JP2002067057A - Manufacturing method of lens sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a long lens sheet by suppressing the occurrence of uneven thickness, uniformly curing an active energy ray-curable composition over a wide range and improving optical accuracy. . SOLUTION: An active energy ray-curable composition 10 in a tank 12 is supplied from a nozzle 13 between a cylindrical lens mold 7 and a transparent substrate 9, and an active energy ray is supplied from an irradiation device 14 through the transparent substrate 9. Irradiation is performed to transfer and form a lens portion made of an active energy ray-curable resin, and the lens portion and the transparent substrate 9 are integrally released from the lens mold 7 to obtain a lens sheet 19. Warm water is allowed to flow through the lens mold 7 so that the outer peripheral surface temperature of the lens mold 7 is a predetermined temperature ± 3 ° C.
The lens mold 7 and the transparent substrate 9
Active energy ray-curable composition 10 supplied between
Temperature controller 3 so that the temperature is within a predetermined temperature range of ± 5 ° C.
Control at 0 or other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens sheet such as a prism sheet used for a backlight or the like used as a surface light source element for illumination in a liquid crystal display device or the like, and a display screen such as a projection television or a microfilm reader. The present invention relates to a method for producing a lens sheet such as a lenticular lens sheet or a Fresnel lens sheet used for a projection screen used as a projection screen, and more particularly to a method for continuously producing a long lens sheet.

[0002]

2. Description of the Related Art In recent years,
A portable notebook computer with a color liquid crystal display,
In a portable liquid crystal television, a video integrated liquid crystal television, and the like, the large power consumption of the liquid crystal display device is an obstacle to extending the driving time by the battery. Above all, the ratio of the power consumption of the backlight used in the liquid crystal display device to the power consumption of the entire device is large, and keeping the power consumption of the backlight as low as possible extends the driving time of the device by the battery. This is an important issue in increasing the practical value of products. However, if the brightness of the backlight is reduced by suppressing the power consumption of the backlight, the liquid crystal display becomes difficult to see, which is not preferable. Therefore, 3-691
Japanese Patent Publication No. 84-84, etc. discloses a lens sheet in which a large number of lens units such as prism arrays are formed on the surface in order to reduce the power consumption without sacrificing the brightness of the backlight by improving the optical efficiency of the backlight. Is mounted on the light exit surface side of a light guide.

As such a lens sheet, as proposed in JP-A-5-196808 and JP-A-6-59129, from the viewpoint of accurate transfer of a lens pattern and productivity, etc. What formed the lens part using the active energy ray curable composition, such as an ultraviolet curable composition, is used. For example, a lens portion made of a cured product of an active energy ray-curable composition is integrally formed on a transparent substrate such as a transparent resin film or a transparent resin sheet.

On the other hand, in a projection screen such as a projection television or a microfilm reader, a lenticular lens sheet having lenticular lenses formed on both sides is used in order to obtain a good image.
Conventionally, as a method for manufacturing such a lenticular lens sheet, a method of injection molding or a method of press molding a transparent resin material such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, and a styrene resin is known.

However, in the injection molding method, it is difficult to form a large-sized lenticular lens sheet, and only a relatively small-sized lenticular lens sheet can be formed. In addition, in the press molding method, since the heating and cooling cycle of the resin plate and the lens mold requires a long time, a large number of lens molds are required for mass production of the lenticular lens sheet, and a large lenticular lens sheet is manufactured. For this, the production equipment is very expensive.

On the other hand, there has been proposed a method of injecting an active energy ray-curable composition into a plate-shaped lens mold and then irradiating the composition with an active energy ray to cure and shape the composition. However, although the method using the active energy ray-curable composition can shorten the molding time and improve the productivity, it has problems such as entrapment of bubbles when the composition is injected into the lens mold. In order to solve this, it is necessary to separately perform defoaming treatment of the composition or adopt a method such as slowly injecting the composition, which is still insufficient for mass production. It was not something. In particular,
Depending on the shape of the lens-type transfer pattern, the bubbles are trapped in the grooves, so that the bubbles are likely to be generated, and the bubbles once generated cannot be easily removed, causing a lens defect due to the bubbles. Was.

As a method for preventing the generation of such bubbles, as described in JP-A-1-192529, after supplying an ultraviolet-curable composition to a lens mold so as to form a composition pool. A method of placing a base film on a composition reservoir, laminating the base film while leveling the composition on a lens mold with a pressure roll through the base film, and irradiating ultraviolet rays to cure, shape, and remove the mold. Has been proposed.

Further, the demand for higher definition of an image is increasing, and in order to respond to this demand, the lenticular lens is required to have a fine pitch.
No. 9627, Japanese Patent Application Laid-Open No. 3-64701, etc.
There has been proposed a method of continuously forming lenticular lenses on both surfaces of a light-transmitting substrate using an ultraviolet-curable composition and a cylindrical lens mold.

When a lens sheet having a fine lens portion is continuously formed into an elongated shape using an ultraviolet curable composition, the outer peripheral surface of the cylindrical lens mold is rotated while rotating the cylindrical lens mold. Run the translucent substrate in the direction of its rotation along the same speed at the same speed, supply the ultraviolet curable composition between the translucent substrate and the cylindrical lens mold, The composition is polymerized and cured by irradiating ultraviolet rays through a light-transmissive substrate to form a lens portion made of an ultraviolet-curable resin, and then released from the lens mold.

By the way, in recent years, as the display screen is required to be further enlarged, the lens sheet used in the above-mentioned applications is gradually increased in size (for example, 215 mm in length).
287 mm in width) is required, and it is desired to manufacture a wide and long lens sheet that can be cut out in such dimensions. In addition, there is a demand for further improvement in the quality of displayed images. Therefore, it is required to continuously manufacture wide and long lens sheets having high dimensional accuracy and high optical accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it has been proposed that at least a light-transmitting substrate be formed by using an active energy ray-curable composition such as an ultraviolet-curable composition and a cylindrical lens mold. When manufacturing a long lens sheet having a lens portion made of an active energy ray-curable resin on one surface, it suppresses the occurrence of thickness unevenness depending on the location, improves dimensional accuracy, and furthermore, a wide range of active energy ray-curable compositions. The purpose of the present invention is to improve the optical accuracy by uniformly curing over the entire surface.

[0012]

According to the present invention, there is provided a cylindrical lens type having an outer peripheral surface on which a lens portion transfer pattern is formed, the outer peripheral surface being provided with a light-transmitting substrate. An active energy ray-curable composition is supplied between the material and one surface of the material, and the composition is cured and irradiated by irradiating an active energy ray through the light-transmitting substrate to form the lens portion transfer pattern. Forming a lens portion made of an active energy ray-curable resin having a corresponding shape, and continuously releasing at least the light-transmitting substrate by releasing the lens portion and the light-transmitting substrate from the lens mold integrally; A method of manufacturing a lens sheet provided with a lens portion including a repetitive arrangement of lens units on one surface of the cylindrical lens type, wherein the temperature of the outer peripheral surface of the cylindrical lens mold is set to a predetermined temperature of −3 ° C. to a predetermined temperature. The temperature is controlled so as to be within a range of + 3 ° C., and the temperature of the active energy ray-curable composition supplied between the cylindrical lens mold and the translucent substrate is set to the predetermined temperature −5 ° C. to A method for manufacturing a lens sheet is provided, wherein the temperature is controlled to be within the range of the predetermined temperature + 5 ° C.

