Double-drawing down-blowing type water drawing secondary expansion biodegradable heat shrinkage film production process and PBSEHL heat shrinkage film

Abstract

The invention belongs to the technical field of packaging materials, and discloses a double-drawing down-blowing type water drawing secondary expansion biodegradable heat shrinkage film production process and a PBSEHL heat shrinkage film, the production process comprises the following steps: weighing a PBSEHL master batch, and carrying out melt extrusion to obtain a composite material; carrying out first blowing on the composite material, and immediately carrying out first cooling to obtain a primary expanded film; drawing the primary expansion film to form a tubular film; carrying out heating and second blowing on the pipe film, and immediately carrying out second cooling to obtain a secondary expansion film; and performing two-way stretching and third cooling on the secondary expansion film in a wet environment, and then slitting to obtain the PBSEHL thermal shrinkage film. Wherein a method adopted by the first blowing and the second blowing comprises a downward blowing process; the relative humidity of the humid environment is 90%-95%. According to the production process provided by the invention, through downward blowing type secondary expansion and two-way stretching in a humid environment, molecular arrangement of the heat shrinkage film can be promoted, so that the transverse shrinkage capacity of the PBSEHL heat shrinkage film in the use process is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of packaging materials, and specifically relates to a production process for a double-pull down-blowing water-pull secondary-expanded biodegradable heat shrinkable film and a PBSEHL heat shrinkable film. Background Art

[0002] Polybutylene succinate (PBS) is an environmentally friendly plastic with good biodegradability. It can be decomposed into carbon dioxide and water by microorganisms in the natural environment. Compared with traditional plastics, it reduces the pollution of soil, water and air, and is more helpful to protect the ecological environment. Because PBS has high mechanical strength and hardness, while maintaining a certain degree of flexibility and wear resistance, and also has good insulation performance, chemical corrosion resistance and processing performance, it has been widely used in the manufacture of heat shrink film.

[0003] Enzymatic lignin (EHL) is a natural polymer compound obtained from wood biomass through an enzymatic hydrolysis process. It has certain biodegradability and renewability, good compatibility with PBS, and can effectively improve the mechanical properties of composite materials. The present application found in preliminary experiments that although the PBSEHL heat shrinkable film prepared by the existing process has good mechanical properties, it will shrink poorly in the lateral direction during use, affecting the wrapping ability of the product.

[0004] Therefore, a new heat shrinkable film production process is needed to overcome the technical defect of PBSEHL heat shrinkable film prepared by the existing process in the transverse negative shrinkage during use. Summary of the invention

[0005] The problem that the present application aims to solve is to provide a biodegradable heat shrinkable film production process and a PBSEHL heat shrinkable film with double-pull down-blowing water-pull secondary expansion. Through down-blowing secondary expansion and biaxial stretching in a humid environment, the molecular arrangement of the heat shrinkable film can be promoted, thereby improving the lateral shrinkage ability of the PBSEHL heat shrinkable film during use.

[0006] On the one hand, the present application provides a double-draw down-blowing water-drawn secondary-expanded biodegradable heat-shrinkable film production process, comprising the following steps:

[0007] The PBSEHL masterbatch is weighed and melt-extruded to obtain a composite material; the composite material is first inflated and then immediately cooled to obtain a primary expansion film; the primary expansion film is pulled to form a tubular film; the tubular film is heated and second inflated and then immediately cooled to obtain a secondary expansion film; and the secondary expansion film is biaxially stretched in a wet environment and thirdly cooled, and then cut to obtain the PBSEHL heat shrink film;

[0008] Wherein, the methods adopted by the first inflation and the second inflation include a down-blowing process;

[0009] The relative humidity of the humid environment is 90% to 95%.

[0010] Furthermore, the ingredients of the PBSEHL masterbatch include, by weight, 60 to 70 parts of polybutylene succinate (PBS), 15 to 25 parts of enzymatically hydrolyzed lignin (EHL), and 5 to 15 parts of filler masterbatch.

[0011] Furthermore, the filler masterbatch comprises, by weight, 4 to 6 parts of lubricant, 5 to 7 parts of chain extender, 0.1 to 0.5 parts of antioxidant, and 4 to 6 parts of anti-blocking agent.

[0012] Furthermore, the lubricant includes polylactic acid.

[0013] Furthermore, the chain extender includes hexamethylene diisocyanate.

[0014] Furthermore, the antioxidant includes antioxidant 1010.

[0015] Furthermore, the opening agent includes silicon dioxide powder.

[0016] Furthermore, the melt extrusion is completed in a twin-screw extruder, the aspect ratio of the twin-screw extruder is (30-40):1, the barrel temperature of the twin-screw extruder is 150-160°C in the first section, 155-165°C in the second section, 160-170°C in the third section, 165-175°C in the fourth section, 160-170°C in the fifth section, and 150-160°C in the sixth section, the rotation speed of the twin-screw extruder is 70-80r / min, and the lip die opening of the twin-screw extruder is 2.0-2.4mm.

