JP2001287327A - White laminated polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white laminated polyester film excellent in concealability and whiteness, hard to generate the lowering of whiteness even if exposed to ultraviolet rays or high temperature and high humidity environment for a long time, having yellowing resistance, that is, good weatherability and suitable for use as a data recording/printing material. SOLUTION: The white laminated polyester film has whiteness (b0) and a yellowing degree (Δb) satisfying formula, -6.0<=b0<=-2.0 (1) and formula, Δb<=3.5 (2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a white laminated polyester film, in particular, excellent in concealing property and whiteness, and
The present invention relates to a white laminated polyester film having good weather resistance (yellowing resistance) and suitable as an information recording / printing material.

[0002]

2. Description of the Related Art Conventionally, a film made of a synthetic resin as a main raw material has excellent characteristics such as water resistance, moisture absorption dimensional stability, surface stability, mechanical strength, etc. compared to paper. It is attracting attention as an alternative display material, and in recent years, application development utilizing these advantages has been promoted. Synthetic resins such as polypropylene, polyester, and polystyrene are used as the main raw materials for films used as display materials. Of these, films made of polyester such as polyethylene terephthalate have high heat resistance, glossiness of printing, and sharpness. Excellent in sex, waist strength,
The range of use as printing materials and information recording materials is expanding.

[0003] When using this polyester film as a paper substitute, methods for dispersing fine voids in the film and a method for adding a white pigment have been studied as methods for imparting the necessary whiteness and hiding properties. Have been. For example, in Japanese Patent Application Laid-Open No. 9-31229, utilization of a film having whiteness and concealment property by dispersing fine cavities in a base resin as a recording material has been studied. However, in films imparted with whiteness and concealing properties by this method, mechanical properties such as strength reduction and wrinkling caused by the presence of cavities are essentially unavoidable, and the content of cavities naturally An upper limit occurs. For this reason, a film obtained by this method having sufficient whiteness and concealing property for use in the above-mentioned applications has not been obtained, and a combination with a method of adding a white pigment is actually being studied. .

As a method of adding a white pigment to a base resin of a film to impart concealing properties, for example, Japanese Patent Application Laid-Open No.
In 244188 and the like, many methods of adding fine particles of calcium carbonate, barium sulfate, and titanium dioxide have been studied. However, according to the method of adding calcium carbonate or barium sulfate, a large amount of particles must be added to exhibit sufficient hiding power because the refractive index of these pigment particles is small. As a result, this method causes problems such as an increase in cost and a decrease in film strength, and in reality, a method suitable for the above-mentioned application has not yet been obtained.
On the other hand, the method of adding titanium dioxide particles has been widely studied for its use because a high concealing property can be exhibited with a small amount by utilizing the high refractive index characteristic of the particles. However, in recent years, as the use as an information recording / printing material has expanded, the demand for synthetic paper having higher whiteness has increased, and the addition of only white pigments has become insufficient to obtain sufficient whiteness. Have been.

As a solution to this problem, a method of adding a fluorescent whitening agent in addition to a white pigment has been studied in recent years, and rutile-type or anatase-type titanium dioxide is generally used together. However, since anatase-type titanium dioxide has a strong photocatalytic action, when used as a printing material in an environment exposed to ultraviolet light for a long period of time, the fluorescent whitening agent rapidly deteriorates, and yellowing proceeds significantly. There was a problem. At present, the photocatalytic action is reduced by subjecting titanium dioxide particles to surface treatment with other inorganic particles, etc., but due to the reduction in whiteness associated with this treatment, particles with sufficient performance have been obtained. Not been. In addition, rutile titanium dioxide does not have a problem with weather resistance because of its weak photocatalytic action, but has a unique property of strongly absorbing ultraviolet light, and does not significantly inhibit the effect of the fluorescent whitening agent to obtain whiteness. There was a problem.

As described above, in the prior art, a white polyester film having sufficient whiteness and hiding properties as an information recording material and having sufficient weather resistance has not been obtained.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned disadvantages of the prior art, is excellent in concealing properties and whiteness, and hardly causes a decrease in whiteness even when exposed to ultraviolet rays, high temperature and high humidity for a long time. It is an object of the present invention to provide a white laminated polyester film having yellowing resistance, that is, good weather resistance and suitable for use as an information recording / printing material.

