TW201302351A - Light guide plate equipped with protective film - Google Patents

Abstract

A light guide plate equipped with a protective film, provided with a light guide plate having a surface on which convex portions have been formed, and a protective film bonded to the surface on which the convex portions have been formed. Subsequent to the bonding of the protective film to the light guide plate heated to 40 C, the peel strength between the light guide plate and the protective film is 0.1-0.8 N/25 mm. Subsequent to the bonding of the protective film to the light guide plate heated to 70 C, the peel strength between the light guide plate and the protective film is 0.1-0.8 N/25 mm.

Description

Light guide plate with protective film

The present invention relates to a light guide plate with a protective film and a protective film therefor.

A light guide plate with a protective film attached to a surface of an acrylic resin sheet used as a light guide plate is known (for example, see Patent Document 1). The surface of the acrylic resin sheet is flat.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. Hei 8-170056

In recent years, a light guide plate (a so-called shape light guide plate) having a surface on which a convex portion is formed has been attracting attention. The inventors of the present invention have studied a technique of bonding a protective film to a surface of a light guide plate on which a convex portion is formed. However, it is clear that depending on the characteristics of the protective film, when the protective film is bonded to the light guide plate and then cut to a specific size, the end portion of the protective film is peeled off from the light guide plate. Further, it is also clear that, depending on the characteristics of the protective film, when the protective film is peeled off from the light guide plate, it is difficult to peel off at once without applying excessive force. These problems do not occur when the surface of the light guide plate is flat, but are caused when a convex portion is formed on the surface of the light guide plate.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive property and peeling between a surface on which a convex portion of a light guide plate is formed and a protective film. A light guide plate with a protective film excellent in characteristics and a protective film therefor.

In order to solve the above problems, a light guide plate with a protective film according to an aspect of the present invention includes: a light guide plate having a surface on which a convex portion is formed; and a protective film attached to the surface on which the convex portion is formed; The peeling strength between the light guide plate and the protective film after the protective film is bonded to the light guide plate heated to 40° C. is 0.1 to 0.8 N/25 mm, and the protective film is bonded to a temperature of 70° C. The peeling strength between the light guide plate and the protective film after the light guide plate is 0.1 to 0.8 N/25 mm.

In the protective film having a peeling strength of less than 0.1 N/25 mm between the light guide plate and the protective film, when the protective film and the light guide plate are cut, the end portion of the protective film tends to be peeled off from the light guide plate. On the other hand, in the light guide plate with the protective film including the protective film having the peeling strength of 0.1 N/25 mm or more, even if the light guide plate to which the protective film is attached is cut, the end portion of the protective film can be suppressed from the light guide plate. Stripped. Therefore, a light guide plate with a protective film excellent in adhesion characteristics between the surface on which the convex portion is formed and the protective film of the light guide plate can be obtained.

In the protective film in which the peeling strength between the light guide plate and the protective film exceeds 0.8 N/25 mm, when the protective film is peeled off from the light guide plate, it is difficult to peel off once without applying excessive force. On the other hand, in the light guide plate with the protective film including the protective film having the peeling strength of 0.8 N/25 mm or less, when the protective film is peeled off from the light guide plate, the protective film can be applied at one time without applying excessive force. Stripped. Therefore, a light guide plate with a protective film excellent in peeling characteristics between the surface on which the convex portion is formed and the protective film of the light guide plate can be obtained.

After the protective film is attached to the above-mentioned light guide plate heated to 40 ° C, After the heat treatment at 70 ° C for 40 minutes, the peeling strength between the light guide plate and the protective film is 0.1 to 0.8 N / 25 mm, and after the protective film is bonded to the light guide plate heated to 70 ° C, 70 The peeling strength between the light guide plate and the protective film after the heat treatment for 40 minutes at ° C may be 0.1 to 0.8 N/25 mm.

In this case, even if the light guide plate with the protective film is heat-treated at 70 ° C for 40 minutes in the subsequent step, the adhesion property and the peeling property between the surface on which the convex portion of the light guide plate is formed and the protective film can be obtained. A light guide plate with a protective film.

