JP5148089B2 - Aliphatic polyester resin reflective film and reflector - Google Patents

Description

  The present invention relates to an aliphatic polyester-based resin reflective film, and more particularly to a polyester-based resin reflective film used for a reflective plate of a liquid crystal display, a lighting fixture, a lighting signboard, and the like.

  JP-A-4-239540 discloses a film made of an aromatic polyester-based resin as a reflective film used for a reflection plate of a liquid crystal display or the like, but an aromatic ring contained in the molecular chain is an ultraviolet ray. Therefore, when exposed to ultraviolet rays, the reflective film deteriorates and yellows, and the reflectance of the reflective film decreases. Japanese Patent Application Laid-Open No. 11-174213 discloses a film made of a polypropylene resin as a reflection film. However, when the polypropylene resin is subjected to incineration when incinerated, the amount of heat generated by incineration is disclosed. There was a problem that the incinerator was damaged because of the large. In addition, since plastics such as polypropylene resins are stable in the natural environment for a long period of time, if landfilled during disposal, they will remain in the soil for a long period of time, promoting the shortening of the landfill disposal site, There were problems such as damaging the scenery of the wildlife and the living environment of wild animals and plants.

  Furthermore, a film made of a polypropylene-based resin to which 60% by mass or more of an inorganic filler is added cannot secure a sufficient film strength, so that the film is easily broken during stretching, and the stability of film production may be reduced. It was.

  Reflective films used for liquid crystal display reflectors, etc. are required to retain their shape when folded, etc., but conventional reflective films have “dead fold” properties. There was a drawback of being low.

JP-A-4-239540 JP-A-11-174213

    The present invention has been made to solve the above problems, and the object of the present invention is to prevent yellowing over time or decrease in reflectance due to use, and to have excellent deadfold properties. An object of the present invention is to provide a reflective film that generates a small amount of heat when incinerated and can be decomposed by microorganisms or the like when landfilled and does not cause disposal problems.

The aliphatic polyester-based resin reflective film of the present invention contains a fine powder filler, and has a gap so that the proportion of the void in the film is 50% or less (including the case where there is no void). It is characterized by having.
Here, it is preferable that the fine powder filler contains at least titanium oxide.
The titanium oxide preferably has a vanadium content of 5 ppm or less.
In this invention, the said fine powder filler can be contained in the range of 10 mass% or more and 60 mass% or less in the aliphatic polyester-type resin composition containing a fine powder filler and aliphatic polyester-type resin.
When the aliphatic polyester resin reflective film of the present invention has voids, the void ratio is preferably 5% or more and 50% or less.
In the present invention, the aliphatic polyester resin preferably has a refractive index of less than 1.50.
The difference between the refractive index of the aliphatic polyester resin and the refractive index of the fine powder filler is preferably 0.15 or more.
Further, the aliphatic polyester resin may be a lactic acid resin.
The aliphatic polyester-based resin reflective film of the present invention is a film obtained by melting and forming a resin composition containing an aliphatic polyester-based resin and a fine powder filler, at least in one axial direction so that the area magnification is 5 times or more. It can be a stretched film.
Moreover, the shrinkage ratio of the film after being stored at 80 ° C. for 3 hours is greater than 0% and less than 0.7% in the longitudinal direction, and is −0.1% or more and 0.5% or less in the lateral direction. Preferably there is.
The reflecting plate of the present invention is characterized by including any of the above aliphatic polyester resin reflecting films. For example, it can be formed by bonding to a metal plate or a resin plate, and can be used as a reflection plate for liquid crystal display, a reflection plate for lighting fixtures, a reflection plate for lighting signs, and the like.

As described above in detail, according to the present invention, the function of a conventional reflective film or sheet is sufficiently exhibited, and yellowing or reflectance does not decrease due to use, and the deadfold property is excellent. In addition, it generates a small amount of heat when incinerated, and can be decomposed by microorganisms etc. when it is landfilled (biodegradable), and does not cause disposal problems. A reflective film can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below.
The aliphatic polyester-based resin reflective film of the present invention has a fine powder filler inside.

  Examples of the fine powder filler used in the present invention include organic fine powder and inorganic fine powder. As the organic fine powder, it is preferable to use at least one selected from cellulose-based powders such as wood powder and pulp powder, polymer beads, polymer hollow particles, and the like.

  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 It is preferable to use 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 obtained film, those having a large difference in refractive index from the base resin constituting the film are preferable. That is, the inorganic fine powder preferably has a large refractive index. Specifically, it is more preferable to use calcium carbonate, barium sulfate, titanium oxide or zinc oxide having a refractive index of 1.6 or more, and it is particularly preferable to use titanium oxide among these. By using titanium oxide, it is possible to impart high reflection performance to the film with a smaller filling amount, and it is possible to obtain a film having high reflection performance even with a thin wall.

  In the present invention, it is particularly preferable to use high-purity titanium oxide having high purity among titanium oxides. In the present invention, high-purity titanium oxide is titanium oxide having a small light absorbing ability with respect to visible light and means a material having a small content of coloring elements such as vanadium, iron, niobium, copper, and manganese. In the present invention, titanium oxide having a vanadium content of 5 ppm or less in titanium oxide is referred to as high-purity titanium oxide. From the viewpoint of reducing the light absorption ability of high-purity titanium oxide, it is preferable to reduce coloring elements such as iron, niobium, copper, and manganese contained in titanium oxide.

  Examples of the titanium oxide used in the present invention include crystalline titanium oxides such as anatase type titanium oxide and rutile type titanium oxide. From the viewpoint of increasing the difference in refractive index from the base resin, titanium oxide having a refractive index of 2.7 or more is preferable. For example, a crystal form of rutile titanium oxide is preferably used.

  Examples of the titanium oxide having a vanadium content of 5 ppm or less include those produced 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 first generate 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.

  In the present invention, inorganic fine powder and organic fine powder may be used in combination as the fine powder filler. Moreover, fine powder fillers can be used together. For example, titanium oxide and other fine powder fillers, high-purity titanium oxide and other fine powder fillers may be used in combination.

  In addition, in order to improve the dispersibility of the fine powder filler in the resin, the surface of the fine powder filler is subjected to a surface treatment with a silicon compound, a polyhydric alcohol compound, an amine compound, a fatty acid, a fatty acid ester, or the like. You may use what you did. For example, in order to improve the dispersibility of titanium oxide in an aliphatic polyester-based resin and to suppress the photocatalytic activity of titanium oxide, surface treatment may be performed on the surface of titanium oxide.

  As the surface treatment agent, for example, at least one 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. These organic compounds can be used. Moreover, you may use combining these inorganic compounds and organic compounds.

  The fine powder filler used in the present invention preferably has a particle size of 0.05 μm or more and 15 μm or less, more preferably 0.1 μm or more and 10 μm or less. If the particle size of the 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. When the particle size is 15 μm or less, the formed voids are not roughened, and a film having a high reflectance can be obtained.

  The high purity titanium oxide used in the present invention preferably has a particle size of 0.1 μm or more and 1 μm or less, more preferably 0.2 μm or more and 0.5 μm or less. When the particle diameter of the high purity 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, if the particle diameter of high purity titanium oxide is 1 micrometer or less, since the interface of aliphatic polyester-type resin and titanium oxide is formed densely, high light reflectivity can be provided to a reflective film.

