JPH11348213A - Easy-to-adhere white polyester film and sheet to be thermally transferred - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a film-making property and adhesiveness by providing a primer layer on at least one surface of a specific biaxially oriented polyester film, and by using a specific copolymerized polyester, acrylic resin, and fine particles in a principal component of the primer layer. SOLUTION: A film is formed of a primer layer provided on at least one surface of a biaxially oriented polyester film consisting of polyester containing an aliphatic hydrocarbon polymer of 1-3 wt.%, and 10-25 wt.% of barium sulfate particle of an average grain size of 0.1-4 μm, an appearant density of 1.31-1.45 g/cm<3> , and a porosity of 10-22%. Then, the primer layer of the film has as its principal component (A) copolymerized polyester having a glass transition temperature of 40-80 deg.C, and a dicarboxylic component having a group -SO3 M of 8-20 mol.% relative to the whole dicarboxylic component, (B) acrylic resin having a glass transition temperature of 25-70 deg.C, and (C) fine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive white polyester film and a heat-transferable sheet, and more particularly to a primer on the surface of a biaxially oriented film containing barium sulfate particles and an aliphatic hydrocarbon polymer. A heat-transferable sheet, image paper, release sheet, card, label, display plate, white plate, etc., provided with a layer, which is useful for a substrate such as a heat-transfer sheet, and is particularly useful for a heat-transferable sheet. The present invention relates to a heat transfer sheet as a material.

[0002]

2. Description of the Related Art Conventionally, a polyester film whitened by adding an inorganic pigment or another kind of polymer is
Used as a white film for substrates such as cards, labels, display boards, white boards, stamp paper, and image paper, and as a milky white film having light transmittance and light diffusion properties for use as an illuminated board, for drafting, and for labels. Used.

[0003] It is known that suitable amounts of white inorganic particles are added to polyester to obtain these white films and milky films. For example, a biaxially stretched polyester film in which barium sulfate is dispersed and contained as white inorganic particles is described in JP-B-60-30930. In this biaxially stretched polyester film, voids (voids) formed around the barium sulfate particles are present, and higher opacity is obtained, which is described as being suitable as a base for photographic paper. .

A biaxially stretched polyester film having barium sulfate particles dispersed therein is characterized by its film flexibility due to void formation and its surface property having a pearly luster. It can be expected to be applied to various hard copy film bases, release sheets, and other various applications. However, this biaxially stretched polyester film has a problem that the surface roughness and gloss are different between front and back. .

[0005] To solve this drawback, a method of adding a fatty acid metal salt to a film is described in Japanese Patent Publication No. 7-68371.

[0006] However, with the expansion of applications, particularly of heat transfer sheets, printing base materials for printers, and metal deposition, the printing suitability has been improved and the demand for maintaining mechanical strength has been further improved. There is a problem in that the adhesive strength to ink or vapor-deposited metal must be enhanced.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In addition, film formability, printability and printability with a moderate cushion,
And to provide an easily-adhesive white polyester film having excellent adhesion. A second object of the present invention is to provide a heat-transferable sheet using the easily-adhesive white polyester film as a base material.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention.
That is, the present invention has the following two configurations. 1. It is made of a polyester containing 1% by weight or more and less than 3% by weight of an aliphatic hydrocarbon-based polymer and 10-25% by weight of barium sulfate particles having an average particle size of 0.1-4 μm, and has an apparent density of 1.31-1. 45 g / cm ³ and porosity of 10
A film provided with a primer layer on at least one side of a biaxially oriented polyester film that is
The main component of the primer layer has (A) a glass transition point of 40 to
80 ° C. and a dicarboxylic acid component having the group —SO ₃ M (where M represents a metal atom, an ammonium group, a quaternary amine or a quaternary phosphonium group in the same amount as SO ₃ ) An easily-adhesive white polyester film, comprising: a copolymerized polyester occupying 8 to 20 mol% of the components; (B) an acrylic resin having a glass transition point of 25 to 70 ° C .; and (C) fine particles. 2. A heat transfer sheet comprising the above-mentioned easily adhesive white polyester film as a base material.

The polyester constituting the biaxially oriented polyester film of the present invention is polyethylene terephthalate produced by a polycondensation reaction between terephthalic acid and ethylene glycol. In addition to the above, the polyester can also be produced by a method such as transesterification of an alkyl ester of terephthalic acid and glycol followed by polycondensation, or polycondensation of a bisglycol ester of terephthalic acid. The polyester may be a homopolymer or a copolymer of a third component. In the present invention, a polyester having an ethylene terephthalate unit of 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more is preferable.