In one embodiment of the present invention, the temperature of the outer peripheral surface of the cylindrical lens mold is controlled by flowing a heat medium through the cylindrical lens mold. In one aspect of the present invention, the temperature of the active energy ray-curable composition is controlled by controlling the tank of the active energy ray-curable composition, the supply nozzle, and the supply nozzle and the tank of the active energy ray-curable composition. This is performed by adjusting the temperature of the supply path of the active energy ray-curable composition that connects the above.

In one embodiment of the present invention, the translucent substrate has a lens portion made of an active energy ray-curable resin on the other surface.

In one embodiment of the present invention, the active energy ray-curable composition is sandwiched between the light-transmitting substrate and the lens mold, and the active energy ray-curable composition is irradiated with the active energy ray-curable composition. Irradiate. In one embodiment of the present invention, the lens portion and the light-transmitting substrate by adjusting the nip pressure of a nip roll arranged to face the other surface of the light-transmitting substrate by a pressure adjusting mechanism. Between them, a relaxation layer made of an active energy ray-curable resin is formed. In one embodiment of the present invention, the viscosity at 40 ° C. of the active energy ray-curable composition is 20 to 3000 mPa · S.

In one embodiment of the present invention, the lens-type lens portion transfer pattern is for forming, by transfer, a lens portion including a large number of lens units each having a prism array having a substantially triangular cross section. . In one embodiment of the present invention, the lens-type lens portion transfer pattern,
This is for forming a lens portion including a large number of lenticular lens units by transfer.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a lens sheet 19 manufactured by the method of the present invention. The lens sheet 19 is used to improve the front luminance of a surface light source element such as a backlight of a portable notebook personal computer having a color liquid crystal display device, a liquid crystal display device such as a portable liquid crystal television or a video integrated liquid crystal television. This prism sheet corresponds to the lens sheet according to the present invention. As shown in FIG. 1, in the lens sheet 19, the lens unit 3 including a large number of lens units (prism rows) is formed on one surface of the translucent substrate 2 by an active energy ray-curable resin. The relaxation layer 1 is interposed between the light-transmitting substrate 2 and the lens portion 3.

The relaxation layer 1 is integrally formed of the same active energy ray curable resin as the lens portion 3. This relaxation layer 1
Is formed to a thickness of 1 to 30% of the lens height (H) of the lens portion 3, whereby the occurrence of a spot-like pattern due to polymerization shrinkage during curing of the active energy ray-curable composition can be suppressed. it can.

In the present invention, the surface shape of the lens portion 3 of the lens sheet 19 may be changed depending on the purpose, in addition to the prism surface in which a large number of prism rows are formed parallel to each other as shown in FIG. The shape may be a lenticular lens surface or a wavy lens surface in which a large number of lenticular lenses having a semicircular or semielliptical shape are formed in parallel with each other.

Further, a lens portion comprising a large number of lens units can be formed on the other surface of the lens sheet of FIG. 1 to form a double-sided lens sheet. In FIG. 2 showing an example of such a double-sided lens sheet 29, a lens portion 4 including a large number of lens units (prism rows) is also formed on the other surface of the translucent substrate 2 by an active energy ray-curable resin.
The relaxation layer 1 ′ is interposed between the light-transmitting substrate 2 and the lens unit 4. The lens portions 3 and 4 are made of a transparent base material 2
The same type and size of lens shape may be formed on both surfaces, or different types and sizes of lens shapes may be formed. In the lens sheet of the present invention, the thickness of the lens portions 3 and 4 is preferably about 10 to 150 μm, and the pitch of the lens unit is preferably about 10 to 150 μm. In particular, in the present invention in which a lens portion is formed of an active energy ray-curable resin, the present invention is suitable for a fine-pitch lens sheet used for a surface light source element capable of responding to high definition such as a liquid crystal display device. Is preferably in the range of 10 to 100 μm, and more preferably in the range of 10 to 50 μm.

Further, when the lens unit is a prism array, the apex angle of the prism array is preferably in the range of 50 to 160 °. In general, a light source, a light guide having one side facing the light source as a light incident surface, and a light exit surface having one surface substantially perpendicular to the light incident surface, and disposed on a light exit surface of the light guide. In a surface light source element (edge light type) for a liquid crystal display device which is basically composed of a prism sheet, the prism sheet 19 is arranged such that the prism surface is on the liquid crystal panel side.
Are arranged, the apex angle of the prism array is 80 to 100.
範 囲, preferably in the range of 85 to 95 ゜. On the other hand, when the prism sheet 19 is arranged so that the prism surface is on the light guide side, the apex angle of the prism row is in the range of about 50 to 75 °, preferably 55 to 70 °.
範 囲 range. The lens portions 3 and 4 made of the active energy ray-curable resin are used to improve the brightness of the surface light source element.
Those having a relatively high refractive index are preferred, and specifically, the refractive index is preferably 1.50 or more.
In particular, when the prism sheet 19 is arranged such that the prism surface is on the liquid crystal panel side as in the former case, 1.55
It is preferably at least 1.6, and more preferably at least 1.6.

FIGS. 3 and 4 show lenticular lens sheets each having a lenticular lens used for a projection screen such as a projection television or a microfilm reader, in which the shapes of the lenticular lenses formed on the exit surface are different. It is. The present invention is not limited to a double-sided lenticular lens sheet having lenticular lenses formed on both sides as shown in the figure, but may be a sheet having lenticular lenses formed on one side. FIG. 3 shows a light absorbing layer B formed in a valley between adjacent lenticular lens units formed on the light emitting surface side (upper surface side in the drawing). FIG.
Is a device in which a convex portion is formed between adjacent ones of the lens unit formed on the exit surface side, and a light absorbing layer B is formed on the upper surface of the convex portion. Incidentally, the light absorbing layer B
Can be applied after producing a long lens sheet without a light absorbing layer by the method of the present invention.

The lenticular lens sheet of the present invention
As shown in FIGS. 3 and 4, a first lens unit 5 (an emission surface lenticular lens unit) including a large number of first lenticular lens units on one surface of the translucent substrate 2.
Is formed of an active energy ray-curable resin, and a second lens portion 6 (incident surface lenticular lens portion) including a plurality of second lenticular lens lens units is formed of the active energy ray-curable resin on the other surface. The first and second lens portions 5 and 6 have intervening relaxation layers 1 and 1 ′ between the transparent substrate 2 and the first and second lens portions 5 and 6. The relaxation layers 1, 1 'are usually formed integrally with the same active energy ray curable resin as the lens portions 5, 6. By forming the relaxing layers 1 and 1 ′ to a thickness of 1 to 30% of the lens height (H, H ′), glare due to polymerization shrinkage during curing of the active energy ray-curable composition can be prevented. Occurrence can be suppressed.

In the double-sided lenticular lens sheet of the present invention, the thickness of the lens portions 5 and 6 is 50 to 1000 μm.
m, and the pitch of the lens unit is preferably about 50 to 1000 μm. In particular, the present invention in which a lenticular lens is formed of an active energy ray-curable resin is suitable for a fine-pitch double-sided lenticular lens sheet, and the lens unit pitch is 50 to 500 μm.
It is preferably in the range of, more preferably 50 to
The range is 450 μm.

