JP2008225323A - Reflective film and reflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection film having small size change even if being preserved under a high temperature environment and achieving high reflection performance. <P>SOLUTION: The reflection film has a laminate having an A layer mainly comprising a resin composition A containing an aliphatic polyester-based resin and a fine particulate filler, and a B layer consisting of a woven material or a non-woven material. The material of the woven material or the non-woven material is preferable in a polyester-based or glass-based material independently respectively. In addition, the aliphatic polyester-based resin is preferable in a lactic acid-based polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reflection film and a reflection plate, and more particularly to a reflection film used for a reflection plate such as a liquid crystal display, a lighting fixture, and a lighting signboard, and a reflection plate provided with the reflection film.

  In recent years, reflective films have been used in fields such as reflectors for liquid crystal display devices, projection screens and planar light source members, reflectors for lighting fixtures, reflectors for lighting signs, and the like. For example, reflecting plates for liquid crystal displays, in order to improve the performance of the backlight unit by supplying as much light as possible to the liquid crystal due to the demand for larger screens and advanced display performance, the reflective performance of the reflective unit is high. There is a need for films.

  In addition, when a reflective film is incorporated as a reflective plate for a large liquid crystal television or the like, the reflective film is used in a state of being exposed to a light source for a long time. There is a need for a reflective film having heat resistance that does not generate creases and wrinkles, and particularly excellent in heat resistance having dimensional stability even after being stored in a high temperature environment.

  For example, Japanese Patent Application Laid-Open No. 2004-151707 discloses a light reflector that is a laminate of a polyolefin resin film in which voids are formed by containing a filler and a nonwoven fabric, but the interface between the film and the nonwoven fabric is disclosed. The strength was insufficient and the dimensional stability was not sufficient.

In addition, the present inventors have proposed a reflection film obtained by adding a fine powder filler such as titanium oxide to an aliphatic polyester resin as a reflection film capable of realizing excellent reflection performance (for example, Patent Documents). 2).

  However, in recent years, the demand for higher brightness of products has led to a demand for a reflective film having even higher reflective performance, and there is also a need for a reflective film having excellent dimensional stability. A reflective film that satisfies these requirements does not yet exist.

JP 2004-151707 A International Publication WO2004 / 104077

  The present invention has been made to solve the above-mentioned problems, and the present invention provides a reflective film that can realize high reflection performance and has little dimensional change even when stored in a high temperature environment. With the goal.

  The reflective film of the present invention is a laminate having an A layer mainly composed of a resin composition A containing an aliphatic polyester resin and a fine powder filler, and a B layer made of a woven material or a non-woven material. It is characterized by that.

  Here, the material of the woven material and the non-woven material can be independently a polyester-based material or a glass-based material.

  In the present invention, it is preferable that at the interface between the A layer and the B layer, the B layer and the A layer are fitted and a resin for forming the A layer is mixed in the B layer.

  Moreover, it is preferable that the peeling strength at the time of peeling the said A layer and the said B layer at these interfaces is 95 g / cm or more.

  In the present invention, the laminate is preferably formed by an extrusion laminating method.

  The aliphatic polyester resin is preferably a lactic acid polymer.

  In this invention, it is preferable that the reflectance in the wavelength range of 550 nm of a reflective film is 95% or more.

  The reflecting plate of the present invention comprises any one of the above reflecting films.

  According to the present invention, a reflective film having high light reflectivity and little dimensional change even in a high temperature environment can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.
The reflective film of the present invention is a laminate having an A layer mainly composed of a resin composition A containing an aliphatic polyester resin and a fine powder filler, and a B layer made of a woven material or a non-woven material. . This A layer is a layer which can mainly provide light reflectivity to a reflective film, and this B layer is a layer which can mainly provide heat resistance and dimensional stability to a reflective film.

