JP3136717B2 - Polyester film and photosensitive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymerized polyester film, and more particularly to a polyester having excellent transparency, water absorption and mechanical properties useful as a support or cover layer of a photographic light-sensitive material. It is about film.

[0002]

2. Description of the Related Art Photosensitive materials include those in the form of X-ray films, plate making films and cut sheets, and those in the form of roll films. A typical roll film is a color or black-and-white negative film that is housed in a patrone with a width of 35 mm or less and is loaded into a general camera and used for photographing.

[0003] Photographic light-sensitive materials are generally manufactured by coating at least one photographic light-sensitive layer on a plastic film support. As this plastic film, triacetyl cellulose (hereinafter referred to as "T
AC ") and a polyester polymer such as polyethylene terephthalate (hereinafter referred to as" PET ") (Fiber and Industry, 41 (9), 329-324). ).

A TAC film is a film formed by a solution casting method using methylene chloride as a main solvent, and has a small optical anisotropy and excellent transparency and flatness. Also, since it has an appropriate water absorption, it also has excellent properties in curling elimination after development processing. In other words, the film is rolled and curled by being aged over time in the state of being wound as a roll film.However, the mobility of the molecular chains increases due to the absorption of water in the developing process, and the molecular chains fixed over time become rearranged. As a result, the curl is eliminated.

In a photographic photosensitive material using a film having no curl recovery property such as a TAC film, when used in a roll state, for example, in a printing process for forming an image on photographic printing paper after development, etc. This causes problems such as scratches, defocusing, and jamming during transport.
Therefore, TAC films have been widely used as photographic light-sensitive materials.

[0006] In recent years, however, the applications of photographic light-sensitive materials have been diversified, and the speed of unwinding a film at the time of photographing, the increase in photographing magnification, and the miniaturization of photographing devices have been remarkably progressing. Therefore, a support for a photographic material has been required to have properties such as mechanical properties, dimensional stability, and thinning.

A biaxially stretched PET film has excellent transparency, mechanical properties, and dimensional stability, and is a microfilm that requires a thin film, and a printing feeling that requires strict dimensional stability. For the material, a PET film is used instead of the TAC film. However, in the case of the PET film, the water absorption is small, and the curl recovery property of the roll like a TAC film is small, so that the handleability after the development processing is poor, and the use range is limited while having the above excellent characteristics. .

[0008]

That is, the object of the present invention is to maintain the transparency, mechanical properties, and dimensional stability of a PET film while maintaining the same water absorption as a TAC film, and furthermore, the curl of a TAC film. An object of the present invention is to provide a polyester film having curl recovery properties.

[0009]

The present invention has the following structure to solve the above-mentioned problems. That is, in the polyester film having a multilayer structure, the dicarboxylic acid copolymerization component of the polyester A constituting at least one layer thereof is represented by the formula (a) with an aromatic dicarboxylic acid having a metal sulfonate and / or a derivative thereof. a polyester film comprising a polyether dicarboxylic acid and / or derivatives thereof having an average molecular weight from 600 to 20,000 which
The polyester film is biaxially oriented,
When the haze value is 5% or less and the water content is 0.5% or more
Yes, heat shrinkage at 150 ° C for 30 minutes is 2% or less
A polyester film, characterized in that.

R ¹ OOCCH ₂ — (O—R ² ) _n —OCH ₂ COOR ³ (a) (R ¹ , R ³ : H or an alkyl group having 1 to 8 carbon atoms, R
² : an alkylene group having 2 to 8 carbon atoms, n: a positive integer) In the present invention, a layer composed of polyester A obtained by using an aromatic dicarboxylic acid component having a metal sulfonate and a polyether dicarboxylic acid component in combination is provided. In addition, a remarkable effect is brought about by multi-layering, thereby solving the problem of the present invention.

The copolymer polyester preferably used for the polyester A of the present invention is a copolymer polyester containing an aromatic dicarboxylic acid component having a metal sulfonate as a copolymer component.

As the aromatic dicarboxylic acid having a metal sulfonate, specifically, 5-sodium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid,
-Sodium sulfophthalic acid, 4-sodium sulfo-
Examples thereof include 2,6-naphthalenedicarboxylic acid and compounds obtained by substituting sodium thereof with another metal, for example, potassium, lithium, ammonium salt or phosphonium salt. The copolymerization ratio of the aromatic dicarboxylic acid component having a metal sulfonate is 2 to 20% by weight, preferably 5 to 15% by weight, particularly preferably 7 to 12% by weight, based on the reaction product polyester.

