JP2991272B2 - Biaxially oriented polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biaxially oriented polyester film, and more particularly to a biaxially oriented polyester film suitable as a base film for a magnetic tape.

[0002]

2. Description of the Related Art Today, saturated polyesters produced industrially, especially polyethylene terephthalate (hereinafter referred to as P
Abbreviated as ET. ) Has excellent physical and chemical properties. In addition, biaxially oriented polyester films in which fine particles of inorganic compounds or organic compounds called lubricant particles are added to polyester are magnetic tapes such as audio tapes and video tapes. , For condenser, for photography, for packaging, O
Widely used for HP.

Recently, with the speeding up of the magnetic tape manufacturing process, there is a demand for a film having more excellent wear resistance in a calendaring process in the magnetic tape manufacturing process.
The calendering step is a step of applying a magnetic layer composition on a polyester film and drying to form a magnetic layer, and then smoothing the surface of the magnetic layer. In this calendering step, the film passes between calender rolls to which extremely high pressure is applied, so that projections on the film surface formed mainly by the lubricant are scraped off and abrasion powder is generated. If such abrasion powder adheres to the surface of the calendar roll, the surface of the magnetic layer of the film becomes rough, resulting in a decrease in the electrical properties of the resulting magnetic tape. When a film having poor abrasion resistance is used as a magnetic tape, abrasion powder is also generated in a traveling system in a tape deck, and as a result, the electrical characteristics of the magnetic tape are reduced and dropout is caused.

[0004] Recently, in addition to abrasion resistance, demands for scratch resistance have been increasing in base films for magnetic tapes. Scratch refers to scratches (for example, scratches on a tape caused by a cassette pin during high-speed dubbing) at a portion where the magnetic tape contacts, and scratches caused by abrasion powder generated in a running system in a tape deck. Such a magnetic tape having poor scratch resistance causes contamination in the manufacturing process and causes an increase in dropout. The above-mentioned improvement in wear resistance and scratch resistance leads to improvement in quality of the magnetic tape and is very important.

As a method for improving abrasion resistance and scratch resistance, for example, Japanese Unexamined Patent Publication No. 1-311131 discloses a method in which certain fine particles such as inert fine particles having a Mohs hardness of 6 or more are used as a lubricant in a polyester film. Are described. However, in this method, it is not easy to sufficiently disperse the inert fine particles having a Mohs hardness of 6 or more such as alumina, so that the primary particles are present in the polyester film as secondary aggregated particles in which a plurality of primary particles are aggregated. Although not improved, the film does not have sufficient abrasion resistance. Also, when a large amount of inert fine particles having a Mohs' hardness of 6 or more such as alumina is blended in a large amount into a polyester film, the slitter blade is easily damaged when slitting the film, which is not preferable.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a film which is excellent in abrasion resistance and therefore does not generate abrasion powder of a film in a calendaring process. Another object of the present invention is to provide a biaxially oriented polyester film which is free from burrs, whiskers and powder when slitting a film, has little damage to a slitter blade, and has excellent scratch resistance.

[0007]

The present invention is directed to a polyester film comprising an acid component mainly composed of an aromatic dicarboxylic acid and a glycol component, and comprising a calcium carbonate having the following physical properties (a) to (d). Fine particles 100-2000
A biaxially oriented polyester film characterized in that it is contained in a range of 0 ppm. (A) In the shape examined by an electron micrograph, a value of 0.
At least 5% by weight of needle-like calcium carbonate particles having an aspect ratio (ratio of major axis / minor axis) of 2 or more, comprising primary particles of 0025 to 0.1 μm connected in a chain, is contained. 005 μm ≦ DS1 ≦ 0.5 μm (c) 0.0025 μm ≦ DS2 ≦ 0.1 μm (d) 0.01 μm ≦ DP1 ≦ 0.4 μm, where DS1: average particle of major axis of ultrafine calcium carbonate examined by electron micrograph Diameter (μm) DS2: Average particle diameter (μm) of ultra-fine calcium carbonate as determined by electron micrograph DP1: Light transmission type particle size distribution analyzer (SA- manufactured by Shimadzu Corporation)
In the particle size distribution measured using CP3), the particle diameter (μ
m).

[0008] In a preferred embodiment, the acicular calcium carbonate of the present invention is ultrafine calcium carbonate particles prepared by disintegrating vaterite crystalline calcium carbonate. In an alcohol system containing at least one selected from copper chlorides, a calcium compound such as calcium hydroxide, calcium oxide or calcium chloride is reacted with carbonic acid or carbonate such as carbon dioxide, sodium carbonate or ammonium carbonate. Ultra-fine particles of calcium carbonate obtained by aging a calcium carbonate matrix of vaterite crystals obtained by aging to collapse the calcium carbonate matrix of vaterite crystals.

Next, the present invention will be described in detail. The biaxially oriented polyester film of the present invention contains, as a main component, a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film-forming properties, especially by melt-forming. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfondicarboxylic acid, diphenylketonedicarboxylic acid, and anthracenedicarboxylic acid. These can be used alone or in combination of two or more. Examples of the fatty acid glycol include alicyclic diols such as polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol and the like, and cyclohexadimethanol. And these can be used alone or in combination of two or more.

