JPS623414B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an oriented polyester film for photosensitive recording media. More specifically, the present invention relates to an oriented polyester film for photosensitive recording materials, particularly microfilms, which has excellent transparency and excellent workability. Polyester films, such as polyethylene terephthalate films, are widely used in various applications including information recording and electrical applications due to their excellent mechanical properties, heat resistance, and electrical properties. One of the uses of such polyester film is microfilm, which is a photosensitive recording material, and EVR.
(Electronic Video Recording) film,
It is used as a base for OHP (overhead projector) films, etc. As a base for a microfilm, in order to record and retrieve information, it is important that the base film has high transparency and that protrusions on the film surface that cause light scattering and transmission obstruction are small. If the transparency is low, the background of an enlarged image or printed image when used as a microfilm becomes cloudy or colored, and the sharpness of the image decreases. Furthermore, if there are tall protrusions on the film surface, this may cause scattering of light or obstruction of light transmission, making it impossible to record or take out that portion. Microfilms generally include silver salt films, diazo films, and carver films, with diazo films being the most commonly used. This diazo film has a diazonium salt emulsion, has a spectral sensitivity in the wavelength range of 350 to 400 nm, and is exposed to light in this wavelength range, that is, ultraviolet light, but it is different from the original microfilm (usually silver salt microfilm). When printing by printing on diazo film, if the light transmittance of the base film of the original microfilm is low in the 350 to 400 nm range, the amount of exposure to the diazo film will be insufficient, so the line drawing and background of the printed diazo microfilm will be The contrast of the image will be reduced, and the image quality will also be reduced. In such cases, the problem may be solved by increasing the exposure amount, but this is not a preferable solution because fine line drawings tend to disappear and the microfilm tends to deteriorate due to strong ultraviolet light. Also, when printing diazo microfilm over many generations,
If the base film of the diazo microfilm, which is the original for each generation, has low light transmittance in the 350 to 400 nm range, the image quality will deteriorate significantly. Culver film also has a spectral sensitivity in the ultraviolet region of 340 to 440 nm.
If the base film of the original microfilm has low light transmittance in the ultraviolet region, the image quality of the printed Culver microfilm will deteriorate. For these reasons, the base film of the microfilm is required to have high light transmittance in the ultraviolet region. Light transmittance in the ultraviolet region is 350nm
It can be evaluated from the transmittance at the wavelength of In addition, if there are large protrusions on the surface of the base film or large particles inside, the ultraviolet rays will be scattered, which will widen the line drawing width of the printed diazo microfilm and make the line drawing blurry.
Deterioration of image quality occurs. Furthermore, when projecting microfilm using a visible light source such as a projector or reader, the brightness of the image is an important factor. The problem is the light transmittance of the area, and if it is low, the brightness of the image will be reduced. Therefore, if there are large protrusions on the surface of the base film or large particles inside, the light transmittance in the visible range will decrease and the brightness of the image will decrease. In other words, the base film is required to have high light transmittance in the visible range;
Can be evaluated at 550nm. On the other hand, in order to handle the base film and the product film, it is necessary that the film has good slipperiness and excellent workability, that is, the coefficient of friction between films, films and metal rolls, etc. is small. If the slipperiness is poor, wrinkles may occur during manufacturing or handling of the base film or product film, and scratches may occur due to frictional wear, resulting in a product with many defects as an optical recording material. In addition, films with poor slip properties tend to stick to each other and develop (blocking), making them difficult to handle. In order to improve the slipperiness of a film, it is sufficient to provide unevenness to the film surface. For this purpose, for example, inert inorganic compound particles may be added to the polymer used as the film raw material, or inert catalyst residue may be added to the film surface. There are known methods in which the surface of a smooth film is roughened mechanically or chemically. However, on the other hand, an improvement in slipperiness usually results in a deterioration in transparency. As described above, the optical properties and workability (surface sliding properties) required of a base film for photosensitive recording media are contradictory, and it is difficult to satisfy both at the same time. As a result of intensive research into polyester films having both of these characteristics, the present inventors have discovered that a film that satisfies a specific range of surface roughness and light transmittance has excellent optical properties and workability at the same time. This is what led to the discovery of the present invention. That is, the present invention provides a polyester film having at least one surface roughened, and a PV value [y (unit/μ)] indicating the surface roughness of the rough surface and a CLA value [x (unit/μ)]. ] is in a range that simultaneously satisfies 5x+0.03≦y≦5x+0.25 and 0.003≦x≦0.0135, and the light transmittance at 350 nm is 68% or more and the light transmittance at 550 nm is 83% or more. This is an oriented polyester film for photosensitive recording material characterized by the following. The rough surface referred to in the present invention refers to the front and back surfaces of the film.
