JPH04132743A - Orientated polyester film - Google Patents

Abstract

PURPOSE:To obtain the subject orientated polyester film excellent in slip properties, traveling properties and abrasion resistance by blending a polyester having a specified elastic modulus with a thermoplastic resin containing inert particles added in polymerization process in a prescribed ratio. CONSTITUTION:An objective film containing (A) a polyester containing no inert particles such as a carbonate of Ca, Mg or Ba, e.g. a copolyester in which >=80mol% of its repeating units is ethylene terephthalate and (B) a thermoplastic resin such as a polyester-based resin containing inert particles added in polymerization process and having a dynamic elastic modulus lower than that of the above-mentioned component (A) in 0.1-10wt.% ratio of the component (B) to the component (A) and capable of producing a magnetic tape having an excellent magnetic characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an oriented polyester film, and particularly to an oriented polyester film having excellent abrasion resistance.

(Prior art) Polyesters, represented by polyethylene terephthalate, generally have excellent physical and chemical properties, so
Used in various fibers and molded products. Furthermore, films made of polyester can be used, for example, in magnetic tapes, photographs,
It is used in a wide range of applications, including capacitors and packaging films. When using films for various purposes, the slipperiness of polyester determines the workability of the film manufacturing process and processing steps for each application, as well as the quality of the products in which the film is used. This is a major factor.

As a method for improving the slipperiness of a film, a method is known in which the contact area between the film and a guide roll or the like is reduced by providing unevenness to the film surface. For example, when synthesizing the polymer used in the film, there is a method in which catalyst residue is precipitated to impart irregularities to the film, and a method in which inert inorganic particles are added to the resin.

However, in recent years, as the processing speed has been rapidly increased, a phenomenon has appeared in which the protrusions added to the film surface to improve slipperiness peel off and precipitate as white powder. In particular, when a magnetic material is applied to the surface of a polyester film and used as a magnetic tape, the friction between the calender roll used to apply the magnetic material and the film surface causes protrusions on the film surface to peel off, resulting in white powder. and adheres to the film surface. When such a phenomenon occurs, dropouts of magnetic recording signals, that is, dropouts are likely to occur.

The adhesion of the white powder is particularly noticeable when a method of adding inert inorganic particles to polyester is used. The reason for this is that the affinity between the organic component polyester and the inert inorganic particles is not sufficient, so during the process of stretching and molding the film, separation occurs at the interface between the particles and the polyester, creating voids around the particles. This is thought to be because particles on the film surface are likely to peel off.

The following methods have been proposed to avoid such shedding of inert particles: (1) Grafting glycol onto the surface of inorganic particles to improve the affinity between the inorganic particles and polyester ( Japanese Patent Publication No. 60-280763
and (2) a method of improving abrasion resistance by controlling the crystallization coefficient of polyester on the film surface (Japanese Patent Laid-Open No. 62-201938). However, such a method does not provide a film with sufficient abrasion resistance.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to reduce the surface The purpose of the present invention is to provide an oriented polyester film with excellent abrasion resistance so that the protrusions do not fall off.

(Means for Solving the Problems) The oriented polyester film of the present invention is an oriented polyester film containing a polyester containing substantially no inert particles and a thermoplastic resin to which inert particles are added during polymerization. The dynamic elastic modulus of the thermoplastic resin is
is less than the dynamic elastic modulus of the polyester, and contains the thermoplastic resin in an amount of 0.1% to 1% by weight based on the polyester.
It is contained in a proportion of 0% by weight, thereby achieving the above object.

The polyester used in the present invention is a crystalline polyester such as polyalkylene terephthalate and polyalkylene naphthalate. Particularly preferred is polyethylene terephthalate or a copolymerized polyester in which 80 mol% or more of the repeating units are ethylene terephthalate. Other polymeric components contained in the copolymerized polyester include the following dicarboxylic acid components and glycol components. As dicarboxylic acid components, isophthalic acid, p
-β-oxyethoxybenzoic acid, 2.6-naphthalene dicarboxylic acid, 4.4'-dicarboxydiphenyl, 4,
4°-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, 5-
Sodium sulfoisophthalic acid, cyclohegyusan-1.
4-dicarboxylic acids and the like. Glycol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexane dimetatool, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. p
-Oxycarboxylic acids such as oxybenzoic acid may also optionally be used. Furthermore, a small amount of a compound having an amide bond, urethane bond, ether bond, or carbonate bond may be contained as another copolymerization component.

