JPS63230740A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the title film excellent in chipping resistance without detriment to lubricity, by using a polyester and specified rutile TiO2 particles as principal components. CONSTITUTION:An unoriented film obtained by extruding a composition obtained by adding rutile TiO2 particles to a polyester at 270-330 deg.C so that formulas I-IV [wherein alpha is the average particle diameter (mum), beta is the content (wt.%), and gamma is the crystallization acceleration coefficient ( deg.C)] may be satisfied is stretched in the machine direction at a stretch ratio of 3-4, a temperature from the glass transition point of the polymer minus 10 deg.C to this point plus 10 deg.C and a stretch speed of 1,000-10,000%/min, and stretched in the crosswise direction at a stretch ratio of 3-4, 80-160 deg.C and a stretch speed of 1,000-20,000%/min, and heat-treated at 150-220 deg.C for 0.5-60sec to obtain a biaxially stretched polyester film of a total reflection Raman crystallization index on the film surface >=13cm<-1>, a surface orientation index of 0.935-0.975, a density index of 0.02-0.05, a surface roughness in the crosswise direction (Ra) of 0.005-0.030mum and a melt viscosity at 290 deg.C and 200sec<-1> of 1,000-10,000P.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to biaxially oriented polyester films.

[Prior Art] As a biaxially oriented polyester film, a film in which anatase type titanium dioxide is contained in polyester is known (for example, JP-A-61-237623).

[Problems to be solved by the invention] However, the above conventional biaxially oriented polyester film has the following problems:
As the processing speed of film increases, such as the printing process for packaging applications, and the magnetic layer coating/calendering process for magnetic media applications, the surface of the film is scraped by contact rolls, etc., resulting in
Recently, the drawback of causing problems in product performance has become a problem.

It is an object of the present invention to solve these problems and provide a film with excellent surface abrasion resistance while maintaining the film's slipperiness necessary for any use.

[Means for Solving the Problems] A biaxially oriented film mainly composed of a composition consisting of polyester and rutile titanium dioxide particles, the average particle diameter α (μm) of the rutile titanium disuride particles, Content β (
Weight %) and crystallization promotion coefficient r (°C) are expressed by the following formula (1)
A biaxially oriented polyester film that satisfies (4) and has a total reflection Raman crystallization index of 13 cm-'' or more on the film surface.

α≦1.5...(1) β≦1.2...(2
)0.003・α ≦β≦0.1・α−2°24−
2.76 (3) T≦15β (4) The polyester in the present invention includes ethylene terephthalate, ethylene α, β-bis(2-chlorophenoxy)ethane-4,4-dicarboxylene-1, ethylene 2,6
- Contains at least one structural unit selected from naphthalate units as a main constituent. However, other components may be copolymerized within a range that does not impede the present invention, preferably within 15 mol%.

In addition, polyester containing ethylene terephthalate as a main component is particularly desirable because its slipperiness and abrasion resistance are even better.

The titanium dioxide particles (hereinafter abbreviated as particles) in the present invention need to be of rutile type.

The commonly used anaatase type is not preferred because it cannot satisfy the high level of abrasion resistance that is the objective of the present invention.

The average particle diameter α (μm) of the particles in the present invention is expressed by the above formula (1)
It is necessary to satisfy the following.

α≦1.5 (1) If α is larger than the above range, the abrasion resistance will be poor, which is not preferable.

In the present invention, the particle content β (% by weight) in the film must satisfy the following formula (2).

β≦1.2 (2) If B is larger than the above range, the abrasion resistance will be poor, which is not preferable.

The average particle diameter α and the content layer β of the particles in the present invention are determined by the following formula (3
) must be satisfied.

0.003・α≦β≦0.1・α−2・24−2
．． 76...<3) If β is smaller than the above range, the sliding properties will be poor, and if it is larger, the abrasion resistance will be poor, which is not preferable.

