An open master pellet for super-smooth optical film and an optical film

Abstract

The application relates to the technical field of optical film materials, and particularly discloses an open master batch for super-smooth optical films, and an optical film prepared from the open master batch. The open master batch with uniform distribution of open agent powder is prepared by modifying the open agent powder and then using the modified open agent powder to prepare the open master batch. The optical film prepared from the open master batch has good opening property, and the films are not bonded together, and are easy to wind and cut. The optical film has uniform distribution of open agent on the surface, low roughness, high flatness, is smoother and has fewer surface defects, and has excellent optical performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical film materials, in particular to an opening master batch for super-smooth optical film, and also relates to an optical film prepared by using the opening master batch. BACKGROUND

[0002] The two main reasons for easy adhesion between plastic films are: first, a large number of exposed molecular chains exist on the surface of the film after film forming, and when two films are closed, the exposed molecular chains are intertwined with each other, so that the films are adhered and cannot be opened; second, a vacuum tight state is formed between the films after the films are closed, so that the films are not easy to separate. In order to solve the problem of adhesion of plastic films, adding inorganic anti-adhesion opening agent to the film is a common method. The addition of the opening agent can cause granular protrusions on the surface of the film, thereby reducing the negative pressure between the films and making the films easy to separate. At the same time, the granular protrusions on the surface of the film can reduce the contact area between the exposed molecular chains on the surface of the film, hinder the entanglement of the molecular chains between the film layers, and prevent the adhesion of the film.

[0003] However, the protrusions on the surface of the film caused by the addition of inorganic anti-adhesion opening agent to the film can also cause the roughness and flatness of the film surface to decrease, resulting in lower smoothness of the film surface. When applied to optical films, it can affect the optical performance of the prepared optical film. Therefore, when preparing super-smooth films, the opening property of the film should be fully considered, and as much as possible, nano-powder with smaller particle size should be selected as the opening agent. However, nano-powder is prone to agglomeration due to strong intermolecular forces, which can cause the opening property of the prepared film to decrease, and the winding and slitting performance to decrease; the protrusions caused by the agglomeration of the powder are larger and more obvious, which can easily cause defects on the film surface, decrease the optical performance, and cause a series of problems.

[0004] Based on the above problems, the present application aims to develop an opening master batch for super-smooth optical film to obtain an optical film with excellent opening performance and optical performance. SUMMARY

[0005] The technical problem solved by the present application is to provide an opening master batch for super-smooth optical film, and also to provide an optical film prepared by using the opening master batch.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: an opening master batch for super-smooth optical film, the preparation raw materials of which include the following raw materials in the following weight fractions:

[0007]

[0008] As an embodiment of the present application, the opening master batch for super-smooth optical film, the preparation raw materials of which include the following raw materials in the following weight fractions:

[0009]

[0010] As an embodiment of the present application, the ultra-smooth optical film is prepared from an opening master batch, and the raw materials include the following components by weight:

[0011]

[0012] As an embodiment of the present application, the optical-grade polyethylene terephthalate is in the form of a pellet, and the intrinsic viscosity is 0.645-0.655 dL / g.

[0013] As an embodiment of the present application, the polyethylene terephthalate for bottles is in the form of a powder, and the intrinsic viscosity is 0.675-0.685 dL / g.

[0014] As an embodiment of the present application, the opening agent powder used in the modified opening agent powder is silicon dioxide and / or calcium carbonate.

[0015] The opening agent powder is in a spherical or spheroidal structure, and the average particle size of the opening agent powder is 30-80 nm.

[0016] As an embodiment of the present application, the modifier used in the modification is a compound of polyethylene glycol 400, sodium hexametaphosphate and polyvinylpyrrolidone. Preferably, the polyethylene glycol 400, sodium hexametaphosphate and polyvinylpyrrolidone are mixed in a mass ratio of (40-60):(25-40):(15-20). Further preferably, the polyethylene glycol 400, sodium hexametaphosphate and polyvinylpyrrolidone are mixed in a mass ratio of (40-50):(30-40):(15-20). Still further preferably, the polyethylene glycol 400, sodium hexametaphosphate and polyvinylpyrrolidone are mixed in a mass ratio of (40-50):(33-40):(17-20).

