JPH11123868A - White polyester medium to be recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white polyester medium to be recorded, which is excellent in adhering property between a white polyester film and a layer to be recorded. SOLUTION: A medium to be recorded is formed of a layer to be recorded, consisting of the principal constituent of water soluble resin and formed on at least one surface of a white polyester film while being provided with the permeating density (OD) of 0.2 or more and with the (b) value of color phase of the surface of 2 or less. In this case, an easily bonded resin layer, formed by applying a resin consisting of the principal constituent of polyvinyl alcohol and coating liquid containing the principal constituting element of water soluble or water dispersing resin, is provided between the white polyester film and the layer to be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium comprising a white polyester film, and more particularly to a recording medium having improved adhesion between a recording layer and a base polyester film.

[0002]

2. Description of the Related Art In recent years, ink jet printing systems have been applied to various types of facsimile machines, printers and plotters because of low noise, high speed printing, easy full color printing, and low cost printing. The application of is rapidly progressing. On the other hand, as recording speeds and full color advance, higher quality characteristics are required for recording sheets, and various studies are being made on recording sheets. For example, in order to increase the clarity of a printed image, requirements for the hue b value and surface gloss are different from those in the related art, and there are similar requirements in a method using synthetic paper or plastic film.

[0003] A recording layer adapted to the ink jet printing system is usually formed by applying a coating solution mainly containing polyvinyl alcohol which is a water-soluble resin. However, the adhesion between the polyester film and the recording layer containing a water-soluble resin as a main component is not sufficient. Even if a conventionally known easy-adhesion resin layer is provided to improve the adhesion between the phases, sufficient adhesion cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a white polyester recording medium having excellent adhesion between a white polyester film and a recording layer. It is in.

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventor has solved the above problems easily by providing a specific adhesive resin layer between a white polyester film and a recording layer. It has been found that a white polyester film can be obtained which has been solved, and the present invention has been completed.

That is, the gist of the present invention is that the transmission density (O
A recording medium comprising a white polyester film having D) of 0.2 or more and a hue b value of less than 2 on at least one surface of which a recording layer mainly containing a water-soluble resin is formed. An easy-adhesion resin layer formed by applying a coating liquid containing a resin having polyvinyl alcohol as a main component and a water-soluble or water-dispersible resin as main components between a white polyester film and a recording layer. In a white polyester recording medium having

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, as a polyester constituting a white polyester film serving as a substrate, typically, polyethylene terephthalate (PET) in which 80 mol% or more of the structural unit is ethylene terephthalate,
Poly-2,6-naphthalate (PEN) in which at least mol% is ethylene-2,6-naphthalate, and poly-1,4 in which at least 80 mol% of the structural units are 1,4-cyclohexane dimethylene terephthalate (PCT). -Cyclohexane dimethylene terephthalate.
Other than these, polyethylene isophthalate, polybutylene terephthalate and the like can be mentioned.

[0008] Copolymerization components other than the above-mentioned superior constituents include, for example, diethylene glycol, propylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, triethylene glycol. Diol components such as polyethylene glycol, polytetramethylene glycol, polyalkylene glycol, isophthalic acid, 2,7-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid ,
Ester-forming derivatives such as sebacic acid, phthalic acid, diphenyl ether dicarboxylic acid and oxymonocarboxylic acid. The polyester used in the present invention may be a blend of a small proportion with another resin in addition to the above-mentioned homopolymer or copolymer.

In the present invention, the white polyester film to be used as the substrate is prepared by, for example, (1) a method of stretching a composition of a polyester and a white pigment, and (2) a method of stretching a composition of a polyester and a void-forming agent. Any of them can be manufactured. In the production method (1), as the white pigment, for example, titanium oxide, barium sulfate, magnesium oxide, calcium carbonate, or the like can be used. The average particle size of the white pigment is usually 0.05 to
It is 0.5 μm, preferably 0.1 to 0.4 μm.
When the average particle size is less than 0.05 μm or more than 0.5 μm, the transmission density (OD) of the film becomes small,
When used as a recording sheet, the ability to prevent light transmission tends to be insufficient. The amount of white pigment added is usually 0.5
-20% by weight, preferably 1-17% by weight. If the amount is less than 0.5% by weight, the transmission density of the film tends to be low, and the ability to prevent light transmission when formed into a recording sheet tends to be insufficient. Conversely, the amount added is 20% by weight
When the ratio exceeds the above, the film may be broken at the time of film formation, or the mechanical strength of the film may be reduced.

