A CPP multilayer composite film and a method for preparing the same

Abstract

The application provides a CPP multilayer composite film which comprises, from top to bottom, a diffusion coating layer, a core layer, a first adhesive layer, a first PET substrate layer, a second adhesive layer, a first prism film, a third adhesive layer, a second prism film and a back coating layer, wherein the first adhesive layer is composed of two components of UV adhesive, namely A adhesive and B adhesive, wherein the A adhesive is composed of the following components: acrylic resin, methyl methacrylate, tripropylene glycol diacrylate, alpha-hydroxy ketone and triethyl phosphonoacetate; and the B adhesive is composed of the following components: acrylic resin, diethylene glycol divinyl ether, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, dimethyl sulfoxide and resorcinol monobenzoate. The CPP multilayer composite film provided by the application provides the first adhesive layer which is suitable for face bonding of the core layer and the first PET substrate layer, and the first adhesive layer can be matched with the core layer and the first PET substrate layer, so that the film layer is prevented from being warped after bonding.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite film in a backlight module of a liquid crystal television, in particular to a CPP multi-layer composite film and a preparation method thereof. BACKGROUND

[0002] The liquid crystal itself in a liquid crystal television does not emit light, and a backlight module is used as a backlight source of the liquid crystal display to irradiate the liquid crystal display component to display an image. Before the light in the backlight source reaches the liquid crystal layer, the light is modulated by a polarizer, so that part of the light enters the liquid crystal layer, and the other part of the light is filtered out and not used. In order to improve the utilization rate of the part of the light that is filtered out, a reflective polarizing film (also commonly referred to as a reflective polarizing brightening film, a double brightening film, or a core layer (Core)) for the backlight module is developed in the prior art. The reflective polarizing film passes the light in the backlight source that can be used by the liquid crystal panel, and reflects the other half of the light that cannot be used back to the backlight source for repeated use, thereby greatly improving the overall brightness of the liquid crystal television.

[0003] The prior art commonly refers to a composite film sheet formed by bonding two prism films to each other as a POP composite film sheet (Prismon Prism), a composite film sheet formed by bonding a diffuser film and two prism films as a DPP composite film sheet (Diffuser on Prism and prism), and similarly, a composite film sheet formed by bonding a core layer on two prism films as a CPP composite film sheet (Core on Prism and Prism).

[0004] For example, CN 112630875 A discloses a high-haze POP composite film sheet, which includes a diffuser film, an upper prism film, a lower prism film, and first and second adhesive layers for bonding the three into a whole. The upper prism film and the lower prism film of the prior art each have a plurality of prism structures arranged in parallel, and at least part of the top of the prism structures is integrally formed with a vertically upward extending flange in the shape of a long strip. The prior art forms a vertically upward extending flange on the top of the prism structure of the prism film, so that the flange can penetrate into the adhesive layer, and the top of the prism structure is prevented from entering the adhesive layer, so that the width of the top of the prism structure that is damaged can be controlled by the thickness of the flange, a greater center brightness value can be obtained, and the viewing angle can be improved by cooperating with the diffuser film, and a higher product haze can be obtained. The prior art increases the adhesive layer, which increases the thickness, and due to the difference in surface tension between the adhesive layer and the film sheets on both sides, a large size shrinkage occurs when the adhesive layer is cured in a large size bonding range, and warping deformation is easily caused after the composite.

[0005] To solve the above technical problems, the applicant discloses a DPP composite film and a preparation method thereof in the patent application CN 115963662 A. The DPP composite film comprises a diffusion film, an upper prism film, and a lower prism film. The top of the prism structure on the upper prism film and the lower prism film is formed with a flange. The bottom of the upper prism film and the diffusion film is formed with a groove for inserting the flange. The diffusion film, the upper prism film, and the lower prism film are integrated by the adhesive filled in the groove and the inserted flange. The prior art removes the large-area adhesive layer in the prior art, and locally bonds the inserted flange by the adhesive, which can avoid warping and deformation, reduce material requirements and save a large amount of material cost, greatly increase the structural strength and the firmness of bonding, and can avoid structural fracture and delamination. The above prior art improves the surface bonding to local line contact, reduces the thickness of the adhesive layer, reduces the amount of local glue under the condition of ensuring the firmness of bonding, thereby reducing the stretching amount of the adhesive and avoiding the probability of warping due to bonding.

