JP2008233340A - Reflection film and reflection plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel reflection film increasing light reflectivity and dimensional stability under a heated condition. <P>SOLUTION: The reflection film is provided with a layer A containing a polyolefin based resin and a powdery filler and a layer B composed of an oriented polyester film. Excellent light reflectivity can be obtained from refractive scattering due to difference between refractive indices of the polyolefin based resin and the powdery filler in the layer A. Heat resistance of the whole reflection film is enhanced by layering the layer B having excellent heat resistance and the layer A and high excellent dimensional stability is exhibited even in use at a high temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reflective film and a reflective plate, and more particularly to a reflective film and a reflective plate used for a liquid crystal display device, a lighting fixture, a lighting signboard, and the like.

  Reflectors are used in many fields such as liquid crystal display devices, projection screens, planar light source members, lighting fixtures, and lighting signs. Recently, especially in the field of liquid crystal display devices, the size of the device and the advancement of display performance have progressed, and it has been demanded to improve the performance of the backlight unit by supplying as much light as possible to the liquid crystal. Further, more excellent light reflectivity has been demanded for a reflecting plate, particularly a reflecting film constituting the reflecting plate.

  In addition, when a reflector is incorporated in a large LCD TV, etc., it is used in a state where it is exposed to a light source for a long time. The

  Thus, as a reflective film capable of realizing excellent light reflectivity, a reflective film obtained by adding a fine powder filler such as titanium oxide to an aliphatic polyester resin has been proposed (Patent Document 1).

  In addition, as a reflective film with improved heat resistance, for example, in Patent Document 2, a layer containing an aliphatic polyester resin and a fine powder filler and a thermoplastic resin having a glass transition temperature of 80 or more are contained. A reflective film having a configuration in which layers are laminated is disclosed.

WO2004 / 104077 Japanese Patent Publication No. 2006-145914

  The present invention is intended to provide a new reflective film that can realize higher light reflectivity and is excellent in dimensional stability under a heating environment.

  This invention proposes the reflective film provided with A layer containing polyolefin resin and a fine powder filler, and B layer which consists of a stretched polyester film.

In general, the term “sheet” refers to a product that is thin by definition in JIS and generally has a thin thickness that is small instead of length and width. In general, a “film” is a thin flat product whose thickness is extremely small compared to the length and width and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll. (Japanese Industrial Standard JISK6900). 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.
Further, in the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X or more and Y or less” means “preferably larger than X and smaller than Y”. Is included.

The reflective film of the present invention can obtain excellent light reflectivity (also referred to as “reflectivity”) from refractive scattering due to the difference in refractive index between the polyolefin resin and the fine powder filler in the A layer. Moreover, by laminating the B layer and the A layer having excellent heat resistance, the heat resistance of the entire reflective film is increased, and excellent dimensional stability is exhibited even when used in a high temperature environment.
Therefore, the reflective film of the present invention is suitable as a reflective film for use in a reflective plate for a display such as a personal computer or a television, a lighting fixture, a lighting signboard, etc. Among them, excellent heat resistance such as a large-sized liquid crystal television is required. It is suitable as a reflective film for applications.

Embodiments of the present invention will be described below, but the scope of the present invention is not limited to the embodiments described below.
Note that 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 usually occupies at least 90% by mass, particularly preferably at least 90% by mass (including 100%).

  The reflective film according to the present embodiment (hereinafter referred to as “the present reflective film”) mainly has an A layer that plays a role of imparting light reflectivity to the reflective film, and a B that plays a role of mainly imparting heat-resistant dimensional stability to the reflective film. A reflective film comprising a layer.

[A layer]
A layer is a layer which consists of the resin composition A containing a polyolefin-type resin and a fine powder filler as a main component.

(Base resin)
Examples of the polyolefin-based resin as the base resin of the A layer (resin forming the main component of the A layer) include monoolefin polymers such as polyethylene and polypropylene, and copolymers thereof. Specific examples include polyethylene resins such as low density polyethylene, linear low density polyethylene (eg, ethylene-α-olefin copolymer), medium density polyethylene, and high density polyethylene, polybutylene resins, polypropylene, and ethylene-propylene copolymers. And polypropylene resins such as poly-4-methylpentene, polybutene, and ethylene-vinyl acetate copolymer. These resins may be used alone or in combination of two or more.
The polyolefin resin includes those produced using a multisite catalyst such as a Ziegler catalyst and those produced using a single site catalyst such as a metallocene catalyst.

  Further, a polyolefin-based thermoplastic elastomer obtained by dispersing and compounding ethylene / propylene rubber or the like in these polyolefin-based resins can also be used.

  Considering the moldability at the time of molding into a sheet shape and the heat resistance at the time of molding into a sheet shape, among the polyolefin resins, linear low density polyethylene resins such as ethylene-α-olefin copolymers, polypropylene, Preferred are polypropylene resins such as ethylene-propylene copolymer, propylene-butene copolymer, ethylene-propylene-butene terpolymer, ethylene-propylene-diene terpolymer, among which polypropylene resin, In particular, an ethylene-propylene copolymer such as polypropylene and an ethylene-propylene random copolymer is preferable.

  Further, from the viewpoint of improving the reflectance, polyolefins having a small refractive index are preferable, and it is particularly preferable to use a polyolefin resin having a refractive index of less than 1.52. For example, a polypropylene resin, a low density polyethylene resin, a polybutylene resin, polymethylpentene, and a mixture or copolymer thereof can be used. Among them, polypropylene having a refractive index of 1.48 is preferable.

Examples of the polypropylene resin include homopolypropylene resin, random polypropylene resin, block polypropylene resin, and propylene-ethylene rubber.
As a polymerization method for obtaining a polypropylene resin, known methods such as a solvent polymerization method, a bulk polymerization method, and a gas phase polymerization method can be employed. Moreover, as a polymerization catalyst, well-known catalysts, such as a titanium trichloride type catalyst, a magnesium chloride carrying | support catalyst, a metallocene catalyst, are employable, for example.

The melt flow rate (MFR) of the polyolefin resin is not particularly limited, but the MFR (JIS K7210, temperature: 230 ° C., load: 2.16 kg) is 0.5 g / 10 min or more, preferably 1 0.0 g / 10 min or more and 15 g / 10 min or less, preferably 10 g / 10 min or less. In the present invention, MFR is measured based on the method defined in ASTM D-1238.
If the melt flow rate of the polyolefin resin is too low, it is necessary to increase the extrusion temperature during melt molding. As a result, the reflectance may decrease due to yellowing due to oxidation of the polyolefin resin itself or thermal deterioration of titanium oxide. There is. On the other hand, when the melt flow rate of the polyolefin-based resin is too large, there is a possibility that the sheet production by melt molding becomes unstable.
Considering the moldability of the sheet, the MFR of the polyethylene resin is preferably about 0.2 to 7 g / 10 min (190 ° C., load 2.16 kg), and the MFR of the polypropylene resin is about 1 to 50 g / 10 min. (230 ° C., load 2.16 kg) is preferable.

