Vehicle-mounted brightness enhancement film and formula composition

Abstract

The vehicle-mounted UV prism glue comprises a component A and a component B, the component A is a monofunctional acrylate monomer with the refractive index larger than or equal to 1.56, an acrylate group of the component A is connected with a structural component with the high refractive index, and the component B is a bifunctional acrylate monomer or oligomer with the refractive index smaller than or equal to 1.52 and containing a soft chain segment. The high brightness gain is met, and the surface of the DBEF or the peep-proof film is not crushed under the high and low temperature environment conditions.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and more specifically, to a backlight module and a display device. Background Art

[0002] The application of liquid crystal displays in daily life is becoming more and more common. As cars develop towards intelligent driving and new energy, more and more liquid crystal displays are installed in the cockpit of the car display system. Car-mounted liquid crystal displays need to have high brightness to compensate for the interference of brighter ambient light. In addition, they need to meet the performance requirements of harsh climatic conditions such as high temperature and low temperature, as well as vibration conditions during vehicle operation. The liquid crystal displays used in vehicles include core components such as liquid crystal display modules and backlight modules. Some of the car-mounted backlight modules, in order to obtain high brightness gain, superimpose a reflective polarized brightening film (also known as DBEF film, a registered trademark of 3M) on the brightening film structure layer. Some of the car-mounted backlight modules, in order to control the specific propagation angle of the displayed image, superimpose an anti-peep film (light control film, referred to as ALCF film) on the prism structure layer of the brightening film. Whether it is a reflective polarized brightening film or an anti-peep film, it is easy to be crushed by the brightening film in the simulated environment test from -40°C to high temperature 100°C.

[0003] Brightness enhancement film, also known as prism film, is an optical film with a prism structure formed by molding UV curing glue on a PET substrate using a molding process. Because the polymer undergoes a temperature change from -40°C to 100°C, the physical properties change significantly, and the elastic modulus at -40°C is often several times or even dozens of times higher than that at room temperature (25°C).

[0004] Therefore, developing a brightness enhancement film with a lower elastic modulus at low temperatures is very meaningful for improving the surface of DBEF or privacy film from being crushed. Since the LCD in the car is affected by the ambient light, the brightness enhancement film is required to have high gain characteristics. Therefore, the refractive index of the UV-curable glue used to prepare the vehicle-mounted brightness enhancement film is usually required to exceed 1.56. The current high-refractive-index UV-curable glue is achieved by increasing the benzene ring structure content or introducing high-refractive-index inorganic nanoparticles such as zirconium oxide or titanium oxide. It has the characteristics of high hardness and high elastic modulus at low and normal temperatures, which is also an important reason for the surface of DBEF or privacy film to be crushed.

[0005] CN201410226531.2 discloses a UV glue, polyurethane acrylate oligomer and a preparation method thereof, wherein the preparation method comprises the following steps: S1. preparing intermediate product A from phenyl glycidyl ether and acrylic acid; S2. preparing intermediate product B from intermediate product A by reaction with isophorone diisocyanate; S3. preparing intermediate product C from bisphenol A polyoxyethylene ether and acrylic acid; S4. reacting intermediate products B and C; S5. adding active diluent, distilling under reduced pressure, filtering and discharging. The shortcoming of this patented technology is that it cannot meet the high brightness gain requirements of vehicle-mounted displays in order to achieve the self-repairing characteristics of the brightness enhancement film.

[0006] CN201910202744.4 discloses a UV glue for reflective film, including the following raw materials by mass: 40-50 parts of polyurethane acrylate resin, 20-26 parts of diluent, 15-22 parts of trimethylolpropane trimethacrylate, 3-5 parts of optical variable powder, 0.7-1 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1.8-2 parts of photoinitiator, 0.1-0.3 parts of acrylic leveling agent and 0.15-0.25 parts of dispersant. The disadvantage of this patented technology is that the prepared UV glue is not designed for high refractive index and cannot achieve the effect of high brightness gain.

[0007] CN202310674000.9 discloses a high refractive index UV-curing glue and a preparation method thereof. In terms of mass percentage, the nanoimprint UV-curing glue includes 30-90% modified titanium oxide nanoparticles, 1-65% monofunctional monomers, and 1-65% multifunctional monomers. The disadvantage of this patented technology is that the system using metal oxide nanoparticles cannot overcome the high rigidity characteristics of the oxide structure, which is not conducive to the pressure damage of the contact surface.