[0006] However, with the popularity of the trend of light and thin liquid crystal televisions, new films become thinner and thinner. For example, the thickness of the core layer in the CPP composite film is usually only about 30 µm. The thickness cannot provide a flange and a groove with sufficient height, and can only be surface-bonded. In order to avoid warping during large-area bonding, it is necessary to use film materials and adhesives with similar expansion rates as much as possible. However, materials with similar expansion rates do not necessarily meet the needs of the corresponding film in terms of optical performance. It is difficult to find an adhesive with similar expansion rates to the two materials when bonding films with different expansion rates. Therefore, measures need to be taken to avoid warping. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a CPP multi-layer composite film and a preparation method thereof to reduce or avoid the problems mentioned above.

[0008] To solve the above technical problems, the application provides a CPP multilayer composite film, which comprises, from top to bottom, a diffusion coating layer, a core layer, a first adhesive layer, a first PET substrate layer, a second adhesive layer, a first prism film, a third adhesive layer, a second prism film and a back coating layer, wherein the first adhesive layer is composed of two components of UV adhesive, namely A adhesive and B adhesive; the A adhesive is composed of the following components: 30-40 wt% of acrylic resin, 15-30 wt% of methyl methacrylate, 10-20 wt% of tripropylene glycol diacrylate, 1-3 wt% of alpha-hydroxy ketone and 5-10 wt% of triethyl phosphonoacetate, and the sum of the above components is 100 wt%; the B adhesive is composed of the following components: 35-45 wt% of acrylic resin, 20-40 wt% of diethylene glycol divinyl ether, 2-4 wt% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, 5-10 wt% of dimethyl sulfoxide and 3-8 wt% of resorcinol monobenzoate, and the sum of the above components is 100 wt%.

[0009] Preferably, the A adhesive is coated on the lower surface of the core layer, and the B adhesive is sprayed on the upper surface of the first PET substrate layer.

[0010] Preferably, the weight ratio of the A adhesive to the B adhesive is 10:1.

[0011] Preferably, the total thickness of the adhesive layer obtained after curing of the first adhesive layer is 12-18 µm.

[0012] Preferably, the core layer is a multilayer reflective polarizing film, wherein the side of the core layer facing the first PET substrate is a PEN substrate.

[0013] Preferably, the thickness of the core layer is 25-35 µm.

[0014] The application also provides a preparation method of the CPP multilayer composite film, comprising the following steps: firstly, using the micro-concave roller coating technology, the mixed solution of acrylic resin and PMMA microbeads is uniformly coated on the upper surface of the core layer to form a core layer with diffusion coating on the upper surface for standby; meanwhile, using the micro-molding technology, the prism structure is formed on the PET substrate to prepare a prism film for standby; the prism film is used as the first prism film and the second prism film; then, using the micro-concave roller coating technology, the mixed solution of acrylic resin and PMMA microbeads is uniformly coated on the lower surface of the second prism film to form a back coating layer with scratch resistance, anti-static and anti-adhesion functions; then, using the micro-concave roller coating and UV curing technology, the first PET substrate layer is bonded with the first prism film and the second prism film; finally, using the micro-concave roller coating technology, the A adhesive is coated on the lower surface of the core layer, the B adhesive is sprayed on the upper surface of the first PET substrate layer, the core layer and the first PET substrate layer are pressed together with the adhesive-coated surfaces opposite to each other, and then irradiated with ultraviolet light, so that the core layer and the first PET substrate layer are bonded together.

[0015] Preferably, the preparation steps of the A adhesive are as follows: acrylic resin and methyl methacrylate are added into a container, stirred for 15 minutes, then tripropylene glycol diacrylate is added and stirred for 15 minutes, finally triethyl phosphonoacetate and α-hydroxy ketone are added and stirred for 15 minutes, and then the mixture is left for 1 hour, the prepared solution is dropped onto a glass sheet, no flocculation and bubbles are observed, and the prepared solution is sealed and stored for standby.

