JPH11157037A - Microbubble-containing laminated polyester film and image receiving paper for video printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film, which is excellent in heat resistance and has a smoothness a proper flexibility, and a favorable printability when used for, for example, an image receiving paper for a video printer. SOLUTION: The microbubble-containing laminated polyester film contains at least a constitution formed by laminating a microbubble-containing polyester A layer having a density ρA of 0.50-1.20 g/cm<3> and a polyester B layer having a density ρB larger than ρA by 0.10-1.10 g/cm<3> onto each other under the condition that the thickness (t) (μm) of the B layer and its surface glossiness G(%) simultaneously satisfy the following inequalities: 17t+10<=G<=10t+90 and 40<=G<=150.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laminated polyester film containing fine bubbles and an image receiving paper for a video printer using the same.

[0002]

2. Description of the Related Art Various computers, computers, measuring instruments,
As an image receiving paper (heat-sensitive recording material) for a printer such as a copying machine and a facsimile, a paper provided with a heat-sensitive recording layer on a support such as relatively inexpensive paper is generally used. However, with the rapid diversification of printing applications, cases where higher definition is required for image quality are increasing. An image receiving paper for a video printer is one example.

When a natural paper itself is used as a support, as in a conventional image receiving paper for a video printer, the thermal recording layer is affected by the roughness of the surface of the natural paper, and a fine image cannot be obtained. In addition, similar to general photographic printing paper, image receiving paper whose surface smoothness has been improved by adhering a polyolefin film to the paper is also used, but the heat history in the image receiving paper manufacturing process and the heat applied during printing are heat resistant. There is a problem that the polyolefin film having poor properties is damaged.

When a polyester film having excellent heat resistance (containing fine bubbles, single layer) is used, there is a problem that a beautiful image is hardly obtained because the film surface does not have sufficient gloss. In order to further improve the gloss of the microbubble-containing polyester film, when a homopolymer layer of polyethylene terephthalate that does not contain microbubbles is laminated, when the thickness of the homopolymer layer is increased to obtain a constant gloss, There is a problem that the flexibility of the whole film is lost and the printing density is inferior.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an image receiving apparatus for a video printer which has excellent heat resistance, smoothness and appropriate flexibility. An object of the present invention is to provide a film having good printability when used for paper.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that a film having a specific laminated structure has excellent characteristics, and have completed the present invention. That is, the gist of the present invention, a fine-bubble-containing polyester A layer of density [rho _A is 0.50~1.20g / cm ^3, and the density [rho _B is ρ _A + 0.10g / cm ³ or more 1.10 g / a film comprising at least a structure in which a polyester B layer having a thickness of at least ³ cm ³ is laminated, wherein the thickness t (μm) of the B layer and the gloss G (%)
The present invention also provides a laminated polyester film containing fine bubbles, characterized by simultaneously satisfying the following relational expressions and the following formula, and an image-receiving paper for a video printer comprising a heat-sensitive recording layer provided on the surface of layer B of the film. .

[0007]

[Equation 2] 17t + 10 ≦ G ≦ 10t + 90 40 ≦ G ≦ 150

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polyester constituting the laminated film of the present invention is an aromatic dicarboxylic acid or an ester thereof, and a polyester obtained using glycol as a main starting material,
Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, and further include phthalic acid, adipic acid, sebacic acid, and oxycarboxylic acids (for example, p-oxyethoxybenzoic acid and the like). Alternatively, two or more kinds can be used. As the glycol component, one or more of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be used.

The polyester constituting the layer B of the laminated film of the present invention is preferably a copolymerized polyester having a copolymerization ratio of 40 mol% or less, and further comprises ethylene terephthalate or ethylene 2,6-naphthalate as a main constituent unit. It is preferable that Here, the copolymerization ratio means that, for example, when the main structural unit of the polyester is (terephthalic acid component + ethylene glycol component), the structural units other than this combination, for example, (isophthalic acid component + ethylene glycol component) are all the structural units. Means the ratio (mol%) of the number to the total.

[0010] When the structural unit of the polyester is not a single unit but a copolymer, the melting point of the polyester in the B layer is lowered, and the surface gloss can be efficiently improved in the heat treatment step at the time of film production. This is considered to be because the copolyester which is easy to soften has a higher effect of flattening the surface of the laminated film. That is, when compared under the same B layer thickness and heat treatment conditions, the increase in gloss is larger in the copolyester than in the homopolyester. Another advantage of using the copolymerized polyethylene terephthalate for the layer B is that since the flexibility of the entire laminated film is relatively maintained, the heat-sensitive recording material exhibits sufficiently high density and fine image receptivity.

