JPH053377B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention has excellent smoothness, running characteristics, and wear resistance.
In particular, the present invention relates to an oriented polyester film that has excellent electromagnetic properties when used as a magnetic recording substrate. In general, polyesters such as polyethylene terephthalate are used for textiles, molded products, and other applications due to their excellent physical and chemical properties.
For magnetic tapes, floppy disks, photographs,
For condensers, packaging, X-ray film,
It is also widely used in a variety of applications for films such as microfilm. When used for these films, the slipperiness and abrasion resistance properties are major factors that determine the workability of the film manufacturing process and processing process in each application, as well as the quality of the product. In particular, when a magnetic layer is applied to the surface of a polyester film and used as a magnetic tape, the friction and abrasion between the coating roll and the film surface during application of the magnetic layer is extremely severe, and wrinkles and scratches are likely to occur on the film surface. Furthermore, even after the film coated with the magnetic layer is slit and processed into audio, video, or computer tapes, there are many guide parts, playback heads, etc. when pulling it out from a reel or cassette, winding it up, or performing other operations. Significant friction and wear occur between the two, causing scratches and distortion, as well as depositing white powdery substances due to scratches on the surface of the polyester film, which is often a major cause of missing magnetic recording signals, that is, dropouts. Furthermore, when used repeatedly as a magnetic tape, the coefficient of friction between it and metal guide rollers increases with the number of times it is used. There may be so-called squealing between the
Driving characteristics deteriorate. Among these, metal-coated and vapor-deposited magnetic tapes that require a high S/N ratio, such as video tapes that require surface smoothness, have very thin magnetic layers, so the base film used is The surface morphology of the magnetic layer directly becomes the surface morphology of the magnetic layer. Therefore, if the surface roughness of the base film is rough, the electromagnetic conversion characteristics of the videotape after coating or vapor deposition of the metal magnetic material will be significantly deteriorated. From the viewpoint of electromagnetic conversion characteristics, it is preferable to use a paste film with a perfectly smooth mirror surface free of inert inorganic particles and insoluble particles caused by catalyst residue, but the magnetic layer formed on such a paste film Since the surface remains mirror-like, its workability such as slipperiness and abrasion resistance is extremely poor, and its running durability is also extremely poor. Generally, to improve the slipperiness, abrasion resistance, and running durability of films, a method is adopted in which the contact area between guide rolls and the like is reduced by adding unevenness to the film surface. Methods for forming such particles include a method in which insoluble particles are precipitated from a contact residue of a polymer used as a film raw material, a method in which inert inorganic particles are added, and the like. Generally speaking, the larger the size of the particles in these raw polymers, the greater the effect of improving slipperiness. For precision applications such as video tapes, the large particles themselves can cause defects such as dropouts, and furthermore, the electromagnetic conversion characteristics can be significantly deteriorated, so the irregularities on the film surface must be as fine as possible. Currently, there are demands to satisfy contradictory characteristics at the same time. (Problems to be Solved by the Invention) The purpose of the present invention is particularly when an oriented polyester film is used as a base material for a magnetic tape, particularly a videotape base material such as a metal coated type or a vapor deposited type that requires surface smoothness. An object of the present invention is to provide an oriented polyester film having extremely good electromagnetic conversion characteristics and good running characteristics. (Means for solving the problems) The present invention provides polyester with an average particle size of 0.01.
0.01 to 0.5% by weight of at least one particle selected from silica and titanium oxide having a volume shape coefficient of 0.08 to π/6 and an average particle size of 0.1 to 0.1 μm.
