Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Reexamination Certificate
1999-11-10
2001-01-16
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
C430S523000, C430S533000, C428S331000, C428S480000, C524S493000
Reexamination Certificate
active
06174655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a biaxial oriented polyester film and a method of manufacturing the same, and to a photographic substrate and a photographic light-sensitive material using the biaxial oriented polyester film. The biaxial oriented polyester film is suitable for use in various applications, in particular as a photographic substrate.
2. Description of the Related Art
Polyester films have excellent physical and chemical characteristics and have been used in various fields. Among these polyester films, a biaxial oriented polyester film, which has been stretched longitudinally and transversely so as to have high strength, is excellent in electric characteristics, chemical resistance, mechanical characteristics, flatness, dimensional stability, and economic efficiency, and therefore has been used in a large number of fields such as photography, magnetic recording media, and packaging.
The biaxial oriented polyester film has a drawback in that the film is not as good in slidability as in flatness, and this drawback adversely affects handling of the film in the manufacturing and working processes. Moreover, when the biaxial oriented polyester film is used as a substrate for a magnetic recording medium such as a photographic film (i.e., a photographic light-sensitive material) or a magnetic tape, excellent slidability is required so as to ensure travelling stability of the film in a camera, a developing device, a magnetic recording/replaying device, or the like.
In order to respond to such a demand for improvement in slidability, there are proposed a method of adding inorganic fine particles such as silica or calcium carbonate to the biaxial oriented polyester film, and a method of depositing fine particles containing calcium, lithium or phosphorus in the polymeric system at the time of synthesis of the polyester. With these methods, when the biaxial oriented polyester film is formed, projections are formed on the surface of the film by fine particles, and slidability is thereby obtained. However, since various apparatuses have been miniaturized and made precise recently, further improvement in slidability is desired.
Increasing the particle diameter of the fine particles to be added and the amount of the fine particles used is effective for improving slidability. However, scratches may be formed on the surface of the film by a roll during stretching of the film in the longitudinal direction thereof. Therefore, considering the suitability thereof for the longitudinal stretching of the film, the use of fine particles having a small particle diameter is desired, and the use of an excess of fine particles must be avoided. Further, a high degree of transparency is required in a substrate for a photographic film (a photographic substrate). However, a problem arises in that the transparency of the film decreases when fine particles having a large particle diameter are used or a large amount of fine particles are used.
Namely, in the biaxial oriented polyester film, an improvement in slidability is traded off against an improvement in suitability for the longitudinal stretching of the film and in transparency. Therefore, a biaxial oriented polyester film satisfying all of these characteristics and a manufacturing method thereof have been desired.
Accordingly, an object of the present invention is to provide a biaxial oriented polyester film and a method of manufacturing the same, in which a sufficient suitability for the longitudinal stretching and a sufficient transparency are achieved while a high degree of slidability is ensured. Further, another object of the present invention is to provide a photographic substrate and a photographic light-sensitive material utilizing the biaxial oriented polyester film having the above-described excellent characteristics.
SUMMARY OF THE INVENTION
The above-described objects are achieved by the present invention described below.
<1> A biaxial oriented polyester film, comprising 0.001 to 0.05% by weight of spherical silica particles with a number average particle diameter (Xm) of 0.20 to 0.50 &mgr;m and a particle size distribution represented by the following formula (1):
0.1≦|
d
90
−Xm|/|d
10
−Xm
|≦0.7 (1)
wherein d
10
represents a particle diameter (&mgr;m) obtained when the number of the particles is summed from the particles with the smallest diameter toward the particles with larger diameters and the number reaches 10% of the total number of the particles, d
90
represents a particle diameter obtained in the same manner as for d
10
described above except that the particle diameter is obtained when the number of the particles reaches 90% of the total number of the particles, and Xm represents a number average particle diameter.
<2> A biaxial oriented polyester film according to <1>, wherein the average spherical ratio of the spherical silica particles is 1.0 to 1.2.
<3> A method of manufacturing a biaxial oriented polyester film of <1> or <2>, comprising: a low-molecular weight polymer forming step, in which low-molecular weight polymers of polyester containing the spherical silica particles are obtained by transesterification; a polymer forming step, in which polyester polymers are obtained by a polycondensation reaction of the low-molecular weight polymers of polyester; and an extruding and stretching step, in which the polyester polymers are melt extruded and biaxially stretched.
<4> A method of manufacturing a biaxial oriented polyester film according to <3>, wherein, in the low-molecular weight polymer forming step, the spherical silica particles are added to a reaction system before the transesterification substantially starts.
<5> A method of manufacturing a biaxial oriented polyester film according to <3>, wherein a filtration step, in which the low-molecular weight polymers of polyester are filtered with a filter, is carried out between the low-molecular weight polymer forming step and the polymer forming step.
<6> A method of manufacturing a biaxial oriented polyester film according to <5>, wherein the cutout rate of the filter with respect to standard particles with a particle diameter of 1 &mgr;m is 80% or more.
<7> A method of manufacturing a biaxial oriented polyester film according to <3>, wherein 5 to 40% by weight of the biaxial oriented polyester film of <1>, which has a limiting viscosity of 0.35 or more and has been shredded, is mixed with a lower alkyl ester of aromatic dicarboxylic acid, and the resulting mixture is, together with glycol, subjected to the transesterification carried out in the low-molecular weight polymer forming step.
<8> A photographic substrate formed from the biaxial oriented polyester film of <1>.
<9> A photographic substrate formed from a biaxial oriented polyester film which is manufactured with the method of manufacturing a biaxial oriented polyester film of <3>.
<10> A photographic light-sensitive material which has at least a light-sensitive layer formed on a substrate, wherein the substrate is the photographic substrate of <8>.
Since the biaxial oriented polyester film of the present invention described above uses the spherical silica particles having an appropriate number average particle diameter and an appropriate particle size distribution, sufficient suitability for the longitudinal stretching and transparency can be achieved while a high slidability is ensured. Specifically, the present invention provides a biaxial oriented polyester film with the above-described excellent characteristics by accommodating in the film spherical silica particles having a sufficient particle diameter to ensure a high slidability while preventing as much as possible the presence of spherical silica particles having a larger particle diameter which adversely affects the suitability thereof for longitudinal stretching and transparency, and by accommodating in the film
Shirokura Yukio
Suzuki Fumiyuki
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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