In the present invention, as the polyester, for example, those containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferably used. Among such polyesters, for example, polyethylene terephthalate and polyethylene-2,6-naphthalate, as well as, for example, 8
A copolymer in which 0 mol% or more is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid and 80 mol% or more of all glycol components is ethylene glycol is preferred. At that time, not more than 20 mol% of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or naphthalenedicarboxylic acid, and also fatty acid dicarboxylic acids such as adipic acid and sebacic acid; cyclohexane-1, It may be an alicyclic dicarboxylic acid such as 4-dicarboxylic acid. 20 mol% of all glycol components
The following can be the above glycols other than ethylene glycol or, for example, hydroquinone, 2,2
Aromatic diols such as -bis (4-hydroxyphenyl) propane; fatty acid diols containing aromatics such as 1,4-dihydroxymethylbenzene; polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol (poly) Oxyalkylene glycol) and the like.

In the polyester of the present invention, a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid; a fatty acid oxyacid such as ω-hydroxycapric acid is used as a dicarboxylic acid component and an oxycarboxylic acid. Those that copolymerize or combine at 20 mol% or less based on the total amount of the components are also included. Further, in the polyester of the present invention, a tricarboxylic or polyfunctional polycarboxylic acid or a polyhydroxy compound such as trimellitic acid or pentane in an amount in a substantially linear range, for example, 2 mol% or less based on the total acid content. Those obtained by copolymerizing erythritol and the like are also included.

[0012] The calcium carbonate contained in the biaxially oriented polyester film of the present invention has a shape, as examined by an electron micrograph, of which primary particles of 0.0025 to 0.1 µm are formed in a chain. Aspect ratio (major axis /
Ratio of the minor axis) is calcium carbonate containing at least 5% by weight of acicular calcium carbonate particles of 2 or more,
Preferably 30% by weight or more, more preferably 50% by weight
The above content is good. When the content of the acicular calcium carbonate is less than 5% by weight, and when the aspect ratio of the acicular calcium carbonate is less than 2, the biaxially oriented polyester film of the present invention having both abrasion resistance and scratch resistance is obtained. I can't.

The size of the ultrafine calcium carbonate contained in the biaxially oriented polyester film of the present invention is as follows:
It is sufficient that the average particle diameter DS1 (μm) of the major axis and the average particle diameter DS2 (μm) of the minor axis of the ultrafine calcium carbonate examined by an electron micrograph satisfy the following expressions (b) and (c), and are preferable. May satisfy the expressions of (e) and (f). (B) 0.005 μm ≦ DS1 ≦ 0.5 μm (c) 0.0025 μm ≦ DS2 ≦ 0.1 μm (e) 0.005 μm ≦ DS1 ≦ 0.2 μm (f) 0.0025 μm ≦ DS2 ≦ 0.05 μm

The ultrafine calcium carbonate particles were measured by using a light transmission type particle size distribution analyzer (SA-CP3 manufactured by Shimadzu Corporation).
May satisfy the following expression (d), preferably satisfy the expression (g), and more preferably satisfy the expression (h). (D) 0.01 μm ≦ DP1 ≦ 0.4 μm (g) 0.01 μm ≦ DP1 ≦ 0.2 μm (h) 0.01 μm ≦ DP1 ≦ 0.1 μm

When a calcium carbonate having a DS1 value of more than 0.5 μm, a calcium carbonate having a DS2 value of more than 0.1 μm, and a calcium carbonate having a DP1 value of more than 0.4 μm are used for the polyester film of the present invention. Coarse protrusions are likely to be formed on the film to be formed, and when such a film is used for a magnetic tape, the coarse protrusions promote the generation of scratches on the tape surface or cause dropout. Further, it is difficult to produce calcium carbonate having a DS1 value smaller than 0.005 μm, calcium carbonate having a DS2 value smaller than 0.0025 μm, and a calcium carbonate having a DP1 value smaller than 0.01 μm.

There are no particular restrictions on the method for producing ultrafine calcium carbonate particles having the above-mentioned physical properties. Examples of the method include a carbon dioxide gas method in which an aqueous suspension of calcium hydroxide is reacted with carbon dioxide gas. Examples thereof include a solution method in which an aqueous solution of a carbonate such as sodium carbonate is reacted, and an alcohol solution method in which a calcium compound is reacted with carbon dioxide or carbonate in an alcohol system. The crystalline form of calcium carbonate produced by these methods is not particularly limited, and may be any of calcite, aragonite, vaterite, and amorphous.

The calcium carbonate contained in the biaxially oriented polyester film of the present invention, which is used in a high industrial application field, includes calcium carbonate ultrafine particles prepared by collapsing vaterite crystalline calcium carbonate. 2 of the present invention which is suitable and is used for higher-grade applications
(E) contained in the axially oriented polyester film,
The calcium carbonate having the various properties (f) and (h) is selected from zinc, aluminum and copper chlorides.
Calcium carbonate of vaterite crystal obtained by reacting a calcium compound such as calcium hydroxide, calcium oxide, calcium chloride, etc. with a carbonic acid or carbonate such as carbon dioxide, sodium carbonate, ammonium carbonate, etc. in an alcohol system containing seeds or more. Ultra-fine calcium carbonate particles obtained by aging the base material to collapse the calcium carbonate base material of the vaterite crystals are most preferable.

The content of the ultrafine calcium carbonate particles in the biaxially oriented polyester film of the present invention is from 100 to 2
0000 ppm, preferably 1 ppm.
500 to 10000 ppm. If the content of the ultrafine calcium carbonate particles exceeds 20,000 ppm, the film surface may be damaged on the contrary, and the heat resistance of the polyester film is reduced. If the content of the ultrafine calcium carbonate particles is less than 100 ppm, the obtained polyester film does not have sufficient abrasion resistance and scratch resistance.

