KR0163065B1 - Biaxially oriented polyethylene naphthalate film & process of preparation thereof - Google Patents

Abstract

The present invention relates to a biaxially oriented polyethylene naphthalate film and a method for producing the same. 0.01 to 4% by weight of hard calcium carbonate having an average particle diameter of 0.01 to 3 μm, and an average particle diameter of 0.005 to 3 μm and a Mohs hardness of 6 to 0.01 to 4 in polyethylene naphthalate based on the weight of polyethylene naphthalate. Polyethylene naphthalate film prepared by the weight%, 0.05 to 5% by weight based on the weight of the alumina lubricant silane coupling agent has a variety of physical properties. That is, it is excellent in the characteristics of various films including mechanical properties such as surface smoothness and abrasion resistance and scratch resistance, so that the film of the present invention can be widely used in various fields such as capacitor, packaging, photographic film, magnetic recording, industrial, etc. Can be.

Description

Biaxially Oriented Polyethylenenaphthalate Film and Manufacturing Method Thereof

The present invention relates to a biaxially oriented polyethylene naphthalate film and a method for manufacturing the same. Specifically, the biaxially oriented film has improved bi-directional orientation and scratch resistance by improving the dispersibility of a lubricant added in the polyethylene naphthalate film. It relates to a polyethylene naphthalate film and a production method thereof.

Polyethylene-2,6-naphthalate in polyethylene naphthalate (hereinafter abbreviated as PEN) is used for mechanical properties such as tensile strength, elastic modulus, impact strength, heat resistance, durability, chemical resistance, radiation resistance, electrical insulation, etc. Because of good physical and chemical properties, biaxially stretched films are widely used in various fields such as capacitors, packaging, photographic films, magnetic recording media, and industrial applications.

In particular, biaxially oriented films of PEN can increase mechanical strength by high magnification, and have high thermal stability and dimensional stability due to their low heat shrinkage ratio. Polyethylene terephthalate (hereinafter referred to as PET) is widely used as a base film for magnetic recording media. It is evaluated to have excellent physical properties.

According to the excellent characteristics as described above, PEN is used as a base film such as 8 mm, C type of VHS type, VHS type long time recording tape.

In addition, the glass transition temperature is 115 ℃ high heat resistance compared to PET is possible sterilization and disinfection, gas barrier properties are expected to be used a lot of bottles and various packaging containers, and many researches on this.

In order to impart runability, processability, and surface properties to such a PEN film, a method of forming irregularities on the surface of the PEN by introducing inorganic materials such as calcium carbonate, silica, and kaolin as lubricants is used.

However, among these inorganic lubricants, calcium carbonate, especially hard calcium carbonate, has an excellent control effect on the surface characteristics of PEN films, but its hardness is low, resulting in particles falling off due to abrasion during running of the film, and scratches on the surface of the film. Therefore, there is a problem such as causing a dropout (Dropo-out) when made of a magnetic tape.

Conventional PEN film production technology to improve the scratch resistance of PEN film is to use alumina (α, γ, δ-type) mixed with hard calcium carbonate of low hardness to impart the surface and wear resistance of the film and to scratch A method for improving particle dropout by the like has been proposed (Japanese Patent Laid-Open No. 2-214734).

However, the alumina lubricant has a problem that it is difficult to manufacture a high concentration of the slurry due to the central phenomenon during the production of a high concentration of the slurry, the viscosity is high, the stability of the slurry is lowered.

In order to solve the above problems, it is possible to prepare a high concentration of slurry and excellent slurry stability, excellent effect of controlling surface properties of PEN film, and low thermal shrinkage while maintaining high mechanical strength by high magnification stretching. To provide a PEN film having high thermal stability and dimensional stability.

In order to achieve the above object, in the present invention, GaN having 0.01 to 4% by weight of hard calcium carbonate having an average particle diameter of 0.01 to 3 µm, an average particle diameter of 0.005 to 3 µm, and a Mohs hardness of 6 or more in PEN It provides a biaxially orientated polyethylene naphthalate film comprising 0.01 to 4% by weight of delta alumina, 0.05 to 5% by weight based on the weight of the alumina, at least one silane coupling agent selected from the group represented by the following formula. .