  A commercially available product can also be used as the polyolefin-based resin as the base resin for the A layer. For example, “Novatech PP”, “WINTEC”, “Toughmer XR” (manufactured by Nippon Polypro), “Mitsui Polypro” (manufactured by Mitsui Chemicals), “Sumitomo Noblen”, “Tough Selenium”, “Excellen EPX” (manufactured by Sumitomo Chemical), Examples thereof include polypropylene resins such as “IDEMISU PP”, “IDEMITSU TPO” (manufactured by Idemitsu Kosan Co., Ltd.), “Adflex”, “Adsyl” (manufactured by Sun Allomer). In addition, these copolymers can be used individually or in mixture of 2 or more types, respectively.

(Fine powder filler of layer A)
Examples of the fine powder filler used in the A layer include organic fine powder and inorganic fine powder.

  Examples of the organic fine powder include at least one selected from cellulose powders such as wood powder and pulp powder, polymer beads, and polymer hollow particles.

Inorganic fine powders include calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, alumina, aluminum hydroxide, hydroxyapatite, silica, mica, talc And at least one selected from kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay, and the like.
In consideration of the light reflectivity of the resulting reflective film, those having a large refractive index difference from the base resin are preferable. That is, it is preferable that the inorganic fine powder has a large refractive index and that the reference is 1.6 or more. Specifically, calcium carbonate, barium sulfate, zinc oxide, or titanium oxide having a refractive index of 1.6 or more is preferably used, and titanium oxide having a high refractive index is particularly preferable. However, in view of long-term durability, barium sulfate which is stable against acids and alkalis is particularly preferable.
In addition, as a fine powder filler, you may use combining the inorganic fine powder illustrated as mentioned above, and organic fine powder. Further, different fine powder fillers can be used in combination, and for example, titanium oxide and other fine powder fillers may be used in combination.

  Titanium oxide has a significantly higher refractive index than other inorganic fine powders, and can significantly increase the difference in refractive index from the base resin, so it can be used in a smaller amount than when other fillers are used. Excellent reflectivity can be obtained. Further, by using titanium oxide, a reflective film having high reflectivity can be obtained even when the film is thin.

  As the titanium oxide used for the A layer, a crystalline titanium oxide such as anatase type or rutile type is preferable, and among them, a titanium oxide having a refractive index of 2.7 or more from the viewpoint of a large difference in refractive index from the base resin. Is preferred. In this respect, rutile type titanium oxide is preferable.

  Further, it is particularly preferable to use high-purity titanium oxide having high purity among titanium oxides. Here, high-purity titanium oxide means titanium oxide having a small light absorption ability for visible light, that is, titanium oxide having a small content of coloring elements such as vanadium, iron, niobium, copper, manganese, etc. Then, titanium oxide having a vanadium content of 5 ppm or less, preferably 4 ppm or less is referred to as high-purity titanium oxide.

Examples of high-purity titanium oxide include those produced by a chlorine process.
In the chlorine method process, rutile ore containing titanium oxide as a main component is reacted with chlorine gas in a high-temperature furnace of about 1000 ° C. to produce titanium tetrachloride first, and then this titanium tetrachloride is burned with oxygen, High purity titanium oxide can be obtained.
There is a sulfuric acid process as an industrial method for producing titanium oxide, but the titanium oxide obtained by this method contains a large amount of colored elements such as vanadium, iron, copper, manganese, niobium, etc. Absorption capacity increases. Therefore, it is difficult to obtain high-purity titanium oxide by the sulfuric acid method process.

  In order to improve the dispersibility in the base resin, the surface of the fine powder filler used in the A layer is a silicon compound, polyhydric alcohol compound, amine compound, fatty acid, fatty acid ester, etc. A surface-treated product can be used.

The fine powder filler, particularly titanium oxide, is preferably one whose surface is coated with an inert inorganic oxide. By coating the surface of titanium oxide with an inert inorganic oxide, the photocatalytic activity of titanium oxide can be suppressed, and the film can be prevented from being deteriorated by the photocatalytic action of titanium oxide.
As the inert inorganic oxide, it is preferable to use at least one selected from the group consisting of silica, alumina, and zirconia. If these inert inorganic oxides are used, the light resistance of the film can be enhanced without impairing the high light reflectivity exhibited when titanium oxide is used. Further, it is more preferable to use two or more kinds of inert inorganic oxides in combination, and among them, a combination in which silica is essential is particularly preferable.

  Further, in order to improve the dispersibility in the base resin, the surface of the inorganic fine powder, particularly titanium oxide, is at least one inorganic compound selected from the group consisting of a siloxane compound, a silane coupling agent and the like, a polyol It is also preferable that the surface treatment is performed with at least one organic compound selected from the group consisting of polyethylene glycol and the like.

The particle size of the fine powder filler is preferably 0.05 μm to 15 μm, more preferably 0.1 μm to 10 μm. When the particle size of the fine powder filler is 0.05 μm or more, the dispersibility in the base resin is good and a homogeneous film 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 film can be obtained.
However, when titanium oxide is used as the fine powder filler, the particle size is preferably 0.1 μm to 1.0 μm, and more preferably 0.2 μm to 0.5 μm. If the particle size of titanium oxide is 0.1 μm or more, the dispersibility in the base resin is good and a homogeneous film can be obtained. Moreover, if the particle diameter of a titanium oxide is 1.0 micrometer or less, the interface of base resin and a titanium oxide will be formed densely, and high light reflectivity can be provided to a reflective film.

  The content of the fine powder filler is preferably 20 to 70% by mass, and preferably 30 to 60% by mass with respect to the mass of the entire layer A in consideration of the light reflectivity, mechanical properties, productivity, etc. of the film. More preferably. If 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 light reflectivity can be imparted to the film. it can. Moreover, if content of a fine powder filler is 70 mass% or less, the mechanical property required for a film can be ensured.

(Other ingredients)
The A layer may contain a resin other than the polyolefin resin as described above within a range not impairing the effects of the polyolefin resin and the fine powder filler. In addition, hydrolysis inhibitors, antioxidants, light stabilizers, heat stabilizers, lubricants, dispersants, UV absorbers, white pigments, fluorescent enhancers, as long as the effects of polyolefin resins and fine powder fillers are not impaired. You may contain a whitening agent and another additive.

(Porosity)
The A layer preferably has voids inside. If it has voids, in addition to refractive scattering due to the difference in refractive index between the polyolefin resin and fine powder filler, the refractive index difference between the polyolefin resin and void (air), and between the fine powder filler and void (air). Reflectivity can also be obtained from refraction scattering due to.