A rougher surface is defined as a rough surface. Therefore, only the rougher surface satisfies the surface roughness range specified in the claims, and the other surfaces satisfy the surface roughness range specified in the claims. In any case, the surface roughness may be equal to or smoother than that of the rough surface. The lower limit of the smooth surface is not particularly limited, but is usually 0.03μ for PV and 0.0025μ for CLA.
That's about it. The polyester referred to in the present invention refers to a polymer composed of an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, etc. and a glycol such as ethylene glycol, diethylene glycol, tetramethylene glycol, neopentylene glycol, etc. It is a polymer that can be obtained by condensation. The polyester is a polymer that can be obtained by directly polycondensing an aromatic dicarboxylic acid and a glycol. The polyester can be obtained by direct polycondensation of aromatic dicarboxylic acid and glycol, or by polycondensation after transesterification of aromatic dicarboxylic acid dialkyl ester and glycol, or by polycondensation of aromatic dicarboxylic acid dialkyl ester and glycol. It can also be obtained by methods such as polycondensation.
Typical examples of such polymers include polyethylene terephthanate and polyethylene-2,6-naphthalene dicarboxylate. The polymer may be a non-copolymerized homopolymer, and up to 15 mol% of the dicarboxylic acid component is a non-aromatic dicarboxylic acid component and/or up to 15 mol% of the diol component is a non-aliphatic glycol. It may also be a copolymerized polyester that is a diol component. Alternatively, it may be a polymer blend of the polyester and another polymer. Furthermore, the polyester may optionally have stability,
It may also contain additives such as colorants and antioxidants. By adapting raw material characteristics, film forming conditions, etc. so that the PV value and CLA value fall within the range specified by the present invention, light transmittance in the ultraviolet and visible regions is high, transparency is excellent, and workability is achieved. An excellent film can be obtained. The level of light transmittance of the microfilm in the ultraviolet region and the visible region, and the workability largely depend on the surface condition of the base film (film surface roughness). Transparency is high and good when the PV value (y) and CLA value (x), which indicate surface roughness, are in the range y≦0.265 (x<0.003) y<5x+0.03 (0.003≦x≦0.0135). The slipperiness is extremely poor, and blocking occurs when the films are stacked on top of each other, resulting in poor handling and workability. The range of y>0.265 (x<0.003) y>5x+0.03 (0.003≦x≦0.0135) y>0.3175 (x>0.0135) has good handling workability, but the transparency as a photosensitive recording medium is poor. . Films in the range of y≦0.3175 (x>0.0135) are inferior in handling workability and transparency. Therefore, a film that simultaneously satisfies the following two equations within the range defined by the present invention: 5x+0.03≦y≦5x+0.25 0.003≦x≦0.0135 has excellent transparency, good slipperiness, and blocking between films. It has excellent handling and workability. Preferably, the polyester film satisfies the following two equations: 5x+0.06≦y≦5x+0.21 0.004≦x≦0.012. More preferably, a material that simultaneously satisfies the following two equations: 5x+0.07≦y≦5x+0.19 0.006≦x≦0.011 has excellent transparency.
Moreover, it is most preferable because of its excellent handling and workability. At this time, a film that has a surface roughness within the range specified by the present invention and has a light transmittance of 68% or more at a wavelength of 350 nm and a light transmittance of 83% or more at a wavelength of 550 nm is , has high light transmittance in the ultraviolet and visible regions, and when this film is used as an original microfilm and is printed on diazo film or Culver film with ultraviolet light, the image is particularly clear.
