Bio-based polylactic acid compatilizer, preparation method thereof and full-bio-based polylactic acid composite material

Abstract

The invention belongs to the technical field of compatilizers, and relates to a bio-based polylactic acid compatilizer, a preparation method thereof and a full-bio-based polylactic acid composite material. The invention discloses a bio-based polylactic acid compatilizer and a preparation method thereof. The invention also discloses a full-bio-based polylactic acid composite material which comprises the following raw materials: polylactic acid, plant powder and / or plant fibers and a bio-based polylactic acid compatilizer. According to the invention, autonomously synthesized bio-based synthetic bio-based itaconic acid diglycidyl ester is adopted as a grafting monomer and is grafted with PLA as a bio-based source, and the obtained bio-based polylactic acid compatilizer has excellent compatibility; and the bio-based polylactic acid compatilizer is used for preparing the full-bio-based polylactic acid composite material, so that the interfacial compatibility and the mechanical property of the polylactic acid composite material can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of compatibilizers and relates to a bio-based polylactic acid compatibilizer and a preparation method thereof and a fully bio-based polylactic acid composite material. Background Art

[0002] Polylactic acid (PLA) is a new type of biodegradable material. It is derived from non-grain starch raw materials, which are saccharified to obtain glucose, and then fermented with glucose and certain strains of bacteria to produce high-purity lactic acid, and then synthesized into polylactic acid of a certain molecular weight through chemical synthesis. Polylactic acid has the mechanical strength and transparency of general plastics, and has the advantages of excellent biodegradability and biological sources. Therefore, it is widely used in the field of disposable products (such as disposable straws, lunch boxes and food packaging, etc.) and biomedicine (disposable infusion tools, non-disassembly surgical sutures, drug relief packaging agents, artificial fracture internal fixation materials, tissue repair materials and artificial skin, etc.).

[0003] However, polylactic acid materials have poor impact resistance, are easy to break, and their cost is more than double that of traditional plastics (such as polypropylene and polyethylene). Therefore, in actual use, it is often necessary to add toughening agents, plant fiber fillers or mineral fillers. However, after polylactic acid is compounded with these materials, problems such as component incompatibility leading to interface separation occur, which further causes the mechanical properties of the material to decline and fails to achieve the expected enhancement and toughening effect. In order to solve the compatibility problem, it is usually necessary to add polylactic acid compatibilizers. The most widely used polylactic acid compatibilizers are polylactic acid grafted maleic anhydride (MAH) compatibilizer (PLA-g-MAH) and polylactic acid grafted methacrylate glycidyl (GMA) compatibilizer (PLA-g-GMA). However, both of these compatibilizers have the disadvantages of low grafting rate, strong odor, unsatisfactory compatibilization effect and petroleum-based grafting monomers.

[0004] Therefore, it is very important to prepare a bio-based polylactic acid compatibilizer with high grafting rate and high epoxy value, and whose grafting monomer is derived from bio-based sources. This can not only improve the compatibility problems and performance of PLA composites, but also expand the application areas of polylactic acid. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and to propose a bio-based polylactic acid compatibilizer with bio-based diglycidyl itaconate as a grafting monomer. The materials are all bio-based, have a high epoxy value, and a weak tendency to self-polymerization. It can be dynamically grafted with polylactic acid and achieve a higher epoxy value and grafting rate. Its application in bio-based composite materials can greatly improve the interfacial compatibility and mechanical properties of the composite materials.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A bio-based polylactic acid compatibilizer, the structural formula of which is shown in the following formula (1):

[0008]

[0009] Here, n is an integer ranging from 1 to 10000.

[0010] Preferably, in the formula (1), n ​​is an integer ranging from 10 to 8000.

[0011] More preferably, in the formula (1), n ​​is an integer of 300 to 6000.

[0012] Preferably, the bio-based polylactic acid compatibilizer comprises the following raw materials in parts by weight: 100 parts of polylactic acid, 0.1 to 5 parts of peroxide initiator, and 1 to 20 parts of bio-based diglycidyl itaconate.

