Polyhydroxyalkanoate composite material, oral care product and preparation method of oral care product

Abstract

The invention discloses a polyhydroxyalkanoate composite material, an oral care product and a preparation method of the oral care product, and belongs to the technical field of bio-based high polymer materials. Wherein the polyhydroxyalkanoate composite material is prepared from the following components in percentage by mass: 82 percent to 98.5 percent of polyhydroxyalkanoate, 1 percent to 15 percent of hydroxyapatite and 0.5 percent to 3 percent of triethyl citrate. The composite material disclosed by the invention can be used for improving the mechanical property while inhibiting the water absorption, so that the dimensional stability and the long-term use stability of the oral care product are favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bio-based polymer materials, and in particular to a polyhydroxyalkanoate composite material, an oral care product and a preparation method thereof. Background Art

[0002] The handles of oral care products like dental floss and toothbrushes are often made of petroleum-based plastics such as polypropylene (PP), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS). While these materials are inexpensive and easy to process, their waste can cause persistent environmental pollution. Therefore, finding alternative materials with superior performance, biodegradability, and safety has become a key development direction for the oral care product industry.

[0003] Polyhydroxyalkanoates (PHAs) are considered candidate materials for oral care products due to their biosynthetic origin, biodegradability under certain conditions, and potential good biocompatibility. However, PHA materials are somewhat hydrophilic. In the oral environment, where they are frequently exposed to water and saliva, they may absorb water and swell, leading to a decrease in mechanical properties and even accelerated material degradation, thus shortening the product's lifespan. Summary of the Invention

[0004] The main purpose of the present invention is to provide a polyhydroxyalkanoate composite material, an oral care product and a preparation method thereof, aiming to inhibit the water absorption of PHA while improving the mechanical properties of the PHA material.

[0005] In a first aspect, the present invention provides a polyhydroxyalkanoate composite material comprising the following components in percentage by mass: 82%-98.5% polyhydroxyalkanoate, 1%-15% hydroxyapatite, and 0.5%-3% triethyl citrate.

[0006] In some embodiments, the polyhydroxyalkanoate includes at least one of a P3HB3HP copolymer and a P3HB4HB copolymer.

[0007] In some embodiments, the content of 3-hydroxypropionate units in the P3HB3HP copolymer is 3 mol%-8 mol%; and / or the content of 4-hydroxybutyrate units in the P3HB4HB copolymer is 3 mol%-8 mol%.

[0008] In some embodiments, the weight average molecular weight of the P3HB3HP copolymer and the P3HB4HB copolymer are both 500 kDa-1000 kDa.

[0009] In some embodiments, the average particle size of the hydroxyapatite is 20 nm-200 nm.

[0010] In some embodiments, the mass percentage of the hydroxyapatite is 5%-12%; and / or the mass percentage of the triethyl citrate is 1%-2.5%.

[0011] In a second aspect, the present invention provides an oral care product comprising any one of the polyhydroxyalkanoate composite materials described above.

[0012] In some embodiments, the oral care product includes at least one of a floss pick handle and a toothbrush handle.

[0013] The third invention provides a method for preparing an oral care product, comprising:

[0014] Provide polyhydroxyalkanoate and hydroxyapatite, wherein the water content of the polyhydroxyalkanoate and the hydroxyapatite is less than 0.05wt%; provide triethyl citrate; blend the polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate, and then granulate to obtain composite material particles, wherein the mass percentage of the polyhydroxyalkanoate is 82%-98.5%, the mass percentage of the hydroxyapatite is 1%-15%, and the mass percentage of the triethyl citrate is 0.5%-3%; and process the composite material particles into shapes to obtain an oral care product.

[0015] In some embodiments, the step of granulating after blending the polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate includes: preparing a masterbatch of the hydroxyapatite and part of the polyhydroxyalkanoate or part of the triethyl citrate, and then blending with the remaining components; or, first mixing and melting the polyhydroxyalkanoate and the triethyl citrate, and then adding the hydroxyapatite for blending; or, blending the polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate at a rotation speed of 100 rpm-250 rpm.

[0016] The polyhydroxyalkanoate composite material of the present invention includes hydroxyapatite, which can improve the rigidity of the composite material as an inorganic filler and can meet the mechanical performance requirements required for oral care products. In addition, the hydrophobic properties of hydroxyapatite (compared to polyhydroxyalkanoate) can form a water-blocking network, thereby helping to reduce the water absorption rate of the composite material. Therefore, the composite material of the present invention can improve mechanical properties while suppressing water absorption, thereby helping to improve the dimensional stability and long-term use stability of oral care products.