The fact that the polyester A used in the present invention is further copolymerized with a polyether dicarboxylic acid component represented by the formula (a) provides the film with transparency, dimensional stability, and mechanical strength. Is preferred. The average molecular weight of this polyether dicarboxylic acid is from 600 to 20,000
Is required, preferably in the range of 1,000 to 15,000, more preferably in the range of 2,000 to 10,000. When the average molecular weight is 600 or less, the water absorption becomes insufficient, and the curling recovery property cannot be sufficiently obtained. In order to obtain a roll recovery property comparable to that of a TAC film, a longer polyether chain is better, but a molecular weight of 20,000 or more is not preferred because the transparency and rigidity of the film decrease. As the polyether dicarboxylic acid, polyethylene oxydicarboxylic acid, polypropylene oxydicarboxylic acid, and polytetramethylene oxydicarboxylic acid are preferred, but polyethylene represented by the formula (b) is particularly preferred in view of the polymerization reactivity of the polyester and the dimensional stability of the film. Oxydicarboxylic acids are more preferred.

R ¹ OOCCH ₂ — (O—CH ₂ CH ₂ ) _n —OCH ₂ COOR ² (b) (R ¹ , R ² : H or an alkyl group having 1 to 8 carbon atoms,
(n: positive integer) The copolymerization ratio of the polyether dicarboxylic acid component is 2 to 20% by weight, preferably 5 to 15% by weight, particularly preferably 7 to 1% by weight, based on the polyester of the reaction product.
2% by weight.

The moisture content of the polyester film of the present invention was measured by adjusting the humidity of the film at 23 ° C. and 30% RH for 3 hours, and then immersing the film in distilled water at 23 ° C. for 15 minutes.
Then, a trace moisture meter (for example, Mitsubishi Kasei Co., Ltd. C
(A-20 type) at a drying temperature of 150 ° C.

The polyester film of the present invention is characterized in that the water content measured by such a method is 0.5% by weight or more, preferably 0.6 to 5.0% by weight.
If the water content is less than 0.5% by weight, the curl recovery property after development processing is not improved, and if the water content is too large, the dimensional stability due to moisture absorption deteriorates.

In the present invention, the polyester is a polyester containing an aromatic dibasic acid and a glycol as main components. Examples of the dibasic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and diphenylsulfone. Examples thereof include dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the glycol include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4
-Hydroxydiphenyl) propane, 2,2-bis (4
-Hydroxyethoxyphenyl) propane, bis (4-
(Hydroxyphenyl) sulfone, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters composed of these components, polyethylene terephthalate, polycyclohexane dimethylene terephthalate, and polyethylene naphthalate are preferred from the viewpoint of heat resistance, mechanical strength, dimensional stability, and the like.

In the polyester film of the present invention, it is possible to further copolymerize another acidic component or a glycol component as long as the ratio is small as long as the transparency and mechanical properties are not impaired. For example, as a dicarboxylic acid, a long-chain aliphatic dicarboxylic acid having an alkylene group having 8 to 60 carbon atoms, such as sebacic acid, eicoic acid, dodecane dicarboxylic acid, and dimer acid, and a polyethylene glycol having a molecular weight of about 600 to 20,000 as a glycol component. And polyalkylene glycols such as polytetramethylene glycol, and 0 to 10% by weight can be copolymerized.

In the multilayer structure of the polyester film of the present invention, when the layers other than the polyester A layer are the polyester B layer or the C layer, the polyester film of the present invention may have a two-layer structure of A / B. / A, B
/ A / B or B / A / C may be a three-layer structure,
Further, a multi-layer structure of more than that may be used. Since the polyester in the layer A is a copolymer, the crystallinity is lower than that of the homopolyester, and the mechanical properties, transparency, dimensional stability, etc. are lower. Therefore, the A layer, which is a copolymerized PET layer, and the PET layer or another homopolymer layer, or another copolymerized polymer layer are co-extruded to obtain the same transparency, mechanical properties, and dimensions as ordinary PET films. It is possible to provide a polyester film having water absorbency comparable to that of a TAC film while maintaining the stability, and further having a curl recovery property similar to that of a TAC film. Furthermore, even when imparting lubricity, coloring, antistatic properties, etc. to the surface of the film, the necessary additives may be added only to the surface layer, so that the high transparency of the film can be maintained, and the cost of the film itself can be reduced. It also leads to lowering.

