Bio-based degradable high-strength polyethylene film and preparation method thereof

Abstract

The invention relates to the technical field of polyethylene films, and particularly discloses a bio-based degradable high-strength polyethylene film and a preparation method thereof. The bio-based degradable high-strength polyethylene film is prepared from the following raw materials: PE resin, a bio-based degradable material, a slipping agent and a rheological agent, the bio-based degradable material is formed by blending a polylactic acid stereocomplex and nano cellulose. The maximum 14C of the polyethylene film is up to 25%, the light transmittance is up to 92%, the transparency and the degradability of the polyethylene film are improved, the maximum transverse tensile strength, the maximum longitudinal tensile strength and the maximum transverse yield strength are 27 N, 31.2 N and 9.5 MPa respectively, and the polyethylene film has high strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyethylene film, more particularly, it relates to a biobased degradable high-strength polyethylene film and a preparation method. BACKGROUND

[0002] Polyethylene film is a thin and flexible plastic film made of polyethylene resin through processes such as blowing, casting or calendering, and is the largest and most widely used plastic film type in the world. It is widely used in outdoor plastic products such as umbrellas, plastic awnings and sunshields. Due to the large amount of use, producing biobased degradable polyethylene film is a key technology to combat "white pollution", protect the ecological environment and promote sustainable development, so as to reduce the white pollution of outdoor plastic products to the environment.

[0003] In related technologies, polybutylene terephthalate is added to polyethylene resin to achieve degradable effect, but the polyethylene film prepared has high haze and poor transparency, which is difficult to meet the actual use requirements of transparent umbrellas or plastic awnings and other outdoor plastic products, and the strength of the polyethylene film is required to be high in repeated opening and closing of the umbrella.

[0004] Therefore, it is necessary to develop a high-strength polyethylene film with high transparency and biodegradability to meet the actual use requirements. SUMMARY

[0005] In order to improve the transparency of the polyethylene film and the degradability of the polyethylene film, the present application provides a biobased degradable high-strength polyethylene film and a preparation method.

[0006] In the first aspect, the present application provides a biobased degradable high-strength polyethylene film, which adopts the following technical scheme: a biobased degradable high-strength polyethylene film includes the following raw materials by weight: PE resin 75-90 parts, biobased degradable material 10-25 parts, slip agent 0.1-0.3 parts, rheological agent 0.5-1 part; the biobased degradable material is a blend of poly lactic acid stereocomplex and nanocellulose.

[0007] By adopting the above scheme, the biobased degradable material is added in the polyethylene film raw material, so that the polyethylene film achieves the degradable effect, and the polylactic acid stereocomplex in the biobased degradable material is a completely degradable biobased material, which can be gradually decomposed into carbon dioxide and water in the compost, soil or water environment through hydrolysis and microbial action, when the polylactic acid stereocomplex is added in the polyethylene resin, the polylactic acid stereocomplex is gradually broken in the degradation process to form a porous structure, increase the contact area of the PE resin with the microorganisms and moisture in the environment, and indirectly promote the oxidative degradation of the PE resin, so that the polyethylene film has the degradable function; the nanocellulose not only can completely degrade to further improve the degradability of the PE resin, has high compatibility with the polylactic acid stereocomplex, and can also improve the strength and durability of the polyethylene film, in addition, the addition of the nanocellulose will not reduce the transparency of the polylactic acid stereocomplex, and the transparency of the polyethylene film can be maintained. The biobased degradable material is formed by blending the polylactic acid stereocomplex and the nanocellulose, and the two have a composite effect, the nanocellulose can be combined with the polylactic acid stereocomplex through hydrogen bonds to form a three-dimensional network structure, inhibit the generation of large-size crystals, and at the same time, its high hydrophilicity promotes hydrolytic degradation, further improves the degradation rate of the polylactic acid stereocomplex, and thus improves the degradation effect of the polyethylene film.

[0008] As preferred: the biobased degradable high-strength polyethylene film includes the following raw materials by weight: PE resin 82-88 parts, biobased degradable material 15-20 parts, slip agent 0.15-0.25 parts, rheological agent 0.7-0.9 parts.

[0009] As preferred: the mass ratio of the nanocellulose to the polylactic acid stereocomplex is 1:(3-5).

[0010] By adopting the above scheme, the mass ratio of the nanocellulose to the polylactic acid stereocomplex is adjusted, so that the composite effect of the two can be further improved, and thus the degradability of the polyethylene film is improved.

[0011] As preferred: the polylactic acid stereocomplex is a modified polylactic acid stereocomplex, which is prepared by modifying a metallocene polyolefin elastomer, and specifically: S1, the polylactic acid stereocomplex is vacuum dried at 80℃ for 10-14h, and the metallocene polyolefin elastomer is vacuum dried at 60℃ for 5-7h; S2, the metallocene polyolefin elastomer is mixed with the polylactic acid stereocomplex, maleic anhydride grafted SEBS is added, extruded and granulated, and vacuum dried to obtain a modified polylactic acid.