[0017] As an embodiment of the present application, the preparation step of the modified opening agent powder is as follows: adding the opening agent powder and the modifier into a solvent, stirring and then ultrasonic treatment to make the opening agent powder fully dispersed, evaporating the solvent, and then grinding and sieving to obtain the modified opening agent powder. Preferably, ethanol is used as the solvent.

[0018] As an embodiment of the present application, multi-stage sieving is used, preferably five-stage sieving.

[0019] As a specific embodiment of the present application, five layers of sieves are used for sieving, and the sieves are arranged in order from coarse to fine, preferably in the order of 10,000 mesh, 20,000 mesh, 30,000 mesh, 40,000 mesh and 50,000 mesh from coarse to fine.

[0020] As an embodiment of the present application, the mass ratio of the solvent, the opening agent powder and the modifier is (85-97):(2-10):(1-5); further, the mass ratio of the solvent, the opening agent powder and the modifier is (90-95):(5-10):(1-3).

[0021] As an embodiment of the present application, the antioxidant can be at least one selected from BOSF antioxidant 1010, antioxidant 168, antioxidant 1076, or Sumitomo Chemical antioxidant GA-80, TP-D.

[0022] The present application provides a preparation method of the opening master batch for the ultra-smooth optical film, which is prepared by a double screw mixing method, comprising the steps of:

[0023] S1: weighing each raw material according to the weight fraction;

[0024] The optical-grade polyethylene terephthalate particles are added from the main feeding port of the double screw mixing equipment, and the bottle-grade polyethylene terephthalate powder, the modified opening agent powder and the antioxidant are mixed uniformly first, and then added from the side feeding port of the double screw mixing equipment;

[0025] S2: melting and mixing the material in the double screw mixing equipment, and then extruding from the head of the double screw mixing equipment, first passing through cooling and traction, and then entering the pelletizing and drying system, and finally obtaining the opening master batch for the ultra-smooth optical film through pelletizing and drying.

[0026] The screw temperature of the double screw mixing equipment is 220-260℃, the screw rotation speed is 200-380rpm, and the thread combination is a strong shear combination.

[0027] The present application provides the application of the opening master batch for the ultra-smooth optical film in the preparation of optical film.

[0028] The present application further provides an optical film, which comprises the opening master batch for the ultra-smooth optical film provided by the present application. Specifically, the optical film is an ABA three-layer co-extrusion structure, which comprises a core layer (B) and surface layers (A) arranged on both sides of the core layer.

[0029] The preparation raw material of the surface layer comprises film-grade polyethylene terephthalate and the opening master batch for the ultra-smooth optical film, and the mass percentage content of the opening master batch for the ultra-smooth optical film in the preparation raw material of the surface layer is 2-10%.

[0030] The preparation raw material of the core layer is film-grade polyethylene terephthalate.

[0031] The total mass of the surface layer accounts for 20-30% of the total mass of the core layer and the surface layer.

[0032] The present application provides a preparation method of the optical film, comprising steps of:

[0033] (1) adding the preparation raw material of the surface layer from the auxiliary extruder hopper of the extrusion casting machine as the surface layer material; adding the preparation raw material of the core layer from the main extruder hopper of the extrusion casting machine as the core layer material;

[0034] (2) extruding the surface layer material through the auxiliary extruder, and extruding the core layer material through the main extruder, then melting and mixing in the extrusion casting machine, and then extruding from the die to obtain a co-extrusion cast piece with a three-layer structure;

[0035] (3) cutting the co-extrusion cast piece to a size of 130mm*130mm, and then stretching and shaping the cast piece in two directions to obtain an ultra-smooth optical film.

[0036] In step (2), the temperature of the auxiliary extruder and the main extruder is set in the range of 270-290℃, but the specific set temperature of the auxiliary extruder and the main extruder can be different. The rotation speed of the main extruder is 170-190rpm, and the rotation speed of the auxiliary extruder is 50-90rpm.

