Calcium phosphate continuous fiber as well as preparation method and application thereof

Abstract

The invention discloses a calcium phosphate continuous fiber and a preparation method and application thereof, and the preparation method comprises the following steps: preparing a mixed solution of a phosphorus source, ethanol and water, adding a soluble calcium salt into the mixed solution, stirring for a set time, and then adding a spinning auxiliary agent into the mixed solution to obtain a spinnable calcium phosphate precursor sol; the phosphorus source is triethyl phosphate or triethyl phosphate; carrying out dry spinning on the spinnable calcium phosphate precursor sol to obtain continuous calcium phosphate gel fibers; and drying the continuous calcium phosphate gel fiber, and carrying out heat treatment to obtain the calcium phosphate continuous fiber. The calcium phosphate continuous fiber can be prepared by adopting the preparation method disclosed by the invention, and the prepared calcium phosphate continuous fiber has the advantages of small diameter, high compactness, good flexibility and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of calcium phosphate fiber preparation, and in particular relates to a calcium phosphate continuous fiber and a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] As an important part of the human body, bones play an important role in protecting organs, providing mechanical support, and hematopoiesis. However, bone defects caused by trauma, tumor resection, or osteoporosis after population aging seriously damage human health. Bone contains about 70% calcium phosphate minerals, so calcium phosphate is the preferred material for repairing damaged bones and meets most requirements as bone biomaterials. Common calcium phosphate bone repair materials include: hydroxyapatite (HA), β-tricalcium phosphate, octacalcium phosphate, tetracalcium phosphate, etc., which have high bioactivity and biocompatibility, good bone induction ability, and the degradation products are non-toxic. They can provide rich Ca and P for bone cells to induce bone regeneration.

[0004] However, a common drawback of traditional calcium phosphate materials is that they are brittle and prone to cracking when used in load-bearing areas, limiting their application in the medical field. Fibers with a high aspect ratio can improve the strength and toughness of the matrix material by absorbing fracture energy and preventing cracks from expanding rapidly.

[0005] The fiber-shaped calcium phosphate materials prepared so far are all in the form of short fibers, whiskers or micro-nano-sized fibers, and there is no existing technology for obtaining continuous calcium phosphate fibers with small diameter, high density and good flexibility. Therefore, it is urgent to develop continuous calcium phosphate fibers to meet the requirements of the biomedical field to overcome the brittleness of calcium phosphate materials. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a calcium phosphate continuous fiber and a preparation method and application thereof. The preparation method of the present invention can be used to prepare calcium phosphate continuous fibers, and the prepared calcium phosphate continuous fibers have the advantages of small diameter, high density and good flexibility.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing continuous calcium phosphate fibers, comprising the following steps:

[0009] A mixed solution of a phosphorus source, ethanol and water is prepared, a soluble calcium salt is added thereto, the mixture is stirred for a set time, and then a spinning aid is added thereto to obtain a spinnable calcium phosphate precursor sol;

[0010] The phosphorus source is triethyl phosphite or triethyl phosphate;

[0011] The spinnable calcium phosphate precursor sol is subjected to dry spinning to obtain continuous calcium phosphate gel fibers;

[0012] The continuous calcium phosphate gel fiber is dried and then heat treated to obtain continuous calcium phosphate fiber.

[0013] Calcium phosphate belongs to ceramic materials. Due to the strong chemical bonds and a small amount of dislocation slip system in the atomic composition of ceramic materials, it is inherently hard and brittle, so how to ensure the continuity of the prepared fibers is the biggest difficulty. Common hydrothermal and solvothermal methods cannot guarantee that the final morphology is a fiber, let alone its continuity. The fiber obtained by the electrostatic spinning method is film-forming, and it is extremely difficult to separate a single fiber, which is inconsistent with the purpose of the present invention. Therefore, the present invention selects the sol-gel method and the dry spinning fiber-forming method, which can first ensure that the prepared precursor fiber is continuous. The premise for ensuring the continuity of the precursor fiber is that the precursor sol contains a certain spinnability, which requires that there are linear particles containing calcium and phosphorus sources in the precursor and that the precursor has a suitable viscosity. The linear particles are generally obtained by hydrolysis and condensation. However, calcium ions do not undergo hydrolysis, and common inorganic phosphorus sources generally exist in the form of phosphate ions. The two phosphorus sources selected by the present invention are organic phosphorus sources, and phosphorus-containing linear particles can be obtained by hydrolysis and condensation. The viscosity is adjusted and improved by the content and type of spinning aids. In addition, the spinning environment and heat treatment process are also the key to finally obtaining continuous fibers.

