JPS63162223A - Treating process of polyester film - Google Patents

Abstract

PURPOSE:To obtain a film excellent in slit property by treating a polyester film in the mixed gas of carbon dioxide with nitrogen, and under pressure. CONSTITUTION:A polyester film is brought in contact with a gas mixed at 1/99-95/5 volume mixing ratio of carbon dioxide with nitrogen under high pressure of 20kg/cm<2>-10kg/cm<2>. As polyester, biaxially oriented and heat-trcated polyethylene terephthalate having especially 40% or more of crystallinity index and 0.03 or more degree of surface orientation, is preferable. As the mixed gas for treatment, the containing of nitrogen gas is essential condition, and if the content of nitrogen gas is not equal to 5% or more, preferably equal to 20% or more, the improvement of slit suitability is not expected. As the treatment temperature at this time, the temperature range from the temperature higher by 40 deg.C them the glass transition temperature (Tg) of polyester and at a cooling and crystallization temperature at the highest to the temperature lower by 40 deg.C than the Tg.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for processing a polyester film, and more specifically, to a method for processing a polyester film that has excellent slitting suitability.

[Prior Art] The slitting suitability of a polyester film, that is, the ease with which the polyester film can be cut in the slitting process in which the polyester film is cut into small pieces of a certain width, especially 10 mm or less, is determined, that is, whether the cut surface is uneven or uneven. It is said that it has excellent slitting suitability when it does not cause various troubles such as saw-toothed edges, hairs or slit pieces attached to the cut surface, or in severe cases, the film cuts during slitting. Previous polyester films had poor slit suitability, resulting in the various types of travel described above. For this reason, conventional methods have been used to change the type of slitting blade, the cutting method, and the roughness by heating or cooling the polyester film.

[Problems to be solved by the invention] However, with the conventional improvements mainly in the cutting method, even if the slit suitability has been improved to some extent, it has not solved the practical problem, especially in the base for magnetic recording. For applications such as film, where adhesion of foreign matter and dust and hairs on the film edges are not preferred, polyester films, which have poor slit suitability, have a fatal drawback.

The object of the present invention is to improve such problems and provide a polyester film with excellent slit suitability.

[Means for Solving the Problems] The present invention provides a polyester film with a volumetric mixing ratio of carbon dioxide and nitrogen of 1/2 to 100 to 9/r:Xl or less under high pressure. The present invention is characterized by a method for treating a polyester film, which is characterized by bringing the polyester film into contact with a mixed gas having a molecular weight of 99 to 9515.

The polyester in the present invention is a polymeric chemical having an ester bond in the main chain of the molecule obtained by condensation polymerization of a dicarboxylic acid and a diol. Typical polyesters include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. , polyethylene α,β-bis(2-chlorophenoxy)ethane4.
These include 4'-dicarboxylate, those copolymerized with other comonomers, and those having an i-thyl bond in the main chain. In the case of the present invention, the effects of the present invention are often more pronounced when the polymer is a homopolymer. Roughly, the polyester of the present invention is biaxially stretched and heat treated, and has a crystallinity of 40% or more and a plane orientation of 0.03.
Although the above-mentioned materials are particularly preferred, materials that have been uniaxially stretched and heat-treated can also be applied if necessary. Of course, polyester contains known additives as polymers,
For example, stabilizers, viscosity modifiers, antioxidants, fillers, slip agents, antistatic agents, antiblocking agents, and the like may be included. It goes without saying that the surface of the polyester film may be laminated with another polymer or subjected to surface treatment such as corona discharge in order to impart a new function. Although the film thickness is not particularly limited, the effect of the present invention is significant when the film thickness is 500 μm or less, preferably 100 μm or less. The polyester film to be processed may be in the form of a single film or a layered film, and in the case of the present invention, polyester film wound into a roll is particularly suitable for economic efficiency, ease of use, and practicality. This is the preferred shape.

Next, the mixed gas to be treated must have a volumetric mixing ratio of carbon dioxide (C02) and nitrogen (N2) in the range of 1/99 to 9515, preferably 5/95 to 80/20. This is because when the CO2 gas content is less than 1%, preferably less than 5%, the improvement in slit suitability, which is an effect of the present invention, cannot be achieved.

On the other hand, when CO2 gas exceeds 95%, preferably 8
Even when it exceeds 0%, the slit suitability cannot be improved to the same extent as above. As described above, it is possible to improve the slitting suitability of a polyester film only when CO2 and N2 are mixed at a certain mixing ratio. In other words, in the case of the present invention, the inclusion of nitrogen gas is an essential requirement, and if the nitrogen gas is not contained at 5% or more, preferably 20% or more, the biaxially oriented polyester film, which has a crystallinity of 40% or more, cannot be used. Therefore, no improvement in slit suitability can be expected.

Of course, a small amount of gas other than CO2 and N2 may be mixed, such as oxygen, water vapor, argon, nitrogen oxide (N
o1NO2, N20, N2O3, N2O5, N03),
Carbon oxide (CoSC302, C502), helium, etc., and gases other than CO2 and N2 should account for less than 50%, preferably less than 30%, of the total volume. Furthermore, when water vapor is contained as low as 10 to 45 RH%, the effect of the present invention becomes remarkable.