[0012] By adopting the above scheme, the metallocene polyolefin elastomer is used to modify the polylactic acid stereocomplex, blending and extruding granulation, which can improve the strength of the polyethylene film, and the modified polylactic acid stereocomplex is more easily degraded by the environment, and the modified polylactic acid stereocomplex does not reduce the light transmittance of the polyethylene film.

[0013] As a preferred: the mass ratio of the metallocene polyolefin elastomer and the polylactic acid stereocomplex is 1:(3-5).

[0014] By adopting the above scheme, the mass ratio of the metallocene polyolefin elastomer and the polylactic acid stereocomplex is adjusted, which can further improve the modification effect of the polylactic acid stereocomplex, thereby improving the degradability of the polyethylene film.

[0015] As a preferred: the polyethylene film raw material further includes 3-5 parts by weight of polyethylene glycol and 1-3 parts by weight of 1-ethyl-3-methyl imidazole trifluoromethanesulfonate.

[0016] By adopting the above scheme, the addition of polyethylene glycol in the polyethylene film raw material can improve the uniformity of the bio-based degradable material in the PE resin, thereby improving the strength and degradability of the polyethylene film and ensuring the transparency. The addition of 1-ethyl-3-methyl imidazole trifluoromethanesulfonate can further improve the effect of polyethylene glycol, thereby further improving the strength and degradability of the polyethylene film.

[0017] As a preferred: the weight ratio of 1-ethyl-3-methyl imidazole trifluoromethanesulfonate and polyethylene glycol is 1:(2-4).

[0018] By adopting the above scheme, the weight ratio of polyethylene glycol and 1-ethyl-3-methyl imidazole trifluoromethanesulfonate is adjusted, which can further improve the strength and degradability of the polyethylene film.

[0019] In a second aspect, the application provides a preparation method of the bio-based degradable high-strength polyethylene film of any one of claims 1-7, which is specifically realized by the following technical scheme: A preparation method of the bio-based degradable high-strength polyethylene film of any one of claims 1-7, which includes the following operation steps: melting the raw materials of the polyethylene film and placing them in a double-screw extruder for extrusion, blowing in compressed air while pulling upward, cooling and shaping, and pulling and winding to obtain the bio-based degradable high-strength polyethylene film.

[0020] In summary, the application includes at least one of the following beneficial technical effects: 1. The application adds the polylactic acid stereocomplex and nanocellulose blended as a bio-based degradable material to the raw material of the polyethylene film, which can improve the degradability of the polyethylene film. 14C is 19%, and the light transmittance is 89.2-90.5%, which improves the transparency and degradability of the polyethylene film.

[0021] 2. The application modifies the polylactic acid stereocomplex in the biobased degradable material, and controls the mass ratio of the metallocene polyolefin elastomer to the polylactic acid stereocomplex in the modification process, so that the polyethylene film has 14 C is 20%, and the light transmittance is 91.1-91.5%, which further improves the transparency and degradability of the polyethylene film.

[0022] 3. The application adds polyethylene glycol and 1-ethyl-3-methyl imidazole trifluoromethanesulfonate to the raw material of the polyethylene film, so that the polyethylene film has 14 C is 23-25%, and the light transmittance is 91.8-92.0%, which further improves the transparency and degradability of the polyethylene film.

[0023] 4. The polyethylene film obtained by the application has the highest transverse tensile strength, longitudinal tensile strength, transverse yield strength and longitudinal yield strength of 27 N, 31.2 N and 9.5 MPa, respectively, and has high strength. DETAILED DESCRIPTION

[0024] The application will be further described in detail below in combination with specific examples. The following raw materials in the application are all commercially available products, and are disclosed to fully disclose the raw materials of the application, and should not be understood as limiting the source of the raw materials. Specifically, the PE resin is brand HDPE, grade 9455F; the slip agent is selected from oleic acid amide; the rheological agent is SC-PE200; the polylactic acid stereocomplex is purchased from Shenzhen Guanghua Weiye; the nanocellulose has an effective ingredient content of 99%, a length of 0.5-3 pm, and a width of 10-50 nm; the metallocene polyolefin elastomer is purchased from ExxonMobil Chemical Company; the maleic anhydride grafted SEBS is brand Korten, type 1901GT; the polyethylene glycol has an effective ingredient content of 99%; and the 1-ethyl-3-methyl imidazole trifluoromethanesulfonate has an effective ingredient content of 98%.

