JP2013148605A - Reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflector which effectively prevents brightness inconsistency due to the adhesion of a light guide plate by having a rugged structure formed on an outermost layer that is a surface used for reflection without application of a particulate coating layer.SOLUTION: A reflector which has a resin layer (A) with a surface average roughness (Sa) of three-dimensional surface roughness being 0.90 μm or more, not a coating layer having a rugged structure formed by organic or inorganic spherical particulates, is proposed on an outermost layer that is a surface used for reflection. Further, a reflector is proposed, where the resin layer (A) is preferably constituted by a mixture of two or more thermoplastic resins having an absolute value of the difference between solubility parameters (SP values), which is 0.3-3.0 (cal/cm).

Description

  The present invention relates to a reflective material that can be suitably used as a constituent member of a liquid crystal display, a lighting fixture, or a lighting signboard.

  Reflective materials are used in many fields such as liquid crystal displays, lighting fixtures or lighting signs. Recently, in the field of liquid crystal displays, the size of the device and the advancement of display performance have advanced, and it has become necessary to improve the performance of the backlight unit by supplying as much light as possible to the liquid crystal. However, even more excellent light reflectivity (also simply referred to as “reflectivity”) has been demanded.

As a reflective material, for example, a reflective film for a liquid crystal display using a white polyester film mainly composed of an aromatic polyester resin is known (see Patent Document 1).
However, when an aromatic polyester-based resin is used as a material for the reflector, the aromatic ring contained in the molecular chain of the aromatic polyester-based resin absorbs ultraviolet rays, and therefore, by ultraviolet rays emitted from a light source such as a liquid crystal display device, There was a problem that the film deteriorated and yellowed, and the light reflectivity of the reflective film was lowered.

Further, by stretching a film formed by adding a filler to a polypropylene resin, a fine void is formed in the film, and light scattering reflection is caused (refer to Patent Document 2), olefin-based An olefin-based resin light reflector having a laminated structure including a base material layer containing a resin and a filler and a layer containing an olefin-based resin is also known (see Patent Document 3).
A reflective film using such an olefin resin has a feature that there are few problems of film deterioration and yellowing due to ultraviolet rays.

Furthermore, as a reflective sheet made of a resin composition not containing a large amount of inorganic powder, biaxial stretching with reduced heat shrinkage, comprising at least one of a polypropylene resin and a resin incompatible with the polypropylene resin A reflection sheet is known (see Patent Document 4).
This reflection sheet has a feature that it exhibits higher reflectance than a conventional reflection sheet having the same basis weight and density even if it does not contain a large amount of inorganic powder.

On the other hand, the reflection sheet described above generally has a relatively smooth surface and strong regular reflection. Therefore, when the light source is turned on after being incorporated in a liquid crystal display, the brightness of the screen is uneven (so-called luminance unevenness). There was a problem.
Accordingly, in order to solve the problem of luminance unevenness on the screen, a reflection sheet having high light diffusibility by coating the surface with organic fine particles to form irregularities has been proposed (see Patent Document 5).

Japanese Patent Laid-Open No. 04-239540 JP-A-11-174213 JP 2005-031653 A JP 2008-158134 A JP 2010-085843 A

Another problem that arises from the smooth surface of the reflective sheet is that when the light guide plate is deformed by load or heat, a portion that is in intimate contact with the reflective sheet occurs, and that portion exhibits excessive brightness, The phenomenon that appears as uneven brightness of spots or spots is particularly regarded as a problem (sometimes commonly referred to as white spots. Hereinafter, in this specification, such phenomenon will be simplified as “uneven brightness unevenness of light guide plate”. ").
It is assumed that this light guide plate contact luminance unevenness is likely to occur, particularly when the metal back chassis behind the reflective sheet has a concavo-convex structure, because strong contact occurs at the contact portion between the concavo-convex and the reflective material. FIG. 1 illustrates a conceptual diagram of a mechanism for generating unevenness of light guide plate contact luminance.

As a method for dealing with unevenness in the light guide plate contact luminance, it is common to form irregularities by applying a fine particle coating (coating) layer on the surface of a reflector.
By forming such a coating layer, when an external force such as pressure and heat is applied toward the pressure bonding of the light guide plate, the fine particles forming the concavo-convex structure do not collapse and prevent strong adhesion between the light guide plate and the reflective material. For this reason, it is considered to be effective for preventing unevenness in the light guide plate contact luminance.

  In this case, the higher the hardness of the fine particles, the more difficult it is to be crushed and effective in preventing unevenness of the light guide plate adhesion luminance. However, if the hardness is too high, when the friction causes friction between the reflector and the light guide plate, the light guide plate This causes a problem that the dots are scraped off by fine particles.

  In addition, applying a fine particle coating layer to the reflective material leads to an increase in the number of processes and an increase in cost, and it is a great advantage if a concavo-convex structure can be formed on the surface without a special process such as coating. Become.

  Accordingly, an object of the present invention is to provide a reflective material effective in preventing unevenness of brightness due to adhesion of a light guide plate by forming a concavo-convex structure on the outermost layer, which is a reflective use surface, without applying a fine particle coating layer to the reflective material There is.

The present inventor formed a fine particle coat layer on the outermost layer, which is a reflection use surface, by a reflective material having a resin layer (A) having a specific surface roughness without forming a fine particle coat layer on the reflective material. As in the case, the present inventors have found that the effect of preventing uneven brightness due to the close contact of the light guide plate can be achieved, and the present invention has been solved.
That is, the present invention is not a coating layer having a concavo-convex structure formed by organic or inorganic spherical fine particles on the outermost layer which is a reflection use surface, but has a surface average roughness (Sa) of three-dimensional surface roughness. The present invention proposes a reflecting material having a resin layer (A) of 0.90 μm or more.

The reflective material proposed by the present invention has a resin layer (A) having a specific surface roughness (surface average roughness Sa) on the outermost layer which is a reflection use surface, and the resin layer (A) is a light guide plate. This prevents the occurrence of luminance unevenness by preventing the adhesion.
Therefore, this reflective material can be suitably used as a reflective material for liquid crystal displays, lighting fixtures, or lighting signs.

FIG. 1 is a conceptual diagram of a mechanism for generating unevenness of light guide plate contact luminance.

  Hereinafter, a reflective material (referred to as “the present reflective material”) as an example of an embodiment of the present invention will be described. However, the present invention is not limited to this reflector.

<This reflective material>
This reflective material is a reflective material which has the resin layer (A) whose surface average roughness (Sa) of three-dimensional surface roughness is 0.9 micrometer or more. This resin layer (A) has a significant feature that it is not formed by a coating layer having a concavo-convex structure formed by organic or inorganic spherical fine particles.

“Coating layer having a concavo-convex structure formed of organic or inorganic spherical fine particles” means a layer having a concavo-convex structure formed by exposing a part or all of spherical fine particles from the coating surface of a binder. Say.

<Resin layer (A)>
The resin layer (A) is located in the outermost layer, which is a reflection use surface, and is not a coating layer having a concavo-convex structure formed by organic or inorganic spherical fine particles, but a surface average in three-dimensional surface roughness. This layer has a concavo-convex structure with a roughness (Sa) of 0.9 μm or more, and plays a role of preventing the occurrence of uneven brightness of the light guide plate. In addition, as long as it becomes such surface average roughness (Sa), the constituent material of a resin layer (A) will not be restrict | limited in particular, Various thermoplastic resins etc. can be used.