Provided that RI in the silane compound is an alkyl group.

Another object of the present invention is to prepare a slurry of high concentration, excellent stability of the slurry, excellent effect of controlling the surface properties of the PEN film, and high thermal strength and low thermal contraction rate while maintaining high mechanical strength by stretching the high magnification and thermal stability It is an object of the present invention to provide a method for producing a high biaxially oriented polyethylene naphthalate film.

In order to achieve the above object, in the present invention, a gamma or delta alumina having an average particle diameter of 0.005 to 3 μm and a Mohs hardness of 6 or more is dispersed in an ethylene glycol slurry, based on the weight of the alumina on the ethylene glycol slurry. Surface treatment of the alumina by the addition of at least one silane coupling agent selected from the group represented by the following formula of 5% by weight, the surface-treated ethylene glycol slurry and ester of hard calcium carbonate having an average particle diameter of 0.01 to 3㎛ Condensation polymerization of the PEN monomer obtained by the exchange reaction, and biaxially stretched by melt extruding the PEN polymer obtained by the polycondensation reaction is achieved by a method for producing a biaxially oriented polyethylene naphthalate.

Provided that RI in the silane compound is an alkyl group.

In order to obtain the PEN of the present invention, first, dimethyl-2,6-naphthalate and ethylene glycol are used in a molar ratio of 1 to 2, and metal components such as manganese, potassium, lithium, calcium, magnesium, zinc, aluminum, and cadmium are included. 0.1 to 0.5% by weight of the catalyst is added to a transesterification reaction.

Other substances that are the same functional derivatives as dimethyl-2,6-naphthalate include dimethyl-1,2-naphthalate, dimethyl-1,5-naphthalate, dimethyl-1,6-naphthalate, dimethyl-1,7-na Phthalates, dimethyl-1,8-naphthalate, dimethyl-2,3-naphthalate, dimethyl-2,7-naphthalate, dimethylterephthalate and the like can be used.

In addition, diols that can be used in addition to ethylene glycol include polyethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 2,2-diethyl-1,3-propanediol, 2,2-dimethyl-1,3 -Propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pantindiol, 1,6-hexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclodimethanol, and the like.

After the transesterification reaction and before the polycondensation reaction, a polycondensation catalyst and a stabilizer are added and dispersed. As the polycondensation catalyst, metal components such as titanium, germanium, tin, antimony, zinc, cobalt, aluminum, lead, manganese and calcium It may or may not be added to the catalyst containing 0.004% by weight or less.

In the present invention, the average particle diameter of the hard calcium carbonate as lubricant A is 0.01 to 3 μm, which is less than 0.01 μm, the surface roughness of the film is lowered, so that the friction coefficient is increased, and the running property is lowered. This is because the electronic properties of the furnace are reduced. Preferably it is 0.2-2.0 micrometers.

In addition, the amount of the lubricant is added to 0.01 to 4% by weight, preferably 0.05 to 2% by weight. This is because the addition of less than 0.01% by weight of the running friction coefficient is poor workability, when the addition of more than 4% by weight coarse particles due to the flocculation phenomenon of the lubricant is produced when the dropout phenomenon occurs when manufacturing the magnetic tape.

The average particle diameter of the lubricant B, gamma or delta alumina lubricant, is used in a size of 0.005 to 3㎛, which is less than 0.005㎛ the surface roughness of the film is low, the effect of the present invention is insignificant, and when the film exceeds 3㎛ This is because the surface property is poor at the time of manufacturing the magnetic tape. Preferably it is the range of 0.01-1.5 micrometers.

In addition, the amount of the lubricant is added to 0.01 to 4% by weight, preferably 0.05 to 2% by weight. This is because when the addition of less than 0.05% by weight, the running friction coefficient is high, the workability is poor, when the amount exceeds 4% by weight, the lubricant dispersibility is poor, the physical properties of the film is lowered.