First, A / B, B / A / B or B / A
The / C structure will be described. In the present invention, depending on the copolymerization ratio, precipitation of a low polymer may be a problem in the heat treatment when the undercoat layer is provided. In this case, a polyester B different from the A layer on one side or both sides of the A layer. By laminating the layers, the precipitation of the low polymer can be suppressed, and the transparency of the film can be maintained. As the polyester B layer, the above-mentioned polyester is preferably used, and polyethylene terephthalate, polycyclohexane dimethylene terephthalate, and polyethylene naphthalate are particularly preferable. The lamination thickness of the polyester B layer is 0.0
The thickness is preferably 5 to 20 μm, particularly preferably 0.5 to 10 μm, and further preferably 1 to 5 μm. In addition, the polyester film of the present invention is required to have water absorbency. Therefore, when polyester B having low water absorbency is used, it is necessary to reduce the thickness of the laminate within a range where precipitation of a low polymer can be suppressed. As another method, polyester B
Water absorption may be imparted to the layer itself. For example, it is preferable to use a copolymerized polyester having an aromatic dicarboxylic acid component having a metal sulfonate as a copolymerization component. Examples of the aromatic dicarboxylic acid having a metal sulfonate include the compounds described above. The copolymerization ratio is 1 to 20% by weight, preferably 3 to 12% by weight, particularly preferably 3 to 12% by weight, based on the polyester of the reaction product. 4 to 10% by weight. Further, a small amount of a polyether dicarboxylic acid, a polyalkylene glycol, a long-chain aliphatic dicarboxylic acid, or the like may be copolymerized as long as the mechanical properties and transparency of the film are not reduced. Further, a polyester in which low-polymerized substances are reduced by solid-phase polymerization may be used.

In the case of the A / B structure, it is particularly effective to prevent the deposition of low molecular weight substances on one side of the film.
Further, the curl curl of the film can be efficiently recovered by the difference between the curl recoverability of the layer A and the layer B at the time of water absorption.

Next, A / B / A will be described. In other words, the layer A may be laminated relatively thick on both sides of the layer B. In this case, the layer A has a curl recovery property, the layer B has a mechanical strength,
It has a function such as dimensional stability. As the polyester for the layer B, the above-mentioned polyesters are preferably used. However, the polyester B layer may have some water absorbing properties. For example, an aromatic dicarboxylic acid component having a metal sulfonate, a polyether dicarboxylic acid, or a polyalkylene glycol may be used. And a long-chain aliphatic dicarboxylic acid or the like may be used alone or in combination. The copolymerization ratio is 0 to 6% by weight based on the reaction product polyester.
Is preferred. If curl remains on the film,
It is clear that the amount of deformation near the surface of the film is large, but the amount of deformation is smaller at the center, but the curl recovery of the surface layer is increased, and the core layer provides some curl recovery. Conversely, a structure having mechanical strength and dimensional stability is very effective in balancing the characteristics of the film. However, low molecular weight substances such as oligomers may remain in the A layer polyester. For example, the low molecular weight substances can be reduced by solid phase polymerization. Precipitation of molecular weight substances may be prevented. That is, for example, a five-layer structure of C / A / B / A / C may be used. As the polyester of the C layer, the same polyester as that of the B layer is preferably used, but it is desired that the amount of the low polymer is small, and the lamination thickness thereof needs to be reduced within a range that can suppress the precipitation of the low polymer. . Of course C
Needless to say, the effect of imparting some water absorbency also to the layer.

The glass transition temperature of the polyester B layer is 6
The temperature is 0 ° C. or higher, preferably 65 ° C. or higher, more preferably 70 ° C. or higher. In the case of the present invention, since the strength of the polyester A layer is slightly lowered, the strength is maintained by laminating the polyester B layer having a relatively high glass transition temperature.

In the present invention, the thickness of the layer A is not particularly limited.
The thickness of the layer is preferably in the range of 1 to 99%.

When performing multi-layer lamination, this means is specifically a plurality of extruders and feed blocks,
Alternatively, a co-extrusion method using a multi-manifold die is exemplified.

The glass transition temperature of the polyester film of the present invention is preferably 50 ° C. or higher, more preferably 60 ° C.
That is all. Here, the film was measured by a differential scanning calorimeter on a film placed in an atmosphere of 25 ° C. and 50% RH. If the glass transition temperature is lower than 50 ° C., for example, the film may be deformed at a high temperature in summer, which is not preferable. The higher the glass transition temperature is, the higher the heat resistance is, of course, but the curl recovery is reduced. Therefore, it is necessary to improve the water absorption to lower the glass transition temperature at the time of water absorption. The glass transition temperature at the time of water absorption is 38 ° C.
Measured with a differential scanning calorimeter immediately after immersion in distilled water for 30 minutes, and is preferably 60 ° C. or lower, more preferably 50 ° C. or lower.

The haze value of the polyester film of the present invention is at most 5%, preferably at most 2%. When the haze value exceeds 5%, when a film is used as a photographic material, there is a problem that an image is blurred and becomes unclear.

