TWI590941B - Light guide plate manufacturing method - Google Patents

Description

Light guide plate manufacturing method

The present invention relates to a method of manufacturing a lens sheet having a plurality of ridge lenses arranged in parallel on a surface of a resin sheet. In particular, the present invention relates in particular to a thickness which is suitable for manufacturing a resin sheet and has a high thickness of a ridge lens. A method of wide-ranging lens sheets.

It is known that a lens sheet of a plurality of ridge lenses arranged in parallel is provided on the surface of the resin sheet. The shape of the ridge lens is, for example, a lens having a semi-conical shape or a triangular prism-shaped 稜鏡 lens having a vertex angle of 90 degrees (see Patent Documents 1 to 4). In the case of such a lens sheet, it is generally required to increase the aspect ratio of the ridge lens (i.e. (height of the ridge lens) / (the pitch of the ridge lens)).

The method for producing the lens sheet described above may be a method of extrusion molding or injection molding of a thermoplastic resin, or a method of photocuring an ultraviolet curable resin. Among them, a method of extrusion molding a thermoplastic resin is preferred from the viewpoint of continuous productivity.

As a method of producing a lens sheet having a ridge lens on both sides by extrusion molding using a thermoplastic resin, a method of performing multilayer extrusion molding by sandwiching a thermoplastic resin having a high viscosity with a thermoplastic resin having a low viscosity is known. When the lens sheet is produced by such a method, it is considered that the resin dripping of the molten sheet when the lens sheet having the lenticular lens having a high aspect ratio is produced can be suppressed, and the production stability is improved (see Patent Document 5).

Further, it is known to use a pattern roll in which a thermal buffer member is disposed between a core body and a pattern member as a shaping metal mold, and to transfer a shape of the pattern member onto an extruded sheet in a molten state, revealing a high width A manufacturing example of a lens sheet in which a 稜鏡 lens of 0.5 is arranged on a resin sheet having a thickness of 1 mm (see Patent Document 6).

One of the above-mentioned lens sheets is used for liquid A light guide plate of a crystal display device or the like. In recent years, in recent years, the development of large-scale devices has progressed, and in order to ensure the strength of the light guide plate, a resin sheet is required to be thickened.

According to the study of the inventors, etc., in Patent Document 5 In the method described, when the resin sheet is thickened, the shaping rate (that is, the height of the lenticular lens of the lens sheet/the depth of the groove of the shaping metal mold) is lowered, and the aspect ratio of the ridge lens is lowered, and it is found that There is room for improvement.

Further, in the method described in Patent Document 6, since heat is efficiently transmitted to the resin sheet by the heat buffer member, when the thickness of the resin sheet is thick, cooling and hardening of the formed uneven pattern are not progressed rapidly, from the pattern roll. After peeling off, the lenticular lens tends to be deformed, which becomes a problem.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Publication No. 2-190835

Patent Document 2, JP-A-2009-37803

Patent Document 3, JP-A-2009-265380

Patent Document 4, JP-A-2009-283383

Patent Document 5 Japanese Patent Publication No. 4-299329

Patent Document 6 JP-A-2003-53834

The object of the present invention is to provide a method for producing a lens sheet by extrusion molding using a thermoplastic resin, and to provide a resin sheet which is easy to manufacture and suitable for a large light guide plate and the like, and has a thick thickness and a high aspect ratio of the ridge lens. A method of extruding a lens sheet having a uniform width direction.

With the present invention, the above object can be solved by an invention comprising the following forms:

[1] A method for producing an extrusion of a lens sheet, comprising a first step of lowering a thermoplastic resin (A) and an MFR (a value measured according to ISO 1133 at 230 ° C under a load of 37.3 N) to be less than the thermoplastic resin (A) The thermoplastic resin (B) is extrusion-molded, and a multilayer sheet in a molten state is obtained by a multi-manifold mold, and the molten multi-layer sheet is provided adjacent to the first layer, which is composed of a thermoplastic resin (A) per unit length. The volume is y (y is a positive number) and is a surface layer; and the second layer is composed of a thermoplastic resin (B); and the second step is to have a plurality of volumes x per unit length (x is a positive number) The shaping die of the groove satisfying the following formula (1) is adhered to the surface composed of the first layer of the multilayer sheet in the molten state obtained in the first step to form n (n is a natural number) ridge lens.