[0025] The following is a preparation example of the modified polylactic acid stereocomplex Preparation Example 1 The modified polylactic acid stereocomplex of Preparation Example 1 is specifically: S1, 1 kg of polylactic acid stereocomplex is vacuum dried at 80°C for 10-14 h, and 500 g of metallocene polyolefin elastomer is vacuum dried at 60°C for 5-7 h; S2, the metallocene polyolefin elastomer is mixed with the polylactic acid stereocomplex, 30 g of maleic anhydride grafted SEBS is added, extruded and granulated, and vacuum dried to obtain the modified polylactic acid.

[0026] Preparation Example 2-5 The modified polylactic acid stereocomplex of Preparation Example 2-5 is completely identical to the raw material types and preparation method of Preparation Example 1, except that the amount of the metallocene polyolefin elastomer is different, specifically 333 g, 250 g, 200 g and 167 g, and the remaining steps are the same as those of Preparation Example 1.

[0027] Example 1 The biobased degradable high-strength polyethylene film of Example 1 is prepared by the following operation steps: According to the amount in Table 1, the raw materials of the polyethylene film are melt-extruded in a twin-screw extruder, the length-diameter ratio of the twin-screw extruder is 44, the screw rotation speed is 80 rpm, the temperatures of the conveying section, the melting section, the mixing section, the exhaust section and the homogenizing section are 200℃, 210℃, 215℃, 220℃ and 210℃ respectively, the mother granules are prepared by blow molding, compressed air is blown in, the air pressure is 0.03-0.06 MPa, at the same time, the film is pulled up, the pulling speed is 50 m / min, the pulling temperature is 50℃, the film is cooled and shaped, and the film is collected by pulling, to obtain the biobased degradable high-strength polyethylene film.

[0028] Examples 2-5 The biobased degradable high-strength polyethylene film of Examples 2-5 is completely identical to the preparation method and raw material types of Example 1, except that the amounts of the raw materials are different, which are specifically shown in Table 1.

[0029] Table 1 Amounts of raw materials of polyethylene films of Examples 1-5 (unit: kg) Examples 6-10 The preparation method of the biobased degradable high-strength polyethylene film of Examples 6-10 is the same as that of Example 3, except that the modified polylactic acid stereocomplex in the biobased degradable material is selected from the modified polylactic acid stereocomplexes prepared in Preparation Examples 1-5, and the remaining raw material types and amounts are the same as those of Example 3.

[0030] Examples 11-15 The preparation method of the biobased degradable high-strength polyethylene film of Examples 11-15 is the same as that of Example 8, except that the polyethylene film raw materials further include polyethylene glycol and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, and the specific amounts are 3 kg and 3 kg, 2 kg and 4 kg, 1 kg and 3 kg, 1 kg and 4 kg, 1 kg and 5 kg, respectively, and the remaining raw material types and amounts are the same as those of Example 8.

[0031] Comparative Example 1 The preparation method of the biobased degradable high-strength polyethylene film of Comparative Example 1 is completely same as that of Example 1, except that the polylactic acid stereocomplex in the biobased degradable material is replaced by equal amount of levorotatory polylactic acid, and the rest of raw materials and blending amount are same as those of Example 1.

[0032] Comparative Example 2 The preparation method of the biobased degradable high-strength polyethylene film of Comparative Example 2 is completely same as that of Example 1, except that the polylactic acid stereocomplex in the biobased degradable material is replaced by equal amount of dextrorotatory polylactic acid, and the rest of raw materials and blending amount are same as those of Example 1.

[0033] Comparative Example 3 The preparation method of the biobased degradable high-strength polyethylene film of Comparative Example 3 is completely same as that of Example 1, except that the polylactic acid stereocomplex in the biobased degradable material is replaced by equal amount of nanocellulose, and the rest of raw materials and blending amount are same as those of Example 1.

[0034] Comparative Example 4 The preparation method of the biobased degradable high-strength polyethylene film of Comparative Example 4 is completely same as that of Example 1, except that the nanocellulose in the biobased degradable material is replaced by equal amount of polylactic acid stereocomplex, and the rest of raw materials and blending amount are same as those of Example 1.

[0035] Performance detection The polyethylene films obtained in different Examples 1-15 and Comparative Examples 1-4 are respectively detected for performance by using the following detection standards or methods, and the detection results are shown in Table 2.

[0036] Degradability: the polyethylene film after degradation is detected for the content of carbon by using the method of 14C accelerated mass spectrometry, specifically, the polyethylene film is soaked in toluene solution to remove the non-carbon components in the polyethylene film, filtered, and the number of ions is directly counted by using the accelerator mass spectrometry method, and the content of carbon is calculated by the ratio of C. 14C 14C 14C 12 14C

[0037] Transparency: the polyethylene film is placed for 7 days, and then the light transmittance of the film is tested by using a light transmittance tester according to GB2410-80.

[0038] Tensile force and yield strength: the transverse tensile strength, longitudinal tensile strength, transverse yield strength and longitudinal yield strength of the polyethylene film are respectively detected according to the standard of GB / T1040.3-2006. The sample size is 25mmx100mm, the clamping distance is 100mm, and the tensile speed is 500mm / min.

