Heat transfer printing reflective film, light guide plate and method for forming reflective structure on light guide plate base material

Abstract

The invention relates to the technical field of display, in particular to a heat transfer printing reflective film, a light guide plate and a method for forming a reflective structure on a light guide plate base material. The heat transfer printing reflective film comprises a base film layer, a release layer, a protective layer, a metal reflective layer and a hot melt adhesive layer which are sequentially stacked and combined in the first stacking direction, and the hot melt adhesive layer is configured to be capable of being combined to a light guide plate base material under the heat effect. The base film layer is configured to be capable of being separated from the heat transfer printing reflective film under the condition that the hot melt adhesive layer is connected to the light guide plate base material.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a thermal transfer reflective film, a light guide plate, and a method for forming a reflective structure on a light guide plate substrate. Background Art

[0002] The light guide plate is a key component in the backlight module for liquid crystal display. Its light output intensity and light output uniformity directly determine the brightness of the backlight module and the uniformity of the surface light source, which in turn affects the brightness, brightness uniformity and picture quality of the liquid crystal display device. Summary of the invention

[0003] In order to improve the overall brightness of the backlight module, a reflective film can be set on the side of the light guide plate to reflect the light that is intended to be emitted from the side back into the light guide plate, thereby increasing the energy of the light emitted from the light emitting surface of the light guide plate. However, with the thinness of terminal products, the thickness of the light guide plate is getting thinner and thinner, and some are even close to 0.3mm. In this case, if the reflective film is formed on the side of the light guide plate by conventional manual or mechanical pasting methods, it will be difficult to meet the use requirements; if the reflective film is formed on the side of the light guide plate by evaporation, the process flow is complicated and the equipment is expensive. If it is applied to the production of light guide plates, the production cost will be significantly increased.

[0004] In view of this, the present application proposes a thermal transfer reflective film, a light guide plate, and a method for forming a reflective structure on a light guide plate substrate.

[0005] In a first aspect, a thermal transfer reflective film is provided, comprising a base film layer, a release layer, a protective layer, a metal reflective layer and a hot melt adhesive layer which are sequentially stacked and bonded along a first stacking direction, wherein the hot melt adhesive layer is configured to be bonded to a light guide plate substrate under the action of heat, and the base film layer is configured to be able to be separated from the thermal transfer reflective film when the hot melt adhesive layer is bonded to the light guide plate substrate.

[0006] In some possible implementations, the metal reflective layer includes metal and silicon dioxide bonded to the protective layer by evaporation, and the mass ratio of the silicon dioxide to the metal is less than 5:100;

[0007] Preferably, the mass ratio of the silicon dioxide to the metal is 2 to 4:100.

[0008] The metal is silver or aluminum.

[0009] In some possible implementations, the thermal transfer reflective film is used to be attached to the first side of the stacked body to transfer the metal reflective layer to the second side of the light guide plate substrate, wherein the stacked body includes a plurality of light guide plate sheets stacked along a second stacking direction intersecting the first stacking direction, each of the light guide plate sheets includes one light guide plate substrate and a protective film that is peelably laminated and bonded to at least one side of the light guide plate substrate along the second stacking direction, and the second side and the third side of the protective film define the first side;

[0010] The hot melt adhesive layer is configured as follows: under the action of the heat, it is bonded to the second side of the light guide plate substrate and has a first bonding force, and is bonded to the third side of the protective film and has a second bonding force, and the bonding force between the base film layer and the protective layer provided by the release layer is greater than the second bonding force but less than the first bonding force.

[0011] In some possible implementations, the release layer is a thermal release layer whose release force with the base film layer is reduced under the action of heat.

[0012] In some possible implementations, the solid content of the release agent in the release layer is 0.2 to 0.4 g / m 2 The solid content of the thermoplastic acrylic resin in the hot melt adhesive layer is 1.8 to 2.0 g / m 2 .

[0013] In the second aspect, a light guide plate is proposed, comprising a light emitting surface, a bottom surface opposite to the light emitting surface, a light incident surface respectively connecting the light emitting surface and the bottom surface, and a plurality of side surfaces, at least one of the plurality of side surfaces being provided with a reflective film for reflecting light toward the interior of the light guide plate by means of thermal transfer.

