JP2001064598A - Laminated film for supporting heat-sensitive color- developing layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film for supporting a heat-sensitive color- developing layer, the film being useful as films for medical diagnosis. SOLUTION: The laminated film is formed by laminating a coating film on at least one side of a polyester film, the coating film being an electrostatic coating film obtained by coating the polyester film with a water-based coating solution comprising (A) 40-85 wt.% of a binder resin, (B) 5-50 wt.% of an antistatic agent composed primarily of a repeating unit having a structure represented by the formula, (C) 5-20 wt.% of a water-soluble polymer, and (D) 5-15 wt.% of a surface active agent, followed by drying and stretching. (In the formula, R1 and R2 are each H or CH3, R3 is a 4-10C alkylene group, R4 and R5 are each a 1-5C saturated hydrocarbon group, R6 is a 2-5C alkylene group, (m) is 1-20, (n) is 1-40, and Y is a halogen ion or the like).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film for a heat-sensitive color-forming layer support, and more particularly, to adhesion to a heat-sensitive color-forming layer, leuco dye coloring, antistatic properties, backside transferability, abrasion resistance, and blocking resistance. The present invention relates to a laminated film for a heat-sensitive coloring layer support, which has excellent properties and printability.

[0002]

2. Description of the Related Art As an image output medium for medical diagnosis, image formation using a silver salt has become widespread. In recent years, a thermosensitive coloring layer has been used as an output medium for digital signals because of the reduction in waste of a developing solution and the simplicity of processing. The spread of the media is increasing.

On the other hand, as a plastic film serving as a base material, a polyester film excellent in water resistance, chemical resistance, mechanical strength, dimensional stability, and electrical properties, particularly a film made of polyethylene terephthalate or polyethylene naphthalate is used. Has been or is being considered,
Such a polyester film has a disadvantage that it is easily charged. When the film is charged, dirt and dust adhere to the surface, causing quality problems. Further, when an organic solvent is used in the film processing step, there is a danger of ignition due to discharge from the charged film.

As a countermeasure against such a problem due to charging,
A method of kneading an anionic compound such as an organic sulfonic acid salt group, a metal powder, a carbon powder or the like into a polyester film,
A method of evaporating a metal compound on the surface of a polyester film has been proposed and put to practical use. However, such a method has a problem that the transparency of the film is reduced and a problem that processing cost is high.

As another method, various methods for forming an antistatic coating film on the film surface have been proposed and put into practical use. As the antistatic agent to be contained in the antistatic coating film, a low molecular weight type or a high molecular type is known, but each has advantages and disadvantages. Therefore, the antistatic agent can be properly used according to its characteristics.

For example, low molecular weight antistatic agents include:
Long-chain alkyl compounds having a sulfonic acid salt group
Surfactant-type anionic antistatic agents such as JP-A-28728) are known, and as a high-molecular-weight antistatic agent, a polymer having an ionized nitrogen element in the main chain (Japanese Patent Laid-Open No. Japanese Patent Application Laid-Open No. 3-255139,
288127, JP-A-6-320390)
Or sulfonic acid salt group-modified polystyrene (JP-A-5-32
No. 0394) is known.

However, in an antistatic coating film using a low molecular weight antistatic agent, a part of the antistatic agent moves in the coating film, accumulates at the interface, and moves to the opposite surface of the film ( There is a problem that the antistatic property (antistatic property) decreases with time.

On the other hand, in the case of an antistatic coating film using a polymer type antistatic agent, a large amount of an antistatic agent is required to obtain good antistatic properties, It is not economical because it is necessary to form a functional coating. In addition, if a scrap film that did not become a product (for example, a film end portion cut and removed in a manufacturing process) is collected and used as a recycled material for film production, it is included in the recycled material during melt film formation. There are problems such as the coating film components being thermally degraded and the resulting film being markedly colored and lacking practicality (recoverability is poor). In addition, disadvantages such as difficulty in peeling (blocking) between the films and easiness of shaving of the coating film occur, and a solution to the problem is desired.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to apply an antistatic coating at low processing cost without performing a pretreatment such as a corona discharge treatment. In addition to having excellent antistatic properties, back transferability, abrasion resistance, blocking resistance, and recoverability, it has excellent adhesion to the thermosensitive coloring layer, excellent leuco dye coloring properties, and excellent transparency in the thermosensitive coloring layer support. To provide a laminated film for use.

[0010]

According to the present invention, an object of the present invention is a film in which a coating film is laminated on at least one side of a polyester film, wherein the coating film is (A) a binder resin 40 to 85. (B) 5 to 50% by weight of an antistatic agent mainly composed of a repeating unit having a structure represented by the following formula (1) (C) 5 to 20% by weight of a water-soluble polymer and (D) a surfactant This is achieved by a laminated film for a heat-sensitive coloring layer support, which is an antistatic coating film obtained by applying an aqueous coating solution containing a composition comprising 5 to 15% by weight, drying and stretching.

