JPS60178024A - Preparation of polyether ester film - Google Patents

Abstract

PURPOSE:To increase tear propagation resistance and reduce irregularity of thickness by a method wherein an unoriented film composed of polyester of a specific structure is stretched in one direction, at a specific temperature and at a specific magnification. CONSTITUTION:Polyether ester having ethylene-alpha,beta-bis(2-chlorophenoxy)ethane 4,4'-dicarboxylate as the principal repetition unit and melting viscosities of 500- 20,000 poise is extruded by a melting extruder in a sheet form, cooled and hardened to form an unoriented film. This unoriented film is stretched by 3.0-5.0 times in one direction and then by 3.0-6.0 times at the cold crystallization temperature of polymer Tcc-Tcc+40 deg.C in the direction rectangular to said direction to obtain polyether ester film. Additionally, it is preferable for higher Young's modulus to stretch this film in one more direction at least.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyetherester film, and more particularly to a method for producing a high Young's modulus film suitable as a base film for magnetic tapes and capacitors.

[Prior art]

Conventionally, polyethylene 1,2-cyphenoxyethane 4,4-cycaldexylate film [also known as polyethylene α, β-bis(
phenoxy)ethane 4,4'-dicaroxylate] is known. As a method for sequentially biaxially stretching this unstretched film, methods disclosed, for example, in Japanese Patent Publication No. 46-11600 and Japanese Patent Application Laid-Open No. 50-97668 are known.

However, the film obtained by this method has a drawback of having a low Young's modulus.

□ [Object of the present invention] The present inventors focused on the polymer itself constituting the film and continued to study it, and as a result, they discovered that polyethylene-α,β-bis(2-chlorophenoxy)ethane 4,4'-dical? It has been found that a film made of xylate has basic properties that are significantly superior to conventionally known polyetherester films.

Conventionally, polyether esters and polyesters have generally been stretched at a temperature in the range above their glass transition point and below their cold crystallization temperature TCC.

As a result of studying the relationship between the stretching conditions and the polymers constituting the film, the inventors found that the general stretching conditions described above were the most suitable varnish and stretching conditions for the specific polyetherester film that they had previously discovered. It has been found that, depending on the conditions, the resulting film has a low tear propagation resistance, that is, a film that is easily torn, and also has a poor Young's modulus, making it unsuitable as a base film for magnetic tapes or capacitors.

The present invention aims to eliminate the above-mentioned drawbacks and provide a method for stably producing a polyetherester film having a high Young's modulus, high tear propagation resistance, and small thickness variation.

〔composition〕

In order to achieve the above object, the present invention has the following structure: an unstretched polyether ester having ethylene-α,β-bis(2-chlorophenoxy)ethane 4,4'-dicarboxylate as a main repeating unit; After stretching the film 3.0 to 5.0 times in one direction, the film is stretched at the cold crystallization temperature of the polymer Tcc to Tcc + 40tl in the direction perpendicular to this.
This is a method for producing a polyetherester film, which is characterized by stretching 3.0 to 6.0 times at a temperature in the range of :'.

The polyetherester used in the present invention is ethylene α, β
-Bis(2-chlorophenoxy)ethane 4゜4'-dicarboxylate is the main repeating unit, but it may contain other copolymer components as long as it does not impede the purpose of the present invention. good. In this case, the copolymer components are:
Dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, α, β-bis(phenoxy)ethane 4,4′-dicarboxylic acid, α(2-chlorophenoxy)-β(phenoxy)ethane 4,4′-dicarboxylic acid Acids or dioxy compounds such as propylene glycol and 1,4-cyclohexane dimetatool are generally used, but from the viewpoint of the Young's modulus of the film, α
(2-chlorophenoxy)-β(phenoxy)ethane 4
, 4'-dicarboxylic acid.

In addition, other types of polymers may be blended with the stream ether ester used in the present invention to the extent that the purpose of the present invention is not impaired. Inorganic or organic additives such as ultraviolet absorbers may be added in the amount normally added.

Further, the melt viscosity of the polyether ester used in the present invention is not particularly limited, but the melt viscosity is 500 to 20,000.
It is particularly preferable that the voids be in the range of 700 to 10,000 poises, since the stretchability, Young's modulus, tear strength, and thickness variation of the resulting film will be better.

The polyether ester pellets described above are extruded into a sheet using a known melt extruder, and are cooled and solidified to produce an unstretched film.