[0008]

In order to achieve the above object, the white laminated polyester film of the present invention has a whiteness (b ₀ ) and a yellowing degree (Δb) of the following formulas (1) and (2). Is satisfied. −6.0 ≦ b ₀ ≦ −2.0 (1) Δb ≦ 3.5 (2)

The white laminated polyester film of the present invention having the above structure is a white laminated polyester film having excellent concealing properties and whiteness and good weather resistance and suitable for use as an information recording / printing material. .

In this case, the white laminated polyester film has a base layer made of polyester, a fluorescent whitening agent formed on at least one surface thereof, and an average particle size of 0.1 to 0.1.
What is claimed is: 1. A white laminated polyester film comprising a laminate having a surface layer containing 1.0 μm anatase type titanium dioxide particles, wherein the content of a fluorescent whitening agent (f: wt%) of the surface layer and titanium dioxide The content (t: wt%) of the particles can satisfy the following expressions (3) and (4). t <f × 200 <t + 80 (3) 6 ≦ t ≦ 45 (4)

In this case, the white laminated polyester film may have a base layer made of polyester containing 1 to 50% by weight of titanium dioxide particles.

Furthermore, in this case, the white laminated polyester film may have an apparent density of 1.3 g / cm ³ or more.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the white laminated polyester film of the present invention will be described below. Polyester used in the present invention, terephthalic acid, isophthalic acid, aromatic dicarboxylic acid such as naphthalenedicarboxylic acid or an ester thereof and ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol It is a polyester produced by polycondensation with a glycol such as this. These polyesters may be prepared by directly reacting an aromatic dicarboxylic acid and a glycol, or by subjecting an alkyl ester of the aromatic dicarboxylic acid to a transesterification reaction with a glycol followed by polycondensation, or a diglycol ester of an aromatic dicarboxylic acid. Can be produced by a method such as polycondensation. Representative examples of such polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polyethylene butylene terephthalate, and polyethylene-2,6-naphthalate. This polyester may be a homopolymer or a copolymer of the third component. In any case, in the present invention, a polyester having an ethylene terephthalate unit, a butylene terephthalate unit or an ethylene-2,6-naphthalate unit of 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more is used. Is preferred.

In the present invention, the content of the anatase type titanium dioxide particles contained in the surface layer together with the fluorescent brightener must be 6 to 45% by weight based on all components constituting the surface layer. -30% by weight, preferably 12-
More preferably, it is 25% by weight. When the content of the titanium dioxide particles is less than 6% by weight, the light transmittance of the film becomes large, and a sufficient hiding effect cannot be obtained, which is not preferable. On the other hand, when the content of the anatase type titanium dioxide particles in the surface layer exceeds 45% by weight, the fluorescent whitening agent absorbs the ultraviolet light necessary for exerting its effect due to its ultraviolet absorbing effect, and the fluorescent whitening effect is markedly reduced. It is not preferable because it inhibits the whiteness.

In the present invention, the average particle size of the anatase type titanium dioxide particles in the surface layer needs to be 0.1 to 1.0 μm, and preferably 0.2 to 0.5 μm. If the average particle size of the particles is less than 0.1 μm, the light scattering ability in the visible light region is not sufficient, and the required whiteness
It is not preferable because a large amount of particles need to be added in order to exhibit the hiding property. Further, the average particle size of the particles is 1.0
If it exceeds μm, the hue of the anatase-type titanium dioxide itself appears on the film, and it is not preferable because it is colored more than whiteness due to light scattering of particles.

Further, each layer in the laminated film may contain inorganic or organic particles as needed to further improve the concealing property and the like. However, when it is added to the surface layer containing the fluorescent whitening agent, it is necessary that the effect of the present invention is not impaired. Particles that can be added include, in addition to the above-mentioned titanium dioxide, titanium dioxide of the same or different type, silica, kaolinite, talc, calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfide, organic white pigments, etc. However, there is no particular limitation.