When the copolymerization ratio exceeds 40 mol%,
There is a possibility that the melting point of the polyester is lowered and the polyester cannot withstand the heat history in the image receiving paper manufacturing process or the heat applied during printing. A more preferred copolymerization ratio is 1 to 20 mol%.
And 3 to 10 mol% is particularly preferred. As the copolymerization component other than the terephthalic acid or 2,6-naphthalenedicarboxylic acid component and the ethylene glycol component, isophthalic acid, diethylene glycol, triethylene glycol and the like are relatively inexpensive and have excellent characteristics and are suitable.

The melting point of the polyester constituting the layer B decreases with the copolymerization ratio. For example, when ethylene terephthalate is the main constituent unit, its melting point is usually 1
The range is 60 to 260 ° C, preferably 200 to 255 ° C, particularly preferably 230 to 250 ° C. In order for the laminated film of the present invention to exhibit fine image receptivity at a sufficiently high density as a heat-sensitive recording material, the cushioning property and the heat insulating property of the layer A containing fine bubbles also effectively function. In order to obtain such an A layer, a method in which a different kind of thermoplastic resin is blended with polyester and stretched in at least one axial direction is preferably used.

The above-mentioned different kinds of thermoplastic resins are not compatible with the polyester when kneaded and melted together with the polyester, and are dispersed in the polyester in the form of a sphere, an ellipse, a string or the like (sea-island model). Refers to a thermoplastic resin. Content An of the thermoplastic resin incompatible with polyester An
Is usually in the range of 3 to 40% by weight, preferably 5 to 30% by weight, and more preferably 10 to 20% by weight, based on the total amount with the polyester. When An is less than 3% by weight, the amount of bubbles formed in the film is reduced, and the weight tends to be inferior in terms of weight reduction and cushioning properties. On the other hand, when An exceeds 40% by weight, the mechanical strength and thermal stability of the film tend to be insufficient, and even if the layer B containing no fine bubbles is laminated, the surface of the laminated film is sufficiently smooth. May not be. In such a case, it is unsuitable for applications such as image receiving paper that require a texture and clear printability. An is 40
If the amount exceeds 10% by weight, there may be a problem in productivity that the film is likely to break during stretching.

Specific examples of thermoplastic resins incompatible with polyester include polyolefins such as polyethylene, polypropylene, polymethylpentene and polymethylbutene, as well as polystyrene, polycarbonate, polyphenylene sulfide, and liquid crystal polyester.
Among these, polypropylene, polymethylpentene, and polystyrene are preferable from the viewpoint of cost and productivity,
More preferably, it is polypropylene. In the following description, a thermoplastic resin incompatible with polyester is represented by polypropylene.

The polypropylene which can be used in the present invention is usually 95 mol% or more, and more preferably 98 mol%.
The above is preferably a crystalline polypropylene homopolymer having a propylene unit. In the case of amorphous polypropylene, polypropylene bleeds out on the surface of the unoriented polyester sheet in the film production process, and the surfaces of the cooling drum, stretching rolls, and the like are easily contaminated. Further, in the case of polypropylene in which ethylene units other than propylene units are copolymerized, for example, in an amount exceeding 5 mol%, the generation of fine bubbles tends to be insufficient.

The melt flow index (MFI) of the above polypropylene is usually 1.0 to 30 g / 10 minutes,
Preferably it is selected from the range of 2.0 to 15 g / 10 minutes. When the MFI is less than 1.0 g / 10 minutes, the generated bubbles tend to be too large, and the film may be broken at the time of stretching. The target uniformity may be degraded, and the productivity may be degraded in the production line.

In the present invention, it is preferable that a nonionic surfactant is contained (for example, kneaded) in the thermoplastic resin incompatible with the polyester. The term “surfactant” as used herein refers to a blend of different melt polymers that significantly changes the properties of the interface, that is, enhances the compatibility between the polyester and the thermoplastic resin incompatible with the polyester at the interface between the two. Refers to a compound that has an effect.
Examples of the nonionic surfactant include a polyalkylene glycol type, a polyhydric alcohol type, and a silicone type. Among them, the silicone type surfactant is preferable. More specifically, an organopolysiloxane-polyoxyalkylene copolymer, an alkenyl siloxane having a polyoxyalkylene side chain, and the like have a high surface activation effect and are preferred.