[0013] Further preferably, the bio-based polylactic acid compatibilizer comprises the following raw materials in parts by weight: 100 parts of polylactic acid, 0.15-0.75 parts of peroxide initiator, and 1-7 parts of bio-based diglycidyl itaconate.

[0014] More preferably, the raw materials of the bio-based polylactic acid compatibilizer include 100 parts of polylactic acid, 0.45-0.75 parts of peroxide initiator, and 3-7 parts of bio-based diglycidyl itaconate.

[0015] Preferably, the epoxy value of the bio-based polylactic acid compatibilizer is 0.2×10 -2 ~1.6×10 -2 The grafting rate is 0.3~1.9%.

[0016] More preferably, the epoxy value of the bio-based polylactic acid compatibilizer is 0.8×10 -2 ~1.5×10 -2 The grafting rate is 1.0~1.8%.

[0017] Preferably, the bio-based diglycidyl itaconate is prepared by mixing itaconic acid, epoxyhalopropane, a catalyst and an inhibitor, stirring at room temperature under the protection of an inert gas, heating to carry out a first reaction, then cooling to room temperature, adding alkaline solution dropwise and carrying out a second reaction, and then washing with water and distilling under reduced pressure to obtain the product.

[0018] Preferably, the structural formula of the bio-based diglycidyl itaconate is as shown in the following formula (2):

[0019]

[0020] Preferably, the mass ratio of itaconic acid, epihalopropane, catalyst and polymerization inhibitor is 100:(600-1000):(1-5):(0.1-0.5).

[0021] Preferably, the epihalohydrin is one or more of epichlorohydrin, epibromohydrin and epiiodohydrin.

[0022] Preferably, the catalyst includes one or more of tetramethylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium bromide, benzyltriethylammonium bromide, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, and hexamethylenetetrammonium.

[0023] Preferably, the polymerization inhibitor includes one or more of p-benzoquinone, p-hydroxyanisole, methylhydroquinone, 2-tert-butylhydroquinone, and 2,5-di-tert-butylhydroquinone.

[0024] Preferably, the alkali solution is a mixture of alkaline substances and water, and the alkali solution includes one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, calcium hydroxide aqueous solution, barium hydroxide aqueous solution, lithium hydroxide aqueous solution, sodium carbonate aqueous solution, and potassium carbonate aqueous solution.

[0025] Preferably, the mass percentage concentration of the alkali solution is 30-70%.

[0026] Preferably, the molar ratio of the alkaline substance to itaconic acid in the alkali solution is (1-5):1.

[0027] More preferably, the molar ratio of the alkaline substance to itaconic acid in the alkali solution is (2.2-2.8):1.

[0028] Preferably, the first reaction temperature is 60-150° C., and the reaction time is 0.1-10 h.

[0029] Preferably, the second reaction temperature is 10-40° C. and the reaction time is 0.1-10 h.

[0030] Preferably, the preparation method of bio-based diglycidyl itaconate comprises:

[0031] (1) 100 parts of itaconic acid, 600-1000 parts of epichlorohydrin, 1-5 parts of a catalyst and 0.1-0.5 parts of p-hydroxyanisole are uniformly mixed, and then vigorously stirred at room temperature for 10-60 minutes under the protection of an inert gas, and then heated to carry out a first reaction, wherein the first reaction temperature is 60-150° C. and the reaction time is 0.1-10 hours, to obtain A;

[0032] (2) cooling A to room temperature, adding dropwise an alkali solution with a mass percentage concentration of 30-70%, and performing a second reaction at a temperature of 10-40° C. for a time of 0.1-10 h to obtain B;

[0033] (3) After washing B with water, it is distilled under reduced pressure at 90-150° C. to obtain bio-based diglycidyl itaconate.

