JP6459950B2 - Reflective film, and liquid crystal display device, lighting device, and decorative article comprising the same - Google Patents

Description

  The present invention relates to a reflective film that reflects light, for example, a reflective film that can be suitably used as a constituent member of a liquid crystal display device, a lighting fixture, or a lighting signboard.

  Reflective materials are used in many fields such as liquid crystal display devices, lighting fixtures or lighting signs. Recently, particularly in the field of liquid crystal displays, the size of the apparatus and the advancement of display performance have advanced, and it has been required to improve the performance of the backlight unit by supplying as much light as possible to the liquid crystal. For this reason, for the reflective material, from the viewpoint of improving the luminance of the backlight unit and the luminance uniformity, it is possible to improve the light reflectivity (simply referred to simply as “reflective”) and light diffusibility (simply referred to as “diffusible”). Say).

  As a reflective film showing high reflectivity and diffusivity, for example, by stretching a film formed by adding a filler to a resin, fine voids are formed in the film, and light scattering reflection is caused. White films are known.

  In this type of reflective film, the light reflectivity is determined by the difference in refractive index between the base resin and the filler, the difference in refractive index between the base resin and the gap, and the difference in refractive index between the filler and the gap. Since the higher the light reflectivity, the higher the refractive index, titanium oxide is used as a high refractive index filler.

  For example, Patent Document 1 discloses a substantially unstretched film having an A layer composed of a resin composition A containing a resin having a refractive index of less than 1.52 and titanium oxide and having an area magnification of less than 1.2. The titanium oxide has a refractive index of 2.5 or more, the vanadium content in the titanium oxide is 5 ppm or less, and the reflectance of the film with respect to light having a wavelength of 550 nm is 98.1% or more, In addition, the thermal shrinkage rate after the treatment at 80 ° C. for 180 minutes is characterized in that both the machine direction (MD) and the transverse direction (TD) are greater than −0.1% and less than 1.0%. A reflective film is disclosed.

A reflective film provided with a layer having a sea-island structure is also disclosed.
For example, Patent Document 2 discloses a reflective film containing at least one thermoplastic resin and having at least one layer having a sea-island structure composed of a continuous phase (I) and a dispersed phase (II), wherein the dispersed phase ( The average dimension (L1) in the flow direction of II) and the average dimension (L2) in the width direction are 0.45 μm or more and 100 μm or less, and the average dimension (L3) in the thickness direction of the dispersed phase (II) is The average refractive index difference between the thermoplastic resin (A) forming the continuous phase (I) and the thermoplastic resin (B) forming the dispersed phase (II) is 0.01 μm or more and 0.45 μm or less. Has a thickness of 0.05 or more, and an average reflectance at a measurement wavelength of 400 nm to 700 nm of the film is 80% or more.

  Similarly, regarding a reflective film including a layer having a sea-island structure, Patent Document 3 includes at least two types of thermoplastic resins, and includes at least a layer having a sea-island structure by a continuous phase (I) and a dispersed phase (II). A reflective film having one layer, wherein either the thermoplastic resin (A) forming the continuous phase (I) or the thermoplastic resin (B) forming the dispersed phase (II) is a polyester resin. Is disclosed, and the other has a fluorine-based resin as a main component, and a melting endothermic peak temperature of the fluorine-based resin is 130 ° C. or higher and 250 ° C. or lower.

JP 2012-77311 A JP 2014-186318 A JP 2014-186319 A

As an example of a liquid crystal display screen in which this type of reflective film is incorporated, in an edge light type backlight unit of a liquid crystal display, a light source such as a cold cathode tube or a white LED is disposed along the edge of the light guide plate, and the light source A part of the light emitted from the light is directly guided to the light guide plate, while the remaining light is reflected by the reflection film disposed around the back of the light source and guided to the light guide plate, and then guided to the light guide plate. Examples of the liquid crystal display device include a configuration in which the light is reflected by a light diffusion layer printed in a dot pattern on the back surface of the light guide plate and emitted from the light guide plate surface (illumination surface) to the liquid crystal panel side.
Taking the liquid crystal display device having such a configuration as an example, the light leaked from the light guide plate is reflected by the reflective film provided on the back side of the light guide plate and goes out of the surface of the light guide plate. In order to improve the display quality of the liquid crystal, it is necessary to supply as much light as possible to the liquid crystal panel. Therefore, in order to save power and increase the amount of light supplied from the backlight as much as possible, it is required that the reflection film has high reflection efficiency and high luminance.
Moreover, in order to suppress the brightness difference between the place with and without the light source to suppress so-called brightness spots, it is required to improve the brightness of the reflective film.

  Therefore, the present invention intends to provide a new reflective film that can improve the luminance as well as the reflectance.

The present invention comprises a reflective layer X containing a polyester-based resin (A) and a filler and having voids, and a sea island comprising two types of resins (B) and (C) disposed on both front and back sides of the reflective layer X It has a two-layer three-layer structure of reflecting layers Y and Y having a structure, and the “thickness-void coefficient” calculated by the left expression of the following (Expression 1) satisfies the following (Expression 1). Propose a reflective film.
(Formula 1) .. Total thickness of film (μm) × Porosity of film (%) × Thickness occupation ratio of reflection layer X (%) ≧ 1300

  The reflective film proposed by the present invention includes a reflective layer X containing a polyester resin (A) and a filler, and reflective layers Y and Y having a sea-island structure composed of two types of resins (B) and (C). In a reflective film having a two-layer / three-layer structure, the luminance can be improved together with the reflectance by adjusting the thickness and the porosity.

  Hereinafter, embodiments of the present invention will be described.

<This reflective film>
The reflective film (referred to as “the present reflective film”) according to an example of the embodiment of the present invention contains a polyester-based resin (A) and a filler, and has a reflective layer X having voids, and two types of resins (B ) A reflective film having a two-layer three-layer structure with a reflective layer Y, Y having a sea-island structure made of (C).

<Reflection layer X>
The reflective layer X is a layer containing a polyester resin (A) having an alicyclic structure as a diol component and a filler, and containing voids.
Since the reflective layer X contains a filler, in addition to refractive scattering due to a difference in refractive index with the polyester resin (A), a cavity formed around the filler (exactly air in the cavity, which will be described later). The same can be said for the cavity.) The light reflectivity can also be obtained from the refractive scattering due to the difference in refractive index with respect to the cavity and the refractive scattering due to the difference in refractive index between the cavity and the filler formed around the filler. In addition to refractive scattering due to the difference in refractive index between the polyester resin (A) and the filler, refractive scattering due to the difference in refractive index from the cavity formed around the filler, as well as the cavity and filling formed around the filler. Light reflectivity can also be obtained from refractive scattering due to a difference in refractive index with the material.