In order to form voids in the A layer, for example, a film containing a fine powder filler may be stretched. This is because the stretching behavior of the base resin and the fine powder filler is different when stretched. That is, if stretching is performed at a stretching temperature suitable for the base resin, the matrix base resin is stretched, but the pulverized filler tends to remain as it is, so the interface between the base resin and the pulverized filler. Is peeled off to form voids. Accordingly, by effectively including the fine powder filler in a dispersed state, voids can be formed in the reflective film, and further excellent reflectivity can be imparted to the film.
Moreover, a foaming agent can be added to A layer and a space | gap can be formed in A layer by foaming.

The porosity of the A layer, that is, the ratio of the volume portion of the voids in the A layer is preferably 3% or more, particularly 3 to 35%, and more preferably 5 to 30%.
If the porosity is 3% or more, the effect of improving the reflectance can be obtained, and if the porosity is 35% or less, the mechanical strength of the film is ensured, the film breaks during film production, Durability such as heat resistance will not be insufficient during use.
In consideration of the improvement in reflectance, the porosity is more preferably 5% or more, and further preferably 7% or more within the above range.
In addition, the porosity at the time of extending | stretching a film can be substituted for the following formula, and the porosity of a film can be calculated | required (hereinafter the same).
Porosity (%) = {(density of film before stretching−density of film after stretching) / density of film before stretching} × 100

(Form)
The A layer may be a layer formed by laminating films, or a layer formed by forming a thin film of the molten resin composition by extrusion or coating (without forming a film). Further, when the film is formed and laminated, the film may be an unstretched film, a uniaxially or biaxially stretched film, but is preferably a biaxially stretched film.

[B layer]
B layer is a layer comprised from the stretched polyester film formed by extending | stretching the film obtained by forming into a film from resin which contains polyester-type resin as base resin (resin which makes the main component of B layer).

(Base resin)
Examples of the polyester resin as the base resin for the B layer include polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-o-oxybenzoate, poly-1,4-cyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalene. Examples thereof include carboxylate, and among them, polyethylene terephthalate is preferable from the viewpoint of water resistance, durability, chemical resistance, and the like.
The polyester resin may be used alone as a homopolyester, or may be used by blending two or more of the polyester resins exemplified above. Further, it may be a copolymer. For example, one or more diol components selected from diethylene glycol, neopentyl glycol, polyalkylene glycol and the like, adipic acid, sebacic acid, phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid And a copolymer obtained by copolymerizing one or more dicarboxylic acid components selected from the above.

(Other ingredients)
The B layer may contain a fine powder filler, a resin incompatible with the polyester resin (referred to as “incompatible resin”), or both.
By containing a fine powder filler or an incompatible resin, voids are formed in the B layer when biaxially stretched. Therefore, the fine powder filler or the incompatible resin and the base resin (polyester resin) Reflectivity can also be obtained from refractive scattering due to the refractive index difference between the base resin and the refractive index difference between the base resin and the gap, and also due to the refractive index difference between the fine powder filler or incompatible resin and the gap. it can.

  As the fine powder filler in this case, the same fine powder filler as used in the A layer can be used, and the preferred type is the same as that of the A layer.

  Examples of the incompatible resin include polyolefin resins such as polyethylene, polypropylene, polybutene, and polymethylpentene, and resins such as polystyrene, polyacrylate, polycarbonate, polyacrylonitrile, polyphenylene sulfide, and fluorine resin. Among these, polyolefin resins, particularly polypropylene and polymethylpentene having a low critical surface tension are preferable.

  The content of the finely powdered filler or incompatible resin in the B layer (the total content when both are contained) is determined in consideration of the light reflectivity, mechanical properties, productivity, etc. of the film. It is preferable that it is 10-60 mass% with respect to mass, and especially 20-50 mass%.

(Porosity)
When the B layer contains a fine powder filler or an incompatible resin, the B layer is formed from a stretched film, so that voids are formed in the B layer as described above.
Under the present circumstances, it is preferable that the porosity of B layer, ie, the ratio of the volume part of the space | gap which occupies in B layer, is 50% or less, and it is especially preferable that it is 5-50%. If the porosity is 50% or less, the mechanical strength of the film is ensured, and the film is not broken during film production, and durability such as heat resistance is not insufficient during use.
Further, taking into account the improvement in reflectance, the porosity is more preferably 20% or more, and particularly preferably 30% or more.

  When titanium oxide (high-purity titanium oxide) is used as the fine powder filler, high light reflectivity can be obtained regardless of the presence of voids inside the film. For example, even when there is no void, high light reflectivity can be obtained by using high-purity titanium oxide. This is presumably due to the fact that titanium oxide has a high hiding power as well as a large refractive scattering due to the refractive index difference between the biaxially stretched polyester film and the high-purity titanium oxide.

Further, a foaming agent can be added to the B layer, and voids can be formed in the B layer by this foaming.
Examples of the method of forming voids in the B layer by foaming include a method in which an organic or inorganic heat-decomposable foaming agent or volatile foaming agent is added to a polyester resin and foamed. Further, mention may be made of a method of foaming by introducing C0 ₂ and N ₂ in the supercritical state to the polyester resin.

[Laminated structure of the reflective film]
As the laminated structure of the present reflective film, it is only necessary to have an A layer and a B layer. For example, from the side irradiated with light (reflection use surface side), the A layer / B layer or the B layer / A layer It may be a film having a two-layer structure in which layers are laminated in order, or a laminated structure having a multilayer structure.

  Among these, a stacked structure including a two-layer structure in which layers A and B are stacked in this order from the light irradiation side (reflection use surface side) is preferable. Thus, when each layer is arrange | positioned, the A layer can fully exhibit the reflectivity, and can also enjoy the heat resistance of a B layer still more fully. Therefore, it is particularly preferable in applications such as large liquid crystal televisions that require dimensional stability under a heating environment at 80 ° C., for example.

Other layers may be provided in addition to the A layer and the B layer, and other layers may be interposed between the A layer and the B layer. For example, an adhesive layer may be interposed between the A layer and the B layer. Further, in addition to the A layer and the B layer, a layer containing a polyolefin-based resin and a fine powder filler as in the A layer, and a C layer having a different porosity from the A layer may be provided. By interposing such a C layer, the reflectance can be further improved and the dimensional stability can also be improved.
For example, A layer / C layer / B layer, A layer / B layer / C layer, C layer / A layer / B layer, C layer / B layer / A layer from the light irradiation side (reflection use surface side) , B layer / A layer / C layer, B layer / C layer / A layer are laminated in this order, A layer / C layer / A layer / B layer, C layer / A layer / C layer / B For example, a four-layer structure in which layers are stacked in order, or a stacked structure including multiple layers can be exemplified.
Above all, a layered structure in which A layer / C layer / B layer and C layer / A layer / B layer are laminated in this order from the light irradiation side (reflection use surface side), especially A layer / C layer / B layer A stacked structure in which the layers are stacked in this order is preferable. If the A layer / C layer is arranged in this order from the light irradiation side (reflection use surface side) and the B layer is arranged behind it, the light transmitted through the A layer can be reflected again by the C layer. In addition to being able to obtain even higher reflectivity, the heat resistance of the B layer can also be directly enjoyed. Therefore, for example, it is particularly preferable in applications such as large televisions that require dimensional stability under a heating environment at 80 ° C.
In the above case, an adhesive layer may be interposed between the A layer / C layer and the C layer / B layer. However, since the A layer / C layer has high heat-fusibility, it is not necessary to interpose an adhesive layer. .

