Production method of BOPA (biaxially oriented polyamide) film with high composite strength

Abstract

The invention discloses a production method of a high-composite-strength BOPA film. The BOPA film comprises a surface layer, a middle layer and an inner layer, and the surface layer is composed of PA6, melamine cyanurate, magnesium silicate, polytrimethylene terephthalate, POE-g-MAH and an antioxidant; the middle layer is composed of PA10 and PA12, multi-walled carbon nanotubes, pentadecyl phenol and surface modified cuprous oxide; the inner layer is prepared from PA6, glass fibers, phenolic resin, hollow glass beads, halloysite, an antioxidant and silicone. The BOPA film disclosed by the invention has relatively good composite strength.

Description

Technical Field

[0001] This invention relates to a method for producing a high-strength composite BOPA film. Background Technology

[0002] Polyamides can be classified into long-chain polyamides and short-chain polyamides according to the length of their carbon chains. Long-chain polyamides include PA12, PA10,10, and PA10,12. Compared with traditional short-chain polyamides, long-chain polyamides have better basic properties such as wear resistance, lubricity, and chemical corrosion resistance. PA10,12 has excellent wear resistance, good chemical corrosion resistance, and low water absorption, but its poor impact resistance limits its development and application. Summary of the Invention

[0003] In view of the deficiencies of the prior art, one object of the present invention is to provide a method for producing a high composite strength BOPA film.

[0004] To solve the above problems, the technical solution of the present invention is: a method for producing a high composite strength BOPA film, wherein the BOPA film includes a surface layer, an intermediate layer, and an inner layer; The surface layer is composed of PA6, melamine cyanurate, magnesium silicate, polypropylene terephthalate, POE-g-MAH, and antioxidants; The intermediate layer consists of PA10,12, multi-walled carbon nanotubes, pentadecylphenol, and surface-modified cuprous oxide; The inner layer is composed of PA6, glass fiber, phenolic resin, hollow glass microspheres, halloysite, antioxidants, and silicone. The production method includes the following steps: (1) The surface, intermediate, and inner layer raw materials are blended separately and then fed into their respective extruders for mixing and plasticizing; (2) The molten melt is fed into the die head separately. After the melt merges in the die head, it forms a molten sheet through the flat die head opening. (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Wind up the film.

[0005] Furthermore, the preparation method of the surface-modified cuprous oxide in the intermediate layer is as follows: cuprous oxide is added to a mixture of ethanol and deionized water, KH-550 silane coupling agent is added, the solution is dispersed in an ultrasonic disperser for 30 min, then heated to 80℃ and stirred for 5 h. After the reaction is completed, the product is centrifuged and washed with ethanol, and then freeze-dried to obtain surface-modified cuprous oxide.

[0006] Furthermore, the surface layer components are as follows by mass: PA6 76.5%, melamine cyanurate 9.5%, magnesium silicate 0.5%, polypropylene terephthalate 10%, POE-g-MAH 3%, and antioxidant 0.5%.

[0007] Furthermore, the components of the intermediate layer are as follows by mass ratio: PA10,12 78.5%, multi-walled carbon nanotubes 1.5%, pentadecylphenol 18.5%, and surface-modified cuprous oxide 1.5%.

[0008] Furthermore, the components of the inner layer are as follows by mass ratio: PA6 55.5%, glass fiber 26%, phenolic resin 7.5%, hollow glass microspheres 6%, halloysite 3%, antioxidant 0.5%, and silicone 1.5%.

[0009] The beneficial effects of this invention are: the melamine cyanurate and magnesium silicate on the surface have excellent synergistic flame-retardant effects on PA6, and also improve the tensile and flexural strength of the material to a certain extent; the addition of polypropylene terephthalate can significantly reduce the water absorption rate of the composite material; and the addition of compatibilizer POE-g-MAH can improve the two-phase compatibility between PA6 and polypropylene terephthalate, further reducing the water absorption rate. The cuprous oxide in the middle layer acts as an antibacterial agent. Surface-modified cuprous oxide can improve the dispersion of PA6 and cuprous oxide particles. The addition of surface-modified cuprous oxide helps to improve the stability of the composite material. The addition of multi-walled carbon nanotubes and pentadecylphenol greatly improves the elongation at break and impact strength of the composite material, and significantly improves the mechanical properties of the material. Pentadecylphenol regulates the hydrogen bond interaction between PA10 and PA12 molecules. At the same time, pentadecylphenol acts as a compatibilizer to improve the dispersion and interface of the reinforcing phase multi-walled carbon nanotubes. The inner layer of PA6 is reinforced with glass fiber, which effectively improves the material's mechanical strength, rigidity, and fatigue resistance. However, glass fiber can cause exposed fibers on the material surface. The addition of hollow glass microspheres can overcome the disadvantages of glass fiber, improve the exposed fibers, improve flow properties, reduce shrinkage deformation rate, and improve the material's wear resistance and scratch resistance. However, the addition of hollow glass microspheres will lead to a decrease in the material's mechanical properties. The addition of halloysite can solve the problem of decreased mechanical properties. The addition of halloysite can improve the material's mechanical properties, and the flexural strength, flexural modulus, tensile strength, and notched impact strength are all improved. Detailed Implementation