In the present invention, the content β of particles and the crystallization promotion coefficient γ are expressed by the following formula (4), preferably (5), more preferably (
6) must be satisfied.

γ≦15β ... (4) γ≦10β
−(5>γ≦5β
(6) If γ is larger than the above range, the abrasion resistance will be poor, which is not preferable.

In the present invention, within the scope that does not impede the purpose of the present invention,
Inorganic particles or internally precipitated particles other than rutile-type titanium dioxide particles may be used in combination, or rutile-type titanium dioxide particles with different particle sizes may be used in combination, but in this case, at least rutile-type titanium dioxide particles , it is necessary to satisfy the relational expressions (1) to <4) of the present invention.

The film of the present invention has the above-mentioned composition as a main component, but other polymers may be blended within the range that does not impede the purpose of the present invention, and antioxidants, heat stabilizers, lubricants, ultraviolet absorbers, etc. Inorganic or organic additives such as agents, nucleating agents, etc. may be added to the extent that they are normally added.

The film of the present invention is a film in which the above composition is biaxially oriented. An unstretched film or a -axis oriented film is not preferred because it has poor slip properties and abrasion resistance.

In addition, the plane orientation index representing the degree of biaxial orientation is not particularly limited, but is 0.935 to 0.975, particularly 0.94
A range of 0 to 0.970 is particularly desirable because the slip properties and abrasion resistance become even better.

The film of the present invention has a total reflection Raman crystallization index of at least one side of 13 cm -1 or more, preferably 15 cm -1 or more, and more preferably 17 cm -1 or more.

If the total reflection Raman crystallization index is smaller than the above range, the abrasion resistance will be poor, which is not preferable. Note that the upper limit of the total reflection Raman crystallization index of the surface is not particularly limited, but is 24
The manufacturing limit is around cm-''.

Here, this total reflection Raman crystallization index is the half-value width of the Raman band based on the stretching vibration of the carbonyl group in the total reflection Raman spectrum measured by the method described below.
The half-width of this Raman band is inversely proportional to the density of polyester, that is, the degree of crystallinity.
This is what was reported by elVeger (J
, Polymer 5science, 10,317
．． 1972).

Further, the density index of the film of the present invention is 0.02 to 0.0
A value in the range of 5 is particularly desirable because the slipperiness becomes even better.

The film of the present invention has an average surface roughness Ra of 0.0 in the width direction.
05-0.030μm, especially 0.007-0.025μm
A range of m is particularly desirable because the slipperiness becomes even better.

The film of the present invention has a melt viscosity of 1,000 to 10,000 poise at 290°C and 200 sec, particularly 2,000 poise.
A range of 7,000 to 7,000 voids is particularly desirable because the abrasion resistance is even better.

Next, a method for producing the film of the present invention will be explained.

First, to add rutile titanium dioxide to a given polyester, it can be added before, during, or after polymerization, but it can be added in the form of a slurry to ethylene glycol, which is the diol component of polyester. , the method of dispersing and adding is effective for satisfying the relational expression (4) of the present invention. Further, as a method for adjusting the content of particles, a method of diluting a highly concentrated master pellet during film formation is effective for obtaining the relational expression (4) of the present invention.

In addition, ethylene glycol slurry was added to
A method of heat treatment at a temperature of 180 to 200 °C for 30 minutes to 5 hours, especially 1 to 3 hours, or a method of adding 0.5 to 20% by weight of ammonium phosphate to the particles is disclosed in this book. This is extremely effective in obtaining the relational expression (4) of the invention and the total reflection Raman crystallization index of the film surface.

In addition, by adjusting the melt viscosity and copolymer 1 component of the master pellet at a high concentration, preferably 1 to 5% by weight, the difference between the glass transition point Tq and the cold crystallization temperature Tcc (Tcc - Tg) is adjusted to 65% by weight. It is extremely effective to maintain the temperature at ~110[deg.]C1, particularly 75 to 100[deg.]C, to obtain the Raman crystallization index of the surface of the film within the range of the present invention. In this case, the preferred copolymerization component is an isophthalic acid component.