This unstretched film is stretched 3.0 to 5.0 times in one direction, preferably 3.4 to 4.5 times, more preferably 3.8 to 4 times
．． Stretch 2 times. If the stretching ratio is smaller than the above range, the Young's modulus of the obtained film will be poor and the thickness unevenness will be poor, which is not preferable. On the other hand, if the stretching ratio is larger than the above range, the stretching properties will be poor, which is not preferable. Further, the difference in refractive index between the stretching direction and the non-stretching direction and the density of the uniaxially stretched film obtained by this stretching are not particularly limited, but the difference in refractive index (stretching direction - non-stretching direction) is 0.05 to 0. 30, preferably 0.10~
0.25 range, density 1.44-1.47 p/cr
II, preferably in the range of 1.45 to 1.465'/cJ, stretchability, Young's modulus of the obtained film,
This is particularly preferred since tear strength and thickness unevenness are even better. The stretching temperature and stretching speed are not particularly limited, but in order to obtain a uniaxially stretched film with a refractive index and density within the above range, the stretching temperature should be adjusted to the cold crystallization temperature Tcc of the polymer.
-50U -Tcc + 10 U, stretching speed 103
It is suitable to set it to 105%/min.

Next, this −-axis stretched film is stretched in a direction perpendicular to the previous stretching direction at the cold crystallization temperature of the polymer Tcc −Tcc +40C.
1 preferably Tcc+51:'-Tcc+301:'
, more preferably Tcc +5C-Tcc+20
at a temperature in the range of 3.0 to 6.0 times, preferably 3.
It is stretched 5 to 5.5 times, more preferably 4.0 to 5.0 times. If the stretching temperature is lower than the above range, the stretchability will be poor, and the Young's modulus and tear strength of the film will be poor. Conversely, if the stretching temperature is higher than the above range, the stretchability will be poor. This is not preferable because the resulting film has poor Young's modulus, thickness unevenness, and tear strength. Furthermore, if the stretching ratio is smaller than the above range, the obtained film will have poor Young's modulus and thickness unevenness, which is not preferable.

On the other hand, if the stretching ratio is greater than the above range, the stretching properties will be poor, which is not preferable. Further, the stretching speed in this case is not particularly limited, but it is particularly preferable to set the stretching speed to 103 to 105%/min from the viewpoint of stretchability. Further, a method of further stretching a biaxially stretched film in at least one direction is effective in increasing the Young's modulus of the film.

Next, if necessary, the biaxially stretched film can be heat treated. The heat treatment conditions in this case are not particularly limited, but the temperature is 200 to 260C, preferably 200 to 24C.
At 0C, time 0.5-120 seconds, preferably 1.0-120 seconds
The Young's modulus of the obtained film is 60 seconds,
It is particularly suitable for improving tear strength. Further, the heat treatment in this case may be limited shrinkage within 20%, elongation, or constant length state.

The characteristic values of the present invention are based on the following measurement method and evaluation criteria.

(1) Cold crystallization temperature Tcc ・DSC (differential scanning calorimeter) manufactured by KinElmer ■
Measured using a mold. The DSC measurement conditions are as follows. That is, 10 pieces of sample polymer were set in a DSC apparatus and melted for 5 minutes at a temperature of +30C (melting point), and then rapidly cooled in liquid nitrogen. This rapidly cooled sample is heated at a rate of 10 C/min, and the glass transition temperature is detected. The temperature is further increased, and the exothermic peak temperature of crystallization from the glass state is defined as the cold crystallization temperature Tcc.

(2) Refractive index Measured using an Atsube refractometer using sodium D line (wavelength 589 nm) as a light source. Note that methylene iodide or sulfur-methylene iodide solution is used as the mounting solution.
Measured at 25C and 65%RH.

(3) Density Measured at 25C using a density gradient tube made of carbon tetrachloride and n-hebutane.

(4) Melt viscosity 290C using a high slag flow tester.

The measurement was performed at a multi-speed of 200 seconds.

(5) Young's modulus of film according to the method specified in ASTM-D-s82,
Using an Instron type tensile tester, 25C16
Measured at 5% RH. If the Young's modulus of the film in both the longitudinal direction and the width direction is 600 ky/m2 or more, the Young's modulus is good, and the Young's modulus in one or both directions is 60.
If it was less than 0 kl and 7 mm2, the Young's modulus was determined to be poor.

(6) Tear strength of film According to the method specified in JIS-P-8116,
Using an Elmendorf tear tester with Toyo 1nt + A'R tear, the tear resistance (unit: b＾10,000) in the longitudinal and width directions of the film was measured at 25C and 65% RH. The arithmetic mean value is considered the tear track resistance, and if the tear track resistance is 70 P/m or more, the tear strength is:
The tear strength was determined to be good, and if it was less than 70 fP/m, the tear strength was determined to be poor.

(F) Uneven thickness of film Measure the thickness of the film (the nip part is cut) continuously in the width direction (Fil 4J width is IF71).

The difference between the maximum and minimum thickness values is divided by the average thickness, multiplied by 100, and the resulting value is taken as the thickness unevenness. If this value was less than 10%, it was determined that the thickness unevenness was good, and if it was 10% or more, it was determined that the thickness unevenness was poor.