As the white pigment, titanium dioxide particles having a high concealing property are preferred. The crystal form of the titanium dioxide particles may be either an anatase type or a rutile type.
The anatase type is preferred from the viewpoints of value and weather resistance. The surface of the titanium dioxide particles may be treated with an oxide and / or an organic compound such as aluminum, silicon, and zinc to improve the dispersibility of the titanium dioxide particles in the polyester and the weather resistance.

In the above method (2), a polymer incompatible with polyester, for example, a polyolefin or polystyrene polymer is used as the void-forming agent. Then, according to the manufacturing method, fine bubbles are formed in the film at the time of stretching, and as a result, a low-density white polyester film is obtained. A white polyester film obtained by this method is similar to paper in terms of weight, rigidity, texture, and the like, as compared with a polyester film having the same thickness.

The type of the above-mentioned polyolefin is not particularly limited. However, when a polyolefin having a higher elastic modulus than the polyester is used in a temperature range not lower than the glass transition temperature of the polyester, many fine bubbles are generated in the polyester film. be able to. Examples of the polyolefin include polyethylene and polypropylene. The melt flow index of the polyolefin is usually 0.2 to 120, preferably 0.5 to 50.
Range.

Examples of the polystyrene-based polymer include a polystyrene homopolymer obtained by polymerizing a styrene monomer, a random copolymer with another monomer mainly composed of styrene repeating units, and a block copolymer. Or a graft copolymer. In particular,
For example, amorphous polystyrene, crystalline polystyrene, high-impact polystyrene, acrylonitrile styrene copolymer, acrylonitrile-butadiene-styrene copolymer and the like can be mentioned.

Specific examples of other incompatible polymers include, for example, poly-3-methylbutene-1, poly-4-
Methylpentene-1, polyvinyl-t-butane, 1,4
-Trans-poly-2,3-dimethylbutadiene, polyvinylcyclohexane, polyvinyl-t-butyl ether, cellulose triacetate, cellulose tripropionate, polyvinyl fluoride, polychlorotrifluoroethylene and the like. Further, polymers such as polyarylate, polyacryl, and silicone can also be used as incompatible polymers.

In the composition comprising the polyester and the incompatible polymer, the content of the polyester is from 70 to 98.
% By weight, and the content of the incompatible polymer is preferably in the range of 2 to 30% by weight. If the polyester content is less than 70% by weight, the dimensional stability of the white polyester film tends to be poor. On the other hand, when the content of the incompatible polymer exceeds 30% by weight, the generated air bubbles become too large, and the stretchability may be deteriorated, such as causing breakage during stretching. When the content of the incompatible polymer is less than 2% by weight, the amount of generated bubbles tends to be insufficient.

The apparent specific gravity of the white polyester film obtained by the production method (2) is usually 0.4 or more, preferably 0.6 or more, more preferably 0.7 or more. When the apparent specific gravity is less than 0.4, the cohesive force of the film is reduced, and the cohesive force inside the foam layer is smaller than the adhesive force at the interface between the easily adhesive resin layer and the recording layer, and the easy adhesive property is reduced. Not suitable for characteristic films.

In the present invention, the white polyester film serving as the substrate may contain, in addition to the polyester and the incompatible polymer, another polymer as a third component in an amount of not more than 20% by weight unless the gist of the present invention is exceeded. May be contained. Further, the white film obtained by the production method of the above (2) is required to have a high transmission density.
It may contain the above-mentioned white pigment similarly to the production method of the above (1). As the white pigment used in combination, titanium oxide is preferably used as a pigment that effectively improves the transmission density with a small amount, from the relationship between the addition concentration and the transmission density. Titanium oxide may be used alone as a white pigment, or may be used in combination with another white pigment.

