JPH01128A - polyester film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polyester film having few large protrusions, excellent slipperiness, and highly improved winding characteristics, abrasion resistance, and uneven scratch resistance.

<Prior art and problems to be solved by the invention> Polyester, represented by polyethylene terephthalate, is used for magnetic recording, capacitors, For packaging, plate making,
It is used as a base material in many fields such as electrical disconnection and photographic film. When polyester is used for these,
Although the required properties differ depending on each application, the universally required property is the film's ease of handling, and to improve this, it is necessary to reduce the slipperiness of the film, that is, the coefficient of friction. .

Also, audio and video have been growing rapidly in recent years.

When a magnetic layer is applied to the surface of the film as a base film for combinators and used as a magnetic recording medium, if the slipperiness and abrasion resistance are poor, friction between the coating roll and the film surface during application of the magnetic layer may occur. And the wear is severe, and scratches are likely to occur on the film surface.

In addition, the film after applying the magnetic layer can be used for audio, video,
Even after processing it into products such as computer tape,
When pulling out, winding up, and operating the reel or cassette, significant friction and abrasion occurs between the guide section, recording and playback heads, etc. of the polyester film, resulting in white powdery substances due to scratches on the surface of the polyester film, etc. is generated, which is often a major cause of missing magnetic recording signals, that is, dropouts.

In order to improve these properties required of a polyester film, a commonly adopted method is to add inactive fine particles to the polyester in order to impart irregularities to the surface of the film.

This method can be broadly divided into two. One method is called the precipitation method, in which one or more metal compounds soluble in ethylene glycol, such as calcium compounds and lithium compounds, are added before and after the transesterification reaction or esterification reaction to make polyester insoluble. This method involves precipitation as fine particles.

Another method that is contrasted with the precipitation method is the addition method, in which inert inorganic particles such as calcium carbonate, calcium sulfate, barium sulfate, kaolin, silica, talc, graphite, carbon black, and titanium dioxide are added. It is known to be added during polyester synthesis or molding. However, although these inorganic particles are usually obtained by grinding or synthesizing natural minerals, it is difficult to avoid the presence of coarse particles or aggregated particles.

If coarse particles or large particles due to agglomeration coexist in the polyester, the filter may be blocked during the extrusion process, or the film may break during film formation.Furthermore, microscopic defects called "fischepui" in the film may cause dropouts and condensers on magnetic tapes. This causes problems such as poor withstand voltage.

Particularly in the field of magnetic tape in recent years, there has been a desire for precision through miniaturization, longer operation times, and higher image quality.

Therefore, it is necessary to make the unevenness on the film surface more uniform and fine.

For this purpose, a method has been proposed in which inert inorganic particles are pulverized and classified in advance to remove coarse particles.

For example, a method is known in which a powder obtained by pulverizing a natural raw stone or a powder obtained by synthesis is further subjected to a dry or wet pulverization treatment, and then a dry or wet classification treatment. Large particles due to agglomeration are
Although it was possible to remove it to some extent, it was not sufficient.

On the other hand, various products of silica particles having different average particle diameters are commercially available. However, even if such silica particles were incorporated into polyester to form a film, the film could not satisfy the above-mentioned strict requirements.

That is, like silica particles, the activity of the particle optical surface is relatively high;
Fine particles tend to form secondary agglomerates and are difficult to disperse in a dispersion medium.

Aggregation also occurs during polyester production.

As a result, the surface roughness of the polyester film becomes non-uniform, reducing the product value of the film.

Generally speaking, the larger the particle size of these particles in a polyester film, the greater the effect of improving slipperiness. However, especially for precision applications such as audio, video, and computer applications, the particles themselves are large and coarse. Since the mixture of particles and large particles due to aggregation can cause dropouts, the particles contained in the polyester film need to be as uniform and fine as possible.

However, the current situation is that it is extremely difficult to simultaneously satisfy these contradictory characteristics.