[C layer]
C layer is a layer containing polyolefin resin and fine powder filler, and polyolefin resin and fine powder filler that can be used for C layer are polyolefin resin and fine powder filler that can be used for A layer. It is the same as the agent, and the preferred types are also the same. However, the composition does not have to be the same as that of the A layer.

  The content of the fine powder filler in the C layer is preferably 10 to 80% by mass with respect to the mass of the entire C layer, considering the light reflectivity, mechanical properties, productivity, etc. of the film. More preferably, it is 70 mass%. If the content of the fine powder filler is 10% by mass or more, the area of the interface between the base resin and the fine powder filler can be sufficiently secured, and the C layer has high light reflectivity for the film. Obtainable. Moreover, if content of a fine powder filler is 80 mass% or less, the mechanical property required for a film as C layer can be ensured.

The porosity of the C layer, that is, the proportion of the volume portion of the voids in the C layer may be lower than the porosity of the A layer, and is particularly preferably less than 3%. When the porosity is less than 3%, the mechanical strength of the film is ensured, and the film does not break during film production, and durability such as heat resistance does not become insufficient during use. In the present invention, the porosity when the C layer is unstretched is 0%.
On the other hand, when the C layer is interposed between the A layer and the B layer, the porosity of the A layer is preferably 3% or more, particularly 5% or more, and more preferably 7% or more.

C layer should just be formed without extending | stretching from the resin composition containing polyolefin resin and a fine powder filler. For example, it can also be formed from an unstretched film obtained by melting the resin composition to form a film. Further, the resin composition can be melted to form a thin film (without forming a film) by extrusion or coating.
On the other hand, when the C layer is interposed between the A layer and the B layer, the A layer is formed from a stretched film obtained by forming and stretching a resin composition containing a polyolefin resin and a fine powder filler, for example. And it is preferable to manufacture so that the porosity can be raised.

(Adhesive layer)
As the resin constituting the adhesive layer, a soft styrene resin, a resin obtained by modifying a styrene resin, a resin having a functional group with a polar group, a soft polyester resin, a copolyester resin, a modified polyolefin, an aliphatic Based hydrocarbon resins and petroleum resins. Moreover, the mixture which mixed these 2 or more types can also be used.

Said soft styrene-type resin is a styrene-type elastomer resin which contains styrene 10 mass% or more, More preferably 10-40 mass%, and contains an elastomer component.
Examples of the resin suitably used as the elastomer component include butadiene, isoprene, 1,3-pentadiene and the like.
Specific examples of the styrene-based elastomer resin include styrene-butadiene elastomer (SBS) and styrene-isoprene elastomer (SIS).
Further, a hydrogenated styrene elastomer hydrogenated to SBS or SIS, for example, a commercially available hydrogenated styrene elastomer such as “Tuff Tech H Series” (Asahi Kasei Chemicals) can be suitably used.

As a resin obtained by modifying the above styrene resin, or a resin having a functional group to which a polar group is added, a block copolymer or graft copolymer having a high affinity with a polyester resin, or a reactable polarity Examples thereof include a block copolymer or a graft copolymer having a group and a compatible part with a styrene resin.
Here, the polar group having high affinity or reaction with the polyester resin refers to a functional group having high affinity or reaction with the polar group of the polyester resin, specifically an acid anhydride group, Carboxylic acid group, carboxylic acid ester group, carboxylic acid chloride group, carboxylic acid amide group, carboxylic acid group, sulfonic acid group, sulfonic acid ester group, sulfonic acid chloride group, sulfonic acid amide group, sulfonic acid group, epoxy group , Amino group, imide group, oxazoline group and the like.
The one having a compatible part with a styrene resin refers to one having a chain having an affinity with styrene, specifically a styrene chain, a styrene copolymer segment, etc. as a main chain, block or Examples thereof include a graft chain and a random copolymer containing a styrene monomer unit.
Examples of the copolymer include styrene-butyl acrylate copolymer, styrene-butadiene block copolymer (SBS), hydrogenated styrene-butadiene block copolymer (SBS), styrene-isoprene block copolymer (SIS), Examples thereof include a rubber obtained by modifying a hydrogenated styrene-isoprene block copolymer (SEPS), a styrene-ethylene-propylene copolymer, a styrene-ethylene-butylene copolymer, etc. with a modifier having a polar group. A block copolymer here contains a pure block, a random block, a tapered block, etc., and it does not specifically limit about the form of copolymerization. Further, the block unit may be overlapped by any number of repeating units. Specifically, in the case of a styrene-butadiene block copolymer, the block unit may be repeated many times like a styrene-butadiene-styrene-butadiene block copolymer.
Further, as the modified styrene resin, a modified styrene elastomer containing a large amount of an elastomer component is preferably used.
Of these, modified SEBS and SEPS are particularly preferred. Specific examples include maleic anhydride-modified SEBS, maleic anhydride-modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS. The modified styrene (based elastomer) referred to here may be used singly or in combination of two or more.
Specific products include hydrogenated styrenic thermoplastic elastomers modified with highly reactive functional groups such as “Tuff Tech M1943” (Asahi Kasei Chemicals), “Polar Group Modified Dynalon” (JSR) and Epoxy. And thermoplastic elastomer “Epofriend” (Daicel Chemical).
Examples of the resin having a functional group to which a polar group has been added include an ethylene copolymer with GMA having an epoxy group and an ethylene terpolymer “bond first” (Sumitomo Chemical).

The above-mentioned modified polyolefin refers to a resin whose main component is a polyolefin modified with an unsaturated carboxylic acid or an anhydride thereof, or a silane coupling agent.
Examples of the unsaturated carboxylic acid or its anhydride include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, citraconic acid, citraconic anhydride, itaconic acid, itaconic anhydride, or monoepoxy compounds of these derivatives and the above acids. Ester compounds, and a reaction product of a polymer having a group capable of reacting with these acids in the molecule and an acid. These metal salts can also be used. Among these, maleic anhydride is more preferably used.
Examples of the silane coupling agent include vinyltriethoxysilane, methacryloyloxytrimethoxysilane, and γ-methacryloyloxypropyltriacetyloxysilane.
In order to produce the modified polyolefin as described above, for example, these modified monomers can be copolymerized in the stage of polymerizing in advance, or these modified monomers are copolymerized with the graph once polymerized. You can also.
Moreover, modification | denaturation can use these modified | denatured monomers individually or in combination, and the content is 0.1-5 mass% suitably. Of these, those modified by grafting can be preferably used.
Specifically, commercially available products such as trade names “Admer” (Mitsui Chemicals) and “Modic” (Mitsubishi Chemical) can be suitably used. These copolymers can be used alone or in admixture of two or more.

