Production method of flame-retardant CPP film

Abstract

The invention discloses a production method of a flame-retardant CPP film. The flame-retardant CPP film is composed of an outer surface layer, a base layer and an inner surface layer. The outer surface layer is prepared from PP, basic magnesium sulfate whiskers, a nitrogen-phosphorus flame retardant, nano aluminum oxide, maleic anhydride grafted polypropylene, a coupling agent and zinc stearate; the base layer is composed of PP, PET, PP-g-AA and a nucleating agent; the inner surface layer is composed of PP, aluminum hydroxide and benzoic acid functionalized graphene. The material has good flame retardant property and good mechanical property.

Description

Technical Field

[0001] The invention relates to a method for producing a flame-retardant CPP film. Background Art

[0002] As a semi-crystalline thermoplastic polymer material, polypropylene has the advantages of good heat resistance, low density, stress cracking resistance, easy molding and processing, and low price. CPP film is cast polypropylene film, also known as unstretched polypropylene film. Pure polypropylene has defects such as becoming brittle at low temperatures, easy scratches on the surface, poor cold resistance, easy to burn when exposed to fire, and releasing a lot of black smoke, which limits the use of polypropylene in the packaging field. Therefore, how to develop a CPP film with certain mechanical strength and flame retardant effect is the research direction of the staff in this field. 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 CPP film.

[0004] To solve the above problems, the technical solution of the present invention is: a method for producing a flame retardant CPP film, the flame retardant CPP film is composed of an outer surface layer, a base layer and an inner surface layer; The outer layer is composed of PP, basic magnesium sulfate whisker, nitrogen-phosphorus flame retardant, nano-alumina, maleic anhydride grafted polypropylene, coupling agent, and zinc stearate; The base layer is composed of PP, PET, PP-g-AA and nucleating agent; The inner surface layer is composed of PP, aluminum hydroxide, and benzoic acid-functionalized graphene; The production method comprises the following steps: (1) Weigh the raw materials according to the components of the outer surface layer, base layer, and inner surface layer; (2) The nano-alumina of the outer layer is modified with a coupling agent and then mixed with other raw materials. The raw materials of the base layer and the inner surface layer are mixed separately and sent to their 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 opening to form a molten sheet; (4) 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 film; (5) Roll up the film.

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

[0006] Furthermore, the components of the outer layer are as follows by mass ratio: PP 67.6%, basic magnesium sulfate whisker 10%, nitrogen phosphorus flame retardant 7%, nano-alumina 8%, maleic anhydride grafted polypropylene 7%, coupling agent 0.2%, and zinc stearate 0.2%.

[0007] Furthermore, the components of the base layer are as follows by mass ratio: PP 83.9%, PET 12%, PP-g-AA 4%, and nucleating agent 0.1%.

[0008] Furthermore, the components of the inner surface layer are as follows by mass ratio: PP 59%, aluminum hydroxide 39.5%, and benzoic acid functionalized graphene 1.5%.

[0009] The beneficial effects of the present invention are: The modified nano-alumina on the outer layer can serve as an active point to firmly bond with the PP interface through chemical bonds or physical adsorption. Maleic anhydride grafted polypropylene further improves the interface compatibility of basic magnesium sulfate whiskers, nano-alumina and PP, reduces interface defects, forms physical entanglement points between basic magnesium sulfate whiskers, nano-alumina and PP molecular chains, inhibits the slippage of PP molecular chains caused by external forces, and improves the tensile properties of the composite material. The nitrogen-phosphorus flame retardant plays a flame retardant role, and the addition of nano-alumina increases the density of the expanded carbon layer. The dense expanded carbon layer adheres to the surface of the material to form a heat-insulating and oxygen-isolating protective layer, which prevents the exchange of combustible gases and heat inside and outside the material. Moreover, with the addition of nano-alumina, the thermal conductivity of the composite material increases, and the temperature of the surface of the material is quickly transferred to the inside of the material, which reduces the temperature of the surface of the composite material and weakens the decomposition of polypropylene on the surface of the material, thereby improving the flame retardant properties of the composite material. The base layer can be modified by blending PP and PET to improve the impact strength and mechanical properties of PP; When aluminum hydroxide in the inner layer is used as a flame retardant and blended with PP, the tensile properties of the composite material will decrease. However, after adding benzoic acid-functionalized graphene, the mechanical properties of the composite material can be improved because the benzoic acid-functionalized graphene sheets are easier to disperse in the PP matrix. 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 flame-retardant CPP film, the flame-retardant CPP film comprising an outer surface layer, a base layer and an inner surface layer; The outer layer is composed of PP, basic magnesium sulfate whisker, nitrogen-phosphorus flame retardant, nano-alumina, maleic anhydride grafted polypropylene, coupling agent, and zinc stearate; The base layer is composed of PP, PET, PP-g-AA and nucleating agent; The inner surface layer is composed of PP, aluminum hydroxide, and benzoic acid-functionalized graphene; The production method comprises the following steps: (1) Weigh the raw materials according to the components of the outer surface layer, base layer, and inner surface layer; (2) The nano-alumina of the outer layer is modified with a coupling agent and then mixed with other raw materials. The raw materials of the base layer and the inner surface layer are mixed separately and sent to their 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 opening to form a molten sheet; (4) 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 film; (5) Roll up the film.