Here, the “main component” means to allow other components to be contained within a range that does not interfere with the function of the resin composition A serving as the main component, and in particular, the resin composition serving as the main component. Although the content ratio of A is not specified, for example, the content ratio of the resin composition A is 50% by mass or more, preferably 70% by mass or more, particularly preferably in the resin composition forming the A layer. Is 90% by mass or more (including 100% by mass). However, when the resin composition A as the main component is composed of two or more components, the total amount thereof is within the above range.
In the present invention, when “main component” is displayed in addition to the above, it has the same meaning as described above unless otherwise specified.

  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), and “sheet” generally refers to a product that is thin according to the definition in JIS, and whose thickness is usually small and flat instead of length and width. However, the boundary between the sheet and the film is not clear, and in the present invention, it is not necessary to distinguish both in terms of the wording. Therefore, in the present invention, even when the term “film” is used, the term “sheet” is included. "Film" is also included.

  Further, in this specification, when expressed as “X to Y” (X and Y are arbitrary numbers), “X or more and Y or less” is intended unless otherwise specified. The intention of “preferably smaller” is also included.

  The A layer constituting the reflective film of the present invention is a film-like or thin-film layer, and uses a resin composition mainly composed of a resin composition A containing an aliphatic polyester-based resin and a fine powder filler. Become.

(Aliphatic polyester resin)
As the aliphatic polyester resin, those chemically synthesized, those fermented and synthesized by microorganisms, and mixtures thereof can be used.

  Examples of chemically synthesized aliphatic polyester resins include poly (epsilon) -caprolactone obtained by ring-opening polymerization of lactone, polyethylene adipate obtained by polymerizing dibasic acid and diol, polyethylene azelate, polybutylene succinate And polybutylene succinate / adipate, polytetramethylene succinate, cyclohexanedicarboxylic acid / cyclohexanedimethanol condensate, and the like, polylactic acid obtained by polymerizing hydroxycarboxylic acid, polyglycol and the like. In addition, an aliphatic polyester in which a part of the ester bond of the above-described aliphatic polyester, for example, 50% or less is replaced with an amide bond, an ether bond, a urethane bond, or the like can be used. These can be used alone or in admixture of two or more.

  Examples of aliphatic polyester resins 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 resin that does not contain an aromatic ring in the molecular chain. An aliphatic polyester resin that does not contain an aromatic ring in the molecular chain does not absorb ultraviolet rays, so the film deteriorates when exposed to ultraviolet rays or by ultraviolet rays emitted from a light source such as a liquid crystal display device. Or yellowing. Therefore, it can suppress that the light reflectivity of a film falls with time.

  In order to obtain high light reflectivity by utilizing light refraction and scattering within the A layer, the aliphatic polyester resin is an aliphatic polyester resin that has a large difference in refractive index from the fine powder filler. Is preferably used. From such a viewpoint, as the base resin for the A layer, among the aliphatic polyesters, aliphatic polyester resins having a refractive index (n) of less than 1.52 are preferably used. If an aliphatic polyester-based resin having a refractive index (n) of less than 1.52 is contained as a base resin, a further excellent light reflectivity can be obtained by utilizing refractive scattering at the interface between the base resin and the fine powder filler. Obtainable. Since the refractive scattering effect increases as the refractive index of the base resin and the fine powder filler increases, the aliphatic polyester-based resin preferably has a smaller refractive index. A lactic acid polymer that is less than 1.46 (generally about 1.45) is the most preferred example.

  As the lactic acid-based polymer, a homopolymer of D-lactic acid or L-lactic acid or a copolymer thereof can be used. Specifically, poly (D-lactic acid) whose structural unit is D-lactic acid, poly (L-lactic acid) whose structural unit is L-lactic acid, and poly (L-lactic acid and D-lactic acid copolymer poly (L DL-lactic acid) and mixtures thereof.

