JP2007015315A - Laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white laminated film which has practically sufficient reflectivity in a visible light region, can be stably manufactured, is inhibited in the deterioration (yellowing) by an ultraviolet ray, and is hardly deformed by heat. <P>SOLUTION: The laminated film comprises a layer A of a composition composed of 3 to 50 wt.% of an inert particles having an average diameter of 0.3 to 3.0 μm and 50 to 97 wt.% of a polyester from dicarboxylic acids containing 3 to 20 mol% of isophthalic acid and 80 to 97 mol% of terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component and a layer B of a composition composed of 31 to 60 wt.% of inert particles having an average diameter of 0.3 to 3.0 μm and 40 to 69 wt.% of a polyester from dicarboxylic acids containing 3 to 100 mol% of naphthalene dicarboxylic acid and 0 to 97 mol% of terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminated film, and in particular, relates to a laminated film that has a high reflectance and is excellent in light resistance and heat resistance.

  In the past, a backlight system in which light is applied from the back of the display has been adopted in liquid crystal displays. However, in recent years, the sidelight system as disclosed in JP-A-63-62104 is thin and can be illuminated uniformly. , Has come to be widely used. In this side light system, a reflector is installed on the back surface, and this reflector is required to have high light reflectivity and high diffusibility.

  Ultraviolet rays are generated from a cold cathode tube, which is a light source used as a light directly applied from the side or the back surface. Therefore, when the usage time of the liquid crystal display is prolonged, the film of the reflector is deteriorated by the ultraviolet rays, and the luminance of the screen is lowered. In recent years, there has been a strong demand for larger screens and higher brightness of liquid crystal displays, and the amount of heat emitted from light sources has increased, making it necessary to suppress film deformation due to heat.

JP 63-62104 A Japanese Patent Publication No. 8-16175 JP 2001-226501 A JP 2002-90515 A

  An object of the present invention is to solve the problems of the prior art, and has a practically sufficient visible light region reflection performance, can be stably formed, and suppresses deterioration (yellowing) due to ultraviolet rays. It is an object of the present invention to provide a white laminated film that can be suitably used as a reflector substrate for liquid crystal displays and internally illuminated signboards that is less likely to be deformed by heat.

  That is, the present invention relates to 3 to 50% by weight of inert particles having an average particle size of 0.3 to 3.0 μm, 3 to 20% by mole of isophthalic acid and 80 to 97% by mole of terephthalic acid, and ethylene glycol as a diol component. Layer A of a composition comprising 50 to 97% by weight of polyester, 31 to 60% by weight of inert particles having an average particle size of 0.3 to 3.0 μm in contact with this layer A, and 3 to 100% by mole of naphthalenedicarboxylic acid And a laminated film composed of layer B of a composition comprising 40 to 69% by weight of a polyester comprising 0 to 97 mol% of terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component.

  According to the present invention, it is possible to stably form a film with a practically sufficient visible light region reflection performance, suppress deterioration (yellowing) due to ultraviolet rays, and reduce deformation due to heat. It is possible to provide a white laminated film that can be suitably used as a reflector substrate for a lighting type electric signboard.

Hereinafter, the present invention will be described in detail.
[polyester]
The laminated film of the present invention comprises a layer A and a layer B in contact with the layer A.
Layer A comprises 3 to 50% by weight of inert particles having an average particle size of 0.3 to 3.0 μm, 3 to 20% by mole of isophthalic acid and 80 to 97% by mole of terephthalic acid, and ethylene glycol as a diol component. It is a layer of a composition comprising 50 to 97% by weight of polyester.

  In this polyester, the proportion of isophthalic acid as the dicarboxylic acid component is 3 to 20 mol%, preferably 4 to 19 mol%, more preferably 5 to 18 mol%, and particularly preferably 6 to 15 mol%. If it is less than 3 mol%, film formation may not be possible when layer A contains, for example, 31% by weight or more of inert particles, and if it exceeds 20 mol%, thermal dimensional stability is impaired, and further, film formation There are things that cannot be done.

