Polylactic acid elastomer containing cardanol acetate as well as preparation method and application of polylactic acid elastomer

Abstract

The invention belongs to the technical field of thermoplastic elastomer preparation, and relates to a polylactic acid elastomer containing cardanol acetate and a preparation method and application thereof. The polylactic acid elastomer is prepared from the following raw materials in parts by weight: 20 to 40 parts of polylactic acid, 5 to 20 parts of polycaprolactone, 0.01 to 0.05 part of cardanol acetate and 0.01 to 0.45 part of an epoxy silane coupling agent. The cardanol acetate and the epoxy silane coupling agent are introduced into a polylactic acid (PLA) and polycaprolactone (PCL) blending system, so that the compatibility of the blending system can be effectively improved, the tensile strength and the elongation at break are further improved while the toughness of the elastomer is improved, and meanwhile, the cardanol acetate modified polylactic acid elastomer has very good biodegradability and a wider application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoplastic elastomer preparation, and relates to a polylactic acid elastomer containing cardanol acetate, and a preparation method and application thereof. Background Art

[0002] Polylactic acid (PLA) is a thermoplastic linear aliphatic polyester with excellent biodegradability, biocompatibility, good mechanical properties, optical properties, air permeability and easy processing. It can replace traditional petroleum-based raw materials and is even comparable to general-purpose plastics such as polypropylene and polystyrene. However, it also has some shortcomings, such as slow crystallization, high brittleness, poor impact resistance, etc., so it needs to be toughened and modified.

[0003] The physical blending method for toughening modification of PLA is simple and convenient, and is the most commonly used modification method in industrial production. It is to blend PLA with materials such as elastomers, inorganic fillers or plasticizers to improve the toughness of PLA. However, most flexible polymers are incompatible or partially compatible with PLA during the blending process, resulting in a larger dispersion size, obvious phase separation between the dispersed phase and the matrix phase, and poor adhesion between the two phases, which ultimately leads to a decrease in the overall strength of the material and the toughening effect cannot be fully exerted. Therefore, it is often necessary to add a compatibilizer, a nucleating agent or inorganic nanoparticles to improve the interfacial compatibility between the two and improve the performance of the material.

[0004] For example, Chinese invention patent application CN116904007A discloses a biodegradable toughened high-temperature resistant straw material and its preparation method, which includes the following components: polylactic acid, toughening resin, PCLLA-PU polymer, filler, compatibilizer, nucleating agent, antioxidant, coupling agent and erucamide. While it uses resins such as polybutylene succinate, polycaprolactone, polyhydroxyalkanoate and polymethyl ethylene carbonate to toughen the polylactic acid, it also needs to add compatibilizers, nucleating agents, coupling agents, etc. to improve the compatibility of the blending system, and add fillers to improve the strength. The composition is relatively complex, which greatly increases the difficulty of preparation.

[0005] Compared with traditional toughening agents, bio-based toughening agents use biomass such as soybean oil, cardanol, castor oil, waste cooking oil, lactic acid and other raw materials that contain many convertible functional groups such as double bonds, hydroxyl groups, ester groups, carboxyl groups, ether groups, carbonyl groups and epoxy groups. While ensuring environmental protection and low toxicity, good mechanical and thermal stability are obtained through modification.

[0006] Chinese invention patent application CN118388942A discloses a method for preparing a PLA-based biodegradable composite material, in which a bio-based compatibilizer cardanol (CD) is melt-blended and extruded with PLA, PCL and an antioxidant. The impact properties, elongation at break, processing properties and expected optical properties of the composite material are improved, but its strength still decreases to varying degrees.

[0007] Cardanol has attracted more and more attention in the toughening modifier industry due to its unique chemical structure. Cardanol has both the reactivity of phenolic compounds and the flexibility of aliphatic compounds. Its unique chemical structure determines that it can react with many organic or inorganic compounds for structural modification. In recent years, many studies have focused on using cardanol and acetic anhydride as raw materials and performing corresponding modifications to obtain cardanol acetate (CA), including epoxy cardanol acetate, acetylated cardanol acetate, etc. Its application in toughening modification of polylactic acid still needs to be further studied. Summary of the invention

[0008] The present invention aims at the problems existing in the prior art, and provides a polylactic acid elastomer containing cardanol acetate, and a preparation method and application thereof. Introducing cardanol acetate and epoxy silane coupling agent into a polylactic acid (PLA) and polycaprolactone (PCL) blending system can effectively improve the compatibility of the blending system, while improving the toughness of the elastomer, further improving the tensile strength and elongation at break, and having good biodegradability, and having a wider application prospect.