(Polyester resin (A))
The polyester resin (A) preferably contains a diol component having an alicyclic structure in a molar ratio of 5 to 50%. If the polyester-based resin (A) containing the diol component in a molar ratio of 5 to 50%, a high Tg can be obtained as compared with a normal polyester resin, and therefore a difference in glass transition temperature from the reflective layer Y described later. Is preferable in that it can be adjusted to a desired range.
From this point of view, the polyester-based resin (A) preferably contains a diol component having an alicyclic structure in a molar ratio of 5 to 50%, especially 10% or more or 45% or less, of which 15% or more. Or it is further more preferable to contain in the ratio of 40% or less.

The polyester resin (A) may be any polyester resin having an alicyclic structure as a diol component. Examples thereof include a resin having a diol component having at least one alicyclic structure selected from spiro glycol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.
By using a polyester resin having an alicyclic structure as the diol component as the polyester resin (A), the voids of a more uniform size and shape can be made more uniform than when other polyester resins are used. It can disperse | distribute and can further improve light reflectivity.
Moreover, the polyester-type resin which has alicyclic structure as a diol component is preferable also at the point of having high Tg while having a low refractive index, the outstanding transparency, and the outstanding softness | flexibility.
However, from the viewpoint of adjusting the glass transition temperature (Tg) and the refractive index, other polyester resins and additives may be used in combination in addition to the above resins.

  The glass transition temperature (Tg) of the polyester resin (A) is preferably 100 to 130 ° C., more preferably 105 ° C. or more and 125 ° C. or less, and particularly preferably 110 ° C. or more and 120 ° C. or less.

(Filler)
Examples of the filler used for the reflective layer X include inorganic fine powder and organic fine powder.

Examples of the inorganic fine powder 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 , Mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay and the like. Any one of these may be used, or two or more may be mixed and used.
Among these, considering the difference in refractive index with the polyester-based resin, those having a large refractive index are preferable, and it is particularly preferable to use calcium carbonate, barium sulfate, titanium oxide or zinc oxide having a refractive index of 1.6 or more. preferable.

Among them, titanium oxide has a significantly higher refractive index than other fillers, and has a remarkably large difference in refractive index from the polyester-based resin. Therefore, titanium oxide is superior in a smaller amount than when other fillers are used. Reflectivity can be obtained. Further, by using titanium oxide, high light reflectivity can be obtained even if the thickness of the reflective layer X or the present reflective film is reduced.
Therefore, it is more preferable to use a filler containing at least titanium oxide as a main component. In this case, the amount of titanium oxide is 30% by mass or more of the total mass of the inorganic filler, or an organic filler and an inorganic filler. When used in combination, it is preferably 30% by mass or more of the total mass.

  In order to improve the dispersibility of inorganic fine powder in resin, the surface of the filler is treated with silicon compound, polyhydric alcohol compound, amine compound, fatty acid, fatty acid ester, etc. May be.

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

  The filler in the reflective layer X preferably has an average particle size (D50) of 0.05 μm to 15 μm, more preferably 0.1 μm or more or 10 μm or less. If the average particle diameter (D50) of the filler is 0.05 μm or more, the dispersibility in the polyester-based resin does not deteriorate, so a homogeneous layer can be obtained. On the other hand, if the average particle diameter (D50) of the filler is 15 μm or less, the interface between the polyester resin and the filler is formed densely, and the reflectivity can be further enhanced.

In the reflective layer X, the content ratio (parts by mass) of the polyester resin (A) and the filler is polyester resin (A): filler from the viewpoint of light reflectivity, mechanical strength, productivity, and the like. = It is preferable that it is 20: 80-80: 20. If the content of the filler is 20 parts by mass or more with respect to 80 parts by mass of the polyester-based resin (A), the area of the interface between the base resin and the filler can be sufficiently secured, and the reflective material has a high Reflectivity can be imparted. On the other hand, if the content of the filler is 80 parts by mass or less with respect to 20 parts by mass of the polyester resin (A), the mechanical strength required for the reflective sheet can be ensured.
From this viewpoint, in the reflective layer X, the polyester resin (A): filler is preferably 20:80 to 80:20, and particularly preferably 40:60 to 60:40 parts by mass.

(Formation method)
The reflective layer X can be formed from, for example, a film obtained by uniaxially or biaxially stretching a film containing a polyester resin (A) having an alicyclic structure as a diol component and a filler. However, the present invention is not limited to this.

The stretching method is preferably oriented in the biaxial direction of the film flow direction (hereinafter sometimes referred to as MD) and the width direction (hereinafter sometimes referred to as TD).
Under the present circumstances, as a draw ratio of the reflection layer X, what is extended | stretched 2-9 times in the flow direction of a film and / or the width direction of a film is preferable.

(Void)
The reflective layer X is a layer having a gap.
The gap of the reflective layer X preferably has a flat plate structure like the dispersion layer of the reflective layer Y. In that case, it is preferable that the thickness of the gap of the reflective layer X is thicker than the thickness of the dispersion layer of the reflective layer Y.
The porosity of the reflective layer X is preferably 5% to 70%, more preferably 10% or more and 65% or less, and more preferably 15% or more and 60% or less.

  Examples of the method for forming voids in the reflective layer X include, for example, a method of stretching at least in a uniaxial direction, a method of adding foamable particles and foaming the film by melt extrusion, and an inert gas. And a method of forming a porous layer by releasing the pressure, and the like. Any one of these methods may be employed, or a plurality of methods may be combined.

<Reflection layer Y>
The reflective layer Y is a layer having a sea-island structure made of two types of resins (B) and (C).

The two types of resins (B) are preferably thermoplastic resins having a glass transition temperature difference of 15 ° C. or less from the polyester resin (A).
If the reflective layer Y is a layer containing, as a main component resin, a thermoplastic resin (B) having a glass transition temperature difference of 15 ° C. or less from the polyester-based resin (A), as described later, the reflective layer Since X and the reflective layer Y can be coextruded and laminated, not only the production efficiency is increased, but the reflective layer X and the reflective layer Y can be directly laminated without an intermediate layer such as an adhesive layer. The reflective film can be formed thinner.
From such a viewpoint, the difference (absolute value) in glass transition temperature between the polyester resin (A) and the thermoplastic resin (B) is preferably 15 ° C. or less, particularly 13 ° C. or less, and more preferably 11 ° C. or less. Is particularly preferred.

