Porous in-situ microfiber modified atmosphere preservative film as well as preparation method and application thereof

Abstract

The invention discloses a porous in-situ microfiber modified atmosphere preservative film as well as a preparation method and application thereof. The nanofiber porous film is prepared by combining an in-situ fiber forming technology with a solvent etching method, a good fresh-keeping effect of different fruits and vegetables is achieved by regulating and controlling the microstructure of the nanofiber porous film and accurately controlling the gas transmission rate, the fruits and vegetables can be kept fresh for 3-58 days, and a new method is provided for preparing the high-performance nanofiber porous fresh-keeping film. Meanwhile, the influence of the viscosity ratio, the fiber phase content, the traction rate and the rolling rate on the physical performance and the preservation effect of the preservative film is researched, and reference is provided for parameter selection of the porous in-situ microfiber modified atmosphere preservative film.

Description

Technical Field

[0001] The invention belongs to the technical field of thin films, and in particular relates to a porous in-situ microfiber gas-controlled fresh-keeping film and a preparation method and application thereof. Background Art

[0002] How to extend the shelf life of fresh fruits and vegetables has always been a concern. After being picked, fruits and vegetables also carry out life activities, absorbing O2 and consuming organic matter in the body to carry out metabolism to maintain life activities. At the same time, CO2 will be discharged, a certain amount of water vapor and trace amounts of gases such as ethylene, acetaldehyde, and ethanol will be produced, accompanied by the release of a certain amount of heat. For this reason, the preservation of fruits and vegetables must start from the essence of inhibiting the respiration of fruits and vegetables. At present, the commonly used methods for preserving fruits and vegetables are: low-temperature storage, film preservation, and controlled atmosphere preservation. Among them, the controlled atmosphere cling film is to achieve the purpose of inhibiting the respiration of fruits and vegetables by regulating the permeability of oxygen, carbon dioxide, and water vapor through the film, thereby extending the shelf life or storage period of fruits and vegetables. It is the most cost-effective way to preserve fruits and vegetables. The conventional method of preparing controlled atmosphere cling film is to form different microstructures after blending several different polymers, which in turn affects the gas permeability. For example, patent CN 116836467 discloses a gas-controlled cling film and its application. With hyperbranched polyethylene as the basic material, a three-dimensional mesh gas channel is built for the cling film. The crystallinity of polyethylene is reduced by adjusting the composition of hyperbranched polyethylene and branched polyethylene, and the gas channel is formed by the polyethylene branch chain to ensure the permeability of carbon dioxide and oxygen. By adjusting the amount of polyethylene vinyl acetate resin, the density distribution of the sea-island structure can be adjusted, thereby achieving the adjustment of the water permeability of the cling film. In recent years, nanofiber porous membranes have many advantages such as high porosity, large specific surface area, high uniformity, and good connectivity between fiber pores. They have special gas regulation capabilities and can inhibit the respiration of fruits and vegetables. They have broad application prospects in the field of fruit and vegetable preservation.

[0003] Electrostatic spinning technology is the main method for preparing nanofiber porous membrane at present. It is to spray, stretch, split, solidify or volatilize the charged polymer melt or solution in a high-voltage electrostatic field to form fibers and randomly stack nanofiber porous membranes. The prepared nanofiber porous fresh-keeping film has also been used for fruit and vegetable preservation. For example, patent CN 111286870A discloses a preparation method of a degradable nanofiber antibacterial fresh-keeping film, which is prepared by spinning electrostatic spinning solution to prepare nanofiber fresh-keeping film, using TiO2 as a material reinforcing agent, using silk protein as an antibacterial agent, supplemented with edible fungus polysaccharides and thymol, for fruit and vegetable preservation. However, the influencing factors of electrostatic spinning technology are numerous, including the influence of the properties of the spinning solution itself and the influence of the external environment, including solution properties (concentration, conductivity, phase change heat, surface tension, etc.), spinning conditions (spinning voltage, speed, pore diameter, etc.), environmental factors (humidity, temperature, ambient air flow velocity), etc. Therefore, it is necessary to further explore new methods for preparing nanofiber porous membranes, achieve efficient preparation of nanofiber porous membranes, and promote their application in the field of fruit and vegetable preservation. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a porous in-situ microfiber modified atmosphere fresh-keeping film.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0008] The fiber phase and the matrix phase are evenly mixed, and the in-situ microfiber composite material is obtained by micro-nano stacking and co-extrusion;