[0034] Preferably, the preparation method of bio-based diglycidyl itaconate comprises:

[0035] (1) 100 parts of itaconic acid, 600-1000 parts of epihalopropane, 1-5 parts of tetrabutylammonium bromide and 0.1-0.5 parts of p-hydroxyanisole are mixed uniformly, and then stirred vigorously at room temperature for 10-60 minutes under the protection of an inert gas, and then heated to carry out a first reaction, wherein the first reaction temperature is 80-120° C. and the reaction time is 1-5 hours, to obtain A;

[0036] (2) cooling A to room temperature, adding a sodium hydroxide aqueous solution with a mass percentage concentration of 40-60% dropwise, and performing a second reaction at a temperature of 10-40° C. for 1-5 h to obtain B;

[0037] (3) After washing B with water, it is distilled under reduced pressure at 90-150° C. to obtain bio-based diglycidyl itaconate.

[0038] More preferably, the second reaction temperature in (2) is the same as room temperature, which is 10 to 40°C.

[0039] More preferably, in said (2), the room temperature is 20-30°C, and the second reaction temperature is 20-30°C.

[0040] Preferably, the peroxide initiator includes one or more of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), 1,4-di-tert-butylperoxyisopropylbenzene (BIBP) and tert-butyl peroxyacetate (TBPA).

[0041] A method for preparing a bio-based polylactic acid compatibilizer comprises:

[0042] (1) Weigh the raw materials according to the following weight parts: 100 parts of polylactic acid, 0.1-5 parts of peroxide initiator, and 1-20 parts of bio-based diglycidyl itaconate;

[0043] (2) The raw materials in (1) are mixed and added into a twin-screw extruder for melt blending and dynamic grafting reaction extrusion.

[0044] Preferably, the (1) comprises the following raw materials in parts by weight: 100 parts of polylactic acid, 0.15-0.75 parts of peroxide initiator, and 1-7 parts of bio-based diglycidyl itaconate.

[0045] Preferably, the bio-based itaconic acid diglycidyl ester in (1) is prepared by mixing itaconic acid, epoxyhalopropane, a catalyst and an inhibitor, stirring vigorously at room temperature under the protection of an inert gas, heating to carry out a first reaction, then cooling to room temperature, adding alkaline solution dropwise and carrying out a second reaction, and then washing with water and distilling under reduced pressure to obtain the product.

[0046] Preferably, the length-to-diameter ratio of the twin-screw extruder in (2) is (40-60):1, the screw speed is 100-600 rpm, and the extrusion temperature is 160-185°C.

[0047] Further preferably, the extrusion temperature is 160-185°C, the temperature of zone one is 160°C, the temperature of zone two is 170°C, the temperature of zone three is 175°C, the temperature of zone four is 180°C, the temperature of zone five is 185°C, the temperature of zone six is ​​185°C, the temperature of zone seven is 185°C, the temperature of zone eight is 185°C, the temperature of zone nine is 180°C, the temperature of zone ten is 180°C, and the temperature of zone eleven is 175°C.

[0048] Preferably, in (2), the extrusion is followed by cooling, pelletizing and homogenization.

[0049] A fully bio-based polylactic acid composite material, whose raw materials include 100 parts of polylactic acid, 1 to 50 parts of plant powder and / or plant fiber, and 0.1 to 10 parts of a bio-based polylactic acid compatibilizer.

[0050] Preferably, the plant powder includes one or more of bamboo powder, starch, and plant ash; and the plant fiber includes one or more of coconut fiber, straw fiber, and rice husk fiber powder.

[0051] Preferably, the raw material of the all-biobased polylactic acid composite material further includes 1 to 10 parts of an auxiliary agent, and the auxiliary agent includes epoxidized soybean oil.

[0052] Preferably, the impact strength of the all-biobased polylactic acid composite material is greater than 3.5 KJ / cm 2 , tensile strength>55MPa, flexural strength>82MPa.

[0053] Further preferably, the impact strength of the all-biobased polylactic acid composite material is ≥4.2KJ / cm 2 , tensile strength ≥57MPa, flexural strength ≥85MPa.

[0054] A method for preparing a fully bio-based polylactic acid composite material comprises: mixing raw materials, adding the raw materials to a twin-screw extruder, and performing melt blending, extrusion and granulation.

[0055] Preferably, the melt blending extrusion temperature is 60-195° C., the screw speed is 100-600 rpm, and the main feeding speed is 20-80 rpm.