Means for Solving the Problems> The present inventors have discovered that as the precision of magnetic recording tapes for audio, video, computer, etc. is further promoted, improvements in slipperiness, abrasion resistance, and surface defects are increasingly required. In light of the growing situation in which film production is becoming more common, the film has a smooth surface, excellent slipperiness and abrasion resistance, and is less prone to defects such as dropouts.
A magnetic recording film with excellent abrasion resistance and scratch resistance was discovered, and the present invention was achieved.

That is, the gist of the present invention is that the average particle diameter obtained by the hydrolysis reaction and condensation reaction of alkoxysilane is 0.07 to
/, 0 μm and defined by the following formula (1) [cL10
/d90] substantially amorphous spherical silica fine particles (fine particles (A)) having a value in the range of /, /~2.7 from 0.01 to
The following formula (
2) The (D2/D+] value defined in /, /~da, O
A polyester film characterized by containing o, ooz-o, s of fine particles (B) of

・・・・・・(1) Hereinafter, the present invention will be explained in detail.

The polyester referred to in the present invention refers to aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene, and 6-dicarboxylic acid or esters thereof, ethylene glycol, diethylene glycol, tetramethylene glycol,
It is a polyester that can be obtained by polycondensation with a glycol such as neopentyl glycol.

This polyester can be obtained by direct polycondensation of aromatic dicarboxylic acid and glycol, or by polycondensation after transesterification of aromatic dicarboxylic acid dialkyl ester and glycol, or by polycondensation of aromatic dicarboxylic acid diester. It can also be obtained by methods such as forcing.

Polyethylene terephthalate' is a typical example of such polymers. Examples include yNIJ ethylene, 6-naphthalate, and the like. This polymer may be a homopolymer or may be copolymerized with a third component.

In any case, in the present invention, a polymer having 0 mol % or more of ethylene terephthalate units and/or ethylene-6-naphthalate units is preferred.

The intention of the present invention is that the average particle size is 0.01~/, Q
) ta spherical silica fine particles are used as fine particles (A), and specific amounts of fine particles (B) having an average particle diameter of i, i-u, and o times the fine particles (A) and having a Mohs hardness of q and o or less, respectively. The film is added to improve the slipperiness, abrasion resistance, and scratch resistance of the film.

The spherical silica fine particles used in the present invention are obtained by a hydrolysis reaction and a condensation reaction using an amine catalyst using an alkoxysilane as a starting material.

As an alkoxysilane compound ((3nHzn+tO
)481...(n = / = g), and as specific compounds, compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane are preferably used. As a hydrolysis reaction and condensation reaction catalyst, ammonia, trimethylamine, tetraethylammonia aqueous solution,
Although urea etc. can be used, an ammonia aqueous solution is preferable.

For example, the method for synthesizing spherical silica particles is as follows. That is, a solution (A) is prepared by dissolving tetramethoxysilane in a methanol solvent, and a solution (B) is separately prepared by dissolving an ammonia aqueous solution in a methanol solvent. Both solutions are kept at a predetermined temperature, e.g.
After maintaining the IW solution (B) at
Add A).

Then, after holding at a predetermined temperature for several hours, it is centrifuged, washed with alcohol as a solvent, and then dispersed in ethylene glycol, or after the reaction is completed, ethylene glycol is added to the suspension of silica particles, and then distilled. Alternatively, a method may be used in which water is removed from excess ammonia and alcohol.

In any case, it is preferable that the spherical silica fine particles of the present invention are finally prepared as an ethylene glycol slurry.

The concentration of spherical silica fine particles in the ethylene glycol prepared as described above is preferably less than 70% by weight. (IO
If it is less than % by weight, agglomeration in ethylene glycol slurry and generation of aggregated particles when added during polycondensation reaction are within a range that poses no practical problem. More preferably, the content is less than 20% by weight, and the O,S weight is preferably at least 20% by weight.

The concentration of spherical silica particles in ethylene glycol is 1I
If OTi+i% is exceeded, the formation of agglomerates is undesirable when added during aggregation and polycondensation reactions in ethylene glycol slurry. Further, if it is less than 0.95% by weight, the amount of ethylene glycol used becomes excessive, which is economically disadvantageous, and is not preferred.

