Reinforced toughened polylactic acid composite material and preparation method and application thereof

Abstract

The application discloses a kind of reinforced toughening polylactic acid composite material and its preparation method and application, it is related to organic material field.Composite material includes polylactic acid, modified calcium carbonate, chain extender, lubricant;The preparation method of modified calcium carbonate is: calcium carbonate is mixed under high temperature condition to make moisture evaporate, fatty diacid is added and mixed, catalyst is added and mixed, poly-lactide dihydric alcohol is added and mixed, and modified calcium carbonate is obtained.This application adopts dry method chemical modification calcium carbonate, and the surface of calcium carbonate forms the coating layer with active lactic acid group, and the lactic acid group on the surface of modified calcium carbonate and polylactic acid are chemically bonded with chain extender to form a whole, which enhances the toughening effect of composite material, and the stability of modified calcium carbonate and polylactic acid is high, and the performance stability of material is good after long-term use.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic materials, in particular to a kind of reinforced toughening polylactic acid composite material and its preparation method and application. BACKGROUND

[0002] At present, PLA reinforcing toughening mainly has filling, plasticizing, blending and other physical modification and chemical grafting modification methods, filling modification mainly improves the strength of PLA material, when the filling agent is more, the toughness of PLA decreases, and the filler needs to be further modified and treated, and the steps are complicated. Plasticizing modification mainly improves the toughness of PLA material. Blending modification is a widely used modification method, and selecting appropriate toughening and reinforcing materials and PLA for binary blending can simultaneously improve the strength and toughness of PLA material, such as PLA / PA, PLA / PBAT, PLA / PCL and the like. Whether it is filling modification, plasticizing modification or blending modification, only a single modification component has higher strength, toughness and better compatibility with PLA, which can have reinforcing and toughening effect, and the physical modification method is simple and easy to operate, and is widely used, but the system performance is unstable for long-term use.

[0003] Chemical grafting modification is to combine components similar to system components or active groups with reactive groups on the main chain of PLA molecules through chemical bonds, which is a complex process and has high cost. Therefore, the grafting modification of PLA is generally not used as a substrate alone, but the grafting modified PLA is used as a small amount of modifier to improve some properties of PLA or to improve the compatibility of PLA with other additives.

[0004] At present, the modification treatment of fillers in materials can improve toughness and strength, including coating treatment by using coupling agent or coating by using chemical method, wherein the chemical coating is mainly carried out in solution, which is complicated to operate and not suitable for industrial production. The surface of the filler treated by coupling agent only increases the compatibility and dispersibility between the resin by intermolecular force, and does not produce chemical reaction with the resin, resulting in insufficient toughening and reinforcing range, and poor long-term performance stability. SUMMARY

[0005] The present application provides a kind of reinforced toughening polylactic acid composite material and its preparation method and application, to solve the technical problems of insufficient reinforcing toughening effect of current polylactic acid material and poor long-term performance stability of material.

[0006] In order to solve the above technical problems, one of the purposes of the present application provides a kind of reinforced toughening polylactic acid composite material, which comprises the following components by weight:

[0007] Polylactic acid: 55-85 parts;

[0008] Modified calcium carbonate: 20-40 parts;

[0009] chain extender: 0.2-0.4 parts;

[0010] lubricant: 0.2-0.4 parts;

[0011] The preparation method of the modified calcium carbonate is as follows: calcium carbonate is mixed under the condition of 150-170℃ to evaporate water, then fatty diacid is added and mixed, then catalyst is added and mixed, and finally poly-lactide dihydric alcohol is added and mixed, to obtain the modified calcium carbonate.

[0012] By using the above scheme, the calcium carbonate is chemically modified by dry method, and the calcium carbonate is chemically bonded with fatty diacid under high temperature condition. The fine antimony trioxide particles are filled in the gap between the calcium carbonate particles to improve the subsequent catalytic effect. The hydroxyl group of the poly-lactide dihydric alcohol can be esterified with the carboxyl group on the surface of the calcium carbonate to form a modified calcium carbonate coating layer with active lactic acid groups on the outside. Under the action of the chain extender, the lactic acid groups of the calcium carbonate coating layer and the poly-lactic acid are reacted with the epoxy groups of the chain extender to form a whole of the calcium carbonate and the poly-lactic acid resin through chemical reaction, effectively improving the toughness of the material. Moreover, the calcium carbonate is a rigid particle, and the existence of the rigid particle can improve the overall strength of the material. The calcium carbonate and the poly-lactic acid are linked through chemical reaction, and the linkage is firm, which can ensure the stable performance in long-term use.