[0037] In step (3), the preheating temperature of the two-way synchronous stretching is 100-120℃, the preheating time is 10-25s, the longitudinal stretching ratio is 3.3-3.8, and the transverse stretching ratio is 3.3-3.8.

[0038] In step (3), the shaping temperature is 200-220℃, and the shaping time is 2-6s.

[0039] The nano-sized powder is easy to agglomerate due to its large intermolecular force, and is not easy to disperse into single particle state, thereby affecting the opening effect of the prepared optical film and the comprehensive performance of the film. At present, when using screw method to prepare opening master batch, higher shearing and mixing action is often required, which is too high for the equipment, and even most of the current equipment cannot achieve the purpose of fully and uniformly dispersing the nano-sized powder into single particles. Therefore, the dispersion problem of the nano-sized powder is still difficult to effectively solve at present.

[0040] In view of the dispersion problem of the nanoscale powder, in the present application, the opening agent powder is modified first, and the modified opening agent powder is used to prepare the opening master batch. Through the modification, the interfacial tension of the nanoscale powder is effectively reduced, the charge barrier is formed, and the steric hindrance between the molecules is increased; at the same time, the intermolecular force is reduced, so that the opening agent powder is easily dispersed and not aggregated, and the dispersion stability is greatly improved. When preparing the opening master batch, the modified opening agent powder is used, and the double screw mixing method is used for preparation, which effectively avoids the secondary aggregation of the opening agent powder, and is beneficial to obtain the opening master batch with uniform distribution of the opening agent powder.

[0041] The optical film prepared by using the opening master batch for super-smooth optical film provided by the present application has good opening property, and the films are not adhered to each other, and are easy to be wound and cut. The surface opening agent of the optical film is uniformly distributed, the roughness of the film is low, the flatness is high, the film is smoother, the surface defects are less, and the optical performance is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a TEM picture of the opening agent powder raw material in Example 1 of the present application;

[0043] Figure 2 is a TEM picture of the modified opening agent powder obtained by treatment in Example 1 of the present application;

[0044] Figure 3 is a polarizing microscope picture of the super-smooth optical film obtained in Example 5 of the present application;

[0045] Figure 4 is a polarizing microscope picture of the super-smooth optical film obtained in Example 6 of the present application;

[0046] Figure 5 is a polarizing microscope picture of the super-smooth optical film obtained in Example 7 of the present application;

[0047] Figure 6 is a 3D surface roughness instrument picture of the super-smooth optical film obtained in Example 5 of the present application;

[0048] Figure 7 is a 3D surface roughness instrument picture of the super-smooth optical film obtained in Example 6 of the present application;

[0049] Figure 8 is a 3D surface roughness instrument picture of the super-smooth optical film obtained in Example 7 of the present application. DETAILED DESCRIPTION

[0050] The technical solutions of the present application will be described in detail below through specific examples. The following examples are intended to further illustrate the content of the present application, and are not a limitation on the scope of protection of the claims of the present application.

[0051] In the following examples, the reagents used are commercially available products.

[0052] Example 1

[0053] The present embodiment provides an opening master batch for super-smooth optical film, and the preparation raw material is composed of the following raw materials in weight fraction:

[0054]

[0055] The optical-grade polyethylene terephthalate is in the form of a pellet, and the intrinsic viscosity is 0.650 dL / g.

[0056] The polyethylene terephthalate for bottles is in the form of a powder, and the intrinsic viscosity is 0.680 dL / g.

[0057] The opening agent powder used in the modified opening agent powder is silicon dioxide, which is in a spherical structure and has an average particle size of 50 nm. The modifier used in the modification is a compound of polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone, which are mixed in a mass ratio of 50:33:17.