The content of the nonionic surfactant in the thermoplastic resin which is incompatible with the polyester is usually 0.1.
The range is from 01 to 10% by weight, preferably from 0.2 to 5.0% by weight. When the content of the surfactant is less than 0.01% by weight, the effect of suppressing the detachment of the thermoplastic resin from the polyester in the cast roll decreases. On the other hand, when the content of the surfactant exceeds 10% by weight, the effect of suppressing the desorption of the thermoplastic resin is no longer saturated, and conversely, adverse effects on the film quality such as lowering the whiteness of the film may occur. is there. In the present invention, the laminated film B
45 ° gloss G (%) of the layer surface (JISZ8741-
It is necessary that the method 4) of 1983 and the thickness t (μm) of the B layer simultaneously satisfy the following relational expression.

[0019]

## EQU3 ## 17t + 10≤G≤10t + 90 ... 40≤G≤150 ...

The gloss G of the surface of the layer B is (17t + 10)%
If less than or less than 40%, the density or definition of the received image is insufficient. Gloss G is (17t + 20)
% Or more and 60% or more, more preferably (17t + 30)% or more and 80% or more.

When the gloss G is more than (10t + 90)% or more than 150%, the slipperiness of the film is deteriorated, and the film surface is easily scratched. This causes problems such as the occurrence of a plurality of image receiving papers being conveyed in an overlapping manner. A more preferable range of the gloss G is (10t + 80).
% Or less and 130% or less.

The thickness t of the layer B is usually 1 to 8 μm, preferably 2 to 6 μm. If the thickness of the B layer exceeds 8 μm, the flexibility of the entire laminated film tends to be impaired.
On the other hand, if the thickness of the B layer is less than 1 μm, the gloss of the surface of the B layer tends to be insufficient. The roughness Ra of the layer B surface of the laminated film of the present invention is usually 0.03 to 0.40 μm. When this Ra is smaller than 0.03 μm, the same problem as when the glossiness exceeds the upper limit may occur. On the other hand, R
If a exceeds 0.40 μm, a problem may occur in that the received image lacks definition. The preferred range of Ra is 0.05 to 0.30 μm, and more preferably 0.07 to 0.24 μm.

The density ρ _{A of the} layer A of the laminated film of the present invention
Is 0.50 to 1.20 g / cm ³ , preferably 0.6
0 to 1.00 g / cm ³ , more preferably 0.65 to
The range is 0.90 g / cm ³ . A layer density of 1.2
If it exceeds 0 g / cm ³ , the content of bubbles is too small, and the cushioning property required for the laminated film of the present invention to exhibit excellent image receptivity is impaired. On the other hand, when the density of the layer A is less than 0.50 g / cm ³ , the mechanical strength and thermal stability of the film are insufficient, and there is an adverse effect on quality and production continuity.

Density ρ of layer B_B For ρ_A +0.1
0 g / cm^Three Above and 1.10 g / cm^Three Above
Or ρ_A +0.10 g / cm^Three More than 1.20g
/ Cm^Three Above, more preferably 1.30 g / cm^Three Less than
It is in the upper range. ρ_B Is ρ _A +0.10 g / cm^Three Less than
On and 1.10 g / cm^Three If the above is not satisfied
The glossiness of the surface layer of layer B is not sufficiently improved.

The intrinsic viscosity (IV) of the layer A polyester raw material of the laminated film of the present invention is preferably 0.55 to 0.80. If the intrinsic viscosity of the raw material is less than 0.55, the film may be easily broken at the time of film formation, or the size of the bubbles may become uneven, making it difficult to control the density. On the other hand, when the intrinsic viscosity of the raw material exceeds 0.80, the generation of fine bubbles tends to decrease.

The intrinsic viscosity (IV) of the polyester material of the layer B of the laminated film may be the same as or different from that of the layer A.
Higher values are preferred. The laminated film of the present invention is preferably white and has a high degree of concealment from the viewpoint of obtaining a beautiful image, particularly when used for various image receiving papers such as video printers. Therefore, titanium dioxide, barium sulfate, and other known white pigments may be added in order to impart whiteness and hiding properties to the film of the present invention. In order to further increase the whiteness, it is effective to add a fluorescent whitening agent.