The reflective layer Y has a sea-island structure composed of a continuous phase (I) made of the thermoplastic resin (B) and a dispersed phase (II) made of an incompatible thermoplastic resin (C). preferable.
Sea-island structure refers to a structure in which one of a plurality of components is dispersed in a phase in which the other is dispersed in the form of particles (islands). Usually, the island part that is a dispersed phase is discontinuous, And it shows a minute, substantially spherical structure. Since the island part of the reflective layer Y in this reflective film is extended | stretched in a flow direction and the width direction, it is preferable to show a flat elliptical structure or a disk-shaped structure. The presence or absence of such a structure can be confirmed by observing the MD cross section or TD cross section of the reflective layer Y with a scanning electron microscope (SEM).

Regarding the thermoplastic resin (B) that forms the continuous phase (I) and the thermoplastic resin (C) that forms the dispersed phase (II) in the reflective layer Y, the thermoplastic that forms the continuous phase (I) The average refractive index difference between the resin (B) and the thermoplastic resin (C) forming the dispersed phase (II) is preferably 0.05 or more.
When the average refractive index difference between the two is 0.05 or more, light is easily reflected at the interface between the continuous phase and the dispersed phase, so that higher reflection characteristics can be imparted.
For this reason, the average refractive index difference between the thermoplastic resin (B) forming the continuous phase (I) and the thermoplastic resin (C) forming the dispersed phase (II) is 0.10 or more. Is more preferable and 0.15 or more is further preferable.

The reflective layer Y is preferably formed from a film oriented at least in a uniaxial direction, and above all, the film flow direction (hereinafter sometimes referred to as MD) and the width direction (hereinafter referred to as TD). It is more preferable that they are oriented in the biaxial direction.
By imparting orientation to the film by a stretching operation or the like, the refractive index of the thermoplastic resin (B) that forms the continuous phase (I) and the thermoplastic resin (C) that forms the dispersed phase (II) By changing it, it becomes possible to further increase the refractive index difference between (B) and (C). Moreover, the average dimension of the flow direction of the said disperse phase (II), the width direction, and the thickness direction can be adjusted, and a high reflective characteristic can be provided with this reflective film.

The thermoplastic resin (B) that forms the continuous phase (I) and the thermoplastic resin (C) that forms the dispersed phase (II) may be one kind of thermoplastic resin, or two or more kinds. It may be a mixed resin of these thermoplastic resins.
Among them, it is preferable that at least one of the thermoplastic resin (B) forming the continuous phase (I) and the thermoplastic resin (C) forming the dispersed phase (II) is a crystalline thermoplastic resin. . If at least one is a crystalline thermoplastic resin, the polymer chain is easily oriented, the refractive index difference between the continuous phase (I) and the dispersed phase (II) with respect to the orientation direction is easily increased, and the reflection characteristics are easily improved. Therefore, it is preferable. Further, during the heat treatment, the crystalline thermoplastic resin is easily oriented and crystallized, which is preferable from the viewpoint of dimensional stability.

  The crystalline thermoplastic resin generally refers to a thermoplastic resin that has a crystal melting peak temperature (melting point), and more specifically, in differential scanning calorimetry (DSC) performed in accordance with JIS K7121. Thermoplastic resins whose melting point is observed include those in a so-called semi-crystalline state. Conversely, a thermoplastic resin whose melting point is not observed in DSC is referred to as “amorphous”.

  The kind of the crystalline thermoplastic resin is not particularly limited. For example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene succinate, polybutylene succinate, polylactic acid, poly-ε-caprolactam Resin, polyethylene resin such as high density polyethylene, low density polyethylene, linear polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester Polymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-vinyl acetate-vinyl chloride copolymer, ethyne-α olefin copolymer, etc. No Tylene copolymer, polypropylene resin, polybutene resin, polyamide resin, polyoxymethylene resin, polymethylpentene resin, polyvinyl alcohol resin, polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene Fluorine-based resins such as resin, cellulose-based resins, polyether ether ketone, polyether ketone, polyphenylene sulfide, engineering plastics such as polyparaphenylene terephthalamide, and super engineering plastics. Of these, polyester resins are preferable, and crystalline aromatic polyester resins are more preferable.

From the above viewpoint, the reflective layer Y is preferably formed by forming a sea-island structure by a combination of a polyester resin and a fluorine resin.
Among them, a combination in which the thermoplastic resin (B) that forms the continuous phase (I) is a polyester resin and the thermoplastic resin (C) that forms the dispersed phase (II) is a fluorine resin is preferable.
Generally, polyester resins, especially aromatic polyester resins, have a high average refractive index, and fluorine resins have a low average refractive index. Therefore, it is easy to increase the difference in refractive index between the continuous phase (I) and the dispersed phase (II). It is preferable because the characteristics are easily improved.

(Polyester resin)
The polyester resin as the constituent material of the reflective layer Y is preferably a crystalline polyester resin.
When the crystalline polyester resin is stretched, the polymer chain is easily oriented, the difference in refractive index between the continuous phase (I) and the dispersed phase (II) with respect to the orientation direction is easily increased, and the reflection characteristics are easily improved. Therefore, it is preferable. In addition, orientation crystallization is facilitated during the heat treatment, which is preferable from the viewpoint of dimensional stability.
In general, polyester-based resins often have a positive intrinsic birefringence, and aromatic polyester-based resins have a high birefringence, so that the refraction of the continuous phase (I) and the dispersed phase (II) with respect to the orientation direction. It is preferable because the rate difference is easily increased and the reflection characteristics are easily improved.

Such a polyester resin is not particularly limited in its kind. For example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene succinate, polybutylene succinate, polylactic acid, poly-ε-caprolactam Based resins and the like.
Among these, a crystalline aromatic polyester-based resin is preferable, and a polyethylene naphthalate-based resin is particularly preferable from the viewpoint of having a high average refractive index and a high birefringence. Further, from the viewpoint of adjusting the glass transition temperature (Tg) and the refractive index, the above resins may be used in combination.
A mixed resin of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) is also a preferred example. Since PEN and PET are compatible, Tg and refractive index can be adjusted by mixing PET with PEN.

  When a polyethylene naphthalate resin is used, the weight average molecular weight of the resin is preferably 30,000 or more, more preferably 40,000 or more from the viewpoint of impact resistance and film-forming properties.