[0058] The preparation steps of the modified opening agent powder are as follows: adding silicon dioxide powder and a modifier to an ethanol solvent, stirring for 30 min, then ultrasonic treatment for 60 min to fully disperse the silicon dioxide powder, then heating to 80℃ to evaporate the ethanol, and then grinding and sieving, using a 5-layer sieve with a mesh size of 10000, 20000, 30000, 40000, and 50000 from coarse to fine, and the undersize material is the modified opening agent powder. The mass ratio of ethanol, silicon dioxide powder, and modifier is 93:5:2.

[0059] The TEM images of the opening agent raw material and the modified opening agent powder obtained by treatment are shown in FIGS. 1 and 2, respectively. Figure 1 Figure 2 As shown in FIGS. 1 and 2, the powder of the opening agent raw material has obvious agglomeration, but the dispersion state of the modified opening agent powder is good after modification, and the agglomeration phenomenon is obviously improved.

[0060] The antioxidant used is antioxidant 1010 from BASF.

[0061] The preparation method of the opening master batch for super-smooth optical film uses a double-screw mixing method, including the following steps:

[0062] S1: weighing each raw material according to the weight fraction;

[0063] ​The optical-grade polyethylene terephthalate pellets are added from the main feeding port of the twin-screw mixing device, and the polyethylene terephthalate powder for bottles, modified opening agent powder, and antioxidant are uniformly mixed, and then added from the side feeding port of the twin-screw mixing device;

[0064] S2: The materials are melted and mixed in the twin-screw mixing device, and then extruded from the head of the twin-screw mixing device, cooled and pulled first, and then cut and dried in the cutting and drying system to obtain the ultra-smooth optical film opening master batch.

[0065] The screw temperature of the twin-screw mixing device is 240-260℃, the screw rotation speed is 300 rpm, and the thread combination is a strong shear combination.

[0066] Example 2

[0067] The ultra-smooth optical film opening master batch provided in the embodiment is prepared from raw materials in the following weight proportions:

[0068]

[0069] The raw materials used, i.e., the optical-grade polyethylene terephthalate and the polyethylene terephthalate for bottles, are the same as in Embodiment 1.

[0070] The opening agent powder used in the modified opening agent powder is calcium carbonate, which has a spherical structure and an average particle size of 60 nm. The modifier used in the modification is a compound of polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone, which are mixed in a mass ratio of 50:33:17.

[0071] The preparation steps of the modified opening agent powder are as follows: calcium carbonate powder and a modifier are added to an ethanol solvent, stirred for 30 min, then ultrasonically treated for 60 min to fully disperse the calcium carbonate powder, and then heated to 85℃ to evaporate the ethanol. Then, the mixture is ground and sieved using a 5-layer sieve, with the sieve being arranged from coarse to fine in the order of 10000 mesh, 20000 mesh, 30000 mesh, 40000 mesh, and 50000 mesh. The undersize material is the modified opening agent powder. The mass ratio of ethanol, calcium carbonate powder, and modifier is 93:5:2.

[0072] The antioxidant used is Sumitomo Chemical's antioxidant GA-80.

[0073] The preparation method of the ultra-smooth optical film opening master batch uses a twin-screw mixing method, which includes the following steps:

[0074] S1: Weigh each raw material according to the weight proportions;

[0075] The optical-grade polyethylene terephthalate pellets are added from the main feeding port of the twin-screw mixing device, and the polyethylene terephthalate powder for bottles, modified opening agent powder, and antioxidant are uniformly mixed, and then added from the side feeding port of the twin-screw mixing device;

[0076] S2: The materials are melted and mixed in the twin-screw mixing device, and then extruded from the head of the twin-screw mixing device, cooled and pulled first, and then cut and dried in the cutting and drying system to obtain the ultra-smooth optical film opening master batch.

[0077] The screw temperature of the twin-screw mixing device is 240-260℃, the screw rotation speed is 300rpm, and the thread combination is a strong shear combination.

[0078] Example 3

[0079] The present embodiment provides an ultra-smooth optical film opening master batch, and the preparation raw materials are composed of the following raw materials in weight fractions:

[0080]

[0081] The raw materials used, i.e., the optical-grade polyethylene terephthalate and the polyethylene terephthalate for bottles, are the same as in Embodiment 1.