[0008] CN202410201649.3 discloses a UV type acrylic glue and a preparation method thereof, and an optical film. The UV type acrylic glue is used for an optical film, and comprises, by weight: 20 to 60 parts of acrylic resin, 30 to 100 parts of a high refractive index monomer, 2 to 20 parts of a functional monomer, and 0.1 to 7 parts of a photoinitiator; the functional monomer comprises a first functional monomer and a second functional monomer, the first functional monomer comprising at least one of tetrahydrofuran acrylate, ethoxylated tetrahydrofuran acrylate, cyclotrimethylolpropane methyl acrylate, alkyl acrylate phosphate, and acryl morpholine; the second functional monomer comprises at least one of β-acryloxy propionic acid and β-methacryloxy propionic acid. The disadvantage of this patented technology is that in order to improve the adhesion to PET, a high proportion of low refractive index functional monomers is used, and the effect of high brightness gain cannot be obtained.

[0009] Therefore, for automotive applications, it is very necessary to develop a high-performance brightness enhancement film glue for use in vehicle displays to meet the requirements of high brightness gain and not cause damage to the surface of DBEF or anti-peep film under high and low temperature conditions. Summary of the invention

[0010] In order to solve the problem that the high brightness gain brightness enhancement film will not cause damage to the surface of the DBEF film or the anti-peep film under high and low temperature conditions, a brightness enhancement film glue is developed to meet the following advantages: First, the refractive index of the brightness enhancement film glue liquid is ≥1.56, and the high refractive index brings high brightness gain; Second, the prism structure layer of the brightness enhancement film will not cause damage to the surface material of the DBEF film or the anti-peep film under the conditions of -40℃ to 100℃.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] The present invention first provides a UV prism glue, comprising component A and component B, wherein component A is a monofunctional acrylate monomer having a refractive index greater than or equal to 1.56, wherein the acrylate group of component A is connected with a structural component with a high refractive index, and component B is a difunctional acrylate monomer or oligomer having a refractive index less than or equal to 1.52 and containing a soft segment. Calculated based on 100 parts by weight of the formula, the weight of component A is 50 to 80 parts, and the weight of component B is 7 to 45 parts.

[0013] Furthermore, the high-refractive-index structural component connected by the acrylate group of the component A is a structural unit containing two or more benzene rings.

[0014] The monofunctional monomer (component A) is cured by ultraviolet light, and the acrylate group is connected to the main chain of the molecule, and the structural unit connected by the acrylate becomes the side group of the main chain of the molecule.

[0015] Furthermore, the content of component A is 55, 60, 70, or 75 parts by weight.

[0016] Furthermore, the component A (monofunctional acrylate monomer with a refractive index greater than or equal to 1.56) comprises component A1 and component A2, wherein component A1 is a monofunctional acrylate monomer with a refractive index greater than or equal to 1.60, and component A2 is a monofunctional acrylate monomer with a refractive index of 1.56 to 1.58.

[0017] Furthermore, the weight range of the component A1 (monofunctional acrylate monomer having a refractive index greater than or equal to 1.60) is 20 to 80 parts, or 30 parts, 40 parts, 50 parts, 60 parts, or 70 parts.

[0018] Furthermore, the weight range of the component A2 (monofunctional acrylate monomer with a refractive index of 1.56 to 1.58) is 0 to 60 parts, or 10 parts, 20 parts, 30 parts, 40 parts, or 50 parts.

[0019] Furthermore, the component A1 (monofunctional acrylate monomer having a refractive index greater than or equal to 1.60) includes at least one of dibenzofuran methyl acrylate (DBFMA) and biphenylmethyl acrylate (BPMA).

[0020] Furthermore, the component A2 (monofunctional acrylate monomer with a refractive index of 1.56 to 1.58) includes at least one of o-Phenylphenol (EO) acrylate (OPPEA), o-Phenylphenol (EO) 2acrylate (OPP (EO) 2A), and phenoxybenzyl acrylate (PBA).

[0021] The sum of the weight parts of component A1 (monofunctional acrylate monomer with a refractive index greater than or equal to 1.60) and component A2 (monofunctional acrylate monomer with a refractive index of 1.56 to 1.58) in the formula is greater than or equal to 50 parts and less than or equal to 80 parts. If the amount is less than 50 parts, the refractive index of the formula cannot be guaranteed to reach above 1.56; if the amount is greater than 80 parts, the formula contains too much monofunctional acrylate monomer, which affects the mechanical strength deviation of the overall formula.

[0022] Furthermore, the soft segments of component B (difunctional acrylate monomers or oligomers having a refractive index of less than or equal to 1.52 and containing soft segments) include polyethylene glycol segments, polypropylene glycol segments, polycaprolactone segments, polyester polyurethane segments, polyether polyurethane segments, and the like.