[0014] In some possible implementations, the reflective film includes a hot melt adhesive layer, a metal reflective layer, and a protective layer stacked in sequence in a direction away from the side surface, the metal reflective layer includes a metal and silicon dioxide bonded to the protective layer by evaporation, and the mass ratio of the silicon dioxide to the metal is less than 5:100;

[0015] Preferably, the mass ratio of the silicon dioxide to the metal is 2 to 4:100.

[0016] The metal is silver or aluminum.

[0017] In some possible implementations, the solid content of the thermoplastic acrylic resin in the hot melt adhesive layer is 1.8 to 2.0 g / m 2 .

[0018] In a third aspect, a method for forming a reflective structure on a light guide plate substrate is proposed, comprising:

[0019] Providing the thermal transfer reflective film as described in the first aspect;

[0020] providing the laminate;

[0021] Thermally pressing the thermal transfer reflective film onto the first side of the laminate;

[0022] The base film layer is torn off so that a portion of the thermal transfer reflective film follows the base film layer and leaves from the first side.

[0023] In some possible implementations, the step of heat-compression bonding the heat transfer reflective film to the first side of the laminate includes:

[0024] Bonding the heat transfer reflective film to the first side of the laminate by heat compression, wherein the reflective film bonded to the first side has a protruding portion extending beyond the first side;

[0025] The step of tearing the base film layer so that a portion of the reflective film follows the base film layer and leaves from the first side surface comprises:

[0026] The protruding portion is torn to tear the base film layer, thereby causing a portion of the reflective film to follow the base film layer and leave from the first side.

[0027] According to the thermal transfer reflective film provided by the present application, the metal reflective layer can be easily and stably thermally transferred to the side of the light guide plate substrate to form a stable reflective structure on the corresponding side of the light guide plate. Moreover, after the metal reflective layer in the thermal transfer reflective film is transferred to the side of the light guide plate, there are no problems such as bright lines and bright spots that may occur in ordinary reflective structures, and the light output at the far end of the light guide plate is uniform and maintains a high light output brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present application, rather than limiting the present application.

[0029] Figure 1 It is a schematic diagram of a method for forming a reflective structure on a light guide plate substrate provided in one embodiment of the present application.

[0030] Figure 2 is with Figure 1 Corresponding flow chart of a method for forming a reflective structure on a light guide plate substrate.

[0031] Figure 3It is a schematic diagram of a light guide plate provided in an embodiment of the present application when viewed from above.

[0032] Figure 4 yes Figure 3 A schematic side view of the light guide plate shown.

[0033] Figure 5 yes Figure 4 An enlarged schematic diagram of a portion of .

[0034] Figure 6 yes Figure 3 The schematic diagram of the light guide plate shown is applied to the edge-type backlight module.

[0035] Figure 7 The figure shows the optical quality of the far light end of the light guide plate when light is incident from the light incident surface side, when the metal reflective layer is entirely formed of aluminum, provided in a pair of ratios of the present application.

[0036] Figure 8 The figure shows the optical quality of the far light end of the light guide plate when light is incident from the light incident surface side, when the metal reflective layer provided by an embodiment of the present application is formed of aluminum and silicon dioxide, and the mass ratio of silicon dioxide to aluminum is 3.53:100.

[0037] Fig. 9 Schematic diagram of Gaussian scattering of a light ray after passing through a metal reflective layer doped with silicon dioxide molecules.

[0038] Description of reference numerals:

[0039] DR1-first stacking direction, DR2-second stacking direction;

[0040] 100-thermal transfer reflective film, 101-extending portion;

[0041] 200- stacked body, 200a- first side;

[0042] 300-light guide plate, 300a-light incident surface, 300b-bottom surface, 300c-light emitting surface, 300d, 300e, 300f-side surfaces;

[0043] 1-base film layer, 2-release layer, 3-protective layer, 4-metal reflective layer, 5-hot melt adhesive layer;

[0044] 6-light guide plate;

[0045] 7-light guide plate substrate, 7a-second side surface;

[0046] 8-protective film, 8a-third side;

[0047] 9-light-guiding microstructure;

[0048] 10-Reflective film;

[0049] 11-LED light source. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the embodiment of the present application will be clearly and completely described below in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application. It can be understood that, in the absence of conflict, some technical means of the various embodiments described herein can be replaced or combined with each other.

