CN-121991409-A - Fully-biodegradable biaxially oriented heat-shrinkable film modified by bio-based compatilizer and preparation method thereof

Abstract

The invention discloses a bio-based compatilizer modified full-biodegradable biaxially oriented heat shrinkage film and a preparation method thereof, and relates to the technical field of degradable materials. The invention takes polylactic acid as a matrix and flexible biodegradable polyester as a modified component, introduces a bio-based compatilizer EGLA-ISB with a rigid isosorbide skeleton and an epoxy group, and prepares the target membrane material through melt blending, hot pressing to form a membrane and equal-multiplying power biaxial stretching. The EGLA-ISB double structure realizes triple synergistic effects of interfacial compatibilization, mechanical support and crystallization induction, remarkably enhances the bonding strength of two-phase interfaces, enables the film material to be continuously biaxially stretched at 2-3 times of high multiplying power in the longitudinal and transverse directions without rupture of the film, and widens the processing window. The obtained film material has high elongation at break, moderate heat shrinkage and good light transmittance, is totally bio-based, can be completely degraded, meets the green environment-friendly requirement, and has good industrialized application prospect in the packaging field.

Inventors

• ZHANG CAILI
• WENG YUNXUAN
• ZHAN CHANG

Assignees

• 北京工商大学

Dates

Publication Date

20260508

Application Date

20260310

Claims (10)

1. 1. The application of epoxy linoleate isosorbide as a compatilizer in preparing polylactic acid based full-biodegradation biaxially oriented heat shrinkage film.
2. 2. A fully biodegradable biaxially oriented heat-shrinkable film modified by a bio-based compatilizer is characterized in that the raw materials comprise polylactic acid, flexible biodegradable polyester and epoxy linoleate isosorbide; The flexible biodegradable polyester comprises one or more of polycaprolactone, polybutylene adipate-terephthalate, polybutylene succinate, and poly 3-hydroxybutyrate-4-hydroxybutyrate.
3. 3. The bio-based compatilizer modified full-biodegradable biaxially oriented heat shrinkage film according to claim 2, wherein the mass ratio of polylactic acid to flexible biodegradable polyester is 5:5-8:2, and the addition amount of the epoxy linoleate isosorbide is 1-2% of the total mass of the polylactic acid and the flexible biodegradable polyester.
4. 4. The preparation method of the bio-based compatilizer modified full-biodegradable biaxially oriented heat shrinkage film is characterized by comprising the following steps of: (1) Melt blending, namely melt blending the polylactic acid, the flexible biodegradable polyester and the epoxy linoleic acid isosorbide to obtain a modified mixture; (2) Hot-pressing to form a film, namely hot-pressing and forming the modified mixture, and cooling to obtain a basic film; (3) And (3) biaxially stretching, namely transversely and longitudinally biaxially stretching the base film to obtain the bio-based compatilizer modified full-biodegradable biaxially stretched heat-shrinkable film.
5. 5. The method of claim 4, wherein the flexible biodegradable polyester comprises one or more of polycaprolactone, polybutylene adipate-terephthalate, polybutylene succinate, and poly 3-hydroxybutyrate-4-hydroxybutyrate.
6. 6. The preparation method of the flexible biodegradable polyester, according to claim 4, is characterized in that the mass ratio of the polylactic acid to the flexible biodegradable polyester is 5:5-8:2, and the addition amount of the epoxy linolenate isosorbide is 1-2% of the total mass of the polylactic acid and the flexible biodegradable polyester.
7. 7. The preparation method of the alloy material according to claim 4, wherein the temperature of the melt blending is 170-190 ℃, the time is 4-5 minutes, the temperature of the hot press forming is 180-200 ℃, and the temperature of the biaxial stretching is 60-80 ℃.
8. 8. The method according to claim 4, wherein the stretching magnification in the transverse direction and the stretching magnification in the longitudinal direction are each 2 to 3 times.
9. 9. The method of claim 8, wherein the stretching is performed in both longitudinal and transverse directions.
10. 10. Use of the bio-based compatibilizer modified fully biodegradable biaxially oriented heat shrink film of any one of claims 2-3 in the field of food, commodity or electronic product packaging.