[0056] Further preferably, the extrusion temperature is 90-180°C, the temperature of zone one is 90°C, the temperature of zone two is 100°C, the temperature of zone three is 170°C, the temperature of zone four is 175°C, the temperature of zone five is 180°C, the temperature of zone six is ​​180°C, the temperature of zone seven is 180°C, the temperature of zone eight is 180°C, the temperature of zone nine is 175°C, the temperature of zone ten is 175°C, and the temperature of zone eleven is 170°C.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The present invention uses independently synthesized bio-based synthetic bio-based itaconate diglycidyl ester as a grafting monomer, which is grafted with PLA as a bio-based source, and the obtained bio-based polylactic acid compatibilizer has excellent compatibility;

[0059] 2. In the process of independently synthesizing bio-based diglycidyl itaconate EIA, the present invention does not need to add organic solvents or other organic compounds, and the prepared EIA is more environmentally friendly and easy to degrade;

[0060] 3. The bio-based synthetic bio-based itaconate diglycidyl ester synthesized independently by the present invention has a high epoxy value. Due to the presence of the diepoxy structure, its double bond is not easy to homopolymerize compared with GMA, and is more inclined to graft with PLA, thereby increasing the grafting rate;

[0061] 4. Compared with the existing PLA-g-MAH and PLA-g-GMA, the bio-based polylactic acid compatibilizer of the present invention has a higher grafting rate and more compatible groups (epoxy groups), which greatly improves the interfacial compatibility of the polylactic acid composite material;

[0062] 5. The bio-based polylactic acid compatibilizer of the present invention can be used to prepare all-bio-based polylactic acid composite materials. Under the action of the bio-based polylactic acid compatibilizer, polylactic acid is mixed with other bio-based polymers, which has better interface bonding and compatibility, and can improve the interface compatibility and mechanical properties of the polylactic acid composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1The graphs are of epoxy value and grafting rate of the bio-based polylactic acid compatibilizers prepared in Examples 4 to 11 of the present invention and the compatibilizer prepared in Comparative Example 1; wherein Figure (a) is a graph of epoxy value and grafting rate of the bio-based polylactic acid compatibilizers prepared with different amounts of initiator added in Examples 4 to 8 and the compatibilizer prepared in Comparative Example 1, and Figure (b) is a graph of epoxy value and grafting rate of the bio-based polylactic acid compatibilizers prepared with different amounts of grafting monomer added in Examples 6 and 9 to 11 and the compatibilizer prepared in Comparative Example 1.

[0064] Figure 2 The impact strength trend diagrams of Application Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention with different contents of EIA-g-PLA and different contents of GMA-g-PLA added are shown.

[0065] Figure 3 The tensile strength and tensile modulus trend diagrams of Application Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention with different contents of EIA-g-PLA and different contents of GMA-g-PLA added are shown.

[0066] Figure 4 The flexural strength and flexural modulus trend diagrams of Application Examples 1 to 5 and Comparative Examples 1 to 4 of the present invention with different contents of EIA-g-PLA and different contents of GMA-g-PLA added are shown. DETAILED DESCRIPTION

[0067] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0068] Unless otherwise specified, the materials used in the present invention are conventional commercial products, and the methods used are conventional technical means.

[0069] Example 1

[0070] Preparation method of bio-based diglycidyl itaconate:

[0071] According to the mass fractions, 100 parts of itaconic acid, 600 parts of epichlorohydrin, 1 part of tetrabutylammonium bromide and 0.1 part of p-hydroxyanisole were mixed evenly, and under the protection of inert gas, the mixture was vigorously stirred for 20 minutes at room temperature, and then the temperature was raised to the first reaction temperature of 90°C for reaction for 3 hours; then the temperature was lowered to 25°C, and a 50% mass concentration of sodium hydroxide aqueous solution was added dropwise, wherein the amount of sodium hydroxide in the sodium hydroxide aqueous solution was 2.4 times the molar fraction of itaconic acid, and the mixture was reacted at 25°C for 3 hours; the mixture was washed with water, and distilled under reduced pressure at 110°C to obtain bio-based diglycidyl itaconic acid, which was recorded as EIA-1.