One of the properties that poses a problem when a polyester film is used as a photographic light-sensitive material is a light piping phenomenon that occurs because the support has a high refractive index.
The refractive index of a TAC film is as small as 1.5, whereas the refractive index of a polyester film is as high as about 1.6. On the other hand, the refractive index of gelatin used exclusively for the undercoat layer and the photographic emulsion layer is 1.50 to 1.55, and the ratio of the refractive index of gelatin is 1.50 to 1.55 / 1 for TAC film. There is no problem because the ratio is larger than 0.5 and 1. However, in the case of polyester film, it is 1.5 / 1.6.
When light is incident from the film edge, it is easily reflected at the interface between the base film and the emulsion layer. For this reason, the light piping phenomenon occurs.

As a method of avoiding such a light piping phenomenon, a method of incorporating inert inorganic particles or the like into a film and a method of adding a dye are known.
The preferred method of preventing light piping in the present invention is a method by adding a dye which does not significantly increase the film haze.

The dye used for dyeing the film is not particularly limited, but the color tone is preferably gray dyeing due to the general properties of the light-sensitive material, and the dye has excellent heat resistance in the film-forming region of the polyester film. Further, those having excellent compatibility with polyester are preferable.

As the dye, Diaresin manufactured by Mitsubishi Kasei Co., Ltd., and Kae manufactured by Nippon Kayaku Co., Ltd.
The purpose can be achieved by mixing dyes commercially available for polyesters such as yaset.

Regarding the staining density, the color density in the visible region was measured with a color densitometer manufactured by Macbeth Co.
It must be at least one. More preferably 0.0
3 or more.

The polyester film according to the present invention includes:
It is also possible to impart lubricity according to the application, and there is no particular limitation on the means for imparting lubricity, but kneading of an inert inorganic compound, or application of a surfactant is common. Used as a technique.

The inert inorganic particles include Si
O ₂ , TiO ₂ , BaSO ₄ , CaCO ₂ , talc, kaolin and the like are exemplified. In addition to the lubricity imparted by the external particle system in which inert particles are added to the polyester synthesis reaction system described above, a lubricity imparting method using an internal particle system in which a catalyst or the like to be added during the polymerization reaction of the polyester is precipitated can also be adopted. It is.

Although there is no particular limitation on the means for imparting lubricity, transparency is an important requirement for the support for a photographic light-sensitive material. It is desirable to select SiO ₂ having a refractive index relatively close to that of the polyester film or an internal particle system capable of relatively reducing the particle diameter of the precipitated film. These particle systems may be added to any layer of the polyester film of the present invention, but are preferably added to the surface layer.

The polyester film 150 of the present invention
The heat shrinkage at 30 ° C for 30 minutes is2% or less, preferably
1.5% or less. TAC film and PET film
Has a small heat shrinkage of 2% or less,
Thermal shrinkage of polyester film tends to increase
However, the heat recovery of the copolymerized polyester film of the present invention
A major feature is that the shrinkage ratio is less than PET film.
You. When film is used as a support for photographic materials
If it is a hydrophobic polyester film or TAC film
Directly apply hydrophilic emulsion layer (gelatin binder)
However, the required adhesive strength cannot be obtained. So normal film
Has an undercoat layer, but in this step the film is
About 150 ° C. heat is applied. Also, dry the coated emulsion.
The drying step is heated at 100-150 ° C. Film
It is preferable that they do not deform or expand or contract in these steps.
That is, the film is required to have thermal dimensional stability.

The tear propagation resistance of the polyester film of the present invention is preferably 500 g / mm or more, more preferably 800 g / mm or more. Normally, the tear propagation resistance of a TAC film is as small as 200 to 400 g / mm, which is small enough to tear by hand. This property was necessary, for example, in the editing work of a movie film. It also caused tearing. Therefore, a high value of tear propagation resistance is required for ordinary photographic films.

The polyester film of the present invention has a breaking strength of 8 kg / mm ² or more, preferably 13 kg / mm ² or more.
g / mm ² or more. Furthermore, Young's modulus is 300kg
/ Mm ² or more, preferably 350 kg / mm ² or more. The Young's modulus when the polyester film was immersed in distilled water at 38 ° C. for 30 minutes was 260 kg /
mm ² or more, preferably 300 kg / mm ² or more. When the mechanical strength is reduced, the film may be easily deformed or broken by an external force during winding in a camera or automatic development and printing by a machine.

The raw material polymer for the copolymerized polyester film of the present invention can be synthesized according to a conventionally known polyester manufacturing method. For example, by directly esterifying an acidic component with a glycol component, or when using a dialkyl ester as the acidic component, performing a transesterification reaction with a glycol component, and heating this under reduced pressure to remove an excess glycol component. And a copolymerized polyester can be obtained. At this time, if necessary, a transesterification catalyst or a polymerization reaction catalyst may be used, or a heat stabilizer may be added. Of course, in practical use, anti-coloring agents, anti-oxidants, crystal nucleating agents, slip agents, stabilizers, anti-blocking agents, ultraviolet absorbers, viscosity modifiers, defoamers, clarifiers, antistatic agents, etc. Is also good.