[0013] As a preferred scheme, in the preparation method of the modified calcium carbonate, the calcium carbonate is heavy calcium carbonate, and the mesh number of the calcium carbonate is 2000-5000 mesh.

[0014] As a preferred scheme, in the preparation method of the modified calcium carbonate, the calcium carbonate is mixed under the condition of 150-160℃ to evaporate water to a content of less than 0.1wt%, then the fatty diacid is added and mixed for 3-5min, then the catalyst is added and mixed for 2-3min, and finally the poly-lactide dihydric alcohol is added and mixed for 5-10min, to obtain the modified calcium carbonate.

[0015] As a preferred scheme, in the preparation method of the modified calcium carbonate, at least one of the following a)-f) is satisfied:

[0016] a) the content of the fatty diacid is 1wt%-3wt% of the calcium carbonate;

[0017] b) the content of the catalyst is 0.5wt%-2wt% of the calcium carbonate;

[0018] c) the content of the poly-lactide dihydric alcohol is 1wt%-3wt% of the calcium carbonate;

[0019] d) the molecular weight of the poly-lactide dihydric alcohol is 1000-2000;

[0020] e) the catalyst is at least one of antimony trioxide, calcium chloride, lithium chloride, tetrabutyl titanate;

[0021] f) the fatty diacid is at least one of tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0022] As a preferred solution, the catalyst is antimony trioxide, with a content of > 99.5%, and a mesh number of 8000-12000.

[0023] As a preferred solution, at least one of a)-c) is satisfied:

[0024] a) the melt index of the polylactic acid is 5-10 g / 10 min;

[0025] b) the chain extender is a multi-epoxy compound;

[0026] c) the lubricant is at least one of polyester wax, OPE wax, EVA wax, calcium stearate, PETS.

[0027] As a preferred solution, the chain extender is at least one of glycidyl methacrylate, glycidyl acrylate, (3,4-epoxycyclohexyl) methyl methacrylate chain extender.

[0028] As a preferred solution, the chain extender is a styrene and glycidyl acrylate copolymer.

[0029] To solve the above technical problems, the second object of the present application provides a preparation method of a reinforced and toughened polylactic acid composite material, comprising the following steps: cooling modified calcium carbonate and uniformly mixing it with polylactic acid, a chain extender and a lubricant, and then feeding it into a double screw extrusion device for extrusion granulation to obtain.

[0030] As a preferred solution, the cooling temperature of the modified calcium carbonate is 50-60℃, the length-diameter ratio of the screw of the double screw extrusion device is 44:1, and the extrusion temperature is 160-190℃.

[0031] To solve the above technical problems, the third object of the present application provides an application of a reinforced and toughened polylactic acid composite material in the field of disposable products, which can be cosmetic bottles, knives, forks and spoons, etc.

[0032] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0033] 1. This application uses a dry chemical coating method to modify calcium carbonate, forming a coating layer with active lactic acid groups on the surface of the calcium carbonate. Under the action of the chain extender, the lactic acid groups and polylactic acid on the surface of the modified calcium carbonate are chemically bonded to the chain extender to form an integral whole, which enhances and toughens the composite material. Since the modified calcium carbonate and polylactic acid are chemically bonded, the stability is high and the material has good performance stability after long-term use.

[0034] 2. The dry chemical coating process for modified calcium carbonate in this application is simple. It utilizes the chemical bonding between calcium carbonate and fatty acid diacid. During the mixing process, fine antimony trioxide particles fill the gaps between calcium carbonate particles to improve the subsequent catalytic effect. The hydroxyl groups of polylactide diol can undergo esterification with the carboxyl groups on the surface of calcium carbonate. The final modified calcium carbonate coating layer has active lactic acid groups on the outside, which is suitable for industrial production.

[0035] 3. The polylactic acid composite material of this application has a high amount of modified calcium carbonate, and the raw material price of calcium carbonate is cheap, resulting in low production cost and high cost performance, which broadens the application field of the composite material. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the reaction between calcium carbonate and octadecanoic acid in step S1 of the present invention.