[0016] Preferably, the preparation steps of the B adhesive are as follows: acrylic resin is added into a container, stirred for 15 minutes, then resorcinol monobenzoate is added and stirred for 15 minutes, then dimethyl sulfoxide is added and stirred for 15 minutes, finally diethylene glycol divinyl ether and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide are added and stirred for 15 minutes, and then the mixture is left for 1 hour, the prepared solution is dropped onto a glass sheet, no flocculation and bubbles are observed, and the prepared solution is sealed and stored for standby.

[0017] The CPP multilayer composite film of the application provides a first adhesive layer suitable for surface bonding of the core layer and the first PET substrate layer, which can match the core layer and the first PET substrate layer, and avoids warping of the film layer after bonding. BRIEF DESCRIPTION OF DRAWINGS

[0018] The following drawings are only intended to illustrate and explain the application, and do not limit the scope of the application.

[0019] Figure 1 The structure of the CPP multilayer composite film according to one embodiment of the application is shown. DETAILED DESCRIPTION

[0020] In order to make the technical features, objectives and effects of the present application clearer, the specific embodiments of the present application will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.

[0021] As shown in Figure 1 The present application proposes a CPP multi-layer composite film, the lower side of which faces the light source, and the upper side of which faces the liquid crystal panel. The CPP multi-layer composite film of the present application comprises, from top to bottom, a diffusion coating layer 10, a core layer 20, a first adhesive layer 30, a first PET substrate layer 40, a second adhesive layer 50, a first prism film 60, a third adhesive layer 70, a second prism film 80, and a back coating layer 90.

[0022] The uppermost diffusion coating layer 10 contains PMMA particles, which are coated on the core layer 20 to increase the haze shielding effect. The PMMA particles in the diffusion coating layer 10 can disperse light and improve the viewing angle width.

[0023] The core layer 20 can be any commercially available reflective polarizing film to increase the overall brightness of the composite film. In a specific embodiment, the core layer 20 of the present application can use a multi-layer reflective polarizing film. The side of the core layer 20 facing the first PET substrate layer 40 is a PEN substrate, and the thickness of the core layer 20 is 25-35 µm. Preferably, a commercially available 33 µm multi-layer optical film (MOF) or diffuse reflective polarizing film (DRPF) is used.

[0024] The first adhesive layer 30 is used to bond the core layer 20 and the lower first PET substrate layer 40 together.

[0025] The other side of the first PET substrate layer 40 is bonded to the lower first prism film 60 through the second adhesive layer 50.

[0026] The prism structure on the first prism film 60 can increase the brightness. The prism structure on the first prism film 60 can be integrally formed on the upper surface of the underlying PET substrate by conventional UV curing.

[0027] The lower surface of the PET substrate of the first prism film 60 is bonded to the prism structure of the lower second prism film 80 through the third adhesive layer 70. Similarly, the prism structure on the second prism film 80 can increase the brightness. The prism structure on the second prism film 80 can be integrally formed on the upper surface of the underlying PET substrate by conventional UV curing.

[0028] The back coating layer 90 located at the lowermost layer contains PMMA microspheres. The back coating layer 90 is coated on the lower surface of the PET substrate of the second prism film 80 to improve the scratch resistance and anti-sticking ability of the lower surface through the PMMA microspheres.

[0029] The CPP multi-layer composite film of the present application inserts a core layer 20 compared to the traditional DPP composite film, such as the DPP composite film disclosed in CN 115963662 A. Among them, the first prism film 60, the second prism film 80 and the first PET substrate layer 40 can be compounded by the process of line bonding in the prior art to reduce the amount and thickness of the adhesive bonding, thereby reducing the probability of warping.

[0030] However, as mentioned earlier, due to the thickness constraint of the inserted core layer 20 by the optical properties, the thickness cannot be too large (the thickness of the core layer sold on the market is generally 25-35 pm), so the core layer 20 can only be surface-bonded with the first PET substrate layer 40 through the first adhesive layer 30. Due to the large difference in the expansion rate of the core layer 20 and the first PET substrate layer 40, the composition selection requirement of the first adhesive layer 30 is higher, and the first adhesive layer 30 is needed to balance the expansion rate difference between the core layer 20 and the first PET substrate layer 40.

[0031] Based on the above analysis, the present application proposes a first adhesive layer 30 suitable for surface bonding, which can match the core layer 20 and the first PET substrate layer 40 to avoid warping after bonding.