[0051] In the description of this application, if there are terms such as "first", "second", etc., they are only used to distinguish the objects described and do not have any order or technical meaning. Therefore, an object defined as "first", "second", etc. may explicitly or implicitly include one or more of the objects, and, for example, the term "first element" itself does not mean the existence of the "second element", and the term "second element" itself does not mean the existence of the "first element". In addition, "one" or "a" and similar words do not indicate a quantity limitation, but rather indicate the existence of at least one, and "multiple" means not less than two.

[0052] In the description of the present application, the terms “including”, “having” indicate the existence of the described features, numbers, operations, elements and / or their combinations, but do not exclude the existence or addition of one or more other features, numbers, operations, elements and / or their combinations.

[0053] In the description of the present application, if there are similar terms such as "configured to" or "structured to", they can generally be interchanged with "having the ability to", "designed to", "for" or "capable of", depending on the context.

[0054] In the description of the present application, reference to "one embodiment" or "some embodiments" etc. means that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in the present specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0055] See also Figure 2 Combined with Figure 1 The embodiment of the present application provides a method for forming a reflective structure on a light guide plate substrate 7, the method comprising:

[0056] S201, providing a thermal transfer reflective film 100.

[0057] The thermal transfer reflective film 100 includes a base film layer 1, a release layer 2, a protective layer 3, a metal reflective layer 4 and a hot melt adhesive layer 5 which are sequentially stacked and combined along a first stacking direction DR1.

[0058] The base film layer 1 may be a PET film.

[0059] The main component of the release layer 2 is a release agent, and the release agent can be a resin wax release agent or a water wax release agent.

[0060] The main components of the protective layer 3 are acrylic resin and polyurethane resin. The solid content of acrylic resin in the protective layer 3 can be 1.3-1.7 g / m 2 The solid content of the polyurethane resin in the protective layer 3 may be 1.3 to 1.7 g / m 2 .

[0061] The main component of the metal reflective layer 4 is aluminum, which can be combined onto the protective layer 3 by evaporation. In other embodiments, the main component of the metal reflective layer 4 can also be other metals with reflective properties, such as silver, which can also be combined onto the protective layer 3 by evaporation.

[0062] The main component of the hot melt adhesive layer 5 is thermoplastic acrylic resin, which can show a certain degree of adhesion under the action of heat.

[0063] S202, providing a stacked body 200.

[0064] The stacked body 200 includes a plurality of light guide plate materials 6 stacked along a second stacking direction DR2, wherein the second stacking direction DR2 intersects (eg, is perpendicular to) the first stacking direction DR1. Figure 1 In the embodiment, each light guide plate material 6 includes a light guide plate substrate 7 and two protective films 8 which are laminated and bonded to the light guide plate substrate 7 on opposite sides along the second lamination direction DR2 in a releasable manner. The two protective films 8 are used to protect the two main surfaces of the light guide plate substrate 7 (corresponding to the light emitting surface 300c and the bottom surface 300b described later) to prevent the two main surfaces from being contaminated or mechanically damaged during the transfer or processing. The second side surface 7a of the light guide plate substrate 7 and the third side surface 8a of the protective film 8 define the first side surface 200a of the laminate 200.

[0065] In other embodiments, a portion of the light guide plate material 6 in the stacked body 200 may have only one protective film 8 , and the protective film 8 is laminated and bonded to only one side of the light guide plate substrate 7 along the second stacking direction DR2 in a releasable manner.

[0066] In practice, the operator can stack a plurality of light guide plate materials 6 of the same size together with the help of a mechanical device, and align the sides of the light guide plate materials 6, so as to obtain the aforementioned stacked body 200 in the shape of a rectangular parallelepiped as a whole. Since the structure and acquisition method of the light guide plate material 6 are well known, they will not be described in detail.

[0067] S203 , thermally and compressively bonding the thermal transfer reflective film 100 to the first side surface 200 a of the laminate 200 .