  Whether the lactic acid polymer used in the reflective film of the present invention has a DL ratio, that is, a content ratio of D-lactic acid and L-lactic acid is D-lactic acid: L-lactic acid = 100: 0 to 85:15. Or D-lactic acid: L-lactic acid = 0: 100 to 15:85. By adjusting the content ratio of D-lactic acid and L-lactic acid to such a ratio, it is possible to balance the heat resistance, molding stability and stretching stability of the resulting reflective film. More preferably, D-lactic acid: L-lactic acid = 99.5: 0.5 to 95: 5, or D-lactic acid: L-lactic acid = 0.5: 99.5 to 5:95.

  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. In addition, 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 a lactic acid system 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.

In addition, you may blend the lactic acid-type polymer from which the copolymerization ratio of D-lactic acid and L-lactic acid differs.
In this case, it is preferable to adjust so that the average value of the copolymerization ratios of D-lactic acid and L-lactic acid of a plurality of lactic acid polymers falls within the range of the DL ratio.

  The lactic acid polymer preferably has a high molecular weight, for example, preferably has a weight average molecular weight of 10,000 or more, more preferably 60,000 or more, and still more preferably 400,000 or less. Among them, those having 100,000 or more are particularly preferable, or those having 300,000 or less are particularly preferable. When the weight average molecular weight of the lactic acid polymer is less than 10,000, the obtained film may have poor mechanical properties.

(Fine powder filler)
Examples of the fine powder filler used in the A layer include organic fine powder and inorganic fine powder. The organic fine powder is preferably at least one selected from the group consisting of cellulose powder such as wood powder and pulp powder, polymer beads, polymer hollow particles and the like. Inorganic fine powders are 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, It is preferably at least one selected from the group consisting of kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay and the like.

  From the viewpoint of further improving the light reflectivity of the reflective film, it is preferable to select a fine powder filler having a large refractive index difference from the aliphatic polyester resin. That is, it is preferable to select a fine powder filler having a higher refractive index, and it is preferable to use a fine powder filler having a refractive index of 1.6 or more as a standard. Specifically, it is preferable to use calcium carbonate, barium sulfate, titanium oxide or zinc oxide having a refractive index of 1.6 or more. Among them, titanium oxide, or fine powder filling other than titanium oxide and titanium oxide described above is used. It is preferable to use in combination with an agent. By using titanium oxide as a fine powder filler, it is possible to impart high reflective performance to the film with a smaller addition amount than when using a fine powder filler other than titanium oxide, and the film thickness is thin. High reflective performance can be imparted to the reflective film.

  The titanium oxide used in the reflective film of the present invention is preferably a titanium oxide having a crystal structure such as anatase-type titanium oxide or rutile-type titanium oxide. Among these, from the viewpoint of increasing the difference in refractive index from the base resin constituting the film, titanium oxide having a refractive index of 2.7 or more is preferable, and for example, rutile titanium oxide is preferably used. The greater the difference in refractive index, the greater the light refracting / scattering action at the interface between the base resin and titanium oxide, making it easier to impart light reflectivity to the film.

  In order to impart high light reflectivity to the film, it is preferable to use titanium oxide having a small light absorption ability for visible light. Therefore, it is particularly preferable to use high purity titanium oxide having high purity among titanium oxides. Here, high-purity titanium oxide refers to titanium oxide having a small light absorption capability for visible light, that is, titanium oxide having a low content of coloring elements such as vanadium, iron, niobium, copper, manganese, etc. High purity titanium oxide having a niobium content of 500 ppm or less is preferred. Such high-purity titanium oxide can be produced, for example, by a chlorine process. In the chlorine process, rutile ore mainly composed of titanium oxide is reacted with chlorine gas in a high-temperature furnace at about 1,000 ° C. to produce titanium tetrachloride. Subsequently, high purity titanium oxide can be obtained by burning this titanium tetrachloride with oxygen. In addition, although there is a sulfuric acid process as an industrial manufacturing method of titanium oxide, since titanium oxide obtained by this method contains a large amount of colored elements such as vanadium, iron, copper, manganese, niobium, etc., visible light Increases the light absorption capacity for. Therefore, it is difficult to obtain high-purity titanium oxide by the sulfuric acid method process.