0.7≦y/nx≦2.0 (1)

[2] The method for producing a lens sheet according to [1], wherein the y, n, and x satisfy the following formula (2): 1.05 ≦ y / n x ≦ 1.4 (2)

According to the present invention, it is industrially easy to manufacture a lens sheet having a thick thickness of a resin sheet suitable for a large light guide plate or the like and a high aspect ratio of the ridge lens. For example, the thickness of the resin sheet is 2.5 to 15 mm, and the width and width of the ridge lens are high. A lens sheet with a ratio of 0.3 to 1.0.

1‧‧‧Extrusion molding machine

2‧‧‧Multilayer extrusion T-die

31‧‧‧Pushing the metal mold roller

32‧‧‧Shaping metal mold roller

33, 34‧‧‧ Cooling roller

4‧‧‧Lens Sheet

Fig. 1 is a graph showing the relationship between the forming ratio of the central portion of the ridge lens of Examples 1 to 5 and Comparative Examples 3 and 4 and y/nx.

Fig. 2 is a schematic view showing an extrusion molding machine for manufacturing lens sheets of the examples and the comparative examples.

[thermoplastic resin]

The MFR of the thermoplastic resin (B) used in the production method of the present invention is smaller than the MFR of the thermoplastic resin (A). That is, when the MFR of the thermoplastic resin (A) is MFR (A) and the MFR of the thermoplastic resin (B) is MFR (B), the value of MFR (A) / MFR (B) exceeds 1. The value of MFR(A)/MFR(B) is preferably in the range of 1.5 to 40, more preferably in the range of 2 to 30, and most preferably in the range of 3 to 20. A value of MFR(A)/MFR(B) of more than 1 can increase the aspect ratio of the lenticular lens. From the viewpoint of improving the uniformity of the thickness of the obtained lens sheet, the value of MFR (A) / MFR (B) is preferably 40 or less. In the present specification, the MFR is a value measured under conditions of 230 ° C and a load of 37.3 N in accordance with ISO 1133.

MFR (A) is superior to the conventional extrusion from the viewpoint that the thermoplastic resin (A) is filled in the groove of the shaping metal mold as much as possible without gaps. The range of the thermoplastic resin used in the forming is good. For example, the range of 7 to 50 g/10 minutes is better, the range of 7 to 30 g/10 minutes is better, the range of 10 to 25 g/10 minutes is even better, and the range of 10 to 20 g/10 minutes is particularly good. When the MFR (A) is less than 7 g/10 minutes, the forming ratio of the obtained lens sheet may be lowered, and if it is more than 50 g/10 minutes, the amount of extrusion of the thermoplastic resin (A) during extrusion molding may be obtained. It will be unstable.

In addition, in this specification, the description of the two numerical values connected by "~" means the two numerical values and the range between them.

MFR (B) from the viewpoint of operational stability of extrusion molding, The range of 0.2~5g/10 points is better, the range of 0.4~4g/10 points is better, and the range of 0.5~3g/10 points is better. When the MFR (B) is less than 0.2 g/10 minutes, the pressure of the molten resin in the extrusion molding machine becomes too high, and the extrusion molding machine may be broken. When it is more than 5 g/10 minutes, the obtained may be obtained. The uneven thickness of the lens sheet increases.

[first step]

In the first step, the thermoplastic resin (A) and thermoplastic The resin (B) is extrusion-molded to obtain a multilayer sheet in a molten state, and the multilayer sheet in a molten state is provided with a first layer which is composed of a thermoplastic resin (A) and is a surface layer, and a second layer which is composed of The thermoplastic resin (B) is composed.

