Production method of flame-retardant BOPET optical base film

Abstract

The invention discloses a production method of a flame-retardant BOPET optical base film. The base film comprises an outer surface layer, a middle core layer and an inner surface layer, the outer surface layer is PET (Polyethylene Terephthalate); the middle core layer is composed of PET, GF, decabromodiphenyl ether, an antioxidant and phenylphosphonic acid cerium; and the inner surface layer is composed of PET, PEN and nano silicon dioxide. The PEN of the inner surface layer has more excellent mechanical and heat-resistant properties and can enhance PET, and the middle core layer uses decabromodiphenyl ether and cerium phenylphosphonate together for the PET / GF composite material, so that the flame retardant property of the composite material can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of optical films, in particular to a method for producing a flame-retardant BOPET optical base film. Background Art

[0002] An optical film is a film that has been processed on an optical base film through secondary processes such as coating, vapor deposition, lamination, and pressing, so that when a light beam propagates through its cross-section, it can meet specific functions when reflecting, transmitting, or polarizing the light beam. According to the properties of optical films, they are mainly divided into: reflective films, anti-reflection films (also called anti-reflection films), spectroscopic films, filter films, brightening films, diffusion films, polarizers (full name polarizers), etc. BOPET optical base film is a common optical base film. BOPET film has many characteristics such as chemical resistance, low air permeability, transparency, non-toxicity, folding resistance, high mechanical strength, and good temperature resistance. It is often used in backplane film groups. However, PET is easy to burn and produce droplets at high temperatures, which limits its application. Summary of the Invention

[0003] In view of the above-mentioned defects of the prior art, the object of the present invention is to provide a method for producing a flame-retardant BOPET optical base film.

[0004] To solve the above problems, the technical solution of the present invention is: a method for producing a flame-retardant BOPET optical base film, the base film comprising an outer surface layer, an intermediate core layer and an inner surface layer; The outer layer is PET; The middle core layer is composed of PET, GF, decabromodiphenyl ether, antioxidant, and cerium phenylphosphonate; The inner surface layer is composed of PET, PEN, and nano-silicon dioxide; The production method comprises the following steps: (1) Weigh the raw materials according to the proportions of the outer layer, middle core layer and inner surface layer; (2) The raw materials of the outer layer, the middle core layer and the inner surface layer are mixed separately and sent into respective extruders for mixing and plasticizing; (3) The molten melts are fed into the die heads respectively, and the melts are combined in the die heads and then pass through the flat die head mouth to form a molten sheet; (4) Using an air knife to attach the sheet to a chilled roller, the sheet is quenched to form an unshaped sheet, and then cooled in a water bath to form a cast sheet; (5) The cast sheet is stretched to form a film; (6) The film thickness is detected by infrared and the corresponding thickness deviation is fed back to the die head. The heating power of the corresponding bolt is slightly adjusted to correct the film thickness deviation. (7) Grafting azo polymer on the outer surface of the film; (8) Roll up the film.

[0005] Furthermore, the components of the outer layer, the middle core layer and the inner layer are as follows by mass: outer layer 20%, middle core layer 60%, inner layer 20%.

[0006] Furthermore, the components of the middle core layer are as follows by mass ratio: PET 77.7%, GF 14%, decabromodiphenyl ether 5%, antioxidant 0.3%, and cerium phenylphosphonate 3%.

[0007] Furthermore, the components of the inner surface layer are as follows by mass ratio: PET 90.5%, PEN 9%, and nano-silicon dioxide 0.5%.

[0008] Furthermore, in step (7), the azo polymer is an acrylic ester azobenzene monomer.

[0009] Furthermore, step (7) is specifically as follows: spin-plating the acrylic ester azobenzene monomer and the initiator on the surface of the outer layer, and forming a uniform film layer on the surface of the outer layer by a method of ultraviolet light-induced graft polymerization.

[0010] The present invention has the following beneficial effects: the intermediate core layer uses decabromodiphenyl ether and cerium phenylphosphonate together in the PET / GF composite material, which can greatly improve the flame retardant properties of the composite material. Decabromodiphenyl ether is a gas-phase flame retardant mechanism, and the flame retardant effect is mainly reflected in the first stage of thermal decomposition of the composite material. Bromine-containing groups that can be generated during the combustion process form more stable substances with the matrix, and the generated inert gases such as HBr will dilute the combustible gas and isolate a certain amount of oxygen, thereby preventing combustion; cerium phenylphosphonate is a condensed-phase flame retardant mechanism, and the flame retardant effect is mainly reflected in the second decomposition stage of thermal decomposition of the composite material. Its condensed-phase barrier effect prolongs the residence time of decabromodiphenyl ether and its decomposition products in the condensed phase, thereby enhancing its flame retardant effect, and can promote the deposition and coating of residual carbon on the GF surface, reducing the "core erosion" effect of GF, and further enhancing the flame retardant effect; The PEN in the inner surface layer has better mechanical and heat resistance properties and can strengthen PET; By grafting an azo polymer onto the surface of the outer layer of the film, a grafted film with photoresponsiveness can be obtained. The base film has both the strength of the polymer substrate and the photoresponsiveness of the azo surface layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the optical base film of the present invention.

