Degradable modified plastic as well as preparation method and application thereof

Abstract

The invention discloses degradable modified plastic as well as a preparation method and application thereof, and belongs to the technical field of degradable plastic. The degradable modified plastic is prepared from the following raw materials: polylactic acid, poly (butylene succinate), epoxidized soybean oil, polyvinyl alcohol, glycerol monolaurate, ethylenediaminetetraacetic acid, a release agent and filler, wherein the filler is bamboo powder loaded with iron ions. By regulating and controlling the types and proportions of the raw materials for preparing the plastic, the plastic with excellent degradation performance and mechanical performance can be obtained, the shopping bag is prepared from the plastic, the loading capacity can be remarkably improved, the plastic is easily degraded by microorganisms in the environment after being discarded, and environmental pollution is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable plastics, and in particular relates to a degradable modified plastic and a preparation method and application thereof. Background Art

[0002] Shopping bags provide great convenience to people in daily life and are essential items for people to go shopping. Among shopping bags, plastic shopping bags are the most widely used in China, which has caused serious pollution to the ecological environment. The development and application of degradable plastics is one of the most effective ways to solve this problem. Although degradable films have been used in the prior art, the strength of existing degradable shopping bags needs to be improved, so their load weight is limited. Summary of the invention

[0003] In view of the above-mentioned prior art, the present invention provides a degradable modified plastic and a preparation method and application thereof, so as to solve the technical problems that the existing plastic shopping bags cannot be degraded and have limited load-bearing capacity.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is to provide a degradable modified plastic, and the raw materials for preparing the plastic include the following components in parts by weight:

[0005] 30-40 parts of polylactic acid, 15-25 parts of polybutylene succinate, 5-10 parts of epoxidized soybean oil, 5-15 parts of polyvinyl alcohol, 1-3 parts of lauric acid monoglyceride, 3-6 parts of ethylenediaminetetraacetic acid, 0.3-1 parts of release agent and 3-6 parts of filler; the filler is prepared by the following steps:

[0006] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion;

[0007] S2: dissolving iron salt in deionized water, then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, then heating to 60-70°C, keeping the temperature and stirring for 30-60 minutes to obtain a precursor;

[0008] S3: Aging the precursor at room temperature for 30 to 60 minutes, and then filtering, washing, and drying to obtain the product.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Further, the raw material for preparation includes the following components in parts by weight:

[0011] 35 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxy soybean oil, 10 parts of polyvinyl alcohol, 2 parts of lauric acid monoglyceride, 5 parts of ethylenediaminetetraacetic acid, 0.5 parts of release agent and 4 parts of filler.

[0012] Furthermore, the release agent is montan wax.

[0013] Furthermore, the iron salt is ferric chloride, ferric nitrate or ferric sulfate.

[0014] Furthermore, the mass ratio of the iron salt to the bamboo powder is 1:20-30.

[0015] Furthermore, the final temperature of the heating in S2 is 65°C, and the stirring time is 45 minutes; and the aging time in S3 is 45 minutes.

[0016] The beneficial effect of the above technical solution of the present invention is that the degradable modified plastic in the present invention uses polylactic acid, polybutylene succinate, epoxy soybean oil and polyvinyl alcohol as main raw materials, and these raw materials have good biodegradability, so that the plastic finally prepared can be effectively degraded in the environment, and the environmental pollution problem caused by the use of plastics can be effectively avoided. In addition to the above components, the raw materials for preparing the plastic in the present invention also include lauric acid monoglyceride and ethylenediaminetetraacetic acid; wherein, lauric acid monoglyceride has good emulsifying properties, which can effectively improve the dispersibility and compatibility between the components in the plastic, thereby giving the plastic excellent mechanical properties; and adding a specific amount of lauric acid monoglyceride can improve the surface properties of the plastic, making it easier for microorganisms to attach and corrode the plastic, thereby promoting its degradation in the environment; in addition, lauric acid monoglyceride has excellent low temperature performance and toughness, and after being added to the plastic, it can work together with the filler to improve the toughness of the plastic, so that the plastic can better resist deformation and cracking when subjected to external forces. Ethylenediaminetetraacetic acid (EDTA) can chelate with the iron ions in the filler, which helps to promote the utilization of the iron ions in the filler, and the iron ions can not only be used as a catalyst for redox reactions to promote the degradation and decomposition of plastics, but also promote the activity of bacterial enzymes, thereby accelerating the decomposition of plastics by microorganisms. The raw materials for preparing the plastics in the present invention also include fillers, and the fillers used are made of bamboo powder. On the one hand, bamboo powder, as a carrier of iron ions, can make iron ions stably exist in plastics, which is conducive to the long-term promotion of plastic degradation. On the other hand, bamboo powder has good compatibility and processing performance. When it is mixed with plastics, it can be evenly dispersed in the plastic matrix, thereby enhancing the overall mechanical properties of the plastics; and, the iron ions loaded on the bamboo powder can chelate with the ethylenediaminetetraacetic acid in the plastics, and the three together form a special structure inside the plastics, thereby effectively improving the mechanical properties of the plastics.