[0032] Specifically, the first adhesive layer 30 of the present application is composed of two components of UV adhesive, namely A adhesive and B adhesive. The A adhesive is composed of the following components: acrylic resin 30-40 wt%, methyl methacrylate 15-30 wt%, tripropylene glycol diacrylate 10-20 wt%, a-hydroxy ketone 1-3 wt%, triethyl phosphonoacetate 5-10 wt%, and the sum of the above components is 100 wt%; the B adhesive is composed of the following components: acrylic resin 35-45 wt%, diethylene glycol divinyl ether 20-40 wt%, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide 2-4 wt%, dimethyl sulfoxide 5-10 wt%, resorcinol monobenzoate 3-8 wt%, and the sum of the above components is 100 wt%. The A adhesive is coated on the lower surface of the core layer 20, and the B adhesive is sprayed on the upper surface of the first PET substrate layer 40. The weight ratio of A adhesive and B adhesive is 10:1, and the total thickness of the adhesive layer obtained after curing of the first adhesive layer 30 is 12-18 pm.

[0033] Examples 1-3

[0034] The following table shows the preparation of A adhesive in parts by mass: add acrylic resin and methyl methacrylate in a container, stir for 15 minutes, then add tripropylene glycol diacrylate and stir for 15 minutes, finally add triethyl phosphonoacetate and α-hydroxy ketone and stir for 15 minutes, stand for 1 hour, drop the prepared solution onto the glass sheet, observe no flocculation and bubbles, and seal for storage.

[0035]

[0036] Comparative Examples 1-3

[0037] The following table shows the preparation of A adhesive in parts by mass as a comparison.

[0038]

[0039] Examples 4-6

[0040] The following table shows the preparation of B adhesive in parts by mass: add acrylic resin in a container, stir for 15 minutes, then add resorcinol monobenzoate and stir for 15 minutes, after which add dimethyl sulfoxide and stir for 15 minutes, finally add diethylene glycol divinyl ether and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and stir for 15 minutes, stand for 1 hour, drop the prepared solution onto the glass sheet, observe no flocculation and bubbles, and seal for storage.

[0041]

[0042] Comparative Examples 4-6

[0043] The following table shows the preparation of B adhesive in parts by mass as a comparison.

[0044]

[0045] Comparative Examples 7-9

[0046] The preparation of B adhesive in parts by mass is the same as Examples 4-6, but the order of the preparation steps is different.

[0047] The preparation method of Comparative Example 7 is: add acrylic resin and diethylene glycol divinyl ether in a container, stir for 15 minutes, then add phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and stir for 15 minutes, after which add dimethyl sulfoxide and stir for 15 minutes, finally add resorcinol monobenzoate and stir for 15 minutes, stand for 1 hour.

[0048] The preparation method of Comparative Example 8 is: add acrylic resin and diethylene glycol divinyl ether in a container, stir for 15 minutes, then add dimethyl sulfoxide and stir for 15 minutes, after which add phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and stir for 15 minutes, finally add resorcinol monobenzoate and stir for 15 minutes, stand for 1 hour.

[0049] The preparation method of Comparative Example 9 is as follows: the acrylic resin and diethylene glycol divinyl ether are added into a container, stirred for 15 minutes, then dimethyl sulfoxide is added and stirred for 15 minutes, then resorcinol monobenzoate is added and stirred for 15 minutes, and finally phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide is added and stirred for 15 minutes, and then left to stand for 1 hour.

[0050] The prepared liquid of Comparative Examples 7-9 is dropped onto a glass sheet, and flocculation is observed, and the liquid cannot be used.

[0051] Examples 7-9

[0052] The A adhesive prepared in Examples 1-3 is coated on one side surface of a 30 µm PEN film (10 cm x 10 cm) by micro-concave roller coating technology, the B adhesive of Examples 4-6 is sprayed on one side surface of a 100 µm PET film (10 cm x 10 cm), and the PEN film and the PET film are bonded together with the adhesive-coated surfaces opposite to each other and irradiated with ultraviolet light for 30-60 seconds, so as to bond the PEN film and the PET film together. In Example 7, the A adhesive of Example 1 is combined with the B adhesive of Example 4 for bonding; in Example 8, the A adhesive of Example 2 is combined with the B adhesive of Example 5 for bonding; and in Example 9, the A adhesive of Example 3 is combined with the B adhesive of Example 6 for bonding.