The intrinsic viscosity of the polyester resin is more preferably 0.5 dl / g or more from the viewpoint of film forming properties.
The glass transition temperature (Tg) of the polyester resin is preferably in the range of 70 ° C to 120 ° C, and more preferably in the range of 80 ° C to 120 ° C. If the glass transition temperature is 70 ° C. or higher, the rigidity of the film can be maintained, and if it is 120 ° C. or lower, stretching becomes easy.
Furthermore, the melting point (Tm) of the polyester resin is preferably in the range of 240 ° C to 270 ° C, and more preferably in the range of 250 ° C to 270 ° C. If the melting point is 240 ° C. or higher, sufficient heat resistance can be imparted, and if it is 270 ° C. or lower, it is preferable to suppress thermal decomposition of the coexisting thermoplastic resin other than the polyethylene naphthalate resin during melt extrusion. .

  When a polyethylene naphthalate resin is used as the polyester resin, it is preferable to use one having a YI value in the range of −10 to 10, particularly in the range of −3 to 3. When the polyethylene naphthalate resin is made of a mixture, the YI value of each resin is preferably in the range of −10 to 10. If the YI value is in the range of −10 to 10, for example, by incorporating it in a liquid crystal display or the like, it is possible to further improve the clarity of the image and to further increase the luminance improvement rate.

  A commercial item can also be used as a polyethylene naphthalate-type resin. For example, Teonex TN8065S (polyethylene naphthalate homopolymer, manufactured by Teijin Chemicals Ltd., intrinsic viscosity 0.71 dl / g), Teonex TN8065SC (polyethylene naphthalate homopolymer, manufactured by Teijin Chemicals Ltd., intrinsic viscosity 0.55 dl) / G), Teonex TN8756C (polyethylene naphthalate and polyethylene terephthalate copolymer, manufactured by Teijin Chemicals Ltd., intrinsic viscosity 0.65 dl / g) and the like can be mentioned as preferred examples.

(Fluorine resin)
On the other hand, the fluororesin as the constituent material of the reflective layer Y preferably has a melting point (Tm) of 130 ° C. or higher and 250 ° C. or lower.
When the melting point of the fluororesin is less than 130 ° C., it is not preferable because surface roughness occurs during kneading / extrusion with the polyester resin and the heat resistance of the reflective film decreases. Since the reflective film is often disposed around the light source due to its properties, heat resistance is required. Therefore, the melting point of the fluororesin is preferably 130 ° C. or higher, more preferably 150 ° C. or higher, and particularly preferably 180 ° C. or higher.
Further, when the melting point of the fluororesin exceeds 300 ° C., it is not preferable because decomposition of the polyester resin is easily promoted during kneading / extrusion with the polyester resin and molding becomes difficult. Furthermore, when the melting point of the fluororesin is higher than 250 ° C. and lower than 300 ° C., the surface becomes rough and the morphology of the dispersed phase (II) tends to become rough, which is not preferable. For this reason, the melting point of the fluororesin is preferably 245 ° C. or lower, more preferably 240 ° C. or lower, and particularly preferably 235 ° C. or lower.

  The fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin or an ethylene-tetrafluoroethylene resin because it has a low average refractive index and excellent stretchability. preferable.

  For example, when the tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin or the ethylene-tetrafluoroethylene resin is used, the melting point (Tm) of the fluorine resin is 130 for the purpose of imparting heat resistance. The range of ° C to 250 ° C is preferable, and the range of 180 ° C to 240 ° C is more preferable.

  Commercially available products may be used as the tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin and the ethylene-tetrafluoroethylene resin. For example, the Dyneon series (manufactured by 3M), Fluon ETFE, Fluon LM-ETFE, Fluon LM-ETFE AH series (manufactured by Asahi Glass Co., Ltd.), NEOFLON ETFE EP series (manufactured by Daikin Industries, Ltd.) and the like can be mentioned as preferred examples.

(Ratio of thermoplastic resin (B) (C))
The mixing mass ratio of the thermoplastic resin (B) forming the continuous phase (I) and the thermoplastic resin (C) forming the dispersed phase (II) constituting the reflective layer Y is (B) / ( C) = 90/10 to 50/50, preferably 80/20 to 55/45, and particularly preferably 75/25 to 60/40. Such a mixing mass ratio is preferable because the dispersed phase does not decrease too much, and scattering at the interface between the continuous phase and the dispersed phase is reduced and there is no fear that the reflection characteristics are deteriorated.
The reflective layer Y may contain a thermoplastic resin other than the thermoplastic resin (B) and the thermoplastic resin (C). For example, two or more thermoplastic resins corresponding to the thermoplastic resin (C) may be included.

(Other ingredients)
The reflective layer Y may contain additives such as a compatibilizer as necessary for the purpose of improving dispersibility.

  The compatibilizer can be selected from conventional compatibilizers according to the type of continuous phase and dispersed phase in the reflective layer Y. For example, a polycarbonate resin, an ester resin, a resin having an epoxy group, an oxazoline ring And a block copolymer or a graft copolymer comprising at least one resin selected from a resin having an azlactone group and at least one resin selected from a styrene resin, polyphenylene oxide, and polyamide. Among these, from the viewpoint of improving dispersibility, a resin having an epoxy group or an oxazoline group is particularly preferable, and an epoxy-modified one is particularly preferable.

  When the compatibilizing agent is added, the blending ratio is 0.1 to 20 parts by mass, preferably 0.2 to 0.1 parts by mass with respect to 100 parts by mass in total of the thermoplastic resin (B) and the thermoplastic resin (C). It is preferably 15 parts by mass, particularly 0.2 to 10 parts by mass, and more preferably 1 to 10 parts by mass.

  Further, as additives other than the compatibilizing agent, additives generally blended in the resin composition can be appropriately added within a range that does not significantly impair the effects of the present invention. Examples of the additive include additives that are added for the purpose of improving and adjusting the molding processability, productivity, and various physical properties of the reflective film, such as flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melting agents. Such as viscosity improver, crosslinking agent, lubricant, nucleating agent, plasticizer, anti-aging agent, antioxidant, light stabilizer, UV absorber, neutralizing agent, anti-fogging agent, anti-blocking agent, slip agent or coloring agent An additive is mentioned. Specifically, the interfaces as antioxidants described in P154 to P158 of PLASTICS compounding agents, UV absorbers described in P178 to P182, and antistatic agents described in P271 to P275 Activators, lubricants described in P283 to P294, and the like.

(Formation method)
The reflective layer Y can be formed, for example, by uniaxially or biaxially stretching a film having a sea-island structure made of two types of resins (B) and (C).

