JP5272531B2 - Mold, imprint molded product and surface light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide imprint molded products of an optical film attaining high-brightness property by eliminating brightness unevenness using a mold. <P>SOLUTION: In the mold in which a plurality of linear grooves lines parallel adjacent to each other on the surface thereof, crosssectional recess shapes in an optional crosssection perpendicular to the longitudinal direction of the respective grooves form parts of linear symmetrical curved lines in which the angle of the acute angle made between the tangent line at the point on the curved line and the line parallel to the linear symmetrical axis as departing from the linear symmetric line gradually decreases, the linear symmetrical axes of the respective crosssectional recess shapes are parallel, at least one angle in all of the cross point sections is at most 25&deg;, each of the same is different, and the angle of the cross point section changes as the crosssection moves along the longitudinal direction of the grooves in the optional adjacent grooves, provided that the angle of the acute angle made between the tangent line in the cross point section of one crosssectional recess shape and the straight line parallel to the linear symmetrical axis is &theta;<SB>1</SB>and the angle of the acute angle made between the tangent line in the cross point section of the other crosssectional recess shape and the straight line parallel to the linear symmetrical axis is &theta;<SB>2</SB>in the cross point section of the crosssectional recess shapes of the adjacent grooves. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is a mold for pressing a resin or the like to form an arbitrary shape on the surface of the resin or the like, and particularly suitable for forming an imprint molded product of an optical film by an imprint method. About.

  In recent years, a liquid crystal display used as a display device such as a personal computer, a television, or a mobile phone is not itself a light emitter, and can be displayed by irradiating light from the back surface using a surface light source. The surface light source employs a structure called a sidelight type or direct type backlight unit.

  In particular, direct-type backlight units used in televisions and the like have a structure in which a large number of light sources such as cold-cathode tubes are arranged in parallel, so there is a large difference in brightness between the position directly above the light source and the position where it is not. There is a problem that it is likely to occur and is recognized as luminance unevenness. For this reason, in order to irradiate the entire screen uniformly and with higher brightness, a light diffusing plate called a milky white plate in which diffusible particles are dispersed in acrylic resin or the like is installed on the upper surface of the light source. In addition, a diffusion sheet and a prism sheet are arranged in an overlapping manner.

  The demand for higher brightness of surface light sources tends to increase year by year. As the means, for example, proposals have been made regarding an increase in the number of lamps, an improvement in output, or a film having an uneven shape on the surface. However, the former method causes a significant cost increase and is inefficient. Accordingly, as the latter film shape proposals, those having a cylindrical lens portion in a stripe shape (see Patent Document 1) and those having a rugby ball shape (see Patent Document 2) have been proposed. However, the current situation is that it does not have sufficiently high brightness and uniformity, and measures such as increasing the number of prism sheets etc. may be taken to compensate for this, but in this case the display will be made thinner It is against the further request item. Further, when a plurality of optical sheets are used in an overlapping manner, there arises a problem that moire fringes are generated due to the interference effect. In order to solve this problem, a method has been proposed in which the height, pitch, and the like of the prism concavo-convex shape are randomly distributed (see Patent Document 3).

  Therefore, as a shape that can efficiently eliminate luminance unevenness and increase the uniformity on the screen while achieving high luminance characteristics, a shape that repeatedly has part of a semicircular or elliptical curve has been proposed. (See Patent Document 4).

  In addition, as a method for imparting a fine uneven three-dimensional shape to the surface of a film or the like, the uneven shape is applied to the film by pressing a mold having a shape obtained by inverting the desired fine uneven three-dimensional shape onto the film. A thermal imprint method for transfer (see Patent Document 5) or a photocurable resin is applied on a film, and a mold having a desired fine irregular shape is pressed against the photocurable resin portion, and the mold is pressed. A photo-imprinting method (see Patent Document 6) is known in which a photocurable resin is cured by irradiating ultraviolet light from a direction opposite to the surface to be cured, and the mold is released to transfer the uneven shape onto a film or the like. It has been.

In addition, as a method of manufacturing the mold, the surface of the mold is cut by an NC processing machine capable of three-dimensional processing using a processing tool having the same shape as a desired fine three-dimensional cross section. A method of forming a pattern shape is more frequently used than before.
JP 2002-62528 A JP 2002-107510 A JP 2003-140126 A Japanese Patent Application No. 2006-339515 JP 2005-199455 A JP 2005-354017 A

  When grooves having substantially the same concave cross section on the mold surface are cut in parallel and the entire mold surface is cut, the ridge lines formed by the intersections of adjacent grooves are arranged on substantially the same plane. Here, when the thickness of the intersection portion of adjacent cross-sectional concave shapes becomes thin, and the acute angle formed by the perpendicular to this plane and the tangent to the cross-sectional concave shape at the intersection portion is 25 ° or less, the intersection portion falls or Fluctuation, etc. will occur. Further, since it is difficult to process the intersection portion thinly and with high accuracy, a flat portion may remain between adjacent grooves. As a result, there is a problem that a desired pattern shape cannot be formed. In addition, there is a problem that such a defect of the mold is recognized as a striped pattern or a color on the appearance and as a brightness unevenness when an imprint molded product is created.

In order to solve the above problems, the mold of the present invention has the following configuration. That is,
A mold in which a shape in which a plurality of straight grooves are arranged in parallel with each other is formed on the surface,
The concave shape of the cross section at the cutting plane perpendicular to the longitudinal direction of each groove is a part of a line-symmetrical curve, and the curve forms a tangent at a point on the curve and a line parallel to the line-symmetrical axis as it moves away from the line-symmetrical axis. It is a curve where the acute angle gradually decreases,
The line symmetry axes of the concave sections are parallel,
The intersection of adjacent concave grooves is defined as the intersection, and the acute angle between the tangent at the intersection of one of the grooves and the straight line parallel to the axis of symmetry is θ ₁ , and the intersection of the other concave When an acute angle formed by a tangent line at the portion and a straight line parallel to the axis of line symmetry is θ ₂ ,
In the arbitrary cut surface, at least one of θ ₁ and θ ₂ at all the intersections is 25 ° or less,
In any cut surface, θ ₁ of all adjacent intersections are different, and θ _{2 of} all adjacent intersections are different,
In the arbitrary adjacent groove, the mold in which θ ₁ and θ _{2 at the} intersections change as the cut surface moves along the longitudinal direction of the groove.

