Degradable water-soluble packaging bag and preparation method thereof

Abstract

The invention discloses a degradable water-soluble packaging bag and a preparation method thereof, and belongs to the technical field of material engineering. The polylactic acid-phosphatidylserine composite material comprises the following raw material components in parts by weight: 20-30 parts of polylactic acid, 10-20 parts of phosphatidylserine, 10-15 parts of modified cellulose, 1-5 parts of a solubilizer and 1-5 parts of a plasticizer. The prepared product has excellent stability in a normal-temperature environment, has the characteristics of high degradation speed and no pollution to the environment, also has excellent comprehensive mechanical properties, and can meet the requirements of plastic products such as garbage bags, packaging bags and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of material engineering, and in particular relates to a degradable water-soluble packaging bag and a preparation method thereof. Background Art

[0002] Plastic packaging bags are made of plastic as raw materials and are used to produce various daily necessities. They are widely used in daily life and industrial production. Plastic packaging bags are consumables in daily life, and a large number of plastic shopping bags are consumed every year. Plastic bags can be divided into many types according to their uses, such as shopping bags, packaging bags, garbage bags, document bags, fresh-keeping bags, etc. Nowadays, the daily demand for plastic bags is huge, especially plastic packaging bags are used in large quantities with the popularity of online shopping, but the environmental pollution problems caused by this are also attracting more and more attention.

[0003] Degradable plastics have the traditional properties of plastics such as high stability, high toughness and plasticity. At the same time, they can be naturally degraded in the environment through light, heat, water, oxidation, biology and other means, and have little impact on the environment. Therefore, they have become a hot research direction for new packaging materials, such as plastic bags made of polyvinyl alcohol and polylactic acid degradable plastics. However, various additives are required in the preparation process of various types of plastic bags, and the addition of additives will lead to a decrease in the degradation performance of degradable plastics. Therefore, it is necessary to develop a new type of degradable packaging bag. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a degradable water-soluble packaging bag and a preparation method thereof, which can effectively improve the degradation performance and toughness of the packaging bag.

[0005] To achieve the above purpose, the technical solution adopted by the present invention to solve the technical problem is:

[0006] The object of the present invention is to provide a degradable water-soluble packaging bag, comprising the following raw material components in parts by weight:

[0007] 20-30 parts of polylactic acid, 10-20 parts of phosphatidylserine, 10-15 parts of modified cellulose, 1-5 parts of solubilizer and 1-5 parts of plasticizer.

[0008] Further, the raw material components include the following parts by weight:

[0009] 25-30 parts of polylactic acid, 15-20 parts of phosphatidylserine, 10-15 parts of modified cellulose, 1-5 parts of solubilizer and 1-3 parts of plasticizer.

[0010] Further, the raw material components include the following parts by weight:

[0011] 30 parts of polylactic acid, 15 parts of phosphatidylserine, 15 parts of modified cellulose, 2 parts of solubilizer and 3 parts of plasticizer.

[0012] Furthermore, cellulose is modified by pyrolysis to obtain modified cellulose. The specific process is as follows:

[0013] The cellulose is crushed into a particle size of 80-120 meshes, then heat-treated at 100-150°C for 30-50 minutes, and then heated to 200-250°C for further heat treatment for 20-30 minutes to obtain modified cellulose.

[0014] Furthermore, the first heat treatment temperature is 120-150°C, and the second heat treatment temperature is 200-220°C.

[0015] Furthermore, the first heat treatment time is 42 minutes, and the second heat treatment time is 25 minutes.

[0016] Furthermore, the plasticizer is glycerol.

[0017] Furthermore, the solubilizing agent is sodium salicylate.

[0018] Another object of the present invention is to provide a method for preparing the above-mentioned degradable water-soluble packaging bag, comprising the following steps:

[0019] (1) drying and sterilizing the modified cellulose for later use;

[0020] (2) After mixing polylactic acid, phosphatidylserine, a solubilizer and a plasticizer, water is added and stirred evenly, and the mixture is heated to 50 to 60° C. and stirred and mixed for 20 to 30 minutes to obtain a mixed suspension;

[0021] (3) adding the modified cellulose treated in step (1) to the mixed suspension obtained in step (2), stirring and mixing, and then forming a film and making a bag to obtain the degradable water-soluble packaging bag.

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention uses pyrolysis to modify cellulose. After pyrolysis modification at 100-250°C, a large number of hydroxyl groups will be generated, which can effectively promote the aggregation of microorganisms to improve the degradation efficiency of polylactic acid. The hydroxyl functional group can also hydrogen bond and van der Waals force with proteins on the surface of microorganisms, affecting the conformation and enzyme activity of microorganisms, thereby regulating and improving the metabolic activity of microorganisms. In addition, the pore structure of cellulose after pyrolysis treatment gives it a large specific surface area, good air permeability and water retention, which can provide a suitable growth environment for microorganisms and further promote the degradation of polylactic acid.

