CN115850785A - Porous super-hydrophobic linear low-density polyethylene film for yogurt inner cover film and preparation method thereof - Google Patents

Abstract

The invention discloses a porous super-hydrophobic linear low-density polyethylene film for an inner film of a yoghourt cover and a preparation method thereof, wherein the surface of the porous super-hydrophobic linear low-density polyethylene film is of a porous structure, the contact angle between the surface of the film and water is 150-156 degrees, the rolling angle of water drops on the surface of the film is less than 10 degrees, and the adhesion rate of the film after being contacted with yoghourt is less than 0.5 percent. The preparation method comprises (1) mixing linear low density polyethylene, salt and white sugar, and granulating; (2) Extruding and rolling the linear low-density polyethylene master batch into a thick film; (3) Fixing the thick film on a longitudinal and transverse stretching frame, stretching the thick film into a thin film through a hot water pool, and cooling to obtain the product. The porous super-hydrophobic linear low-density polyethylene film has excellent super-hydrophobicity and acid-milk adhesion resistance, the preparation method does not use organic solvent, the raw materials can be used for food packaging, the preparation is simple and controllable, the cost is low, and the industrialization prospect is wide.

Description

Porous superhydrophobic linear low-density polyethylene film for yogurt lid inner film and its preparation method

technical field

The invention belongs to the technical field of polymer films, and in particular relates to a porous superhydrophobic linear low-density polyethylene film used for the inner film of yoghurt caps and a preparation method thereof.

Background technique

Yogurt is a very important food for all ages. It is usually in the form of a thick liquid. Most of the packaging is paper cups or plastic cups. The yogurt cups are usually covered with a yogurt cover film. The inner surface of the cover film is usually It is a linear low density polyethylene film. When opening the yogurt cover, people often find that a large amount of yogurt adheres to the inner membrane surface of the yogurt cover film, which needs to be scraped off from the inner film surface layer of the cover film with a spoon to eat, and it is difficult to scrape clean, so it is often seen in daily life. Interesting phenomena such as tongue licking yogurt cover film” occurred. The problem of yogurt sticking to the surface of the inner membrane of the cap membrane often leads to waste of yogurt. Therefore, there is a very broad market demand for developing a cap membrane inner membrane that can prevent yogurt from adhering.

Inspired by the lotus leaf effect, superhydrophobic films with water contact angles greater than 150° have attracted extensive attention in recent years. The typical characteristics of superhydrophobic membranes are: liquids or emulsions using water as a solvent or dispersant have large contact angles, small contact areas, and low adhesion on their surfaces. If it is possible to prepare a linear low-density polyethylene film with anti-yoghurt adhesion and use it for the inner film of the yoghurt cover film, it will definitely be favored by the market and consumers in general. However, according to current literature reports, most methods for preparing superhydrophobic linear low-density polyethylene films either use unenvironmentally friendly organic solvents, or the raw materials used are not suitable for food packaging, or the preparation methods are complicated and difficult for industrial application, or So far, there is no suitable method for applying superhydrophobic linear low-density polyethylene films to yogurt lids, using expensive equipment.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a porous superhydrophobic linear low-density film for the inner membrane of yogurt caps that does not use organic solvents, can be used for food packaging, is simple and controllable in preparation, and low in cost. Polyethylene film and method for its preparation.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A porous super-hydrophobic linear low-density polyethylene film used for the inner film of yogurt caps, the surface of the porous super-hydrophobic linear low-density polyethylene film has a porous structure, the pore diameter is 10nm to 200nm, and the contact angle between the film surface and water is 150 Between °-156 °, the rolling angle of water droplets on the surface of the film is less than 10 °, and the adhesion rate of the porous super-hydrophobic linear low-density polyethylene film after being in contact with yoghurt is less than 0.5%.

As a general technical design, the present invention also provides a kind of preparation method of the above-mentioned porous super-hydrophobic linear low-density polyethylene film for yoghurt cap inner membrane, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar evenly, and then granulate to obtain linear low-density polyethylene masterbatch; wherein, the mass ratio of linear low-density polyethylene, salt, and white sugar is 80-90:5- 10: 5~10;

(2) Extrude and calender the linear low-density polyethylene masterbatch to form a linear low-density polyethylene thick film with a thickness of 0.05 mm to 0.1 mm;

(3) Fix the linear low-density polyethylene thick film on the vertical and horizontal stretching racks, pass through the hot water pool at 90°C to 100°C, and stretch the thick film to a linear low density polyethylene with a thickness of 0.005mm to 0.02mm film, and hot water is used to fully dissolve salt and white sugar, and after cooling, a porous super-hydrophobic linear low-density polyethylene film used for the inner film of yogurt lids is obtained.

