JPS62223239A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the titled film having a low content of coarse particles and a smooth surface and excelling in sliding property and abrasion resistance, by adding a specified inorganic fine particles surface-treated with a silane coupling agent to a polyester. CONSTITUTION:The surfaces of inorganic fine particles (e.g., zeolite) having an average particle diameter of 0.1-2mum, wherein at least 0.5wt%, based on the entire particles, particles have a diameter >=5mu, and a specified surface area >=120m<2>/g are treated with a silane coupling agent (e.g., gamma- glycidoxypropyltrimethoxysilane) to obtain fine inorganic particles of a specified surface area of 30-100m<2>/g. A polyester in which at least 80mol% of the main repeating units comprise ethylene terephthalate, obtained by reacting an aromatic dicarboxylic acid (dimethyl ester) with a glycol containing 0.005-1wt% said fine inorganic particles, is formed into a film, and this film is biaxially oriented in the lengthwise and crosswise directions at an area ratio >=4 to obtain a biaxially oriented polyester film for magnetic recording low in the occurrence of defects such as drop-out.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an easily slippery co-axis oriented polyester film with a low content of coarse particles and extremely few falling particles. When the polyester film of the present invention is made into a magnetic tape, it has excellent running durability and less increase in dropouts due to repeated running, so it is suitable as a base film for magnetic tape.

<Prior art> Generally, polyesters such as polyethylene terephthalate are used for textiles, molded products, magnetic tapes, photographs, etc. due to their excellent physical and chemical properties.
It is widely used in a variety of applications, including film for capacitors and packaging. When used for these films, their lubricity and abrasion resistance are major factors that determine the workability of the film manufacturing process and processing process for each application, as well as the quality of the product. .

In particular, when applying a surface active magnetic layer of polyester/I/film and using it as a magnetic tape, the coating roll and tension control during application of the magnetic layer17), l)' The effects of abrasion and friction are extremely large, and scratches and white powdery substances often occur on the film surface. In addition, when the web is slit after applying the magnetic layer and used as an audio, video or computer tape, significant friction and abrasion occurs between guide parts, playback heads, etc., causing scratches and film damage. The precipitation of white powdery substances due to surface abrasion, etc. is often a major cause of missing magnetic signals, that is, dropouts. In general, a method of imparting slipperiness to polyester film is to mix insoluble fine particles with polyester to form fine irregularities on the surface of the film.Specifically, when manufacturing polyester, In addition, the so-called external particle method involves adding inactive fine particles to polyester such as kaolinite, calcium carbonate, titanium dioxide, silica, and Merck.
There is an internal particle method in which either a carboxylic acid component or a phosphorus compound is reacted with a metal compound to form fine particles during the polyester production reaction. Among the above λ methods,
In the internal particle method, polymerization conditions must be strictly controlled in order to keep the amount and particle size of the precipitated particles constant at all times.In contrast, the external particle addition method requires strict control of the concentration and particle size of the inert particles to be added. It is widely used because the diameter can be controlled relatively easily.

<Problems to be Solved by the Invention> In the external particle addition method, the larger the size of the added particles, the greater the effect on lubricity, but magnetic tape, Particularly in high-density recording applications such as video, it is known that if the particle size is large, the output decreases and signal dropout occurs due to the inclusion of coarse particles.

For this reason, it is desirable that the unevenness on the surface of the film be as fine as possible. Therefore, in order to satisfy such characteristics, it is desirable to precisely control the particle size of externally added particles and add fine particles.

However, as the particle size decreases, the specific surface area increases and at the same time the surface activation energy increases.
There are problems in that secondary agglomeration occurs and coarse particles increase. In addition, particles with a large specific surface area have a large ability to disperse water molecules, and for this reason, it has been found that drying the raw resin is extremely difficult. When normal drying conditions are used, resins containing particles with such a large specific surface area will have a large drop in viscosity during the extrusion process, deteriorate the mechanical properties of the film, and have poor operational stability. There is a problem.

