Composite filler and application thereof in preparation of polylactic acid composite material

Abstract

The invention discloses a composite filler and application thereof in preparation of a polylactic acid composite material, and belongs to the field of polylactic acid composite materials. The composite filler comprises silane modified inorganic filler particles and phenylphosphonic acid zinc particles, and the inorganic filler is talcum powder or silicon dioxide; the mass ratio of the zinc phenylphosphonate to the inorganic filler is (1-5): 1. When the composite filler is used as a nucleating agent for preparing the polylactic acid composite material, the crystallization property of polylactic acid can be effectively regulated and controlled, good balance of toughness and heat resistance of the polylactic acid composite material is realized, and the polylactic acid composite material has excellent toughness and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of polylactic acid composite materials technology, and more specifically, to a composite filler and its application in the preparation of polylactic acid composite materials. Background Technology

[0002] Polylactic acid (PLA) is a polyester polymer primarily composed of lactic acid molecules. PLA exhibits excellent biodegradability and biocompatibility. However, due to its molecular structure, PLA possesses high rigidity and brittleness, resulting in poor overall toughness. In terms of mechanical properties, PLA's unnotched simply supported beam impact strength is only 16-18 kJ / m²; its heat resistance, particularly its heat deflection temperature (HDT), is only about 54°C. Therefore, compared to petroleum-based plastics such as polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), PLA is significantly inferior in toughness and heat resistance, greatly limiting its application areas.

[0003] To overcome the limitations of PLA's toughness and heat resistance, existing technologies typically employ the addition of nucleating agents. Organic nucleating agents, such as zinc phenylphosphonate (PPZn), are organometallic phosphonates that have been shown to have a certain heterogeneous nucleation effect on PLA, improving its toughness, but reducing its heat resistance. Inorganic nucleating agents (such as talc and silica) can increase the crystallization rate and crystallinity of PLA, improving its heat resistance, but they introduce rigid particles into the PLA resin, reducing its toughness. Furthermore, directly blending these nucleating agents with PLA cannot achieve both good toughness and heat resistance.

[0004] Therefore, there is an urgent need in this field for a new type of filler that can synergistically improve the toughness and heat resistance of PLA materials. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a composite filler that achieves a good balance between the toughness and heat resistance of PLA composite materials.

[0006] In a first aspect of the present invention, a composite packing is provided, the composite packing comprising: Silane-modified inorganic filler particles, wherein the inorganic filler is talc or silica; Zinc phenylphosphonate granules; The mass ratio of zinc phenylphosphonate to inorganic filler ranges from 1 to 5:1.

[0007] In some embodiments of the first aspect of the present invention, the inorganic filler is talc powder, and the particle size D90 of the talc powder is 6.5~38μm.

[0008] In some embodiments of the first aspect of the present invention, the inorganic filler is silica particles with a particle size D90 of 15~550 nm.

[0009] In some embodiments of the first aspect of the present invention, the particle size D90 of the zinc phenylphosphonate particles is 6.5~19 μm.

[0010] In some embodiments of the first aspect of the present invention, silane modification is performed using a silane coupling agent, said silane coupling agent including KH-550.

[0011] In some embodiments of the first aspect of the present invention, the mass ratio of zinc phenylphosphonate to inorganic filler ranges from 1 to 3:1.

[0012] In some embodiments of the first aspect of the present invention, zinc phenylphosphonate is blended with silane-modified inorganic filler to form a composite filler, wherein the particle size D90 of the composite filler is 13~38μm.

[0013] In a second aspect of the invention, the use of a composite filler according to the first aspect of the invention in the preparation of polylactic acid composite materials is provided.

[0014] In a third aspect of the invention, a method for preparing a polylactic acid composite material is provided, wherein a composite filler according to the first aspect of the invention is added to a polylactic acid raw material, and the ratio of the polylactic acid raw material to the composite filler, calculated by mass parts, is as follows: 100 parts of polylactic acid raw material; 1-4 parts of composite filler.