[0024] 2. Phosphatidylserine can promote the formation of biofilms by microorganisms on solid surfaces. Biofilm is a complex structure composed of microbial cells, extracellular polymers and water. It can provide a protective microenvironment for microorganisms and promote material exchange and information transmission between microorganisms. By forming biofilms, microorganisms can better adapt to environmental changes, improve their survival ability and polylactic acid degradation efficiency. In combination with modified cellulose, it can significantly improve the degradation efficiency of packaging bags.

[0025] 3. Water-soluble degradable plastics prepared using polylactic acid are slightly insufficient in terms of strength and durability. The present invention adds phosphatidylserine and modified cellulose to the raw materials. Phosphatidylserine can also stabilize the dispersion system in the system through emulsification, which can significantly improve the toughness of the product. At the same time, the added modified cellulose can also cooperate with phosphatidylserine to further improve the mechanical properties of the prepared packaging bag. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described below to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0027] Embodiment 1:

[0028] A degradable water-soluble packaging bag comprises the following raw material components in parts by weight:

[0029] 30 parts of polylactic acid, 15 parts of phosphatidylserine, 15 parts of modified cellulose, 2 parts of sodium salicylate and 3 parts of glycerol.

[0030] Among them, cellulose is modified by pyrolysis to obtain modified cellulose. The specific process is as follows:

[0031] The cellulose was crushed to a particle size of 120 mesh, then heat treated at 150°C for 42 minutes, and then heated to 220°C for a further 25 minutes to obtain modified cellulose.

[0032] The method for preparing the above-mentioned degradable water-soluble packaging bag comprises the following steps:

[0033] (1) drying and sterilizing the modified cellulose for later use;

[0034] (2) After mixing polylactic acid, phosphatidylserine, a solubilizer and a plasticizer, water is added and stirred evenly, and the mixture is heated to 50° C. and stirred and mixed for 30 minutes to obtain a mixed suspension;

[0035] (3) adding the modified cellulose treated in step (1) to the mixed suspension obtained in step (2), stirring and mixing, adding the mixture to a film blowing machine, blowing the film, and then using a bag making machine to obtain the degradable water-soluble packaging bag.

[0036] Embodiment 2:

[0037] A degradable water-soluble packaging bag comprises the following raw material components in parts by weight:

[0038] 20 parts of polylactic acid, 10 parts of phosphatidylserine, 10 parts of modified cellulose, 1 part of sodium salicylate and 1 part of glycerol.

[0039] Among them, cellulose is modified by pyrolysis to obtain modified cellulose. The specific process is as follows:

[0040] The cellulose was crushed to a particle size of 80 mesh, then heat treated at 100°C for 50 minutes, and then heated to 250°C for further heat treatment for 20 minutes to obtain modified cellulose.

[0041] The method for preparing the above-mentioned degradable water-soluble packaging bag comprises the following steps:

[0042] (1) drying and sterilizing the modified cellulose for later use;

[0043] (2) After mixing polylactic acid, phosphatidylserine, a solubilizer and a plasticizer, water is added and stirred evenly, and the mixture is heated to 60° C. and stirred and mixed for 20 minutes to obtain a mixed suspension;

[0044] (3) adding the modified cellulose treated in step (1) to the mixed suspension obtained in step (2), stirring and mixing, adding the mixture to a film blowing machine, blowing the film, and then using a bag making machine to obtain the degradable water-soluble packaging bag.

[0045] Embodiment 3:

[0046] A degradable water-soluble packaging bag comprises the following raw material components in parts by weight:

[0047] 25 parts of polylactic acid, 20 parts of phosphatidylserine, 10 parts of modified cellulose, 5 parts of sodium salicylate and 5 parts of glycerol.

[0048] Among them, cellulose is modified by pyrolysis to obtain modified cellulose. The specific process is as follows:

[0049] The cellulose was crushed to a particle size of 100 mesh, then heat treated at 120°C for 40 minutes, and then heated to 200°C for a further 30 minutes to obtain modified cellulose.

[0050] The method for preparing the above-mentioned degradable water-soluble packaging bag comprises the following steps:

[0051] (1) drying and sterilizing the modified cellulose for later use;

[0052] (2) After mixing polylactic acid, phosphatidylserine, a solubilizer and a plasticizer, water is added and stirred evenly, and the mixture is heated to 50° C. and stirred and mixed for 30 minutes to obtain a mixed suspension;

[0053] (3) adding the modified cellulose treated in step (1) to the mixed suspension obtained in step (2), stirring and mixing, adding the mixture to a film blowing machine, blowing the film, and then using a bag making machine to obtain the degradable water-soluble packaging bag.