[0014] The mechanism of phosphorus source hydrolysis is as follows:

[0015] Triethyl phosphate:

[0016] OP(OC2H5)3+H2O→OP(C2H5O)3-x(OH)x+XC2H5OH;

[0017] 2OP(C2H5O)2(OH)→(C2H5O)2OP-O-PO(C2H5O)2+H2O;

[0018] Triethyl phosphite:

[0019] P(OC2H5)3+H2O→HP(=O)(OC2H5)2-x(OH)x+C2H5OH;

[0020] P(=O)(OC2H5)2-x(OH)x→(C2H5O)2OP-O-PO(C2H5O)2+H2O.

[0021] First, both water and ethanol are present in the reaction process of phosphorus source hydrolysis, controlling the progress of the hydrolysis reaction; second, water and ethanol are both solvents and the boiling point of ethanol is lower than that of water. During the curing stage, the ethanol can be volatilized by adjusting the temperature while the water is retained to prevent the solvent from volatilizing too quickly during the curing stage and affecting the morphology of the fiber.

[0022] In some embodiments, in the mixed solution of phosphorus source, ethanol and water, the molar ratio of phosphorus source, ethanol and water is 1:1-10:2-5.

[0023] In some embodiments, the soluble calcium salt is calcium chloride, calcium nitrate, calcium acetate or a hydrate thereof.

[0024] Preferably, the molar ratio of calcium in the soluble calcium salt to phosphorus in the phosphorus source is 2:1 to 1:1.

[0025] In some embodiments, after adding the soluble calcium salt to the mixed solution, the stirring time is 40-50 hours. The purpose of continuously stirring the mixed solution with the soluble calcium salt is to fully hydrolyze the phosphorus source and allow the calcium ions to fully enter the phosphorus-containing chain network.

[0026] In some embodiments, the spinning aid is a combination of one or more of polyvinyl alcohol, polyvinyl pyrrolidone or polyethylene oxide.

[0027] Preferably, the mass percentage of the spinning aid in the spinnable calcium phosphate precursor sol is 5%-35%.

[0028] In some embodiments, the temperature during the preparation of the spinnable calcium phosphate precursor sol is 25-35°C.

[0029] Preferably, the viscosity of the spinnable calcium phosphate precursor sol is 20-100 Pa·s.

[0030] In some embodiments, the spinning speed of the dry spinning is 50-200 rpm.

[0031] In some embodiments, the temperature for drying the continuous calcium phosphate gel fiber is 50-80°C, and the drying time is greater than 6 hours. This is to remove part of the solvent in the fiber and maintain the solidified state of the gel fiber. When the drying temperature is too high, the solvent in the precursor gel fiber evaporates and solidifies too quickly, making the surface and interior of the fiber inconsistent, forming a layer of "protective skin" on the surface, thereby hindering the further decomposition and release of internal solvents, polymers, etc. in the subsequent heat treatment stage, and then generating a large number of defects, resulting in reduced flexibility and increased brittleness.

[0032] In some embodiments, the heat treatment includes a first heat treatment and a second heat treatment, wherein the temperature of the first heat treatment is 400-550° C., and the time of the first heat treatment is 30-60 min;

[0033] The temperature of the second heat treatment is 600-1200°C, and the time of the second heat treatment is 30-60min.

[0034] The purpose of the first heat treatment is to remove residual solvents and organic polymers in the fiber.

[0035] The purpose of the second heat treatment is to obtain continuous calcium phosphate fibers mainly composed of hydroxyapatite phase.