  In this polyester, the ratio of terephthalic acid as the dicarboxylic acid component is 80 to 97 mol%. If it is less than 80 mol%, thermal dimensional stability is impaired, and film formation may not be possible. If it exceeds 97 mol%, film formation cannot be performed when layer A contains, for example, 31% by weight or more of inert particles. Sometimes.

  The polyester of layer A is preferably substantially free of antimony elements. “Substantially not contained” means that the content is 20 ppm or less, preferably 15 ppm or less, more preferably 10 ppm or less. When the antimony element is substantially contained, in the case of a white film, it looks black and streaks, which is not preferable because the film appearance is remarkably impaired.

  In order to obtain a polyester substantially free of an antimony element, the polyester is polymerized using a catalyst other than the antimony compound. As a catalyst used for polymerization of polyester, it is preferable to use any one of a manganese (Mn) compound, a titanium (Ti) compound, and a germanium (Ge) compound.

  As the titanium compound, for example, titanium tetrabutoxide and titanium acetate can be used.

  Examples of germanium compounds include amorphous germanium oxide, fine crystalline germanium oxide, a solution in which germanium oxide is dissolved in glycol in the presence of an alkali metal or alkaline earth metal or a compound thereof, and germanium oxide is dissolved in water. A solution can be used.

  On the other hand, the layer B is composed of 31 to 60% by weight of inert particles having an average particle size of 0.3 to 3.0 μm, 3 to 100% by mole of naphthalenedicarboxylic acid and 0 to 97% by mole of terephthalic acid as a dicarboxylic acid component. It is a layer of a composition comprising 40 to 69% by weight of a polyester as a diol component.

  This polyester may further contain isophthalic acid as a dicarboxylic acid component. In this case, the content of isophthalic acid is, for example, 1 to 12 mol%, more preferably 2 to 11 mol%, based on the total dicarboxylic acid component. This isophthalic acid component is inevitably mixed when used as a raw material at the end of the laminated film generated in the manufacturing process, but it is optional whether the end portion is used as a raw material. Need not be included in the polyester.

[Inert particles]
The composition of layer A contains 3 to 50% by weight, preferably 3 to 50% by weight, more preferably 10 to 49% by weight, more preferably 15 to 48% of inert particles having an average particle size of 0.3 to 3.0 μm. % By weight, particularly preferably 20 to 47% by weight. If it is less than 3% by weight, the reflectance is lowered, the slipperiness and gloss of the film are poor, yellowing due to ultraviolet rays cannot be prevented, and if it exceeds 50% by weight, the film is easily broken.

  The composition of layer B is 31 to 60% by weight, preferably 31 to 60% by weight, more preferably 34 to 58% by weight, more preferably 38 to 56% by weight, of inert particles having an average particle size of 0.3 to 3.0 μm. %, Particularly preferably 40 to 54% by weight. If it is less than 31% by weight, the reflectance is lowered, and if it exceeds 60% by weight, the film is easily broken.

The average particle diameter of the inert particles contained in the layer A and the layer B is 0.3 to 3.0 μm, preferably 0.5 to 2.5 μm, more preferably 0.7 to 2.0 μm. . When the average particle size is less than 0.3 μm, the dispersibility of the particles becomes extremely poor and the particles are aggregated, so that troubles in the production process are likely to occur, and the film has poor gloss by forming coarse protrusions on the film. There is a possibility. On the other hand, if the average particle size exceeds 3.0 μm, the surface of the film becomes rough and the gloss decreases, and it becomes difficult to control the gloss to an appropriate range.
The half-value width of the particle size distribution of the inert particles is preferably 0.3 to 3.0 μm, more preferably 0.3 to 2.5 μm.

  As the inert particles, a white pigment is preferably used from the viewpoint of obtaining high reflection performance. Examples of white pigments include titanium oxide, barium sulfate, calcium carbonate, and silicon dioxide. Barium sulfate is particularly preferably used from the viewpoint of reflectance. The barium sulfate may have a plate shape or a spherical particle shape. By using barium sulfate, better reflectance can be obtained.