In the white laminated polyester film of the present invention, it is preferable that the base layer made of polyester contains titanium dioxide particles so that the content relative to the components constituting the layer is 1 to 50% by weight. When the content of the titanium dioxide particles in the polyester base layer is less than 1% by weight, the concealability of the film tends to be insufficient. On the other hand, when the content exceeds 50% by weight, the mechanical strength of the film is reduced, and the film tends to be frequently broken at the time of stretching, so that the productivity is remarkably reduced. Here, the titanium dioxide contained in the base layer may be anatase type or rutile type, but the average particle size is 0.1 to
It is preferably in the range of 1.0 μm, and 0.2 to 0.1 μm.
More preferably, it is 5 μm. The titanium dioxide particles are preferably subjected to a surface treatment for suppressing the photocatalytic action, but the presence or absence of this treatment is not particularly limited in the present invention.

In the present invention, in the surface layer containing the anatase type titanium dioxide particles and the fluorescent whitening agent, the content of the anatase type titanium dioxide particles (t: weight%) and the content of the fluorescent whitening agent (f: weight) %) Is t <f × 200 <t + 8
It is preferable to satisfy the relation of 0. When the content (f) of the fluorescent whitening agent is less than the lower limit of this relational expression, the fluorescent whitening effect is poor, and the film is yellowish, and a sufficient whiteness cannot be obtained, which is not preferable. Further, when the content of the fluorescent whitening agent exceeds the upper limit of the above relational expression, discoloration when the fluorescent whitening agent is denatured under conditions of ultraviolet irradiation or high temperature and high humidity becomes remarkable, and the weather resistance of the film decreases. Is not preferred.

The thickness of each layer of the white laminated polyester film of the present invention is not particularly limited, but the thickness of the surface layer is 3 to 30 μm and the thickness of the base layer is 10 to 300 μm.
μm, the total thickness is 20 to 300 μm, and the thickness ratio between the surface layer and the base layer is about 1: 1 to 1: 5. The layer configuration is typically a surface layer / base layer or a surface layer / base layer / surface layer, but any other layer may be laminated, and the base layer is composed of two or three or more layers. May be. In this case, at least one of the base layers containing 1 to 50% by weight of titanium oxide as the preferred example described above may be applicable.

The method for producing the white laminated polyester film of the present invention is arbitrary, and is not particularly limited. For example, an unstretched laminated film is prepared by melting a mixture having the above-described composition and co-extruding the mixture into a film. And then
A general method of stretching the unstretched laminated film can be used.

The conditions for stretching and orienting the unstretched film are closely related to the physical properties of the film. In the following, the stretching and orientation conditions will be described by taking, as an example, the sequential biaxial stretching method most preferably used, particularly the vertical and horizontal sequential biaxial stretching method in which an unstretched sheet is stretched in the longitudinal direction and then in the width direction. First, in the first longitudinal stretching step, stretching is performed between two or more rolls having different peripheral speeds. As a heating means at this time, a method using a heating roll, a method using a non-contact heating method (infrared heater, electromagnetic heating, or the like) may be used, or both may be used. Next, this longitudinally uniaxially stretched film is introduced into a tenter and stretched 2.5 to 5.0 times at a temperature lower than the melting point (Tm) of the polyester by 10 ° C. or more in the width direction. Apply. The heat treatment is preferably performed in a tenter, and is preferably performed in the range of Tm-50 ° C to Tm.

The white laminated polyester film thus obtained has high hiding power by titanium dioxide and high whiteness by titanium dioxide and a fluorescent whitening agent,
It has excellent weather resistance even when exposed to ultraviolet light or high temperature and high humidity conditions.

The whiteness (b ₀ ) of the obtained white laminated polyester film must satisfy the relational expression of -6.0 ≦ b ₀ ≦ −2.0, and particularly preferably −5.0 ≦ b. ₀ ≤
-3.5 is satisfied. Here, the whiteness (b ₀ ) is a b value (a measure of yellow tint) of a film measured by a color difference meter, and a larger value indicates a stronger yellow tint. The degree of whiteness can be adjusted by the contents of the titanium dioxide particles and the fluorescent whitening agent contained in the film. Whiteness b ₀ is strong blue is less than -6.0, undesirably can not be obtained an appropriate color becomes colored bluish when subjected to printing thereon. Further, when b ₀ exceeds -2.0, the yellowish color after the yellowing has progressed by ultraviolet irradiation or use under high temperature and high humidity becomes strong, and similarly it is difficult to maintain proper color development, which is preferable. Absent.