[0068] The operator can use the heat pressing device to heat press the heat transfer reflective film 100 to the first side 200a of the laminate 200. For example, the temperature of the heat transfer reflective film 100 can be increased by using the heating head of the heat pressing device. When the temperature of the heat transfer reflective film 100 reaches a set value so that the hot melt adhesive layer 5 thereof exhibits a certain degree of adhesion under the heat, the heat pressing device is used to apply pressure to the heat transfer reflective film 100 toward the first side 200a, and the pressure is maintained for a set time. In this way, the heat transfer reflective film 100 is bonded to the first side 200a of the laminate 200 by means of the hot melt adhesive layer 5 thereon, and the hot melt adhesive layer 5 is not only bonded to the second side 7a of the light guide plate substrate 7, but also bonded to the third side 8a of the protective film 8.

[0069] S204, tearing off the base film layer 1 so that a portion of the thermal transfer reflective film 100 follows the base film layer 1 and leaves from the first side surface 200a.

[0070] As mentioned above, after step S203 is completed, the hot melt adhesive layer 5 of the heat transfer reflective film 100 is bonded to both the second side surface 7a of the light guide plate substrate 7 and the third side surface 8a of the protective film 8. Based on this, if the bonding force between the hot melt adhesive layer 5 and the second side surface 7a (for convenience of description, referred to as the first bonding force) and the bonding force between the hot melt adhesive layer 5 and the third side surface 8a (for convenience of description, referred to as the second bonding force) are both relatively large, and both are greater than the bonding force between the base film layer 1 and the protective layer 3 provided by the release layer 2 (for convenience of description, referred to as the third bonding force), then in step S204, such an undesirable situation will occur: no matter at the second side surface 7a or the third side surface 8a, only the base film layer 1 (or a part or all of the release layer 2) will leave the heat transfer reflective film 100, so the metal reflective layer 4 will remain on the third side surface 8a of the protective film 8. However, it is undesirable to leave the metal reflective layer 4 on the protective film 8 , because the inventors have found that such a phenomenon easily leads to a significant decrease in the yield of the light guide plate 300 manufactured from the light guide plate substrate 7 .

[0071] For the above reasons, in this embodiment, the heat transfer reflective film 100 is optimally configured so that: the third bonding force is greater than the second bonding force but less than the first bonding force. In this way, after the step S204 is completed, at the second side 7a of the light guide plate substrate 7, at least the protective layer 3, the metal reflective layer 4 and the hot melt adhesive layer 5 are basically completely retained on the light guide plate substrate 7, and at the third side 8a of the protective film 8, since the third bonding force between the base film layer 1 and the protective layer 3 is greater than the second bonding force between the hot melt adhesive layer 5 and the third side 8a, the heat transfer reflective film 100 here almost completely leaves the third side 8a of the protective film 8. As a result, since there is almost no metal reflective layer 4 attached to the side of the protective film 8, the yield rate of the final light guide plate 300 can be easily improved.

[0072] In detail, the inventors found that when the solid content of the release agent in the release layer 2 is 0.2-0.4 g / m 2 The solid content of the thermoplastic acrylic resin in the hot melt adhesive layer 5 is 1.8 to 2.0 g / m 2 When the solid content of the release agent in the release layer 2 is higher than 0.4 g / m 2 When the release layer 2 is too thick, the release force, especially the release force between the release layer 2 and the base film layer 1, is too small. After step S204 is completed, the metal reflective layer 4 is likely to remain on the protective film 8. When the solid content of the release agent in the release layer 2 is less than 0.2 g / m 2 When the release force is too large, after step S204 is completed, the metal reflective layer 4 is easy to leave the light guide plate substrate 7, and cannot be well thermally transferred to the light guide plate substrate 7. When the solid content of the thermoplastic acrylic resin in the hot melt adhesive layer 5 is higher than 2.0 g / m 2 When the hot melt adhesive layer 5 is too thick, its structure is loose, the adhesion is weak, and it is easy to fall off. When the solid content of the thermoplastic acrylic resin in the hot melt adhesive layer 5 is less than 1.8 g / m 2 When the metal reflective layer 4 is not successfully thermally transferred to some areas of the second side surface 7a of the light guide plate substrate 7, the reason is that the second side surface 7a of the light guide plate substrate 7 obtained by the cutting process has a cutting line structure, and the second side surface 7a is uneven, and the cutting line depth can reach 2μm. Therefore, when the solid content of the thermoplastic acrylic resin in the hot melt adhesive layer 5 is lower than 1.8g / m 2 When the heat pressing device presses the heat transfer reflective film 100 against the second side surface 7a, the material of the hot melt adhesive layer 5 is difficult to contact the deep cutting lines after being melted, or cannot fully contact, resulting in poor heat transfer effect in the low-lying areas and easy falling off.