[0011]

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(Wherein R ¹ and R ² are each H
Or CH ₃ and R ³ are an alkylene group having 4 to 10 carbon atoms;
R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 to 5 carbon atoms, R ⁶ is an alkylene group having 2 to 5 carbon atoms, and m is 1 to 2
The number of 0, n is a number of 1 to 40, and Y ⁻ is a halogen ion, a mono- or poly-halogenated alkyl ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, a sulfonate ion or an alkyl sulfonate ion. Hereinafter, the present invention will be described in detail.

(Polyester Film) In the present invention, the polyester constituting the polyester film is a linear saturated polyester comprising a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and the like. it can. Particularly, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred from the viewpoint of the mechanical properties of the film.

The glycol components include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, polyethylene glycol. And the like. Particularly, ethylene glycol is preferred from the viewpoint of the rigidity of the film.

The polyester film used for the laminated film of the present invention has a haze value of 0.5 to 3.0% and a thickness of 20%.
It is preferably a transparent polyester film having a thickness of 200 μm.

In addition to the polyester film, inorganic fine particles such as silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, titanium oxide, barium sulfate, etc., cross-linked silicone resin, cross-linked polystyrene resin, cross-linked acrylic resin Organic fine particles made of heat-resistant polymer such as urea resin, melamine resin, etc., other resins such as polyethylene, polypropylene, ethylene-propylene copolymer, olefinic ionomer, stabilizers, antioxidants, ultraviolet absorbers, fluorescent enhancers If necessary, a whitening agent or the like may be contained in an amount that does not impair the transparency.

In the present invention, the polyester film is
It is preferably a biaxially stretched film. Further, the thickness of the polyester film is preferably from 20 to 500 μm. The upper limit of the thickness of the film is more preferably 300 μm, particularly preferably 200 μm. If the thickness exceeds, for example, 500 μm, the film-forming properties tend to be inferior. On the other hand, the lower limit of the film thickness is 50
μm, more preferably 75 μm. If the thickness is less than 20 μm, the stiffness of the film may be weak, which is not preferable.

(Binder Resin) In the present invention, the antistatic coating film (hereinafter sometimes simply referred to as “coating film”) is
It contains a composition comprising (A) a binder resin, (B) an antistatic agent, (C) a water-soluble polymer, and (D) a surfactant, and the (A) binder resin is a copolymerized polyester resin or an acrylic copolymer. It is preferably at least one binder resin selected from the group consisting of a polymer and an acrylic-modified polyester.

The acid components constituting the copolymerized polyester resin include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid and phenylindanedicarboxylic acid. Acids, dimer acids and the like can be exemplified. Two or more of these components can be used. Furthermore, maleic acid, fumaric acid,
An unsaturated polybasic acid such as itaconic acid or a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p- (β-hydroxyethoxy) benzoic acid can be used in a small proportion. The proportion of the unsaturated polybasic acid component or hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less. Further, as the polyol component, ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol,
1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, poly (ethyleneoxy) glycol, poly (tetramethyleneoxy) glycol, and the following formula (2) ) Or equation (3)
And ethylene oxide adducts and propylene oxide adducts of bisphenol A. Two or more of these can be used.

[0020]

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(However, p + q = 2 to 10, PH = phenylene group)

[0022]

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(However, p + q = 2 to 10, PH = phenylene group) Among such polyol components, ethylene glycol, ethylene oxide adduct of bisphenol A, propylene oxide adduct, and 1,4-butanediol are preferable. Further, ethylene oxide adduct of ethylene glycol and bisphenol A and propylene oxide adduct are preferable.

Further, the copolymerized polyester resin includes:
In order to facilitate aqueous liquefaction, it is possible to copolymerize a small amount of a compound having a sulfonic acid group or a compound having a carboxylic acid group, which is more preferable.

Examples of the compound having a sulfonate group include 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-Na sulfoisophthalic acid, 4-methylammonium sulfoisophthalic acid,
Na sulfoisophthalic acid, 5-K sulfoisophthalic acid,
Preferable examples include alkali metal sulfonic acid salts such as 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, and sodium sulfosuccinic acid, and amine sulfonic acid salts. Examples of the compound having a carboxylic acid group include, for example, trimellitic anhydride, trimellitic acid, pyromellitic anhydride, pyromellitic acid, trimesic acid, cyclobutanetetracarboxylic acid, dimethylolpropionic acid, etc. Metal salts and the like. The free carboxyl group is converted to a carboxylate group by the action of an alkali metal compound or an amine compound after copolymerization.

Such a copolymerized polyester resin can be produced by a conventionally known or used polyester production technique. For example, 2,6-naphthalenedicarboxylic acid or its ester-forming derivative (especially dimethyl ester), isophthalic acid or its ester-forming derivative (especially dimethyl ester) and trimellitic anhydride are propylene oxide adducts of ethylene glycol and bisphenol A To form a monomer or oligomer, followed by a polycondensation reaction under vacuum to obtain a predetermined intrinsic viscosity (intrinsic viscosity measured at 35 ° C. with o-chlorophenol of 0.3).
(Preferably 2 to 0.8 dl / g)), and further, a free carboxy group is reacted with an alkali compound or an amine compound to form a salt. At that time, it is preferable to use a catalyst for accelerating the reaction, for example, an esterification or transesterification catalyst, a polycondensation catalyst, and the like, and various additives such as a stabilizer can be added.