[0010] To provide a more intuitive and complete understanding of the technical solution of this invention, the following non-limiting features are described: A method for producing high-strength composite BOPA film, which includes a surface layer, an intermediate layer, and an inner layer. The surface layer is composed of PA6, melamine cyanurate, magnesium silicate, polypropylene terephthalate, POE-g-MAH, and antioxidants; The intermediate layer consists of PA10,12, multi-walled carbon nanotubes, pentadecylphenol, and surface-modified cuprous oxide; The inner layer is composed of PA6, glass fiber, phenolic resin, hollow glass microspheres, halloysite, antioxidants, and silicone. The production method of high composite strength BOPA film includes the following steps: (1) The surface, intermediate, and inner layer raw materials are blended separately and then fed into their respective extruders for mixing and plasticizing; (2) The molten melt is fed into the die head separately. After the melt merges in the die head, it forms a molten sheet through the flat die head opening. (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Wind up the film.

[0011] The preparation method of surface-modified cuprous oxide in the intermediate layer is as follows: cuprous oxide is added to a mixture of ethanol and deionized water, KH-550 silane coupling agent is added, the solution is dispersed in an ultrasonic disperser for 30 min, then heated to 80℃ and stirred for 5 h. After the reaction is complete, the product is centrifuged and washed with ethanol, and then freeze-dried to obtain surface-modified cuprous oxide. The purpose of surface modification of cuprous oxide is to achieve proper dispersion of nanoparticles in the polymer matrix and better compatibility between nanoparticles and the host polymer material. Surface treatment of nanoparticles not only allows them to be better dispersed and compatible in the polymer matrix, but also ensures a lasting chemical bond between two incompatible phases through chemical and physical interactions with the polymer matrix.

[0012] The components of the surface layer, intermediate layer, and inner layer are in the following mass ratio: surface layer 20%, intermediate layer 60%, and inner layer 20%.

[0013] The surface layer consists of the following components by mass ratio: PA6 76.5%, melamine cyanurate 9.5%, magnesium silicate 0.5%, polypropylene terephthalate 10%, POE-g-MAH 3%, and antioxidant 0.5%. The middle layer consists of the following components by mass ratio: PA10, 12 78.5%, multi-walled carbon nanotubes 1.5%, pentadecylphenol 18.5%, and surface-modified cuprous oxide 1.5%. The inner layer consists of the following components by mass ratio: PA6 55.5%, glass fiber 26%, phenolic resin 7.5%, hollow glass microspheres 6%, halloysite 3%, antioxidant 0.5%, and silicone 1.5%.

[0014] The surface layer uses antioxidant H161, and the inner layer uses antioxidant 1010.