[0073] Please review Figure 1In order to conveniently tear off the base film layer 1 in step S204, in step S203, the reflective film 10 bonded to the first side 200a may have an extended portion 101 extending beyond the first side 200a, and then in the subsequent step S204, the extended portion 101 may be torn off to tear off the base film layer 1, thereby causing a portion of the reflective film 10 (especially the portion of the thermal transfer reflective film 100 at the third side 8a) to follow the base film layer 1 and leave from the first side 200a.

[0074] exist Figure 1 In the embodiment, each of the light guide plate substrate 7 and the protective film 8 is in a rectangular shape with four sides. Figure 1 The laminate 200 in the embodiment has four side surfaces in total, and the four side surfaces of the laminate 200 are arranged around the second lamination direction DR2. Depending on the use requirements, in the aforementioned step S203, two heat transfer reflective films 100 can be heat-pressed and bonded to two side surfaces of the laminate 200 simultaneously or successively (that is, the two side surfaces are both the aforementioned first side surfaces 200a, for example, the two first side surfaces 200a can be Figure 1 The light guide plate substrate 7 is provided with a reflective structure (reflective film 10) on two sides thereof (one side facing the reader and the other side facing away from the reader), or three heat transfer reflective films 100 are heat-pressed and bonded to three sides of the stack 200 simultaneously or successively, or only one heat transfer reflective film 100 is heat-pressed and bonded to only one side of the stack 200.

[0075] After the processing of steps S201 to S204, a reflective structure is formed on the second side surface 7a of each light guide plate substrate 7 in the stacked body 200, and the reflective structure at least includes a hot melt adhesive layer 5, a metal reflective layer 4 and a protective layer 3. The light guide plate substrate 7 with the reflective structure is further processed by relevant treatment (for example, hot stamping or UV stamping is performed on one main surface of the light guide plate substrate 7 to form a light guide microstructure 9) to obtain Figure 3 to Figure 4 The light guide plate 300 is shown.

[0076] Next, combine Figures 3 to 6 , a light guide plate 300 made by using the light guide plate substrate 7 processed through the aforementioned steps S201 to S204 as a raw material is introduced in detail.

[0077] The light guide plate 300 is in the shape of a rectangular thin plate, and has a light incident surface 300a, a light emitting surface 300c, a bottom surface 300b, and a plurality of side surfaces 300d, 300e, and 300f.

[0078] The light emitting surface 300c and the bottom surface 300b are arranged opposite to each other in the thickness direction of the light guide plate 300, and a plurality of light guide microstructures 9 are formed on the bottom surface 300b. The light guide microstructures 9 can guide (e.g. reflect) the light emitted thereto to obtain the desired light emission quality at the light emitting surface 300c of the light guide plate 300.

[0079] The light incident surface 300a is connected to the light emitting surface 300c and the bottom surface 300b on one side thereof, and is formed into a narrow long rectangle. The light guide plate 300 has three side surfaces 300d, 300e, and 300f, which respectively connect the light emitting surface 300c and the bottom surface 300b on the other three sides thereof, wherein the side surface 300e is opposite to the light incident surface 300a and is the far light end side surface of the light guide plate 300.

[0080] exist Figure 3 In the embodiment, a reflective film 10 (corresponding to the reflective structure on the light guide plate substrate 7) is formed on each side surface 300d, 300e, and 300f of the light guide plate 300 based on the thermal transfer method of the aforementioned steps S201 to S204, which reflects light toward the inside of the light guide plate 300. That is, the reflective film 10 is obtained based on the method of the aforementioned steps S201 to S204.