The intrinsic viscosity of the polyester in the present invention is 0.4 or more, preferably 0.5 to 1.2, more preferably 0.55 to 0.85.
When the intrinsic viscosity is less than 0.4, the mechanical strength of the film decreases.

Examples of the aliphatic hydrocarbon polymer in the present invention include polypropylene and polymethylpentene.

The polypropylene of the present invention preferably has a melt index of 0.5 to 40 g / 10 minutes, and may be a homopolymer or a copolymer. Of these, homopolymers are preferred. If the melt index is out of the above range, a desired porosity cannot be obtained or a film-forming property is deteriorated, which is not preferable.

The melt index was measured at a temperature of 230.
It is measured according to JIS K6758 under the conditions of ° C. and a load of 2.16 kgf.

[0014] Polypropylene is based on polyester,
1% by weight or more and less than 3% by weight, preferably 1.5 to 2.5%
It is mixed with the polyester to give a weight%. If the added amount of the polypropylene is less than 1% by weight, the desired void ratio cannot be obtained, the cushioning property is reduced, and the printability becomes insufficient, which is not preferable. On the other hand, if the content is 3% by weight or more, wettability and adhesiveness of the film surface are impaired, and printability is undesirably reduced.

In addition to the above-mentioned polypropylene, a polymethylpentene resin and a polyester elastomer can also be used.

The polymeterpentene (hereinafter sometimes abbreviated to PMP) in the present invention is a polymer obtained by polymerizing 80 mol% or more, preferably 90 mol% or more of 4-methyl-1-pentene. . 4-methyl-
Examples of components other than 1-pentene include ethylene, propylene, 1-butene, 3-methyl-1-butene, and the like.

Further, the melt flow rate (hereinafter sometimes abbreviated as MFR) of the PMP is 1 to 100 g /
It is preferably in the range of 10 minutes, more preferably in the range of 5 to 80 g / 10 minutes. MFR is 1g / 10
If it is less than 10 minutes, the frequency of breaking the film in the step of stretching the unstretched sheet is undesirably high. MFR is 10
If it exceeds 0 g / 10 minutes, the apparent density of the finally obtained film will be high, which is contrary to the original purpose of improving the printability of the film, and it is not preferable because the weight cannot be reduced.

The MFR is a temperature of 260 ° C. and a pressure of 5 kgf.
And according to ASTM D1238.

The amount of PMP added to the polyester is in the range of 1 to 3% by weight, preferably 1.5 to 2.5% by weight, based on the polyester. If the addition amount is less than 1% by weight, the apparent density of the finally obtained film is increased, the porosity is reduced, and the printability is unfavorably reduced. On the other hand, if the content is 3% by weight or more, the frequency of breaking of the film in the step of stretching the unstretched sheet is undesirably increased.

In the present invention, the thermoplastic polyester elastomer (hereinafter sometimes abbreviated as TPEE) is P
This has the effect of suppressing the occurrence of delamination (lamellar peeling) due to the addition of MP.

The TPEE comprises a thermoplastic polyester as a hard segment and a poly (alkylene oxide)
It is a polyetherester block copolymer obtained by copolymerizing glycol as a soft segment, and is obtained by copolymerizing a dicarboxylic acid component, a low molecular weight glycol component and a high molecular weight glycol component.

Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,
Aromatic dicarboxylic acids such as 6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, sodium 3-sulfoisophthalate, and 1,4-cyclohexanedicarboxylic acid Examples include alicyclic dicarboxylic acids such as acids, succinic acids, oxalic acids, adipic acids, sebacic acids, dodecandioic acids, aliphatic dicarboxylic acids such as dimer acids, and ester-forming derivatives thereof.

As the low molecular weight glycol component, for example,
Aliphatic diols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, An alicyclic diol such as cyclodecane dimethanol or an ester-forming derivative thereof may be used.

As the polymer glycol component, for example,
Poly (ethylene oxide) glycol having an average molecular weight of about 400 to 5000, poly (1,2- and 1,3-propylene oxide) glycol, poly (tetramethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, ethylene oxide Poly (alkylene oxide) such as copolymer with tetrahydrofuran
Glycol.