  When titanium oxide is used as the inert particles, rutile titanium oxide is preferably used. It is preferable to use rutile type titanium oxide because, compared with the case of using anatase type titanium oxide, there is less yellowing after irradiating the polyester film with light for a long time, and the change in color difference can be suppressed. This rutile type titanium oxide is preferably used after being treated with a fatty acid such as stearic acid and its derivatives, etc., since the dispersibility can be improved and the glossiness of the film can be further improved.

  In addition, when using a rutile type titanium oxide, it is preferable to perform a particle size adjustment and coarse particle removal using a refinement | purification process, before adding to polyester. As industrial means of the refining process, for example, a jet mill or a ball mill can be applied as the pulverizing means, and for example, dry or wet centrifugation can be applied as the classification means. Two or more of these means may be combined and purified step by step.

As a method of incorporating the inert particles into the polyester, it is preferable to take any of the following methods.
(A) A method of adding before transesterification or esterification reaction at the time of polyester synthesis or adding before the start of polycondensation reaction.
(A) A method of adding to polyester and melt-kneading.
(C) A method of producing master pellets to which a large amount of inert particles are added in the method (a) or (b) above, and kneading these with a polyester not containing an additive to contain a predetermined amount of additive.
(D) A method of using the master pellet of (c) as it is.

In addition, when using the method added at the time of the said polyester synthesis | combination of (a), it is preferable to add to a reaction system as a slurry disperse | distributed to glycol in titanium oxide.
In particular, it is preferable to take the above method (c) or (d).

  In the present invention, it is preferable to filter the molten polymer by using a nonwoven fabric type filter having an average opening of 10 to 100 μm, preferably an average opening of 20 to 50 μm made of a stainless steel fine wire having a wire diameter of 15 μm or less as a filter during film formation. . By performing this filtration, it is possible to obtain a film with less coarse foreign matters by suppressing aggregation of particles that are generally likely to aggregate to become coarse aggregate particles.

[Additive]
You may mix | blend a fluorescent whitening agent with the laminated | multilayer film of this invention. The fluorescent whitening agent is preferably added in a range of 0.005 to 0.2% by weight, more preferably 0.01 to 0.1% by weight as a concentration with respect to the polyester composition of layer A or layer B. . If the addition amount of the fluorescent whitening agent is less than 0.01% by weight, the reflectance in the wavelength region near 350 nm is not sufficient, so the meaning of adding is poor. Since color appears, it is not preferable.

As the fluorescent brightening agent, for example, OB-1 (manufactured by Eastman), Uvitex-MD (manufactured by Ciba Geigy), or JP-Conc (manufactured by Nippon Chemical Industry Co., Ltd.) can be used.
Further, in order to further improve the performance as required, a coating agent containing an antioxidant, an ultraviolet absorber, a fluorescent brightening agent, and the like can be applied to at least one surface of the film.

[Layer structure]
The laminated film of the present invention is a laminated film comprising a layer A and a layer B in contact with the layer A.
As long as the configuration includes this configuration, another layer may be further stacked. For example, it may be a two-layer configuration of layer A / layer B, a three-layer configuration of layer A / layer B / layer A, or a four-layer configuration of layer A / layer B / layer A / layer B. It may be a structure of five layers or more including these structures.
Considering easiness and effect on film formation, the configuration of two layers consisting of layer A / layer B or three layers consisting of layer A / layer B / layer A is particularly good.

  The thickness of the layer A is preferably 3 to 30 and more preferably 4 to 28 with respect to the total thickness 100 of the layer A and the layer B. If it is less than 3, it is not preferable from the viewpoint of deterioration by ultraviolet rays, and if it exceeds 30, it is not preferable from the viewpoint of reflectance.

