Polylactic acid composite material as well as preparation method and application thereof

Abstract

The invention discloses a polylactic acid composite material as well as a preparation method and application thereof, and belongs to the field of high polymer materials. According to the present invention, the use amounts of the PLA, the talcum powder, the PBS and the PBAT are selected to be within the specific range, and the Tx-Tg of the obtained composite material is further controlled to be within the specific range, such that the material has excellent extrusion stability, and is suitable for application in the fields of tableware and the like.

Description

Technical Field

[0001] The present application relates to the field of polymer materials, and particularly relates to a polylactic acid composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Polylactic acid (PLA) is a thermoplastic aliphatic polyester with a glass transition temperature of about 60°C. It is a hard material in the glassy state at room temperature, and its thermal properties are similar to those of polystyrene. PLA can be subjected to various forming processes, such as extrusion, cast film forming, blown film forming, injection molding, blow molding, fiber forming, etc. However, the extrusion stability of polylactic acid is poor. Therefore, how to improve the extrusion stability of polylactic acid is a technical problem that must be solved in expanding the application of polylactic acid in the fields of food utensils and the like. Summary of the Invention

[0003] Based on the defects existing in the prior art, the purpose of the present application is to provide a polylactic acid composite material, a preparation method thereof, and an application thereof, aiming to enable the polylactic acid composite material to have excellent extrusion stability and be suitable for applications in the fields of food utensils and the like.

[0004] To achieve the above purpose, in the first aspect, the present application provides a polylactic acid composite material, which comprises the following components in parts by weight:

[0005]

[0006] The polylactic acid composite material satisfies: 280°C ≤ T x - T g ≤ 310°C,

[0007] wherein, T x is the initial decomposition temperature of the polylactic acid composite material, with the unit of °C,

[0008] T g is the glass transition temperature of the polylactic acid composite material, with the unit of °C.

[0009] T x - T g reflects the thermal stability and molecular chain flexibility of the polylactic acid composite material, directly affecting its processing stability. By controlling T x - T g within the above suitable range, ensuring that it has good thermal stability and molecular chain flexibility, and thus having excellent extrusion stability. T x - T g depends on the PLA content, talc powder content, PBS (i.e., polybutylene succinate) content, PBAT (i.e., polybutylene adipate terephthalate) content, terminal carboxyl group content of PLA, terminal carboxyl group content of PBS, and terminal carboxyl group content of PBAT, etc.

[0010] By selecting the amounts of PLA, talcum powder, PBS, and PBAT within the above - specified ranges and further controlling the T of the resulting composite material x -T g within the above - specified ranges, the material has excellent extrusion stability and is suitable for applications in fields such as food utensils.

[0011] The amount of the polylactic acid is in the range of 39 - 91 parts by weight, such as an interval range formed by any two values among 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight or more.

[0012] The amount of the talcum powder is in the range of 5 - 40 parts by weight, such as an interval range formed by any two values among 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight or more.

[0013] The amount of the polybutylene succinate is in the range of 1 - 20 parts by weight, such as an interval range formed by any two values among 1 part by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 17 parts by weight, 20 parts by weight or more.

[0014] The amount of the poly(butylene adipate - co - terephthalate) is in the range of 5 - 15 parts by weight, such as an interval range formed by any two values among 5 parts by weight, 7 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight or more.

[0015] T x -T g is in the range of 280 °C - 310 °C, such as an interval range formed by any two values among 280 °C, 285 °C, 290 °C, 295 °C, 300 °C, 305 °C, 310 °C or more.

[0016] Preferably, the T x is 330 °C - 360 °C. The T x can be selected as an interval range formed by any two values among 330 °C, 335 °C, 340 °C, 345 °C, 350 °C, 355 °C, 360 °C or more.

[0017] Preferably, the T g is 50 °C - 60 °C. The T g can be selected as an interval range formed by any two values among 50 °C, 52 °C, 54 °C, 56 °C, 58 °C, 60 °C or more.

[0018] T xIt can be measured according to the following method: Using a TG209 thermogravimetric analyzer from NETZCH company, measure the thermogravimetric TG curve of a 10 mg sample under a nitrogen atmosphere. The temperature corresponding to the intersection of the tangent line of the descending section of the TG curve and the baseline is the initial decomposition temperature T x , where the heating rate is 10 °C / min.