Examples of the aliphatic hydrocarbon resin or petroleum resin include alicyclic petroleum resin from cyclopentadiene or a dimer thereof, and aromatic petroleum resin from C9 component.
Examples of terpene resins include terpene resins and terpene-phenol resins from β-pinene, and examples of rosin resins include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.
Such hydrocarbon resins are known to exhibit relatively good compatibility when mixed with polyolefin resins, etc., but the color point, thermal stability, and hydrogen point or derivative from compatibility It is preferable to use it.
Specifically, Mitsui Chemicals' product names “Hilets” and “Petrogin”, Arakawa Chemical Industries' product name “Arcon”, Yashara Chemicals' product name “Clearon”, Idemitsu Petrochemical Co., Ltd. ) And trade name “Escollets” of Tonex Co., Ltd., and other commercial products can be used.

[Thickness]
In the present reflective film, the ratio of the A layer is 20 to 90%, preferably 40 to 80%, and more preferably 50 to 70% in terms of the thickness ratio to the thickness of the entire reflective film. If it is 20% or more, light reflectivity can be sufficiently imparted, and if it is 90% or less, heat resistance can be imparted.
In addition, when forming C layer, the ratio for which the total thickness of A layer and C layer accounts is 20 to 90% by the thickness ratio with respect to the thickness of the whole reflection film, Preferably it is 40 to 80%, More preferably, it is 50. It is preferable to be in the range of ˜70%.

The thickness of the entire reflective film is not particularly limited, but is usually 30 μm to 1500 μm, and is preferably in the range of about 50 μm to 1500 μm in consideration of handling in practical use.
For example, as a reflective film for small and thin reflectors, the thickness is preferably 30 μm to 200 μm. If a reflective film having such a thickness is used, it can also be used for small and thin liquid crystal displays and the like such as notebook computers and mobile phones.
On the other hand, as a reflective film and a reflective plate for a large-sized liquid crystal television or the like, the thickness is preferably 75 μm to 1500 μm.

[Reflectance]
As for the reflectance of the present reflective film, the reflectance of the film surface with respect to light having a wavelength of 550 nm as measured from the reflective use surface side is preferably 95% or more, and more preferably 97% or more. If the reflectivity is 95% or more, the reflective film exhibits good reflective properties, and a liquid crystal display or the like incorporating this reflective film has a clear color with no yellowish screen.

[Production method]
For example, (1) A film constituting the A layer and a film B constituting the B layer are respectively prepared or prepared, and the film A and the film B are laminated through an adhesive layer. Thus, a reflective film can be manufactured. Further, (2) a reflective film can be produced by thermally fusing film A and film B without using an adhesive. (3) A reflective film can be produced by forming an A layer made of the resin composition A on the film B. However, it is not limited to these manufacturing methods.
First, the manufacturing method (1) will be described in detail.

(Preparation of film A for A layer formation)
A resin composition A may be prepared by blending a polyolefin resin and a fine powder filler, and the resin composition A may be melted to form a film, and then stretched as necessary to produce the film A.
Hereinafter, the production method of the film A will be described in detail.

First, a resin composition A is prepared by blending a fine powder filler and, if necessary, other additives into a polyolefin resin.
Specifically, after adding a fine powder filler to the polyolefin resin and mixing with a ribbon blender, tumbler, Henschel mixer, etc., using a Banbury mixer, a single screw or a twin screw extruder, etc., a temperature above the melting point of the base resin. The resin composition A is obtained by kneading.

  In addition, the resin composition A can also be obtained by adding a predetermined amount of the polyolefin resin and the fine powder filler with separate feeders or the like. In addition, a so-called master batch in which a fine powder filler is blended with a polyolefin resin at a high concentration in advance is prepared, and the master batch and the polyolefin resin are mixed to obtain a resin composition A having a desired concentration. it can.

Next, the resin composition A thus obtained is melted to form a film A.
For example, the resin composition A is dried, supplied to an extruder, heated to a temperature equal to or higher than the melting point of the base resin, and melted. At this time, the resin composition A may be supplied to the extruder without drying, but if not dried, it is preferable to use a vacuum vent during melt extrusion.
Conditions such as the extrusion temperature are preferably set in consideration of a decrease in molecular weight due to decomposition.

  After the extrusion, for example, the molten resin composition A is extruded from the slit-shaped discharge port of the T die, and is solidified by being adhered to the cooling roll to form a cast sheet (unstretched state). obtain.

The obtained unstretched film A is preferably stretched 1.1 times or more in at least a uniaxial direction as necessary.
By stretching, a void with a fine powder filler as a core is formed inside the film, and an interface between the base resin and the void and an interface between the void and the fine powder filler are formed, and refraction generated at each of these interfaces. Since the effect of scattering increases, the light reflectivity of the film can be further enhanced.

  The stretching temperature at the time of stretching is preferably a temperature within the range from the glass transition temperature (Tg) of the base resin to the melting point (Tm) or less. If the stretching temperature is within this range, the film can be stably stretched without breaking during stretching, and the stretching orientation becomes high, and as a result, the porosity increases, so that the film has a high reflectance. Can be obtained.

The unstretched film A is more preferably biaxially stretched.
By biaxially stretching, the porosity can be further increased, and the light reflectivity of the film can be further enhanced. Further, when the film is only uniaxially stretched, the formed voids are only in a fibrous form extending in one direction, but by biaxially stretching, the voids are in a disk-like form stretched in both the vertical and horizontal directions. That is, by biaxially stretching, the peeling area at the interface between the base resin and the fine powder filler is increased, and the whitening of the film proceeds. As a result, the light reflectivity of the film can be enhanced. Furthermore, since biaxial stretching eliminates anisotropy in the shrinking direction of the film, the heat resistance and mechanical strength of the film can be improved.

The order of stretching when biaxially stretching is not particularly limited. For example, simultaneous biaxial stretching or sequential stretching may be used.
Also, the stretching method is not particularly limited. For example, after melt film formation, the film may be stretched in the MD (film take-up direction) by roll stretching, and then stretched in the TD (direction perpendicular to the MD) by tenter stretching, or tubular stretching, etc. Biaxial stretching may be performed by However, when heat treatment is performed after stretching, tenter stretching is preferred.