Such a polyester may be produced by any production method such as a direct polymerization method in which the dicarboxylic acid component and the glycol component are directly reacted, or a transesterification method in which the dimethyl ester of the dicarboxylic acid component and the glycol component are transesterified. is available.

Inert particles used in the present invention include Ca, Mg,
Carbonates of Sr, and Ba; Na, K,
Sulfates of Mg, Ca, Ba and AI; Na,
K, Mg, Ca, Sr, Ba, AI, Ti and Zr phosphates; silicon dioxide; aluminum oxide: complex silicate compounds (amorphous or crystalline clay minerals, aluminosilicate compounds, etc.); warm asbestos ( zircon, crya2, etc.); oxides of Zr and Ti;
Terephthalates of Ca, Ba, Zn and Mn; L
benzoate of i; chromate of Ba and Pb; carbon (
glass (glass powder, glass beads, etc.); fluorite; and inorganic particles such as ZnS. Furthermore, cross-linked polystyrene resin,
Organic particles such as cross-linked acrylic resins, benzoguanamine resins, silicone resins, and cross-linked polyester resins may also be used. In particular, calcium carbonate, anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate, barium sulfate, calcium phosphate, zirconium phosphate, titanium oxide, lithium benzoate, glass powder, clay (kaolin, bentonite, clay, etc.), talc. and diatomaceous earth are preferred. These inert particles may be natural or synthetic. These inert particles may be used alone or in combination of two or more.

Although the shape of the above-mentioned inert particles is not particularly limited, particles that are nearly perfectly spherical can provide a film with good slipperiness and abrasion resistance. Therefore, particles whose area ratio with respect to the circumscribed circle defined by the following general formula is 60% or more are preferably used.

In the above formula, the cross-sectional area of the particle is determined from a projected view of the particle obtained using a scanning electron microscope.

The area of the circumscribed circle is the area of the circle circumscribed to the projection of the particle.

Furthermore, the average particle diameter of the inert particles is 0.05~5゜0.
It is preferable that the particle size is 0.1 to 2.5 μ, especially 0.1 to 2.5 μ.

If the average particle diameter is less than 0.05 μm, the slipperiness and abrasion resistance of the resulting film cannot be sufficiently improved. If it exceeds 5.0 μm, it is not preferable because it increases the possibility that coarse protrusions will be formed on the film surface when the film is formed. In order to obtain a predetermined average particle size, commercially available
Alternatively, it is preferable to classify or filter synthesized inert particles before use.

The thermoplastic resin used in the present invention is a thermoplastic resin having a dynamic elastic modulus (E) lower than the dynamic elastic modulus (E) of polyester, which is the main component of the film. The type of thermoplastic resin is not particularly limited, and any resin can be used. Examples include resins such as polyester, polyether, polyamide, polycarbonate, polyurethane, polyester amide, polyester urethane, polyether urethane, and vinyl polymer polysiloxane. In particular, polyester, polyamide, polyurethane, polyester amide, polyester urethane, and the like, which have good compatibility with polyester, are preferred, and polyester resins are more preferred. In order to improve adhesion with inert particles, functional groups such as hydroxyl groups, carboxyl groups, sulfonic groups, phosphoric acid groups, ami7 groups, silyl groups, phosphonic acid groups, and oxazoline groups may be introduced into the resin. good.