[0017] Furthermore, the traction speed is 10-15 m / min.

[0018] Furthermore, the folded diameter of the tubular membrane is 450 to 500 mm.

[0019] Furthermore, the heating temperature is 90-100°C.

[0020] Furthermore, the temperature of the biaxial stretching is 85 to 95° C., the transverse stretching ratio of the biaxial stretching is 3 to 4 times, and the longitudinal stretching ratio of the biaxial stretching is 2 to 3 times.

[0021] Furthermore, the first cooling temperature is 4-8°C.

[0022] Furthermore, the second cooling temperature is 15-25°C.

[0023] Furthermore, the third cooling temperature is 4-8°C.

[0024] On the other hand, the present application provides a PBSEHL heat shrinkable film produced by the above-mentioned biodegradable heat shrinkable film production process.

[0025] This application has the following beneficial effects:

[0026] (1) The present application can perform more precise stretching and orientation on the PBSEHL masterbatch through secondary downward expansion, thereby improving the shrinkage rate of the PBSEHL heat shrinkable film.

[0027] (2) The present application performs biaxial stretching in a humid environment, which can optimize the arrangement of molecular chains and enable the polymer chains to form a more ordered structure during the biaxial stretching process, thereby improving the mechanical and optical properties of the PBSEHL heat shrinkable film. At the same time, the humid environment is conducive to the rearrangement and crystallization of the polymer chains, so that the PBSEHL heat shrinkable film can have better strength and heat resistance. In addition, biaxial stretching in a humid environment can also improve the gas barrier properties of the PBSEHL heat shrinkable film, promote the PBSEHL heat shrinkable film to form more microstructures during the stretching process, and improve the shrinkage uniformity of the PBSEHL heat shrinkable film.

[0028] (3) The microstructure formed by biaxial stretching in a humid environment can provide more attachment points and degradation channels for microorganisms, which can further increase the degradation rate of the PBSEHL heat shrinkable film.

[0029] (4) The double-pull down-blowing water-pull secondary expansion biodegradable heat shrinkable film production process provided in the present application can effectively improve the poor lateral shrinkage of PBSEHL heat shrinkable film, and provide a new solution to the problem of poor performance of other biodegradable heat shrinkable films. It is a very promising production process. DETAILED DESCRIPTION

[0030] The technical solutions in some embodiments of the present disclosure are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0031] Example 1

[0032] Follow these steps to prepare the filler masterbatch:

[0033] S11. After adding 4 parts of polylactic acid, 0.1 parts of antioxidant 1010 and 4 parts of silica powder to 5 parts of hexamethylene diisocyanate, magnetic stirring was performed for 30 minutes to obtain the filling masterbatch.

[0034] Example 2

[0035] Follow these steps to prepare the filler masterbatch:

[0036] S11. Add 5 parts of polylactic acid, 0.3 parts of antioxidant 1010, and 5 parts of silica powder to 6 parts of hexamethylene diisocyanate, and stir magnetically for 30 minutes to obtain the filling masterbatch.

[0037] Example 3

[0038] Follow these steps to prepare the filler masterbatch:

[0039] S11. After adding 6 parts of polylactic acid, 0.5 parts of antioxidant 1010 and 6 parts of silica powder to 7 parts of hexamethylene diisocyanate, magnetic stirring was performed for 30 minutes to obtain the filling masterbatch.

[0040] Example 4

[0041] Prepare PBSEHL heat shrink film as follows:

[0042] S21. 15 parts of EHL, 5 parts of the filler masterbatch prepared in Example 3 were added to 60 parts of PBS and mixed thoroughly to obtain the PBSEHL masterbatch;

[0043] S22. The PBSEHL masterbatch was added to a twin-screw extruder having a barrel temperature of 150°C for the first stage, 155°C for the second stage, 160°C for the third stage, 165°C for the fourth stage, 160°C for the fifth stage, and 150°C for the sixth stage with an aspect ratio of 30:1 and extruded at a speed of 70 r / min in a lip die having a thickness of 2.0 mm to obtain a composite material;

[0044] S23. After the composite material is first inflated by a downward blowing method, distilled water at 4°C is immediately used to cool the composite material by spraying, and the composite material is dried to obtain a primary expansion film;

[0045] S24. The primary expansion film is pulled using a roller at a speed of 10 m / min to form a tubular film having a folded diameter of 450 mm;

[0046] S25. The tube film is heated to 90°C, and after the second inflation is performed by the downward blowing method, distilled water at 15°C is immediately used to spray and cool the tube film, and the secondary expansion film is obtained after drying;

[0047] S26. The secondary expansion film is heated to 85° C. in an environment with a relative humidity of 90%, then stretched 3 times in the transverse direction and 2 times in the longitudinal direction, and then cooled by spraying with 4° C. distilled water, and then cut to obtain the PBSEHL heat shrinkable film.