[0009] The in-situ microfiber composite material is added into a boiling solvent, condensed and refluxed to prepare a porous in-situ microfiber modified atmosphere fresh-keeping film;

[0010] Wherein, the fiber phase comprises one of polypropylene, polylactic acid, polybutylene adipate terephthalate and nylon 6;

[0011] The matrix phase includes one of polyethylene terephthalate, ethylene-vinyl acetate copolymer, polyolefin elastomer, and polypropylene.

[0012] As a preferred embodiment of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, the viscosity ratio of the fiber phase to the matrix phase is 0.1-1.

[0013] As a preferred solution of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, the mass ratio of the fiber phase to the matrix phase is 5:95 to 40:60.

[0014] As a preferred embodiment of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, the solvent comprises one of xylene and dichloromethane.

[0015] As a preferred solution of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, wherein: the pulling rate of the micro-nano layered co-extrusion is 100-300 rpm.

[0016] As a preferred solution of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, wherein: the pulling rate of the micro-nano layered co-extrusion is 180-200 rpm.

[0017] As a preferred solution of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, wherein: the winding rate of the micro-nano layered co-extrusion is 50-90 rpm.

[0018] As a preferred solution of the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film of the present invention, wherein: the winding rate of the micro-nano layered co-extrusion is 60-80 rpm.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a porous in-situ microfiber modified atmosphere fresh-keeping film prepared by the method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide the use of the porous in-situ microfiber modified atmosphere fresh-keeping film in fruit and vegetable packaging.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention utilizes in-situ fiberization technology combined with a solvent etching method to prepare a nanofiber porous membrane. By regulating the microstructure of the nanofiber porous membrane, a good preservation effect of different fruits and vegetables is achieved, which can preserve the fruits and vegetables for 3 to 58 days. This provides a new method for the preparation of high-performance nanofiber porous cling film.

[0023] (2) The present invention explores the effects of viscosity ratio, fiber phase content, pulling rate, and winding rate on the physical properties and preservation effect of nanofiber porous cling film, providing a reference for the selection of parameters of porous in-situ microfiber modified atmosphere cling film. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0025] Figure 1 This is a SEM image of the porous in-situ microfiber modified atmosphere fresh-keeping film in Example 1 of the present invention.

[0026] Figure 2 The average diameter and diameter distribution diagram of the porous in-situ microfiber modified atmosphere fresh-keeping film in Examples 1-3 of the present invention.

[0027] Figure 3 This is a test diagram of the fresh-keeping effect of the porous in-situ microfiber modified atmosphere fresh-keeping film in Example 2 of the present invention.

[0028] Figure 4 This is a photo of cherries packed with the porous in-situ microfiber modified atmosphere cling film of Example 1 of the present invention when the shelf life has expired. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] Unless otherwise specified, the raw materials used in the examples were purchased commercially.

[0033] The carbon dioxide permeability rate and oxygen permeability rate in the present invention refer to GB / T1038-2000 Test method for gas permeability of plastic film and sheet - differential pressure method; the water vapor permeability rate refers to GB / T1037-1988 Test method for water vapor permeability of plastic film and sheet - cup method.

[0034] The test method for the preservation effect of the porous in-situ microfiber modified atmosphere preservative film of the present invention is as follows: select a batch of fruits that are intact, undamaged, consistent in hardness and color, and relatively uniform in size, divide them into equal parts at random, and seal them with the prepared film for preservation; observe the fruits visually every day at room temperature to see if they have problems such as water loss, shriveling, water leakage, and rotting; when the fruits begin to rot, the shelf life has expired.