A protective film according to an aspect of the present invention is used for the above-mentioned light guide plate with a protective film.

According to the present invention, there is provided a light guide plate with a protective film and a protective film therefor, which are excellent in adhesion characteristics and peeling characteristics between a surface of a light guide plate in which a convex portion is formed and a protective film.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and the repeated description is omitted.

(Manufacturing device for light guide plate with protective film)

Fig. 1 is a schematic block diagram showing a manufacturing apparatus of a light guide plate with a protective film according to an embodiment. The apparatus 100 for manufacturing a light guide plate with a protective film shown in Fig. 1 is a device which can be used for manufacturing a light guide plate with a protective film of the present embodiment. A manufacturing apparatus 100 for a light guide plate with a protective film includes a light guide plate manufacturing apparatus 50, a protective film bonding apparatus 70, and a cutting apparatus 80.

The light guide plate manufacturing apparatus 50 includes a mold 51 that continuously extrudes a resin in a heated molten state to obtain a continuous resin sheet 60, and a first pressing roll 52A and a second pressing roll 52B, which are self-thickness directions. The continuous resin sheet 60 extruded from the mold 51 is extruded on both sides. The light guide plate manufacturing apparatus 50 may also include a pre-pressing roll 52D in the preceding stage of the first pressing roll 52A as needed. The pre-pressing roller 52D has the same configuration as the first pressing roller 52A. The pre-pressing roll 52D presses the continuous resin sheet 60 between the pre-pressing roll 52D and the first pressing roll 52A. The light guide plate manufacturing apparatus 50 includes a resin input port 57 for inputting a resin which is a raw material, and an extruder 58 for extruding a resin which is supplied from the resin inlet 57.

The first pressing roller 52A and the second pressing roller 52B are configured to be rotatable about mutually parallel rotation axes. The first pressing roll 52A and the second pressing roll 52B are arranged apart from each other in the thickness direction of the continuous resin sheet 60, and the interval between the peripheral surfaces of the continuous resin sheets 60 is set according to the thickness of the continuous resin sheet 60. As shown in FIG. 3, a transfer mold 53 corresponding to the uneven shape transferred to the continuous resin sheet 60 is formed on the circumferential surface of the second pressing roll 52B. The details are described below. The second pressing roller 52B corresponds to a shape roller. The second pressing roller 52B including the transfer mold 53 is also referred to as a transfer roller. The light guide plate 30 is manufactured in this manner.

The protective film bonding apparatus 70 includes a first pressing roller 72A and a second pressing roller 72B, and the light guiding plate 30 supplied from the manufacturing apparatus 50 of the light guiding plate is pressed from both sides in the thickness direction and bonded thereto. The protective films 40 and 42 on both sides, and the protective film rolls 72C and 72D are wound around the protective films 40 and 42, respectively. The protective film 40 is supplied from the protective film roll 72C to the first squeeze roll 72A. The protective film 42 is supplied from the protective film roll 72D to the second squeeze roll 72B. The protective film is also called a masking film. Guarantee The protective film 42 may not be attached to the light guide plate 30. In this case, the protective film roll 72D is not required.

The dicing device 80 cuts the light guide plate 30 of the protective films 40 and 42 to which the bonding device 70 bonded with the self-protecting film is attached to a specific size. In this way, the light guide plate 90 with the protective film is manufactured.

(light guide plate)

Fig. 2 is a perspective view schematically showing the configuration of a light guide plate. A portion of the light guide plate 30 is shown in FIG. The light guide plate 30 can be used as a light guide plate of a surface light source device (for example, a backlight device) mounted on a transmissive image display device (for example, a liquid crystal display). The surface light source device includes a side light type surface light source device having a light source such as an LED (Light Emitting Diode) disposed on the side surface 33 of the light guide plate 30, and is self-guided. Light incident on the side surface 33 of the light plate 30 is emitted to the front side.

Normally, the back surface 32 of the light guide plate 30 (the surface opposite to the surface 31) is subjected to reflection processing for diffusing and reflecting light incident from the side surface 33. Regarding printing performed as a reflection process, inkjet printing is mentioned in addition to screen printing. Alternatively, as a method of performing the reflection processing, a method of imparting point-like irregularities by laser irradiation instead of printing may be mentioned.

