JP2875155B2 - Base film for photo film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base film for a photographic film, and more particularly, to a base film for a photographic film made of polyethylene naphthalate having excellent decurling properties, transparency, hue and delamination resistance. About.

[0002]

2. Description of the Related Art Photographic films include those used as sheet films such as X-ray films, plate making films, and cut films, and color films or black-and-white negative films used in general cameras for photographing. Some are used as roll films.

A biaxially stretched polyester film made of polyethylene terephthalate is mainly used as the base film of the sheet film, and triacetyl cellulose (hereinafter sometimes abbreviated as "TAC") is used as the base film of the roll film. A film composed of a representative cellulosic polymer is mainly used.

The characteristics of a TAC film are that it has no optical anisotropy, high transparency, and excellent curl-removing properties after development processing. In particular, curl-removing properties are not found in films of other materials. It is said to be a feature. However, since this TAC film uses an organic solvent in the manufacturing process, it is necessary to take care to completely recover the solvent and not to pollute the environment. In particular, recently, the problem of environmental destruction has attracted attention, and there has been a strong tendency to avoid using an organic solvent that may cause environmental pollution as much as possible.

On the other hand, without using such an organic solvent,
As a film that can be formed by a melt extrusion method, there is a polyethylene terephthalate film, which has come to be used as a base film of a photographic film used in the above-mentioned sheet film.

However, a polyethylene terephthalate film has a property that a curl (curl habit) remains strongly and it is difficult to remove the curl, so that the range of use for a photographic film is limited. For example, if a polyethylene terephthalate film is used as a roll film, the curl remains strongly on the film after the photo-developing process (the curl-removing property is poor). The film may be damaged or the focus may be out of focus.
For this reason, the polyethylene terephthalate film is difficult to use for a photographic film used as a roll film.

Various techniques have been proposed for improving the curl removability of the polyethylene terephthalate film.

For example, JP-A-1-244446 or JP-A-53-146773 discloses a modified polyethylene terephthalate having a water content of 0.5% by weight or more, or an aromatic containing polyethylene glycol or metal sulfonate. A photographic material using a modified polyethylene terephthalate copolymerized with a dicarboxylic acid for a base film is disclosed. However, although photographic films using these modified polyethylene terephthalates have the effect of decurling, the dimensional stability when absorbing moisture is deteriorated due to the increased water content, and aromatic films containing metal sulfonates The copolymer of aromatic dicarboxylic acid has disadvantages such as low glass transition temperature and increased deformation of the end face of the film, and is not sufficient for photographic films.

Further, Japanese Patent Application Laid-Open No. 50-16678,
JP-A-56-53754 discloses a technique for improving curl resolving properties, such as canceling out curl by a difference in shrinkage stress of each layer in a biaxially oriented polyester film in which polyesters having different intrinsic viscosities are laminated. . However, these improved techniques have disadvantages such as difficulty in adjusting the difference in contraction stress.

Further, as a polyester film having improved curl removability, for example, a biaxially oriented polyethylene terephthalate film or a polyethylene naphthalate film subjected to a heat treatment in US Pat. No. 4,141,735 is disclosed. It is difficult to obtain a base film for a photographic film which satisfies all of hue, delamination resistance and curl-removing property.

In recent years, the quality requirements for photographic films used as roll films have become more sophisticated. For example, photographic films that can be transported at a higher speed than before in photographing, and photographic devices that are smaller than in the past in order to reduce the size of the photographing apparatus. There is a demand for a photographic film or the like which is thin and can be used with a small winding diameter. Therefore, the base film for a photographic film is capable of withstanding higher-speed conveyance than before, has good curl removability when wound with a smaller winding diameter than before, and is mechanically thinner than before. Good strength and dimensional stability are required. A triacetate film, a modified polyethylene terephthalate film or a biaxially oriented polyethylene terephthalate film or a polyethylene naphthalate film which has been subjected to a heat treatment cannot sufficiently meet these demands, and a base film for a photographic film having excellent properties is desired. It is rare.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a base film for a photographic film which is excellent in transparency, hue, delamination resistance and curl removability.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
According to the present invention, there is provided a polyester film comprising a polyester containing polyethylene naphthalate as a main component, wherein the crystallinity of the film is 30% or more and less than 50%, the haze is 2.0% or less, and the yellow index (Y _ID ) Is 5 or less, and the acetaldehyde content is 60 ppm or less.