Furthermore, there is very little deterioration in image quality even when printing is repeated for many generations with the diazo film made of the base film of the present invention, and the image projected with visible light from a projector is very bright, making it a perfect base for microfilm. It becomes an excellent film. Light transmittance for wavelength of 350nm is preferably 73%
The above is preferable, and more preferably 75% or more is particularly good for microfilm. On the other hand, the light transmittance at a wavelength of 550 nm is preferably
The film has excellent transparency of 85% or more, more preferably 88% or more. The upper limit of the light transmittance at a wavelength of 350 nm is not particularly limited, but is usually 85% or less. Also, 550n
The upper limit of the light transmittance of m is not particularly limited, but is usually 95% or less. The thickness of the film having surface roughness and light transmittance within the range specified by the present invention is not particularly limited, but a film of 50 to 250μ has mechanical strength and stiffness suitable for use as a microfilm. , transparency, and ease of handling. It is particularly desirable that the film has a thickness of 60 to 188μ. Although the method for producing the polyester film of the present invention is arbitrary, for example, the CLA value can be adjusted by adjusting the representative particle size of the added inert inorganic compound or a combination of large and small representative particle sizes and the amount added. PV
Since the value indicates the maximum, peaks, and valleys of the film's rough surface, it can be adjusted by the representative particle size of the added inert inorganic compound. The representative particle size range of the added inert inorganic compound of the present invention is 0.1 to 2.0μ, preferably 0.15 to 1.0μ, and the range of the amount added is
0.001-0.150% by weight, preferably 0.005-0.080
Weight%. A specific manufacturing method for the polyester oriented film will be explained. For example, a method in which several types of inert inorganic compounds with different particle size distributions are added to make them exist in the film; a method in which a phosphorus component is added during polymerization to generate a particle source, and at the same time, classified inorganic particles are added to make them exist in the film. Furthermore, a method in which a phosphorus component or other necessary additives are added during polymerization, a method in which an inactive compound is added, and a method in which the two are blended is preferably used. When inert additive particles are added to the polyester of the film material in the present invention, they may be added before polyester polymerization, during the polymerization reaction, or they may be kneaded in an extruder when pelletizing after polymerization. Further, it may be added during melt extrusion into a sheet form, dispersed in an extruder, and extruded, but it is preferable to add it before polymerization from the viewpoint of dispersibility. The polyester film that is the object of the present invention is a film that is oriented in at least one axis (therefore, it may be uniaxially oriented or biaxially oriented). Although the stretching ratio is not particularly limited, it is preferable that the film be stretched at a stretching ratio of 2.5 to 5.5 times in at least one direction, either vertically or horizontally. Particularly preferred are those oriented in biaxial directions. In a biaxially oriented film, the stretching ratios in the two axial directions may be equal, the longitudinal direction may be greater than the transverse direction, or the transverse direction may be greater than the longitudinal direction. Further, the film may be a single film or a laminated film. For example, the biaxially oriented polyester film of the present invention can be used at a normal extrusion temperature, that is, the melting point (Tm
An unstretched polyester film with an intrinsic viscosity (η) of 0.35 to 1.0 melt-extruded at a temperature of 0.35 to 1.0 (expressed as Tg) or higher (expressed as Tg) or lower (Tg + 70℃) or lower Stretch at a stretching ratio of (2.5 to 5.5) times in the longitudinal or transverse direction at temperature, and then in a direction perpendicular to the stretching direction (if the stretching direction is the longitudinal direction, then in the lateral direction) Tg ~ (Tg + 70°C) By stretching at a stretching ratio of (2.5 to 5.5) times (stretching may be such sequential biaxial stretching or simultaneous biaxial stretching; the manufacturing method is not particularly limited). The biaxially oriented film thus obtained is usually heat-set for 1 to 100 seconds at a temperature above (Tg + 70°C) and below Tm. It has high transparency, good slip properties, and excellent handling workability, making it the most suitable for photosensitive recording films, especially micro films, VTR films, EVR films, OHP films, etc. The method of measuring and evaluating the main characteristics in the present invention is shown below. (1) Surface roughness
Peak-to-Valley value and
CLA (Center Line Average) values are measured by the following methods. PV value: Using a stylus type surface roughness tester (SURFOOM 3B) manufactured by Tokyo Seimitsu Co., Ltd., measure the film surface with a needle radius of 3 μ and a load of 0.1 g. times,
Magnify the surface roughness direction by 20,000 times, apply a chart, and extract the reference length from the cross-sectional curve. Among the straight lines parallel to the average line, select the first peak from the highest and the first peak from the deepest. Select the line that passes through the valley bottom, divide the distance between these two lines by the roughness magnification, express the value in microns, and calculate this value.