[0037] Figure 2 : This refers to step S1 of the preparation process in this embodiment of the invention. Figure 1 A schematic diagram of the reaction between calcium carbonate and polylactide diol after the reaction;

[0038] Figure 3 : This is a schematic diagram of the reaction of modified calcium carbonate, chain extender A and polylactic acid in preparation step S2 of this embodiment of the invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Table 1 below shows the sources of raw materials used in the embodiments and comparative examples of this application. Unless otherwise specified, polyester wax, OPE wax, and EVA wax were obtained commercially available, and the same polyester wax, OPE wax, and EVA wax were used in the parallel experiments.

[0041] Table 1 - Sources of raw materials for the embodiments and comparative examples of this application

[0042]

[0043]

[0044] Example 1

[0045] A reinforced and toughened polylactic acid composite material, comprising 79.4 kg of polylactic acid (PLA), 20 kg of modified calcium carbonate, 0.2 kg of chain extender A, and 0.4 kg of lubricant, wherein the melt index of the polylactic acid is 5-10 g / 10 min, the chain extender A is ADR4468, and the lubricant is polyester wax.

[0046] Example 2

[0047] A reinforced and toughened polylactic acid composite material, comprising 69.4 kg of polylactic acid (PLA), 30 kg of modified calcium carbonate, 0.3 kg of chain extender A, and 0.3 kg of lubricant, wherein the melt index of the polylactic acid is 5-10 g / 10 min, the chain extender A is ADR4468, and the lubricant is OPE wax.

[0048] Example 3

[0049] A reinforced and toughened polylactic acid composite material, comprising 59.4 kg of polylactic acid (PLA), 40 kg of modified calcium carbonate, 0.4 kg of chain extender A, and 0.2 kg of lubricant, wherein the melt index of the polylactic acid is 5-10 g / 10 min, the chain extender A is ADR4468, and the lubricant is EVA wax.

[0050] A method for preparing the reinforced and toughened polylactic acid composite material of any one of the above Examples 1-3, comprising the following steps:

[0051] S1: Put heavy calcium carbonate with a mesh size of 3000 into a high-speed mixer at 150°C, mix for 10 min to make the moisture content of the heavy calcium carbonate below 0.1%, then add 1.5 wt% of fatty diacid based on the mass of the heavy calcium carbonate, mix for 5 min, then add 1 wt% of antimony trioxide catalyst based on the mass of the heavy calcium carbonate, mix for 3 min, and finally add 2 wt% of polylactide diol based on the mass of the heavy calcium carbonate, mix for 10 min to obtain modified calcium carbonate;

[0052] S2: After cooling the modified calcium carbonate to 50°C, mix it uniformly with polylactic acid, chain extender A, and lubricant, and then put it into a twin-screw extruder for extrusion and granulation to obtain, wherein the length-diameter ratio of the screw is 44:1, and the extrusion temperature is 160-190°C.

[0053] Example 4

[0054] A reinforced and toughened polylactic acid composite material, wherein the steps and reagents and process parameters used in each step are the same as those of Example 2, except that chain extender B is used instead of chain extender A.

[0055] Example 5

[0056] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that the mixing temperature in S1 is 170℃.

[0057] Example 6

[0058] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that the mesh of heavy calcium carbonate in S1 is 2000 mesh.

[0059] Example 7

[0060] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that the mesh of heavy calcium carbonate in S1 is 5000 mesh.

[0061] Comparative Example 1

[0062] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that the addition amount of chain extender A is 0.

[0063] Comparative Example 2

[0064] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that in S2, the modified calcium carbonate is replaced by an equal amount of heavy calcium carbonate.

[0065] Comparative Example 3

[0066] A reinforced and toughened polylactic acid composite material, each step and the reagents, process parameters used in each step are the same as example 2, the difference is that in S2, the modified calcium carbonate is replaced by an equal amount of coupling agent treated calcium carbonate, and the preparation method of the coupling agent treated calcium carbonate is as follows: put the heavy calcium carbonate into a high-speed mixer at 150℃, mix for 10min to make the moisture content of the heavy calcium carbonate below 0.1%, then add 1% of the mass of the heavy calcium carbonate of aluminate coupling agent and mix for 5min.