Description

Fully-biodegradable biaxially oriented heat-shrinkable film modified by bio-based compatilizer and preparation method thereof Technical Field The invention relates to the technical field of degradable materials, in particular to a fully-biodegradable biaxially oriented heat-shrinkable film modified by a bio-based compatilizer and a preparation method thereof. Background Polylactic acid (PLA) is taken as a biodegradable polymer material derived from a biological base, has the excellent characteristics of no toxicity, compostability, high transparency and high modulus, is an ideal choice for replacing the traditional petroleum-based heat shrink film and conforming to the development trend of green packaging, and has wide application prospect in the packaging fields of foods, daily necessities, electronic products and the like. But is limited by the rigid structure of the molecular chain, pure PLA has the inherent defects of obvious brittleness, low elongation at break and poor melt strength, is difficult to adapt to the severe processing technology of biaxial stretching, especially 2-3 times high-magnification continuous biaxial stretching, and the prepared film is easy to have the problems of stretching rupture, insufficient toughness and the like, and the technical bottleneck severely limits the commercialized popularization and application of the film in the field of heat shrinkage films. In order to improve the brittleness defect of PLA, the prior art usually adopts a blending modification mode, and the PLA is compounded with flexible biodegradable polyesters such as Polycaprolactone (PCL), polybutylene adipate-terephthalate (PBAT), polybutylene succinate (PBS) and the like, so that the toughness defect of the PLA is compensated by utilizing the characteristics of the flexible polyesters. However, there is a problem of thermodynamic incompatibility between PLA and the flexible biodegradable polyester, the bonding force of two phases is weak, the phenomena of interface debonding and stress concentration are very easy to occur in the biaxial stretching process, high-magnification continuous stretching film forming cannot be realized, even if low-magnification stretching can be completed, the obtained film can also greatly reduce the comprehensive performance due to interface defects, and the practical use requirement of the heat-shrinkable film is difficult to meet. In order to solve the problem of interfacial compatibility of PLA and flexible polyester, petroleum-based epoxy compatilizer (such as ADR series) is mostly adopted for interfacial modification in the prior art, but the compatilizer has no biodegradation characteristic, is contrary to the green environment-friendly property of PLA system, cannot realize full biodegradation of the heat shrinkage film after being added, and breaks through the original purpose of application of the bio-based material, and has the inherent defects of insufficient mechanical support, incapability of realizing high-rate biaxial stretching and poor light transmittance of the film, even if the low-rate stretching can be realized, the obtained film has limited interfacial modification effect, uneven mechanical property, poor heat shrinkage stability and the like, and is difficult to meet the practical application requirements of the heat shrinkage film. The series of defects not only limit the technical development and industry landing of the full-biodegradable heat-shrinkable film, but also lead the industry to be in the technical dilemma that the compatibilization effect and the environmental protection property cannot be considered, and the modification performance and the processing requirement are difficult to match. In summary, there is a need in the industry to provide a novel compatible modification scheme capable of effectively improving the interfacial compatibility of PLA/flexible biodegradable polyester, realizing 2-3 times of high-rate biaxial stretching processing, and completely meeting the full-biodegradation requirements, so as to break through the preparation bottleneck of the existing PLA-based heat-shrinkable film and promote the large-scale application of the degradable heat-shrinkable film in the packaging field. Disclosure of Invention The invention aims to provide a bio-based compatilizer modified full-biodegradable biaxially oriented heat shrink film and a preparation method thereof, so as to solve the problems in the prior art. In order to achieve the above object, the present invention provides the following solutions: The invention provides an application of epoxy linoleate isosorbide (EGLA-ISB) as a compatilizer in preparing polylactic acid based full-biodegradation biaxially oriented heat shrinkage film. The second technical proposal of the invention provides a fully biodegradable biaxially oriented heat-shrinkable film modified by a bio-based compatilizer, which comprises polylactic acid, flexible biodegradable polyester and epoxy linoleate