[0017] The present invention also discloses a method for preparing the above-mentioned degradable modified plastic, comprising the following steps:

[0018] (1) mixing the raw material components in the formula amount, and then putting the mixture into an internal mixer for internal kneading to obtain a base material;

[0019] (2) The base material is placed in a screw extruder, and extruded and formed by the screw extruder to obtain a product.

[0020] Furthermore, in step (1), the banburying temperature is 150-170° C., and the banburying time is 30-45 min.

[0021] Furthermore, in step (2), the screw extruder is provided with a first melting section with a temperature of 135-145°C, a second melting section with a temperature of 150-160°C and a third melting section with a temperature of 120-130°C from the feed end to the discharge end, the screw speed is 110 rpm, and the extrusion port temperature is 125°C.

[0022] The invention also discloses the application of the above-mentioned degradable modified plastic, specifically, using the degradable modified plastic to prepare plastic shopping bags.

[0023] The beneficial effects of the present invention are as follows: by regulating the types and proportions of plastic preparation raw materials, the present invention can obtain a plastic with excellent degradation performance and mechanical properties. When the plastic is made into a shopping bag, the load-bearing capacity can be significantly improved, and the plastic can be easily degraded by microorganisms in the environment after being discarded, without causing environmental pollution. DETAILED DESCRIPTION

[0024] The polylactic acid used in the embodiments of the present invention was purchased from Nanjing Shengqinghe Chemical Co., Ltd.; polybutylene succinate was purchased from Wuhan Haishan Technology Co., Ltd.; epoxidized soybean oil was purchased from Shandong Qiangsen Chemical Co., Ltd.; polyvinyl alcohol (BP17) was purchased from Dongguan Yingxiang Plastic Raw Materials Co., Ltd.; and monolaurin was purchased from Guangzhou Tianjia Biotechnology Co., Ltd.

[0025] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0026] Example 1

[0027] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0028] 35 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxidized soybean oil, 10 parts of polyvinyl alcohol (BP 17), 2 parts of lauric acid monoglyceride, 5 parts of ethylenediaminetetraacetic acid, 0.5 parts of montan wax and 4 parts of filler; wherein the filler is prepared by the following steps:

[0029] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; the material-liquid ratio of bamboo powder to water is 1g:5mL;

[0030] S2: dissolving ferric chloride in deionized water to obtain an iron salt solution with a concentration of 0.5 g / mL; then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, heating the mixture to 65°C, and stirring the mixture for 45 minutes to obtain a precursor; after the iron salt solution is dropped into the bamboo powder dispersion, the mass ratio of iron salt to bamboo powder in the system is 1:25;

[0031] S3: Aging the precursor at room temperature for 45 minutes, then filtering, washing and drying to obtain the product.

[0032] The degradable modified plastic in this embodiment is prepared by the following steps:

[0033] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 160° C. for 45 minutes to obtain a base material;

[0034] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section at a temperature of 140° C., a second melting section at a temperature of 155° C., and a third melting section at a temperature of 125° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0035] Example 2

[0036] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0037] 30 parts of polylactic acid, 25 parts of polybutylene succinate, 5 parts of epoxidized soybean oil, 15 parts of polyvinyl alcohol (BP 17), 1 part of lauric acid monoglyceride, 6 parts of ethylenediaminetetraacetic acid, 0.3 parts of montan wax and 6 parts of filler; wherein the filler is prepared by the following steps:

[0038] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; the material-liquid ratio of bamboo powder to water is 1g:5mL;

[0039] S2: dissolving ferric sulfate in deionized water to obtain an iron salt solution with a concentration of 0.5 g / mL; then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, heating the mixture to 60°C, and stirring the mixture for 60 minutes to obtain a precursor; after the iron salt solution is dropped into the bamboo powder dispersion, the mass ratio of the iron salt to the bamboo powder in the system is 1:20;

[0040] S3: Aging the precursor at room temperature for 30 minutes, then filtering, washing and drying to obtain the product.

