Preparation method of maleated rosin urea complex toughened thermoplastic starch plastic

Abstract

The present invention relates to a preparation method of a maleic rosin urea complex toughened thermoplastic starch plastic, belonging to the field of biodegradable polymer materials. The method first reacts urea with maleic rosin to obtain a maleic rosin urea complex, and then blends it with starch and urea, and extrudes it through an extruder to obtain a thermoplastic starch plastic toughened based on the maleic rosin urea complex. The thermoplastic starch plastic can effectively improve the elongation at break (fracture toughness) of the thermoplastic starch plastic with a relatively small addition amount (0.5 to 2 parts) of the maleic rosin urea complex (based on 100 parts of starch), while maintaining a stable and high tensile strength; in addition, the overall material still remains completely biodegradable and is expected to be applied in the fields of packaging, disposable tableware and other disposable consumables.

Description

Technical Field

[0001] The present invention belongs to the field of biodegradable plastics and relates to a preparation method of a maleic rosin urea complex toughened thermoplastic starch plastic. Background Art

[0002] Vigorously developing bio-based and biodegradable plastics and reducing the use of petroleum-based plastics is one of the scientific and technological problems that need to be urgently solved in the development of human economy and society. As a biodegradable natural polymer, starch not only has advantages in terms of source and price, but also its renewable nature, environmental friendliness and biodegradability have enabled it to be widely used in the field of plastics. Preparing thermoplastic starch plastics by adding plasticizers to starch is one of the hotspots in domestic and foreign research and development. At present, the commonly used plasticizers in thermoplastic starch plastics are polyols and polyamines or amides. In comparison, polyamines or amides can form stronger hydrogen bonds with the hydroxyl groups on starch macromolecules, thus having higher tensile strength. However, the accompanying problem is that the thermoplastic starch plastic becomes brittle, that is, its toughness decreases, manifested as a significant reduction in the elongation at break.

[0003] To solve the above problems, the patent with the patent number CN105415828A discloses a preparation method of an elastic barrier environmental protection composite film. This composite film is composed of multiple layers of films, including a bottom starch elastic film, an intermediate layer polylactic acid strength elastic film, and an outer layer starch elastic film in sequence, having excellent strength and elasticity (toughness), as well as good heat insulation and waterproof properties, but the preparation method is relatively complex and the addition of polylactic acid is not conducive to cost reduction; the patent with the patent number CN102443194A discloses a thermoplastic starch plastic that can be well compatible with fossil-based materials. Using thermoplastic starch as the matrix and adding polymers such as polycarbonate and acrylonitrile-butadiene-styrene as toughening agents, the resulting composite material can replace a series of plastic parts of communication and communication technology products mainly based on petroleum-based plastics on the market. However, since the toughening agent is non-degradable, this material as a whole is still not completely degradable. Summary of the Invention

[0004] To solve the technical problem that in the prior art, while improving the strength of thermoplastic starch plastics, the brittleness of the material increases due to the reduction of the elongation at break, the inventor unexpectedly found that the maleic rosin urea complex, as a toughening agent, can well improve the toughness of thermoplastic starch plastics while maintaining a stable and high tensile strength. Based on the above discovery, the present invention was thus completed.

[0005] Therefore, the present invention first provides a preparation method of a maleic rosin urea complex.

[0006] The present invention also provides the application of the maleic rosin urea complex of the present invention as a toughening agent for thermoplastic starch plastics.