Expressed as the average value of 10 PV values. CLA value: Pick out a part of measurement length L from the film surface roughness curve in the direction of its center line, set the center line of this cut out part as the X axis, and the vertical magnification direction as the Y axis, and calculate the roughness curve Y = f When expressed as (x), the value given by the following formula is expressed in μ units. R _CLA = 1/L∫ ^L _O |f(x)|dx In this measurement, eight measurements were made with a reference length of 0.25 mm, and the average value of the five measurements excluding the three with the largest value is expressed. (2) Light transmittance Using a multi-purpose self-recording spectrophotometer (MPS-5000) manufactured by Shimadzu Corporation, 210
The spectral transmittance for wavelengths of ~800 nm is written on a chart, and the spectral transmittances for wavelengths of 350 nm and 550 nm are read from the chart, and the light transmittance for each wavelength is expressed as a percentage (%). (3) Representative particle size Using the Shimadzu automatic sedimentation balance, use the Stokes equation T = 18ηh/G (ρ _p −ρ _p )×d ² [where, T: sedimentation time (sec), η: medium Viscosity (g/cm・sec=poise) h: Sedimentation distance (cm) G: Acceleration of gravity (980cm/sec ² ) ρ _p : Density of inert substance (g/cm ³ ) ρ _p : Density of medium (g / ^cm3 ) d: Particle size of inert substance (diameter/cm)] Calculate the sedimentation time corresponding to each particle size, and calculate the settling time for each particle size range (for example, 0.25μ or less,
0.5≧d＞0.25, 0.75≧d＞0.5 and 1.0≧d＞
0.75, etc.), find the weight of the inert substance within that sedimentation time range, express the proportion to the total weight of the inert substance as a percentage, and use this composition ratio as the grain size. Accumulated in order from the largest diameter to the smallest diameter (100 for particle size Oμ)
%) is prepared, and the particle size shown at an integration rate of 50% is defined as the representative particle size (μ). (4) Evaluation of image quality A diazo photosensitive solution having the following composition was applied to the base film and dried at a temperature of 90°C for 1 minute to obtain a diazo film with a coating thickness of 10 μm. N・N-diethylaminobenzenediazonium boron tetrafluoride salt 26.3g 2・2′・4・4′-tetrahydroxydiphenyl sulfide 7.4g 2-hydroxy-3-naphthoic acid-2′-methylanilide 19.6g citric acid Acid 23g Zinc chloride 1g Thiourea 2g Cellulose acetate butyrate 100g Methyl ethyl ketone 650g Ethyl acetate 650g This diazo film was adhered to the original commercially available silver salt microfilm, exposed with a high-pressure mercury lamp, and developed with ammonia gas to create a diazo microfilm. This was enlarged 300 times using a projector, the projected image was observed, and the quality of the image was evaluated using the following three levels. 1. A film particularly suitable for use with microfilms, with clear line drawings, no microscopic spots caused by the base film, and extremely bright images. 2. Although some small dark spots due to the base film were observed, the line drawing was not blurred, the image was bright, and there was no problem in practical use as a micro film. 3 A film with many dark shadow-like spots due to high protrusions on the surface of the base film or internal particles, resulting in dark images and blurred line drawings, which is a serious problem in practical use as a microfilm. (5) Static friction coefficient μS The value was measured when the front surface of the film and the back surface of the film were overlapped and rubbed by the method according to ASTMD-1894-63. (6) Workability A film with good slipperiness is easy to handle and therefore has excellent workability. On the other hand, a film with poor slip properties is difficult to handle and therefore has poor workability. Based on such criteria, the difficulty of workability was divided into ranks 1 to 4 below and evaluated. 1. Good workability: A film with a static friction coefficient μS of less than 0.5 and good slipperiness, so that it has good winding properties during film work and good handling properties afterwards. 2. No problems with workability: A film with a static friction coefficient μS of 05 or more and less than 1.0, which can be wound without any problems during the winding process during film work, and with no particular problems in subsequent handling. 3. Poor workability: The static friction coefficient μS is 1.0 or more, and the film can be wound well during the winding process, but scratches easily appear on the surface and the film is difficult to handle afterwards. 4. Very poor workability: During the winding process during film production, blocking occurs between the films, resulting in wrinkles or polygonal shapes, making it impossible to wind the film normally. (7) Overall evaluation: ◎: A film with high light transmittance in the ultraviolet and visible regions, good transparency, and good workability; ○: a film with no practical problems; ○: a film with high light transmittance in the ultraviolet and visible regions, good transparency, and good workability The transmittance is low and the transparency is poor.