[0041] The degradable modified plastic in this embodiment is prepared by the following steps:

[0042] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 150° C. for 45 minutes to obtain a base material;

[0043] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section with a temperature of 135° C., a second melting section with a temperature of 150° C., and a third melting section with a temperature of 120° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0044] Example 3

[0045] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0046] 40 parts of polylactic acid, 15 parts of polybutylene succinate, 10 parts of epoxidized soybean oil, 5 parts of polyvinyl alcohol (BP 17), 3 parts of lauric acid monoglyceride, 3 parts of ethylenediaminetetraacetic acid, 1 part of montan wax and 3 parts of filler; wherein the filler is prepared by the following steps:

[0047] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; the material-liquid ratio of bamboo powder to water is 1g:5mL;

[0048] S2: dissolving ferric nitrate in deionized water to obtain an iron salt solution with a concentration of 0.5 g / mL; then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, heating the mixture to 70°C, and stirring the mixture for 30 minutes to obtain a precursor; after the iron salt solution is dropped into the bamboo powder dispersion, the mass ratio of iron salt to bamboo powder in the system is 1:30;

[0049] S3: Aging the precursor at room temperature for 60 minutes, then filtering, washing and drying to obtain the product.

[0050] The degradable modified plastic in this embodiment is prepared by the following steps:

[0051] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 170° C. for 30 minutes to obtain a base material;

[0052] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section with a temperature of 145° C., a second melting section with a temperature of 160° C., and a third melting section with a temperature of 130° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0053] Comparative Example 1

[0054] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0055] 37 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxidized soybean oil, 10 parts of polyvinyl alcohol (BP 17), 5 parts of ethylenediaminetetraacetic acid, 0.5 parts of montan wax and 4 parts of filler; wherein the filler is prepared by the following steps:

[0056] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; the material-liquid ratio of bamboo powder to water is 1g:5mL;

[0057] S2: dissolving ferric chloride in deionized water to obtain an iron salt solution with a concentration of 0.5 g / mL; then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, heating the mixture to 65°C, and stirring the mixture for 45 minutes to obtain a precursor; after the iron salt solution is dropped into the bamboo powder dispersion, the mass ratio of iron salt to bamboo powder in the system is 1:25;

[0058] S3: Aging the precursor at room temperature for 45 minutes, then filtering, washing and drying to obtain the product.

[0059] The degradable modified plastic in this comparative example is prepared by the following steps:

[0060] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 160° C. for 45 minutes to obtain a base material;

[0061] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section at a temperature of 140° C., a second melting section at a temperature of 155° C., and a third melting section at a temperature of 125° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0062] Comparative Example 2

[0063] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0064] 40 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxidized soybean oil, 10 parts of polyvinyl alcohol (BP 17), 2 parts of lauric acid monoglyceride, 0.5 parts of montan wax and 4 parts of filler; wherein the filler is prepared by the following steps:

[0065] S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; the material-liquid ratio of bamboo powder to water is 1g:5mL;

[0066] S2: dissolving ferric chloride in deionized water to obtain an iron salt solution with a concentration of 0.5 g / mL; then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, heating the mixture to 65°C, and stirring the mixture for 45 minutes to obtain a precursor; after the iron salt solution is dropped into the bamboo powder dispersion, the mass ratio of iron salt to bamboo powder in the system is 1:25;

[0067] S3: Aging the precursor at room temperature for 45 minutes, then filtering, washing and drying to obtain the product.

[0068] The degradable modified plastic in this comparative example is prepared by the following steps:

[0069] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 160° C. for 45 minutes to obtain a base material;

[0070] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section at a temperature of 140° C., a second melting section at a temperature of 155° C., and a third melting section at a temperature of 125° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0071] Comparative Example 3

[0072] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0073] 35 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxidized soybean oil, 10 parts of polyvinyl alcohol (BP 17), 2 parts of lauric acid monoglyceride, 5 parts of ethylenediaminetetraacetic acid, 0.5 parts of montan wax and 4 parts of filler; wherein the filler is bamboo powder.

[0074] The degradable modified plastic in this comparative example is prepared by the following steps:

[0075] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 160° C. for 45 minutes to obtain a base material;

[0076] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section at a temperature of 140° C., a second melting section at a temperature of 155° C., and a third melting section at a temperature of 125° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0077] Comparative Example 4

[0078] A degradable modified plastic, the preparation raw materials include the following components in parts by weight:

[0079] 40 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxidized soybean oil, 10 parts of polyvinyl alcohol (BP 17), 2 parts of lauric acid monoglyceride, 0.5 parts of montan wax and 4 parts of filler; wherein the filler is bamboo powder.

[0080] The degradable modified plastic in this comparative example is prepared by the following steps:

[0081] (1) Mixing the raw material components in the formula amount, then placing the mixture in an internal mixer, and mixing at a temperature of 160° C. for 45 minutes to obtain a base material;

[0082] (2) The base material after internal mixing is immediately transferred to a screw extruder. The screw extruder is provided with a first melting section at a temperature of 140° C., a second melting section at a temperature of 155° C., and a third melting section at a temperature of 125° C. from the feed end to the discharge end. The screw speed is 110 rpm, and the extrusion port temperature is 125° C. The base material is extruded and formed by the screw extruder to obtain the product.