[0048] Example 5

[0049] Follow the steps below to prepare PBSEHL heat shrink film:

[0050] S21. 20 parts of EHL, 10 parts of the filler masterbatch prepared in Example 2 were added to 65 parts of PBS and mixed thoroughly to obtain the PBSEHL masterbatch;

[0051] S22. The PBSEHL masterbatch was added to a twin-screw extruder having a barrel temperature of 155°C for the first stage, 160°C for the second stage, 165°C for the third stage, 170°C for the fourth stage, 165°C for the fifth stage, and 155°C for the sixth stage, and an aspect ratio of 35:1 was extruded at a speed of 75 r / min in a lip die having a thickness of 2.2 mm to obtain a composite material;

[0052] S23. After the composite material is first inflated by a downward blowing method, distilled water at 6°C is immediately used to cool the composite material by spraying, and the composite material is dried to obtain a primary expansion film;

[0053] S24. Using a roller to pull the primary expansion film at a speed of 13m / min to form a tubular film having a folded diameter of 475mm;

[0054] S25. The tube film is heated to 95°C, and after the second inflation is performed by the downward blowing method, distilled water at 20°C is immediately used to spray and cool the tube film, and the secondary expansion film is obtained after drying;

[0055] S26. The secondary expansion film is heated to 90° C. in an environment with a relative humidity of 93%, then stretched 3.5 times in the transverse direction and 2.5 times in the longitudinal direction, and then cooled by spraying with 6° C. distilled water, and then cut to obtain the PBSEHL heat shrinkable film.

[0056] Example 6

[0057] Follow the steps below to prepare PBSEHL heat shrink film:

[0058] S21. 25 parts of EHL, 15 parts of the filler masterbatch prepared in Example 1 were added to 70 parts of PBS and mixed thoroughly to obtain the PBSEHL masterbatch;

[0059] S22. The PBSEHL masterbatch was added to a twin-screw extruder having a barrel temperature of 160°C for the first stage, 165°C for the second stage, 170°C for the third stage, 175°C for the fourth stage, 170°C for the fifth stage, and 160°C for the sixth stage, and an aspect ratio of 40:1 was extruded at a speed of 80 r / min in a lip die having a thickness of 2.4 mm to obtain a composite material;

[0060] S23. After the composite material is first inflated by a downward blowing method, distilled water at 8°C is immediately used to cool the composite material by spraying, and the composite material is dried to obtain a primary expansion film;

[0061] S24. Using a roller to pull the primary expansion film at a speed of 15m / min to form a tubular film having a folded diameter of 500mm;

[0062] S25. The tube film is heated to 100°C, and after the second inflation is performed by the downward blowing method, distilled water at 25°C is immediately used to spray and cool the tube film, and the secondary expansion film is obtained after drying;

[0063] S26. The secondary expansion film is heated to 95° C. in an environment with a relative humidity of 95%, then stretched 4 times in the transverse direction and 3 times in the longitudinal direction, and then cooled by spraying with 8° C. distilled water, and then cut to obtain the PBSEHL heat shrinkable film.

[0064] Comparative Example 1

[0065] Prepare PBSEHL heat shrink film as follows:

[0066] S21. 15 parts of EHL, 5 parts of the filler masterbatch prepared in Example 3 were added to 60 parts of PBS and mixed thoroughly to obtain the PBSEHL masterbatch;

[0067] S22. The PBSEHL masterbatch was added to a twin-screw extruder having a barrel temperature of 150°C for the first stage, 155°C for the second stage, 160°C for the third stage, 165°C for the fourth stage, 160°C for the fifth stage, and 150°C for the sixth stage with an aspect ratio of 30:1 and extruded at a speed of 70 r / min in a lip die having a thickness of 2.0 mm to obtain a composite material;

[0068] S23. After the composite material is first inflated by a downward blowing method, distilled water at 4°C is immediately used to cool the composite material by spraying, and the composite material is dried to obtain a primary expansion film;

[0069] S24. The primary expansion film is pulled using a roller at a speed of 10 m / min to form a tubular film having a folded diameter of 450 mm;

[0070] S26. The tube film is heated to 85° C. in an environment with a relative humidity of 90%, then stretched 3 times in the transverse direction and 2 times in the longitudinal direction, and then cooled by spraying with 4° C. distilled water, and then cut to obtain the PBSEHL heat shrink film.