(Surface roughness)
It is important that the surface average roughness (Sa) of the three-dimensional surface roughness of the surface of the resin layer (A) is 0.9 μm or more from the viewpoint of preventing unevenness in the light guide plate adhesion luminance.
Furthermore, it is preferable if the thickness is 1.2 μm or more because unevenness in the light guide plate contact luminance can be better prevented. The surface average roughness (Sa) of the three-dimensional surface roughness is a value measured according to the description of the examples described below.

  As a method for forming the resin layer (A) having the above-mentioned surface average roughness (Sa) and having an uneven structure, (1) a method by embossing, (2) a method by press transfer, and (3) two or more types Among these methods, the method (3) is most preferably used to form the resin layer (A).

(Method by embossing)
(1) As a method of embossing, for example, a heated and melted resin is extruded from a T die to a pair of pressure rolls, one of which is a roll provided with embossed eyes and the other is a roll provided with an elastic body on the surface. , A method of forming a film having embossed eyes, a method of applying embossed eyes to the film by pressurizing the film between a hot press machine and an embossing shaping mold, one roll provided with embossed eyes, and the other For example, a method of giving embossed eyes to the film by passing the film through a pair of heating and pressurizing rolls composed of heating rolls while heating and pressurizing. In the case of embossing, it is advantageous in that an arbitrary roughness can be selected from several microns to several millimeters depending on the design of the embossing. However, it is not the meaning limited to these.

(Method by press transfer)
(2) As a method by press transfer, for example, a fine uneven pattern is intermittently press-formed on the surface of a sheet material wound in a roll shape, thereby transferring and shaping the fine shape pattern on the surface of the sheet material. The method of letting you do is mentioned.
However, although it is possible to shape any roughness by designing the fine shape pattern of the mold, in the case of processing a large size or wide sheet, it takes a lot of time for heating and cooling, and one cycle time is remarkably long. There is a concern that it will become long and productivity will deteriorate.

(Method by mixing two or more thermoplastic resins)
(3) When the resin layer (A) having a desired surface average roughness (Sa) is formed by mixing two or more thermoplastic resins, the thermoplastic resin (I) and the resin layer (A) are incompatible with the resin layer (A). As the thermoplastic resin (II), attention is paid to the solubility parameter (hereinafter referred to as “SP value”) of the two kinds of resins to be mixed, the absolute value of the difference in apparent viscosity, or both.
About SP value, the absolute value of the difference of SP value is 0.3-3.0 (cal / cm < ³ >) ^0.5 , More preferably, it is 0.5-1.5 (cal / cm < ³ >) ^0.5 . What is necessary is just to select such a combination.
By adjusting to such a range, the dispersibility of the two kinds of resins is appropriately adjusted, and the surface average roughness (Sa) in the three-dimensional surface roughness of the resin layer (A) to be formed is the above value. can do. If the absolute value of the difference in SP value of the resin to be mixed is 0.5 (cal / cm ³ ) ^0.5 or more, dispersion of the incompatible thermoplastic resin (II) in the resin layer (A) Since a phase is formed and the surface of the resin layer (A) becomes rough, it is preferable.
On the other hand, if the absolute value of the difference in SP value of the resin to be mixed is 3.0 (cal / cm ³ ) ^0.5 or less, the incompatible thermoplastic resin (II) in the resin layer (A) It is preferable because the dispersed phase is stably formed and the film forming property of the resin layer (B) is also stable.

As for the apparent viscosity (η), the absolute value of the difference in melt viscosity (value at shear rate: 100 (1 / sec)) at the extrusion processing temperature is preferably 1000 (Pa · s) or less.
Moreover, it is preferable to make the difference in apparent viscosity smaller as the difference in SP value between the two selected thermoplastic resins is smaller. By adjusting the apparent viscosity (η) to a certain value or less, the dispersion diameter of the incompatible resin is refined, and the surface average roughness (Sa) of the formed resin layer (A) may be 0.9 or less. it can.

(Surface unevenness technology using SP value difference of incompatible resin)
First, with respect to a method by mixing two or more thermoplastic resins, a concavo-convex structure having a desired surface average roughness (Sa) is formed by setting the absolute value of the difference in solubility parameter (SP value) within a certain range. The method of performing will be described in detail below.

More specifically, the SP value of one of the thermoplastic resins (I) is preferably 5.0 to 15.0 (cal / cm ³ ) ^0.5 , more preferably 7.0 (cal / cm ³ ). ^It is more preferable that it is ^0.5 or more or 12.0 (cal / cm ³ ) ^0.5 or less.
The other thermoplastic resin (II) has an SP value of preferably 5.3 to 14.7 (cal / cm ³ ) ^0.5 , and more preferably 7.3 (cal / cm ³ ) ^0.5 or more. Or it is more preferable that it is 11.7 (cal / cm < ³ >) ^0.5 or less.

  From such a technical idea, a thermoplastic resin (I) having an SP value in the above range is screened as a candidate resin 1, and further, a thermoplastic resin incompatible with the thermoplastic resin (I) having an SP value in the above range. Resin (II) is screened as candidate resin 2 and the surface average roughness (Sa) in the three-dimensional surface roughness is 0.5 or more from the resin layer formed by the combination of these candidate resins 1 and 2. By selecting what becomes, a resin layer (A) can be formed.

In addition, SP value is the following Fedors equation, the evaporation energy (Δei) and molar volume (Δvi) of the atoms and atomic groups constituting the thermoplastic resin (I) or the incompatible thermoplastic resin (II). It can be obtained by substitution.
SP value (cal / cm ³ ) ^0.5 = (ΣΔei / ΣΔvi) ^0.5
Here, constants proposed by Fedors were used for Δei and Δvi (see Table 1). Table 1 is an excerpt of the evaporation energy and molar volume of atoms and groups by Fedors.

In the resin layer (A), the thermoplastic resin (I) and the incompatible thermoplastic resin (II) may each be one type of resin or two or more types of resins. For example, one type of thermoplastic resin (I-1) and two types of incompatible thermoplastic resins (II-1) and (II-2) may be included.
Further, in addition to the thermoplastic resin (I-1) and the thermoplastic resin (II-1) incompatible therewith, the thermoplastic resin (I-2) and the thermoplastic resin incompatible with the thermoplastic resin (I-2). Two or more kinds of combinations such as resin (II-2) may be included.
Thermoplastic resin (in the sea-island structure formed of thermoplastic resin (I-1) and incompatible thermoplastic resin (II-1), there are a plurality of island phases or a plurality of sea phases. In this case, the absolute value of the difference between the maximum SP values of the sea phase and the island phase may be obtained.

Further, from the viewpoint of the effect of making the surface average roughness (Sa) of the surface of the resin layer (A) 0.5 μm or more, the thermoplastic resin (I) and the thermoplastic resin (II) incompatible with this, In other words, the amount of resin contained in the combination in which the absolute value of the SP value difference is 0.3 to 3.0 (cal / cm ³ ) ^0.5 is 70 mass of the total resin constituting the resin layer (A). % Or more, preferably 80% by mass or more, and preferably 90% by mass or more.

The content ratio of the thermoplastic resin (I) and the thermoplastic resin (II) incompatible with the thermoplastic resin (I) is 60:40 to 90:10, or 40:60 to 10:90, particularly 70: Those having a ratio of 30 to 80:20 or 30:70 to 20:80 are preferable from the viewpoint of the effect that the dispersed phase is stably formed and the surface of the resin layer (A) is roughened.
However, the surface of the resin layer (A) is roughened because it is the difference between which one of the thermoplastic resin (I) and the thermoplastic resin (II) increases, either of which becomes a matrix phase or a dispersed phase. The same is true in terms of the effects to be realized.