The copolyester obtained above is generally molded into granules, dried, melted, and co-extruded from a T-die to form an unstretched sheet. When the molten polyester sheet is brought into contact with a cooling roll, it is preferable to apply an electrostatic application cooling method.

The obtained unstretched sheet can be used as it is, but when the sheet is extruded from the T-die, a streak is generated on the sheet surface. Therefore, when the sheet is used as a photographic film, the image is distorted by the streak. Therefore, it is preferable to smooth the surface of the sheet. For example, it is preferable to cool the extruded film in a molten state by pressing the film with a cast drum and an attached cooling roll, or a cast drum and a metal endless belt. At that time, not only the cast drum, but also the attached cooling roll or the surface of the metal endless belt must be smooth, that is, the maximum roughness of the cooling body surface must be as smooth as 0.2S or less. By cooling sufficiently, both sides of the film can be rapidly cooled to prevent crystallization.

As another method, the non-drum surface of the film cast on a smooth drum of 0.2 S or less may be pressure-bonded with an additional roll heated to a temperature equal to or higher than the glass transition, and rapidly cooled with a cooling roll.

Further, the extruded polymer in a molten state may be stored as a bank between two rolls having a smooth surface of 0.2 S or less and extruded from between the rolls for calendering.

Further, the extruded molten polymer is cast on a smooth metal endless belt of 0.2 S or less, heated and pressed with the smooth endless belt and another smooth metal endless belt, and rapidly cooled. You may.

To impart mechanical strength to the film, T
The unstretched sheet extruded from the die is preferably further biaxially stretched. In the case of biaxial stretching, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used, but a sequential biaxial stretching method in which stretching is performed first in the longitudinal direction and then in the width direction is preferable. In the case of performing successive biaxial stretching, streaks generated when extruded from the T-die are eliminated to a level that does not cause any problem, so that the above-described surface smoothing method may not be performed.

The stretching temperature is preferably in the range from the glass transition temperature to the cold crystallization temperature, but in the present invention, it is 60 to 140 ° C. in the longitudinal direction and 70 to 1 in the width direction.
Desirably, the temperature is 50 ° C. Stretching ratio is usually 2.0 to
A value of 5.0 is appropriate. In order to increase the strength of the film, it is better to increase the draw ratio within a range where the film formability is not reduced, preferably 3.5 times or more, particularly preferably 4.
0 times or more. After stretching in the vertical and horizontal directions, the film may be stretched in the vertical or horizontal direction again.

In order to improve the tear propagation resistance of the film, it is desirable to increase the stretching ratio to balance the longitudinal direction and the lateral direction, preferably at least 3.4 times.
Particularly preferably, it is 3.8 times or more, and the difference between the stretching ratio in the longitudinal direction and the transverse direction is preferably 0.7 or less, more preferably 0.5 or less.

Further, the stretched film may be subjected to a heat treatment. The heat treatment conditions in this case may be any of a constant length, a relaxed state, and a finely stretched state. In the case of the polyester film of the present invention, it is preferably 150 to 230 ° C.,
0.5 to 60 seconds in the range of 0 to 220 ° C is suitable.
In particular, in the case of the present invention, the heat treatment temperature is preferably higher within a range where the film-forming property is not reduced, whereby the heat shrinkage at 150 ° C. is reduced, and the curl recovery property can be further improved.

Particularly, in the case of the polyester film of the present invention, after being stretched at a high magnification, heat treatment is performed at a high temperature so that the breaking strength and the tear propagation resistance can be increased in a well-balanced manner, and further, the low heat shrinkage and the curl recovery are improved. The property is also good.

The thickness of the copolymerized polyester film of the present invention is not particularly limited.
~ 360 μm, 50 ~ 2000 for non-stretched film
μm is preferably used. In the case of a photographic film application field, the thickness is preferably from 25 to 250 µ, more preferably from 40 to 150 µ.

The polyester film of the present invention can be subjected to various surface treatments such as a corona discharge treatment, a chemical solution treatment and a flame treatment as needed in order to improve the adhesiveness and the wetting characteristics of the coating solution. In the present invention, corona discharge treatment is preferred.

When the polyester film of the present invention is used as a photographic light-sensitive material, an undercoat layer necessary for increasing the adhesive strength between the polyester film and a photographic layer such as a photosensitive layer provided thereon, Further, well-known materials may be used for providing a backing layer for imparting functions such as antistatic property, antihalation property, curl balance, slipperiness, and scratch resistance, and for coating an emulsion layer and the like.