In the white laminated polyester film of the present invention, the yellowing degree (Δb) must be 3.5 or less. Here, the yellowing degree (Δb) is a value obtained by subtracting the b value (b ₀ ) before the treatment from the b value (b ₁ ) after the film is subjected to the weather resistance acceleration treatment, and the anatase type contained in the surface layer. It can be adjusted by the content of titanium dioxide and fluorescent brightener. When Δb is more than 3.5, it is preferable because sufficient discoloration cannot be obtained, for example, discoloration can be visually identified when yellowing has progressed by ultraviolet irradiation or use under high temperature and high humidity. Absent.

The laminated white polyester film of the present invention may have a coating layer on one or both of its surfaces. Here, by providing a coating layer, the wettability and adhesion of ink, a coating agent, and the like can be improved. As the compound constituting the coating layer, a polyester-based resin is preferable.
Compounds disclosed as means for improving the adhesiveness of ordinary polyester films, such as polyurethane resins, polyester urethane resins, and acrylic resins, can be applied.

As a method of providing a coating layer, a commonly used method such as a gravure coating method, a kiss coating method, a dip method, a spray coating method, a curtain coating method, an air knife coating method, a blade coating method, a reverse roll coating method, etc. is applied. it can. As a step of applying, any method such as a method of applying before stretching the film, a method of applying after longitudinally uniaxial stretching, and a method of applying to a biaxially stretched film is possible.

[0027]

Next, examples of the present invention and comparative examples will be described. First, a measurement / evaluation method used in the present invention will be described below.

(1) Intrinsic viscosity of polyester 60% by weight of phenol and 40% by weight of tetrachloroethane
Was dissolved in a mixed solvent of (1) and the measurement was carried out at 30 ° C.

(2) Average Particle Size of Titanium Dioxide Particles The film is cut with a microtome, and the particles on the cut surface of the film are scanned with a scanning electron microscope (Hitachi / S-3).
The photograph was taken at a magnification of 1.0 × 10 ⁴ at 500).
This is traced on a tracing film to extract the contour of the particle, and the particle part is colored with black ink. Then, the trace image is converted to an image scanner (manufactured by Seiko Epson Corporation / GT).
-8000). The obtained image is a personal computer (Macintosh) and software (Adobe Photoshop ™ 2.5J and Ultimage ™ / 242.1.1)
And the average particle size was calculated.

(3) Thickness and Apparent Density Four samples of the film were cut into 5.00 cm squares to obtain samples. The four sheets were stacked, and the thickness was measured at four points using a micrometer at four significant figures, and the average value of the stacked thickness was determined. Divide this average value by 4 to round it to three significant figures, and calculate the average thickness per sheet (tμ
m). The weight (wg) of the four samples was measured using an automatic precision balance with four significant figures, and the apparent density was determined by the following equation. The apparent density was rounded to three significant figures. Apparent density (g / cm ³ ) = (w × 10 ⁴ ) / (5.00 ×
5.00 × t × 4)

(4) Whiteness Using a color difference meter (Z-1001DP) manufactured by Nippon Denshoku Co., Ltd., the color difference was measured according to the operation manual of the color difference meter. The whiteness of the film was evaluated using the b value (b ₀ ). A larger value indicates a stronger yellow tint.

(5) Concealing property Using a turbidity meter (NDH-1001DP) manufactured by Nippon Denshoku Co., Ltd.
The total light transmittance of the film was measured in accordance with the operation manual of the turbidimeter. The smaller the value, the higher the concealing property.

(6) Degree of yellowing Using an Atlas Yubcon UC-1 accelerometer manufactured by Toyo Seiki Co., Ltd., UV irradiation at 63 ° C. ± 3 ° C. for 4 hours and humidification at room temperature for 4 hours were performed for 3 cycles. Accelerated processing was performed. After the acceleration treatment, the b value (b ₁ ) was measured according to the procedure shown in (4) above. The difference (Δb) obtained by subtracting the whiteness (b ₀ ) before the processing from the b value (b ₁ ) after the acceleration processing is determined as the yellowing degree by the acceleration test. It was evaluated that the degree was small, that is, the weather resistance was high.

(Example 1) (Preparation of master pellets) As a raw material, anatase type titanium dioxide particles having an average particle diameter of 0.3 µm were added to 50% by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g obtained by an ordinary method. Fuji Titanium / TA-30
0) The mixture obtained by mixing 50% by weight was supplied to a vent-type twin-screw extruder and preliminarily kneaded. The molten resin was continuously supplied to a vent-type single-screw kneader, kneaded and extruded, and the obtained strand was cooled and cut to prepare a titanium dioxide-containing master pellet (MA).