  The fine powder filler is preferably dispersed and blended in the aliphatic polyester resin. In the aliphatic polyester resin composition for forming the reflective film, the content of the fine powder filler contained in the reflective film of the present invention, considering the light reflectivity, mechanical properties, productivity, etc. of the film, It is preferably 10% by mass or more and 60% by mass or less, more preferably 10% by mass or more and less than 55% by mass, and particularly preferably 20% by mass or more and 50% by mass or less. If content of a fine powder filler is 10 mass% or more, the area of the interface of resin and a fine powder filler can fully be ensured, and high light reflectivity can be provided to a film. Moreover, if content of a fine powder filler is 60 mass% or less, the mechanical property required for a film can be ensured.

  The aliphatic polyester-based resin reflective film of the present invention has voids so that the void ratio (ratio of voids in the film) is 50% or less. The air gap here means not a through hole but a closed hole. However, most of the voids only need to be closed holes, and it does not mean that no through holes or open holes are recognized. In the present invention, an excellent reflectance can be realized by including a fine powder filler in a dispersed state effectively in the film.

  When the aliphatic polyester-based resin reflective film of the present invention has voids in the film, the proportion of the voids in the film (porosity) is preferably in the range of 5% or more and 50% or less. . Further, the porosity is more preferably 20% or more, and particularly preferably 30% or more. If the porosity exceeds 50%, the mechanical strength of the film may be reduced, and the film may be broken during film production, or durability such as heat resistance may be insufficient during use. For example, voids can be formed in the film by adding a fine powder filler and stretching.

  If titanium oxide is used as the fine powder filler, high light reflectivity can be achieved even if the porosity existing inside the film is small. For example, sufficiently high light reflectivity can be achieved even with a porosity of 15% or less. Can be achieved. This is presumably due to the high refractive index and high hiding power of titanium oxide. Further, if the amount of filler used can be reduced, the number of voids formed by stretching can be reduced, so that the mechanical properties of the film can be improved while maintaining high reflection performance. Furthermore, even if the filler is used in a large amount, the mechanical properties can be improved in the same manner by reducing the stretch amount and reducing the voids. These are also advantageous in improving the dimensional stability of the film. Moreover, if high reflection performance is ensured even if it is thin, it can be used, for example, as a reflective film for small and thin liquid crystal displays such as notebook personal computers and mobile phones.

Even if the aliphatic polyester-based resin reflective film of the present invention has no voids inside, it has high light reflectivity if it contains high-purity titanium oxide having a vanadium content of 5 ppm or less. be able to. In addition, if high-purity titanium oxide is contained and there are voids, particularly high reflectivity can be realized.
The base resin constituting the reflective film of the present invention preferably has a refractive index (n) of less than 1.50. In the present invention, an aliphatic polyester resin having a refractive index (n) of less than 1.50 is used. It is preferable to use it.

  The resin having a refractive index (n) of less than 1.50 is preferably an aliphatic resin not containing an aromatic ring, and more preferably a polylactic acid polymer. The thing containing an aromatic ring, for example, aromatic resin, has a refractive index of about 1.55 or more. A reflective film containing a fine powder filler in the film imparts light reflectivity by utilizing refractive scattering at the interface within the film. Therefore, higher light reflectivity can be easily imparted when the difference in refractive index between the resin constituting the film and the fine powder filler is larger. In the present invention, the difference in refractive index is preferably 0.15 or more, and more preferably 0.20 or more. If the refractive index of the resin constituting the film is less than 1.5, it is easy to ensure that the difference from the refractive index of the fine powder filler is 0.15 or more. For example, since the polylactic acid-based polymer has a refractive index of about 1.45, the condition that the difference from the fine powder filler or the like is 0.15 or more can be easily achieved, and the combined fine powder filler There are many types. However, since the resin containing an aromatic ring has a refractive index of about 1.55 or more, the difference in refractive index from the fine powder filler often becomes small.

The aliphatic polyester-based resin does not absorb ultraviolet rays because it does not contain an aromatic ring in the molecular chain. Therefore, the film is not deteriorated or yellowed by ultraviolet rays emitted from a light source such as a liquid crystal display device, and the light reflectivity is not lowered.
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-based resins include poly-ε-caprolactam obtained by ring-opening polymerization of lactone, polyethylene adipate obtained by polymerizing dihydrochloric acid and diol, polyethylene azelate, polytetramethylene succinate , Cyclohexanedicarboxylic acid / cyclohexanedimethanol condensate, etc., polylactic acid obtained by polymerizing hydroxycarboxylic acid, polyglycol, etc., and part of ester bonds of the above aliphatic polyester, for example, 50% or less are amide bonds, ethers Examples thereof include aliphatic polyesters substituted with bonds, urethane bonds, and the like. Examples of the aliphatic polyester resin fermented and synthesized by microorganisms include polyhydroxybutyrate, a copolymer of hydroxybutyrate and hydroxyvalerate, and the like.

  In the present invention, the polylactic acid polymer refers to a homopolymer of D-lactic acid or L-lactic acid or a copolymer thereof, and specifically, a poly (D-lactic acid) whose structural unit is D-lactic acid. ), Poly (L-lactic acid) whose structural unit is L-lactic acid, and poly (DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, and mixtures thereof are also included.

  Aliphatic polyester-based resins including polylactic acid-based polymers do not absorb ultraviolet rays because they do not contain an aromatic ring in the molecular chain. Therefore, since the reflective film is not deteriorated or yellowed by being exposed to ultraviolet rays, the reflectance of the film does not decrease.

  The polylactic 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, a polylactic acid polymer having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of D-lactic acid, L-lactic acid, or a mixture thereof. Further, in the ring-opening polymerization method, a 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. A lactic acid 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, A polylactic acid polymer having an arbitrary composition and crystallinity can be obtained by mixing and polymerizing these as necessary.

  In the polylactic acid polymer used in the present invention, the constituent 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: 100-15: 85, more preferably, D-lactic acid: L-lactic acid = 99.5: 0.5-95: 5, or D-lactic acid: L-lactic acid = 0.5: 99.5-5: 95. A polylactic acid polymer in which the composition ratio of D-lactic acid and L-lactic acid is 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. On the other hand, a polylactic acid polymer composed of D-lactic acid and L-lactic acid is preferable because flexibility is imparted and film forming stability and stretching stability are improved. Therefore, taking into consideration the balance between the heat resistance of the resulting reflective film, molding stability and stretching stability, the polylactic acid polymer used in the present invention has a composition ratio of D-lactic acid and L-lactic acid, It is more preferable that 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.

  In the present invention, polylactic acid polymers having different copolymerization ratios of D-lactic acid and L-lactic acid may be blended. In this case, what is necessary is just to make it the value which averaged the copolymerization ratio of D-lactic acid and L-lactic acid of a some lactic acid-type polymer in the said range. By blending a homopolymer of D-lactic acid and L-lactic acid and a copolymer, it is possible to balance the difficulty of bleeding and the expression of heat resistance.

