JPH02227439A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To provide the film having excellent slipping property, wear resistance and cracking resistance, reduced in the generation of marring or white powder and useful for magnetic tapes, electrical applications, etc., by including a specific amount of polymethylsilsesquioxane powder surface-treated with an organo-silicic compound. CONSTITUTION:The objective film contains 0.001-3wt.%, preferably 0.05-0.5wt.%, of polymethylsilsesquioxane powder (preferably having an average particle size of 0.1-5mum) surface-treated with an organo-silicic compound (preferably hexamethyldisilazane or polyfluoroalkyl group-containing disilazane).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a biaxially oriented polyester film, and more particularly to a biaxially oriented polyester film that has excellent slip properties and abrasion resistance.

[Technical background of the invention and its problems 1 Polyesters such as polyethylene terephthalate have excellent physical and chemical properties and are widely used as films for packaging, photography, magnetic tape, capacitors, etc. . Among the characteristics of these films, the slipperiness and abrasion resistance greatly control the workability of the film's production and processing steps, as well as the quality of the product.

Now, in order to improve the slipperiness and abrasion prevention properties of such a film, a method is generally used in which the surface of the film is provided with irregularities to reduce the contact area between the film and a guide roll or the like during film production. The method is as follows:
There is a method of adding inert particles, but in applications such as magnetic tape for video, etc., if the particles are large, there are problems such as dropout of information such as magnetic recording signals. A method that satisfies both parties is required.

Such methods include adding inorganic fillers such as silicon oxide and titanium oxide to polyester, which is the film base material (Japanese Patent Application Laid-Open No. 54-57562), and adding calcium carbonate fine particles, silica, or hydrated alumina silicate. A method (US Pat. No. 3,821.156) and the like have been proposed. However, according to these methods,
There is a problem with the dispersibility of the inorganic filler blended into polyester, and improvements in slipperiness and dropout resistance are also insufficient.

Furthermore, in general, the smaller the particle size of the various powders added to the film, the more easily they aggregate, resulting in the addition of large aggregate particles.

As a method to improve these problems, the average particle size is 0.01 to 4.
1 m of silicone resin fine powder (polymethylsilsesquioxane powder) is added to the base polymer at a ratio of 0.005 to 1
．． A method of blending 0 parts by weight has been proposed (Japanese Unexamined Patent Application Publication No. 1983-1999)
According to this method, the slipperiness of the film is significantly improved compared to the conventional method, but the polymethylsilsesquioxane powder also has a small particle size. Indeed, a certain amount of aggregation occurs, and it ends up existing in the film as aggregates. Therefore, even when polymethylsilsesquioxane powder is used, the current situation is that its characteristics of small particle size and good dispersibility are not fully utilized.

[Object of the Invention] An object of the present invention is to provide a biaxially oriented polyester film having excellent slip properties and abrasion resistance.

[Structure 1 of the Invention] As a result of repeated research to achieve the above object, the present inventors found that by blending polymethylsilsesquioxane powder surface-treated with an organosilicon compound into a polyester resin, the powder agglomerates. We have discovered that it is possible to uniformly disperse and blend the ingredients without having to do so, and have completed the present invention.

The biaxially oriented polyester film of the present invention is characterized by containing 0.001 to 3% by weight of polymethylsilsesquioxane powder surface-treated with an organosilicon compound.

The biaxially oriented polyester film of the present invention is obtained by further biaxially stretching an unstretched polyester film in which polymethylsilsesquioxane powder surface-treated with an organosilicon compound is uniformly dispersed and contained therein. .

The polyester film used in the present invention is a polyester film containing aromatic dicarboxylic acid as the main acid component and aliphatic glycol as the main alcohol component.

The polyester is a substantially linear polymer that can be formed into a film.

Examples of the aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, dipheninoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid. can do.

The fatty acid glycol includes ethylene glycol,
trimethylene glycol, tetramethylene glycol,
Examples include polyethylene glycols having 2 to 10 carbon atoms such as pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, and alicyclic diols such as cyclohexane dimetatool.