[0036] The key step to obtain the hydroxyapatite phase is to set the appropriate calcium-phosphorus ratio, reaction temperature, reaction time and other conditions in the precursor preparation stage, so that the amorphous calcium phosphate precursor of hydroxyapatite can be obtained at this stage. The subsequent heat treatment stage provides energy for the crystal nucleus to grow further, and finally hydroxyapatite is obtained.

[0037] In a second aspect, the present invention provides a calcium phosphate continuous fiber prepared by the preparation method.

[0038] In a third aspect, the present invention provides use of the continuous calcium phosphate fibers in preparing bone repair materials.

[0039] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0040] (1) The preparation method of the calcium phosphate continuous fiber of the present invention utilizes the hydrolysis of the phosphorus source to form a chain network, and allows the calcium source to fully enter the phosphorus source hydrolysis solution to achieve uniform mixing of the phosphorus source and the calcium source at the nanoscale, which serves as the basis for preparing the calcium phosphate sol precursor. The preparation method is simple and convenient.

[0041] (2) The method for preparing continuous calcium phosphate fibers of the present invention improves the viscosity of the precursor sol and the filamentation property of the precursor by adjusting the content of the added spinning aid; at the same time, the method can form hydroxyapatite at a relatively low temperature, and low temperature is conducive to controlling the growth of hydroxyapatite.

[0042] (3) The preparation method of the calcium phosphate continuous fiber of the present invention adopts dry spinning in a sol-gel manner. The obtained calcium phosphate continuous fiber has a diameter of 1 to 10 μm, high density, good flexibility, and is mainly composed of hydroxyapatite phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0044] Figure 1 This is a SEM image of the surface of the calcium phosphate continuous fiber prepared in Example 1 of the present invention;

[0045] Figure 2 is a SEM image of a cross section of the calcium phosphate continuous fiber prepared in Example 1 of the present invention;

[0046] Figure 3 is a SEM image of the calcium phosphate continuous fiber prepared in Example 1 of the present invention;

[0047] Figure 4 is the XRD pattern of the calcium phosphate continuous fiber prepared in Example 1 of the present invention;

[0048] Figure 5 This is a physical picture of the continuous calcium phosphate gel fiber prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0050] The present invention will be further described below in conjunction with the embodiments.

[0051] Example 1

[0052] A method for preparing continuous calcium phosphate fibers comprises the following steps:

[0053] (1) triethyl phosphite, anhydrous ethanol and deionized water were mixed in a molar ratio of 1:7:3, placed in a constant temperature water bath at 30°C, and mixed under a magnetic stirring condition of 500 r / min, and stirred continuously to obtain a light yellow phosphorus source hydrolysis solution;

[0054] Then, a calcium chloride aqueous solution was added to the phosphorus source hydrolyzed solution at a molar ratio of Ca:P of 1.67, and stirring was continued until the solution became translucent;

[0055] The translucent calcium phosphate solution obtained above was mixed with a spinning aid polyvinyl pyrrolidone, wherein the mass fraction of polyvinyl pyrrolidone accounted for 10%, and the mixture was stirred continuously to obtain a spinnable calcium phosphate precursor sol with a viscosity of 33 Pa·s.

[0056] (2) The spinnable calcium phosphate precursor sol with a viscosity of 33 Pa.s obtained in step (1) is transported to a spinneret by a metering pump, and the calcium phosphate gel continuous fibers are collected and wound onto a winding shaft at a spinning speed of 130 rpm.

[0057] (3) The calcium phosphate gel continuous fiber obtained in step (2) is placed in an oven at 80°C for 24 hours for drying, and the dried calcium phosphate gel continuous fiber is placed in a heat treatment furnace for heat treatment to obtain calcium phosphate continuous fiber. The heat treatment process is set as follows: 550°C for 30 minutes, then raised to 700°C for 30 minutes.