[0023] Furthermore, the component B includes at least one of ethoxylated or propoxylated difunctional acrylates having a refractive index less than or equal to 1.52: m ethoxylated or propoxylated bisphenol A diacrylate, wherein the ethoxylation or propoxylation number m is any one of 10 to 30 (or 15, 18, 20, 25, 28); n ethoxylated or propoxylated bisphenol fluorene diacrylate, wherein the ethoxylation or propoxylation number n is any one of 20 to 30 (or 22, 24, 28); polyethylene glycol diacrylate, wherein the degree of polymerization p of ethylene glycol is any one of 4 to 20 (or 6, 8, 10, 12, 15, 17, 18).

[0024] Furthermore, the component B includes polyester-type polyurethane acrylate oligomers containing flexible polyester segments, polyether-type polyurethane acrylate oligomers containing flexible polyether segments, epoxy acrylic resins modified with flexible segments, and polyether acrylate oligomers.

[0025] The chemical composition and molecular weight of the soft segment of the component B (difunctional acrylate monomer or oligomer with a refractive index of less than or equal to 1.52 and containing a soft segment) determine the compactness and flexibility of the main chain cross-linking network of the UV-curable film-forming material.

[0026] If the component B (a difunctional acrylate monomer or oligomer having a refractive index of less than or equal to 1.52 and containing a soft segment) accounts for less than 7 parts in the formula, the physical properties of the film-forming material will be relatively low; if it accounts for more than 45 parts in the formula, the film-forming material will contain a higher number of cross-linking nodes, resulting in a higher elastic modulus of the film-forming material.

[0027] Furthermore, the content of component B is 10, 15, 20, 25, 30, 35, or 40 parts by weight.

[0028] The difunctional acrylate monomer or oligomer (component B) forms a certain cross-linked network after UV curing. The soft chain segment of the difunctional acrylate monomer or oligomer forms the chain segment of the cross-linked network. The softer the soft chain segment is and the larger the molecular weight of the soft chain segment is, the more room for activity the rigid structural unit of the side group has.

[0029] Furthermore, the UV prism glue includes component C, which is a trifunctional acrylate monomer or oligomer having a refractive index less than or equal to 1.49 and containing a soft segment.

[0030] Furthermore, the weight proportion of component C is less than or equal to 10 parts, or is 2, 4, 5, 6, or 8 parts.

[0031] The trifunctional acrylate monomer or oligomer (component C) has greater cross-linking characteristics and forms a denser cross-linked network structure after UV curing, which helps to improve the mechanical strength, but also brings a higher modulus.

[0032] Furthermore, the UV prism glue includes a photoinitiator, and the weight portion of the photoinitiator is 2 to 4 parts.

[0033] Furthermore, the weight proportion of the photoinitiator is 3 parts or 4 parts.

[0034] Furthermore, the UV prism glue includes an ultraviolet absorber, and the weight portion of the ultraviolet absorber is less than or equal to 1 part.

[0035] Furthermore, the weight percentage of the ultraviolet absorber is 0.2, 0.4, 0.5, 0.6, or 0.8.

[0036] Furthermore, the UV prism glue includes an organic silicon additive, and the weight portion of the organic silicon additive is less than or equal to 1 part.

[0037] Furthermore, the weight proportion of the organosilicon additive is 0.2, 0.4, 0.5, 0.6 or 0.8.

[0038] Furthermore, the soft segments of component C (trifunctional acrylate monomers or oligomers having a refractive index of less than or equal to 1.49 and containing soft segments) include polyethylene glycol segments, polypropylene glycol segments, polycaprolactone segments, polyester polyurethane segments, polyether polyurethane segments, and the like.

[0039] Furthermore, the component C includes at least one of ethoxylated or propoxylated trimethylolpropane triacrylate, ethoxylated or propoxylated glycerol triacrylate, polyether acrylate oligomer, or polyurethane triacrylate oligomer.

[0040] Furthermore, the photoinitiator includes at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 1-hydroxycyclohexyl phenyl ketone (184), methyl benzoylformate (MBF), diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO), phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO, 819), and ethyl 2,4,6-trimethylbenzoyl phenylphosphonate (TPO-L).

[0041] Furthermore, the amount of the photoinitiator is 2 to 4 parts. If the amount of the photoinitiator is less than 2 parts, the curing speed of the formula is slow, affecting the production efficiency; if the amount of the photoinitiator is more than 4 parts, more photoinitiator residues in the cured product will affect the performance. Preferably, two initiators are used in combination, one of which is one of the photoinitiators 1173, 184 or MBF with strong absorption in the UV band less than 365nm, and the other is one of the photoinitiators TPO, TPO-L or BAPO with strong absorption in the UV band greater than 365nm.