A plurality of convex portions 35 are formed on the surface 31 of the light guide plate 30, and the plurality of convex portions 35 extend in the first direction (X-axis direction) and are arranged in parallel in the second direction orthogonal to the first direction ( Y-axis direction). The uneven shape including the convex portion 35 formed on the surface 31 is formed by the following transfer step.

The light guide plate 30 is formed of, for example, a translucent resin. The refractive index of the light transmissive resin is usually from 1.49 to 1.59. As the light transmissive resin used for the light guide plate 30, A thermoplastic resin which is in a molten state by heating can also be used. For example, a methacrylic resin (acrylic resin), a styrene resin, a carbonate resin, a cycloolefin resin, an MS (Methyl-methacrylate Styrene) resin (a copolymer of acrylic acid and styrene), or the like can be used. Examples of the methacrylic resin include a copolymer of methyl methacrylate and methyl acrylate.

As the light-transmitting resin used for the light guide plate 30, a thermosetting resin which is cured by heating can also be used. An additive such as a light diffusing agent, an ultraviolet absorber, a heat stabilizer, or an antistatic agent may be added to the light transmissive resin used for the light guide plate 30.

(transfer mode)

Fig. 3 is a cross-sectional view schematically showing a concave portion formed in a transfer mold and a convex portion formed on the light guide plate. One portion of the transfer mold 53 and the light guide plate 30 is shown in FIG. A plurality of concave portions 53a provided on the surface of the second pressing roller 52B (shape roller) are formed in the transfer mold 53. The plurality of concave portions 53a correspond to the plurality of convex portions 35. For example, the concave portion 53a is continuously formed in the circumferential groove of the second pressing roller 52B (shape roller). The distance P between the plurality of concave portions 53a is usually 30 μm or more, and preferably 50 μm or more. The pitch P is, for example, 30 μm to 800 μm. The depth D of the concave portion 53a is, for example, 30 μm to 500 μm. The pitch P refers to the distance between the centers (bottoms of each other) in the Y-axis direction of the adjacent concave portions 53a. The depth D of the concave portion 53a means the distance from the opening surface of the concave portion 53a to the bottom of the concave portion 53a.

The cross-sectional shape of the concave portion 53a of the transfer mold 53 includes a semicircular shape, a semi-elliptical shape, and the like. The cross-sectional shape of the concave portion 53a may be a V-shaped shape having an acute corner portion corresponding to the 稜鏡 shape.

As a method of producing the transfer mold 53, for example, the following method can be mentioned. First, a surface of a metal roll including stainless steel or steel is subjected to plating treatment such as chrome plating, copper plating, nickel plating, or nickel-phosphorus plating. Thereafter, the plated surface is subjected to removal processing, laser processing, or chemical etching using a diamond turning tool or a metal grindstone to process the shape. However, the method of producing the transfer mold 53 is not particularly limited to these methods.

After the transfer mold 53 is formed on the surface of the transfer roller, for example, plating treatment such as chrome plating, copper plating, nickel plating, or nickel-phosphorus plating may be performed without impairing the accuracy of the surface shape.

(Light guide plate with protective film)

Fig. 4 is a cross-sectional view showing a light guide plate with a protective film according to an embodiment. A portion of the light guide plate 90 with a protective film is shown in FIG. The light guide plate 90 with a protective film shown in FIG. 4 includes a light guide plate 30 having a surface 31 on which the convex portion 35 is formed, and a protective film 40 attached to the surface 31 on which the convex portion 35 is formed. In the light guide plate 90 with a protective film, a gap is formed between the protective film 40 and the light guide plate 30 between the adjacent convex portions 35. The light guide plate 90 with the protective film may further include a protective film 42 attached to the back surface 32 of the light guide plate 30.

The protective films 40 and 42 include, for example, a substrate and an adhesive layer formed on the substrate, and the adhesive layer is disposed between the substrate and the light guide plate 30. The protective film 40 protects the surface 31 of the light guide plate 30 and peels off when the light guide plate 30 is used. The protective film 42 protects the back surface 32 of the light guide plate 30 and peels off when the light guide plate 30 is used. The substrate of the protective film 40 contains, for example, a polymer such as polypropylene. The protective film 42 may have the same configuration as the protective film 40, or may have a different configuration.