The conditions for extrusion molding of the thermoplastic resin (A) and the thermoplastic resin (B) are not particularly limited. Usually, the thermoplastic resin (A) and the thermoplastic resin (B) are each melted in a cylinder of an extrusion molding machine, laminated in an extrusion die, and then extrusion-molded to obtain a multilayer sheet in a molten state. The extrusion die uses a multi-manifold mold having a plurality of manifolds inside from the viewpoint of making the thickness of each layer uniform.

When the multilayer sheet is produced by the multi-manifold mold used in the present application, the thermoplastic resin constituting each layer is supplied to the respective flow paths inside the mold, and the resins constituting the respective layers are respectively spread in the width direction of the sheet, and then in the mold. The spit exit is merged and squeezed out. Therefore, with the multi-manifold mold, even if the fluidity of the resin is different, the thickness of each layer can be made uniform in the width direction of the sheet.

In terms of extrusion molding, thermoplastic resin (A) and thermoplastic The temperature at which the resin (B) is melted (forming temperature) is preferably, for example, higher than the load deflection temperature of the thermoplastic resin (A) and the thermoplastic resin (B) by 130 to 180 ° C, respectively. The molding temperature of the thermoplastic resin (A) and the thermoplastic resin (B) may also be different. In the formation of the ridge lens of the second step, from the viewpoint of improving the fluidity of the thermoplastic resin (A) to improve the forming ratio, it is preferable to form the high thermoplastic resin (A) at a molding temperature higher than that of the thermoplastic resin (B). The temperature is still high.

Multi-manifold molds are typically used to heat individual thermoplastic trees Fat heater. The heater of the multi-manifold mold may be different from each thermoplastic resin. In this case, the temperature (forming temperature) of the heater of each thermoplastic resin can be changed. The temperature of the heater in contact with the thermoplastic resin (A) of the first layer is higher than the temperature of the heater in contact with the thermoplastic resin (B) of the multi-manifold mold, and is usually preferably increased by a temperature difference of 5 to 40 ° C to 10 The temperature difference of ~35 °C is better, and the temperature difference of 15~30 °C is better. When such a temperature difference is set to 40 ° C or less, the obtained lens sheet is less likely to cause warpage.

The amount of extrusion of the thermoplastic resin (A) is not particularly limited, but may be, for example, 5 to 100 kg/hr.

The amount of extrusion of the thermoplastic resin (B) is not particularly limited, but may be, for example, 50 to 400 kg/hr.

The ratio of the extrusion amount of the thermoplastic resin (A) to the thermoplastic resin (B) can be set to, for example, 1:2 to 1:50.

The extrusion speed of the multilayer sheet in a molten state is not particularly limited, but may be, for example, 0.1 to 10 m/min.

The volume y per unit length of the first layer can be adjusted in accordance with the thickness of the multilayer sheet in a molten state adjusted according to the amount of extrusion of each thermoplastic resin used and the width of the manifold mold discharge port.

In the extrusion molding, an antioxidant, a heat-resistant deterioration agent, an ultraviolet absorber, a photostabilizer, a lubricant, or the like may be added to one or both of the thermoplastic resin (A) and the thermoplastic resin (B) as needed. A release agent, an antistatic agent, a polymer processing aid, a flame retardant, a dye pigment, a light diffusing agent, an impact modifier, a phosphor, and the like.

The thickness of the multilayer sheet in a molten state obtained in this step is usually in the range of 2 to 20 mm, and more preferably in the range of 2.5 to 10 mm. When the thickness is thinner than 2 mm, the strength of the resin sheet may be insufficient. If it is thicker than 20 mm, the cooling and hardening of the formed uneven pattern may not progress rapidly, and the ridge lens may be deformed after being peeled off from the shaping die. .

The ratio of the thickness of the first layer to the second layer of the multilayer sheet in a molten state obtained in this step can be set to, for example, 1:2 to 1:50.

In the present specification, the volume per unit length of the first layer is defined as y. Further, the first layer is a surface layer of a multilayer sheet in a molten state, and is adhered to the shaping metal mold in the second step. This result, the first The layer becomes at least a portion of the n ridge lenses formed in the second step.

