Anti-peep film preparation method, anti-peep film, and anti-peep display panel

Abstract

A method for preparing a privacy film, a privacy film, and a privacy display panel, belonging to the field of display technology, comprises the following steps: Step 01, preparing a melt. Step 02, preparing an unstretched film, wherein the melt obtained in Step 01 is cooled and calendered through three-stage calendering rollers, and finally cooled and wound to prepare an unstretched film. During winding, a layer of tape is applied to both sides of the unstretched film using a tape-applying device. Step 03, preparing a privacy film, wherein the unstretched film obtained in Step 02 is stretched, shrunk, and heat-set to form the desired privacy film. The privacy film thus prepared is then used to prepare a privacy display panel, which exhibits excellent privacy protection.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a method for preparing an anti-peep film, an anti-peep film, and an anti-peep display panel. Background Art

[0002] With the rapid advancement of modern technology, electronic products are increasingly present in people's lives, bringing great convenience and enjoyment. However, this widespread use of electronic products also poses a significant risk of privacy leakage due to the wide viewing angles of electronic screens. This is why privacy filters have emerged. Besides being installed on mobile phones and computers, privacy filters have many other applications, such as in anti-peep display areas like bank ATMs, to protect personal information, passwords, and other content from being leaked.

[0003] Most existing privacy films use a design similar to Venetian blinds. This structure can reduce the range of light reflected from a mobile phone or computer screen, with most of the light returning in the direction of its entry. Therefore, only the user facing the screen can receive this portion of light and see the content on the screen clearly. Onlookers at a certain angle to the screen cannot receive the light reflected from the screen from the side, so even if they look at the screen, they can only see darkness. Figure 1 However, the traditional louver structure makes the film surface flat, complicated to process, and affects the overall thickness and transmittance of the film, which undoubtedly greatly reduces the user experience.

[0004] Other existing technologies, such as Chinese patent CN 112558337A, utilize a dimmer in a display to reduce the angle range of light emitted by a backlight module, thereby reducing the viewing angle of the display. However, the narrow viewing angle of such a display panel is not ideal, and the display structure is complex, which greatly increases power consumption and production costs.

[0005] Secondly, when the optical film is biaxially stretched, the clamping components in the stretching zone clamp and stretch the two sides of the optical film, which can easily cause damage to the two sides of the optical film or cause uncontrollable tensile deformation of the optical film at the clamping position. In order to ensure the quality of the optical film, the clamping parts on both sides of the optical film need to be cut off after production is completed, which results in partial material waste and also affects the production efficiency of the optical film. Summary of the Invention

[0006] The present invention provides a method for preparing a privacy film, a privacy film, and an privacy display panel to address the shortcomings of the above-mentioned prior art. In order to address the shortcomings of the above-mentioned prior art, the light passing through the privacy film is converted from linearly polarized light to elliptically polarized light, thereby reducing the contrast that deviates from the normal direction of the display panel, and even causing the transmittance in the dark state to be greater than the transmittance in the bright state, thereby achieving the purpose of privacy prevention. At the same time, the patent of the present invention also provides a simple and easy-to-operate method for preparing a privacy film.

[0007] In order to achieve the purpose of the present invention, the following technologies are proposed:

[0008] First, the present invention provides a method for preparing a privacy film, comprising the following steps:

[0009] Step 01, preparation of the melt, plasticizing and melting the optically transparent resin through a screw extruder, and then extruding the melt through a T-type die;

[0010] The optically transparent resin is one or more of (meth)acrylic resin, polycarbonate resin, cycloolefin resin, cellulose resin, polyester resin, polyester carbonate resin, polyvinyl acetal resin, olefin resin, polyurethane resin and flexible monomer;

[0011] Step 02, preparation of an unstretched film, cooling and rolling the melt obtained in step 01 through three-stage calendering rollers, and finally cooling and winding to prepare an unstretched film;

[0012] Wherein, during winding, a layer of tape is pasted on both sides of the unstretched film by a tape pasting device;

[0013] Step 03, preparation of the privacy film, the unstretched film obtained in step 02 is prepared into the desired privacy film by stretching, shrinking and heat setting.

[0014] Furthermore, the forming temperature of the unstretched film in step 02 is 120° C. to 350° C.;

[0015] The thickness of the unstretched film is 40 μm-250 μm.

[0016] Furthermore, when preparing the privacy film in step 03:

[0017] When stretching, the stretching temperature is Tg+30°C, where Tg is the glass transition temperature.

[0018] The longitudinal and transverse stretching ratios are 1.3 to 3.3 times, respectively.

[0019] Furthermore, when preparing the shrinkage of the privacy film in step 03:

[0020] At the beginning of the contraction zone, i.e., the end of the stretching zone, the left and right clamping members on both sides of the film move at a spacing of P1. When the film enters the contraction zone, the left and right clamping members on both sides of the film move at a spacing of P2.

[0021] The length of P2 is smaller than that of P1.

[0022] Furthermore, the pitch variation rate of the clamping components is 0.7 to 0.999, and the calculation formula of the pitch variation rate of the clamping components is P2 / P1;

[0023] The time for the spacing of the clamping parts to decrease from P1 to P2 is 3s~10s;

[0024] The size retention rate during shrinkage is 80% to 98%.

[0025] Furthermore, the tape pasting device comprises a pair of pasting mechanisms, each of which is provided with a placement mechanism at one end;

[0026] The sticking mechanism comprises a side plate, wherein the two ends of the side plate are respectively penetrated by a pair of plugging plates, the inner end of the plugging plate is provided with a limiting strip, the inner side of the limiting strip is provided with a V-shaped groove, a middle guide plate is provided between the plugging plates, a pair of sliding sleeves are provided on the middle guide plate for sliding movement, a screw sleeve is provided on the sliding sleeve, an inner top screw rod is provided between the plugging plates, the threads at both ends of the inner top screw rod are rotated in opposite directions, the two ends of the inner top screw rod are respectively provided with a rotating head, the screw sleeve is screwed on the inner top screw rod, the outer wall of the sliding sleeve is provided with an inner top plate, the inner top plate is provided with an inclined hole, and there is an angle between the length direction of the inclined hole and the length direction of the middle guide plate, a middle rod is penetrated in the inclined hole, and a rotating seat is provided at each end of the middle rod, which is installed on the side plate, one of the plugging plates is installed with an end concave piece, and a limiting rod is rotatably provided on the end concave piece, the outer periphery of the limiting rod is provided with an annular groove, the circumferential side of the annular groove is tangent to the groove bottom of the V-shaped groove, and a plurality of sticking components are provided on the side plate;

[0027] The outer end of the concave rotating seat is provided with a concave rotatable seat, and the outer end of the concave rotating seat is provided with a rubber ring. The other end of the concave rotating seat is provided with a connecting convex plate, and the other end of the connecting convex plate is hinged to the lower concave recess, and the length of the connecting plate is longer than the length of the connecting convex plate.