[0015] In some embodiments of the third aspect of the present invention, the ratio of the polylactic acid raw material to the composite filler is as follows: 100 parts of polylactic acid raw material; 1.5 to 3.5 parts of composite filler.

[0016] The present invention has the following beneficial technical effects compared with the prior art: This invention prepares polylactic acid (PLA) composite materials by compounding silane-modified inorganic fillers with zinc phenylphosphonate to form a composite filler, and adding this composite filler as a nucleating agent to PLA raw materials. This effectively controls the crystallization properties of PLA and successfully solves the problems of decreased toughness caused by adding inorganic fillers alone and decreased heat resistance caused by adding zinc phenylphosphonate alone in the prior art. Thus, a good balance between toughness and heat resistance is achieved in PLA composite materials, giving them both excellent toughness and heat resistance. Attached Figure Description

[0017] Figure 1The images are differential scanning calorimetry (DSC) graphs of polylactic acid composite materials prepared using the composite fillers of Examples 1 to 4 and Comparative Examples 1 to 5.

[0018] Figure 2 The images show X-ray diffraction (XRD) patterns of polylactic acid composite materials prepared using the composite fillers of Examples 1 to 4 and Comparative Examples 1 to 3. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments and exemplary models. These specific descriptions and exemplary models are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention.

[0020] The composite filler of the present invention comprises silane-modified inorganic filler particles and zinc phenylphosphonate particles. In the composite filler of the present invention, the silane-modified inorganic filler can be obtained by modifying talc powder with silane, or by modifying SiO2 with silane. The mass ratio of zinc phenylphosphonate to the inorganic filler ranges from 1 to 5:1, preferably from 1 to 3:1.

[0021] The inorganic filler in this invention is modified with a silane coupling agent. In an exemplary embodiment of this invention, KH-550 (i.e., γ-aminopropyltriethoxysilane) is used.

[0022] In the composite filler of the present invention, when the inorganic filler particles are talc, their particle size D90 can be 6.5~38μm. When the inorganic filler particles are SiO2, their particle size D90 can be 15~550nm.

[0023] In the composite filler of the present invention, the particle size D90 of zinc phenylphosphonate (PPZn) can be 6.5~19 μm.

[0024] In this invention, silane-modified inorganic filler particles and zinc phenylphosphonate particles can be ball-milled to obtain composite filler. After ball milling, the composite filler particles with a particle size D90 of 13~38μm are sieved and then added to polylactic acid raw materials.

[0025] When the composite filler of the present invention is used as a nucleating agent to prepare polylactic acid composite materials, the composite filler is added to the polylactic acid raw material according to the ratio requirements. The ratio of polylactic acid raw material to composite filler is calculated by mass parts as follows: 100 parts of polylactic acid raw material and 1 to 4 parts of composite filler; preferably, 1 to 3.5 parts of composite filler.

[0026] In the polylactic acid (PLA) composite material of the present invention, the crystal growth behavior can be effectively controlled by adding the composite filler of the present invention, thereby controlling the crystallinity and crystal size D of the PLA in the prepared PLA composite material to a suitable range. In a specific embodiment of the present invention, the crystallinity of PLA is 37%~43%, and the crystal size D is 7~10 nm. Excessively large cell size is usually accompanied by excessive crystallinity. Although this can improve the heat resistance of the material, it can easily become a stress concentration point in the presence of rigid inorganic fillers, leading to brittleness and decreased impact toughness.

[0027] The polylactic acid composite material of the present invention can be prepared by injection molding, and the preparation method includes the following steps: 1. Preparation of composite fillers Step 1.1: Surface-modified inorganic fillers Inorganic fillers were surface modified using silane coupling agents to obtain silane-modified inorganic fillers.

[0028] Step 1.2: Preparation of composite filler Zinc phenylphosphonate and silane-modified inorganic filler were mixed evenly at a mass ratio of 1 to 5:1 to obtain a composite filler.

