KR20110053466A - Method for producing optical sheet, optical sheet, and light source unit including optical sheet, display unit - Google Patents

Abstract

Conventionally, fine surface molding cannot be accurately reproduced by a solution for adjusting the resin temperature of the thermoplastic resin in extrusion molding or a method for adjusting the circumferential speed of the roll during extrusion molding. It was impossible to sufficiently achieve the performance of the surface molding designed for the purpose, and it was impossible to develop the optical sheet using the same, the light source unit using the optical sheet, and the display device. According to the present invention, in the method for producing an optical sheet which is surface-molded by using a molding roll subjected to surface processing for transferring an uneven shape, the peripheral speed of the molding roll is set to Va, and the peripheral speed Vb of the take-up roll (B) is obtained. In this case, the circumferential speed Vb is a circumferential speed of 103 to 120% of the circumferential speed Va. Moreover, the optical sheet produced by such a manufacturing method, the light source unit containing the same, and a display apparatus are also included in this invention.

Description

A manufacturing method of an optical sheet, an optical sheet, and a light source unit and a display device including the optical sheet {METHOD FOR PRODUCING OPTICAL SHEET, OPTICAL SHEET, AND LIGHT SOURCE UNIT INCLUDING OPTICAL SHEET, DISPLAY UNIT}

The present invention relates to a method for producing an optical sheet having a precise surface shape for exhibiting functionality. The present invention also relates to an optical sheet in which a precise surface shape manufactured by the manufacturing method significantly affects its performance, a light source unit including the optical sheet, and a display device.

Thermoplastic resins are widely used in materials such as wood, metal, glass and the like from the viewpoints of heat resistance, impact resistance, weight, ease of processing and the like. In particular, sheet materials are widely used as roofing materials, exterior materials such as exterior wall materials, interior materials such as top plates and inner wall materials, and outdoor signboards, which have conventionally been used with wood and metal. Above all, since the transparent thermoplastic resin is excellent in heat resistance, impact resistance and transparency, the sheet material is an optical material that replaces glass, and is used for building materials such as window materials, impact-resistant transparent materials for automobile windows, and large tanks in aquariums. Widely used in pressure resistant transparent materials.

The surface shape of such a thermoplastic resin sheet is not only glossy and smooth, but also embossed with fine concavo-convex, and those having two-dimensional and three-dimensional regular concave-convex shapes. It is common to mold continuously using a transfer roll.

These surface shapes are melted into a metal embossed roll formed in a shape in which the original circumferential performance is sufficiently exhibited on the outer circumferential surface and a shape in which the unevenness is inverted, and the thermoplastic resin sheet in the softened state is introduced to the sheet. It is molded by transferring. The following patent document is mentioned as an example of a specific indication.

Patent Document 1 discloses a method for producing an optical sheet that is free from appearance defects such as wave shape, thickness unevenness, and wrinkles as a whole by adjusting the temperature of the extruded thermoplastic resin.

Patent Document 2 discloses that it is possible to mold precise irregularities by adjusting the temperature of the die or the resin temperature immediately before the surface molding in the method for producing a surface molding resin sheet which is surface-molded at least on one side by extrusion molding. .

In Patent Document 3, in the method for producing a polycarbonate resin sheet surface-molded at least both sides by extrusion molding, by controlling the temperature of the die and the temperature of each cooling roll, the surface molding can be efficiently transferred to both sides. Is disclosed.

In addition, Patent Document 4 discloses a method for producing a thermoplastic resin sheet to which surface molding using a plurality of rolls is not applied, wherein the thickness variation and retardation are adjusted by adjusting the peripheral speeds of the second and third rolls. It is disclosed that the variation is small and an optically suitable sheet is obtained.

In patent document 5, the thermoplastic resin after discharge from a die is provided upstream of the circumferential speed of the 2nd roll (die roll) adjacent to a 1st roll (nip roll), and the 3rd roll (peel roll) which keeps contacting. By adjusting the circumferential speed of a roll (draw roll), surface molding can be performed efficiently, the curvature of the whole sheet is eliminated, and it is disclosed that the optically suitable sheet is obtained.

Patent Document 6 describes that the thermoplastic resin after discharge from the die adjusts the circumferential speed of the first roll (mirror roll) and the circumferential speed of the second roll (marking roll) to be in continuous contact with the mirror, and further mirrors the third roll. It is disclosed that fine surface molding can be efficiently performed by setting a roll.

Japanese Laid-Open Patent Publication 2003-245966 JP H10-180846 JP H06-190917 Japanese Unexamined Patent Publication No. 2003-236914 Japanese Unexamined Patent Publication No. 2007-216481 Japanese Laid-Open Patent Publication No. 2006-130901

However, the optical sheet having a surface molding (for example, an optical element having a pitch of 200 mu or less of high molding rate and high thickness precision) that achieves high optical performance used in a member of a flat panel display such as a liquid crystal type in recent years. Continuous production by an extruder is a solution speed for adjusting the resin temperature of the thermoplastic resin in the extrusion molding described in Patent Documents 1 to 3, and the circumferential speed of the roll during extrusion molding in the contents described in Patent Documents 4 and 5 It is impossible to achieve by adjusting the Moreover, even if it combines these indications simply, it is impossible to obtain the resin sheet of the high molding rate and high thickness precision stably in the process, and the optical sheet using it and the direct type using the optical sheet are It was not possible to develop a light source unit and a display device.

This invention is made | formed in view of such a situation, Comprising: It aims at providing the manufacturing method of the optical sheet which has the surface shape which solves the problem of said prior art, and fully exhibits original design performance. Moreover, it aims at providing the optical sheet manufactured by such a manufacturing method, the light source unit using this optical sheet, and a display apparatus.

In the first embodiment for achieving the above object, the present invention provides a method for producing an optical sheet, which is surface molded by using a molding roll surface-processed so that the optical element is molded on the sheet, and the peripheral speed of the molding roll is Va. When the circumferential speed of the take-up roll (draw roll) is set to Vb, the circumferential speed Vb is set to 103 to 130% of the main speed Va.

In the second embodiment, in the first embodiment, the optical element is molded almost parallel to the take-up direction, and the cross section is convex or the convex top and the cross section are concave. Or it provides the manufacturing method of the optical sheet characterized by the substantially ridge-shaped optical element arrange | positioned largely alternately substantially parallel in a concave arc shape.

In the third embodiment, in the first and second embodiments, the gap between the top and the top of the almost ridge optical element, or the gap between the valley and the valley, is 200 µm or less. To provide.

The optical sheet thus produced exhibits excellent performance especially as an optical sheet because the molding of the surface is transferred to a shape as reproducibly optically designed. In addition, the light source unit and the display device using the optical sheet also exhibit excellent performance.

The take-up direction is a traveling direction of the sheet, that is, a sheet longitudinal direction.

As described above, according to the present invention, an optical sheet capable of sufficiently exhibiting the original design performance can be efficiently produced. In addition, the optical sheet of the present invention thus produced exhibits excellent performance especially as an optical sheet because the molding of the surface is transferred as optically designed. The light source unit and the display device using the optical sheet also exhibit excellent performance.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of one example of the manufacturing process of the resin sheet by extrusion molding of this invention.
2 is an explanatory view of one example of a molding roll surface-treated so that an almost ridge-shaped optical element is molded almost parallel to the take-up direction of the sheet.
3 is an explanatory view of one example of a molding roll.
4 is an explanatory view of one example of a process for producing a resin sheet by extrusion molding of the present invention.
FIG. 5 is an explanatory diagram showing an arrangement form that the roll groups of FIGS. 1 and 4 can take.
FIG. 6 is an explanatory diagram showing an example of a form of an almost ridge lens of the present invention. FIG.
7 is an explanatory diagram showing an example of a form of the nearly ridge lens of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although the form for implementing this invention is demonstrated in detail with reference to drawings, this invention is not limited to these.