[0027] Two or more kinds of white pigments can be contained, but in that case, it is preferable to contain at least titanium dioxide or barium sulfate. These additives can be added to only one of the layers A and B, or to both layers. The preferred content of the white pigment in each layer is
0.5 to 20% by weight, more preferably the content is 1.0 to
15% by weight.

Examples of the fluorescent whitening agent that can be preferably used include Ubitek manufactured by Ciba-Geigy, OB1 manufactured by Eastman. The preferred content of the optical brightener in each layer is in the range of 0 to 0.30% by weight. The transmission density of the laminated film of the present invention is usually 0.3 or more, preferably 0.5 or more. When the transmission density is less than 0.3, the light-shielding property of the film is insufficient, and the quality of (receiving image) as an image receiving paper may be reduced.

The whiteness of the laminated film of the present invention is J
It can be represented by a W value according to the C method of IS L1015-1992. Usually, the film W value is 70 or more, preferably 80 or more. When the W value is smaller than 70, the high-quality feeling of the (receiving image) as an image receiving paper may be impaired due to color modulation. Particles can be appropriately added to the layer B in order to impart a lubricity to the surface of the laminated film of the present invention. In particular, when the white pigment is not added to the layer B, the addition of such particles is effective. Examples of the added particles include metal oxides such as silica and alumina, salts such as calcium carbonate, and organic particles made of a crosslinked polymer. The average particle size of the added particles is usually 3 μm or less. When the average particle size exceeds 3 μm, there is a possibility that interfacial peeling may occur between the layer and the layer in contact with the layer B, problems such as detachment of particles from the film and reduction in glossiness may occur. The amount of addition
It is usually at most 7% by weight, preferably at most 0.7% by weight. If the amount exceeds 7% by weight, problems such as detachment of particles and reduction in glossiness may occur.

In the present invention, in addition to the above-mentioned white pigment, fluorescent whitening agent and lubricant in polyester and / or polypropylene, if necessary, known antioxidants, heat stabilizers, antistatic agents, Additives such as dyes, pigments, lubricants, and surfactants can be added. The film of the present invention is composed of at least two layers A and B made of different raw materials. In order to form a film, generally, a predetermined compound is melted and extruded, and then stretched in at least one axial direction according to a roll stretching method, a tenter method, or the like. In addition, in order to form fine bubbles satisfactorily and appropriately satisfy film strength and dimensional stability, it is preferable to use both a biaxial stretching method and a heat treatment method.

Here, an example in which biaxial stretching is used will be described in detail. The layer structure consists of two types and three layers of BAB and two layers of BA.
The seed layer is basically two layers, but a further multilayer structure may be used. First, the raw material of the compound for each layer is supplied to an extruder corresponding to each layer, and after melt-kneading for each extruder line, the polymer of each layer is guided to a die usually through a multi-manifold or a feed block.

Next, the molten sheet extruded from the die is rapidly cooled and solidified on a rotary cooling drum so as to have a temperature equal to or lower than the glass transition temperature, to obtain a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet and the cooling effect, it is preferable to increase the adhesion between the sheet and the rotary cooling drum, and in the present invention, the electrostatic application adhesion method is preferably employed.

Next, the obtained sheet is biaxially stretched to form a film. The fine bubbles contained in the polyester film of the present invention are usually generated by such stretching. First, usually 70 to 150 ° C., preferably 75 to 13
The unstretched sheet is stretched in one direction (longitudinal direction) under the condition of a stretching temperature of 0 ° C., usually a stretching ratio of 2.5 to 6.0 times, preferably 3.0 to 5.0 times. For such stretching, a roll and a tenter type stretching machine can be used. Then usually 75 to 150 ° C, preferably 80 to 14
Under the conditions of a stretching temperature of 0 ° C. and a stretching ratio of usually 2.5 to 6.0 times, preferably 3.0 to 5.0 times, stretching is performed in a direction (horizontal direction) orthogonal to the first stage, and biaxially. Obtain an oriented film. For such stretching, a tenter-type stretching machine can be used.