[0042] Furthermore, the other additives are added according to the needs of the formula application. From the functional point of view, they include ultraviolet absorbers, antistatic agents, defoamers, substrate wetting and leveling agents and other substances. Ultraviolet absorbers can improve the brightness enhancement film to maintain a low yellowing value in sunlight exposure or blue light aging experiments. Antistatic agents can reduce the accumulation of static electricity on the film, improve the film cutting powder or reduce the adsorption of dust on the film. Defoamers can inhibit or eliminate bubbles in the glue during the production process of preparing the brightening film structure layer. The substrate wetting and leveling agent can improve the appearance of the film surface of the brightening film structure layer. In an embodiment of the present invention, the ultraviolet absorber is a benzotriazole-type UV absorber (product model UV384-2), and the substrate wetting and leveling agent is a polyether-modified silicone additive produced by BYK (product model BYK333). The amount of the additive in the formula is 0 to 1 part.

[0043] The UV prism glue of the present invention does not use inorganic nanoparticles.

[0044] The present invention also provides a method for preparing UV prism glue, comprising:

[0045] Step (1), weighing each component in the formula according to weight, and adding them into a stirring container in sequence;

[0046] Step (2), turn on the stirrer, adjust the stirring speed from low to high to 1000 rpm and continue stirring for about 1 hour until the mixture is completely dissolved and evenly dispersed.

[0047] The present invention also provides an optical brightness enhancement film, comprising a substrate and a prism layer, wherein the prism layer is cured by ultraviolet light using the UV prism glue, and a focusing micro-prism structure is arranged on the surface of the substrate to form the optical brightness enhancement film.

[0048] Furthermore, the substrate includes a polyethylene terephthalate (PET) film and a polycarbonate (PC) film, and has a thickness of 25 to 250 microns.

[0049] The present invention also provides a method for preparing an optical brightness enhancement film, comprising:

[0050] Step (1): preparing a substrate, including a polyethylene terephthalate (PET) film and a polycarbonate (PC) film;

[0051] Step (2): applying the UV prism glue on the surface of the substrate, and rolling a mold having a complementary structure to the focusing micro-prism structure layer;

[0052] Step (3): using ultraviolet light to cure the UV prism glue, and disposing the focusing micro-prism structure layer on the surface of the substrate layer to obtain the optical brightness enhancement film.

[0053] The present invention also provides an application of UV prism glue in an optical brightening film. The optical brightening film includes a substrate and a prism layer. The prism layer is obtained by ultraviolet curing of the UV prism glue, has high brightness gain, and the prism structure layer will not cause damage to the surface material of the DBEF or the anti-peep film under the condition of -40°C to 100°C.

[0054] Furthermore, the optical brightness enhancement film is applied to a vehicle-mounted display.

[0055] The brightness enhancement film glue developed for vehicle-mounted applications provided by the present invention meets the characteristics of high brightness gain and no crushing on the surface of DBEF or anti-peep film under high and low temperature environmental conditions.

[0056] In order to verify the performance of the vehicle-mounted prism glue of the present invention, a method for preparing the optical brightness enhancement film of the present invention comprises the following steps:

[0057] Preparation of substrate: The substrates used in the examples and comparative examples of the present invention are all PET optical films with primer coatings on both sides produced by Yihua Dongli Polyester Film Co., Ltd., and the thickness of the substrate is 188 μm.

[0058] Preparation of prism layer structure: UV curing resin is coated on the surface of the substrate layer, and then a mold having a complementary structure to the focusing micro-prism structure layer is rolled to form the UV curing resin into a focusing micro-prism structure layer, and then UV light is irradiated to cure the UV curing resin, thereby setting the focusing micro-prism structure layer on the surface of the substrate layer to obtain the optical brightness enhancement film.

[0059] Prism structure parameters: prism angle: 90 degrees, the peak spacing between two adjacent prism structures in the prism layer is: 50±1um. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 : Dibenzofuran methyl acrylate (DBFMA): liquid refractive index 1.615~1.620.

[0061] Figure 2 : Biphenylmethyl acrylate (BPMA): liquid refractive index 1.600~1.605.

[0062] Figure 3 : o-Phenylphenol (EO) acrylate (OPPEA for short): liquid refractive index 1.575~1.578.

[0063] Figure 4: o-phenylphenoxyethyl ethoxy acrylate: liquid refractive index 1.560~1.565.

[0064] Figure 5 : Phenoxybenzyl acrylate: liquid refractive index 1.563 ~ 1.567.