  The surface of titanium oxide (including high-purity titanium oxide) used in the reflective film of the present invention is coated with at least one inert inorganic oxide selected from silica, alumina, and zirconia. Preferably it is. Thus, the titanium oxide coated with the inert inorganic oxide can improve the light resistance of the film without impairing the high light reflectivity of the titanium oxide, and can suppress the photocatalytic activity of the titanium oxide. Therefore, it is preferable. Further, titanium oxide coated with two or three kinds of inert inorganic oxides is more preferable. Among them, a combination of a plurality of inert inorganic oxides that require silica, that is, silica and other inert inorganic oxides. Titanium oxide coated with a combination of oxides (for example, alumina and zirconia) is particularly preferred. The surface treatment amount of the inert inorganic oxide to titanium oxide is preferably 0.5% by mass to 5% by mass in the total mass of the titanium oxide particles.

  As the fine powder filler, the inorganic fine powder and the organic fine powder exemplified above may be used in combination. Further, different types of fine powder fillers may be used in combination with inorganic fine powders, or different fine powder fillers may be used in combination with organic fine powders. For example, titanium oxide and other fine powder fillers, or high-purity titanium oxide and other fine powder fillers may be used in combination.

  Further, in order to improve the dispersibility of the fine powder filler in the resin, the fine powder filler whose surface is surface-treated with a silicon compound, a polyhydric alcohol compound, an amine compound, a fatty acid, a fatty acid ester, or the like. May be used. Examples of the surface treatment agent include at least one organic compound selected from the group consisting of at least one inorganic compound selected from the group consisting of alumina, silica, zirconia, and the like, a siloxane compound, a silane coupling agent, a polyol, and polyethylene glycol. A compound or the like can be used. Further, these inorganic compounds and organic compounds may be used in combination. The surface treatment amount of the surface treatment agent to titanium oxide is preferably 0.01% by mass to 5% by mass in the mass of the entire titanium oxide particles.

  The particle size of the fine powder filler is preferably 0.05 μm to 15 μm, more preferably 0.1 μm or more. The particle size of the fine powder filler is more preferably 10 μm or less. If the particle size of the fine powder filler is 0.05 μm or more, the dispersibility in the aliphatic polyester resin will not be lowered, so that a homogeneous film can be obtained. Further, when the particle diameter is 15 μm or less, when voids are formed, the voids do not become rough, and a film having a high reflectance can be obtained. Furthermore, when titanium oxide is used as the fine powder filler, the particle size is preferably 0.1 μm to 1 μm, more preferably 0.2 μm or more, or 0.5 μm or less. Is more preferable. If the particle size of titanium oxide is 0.1 μm or more, the dispersibility in the aliphatic polyester resin is good, and a homogeneous film can be obtained. Moreover, since the interface of aliphatic polyester-type resin and a titanium oxide will be formed densely if the particle size of a titanium oxide is 1 micrometer or less, high light reflectivity can be provided to a reflective film.

  The content of the fine powder filler contained in the A layer is preferably 10 to 60% by mass with respect to the mass of the entire A layer, considering the light reflectivity, mechanical properties, productivity, etc. of the film. The content is more preferably 20% by mass or more and 55% by mass or less, and particularly preferably 20% by mass or more and 50% by mass or less. If the content of the fine powder filler is 10% by mass or more, the area of the interface between the resin and the fine powder filler can be sufficiently secured, so that high light reflectivity can be imparted to the film. Moreover, if content of a fine powder filler is 60 mass% or less, the mechanical property required for a film can be ensured.

  By the way, in recent years, liquid crystal displays have been used not only for personal computer displays but also for car navigation systems for automobiles, compact TVs for vehicles, and the like, and those that can withstand high temperatures and high humidity have become necessary. Therefore, it is preferable to further use a hydrolysis inhibitor for the purpose of imparting durability to the aliphatic polyester resin reflective film.