Among these, block copolymerized polyetheresters comprising a polytetramethylene terephthalate-based polyester as a hard segment and poly (tetramethylene oxide) glycol as a soft segment are preferred from the viewpoint of improving delamination resistance. The polyester portion constituting the hard segment is mainly composed of terephthalic acid or polytetramethylene terephthalate composed of an acid component obtained by combining the same with isophthalic acid and a tetramethylene glycol component.
Mol% or less) with another dicarboxylic acid component or oxycarboxylic acid component, or a polyester in which a part of the glycol component (usually 30 mol% or less) is replaced with a low molecular weight glycol component other than the tetramethylene glycol component. Is also good. Further, a part of the polyether portion constituting the soft segment may be a polyether substituted with a dioxy component other than the tetramethylene glycol component.

Such a TPEE may contain a stabilizer, an ultraviolet absorber, a thickening / branching agent, a matting agent, a coloring agent, and other various improvers, if necessary. Also TPEE
Has an intrinsic viscosity of 0.8 to 1.7, more preferably 0.1 to 0.8.
It is preferably from 9 to 1.5.

The melting point of such TPEE is 160 to 230 ° C.
And more preferably 180.
~ 220 ° C. When the melting point of TPEE is less than 160 ° C. or higher than 230 ° C., the delamination resistance of the film is not improved, which is not preferable.

In the present invention, TP in polyester is used.
The blending ratio of EE is preferably 0.1 to 2% by weight, more preferably 0.2 to 1.5% by weight based on the polyester. If the amount of TPEE is less than 0.1% by weight, the finally obtained film does not improve the delamination resistance, which is not preferable.

In the present invention, the polyester is blended with an aliphatic hydrocarbon polymer such as polypropylene or PMP and, if desired, TPEE.
For example, it is necessary to prepare a master chip containing 5 to 15% by weight with respect to the polyester and dilute it with the polyester chip before forming the film to obtain a desired blending amount. It is preferable in increasing the value. If necessary, the master chip may contain barium sulfate or another white inorganic pigment (for example, it may be kneaded and contained). Representative examples of this white inorganic pigment include barium sulfate, titanium oxide, silicon oxide, talc, calcium carbonate,
Magnesium oxide and the like. The average particle size of these white inorganic pigments is preferably from 0.1 μm to 4 μm.

The film of the present invention contains barium sulfate particles. The barium sulfate particles are not limited by the manufacturing method, and preferably include, for example, precipitated barium sulfate particles, elutriated barium sulfate particles, and the like. Such barium sulfate particles can be easily obtained from the market.

The average particle size of the barium sulfate particles is 0.1 to 4
μm, preferably 0.4 to 3 μm, more preferably 0.6 to 1.8 μm. If the average particle diameter is less than 0.1 μm, it is difficult to uniformly disperse the polyester in the polyester, which is not preferable. On the other hand, when the diameter is larger than 4 μm, the production cost is high, and the obtained coarse particles or agglomerated particles of barium sulfate increase breakage during film stretching, which is not preferable.

The barium sulfate particles preferably have a uniform particle size, in other words, have a sharp particle size distribution. For this reason, it is preferable to carry out a classification treatment at any stage before adding to the polyester. This classification treatment can be performed by any method, and examples thereof include a filtration method, a sedimentation classification method, an air classification method, and a sand grinder method.

The amount of the barium sulfate particles added to the polyester is 10 to 25% by weight, preferably 15 to 2%.
0% by weight. If the content is less than 10% by weight, the desired void ratio cannot be obtained, and not only the cushioning property is reduced but also the whiteness is insufficient, and when printed on a film, the sharpness is impaired, which is not preferable. On the other hand, if the content of barium sulfate particles in the polyester exceeds 25% by weight, breakage during film stretching increases, which is not preferable.

In the present invention, as a method of blending barium sulfate particles with the polyester, a master chip containing the barium sulfate particles in a required concentration or more, for example, 30 to 70% by weight with respect to the polyester is prepared in advance, and a film is formed. It is preferable to obtain a desired barium sulfate concentration by diluting with a polyester chip prior to increasing the dispersibility of barium sulfate. As the mixing means at this time, a known mixing means can be used. For example, it is preferable to use a melt kneading method.

A fatty acid metal salt may be added to the polyester in the present invention. The melting point of the fatty acid metal salt is preferably from 120 to 320 ° C, more preferably from 15 to 320 ° C.
0-280 ° C. If the melting point is lower than 120 ° C., there is a problem that the polyester is liable to vaporize at the time of melt extrusion, and that the fatty acid metal salt bleeds out to the film surface in the heating step during the film forming step and stains the roll surface during the film forming step. Occurs undesirably. On the other hand, those having a melting point higher than 320 ° C. are not preferable because it is difficult to uniformly disperse them in the polyester. Further, the melting point of the fatty acid metal salt is not higher than the melting point of the polyester by 50 ° C. or more.
Preferably, it is not higher.