[0039] Table 2 Performance detection results of different polyethylene films​​​​​ The detection results of Table 2 show that the polyethylene film obtained by the application has 14 C is up to 25%, the light transmittance is up to 92%, the transparency and degradability of the polyethylene film are improved, and the transverse tensile force, longitudinal tensile force and transverse yield strength are up to 27N, 31.2N and 9.5MPa respectively, which have high strength.

[0040] Combining the performance detection data of the polyethylene films of Examples 1-5, it is found that the polyethylene films of Examples 2-4 have 14 C is 19%, the light transmittance is 89.2-90.5%, which is higher than that of Examples 1 and 5, indicating that the mass ratio of nanocellulose to polylactic acid stereocomplex in the biobased degradable material is 1:(3-5), which is more appropriate, and the transparency and degradability of the polyethylene film are improved.

[0041] Combining the performance detection data of the polyethylene films of Examples 6-10, it is found that the polyethylene films of Examples 7-9 have 14 C is 20%, the light transmittance is 91.1-91.5%, which is higher than that of Examples 6 and 10, indicating that the polylactic acid stereocomplex in the biobased degradable material is modified, and the mass ratio of metallocene polyolefin elastomer to polylactic acid stereocomplex in the modification process is controlled, which can further improve the transparency and degradability of the polyethylene film.

[0042] Combining the performance detection data of the polyethylene films of Examples 11-15, it is found that the polyethylene films of Examples 12-14 have 14 C is 23-25%, the light transmittance is 91.8-92.0%, which is higher than that of Examples 11 and 15, indicating that the addition of polyethylene glycol and 1-ethyl-3-methylimidazole trifluoromethanesulfonate in the polyethylene film raw material, and the control of the weight ratio of the two, can further improve the transparency and degradability of the polyethylene film.

[0043] Combining the performance detection data of the polyethylene films of Examples 1 and Comparative Examples 1-4, it is found that the blending of polylactic acid stereocomplex and nanocellulose as biobased degradable material into the polyethylene film raw material can improve the transparency and degradability of the polyethylene film to different degrees.

[0044] The specific embodiments are only an explanation of the application and are not a limitation of the application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as it is within the scope of the claims of the application, it is protected by the patent law.

Claims

1. A bio-based degradable high-strength polyethylene film, characterized in that: The raw materials include the following parts by weight: 75-90 parts of PE resin, 10-25 parts of biodegradable materials, 0.1-0.3 parts of lubricant, and 0.5-1 parts of rheological agent; The bio-based degradable material is formed by blending a polylactic acid stereocomplex and nanocellulose.

2. The bio-based degradable high-strength polyethylene film according to claim 1, characterized in that: The bio-based degradable high-strength polyethylene film comprises the following raw materials in parts by weight: 82-88 parts of PE resin, 15-20 parts of bio-based degradable material, 0.15-0.25 parts of lubricant, and 0.7-0.9 parts of rheological agent.

3. The bio-based degradable high-strength polyethylene film according to claim 1, characterized in that: The mass ratio of the nanocellulose to the polylactic acid stereocomplex is 1:(3-5).

4. The bio-based degradable high-strength polyethylene film according to claim 1, characterized in that: The polylactic acid stereocomplex is a modified polylactic acid stereocomplex, which is prepared by modifying a metallocene polyolefin elastomer, specifically: S1. Dry the polylactic acid stereocomplex at 80°C in vacuum for 10-14 hours, and dry the metallocene polyolefin elastomer at 60°C in vacuum for 5-7 hours; S2. Mixing the metallocene polyolefin elastomer with the polylactic acid stereocomplex, adding maleic anhydride grafted SEBS to blend, extruding into granules, and vacuum drying to obtain modified polylactic acid.

5. The bio-based degradable high-strength polyethylene film according to claim 4, characterized in that: The mass ratio of the metallocene polyolefin elastomer to the polylactic acid stereocomplex is 1:(3-5).

6. The bio-based degradable high-strength polyethylene film according to claim 1, characterized in that: The polyethylene film raw material further comprises 3-5 parts by weight of polyethylene glycol and 1-3 parts by weight of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate.

7. The bio-based degradable high-strength polyethylene film according to claim 6, characterized in that: The weight ratio of the 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to the polyethylene glycol is 1:(2-4).

8. A method for preparing the bio-based degradable high-strength polyethylene film according to any one of claims 1 to 7, characterized in that: The process comprises the following steps: melting the raw materials of the polyethylene film and extruding them through a twin-screw extruder, blowing compressed air into the extruder, pulling the film upward, cooling and shaping the film, and pulling and winding the film to obtain a bio-based degradable high-strength polyethylene film.

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