[0009] The technical solution of the present invention is as follows:

[0010] The invention provides a polylactic acid elastomer containing cardanol acetate. The polylactic acid elastomer is prepared from the following raw materials in parts by weight: 20-40 parts of polylactic acid, 5-20 parts of polycaprolactone, 0.01-0.05 parts of cardanol acetate and 0.01-0.45 parts of epoxy silane coupling agent.

[0011] Preferably, the polylactic acid elastomer is prepared from the following raw materials in parts by weight: 30-40 parts of polylactic acid, 5-10 parts of polycaprolactone, 0.02-0.05 parts of cardanol acetate and 0.05-0.2 parts of epoxy silane coupling agent.

[0012] Further preferably, the polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of epoxy silane coupling agent.

[0013] In some embodiments of the present invention, the cardanol acetate is epoxidized dicardanol carbonate, and the structure is as follows:

[0014]

[0015] Wherein, R1 and R2 are each independently selected from

[0016]

[0017] In the present invention, epoxidized cardanol carbonate is a derivative of cardanol, which has a double-branched multi-epoxy functional group. When used as a toughening agent, it can toughen the matrix polymer and significantly improve its tensile strength and elongation at break.

[0018] Furthermore, the epoxy value of the epoxidized cardanol carbonate is 4-7%.

[0019] In some preferred embodiments of the present invention, the total mass of the cardanol acetate and the epoxy silane coupling agent accounts for 0.05-0.2% of the total mass of the polylactic acid and the polycaprolactone.

[0020] In some preferred embodiments of the present invention, the mass ratio of the cardanol acetate to the epoxy silane coupling agent is 1:1-5.

[0021] The present invention also provides a method for preparing the polylactic acid elastomer, comprising the following steps:

[0022] (1) Polylactic acid modification: adding epoxy silane coupling agent to polylactic acid, heating and modifying the polylactic acid to obtain modified polylactic acid;

[0023] (2) Blending: Put polycaprolactone, epoxidized cardanol carbonate and modified polylactic acid into a twin-screw extruder for melt blending, and granulate them by extrusion to obtain the product.

[0024] Furthermore, in step (1), the heating temperature is 80-100° C. and the time is 20-40 min.

[0025] Furthermore, in step (2), the temperature of the feeding zone of the twin-screw extruder is 90-120°C, the temperature of the reaction zone is 140-180°C, the temperature of the extrusion zone is 240-160°C; and the extrusion speed is 80150r / min.

[0026] The present invention also provides the use of the polylactic acid elastomer or the polylactic acid elastomer prepared by the above preparation method in drug transportation materials, agricultural mulch materials or food packaging materials.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention uses flexible polymer polycaprolactone PCL to blend and modify polylactic acid PLA. Under the joint action of cardanol acetate and epoxy silane coupling agent, the compatibility of the blending system can be significantly improved, and the mechanical toughness of the obtained elastomer is significantly improved; at the same time, without the need to use reinforcing fillers, its tensile strength and elongation at break are also improved to a certain extent; on the other hand, the presence of cardanol acetate also significantly improves the degradation performance of the material;

[0029] (2) In addition, the present invention maximizes the toughening and strengthening effect of the elastomer by regulating the amount of each component; and the degradation performance of the polylactic acid elastomer is also improved to a certain extent by controlling the amount ratio of polylactic acid and polycaprolactone;

[0030] (3) In the preparation process of the elastomer of the present invention, polylactic acid is first modified with an epoxy silane coupling agent, and then blended with polycaprolactone and cardanol acetate. Compared with the elastomer obtained by direct one-step blending, the elastomer can maintain the same toughness while further improving the strength, and the comprehensive effect is further improved;

[0031] (4) The amount of toughening agent and coupling agent used in the blending of the present invention is low, which reduces the preparation cost; and the physical blending is simple and easy to realize industrial production. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited.