(Surface unevenness technology using difference in melt viscosity of incompatible resin)
Next, regarding the method by mixing two or more kinds of thermoplastic resins, by setting the absolute value of the difference in apparent viscosity (shear rate: 100 (1 / sec)) at the extrusion processing temperature within a certain range, a desired surface is obtained. A method for forming a concavo-convex structure having an average roughness (Sa) will be described in detail below.

In general, in the mixed system of the thermoplastic resin (I) and the thermoplastic resin (II) incompatible therewith, the smaller the absolute value of the difference in apparent viscosity between the resins, the smaller the dispersion diameter. It is presumed that this leads to an increase in fine irregularities and an increase in surface roughness.
Therefore, it is considered that the absolute value of the difference in apparent viscosity contributes to the expression of the surface roughness in the mixed system together with the absolute value of the difference in SP value described above.
Therefore, it is more preferable to adjust the apparent viscosity according to the SP value difference between the resins used. Specifically, the larger the SP value difference between the resins, the larger the absolute value of the apparent viscosity difference may be, and the smaller the SP value difference between the resins used, the smaller the absolute value of the apparent viscosity difference. It is preferable.
For example, the absolute value of the difference between the SP values, as in the examples described later, ie, a combination of COP (SP value: 7.4) and PP (SP value: 8.0) (SP value difference: 0.6). Is 0.6 or more and less than 1.4, the apparent viscosity (η) of the sea phase and the island phase (shear rate: 100) at the extrusion temperature (230 ° C.) in the formed sea-island structure. The absolute value of the difference (value in (1 / sec)) is preferably 1200 (Pa · s) or less, and more preferably 1000 (Pa · s) or less.
In the sea-island structure formed of a thermoplastic resin (thermoplastic resin (I-1) and incompatible thermoplastic resin (II-1), a plurality of island phases or a plurality of sea phases When it exists, it is preferable that the absolute value of the difference of each of a plurality of sea phases and island phases is in the above range.

(Additional properties)
As a kind of resin constituting the resin layer (A), preferably a kind of base resin, for example, thermoplastic resin (I) or (II), the glass transition temperature (JIS K-7121, Tg) is 85 to 150 ° C. Heat resistance can also be imparted to the reflective material by using an amorphous resin.
The base resin of the resin layer (A) means a resin that occupies 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more with respect to the total mass of the resin layer (A). It is.

As used herein, an amorphous resin refers to a resin having an extremely low crystallinity in which an exothermic peak accompanying crystallization is not observed, or even if it is observed, the heat of crystal fusion is 10 J / g or less.
Amorphous resin exhibits stable characteristics below the glass transition point even when the ambient temperature changes, and is highly reflective material because of its low shrinkage and excellent dimensional stability up to temperatures near the glass transition point. Heat resistance can be imparted.

Therefore, if the base resin of the resin layer (A), for example, the glass transition temperature (Tg) of the thermoplastic resin (I) is 85 to 150 ° C., the heat resistance is sufficient even when used as a constituent member of a liquid crystal display or the like. Yes, it is preferable.
From this viewpoint, the glass transition temperature (Tg) of the base resin of the resin layer (A) is more preferably 90 ° C. or higher and 150 ° C. or lower, and more preferably 100 ° C. or higher and 150 ° C. or lower. .

Examples of this type of amorphous resin include cycloolefin resin, polystyrene, polycarbonate, acrylic resin, amorphous polyester resin, polyetherimide, and thermoplastic polyimide.
Among these, in view of stretchability, glass transition temperature range, and transparency, cycloolefin resins, polystyrene, and polycarbonate resins are preferable, and among them, cycloolefin resins are particularly preferable.

Here, the cycloolefin resin of the resin layer (A) may be either a cycloolefin homopolymer or a cycloolefin copolymer.
The cycloolefin-based resin is a polymer compound having a main chain composed of a carbon-carbon bond and having a cyclic hydrocarbon structure in at least a part of the main chain. This cyclic hydrocarbon structure is introduced by using a compound (cycloolefin) having at least one olefinic double bond in the cyclic hydrocarbon structure as represented by norbornene or tetracyclododecene as a monomer. Is done.

  Cycloolefin-based resins include cycloolefin addition (co) polymers or hydrogenated products thereof, cycloolefin and α-olefin addition copolymers or hydrogenated products thereof, cycloolefin ring-opening (co) polymers or the like. They are classified as hydrogenated substances, and any of them can be used for the present reflective material.

  Specific examples of the cycloolefin resin include cyclopentene, cyclohexene, cyclooctene; monocyclic cycloolefins such as cyclopentadiene and 1,3-cyclohexadiene; bicyclo [2.2.1] hept-2-ene (common name) : Norbornene), 5-methylbicyclo [2.2.1] hept-2-ene, 5,5-dimethyl-bicyclo [2.2.1] hept-2-ene, 5-ethyl-bicyclo [2.2 .1] Hept-2-ene, 5-butyl-bicyclo [2.2.1] hept-2-ene, 5-ethylidene-bicyclo [2.2.1] hept-2-ene, 5-hexyl-bicyclo [2.2.1] hept-2-ene, 5-octyl-bicyclo [2.2.1] hept-2-ene, 5-octadecyl-bicyclo [2.2.1] hept-2-ene, 5 −Me Riden-bicyclo [2.2.1] hept-2-ene, 5-vinyl-bicyclo [2.2.1] hept-2-ene, 5-propenyl-bicyclo [2.2.1] hept-2- Bicyclic cycloolefins such as ene;

  Tricyclo [4.3.0.12,5] deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.12,5] dec-3-ene; tricyclo [4. 4.0.12,5] undeca-3,7-diene or tricyclo [4.4.0.12,5] undeca-3,8-diene or partial hydrogenates thereof (or addition of cyclopentadiene and cyclohexene) Tricyclo [4.4.0.12,5] undec-3-ene; 5-cyclopentyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexylbicyclo [2.2.1] ] Tricyclic cycloolefins such as hepta-2-ene, 5-cyclohexenylbicyclo [2.2.1] hept-2-ene, 5-phenyl-bicyclo [2.2.1] hept-2-ene;

  Tetracyclo [4.4.0.12,5.17,10] dodec-3-ene (also simply referred to as tetracyclododecene), 8-methyltetracyclo [4.4.0.12,5.17,10 ] Dodec-3-ene, 8-ethyltetracyclo [4.4.0.12, 5.17,10] dodec-3-ene, 8-methylidenetetracyclo [4.4.0.12,5. 17,10] dodec-3-ene, 8-ethylidenetetracyclo [4.4.0.12,5.17,10] dodec-3-ene, 8-vinyltetracyclo [4,4.0.12. 5.17,10] Dodeca-3-ene, a 4-ring cycloolefin such as 8-propenyl-tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene;

8-cyclopentyl-tetracyclo [4.4.0.12,5.17,10] dodec-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.12,5.17,10] dodec-3-. Ene, 8-cyclohexenyl-tetracyclo [4.4.0.12,5.17,10] dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.12,5.17,10 Dodeca-3-ene; tetracyclo [7.4.13, 6.01, 9.02, 7] tetradeca-4,9,11,13-tetraene (1,4-methano-1,4,4a, 9a -Tetrahydrofluorene), tetracyclo [8.4.14,7.01,0.03,8] pentadeca-5,10,12,14-tetraene (1,4-methano 1,4,4a, 5, 10, 10a Hexahydroanthracene); pentacyclo [6.6.1.13, 6.02, 7.09, 14] -4-hexadecene, pentacyclo [6.5.1.13, 6.02, 7.09 , 13] -4-pentadecene, pentacyclo [7.4.0.02,7.13,6.110,13] -4-pentadecene; heptacyclo [8.7.0.12,9.14,7.111. , 17.03, 8.012, 16] -5-eicosene, heptacyclo [8.7.0.12, 9.03, 8.14, 7.012, 17.113, 16] -14-eicosene; cyclo And polycyclic cycloolefins such as pentadiene tetramer.
These cycloolefins can be used alone or in combination of two or more.

