic environment, the dialkoxysilane coupling agent hydrolyzes to generate silanediol, and each silanediol retains a hydroxyl group after dicondensation. In the pretreatment solution, the concentration of the dialkoxysilane coupling agent is 2wt%-4.5wt%, and the reaction time to obtain the pretreatment solution is 30-40 minutes.

[0029] Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture, wherein the active groups include hydroxyl groups, and the mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:1. Exemplarily, the short-cut fibers can be at least one of short-cut carbon fibers and short-cut aramid fibers. Exemplarily, the length of the short-cut fibers can be 1-15 mm. Exemplarily, active groups can be introduced onto the surface of the short-cut fibers by plasma treatment, chemical oxidation, and electrochemical oxidation. Exemplarily, short-cut fibers with active groups can be prepared by heating and oxidizing the short-cut fibers in hydrogen peroxide, filtering, and then reducing them in a hydrogen atmosphere. Exemplarily, the oxidation temperature is 50-70°C, and the treatment time is 1-2 hours. The reduction temperature is 50-60°C, and the reduction time is 10-30 minutes. Exemplarily, short-cut fibers with active groups can also be obtained by treatment with concentrated nitric acid. It is understood that active groups can be introduced by any existing feasible method, or short-cut fibers with active groups can be obtained by purchase. Short-cut fibers with active groups can be bonded to a silane coupling agent after dicondensation.

[0030] The mixture is heat-treated in an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours, and then cooled to obtain the reinforcing material. After high-temperature treatment, the condensed silane coupling agent is pyrolyzed in situ to generate inorganic particles. For example, it can be cooled to room temperature before discharge.

[0031] In this application, by introducing a method for preparing a reinforcing material, inorganic particles formed by in-situ pyrolysis of a silane coupling agent after heat treatment are incorporated into the surface of chopped fibers. This allows the reinforcing material to further increase the tensile strength of objects printed by 3D printing technology using photosensitive resin, resulting in a tensile strength exceeding 70 MPa after curing. Furthermore, the preparation method provided in this application facilitates uniform material mixing.

[0032] In some embodiments, the amount of the reinforcing material is 20%-23% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.5%-0.8% of the mass of the reinforcing material. Further preferred amounts are beneficial for further improving tensile strength.

[0033] In some embodiments, the mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 20-25:1. Further limiting the mass ratio also helps to further improve the tensile strength.

[0034] In some embodiments, the heat treatment temperature of the mixture is 550-700°C, and the heat treatment time is 1-1.2 hours.

[0035] In some embodiments, the fiber dispersant is selected from sodium dodecylbenzenesulfonate and polyethylene glycol.

[0036] In some embodiments, the dialkoxysilane coupling agent is selected from at least one of N-aminoethyl-3-aminopropylmethyldimethoxysilane and γ-methacryloyloxymethyldimethoxysilane. The selection of the coupling agent is based on optimization of steric hindrance and bonding strength, thereby ensuring that the pyrolyzed inorganic particles can be stably fixed on the chopped fibers.

[0037] In some embodiments, the photosensitive resin matrix comprises, by weight, the following components in the following proportions: 20-60 parts of oligomer, 20-25 parts of monomer diluent, and 1-5 parts of photoinitiator.

[0038] In some embodiments, the oligomer is selected from polyurethane acrylate, and the monomer diluent is selected from trimethylolpropane triacrylate.

[0039] For example, the photoinitiator can be a conventional photocurable initiator, such as either photoinitiator TPO or photoinitiator 819.

[0040] Another embodiment of this application provides a method for preparing a photosensitive resin, the method being used to prepare a photosensitive resin as described in any one of the above product embodiments, the method comprising the following steps.

[0041] To prepare the reinforcing material, specifically, a dialkoxysilane coupling agent is dissolved in an acidic solution to undergo a double condensation reaction to obtain a pretreatment solution. The pH value of the acidic solution is 3-6. In the pretreatment solution, the concentration of the dialkoxysilane coupling agent is 2wt%-4.5wt%. The reaction time for obtaining the pretreatment solution is 30-40 minutes. Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture. The active groups include hydroxyl groups. The mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:1. The mixture is heat-treated under an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours. After cooling, the reinforcing material is obtained.

[0042] The fiber dispersant is uniformly mixed into the photosensitive resin matrix, and then the reinforcing material is mixed in by stirring. For example, the fiber dispersant can be mixed into the photosensitive resin matrix by stirring, with an exemplary stirring speed of 100-300 rpm. In some embodiments, when mixing in the reinforcing material, the stirring speed is 1000-2000 rpm, and the stirring time is 20-30 minutes. A preferred stirring speed for the reinforcing material facilitates effective and rapid mixing while avoiding material splashing. For example, the mixing time for the fiber dispersant can be 10-30 minutes.

[0043] The following is a detailed description of the embodiments.