[0053] The bending degree of the bonded film layer is observed and measured at 1 hour, 24 hours, 1 week, 1 month and 3 months after bonding, respectively, wherein the film layer is placed on a glass flat plate, and the maximum height (mm) of the highest point of the film layer and the surface of the glass flat plate is measured. The maximum height of the film layer of Examples 7-9 is less than 0.1 mm, and no obvious warping is observed.

[0054] Comparative Examples 10-12

[0055] The film layers of Comparative Examples 10-12 are obtained by the same method as Examples 7-9, respectively. In Example 10, the A adhesive of Comparative Example 1 is combined with the B adhesive of Comparative Example 4 for bonding; in Example 11, the A adhesive of Comparative Example 2 is combined with the B adhesive of Comparative Example 5 for bonding; and in Example 12, the A adhesive of Comparative Example 3 is combined with the B adhesive of Comparative Example 6 for bonding.

[0056] The bending degree of the bonded film layer is observed and measured at 1 hour, 24 hours, 1 week, 1 month and 3 months after bonding, respectively, wherein the film layer is placed on a glass flat plate, and the maximum height (mm) of the highest point of the film layer and the surface of the glass flat plate is measured. The maximum height of the film layer of Examples 7-9 is less than 0.1 mm, and no obvious warping is observed.

[0057]

[0058] The film layers of Comparative Examples 13-15 were significantly warped.

[0059] Comparative Examples 13-15

[0060] The film layers of Comparative Examples 13-15 were obtained by different methods from those of Examples 7-9, in which the A adhesive and the B adhesive were respectively formed on the surfaces of the PEN film and the PET film by coating, and the remaining steps were the same. In Comparative Example 13, the A adhesive of Example 1 was combined with the B adhesive of Example 4; in Comparative Example 14, the A adhesive of Example 2 was combined with the B adhesive of Example 5; and in Comparative Example 15, the A adhesive of Example 3 was combined with the B adhesive of Example 6.

[0061] The degree of warping of the film layers after bonding was observed and measured at 1 hour, 24 hours, 1 week, 1 month, and 3 months after bonding, respectively, in which the film layers were placed on a glass flat plate, and the maximum height (mm) of the highest point of the film layers of Comparative Examples 13-15 from the surface of the glass flat plate was measured as shown in the following table. Comparative Examples 13-15

[0062]

[0063] The film layers of Comparative Examples 13-15 were initially acceptable, but the warping increased over time.

[0064] The basic parameters of the CPP composite film of the present application are shown in the following table.

[0065]

[0066] The method for preparing the CPP multi-layer composite film of the present application will be further described below with reference to the accompanying drawings. As shown in the drawings, the method for preparing the CPP multi-layer composite film of the present application includes the following steps:

[0067] First, the mixture of acrylic resin and PMMA microbeads is uniformly coated on the upper surface of the core layer 20 using a micro-embossing roller coating technique to form the core layer 20 with the diffusion coating layer 10 on the upper surface for standby.

[0068] At the same time, a prism structure is formed on a 150 µm thick PET substrate using a micro-molding technique to prepare a prism film for standby. The prism film can be used as both the first prism film 60 and the second prism film 80.

[0069] Then, the mixture of acrylic resin and PMMA microbeads is uniformly coated on the lower surface of the second prism film 80 using a micro-embossing roller coating technique to form the back coating layer 90 for scratch resistance, anti-static, and anti-adhesion.

[0070] Then, the first PET substrate layer 40 with a thickness of 100 µm is bonded with the first prism film 60 and the second prism film 80 by micro-embossing roll coating and UV curing technology, wherein the thickness of the second adhesive layer 50 and the third adhesive layer 70 bonded between the three is about 5 µm.

[0071] Finally, the core layer 20 is bonded with the first PET substrate layer 40 by micro-embossing roll coating technology. The A adhesive is coated on the lower surface of the core layer 20, and the B adhesive is sprayed on the upper surface of the first PET substrate layer 40. The surfaces of the core layer 20 and the first PET substrate layer 40 are bonded together and irradiated by ultraviolet light for 30-60 seconds.