The present invention relates to a method for producing an optical sheet having at least one surface with a precise optical element (pitch 200 mu m or less) for exhibiting functionality.

The manufacturing method of the optical sheet of this invention (in this invention, a "sheet" and a "film" are used synonymously, and together it refers to the resin molded object of 0.05-5 mm in thickness. Hereinafter, it describes as a "sheet" uniformly.) Conventionally, it can apply to both of the thermoplastic resins used for sheet manufacture. Specific examples include polyethylene, polypropylene, ethylene-propylene copolymer, polystyrene, polyacrylonitrile, acrylonitrile-styrene copolymer, polyvinyl chloride, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polycarbonate And alicyclic structure-containing polymer resins. Details will be described later.

<Basic Configuration of Process and Equipment>

The manufacturing method of the optical sheet of this invention passes the sheet-like molten thermoplastic resin extruded by the extruder, and passes the gap of two rolls of a 1st roll and a 2nd roll, and obtains the rolled sheet-like molten thermoplastic resin, and the said And rolling the sheet-like molten thermoplastic resin to the second roll and then to the third and third roll in turn, and subsequently transferring the sheet-like molten thermoplastic resin to the take-up roll. A manufacturing method can be employ | adopted preferably.

As an extruder used for this invention, any of the single-axis type thing, the biaxial type thing, and the multiaxial type thing more than biaxial type can be used. In order to remove the oligomer at the time of polymerization, the low molecular compound which arises at the time of shaping | molding, oxygen, moisture, etc. which are dissolved in an extruder, it is preferable to provide a vent. And as a degree of vacuum of a vent, 500 hexopascals or less are preferable, More preferably, it is 200 hexpascals or less. In addition, it is preferable to use a gear pump in order to quantitatively discharge the melt-kneaded material from the viewpoint of the thickness precision and the molding of the almost ridge lens. In the case of multilayering for the purpose of providing a functional layer having ultraviolet absorbing ability, antistatic ability or the like on the surface, a multilayer extrusion apparatus can be used. In the multilayering, either a feed block method or a multi-manifold method can be used. Moreover, the above-mentioned extruder used for multilayer can use suitably. It is essential to use the choke bar system as the T die in order to secure stability in continuous production. Moreover, it is preferable to use a threaded bending lip or a heat bolt type bending lip from the viewpoint of thickness precision. It is also possible to use an automatic T-die with a heat-bolt bending lip fed back from an on-line thickness gauge or bank monitor.

<Roll placement>

With reference to Fig. 1 of the present invention, the arrangement of the roll of the present invention for carrying out the above embodiment will be described. 1 shows a sheet-like molten thermoplastic resin extruded from a die 1 of an extruder, through a gap between two rolls of a first roll 2 and a second roll 3, The process of obtaining, the process of externally externally conveying the said rolled sheet-like molten thermoplastic resin to the 2nd roll 3, and then to the 3rd 3rd roll 4, and the sheet-like molten-mold which were subsequently surface-molded The manufacturing method which has a pair of take-up rolls 5a and 5b for peeling and conveying a thermoplastic resin from the 3rd roll 4 is shown.

Since the first roll 2 is an important roll for determining the thickness of the sheet, a mirror roll is preferably used rather than a surface processed roll. In addition, when the thickness accuracy is insufficient under the influence of the linear pressure, a drum-type crowning roll can be used. The second roll 3 is selected from a mirror roll for producing a smooth surface, an emboss roll for transferring a mat, an emboss, and the like, and a roll for molding an optical element, if necessary. Although these can be used suitably according to the objective, especially when it aims at preventing damage to a sheet | seat and more efficient light diffusion of a backlight light, the roll of a mat and emboss pattern of arithmetic mean roughness Ra = 0.1-5 micrometers is used. It is preferable to use, and especially the embossing roll produced by the bead blasting method can be used suitably.

The third roll 4 is a molding roll (see Figs. 2 and 3) which is surface processed so that the optical element is molded into the sheet. An object of the present invention is to obtain an optical sheet having at least one surface with precise optical molding, so that the combination of only the mirror rolls and the emboss rolls of the second roll 3 and the third roll 4 is not selected. . 2 and 3 show a molding roll capable of molding an almost elliptical ridge-shaped optical element onto a sheet.

The setting position of the take-up roll may be set anywhere as long as the thermoplastic resin sheet is sufficiently cooled so as not to deform during contact with the take-up roll. The molding of the surface of the sheet may be deformed by the pressure between the two take-up rolls, or it may be set at a position where deformation of appearance defects such as warpage and wrinkles does not occur in the entire sheet. In addition, in the present invention, the take-up roll may be made of any material as long as it does not damage the uneven shape of the resin material and the slip of the roll hardly occurs. For example, a 60-90 degree material etc. can be employ | adopted as the rubber hardness prescribed | regulated by JISK6301. When the roll surface uses such a rubber-hard take-up roll, the slip of the roll hardly occurs without damaging the uneven shape of the resin material, and the sheet can be produced efficiently. The surface shape of the take-up roll may be any shape as long as it can be taken up without deforming the surface shape molded by the first, second and third rolls and without running obstacles such as slip.

Between the third roll 4 and the take-up rolls 5a and 5b, in order to smoothly peel the optical sheet molded with the optical element from the third roll 4, in the vicinity of the peeling line of the third roll 4. More preferably, the take off roll 6 is provided (see FIG. 4).

The take-off roll may or may not be capable of adjusting the circumferential speed. Preferably, the thing which can adjust a circumferential speed independently of a 1st roll, a 2nd roll, and a 3rd roll is selected. The main speed of a takeoff roll is 0.3 m / min-30 m / min normally, and the most preferable range is 0.5 m / min-20 m / min. When the take-off roll cannot adjust the circumferential speed or when the circumferential speed is not adjusted, the circumferential speed is usually set from the viewpoint of the productivity of the sheet. In the case where the circumferential speed can be adjusted, in order to increase the molding property, the circumferential speed ratio with the take-up roll is preferably set to 98 to 125%, more preferably 100 to 115%. If the circumferential speed ratio is smaller than this range, the take-off property from the third roll is deteriorated, so that waves tend to occur in the molded article, and the original purpose is lost. May occur), which is not preferable.

It is preferable that the take-off roll can be further temperature-controlled independently of the first roll, the second roll, and the third roll. The preferable range of temperature of a takeoff roll is Tg-50 degreeC-Tg + 30 degreeC, More preferably, it is Tg-30 degreeC-Tg + 10 degreeC. If the temperature is lower than this range, slip traces may occur between the take-off roll and the optical sheet, or warpage and wrinkles of the molded article may be concerned. Wave may generate | occur | produce in a molded article. Moreover, a sheet | seat adheres to a take-off roll, and plate | board thickness and surface precision may fall, and are unpreferable.

The arrangement position and conditions (pressure, interval, etc.) of the take off roll may be provided so that peeling of the sheet from the third roll and running of the sheet to the take-up roll can be performed smoothly and can be adjusted by a known method.