Specific examples of the α-olefin copolymerizable with cycloolefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3 -Ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl 1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1- 2-20 carbon atoms such as xene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, preferably 2 carbon atoms 8 ethylene or α-olefin.
These α-olefins can be used alone or in combination of two or more.

  There are no particular limitations on the polymerization method of cycloolefin or cycloolefin and α-olefin, and the hydrogenation method of the obtained polymer, and it can be carried out according to a known method.

Among the cycloolefin resins described above, from the viewpoint of heat resistance, cycloolefin resins having a glass transition temperature (Tg) of 70 to 170 ° C., particularly 80 ° C. or more and 160 ° C. or less, particularly 85 ° C. or more and 150 ° C. or less. preferable.
At this time, two or more types of cycloolefin resins may be combined and mixed, and the glass transition temperature (Tg) of the mixed resin may be adjusted to the above range.

  Commercial products can be used as the cycloolefin resin. For example, “ZEONOR (registered trademark)” manufactured by Nippon Zeon Co., Ltd. (chemical name: hydrogenated product of a ring-opening polymer of cyclic olefin), “APEL®” (ethylene and tetracyclododecene) manufactured by Mitsui Chemicals, Inc. And "TOPAS (registered trademark)" (addition copolymer of ethylene and norbornene) manufactured by Polyplastics. Among them, “ZEONOR (registered trademark)” manufactured by ZEON CORPORATION (chemical name: hydrogenated product of a ring-opening polymer of cyclic olefin) and / or “TOPAS®” (ethylene manufactured by Polyplastics Co., Ltd.) And a norbornene addition copolymer) are particularly preferable because a reflective material having high reflection performance can be obtained.

  In addition, when using the copolymer of an olefin and norbornene as a cycloolefin, it is preferable that content of norbornene is 60-90 wt%, and it is especially preferable that it is 65 to 80 wt%.

  The above amorphous resin (when two or more amorphous resins are included, the total amount thereof) is preferably 50% by mass or more based on the total mass of the resin layer (A). More preferably, it is 70% by mass or more, and particularly preferably 90% by mass or more (excluding 100%).

  As described above, when an amorphous resin having a glass transition temperature of 85 to 150 ° C. is used as the base resin of the resin layer (A), for example, the thermoplastic resin (I), the viewpoint of improving the bending resistance is taken into consideration. Then, it is preferable to contain an olefin resin, a thermoplastic elastomer, etc. as other resin, for example as thermoplastic resin (II).

  For example, by forming a resin layer (A) by blending a cycloolefin resin with an olefin resin other than a cycloolefin resin and / or a thermoplastic elastomer, a folding resistance that cannot be obtained with a cycloolefin resin alone. Both the curvature and the heat resistance that cannot be obtained with the olefin resin alone can be ensured.

At this time, the melt flow rate (referred to as “MFR”) of the olefin resin and / or thermoplastic elastomer other than the cycloolefin resin is 0.1 or more, or 20 or less (JIS K-7210, 230 ° C., load 21). .18N), more preferably 0.5 or more, or 10 or less.
Moreover, it is preferable to adjust MFR of cycloolefin resin to the said range. Thus, when both MFRs are adjusted, olefin-based resins other than cycloolefin-based resins and / or thermoplastic elastomers are oriented in the cycloolefin-based resin, and the mechanical properties as a reflector are extremely deteriorated. Since there is no fear, it is particularly preferable.

Examples of olefin resins other than cycloolefin resins include polypropylene resins such as polypropylene and propylene-ethylene copolymers, and polyethylene resins such as polyethylene, high-density polyethylene, and low-density polyethylene. One or two or more of them can be used in combination. Among them, polyethylene resin (PE) and polypropylene resin (PP) are preferable, and polypropylene resin (PP) is particularly preferable from the viewpoint of having a high melting point and excellent heat resistance as compared with polyethylene resin and high mechanical properties such as elastic modulus. Resins are preferred.
Further, from the viewpoint of extrusion moldability, among polypropylene resins, a polypropylene resin having an MFR (230 ° C., 21.18N) of 0.1 to 20, particularly 0.2 to 10, and particularly 0.5 to 5 is particularly preferable. preferable.

  On the other hand, examples of the thermoplastic elastomer include olefin-based elastomers, styrene-based elastomers, urethane-based elastomers, polyester-based elastomers, and the like, and one or more of these can be used in combination. Among them, the styrene elastomer is preferable from the viewpoint of improving the adhesion between the resin layer (A) and the resin layer (B) because it is compatible with an olefin resin, particularly a polypropylene resin.

Examples of the styrene-based elastomer include a copolymer of styrene and a conjugated diene such as butadiene or isoprene, and / or a hydrogenated product thereof. Styrenic elastomers are preferred because they are block copolymers having styrene as a hard segment and conjugated diene as a soft segment and do not require a vulcanization step. A hydrogenated product is more preferable because of high thermal stability.
Preferred examples of the styrene elastomer include, for example, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-ethylene-butylene-styrene block copolymer, and a styrene-ethylene-propylene-styrene block. Mention may be made of copolymers.
In particular, styrene-ethylene-butylene-styrene block copolymers and styrene-ethylene-propylene-styrene block copolymers (also referred to as hydrogenated styrene elastomers) in which the double bond of the conjugated diene component has been eliminated by hydrogenation. .) Is preferred.

(Fine powder filler)
The resin layer (A) may contain a fine powder filler. About the kind of fine powder filler, a particle size, and the surface treatment method, it is the same as that of the content demonstrated by the resin layer (B) mentioned below, and its preferable example is also the same.

(Form of resin layer (A))
The resin layer (A) may be a layer composed of a sheet body, or may be a layer formed by forming a thin film (without forming a sheet) by extrusion or coating of the molten resin composition. . In the case of a sheet body, the sheet body may be an unstretched film or a uniaxial or biaxially stretched film, but a stretched film obtained by stretching at least 1.1 times in a uniaxial direction, A biaxially stretched film is particularly preferable.

(Other ingredients)
The resin layer (A) may contain an antioxidant, a light stabilizer, a heat stabilizer, an ultraviolet absorber, a fluorescent brightener, a lubricant, a light diffusing material, and other additives.
Note that a compatibilizing agent, a dispersing agent, and the like can be blended in a small amount.

<Resin layer (B)>
The resin layer (B) is a layer having voids inside, preferably a layer that can impart high reflectivity to the reflective material, and more preferably can improve the bending resistance of the reflective material.

(Porosity of resin layer (B))
A resin layer (B) is a layer which has a space | gap inside, and it is preferable that the porosity, ie, the volume ratio which a space | gap occupies for the said layer, is 10 to 90% from a viewpoint of ensuring reflectivity.
By providing the voids in such a range, the whitening of the reflective material proceeds sufficiently, so that high reflectivity can be achieved, and the mechanical strength of the reflective material is reduced and does not break.
From such a viewpoint, the porosity of the resin layer (B) is 20% or more or 80% or less, particularly 25% or 75% or less, particularly 30% or 70% or less, among the above range. Is preferred.

