JP2008233339A - Reflection film and reflection plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel reflection film improving light reflectivity and dimensional stability under a heated condition. <P>SOLUTION: The reflection film is provided with a layer A containing an aliphatic polyester based resin and a powdery filler, a layer B containing a polyolefin based resin and a powdery filler and a layer C composed of a biaxially oriented polyester film. Light reflectivity can be obtained from refractive scattering due to difference between refractive indices of the aliphatic polyester based resin and the powdery filler in the layer A and light transmitted through the layer A can be reflected again in the layer B. Thereby, higher reflectivity can be obtained. The layer C can reduce dimensional change of the film at 80°C and dimensional stability under the heated condition is increased. <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.

  The present invention comprises a reflection layer comprising an A layer containing an aliphatic polyester resin and a fine powder filler, a B layer containing a polyolefin resin and a fine powder filler, and a C layer comprising a biaxially stretched polyester film. Propose a 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 light reflectivity (also referred to as “reflectivity”) from the refractive scattering due to the refractive index difference between the aliphatic polyester resin and the fine powder filler in the A layer, and the B layer. Also in the case, the reflectivity can be obtained from the refractive scattering due to the difference in refractive index between the polyolefin resin and the fine powder filler. Therefore, for example, since the light transmitted through the A layer can be reflected again by the B layer, even higher reflectivity can be obtained.
In addition, since the C layer is a layer composed of a biaxially stretched polyester film, the dimensional change of the film at 80 ° C., which is a standard for heat resistance evaluation, can be reduced, and the dimensional stability under a heating environment can be reduced. It is excellent.

  Furthermore, in the reflective film of the present invention, since the B layer contains a polyolefin resin, if the B layer is present in the surface layer, it may turn yellow due to ultraviolet deterioration or oxidation deterioration, but the surface side (irradiated with light). If layer A is laminated in the order of layer A / layer B / layer C, the layer A functions as a barrier layer for layer B, thus preventing yellowing by suppressing ultraviolet and oxidative degradation of layer B. can do.

  As described above, the reflective film and the reflective plate of the present invention can realize excellent reflectivity, are excellent in dimensional stability under a heating environment, and can prevent yellowing due to ultraviolet deterioration or the like. Suitable as a reflective film used for reflectors such as displays for personal computers and televisions, lighting fixtures, lighting signs, etc., and particularly suitable as a reflective film for applications requiring excellent heat resistance, such as large liquid crystal televisions. It is.

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 includes an A layer that plays a role of imparting light reflectivity to the reflective film, and a B layer that plays a role of mainly imparting light reflectivity to the reflective film. And a C layer that mainly serves to impart heat-resistant dimensional stability to the reflective film.

[A layer]
A layer is a layer which consists of the resin composition A which contains an aliphatic polyester-type resin and a fine powder filler as a main component.

(Aliphatic polyester resin)
As the aliphatic polyester-based resin as the base resin of the A layer (resin forming the main component of the A layer), those chemically synthesized, those fermented and synthesized by microorganisms, and mixtures thereof can be used.
Chemically synthesized aliphatic polyester resins include aliphatic polyester resins obtained by ring-opening polymerization of lactones such as poly-ε-caprolactam, polyethylene adipate, polyethylene azelate, polyethylene succinate, polybutylene adipate, and polybutylene. Aliphatic polyester resins obtained by polymerizing dibasic acids and diols, such as azelate, polybutylene succinate, polybutylene succinate adipate, polytetramethylene succinate, cyclohexanedicarboxylic acid / cyclohexanedimethanol condensate , Aliphatic polyester resins obtained by polymerizing hydroxycarboxylic acids such as polylactic acid and polyglycol, a part of ester bonds of the aliphatic polyester resins, for example, 50% or less of all ester bonds are amide bonds, Ether bond include aliphatic polyester resins that are replaced by a urethane bond.
Examples of the aliphatic polyester resin fermented and synthesized by microorganisms include polyhydroxybutyrate, a copolymer of hydroxybutyrate and hydroxyvalerate, and the like.