Among the fatty acid metal salts satisfying the above melting point, alkali metal salts and alkaline earth metal salts of fatty acids having 8 or more carbon atoms are preferable. More specifically, barium stearate, lithium stearate, sodium stearate,
Magnesium stearate, calcium stearate,
Preferred examples include sodium palmitate and magnesium palmitate. Particularly preferred are barium stearate and lithium stearate.

The content of the fatty acid metal salt in the final polyester for obtaining the biaxially stretched film is preferably such that the molar ratio to the barium sulfate particles is 0.005 to 0.050. If the molar ratio is less than 0.005, substantially no effective effect of suppressing crystallization of the polyester at the time of cooling is not exhibited. On the other hand, when the molar ratio exceeds 0.050, the effect of suppressing crystallization of the polyester is substantially saturated and does not increase, and conversely, the suppressing effect tends to decrease, which is not preferable. By this crystallization suppressing effect, breakage in the stretching step can be prevented, and the difference between the front and back of the product film can be substantially eliminated.

The timing of adding the barium sulfate particles and the fatty acid metal salt is not particularly limited as long as it is before the film formation. For example, at the time of polyester production, a method of adding after the esterification reaction or transesterification reaction is completed, a method of adding after polyester production, a method of mixing the remaining additives with the polyester containing one kind of additive, and melt-kneading, And a method of melt-kneading a polyester containing the additive and a polyester containing the remaining additives. Further, the barium sulfate particles and the fatty acid metal salt may be simultaneously mixed with the polyester chip and melt-kneaded,
This method is preferable because the effect of suppressing crystallization of polyester is more remarkable than other methods.

As a method for adjusting the addition content, a master chip in which barium sulfate particles at a high concentration and a fatty acid metal salt are mixed in a predetermined ratio with polyester is obtained. A dilution method can be preferably used. If necessary, an appropriate amount of inorganic particles other than barium sulfate particles may be contained, for example, in order to improve the concealing property (light-shielding property) of the biaxially stretched film and control the surface roughness, and to control the hue of the film. , A fluorescent whitening agent, a colored pigment, a dye, and the like may be added.

In the present invention, a primer layer is provided on one side or both sides of the film. This primer layer
The main components are (A) a copolymerized polyester, (B) an acrylic resin and (C) fine particles.

The (A) copolymerized polyester has a group represented by the formula
The dicarboxylic acid component having O ₃ M (where M represents the same equivalent of a metal atom, an ammonium group, a quaternary amine or a quaternary phosphonium group as —SO ₃ ) is used in an amount of 8 to 20 with respect to the total dicarboxylic acid component. Occupies by mole%, preferably 9-16 mole%. When the content of group -SO ₃ M is in the above range, the resulting adhesive is excellent in the film of the present invention.

M in the above group —SO ₃ M is, for example,
Alkali metal atoms such as lithium, sodium and potassium, and alkaline earth metal atoms such as magnesium and calcium are preferred, and sodium and potassium are particularly preferred. Further, M is preferably an ammonium group, a tetraethylammonium group, or a tetrabutylphosphonium group.

Specific examples of the dicarboxylic acid component containing the group —SO ₃ M include compounds represented by the following formulas (1) to (5). These may be included alone or in combination of two or more in the copolymerized polyester.

[0044]

Embedded image

(A) Group Constituting Copolymerized Polyester
Examples of the dicarboxylic acid component other than the dicarboxylic acid component having SO ₃ M include terephthalic acid, phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ketone dicarboxylic acid, 4,4′-diphenyl dicarboxylic acid,
Aromatic dicarboxylic acids such as anthracene dicarboxylic acid,
Examples thereof include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid, and dimer acids. These may be used in combination of two or more. Further, in addition to the above dicarboxylic acid component, maleic acid, fumaric acid, itaconic acid and the like can be contained.

(A) Ethylene glycol, trimethylene glycol, tetramethylene glycol (1,4-butanediol), pentamethylene glycol, neopentylene glycol, hexamethylene glycol, decamethylene Alkylene glycols having 2 to 10 carbon atoms such as glycol, alicyclic diols such as cyclohexanedimethanol, dialkylene glycols such as diethylene glycol and dipropylene glycol, hydroquinone, resorcinol, 2,2-bis (4-hydroxyphenyl) propane; Polyols such as diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Sharp glycol (polyoxyalkylene glycol), other bisphenol A / alkylene oxide adduct, and the like hydroquinone / alkylene oxide adducts.