Examples of the method for forming voids in the resin layer (B) include a chemical foaming method, a physical foaming method, a supercritical foaming method, a stretching method, and an extraction method. Among these, in the present reflective material, the stretching method is preferable from the viewpoints of film forming properties, continuous productivity, stable productivity, and the like.
Specific examples of the stretching method include a roll stretching method, a rolling method, a tenter stretching method, and the like. Among these, the roll stretching method and / or the tenter stretching method in the present invention has a wide selection range of stretching conditions, and therefore a method of stretching them in at least one direction alone or in combination is preferably used.
The stretching may be performed by a uniaxial stretching method that stretches in the machine direction (MD) by a roll stretching method or the like, a sequential biaxial stretching method that stretches in the transverse direction (TD) by a tenter stretching method after uniaxial stretching in the longitudinal direction, or a tenter. Examples thereof include a simultaneous biaxial stretching method in which stretching is performed simultaneously in the longitudinal direction and the transverse direction using a stretching method. Note that biaxial stretching is preferred from the viewpoint of enhancing reflectivity.

(Base resin)
Examples of the resin (base resin) constituting the main component of the resin layer (B) include olefin resins, polyester resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, and polyethers. Resin, polyamide resin, polyurethane resin, diene resin and the like. Among these, an olefin resin is preferable from the viewpoint of enhancing reflectivity.

Examples of the olefin resin include polypropylene resins such as polypropylene and propylene-ethylene copolymers, polyethylene resins such as polyethylene, high density polyethylene, and low density polyethylene, and cycloolefin resins such as ethylene-cyclic olefin copolymers. There may be mentioned at least one polyolefin resin selected from (including the above-mentioned cycloolefin-based resin).
Among these, polypropylene resin (PP) and polyethylene resin (PE) are preferable from the viewpoint of mechanical properties, flexibility, etc. Among them, in particular, melting point is higher and heat resistance is higher than PE, and elastic modulus etc. From the viewpoint of high mechanical properties, polypropylene resin (PP) is preferable.
In addition, from the viewpoint of extrusion moldability, among polypropylene resins (PP), MFR (230 ° C. 21.18N) is 0.1 to 20, particularly 0.2 to 10, particularly 0.5 to 5. (PP) is particularly preferred.

  The base resin contained in the resin layer (B) is preferably 30% by mass or more, more preferably 40% by mass or more, and particularly preferably 50% by mass with respect to the total mass of the resin layer (B). It is at least mass% (including 100%).

(Fine powder filler)
The resin layer (B) preferably contains a fine powder filler in order to obtain excellent reflectivity. By containing the fine powder filler, in addition to the refractive scattering due to the refractive index difference between the base resin and the fine powder filler, the refractive scattering due to the refractive index difference with the cavity formed around the fine powder filler, and further fine powder Reflectivity can also be obtained from refraction scattering due to the difference in refractive index between the cavity formed around the filler and the fine filler.

Examples of the fine powder filler include inorganic fine powder and organic fine powder.
Inorganic fine powders include calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, zinc oxide, alumina, aluminum hydroxide, hydroxyapatite, silica, Examples include mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay. Any of these may be used alone or in admixture of two or more. Among these, considering the difference in refractive index with the resin constituting the sheet, those having a large refractive index are preferable, and calcium carbonate, barium sulfate, titanium oxide or zinc oxide having a refractive index of 1.6 or more is used. Is particularly preferred.

In addition, titanium oxide has a significantly higher refractive index than other inorganic fillers and can significantly increase the difference in refractive index from the base resin, so it is less blended than when other fillers are used. Excellent reflectivity can be obtained in an amount. Furthermore, by using titanium oxide, high reflectivity can be obtained even if the thickness of the reflector is reduced.
Therefore, it is more preferable to use a filler containing at least titanium oxide. In this case, the amount of titanium oxide is 30% or more of the total mass of the inorganic filler, or a combination of an organic filler and an inorganic filler. In such a case, the total mass is preferably 30% or more.
Further, in order to improve the dispersibility of the inorganic fine powder in the resin, the surface of the fine powder filler was subjected to a surface treatment with a silicon compound, a polyhydric alcohol compound, an amine compound, a fatty acid, a fatty acid ester, or the like. Things may be used.

  On the other hand, examples of the organic fine powder include polymer beads and polymer hollow particles, which can be used alone or in combination of two or more. Moreover, you may use combining inorganic fine powder and organic fine powder.

  The fine powder filler preferably has a particle size of 0.05 μm or more and 15 μm or less, more preferably 0.1 μm or more and 10 μm or less. If the particle size of the filler is 0.05 μm or more, the dispersibility in the base resin does not decrease, and a homogeneous sheet can be obtained. If the particle size is 15 μm or less, the interface between the base resin and the fine powder filler is densely formed, and a highly reflective reflector is obtained.

Further, the content of the fine powder filler is 10 to 80% by mass with respect to the total mass of the resin layer (B) in consideration of the reflectivity, mechanical strength, productivity and the like of the reflector. It is preferably 20 to 70% by mass.
When the content of the fine powder filler is 20% by mass or more, the area of the interface between the base resin and the fine powder filler can be sufficiently secured, and high reflectivity can be imparted to the reflector. When the content of the fine powder filler is 70% by mass or less, the mechanical strength necessary for the reflector can be ensured.

  In the resin layer (B), the content ratio of the base resin and the fine powder filler is, from the viewpoint of light reflectivity, mechanical strength, productivity, and the like, base resin: fine powder filler = 80: 20 to 30:70. In particular, 80:20 to 60:40 is preferable.

(Other ingredients)
The resin layer (B) may contain other resins than those described above. Moreover, you may contain antioxidant, a light stabilizer, a heat stabilizer, a dispersing agent, a ultraviolet absorber, a fluorescent whitening agent, a compatibilizer, a lubricant, and other additives.

(Form of resin layer (B))
The resin layer (B) may be a layer formed of a sheet body, or may be a layer formed by forming a thin film of the molten resin composition by extrusion or coating (without forming a sheet). . In the case of a sheet body, the sheet body may be an unstretched film, a uniaxial or biaxially stretched film, but a stretched film obtained by stretching at least 1.1 times in a uniaxial direction, particularly two An axially stretched film is preferred.

<Laminated structure>
The reflective material preferably has a laminated structure in which a resin layer (A) and a resin layer (B) are provided.
By adopting such a configuration, while imparting reflectivity to the resin layer (B), it retains workability such as bending resistance, and prevents unevenness in brightness due to adhesion of the light guide plate to the resin layer (A). Can be granted.
Thus, this reflective material can exhibit a synergistic effect by interaction of resin layer (A) and (B), and can show very superior reflectivity.

  Further, by selecting the resin of the resin layer (A), it is possible to impart heat resistance, and there are advantages such as imparting heat resistance and workability while exhibiting higher reflectivity. is there.

  Furthermore, in such a laminated structure, the resin layer (A) is located in the outermost layer on the light irradiation side (reflection use surface side). By setting it as such a structure, high reflectivity can be provided to a reflecting material.

  Moreover, as another laminated structure, the laminated structure of 3 layers which provided the resin layer (A) on both surfaces of the resin layer (B) can be mentioned, for example. Furthermore, in addition to the resin layer (A) and the resin layer (B), other layers may be provided, and other layers may be interposed between the resin layer (A) and the resin layer (B). For example, an adhesive layer may be interposed between the resin layer (A) and the resin layer (B).

<Thickness>
The thickness of the reflective material is not particularly limited, and is preferably, for example, 30 μm to 1500 μm, and particularly preferably about 50 μm to 1000 μm in consideration of handleability in practical use.
For example, the thickness of the reflective material for liquid crystal display is preferably 50 μm to 700 μm. For example, the thickness of the reflective material for lighting fixtures and lighting signboards is preferably 100 μm to 1000 μm.

