KR19990010183A - Manufacturing method of biaxially oriented polyester film - Google Patents

Abstract

The present invention relates to a method for producing a biaxially oriented polyester film containing a primer coating layer having excellent process permeability, transparency and winding ability by coating a coating liquid containing inorganic particles and organic particles, and an aromatic dibasic acid and ester thereof. A biaxially oriented polyester film was coated by coating a coating bath solution containing 0.01-1 wt% of inorganic particles having an average particle size of 0.001 to 1 μm on a linear saturated polyester synthesized from a forming derivative and a diol or an ester forming derivative thereof. Manufacture.

The polyester film prepared according to the present invention has excellent transparency with less than 1.5% turbidity, and does not have milky appearance after winding with a roll, and can be wound tightly without generation of protrusions due to excellent winding property during slitting work. It is an industrially useful invention.

Description

Manufacturing method of biaxially oriented polyester film

The present invention relates to a method for producing a highly transparent polyester film having excellent coiling properties, and more particularly, to a coating layer containing inorganic particles and organic particles, which contains a primer coating layer which improves process permeability, transparency and winding properties. A method for producing a biaxially oriented polyester film.

Polyester film has excellent physical and chemical properties, mechanical strength, thermal properties, electrical properties, chemical resistance, moisture resistance, water resistance and transparency, and has been widely used as a base material for packaging and industrial use. In order to further secure transparency, a method of securing a certain level of transparency by minimizing the amount of inorganic inert particles added to a polyester film has been disclosed. However, the improvement of film transparency according to such a method is a payment phenomenon. It is accompanied by a problem of lowering productivity due to poor performance.

That is, during winding of the polyester film, protrusions are formed by the close contact between the polyester films, resulting in a poor appearance of the polyester film roll, and a process of processing a product by exposure after coating a photosensitive material on the polyester film. Abnormal refraction of exposure caused by projections in the polyester film is generated to reduce the quality of the product, as well as to prevent the occurrence of projections in the process of cutting and winding to a certain size after the production of the polyester film. Since the air layer formed by mixing is wound while suppressing adhesion between the polyester films, the winding speed is slow, resulting in a decrease in productivity per unit time. In addition, the roll wound by this method is loosely wound and has a problem such that the cross-section omission phenomenon occurs at the center portion of the roll during the process of moving from the product shipment to the post-processing, making the use impossible in the post-processing.

Solving the above disadvantages of productivity and producing a polyester film having high transparency, by applying an external particle method to add an inorganic compound such as titanium dioxide, silicon dioxide, calcium carbonate during polyester polymerization, the activity of the polyester film A method for improving the activity of the polyester film has been proposed, but the method improves the activity of the polyester film. The use amount of the inorganic compound is limited in the field of use of the polyester film. In addition, a method of improving the activity of a polyester film by using fine particles and coarse particles is disclosed in EP-0486225A3, which uses 0.1 to 0.5 μm of silica as fine particles. EP-634452 has two methods, glass beads and CALCINED CLAY, each of which are fine particles and coarse particles. Is disclosed.

However, the polyester film according to the manufacturing method of EP-0486225A3 after the winding, the color of the appearance is milky, the image of the product is degraded, and the method of EP-634452 is not only large coarse particles are likely to fall off, but also of the coating layer There is a disadvantage that the thickness is thick.

Accordingly, an object of the present invention is to provide a method for producing a polyester film having good productivity, excellent winding property and transparency, and no roll appearance and no milky appearance after winding.

In order to achieve the above object of the present invention, polymer particles or water-soluble air containing only inorganic particles or organic particles, styrene sulfonic acid and salts thereof as monomers having a refractive index similar to a polyester resin on one or both surfaces of a polyester film. The present invention has been completed by applying a mixed coating solution of a polyester resin containing not only good winding property but also excellent transparency.