The second layer may be a sheet of a multilayer sheet in a molten state Layers can also be covered by other layers. In other words, the multilayer sheet in a molten state may contain other layers than the first layer and the second layer. Such other layer may be composed of a thermoplastic resin (A) or a thermoplastic resin (B), or may be composed of another thermoplastic resin. From the viewpoint of suppressing warpage of the obtained lens sheet, it is preferable to use a third layer made of a thermoplastic resin (A) as another layer, and to form the first layer/second layer/third layer in the order of the first layer/second layer/third layer. Three layers of multilayer sheets. In the case of producing such a three-layer multilayer sheet, in this case, the extrusion amount of the third layer is preferably in the range of 0.9 to 1.1 times the extrusion amount of the first layer, and is preferably equal to the extrusion amount of the first layer.

[Second step]

In the second step, the shaping gold having a plurality of grooves is made The mold is adhered to the surface of the first layer of the multilayer sheet in the molten state obtained in the first step to form n ridge lenses, and the volume x per unit length of the groove satisfies the formula (1). At this time, it is preferable that the pressing metal mold is adhered to the other surface of the multilayer sheet in a molten state.

The shape of the shaping die and the pressing die can be, for example, a belt shape, a drum shape or the like.

The total volume per unit length of the grooves of the forming metal mold required to form the n ridge lenses is nx. The value of y/nx of the formula (1) is in the range of 0.7 to 2.0 from the viewpoint of achieving a high shaping rate, a range of 1.05 to 1.4 is preferable, and a range of 1.2 to 1.3 is more preferable.

The number n of ridge lenses of the lens sheet of the present invention is determined by (the width of the manufactured lens sheet) / (the distance between the lenticular lenses). Depending on the number n of such ridge lenses, the volume y per unit length of the first layer of the multilayer sheet in the molten state determined in the first step, and the per unit length of the groove of the shaping die The volume x adjusts the value of y/nx to the desired range. Specifically, when the multilayer sheet in a molten state is produced in the first step, the total amount of extrusion per unit time of all the thermoplastic resins used is r, and the unit time of the thermoplastic resin (A) The amount of extrusion is r ₁ , and by adjusting the ratio r ₁ /r, the value of y/nx can be adjusted, and y/nx becomes larger as the r ₁ /r is increased.

Determine the first layer in the shaping metal mold according to the value of y/nx Which of the volumes in the tank is satisfied. That is, when the value of y/nx exceeds 1, only the thermoplastic resin (A) fills the groove, and the first layer of the obtained lens sheet can form a part of the ridge lens and the resin sheet, and the second layer can form a resin sheet. . On the other hand, when the value of y/nx is less than 1, the entire amount of the thermoplastic resin (A) in the groove and a part of the thermoplastic resin (B) are filled, and the first layer of the obtained lens sheet can form a ridge lens. As part of the second layer, a part of the ridge lens and the resin sheet can be formed. When the value of y/nx is 1, only the thermoplastic resin (A) is filled in the groove, and the first layer of the obtained lens sheet can only form a ridge lens, and the second layer can only form a resin sheet. As described above, the manufacturing method of the present invention achieves the object by adjusting the ratio of the lenticular lens formed in the first layer and the ratio of the first layer formed in the lenticular lens.

The temperature of the forming metal mold is from the thermoplastic resin (A) Can be filled in a shaped metal mold without gaps, in thermoplastic resin The range of the load deflection temperature of (A) is preferably ±10 °C. When the temperature of the shaping metal mold is lower than the load deflection temperature of the thermoplastic resin (A) by more than 10 ° C, the resin cannot be sufficiently filled in the shaping metal mold, and when the height exceeds 10 ° C, the resin is released from the shaping metal mold. This may not proceed smoothly, resulting in an accident in which the resin sheet is wound on the drum or a surface defect called a mold release mark.

The temperature at which the metal mold is pushed is preferably in the range of (the deflection temperature of the thermoplastic resin (B) is -20 ° C) to (the deflection temperature of the thermoplastic resin (B)) from the viewpoint of sufficiently cooling the thermoplastic resin (B). .