Even if the resin layer (A) is thin, the heat resistance of the entire reflecting material can be increased. On the other hand, if the resin layer (A) is too thick, the bending resistance is lowered.
From such a viewpoint, the total thickness ratio of each layer of the resin layer (A) and the resin layer (B) (for example, the ratio of the total thickness of the two layers when there are two resin layers (B)) is 1: 3. The ratio is preferably 1:15, more preferably 1: 3 to 1:10.

<Average reflectance>
The reflective material preferably has an average reflectance of at least one surface of 97% or more with respect to light having a wavelength of 420 nm to 700 nm. If it has such reflectivity, it exhibits good reflection characteristics as a reflective material, and a liquid crystal display or the like incorporating this reflective material can realize a sufficient brightness of the screen.

<Porosity>
The reflective material preferably includes a resin layer (B) layer having voids in order to enhance reflectivity. However, the porosity of the resin layer (B), that is, the void rate when voids are formed by stretching. Can be obtained by the following equation for the film constituting the resin layer (B).
Porosity (%) = {(density of film before stretching−density of film after stretching) / density of film before stretching} × 100

<Manufacturing method>
The method for producing the reflective material is not particularly limited, and a known method can be adopted. Below, although an example is given and demonstrated about the manufacturing method of the reflecting material provided with the laminated structure, it is not limited to the following manufacturing method at all.

First, a resin composition A is prepared by blending an amorphous resin such as a cycloolefin resin with an olefin resin and / or a thermoplastic elastomer and other additives as necessary.
Specifically, the olefin resin and / or thermoplastic elastomer, other antioxidants and the like are added to the cycloolefin resin as necessary, and mixed with a ribbon blender, tumbler, Henschel mixer, etc., then a Banbury mixer, The resin composition A can be obtained by kneading at a temperature equal to or higher than the melting point of the resin (for example, 220 ° C. to 280 ° C.) using a single screw or twin screw extruder.
Alternatively, the resin composition A can be obtained by adding a predetermined amount of cycloolefin-based resin, olefin-based resin and / or thermoplastic elastomer or the like with a separate feeder or the like.
Also, a so-called master batch in which an olefin resin and / or thermoplastic elastomer and other antioxidants are blended at a high concentration in advance is prepared, and this master batch is combined with a cycloolefin resin, olefin resin and / or heat. A resin composition A having a desired concentration can be obtained by mixing with a plastic elastomer.

On the other hand, the resin composition B which mix | blended the fine powder filler, the other additive, etc. with the olefin resin etc. as needed is produced. Specifically, a fine powder filler or the like is added to the olefin resin as a main component and mixed with a ribbon blender, tumbler, Henschel mixer, etc., and then a Banbury mixer, a single screw or twin screw extruder, etc. The resin composition B can be obtained by kneading at a temperature higher than the melting point of the resin (for example, 190 ° C. to 270 ° C.).
Alternatively, the resin composition B can be obtained by adding a predetermined amount of an olefin resin, a fine powder filler, or the like with a separate feeder or the like.
Also, a resin composition having a desired concentration is prepared by preparing a so-called master batch in which a fine powder filler, other additives, etc. are blended in high concentration with an olefin resin in advance, and mixing this master batch with the olefin resin. B can also be used.

Next, after drying the resin compositions A and B thus obtained, they are supplied to different extruders, respectively, heated to a predetermined temperature or higher and melted.
The conditions such as the extrusion temperature need to be set in consideration of a decrease in molecular weight due to decomposition. For example, the extrusion temperature of the resin composition A is 220 ° C. to 280 ° C., and the resin composition B The extrusion temperature is preferably 190 ° C to 270 ° C.
Thereafter, the melted resin composition A and resin composition B are merged into a T-die for two types and three layers, extruded from a slit-like discharge port of the T-die in a laminated form, and solidified into a cooling roll to form a cast sheet. Form.

The obtained cast sheet is preferably stretched in at least one axial direction.
By extending | stretching, the interface of the olefin resin inside a resin layer (B) and a fine powder filler peels, a space | gap is formed, whitening of a sheet | seat advances, and the light reflectivity of a film can be improved.
Furthermore, the cast sheet is particularly preferably stretched in the biaxial direction. The void formed only by uniaxial stretching has a fibrous form extending in one direction, but by biaxial stretching, the void is elongated in both the vertical and horizontal directions and becomes a disk-shaped form.
That is, by biaxial stretching, the peeling area at the interface between the olefin resin and the fine powder filler inside the resin layer (B) increases, and the whitening of the sheet further progresses. As a result, the light reflectivity of the film Can be further enhanced.
Moreover, since biaxial stretching reduces the anisotropy in the shrinking direction of the film, the heat resistance of the film can be improved, and the mechanical strength of the film can also be increased.

The stretching temperature at the time of stretching the cast sheet is in the range of not less than the glass transition temperature (Tg) of the amorphous resin of the resin layer (A) and not more than (Tg + 50 ° C.) and not more than (Tg + 50 ° C.). It is preferable that the temperature is within the range.
When the stretching temperature is equal to or higher than the glass transition temperature (Tg), the film can be stably formed without breaking during stretching. Further, when the stretching temperature is a temperature of (Tg + 50) ° C. or lower, the stretched orientation becomes high, and as a result, the porosity increases, so that a highly reflective film can be easily obtained.

The stretching order of biaxial stretching is not particularly limited. For example, simultaneous biaxial stretching or sequential stretching may be used. After melt film formation using a stretching facility, the film may be stretched in the film take-up direction (MD) by roll stretching, and then stretched in the MD orthogonal direction (TD) by tenter stretching, or tubular stretching. For example, biaxial stretching may be performed.
In the case of biaxial stretching, the stretching magnification is preferably 6 times or more as the area magnification. By stretching the area magnification by 6 times or more, the porosity of the entire reflection film composed of the resin layer (A) and the resin layer (B) may be 40% or more.

  After stretching, it is preferable to perform heat setting in order to impart dimensional stability (morphological stability of voids) to the reflective film. The treatment temperature for heat-setting the film is preferably 110 ° C to 170 ° C. The processing time required for heat setting is preferably 1 second to 3 minutes. Moreover, there is no limitation in particular about extending | stretching equipment etc., It is preferable to perform the tenter extending | stretching which can perform a heat setting process after extending | stretching.

<Application>
The reflective material can be used as a reflective material as it is, but it can also be used as a structure in which the reflective material is laminated on a metal plate or a resin plate, for example, a liquid crystal display such as a liquid crystal display. It is useful as a reflector used in devices, lighting fixtures, lighting signs, and the like.

  In this case, examples of the metal plate on which the reflective material is laminated include an aluminum plate, a stainless plate, and a galvanized steel plate.

  Examples of the method of laminating the reflective material on a metal plate or resin plate include a method using an adhesive, a method of heat-sealing without using an adhesive, a method of bonding via an adhesive sheet, and extrusion coating. And the like. However, it is not limited to these methods.

More specifically, an adhesive such as polyester, polyurethane, or epoxy is applied to the surface of the metal plate or resin plate (collectively referred to as “metal plate”) to which the reflective material is to be bonded. Can be pasted together.
In such a method, a commonly used coating facility such as a reverse roll coater or a kiss roll coater is used, and the adhesive film thickness after drying is about 2 μm to 4 μm on the surface of a metal plate or the like on which a reflective material is bonded. Apply an adhesive so that
Next, the coated surface is dried and heated with an infrared heater and a hot-air heating furnace, and while maintaining the surface of the metal plate or the like at a predetermined temperature, the reflecting material is immediately coated and cooled using a roll laminator. You can get a board.