The protective film 40 is attached to the light guide plate 30 after being heated to 40 ° C. The peel strength with the protective film 40 is 0.1 to 0.8 N/25 mm. Similarly, the peeling strength between the light guide plate 30 and the protective film 40 after the protective film 40 is bonded to the light guide plate 30 heated to 70 ° C is 0.1 to 0.8 N/25 mm.

Peel strength is a value obtained by measuring a sample having a width of 25 mm in accordance with JIS Z0237 and peeling the protective film in a 180° direction at a tensile speed of 300 mm/min using an autostereograph.

In the protective film having a peeling strength of less than 0.1 N/25 mm between the light guide plate and the protective film, when the protective film and the light guide plate are cut, the end portion of the protective film tends to be peeled off from the light guide plate. On the other hand, in the light guide plate 90 including the protective film of the protective film 40 having the peeling strength of 0.1 N/25 mm or more, even if the protective film 40 and the light guide plate 30 are cut, the end portion of the protective film 40 can be suppressed. The light guide plate 30 is peeled off. Therefore, the light guide plate 90 with the protective film excellent in the adhesion property between the surface 31 of the light guide plate 30 in which the convex portion 35 is formed and the protective film 40 can be obtained.

In the protective film in which the peeling strength between the light guide plate and the protective film exceeds 0.8 N/25 mm, when the protective film is peeled off from the light guide plate, it is difficult to peel off once without applying excessive force. On the other hand, in the light guide plate 90 including the protective film of the protective film 40 having the above peeling strength of 0.8 N/25 mm or less, when the protective film 40 is peeled off from the light guide plate 30, the excessive force can be applied once. The protective film 40 is peeled off sexually. Therefore, the light guide plate 90 with the protective film excellent in the peeling property between the surface 31 of the light-guide plate 30 in which the convex part 35 and the protective film 40 are formed is obtained.

After the protective film 40 is bonded to the light guide plate 30 heated to 40° C., the peeling between the light guide plate 30 and the protective film 40 after heat treatment at 70° C. for 40 minutes is performed. The strength can also be 0.1~0.8 N/25 mm. After the protective film 40 is bonded to the light guide plate 30 heated to 70° C., the peeling strength between the light guide plate 30 and the protective film 40 after heat treatment at 70° C. for 40 minutes may be 0.1 to 0.8 N/25 mm. . In this case, even if the light guide plate 90 with the protective film is heat-treated at 70 ° C for 40 minutes in the subsequent step, the deterioration of the light guide plate 30 can be suppressed, and the surface 31 of the light guide plate 30 on which the convex portion 35 is formed can be obtained and protected. The light guide plate 90 with a protective film excellent in adhesion characteristics and peeling characteristics between the films 40. The heat treatment in the subsequent step is, for example, a heat treatment for removing the solvent contained in the ink to be printed when the back surface 32 of the light guide plate 30 is printed as a reflection process.

(Manufacturing method of light guide plate with protective film)

Fig. 5 is a flow chart showing the procedure of a method of manufacturing a light guide plate with a protective film according to an embodiment. The method for producing a light guide plate with a protective film according to the present embodiment can be carried out, for example, by using the light guide plate manufacturing apparatus 100 with a protective film shown in Fig. 1 . As shown in FIG. 1 and FIG. 5, the method for producing a light guide plate with a protective film according to the present embodiment includes a sheet manufacturing step (S1) in which a resin in a heated and molten state is continuously extruded from a mold 51 to form a continuous shape. Resin sheet 60; transfer step (S2) of transferring transfer mold 53 to continuous resin sheet 60 using second nip roll 52B (shape roll) having a peripheral surface on which transfer mold 53 is formed a surface; a bonding step (S3) for bonding the protective film 40 to the surface 31 of the light guide plate 30 formed with the convex portion 35 obtained by the transfer step (S2); and a cutting step (S4), It cuts the light guide plate 30 to which the protective film 40 is attached.