  In order to impart other functions to one side or both sides of the film, a laminate in which other layers are further laminated may be used. Examples of other layers herein include a transparent polyester resin layer, a metal thin film, a hard coat layer, and an ink receiving layer.

  Hereinafter, as an example of a method for producing a laminated film of the present invention, an example of a method for producing a laminated film of layer A / layer B / layer A will be described. A laminated unstretched sheet is produced by a simultaneous multilayer extrusion method using a feed block from a polymer melted from a die. That is, the polymer melt for forming layer A and the polymer melt for forming layer B are laminated using a feed block so as to be, for example, layer A / layer B / layer A, and are spread on a die and extruded. carry out. At this time, the polymer laminated by the feed block maintains the laminated form.

  The unstretched sheet extruded from the die is cooled and solidified by a casting drum to form an unstretched film. This unstretched film is heated by roll heating, infrared heating or the like, and stretched in the longitudinal direction to obtain a longitudinally stretched film. This stretching is preferably performed by utilizing the difference in peripheral speed between two or more rolls. The stretching temperature is preferably a temperature equal to or higher than the glass transition point (Tg) of the polyester, and more preferably a temperature higher by Tg to 70 ° C. The draw ratio is preferably 2.5 to 4.0 times, more preferably 2.8 to both the longitudinal direction and the direction orthogonal to the longitudinal direction (hereinafter referred to as the transverse direction), although it depends on the required characteristics of the application. 3.9 times. If the thickness is less than 2.5 times, the thickness unevenness of the film is deteriorated and a good film cannot be obtained.

  Subsequently, the film after longitudinal stretching is subjected to lateral stretching, heat setting, and thermal relaxation in order to form a biaxially oriented film. These processes are performed while the film is running. The transverse stretching process starts from a temperature higher than the glass transition point (Tg) of the polyester. And it is performed while raising the temperature to (5 to 70) ° C. higher than Tg. Although the temperature rise in the transverse stretching process may be continuous or stepwise (sequential), the temperature is usually raised sequentially. For example, the transverse stretching zone of the tenter is divided into a plurality along the film running direction, and the temperature is raised by flowing a heating medium having a predetermined temperature for each zone. The transverse stretching ratio is preferably 2.5 to 4.5 times, more preferably 2.8 to 3.9 times, although it depends on the required characteristics of this application. If it is less than 2.5 times, the thickness unevenness of the film is deteriorated and a good film cannot be obtained, and if it exceeds 4.5 times, breakage tends to occur during film formation.

  The film after transverse stretching is preferably heat treated at a constant width or a width reduction of 10% or less at a temperature (Tm-20 to 100) while holding both ends to reduce the thermal shrinkage. When the temperature is higher than this, the flatness of the film is deteriorated, and the thickness unevenness becomes large, which is not preferable. On the other hand, if the heat treatment temperature is lower than (Tm-80) ° C., the thermal shrinkage rate may increase. Also, in order to adjust the amount of thermal shrinkage in the region of (Tm-20-100) ° C. or lower during the process of returning the film temperature to room temperature after heat setting, both ends of the film being gripped are cut off, and the take-up speed in the film vertical direction Can be adjusted and relaxed in the vertical direction. As a means for relaxing, the speed of the roll group on the tenter exit side is adjusted. As the rate of relaxation, the speed of the roll group is reduced with respect to the film line speed of the tenter, preferably 0.1 to 1.5%, more preferably 0.2 to 1.2%, particularly preferably 0.3. The film is relaxed by performing a speed reduction of ˜1.0% (this value is referred to as “relaxation rate”), and the longitudinal heat shrinkage rate is adjusted by controlling the relaxation rate. Further, the width of the film in the horizontal direction can be reduced in the process until both ends are cut off, so that a desired heat shrinkage rate can be obtained.

  The laminated film of the present invention thus obtained has a heat shrinkage rate of 85 ° C. of 0.5% or less, more preferably 0.4% or less, and most preferably 0.3% or less in two orthogonal directions. can do.