A method in which the above-described unidirectional stretching is performed in two or more stages can be adopted, but also in this case, it is preferable that the final stretching ratio falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area magnification becomes 7 to 30 times. Heat treatment is 150-2
Perform at 50 ° C. for 1 second to 5 minutes under 30% elongation, limited shrinkage or constant length. After biaxial stretching, 110 ° C ~ 18
After re-stretching at a temperature of 0 ° C. in the longitudinal direction by 1.05 to 2.0 times, heat treatment may be employed. At this time, it is also possible to appropriately adopt a technique such as heat setting before re-longitudinal stretching, longitudinal relaxation after re-longitudinal stretching, and micro-magnification longitudinal stretching before or after re-longitudinal stretching. In addition, re-stretching may be similarly performed in the lateral direction. Further, various surface treatments or the like may be performed in the film forming process as needed.

The thickness of the microbubble-containing laminated polyester film of the present invention is usually 20 to 250 μm, preferably 3 to 250 μm.
The range is from 7 to 200 μm. In addition, taking advantage of its features,
Suitable for various types of receiving paper, labels, recording paper, posters, mounts for sticker printing, lithographic printing plates, packaging materials, sticky notes, etc., including those for video printers, as a laminated film alone or as a laminated body with other materials used.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The silicone surfactant in Examples and Comparative Examples is "SH193" manufactured by Dow Silicone Toray. Various evaluation methods are as shown below. (1) Intrinsic viscosity IV of polyester (dl / g) A mixed solvent of phenol / tetrachloroethane: 50/50 (weight ratio) was added to 1 g of polyester from which other polymer components incompatible with polyester and white pigment were removed. It was added and dissolved at a ratio of 100 ml, and measured at 30 ° C.

(2) Melting point (° C.) Temperature rise rate using DSC7 type manufactured by PerkinElmer: 1
The temperature was measured at 0 ° C./min, and the temperature of the resulting peak (peak top) due to crystal melting was defined as the melting point. (3) Melt flow index MFI (g /
10 minutes) Measured according to JIS K-6758-1981. The higher this value, the lower the melt viscosity of the polymer.

(4) Average particle size (μm) of additive The centrifugal sedimentation type particle size distribution analyzer (SA-CP, manufactured by Shimadzu Corporation)
Integrated volume fraction 5 in equivalent spherical distribution measured by type 3)
The particle size of 0% was defined as the average particle size. (5) Glossiness (%) According to Method 4 (45 ° glossiness) of JIS Z-8741-1983, light was incident in the MD direction on the surface of the B layer and measured. The measurement was performed on the air surface (the side opposite to the cast roll contact surface). The average value was determined with the number of measurements taken as 3.

(6) Center line average surface roughness Ra (μm) Measured using a universal surface profiler SE-3F manufactured by Kosaka Laboratory. Measured 12 times per layer B surface under the following conditions,
The average value of 10 points excluding the upper and lower two points was taken.・ Stylus tip diameter: 2 μm ・ Measurement force: 0.03 gf ・ Measuring length: 2.5 mm ・ Cutoff value: 0.8 mm

(7) Film Density (g / cm ³ ) A 10 cm × 10 cm square sample was cut out from an arbitrary portion of the film, and its weight was measured. Next, measure the thickness of any 9 places with a micrometer, calculate the weight per unit volume from the average value and the weight,
The density value of the laminated film was used. Next, after observing the thickness of each layer of AB with a scanning electron microscope, only the layer A was cut with a microtome to obtain the density by a density gradient tube method, and at the same time, the density value of the layer B was calculated. The number of measurements was 5, and the average value was taken as the film density.

(8) Transmission Density Using a Macbeth densitometer TD-904, the transmission density by visual light was measured. The number of measurements was 5, and the average was determined. The larger the value, the lower the light transmittance. (9) Whiteness (W value) The surface of layer B was measured by a method C of JISL1015-1992 using a colorimeter 300A type (C light source, 2 ° visual field) manufactured by Nippon Denshoku Industries Co., Ltd. The number of measurements was set to 5, and the average was determined.

(10) Evaluation of image definition during printing Using a video printer (GZ-P11W manufactured by Sharp Corporation), thermal transfer recording was performed on the surface of the film B layer, and the image quality of the obtained hard copy was visually observed. From the viewpoint of the density and definition of the image, the highest quality was recognized as 3 or 3, followed by the high quality 2 or slightly lower but practicable level 1 or lower or lower. A sample lacking the definition and having a practical problem was evaluated as x.