The polyester film of the present invention can be used for various transparent films, for example, OHP films, by utilizing its excellent transparency, thermal dimensional stability, and mechanical properties in addition to the support or cover layer of the photographic light-sensitive material. It can be used for packaging films for optical films and fresh foods.

[0054]

[Method of measuring physical properties]

(1) Glass transition temperature, cold crystallization temperature Polyester film or polyester 10mg
Was set in a differential scanning calorimeter and the temperature was set to 20 ° C. under a nitrogen stream.
The temperature was raised at a rate of / min, and the average value of the temperature at which the baseline began to be biased and the temperature at which the baseline returned to a new baseline was taken as the glass transition temperature. The exothermic peak temperature accompanying crystallization was defined as the cold crystallization temperature.

(2) Film haze Film haze was measured according to ASTM-D1003-52.

(3) Moisture content After humidifying the polyester film at 23 ° C. and 30% RH for 3 hours, the polyester film is immersed in distilled water at 23 ° C. for 15 minutes. stock)
(Model CA-20) at a drying temperature of 150 ° C.

(4) Thermal Shrinkage A film sample having a width of 10 mm and a length of 250 to 300 mm is marked at intervals of 200 mm, fixed on a sample support plate under a constant tension, and used as a universal projector (Nippon Kogaku V16A).
Was used to measure the original length of the marking interval. A load is applied to the measured sample using a 3 g clip,
While rotating in a hot-air oven set to.
The treated sample was left for 2 hours in an atmosphere in which the original length was measured, and the shrinkage was determined by measuring the length of the marking interval in the same manner as in the original length measuring method.

(5) Tear Propagation Resistance Using a light load type tear tester (manufactured by Toyo Seiki Co., Ltd.),
It was measured according to ASTM-D-1922. The sample size is 51 x 64mm with a 13mm cut,
The indicated value when the remaining 51 mm was torn was read.

(6) Curling Curl Recovery Polyester film 35 mm in lateral direction, 13 mm in longitudinal direction
Sampling was performed to a size of 5 mm, wound around a core having a diameter of 10 mm, treated at 70 ° C., 30% RH for 72 hours, then released from the core, immersed in distilled water at 38 ° C. for 30 minutes, and then tensioned at 30 g. And dried in a hot air oven at 50 ° C. for 5 minutes. The diameter of the cylinder formed when the treated film sample was placed on a flat surface was measured. The curl curl recovery was evaluated on the following five levels. 5: The film did not curl and became flat 4: The cylinder diameter was 60 mm or more 3: The cylinder diameter was 40 to 60 mm 2: The cylinder diameter was 20 to 40 mm 1: The cylinder diameter was less than 20 mm (7) Breaking strength・ Young's modulus According to JIS-Z1702-1977, width 10 mm,
A strip having a length of 100 mm was measured at a tensile speed of 300 mm / min and an initial modulus of elasticity of 20 mm / min when measuring the breaking strength. The tensile Young's modulus at the time of water absorption was measured immediately after immersion in a strip at 25 ° C. for 30 minutes.

(8) Intrinsic viscosity Measured at 25 ° C. using an o-chlorophenol solvent.

[0061]

Next, the present invention will be described in more detail with reference to examples.

Example 1 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, 10 parts by weight of polyethyleneoxydicarboxylic acid having an average molecular weight of 4000 were mixed with 0.1 part of calcium acetate.
To the mixture were added 1 part by weight and 0.03 part by weight of antimony trioxide, and a transesterification reaction was carried out by a conventional method. 0.05 parts by weight of phosphoric acid trimethyl ester was added to the obtained product, and the temperature was gradually increased and the pressure was reduced.
Polymerization was performed at Hg or lower to obtain a copolymerized polyester A having an intrinsic viscosity IV of 0.9.

As the polyester B, the intrinsic viscosity IV = 0.
Using polyethylene terephthalate No. 7, 0.2% by weight of SiO ₂ having an average particle diameter of 0.1 μm was added as inert particles.

After drying the polyester by a conventional method, a biaxial stretching film-forming machine equipped with two extruders and a die capable of three-layer melt co-extrusion was used. Polyester B was supplied to an extruder, melted at 280 ° C., and co-extrusion of three B / A / B layers was performed to prepare an unstretched sheet. Then, at 80 ° C, 3.8 times in the vertical direction, 85 ° C
, And then heat-set at 210 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm.
The thickness of B / A / B was 5 μm / 90 μm / 5 μm.

Example 2 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, 5 parts by weight of polytetramethyleneoxydicarboxylic acid having an average molecular weight of 4000, and 5 parts by weight of dimethyl adipate Then, 0.1 parts by weight of calcium acetate and 0.03 parts by weight of antimony trioxide were added thereto to prepare a copolyester A having an intrinsic viscosity IV = 0.9 in the same manner as in Example 1.