  The imprint molded product of the present invention is formed using the mold of the present invention, and the surface light source of the present invention comprises the imprint molded product of the present invention and a light emitting means.

  ADVANTAGE OF THE INVENTION According to this invention, even if the thickness of the intersection part of an adjacent groove | channel is thin, it can fall to an intersection part and there can be provided the metal mold | die which does not have a flat part between adjacent grooves. More specifically, at the intersection of adjacent cross-sectional concave shapes, even if the acute angle between the tangent line at the intersection of at least one concave cross-section and the line parallel to the line symmetry axis is 25 ° or less, It is possible to provide a mold that does not fall down or fluctuate and has no flat portion between adjacent grooves. In addition, since the appearance is a random pattern, processing defects are not noticeable, and striped patterns and coloring on the appearance can be suppressed.

  Furthermore, if the metal mold | die of this invention is used, the imprint molded product of the optical film which can achieve a high-intensity characteristic can be formed, eliminating a brightness nonuniformity efficiently and raising the uniformity on a screen. Further, when the imprint molded product is used while being overlapped with another sheet such as a prism sheet, it is possible to prevent the occurrence of moire fringes caused by the interference effect.

  Hereinafter, the mold, imprint molded product, and surface light source of the present invention will be described in more detail with reference to the drawings.

The mold of the present invention is a mold in which a plurality of linear grooves as shown in FIG. 1 are arranged in parallel with each other, a so-called concave stripe pattern shape formed on the surface,
The concave portion of the cross section in the cutting plane perpendicular to the longitudinal direction of each groove is a portion 101 of a curved line, and the curved line forms a tangent at a point on the curved line and a line parallel to the linearly symmetric axis as it moves away from the line symmetric axis It is a curve where the acute angle gradually decreases,
An intersection of adjacent concave sections of grooves is defined as an intersection, and an acute angle formed by a tangent at the intersection of one of the concave sections and a line parallel to the line symmetry axis is θ ₁ , and the other concave section is When the angle between the acute angle at the intersection and the line symmetry axis is θ ₂ ,
In any cut surface, at least one of θ ₁ and θ ₂ at all the intersections is 25 ° or less,
In any cut surface, θ _{1 of} any adjacent intersection is different, and θ _{2 of} all adjacent intersections are different,
In any adjacent groove, the die 100 is such that θ ₁ and θ _{2 at the} intersections vary as the cut surface moves along the longitudinal direction of the groove.

In the present invention, by making the angles θ ₁ and θ ₂ within the range of 5 ° to 35 °, out of the light incident in the oblique direction from the fluorescent tube of the backlight, the light is emitted strongly in the oblique direction opposite to the incident direction. In the literature 3, it is possible to reduce the ratio of light to be emitted and to bend light incident in an oblique direction from the fluorescent tube in the front direction, and to improve luminance without increasing luminance unevenness. This is in accordance with the idea, and is intended to realize a large-size cutting at 25 ° or less, which makes it difficult to manufacture a mold, even in the angle of 5 ° to 35 °.

  The metal mold | die of this invention is a metal mold | die with which the shape in which the linear groove | channel was arranged in contact in parallel was formed in the surface. Since each groove is in contact, there is no substantial flat portion between adjacent grooves. Here, the substantially flat part means that when an imprint molded product of an optical film is formed using the mold of the present invention, light emitted from the fluorescent tube is straightly transmitted at a place formed by the flat part. The part that will end up. By eliminating the substantially flat portion, it is possible to prevent the light emitted from the fluorescent tube from being transmitted in a straight line and to prevent uneven brightness.

  Each groove in the present invention is a part of a curved line having a line-symmetrical concave shape in a cross section perpendicular to the longitudinal direction of the groove, and the curved line is symmetric with a tangent at a point on the curved line as the distance from the line-symmetrical axis increases. The acute angle formed by the line parallel to the axis is gradually reduced. When the concave shape of the cross section is a curve whose acute angle gradually decreases as it moves away from the line symmetry axis, when the imprint molded product of the optical film is formed using the mold of the present invention, the light incident at various angles It is possible to have a tangential angle for bending the lens in the front direction, and to reduce luminance unevenness. Further, when the concave shape of the cross section is line symmetric, when the imprint molded product of the optical film is formed using the mold of the present invention, the convex shape of the surface of the imprint molded product is also a line symmetric curve. Can be seen in the same way. Examples of such a curved shape include, but are not necessarily limited to, a semicircle, a semi-ellipse, a parabola, a hyperbola, a trigonometric function, or a predetermined part constituting such a curve.

Moreover, the metal mold | die of this invention is a shape where the cross-sectional concave shape is repeated with the pitch of 1 micrometer-1 mm. Preferably, the cross-sectional concave shape having a height of 1 μm to 200 μm is repeated at a pitch of 1 μm to 200 μm. Here, as shown in FIG. 5, the pitch is the distance between adjacent line-symmetrical axes having concave concave shapes. The pitch may be a fixed value or may be changed instead of a fixed value. The height, as shown in FIG. 4, the distance h ₁ from a plane perpendicular to bottom 6 as line symmetry axis to the intersection point 1, is that the average value of the distance h ₂ from the plane to the intersection 2 . When the pitch is less than 1 μm, the influence of diffracted light becomes large, and when an imprint molded product of an optical film is formed using the mold of the present invention, a desired optical effect cannot be obtained. When the pitch is 1 mm or more, the rigidity of the mold base material is increased, so that it is possible to perform a desired high aspect shape cutting process without performing a random stripe process.