[0065] Figure 6 : Photograph of the brightness enhancement film of Example 1. DETAILED DESCRIPTION

[0066] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] According to one aspect of the present invention, a vehicle-mounted UV prism glue comprises the following components in parts by weight:

[0068] The monofunctional acrylate monomer with a refractive index greater than or equal to 1.56 is used in an amount greater than or equal to 50 parts and less than or equal to 80 parts; the difunctional acrylate monomer or oligomer with a refractive index less than or equal to 1.52 and containing a soft segment is used in an amount greater than or equal to 7 parts and less than or equal to 45 parts; the trifunctional acrylate monomer or oligomer with a refractive index less than or equal to 1.49 and containing a soft segment is used in an amount less than or equal to 10 parts; the photoinitiator is used in an amount greater than or equal to 2 parts and less than or equal to 4 parts; other additives are used in an amount less than or equal to 1 part.

[0069] The vehicle-mounted UV prism glue provided by the present invention has a refractive index greater than or equal to 1.56, and the prism structure layer of the brightness enhancement film prepared therefrom will not cause crushing of DBEF or anti-peep film surface materials under the condition of -40°C to 100°C.

[0070] The UV prism glue is formulated with monofunctional acrylate monomers with a refractive index greater than or equal to 1.60 and monofunctional acrylate monomers with a refractive index of 1.56 to 1.58, and the sum of these two monomers accounts for greater than or equal to 50 parts and less than or equal to 80 parts in the formula. There are two main purposes: first, this type of high-refractive-index monomer contributes to the refractive index of the UV prism glue being greater than or equal to 1.56; second, the high-refractive-index rigid structural unit of the high-refractive-index monofunctional monomer will not be formed on the molecular main chain of the brightness enhancement film, but will be distributed next to the molecular main chain in the form of a side group, so that there is a larger free volume between the molecular chains.

[0071] The UV prism glue is formulated with difunctional or trifunctional acrylate monomers or oligomers containing flexible segments with a refractive index of less than or equal to 1.52. It mainly has two purposes: first, difunctional or trifunctional acrylates form a certain cross-linking network after UV curing, so that the prepared brightness enhancement film has higher mechanical properties and meets the test of various environmental conditions; second, difunctional or trifunctional acrylate monomers or oligomers contain flexible segments, so that the formed cross-linking network has better flexibility and lower rigidity, so that the prism structure layer of the brightness enhancement film will not cause damage to the DBEF or anti-peep film surface material under the conditions of -40℃ to 100℃.

[0072] In order to make it easier to understand the functional features and advantages that can be achieved by the present invention, the preferred embodiments of the present invention are described in detail below by weight:

[0073] Table 1: Some materials involved in the following examples and comparative examples of this application:

[0074]

[0075]

[0076] Embodiment 1:

[0077] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 50 parts by weight of dibenzofuran methacrylate (M1082); 45 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 2 parts by weight of a photoinitiator (184); 2 parts by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.567 at 25°C.

[0078] The preparation method thereof comprises

[0079] Step (1), weighing each component in the formula according to weight, and adding them into a stirring container in sequence;

[0080] Step (2), turn on the stirrer, adjust the stirring speed from low to high to 1000 rpm and continue stirring for about 1 hour until the mixture is completely dissolved and evenly dispersed.

[0081] A method for preparing a brightness enhancement film:

[0082] Step (1): preparing a substrate, a PET optical film with a thickness of 188 μm and a primer layer on both sides produced by Yihua Dongli Polyester Film Co., Ltd.;

[0083] Step (2): applying the UV prism glue on the surface of the substrate, and rolling a mold having a complementary structure to the focusing micro-prism structure layer;

[0084] Step (3): using ultraviolet light to cure the UV prism glue, and disposing the focusing micro-prism structure layer on the surface of the substrate layer to obtain the optical brightness enhancement film.

[0085] The preparation methods of other embodiments and comparative examples are the same as those of Example 1.

[0086] Embodiment 2:

[0087] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 50 parts by weight of dibenzofuran methacrylate (M1082); 30 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 15 parts by weight of (30) ethoxylated bisphenol A diacrylate (M2300); 2 parts by weight of a photoinitiator (184); 2 parts by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.564 at 25° C.

[0088] Embodiment 3:

[0089] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 60 parts by weight of dibenzofuran methacrylate (M1082); 27 parts by weight of (30) ethoxylated bisphenol A diacrylate (M2300); 10 parts by weight of (9) ethoxylated trimethylolpropane triacrylate (EM2382); 1.5 parts by weight of a photoinitiator (184); and 1.5 parts by weight of a photoinitiator (TPO). The vehicle-mounted brightening film glue has a refractive index of 1.566 at 25°C.

[0090] Embodiment 4:

[0091] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 30 parts by weight of dibenzofuran methyl acrylate (M1082); 30 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 27 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 10 parts by weight of (30) ethoxylated bisphenol A diacrylate (M2300); 1.5 parts by weight of a photoinitiator (184); and 1.5 parts by weight of a photoinitiator (TPO). The vehicle-mounted brightening film glue has a refractive index of 1.563 at 25°C.