[0017] In addition, the present invention uses hydroxyapatite as the primary reinforcement while introducing a low content of triethyl citrate as an auxiliary agent. Triethyl citrate can not only improve the melt fluidity of the material, facilitating processing and molding, but also compensate to a certain extent for the toughness loss that may be caused by the addition of rigid fillers, ensuring that the oral care product is not prone to brittle fracture when subjected to accidental impact or bending, thereby achieving a good balance between rigidity, toughness and processability. DETAILED DESCRIPTION

[0018] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. "At least one" appearing in the embodiments of the present invention refers to one or more, and "more" refers to two or more.

[0019] The "ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range.

[0020] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0021] The handles of oral care products such as dental flossers and toothbrushes generally require high stiffness and strength to ensure effective force transmission and shape retention during use. However, due to the hydrophilicity of PHA materials, they may absorb water and swell in the oral environment, where they are frequently exposed to water and saliva. This can lead to a decrease in mechanical properties and even accelerated material degradation, shortening the product's service life.

[0022] Although in some embodiments, two or more hydroxy fatty acid monomers are copolymerized to obtain polyhydroxy fatty acid esters to improve their brittleness and flexibility, conventional copolymers still cannot meet the requirements of suppressing water absorption while having high stiffness and strength.

[0023] In order to solve the above problems, the present invention provides a polyhydroxyalkanoate composite material, comprising the following components in percentage by mass: 82%-98.5% polyhydroxyalkanoate, 1%-15% hydroxyapatite, and 0.5%-3% triethyl citrate.

[0024] Polyhydroxyalkanoate (PHA) as a matrix provides biodegradability, biocompatibility and renewability, and its content can be any value between 82% and 98.5%. Exemplarily, the mass percentage of polyhydroxyalkanoate can be 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96% or 98.5%.

[0025] Hydroxyapatite (HAp) is a natural calcium phosphate mineral with a chemical composition of Ca 10 (PO4)6(OH)2. Compared with PHA, hydroxyapatite has hydrophobic properties. As a water absorption inhibitory filler, it can form a water-blocking network in the matrix, thereby helping to reduce the equilibrium water absorption rate of the composite material. In addition, as an inorganic mineral, hydroxyapatite has high hardness and rigidity. When it is dispersed into the polyhydroxyalkanoate matrix as a filler, it can hinder the relative slippage of the polyhydroxyalkanoate molecular chain and limit its deformation when subjected to force, thereby helping to improve the rigidity of the composite material. In addition, hydroxyapatite is biocompatible and degradable, which can further enhance the biocompatibility of the composite material.

[0026] In some embodiments, in order to improve the interfacial compatibility between hydroxyapatite and the polyhydroxyalkanoate matrix, the hydroxyapatite may be surface treated with a silane coupling agent (such as KH550 or KH570).

[0027] The amount of hydroxyapatite added may be any value between 1% and 15%. For example, the amount of hydroxyapatite added may be 1%, 3%, 5%, 8%, 10%, 12% or 15%.

[0028] Triethyl citrate (TEC) as an additive can, on the one hand, compensate for the potential loss of toughness associated with the addition of hydroxyapatite rigid filler, reducing the risk of brittle fracture in the product when subjected to unexpected impact or bending, thereby achieving a good balance between rigidity and toughness. Furthermore, TEC improves the material's melt flowability, facilitating processing. Furthermore, TEC is a biodegradable, bio-based chemical, making the entire composite material system compliant with green and sustainable development concepts and helping to reduce the environmental impact of traditional plastic waste.

[0029] The addition amount of triethyl citrate can be any value between 0.5% and 3%. For example, the addition amount of triethyl citrate can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.7% or 3%.

[0030] When the addition amount of hydroxyapatite is between 1% and 15% and the addition amount of triethyl citrate is between 0.5% and 3%, the rigidity and toughness of the composite material can be balanced, and the equilibrium water absorption rate of the composite material can be effectively suppressed.

[0031] According to some embodiments of the present invention, the polyhydroxyalkanoate includes at least one of a P3HB3HP copolymer and a P3HB4HB copolymer.

[0032] P3HB3HP copolymer refers to a polymer obtained by copolymerization of 3-hydroxybutyrate (3HB) and 3-hydroxypropionate (3HP), and P3HB4HB refers to a polymer obtained by copolymerization of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB).

[0033] The crystallinity of traditional P3HB (homopolymer of 3HB) is between 60% and 80%, and it has certain rigidity and crystallinity. By introducing an appropriate amount of 3HP or 4HB monomer, the high crystallinity of P3HB can be reduced, making the composite material extremely rigid and having improved flexibility.