The angles θ ₁ and θ ₂ in the present invention are angles as shown in detail in FIG. That is, with respect to the cross-sectional concave shape in the cutting plane perpendicular to the longitudinal direction of the groove, the line 3 parallel to the line symmetry axis 10 of the cross-sectional concave shape at the intersection 1 of the adjacent cross-sectional concave shape and the two adjacent cross-sectional concaves at the intersection 1 The acute angles θ ₁ and θ ₂ formed by the tangent lines 4 and 5 of the shape.

In the present invention, i) at an arbitrary cutting plane perpendicular to the longitudinal direction of the groove, at least one of θ ₁ and θ ₂ at all the intersections is 25 ° or less, and ii) an arbitrary perpendicular to the longitudinal direction of the groove In the cut surface, all adjacent intersections have different θ ₁ , and all adjacent intersections have different θ ₂ , and iii) in any adjacent groove, in the longitudinal direction of the groove As the vertical cut surface moves along the longitudinal direction of the groove, θ ₁ and θ _{2 at the} intersections change.

  A specific mold shape satisfying such requirements is, for example, a shape as shown in FIG. The X direction in FIG. 1A is a direction perpendicular to the longitudinal direction of the groove and the line symmetry axis, the Y direction is the longitudinal direction of the groove, and the Z direction is a direction parallel to the line symmetry axis. 1A is a perspective view of a mold, FIG. 1B is a cross-sectional shape at a cutting plane (XZ plane) perpendicular to the longitudinal direction of the groove, and FIG. 1C is parallel to the longitudinal direction of the groove and includes an axis of line symmetry. It is a cross-sectional shape in a cut surface (YZ plane). Further, the intersection of the concave cross-sectional shape of the groove and the line symmetry axis is defined as the bottom of the groove, and one plane perpendicular to the line symmetry axis is defined as the reference plane 102 for all grooves.

As shown in FIG. 1B, the distance from the bottom of each groove to the reference surface 102 in the XZ plane is a random shape, so that “all adjacent surfaces in any cut surface perpendicular to the longitudinal direction of the groove are adjacent to each other. It is possible to obtain a shape in which θ _{1 of the} intersection points are different and θ _{2 of} all adjacent intersection points are different.

In addition, as shown in FIG. 1C, the distance between the line connecting the bottom of the groove in the YZ plane and the reference plane 102 is changed into a shape that changes in the Y direction, so that “in any adjacent groove, As the cutting plane perpendicular to the longitudinal direction of the groove moves along the longitudinal direction of the groove, the shape of the intersections θ ₁ and θ ₂ is fluctuating ”.

The distance from the bottom of each groove in the XZ plane to the reference plane 102 is random, but the angle between the line connecting the bottom of the groove in the YZ plane and the reference plane 102 has a constant shape as it advances in the Y direction. Intersections with θ ₁ or θ ₂ of 25 ° or less may continue in the Y direction, and a significant decrease in material rigidity occurs at such sites, so that the intersections may fall and fluctuate. Is expensive. In addition, since it is difficult to process the intersection portion with a constant thickness in a thin and accurate manner in the Y direction, a flat portion may remain between adjacent grooves.

On the other hand, in the metal mold | die of this invention, by satisfy | filling the requirements of said i)-iii), when at least one of angle (theta) ₁ of the intersection part of adjacent groove | channels and (theta) ₂ contains an angle of 25 degrees or less. Even if it exists, since the intersection part whose angle θ ₁ or θ ₂ is 25 ° or less does not continue in the Y direction, the intersection part does not fall down or fluctuate. Moreover, since it is not necessary to make the thickness of the intersection part constant in the Y direction, it is possible to obtain a mold having no flat part between adjacent grooves.

In the present invention, it is preferable that at least one of θ ₁ and θ ₂ is in the range of 15 to 25 °. If the angle becomes too small, the rigidity of the intersection part having a concave cross section is weakened, and the life as a mold may be shortened.

In the present invention, both θ ₁ and θ ₂ are preferably 45 ° or less. If either θ ₁ or θ ₂ is an angle of 25 ° or less, and θ ₁ and θ ₂ are both 45 ° or less, the luminance unevenness of the imprint molded product formed with the mold of the present invention is reduced. This is because it can be solved more effectively.

In the present invention, as shown in FIG. 3, for every other groove, the distance from the bottom of each groove to the reference plane 102 in the XZ plane is constant, and the line connecting the bottom of the groove in the YZ plane and the reference plane It is preferable that the shape be constant as the distance from 102 advances in the Y direction. In other words, satisfying such a requirement means that as shown in FIGS.
Group A) a groove whose distance from the bottom of each groove in the XZ plane to the reference plane 102 is constant, and whose distance between the line connecting the bottom of the groove in the YZ plane and the reference plane 102 is constant as it advances in the Y direction. Set B group) The distance between the bottom of each groove on the XZ plane and the reference plane 102 is random, and the distance between the line connecting the bottom of the groove on the YZ plane and the reference plane 102 changes in the Y direction. As a set, the grooves constituting the A group and the grooves constituting the B group are molds alternately arranged in parallel. All the grooves are “the distance from the bottom of each groove in the XZ plane to the reference plane 102 is random, and the distance between the line connecting the bottom of the grooves in the YZ plane and the reference plane 102 changes as the Y direction proceeds.” If it is, it is difficult to accurately grasp and calculate the activation of the groove, and it is very difficult to adjust parameters such as pitch and height. However, since the grooves constituting the A group are alternately sandwiched between the grooves constituting the B group as described above, the trajectories of both can be accurately grasped and calculated. Parameters can be adjusted more arbitrarily. Moreover, the cross-sectional concave shape of the groove | channel which comprises the said A group and the cross-sectional concave shape of the groove | channel which comprises B group may not be the same.