(Void)
The reflective layer Y preferably has substantially zero porosity.
Here, “substantially zero” is not intended to provide a gap in the reflective layer Y, but is intended to allow the inclusion of an inevitably formed gap. From this viewpoint, if the porosity of the reflective layer Y is less than 3%, particularly less than 2%, and less than 1%, it can be regarded as substantially zero.

<Thickness and porosity>
In the present reflective film, it is preferable that the thickness-gap coefficient calculated by the following left equation (Equation 1) satisfies (Equation 1). The “thickness occupancy ratio of the reflective layer X” is the ratio of the thickness of the reflective layer X to the thickness of the entire reflective film.
(Formula 1) .. Total thickness of film (μm) × Porosity of film (%) × Thickness occupation ratio of reflection layer X (%) ≧ 1300

If this thickness-void coefficient is 1300 or more, the present reflective film is preferable because it can increase the reflectance and reduce the transmittance.
From this viewpoint, the thickness-void coefficient of the present reflective film is preferably 1300 or more, more preferably 1500 or more and 15000 or less, and particularly preferably 2000 or more and 10,000 or less.

(Thickness of the reflective film)
The thickness of the reflective film is preferably 40 μm to 300 μm. If the thickness of the reflective film is 40 μm or more, sufficient reflectance and regular reflection characteristics can be obtained, and if it is 300 μm or less, sufficient practical handling can be achieved. From this viewpoint, it is more preferably 50 μm or more and 200 μm or less, and further preferably 60 μm or more or 100 μm or less.

(Thickness occupancy ratio of reflection layers X and Y)
The thickness ratio of the reflective layer X to the total thickness of the reflective film, that is, the thickness occupancy ratio, is preferably 50 to 95% mainly from the viewpoint of increasing the reflectance, and more preferably 60% or more or 93% or less. In particular, it is more preferably 70% or more or 92% or less.
On the other hand, the thickness occupancy ratio of the reflective layer Y is preferably 5 to 50% mainly from the viewpoint of increasing the strength, more preferably 7% or more or 40% or less, and more preferably 8% or more or 30% or less. Is more preferable.
When the thickness occupancy ratio of each layer is within the above range, regular reflection characteristics and high reflectance can be efficiently imparted to the present reflective film. In addition, the strength and handling properties after lamination can be sufficiently secured.
The thicknesses of the reflection layers X and Y mean the total thickness when two or more reflection layers X and Y are present.

<Laminated structure of the reflective film>
The reflective film may be a laminated structure having a two-layer three-layer structure of the reflective layer X and the reflective layers Y and Y. The reflective layer X and the reflective layer Y are laminated and integrated by coextrusion. The configuration is particularly preferable.

At this time, the present reflective film only needs to have a laminated structure having a two-layer three-layer structure of the reflective layer X and the reflective layers Y and Y, and other layers P may be appropriately introduced as necessary. For example, it can be overlapped with a metal plate to improve mechanical properties.
For example, in addition to Y / X / Y, Y / P / X / Y, P / Y / X / Y, Y / P / X / P / Y, Y / X / P / X / P / Y, etc. Can be illustrated. However, it is not limited to these.
In addition, in setting it as a laminated structure, regarding the resin composition of each layer, you may be the same or different.

<Shape and physical properties of the reflective film>
(Average reflectance and average transmittance)
The reflective film preferably has an average reflectance of 90% or more at a measurement wavelength of 400 nm to 700 nm. When the average reflectance is 95% or more, the reflection characteristics of the film can be ensured. For this reason, it is more preferably 96% or more, and particularly preferably 97% or more. If it has such a reflection performance, it exhibits good reflection characteristics as a reflective material, and a liquid crystal display or the like incorporating this reflective material can achieve a sufficient brightness of the screen.

  Moreover, it is preferable that this reflection film has an average transmittance of 4% or less over the wavelength in the entire region at a measurement wavelength of 400 nm to 700 nm. Thereby, the transmission of the light on the back side of the reflective surface can be suppressed, and a reflective film excellent in light concealing property can be obtained.

(Regular reflection characteristics)
By providing the reflective layer Y, the present reflective film can exhibit regular reflectivity.
As an evaluation method of the reflection characteristics, there is a goniophotometric measurement. For example, when the normal direction is 0 ° with respect to the film surface and the incident angle is −X °, when the sample is incident on the sample, In the case of exhibiting diffuse reflectivity, the reflected light is reflected with a spread at various angles. On the other hand, when the sample exhibits regular reflection, the distribution of the reflected light is a reflected light distribution having a reflection angle X ° as a peak. At this time, the higher the specular reflectivity, the sharper the peak appears. At this time, the maximum intensity of the peak of the reflected light is normalized to 100%, and the light receiving angle width where the light receiving relative peak intensity is 1% and 10% when the horizontal bearing light angle and the vertical axis light receiving relative peak intensity are taken. It becomes an index of regular reflection characteristics.

Since the present reflective film includes the reflective layer Y, the light receiving angle width of the light receiving relative peak intensity of 10% can be set to 10 ° or less. When the angle is 10 ° or less, reflected light having strong directivity can be obtained with respect to the incident angle, and excellent regular reflection characteristics are exhibited. From this point of view, the light receiving angle width with a light receiving relative peak intensity of 10% is preferably 10 ° or less, more preferably 7 ° or less, and most preferably 5 ° or less.
In addition, since the reflective film includes the reflective layer Y, the light receiving angle width of the light receiving relative peak intensity of 1% can be set to 60 ° or less. If the angle is 60 ° or less, the incident light can be prevented from being lost with respect to the incident angle, and reflected light with strong directivity can be obtained, which shows excellent regular reflection characteristics. From this point of view, the light receiving angle width with a light receiving relative peak intensity of 1% is preferably 60 ° or less, more preferably 55 ° or less, and most preferably 50 ° or less.

(Surface roughness)
The surface roughness of the present reflective film, for example, the surface roughness of the reflective layer Y, is preferably 0.2 μm or less as the arithmetic average roughness Ra of at least one surface, 0.15 μm or less, of which 0.1 μm The following is more preferable.

As a means for setting the arithmetic average roughness Ra to the above-mentioned range, for example, when an ethylene-tetrafluoroethylene resin, which is a fluorine resin, is used for the dispersed phase (II), the melting point is within a predetermined range. By selecting, it can be adjusted. When the melting point of the resin is 130 ° C. or higher and 250 ° C. or lower, elongation deformation is facilitated, so that surface roughness can be prevented.
Further, during film formation, when the melted composition is extruded from the slit-shaped discharge port of the T die and solidified in close contact with the cooling roll, both sides of the melted resin composition are sandwiched between films having excellent smoothness, or Surface roughening can also be prevented by bonding one side of the melted resin composition with a film having excellent smoothness or pressing a metal film or metal belt having excellent smoothness.