The calcium carbonate used in the biaxially oriented polyester film of the present invention may be an organic acid such as a fatty acid in order to improve the affinity with ethylene glycol or polyester, and further enhance the dispersibility and stability of the calcium carbonate particles. , Resin acid, acrylic acid, methacrylic acid, oxalic acid,
Surface treating agents such as organic acids such as citric acid, inorganic acids such as tartaric acid, phosphoric acid, condensed phosphoric acid, hydrofluoric acid, polymers thereof, alkali metal salts, ammonium salts, alkaline earth metal salts, and esters thereof. It is preferable to use a coupling agent such as silane, titanium or the like, or a dispersant such as a surfactant, etc., by surface treatment according to a conventional method, and generally used in an amount of 5% by weight or less based on calcium carbonate.

As described above, in the present invention, the effect is exhibited when ultrafine calcium carbonate particles having a specific shape and a specific particle size distribution are contained in a polyester film. Becomes significantly more noticeable when combined. First, in the case of a film containing at least 80 mol% of ethylene terephthalate units, if the refractive index in the thickness direction of the film is less than 1.493, the effect of improving the lubricity and abrasion resistance of the film is insufficient. Further, the refractive index in the thickness direction of the film is 1.49.
When it is 3 or more, the adhesiveness with the magnetic layer can be improved, which is preferable. The refractive index in the film thickness direction is preferably from 1.494 to 1.505. For a film having such physical properties, for example, in the case of sequential biaxial stretching, the longitudinal stretching temperature is 105 to 115 higher than the normal stretching temperature by 5 to 30 ° C.
It can be obtained by setting the temperature to about ° C.

A second combination in which the effect of the present invention is particularly exhibited is, in the case of a film containing at least 80 mol% of ethylene terephthalate units, the sum of the longitudinal Young's modulus and the transverse Young's modulus of the film containing the particles. 900 kg / mm
² or more, more preferably 1000 kg / mm ² or more,
Particularly preferably, it is 1100 kg / mm ² . Usually, when stretched so strongly to have a high strength, particles are likely to fall off from the film surface layer, and the abrasion resistance of the film is deteriorated.However, when the calcium carbonate ultrafine particles of the present invention are used, Such a dropout phenomenon tends to decrease.

Such a high-strength film can be obtained, for example, by the following known film forming method. That is,
The substantially non-oriented unstretched sheet is 3.0 to 6.0 times in the machine direction at 80 to 120 ° C, and then 3.0 to 6.0 in the transverse direction.
This is a method of performing double stretching and heat treatment at 170 to 240 ° C. Of course, after sequential biaxial stretching or simultaneous biaxial stretching in the longitudinal and transverse directions, the film is further subjected to 1.
After performing the re-stretching by a factor of 05 to 2.5, a method of performing a heat treatment may be employed. At this time, heat setting before re-longitudinal stretching, relaxation after re-longitudinal stretching,
Before or after re-longitudinal stretching, it is also possible to appropriately employ a technique such as micro-magnification longitudinal stretching. In addition, re-stretching may be similarly performed in the lateral direction.

A third combination in which the effect of the present invention is particularly exhibited is a case where the above-mentioned ultrafine particles of calcium carbonate are blended in a film containing polyethylene-2,6-naphthalate units in an amount of 80 mol% or more. Especially polyethylene-
Films containing 2,6-naphthalate units in an amount of 80 mol% or more have attracted attention because of their excellent mechanical strength and heat resistance. However, such films are often strict in terms of film running speed and tension. Since it is used under conditions, improvement of wear resistance is particularly desired. In particular, the sum of the Young's modulus in the vertical direction and the Young's modulus in the horizontal direction of the film is 1
300 kg / mm ² or more, more preferably 1400 k
g / mm ² or more, particularly preferably 1500 kg / mm ²
By doing so, the effect of improving the wear resistance is remarkably obtained.

In the case of polyethylene-2,6-naphthalate, such a high-strength film can be obtained by the same method as for polyethylene terephthalate except that the stretching temperature is increased. That is, a substantially non-oriented unstretched sheet is stretched at 140 to 120 ° C in the longitudinal direction at 3.0 to 6.0.
And then stretched 3.0 to 6.0 times in the transverse direction,
Heat treatment at 260 ° C. Of course, after sequential biaxial stretching or simultaneous biaxial stretching in the vertical and horizontal directions, 140-200 ° C.
After re-stretching in the longitudinal direction by 1.05 to 4.0 times at the temperature described above, a method of performing a heat treatment can also be adopted. At this time, it is also possible to appropriately adopt a technique such as heat setting before re-longitudinal stretching, relaxation after re-longitudinal stretching, or before or after re-longitudinal stretching, or micro-longitudinal stretching. In addition, re-stretching may be similarly performed in the lateral direction. Further, the polyester of the present invention may be used on the front side or the back side of the laminated film.