  In the present invention, it is preferable that the distance between the line connecting the bottoms of the grooves on the YZ plane and the reference plane changes periodically as the distance advances in the Y direction. The period is preferably 20 mm to 200 mm, more preferably 30 mm to 50 mm. If the period is less than 20 mm, improvement of the luminance unevenness problem may be insufficient. If the cycle exceeds 200 mm, the improvement of the collapse and fluctuation of the intersection of adjacent grooves may be insufficient. In addition, it is preferable that the line which connects this bottom part draws a continuous curve. By making it periodic, it can be considered that the average pattern shape matches the design value, and it can be handled as equivalent to a combination of simple pattern shapes. In other words, when changing irregularly instead of periodically, there is a possibility that a portion where only shallow grooves or deep grooves gather in the surface of the mold. This is because the periodic and shallow grooves are uniformly dispersed in the mold surface. In the present invention, it is preferable that there is a random shift in the phase of this period between adjacent grooves. The resolution of the shift amount is preferably not more than the pitch of the concave cross section, that is, not more than 1 mm, more preferably not more than 200 μm. More preferably, it is 1 nm-1 micrometer, and it is so preferable that it is small. NC machining data using a random function is often used for machining with shifted phases.

In the present invention, the average aspect ratio of the concave cross-section is preferably 1 to 3. The "aspect ratio", as shown in FIG. 4, the sum of the distances w ₂ from the distance w ₁ and the bottom 6 of the concave cross-sectional profile of the intersection 1 in the X direction to the bottom 6 to the intersection 2, Z is the ratio of the sum of the distance _{h 2} from the distance _{h 1} and the bottom 6 from the intersection 1 in the direction to the bottom 6 to the intersection 2 _{is (h 1 + h 2) /} (w 1 + w 2). The “average aspect ratio” ideally refers to the average value of the aspect ratios of all the concave cross sections in all the XZ planes, but here, 10 points in 10 XZ planes selected at random are selected. The arithmetic average value of the aspect ratios of the concave sectional shapes, that is, the arithmetic average of the aspect ratios of the concave concave shapes of 100. By setting the average aspect ratio to 1 or more, when an imprint molded product of an optical film is formed using the mold of the present invention, light incident obliquely from the fluorescent tube is more reliably directed to the front direction. And uneven brightness can be more reliably prevented. On the other hand, by setting the aspect ratio to 3 or less, it is possible to secure luminance when the screen is viewed obliquely. A more preferable range of the aspect ratio is 1.5 to 2.8.

  A method for manufacturing the imprint mold shown in FIGS. 1 and 3 will be described. First, using a cutting tool with the same shape as the desired cross-sectional shape on the shaping surface side of the mold material, which will be described later, the cross-sectional concave shape is cut by an ultra-precision machine capable of three-dimensional processing. Can be added to the shaping surface. Various types of ultra-precision processing machines are known, such as a planar (shaper) method, a fly-cut method, an end mill method, and a lathe processing method. In the present invention, among them, a planar (shaper) method for shaping a concave shape by moving a working bite or a die straight along a shaping surface side of a mold material, which is considered to be the highest accuracy, and It is possible to use a fly-cut method in which a machining tool is rotationally driven and a tool or a die is moved in a direction perpendicular to the rotation axis direction to form a concave cross section. In the planar (shaper) method, the cutting tool is moved straight along the mold to shape the concave shape of the cross section, so that continuous and efficient processing is possible, but there are burrs and burrs on the edge of the concave shape of the cross section. It is relatively easy to generate. In addition, the fly-cut method can process burrs and burrs relatively less than the planar (shaper) method, but it has the disadvantage that it takes a lot of processing time. Is preferred.

Examples of the material of the machining tool include carbon tool steel, cemented carbide, ceramics, diamond, cubic boron nitride, etc., but it has a highly accurate cross-sectional concave shape of nanometer level due to its crystal hardness and high thermal conductivity. More preferred are diamonds obtained over distance. In addition, by using diamond, more preferably single crystal diamond, the surface roughness of the cutting surface can be processed to be extremely small, so that desired optical characteristics can be easily obtained. Therefore, it is very preferable in the field used in the present technology. Single crystal diamond is used. However, while a very clean processed surface can be formed, if there are any defects such as burrs or scratches, there may be a problem that the portion becomes very conspicuous. In that case, for example, Document 3 and the like have proposed a process in which fluctuations are given without making the intersecting line part of the cross-sectional concave shapes of adjacent grooves straight. In this case, the technique that does not make the defect conspicuous has some common features, but because it aims to improve the brightness, it has a triangular pattern with an angle of about 45 °, and the cross-sectional concave shape of the adjacent groove Although the intersection line fluctuates, the angle of the intersection point does not change and is constant at an angle of about 45 °. Therefore, in the present invention, the angle θ ₁ and θ ₂ between the line parallel to the line symmetry axis and the tangent at the intersection of adjacent grooves in the cross-section of adjacent grooves is processed to be an intersection at a portion including an angle of 25 ° or less. This is very different from the technology that enables stable cutting without falling and fluctuations.

  Any imprint mold material may be used as long as it can obtain the desired press strength, pattern processing accuracy, and releasability of the imprint molded product. For example, a metal material containing stainless steel, nickel, copper, etc., silicone Glass, ceramics, resins, or those whose surfaces are coated with an organic film for improving releasability are preferably used. The concave cross-sectional shape of the imprint mold is formed corresponding to the fine concave-convex shape to be imparted to the surface of the imprint molded product.

  Next, a method for producing the imprint molded product of the present invention will be described. The imprint molded product of the present invention can be obtained, for example, by imparting the above uneven shape to the surface of a known thermoplastic resin film, sheet-like material, plate-like material (hereinafter referred to as a base substrate), and the like. It is done. Here, the method for imparting the uneven shape as described above is not particularly limited, and examples thereof include a thermal imprint method and an optical imprint method. Thermal imprinting is a process of heating a mold having a fine concave cross section and resin, pressing the mold against the resin, cooling, and then releasing the mold to transfer the concave cross section applied to the mold surface to the resin. It is a technique to make it. Here, the resin used for thermal imprinting may be a thermoplastic resin or a thermosetting resin, but is preferably a highly transparent resin.

