High-barrier composite packaging film with antibacterial function

Abstract

The invention relates to the technical field of high-barrier composite packaging films, and discloses a high-barrier composite packaging film with an antibacterial function, which sequentially comprises a base layer, a nano composite barrier layer, an antibacterial functional layer and an outer protective layer from bottom to top, and the layers are tightly attached through a coated starch-based adhesive. According to the high-barrier composite packaging film with the antibacterial function, the cellulose nanowhiskers have the characteristics of high strength and high modulus and are mixed with the bio-based polylactic acid, so that the tensile strength and tear resistance of the bio-based polylactic acid can be remarkably improved, and the structural stability of the packaging film in the using process is guaranteed; nano titanium dioxide and nano cellulose aerogel are arranged in the nano composite barrier layer, so that the barrier property of the packaging film on oxygen and ultraviolet rays can be enhanced, and the packaging film also has a certain antibacterial effect; in addition, the nanocellulose aerogel has a loose porous structure, so that gas molecules can be effectively prevented from passing through, and the barrier property is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-barrier composite packaging films, and particularly to a high-barrier composite packaging film with antibacterial function. Background Art

[0002] With the continuous improvement of people's living standards and the progress of material culture, people have put forward higher requirements for food safety and quality. The commonly used LDPE film at present has excellent heat-sealing performance, mechanical properties and transparency, and has been widely used in the packaging field. However, the LDPE film has poor barrier performance, especially the barrier performance to oxygen, which is difficult to meet the requirements of packaging for foods with low moisture content and containing oils and fats. At the same time, ordinary LDPE films do not have antibacterial properties, and the above-mentioned disadvantages limit its application scope in the food packaging field. In order to ensure food safety while extending its shelf life, it is very necessary to prepare a composite packaging film with high barrier performance and antibacterial properties.

[0003] Therefore, the present invention provides a high-barrier composite packaging film with antibacterial function to solve the above-mentioned problems. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides a high-barrier composite packaging film with antibacterial function, which has the following advantages and solves the above problems.

[0006] (2) Technical Solutions

[0007] To achieve the above object, the present invention provides the following technical solution: A high-barrier composite packaging film with antibacterial function, comprising a base layer, a nano-composite barrier layer, an antibacterial function layer and an outer protective layer from bottom to top in sequence, and each layer is closely adhered through a coated starch-based adhesive.

[0008] Preferably, the base layer comprises raw materials in the following weight ratio: 800 - 900 parts of bio-based polylactic acid, 20 - 50 parts of plasticizer and 100 - 200 parts of cellulose nanocrystals, and the plasticizer is tributyl citrate.

[0009] Preferably, the nano-composite barrier layer comprises raw materials in the following weight ratio: 800 - 900 parts of polybutylene adipate-co-terephthalate, 60 - 100 parts of nano-titanium dioxide, 6 - 10 parts of dispersant and 40 - 60 parts of nano-cellulose aerogel, and the dispersant is polyvinylpyrrolidone.

[0010] Preferably, the antibacterial functional layer comprises raw materials in the following parts by weight: 400-500 parts of sodium alginate, 30-50 parts of tea polyphenols, 30-50 parts of antibacterial agent and 400-500 parts of chitosan. The thickness of the antibacterial functional layer is 12-18 μm, and the antibacterial agent is nano magnesium oxide.

[0011] Preferably, the outer protective layer comprises raw materials in the following parts by weight: 800-950 parts of polybutylene succinate and 5-15 parts of antioxidant. The antioxidant is a hindered phenol antioxidant, and the thickness of the outer protective layer is 11-12 μm.

[0012] Preferably, the preparation steps of the base layer are as follows: adding the dried cellulose nanowhiskers, bio-based polylactic acid particles and plasticizer into a high-speed mixer according to a predetermined ratio, and mixing at 80-90 °C for 15-20 minutes to uniformly disperse the cellulose nanowhiskers in the bio-based polylactic acid;

[0013] Then, the mixed material is put into a hot press, and hot pressing and forming operations are carried out at 180-190 °C and a pressure of 10-15 MPa. After the forming is completed, it is cooled to room temperature to obtain a base layer film.