In the lens sheet of the present invention, the relaxing layers 1 and 1 'preferably have a thickness of 1 to 30% of the lens height as described above. In the present invention, the lens height is the height (H, H ′) of the lens portions 3 to 6 as shown in FIGS. 1 to 4, and the relaxation layers 1 and 1 ′ are made of an active energy ray-curable resin. When formed integrally with the lens portion, the thicknesses of the active energy ray-curable resin and the relaxing layers 1 and 1 '
Means the thickness excluding the thickness. The relief layers 1 and 1 ′ form the lens shape (surface shape of the lens portion) by supplementing the lack of resin in the lens mold due to polymerization shrinkage of the active energy ray-curable resin when forming the lens portions 3 to 6. When the thickness of the relaxing layers 1, 1 'is less than 1% of the lens height, the effect of relaxing the deformation of the lens shape due to the polymerization shrinkage in the relaxing layers 1, 1' is reduced. In contrast, if the height exceeds 30% of the lens height, it becomes difficult to control the unevenness of the thickness of the relaxation layers 1 and 1 ', and the optical characteristics tend to be reduced due to unevenness of the thickness (unevenness). It is in.
The thickness of the relaxation layers 1, 1 'is preferably 1 to 1 of the lens height.
The range is 25%, and more preferably the range is 3 to 15%. When a fine lens unit having a pitch or thickness of about several tens of μm, such as a prism sheet for a surface light source element of a liquid crystal display device as shown in FIGS. 1 ′ is preferably thin, for example, preferably in the range of about 1 to 10 μm, and more preferably in the range of 1 to 5 μm. Further, in a double-sided lenticular lens sheet, for example,
The thickness of 1 ′ is preferably in the range of about 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

The light-transmitting substrate 2 constituting the lens sheet is not particularly limited as long as it is a material that transmits active energy rays such as ultraviolet rays and electron beams. Polyester resins, acrylic resins, polycarbonate resins And a sheet or film of a transparent resin such as a vinyl chloride resin or a polymethacrylimide resin. In particular, polymethyl methacrylate having a lower refractive index than the refractive index of the lens units 3 to 6 and having a low surface reflectance, a mixture of polymethyl acrylate and a polyvinylidene fluoride resin, a polycarbonate resin,
Those made of a polyester resin such as polyethylene terephthalate are preferred. The thickness of the light-transmitting substrate 2 varies depending on the use of the lens sheet.
Those having a range of about μm are used. The light-transmissive substrate 2 has a relaxation layer 1 made of an active energy ray-curable resin.
In order to improve the adhesion with 1 ′, it is preferable that the surface is subjected to an adhesion improving treatment such as an anchor coating treatment.

The active energy ray-curable resin forming the relaxation layers 1 and 1 'of the lens sheet and the lens portions 3 to 6 is not particularly limited as long as it is cured with an active energy ray such as an ultraviolet ray or an electron beam. Not something, for example
Examples include polyesters, epoxy resins, (meth) acrylate resins such as polyester (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate. Among them, (meth) acrylate resins are particularly preferable from the viewpoint of their optical characteristics and the like. As the active energy ray-curable composition used for such a cured resin, polyhydric acrylate and / or polyhydric methacrylate (hereinafter, referred to as polyhydric (meth) acrylate) in terms of handleability, curability, and the like. , Monoacrylate and / or monomethacrylate (hereinafter, referred to as mono (meth) acrylate), and a photopolymerization initiator using active energy rays as a main component are preferable. Representative polyvalent (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane poly (meth) acrylate, and the like. These are used alone or as a mixture of two or more. Also,
Examples of the mono (meth) acrylate include a mono (meth) acrylate of a monoalcohol and a mono (meth) acrylate of a polyol. In the latter case, when a metal type is used, a hydroxyl group is used. In order to reduce the difficulty of demolding from the metal mold that seems to be the effect,
It is better to use it in small quantities. When a metal type is used, it is preferable to use a small amount of (meth) acrylic acid and its metal salt because they have high polarity.

FIG. 5 shows a cylindrical lens type (roll type) 7.
FIG. 6 is an explanatory view of manufacturing a long lens sheet using the lens mold, and FIG. 6 is a perspective view of a lens mold 7 used therein.

The cylindrical lens mold 7 shown in FIGS. 5 and 6 has a lens unit in which a large number of lens unit transfer portions corresponding to a large number of lens units of a lens sheet are formed on the outer peripheral surface of a cylindrical roll 16. It has a transfer pattern 18. The lens mold 7 has a lens unit transfer portion made of a metal such as aluminum, brass, steel, or a synthetic resin such as a silicone resin, a polyurethane resin, an epoxy resin, an ABS resin, a fluorine resin, and a polymethylpentene resin. And those manufactured by Ni electroforming are used. From the viewpoint of heat resistance, strength, and the like, it is desirable to use a lens unit transfer portion or the like made of metal. It is preferable to apply a plating layer 32 of nickel, chromium, or the like to the surface of the lens mold to prevent various types of corrosion.

In the present invention, as shown in FIG. 7, a cylindrical lens mold 7 'in which a thin lens mold 35 on which a lens portion transfer pattern is formed is wound around the outer peripheral surface of a cylindrical roll 16 and fixed. Can also be used. Also,
In order to form the relaxation layer 1 more uniformly, the cylindrical lens mold 7 ′ is formed with a stepped portion having a thicker step portion 36 whose height in the radial direction is higher than the central portion at both ends in the axial direction on the outer peripheral surface. It is preferable to use a lens mold.

In FIG. 5, the lens mold 7 has a long translucent substrate 9 (FIG. 1) along the lens portion transfer pattern surface.
4 are supplied, and the active energy ray-curable composition 10 is continuously supplied from the resin tank 12 through the supply nozzle 13 between the lens mold 7 and the transparent substrate 9. Supplied. Outside of the translucent substrate 9 (lens type 7
The nip roll 8 for uniforming the thickness of the supplied active energy ray-curable composition 10 is provided on the side opposite to the side of (a). As the nip roll 8, a metal roll, a rubber roll, or the like is used. Further, in order to make the thickness of the active energy ray-curable composition 10 uniform, it is preferable that the nip roll 8 is processed with high accuracy in terms of roundness, surface roughness, and the like. In the case of a rubber roll, A rubber having a high hardness of 60 degrees or more is preferable. The nip roll 8 needs to accurately adjust the thickness of the active energy ray-curable composition 10, and the pressure adjustment mechanism 11 performs a pressure application operation. As the pressure adjusting mechanism 11, a hydraulic cylinder, a pneumatic cylinder, various screw mechanisms and the like can be used, but a pneumatic cylinder is preferable from the viewpoint of simplicity of the mechanism. The air pressure is controlled by a pressure regulating valve or the like.