[0072] Example 2

[0073] Preparation method of bio-based diglycidyl itaconate:

[0074] According to the mass fractions, 100 parts of itaconic acid, 800 parts of epichlorohydrin, 3 parts of tetrabutylammonium bromide and 0.3 parts of p-hydroxyanisole were mixed evenly, and then vigorously stirred at room temperature for 20 minutes under the protection of inert gas, and then the temperature was raised to the first reaction temperature of 90°C for reaction for 3 hours; then the temperature was lowered to room temperature of 25°C, and a 50% mass concentration of sodium hydroxide aqueous solution was added dropwise, the amount of sodium hydroxide in the sodium hydroxide aqueous solution was 2.4 times the molar fraction of itaconic acid, and the reaction was carried out at 25°C for 3 hours; washed with water, and distilled under reduced pressure at 110°C to obtain bio-based diglycidyl itaconic acid, which was recorded as EIA-2.

[0075] Example 3

[0076] Preparation method of bio-based diglycidyl itaconate:

[0077] According to the mass fractions, 100 parts of itaconic acid, 1000 parts of epichlorohydrin, 5 parts of tetrabutylammonium bromide and 0.5 parts of p-hydroxyanisole were mixed evenly, and then under the protection of inert gas, the mixture was vigorously stirred for 20 minutes at room temperature, and then the temperature was raised to the first reaction temperature of 90°C for reaction for 3 hours; then the temperature was lowered to 25°C at room temperature, and a 50% mass concentration of sodium hydroxide aqueous solution was added dropwise, wherein the amount of sodium hydroxide in the sodium hydroxide aqueous solution was 2.4 times the molar fraction of itaconic acid, and the mixture was reacted at 25°C for 3 hours; the mixture was washed with water, and distilled under reduced pressure at 110°C to obtain bio-based diglycidyl itaconic acid, which was recorded as EIA-3.

[0078] Example 4

[0079] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0080] According to the mass proportions, 100 parts of polylactic acid, 0.15 parts of DCP and 3 parts of EIA-2 were mixed evenly, and then added into a twin-screw extruder for melt blending reaction extrusion, wherein the extrusion temperature was 160-185°C, the temperature of zone 1 was 160°C, the temperature of zone 2 was 170°C, the temperature of zone 3 was 175°C, the temperature of zone 4 was 180°C, the temperature of zone 5-8 was 185°C, the temperature of zone 9-10 was 180°C, the temperature of zone 11 was 175°C, the screw speed was 300rpm, and the feeding speed was 20rpm; the screw length-diameter ratio used in the twin-screw melt extrusion was 52:1; and a bio-based polylactic acid compatibilizer was prepared.

[0081] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-1, and its epoxy value and grafting rate are shown in Table 1.

[0082] Example 5

[0083] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0084] According to the weight percentage, 100 parts of polylactic acid, 0.3 parts of DCP and 3 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0085] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-2, and its epoxy value and grafting rate are shown in Table 1.

[0086] Example 6

[0087] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0088] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DCP and 3 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0089] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-3, and its epoxy value and grafting rate are shown in Table 1.

[0090] Example 7

[0091] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0092] According to the weight percentage, 100 parts of polylactic acid, 0.6 parts of DCP and 3 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0093] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-4, and its epoxy value and grafting rate are shown in Table 1.

[0094] Example 8

[0095] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0096] According to the weight percentage, 100 parts of polylactic acid, 0.75 parts of DCP and 3 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0097] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-5, and its epoxy value and grafting rate are shown in Table 1.

[0098] Example 9

[0099] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0100] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DCP and 1 part of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0101] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-6, and its epoxy value and grafting rate are shown in Table 1.

[0102] Example 10

[0103] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0104] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DCP and 5 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0105] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-7, and its epoxy value and grafting rate are shown in Table 1.

[0106] Embodiment 11

[0107] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0108] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DCP and 7 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0109] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-8, and its epoxy value and grafting rate are shown in Table 1.

[0110] Example 12

[0111] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0112] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DTBP and 3 parts of EIA-1 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0113] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-9, and its epoxy value and grafting rate are shown in Table 1.