In the polyester used in the present invention, 80 mol% or more of the total acid component is a terephthalic acid unit or a 2,6-naphthalene dicarboxylic acid unit, and 80 mol% of the total alcohol component is
0 mol% or more of ethylene glycol units 1 For example, polyethylene terephthalate, polyethylene-2,
6-naphthalate is preferred.

In this case, less than 20 mol% of the total acid component is composed of the aromatic dicarboxylic acid units, fatty acid dicarboxylic acid units such as adipic acid and sebacic acid, or alicyclic dicarboxylic acid units such as cyclohexane 1,4-dicarboxylic acid. can do.

Similarly, less than 20 mol% of the total alcohol component is comprised of aromatic diol units such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, 1.
It can be composed of aliphatic diol units containing aromatics such as 4-dihydroxymethylbenzene, and polyalkylene glycol units (polyoxyalkylene glycol units) such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

In addition, the polyester used in the present invention contains an aromatic oxyacid unit such as hydroxybenzoic acid and an oxycarboxylic acid unit such as an aliphatic oxyacid such as ω-hydroxycaproic acid, based on the total amount of acid components. It can also be contained in an amount of less than mol%.

Furthermore, the polyester used in the present invention may be present in an amount within a substantially linear range, such as 2 mol % based on the total acid component.
It is also possible to contain the following amounts of trifunctional or more functional polycarboxylic acid units or polyhydroxy compound units, such as trimellitic acid units and pentaerythritol units.

The polyester film of the present invention contains polymethylsilsesquioxane powder surface-treated with an organosilicon compound.

This organosilicon compound is - deceased: (RzSi)-Z (wherein R represents an unsubstituted monovalent hydrocarbon group and/or a fluoroalkyl group, a represents 1 or 2, Z represents a group in which a is 1 When , hydrogen atom, halogen atom, hydroxyl group, -〇R.

-NR' X, -0NR''8 Also bar 00 CR'
, and when 8 is 2, it represents 10--N (X)' - or -S-, where Ro is a carbon atom number of 1 to
represents four alkyl groups, and X represents a hydrogen atom or an alkyl group similar to Ro.

The organosilicon compound represented by the above formula acts to reduce the silanol groups on the surface of the polymethylsilsesquioxane powder and further bond triorganosilyl groups, thereby making the polymethylsilsesquioxane powder water repellency can be improved.

The monovalent hydrocarbon group R in the formula representing an organosilicon compound includes a methyl group, an ethyl group, a propyl group, a butyl group,
Alkyl groups such as pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, dichloropentyl group, cycloalkyl group such as cyclohexyl group = 2-phenylethyl group, 2-phenylpropyl group Examples include aralkyl groups such as phenyl groups, aryl groups such as tolyl groups, alkenyl groups such as vinyl groups and allyl groups, but from the viewpoint of ease of synthesis, alkyl groups with carbon fi 1 to 4 are preferred. is preferred.

Such organosilicon compounds include trimethylsilane,
Triethylsilane, trimethylchlorosilane, trimethylsilanol, trimethylmethoxysilane, trimethylethoxysilane, hexamethyldisilazane, (CH
-, ), S i NHCH,.

(CH,)s S i N (CH-1g, (CHs)
n S i N (C* Hsls, (CH3)5 S
i ON (C, H, 1,, (CHsls S iO
CC)l s, CH.

For example, hexamethyldisilazane or a disilazane containing a polyfluoroalkyl group is preferred in view of the water repellency of the product and the ease of its removal.

The polymethylsilsesquioxane powder used in the present invention is disclosed in JP-A-60-13813 or JP-A-63-13813.
It can be produced by the method described in Japanese Patent No. 103812.

The polymethylsilsesquioxane powder obtained in this way has an almost perfect spherical shape with each individual being independent, and in its particle size distribution, 80% or more is within ±
The average particle size is preferably in the range of 30%, and although the average particle diameter is not limited to 0.1 to 20 μm, it is preferable because it is easy to obtain a perfectly spherical powder.