In the present invention, polyethylene naphthalate is a polyester containing naphthalenedicarboxylic acid as a main acid component and ethylene glycol as a main glycol component.

Examples of the naphthalenedicarboxylic acid component include 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid.
Examples thereof include naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid.
6-Naphthalenedicarboxylic acid is preferred because it becomes a polyethylene naphthalate for a base film having excellent properties. It is not preferable that the main acid component is not naphthalenedicarboxylic acid, for example, since the curl removability of the film becomes poor.

Other acid components include aromatic dicarboxylic acids (for example, terephthalic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfondicarboxylic acid, diphenylketonedicarboxylic acid, anthracenedicarboxylic acid, etc.). ); Aliphatic dicarboxylic acids (eg, adipic acid, sebacic acid, etc.); alicyclic dicarboxylic acids (eg, cyclohexane-1,4-dicarboxylic acid, etc.). The proportion of these acid components is preferably at most 20 mol%, more preferably at most 5 mol%, especially at most 2 mol%, based on the total acid components, for example, because the film can be better decurled. preferable.

Examples of the glycol component other than ethylene glycol include aliphatic glycols (for example, polymethylene glycol having 3 to 10 carbon atoms such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, etc.). Alicyclic glycols (eg, cyclohexane dimethanol); aromatic diols (eg, hydroquinone, resorcin, 2,2-bis (4-hydroxyphenyl) propane, etc.); polyoxyalkylene glycols (eg, diethylene glycol, triethylene glycol, polyethylene) Glycol, polypropylene glycol, polytetramethylene glycol, etc.). The proportion of these glycol components is preferably at most 20 mol%, more preferably at most 5 mol%, especially at most 2 mol%, based on the total glycol components, for example, in order to improve the curl removability of the film. preferable.

In the polyethylene naphthalate of the present invention, an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid and an aliphatic oxyacid such as ω-hydroxycaproic acid may be used within a range not to impair the effects of the present invention. Can be copolymerized in an amount of 20 mol% or less based on the total acid components.

The polyethylene naphthalate in the present invention is a substantially linear polyester. However, as long as the effects of the present invention are not impaired, for example, an amount of 2 mol% or less based on the total acid component is a trifunctional or higher polycarboxylic acid. Acids or polyhydroxy compounds such as trimellitic acid, pentaerythritol and the like can also be copolymerized.

Further, the polyethylene naphthalate of the present invention may contain, for example, a lubricant, a pigment, a dye, an antioxidant, and a light stabilizer as long as the transparency, surface flatness and thermal stability of the polyester film are not impaired. Additives such as light-shielding agents (for example, silica, cross-linked polystyrene, terazole blue, Irganox, cobalt, etc.) can also be added as necessary.

The polyethylene naphthalate in the present invention can be produced by polycondensing the above-mentioned acid component containing naphthalenedicarboxylic acid and / or its lower alkyl ester as a main component and a glycol component containing ethylene glycol as a main component. However, in particular, it can be produced by polycondensation of a reaction product obtained by transesterification of an acid component mainly containing a lower alkyl ester of naphthalenedicarboxylic acid and a glycol component mainly containing ethylene glycol, This is preferable because a film having good hue and good transparency can be obtained.

Examples of the lower alkyl ester of naphthalenedicarboxylic acid include dimethyl ester, diethyl ester, dipropyl ester and the like, and dimethyl ester is particularly preferred.

The polyester film of the present invention has a crystallinity of 30% or more and less than 50%, and preferably 35% or more and less than 45%. If the crystallinity exceeds 50%, the transparency of the film becomes insufficient and the curl resolving property is deteriorated.
%, It is not preferable as a base film for a photographic film because the delamination resistance of the film becomes poor.