(sheet manufacturing step)

In the sheet manufacturing step, the resin is connected from the mold 51 in a heated and molten state. The continuous resin sheet 60 is continuously extruded. The resin is a thermoplastic resin which is in a molten state by heating.

As the mold 51 in which the resin is continuously extruded in a heated and molten state, for example, a T-die made of a metal similar to that of a user in a usual extrusion molding method can be used. When the resin is extruded from the mold 51 in a heat-melted state, the extruder 58 is used in the same manner as the usual extrusion molding method. The extruder 58 can be a single screw extruder or a twin screw extruder. The resin is heated in the extruder 58, and is sent to the mold 51 in a molten state and extruded. The resin extruded from the mold 51 is continuously extruded into a sheet form to form a continuous resin sheet 60. The thickness of the continuous resin sheet 60 is, for example, 1.0 mm or more and 4.5 mm or less.

(transfer step)

The transfer step (S2) includes an extrusion step of being manufactured by the sheet manufacturing step (S1) by sandwiching the first pressing roller 52A (squeeze roller) and the second pressing roller 52B (shape roller). The continuous resin sheet 60 is pressed, and the conveying step is performed by holding the continuous resin sheet 60 extruded in the pressing step in close contact with the circumferential surface of the second pressing roll 52B, and a peeling step. The continuous resin sheet 60 conveyed in the conveyance step is peeled off from the circumferential surface (transfer mold 53) of the second squeeze roll 52B.

(extrusion step)

The continuous resin sheet 60 obtained in the sheet manufacturing step (S1) is subjected to a pressing step, and the first pressing roll 52A and the second pressing roll 52B are used from the thickness direction of the sheet as shown in FIG. Both sides are simultaneously clamped and squeezed.

At this time, the surface temperature of the continuous resin sheet 60 immediately before the contact with the second pressing roll 52B is, for example, a temperature in the range of 180 ° C to 250 ° C. surface temperature For example, it can be adjusted according to the change of the set temperature of the extruder 58, and the change of the set temperature of the mold 51. The surface temperature of the continuous resin sheet 60 can be measured, for example, using an infrared thermometer.

In the pressing step, the shape of the transfer mold 53 formed on the surface of the second pressing roller 52B (shape roller) is transferred to the continuous resin sheet 60. The transfer mold 53 included in the surface of the transfer roller is pressed against the surface of the continuous resin sheet 60. As a result, the reverse transformation of the surface shape of the transfer mold 53 is transferred to the continuous resin sheet 60.

As the first and second pressing rolls 52A and 52B, a metal roll including a metal such as stainless steel or steel is usually used, and its diameter is usually 100 mm to 500 mm. When a metal roll is used as the first and second pressing rolls 52A and 52B, plating treatment such as chrome plating, copper plating, nickel plating, or nickel-phosphorus plating may be applied to the surface. The surface (peripheral surface) of the first pressing roller 52A may be a mirror surface, or may be a transfer surface on which irregularities such as embossing are applied.

A pre-extrusion pre-compression step can also be carried out prior to the extrusion step. In the pre-pressing step, the continuous resin sheet 60 manufactured by the sheet manufacturing step (S1) is sandwiched between the pre-pressing roller 52D and the first pressing roller 52A, whereby the continuous resin sheet 60 is preliminarily pressed. The extruded continuous resin sheet 60 is conveyed while being in close contact with the circumferential surface of the first squeeze roll 52A. Thereafter, the pressing step is performed by the first and second pressing rolls 52A and 52B.

(transfer step)

The transport step is a step of transporting the continuous resin sheet 60 in accordance with the rotation of the second squeeze roll 52B while the continuous resin sheet 60 is in close contact with the circumferential surface of the second squeeze roll 52B.

(peeling step)

The peeling step is a step of peeling the continuous resin sheet 60 from the circumferential surface of the second pressing roll 52B.

The light guide plate 30 is manufactured by the above steps. The temperature of the light guide plate 30 immediately after the stripping step is, for example, 90 ° C or higher.