[0029] 2. Preparation of polylactic acid composite materials Step 2.1: PLA Preprocessing The polylactic acid raw material is dried to remove moisture from the polylactic acid resin.

[0030] Step 2.2: Raw material preparation and mixing Polylactic acid (PLA) and composite fillers are blended in the following proportions by weight to form a PLA mixture: 100 parts of polylactic acid; 1 to 4 parts of composite filler.

[0031] Step 2.3: Melt blending, extrusion, and pelletizing The polylactic acid mixture obtained in step 2.2 is melt-blended and then extruded and pelletized by a twin-screw extruder to form polylactic acid mixture particles.

[0032] Step 2.4: Injection Molding The polylactic acid mixture granules obtained in step 2.3 are fed into an injection molding machine for injection molding to obtain polylactic acid composite material products. The temperature of the barrel is set to 170~200℃, the temperature of the mold is set to 110~120℃ to meet the requirements of polylactic acid composite material annealing treatment, the injection pressure is set to about 0.5~0.7Mpa, and the holding time is 30~120 s.

[0033] The injection molding process of this invention can also employ injection molding processes for polylactic acid materials known in the art. Those skilled in the art, understanding the raw material proportions, can determine the specific injection molding process.

[0034] The present invention will be further described in detail below with reference to exemplary embodiments thereof.

[0035] Example 1 The composite filler in this embodiment includes surface-modified inorganic filler talc powder and zinc phenylphosphonate (PPZn) particles. The preparation of the composite filler includes the following steps: Step 1.1: Surface-modified inorganic fillers Select talc powder with an inorganic filler of 800 mesh and a D90 of approximately 17 μm, place it in a vacuum drying oven, and dry it at 120°C for 2 hours until the moisture adsorbed on the surface of the talc powder is removed.

[0036] To prepare a 2wt% KH-550 ethanol solution, talc powder and KH-550 ethanol solution were mixed at a mass ratio of 1:10. Deionized water was added to the mixture at a volume ratio of 1:2. Acetic acid was used to adjust the pH of the mixture to 4 to obtain the mixed solution.

[0037] The mixed solution was ultrasonically dispersed for 30 min (40 kHz, 50% power), and then the precipitate was obtained by centrifugation. The precipitate was dried at 80 °C for 4 h to obtain silanized talc (Talc-KH), i.e. silane-modified talc (Talc-KH).

[0038] Step 1.2: Preparation of composite filler PPZn particles with a particle size D90 of approximately 13 μm were selected and weighed together with the silanized talc powder Talc-KH obtained in step 1.1 at a mass ratio of 7:3. The mixture was placed in a zirconia ball mill jar and ball-milled at 300 rpm for 2 hours. After ball milling, the filler was sieved (400 mesh) and dried at 60℃ for 2 hours to prepare a uniformly dispersed PPZn@Talc composite filler with a particle size D90 of 28 μm.

[0039] The following describes the use of PPZn@Talc composite filler in the preparation of polylactic acid composite materials. The preparation steps are as follows: Step 2.1: PLA Preprocessing Polylactic acid: 4023D L-polylactic acid from Nature Works, USA, was selected, with a particle size D90 of approximately 3 mm.

[0040] Place the PLA resin in an oven and dry it at 80°C for 4-6 hours to remove moisture from the raw material and prevent hydrolysis and degradation during processing.

[0041] Step 2.2: Raw material preparation and mixing The raw materials of the polylactic acid composite material in this embodiment are calculated by mass parts and the formulation is as follows: 100 parts of polylactic acid; One part of the PPZn@Talc composite filler prepared in step 1.2.

[0042] Weigh out polylactic acid and PPZn@Talc composite filler according to the above ratio, and mix the two raw materials to form a raw material mixture.