  The aliphatic polyester resin used for the A layer is preferably an aliphatic polyester resin not containing an aromatic ring. If it is an aliphatic polyester-based resin that does not contain an aromatic ring in the molecular chain, it does not absorb ultraviolet rays, so it is exposed to ultraviolet rays or by receiving ultraviolet rays emitted from a light source such as a liquid crystal display device. Is not deteriorated or yellowed, and the light reflectivity of the film can be prevented from decreasing over time.

  The melting point of the aliphatic polyester resin used for the A layer is preferably 100 to 170 ° C. If melting | fusing point is 100-170 degreeC, it can suppress that a reflectance falls in a high temperature environment, or a dimensional stability falls.

In the A layer, light reflectivity can be obtained by refractive scattering at the interface between the base resin and the fine powder filler. Since this refractive scattering increases as the difference in refractive index between the base resin and the fine powder filler increases, the base resin has a low refractive index so that the refractive index difference from the fine powder filler increases. It is preferable to use a resin. From this point of view, it is preferable to use an aliphatic polyester resin having a refractive index of less than 1.52, rather than an aromatic polyester resin having a refractive index of about 1.55 or more. It is more preferable to use a lactic acid polymer having a low rate (refractive index of less than 1.46).
In addition, since the lactic acid polymer does not contain an aromatic ring in the molecular chain, it does not absorb ultraviolet rays. Therefore, the reflective film is not deteriorated or yellowed by being exposed to ultraviolet rays or by ultraviolet rays emitted from a light source such as a liquid crystal display device.

  A lactic acid-type polymer means the homopolymer of D-lactic acid or L-lactic acid, or those copolymers. Specifically, poly (D-lactic acid) whose structural unit is D-lactic acid, poly (L-lactic acid) whose structural unit is L-lactic acid, and a copolymer of L-lactic acid and D-lactic acid. There are poly (DL-lactic acid) and mixtures thereof are also included.

The lactic acid polymer can be produced by a known method such as a condensation polymerization method or a ring-opening polymerization method. For example, in the condensation polymerization method, D-lactic acid, L-lactic acid, or a mixture thereof can be directly subjected to dehydration condensation polymerization to obtain a lactic acid polymer having an arbitrary composition. Further, in the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, is subjected to ring-opening polymerization in the presence of a predetermined catalyst while using a polymerization regulator or the like as necessary, and lactic acid having an arbitrary composition. A polymer can be obtained.
The lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and DL-lactide, which is a dimer of D-lactic acid and L-lactic acid, By mixing and polymerizing these as necessary, a lactic acid polymer having an arbitrary composition and crystallinity can be obtained.

The content ratio of D-lactic acid and L-lactic acid in the lactic acid-based polymer used for the A layer is such that D-lactic acid: L-lactic acid = 100: 0 to 85:15 or D-lactic acid: L-lactic acid = 0. : 100 to 15:85 are preferable, and in particular, D-lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5, or D-lactic acid: L-lactic acid = 0.5: 99. It is preferable that the ratio is 5 to 5:95.
A lactic acid polymer having a content ratio of D-lactic acid and L-lactic acid of 100: 0 or 0: 100 exhibits very high crystallinity, has a high melting point, and tends to have excellent heat resistance and mechanical properties. That is, when the film is stretched or heat-treated, the resin is crystallized to improve heat resistance and mechanical properties, which is preferable in that respect. On the other hand, a lactic acid-based polymer composed of D-lactic acid and L-lactic acid is preferable in that respect because flexibility is imparted and film forming stability and stretching stability are improved.
Considering the balance between the heat resistance, molding stability and stretching stability of the resulting reflective film, the composition ratio of D-lactic acid and L-lactic acid is D-lactic acid: L-lactic acid = 99.5: 0.5. It is more preferable that it is -95: 5 or D-lactic acid: L-lactic acid = 0.5: 99.5-5: 95.