Further, the load deflection temperature of the thermoplastic resin (A) and the thermoplastic resin (B) was measured in accordance with ISO 75-2.

From the viewpoint of increasing the aspect ratio of the ridge lens of the obtained lens sheet, the pitch of the forming metal mold to be used is usually preferably in the range of 0.05 to 1.0 mm, and more preferably in the range of 0.1 to 0.8 mm.

In the present invention, the sheet molded article obtained after the second step is cut in a direction perpendicular to the normal extrusion direction, and the length is adjusted to form a lens sheet. Further, both ends in the extrusion width direction parallel to the extrusion direction may be appropriately cut and the width may be adjusted.

[Examples]

The present invention will be described in detail below by way of examples and comparative examples, but the invention is not limited thereto.

The shaping metal mold used was as follows: the surface shape of the shaping metal mold was transferred using a two-liquid hardening type resin, and the cross-sectional shape thereof was observed with a microscope to measure the distance and depth between the grooves. As a result, the cross-sectional shape of the groove of the shaping metal mold cylinder was a semi-elliptical shape having a pitch of 0.4 mm and a depth of 0.231 mm.

Further, the area of the groove of the semi-elliptical shape was calculated from the obtained groove pitch and depth, and the volume x (m ³ /m) per unit length was calculated. As a result, x is 0.14 × 10 ^-6 m ³ .

The resulting lens sheet was evaluated by the following method:

(1) height of the lenticular lens

The cross section perpendicular to the extrusion direction of the lens sheet was observed with a microscope, and the distance parallel to the thickness direction from the top of the ridge lens to the valley portion was measured. The value measured in the central portion of the extrusion width direction is the value measured at a distance of 600 mm from the central portion in the extrusion width direction to the end portion in the extrusion width direction at a height of the ridge lens at the center portion. The height of the lenticular lens at the end.

(2) Thickness of resin sheet

The cross section perpendicular to the extrusion direction of the lens sheet was observed with a microscope, and the distance from the valley portion of the ridge lens to the surface of the third layer was measured.

(3) Calculate y/nx

The extrusion amount Q (kg/hour) of the thermoplastic resin (A), the extrusion speed v (m/min) of the lens sheet, and the specific gravity ρ (g/cm ³ ) of the thermoplastic resin (A) were calculated according to the following formula. Volume y (m ³ /m) per unit length of 1 layer: y = Q / (60000 × ρ × v) (m ³ / m)

From the calculated y and the number of ridge lenses n formed and the above calculated x (m ³ /m), y/nx was calculated.

(4) The spacing of the lenticular lenses

The cross section perpendicular to the extrusion direction of the lens sheet was observed with a microscope, and the distance from the top of the ridge lens to the top of the adjacent ridge lens was measured.

(5) The aspect ratio of the lenticular lens

The height of the ridge lens at the center portion measured in the above (1) is divided by the pitch of the ridge lens measured in the above (4) as the aspect ratio.

(6) Forming rate (%)

The percentage of the height of the ridge lens at the center portion and the end portion measured in the above (1) to the depth of the groove of the shaping die was determined as the shaping rate (%) of the center portion and the end portion.

(7) Thickness of the third layer

The cross section perpendicular to the extrusion direction of the sheet was observed with a microscope. The value measured in the central portion in the extrusion width direction is the thickness of the third layer in the center portion, and is measured at a distance of 600 mm from the center portion in the extrusion width direction to the end portion in the extrusion width direction. The thickness of the third layer of the end.

Figure 2 is an extrusion used in the examples and comparative examples. A schematic view of the molding machine 1. The extrusion molding machine 1 is composed of an extrusion spiral portion (not shown), a multilayer extrusion T-type manifold mold 2, a pressing die cylinder 31, a shaping die cylinder 32, and cooling drums 33 and 34. On the surface of the shaping die drum 32, 3250 grooves extending along the outer circumference of the drum are provided.