[0033] The raw material information used in the comparative examples of the present invention is as follows:

[0034] Polylactic acid is racemic polylactic acid with a weight average molecular weight of 30,000-60,000;

[0035] The weight average molecular weight of polycaprolactone is 40,000-50,000;

[0036] Epoxidized dicardanol carbonate was prepared according to the method of Example 3 of Patent ZL202110040624.6, with an epoxy value of 4.3%;

[0037] (2,3-Epoxypropyl)propyltrimethoxysilane, model number Crosile-560, was purchased from Yongxiu County Aikopu New Materials Co., Ltd.

[0038] Example 1

[0039] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0040] The preparation method is as follows:

[0041] 3-(2,3-epoxypropoxy)propyltrimethoxysilane and polylactic acid were added to tetrahydrofuran according to the above-mentioned amounts, and the temperature was raised to 100°C for reaction for 30 minutes to obtain modified polylactic acid; then the above-mentioned amounts of polycaprolactone, epoxidized dicardanol carbonate and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0042] Example 2

[0043] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 30 parts of polylactic acid, 5 parts of polycaprolactone, 0.01 parts of cardanol acetate and 0.05 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0044] 3-(2,3-epoxypropoxy)propyltrimethoxysilane and polylactic acid were added to tetrahydrofuran according to the above-mentioned amounts, and the temperature was raised to 100°C for reaction for 30 minutes to obtain modified polylactic acid; then the above-mentioned amounts of polycaprolactone, epoxidized dicardanol carbonate and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0045] Example 3

[0046] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 20 parts of polylactic acid, 20 parts of polycaprolactone, 0.02 parts of cardanol acetate and 0.03 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0047] 3-(2,3-epoxypropoxy)propyltrimethoxysilane and polylactic acid were added to tetrahydrofuran according to the above-mentioned amounts, and the temperature was raised to 100°C for reaction for 30 minutes to obtain modified polylactic acid; then the above-mentioned amounts of polycaprolactone, epoxidized dicardanol carbonate and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0048] Example 4

[0049] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.2 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0050] 3-(2,3-epoxypropoxy)propyltrimethoxysilane and polylactic acid were added to tetrahydrofuran according to the above-mentioned amounts, and the temperature was raised to 100°C for reaction for 30 minutes to obtain modified polylactic acid; then the above-mentioned amounts of polycaprolactone, epoxidized dicardanol carbonate and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0051] Example 5

[0052] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.02 parts of cardanol acetate and 0.2 parts of gamma-glycidyloxypropyltrimethoxysilane (KH560 silane coupling agent).

[0053] KH560 silane coupling agent and polylactic acid were added to tetrahydrofuran according to the above amounts, and the temperature was raised to 80°C for reaction for 40 minutes to obtain modified polylactic acid; then the above amounts of polycaprolactone, epoxidized dicardanol carbonate and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 180°C, and the extrusion zone temperature was set to 240°C; the extrusion speed was 150r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0054] Comparative Example 1

[0055] A polylactic acid elastomer, which is different from Example 1 only in that it is prepared from the following raw materials in parts by weight: 45 parts of polylactic acid, 5 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0056] The preparation method is the same as Example 1.

[0057] Comparative Example 2

[0058] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone and 0.1 parts of cardanol acetate.

[0059] The preparation method is as follows:

[0060] Polycaprolactone, epoxidized cardanol carbonate and polylactic acid were fed into a twin-screw extruder for melt blending according to the above amounts. The feeding zone temperature was set at 120°C, the reaction zone temperature was set at 150°C, and the extrusion zone temperature was set at 200°C. The extrusion speed was set at 100 r / min. After extrusion, granulation was performed to obtain a polylactic acid elastomer.

[0061] Comparative Example 3

[0062] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone and 0.1 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0063] 3-(2,3-epoxypropoxy)propyltrimethoxysilane and polylactic acid were added to tetrahydrofuran according to the above-mentioned amounts, and the temperature was raised to 100°C for reaction for 30 minutes to obtain modified polylactic acid; then the above-mentioned amounts of polycaprolactone and modified polylactic acid were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0064] Comparative Example 4

[0065] A polylactic acid elastomer, which differs from Example 1 only in that it is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of γ-methacryloxypropyltrimethoxysilane (KH570 silane coupling agent).