In the method for preparing the porous superhydrophobic linear low-density polyethylene film used for the inner film of yoghurt lid, preferably, in step (1), the particle diameter of the linear low-density polyethylene masterbatch is 0.5 mm to 5 mm.

In the method for preparing the porous superhydrophobic linear low-density polyethylene film used for the inner film of yoghurt lid, preferably, in step (3), the length of the hot water pool is 5 meters to 20 meters.

In the present invention, the linear low density polyethylene has a density of 0.918-0.935 g/cm ³ .

Compared with the prior art, the present invention has the advantages of:

1. The porous superhydrophobic linear low-density polyethylene film used for the inner film of yogurt caps of the present invention has excellent superhydrophobicity and anti-yogurt adhesion performance, and the adhesion rate of yogurt after contacting it is less than 0.5%.

2. The preparation method of the present invention does not use organic solvents, the raw materials can be completely used in food packaging, the preparation process is simple and controllable, the equipment investment cost is low, and it has great industrialization prospects.

Description of drawings

Fig. 1 is the scanning electron micrograph of the surface of the porous superhydrophobic linear low density polyethylene film used for the inner film of yogurt lid according to Example 1 of the present invention.

Fig. 2 is the surface contact angle test diagram of the porous superhydrophobic linear low-density polyethylene film used for the inner film of yogurt lid according to Example 1 of the present invention.

Fig. 3 is the surface contact angle test diagram of the porous superhydrophobic linear low density polyethylene film used for the inner film of yogurt lid according to Example 2 of the present invention.

Fig. 4 is the surface contact angle test diagram of the porous superhydrophobic linear low density polyethylene film used for the inner film of yogurt lid according to Example 3 of the present invention.

Fig. 5 is a test diagram of the surface contact angle of the porous superhydrophobic linear low density polyethylene film used for the inner film of yogurt cap according to Example 4 of the present invention.

Fig. 6 is a test diagram of the surface contact angle of the porous superhydrophobic linear low density polyethylene film used for the inner film of yogurt lid according to Example 5 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. All materials and instruments used in the following examples are commercially available.

Example 1

A kind of preparation method of the porous superhydrophobic linear low-density polyethylene film that is used for yoghurt cap inner film of the present invention, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar according to a mass ratio of 80:10:10, and granulate to form a linear low-density polyethylene masterbatch, and the particle diameter of the masterbatch is 0.5mm;

(2) extruding and calendering the linear low density polyethylene master batch into a thick film with a thickness of 0.05mm;

(3) The thick film is fixed on the vertical and horizontal stretching frame, and stretched to a linear low density polyethylene film with a thickness of 0.005mm under the condition of a hot water pool with a length of 5 meters and a temperature of 90°C. During the process, the hot water fully dissolves the salt and sugar in the film. After cooling, the porous superhydrophobic linear low-density polyethylene film used for the inner film of the yogurt lid is obtained. The microscopic appearance is shown in Figure 1, and the surface is Porous structure with a pore size of 10nm to 200nm. As shown in Figure 2, the contact angle between the surface of the porous superhydrophobic linear low density polyethylene film and water is 151°. The rolling angle is 9°, and the adhesion rate of yogurt after contacting with its surface is 0.48%.

Example 2

A kind of preparation method of the porous superhydrophobic linear low-density polyethylene film that is used for yoghurt cap inner film of the present invention, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar according to a mass ratio of 90:5:5, and granulate to form a linear low-density polyethylene masterbatch, and the particle diameter of the masterbatch is 5mm;

(2) extruding and calendering the linear low density polyethylene masterbatch into a thick film with a thickness of 0.1mm;

(3) Fix the thick film on the vertical and horizontal stretching frame, and stretch it to a linear low density polyethylene film with a thickness of 0.02mm under the condition of a hot water pool with a length of 20 meters and a temperature of 100°C. During the process, the hot water fully dissolves the salt and sugar in the film from the film, and after cooling, a porous super-hydrophobic linear low-density polyethylene film for the inner film of yogurt lids is obtained, with a pore size of 10nm to 200nm. As shown in Figure 3, the contact angle between its surface and water is 153°. The rolling angle is 7°, and the adhesion rate of yogurt after contacting with its surface is 0.42%.

Example 3

A kind of preparation method of the porous superhydrophobic linear low-density polyethylene film that is used for yoghurt cap inner film of the present invention, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar according to a mass ratio of 85:5:10, and granulate to form a linear low-density polyethylene masterbatch, and the particle diameter of the masterbatch is 3mm;

(2) extruding and calendering the linear low density polyethylene master batch into a thick film with a thickness of 0.08mm;

(3) Fix the thick film on the vertical and horizontal stretching frame, and stretch it to a linear low density polyethylene film with a thickness of 0.01mm under the condition of a hot water pool with a length of 15 meters and a temperature of 95°C. During the process, the hot water fully dissolves the salt and sugar in the film, and after cooling, a porous superhydrophobic linear low-density polyethylene film for the inner film of yogurt lids is obtained, with a pore size of 10nm to 200nm. As shown in Figure 4, the contact angle between its surface and water is 155°. The rolling angle is 5°, and the adhesion rate of yogurt after contacting with its surface is 0.37%.