The surfaces of the pressing die 31 and the cooling rollers 33, 34 are smoothed. The molten strip-shaped resin is discharged downward from the molten resin discharge portion of the multilayer extruded T-type manifold mold 2. The pressing die roll 31 and the shaping die roll 32 are opposed to each other so as to sandwich the molten resin, and are arranged parallel to each other and horizontally. The cooling drums 33 and 34 are arranged in parallel with the pressing die drum 31 and the shaping die drum 32 so that the respective rotation axes are located on the same plane.

In the examples and comparative examples, the following acrylic resin (a) and acrylic resin (b) were used: acrylic resin (a): "PARAPET GH" manufactured by Kuraray Co., Ltd., MFR = 10 (according to ISO 1133, at 230 ° C, load) 37.3N measurement catalog value), load deflection temperature = 95 ° C (according to ISO 75-2, annealing, catalogue value measured by load 1.82 MPa), specific gravity 1.19.

Acrylic resin (b): "PARAPET EH" manufactured by Kuraray Co., Ltd., MFR = 1.3 g/10 min (catalog value measured according to ISO 1133 at 230 ° C, load 37.3 N), load deflection temperature = 93 ° C (measurement conditions) : According to ISO75-2, there is annealing, the catalog value measured by the load of 1.82MPa), and the specific gravity is 1.19.

Example 1

The acrylic resin (a) and the acrylic resin (b) are placed in an extrusion molding machine, the acrylic resin (a) is heated to 260 ° C, and the acrylic resin (b) is heated to 245 ° C in the extrusion width direction of the discharged molten resin. The multilayer extruded T-multi-manifold mold having a length of about 1500 mm is laminated in the order of acrylic resin (a), acrylic resin (b), and acrylic resin (a), and the acrylic resin (a) is extruded as the first layer. A multilayer sheet in which the acrylic resin (b) is the second layer and the acrylic resin (a) is the third layer in a molten state. The extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 20 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 200 kg/hr.

Next, the multi-layered sheet in the molten state is supplied between the pressing metal mold cylinder 31 and the shaping metal mold cylinder 32 which are disposed apart from each other and disposed in parallel with each other to give a lens shape, and secondly, it is brought into close contact with the cooling drums 33, 34. A sheet molded article in which a plurality of ridge lenses are arranged on the surface is obtained. The sheet molded article has a width of about 1.4 (m).

The surface temperature of the pressing die 31 was 80 ° C, the surface temperature of the shaping die 32 was 100 ° C, the surface temperature of the cooling drum 33 was 100 ° C, and the surface temperature of the cooling drum 34 was 70 ° C. The exit speed is 0.8 m/min.

The value of y/nx is 0.750.

The obtained sheet molded product was cut into a length of 1.3 m perpendicular to the extrusion direction. Further, both ends of the extrusion width direction parallel to the extrusion direction were cut at equal widths to have a width of 1.3 m, and a lens sheet was produced.

The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.8 mm, the height of the ridge lens at the center portion is 0.16 mm, and the height of the ridge lens at the end portion is 0.159 mm, ridge shape. The aspect ratio of the lens was 0.400, and the shaping rate at the center portion and the end portion was 69%. The third layer of the central portion has a thickness of 0.136 mm, and the third layer of the end portion has a thickness of 0.135 mm.

Example 2

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 28.8 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 182.3 kg/hr, the rest was A lens sheet was produced in the same manner as in Example 1. As a result, y/nx becomes 1.081. The pitch of the lenticular lens of the lens sheet obtained above was 0.4 mm, the thickness of the resin sheet was 2.8 mm, the height of the ridge lens at the center portion was 0.164 mm, and the height of the ridge lens at the end portion was 0.162 mm, ridge shape. The aspect ratio of the lens was 0.410, the shaping rate at the center portion was 71%, and the shape at the end portion was 70%. The third layer of the central portion has a thickness of 0.196 mm, and the third layer of the end portion has a thickness of 0.196 mm.