The present invention provides a base film for magnetic recording that has a flat surface necessary for high-density magnetic recording, has excellent lubricity and wear resistance, has fewer defects such as dropouts, and can be produced stably industrially. The purpose is to provide.

Means for Solving the Problems> The gist of the present invention is that a polyester whose main repeating unit is ethylene terephthalate has a particle surface treated with a silane coupling agent, and has an average particle diameter of o, i-1μ.
Co-axial stretching containing 0.00j-/multiply of inorganic particles with a specific surface area of 30-/00 i/i and particles with a particle size of 5μ or more relative to all particles adjusted to less than 0.00j-/m. Exists in polyester AI film.

The coaxially stretched polyester film of the present invention has excellent surface smoothness and excellent lubricity, and since particles do not fall off during use, it has the characteristics of significantly less scratches and white powder generation. have. In addition, it has excellent thermal stability in the film manufacturing process, especially in the extrusion process, and can significantly reduce process troubles such as film breakage.
X)! The p-fluctuation is also small, making it extremely useful industrially. The average particle size of the particles in the present invention is 0.7 to -μm, more preferably 0.3 to 8μm. 0.3μ
If it is less than m, the coefficient of friction of the film becomes large and the operability of winding up the film becomes poor. Moreover, if the thickness exceeds 8 μm, the electromagnetic conversion characteristics, especially the output, will be greatly reduced, making it impossible to obtain a high-performance magnetic tape.

If the amount of particles is less than 4, the coefficient of friction of the film will be large and the operability such as winding up the film will be poor, while if the amount exceeds 4, the electromagnetic conversion characteristics, especially the output will be greatly reduced. High performance magnetic tape cannot be obtained.

Furthermore, in the present invention, particles o, je1 of jμ or more
Although it is required that the particle size be adjusted to 6 or less, particles of Sμ or more give large protrusions in the film and cause dropouts when used as a base film for magnetic tape. It is preferable to have as few particles as possible with a particle size of more than jμ, but by reducing the number of particles by weight to less than 0.1%, preferably less than O, the number of dropouts can be reduced to less than 10 particles/min. , to a level that does not pose a problem in practice.

21J- of ethylene glycol etc. containing the above particles
may be added to the polyester manufacturing process at any stage until the initial condensation reaction is completed. Optimal conditions for the timing of addition of this slurry vary depending on the type of fine particles, differences in the polyester manufacturing process, etc., but in short, the slurry should be added under conditions that do not agglomerate the Kagishi particles produced during the polyester manufacturing process.

In the present invention, the polyester film is a polyester in which 10 moles or more of the main repeating units are ethylene terephthalate, and other components that can be copolymerized with this, such as dicarboxylic acids, glycols, and oxycarboxylic acids, are used. A copolymer of less than 20 moles may also be used. The polymer may contain phosphoric acid, phosphorous acid, esters thereof, and stabilizers. As methods for producing the polyester, both 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 are adopted. I can do it. Note that a biaxially oriented film is particularly suitable as the film.

The biaxially oriented film referred to in the present invention may be obtained by rolling or by biaxial stretching (simultaneous biaxial stretching or sequential biaxial stretching may be used).

The degree of orientation is preferably biaxial so that the area magnification in the vertical and horizontal directions is greater than or equal to the magnification. The vertical and horizontal magnifications are particularly preferably 6 times or more. Examples of the inorganic particles in the present invention include zeolite, celite, 7-oasiasite, and mordenite. The specific surface area of these particles is /j
It is known that Orrl/I or higher can be obtained naturally or synthetically and is useful because of its excellent adhesion between the film-coated polymer and the particles (Japanese Patent Application Laid-Open No. 2003-100000, 56-77).
See publication. ] Also, it is known that it is necessary to control the average particle diameter and the content of coarse particles in order to reduce the surface roughness, center line average roughness, and coarse protrusions as a base film for magnetic recording. fP opening group 60!1
See rq37 publication. ).