  The thickness of the laminated film after biaxial stretching is preferably 25 to 250 μm, more preferably 30 to 250 μm, and particularly preferably 40 to 250 μm. If the thickness is less than 25 μm, the reflectivity is lowered, and if it exceeds 250 μm, the increase in the reflectivity cannot be expected even if the thickness is further increased.

  The thus-obtained laminated film of the present invention has a reflectance of at least one surface of 90% or more, more preferably 92% or more, particularly preferably 94% or more in terms of an average reflectance of a wavelength of 400 to 700 nm. is there. If it is less than 90%, it is not preferable because sufficient screen brightness cannot be obtained.

Hereinafter, the present invention will be described in detail by way of examples. Each characteristic value was measured by the following method.
(1) Film thickness A film sample was measured for 10-point thickness with an electric micrometer (K-402B manufactured by Anritsu), and the average value was taken as the thickness of the film.

(2) Thickness of each layer A sample was cut into a triangle, fixed in an embedded capsule, and then embedded in an epoxy resin. Then, after embedding the sample with a microtome (ULTRACUT-S) into a thin film section having a thickness of 50 nm in parallel with the microtome, the specimen was observed and photographed with a transmission electron microscope at an acceleration voltage of 100 kv. The thickness of each layer was measured and the average thickness was determined.

(3) Reflectance An integrating sphere was attached to a spectrophotometer (Shimadzu Corporation UV-3101PC), and the reflectance when the BaSO ₄ white plate was 100% was measured over 400 to 700 nm. The reflectance was read from the obtained chart at intervals of 2 nm. The average value was determined within the above range, and then judged according to the following criteria.
○: Reflectance 90% or more in the entire measurement region Δ: Average reflectance 90% or more in the measurement region and less than 90% in one part ×: Average reflectance in the entire measurement region is less than 90%

(4) Stretchability The film was stretched 2.5 to 3.4 times in the longitudinal direction and 3.4 to 3.8 times in the transverse direction to form a film, and it was observed whether the film could be stably formed. Evaluation was made according to the following criteria.
○: Stable film formation for 1 hour or more ×: Cutting occurs within 1 hour, and stable film formation is not possible

(5) Thermal shrinkage rate The film was held in an oven set at 85 ° C. for 30 minutes in an unstrained state, the distance between the gauge points before and after the heat treatment was measured, and the thermal shrinkage rate (85 ° C. thermal shrinkage rate) according to the following formula: ) Was calculated.
Thermal shrinkage% = ((L0−L) / L0) × 100
L0: Distance between gauge points before heat treatment L: Distance between gauge points after heat treatment

(6) Glass transition point (Tg), melting point (Tm)
Using a differential scanning calorimeter (TA Instruments 2100 DSC), the measurement was performed at a heating rate of 20 m / min.

(7) Deterioration by ultraviolet rays (evaluation of light resistance)
With a xenon lamp irradiation (SUNTEST CPS +), the color change before and after the panel temperature was 60 ° C. and the irradiation time was 300 hours.
Measure the initial film hue (L1 *, a1 *, b1 *) and the film hue after irradiation (L2 *, a2 *, b2 *) with a color difference meter (Nippon Denka SZS-Σ90 COLOR MEASURING SYSTEM). The color change dE * (formula 1) was evaluated as follows.
(Formula 1)
^{dE * = {(L1 * -L2} *) 2 + (a1 * -a2 *) 2 + (b1 * -b2 *) 2} 1/2
○: dE * ≦ 10
Δ: 10 <dE * ≦ 15
×: 15 <dE *

(8) Deformation due to heat (evaluation of deflection)
The film sample was cut into A4 plate, and after processing for 30 minutes in an oven heated to 80 ° C. while the four sides of the film were fixed with a metal frame, the deformation (deflection state of the film) was visually observed.
○: A bent state is not observed.
Δ: Slight deflection is observed in part.
X: There is a bent portion, and unevenness of the deflection is observed as a bulge of 5 mm or more.