[0015] The melamine cyanurate and magnesium silicate on the surface of this invention have excellent synergistic flame-retardant effects on PA6, and also improve the tensile and flexural strength of the material to a certain extent. This is because the addition of melamine cyanurate and magnesium silicate increases the frictional force between chain segments, and magnesium silicate has a complexing and cross-linking effect during PA6 processing, which further improves the tensile and flexural strength of the material. The addition of polypropylene terephthalate can significantly reduce the water absorption rate of the composite material, and the addition of the compatibilizer POE-g-MAH can improve the two-phase compatibility between PA6 and polypropylene terephthalate, further reducing the water absorption rate. Polypropylene terephthalate molecules themselves have extremely low water absorption rates, and when they react with PA6... During blending, on the one hand, the ester groups in the poly(propylene terephthalate) molecule and the amide groups in the nylon molecule will undergo hydrogen bonding association. Under the dual action of high temperature and twin-screw shear force, an ester-amide exchange reaction can occur, thereby producing a polar shielding effect and reducing the water absorption of the composite material. On the other hand, the addition of the compatibilizer POE-g-MAH can form a graft copolymer at the interface between PA6 and poly(propylene terephthalate) molecules, making the two polymers more tightly bonded together, thereby improving the compatibility of the two phases and further reducing the water absorption rate of the material. In this invention, cuprous oxide in the intermediate layer serves as an antibacterial agent. Surface-modified cuprous oxide can improve the dispersibility of PA6 and cuprous oxide particles, and the addition of surface-modified cuprous oxide helps improve the stability of the composite material. The addition of multi-walled carbon nanotubes and pentadecylphenol greatly improves the elongation at break and impact strength of the composite material, significantly enhancing its mechanical properties. Pentadecylphenol regulates the hydrogen bond interactions between PA10 and PA12 molecules, and as a compatibilizer, it can improve the dispersion and interfacial condition of the reinforcing phase multi-walled carbon nanotubes. This invention uses glass fiber reinforced PA6 as the inner layer, which effectively improves the material's mechanical strength, rigidity, and fatigue resistance. However, glass fibers can cause exposed fiber surfaces. The addition of hollow glass microspheres can overcome the disadvantages of glass fibers, improve fiber exposure, enhance flow properties, reduce shrinkage deformation rate, and improve the material's wear and scratch resistance. However, the addition of hollow glass microspheres can lead to a decrease in the material's mechanical properties (because hollow glass microspheres are micron-sized spherical structures with smooth surfaces, resulting in poor interfacial bonding with the PA6 matrix). The addition of halloysite can solve the problem of decreased mechanical properties. Halloysite can improve the material's mechanical properties, including flexural strength, flexural modulus, and tensile strength. Both strength and notched impact strength were improved (haloysite has good nano-size effect, large aspect ratio, high mechanical properties and good dispersibility, which can effectively disperse and transfer stress in composite materials, and improve the flexural strength of composite materials; the nanoparticles of halloysite can transfer and disperse stress well in composite materials, and the unique tubular structure of halloysite can better prevent crack propagation, thereby improving tensile strength; halloysite can effectively transfer and disperse stress in composite materials, and the large aspect ratio of halloysite can play a bridging role when microcracks are generated in composite materials, further consuming energy and preventing further crack propagation, thereby improving notched impact strength).

Claims

1. A method for producing a high-strength composite BOPA film, the BOPA film comprising a surface layer, an intermediate layer, and an inner layer, characterized in that: The surface layer is composed of PA6, melamine cyanurate, magnesium silicate, polypropylene terephthalate, POE-g-MAH, and antioxidants; The intermediate layer consists of PA10,12, multi-walled carbon nanotubes, pentadecylphenol, and surface-modified cuprous oxide; The inner layer is composed of PA6, glass fiber, phenolic resin, hollow glass microspheres, halloysite, antioxidants, and silicone. The production method includes the following steps: (1) The surface, intermediate, and inner layer raw materials are blended separately and then fed into their respective extruders for mixing and plasticizing; (2) The molten melt is fed into the die head separately. After the melt merges in the die head, it forms a molten sheet through the flat die head opening. (3) Use an air knife to attach the sheet to the cooling roller and cool it rapidly to form an unshaped sheet. Then, after cooling in a water bath, the sheet is shaped to form a cast sheet. (4) The cast sheet is stretched to form a thin film; (5) Wind up the film.

2. The method for producing high composite strength BOPA film according to claim 1, characterized in that: The preparation method of surface-modified cuprous oxide in the intermediate layer is as follows: cuprous oxide is added to a mixture of ethanol and deionized water, KH-550 silane coupling agent is added, the solution is dispersed in an ultrasonic disperser for 30 min, then heated to 80℃ and stirred for 5 h. After the reaction is completed, the product is centrifuged and washed with ethanol, and then freeze-dried to obtain surface-modified cuprous oxide.

3. The method for producing a high-strength composite BOPA film according to claim 1, characterized in that: The surface layer components, by mass ratio, are: PA6 76.5%, melamine cyanurate 9.5%, magnesium silicate 0.5%, polypropylene terephthalate 10%, POE-g-MAH 3%, and antioxidant 0.5%.

4. The method for producing a high-strength composite BOPA film according to claim 1, characterized in that: The components of the intermediate layer by mass ratio are: PA10,12 78.5%, multi-walled carbon nanotubes 1.5%, pentadecylphenol 18.5%, and surface-modified cuprous oxide 1.5%.

5. The method for producing a high-strength composite BOPA film according to claim 1, characterized in that: The inner layer consists of the following components by mass ratio: PA6 55.5%, glass fiber 26%, phenolic resin 7.5%, hollow glass microspheres 6%, halloysite 3%, antioxidant 0.5%, and silicone 1.5%.