Heat-resistant transparent polylactic acid composite material for 3D printing and preparation method thereof

Abstract

The invention discloses a heat-resistant transparent polylactic acid composite material for 3D printing and a preparation method of the heat-resistant transparent polylactic acid composite material. The heat-resistant transparent polylactic acid composite material is prepared from the following raw materials in parts by weight: 50-80 parts of polylactic acid and 20-50 parts of polymethyl methacrylate, and the total part number of the two raw materials is 100. And further comprises 0.1-5 parts of a cross-linking agent, 0.1-5 parts of an antioxidant and 0.1-1 part of a lubricant. Molecular chains of a 3D printed piece of the polylactic acid composite material form a three-dimensional network structure, and the transparency and heat resistance of the material are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of polylactic acid composites, and particularly relates to a heat-resistant transparent polylactic acid composite for 3D printing and a preparation method thereof. BACKGROUND

[0002] 3D printing technology, also known as additive manufacturing technology, is a technology that generates a three-dimensional entity by layer-by-layer material addition based on the principle of layer manufacturing. At present, 3D printing technology is mainly applied to product prototyping, mold manufacturing, and artistic creation, jewelry making and other fields, replacing these traditional fine processing processes. In addition, 3D printing technology is gradually applied to the fields of medicine, biological engineering, architecture, clothing, aviation, etc., and has opened up a broad space for innovation.

[0003] 3D printing technology includes a series of different technologies, including selective laser sintering (SLS), stereolithography (SLA), fused deposition modeling (FDM), etc., among which FDM is the most commonly used technology process. The principle is to use thermoplastic polymer materials in a molten state to extrude from the nozzle, solidify into a profile-shaped thin layer, and then add one layer after another to form a product. At present, there are fewer polymer materials used for fused deposition modeling technology on the market, and the most common ones are acrylonitrile-butadiene-styrene terpolymer (ABS), polylactic acid (PLA) and nylon (PA).

[0004] Polylactic acid has good biocompatibility and processing performance, is very widely sourced, and is low in cost. Polylactic acid has good processing performance, chemical inertness, biodegradability, and good biocompatibility. Its degradation occurs under the conditions of industrial composting, and the final degradation product is carbon dioxide and water, which has no pollution to the environment and human body, making it a very promising green thermoplastic polymer material. It has been widely valued and researched in various fields, and has been widely used in biomedical, automotive industry, packaging materials, textile industry and other fields. It is also an ideal 3D printing material.

[0005] However, as a commonly used 3D printing material, polylactic acid has the main defects of high cost, poor toughness, low melt strength, slow crystallization rate, and low crystallinity, which leads to the problems of poor heat resistance (heat distortion temperature HDT≈55℃), low interlayer bonding strength (<3MPa) and unsatisfactory biodegradability of pure PLA as a 3D printing material, which seriously limits its application.

[0006] In order to improve the poor heat resistance and poor interlayer bonding strength of polylactic acid, it is of great significance to study a polylactic acid composite based on 3D printing and a preparation method thereof.

[0007] High melt strength PLA has excellent rheological properties, a wide processing window and stable processing state, which can meet the requirements of various molding processes and help to expand the application field of PLA. In order to fully utilize the development of biodegradable PLA in the field of 3D printing, a large number of researchers have carried out functional modification on PLA. For example, patent documents CN103980683A and CN104530669A use PLA and aliphatic polycarbonate to blend, use peroxide as initiator, and use triallyl isocyanurate (TAIC) and a mixture of GMA-ethylene methyl acrylate terpolymer as crosslinking agent to obtain modified polylactic acid, and then complete the preparation of 3D printing process products, but the transparency of the raw materials used is general, which is difficult to meet the application requirements of high transparency. Patent document CN111234279A uses the method of irradiation crosslinking TAIC multifunctional monomer to improve the method of PLA / PBAT blending system to obtain a film product with excellent water vapor barrier performance, which is used for agricultural mulching film or packaging material, and does not involve the application in the field of 3D printing.

[0008] Patent document CN111187495A discloses a preparation method of high-toughness and high-heat-resistant transparent polylactic acid (PLA) composite material. The core-shell toughening agent S-2001 used is a copolymer of organic silicon and acrylate as the core, and polymethyl methacrylate as the shell; methyl methacrylate (MMA) and glycidyl methacrylate (GMA) copolymer (MG) are used as heat-resistant modifier and compatibilizer; the components of the composite material are as follows in mass percentage: polylactic acid (PLA) 50-80%, core-shell toughening agent S-2001 20%, methyl methacrylate (MMA) and glycidyl methacrylate (GMA) copolymer (MG) 5-30%. However, this document does not involve the transparency of the material, especially the imaging degree (haze), and there is still room for improvement in heat resistance.