[0028] The placement mechanism includes a disk body installed at one end of the side plate, a rotating shaft is coaxially provided on the disk body, an upper disk is provided at the upper end of the rotating shaft, a lower disk is provided at the lower end of the rotating shaft, three rotating rods are provided on the lower disk in a circular array, a tapered rod is provided at the lower end of the rotating rod, the lower end of the tapered rod is a small end, a fixed screw is provided at the lower end of the tapered rod, a threaded sleeve is screwed on the fixed screw, a tightening sleeve is provided at the upper end of the threaded sleeve for rotation, a notch is provided on the tightening sleeve, and the inner wall of the tightening sleeve is a tapered structure;

[0029] The upper plate is provided with a rotating ring, and the outer circumference of the rotating ring is provided with three locking protrusions in a circular array. A rotating pin is provided on the disk body, and a pair of rotating support plates are rotatably provided on the rotating pin, and the rotating support plates are symmetrical with each other. The other end of the rotating support plate is provided with a locking outer plate, and the inner side of the locking outer plate is provided with a locking block, and the inner side of one of the locking blocks is provided with a slot, and one of the locking protrusions is passed through the slot, and the other end of the locking outer plate is respectively rotatably provided with a folding plate, and a spring is provided between the folding plates, and the other end of one of the locking outer plates is rotatably provided with a first connecting plate, and the other end of the other locking outer plate is rotatably provided with a second connecting plate. The length of the first connecting plate is shorter than the length of the second connecting plate, and a through pin is provided on the disk body, and a three-pronged plate is rotatably provided on the through pin, and the first convex plate on the three-pronged plate is hinged to the other end of the first connecting plate, and the second convex plate on the three-pronged plate is hinged to the other end of the second connecting plate, and the outer end of the third convex plate on the three-pronged plate is provided with a handle rod.

[0030] Secondly, the present invention provides a privacy film, which is prepared by a privacy film preparation method:

[0031] The in-plane phase difference Re of the privacy film within the visible light wavelength range expressed in Formula 1 is 0 to 30 nm;

[0032] Within the visible light wavelength range expressed by formula 2, the vertical in-plane phase difference Rth of the privacy film is 220nm to 580nm;

[0033] The thickness of the privacy film is 10μm to 200μm;

[0034] Formula 1: Re = (Nx - Ny) × d

[0035] Formula 2: Rth = [Nx - (Nx + Ny) / 2] × d

[0036] Wherein, Nx, Ny, and Nz represent the refractive index of the film in the x, y, and z directions, respectively, and d is the thickness of the anti-peep film.

[0037] Furthermore, the in-plane phase difference Re = 0 ~ 15nm;

[0038] The vertical in-plane phase difference Rth = 440 ± 10nm;

[0039] The thickness d of the privacy film is 30μm to 60μm;

[0040] Finally, the present invention provides an anti-peeping display panel, comprising the above-mentioned anti-peeping film, a TN LCD layer, and a polarizer layer;

[0041] The number of privacy films is at least one layer;

[0042] The TN LCD layer is located on the inner side of the privacy film;

[0043] The number of polarizer layers is a pair;

[0044] The polarizer layer is located on the outside of the privacy film or TN LCD layer.

[0045] Furthermore, when the privacy film is a single layer, the privacy film is disposed on the upper side of the TN LCD layer;

[0046] When the privacy film is two-layer, the TN LCD layer is located between the two layers of privacy film, and the polarizer layer is located on the outside of the privacy film;

[0047] The thickness of the TN LCD layer is 400nm~500nm.

[0048] The advantages of the above technical solution are:

[0049] The present invention converts linearly polarized light into elliptically polarized light when passing through the privacy film, thereby reducing the contrast in the direction deviating from the normal line of the display panel, and even causing the transmittance in the dark state to be greater than the transmittance in the bright state, thereby achieving the purpose of privacy protection. The present invention also provides a simple and easy-to-operate method for preparing privacy film. Secondly, the present invention adheres stretchable tape to both sides of the optical film before stretching it, and the provision of the tape prevents pinching of the optical film, while also significantly improving the production efficiency of the optical film. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0051] Figure 1 A three-dimensional structural diagram of an existing anti-peeping display panel is shown.

[0052] Figure 2 A front view of a conventional anti-peeping display panel is shown.

[0053] Figure 3 The structure diagram of the display panel without the privacy mask is shown.

[0054] Figure 4 The structure of an anti-peeping display panel with a single-layer anti-peeping film is shown.

[0055] Figure 5The structure of the anti-peeping display panel with a double-layer anti-peeping film is shown.

[0056] Figure 6 The isocontrast curve diagram of Example 3 is shown.

[0057] Figure 7 The isocontrast curve diagram of Example 4 is shown, and an anti-peep phase difference film with Re=10nm and Rth=220nm is used.

[0058] Figure 8 The isocontrast curve diagram of Example 4 is shown, and an anti-peep phase difference film with Re=8nm and Rth=440nm is used.

[0059] Figure 9 The isocontrast curve diagram of Example 5 is shown, and an anti-peep phase difference film with Re=10nm and Rth=220nm is used.

[0060] Figure 10 The isocontrast curve diagram of Example 5 is shown, and an anti-peep phase difference film with Re=8nm and Rth=440nm is used.

[0061] Figure 11 The diagram of the measurement angle is shown in Figure 1. θ is the angle between the projection of the observation direction on the TN-LCD panel and the horizontal direction of the long side of the panel; ψ is the angle between the observation direction and the normal direction of the TN-LCD panel.

[0062] Figure 12 A three-dimensional structural diagram of a tape sticking device is shown.

[0063] Figure 13 The figure shows a three-dimensional structural diagram of the first part of the sticking mechanism in the tape sticking device.

[0064] Figure 14 The figure shows the three-dimensional structure of the second part of the sticking mechanism in the tape sticking device.

[0065] Figure 15 Shows a three-dimensional structural diagram of the connected round rods.

[0066] Figure 16 A three-dimensional structural diagram of the placement mechanism from a first perspective is shown.