The form of arrangement | positioning of the 1st thru | or 3rd roll is not limited to the form of FIG. 1, For example, the form as (a)-(c) of FIG. 5 can also take.

As the spatial arrangement of the forming rolls (first to third rolls), any of a vertical arrangement, a horizontal arrangement, an inclined arrangement and a polygonal arrangement can be used. In the case of the vertical arrangement, molding can be performed from any one of the intermediate roll gap and the load roll gap.

<Roll speed>

First, the circumferential speed of the first roll is determined from the viewpoint of the discharge amount of the thermoplastic resin from the die, the running of the stable sheet through the whole process, and the productivity. The preferred range of the main speed of the first roll is 0.3 m / min to 30 m / min, and the most preferred range is 0.5 m / min to 20 m / min.

It is preferable that the circumferential speeds of the second roll and the third roll be 102 to 104% and 100 to 110% with respect to the circumferential speed of the first roll, respectively. Moreover, about the space | interval t1 of a 1st roll and a 2nd roll, and the space | interval t2 of a 2nd roll and a 3rd roll, it is preferable to set it as t1: t2 = 100: 60-100, Furthermore, it is 100: 70 It is more preferable to set it as -95. By selecting this setting, molding stability can be improved. If the relationship between t1 and t2 is smaller than this range, a second bank is likely to occur between the second roll and the third roll, streaked defects or wrinkles occur in the molded article, and the balance between plate thickness precision and transferability It may be difficult to take, and if not, increasing the pressure by the third roll may be insufficient and transfer may be insufficient, which is not preferable.

Like the first roll, the peripheral speed Va of the third roll 4 is determined from the viewpoint of the discharge amount of the thermoplastic resin from the die, the running of the stable sheet through the whole process, and the productivity, and the take-up rolls 5a and 5b. The circumferential speed of Vb is determined from the viewpoint of stable surface molding. The setting of the main speed Va and the main speed Vb is preferably set to the main speed Vb at 103 to 130% of the main speed Va, more preferably 104 to 125%, more preferably 105 to 120%. If the setting of the circumferential speeds Va and Vb is outside this range, for example, smaller than 103%, the sheet may be loosened, peeling from the third roll, etc. may be difficult, and the sheet may be wound around the roll, which may interfere with continuous productivity. This happens. Moreover, since the transfer of the optical element type formed in the roll surface becomes incomplete, the optical sheet which has the optical characteristic as designed is not obtained, and it is unpreferable. Moreover, when larger than 130%, the tension between a 3rd roll and a take-up roll becomes high, unreasonable peeling arises, resin foil adheres to a 3rd roll, and it is unpreferable since a sheet is torn from it. . In addition, deviation in the width direction occurs in the shape of the optical element type formed on the roll surface, and the optical performance of the finished sheet is not as designed, which is not preferable.

<Temperature of Roll>

When selecting the embodiment of FIG. 1, the temperature of 1st thru | or 3rd roll is adjustable, and these temperatures are selected by the thermoplastic resin used by this invention. In general, since the first to third rolls are intended to cool the thermoplastic resin while forming the sheet, the temperature of each roll is set lower than the discharge temperature of the thermoplastic resin from the die.

The discharge temperature is controlled by the temperature of the die. In the case of the present invention, the temperature setting Td of the die is preferably Tg + 100 ° C. to Tg + 150 ° C., more preferably, when the glass transition temperature of the thermoplastic resin that is the main body when molding is Tg (° C.). Preferably Tg + 110 ° C. to Tg + 130 ° C.

The temperature (T1) of the first roll is Tg-50 ° C to Tg + 20 ° C, more preferably Tg-30 ° C to Tg + 10 ° C. When the temperature of a 1st roll is lower than this range, since the moldability of the lens shape in a 3rd roll worsens, it is unpreferable. Moreover, it is unpreferable because there exists a possibility that driving | running | breaking obstacles, such as a wave shape of a surface, a distortion, etc. which arise when a sheet winds around a 1st roll arise. On the other hand, when it is higher than this range, since the generation of a flow mark and the shaping | molding sheet may be wound around a 1st roll, it is unpreferable. In addition, it is not preferable because the possibility of occurrence of poor optical performance due to appearance impairment such as wavy shape, torsion, non-uniform thickness of the finished sheet, or impairment of running of the sheet due to poor external contact to the second roll may occur. Can not do it.

The set temperature T2 of the second roll is Tg + 20 ° C to Tg + 60 ° C, more preferably Tg + 30 ° C to Tg + 50 ° C, and more preferably Tg + 40 ° C to Tg + 50 ° C. Further, the set temperature T3 of the third roll to be the molding roll is Tg + 20 ° C to Tg + 60 ° C, more preferably Tg + 30 ° C to Tg + 50 ° C, more preferably Tg + 40 ° C to Tg + 50 ° C. Moreover, when providing said take off roll as a 4th roll, it is preferable to set the preset temperature T4 of a 4th roll as Tg-50 degreeC-Tg + 30 degreeC. If the temperature setting is out of these ranges, the driving failure due to the bending of the sheet on the roll or the transfer of the optical element will be incomplete, and the appearance failure such as the wavy shape of the surface of the finished sheet, the distortion, etc. This increases the risk of occurrence of poor optical performance, which is undesirable.

When shaping | molding in 100 degreeC or more for temperature control of a roll, it is preferable to use a fruit oil. Roll temperature in this invention means the temperature of the roll which can be measured. As temperature which can be measured, although there exists a roll surface temperature or the temperature of the fruit used for temperature control of a roll, from the viewpoint of operation, the temperature of the fruit used for temperature control of a roll can be used preferably.

Although there is no restriction | limiting in particular in the thickness of a sheet, From the point of using as an optical sheet, it is preferable to be 5 mm or less, More preferably, it is 3 mm or less, More preferably, it is 2 mm or less.

<Shape, material of roll>

In the present invention, the first roll, the second roll, and the third roll may be a material that does not cause deformation or the like even when heated or cooled until the thermoplastic resin forming the sheet can be adjusted to a moldable temperature. Can be used suitably. Each of these rolls can be independently adjusted to an arbitrary temperature by heating, a heater, or the like, and the rotation speed of the rolls must also be independently adjustable.

The take-up roll can be made of any material so long as it does not damage the uneven shape of the resin material, and the slip of the roll is unlikely to occur. For example, a 60-90 degree material etc. can be employ | adopted as the rubber hardness prescribed | regulated by JISK6301. When the roll surface uses such a rubber-hard take-up roll, the slip of the roll hardly occurs without damaging the uneven shape of the resin material, and the sheet can be produced efficiently. The surface shape of the take-up roll may be any shape as long as it can be taken up without deforming the surface shape molded by the first, second and third rolls and without running obstacles such as slip. The rotation speed of a roll can be adjusted independently with each takeup roll and the 1st-3rd roll. The temperature of the take-up roll may be adjustable. The take-up roll preferably has a sheet surface temperature of Tg or lower, preferably Tg-30 ° C or lower, but it is not necessary to perform temperature adjustment. Moreover, the roll for adjusting the running of a sheet | seat can also be suitably formed between a 3rd roll and a take-up roll.

Next, the optical sheet manufactured by this invention is demonstrated.