[0054] Comparative Example 1:

[0055] Compared with Example 1, cellulose is treated by other modification methods to improve its degradability and solubility, such as esterification modification, and the rest of the process remains consistent with Example 1 of the present application.

[0056] Comparative Example 2:

[0057] Compared with Example 1, the temperature for pyrolyzing cellulose is 500-600° C., and the rest of the process is consistent with Example 1 of the present application.

[0058] Comparative Example 3:

[0059] Compared with Example 1, the temperature of the first heat treatment of cellulose remains unchanged, the temperature of the second heat treatment is 400-500° C., and the rest of the process remains consistent with Example 1 of the present application.

[0060] Comparative Example 4:

[0061] Compared with Example 1, phosphatidylserine is not added, and the cellulose is not modified, and the rest of the process is consistent with Example 1 of the present application.

[0062] Comparative Example 5:

[0063] Compared with Example 1, citric acid and starch are used to replace the phosphatidylserine in this solution, and the rest of the process is consistent with Example 1 of the present application.

[0064] Experimental example:

[0065] 1. Degradation experiment

[0066] The products obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were cut into a size of 20×20 cm and buried in soil. The biodegradation rates were tested after two weeks. The results are shown in Table 1.

[0067] Table 1 Biodegradation rate

[0068]

[0069] 2. Mechanical properties test

[0070] The products obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were cut into a size of 10×10 cm, and their tensile strength and elongation at break were tested. The results are shown in Table 2.

[0071] Table 2 Tensile strength and elongation at break

[0072]

[0073] According to the test results in Table 1 and Table 2, it can be seen that the biodegradability, tensile strength and elongation at break of the packaging bag prepared by the technical solution of the present invention are significantly better than those of Comparative Examples 1 to 5, indicating that it has excellent stability at room temperature, fast degradation speed, and no pollution to the environment. It also has excellent comprehensive mechanical properties and can meet the requirements of plastic products such as garbage bags and packaging bags.

[0074] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A degradable water-soluble packaging bag, characterized in that: The invention comprises the following raw material components in parts by weight: 20-30 parts of polylactic acid, 10-20 parts of phosphatidylserine, 10-15 parts of modified cellulose, 1-5 parts of solubilizer and 1-5 parts of plasticizer.

2. The degradable water-soluble packaging bag according to claim 1, characterized in that: The invention comprises the following raw material components in parts by weight: 25-30 parts of polylactic acid, 15-20 parts of phosphatidylserine, 10-15 parts of modified cellulose, 1-5 parts of solubilizer and 1-3 parts of plasticizer.

3. The degradable water-soluble packaging bag according to claim 1 or 2, characterized in that: The invention comprises the following raw material components in parts by weight: 30 parts of polylactic acid, 15 parts of phosphatidylserine, 15 parts of modified cellulose, 2 parts of solubilizer and 3 parts of plasticizer.

4. The degradable water-soluble packaging bag according to claim 3, characterized in that: The cellulose is modified by pyrolysis to obtain modified cellulose. The specific process is as follows: The cellulose is crushed into a particle size of 80-120 meshes, then heat-treated at 100-150°C for 30-50 minutes, and then heated to 200-250°C for further heat treatment for 20-30 minutes to obtain modified cellulose.

5. The degradable water-soluble packaging bag according to claim 4, characterized in that: The first heat treatment temperature is 120-150°C, and the second heat treatment temperature is 200-220°C.

6. The degradable water-soluble packaging bag according to claim 4, characterized in that: The first heat treatment time was 42 min, and the second heat treatment time was 25 min.

7. The degradable water-soluble packaging bag according to claim 3, characterized in that: The plasticizer is glycerol.

8. The degradable water-soluble packaging bag according to claim 3, characterized in that: The solubilizing agent is sodium salicylate.

9. A method for preparing the degradable water-soluble packaging bag according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) drying and sterilizing the modified cellulose for later use; (2) After mixing polylactic acid, phosphatidylserine, a solubilizer and a plasticizer, water is added and stirred evenly, and the mixture is heated to 50 to 60° C. and stirred and mixed for 20 to 30 minutes to obtain a mixed suspension; (3) adding the modified cellulose treated in step (1) to the mixed suspension obtained in step (2), stirring and mixing, and then forming a film and making a bag to obtain the degradable water-soluble packaging bag.

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