The reflective material is useful as a reflective member for use in a liquid crystal display device such as a liquid crystal display, a lighting fixture, and a lighting signboard.
In general, a liquid crystal display includes a liquid crystal panel, a polarizing reflection sheet, a diffusion sheet, a light guide plate, a reflection sheet, a light source, a light source reflector, and the like.
This reflector can also be used as a reflector that plays a role of making light from a light source efficiently enter a liquid crystal panel or a light guide plate, or condenses light emitted from a light source disposed at an edge portion to guide the light guide plate. It can also be used as a light source reflector having a role of being incident on the light source.

<Explanation of terms>
In general, "film" refers to a thin flat product that is extremely small compared to its length and width and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll (Japan) Industrial standard JISK6900), and in general, “sheet” refers to a product that is thin by definition in JIS and generally has a thickness that is small instead of length and width. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

In addition, the expression “main component” in the present specification includes the meaning of allowing other components to be contained within a range that does not hinder the function of the main component unless otherwise specified.
At this time, although the content ratio of the main component is not specified, the main component (when two or more components are main components, the total amount thereof) is 50% by mass or more, preferably 70% in the composition. It occupies at least 90% by mass, particularly preferably at least 90% by mass (including 100%).

In the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” and “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It means “smaller”.
Further, in the present invention, when expressed as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). ) Includes the meaning of “preferably smaller than Y” unless otherwise specified.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention.

<Measurement and evaluation method>
First, measurement methods and evaluation methods for various physical property values of samples obtained in Examples and Comparative Examples will be described. Hereinafter, the film take-up (flow) direction is indicated as MD, and its orthogonal direction is indicated as TD.

(3D surface roughness)
The surface (resin layer A) of the reflecting material (sample) is observed under the following apparatus and conditions, the obtained image is analyzed, the surface average roughness (hereinafter referred to as “Sa”), and the maximum height. (Hereinafter referred to as “Sz”) was calculated. The calculation was based on JIS B0601: 2001.
Apparatus: Electron beam three-dimensional roughness analyzer "ERA-4000" (manufactured by Elionix)
Deposition conditions: 10 mA × 100 sec, Pt—Pd deposition acceleration voltage: 10 kV
Observation magnification: 250 times Analysis area: 360 (μm) × 480 (μm)

(Bending stiffness)
In accordance with JIS P-8125, the bending stiffness (g · cm) was measured under the following conditions.
Measuring device: Friction fastness testing device (Daiei Scientific Instruments)
Bending angle: 15 degrees

(Apparent viscosity)
Measuring device: Koka type flow tester (CFT-500C / Shimadzu Corporation)
Measurement conditions: Nozzle φ1 × L10mm
Temperature: 230 (° C)
Shear rate: 100 (1 / sec)

(Light guide plate adhesion unevenness)
The default reflective material of the following display was sequentially replaced with the reflective material produced in the example, and light guide plate adhesion unevenness was measured according to the following method.

The display was placed on a horizontal measuring table, and a total of four weights of 500 g were placed at the four corners of the display, and the light source was turned on with a certain load applied. A standard deviation and a value of (maximum value) / (average value) of luminance were calculated from the display luminance dot data by a luminance unevenness meter (CA2000, manufactured by KONIKA MINOLTA), and used as an index of luminance unevenness.
《Display used》
Model name: LCD-8000V (CENTURY)
Light source: LED (long side x 1 row arrangement)
Size: 8 inches

<Example 1>
(Preparation of resin composition A of resin layer (A))
Amorphous cycloolefin resin A (manufactured by Nippon Zeon Co., Ltd., trade name “ZEONOR RCY15”, hydrogenated product of cyclic olefin ring-opening polymer, density (ISO 1183): 1.01 g / cm ³ , MFR (230 ° C. 21.18N, JISK7210: 1.2 g / 10 min, pellets of glass transition temperature Tg (JISK7121): 127 ° C., SP value: 7.4) and amorphous cycloolefin resin B (manufactured by Zeon Corporation) Trade name “Zeonor 1060R”, hydrogenated cyclic olefin ring-opening polymer, density (ISO 1183): 1.01 g / cm ³ , MFR (230 ° C., 21.18 N, JIS K7210): 12 g / 10 min, glass transition temperature Tg (JISK7121): 100 ° C., SP value: 7.4) pellets and polypropylene resin (Japan) Product name “NOVATEC PP EA9”, manufactured by Polypro Corporation, density (JISK7112): 0.9 g / cm ³ , MFR (230 ° C., 21.18 N, JISK-7210): 0.5 g / 10 min, SP value: 8. 0) pellets were mixed in a mass ratio of 50:25:25, and then pelletized using a twin-screw extruder heated to 230 ° C. to prepare a resin composition A.

(Preparation of resin composition B of resin layer (B))
Polypropylene resin (manufactured by Nippon Polypro Co., Ltd., trade name “NOVATEC PP FY6HA”, density (JISK7112): 0.9 g / cm ³ , MFR (230 ° C., 21.18 N, JISK-7210): 2.4 g / 10 min) Pellets and titanium oxide (trade name “KRONOS2230”, density 4.2 g / cm ³ , rutile titanium oxide, Al, Si surface treatment, TiO ₂ content 96.0%, production method: chlorine method, manufactured by KRONOS) Were mixed at a mass ratio of 50:50, and then pelletized using a twin-screw extruder heated at 270 ° C. to prepare a resin composition B.

(Production of reflective material)
The resin compositions A and B are respectively supplied to extruders A and B heated to 230 ° C. and 200 ° C., and melt-kneaded at 230 ° C. and 200 ° C. in each extruder, and then used for two types and three layers. The sheet was joined to a T-die, extruded into a sheet shape so as to have a three-layer structure of resin layer (A) / resin layer (B) / resin layer (A), and cooled and solidified to form a laminated sheet.
The obtained laminated sheet was roll-stretched 2.5 times to MD at a temperature of 135 ° C., and further biaxially stretched by tenter-stretching 2.5 times to TD at 140 ° C. to obtain a thickness of 225 μm (resin layer (A): 185 μm, resin layer (B): 20 μm A reflection material (sample) having a lamination ratio A: B = 4.6: 1) was obtained.
The obtained reflector was evaluated for three-dimensional surface roughness (surface average roughness: Sa, maximum height: Sz) and light guide plate adhesion luminance unevenness.

<Example 2>
In the production of the resin composition A of Example 1, pellets of amorphous cycloolefin resin A (made by Nippon Zeon Co., Ltd., trade name “Zeonor RCY15”) and polypropylene resin (made by Nippon Polypro Co., Ltd., trade name “ Novatec PP EA9 ") and amorphous cycloolefin resin C (Topas Advanced Polymers GmbH, trade name" TOPAS 8007F ", density (ISO 1183): 1.01 g / cm ³ , MVR (260 ° C, 2. 16 kg, ISO1133): 32 ml / 10 min, glass transition temperature Tg (DSC, ISO11375-1, 2, 3): point of mass ratio with pellets of 78 ° C., SP value 8.8) 70:15:15 A reflector (sample) having a thickness of 225 μm was obtained in the same manner as in Example 1 except that . Evaluation similar to Example 1 was performed about the obtained reflecting material.