However, particles with a large specific surface area have a large surface activity and adsorb molecules from the outside world, mainly water molecules. Therefore, when producing a polymer using such particles, the drying conditions / ff of normal polyester raw materials are O'C4I time cannot sufficiently remove the adsorbed water, and the process from melting the raw material in an extrusion manner to extruding it onto a cooling drum causes a significant decrease in viscosity, which causes problems during film production. It was discovered that breakage occurs frequently.

The present inventors focused on the above-mentioned circumstances and, as a result of intensive studies, arrived at the present invention. That is, the specific surface area of the raw particles should be 1/I or more, and the particle size should be 0. / -2 μm, more preferably O
, J~1. -μm particles whose specific surface area is controlled to 30 to 1oo7FL''/I using a silane coupling agent, the polymer melted and formed into a film using an extruder using a normal drying process. The decrease in viscosity was almost at the normal level, and operation was possible without any breakage.The particles in the polymer were compatible with the polymer, did not fall out of the film, and there were few scratches during film running.

The silane coupling agents used in the present invention are r-glycidoxyglobiltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β
-methoxyethoxy)silane, r-methacryloxypropyltrimethoxysilane, N-β(aminoethyl)r
Examples include -aminopropyltrimethoxysilane, N-β(aminoef)W)r-aminopropylmethyldimethoxysilane, r-chloropropyltrimethoxysilane, and r-mercaptoglobiltrimethoxysilane.

Although the treatment method used in the present invention is a wet method, it is only necessary to select reaction conditions that cause less re-agglomeration of particles, conditions that selectively couple to particles in an ethylene glycol slurry, and silane coupling directly to particles. A dry method in which the ring agent is sprayed and then heat-treated, a spray method in which hot particles are sprayed, etc. can be used.

(Examples) Hereinafter, the present invention will be explained in more detail by way of examples.
The present invention is not limited to these embodiments unless the scope thereof is exceeded. The methods for measuring the properties of particles and films are as follows.

(Measurement of the average particle size of 11 inorganic fine particles and coarse particles) The particles were enlarged and photographed using an electron microscope, and the average particle size was determined using a photographic method.The same method was used for particles with a particle size of jμ or more. It was measured and the ratio was determined.

(2) Specific surface area of inorganic particles Measured by the so-called B11IfT method determined from the amount of nitrogen gas adsorbed at the temperature of liquid nitrogen.

(3) Average protrusion height R & Koita Research Institute ■ Using a back surface roughness measuring machine model sm-, 7F, it was carried out according to the method described in T Engineering 8 BO40/-/974. The measurement conditions were as follows: stylus diameter μm, stylus pressure 30 mm, cut-off value go μm 5611J constant length, jllml/One point was measured, the maximum and minimum values were cut, and the average value of 70 points was shown.

(4) Intrinsic viscosity measurement and viscosity reduction rate Sample-009 is phenol/tetrachloroethane = J
O/! The mixture was added to 0rnl of a mixed solution of No. 10 and dissolved by heating at about 10°C for 1 hour, and then measured at 30°C. The viscosity reduction rate was determined using the following formula.

(5) Evaluation of scratches on the film surface A spot light was applied to the film surface in a dark room, and the degree of unevenness was visually determined.

Ranks; unevenness is visible on the entire surface of the film.

Rank Δ: Scratches are seen in a part of the film.

2 ink ○: Almost no unevenness is observed on the film surface.

(6) Evaluation of abrasion resistance Using the tape abrasion evaluation machine shown in Figure 7, the width was 101! □o,? A fixed bottle (diameter A 1111
The amount of abrasion powder adhering to s Material SU8 Hirojo-, TJ, Finish 0O-8) was visually evaluated and divided into a-). The running speed of the film is 11. dam/min and the tension is (1
1), the initial tension is 30011, and the angle θ is /
J j'.

Rank A: No adhesion observed.

Rank B: Very slight adhesion is observed, but there is no problem in practical use.

2 ink C: The amount of adhesion is a little large and it will shift which becomes a problem if used for a long time.

Ranks: Difficult to use practically due to large amount of adhesion.