The inert particles are added to the thermoplastic resin during polymerization. The timing of adding the inert particles is not particularly limited, and they can be added at any stage of the polymerization reaction of the thermoplastic resin as long as they do not inhibit the polymerization reaction. The inert particles may be added to the polymerization reaction vessel in powder form or as a slurry dispersed in a suitable solvent. When polyester is used as the thermoplastic resin, it is preferably added in the form of a slurry in order to prevent particle splashing, control the particle supply rate, and uniformly disperse the particles. In particular, it is preferable to add it as a slurry of ethylene glycol. The slurry is preferably a slurry in which the original primary particles are uniformly dispersed without particles coagulating with each other. In order to improve the binding between the thermoplastic resin and the inert particles, the surface of the inert particles may be subjected to physical or chemical treatment, or a small amount of other compounds may be added together with the inert particles. . As other compounds, conventionally known silane coupling agents, titanate coupling agents, and the like may be used.

The amount of inert particles added to the thermoplastic resin is 0.01 to 2, particularly preferably 0.01 to 2, in weight ratio to the thermoplastic resin.
．． 1-1.

The distributed polyester film of the present invention is prepared as follows using the above polyester and a thermoplastic resin containing inert particles. First, the thermoplastic resin containing the polyester and inert particles is thermally melted,
Mix using a two-wheel extruder, Brabender roll kneader, etc. The mixing method is not limited to these.

The amount of the thermoplastic resin containing the inert particles added is 0.1 to 10.0% by weight, preferably 0.5 to 4.0% by weight, based on the polyester. Addition amount is 0.1
If it is less than % by weight, the amount of inert particles is too small, resulting in a low protrusion density on the film surface, resulting in insufficient slipperiness and abrasion resistance. When the amount of thermoplastic resin exceeds 10.0% by weight, the original physical properties of the polyester are impaired.

Inert particles other than the inert particles added to the thermoplastic resin may be added to the above mixture to the extent that the effects of the present invention are not impaired. Inert particles include inorganic particles such as silica, titanium oxide, kaolinite, and calcium carbonate;
Additionally, organic particles such as crosslinked polystyrene polymer beads, polyacrylic acid polymer beads, etc. can be used. Furthermore, if necessary, we also add anti-agglomerating agents to suppress the agglomeration of inert particles, additives to improve the electrostatic adhesion of the film, stabilizers to prevent side reactions such as coloring, colorants, and electrostatic Various additives such as inhibitors and ultraviolet absorbers may be added.

Next, the molten mixture is formed into a film by any method and stretched in the l-axis or bi-axis direction to produce an oriented polyester film. When producing a biaxially oriented polyester film, it may be stretched in both directions at the same time, or it may be stretched sequentially.

When sequential stretching is performed, the stretching may be performed first in the longitudinal direction and then in the transverse direction, or vice versa.

Furthermore, the stretching may be performed in multiple stages of two or more stages.

The temperature during stretching is not particularly limited, but a temperature higher than the Tg of the main component polyester is recommended.

As the stretching method, any known method such as the stenter method or the tubular method can be used.

In this way, the oriented polyester film of the present invention is produced by first dispersing inert particles in a thermoplastic resin having a dynamic elastic modulus smaller than that of the main component polyester, and then dispersing the thermoplastic resin into the polyester. Because of this, the inert particles on the film surface are covered with a thermoplastic resin with a low elastic modulus. As a result, the shear elastic stress applied to the protruding portions of the inert particles during processing of the film is relaxed, and wear phenomena such as the inert particles falling off from the film are significantly reduced. Therefore, the oriented polyester film of the present invention has good sliding properties because minute protrusions are formed on the film surface by the inert particles.
Furthermore, it has excellent wear resistance.

(Example) Examples of the present invention will be described below. In the following Examples and Comparative Examples, all parts are by weight unless otherwise specified.

The dynamic elastic modulus (E) of the resin, the particle diameter and area ratio of the inert particles to the circumscribed circle, and the running properties and abrasion resistance of the obtained film were measured as follows.

(1) Dynamic elastic modulus An oriented film stretched 3.5 times in the machine direction and 3.5 times in the transverse direction under temperature conditions suitable for each resin is used as a sample. Using FT Rheospectra DVE-V4 (manufactured by Rheology), the dynamic elastic modulus is measured in the temperature range of 70-150°C while increasing the temperature at a rate of 2°C/min at a frequency of 110Hz.