Containing 0.05 to 0.3% by weight of calcium carbonate particles having a volume shape coefficient of 0.08 to π/6 with a diameter of 0.01 to 0.1 μm,
This is an oriented polyester film characterized by having electromagnetic conversion characteristics of grade 4 or higher. The oriented polyester film of the present invention has an ultra-smooth surface, and its processability such as slipperiness and abrasion resistance, as well as its running durability, are better than when silica particles or calcium carbonate particles are used alone or when other particles are added. It has excellent electromagnetic conversion properties, and is particularly suitable for use in videotapes that require surface smoothness, such as metal-coated and vapor-deposited types, with few defects such as dropouts. This is the heading that led to the present invention. The polyester used in the method of the present invention is a crystalline polyester containing polyethylene terephthalate, polyalkylene naphthalate, etc. Although not particularly limited, polyethylene terephthalate is particularly suitable, and in particular,
More than 80 mol% consists of ethylene terephthalate, and other copolymerized components include isophthalic acid, p-β-oxyethoxybenzoic acid, 2,6-
Naphthalenedicarboxylic acid, 4,4'-dicarboxyldiphenyl, 4,4'-dicarboxylbenzophenone, bis(4-carboxylphenyl)
Ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalate, cyclohexane-1,4
- Dicarboxylic acid components such as dicarboxylic acids, glycol components such as propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, ethylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, P - Oxycarboxylic acid components such as oxybenzoic acid and the like can be arbitrarily selected and used. In addition, a small amount of a compound containing an amide bond, urethane bond, ether bond, carbonate bond, etc. may be included as a copolymerization component. As a method for manufacturing the polyester, any manufacturing method can be applied, such as the so-called direct polymerization method in which aromatic dicarboxylic acid and glycol are directly reacted, and the so-called transesterification method in which dimethyl ester of aromatic dicarboxylic acid and glycol are transesterified. can do. The film may be either a uniaxially oriented film or a biaxially oriented film, but a biaxially oriented film is particularly preferred. In the present invention, the average particle size of silica and titanium oxide, which are the first components of the inert inorganic fine particles to be added, must be 0.01 to 0.1 μm, and 0.01 to 0.1 μm.
More preferably 0.09 μm. Particularly preferably 0.01~
It is 0.08 μm. If it is less than 0.01 μm, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.1 .mu.m, the electromagnetic conversion properties will be insufficient for magnetic tapes, especially video tapes that require surface smoothness such as metal-coated type and vapor-deposited type, which is not preferable. The amount added must be 0.01 to 0.5% by weight, more preferably 0.05 to 0.3% by weight, based on the polyester. 0.01
If it is less than % by weight, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the contrary, 0.5
If it exceeds % by weight, the electromagnetic conversion characteristics will be insufficient for use in magnetic tapes, particularly video tapes that require surface smoothness such as metal-coated and vapor-deposited types, and are therefore undesirable. The average particle size of calcium carbonate, which is the second component of the inert inorganic fine particles to be added, must be 0.01 to 0.1 μm, and more preferably 0.03 to 0.09 μm. Particularly preferably, it is 0.04 to 0.08 μm. If it is less than 0.01 μm, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.1 .mu.m, the electromagnetic conversion properties are insufficient for magnetic tapes, especially video tapes that require surface smoothness such as metal coating type and vapor deposition type, which is not preferable. In addition, the amount added is 0.05 to 0.3 to the polyester.
It is necessary to set it as weight%, and 0.08-0.2 weight% is more preferable. If it is less than 0.005% by weight, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.3% by weight, the electromagnetic conversion characteristics will be insufficient for magnetic tapes, especially video tapes that require surface smoothness such as metal-coated type and vapor-deposited type, which is not preferable. There are no limitations on the manufacturing method or other aspects of these particle components as long as they satisfy the conditions specified above. In addition, the relationship between the average particle diameter and the amount added of each particle component is as follows:
It can be arbitrarily selected as long as it satisfies the conditions specified above. As calcium carbonate, both natural products and synthetic products can be used. For example, any of heavy calcium carbonate, light calcium carbonate, and colloidal calcium carbonate may be used. These particles may be used without surface treatment or may be surface treated. Further, there are no particular limitations on whether or not a dispersion aid or agglomeration inhibitor is used. Further, it is preferable to use a volume shape coefficient of each particle in a range of 0.08 to π/6. If the volume shape coefficient of each particle is less than 0.08, the processability of the film deteriorates, which is not preferable. [However, the volumetric shape factor f is expressed by the following equation. f=v/D In ^the formula, v is the particle volume (μm ³ ), and D is the maximum diameter (μm) of the particle in the projected plane. ] The volume shape coefficient represents the degree of agglomeration of particles, and the closer to π/6, the closer to agglomeration or spherical shape. The average particle diameter of the calcium carbonate particles may be larger or smaller than the average particle diameters of the silica particles and titanium oxide particles, but it is more preferable that they are larger than the silica particles and titanium oxide particles. The average particle size referred to here is the sum of the equivalent spherical diameter particle size distribution calculated based on Stokes' formula 50