The active energy ray-curable composition 10 supplied between the lens mold 7 and the translucent substrate 9 may be maintained at a constant viscosity in order to form the relaxation layer 1 to a constant thickness. preferable. Although the viscosity range varies depending on the thickness of the relaxation layer 1 to be formed, it is generally preferable that the viscosity be in the range of 20 to 3000 mPa · S under the temperature conditions (for example, 40 ° C.) during manufacture. Preferably 100 to 10
It is in the range of 00 mPa · S. When the viscosity of the active energy ray-curable composition 10 is less than 20 mPa · S, it is necessary to set the nip pressure extremely low or to extremely increase the molding speed for forming the relaxation layer 1. .
However, when the nip pressure is extremely reduced, the pressure adjusting mechanism 11
Tends to be unable to operate stably, and the unevenness of the thickness of the relaxing layer 1 tends to be caused. Further, when the molding speed is extremely increased, the irradiation amount of the active energy ray is insufficient, and the curing of the active energy ray-curable composition 10 tends to be insufficient. On the other hand, when the viscosity of the active energy ray-curable composition 10 exceeds 3000 mPa · S, the active energy ray-curable composition 10 does not sufficiently spread to the details of the lens-shaped lens portion transfer pattern, and the lens shape is accurately transferred. This tends to be difficult, defects tend to occur due to the incorporation of bubbles, and productivity tends to deteriorate due to an extremely low molding speed. In order to maintain the viscosity of the active energy ray-curable composition 10 at a constant level in this manner, a sheath heater, hot water, or the like is provided outside or inside the resin tank 12 so that the temperature of the active energy ray-curable composition 10 can be controlled. It is preferable to install heat source equipment such as a jacket.

After the active energy ray-curable composition 10 is supplied between the lens mold 7 and the translucent substrate 9, the active energy ray-curable composition 10 is mixed with the lens mold 7 and the translucent substrate 9. The active energy ray emission light source 14 is sandwiched between
Irradiates an active energy ray through the light-transmitting substrate 9 to polymerize and cure the active energy ray-curable composition 10,
The transfer of the lens portion transfer pattern formed on the lens mold 7 is performed. As the active energy ray irradiation device 14, a chemical lamp for chemical reaction, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a visible light halogen lamp, or the like is used. The irradiation amount of the active energy ray is 20
The integrated energy at a wavelength of 0 to 600 nm is 0.01 to 1
It is preferable that the concentration be 0 J / cm ² . Also,
The irradiation atmosphere of the active energy ray may be air or an inert gas atmosphere such as nitrogen or argon. Next, the lens sheet in which the light-transmitting substrate 9 and the lens portion formed of the polymerized and cured active energy ray-curable resin are integrated is released from the lens mold 7.

Here, in the present invention, the temperature of the outer peripheral surface of the cylindrical lens mold 7 is set within a range of a predetermined temperature of −3 ° C. to the predetermined temperature + 3 ° C., preferably a predetermined temperature of −2.
The temperature is controlled so as to fall within a range of from 0 ° C. to the predetermined temperature + 2 ° C., and more preferably within a range of a predetermined temperature of −1 ° C. to the predetermined temperature + 1 ° C. Such control can be performed by flowing a heat medium such as hot water through the cylindrical lens mold 7. FIGS. 8 and 9 are cross-sectional views of the lens mold 7 used for controlling the temperature uniformity of the outer peripheral surface. In the lens mold 7 of FIG. 8, a channel forming nest 7a is arranged inside the lens mold 7, and a heat medium of a desired temperature is supplied from the right side to the left side in the figure. The heat medium passes through a flow path formed in a hollow area between the lens mold 7 and the flow path forming nest 7a, and is discharged from the right side of the lens mold 7. In this way, by allowing the heat medium to flow through the heat medium flow passage P formed in the lens mold 7, the temperature of the outer peripheral surface of the lens mold 7 can be set within a desired temperature range of ± 3 ° C. it can. In the lens mold 7 of FIG. 9, a heating medium of a desired temperature is supplied leftward in the direction of the arrow from inside the right shaft portion of the lens mold 7 to the inside of the roll section, and the bent shape formed by the baffle plate 7b arranged in the roll section And then is discharged from the left shaft portion to the left in the direction of the arrow. This also allows the temperature of the outer peripheral surface of the lens mold 7 to be within a desired temperature range of ± 3 ° C.

In the present invention, the temperature of the active energy ray-curable composition 10 supplied between the cylindrical lens mold 7 and the light-transmitting substrate 9 is set at the above-mentioned predetermined temperature of −5 ° C. to the predetermined temperature. Temperature within a range of + 5 ° C, preferably a predetermined temperature of -3 ° C
Control is performed so as to be within the range of the predetermined temperature + 3 ° C.
Such control is performed by controlling the tank 12 of the active energy ray-curable composition, the supply nozzle 13 and the nozzle 13 and the tank 12.
This can be carried out by adjusting the temperature of the supply path 28 of the active energy ray-curable composition which connects the above. Tank 1
In order to maintain the temperature of the active energy ray-curable composition 10 in 2 within the above-mentioned temperature range, for example, a warm water jacket 12 a may be provided outside the tank 12. FIG. 5 shows a temperature controller 30 for controlling the temperature of the hot water. It is preferable to control the temperature of the supply path 28 and the supply nozzle 13 in the same manner. Alternatively, control for maintaining a predetermined temperature by electric heating may be performed. Thereby, the temperature of the supplied active energy ray-curable composition 10 can be set within a desired temperature range of ± 5 ° C. In FIG. 5, reference numeral 31 denotes a vacuum pump for reducing the pressure in the tank.

By controlling the temperature of the lens mold 7 and the temperature of the active energy ray-curable composition 10 as described above, the long lens sheet 19 having a wide width (eg, 400 mm width) can be formed to have a thickness (in particular, 400 mm). Active energy ray curable resin layer thickness)
It can be manufactured with good dimensional uniformity and good uniformity of optical properties. When the temperature of the active energy ray-curable composition 10 deviates from the desired temperature range of ± 5 ° C., the difference between the surface temperature of the lens mold and the active energy ray-curable composition 10 increases. Tends to increase, and the surface temperature of the lens mold 7 cannot be maintained uniformly. Thus, the difference in the surface temperature of the lens mold depending on the location (particularly, the difference between the vicinity of both ends and the vicinity of the center in the width direction) becomes large. As a result, the curing speed at the time of polymerizing and curing the resin by irradiation with active energy rays becomes different, and the uniformity of the film thickness of the obtained lens sheet 19 tends to decrease. In addition, the polymerization curing may be partially incomplete, in which case the difference in the refractive index of the obtained lens sheet depending on the location becomes large or whitish streaks are generated, and optical performance is impaired. Thus, the yield of the lens sheet production is reduced, and it is possible to cut out the obtained lens sheet into dimensions for actually configuring devices such as a prism sheet for a backlight and use it (that is, to effectively use it). The disadvantage is that the percentage of the (possible) area is reduced.

FIG. 10 is an explanatory view of the production of the double-sided lens sheet 29 as shown in FIG. 2. Basically, the formation of the lens portion on the translucent substrate 9 as shown in FIG. A first step S1 performed on the first surface and a second step S2 performed on the second surface are sequentially performed. That is, the first stage S1
Is the same as FIG. 5 described above, and the second step S2 is the first step S1
The same as the first step S1 except that the long sheet 19 having the prism portion formed on the first surface is used as the light-transmitting base material and that the lens mold 7 ′ has a required lens portion transfer pattern. It is. In the second stage S2, the first
Parts or members similar to the parts or members in step S1 are designated by the same reference numerals with the addition of “′”. Through the second step S2, the long double-sided lens sheet 29 is formed.

As shown in FIG. 2, the double-sided lens sheet 29 manufactured as described above has the lens portions 3 disposed on both sides of the light-transmitting substrate 2 via the relaxation layers 1 and 1 ′, respectively. , 4, a large number of prism rows each having a substantially triangular cross section are arranged in parallel, and the apex angle of the prism row formed on one lens unit 3 is in the range of 50 ° to 75 °. It is preferable that the apex angle of the prism array formed on the other lens portion 4 be in the range of 110 ° to 160 °.