The stretching ratio in the case of uniaxial stretching or biaxial stretching is preferably determined as appropriate according to the film composition, stretching means, stretching temperature, and desired product form. As a guideline, the area magnification is preferably 7 times or more, more preferably 25 times or more.
If the cast sheet is stretched so that the area magnification is 7 times or more, a porosity of 3% or more can be realized inside the film, and a porosity of 7% or more is realized by stretching it to 25 times or more. be able to.

Further, in order to impart heat resistance and dimensional stability to the obtained film A, it is preferable to perform heat treatment (also referred to as heat setting treatment).
The heat treatment temperature is preferably 90 to 160 ° C, and more preferably 110 to 140 ° C.
The treatment time required for the heat treatment is preferably 1 second to 5 minutes.

(Preparation of film B for forming B layer)
After adding polyester resin and additives such as fine powder filler and incompatible resin as necessary to prepare resin composition B, the resin composition B is melted to form a film. The film B may be produced by biaxial stretching.
Hereinafter, the production method of this film B will be described in detail.

  First, other additives such as fine powder fillers and incompatible resins are blended into the polyester resin, if necessary, and mixed with a ribbon blender, tumbler, Henschel mixer, etc., and then a Banbury mixer, uniaxial or biaxial Using an extruder or the like, the resin composition B is obtained by kneading at a temperature equal to or higher than the melting point of the base resin (for example, 270 ° C. to 300 ° C. in the case of polyethylene terephthalate).

  In addition, you may make it obtain the resin composition B by adding predetermined amounts of polyester-type resin and additives, such as a fine powder filler and an incompatible resin, with a separate feeder. In addition, a so-called master batch in which additives such as fine powder fillers and incompatible resins are blended in a high concentration in a polyester resin is prepared in advance, and this master batch and the polyester resin are mixed to obtain a desired concentration. The resin composition B may be used.

Next, the resin composition B is dried, supplied to an extruder, heated to a temperature equal to or higher than the melting point of the resin, and melted.
At this time, the resin composition B may be supplied to the extruder without drying, but in this case, it is preferable to use a vacuum vent during melt extrusion.

The melted resin composition B is extruded from the slit-shaped discharge port of the T die, and is closely adhered to the cooling roll to form a cast sheet (unstretched state).
In this case, the extrusion temperature is preferably in the range of 270 ° C. to 300 ° C., for example, in the case of polyethylene terephthalate.

Subsequently, the obtained cast sheet can be biaxially stretched to obtain a film B.
The stretching temperature at the time of stretching is preferably a temperature in the range of about the glass transition temperature (Tg) of the base resin to (Tg + 50 ° C.). For example, in the case of polyethylene terephthalate, it is 80 to 120 ° C. preferable. When the stretching temperature is within this range, it is preferable that the stretching temperature does not break during stretching.

Biaxial stretching is preferably performed at an area magnification of 2 times or more, and more preferably 9 times or more.
By biaxial stretching to 2 times or more in area magnification, anisotropy disappears in the shrinking direction of the film. Furthermore, the mechanical strength of the film can be increased. Moreover, when a fine powder filler is mix | blended, since the porosity becomes high and the light reflectivity of a film can also be improved further, it is preferable.

The order of stretching when biaxially stretching is not particularly limited. For example, simultaneous biaxial stretching or sequential stretching may be used.
Also, the stretching method is not particularly limited. For example, after melt film formation, the film may be stretched in the MD (film take-up direction) by roll stretching, and then stretched in the TD (direction perpendicular to the MD) by tenter stretching, or tubular stretching, etc. Biaxial stretching may be performed by However, when heat treatment is performed after stretching, tenter stretching is preferred.

The film B is preferably subjected to heat treatment after biaxial stretching in order to impart heat resistance and dimensional stability.
In the case of polyethylene terephthalate, for example, the heat treatment temperature is preferably 150 ° C. to 230 ° C.
The treatment time required for the heat treatment is preferably 1 second to 5 minutes.

(Lamination of film A and film B)
The film A and the film B produced as described above may be bonded through an adhesive layer (including an adhesive and an adhesive sheet).

  Specifically, for example, an adhesive such as polyester, polyurethane, and epoxy can be applied to the adhesive surface of the film B, and the film A can be bonded. In this method, for example, a commonly used coating equipment such as a reverse roll coater or a kiss roll coater is used, and the film is bonded to the surface of the film B so that the adhesive film thickness after drying is about 2 μm to 4 μm. Apply the agent. Next, the coated surface was dried and heated with an infrared heater and a hot air heating furnace, and the film B was directly coated with the adhesive of the film B using a roll laminator while maintaining the surface of the film B at a predetermined temperature. A reflective film may be obtained by covering the surface and cooling.

Further, the film A and the film B may be heat-sealed without using an adhesive.
As an example of the method of heat-sealing, after superimposing film A and film B, the film A and film B are heat-sealed by heating and pressurizing with a heating roll or a press, and this reflection film is made. Can be manufactured.

Furthermore, the reflective film can be produced by forming an A layer made of the resin composition A on the film B.
Examples of the film forming method include, but are not particularly limited to, methods such as extrusion lamination, sand lamination, and coextrusion.

  As an example of an extrusion laminating method, when a molten resin composition A is extruded from a slit-like discharge port of a T die and solidified by a cooling roll to form a cast sheet, a film B is formed on at least one side of the sheet. In addition, a method of obtaining a reflective film by pressing and cooling (that is, extrusion laminating) the extruded film A (cast sheet) and the film B between a cooling roll and a nip roll can be exemplified. .

  At this time, the adhesive layer resin is put into another extruder and melted, and the resin composition A and the adhesive resin are co-extruded to adhere and solidify to the cooling roll, and at the same time, the film B is attached to the cooling roll. A reflective film can also be obtained by pressing and cooling the A layer and the B layer between the nip roll and the nip roll.

  The reflective film obtained as described above may be further heat-treated. Heat treatment is preferable because crystallization of the resin forming the film can be promoted.

(Manufacturing method when providing C layer)
Next, as an example of a production method when a C layer is provided in addition to the A layer and the B layer, a production method of a film formed by laminating in the order of A layer / C layer / B layer will be described.

The film A for forming the A layer may be prepared by melting the resin composition A to form a film and stretching the film, preferably biaxially stretching, as described above.
The film B for forming the B layer may be prepared as described above.
Then, a resin composition C prepared in the same manner as the resin composition A (however, the composition may be different from the resin composition A) is melted and extruded, and at the same time, a film is sandwiched from both sides By laminating A and film B on top of each other, a film having a laminated structure of A layer / C layer / B layer can be produced.