Examples of the hydrolysis inhibitor preferably used in the present invention include carbodiimide compounds. Preferred examples of the carbodiimide compound include those having a basic structure represented by the following general formula.

-(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. When n is 2 or more, two or more R may be the same or different.

  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.

  In this invention, it is preferable to add 0.1-3.0 mass parts of carbodiimide compounds with respect to 100 mass parts of aliphatic polyester-type resin which comprises a film (A layer). If the addition amount of the carbodiimide compound is 0.1 parts by mass or more, the hydrolysis resistance improving effect is sufficiently exhibited in the obtained film or the like. Moreover, if the addition amount of a carbodiimide compound is 3.0 mass parts or less, the degree of coloring of the film obtained will be few and high light reflectivity will be obtained.

(Other ingredients)
A layer which comprises the reflective film of this invention may contain resin other than the above in the range which does not impair the effect of this invention. Further, within the range not impairing the effect of the present invention, hydrolysis inhibitor, antioxidant, light stabilizer, heat stabilizer, lubricant, dispersant, ultraviolet absorber, white pigment, fluorescent whitening agent, and other An additive may be contained.

<B layer>
The reflective film of the present invention has a B layer composed of a woven material and / or a non-woven material, thereby imparting strength to the reflective film, and the poor heat resistance that is a drawback of aliphatic polyester resins. In addition, it is possible to provide a reflective film that can suppress the occurrence of deflection during use and does not cause uneven brightness.

  As the woven material used in the present invention, nylon 6, nylon 66, polyethylene terephthalate, cotton, rayon, polyacrylonitrile, polyfluorinated ethylene, polypropylene, polyvinylidene fluoride and the like are used as materials, A metal mesh etc. are mentioned.

Moreover, as a nonwoven material used for this invention, the nonwoven material which consists of a polyester-type, nylon-type, and a glass-type material is mentioned. In these, the nonwoven material which consists of a polyester-type or glass-type material from a viewpoint of intensity | strength and reflective performance is preferable. The non-woven material is a sheet that is neither a knitted fabric nor a paper or a film, and refers to a sheet in which fibers are bonded by various bonding methods. Bonding methods include chemical bonds that are bonded with adhesives, self-adhesive or thermal bonds that are bonded with adhesive fibers, spunlaces that are entangled with high-pressure water currents, needle punches that are entangled with special needles, and threads that are not loosened. There are stitch bonds that are knitted in, spun bonds that are directly bonded by spinning, and bonded mainly by self-adhesion. Moreover, woven materials, weight per unit area of the nonwoven material is preferably ^{10g / cm 2 ~50g / cm 2} . When the weight per unit area of the woven material is within this range, a reflective film excellent in both strength and reflective performance can be obtained even under high temperature environmental conditions.

<Laminated body>
The reflective film of the present invention has a structure in which an A layer and a B layer are laminated. A reflection film in which an A layer having high reflection performance and a B layer having high heat resistance are laminated has characteristics of both, and is required for a reflection film constituting a reflection plate used for a large-sized liquid crystal television, for example. Heat resistance can be satisfied. Specifically, the dimensional stability under an 80 ° C. heating environment can be increased to a higher level.

  The laminated structure and the lamination ratio of the reflective film of the present invention are not particularly limited. However, when a preferred laminated structure is exemplified, the laminated film is laminated in order from the side irradiated with light (reflection use surface side). A layer / B layer two-type two-layer configuration or an A layer / B layer / A-layer two-type three-layer configuration is preferable. In the present invention, one or more layers (including different layers) other than the A layer and the B layer may be further included, and two or more A layers and / or two or more B layers may be included. Layers may be included.

  In the present invention, the A layer and the B layer are preferably fitted. Here, “fitting” means that, at the interface between the A layer and the B layer, the A layer is fitted in the B layer, and the resin forming the A layer is mixed in the B layer. The peel strength between the A layer and the B layer is preferably 95 g / cm or more, and more preferably 140 g / cm or more. Here, the peel strength refers to the T-type peel strength measured using a tensile tester under the conditions of a temperature of 23 ° C. and 50% RH under a tensile speed of 200 mm / min.