Further, the white polyester film of the present invention comprises a fluorescent whitening agent, a stabilizer, a coloring agent, an antifoaming agent, an antistatic agent, an antioxidant, a lubricant, an antiblocking agent, an antioxidant, and an ultraviolet absorber. , A light blocking agent, a coloring agent and the like. Further, in order to improve the lubricity of the film, fine particles such as an inorganic lubricant and an organic lubricant may be contained.

The fine particles include, for example, synthetic silica, kaolin, clay, calcium carbonate, silicon oxide,
Calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, lithium fluoride, crosslinked polymer,
High melting point organic compounds that are insoluble during melt film formation of polyester are exemplified. Further, internal particles formed inside the polymer at the time of polyester production by a metal compound catalyst used at the time of polyester synthesis, for example, an alkali metal compound, an alkaline earth metal compound or the like can be mentioned. Among these, synthetic silica is preferred. The average particle size of the fine particles is usually in the range of 0.001 to 3.5 μm, and the content in the film is usually in the range of 0.002 to 0.9% by weight.

The white polyester film having a laminated structure is
A coextrusion method (co-extrusion method), a dry lamination method and the like are used, but a coextrusion method is preferable. In the coextrusion method, after each of the polyester chips constituting each layer of the laminate is dried in advance, the necessary additives are mixed and melt-kneaded using a separate extruder, and then combined in a pipe or a die. This is a method of extruding a multi-layered sheet from a die onto a casting drum (rotary cooling drum).

For drying the polyester chips, a hopper drier, a paddle drier, a vacuum drier or the like can be used. Extrusion is preferably performed by a T-die method. In casting, the use of the electrostatic contact method is encouraged. The temperature of the casting drum in the co-extrusion method is preferably set to a low temperature (about 70 ° C. or less).
The obtained unstretched sheet is stretched in the longitudinal and transverse directions, and a method of heat setting is employed. Stretching is (Tg-10)
1.degree. C. or higher and (Tg + 50) .degree.
The heat setting is preferably performed in a range of 0 to 6.0 times, and the heat setting is preferably performed in a temperature range of 150 ° C to 250 ° C.

The heat setting is generally carried out under tension fixing, but at the time of heat setting and / or cooling after heat setting, the film is relaxed or unraveled by not more than 20% in the longitudinal direction and / or the width direction of the film. Can also be performed. When the white polyester film of the present invention is used as a recording medium, the transmission density and the hue b value are in the following ranges from the impression of the color tone and appearance of the recording surface.

That is, the transmission density (OD) of the white polyester film of the present invention is 0.2 or more, preferably 0.2 to 3, particularly preferably 0.6 to 3. If the transmission density (OD) is less than 0.2, sufficient concealing properties cannot be secured as a white film, the recorded content formed on the recording layer becomes unclear, and the transmission density becomes higher than necessary. Attempting to do so would impair the mechanical strength of the film.

The hue b value of the white polyester film of the present invention is less than 2, preferably from -10 to less than 2, particularly preferably from -10 to less than 0. Hue b value is 2
Above, the film surface has a color tone including a little yellowish. When the hue b value is less than -10, the film surface has a color tone with a slight bluish tinge. The hue b value according to the present invention is:
Display method described in JIS Z-8729 (CIE197
6 colors) (L *, a *, b)
The hue b value is defined by the b * value of *).

In the present invention, a resin containing polyvinyl alcohol as a main component (hereinafter referred to as a PVOH resin) contained in a coating solution for forming an easily adhesive resin layer can be synthesized by a usual polymerization reaction. The PVOH-based resin used in the present invention is not particularly limited as long as it is water-soluble. The polymerization degree of the polyvinyl alcohol component of the present invention is not particularly limited, but is usually 100 or more, preferably,
Those having 300 to 40000 are used. Polymerization degree is 10
If it is less than 0, the water resistance of the easily adhesive resin layer tends to decrease. The saponification degree of the polyvinyl alcohol component of the present invention is not particularly limited, but is 70 mol% or more,
Preferably, a saponified polyvinyl acetate having a content of 80 mol% or more and 99.9 mol% or less is practically used. The PVOH resin of the present invention may be, for example, a copolymer with polyethylene or a polyvinyl alcohol derivative that has been subjected to a modification treatment such as acetalization or butyralization, as long as the polyvinyl alcohol component is the main component. .