  Further, the C layer and the adhesive layer are coextruded so as to be, for example, an adhesive layer / C layer / adhesive layer, and the above-mentioned film A and film B are laminated from both sides and laminated, whereby the A layer / A film having a laminated structure of (layer) / C layer / (adhesive layer) / B layer can be produced. Specifically, the resin composition C is charged into a melt-kneading extruder and melted, while the adhesive layer resin is charged into a separate extruder and melted, and each molten resin composition is slit into a T-die. The film A and the film B are respectively bonded to the adhesive layer at the same time as forming a laminated sheet of two types and three layers of adhesive layer / C layer / adhesive layer by extruding from the discharge port of the adhesive By laminating, a film having a laminated structure of A layer / (adhesive layer) / C layer / (adhesive layer) / B layer can be produced.

  Also, a resin composition C prepared in the same manner as the resin composition A (however, the composition may be different from that of the resin composition A) is melted to form an unstretched film C for forming a C layer. A film having a laminated structure of A layer / (adhesive layer) / C layer / (adhesive layer) / B layer is prepared by laminating and laminating the film A and film B with an adhesive. can do.

  Furthermore, the C layer can also be formed by applying the molten resin composition C on the film A or the film B, or by extruding it.

[Usage]
The present reflective film is particularly useful when used as a reflective film for a large-sized liquid crystal television or the like in the form of a film, but can also be suitably used as a reflective plate covered with a metal plate or a resin plate. This reflecting plate is useful as a reflecting plate used for liquid crystal display devices such as a liquid crystal display, lighting fixtures, lighting signs, and the like.
Below, an example is given and demonstrated about the manufacturing method of such a reflecting plate.

As a method of coating the reflective film on a metal plate or a resin plate, a method using an adhesive, a method of heat-sealing without using an adhesive, a method of bonding via an adhesive sheet, a method of extrusion coating, etc. There is no particular limitation. For example, apply an adhesive such as polyester, polyurethane, or epoxy on the surface of the metal plate or resin plate (collectively referred to as “metal plate”) to which the reflective film is to be bonded, and bond the reflective film. Can do.
In this method, commonly used coating equipment such as a reverse roll coater and 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 film 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 reflective film is immediately coated and cooled using a roll laminator, and reflected. You can get a board.
In this case, when the surface of the metal plate or the like is held at 210 ° C. or lower, the light reflectivity of the reflecting plate can be maintained high. In addition, it is preferable that the surface temperature of a metal plate etc. is 160 degreeC or more.

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.
In addition, the measured value and evaluation which are shown to an Example were performed as shown below. Here, the film take-up (flow) direction is indicated by MD, and its orthogonal direction is indicated by TD.

(Measurement and evaluation method)
(1) Niobium content in titanium oxide (ppm)
The niobium content was measured based on JIS M-8321 “Titanium Ore-Niobium Determination Method”. That is, 0.5 g of a sample was weighed, and this sample was transferred to a nickel crucible containing 5 g of a molten mixture [sodium hydroxide: sodium peroxide = 1: 2 (mass ratio)] and stirred. The surface of the sample was covered with 2 g of anhydrous sodium carbonate, and the sample was heated and melted in a crucible to form a melt. The melt was allowed to cool in the state of being put in a crucible, and then 100 mL of warm water and 50 mL of hydrochloric acid were added to the melt to dissolve it, and water was further added to make up to 250 mL. This solution was measured with an ICP emission spectrometer, and the niobium content was determined. However, the measurement wavelength was set to 309.42 nm.

(2) Average particle diameter of titanium oxide Using a powder specific surface measuring instrument (transmission method) of model “SS-100” manufactured by Shimadzu Corporation, 3 g of sample in a sample cylinder having a cross-sectional area of 2 cm ² and a height of 1 cm. The air permeation time of 20 cc was measured with a 500 mm water column, and the average particle diameter of titanium oxide was calculated from this.

(3) Reflectance (%)
An integrating sphere was attached to a spectrophotometer (“U-4000”, manufactured by Hitachi, Ltd.), and the reflectance with respect to light having a wavelength of 550 nm was measured. In that case, light was irradiated from the reflective use surface side of the reflective film. Before the measurement, the photometer was set so that the reflectance of the alumina white plate was 100%.

(4) Thermal shrinkage A marked line with a width of 200 mm was put in each of MD and TD of the reflective film, and cut out as a sample. The cut sample was placed in a hot air circulating oven at a temperature of 80 ° C. and held for 3 hours, and then the amount of shrinkage of the sample between the marked lines was measured. The ratio of the shrinkage amount to the original size (200 mm) between the sample marked lines before putting in the oven was defined as the thermal shrinkage rate (%).

(5) Heat resistance evaluation The fixed frame of the reflective sheet incorporated in the backlight of 42-inch liquid crystal television made from LPL was used. A reflective film was attached to this fixed frame in the same manner as it was actually attached to a liquid crystal television, and after heating at 80 ° C. for 3 hours, the appearance of the reflective film was observed with the naked eye and evaluated based on the following criteria. .

(Evaluation criteria)
A: No change is observed in the appearance of the film after heating.
B: Irregularities having a height of less than 0.5 mm that cannot be measured are seen on the heated film, but there are no practical problems such as uneven brightness.
C: Concavities and convexities with a height of less than 1 mm are observed on the heated film.
D: Unevenness with a height of 1 mm or more is observed in the heated film.

[Example 1]
Titanium oxide was obtained by a so-called chlorine process in which titanium halide was vapor-phase oxidized. The surface of the obtained titanium oxide was coated with 3% by mass and 0.3% by mass, respectively, in the order of alumina and silane coupling agent. The average particle size was 0.28 μm, the niobium content was 370 ppm, and the vanadium content was 4 ppm.

  A pellet of an ethylene-propylene random copolymer (MFR: 7 g / 10 min, refractive index: 1.50) and the above titanium oxide were mixed at a mass ratio of 30:70 to obtain a mixture. This mixture was pelletized using a twin screw extruder to produce a so-called master batch. This master batch and an ethylene-propylene random copolymer (MFR: 7 g / 10 min, refractive index: 1.50) were mixed at a mass ratio of 70:30 to prepare a resin composition A. Thereafter, the resin composition A is supplied to an extruder heated to 200 ° C., and is kneaded at 200 ° C. using this extruder, and then the molten resin composition A is extruded into a sheet form from a T die, After cooling and solidification, a film A having a thickness of 200 μm was formed.

  Next, as a film B, a biaxially stretched polyester film (Diafoil S100-100: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., refractive index: 1.58) having a thickness of 100 μm is used, and is commercially available on one side of the film B. The polyurethane adhesive is applied so that the adhesive film thickness after drying is about 3 μm, and then the coated surface is dried and heated by an infrared heater and a hot air heating furnace, and immediately using a roll laminator, After the film A was laminated and adhered on the adhesive-coated surface, the film was cooled to obtain a reflective film having a thickness of 300 μm having a two-layer structure (A layer / B layer from the reflective use surface side).