The surface treatment method for the polymethylsilsesquioxane powder may be any method as long as the surface of the polymethylsilsesquioxane powder can be coated with the organosilicon compound represented by the above formula. may be 1
For example, a known surface treatment method for silica powder can be applied. That is, a method of treating polymethylsilsesquioxane powder by mixing and contacting it with the organosilicon compound while keeping it in a fluid state (Japanese Patent Publication No. 1983-
41263) or a method in which polymethylsilsesquioxane powder is mixed with the organosilicon compound at a temperature ranging from room temperature to 300° C. while stirring and brought into contact with each other can be applied.

The amount of the organosilicon compound used in the surface treatment of the polymethylsilsesquioxane powder can be appropriately selected depending on the type, treatment time, treatment temperature, and the like.

After surface-treating in this way, the object to be treated is heat-treated at a temperature of 50°C or higher to remove unnecessary substances.
A surface-treated polymethylsilsesquioxane powder of the present invention can be obtained.

The polymethylsilsesquioxane powder surface-treated with an organosilicon compound has a particle size of 0.01 g.
m or more, preferably in the range of 0.1 to 5 μm. If the particle size is too small, the slipperiness of the film will be poor.
This is preferable because it results in poor running properties when used as a tape. On the other hand, if the particle size is too large, the surface of the tape becomes rough, which is undesirable because it causes dropouts when used as a magnetic tape, for example.

The amount of the organosilicon compound to be treated is preferably 0.05 parts by weight or more based on 100 parts by weight of the polymethylsilsesquioxane powder.

If the amount is less than 0.05 parts by weight, the dispersibility of the polymethylsilsesquioxane powder will decrease, which is not preferable.

The content of polymethylsilsesquioxane powder surface-treated with an organosilicon compound in the biaxially oriented polyester film of the present invention is 0.001 to 3% by weight, preferably 0.05 to 0.5% by weight. This blending amount is o, oo
If it is less than i% by weight, running properties will be reduced when used as a magnetic tape, and if it exceeds 3% by weight, dropouts will increase. The polyester film of the present invention contains titanium dioxide,
Silica, calcium carbonate, calcium phosphate, etc. can be dispersed and blended. These particles need to be smaller than the average particle diameter of the surface-treated polymethylsilsesquioxane powder.

The average surface roughness of the polyester film of the present invention is not particularly limited, but the average surface roughness of at least one side is 0.0.
The range of 0.02 to 0.05 μm is preferable because it provides good runnability and dropout when used as a magnetic tape.

Further, the coefficient of static friction of the polyester film of the present invention is not particularly limited, but the coefficient of static friction on at least one side is 0.
It is preferable that the number is in the range of 2 to 3.0 since this results in good runnability and dropout when used as a magnetic tape.

[Effect of the Invention J The biaxially oriented polyester film of the present invention has excellent slipperiness and abrasion resistance, and also has less occurrence of scratches and white powder.

The biaxially oriented polyester film of the present invention is suitable as a base film for magnetic recording media, particularly for magnetic tapes, but can also be applied to other fields such as electrical applications, packaging applications, and vapor deposited films. .

[Example] The present invention will be described below with reference to an example. In addition, all "parts" in the examples represent "parts by weight", and each characteristic etc. below was tested by the Shimohi method.

Average surface roughness: Measured using a stylus type surface roughness meter according to J15-B-0601. Note that the cutoff is 0
．． 08 mm, and the measurement length was 4 mm.

Static friction coefficient: Measured using a slip tester according to ASTM-D-1894-63. The weight was 200g.

Dropout: CO-containing -Fe a Oa, polyester urethane, vinyl chloride-vinyl acetate copolymer,
After thoroughly kneading a magnetic coating liquid consisting of butyl acetate and methyl isobutyl ketone, triisocyanate is further added and dispersed to form a magnetic coating liquid. This magnetic coating liquid was applied onto the polyester film to a thickness of 5 μm.

dry. Thereafter, it is calendered, and each copy is slit to a width of 2 inches and incorporated into a video cassette. Next, a video deck was used to input and reproduce the signal, and a dropout counter (TG-7/l manufactured by Shibaku) was used to count the number of dropouts that remained at -16 dB for 5 μsec.

Measurement was performed for 60 minutes, and 1/60 of the measurement was taken as the number of dropouts.