The above-mentioned copolymerized polyester resin can be used as a modified polyester copolymer, for example, a block polymer or a graft polymer obtained by modifying the above-mentioned copolymerized polyester with acrylic, polyurethane, silicone, epoxy or phenol resin. Of these, acrylic-modified polyester copolymers are preferred.

In the present invention, the constituent components of the acrylic copolymer (A) used as the binder resin include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, sodium acrylate, ammonium acrylate, 2-hydroxy Ethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, sodium methacrylate, ammonium methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, acrylic methacrylate, sodium vinyl sulfonate, sodium methallylsulfonate, styrene Sodium sulfonate, acrylamide,
Examples thereof include methacrylamide and N-methylol methacrylamide. These monomers can be used in combination with other unsaturated monomers such as styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, and divinylbenzene.

The acrylic copolymer may be a modified acrylic copolymer, for example, a block polymer or a graft polymer obtained by modifying the acrylic copolymer with polyester, polyurethane, silicone, epoxy, phenolic resin or the like. Can also.

(Antistatic Agent) The antistatic agent (B) in the present invention is a compound mainly composed of a repeating unit having a structure represented by the following formula (1).

[0031]

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(Wherein R ¹ and R ² are each H
Or CH ₃ and R ³ are an alkylene group having 4 to 10 carbon atoms;
R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 to 5 carbon atoms, R ⁶ is an alkylene group having 2 to 5 carbon atoms, and m is 1 to 2
The number of 0, n is a number of 1 to 40, and Y ⁻ is a halogen ion, a mono- or poly-halogenated alkyl ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, a sulfonate ion or an alkyl sulfonate ion. ) Among the above antistatic agents, Y ⁻ in the formula (1) is an alkylsulfonate ion represented by R ⁷ SO ₃ ^— (where R ⁷ is a saturated hydrocarbon group having 1 to 5 carbon atoms); - ^(OR 3) m- of ^{R 3} is an ethylene group, the number of m is ^{1~20, - (R 6 O)} R 6 in n- is an ethylene radical, n is a number from 1 to 40 Those are preferred because they have good adhesion between the coating film and the polyester film and heat resistance of the coating film, and particularly have excellent antistatic properties.

Particularly, the above antistatic agent is represented by Y in the formula (1).
^— Is CH ₃ SO ₃ ⁻ , C ₂ H ₅ SO ₃ ⁻ , or C ₃
H ₇ SO ₃ ^— , where — (OR ³ ) m— is — (OC ₂ H
₅ ) m- and m is preferably 1 to 5. Also, - ^(R 6 O) n- is _{- (C 2} H 5 O) a n-, and n is preferably 1 to 10.

The antistatic agent can be preferably produced, for example, by the following method. That is, the acrylate monomer is subjected to emulsion polymerization to obtain a weight average molecular weight of 2
000 to 100,000 polyacrylate and
Then, N, N-dialkylaminoalkylamine (for example, N, N-dimethylaminopropylamine, N, N-
Amidation by reaction with diethylaminopropylamine or the like) and finally a quaternary hydroxyalkylation reaction to introduce a quaternary cation pair.

Average molecular weight of antistatic agent (number average molecular weight)
Is arbitrary, but is preferably 3000 to 300,000. The lower limit of the average molecular weight is more preferably 5,000, and the upper limit is more preferably 100,000. When the average molecular weight is less than 3,000, the back transferability of the antistatic agent tends to deteriorate, while when the average molecular weight exceeds 300,000, the viscosity of the aqueous coating solution becomes too high, making it difficult to uniformly coat the film. Therefore, it is not preferable.

(Water-soluble polymer) The water-soluble polymer (C) in the present invention is a polymer soluble in water, and preferably includes polyvinyl alcohol and polyvinyl pyrrolidone.

The polyvinyl alcohol has a saponification degree of 75.
It is preferably about 95 mol%. If the saponification degree is less than 75 mol%, the moisture resistance of the coating film may be reduced, while if it exceeds 95 mol%, the adhesion to the ink image receiving layer may be reduced. Further, polyvinyl alcohol is preferably cation-modified because of good adhesion to the thermosensitive coloring layer.

Polyvinylpyrrolidone has a K value of 26 to 1.
00 is preferred. If the K value is less than 26, the strength of the coating film may be weak. If the K value exceeds 100, the adhesiveness to the thermosensitive coloring layer may be reduced. In addition, polyvinyl alcohol and polyvinylpyrrolidone are preferable if the average molecular weight is 10,000 or more because the coating film has excellent abrasion resistance.

(Surfactant) The antistatic film according to the present invention comprises (D) an interface in order to strengthen the adhesion between the coating film and the polyester film and to improve the blocking resistance of the laminated film. An activator is incorporated. Examples of the surfactant include an alkylene oxide homopolymer, an alkylene oxide copolymer, an aliphatic alcohol / alkylene oxide adduct, a long-chain aliphatic substituted phenol / alkylene oxide addition polymer, a polyhydric alcohol aliphatic ester, Nonionic surfactants such as chain aliphatic amide alcohols, compounds having a quaternary ammonium salt, compounds having an alkylpyridinium salt, and cationic or anionic surfactants such as a compound having a sulfonate can be given. In particular, a nonionic surfactant is preferable because it has excellent effects on the adhesion between the coating film and the base film and the blocking resistance of the antistatic polyester film.