  Examples of the thermoplastic resin include polyester terephthalate, polyethylene-2.6-naphthalate, polypropylene phthalate, polybutylene terephthalate, cyclohexanedimethanol copolymer polyester resin, isophthalic acid copolymer polyester resin, and spiroglycol copolymer polyester. Examples thereof include resins and fluorene copolymer polyester resins. Examples of the olefin resin include alicyclic olefin copolymer resins, and examples of the acrylic resin include polymethyl methacrylate. Further, as other resins, polycarbonate, polystyrene, polyamide, polyether, polyesteramide, polyetherester, polyvinyl chloride, and the like can be given. Furthermore, it is a copolymer which uses these as a component, and the mixture of these resin can also be used. Among them, in terms of mechanical strength, heat resistance, and dimensional stability, a biaxially stretched polyethylene terephthalate, polyethylene-2.6-naphthalate, a copolymer with other components based on these, a mixture, etc. A polyester resin is more preferably used. Examples of the thermosetting resin include acrylic resin, epoxy resin, unsaturated polyester resin, phenol resin, urea / melamine resin, polyurethane resin, silicone resin, and the like. A mixture of the above can be used.

  The base substrate applied to the present invention may be a sheet made of the above-mentioned resin alone or a laminate made of a plurality of resin layers. In this case, compared with a single sheet, surface characteristics such as slipperiness and friction resistance, mechanical strength, and heat resistance can be imparted. Thus, when it is a laminate composed of a plurality of resin layers, it is preferable that the entire sheet satisfies the above-mentioned requirements, but even if the entire sheet does not satisfy the above-mentioned requirements, there is a layer that satisfies at least the above-mentioned requirements. If it is formed on the surface layer, the surface can be easily formed.

  On the other hand, the photoimprint method is a method of applying a photocurable resin on a base substrate, pressing a mold having a fine concave cross section against the photocurable resin portion, and pressing the mold In this method, the photocurable resin is cured by irradiating ultraviolet light from the opposite direction, and the mold is released to transfer the concave sectional shape of the mold to the base substrate. However, when the material of the mold is transparent such as glass, the opposite direction is not necessary.

  Examples of the photocurable resin include a compound having at least one radical polymerizability in the molecule or a compound having cationic polymerizability. The compound having radical polymerizability is a compound that undergoes a polymer or a crosslinking reaction by irradiation with active energy rays in the presence of a polymerization initiator that generates radicals by active energy rays. For example, the structural unit includes at least one ethylenically unsaturated bond, and includes other functional vinyl monomers in addition to a monofunctional vinyl monomer. Moreover, these oligomers, polymers, and mixtures may be used. Examples of the compound having at least one cationic polymerizability in the molecule include one or more compounds selected from a compound having an oxirane ring, a compound having an oxetane ring, and a vinyl ether compound.

  As the base substrate, in the case of a film, for example, a polyethylene terephthalate that has been vacuum-dried at 180 ° C. for 4 hours is supplied to a film forming apparatus consisting of a main extruder, melt-extruded, and this sheet is a mirror-cooled drum having a surface temperature of 20 ° C. Cast above to obtain an unstretched sheet. Then, this sheet can be obtained by stretching 3 times in the longitudinal direction at 85 ° C. and continuously stretching 3 times in the width direction in an atmosphere at 100 ° C. In addition, when the base substrate is a sheet or plate, the thickness may be different from that of the film, which may not be obtained by the same manufacturing method, but may be manufactured by a known method.

  The imprint molded article of the present invention as described above is useful because it can be suitably used for the light emitting surface of a backlight (surface light source), and can exhibit good performance particularly in a direct type backlight.

  The direct type backlight has, for example, a light emitting means such as a cold cathode ray tube in a hollow casing, and an imprint molded product is disposed above the light emitting means. The light emitted from the light emitting means is transmitted to the casing. This is a surface light source that emits light from one main plane of the body, that is, a surface on which an imprint molded product is disposed. In addition, a so-called reflecting plate exhibiting excellent reflection characteristics may be mounted on the bottom and side portions of the hollow casing in the direct type backlight. The reflective plate may be a single reflective film, or may be a housing or a laminate of the reflective film on an aluminum plate different from the housing. Further, it may be grooved according to the arrangement of the light sources. The number of light emitting means such as cold cathode ray tubes and the size of the screen are not particularly limited.

  When the imprint molded product of the present invention is applied to such a surface light source, the surface light source has high brightness without increasing unevenness in brightness, and can be made thin and light. It is possible to improve the dimensional stability and strength. Therefore, it is suitably used particularly for a direct type backlight of a liquid crystal display. In addition, when applying the imprint molded product of this invention to a surface light source, it arrange | positions so that the surface of the side which has the above-mentioned uneven | corrugated shape of a characteristic shape may be on the opposite side to a light source.

  Further, in the surface light source, the imprint molded product of the present invention may be disposed alone on the light emitting means, but a bead layer-containing base material or a hemispherical dome shape is provided on the surface on the light emitting means. By disposing the substrate and placing the imprint molded product of the present invention thereon, good luminance characteristics can be obtained not only when viewed from the front but also when the display is viewed obliquely. The bead layer-containing base material refers to a layer in which transparent beads are coated on a transparent base material or a diffusion base material containing a diffusing material therein and fixed with a binder resin. Further, the base material having a hemispherical dome shape on the surface refers to a surface of a diffusion base material in which a transparent base material or a diffusing material is contained, and a hemispherical dome shape is provided by pressing or the like. .

Hereinafter, the present invention will be described in more detail based on examples. In the following Examples and Comparative Examples, a size of □ 80 mm (excluding Example 9 and Comparative Example 3), a thickness of 20 mm, and a surface material of nickel-phosphorus were used. In addition, a shaper method was used as a processing method, and cutting was performed at a cutting speed of 10 m / min.
The imprint molded product was pressed at a heating temperature of 130 ° C. to 20 ° C. after pressing the mold shown in each example and comparative example on a base substrate made of copolymer polyethylene terephthalate having a three-layer structure with a thickness of 120 μm. By cooling, the concave shape of the cross section of the mold was obtained by transfer molding.