[0009] In view of the above status, it is urgent to develop a new kind of 3D printing polylactic acid composite material to meet the needs of practical use. SUMMARY

[0010] The purpose of the present application is to provide a heat-resistant transparent polylactic acid composite material for 3D printing and a preparation method thereof, to solve the problems of poor heat resistance and low interlayer bonding force of PLA 3D printing materials in the prior art.

[0011] In order to achieve the above purpose, the technical scheme of the present application is: The application discloses a heat-resistant transparent polylactic acid composite material for 3D printing, which is prepared from the following raw materials in parts by weight: polylactic acid (PLA) 50-80 parts, polymethyl methacrylate (PMMA) 20-50 parts, wherein the total amount of the two raw materials is 100 parts; and a crosslinking agent 0.1-5 parts, an antioxidant 0.1-5 parts and a lubricant 0.1-1 part. The polylactic acid (PLA) has a melt index (MFI) of 3-10 g / 10 min at 190 DEG C and under a load of 2.16 kg, a glass transition temperature of less than or equal to 60 DEG C, and a melting temperature of 130-155 DEG C, for example, Luminy PLALX175 and LX975 produced by TotalEnergies Corbion. The polymethyl methacrylate (PMMA) has a melt flow rate of 8-15 g / 10 min at 230 DEG C and under a load of 3.8 kg, a 3mm light transmittance of greater than or equal to 92%, a haze of less than or equal to 0.5%, and a heat distortion temperature of greater than or equal to 94 DEG C under a load of 1.8 MPa, for example, PMMA OD01 produced by Wanhua Chemical. The crosslinking agent is at least one of triallyl isocyanurate, trimethallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and triglycidyl triisocyanate. The antioxidant is at least one of a hindered phenolic antioxidant or a phosphite antioxidant. The lubricant is one of stearic acid amide, vinyl bis stearic acid amide, stearic acid monoglyceride and PE wax.

[0012] The application further discloses a preparation method of the heat-resistant transparent polylactic acid composite material for 3D printing. S1, the dry PLA and PMMA are uniformly mixed with the antioxidant and the lubricant in a high-speed stirrer to obtain a premix; S2, the premix is added into a double-screw extruder from a main feeding port, the crosslinking agent is heated to 115-125 DEG C and added into the double-screw extruder from a side feeding port in a liquid injection mode; S3, the heat-resistant transparent polylactic acid composite material is obtained by extruding, cooling, cutting and drying the double-screw extruder, wherein the temperature of the double-screw extruder from the feeding port to the die is 120-210 DEG C, and the drying temperature is 60-70 DEG C.

[0013] The heat-resistant transparent polylactic acid composite material of the present application has good heat resistance and transparency, and can be used as 3D printing consumables for fused deposition modeling (FDM) 3D printing. It can be printed by fused filament fabrication (FFF) method, and also can be directly used for 3D printing (fused granular manufacturing FGF) by using the material particles of the present application to obtain 3D printed parts. The 3D printed parts are industrial parts, temperature-resistant packaging containers or complex structural parts.

[0014] Further preferably, the 3D printed parts obtained from the high-heat-resistant polylactic acid composite material of the present application can be subjected to irradiation processing under the irradiation of an electron beam with a radiation dose of 10-100 kGy, further improving the heat resistance of the 3D printed parts.

[0015] Compared with the prior art, the present application has the following advantages: The PMMA used in the present application has good optical properties and weather resistance. By blending PMMA with PLA, the brittleness and thermal properties of PLA are improved. The obtained composite material combines the high transparency of PMMA and the biodegradability of PLA. By introducing a crosslinking agent and irradiation crosslinking, the compatibility of PMMA and PLA in the composite material is further improved, so that the material has better transparency and processing performance. If electron beam irradiation process is used, the molecular chains of the 3D printed parts of the polylactic acid composite material of the present application can form a three-dimensional network structure, and the transparency and heat resistance of the material are improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The processing process and use characteristics of the present application are shown in the figure. DETAILED DESCRIPTION

[0017] The technical solutions of the present application are described below in detail and completely. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] In the following examples and comparative examples, the polylactic acid is LX175 produced by TotalEnergies Corbion; and the polymethyl methacrylate (PMMA) is PMMA OD01 produced by Wanhua Chemical.