FIG. 11 is a schematic view of a surface light source element using the above-described prism sheet. As shown, a linear light source 22 such as a fluorescent lamp, a light incident surface 23A facing the light source 22, and a light emitting surface 23B substantially orthogonal thereto.
And the double-sided prism sheet 21 placed on the light exit surface 23B of the light guide 23, a surface light source element is configured. The light guide 23 is formed of a substantially rectangular parallelepiped transparent plate, one main surface of which is a light exit surface 23B, and one side surface (end surface) is a light incident surface 23A. The linear light source 22 is arranged along the longitudinal direction in parallel with the light incident surface 23A. The prism sheet 21
Prism unit 3 having a prism array with a vertex angle of 50 ° to 75 °
Is preferably arranged so as to face the light exit surface 23B of the light guide 23, and is arranged such that the direction of the ridge line of the prism array is substantially parallel to the light incident surface 23A of the light guide 23. Is preferred. Further, on a back surface 23C of the light guide 23 opposite to the light exit surface 23B, a reflection layer 24 made of a reflection film, a reflection evaporation layer, or the like is disposed. In order to effectively introduce light from the light source 22 to the light guide 23, the light incident surface 23A of the light source 22 and the light guide 23 is covered with a reflector 25 made of a case or a film coated with a reflective agent on the inside. . Linear light source 22 and reflector 25
By attaching the same linear light source and reflector to the side surface (end surface) 23D opposite to the light incident surface 23A, this side surface 23D can also be used as the light incident surface.

Although the embodiment in which the double-sided prism sheet shown in FIG. 2 is used to constitute a surface light source element such as a liquid crystal display device has been described above, the single-sided prism sheet shown in FIG. It is used to form a surface light source element having the following configuration. In this case, when the prism sheet is arranged on the light guide such that the prism portion side is opposite to the light guide 23 side, the diffusion between the light guide and the prism sheet is usually performed. A sheet is placed. LC is a liquid crystal display element mounted on the surface light source element as described above.

[0042]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 As shown in FIG. 7, a pitch of 50 μm and a height of 25 μm were formed on the surface of a thin plate of brass (three kinds of JIS brass) having a thickness of 1.0 mm and a size of 400 mm × 690 mm.
m, a thin lens mold 35 having a prism portion transfer pattern formed thereon for transferring and forming a prism portion formed by arranging a large number of parallel isosceles triangular prism rows each having a vertical angle of 90 °. However, the thick step portion 36 was not formed. The thin plate lens mold 35 was subjected to electroless nickel plating. Next, in order to fix the thin plate lens mold 35, the diameter 2
A stainless steel cylindrical roll 16 having a length of 20 mm and a length of 450 mm was prepared, a thin lens mold 35 was wound around the outer peripheral surface of the cylindrical roll 16 and fixed with screws to obtain a cylindrical lens mold. As shown in FIG. 8, a flow path P for hot water flow is formed inside the lens mold, and the temperature of the hot water flowing through the flow path P is set as appropriate, so that the thin lens mold 35 is formed. The temperature of the outer peripheral surface of the entire width (total length in the axial direction)
Over a range of ± 1 ° C. during lens sheet shaping.

As shown in FIG. 5, N rubber having a rubber hardness of 80 ° is placed near the cylindrical lens mold 7 obtained as described above.
A rubber roll (nip roll) 8 made of BR was arranged. A 125 μm thick polyester film (light-transmitting substrate) 9 slightly wider than the cylindrical lens mold 7 was supplied between the cylindrical lens mold 7 and the rubber roll 8 and connected to the rubber roll 8. The polyester film 9 was nipped between the rubber roll 8 and the cylindrical lens mold 7 by a pneumatic cylinder (pressure adjusting mechanism) 11. The operating pressure of the pneumatic cylinder 11 at this time was 0.1 MPa. Air tube diameter 32 mm as pneumatic cylinder 11
SMC air cylinder was used. Further, an ultraviolet irradiation device (active energy ray irradiation device) 14 was installed below the cylindrical lens mold 7. The ultraviolet irradiation device 14
It has an ultraviolet intensity of 0 W / cm, an ultraviolet irradiation lamp manufactured by Western Quartz, having a capacity of 9.6 kW, a cold mirror type parallel light reflector, and a power supply. The UV-curable composition (active energy ray-curable composition) 10 was previously mixed with a refractive index adjusting component, a catalyst, and the like, and then charged into a resin tank 12. The resin tank 12 was made of stainless steel (SUS304) at all portions in contact with the ultraviolet curable composition 10. Further, it has a hot water jacket 12 a for controlling the liquid temperature of the ultraviolet curable composition 10, supplies hot water adjusted to 40 ° C. by the temperature controller 30 to the hot water jacket, The liquid temperature of the curable composition 10 was kept within a range of 40 ° C. ± 1 ° C. Further, the inside of the resin tank 12 was evacuated by the vacuum pump 31 to remove bubbles generated during charging.

The UV-curable composition 10 is as follows:
The viscosity was adjusted to 300 mPa · S / 40 ° C.

50 parts by weight of phenoxyethyl acrylate (Biscoat # 192 manufactured by Osaka Organic Chemical Industry) 50 parts by weight of bisphenol A-diepoxy-acrylate (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo) 2-hydroxy-2-methyl-1- Phenyl-propan-1-one (Darocur 1173 manufactured by Ciba Geigy) 1.5 parts by weight After the inside of the resin tank 12 was returned to normal pressure and the tank was sealed,
By applying an air pressure of 0.02 MPa to the resin tank 12 and opening a valve at the lower part of the resin tank 12, the ultraviolet curable composition 10 is passed through a pipe 28 temperature-controlled to 40 ° C. ± 1 ° C. The solution was supplied from a supply nozzle 13 whose temperature was controlled to 1 ° C. ± 1 ° C. onto one surface of a polyester film 9 which was nipped between a rubber roll 8 and a cylindrical lens mold 7. The temperature of the supplied ultraviolet ray curable composition was 40 ° C. ± 1 ° C. By flowing hot water of 40 ° C. at a flow rate of 40 liters / min through the hot water flow passage P in the lens mold 7, the temperature of the outer peripheral surface of the lens mold 7 is within a range of 40 ° C. ± 3 ° C. over the entire outer peripheral surface. It was made to become. The supply nozzle 13 is made of MN-18- manufactured by Iwashita Engineering Co., Ltd.
The company's AV101 valve fitted with a G13 needle was used. While rotating the cylindrical lens mold 7 in the direction of the arrow at a peripheral speed of 3.5 m / min with a Mitsubishi Electric 0.2 kW geared motor (reduction ratio 1/200), the ultraviolet curable composition 1 was used.
While the layer 0 is in a layer state sandwiched between the cylindrical lens mold 7 and the polyester film 9, ultraviolet rays are irradiated from the ultraviolet irradiation device 14 to polymerize and cure the ultraviolet curable composition 10, and the prism portion of the cylindrical lens mold 7 is formed. The transfer pattern was transferred. Thereafter, the mold was released from the cylindrical lens mold 7 to obtain a long prism sheet (lens sheet).