[0092] Embodiment 5:

[0093] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 30 parts by weight of dibenzofuran methyl acrylate (M1082); 40 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 22 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 5 parts by weight of (6) ethoxylated trimethylolpropane triacrylate (EM2376); 1 part by weight of a photoinitiator (184); 1 part by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.568 at 25°C.

[0094] Embodiment 6:

[0095] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 20 parts by weight of dibenzofuran methacrylate (M1082); 50 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 17 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 10 parts by weight of (9) ethoxylated trimethylolpropane triacrylate (EM2382); 1 part by weight of a photoinitiator (184); 1 part by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.562 at 25°C.

[0096] Embodiment 7:

[0097] The invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 15 parts by weight of dibenzofuran methacrylate (M1082); 15 parts by weight of biphenyl methacrylate (M1192); 20 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 20 parts by weight of o-phenylphenoxyethyl ethoxy acrylate (M1144); 15 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 10 parts by weight of (6) ethoxylated trimethylolpropane triacrylate (EM2376); 2 parts by weight of a photoinitiator (184); 2 parts by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.562 at 25°C.

[0098] Embodiment 8:

[0099] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 80 parts by weight of biphenyl methyl acrylate (M1192); 17 parts by weight of polyurethane acrylate (CN991); 1.5 parts by weight of photoinitiator (184); and 1.5 parts by weight of photoinitiator (TPO). The refractive index of the vehicle-mounted brightening film glue at 25° C. is 1.580.

[0100] Embodiment 9:

[0101] The invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 10 parts by weight of dibenzofuran methacrylate (M1082); 10 parts by weight of biphenyl methacrylate (M1192); 40 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 20 parts by weight of o-phenylphenoxyethyl ethoxy acrylate (M1144); 7 parts by weight of (30) ethoxylated bisphenol A diacrylate (M2300); 10 parts by weight of (9) ethoxylated trimethylolpropane triacrylate (EM2382); 1 part by weight of a photoinitiator (184); 1 part by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.563 at 25°C.

[0102] Comparative Example 1:

[0103] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 20 parts by weight of dibenzofuran methacrylate (M1082); 25 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 40 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 10 parts by weight of (6) ethoxylated trimethylolpropane triacrylate (EM2376); 2 parts by weight of a photoinitiator (184); 2 parts by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.548 at 25°C.

[0104] Comparative Example 2:

[0105] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 20 parts by weight of dibenzofuran methyl acrylate (M1082); 50 parts by weight of o-phenylphenoxyethyl acrylate (M1142); 27 parts by weight of (6) ethoxylated trimethylolpropane triacrylate (EM2376); 1 part by weight of a photoinitiator (184); 1 part by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.555 at 25° C.

[0106] Comparative Example 3:

[0107] The present invention provides a vehicle-mounted brightening film glue, the vehicle-mounted brightening film glue comprising: 45 parts by weight of biphenyl methyl acrylate (M1192); 40 parts by weight of o-phenyl phenoxyethyl acrylate (M1142); 10 parts by weight of (10) ethoxylated bisphenol A diacrylate (EM2265); 2 parts by weight of a photoinitiator (184); 2 parts by weight of a photoinitiator (TPO); 0.5 parts by weight of an ultraviolet absorber (UV384-2); and 0.5 parts by weight of an organic silicon slip agent (BYK333). The vehicle-mounted brightening film glue has a refractive index of 1.576 at 25°C.

[0108] Examples 1 to 9 and Comparative Examples 1 to 3: According to the formulas provided in Table 2 and Table 3, a brightening film glue for vehicle use was prepared.

[0109] Table 2: Glue for vehicle-mounted brightness enhancement film described in Examples 1 to 9

[0110]

[0111] Table 3: Glues for vehicle-mounted brightening films described in Comparative Examples 1 to 3

[0112]

[0113] Preparation of prism layer structure: The vehicle-mounted brightness enhancement film glue of Examples 1 to 11 and Comparative Examples 1 to 3 is coated on the surface of the PET optical film, and then rolled on a mold having a complementary structure to the light-gathering micro-prism structure layer to form a light-gathering micro-prism structure layer, and then cured by ultraviolet light irradiation to obtain the optical brightness enhancement film. Prism structure parameters: prism angle: 90 degrees, the peak spacing between two adjacent prism structures of the prism layer is: 50±1um.

[0114] Test Example 1

[0115] In order to show that the UV prism glue prepared in this application and the brightness enhancement film prepared therefrom have high brightness gain and the prism structure layer will not cause damage to the DBEF or anti-peep film surface material under the conditions of -40°C to 100°C, the following performance tests are now conducted:

[0116] 1. Refractive index test: Drop the prepared UV prism glue on an Abbe refractometer (WAY-2S) to test its refractive index at a temperature of 25° C. The refractive indices described in this application are all the refractive indices of liquids, and the tests are performed under the same test conditions.