(Antistatic Coating) The antistatic coating according to the present invention comprises (A) at least one side of a polyester film.
40 to 85% by weight of a binder resin, (B) the formula (1)
5 to 50% by weight of an antistatic agent mainly composed of a repeating unit having a structure represented by the following formula: (C) 5 to 20% by weight of a water-soluble polymer
And (D) an aqueous coating solution containing a composition comprising 5 to 15% by weight of a surfactant, followed by drying and stretching.

In the present invention, the proportion of the binder resin (A) in the composition contained in the aqueous coating liquid is from 40 to 85% by weight, preferably from 50 to 80% by weight. If this ratio is less than 40% by weight, the adhesion of the coating film to the polyester film is insufficient. On the other hand, when the content exceeds 85% by weight, the blocking property of the coated film deteriorates.

The proportion of the antistatic agent (B) in the composition contained in the aqueous coating solution is 5 to 50% by weight, preferably 10 to 40% by weight. If the proportion is less than 5% by weight, the antistatic property is insufficient, while if it exceeds 50% by weight, the adhesion of the coating film to the polyester film is insufficient.

The proportion of the water-soluble polymer (C) in the composition contained in the aqueous coating solution is 5 to 20% by weight, preferably 1 to 20% by weight.
0 to 15% by weight. If this proportion is less than 5% by weight, the adhesion to the thermosensitive coloring layer is insufficient, while if it exceeds 20% by weight, the blocking resistance is undesirably reduced.

The proportion of the surfactant (D) in the composition contained in the aqueous coating liquid is 5 to 15% by weight, preferably 5 to 15% by weight.
10% by weight. If this proportion is less than 5% by weight, the wettability of the aqueous coating liquid to the polyester film may be insufficient, while if it exceeds 15% by weight, the adhesion of the coating film to the polyester film may be insufficient or the blocking resistance may be poor. There is a shortage, which is not preferable.

In the present invention, the composition of the above components for forming a coating film is preferably applied as an aqueous coating liquid (using water as a medium), but it is also possible to apply an organic solvent as a solvent. Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, and isopropanol. These can be used alone or in combination of two or more.

In the present invention, a coating film is applied using an aqueous coating solution containing the above-mentioned composition. The aqueous coating solution has good slipperiness on the coating film surface and has good blocking resistance. In order to improve the properties, it is preferable to add a lubricant within a range that does not impair properties such as adhesiveness. Preferred examples of the lubricant include fine particles of, for example, polystyrene resin, acrylic resin, melamine resin, silicone resin, fluorine resin, urea resin, benzognamine resin, polyamide resin, polyester resin, and the like. The fine particles of these resins may be thermoplastic or thermosetting as long as the fine particles are contained in the coating film. The average particle size of the fine particles is preferably from 0.01 to 0.1 μm, and the compounding amount is preferably from 1 to 20% by weight.

Further, the aqueous coating solution may contain other surfactants, ultraviolet absorbers, pigments, lubricants, anti-blocking agents, cross-linking agents such as melamine, epoxy, aziridine and the like as long as the object of the present invention is not impaired. Other additives such as an antistatic agent can be blended.

The solid content concentration in the aqueous coating solution in the present invention is usually 30% by weight or less, but is preferably 0.5 to 30% by weight.
Is preferably within the range. 0.5% by weight
If the amount is less than 30%, the coatability on the polyester film may be insufficient, and if the amount is more than 30% by weight, the appearance of the coating film may be deteriorated.

The coating film of the present invention has a surface acidity of 5.
It is preferably 7 to 13. The upper limit of the surface acidity is more preferably 10, and particularly preferably 9.5. If the surface acidity exceeds 13, coloration of the diazo dye may occur, which is not preferable. On the other hand, the lower limit of the surface acidity is more preferably 6.0,
6.3 is particularly preferred. If the surface acidity is less than 5.7, the leuco dye may develop color before it is used as a medical diagnostic film, which is not preferable.

The coating film of the present invention has a surface resistivity of 3 × 10 ¹² Ω / □ at 23 ° C. and a relative humidity of 60%.
Or less, more preferably 3 × 10 ¹¹ Ω / □ or less, particularly preferably 3 × 10 ¹⁰ Ω / □ or less. When the surface specific resistance exceeds 3 × 10 ¹² Ω / □, the antistatic effect is small, and dust adheres in a process such as printing, which may cause a printing defect, and the transportability when used as a film for medical diagnosis. The probability of getting worse increases.