[0007] Specifically, the toughened thermoplastic starch plastic of the maleic rosin urea complex of the present invention is composed of the following components by weight ratio:

[0008] Starch 100

[0009] Urea 25 - 30

[0010] Maleic rosin urea complex 0.5 - 2

[0011] The specific method adopted by the present invention is as follows:

[0012] 1) Preparation of maleic rosin urea complex

[0013] Mix 15 - 25 parts of maleic rosin, 2 - 4 parts of urea and 250 parts of N,N - dimethylformamide (DMF) in a container, then heat up to 90°C. Add p - toluenesulfonic acid, which is 1.0% of the weight percentage of maleic rosin, as a catalyst in two stages, and heat up to 105 - 115°C. The total reaction time is 4 - 5 h. After the reaction is completed, cool to room temperature, add a large amount of ultrapure water, obtain a suspension and perform suction filtration. The obtained filter cake is dried at 40°C under normal pressure for 12 h to obtain the maleic rosin urea complex;

[0014] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0015] Then take 100 parts of starch, add 25 - 30 parts of urea and 0.5 - 2 parts of maleic rosin urea complex, and mix evenly; extrude and pelletize in a single - screw extruder, control the temperature of each zone at 120°C, and the rotation speed is 40 - 50 r / min; perform hot pressing at 120°C with a hot press to obtain the maleic rosin urea complex toughened thermoplastic starch plastic.

[0016] The advantages of the present invention are as follows:

[0017] 1) Natural rosin has a wide source and low cost, and the addition amount of the maleic rosin urea complex is small, which will not significantly increase the cost of the thermoplastic starch plastic, and has good market application prospects;

[0018] 2) The maleic rosin urea complex significantly improves the elongation at break of the thermoplastic starch plastic, while maintaining a stable and high tensile strength;

[0019] 3) The maleic rosin urea complex enables the thermoplastic starch plastic to still maintain completely biodegradable properties as a whole;

[0020] 4) The maleic rosin urea complex endows the thermoplastic starch plastic with certain antibacterial properties and can be used in fields such as food packaging. Description of the Drawings

[0021] Figure 1Preparation mechanism diagram of maleic rosin urea complex

[0022] Figure 2 Scanning electron micrographs of cross-sections of thermoplastic starch plastic films prepared in Examples 1, 2, 3, 4 and Comparative Examples 1 and 2

[0023] Note: The mechanical properties were tested according to the GB 1040-79 standard. The film size was 40×10×0.6 mm, the tensile rate was 50 mm / min, and the measurement was carried out using an MTS\SANS CMT4000 universal testing machine of MTS Industrial Systems (China) Co., Ltd. Detailed implementation manners

[0024] The present invention will be further understood from the following illustrative embodiments.

[0025] Example 1:

[0026] 1) Preparation of maleic rosin urea complex

[0027] Weigh 20 g of maleic rosin (model 115, purchased from Jiayu Chemical Factory in Yulin City, Guangxi), and dissolve 3 g of urea in 250 ml of N,N-dimethylformamide (DMF). Transfer the dissolved solution to a three-necked flask, heat it to 90 °C, add 0.1 g of p-toluenesulfonic acid as a catalyst, then raise the reaction temperature to 110 °C. After reacting for 2 h, add another 0.1 g of p-toluenesulfonic acid and continue reacting for 3 h. After the reaction is completed, wait for the solution to cool to room temperature. Take 20 ml of the reacted solution, add 80 ml of ultrapure water to obtain a suspension, and filter this suspension by suction. Repeat the above steps until the reacted solution is completely filtered by suction. Put the filter cake obtained by suction filtration into an oven at 40 °C and dry it for 12 h to obtain the maleic rosin urea complex;

[0028] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0029] Then take 100 g of starch, add 30 g of urea and 0.5 g of maleic rosin urea complex, and mix evenly. Extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed is 40 - 50 r / min. Carry out hot pressing at 120 °C with a hot press to obtain a maleic rosin urea complex toughened thermoplastic starch plastic film.

[0030] Example 2:

[0031] 1) Preparation of maleic rosin urea complex

[0032] The preparation method of the maleic rosin urea complex refers to the preparation method of the maleic rosin urea complex in Example 1;

[0033] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0034] Take another 100 g of starch, add 30 g of urea and 1 g of maleic rosin urea complex, and mix evenly; extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed is 40 - 50 r / min; perform hot pressing at 120 °C with a hot press to obtain a maleic rosin urea complex toughened thermoplastic starch plastic film.