[0035] Example 1

[0036] This embodiment provides a method for preparing a porous in-situ microfiber modified atmosphere fresh-keeping film.

[0037] Polypropylene (iPP) was used as the fiber phase, ethylene-vinyl acetate copolymer (EVA) was used as the matrix phase, and the viscosity ratio of iPP to EVA was adjusted to 0.53;

[0038] The fiber phase and the matrix phase are mixed evenly, and an in-situ microfiber composite material is formed by micro-nano lamination co-extrusion, the fiber phase content is 20%, the extrusion traction rate is regulated to be 180rpm, and the winding rate is regulated to be 60rpm;

[0039] The in-situ microfiber composite material was placed in boiling xylene and condensed and refluxed for 4 hours to etch the matrix phase in the in-situ microfiber composite material to obtain a porous in-situ microfiber modified atmosphere cling film.

[0040] Figure 1 This is the SEM image of the porous in-situ microfibrous modified atmosphere cling film.

[0041] Example 2

[0042] The difference between this embodiment and embodiment 1 is that the viscosity ratio of iPP to EVA is adjusted to 0.49, and other operations are the same as those in embodiment 1 to prepare a porous in-situ microfiber modified atmosphere cling film.

[0043] Example 3

[0044] The difference between this embodiment and embodiment 1 is that the viscosity ratio of iPP to EVA is adjusted to 0.66, and other operations are the same as those in embodiment 1 to prepare a porous in-situ microfiber modified atmosphere cling film.

[0045] The physical performance indicators of the porous in-situ microfiber modified atmosphere cling film of Examples 1-3 were measured, including carbon dioxide permeation rate, oxygen permeation rate and water vapor permeation rate. The test results are shown in Table 1.

[0046] Table 1 Comparison of physical properties of porous in-situ microfiber modified atmosphere cling film

[0047]

[0048] It can be seen from Table 1 that as the viscosity ratio increases, the fiber diameter decreases, the denser the stacking, the lower the permeability.

[0049] Figure 2 The average diameter and diameter distribution diagram of the porous in-situ microfiber modified atmosphere cling film of Examples 1-3 show that the diameter distribution of the cling film is more uniform when the viscosity ratio is 0.53.

[0050] The preservation effect of the porous in-situ microfiber modified atmosphere fresh-keeping film of Examples 1-3 was tested. Figure 3 The test results are shown in Table 2.

[0051] Table 2 Comparison of preservation effects of porous in-situ microfiber modified atmosphere cling film

[0052]

[0053] It can be seen from Table 2 that the porous in-situ microfiber modified atmosphere cling film in Example 1 has the best preservation effect on cherries. The main reason is that the permeability matches the respiration of cherries. Other viscosity ratios may be suitable for other fruits and vegetables. The permeability matches the gas ratio required when fruits and vegetables are dormant, and the preservation effect is better.

[0054] The photo of the porous in-situ microfiber modified atmosphere preservative film prepared in Example 1 when the cherries are packaged to the shelf life is as follows Figure 4 shown.

[0055] Example 4

[0056] This example explores the effect of fiber phase content on the physical properties and preservation effect of porous in-situ microfiber modified atmosphere cling film.

[0057] Polylactic acid (PLA) was used as the fiber phase and polyolefin elastomer (POE) was used as the matrix phase. The viscosity ratio of PLA to POE was 0.58.

[0058] The fiber phase and the matrix phase are uniformly mixed, and an in-situ microfiber composite material is formed by micro-nano lamination co-extrusion, the fiber phase content is adjusted to 5, 10, and 20wt%, the extrusion traction rate is adjusted to 180rpm, and the winding rate is adjusted to 60rpm;

[0059] The in-situ microfiber composite material was placed in boiling xylene and condensed and refluxed for 4 hours to etch the matrix phase in the in-situ microfiber composite material to obtain a porous in-situ microfiber modified atmosphere cling film.