A plurality of types of lactic acid polymers having different content ratios of D-lactic acid and L-lactic acid may be mixed (blended). For example, by blending a homopolymer of D-lactic acid or L-lactic acid and a copolymer thereof, it is possible to balance the difficulty of bleeding and the development of heat resistance.
When a plurality of types of lactic acid polymers are mixed in this manner, the average value of the content ratios of D-lactic acid and L-lactic acid in the plurality of lactic acid polymers may be within the above range. .

  The molecular weight of the lactic acid polymer is preferably a high molecular weight. For example, the weight average molecular weight is preferably 50,000 or more, more preferably 60,000 to 400,000, and particularly preferably 100,000 to 300,000. When the weight average molecular weight of the lactic acid polymer is less than 50,000, the obtained film may be inferior in mechanical properties.

  A commercial product can be used for the aliphatic polyester resin used for the A layer. For example, the Bionore 3000 series from Showa Polymer Co., Ltd. and GS-Pla from Mitsubishi Chemical Corporation can be used. Examples of the lactic acid-based polymer include the Lacia series from Mitsui Chemicals, the NatureWorks series from NatureWorks, and the like.

(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 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 10 to 60% by mass with respect to the mass of the entire A layer in consideration of the light reflectivity, mechanical properties, productivity, etc. of the film, and 20 to 50% by mass. More preferably. 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 high light reflectivity can be imparted to the film. it can. Moreover, if content of a fine powder filler is 60 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 aliphatic polyester resin as described above within a range not impairing the effects of the aliphatic polyester resin and the fine powder filler. Further, within the range that does not impair the effects of the aliphatic polyester resin and the fine powder filler, hydrolysis inhibitor, antioxidant, light stabilizer, heat stabilizer, lubricant, dispersant, ultraviolet absorber, white pigment, You may contain a fluorescent whitening agent and another additive.

  As a resin other than the aliphatic polyester-based resin, for example, when a lactic acid-based polymer is used as a base resin, carbodiimide, which is a hydrolysis inhibitor, for the purpose of imparting durability to a higher temperature and higher humidity environment. It is conceivable to add a compound or the like.

Preferred examples of the carbodiimide compound include those having a basic structure represented by the following general formula (1).
(1) ...- (N = C = N-R-) n-
In the formula, n represents an integer of 1 or more, and R represents an organic bond unit. For example, R can be either aliphatic, alicyclic, or aromatic. In addition, n is generally an appropriate integer selected from 1 to 50.

Specifically, for example, bis (dipropylphenyl) carbodiimide, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (tolylcarbodiimide), poly ( Examples of the carbodiimide compound include diisopropylphenylenecarbodiimide), poly (methyl-diisopropylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide), and the like. These carbodiimide compounds may be used alone or in combination of two or more.
The addition amount of the carbodiimide compound is preferably 0.5 to 10.0 parts by mass with respect to 100 parts by mass of the aliphatic polyester resin. If the addition amount of the carbodiimide compound is 0.5 parts by mass or more, the hydrolysis resistance improving effect can be sufficiently exhibited. Moreover, if the addition amount of a carbodiimide compound is 10.0 mass parts or less, there will be little coloring of the film obtained and light reflectivity will not be impaired.

(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.

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

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 5% or more, particularly 5 to 50%, and more preferably 5 to 35%.
If the porosity is 5% or more, the reflectance can be improved. On the other hand, 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, when considering the point of improving the reflectance, the porosity is more preferably 20% or more, and further preferably 30% 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

[B layer]
B layer is a layer which consists of the resin composition B which contains 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 for the B layer (resin that forms the main component of the B layer) include monoolefin polymers such as polyethylene and polypropylene, and copolymers thereof. Specific examples include low density polyethylene, linear low density polyethylene (ethylene-α-olefin copolymer), medium density polyethylene, polyethylene resin such as high density polyethylene, polybutylene resin, polypropylene, ethylene-propylene copolymer, etc. And polypropylene resin, 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 multi-site 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 may be used as the polyolefin-based resin as the base resin for the B 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)
The fine powder filler used in the B layer can be the same as the fine powder filler used in the A layer, and the preferred type is also the same as that of the A layer.