(A) The copolymerized polyester may contain a small amount of a hydroxycarboxylic acid component such as p-hydroxybenzoic acid and p- (β-hydroxyethoxy) benzoic acid in addition to the above-mentioned dicarboxylic acid component and glycol component.

Further, the copolymerized polyester (A) may contain, in addition to the above-mentioned dicarboxylic acid component, glycol component and hydroxycarboxylic acid component, a polyfunctional component in a small amount within a range in which crosslinking does not substantially occur. it can. Examples of the polyfunctional component include trimellitic acid, dimethylolpropionic acid, glycerin, and trimethylolpropane.

The number average molecular weight of (A) the copolymerized polyester is preferably from 4000 to 27000.

Further, (A) the glass transition point of the copolymerized polyester (hereinafter, the glass transition point may be abbreviated as Tg).
Is 40 to 80 ° C, preferably 45 to 75 ° C. When the Tg of the (A) copolymerized polyester is within the above range, the film of the present invention has excellent blocking properties and can maintain easy adhesion.

The above-mentioned (A) copolymerized polyester can be produced by a method known per se. For example, the group -SO
Dicarboxylic acid component containing ₃ M, can be easily obtained by other dicarboxylic acid components and glycol components perform esterification reaction, or continue the polycondensation reaction carried out transesterification as the starting material. Desired T
The copolymerized polyester having g can be easily manufactured by adjusting the quantitative ratio of each component based on the knowledge because the relationship between the acid component composition and the glycol component composition and Tg can be known in advance by preliminary experiments. be able to.

The Tg of the acrylic resin (B) constituting the primer layer is 25 to 70 ° C., preferably 40 to 66 ° C.
It is. When the Tg is in the above range, the film of the present invention is excellent in adhesiveness and maintains blocking properties and whiteness.

As the acrylic resin (B), methyl methacrylate, ethyl acrylate, butyl acrylate, acrylic acid, methacrylic acid, acrylamide, N-
Methylol acrylamide, glycidyl methacrylate, acrylonitrile, β-hydroxyethyl acrylate, polymers or copolymers of acrylic monomers such as ammonium acrylate, and further, copolymerization of the above monomers with a small proportion of vinyl monomers exemplified by styrene Coalescence can be mentioned. The acrylic resin is preferably non-crosslinked.

The acrylic resin (B) is preferably water-soluble because it is easy to prepare a primer coating solution as an aqueous coating solution.

The fine particles (C) in the present invention exhibit an effect as a lubricant, and specifically improve the blocking property of the film of the present invention. The average particle size of the fine particles is preferably 0.01 to 1 μm. And specifically,
Organic fine particles exemplified by crosslinked acrylic resin, crosslinked polystyrene resin, and crosslinked melamine resin, inorganic fine particles exemplified by silicon oxide, titanium oxide, talc, kaolin, aluminum oxide, carbon, and silicon carbide can be exemplified. .

The proportions of (A) the copolymerized polyester, (B) the acrylic resin and (C) the fine particles are, based on the total amount thereof, 25 to 80% by weight of the copolymerized polyester and 10 to 50% by weight of the acrylic resin. 5% by weight, fine particles
Preferably it is 25% by weight. By being in the above range, the film of the present invention not only has excellent adhesiveness,
Slipperiness and whiteness are maintained.

The primer layer of the film of the present invention contains, in addition to the above components, other resins, surfactants, antistatic agents, slipperiness imparting agents and ultraviolet absorbers as long as the object of the present invention is not impaired. be able to.

In the present invention, the thickness of the primer layer is 0.1.
It is preferably from 0.01 to 0.3 μm.

To provide a primer layer on a polyester film, a copolymerized polyester and an acrylic resin are dissolved or dispersed in an aqueous solvent, and an aqueous dispersion (coating liquid) in which fine particles are dispersed is applied to one or both surfaces of the film. And then drying.

The primer layer thus formed has a uniform surface and has no spots. And since it has good adhesion to printing and printing materials, including printing inks, and also has high adhesion to metals, especially aluminum, the white polyester film of the present invention is excellent as a heat transfer sheet or a printing and printing sheet for printers. Not only that, it is also excellent as a base film for a vapor deposition film.

The film of the present invention is not limited by its production method, and can be produced, for example, by a conventionally known sequential biaxial stretching method, simultaneous biaxial stretching method, inflation method or the like. Of these, the sequential biaxial stretching method is preferred.