In the present invention, the easy-adhesion resin layer comprises the above PV
It can be formed by applying and drying a coating solution containing an OH-based resin and a water-soluble or water-dispersible resin as main components. The above-mentioned coating solution containing a water-soluble or water-dispersible resin refers to a coating solution dissolved or dispersed in water as a main solvent. Here, examples of the water dispersion method include a resin that can be forcibly dispersed in water by a surfactant or the like and a self-dispersible resin.

The water-soluble or water-dispersible resin is preferably a self-dispersing resin having a nonionic hydrophilic component such as a polyether or a hydroxyl group, an anionic hydrophilic group, and / or a cationic hydrophilic group in a molecule. A mold resin is used. The ionic group is introduced into the resin by copolymerization or the like. Specific examples thereof include, for example, anionic groups include sulfonic acid, carboxylic acid, phosphoric acid, and lithium salts, sodium salts, potassium salts, and ammonium salts thereof. Functional groups such as salts and amine salts, and cationic groups
And a functional group comprising a halogen salt compound of a secondary amine group.

The ratio of the ionic group to the resin solid content is as follows:
Usually, it is in the range of 0.05 to 8% by weight. If the amount of the ionic group is less than 0.05% by weight, the water solubility or water dispersibility of the resin tends to be poor. Conversely, when the amount of ionic groups is 8
If the amount is more than 10% by weight, the water resistance of the easily adhesive resin layer is poor,
It tends to absorb moisture easily. As a result, the white polyester films on which the easily-adhesive resin layers are formed may adhere to each other (block).

The above-mentioned water-soluble or water-dispersible resin includes a water-soluble or water-dispersible polyester resin,
At least one resin selected from the group consisting of a polyurethane resin and an acrylic resin is suitably used. The polyester used as a water-soluble or water-dispersible resin in the present invention can be synthesized by a usual polycondensation reaction using a polyvalent carboxylic acid and a polyvalent hydroxy compound as raw materials as described below.

Examples of the polycarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid,
4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid,
Adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-
Examples include hydroxybenzoic acid, monopotassium trimellitate, and ester-forming derivatives thereof.

As the polyvalent hydroxy compound, for example,
Ethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol , P-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol,
Polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane,
Sodium dimethylolethyl sulfonate, potassium dimethylolpropionate and the like can be mentioned.

The above-mentioned polyurethane as a water-soluble or water-dispersible resin can be synthesized by a usual polymerization reaction using the following polyol, polyisocyanate, chain extender, crosslinking agent and the like as raw materials. As the polyol, for example, polyoxyethylene glycol, polyoxypropylene glycol, polyoxypropylene triol, polyethers such as polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polypropylene adipate, polyhexylene adipate, poly Examples include polyesters such as caprolactone, acrylic polyols, and castor oil.

Examples of the polyisocyanate include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate,
Examples include aromatic diisocyanates such as 1,5-naphthalenediisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, aliphatic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

Examples of the chain extender or crosslinking agent include ethylene glycol, propylene glycol, butanediol, hexanediol, diethylene glycol, trimethylolpropane, glycerin, hydrazine, ethylenediamine, diethylenetriamine,
4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, water and the like.

The above water-soluble or water-dispersible acrylic resin is, for example, an acrylic or vinyl monomer mainly containing an alkyl acrylate or an alkyl methacrylate and copolymerizable therewith and having a reactive functional group. And can be synthesized by ordinary copolymerization using as a raw material. Examples of the alkyl group of the alkyl acrylate and alkyl methacrylate include a methyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, and a cyclohexyl group. Can be

Examples of the functional group introduced into the acrylic resin by copolymerization include a carboxyl group or a salt thereof, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group, An amino group or an alkylolated amino group or a salt thereof,
Examples include a hydroxyl group and a glycidyl group, and a carboxyl group or a salt thereof, an acid anhydride group, and a glycidyl group are particularly preferable. Two or more of these groups may be contained in the acrylic resin.