  Evaluation items and methods for molds and imprint molded products are shown below.

  (1) Appearance defect: It refers to a point-like or line-like defect that can be visually confirmed and seen aperiodically. It is often caused by burrs that occur during processing, or by falling or fluctuating the intersections of adjacent stripe pattern shapes due to defective cutting.

  (2) Appearance striped pattern: It refers to a dot-like or linear defect that can be visually confirmed and seen periodically. This is often caused by a phase shift or machining characteristics or machining phenomenon of an NC machine.

  (3) Colored: A non-periodic or periodic color unevenness defect that can be visually confirmed.

  (4) Moire: Interference fringes that are visually generated when a plurality of films having a concavo-convex shape are superimposed.

  As an evaluation method of the above (1) to (4), three people visually check the imprint mold and the shaped surface of the molded product, and when all the members recognize the defect as defective, x three people A four-step evaluation is performed, where △ is the case of two people, ◯ is the case of only one, and ◎ is the case where no one is able to recognize.

(5) Luminance unevenness: A diffusion plate (made of acrylic having a thickness of 2 mm) set on the cold cathode ray tube 7 (FIG. 6) is removed from the direct type backlight described in Japanese Patent Laid-Open No. 5-119111. Instead of the diffuser plate, the imprint molded product 8 of the present invention is formed so that the surface having the irregularities is on the CCD camera side, and the direction perpendicular to the XZ plane of the substrate and the longitudinal direction of the cold cathode ray tube Install to match. After stabilizing the light source by lighting the cold cathode ray tube for 60 minutes, using EYESCALE-3 (Eye System Co., Ltd.), attach the attached CCD camera to the backlight surface at a point 90 cm from the backlight surface. It is installed so as to be in front, and the luminance (cd / m ² ) is measured. At this time, the distance a between the cold cathode ray tube and the imprint molded product 8 is 10 mm, and the distance b between adjacent cold cathode ray tubes is 20 mm. Further, when the intersection of the middle line drawn between adjacent cold cathode ray tubes and the imprint molded product 8 is c, a line connecting c and the cold cathode ray tube, and from the cold cathode ray tube to the imprint molded product 8 The angle α formed with the drawn perpendicular is 45 degrees.

Note that the luminance is the position of the two cold cathode ray tubes in the center of the backlight (two points in total), and the position of the midpoint of the two cold cathode ray tubes and two further cold cathode ray tubes adjacent thereto. Observe at (total 3 points), and let L _{max be} the average luminance at the positions of the cold cathode ray tubes and L _min be the average luminance at the midpoint positions of the four cold cathode ray tubes. At this time, the positions of the two cold cathode tubes and the two further cold cathode ray tubes adjacent thereto are determined by measuring the luminance only with the backlight without installing the light diffusion base material.

(L _max −L _min ) is used as a value indicating luminance unevenness. The smaller the brightness unevenness, the better. When the luminance unevenness is 400 cd / m ² or less, ◎, when 400 cd / m ² is exceeded and 600 cd / m ² or less, ○, and when 600 cd / m ² is exceeded, ×.

For the molds of the following examples and comparative examples, the A group and the B group are defined as follows as the groove shape.
Group A) A set of grooves in which the distance from the bottom of each groove in the XZ plane to the reference plane is constant, and the distance between the line connecting the bottom of the groove in the YZ plane and the reference plane is constant as the Y direction proceeds.
B group) The distance between the bottom of each groove on the XZ plane and the reference plane is random, and the distance between the line connecting the bottom of the groove on the YZ plane and the reference plane periodically changes in the Y direction. set.
However, the X direction is a direction perpendicular to the longitudinal direction of the groove and the line symmetry axis, the Y direction is the longitudinal direction of the groove, and the Z direction is a direction parallel to the line symmetry axis. The XZ plane is a cutting plane perpendicular to the longitudinal direction of the groove, and the YZ plane is a cutting plane parallel to the longitudinal direction of the groove and including an axis of line symmetry.

[Example 1]
(1) Concave cross-section: one of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.0250 ² + Y ² /0.0625 ² = 1) A group which is a part of. The other group is a group B whose concave section is a part of a semicircular shape (25 μmR).
(2) Pitch: 39.75 μm
(3) Height: Group A: 27.7 μm
Group B: Randomly changes within a range of 9 to 27.7 μm.
(4) Period of group B: 20 mm, and the phase of adjacent grooves in group B is shifted by 1.25 mm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 16 ° to 41 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were colored and moire, but at a level with no problem. Further, although the appearance stripe pattern due to the phase shift periodically appeared, there was no actual harm that the appearance stripe pattern appeared as unevenness of the backlight of the liquid crystal display screen in the LCD backlight of the present invention.

[Example 2]
(1) Concave cross-section: one set of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.050 ² = 1) A group which is a part of. The other group is a group B in which the concave cross-section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.050 ² = 1). For Example 1, two sets of grooves were both elliptical.
(2) Pitch: 34.25 μm
(3) Height: Group A: 23.7 μm
Group B: Randomly changes within a range of 7.3 to 23.7 μm.
(4) Period of group B: 20 mm, and the phase of adjacent grooves in group B is shifted by 1.25 mm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 19 ° to 41 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were colored and moire, but at a level with no problem. Further, although the appearance stripe pattern due to the phase shift periodically appeared, there was no actual harm that the appearance stripe pattern appeared as unevenness of the backlight of the liquid crystal display screen in the LCD backlight of the present invention.

[Example 3]
(1) Concave cross-section: one set of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.050 ² = 1) A group which is a part of. The other group is a group B in which the concave cross-section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.050 ² = 1). Compared to Example 2, the method of shifting the phase of adjacent grooves in Group B was made random.
(2) Pitch: 34.25 μm
(3) Height: Group A: 23.7 μm
Group B: Randomly changes within a range of 7.3 to 23.7 μm.
(4) Period of group B: 20 mm, and the phase of adjacent grooves in group B is irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 19 ° to 41 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were slightly colored and moire, but had no appearance defect and achieved low luminance unevenness. Compared to Example 2, a slight improvement in the appearance stripe pattern was observed by randomizing the phase shift of the period.