(Fitting step)

In the bonding step (S3), as shown in FIG. 1, the protective films 40 and 42 are bonded to the light guide plate 30 by using a bonding device 70 for a protective film. The light guide plate 30 and the protective films 40 and 42 are simultaneously sandwiched and pressed from both sides in the thickness direction of the light guide plate 30 by the first pressing roll 72A and the second pressing roll 72B. By the rotation of the first pressing roller 72A and the second pressing roller 72B, the protective film 40 is bonded to the surface 31 of the light guide plate 30, and the protective film 42 is bonded to the back surface 32 of the light guide plate 30. The protective film 40 is supplied to the first pressing roller 72A by rotating the protective film roll 72C, and is bonded to the light guide plate 30 in a state of being in close contact with the circumferential surface of the first pressing roller 72A. The protective film 42 is supplied to the second pressing roll 72B by rotating the protective film roll 72D, and is bonded to the light guide plate 30 in a state of being in close contact with the circumferential surface of the second pressing roll 72B.

The temperature of the light guide plate 30 at the time of bonding can be controlled by adjusting the temperature of the light guide plate 30 directly after the peeling step, and can be 40 to 70 ° C or 50 to 60 ° C. The temperature of the light guide plate 30 at the time of bonding can be adjusted, for example, by the distance between the manufacturing apparatus 50 of the light guide plate and the bonding apparatus 70 of the protective film.

(cutting step)

In the cutting step (S4), as shown in FIG. 1, the light guide plate 30 to which the protective films 40, 42 are bonded is cut into a specific size using a cutting device 80. In this way The light guide plate 90 with the protective film shown in Fig. 4 was obtained.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments.

(Example)

Hereinafter, the present invention will be specifically described based on examples, reference examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)

The protective film was bonded to a light guide plate previously heated to 40 ° C using a manufacturing apparatus of a light guide plate with a protective film as shown in FIG. 1 . As the light guide plate, a shape light guide plate having a surface on which a convex portion is formed is used. A protective film is bonded to the surface on which the convex portion is formed. As the protective film, a polypropylene film (trade name: L7330, manufactured by Hitachi Chemical Co., Ltd.) can be used. Thereafter, the protective film and the light guide plate were cut into a width of 25 mm × a length of 300 mm, and a light guide plate with a protective film was produced.

The conductive film is preheated to 70 ° C instead of 40 ° C. Similarly, the protective film is attached to the light guide plate, and the protective film and the light guide plate are cut into a width of 25 mm × a length of 300 mm to prepare a protective film. Light board.

For the two kinds of light guide plates with the protective film obtained, the peel strength was measured by peeling the protective film in the 180° direction at a tensile speed of 300 mm/min in the longitudinal direction according to JIS Z0237 ( N/25 mm). The results are shown in Table 1. Further, the light guide plates of the two types of protective films obtained above were placed in an oven at 70 ° C for 40 minutes (heat resistance test), taken out, and cooled to room temperature, and the peel strength was measured in the same manner. The results are shown in Table 1.

(Adhesive property evaluation)

In the same manner, a protective film is bonded to the light guide plate, and the protective film and the light guide plate are cut into an A4 size to prepare a light guide plate with a protective film, in place of the light guide plate of 50 to 60 ° C in advance. With respect to the obtained light guide plate with a protective film, it was evaluated whether the protective film peeled off from the end portion by 5 mm or more. The peeling of the protective film from the end portion to 5 mm or more was recorded as peeling. The case where the peeling of the protective film from the end portion was less than 5 mm was recorded as no peeling. The results are shown in Table 1.

(evaluation of peeling characteristics)

The ease of peeling (workability) of the protective film was evaluated for the light guide plate with the protective film of A4 size cut as described above. The ease of peeling in the case where the protective film is peeled off at one time without applying excessive force is indicated by ○. The ease of peeling in the case where the protective film cannot be peeled off at one time is indicated by ×. The ease of peeling between ○ and × is represented by Δ. The results are shown in Table 1. Further, the light guide plate having the protective film cut into an A4 size was placed in an oven at 70 ° C for 40 minutes, taken out, and cooled to room temperature, and the easiness of peeling was evaluated in the same manner. The results are shown in Table 1.