[0082] The opening agent powder used in the modified opening agent powder is the same as in Embodiment 1, and the modifier used is a compound of polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone, which are mixed in a mass ratio of 40:40:20.

[0083] The preparation steps of the modified opening agent powder are as follows: silica powder and modifier are added to an ethanol solvent, stirred for 30min, and then ultrasonically treated for 60min to fully disperse the silica powder, and then heated to 80℃ to evaporate the ethanol, and then ground and sieved, using a 5-layer sieve screen, with the sieve screens arranged in order from coarse to fine, i.e., 10000 mesh, 20000 mesh, 30000 mesh, 40000 mesh, and 50000 mesh, and the undersize material is the modified opening agent powder. The mass ratio of ethanol, silica powder, and modifier is 93:5:2.

[0084] The antioxidant used is antioxidant 1010 from BASF.

[0085] The preparation method of the ultra-smooth optical film opening master batch uses a twin-screw mixing method, including the following steps:

[0086] S1: The raw materials are weighed according to the weight fractions;

[0087] The optical-grade polyethylene terephthalate pellets are added from the main feeding port of the twin-screw mixing device, and the polyethylene terephthalate powder for bottles, modified opening agent powder, and antioxidant are uniformly mixed, and then added from the side feeding port of the twin-screw mixing device;

[0088] S2: The materials are melted and mixed in the twin-screw mixing device, and then extruded from the head of the twin-screw mixing device, cooled and pulled first, and then cut and dried in the cutting and drying system to obtain the ultra-smooth optical film opening master batch.

[0089] The screw temperature of the twin-screw mixing device is 240-260℃, the screw rotation speed is 300rpm, and the thread combination is a strong shear combination.

[0090] Example 4

[0091] The ultra-smooth optical film opening master batch provided in the embodiment is prepared from raw materials consisting of the following raw materials in parts by weight:

[0092]

[0093] The raw materials used, i.e., the optical-grade polyethylene terephthalate and the polyethylene terephthalate for bottles, are the same as in Embodiment 1.

[0094] The opening agent powder used in the modified opening agent powder is the same as in Embodiment 2, and the modifier used is a compound of polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone, which are mixed in a mass ratio of 40:40:20.

[0095] The preparation steps of the modified opening agent powder are as follows: calcium carbonate powder and a modifier are added to an ethanol solvent, stirred for 30min, and then ultrasonically treated for 60min to disperse the calcium carbonate powder, and then heated to 85℃ to evaporate the ethanol, and then ground and sieved using a 5-layer screen, with the screen being arranged in order from coarse to fine as 10000 mesh, 20000 mesh, 30000 mesh, 40000 mesh, and 50000 mesh, and the undersize material is the modified opening agent powder. The mass ratio of ethanol, calcium carbonate powder, and modifier is 93:10:2.

[0096] The antioxidant used is Sumitomo Chemical's antioxidant GA-80.

[0097] The preparation method of the ultra-smooth optical film opening master batch uses a twin-screw mixing method, which includes the following steps:

[0098] S1: The raw materials are weighed according to the parts by weight;

[0099] The optical-grade polyethylene terephthalate pellets are added from the main feeding port of the twin-screw mixing device, and the polyethylene terephthalate powder for bottles, the modified opening agent powder, and the antioxidant are uniformly mixed, and then added from the side feeding port of the twin-screw mixing device;

[0100] S2: The material is melted and mixed in the twin-screw mixing device, and then extruded from the head of the twin-screw mixing device, first passes through cooling and traction, enters the pelletizing and drying system, is pelletized and dried to obtain the opening master batch for ultra-smooth optical film.

[0101] The screw temperature of the twin-screw mixing device is 240-260°C, the screw rotation speed is 300 rpm, and the thread combination is a strong shear combination.

[0102] The opening master batch prepared in the above Examples 1-4 is subjected to physical property index detection, and the results are shown in Table 1 below.