[0067] Figure 17 Shown is a three-dimensional structural diagram of the upper part of the placement mechanism.

[0068] Figure 18 A three-dimensional structural diagram of the placement mechanism from a second viewing angle is shown.

[0069] Figure 19 Shown Figure 18 A is shown in the enlarged view.

[0070] Description of reference numerals:

[0071] Upper PE protective film layer-10, AG hardened layer-11, upper PET layer-12, anti-peeping structure layer-13, lower PET layer-14, lower PE protective film layer-15, louver structure-16, first upper polarizer layer-20, first anti-peeping phase film layer-21, first TN LCD layer-22, first lower polarizer layer-23, upper polarizer layer-30, second upper anti-peeping phase film layer-31, second TN LCD layer 32, second lower privacy film layer 33, second lower polarizer layer 34, third upper polarizer layer 40, third TNLCD layer 41, third lower polarizer layer 42, pasting mechanism 1, placement mechanism 2, side panel 100, inserting plate 101, limiting strip 102, V-groove 103, middle guide plate 104, sliding sleeve 105, screw sleeve 106, inner top screw 107, inner top plate 108, inclined hole 109, middle rod 110, rotating seat 111, end concave member 112, limiting rod 113, rotating inner seat 114, adjusting screw 115, rotating cap 116, adjusting seat 117, guide vertical plate 118, T-groove 119, vertical hole 120, inner column 121, inner plate 122, connecting rod 123, connecting round rod 124, upper recess 125, connecting rotating plate 126, concave rotating seat 127, pasting wheel 128, connecting convex plate 129, lower recess 130, disk body 200, lower disk 201, rotating rod 202, tapered rod 203, fixed screw rod 204, threaded sleeve 205, tightening sleeve 206, notch 207, upper disk 208, rotating ring 209, locking protrusion 210, rotating pin 211, rotating support plate 212, locking outer plate 213, locking block 214, folding plate 216, spring 217, first connecting plate 218, second connecting plate 219, second convex plate 220, first convex plate 221, third convex plate 222, handle bar 223. DETAILED DESCRIPTION

[0072] Example 1

[0073] like Figure 1 and Figure 2As shown, an anti-peeping display panel comprises, from top to bottom, an upper PE protective film layer 10, an AG hardening layer 11, an upper PET layer 12, an anti-peeping structure layer 13, a lower PET layer 14 and a lower PE protective film layer 15. Among them, a plurality of louver structures 16 are provided on the anti-peeping structure layer 13. This anti-peeping film utilizes the grating principle. Through the multiple louver structures on the anti-peeping structure layer 13, when the observer looks at the screen from a straight viewing angle, the light can be completely transmitted along the straight viewing direction. At this time, the visibility of the screen is the best. As the viewing angle tilts, the light transmittance gradually decreases due to partial obstruction. At this time, the visibility of the screen also gradually decreases. When the viewing angle is further tilted, especially when it exceeds 30°, the light is completely blocked by the louver structure, and the light transmittance is reduced to 0. At this time, the screen we observe is pitch black, because a better anti-peeping effect is achieved in the direction away from the straight viewing angle. However, the structure of this privacy film is relatively complex, and the presence of the louver structure 16 will make the surface flatness of the film poor. At the same time, it needs to be prepared by multi-layer lamination, so its processing is cumbersome. At the same time, the presence of the louver structure 16 will cause the thickness of the entire film to increase, and the light transmittance is also low.

[0074] Example 2

[0075] A privacy film having a positive birefringence characteristic, namely, Nz>Nx=Ny, wherein within the visible light wavelength range (380nm to 780nm), the in-plane phase difference Re represented by formula (1) is 0 to 30nm, preferably 0 to 15nm. The vertical in-plane phase difference Rth represented by formula (2) is greater than the phase delay Δn2d2 of the liquid crystal layer of a TN-type liquid crystal display, where Δn2 is the extraordinary light refractive index n of the liquid crystal display. e With ordinary light refractive index n o The difference between them is d2, which is the thickness of the liquid crystal layer of the liquid crystal display, which is between 200nm and 1000nm. In addition, the anti-peep film also satisfies Nz> (Nx+Ny) / 2, and is a positive C plate.

[0076] Re = (Nx - Ny) × d1 Formula (1)

[0077] Rth=[Nx-(Nx+Ny) / 2]×d1 Formula (2)

[0078] Among them, x, y, and z are three-dimensional coordinates, the symbol "x" represents the axis along the molecular chain orientation direction in the film plane, "y" represents the axis perpendicular to the x-axis on the plane, and "z" represents the axis perpendicular to the x-axis and y-axis in the thickness direction (normal direction).

[0079] Symbol N x represents the refractive index along the x-axis.

[0080] Symbol N yRepresents the refractive index along the y-axis, which is the refractive index along the film plane and "N x "The refractive index in the direction perpendicular to the direction.

[0081] Symbol N z represents the refractive index along the z-axis, which is the refractive index along the thickness direction.

[0082] In the above formula, Nx, Ny, and Nz represent the refractive indices of the retardation film in the x, y, and z directions, respectively.

[0083] d1 is the thickness of the privacy film, and its subscript is mainly used to distinguish it from the thickness d2 of the liquid crystal layer of the liquid crystal display.

[0084] Re(λ) is the in-plane retardation of a film measured at 25°C with light of wavelength λ nm. Re is obtained using the following expression (Equation 1): Re = (Nx - Ny) × d1, where d1 represents the thickness of the layer (film).

[0085] Rth (λ) is the retardation along the film thickness measured at 25°C with light of wavelength λ nm. Rth is obtained by the following expression (Equation 2): Rth = [Nx - (Nx + Ny) / 2] × d1, where d1 represents the thickness of the layer (film).

[0086] In order to achieve the anti-peeping effect in this embodiment, the thickness of the anti-peeping phase difference film is set to 10μm~200μm, of course, it is preferably 20μm~100μm, and further preferably 30μm~60μm. The thickness accuracy of the anti-peeping film is ±5%, and it can be more accurately controlled at ±2%. The accuracy here refers to the ratio of the difference between the maximum or minimum value and the average value within the variation range when measuring the thickness of each position of the film to the average value. The calculation formula is thickness accuracy [%] = [maximum or minimum value of thickness - average value] / average value × 100

[0087] By combining the thickness of the privacy film with Equations 1 and 2, we can conclude that the privacy film used in this embodiment has an Re value of less than 30 μm, preferably less than 15 μm, and an Rth value of 220 nm to 580 nm, preferably 440 ± 10 nm. The following table shows the performance test results of the privacy film.