(8) Stretchability If the biaxial stretching film forming operation is performed continuously for 10 hours, and the film breaks 0 to 1 times during that time, the stretchability is good, and if the film breaks 2 or more times, then It was determined that the stretchability was poor.

[Effect]

The present invention employs a special method in which the biaxial stretching ratio is set in a specific range and the biaxial stretching is performed at a temperature in a specific range that is higher than the cold crystallization temperature of the polymer. , the rearrangement occurred smoothly and the following excellent effects could be obtained.

〔effect〕

(1) A manufacturing method that yields a film with a high Young's modulus, high tear resistance, and small thickness unevenness.

(2) A manufacturing method with good stretchability, that is, excellent manufacturing stability.

Next, embodiments of the present invention will be described based on Examples.

Examples 1-4. Comparative Examples 1 to 8 A pellet of polyethylene α,β-bis(2-chlorophenoxy)ethane 4,4'-dicarboxylate (cold crystallization temperature Tcc: 135U) having a melt viscosity of 2500 poise was heated at 180C for 3 hours. After drying under reduced pressure (3 Torr), it was supplied to an extruder, melted and extruded at 300 C into a sheet, wound around a casting drum with a surface temperature of 30 tl' using an electrostatic application method, cooled and solidified, and unstretched to a thickness of about 150 μm. made a film. This unstretched film was stretched in the longitudinal direction and width direction under the stretching conditions shown in Table 1, and then heat-treated at 210C for 15 seconds to produce various films (Experiments &1 to 12). As a result of evaluating the properties (Young's modulus, tear strength, thickness unevenness), the results are shown in Table 1.If the stretching conditions satisfy the conditions of the present invention, the stretchability, Young's modulus of the obtained film, tear strength,
All thickness unevenness was good (Examples 1 to 4). However, if the type of polyester (Comparative Examples 7 to 8) or the stretching conditions (Comparative Examples 1 to 6) are outside the scope of the present invention, the stretchability, Young's modulus, tear strength, and thickness unevenness of the obtained film may be affected. (Table 1, Comparative Examples 1 to 8)
). In particular, it can be seen that when a polyester different from the present invention is stretched in the width direction (biaxially) at a unique temperature higher than the cold crystallization temperature Tcc of the polymer, the stretchability becomes extremely poor.

Example 5. Comparative Examples 9 to 12 Conducted using a pellet of polyethylene α,β-bis(2-chlorophenoxy)ethane 4.4′-cicaldexylate having a melt viscosity of 4500 poise (cold crystallization temperature Tcc: 135 c) The thickness is approximately 150 μm as in Example 1.
An unstretched film was made. This unstretched film
It was stretched 3.9 times in the longitudinal direction at 0C.

This stretching was performed by using a difference in peripheral speed between two sets of rolls, and the stretching speed was 10,000%/min. The uniaxially stretched film thus obtained was stretched at a temperature of 145C using a stenter.
(TCC+1OC), stretched 4.4 times in the width direction at a stretching speed of 1000%/min, and immediately heat-treated at 200C to obtain a biaxially oriented film with a thickness of 9 μm. This stretching operation was performed for 10
There were no tears during the test and the stretchability was good. Further, the thickness unevenness of the obtained film was 2.5 inches, the Young's modulus was 750 in the longitudinal direction, y, /*s+2, and 730 kg/mx2 in the width direction, which were good. In addition, the tear propagation resistance Fi170%/m+ of this film
The tear strength was also good (Table 2, Example 5)
. However, when the type of polyester was outside the scope of the present invention, a film having good stretchability, film thickness unevenness, Young's modulus, and tear strength could not be obtained (Table 2, Comparative Examples 9 to 12). In particular, polyesters other than those of the present invention are processed in the width direction (
It can be seen that a satisfactory film cannot be obtained when stretching is carried out using a biaxial aperture (Comparative Example 10°12).

Procedural amendment June 25, 1980 Manabu Shiga, Commissioner of the Patent Office1, Indication of the case 1982 Patent Application No. 333532, Name of the invention Process for manufacturing polyether ester film 3, Person making the amendment Case Relationship with Patent applicant name (315) Contents of amendment in Column 6 of Detailed explanation of the invention in Toshi Co., Ltd. specification (1) ``Stretching not possible'' in row A6 in Table 1 on page 43 of the specification " is corrected to "stretching in the width direction is not possible."

Claims (1)

[Claims] An unstretched film made of polyether ester whose main repeating unit is ethylene-α,β-bis(2-chlorophenoxy)ethane 4,4'-dicardexylate is stretched in one direction by 3.0 to 5.0 A method for producing a polyetherester film, which comprises stretching 3.0 to 6.0 times in a direction perpendicular to the stretching at a temperature in the range of the cold crystallization temperature of the polymer from Tcc to Tcc + 40C.