[0035] Example 3:

[0036] 1) Preparation of maleic rosin urea complex

[0037] The preparation method of the maleic rosin urea complex refers to the preparation method of the maleic rosin urea complex in Example 1;

[0038] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0039] Take another 100 g of starch, add 30 g of urea and 1.5 g of maleic rosin urea complex, and mix evenly; extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed is 40 - 50 r / min; perform hot pressing at 120 °C with a hot press to obtain a maleic rosin urea complex toughened thermoplastic starch plastic film.

[0040] Example 4:

[0041] 1) Preparation of maleic rosin urea complex

[0042] The preparation method of the maleic rosin urea complex refers to the preparation method of the maleic rosin urea complex in Example 1;

[0043] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0044] Take another 100 g of starch, add 30 g of urea and 2 g of maleic rosin urea complex, and mix evenly; extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed is 40 - 50 r / min; perform hot pressing at 120 °C with a hot press to obtain a maleic rosin urea complex toughened thermoplastic starch plastic film.

[0045] Comparative Example 1: (Without adding maleic rosin urea complex)

[0046] Take 100 g of starch, add 30 g of urea, and mix evenly; extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed is 40 - 50 r / min; perform hot pressing at 120 °C with a hot press to obtain a urea-plasticized thermoplastic starch plastic film.

[0047] Comparative Example 2: (Adding 3 parts of maleic rosin urea complex)

[0048] 1) Preparation of maleic rosin urea complex

[0049] The preparation method of maleic rosin urea complex refers to the preparation method of maleic rosin urea complex in Example 1;

[0050] 2) Preparation of maleic rosin urea complex toughened thermoplastic starch plastic

[0051] Take another 100 g of starch, add 30 g of urea and 3 g of maleic rosin urea complex, and mix evenly; extrude and granulate in a single-screw extruder, control the temperature of each zone at 120 °C, and the rotation speed at 40 - 50 r / min; perform hot pressing under the condition of 120 °C with a hot press to obtain maleic rosin urea complex toughened thermoplastic starch plastic film.

[0052] Table 1

[0053]

[0054] The test data of the strength (tensile strength) and toughness (elongation at break) of each example and comparative example in Table 1 above show that the thermoplastic starch plastic film prepared by using 0.5 - 2 parts of maleic rosin urea complex (the preparation mechanism is shown in the appendix Figure 1 ) has significantly better toughness (elongation at break) than the thermoplastic starch plastic film of the comparative example, and can also maintain stable strength. The scanning electron microscope image of the fracture surface of the appendix Figure 2 further provides evidence, showing that 0.5 - 2 parts of maleic rosin urea complex can form a uniform and stable interaction with the thermoplastic starch matrix. Among them, the cross-section of Example 3 is significantly uneven, indicating good toughness, which is consistent with the data in Table 1.

Claims

1. A preparation method of a toughened thermoplastic starch plastic by maleated rosin urea complex, characterized in that: The toughened thermoplastic starch plastic with maleic rosin urea complex is obtained according to the following steps: 15-25 parts of maleic rosin, 2-4 parts of urea and 250 parts of N,N-dimethylformamide (DMF) are mixed in a container and then heated to 90 °C. Then, p-toluenesulfonic acid accounting for 1.0% of the weight percentage of maleic rosin is added in two stages as a catalyst, and the temperature is raised to 105-115 °C. The total reaction time is 4-5 h. After the reaction is completed, it is cooled to room temperature, a large amount of ultrapure water is added, and a suspension is obtained and filtered by suction. The obtained filter cake is dried at 40 °C under normal pressure for 12 h to obtain the maleic rosin urea complex; Then, 100 parts of starch, 30 parts of urea and 0.5-2 parts of the maleic rosin urea complex are taken and uniformly mixed. Extrusion granulation is carried out in a single-screw extruder, the temperature of each zone is controlled at 120 °C, and the rotation speed is 40-50 r / min; hot pressing is carried out at 120 °C with a hot press to obtain the toughened thermoplastic starch plastic with maleic rosin urea complex.

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