As described above, in the present invention, when calcium carbonate ultrafine particles having a specific shape and a specific particle size distribution are contained in a polyester film, the characteristics of the polyester film can be improved. In such a case, the effect can be particularly enjoyed. In the present invention, it is possible to further improve the running properties, abrasion resistance, scratch resistance and the like of the film by using one or more other particles in a range not exceeding the gist. Precipitated particles can be mentioned as one of such particles. The term “precipitated particles” as used herein refers to, for example, those that precipitate in a reaction system by polymerizing a system using an alkali metal or alkaline earth metal compound as a transesterification catalyst by a conventional method. Additive particles can also be used as one of the particles used in combination. The term “added particles” as used herein refers to particles added to the polyester from the outside.Specifically, kaolin, talc, carbon black, molybdenum sulfide, gypsum, aluminum oxide, barium sulfate, lithium fluoride, calcium fluoride, zeolite, phosphoric acid Examples thereof include calcium, silicon dioxide, titanium dioxide, and heat-resistant polymer fine particles. Further, in addition to the calcium carbonate ultrafine particles used in the present invention, particle diameter, shape,
Calcium carbonates having different crystal forms may be used in combination. When particularly suitable combination particles among the above-mentioned added particles are classified by Mohs 'hardness, examples of the added particles having a Mohs' hardness of less than 2.5 include heat-resistant polymer fine particles and kaolin. As a typical example of heat-resistant polymer fine particles,
For example, a monovinyl compound having only one aliphatic unsaturated bond in a molecule and two or more aliphatic unsaturated bonds in a molecule as a crosslinking agent, as described in JP-B-59-5216. Can be exemplified, but not limited thereto, for example, using fine particles of a fluororesin such as a thermosetting epoxy resin, a benzoguanamine resin or polytetrafluorethylene. You can also. These heat-resistant polymer fine particles are substantially spherical, and a preferable particle size that can be used together with the calcium carbonate ultrafine particles used in the present invention is 0.05.
The addition amount is 0.05 to 2% by weight with respect to the polyester film, and the combined ratio to the calcium carbonate ultrafine particles used in the present invention is 5 to 250 parts by weight based on 100 parts by weight of the calcium carbonate ultrafine particles. It is.

As to kaolin, a film having good abrasion resistance can be easily obtained, and any type of natural kaolin, synthetic kaolin, calcined or unfired may be used.
Also, the shape can be arbitrarily selected and used together, such as a plate shape, a column shape, a spherical shape, a spindle shape, and an egg shape. The preferred particle size of kaolin that can be used in combination with the ultrafine calcium carbonate particles used in the present invention is 0.1.
The addition amount is 0.05 to 2% by weight based on the polyester film, and the proportion of the calcium carbonate ultrafine particles used in the present invention is 20 to 500% by weight based on 100 parts by weight of the calcium carbonate ultrafine particles. Department.

Examples of the added particles having a Mohs' hardness of 2.5 or more and less than 5 include calcium carbonate, which may be natural calcium carbonate or synthetic calcium carbonate, and carbon dioxide produced by a reaction between carbon dioxide and lime milk. It may be synthesized by any of the following synthesis methods: an aqueous solution method typified by the reaction of calcium chloride and sodium carbonate, and a carbon dioxide gas method in alcohol. The crystal type may be any of calcite, aragonite, vaterite, and amorphous, and the shape is cubic, spherical, elliptical,
It can be arbitrarily selected such as a plate, a column, and a needle. Among them, calcite-type spherical and cubic calcium carbonate, vaterite-type spherical, elliptical spherical, and stone-like calcium carbonate are preferable from the viewpoint of particle morphology and dispersibility, and they can impart good lubricity to a polyester film, and thus the present invention. It can be used in combination with the calcium carbonate ultrafine particles used in the above. The preferred particle size of calcium carbonate that can be used in combination with the ultrafine calcium carbonate particles used in the present invention is 0.1 to 5 μm, and the average particle size of the ultrafine calcium carbonate particles used in the present invention is 1.2.
Calcium carbonate having an average particle diameter twice or more is preferred. The amount of addition is 0.05 to 2% by weight based on the polyester film, and the proportion used in combination with the ultrafine calcium carbonate particles used in the present invention is 20 to 500 parts by weight based on 100 parts by weight of the ultrafine calcium carbonate particles.

Examples of the additive particles having a Mohs hardness of 5 or more include synthetic spherical silica and aluminum oxide. Synthetic spherical silica that can impart good running characteristics to polyester film because its shape is almost spherical, monodisperse spheres of hydrous silica are formed from the hydrolysis of ethyl orthosilicate, and then dehydrated to form a three-dimensional silica bond. Examples of the method include a method of producing by essentially growing, but any method of synthesizing substantially spherical silica may be used regardless of the production method. The preferred particle size of the synthetic spherical silica that can be used in combination with the ultrafine calcium carbonate particles used in the present invention is 0.1 to 3 μm, and the amount of addition is 0.05 to 2% by weight based on the polyester film. The combined ratio of the ultrafine particles is 20 parts by weight with respect to 100 parts by weight of the ultrafine calcium carbonate particles.
５００500 parts by weight.

Aluminum oxide usually has a primary particle diameter in the range of 0.005 to 0.04 μm. Therefore, the aluminum oxide is used in combination with the ultrafine calcium carbonate particles used in the present invention to improve the scratch resistance of the polyester film. Can be improved. Examples of the method for producing this aluminum oxide include a thermal decomposition method using anhydrous aluminum chloride as a raw material, and an ammonium alum pyrolysis method. However, there is no particular limitation on these production methods, and delta type and gamma type are preferably used. Can be. The preferred particle size of aluminum oxide that can be used in combination with the calcium carbonate ultrafine particles used in the present invention is 0.1 μm.
The addition amount is 0.05 to 2% by weight based on the polyester film, and the combined ratio with respect to the calcium carbonate ultrafine particles used in the present invention is 100 to 1000 parts by weight based on 100 parts by weight of the calcium carbonate ultrafine particles. is there.