(Coating of Coating Film) In the present invention, an aqueous coating liquid containing the above-mentioned components is applied to at least one surface of a polyester film, and the film is preferably a polyester film before the crystal orientation is completed. As the polyester film before the completion of the oriented crystal, an unstretched film obtained by hot-melting the polyester to form a film, a uniaxial stretching in which the unstretched film is oriented in either the longitudinal direction or the transverse direction. Examples of the film include a film which is stretched and oriented at a low magnification in two directions of a longitudinal direction and a transverse direction (a biaxially stretched film before being finally stretched in a longitudinal direction and a transverse direction to complete orientation crystallization). Can be.

As a method of applying the aqueous coating solution to the polyester film, any known coating method can be applied. For example, roll coating, gravure coating, microgravure coating, reverse coating, roll brushing,
It is preferable to apply a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like, alone or in combination. When an aqueous coating liquid is used, a small amount of an organic solvent may be contained for the purpose of assisting the stability of the coating liquid.

The coating amount is preferably 0.5 to 50 g, more preferably 5 to 30 g, per m ² of the running film. The thickness of the final dried coating film (coating) is 0.02 to 1 μm
Is required, and the thickness is preferably 0.05 to 0.8 μm. When the thickness of the coating film is less than 0.02 μm, the antistatic property becomes insufficient. On the other hand, when the thickness exceeds 1 μm, the blocking resistance decreases, which is not preferable. Coating can be performed on only one side or on both sides depending on the use of the film. After coating, the coating is dried to form a uniform coating.

In the present invention, after the aqueous coating solution is applied to the polyester film, drying, preferably stretching treatment is carried out. This drying is preferably carried out at 90 to 130 ° C. for 2 to 20 seconds. This drying can serve as a pre-heat treatment for the stretching treatment or a heat treatment for the stretching. The stretching process of the polyester film is preferably performed at a temperature of 70 to 140 ° C. in a lengthwise direction of 2.5 to 7 times, in a horizontal direction of 2.5 to 7 times, and in an area magnification of 8 times or more, and more preferably 9 to 28 times. preferable. When re-stretching, it is preferable to stretch at a magnification of 1.05 to 3 times (however, the area magnification is the same as described above). The heat-setting treatment after stretching is performed at a temperature higher than the final stretching temperature and below the melting point.
It is preferably performed for 30 seconds. For example, in the case of a polyethylene terephthalate film, it is preferable to heat set at 170 to 240 ° C. for 2 to 30 seconds.

The thus-obtained laminated film for a heat-sensitive coloring layer support has, for example, a surface acidity of 5.7 to 13, especially 6.3 to 9.5, and a surface resistivity (temperature of 23).
(° C., humidity 60%) is 3 × 10 ¹² [Ω / □] or less, particularly 2 × 10 ¹⁰ to 2 × 10 ¹¹ [Ω / □], and has antistatic properties, blocking resistance, backside transfer properties, and abrasion resistance. It has excellent properties and recoverability, has excellent leuco dye coloring properties, and excellent adhesion to the thermosensitive coloring layer, and is useful as a medical diagnostic film.

[0056]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The evaluation in the present invention was performed by the following method. The average molecular weight indicates a number average molecular weight.

1. Surface resistivity (antistatic property) The surface resistivity of the sample film was measured by Takeda Riken Co., Ltd.
Using a specific resistance measuring instrument, measured temperature 23 ° C, measured humidity 6
Under the condition of 0%, the surface specific resistance value ρs (Ω / □) after one minute at an applied voltage of 500 V is measured, and the antistatic property is evaluated based on the following criteria from the obtained results. ◎: ρs ≦ 3 × 10 ¹¹ (extremely good antistatic property) ○: 3 × 10 ¹¹ <ρs ≦ 3 × 10 ¹² (good antistatic property) Δ: 3 × 10 ¹² <ρs ≦ 3 × 10 ¹³ (antistatic property) ×: 3 × 10 ¹³ <ρs (poor antistatic property)

2. Surface acidity A film sample with an area of 30 cm ² is 1 cm square (area 1
cm ² ). Cut the cut film sample into MEK (methyl ethyl ketone) / ion exchange water (pH =
6.8) Ultrasonic treatment with 500 ml of 1/1 solution for 30 minutes. The film sample is removed, the solution is extracted with 500 ml of ion-exchanged water, and water is separated by a separating funnel. The pH of the separated water is measured with a pH meter (Toa Denpa Kogyo Co., Ltd.)
HM-30S).

3. Blocking resistance The coated and uncoated surfaces of the sample film cut to a width of 50 mm were overlapped. Under a load of 50 kg / cm ² ,
After treatment at 60 ° C. × 80% RH for 17 hours, the peeling force between the coated surface and the non-coated surface is measured, and the blocking resistance is evaluated as follows. Rank A: Peeling force ≦ 10 g (good blocking resistance) Rank B: 10 g <peeling force ≦ 30 g (slightly poor blocking resistance) Rank C: 30 g <peeling force (poor blocking resistance)

4. Back transferability 6
After applying a load of kg / cm ² and treating at 50 ° C. × 70% RH for 17 hours, the water contact angle (θ: substitute property of backside transferability) of the uncoated surface was measured, and according to the following criteria. evaluate. Rank A: θ ≧ 55 ° (backside transferability is good) Rank B: 55 °> θ ≧ 48 ° (backside transferability is somewhat good) Rank C: 48 °> θ (backside transferability is poor) The water contact angle is the above sample film Was set on a contact angle measuring device (manufactured by Elma) with the uncoated surface facing up, and the temperature was set to 23.
It measures by reading the contact angle 1 minute after dropping a water drop under the condition of ° C. The water contact angle of a film having no backside transferability is 60 to 72 °, the water contact angle of a film having good backside transferability is 55 ° or more, and a film having a remarkable backside transferability (poor backside transferability). Has a water contact angle of less than 48 °.