Next, a benzoxazole-based fluorescent whitening agent (manufactured by Eastman Chemical Company / OB-) was added to 95% by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g.
1) A mixture obtained by mixing 5% by weight is supplied to a vent-type twin-screw extruder and preliminarily kneaded, and then, the molten resin is continuously supplied to a vent-type single-screw kneader to be kneaded and kneaded to obtain a fluorescent whitening agent. The containing master pellet (MB) was prepared.

(Preparation of Film Raw Material) 75% by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g and 25% by weight of the above-mentioned titanium dioxide-containing master pellet (MA) were subjected to vacuum drying at 140 ° C. for 8 hours. The pellets were mixed to obtain a film raw material (B). 76% by weight of a polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g, 20% by weight of the above-mentioned titanium dioxide-containing master pellet (MA), and 4% by weight of a fluorescent whitening agent-containing pellet (MB) dried under the same conditions. Was mixed with pellets to obtain a film raw material (F).

(Preparation of Unstretched Film) These film raw materials were supplied to different extruders and kneaded and extruded. The film raw material (B) is further kneaded by using a static mixer provided in a flow path, and then guided to a feed block, and the base layer composed of the film raw material (B) and the surface layer composed of the film raw material (F) are divided into a surface layer / base layer. / Surface layer in this order. This was co-extruded from a T-die onto a cooling roll adjusted to 25 ° C. The discharge amount of each extruder was adjusted so that the thickness ratio of each layer became 1: 8: 1, and an unstretched film having a total thickness of 620 μm was prepared.

(Preparation of Biaxially Stretched Film) The obtained unstretched film was uniformly heated to 65 ° C. using a heating roll, and two pairs of nip rolls having different peripheral speeds (low speed roll = 2)
m / min, high-speed roll = 6.8 m / min). At this time, as an auxiliary heating device for the film, an infrared heater (rated output: 20 W / cm) having a gold reflection film in the middle of the nip roll was installed at a position 1 cm from the film surface opposite to both surfaces of the film. Guide the uniaxially stretched film thus obtained to a tenter,
It is heated to 150 ° C and stretched 3.7 times in the transverse direction.
A white laminated polyester film having a thickness of about 50 μm was obtained by performing a heat treatment at 20 ° C. for 5 seconds and relaxing the film by 4% in the width direction at 200 ° C.

Example 2 In Example 1, the intrinsic viscosity of the film raw material (F) obtained by vacuum drying was 0.62 d.
L / g of 52% by weight of polyethylene terephthalate resin and the above titanium dioxide-containing master pellet (MA) 40
A white laminated polyester film was obtained in exactly the same manner as in Example 1, except that a mixture of pellets containing 8% by weight of a fluorescent whitening agent-containing pellet (MB) was used.

(Example 3) In Example 1, as a film raw material (F), a vacuum-dried intrinsic viscosity of 0.62 d was used.
L / g of 26% by weight of polyethylene terephthalate resin and the above titanium dioxide-containing master pellet (MA) 70
A white laminated polyester film was obtained in exactly the same manner as in Example 1, except that a mixture of pellets of 4% by weight and 4% by weight of fluorescent brightener-containing pellets (MB) was used.

(Example 4) In Example 1, the film was subjected to vacuum drying as the film raw material (F) and had an intrinsic viscosity of 0.62 d.
L / g of 22% by weight of polyethylene terephthalate resin and the above titanium dioxide-containing master pellet (MA) 70
A pellet mixture of 8% by weight and 8% by weight of a fluorescent whitening agent-containing pellet (MB) was used. Further, the thickness of the unstretched film was adjusted to 3100 μm to obtain a biaxially stretched film having a thickness of about 250 μm. Otherwise, a white laminated polyester film was obtained in the same manner as in Example 1.

(Comparative Example 1) In Example 1, as a film raw material (F), the intrinsic viscosity of 0.62 d after vacuum drying was applied.
L / g of 86% by weight of polyethylene terephthalate resin and the above titanium dioxide-containing master pellet (MA) 10
A white laminated polyester film was obtained in exactly the same manner as in Example 1, except that a mixture of pellets of 4% by weight and 4% by weight of fluorescent brightener-containing pellets (MB) was used.