[0088] Table 1 Test data of privacy films with different Rth values

[0089]

[0090] As can be seen from the table, despite the change in Rth values, the privacy film's transmittance, haze, and UV resistance at a wavelength of 380nm all demonstrate excellent performance. The films with Rths of 220nm and 440nm exhibit essentially identical tensile strengths and excellent toughness, while the film with an Rth of 220nm and an R0 of 55 exhibits poor toughness. The film with an Rth of 440nm exhibits superior elongation at break and folding times, demonstrating that the film with an Rth of 440nm exhibits excellent softness and elasticity, while the other two films exhibit slightly less performance.

[0091] Example 3

[0092] like Figure 3 As shown, a display panel includes, from top to bottom, a third upper polarizer layer 40, a third TN LCD layer 41, and a third lower polarizer layer 42. This embodiment is to compare the privacy protection effect before and after using the privacy film. Figure 6 As shown in the figure, it is a contrast curve diagram of the display panel. It is not difficult to find from the figure that the contrast is relatively high at each viewing angle. Such a viewing angle range easily exposes the user's information and does not utilize privacy protection.

[0093] Example 4

[0094] like Figure 4 As shown, an anti-peeping display panel comprises, from top to bottom, a first upper polarizer layer 20, a first anti-peeping phase film layer 21, a first TN LCD layer 22, and a first lower polarizer layer 23. The first anti-peeping phase film layer 21 is the anti-peeping film proposed in Example 2.

[0095] The liquid crystal unit, i.e., the above-mentioned TN LCD layer, is a well-known structure including a pair of substrates, and a liquid crystal layer configured between the pair of substrates as a display medium is a nematic liquid crystal. The nematic liquid crystal is in a twisted alignment in the absence of an electric field, wherein the twisted alignment means that the liquid crystal molecules are aligned basically parallel to the surfaces of the two substrates and the electrodes are arranged on the two substrates. The direction of the electric field is perpendicular to the basic surface direction, and the alignment direction of the liquid crystal molecules can be twisted 90° between the substrates. In order to achieve the anti-peeping effect of the privacy film, the vertical in-plane phase difference Rth of the privacy film is preferably satisfied with the positive birefringence characteristic, i.e., Nz>Nx=Ny, and is greater than the phase delay Δn2d2 of the liquid crystal layer of the TN type liquid crystal display. In this way, the light emitted by the backlight source is converted into linearly polarized light after passing through the lower polarizer. When the linearly polarized light deviates from the vertical direction and is incident on the liquid crystal layer, due to the birefringence characteristics of the liquid crystal, ordinary light and extraordinary light are generated. The phase difference between the two is proportional to the optical path difference Δn1d1, where Δn1 is the extraordinary light refractive index n of the privacy film. e With ordinary light refractive index n oThe difference between the incident polarized light and the normal direction is that the incident polarized light becomes elliptically polarized light after passing through the liquid crystal layer with birefringence, which cannot be completely absorbed by the upper polarizer, resulting in a decrease in the contrast of the light emitted from the upper polarizer. The farther it deviates from the normal direction, the more serious the contrast decreases. Figure 11 As shown, when viewing the display from a normal viewing angle, contrast remains essentially unchanged. However, as the viewing direction deviates from the normal to the display's outgoing light, that is, as the angle θ between the viewing direction and the normal to the TN-LCD panel increases, contrast uniformity gradually decreases at all viewing angles. The greater the angle, the more severe the contrast reduction. Furthermore, as the angle ψ between the projection of the viewing direction onto the TN-LCD panel and the horizontal direction of the panel increases, this unevenness becomes more pronounced, resulting in a more pronounced contrast reduction, to the point where the transmittance in the dark state exceeds that in the bright state, thus achieving the desired privacy protection effect.

[0096] The present invention uses an optical measurement system (DMS) to measure the contrast of the display panel proposed in this embodiment at various viewing angles, and obtains the following: Figure 7 and Figure 8 In order to test the anti-peeping effect of the first anti-peeping phase film layer 21 under different vertical in-plane phase differences Rth under the condition of similar in-plane phase difference Re, two sets of measurements were conducted. Figure 7 The isocontrast curve shown in the figure is the anti-peep phase difference film with Re=10nm, Rth=220nm. Figure 8 The isocontrast curves shown in the figure are obtained by using a privacy retardation film with Re=8nm, Rth=440nm. Figure 7 and Figure 8 By comparison, it is not difficult to find that when using a layer of anti-peep film, as the angle away from the normal viewing angle increases (the value of θ increases), Figure 5 Compared with the 30°-60° angle, the contrast ratio of the display panel decreases significantly, especially when θ is in the range of 30°-60°. The contrast ratio of the display panel decreases most significantly, and even decreases to 0 when φ is 30°, 60°, 120°, 150°, 210°, 240°, 300°, and 330°, which means that the visibility of the display panel is 0 at these angles, which has a very good anti-peeping effect. In addition, when Re does not change much, Rth increases, and the contrast ratio decreases significantly. Figure 7 and Figure 8We can see that the contrast ratio at the normal viewing angle decreases from 60:1 to 48:1. This shows that the increase in Rth should not be too large, otherwise the panel's visibility at the normal viewing angle will be lost. This is because the privacy film prepared by the present invention uses biaxial stretching technology, which can ensure that the Nx and Ny values ​​are similar, thereby obtaining a smaller in-plane phase difference value and a relatively larger phase value in the thickness direction of the privacy film. At this time, when light is emitted from the backlight module, it is converted into linearly polarized light by the lower polarizer and then converted into elliptically polarized light by the liquid crystal cell. After the elliptically polarized light is compensated by the privacy film of the present invention, the ratio of the major and minor axes of the elliptically polarized light increases, and the elliptical properties are enhanced. Therefore, light in the direction away from the normal viewing angle is absorbed by the upper polarizer and appears dark, thereby achieving a good privacy protection effect.