5. Using a film sample cut to a width of 20 mm, the coated surface of the film was applied to a cylindrical stainless steel fixed bar having a diameter of 10 mm, and was run for 80 m under a load of 200 g. Observe the white powder of the film and evaluate the abrasion resistance as follows. Rank A: No white powder adhered to the bar (good abrasion resistance) Rank B: White powder slightly adhered to the bar (slightly poor abrasion resistance) Rank C: Large amount of white powder adhered to the bar (poor abrasion resistance)

6. Degree of coloring (recovery) of regenerated film A film without a coating film is pulverized, and extruded to about 300
The mixture is melted at 0 ° C. to form chips, and then the obtained chips are melt-formed to form a blank film. The coloring degree of this film is defined as a blank. On the other hand, a sample film provided with a coating film is pulverized, melted at about 300 ° C. with an extruder to form chips, and then melt-formed using the obtained chips to produce a regenerated film. The degree of coloring of this film is evaluated according to the following criteria. Rank A: The degree of coloring is similar to that of a blank film. Rank B: The film is slightly colored. Rank C: The degree of coloring of the film is large and lacks practicality.

7. Adhesive property of thermosensitive coloring layer A polyester film having a thickness of 250 µm is attached to the non-coated surface of the sample with an adhesive. A thermosensitive coloring layer coating solution (a, b, c liquid) was used on the coating film surface, and the solid content was 3.0 g / m ^2.
Was applied and dried to form a thermosensitive coloring layer having a thickness of 3.0 μm. (Solution a) A mixture of 4 parts by weight of 3-diethylamino-6-methyl-7-anilinofluoran and 10 parts by weight of a 5% aqueous solution of polyvinyl alcohol was dispersed using a sand grinder so as to have an average particle diameter of 0.4 μm. A dispersion solution was prepared. (Solution b) A mixture of 8 parts by weight of p-hydroxybenzoic acid benzyl ester and 20 parts by weight of a 5% aqueous solution of polyvinyl alcohol was subjected to an average particle diameter of 0.4 μm using a sand grinder.
To prepare a dispersion solution. (Liquid c) 5% aqueous solution of polyvinyl alcohol The above liquids a, b, and c were mixed in equal amounts to prepare a thermosensitive coloring layer coating liquid.

On the above-mentioned thermosensitive coloring layer, a cellophane tape (18 m
m width; made by Nichiban) to a length of 15 cm, apply a constant load on it with a 2 kg hand-operated load roll, fix the film, and peel off one end of the cellophane tape in the 90 ° direction. Evaluate the power. Adhesion is evaluated according to the following criteria. Rank A: The heat-sensitive coloring layer is not peeled at all (good adhesion). Rank B: The coating film and the heat-sensitive coloring layer are partially peeled off in a cohesive failure state (adhesion is slightly good). Peeled in layers (poor adhesion)

8. Leuco dye coloring property The following leuco dye paint is applied on the coating film of the sample film, dried at 80 ° C, and the presence or absence of coloring of the applied coating film (leuco coloring layer) is evaluated. ：: no color formation ×: color formation Preparation of leuco dye-based paint 2.5 parts by weight of compound represented by the following formula, bis (4-hydroxyphenyl) acetic acid methyl ester 5.0 parts by weight, 5
-25.0 parts by weight of an aqueous solution of hydroxyethyl cellulose,
5.0 parts by weight of stearic acid amide, 42.0 parts by weight of a polyurethane-based binder and 73.5 parts by weight of water were uniformly mixed to prepare a leuco dye-based coating.

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Example 1 Intrinsic viscosity (measured at 35 ° C. in an orthochlorophenol solution: unit: dl / g) 0.65
A composition comprising 99.6% by weight of polyethylene terephthalate (PET) and 0.4% by weight of spherical silica having an average particle size of 1.2 μm was melted by an extruder, extruded into a sheet on a cooling drum and cast. A stretched film was obtained. Next, this unstretched film was stretched 3.6 times in the machine direction.
Terephthalic acid (22 mo) is applied to one side of this uniaxially stretched film.
1%), isophthalic acid (1 mol%), 2,6-naphthalenedicarboxylic acid (65 mol%), 4,4'-diphenyldicarboxylic acid (12 mol%), ethylene glycol (75 mol%), 1,4-cyclohexanedimethanol (10 mol%), a propylene oxide adduct of bisphenol A represented by the following formula (4) (15 mol%)
%) (Tg = 8)
0 ° C., average molecular weight = 2,500) (A-1) 60% by weight, polymer antistatic agent having a repeating unit represented by the following formula (5) (average molecular weight = 12,000), (B-1) 20% by weight 4 g of a 10% by weight aqueous liquid having a solid composition composed of 10% by weight of polyvinyl alcohol (C-1) having a saponification degree of 86 to 89 mol% and 10% by weight of polyoxyethylene nonylphenyl ether (D-1). / M ² (wet) with a coating amount of microgravure coating on one side of the film. After drying, stretched 3.6 times in the transverse direction,
To obtain a laminated film having a thickness of 100 μm and a coating thickness of 0.03 μm (an antistatic coating laminated biaxially stretched polyester film). Table 2 shows the properties of the coating surface of the laminated film. The laminated film has a haze of 1.2.
%, Which was useful for a medical diagnostic laminated film.