By blending calcium carbonate ultrafine particles having a specific shape, particle size and particle size distribution and the above-mentioned additive particles as required, a polyester film which is extremely excellent, particularly suitable for a magnetic recording medium Can be obtained. In producing the polyester containing the ultrafine calcium carbonate particles of the present invention, it is preferable that the ultrafine calcium carbonate particles and additional particles used in the present invention are added during the polyester synthesis reaction. It is particularly preferable to add the compound at the end of the transesterification reaction or esterification reaction and before the start of the polycondensation reaction. The particles to be added are usually added as a slurry of ethylene glycol, but if necessary, may be subjected to treatment such as crushing, dispersion, classification, and filtration in advance.

The concentration of the slurry in the ethylene glycol to be added is 3 to 50% by weight, preferably 10 to 40% by weight. If the particle concentration of the slurry is less than 3% by weight, the use amount of ethylene glycol increases, and the unit consumption of ethylene glycol increases, which is not preferable. When a slurry having a particle concentration exceeding 50% by weight is added, the dispersibility of the particles gradually deteriorates.

As the polycondensation reaction catalyst for the synthesis of polyester, Sb, Ti. Commonly used catalysts such as Ge, Sn and Si compounds are used alone or in combination. In general, when a polyester containing inorganic fine particles is produced, an alkali metal salt or an alkaline earth metal salt, phosphoric acid, phosphoric acid and the like are used for the purpose of improving the dispersibility of the inorganic fine particles and the electrostatic adhesion of the obtained film. An alkyl ester or a derivative thereof is added. When the biaxially oriented polyester film of the present invention is produced, the molar ratio (phosphoric acid or its derivative) / ((alkali acid) in which an alkali metal salt or an alkaline earth metal salt and phosphoric acid, a phosphoric acid alkyl ester, or a derivative thereof are added. Metal) / 2 +
(Alkaline earth metal)) is preferably 0.5 to 0.9. When the above molar ratio is less than 0.5 or more than 0.9, aggregation of the ultrafine calcium carbonate particles used in the present invention is liable to occur, and coarse particles are generated in the polyester. The magnetic tape that is used is likely to cause dropout.

The film of the present invention, which is particularly suitable for a magnetic recording medium, can be obtained for the first time by a combination of specific particles and specific film physical properties. 005 to 0.1 μm, preferably 0.007 to 0.08 μm, and 0.01 to 0.1 μm.
~ 0.03 µm is more preferred.

The film of the present invention has extremely good abrasion resistance and scratch resistance during high-speed running. Therefore, the film is awarded as a base film for video tapes, and particularly when used as an audio film. It can be effective.
Of course, if necessary, it can also be used for dielectric, packaging, plate making and other uses of capacitors.

[0035]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

The methods for producing calcium carbonate used in the examples and comparative examples are described below. Calcium carbonate A To a methanol suspension of calcium hydroxide prepared by adding 13 kg of calcium hydroxide to 250 liters of methanol and further adding zinc chloride equivalent to 5 mol% with respect to calcium hydroxide, was stirred at a temperature of 15 ° C. Then, carbon dioxide gas was blown in at a flow rate of 500 liter / min for 2.5 hours to adjust the pH in the system to 7.0, and then further blown under the same conditions for 1 hour to prepare a hard gel. The hard gel was allowed to stand for 72 hours to convert the gel to a methanol suspension. As a result of observing calcium carbonate in the obtained methanol suspension using an electron microscope and an X-ray diffractometer, it was spherical calcium carbonate of vaterite type crystal having a particle diameter of about 0.8 μm. Ethylene glycol was added to the methanol suspension and stirred to prepare a mixed slurry of calcium carbonate, methanol and ethylene glycol.
Next, the mixed slurry was distilled to prepare an ethylene glycol dispersion of calcium carbonate.

The ethylene glycol dispersion was heated, and
The mixture was kept at 20 ° C. for 2 hours to disintegrate the spherical calcium carbonate of the vaterite type crystal in the ethylene glycol dispersion to prepare an ethylene glycol dispersion of calcium carbonate A. The solid concentration of calcium carbonate A in the ethylene glycol dispersion was 10% by weight. Observation of calcium carbonate in the ethylene glycol dispersion using an electron microscope and an X-ray diffractometer revealed that the calcium carbonate A
Are needle-shaped, vaterite-type crystal ultrafine calcium carbonate particles having an aspect ratio of 5 to 10 and composed of particles of 0.007 μm connected in a chain, and DS1 of 0.03 to 0.3.
07 μm and DS2 were 0.007 μm. DP1 measured using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 was 0.07 μm.

Calcium carbonate B Specific gravity: 1.050, temperature: 8 ° C., 7000 liters of lime milk, 30 m ³ / mi of furnace gas having a carbon dioxide concentration of 27% by weight.
n at a flow rate of n to carry out a carbonation reaction.
An aqueous suspension of calcium carbonate having an H of 9.0 was obtained. Observation of this calcium carbonate with an electron microscope revealed that the primary particle diameter was 0.04 μm. Then 3
The mixture was stirred at 0 ° C for 5 hours, and the aqueous solution of calcium carbonate was stirred at 25 ° C.
Was dehydrated using a filter press when the pH reached 11.7, to obtain a dehydrated cake having a calcium carbonate solids concentration of 45% by weight. Next, water was again added to the obtained dehydrated cake, followed by stirring to obtain a calcium carbonate aqueous suspension having the same concentration as the calcium carbonate aqueous suspension before dehydration. The pH of the aqueous calcium carbonate suspension was 11.3. Magnesium chloride was added to the calcium carbonate aqueous suspension at 5% by weight based on the solid part of calcium carbonate, and the mixture was stirred at 25 ° C. for 72 hours. Next, carbon dioxide gas was passed again to lower the pH of the aqueous calcium carbonate suspension to 7.0.

