Thermoplastic polyurethane elastomer toughened polylactic acid alloy material and preparation method thereof

Abstract

The invention discloses a thermoplastic polyurethane elastomer toughened polylactic acid alloy material and a preparation method thereof, and belongs to the technical field of high polymer materials, the alloy material comprises the following raw materials: thermoplastic polyurethane elastomer, polylactic acid, a cross-linking agent and carbodiimide; wherein the sum of the mass of the thermoplastic polyurethane elastomer and the mass of the polylactic acid is 100%, the mass ratio of the thermoplastic polyurethane elastomer is 10-40%, and the balance is the polylactic acid; the cross-linking agent accounts for 5-15% of the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid; the carbodiimide accounts for 0.5-2.5% of the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid, and the thermoplastic polyurethane elastomer / polylactic acid composite material with high toughness (high elongation and impact strength), high tensile strength, high mechanical strength and high mechanical strength is prepared by adopting a twin-screw segmented addition process technology according to the ratio of the raw materials. And meanwhile, the thermoplastic polyurethane elastomer toughened polylactic acid alloy material has high hydrolysis resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a thermoplastic polyurethane elastomer toughened polylactic acid alloy material and a preparation method thereof. Background Art

[0002] Polylactic acid (PLA) is a new type of bio-based biodegradable polymer material made from starch raw materials extracted from renewable plant resources such as corn and cassava. It can be completely degraded into CO under natural conditions. 2 and H 2 PLA has become an ideal green polymer material to replace petroleum-based plastics due to its excellent mechanical properties, strong processability, and biodegradability. However, its poor toughness (low elongation and impact strength) and easy hydrolysis have greatly hindered the widespread application of PLA, especially the hydrolysis and degradation during storage, transportation, and use, which causes PLA chain scission, reduces the mechanical properties of the products and shortens their service life, limiting its promotion and application.

[0003] Domestic and foreign researchers have carried out a large amount of research on the toughening and hydrolysis resistance of polylactic acid. Thermoplastic polyurethane elastomer (TPU) has the advantages of high strength, good elasticity, large elongation, hydrolysis resistance, wear resistance, good biocompatibility, etc., and is therefore applied to the research on the toughening of polylactic acid. Chinese patent CN106866947A prepares alloy materials by blending polyether polyurethane with PLA, which improves PLA toughness to a certain extent. Chinese patent CN107189386B prepares alloy materials by blending star polyurethane, diisocyanate and polylactic acid, and PLA toughness is improved. However, the tensile strength and hydrolysis resistance of the alloy materials prepared by the above-mentioned technology are relatively low.

[0004] In summary, there is an urgent need to provide a TPU / PLA alloy material that has high toughness (high elongation and impact strength), high tensile strength, and high hydrolysis resistance. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a thermoplastic polyurethane elastomer toughened polylactic acid alloy material and a preparation method thereof. The preparation method of the present invention can obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material that can significantly improve the toughness and hydrolysis resistance of polylactic acid without significantly reducing its tensile strength.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] A thermoplastic polyurethane elastomer toughened polylactic acid alloy material, comprising the following raw materials:

[0009] Thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide;

[0010] Wherein, taking the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid as 100%, the mass ratio of the thermoplastic polyurethane elastomer is 10-40%, and the remainder is polylactic acid;

[0011] The cross-linking agent is 5 to 15% of the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid;

[0012] The carbodiimide accounts for 0.5-2.5% of the total mass of the thermoplastic polyurethane elastomer and the polylactic acid.

[0013] Optionally, the thermoplastic polyurethane elastomer is composed of a hard segment and a soft segment, wherein the hard segment content is 10-60% and the balance is the soft segment; the R value is 1.03-1.05; the Shore hardness is 55A-70D, and the tensile strength is ≥40MPa;

[0014] Among them, the hard segment is composed of diisocyanate and small molecule diol chain extender;

[0015] The soft segment is composed of macromolecular polyols.