[0011] The components of the outer layer, base layer and inner layer are in the following mass ratio: outer layer 20%, base layer 60%; inner layer 20%.

[0012] The components of the outer layer are as follows by mass ratio: PP 67.6%, basic magnesium sulfate whisker 10%, nitrogen phosphorus flame retardant 7%, nano-alumina 8%, maleic anhydride grafted polypropylene 7%, coupling agent 0.2%, zinc stearate 0.2%. The coupling agent is silane coupling agent KH-550. The nucleating agent is dibenzylidene sorbitol derivatives or phosphate metal salts.

[0013] The components of the base layer are as follows by mass ratio: PP 83.9%, PET 12%, PP-g-AA 4%, and nucleating agent 0.1%.

[0014] The components of the inner surface layer are as follows by mass ratio: PP 59%, aluminum hydroxide 39.5%, and benzoic acid functionalized graphene 1.5%.

[0015] The modified nano-alumina on the outer layer can serve as an active point to firmly bond with the PP interface through chemical bonds or physical adsorption. Maleic anhydride grafted polypropylene further improves the interface compatibility of basic magnesium sulfate whiskers, nano-alumina and PP, reduces interface defects, forms physical entanglement points between basic magnesium sulfate whiskers, nano-alumina and PP molecular chains, inhibits the slippage of PP molecular chains caused by external forces, and improves the tensile properties of the composite material. The nitrogen-phosphorus flame retardant plays a flame retardant role, and the addition of nano-alumina increases the density of the expanded carbon layer. The dense expanded carbon layer adheres to the surface of the material to form a heat-insulating and oxygen-isolating protective layer, which prevents the exchange of combustible gases and heat inside and outside the material. Moreover, with the addition of nano-alumina, the thermal conductivity of the composite material increases, and the temperature of the surface of the material is quickly transferred to the inside of the material, which reduces the temperature of the surface of the composite material and weakens the decomposition of polypropylene on the surface of the material, thereby improving the flame retardant properties of the composite material. The base layer can be modified by blending PP and PET to improve the impact strength and mechanical properties of PP; When aluminum hydroxide in the inner layer is used as a flame retardant and blended with PP, the tensile properties of the composite material will decrease. However, after adding benzoic acid-functionalized graphene, the mechanical properties of the composite material can be improved because the benzoic acid-functionalized graphene sheets are easier to disperse in the PP matrix.

Claims

1. A method for producing a flame retardant CPP film, characterized in that: The flame retardant CPP film consists of an outer surface layer, a base layer and an inner surface layer; The outer layer is composed of PP, basic magnesium sulfate whisker, nitrogen-phosphorus flame retardant, nano-alumina, maleic anhydride grafted polypropylene, coupling agent, and zinc stearate; The base layer is composed of PP, PET, PP-g-AA and nucleating agent; The inner surface layer is composed of PP, aluminum hydroxide, and benzoic acid-functionalized graphene; The production method comprises the following steps: (1) Weigh the raw materials according to the components of the outer surface layer, base layer, and inner surface layer; (2) The nano-alumina of the outer layer is modified with a coupling agent and then mixed with other raw materials. The raw materials of the base layer and the inner surface layer are mixed separately and sent to their 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 opening to form a molten sheet; (4) 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 film; (5) Roll up the film.

2. The method for producing a flame retardant CPP film according to claim 1, characterized in that: The components of the outer layer, base layer and inner layer are in the following mass ratio: outer layer 20%, base layer 60%; inner layer 20%.

3. The method for producing a flame retardant CPP film according to claim 1, characterized in that: The components of the outer layer are as follows by mass ratio: PP 67.6%, basic magnesium sulfate whisker 10%, nitrogen phosphorus flame retardant 7%, nano-alumina 8%, maleic anhydride grafted polypropylene 7%, coupling agent 0.2%, and zinc stearate 0.2%.

4. The method for producing a flame retardant CPP film according to claim 1, characterized in that: The components of the base layer are as follows by mass ratio: PP 83.9%, PET 12%, PP-g-AA 4%, and nucleating agent 0.1%.

5. The method for producing a flame retardant CPP film according to claim 1, characterized in that: The components of the inner surface layer are as follows by mass ratio: PP 59%, aluminum hydroxide 39.5%, and benzoic acid functionalized graphene 1.5%.