Also, 0.1 part by weight of calcium acetate and 0.03 part by weight of antimony trioxide are added to 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, and 10 parts by weight of dimethyl 5-sodium sulfoisophthalate to form a unique product. A copolyester B having a viscosity IV = 0.75 was prepared.

In the same manner as in Example 1, B / A / B three-layer coextrusion was performed to form a sheet, and the sheet was elongated 3.6 times in the longitudinal direction at 85 ° C.
After successively stretching 4.0 times in the transverse direction at 0 ° C.,
This was heat-set for 2 seconds to obtain a biaxially stretched film having a thickness of 100 μm. The thickness of B / A / B was 5 μm / 90 μm / 5 μm.

Example 3 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, 5 parts by weight of polyethyleneoxydicarboxylic acid having an average molecular weight of 6000, and 5 parts by weight of polyethylene glycol having an average molecular weight of 1000 In the part, calcium acetate 0.1
Copolymer Polyester A was prepared by adding 0.1 parts by weight of SiO ₂ having an average particle diameter of 0.1 μm as inert particles by weight, 0.03 parts by weight of antimony trioxide and 0.1% by weight of inert particles.

As polyester B, intrinsic viscosity IV =
Example 1 using polyethylene terephthalate of 0.7
Using the same extruder and die and, sheeted by performing three-layer co-extrusion of A / B / A, 3 longitudinally further 85 ° C..
After sequentially stretching 4.0 times in the transverse direction at 6 times and 90 ° C.,
The film was heat-set at 0 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm. The thickness of A / B / A is 30 μm / 40 μm
/ 30 μm.

Example 4 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 8 parts by weight of dimethyl 5-sodium sulfoisophthalate, 10 parts by weight of polyethyleneoxydicarboxylic acid having an average molecular weight of 4000, 0.1 part by weight of calcium acetate And 0.03 parts by weight of antimony trioxide and 0.1% by weight of SiO ₂ having an average particle diameter of 0.1 μm as inert particles were added and copolymerized, and further subjected to solid-state polymerization in 210 ° C. degassing, Polyester A with intrinsic viscosity IV = 1.1
It was created.

Also, 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 1 part by weight of dimethyl 5-sodium sulfoisophthalate, an average molecular weight of 400
0 parts by weight of polyethylene oxydicarboxylic acid, 0.1 part by weight of calcium acetate and 0.0 part by weight of antimony trioxide.
By adding 3 parts by weight, a polyester B having an intrinsic viscosity IV = 0.7 was prepared.

A / B / A three-layer co-extrusion was performed using the same extruder and die as in Example 1 to form a sheet. 3. in the direction
After successively stretching 0 times, it was heat-set at 220 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm. The thickness of A / B / A was 25 μm / 50 μm / 25 μm.

Example 5 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, and 10 parts by weight of polyethylene oxydicarboxylic acid having an average molecular weight of 4000 were used as inert particles. 0.2% by weight of SiO ₂ having a particle diameter of 0.1 μm was added, and a copolyester A having an intrinsic viscosity IV = 0.85 was obtained in the same manner as in Example 1.

As the polyester B, the intrinsic viscosity IV = 0.
65 polyethylene terephthalate was used.

As polyester C, 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol,
To 0.1 part by weight of dimethyl sodium-sulfoisophthalate, 0.1 part by weight of calcium acetate and 0.03 part by weight of antimony trioxide were added to prepare a copolymerized polyester having an intrinsic viscosity IV of 0.75.

After drying the polyester by a conventional method, using a three-axis extruder and a biaxial stretching film-forming machine equipped with a die capable of five-layer co-extrusion, polyester A,
B and C were supplied and melted at 280 ° C., and C / A / B / A /
Five layers of C were co-extruded to prepare an unstretched sheet.
Next, the film was successively stretched 3.5 times in the longitudinal direction at 95 ° C. and 3.8 times in the transverse direction at 100 ° C., and then heat-set at 220 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm. C / A /
The thickness of B / A / C is 2 μm / 30 μm / 36 μm / 3
0 μm / 2 μm. The surface of the obtained film was further subjected to a corona discharge treatment.