An aqueous suspension was again dehydrated on the calcium carbonate using a filter press, and ethylene glycol was added to the obtained dehydrated cake and stirred to prepare a mixed slurry of calcium carbonate, water and ethylene glycol. Next, the mixed slurry was distilled to prepare an ethylene glycol dispersion of calcium carbonate B. The solid concentration of calcium carbonate B in the ethylene glycol dispersion was 10% by weight. As a result of observing the calcium carbonate in the ethylene glycol dispersion using an electron microscope and an X-ray diffractometer, the calcium carbonate B was found to be acicular, having an aspect ratio of 5, composed of 0.06 μm particles connected in a chain. Are ultrafine calcium carbonate particles of calcite crystal, DS1 is 0.3μ
m and DS2 were 0.06 μm. In addition, DP1 measured using a centrifugal sedimentation type particle size distribution analyzer SA-CP3
Was 0.07 μm.

To 7000 liters of lime milk having a specific gravity of 1.050 and a temperature of 8 ° C. with calcium carbonate C, a furnace gas having a carbon dioxide gas concentration of 27% by weight was supplied at 30 m ³ / mi.
n at a flow rate of n to carry out a carbonation reaction.
An aqueous suspension of calcium carbonate having an H of 9.0 was obtained. Observation of this calcium carbonate with an electron microscope revealed that the primary particle diameter was 0.04 μm. Then 3
The mixture was stirred at 0 ° C for 5 hours, and the calcium carbonate aqueous suspension was stirred at 25 ° C.
Was dehydrated using a filter press when the pH reached 11.7, to obtain a dehydrated cake having a calcium carbonate solids concentration of 45% by weight. Next, water was again added to the obtained dehydrated cake, followed by stirring to obtain a calcium carbonate aqueous suspension having the same concentration as the calcium carbonate aqueous suspension before dehydration. The pH of the aqueous calcium carbonate suspension was 11.3. Carbon dioxide gas was again passed through this aqueous calcium carbonate suspension to lower the pH of the aqueous calcium carbonate suspension to 7.0.

The aqueous calcium carbonate suspension was again dehydrated using a filter press, and ethylene glycol was added to the obtained dehydrated cake and stirred to prepare a mixed slurry of calcium carbonate, water and ethylene glycol. Next, the mixed slurry was distilled to prepare an ethylene glycol dispersion of calcium carbonate C. The solid concentration of calcium carbonate C in the ethylene glycol dispersion was 10% by weight.
As a result of observing calcium carbonate in the ethylene glycol dispersion using an electron microscope and an X-ray diffractometer, DS1 and DS2 were both 0.05 μm cubic and ultrafine calcium carbonate fine particles of calcite crystal having an aspect ratio of 1. Met. DP1 measured using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 was 0.18 μm.

Calcium carbonate D Commercial product T of acicular, aragonite-type crystal calcium carbonate T
Ethylene glycol was added to P-123 (Okutama Industry Co., Ltd.) to prepare an ethylene glycol dispersion of calcium carbonate D. The solid concentration of calcium carbonate D in the ethylene glycol dispersion was 10% by weight. As a result of observing the calcium carbonate in the ethylene glycol dispersion using an electron microscope and an X-ray diffractometer, the calcium carbonate D was ultra-fine calcium carbonate of acicular aragonite crystals having an aspect ratio of 5 to 10, DS1 Is 1-2
μm and DS2 were 0.2 μm. In addition, DP1 measured using a centrifugal sedimentation type particle size distribution analyzer SA-CP3
Was 0.7 μm.

Next, a method for producing polyethylene terephthalate used in Examples and Comparative Examples will be described below. Polyethylene terephthalate A 100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol and 0.09 parts by weight of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. The temperature was raised to 230 ° C. over 4 hours, and the transesterification reaction was substantially completed. Next, an ethylene glycol dispersion of calcium carbonate A was used as a calcium carbonate A solid content of 0.1%.
7 parts by weight were added. After adding an ethylene glycol dispersion of calcium carbonate A, 0.03 parts by weight of phosphoric acid and 0.04 parts by weight of antimony trioxide were further added, and a polycondensation reaction was carried out for 4 hours to obtain polyethylene terephthalate A having an intrinsic viscosity of 0.60. .

Polyethylene terephthalate B A transesterification reaction and a polycondensation reaction were carried out in exactly the same manner as for polyethylene terephthalate A except that calcium carbonate A was changed to calcium carbonate B, to obtain polyethylene terephthalate B having an intrinsic viscosity of 0.63.

Polyethylene terephthalate C A transesterification reaction and a polycondensation reaction were carried out in exactly the same manner as for polyethylene terephthalate A except that calcium carbonate A was changed to calcium carbonate C to obtain polyethylene terephthalate C having an intrinsic viscosity of 0.63.

Polyethylene terephthalate D A transesterification reaction and a polycondensation reaction were carried out in exactly the same manner as for polyethylene terephthalate A except that calcium carbonate A was changed to calcium carbonate D, to obtain polyethylene terephthalate D having an intrinsic viscosity of 0.63.

Polyethylene terephthalate E A transesterification reaction and a polycondensation reaction were carried out in exactly the same manner as for polyethylene terephthalate A except that no particles were added, to obtain polyethylene terephthalate E having an intrinsic viscosity of 0.63.

