KR910009293B1 - Biaxial stretching film having light absorption characteristics - Google Patents

Abstract

The polyester film is produced by ester-exchange reacting dimethyl terephthalate and ethylene glycol with zinc acelate as a catalyst and silica at 140-230 deg.C for 4 hr, polycondsn.-reacting the reactant with antimony trioxide and trimethyl phosphate at 260-285 deg.C for 4 hr to obtain a polyester, dissolving the polyester in the extruder, extruding it through the T-die, cooling it to obtain an amorphous film, longitudinally drawing and biaxially drawing the film, and winding and cutting it. The polyester film has a broad distribution in the surface uneveness.

Description

Biaxially stretched polyester film with excellent matting effect

1 is an enlarged photograph showing surface unevenness in a conventional film.

2 is an enlarged photograph showing surface non-uniformity according to the present invention.

The present invention relates to a biaxially stretched polyester film having an excellent matting effect, and more particularly, to a biaxially stretched polyester film having an excellent matting effect by a surface modification method by particle generation method according to the addition of inorganic particles.

In general, the polyester film is excellent in physical and chemical properties compared to other types of polymer film, and is widely used for packaging, electrical insulation, magnetic tape, and photography.

In particular, polyester film used for drafting, labeling or other display materials require the matting effect to improve the quality of the final product.

Conventional polyester film has a unique gloss, which shows a lot of difference depending on the additive component or surface condition or degree of crystallinity, but the difference is generally fine.

Therefore, in order to remove the gloss of the polyester film, it is important to make a surface on which light can be diffusely reflected as such gloss is due to the specular reflection of light on the film surface.

However, in order to make the film exhibit a matting effect, insoluble inorganic particles are added to the reaction during the polymerization in addition to the sandblasting method, the coating method, and the chemical etching method, or the surface during the polymerization reaction with catalyst or stabilizer components. Although it was modified with phase, the gloss effect was hardly exhibited at 60 ° mirror glossiness of more than 100%.

That is, the polyester film produced by the conventional method has an average surface roughness of 0.03 μm or less, and as shown in FIG. 1 of the accompanying drawings, the surface of the polyester film did not have surface characteristics sufficient to exhibit a matting effect.

Accordingly, the present invention is to solve such problems in the prior art, but to provide a biaxially stretched polyester film having excellent matting effect by modifying the surface properties of the film by using a particle generation method according to the conventional inorganic fine particle addition. .

Hereinafter, the present invention will be described in detail.

The present invention provides a biaxially stretched polyester film obtained by adding a stabilizer component that generates inorganic particles and particles during polyester polymerization, followed by biaxial stretching, wherein the average surface roughness of the film is 0.15 µm to 0.60 µm, and the surface nonuniformity is wide. It is a biaxially stretched polyester film having excellent distribution, characterized in that the 60 ° mirror gloss of the aluminum deposition surface after aluminum deposition is 220% or less, and the gloss of the base film surface is 50% or less.

Hereinafter, the present invention will be described in more detail.

In the present invention, inorganic particles commonly used are added during a polyester polymerization reaction, and the resulting polymer is dissolved in an extruder at 280 ° to 300 ° and extruded into a T-die or an I-die. After cooling to 60 ° to 70 ° C., the amorphous film was heated at a temperature of 80 ° to 110 ° C. at a temperature of 80 ° to 110 ° C. by using a known roll stretching process (preheating part → drawing part → cooling part) using a traveling speed difference between rolls. A polyester film prepared by longitudinally stretching at 4.0 times and transversely stretching at 2.5 to 4.0 times at a temperature of 90 ° to 120 °, wherein the surface roughness of the film has an average of 0.15 μm to 0.60 μm, and the surface characteristics thereof are, for example, Surface non-uniformity is shown as shown in Figure 2 of the accompanying drawings.

Inorganic fine particles used in the present invention can generally be selected from silicon oxide, kaolin, talc, calcium carbonate, mica, titanium dioxide or barium sulfate, the size of which preferably has a particle having an average particle diameter of 0.5㎛ or more Do. The reason is to prevent blocking of the polyester film finally obtained.

As the stabilizer component for producing particles during the polymerization reaction, an alkali or alkaline earth metal compound or a phosphoric acid or phosphorous acid compound and derivatives thereof which are commonly used are preferable.

What is necessary is just to perform the film forming process of the polymer obtained by such a method under the above-mentioned and biaxial stretching conditions, Especially it is preferable to carry out at the high temperature about 2-10 degreeC at the time of longitudinal drawing for the matting effect of a film.