  The polylactic acid polymer used in the present invention preferably has a high molecular weight. For example, the weight average molecular weight is preferably 10,000 or more, more preferably 60,000 or more and 400,000 or less, more preferably 100,000. As mentioned above, it is especially preferable that it is 300,000 or less. When the weight average molecular weight of the polylactic acid-based polymer is 10,000 or less, the obtained film may be inferior in mechanical properties.

  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, in-car small televisions, and the like, and those that can withstand high temperatures and high humidity have become necessary. Therefore, it is preferable to add a hydrolysis inhibitor to the aliphatic polyester-based resin reflective film for the purpose of imparting durability.

  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.

  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. 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. Moreover, if the addition amount of a carbodiimide compound is 3.0 mass parts or less, there will be little coloring of the film obtained and high light reflectivity will be acquired.

  In the present invention, an antioxidant, a light stabilizer, a heat stabilizer, a lubricant, a dispersant, a UV absorber, a white pigment, a fluorescent whitening agent, and other additions within a range not impairing the effects of the present invention. An agent can be added.

  The aliphatic polyester-based resin reflective film is preferably 90% or more, and more preferably 95% or more, in the light wavelength range of 420 nm to 700 nm. If the average reflectance of the film surface is 90% or more, good reflection characteristics are exhibited, and a screen such as a liquid crystal display can achieve sufficient brightness. The reflective film thus obtained has a predetermined reflectance that functions sufficiently as a reflective film. The aliphatic polyester resin reflective film of the present invention preferably has an average surface reflectance of 95% or more, more preferably 98% or more, for light having a wavelength of 550 nm. When the average reflectance is 95% or more, good reflection characteristics are exhibited, and sufficient brightness can be given to a screen such as a liquid crystal display.

  The aliphatic polyester-based resin reflective film of the present invention can maintain an excellent average reflectance even after being exposed to ultraviolet rays.

  By the way, in a car parked under the hot sun in summer, the car navigation system for automobiles, the in-vehicle small television, etc. are exposed to high temperatures. Further, when the liquid crystal display device is used for a long time, the periphery of the light source lamp is exposed to a high temperature. Therefore, a reflective film used for a liquid crystal display such as a car navigation system or a liquid crystal display device is required to have a heat resistance of about 110 ° C. That is, when the reflective film is allowed to stand at a temperature of 120 ° C. for 5 minutes, the thermal contraction rate of the film is preferably 10% or less, and more preferably 5% or less. If the heat shrinkage rate of the film is greater than 10%, it may shrink over time when used at high temperatures, and if the reflective film is laminated on a steel plate or the like, only the film may be deformed. . A film that has undergone large shrinkage has a smaller surface that promotes reflection, and the voids inside the film are smaller, so the reflectivity decreases.

  In order to prevent thermal shrinkage, it is desirable to completely proceed with crystallization of the film. Since it is difficult for the aliphatic polyester-based resin reflective film to be completely crystallized only by biaxial stretching, in the present invention, it is preferable to perform heat setting after stretching. By promoting crystallization of the film, heat resistance can be imparted to the film and hydrolysis resistance can be improved.

  In recent years, there has been an increasing need for an increase in the size of liquid crystal displays and the like, and an increase in the size of reflection sheets has also been demanded. For example, when it is incorporated as a reflective sheet for a large-screen liquid crystal television or the like, it is used for a long time while being exposed to a light source. Further, even in the case of medium-sized and small-sized edge light type displays, when the end portions are regulated, those having a small dimensional change are required. For example, the heat shrinkage ratio after holding at 80 ° C. for 180 minutes is such that the shrinkage ratio in the longitudinal direction is greater than 0% and less than 0.7%, and the shrinkage ratio in the transverse direction is −0.1% to 0.5%. % Is preferred. The shrinkage in the lateral direction is preferably 0.001% to 0.3%, but more preferably. Here, the longitudinal direction is the same direction as the film flow direction (take-off direction), and the horizontal direction is a direction perpendicular to the film flow direction.

  Therefore, it is preferable that the aliphatic polyester-based resin reflective film of the present invention has a heat shrinkage rate within the above range after being held at 80 ° C. for 180 minutes. If the heat shrinkage rate of the reflective film can be within such a range, even when used on the back of a large liquid crystal television or the like, deformation due to aging can be prevented and the flatness of the film can be maintained. For example, after the film has been stretched, the heat shrinkage rate of the film can be set within the above range by subsequently performing a relaxation treatment at the tenter outlet and applying a predetermined amount of relaxation.

  The aliphatic polyester-based resin reflective film of the present invention can be decomposed by microorganisms or the like when it is landfilled, and does not cause a problem in disposal. When the aliphatic polyester-based resin is landfilled, the ester bond portion is hydrolyzed to reduce the molecular weight to about 1,000, and subsequently biodegraded by microorganisms in the soil.

  On the other hand, aromatic polyester resins have high intramolecular bond stability, and hydrolysis of the ester bond portion hardly occurs. In addition, hydrolysis cannot occur in the polypropylene resin. Therefore, even if the aromatic polyester-based resin and the polypropylene-based resin are landfilled, the molecular weight does not decrease and biodegradation by microorganisms or the like does not occur. As a result, there are problems such as remaining in the soil for a long time, promoting the shortening of the landfill site for waste disposal, and damaging the natural landscape and the living environment of wild animals and plants.

  Below, although an example is given and demonstrated about the manufacturing method of the aliphatic polyester-type resin reflective film of this invention, it is not limited to the following manufacturing method at all.

  First, an aliphatic polyester resin composition is prepared by blending an aliphatic polyester resin with a fine powder filler and / or high-purity titanium oxide, a hydrolysis inhibitor, and other additives as required. Specifically, a fine powder filler or high-purity titanium oxide, a hydrolysis inhibitor and the like are added to the aliphatic polyester-based resin as necessary, mixed with a ribbon blender, tumbler, Henschel mixer, etc., then a Banbury mixer, An aliphatic polyester resin composition can be obtained by kneading 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 polylactic acid) using a single screw or twin screw extruder. Alternatively, an aliphatic polyester resin composition can be obtained by adding a predetermined amount of an aliphatic polyester resin, a fine powder filler or high-purity titanium oxide, a hydrolysis inhibitor, or the like with a separate feeder or the like. Alternatively, a so-called master batch in which a fine powder filler or high-purity titanium oxide, a hydrolysis inhibitor, etc. are blended in a high concentration in an aliphatic polyester resin is prepared in advance, and this master batch and the aliphatic polyester resin To obtain an aliphatic polyester resin composition having a desired concentration.

  Next, the aliphatic polyester resin composition thus obtained is melted and formed into a film. For example, after the aliphatic polyester resin composition is dried, 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 an aliphatic polyester-type 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, in the case of polylactic acid, the extrusion temperature is preferably in the range of 170 ° C to 230 ° C. . Thereafter, the molten aliphatic polyester-based resin composition is extruded from the slit-shaped discharge port of the T die, and is solidified on a cooling roll to form a cast sheet.

  The aliphatic polyester resin reflective film of the present invention is preferably stretched in at least a uniaxial direction, and more preferably stretched in a biaxial direction. Depending on the stretching conditions, it may be difficult to impart the function of the reflective film, and sufficient heat resistance may not be imparted, so the stretching conditions are important.