[0067] Comparative Example 4

[0068] A reinforced and toughened polylactic acid composite material, each step and reagent, process parameters used in each step are the same as example 2, the difference is that in S1, the heavy calcium carbonate with mesh number of 3000 is put into a high-speed mixer at 150℃, and mixed for 10 min to make the moisture content of the heavy calcium carbonate below 0.1%, then 1wt% of the heavy calcium carbonate of antimony trioxide catalyst is added and mixed for 3 min, finally 2wt% of the heavy calcium carbonate of polylactide dihydric alcohol is added and mixed for 10 min, to obtain the modified calcium carbonate.

[0069] Comparative example 5

[0070] A reinforced and toughened polylactic acid composite material, each step and reagent, process parameters used in each step are the same as example 2, the difference is that in S2, the addition amount of the modified calcium carbonate is 0.

[0071] Comparative example 6

[0072] A reinforced and toughened polylactic acid composite material, each step and reagent, process parameters used in each step are the same as example 2, the difference is that in S1, the mixing temperature is 140℃.

[0073] Performance detection experiment

[0074] 1. The tensile strength and fracture nominal strain of the composite material of the examples and comparative examples were detected according to GB / T1042.2 standard, 50mm / min, and the detection results are shown in Table 2 below.

[0075] 2. The bending strength and bending modulus of the composite material of the examples and comparative examples were detected according to GB / T 9341 standard, 2mm / min, and the detection results are shown in Table 2 below.

[0076] 3. The Izod notched impact strength of the composite material of the examples and comparative examples was detected according to GB / T 1843 standard, V notch, 2.75J, and the detection results are shown in Table 2 below.

[0077] 4. Stability: The Izod notched impact strength of the sample was tested after being placed in an oven at 50℃ for 720h according to the principle of accelerated thermal oxidation, and the detection results are shown in Table 2 below.

[0078] Table 2-Performance detection results of the examples and comparative examples of the application

[0079]

[0080]

[0081] Based on the performance test results of Examples 1-3 in Table 2, it can be seen that as the amount of modified calcium carbonate added increases, the rigidity and toughness of the material increase accordingly. The material reaches its optimal state when the amount of added calcium carbonate reaches 30%, and then the rigidity decreases with the increase of the amount of added calcium carbonate.

[0082] Based on the performance test results of Example 2 and Comparative Example 1 in Table 2, it can be seen that this application utilizes chain extender A to react with the lactic acid groups on the surface coating of modified calcium carbonate to form epoxy groups. At the same time, polylactic acid also reacts with chain extender A to form epoxy groups. Through chemical reaction, modified calcium carbonate and polylactic acid are linked into a linear bond. Since the link is a chemical reaction, the bond is strong, ensuring the long-term stable performance of the material. The toughness and rigidity of the material are significantly improved.

[0083] Combination Figures 1-3 As shown in Table 2, the performance test results of Examples 2 and Comparative Examples 2-5 indicate that the calcium carbonate in Comparative Example 2 was not surface-treated, resulting in poor compatibility with polylactic acid in the system, and insufficient toughness and rigidity of the material. In Comparative Example 3, the calcium carbonate was surface-treated with a coupling agent. Although the compatibility between calcium carbonate and polylactic acid improved, the increase in toughness and rigidity was still small due to intermolecular forces alone, and long-term performance stability was insufficient. In Comparative Example 4, after directly treating calcium carbonate with polylactide diol, the final composite material had lower toughness and rigidity than the material in this application. This is presumably because the molecular weight of polylactide diol is too large, making it difficult to chemically bond with the surface hydroxyl groups of calcium carbonate. In contrast, the material in this application… By chemically bonding calcium carbonate and octadecanoic acid under high temperature conditions, fine antimony trioxide particles fill the gaps between calcium carbonate particles during high-speed mixing, thereby improving the subsequent catalytic effect. The hydroxyl groups of polylactide diol undergo esterification with the carboxyl groups on the surface of calcium carbonate. The water produced during the reaction is vaporized into water vapor and discharged under high temperature conditions, ensuring the forward esterification reaction and improving the esterification rate. The modified calcium carbonate coating layer has lactic acid groups on the outside, which helps the modified calcium carbonate to be compatible and dispersed in the polylactic acid system. At the same time, the chain extender is used to achieve chemical bonding with polylactic acid, which greatly improves the rigidity and toughness of the composite material and the long-term performance stability of the material is good.