  As a method of laminating the A layer and the B layer, for example, a method in which an adhesive (including an adhesive sheet) is interposed between the film-like A layer and the B layer, and the film-like A layer and the B layer are bonded. In the present invention, the laminate is preferably laminated by the latter heat fusion method from the viewpoint of strength. Further, when the A layer and the B layer are laminated by the thermal fusion method, a laminate in which the A layer and the B layer are fitted is formed.

<Reflection film>
(Thickness)
The thickness of the reflective film of the present invention 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 view of handling in practical use.
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 be used for small and thin liquid crystal displays 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.

(Characteristic)
The reflective film of the present invention preferably has a surface reflectance of 95% or more, more preferably 97% or more, for light having a wavelength of about 550 nm. When the reflectivity is 95% or more, the reflection film exhibits good reflection characteristics and can give a sufficient brightness to a screen of a liquid crystal display or the like.

  In the reflective film of the present invention, the thermal shrinkage after heating at 80 ° C. for 180 minutes is greater than −0.1% and less than 0.7% in both the machine direction (MD) and the transverse direction (TD). preferable. In particular, it is more preferable that the thermal shrinkage rate is greater than 0%, or even less than 0.5%. For example, when a reflective film is incorporated in a reflector such as a large liquid crystal television, it will be used for a long time while being exposed to a light source. There is a need. That is, dimensional stability under a heating environment is required. For example, if the heat shrinkage ratio after heating the reflective film at 80 ° C. for 180 minutes is greater than −0.1% and less than 0.7% in both the machine direction (MD) and the transverse direction (TD), Flatness can be maintained.

<Manufacturing method>
Below, although an example is given and demonstrated about the manufacturing method of the reflective film of this invention, this invention is not limited to these manufacturing methods.

  First, an aliphatic polyester resin composition is prepared by blending an aliphatic polyester resin with a fine powder filler, if necessary, a hydrolysis inhibitor, and other additives. Specifically, titanium oxide is added to the aliphatic polyester-based resin, and further, an anti-hydrolysis agent or the like is added as necessary, and mixed with a ribbon blender, tumbler, Henschel mixer, etc. Alternatively, the resin composition can be obtained by kneading using a twin screw extruder or the like at a temperature equal to or higher than the melting point of the resin (for example, 170 ° C. to 230 ° C. in the case of a lactic acid polymer). Alternatively, a resin composition can be obtained by adding a predetermined amount of an aliphatic polyester resin, titanium oxide or the like with a separate feeder or the like. Alternatively, a so-called master batch in which titanium oxide or the like is blended with an aliphatic polyester resin at a high concentration in advance is prepared, and the master batch and the aliphatic polyester resin are mixed to obtain a resin composition having a desired concentration. You can also

  Next, the resin composition thus obtained is melted and formed into a film. For example, after drying the resin composition, it is supplied to an extruder and heated to a temperature equal to or higher than the melting point of the resin and melted. Or you may supply a resin composition to an extruder, without drying, but when not drying, it is preferable to use a vacuum vent at the time of melt-extrusion. Conditions such as the extrusion temperature need to be set in consideration of a decrease in molecular weight due to decomposition. For example, the extrusion temperature is in the range of 170 ° C. to 230 ° C. in the case of a lactic acid-based polymer. preferable. The molten resin composition is extruded from a slit-shaped discharge port of a T-die provided in an extruder, and is adhered and solidified to a cooling roll. At the same time, a reflective film is formed by laminating a woven material or a non-woven material as a B layer. Can be obtained.

<Application>
Since the reflective film of the present invention has high reflective performance and high heat resistance (dimensional stability), it is suitable as a reflective film used for a display plate of a personal computer, a TV, a lighting fixture, a lighting signboard, etc. In addition, it can also be suitably used for reflectors that require particularly excellent heat resistance, such as large liquid crystal televisions.