Refers to the diameter at the % point. In the method of adding fine particles to polyester in the present invention, they can be added at any stage in the polyester manufacturing process, but it is particularly preferable to add them before the initial condensation is completed. In addition, fine particles can be added to the polyester manufacturing process in either slurry or powder form, but in order to prevent particles from scattering and to improve supply accuracy and uniformity, they are added by dispersing them in a slurry form. It is particularly preferable to add it as a slurry of ethylene glycol (EG). When dispersing in slurry form, it is necessary to perform uniform dispersion so as to reproduce the original primary particles of each particle as much as possible. Furthermore, in order to obtain particles having a predetermined average particle size, pulverization treatment or classification operation of commercially available fine particles may be employed. When adding the particles as a slurry, the ratio of particles larger than 5 μm in the slurry to the total particles
It is particularly preferable to add 0.5% by weight or less from the viewpoint of reducing coarse particles. Furthermore, when the particles are added as a thriller to the polyester manufacturing process, the silica or titanium oxide slurry and the calcium carbonate slurry may be added at the same time or may be added separately. If they are added at the same time, they may be added from separate supply ports, or both slurries may be mixed uniformly before being added to the polyester manufacturing process.
Alternatively, a polyester containing a high concentration of individual particles within a range that does not agglomerate may be separately produced in advance and then blended to a predetermined particle concentration. Even if it contains fine particles precipitated during the polyester manufacturing process, so-called internal particles, as long as the average particle size and content are within a range that does not increase the number of coarse particles and do not have a negative effect on surface smoothness. I don't mind. If the film is used in such a way that only one side of the film comes into contact with a metal roll, only the contacting surface may contain the inert inorganic particles of the present invention, and the other surface may contain inert inorganic particles depending on the purpose. Alternatively, it may be a separate layer that does not contain it. (Example) Next, Examples and Comparative Examples of the present invention will be shown. All parts in the examples mean parts by weight unless otherwise specified. In addition, the measurement method used is shown below. (1) Processability of film A tape-like roll made by slitting a film into narrow widths is rubbed against a metal guide roll to process it at high speed.
When running for a long time, the magnitude of the tape tension after rubbing against the guide roll and the amount of white powder generated on the surface of the guide roll are each evaluated on a five-point scale with respect to a constant supply tension, and the following rankings are given. (a) Slip property 1st grade...Tension is high (many scratches) 2nd grade...Tension is slightly high (quite a lot of scratches) 3rd grade...Tension is medium (some scratches) 4th grade...Tension is somewhat low (almost no scratches) 5th grade...Tension Small (No scratches or eyelashes) (B) Abrasion resistance 1st grade...very much white powder generation 2nd grade...a lot of white powder generation 3rd grade...some white powder generation 4th grade...almost no white powder generation 5th grade...no white powder generation ( 2) Running durability Using the equipment shown in Figure 1, at 23℃ and relative humidity.
In an atmosphere of 65%, the rough side of the polyester film was measured with the guide pin of a commercially available home VTR (the maximum protrusion height measured with a stylus surface roughness meter).
0.15μm, center line average roughness is 0.008μm) at an angle of 3/4π (unit: radian), and a constant load is applied.
Angular velocity of the crank giving a tension of 50 grams
When the film was rotated at 8.0 rpm and the film was reciprocated 100 times, the increases in the dynamic friction coefficient and static friction coefficient from the initial dynamic friction coefficient and initial static friction coefficient (△μkd and △μks) were evaluated on a five-point scale.
It is expressed by the following ranking. 1st grade...friction coefficient increase 0.20 or more 2nd grade...0.15 to 0.20 3rd grade...0.10 to 0.15 4th grade...0.05 to 0.10 5th grade...less than 0.05 (3) Average particle size Shimadzu centrifugal sedimentation particle size distribution analyzer (CP Use the value at the 50% cumulative point in the equivalent sphere diameter distribution obtained by -50 type). (4) Film surface smoothness (TAR) The film surface was measured using a stylus-type three-dimensional surface roughness meter (SE-3AK) manufactured by Kosaka Institute.