<Example 3>
In the production of the resin composition A of Example 1, a pellet of amorphous cycloolefin resin A (manufactured by Zeon Corporation, trade name “Zeonor RCY15”) and amorphous cycloolefin resin C (“TOPAS 8007F”). )) And polypropylene resin (made by Nippon Polypro Co., Ltd., trade name “NOVATEC PP EA9”) were mixed in a mass ratio of 60:20:20 in the same manner as in Example 1. A reflective material (sample) having a thickness of 225 μm was obtained. The obtained reflector was evaluated for bending stiffness together with the same evaluation as in Example 1.

<Comparative Example 1>
In the production of the resin composition A of Example 1, pellets of amorphous cycloolefin resin A (made by Nippon Zeon Co., Ltd., trade name “Zeonor RCY15”) and polypropylene resin (made by Nippon Polypro Co., Ltd., trade name “ A reflector (sample) having a thickness of 225 μm was obtained in the same manner as in Example 1 except that pellets of Novatec PP EA9 ”) were mixed at a mass ratio of 60:40. Evaluation similar to Example 1 was performed about the obtained reflecting material.

<Comparative example 2>
In the production of the resin composition A of Example 1, a pellet of amorphous cycloolefin resin A (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor RCY15”) and amorphous cycloolefin resin B (Nippon Zeon Corporation) Product name “Zeonor 1060R”, density (ISO1183): 1.01 g / cm ³ , MFR (230 ° C., 21.18 N, JISK7210: 14.0 g / 10 min, glass transition temperature Tg (JISK7121): 100 ° C. Example 1 except that pellets of SP value 7.4) and polypropylene resin (trade name “Novatech PP EA9” manufactured by Nippon Polypro Co., Ltd.) were mixed at a mass ratio of 70:10:20. A reflective material (sample) having a thickness of 225 μm was obtained in the same manner as in Example 1. The obtained reflective material was evaluated in the same manner as in Example 1.

<Reference Example 1>
In Example 3 (Preparation of reflector), the thickness of the sheet was 300 μm (resin layer (A): 185 μm, resin layer (B): 20 μm, lamination ratio A: B = 4.6: 1). Except for this, a reflector (sample) was obtained in the same manner as in Example 3. Evaluation similar to Example 3 was performed about the obtained reflecting material.

<Reference Example 2>
In the production of the resin composition A of Example 1, a pellet of amorphous cycloolefin resin C (manufactured by Nippon Zeon Co., Ltd., trade name “Zeonor RCY50”, SP value: 7.4) and amorphous cycloolefin Thickness similar to that of Example 1 except that pellets of a resin B (made by Nippon Zeon Co., Ltd., trade name “Zeonor 1060R”, SP value: 7.4) were mixed at a mass ratio of 67:33 A reflective material (sample) having a thickness of 225 μm was obtained. The obtained reflective material was evaluated for three-dimensional surface roughness.

  Table 2 shows a recipe for the examples and comparative examples. Regarding the COP of the sea phase component, the apparent viscosity was adjusted by blending two kinds, and the influence of the difference in the apparent viscosity on the three-dimensional surface roughness was confirmed.

  Table 3 shows the SP value and the absolute value of the difference in the mixed system of two or more thermoplastic resins for the examples and comparative examples.

  Table 4 shows the apparent viscosity and the absolute value of the difference in a mixed system of two or more kinds of thermoplastic resins for Examples and Comparative Examples.

Table 5 shows the evaluation results of surface roughness and light guide plate adhesion luminance unevenness for Examples, Comparative Examples, and Reference Examples. In determining whether or not unevenness of the light guide plate contact luminance is possible, a range in which the value of (maximum value) / (average value) of luminance does not exceed 2.0 is acceptable. Note that the smaller the standard deviation of luminance, the smaller the luminance unevenness.
Reference Example 2 is an example in which the absolute value of the difference in SP value is 0, which is not a mixed system of two or more thermoplastic resins.

From Tables 2 to 5, the following became clear.
(1) The higher the surface average roughness, the more uneven the light guide plate adhesion luminance can be suppressed, and the value of the surface average roughness (Sa) of the resin layer (A) is 0.90 or more, thereby sufficiently adhering the light guide plate. Brightness unevenness can be suppressed.
(2) The larger the SP value difference between the sea phase (COP phase in the embodiment) and the island phase, the larger the surface average roughness (Sa), and in particular, the maximum SP value difference between the sea phase and the island phase is 1 By setting it to 4 or more, the surface average roughness (Sa) of the resin layer (A) can be 0.90 or more.
(3) The smaller the absolute value of the difference in apparent viscosity between the sea phase and the island phase, the greater the surface average roughness (Sa). For example, when the absolute value of the difference between the maximum SP values of the sea phase and the island phase is 0.8, the absolute value of the difference in apparent viscosity between the sea phase of the sea-island structure (COP phase in the embodiment) and the island phase. : | Η (Pa · s) | is 1000 (Pa · s) or less, whereby the surface average roughness (Sa) of the resin layer (A) can be 0.90 or more.
(4) From the comparison between Example 3 and Reference Example 1, even with the same material, the higher the bending stiffness (the rigidity of the sheet itself), the better the light guide plate contact luminance unevenness can be suppressed.
(5) It is considered that the higher the rigidity of the sheet itself, the more difficult the deformation of the reflecting material following the deformation of the light guide plate occurs, and it is possible to suppress adhesion.

Claims (14)

  The outermost layer, which is the reflective surface, is not a coating layer having a concavo-convex structure formed by organic or inorganic spherical fine particles, but the surface average roughness (Sa) of the three-dimensional surface roughness is 0.90 μm or more. A reflective material comprising a resin layer (A). The resin layer (A) is composed of a mixture of two or more thermoplastic resins having an absolute value of a difference in solubility parameter (SP value) of 0.3 to 3.0 (cal / cm ³ ) ^0.5. The reflective material according to claim 1. The resin layer (A) has a sea-island structure formed by mixing two or more kinds of thermoplastic resins, and the absolute value of the difference in SP value between the sea phase and the island phase (however, the island phase has a plurality of island phases) In the case of a phase, the absolute value of the difference between the maximum SP value of the sea phase and the island phase is 1.4 (cal / cm ³ ) ^0.5 or more, or the difference of the SP value between the sea phase and the island phase is 0. 6 (cal / cm ³ ) The reflection according to claim 1, which is ^0.5 or more and less than 1.4, and the absolute value of the difference in apparent viscosity between the sea island and the island phase is 1000 (Pa · s) or less. Wood.   The reflective material according to claim 2 or 3, wherein the two or more thermoplastic resins occupy 70 mass% or more of the entire resin constituting the resin layer (A).   The at least 1 type of resin which comprises the said resin layer (A) is an amorphous resin whose glass transition temperature (JISK7121) is 85-150 degreeC, The any one of Claims 1-4 characterized by the above-mentioned. Reflective material.   The reflective material according to claim 5, wherein the amorphous resin is a cycloolefin resin.   The reflective material according to any one of claims 1 to 6, comprising a configuration having a resin layer (B) having voids inside, in addition to the resin layer (A).   The reflective material according to claim 7, wherein the resin layer (B) contains a fine powder filler.   The reflective material of Claim 7 or 8 whose porosity of the said resin layer (B) is 20% or more and 70% or less.   The reflector according to any one of claims 7 to 9, wherein the resin layer (B) contains an olefin resin.   11. The reflection according to claim 7, wherein the total thickness ratio of the resin layer (A) and the resin layer (B) is (A) :( B) = 1: 3 to 1:15. Wood.   The liquid crystal display using the reflecting material as described in any one of Claims 1-11.   The lighting fixture using the reflecting material as described in any one of Claims 1-11.   The illumination signboard using the reflecting material as described in any one of Claims 1-11.

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