The characteristics of the spherical silica fine particles obtained by the hydrolysis and condensation method of alkoxysilane in the present invention are that they are spherical in shape and have extremely uniform particle diameters. That is, the particle size distribution of the particles is determined by an electron micrograph, the number of particles of each particle size is integrated, and the particle sizes representing 70% and 90% of the integrated number are defined as dlo and dqo, and ('3
-10/d90 ] is required to be in the range of 8/ to 2.7. Preferably, the value of [dlQ/dqθ] is in the range of /, / to 2.3.

[d10/d? If the value of [O] exceeds λ, 7, it means that the particle size distribution is broad, which is not preferable because it becomes difficult to control the surface roughness when formed into a film, and the number of coarse particles increases. In addition, it is actually extremely difficult to industrially obtain particles having a particle size distribution in which the value of [d10/cL90] is below zero.

The average particle diameter of the spherical silica fine particles as the fine particles (A) used in the present invention must be 0.07 to 7.0 μm, and more preferably θ,OS to 0.2 μm. If it is less than 0.0/μm, the effect of improving the surface properties and slipperiness of the film will not be sufficient. In addition, recent high precision,
In response to the demand for higher quality, if the surface roughness of the film exceeds i,oμm, the surface roughness of the film becomes too large, and when it is made into a magnetic tape, the mixture of large particles that causes dropouts and decreases in output increases, and the film quality deteriorates. This is not preferable because it lowers the temperature.

The content of fine particles (A) in the polyester film is 0.
It is necessary to set it to O/~3.011i, 11%, and more preferably, it is 0.05~/, 0% by weight.

The content of fine particles (A) in the polyester film is 0.
If 0/weight i% is not grooved, the effect of improving the slipperiness and abrasion resistance of the obtained film is insufficient.

If it exceeds 3.0% by weight, the surface roughness of the film will become too large, and the mixture of large particles will increase, which will cause a decrease in output and dropouts when used as a magnetic tape.
This is not preferred because the film quality deteriorates.

Further, the Mohs hardness of the fine particles (B) used in the present invention must be θ or less. If the Mohs hardness of the fine particles (B) exceeds y or o, scratches will occur between the films during winding and winding up of the film in the film forming process, and scratches will occur during the calendaring process after magnetic non-coating. This is not preferable because it causes various problems such as scratches on the roll. Further, the average particle diameter of the fine particles (B) is the average particle diameter D1 of the fine particles (A).
), the [D2/D1] value expressed by the average particle diameter D2 is /
, /-11,0.

If the (D2/Dt) value is less than /, 1, the effect of improving the abrasion resistance and winding characteristics when made into a film will be insufficient, which is not preferable.In addition, if the [D2/D1] value exceeds φ・O, This is not preferable because the surface roughness of the film becomes too large and the presence of large particles that cause dropouts increases, resulting in a decrease in film quality.

The content of fine particles (B) in the polyester film is O1
θ05~o, s TL JL%, more preferably 0.0/~0.2% by weight O The content of fine particles (B) in the film is 0.005% by weight If it is less than that, the effect of improving the abrasion resistance and winding properties when made into a film will be insufficient, so it is not preferable.

Further, the content of fine particles (B) is 0. ! If it exceeds r% by weight, the interfacial roughness of the film will increase the inclusion of large particles that cause dropouts, which will deteriorate the film quality, which is not preferable. Further, the amount ratio of the fine particles (B) to the fine particles (A) is preferably in the range of o, oog to o, r,
More preferably, it is in the range of 0.0/ to θ,/. As mentioned above, the polyester film of the present invention is characterized by having spherical silica fine particles having a specific particle size, which is substantially amorphous, with an extremely sharp particle size distribution and containing no coarse particles, and a Mohs hardness of Hiro, Q. In the following, particles having a specific particle diameter are used in specific amounts. In other words, a polyester film containing only fine spherical silica particles with a sharp particle size distribution, containing almost no coarse particles, has fewer dropouts due to coarse protrusions when used as a magnetic tape, and has good slip properties. Although it has excellent properties, silicon dioxide such as spherical silica fine particles has a high Mohs hardness and is hard, so it is difficult to wind up the film in the film forming process and due to friction between the films during winding. Although there are problems such as the occurrence of scratches and the occurrence of scratches on the resin roll in the calendering process after coating the magnetic layer, the gist of the present invention is to use spherical silica fine particles and a Mohs hardness of y, o or less. Only when these particles coexist, the excellent properties of the fine particles are not impaired, and the abrasion resistance, which is a problem of the fine particles, is improved, which is an extremely excellent effect that cannot be achieved by using the fine particles alone. We have discovered a fact that can be put to good use.