[Example 4]
(1) Concave cross-section: one set of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.050 ² = 1) A group which is a part of. The other group is a group B in which the concave cross-section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.050 ² = 1). Compared to Example 2, the period of Group B was 6 mm.
(2) Pitch: 34.25 μm
(3) Height: Group A: 23.7 μm
Group B: Randomly changes within a range of 7.3 to 23.7 μm.
(4) Period of group B: 6 mm, and the phase of adjacent grooves in group B is irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 19 ° to 41 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained had no appearance defects, although the appearance stripe pattern, coloring and moire were seen thinly. However, the luminance unevenness was slightly larger as compared with Example 3 having a rocking period of 20 mm.

[Example 5]
(1) Recessed cross section: all grooves are a group B in which the recessed cross section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.0625 ² = 1).
(2) Pitch: 40.52 μm
(3) Height: It changes at random within the range of 15-27 micrometers.
(4) Period: 20 mm, the phases of adjacent grooves are irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 16 ° to 28 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained had thin appearance defects and coloring, but had no appearance stripes and moire and achieved low luminance unevenness.

[Example 6]
(1) Concave cross-section: one set of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.050 ² = 1) A group which is a part of. The other group is a group B in which the concave cross-section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.050 ² = 1). With respect to Examples 2 to 4, the angles of θ ₁ and θ ₂ were made smaller by reducing the pitch.
(2) Pitch: 38.75 μm
(3) Height: Group A: 23.7 μm
Group B: Randomly changes within the range of 14.3 to 23.7 μm.
(4) Period of group B: 60 mm, the phase of adjacent grooves in group B is irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 17 ° to 27 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were lightly colored, but had no appearance defects, striped pattern and moire, and achieved low luminance unevenness.

[Example 7]
(1) Concave cross-section: one set of two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.050 ² = 1) A group which is a part of. The other group is a group B in which the concave cross-section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.050 ² = 1). For Example 6, the period of group B was 40 mm.
(2) Pitch: 38.75 μm
(3) Height: Group A: 23.7 μm
Group B: Randomly changes within the range of 14.3 to 23.7 μm.
(4) Period of group B: 40 mm, and the phase of adjacent grooves in group B is irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 17 ° to 27 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were lightly colored, but had no appearance defects, striped pattern and moire, and achieved low luminance unevenness.

[Example 8]
(1) Concave cross-section: one of the two sets of grooves collected every other groove is elliptical in cross-section (X ² /0.025 ² + Y ² /0.0625 ² = 1) A group which is a part of. The other group is a group B in which the concave cross section is a part of an elliptical shape (X ² /0.025 ² + Y ² /0.0625 ² = 1). For Examples 2 to 4, 6, and 7, the elliptical shape was changed to a higher aspect.
(2) Pitch: 37.25 μm
(3) Height: Group A: 27.7 μm
Group B: Randomly changes within the range of 15.5 to 27.7 μm.
(4) Period of group B: 40 mm, and the phase of adjacent grooves in group B is irregularly shifted with a random function with an accuracy of 1 nm.
(5) θ ₁ , θ ₂ : θ ₁ and θ ₂ are in the range of 15 ° to 26 °, and one of θ ₁ or θ ₂ is 25 ° or less.
As shown in Table 1, the mold and the imprint molded product thus obtained were lightly colored, but had no appearance defects, striped pattern and moire, and achieved low luminance unevenness.

[Example 9]
(1) Recessed cross section: Same as Example 8.
(2) Pitch: Same as in Example 8.
(3) Height: Same as in Example 8.
(4) Period: Same as Example 8.
(5) θ ₁ , θ ₂ : Same as in Example 8.
(6) Size: 32-inch screen compatible (900mm x 500mm)
As shown in Table 1, the mold and the imprint molded product thus obtained had only a light color even in a large area as in Example 8, and there were no appearance defects, stripes, and moire. The luminance unevenness was also very good.

[Comparative Example 1]
(1) Cross section concave shape: Group A in which all the grooves are part of an elliptical cross section concave shape (X ² /0.025 ² + Y ² /0.0625 ² = 1).
(2) Pitch: 41.5 μm
(3) Height: 27.7 μm
(4) θ ₁ , θ ₂ : θ ₁ and θ ₂ are 15 °
In the mold thus obtained, θ ₁ and θ ₂ satisfy 25 ° or less, but are all constant. Therefore, as shown in FIG. 7 (b), many burrs and ridge lines remain and fall over the entire surface. The shape as designed as shown in FIG. 7A was not obtained. Even if the cutting conditions were changed, such as changing the cutting speed within a range of 1 to 40 m / min, almost no improvement was observed.

[Comparative Example 2]
(1) Cross section concave shape: Group A in which all the grooves are part of the elliptical cross section (X ² /0.025 ² + Y ² /0.050 ² = 1).
(2) Pitch: 35.0 μm
(3) Height: 14.3 μm
(4) θ ₁ , θ ₂ : θ ₁ and θ ₂ are 27 °
As shown in Table 1, the mold and the imprint molded product thus obtained were uniform over the entire surface without any appearance defects or appearance stripes. However, since θ ₁ and θ ₂ exceeded 25 °, coloring, moire, and luminance unevenness were both bad.

[Comparative Example 3]
(1) Concave cross section: Same as Comparative Example 2.
(2) Pitch: Same as Comparative Example 2.
(3) Height: Same as Comparative Example 2.
(4) θ ₁ , θ ₂ : Same as Comparative Example 2.
(5) Size: 32-inch screen compatible (900mm x 500mm)
As shown in Table 1, although the mold and the imprint molded product thus obtained had the same concavo-convex shape as Comparative Example 2, some appearance defects occurred due to the large area. Regarding coloring, moire, and luminance unevenness, all were bad as in Comparative Example 2.