<Form of the reflective film>
The form of the reflective film is not particularly limited, and may be a plate, sheet, film, or other form.

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

  As an example of the production method of the present reflective film, a reflective layer X-forming resin composition and a reflective layer Y-forming resin composition are prepared, and the reflective layers X and Y are laminated and integrated by coextrusion, and then uniaxial or biaxial. A method of stretching and producing can be mentioned.

(Preparation of resin composition for forming reflective layer X)
The polyester resin is preliminarily blended with a filler and, if necessary, other additives. Specifically, fillers and other antioxidants are added to the polyester resin as necessary, mixed with a ribbon blender, tumbler, Henschel mixer, etc., and then using a Banbury mixer, a single screw or a twin screw extruder, etc. Thus, the resin composition for forming the reflective layer X can be obtained by kneading at a temperature equal to or higher than the flow start temperature of the resin.
Further, it can be obtained by adding a predetermined amount of a polyester-based resin, a filler or the like with a separate feeder or the like and kneading them.
Also, make a so-called masterbatch that contains polyester resin and other antioxidants in high concentration in advance, and mix this masterbatch with polyester resin and filler to adjust to the desired concentration. You can also.

(Preparation of resin composition for forming reflective layer Y)
On the other hand, if necessary, a compatibilizer (D), an antioxidant, and the like are added to the thermoplastic resin (B) and the thermoplastic resin (C) to obtain a resin composition for the sheet (Y). Specifically, after mixing with a ribbon blender, tumbler, Henschel mixer, etc., it can be obtained by kneading at a temperature equal to or higher than the resin flow start temperature using a Banbury mixer, a single screw or a twin screw extruder, etc. . In addition, a so-called master batch in which the thermoplastic resin (B) and the thermoplastic resin (C) and other compatibilizer (D), antioxidant, etc. are blended in high concentration in advance is prepared. The plastic resin (B) and the thermoplastic resin (C) can be mixed and adjusted to a desired concentration.

(Co-extrusion)
Next, after drying the resin composition for forming the reflective layer X and the resin composition for forming the reflective layer Y obtained in this manner, both are supplied to different extruders, and each is at a predetermined temperature or higher. Heat to melt.
Conditions such as the extrusion temperature vary depending on the thermoplastic resin used in each layer, but it is necessary to set in consideration of a decrease in molecular weight due to decomposition in any of the resins. For example, when the thermoplastic resin mentioned in the above example is used in each layer, the extrusion temperature of the reflective layer Y-forming resin composition is preferably 270 ° C. to 290 ° C.
Thereafter, the melted resin compositions are merged into a T-die for 2 types, 3 layers or 3 types and 5 layers, co-extruded in a laminated form from a slit-like discharge port of the T die, and solidified and solidified on a cooling roll. Form a sheet.

(Stretching)
Next, it is preferable to extend at least in a uniaxial direction.
The stretching direction may be either MD or TD, or both axes. However, in order to more effectively express the characteristics of the reflective film, it is preferable to stretch the film in both the MD and TD directions and to orient the film. By extending | stretching, in the resin composition A, the interface of an internal polyester resin and a filler peels, a space | gap is formed, and the light reflectivity of a film can be improved.

In addition, as a method of orienting the film in both the MD and TD directions, in addition to the above-described stretching method, for example, when forming a film by the T die casting method, by increasing the take-up speed (cast roll speed). Examples thereof include a method of stretching the MD after drafting to TD and a method of stretching the MD after drafting the MD by increasing the take-up speed when forming the film by the inflation method.
Among these, when considering the stability of film formation and the improvement of production efficiency, it is preferable to select a method of biaxially stretching the sheet formed by T-die casting as described above into MD and TD.

By biaxially stretching in this manner, for example, in the reflective layer Y, the dispersed phase (II) can be arranged and fixed in a substantially constant direction in the continuous phase (I). The difference in refractive index from (II) increases in the stretching direction, and the dispersed phase (II) is elongated in the stretching direction. Therefore, the dispersed phase (II) has a pseudo super multi-layer structure, and a reflective film having a gloss like a metal can be produced. Moreover, by biaxially stretching, the peeling area of the interface between the polyester resin (A) and the filler in the resin composition for forming the reflective layer X increases, and as a result, the light reflectivity of the film can be further improved. it can.
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.

As the stretching method, any of a stretching method, an inter-roll stretching method, a roll rolling method, and other methods may be adopted.
The stretching temperature is preferably a temperature within the range of the glass transition temperature (Tg) of the resin to (Tg + 50 ° C.). When the stretching temperature is within this range, stretching can be performed stably without breaking during stretching.
The draw ratio is not particularly limited. For example, it is preferably 2 to 9 times MD and / or TD, preferably 3 to 9 times MD and / or TD, particularly 4 to 7 times MD and / or TD. If the draw ratio is 2 times or more of MD and / or TD, the dispersed phase (II) in the reflective layer Y extends, and the peeled area at the interface between the polyester resin and the filler in the reflective layer (X) increases. Therefore, it is preferable. In addition, the difference in refractive index between the thermoplastic resin (B) forming the continuous phase (I) and the thermoplastic resin (C) forming the dispersed phase is increased, and the effect of improving the reflectance is obtained. Therefore, it is preferable. On the other hand, if it is 9 times or less, it is preferable because breakage of the film can be suppressed.

  The stretched sheet is preferably heat-treated to impart heat resistance and dimensional stability. The heat treatment temperature depends on the resin to be used, but when the resin composition listed in the above example is used, it is preferably 140 to 170 ° C, more preferably 150 to 160 ° C. The treatment time required for the heat treatment is preferably 1 second to 5 minutes.

<Application>
By using this reflective film, a liquid crystal display device, a lighting device, a decorative article, etc. comprising the reflective film can be configured.

<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 the present invention, the expression “main component” or “main component resin” 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. . Further, the content ratio of the main component is not specified, but unless otherwise specified, the main component is 50% by mass or more of the same kind of material in the composition (a filler if a filler, a resin if a resin). , Preferably 70% by mass or more, particularly preferably 90% by mass or more (including 100%).
However, when two or more kinds of materials constitute the main component, the ratio of each material in the composition may be 10% by mass or more, preferably 20% by mass or more, and particularly preferably 30% by mass or more.

Further, in the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise noted, “preferably greater than X” or “preferably with the meaning of“ X to Y ”. The meaning of “smaller than Y” is also included.
Furthermore, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. The intention of

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these, 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.

