阅读说明：本技术 一种温敏聚氨酯气相控释的抗氧化复合膜及其制备方法 (Temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane and preparation method thereof ) 是由 卢立新 潘嘹 蔡莹 丘晓琳 龙青 于 2019-10-27 设计创作，主要内容包括：本发明提供了一种温敏聚氨酯气相控释的抗氧化复合膜及其制备方法,该复合膜能通过对温度的智能响应实现不同温度下精油从膜中释放的量的控制,同时脂质体能对膜中精油的释放起良好控释作用,有效延长抗氧化作用时间。一种温敏聚氨酯气相控释的抗氧化复合膜的制备方法,其特征在于,首先选用PCL4000、PEG2000、MDI、1BDO等为主要原料,通过两步溶液嵌段共聚技术合成TSPU溶液；采用天然植物精油为抗氧化剂,通过脂质体技术将其包埋进行保护与控释；然后将TSPU溶液与经冷冻干燥的精油冻干脂质体混合流延作为具有智能调控功能的内层控释基材,最后将基材与外层阻隔层复合制得温敏聚氨酯气相控释抗氧化复合膜。(The invention provides a temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane and a preparation method thereof. A preparation method of a temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane is characterized in that firstly PCL4000, PEG2000, MDI, 1BDO and the like are selected as main raw materials, and TSPU solution is synthesized by a two-step solution block copolymerization technology; natural plant essential oil is used as an antioxidant, and is embedded by a liposome technology for protection and controlled release; and then mixing and casting the TSPU solution and the freeze-dried essential oil freeze-dried liposome to form an inner layer controlled-release base material with an intelligent control function, and finally compounding the base material and an outer layer barrier layer to prepare the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane.)

1. A preparation method of a temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane is characterized by comprising the following steps:

(1) preparation of temperature-sensitive polyurethane solution

Firstly, weighing and uniformly mixing polycaprolactone 4000, polyethylene glycol 2000 and 4,4 '-diphenylmethane diisocyanate, wherein the molar ratio of the mixture of the polycaprolactone 4000 and the polyethylene glycol 2000 to the 4, 4' -diphenylmethane diisocyanate is 1 (2 ~ 2.5.5), the molar ratio of the polycaprolactone 4000 to the polyethylene glycol 2000 is 1: 2, and the polycaprolactone 4000 to the polyethylene glycol 2000 react at 75 ~ 85 ℃ for 2 ~ 2.5.5 hours to obtain a temperature-sensitive polyurethane prepolymer, and adding N, N-dimethylformamide to ensure that the solid content of the system is 45 ~ 55 wt%;

secondly, adding 4,4 '-diphenylmethane diisocyanate and 1, 4' -butanediol for chain extension reaction, controlling the molar ratio of isocyanate groups to hydroxyl groups in the system to be 1:1, reacting at 75 ~ 85 ℃ for 2 ~ 2.5.5 h, and obtaining a transparent viscous temperature-sensitive polyurethane solution, wherein the solid content of the system is 25 ~ 35 wt%;

(2) preparation of freeze-dried liposome of essential oil

Weighing plant essential oil, soybean lecithin and cholesterol, fully dissolving in an organic solvent, uniformly mixing, wherein the mass ratio of the soybean lecithin to the cholesterol and the mass ratio of the soybean lecithin to the plant essential oil are both 2:1 ~ 10:1, the content of the soybean lecithin in the solution is 15 ~ 35mg/mL, removing the organic solvent by reduced pressure evaporation, adding a hydration solution and a surfactant, carrying out ultrasonic hydration on the solution to form a liposome suspension, carrying out ultrasonic crushing on the liposome suspension system, centrifuging, filtering with a filter membrane, and carrying out freeze drying to obtain an essential oil freeze-dried liposome;

(3) preparation of composite membranes

Adding the freeze-dried liposome of the essential oil into a temperature-sensitive polyurethane solution to prepare a temperature-sensitive polyurethane gas-phase controlled-release antioxidant membrane, wherein the mass ratio of the freeze-dried liposome of the essential oil to the temperature-sensitive polyurethane gas-phase controlled-release antioxidant membrane is 0.5 ~ 2%;

and compounding the temperature-sensitive polyurethane gas-phase controlled-release antioxidant film on the barrier film to prepare the composite film.

2. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, characterized in that: in the step (2), the plant essential oil is formed by mixing any one or more than two of rosemary essential oil, cinnamon essential oil, clove essential oil, tea tree essential oil and cardamom essential oil.

3. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, wherein the hydration solution in the step (2) is a phosphate buffer solution prepared according to the standard of Chinese pharmacopoeia 2005 edition, and the pH value is 6.5 ~ 7.4.4.

4. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, wherein the surfactant in the step (2) is one or two of polyvinylpyrrolidone and tween 80, the organic solvent is chloroform, the volume concentration of the tween 80 is 0% ~ 5%, and the concentration of the polyvinylpyrrolidone is 0 ~ 2 mg/mL.

5. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, characterized in that: and (3) ultrasonic hydration is carried out at the ultrasonic power of 250W in the step (2) and the ultrasonic time is 30 min.

6. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, characterized in that: and (3) in the step (2), the ultrasonic power of the ultrasonic crushing is 300w, the ultrasonic crushing is started for 3s, the ultrasonic crushing is stopped for 4s, the time is 15min, the speed is 5000rpm, and the ultrasonic crushing is centrifuged for 15 min.

7. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, wherein the freeze-drying conditions in the step (2) are that the pre-freezing temperature is set to-80 ℃, the pre-freezing time is set to 6 ~ 10h, and the freeze-drying time is set to 36 ~ 48 h.

8. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, characterized in that: the barrier film in the step (3) is any one or more than two of a high-temperature resistant polyester film, a biaxially oriented polyester film, a polypropylene film, a polyamide film and a polyvinyl chloride film.

9. The preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane according to claim 1, characterized in that: the compounding method in the step (3) is a coating method or a hot-pressing bonding method.

10. A temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane is characterized in that: which is prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention relates to an antioxidant active food packaging material, in particular to a temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite film and a preparation method thereof, belonging to the technical field of intelligent controlled-release active food packaging materials.

Background

In recent years, there has been growing interest in preparing antioxidative packaging materials by incorporating antioxidants into the polymer matrix or coating onto the surface of the polymer film, three forms, ①, by dissolving both in a suitable solvent and then applying the solution to the substrate by coating techniques, ②, by melting the polymer and using extrusion techniques, incorporating and mixing the antioxidant into the melt, ③, immobilizing the antioxidant on the film surface.

Because the migration of synthetic antioxidants may have negative effects on human health, the development of natural antioxidants attracts the extensive attention of researchers, the continuous search for new effective natural antioxidants is one of the important trends in the development of antioxidant activity packages of foods, and essential oil has abundant phenolic compounds, has both antioxidant and antibacterial activities, and is a substance with great prospect. The essential oil is used as a gas-phase antioxidant, can be diffused to any space in a package without contacting with food, can play a role in antioxidation protection on the surface of the food and the headspace environment in the package, and has high-efficiency antioxidant activity.

However, the release rate of the antioxidant cannot be greatly reduced only by adding the antioxidant into the packaging material, and in order to ensure the sustained release of the antioxidant in a relatively long period of time, more and more researchers at home and abroad begin to develop controlled-release antioxidant activity packages, wherein the liposome technology is favored by more and more researchers at home and abroad due to the characteristics of stability, no toxicity and slow release. The essential oil is extremely easy to volatilize and has special aromatic flavor, the essential oil is wrapped in the liposome form, the essential oil can be isolated from the external environment and slowly released from the liposome, the volatility of the essential oil can be reduced, the influence of the essential oil on the flavor of food can be reduced, the liposome can also protect the main active ingredients of the essential oil, the subcellular size of the liposome can reduce the resistance of the essential oil in the transmission process, and the antioxidant effect of the essential oil can be improved. Meanwhile, the incorporation of the essential oil liposome into the polymer matrix of the packaging film or the coating on the surface of the packaging film to prepare the antioxidant active packaging film is a new development direction.

The external circulation environment is changeable instantly, the internal environmental factors of the package are complex and difficult to detect, at present, most antioxidants in antioxidant activity packages are released immediately after the package preparation is finished, cannot be coordinated with the external environment change and the internal packaging factors, have no excitation mechanism for controlling the release, and cannot realize the intelligent controllable release in the whole circulation use process. The development of a novel intelligent response type controlled-release antioxidant packaging system can effectively realize the organic combination of packaging and food, realize the intelligent control release of antioxidants in the food circulation process according to needs, improve the safety and quality of the food and prolong the shelf life of the food, so that the preparation of the novel intelligent response type antioxidant active packaging film by combining natural antioxidant plant essential oil with a liposome technology and intelligent temperature response has important engineering value.

Disclosure of Invention

The invention provides a temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane and a preparation method thereof.

The technical scheme is that the preparation method of the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane is characterized by comprising the following steps of:

(1) preparation of Temperature Sensitive Polyurethane (TSPU) solution

Firstly, weighing polycaprolactone 4000 (PCL 4000), polyethylene glycol 2000 (PEG 2000) and 4,4 '-diphenylmethane diisocyanate (MDI) and uniformly mixing, wherein the molar ratio of the mixture of the polycaprolactone 4000 and the polyethylene glycol 2000 to the 4, 4' -diphenylmethane diisocyanate is 1 (2 ~ 2.5.5), the molar ratio of the polycaprolactone 4000 to the polyethylene glycol 2000 is 1: 2, and the reaction is carried out at 75 ~ 85 ℃ for 2 ~ 2.5.5 h to obtain a temperature-sensitive polyurethane prepolymer, and adding N, N-Dimethylformamide (DMF) to ensure that the solid content of the system is 45 ~ 55 wt%;

secondly, adding 4,4 '-diphenylmethane diisocyanate and 1, 4' -Butanediol (BDO) to carry out chain extension reaction, controlling the molar ratio of isocyanate (-NCO) to hydroxyl (-OH) in the system to be 1:1, reacting for 2 ~ 2.5.5 h at 75 ~ 85 ℃, and obtaining a transparent viscous temperature-sensitive polyurethane solution with the final solid content of 25 ~ 35 wt%;