[0103] Table 1

[0104]

[0105] The optical film is further prepared using the opening master batch prepared in the above Examples 1-4, and the details are shown in the following examples.

[0106] Example 5

[0107] The optical film is prepared using the opening master batch for ultra-smooth optical film provided in Example 1.

[0108] The optical film is an ABA three-layer co-extrusion structure, including a core layer (B) and a surface layer (A) arranged on both sides of the core layer, forming an ABA stacked structure.

[0109] The preparation raw material of the surface layer is composed of film-grade polyethylene terephthalate and the opening master batch for ultra-smooth optical film of Example 1, wherein the mass percentage content of the opening master batch for ultra-smooth optical film in the preparation raw material of the surface layer is 5%. The preparation raw material of the core layer is film-grade polyethylene terephthalate. The total mass of the surface layer accounts for 20% of the total mass of the core layer and the surface layer.

[0110] The preparation method of the optical film includes the following steps:

[0111] (1) The preparation raw material of the surface layer is added from the auxiliary extruder hopper of the extrusion casting machine as the surface layer material; the preparation raw material of the core layer is added from the main extruder hopper of the extrusion casting machine as the core layer material;

[0112] (2) the surface layer material is extruded through the auxiliary extruder, the core layer material is extruded through the main extruder, then melted and mixed in the extrusion caster, and then extruded from the die to obtain a co-extrusion cast sheet with a three-layer structure; wherein the temperature of the auxiliary extruder and the main extruder is set in the range of 270-280℃, the rotating speed of the main extruder is 180rpm, and the rotating speed of the auxiliary extruder is 60rpm;

[0113] (3) the co-extrusion cast sheet is cut into a cast sheet with a size of 130mm*130mm, and then the cast sheet is subjected to bidirectional synchronous stretching and shaping to obtain an ultra-smooth optical film. The preheating temperature of the bidirectional synchronous stretching is 105℃, the preheating time is 20s, the longitudinal stretching ratio is 3.3, and the transverse stretching ratio is 3.3. The shaping temperature is 210℃, and the shaping time is 3s.

[0114] The polarizing microscope picture of the ultra-smooth optical film obtained in this embodiment is shown in Figure 3 The 3D surface roughness instrument picture is shown in Figure 6 .

[0115] Example 6

[0116] This embodiment provides an optical film prepared by using the opening master batch for ultra-smooth optical film provided in Embodiment 2.

[0117] The optical film is an ABA three-layer co-extrusion structure, which comprises a core layer (B) and surface layers (A) arranged on both sides of the core layer, forming a stacked structure of ABA.

[0118] The preparation raw material of the surface layer is composed of film-grade polyethylene terephthalate and the opening master batch for ultra-smooth optical film of Embodiment 2, wherein the mass percentage content of the opening master batch for ultra-smooth optical film in the preparation raw material of the surface layer is 5%. The preparation raw material of the core layer is film-grade polyethylene terephthalate. The total mass of the surface layer accounts for 25% of the total mass of the core layer and the surface layer.

[0119] The preparation method of the optical film comprises the following steps:

[0120] (1) the preparation raw material of the surface layer is added from the auxiliary extruder hopper of the extrusion caster as the surface layer material; and the preparation raw material of the core layer is added from the main extruder hopper of the extrusion caster as the core layer material;

[0121] (2) the surface layer material is extruded through the auxiliary extruder, the core layer material is extruded through the main extruder, then melted and mixed in the extrusion caster, and then extruded from the die to obtain a co-extrusion cast sheet with a three-layer structure; wherein the temperature of the auxiliary extruder and the main extruder is set in the range of 270-280℃, the rotating speed of the main extruder is 180rpm, and the rotating speed of the auxiliary extruder is 60rpm;

[0122] (3) the co-extrusion cast sheet is cut into a size of 130mm*130mm, and the cast sheet is subjected to bidirectional synchronous stretching and setting to obtain the super-smooth optical film. The preheating temperature of the bidirectional synchronous stretching is 105°C, the preheating time is 20s, the longitudinal stretching ratio is 3.3, and the transverse stretching ratio is 3.3. The setting temperature is 210°C, and the setting time is 3s.