(1) Average refractive index difference between thermoplastic resin (B) and thermoplastic resin (C) Using an Atago Abbe refractometer, sodium D line (589 nm) as a light source, and according to JIS K7124, Examples and Comparison After measuring the average refractive index of each raw material used in the examples, the average refractive index difference was calculated.

(2) For the entire thickness of the thickness of each layer and reflection film obtained thickness occupancy ratio of the reflective layer X, then measure the plane unspecified was Thickness.
The thickness of each of the reflective layer Y and the reflective layer X, and the thickness occupancy ratio of the reflective layer X with respect to the total thickness of the reflective film were obtained by observing the cross section of the film obtained with a scanning electron microscope (SEM). Measured using a photograph.

(3) Porosity Measure the density of the film before stretching (denoted as “unstretched film density”) and the density of the film after stretching (denoted as “stretched film density”), and substitute it into the following equation. The porosity (%) of the film was determined. In addition, since the porosity of the reflective layer Y is zero, the porosity of the reflective layer X was calculated from the porosity of the reflective film and the thickness occupation ratio of the reflective layer X.
Porosity (%) = {(Unstretched film density−Stretched film density) / Unstretched film density} × 100

(4) Thickness-Void coefficient Each thickness obtained by the measurement in the above “(2) Thickness of each layer and the thickness occupation ratio of the reflective layer X” and each thickness obtained by the measurement in the above “(3) Porosity”; The thickness occupancy ratio and the porosity were calculated by substituting into the following formula (1).
(Formula 1) ··· Thickness-Void coefficient = Total film thickness (µm) × Film porosity (%) × Reflective layer X thickness occupancy (%)

(5) Reflectance Evaluation Method An integrating sphere is attached to a spectrophotometer (“U-3900H”, manufactured by Hitachi, Ltd.), and the reflectance when the alumina white plate is 100% is 0 over a wavelength range of 300 nm to 800 nm. The reflectance was obtained by measuring at intervals of 0.5 nm. Based on the measured values obtained, an average value in each wavelength region was calculated, and this value was defined as an average reflectance (%). Judging from the obtained results, the following criteria were used.
○ (good): The average reflectance at a wavelength of 700 nm to 400 nm is 95% or more.
X (poor): The average reflectance of wavelengths 700 nm to 400 nm is less than 95%.

(6) Transmittance evaluation method Integrating spheres were attached to a spectrophotometer ("U-3900H", manufactured by Hitachi, Ltd.), measured at 0.5 nm intervals over a wavelength range of 300 nm to 800 nm, and the transmittance (%) was measured. Obtained. Before the measurement, calibration was performed using an alumina white plate as a standard plate. Judging from the obtained results, the following criteria were used.
○ (good): The average transmittance at a wavelength of 700 nm to 400 nm is 3% or less.
X (poor): The average transmittance at a wavelength of 700 nm to 400 nm exceeds 3%.

(7) Luminance measurement method The liquid crystal part is taken out from the liquid crystal display ("Plus One Model: LCD8000V", manufactured by Century Co., Ltd.), and the film structure of the backlight unit is a brightness enhancement film / diffusion film 1 / prism film 1 / A display device that was recombined to be prism film 2 / diffusion film 2 / light guide plate / reflective film was produced. Using this reflective film as the reflective film of this display, the 9-point average luminance of the display at a position 45 cm away from the front of the display in a dark room was measured using a luminance meter ("CA-2000" manufactured by Konica Minolta Co., Ltd.). did.
○ (good): The 9-point average luminance value is 1500 cd / m 2 or more.
X (poor): The 9-point average luminance value is less than 1500 cd / m 2.

(8) Variable angle photometric measurement Using a goniophotometer GR200 (manufactured by Murakami Color Research Laboratory, automatic variable angle photometer), the normal direction is 0 ° with respect to the film surface, the incident angle is -45 °, and the sample Was incident on the light, and the light reflected on the film in the range of −60 ° to 90 ° was received. At this time, the maximum intensity of the obtained peak was normalized to 100%, and a graph of the horizontal bearing light angle and the vertical axis received relative peak intensity was prepared. From the obtained graph, the light receiving angle width where the light receiving relative peak intensity was 1% and 10% was calculated. A narrower light receiving angle width indicates stronger specular reflectivity. Judging from the obtained results, the following criteria were used.
○ (good): The light receiving angle width of the light receiving relative peak intensity of 10% is 10 ° or less.
X (poor): The light receiving angle width of the light receiving relative peak intensity of 10% is larger than 10 °.
○ (good): The light receiving angle width with a light receiving relative peak intensity of 1% is 60 ° or less.
X (poor): The light receiving angle width of the light receiving relative peak intensity 1% is larger than 60 °.

(9) Arithmetic mean roughness Ra
Conforms to JISB0601-2001.
First, a reflective film is cut out by 9 mm width x 6 mm length. The cut-out reflective film is attached to a carbon double-sided tape (Nisshin EM Co., Ltd.) on an observation holder. Thereafter, in order to prevent charging (charge-up) on the sample surface during observation, a conductive paste is placed at six locations around the sample, and Pt—Pd is deposited on the surface at 10 mA for 100 seconds. The sample was observed with ESA-2000 (manufactured by Elionix, non-contact type three-dimensional roughness meter) at a measurement magnification of 250 times (measurement range: 480 μm × 360 μm), and an arithmetic average roughness Ra was calculated.
○ (good): Arithmetic average roughness Ra is 0.15 μm or less.
X (poor): Arithmetic average roughness Ra exceeds 0.15 μm.

<Example 1>
As the polyester resin (A), a polyester resin having an alicyclic structure as a diol component (2,2,4,4-tetramethyl-1,3-cyclobutanediol 34.5 mol%, Tg: 117 ° C., hereinafter “A -1 ”) and titanium oxide (trade name“ KRONOS2450 ”, average particle diameter D50: 0.31 μm) manufactured by KRONOS Co., Ltd. at a mass ratio of 60:40, and then mixed with an antioxidant (ADEKA). 0.1 parts of PEP36A and AO-80) were added to 100 masses of mixture, and pelletized using a twin screw extruder heated at 270 ° C. to prepare a resin composition for forming a reflective layer X.

  Polyethylene naphthalate resin as thermoplastic resin (B) (average refractive index: 1.646, Tg: 118 ° C., Tm: 261 ° C., intrinsic viscosity 0.71 dl / g, weight average molecular weight 50,000, intrinsic birefringence: Positive, hereinafter referred to as “B-1”) and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride resin (average refractive index: 1.3547, Tm: 223 ° C.) as the thermoplastic resin (C) C-1 ”) are mixed at a mass mixing ratio of 70:30 and mixed sufficiently, and then pelletized using a twin screw extruder heated at 290 ° C. to form a reflective layer Y-forming resin composition. Was made.