Measurements are made over a reference length of 1 mm with a cutoff value of 0.25 mm in the longitudinal direction of the film under conditions of 2 μm and a load of 70 mg, and data in the height direction is imported into an external storage device every 2 μm with a quantization width of 0.00312 μm. Such measurements are carried out 150 times continuously at intervals of 2 μm in the transverse direction of the film, that is, over a width of 0.3 mm in the transverse direction of the film.
When the data in the height direction at this time is h (i, j) [i = 1 to 500, j = 1 to 150], the value obtained by calculating the following formula is expressed in μm. is TAR (three-day average roughness). TAR=1/75000 ₅₀₀ 〓 ^j=1 ₁₅₀ 〓 ^j=1 △h(i, j)
...() △h (i, j) = 1h (i, j) - 1/75000 _5
00 〓 ^j=1 ₁₅₀ 〓 ^j=1 h (i, j) 1 ... () (5) Number of coarse particles in the film A small amount of the film was sandwiched between two cover glasses and melt-pressed at 280℃. After quenching, the particles were observed using a phase-contrast microscope, and processed using an image analysis processing device Luzetskus 500 (manufactured by Nippon Regulator) to determine the number of particles with a maximum length of 5 μm or more in the particle image (per measurement area of 4.8 mm2 ^). The number of particles) is counted and ranked according to the number of particles as follows. 1st grade...51 pieces/4.8mm ² 2nd grade...21~50 pieces/4.8mm ² 3rd grade...11~20 pieces/4.8mm ² 4th grade...4~10 pieces/4.8mm ² 5th grade...0~3 pieces /4.8mm ² (6) Electromagnetic conversion characteristics (S/N ratio) S/N when the above film is made into magnetic tape
The ratio is measured by measuring a 50% white level signal at the optimum recording current for each tape, and using a video noise measuring device to measure the signal-to-noise ratio (S/N ratio) contained in the video demodulated signal during playback. The S/N ratio of each tape is evaluated on a five-level scale and expressed in the following rankings. 1st grade...S/N ratio small 2nd grade...S/N ratio slightly low 3rd grade...S/N ratio Same as commercially available standard tape 4th grade...S/N ratio somewhat large 5th grade...S/N ratio Large Example 1 Stirring device , using a continuous esterification reactor consisting of a two-stage complete mixing tank equipped with a partial condenser, a raw material inlet, and a product outlet, the system in which the esterification reaction product of the first esterification reactor exists is used. Molar ratio of EG to acid (TPA) 1.7
EG of TPA adjusted to and containing 289 ppm of antimony trioxide per TPA unit
The slurry was fed continuously. At the same time, an EG solution of magnesium acetate tetrahydrate and an EG solution of sodium acetate are passed through the reactor from a supply port different from the TPA EG slurry supply port. Mg atoms and Na atoms per polyester unit in the reaction product, respectively. as 100ppm and
It was continuously supplied at a concentration of 10 ppm, and the reaction was carried out at normal pressure for an average residence time of 4.5 hours and at a temperature of 255°C. This reaction product is continuously taken out of the system,
It was supplied to the second esterification reactor. 0.5 parts by weight of EG based on the polyester unit in the reaction product passing through the second esterification reactor, 64 ppm as P atoms in the EG solution of trimethyl phosphate
The average particle size is 0.04 μm and the volume shape factor is 0.48.
An EG slurry of silica and an EG slurry of calcium carbonate with an average particle size of 0.08 μm and a volume shape factor of 0.38 were continuously fed from separate feed ports so that the amounts of silica and calcium carbonate were 0.25% by weight and 0.15% by weight, respectively. The reaction was carried out at normal pressure for an average residence time of 5.0 hours and at a temperature of 260°C. The esterification reaction product is passed through a stirring device, a dephlegmator,
Polycondensation was carried out by continuously feeding the mixture into a two-stage continuous polycondensation reactor equipped with a raw material inlet and a product outlet to obtain a polyester having an intrinsic viscosity of 0.620.
The polymer was melt extruded at 290°C, stretched 3.5 times in the machine direction at 90°C, and 3.5 times in the transverse direction at 130°C, and then stretched at 220°C.