In the sequential biaxial stretching method or the simultaneous biaxial stretching method, a polyester having a predetermined composition is melt-extruded through a die, quenched and solidified on a casting drum previously set at about 20 to 40 ° C., and an unstretched film is obtained. obtain. The unstretched film is then stretched under generally well-known conditions, but 1.5 to 4.5 times in the machine direction, 1.5 to 4.5 times in the direction perpendicular thereto, and 6 to 15 times in area magnification. It is preferable to stretch the film. The stretching temperature is preferably from 90C to 140C.

After the biaxial stretching, heat setting can be performed if necessary. The heat setting temperature is preferably from 180 to 250 ° C. The film thickness after biaxial stretching is preferably from 20 to 250 μm.

The apparent density of the film of the present invention is 1.31.
〜1.55 g / cm ³ , preferably 1.31 to 1.40 g / cm ³ . 1.31
If it is less than g / cm ³ , the mechanical strength and stretchability of the film will be insufficient, while if it is more than 1.45 g / cm ³ , the cushioning properties will be insufficient and the printability will be insufficient, which is not preferable.

The porosity of the film of the present invention is 10 to 2
2%, preferably 13 to 20%
Range. If it is less than 10%, the cushioning property is insufficient,
If the printability is insufficient, on the other hand, if it exceeds 22%, the stretchability during production is poor, and the yield due to film cutting is undesirably reduced.

The apparent density and the porosity can be obtained in a suitable range by selecting the type and the mixing ratio of the components to be mixed with the polyester and the film forming conditions.

The coating of the primer layer in the present invention may be any of an unoriented film, a uniaxially oriented film, and a biaxially oriented film. A method of forming a film is preferred. As the application method, any known method such as roll coating can be used.

The heat transfer sheet, which is another constitution of the present invention, is a sheet on which characters, images and the like are printed by a heat transfer method, such as an image receiving paper of a sublimation type heat transfer printer. The image receiving layer is provided on the primer layer of the above-mentioned easily adhesive white polyester film.

[0069]

The present invention will be described in more detail with reference to the following examples. Each characteristic value was measured by the following method.

(1) Apparent density A sample having a size of 10 cm × 10 cm was taken, the thickness of the sample was measured with a micrometer, and the volume of the sample was determined.
Next, the weight of the sample is measured, and the weight per 1 cm ³ is calculated. The measurement is performed with five samples, and the average value is defined as the apparent density.

(2) Cavity The porosity was calculated by the following formula from the calculated density calculated from the type and amount of the components mixed in the polyester and the apparent density. Cavity ratio (%) = (1−apparent density / calculated density) × 100 Calculated density: polymer density (polyester; 1.40 g /
cm ³ ), barium sulfate density (4.47 g / cm ³ ), and density calculated from the blending amount of both components.

(3) Average particle size of particles CP-50 type centrifugal particle size analyzer manufactured by Shimadzu Corporation (Cenirifugal)
The measurement was performed using a Particle Size Analyzer. The particle size corresponding to 50 mass percent was read from the integrated curve of the particles of each particle size and its abundance calculated based on the obtained centrifugal sedimentation curve, and this value was assigned to the average particle size (Book “particle size”). Measurement Techniques ", published by the Nikkan Kogyo Shimbun, 1975, pp. 242 to 247).

(4) Melting point Melting point measuring instrument (MICRO MELTIN manufactured by Yanagimoto Seisakusho)
G POINT APPARATUS).

(5) Breaking Strength Using a tensile tester (manufactured by Toyo Baldwin, Tensilon), a sample film sampled to a width of 10 mm and a length of 150 mm in a room adjusted to a temperature of 20 ° C. and a relative humidity of 50% was prepared. The film was pulled at a distance between the chucks of 100 mm and at a pulling speed of 10 mm / min, and was obtained from the stress at break of the obtained stress-strain curve. This breaking strength is 11 kg /
If the thickness is less than ² mm, the film is likely to be broken when the film is cut into a desired size, and it is not preferable because transport failure occurs in a printing machine such as a printer.

(6) Wettability 1 (Contact Angle) The contact angle was measured according to the method of ASTM D2578-1967 using a contact angle precision measuring device CA-1 manufactured by Kyowa Kagaku Co., Ltd. Pure water was dropped on the film surface (the surface not coated with the primer), and a photograph of the shape of the water droplet after one minute was taken, and the contact angle was read from the screen. The average value of n = 5 is defined as the contact angle.