Comparative Example 2 In Example 1, 92% by weight of the titanium dioxide-containing master pellet (MA) was used as a film raw material (F), and a fluorescent whitening agent-containing pellet (M) was added.
B) Except that a mixture of 8% by weight of pellets was used,
A white laminated polyester film was obtained in exactly the same manner as in Example 1.

(Comparative Example 3) In Example 1, as a film raw material (F), vacuum-dried intrinsic viscosity 0.62 d
L / g of 59% by weight of polyethylene terephthalate resin and the above titanium dioxide-containing master pellet (MA) 40
A white laminated polyester film was obtained in exactly the same manner as in Example 1 except that a mixture of pellets containing 1% by weight of a fluorescent whitening agent-containing pellet (MB) was used.

(Comparative Example 4) In Example 1, as a film raw material (F), an intrinsic viscosity of 0.62 d obtained by vacuum drying was used.
L / g of polyethylene terephthalate resin (14% by weight) and the above titanium dioxide-containing master pellet (MA) 70
A white laminated polyester film was obtained in exactly the same manner as in Example 1 except that a mixture of pellets containing 16% by weight of a fluorescent whitening agent-containing pellet (MB) was used.

Table 1 shows the titanium dioxide content and the fluorescent whitening agent content of the white laminated polyester film obtained by the above method, and Table 2 shows the results of measuring the physical properties.
From Tables 1 and 2, the following can be concluded.

[0047]

[Table 1]

[0048]

[Table 2]

The white laminated polyester films of Examples 1 to 4 in which the average particle diameter and the content of the titanium dioxide particles and the content of the fluorescent whitening agent were within the preferred ranges of the present invention were high in whiteness and hiding. It was a film having good balance between properties and good weather resistance (yellowing resistance). On the other hand, in Comparative Example 1 in which the content of titanium dioxide was less than the preferable range in the present invention, the total light transmittance was high, and the necessary concealing property could not be obtained. Similarly, in Comparative Example 2 in which the titanium dioxide content exceeds the preferred range in the present invention, the white b
₀ was high, and a film having sufficient whiteness was not obtained.

[0050] The fluorescent brightener content is preferably as to range higher b ₀ Comparative Example 3 less than sufficient whiteness with films could not be obtained in the present invention. Similarly, in Comparative Example 4 in which the content of the fluorescent whitening agent was more than the preferable range in the present invention, Δb was large, and a film having sufficient weather resistance could not be obtained.

[0051]

According to the white laminated polyester film of the present invention, the yellowing resistance, which is excellent in concealing property and whiteness and hardly causes a decrease in whiteness even when exposed to ultraviolet rays or high temperature and high humidity for a long time, that is, It has good weather resistance and is suitable for use as an information recording / printing material.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Yamada, inventor 2-1-1 Katata, Otsu-shi, Shiga F-term in Toyobo Co., Ltd. General Research Laboratory 4F100 AA21A AA21B AK41A AK41B AK42 BA01 BA02 CA30A DE01A DE01B EH23 EJ38 GB41 JA13 JL00 JL09 JL10 JL10A JN13A YY00 YY00A YY00B

Claims (4)

[Claims] 1. A white laminated polyester film having a whiteness (b ₀ ) and a yellowing degree (Δb) satisfying the following formulas (1) and (2). −6.0 ≦ b ₀ ≦ −2.0 (1) Δb ≦ 3.5 (2) 2. A laminate comprising a polyester base layer and a surface layer containing a fluorescent whitening agent formed on at least one surface thereof and anatase type titanium dioxide particles having an average particle size of 0.1 to 1.0 μm. A white laminated polyester film comprising a body, wherein the content of the fluorescent whitening agent (f: wt%) and the content of titanium dioxide particles (t: wt%) of the surface layer are represented by the following formulas (3) and (3). The white laminated polyester film according to claim 1, wherein (4) is satisfied. t <f × 200 <t + 80 (3) 6 ≦ t ≦ 45 (4) 3. The white laminated polyester film according to claim 1, wherein the polyester base layer contains 1 to 50% by weight of titanium dioxide particles. 4. The white laminated polyester film according to claim 1, wherein the apparent density is 1.3 g / cm ³ or more.