  When the aliphatic polyester-based resin reflective film of the present invention has voids, the obtained cast sheet is preferably stretched 5 times or more in area magnification, and more preferably 7 times or more. By stretching to 5 times or more in the area magnification, a porosity of 5% or more can be realized, and by stretching to 7 times or more, a porosity of 20% or more can be realized, and 7.5 times or more. A porosity of 30% or more can also be realized by stretching the film. For example, a film having a porosity of 5% or more can be obtained by using titanium oxide as a fine powder filler and stretched 5 times or more in area magnification, and the film is whitened and has sufficient film reflectivity. Is obtained. In addition, when using fillers other than a titanium oxide as a fine powder filler, it is preferable to make it a porosity become 20% or more.

  When it is difficult to realize an area magnification of 5 times or more by uniaxial stretching alone, an area magnification of 5 times or more can be easily achieved by biaxial stretching. That is, by biaxially stretching, a film having a higher porosity can be stably obtained, and as a result, the reflectance of the film can be improved. In addition, since the mechanical strength of the film can be increased by biaxially stretching the film, biaxial stretching is also preferred from the viewpoint of the mechanical properties of the film. Moreover, when heat resistance is required for the reflective film, biaxial stretching is preferable because anisotropy is lost in the shrinking direction of the film.

By the way, when high-purity titanium oxide is used, it is preferably stretched 1.1 times or more in at least a uniaxial direction, and more preferably stretched in a biaxial direction. However, since the presence of a void is not essential, a void may or may not be formed.
For example, in the case of polylactic acid, the stretching temperature when stretching the cast sheet is preferably 50 ° C. or higher and 90 ° C. or lower. If the stretching temperature is 50 ° C. or higher, the film does not break during stretching, and if it is 90 ° C. or lower, the stretching orientation is lowered and the porosity is not reduced.

  For example, by appropriately selecting the draw ratio and the like, and stretching the aliphatic polyester resin film of the present invention, voids are formed inside the film. This is because the aliphatic polyester resin and the fine powder filler are stretched during stretching. This is because the stretching behavior is different. In other words, if the stretching is performed at a stretching temperature suitable for the aliphatic polyester resin, the aliphatic polyester resin serving as the matrix is stretched, but the fine powder filler tries to remain as it is, so the aliphatic polyester resin. And the fine powder filler are peeled off to form voids. By only uniaxially stretching the film, the voids formed can only be in a fibrous form extending in one direction, but by biaxially stretching, the voids are stretched in both the vertical and horizontal directions and become a disk-like form. . In other words, biaxial stretching increases the peeling area at the interface between the aliphatic polyester resin and the fine powder filler, and the whitening of the film proceeds. As a result, the reflectance as a reflective film is good. It is obtained.

  The stretching order of biaxial stretching is not particularly limited. For example, simultaneous biaxial stretching or sequential stretching may be used. After melt film formation using a stretching facility, the film may be stretched in the MD direction by roll stretching, and then stretched in the TD direction by tenter stretching, or biaxial stretching may be performed by tubular stretching or the like.

  In the present invention, in order to impart heat resistance and dimensional stability to the aliphatic polyester-based resin reflective film, it is preferable to perform heat setting after stretching.

  The treatment temperature for heat-setting the film is preferably 90 to 160 ° C, more preferably 110 to 140 ° C. The processing time required for heat setting is preferably 1 second to 5 minutes. Moreover, although there is no limitation in particular about extending | stretching equipment etc., it is preferable to perform the tenter extending | stretching which can perform a heat setting process after extending | stretching.

  The thickness of the aliphatic polyester-based resin reflective film of the present invention is not particularly limited, but is usually 30 μm to 500 μm, and is preferably in the range of about 50 μm to 500 μm in view of practical handling. In particular, as a reflective film for small and thin reflectors, the thickness is preferably 30 μm to 100 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.

  In addition, the reflective film of the present invention may have a single layer configuration, but may also have a multilayer configuration in which two or more layers are laminated.

  Moreover, the reflector used for a liquid crystal display etc. can be formed using the aliphatic polyester-type resin reflective film of this invention. For example, a reflective plate can be formed by coating an aliphatic polyester-based resin reflective film on a metal plate or a resin plate. This reflecting plate is useful as a reflecting plate used for liquid crystal display devices, 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 fusion 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, a reflective film can be bonded by applying an adhesive such as polyester, polyurethane, or epoxy to the surface of the metal plate or resin plate on the side where the reflective film is bonded. In this method, using commonly used coating equipment such as a reverse roll coater and a kiss roll coater, the adhesive film thickness after drying on the surface of a metal plate or the like to which the reflective film is bonded is about 2 to 4 μm. Apply an adhesive so that Next, the coated surface is dried and heated by an infrared heater and a hot-air heating furnace, and while maintaining the surface of the plate at a predetermined temperature, the reflective film is directly coated and cooled using a roll laminator, thereby reflecting the reflective plate Can get. In this case, it is preferable to keep the surface of the metal plate or the like at 210 ° C. or lower because the light reflectivity of the reflecting plate can be maintained high.

In the present invention, a sheet is thin by definition in JIS, and generally refers to a flat product whose thickness is small instead of length and width. By the way, the 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). JIS K 6900). Therefore, it can be said that a sheet having a particularly thin thickness is a film, but the boundary between the sheet and the film is not clear and is difficult to distinguish clearly. ", And even when referred to as" sheet "," film "is also included.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention. In addition, the measured value and evaluation which are shown to an Example were performed as shown below. Here, the film take-up (flow) direction is indicated by MD, and its orthogonal direction is indicated by TD.

(Measurement and evaluation method)
(1) Average particle diameter Using a powder specific surface measuring instrument (transmission method) of model “SS-100” manufactured by Shimadzu Corporation, a sample tube having a cross-sectional area of 2 cm ² and a height of 1 cm is filled with 3 g of sample. The air permeation time of 20 cc with a 500 mm water column was calculated.

(2) Thermal contraction rate Thermal contraction rate a:
A 100 mm wide marked line was put on each of MD and TD of the film, and cut out as a sample. The cut sample film was placed in a hot air circulating oven at a temperature of 120 ° C. and held for 5 minutes, and then the amount of shrinkage of the film was measured. The ratio of the shrinkage amount to the original size (100 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 (%).

Thermal contraction rate b:
A 200 mm wide marked line was put in each of MD and TD of the film, and cut out as a sample. The cut out sample film was put 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 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) Porosity (%)
Measure the density of the film before stretching (denoted as “unstretched film density”) and the density of the film after stretching (denoted as “stretched film density”), and assign it to the following formula to determine the porosity of the film. Asked.

Porosity (%) =
{(Unstretched film density−Stretched film density) / Unstretched film density} × 100

(4) Average reflectance (%)
Average reflectance a (wavelength 400 to 700 nm):
An integrating sphere is attached to a spectrophotometer ("U-4000", manufactured by Hitachi Instruments Service Co., Ltd.), and the reflectance when the barium sulfate white plate is 100% is measured at a wavelength of 400 nm to 700 nm at 20 nm intervals. The average value of the measured values obtained was calculated, and this value was defined as the average reflectance at a wavelength of 400 to 700 nm.

