Polymer/potassium permanganate composite film and preparation method thereof

Abstract

This present invention discloses a polymer/potassium permanganate composite film obtainable by a process comprising the steps of using silane coupling agent for surface treatment of potassium permanganate, mixing 0.15-0.75 g of modified potassium permanganate with 10-20 g of polymers together to obtain a mixture, and coating the mixture to obtain a composite film. The composite film can absorb ethylene generated by fruit, thus extending fruit ripening time, keeping fruit fresh. It can be widely used as food packaging materials. The composite film also has a good oxygen barrier property and has a good efficiency to remove bacteria. Therefore it can be widely used in the pharmaceutical industry. The preparation method is scientifically sound, simple, and has high level of operability, thus making it possible for batch preparation.

Claims

1. A process for preparing a polymer/potassium permanganate composite film, comprising the following steps: Step (1): mixing polymethylhydrosiloxane or KH-570 and zinc stearate with potassium permanganate well at a mass ratio of 1-3:1-3:100, then heating the mixture under the temperature of 130-150 C. for 20-40 minutes to obtain a modified potassium permanganate; Step (2): dissolving 0.15-0.75 g of modified potassium permanganate obtained from step (1) in 20 ml of N,N-dimethyl formamide or tetrahydrofuran, then ultrasonically dispersing the mixture for 10-30 minutes to obtain a modified potassium permanganate solution; Step (3): dissolving 10-20 g of polymer in 60 ml solvents, then swelling the mixture under the temperature of 70-90 C. for 10-14 hours, adding the modified potassium permanganate solution from step (2) into the mixture, stirring it well to remove air bubbles, and then letting it stand for a certain length of time to obtain a mixed solution; Step (4): coating the mixed solution obtained from step (3) on a glass plate, vacuum drying it under the temperature of 60-70 C. for 15-25 minutes, then drying it under the temperature of 70-90 C. for 4-6 hours in a drum wind dryer, and finally allowing it to cool down naturally.

2. The process of claim 1, wherein the polymer in step (3) is selected from one of the following: low density polyethylene, high density polyethylene, polypropylene, polyvinyl chloride, polyamide, thermoplastic polyurethane.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The present invention is further described in the following exemplified embodiments to illustrate the application of the principles of the invention. It is understood that the invention may be embodied otherwise without departing from such principles. The scope of the claims of the present invention expressly should not be limited to such exemplary or preferred embodiments.

Embodiment 1

(2) This embodiment provides a process for preparing a low density polyethylene/potassium permanganate composite film, comprising the following steps:

(3) Step (1): weigh 0.002 g of polymethylhydrosiloxane, 0.002 g of zinc stearate, and 0.15 g of potassium permanganate, mix them well, then heat the mixture under the temperature of 130 C. for 20 minutes in a vacuum drying oven to obtain a modified potassium permanganate;
Step (2): dissolve the obtained modified potassium permanganate from step (2) into 20 ml N,N-dimethyl formamide, then ultrasonically disperse the mixture for 20 minutes to obtain a modified potassium permanganate solution;
Step (3): dissolve 10 g low density polyethylene in 60 ml solvents, then allow the mixture to swell under the temperature of 70 C. for 10 hours, add the modified potassium permanganate solution from step (2) into the mixture, stir the mixture for 0.5 hours, then pour the mixture into a volumetric flask, suction filtrate the mixture to remove air bubbles, and then let it stand for 10 minutes to obtain a mixed solution;
Step (4): coat the mixed solution obtained from step (3) on a glass plate, vacuum dry it under the temperature of 60 C. for 15 minutes, and then dry it under the temperature of 70 C. for 4 hours in a drum wind dryer, finally allow it to cool down naturally to obtain a low density polyethylene/potassium permanganate composite film.