[0081] The light guide plate 300 may be applied to Figure 6 In the edge-entry backlight module shown. In the edge-entry backlight module, the LED light source 11 is arranged on the light incident surface 300a side of the light guide plate 300. The LED light source 11 can generate light through the light incident surface 300a under the drive of electricity and enter the interior of the light guide plate 300, and part of the light may be guided to the side surfaces 300d, 300e, and 300f and intended to be output from the side surfaces 300d, 300e, and 300f. As a result, the effective light output from the light output surface 300c is reduced, resulting in a decrease in the light output efficiency of the light guide plate 300. Advantageously, in this embodiment, a reflective film 10 for reflecting light toward the interior of the light guide plate 300 is formed on the sides 300d, 300e, and 300f of the light guide plate 300. The reflective film 10 can reflect the light to be output from the sides 300d, 300e, and 300f into the interior of the light guide plate 300, thereby increasing the amount of light output from the light output surface 300c and improving the light output efficiency of the light guide plate 300.

[0082] Obviously, the reflective film 10 may be formed on only one of the three side surfaces 300d, 300e, and 300f (for example, the side surface 300e), which can also improve the light extraction efficiency of the light guide plate 300.

[0083] See also Figure 5In combination with the above description, the reflective film 10 of each side 300d, 300e, 300f includes at least a hot melt adhesive layer 5, a metal reflective layer 4 and a protective layer 3 which are sequentially laminated and combined in a direction away from the corresponding side 300d, 300e, 300f. The protective layer 3 can protect the metal reflective layer 4 inside from being damaged by foreign objects or chemically oxidized.

[0084] In some embodiments, the metal reflective layer 4 includes metal (eg, aluminum or silver) and silicon dioxide bonded to the protective layer 3 by evaporation, and the sum of the masses of the metal and silicon dioxide may account for more than 99% (eg, 100%) of the total mass of the metal reflective layer 4 .

[0085] The inventors have found that when a certain amount of silicon dioxide is added to the metal reflective layer 4, especially when the mass ratio of silicon dioxide to metal is less than 5:100 (i.e., 0 to 5:100, but not 0), and especially when the mass ratio of silicon dioxide to metal is further preferably 2 to 4:100, the optical quality of the light guide plate substrate 7 and the light guide plate 300 can be significantly improved. For this, please refer to Figure 7 and Figure 8 .

[0086] Figure 7 The figure shows the optical quality of the far light end of the light guide plate 300 when light is incident from the light incident surface 300a when the metal reflective layer 4 is entirely made of aluminum (more than 99.99% pure aluminum). It can be seen that there is an undesirable bright band near the side opposite to the light incident surface 300a (far light end), and the optical quality of the light guide plate 300 is poor.

[0087] Figure 8 The metal reflective layer 4 is formed of aluminum and silicon dioxide (the mass ratio of silicon dioxide to aluminum is 3.53:100), and the other conditions are the same as those of FIG. Figure 7 Under the same conditions, when light is incident from the light incident surface 300a, the light quality at the far end of the light guide plate 300 is shown as follows: the bright band disappears, and the optical quality of the light guide plate 300 is significantly improved.

[0088] exist Figure 7 and Figure 8 In the figure, the lower side of the light guide plate 300, that is, the side close to the tester's hand, corresponds to Figure 3 The side edge 300e in the middle corresponds to the right side edge of the light guide plate 300. Figure 3 The left side of the light guide plate 300 corresponds to the side 300d in Figure 3 Side 300f in. Compare Figure 7 and Figure 8It can be seen that by adding a specified amount of silicon dioxide molecules to the metal reflective layer 4, under the premise of ensuring the reflectivity of the reflective film 10, the reflection has both the characteristics of mirror reflection and Gaussian scattering caused by the scattering of silicon dioxide molecules, thereby reducing the risk of bright lines appearing at specific angles or specific positions of the light guide plate 300 due to only mirror reflection of the reflective film 10, and the scattered light makes the light output of the far light end of the light guide plate 300 more uniform, which is conducive to solving the dark corners and the overall darkening of the far light end of the conventional light guide plate 300, thereby improving the optical taste.

