Production method of high-transparency low-haze BOPET (Biaxially Oriented Polyester) anti-fog film

Abstract

The invention discloses a production method of a high-transparency low-haze BOPET anti-fog film, the BOPET anti-fog film comprises a BOPET base film and an anti-fog coating coated on the surface of the BOPET base film, and the BOPET base film is composed of PET, PCTG, silicon dioxide and silicone oil. The antifogging coating is sprayed on the surface of the BOPET base film, so that the film has good antifogging performance.

Description

Technical Field

[0001] The invention relates to a production method of a high-transparency and low-fog BOPET anti-fog film. Background Art

[0002] PET is the abbreviation of polyethylene terephthalate, commonly known as polyester resin. PET has the advantages of high transparency and good gloss. It also has excellent gas barrier, oil barrier and fragrance retention properties. The tensile strength is 5 to 10 times that of PE and 3 times that of PA. It is widely used in the manufacture of synthetic polyester fibers and films, and can also be used as engineering plastics in machinery, electronics, automobiles, electrical appliance manufacturing and consumer products.

[0003] Anti-fog packaging materials are widely used in display packaging of fresh products with high water content, such as vegetables and fruits, because they can prevent water vapor from forming water mist on the surface of the material and affecting the transparency of the material. When general packaging materials are used to package such products, it is easy to produce water mist on the inner layer of the packaging film because the products themselves have a large water content. Water mist increases the haze of the packaging film and reduces its transparency, making it difficult for consumers to see the contents clearly, affecting the appearance and packaging effect of the product. In addition, PET also has the disadvantages of low heat resistance temperature and strength. Therefore, how to develop a BOPET anti-fog film that can improve heat resistance temperature and strength is the research direction of the staff in this field. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, an object of the present invention is to provide a method for producing a high-transparency and low-fog BOPET anti-fog film.

[0005] To solve the above problems, the technical solution of the present invention is: a method for producing a high-transparency and low-fog BOPET anti-fog film, wherein the BOPET anti-fog film comprises a BOPET base film and an anti-fog coating coated on the surface of the BOPET base film, wherein the BOPET base film is composed of PET, PCTG, silicon dioxide and silicone oil; The production method comprises the following steps: (1) First, mix the dried silica and silicone oil evenly, then add PET and PCTG into the mixture, and after mixing, send them into the extruder for mixing and plasticizing; (2) The molten melt is fed into the die, and the melt passes through the flat die orifice to form a molten sheet; (3) Using an air knife to attach the sheet to a chilled roller to quench it into an unshaped sheet, and then cooling it in a water bath to shape the sheet into a cast sheet; (4) The cast sheet is stretched to form a film to obtain a BOPET base film; (5) preparing an anti-fog coating, wherein the anti-fog coating is composed of water-based polyurethane, deionized water, tetraethyl orthosilicate, hydrochloric acid, anhydrous ethanol, and nano-silicon dioxide; (6) Spray the anti-fog coating on the surface of the BOPET base film and cure it at room temperature for 24 hours to form an anti-fog coating.

[0006] Furthermore, the components of the BOPET base film are as follows by mass ratio: PET 69%, PCTG 28%, silicon dioxide 2%, and silicone oil 1%.

[0007] Furthermore, the components of the anti-fog coating are as follows by mass ratio: 20% water-based polyurethane, 32% deionized water, 0.4% ethyl orthosilicate, 0.2% hydrochloric acid, 47% anhydrous ethanol, and 0.4% nano-silicon dioxide.

[0008] Furthermore, step (5) is specifically as follows: firstly, water-based polyurethane, deionized water and anhydrous ethanol are poured into a sealed container to prepare a mixed solution, and stirred for 20 minutes to form a uniform dispersion, and then ethyl orthosilicate and hydrochloric acid are poured into the above container, stirred for 20 minutes, and finally, nano-silica is added and stirred for 5 hours.

[0009] The beneficial effects of the present invention are: PET and silica blending can effectively improve the strength of PET at room temperature. PCTG has a higher glass transition temperature and exhibits higher heat resistance. Therefore, PET / PCTG / silicon dioxide blending material can not only improve the strength of PET at room temperature, but also improve its strength at higher temperatures. The waterborne polyurethane itself has high surface energy and has a certain hydrophilicity. Since the added nano-silica particles are hydrophilic particles, the surface wettability changes to hydrophilicity. When tetraethyl orthosilicate is hydrolyzed, micron-sized particles will be produced, which leads to an increase in the contact angle of the film surface. Due to the interaction between a small amount of tetraethyl orthosilicate hydrolysis products and the added nano-silica particles, a micro-nano fractal structure will be produced, which is beneficial to the transformation of the film surface wettability to super-hydrophilicity. Water droplets will spread on the film surface to form a water film, thereby eliminating the scattering of light, that is, the anti-fog coating has good anti-fog properties. Implementation