[0083] Experimental example

[0084] The degradable modified plastics in the above embodiments and comparative examples were used as raw materials, and plastic shopping bags were made by using a conventional shopping bag preparation process; then the biodegradability of the plastic shopping bags was tested by using the test process in ISO 16929 (2013), and the puncture performance of the plastic shopping bags was tested by using the test process in ASTM D5748-95 (2001). The results are listed in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] As can be seen from Table 1, the plastics prepared by the technical solutions (Examples 1 to 3) of the present invention have excellent biodegradability and puncture resistance, which can not only improve the load-bearing capacity of plastic bags, but also can be quickly degraded in the wild without causing pollution to the environment.

[0089] Compared with Example 1, the preparation raw material of Comparative Example 1 lacks monolaurin, resulting in poor dispersion between components, thereby destroying the mechanical properties of the plastic; and having an adverse effect on the surface properties of the plastic, thereby affecting the attachment of microorganisms and further affecting the biodegradability of the plastic.

[0090] Compared with Example 1, in Comparative Example 2, the raw materials for preparation lack ethylenediaminetetraacetic acid, which results in that the iron ions in the filler cannot be well fixed, and at the same time affects the internal structure of the plastic, resulting in poor biodegradability and mechanical properties of the obtained plastic.

[0091] Compared with Example 1, in Comparative Example 3, the filler is not loaded with iron ions, resulting in that the plastic cannot be well catalytically degraded, thereby affecting the biodegradability of the plastic.

[0092] Compared with Example 1, in Comparative Example 4, ethylenediaminetetraacetic acid is lacking in the raw materials for preparation, and the filler used is not loaded with iron ions. Not only is the internal structure of the obtained plastic incomplete, resulting in poor mechanical properties of the plastic, but also the lack of iron catalysis causes the plastic's biodegradability to deteriorate.

[0093] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A degradable modified plastic, characterized in that: The raw materials for preparation include the following components in parts by weight: 30-40 parts of polylactic acid, 15-25 parts of polybutylene succinate, 5-10 parts of epoxidized soybean oil, 5-15 parts of polyvinyl alcohol, 1-3 parts of lauric acid monoglyceride, 3-6 parts of ethylenediaminetetraacetic acid, 0.3-1 parts of release agent and 3-6 parts of filler; the filler is prepared by the following steps: S1: dispersing bamboo powder in water to obtain bamboo powder dispersion; S2: dissolving iron salt in deionized water, then dropping the iron salt solution into the bamboo powder dispersion under stirring conditions, then heating to 60-70°C, keeping the temperature and stirring for 30-60 minutes to obtain a precursor; S3: Aging the precursor at room temperature for 30 to 60 minutes, and then filtering, washing, and drying to obtain the product.

2. The degradable modified plastic according to claim 1, characterized in that: The raw materials for preparation include the following components in parts by weight: 35 parts of polylactic acid, 20 parts of polybutylene succinate, 8 parts of epoxy soybean oil, 10 parts of polyvinyl alcohol, 2 parts of lauric acid monoglyceride, 5 parts of ethylenediaminetetraacetic acid, 0.5 parts of release agent and 4 parts of filler.

3. The degradable modified plastic according to claim 1 or 2, characterized in that: The release agent is montan wax.

4. The degradable modified plastic according to claim 1, characterized in that: The iron salt is ferric chloride, ferric nitrate or ferric sulfate.

5. The degradable modified plastic according to claim 4, characterized in that: The mass ratio of the iron salt to the bamboo powder is 1:20-30.

6. The degradable modified plastic according to claim 1, characterized in that: The final temperature in S2 is 65°C and the stirring time is 45 minutes; the aging time in S3 is 45 minutes.

7. The method for preparing the degradable modified plastic according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing the raw material components in the formula amount, and then putting the mixture into an internal mixer for internal kneading to obtain a base material; (2) The base material is placed in a screw extruder, and extruded and formed by the screw extruder to obtain a product.

8. The preparation method according to claim 7, characterized in that: In step (1), the banburying temperature is 150-170° C. and the banburying time is 30-45 min.

9. The preparation method according to claim 7, characterized in that: In step (2), the screw extruder is provided with a first melting section with a temperature of 135-145°C, a second melting section with a temperature of 150-160°C and a third melting section with a temperature of 120-130°C from the feed end to the discharge end, the screw speed is 110 rpm, and the extrusion port temperature is 125°C.

10. The use of the degradable modified plastic according to any one of claims 1 to 6, characterized in that: Degradable modified plastics are used to prepare plastic shopping bags.

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