[0014] Preferably, the preparation steps of the nano composite barrier layer are as follows: adding polybutylene adipate-co-terephthalate, nano titanium dioxide, nano cellulose aerogel and dispersant into a twin-screw extruder according to a ratio, setting the screw speed to 180-220 r / min, and the extrusion temperature from the feeding section to the head is 160 °C, 170 °C, 180 °C, 190 °C in turn to fully mix the raw materials to obtain a composite masterbatch;

[0015] The composite masterbatch is formed into a film through a casting machine, the casting temperature is controlled at 185-195 °C, and the temperature of the cooling roller is set at 25-30 °C to finally obtain a nano composite barrier layer film.

[0016] Preferably, the preparation steps of the antibacterial functional layer are as follows: dissolving sodium alginate and chitosan in deionized water respectively to prepare solutions with a mass fraction of 2-3%, then mixing the two solutions evenly in a ratio of 1:1, and then adding tea polyphenols and antibacterial agent, and continuously stirring to obtain a uniform mixed solution;

[0017] The mixed solution is evenly coated on a flat substrate and placed in an environment of 40-50 °C for drying for 12-24 hours to form an antibacterial functional layer film.

[0018] (III) Beneficial effects

[0019] Compared with the prior art, the present invention provides a high-barrier composite packaging film with antibacterial function, and has the following beneficial effects:

[0020] 1. The high-barrier composite packaging film with antibacterial function utilizes the high strength and high modulus characteristics of cellulose nanocrystals whiskers and is mixed with bio-based polylactic acid, which can significantly improve the tensile strength and tear resistance of bio-based polylactic acid, ensuring the structural stability of the packaging film during use.

[0021] By setting nano-titanium dioxide and nano-cellulose aerogel in the nano-composite barrier layer, it can not only enhance the barrier properties of the packaging film against oxygen and ultraviolet rays, but also has certain antibacterial effects; moreover, nano-cellulose aerogel has a loose and porous structure, which can effectively hinder the passage of gas molecules and further improve the barrier performance.

[0022] 2. The high-barrier composite packaging film with antibacterial function is prepared by blending sodium alginate and chitosan. Both are natural biopolymers with good film-forming properties and biocompatibility. On this basis, added tea polyphenols have excellent antioxidant and antibacterial properties, plus antibacterial agents, which can not only enhance the barrier effect of the packaging film against water vapor, but also effectively inhibit the growth of microorganisms in the package, prevent the oxidation and deterioration of the contents, and extend the shelf life.

[0023] Using a degradable polybutylene succinate film as the outer protective layer, while having good mechanical properties, water resistance and degradability, it can protect the internal layers from external physical wear and chemical erosion, and can be gradually degraded in the natural environment, reducing environmental pollution. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] Embodiment 1:

[0026] A high-barrier composite packaging film with antibacterial function includes a base layer, a nano-composite barrier layer, an antibacterial function layer and an outer protective layer from bottom to top in sequence, and each layer is closely adhered through a coated starch-based adhesive.

[0027] The base layer includes the following raw materials in parts by weight: 800 parts of bio-based polylactic acid, 20 parts of plasticizer and 100 parts of cellulose nanocrystals whiskers, and the plasticizer is tributyl citrate.

[0028] The preparation steps of the base layer are as follows: Add the dried cellulose nanocrystals whiskers, bio-based polylactic acid particles and plasticizer into a high-speed mixer according to the established ratio, and mix at 80 °C for 15 minutes to make the cellulose nanocrystals whiskers evenly dispersed in the bio-based polylactic acid.