[0123] The polarized microscope picture of the super-smooth optical film obtained in the embodiment is shown in Figure 4 The 3D surface roughness instrument picture is shown in Figure 7

[0124] Example 7

[0125] The embodiment provides an optical film prepared by using the opening master batch for super-smooth optical film provided in Embodiment 3.

[0126] The optical film is an ABA three-layer co-extrusion structure, which comprises a core layer (B) and surface layers (A) arranged on both sides of the core layer, forming a layer-by-layer structure of ABA.

[0127] The preparation raw material of the surface layer is composed of film-grade polyethylene terephthalate and the opening master batch for super-smooth optical film in Embodiment 3, wherein the mass percentage content of the opening master batch for super-smooth optical film in the preparation raw material of the surface layer is 7%. The preparation raw material of the core layer is film-grade polyethylene terephthalate. The total mass of the surface layer accounts for 25% of the total mass of the core layer and the surface layer.

[0128] The preparation method of the optical film comprises the following steps:

[0129] (1) the preparation raw material of the surface layer is added from the auxiliary extruder hopper of the extrusion casting machine as the surface layer material; and the preparation raw material of the core layer is added from the main extruder hopper of the extrusion casting machine as the core layer material;

[0130] (2) the surface layer material is extruded through the auxiliary extruder, the core layer material is extruded through the main extruder, and then is melted and mixed in the extrusion casting machine, and then is extruded from the die to obtain a co-extrusion cast sheet with a three-layer structure; wherein the temperature of the auxiliary extruder and the main extruder is set in the range of 270-280°C, the rotating speed of the main extruder is 180rpm, and the rotating speed of the auxiliary extruder is 60rpm;

[0131] (3) the co-extrusion cast sheet is cut into a size of 130mm*130mm, and the cast sheet is subjected to bidirectional synchronous stretching and setting to obtain the super-smooth optical film. The preheating temperature of the bidirectional synchronous stretching is 105°C, the preheating time is 20s, the longitudinal stretching ratio is 3.3, and the transverse stretching ratio is 3.3. The setting temperature is 210°C, and the setting time is 3s.

[0132] ​The polarized microscope picture of the super-smooth optical film obtained in the embodiment is shown in Figure 5 The 3D surface roughness instrument picture is shown in Figure 8 .

[0133] The optical films provided in the above embodiments 5-7 were subjected to performance detection, and the results are shown in Table 2.

[0134] Table 2

[0135]

[0136] As can be seen from Table 2, the optical films provided in the embodiments 5-7 have good opening performance, low haze, high clarity, high light transmittance, excellent optical performance, low roughness, high flatness, and smooth film.

[0137] As can be seen from Table 2, the optical films provided in the embodiments 5-7 have good opening performance, low haze, high clarity, high light transmittance, excellent optical performance, low roughness, high flatness, and smooth film. Figures 3-8 As can be seen from Table 2, the optical films provided in the embodiments 5-7 have good opening performance, low haze, high clarity, high light transmittance, excellent optical performance, low roughness, high flatness, and smooth film. Figure 5 As can be seen from Table 2, the optical films provided in the embodiments 5-7 have good opening performance, low haze, high clarity, high light transmittance, excellent optical performance, low roughness, high flatness, and smooth film.

[0138] The above description is only examples of the present application, and does not limit the patent scope of the present application. Any equivalent transformation or direct or indirect application in other related technical fields based on the content of the present application is included in the patent protection scope of the present application.