(Example 2)

A light guide plate with a protective film was produced and evaluated in the same manner as in Example 1 except that a polypropylene film (trade name: FM-470, manufactured by Daewoo Paper Co., Ltd.) was used as the protective film. The results are shown in Table 1.

(Example 3)

A light guide plate with a protective film was produced and evaluated in the same manner as in Example 1 except that a polypropylene film (trade name: FM-382, manufactured by Daewoo Paper Co., Ltd.) was used as the protective film. The results are shown in Table 1.

(Comparative Example 1)

A light guide plate with a protective film was produced in the same manner as in Example 1 except that a polyethylene film (trade name: ML2020, manufactured by Hitachi Chemical Co., Ltd.) was used as a protective film, and the peel strength was measured, and the adhesion characteristics were evaluated. The results are shown in Table 1.

(Comparative Example 2)

A light guide plate with a protective film was produced and evaluated in the same manner as in Example 1 except that a polypropylene film (trade name: XML-K171, manufactured by Hitachi Chemical Co., Ltd.) was used as the protective film. The results are shown in Table 1.

(Reference example 1)

A light guide plate with a protective film was produced in the same manner as in Comparative Example 1, except that a light guide plate (planar light guide plate) having a flat surface was used instead of the shape light guide plate having the surface on which the convex portion was formed, and the peel strength was measured. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3, a light guide plate with a protective film excellent in both adhesive properties and peeling properties was obtained. On the other hand, in Comparative Examples 1 and 2, good results were obtained in at least one of adhesive properties and peeling properties. Therefore, it can be seen that in the shape light guide plate, by setting the peeling strength between the surface on which the convex portion of the light guide plate is formed and the protective film to a specific range, it is possible to obtain both the adhesion property and the peeling property. The light guide plate of the film.

30‧‧‧Light guide

31‧‧‧ surface

35‧‧‧ convex

40‧‧‧Protective film

42‧‧‧Protective film

51‧‧‧Mold

52A‧‧‧1st squeeze roller

52B‧‧‧2nd squeezing roller (shape roller)

52D‧‧‧Preloading roller

53‧‧‧Transfer mode

57‧‧‧Resin input

58‧‧‧Extrusion machine

60‧‧‧Continuous resin sheet

90‧‧‧Light guide plate with protective film

Fig. 1 is a schematic block diagram showing a manufacturing apparatus of a light guide plate with a protective film according to an embodiment.

Fig. 2 is a perspective view schematically showing the configuration of a light guide plate.

Fig. 3 is a cross-sectional view schematically showing a concave portion formed in a transfer mold and a convex portion formed on the light guide plate.

Fig. 4 is a cross-sectional view showing a light guide plate with a protective film according to an embodiment.

Fig. 5 is a flow chart showing the procedure of a method of manufacturing a light guide plate with a protective film according to an embodiment.

30‧‧‧Light guide

31‧‧‧ surface

32‧‧‧Back

35‧‧‧ convex

40‧‧‧Protective film

42‧‧‧Protective film

90‧‧‧Light guide plate with protective film

Claims (3)

A light guide plate with a protective film, comprising: a light guide plate having a surface on which a convex portion is formed; and a protective film attached to the surface on which the convex portion is formed; and bonding the protective film to the heating to a peeling strength between the light guide plate and the protective film after the light guide plate at 40 ° C is 0.1 to 0.8 N / 25 mm, and the protective film is bonded to the light guide plate after heating the light guide plate to 70 ° C The peeling strength between the above protective films is 0.1 to 0.8 N/25 mm. The light guide plate with a protective film according to claim 1, wherein after the protective film is attached to the light guide plate heated to 40 ° C, the light guide plate and the protective film are heat-treated at 70 ° C for 40 minutes. The peeling strength is 0.1 to 0.8 N/25 mm, and after the protective film is bonded to the light guide plate heated to 70 ° C, the light guide plate and the protective film are heat-treated at 70 ° C for 40 minutes. The peel strength is 0.1 to 0.8 N/25 mm. A protective film for use as a light guide plate with a protective film as claimed in claim 1 or 2.