FIG. 1 (a) shows a model of a mold according to an embodiment of the present invention in which grooves in which the distance from the reference plane to the bottom is randomly distributed in both the X direction and the Y direction are arranged. FIG. FIG.1 (b) is the schematic which showed the X direction cross section of Fig.1 (a). FIG.1 (c) is the schematic which showed the Y direction cross section of the groove | channel with Fig.1 (a) (AA sectional arrow directional view of FIG.1 (b)). FIG. 2 is a schematic view showing an angle between adjacent concave shapes in one embodiment of the mold according to the present invention. FIG. 3A shows a groove A in which the distance from the reference surface to the bottom is substantially the same in both the X and Y directions, and the distance from the reference surface to the bottom is X in one embodiment of the mold according to the present invention. FIG. 5 is a schematic diagram schematically illustrating a mold in which grooves B whose directions are randomly distributed and whose Y direction is periodically varied are alternately arranged in parallel. FIG. 3B is a schematic view showing a cross section in the X direction of FIG. FIG.3 (c) is the schematic which showed the Y direction cross section of the groove | channel A with Fig.3 (a) (AA cross-sectional arrow line view of FIG.3 (b)). FIG. 3D is a schematic view showing a Y-direction cross section of a certain groove B (a cross-sectional view taken along the line BB in FIG. 3B). FIG. 4 is a schematic view showing an aspect ratio of a concave cross section in one embodiment of the mold according to the present invention. FIG. 5 is a schematic view showing a pitch of a concave section in one embodiment of the mold according to the present invention. FIG. 6 is an explanatory diagram of a luminance unevenness measuring method. Fig.7 (a) is the schematic which showed the design concave shape of a certain metal mold | die. FIG. 7B is a schematic view showing the actual processing concave shape of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Schematic diagram of mold showing one embodiment of the present invention 101: Cross section concave shape showing one embodiment of the present invention 1, 2: Intersection portion of adjacent cross section concave shape 3: Axisymmetric axis passing through the intersection portion 1 Line 4: parallel to tangent 5 at intersection 1 of concave section in one section: tangent 6 at intersection 1 of concave section in the other section 6: bottom 10 of concave section of cross section: axis of symmetry of concave section h ₁ : cross section Z-direction distance h ₂ from the intersection portion 1 to the bottom portion 6 of the concave shape: Z-direction distance w ₁ from the intersection portion 2 to the bottom portion 6 of the concave section in the X direction: X-direction distance from the intersection portion 1 to the bottom portion 6 of the concave section w ₂ : X-direction distance P from the intersection 2 of the concave cross section to the bottom 6 P: X-direction distance from the bottom of a certain cross-sectional uneven shape to the bottom of the next concave cross-section a: Cold cathode ray tube and imprint molded product Distance b: Distance between adjacent cold cathode ray tubes c: Between adjacent cold cathode ray tubes Intersection of the midline and the imprint molded article had alpha: angle between the line connecting the c and the cold cathode ray tube, a vertical line drawn from the cold cathode ray tube imprint moldings

Claims (10)

A mold in which a shape in which a plurality of straight grooves are arranged in parallel with each other is formed on the surface,
The concave shape of the cross section at the cutting plane perpendicular to the longitudinal direction of each groove is a part of a line-symmetrical curve, and the curve forms a tangent at a point on the curve and a line parallel to the line-symmetrical axis as it moves away from the line-symmetrical axis. It is a curve where the acute angle gradually decreases,
The line symmetry axes of the concave sections are parallel,
The intersection of adjacent concave grooves is defined as the intersection, and the acute angle between the tangent at the intersection of one of the grooves and the straight line parallel to the axis of symmetry is θ ₁ , and the intersection of the other concave When an acute angle formed by a tangent line at the portion and a straight line parallel to the axis of line symmetry is θ ₂ ,
In the arbitrary cut surface, at least one of θ ₁ and θ ₂ at all the intersections is 25 ° or less,
In any cut surface, θ ₁ of all adjacent intersections are different, and θ _{2 of} all adjacent intersections are different,
In the arbitrary adjacent groove, the mold in which θ ₁ and θ _{2 at the} intersections change as the cut surface moves along the longitudinal direction of the groove. _2. The mold according to claim 1, wherein at least one of θ ₁ and θ ₂ at all the intersections is 15 to 25 ° in the arbitrary cut surface. 3. The mold according to claim _1, wherein θ ₁ and θ ₂ of all intersections are 45 ° or less on the arbitrary cut surface. When the intersection of the concave cross section of each groove and the line symmetry axis is the bottom of the groove, and one plane perpendicular to the line symmetry axis is a reference plane for all grooves,
The mold according to any one of claims 1 to 3, wherein a line connecting a bottom portion in a plane parallel to the longitudinal direction of an arbitrary groove and including an axis of line symmetry is a line whose distance from the reference plane changes periodically. . When the intersection of the concave cross section of each groove and the line symmetry axis is the bottom of the groove, and one plane perpendicular to the line symmetry axis is a reference plane for all grooves,
All the grooves that constitute one set of the set of two sets of grooves that are collected every other groove satisfy the following (1) (2). Mold.
(1) In the arbitrary cut surfaces, the distances from the bottoms of all the grooves constituting one set to the reference surface are the same.
(2) For all the grooves constituting one set, the line connecting the bottoms in the plane parallel to the longitudinal direction of the grooves and including the axis of line symmetry is parallel to the reference plane.   For all the grooves constituting the other set of the two sets, each of which is collected every other groove, a line connecting the bottoms in a plane parallel to the longitudinal direction of the grooves and including the line symmetry axis is The mold according to claim 5, wherein the mold is a line whose distance to the reference surface changes periodically.   The mold according to claim 4 or 6, wherein a period of the periodically changing line is 20 to 200 mm.   The mold according to any one of claims 1 to 7, wherein an average aspect ratio of the concave cross section is 1 to 3.   The imprint molded product formed using the metal mold | die in any one of Claims 1-8.   A surface light source comprising the imprint molded article according to claim 9 and a light emitting means.

Images