The resin composition for forming the reflective layer X and the resin composition for forming the reflective layer Y are respectively supplied to the extruders A and B heated to 290 ° C., and melt-kneaded at 290 ° C. in each of the extruders. Merged into a T-die for seed 3 layers, extruded into a sheet shape so as to have a 3 layer configuration of reflective layer Y / reflective layer X / reflective layer Y, cooled and solidified with a cast roll having a roll temperature of 130 ° C., and laminated A sheet was obtained.
The obtained cast sheet was MD in a longitudinal stretching machine composed of a preheating roll, a stretching roll, and a cooling roll at a preheating temperature of 120 ° C., a stretching temperature of 133 ° C., and a cooling temperature of 60 ° C. due to the difference in roll speed between the stretching rolls The film was stretched 3 times.
Thereafter, the obtained longitudinally stretched film was stretched 5 times to TD at 130 ° C., stretched 130 ° C., and heat treated 130 ° C. by a tenter composed of a preheat zone, a stretch zone, and a heat treatment zone to obtain a reflective film. The passing times of the preheating zone, the stretching zone, and the heat treatment zone were each 32 seconds. The evaluation results of the obtained reflective film are shown in Table 1.

<Example 2>
In Example 1, a reflective film was obtained in the same manner as in Example 1 except that the draw ratio to TD was set to 4. The evaluation results of the obtained reflective film are shown in Table 1.

<Example 3>
In Example 1, a reflective film was obtained in the same manner as in Example 1 except that the stretching ratio to TD was 3 times. The evaluation results of the obtained reflective film are shown in Table 1.

<Example 4>
In Example 1, instead of the polyester resin A-1, a polyester resin having an alicyclic structure as a diol component (2,2,4,4-tetramethyl-1,3-cyclobutanediol 21 mol%, Tg: 107 Reflection in the same manner as in Example 1 except that MD stretching temperature is 120 ° C., preheating, stretching, and heat setting during TD stretching are each 120 ° C. A film was obtained. The evaluation results of the obtained reflective film are shown in Table 1.

<Example 5>
In Example 4, a reflective film was obtained in the same manner as in Example 4 except that the draw ratio to TD was set to 4. The evaluation results of the obtained reflective film are shown in Table 1.

<Comparative Example 1>
In Example 2, instead of the polyester-based resin A-1, a polyester-based resin having an alicyclic structure (spiroglycol 43.1 mol%, Tg: 109 ° C., hereinafter referred to as “A-3”) is used as the diol component. Example 2 except that the temperature of the extruder for supplying A-3 was 250 ° C., the cooling temperature during MD stretching was 70 ° C., and the preheating, stretching, and heat setting temperatures of TD stretching were 110 ° C. A reflective film was obtained in the same manner. The evaluation results of the obtained reflective film are shown in Table 1.

<Comparative Example 2>
In Comparative Example 1, a reflective film was obtained in the same manner as in Comparative Example 1 except that the temperatures of TD stretching preheating, stretching, and heat setting were 120 ° C. The evaluation results of the obtained reflective film are shown in Table 1.

From the above examples and the results of tests conducted by the inventors so far, the polyester-based resin (A) and the filler are included, and the reflective layer X having voids are disposed on both sides of the reflective layer X. As for the reflective film having a two-layer three-layer structure of the reflection layer Y and Y having a sea-island structure made of two types of resins (B) and (C), the brightness as well as the reflectance is satisfied if the following (Formula 1) is satisfied. It was found that can be improved sufficiently.
(Formula 1) .. Total thickness of film (μm) × Porosity of film (%) × Thickness occupation ratio of reflection layer X (%) ≧ 1300

In addition, when the reflective film obtained in Examples 1-5 was observed with the electron microscope, it was observed that the space | gap of the reflective layer X and the dispersed phase of the reflective layer Y were both flat structures.

Claims (11)

Reflective layer X containing only polyester-based resin (A) as a resin component and a filler and having voids, and two types of resins (B) and (C) disposed on both front and back sides of reflective layer X A method for producing a reflective film having a two-layer three-layer structure with a reflective layer Y, Y having a sea-island structure comprising:
After layering and integrating the reflective layers X and Y by coextrusion, uniaxially or biaxially stretched,
A method for producing a reflective film, wherein the produced reflective film satisfies the following (Equation 1) in terms of a thickness-void coefficient calculated by the left equation of the following (Equation 1).
(Formula 1) .. Total thickness of film (μm) × Porosity of film (%) × Thickness occupation ratio of reflection layer X (%) ≧ 1300 The method for producing a reflective film according to claim 1, wherein any one of the two resins (B) and (C) in the reflective layer Y is a crystalline polyester resin. Any one of the two resins (B) and (C) in the reflective layer Y has a glass transition temperature difference of 15 ° C. or less from the polyester resin (A) in the reflective layer X. It is a plastic resin, The manufacturing method of the reflective film of Claim 1 or 2 characterized by the above-mentioned. The method for producing a reflective film according to any one of claims 1 to 3, wherein the thickness of the entire reflective film is 40 to 300 µm, and the thickness occupation ratio of the reflective layer X is 50 to 95%. The method for producing a reflective film according to claim 1, wherein the film is stretched 2 to 9 times in MD and / or TD. The method for producing a reflective film according to claim 1, wherein the porosity of the reflective layer X is 5% to 70%. Method for producing a reflective film according to any one of claims 1 to 6, characterized in that a substantially zero porosity of the reflective layer Y. In the reflective layer X, the content of the filler and the polyester resin (A) (parts by weight) of a polyester resin (A): filler = 20: 80 to 80: characterized in that it is a 20 method for producing a reflective film according to any one of claims 1-7. The polyester resin (A), the manufacturing method of the reflecting film according to any one of claims 1-8, characterized in that the alicyclic structure is a perforated Surupo Riesuteru resin as the diol component. The polyester resin (A) has an alicyclic structure as the diol component, it claims 1-8 having a glass transition temperature (Tg), characterized in that a polyester resin is 100 to 130 ° C. The manufacturing method of the reflective film as described in any one of Claims 1-3. Reflective film according to any one of claims 1-10 said polyester resin (A), which is a polyester resin containing 5% to 50% of the diol component having an alicyclic structure in a molar ratio Manufacturing method.