[0044] Example 1

[0045] A photosensitive resin for 3D printing chopped fiber reinforcement, the photosensitive resin comprising a photosensitive resin matrix, a reinforcing agent, and a fiber dispersant (sodium dodecylbenzenesulfonate, Qianyao Technology). The photosensitive resin matrix, by weight, comprises the following components in the following proportions: 20 parts of oligomer (polyurethane acrylate 271, brand SC, Shandong Shoucheng Chemical Co., Ltd.), 15 parts of monomer diluent (trimethylolpropane triacrylate, 2136, brand TMPTA), and 1 part of photoinitiator (TPO).

[0046] The amount of the reinforcing material is 17% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.4% of the mass of the reinforcing material. The preparation of the reinforcing material includes the following steps:

[0047] A pretreatment solution was obtained by dissolving a dialkoxysilane coupling agent (N-aminoethyl-3-aminopropylmethyldimethoxysilane) in an acidic solution (dilute hydrochloric acid aqueous solution, pH 6) to undergo a double condensation reaction. The concentration of the dialkoxysilane coupling agent in the pretreatment solution was 2 wt%, and the reaction time to obtain the pretreatment solution was 40 minutes.

[0048] Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture, wherein the active groups include hydroxyl groups, and the mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 19:1.

[0049] The mixture is heat-treated in an inert atmosphere (nitrogen atmosphere) at a temperature of 650°C for 1.3 hours, and then cooled and discharged (at room temperature) to obtain the reinforcing material.

[0050] For example, chopped fibers with active groups can be prepared by the following steps: Commercially available chopped carbon fibers (1 mm in length, Carbonene Technology Co., Ltd.) are first immersed in hydrogen peroxide (for example, 1 kg of chopped carbon fibers can be immersed in 1 L of 30 wt% hydrogen peroxide), heated to 50°C and stirred for 1 hour, filtered to obtain oxidized chopped carbon fibers, and then transferred to a heat pipe for reduction under a hydrogen atmosphere for 10 minutes to obtain chopped carbon fibers with hydroxyl active groups.

[0051] In this embodiment, the preparation of the photosensitive resin includes the steps of preparing a reinforcing material (already described above and will not be repeated for simplicity), uniformly mixing a fiber dispersant into the photosensitive resin matrix, and stirring to mix the reinforcing material into the photosensitive resin matrix containing the fiber dispersant. During the fiber dispersant mixing step, the stirring speed is 150 r / min. During the reinforcing material mixing step, the stirring speed is 1000 r / min, and the stirring time is 20 minutes.

[0052] The aforementioned photosensitive resin can be photocured using ultraviolet light in the range of 365-405 nm (395 nm is selected) to obtain molded parts (using photocuring molding technology based on 3D printing technology). The intensity of the ultraviolet light can be set to 100-110 W / cm². 2 (Example, 100W / cm) 2 The UV curing time can be controlled within 10 minutes (for example, 3 minutes).

[0053] Example 2

[0054] The difference from Example 1 is that the fiber dispersant used is polyethylene glycol (PEG-1000, Huisong New Materials), the oligomer content is 40 parts by mass, the monomer diluent content is 20 parts by mass, and the photoinitiator (photoinitiator 819, Sigma) content is 4 parts. The amount of the reinforcing material is 19% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.6% of the mass of the reinforcing material. The 3D printing curing wavelength is 365nm.

[0055] Example 3

[0056] The difference from Example 1 is that the diekoxysilane coupling agent is γ-methacryloyloxymethyldimethoxysilane.

[0057] Example 4

[0058] The difference from Example 1 is that, in the preparation of the reinforcing material, the pH value of the acidic solution is 3, the concentration of the dialkoxysilane coupling agent is 4.5 wt%, and the reaction time to obtain the pretreatment solution is 35 minutes. When the reinforcing material is mixed in, the stirring speed is 1300 r / min, and the stirring time is 22 minutes.

[0059] Example 5

[0060] The difference from Example 1 is that the oligomer comprises 60 parts by mass, the monomer diluent comprises 10 parts by mass, and the photoinitiator comprises 5 parts by mass. The amount of the reinforcing material is 20% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.5% of the mass of the reinforcing material. The mass ratio of the chopped fibers to the dialkoxysilane coupling agent is 20:1. The heat treatment temperature of the mixture is 700°C, and the heat treatment time is 1 hour. When the reinforcing material is mixed in, the stirring speed is 1500 r / min, and the stirring time is 30 minutes.

[0061] Example 6

[0062] The difference from Example 1 is that the oligomer has a mass fraction of 50 parts, the monomer diluent has a mass fraction of 25 parts, and the photoinitiator has a mass fraction of 5 parts. The amount of the reinforcing material is 23% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.8% of the mass of the reinforcing material. The mass ratio of the chopped fibers to the dialkoxysilane coupling agent is 25:1. The heat treatment temperature of the mixture is 550°C, and the heat treatment time is 1.2 hours. When the reinforcing material is mixed in, the stirring speed is 1300 r / min, and the stirring time is 25 minutes.

[0063] Example 7

[0064] The difference from Example 6 is that the amount of the reinforcing material is 25% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.4% of the mass of the reinforcing material.