<Thermoplastic Resin of Optical Sheet>

The thermoplastic resin constituting the optical sheet according to the present invention is not particularly limited as long as it is transparent and has appropriate strength as a component that is the center of the optical sheet. Polycarbonate resins; Acrylic resins such as polymethyl methacrylate; Styrene resins such as polystyrene, polyvinyl toluene and poly (p-methylstyrene); MS resin (copolymer of methyl methacrylate and styrene); Norbornene-based resins; Polyarylate resins; Polyethersulfone resins; Ring structure-containing polymer resins; Of these, two or more kinds of mixed resins can be used. Suitably, polycarbonate resin, styrene resin, norbornene resin, or ring structure-containing polymer resin is used. Especially, since polycarbonate resin is excellent in transparency, heat resistance, and workability, and their balance is good, it is especially preferable as resin for optical sheets. Moreover, since ring structure-containing polymer resin is excellent in optical performance, this is also especially preferable as resin for an optical sheet.

The polycarbonate resin is obtained by reacting a dihydric phenol with a carbonate precursor by an interfacial polycondensation method or a melting method. Representative examples of the dihydric phenol include 2,2-bis (4-hydroxyphenyl) propane [common name bisphenol A], 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy Phenyl) cyclohexane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl ) Sulfide, bis (4-hydroxyphenyl) sulfone, and the like, and bisphenol A is particularly preferred. These dihydric phenols can be used individually or in mixture of 2 or more types.

Carbonyl halide, carbonate ester, haloformate, etc. are used as a carbonate precursor, Specifically, phosgene, diphenyl carbonate, dihaloformate of a dihydric phenol, etc. are mentioned.

In preparing the polycarbonate resin by reacting the dihydric phenol and the carbonate precursor by an interfacial polycondensation method or a melting method, a catalyst, an end terminator, an antioxidant for preventing the oxidation of the dihydric phenol and the like can be used. . The polycarbonate resin may be a branched polycarbonate resin copolymerized with a trifunctional or higher polyfunctional aromatic compound, or may be a polyester carbonate resin copolymerized with an aromatic or aliphatic bifunctional carboxylic acid, or two kinds of polycarbonate resins obtained. The mixture which mixed the above may be sufficient. As a polycarbonate resin used for this invention, it is preferable to use the polycarbonate resin obtained by the interfacial polycondensation method (common name; phosgene method). Further, direct sheet extrusion of polycarbonate resin which does not melt the resin such as an extruder or kneader is more preferable since it is possible to prevent discoloration due to thermal history.

The molecular weight of polycarbonate resin is represented by the viscosity average molecular weight, and is usually 15,000 to 40,000, preferably 18,000 to 35,000. The viscosity-average molecular weight referred to in the present invention is calculated by inserting the specific viscosity (ηsp) calculated from a solution in which 0.7 g of polycarbonate resin is dissolved in 100 ml of methylene chloride at 20 ° C in the following formula.

ηsp / c = [η] + 0.45 × [η] ² c

[η] = 1.23 × 10 ^-4 M ^{0 .83}

(Where c = 0.7 and [η] is the limit viscosity)

In the polycarbonate resin, other components such as phosphorous acid, phosphoric acid, phosphite ester, phosphate ester, and phosphonic acid ester in the range not impairing the purpose and effect in addition to the above components, triazoles, acetophenones and salicylic acid esters Additives such as ultraviolet absorbers, bluing agents, low molecular weight polycarbonates of tetrabromobisphenol A, tetrabromobisphenol A, flame retardants such as decabromodiphenylene ether, and flame retardant aids such as antimony trioxide. You may mix | blend the quantity which the effect expresses.

The said phosphorus containing heat stabilizer can prevent the fall of the molecular weight at the time of shaping | molding, or deterioration of a hue. Specific examples of such phosphorus-containing heat stabilizers include phosphite compounds such as triphenyl phosphite, phosphate compounds such as tributyl phosphate, and phosphates such as bis (2,4-di-tert-butylphenyl) -biphenylphosphinite. Phosphonic acid ester type compounds, such as a pinite type compound and benzene phosphonate dimethyl, etc. are mentioned, Especially, a tris (2, 4-di-tert- butylphenyl) phosphite and a tetrakis (2, 4-di- Preference is given to tert-butylphenyl) -4,4'-biphenylenediphosphinite and bis (2,4-di-tert-butylphenyl) -biphenylphosphinite.

You may use these thermal stabilizers 1 type or in mixture of 2 or more types. As for the usage-amount of such a thermal stabilizer, 0.001-0.15 mass part is preferable with respect to 100 mass parts of polycarbonate resins.

Moreover, a fatty acid ester compound can be mix | blended with polycarbonate resin for the purpose of improving the releasability from the metal mold | die at the time of shaping | molding. As such fatty acid ester, it is preferable that they are partial ester or all ester of C1-C20 monohydric or polyhydric alcohol, and C10-C30 saturated fatty acid. As such partial esters or total esters of monohydric or polyhydric alcohols with saturated fatty acids, monostearate, stearic acid diglycerides, stearic acid triglycerides, stearic acid monosorbate, behenic acid monoglycerides, pentaerythritol monostearate , Pentaerythritol tetrastearate, pentaerythritol tetrafelagonate, propylene glycol monostearate, stearyl stearate, palmityl palmitate, butyl stearate, methyllaurate, isopropyl palmitate, biphenylbiphenate, sorbitan Monostearate, 2-ethylhexyl stearate, and the like, among which monostearate monoglyceride, tristearate triglyceride, and pentaerythritol tetrastearate are preferably used. As for the usage-amount of such fatty acid ester, 0.001-0.5 mass part is preferable with respect to 100 mass parts of polycarbonate resins.

As the thermoplastic resin constituting the optical sheet of the present invention, a ring structure-containing polymer resin can also be suitably used. As the ring structure-containing polymer resin, a thermoplastic acrylic copolymer having a ring structure in the main chain is preferable. In the main chain, a ring structure and a structure derived from a (meth) acrylate monomer are included. The sum total of the content rate of the structural unit derived from a (meth) acrylate-type monomer, and the content rate of a ring structure is 50 mass% or more in a copolymer, More preferably, it is 70 mass% or more, More preferably, 90 mass% Especially preferably, it contains 95 mass% or more, Most preferably, it contains 99 mass% or more.

The ring structure of the main chain usually has positive birefringence, and since the structure derived from the (meth) acrylate monomer has a weak negative birefringence, the positive birefringence and the (meth) acrylate monomer by the ring structure of the main chain The negative birefringence due to the derived structure is negated with each other, so that a film having a low birefringence can be obtained even after stretching. Here, positive birefringence refers to expressing refractive anisotropy such that the refractive index in the same direction becomes large when the molecular molecular chains constituting the film are oriented by stretching. On the other hand, negative birefringence refers to a refractive index such that when the molecular molecular chain which is a component constituting the film is stretched, the molecular orientation is reduced and the refractive index in the same direction becomes smaller and at the same time the refractive index in the orthogonal direction becomes larger. It expresses anisotropy.

As a specific example of the (meth) acrylate monomano which comprises the ring structure containing polymer resin, Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acryl (Meth) acrylic-acid alkylesters, such as a rate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate; Benzyl (meth) acrylate; Chloromethyl (meth) acrylate; 2-chloromethyl (meth) acrylate; Dicyclopentanyloxyethyl (meth) acrylate; Dicyclopentanyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate; 3-hydroxypropyl (meth) acrylate; 2,3,4,5-pentahydroxyhexyl (meth) acrylate; 2,3,4,5-tetrahydroxyhexyl (meth) acrylate etc. are mentioned, Among these, 1 type (s) or 2 or more types can be used. Especially, (meth) acrylic-acid alkylester is preferable at the point which is excellent in thermal stability and an optical characteristic, and methyl methacrylate is especially preferable.