(2) Particle size of inert particles The particles are sufficiently dispersed in a slurry using ethylene glycol as a solvent. The particle size distribution in the obtained slurry was measured using a light transmission type centrifugal sedimentation type particle size distribution analyzer (manufactured by Shimadzu Corporation 5).
A-CP3).

The particle diameter value at which the cumulative value of the number of particles is 50% is defined as the average particle diameter.

(3) Area ratio for the circumscribed circle An electron micrograph of the particles is taken using a scanning electron microscope (Model S-510, manufactured by Hitachi, Ltd.), and this is enlarged and copied. Further, this is traced and images of 20 particles are randomly filled in with black. The cross-sectional area of each particle in this traced image is measured using an image analysis device Luzex Model 500 manufactured by Reco Co., Ltd. Furthermore, the area of a circle circumscribing these particles is calculated, the area ratio is obtained based on the following formula, and the average value thereof is taken as the area ratio with respect to the circumscribed circle.

(4) Running properties of the film The running properties of the film were evaluated using the apparatus shown in FIG. A film 1 slit to a width of 12.5 mm is
As shown in Fig. 1, four guide rollers 2 with rotating
A film 1 is passed through 1 to 24.2 tension detection devices 31 to 32 and a guide post 4, one end of the film 1 is connected to a crank 5, and a weight 6 weighing 50 g is suspended from the other end. The guide post 4 is a metal guide post for a household VTR, and has a maximum roughness of 0.15 μm and an average roughness of 0.0.
08 μm. The contact angle between the guide post 4 and the film 1 is set to 3π/4 radian. Then, the crank 5 is rotated 100 times at a speed of 8 rpn+, and the coefficient of friction (μ
).

Based on the obtained friction coefficient values, the runnability of the film is ranked into three levels as shown below.

○: μ≦0.25 △:0.25<μ≦0,35 Run for 10m at a speed of

Based on the amount of white powder adhering to the razor, the wear resistance is ranked into three levels as shown below.

○: Hardly any white powder adheres.

△: A large amount of white powder adheres.

×: A very large amount of white powder adheres.

Dog 1 - (a) Production of polyester A continuous esterification reaction device consisting of a two-stage complete mixing tank equipped with an agitator, a flocculator, a raw material inlet, and a product outlet is used for the first esterification of the device. The molar ratio of ethylene glycol to terephthalic acid was adjusted to 1.7, and the amount of antimony atoms was 289pp relative to the weight of terephthalic acid.
An ethylene glycol slurry of terephthalic acid containing antimony trioxide was continuously fed so that the amount of terephthalic acid was 0.3 m.

At the same time, an ethylene glycol solution of magnesium acetate tetrahydrate was supplied from a supply port different from the terephthalic acid ethylene glycol slurry supply port, so that the Mg atoms per polyester unit in the reaction product passing through the reaction vessel was 1100 pp.
The average residence time is 4 at normal pressure.
．． The reaction was carried out for 5 hours at a reaction temperature of 255°C.

The reaction product was continuously taken out of the system and supplied to the second esterification reactor. For the polyester unit in the reaction product passing through the second esterification reactor, 0
．． 5 parts of ethylene glycol and ethylene glycol solution of trimethyl phosphate as P atom 64
The reaction was carried out under normal pressure, with an average residence time of 5.0 hours, and at a reaction temperature of 260°C. The esterification reaction rate of the reaction product in the first esterification reactor was 70%, and the esterification reaction rate of the reaction product in the second esterification reactor was 98%.

The esterification reaction product obtained in this way is continuously supplied to a two-stage continuous condensation reactor equipped with a stirring device, a condenser, a raw material inlet, and a product outlet to perform a polycondensation reaction. The intrinsic viscosity is 0.620. The dynamic elastic modulus at 100°C is 3. A polyester with Ox 10”N/m2 was obtained.