[0016] Further, the preparation process of thermoplastic polyurethane elastomer is:

[0017] The macromolecular polyol, diisocyanate and small molecular diol chain extender are placed in a twin-screw extruder and polymerized under the condition of an organic tin catalyst;

[0018] Furthermore, the macromolecular polyol is selected from at least one of polyester polyol (preferably polybutylene adipate, polyethylene adipate, polypropylene adipate, polyhexylene adipate, polybutylene succinate, polyethylene succinate, polybutylene sebacate, polycaprolactone polyol), polyether polyol (preferably polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol), polycarbonate polyol (preferably aliphatic polycarbonate polyol) or polysiloxane polyol; wherein the number average molecular weight of the macromolecular polyol is 1000 to 4000, preferably 2000 to 3500; and / or

[0019] The diisocyanate is at least one selected from aromatic diisocyanates (preferably toluene diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate) or aliphatic diisocyanates (preferably hexamethylene diisocyanate, isophorone diisocyanate); and / or

[0020] The small molecule diol chain extender is selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, diethylene glycol or dipropylene glycol, preferably at least one of ethylene glycol, 1,3-propylene glycol, butanediol or hexanediol; and / or

[0021] The organic tin catalyst is selected from at least one of stannous octoate or dibutyltin dilaurate, and the added amount is 0.001-0.002% of the mass of the thermoplastic polyurethane elastomer.

[0022] Furthermore, the temperature of the twin-screw extruder is set to 150° C. to 230° C., and the rotation speed is set to 60 to 180 r / min.

[0023] The second technical solution of the present invention:

[0024] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0025] According to the above dosage ratio, the dried thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide are melt-blended in a twin-screw extruder to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material.

[0026] Optionally, the preparation method specifically comprises the following steps:

[0027] According to the dosage ratio, the thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, the dried polylactic acid is added to the middle injection port of the extruder, and the cross-linking agent and carbodiimide are respectively added to the end feeding port of the extruder, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained after passing through an underwater pelletizing device and dehumidification.

[0028] Furthermore, the temperature setting of the twin-screw extruder is divided into two sections. The temperature of the section from the front injection port to the middle injection port is set to 180-230°C, which can be flexibly adjusted according to the melt index of the thermoplastic polyurethane elastomer. The temperature of the remaining section is set to 170-200°C, and the speed is set to 60-160r / min.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] 1. The present invention firstly adopts a twin-screw bulk polymerization process to prepare a thermoplastic polyurethane elastomer, and then melt-blends it with polylactic acid in a specific ratio through a twin-screw to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material. By limiting the composition of the polyurethane elastomer: the type of polyol and the number average molecular weight of 1000-4000, the hard segment content of 10-60%, and the R value of 1.03-1.05, a high-strength and high-toughness polyurethane elastomer (hardness 55A-70D, tensile strength ≥40MPa) is obtained, which can significantly improve the toughness (elongation, impact strength) and hydrolysis resistance of the alloy material without significantly reducing its tensile strength; on this basis, the introduction of a specific amount of cross-linking agent can further improve the tensile strength and hydrolysis resistance of the obtained alloy; the introduction of carbodiimide can further improve the hydrolysis resistance of the alloy material on the basis of ensuring the above-mentioned properties.

[0031] 2. The present invention adopts a twin-screw segmented addition process technology to prepare a thermoplastic polyurethane elastomer toughened polylactic acid alloy material, which is also applicable to the case where there is a large difference in the melt index of the two materials, and has the advantages of simple process, easy operation and high efficiency.

[0032] 3. The polylactic acid alloy material prepared by the present invention is suitable for processing technologies such as extrusion, injection molding, casting, film blowing, and spinning. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is the infrared spectrum of the polylactic acid alloy material prepared in Example 3. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The embodiment of the present invention discloses a thermoplastic polyurethane elastomer toughened polylactic acid alloy material, comprising the following raw materials:

[0041] Thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide;

[0042] Wherein, based on the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid being 100%, the mass ratio of the thermoplastic polyurethane elastomer is 10 to 40%, and the remainder is polylactic acid;

[0043] The cross-linking agent is 5 to 15% of the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid;

[0044] The carbodiimide accounts for 0.5-2.5% of the total mass of the thermoplastic polyurethane elastomer and the polylactic acid.

[0045] In some optional embodiments, the thermoplastic polyurethane elastomer is at least one of polyester type, polyether type, ester / ether mixed type, polycarbonate type or polysiloxane type; its hard segment content is 10-60%, R value is 1.03-1.05, Shore hardness is 55A-70D, and tensile strength is ≥40MPa, wherein the hard segment is composed of diisocyanate and small molecule diol chain extender.