Example 1 A polyethylene terephthalate chip having an intrinsic viscosity of 0.66, a crystalline polypropylene chip containing 0.5% by weight of a silicone-based surfactant and a crystalline polypropylene chip having an MFI of 10 g / min. 0.3 μm titanium oxide;
5% by weight and 0.05% by weight of the optical brightener OB1 were blended to prepare a uniformly blended polyester raw material A1.

Silicon dioxide having an average particle size of 1.45 μm is added to 60
A copolymerized polyethylene terephthalate raw material B1 containing 0 ppm and having an intrinsic viscosity of 0.68 and a melting point of 246 ° C. having 5 mol% of an isophthalic acid component as an acid component was produced. Each of the above-mentioned raw materials is put into a separate extruder and melted at 280 ° C., and the obtained melt is guided to the same die, and the raw material A1 is formed into an inner layer and the raw material B1 is formed into both outer layers by melt lamination. Then, the mixture was extruded into a slit shape and cooled on a cast roll at 30 ° C. to obtain two types and three layers of an unoriented sheet. Then, the film is roll-stretched 3.4 times at 80 ° C. in the flow direction (vertical direction) of the film, and further tenter-stretched at 115 ° C. in the transverse direction, and further heat-treated at 220 ° C. for 5 seconds in a tenter stretching machine. Finally, a biaxially oriented film containing fine bubbles having a thickness ratio of 4/42/4 μm was obtained. The properties of the obtained film are as shown in Table 1 below.

Example 2 A biaxially oriented film containing fine bubbles was obtained in the same manner as in Example 1 except that the final thickness ratio was changed to 2/46/2 μm. Example 3 In Example 1, the raw material B1 was replaced with an average particle size of 0.1.
It contains 6.8% by weight of 3 μm titanium dioxide and 0.05% of a fluorescent whitening agent OB1, and has an intrinsic viscosity of 0.68 and a melting point of 210.
Except for using the copolymerized polyethylene terephthalate raw material B2 at 2 ° C., the final thickness ratio was 2/46 /
A biaxially oriented film containing fine bubbles of 2 μm was obtained.

Comparative Example 1 In Example 1, the average particle size was 1.
Except for using polyethylene terephthalate raw material B3 having an intrinsic viscosity of 0.68 containing 600 ppm of 45 μm silicon dioxide and a melting point of 260 ° C., fine bubbles having a thickness ratio of 4/42/4 μm are finally contained in the same manner as in Example 1. A biaxially oriented film was obtained.

Comparative Example 2 The procedure of Example 3 was repeated, except that the raw material B2 was replaced with an average particle size of 0.1.
In the same manner as in Example 1 except that polyethylene terephthalate raw material B4 having an intrinsic viscosity of 0.68 and a melting point of 260 ° C. containing 6.8% by weight of 3 μm titanium dioxide and 0.05% by weight of fluorescent whitening agent OB1 was used. Final thickness ratio 2/46
A biaxially oriented film containing / 2 μm fine bubbles was obtained.

The results obtained are summarized in Table 1 below.

[0049]

[Table 1]

[0050]

The film of the present invention has high gloss and flexibility at the same time, is suitable for receiving paper for video printers and the like, and has very high industrial value.

Claims (4)

[Claims] 1. _A density ρ _A of 0.50 to 1.20 g / cm
³ and the density ρ _B is ρ _A
+ 0.10 g / cm ³ or more and a film with a 1.10 g / cm ³ or more polyester B layer contains at least a structure obtained by laminating, the thickness of the layer B t ([mu] m) and B
A multilayer polyester film containing fine bubbles, wherein the glossiness G (%) of the layer surface satisfies the following relational expressions at the same time. ## EQU1 ## 17t + 10 ≦ G ≦ 10t + 90 40 ≦ G ≦ 150 2. The laminated polyester film containing fine bubbles according to claim 1, wherein the layer A contains 3 to 40% by weight of a thermoplastic resin different from polyester. 3. The polyester constituting the layer B is a copolymerized polyester having a copolymerization ratio of 40 mol% or less.
Or the laminated polyester film containing fine bubbles according to 2. 4. An image receiving paper for a video printer, comprising a heat sensitive recording layer provided on the surface of the layer B of the laminated polyester film containing fine bubbles according to claim 1.