[0029] Then put the mixed material into a hot press and perform hot pressing and forming operations at 180 °C and a pressure of 10 MPa. After the forming is completed, cool it to room temperature to obtain a base film;

[0030] The nano-composite barrier layer comprises raw materials in the following parts by weight: 800 parts of polybutylene adipate-co-terephthalate, 60 parts of nano-titanium dioxide, 6 parts of a dispersant, and 40 parts of nano-cellulose aerogel. The dispersant is polyvinylpyrrolidone;

[0031] The preparation steps of the nano-composite barrier layer are as follows: Add polybutylene adipate-co-terephthalate, nano-titanium dioxide, nano-cellulose aerogel, and the dispersant into a twin-screw extruder in proportion. Set the screw speed to 180 r / min, and the extrusion temperature is 160 °C, 170 °C, 180 °C, and 190 °C in sequence from the feeding section to the die head to fully mix the raw materials and obtain a composite masterbatch;

[0032] Perform film forming on the composite masterbatch through a casting machine. Control the casting temperature at 185 °C and set the temperature of the cooling roller at 25 °C to finally obtain a nano-composite barrier layer film;

[0033] The antibacterial functional layer comprises raw materials in the following parts by weight: 400 parts of sodium alginate, 30 parts of tea polyphenols, 30 parts of an antibacterial agent, and 400 parts of chitosan. The thickness of the antibacterial functional layer is 12 μm, and the antibacterial agent is nano-magnesium oxide;

[0034] The preparation steps of the antibacterial functional layer are as follows: Dissolve sodium alginate and chitosan in deionized water respectively to prepare solutions with a mass fraction of 2%. Then mix the two solutions evenly in a 1:1 ratio, and then add tea polyphenols and the antibacterial agent, and continuously stir to obtain a uniform mixed solution;

[0035] Evenly coat the mixed solution on a flat substrate and place it in an environment at 40 °C for drying for 12 hours to form an antibacterial functional layer film;

[0036] The outer protective layer comprises raw materials in the following parts by weight: 800 parts of polybutylene succinate and 5 parts of an antioxidant. The antioxidant is a hindered phenol antioxidant, and the thickness of the outer protective layer is 11 μm.

[0037] Example 2:

[0038] An antibacterial functional high-barrier composite packaging film, which comprises a base layer, a nano-composite barrier layer, an antibacterial functional layer, and an outer protective layer from bottom to top in sequence. Each layer is tightly adhered through a coated starch-based adhesive;

[0039] The base layer comprises raw materials in the following parts by weight: 900 parts of bio-based polylactic acid, 50 parts of a plasticizer, and 200 parts of cellulose nanocrystals. The plasticizer is tributyl citrate;

[0040] The preparation steps of the base layer are as follows: Add the dried cellulose nanowhiskers, bio-based polylactic acid particles, and plasticizer into a high-speed mixer in a given proportion, mix at 90 °C for 20 minutes to promote the uniform dispersion of cellulose nanowhiskers in bio-based polylactic acid;

[0041] Then put the mixed material into a hot press and perform hot pressing and forming operations at 190 °C and a pressure of 15 MPa. After the forming is completed, cool it to room temperature to obtain the base layer film;

[0042] The nano-composite barrier layer includes the following raw materials in parts by weight: 900 parts of polybutylene adipate-co-terephthalate, 100 parts of nano-titanium dioxide, 10 parts of dispersant, and 60 parts of nano-cellulose aerogel. The dispersant is polyvinylpyrrolidone;

[0043] The preparation steps of the nano-composite barrier layer are as follows: Add polybutylene adipate-co-terephthalate, nano-titanium dioxide, nano-cellulose aerogel, and dispersant into a twin-screw extruder in proportion, set the screw speed to 220 r / min, and the extrusion temperature from the feeding section to the head is 160 °C, 170 °C, 180 °C, 190 °C in sequence to fully mix the raw materials and obtain the composite masterbatch;

[0044] Form the composite masterbatch into a film through a casting machine, control the casting temperature at 195 °C, and set the temperature of the cooling roll to 30 °C to finally obtain the nano-composite barrier layer film;

[0045] The antibacterial functional layer includes the following raw materials in parts by weight: 500 parts of sodium alginate, 50 parts of tea polyphenols, 50 parts of antibacterial agent, and 500 parts of chitosan. The thickness of the antibacterial functional layer is 18 μm, and the antibacterial agent is nano-magnesium oxide;