Embodiment 2

(4) This embodiment provides a process for preparing a polyvinyl chloride/potassium permanganate composite film, comprising the following steps:

(5) Step (1): weigh 0.004 g of KH-570 silane coupling agent, 0.004 g of zinc stearate, and 0.75 g of potassium permanganate, mix them well, then heat the mixture under the temperature of 150 C. for 40 minutes in a vacuum drying oven to obtain a modified potassium permanganate;
Step (2): dissolve the obtained modified potassium permanganate from step (1) into 20 ml tetrahydrofuran, then ultrasonically disperse the mixture for 40 minutes to obtain a modified potassium permanganate solution;
Step (3): dissolve 20 g of polyvinyl chloride in 60 ml solvents, then allow the mixture to swell under the temperature of 90 C. for 14 hours, add the modified potassium permanganate solution from step (2) into the mixture, stir the mixture for 1.5 hours, then pour the mixture into a volumetric flask, suction filtrate the mixture to remove air bubbles, and then let it stand for 10 minutes to obtain a mixed solution;
Step (4): coat the mixed solution obtained from step (3) on a glass plate, vacuum dry it under the temperature of 70 C. for 25 minutes, and then dry it under the temperature of 90 C. for 6 hours in a drum wind dryer, finally allow it to cool down naturally to obtain a polyvinyl chloride/potassium permanganate composite film.

Embodiment 3

(6) This embodiment provides a process for preparing a thermoplastic polyurethane/potassium permanganate composite film, comprising the following steps:

(7) Step (1): weigh 0.003 g of polymethylhydrosiloxane, 0.003 g of zinc stearate, and 0.45 g of potassium permanganate, mix them well, then heat the mixture under the temperature of 140 C. for 30 minutes in a vacuum drying oven to obtain a modified potassium permanganate;
Step (2): dissolve the obtained modified potassium permanganate from step (1) into 20 ml N,N-dimethyl formamide, then ultrasonically disperse the mixture for 30 minutes to obtain a modified potassium permanganate solution;
Step (3): dissolve 15 g thermoplastic polyurethane in 60 ml solvents, then allow the mixture to swell under the temperature of 80 C. for 12 hours, add the modified potassium permanganate solution from step (2) into the mixture, stir the mixture for 1 hours, then pour the mixture into a volumetric flask, suction filtrate the mixture to remove air bubbles, and then let it stand for 10 minutes to obtain a mixed solution;
Step 4: coat the mixed solution obtained from step (3) on a glass plate, vacuum dry it under the temperature of 65 C. for 20 minutes, and then dry it under the temperature of 80 C. for 5 hours in a drum wind dryer, finally allow it to cool down naturally to obtain a thermoplastic polyurethane/potassium permanganate composite film.

(8) The above films have a thickness of 0.130.005 mm.

(9) The properties of the obtained polymer/potassium permanganate composite film from the above embodiments have been tested.

(10) (1) The Oxygen Permeance Test

(11) The obtained composite film's oxygen permeance ratio was tested by the oxygen permeance measuring instrument produced by Guangzhou West Tang Electromechanical Co., LTD according to GB/T 1038-2000.

(12) (2) The Oil Absorption Test

(13) The obtained composite film was been processed into a slice of 0.13 mm2.5 cm2.5 cm, and then vacuum dried the slice under the temperature of 70 C. for 20 hours. The dried slice was weighed and recorded as W.sub.1. Then the slice was immersed into a beaker containing a mixture of toluene and xylene. The beaker was heated in water bath at the temperature of 70 C. for 24 hours. Then the slice was taken out and quickly weighed, and the weight was recorded as W.sub.2. The above test was repeated for 3 times. Take four samples in each group, and take the mean. The oil absorption ratio was calculated based on the formula:
oil absorption=[(W.sub.2W.sub.1)/W.sub.1]%.
(3) The Ethylene Absorption Test
First, the obtained composite film was used to make a packaging bag. Then fresh green ripe bananas were placed into the packaging bag and the bag was sealed. For comparison, same experiment was also carried out using a bag made of polymer film without potassium permanganate. The two bags were placed in an air dry oven under the temperature of 25 C. for 10 days. The color of banana peek was observed in the end of the experiment.

(14) The test results of properties of the obtained films from the above embodiments are shown in Table 1:

(15) TABLE-US-00001 Comparison Test items Embodiment 1 Embodiment 2 Embodiment 3 experiment Oxygen 238.45 347.76 231.45 / permeation rate/ cc/m.sup.2.24 h.0.1 MPa Oil absorption 0.0013 0.0023 0.0011 / Rate (%) Change of color of Not yellow Little yellow Little yellow Obviously banana peels yellow