  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. It is. 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) Reflectance (%)
An integrating sphere is attached to a spectrophotometer ("U-4000", manufactured by Hitachi, Ltd.), and the wavelength is 550.
The reflectivity of the film for nm light was measured. In that case, light was irradiated from the reflective use surface side (side where light is irradiated) of the film, that is, the side where the A layer is disposed. However, the photometer was adjusted before the measurement so that the reflectance of the alumina white plate was 100%.

(2) Thermal contraction rate (%)
The reflective film was cut into an appropriate size, and a 200 mm wide marked line was put on each of MD and TD to prepare a sample for evaluation. The sample for evaluation 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 heat shrinkage (%).

(3) Heat resistance A reflective film was attached to a liquid crystal television by a method that is actually attached to a fixed frame of a reflective sheet incorporated in a backlight of a 32-inch liquid crystal television, and heated at 80 ° C. for 3 hours. Thereafter, the appearance of the film was observed with the naked eye and evaluated based on the following evaluation criteria.

Evaluation criteria:
A No change was observed in the appearance of the film after heating. B Although a change was visually observed in the film after heating, the height was less than 0.5 mm and was not measurable. C In the film after heating , Irregularities with a height of 0.5 mm or more and less than 1 mm were observed. D Unevenness with a height of 1 mm or more was observed on the heated film.

(4) Peel strength Peel strength was measured by peeling the interface between the A layer and B layer constituting the film. That is, using a tensile tester (manufactured by Intesco, Inc., 201X), the measurement was performed by a T-type peeling method in an environment of 23 ° C. and 50% RH under a tensile speed of 200 mm / min.

[Example 1]
(Preparation of titanium oxide A)
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 surface-treated with alumina and then surface-treated with trimethylolethane to produce titanium oxide A. However, the surface treatment amount (surface coating amount) with alumina was 3% by mass, and the surface treatment amount (surface coating amount) with trimethylolethane was 0.3% by mass.

(Preparation of resin composition)
Pellets of polylactic acid having a weight average molecular weight of 200,000 (NW4032D; manufactured by Nature Works, D-form content: 1.5%) and titanium oxide A were mixed at a ratio of 50% by mass to 50% by mass. Produced. To 100 parts by mass of this mixture, 2.5 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) was added and mixed, and then pelletized using a twin-screw extruder to produce a so-called master batch. Produced. This master batch and polylactic acid were mixed at a ratio of 60% by mass to 40% by mass to prepare a resin composition.

(Production of reflective film)
The obtained resin composition was supplied to an extruder heated to 200 ° C. Non-woven fabric (Ecule 3215A; Toyobo Co., Ltd.) made of a polyester material extruded from both sides of the cast roll side and the nip roll side by extruding the molten resin composition into a sheet using a T-die provided in the extruder A weight of 25 g / cm ² ) and a molten resin composition were laminated and cooled and solidified to form a film (B layer / A layer / B layer) of about 200 μm. Then, the obtained film was heat-treated at 110 ° C. for 10 minutes to produce a reflective film.
About the obtained reflective film, the reflectance, the heat shrinkage rate and the peel strength were measured, and the heat resistance was evaluated. The results are shown in Table 1.

[Example 2]
In the production of the reflective film in Example 1, a reflection having a thickness of about 200 μm was performed in the same manner as in Example 1 except that a glass-based nonwoven fabric (FBP025; manufactured by Olivest Co., Ltd., weight per unit area 25 g / cm ² ) was used as the nonwoven fabric. A film was prepared. About the obtained reflective film, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