[0046] In some optional embodiments, the thermoplastic polyurethane elastomer is prepared by polymerizing a macromolecular polyol, a diisocyanate and a small molecule diol chain extender under the condition of an organic tin catalyst;

[0047] The macromolecular polyol is selected from at least one of polyester polyols (polybutylene adipate, polyethylene adipate, polypropylene adipate, hexylene adipate, polybutylene succinate, polyethylene succinate, polybutylene sebacate, polycaprolactone polyol), polyether polyol (polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol), polycarbonate polyol (aliphatic polycarbonate polyol) or polysiloxane polyol; wherein the number average molecular weight of the macromolecular polyester polyol is 1000 to 4000, preferably 2000 to 3500;

[0048] The diisocyanate is selected from at least one of aromatic diisocyanates or aliphatic diisocyanates; further preferably selected from at least one of aromatic diisocyanates (toluene diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate or dimethylbiphenyl diisocyanate) and aliphatic diisocyanates (hexamethylene diisocyanate or isophorone diisocyanate);

[0049] The small molecule diol chain extender is selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, diethylene glycol or dipropylene glycol, and is further preferably selected from at least one of ethylene glycol, 1,3-propylene glycol, butanediol or hexanediol;

[0050] The organic tin catalyst is selected from at least one of stannous octoate or dibutyltin dilaurate, and the addition ratio is 0.001-0.002% of the mass of the thermoplastic polyurethane elastomer.

[0051] In some optional embodiments, the method for preparing a thermoplastic polyurethane elastomer specifically comprises the following steps:

[0052] The macromolecular polyol, diisocyanate and small molecule diol chain extender are heated and kept warm respectively;

[0053] The above raw materials are injected into the injection port of the twin-screw extruder according to the dosage ratio, and an organic tin catalyst is added at the same time. The raw materials react and polymerize under the shearing action of the twin-screw, and the thermoplastic polyurethane elastomer slices are obtained after passing through an underwater pelletizing device and dehumidification;

[0054] The temperature of the twin-screw extruder is set at 150°C to 230°C, and the rotation speed is set at 60 to 180 r / min.

[0055] In some optional embodiments, the polylactic acid is commercially available industrial grade polylactic acid.

[0056] In some optional embodiments, the crosslinking agent is a macromolecule with an NCO terminal synthesized from a macromolecular polyol and a diisocyanate, and the NCO content thereof is 5 to 15%, and the number average molecular weight is 6000 to 12000. The macromolecular polyol and the diisocyanate used for synthesizing the crosslinking agent are the same as those used for synthesizing the thermoplastic polyurethane elastomer. The crosslinking agent synthesis process of the present invention adopts the crosslinking agent synthesis process disclosed in the industry.

[0057] In some optional embodiments, the carbodiimide is selected from at least one of monocarbodiimide or polycarbodiimide, preferably polycarbodiimide.

[0058] The embodiment of the present invention also discloses a method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material, comprising the following steps:

[0059] According to the dosage ratio, the dried thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide are melt-blended in a twin-screw extruder to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material.

[0060] In some optional embodiments, the method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material specifically comprises the following steps:

[0061] According to the dosage ratio, the dried thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, the dried polylactic acid is added to the middle injection port of the extruder, and the cross-linking agent and carbodiimide are added to the end feeding port of the extruder respectively, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained after passing through an underwater pelletizing device and dehumidification;

[0062] Among them, the temperature setting of the twin-screw extruder is divided into two sections. The temperature of the section from the front injection port to the middle injection port is set at 180-230°C, which can be flexibly adjusted according to the melt index of the thermoplastic polyurethane elastomer. The temperature of the remaining section is set at 170-200°C, and the speed is set at 60-160r / min.

[0063] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0064] The raw materials used in the present invention are all purchased from the market.

[0065] The technical solution of the present invention is further illustrated by the following embodiments.

[0066] It should be noted that the matters not described in detail in the embodiments of the present invention, such as the synthesis process of the cross-linking agent, the pelletizing process using an underwater pelletizing device, the dehumidification process, etc., can all be carried out by conventional technical means, and are not the key points of the invention and will not be elaborated on.