[0117] 2. Hardness test:

[0118] 1. Preparation of test samples: Take 2g of UV prism glue to be tested and place it between two 50μm thick PET release films. The surface of the PET silicone release agent contacts the glue. Use a glass plate to press the glue into a disc with a diameter of about 3cm at a certain pressure. Use a UV lamp to cure the front and back sides once, and peel off the release film.

[0119] 2. Test the Shore hardness: Place the UV-cured disc at room temperature for 2 hours, and then use a digital Shore hardness tester to test the hardness of the cured film.

[0120] 3. Module loading test

[0121] 1. The brightness enhancement film is formed into a backlight film group according to the following backlight module structure: Structure 1, diffuser film +

[0122] Brightness enhancement film + brightness enhancement film + DBEF are superimposed (abbreviated as D+B+B+DBEF); Structure 2, diffusion film + brightness enhancement film + brightness enhancement film + anti-peep film (abbreviated as D+B+B+ALCF). The back of DBEF or ALCF is in contact with the prism structure surface of the brightness enhancement film.

[0123] 2. Test at -40℃ for 1000 hours: Place the backlight module at -40℃ for 1000 hours. After taking it out, disassemble the backlight module and observe the appearance of the brightness enhancement film structure, privacy film or DBEF surface.

[0124] 3. Test at 100°C for 1000 hours: Place the backlight module at 100°C for 1000 hours. After taking it out, disassemble the backlight module and observe the appearance of the brightness enhancement film structure, anti-peep film or DBEF surface.

[0125] 4. Test results:

[0126] Table 4: Results of performance tests:

[0127]

[0128]

[0129] Experimental data analysis: In Examples 1 and 2, the amount of high-refractive-index monofunctional monomers used is 50 parts, and the amount of difunctional flexible monomers used is 45 parts. The difference is that some flexible monomers in Example 2 are longer than the flexible segments in Example 1, which is manifested as a lower hardness in Example 2. In the test at -40°C, Example 2 has no crushing damage, while the DBEF film and ALCF film in Example 1 have slight crushing damage. In Examples 3 to 7, the weight content of monofunctional monomers with a refractive index greater than or equal to 1.56 in the formula is between 60 and 70 parts. Through the optimized combination of difunctional and trifunctional acrylates containing flexible segments, the Shore hardness is between 82D and 90D, showing that there is no appearance problem in the tests at -40°C and 100°C. In Example 8, Example 9 and Comparative Example 3, the amount of monofunctional monomer is greater than or equal to 80 parts. When the content of difunctional or trifunctional acrylate monomer or oligomer in the formula is less than or equal to 17 parts, the prism structure is soft, which is manifested as the problem of deformation of the prism structure under 100°C. In Comparative Examples 1 and 2, the amount of high-refractive-index monofunctional monomer is less than 50 parts, and the refractive index of the formula does not meet the requirement of 1.56. The content of trifunctional acrylate in Comparative Example 2 is relatively high, and the rigidity is relatively large, which is manifested as the problem of crushing DBEF and anti-peep film in the test at -40°C. From the above data, it can be seen that in Examples 3 to 7, the weight content of monofunctional monomers with a refractive index greater than or equal to 1.56 in the formula is between 60 and 70 parts, and the hardness of the prism structure layer is between 82D and 90D, showing better comprehensive performance.

[0130] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. All equivalent changes and modifications made according to the content of the present invention are included in the patent scope of the present invention.

Claims

1. A UV prism glue, comprising component A and component B, wherein component A is a monofunctional acrylate monomer having a refractive index greater than or equal to 1.56, the acrylate group of component A is connected with a structural component with a high refractive index, and component B is a difunctional acrylate monomer or oligomer having a refractive index less than or equal to 1.52 and containing a soft segment. Based on 100 parts by weight of the formula, the weight of component A is 50 to 80 parts, and the weight of component B is 7 to 45 parts.

2. The UV prism glue according to claim 1, characterized in that: The high-refractive-index structural component connected by the acrylate group of the component A is a structural unit containing two or more benzene rings.

3. The UV prism glue according to claim 1, characterized in that: The component A (monofunctional acrylate monomer with a refractive index greater than or equal to 1.56) comprises component A1 and component A2, wherein component A1 is a monofunctional acrylate monomer with a refractive index greater than or equal to 1.60, and component A2 is a monofunctional acrylate monomer with a refractive index of 1.56-1.

58.