Spherical silica fine particles (A) and particles (
B) can be added to the polyester at any stage in the polyester manufacturing process, but it is preferably added after the transesterification or esterification reaction and before the polycondensation. Furthermore, known methods can be employed for polycondensation of polyester. For example, one or more of antimony compounds, glumanimeum compounds, titanium compounds, etc. are used as catalysts for the polycondensation reaction, and the reaction is allowed to proceed by heating to about 230 to 300° C. and distilling off ethylene glycol under reduced pressure. In addition, when forming a film, a known film forming method 1 is performed, for example, after melting and extruding polyester chips into a film at 270 to 300°C, g.

After cooling and solidifying at ~70°C to form an amorphous sheet, it is sequentially biaxially stretched or simultaneously biaxially stretched vertically and horizontally /60-coqo
Methods such as heat treatment at ℃ (for example,
The method described in Publication No. t can be adopted.

The polyester film according to the present invention can be used, for example, as a base film for magnetic recording media such as magnetic tapes and floppy disks, as well as for capacitors, photolithography, electrical disconnection, thermal transfer, packaging, and transfer marks. It is extremely useful as a base film for various fields such as gold and silver threads.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to the following examples unless the gist of the invention is exceeded.

The various physical properties and characteristics in the examples were measured and defined as follows. Further, in the examples, "parts" and "%" mean "parts by weight" and "% by weight", respectively, unless otherwise specified.

(1) Average particle size The diameter of approximately 10θθ particles is measured using a photographic method using electron microscopy deflection, and a value of 30% of the uniform sphere diameter distribution (weight'i standard) is used.

(2) Particle size distribution, the particle size at 90% is defined as (L90), and the ratio (c
The value of io15o) indicates the sharpness of the particle size distribution.

(3) Intrinsic viscosity [η] Polymer/fl to phenol/tetrachlorethane=j
Dissolve in a mixed solvent of 100 - O/j O (weight ratio) and measure at 30°C.

(4) Surface roughness of film J Engineering E3BOAθ/-/Def6 Measured by the method described above. For measurement, surface roughness measuring machine model 5 manufactured by Koita Institute was used.
Using Fi-JF, the stylus diameter was μm.

Center line average roughness (Ra) measured under the conditions of stylus load 30■, cutoff value 0.0, n1 measurement length -, t mm
Display in .

(5) Sliding property of film Represented by friction coefficient, friction coefficient is ASTM D-1tt
The measurement was carried out using a method that was modified so that it could be measured using a tape-shaped sample in accordance with TI. The size of the sample during measurement is width/J
JI, length/, t 0111, tensile speed is 20H
It is y7min. Measured temperature = 1-2℃, humidity 6! ±j
% atmosphere.

(6) Abrasion properties (evaluation of white powder) The film was run over one length using the running system shown in Figure 1, and the amount of wear attached to the hard chrome fixed bottle of Am96 shown in (1) was visually evaluated.

It doesn't stick at all. ...Songs...◎Slight adhesion.・・・・・・・・・・・・・・・・・・・・・
・○Amount of adhesion is large.・・・・・・・・・・・・・・・
・・・・・・・・・△Adheres to the entire surface.・・・・・・・・・
・・・・・・・・・・・・×(7) Winding characteristics When the film was wound into a roll, the appearance of the roll different surface and the roll end surface was evaluated as follows.