COMPARATIVE EXAMPLE 1 A polyethylene terephthalate to which 0.1% by weight of SiO ₂ having an average particle diameter of 0.1 μm was added as an inert particle was prepared according to a conventional method, and an intrinsic viscosity IV was 0.65. 3.5 times in the vertical direction at, and 3 times in the horizontal direction at 95 ° C.
After successively stretching by 8 times, it was heat-set at 220 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm. Comparative Example 2 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, 10 parts by weight of polyethylene glycol having an average molecular weight of 4000, 0.1 part by weight of calcium acetate and 0 parts by weight of antimony trioxide 0.03 parts by weight was added to prepare a copolymerized polyester having an intrinsic viscosity IV of 0.80, and further formed into a sheet, and sequentially stretched 3.6 times in the longitudinal direction at 85 ° C and 4.0 times in the transverse direction at 90 ° C. After that, the film was heat-set at 200 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm.

Comparative Example 3 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate, 10 parts by weight of dimethyl adipate, 0.1 part by weight of calcium acetate and 0 parts by weight of antimony trioxide .
A copolymerized polyester having an intrinsic viscosity IV of 0.80 was prepared by adding 03 parts by weight, and further formed into a sheet, which was successively stretched 3.6 times in the longitudinal direction at 85 ° C. and 3.8 times in the transverse direction at 90 ° C. Thereafter, the film was heat-set at 200 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 100 μm.

Table 1 shows Examples 1 to 5, and Table 2 shows Comparative Examples 1 to 3.
And the physical properties of the TAC film. In Comparative Example 1, the water absorption was low, and no curl curl recovery was observed. In Comparative Example 2, the curl curl recoverability was relatively good, but the thermal dimensional stability was insufficient. In Comparative Example 3, both the curl recovery property and the thermal dimensional stability were insufficient, and a low polymer was precipitated due to aging, and the transparency was deteriorated. In contrast,
In Examples 1 to 5, films excellent in transparency, mechanical properties, thermal dimensional stability, curl curl recovery were obtained.
Even when aged at 0 ° C. and 90% RH, the haze value hardly changed and the transparency was maintained, and these films were useful as film supports for photographic light-sensitive materials and the like.

[0080]

[Table 1]

[Table 2]

[0081]

The polyester film of the present invention is a copolymerized polyester film having excellent transparency, water absorbency, mechanical properties and heat resistance. It is possible to make the film thinner than a TAC film, and it is possible to reduce the size and speed of unwinding of the photographing device. Further, due to its excellent thermal dimensional stability, it can be used for OHP sheets requiring heat resistance, and its good water absorption can be used, for example, for packaging films of fresh foods.

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Claims (8)

(57) [Claims] 1. A polyester film having a multilayer structure, wherein the dicarboxylic acid copolymerization component of the polyester A constituting at least one layer thereof is an aromatic dicarboxylic acid having a metal sulfonate and / or a derivative thereof;
(A) including a polyether dicarboxylic acid having an average molecular weight of 600 to 20,000 represented by the formula and / or a derivative thereof
Polyester film, said polyester film
The film is biaxially oriented, and the haze value of the film is 5% or less,
And the water content is 0.5% or more, at 150 ° C. for 30 minutes
A polyester film having a heat shrinkage of not more than 2% . _{^{R 1 OOCCH 2 - (O-}} R 2) n-OCH 2 COOR
³ (R ¹ , R ³ : H or an alkyl group having 1 to 8 carbon atoms, R
² : an alkylene group having 2 to 8 carbon atoms, n: a positive integer) 2. In polyester A, 2 to 20% by weight of an aromatic dicarboxylic acid having a metal sulfonate and / or a derivative thereof, and 2 to 2% by weight of a polyether dicarboxylic acid.
2. The polyester film according to claim 1, wherein the amount is 0% by weight. 3. The polyester film according to claim 1, wherein the polyether dicarboxylic acid is a polyethyleneoxydicarboxylic acid represented by the formula (b). _{^{R 1 OOCCH 2 - (O-}} CH 2 CH 2) n -OCH 2
COOR ² (b) (R ¹ , R ² : H or carbon number 1
To 8 alkyl groups, n: a positive integer) 4. Polyester B having a glass transition temperature of 60 ° C. or more is provided on at least one side of a layer made of polyester A.
The polyester film according to any one of claims 1 to 3, wherein the polyester film is formed by laminating layers. 5. The method according to claim 1, wherein a layer made of polyester A is laminated on both sides of a layer made of polyester B having a glass transition temperature of 60 ° C. or higher.
Item 4. The polyester film according to any one of items 3. 6. is a tear propagation resistance of the polyester film is 500 g / mm or more, polyester film according to any one of Claims first to fifth paragraphs, wherein the glass transition temperature of 50 ° C. or higher . 7. A polyester film according to any of claims No. 1-6 wherein the tensile Young's modulus immediately after immersion for 30 minutes a polyester film in water is equal to or is 280 kg / mm ² or more. 8. A photograph comprising the polyester film according to any one of claims 1 to 7 as a support and at least one photosensitive layer on the polyester film. Photosensitive material.