Further, the above acrylic resin may be used as a copolymer component such as acrylonitrile, styrenes, butyl vinyl ether, mono or dialkyl maleate, mono or dialkyl fumarate, mono or dialkyl itaconate, and methyl vinyl ketone. , Vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, vinyl trimethoxysilane, and the like may be appropriately used in combination.

The coating solution for forming the easily adhesive resin layer of the present invention may contain polyglycerol glycidyl, if necessary. The polyglycerol polyglycidyl ether of the present invention is synthesized from, for example, polyether glycerin and epichlorohydrin, and its average molecular weight is not particularly limited, but is 1200 or less, preferably 250 to 1
000 are used. As the average molecular weight increases, the degree of water solubility decreases, and it becomes difficult to use the composition for aqueous coating. When the average molecular weight is too small, the adhesive performance of the easily adhesive resin layer is reduced. The glycidyl compound contains at least two, preferably three or more glycidyl groups in the molecule. Further, the glycidyl compound contains at least one, preferably two or more hydroxyl groups in the molecule. These functional groups may be condensed between the glycidyl group and the hydroxyl group between molecules or in the molecule by heat in the easily adhesive resin layer.

If necessary, a water-soluble or water-dispersible resin other than the above may be used in the coating solution for forming the easily adhesive resin layer of the present invention. Examples of the water-soluble or water-dispersible resin other than those described above include an epoxy resin and an amide resin. Each of these skeleton structures may have a substantially composite structure by copolymerization or the like. As a resin having a composite structure, for example, acrylic resin graft polyester, acrylic resin graft polyurethane,
Vinyl resin graft polyester, vinyl resin graft polyurethane and the like can be mentioned.

The easily adhesive resin layer may contain a component which reacts with a reactive functional group contained in the resin. As the reaction components, for example, methylolated or alkylolated urea-based, melamine-based, guanamine-based, acrylamide-based, polyamide-based compounds, polyamines, oxazoline compounds, aziridine compounds, block isocyanate compounds, silane coupling agents, Examples include a titanium coupling agent, a zirco-aluminate coupling agent, a metal chelate, an organic acid anhydride, an organic peroxide, a heat or photoreactive vinyl compound and a photosensitive resin.

The easily adhesive resin layer may contain inert particles for improving its slipperiness. Examples of the inert particles include inorganic particles such as colloidal silica, alumina, calcium carbonate, and titanium oxide, and organic particles such as polystyrene resin, polyacrylic resin, and polyvinyl resin. The average particle size (d) of the inert particles is usually (L / L) when the average film thickness of the easily adhesive resin layer is (L).
3) ≦ d ≦ (3L), and further (L / 2) ≦ d ≦ (2
It is preferable to select so as to satisfy the relationship of L).

The coating liquid used for forming the easily adhesive resin layer is prepared using water as a main medium from the viewpoint of safety and hygiene. The above-mentioned coating solution may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving film forming performance as long as water is used as a main medium. The organic solvent is preferably used in a range that dissolves in water as a main medium.

The method for forming the easily-adhesive resin layer on the surface of the white polyester film is not particularly limited, but a method of applying an easily-adhesive resin coating solution in the process of producing the polyester film is preferably employed. Specific examples include a method of applying and drying on an unstretched sheet surface, a method of applying and drying on a uniaxially stretched film surface, and a method of applying and drying on a biaxially stretched film surface. Among these, it is economical to apply a coating film on the surface of the uniaxially stretched film and then simultaneously dry-harden the coating layer in the process of heat-treating the film.

Further, as a method for forming the easily-adhesive resin layer, a method in which some of the above-mentioned coating methods are used in combination may be employed, if necessary. Specifically, there is a method in which the first layer of the easily adhesive resin is applied to the surface of the unstretched sheet and dried, then stretched in one axis direction, and then the second layer of the easily adhesive resin is applied and dried. In the present invention, it is recommended from the viewpoint of production cost that a method of applying the composition to a uniaxially stretched film, stretching the film in a dried or undried state in the direction perpendicular to the uniaxial stretching direction, and then performing a heat treatment is used.