Rolls with almost all wrinkles and shibb-like defects on the roll surface and whose end faces are even.
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・○ There are almost no wrinkles on the roll surface, but there are some shib-like defects, and the roll end surface is slightly uneven ・・・・・・・・・・・・...
・・・・・・・・・・・・・・・・・・ △ Rolls with wrinkles on the surface or roll end faces that are uneven ・・・・・・・・・・・・
...×(8) Number of coarse protrusions Aluminum was deposited on the surface of the film and measured using a two-beam method using an interference microscope. The number of protrusions exhibiting third-order or higher interference fringes at the measurement wavelength O, j1 μm is shown in terms of -jcd.

(9) 230±10^ on the surface of a polyester film with abrasion resistance of 15 μm
A thick vacuum-deposited aluminum film with a width of 3! Cut a slit into the crane and attach it to the moving table with the aluminum evaporated side facing up. The ends of test films of the same width were fixed and overlapped on this aluminum vapor-deposited surface, and a load of 11//4 cd was applied on top of the test films, and the moving stage was moved to λO
Moving at a speed of 2V'min, the aluminum evaporated surface and the test film are rubbed against each other from SO to tOB. At this time, the amount of scratches on the aluminum vapor-deposited surface was expressed in total light transmittance (%) using a Nippon Denshoku Co., Ltd. Heldometer NDH-CooD. The greater the amount of scratches, the higher the total light transmittance.

αOm Composite Evaluation Based on the evaluation results described above, it was determined whether or not it could be put to practical use in base films for magnetic recording media, etc.

Practical Northern Times・・・・・・・Song・◎、○Practical use or not・・
・・・・・・・・・・・・・△、×Example/ (Method for synthesizing spherical silica particles) Tetramethylsilane, yo, 4tg was dissolved in 100g of methanol and kept at 20°C ( On the other hand, water iiog was added to methanol tank QOg to liquid A, and 2t% ammonia aqueous solution 21139 was added and mixed, and the mixture was kept at 0℃/(B
liquid). Next, a stirring device was attached to Solution B, and Solution A was added while stirring. Immediately after the addition, a hydrolysis reaction and a condensation reaction occurred, and the inside of the reaction system became cloudy. After adding liquid A and stirring for another 2 hours, add ethylene glycol/0Jf.
i was added and heated under reduced pressure to distill off excess water, methanol, and ammonia to obtain an ethylene glycol slurry containing spherical silica fine particles at a concentration of 10%. After drying the ethylene glycol slurry, a photograph was taken using an electron microscope to determine the average particle diameter and particle size distribution [d10/CL
90] value was calculated. The average particle diameter was 0.0 qμm, and the [d10/dde0] value was /,4tj-, indicating that the particles were extremely uniform in particle diameter.

When the slurry was filtered using a filter having a 3 micron cut-off accuracy, the filter had very good permeability. The particles were used as fine particles (A). Particles (B) were subjected to known wet grinding, wet classification, and filtration treatments to obtain calcium carbonate particles with an average particle diameter of 0.27 μm.

(Manufacture of polyester film) 700 parts of dimethyl terephthalate, 60 parts of ethylene glycol, and o, oq parts of magnesium acetate tetrahydrate were placed in a reactor, heated to raise the temperature, and methanol was distilled off to perform a transesterification reaction. It took t hours from the start of the reaction to raise the temperature to 230°C, and the transesterification reaction was substantially completed.

Next, 0.3% of fine particles (A) with an average particle diameter of 0.09 μm
Ethylene glycol slurry containing
．． After thoroughly mixing and adding 27 μm fine particles (B) o, o% containing ethylene glycol, ethyl acid phosphate O, OII part, antimony dioxide o,
Add o and yz parts and perform polycondensation for a period of time to obtain an intrinsic viscosity of 0.66.
A polyethylene terephthalate resin was obtained.

The obtained polyester resin was heated at 110°C under a nitrogen atmosphere.
After heating and drying for 6 hours, a sheet with a thickness of 130 μm was prepared using an extruder, and then stretched 3 to 7 times in the machine direction and 2 times in the transverse direction. A biaxially stretched polyethylene terephthalate film with a thickness of 10 μm was obtained by heat setting at 2-0° C. for S seconds.