[0019] Example 1 The raw materials and weight parts of the heat-resistant transparent polylactic acid composite material for 3D printing of Example 1 are listed in Table 1, wherein the melt flow rate of PLA is 5 g / 10 min (190℃ / 2.16 kg), the glass transition temperature is <59.5℃; the melting point is 151℃; the melt flow rate of PMMA is 8 g / 10 min; the light transmittance (3 mm) is 93%, the haze is 0.4%; the heat distortion temperature (1.8 MPa) is 94℃; The processing process is as shown in Figure 1 The processing process is as shown in S1, the PLA, PMMA resin dried at 60℃ for 4h, antioxidant, lubricant are uniformly mixed in a high-speed mixer to obtain a premix; S2, the premix is added to the twin-screw extruder from the main feeding port; the crosslinking agent is heated to 120℃, and is added to the twin-screw extruder from the side feeding port by liquid injection; S3, extruded by the twin-screw extruder, cooled, granulated, and dried to obtain a heat-resistant transparent polylactic acid composite material; the temperature of the twin-screw extruder from zone 1 to zone 10 is 120℃, 180℃, 200℃, 200℃, 200℃, 200℃, 200℃, 200℃, 200℃, 180℃, and the die temperature is 180℃; The obtained heat-resistant transparent polylactic acid composite material is irradiated by 3D printing to obtain a printed part, and then irradiated by electron beam irradiation with a radiation dose of 15kGy. The Vicat softening temperature of the part material is 101℃; the light transmittance (3 mm) is 92.5%, and the haze is 0.43%.

[0020] Table 1 Raw material formula of Examples 1-4 and Comparative Examples 1-2 and 4, unit: weight parts Example 2 The raw materials and weight parts of the heat-resistant transparent polylactic acid composite material for 3D printing of Example 2 are listed in Table 1, wherein the melt flow rate of PLA is 4 g / 10 min (190℃ / 2.16 kg), the glass transition temperature is <59.5℃; the melting point is 151℃; the melt flow rate of PMMA is 10 g / 10 min; the light transmittance (3 mm) is 93%, the haze is 0.4%; the heat distortion temperature (1.8 MPa) is 94℃; the preparation method is the same as Example 1. The obtained heat-resistant transparent polylactic acid composite material is irradiated by 3D printing to obtain a printed part, and then irradiated by electron beam irradiation with a radiation dose of 20kGy. The Vicat softening temperature of the part material is 119℃; the light transmittance (3 mm) is 93.5%, and the haze is 0.37%.

[0021] Example 3 The raw materials and weight parts of the heat-resistant transparent polylactic acid composite material for 3D printing of Example 3 are listed in Table 1, wherein the melt flow rate of PLA is 6 g / 10 min (190℃ / 2.16 kg), the glass transition temperature is < 59.5℃, the melting point is 151℃, the melt flow rate of PMMA is 12 g / 10 min, the light transmittance (3 mm) is 93%, the haze is 0.4%, and the heat distortion temperature (1.8 MPa) is 94℃. The preparation method is the same as that of Example 1. The obtained heat-resistant transparent polylactic acid composite material is irradiated and processed by irradiation of an electron beam with an irradiation dose of 10 kGy. The Vicat softening temperature of the material of the product is 116℃, the light transmittance (3 mm) is 94.1%, and the haze is 0.32%.

[0022] Example 4 The raw materials and weight parts of the heat-resistant transparent polylactic acid composite material for 3D printing of Example 4 are listed in Table 1, wherein the melt flow rate of PLA is 3.5 g / 10 min (190℃ / 2.16 kg), the glass transition temperature is < 59.5℃, the melting point is 151℃, the melt flow rate of PMMA is 12 g / 10 min, the light transmittance (3 mm) is 93%, the haze is 0.4%, and the heat distortion temperature (1.8 MPa) is 94℃. The preparation method is the same as that of Example 1. The obtained heat-resistant transparent polylactic acid composite material is irradiated and processed by irradiation of an electron beam with an irradiation dose of 30 kGy. The Vicat softening temperature of the material of the product is 132℃, the light transmittance (3 mm) is 93.2%, and the haze is 0.46%.

[0023] Comparative Example 1 Comparative Example 1 has the same raw materials and preparation process as Example 1, except that there is no PMMA and crosslinking agent in the raw materials, and the 3D printed product of the obtained composite material is irradiated and processed by irradiation of an electron beam with an irradiation dose of 15 kGy.

[0024] Comparative Example 2 Comparative Example 2 has the same raw materials and preparation process as Example 1, except that there is no PMMA and crosslinking agent in the raw materials, and the 3D printed product of the obtained composite material is not irradiated and processed.