(7) Evaluation of resistance to protrusion deformation When winding the film, a certain amount of particles of 11Clysμ was intentionally added, the number of turns required for the partial bulge in the film to disappear was counted, and the film was divided into three ranks: A, B, and O. The one with the smallest number of windings, that is, the one with excellent anti-protrusion deformation properties, was designated as A.

(8) Evaluation of the number of coarse protrusions Aluminum vapor deposition was applied to the film surface, and 2:27 y
Measurement was performed using a two-beam method using an l-7' thiaod interference microscope. The protrusion (protrusion height □, lrlμ or more) exhibiting interference fringes of 3rd order or higher at the measurement wavelength j II Onm is 100cr/
The number of coarse projections was determined over an area of l.

(9) Magnetic Tape Characteristics First, the following magnetic paint was applied to a polyester film to form a magnetic layer so that the film thickness after drying was only a fraction of the thickness.

HII, 200 parts by weight of ultrafine magnetic metal powder, urethane:
y resin Jot:tm, 10 parts by weight of nitrocellulose,
Salted salmon vinyl copolymer ioz part, lecithin 3 parts by weight, cyclohexanone ioo parts by weight, methyl isobutyl y ketone 10 parts
0 parts by weight and JOOjjL* parts of methyl ethyl ketone were mixed and dispersed in a ball mill for a tit time of 5 parts by weight of a lipolyincyanate compound to make a magnetic paint, and after applying this to a polyester film, before the paint was sufficiently dried and solidified, it was magnetically oriented. It was then dried. Further, this coated film was subjected to surface treatment using a supercalender, and was slit to a width of 771 inches to prepare a videotape. This videotape was repeatedly run 00 times on a Matsushita Electric WNV-3700 video deck, and the following magnetic tape characteristics were evaluated.

o VTR head output: The VTR head output at a measurement frequency of MHz was measured using a synchroscope Kj, and the sample of Example 3 in Table 1 was set to 0 (dβ), and its relative value was expressed in decibels (d/y).

Number of dropouts: Play back the video tape that recorded the 9-megahertz signal, measure the number of dropouts at /jμ5ec--〇dβ for 10 minutes using a dropout counter manufactured by Daigon Industries ■, and calculate the dropout for 1 minute). It was converted into the number of outs (77 minutes).

Example/ (1) Adjustment of particles Zeolite with an average particle diameter O0 of 1μ is mixed with ethylene glycol l! After mixing with 600 g of coke, it was subjected to a high-pressure homogenizer (Gowlin homogenizer M-/! model, manufactured by Manton-Bowlin Co., Ltd., USA), and the pressure was 100kli/c.
al and dispersion processing was performed for the number of processing times. The obtained slurry was centrifuged (Super Decanter P manufactured by Tomoe Kogyo).
-66θ) to obtain a slurry with an average particle diameter of 0.49 μm and a ratio of large particles of 34 m or more in each slurry, o and to.

Furthermore, the slurry was filtered using a filter with pores of 3μ, and the proportion of large particles with an average particle diameter of o, byμ7gjμ or more was 0.
．． A 10-layer slurry was obtained.

(2) Add 700 parts of r-glycidoxyglobiltrimethodF to the slurry solution prepared in (1) for silane coupling treatment method.
,,)HOHa0OiHs81(OCRs)s)
70 parts of 256 aqueous solution was added, mixed and stirred, heated to 90''C and treated for 30 minutes, and then water was removed under reduced pressure.

When the specific surface areas of (1) and (2) were measured, ig.

m/11 and 1. It was Oyj/i.