Although monomers other than a (meth) acrylate type monomer can also be used to comprise ring structure containing polymer resin, For example, Styrene-type monomers, such as styrene and (alpha)-hydroxyethyl styrene; Acrylonitrile; Olefins such as methyl vinyl ketone, ethylene, propylene and 4-methyl-1-pentene; Vinyl acetate; Allyl alcohols such as metaallyl alcohol, allyl alcohol, and 2-hydroxymethyl-1-butene; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; 2- (hydroxyalkyl) acrylic acid esters such as methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate; N-vinylpyrrolidone; N-vinylcarbazole, etc. are mentioned. These monomers may use only 1 type or may use 2 or more types together.

As ring structure of main chain, N-substituted maleimide, such as phenyl maleimide, benzyl maleimide, cyclohexyl maleimide, methyl maleimide, and maleic anhydride are copolymerized, and ring structure derived from N-substituted maleimide, and derived from maleic anhydride The ring structure of may be introduced, or a lactone ring structure, a glutaric anhydride structure, a glutalimide structure, a ring structure derived from N-substituted maleimide, or the like may be introduced into the main chain by a cyclization reaction after polymerization. . From heat resistance, it is preferable to have a ring structure derived from N-substituted maleimide, a lactone ring structure, and a glutalimide structure, and among them, having a lactone ring structure in the main chain in view of low coloration and excellent optical properties. Is particularly preferred.

The manufacturing method of the thermoplastic acrylic copolymer which has a ring structure in a principal chain can apply a well-known manufacturing method. For example, the manufacturing method of the acrylic resin containing a lactone ring structure is described in Unexamined-Japanese-Patent No. 2006-96960, Unexamined-Japanese-Patent No. 2006-171464, and Unexamined-Japanese-Patent No. 2007-63541. Moreover, about the thermoplastic acrylic copolymer which copolymerized N-substituted maleimide, and the thermoplastic acrylic copolymer containing glutaric anhydride structure and glutalimide structure, Unexamined-Japanese-Patent No. 2007-31537, WO2007 / 26659, WO2005 / The manufacturing method of the description of 108438 etc. can be used.

About the lactone ring structure of a principal chain, although a 4-8 membered ring may be sufficient, a 5-6 membered ring is more preferable from a stability of a structure, and a 6-membered ring is still more preferable. Moreover, when the lactone ring structure of a principal chain is a 6-membered ring, the structure of General formula (1) and Unexamined-Japanese-Patent No. 2004-168882, etc. are mentioned, The polymerization yield is simultaneously synthesize | combining the polymer before introducing a lactone ring structure into a principal chain. It is preferable that it is a structure of following General formula (1) from the point which is easy to obtain a high polymer with a high content of the lactone ring structure, and also the copolymerizability with (meth) acrylates, such as methyl methacrylate, is good. Do.

In the above formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. In addition, the organic residue may include an oxygen atom.

The content ratio of the ring structure is preferably 15% by mass or less in the copolymer, more preferably 1-15% by mass, still more preferably 3-15% by mass, particularly preferably 5-12% by mass, most preferably. Preferably it is 5-10 mass%. If the content ratio of the ring structure is more than 15% by mass, since the positive birefringence is increased, it is not preferable. By having the said ring structure, heat resistance, solvent resistance, and surface hardness improve.

As for Tg of the said thermoplastic acrylic copolymer, 110 degreeC or more is preferable. More preferably, it is 115 degreeC or more, More preferably, it is 120 degreeC or more. Although the upper limit of Tg is not specifically limited, From moldability, 200 degrees C or less is preferable. The weight average molecular weight of the thermoplastic acrylic copolymer is preferably 10,000 to 300,000, more preferably 50,000 to 300,000, more preferably 100,000 to 250,000, particularly preferably 120,000 to 200,000.

<Adjustment of Optical Sheets>

Although the thickness of the optical sheet of this invention does not have a restriction | limiting in particular, From the point of using as an optical sheet, it is preferable to set it as 5 mm or less, More preferably, it is 3 mm or less, More preferably, it is 2 mm or less. Moreover, although it may consist of only transparent resin, in order to adjust light diffusivity, a light-diffusion layer can be formed. The light diffusing layer can be uniformly or randomly dispersed in the entire optical sheet, only the lens portion, all other than the lens portion, only the light-emitting surface surface layer, only the light-emitting surface surface layer, or the intermediate layer. In the light diffusion layer, light diffusing particles are dispersed in a thermoplastic resin, and diffuse light in a predetermined direction.

Although the thickness of a light-diffusion layer can be suitably adjusted according to the thickness of an optical sheet, it does not restrict | limit especially, Usually, it can be made into about 0.005 mm or more and 5 mm or less. This is because if it is less than 0.005 mm, the light diffusion effect cannot be sufficiently exhibited, and if it exceeds 5 mm, the overall device may not be compacted beyond the upper limit of the thickness of the optical sheet of the present invention.

<Light diffusing particle>

The optical sheet of the present invention may have light diffusing particles. As a material of light-diffusion particle | grains, For example, synthetic resins, such as (meth) acrylic-type resin, styrene resin, polyurethane resin, polyester resin, silicone resin, fluorine-type resin, these copolymers; Glass; Clay compounds such as smectite and kaolinite; Inorganic oxides such as silica and alumina; Etc. can be mentioned. Among these materials, (meth) acrylic resins, silicone resins and silicas are particularly suitable.

The usage-amount of light-diffusion particle | grains becomes like this. Preferably it is 0.005 mass part or more, 20 mass parts or less, More preferably, it is 0.01 mass part or more and 10 mass parts or less with respect to 100 mass parts of thermoplastic resins which comprise an optical sheet. When the amount of use is less than 0.005 parts by mass, the light incident on the optical sheet may not be diffused sufficiently to exhibit the expected effect of the fine particles. On the contrary, when the amount of use exceeds 20 parts by mass, extrusion of the optical sheet may be difficult, or the amount of light to be transmitted may decrease, resulting in a decrease in luminance. In addition, it is possible to have a laminated structure in which the light diffusing layer having the light diffusing particles is part of the optical sheet of the present invention. At this time, the family usage amount is the family usage amount in the light diffusion layer. The thermoplastic resin of the light diffusion layer may be the same or different as the thermoplastic resin constituting the optical sheet other than the light diffusion layer.

When using organic fine particles obtained by radical polymerization as light diffusing particles, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) as raw material monomers of the fine particles. Acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclo (Meth) acrylates, such as hexyl (meth) acrylate, benzyl (meth) acrylate, hydroxyethyl (meth) acrylate, and hydroxypropyl (meth) acrylate; Styrenes such as styrene, p-methylstyrene, vinyltoluene, and p-t-butylstyrene; Maleimides such as N-phenylmaleimide, N-cyclohexyl maleimide, and N-benzyl maleimide; (Meth) acrylamides, such as (meth) acrylamide and N-methylol (meth) acrylamide; Acrylonitriles such as (meth) acrylonitrile; N-vinylpyrrolidone; 1 type or 2 or more types of these can be mixed and used.