[0067] Example 1

[0068] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0069] Step 1): Preparation of thermoplastic polyurethane elastomer

[0070] Polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol (BDO), and diphenylmethane diisocyanate (MDI) were heated and melted and kept warm respectively. The above materials were injected into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.0:3.67:4.91. At the same time, a stannous octoate catalyst was injected into the injection port, and the addition amount was 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder was set to 230°C, and the speed was set to 180r / min. The thermoplastic polyurethane elastomer slices were obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer had a hard segment content of 60% and an R value of 1.05.

[0071] Step 2): Preparation of polylactic acid alloy material

[0072] 40wt% of dried thermoplastic polyurethane elastomer is added to the front injection port of a twin-screw extruder, 60wt% of dried polylactic acid (Anhui Fengyuan, brand FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (using PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) and monocarbodiimide (bis(2,6-diisopropylbenzene)carbodiimide) (the content is 5% and 2.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then pelletized and dehumidified by an underwater pelletizing device to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material; wherein, the temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the rotation speed is set to 160r / min.

[0073] Example 2

[0074] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0075] Step 1): Preparation of thermoplastic polyurethane elastomer

[0076] Heat and melt polyadipate 1,6-hexanediol (PHA-4000) with a number average molecular weight of 4000, 1,4-butanediol, and hexamethylene diisocyanate (HDI) respectively. Inject the above materials into the injection port of the twin-screw extruder in proportion, the molar ratio of PHA-4000, BDO and HDI is 1:1.07:2.13, and at the same time inject dibutyltin dilaurate catalyst into the injection port, the addition amount is 0.002% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder is set to 150°C, the speed is set to 60r / min, and the thermoplastic polyurethane elastomer slices are obtained by underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer has a hard segment content of 10% and an R value of 1.03.

[0077] Step 2): Preparation of polylactic acid alloy material

[0078] 10wt% of the dried thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, 90wt% of the dried polylactic acid (Anhui Fengyuan, brand FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (PHA-4000 and HDI are used as raw materials, and the prepared cross-linking agent has a molecular weight of 6000 and an NCO content of 15%) and polycarbodiimide (BASF, brand: Bapu T01) (the content is 15% and 0.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained through an underwater pelletizing device and dehumidification. The temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 180°C, the temperature of the remaining section is set to 170°C, and the speed is set to 60r / min.

[0079] Example 3

[0080] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0081] Step 1): Preparation of thermoplastic polyurethane elastomer

[0082] Polytetrahydrofuran polyol (PTMEG-2000) with a number average molecular weight of 2000, ethylene glycol (EG), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI) are heated, melted, and kept warm. The above materials are injected into the injection port of a twin-screw extruder in proportion, and the molar ratio of PTMEG-2000, EG, MDI, and HDI is 1.00:2.39:1.76:1.76. At the same time, dibutyltin dilaurate catalyst is injected into the injection port, and the ratio is 0.0015% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder is set to 180°C, and the speed is set to 100r / min. The thermoplastic polyurethane elastomer slices are obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer has a hard segment content of 30% and an R value of 1.04.

[0083] Step 2): Preparation of polylactic acid alloy material

[0084] 20wt% of the dried thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, 80wt% of the dried polylactic acid (Anhui Fengyuan, brand FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (PTMEG-2000 and MDI are used as raw materials, and the prepared cross-linking agent has a molecular weight of 8000 and an NCO content of 10%) and polycarbodiimide (BASF, brand: Bapu T01) (the content is 10% and 1.0% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained through an underwater pelletizing device and dehumidification. The temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 200°C, the temperature of the remaining section is set to 180°C, and the speed is set to 100r / min.

[0085] Figure 1 This is the infrared spectrum of the polylactic acid alloy material prepared in Example 3. It can be seen that the characteristic absorption peaks of polylactic acid and TPU are clearly reflected, indicating that the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is successfully prepared.