  The content of the fine powder filler is preferably 20 to 70%, particularly 30 to 60% with respect to the mass of the entire B layer in view of the light reflectivity, mechanical properties, productivity and the like of the film.

(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.
Each specific example is similar to the A layer.

(Form)
The layer B 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). Moreover, when forming and laminating | stacking a film, the film may be an unstretched film, and may be a uniaxial or biaxially stretched film.

(Porosity)
The B layer can also have voids inside. If it has voids, in addition to refractive scattering due to the refractive index difference between the base resin and fine powder filler, refraction due to the refractive index difference between the base resin and void (air), and between the fine powder filler and void (air). Reflectivity can also be obtained from scattering.
For example, voids can be formed in the B layer by stretching a film containing a fine powder filler. Further, voids can also be formed in the B layer by adding a foaming agent and causing foaming.
The porosity of the B layer, that is, the ratio of the volume portion of the voids in the B layer is preferably 3% or more, particularly 3 to 35%, and particularly preferably 5 to 35%.
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.

[C layer]
The C layer is a layer composed of a biaxially stretched polyester film formed by biaxially stretching a film obtained by forming a film from a resin containing a polyester-based resin as a base resin (resin which is the main component of the C layer). It is.

(Base resin)
Examples of the polyester resin as the base resin for the C 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 -A copolymer obtained by copolymerization with one or more dicarboxylic acid components selected from naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid and the like.

(Other ingredients)
The C layer may contain a fine powder filler, a resin that is incompatible with the polyester resin (referred to as “incompatible resin”), or both.
By containing the fine powder filler or incompatible resin, voids are formed in the C layer when biaxially stretched. Therefore, the fine powder filler or 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 fine powder filler or incompatible resin in the C layer (the total content when both are included) 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 C layer contains a fine powder filler or an incompatible resin, the C layer is formed from a stretched film, so that voids are formed in the C layer as described above.
Under the present circumstances, it is preferable that the porosity of C layer, ie, the ratio of the volume part of the space | gap which occupies in C 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.

It is also possible to add a foaming agent to the C layer and form voids in the C layer by this foaming.
Examples of the method for forming voids in the C layer by foaming include a method in which an organic or inorganic thermally 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, a B layer, and a C layer. For example, the A layer / B layer / C layer, A layer / 3 layers that are laminated in the order of C layer / B layer, B layer / A layer / C layer, B layer / C layer / A layer, C layer / A layer / B layer, or C layer / B layer / A layer Even if it consists of a 4 layer structure laminated | stacked in order of a structure, A layer / B layer / A layer / C layer, or B layer / A layer / B layer / C layer, etc., or more. Good.

  Among them, a laminated structure including a three-layer structure in which layers A / B / C, B / A / C, etc. are laminated in this order from the surface side (the side irradiated with light), in particular, the surface A laminated structure including a three-layer structure in which layers A, B, and C are laminated in this order from the side (the side irradiated with light) is preferable. When the layer is arranged in the order of layer A / layer B from the light irradiation side (reflection use surface side) and the layer C is disposed behind it, the light transmitted through the layer A can be reflected again by the layer B. In addition to being able to obtain even higher reflectivity, the heat resistance of the C layer can be directly enjoyed, and further, the A layer functions as a barrier layer for the B layer against ultraviolet rays and oxidation transmission. , UV degradation and oxidation degradation of the B layer can be suppressed, and yellowing of the reflective film can be prevented. 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.

  In addition to the A layer, the B layer, and the C layer, other layers may be provided, and other layers may be interposed between the A layer, the B layer, and the C layer. For example, an adhesive layer may be interposed between the A layer, the B layer, the B layer, and the C layer.