(b) Production of thermoplastic resin containing inert particles 61 parts of terephthalic acid, 39 parts of adipic acid,
19 parts of ethylene glycol and 41 parts of butanediol (composition 1) were charged, and further 0.055 parts of zinc acetate, 0.035 parts of antimony trioxide, and sodium acetate Q
, 040m, heated and heated to a gauge pressure of 3.5k.
g/cm2.The reaction was carried out at 40°C for 90 minutes.

This reactant was added to 30% by weight of calcium carbonate particles with an average particle diameter of 0.8 μm and an area ratio of 72% with respect to the circumscribed circle.
Together with 32 parts of the ethylene glycol slurry, it was transferred to another polymerization mortar, heated and depressurized, and heated to 285°C and 0.5°C. lmmHg
A polycondensation reaction was carried out for 3 hours to obtain a copolymerized polyester containing calcium carbonate particles. The dynamic elastic modulus of this copolyester at 100°C is 5. OX
It was 107N/2 seals.

(e) Production of film 97.5 parts of the polyester obtained in section (a) and 2.5 parts of the copolyester obtained in section (b) were heated at 290°C.
The mixture was melt-mixed using a twin-screw extruder and extruded into a film. 3.5 mm lengthwise at 90'C.
After stretching 3° and 5 times in the transverse direction at 130°C,
A biaxially oriented film of 12 μm was obtained by heat treatment at 0°C.

The properties of the oriented film thus obtained were measured according to the method described above. The results are shown in Example 2 below.
Table 1 shows the evaluation results of the films obtained in -6 and Comparative Examples 1-4.

Yohamagoto (a) Production of polyester A continuous esterification reaction device consisting of a two-stage complete mixing tank equipped with an agitator, a flocculator, a raw material inlet, and a product outlet is used for the first esterification of the device. The molar ratio of ethylene glycol to terephthalic acid was adjusted to 1.7, and the antimony atom was adjusted to 289 ppm to the am of terephthalic acid to the system in which the esterification reaction product was present in the reaction vessel.
An ethylene glycol slurry of terephthalic acid containing antimony trioxide was continuously fed so that the amount of the slurry was +a.

At the same time, an ethylene glycol solution of magnesium acetate tetrahydrate was supplied from a supply port different from the terephthalic acid ethylene glycol slurry supply port, so that the Mg atoms per polyester unit in the reaction product passing through the reaction vessel was 1100 pp.
The average residence time is 4 at normal pressure.
．． The reaction was carried out for 5 hours at a reaction temperature of 255°C.

The reaction product was continuously taken out of the system and supplied to the second esterification reactor. For the polyester unit in the reaction product passing through the second esterification reactor, 0
．． 5 parts of ethylene glycol, 64 ppm as P atoms in ethylene glycol solution of trimethyl phosphate,
Then, the same ethylene glycol slurry of calcium carbonate as that used in Section (b) of Example 1 was continuously supplied from separate supply ports so that the concentration of calcium carbonate was 2500 ppm, and the average residence time was maintained at normal pressure. The reaction was carried out for 5.0 hours at a reaction temperature of 260°C. The esterification reaction rate of the reaction product in the first esterification reactor was 70%, and the esterification reaction rate of the reaction product in the second esterification reactor was 98%.

The esterification reaction product obtained in this way is continuously supplied to a two-stage continuous condensation reactor equipped with a stirring device, a condenser, a raw material inlet, and a product outlet to perform a polycondensation reaction, A polyester containing calcium carbonate particles with an intrinsic viscosity of 0.620 was obtained.

(b) Production of film The polyester obtained in section (a) was melt-extruded into a film using a twin-screw extruder at 290°C. This film was expanded by 3.5 times in the vertical direction at 90℃ and 3 times in the horizontal direction at 130℃.
．． After stretching 5 times, it was heat-treated at 220°C to obtain a biaxially oriented film of 12 μm.

Same as Example 1, except that in (b) of Example 1, spherical silica with an average particle diameter of 0.8μ and an area ratio of 95% with respect to the circumscribed circle was used instead of calcium carbonate particles. A biaxially oriented polyester film was obtained in the same manner.