[0034] According to some embodiments of the present invention, the content of 3-hydroxypropionate units in the P3HB3HP copolymer is 3 mol%-8 mol%; and / or the content of 4-hydroxybutyrate units in the P3HB4HB copolymer is 3 mol%-8 mol%.

[0035] In the P3HB3HP copolymer, the 3-hydroxypropionate unit content is 3 mol% to 8 mol%, which means that in the molecular chain of P3HB3HP, the amount of 3HP monomer units accounts for 3% to 8% of the total monomer units (3HB + 3HP). The same applies to the 4-hydroxybutyrate unit content in the P3HB4HB copolymer, which is 3 mol% to 8 mol%.

[0036] When the content of 3-hydroxypropionate units is 3 mol%-8 mol% or the content of 4-hydroxybutyrate units is 3 mol%-8 mol%, the crystallinity of pure P3HB can be reduced from 60%-63% to 45%-55%, which can both ensure the rigidity of the composite material and improve the toughness of the composite material.

[0037] According to some embodiments of the present invention, the weight average molecular weight of the P3HB3HP copolymer and the P3HB4HB copolymer are both 500 kDa-1000 kDa.

[0038] The weight-average molecular weight (Mw) of the P3HB3HP copolymer or the P3HB4HB copolymer is 500 kDa-1000 kDa. The high molecular weight ensures that the material itself has sufficient cohesive strength, avoiding insufficient strength of the composite material due to too low a molecular weight. In addition, the appropriate molecular weight range ensures moderate viscosity of the melt during processing, facilitating melt blending with other components.

[0039] According to some embodiments of the present invention, the average particle size of hydroxyapatite is 20 nm-200 nm.

[0040] The average particle size of the hydroxyapatite can be any value between 20 nm and 200 nm. For example, the average particle size of the hydroxyapatite can be 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, or 200 nm. Nanoscale hydroxyapatite can further enhance the strength of the polyhydroxyalkanoate composite and improve toughness. In some embodiments, the average particle size of the hydroxyapatite is a volume average particle size, which can be represented by Dv50.

[0041] In some embodiments, the hydroxyapatite may be rod-shaped, in which case the average length thereof is between 20 nm and 200 nm, and the average diameter thereof is also between 20 nm and 200 nm.

[0042] According to some embodiments of the present invention, the mass percentage of hydroxyapatite is 5%-12%; and / or the mass percentage of triethyl citrate is 1%-2.5%.

[0043] According to some embodiments of the present invention, the present invention further provides an oral care product comprising any one of the polyhydroxyalkanoate composite materials described above.

[0044] According to some embodiments of the present invention, the oral care product includes at least one of a dental floss handle and a toothbrush handle.

[0045] According to some embodiments of the present invention, the present invention also provides a method for preparing an oral care product, comprising: providing polyhydroxyalkanoate and hydroxyapatite, wherein the water content of the polyhydroxyalkanoate and the hydroxyapatite is less than 0.05 wt%; providing triethyl citrate; blending the polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate and granulating them to obtain composite material particles, wherein the mass percentage of the polyhydroxyalkanoate is 82%-98.5%, the mass percentage of the hydroxyapatite is 1%-15%, and the mass percentage of the triethyl citrate is 0.5%-3%; and processing the composite material particles into a shape to obtain an oral care product.

[0046] A water content of polyhydroxyalkanoates below 0.05 wt% can avoid molecular weight loss that may be caused by excessively high water content. A water content of hydroxyapatite below 0.05 wt% can reduce water-mediated dissolution or chemical changes, ensuring its functional stability. In some embodiments, to obtain polyhydroxyalkanoates and hydroxyapatite with a water content below 0.05 wt%, the polyhydroxyalkanoates and hydroxyapatite can be vacuum dried at 80°C-100°C for 4-6 hours, respectively. Drying in a vacuum environment can effectively control the moisture content of the raw materials and avoid high-temperature hydrolysis of the polyhydroxyalkanoates. Limiting the drying time can also reduce thermal oxidative degradation of the polyhydroxyalkanoates.

[0047] Polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate can be blended using a twin-screw extruder, where the three materials undergo longitudinal and transverse shear between the screws, resulting in more uniform mixing. In some embodiments, the blending temperature can be set between 160°C and 185°C to achieve melt blending. After mixing, the materials are extruded from the extruder head to obtain a molten strip material. After cooling in a water tank or air cooling, a pelletizer is used to form uniform composite material particles.