[0019] T g It can be measured according to the following method: Conduct on a DSC204 thermal analyzer from Netzsch company in Germany, with nitrogen protection. A sample with a mass of 5 ± 1 mg is first heated from 30 °C to 160 °C at a heating rate of 10 °C / min and held at 160 °C for 3 min, then cooled to 110 °C at a rate of 20 °C / min, and then heated to 150 °C at a rate of 10 °C / min. The glass transition temperature Tg of the sample is taken from the curve of the second heating. The temperature corresponding to the intersection of the extrapolated line at the turning point and the baseline is the glass transition temperature Tg.

[0020] Preferably, the terminal carboxyl group content of the polybutylene terephthalate adipate is 10 - 20 mol KOH / t. Controlling the terminal carboxyl group content of the polybutylene terephthalate adipate within the range of 10 - 20 mol KOH / t, such as 10 mol KOH / t, 12 mol KOH / t, 14 mol KOH / t, 16 mol KOH / t, 18 mol KOH / t, 20 mol KOH / t or the range formed by any two of the above values, the melt stability of the polylactic acid composite material during the extrusion process is better, thus making the extrusion stability better.

[0021] Preferably, the terminal carboxyl group content of the polybutylene succinate is 15 - 35 mol KOH / t. Controlling the terminal carboxyl group content of the polybutylene succinate within the range of 15 - 35 mol KOH / t, such as 15 mol KOH / t, 17 mol KOH / t, 20 mol KOH / t, 22 mol KOH / t, 24 mol KOH / t, 26 mol KOH / t, 28 KOH / t, 30 KOH / t, 32 KOH / t, 35 KOH / t or the range formed by any two of the above values, the melt stability of the polylactic acid composite material during the extrusion process is better, thus making the extrusion stability better.

[0022] Preferably, the carboxyl end group content of the polylactic acid is 10 to 30 mol KOH / t. By controlling the carboxyl end group content of the polylactic acid within the range of 10 to 30 mol KOH / t, such as 10 KOH / t, 12 KOH / t, 15 mol KOH / t, 17 mol KOH / t, 20 mol KOH / t, 22 mol KOH / t, 24 mol KOH / t, 26 mol KOH / t, 28 KOH / t, 30 KOH / t or any range formed by any two of the above values, the melt stability of the polylactic acid composite material during the extrusion process is better, and the extrusion stability is better.

[0023] The carboxyl end group content of the polybutylene terephthalate adipate, the carboxyl end group content of the polybutylene succinate, and the carboxyl end group content of the polylactic acid can all be measured according to the following method: using an ortho-cresol-chloroform mixed solution as a solvent, the mass ratio of ortho-cresol to chloroform in the solvent is 7:3, and a Metrohm Titrino series automatic potentiometric titrator is used to test the carboxyl end group value, and the test method is carried out in accordance with the standard FZ / T 50012-2006 "Determination of Carboxyl End Group Content in Polyester - Titrimetric Analysis Method".

[0024] Preferably, the polylactic acid includes at least one of L-polylactic acid and D-polylactic acid.

[0025] Preferably, the intrinsic viscosity of the polylactic acid is 0.9 to 1.5 dL / g. For example, the intrinsic viscosity of the polylactic acid is 0.9 dL / g, 1.0 dL / g, 1.1 dL / g, 1.2 dL / g, 1.3 dL / g, 1.4 dL / g, 1.5 dL / g or any range formed by any two of the above values.

[0026] When the intrinsic viscosity of the polylactic acid is within the range of 0.9 to 1.5 dL / g, the extrusion stability of the obtained material is better.

[0027] The intrinsic viscosity of the polylactic acid can be measured according to the following method: at 25 °C, accurately weigh 0.1250 ± 0.0005 g of the sample and dissolve it in 25 mL of a solution (mass ratio of o-dichlorobenzene:phenol = 2:3), heat and stir at 110 °C until the resin is completely dissolved, and measure with a viscometer, and the viscosity value is retained to two decimal places.

[0028] Preferably, the intrinsic viscosity of the polybutylene succinate is 1.4 to 1.8 dL / g. For example, the intrinsic viscosity of the polybutylene succinate is 1.4 dL / g, 1.5 dL / g, 1.6 dL / g, 1.7 dL / g, 1.8 dL / g or any range formed by any two of the above values.

[0029] When the intrinsic viscosity of the polybutylene succinate is in the range of 1.4 to 1.8 dL / g, the extrusion stability of the resulting material is better.