As a method of applying a coating solution, a reverse roll coater, a gravure coater, and the like described in “Coating Method”, published by Yuji Harasaki, Maki Shoten, 1979,
A rod coater, an air doctor coater, or the like can be used. The easily adhesive resin layer may be formed on only one side of the white polyester film, or may be formed on both sides. When it is formed on only one side, a layer different from the easy-adhesion resin layer may be formed on the opposite side, if necessary, so that the recording sheet support of the present invention can have other properties. The film before application may be subjected to a chemical treatment or a discharge treatment in order to improve the applicability and adhesion of the application liquid to the film. Further, in order to further improve the surface characteristics of the recording sheet support of the present invention, a discharge treatment may be performed after forming the easily adhesive resin layer.

The dry thickness of the easily adhesive resin layer is usually 0.01 to
0.5 μm, preferably in the range of 0.02 to 0.3 μm. When the thickness of the easily-adhesive resin layer is less than 0.01 μm, the easily-adhesive property may not be sufficiently exhibited,
If it exceeds μm, mutual blocking is likely to occur. The problem of blocking is particularly noticeable when an easily adhesive resin layer is provided on both sides of the film.

The recording medium of the present invention is formed by forming a recording layer mainly composed of a water-soluble resin on an easily adhesive resin layer. Examples of the water-soluble resin used for such a recording layer include resins containing gelatin, polyacrylic acid, polyvinyl alcohol, and the like as main components, and among these, polyvinyl alcohol is preferable. The water-soluble resin of the present invention may be subjected to a modification treatment such as copolymerization with other than the water-soluble resin, acetalization or butyralization as long as the resin has a water-soluble resin component as a main component in the molecule. . When the copolymerization or modification treatment is excessively performed and the water-soluble resin component is not the main component, it becomes difficult to maintain the water retention required for a recording layer such as ink jet printing using a water-soluble resin as a recording layer. , The sharpness of the image is lost.

The recording layer of the present invention preferably further contains a crosslinking agent, an additive such as colloidal silica, and the like. In particular, containing colloidal silica or the like is effective in generating an appropriate gap in the recording layer, increasing the ink absorption rate on the surface of the recording layer immediately after printing such as inkjet printing, and the like. Works to speed up apparent drying.

The recording layer of the present invention is usually applied by a conventional method using the same applicator as described above. From the viewpoint of quickly absorbing the aqueous ink in the vertical direction and minimizing the repelling and bleeding of the aqueous ink,
For a known printing device, the thickness is preferably at least 1 to 50 μm. By setting the recording layer to a thickness of 3 to 50 μm, particularly 5 to 30 μm, it becomes possible to readily absorb water-based ink and easily obtain a clear printed matter with little bleeding. The thickness of the recording layer is 1μ
If it is less than m, it may be difficult to clearly record the ink jet printing ink without bleeding, and if it is more than 50 μm, blocking of the recording layer may occur.

The recording method for the recording layer according to the present invention is recorded by a method listed as an information recording method in CMC (1996) “Market of Printer Peripheral Materials and Chemicals”. At present, information recording systems are roughly classified into digital recording systems and analog recording systems, and more specifically, electrophotographic systems, heat-sensitive systems, inkjet systems, electrostatic electrography systems, magnetography systems, and optical recording systems are exemplified. The present invention is suitable for a recording medium using a water-soluble resin as a main component as a recording layer adapted to these methods, but is not limited thereto. A water-based ink or a water-based ink may be provided by another method. For example, the case of writing with an aqueous pen is also included.

[0051]

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 evaluation method is as shown below. In Examples and Comparative Examples, “parts” represents “parts by weight”, and “%” represents “% by weight”. (1) Transmission Density (OD) Using a Macbeth densitometer “TD-904”, the transmission density (OD) under a G filter was expressed. The greater the value of the transmitted light density (OD), the greater the degree of concealment.
The measurement was performed at three points, and the average value was used as the measured value, and the evaluation was made according to the following criteria.