[0114] Embodiment 13

[0115] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0116] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of BIBP and 3 parts of EIA-2 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0117] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-10, and its epoxy value and grafting rate are shown in Table 1.

[0118] Embodiment 14

[0119] Preparation method of bio-based polylactic acid compatibilizer (EIA-g-PLA):

[0120] According to the weight percentages, 100 parts of polylactic acid, 0.45 parts of TBPA and 3 parts of EIA-3 were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0121] The bio-based polylactic acid compatibilizer obtained in this example is recorded as EIA-g-PLA-11, and its epoxy value and grafting rate are shown in Table 1.

[0122] Comparative Example 1

[0123] Preparation method of bio-based polylactic acid compatibilizer (GMA-g-PLA):

[0124] According to the weight percentage, 100 parts of polylactic acid, 0.45 parts of DCP and 3 parts of GMA were uniformly mixed, and then melt-blended and extruded according to the method in Example 4 to obtain a bio-based polylactic acid compatibilizer.

[0125] The bio-based polylactic acid compatibilizer obtained in this comparative example is recorded as GMA-g-PLA, and its epoxy value and grafting rate are shown in Table 1.

[0126] Application Example 1

[0127] Preparation method of PLA / bamboo powder composite material:

[0128] According to the mass fraction, 98.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 1.25 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were mixed uniformly, and then added into a twin-screw extruder for melt blending and extrusion, the extrusion temperature was 90-180°C, the temperature of zone 1 was 90°C, the temperature of zone 2 was 100°C, the temperature of zone 3 was 170°C, the temperature of zone 4 was 175°C, the temperature of zone 5 was 180°C, the temperature of zone 6 was 180°C, the temperature of zone 7 was 180°C, the temperature of zone 8 was 180°C, the temperature of zone 9 was 175°C, the temperature of zone 10 was 175°C, the temperature of zone 11 was 170°C, the screw speed was 300rpm, and the feeding speed was 15rpm; a PLA / bamboo powder composite material was prepared, which was recorded as E-1.

[0129] The properties of the PLA / bamboo powder composite material prepared in this application example are shown in Table 2.

[0130] Application Example 2

[0131] Preparation method of PLA / bamboo powder composite material:

[0132] According to the weight percentage, 96.25 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 3.75 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were mixed evenly, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as E-3.

[0133] The properties of the PLA / bamboo powder composite material prepared in this application example are shown in Table 2.

[0134] Application Example 3

[0135] Preparation method of PLA / bamboo powder composite material:

[0136] According to the mass proportions, 93.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 6.25 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were uniformly mixed, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as E-5.

[0137] The properties of the PLA / bamboo powder composite material prepared in this application example are shown in Table 2.

[0138] Application Example 4

[0139] Preparation method of PLA / bamboo powder composite material:

[0140] According to the mass fractions, 91.25 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 8.75 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were mixed uniformly, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as E-7.

[0141] The properties of the PLA / bamboo powder composite material prepared in this application example are shown in Table 2.

[0142] Application Example 5

[0143] Preparation method of PLA / bamboo powder composite material:

[0144] According to the mass proportions, 88.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 11.25 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were uniformly mixed, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as E-9.

[0145] The properties of the PLA / bamboo powder composite material prepared in this application example are shown in Table 2.

[0146] Application Example 6

[0147] Preparation method of PLA / rice husk fiber powder composite material:

[0148] According to the weight proportions, 88.75 parts of polylactic acid, 25 parts of rice husk fiber powder (200 mesh), 11.25 parts of EIA-g-PLA-3 (Example 6) and 1.25 parts of epoxidized soybean oil were uniformly mixed, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / rice husk fiber powder composite material, which was recorded as E-9'.

[0149] The impact strength of the PLA / rice husk fiber powder composite material prepared in this application example is 4.51 KJ / cm 2 , tensile strength 61.23MPa, flexural strength 86.71MPa.