On the other hand, the surface properties of the polyester film produced by the method as described above is to be determined by the surface nonuniformity and the average surface roughness, for example, in the present invention the average surface roughness of the film exhibits 0.15㎛ to 0.60㎛ Surface nonuniformity has an aspect as shown in FIG.

If the average surface roughness is less than 0.15㎛, the matting effect does not appear at all. On the contrary, if the average surface roughness exceeds 0.60㎛, white powder may be generated due to breakage or dropping of the additive during stretching of the film. Is likely to be shortened.

In particular, even if the average surface roughness satisfies the above range, the matting effect is also lowered when the surface unevenness does not have a wide distribution as shown in FIG.

In addition, the polyester film according to the present invention, in addition to satisfying the surface characteristics as described above, when the 60 ° mirror gloss measurement such as ASTM-D-523, the deposition surface gloss after deposition of aluminum is 220% or less, the base film surface gloss is 50 Less than% is displayed.

At this time, if the gloss of the aluminum deposition surface exceeds 220% or if the base film has a gloss of more than 50%, it does not exhibit the desired matting effect in the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Dimethyl terephthalate and ethylene glycol were added at a molar ratio of 1.85, 0.03% by weight of zinc acetate (relative to the polymer) as a transesterification catalyst, 0.8% by weight of sila with a particle size of 2.0 μm as inorganic fine particles were added at 140 ° to 230 ° C. Perform transesterification for 4 hours (methanol is removed at this time), and then perform polycondensation reaction for 4 hours by heating to a range of 260 ° to 285 ° C. under a vacuum of 0.02 mmHg or less, and antimony trioxide as a polycondensation catalyst. The reaction proceeds by adding 0.04% by weight (relative to the polymer) and 0.06% by weight of trimethylphosphate to obtain a polyester having an intrinsic viscosity of 0.60.

It was dried at 150 ° C. for 6 hours, placed in an extruder, dissolved at 290 ° C., extruded through a T-die, cooled on a rotating drum at 60 ° C. to obtain an amorphous sheet of 504 μm, and the layerwise drawing temperature was 100 ° C. and the draw ratio was 2.8 times. Longitudinal stretching is carried out, and then biaxially stretched laterally at a stretching temperature of 110 ° C. and a draw ratio of 3.6 times, followed by winding and cutting to obtain a 50 μm film. Glossiness and operability after aluminum deposition of the film are shown in Table 1 below.

Example 2

It carried out similarly to Example 1 except using 0.1 weight% of calcium acetate and 0.06 weight% of lithium acetate as a transesterification catalyst.

Example 3

It carried out similarly to Example 1 except having biaxially stretched to 110 degreeC of longitudinal stretch temperature, 2.48 times of longitudinal stretch ratio, and 116 degreeC of lateral stretch temperature, and 3.15 times of longitudinal stretch ratio.

Comparative Example 1

It carried out similarly to Example 1 except using 0/8 weight% of the spherical silica of 0.3 micrometer of average particle diameters.

Comparative Example 2

It carried out similarly to Example 1 except having used 0.8 weight% of silicas with an average particle diameter of 2.8 micrometers, and extending | stretching by longitudinal stretch temperature of 116 degreeC, draw ratio 2.2 times, lateral stretch temperature 130 degreeC, and draw ratio 3.0 times.

Comparative Example 3

It carried out similarly to Example 1 except having biaxially stretched to 70 degreeC of longitudinal direction, 3.8 times of longitudinal direction ratio, and 110 degreeC of lateral direction, and 4.5 times of lateral direction.

[Aluminum Deposition Method]

Aluminum was deposited on the base film with a vacuum evaporator in the form of a vacuum of 10 ⁻³ torr or less and capable of heating from 1100 ° to 1300 ° C.

[Assessment Methods]

1. 60 ° C. Mirror gloss: measured by Toseki U-type-gloss meter according to ASTM-D-523.

2. Average surface roughness: Measured with Kosaka ET-10 type surface roughness measuring instrument according to DIN-4768.

3. Surface non-uniformity: Visual observation with 500 times magnification of optical microscope.

4. Production Process: ◎. No breakage, powder generation, or shorter period than filter cycle.

S… Determination, powder generation, any one of the filter cycle shortening occurs.

TABLE 1

Claims (1)

In the biaxially stretched polyester film obtained by adding trimethyl phosphate which generates silica and particles during polyester polymerization followed by biaxial stretching, the average roughness of the film is 0.15 µm to 0.60 µm, and the surface nonuniformity has a wide distribution. An excellent biaxially stretched polyester film having a quenching property of 60% mirror gloss on an aluminum deposition surface after deposition and a gloss on a base film surface of 50% or less.

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