In addition, when using the crosslinked organic fine particles obtained by radical polymerization as light-diffusing particles, in addition to the above monomers, ethylene glycol di (meth) acrylate and diethylene glycol di (meth) are used as raw material monomers for crosslinking. Polyfunctional (meth) such as acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, bishydroxyethyl bisphenol A di (meth) acrylate ) Acrylate; Radical polymerizable crosslinking agents such as divinyloxyethoxy (meth) acrylate, diallyl phthalate, allyl (meth) acrylate, and divinylbenzene; Polyfunctional epoxy compounds such as bisphenol A diglycidyl ether, diethylene glycol diglycidyl ether and neopentyl glycol diglycidyl ether; Polyfunctional isocyanate compounds such as tolylenedisocyanate, xylylenedisocyanate and isophoronedisocyanate; 1 type of polyfunctional methylol compounds, such as N-methylol melamine and N-methylol benzoguanamine; or 2 or more types of these can be mixed and used.

The refractive index of the light diffusing particles is different from the refractive index of the thermoplastic resin constituting the optical sheet or the light diffusing layer. When organic fine particles having the same refractive index are used, light is not refracted, and the uniformity of luminance cannot be sufficiently increased. However, since the refractive index of resin differs according to the kind, the kind of resin and thermoplastic resin which comprise light-diffusion particle | grains can be made into another thing. Moreover, crosslinkable particle | grains and particle | grains which are not can also be mixed and used as a selection of particle | grains.

An antioxidant can be further mix | blended with the thermoplastic resin which comprises the light-diffusion particle | grain or optical sheet of this invention. Since antioxidant can suppress coloring of the optical sheet and light-diffusion particle by oxidation and deterioration at the time of heat shaping | molding, the brightness | luminance of the light source unit to which the optical sheet of this invention is applied can be exhibited more reliably.

As antioxidant, a conventionally well-known thing can be used. For example, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] or octadecyl-3- (3,5-di-t-butyl-1- Hindered phenol-based antioxidants such as hydroxyphenyl) propionate; Tris (2,4-di-t-butylphenyl) phosphite or tris [2-[[2,4,8,10-tetra-t-butyldibenzo [d, f] [1,3,2] di Phosphorus antioxidants such as oxaphosphine-6-yl] oxy] ethyl] amine; Pentaerythryl tetrakis (3) having an aromatic ring and having no aromatic ring, such as thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Sulfur-based antioxidants such as laurylthiopropionate); Lactone-based antioxidants such as reaction products of 3-hydroxy-5,7-di-t-butyl-furan-2-one and o-xylene; Hydroxylamine antioxidants such as oxidation products of alkylamines using reduced tallow as a raw material; Vitamin E antioxidants such as 3,4-dihydro-2,5,7,8-tetramethyl-2- (4,8,12-trimethyltridecyl) -2H-benzopyran-6-ol and the like can be used. Can be.

Although the usage-amount of antioxidant can be adjusted suitably, 0.05 mass part or more and about 0.3 mass part or less can be added with respect to 100 mass parts of thermoplastic resins or light-diffusion particles normally.

<Optical element of optical sheet>

On at least one surface of the optical sheet of the present invention, a lens group is formed as an optical element. The lens in the present invention is a lens, each of which is independent like a prism, a certain length, an isosceles triangle, an isosceles triangle, a part of an ellipse, a part of a circle, a part surrounded by a parabola, or a shape thereof. And an almost ridge-shaped lens having a cross-sectional shape such as a composite of the above, and refers to a lens capable of diffusing or condensing incident light within a certain viewing angle. An almost ridge lens is a lens in which the cross-sectional shape continuously grows in the sheet longitudinal direction (take-up direction).

In the case where each one is an independent lens, one lens shape is not particularly limited as long as it can diffuse light in the sheet width direction (direction perpendicular to the sheet length direction), but is not limited to prisms (four-corner pyramid). Such as cutting a jujube, hemisphere, or rugby ball along a major axis, such as a truncated lens such as a three-corner, five-corner, six-corner, or cone, or a region near the apex of these cones in a plane parallel to the base. A half-spherical sphere etc. are mentioned. When each one is an independent lens, it is preferable to perform the surface processing of the molding roll so that each lens may be provided substantially parallel to the longitudinal direction of an optical sheet.

In addition, the cross-sectional shape of the almost ridge-shaped lens is not particularly limited as long as it can diffuse light in the sheet width direction (the direction orthogonal to the sheet length direction). For example, an isosceles triangle, an isosceles triangle, a part of a circle, an ellipse Part, parabolic, rectangular at the bottom and semicircular at the top (see FIG. 6). The top angle of the isosceles triangle can be greater than 60 ° and less than 120 °. Moreover, the center angle of a part of a circle is not limited to 180 degrees, but can be adjusted so that light may be spread in a fixed direction.

Each lens need not necessarily be the same shape. As shown in FIG. 7, the height of the top portion and / or the depth of the valley portion may be different, and other states of them may be periodic at any interval. Based on the respective optical design, the optical element only needs to be surface molded accurately.

As described above, depending on the designed optical performance, the top and valley portions of the optical element may not have a constant height and depth. However, the optical element may not be precisely transferred to some extent and molded on the surface of the sheet. If not, high optical performance will not be achieved. In terms of the shape and arrangement of the lens in which the accurate transfer effect of the present invention occurs, the average gap between the top and the top, or the average gap between the valley and the valley (so-called lens pitch) is preferably in the range of 10 to 200 µm. More preferably, it is the range of 30-160 micrometers, and this uniformity of optical performance can be improved by transferring this setting correctly to a sheet | seat. Moreover, the average value of the length of the waterline (so-called lens height) which fell from the top part in the straight line which connects the valley parts adjacent to both sides is 0.2: 1.0-about the average gap of the top part and the tower part, or the average gap of the valley part and the valley part. The range of 0.8: 1.0 is preferable, and the range of 0.3: 1.0 to 0.7: 1.0 is more preferable for enhancing optical characteristics.

A plurality of lenses are formed on at least one surface of the optical sheet of the present invention. Although space | interval may be provided between mutually adjacent lenses, it is made to adjoin without space | interval suitably in order to improve light diffusion efficiency. The lens can be formed over the entire length of the optical sheet, but in order to fix it with other members, the end portion can be in a flat state.

Resin which comprises a lens can use the same thing as resin which comprises an optical sheet, and although resin other than a lens part and a lens part may be different, it is set as the same resin normally. Further, in the thermoplastic resin constituting the lens, the same light diffusing particles (crosslinked organic fine particles, etc.) as those dispersed in the light diffusing layer can be dispersed. It is preferable that the major axis direction of the said light-diffusion particle | grains (crosslinked organic microparticles | fine-particles etc.) is substantially the same as the longitudinal direction of an optical sheet.

<Function other than optical element of optical sheet>

In the optical sheet of the present invention, an ultraviolet absorber, an antistatic agent, a lubricant, and a near infrared absorber can be used within a range not impairing the spirit of the present invention. In particular, on the surface set on the light source side, it is preferable that a layer containing an ultraviolet absorber, a layer containing an antistatic agent, or both an ultraviolet absorber-containing layer and an antistatic agent-containing layer are formed. That is, a layer having an action other than light scattering may be formed on at least one side of the optical sheet (light diffusing layer). Although it is preferable to provide a ultraviolet absorber containing layer at least on the light source opposing surface side of a 1st optical sheet, from a viewpoint of the maintenance of the function in the installation environment of various light source apparatuses, and the storage environment of a member, and elongate from both surfaces, You may form. Similarly, the antistatic agent-containing layer may be provided only on one side or on both sides of the first optical sheet. Moreover, the whole 1st optical sheet may be an antistatic agent containing layer or a ultraviolet absorber containing layer. The layer having a function different from those of the light diffusing function reduces ultraviolet rays generated from the light emitting body to suppress coloring of the optical sheet, further suppresses charging, thereby suppressing a decrease in luminance due to adhesion of dust, or life of an electronic device. The optical sheet of the present invention is provided with a function such as extending the length of the film.