Average reflectance b (wavelength 420 to 700 nm):
Measured in the same manner as the above average reflectance a, among the obtained measured values, the measured value at a wavelength of 420 to 700 nm was used to calculate the average value of this value, and this value was calculated as the average reflectance at a wavelength of 420 to 700 nm. It was.

(5) Reflectance (%)
An integrating sphere was attached to a spectrophotometer (“U-4000”, manufactured by Hitachi Instrument Service Co., Ltd.), and the reflectance with respect to light having a wavelength of 550 nm was measured. However, the barium sulfate white plate was 100%.

(6) Hydrolysis resistance The weight of the aliphatic polyester resin constituting the film after leaving the film for 300 hours or 1,000 hours in a constant temperature and humidity chamber maintained at a temperature of 60 ° C. and a relative humidity of 95% RH. Average molecular weight was measured. The measured value was substituted into the following formula to obtain the molecular weight retention rate (%), and the hydrolysis resistance was evaluated based on the following evaluation criteria. However, the symbols “◯” and “Δ” are above the practical level.

Molecular weight retention (%) =
(Weight average molecular weight after standing / weight average molecular weight before standing) × 100

Evaluation criteria:
○ When the molecular weight retention is 90% or more △ When the molecular weight retention is 60% or more and less than 90% × When the molecular weight retention is less than 60%

(7) Yellowing prevention property The film is irradiated with ultraviolet rays for 1,000 hours in a sunshine weather meter tester, or for 180 hours in a xenon 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”.
Moreover, also about the film after ultraviolet irradiation, the average reflectance (%) was calculated | required according to the measuring method of said (4), and the reflectance (%) was calculated | required according to the measuring method of said (5).

(8) Biodegradability It was performed based on the following evaluation criteria.

Evaluation criteria:
× For films that can be biodegraded by landfill processing ○ For films that cannot be biodegraded by landfill processing

(9) Deadfold property A sample film having a width of 20 mm and a length of 150 mm is cut out with the longitudinal direction of the film as the width direction and the orthogonal direction as the length direction. One short side of the sample film is held, and the other short side (the other end) that is not held is located at a position 30 mm from the other end, and the straight line at this position is a fold mountain (or a fold valley). Bend 180 degrees so that a load of 0.15 MPa is applied. After applying a load of 0.15 MPa for 0.5 seconds, immediately remove the load, open the folded part and return the other end to the original position by hand, release the hand, and then hold the angle held by bending. taking measurement. That is, the protractor measures the angle at which the other end is separated from the original position when the hand is released. This value is 180 degrees at the maximum and 0 degree at the minimum. The larger this value, the better the deadfold property.

(10) Difference between the refractive index of the resin and the refractive index of the fine powder filler The refractive index (n1) of the resin is measured based on the method A of JIS K-7142, and the refractive index of the fine powder filler (n2). Was measured based on the method B of JIS K-7142. However, the polyethylene terephthalate as the resin component in Comparative Example 1 and the polymethylpentene as the filler component were obtained based on the method A of JIS K-7142 after forming into a film shape, and the filler component The calcium carbonate as was obtained based on the method B of JIS K-7142.

(11) Film-forming property When film-forming, it evaluated whether troubles, such as a film fracture | rupture generate | occur | produced. However, the evaluation criteria are as follows.

Evaluation criteria:
○ The film can be stably formed and has good film forming properties.
X: Film breakage sometimes occurs or film breakage occurs frequently, resulting in poor film forming properties.

(12) Vanadium concentration in titanium oxide (ppm)
Nitric acid (10 mL) was added to titanium oxide (0.6 g) and decomposed in a microwave ashing apparatus for 80 minutes, and the obtained solution was measured using an ICP emission spectroscopic analyzer.

(13) Reflector plate workability Three items of right-angle bending (R = 0 mm), screw contact bending, and well-type Eriksen (5 mm) were evaluated based on the following evaluation criteria.

Evaluation criteria:
〇 Film peeling does not occur × Film peeling occurs

(14) Reflective plate reflectivity With respect to the reflective plate, the reflectance (%) was measured using the same measurement method as in (5) above.

(15) Practical evaluation test The fixed frame of the reflective sheet incorporated in the backlight of Hitachi, Ltd. 21-inch liquid crystal television was used. After being attached to this fixed frame in the same manner as actually attached to the liquid crystal television and heated at 80 ° C. for 3 hours, the appearance of the sheet was observed with the naked eye and evaluated based on the following criteria.

Evaluation criteria:
A There is no change in the appearance of the film after heating. B The film after heating is visually observed, but there are irregularities with a height of less than 0.5 mm that cannot be measured. C The film after heating. Irregularities with a height of less than 1 mm can be seen. D Irregularities with a height of 1 mm or more can be seen in the heated film.

The definition of the relaxation rate is as follows: Lateral relaxation rate = (film width after relaxation) / (film width before relaxation)
Longitudinal relaxation rate = (film speed before relaxation) / (film speed after relaxation)

  The polylactic acid polymer used in the examples was produced as follows.

[Production of polylactic acid-based polymer (PLA) (1): L-form content 99.5%]
What added 15 ppm of tin octylates to 100 kg of L-lactide (trade name: PURASORB L) manufactured by Pulac Japan Co., Ltd. was placed in a 500 L batch polymerization tank equipped with a stirrer and a heating device. Subsequently, nitrogen substitution was performed, and polymerization was performed for 60 minutes under the conditions of a temperature of 185 ° C. and a stirring speed of 100 rpm to obtain a melt. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents and extruded into a strand at 200 ° C. while devolatilizing at a vent pressure of 4 Torr. A polylactic acid polymer was obtained.

  The obtained polylactic acid polymer had a weight average molecular weight of 200,000, an L-form content of 99.5%, and a D-form content of 0.5%. Moreover, the glass transition temperature (Tg) was 65 degreeC.

Example I
(Example I-1)
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and calcium carbonate having an average particle size of 0.15 μm A mixture was formed by mixing at a mass percentage. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of the mixture, the mixture was pelletized using a twin screw extruder to prepare a so-called master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 40% by mass to 60% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T die at 230 ° C. using a single screw extruder, and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction at a temperature of 65 ° C., and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, heat shrinkage rate a, porosity, average reflectance a before ultraviolet irradiation and average reflectance a after ultraviolet irradiation (wavelength 400 to 700 nm), hydrolysis resistance, yellowing prevention property (sunshine) Ultraviolet irradiation time with a weather meter was 1,000 hours), and biodegradability and deadfold properties were measured and evaluated. The results are shown in Tables 1 and 2.

(Example I-2)
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and barium sulfate having an average particle size of 0.7 μm A mixture was formed by mixing at a weight percentage. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 50% by mass / 50% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T die at 230 ° C. using a single screw extruder, and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction at a temperature of 65 ° C., and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example I-1 were performed. The results are shown in Tables 1 and 2.

(Example I-3)
60% / 40% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and calcium carbonate having an average particle size of 5 μm To form a mixture. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. The master batch and the polylactic acid polymer (1) were mixed at a ratio of 60% by mass / 40% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 230 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 3, and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example I-1 were performed. The results are shown in Tables 1 and 2.