[0150] Application Comparative Example 1

[0151] Preparation method of PLA / bamboo powder composite material:

[0152] According to the weight percentage, 100 parts of polylactic acid, 25 parts of bamboo powder (400 mesh) and 1.25 parts of epoxidized soybean oil were mixed evenly, and then melt-blended and extruded according to the method in Application Example 1 to prepare a PLA / bamboo powder composite material, which was recorded as BP20.

[0153] The properties of the PLA / bamboo powder composite material prepared in this application comparative example are shown in Table 2.

[0154] Application Comparative Example 2

[0155] Preparation method of PLA / bamboo powder composite material:

[0156] 98.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 1.25 parts of GMA-g-PLA (Comparative Example 1) and 1.25 parts of epoxidized soybean oil were mixed uniformly according to their mass fractions, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as G-1.

[0157] The properties of the PLA / bamboo powder composite material prepared in this application comparative example are shown in Table 2.

[0158] Application Comparative Example 3

[0159] Preparation method of PLA / bamboo powder composite material:

[0160] 93.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 6.25 parts of GMA-g-PLA (Comparative Example 1) and 1.25 parts of epoxidized soybean oil were mixed uniformly according to their mass fractions, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as G-5.

[0161] The properties of the PLA / bamboo powder composite material prepared in this application comparative example are shown in Table 2.

[0162] Application Comparative Example 4

[0163] Preparation method of PLA / bamboo powder composite material:

[0164] 88.75 parts of polylactic acid, 25 parts of bamboo powder (400 mesh), 11.25 parts of GMA-g-PLA (Comparative Example 1) and 1.25 parts of epoxidized soybean oil were mixed uniformly according to their mass fractions, and then melt-blended and extruded according to the method in Application Example 1 to obtain a PLA / bamboo powder composite material, which was recorded as G-9.

[0165] The properties of the PLA / bamboo powder composite material prepared in this application comparative example are shown in Table 2.

[0166] Table 1. EIA epoxy value and epoxy value and grafting rate data of bio-based polylactic acid compatibilizer

[0167]

[0168]

[0169] Table 2. Performance data of PLA / bamboo powder composite materials

[0170]

[0171] According to Table 1, by adjusting the addition amount of catalyst and p-hydroxyanisole in Examples 1 to 3 of the present invention, EIA with an epoxy value close to the theoretical epoxy value of EIA can be synthesized. In addition, the bio-based polylactic acid compatibilizer prepared by using the bio-based synthetic bio-based itaconate diglycidyl ester synthesized independently by the present invention as a grafting monomer has a high epoxy value and a good grafting rate.

[0172] Figure 1a is a graph showing the epoxy value and grafting rate of the bio-based polylactic acid compatibilizers prepared with different amounts of initiator added in Examples 4 to 8 and the compatibilizer prepared in Comparative Example 1. It can be seen that as the amount of initiator increases, the epoxy value and grafting rate of the prepared EIA-g-PLA first increase, and then remain at a stable level; compared with Comparative Example 1, it is found that after EIA is used as a grafting monomer and grafted with PLA, both the grafting rate and the epoxy value are significantly higher than those of GMA as a grafting monomer and grafted with PLA.

[0173] Figure 1 b is the graph showing the epoxy value and grafting rate of the bio-based polylactic acid compatibilizers prepared with different amounts of grafting monomer added in Examples 6 and 9-11 and the compatibilizer prepared in Comparative Example 1. It can be seen that with the increase in the amount of EIA added, the grafting rate and epoxy value of the prepared EIA-g-PLA gradually increase. When the amount of EIA added is 7 parts, the epoxy value is as high as 1.4863×10 -2 , the grafting rate is as high as 1.7984.

[0174] It can be seen from Examples 12 to 14 that when the initiator is changed from DCP to DTBP, BIBP and TBPA, the prepared EIA-g-PLA still has a relatively high epoxy value and grafting rate.

[0175] According to Table 2 above, the all-biobased composite material to which the bio-based polylactic acid compatibilizer of the present invention is added can effectively improve the impact strength, tensile strength, tensile modulus, flexural strength and flexural modulus of the composite material.