As a ultraviolet absorber and an antistatic agent, a conventionally well-known thing can be used. For example, as a ultraviolet absorber, a salicylic acid phenyl ester type ultraviolet absorber; Benzophenone ultraviolet absorbers; Triazine ultraviolet absorbers; Benzotriazole ultraviolet absorbers; Cyclic imino ester type ultraviolet absorbers; A hybrid ultraviolet absorber having a hindered phenol structure and a hindered amine structure in a molecule thereof; Triphenyl cyano acrylate type ultraviolet absorber; Oxalic anilide ultraviolet absorbers; Malonic acid ester ultraviolet absorbers; A low molecular weight ultraviolet absorber such as these, and a high molecular weight ultraviolet absorber (for example, Hals Hybrid (registered trademark) manufactured by Nippon Shokubai Co., Ltd.), which are bonded in a form in which these low molecular weight ultraviolet absorbers are suspended in a polymer can be used. Especially, triphenyl cyanoacrylate type ultraviolet absorber; Oxalic anilide ultraviolet absorbers; The malonic acid ester ultraviolet absorber is preferable because the absorption of light in the visible light region is small. When used for polycarbonate resin, an oxalic acid anhydride type ultraviolet absorber and malonic acid ester type ultraviolet absorber are more suitable.

As an antistatic agent, Alkyl sulfonic acid, alkylbenzene sulfonic acid, olefin type sulfate esters, such as those Li, Na, Ca, Mg, Zn salt, or its metal salt; Anionic surfactants such as phosphoric acid esters of higher alcohols; Cationic surfactants such as tertiary amines, quaternary ammonium salts, cationic acrylic ester derivatives and cationic vinyl ether derivatives; Amphoteric surfactant, such as the positive salt of alkylamine-type betaine, the positive salt of carboxylic acid alanine or sulfonic acid alanine, and the positive salt of alkyl imidazoline; Nonionic surfactants such as fatty acid polyhydric alcohol esters and polyoxyethylene adducts of alkyl (amine); Polyamide elastomer, such as polyether esteramide and polyesteramide, etc. can be used. In addition, conductive resins such as polyvinyl benzyl cationic resin and polyacrylic acid cationic resin can also be used as antistatic agents.

Although the usage-amount of a ultraviolet absorber and an antistatic agent can be adjusted suitably according to each function, it is about 1-50 mass parts with respect to 100 mass parts of resin which comprises each layer normally. The layer having a function different from those of the light diffusing function can adhere the sheet obtained by uniformly dispersing the ultraviolet absorber or the antistatic agent in the same thermoplastic resin as the light diffusing layer onto the optical sheet or the like by thermocompression bonding or an adhesive. Or after apply | coating the paste containing a ultraviolet absorber etc. on an optical sheet, it can dry or cool. Moreover, the thermoplastic resin which mix | blended the light-diffusion agent and the thermoplastic resin which mix | blended the ultraviolet absorber and antistatic agent can be coextruded. Although the thickness of these layers may be adjusted suitably according to each function etc., it can usually be about 1-50 micrometers.

The size and shape of the optical sheet of the present invention are not particularly limited, and can be matched to the size and shape of a liquid crystal display device, for example. By doing so, it is possible to construct a light source unit having excellent optical characteristics. In addition, by combining the light source unit of the present invention with a liquid crystal panel in a conventional manner, a liquid crystal display device having excellent optical performance can be constituted.

Example

<About an Example>

< Manufacturing example  1>

Polycarbonate resin (`` Eupilon (registered trademark) E2000FN '': 100 parts of Mitsubishi Engineering Plastics Co., Ltd., glass transition point (Tg) = 150 ° C), and phosphorus-based heat stabilizer (`` Iruga Force (registered trademark) 168 '': Chibazer Pan Corporation) ) 0.1 part, 0.003 parts of oxazole-based fluorescent brightener (“UBITEX (registered trademark) OB” manufactured by Chiba Japan Corporation) were supplied to a sheet extruder having three rolls equipped with a vent and a gear pump in the configuration of FIG. At the exit temperature of 265 ° C, the first roll temperature of 140 ° C, the second roll temperature of 188 ° C, and the third roll temperature of 193 ° C, extrusion of an optical sheet having a die width of 1150 mm and a thickness of 1.2 mm was performed. The first and second rolls use mirror flat rolls, and the third roll has a lens pitch of 100 microns and a lens height of 50 microns in which an elliptic ridge lens is molded to be molded (the direction of the lens ridge is Pieces) to be parallel to the rotational direction of the roll. The peripheral speed of the 3rd roll was 2.0 m / min, and the peripheral speed of the take-up roll was 2.06 m / min, and operation for manufacturing an optical sheet was performed.

< Manufacturing example  2>

Except having made the circumferential speed of the take-up roll into 2.6 m / min, operation | movement for manufacturing an optical sheet was performed on the conditions similar to manufacture example 1 altogether.

< Manufacturing example  3>

Except having made the circumferential speed of the take-up roll 2.3 m / min, the operation | movement for manufacturing an optical sheet was performed on the same conditions as the manufacture example 1 altogether.

< Manufacturing example  4>

Except having made the 1st roll temperature of 125 degreeC, the 2nd roll temperature of 197 degreeC, and the 3rd roll temperature of 193 degreeC, operation | movement for manufacturing an optical sheet was performed on the conditions similar to manufacture example 1 altogether.

< Manufacturing example  5>

Except having made the 1st roll temperature of 135 degreeC, the 2nd roll temperature of 191 degreeC, and the 3rd roll temperature of 191 degreeC, operation for manufacturing an optical sheet was performed on the same conditions as the manufacture example 1 all.

< Manufacturing example  6>

The main speed of a take-up roll is 2.3 m / min, 1st roll temperature 135 degreeC, 2nd roll temperature 191 degreeC, and 3rd roll temperature 191 degreeC, without adjusting temperature between a 3rd roll and a takeup roll. The operation for manufacturing the optical sheet was carried out under the same conditions as in Production Example 3, except that the take-off roll that did not adjust the circumferential speed was provided.

< Manufacturing example  7>

Except having made temperature of a takeoff roll into 130 degreeC, operation for manufacturing an optical sheet was performed on all the conditions similar to the manufacture example 6.

< Manufacturing example  8>

Except having made the circumferential speed of the take off roll into 2.3 m / min, operation | movement for manufacturing an optical sheet was performed on all the conditions similar to manufacture example 7.

< Manufacturing example  9>

Except having used the mat roll (arithmetic surface roughness Ra = 4.0 micrometer) for the 2nd roll, the operation | movement for manufacturing an optical sheet was performed on the conditions similar to manufacture example 4 altogether.

< Manufacturing example  10>

Except having used the embossing roll (arithmetic surface roughness Ra = 0.25micrometer) for the 2nd roll, the operation | movement for manufacturing an optical sheet was performed on the conditions similar to manufacture example 4 altogether.