[Comparative Example 1]
Mixing pellets of polylactic acid having a weight average molecular weight of 200,000 (NW4032D: manufactured by Nature Works, D-form content: 1.5%) and titanium oxide A in a ratio of 50% by mass to 50% by mass to produce a mixture did. To 100 parts by mass of this mixture, 2.5 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) was added and mixed, and then pelletized using a twin-screw extruder to produce a so-called master batch. Produced. This master batch and the polylactic acid were mixed at a ratio of 60% by mass: 40% by mass to prepare a resin composition.
This resin composition was supplied to an extruder heated to 200 ° C., and the molten resin composition was extruded into a sheet using a T-die and cooled and solidified to form a film. The obtained film was stretched 2.5 times to MD by roll stretching at a temperature of 65 ° C., biaxially stretched to 2.8 times to TD by temperature tenter stretching at a temperature of 65 ° C., and then heat-treated at 140 ° C. Thus, a reflective film having a thickness of 250 μm was obtained.
About the obtained reflective film, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

[Example 3]
A resin composition was prepared in the same manner as in Example 1. The obtained resin composition is supplied to an extruder heated to 200 ° C., and the molten resin composition is extruded into a sheet using a T-die provided in the extruder, and cooled and solidified to produce a sheet. did. Next, a non-woven fabric made of a polyester material (Ecule 3215A; manufactured by Toyobo Co., Ltd., basis weight 25 g / cm ² ) is bonded to the obtained sheet via an adhesive layer (styrene-based thermoplastic elastomer). A 200 μm film was prepared. Then, the obtained film was heat-treated at 110 ° C. for 10 minutes to produce a reflective film.
About the obtained film, the same measurement and evaluation as Example 1 were performed. The results are shown in Table 1.

From Table 1, the reflective films of Examples 1 to 3 showed excellent reflectivity even when they did not have voids therein, and the reflectivity of the film with respect to light having a wavelength of 550 nm was 95% or more. In addition, the reflective films of Examples 1 to 3 have a heat shrinkage ratio of greater than -0.1% and less than 0.7%, and are excellent in dimensional stability, and are practically usable in evaluation of heat resistance. It turns out that it satisfies. Among them, Examples 1 and 2 in which a layered body in which the A layer and the B layer are fitted to each other at the interface are higher in peel strength and superior in heat resistance than Example 3. It turned out to be a thing.
On the other hand, the comparative example 1 which does not have B layer was inferior in heat resistance, and was a reflection film especially unsuitable for a large sized liquid crystal television etc.

  According to the present invention, since a high reflection performance can be realized by refractive scattering due to the refractive index difference between the aliphatic polyester resin and the fine powder filler in the A layer, a reflective film having particularly excellent light reflectivity can be obtained. Obtainable. Moreover, the reflective film which laminated | stacked B layer which consists of a woven material and a non-woven material can compensate the lack of heat resistance of aliphatic polyester, and can suppress the wavy and bending of a reflective film in a heating environment. According to the present invention, it is possible to realize a reflective film that achieves high light reflectivity and has little dimensional change under a heating environment.

  The reflective film of the present invention is suitable as a reflective film for use in displays such as personal computers and televisions, lighting fixtures, reflectors for lighting signs, etc., and in particular, excellent heat resistance is required, such as large liquid crystal televisions. It is suitable as a reflective film for use.

Claims (8)

  A reflective film comprising a laminate having an A layer mainly composed of a resin composition A containing an aliphatic polyester resin and a fine powder filler, and a B layer made of a woven material or a non-woven material .   The reflective film according to claim 1, wherein the woven material and the non-woven material are each independently a polyester-based or glass-based material.   The B layer and the A layer are fitted at the interface between the A layer and the B layer, and a resin forming the A layer is mixed in the B layer. Reflective film.   The reflective film according to any one of claims 1 to 3, wherein a peel strength when the A layer and the B layer are peeled at the interface is 95 g / cm or more.   The reflective film according to claim 1, wherein the laminate is formed by an extrusion lamination method.   The reflective film according to any one of claims 1 to 5, wherein the aliphatic polyester resin is a lactic acid polymer.   The reflection film according to any one of claims 1 to 6, wherein a reflectance in a wavelength region of 550 nm is 95% or more.   A reflecting plate comprising the reflecting film according to claim 1.