[0043] Step 2.3: Melt blending, extrusion, and pelletizing The raw material mixture obtained in step 2.2 was added to a twin-screw extruder for melt blending. The temperatures of each zone of the extruder were set as follows: 130℃ in the feeding zone, 170℃ in the compression zone, and 180℃ in the homogenization zone. The screw speed was set to 40 rpm to ensure that the material was fully melted. The extruded molten material was rapidly solidified by an air-cooled conveying system and then pelletized to finally obtain polylactic acid composite material particles with a particle size of 3~5 mm.

[0044] Step 2.4: Injection Molding The polylactic acid (PLA) composite material granules obtained after extrusion and pelletizing are fed into an injection molding machine for injection molding. During injection molding, the barrel temperature is set to 190℃ and the mold temperature to 115℃ to meet the requirements for annealing of the PLA composite material. The annealing time is 60 seconds, after which the mold is opened and the sample is removed, producing a PLA composite material sample. Different mold shapes are selected according to the subsequent testing items. For example, a cuboid mold with dimensions of 80 mm × 10 mm × 4 mm is used for unnotched impact strength testing and thermal stress deformation temperature testing; a circular mold with a diameter of 50 mm and a thickness of 1 mm is used for samples used for DSC, infrared, and XRD testing.

[0045] Example 2 The only difference between the composite filler in Example 2 and that in Example 1 is that the mass ratio of PPZn particles to silanized talc powder Talc-KH is 5:3, and the other preparation steps of the PPZn@Talc composite filler are the same as those in Example 1.

[0046] The preparation steps for preparing polylactic acid composite material using PPZn@Talc composite filler in Example 2 are the same as those in Example 1. The polylactic acid composite material sample of Example 2 was obtained by injection molding.

[0047] Example 3 Example 3 uses the same PPZn@Talc composite filler as Example 1. The only difference from Example 1 is the raw material ratio of the polylactic acid composite material. Calculated by mass parts, the raw material ratio of the polylactic acid composite material in this example is as follows: 100 parts of polylactic acid; Three parts of PPZn@Talc composite filler.

[0048] The preparation steps for polylactic acid composite materials using PPZn@Talc composite filler are the same as in Example 1, and the polylactic acid composite material sample of Example 3 is obtained by injection molding.

[0049] Example 4 The only difference between the composite filler in Example 4 and that in Example 1 is that the inorganic filler talc is replaced with SiO2 with a particle size D90 of 105 nm. The surface silane modification treatment of SiO2 is the same as that of talc in Example 1. The silane-modified SiO2 is mixed with PPZn particles to form PPZn@SiO2 composite filler, wherein the mass ratio of PPZn to SiO2 is also 7:3. The preparation of PPZn@SiO2 composite filler is the same as that in Example 1.

[0050] The preparation steps for polylactic acid composite materials using the PPZn@SiO2 composite filler in Example 4 are the same as those in Example 1. The polylactic acid composite material sample of Example 4 is obtained by injection molding.

[0051] To further demonstrate the technical effects of the present invention, comparative examples 1 to 6 are provided below to contrast with the embodiments of the present invention.

[0052] Comparative Example 1: PPZn / PLA composite material The difference between Comparative Example 1 and Example 1 lies in the filler. Comparative Example 1 uses only PPZn from Example 1 as a filler to modify PLA, without adding any inorganic filler. The raw material ratio of the polylactic acid composite material in Comparative Example 1, calculated by mass parts, is: 100 parts of polylactic acid; PPZn 1 copy.

[0053] The other preparation steps of the polylactic acid composite material of Comparative Example 1 were the same as those of Example 1. The polylactic acid composite material PPZn / PLA sample of Comparative Example 1 was obtained by injection molding.

[0054] Comparative Example 2: Talc-KH / PLA composite material

[0055] The difference between Comparative Example 2 and Example 1 lies in the filler. Comparative Example 2 only uses silanized talc (Talc-KH) as described in Example 1 to modify PLA, without adding PPZn. The raw material ratio of the polylactic acid composite material in Comparative Example 2, calculated by mass parts, is: 100 parts of polylactic acid; Talc-KH 1 serving.