(Example I-4)
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and barium sulfate having an average particle size of 0.7 μm A mixture was formed by mixing at a mass percentage. This mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 50% by mass / 50% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T die at 230 ° C. using a single screw extruder, and solidified by cooling to form a film. As shown in Table 1, the obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction, and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm, as shown in Table 1. It was. About the obtained reflective film, the same measurement and evaluation as Example I-1 were performed. The results are shown in Tables 1 and 2.

(Comparative Example I-1)
Polyethylene terephthalate and barium sulfate having an average particle size of 0.7 μm were mixed at a ratio of 50% by mass / 50% by mass to form a mixture. This mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and polyethylene terephthalate were mixed at a ratio of 50% by mass / 50% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 280 ° C. using a single screw extruder and cooled and solidified to form a film. As shown in Table 1, the obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction, and then heat treated at 235 ° C. to obtain a reflective film having a thickness of 188 μm, as shown in Table 1. It was. About the obtained reflective film, the same measurement and evaluation as Example I-1 were performed. The results are shown in Tables 1 and 2.

(Comparative Example I-2)
Polypropylene and barium sulfate having an average particle diameter of 0.7 μm were mixed at a ratio of 50% by mass / 50% by mass to form a mixture. This mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and polypropylene were mixed at a ratio of 50% by mass / 50% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 210 ° C. using a single screw extruder and solidified by cooling to form a film. As shown in Table 1, the obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example I-1 were performed. The results are shown in Tables 1 and 2.

  As is clear from Tables 1 and 2, the reflective films of the present invention of Examples I-1 to I-3 have a porosity of 30% or more, heat shrinkability, average reflectance, hydrolysis resistance, yellow It was found that excellent results were obtained in all of the anti-deformation property, biodegradability, and deadfold property. Although Example I-4 which did not mix a hydrolysis inhibitor is slightly inferior in hydrolysis resistance, it is at a practical level, and all other evaluations are excellent.

On the other hand, it was found that Comparative Examples I-1 and I-2 formed from a resin other than the aliphatic polyester resin were inferior in the deadfold property and the biodegradability. In addition, it was confirmed that Comparative Example I-1 formed from a resin having an aromatic ring turned yellow by irradiation with ultraviolet rays, and the reflectance was greatly reduced from the initial value.

Example II
Example II-1
50% by mass / 50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and calcium carbonate having an average particle diameter of 5 μm To form a mixture. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. The master batch and the polylactic acid polymer (1) were mixed at a ratio of 60% by mass / 40% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 230 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 3, and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, heat shrinkage rate a, porosity, average reflectance b before ultraviolet irradiation and average reflectance b after ultraviolet irradiation (wavelength 420 to 700 nm), hydrolysis resistance, yellowing prevention property (sunshine) Ultraviolet irradiation time with a weather meter was 1,000 hours), and biodegradability and deadfold properties were measured and evaluated. The results are shown in Tables 3 and 4.

Example II-2
50% by mass of a pellet of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and titanium oxide having an average particle size of 0.25 μm A mixture was formed by mixing at a mass percentage. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 40% by mass / 60% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 230 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 3, and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example II-1 were performed. The results are shown in Tables 3 and 4.

Example II-3
In Example II-2, as shown in Table 3, a reflective film was produced in the same manner as in Example II-2 except that the thickness of the film was 250 μm. That is, in the same manner as in Example II-2, the film was extruded from a T-die and cooled and solidified to form a film, and then stretched and heat-treated in the same manner as in Example II-2 to form a reflective film having a thickness of 250 μm. Obtained. About the obtained reflective film, the same measurement and evaluation as Example II-1 were performed. The results are shown in Tables 3 and 4.

Example II-4
In Example II-2, as shown in Table 3, a reflective film was produced in the same manner as in Example II-2 except that the thickness of the film was 80 μm. That is, in the same manner as in Example II-2, the film was extruded from a T-die and cooled and solidified to form a film. Thereafter, the film was stretched and heat-treated in the same manner as in Example II-2 to form a reflective film having a thickness of 80 μm. Obtained. About the obtained reflective film, the same measurement and evaluation as Example II-1 were performed. The results are shown in Tables 3 and 4.

(Example II-5)
50% by mass of a pellet of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and titanium oxide having an average particle size of 0.25 μm A mixture was formed by mixing at a mass percentage. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. The master batch and the polylactic acid polymer (1) were mixed at a ratio of 60% by mass / 40% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 230 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 3, and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 80 μm. About the obtained reflective film, the same measurement and evaluation as Example II-1 were performed. The results are shown in Tables 3 and 4.

  As is apparent from Tables 3 and 4, the reflective films of Examples I-1, I-2 and Examples II-1 to II-5 have an average reflectance, hydrolysis resistance, yellowing resistance, It was found that excellent results were obtained in all of the degradability and the deadfold property. In particular, Examples II-2 to II-5 using titanium oxide as a fine powder filler were found to exhibit excellent average reflectance, yellowing prevention property, etc. even when the porosity was small.

  Example I-4, which was not mixed with an anti-hydrolysis inhibitor, was slightly inferior in hydrolysis resistance, but it was above the practical level, and showed excellent results for all but hydrolysis resistance. It was.

  On the other hand, Comparative Examples I-1 and I-2 made of a resin other than the aliphatic polyester resin are inferior in deadfold property and biodegradability, and Comparative Example I-1 made of a resin having an aromatic ring Was found to turn yellow by UV irradiation.

Example III
Example III-1
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and calcium carbonate having an average particle size of 0.15 μm After mixing at a ratio of mass%, the mixture was pelletized using a twin screw extruder to prepare a so-called master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 60% by mass: 40% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 220 ° C. using a single screw extruder and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction at a temperature of 65 ° C., and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. The obtained reflective film was measured and evaluated for porosity, average reflectance b before ultraviolet irradiation, average reflectance b after ultraviolet irradiation, yellowing prevention (ultraviolet irradiation time 180 hours), and film-forming property. It was. The results are shown in Tables 5 and 6.

Example III-2
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and barium sulfate having an average particle size of 0.7 μm After mixing at a ratio of% by weight, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 80% by mass / 20% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 220 ° C. using a single screw extruder and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction at a temperature of 65 ° C., and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example III-1 were performed. The results are shown in Tables 5 and 6.

Example III-3
50% by mass of a pellet of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and titanium oxide having an average particle size of 0.25 μm After mixing at a mass% ratio, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 40% by mass / 60% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 220 ° C. using a single screw extruder and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 5 at a temperature of 65 ° C. and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example III-1 were performed. The results are shown in Tables 5 and 6.

(Example III-4)
50% by mass of pellets of polylactic acid polymer (1) having a weight average molecular weight of 200,000 (D-form content: 0.5%, glass transition temperature: 65 ° C.) and zinc oxide having an average particle size of 0.4 μm After mixing at a mass% ratio, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the polylactic acid polymer (1) were mixed at a ratio of 40% by mass / 60% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 220 ° C. using a single screw extruder and solidified by cooling to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3 times in the TD direction as shown in Table 5 at a temperature of 65 ° C. and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example III-1 were performed. The results are shown in Tables 5 and 6.