[0097] Example 5

[0098] like Figure 5 As shown, an anti-peeping display panel includes, from top to bottom, an upper polarizer layer 30, a second upper anti-peeping phase film layer 31, a second TN LCD layer 32, a second lower anti-peeping phase film layer 33, and a second lower polarizer layer 34. The contrast of the display panel proposed in this embodiment at various viewing angles was measured using an optical measurement system (DMS), and the results were as follows: Figure 9 and Figure 10 The isocontrast curves are shown. Figure 9 The isocontrast curve shown in the figure is a double-layer anti-peep phase difference film with Re=10nm and Rth=220nm. Figure 10 The iso-contrast curves shown in the figure are for a double-layer privacy film with Re=8nm and Rth=440nm. Comparing the aforementioned iso-contrast curves, it can be seen that the display panel with a double-layer privacy film structure has a significant decrease in contrast away from the normal viewing angle, and the decrease is more severe than that of a single-layer structure. Furthermore, when Rth is large, the contrast decrease at the normal viewing angle is more pronounced. This is because when privacy films are applied to both sides of the liquid crystal cell, the backlight light is converted to elliptically polarized light when passing through the lower layer of privacy film, resulting in a certain degree of light transmittance loss. The light transmittance loss is further severe when passing through the liquid crystal cell and the upper polarizer. The larger the Rth value, the greater the ratio of the major and minor axes of the elliptically polarized light, which further reduces the contrast at the normal viewing angle.

[0099] Example 6

[0100] A method for preparing a privacy film comprises the following steps:

[0101] Step 01, preparation of the melt, plasticizing and melting the optically transparent resin through a screw extruder, and then extruding the melt through a T-type die;

[0102] The optically transparent resin is one or more of (meth)acrylic resin, polycarbonate resin, cycloolefin resin, cellulose resin, polyester resin, polyester carbonate resin, polyvinyl acetal resin, olefin resin, polyurethane resin and flexible monomer.

[0103] The (meth)acrylic resin is selected from one or more of polymethyl methacrylate, poly(meth)acrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylate copolymer, methyl methacrylate-acrylate-(meth)acrylic acid copolymer, and (meth)acrylate-styrene copolymer (MS resin). If methyl methacrylate is used, the number of carbon atoms of acrylic acid in methyl methacrylate is 4 to 8.

[0104] The above-mentioned cycloolefin resin is prepared by ring-opening polymerization of norbornene monomer and comonomer, and hydrogen needs to be added during preparation. Specifically, the norbornene monomer can be selected from one or more monomers selected from bicyclo[2.2.1]hept-2-ene, tricyclo[4,3,0,12,5]-3-decene, tricyclo[4,4,0,12,5]-3-undecene, 7-methyltricyclo[4,4,0,12,5]-3-undecene, 5-methylbicyclo[2,2,1]hept-2-ene, 1-methylbicyclo[2,2,1]hept-2-ene, 7-methylbicyclo[2,2,1]hept-2-ene, 5-ethylbicyclo[2,2,1]hept-2-ene, and the comonomer can be cyclobutene, cyclopentene, cyclooctene, dicyclopentadiene, and prepared by ring-opening polymerization and hydrogenation.

[0105] The above-mentioned polycarbonate resin can use any appropriate polycarbonate resin. Taking into account the optical properties, mechanical properties and high temperature resistance of the resin, it is preferred that the main chain of the polycarbonate molecule contains a cyclic structure, that is, a cyclic monomer is used for polymerization, such as: 4,4'-isopropylidene diphenol, 4,4'-(1-methylethylene)bis(2-methylphenol), 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 4,4'-(1-methylethylene)bis(2-methylphenol), 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, isosorbide (ISB), isomannide, isoidide, etc. One or more thereof.

[0106] In order to ensure good mechanical processing properties of polycarbonate, its copolymer should also include a flexible monomer. The general structure of the flexible monomer is as follows:

[0107]

[0108] Formula 1

[0109] In general formula 1, R1 and R2 represent an alkyl group with 2-4 carbon atoms or an alkyl group with a substituent, and the substituent may be a sulfur atom, a silicon atom, a halogen atom, a nitro group, etc. The content of the flexible monomer represented by general formula 1 in the resin is preferably greater than 5% by mass and less than 30% by mass, and more preferably greater than 10% by mass and less than 15% by mass. If the content of the structural monomer represented by general formula (1) is too low, the heat resistance of the entire resin becomes too high, and the mechanical properties and melt processability deteriorate. If the content of the structural monomer represented by general formula (1) is too high, there is a tendency to cause insufficient heat resistance. When the content of the flexible monomer is within the above range, the glass transition temperature of the polycarbonate resin is 120°C~170°C, and the thermal decomposition temperature is 350°C~400°C, which has a wide processing window and is conducive to processing and molding.

[0110] Step 02, the preparation of an unstretched film, involves cooling and rolling the melt obtained in step 01 through three stages of calendering rollers, followed by cooling and winding to produce an unstretched film. During winding, a layer of tape is applied to both sides of the unstretched film using a tape-applying device.

[0111] During molding, the molding temperature is 120°C to 350°C, and more preferably 130°C to 300°C. To ensure the subsequent preparation of the privacy film, the thickness of the unstretched film is limited to 40μm-250μm. When the thickness exceeds 250μm, it is easy to cause uneven thickness. When the thickness is less than 40μm, it is easy to cause stretching fracture during the subsequent stretching process. The preferred thickness can be 80μm-130μm, and more preferably 100μm-120μm.

[0112] Among them, such as Figure 12 As shown, the tape applying device comprises a pair of applying mechanisms 1, each of which is provided with a placement mechanism 2 at one end. The device is installed after the original film is cooled and before it is wound. During the application process, six tapes are fixed to the placement mechanism 2. When the original film is wound and transported forward, the tapes are applied to both sides of the original film by the applying mechanism 1. The original film here is the unstretched film mentioned above.

[0113] like Figures 13 to 15As shown, the pasting mechanism 1 includes a side plate 100, and a pair of plug plates 101 are respectively passed through the two ends of the side plate 100. The inner end of the plug plate 101 is provided with a limiting strip 102, and the inner side of the limiting strip 102 is provided with a V-shaped groove 103. A middle guide plate 104 is provided between the plug plates 101, and a pair of sliding sleeves 105 are slidably provided on the middle guide plate 104. A screw sleeve 106 is provided on the sliding sleeve 105. An inner top screw rod 107 is provided between the plug plates 101. The threads at both ends of the inner top screw rod 107 are rotated in opposite directions. The two ends of the inner top screw rod 107 are respectively provided with a rotating head, and the screw sleeve 106 is screwed to the inner top screw rod 1 07, the outer wall of the sliding sleeve 105 is provided with an inner top plate 108, and the inner top plate 108 is provided with an oblique hole 109. There is an angle between the length direction of the oblique hole 109 and the length direction of the middle guide plate 104. A middle rod 110 is passed through the oblique hole 109, and a rotating seat 111 is provided at both ends of the middle rod 110. The rotating seat 111 is installed on the side plate 100. An end concave part 112 is installed on one of the plug plates 101, and a limit rod 113 is rotatably provided on the end concave part 112. The outer periphery of the limit rod 113 is provided with an annular groove. The setting of the limit rod 113 and the annular groove plays a role in limiting the adhesive tape. The circumferential side of the annular groove is tangent to the bottom of the V-shaped groove 103. The setting of the V-shaped groove 103 plays a role in limiting the adhesive tape. At the same time, when the original film is transported forward, both sides of the original film are passed through the V-shaped groove 103, so that the adhesive tape is partially adhered to the side wall of the original film. The V-shaped groove 103 is set to be adjustable, so that it can be adaptively adjusted according to the width of the original film and constrain the original film. A plurality of adhesive components are provided on the side plate 100.