[0056] The other preparation steps of the polylactic acid composite material of Comparative Example 2 were the same as those of Example 1. The polylactic acid composite material Talc-KH / PLA sample of Comparative Example 2 was obtained by injection molding.

[0057] Comparative Example 3: SiO2-KH / PLA composite material The difference between Comparative Example 3 and Example 4 lies in the filler. Comparative Example 3 only used silanized silica (SiO2-KH) as described in Example 4 to modify PLA, without adding PPZn. The raw material ratio of the polylactic acid composite material in Comparative Example 3, calculated by mass parts, is: 100 parts of polylactic acid; 1 part of SiO2-KH.

[0058] The other preparation steps of Comparative Example 3 were the same as those of Example 4, and the polylactic acid composite material SiO2-KH / PLA sample of Comparative Example 3 was obtained by injection molding.

[0059] Comparative Example 4: PPZn / Talc / PLA composite material The only difference between Comparative Example 4 and Example 1 is that the talc powder Talc in the composite filler was not modified with silane.

[0060] The other preparation steps of the polylactic acid composite material of Comparative Example 4 were the same as those of Example 1. The polylactic acid composite material PPZn / Talc / PLA sample of Comparative Example 4 was obtained by injection molding.

[0061] Comparative Example 5: PPZn / SiO2 / PLA composite material The only difference between Comparative Example 5 and Example 4 is that the silica (SiO2) in the composite filler was not modified with silane.

[0062] The other preparation steps of the polylactic acid composite material of Comparative Example 5 were the same as those of Example 4. The polylactic acid composite material PPZn / SiO2 / PLA sample of Comparative Example 5 was obtained by injection molding.

[0063] Comparative Example 6: PLA material The difference between Comparative Example 6 and Example 1 is that no filler was added to the polylactic acid raw material, namely, Talc-KH, SiO2-KH, and PPZn were added. The preparation steps of the polylactic acid material of Comparative Example 6 were the same as those of Example 1, and the polylactic acid material sample of Comparative Example 6 was obtained by injection molding.

[0064] To further demonstrate the beneficial technical effects of the present invention, the crystallization properties, thermal stability, and mechanical properties of the polylactic acid composite materials prepared in the specific embodiments and comparative examples of the present invention will be tested and compared below, including: differential scanning calorimetry (DSC), X-ray diffraction (XRD), impact strength, and heat distortion temperature (HDT) tests.

[0065] 1. Differential Scanning Calorimetry (DSC) Differential scanning calorimetry (DSC) was used to perform differential scanning calorimetry (DSC) tests on the polylactic acid composite material samples prepared in Examples 1 to 4 and Comparative Examples 1 to 5. The specific test methods are as follows: Take 5-8 mg of the sample and place it in an aluminum crucible. Under a nitrogen atmosphere, heat the sample from room temperature to 190 °C at a heating rate of 10 °C / min and record the heating curve.

[0066] To evaluate the crystallinity of polylactic acid composite samples, the crystallinity (Xc) of the samples was calculated using the following formula:

[0067] Where: ΔH cc It is the enthalpy of cold crystallization, measured in J / g; ΔH m It is the enthalpy of fusion, in J / g; f is the mass fraction of PLA; ΔH 100 It is the enthalpy of fusion of 100% pure PLA crystals, with a value of 93.6 J / g.

[0068] The test results are shown in Table 1 and Figure 1 As shown.

[0069] Table 1. DSC test results of samples from Examples 1 to 4 and Comparative Examples 1 to 5

[0070] In Table 1, T g It is the glass transition temperature, T m It is the melting temperature, ΔH m It is the enthalpy of fusion, X c It refers to crystallinity.