[0176] Figures 2 to 4 The impact strength trend graph, tensile strength and tensile modulus trend graph, flexural strength and flexural modulus trend graph of different contents of EIA-g-PLA and different contents of GMA-g-PLA are shown in Application Examples 1 to 5 and Application Comparative Examples 1 to 4. It can be seen that the performance of the composite materials in Application Examples 1 to 5 is significantly better than that in Application Comparative Example 1 without adding a compatibilizer and in Application Comparative Examples 2 to 4 using GMA-g-PLA as a compatibilizer.

[0177] In summary, the bio-based synthetic bio-based diglycidyl itaconate synthesized independently by the present invention is used as a grafting monomer and grafted with PLA as a bio-based source, and the obtained bio-based polylactic acid compatibilizer has excellent compatibility; and the bio-based polylactic acid compatibilizer of the present invention can be used to prepare all-bio-based polylactic acid composite materials. Under the action of the bio-based polylactic acid compatibilizer, polylactic acid is mixed with other bio-based polymers, has better interface bonding and compatibility, and can improve the interface compatibility and mechanical properties of the polylactic acid composite materials.

[0178] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A bio-based polylactic acid compatibilizer, characterized in that: Its structural formula is shown in the following formula (1): Here, n is an integer ranging from 1 to 10000.

2. The bio-based polylactic acid compatibilizer according to claim 1, characterized in that: The bio-based polylactic acid compatibilizer comprises the following raw materials in parts by weight: 100 parts of polylactic acid, 0.1 to 5 parts of peroxide initiator, and 1 to 20 parts of bio-based diglycidyl itaconate.

3. The bio-based polylactic acid compatibilizer according to claim 1, characterized in that: The bio-based diglycidyl itaconate is prepared by mixing itaconic acid, epoxyhalopropane, a catalyst and a polymerization inhibitor, stirring at room temperature under the protection of an inert gas, heating to carry out a first reaction, then cooling to room temperature, dropping an alkali solution and carrying out a second reaction, and then washing with water and distilling under reduced pressure to obtain the product.

4. The bio-based polylactic acid compatibilizer according to claim 3, characterized in that: The epihalohydrin is one or more of epichlorohydrin, epibromohydrin, and epiiodohydrin; the catalyst includes one or more of tetramethylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium bromide, benzyltriethylammonium bromide, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, and hexamethylenetetramonium; the inhibitor includes one or more of p-benzoquinone, p-hydroxyanisole, methylhydroquinone, 2-tert-butylhydroquinone, and 2,5-di-tert-butylhydroquinone.

5. The bio-based polylactic acid compatibilizer according to claim 3, characterized in that: The alkali solution is a mixture of an alkaline substance and water, and the molar ratio of the alkaline substance to itaconic acid in the alkali solution is (1-5):

1.

6. A method for preparing a bio-based polylactic acid compatibilizer, characterized in that: include: (1) Weigh the raw materials according to the following weight parts: 100 parts of polylactic acid, 0.1-5 parts of peroxide initiator, and 1-20 parts of bio-based diglycidyl itaconate; (2) The raw materials in (1) are mixed and added into a twin-screw extruder for melt blending and dynamic grafting reaction extrusion.

7. A fully bio-based polylactic acid composite material, characterized in that: The raw materials include 100 parts of polylactic acid, 1 to 50 parts of plant powder and / or plant fiber, and 0.1 to 10 parts of the bio-based polylactic acid compatibilizer as described in any one of claims 1 to 5 and / or the bio-based polylactic acid compatibilizer prepared by the preparation method of the bio-based polylactic acid compatibilizer as described in claim 6.

8. The all-biobased polylactic acid composite material according to claim 7, characterized in that: The plant powder includes one or more of bamboo powder, starch, and plant ash; the plant fiber includes one or more of coconut fiber, straw fiber, and rice husk fiber.

9. The all-biobased polylactic acid composite material according to claim 7, characterized in that: The raw materials also include auxiliary agents.

10. A method for preparing the all-biobased polylactic acid composite material according to claim 7, characterized in that: include: After the raw materials are mixed, they are added to a twin-screw extruder for melt blending and extrusion granulation.

Images