<Comparison Manufacturing example  1>

Except having made the circumferential speed of the take-up roll 2.0 m / min, operation | movement for manufacturing an optical sheet was performed on the same conditions as the manufacture example 1 altogether.

<Comparison Manufacturing example  2>

Except having made the circumferential speed of the take-up roll into 2.8 m / min, operation | movement for manufacturing an optical sheet was performed on all the conditions similar to the manufacture example 1.

<Comparison Manufacturing example  3>

Except having made the circumferential speed of the take-up roll 3.0m / min, operation | movement for manufacturing an optical sheet was performed on all the conditions similar to the manufacture example 1.

<Note Manufacturing example  1>

The first and third rolls are mirror rolls, and the second roll is sculpted so that an almost elliptical ridge lens with a lens pitch of 100 microns and a lens height of 60 microns can be molded (the direction of the lens ridge is Except for using the pieces) so as to be parallel to the rotational direction, the operation for producing the optical sheet was carried out under the same conditions as in Production Example 1.

<Note Manufacturing example  2>

Except having made the 1st roll temperature of 155 degreeC, the 2nd roll temperature of 210 degreeC, and the 3rd roll temperature of 210 degreeC, operation for manufacturing an optical sheet was performed on the conditions similar to manufacture example 1 altogether.

<Note Manufacturing example  3>

Except having made the 1st roll temperature of 125 degreeC, the 2nd roll temperature of 145 degreeC, and the 3rd roll temperature of 165 degreeC, operation for manufacturing an optical sheet was performed on the conditions similar to manufacture example 1 all.

<About driving>

For continuous operation for 6 hours, operation failure appeared without the need to make fine adjustment by applying the fine adjustment, stable operation is possible by adding fine adjustment, and without fine adjustment from the initial setting conditions. What stopped was evaluated by x. The results are summarized in Table 1.

<Molding rate>

The measurement of the molding rate was performed by SEM imaging of the lens pitch and the lens height at the central portion in the width direction of the obtained optical sheet, the lens height / lens pitch of the optical sheet was calculated, and the value thereof was measured by the lens of the mold (piece) roll. It carried out by dividing by height / lens pitch. For example, the lens pitch of the optical sheet obtained in Example 1 is 98.5 microns, the lens height is 48.3 microns, and the mold pitch is 100 microns and the lens height is 50 microns, so the (molding ratio) = ( 48.3 / 98.5) x 100 / (50/100) = 98 (%). The closer to 100 this value is, the better the molding property is. The results are summarized in Table 1.

<About uniformity>

The measurement of uniformity was performed by taking 9 points of samples in the width direction of the obtained optical sheet, measuring each lens pitch by SEM imaging, and measuring the ratio of minimum value / maximum value. For example, since the minimum lens pitch of the optical sheet obtained in Example 1 is 98.0 microns and the maximum lens pitch is 99.2 microns, (uniformity) = (98.0 / 99.2) x 100 = 99 (%). The closer to 100 this value is, the better the molding property is. The results are summarized in Table 1.

<About thickness precision>

The thickness was measured using a micrometer with respect to the TD (Transverse Direction: width direction) direction of the obtained optical sheet disc using a micrometer. The difference between the maximum thickness and the minimum thickness was calculated and divided by the average value of the thicknesses of five places. For example, since the difference between the maximum thickness and the minimum thickness of the optical sheet obtained in Example 1 is 0.03 mm, and the average value of the thicknesses of five places is 1.19 mm, (thickness precision) = (0.03 / 1.19) x 100 = 2.5 (%). It is judged that the smaller the value, the better the thickness precision. The results are summarized in Table 1.

<About warping>

The sheet (1000 mm × 1000 mm) cut from the obtained optical sheet disc was allowed to stand for 1 h on a surface plate installed in a room with a temperature of 23 ° C. and a humidity of 60%. It was. The deflection of less than 2mm is ○, the thing of more than 2mm and less than 3mm is △, the thing of more than 3mm is x.

<Optical Performance>

Optical performance was measured by the following method. The backlight part mounted in the thin liquid crystal television (WOOOO UT-32-HV700) by Hitachi Ltd. was taken out, and it was set as the light source for luminance measurement. Each optical sheet obtained by Production Examples and Comparative Production Examples was cut into a size that can be incorporated into the light source (* nearly the ridge direction of the elliptic ridge-shaped lens was parallel to the long side direction of the sheet; i.e., nearly the cold cathode tube of the backlight The elliptical ridge lens in the direction in which the ridge lines are parallel to each other) and the lens surface in the opposite direction to the light source. On top of that, one 32-inch prism sheet (UTE-30; manufactured by MN Tech) and one microlens sheet (UTE-21; manufactured by MN Tech) are used so that the lens surface faces the light source in the opposite direction. Installed on the bed.

Subsequently, the cold cathode tube was turned on, and the brightness | luminance directly in the former: cold cathode tube, and the luminance between the cold cathode tube and cold cathode tube were measured using the color | collar luminance meter (BM-7) made from Topcon. The temperature of the atmosphere was 25 ° C., the humidity was 60% RH, the measurement distance was 50 cm from the cold cathode tube (the distance in the normal direction to the backlight surface), and the viewing angle was 0.2 °. In addition, the brightness | luminance and brightness | variation deviation were computed by the following formula. The results are summarized in Table 1.

Luminance = (A +) / 2

Luminance deviation (%) = | former-| × 100 / luminance

(Industrial availability)

By this invention, the optical sheet which has a surface shape which fully exhibits original design performance can be manufactured efficiently. Moreover, since the molding of the roll surface is transferred as optically designed, the optical sheet of this invention manufactured in this way exhibits the outstanding performance especially as an optical sheet. The light source unit and the display device using the optical sheet also exhibit excellent performance.

1: die
2: first roll
3: second roll
4: 3rd roll (surface molding roll)
5a: take-up roll a
5b: take-up roll b
6: take off roll

Claims (9)

In the manufacturing method of the optical sheet which is surface-molded by using the molding roll surface-processed so that an almost ridge-shaped optical element is molded in substantially parallel with the take-up direction of a sheet | seat,
When the molding roll is installed on the third roll and the main speed of the molding roll is Va and the main speed of the take-up roll (draw roll) is Vb, the main speed Vb is 103 to 130% of the main speed Va. The manufacturing method of the optical sheet characterized by the above-mentioned. 2. An optical element according to claim 1, wherein the optical element is molded almost parallel to the take-up direction, and the cross-section is substantially arranged with a plurality of convex or convex tops and a plurality of concave or concave valleys alternately substantially parallel in alternation. A method for producing an optical sheet which is a ridge-shaped optical element. The method for producing an optical sheet according to claim 2, wherein the interval between the top and the top of the substantially ridge-shaped optical element, or the interval between the valley and the valley, is 200 µm or less. It was produced by the manufacturing method in any one of Claims 1-3, The optical sheet characterized by the above-mentioned. The optical sheet of Claim 4 was used, The light source unit characterized by the above-mentioned. A display device comprising the light source unit according to claim 5. The method of manufacturing an optical sheet according to claim 1, wherein the first roll is a mirror roll, and the second roll is a mirror roll, a mat roll, or an emboss roll. The manufacturing method of an optical sheet according to claim 1, wherein a take-off roll is provided between the molding roll (third roll) and the take-up roll. The manufacturing method of the optical sheet of Claim 1 which sets the temperature of a molding roll (third roll) to Tg + 20 degreeC-Tg + 60 degreeC, when the glass transition temperature of the thermoplastic resin to be used is Tg.

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