[0071] By comparing Table 1 and Figure 1 The DSC tests of Examples 1 to 4 and Comparative Examples 1 to 5 show that, compared with the composite fillers formed by inorganic fillers without silane modification and PPZn (such as Comparative Examples 4 and 5), the composite fillers formed by silane modification of inorganic filler particles and PPZn in Examples 1 to 4 of the present invention can effectively improve the crystallinity of polylactic acid and control it within a suitable range. The crystallinity Xc range of Examples 1 to 4 is 37% to 43%. Combined with the test data of impact toughness and heat distortion temperature (HDT) described below, it can be seen that the crystallinity controlled by Examples 1 to 4 of the present invention can achieve an effective balance between toughness and heat resistance, so that the polylactic acid composite material has both excellent toughness and heat resistance.

[0072] Compared to the polylactic acid (PLA) composites of Comparative Examples 1 to 6, the PLA composites prepared using the composite fillers of Examples 1 to 4 of this invention achieve an effective balance between toughness and heat resistance. Specifically, the PLA composites prepared using the composite fillers of Examples 1 to 4 of this invention achieve a good balance between toughness and heat resistance compared to using silane-modified inorganic fillers Talc or SiO2 alone (as in Comparative Examples 2 or 3) or using organic fillers PPZn alone (as in Comparative Example 1). Furthermore, compared to composite fillers formed by unmodified inorganic fillers and PPZn (as in Comparative Examples 4 and 5), the composite fillers formed by silane-modified inorganic fillers and PPZn in this invention achieve a good balance between toughness and heat resistance in PLA composites, giving the PLA composites both excellent toughness and heat resistance.

[0073] 2. X-ray diffraction (XRD) test X-ray diffraction (XRD) was performed on polylactic acid (PLA) composite material samples prepared in Examples 1 to 4 and Comparative Examples 1 to 3. The specific testing method is as follows: A block sample with a length and width slightly less than 2 cm (approximately 1.7–1.9 cm) and a thickness of 1 mm was taken and tested using a Rigaku D / MAX2500VL / PC rotating target XRD system (Japan), with a Cu radiation source (λ = 1.5406 Å). The scanning range was 5°–80°, and the scanning speed was 8° / min. The XRD patterns are shown below. Figure 2 As shown.

[0074] based on Figure 2 The XRD patterns of the sample were analyzed, and the lattice parameters of the main diffraction peak near 16.5° were quantitatively analyzed using the Scherrer formula, as follows:

[0075] in: D is the average grain size perpendicular to the direction of the diffraction plane; K is the Scherrer constant, usually taken as 0.9; λ is the wavelength of the X-ray, with a value of 0.154 nm; β is the full width at half maximum (FWHM) of the measured diffraction peak; θ is the Bragg angle.

[0076] The test analysis results are shown in Table 2.

[0077] Table 2. XRD test results of samples from Examples 1 to 4 and Comparative Examples 1 to 3

[0078] By comparing the crystal sizes of Examples 1 to 4 and Comparative Examples 1 to 3 in Table 2, it can be seen that, compared to using silane-modified inorganic fillers Talc or SiO2 alone (as in Comparative Examples 2 and 3) or using organic fillers PPZn alone (as in Comparative Example 1), the polylactic acid crystal size D prepared using the composite fillers of Examples 1 to 4 of this invention is optimized to the range of 7-10 nm. Combined with the impact toughness and heat distortion temperature (HDT) test data described below, it can be seen that in Examples 1 to 4 of this invention, controlling the polylactic acid crystal size D to 7-10 nm achieves a good balance between toughness and heat resistance, giving the polylactic acid composite material both excellent toughness and heat resistance.

[0079] 3. Impact strength and heat distortion temperature (HDT) test According to GB / T 1043.2-2018 standard "Determination of Impact Properties of Simply Supported Beams of Plastics - Part 2: Instrumented Impact Testing", the unnotched impact strength of polylactic acid composite material samples prepared in Examples 1 to 4 and Comparative Examples 1 to 6 was tested. The dimensions of the test specimens were all 80±2 mm in length, 10.0±0.2 mm in width, and 4.0±0.2 mm in thickness. The pendulum energy of the impact testing machine was 4 J, and the support span was 58 mm. Five valid specimens were tested in each group, and the average value of the test results was taken.