Using a videotape obtained in the same manner as in the runability nitrotube out test, playback and rewinding were repeated for 48 continuous hours on a video deck. After 48 hours, if all of the following three conditions were satisfied, the running performance was determined to be good, and if any one of the conditions could not be satisfied, the running performance was determined to be poor.

■The edges of the tape will not bend and become seaweed-like.

■The tape will not tear or break.

■The decrease in output is less than 2 dB.

Production Example 1 1000 parts of hexamethyldisilazane was placed in a four-bottle flask equipped with a thermometer, a reflux device, and a stirrer, and 1000 parts of hexamethyldisilazane was added to
Average particle diameter 2 obtained by the method described in Publication No. 13813
1000 parts of µm polymethylsilsesquioxane powder was added, stirred at 25°C, and kept for 15 hours for surface treatment.Next, the surface treated product was suctioned using filter paper, and then dried at 200°C. It was dried in the machine to obtain surface-treated polymethylsilsesquioxane powder (P-1).

Surface treatment was carried out in the same manner as in Production Example 1, except that polymethylsilsesquioxane powder produced by the method described in Production Example 2, each having an independent, almost perfect spherical particle shape and an average particle diameter of 0.8 μm was used. polymethylsilsesquioxane powder (P
-2) was obtained.

Production Example 3 In Production Example 2, the operation of holding at 25°C for 15 hours was repeated.
The operation was held at 20°C for 6 hours, and the average particle size was 0.
．． A surface-treated polymethylsilsesquioxane powder (P-3) was obtained in the same manner as in Production Example 2 except that 4 μm polymethylsilsesquioxane powder was used.

Example 1 110 parts of P-1 obtained in Production Example 1 and 0.5 part of polyether modified silicone oil TSF4440 (manufactured by Toshiba Silicone ■, product name) were added to 90 parts of ethylene glycol,
I ran it through a ball mill. Thereafter, it was filtered through a 325-mesh wire mesh to obtain an ethylene glycol dispersion.

Next, 100 parts of dimethyl terephthalate, 80 parts of ethylene glycol, and 4 parts of the above ethylene glycol dispersion (p contained when unreacted ethylene glycol was removed)
-t is approximately 0.4% by weight of the produced polyester)
and 0.01 part of zinc acetate to polymerize and obtain the intrinsic viscosity [η
]=Oy65 polyethylene terephthalate pellets were obtained. This pellet was heated at 180°C for 3 hours under reduced pressure (3T).
orr) After drying, the 6th one supplied to the extruder was heated at 300°C.
The mixture was extruded onto a casting drum with a surface temperature of 30° C., wound around the drum, and cooled and solidified (electrostatic casting method) to obtain an unstretched film with a thickness of about 150 μm.

Thereafter, this film was stretched 3.4 times in the longitudinal direction at 90°C. This stretching was performed using the difference in circumferential speed between two sets of rolls, and the stretching speeds were to and oo.

Next, this -axially stretched film was stretched 3.6 times in the width direction at 100° C. at a stretching rate of 2.000%/min using a stenter. After that, it was heated at 210℃ for 5 minutes under constant length.
Heat treatment was performed for seconds to obtain a film with a thickness of 12 μm.

The surface roughness of this film was 0.019 μm, and the coefficient of static friction was 1.4.

Next, when this film was used as a magnetic tape and the number of dropouts was measured, it was found to be 0.2 dropouts/min, which was good. In addition, the running properties were also good.

Example 2.3 Using P-2 and P-3 obtained in Production Example 2.3, ethylene glycol dispersions containing the respective powders were obtained in the same manner as in Example 1.

Next, a pellet of polyethylene terephthalate was obtained in the same manner as in Example 1 except that 3 parts of this ethylene glycol dispersion was used, and a film was further obtained. This film was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1.2 Polymethylsilsesquioxane powder used in Production Example 2.3 which was not treated with hexamethyldisilazane (untreated P-
2. A film was obtained in the same manner as in Example 2.3, except that untreated P-3) was used, and evaluated in the same manner as in Example 1.

The results are shown in the table.

Claims (1)

[Claims] A biaxially oriented polyester film containing 0.001 to 3% by weight of polymethylsilsesquioxane powder surface-treated with an organosilicon compound.