[0046] The preparation steps of the antibacterial functional layer are as follows: Dissolve sodium alginate and chitosan in deionized water respectively to prepare solutions with a mass fraction of 3%, then mix the two solutions evenly in a 1:1 ratio, and then add tea polyphenols and antibacterial agent, and continuously stir to obtain a uniform mixed solution;

[0047] Coat the mixed solution evenly on a flat substrate and place it in an environment at 50 °C to dry for 24 hours to form the antibacterial functional layer film;

[0048] The outer protective layer includes the following raw materials in parts by weight: 950 parts of polybutylene succinate and 15 parts of antioxidant. The antioxidant is a hindered phenol antioxidant, and the thickness of the outer protective layer is 12 μm.

[0049] Example 3:

[0050] A high-barrier composite packaging film with antibacterial function, which comprises a base layer, a nano-composite barrier layer, an antibacterial functional layer and an outer protective layer from bottom to top, and each layer is closely adhered through a coated starch-based adhesive;

[0051] The base layer comprises raw materials with the following weight parts ratio: 850 parts of bio-based polylactic acid, 30 parts of plasticizer and 100 parts of cellulose nanocrystals, and the plasticizer is tributyl citrate;

[0052] The preparation steps of the base layer are as follows: adding the dried cellulose nanocrystals, bio-based polylactic acid particles and plasticizer into a high-speed mixer according to a set ratio, mixing at 90 °C for 15 minutes to uniformly disperse the cellulose nanocrystals in the bio-based polylactic acid;

[0053] Then, putting the mixed material into a hot press, performing hot pressing and forming operation at 180 °C and 15 MPa pressure, and after the forming is completed, cooling to room temperature to obtain a base layer film;

[0054] The nano-composite barrier layer comprises raw materials with the following weight parts ratio: 800 parts of polybutylene adipate-co-terephthalate, 100 parts of nano-titanium dioxide, 8 parts of dispersant and 50 parts of nano-cellulose aerogel, and the dispersant is polyvinylpyrrolidone;

[0055] The preparation steps of the nano-composite barrier layer are as follows: adding polybutylene adipate-co-terephthalate, nano-titanium dioxide, nano-cellulose aerogel and dispersant into a twin-screw extruder according to a ratio, setting the screw rotation speed to 200 r / min, and the extrusion temperature from the feeding section to the head is 160 °C, 170 °C, 180 °C, 190 °C in turn to fully mix each raw material to obtain a composite masterbatch;

[0056] Forming the composite masterbatch into a film through a casting machine, controlling the casting temperature at 190 °C, and setting the temperature of the cooling roller at 25 °C to finally obtain a nano-composite barrier layer film;

[0057] The antibacterial functional layer comprises raw materials with the following weight parts ratio: 500 parts of sodium alginate, 30 parts of tea polyphenols, 30 parts of antibacterial agent and 500 parts of chitosan, the thickness of the antibacterial functional layer is 18 μm, and the antibacterial agent is nano-magnesium oxide;

[0058] The preparation steps of the antibacterial functional layer are as follows: dissolving sodium alginate and chitosan in deionized water respectively to prepare solutions with a mass fraction of 2%, then mixing the two solutions evenly according to a ratio of 1:1, and then adding tea polyphenols and antibacterial agent, and continuously stirring to obtain a uniform mixed solution;

[0059] Coating the mixed solution evenly on a flat substrate and drying at 40 °C for 24 hours to form an antibacterial functional layer film;

[0060] The outer protective layer comprises raw materials in the following parts by weight ratio: 800 parts of polybutylene succinate and 5 parts of antioxidant. The antioxidant is a hindered phenol antioxidant, and the thickness of the outer protective layer is 11 μm.