[0030] The intrinsic viscosity of the polylactic acid can be measured by the following method: At 25°C, accurately weigh 0.1250 ± 0.0005 g of the sample and dissolve it in 25 ml of a solution (o-dichlorobenzene:phenol = 2:3 mass ratio). Heat and stir at 110°C until the resin is completely dissolved, and measure with a viscometer. Keep the viscosity value to two decimal places.

[0031] Preferably, the molar amount of adipic acid in the polybutylene adipate terephthalate is 70% to 100% of the molar amount of terephthalic acid. For example, the molar amount of adipic acid in the polybutylene adipate terephthalate is 70%, 75%, 80%, 85%, 90%, 95%, 100% or any range formed by any two of the above values.

[0032] The molar ratio of adipic acid to terephthalic acid in the polybutylene adipate terephthalate can be measured by the following method: Through 1 H NMR test, using deuterated chloroform as the solvent and TMS as the internal standard, the results are calculated according to the following formula: 1 The peak area at 8.1 ppm in the 1H NMR spectrum represents the molar ratio content of terephthalic acid, 1 The peak area at 2.3 ppm in the 1H NMR spectrum represents the molar ratio content of adipic acid. Calculate their molar ratio based on the molar ratio content of adipic acid to terephthalic acid.

[0033] Preferably, the intrinsic viscosity of the polybutylene adipate terephthalate is 1.2 to 1.6 dL / g. For example, the intrinsic viscosity of the polybutylene adipate terephthalate is 1.2 dL / g, 1.25 dL / g, 1.3 dL / g, 1.35 dL / g, 1.4 dL / g, 1.45 dL / g, 1.5 dL / g, 1.55 dL / g, 1.6 dL / g or any range formed by any two of the above values.

[0034] When the intrinsic viscosity of the polybutylene adipate terephthalate is in the range of 1.2 to 1.6 dL / g, the extrusion stability of the resulting material is better.

[0035] The intrinsic viscosity of the polybutylene adipate terephthalate can be measured by the following method: At 25°C, accurately weigh 0.1250 ± 0.0005 g of the sample and dissolve it in 25 mL of a solution (o-dichlorobenzene:phenol = 2:3 mass ratio). Heat and stir at 110°C until the resin is completely dissolved, and measure with a viscometer. Keep the viscosity value to two decimal places.

[0036] Preferably, the particle size D95 of the talcum powder satisfies 10 μm ≤ D95 ≤ 30 μm. For example, the particle size D95 of the talcum powder is 10 μm, 12 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 27 μm, 30 μm or the range formed by any two of the above values.

[0037] The test method for the particle size D95 of the talcum powder can be determined with reference to the method of "Particle Size Analysis - Laser Diffraction Method" in GB / T 19077.1 - 2008.

[0038] Preferably, the mass fraction of the polylactic acid in the polylactic acid composite material is more than 30%, such as 30%, 40%, 50%, 60%, 70%, 80%, 89% or the range formed by any two of the above values.

[0039] In a second aspect, the present application provides a method for preparing the polylactic acid composite material, including the following steps: mixing and dispersing all raw materials, melt - extruding, and pelletizing to obtain the polylactic acid composite material, wherein the melt - extrusion temperature is 160°C to 200°C.

[0040] Preferably, the melt - extrusion is carried out in a twin - screw extruder, the ratio of the length to the diameter of the twin - screw extruder is (35 - 55):1, and the screw rotation speed is 500 - 800 r / min.

[0041] In a third aspect, the present application further provides the application of the polylactic acid composite material in food utensils (such as knives, forks, spoons, dinner plates, lunch boxes, straws, etc.).

[0042] In a fourth aspect, the present application further provides a straw, and the material of the straw includes the polylactic acid composite material.

[0043] In some embodiments, the method for preparing the straw includes the following steps: extruding the polylactic acid composite material on a single - screw extruder, cutting the tube, and cooling, wherein the extrusion temperature is 140°C to 190°C, the extrusion speed is 30 kg / h to 80 kg / h, the straw weight per piece is 2.0 g / piece to 2.9 g / piece, and the cooling temperature is 20°C to 40°C.