[0066] KH570 silane coupling agent and polylactic acid are added to tetrahydrofuran according to the above amount, the temperature is raised to 100°C and reacted for 30 minutes to obtain modified polylactic acid; then the above amount of polycaprolactone, epoxidized dicardanol carbonate and the above modified polylactic acid are put into a twin-screw extruder for melt blending, and the feeding zone temperature is set to 120°C, the reaction zone temperature is set to 150°C, and the extrusion zone temperature is set to 200°C; the extrusion speed is 100r / min, and granulation is performed after extrusion to obtain a polylactic acid elastomer.

[0067] Comparative Example 5

[0068] A polylactic acid elastomer is prepared from the following raw materials in parts by weight: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0069] Polylactic acid, polycaprolactone, cardanol acetate and 3-(2,3-epoxypropoxy)propyltrimethoxysilane in the above amounts were put into a twin-screw extruder for melt blending, and the feeding zone temperature was set to 120°C, the reaction zone temperature was set to 150°C, and the extrusion zone temperature was set to 200°C; the extrusion speed was 100r / min, and granulation was performed after extrusion to obtain a polylactic acid elastomer.

[0070] Test Example 1: Mechanical Properties Test

[0071] The polylactic acid elastomer particles prepared in the comparative examples of the above embodiments were injection molded using an injection molding machine, and the samples were injection molded into tensile test strips according to the national standard GB / T 1040.2-2006; and injection molded into impact test strips according to the national standard GB / T 1843-2008, and their mechanical properties were tested. The test conditions are as follows:

[0072] The impact strength was tested according to GB / T 1043.1-2008; the tensile strength and elongation at break were tested according to GB / T1040.2-2006. The results are shown in Table 1.

[0073] Table 1 Mechanical properties test results

[0074] <![CDATA[Impact strength (kJ / m 2 )]]> Tensile strength(MPa) Elongation at break (%) Example 1 45.33 42.10 548.21 Example 2 41.57 40.98 535.66 Example 3 42.85 40.45 530.12 Example 4 37.20 38.33 525.60 Example 5 35.42 36.42 520.78 Comparative Example 1 25.47 35.42 433.67 Comparative Example 2 32.17 29.81 406.50 Comparative Example 3 24.95 33.12 467.85 Comparative Example 4 30.28 24.55 387.16 Comparative Example 5 35.42 28.99 438.47

[0075] As can be seen from the above table: the present invention uses epoxy silane coupling agent to modify polylactic acid, and then in the presence of cardanol acetate, it is blended with polycaprolactone for toughening and modification, and the obtained polylactic acid elastomer has good toughness and strength. By comparing Examples 2 and 3 with Example 1, it is found that the modification of epoxy silane coupling agent and the solubilization and toughening of cardanol acetate have significant synergistic effects; and after replacing the epoxy silane coupling agent with the coupling agent KH570 (Comparative Example 4) without epoxy group, its toughness, tensile strength and elongation at break are significantly reduced, and the selection of coupling agent plays an important role in improving the comprehensive performance of elastomer. In addition, the polylactic acid elastomer of Comparative Example 5 does not use a coupling agent to modify polylactic acid during the preparation process, but is prepared by a single blending. Although the toughness can achieve the effect equivalent to that of the embodiment, the tensile strength and elongation at break have decreased to varying degrees, indicating that the present invention achieves the toughening effect of polylactic acid through the selection of raw materials and the control of dosage, and further improves the strength of the material through the improvement of the preparation method.

[0076] Test Example 2: Degradation Performance Test

[0077] (1) Acid degradation experiment: The polylactic acid elastomer particles prepared in the comparative examples of the above embodiments were dried to constant weight, and the mass of the sample before degradation, m0, was weighed and recorded. Then, the sample was placed in a sample tube containing 10 mL of HCl (pH = 1) solution, and the acid degradation experiment was carried out in a constant temperature water bath at 37°C. Every 48 hours, the degraded sample was taken out, and the residual degradation liquid was rinsed with a large amount of distilled water, and then dried to constant weight, and the mass of the degraded sample, m, was weighed and recorded. t , repeat the above steps.