[0058] The surface SEM image of the continuous calcium phosphate fiber prepared in Example 1 of the present invention is as follows: Figure 1 As shown in the figure, the diameter of the calcium phosphate continuous fiber is about 3.5 μm, the surface is smooth, and there is no hole defect;

[0059] The cross-sectional SEM image of the prepared continuous calcium phosphate fiber is shown in Figure 2 As shown, it can be seen that the prepared calcium phosphate continuous fibers have high density;

[0060] The SEM image of the prepared calcium phosphate continuous fiber is as follows: Figure 3 As shown, it can be seen that the diameter of the calcium phosphate continuous fibers is uniform and has good flexibility;

[0061] The X-ray diffraction results of the prepared calcium phosphate fibers are as follows: Figure 4 As shown, it can be seen that the calcium phosphate fibers are mainly composed of hydroxyapatite phase.

[0062] The actual picture of the prepared continuous calcium phosphate gel fiber is as follows Figure 5 shown.

[0063] Example 2

[0064] A method for preparing continuous calcium phosphate fibers comprises the following steps:

[0065] (1) Triethyl phosphite, anhydrous ethanol and deionized water are mixed in a molar ratio of 1:7:3, placed in a constant temperature water bath at 30°C, and mixed under a magnetic stirring condition of 500 r / min, and stirred continuously to obtain a light yellow phosphorus source hydrolysis solution; then a calcium source aqueous solution is added to the phosphorus source hydrolysis solution according to a Ca:P molar ratio of 1.67, and stirred continuously until the solution becomes translucent; then the calcium phosphate solution obtained above is mixed with a spinning aid polyvinyl pyrrolidone, wherein the mass fraction of polyvinyl pyrrolidone is 20%, and stirring is continued to obtain a spinnable calcium phosphate precursor sol with a viscosity of 60 Pa·s.

[0066] (2) The spinnable calcium phosphate precursor sol with a viscosity of 60 Pa.s obtained in step (1) is transported to a spinneret by a metering pump, and the calcium phosphate gel continuous fibers are collected and wound onto a winding shaft at a spinning speed of 180 rpm.

[0067] (3) The calcium phosphate gel continuous fiber obtained in step (2) is placed in an oven at 80°C for 24 hours for drying, and then the dried gel fiber is placed in a heat treatment furnace for heat treatment to obtain continuous calcium phosphate fiber. The heat treatment process is set to 550°C for 30 minutes, then the temperature is raised to 700°C and kept for 30 minutes.

[0068] Example 3

[0069] A method for preparing continuous calcium phosphate fibers comprises the following steps:

[0070] (1) Triethyl phosphite, anhydrous ethanol and deionized water are mixed in a molar ratio of 1:3:5, placed in a constant temperature water bath at 30°C, and mixed under a magnetic stirring condition of 600 r / min, and stirred continuously to obtain a light yellow phosphorus source hydrolysis solution; then, a calcium source aqueous solution is added to the phosphorus source hydrolysis solution according to a Ca:P molar ratio of 1.2:1, and stirred continuously for 45 hours, and the solution becomes translucent; then, the calcium phosphate solution obtained above is mixed with a spinning aid polyvinyl pyrrolidone, wherein the mass fraction of polyvinyl pyrrolidone is 20%, and stirring is continued to obtain a spinnable calcium phosphate precursor sol.

[0071] (2) The spinnable calcium phosphate precursor sol obtained in step (1) is transported to a spinneret by a metering pump, and the calcium phosphate gel continuous fibers are collected and wound onto a winding shaft at a spinning speed of 150 rpm.

[0072] (3) The calcium phosphate gel continuous fiber obtained in step (2) is placed in a 50°C oven for drying for 20 hours, and then the dried gel fiber is placed in a heat treatment furnace for heat treatment to obtain continuous calcium phosphate fiber. The heat treatment process is set to 550°C for 30 minutes, then the temperature is raised to 700°C and kept for 30 minutes.