[0060] The physical performance indicators of the porous in-situ microfiber modified atmosphere cling film were measured, and the test results are shown in Table 3.

[0061] Table 3 Comparison of physical properties of porous in-situ microfiber modified atmosphere cling film

[0062]

[0063] It can be seen from Table 3 that the increase in dispersed phase content and fiber diameter will increase the transmittance, but the more fibers there are, the greater the impact on the transmittance. The denser the stacking, the lower the transmittance.

[0064] The preservation effect of the porous in-situ microfiber modified atmosphere cling film was tested, and the test results are shown in Table 4.

[0065] Table 4 Comparison of preservation effects of porous in-situ microfiber modified atmosphere cling film

[0066]

[0067] It can be seen from Table 4 that the preservation effect of Pleurotus eryngii is best when the fiber content is 5%.

[0068] Example 5

[0069] This example explores the effect of extrusion pulling rate on the physical properties and preservation effect of porous in-situ microfiber modified atmosphere cling film.

[0070] Polybutylene adipate terephthalate (PBAT) was used as the fiber phase and polylactic acid (PLA) was used as the matrix phase. The viscosity ratio of PBAT to PLA was 0.61.

[0071] The fiber phase and the matrix phase are mixed evenly, and an in-situ microfiber composite material is formed by micro-nano lamination co-extrusion, the fiber phase content is 30%, the extrusion traction rate is adjusted to 150, 180, 200 rpm, and the winding rate is 60 rpm;

[0072] The in-situ microfiber composite material was placed in dichloromethane and condensed at 80°C for 2 hours to etch the matrix phase in the in-situ microfiber composite material to form a porous in-situ microfiber modified atmosphere cling film.

[0073] The physical performance indicators of the porous in-situ microfiber modified atmosphere cling film were measured, and the test results are shown in Table 5.

[0074] Table 5 Comparison of physical properties of porous in-situ microfiber modified atmosphere cling film

[0075]

[0076] It can be seen from Table 5 that the greater the extrusion pulling speed, the fiber diameter first decreases and then increases, which causes the permeability to first decrease and then increase.

[0077] The preservation effect of the porous in-situ microfiber modified atmosphere cling film was tested, and the test results are shown in Table 6.

[0078] Table 6 Comparison of preservation effects of porous in-situ microfiber modified atmosphere cling film

[0079]

[0080] It can be seen from Table 6 that when the pulling speed is 200 rpm, the plastic wrap has the best preservation effect on Sunshine Rose.

[0081] Example 6

[0082] This example explores the effect of extrusion winding rate on the physical properties and preservation effect of porous in-situ microfiber modified atmosphere cling film.

[0083] Nylon 6 (PA6) was used as the fiber phase and polypropylene (iPP) was used as the matrix phase. The viscosity ratio of PA6 to iPP was 0.54;

[0084] The fiber phase and the matrix phase are mixed evenly, and an in-situ microfiber composite material is formed by micro-nano lamination co-extrusion; the fiber phase content is 40%, the extrusion traction rate is regulated to be 180rpm, and the winding rates are regulated to be 50, 60, and 80rpm respectively;

[0085] The in-situ microfiber composite material was placed in xylene and condensed at 100°C for 4 hours to etch the matrix phase in the in-situ microfiber composite material to form a porous in-situ microfiber modified atmosphere cling film.

[0086] The physical performance indicators of the porous in-situ microfiber modified atmosphere cling film were measured, and the test results are shown in Table 7.

[0087] Table 7 Physical performance indicators of porous in-situ microfiber modified atmosphere cling film

[0088]

[0089] It can be seen from Table 7 that the greater the winding speed, the fiber diameter first decreases and then increases, which will cause the permeability to first decrease and then increase.