[0086] Example 4

[0087] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0088] Step 1): Preparation of thermoplastic polyurethane elastomer

[0089] Polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol (BDO), and diphenylmethane diisocyanate (MDI) were heated and melted and kept warm respectively. The above materials were injected into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.0:3.67:4.91. At the same time, a stannous octoate catalyst was injected into the injection port, and the addition amount was 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder was set to 230°C, and the speed was set to 180r / min. The thermoplastic polyurethane elastomer slices were obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer had a hard segment content of 60% and an R value of 1.05.

[0090] Step 2): Preparation of polylactic acid alloy material

[0091] 40wt% of dried thermoplastic polyurethane elastomer is added to the front injection port of a twin-screw extruder, 60wt% of dried polylactic acid (Anhui Fengyuan, brand: FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (using PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) and polycarbodiimide (BASF, brand: Bapunai T01) (contents are 5% and 2.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then pelletized and dehumidified by an underwater pelletizing device to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material; wherein, the temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the rotation speed is set to 160r / min.

[0092] Comparative Example 1

[0093] A method for preparing a polylactic acid material comprises the following steps:

[0094] The dried polylactic acid (Anhui Fengyuan, brand: FY-601) was placed in a twin-screw extruder for melt extrusion (200°C), and then pelletized and dehumidified by an underwater pelletizing device to obtain the polylactic acid material. The screw speed was set at 160r / min.

[0095] Comparative Example 2

[0096] A method for preparing a polylactic acid alloy material comprises the following steps:

[0097] Step 1): Preparation of thermoplastic polyurethane elastomer

[0098] Heat and melt polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol (BDO), and diphenylmethane diisocyanate (MDI) respectively. Inject the above materials into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.0:3.67:4.77. At the same time, inject stannous octoate catalyst into the injection port, with a ratio of 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder is set at 230°C, and the speed is set at 180r / min. Thermoplastic polyurethane elastomer slices are obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer has a hard segment content of 60% and an R value of 1.02.

[0099] Step 2): Preparation of polylactic acid alloy material

[0100] 40wt% of the dried thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, and 60wt% of the dried polylactic acid (Anhui Fengyuan, brand: FY-601) is added to the middle injection port of the extruder, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained after passing through an underwater pelletizing device and dehumidification. The temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the speed is set to 160r / min.

[0101] Comparative Example 3

[0102] A method for preparing a polylactic acid alloy material comprises the following steps:

[0103] Step 1): Preparation of thermoplastic polyurethane elastomer

[0104] Polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol, and diphenylmethane diisocyanate (MDI) are heated and melted and kept warm respectively. The above materials are injected into the injection port of a twin-screw extruder in proportion, and the molar ratio of PBA-1000, BDO and MDI is 1.00:3.67:4.91. At the same time, a stannous octoate catalyst is injected into the injection port, and the ratio is 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder is set to 230°C, and the speed is set to 180r / min. The thermoplastic polyurethane elastomer slices are obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer has a hard segment content of 60% and an R value of 1.05.

[0105] Step 2): Preparation of polylactic acid alloy material

[0106] 40wt% of the dried thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, 60wt% of the dried polylactic acid (Anhui Fengyuan, brand: FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (with PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) is added to the end injection port of the extruder (the content is 5% of the total mass of the polyurethane elastomer and polylactic acid), and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained through an underwater pelletizing device and dehumidification. The temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the speed is set to 160r / min.

[0107] Comparative Example 4

[0108] A method for preparing a polylactic acid alloy material comprises the following steps:

[0109] Step 1): Preparation of thermoplastic polyurethane elastomer

[0110] Heat and melt poly(1,4-butylene adipate) polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butylene glycol, and diphenylmethane diisocyanate (MDI) respectively. Inject the above materials into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.00:3.67:4.77. At the same time, inject stannous octoate catalyst into the injection port, with a ratio of 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder is set at 230°C, and the speed is set at 180r / min. Thermoplastic polyurethane elastomer slices are obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer has a hard segment content of 60% and an R value of 1.02.

[0111] Step 2): Preparation of polylactic acid alloy material

[0112] 40wt% of dried thermoplastic polyurethane elastomer is added to the front injection port of a twin-screw extruder, 60wt% of dried polylactic acid (Anhui Fengyuan, brand FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (using PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) and monocarbodiimide (bis(2,6-diisopropylbenzene)carbodiimide) (the content is 5% and 2.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then pelletized and dehumidified by an underwater pelletizing device to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material; wherein, the temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the rotation speed is set to 160r / min.