[0078] (2) Alkali degradation experiment: The polylactic acid elastomer particles prepared in the comparative examples of the above embodiments were dried to constant weight, and the mass of the sample before degradation was weighed and recorded m0. Then, the sample was placed in a sample tube containing 10 mL of NaOH (pH = 13) solution, and an alkaline degradation experiment was performed in a constant temperature water bath at 37°C. Every 48 hours, the degraded sample was taken out, and the residual degradation liquid was rinsed with a large amount of distilled water, and then dried to constant weight, and the mass of the degraded sample was weighed and recorded m0. t , repeat the above steps.

[0079] The degradation rate is calculated as follows:

[0080] Degradation rate = (m 0- m t ) / m0×100%

[0081] The 10-day degradation rate results of each polylactic acid elastomer particle are shown in Table 2.

[0082] Table 2

[0083]

[0084]

[0085] It can be seen from the above table that the polylactic acid elastomer particles prepared in the comparative examples of the embodiments of the present invention have good degradation performance under acidic and alkaline conditions, which is better than polylactic acid, but the degradation performance of Examples 1-5 is better, and the degradation performance improvement of Comparative Examples 1 and 3 is the lowest, among which, Comparative Example 1 may be caused by the small proportion of polycaprolactone; and Comparative Example 3 does not add cardanol acetate, which may have a certain impact on the degradation performance.

[0086] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A polylactic acid elastomer containing cardanol acetate, characterized in that: The polylactic acid elastomer is prepared from the following raw materials in parts by weight: 20-40 parts of polylactic acid, 5-20 parts of polycaprolactone, 0.01-0.05 parts of cardanol acetate and 0.01-0.45 parts of epoxy silane coupling agent.

2. The polylactic acid elastomer according to claim 1, characterized in that The polylactic acid elastomer is prepared from the following raw materials in parts by weight: 30-40 parts of polylactic acid, 5-10 parts of polycaprolactone, 0.02-0.05 parts of cardanol acetate and 0.01-0.05 parts of epoxy silane coupling agent.

3. The polylactic acid elastomer according to claim 2, characterized in that: The raw materials for preparing the polylactic acid elastomer are calculated by weight as follows: 40 parts of polylactic acid, 10 parts of polycaprolactone, 0.05 parts of cardanol acetate and 0.05 parts of epoxy silane coupling agent.

4. The polylactic acid elastomer according to claim 1, characterized in that: The cardanol acetate is epoxidized dicardanol carbonate, and the structure is as follows: Wherein, R1 and R2 are each independently selected from 5. The polylactic acid elastomer according to claim 4, characterized in that: The epoxy value of the epoxidized cardanol carbonate is 4-7%.

6. The polylactic acid elastomer according to claim 1, characterized in that: The total mass of the cardanol acetate and the epoxy silane coupling agent accounts for 0.05-0.2% of the total mass of the polylactic acid and the polycaprolactone.

7. The polylactic acid elastomer according to claim 1, characterized in that: The mass ratio of cardanol acetate to epoxy silane coupling agent is 1:1-5.

8. The method for preparing a polylactic acid elastomer according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Polylactic acid modification: adding epoxy silane coupling agent to polylactic acid, heating and modifying the polylactic acid to obtain modified polylactic acid; (2) Blending: Put polycaprolactone, epoxidized cardanol carbonate and modified polylactic acid into a twin-screw extruder for melt blending, and granulate them by extrusion to obtain the product.

9. The preparation method according to claim 8, characterized in that: In step (1), the heating temperature is 80-100°C and the time is 20-40min; in step (2), the feeding zone temperature of the twin-screw extruder is 90-120°C, the reaction zone temperature is 140-180°C, and the extrusion zone temperature is 240-160°C; the extrusion speed is 80-150r / min.

10. Use of the polylactic acid elastomer according to any one of claims 1 to 7 or the polylactic acid elastomer prepared by the preparation method according to claim 8 or 9 in drug transportation materials, agricultural mulch materials or food packaging materials.

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