(2) preparation of freeze-dried liposome of essential oil

Weighing plant essential oil, soybean lecithin and cholesterol, fully dissolving in an organic solvent, uniformly mixing, wherein the mass ratio of the soybean lecithin to the cholesterol and the mass ratio of the soybean lecithin to the plant essential oil are both 2:1 ~ 10:1, the content of the soybean lecithin in the solution is 15 ~ 35mg/mL, removing the organic solvent by reduced pressure evaporation, adding a hydration solution and a surfactant, carrying out ultrasonic hydration on the solution to form a liposome suspension, carrying out ultrasonic crushing on the liposome suspension system, centrifuging, filtering with a filter membrane, and carrying out freeze drying to obtain an essential oil freeze-dried liposome;

(3) preparation of composite membranes

Adding the freeze-dried liposome of the essential oil into a temperature-sensitive polyurethane solution to prepare a temperature-sensitive polyurethane gas-phase controlled-release antioxidant membrane, wherein the mass ratio of the freeze-dried liposome of the essential oil to the temperature-sensitive polyurethane gas-phase controlled-release antioxidant membrane is 0.5 ~ 2%;

and compounding the temperature-sensitive polyurethane gas-phase controlled-release antioxidant film on the barrier film to prepare the composite film.

Further, in the step (2), the plant essential oil is any one of rosemary essential oil, cinnamon essential oil, clove essential oil, tea tree essential oil and cardamom essential oil or is formed by mixing more than two of the rosemary essential oil, the cinnamon essential oil, the clove essential oil, the tea tree essential oil and the cardamom essential oil.

Further, the hydration solution in the step (2) is phosphate buffer solution prepared according to the standard of Chinese pharmacopoeia 2005 edition, and the pH value is 6.5 ~ 7.4.4.

Further, in the step (2), the surfactant is one or two of polyvinylpyrrolidone (PVP) and Tween 80, the organic solvent is chloroform, the volume concentration of the Tween 80 is 0% ~ 5%, and the concentration of the polyvinylpyrrolidone is 0 ~ 2 mg/mL.

Further, the ultrasonic crushing in the step (2) has the ultrasonic power of 300w, the starting time of 3s, the stopping time of 4s, the time of 15min, the speed of 5000rpm and the centrifugation time of 15 min.

Further, the ultrasonic hydration in the step (2) has ultrasonic power of 250W and ultrasonic time of 30 min.

Further, the conditions of the freeze-drying in the step (2) are that the pre-freezing temperature is set to-80 ℃, the pre-freezing time is set to 6 ~ 10h, and the freeze-drying time is set to 36 ~ 48 h.

Further, in the step (3), the barrier film is formed by compounding any one or more than two of a high-temperature resistant polyester film (PET film), a biaxially oriented polyester film (BOPET film), a polypropylene film (PP film), a polyamide film (PA film) and a polyvinyl chloride film (PVC film).

Further, the compounding method in the step (3) is a coating method or a hot-press bonding method.

A temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane is prepared by the preparation method.

Compared with the prior art, the invention has the following beneficial effects:

the temperature-sensitive polyurethane gas-phase controlled-release antioxidant composite membrane can realize intelligent regulation and control of the release of essential oil in the membrane through intelligent response to the external temperature within a certain temperature range, and can effectively slow down the release rate of the essential oil in the membrane through the controlled-release action of the liposome, prolong the antioxidant action time of the essential oil, achieve the long-acting antioxidant effect and further prolong the quality guarantee period of food; the temperature-sensitive polyurethane gas-phase controlled-release antioxidant film can realize dual controlled-release functions of intelligent temperature response controlled release and liposome controlled release, can effectively realize organic combination of packaging and food, realizes intelligent controlled release of antioxidants as required in the food circulation process, improves the safety and quality of food, and has important academic research value and engineering value.

Drawings

FIG. 1 shows DSC thermal analysis curves of TSPU film, A film, B film and C film in the example of the present invention.

FIG. 2 is an analysis of internal crystallization of TSPU, BOPET, A, B and C films in the examples of the present invention.

FIG. 3 shows the moisture permeability analysis of a TSPU film and a general polyurethane film (PU) in the embodiment of the present invention.

FIG. 4 is a graph showing the release profile of rosemary essential oil from membrane A at different temperatures in the examples of the present invention.

FIG. 5 is a graph showing the release profile of rosemary essential oil from pellicle C at different temperatures in accordance with the present invention.

Detailed Description

The present invention will be described in more detail with reference to examples.