After sufficiently drying the pellets containing a predetermined amount of inert inorganic particles, the pellets were fed to a known melt extruder and 27
It is extruded into a sheet through a slit-shaped die at 0 to 330°C, and cooled and solidified on a casting roll to produce an unstretched film.

Next, this unstretched film is stretched on two wheels to form a biaxial control surface. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, using a sequential two-wheel stretching method in which stretching is first performed in the longitudinal direction and then in the width direction,
A method in which the stretching is carried out in a narrow range of (glass transition point of the polymer +'IO°C) and at a relatively low stretching speed of 1000 to 10000%/min is desirable in order to bring the Raman crystallization index of the film surface within the range of the present invention. . Stretching temperature in the width direction,
The speed is preferably in the range of 80 to 160°C and 1000 to 20000%/min. The stretching ratio is 3 in both the longitudinal and width directions.
~4 times is suitable.

Next, this stretched film is heat treated. In this case, heat treatment conditions are preferably 150 to 220°C, preferably 170 to 200°C for 0.5 to 60 seconds under constant length, and microwave heat treatment is particularly suitable.

[Function] The present invention uses rutile-type titanium dioxide particles and has the average particle size, content, crystallization promotion coefficient, and total reflection Raman crystallization index of the film surface within specific ranges. It is presumed that the effects of the present invention were obtained as a result of being able to utilize the hardness of the material.

[Method of Measuring Physical Properties and Evaluating Effects] The methods of measuring the characteristic values and evaluating the effects of the present invention are as follows.

(1) Average particle size α (μm) of inorganic fine particles Polyester is removed from the film by plasma ashing treatment or O-chlorophenol dissolution method, dispersed in ethanol, and stretched sedimentation method (Horiba, CA, (using PA 500)
This is the volume average diameter measured in .

(2> Inorganic fine particle content β (wt%) Add 1°OQ of O-chlorophenol to 100g of polyester 12
After heating at 0°C for 3 hours, use an ultracentrifuge 55P manufactured by Hitachi Koki ■.
-72, stretching separation is carried out at 30.00 Q rpm for 40 minutes, and the obtained particles are vacuum dried at 100°C.

When the fine particles are measured using a scanning differential calorimeter, if a dissolution peak corresponding to the polymer is observed, 0-chlorophenol is added to the fine particles, and after heating and cooling, the stretching separation operation is performed again. When the dissolution peak is no longer observed, the fine particles are considered to be precipitated particles. Normally, two stretching and separating operations are sufficient. The ratio of the particles thus separated to the total weight (wt%)
) is β.

(3) Glass transition point Tg, cold crystallization temperature TCC Measured using a DSC (differential scanning calorimeter) type II manufactured by PerkinElmer. The DSC measurement conditions are as follows. That is, sample 10 mcl@DSC device was loaded with cells 1 to 3.
After melting at a temperature of 00°C for 5 minutes, it is quenched into liquid nitrogen. This rapidly cooled sample is heated at a rate of 10° C./min, and the glass transition point Tg is detected.

The temperature was continued to rise gradually, and the peak temperature of crystallization exotherm from the glass state was defined as the cold crystallization temperature TCC.

Here, the difference between TCC and TQ ('7-cc-Tg> is ΔTc
Define g.

(4) Crystallization promotion coefficient γ (unit: °C) ΔTC of the film containing rutile titanium dioxide particles by the above method
The difference between ΔTCg(II) and ΔTOg(I> [ΔTc
g(II>-8TCg(1))] was defined as the crystallization promotion coefficient γ.

(5) Surface total reflection Raman crystallization index Jobin-
The total reflection Raman spectrum was measured using a Ramanor U-1000 Raman system manufactured by Yvon Co., Ltd., and the half-width of 1730 cm −1, which is the stretching image of the carbonyl group, was taken as the total reflection Raman crystallization index of the surface. The measurement conditions are as follows. The measurement depth is 500 to 1 from the surface.
000 people.