[0113] Comparative Example 5

[0114] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0115] Step 1): Preparation of thermoplastic polyurethane elastomer

[0116] Polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol (BDO), and diphenylmethane diisocyanate (MDI) were heated and melted and kept warm respectively. The above materials were injected into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.0:3.67:4.91. At the same time, a stannous octoate catalyst was injected into the injection port, and the addition amount was 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder was set to 230°C, and the speed was set to 180r / min. The thermoplastic polyurethane elastomer slices were obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer had a hard segment content of 60% and an R value of 1.05.

[0117] Step 2): Preparation of polylactic acid alloy material

[0118] 5wt% of dried thermoplastic polyurethane elastomer is added to the front injection port of a twin-screw extruder, 95wt% of dried polylactic acid (Anhui Fengyuan, brand FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (using PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) and monocarbodiimide (bis(2,6-diisopropylbenzene)carbodiimide) (contents are 5% and 2.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then pelletized and dehumidified by an underwater pelletizing device to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material; wherein, the temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the rotation speed is set to 160r / min.

[0119] Comparative Example 6

[0120] The difference from Example 1 is that the amount of cross-linking agent is different

[0121] A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material comprises the following steps:

[0122] Step 1): Preparation of thermoplastic polyurethane elastomer

[0123] Polybutylene adipate polyol (PBA-1000) with a number average molecular weight of 1000, 1,4-butanediol (BDO), and diphenylmethane diisocyanate (MDI) were heated and melted and kept warm respectively. The above materials were injected into the injection port of a twin-screw extruder in proportion, with a molar ratio of PBA-1000, BDO, and MDI of 1.0:3.67:4.91. At the same time, a stannous octoate catalyst was injected into the injection port, and the addition amount was 0.001% of the mass of the thermoplastic polyurethane elastomer. The temperature of the twin-screw extruder was set to 230°C, and the speed was set to 180r / min. The thermoplastic polyurethane elastomer slices were obtained by an underwater pelletizer and dehumidification. The obtained thermoplastic polyurethane elastomer had a hard segment content of 60% and an R value of 1.05.

[0124] Step 2): Preparation of polylactic acid alloy material

[0125] 40wt% of dried thermoplastic polyurethane elastomer is added to the front injection port of a twin-screw extruder, 60wt% of dried polylactic acid (Anhui Fengyuan, brand: FY-601) is added to the middle injection port of the extruder, and a cross-linking agent (using PBA-1000 and MDI as raw materials, the prepared cross-linking agent has a molecular weight of 12000 and an NCO content of 5%) and monocarbodiimide (bis(2,6-diisopropylbenzene)carbodiimide) (the content is 3% and 2.5% of the total mass of the polyurethane elastomer and polylactic acid, respectively) are added to the end injection port of the extruder, and then pelletized and dehumidified by an underwater pelletizing device to obtain a thermoplastic polyurethane elastomer toughened polylactic acid alloy material; wherein, the temperature setting of the twin-screw extruder: the temperature of the section from the front injection port to the middle injection port is set to 230°C, the temperature of the remaining section is set to 200°C, and the rotation speed is set to 160r / min.

[0126] The polylactic acid alloy materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were subjected to mechanical property tests under the following test conditions:

[0127] Notched impact strength test: Tested according to ASTM D256, using an Izod impact tester;

[0128] Tensile strength and elongation at break test: Tested according to ASTM D412;

[0129] Tensile strength retention test: According to the standard ASTM D412, several dumbbell-shaped specimens were cut and hydrolyzed in distilled water at 38°C for 30 days. They were taken out and dried in a 100°C oven for 8 hours, and placed in a constant temperature and humidity environment at 23°C for 24 hours. The tensile strength A of the specimens before hydrolysis was tested. 1 , Tensile strength after hydrolysis A 2 , calculate the tensile strength retention rate:

[0130] Tensile strength retention rate = A2 / A 1 *100%.

[0131] The test results are shown in Table 1.