(7) Wettability 2 (Coatability) An aqueous solution (water-dispersible copolymerized polyester resin, water-dispersible acrylic resin, cross-linked acrylic resin filler) having the composition shown in Examples and Comparative Examples is applied to the film after longitudinal stretching. , A 4% concentration aqueous solution containing a surfactant in a ratio of 56: 25: 10: 9)
Was applied with a roll coater, and the coated surface was visually observed and determined as follows. ：: No repelling of coating liquid ×: Repelling of coating liquid

(8) Stretchability When the unstretched sheet was stretched in the longitudinal direction and then in the transverse direction under predetermined conditions, the following judgment was made according to the breaking frequency of the film. ：: Hardly any breakage △: Broken occasionally but product is possible ×: Broken frequently, unable to produce standard size

(9) Delamination resistance 18 m is applied to the surface of the film that has not been subjected to primer coating.
Adhere a cellophane tape of m width, press a metal roll with a diameter of 20 mm over the length of 10 cm of the affixed part, make 10 reciprocations to adhere the cellophane tape tightly, and then quickly peel off the cellophane tape with the end Was. At this time, the following judgment was made based on the extent of the area where the film was peeled off from the cellophane tape. ：: Almost no peeling, or even if peeled, peeling within 2 mm or less of major axis within 5 places △: Peeled area is less than 30% of the whole ×: Peeled area is 30% or more of the whole

(10) Adhesive Strength The pigment-receiving composition having the following composition was
m (solid content) was applied with a bar coat, and after drying, the ease of peeling of the coating composition was examined by a peel test. The peel test was based on a cellophane cross cut method. <Composition of Pigment Receptive Composition> 70 parts by weight of polyester resin (Vylon 20
0: manufactured by Toyobo) 30 parts by weight of polyester resin (Byron 29)
0: manufactured by Toyobo) 5 parts by weight of amino-modified silicone (KF393:
5% by weight of epoxy-modified silicone (X22-34)
3: Shin-Etsu Chemical Co., Ltd.) Methyl ethyl ketone 350 parts by weight Toluene 350 parts by weight <Adhesion strength determination criteria> ○: No peeling Δ: Peeling number 1/100 to 5/100 ×: Peeling number 5/100 or more

(11) Suitability for Printing After the ink receiving layer was applied to the film by the method of measuring the adhesive strength, printing was performed using a VY200 printer manufactured by Hitachi, and the printed state was observed and judged. ○: Image is clear ×: Image is unclear and partially missing

(12) Intrinsic Viscosity It was dissolved in an O-chlorophenol solution and measured at 35 ° C.

(13) Melt index JIS K under the conditions of a temperature of 230 ° C. and a load of 2.16 kgf
Measured according to 6758.

(14) Melt flow rate (MFR) ASTM D1238 at a temperature of 260 ° C. and 5 kgf
It was measured according to.

[Examples 1 to 5, Comparative Examples 1 to 5] Polyethylene terephthalate having an intrinsic viscosity of 0.64 (this was
T) and each of the precipitated barium sulfate particles having an average particle size shown in Table 1 were dried at 170 ° C. for 3 hours.
The polymer was supplied to a twin-screw extruder so that the barium sulfate concentration in the polymer became 50% by weight, melt-kneaded at 280 ° C, and quenched and solidified to obtain a barium sulfate master chip.

Further, a polypropylene resin having a melt flow rate shown in Table 1 and PET were mixed and kneaded with a twin-screw extruder to obtain a polypropylene master chip. At this time, the weight ratio of the polypropylene to the polyester was 10:90.
And Similarly, PMP resin and PTEE resin and PET
Was mixed and extruded to prepare a master chip.

Then, PET and each master chip were blended so that the contents of barium sulfate, polypropylene, PMP and TPEE in the polymer were as shown in Table 1, dried at 160 ° C., and then dried at 280 ° C. And quenched and solidified on a casting drum maintained at 40 ° C. to obtain an unstretched film.

The unstretched film was stretched 2.9 times in the machine direction at 100 ° C., and terephthalic acid, isophthalic acid,
Copolymerized polyester obtained by copolymerizing Na sulfoisophthalic acid (compound of the above formula (1): occupying 13 mol% of all dicarboxylic acid components), ethylene glycol and neopentylene glycol (Tg; In Table 2, 56 parts by weight of an acrylic resin obtained by copolymerizing methyl methacrylate, ethyl acrylate, acrylic acid, methacrylamide and N-methylolacrylamide (Tg; 42 ° C., in Table 2) Is expressed as S) 25% by weight of a crosslinked acrylic resin filler (40 nm diameter), 10% by weight of an ethylene oxide-propylene oxide copolymer and 9% by weight of an aqueous liquid (coating liquid) having a concentration of 4%. Was coated on one side with a roll coater. While drying, stretch 3.0 times in the transverse direction at 120 ° C, heat set at 225 ° C, and thickness 120μ
m was obtained. Primer layer thickness is 0.05μ
m. An ink receiving layer having the following composition was bar-coated on this film to a thickness of 3 µm (solid content).