The above-mentioned delamination resistance (hereinafter, sometimes referred to as “delamination characteristics”) of the polyester film can be specified by measuring the fold delamination whitening ratio. The fold delamination whitening ratio is preferably 10% or less, and if it exceeds 10%, the film is liable to peel off (delamid),
It is not preferable because it causes problems such as whitening of the delaminated portion, easy delamination during perforation hole formation, and easy growth of scratches caused by contact with metal or the like.

The polyester film of the present invention having a degree of crystallinity of 30% or more and less than 50% can be obtained, for example, by appropriately setting the stretching and heat setting conditions in the production of the film.

The haze of the polyester film of the present invention is 2.0% or less, preferably 1.5% or less, more preferably 1.0% or less. If the haze exceeds 2.0%, the transparency of the film is undesirably reduced.

The yellow index (Y _ID ) of the polyester film of the present invention is 5 or less. Y _ID is 5
Exceeding the range is not preferable because the image has an uneven color tone when used for a color photographic film.

Further, in the present invention, the content of acetaldehyde (hereinafter sometimes abbreviated as "AA") in the polyester film is 60 ppm or less, preferably 50 ppm or less.
pm or less, more preferably 40 ppm or less. When the AA content exceeds 60 ppm, not only does the hue of the film deteriorate, but also when used as a base film for a photographic film, the photosensitive agent coated on the surface of the base film is denatured, resulting in a biased color tone. Not preferred.

In order to obtain a polyester film having an AA content of 60 ppm or less according to the present invention, for example, when melt polymerizing polyethylene naphthalate, 2 to 2 parts of naphthalenedicarboxylic acid and / or a lower alkyl ester thereof are used.
0 mmol% alkali metal salt and 1-50 mmol% quaternary ammonium salt were added and blended, and polyethylene naphthalate obtained by suppressing the amount of AA production was used in the production of films, and was obtained by melt polymerization. Polyethylene naphthalate under reduced pressure or nitrogen gas flow
A method of using a polyethylene naphthalate having a low AA content obtained by solid-phase polymerization at a temperature of 90 ° C. or higher and 10 ° C. lower than the melting point for the production of a film, and a polyethylene naphthalate film obtained by biaxially stretching the film. And (Tg
(+60) ° C. to (Tg + 120) ° C. (Tg: glass transition temperature of polyethylene naphthalate), a method of heat setting under a nitrogen gas stream under the condition that the crystallinity of the film is in the range of 30 to 50%. Can be mentioned.

The polyethylene naphthalate film of the present invention is not particularly limited by the production method, and can be preferably produced, for example, by the following method. For example, polyethylene naphthalate is melted at a temperature of (Tm + 10) ° C. to (Tm + 30) ° C. (where Tm is the melting point of polyethylene naphthalate), extruded into a sheet, and cooled by a cooling drum to obtain an unstretched film. Next, the unstretched film is uniaxially (vertically or horizontally) (T
g-10) ° C. to (Tg + 50) ° C. (however, T
g is the glass transition temperature of polyethylene naphthalate) and 2
(Tg) to (Tg + 50) ° C. in a direction perpendicular to the upward stretching direction (when the first-stage stretching is in the longitudinal direction, the second-stage stretching is in the transverse direction). 2-5 at temperature
The target polyethylene naphthalate film can be produced by stretching at twice the magnification and then heat-setting at a temperature of 60 ° C. or more and 120 ° C. or less than Tg and, if necessary, a heat relaxation treatment. At that time, properties such as surface characteristics, density, and heat shrinkage of the film vary depending on stretching conditions and other manufacturing conditions, so that conditions can be appropriately selected as needed.

If the heat setting temperature is lower than Tg + 60 ° C., the whitening rate of the fold delamination of the film becomes unfavorable. On the other hand, if the heat setting temperature is higher than Tg + 120 ° C., the film is whitened due to excessive crystallization of polyethylene naphthalate, and the transparency becomes poor, which is not preferable. The obtained film can be heat-treated at a temperature of 60 ° C. or more and 120 ° C. or less than the Tg of the polyethylene naphthalate in order to further improve the decurling property.