Alternatively, a film with extremely poor workability and unusable was evaluated as "x". Examples 1 to 4, Comparative Examples 1 to 3 To dimethyl terephthalate, 40 mmol % of manganese acetate, 20 mmol % of antimony trioxide, and 40 mmol % of phosphorous acid were added as catalysts to carry out a transesterification reaction, and then transesterification was carried out as specified in the present invention. A predetermined amount of inert additive particles (see Table 1) is added to cause a polycondensation reaction so that [η] is within the range of 0.65.
Polyethylene terephthalate (value measured at 25°C using O-chlorophenol as a solvent) was obtained. This polyethylene terephthalate was dried at 160°C, melt-extruded at 280°C, and rapidly solidified on a casting drum kept at 40°C.
An unstretched film of 1250μ was obtained. The unstretched film was sequentially biaxially stretched at a longitudinal stretching temperature of 95°C, a longitudinal stretching ratio of 3.05 times, a transverse stretching temperature of 120°C, and a transverse stretching ratio of 3.3 times, and was heat-set at 210°C for 20 seconds to determine the thickness.
A 125μ film was obtained. For comparison, a film having a surface roughness outside the range defined by the present invention was prepared using the same method, and the results are also shown in Table 1.

[Table] In Comparative Example 1, it was very difficult to wind up the film during production because of its poor slipperiness. That is, blocking occurred between the films during winding, and the end faces began to shift. This shift eventually returned to its original position, but at this time a large wrinkle appeared. The rolled film roll had a polygonal shape and had no commercial value. Although this film had very high light transmittance in the ultraviolet and visible regions and good transparency, the static friction coefficient μS was 4.0 or more and could not be measured. When this film was peeled off from the roll, it was found to have poor flatness (unevenness occurred) due to the wrinkles that had been rolled in, and it was in a state that it could not be used as a base film for microfilm. . Comparative Example 2 has a good winding appearance in the winding process, but
The film had scratches on the surface and had poor image quality for use with microfilm. On the other hand, the films of Examples 1 to 4 and Comparative Example 3 were wound into normal film rolls without any trouble. In the evaluation of image quality, Examples 1 to 4 and Comparative Examples 1 to
A diazo emulsion is applied to the film of step 3, and the original microfilm is closely printed to form a diazo microfilm. The microfilms of Examples 1 to 4 had high contrast between the line drawing and the background, and excellent image quality was obtained, and the enlarged image by the projector was bright and clear. Furthermore, there was very little deterioration in the sharpness of the image of the diazo microfilm with five generations of diazo prints. The microfilms of Comparative Examples 2 and 3 have blurred line drawings, low contrast with the background, image quality is considerably inferior to the original, and images enlarged by a projector are dark.Especially, the microfilms of Comparative Example 3 are caused by minute spots. Dark shadows appear on the screen in spots, making it impractical. From the above results, it has been found that the film of the present invention has excellent transparency, especially for use as a microfilm, and is also excellent in workability.

Claims (1)

[Scope of Claims] 1 A polyester film having a roughened surface on at least one side, which has a PV value [y (unit/μ)] and a CLA value [x (unit/μ)] indicating the surface roughness of the roughened surface. )] is in a range that simultaneously satisfies the following two equations: 5x+0.03≦y≦5x+0.25 0.003≦x≦0.0135, and the light transmittance at 350 nm is 68% or more, and the light transmittance at 550 nm is 83
% or more. 2 PV value [y (unit/μ)] and CLA value [x (unit/μ)] are in a range that simultaneously satisfies the following two equations: 5x+0.06≦y≦5x+0.21 0.004≦x≦0.012 Claim 1
The oriented polyester film described in Section 1. 3 PV value [y (unit/μ)] and CLA value [x (unit/μ)] are in a range that simultaneously satisfies the following two equations: 5x+0.07≦y≦5x+0.19 0.006≦x≦0.011 Claim 1
The oriented polyester film described in Section 1. 4. The oriented polyester film according to claim 1, which has a light transmittance of 73% or more at 350 nm. 5. The oriented polyester film according to any one of pages 1 to 3 of the claims, which has a light transmittance of 75% or more at 350 nm. 6. The oriented polyester film according to claim 1, which has a light transmittance of 85% or more at 550 nm. 7. The oriented polyester film according to claim 1, which has a light transmittance of 88% or more at 550 nm. 8 Claim 1 whose thickness is 50 to 250μ
The oriented polyester film described in any one of items 1 to 7.