4. The UV prism glue according to claim 1, characterized in that: The weight range of the component A1 (monofunctional acrylate monomer having a refractive index greater than or equal to 1.60) is 20 to 80 parts.

5. The UV prism glue according to claim 1, characterized in that: The weight range of the component A2 (monofunctional acrylate monomer having a refractive index of 1.56 to 1.58) is 0 to 60 parts.

6. The UV prism glue according to claim 1, characterized in that: The component A1 (monofunctional acrylate monomer having a refractive index greater than or equal to 1.60) includes at least one of dibenzofuran methacrylate and biphenyl methacrylate.

7. The UV prism glue according to claim 1, characterized in that: The component A2 (monofunctional acrylate monomer with a refractive index of 1.56 to 1.58) includes at least one of o-phenylphenoxyethyl acrylate, o-phenylphenoxyethyl ethoxy acrylate, and phenoxybenzyl acrylate.

8. The UV prism glue according to claim 1, characterized in that: The soft segments of component B (difunctional acrylate monomers or oligomers having a refractive index of less than or equal to 1.52 and containing soft segments) include polyethylene glycol segments, polypropylene glycol segments, polycaprolactone segments, polyester polyurethane segments, polyether polyurethane segments, and the like.

9. The UV prism glue according to claim 1, characterized in that: The component B includes at least one of ethoxylated or propoxylated difunctional acrylates having a refractive index less than or equal to 1.52: m ethoxylated or propoxylated bisphenol A diacrylate, wherein the ethoxylation or propoxylation number m is any one of 10 to 30 (or 15, 18, 20, 25, 28); n ethoxylated or propoxylated bisphenol fluorene diacrylate, wherein the ethoxylation or propoxylation number n is any one of 20 to 30 (or 22, 24, 28); polyethylene glycol diacrylate, wherein the polymerization degree p of ethylene glycol is any one of 4 to 20 (or 6, 8, 10, 12, 15, 17, 18).

10. The UV prism glue according to claim 1, characterized in that: The component B comprises polyester-type polyurethane acrylate oligomer containing flexible polyester segments, polyether-type polyurethane acrylate oligomer containing flexible polyether segments, epoxy acrylic resin modified with flexible segments, and polyether acrylate oligomer.

11. The UV prism glue according to claim 1, characterized in that: The UV prism glue comprises component C, which is a trifunctional acrylate monomer or oligomer having a refractive index less than or equal to 1.49 and containing a soft segment.

12. The UV prism glue according to claim 1, characterized in that: The weight portion of component C is less than or equal to 10 parts.

13. The UV prism glue according to claim 1, characterized in that: The UV prism glue comprises a photoinitiator, and the weight portion of the photoinitiator is 2 to 4 parts.

14. The UV prism glue according to claim 1, characterized in that: The soft segments of component C (trifunctional acrylate monomers or oligomers having a refractive index of less than or equal to 1.49 and containing soft segments) include polyethylene glycol segments, polypropylene glycol segments, polycaprolactone segments, polyester polyurethane segments, polyether polyurethane segments, and the like.

15. A method for preparing the UV prism glue according to any one of claims 1 to 14, comprising: Step (1), weighing each component in the formula according to weight, and adding them into a stirring container in sequence; Step (2), turn on the stirrer, adjust the stirring speed from low to high to 1000 rpm and continue stirring for 1 hour until the mixture is completely dissolved and evenly dispersed.

16. An optical brightness enhancement film, comprising a substrate and a prism layer, wherein the prism layer is cured by ultraviolet light using the UV prism glue of any one of claims 1 to 14, and a focusing micro-prism structure is arranged on the surface of the substrate to form the optical brightness enhancement film.

17. A method for preparing an optical brightness enhancement film, comprising: Step (1): preparing a substrate, including a polyethylene terephthalate (PET) film and a polycarbonate (PC) film; Step (2): applying the UV prism glue on the surface of the substrate, and rolling a mold having a complementary structure to the focusing micro-prism structure layer; Step (3): using ultraviolet light to cure the UV prism glue, and disposing the focusing micro-prism structure layer on the surface of the substrate layer to obtain the optical brightness enhancement film.

18. The preparation method according to claim 17, characterized in that: The substrate includes a polyethylene terephthalate (PET) film and a polycarbonate (PC) film, and has a thickness of 25 to 250 microns.

19. Application of the UV prism glue of any one of claims 1-14 in an optical brightening film, the optical brightening film comprising a substrate and a prism layer, the prism layer being obtained by ultraviolet curing of the UV prism glue, having high brightness gain and the prism structure layer not causing damage to the surface material of the DBEF or the anti-peep film under the condition of -40°C to 100°C.

20. The use according to claim 19, characterized in that The optical brightness enhancement film is applied to a vehicle-mounted display.

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