(3) Production of polymers and films 700 parts of dimethyl tere-7-thalerate, 60 parts of ethylene glycol, and 0.09 parts of magnesium acetate tetrahydrate are placed in a reactor, heated to an elevated temperature, methanol is distilled off, and a transesterification reaction is carried out. After a while from the start of the reaction, the temperature was raised to 30°C, and the transesterification reaction was substantially completed. Then (17
and (2) average particle diameter of 0.49 μm
Weigh out 0.3 part of ethylene glycol slurry of zeolite particles in terms of particle weight, add it during transfer to the polymerization reactor, further add 0.041 part of ethyl acid 7-mole 7-ate, and 0.0 part of antimony trioxide, and heat for a while. Polycondensation was performed to obtain polyester chips. Next, after drying at a temperature of 10° C. for a certain period of time, it was extruded into a sheet at a temperature of 290° C., and an amorphous sheet of 10 μm in size was produced by an electrostatic contact cooling method. Next, this amorphous sheet was stretched by 2 times in the machine direction, 3 times by j in the cross direction, and further 1 time in the machine direction to obtain a coaxially stretched film having a thickness of io μm and reinforced in the machine direction. Table 1 shows the properties of the obtained film and the properties after it was made into a magnetic tape.

Example In Example 1, the average particle diameter of the zeolite particles O,j
ff /jm, specific surface area tqsrr (/l) was treated in the same way, and the specific surface area was added with '/ld/1, and a U-axis stretched film was obtained in the same manner as in Example 1. Characteristics The evaluation results are shown in Table 1.

Example 3 In Example/, the average particle diameter of zeolite particles O, +S
μm, specific surface area of iogo/I was treated in the same manner, and a specific surface area of 97 m''/I was added to obtain a coaxially stretched film in the same manner as in Example 1. Evaluation of properties. The results are shown in Table 1.

Comparative Example 1 A -axially stretched polyester film was obtained in the same manner as in Example 1, except that the silane coupling treatment of the zeolite particles in Example 1 was omitted. The results are shown in Table K1.

Comparative Example - An axially stretched polyester film was obtained in the same manner as in Example, except that the silane coupling treatment of the zeolite particles was not carried out. The results are shown in Table 1.

Comparative Example 3 0.3 parts by weight of silica particles having an average particle diameter of 10 μm and a specific surface area of 10 μm and a specific surface area of 10 μm and 11 μm were mixed without silane coupling treatment.
A coaxially stretched film was obtained in the same manner as in Example 1. The results are shown in Table 1.

All of the films of Example/-j that meet the requirements of the present invention showed little viscosity decrease during the extrusion process, almost no scratches on the surface of the film during the re-stretching process, and There was no protruding deformation when it was rolled into a roll, and the roll appearance was very good. Furthermore, when actually used as a magnetic tape, there was very little deterioration in characteristics after 100 repeated runs, and there was almost no increase in signal loss (dropouts), making it a highly valuable product from an industrial perspective. . In addition, since the decrease in viscosity was small, there was no breakage during the process, making it suitable for recycling as a recycled product. On the other hand, in Comparative Example 1, unevenness was observed on the film surface, the output was low despite the low roughness, and the increase in dropouts was extremely high.
The product was of inferior value.

Comparative Examples C and J had many scratches on the film surface, had poor abrasion resistance, and had a large increase in dropouts, and were unsuitable as base films for magnetic tapes. In addition, both Comparative Examples/Sco and 3 showed a large decrease in viscosity, making them unsuitable for use as recycled chips in the manufacturing process.

<Effects of the Invention> According to the present invention, it is possible to provide a polyester film suitable for use in magnetic tapes, which has excellent running properties and durability, and has little increase in dropouts due to repeated running.

[Brief explanation of drawings]

Figure 7 is a schematic diagram of the running system for evaluating wear resistance, and (1) in the figure is b*yal's EIUS-tei-〇-, 7JO0-
8 fixed bin with surface finish, (if) is tension pickup. Also, when wrapping the film around the fixed bottle, the angle θ
is / J j'. Applicant: Diafoil Co., Ltd. Agent: Patent attorney: Yo Hase - 1 other person

Claims (1)

[Claims] (1) A polyester whose main repeating unit is ethylene terephthalate, the particle surface of which is treated with a silane coupling agent, an average particle diameter of 0.1 to 2 μm, a specific surface area of 30 to 100 m^2/g, and all particles 5 against
A biaxially stretched polyester film containing 0.005 to 1% by weight of inorganic fine particles having a particle size of μ or more adjusted to 0.5% by weight or less.