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Example 2 Copolymerized polyester resin (A
-1) with methyl methacrylate (30 mol%), ethyl acrylate (55 mol%), acrylonitrile (10
mol%) and N-methylol methacrylamide (5 m
ol%), a laminated film was obtained in exactly the same manner as in Example 1, except that the acrylic copolymer (number average molecular weight: 258,000) (A-2) was prepared. Table 2 shows the properties of the coating surface of the laminated film.

Example 3 The solid content of the copolymer polyester resin (A-1) was 30% by weight, and the acrylic copolymer (A
-2) 30% by weight, 20% by weight of the polymer antistatic agent (B-1) represented by the formula (5), 10% by weight of polyvinyl alcohol (C-1) having a saponification degree of 86 to 89% by mole, and Polyoxyethylene nonyl phenyl ether (D-1)
A laminated film was obtained in exactly the same manner as in Example 1, except that the composition was changed to 10% by weight. Table 2 shows the properties of the coating surface of the laminated film.

Example 4 A polymer antistatic agent was changed to a polymer antistatic agent having a repeating unit represented by the following formula (6) (average molecular weight = 8,000) (B-2). A laminated film was obtained in exactly the same manner as in Example 3. Table 2 shows the properties of the coating surface of the laminated film.

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Example 5 The solid content was 35% by weight of the copolymerized polyester resin (A-1) and the acrylic copolymer (A
-2) polyvinylpyrrolidone (C-2) having 35% by weight, 10% by weight of the polymer antistatic agent (B-1) represented by the formula (5), a K value of 26 to 23, and an average molecular weight of 40,000.
A laminated film was obtained in exactly the same manner as in Example 1 except that the composition was changed to 10% by weight and 10% by weight of polyoxyethylene nonylphenyl ether (D-1). Table 2 shows the properties of the coating surface of the laminated film.

Examples 6 to 10 Laminated films were obtained in exactly the same manner as in Example 1 except that the solid content composition was changed to the composition shown in Table 1. Table 2 summarizes the properties of the coating surface of this laminated film.

Example 11 A laminated film was obtained in the same manner as in Example 1 except that polyethylene terephthalate (PET) was changed to polyethylene naphthalate (PEN) having an intrinsic viscosity of 0.60 (dl / g). Table 2 shows the properties of the coating surface of this film.

Comparative Example 1 The solid content was 45% by weight of the copolymerized polyester resin (A-1), 45% by weight of the acrylic copolymer (A-2), the K value was 26 to 23, and the average molecular weight was 40,000. A laminated film was obtained in exactly the same manner as in Example 1 except that the composition was changed to 5% by weight of polyvinylpyrrolidone (C-2) and 5% by weight of polyoxyethylene nonylphenyl ether (D-1). Table 2 shows the properties of the coating surface of this film.

[Comparative Example 2] The solid content composition was changed to methyl methacrylate (30 mol%) and ethyl acrylate (55 mol%).
%), N-methylol methacrylamide (5 mol%)
Copolymer (number average molecular weight: 26400) prepared from methacrylic acid (10 mol%) (A-3)
35% by weight, 40% by weight of the polymer antistatic agent (B-1) represented by the formula (5), 15% by weight of polyvinylpyrrolidone (C-2) having a K value of 26 to 23 and an average molecular weight of 40000, and A laminated film was obtained in exactly the same manner as in Example 1, except that the composition was changed to 10% by weight of polyoxyethylene nonylphenyl ether (D-1). Table 2 shows the properties of the coating surface of this film.

Comparative Example 3 A laminated film was obtained in exactly the same manner as in Example 1 except that the antistatic agent was changed to sodium polystyrene sulfonate (B-3). Table 2 shows the properties of the coating surface of this film.

[Comparative Example 4] Except that the antistatic agent was changed to sodium dodecylbenzenesulfonate (B-4),
A laminated film was obtained in exactly the same manner as in Example 1. Table 2 shows the properties of the coating surface of this film.

Comparative Example 5 Table 2 shows the surface characteristics of the biaxially stretched polyester film obtained in Example 1 without coating the composition.

Comparative Examples 6 to 9 Laminated films were obtained in exactly the same manner as in Example 1 except that the solid content composition was changed to the composition shown in Table 1. Table 2 shows the properties of the coating surface of this film.