[0052]

[Table 1] １．０ 1.0 or more: ◎ (excellent) 0.6 or more, less than 1.0: （(good) 0.2 Above, less than 0.6: △ (normal) Less than 0.2: × (bad) ────────────────────

(2) Hue b value color analyzer ("TC-180" manufactured by Tokyo Denshoku Co., Ltd.)
0MKII type "), and according to the method of JIS Z-8722, the surface of the layer (B) of the white laminated polyester on which the layers (A) and (B) are laminated is measured, and JIS Z-8729
The color (L *, a *, b *) of the film was determined according to the display method described in (1) (CIE 1976 lightness), and the b * value was used as the hue b value. A larger b * value on the + side indicates a stronger yellow tint. The measurement was performed at three points, and the average was taken as the measured value.
It was determined based on the following criteria. Hereinafter, “b * value” is replaced by “b
Value "is displayed.

[0054]

[Table 2] 未 満 Less than -1: ◎ (excellent) -1 or more, less than 0: ○ (good) 0 or more, less than 2: △ (normal) ) 2 or more: × (bad) ──────────────────

(3) Adhesion of the recording layer The surface of the recording layer was printed in black (12 cm × 12 c) with an ink jet printer (BJC-600J manufactured by Canon).
m) and air-dry for about 12 hours or more (23 ° C, 50
% RH). Scotch tape (Nichiban 18mm)
Width) was adhered, and the state of peeling at the time of rapid peeling was visually observed, and judged according to the following criteria.

[0056]

[Table 3] 未 満 Less than 20% peeling: ○ (good) 20% or more, less than 80% peeling: △ (normal) 80% or more Peeling: × (bad) ─────────────────────

<Easy-Adhesive Resin Layer> The following resins (A to D) were blended as shown in Table 1 below to form a coating solution, and easy-adhesive resin layers of Examples and Comparative Examples were obtained. (A) Resin containing polyvinyl alcohol as a main component Polyvinyl alcohol having a saponification degree of about 94% and an average molecular weight of 500 (B) Water-soluble or water-dispersible resin (B1) Polyester Mainly contains isophthalic acid, ethylene glycol and neopentyl glycol Polyester containing a carboxylate as a water-dispersing functional group as a component (B2) Polyurethane Polyester diol mainly composed of terephthalic acid, isophthalic acid and ethylene glycol, and isophorone diisocyanate and dimethylolpropionic acid as main components and dispersed with a carboxylate (C) polyglycerol polyglycidyl ether having an average molecular weight of about 750 (D) inert particles colloidal silica having an average particle size of 0.05 μm

[0058]

[Table 4] Table 1 {AB1, B2, CD} ─────────────────── Example 1 50 45 5 Example 2 50 45 5 Example 3 35 35 255 5 Example 4 35 35 25 5 Example 5 60 35 5 Example 6 45 45 5 5 Example 7 30 60 55 5 Example 8 20 20 55 5 Comparative Example 1 95 5 Comparative Example 2 95 5 Comparative Example 3 95 5 Comparative Example 4 95 5 Comparative Example 5 50 45 5 Comparative Example 6 50 45 5 Comparative Example 7 35 35 25 5 Comparative Example 8 60 35 5

<Recording Layer> A recording layer for inkjet printing formed by applying and drying a coating solution (8%, water / isopropanol solution) composed of a polyvinyl acetal resin (“Slek KX-1” manufactured by Sekisui Chemical Co., Ltd.). The thickness of the coating layer of the recording layer was about 8 μm. The polyvinyl acetal resin is a polyvinyl alcohol having a degree of acetalization of about 8 mol%.

Example 1 100 parts of dimethyl terephthalate and ethylene glycol 6
0 parts as a starting material, and magnesium acetate
0.09 parts of tetrahydrate was introduced into the reactor, and the reaction starting temperature was adjusted to 15
The temperature was raised to 0 ° C., and the reaction temperature was gradually increased with the removal of methanol, and the temperature was raised to 230 ° C. after 3 hours.

After 4 hours, the transesterification was substantially completed. 0.04 parts of ethyl acid phosphate and 0.04 parts of antimony trioxide were added to the reaction mixture, and 4
The polycondensation reaction was performed for 30 minutes. That is, the temperature is 23
The temperature was gradually raised from 0 ° C to 280 ° C. On the other hand, the pressure was gradually reduced from the normal pressure, and finally was 0.3 mmHg. After 4 hours and 30 minutes from the start of the reaction, the reaction was stopped, and the polymer was discharged from the reactor under nitrogen pressure. The intrinsic viscosity of the obtained polyester was 0.65.