[0089] The inventor believes that Figure 8 The corresponding light guide plate 300 has the above-mentioned excellent optical quality. Figure 7 The optical quality of the middle light guide plate 300 is poor, and the main reasons are: Figure 7 The metal reflective layer 4 formed by pure aluminum has a mirror reflective surface. When light irradiates the aluminum layer surface with a mirror structure, it is mirror reflected. After adding silicon dioxide molecules to the metal aluminum reflective layer, when light irradiates the silicon dioxide molecules in the reflective layer, scattering occurs, breaking up the light. Experiments have found that when the mass ratio of silicon dioxide to aluminum is below 5:100, after light irradiates the metal reflective layer 4, Gaussian scattering can occur under the combined action of the aluminum layer surface and silicon dioxide molecules, such as Fig. 9 shown.

[0090] Fig. 9 The figure is a schematic diagram of Gaussian scattering of a light ray after passing through the metal reflective layer 4 doped with silicon dioxide molecules. Most of the energy in the scattered light is concentrated in the envelope shown by the dotted line in the figure. The axis of the light envelope and the incident light ray satisfy the principle of specular reflection (the reflection angle is equal to the incident angle). In the figure, P(0) is the intensity of the light in the direction of specular reflection, and P(θ) is the intensity of the scattered light at an angle of θ. P(0) and P(θ) have a scattering energy distribution that changes according to the following equation:

[0091]

[0092] Wherein, θ is the angle of deviation from the mirror reflection optical axis; σ is the Gaussian diffusion angle.

[0093] It can be seen from the above equation that after Gaussian diffusion, the light is directed to the metal reflective layer 4, and the light reflected by the mirror is scattered, which disperses the energy distribution of the light to a certain extent, and breaks up the light, thereby reducing the risk of bright lines appearing at a specific angle or a specific position on the light guide plate 300. When the Gaussian diffusion angle σ≤15°, and more preferably σ≤10°, the light guide plate 300 can not only eliminate bright lines, bright spots, etc. caused by mirror reflection, but also make the light at the far end of the light guide plate 300 uniform and maintain a high brightness. Accordingly, the inventors found that when the mass ratio of silicon dioxide to aluminum (or other metals, such as silver) in the metal reflective layer 4 is less than 5:100, the Gaussian diffusion angle σ of the metal reflective layer 4 can be easily made ≤15°; in particular, when the mass ratio of silicon dioxide to aluminum (or other metals, such as silver) in the metal reflective layer 4 is between 2 and 4:100, the Gaussian diffusion angle σ of the metal reflective layer 4 can be easily made ≤10°. Based on the above description, the embodiment of the present application further provides a thermal transfer reflective film 100, which includes a base film layer 1, a release layer 2, a protective layer 3, a metal reflective layer 4 and a hot melt adhesive layer 5 which are sequentially stacked and bonded along a first stacking direction DR1, the hot melt adhesive layer 5 is configured to be bonded to the light guide plate substrate 7 under the action of heat, and the base film layer 1 is configured to be able to be separated from the thermal transfer reflective film 100 when the hot melt adhesive layer 5 is bonded to the light guide plate substrate 7. That is, the thermal transfer reflective film 100 can be bonded to the light guide plate substrate 7 with the help of the hot melt adhesive layer 5 thereon, and when the thermal transfer reflective film 100 is bonded to the light guide plate substrate 7, the base film layer 1 can be separated from the thermal transfer reflective film 100, based on which, after subsequent processing, the final product can be obtained. Figure 3 and Figure 4 The light guide plate 300 in the embodiment of the present invention.

[0094] More specifically, the heat transfer reflective film 100 is used to be attached to the first side 200a of the stacked body 200 to transfer the metal reflective layer 4 to the second side 7a of the light guide plate substrate 7, wherein the stacked body 200 includes a plurality of light guide plate sheets 6 stacked along a second stacking direction DR2 intersecting the first stacking direction DR1, each light guide plate sheet 6 includes a light guide plate substrate 7 and a protective film 8 that is peelably laminated and bonded to at least one side of the light guide plate substrate 7 along the second stacking direction DR2, and the second side 7a and the third side 8a of the protective film 8 define the first side 200a. The hot melt adhesive layer 5 is configured to: bond to the second side 7a of the light guide plate substrate 7 under the action of heat and have a first bonding force, bond to the third side 8a of the protective film 8 and have a second bonding force, and the bonding force provided by the release layer 2 between the base film layer 1 and the protective layer 3 is greater than the second bonding force but less than the first bonding force.