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[Table 1]

In Table 1, the type of coating composition A-
1, A-2, A-3, B-1, B-2, B-3, B-
4, C-1, C-2 and D-1 indicate the following compounds.

A-1: Terephthalic acid (22 mol%),
Isophthalic acid (1 mol%), 2,6-naphthalenedicarboxylic acid (65 mol%), 4,4'-diphenyldicarboxylic acid (12 mol%), ethylene glycol (75
mol%), 1,4-cyclohexanedimethanol (1
0 mol%), a copolymerized polyester resin (Tg = 80 ° C., average molecular weight = 21,500) made from a propylene oxide adduct of bisphenol A represented by the above formula (4) (A-2): acrylic acid Acrylic copolymer (number average molecular weight: 258000) prepared from ethyl (55 mol%), acrylonitrile (10 mol%) and N-methylol methacrylamide (5 mol%) A-3: Methyl methacrylate (30 mol%), acrylic acid Ethyl (55 mol%), N-methylol methacrylamide (5 mol%) and methacrylic acid (10 mol
%) And an acrylic copolymer (number average molecular weight:
26400) B-1: Polymer antistatic agent represented by the above formula (5) (average molecular weight = 12,000) B-2: Polymer antistatic agent represented by the above formula (6) (average molecular weight = 8, 000) B-3: Sodium polystyrene sulfonate B-4: Sodium dodecylbenzene sulfonate C-1: Saponification degree 86-89 mol%, average molecular weight 15
2,000 polyvinyl alcohol C-2: polyvinylpyrrolidone D-1 polyoxyethylene nonyl phenyl ether having a K value of 26 to 23 and an average molecular weight of 40,000

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[Table 2]

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According to the present invention, the laminated film for a heat-sensitive coloring layer support has no coloring such as leuco dye, is excellent in antistatic property under low humidity, and has anti-blocking properties and backside transfer as compared with conventional ones. It has excellent heat resistance, abrasion resistance, and recoverability, and is useful for a film for an image output medium having a thermosensitive coloring layer such as a film for medical diagnosis.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 139/06 C09K 3/16 104 C09K 3/16 104 108 108 B41M 5/18 HLF term (Reference) 2H026 AA07 BB01 EE05 4F100 AH03B AK01B AK02B AK21B AK25B AK25J AK41A AK41B AK41J AK42A AL01B AL06B AR00B AS00B BA02 BA03 BA06 BA13 CA18B CA22B EH46 EH46B EJ38 GB90 JB09B JG03 JL00 JM02B JN01 JN01A YY00A YY00B 4J004 CA03 CA06 CC03 CD05 CD06 FA09 4J038 CC091 CE022 CG031 CG101 CG111 CG141 CG171 CG172 CH031 CK032 CR071 DD051 DD061 DD071 DD091 GA08 KA09 KA12 MA08 NA01 NA10 NA12 NA20 PB01 PC08

Claims (7)

[Claims] 1. A film in which a coating film is laminated on at least one side of a polyester film, wherein the coating film has (A) 40 to 85% by weight of a binder resin and (B) a structure represented by the following formula (1). 5 to 50% by weight of an antistatic agent mainly composed of a repeating unit, (C) 5 to 20 of a water-soluble polymer
A thermosensitive coloring layer support, characterized in that it is an antistatic coating film obtained by applying an aqueous coating liquid containing a composition consisting of 5% by weight and (D) 5 to 15% by weight of a surfactant, followed by drying and stretching. Laminated film for body. Embedded image (However, R ¹ and R ² in the formula are each H or CH ₃ ,
R ³ is an alkylene group having 4 to 10 carbon atoms, R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 to 5 carbon atoms, R ⁶ is an alkylene group having 2 to 5 carbon atoms, and m is 1 to 20. N is 1
40 Number of, Y ^- is a halogen ion, a mono- or polyhalogenated alkyl ion, nitrate ion, sulfate ion, alkyl sulfate ion, sulfonate ion or an alkyl sulfonate ion. ) 2. The antistatic coating film has a surface acidity of 5 to 13 and a surface resistivity of 3 × 1 at 23 ° C. and a relative humidity of 60%.
0 ¹² Ω / □ or less coloring layer supporting-body laminate film according to claim 1. 3. The laminated film for a thermosensitive coloring layer support according to claim 1, wherein (A) the aqueous binder is at least one selected from the group consisting of a copolymerized polyester resin, an acrylic copolymer, and an acrylic-modified polyester. 4. The laminated film according to claim 1, wherein (C) the water-soluble polymer is at least one selected from the group consisting of polyvinyl alcohol and polyvinylpyrrolidone. 5. The polyester film is a polyethylene terephthalate film or polyethylene-2,6-
The laminated film for a thermosensitive coloring layer support according to claim 1, which is a naphthalate film. 6. A polyester film having a haze value of 0.1.
The laminated film for a heat-sensitive coloring layer support according to claim 1, which is a transparent polyester film having a thickness of 5 to 3.0% and a thickness of 20 to 200 m. 7. A laminated film for medical diagnosis, comprising a thermosensitive coloring layer provided on at least a part of the antistatic coating film of the laminated film according to claim 6.