■Light source Argon ion laser (5145 people) ■Setting the sample Press the film surface onto a total reflection prism so that the laser polarization direction (SgiA light) and the film longitudinal direction are parallel, and the incident angle of the laser to the prism ( The angle with respect to the film thickness direction was 60°.

■Detector PM: RCA31034/Photon C
mounting system
u C1230) (supply 1600V) ■Measurement conditions 5LIT 1000μm LASER10
04 GATE DIME 1.0sec
SCAN 5PEE[) 12Cm-”/m
inSAMPLING INTEF? VAL 0.
2cm -”REPEAT TIME 6
(5) Planar orientation index Using an Atsube refractometer with sodium D line (wavelength 589 nm) as a light source, measure the refractive index in the thickness direction of the biaxially oriented film (denoted as A) and quench it in water at 10°C after melt pressing. The refractive index (referred to as B) in the thickness direction of the non-oriented (amorphous) film produced was measured, and A/B was taken as the plane orientation index. Using methylene iodide as the mounting solution,
Measurement was performed at 5° C. and 65% RH.

(6) Density index The density of the film measured using a density gradient tube made of rhohebutane/carbon tetrachloride is dl (g/Q()). After melt pressing, this film is rapidly cooled in water at 10°C. The difference from the density d2 of the produced non-oriented (amorphous) film, (dl-d2>), was taken as the density index.

(7) Measurement was performed using a melt viscosity enhancement type flow tester at a temperature of 290°C and a shear rate of 2QQsec-1.

(8) Surface average roughness Ra Measured using a stylus type surface roughness meter according to J15-B-0601. However, the cutoff is 0.08mm
, the measurement length is 1mm LJ:.

(9) Slip property (coefficient of friction with metal guide) Using a tape running property tester model TBT-300 (manufactured by Yokohama System Research Co., Ltd.), run the tape in an atmosphere of 20°C and 60% RH to determine the initial μK (friction coefficient). coefficient) was calculated from the following formula.

μK =0.7330. Qg (T1/T□) where T
Q is the inlet tension, and T1 is the outlet tension.

The guide diameter is 5mmφ, and the guide material is 5LJS27.
(Surface viscosity is 0.23), the angle of winding is 180°, and the running speed is 3.3 cm/sec.

If the above μK is 0.30 or less, the sliding property is good, 0.30
If it exceeds this value, it is determined that the slip property is poor.

A value of 0.30 for μ is the critical point in determining whether troubles due to slippage will occur during processing steps such as a printing process or a calendaring process, or during running when a magnetic tape is used.

<10) Press one blade perpendicularly against a tape-like slit of a 172-inch wide abrasion-resistant film, and run it for 20 cm while pushing it roughly 0.5 mm (J,
Running speed: 6.7 cm/sec). At this time, the height of the scraped material on the film surface attached to the tip of the single blade is read with a microscope, and the amount of scraped material is measured in micrometers.

When the average value of the scratch marks on both sides was 5 μm or less, the scratch resistance was determined to be good, and when it exceeded 5 μm, the scratch resistance was determined to be poor. This value of 5μm is the critical point for strictly determining whether or not problems with the process and product performance will occur due to the film surface being scraped during processing processes such as the printing process and the calendaring process. be.

[Example] The present invention will be explained based on examples.

Examples 1-2, Comparative Examples 1-6 Ethylene glycol slurry containing 2% by weight of rutile titanium dioxide particles having different average particle sizes was prepared. After this slurry was heat-treated at 195° C. for 2 hours, 3% by weight of triethylammonium hydroxide/phosphoric acid 1:1 salt was added as a dispersant to the particles, and the slurry was stirred and dispersed. This ethylene glycol slurry and dimethyl terephthalate were transesterified and then polycondensed to produce particle master pellets of polyethylene terephthalate containing 1% by weight of particles (Example 1). At this time, various master pellets were made with different heat treatment conditions for ethylene glycol, type of dispersant, and polycondensation conditions (
Example 2, Comparative Examples 1 to 6).