Next, the obtained polymer was subjected to solid-state polymerization at 225 ° C. and 0.3 mmHg for 10 hours.
The intrinsic viscosity of the obtained polyester R1 was 0.81. The polyester R1 was dried and blended with various additives in a blend shown in Table 2 below using a vented twin-screw extruder to obtain polyesters R2 to R4.

[0063]

[Table 5] Table 2 ポ リ エ ス テ ル Polyester type Additive type Additive content Grain Diameter (μm) ─────────────────────────────────── R1 None R2 Titanium dioxide 40% 0.3 R3 Amorphous silica 3% 3.5 R4 Optical brightener (OB-1) ^* 1% * * OB-1: Product name (Eastman Kodak Company)

The obtained polyesters R1 to R4 were converted to R
1: R2: R3: R4 = 50: 30: 16: 4 to obtain a white polyester raw material.
After drying the white polyester raw material at 180 ° C. for 4 hours,
The resin melted by an extruder set at 285 ° C. was extruded into a sheet shape using a single-layer die.
Using a cast drum (rotary cooling drum) set at 0 ° C., quenched and solidified using the electrostatic application cooling method, and the thickness is about 370 μm.
m of substantially amorphous sheet was obtained.

The obtained amorphous sheet was stretched 3.0 times in the longitudinal direction at 83 ° C., and then a coating solution was applied on the polyester surface to form the above-mentioned easily adhesive resin layer.
At 3.1 ° C., and heat-treated at 230 ° C. for 6 seconds.
A biaxially stretched white polyester film having a thickness of about 40 μm and having a predetermined easily adhesive resin coating layer was obtained. Next, the above-described coating liquid for forming a recording layer was applied to the surface of the easily adhesive resin layer by a bar coater to obtain a recording medium for inkjet printing. The properties were evaluated, and the results are shown in Table 3 below.

Examples 2 to 8 and Comparative Examples 1 to 8 In Example 1, except that the solid content ratio of the resin constituting the easily adhesive resin layer in the coating solution was changed as shown in Table 2,
A biaxially stretched white polyester film and a recording medium for inkjet printing were obtained in the same manner as in Example 1, and the characteristics were evaluated. Table 3 shows the obtained results.

[0067]

[Table 6] Table 3 ─────────────────────────── Transmission density Recording surface Adhesion b value ──────── ─────────────────── Example 1 ◎ ◎ △ Example 2 ◎ ◎ △ Example 3 ◎ ◎ ○ Example 4 ◎ ◎ ○ Example 5 ◎ ◎ △ Implementation Example 6 ◎ ◎ ○ Example 7 ◎ ◎ ○ Example 8 ◎ ◎ △ Comparative Example 1 ◎ ◎ × Comparative Example 2 ◎ ◎ × Comparative Example 3 ◎ ◎ × Comparative Example 4 ◎ ◎ × Comparative Example 5 ◎ ◎ × Comparative Example 6 ◎ ◎ × Comparative Example 7 ◎ ◎ × Comparative Example 8 ◎ ◎ × ───────────────────────────

[0068]

According to the present invention described above, it is possible to obtain a white polyester film having a sufficient concealing property and a good hue, and to provide a recording medium having excellent image clarity by using the same. The industrial value of the present invention is high.

Claims (3)

[Claims] 1. A recording layer mainly composed of a water-soluble resin is formed on at least one surface of a white polyester film having a transmission density (OD) of 0.2 or more and a hue b value of less than 2 on the surface. A recording medium comprising a white polyester film and a recording layer, wherein a coating liquid containing polyvinyl alcohol as a main component and a water-soluble or water-dispersible resin as main components is applied. A white polyester recording medium having an easily adhesive resin layer formed by the method described above. 2. The white polyester recording medium according to claim 1, wherein the coating liquid contains polyglycerol glycidyl ether. 3. The white polyester recording medium according to claim 1, wherein the water-soluble resin contained in the recording layer is a resin containing polyvinyl alcohol as a main component.