Claims

1. An open-face masterbatch for ultra-smooth optical films, characterized in that, The raw materials used in the preparation include the following parts by weight: 67-94 parts of optical grade polyethylene terephthalate 6-30 parts of bottled polyethylene terephthalate Modified opening agent powder, 0.1~2.0 parts Antioxidant 0.1~1.0 parts; The modified opening agent powder used is silicon dioxide and / or calcium carbonate, and the average particle size of the opening agent powder is 30nm~80nm. The modifier used in the modification is a compound of polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone. The polyethylene glycol 400, sodium hexametaphosphate, and polyvinylpyrrolidone are mixed and compounded in a mass ratio of (40~60):(25~40):(15~20). The preparation steps of the modified opening agent powder are as follows: add the opening agent powder and the modifier to the solvent, stir and then sonicate, then evaporate the solvent, and then grind and sieve to obtain the modified opening agent powder; wherein, the mass ratio of the solvent, the opening agent powder and the modifier is (85~97):(2~10):(1~5); ethanol is used as the solvent; The surface roughness of the ultra-smooth optical film is 5nm, 6nm, or 7nm.

2. The open-face masterbatch according to claim 1, characterized in that, The raw materials used in the preparation include the following parts by weight: 70-90.5 parts of optical grade polyethylene terephthalate 9-28 parts of bottled polyethylene terephthalate 0.3~1.5 parts of modified opening agent powder Antioxidant 0.2~0.5 parts.

3. The open-face masterbatch according to claim 1 or 2, characterized in that, The raw materials used in the preparation include the following parts by weight: Optical grade polyethylene terephthalate 80-84.5 parts 15-18 parts of bottled polyethylene terephthalate Modified opening agent powder, 0.5~1.0 parts Antioxidant 0.2~0.5 parts.

4. A method for preparing the open-face masterbatch according to claim 1, characterized in that, The preparation method employs a twin-screw compounding process, including the following steps: S1: Weigh each raw material according to the weight proportions. Add the optical grade polyethylene terephthalate granules from the main feed port of the twin-screw mixing equipment. Mix the bottle-grade polyethylene terephthalate powder, modified opening agent powder, and antioxidant evenly first, and then add them from the side feed port of the twin-screw mixing equipment. S2: The material is melted and mixed in a twin-screw mixer, and then extruded from the die head of the twin-screw mixer. After pelletizing and drying, it yields open-face masterbatch for ultra-smooth optical films. The twin-screw mixing equipment has a screw temperature of 220~260℃, a screw speed of 200~380rpm, and a high-shear screw combination.

5. The application of the open-ended masterbatch for ultra-smooth optical films according to any one of claims 1-3 in the preparation of optical thin films.

6. An optical thin film, characterized in that, The optical thin film has an ABA three-layer co-extruded structure, including a core layer and surface layers disposed on both sides of the core layer; The raw materials for preparing the surface layer include film-grade polyethylene terephthalate and the masterbatch for opening ultra-smooth optical films according to any one of claims 1-3, wherein the mass percentage content of the masterbatch for opening ultra-smooth optical films in the raw materials for preparing the surface layer is 2-10%; The core layer is prepared from film-grade polyethylene terephthalate. The surface layer accounts for 20-30% of the total mass of the core layer and the surface layer.

7. The method for preparing the optical thin film according to claim 6, characterized in that, Including the following steps: (1) The raw material for the preparation of the surface layer is added from the auxiliary extruder hopper of the extrusion casting machine as the surface layer material; the raw material for the preparation of the core layer is added from the main extruder hopper of the extrusion casting machine as the core layer material; (2) The surface material is extruded by an auxiliary extruder, the core material is extruded by a main extruder, and then melted and mixed in an extrusion casting machine, and then extruded from the die head to obtain a co-extruded casting sheet with a three-layer structure; (3) The co-extruded wafer is cut, then stretched and shaped in both directions to obtain an ultra-smooth optical film.

8. The method for preparing an optical thin film according to claim 7, characterized in that, In step (2), the temperatures of the auxiliary extruder and the main extruder are both set to 270~290℃, the speed of the main extruder is 170~190rpm, and the speed of the auxiliary extruder is 50~90rpm. In step (3), the preheating temperature for bidirectional synchronous stretching is 100~120℃, the preheating time is 10~25s, the longitudinal stretching ratio is 3.3~3.8, and the transverse stretching ratio is 3.3~3.

8. In step (3), the setting temperature is 200~220℃ and the setting time is 2~6s.

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