The ΔTCg of these master pellets was as shown in Table 1. These particle master pellets and polyethylene terephthalate pellets containing substantially no particles were mixed so that the particle content was a predetermined amount, and the pellets were dried under reduced pressure (3 Torr) at 180° C. for 3 hours.
/Ta. The pellets were supplied to an extruder, melt-extruded at 300°C, wound around a casting drum with a surface temperature of 30°C using an electrostatic casting method, and cooled and solidified to produce an unstretched film with a thickness of approximately 180 μm. . This unstretched film was stretched 3.4 times in the longitudinal direction at 80°C.

This stretching was carried out using a difference in peripheral speed between two sets of rolls, and the stretching speed was 10,000%/min. This -axis film was stretched 3.6 times in the width direction at 100°C at a stretching rate of 2000%/min using a stenter, and then heat-treated at 190°C for 5 seconds under constant length to form a biaxially oriented film with a thickness of 15 μm. Got the film. The average particle size α of the rutile titanium dioxide particles in these films is
μm), content β (wt%), crystallization promotion coefficient γ (°C)
The total reflection Raman crystallization index of the surface was as shown in Table 1. From Table 1, when the relationship between α, β, and γ and the total reflection Raman crystallization index of the surface were within the range of the present invention, a film with good slip properties and abrasion resistance was obtained; It can be seen that it is not possible to obtain a film that has both abrasion resistance and abrasion resistance.

Example 3, Comparative Example 7 An ethylene glycol slurry containing 1% by weight of each of rutile-type titanium dioxide and anatase-type titanium dioxide particles with an average particle size of 0.3 μm was prepared. These slurries were heat-treated at 195°C for 1°5 hours, then dispersed using the same dispersant as in Example 1, transesterified with dimethyl terephthalate, and polycondensed to reduce each particle to 1 weight. Master pellets of polyethylene terephthalate containing %. The ΔTcg of these master pellets was 80°C.

These master pellets and polyethylene terephthalate pellets containing substantially no particles were mixed so that the particle content was 0.5% by weight, and a biaxially oriented film with a thickness of 15 μm was produced in the same manner as in Example 1. . As shown in Table 2, the average particle diameter α, content β, crystallization promotion coefficient γ, and total reflection Raman crystallization index of the surface of these films are within the scope of the present invention. there were. However, as can be seen from Table 2, when the titanium dioxide was rutile type, both slipperiness and abrasion resistance were good, but when titanium dioxide was anatase type, the abrasion resistance was poor.

[Effects of the Invention] The present invention uses rutile-type titanium dioxide particles and sets the average particle size, content, crystallization promotion coefficient, and total reflection Raman crystallization index of the film surface within specific ranges, so that the slip property is improved. This results in a film with excellent abrasion resistance that can withstand today's harsh conditions of use while maintaining the same properties.

Although the use of the film of the present invention is not particularly limited, it is particularly useful as a base film for magnetic recording media, where product performance is particularly affected by abrasion of the film surface during processing steps.

Claims (1)

[Scope of Claims] A biaxially oriented film containing a composition consisting of polyester and rutile titanium dioxide particles as main components, comprising an average particle diameter α (μm) of the rutile titanium dioxide, a content β (
weight%) and crystallization promotion coefficient γ (℃) are expressed by the following formula (1) ~
A biaxially oriented polyester film that satisfies (4) and has a total reflection Raman crystallization index of the film surface of 13 cm^-^1 or more. α≦1.5...(1) β≦1.2...(2) 0.003・α^-^2^. ＾7＾6≦β≦0.1・α
^-^2^. ^2^4...(3) γ≦15β...(4)