The cross section of the obtained prism sheet was scanned with a scanning electron microscope (JSM-840A, manufactured by JEOL Ltd., 2000).
As a result, the height and the apex angle of the prism array and the arrangement pitch thereof are almost as designed, and the thickness between the polyester film 9 and the prism portion is about 2 μm (8% of the lens height). And the deformation of the prism shape due to polymerization shrinkage was hardly observed.

In addition, the center position in the width direction of the long sheet (this corresponds to the center position in the longitudinal direction of the lens mold), and six positions (each 30 mm) from the center position (C) toward the left end edge ( L1 to L6) and 30 mm toward the right edge
At each of the six positions (R1 to R6), the total thickness of the prism portion height H and the relaxation layer thickness (that is, the thickness of the ultraviolet curable resin layer) was measured in the longitudinal direction of the long sheet by 69.
The measurement was performed at 10 points each for 0 mm, and the average of the measured values at 10 points was obtained for each position in the width direction. As a result, as shown in Table 1 below, it was found that there was almost no difference in thickness between the vicinity of the center position and the vicinity of both edge positions.

[0049]

[Table 1] Further, as shown in FIG. 11, the obtained prism sheet is placed on a light exit surface 23B of an acrylic resin light guide 23 having a cold cathode tube 22 disposed on a side face thereof through a light diffusion film via a light diffusion film. The light guide 2 is placed so that it faces upward.
3. The other side surface 23D and back surface 23C are
And the cold cathode tube 22 was turned on to check the appearance. As a result, no optical defect such as a spot-like or streak-like pattern was found, and the optical characteristics were excellent.

Comparative Example 1 Pipe 28 and Supply Nozzle 13
A long lens sheet was manufactured in the same manner as in Example 1 except that the temperature control was not performed. The temperature of the ultraviolet curable composition 10 supplied to the lens mold 7 was 34.0 ° C.

The thickness of the ultraviolet curable resin layer of the obtained prism sheet was measured in the same manner as in Example 1. As shown in Table 2 below, the vicinity of the center position and the vicinity of the both end positions were determined. It turned out that there is a considerable difference in thickness between the two.

[0052]

[Table 2] Further, as shown in FIG. 11, the obtained prism sheet is placed on a light exit surface 23B of an acrylic resin light guide 23 having a cold cathode tube 22 disposed on a side face thereof through a light diffusion film via a light diffusion film. The light guide 2 is placed so that it faces upward.
3. The other side surface 23D and back surface 23C are
And the cold cathode tube 22 was turned on to check the appearance. As a result, an optical defect having a streak-like pattern was partially observed, and the optical characteristics were poor.

[Comparative Example 2] A lens mold 7 having no hot water flow passage P was used as the lens mold 7, except that
In the same manner as in Example 1, a long lens sheet was manufactured.
The temperature distribution on the outer peripheral surface of the lens mold 7 was 40.0 ° C. at the central position in the width direction, but was 36.8 ° C. and 36.4 ° C. at the left and right edge positions.

The thickness of the ultraviolet curable resin layer of the obtained prism sheet was measured in the same manner as in Example 1. As shown in Table 3 below, the vicinity of the center position and the vicinity of both end edges were measured. It turned out that there is a considerable difference in thickness between the two.

[0055]

[Table 3] Further, as shown in FIG. 11, the obtained prism sheet is placed on a light exit surface 23B of an acrylic resin light guide 23 having a cold cathode tube 22 disposed on a side face thereof through a light diffusion film via a light diffusion film. The light guide 2 is placed so that it faces upward.
3. The other side surface 23D and back surface 23C are
And the cold cathode tube 22 was turned on to check the appearance. As a result, an optical defect having a streak-like pattern was partially observed, and the optical characteristics were poor.

[Embodiment 2] As shown in FIG.
A hard copper plating layer 32 having a Vickers hardness of 200 was applied to a thickness of 100 μm on the outer peripheral surface of the iron core roll 16 having a length of 20 mm and a length of 450 mm. On this hard copper plating layer 32, a prism portion transfer pattern for transferring and forming a prism portion formed by arranging a large number of parallel isosceles triangular prism rows having a pitch of 50 μm, a height of approximately 39 μm, and a vertex angle of 65 ° is formed. A first cylindrical lens mold 7 was prepared. The prism portion transfer pattern had a large number of parallel prism row transfer portions extending in the circumferential direction of the core roll 16.

On the other hand, a 50 μm pitch was applied to the surface of a thin plate of brass (three kinds of JIS brass) having a thickness of 1 mm and a size of 700 × 850 mm.
A prism portion transfer pattern for transferring and forming a prism portion formed by arranging a large number of isosceles triangular prism rows having a cross section of m, a height of about 12 μm, and a vertex angle of 130 ° was formed, and a thin plate lens mold was prepared. This thin lens mold was electroless nickel plated with a thickness of 1 μm to prevent various types of corrosion. Next, the thin plate lens mold 35 is tilted by 15 ° with respect to the direction of the prism array transfer portion and cut out into a rectangular shape having a size of 400 mm × 690 mm to obtain the thin plate lens mold 35 as shown in FIG. Was. However, the thick step portion 36 was not formed. To fix the thin plate lens mold 35, a stainless steel core roll 16 having a diameter of 220 mm and a length of 450 mm is prepared, the thin plate lens mold 35 is wound on the outer peripheral surface of the core roll 16, and fixed with screws. A second wound cylindrical lens mold 7 'as shown in FIG. 7 was prepared.

As shown in FIG. 10, the first cylindrical lens mold 7 obtained as described above is connected to the first stage lens forming section S.
1, a second wound cylindrical lens mold 7 'was set in the second-stage lens forming portion S2. In addition, NBR rubber rolls 8, 8 'having a rubber hardness of 80 ° were arranged close to the first and second cylindrical lens molds 7, 7', respectively. A thickness 1 slightly wider than the first cylindrical lens mold 7 between the first cylindrical lens mold 7 and the first rubber roll 8.
88 μm polyethylene terephthalate film (PE
T film) (translucent base material) 9 is passed along the first cylindrical lens mold 7, and the first rubber roll 8 and the first rubber roll 8 are connected by the first pneumatic cylinder 11 connected to the first rubber roll 8. The PET film 9 was nipped with the cylindrical lens mold 7. At this time, the operating pressure of the first pneumatic cylinder 11 was 0.1 MPa. First pneumatic cylinder 11
An SMC air cylinder having an air tube diameter of 32 mm was used. Further, a first ultraviolet irradiation device 14 was installed below the first cylindrical lens mold 7. The first ultraviolet irradiation device 14 has an ultraviolet intensity of 120 W / cm, and includes an ultraviolet irradiation lamp manufactured by Western Quartz, having a capacity of 9.6 kW, a cold mirror type parallel light reflector, and a power supply. The first ultraviolet-curable composition 10 was previously mixed with a refractive index adjusting component, a catalyst, and the like, and then charged into the first resin tank 12. The first resin tank 12
All parts in contact with the first ultraviolet curable composition 10 were made of stainless steel (SUS304). Also, the first
A warm water jacket 12a is provided to control the liquid temperature of the ultraviolet curable composition 10 of the first embodiment.
The hot water adjusted to 40 ° C. by the hot water jacket 12
a, and the ultraviolet curable composition 1 in the resin tank 12
The liquid temperature of 0 was kept within the range of 40 ° C. ± 1 ° C. further,
The foam generated at the time of charging is firstly pumped by the first vacuum pump 31.
The inside of the resin tank 12 was degassed and removed by applying a vacuum.