(Comparative Example III-1)
For reference, commercial products were evaluated. That is, a reflective sheet “Lumirror E60L” having a thickness of 188 μm manufactured by Toray Industries, Inc. was prepared. About this reflection sheet, the same measurement and evaluation as Example 1 were performed. The results are shown in Tables 5 and 6.

(Comparative Example III-2)
Polypropylene and barium sulfate having an average particle diameter of 0.7 μm were mixed at a ratio of 50% by mass / 50% by mass to form a mixture. This mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and the barium sulfate were mixed so that the sulfuric acid concentration was 60% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 210 ° C. using a single screw extruder and solidified by cooling to form a film. The obtained film was uniaxially stretched 7 times in the MD direction as shown in Table 5 at a temperature of 135 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example III-1 were performed. The results are shown in Tables 5 and 6.

  In addition, the same measurement and evaluation as Example III-1 were performed also about the reflective film obtained in the above-mentioned comparative example I-1. The results are shown in Tables 5 and 6.

  As is apparent from Tables 5 and 6, the reflective films of the present invention of Examples III-1 to III-4 have a refractive index of the resin as the main component of less than 1.50, average reflectance, and prevention of yellowing. As a result, it was found that excellent results in film forming properties and film forming properties were obtained. In addition, the reflective films of Examples III-1 to III-4 were biodegradable. Therefore, when landfilled, it can be decomposed by microorganisms or the like (biodegradable) and does not cause disposal problems.

  On the other hand, Comparative Examples III-1 to III-2 and Comparative Example I-1 comprising a resin composition mainly composed of PET or PP, which is a resin having a refractive index of 1.50 or more, are inferior in biodegradability. It was what was. In addition, at least one of these evaluation results is poor. For example, Comparative Example III-1 and Comparative Example I-1 are inferior in yellowing prevention property, and Comparative Example III-2 is inferior in film forming property. It was.

Example IV
(Example IV-1)
Pellets of polylactic acid polymer having a weight average molecular weight of 200,000 (“Nature Works 4032D” manufactured by Cargill Dow Polymer Co., Ltd .: D-form content of 0.5%, glass transition temperature of 65 ° C.), and an average particle diameter of 0.25 μm Of titanium oxide (“Taipeke PF-739” manufactured by Ishihara Sangyo Co., Ltd., rutile-type crystalline titanium oxide) was mixed at a ratio of 50 mass% / 50 mass% to form a mixture. Hereinafter, Nature Works 4032D is referred to as “NW4032D”. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of the mixture, the mixture was pelletized using a twin screw extruder to prepare a so-called master batch. This master batch and polylactic acid polymer (NW4032D) were mixed at a ratio of 40% by mass to 60% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 220 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 2.5 times in the MD direction and 2.8 times in the TD direction at a temperature of 65 ° C. and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, porosity, reflectance of light having a wavelength of 550 nm before ultraviolet irradiation, reflectance of light having a wavelength of 550 nm after ultraviolet irradiation, hydrolysis resistance, yellowing prevention property (ultraviolet irradiation time is 1, 000 hours), biodegradability, deadfold property, reflector workability, and reflector reflectivity were measured and evaluated. The results are shown in Table 7 and Table 8.

(Example IV-2)
In Example IV-1, titanium oxide was changed from “Taipeku PF-739” manufactured by Ishihara Sangyo Co., Ltd. to titanium oxide having an average particle size of 0.25 μm (“Taipek CR-90-2” manufactured by Ishihara Sangyo Co., Ltd.). A reflective film having a thickness of 188 μm was produced in the same manner as in Example IV-1, except that the rutile type crystal form titanium oxide was changed. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-3)
In Example IV-1, the titanium oxide was changed from “Taipeke PF-739” manufactured by Ishihara Sangyo Co., Ltd. to titanium oxide having an average particle size of 0.25 μm (“Taipeke PF711” manufactured by Ishihara Sangyo Co., Ltd., rutile crystal form). A reflective film having a thickness of 188 μm was produced in the same manner as in Example IV-1, except that the titanium oxide was changed. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-4)
In Example IV-1, a reflective film having a thickness of 250 μm was produced in the same manner as in Example IV-1, except that the thickness of the film was changed to 250 μm. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-5)
In Example IV-1, Example IV-1 was changed except that the stretching ratio of the film was changed to stretch 3 times in the MD direction and 3.2 times in the TD direction, and the thickness of the film was changed to 80 μm. In the same manner as in Example 1, a reflective film having a thickness of 80 μm was produced. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-6)
“NW4032D” pellets and titanium oxide having an average particle size of 0.25 μm (“Taipaque PF-739” manufactured by Ishihara Sangyo Co., Ltd.) were mixed at a ratio of 50 mass% / 50 mass% to form a mixture. . After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of this mixture, the mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and polylactic acid polymer (NW4032D) were mixed at a ratio of 60% by mass: 40% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T-die at 220 ° C. using a single screw extruder, and cooled and solidified to form a film. The obtained film was biaxially stretched 3 times in the MD direction and 3.2 times in the TD direction at a temperature of 65 ° C. and then heat treated at 140 ° C. to obtain a reflective film having a thickness of 80 μm. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Table 7 and Table 8.

(Comparative Example IV-1)
Polyethylene terephthalate pellets and titanium oxide having an average particle size of 0.25 μm (“Taipeke PF-739” manufactured by Ishihara Sangyo Co., Ltd.) were mixed at a ratio of 50 mass% / 50 mass% to form a mixture. This mixture was pelletized using a twin screw extruder to prepare a master batch. This master batch and polyethylene terephthalate were mixed at a ratio of 40% by mass to 60% by mass to prepare a resin composition. Thereafter, the resin composition was extruded from a T-die at 280 ° C. using a single screw extruder and cooled and solidified to form a film. The obtained film was biaxially stretched 2.5 times in the MD direction and 2.8 times in the TD direction at a temperature of 90 ° C., and then heat-treated at 140 ° C. to obtain a reflective film having a thickness of 188 μm. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Table 7 and Table 8.

(Example IV-7)
In Example IV-1, titanium oxide was changed from “Taipaque PF-739” manufactured by Ishihara Sangyo Co., Ltd. to titanium oxide having an average particle size of 0.25 μm (“TITANIX JR-805” manufactured by Teika Co., Ltd.) A reflective film having a thickness of 188 μm was produced in the same manner as in Example IV-1, except that the material was changed to (titanium). About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-8)
In Example IV-1, titanium oxide was changed from “Taipaque PF-739” manufactured by Ishihara Sangyo Co., Ltd. to titanium oxide having an average particle size of 0.25 μm (“KRONOS KR470” manufactured by Titanium Industry Co., Ltd., rutile crystal form). A reflective film having a thickness of 188 μm was produced in the same manner as in Example IV-1, except that the titanium oxide was changed. About the obtained reflective film, the same measurement and evaluation as Example IV-1 were performed. The results are shown in Tables 7 and 8.

(Example IV-9)
The reflective film obtained in Example IV-1 was bonded to a galvanized steel plate (thickness 0.45 mm) to produce a reflective plate. That is, first, a polyester-based adhesive (commercially available product) was applied to the bonded surfaces of the steel plates so that the thickness after drying was 2 to 4 μm. Next, the coated surface is dried and heated using an infrared heater and a hot air heating furnace, and while maintaining the surface temperature of the steel sheet at 180 ° C., the roll film laminator is used to directly bond and cool the reflective film. A reflection plate was produced. About the obtained reflecting plate, the workability of the reflecting plate and the reflectance of the reflecting plate were measured and evaluated. The results are shown in Table 9.