[0048] The composite particles can be processed into oral care products using processes such as injection molding, compression molding, and extrusion molding. In some embodiments, the composite particles can be vacuum-dried at 70°C-90°C for 2-4 hours before molding. This reduces moisture absorption by the composite particles during storage, avoids bubbles and surface defects during injection molding, and ensures a smooth surface finish.

[0049] According to some embodiments of the present invention, the step of granulating after blending polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate includes: preparing a masterbatch of hydroxyapatite and part of the polyhydroxyalkanoate or part of the triethyl citrate, and then blending with the remaining components; or, first mixing and melting the polyhydroxyalkanoate and triethyl citrate, and then adding hydroxyapatite for blending; or, blending the polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate at a rotation speed of 100 rpm-250 rpm.

[0050] The above method can achieve good dispersion of hydroxyapatite, helping to form uniform composite particles. Adding hydroxyapatite to the molten polyhydroxyapatite / triethyl citrate mixture can reduce hydroxyapatite agglomeration at high temperatures. Furthermore, when using a screw extruder for melt blending, a special screw element combination with strong dispersive mixing capabilities (such as a kneading block or toothed disk) can be selected to further uniformly disperse the hydroxyapatite.

[0051] Example 1

[0052] [Polyhydroxyalkanoate composite materials]

[0053] Components: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 88.5%, hydroxyapatite 10%, triethyl citrate 1.5%. The product brand of P3HB3HP is Heng Carbon Z2501. The hydroxyapatite is rod-shaped with an average length of 100 nm, an average diameter of 40 nm, and a specific surface area of ​​>50 m 2 / g, the product brand of hydroxyapatite is CHT TM Type I: The purity of triethyl citrate is ≥99%, it is food grade, and its product brand is MTL Triethyl citrate.

[0054] [Oral Care Products]

[0055] P3HB3HP and hydroxyapatite were dried under vacuum at 90 °C for 5 h;

[0056] A twin-screw extruder (Coperion ZSK-26, L / D = 44) was used. The barrel temperature (from feed port to die) was set to 160°C / 165°C / 170°C / 175°C / 170°C. The screw speed was 200 rpm. Hydroxyapatite was added to the P3HB3HP after preliminary melting through a side feeder. Triethyl citrate was injected into the melting section through a metering pump.

[0057] The extrudate is water-cooled and then pelletized to obtain composite material particles;

[0058] After the composite material particles were vacuum dried at 80°C for 3 h, they were injection molded into standard bars and toothbrush handle samples using an injection molding machine (Haitian MA series) at a mold temperature of 60°C.

[0059] Example 2

[0060] Different from Example 1, the components of this example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 82%, hydroxyapatite 15%, and triethyl citrate 3%.

[0061] Example 3

[0062] Different from Example 1, the components of this example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 84%, hydroxyapatite 15%, and triethyl citrate 1%.

[0063] Example 4

[0064] Different from Example 1, the components of this example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 92%, hydroxyapatite 5%, and triethyl citrate 3%.

[0065] Example 5

[0066] Different from Example 1, the components of this example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 98.5%, hydroxyapatite 1%, and triethyl citrate 0.5%.

[0067] Example 6

[0068] Different from Example 1, the weight average molecular weight Mw of the P3HB3HP copolymer in this example is 1000 kDa.

[0069] Example 7

[0070] Different from the silk in Example 1, the polyhydroxyalkanoate in this example is a P3HB4HB copolymer (4HB4 mol%, Mw 650 kDa).

[0071] Comparative Example 1

[0072] Different from Example 1, the components of this comparative example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 100%.

[0073] Comparative Example 2

[0074] Different from Example 1, the components of this comparative example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 90% and hydroxyapatite 10%.

[0075] Comparative Example 3

[0076] Different from Example 1, the components of this comparative example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 98.5%, triethyl citrate 1.5%.

[0077] Comparative Example 4

[0078] Different from Example 1, the components of this comparative example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 80%, hydroxyapatite 18%, and triethyl citrate 2%.

[0079] Comparative Example 5

[0080] Different from Example 1, the components of this comparative example are: P3HB3HP (3HP 4 mol%, Mw 650 kDa) 85%, hydroxyapatite 10%, and triethyl citrate 5%.

[0081] Performance Testing

[0082] Flexural modulus: tested in accordance with ISO 178.

[0083] 24h Water Absorption: Tested in accordance with ISO 62. The sample, dried to constant weight, is completely immersed in distilled water at 23°C ± 1°C for 24h ± 1h. The sample is then wiped dry and weighed to calculate the percentage of water absorption.

[0084] Charpy notched impact strength: tested according to standard ISO 179-1 method 1eA.