(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 and the B layer is 20 to 90%, preferably 40 to 80%, more preferably 50 to 70% in terms of the thickness ratio with respect to the total thickness of the reflective film. It is. If it is 20% or more, light reflectivity can be sufficiently imparted, and if it is 90% or less, heat resistance can be imparted.

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 400 μm, particularly 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 C constituting the C layer are prepared or prepared, and the B layer and the adhesive layer are formed by, for example, adhesive layer / B layer. Co-extruded to form an adhesive layer, and the film A and the film C are laminated through the adhesive layer, respectively, so that a layered structure of A layer / adhesive layer / B layer / adhesive layer / C layer The reflective film which consists of can be manufactured. (2) A film B constituting the B layer is formed, and the film A, the film B, and the film C are laminated via an adhesive, respectively, so that A layer / adhesive layer / B layer / adhesive layer A reflective film having a laminated structure of / C layers can also be produced. Further, (3) a reflective film having a laminated structure of A layer / B layer / C layer can be produced by co-extrusion so as to be A layer / B layer / C layer.
Such a production method of (1) to (3) is an example of a production method of a reflective film having a laminated structure of A layer / adhesive layer / B layer / adhesive layer / C layer or A layer / B layer / C layer. However, it is not limited to such a manufacturing method. For example, the A layer may be formed into a thin film by co-extruding a molten resin composition together with a resin of another layer or by applying it on another layer. Moreover, if it is a reflection film which consists of another laminated structure, another preferable manufacturing method can also be illustrated.
However, here, the production method (1) will be described in detail as an example of a preferred production method of the reflective film.

(Preparation of film A for A layer formation)
The film A constituting the A layer is prepared by blending an aliphatic polyester resin and a fine powder filler, preparing a resin composition A, melting the resin composition A to form a film, and stretching as necessary. Thus, the film A may be produced.
Hereinafter, the production method of the film A will be described in detail.

First, a resin composition A is prepared by blending an aliphatic polyester resin with a fine powder filler and, if necessary, other additives such as a hydrolysis inhibitor.
Specifically, after adding fine powder filler, hydrolysis inhibitor, etc. to aliphatic polyester resin and mixing with ribbon blender, tumbler, Henschel mixer, etc., Banbury mixer, single screw or twin screw extruder etc. are used. Then, the resin composition A is obtained by kneading at a temperature equal to or higher than the melting point of the base resin (for example, 170 ° C. to 230 ° C. in the case of a lactic acid polymer).

  In addition, the resin composition A can also be obtained by adding a predetermined amount of an aliphatic polyester-based resin, a fine powder filler, a hydrolysis inhibitor, and the like with separate feeders. In addition, a so-called master batch in which a fine powder filler, a hydrolysis inhibitor and the like are blended in high concentration in an aliphatic polyester resin is prepared in advance, and the master batch and the aliphatic polyester resin are mixed to obtain a desired one. It can also be set as the resin composition A having a concentration.

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. For example, the extrusion temperature is preferably set within a range of 170 ° C. to 230 ° C. when a lactic acid polymer is used as the aliphatic polyester resin.

  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, for example, 50 to 90 ° C. in the case of a lactic acid-based polymer. It is preferable to do this. 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 5 times or more, and more preferably 7 times or more.
If the cast sheet is stretched so that the area magnification is 5 times or more, a porosity of 5% or more can be realized inside the film, and a porosity of 20% or more is realized by stretching 7 times or more. It is possible to achieve a porosity of 30% or more by stretching 7.5 times or more.

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 C for forming C layer)
The film C constituting the C layer is prepared by blending a polyester resin with additives such as a fine powder filler as necessary to prepare a resin composition C, and melting the resin composition C into a film shape. After film formation, the film C may be produced by biaxial stretching.
Hereinafter, the production method of the film C will be described in detail.