[0073] Comparative Example 1

[0074] A method for preparing continuous calcium phosphate fibers comprises the following steps:

[0075] (1) triethyl phosphite, anhydrous ethanol and deionized water are mixed in a molar ratio of 1:7:3, placed in a constant temperature water bath at 30°C, and mixed under a magnetic stirring condition of 500 r / min, and stirred continuously to obtain a light yellow phosphorus source hydrolyzed solution; then a calcium source aqueous solution is added to the phosphorus source hydrolyzed solution according to a Ca:P molar ratio of 1.67, and stirred continuously until the solution becomes translucent; then the calcium phosphate solution obtained above is mixed with a spinning aid polyvinyl pyrrolidone, wherein the mass fraction of polyvinyl pyrrolidone accounts for 5%, and stirring is continued to obtain a spinnable calcium phosphate precursor sol with a viscosity of 8 Pa·s.

[0076] (2) The spinnable calcium phosphate precursor sol with a viscosity of 8 Pa.s obtained in step (1) is transported to a spinneret by a metering pump, and the calcium phosphate gel continuous fibers are collected and wound onto a winding shaft at a spinning speed of 60 rpm.

[0077] (3) The calcium phosphate gel continuous fiber obtained in step (2) is placed in an oven at 80°C for 24 hours for drying, and then the dried gel fiber is placed in a heat treatment furnace for heat treatment to obtain calcium phosphate fiber. The heat treatment process is set as follows: 550°C for 30 minutes, then heated to 700°C and kept for 30 minutes.

[0078] Calcium phosphate fibers were prepared in Example 3 of the present invention. During the preparation process, it was found that due to the low viscosity, the precursor sol was not easy to form into filaments, and was easily broken during the winding process. Moreover, the surface of the calcium phosphate fibers obtained after heat treatment was rough and brittle.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing continuous calcium phosphate fibers, characterized in that: The steps include: A mixed solution of a phosphorus source, ethanol and water is prepared, a soluble calcium salt is added thereto, the mixture is stirred for a set time, and then a spinning aid is added thereto to obtain a spinnable calcium phosphate precursor sol; The phosphorus source is triethyl phosphite or triethyl phosphate; The spinnable calcium phosphate precursor sol is subjected to dry spinning to obtain continuous calcium phosphate gel fibers; The continuous calcium phosphate gel fiber is dried and then heat treated to obtain continuous calcium phosphate fiber.

2. The method for preparing continuous calcium phosphate fibers according to claim 1, wherein: In the mixed solution of phosphorus source, ethanol and water, the molar ratio of phosphorus source, ethanol and water is 1:1-10:2-5.

3. The method for preparing continuous calcium phosphate fibers according to claim 1, characterized in that: The soluble calcium salt is calcium chloride, calcium nitrate, calcium acetate or a hydrate thereof; Preferably, the molar ratio of calcium in the soluble calcium salt to phosphorus in the phosphorus source is 2:1 to 1:

1.

4. The method for preparing continuous calcium phosphate fibers according to claim 3, characterized in that: After adding the soluble calcium salt to the mixed solution, the stirring time is 40-50 hours.

5. The method for preparing continuous calcium phosphate fibers according to claim 1, characterized in that: The spinning aid is a combination of one or more of polyvinyl alcohol, polyvinyl pyrrolidone or polyethylene oxide; Preferably, the mass percentage of the spinning aid in the spinnable calcium phosphate precursor sol is 5%-35%.

6. The method for preparing continuous calcium phosphate fibers according to claim 1, characterized in that: The temperature during the preparation of the spinnable calcium phosphate precursor sol is 25-35° C.; Preferably, the viscosity of the spinnable calcium phosphate precursor sol is 20-100 Pa·s.

7. The method for preparing continuous calcium phosphate fibers according to claim 1, characterized in that: The spinning speed of the dry spinning is 50-200 rpm.

8. The method for preparing continuous calcium phosphate fibers according to claim 1, characterized in that: The continuous calcium phosphate gel fiber is dried at a temperature of 50-80° C. for a drying time of more than 6 hours; Preferably, the heat treatment includes a first stage heat treatment and a second stage heat treatment, wherein the temperature of the first stage heat treatment is 400-550°C and the time of the first stage heat treatment is 30-60min; The temperature of the second heat treatment is 600-1200°C, and the time of the second heat treatment is 30-60min.

9. A calcium phosphate continuous fiber, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the continuous calcium phosphate fiber according to claim 9 in the preparation of bone repair materials.

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