[0061] The beneficial effects of the present invention are as follows: for the high-barrier composite packaging film with antibacterial function, by virtue of the high strength and high modulus characteristics of cellulose nanocrystals whiskers and mixing them with bio-based polylactic acid, the tensile strength and tear resistance of bio-based polylactic acid can be significantly improved, ensuring the structural stability of the packaging film during use;

[0062] By arranging titanium dioxide nanoparticles and nanocellulose aerogel in the nano-composite barrier layer, not only can the barrier performance of the packaging film against oxygen and ultraviolet rays be enhanced, but also it has a certain antibacterial effect; moreover, the nanocellulose aerogel has a loose and porous structure, which can effectively hinder the passage of gas molecules, further improving the barrier performance;

[0063] By blending sodium alginate and chitosan, both of which are natural biopolymers with good film-forming properties and biocompatibility. On this basis, the added tea polyphenols have excellent antioxidant and antibacterial properties. Together with the antibacterial agent, it can not only enhance the barrier effect of the packaging film against water vapor, but also effectively inhibit the growth of microorganisms inside the package, prevent the oxidation and deterioration of the contents, and extend the shelf life;

[0064] Using the degradable polybutylene succinate film as the outer protective layer, while having good mechanical properties, water resistance and degradability, it can protect the internal layers from external physical wear and chemical erosion, and can be gradually degraded in the natural environment, reducing environmental pollution.

[0065] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high barrier composite packaging film with antibacterial function, characterized in that: It includes, from bottom to top, a base layer, a nano-composite barrier layer, an antibacterial functional layer and an outer protective layer, and each layer is tightly bonded by a coated starch-based adhesive.

2. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The base layer comprises the following raw materials in proportion by weight: 800-900 parts of bio-based polylactic acid, 20-50 parts of plasticizer and 100-200 parts of cellulose nano whiskers, wherein the plasticizer is tributyl citrate.

3. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The nano composite barrier layer comprises the following raw materials in proportion by weight: 800-900 parts of polybutylene adipate-terephthalate, 60-100 parts of nano titanium dioxide, 6-10 parts of dispersant and 40-60 parts of nano cellulose aerogel, wherein the dispersant is polyvinyl pyrrolidone.

4. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The antibacterial functional layer comprises the following raw materials in proportion by weight: 400-500 parts of sodium alginate, 30-50 parts of tea polyphenols, 30-50 parts of antibacterial agent and 400-500 parts of chitosan. The thickness of the antibacterial functional layer is 12-18 μm, and the antibacterial agent is nano magnesium oxide.

5. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The outer protective layer comprises the following raw materials in the following weight proportions: 800-950 parts of polybutylene succinate and 5-15 parts of antioxidant, wherein the antioxidant is a hindered phenol antioxidant, and the thickness of the outer protective layer is 11-12 μm.

6. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The preparation steps of the base layer are as follows: adding the dried cellulose nano whiskers, bio-based polylactic acid particles and plasticizer into a high-speed mixer according to a predetermined ratio, and mixing at 80-90° C. for 15-20 minutes to make the cellulose nano whiskers evenly dispersed in the bio-based polylactic acid; Then the mixed material is put into a hot press and hot-pressed at 180-190° C. and 10-15 MPa. After the molding is completed, the mixed material is cooled to room temperature to obtain a base film.

7. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The preparation steps of the nano-composite barrier layer are as follows: adding polybutylene adipate-terephthalate, nano-titanium dioxide, nano-cellulose aerogel and a dispersant into a twin-screw extruder in proportion, setting the screw speed to 180-220 r / min, and the extrusion temperature from the feeding section to the die to 160° C., 170° C., 180° C. and 190° C. in sequence, so that the raw materials are fully mixed to obtain a composite masterbatch; The composite masterbatch is formed into a film by a tape casting machine, the tape casting temperature is controlled at 185-195° C., and the temperature of the cooling roller is set at 25-30° C., and finally a nano-composite barrier layer film is obtained.

8. The high barrier composite packaging film with antibacterial function according to claim 1, characterized in that: The preparation steps of the antibacterial functional layer are as follows: sodium alginate and chitosan are respectively dissolved in deionized water to prepare a solution with a mass fraction of 2-3%, then the two solutions are evenly mixed in a ratio of 1:1, tea polyphenols and antibacterial agents are added, and stirring is continued to obtain a uniform mixed solution; The mixed solution is evenly coated on a flat substrate and placed in a 40-50°C environment to dry for 12-24 hours to form an antibacterial functional layer film.