[0044] Compared with the prior art, the beneficial effects of the present application are as follows: By selecting the dosages of PLA, talcum powder, PBS, and PBAT within a specific range, and further controlling the T x -T g within a specific range, the obtained material has excellent extrusion stability and is suitable for applications in fields such as food utensils. Detailed Embodiments

[0045] To better illustrate the purpose, technical solution and advantages of the present application, the present application will be further described below in conjunction with specific embodiments and comparative examples. The purpose is to understand the content of the present application in detail, rather than a limitation to the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application. The experimental reagents and instruments involved in the implementation of the present application are all common ordinary reagents and instruments unless otherwise specified. In the present application, among the technically characterized described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0046] The following examples and comparative examples each provide a polylactic acid composite material. The formulations of these polylactic acid composite materials are shown in Tables 1 and 2, and their preparation methods include the following steps: Mix all the raw materials and disperse them, then feed them into a twin-screw extruder, granulate to obtain the polylactic acid composite material;

[0047] Among them, the length-diameter ratio of the screw of the twin-screw extruder is 40:1, the screw rotation speed is 700 r / min, and the melting and mixing temperature is 190 °C.

[0048] The raw material information used in the above examples and comparative examples is as follows, and unless otherwise specified, they are all commercially available raw materials. In addition, the component raw materials used in each parallel experiment are all of the same kind:

[0049] PLA1: Model PLA 3001D, manufacturer NATUREWORKS, carboxyl end group content 20 mol KOH / t, intrinsic viscosity 1.24 dL / g;

[0050] PLA2: Model PLA 4032D, manufacturer NATUREWORKS, carboxyl end group content 10 mol KOH / t, intrinsic viscosity 1.45 dL / g;

[0051] PLA3: Model PLA 3251D, manufacturer NATUREWORKS, carboxyl end group content 30 mol KOH / t, intrinsic viscosity 0.99 dL / g;

[0052] PLA 4: Model PLAFY801, manufacturer Anhui Fengyuan, carboxyl end group content 7 mol KOH / t, intrinsic viscosity 1.43 dL / g;

[0053] PLA 5: Model PLA FY604, manufacturer Anhui Fengyuan, carboxyl end group content 35 mol KOH / t, intrinsic viscosity 1.35 dL / g;

[0054] PBS1: Model A200NC801, manufacturer Zhuhai Jinfa Biology, carboxyl end group content 25 mol KOH / t, intrinsic viscosity 1.60 dL / g;

[0055] PBS2: Model PBS E810, manufacturer Meirui New Materials, terminal carboxyl content 15 mol KOH / t, intrinsic viscosity 1.58 dL / g;

[0056] PBS 3: terminal carboxyl content 35 mol KOH / t, intrinsic viscosity 1.62 dL / g, the preparation method thereof is as follows: 1,4-butanediol and succinic acid are subjected to esterification reaction at a molar ratio of 1.3:1 at 250°C for 3 hours, and then tetrabutyl titanate catalyst and triphenyl phosphate stabilizer are added, based on the mass of the polycondensation product as 100wt%, the amount of tetrabutyl titanate catalyst is 0.3wt%, and the amount of triphenyl phosphate stabilizer is 0.03wt%, and the polycondensation reaction is carried out at 250°C for 4 hours to obtain PBS 3;

[0057] PBS 4: terminal carboxyl content 10 mol KOH / t, intrinsic viscosity 1.62 dL / g, its preparation method is different from PBS 3 in that the amount of catalyst tetrabutyl titanate used is 0.5 wt%;

[0058] PBS 5: Model BG-2112, manufacturer Xuelang Biotechnology Co., Ltd., terminal carboxyl content 40 mol KOH / t, intrinsic viscosity 1.55 dL / g;

[0059] PBAT 1: Model A400NC801, manufacturer Zhuhai Kingfa Biotechnology, terminal carboxyl content 15 mol KOH / t, intrinsic viscosity 1.45 dL / g, adipic acid molar amount is 97.0% of terephthalic acid molar amount;

[0060] PBAT 2: Homemade, terminal carboxyl content 10 mol KOH / t, intrinsic viscosity 1.33 dL / g, adipic acid molar amount is 92.2% of terephthalic acid molar amount;

[0061] PBAT 3: Model TH801T, manufacturer Lanshan Tunhe, terminal carboxyl content 20 mol KOH / t, intrinsic viscosity 1.42 dL / g, adipic acid molar amount is 90.9% of terephthalic acid molar amount;