Example 3

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 32 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 176 kg/hr, A lens sheet was produced in the same manner as in Example 1. As a result, y/nx becomes 1.230. The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.8 mm, the height of the ridge lens at the center portion and the end portion is 0.177 mm, and the aspect ratio of the ridge lens is 0.443, and the center The shaping rate of the part and the end is 77%. The third layer of the central portion has a thickness of 0.223 mm, and the third layer of the end portion has a thickness of 0.222 mm.

Example 4

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 36.8 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 164.4 kg/hr, the rest was A lens sheet was produced in the same manner as in Example 1. As a result, y/nx becomes 1.379. The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.8 mm, the height of the ridge lens at the center portion is 0.164 mm, and the height of the ridge lens at the end portion is 0.166 mm, ridge shape. The aspect ratio of the lens was 0.410, the shaping rate at the center portion was 71%, and the shaping rate at the end portion was 72%. The third layer of the central portion and the end portion has a thickness of 0.25 mm.

Example 5

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 51.5 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 137 kg/hr, the rest was A lens sheet was produced in the same manner as in Example 1. As a result, y/nx becomes 1.930. As above The lenticular lens has a pitch of 0.4 mm, the thickness of the resin sheet is 2.8 mm, the height of the ridge lens at the center is 0.156 mm, the height of the ridge lens at the end is 0.157 mm, and the height of the ridge lens is high. The width ratio is 0.390, and the shaping rate at the center portion and the end portion is 68%. The third layer of the central portion has a thickness of 0.35 mm, and the third layer of the end portion has a thickness of 0.348 mm.

Comparative example 1

The acrylic resin (b) was placed in an extruder, heated to 245 ° C, and the sheet in a molten state was extruded from the T-manifold die at an extrusion amount of 240 kg / hour. Then, the sheet in the molten state is supplied between the pressing die cylinder 31 and the shaping die cylinder 32 which are disposed apart from each other and disposed in parallel with each other, and is given a lens shape, and then brought into close contact with the cooling rollers 33 and 34. A lens sheet in which a plurality of ridge lenses are arranged on the surface is produced. The surface temperature of the pressing die 31 was 80 ° C, the surface temperature of the shaping die 32 was 100 ° C, the surface temperature of the cooling drum 33 was 100 ° C, and the surface temperature of the cooling drum 34 was 70 ° C. The exit speed is 0.8 m/min.

The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.9 mm, the height of the ridge lens at the center portion and the end portion is 0.100 mm, and the aspect ratio of the ridge lens is 0.250. The shaping rate of the part and the end was 43%.

Comparative example 2

The same manner as in Comparative Example 1 except that the extrusion amount of the acrylic resin (b) was 160 kg/hr, and the pressing die 31 and the shaping die 32 were separated by 2 mm and arranged in parallel with each other. A lens sheet 4 is manufactured.

The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 1.9 mm, the height of the ridge lens at the center portion and the end portion is 0.150 mm, and the aspect ratio of the ridge lens is 0.375. The shaping rate of the part and the end is 65%.

Comparative example 3

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 5.9 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 228.2 kg/hr, the rest was A lens sheet was produced in the same manner as in Example 1. As a result, y/nx becomes 0.221. The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.9 mm, the height of the ridge lens at the center portion is 0.115 mm, and the height of the ridge lens at the end portion is 0.113 mm, ridged. The aspect ratio of the lens was 0.288, the shaping rate at the center portion was 50%, and the shape at the end portion was 49%. The third layer of the central portion and the end portion has a thickness of 0.040 mm.

Comparative example 4

Except that the extrusion amount of the acrylic resin (a) (the first layer and the third layer) was 88.2 kg/hr, and the extrusion amount of the acrylic resin (b) (the second layer) was 63.5 kg/hr, and In the first embodiment, a lens sheet was produced in the same manner. As a result, y/nx becomes 3.309. The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.9 mm, the height of the ridge lens at the center portion and the end portion is 0.112 mm, and the aspect ratio of the ridge lens is 0.280, the center. The shaping rate of the part and the end is 48%. The third layer of the central portion has a thickness of 0.600 mm, and the third layer of the end portion has a thickness of 0.597 mm.