[Example 1]
132 parts by weight of dimethyl terephthalate, 18 parts by weight of dimethyl isophthalate (12 mol% based on the acid component of the polyester), 96 parts by weight of ethylene glycol, 3.0 parts by weight of diethylene glycol, 0.05 part by weight of manganese acetate, 0 parts of lithium acetate .012 parts by weight were charged into a rectifying column and a flask equipped with a distillation condenser, and heated to 150 to 235 ° C. with stirring to distill methanol to conduct a transesterification reaction. After the methanol was distilled off, 0.03 part by weight of trimethyl phosphate and 0.04 part by weight of germanium dioxide were added, and the reaction product was transferred to the reactor. Subsequently, while stirring, the pressure in the reactor was gradually reduced to 0.5 mmHg and the temperature was raised to 290 ° C. to carry out a polycondensation reaction. The obtained copolymer polyester had a diethylene glycol component amount of 2.5 wt%, a germanium element amount of 50 ppm, and a lithium element amount of 5 ppm. This polyester resin was used for layer A, and the inert particles shown in Table 1 were added. In addition, a polyester resin obtained by polymerizing 23 parts by weight of dimethyl 2,6-naphthalenedicarboxylate (12 mol% as an acid component of the polyester) instead of dimethyl isophthalate as the dicarboxylic acid component described above is used for layer B. Table 1 Inert particles shown in Table 2 were added. Supply them to two extruders each heated to 280 ° C., and combine the layer A polymer and layer B polymer using a three-layer feedblock device in which layer A and layer B are A / B / A. The sheet was molded from a die while maintaining the laminated state. Further, an unstretched film obtained by cooling and solidifying the sheet with a cooling drum having a surface temperature of 25 ° C. was heated at the described temperature, stretched in the longitudinal direction (longitudinal direction), and cooled by a roll group at 25 ° C. Subsequently, the film was stretched in a direction perpendicular to the longitudinal direction (lateral direction) in an atmosphere heated to 120 ° C. while being guided to a tenter while holding both ends of the longitudinally stretched film with clips. Thereafter, heat setting was performed in the tenter at the temperature shown in Table 2, and longitudinal relaxation was performed and lateral width was placed under the conditions shown in Table 2, followed by cooling to room temperature to obtain a biaxially stretched film. Table 2 shows the physical properties of the obtained film as a reflector substrate.

[Examples 2 to 8]
Layer A polymer and layer B polymer were prepared in the same manner as in Example 1 except that the addition amount shown in Table 1 was changed to inert particles. Films were prepared and evaluated under the film forming conditions as shown in Table 2.

[Example 9]
In the production of the polymer of layer A, 0.05 part by weight of manganese acetate was changed to 0.02 part by weight of titanium acetate, and dimethyl isophthalate was changed as shown in the table to obtain a copolyester. The obtained copolyester had an intrinsic viscosity of 0.64 dl / g, a melting point of 225 ° C., a diethylene glycol component amount of 2.5 wt%, a titanium element amount of 15 ppm, and a lithium element amount of 5 ppm. In the preparation of the polymer of layer B, the polymer of layer A and the polymer of layer B prepared in Example 1 were blended and prepared so that the acid component of the polyester was 1/11 mol%. Inert particles shown in Table 1 were added to this polyester resin, and a film was prepared and evaluated as shown in Table 2.

[Examples 10 to 11]
The polymer of layer A and layer B according to Example 1 except that dimethyl isophthalate was changed to 6 mol% as shown in Table 1 as layer A and dimethyl naphthalenedicarboxylate was changed to 100 mol% as the acid component of the polyester as layer B. Was made. Films were prepared and evaluated as shown in Table 2.