Next, the mixed gas is increased to 20 to exceed 9/cnf and 1001q/
The pressure must be d or less, preferably 25 to 50 kcJ/cy+f. Pressure is below 20+1/cnf,
This is because if it is low, preferably less than 25 to 9/-, even if the volume ratio of the mixed gas is within the above range, the slitting suitability of the polyester film, which is the object of the present invention, cannot be improved. Conversely, the pressure is 100 to 9/cn
This is because when it exceeds f, preferably when it exceeds 50 kci/-, not only the effect of the present invention is not recognized as described above, but also the polyester film is deformed and distorted. That is, the present invention exhibits excellent effects such as improved slitting performance only when a specific gas composition and a specific four force range are satisfied.

In addition, the treatment temperature at this time is 40°C higher than the glass transition temperature (g) of the polyester, and the cold crystallization temperature (T).
A range of temperatures from below CC to temperatures 40'C below Tg is effective, but is not necessarily limited thereto. However, the overall effect of treatment below Tg is more significant.

The time required for the next treatment varies depending on the treatment temperature and purpose, but if the purpose is to improve slitting properties, treatment for 4 hours or more, preferably about 20 to 75 hours is recommended.

[Method for measuring physical properties] (1) Glass transition temperature (T (J)) is determined by setting 5 mg of the sample in a scanning calorimeter (DSC) and heating it under a nitrogen stream at a heating rate of 20°C/min. , the arithmetic mean value of the temperature at which the baseline begins to become eccentric and the temperature at which it returns to its original value is used.Alternatively, depending on the sample, if the shape resembles an endothermic peak, the peak thereof is used.

(2) For the cold crystallization temperature (TCC>), draw a thermograph in the same manner as when determining Tg above, and use the peak temperature of exotherm based on crystallization that appears next to TIJ.

(3> Evaluation of slitting properties One side of a PET film with a thickness of 14.5 μm is coated with a magnetic coating liquid having the following composition so that the film thickness after drying is 3 μm.

(Parts by weight) Polyester polyurethane resin 35 PVC/maleic acid copolymer 30 α-alumina
15 carbon black
3 Oleic acid 5 Amyl stearate 4 Triisocyanate compound 22 Ferromagnetic metal powder
300 Butyl acetate 300 Methyl isobutyl ketone 300 After coating, it is oriented in a DC magnetic field, dried, and then calendered. This sheet is slit into 1/2 inch width using a shear cutter to make a videotape. The slit location made by this shear cutter is visually observed, and the degree of generation of whiskers and powder is evaluated by dividing it into the following five grades.

Slitting property A: There is very little generation of whiskers and powder.

tr 3: v Few.

C: Normal level.

+7 D: There are many V -ya.

E: A lot.

(Note) Most of the biaxially oriented PET films for video tapes currently on the market have a slitting level of C or D.

(4) Planar orientation coefficient films were laminated to a thickness of approximately 50 μm to prepare a sample for X-ray diffraction, and an X-ray diffraction apparatus (Ge ige manufactured by Rigaku Denki Co., Ltd.
rf l ex) sample holder.

The diffraction intensity is measured using a reflection method by changing the irradiation angle of X-rays in a plane perpendicular to the longitudinal direction of the film. The measurement conditions are as follows.

Time constant = 2 seconds Traveling speed: 1 degree/min o; vergency s+; t: 1.5
mmΦScattetringSIit: 1
Degree Receiving 5lit: Q
, 3mm X-ray: α rays (3mm
5KV115mA, Ni-filter) 26.0, which corresponds to the diffraction angle of the [100] and [ITO] planes of the PET crystal.
When the diffraction intensities at ' and 22.5 degrees are respectively I1 and I2, the plane orientation coefficient is given by their ratio (II/I2).

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

Examples 1 to 9 Comparative Examples 1 to 5 Polyethylene terephthalate (intrinsic viscosity in O-chlorophenol 0.61, average diameter 150 μm as an additive)
(containing 0.15% titanium oxide and 0.06% synthetic calcium carbonate with an average particle size of 800 mμ) by a conventional method.
It was melted at 5°C, discharged from a T dauro gold, and molded in a casting drum maintained at 25°C without applying an electrostatic charge. Next, the cast film was stretched 3.7 times on a longitudinal stretching roll heated to 95°C, then horizontally stretched 4.2 times at 90°C in a tenter, and then 3x stretched at 190°C.
After heat treatment while relaxing 5% in the width direction for seconds, it was roughly heat treated at 130° C. for 5 seconds at a fixed length. The thus obtained film having a thickness of 75 μm was wound up into a -H roll as an intermediate spool, and then both ends were slit to obtain a product roll.

The biaxially oriented polyethylene terephthalate thus obtained was wound up into a roll with CO2/N2 as shown in Table 1.
24 hours at an ambient temperature of 45°C under pressure under mixed gas.
I processed the time.

Table 1 [Effects of the Invention] In the present invention, a polyester film is treated in a mixed gas of carbon dioxide and nitrogen under pressure, and therefore, the following excellent effects are achieved.

(1) A film with excellent slitting properties can be obtained.

(2) The resulting film has excellent roughness, easy adhesion, and easy sliding properties.

(3) It is also effective in preventing bleed-out of low molecules such as oligomers.

(4) Furthermore, the film has excellent barrier properties against gases such as oxygen and water vapor.

The thus obtained polyester film of the present invention has excellent slit suitability and easy adhesion, so it can be used as a base film for recording such as magnetic recording and optical recording, and exhibits excellent performance. . Of course, it is clear that the polyester film obtained by the present invention can also be used for applications that do not necessarily require proper slitting.

Claims (1)

[Claims] polyester film over 20kg/cm^2,
A method for treating a polyester film, which comprises bringing it into contact with a mixed gas of carbon dioxide and nitrogen having a volumetric mixing ratio of 1/99 to 95/5 under high pressure of 100 kg/cm^2 or less.