Comparative Example 5

A lens sheet was produced in the same manner as in Comparative Example 1, except that the acrylic resin (a) was used instead of the acrylic resin (b) and heated to 260 ° C for extrusion. The molten sheet extruded from the T-type manifold mold is frequently broken, and stable production cannot be performed. Further, the shape of the lenticular lens of the obtained lens sheet is not uniform and is not worth practical.

Comparative Example 6

A lens sheet was produced in the same manner as in Example 3 except that the multilayer extruded T-type manifold mold was changed to a multilayer extruded T-type square mold. As a result, y/nx becomes 1.230. The lenticular lens of the lens sheet obtained above has a pitch of 0.4 mm, the thickness of the resin sheet is 2.8 mm, the height of the ridge lens at the center portion is 0.165 mm, and the height of the ridge lens at the end portion is 0.114 mm, ridge shape. The aspect ratio of the lens was 0.413, the shaping rate at the center portion was 71%, and the shape at the end portion was 49%. The third layer of the central portion has a thickness of 0.230 mm, and the third layer of the end portion has a thickness of 0.088 mm.

Table 1 shows the values of y/nx of the lens sheets obtained in the examples and the comparative examples, the heights of the lenticular lenses, the aspect ratio, the shaping ratio, and the like.

In the first embodiment, the first to fifth embodiments and the third comparative example are shown. The relationship between the shaping rate of the central portion of the lenticular lens of the lens sheet obtained in 4 and y/nx.

E1 to E5 in Fig. 1 are sequentially shown in the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment, and the C3 and C4 systems are respectively displayed in the comparative example 3 and the comparative example 4.

As is apparent from Fig. 1 and Table 1, the lens sheets obtained in Examples 1 to 5 were higher in the forming ratio and the height and width of the lenticular lens than the lens sheets obtained in Comparative Examples 3 and 4.

Further, from Comparative Examples 1 and 2, the shape ratio of the lens sheet made of the acrylic resin (b) and the height and width of the ridge lens are relatively low, and in particular, when the thickness of the resin sheet is thick, the tendency is large. .

Further, from Comparative Example 5, it was found that the lens sheet produced only of the acrylic resin (a) could not be stably produced, and the shape of the lens was not uniform.

Further, as is understood from Comparative Example 6, the thickness of the layer composed of the acrylic resin (a) of the lens sheet which does not use the multi-manifold mold differs in the extrusion width direction, and the forming ratio is not uniform.

From the above results, according to the method for producing a lens sheet of the present invention, even when the thickness of the resin sheet is 3.0 mm, a high forming ratio can be achieved, and an aspect ratio of the ridge lens can be obtained. Lens sheet.

Claims (2)

An extrusion manufacturing method of a light guide plate composed of a lens sheet, comprising: a first step of lowering thermoplastic resin (A) and MFR (value measured according to ISO 1133 at 230 ° C under a load of 37.3 N) The thermoplastic resin (B) and the thermoplastic resin (A) of the resin (A) are extrusion-molded, and a multilayer sheet having a thickness of 2 to 20 mm in a molten state is obtained by a multi-manifold mold, and the multilayer sheet in a molten state is sequentially provided: first a layer composed of a thermoplastic resin (A) having a volume per unit length of y (y is a positive number) and being a surface layer; a second layer comprising a thermoplastic resin (B); and a third layer And comprising a thermoplastic resin (A); and a second step of forming a shape of the groove having a volume x (x is a positive number) per unit length satisfying the following formula (1) and a pitch of 0.05 to 1.0 mm The surface composed of the first layer of the multilayer sheet in the molten state obtained in the first step is adhered to form n (n is a natural number) lenticular lens parallel to the extrusion direction, 0.7 ≦ y / n x ≦ 2.0 (1 ). An extrusion manufacturing method of a light guide plate comprising a lens sheet according to the first aspect of the invention, wherein the y, n, and x satisfy the following formula (2): 1.05 ≦ y / n x ≦ 1.4 (2).