The first UV-curable composition 10 was as follows, and the viscosity was adjusted to 300 mPa · S / 40 ° C.

Phenoxyethyl acrylate 50 parts by weight (Biscoat # 192 manufactured by Osaka Organic Chemical Industry Co., Ltd.) Bisphenol A-diepoxy-acrylate 50 parts by weight (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 2-hydroxy-2-methyl-1- Phenyl-propan-1-one (Darocur 1173, Ciba-Geigy) 1.5 parts by weight Once the inside of the first resin tank 12 was returned to normal pressure, the tank was sealed, and then 0.1% by weight was placed in the first resin tank 12. 02MPa
The first ultraviolet curable composition 10 is opened by applying air pressure to the first resin tank 12 and opening a valve at the bottom of the first resin tank 12.
Through a first pipe 28 temperature-controlled to 40 ° C. ± 1 ° C., and from a first supply nozzle 13 also temperature-controlled to 40 ° C. ± 1 ° C., a first rubber roll 8 and a first cylindrical lens mold. 19 and the first cylindrical lens mold 7. The temperature of the supplied first ultraviolet curable composition was 40 ° C. ± 1 ° C. By flowing hot water of 40 ° C. at a flow rate of 40 liters / min through the hot water flow passage P in the lens mold 7, the temperature of the outer peripheral surface of the lens mold 7 is within a range of 40 ° C. ± 3 ° C. over the entire outer peripheral surface. It was made to become. As the first supply nozzle 13, an AV101 valve manufactured by Iwashita Engineering Co., Ltd. equipped with a MN-18-G13 needle was used. Mitsubishi Electric 0.2kW geared motor (reduction ratio 1/20
1), while rotating the first cylindrical lens mold 7 in the direction of the arrow at a peripheral speed of 2.0 m / min, the first ultraviolet-curable composition 10 is mixed with the first cylindrical lens mold 7 and the PET film 9. While being in the layer state sandwiched between the first ultraviolet curable composition 10 and the first ultraviolet curable composition 10, the first ultraviolet curable composition 10 is polymerized and cured, and the one surface (the first A first prism portion was formed on (1 surface).

Next, a PET film 9 having a first presumed portion formed on one surface (that is, a single-sided prism sheet 19) is placed on a second wound cylindrical lens mold 7 'and a second rubber roll 8'. During this time, the PET film 9 was supplied along the second wrapped cylindrical lens mold 7 'so that the other surface of the PET film 9 was in contact with the lens mold 7'. The PET film 9 was nipped between the second rubber roll 8 'and the second wound cylindrical lens mold 7' by the second pneumatic cylinder 11 'connected to the second rubber roll 8'. At this time, the operating pressure of the second pneumatic cylinder 11 'was 0.1 MPa. The second ultraviolet-curable composition 10 'was previously mixed with a refractive index adjusting component, a catalyst, and the like, and then charged into a second resin tank 12'. Further, bubbles generated at the time of charging were defoamed and removed by bringing the second resin tank 12 'into a vacuum state by the second vacuum pump 31'. A second temperature controller 30 ′ is provided in the second resin tank 12 ′ similarly to the first resin tank 12.
, And the same temperature control was performed.

The second ultraviolet-curable composition 10 'was as follows, and the viscosity was adjusted to 150 mPa · S / 40 ° C.

70 parts by weight of phenoxyethyl acrylate (Biscoat # 192 manufactured by Osaka Organic Chemical Industry Co., Ltd.) 30 parts by weight of bisphenol A-diepoxy-acrylate (Epoxyester 3000A manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 2-hydroxy-2-methyl-1- Phenyl-propan-1-one (Darocur 1173 manufactured by Ciba-Geigy) 1.5 parts by weight Once the inside of the second resin tank 12 ′ is returned to normal pressure, the tank is closed, and then the second resin tank 12 ′ is put into the second resin tank 12 ′. 0.02M
By applying an air pressure of Pa and opening the valve at the bottom of the second resin tank 12 ′, the second ultraviolet curable composition 10 ′ is cooled to 40 ° C. ± 1 ° C. in the second pipe 2.
Through 8 ', the second is also temperature controlled to 40 ° C ± 1 ° C
P which is nipped between the second rubber roll 8 'and the second wound cylindrical lens mold 7' from the supply nozzle 13 'of FIG.
It was supplied between the ET film 9 and the second wound cylindrical lens mold 7 '. The temperature of the supplied second ultraviolet curable composition was 40 ° C. ± 1 ° C. By flowing hot water of 40 ° C. at a flow rate of 40 liter / min through the hot water flow passage P in the lens mold 7 ′, the temperature of the outer peripheral surface of the lens mold 7 ′ is 40 ° C. ± 3 ° C. over the entire outer peripheral surface. It was made to be within the range. While rotating the second wound cylindrical lens mold 7 ′ in the direction of the arrow at a peripheral speed of 2.0 m / min with a Mitsubishi Electric 0.2 kW geared motor 33 (reduction ratio 1/200), While the curable composition 10 ′ is in a layer state sandwiched between the second wound cylindrical lens mold 7 ′ and the PET film 9, ultraviolet light is irradiated from the second ultraviolet irradiation device 14 ′, The second ultraviolet curable composition 10 ′ is polymerized and cured, and the second prism portion is formed on the other surface (the second prism portion) of the PET film 9.
Surface). After that, the mold is released from the second wound cylindrical lens mold 7 ', and the intersection angle between the prism rows on both sides is 15
° both-sided prism sheet 29 was obtained.

A section of the obtained prism sheet was taken with a scanning electron microscope (JSM-840A, 2000, manufactured by JEOL Ltd.).
Times), the height and the apex angle of the prism array and the arrangement pitch thereof are almost as designed, and the apex angle is 65 °.
On the side of the prism surface, a relaxation layer having a thickness of 2 μm (5% of the lens height) is formed between the PET film 9 and the prism portion.
A relaxation layer having a thickness of 1 μm (8% of the lens height) was formed between the T film 9 and the prism portion, and almost no deformation of the prism shape due to polymerization shrinkage was observed.

With respect to the obtained prism sheet, the thickness of the ultraviolet-curable resin layer (the total thickness of the resin layers on both sides) was measured in the same manner as in Example 1. As shown in Table 4 below, It was found that there was almost no difference in thickness between the vicinity of the center position and the vicinity of both edge positions.

[0066]

[Table 4] Further, as shown in FIG. 11, the obtained prism sheet is oriented such that the prism surface having an apex angle of 65 ° faces downward on the light emitting surface 23B of the acrylic resin light guide 23 having the cold cathode tubes 22 arranged on the side surfaces. And the other side 2 of the light guide 23
The 3D and back surface 23C were covered with a reflection sheet 24, and the cold cathode tubes 22 were turned on to check the appearance. As a result, no optical defect such as a spot-like or streak-like pattern was found, and the optical characteristics were excellent.

Comparative Example 3 A long lens sheet was manufactured in the same manner as in Example 2 except that the temperature control of the pipes 28, 28 'and the supply nozzles 13, 13' was not performed. UV curable composition 10, which is supplied to lens molds 7, 7 '
The temperature at 10 ′ was 34.0 ° C.