The thickness of the polyester film of the present invention can be appropriately selected depending on the use of the photographic film used as the base film, but is preferably 25 to 250 μm, particularly preferably 40 to 150 μm.

The polyethylene naphthalate film of the present invention can be provided with lubricity according to the application.
Means for imparting lubricity are not particularly limited, and a general method such as a method of dispersing lubricant particles in a polymer or a method of providing a layer having lubricity on a film surface may be used. it can.

The method of dispersing the lubricant particles in the polymer includes a method of adding SiO ₂ , BaSO ₄ , CaCO ₃ , alumina silicate, crosslinked organic particles and the like to the polymer,
A method of precipitating a catalyst or the like during the polymerization of polyethylene naphthalate is exemplified. Of these, the method of adding lubricant particles to the polymer is preferable because the effect of imparting lubricity is remarkable. In particular, lubricant particles having a refractive index close to that of polyethylene naphthalate, for example, BaSO ₄ ,
A method of adding alumina silicate and crosslinked organic particles (such as crosslinked polystyrene) is preferred because it can impart lubricity and can maintain good transparency of the film.

In the method of providing a layer having lubricity on the surface of the film, a method of thinly laminating a layer having lubricating particles on at least one surface of a polyethylene naphthalate film substantially containing no lubricating particles is used. This is preferable in order to obtain a film having good transparency, and a method of co-extrusion by combining a plurality of extruders with a feed block or a multi-manifold can be cited as an effective means.

[0036]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples without departing from the gist thereof. In addition, each characteristic value in an Example was measured by the following method. In the examples, “parts” means “parts by weight”.

(1) Acetaldehyde (AA) concentration A polyethylene naphthalate film is pulverized into fine powder in liquid nitrogen, and the powder is sealed in a glass insert of a high-sensitivity gas chromatograph and captured at a temperature of 170 ° C. for 10 minutes. The acetaldehyde used is quantified.

(2) Film Haze (Transparency) According to JIS-K6714, the total haze value (%) per film is measured by an integrating sphere type HTR meter manufactured by Nippon Seimitsu Kogaku Co., Ltd. This haze is used as an index indicating the transparency of the film.

(3) Crease Delamination Whitening Ratio (Delamination Resistance) A film sample is cut out into a size of 80 mm × 80 mm, and while being folded lightly by hand, sandwiched between a pair of flat metal plates and then pressed by a press machine. Predetermined pressure P ₁ (kg / c
m ² G) for 20 seconds. After pressing, the folded film sample is returned to the original state by hand, pressed between the metal plates at a pressure P ₁ (kg / cm ² G) for 20 seconds. Thereafter, the film sample is taken out, the length (mm) of the whitened portion appearing on the fold is measured and totaled.
Using a new film sample, the above measurement is repeated with a press pressure of P ₁ = 1, 2, 3, 4, 5, 6 (kg / cm ² G). The average value of the total length (mm) of the whitened portion at each pressing pressure is the total length of the fold (8
0 mm) is defined as the fold delamination whitening ratio (%), and this value is used as the delamination of the film (delamination).
Is used as an index indicating the difficulty of occurrence (delamination resistance).

[0040]

(Equation 1)

(4) Yellow Index (Y _ID ) Using a color difference meter SZ- # 90 manufactured by Nippon Denshoku Industries Co., Ltd., the yellow index (Y _ID ) of the film is obtained by the following equation.

[0042]

(Equation 2)

Where X, Y and Z are tristimulus values of light determined by the International Commission on Illumination.

(5) Curl recovery rate (curl elimination property) A film sample having a size of 120 mm × 25 mm was adjusted in an atmosphere of 23 ° C. × 50% RH for 24 hours in a flat state, and then placed on a core having a diameter of 7 mm. Temporarily fix it so that it does not unwind, and heat-treat at 80 ° C for 2 hours, and then release from the core. Next, the sample was immersed in distilled water at 40 ° C. for 15 minutes, and the sample was suspended vertically in the longitudinal direction.
Dry for 3 minutes in a 55 ° C. air oven under a load of 3.5 g. Subsequently, the distance (A: mm) between the upper end and the lower end of the film is obtained except for the load. The curl recovery rate (%) (sometimes referred to as “curl recoverability”) is represented by the following formula and used as an index indicating curl resolvability.