Polyester terephthalate F Transesterification and polycondensation were carried out in exactly the same manner as for polyethylene terephthalate A except that 0.6 parts by weight of monodispersed spherical silica having an average particle diameter of 0.3 μm was added instead of calcium carbonate A. The reaction was performed to obtain polyethylene terephthalate F having an intrinsic viscosity of 0.63.

Polyethylene terephthalate G In the same manner as for polyethylene terephthalate F, except that 0.6 parts by weight of a porous spherical calcium carbonate of monodispersed calcite type crystal having an average particle diameter of 0.4 μm was added instead of the spherical silica. , A transesterification reaction and a polycondensation reaction to obtain polyethylene terephthalate G having an intrinsic viscosity of 0.63.

Polyethylene terephthalate H Instead of spherical silica, monodispersed vaterite-type goethite-like calcium carbonate having an average particle diameter of 0.4 μm is added to 0.6 g of calcium carbonate.
A transesterification reaction and a polycondensation reaction were performed in exactly the same manner as for polyethylene terephthalate F, except that the parts by weight were added.
Polyethylene terephthalate H having an intrinsic viscosity of 0.62 was obtained.

Polyethylene terephthalate I Instead of spherical silica, cubic calcium carbonate of monodispersed calcite type crystal having an average particle diameter of 0.4 μm
A transesterification reaction and a polycondensation reaction were performed in exactly the same manner as for polyethylene terephthalate F, except that the parts by weight were added.
Polyethylene terephthalate I having an intrinsic viscosity of 0.62 was obtained.

Polyester terephthalate J Transesterification and polycondensation were carried out in exactly the same manner as for polyethylene terephthalate F except that 0.6 parts by weight of dispersed γ-type aluminum oxide having an average particle diameter of 0.08 μm was added instead of spherical silica. The reaction was performed to obtain polyethylene terephthalate J having an intrinsic viscosity of 0.60.

Polyethylene terephthalate K In place of spherical silica, 0.6 parts by weight of a dispersed kaolin having an average particle diameter of 0.4 μm was added, and the transesterification reaction was performed in exactly the same manner as for polyethylene terephthalate F.
A polycondensation reaction was performed to obtain polyethylene terephthalate K having an intrinsic viscosity of 0.62.

Polyethylene terephthalate L In place of spherical silica, heat-resistant organic particles mainly composed of monodispersed polystyrene having an average particle diameter of 0.4 μm are used.
A transesterification reaction and a polycondensation reaction were carried out in exactly the same manner as for polyethylene terephthalate F except that 6 parts by weight were added.
I got

Polyethylene terephthalate M A transesterification reaction and a polycondensation reaction were carried out in the same manner as in polyethylene terephthalate B except that the addition amount of the solid content of calcium carbonate B was changed from 0.7 parts by weight to 5 parts by weight. 0.58 polyethylene terephthalate M was obtained.

The measuring methods and definitions of various physical properties and characteristics in Examples and Comparative Examples are as follows. (1) Average particle size and particle size distribution Centrifugal sedimentation type particle size distribution analyzer (SA-CP manufactured by Shimadzu Corporation)
Integrated volume fraction 5 in equivalent spherical distribution measured by type 3)
The particle size of 0% was defined as the average particle size. (2) Young's modulus (tensile modulus) Tensile tester Intesco Model 2 manufactured by Intesco Corporation
Using a Model 001, a test film having a length of 300 mm and a width of 20 mm was pulled at a strain rate of 10% / min in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH. Using the linear portion, Young's modulus (E) was calculated by the following equation. E = Δσ / Δε (where Ε, Δσ, and Δε are Young's moduli (kg
/ Mm ² ), the stress difference due to the original average cross-sectional area between two points on the straight line, and the strain difference between the two points.) (3) Runnability Measured by the slipperiness of the film. The slipperiness was measured by winding a film around a fixed hard chromium-plated metal roll (diameter 6 mm) and contacting it at an angle (θ) of 135 °, 53 g
A load of (T ₂ ) was applied to one end, the load was run at a speed of 1 m / min, and the resistance (T ₁ , g) at the other end was measured.

[0057]

(Equation 1)

(4) Abrasion characteristics A film was wound around a fixed hard chrome fixing pin having a diameter of 6 mm and contacted at an angle of 135 °, and the speed was 10 m / mi.
n, the film was run over 1000 m under a tension of 200 g, and the amount of abrasion white powder adhering to the pins was visually evaluated and evaluated according to the following ranks. Rank A: Not attached at all Rank B: Attach a small amount Rank C: Attach a small amount (more than Rank B) Rank D: Attach very much

(5) Scratch Resistance The polyester film cut to a width of 10 mm is run on a plastic pin while rubbing once at a tension of 100 g, a winding angle of 90 ° and a running speed of 150 m / min. Then, aluminum was deposited on the friction surface, and the amount of scratches was visually determined by a microscopic photograph of the friction surface, and the friction was classified as follows. 1: No scratches are recognized 2: Slight scratches are recognized but extremely small 3: A small amount of scratches is recognized 4: A large amount of scratches are recognized The obtained polyester film is ranked 1 or 2 as described above. If there is, there is no problem in practical use.

(6) Film winding characteristics The quality of roll misalignment, wrinkling, winding appearance, etc. during the winding operation of the polyester film was comprehensively judged.