  With respect to the obtained reflective film, the reflectance, shrinkage rate, and heat resistance were measured and evaluated, and the results are shown in Table 1.

[Example 2]
A pellet of polypropylene (MFR: 5 g / 10 min, refractive index: 1.49) and the above titanium oxide were mixed at a mass ratio of 30:70 to obtain a mixture. This mixture was pelletized using a twin screw extruder to produce a so-called master batch. This master batch and polypropylene (MFR: 5 g / 10 min, refractive index: 1.49) were mixed at a mass ratio of 70:30 to prepare a resin composition A. Thereafter, the resin composition A is supplied to an extruder heated to 200 ° C., and is kneaded at 200 ° C. using this extruder, and then the molten resin composition A is extruded into a sheet form from a T die, After cooling and solidification, a film A having a thickness of 200 μm was formed.

  Next, in the same manner as in Example 1, a reflective film having a thickness of 300 μm having a two-layer structure (A layer / B layer from the reflective use surface side) was obtained.

  The obtained film was measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 3]
Titanium oxide was obtained by a so-called chlorine process in which titanium halide was vapor-phase oxidized. The surface of the obtained titanium oxide was coated with 3% by mass and 0.3% by mass, respectively, in the order of alumina and silane coupling agent. The average particle size was 0.28 μm, the niobium content was 370 ppm, and the vanadium content was 4 ppm.

A pellet of an ethylene-propylene random copolymer (MFR: 7 g / 10 min, refractive index: 1.50) and the above titanium oxide were mixed at a mass ratio of 30:70 to obtain a mixture. This mixture was pelletized using a twin screw extruder to produce a so-called master batch.
This master batch and polypropylene (MFR: 5 g / 10 min, refractive index: 1.49) were mixed at a mass ratio of 43:57 to prepare a resin composition A. Thereafter, the resin composition A is supplied to an extruder heated to 200 ° C., and is kneaded at 200 ° C. using this extruder, and then the molten resin composition A is extruded into a sheet form from a T die, A film was formed by cooling and solidification, and the obtained film was simultaneously biaxially stretched 5 times to MD and 5 times to TD at a temperature of 155 ° C. to obtain a film A having a thickness of 75 μm.

  As film B, a biaxially stretched polyester film (Diafoil S100-100: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., refractive index: 1.58) having a thickness of 100 μm was prepared.

As the C-layer resin composition C, polypropylene (MFR: 5 g / 10 min, refractive index: 1.49) and the above titanium oxide were mixed at a mass ratio of 60:40 to prepare a resin composition C.
Further, a styrene thermoplastic elastomer (“Dynalon 8630” manufactured by JSR) was used as the adhesive resin.
The resin composition C and the adhesive resin are each melt-kneaded at a set temperature of 200 ° C. using separate twin screw extruders, merged into a T-die for two types and three layers, and extruded at a cast temperature of 90 ° C. The film (adhesive layer / C layer / adhesive layer) is bonded to the film A from the cast surface side and the film B from the non-cast surface side while nip-rolling to form a three-layer structure (A layer / C Layer / B layer) having a thickness of 400 μm (A layer has a porosity of 8% and C layer has a porosity of 0% (unstretched)).

  With respect to the obtained reflective film, the reflectance, shrinkage rate, and heat resistance were measured and evaluated, and the results are shown in Table 1.

[Comparative Example 1]
A pellet of an ethylene-propylene random copolymer (MFR: 7 g / 10 min, refractive index: 1.50) and the above titanium oxide were mixed at a mass ratio of 30:70 to obtain a mixture. This mixture was pelletized using a twin screw extruder to produce a so-called master batch. This master batch and an ethylene-propylene random copolymer (MFR: 7 g / 10 min, refractive index: 1.50) were mixed at a mass ratio of 70:30 to prepare a resin composition. Thereafter, the resin composition is supplied to an extruder heated to 200 ° C. and kneaded at 200 ° C. using the extruder, and then the molten resin composition is extruded into a sheet form from a T-die and cooled. Solidified to form a 200 μm A layer film.

  About the obtained A layer film, ie, the A layer film which is a single layer film without being laminated with the B layer film, the reflectance, shrinkage rate, and heat resistance of the film are measured and evaluated. Table 1 shows.

[Comparative Example 2]
A pellet of polyethylene terephthalate (refractive index: 1.58) and the titanium oxide were mixed at a mass ratio of 60:40 to obtain a resin composition. This resin composition is melt-cast at 280 ° C., stretched 2.5 times to MD at 90 ° C. and then stretched 2.5 times to TD at 90 ° C., and then biaxially stretched to form B layer. A film was obtained.

  About the obtained B layer film, that is, the B layer film which is a single layer film without being laminated with the A layer film, the reflectance, shrinkage rate, and heat resistance of the film are measured and evaluated. Table 1 shows.

Claims (14)

  A reflective film comprising an A layer containing a polyolefin-based resin and a fine powder filler, and a B layer made of a stretched polyester film.   A layer containing a polyolefin resin and a fine powder filler and having a porosity of 3% or more; a C layer containing a polyolefin resin and a fine powder filler and having a porosity lower than that of the A layer; The reflective film of Claim 1 provided with B layer which consists of a stretched polyester film.   The A layer is a layer formed from a stretched film obtained by forming and stretching a resin composition containing a polyolefin resin and a fine powder filler, and the C layer is a polyolefin resin and a fine powder filler. The reflective film according to claim 2, wherein the reflective film is a layer formed without stretching from a resin composition comprising   4. The reflective film according to claim 1, wherein the polyolefin resin of the A layer or the C layer is polypropylene, an ethylene-propylene copolymer, or a mixed resin thereof.   Content of the fine powder filler of A layer is 20-70 mass% with respect to the mass of the whole A layer, The reflective film in any one of Claims 1-4 characterized by the above-mentioned.   Content of the fine powder filler of C layer is 10-80 mass% with respect to the mass of the whole C layer, The reflective film in any one of Claims 1-5 characterized by the above-mentioned.   The reflective film according to claim 1, wherein the fine powder filler is titanium oxide.   The reflective film according to claim 1, wherein the fine powder filler is titanium oxide having a vanadium content of 5 ppm or less.   The reflective film according to claim 1, wherein an A layer is disposed on the reflective use surface side.   10. The reflective film according to claim 1, wherein the stretched polyester film constituting the layer B is a biaxially stretched polyethylene terephthalate film obtained by biaxially stretching a film containing polyethylene terephthalate.   The reflective film according to claim 1, wherein the B layer contains a fine powder filler, a resin incompatible with the polyester resin, or both.   B layer has a space | gap, The reflective film in any one of Claims 1-11 characterized by the above-mentioned.   The reflective film according to claim 1, wherein the reflectance of the film surface on the reflective use surface side with respect to light having a wavelength of 550 nm is 95% or more.   A reflecting plate comprising the reflecting film according to claim 1.