[0045]

(Equation 3)

(6) Crystallinity The density of the polyester film was measured with a density gradient tube, and the crystallinity was determined from the following equation.

[0047]

(Equation 4)

In the formula, ρ: density of a polyester film sample ρa: 1.325 (perfect amorphous density of polyethylene nalephthalate) ρc: 1.407 (perfect crystal density of polyethylene nalephthalate) The unit is g / cm ^3.

Example 1 100 parts of 2,6-naphthalenedicarboxylic acid methyl ester and ethylene glycol 60
Was subjected to a transesterification reaction using 0.03 part (1.23 mol) of manganese acetate tetrahydrate as a transesterification catalyst, followed by trimethyl phosphate 0.1%.
023 parts (1.64 mol) were added to substantially terminate the transesterification reaction. At this point, 2 mmol% of hydroxytetraethylammonium was added to the acid component.

Further, after adding 0.024 parts (0.82 mol) of antimony trioxide, a polycondensation reaction was carried out by a conventional method under a high temperature and high vacuum, and an intrinsic viscosity (35% with a phenol / tetrachloroethane mixed solvent). 0.62)
dl / g of polyethylene naphthalate was obtained.

The polyethylene naphthalate pellets were dried at 180 ° C. for 5 hours, and then supplied to an extruder hopper.
Melted at a melting temperature of 300 ° C.
Through a slit die on a rotary cooling drum having a surface temperature of 40 ° C. to obtain an unstretched film. The unstretched film thus obtained is preheated at 120 ° C., further heated by a single IR heater having a surface temperature of 900 ° C. from 15 mm above between low-speed and high-speed rolls and stretched 3.0 times. Then, it was supplied to a stenter and stretched 3.3 times in the transverse direction at 140 ° C. The obtained biaxially oriented film was
At a temperature of 5 ° C., heat-fixed for 10 seconds under a nitrogen stream to a thickness of 75
A μm polyethylene naphthalate film was obtained. The intrinsic viscosity of this film was 0.60 dl / g.

The obtained film was heat-treated at 115 ° C. for 2 days, and the film characteristics were measured. As shown in Table 1, the results were good.

Example 2 A film was obtained under the same conditions as in Example 1 except that the heat setting of the film was performed at a temperature of 235 ° C., and a film was obtained. As shown in Table 1, a base film for a photographic film was used. And showed good characteristics.

Example 3 A film was obtained under the same conditions as in Example 1 except that the heat setting of the film was performed at a temperature of 185 ° C., and a film was obtained. Good characteristics were exhibited as a base film for photographic films.

Comparative Example 1 At the end of the transesterification reaction, no hydroxytetraethylammonium was added,
The film was obtained under the same conditions as in Example 2 to obtain a film.
As shown in Table 1, the AA concentration exceeded 60 ppm,
Further, the characteristics of the other films were also poor, and the characteristics required as a base film for photographic films could not be satisfied.

[0056]

[Table 1]

[0057]

The polyester film comprising the polyethylene naphthalate of the present invention has excellent transparency, hue, delamination resistance and curl-removing properties. For example, a film for photography, a roll film for still photography, and a roll film for movies. It can be used as a base film for a wide range of photographic applications such as a roll film for X-rays and a film for plate making.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-303167 (JP, A) JP-A-50-81325 (JP, A) JP-A-6-57019 (JP, A) JP-A-6-57019 202279 (JP, A) JP-A-5-257234 (JP, A) JP-A-6-19046 (JP, A) JP-A-7-120890 (JP, A) JP-A-6-116378 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G03C 1/795 G03C 1/81 C08G 63/189

Claims (1)

(57) [Claims] 1. A polyester film comprising a polyester containing polyethylene naphthalate as a main component, wherein the film has a crystallinity of 30% or more and less than 50%, a haze of 2.0% or less, and a yellow index (Y _ID ). A base film for photographic films, wherein the base film has an acetaldehyde content of 60 ppm or less.