(7) Magnetic Tape Characteristics First, a magnetic tape was manufactured. That is, the magnetic fine powder 20
0 parts by weight, polyurethane resin 30 parts by weight, nitrocellulose 100 parts by weight, vinyl chloride-cellulose acetate copolymer 10 parts by weight, lecithin 5 parts by weight, cyclohexanone 1
After mixing and dispersing 00 parts by weight, 100 parts by weight of methyl isobutyl ketone, and 300 parts by weight of methyl ethyl ketone in a ball mill for 48 hours, 5 parts by weight of a polyisocyanate compound was added to form a magnetic paint, and after applying this to a polyester film, the paint was Before being sufficiently dried and solidified, it was magnetically oriented and then dried to form a magnetic layer having a thickness of 2 μm.
Next, using a five-stage super calender composed of a mirror-finished metal roll and a polyester-based composite resin roll, a roll temperature of 85 ° C., a linear pressure of 250 kg / cm,
Under the condition of a running speed of 80 m / min, the above magnetic tape 5
000 m was repeatedly run seven times, and the amount of white powder adhering to the resin roll was visually evaluated and evaluated according to the following ranks. ○: Almost no adhesion of white powder on resin roll △: Very slight adhesion of white powder observed ×: Adhesion of white powder clearly observed

After slitting the magnetic tape to 1/2 inch width, the following magnetic tape characteristics were evaluated at normal speed by an NV-3700 video deck manufactured by Matsushita Electric. (I) VTR head output The VTR head output at a measurement frequency of 4 MHz was measured by a synchroscope, and the relative value was shown in decibels with the blank set to 0 decibel (dB). (Ii) Number of dropouts A video tape on which a signal of 4.4 MHz was recorded was reproduced, and the number of dropouts was measured for about 20 minutes with a dropout counter manufactured by Okura Industry Co., Ltd., and converted into the number of dropouts per minute. .

Example 1 The above-mentioned polyethylene terephthalates (A), (E), and (F) were uniformly mixed at a predetermined weight ratio so that the added particles had the concentrations shown in Table 1, and dried by a conventional method. Thereafter, the resultant was melt-extruded at 290 ° C. to obtain an amorphous sheet, 3.5 times at 110 ° C. in the sheet flow direction (longitudinal direction), and 3.times.
The film was stretched 5 times, further stretched 1.08 times in the longitudinal direction at 130 ° C., and heat-treated at 220 ° C. for 3 seconds to obtain a film having a thickness of 15 μm. Table 3 shows the properties of the film thus obtained. Further, a magnetic layer was applied to the obtained film to obtain a magnetic tape, and its characteristics were measured.

Examples 2 to 10 The above-mentioned polyethylene terephthalates (A) to (M) were uniformly mixed at a predetermined weight ratio so that the added particles had the concentrations shown in Table 1, and dried by a conventional method. A film having a thickness of 15 μm and a magnetic tape using the same were obtained in the same manner as in Example 1. Tables 3 and 4 show the properties of the film and the magnetic tape thus obtained.

Comparative Examples 1 to 10 The above-mentioned polyethylene terephthalates (A) to (M) were uniformly mixed at a predetermined weight ratio so that the added particles had the concentrations shown in Table 2, and dried by a conventional method. Thereafter, a film having a thickness of 15 μm and a magnetic tape using the film were obtained in the same manner as in Example 1. Tables 5 and 6 show the properties of the film and the magnetic tape thus obtained.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

[Table 6]

[0072]

As described above, the biaxially oriented polyester film of the present invention is excellent in abrasion resistance, scratch resistance and running properties and is useful as an industrial material such as a base film for a magnetic recording medium. , Its industrial value is high.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 5/704 G11B 5/704 // B29K 67:00 105: 16 B29L 7:00 (56) References JP-A-5-294616 (JP, A) JP-A-4-292414 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 67/00-67/08 C08K 3/00-13/08 B29C 55 / 12 C08J 5/18 G11B 5/704

Claims (3)

(57) [Claims] 1. A polyester film comprising an acid component mainly comprising an aromatic dicarboxylic acid and a glycol component, wherein ultrafine calcium carbonate particles having the following physical properties (a) to (d) are contained in an amount of 100 to 20,000 ppm. A biaxially oriented polyester film, comprising: (A) In the shape examined by an electron micrograph, a value of 0.
At least 5% by weight of needle-like calcium carbonate particles having an aspect ratio (ratio of major axis / minor axis) of 2 or more, comprising primary particles of 0025 to 0.1 μm connected in a chain, is contained. 005 μm ≦ DS1 ≦ 0.5 μm (c) 0.0025 μm ≦ DS2 ≦ 0.1 μm (d) 0.01 μm ≦ DP1 ≦ 0.4 μm, where DS1: average particle of major axis of ultrafine calcium carbonate examined by electron micrograph Diameter (μm) DS2: Average particle diameter (μm) of ultra-fine calcium carbonate as determined by electron micrograph DP1: Light transmission type particle size distribution analyzer (SA- manufactured by Shimadzu Corporation)
In the particle size distribution measured using CP3), the particle diameter (μ
m). 2. The biaxially oriented polyester film according to claim 1, wherein the calcium carbonate ultrafine particles are calcium carbonate ultrafine particles prepared by disintegrating vaterite crystal-type calcium carbonate. 3. An alcohol system containing ultra-fine particles of calcium carbonate containing at least one selected from chlorides of zinc, aluminum and copper, a calcium compound such as calcium hydroxide, calcium oxide and calcium chloride, and carbon dioxide gas. By aging a calcium carbonate matrix of vaterite crystals obtained by reacting a carbonate or carbonate such as sodium carbonate and ammonium carbonate, ultrafine calcium carbonate particles obtained by disintegrating the calcium carbonate matrix of the vaterite crystals are obtained. 2. The biaxially oriented polyester film according to claim 1.