[0090] The obtained porous in-situ microfiber modified atmosphere cling film was tested for its preservation effect, and the test results are shown in Table 8.

[0091] Table 8 Preservation effect of porous in-situ microfiber modified atmosphere cling film

[0092]

[0093] It can be seen from Table 8 that when the winding speed is 60 rpm, the preservation effect of honey plum is the best.

[0094] Comparative Example 1

[0095] This comparative example uses a conventional commercially available polyethylene cling film for comparison, and its oxygen permeability is 7609.6cc / m 2 d. Carbon dioxide permeability is 32945.5cc / m 2 d. Water vapor transmission rate: 4.33g / m 2 d, keep cherries fresh for 2 days.

[0096] The porous in-situ microfiber modified atmosphere cling film of Examples 1-6 has a significantly better preservation effect than conventional polyethylene cling film.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that the fiber phase is iPP, the matrix phase is polyethylene, and the other steps are the same as those in Example 1 to prepare a porous in-situ microfiber modified atmosphere fresh-keeping film.

[0099] The oxygen permeability of the prepared cling film is 7609.6cc / m 2 d. Carbon dioxide permeability is 32945.5cc / m 2 d. Water vapor transmission rate: 4.33g / m 2 ·d, can only keep cherries fresh for 1 day.

[0100] When the fiber phase and the matrix phase do not match, the viscosity ratio, addition amount and process parameters are not appropriate, it is difficult for the fiber phase to form continuous microfibers with a large aspect ratio in the matrix phase, resulting in the final porous in-situ microfiber modified atmosphere cling film material having many large defects and high air permeability. The gas atmosphere in the cling film is equivalent to that of air, which cannot inhibit the breathing of fruits and vegetables and has a poor preservation effect.

[0101] In summary, the present invention achieves a good preservation effect on different fruits and vegetables by controlling the microstructure and regulating the gas permeability, which can preserve the fruits and vegetables for 3 to 58 days. The effects of viscosity ratio, fiber phase content, pulling rate, and winding speed on the physical properties and preservation effect of the cling film are explored, providing a reference for the selection of parameters of the porous in-situ microfiber modified atmosphere cling film.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a porous in-situ microfiber modified atmosphere fresh-keeping film, characterized in that: include, The fiber phase and the matrix phase are evenly mixed, and the in-situ microfiber composite material is obtained by micro-nano stacking and co-extrusion; The in-situ microfiber composite material is added into a boiling solvent, condensed and refluxed to prepare a porous in-situ microfiber modified atmosphere fresh-keeping film; Wherein, the fiber phase comprises one of polypropylene, polylactic acid, polybutylene adipate terephthalate and nylon 6; The matrix phase includes one of polyethylene terephthalate, ethylene-vinyl acetate copolymer, polyolefin elastomer, and polypropylene.

2. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 1, characterized in that: The viscosity ratio of the fiber phase to the matrix phase is 0.1-1.

3. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 2, characterized in that: The mass ratio of the fiber phase to the matrix phase is 5:95 to 40:

60.

4. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 1, characterized in that: The solvent includes one of xylene and dichloromethane.

5. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 1, characterized in that: The pulling rate of the micro-nano layered co-extrusion is 100-300 rpm.

6. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 5, characterized in that: The pulling rate of the micro-nano stacking co-extrusion is 180-200 rpm.

7. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 6, characterized in that: The winding speed of the micro-nano layered co-extrusion is 50-90 rpm.

8. The method for preparing the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 7, characterized in that: The winding speed of the micro-nano layered co-extrusion is 60-80 rpm.

9. The porous in-situ microfiber controlled atmosphere fresh-keeping film prepared by the method for preparing the porous in-situ microfiber controlled atmosphere fresh-keeping film according to any one of claims 1 to 8.

10. Use of the porous in-situ microfiber modified atmosphere fresh-keeping film according to claim 9 in packaging of fruits and vegetables.

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