[0065] Example 8

[0066] The difference from Example 6 is that the amount of the reinforcing material is 24% of the mass of the photosensitive resin matrix, the amount of the fiber dispersant is 0.3% of the mass of the reinforcing material, the mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 18:1, the heat treatment temperature of the mixture is 500°C, and the heat treatment time is 1.5 hours.

[0067] Example 9

[0068] The difference from Example 6 is that the mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 27:1, the heat treatment temperature of the mixture is 800°C, and the heat treatment time is 1.3 hours.

[0069] Example 10

[0070] The difference from Example 1 is that the length of the chopped fiber is 6 mm.

[0071] Example 11

[0072] The difference from Example 1 is that the length of the chopped fiber is 10 mm.

[0073] Example 12

[0074] The difference from Example 1 is that the length of the chopped fiber is 12 mm.

[0075] Example 13

[0076] The difference from Example 1 is that the length of the chopped fibers is 15 mm. The chopped fibers were purchased from the same manufacturer and will not be described further.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that, in the preparation of the reinforcing material, the short-cut fibers with active groups are directly dispersed in the diekoxysilane coupling agent, omitting the coupling agent condensation treatment step and the heat treatment step, and then mixed into the photosensitive resin matrix for use.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that the amount of the reinforcing material is 16% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.2% of the mass of the reinforcing material.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the amount of the reinforcing material is 26% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.8% of the mass of the reinforcing material.

[0083] Comparative Example 4

[0084] The difference from Example 1 is that the mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 17:1.

[0085] Comparative Example 5

[0086] The difference from Example 1 is that the mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 31:1.

[0087] This application tests tensile strength properties according to the national standard GB / T 1040.1-2018. The test results of the above embodiments and comparative examples are shown in the table below.

[0088]

[0089] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A 3D printing short-cut fiber-reinforced photosensitive resin, characterized in that, The photosensitive resin comprises a photosensitive resin matrix, a reinforcing material, and a fiber dispersant. The amount of the reinforcing material is 17%-25% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.3%-0.8% of the mass of the reinforcing material. The preparation of the reinforcing material includes the following steps: A pretreatment solution is obtained by dissolving a dialkoxysilane coupling agent in an acidic solution to undergo a double condensation reaction. The pH value of the acidic solution is 3-6. The concentration of the dialkoxysilane coupling agent in the pretreatment solution is 2wt%-4.5wt%. The reaction time to obtain the pretreatment solution is 30-40 minutes. Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture, wherein the active groups include hydroxyl groups, and the mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:

1. The mixture is heat-treated in an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours, and then cooled and discharged to obtain the reinforcing material.

2. The photosensitive resin according to claim 1, wherein The amount of the reinforcing material is 20%-23% of the mass of the photosensitive resin matrix, and the amount of the fiber dispersant is 0.5%-0.8% of the mass of the reinforcing material.

3. The photosensitive resin according to claim 1, wherein The mass ratio of the chopped fiber to the dialkoxysilane coupling agent is 20-25:

1.

4. The photosensitive resin according to claim 1, wherein The heat treatment temperature of the mixture is 550-700℃, and the heat treatment time is 1-1.2 hours.

5. The photosensitive resin as described in claim 1, characterized in that, The fiber dispersant is selected from sodium dodecylbenzenesulfonate and polyethylene glycol.

6. The photosensitive resin according to claim 1, wherein The diekoxysilane coupling agent is selected from at least one of N-aminoethyl-3-aminopropylmethyldimethoxysilane and γ-methacryloyloxymethyldimethoxysilane.

7. The photosensitive resin according to claim 1, wherein The photosensitive resin matrix comprises, by weight, the following components in the following proportions: 20-60 parts of oligomer, 10-25 parts of monomer diluent, and 1-5 parts of photoinitiator.

8. The photosensitive resin as described in claim 7, characterized in that, The oligomer is selected from polyurethane acrylate, and the monomer diluent is selected from trimethylolpropane triacrylate.

9. A method for producing a photosensitive resin, characterized by, The preparation method is used to prepare the photosensitive resin according to any one of claims 1 to 8, and the preparation method includes the following steps: To prepare the reinforcing material, specifically, a dialkoxysilane coupling agent is dissolved in an acidic solution to undergo a double condensation reaction to obtain a pretreatment solution. The pH value of the acidic solution is 3-6. In the pretreatment solution, the concentration of the dialkoxysilane coupling agent is 2wt%-4.5wt%. The reaction time for obtaining the pretreatment solution is 30-40 minutes. Short-cut fibers with active groups are mixed into the pretreatment solution to obtain a mixture. The active groups include hydroxyl groups. The mass ratio of the short-cut fibers to the dialkoxysilane coupling agent is 18-30:

1. The mixture is heat-treated under an inert atmosphere at a temperature of 500-800°C for 1-1.5 hours. After cooling, the reinforcing material is obtained. The fiber dispersant is uniformly mixed into the photosensitive resin matrix, and then the reinforcing material is stirred in.

10. The preparation method according to claim 9, characterized in that, When the reinforcing material is mixed in, the stirring speed is 1000-2000 r / min and the stirring time is 20-30 minutes.

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