[0132] Table 1

[0133] serial number Tensile strength / MPa Elongation / % <![CDATA[Notched impact strength kJ / m 2 > Example 1 45.81 195 56.23 Example 2 49.52 75 26.28 Example 3 47.15 148 38.40 Example 4 47.97 164 48.61 Comparative Example 1 48.66 6.5 3.06 Comparative Example 2 30.47 61 16.89 Comparative Example 3 45.09 48 13.84 Comparative Example 4 35.27 56 20.30 Comparative Example 5 48.67 9.3 6.77 Comparative Example 6 35.24 43 19.58

[0134] The polylactic acid alloy materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were tested for hydrolysis resistance. The test results are shown in Table 2.

[0135] Table 2

[0136]

[0137]

[0138] It can be seen from Table 1 and Table 2 that, compared with Comparative Examples 1 to 6, the thermoplastic polyurethane elastomer toughened polylactic acid alloy prepared in Examples 1 to 4 has better toughness (elongation 75 to 195%, notched impact strength 26.28 to 56.23 kJ / m 2 ), while maintaining high tensile strength (≥45.8MPa) and hydrolysis resistance (tensile strength retention rate ≥85.1%).

[0139] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A thermoplastic polyurethane elastomer toughened polylactic acid alloy material, characterized in that: Including the following ingredients: Thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide; Wherein, taking the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid as 100%, the mass ratio of the thermoplastic polyurethane elastomer is 10-40%, and the remainder is polylactic acid; The cross-linking agent is 5 to 15% of the sum of the mass of the thermoplastic polyurethane elastomer and the polylactic acid; The carbodiimide accounts for 0.5-2.5% of the total mass of the thermoplastic polyurethane elastomer and the polylactic acid.

2. The thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 1, characterized in that: The thermoplastic polyurethane elastomer consists of a hard segment and a soft segment, wherein the content of the hard segment is 10-60% and the balance is the soft segment; the isocyanate index R value is 1.03-1.

05.

3. A thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 1 or 2, characterized in that: The preparation process of the thermoplastic polyurethane elastomer is: The macromolecular polyol, diisocyanate and small molecule diol chain extender are placed in a twin-screw extruder and polymerized under the condition of an organic tin catalyst.

4. The thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 3, characterized in that: The macromolecular polyol is selected from at least one of polyester polyol, polyether polyol, polycarbonate polyol or polysiloxane polyol, wherein the number average molecular weight of the macromolecular polyol is 1000 to 4000; and / or The diisocyanate is selected from at least one of aromatic diisocyanate and aliphatic diisocyanate; and / or The small molecule diol chain extender is selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, diethylene glycol or dipropylene glycol.

5. The thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 4, characterized in that: The macromolecular polyol is poly(1,4-butylene adipate) polyol with a number average molecular weight of 1000, the diisocyanate is diphenylmethane diisocyanate, and the small molecular diol chain extender is 1,4-butylene glycol.

6. The thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 3, characterized in that: The organic tin catalyst is stannous octoate or dibutyltin dilaurate, and the added amount thereof is 0.001-0.002% of the mass of the thermoplastic polyurethane elastomer.

7. The thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 3, characterized in that: The temperature of the twin-screw extruder is set at 150° C. to 230° C., and the rotation speed is set at 60 to 180 r / min.

8. A method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material, characterized in that: The following steps are involved: According to the dosage ratio, the thermoplastic polyurethane elastomer, polylactic acid, crosslinking agent and carbodiimide are melt-blended in a twin-screw extruder to obtain the thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to any one of claims 1 to 7.

9. The method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 8, characterized in that: The preparation method specifically comprises the following steps: According to the dosage ratio, the thermoplastic polyurethane elastomer is added to the front injection port of the twin-screw extruder, the dried polylactic acid is added to the middle injection port of the extruder, and the cross-linking agent and carbodiimide are respectively added to the end feeding port of the extruder, and then the thermoplastic polyurethane elastomer toughened polylactic acid alloy material is obtained after passing through an underwater pelletizing device and dehumidification.

10. The method for preparing a thermoplastic polyurethane elastomer toughened polylactic acid alloy material according to claim 9, characterized in that: The temperature setting of the twin-screw extruder is divided into two sections. The temperature of the section from the front injection port to the middle injection port is 180-230°C, the temperature of the remaining section is 170-200°C, and the rotation speed is 60-160r / min.

Images