The thickness of the ultraviolet-curable resin layer of the obtained prism sheet was measured in the same manner as in Example 2. As shown in Table 5 below, the vicinity of the center position and the vicinity of both end edge positions were determined. It turned out that there is a considerable difference in thickness between the two.

[0069]

[Table 5] Further, as shown in FIG. 11, the obtained prism sheet is oriented such that the prism surface having an apex angle of 65 ° faces downward on the light emitting surface 23B of the acrylic resin light guide 23 having the cold cathode tubes 22 arranged on the side surfaces. And the other side 2 of the light guide 23
The 3D and back surface 23C were covered with a reflection sheet 24, and the cold cathode tubes 22 were turned on to check the appearance. As a result, an optical defect having a streak-like pattern was partially observed, and the optical characteristics were poor.

Comparative Example 4 A long lens sheet was manufactured in the same manner as in Example 1 except that the lens molds 7 and 7 ′ were not provided with a hot water flow passage P therein. The temperature distribution on the outer peripheral surface of the lens mold 7 was 40.0 ° C. at the center position in the width direction, but was 35.8 ° C. and 35.4 ° C. at the left and right edge positions. The temperature distribution on the outer peripheral surface of the lens mold 7 ′ was 39.8 ° C. at the central position in the width direction, but was 35.5 ° C. and 35.2 ° C. at the left and right edge positions.

The thickness of the ultraviolet-curable resin layer of the obtained prism sheet was measured in the same manner as in Example 2. As shown in Table 6 below, the vicinity of the center position and the vicinity of both ends were measured. It turned out that there is a considerable difference in thickness between the two.

[0072]

[Table 6] Further, as shown in FIG. 11, the obtained prism sheet is oriented such that the prism surface having an apex angle of 65 ° faces downward on the light emitting surface 23B of the acrylic resin light guide 23 having the cold cathode tubes 22 arranged on the side surfaces. And the other side 2 of the light guide 23
The 3D and back surface 23C were covered with a reflection sheet 24, and the cold cathode tubes 22 were turned on to check the appearance. As a result, an optical defect having a streak-like pattern was partially observed, and the optical characteristics were poor.

[0073]

As described above, according to the present invention, the temperature of the outer peripheral surface of the lens mold is controlled to be uniform near the predetermined temperature, and the deviation of the temperature of the active energy ray-curable composition from the predetermined temperature is determined. By performing the control to be within the range, the unevenness in the height of the lens portion and the thickness of the active energy ray-curable resin layer is small, and a long lens sheet with little variation in the optical characteristics depending on the place is continuously manufactured. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a single-sided lens sheet manufactured by a method of the present invention.

FIG. 2 is a schematic sectional view showing an example of a double-sided lens sheet manufactured by the method of the present invention.

FIG. 3 is a schematic sectional view showing an example of a double-sided lenticular lens sheet.

FIG. 4 is a schematic sectional view showing an example of a double-sided lenticular lens sheet.

FIG. 5 is an explanatory diagram of manufacturing a single-sided lens sheet using a cylindrical lens mold.

FIG. 6 is a perspective view of a lens mold.

FIG. 7 is a perspective view of a lens mold.

FIG. 8 is a sectional view of a lens mold.

FIG. 9 is a sectional view of a lens mold.

FIG. 10 is an explanatory diagram of manufacturing a double-sided lens sheet using a cylindrical lens mold.

FIG. 11 is a schematic perspective view showing a surface light source element using a double-sided lens sheet.

[Explanation of symbols]

 Reference Signs List 1, 1 'relaxation layer 2 light-transmitting substrate 3, 4, 5, 6 lens portion 7, 7' cylindrical lens type 7a channel forming nest 7b baffle plate 8 nip roll 9 light-transmitting substrate 10 active energy ray Curable composition 11 Pressure adjusting mechanism 12 Resin tank 12a Hot water jacket 13 Supply nozzle 16 Cylindrical roll 18 Lens portion transfer pattern 19 Single-sided lens sheet 21 Double-sided lens sheet 29 Double-sided lens sheet 30 Temperature controller 35 Thin plate lens type 36 Step B Light absorbing layer H, H 'Lens height S1 First stage S2 Second stage P Heat medium passage

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // G02F 1/1335 G02F 1/1335 B29L 11:00 B29L 11:00 F-term (Reference) 2H042 BA04 BA14 BA15 BA20 2H091 FA21X FA21Z FA28X FA28Z FC01 LA11 LA12 4F202 AA21 AA44 AC05 AD05 AD08 AH75 AR06 CA01 CB02 CB12 CN01 CN05 CN12 4F204 AA21 AA44 AC05 AD05 AD08 AH75 AR06 EA03 EB02 EB12 EE10 EK10 EK10

Claims (9)

[Claims] An active energy ray-curable composition is supplied between the outer peripheral surface of a cylindrical lens type having an outer peripheral surface on which a lens portion transfer pattern is formed and one surface of a light-transmitting substrate. Irradiating an active energy ray through the translucent substrate to cure and shape the composition to form a lens portion made of an active energy ray-cured resin having a shape corresponding to the lens portion transfer pattern; A lens sheet comprising a lens portion including a repetitive arrangement of lens units on at least one surface of the light-transmitting substrate continuously by releasing the lens portion and the light-transmitting substrate from the lens mold integrally Controlling the temperature of the outer peripheral surface of the cylindrical lens mold so as to be within a range of a predetermined temperature of −3 ° C. to the predetermined temperature + 3 ° C. A lens for controlling the temperature of the active energy ray-curable composition supplied between the lens and the optical substrate so as to be in the range of the predetermined temperature −5 ° C. to the predetermined temperature + 5 ° C. Sheet manufacturing method. 2. The lens sheet according to claim 1, wherein the temperature of the outer peripheral surface of the cylindrical lens mold is controlled by circulating a heat medium in the cylindrical lens mold. Production method. 3. The method of controlling the temperature of the active energy ray-curable composition comprises connecting a tank of the active energy ray-curable composition, a supply nozzle, and the supply nozzle to a tank of the active energy ray-curable composition. The method for producing a lens sheet according to claim 1, wherein the supply is performed by adjusting the temperature of a supply path of the active energy ray-curable composition. 4. The lens sheet according to claim 1, wherein the transparent substrate has a lens portion made of an active energy ray-curable resin on the other surface. Production method. 5. In a state where the active energy ray-curable composition is sandwiched between the light-transmitting substrate and the lens mold,
The method for producing a lens sheet according to claim 1, wherein the composition is irradiated with an active energy ray. 6. A nip pressure of a nip roll disposed so as to face the other surface of the light-transmitting substrate by adjusting a nip pressure by a pressure adjusting mechanism, so that the nip pressure is adjusted between the lens portion and the light-transmitting substrate. The method for producing a lens sheet according to any one of claims 1 to 5, wherein a relaxation layer made of an active energy ray-curable resin is formed. 7. The active energy ray-curable composition 4
The method for producing a lens sheet according to any one of claims 1 to 6, wherein the viscosity at 0 ° C is 20 to 3000 mPa · S. 8. The lens-type lens portion transfer pattern is for forming, by transfer, a lens portion including a large number of lens units each having a prism array having a substantially triangular cross section. A method for manufacturing the lens sheet according to claim 1. 9. The lens-type lens unit transfer pattern for transferring a lens unit including a large number of lenticular lens units by transfer. A method for producing the lens sheet described above.