[0071] Comparative Example 2

[0072] Prepare PBSEHL heat shrink film as follows:

[0073] S21. 15 parts of EHL, 5 parts of the filler masterbatch prepared in Example 3 were added to 60 parts of PBS and mixed thoroughly to obtain the PBSEHL masterbatch;

[0074] S22. The PBSEHL masterbatch was added to a twin-screw extruder having a barrel temperature of 150°C for the first stage, 155°C for the second stage, 160°C for the third stage, 165°C for the fourth stage, 160°C for the fifth stage, and 150°C for the sixth stage with an aspect ratio of 30:1 and extruded at a speed of 70 r / min in a lip die having a thickness of 2.0 mm to obtain a composite material;

[0075] S23. After the composite material is first inflated by a downward blowing method, distilled water at 4°C is immediately used to cool the composite material by spraying, and the composite material is dried to obtain a primary expansion film;

[0076] S24. The primary expansion film is pulled using a roller at a speed of 10 m / min to form a tubular film having a folded diameter of 450 mm;

[0077] S25. The tube film is heated to 90°C, and after the second inflation is performed by the downward blowing method, distilled water at 15°C is immediately used to spray and cool the tube film, and the secondary expansion film is obtained after drying;

[0078] S26. The secondary expansion film is heated to 85° C. in a dry environment, then stretched 3 times in the transverse direction and 2 times in the longitudinal direction, and then cooled by spraying with 4° C. distilled water, and then cut to obtain the PBSEHL heat shrinkable film.

[0079] Experimental Example 1

[0080] In order to further verify the superior performance of the fully biodegradable heat shrinkable film for commercial cigarette cartons of the present application, the inventor conducted a series of research experiments. After testing, the performance of the PBSEHL heat shrinkable film obtained in Examples 4 to 6 and Comparative Examples 1 to 2 is shown in Table 1:

[0081] Table 1

[0082]

[0083] It can be seen from Table 1 that the PBSEHL heat shrinkable film obtained by the double-pull down-blowing water-pull secondary expansion biodegradable heat shrinkable film production process provided by the present application not only has better mechanical properties, but also has better light transmittance, and can meet the packaging requirements of different fields. At the same time, the process of the present application not only improves the heat shrinkage rate of the heat shrinkable film, but also successfully solves the problem of poor lateral shrinkage effect.

[0084] The above is only a preferred embodiment of the present disclosure. It should be understood that the present disclosure is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present disclosure, and should be within the scope of protection of the claims attached to the present disclosure.

Claims

1. Double-pull down-blowing water-pull secondary expansion biodegradable heat shrink film production process, characterized in that: The following steps are involved: Weighing PBSEHL masterbatch and performing melt extrusion to obtain a composite material; After the composite material is first inflated, it is immediately first cooled to obtain a primary expanded film; Pulling the primary expansion film to form a tubular membrane; After heating and second inflating the tube film, immediately performing a second cooling to obtain a secondary expanded film; and The secondary expansion film is subjected to biaxial stretching and third cooling in a wet environment, and then cut to obtain the PBSEHL heat shrinkable film; Wherein, the methods adopted by the first inflation and the second inflation include a down-blowing process; The relative humidity of the humid environment is 90% to 95%.

2. The biodegradable heat shrinkable film production process according to claim 1, characterized in that: The components of the PBSEHL masterbatch include, by weight, 60 to 70 parts of polybutylene succinate (PBS), 15 to 25 parts of enzymatically hydrolyzed lignin (EHL), and 5 to 15 parts of filler masterbatch.

3. The biodegradable heat shrinkable film production process according to claim 2, characterized in that: The filler masterbatch comprises, by weight, 4 to 6 parts of lubricant, 5 to 7 parts of chain extender, 0.1 to 0.5 parts of antioxidant, and 4 to 6 parts of opening agent.

4. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The melt extrusion is completed in a twin-screw extruder, the aspect ratio of the twin-screw extruder is (30-40):1, the barrel temperature of the twin-screw extruder is 150-160°C in the first section, 155-165°C in the second section, 160-170°C in the third section, 165-175°C in the fourth section, 160-170°C in the fifth section, and 150-160°C in the sixth section, the rotation speed of the twin-screw extruder is 70-80r / min, and the lip die opening of the twin-screw extruder is 2.0-2.4mm.

5. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The traction speed is 10-15 m / min.

6. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The folded diameter of the tubular membrane is 450-500 mm.

7. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The heating temperature is 90-100°C.

8. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The temperature of the biaxial stretching is 85 to 95° C., the transverse stretching ratio of the biaxial stretching is 3 to 4 times, and the longitudinal stretching ratio of the biaxial stretching is 2 to 3 times.

9. The process for producing a biodegradable heat shrinkable film according to claim 1, characterized in that: The first cooling temperature is 4-8°C; The second cooling temperature is 15-25°C; The temperature of the third cooling is 4-8°C.

10. A PBSEHL heat shrinkable film produced by the biodegradable heat shrinkable film production process according to any one of claims 1 to 9.

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