[0072] Those skilled in the art should understand that although the present application is described in the manner of multiple embodiments, not every embodiment contains only one independent technical solution. The description in the specification is only for the sake of clarity, those skilled in the art should understand the specification as a whole and understand the technical solutions involved in each embodiment as a way of combining different embodiments to understand the protection scope of the present application.

[0073] The above is only a specific embodiment of the present application, and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principles of the present application shall fall within the scope of protection of the present application.

Claims

1. A CPP multilayer composite film, which is sequentially provided from top to bottom with a diffusion coating layer, a core layer, a first adhesive layer, a first PET substrate layer, a second adhesive layer, a first prism film, a third adhesive layer, a second prism film, and a back coating layer, characterized in that, The first adhesive layer is composed of two components of UV adhesive, A adhesive and B adhesive, wherein the A adhesive is composed of the following components: acrylic resin 30-40 parts by mass, methyl methacrylate 15-30 parts by mass, tripropylene glycol diacrylate 10-20 parts by mass, α-hydroxy ketone 1-3 parts by mass, triethyl phosphonoacetate 5-10 parts by mass; the B adhesive is composed of the following components: acrylic resin 35-45 parts by mass, diethylene glycol divinyl ether 20-40 parts by mass, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide 2-4 parts by mass, dimethyl sulfoxide 5-10 parts by mass, resorcinol monobenzoate 3-8 parts by mass; the A adhesive is coated on the lower surface of the core layer, and the B adhesive is sprayed on the upper surface of the first PET substrate layer; the core layer is a reflective polarizing film with a multilayer structure, wherein the side of the core layer facing the first PET substrate is a PEN substrate.

2. The CPP multilayer composite film of claim 1, wherein, The weight ratio of the A adhesive and the B adhesive is 10:

1.

3. The CPP multilayer composite film of claim 1, wherein, The total thickness of the adhesive layer obtained after curing of the first adhesive layer is 12-18 µm.

4. The CPP multilayer composite film of claim 1, wherein, The thickness of the core layer is 25-35 µm.

5. A method of producing a CPP multilayer composite film as claimed in any one of claims 1 to 4, characterized in that, The method comprises the following steps: first, using micro-embossing technology, the acrylic resin and PMMA microbead mixture is uniformly coated on the upper surface of the core layer to form a core layer with a diffusion coating on the upper surface for standby; at the same time, using micro-embossing technology, a prism structure is formed on the PET substrate to prepare a prism film for standby; the prism film is used as both the first prism film and the second prism film; then, using micro-embossing technology, the acrylic resin and PMMA microbead mixture is uniformly coated on the lower surface of the second prism film to form an anti-scratch, anti-static, and anti-adhesion functional back coating; thereafter, using micro-embossing and UV curing technology, the first PET substrate layer is bonded with the first prism film and the second prism film; finally, using micro-embossing technology, the A adhesive is coated on the lower surface of the core layer, and the B adhesive is sprayed on the upper surface of the first PET substrate layer, and the surfaces of the core layer and the first PET substrate layer are pressed together and irradiated with ultraviolet light, thereby bonding the core layer and the first PET substrate layer together.

6. The method of claim 5, wherein the CPP multilayer composite film is prepared by the steps of: The preparation steps of the A adhesive are as follows: acrylic resin and methyl methacrylate are added to a container, stirred for 15 minutes, then tripropylene glycol diacrylate is added and stirred for 15 minutes, finally triethyl phosphonoacetate and α-hydroxy ketone are added and stirred for 15 minutes, and then the mixture is left to stand for 1 hour, the prepared solution is added dropwise to a glass sheet, no flocculation and bubbles are observed, and the prepared solution is sealed and stored for standby.

7. The method of claim 5, wherein the CPP multilayer composite film is prepared by the steps of: The preparation steps of the B adhesive are as follows: acrylic resin is added to a container, stirred for 15 minutes, then resorcinol monobenzoate is added and stirred for 15 minutes, then dimethyl sulfoxide is added and stirred for 15 minutes, finally diethylene glycol divinyl ether and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide are added and stirred for 15 minutes, and then the mixture is left to stand for 1 hour, the prepared solution is added dropwise to a glass sheet, no flocculation and bubbles are observed, and the prepared solution is sealed and stored for standby.

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