[0062] PBAT 4: Homemade, terminal carboxyl content 7 mol KOH / t, intrinsic viscosity 1.45 dL / g, adipic acid molar amount is 91.6% of terephthalic acid molar amount;

[0063] PBAT 5: Model HF101, manufacturer Huafeng, terminal carboxyl content 25 mol KOH / t, intrinsic viscosity 1.45 dL / g, adipic acid molar amount is 91.6% of terephthalic acid molar amount;

[0064] Talc is obtained from the following sources with or without grinding and / or sieving:

[0065] Talc 1: Model SD-9449, manufacturer Liaoning Xinda, D95 particle size of talc 1 is 20 μm;

[0066] Talc 2: Model SD-9446, manufacturer Liaoning Xinda, D95 particle size of talc 2 is 15μm;

[0067] Talc 3: Model SD-9462, manufacturer Liaoning Xinda, D95 particle size of talcum powder 3 is 25μm.

[0068] The following performance tests were performed on the polylactic acid composite materials of the above examples and comparative examples:

[0069] Extrusion stability: The polylactic acid composite material was extruded on a single screw extruder, cut into tubes, and cooled in a water tank, wherein the extrusion temperature was 170°C, the extrusion speed was 50kg / h, the straw weight was 2.5g / piece, and the cooling temperature was 30°C. The extrusion stability of the polylactic acid composite material was characterized by the range and relative deviation of the straw weight. The range was defined as the difference between the maximum and minimum values, and the relative deviation was defined as the percentage of the absolute deviation of a certain measurement to the average value. The sample size for each test was 200 pieces.

[0070] The test results are shown in Table 3.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075] Table 3

[0076]

[0077]

[0078] It can be seen from the above data that the polylactic acid composite materials obtained in each embodiment of the present application have excellent extrusion stability. For example, the gram weight range of the prepared straws is <0.15g, and the relative deviation of the gram weight of the straws is <5%.

[0079] Comparative Examples 1 to 6 The T of the obtained polylactic acid composite material x -T g The dosage of PBAT in comparative example 7 is too low, resulting in a large extreme difference in gram weight and a large relative deviation in gram weight of the prepared straws.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application rather than to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A polylactic acid composite material, characterized in that, Comprising the following components in parts by weight: The polylactic acid composite material satisfies: 280°C ≤ T x - T g ≤ 310°C, Among them, T x is the initial decomposition temperature of the polylactic acid composite material, with the unit of °C, T g is the glass transition temperature of the polylactic acid composite material, in °C.

2. The polylactic acid composite material according to claim 1, characterized in that The T x is 330°C to 360°C.

3. The polylactic acid composite material according to claim 1, characterized in that, The said T g is 50°C to 60°C.

4. The polylactic acid composite material according to claim 1, wherein The terminal carboxyl content of the polybutylene terephthalate adipate is 10 - 20 mol KOH / t.

5. The polylactic acid composite material according to claim 1, wherein The terminal carboxyl content of the polybutylene succinate is 15 - 35 mol KOH / t.

6. The polylactic acid composite material according to claim 1, wherein The terminal carboxyl content of the polylactic acid is 10 - 30 mol KOH / t.

7. The polylactic acid composite material according to claim 1, characterized in that, The polylactic acid composite material satisfies at least one of the following conditions: S1. The polylactic acid comprises at least one of L-polylactic acid and D-polylactic acid; S2. The intrinsic viscosity of the polylactic acid is 0.9 - 1.5 dL / g; S3. The intrinsic viscosity of the polybutylene succinate is 1.4 - 1.8 dL / g; S4. The molar amount of adipic acid in the polybutylene terephthalate adipate is 70% - 100% of the molar amount of terephthalic acid; S5. The intrinsic viscosity of the polybutylene terephthalate adipate is 1.2 - 1.6 dL / g; S6. The particle size D95 of the talc powder satisfies 10 μm ≤ D95 ≤ 30 μm.

8. A method for preparing a polylactic acid composite material according to any one of claims 1 to 7, characterized in that, Comprising the following steps: mixing and dispersing all raw materials, melt-extruding, and pelletizing to obtain the polylactic acid composite material, wherein the melt-extrusion temperature is 160°C - 200°C.

9. The application of the polylactic acid composite material according to any one of claims 1 - 7 in food and beverage utensils.

10. A straw, characterized in that, The material of the straw comprises the polylactic acid composite material according to any one of claims 1 - 7.

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