[Comparative Example 1]
After transesterification according to a conventional method using 85 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as a catalyst using 0.09 part by weight of calcium acetate, 0.18% by weight as a phosphorus compound with respect to the polymer is obtained. An ethylene glycol solution containing 10% by weight of trimethyl phosphate was added, and then 0.03 part by weight of antimony trioxide was added as a polymerization catalyst. Thereafter, a polycondensation reaction was performed according to a conventional method under high temperature and reduced pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.60. This polyester had an intrinsic viscosity of 0.65 dl / g, a melting point of 257 ° C., a diethylene glycol component amount of 1.2 wt%, an antimony element amount of 30 ppm, and a calcium element amount of 10 ppm. Inert particles shown in Table 1 were added to this resin to form layers A and B. It produced and evaluated on the conditions described in Table 2. It was easy to bend with respect to heat and deteriorated due to ultraviolet rays.

[Comparative Example 2]
Films were formed and evaluated under the conditions shown in Tables 1 and 2. It was easy to bend with respect to heat and deteriorated due to ultraviolet rays.

[Comparative Example 3]
The polymer of layer B was prepared by changing dimethyl terephthalate described in Comparative Example 1 to dimethyl naphthalate. The polymer of layer A was prepared as described in Comparative Example 1 and the other processes were carried out as shown in Tables 1 and 2, but the film was not able to be produced because of poor stretchability.

[Comparative Example 4]
The polymer obtained in Comparative Example 3 was used for both layer A and layer B and carried out as described in Tables 1 and 2. However, the film was not able to be produced because of poor stretchability.

[Comparative Example 5]
Using only the polymer obtained in layer B of Example 1 and carrying out with a single layer as described in Tables 1 and 2, the film was not able to be produced due to poor stretchability.

[Comparative Examples 6 and 7]
Except for changing 0.04 parts by weight of germanium dioxide to 0.04 parts by weight of antimony trioxide, an isophthalic acid copolymer and a 2,6-naphthalenedicarboxylic acid copolymer were obtained in the same manner as in Example 1, and each of layers A, A copolyester resin used for layer B was obtained. The amount of antimony element at this time was 40 ppm. This resin was used as shown in Tables 1 and 2. Deflection due to heat or deterioration due to ultraviolet rays was large.

[Comparative Example 8]
Using the resin of Comparative Example 1, 14% by weight of calcium carbonate was added as inorganic fine particles as the surface layers (front and back surfaces) of the three-layer film, and polymethylpentene resin, which is an incompatible resin with polyethylene terephthalate, was used as the core layer resin. A film was prepared by mixing 10% by weight and 1% by weight of polyethylene glycol. The streaks were conspicuous, and reflectivity, deflection, and deterioration due to ultraviolet rays were large.
The evaluation results are summarized in Tables 1 and 2.

  The laminated film of the present invention has a high light reflectivity, and can be optimally used for various reflectors, particularly a reflector for liquid crystal displays and a back sheet for solar cells. When using as these reflecting plates, it is preferable to use the layer A as a reflecting surface.

  Other uses include paper substitution, ie cards, labels, stickers, home delivery slips, video printer paper, inkjets, barcode printer paper, posters, maps, dust-free paper, display boards, white boards, thermal transfer, offset It can be used as a base material for receiving sheets used for various printing records such as printing, telephone cards and IC cards.

Claims (3)

  3 to 50% by weight of inert particles having an average particle size of 0.3 to 3.0 μm, polyester 50 to 30 containing isophthalic acid 3 to 20 mol% and terephthalic acid 80 to 97 mol% as a dicarboxylic acid component and ethylene glycol as a diol component 97% by weight of the composition A, 31-60% by weight of inert particles having an average particle size of 0.3-3.0 μm, 3-100 mol% of naphthalenedicarboxylic acid and 0-terephthalic acid 0 A laminated film comprising a layer B of a composition comprising 40 to 69% by weight of a polyester comprising 97 mol% of a dicarboxylic acid component and ethylene glycol as a diol component.   The laminated film according to claim 1, wherein the thickness of the layer A is 3 to 30 with respect to the total thickness 100 of the layer A and the layer B.   The laminated film according to claim 1 or 2, which is used as a reflector.