Table 7 shows the properties of the obtained polyester film. As shown in Table 1, the surface roughness, slipperiness, abrasion resistance, and winding properties of the obtained film.

The number of coarse protrusions and the abrasion resistance were extremely good, and were at an extremely satisfactory level as a base film for magnetic recording.

Example--! In Example 1, the mixing ratio of methanol, water, and ammonia aqueous solution in liquid B was changed, and the average particle diameter was o, t Oμm,
Spherical silica fine particles having a (tlto/6qo) value/tA were obtained. A polyester film was obtained in the same manner as in Example 1, except that 0.3% of the fine particles were used as fine particles (A) and 0.02% of bound particles or particles shown in Table 1 were added as particles (B). The properties of the obtained film are shown in Table 1. 1st
As shown in the table, the surface roughness, slipperiness, abrasion resistance, and winding properties of the films obtained in all Examples.

The number of coarse protrusions and abrasion resistance were extremely good, and were at extremely satisfactory levels as a base film for magnetic recording.

Comparative Example/-Example 1. - Characteristics of the film obtained in the same manner as in Example 1 except that the addition of particles (B) was stopped in step 1i.
It was shown to. As shown in Table 1, the surface roughness, slipperiness, abrasion resistance, and number of coarse projections of the film obtained in this comparative example are at satisfactory levels, but the winding characteristics and abrasion resistance are poor, and the magnetic Its commercial value as a recording base film was poor.

Comparative Examples 3 to 6 Average particle diameter o, aottm, (eLto1690) value/
, j-4 spherical silica fine particles as fine particles (A).
3%, and the particles shown in Table 1 were used as particles (B) at 0.0λ.
A film was obtained in the same manner as in Example except that % was added. The properties of the obtained film are shown in Table 1. As shown in Table 1, one particle (B) used in the comparative example has a high Mohs hardness, which falls outside the requirements of the present invention, and therefore has poor abrasion resistance.
Its commercial value as a base film for magnetic recording was poor.

<Effects of the Invention> As detailed above, the polyester film of the present invention has i
, i~a, O times the particle diameter, and Mohs hardness y, o
This is a polyester film containing specific amounts of the following particles. When used as a base film for magnetic recording, a polyester film containing the fine particles has excellent characteristics with significantly less dropout due to surface roughness, slipperiness, and coarse protrusions. Silicon dioxide has a high Mohs hardness of 3.5 to 6.0 (
Because it is hard, it has drawbacks such as winding the film in the film forming process, rubbing water due to friction between the films during winding, and scratches on the resin roll during the calendering process after applying the magnetic layer. However, the gist of the present invention is that only when the fine particles coexist with particles having a Mohs hardness of θ or less, the excellent characteristics of the fine particles are not impaired, and the superior abrasion resistance, which is the drawback of the fine particles, can be improved. We have discovered the fact that these fine particles can exhibit extremely excellent effects that cannot be achieved by using them alone.

[Brief explanation of drawings]

Figure 1 is a diagram showing the running system for evaluating wear resistance.
I) is a 6m91 hard chrome fixing pin, (n) is a tension meter, and θ is /30''.

Claims (1)

[Claims] (1) The average particle diameter obtained by the hydrolysis reaction and condensation reaction of alkoxysilane is 0.01 to 1.0 μm, and the [d10/d90] value defined by the following formula (1) is 1
．． 0.01 to 3.0% by weight of substantially amorphous spherical silica fine particles (fine particles (A)) in the range of 1 to 2.7, and the following formula (2) with a Mohs hardness of 4.0 or less. A polyester film containing 0.005 to 0.5% by weight of fine particles (B) having a [D_2/D_1] value of 1.1 to 4.0. [d10/d90]=Particle diameter when the cumulative number of particles is 10%/Particle diameter when the cumulative number of particles is 90%...
・(1) [D_2/D_1] = Average particle diameter of fine particles (B) / Average particle diameter of fine particles (A)... (2)