Table 1 shows the film properties of the 15 μm film obtained by heat treatment at °C. The obtained film has excellent electromagnetic conversion characteristics, surface smoothness, slipperiness, abrasion resistance, number of coarse particles, and running durability, especially for magnetic video tapes that require surface smoothness such as metal-coated and vapor-deposited types. Good in all characteristics. Comparative Examples 1 and 2 0.25% by weight of silica with a volumetric shape coefficient of 0.48 at an average particle size of 0.04 μm and 0.15% by weight of calcium carbonate with a volumetric shape coefficient of 0.38 at an average particle size of 0.08 μm were each used alone. Example 1 except for using
Table 1 shows the physical properties of the film obtained using the same method as above.
It was shown to. The films obtained in these comparative examples had poor running stability and slipperiness, and neither quality was sufficient for use in video tape applications that require surface smoothness, especially metal-coated and vapor-deposited films. It is. Comparative Example 3 Table 1 shows the film properties of a film obtained in the same manner as in Example 1 except that the amount of calcium carbonate added was changed to 0.40% by weight. The film obtained in this comparative example was inferior in terms of coarse particles, and did not have sufficient quality for use in video tapes requiring surface smoothness such as metal coating type and vapor deposition type. Comparative Example 4 Except for changing the amount of silica added to 1.20% by weight.
Table 1 shows the film properties of the film obtained in the same manner as in Example 1. The film obtained in this comparative example is inferior in electromagnetic characteristics, surface smoothness, and coarse particles, but has sufficient quality for video tape applications that require surface smoothness such as metal coating type and vapor deposition type. I haven't. Example 2 Table 1 shows the physical properties of a film obtained in the same manner as in Example 1, except that the average particle size of silica was changed to 0.08 μm, and the amounts of silica and calcium carbonate added were changed to 0.20% by weight and 0.20% by weight, respectively. It was shown to. The film obtained in this example has excellent electromagnetic conversion characteristics, surface smoothness, slipperiness, abrasion resistance, number of coarse particles and All characteristics of running resistance are good. Comparative Example 5 Except for changing the average particle size of silica to 0.35 μm,
Table 1 shows the physical properties of the film obtained in the same manner as in Example 2. The film obtained in this comparative example was inferior in terms of electromagnetic conversion characteristics, surface smoothness, and number of coarse particles, and was insufficient for use in video tapes that require surface smoothness, especially metal-coated and vapor-deposited types. The quality is incredible. Example 3 Addition amounts of both silica and calcium carbonate
Table 1 shows the physical properties of a film obtained in the same manner as in Example 1 except that the content was changed to 0.10% by weight. The film obtained in this example has electromagnetic conversion characteristics,
It has good properties in terms of surface smoothness, slipperiness, abrasion resistance, number of coarse particles, and running durability. Example 4 Table 1 shows the physical properties of a film obtained in the same manner as in Example 1, except that 0.20% by weight of titanium oxide having an average particle size of 0.03 μm and a volume shape coefficient of 0.35 was used instead of silica. The film obtained in this example has good electromagnetic characteristics, surface smoothness, slipperiness, abrasion resistance, number of coarse particles, and running durability. Comparative Example 6 Table 1 shows the physical properties of a film obtained in the same manner as in Example 2 except that silica having a volumetric shape factor of 0.06 was used. The film obtained in this comparative example was inferior in processability.

【table】

[Table] (Effects of the Invention) As described above, the film obtained by the present invention has excellent electromagnetic conversion characteristics, especially for use in video tapes that require surface smoothness, such as metal coating type and vapor deposition type. It also has good slip properties, abrasion resistance, and running durability, and is characterized by extremely low generation of coarse particles that cause drop-out defects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a tape testing machine for measuring the repeated running performance of a film on a rough surface. Each part will be briefly explained below. 1: Crank, 2, 4, 6, 8: Free roll, 3, 7: Tension detection device, 9: Load, 5: Commercially available
VTR guide pin.

Claims (1)

[Claims] 1 Polyester with an average particle size of 0.01 to 0.1 μm
0.01 to 0.5% by weight of at least one kind of particles selected from silica and titanium oxide having a volume shape coefficient of 0.08 to π/6, and an average particle size of 0.01 to 0.1μ.
An oriented polyester film containing 0.05 to 0.3% by weight of calcium carbonate particles having a volume shape coefficient of 0.08 to π/6 in m and an electromagnetic conversion property of grade 4 or higher.