The addition amount of the silane coupling agent used in the present invention is 0.05 to 5% by weight based on the weight of the lubricant, which is less effective than the surface treatment at less than 0.05% by weight, due to the increase in the viscosity of ethylene glycol above 5% by weight This is because the dispersibility is poor and the physical properties of the film are greatly reduced.

In the present invention, the point of introduction of the silane coupling agent in the ethylene glycol slurry should be after mixing and stirring the lubricant, and the reaction temperature is controlled to be stirred in the range of 30 to 160 ° C, but preferably 30 to 120 ° C. Do. If the reaction temperature is less than 30 ° C, the surface treatment effect is lowered, and if the reaction temperature is higher than 160 ° C, rather than agglomeration of the lubricant occurs, it is not good.

In addition, a dispersant may be used to prepare an ethylene glycol slurry containing an inorganic lubricant. For example, it is possible to suitably select and use soluble in ethylene glycol from dispersants such as acryl-based compounds such as sodium polyacrylate, sodium methacrylate, and ammonium acrylate and benzenesulfonate-based compounds.

PEN of the present invention is preferably PEN obtained by condensation polymerization of at least 80 mol% of dimethyl-2,6-naphthalate and ethylene glycol, but copolyesters containing a third substance at 10 mol% or less can be used. .

In addition, the PEN of the present invention preferably has a one-step condensation polymerization reaction at a temperature of 270 to 300 ° C. and a pressure of 500 to 30 Torr, followed by a two-step condensation polymerization reaction at a high vacuum of 10 to 0.1 Torr, so that the ultimate viscosity is 0.5 or more. Do.

The production method of the PEN film in the present invention is not particularly limited, but after making the unstretched sheet melt-extruded PEN having a molecular weight of about 20,000 including the above additives by a tee-die method or the like, the biaxially oriented film is biaxially oriented. The PEN film of the present invention is produced.

The stretching method is the same as that of normal PEN stretching, and there is no change of the process by the above additive.

The stretching temperature is preferably 80 to 185 ° C, and the stretching ratio is preferably 2.5 to 6.0 times in the longitudinal direction and the transverse direction, respectively.

PEN films made in accordance with the present invention can be designed in a suitable thickness depending on the application but are typically films ranging from 2.0 to 200 μm.

Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples and the results will be described in detail, but the present invention is not necessarily limited thereto.

The following methods were used for the various performance evaluation of the film manufactured in the Example and comparative example of this invention.

1) Average particle diameter

It is the weight average particle diameter which measured the ethylene glycol slurry using the centrifugal particle size analyzer of Shimadzu Corporation (Japan).

2) viscosity

The viscosity of the slurry was measured at 60 ° C. using a B-type viscometer from Brockfield.

3) molecular weight

Meta-cresol was used as the mobile phase using Waters' molecular weight measuring apparatus, the flow rate was 1 ml / min, and the column temperature was 100 캜 to measure the molecular weight of the polymer.

4) smoothness of surface

The surface roughness of the 15-micrometer-thick film of 30 mm in length and 20 mm in width was measured by the contact type using the surface roughness meter of Kosaka Research Institute (Japan).

Center line average roughness (Ra): When drawing a straight line parallel to the average line of the roughness curve, it is the height of the straight line where both areas of the straight line are equal.

Center line maximum height (R _T ): The distance between the maximum height and the minimum depth in the measurement section.

The lower the average roughness and the maximum height, the better the smoothness and the better the cohesiveness.

5) wear resistance

The tape running tester of Yokohama System Research Institute (Japan) was used, and the tape slitting the film 1/2 inch wide was run at a driving speed of 3.3 cm / sec and two running times, and the surface on the surface of the guide pin was examined with a microscope. Wear resistance was evaluated as the degree of occurrence of white powder around the guide pin during the observation.