[0012] As shown in the figure: 1 - outer surface layer, 2 - middle core layer, 3 - inner surface layer. DETAILED DESCRIPTION

[0013] In order to more intuitively and completely understand the technical solution of the present invention, a non-limiting description of the features of the present invention is now provided below in conjunction with the accompanying drawings: like Figure 1 As shown, a method for producing a flame-retardant BOPET optical base film, the base film includes an outer surface layer 1, an intermediate core layer 2 and an inner surface layer 3; The outer layer 1 is PET; The middle core layer 2 is composed of PET, GF, decabromodiphenyl ether, antioxidant, and cerium phenylphosphonate; The inner surface layer 3 is composed of PET, PEN, and nano-silicon dioxide; The production method comprises the following steps: (1) Weigh the raw materials according to the proportions of the outer layer, middle core layer and inner surface layer; (2) The raw materials of the outer layer, the middle core layer and the inner surface layer are mixed separately and sent into respective extruders for mixing and plasticizing; (3) The molten melts are fed into the die heads respectively, and the melts are combined in the die heads and then pass through the flat die head mouth to form a molten sheet; (4) Using an air knife to attach the sheet to a chilled roller, the sheet is quenched to form an unshaped sheet, and then cooled in a water bath to form a cast sheet; (5) The cast sheet is stretched to form a film; (6) The film thickness is detected by infrared and the corresponding thickness deviation is fed back to the die head. The heating power of the corresponding bolt is slightly adjusted to correct the film thickness deviation. (7) Grafting azo polymer on the outer surface of the film; (8) Roll up the film.

[0014] The composition of the outer layer, middle core layer, and inner layer by mass is: outer layer 20%, middle core layer 60%, inner layer 20%. The composition of the middle core layer by mass is: PET 77.7%, GF 14%, decabromodiphenyl ether 5%, antioxidant 0.3%, and cerium phenylphosphonate 3%. The antioxidant is antioxidant 1010.

[0015] The components of the inner surface layer are as follows by mass: PET 90.5%, PEN 9%, and nano-silicon dioxide 0.5%.

[0016] In step (7), the azo polymer is an acrylate azobenzene monomer. Step (7) specifically comprises: spin-plating the acrylate azobenzene monomer and the initiator on the surface of the outer layer, and using ultraviolet light to initiate graft polymerization to form a uniform film layer on the surface of the outer layer.

[0017] The middle core layer uses decabromodiphenyl ether and cerium phenylphosphonate together in the PET / GF composite material, which can greatly improve the flame retardant properties of the composite material. Decabromodiphenyl ether is a gas-phase flame retardant mechanism, and the flame retardant effect is mainly reflected in the first stage of thermal decomposition of the composite material. The bromine-containing groups that can be generated during the combustion process form more stable substances with the matrix, and the inert gases such as HBr generated will dilute the combustible gas and isolate a certain amount of oxygen, thereby preventing combustion; cerium phenylphosphonate is a condensed-phase flame retardant mechanism, and the flame retardant effect is mainly reflected in the second decomposition stage of thermal decomposition of the composite material. Its condensed-phase barrier effect will prolong the retention time of decabromodiphenyl ether and its decomposition products in the condensed phase, thereby enhancing its flame retardant effect. It can also promote the deposition and coating of residual carbon on the GF surface, reducing the "core erosion" effect of GF and further enhancing the flame retardant effect. The PEN in the inner surface layer has better mechanical and heat resistance properties and can strengthen PET; By grafting an azo polymer onto the surface of the outer layer of the film, a grafted film with photoresponsiveness can be obtained. The base film has both the strength of the polymer substrate and the photoresponsiveness of the azo surface layer.

Claims

1. A method for producing a flame-retardant BOPET optical base film, characterized in that: The basement membrane includes an outer surface layer, a middle core layer and an inner surface layer; The outer layer is PET; The middle core layer is composed of PET, GF, decabromodiphenyl ether, antioxidant, and cerium phenylphosphonate; The inner surface layer is composed of PET, PEN, and nano-silicon dioxide; The production method comprises the following steps: (1) Weigh the raw materials according to the proportions of the outer layer, middle core layer and inner surface layer; (2) The raw materials of the outer layer, the middle core layer and the inner surface layer are mixed separately and sent into respective extruders for mixing and plasticizing; (3) The molten melts are fed into the die heads respectively, and the melts are combined in the die heads and then pass through the flat die head mouth to form a molten sheet; (4) Using an air knife to attach the sheet to a chilled roller, the sheet is quenched to form an unshaped sheet, and then cooled in a water bath to form a cast sheet; (5) The cast sheet is stretched to form a film; (6) The film thickness is detected by infrared and the corresponding thickness deviation is fed back to the die head. The heating power of the corresponding bolt is slightly adjusted to correct the film thickness deviation. (7) Grafting azo polymer on the outer surface of the film; (8) Roll up the film.

2. The method for producing a flame-retardant BOPET optical base film according to claim 1, characterized in that: The components of the outer layer, the middle core layer and the inner surface layer are as follows by mass: outer layer 20%, middle core layer 60%, inner surface layer 20%.

3. The method for producing a flame-retardant BOPET optical base film according to claim 1, wherein: The components of the middle core layer are as follows by mass ratio: PET 77.7%, GF 14%, decabromodiphenyl ether 5%, antioxidant 0.3%, and cerium phenylphosphonate 3%.

4. The method for producing a flame-retardant BOPET optical base film according to claim 1, wherein: The components of the inner surface layer are as follows by mass: PET 90.5%, PEN 9%, and nano-silicon dioxide 0.5%.

5. The method for producing a flame-retardant BOPET optical base film according to claim 1, wherein: In step (7), the azo polymer is an acrylic ester azobenzene monomer.

6. The method for producing a flame-retardant BOPET optical base film according to claim 5, characterized in that: Step (7) is specifically as follows: spin-plating the acrylic ester azobenzene monomer and the initiator on the surface of the outer layer, and using ultraviolet light to initiate graft polymerization to form a uniform film layer on the surface of the outer layer.

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