[0085] Test results

[0086] The test results of Examples 1-6 and Comparative Examples 1-5 are shown in Table 1.

[0087] Table 1 Test results of Examples 1-6 and Comparative Examples 1-5

[0088]

[0089]

[0090] As can be seen from Table 1, the composite materials in Examples 1-7 of the present invention not only have low water absorption, but also have high flexural modulus (rigidity) and moderate impact strength (toughness), and can meet the mechanical requirements of oral care products while suppressing absorption.

[0091] Comparing Example 1 with Comparative Example 1, it can be seen that the pure polyhydroxyalkanoate material in Comparative Example 1 has a high water absorption rate and a low flexural modulus, and has the problems of insufficient rigidity and easy water absorption. Comparing Example 1 with Comparative Example 2, it can be seen that although only adding hydroxyapatite can improve the rigidity of the material and inhibit water absorption, the impact strength of the material is 2.8 kJ / m 2 (less than 3kJ / m 2 ), resulting in insufficient toughness of the material, easy brittle fracture, and poor processing performance. Comparative Example 1 and Comparative Example 3 show that when only triethyl citrate is added, the flexural modulus of the material is 1.6GPa (less than 3.2GPa), and the water absorption rate is 1.9% (greater than 1.0%), that is, when only triethyl citrate is added, the rigidity of the material cannot be improved, nor can the water absorption rate of the material be effectively reduced. Comparative Example 1 and Comparative Example 4 show that when the addition amount of hydroxyapatite is too high, the material will be too brittle, so that the impact toughness does not meet the requirements. Comparative Example 1 and Comparative Example 5 show that when the content of triethyl citrate is too high, the polyhydroxyalkanoate will be over-plasticized, resulting in a decrease in the rigidity of the material, which is not conducive to the application of oral care products.

[0092] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the description of the present invention under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A polyhydroxyalkanoate composite material, characterized in that: The invention comprises the following components in percentage by mass: 82%-98.5% of polyhydroxyalkanoate, 1%-15% of hydroxyapatite and 0.5%-3% of triethyl citrate.

2. The polyhydroxyalkanoate composite material according to claim 1, wherein The polyhydroxyalkanoate includes at least one of a P3HB3HP copolymer and a P3HB4HB copolymer.

3. The polyhydroxyalkanoate composite material according to claim 2, wherein In the P3HB3HP copolymer, the content of 3-hydroxypropionate units is 3 mol% to 8 mol%; and / or, In the P3HB4HB copolymer, the content of 4-hydroxybutyrate units is 3 mol% to 8 mol%.

4. The polyhydroxyalkanoate composite material according to claim 2, wherein The weight average molecular weights of the P3HB3HP copolymer and the P3HB4HB copolymer are both 500 kDa-1000 kDa.

5. The polyhydroxyalkanoate composite material according to any one of claims 1 to 4, characterized in that The average particle size of the hydroxyapatite is 20nm-200nm.

6. The polyhydroxyalkanoate composite material according to any one of claims 1 to 4, characterized in that The mass percentage of the hydroxyapatite is 5%-12%; and / or, The mass percentage of the triethyl citrate is 1%-2.5%.

7. An oral care product, characterized in that: The polyhydroxyalkanoate composite material comprises the polyhydroxyalkanoate composite material according to any one of claims 1 to 6.

8. The oral care product according to claim 7, wherein The oral care product includes at least one of a dental floss handle and a toothbrush handle.

9. A method for preparing an oral care product, characterized in that: include: Providing polyhydroxyalkanoate and hydroxyapatite, wherein the water content of the polyhydroxyalkanoate and hydroxyapatite is less than 0.05 wt%; Providing triethyl citrate; The polyhydroxyalkanoate, hydroxyapatite, and triethyl citrate are blended and granulated to obtain composite material particles, wherein the mass percentage of the polyhydroxyalkanoate is 82%-98.5%, the mass percentage of the hydroxyapatite is 1%-15%, and the mass percentage of the triethyl citrate is 0.5%-3%; The composite material particles are processed and formed into oral care products.

10. The method for preparing the oral care product according to claim 9, wherein: The step of blending the polyhydroxyalkanoate, hydroxyapatite and triethyl citrate and then granulating the mixture comprises: The hydroxyapatite and part of polyhydroxyalkanoate or part of triethyl citrate are prepared into master batches, and then blended with the remaining components; or, The polyhydroxyalkanoate and the triethyl citrate are first mixed and melted, and then the hydroxyapatite is added and blended; or, The polyhydroxyalkanoate, hydroxyapatite and triethyl citrate are blended at a rotation speed of 100 rpm to 250 rpm.

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