<Composition of the ink-receiving composition> 70 parts by weight of a polyester resin (Vylon 20)
0: manufactured by Toyobo) 30 parts by weight of polyester resin (Byron 29)
0: manufactured by Toyobo) 5 parts by weight of amino-modified silicone (KF393:
5% by weight of epoxy-modified silicone (X22-34)
3: Shin-Etsu Chemical Co., Ltd.) Methyl ethyl ketone 350 parts by weight Toluene 350 parts by weight Table 1 shows the properties of the obtained film.

[0089]

[Table 1]

[Examples 6 to 12] In the composition of the aqueous liquid for forming the primer layer, the types and the amounts of the copolymerized polyester and the acrylic resin were changed as shown in Table 2. 100 parts by weight except that the resin filler is 10 parts by weight and the ethylene oxide-propylene copolymer is 9 parts by weight).
A μm film was prepared. Table 2 shows the properties of the obtained film. The primer layer of the present invention has strong adhesion to the ink receiving layer.

The types of the copolymerized polyester and acrylic resin used in Examples 6 to 12 are as follows in addition to those used in Example 1. Copolymerized polyester (denoted as Q in Table 2): 2,
Copolymer of 6-naphthalenedicarboxylic acid, isophthalic acid, 5-potassium sulfoisophthalic acid (compound of the above formula (2): occupying 11 mol% of all dicarboxylic acids), ethylene glycol, bisphenol A / ethylene oxide adduct ( Tg; 55 ° C.) Acrylic resin (denoted as T in Table 2): methyl methacrylate, glycidyl methacrylate, butyl acrylate, N-methoxymethyl acrylamide, β-hydroxyethyl methacrylate copolymer (Tg; 48 ° C.)

Comparative Example 6 The procedure of Example 1 was repeated except that the primer layer was not applied.
A film of 00 μm was obtained. Table 2 shows the evaluation results of the adhesive strength. Since the requirements of the present invention were not satisfied, the adhesive strength was unsatisfactory.

[0093]

[Table 2]

[0094]

According to the present invention, there is provided a white polyester film having a surface excellent in adhesiveness to other materials, having an appropriate cushioning property, and excellent in printability and printability with stable film-forming properties. can do. The easily-adhesive white polyester film of the present invention includes, for example, image paper for a printer, a sheet to be thermally transferred, a card, a display plate, a white plate,
It can be usefully used as a base material for photographic paper, illuminated board, drafting paper, release sheet, metallized film, and adhesive tape.

Claims (5)

[Claims] 1. An aliphatic hydrocarbon-based polymer comprising 1% to less than 3% by weight of a polyester containing 10 to 25% by weight of barium sulfate particles having an average particle diameter of 0.1 to 4 μm, and an apparent density of 1%. .31~1.45g / cm ³ and a cavity ratio on at least one surface of the biaxially oriented polyester film is 10 to 22% a film provided with a primer layer, the main component of the primer layer, (a) A dicarboxylic acid having a glass transition point of 40 to 80 ° C. and having a group —SO ₃ M (where M represents a metal atom, an ammonium group, a quaternary amine or a quaternary phosphonium group in an equivalent amount to SO ₃ ); A copolyester in which the acid component accounts for 8 to 20 mol% of the total dicarboxylic acid component, and (B) a glass transition point of 2
An easily-adhesive white polyester film comprising an acrylic resin at 5 to 70 ° C. and (C) fine particles. 2. Polyester having a melting point of 120 to 320.
2. The easily-adhesive white polyester film according to claim 1, which contains a fatty acid metal salt at a temperature of 0.005 to 0.050 at a molar ratio to the barium sulfate particles. 3. The easily-adhesive white polyester film according to claim 1, wherein the aliphatic hydrocarbon polymer is polypropylene. 4. The aliphatic hydrocarbon polymer is polymethylpentene, and the polyester contains 0.1 to 2% by weight of a thermoplastic polyester elastomer.
Or the easily-adhesive white polyester film according to 2; 5. A heat-transferable sheet comprising the easily-adhesive white polyester film according to claim 1 or 2 as a base material.