[0025] Comparative Example 3 Comparative Example 3 has the same raw materials and preparation process as Example 1, except that no crosslinking agent is added to the raw materials, and the 3D printed product of the obtained composite material is not irradiated and processed.

[0026] Comparative Example 4 Comparative Example 4 has the same raw materials and preparation process as Example 1, except that the 3D printed product of the obtained composite material is not irradiated and processed.

[0027] Detection experiment example The obtained heat-resistant transparent polylactic acid composite materials of Examples 1-4 and Comparative Examples 1-4 were irradiated according to the irradiation dose in the respective examples, and then the light transmittance (3mm) was measured according to ISO 13468; the haze (3mm) was measured according to ISO 14782; and the micro-calc softening temperature (B50) was measured according to ISO 306. The performance results are shown in Table 2.

[0028] Table 2 Test results of Examples 1-4 and Comparative Examples 1-4 As can be seen from Table 2, the PLA, PMMA and crosslinking agent used in the product of the present application have a synergistic effect, and after the electron beam irradiation process, the molecular chain of the heat-resistant transparent polylactic acid composite material for 3D printing of the present application forms a three-dimensional network structure, thereby improving the transparency and heat resistance of the material.

[0029] Compared with Example 1, no crosslinking agent is added in Comparative Examples 1-3, and whether or not irradiation processing is performed, the molecular chain of the composite material cannot form a three-dimensional network structure, resulting in a decrease in light transmittance, an increase in haze, and a sharp decrease in heat resistance (Vicat softening temperature).

[0030] In Comparative Example 4, although there is a crosslinking agent, the 3D printed part of the composite material is not subjected to irradiation processing, the molecular chain cannot form a three-dimensional network structure, resulting in a decrease in light transmittance, an increase in haze, and a decrease in heat resistance (Vicat softening temperature).

[0031] The production process of the present application is simple, can effectively improve the performance of the 3D printing material, and can effectively reduce the environmental pollution caused by the production and use of traditional non-biological and biodegradable 3D printing materials.

Claims

1. A heat-resistant transparent polylactic acid composite for 3D printing, characterized by, The raw materials include 50-80 parts of polylactic acid, 20-50 parts of polymethyl methacrylate, 0.1-5 parts of crosslinking agent, 0.1-5 parts of antioxidant and 0.1-1 part of lubricant.

2. The heat-resistant transparent polylactic acid composite of claim 1, wherein, The polylactic acid has a melt index of 3-10 g / 10 min at 190 DEG C under a load of 2.16 kg, a glass transition temperature of less than or equal to 60 DEG C and a melting temperature of 130-155 DEG C.

3. The heat-resistant transparent polylactic acid composite of claim 1, wherein, The polymethyl methacrylate has a melt flow rate of 8-15 g / 10 min at 230 DEG C under a load of 3.8 kg, a 3 mm light transmittance of more than or equal to 92% and a haze of less than or equal to 0.5%, and a heat distortion temperature of more than or equal to 94 DEG C under a load of 1.8 MPa.

4. The heat-resistant transparent polylactic acid composite of claim 1, wherein, The crosslinking agent is at least one of triallyl isocyanurate, trimethallyl isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and trisglycidyl isocyanurate.

5. The heat-resistant transparent polylactic acid composite of claim 1, wherein, The antioxidant is at least one of hindered phenol antioxidant and phosphite antioxidant, and the lubricant is one of stearamide, vinyl bis stearamide, stearic acid monoglyceride and PE wax.

6. The method for preparing the heat-resistant transparent polylactic acid composite material according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, mixing the dry PLA and PMMA with the antioxidant and lubricant in a high-speed mixer to obtain a premix; S2, feeding the premix into a twin-screw extruder from a main feeding port, and feeding the crosslinking agent into the twin-screw extruder from a side feeding port by liquid injection at a temperature of 115-125 DEG C; S3, extruding, cooling, granulating and drying the product to obtain a heat-resistant transparent polylactic acid composite material, wherein the temperature of the twin-screw extruder from the feeding port to the die is 120-210 DEG C, and the drying temperature is 60-70 DEG C.

7. Use of the heat-resistant transparent polylactic acid composite material according to any one of claims 1 to 5, characterized in that, The product is used as a 3D printing material for fused deposition modeling 3D printing to obtain a 3D printed part.

8. Use of the heat-resistant transparent polylactic acid composite material according to claim 7, characterized in that, The 3D printed part is an industrial part, a temperature-resistant packaging container or a complex structure.

9. Use of the heat-resistant transparent polylactic acid composite material according to claim 7, characterized by The 3D printed part is subjected to irradiation processing by irradiation of an electron beam with a radiation dose of 10-100 kGy.

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