Hereinafter, the present invention will be described in more detail, the polyester film uses a linear saturated polyester synthesized from an aromatic dibasic acid and ester-forming derivatives thereof, in particular, the structural unit of the linear film is 80 mol% ethylene terephthalate unit The saturated polyester resin is melt extruded to contain 0.2% by weight or less of inorganic particles, and an orientation crystallized and heat-treated to make a film in a conventional manner is used. Preferably, the surface roughness of the polyester film is 0.02 μm or less, more preferably 0.01 μm or less, and the light transmittance of the film is 87% or more at a 589 nm wavelength. Such a transparent and smooth film can be obtained by adding a small amount of particles having no particle or small particle diameter to the polyester resin, but the film thickness is usually 5 to 400 µm, preferably 25 to 200 µm. desirable. Obtained a polyester resin having an aromatic particle containing 0.2% by weight or less of an inorganic particle during the polymerization reaction of a linear saturated polyester synthesized from a basic acid, an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, and then dried. After drying sufficiently, the sheet was formed through an extruder, and stretched 3 to 5 times in the longitudinal direction at the stretching temperature of 70 to 150 ° C., followed by adding inorganic particles to the water-soluble copolymer crude solution and coating on one or both sides, and then in the width direction 3 to 5 Stretching is carried out to obtain a polyester film having excellent winding properties and transparency.

Inorganic particles used in the present invention have an average particle diameter of 0.001 to less than 1 μm, preferably 0.01 to 0.5 μm of glass beads, and the glass bead content is preferably 0.01 to 1% by weight or less based on the crude liquid.

If the average particle diameter of the glass beads is 1.0 µm or more, particle dropout occurs and the winding property is significantly reduced.

In this invention, solid content concentration of a water-soluble resin composition is 20 mol% or less, Preferably it is 1-8 mol%, and the viscosity of a coating liquid is 100 cps or less, Preferably it is 20 cps or less. The average coating amount of the coating liquid is 0.01 to 20 g, preferably 0.1 to 10 g / wet per square meter of film. The coating thickness is usually 0.005 to 20 µm, but preferably 0.01 to 2 µm.

As a coating method, a gravure coating method, the roll coating method, the MAYER BAR coating method, the air knife coating method etc. are applied by a well-known method.

Polyester film produced according to the present invention has a thickness of 9 ~ 188㎛, haze (HAZE) is less than 1.5% at a wavelength of 589nm, excellent in transparency, the value of the coefficient of static friction / dynamic friction 0.40 ~ 0.8 / It is 03 ~ 0.60, and the appearance after winding with roll does not have milky appearance, and it is excellent in winding property during slitting work so that it can be wound tightly without the occurrence of protrusion, so it is used in packaging, product protection, building materials, laminate and graphic arts. It is a useful invention that can be used as a base material.

The following examples and comparative examples further illustrate the invention, but the invention is not limited thereto.

Example 1

(A) Preparation of Water-Soluble Copolyester Resin

97 parts of dimethyl terephthalate, 83.42 parts of dimethyl isophthalic acid, 20.7 parts of dimethyl5-sodium isophthalic acid, 124 parts of ethylene glycol, 0.1 parts of zinc acetate dihydrochloride, 0.06 parts of calcium acetate are mixed to remove methanol at 140-220 ° C. After the transesterification reaction, 0.06 parts of trimethyl phosphate, 0.06 parts of antimony trioxide and 7.2 parts of diethylene glycol were added thereto, and the temperature was raised from 240 ° C to 280 ° C for 1 hour. It removed externally and hold | maintained for 40 minutes, and made it react, and obtained the copolyester resin of IV [(eta)] = 0.45. The resin composition of the produced water-soluble copolyester is shown in Table 1.

Table 1

Claims (2)

In preparing a polyester film by applying a coating bath solution to a polyester resin, the coating bath solution of water-soluble copolyester resin contains 0.1 to 1% by weight of glass beads with an average particle diameter of less than 0.001 to 1 µm. Method for producing a biaxially oriented polyester film characterized in that the production The method for producing a biaxially oriented polyester film according to claim 1, wherein the coating bath is prepared by incorporating together silicon or organic particle grass beads.