  First, blend a polyester resin with fine powder filler or other additives as necessary, mix with a ribbon blender, tumbler, Henschel mixer, etc., then use a Banbury mixer, single screw or twin screw extruder, etc. Then, the resin composition C is obtained by kneading at a temperature 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 C by adding a predetermined amount with a polyester-type resin, a fine powder filler, an additive, etc. with a separate feeder. In addition, a so-called master batch in which a fine powder filler or additive is blended in a polyester resin at a high concentration is prepared in advance, and this master batch and the polyester resin are mixed to obtain a resin composition C having a desired concentration. It is good.

Next, the resin composition C is dried, supplied to an extruder, and heated to a temperature equal to or higher than the melting point of the resin and melted.
At this time, the resin composition C 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 C 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.

Next, the obtained cast sheet can be biaxially stretched to obtain a film C.
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 C 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.

(Preparation of resin composition B for forming B layer)
First, a resin composition B is prepared by blending a polyolefin resin with a fine powder filler and, if necessary, other additives such as a hydrolysis inhibitor.
Specifically, after adding a fine powder filler, hydrolysis inhibitor, etc. to the polyolefin resin, mixing with a ribbon blender, tumbler, Henschel mixer, etc., using a Banbury mixer, a single or twin screw extruder, Resin composition B is obtained by kneading at a temperature equal to or higher than the melting point of the base resin.

The resin composition B can also be obtained by adding a predetermined amount of a polyolefin-based resin, a fine powder filler, a hydrolysis inhibitor, and the like with separate feeders.
In addition, a so-called master batch in which a fine powder filler, a hydrolysis inhibitor, etc. are blended in a high concentration in a polyolefin resin in advance is prepared, and this master batch and the polyolefin resin are mixed to obtain a resin composition having a desired concentration. It can also be the thing B.

(Lamination of A layer / B layer / C layer)
As a method of laminating the A layer / B layer / C layer, for example, the resin composition B is put into a melt kneading extruder and melted, while the adhesive layer resin is put into another melt kneading extruder and melted. The molten resin composition is extruded from the slit-shaped discharge port of the T-die, and is solidified by a cooling roll to form a laminated sheet of two types and three layers of adhesive layer / B layer / adhesive layer, and at the same time The film A and the film C are bonded to the adhesive layer and laminated, whereby a reflective film having a laminated structure of A layer / adhesive layer / B layer / adhesive layer / C layer can be produced.

[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.

(1) 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. Prior to the measurement, the photometer was set so that the reflectance of the alumina white plate was 100%.

(2) Thermal contraction rate (%)
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 film. The cut sample film was placed in a hot air circulating oven at a temperature of 80 ° C. and held for 180 minutes, and then the amount of contraction of the sample film was measured.
The ratio of the shrinkage amount to the original size (200 mm) of the sample film before being put in the oven was displayed as a% value, and this was defined as the thermal shrinkage rate.

(3) 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 was 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: Unevenness with a height of less than 1 mm was observed on the heated film.
D: Unevenness with a height of 1 mm or more was observed in the heated film.

(4) Weather resistance evaluation The reflective film was irradiated with ultraviolet rays for 1,000 hours in a sunshine weather meter tester. Thereafter, the surface of the film was observed with the naked eye, and by visual judgment, the white color of the film surface was indicated as “white”, and the yellowish color was indicated as “yellow”.

[Example 1]
In this example, a reflective film having a laminated structure of A layer / adhesive layer / B layer / adhesive layer / C layer was produced.