◎: When there is no powder on guide pin

○: When one hundredth of the guide pin area is one fifth of the guide pin area

△: 100% of the guide pin area occurs when the guide pin

×: When powder occurs on the guide pin as a whole

6) scratch resistance

The tape running tester of Yokohama System Research Institute (Japan) was used, and the tape slitting the film 1/2 inch wide was run at a driving speed of 3.3 cm / sec and two running times to observe the damaged surface of the film under a microscope. Scratch resistance was evaluated with or without scratch lines around the tape width.

◎: Excellent scratch property (damaged scratch wire is 2 lines or less)

○: Good scratch resistance (damaged scratch wires are 3 to 4 wires)

(Triangle | delta): Scratch-resistant ordinary (damaged scratch lines are 5 to 6 wires)

X: poor scratch resistance (damaged scratch lines are 7 or more lines)

Example 1

Gamma alumina prepared an ethylene glycol slurry containing 20% by weight based on the total weight of ethylene glycol to determine the average particle diameter thereof. Based on the weight of gamma alumina, 0.3% by weight of H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ was added to surface-treat the gamma alumina. The viscosity of the obtained slurry was measured.

The transesterification reaction was carried out by the usual method using dimethyl-2,6-naphthalate and ethylene glycol in a molar ratio of 1 to 2. Here, 0.30% by weight of a hard calcium carbonate having an average particle diameter of 0.42 µm and the ethylene glycol slurry prepared above were added to a polycondensation reaction in a conventional manner to produce a PEN having a molecular weight of about 20,000.

Thereafter, the film was dried, melted, and extruded by a conventional PEN film manufacturing method to prepare an unstretched sheet, and a biaxially stretched PEN film having a thickness of 15 μm was produced by stretching the longitudinal direction and the transverse direction 4.5 times at 140 ° C., respectively, to evaluate the performance.

As can be seen from Table 1, the film obtained by the above method has good surface smoothness, wear resistance, scratch resistance and the like.

EXAMPLES 2-4

A PEN film was prepared in the same manner as in Example 1, but the dosages and average particle diameters of hard calcium carbonate and gamma or delta alumina were varied within a preferred range.

As can be seen from Table 1, the film produced by the above method had various characteristics.

Comparative Examples 1 to 8

The PEN film was prepared by the same method as Examples 1 to 4, but adding at least one inorganic active agent from alumina that was not surface treated with a hard calcium carbonate or a silane coupling agent.

PEN film obtained by the above method was not good in various physical properties as shown in Table 1.

As can be seen from the above, the PEN film prepared by using alumina (alpha, delta) surface-treated with a silane coupling agent according to the present invention includes mechanical properties such as surface smoothness and wear resistance and scratch resistance. It is excellent in the characteristics of various films and can be widely used in various fields such as capacitors, packaging, photographic films, magnetic recording, and industrial use.

Claims (3)

Preparing an ethylene glycol slurry by dispersing gamma or delta alumina having an average particle diameter of 0.005 to 3 μm and a Mohs hardness of 6 or more in ethylene glycol; The gamma or delta alumina was added at a temperature of 30 to 160 ° C. by adding at least one silane coupling agent selected from the group represented by 0.05 to 5 wt% based on the weight of the alumina on the ethylene glycol slurry. Surface treatment; However, in said silane compound, RI is an alkyl group. Condensation polymerization of the surface-treated ethylene glycol slurry and hard calcium carbonate having an average particle diameter of 0.01 to 3 μm into a polyethylene naphthalate monomer obtained by a transesterification reaction; A method for producing a biaxially oriented polyethylene naphthalate film, characterized in that the biaxial stretching by melt extrusion of the polyethylene naphthalate polymer obtained by the polycondensation reaction. The method of claim 1, wherein the alumina is added in an amount of 0.01 to 4% by weight based on polyethylene naphthalate. The method of claim 1, wherein the hard calcium carbonate is added in an amount of 0.01 to 4 wt% based on polyethylene naphthalate.