[0114] like Figure 14As shown, the pasting component includes a rotating inner seat 114 installed on the outer wall of the side plate 100, an adjusting screw rod 115 is rotatably provided on the rotating inner seat 114, a rotating cap 116 is provided on the outer end of the adjusting screw rod 115, an adjusting seat 117 is screwed on the adjusting screw rod 115, and a guide vertical plate 118 is provided at the upper and lower ends of the adjusting seat 117, a T-shaped slot 119 is provided on the guide vertical plate 118, a vertical hole 120 is provided at the bottom of the T-shaped slot 119, an inner column 121 is passed through the vertical hole 120, an inner side end of the inner column 121 is provided with an inner disk 122, the inner disk 122 is located on the inner side of the T-shaped slot 119, a connecting rod 123 is provided on the inner disk 122, the connecting rod 123 extends out of the T-shaped slot 119, a connecting round rod 124 is provided at the outer end of the connecting rod 123, and the inner side of the connecting round rod 124 is provided. An upper recess 125 is provided at the side end, and a connecting rotating plate 126 is hingedly connected to the upper recess 125. The inner end of the connecting rotating plate 126 is provided with a concave rotating seat 127. A pasting wheel 128 is rotatably installed in the concave rotating seat 127. The outer wall of the pasting wheel 128 is provided with a rubber ring. The rubber ring can prevent the pasting wheel from scratching or otherwise damaging the original film during tape application. The provision of multiple pairs of adjustable pasting wheels 128 facilitates support for the back side of the tape. At the same time, the tape can be gradually applied to the original film through a gradual adjustment method. On the one hand, this can prevent the formation of cavitations between the tape and the original film after application, thereby affecting the stretching operation of the original film. On the other hand, during the pasting process, the tape is prevented from forming pasting wrinkles, thereby preventing the stretching operation of the original film from being affected. It is also worth noting that the adjustment of each pair of pasting wheels 128 adopts a synchronous adjustment method. The other end of the concave rotating seat 127 is provided with a connecting protruding plate 129 , and the other end of the connecting protruding plate 129 is hinged with a lower recessed seat 130 . The length of the connecting rotating plate 126 is longer than that of the connecting protruding plate 129 .

[0115] The device used in this embodiment operates as follows for tape application: an operator rotates the rotating cap 116, which in turn drives the adjusting screw 115 to rotate. The rotation of the adjusting screw 115 drives the adjusting seat 117 to move. The movement of the adjusting seat 117 causes the connecting rod 124 to move along its axial direction. The movement of the connecting rod 124 drives the concave rotating seat 127 to rotate around the inner end of the lower recess 130. The rotation of the concave rotating seat 127 changes the inclination angle of the application wheels 128, thereby adjusting the inclination angle of each pair of application wheels 128. After adjustment, the angle between each pair of application wheels 128 gradually decreases along the forward direction of the original film, and the application wheels 128 at the end are horizontal, that is, the angle between the application wheels 128 is 0 degrees.

[0116] When adjusting the limiting strip 102 so that the V-shaped groove 103 limits the original film and the adhesive tape, the operator rotates the inner screw rod 107. As the inner screw rod 107 rotates, the screw sleeve 106 moves along its length. When the screw sleeve 106 moves, the middle rod 110 acts on the inner wall of the inclined hole 109, thereby causing the limiting strip 102 to move outward or inward.

[0117] like Figures 16 to 19 As shown, the placement mechanism 2 includes a disk body 200 mounted on one end of the side plate 100, a rotating shaft is coaxially provided on the disk body 200, an upper disk 208 is provided at the upper end of the rotating shaft, a lower disk 201 is provided at the lower end of the rotating shaft, three rotating rods 202 are provided on the lower disk 201 in a circular array, and a tapered rod 203 is provided at the lower end of the rotating rod 202. The lower end of the tapered rod 203 is a small end, and the upper end of the tapered rod 203 can act on the inner wall of the tape. , thereby fixing the tape on the conical rod 203. A fixed screw rod 204 is provided at the lower end of the conical rod 203. A wire sleeve 205 is screwed on the fixed screw rod 204. A tightening sleeve 206 is rotatably provided at the upper end of the wire sleeve 205. A notch 207 is provided on the tightening sleeve 206. The inner wall of the tightening sleeve 206 is a conical structure. When the tightening sleeve moves, it can gradually open, so that its outer wall acts on the tape, thereby positioning the lower end of the tape.

[0118] like Figure 17 As shown, a rotating ring 209 is provided on the upper disk 208, and three positioning protrusions 210 are provided in a circular array on the outer circumference of the rotating ring 209. A rotating pin 211 is provided on the disk body 200. A pair of rotating support plates 212 are rotatably provided on the rotating pin 211. The rotating support plates 212 are symmetrical to each other. A locking outer plate 213 is provided at the other end of the rotating support plate 212. A positioning block 214 is provided on the inner side of the locking outer plate 213. A card slot is provided on the inner side of one of the positioning blocks 214. One of the positioning protrusions 210 is passed through the card slot. A folding plate 216 is rotatably provided at the other end of the locking outer plate 213. A spring 217 is provided between the shaped plates 216, and a first connecting plate 218 is rotatably provided at the other end of one of the locking outer plates 213, and a second connecting plate 219 is rotatably provided at the other end of the other locking outer plate 213. The length of the first connecting plate 218 is shorter than the length of the second connecting plate 219. A through pin is provided on the disk body 200, and a three-pronged plate is rotatably provided on the through pin. The first protruding plate 221 on the three-pronged plate is hinged to the other end of the first connecting plate 218, and the second protruding plate 220 on the three-pronged plate is hinged to the other end of the second connecting plate 219. The outer end of the third protruding plate 222 on the three-pronged plate is provided with a handle rod 223.