[0084] Based on the performance test results of Examples 2 and 5 and Comparative Example 6 in Table 2, it can be seen that when the temperature is too low, the surface treatment effect is not ideal, and the treatment effect cannot be achieved when the temperature is too low. It is speculated that this may be due to insufficient reaction energy and low material reactivity. Conversely, when the temperature is too high, although the reaction energy is sufficient, some side reactions will be generated, which will affect the performance.

[0085] From the performance test results of Examples 2 and 7-8 in Table 2, it can be seen that the greater the mesh number of calcium carbonate, the better the rigidity and toughness of the material, and vice versa. This is mainly because the greater the mesh number, the finer the calcium carbonate, and the smaller the particle size. The small particles distributed in the resin exhibit small size effect, and the interface area with the resin increases, thereby greatly improving the comprehensive performance of the composite material.

[0086] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are merely examples of the present application and are not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A reinforced toughened polylactic acid composite material, characterized by, The following weight parts of components are included: Polylactic acid: 55-85 parts; Modified calcium carbonate: 20-40 parts; Chain extender: 0.2-0.4 parts; Lubricant: 0.2-0.4 parts; The preparation method of the modified calcium carbonate is as follows: the calcium carbonate is mixed while kept at 150-170℃ to evaporate the moisture, then fatty diacid is added and mixed, followed by the addition of a catalyst and mixing, and finally the addition of polylactide glycol and mixing to obtain the modified calcium carbonate; In the preparation method of the modified calcium carbonate, the calcium carbonate is heavy calcium carbonate, and the mesh number of the calcium carbonate is 2000-5000 mesh; The preparation method of the modified calcium carbonate satisfies the following a)-d): a) the content of the fatty diacid is 1wt%-3wt% of the calcium carbonate; b) the content of the catalyst is 0.5wt%-2wt% of the calcium carbonate; c) the content of the polylactide glycol is 1wt%-3wt% of the calcium carbonate; d) the molecular weight of the polylactide glycol is 1000-2000.

2. The reinforced and toughened polylactic acid composite material according to claim 1, characterized in that, In the preparation method of the modified calcium carbonate, the calcium carbonate is mixed while kept at 150-160℃ to evaporate the moisture to a content of less than 0.1wt%, then fatty diacid is added and mixed for 3-5min, followed by the addition of a catalyst and mixing for 2-3min, and finally the addition of polylactide glycol and mixing for 5-10min to obtain the modified calcium carbonate.

3. The reinforced and toughened polylactic acid composite material according to claim 1, characterized in that, The preparation method of the modified calcium carbonate satisfies at least one of the following a)-b): a) the catalyst is at least one of antimony trioxide, calcium chloride, lithium chloride, and tetrabutyl titanate; b) the fatty diacid is at least one of tetradecanedioic acid, hexadecanedioic acid, and octadecanedioic acid.

4. The reinforced and toughened polylactic acid composite material according to claim 3, characterized in that, The catalyst is antimony trioxide with a content of ≥99.5% and a mesh number of 8000-12000 mesh.

5. The reinforced and toughened polylactic acid composite material according to claim 1, wherein the reinforcing and toughening polylactic acid composite material is a polylactic acid composite material comprising the polylactic acid, the reinforcing material, and the toughening material. At least one of the following a)-c) is satisfied: a) the melt index of the polylactic acid is 5-10g / 10min; b) the chain extender is a multi-epoxy compound; c) the lubricant is at least one of polyester wax, OPE wax, EVA wax, calcium stearate, and PETS.

6. The reinforced and toughened polylactic acid composite material according to claim 5, characterized in that, The chain extender is at least one of glycidyl methacrylate, glycidyl acrylate, and (3,4-epoxycyclohexyl) methyl methacrylate chain extender.

7. A method of producing a reinforced and toughened polylactic acid composite material as claimed in any one of claims 1 to 6, characterized in that, The following steps are included: After the modified calcium carbonate is cooled, it is mixed uniformly with the polylactic acid, chain extender, and lubricant, and then fed into a double-screw extrusion device for extrusion granulation to obtain the product.

8. The method for preparing a reinforced and toughened polylactic acid composite material as described in claim 7, characterized in that, The cooling temperature of the modified calcium carbonate is 50-60℃, the length-diameter ratio of the screw of the double-screw extrusion device is 44:1, and the extrusion temperature is 160-190℃.

9. Use of the reinforced and toughened polylactic acid composite material of any one of claims 1-6 in the field of disposable products.

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