(Film A for A layer formation)
Pellets of a lactic acid polymer having a weight average molecular weight of 180,000 (NW3001D: manufactured by NatureWorks, L-form content: 98.5%, D-form content: 1.5%), and rutile-type oxidation having an average particle size of 0.25 μm Titanium (coated with alumina and silica, vanadium content 0.5 ppm) was mixed at a mass ratio of 70:30 to form a mixture. Resin composition A was prepared by adding 0.5 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture. Thereafter, the resin composition A is sufficiently dried, then supplied to a twin screw extruder heated to 205 ° C., kneaded at 205 ° C. using this twin screw extruder, and then melted resin composition A was extruded into a sheet form from a T-die and cooled and solidified to obtain a film.
The obtained film was roll-stretched 2.5 times to MD at a temperature of 65 ° C., then biaxially stretched by tenter stretching to TD at a temperature of 70 ° C., and then heat-treated at 140 ° C. A film A (a porosity of 24%) for forming an A layer having a thickness of 75 μm was obtained.

(Film C for forming C layer)
As the film C for forming the C layer, a biaxially stretched polyester film (Diafoil S100-100: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) having a thickness of 100 μm was prepared.

(Resin composition B for forming layer B)
As a resin composition for forming the B layer, 60 parts by mass of polypropylene resin (Novatech PP FY4: manufactured by Nippon Polypro Co., Ltd.) and rutile titanium oxide having an average particle size of 0.25 μm (covered with alumina and silica, containing vanadium) Resin composition B was prepared by mixing 40 parts by mass of 0.5 ppm).

(Adhesive resin D for forming the adhesive layer)
As the resin composition D for forming the adhesive layer, a styrene-based thermoplastic elastomer (Dynalon 8630: manufactured by JSR) was prepared.

(Lamination of A layer / B layer / C layer)
The resin composition B and the adhesive resin D are 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 laminated at a casting temperature of 90 ° C. (adhesion) Layer / B layer / adhesive layer) and laminated on this laminated sheet while nip-rolling the film A for forming the A layer from the cast surface side and the film C for forming the C layer from the non-cast surface side, A reflective film (A layer / adhesive layer / B layer / adhesive layer / C layer) having a thickness of 400 μm was obtained.
About the obtained reflective film, the said measurement and evaluation were performed and the result was shown in Table 1.

[Comparative Example 1]
The film A for forming the A layer formed in Example 1 was subjected to measurements and evaluations such as reflectance, shrinkage, and heat resistance evaluation, and the results are shown in Table 1.

[Comparative Example 2]
As a resin composition for the B layer, 60 parts by mass of polypropylene resin (Novatech PP FY4: manufactured by Nippon Polypro Co., Ltd.) and rutile titanium oxide having an average particle size of 0.25 μm (covered with alumina and silica, vanadium content is 0) 0.5 ppm) using a resin composition mixed with 40 parts by mass, this was melt-kneaded at a set temperature of 200 ° C. using a twin screw extruder, merged with a T-die, and extruded at a cast temperature of 90 ° C. A 200 μm film (B layer) was obtained.
The obtained film was measured and evaluated, and the results are shown in Table 1.

Claims (8)

  A reflective film comprising an A layer containing an aliphatic polyester resin and a fine powder filler, a B layer containing a polyolefin resin and a fine powder filler, and a C layer made of a biaxially stretched polyester film.   Content of the fine powder filler of A layer is 10-60 mass% with respect to the mass of the whole A layer, The reflective film of Claim 1 characterized by the above-mentioned.   The reflective film according to claim 1 or 2, wherein the porosity of the A layer is 5% or more.   Content of the fine powder filler of B layer is 20-70 mass% with respect to the mass of the whole B layer, The reflective film in any one of Claims 1-3 characterized by the above-mentioned.   The reflective film according to any one of claims 1 to 4, wherein the aliphatic polyester resin of the A layer is a lactic acid polymer.   The reflective film according to any one of claims 1 to 5, wherein the fine powder filler in either or both of the A layer and the B layer is titanium oxide.   The biaxially stretched polyester film constituting the C layer is a biaxially stretched polyethylene terephthalate film obtained by biaxially stretching a film containing polyethylene terephthalate. The reflection according to any one of claims 1 to 6, the film.   A reflecting plate comprising the reflecting film according to claim 1.