[0119] When one roll of tape is used up, the operator first sticks the end of the next roll of tape to the end of the previous roll of tape, and then rotates the three-pronged plate using the handle bar 223. When the three-pronged plate rotates, it acts on the locking outer plate 213 through the second connecting plate 219 and the first connecting plate 218, thereby causing the rotating support plate 212 to open and the spring 217 to be compressed. As the rotating support plate 212 rotates, the locking protrusion 210 is removed from the locking slot. The operator then rotates the new roll of tape to the appropriate position, and after completion, the handle bar 223 is released, and finally the other locking protrusion 210 is inserted into the locking slot.

[0120] Step 03, preparation of the privacy film, the unstretched film obtained in step 02 is prepared into the desired privacy film by stretching, shrinking and heat setting.

[0121] During stretching, the stretching temperature is controlled within the range of Tg + 30°C relative to the glass transition temperature (Tg) of the raw material resin, preferably Tg + 20°C, and more preferably Tg + 15°C. The longitudinal and transverse stretch ratios can each be 1.3x to 3.3x, more preferably 1.5x to 3x, and even more preferably 2x to 3x. This is because if the stretch ratio is too low, the effective range for achieving the desired degree of orientation and orientation angle becomes narrower. If the stretch ratio is too high, the stretched film may break or wrinkle.

[0122] During shrinkage, the film shrinks in the machine direction (MD) by reducing the spacing between the clamping members in the stretching zone within the shrinking zone. In this embodiment, stretching followed by MD shrinkage produces a privacy film with excellent axial accuracy, minimal phase shift, minimal dimensional change, and a slow axis in the oblique direction. Specifically, at the beginning of the shrinking zone (i.e., the end of the stretching zone), the left and right clamping members on either side of the film move at a spacing of P1. During the MD shrinkage process, the spacing between the left and right clamping members is reduced to P2. The ratio of change in the spacing between the clamping members (P2 / P1) is preferably 0.7 to 0.999, more preferably 0.7 to 0.995, and even more preferably 0.8 to 0.99. The time required to reduce the spacing between the clamping members from P1 to P2 ranges from 3 to 10 seconds. This is because a time shorter than 3 seconds can easily disrupt molecular orientation regularity and lead to wrinkles. A time longer than 10 seconds can result in ineffective shrinkage, hindering the release of residual stress generated during stretching, and leading to uneven phase shift. If it is assumed that the distance between two points in the longitudinal direction of the film before shrinkage is L1, then after the shrinkage is completed, the distance between the corresponding two points on the film is L2, and the size retention rate L2 / L1 is preferably 80% to 98%, and more preferably 90% to 95%. When the size retention rate is within the above range, the quality of the anti-peep film can be significantly improved.

[0123] During heat setting, the heat setting temperature is preferably within the range of Tg to (Tg + 10°C), preferably Tg to (Tg + 5°C), relative to the glass transition temperature (Tg) of the resin used for the unstretched film. This is because if the heat setting temperature is too high, the molecular orientation obtained by stretching may become random, potentially significantly reducing the desired retardation. Conversely, if the heat treatment temperature is too low, the regular molecular alignment may be impaired, which may result in changes in optical properties.

[0124] The privacy film obtained in step 03 has a thickness of 10 μm to 200 μm, preferably 20 μm to 100 μm, and more preferably 30 μm to 60 μm.

[0125] The privacy film obtained in step 03 has a thickness accuracy of ±5μm, preferably ±2μm. The thickness accuracy of the privacy film described above represents the ratio of the difference between the maximum or minimum value and the average value within the thickness variation range measured at each location of the film to the average value. The calculation formula is: Thickness Accuracy [%] = [Maximum or Minimum Thickness - Average] Average value × 100.

[0126] The privacy film obtained in step 03 has a Re value of less than 30 μm, preferably less than 15 μm.

[0127] The privacy film obtained in step 03 has an Rth value of 220 nm to 580 nm, and a preferred Rth value of 440 ± 10 nm.