Claims

1. A thermal transfer reflective film, characterized in that: It includes a base film layer, a release layer, a protective layer, a metal reflective layer and a hot melt adhesive layer which are sequentially stacked and bonded along a first stacking direction, wherein the hot melt adhesive layer is configured to be bonded to a light guide plate substrate under the action of heat, and the base film layer is configured to be able to be separated from the thermal transfer reflective film when the hot melt adhesive layer is bonded to the light guide plate substrate.

2. The thermal transfer reflective film according to claim 1, characterized in that: The metal reflective layer comprises a metal and silicon dioxide bonded to the protective layer by evaporation, and the mass ratio of the silicon dioxide to the metal is less than 5:100; Preferably, the mass ratio of the silicon dioxide to the metal is 2 to 4:

100.

3. The thermal transfer reflective film according to claim 2, characterized in that: The metal is silver or aluminum.

4. The thermal transfer reflective film according to claim 1, 2 or 3, characterized in that: The thermal transfer reflective film is used to be attached to the first side of the stacked body to transfer the metal reflective layer to the second side of the light guide plate substrate, wherein the stacked body includes a plurality of light guide plate sheets stacked along a second stacking direction intersecting the first stacking direction, each of the light guide plate sheets includes one light guide plate substrate and a protective film that is peelably laminated and bonded to at least one side of the light guide plate substrate along the second stacking direction, and the second side and the third side of the protective film define the first side; The hot melt adhesive layer is configured as follows: under the action of the heat, it is bonded to the second side of the light guide plate substrate and has a first bonding force, and is bonded to the third side of the protective film and has a second bonding force, and the bonding force between the base film layer and the protective layer provided by the release layer is greater than the second bonding force but less than the first bonding force.

5. The thermal transfer reflective film according to claim 4, characterized in that: The release layer is a thermal release layer whose release force with the base film layer is reduced under the action of heat.

6. The thermal transfer reflective film according to claim 4, characterized in that: The solid content of the release agent in the release layer is 0.2 to 0.4 g / m 2 The solid content of the thermoplastic acrylic resin in the hot melt adhesive layer is 1.8 to 2.0 g / m 2 .

7. A light guide plate comprising a light emitting surface, a bottom surface opposite to the light emitting surface, a light incident surface respectively connecting the light emitting surface and the bottom surface, and a plurality of side surfaces, wherein: A reflective film for reflecting light toward the inside of the light guide plate is formed on at least one of the plurality of side surfaces by thermal transfer.

8. The light guide plate according to claim 7, characterized in that: The reflective film comprises a hot melt adhesive layer, a metal reflective layer and a protective layer which are sequentially stacked and bonded in a direction away from the side surface, wherein the metal reflective layer comprises a metal and silicon dioxide bonded to the protective layer by evaporation, and the mass ratio of the silicon dioxide to the metal is less than 5:100; Preferably, the mass ratio of the silicon dioxide to the metal is 2 to 4:

100.

9. The thermal transfer reflective film according to claim 8, characterized in that: The metal is silver or aluminum.

10. The light guide plate according to claim 8, characterized in that: The solid content of the thermoplastic acrylic resin in the hot melt adhesive layer is 1.8 to 2.0 g / m 2 .

11. A method for forming a reflective structure on a light guide plate substrate, characterized in that: include: Providing a thermal transfer reflective film as described in any one of claims 4 to 6; providing the laminate; Thermally pressing the thermal transfer reflective film to the first side of the laminate; The base film layer is torn off so that a portion of the thermal transfer reflective film follows the base film layer and leaves from the first side.

12. The method according to claim 11, characterized in that The step of hot-pressing and bonding the heat transfer reflective film to the first side of the laminate comprises: Bonding the heat transfer reflective film to the first side of the laminate by heat compression, wherein the reflective film bonded to the first side has a protruding portion extending beyond the first side; The step of tearing the base film layer so that a portion of the reflective film follows the base film layer and leaves from the first side surface comprises: The protruding portion is torn to tear the base film layer, thereby causing a portion of the reflective film to follow the base film layer and leave from the first side.

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