Example 4

A kind of preparation method of the porous superhydrophobic linear low-density polyethylene film that is used for yoghurt cap inner film of the present invention, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar according to a mass ratio of 85:10:5, and granulate to form a linear low-density polyethylene masterbatch, and the particle diameter of the masterbatch is 2mm;

(2) extruding and calendering the linear low density polyethylene masterbatch into a thick film with a thickness of 0.07mm;

(3) Fix the thick film on the vertical and horizontal stretching frame, and stretch it to a linear low-density polyethylene film with a thickness of 0.008mm under the condition of a hot water pool with a length of 10 meters and a temperature of 100°C. During the process, the hot water fully dissolves the salt and sugar in the film, and after cooling, a porous superhydrophobic linear low-density polyethylene film for the inner film of yogurt lids is obtained, with a pore size of 10nm to 200nm. As shown in Figure 5, the contact angle between its surface and water is 156°. The rolling angle was 3°, and the sticking rate of yogurt after contacting with its surface was 0.35%.

Example 5

A kind of preparation method of the porous superhydrophobic linear low-density polyethylene film that is used for yoghurt cap inner film of the present invention, comprises the following steps:

(1) Mix linear low-density polyethylene, salt, and white sugar according to a mass ratio of 86:8:6, and granulate to form a linear low-density polyethylene masterbatch, and the particle diameter of the masterbatch is 3mm;

(2) extruding and calendering the linear low density polyethylene master batch into a thick film with a thickness of 0.09mm;

(3) Fix the thick film on the vertical and horizontal stretching frame, and stretch it to a linear low density polyethylene film with a thickness of 0.006mm under the condition of a hot water pool with a length of 15 meters and a temperature of 100°C. During the process, the hot water fully dissolves the salt and sugar in the film, and after cooling, a porous superhydrophobic linear low-density polyethylene film for the inner film of yogurt lids is obtained, with a pore size of 10nm to 200nm. As shown in Figure 6, the contact angle between its surface and water is 152°. The rolling angle is 6°, and the adhesion rate of yogurt after contacting with its surface is 0.43%.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the spirit and technical solutions of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solutions of the present invention, or modify them to be equivalent Variations of equivalent embodiments. Therefore, any simple modifications, equivalent replacements, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solutions of the present invention, still fall within the protection scope of the technical solutions of the present invention.

Claims (4)

1. The porous super-hydrophobic linear low-density polyethylene film for the inner film of the yoghourt cover is characterized in that the surface of the porous super-hydrophobic linear low-density polyethylene film is of a porous structure, the pore diameter is 10-200 nm, the contact angle between the surface of the film and water is 150-156 degrees, the rolling angle of water drops on the surface of the film is less than 10 degrees, and the adhesion rate of the porous super-hydrophobic linear low-density polyethylene film after being contacted with the yoghourt is less than 0.5 percent.

2. A method for preparing a porous superhydrophobic linear low density polyethylene film for use in an inner film of a yoghurt cap according to claim 1, comprising the steps of:

(1) Uniformly mixing linear low-density polyethylene, salt and white sugar, and then granulating to obtain linear low-density polyethylene master batches; wherein the mass ratio of the linear low-density polyethylene to the salt to the white sugar is 80-90: 5-10;

(2) Extruding and rolling the linear low-density polyethylene master batch to form a linear low-density polyethylene thick film with the thickness of 0.05 mm-0.1 mm;

(3) Fixing the linear low-density polyethylene thick film on a longitudinal and transverse stretching frame, passing through a hot water tank at 90-100 ℃, stretching the thick film to a linear low-density polyethylene film with the thickness of 0.005-0.02 mm, fully dissolving salt and white sugar by hot water, and cooling to obtain the porous super-hydrophobic linear low-density polyethylene film for the inner film of the yoghourt cover.

3. The method for preparing the porous super-hydrophobic linear low-density polyethylene film for the inner membrane of the yogurt cap as claimed in claim 2, wherein in the step (1), the particle size of the linear low-density polyethylene masterbatch is 0.5mm to 5mm.

4. The method for preparing a porous superhydrophobic linear low density polyethylene film for an inner film of a yogurt cap according to claim 2 or 3, wherein in the step (3), the length of the hot water pool is 5-20 m.

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