[0128] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It is apparent that various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the present invention. Thus, the present invention is intended to encompass such modifications and variations as long as they fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a privacy film, characterized in that: The steps include: Step 01, preparation of the melt, plasticizing and melting the optically transparent resin through a screw extruder, and then extruding the melt through a T-type die; The optically transparent resin is one or more of (meth)acrylic resin, polycarbonate resin, cycloolefin resin, cellulose resin, polyester resin, polyester carbonate resin, polyvinyl acetal resin, olefin resin, polyurethane resin and flexible monomer; Step 02, preparation of an unstretched film, cooling and rolling the melt obtained in step 01 through three-stage calendering rollers, and finally cooling and winding to prepare an unstretched film; Wherein, during winding, a layer of tape is pasted on both sides of the unstretched film by a tape pasting device; The tape pasting device comprises a pair of pasting mechanisms (1), and a placement mechanism (2) is provided at one end of each pasting mechanism (1); The pasting mechanism (1) includes a side plate (100), and a pair of inserting plates (101) are respectively passed through the two ends of the side plate (100), and the inner end of the inserting plate (101) is provided with a limit strip (102), and the inner side of the limit strip (102) is provided with a V-shaped groove (103). A middle guide plate (104) is provided between the inserting plates (101), and a pair of sliding sleeves (105) are slidably provided on the middle guide plate (104), and a screw sleeve (106) is provided on the sliding sleeve (105). An inner top screw rod (107) is provided between the inserting plates (101), and the threads at the two ends of the inner top screw rod (107) are rotated in opposite directions. The two ends of the inner top screw rod (107) are respectively provided with a rotating head, and the screw sleeve (106) is screwed to the inner top screw rod (107). The outer wall of the movable sleeve (105) is provided with an inner top plate (108), and an inclined hole (109) is opened on the inner top plate (108). An angle is formed between the length direction of the inclined hole (109) and the length direction of the middle guide plate (104). A middle rod (110) is passed through the inclined hole (109), and a rotating seat (111) is provided at both ends of the middle rod (110). The rotating seat (111) is installed on the side plate (100). An end concave member (112) is installed on one of the plug plates (101), and a limiting rod (113) is rotatably provided on the end concave member (112). The outer periphery of the limiting rod (113) is provided with an annular groove, and the peripheral side of the annular groove is tangent to the groove bottom of the V-shaped groove (103). A plurality of adhesive components are provided on the side plate (100); The pasting component includes a rotating inner seat (114) installed on the outer wall of the side plate (100), an adjusting screw rod (115) is rotatably provided on the rotating inner seat (114), a rotating cap (116) is provided on the outer end of the adjusting screw rod (115), an adjusting seat (117) is screwed on the adjusting screw rod (115), and a guide vertical plate (118) is provided at the upper and lower ends of the adjusting seat (117), a T-shaped slot (119) is provided on the guide vertical plate (118), a vertical hole (120) is provided at the bottom of the T-shaped slot (119), an inner column (121) is passed through the vertical hole (120), an inner disc (122) is provided on the inner side of the inner column (121), the inner disc (122) is located on the inner side of the T-shaped slot (119), and a connecting rod (122) is provided on the inner disc (122). A connecting rod (123), a connecting rod (123) extending from a T-shaped groove (119), a connecting round rod (124) provided at an outer end of the connecting rod (123), an upper recess (125) provided at an inner end of the connecting round rod (124), a connecting rotating plate (126) hingedly connected to the upper recess (125), a concave rotating seat (127) provided at an inner end of the connecting rotating plate (126), a pasting wheel (128) rotating inside the concave rotating seat (127), a rubber ring provided on an outer wall of the pasting wheel (128), a connecting convex plate (129) provided at the other end of the concave rotating seat (127), a lower recess (130) hingedly connected to the other end of the connecting convex plate (129), and a length of the connecting rotating plate (126) longer than a length of the connecting convex plate (129); The placement mechanism (2) includes a disk body (200) mounted on one end of the side plate (100), a rotating shaft is coaxially provided on the disk body (200), an upper disk (208) is provided at the upper end of the rotating shaft, a lower disk (201) is provided at the lower end of the rotating shaft, three rotating rods (202) are provided on the lower disk (201) for rotation in a circular array, a tapered rod (203) is provided at the lower end of the rotating rod (202), the lower end of the tapered rod (203) is a small end, a fixed screw rod (204) is provided at the lower end of the tapered rod (203), a threaded sleeve (205) is screwed on the fixed screw rod (204), a top tightening sleeve (206) is provided at the upper end of the threaded sleeve (205), a notch (207) is provided on the top tightening sleeve (206), and the inner wall of the top tightening sleeve (206) is a tapered structure; A rotating ring (209) is provided on the upper disk (208), and three positioning protrusions (210) are provided in a circular array on the outer periphery of the rotating ring (209). A rotating pin (211) is provided on the disk body (200), and a pair of rotating support plates (212) are rotatably provided on the rotating pin (211). The rotating support plates (212) are symmetrical to each other, and a locking outer plate (213) is provided at the other end of the rotating support plate (212). A positioning block (214) is provided on the inner side of the locking outer plate (213), and a slot is provided on the inner side of one of the positioning blocks (214), and one of the positioning protrusions (210) is inserted into the slot. A folding plate (216) is rotatably provided at the other end of the locking outer plate (213). A spring (217) is provided between the folding plates (216), the other end of one of the locking outer plates (213) is rotatably provided with a first connecting plate (218), and the other end of the other locking outer plate (213) is rotatably provided with a second connecting plate (219), the length of the first connecting plate (218) is shorter than the length of the second connecting plate (219), a through pin is provided on the disc body (200), a three-pronged plate is rotatably provided on the through pin, a first protruding plate (221) on the three-pronged plate is hinged to the other end of the first connecting plate (218), a second protruding plate (220) on the three-pronged plate is hinged to the other end of the second connecting plate (219), and a handle rod (223) is provided at the outer end of the third protruding plate (222) on the three-pronged plate; Step 03, preparation of the privacy film, the unstretched film obtained in step 02 is prepared into the desired privacy film by stretching, shrinking and heat setting operations.

2. The method for preparing a privacy film according to claim 1, wherein: When preparing the unstretched film in step 02, the molding temperature is 120° C. to 350° C.; The thickness of the unstretched film is 40 μm-250 μm.

3. The method for preparing a privacy film according to claim 1, wherein: When preparing the privacy film in step 03: During stretching, the stretching temperature is Tg ± 30 °C, where Tg is the glass transition temperature; The longitudinal and transverse stretching ratios are 1.3 to 3.3 times, respectively.

4. The method for preparing a privacy film according to claim 3, wherein: When preparing the shrinkage of the privacy film in step 03: At the beginning of the contraction zone, i.e., the end of the stretching zone, the left and right clamping members on both sides of the film move at a spacing of P1. When the film enters the contraction zone, the left and right clamping members on both sides of the film move at a spacing of P2. The length of P2 is smaller than that of P1.

5. The method for preparing a privacy film according to claim 4, wherein: The pitch change rate of the clamping parts is 0.7 to 0.999, and the calculation formula of the pitch change rate of the clamping parts is P2 / P1; The time for the spacing of the clamping parts to decrease from P1 to P2 is 3s~10s; The size retention rate during shrinkage is 80% to 98%.

6. A privacy film, characterized in that: Prepared by the method for preparing the privacy film according to any one of claims 1 to 5: The in-plane phase difference Re of the privacy film within the visible light wavelength range expressed in Formula 1 is 0 to 30 nm; Within the visible light wavelength range expressed by formula 2, the vertical in-plane phase difference Rth of the privacy film is 220nm to 580nm; The thickness of the privacy film is 10μm to 200μm; Formula 1: Re = (Nx - Ny) × d Formula 2: Rth = [Nx - (Nx + Ny) / 2] × d Wherein, Nx, Ny, and Nz represent the refractive index of the film in the x, y, and z directions, respectively, and d is the thickness of the anti-peep film.

7. The privacy film according to claim 6, characterized in that: In-plane phase difference Re = 0 ~ 15nm; The vertical in-plane phase difference Rth = 440 ± 10nm; The thickness d of the privacy film is 30 μm to 60 μm.

8. An anti-peeping display panel, characterized in that: comprising the privacy film as claimed in any one of claims 6 and 7, a TN LCD layer and a polarizer layer; The number of privacy films is at least one layer; The TN LCD layer is located on the inner side of the privacy film; The number of polarizer layers is a pair; The polarizer layer is located on the outside of the privacy film or TN LCD layer.

9. The anti-peeping display panel according to claim 8, wherein: When the privacy film is a single layer, the privacy film is placed on the upper side of the TN LCD layer; When the privacy film is two-layer, the TN LCD layer is located between the two layers of privacy film, and the polarizer layer is located on the outside of the privacy film; The thickness of the TN LCD layer is 400nm~500nm.

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