[0080] According to GB / T 1634.2—2019 "Determination of Deflection Temperature of Plastics under Load - Part 2: Plastics and Hard Rubber", for polylactic acid composite material samples prepared in Examples 1 to 4 and Comparative Examples 1 to 6, the temperature was increased from room temperature at a rate of 120℃ / min under a constant bending stress of 0.45 MPa. The test was stopped when the sample reached its standard deflection, and the heat distortion temperature of the sample was recorded. Three valid samples were tested in each group, and the average value of the test results was taken.

[0081] The test results for impact strength and heat distortion temperature are shown in Table 3.

[0082] Table 3. Impact strength and heat distortion temperature test results of samples from Examples 1 to 4 and Comparative Examples 1 to 6

[0083] By comparing the impact strength and heat distortion temperature (HDT) of Examples 1 to 4 and Comparative Examples 1 to 6 in Table 3, it can be seen that, compared with the polylactic acid (PLA) composite materials of Comparative Examples 1 to 6, the PLA composite materials prepared using the composite fillers of Examples 1 to 4 of the present invention achieve an effective balance between toughness and heat resistance. Specifically, the PLA composite materials prepared using the composite fillers of Examples 1 to 4 of the present invention achieve an effective balance between toughness and heat resistance compared with using only silane-modified inorganic fillers Talc or SiO2 (as in Comparative Examples 2 and 3) or only organic fillers PPZn (as in Comparative Example 1). Furthermore, compared with the composite fillers formed by unmodified inorganic fillers and PPZn (as in Comparative Examples 4 and 5), the composite fillers formed by modifying inorganic fillers with silane and PPZn in the present invention can better achieve a balance between toughness and heat resistance in PLA composite materials, giving PLA composite materials both excellent toughness and heat resistance.

[0084] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the term "comprising" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention and should not be used to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments or equivalent substitutions can be made to some of the technical features without departing from the essence and scope of the present invention. Such modifications or equivalent substitutions still fall within the scope of the present invention.

Claims

1. A composite filler, characterized in that, The composite filler includes: Silane-modified inorganic filler particles, wherein the inorganic filler is talc or silica; Zinc phenylphosphonate granules; The mass ratio of zinc phenylphosphonate to inorganic filler ranges from 1 to 5:

1.

2. The composite filler as described in claim 1, wherein, The inorganic filler is talc powder, and the particle size D90 of the talc powder is 6.5~38μm.

3. The composite filler as described in claim 1 or 2, wherein, The inorganic filler is silica particles with a particle size D90 of 15~550nm.

4. The composite filler as described in claim 3, wherein, The particle size D90 of zinc phenylphosphonate particles is 6.5~19μm.

5. The composite filler as described in claim 1, wherein, Silane modification is performed using a silane coupling agent, wherein the silane coupling agent includes KH-550.

6. The composite filler as described in claim 4, wherein, The mass ratio of zinc phenylphosphonate to inorganic filler ranges from 1 to 3:

1.

7. The composite filler as described in claim 1, wherein, Zinc phenylphosphonate is blended with silane-modified inorganic filler to form a composite filler, wherein the particle size D90 of the composite filler is 13~38μm.

8. The use of the composite filler as described in any one of claims 1 to 7 in the preparation of polylactic acid composite materials.

9. A method for preparing a polylactic acid composite material, characterized in that, The composite filler as described in any one of claims 1 to 7 is added to the polylactic acid raw material, and the ratio of the polylactic acid raw material to the composite filler, calculated by mass parts, is as follows: 100 parts of polylactic acid raw material; 1-4 parts of composite filler.

10. The preparation method according to claim 9, wherein, The ratio of the polylactic acid raw material to the composite filler, calculated by parts by weight, is as follows: 100 parts of polylactic acid raw material; 1 to 3.5 parts of composite filler.

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