Example 1 except that barium sulfate particles with an average particle diameter of 0.8 μm and an area ratio of 63% with respect to the circumscribed circle were used instead of calcium carbonate particles in section (b) of Soshiki Main Example 1. A biaxially oriented polyester film was obtained in the same manner.

Example 1 except that hydroxyapatite particles with an average particle diameter of 0.8 μm and an area ratio to the circumscribed circle of 81% were used in place of calcium carbonate particles in (b) of Example 1. A biaxially oriented polyester film was obtained in the same manner as t=.

Moxibustion Supervision I In Section (b) of Example 1, instead of the monomer component of Composition 1, 60 parts of terephthalic acid, 36 parts of adipic acid, 4 parts of 5-sodium sulfoisophthalate ethylene glycol diester, 32 parts of ethylene glycol, and A copolymerized polyester was prepared in the same manner as in Example 1(b) except that 38 parts of neopentyl glycol (composition 2) was used. The dynamic elastic modulus of this copolyester at 100°C is 1. OX 10"N/m2. Using this copolymerized polyester, 2
An axially oriented polyester film was obtained.

In place of the monomer component of Composition 1 in section (b) of L-Plate Takudan Example 1, 49 parts of terephthalic acid, 47 parts of isophthalic acid, 5-
A copolymerized polyester was prepared in the same manner as in Example 1(b) except that 4 parts of sodium sulfoisophthalate ethylene glycol diester, 23 parts of ethylene glycol, and 49 parts of neopentyl glycol (composition 3) were used. The dynamic elastic modulus of this copolyester at 100°C is 2. OX 1o6N/+2.

A biaxially oriented polyester film was obtained in the same manner as in Example 1 using this copolyester.

Same as Comparative Example 1, except that in paragraph (a) of Main Comparative Example 1, spherical silica with an average particle diameter of 0.8 μm and an area ratio of 95% with respect to the circumscribed circle was used instead of calcium carbonate particles. A biaxially oriented polyester film was obtained.

Ruzai 1 Same as Comparative Example 1 except that barium sulfate particles with an average particle diameter of 0.8 μm and an area ratio to the circumscribed circle of 63% were used instead of calcium carbonate particles in section (a) of Comparative Example 1. A biaxially oriented polyester film was obtained.

Comparative Example 1 except that hydroxyapatite particles with an average particle diameter of 0.8 μm and an area ratio of 81% with respect to the circumscribed circle were used instead of calcium carbonate particles in item (a) of Comparative Example 1. A biaxially oriented polyester film was obtained in the same manner as above.

(The following is a blank space) Table 1 As described above, the oriented polyester films of Examples of the present invention have excellent running properties and abrasion resistance.

On the other hand, it can be seen that the film of the comparative example in which the periphery of the inert particles was not covered with a thermoplastic resin having a low elastic modulus had very poor abrasion resistance and poor running properties.

(Effects of the Invention) Since the oriented polyester film of the present invention contains inert particles as described above, minute protrusions are formed on the film surface, and the film has excellent slipperiness and runnability. Furthermore, since the thermoplastic resin with a low elastic modulus is present around the inert particles, the inert particles are difficult to fall off and have excellent wear resistance. Therefore, by using the oriented polyester film of the present invention, the film does not wear out during the film processing process, particularly during the magnetic layer coating process when producing the magnetic tape, and a magnetic tape having excellent magnetic properties can be produced. becomes possible.

4. No. B Figure 1 is an explanatory diagram showing an example of an apparatus for evaluating the runnability of a polyester film.

1... Film, 21-24... Guide roller, 3
1-32... Tension detection device, 4... Guide post,
5...Crank, 6...Weight.

Claims (1)

[Claims] 1. A polyester containing substantially no inert particles;
an oriented polyester film containing a thermoplastic resin to which inert particles are added during polymerization, the dynamic elastic modulus of the thermoplastic resin being less than the dynamic elastic modulus of the polyester; An oriented polyester film containing a resin in a proportion of 0.1% to 10% by weight based on the polyester.