(Example IV-10)
In Example IV-9, a reflecting plate was produced in the same manner as in Example IV-9, except that the surface temperature of the steel sheet was maintained at 220 ° C. instead of maintaining the surface temperature at 180 ° C. About the obtained reflecting plate, the same measurement and evaluation as Example IV-9 were performed. The results are shown in Table 9.

  As is clear from Tables 7 and 8, the reflective films of Example IV-1 to Example IV-8 maintain a reflectance of 90% or more even after ultraviolet irradiation, and have high light reflectivity and yellowing prevention. It was found to have Moreover, it turned out that it is excellent in hydrolysis resistance, deadfold property (shape retention), and has biodegradability. In particular, Examples IV-1 to IV-6 using titanium oxide having a vanadium content of 5 ppm or less have a high initial reflectance of 98% or more, and have a small decrease in reflectance after ultraviolet irradiation ( 2% or less), and the reflectance after ultraviolet irradiation was found to be excellent, maintaining 96% or more.

  IV-5 to IV-6 can achieve a very high reflectivity even with a thin film thickness of 80 μm, which is sufficient as a reflective film for small and thin liquid crystal displays such as notebook computers and mobile phones. It was possible to cope with.

  On the other hand, it was found that the reflective film of Comparative Example IV-1 obtained by mixing titanium oxide with PET was inferior in yellowing prevention property and deadfold property (shape retention).

  Further, as is apparent from Table 9, it was found that the reflective plates of Examples IV-9 and IV-10 maintained the adhesion required for processing and high light reflectivity.

  In addition, it turned out that the direction of the reflective plate of Example IV-9 is more excellent in the maintenance of light reflectivity than the reflective plate of Example IV-10. In recent years, reflecting plates for liquid crystal displays have been required to increase the performance of backlight units by supplying as much light as possible to the liquid crystal due to the demand for larger screens and higher display performance. Performance may be required. These reflective films can achieve such a high reflective performance.

Example V
Example V-1
A pellet of polylactic acid polymer having a weight average molecular weight of 200,000 (“NW4032D” manufactured by Cargill Dow) and titanium oxide having an average particle diameter of 0.25 μm were mixed at a ratio of 50 mass% / 50 mass%. A mixture was formed. After adding 3 parts by mass of a hydrolysis inhibitor (bis (dipropylphenyl) carbodiimide) to 100 parts by mass of the mixture, the mixture was pelletized using a twin screw extruder to prepare a so-called master batch. This master batch and polylactic acid polymer (NW4032D) were mixed at a ratio of 40% by mass to 60% by mass to prepare an aliphatic polyester resin composition. Thereafter, the aliphatic polyester resin composition was extruded from a T die at 230 ° C. using a single screw extruder, and solidified by cooling to form an unstretched film. Next, the obtained film was stretched 2.5 times in the machine direction at a temperature of 65 ° C., and then subjected to a relaxation treatment so that the longitudinal relaxation rate at the tenter outlet was 0.990. Further, in the lateral direction, the film was stretched 3.0 times at 70 ° C., and then subjected to a relaxation treatment so that the lateral relaxation rate at the tenter outlet was 0.993, and finally a film of 250 μm was obtained. About the obtained reflective film, the thermal contraction rate b after preserve | saving for 3 hours at 80 degreeC was measured about both the vertical and horizontal. Moreover, mounting evaluation was performed about the obtained reflective film. The results are shown in Table 10.

(Examples V-2 to V-26)
In Example V-1, except that the longitudinal relaxation rate and the lateral relaxation rate were changed as shown in Tables 10 to 14, in the same manner as in Example V-1, Examples V-2 to V-26 Each reflective film was produced. About the obtained reflective film, the same measurement and evaluation as Example V-1 were performed. The results are shown in Tables 10 to 14.

  As is apparent from Tables 10 to 14, the relaxation rate was set to a longitudinal relaxation rate of 0.990 to 0.996 and a lateral relaxation rate of 1.000 to 1.014 (that is, lateral relaxation was not performed or slightly stretched). In some cases, a product having a very small shrinkage after being stored at 80 ° C. for 3 hours could be obtained. Increasing the vertical relaxation rate (decreasing the value from 1) decreases the vertical contraction rate, but the expansion in the lateral direction increases from a certain point. When the lateral expansion occurred, the evaluation in the practical test decreased. Further, when relaxation was performed in the lateral direction, there was a tendency for expansion to expand in the lateral direction. Thus, it has been found that it is preferable that the transverse direction does not take relaxation or has a slight tendency to stretch.

From the above, when longitudinal relaxation and lateral relaxation are performed within the above range, the longitudinal shrinkage ratio after holding at 80 ° C. for 3 hours is larger than 0% and smaller than 0.7%, and the lateral shrinkage ratio is 0.001%. As mentioned above, it became 0.3% or less, and the best result was obtained in the evaluation in a practical evaluation test. That is, by applying moderate longitudinal relaxation and / or lateral relaxation, it is possible to realize a film having an extremely small shrinkage rate. For example, it is used for a long time as a reflective film for a large-screen liquid crystal television, etc. Even if the rise occurs, a film with little dimensional change can be provided.

  INDUSTRIAL APPLICATION This invention can be utilized for the reflective film used for reflectors etc., such as a liquid crystal display, a lighting fixture, and a lighting signboard.

Claims (6)

A process for producing an aliphatic polyester-based resin reflective film containing a polylactic acid polymer and a fine powder filler , after biaxially stretching an unstretched film, performing a relaxation treatment, and storing at 80 ° C. for 3 hours The shrinkage ratio of the film is greater than 0% and less than 0.7% in the longitudinal direction, and is −0.1% or more and 0.5% or less in the lateral direction, and the film is in the sunshine weather meter tester. The film is irradiated with ultraviolet rays for 1,000 hours, or after being irradiated with ultraviolet rays for 180 hours in a xenon weather meter tester, the average reflectance at a wavelength of 400 to 700 nm is 92% or more, and voids are formed inside the film. The manufacturing method of the aliphatic polyester-type resin reflective film characterized by having. The method for producing an aliphatic polyester-based resin reflective film according to claim 1, wherein the fine powder filler includes at least titanium oxide. The content of the fine powder filler is 10% by mass or more and 60% by mass or less in the aliphatic polyester resin composition containing the polylactic acid polymer and the fine powder filler. or method for producing aliphatic polyester resin reflective film according to 2. The method for producing an aliphatic polyester-based resin reflective film according to any one of claims 1 to 3, wherein the unstretched film is stretched at an area magnification of 5 times or more. The method for producing an aliphatic polyester-based resin reflective film according to any one of claims 1 to 4, wherein the porosity inside the film is 5% or more and 50% or less. 2. The relaxation treatment is performed such that the film has a longitudinal relaxation rate of 0.990 to 0.996 and a lateral relaxation rate of 0.993 to 1.014. The manufacturing method of the aliphatic polyester-type resin reflective film of any one of 5-5.