[0010] In order to more intuitively and completely understand the technical solution of the present invention, a non-limiting feature description is now provided as follows: A method for producing a high-transparency and low-fog BOPET anti-fog film, wherein the BOPET anti-fog film comprises a BOPET base film and an anti-fog coating coated on the surface of the BOPET base film, wherein the BOPET base film is composed of PET, PCTG, silicon dioxide and silicone oil; The production method comprises the following steps: (1) First, mix the dried silica and silicone oil evenly, then add PET and PCTG into the mixture, and after mixing, send them into the extruder for mixing and plasticizing; (2) The molten melt is fed into the die, and the melt passes through the flat die orifice to form a molten sheet; (3) Using an air knife to attach the sheet to a chilled roller to quench it into an unshaped sheet, and then cooling it in a water bath to shape the sheet into a cast sheet; (4) The cast sheet is stretched to form a film to obtain a BOPET base film; (5) preparing an anti-fog coating, wherein the anti-fog coating is composed of water-based polyurethane, deionized water, tetraethyl orthosilicate, hydrochloric acid, anhydrous ethanol, and nano-silicon dioxide; (6) Spray the anti-fog coating on the surface of the BOPET base film and cure it at room temperature for 24 hours to form an anti-fog coating.

[0011] The components of BOPET base film are as follows by mass ratio: PET 69%, PCTG 28%, silicon dioxide 2%, and silicone oil 1%.

[0012] The components of the anti-fog coating are as follows by mass ratio: 20% waterborne polyurethane, 32% deionized water, 0.4% tetraethyl orthosilicate, 0.2% hydrochloric acid, 47% anhydrous ethanol, and 0.4% nano-silicon dioxide. Step (5) is specifically as follows: firstly, waterborne polyurethane, deionized water, and anhydrous ethanol are poured into a sealed container to form a mixed solution, and stirred for 20 minutes to form a uniform dispersion, and then tetraethyl orthosilicate and hydrochloric acid are poured into the above container, stirred for 20 minutes, and finally, nano-silicon dioxide is added and stirred for 5 hours.

[0013] The blending of PET and silica can effectively improve the strength of PET at room temperature. PCTG has a higher heat resistance due to its higher glass transition temperature. Therefore, the PET / PCTG / silicon dioxide blend can not only improve the strength of PET at room temperature, but also improve its strength at higher temperatures.

[0014] The waterborne polyurethane itself has high surface energy and has a certain hydrophilicity. Since the added nano-silica particles are hydrophilic particles, the surface wettability changes to hydrophilicity. When tetraethyl orthosilicate is hydrolyzed, micron-sized particles are produced, which increases the contact angle of the film surface. Due to the interaction between a small amount of tetraethyl orthosilicate hydrolysis products and the added nano-silica particles, a micro-nano fractal structure is produced, which is beneficial to the transformation of the film surface wettability to super-hydrophilicity. Water droplets will spread on the film surface to form a water film, thereby eliminating the scattering of light, that is, the anti-fog coating has good anti-fog properties.

Claims

1. A method for producing a high-transparency, low-fog BOPET anti-fog film, characterized in that: The BOPET anti-fog film includes a BOPET base film and an anti-fog coating coated on the surface of the BOPET base film. The BOPET base film is composed of PET, PCTG, silicon dioxide and silicone oil. The production method comprises the following steps: (1) First, mix the dried silica and silicone oil evenly, then add PET and PCTG into the mixture, and after mixing, send them into the extruder for mixing and plasticizing; (2) The molten melt is fed into the die, and the melt passes through the flat die opening to form a molten sheet; (3) Using an air knife to attach the sheet to a chilled roller to quench it into an unshaped sheet, and then cooling it in a water bath to shape the sheet into a cast sheet; (4) The cast sheet is stretched to form a film to obtain a BOPET base film; (5) preparing an anti-fog coating, wherein the anti-fog coating is composed of water-based polyurethane, deionized water, tetraethyl orthosilicate, hydrochloric acid, anhydrous ethanol, and nano-silicon dioxide; (6) Spray the anti-fog coating on the surface of the BOPET base film and cure it at room temperature for 24 hours to form an anti-fog coating.

2. The method for producing a high-transparency, low-fog BOPET anti-fog film according to claim 1, characterized in that: The components of BOPET base film are as follows by mass ratio: PET 69%, PCTG 28%, silicon dioxide 2%, and silicone oil 1%.

3. The method for producing a high-transparency and low-fog BOPET anti-fog film according to claim 1, characterized in that: The components of the anti-fog coating are as follows by mass ratio: 20% water-based polyurethane, 32% deionized water, 0.4% ethyl orthosilicate, 0.2% hydrochloric acid, 47% anhydrous ethanol, and 0.4% nano-silicon dioxide.

4. The method for producing a high-transparency and low-fog BOPET anti-fog film according to claim 3, characterized in that: Step (5) is specifically as follows: firstly, water-based polyurethane, deionized water and anhydrous ethanol are poured into a sealed container to prepare a mixed solution, and stirred for 20 minutes to form a uniform dispersion, then ethyl orthosilicate and hydrochloric acid are poured into the container, stirred for 20 minutes, and finally, nano-silica is added and stirred for 5 hours.