KR100252037B1 - Polyester film and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A white polyester film and its preparation method are provided, to improve the post-processability such as printing, adhesion and evaporation and the flexibility. CONSTITUTION: The polyester film comprises a biaxially drawn film (A layer); a uniaxially drawn film (B layer) which is formed on the any one side of the A layer; and a uniaxially drawn film (C layer) which is formed on the other side of the A layer. The A layer comprises a polyester resin with the limiting viscosity of 0.8-1.0 dl/g, and 5-30 wt% of one or more white inorganic particles with the mean size of 0.1-5.0 micrometers which is selected from TiO2, talc, CaCO3, BaSO4, silica and orthoclase. The B layer comprises a polyester resin with the limiting viscosity of 0.4-0.6 dl/g. The C layer comprises a polyester resin with the limiting viscosity of 0.4-0.6 dl/g, and 0.01-0.1 wt% of one or more fine particles with the mean size of 0.01-0.1 micrometers which is selected from silica, alumina and poly(methyl methacrylate).

Description

Polyester film and its manufacturing method

The present invention relates to a polyester film and a method for manufacturing the same, and more particularly, to a polyester white film having improved post-processability and flexibility, such as printing, adhesion, and deposition, and a method for manufacturing the same.

Currently, substrates used for labels, advertising papers, cards, calendars, and the like generally include paper and a white plastic film, and polyvinyl chloride, polyolefin, polystyrene, and the like are used as the white plastic.

However, in the case of paper, the processability is excellent, and disposal and recycling are convenient, but there are problems such as expensiveness and discoloration or mold generation when used for a long time. Although polyvinyl chloride has excellent flexibility and good workability, its use is limited in some countries due to environmental problems such as chlorine gas generated during combustion. Polyolefin is most environmentally friendly, its use is gradually increasing, but the mechanical properties are not good and there is a problem that scratches are generated due to low surface strength, there is a need to perform post-processing, such as coating. Polystyrene is excellent in processability, but may break in winter.

On the other hand, polyester film represented by polyethylene terephthalate (PET) is physicochemically stable and excellent in mechanical strength, elastic modulus, dimensional stability, planarity, heat resistance, durability, chemical resistance, electrical insulation, etc. It is widely used for magnetic recording media, magnetic recording media, and the like. In addition, the polyester film is made of a white film, such as the flyers, cards, calendars, labels, magnetic recording cards, award papers for printers, award papers for bar code printers, posters, maps, dust-free papers, display boards, white boards, photo papers, Increasingly, the use of copy paper and printed publications for special purposes is increasing.

However, the polyester film has a high transparency and therefore has a poor concealment, and thus has difficulty in being applied to the above-mentioned application. Therefore, while maintaining excellent physical properties of the polyester film, the research for producing a white polyester film with a high transparency and whiteness by lowering the transparency to suit the purpose is active, among which many techniques for using a white filler is known.

For example, Japanese Patent Application Laid-Open No. 62-243120 and Hei 2-206622 and the like added inorganic particles to polyester, Hei 2-185532 and the like used barium sulfate alone, and Hei 3-50241 and the like. The art which mix | blends a barium sulfate and calcium carbonate after mix | blending a polyolefin resin to this is disclosed.

However, the above known technology simply provides an effect of improving the concealability and / or whiteness of the film by applying an inorganic material, but does not provide an effect of improving post-processability and flexibility according to the use.

Accordingly, the technical problem to be achieved by the present invention is to provide a polyester film having excellent concealability, excellent post-processability and good flexibility.

Another object of the present invention is to provide a method for producing the polyester film.

In order to achieve the above technical problem, the present invention, at least one selected from the group consisting of a first polyester resin having an ultimate viscosity of 0.8 ~ 1.0 dl / g and titanium dioxide, talc, sulfide, silica, calcium carbonate, and feldspar, Biaxially oriented film (A layer) containing 5 to 30% by weight of white inorganic particles having an average particle diameter of 0.1 to 5.0 μm relative to the first polyester resin, and uniaxially stretched film (B) laminated on one surface of A layer. Layer), and a uniaxially stretched film (C layer) laminated on the other side of the A layer, wherein the uniaxially stretched film of the B layer is made of a second polyester resin alone having an intrinsic viscosity of 0.4 to 0.6 dl / g. The uniaxially oriented film of the layer C is one or more particles selected from the group consisting of a polyester resin having an intrinsic viscosity of 0.4 to 0.6 dl / g and silica, alumina, and polymethyl methacrylate, and having an average particle diameter of 0.01 to 0.1 μm. It provides a three-layer polyester film comprising 0.01 to 0.1% by weight relative to the second polyester resin.

In the present invention, the thickness of the layer A is preferably 50 to 95% of the total thickness of the polyester film.

In order to achieve the above another technical problem, (a) one selected from the group consisting of titanium dioxide, talc, barium sulfide, silica, calcium carbonate, and feldspar to the first polyester resin having an intrinsic viscosity of 0.8 to 1.0 dl / g Dispersing the white inorganic particles having an average particle diameter of 0.1 ~ 5.0㎛ 5 to 30% by weight based on the first polyester resin, and then melt-extruded at 280 ~ 320 ℃ to form an unstretched sheet at 0 ~ 20 ℃ step;

(b) stretching the unstretched sheet 2 to 5 times in the longitudinal direction at 90 to 120 ° C. to form a base film (layer A);

(c) Silica and alumina to the uniaxially stretched film (B layer) which consists of 2nd polyester resin of the intrinsic viscosity 0.4-0.6 dl / g alone, and the 2nd polyester resin of the intrinsic viscosity 0.4-0.6 dl / g And uniaxially oriented film (C layer) formed by dispersing 0.01 to 0.1 wt% of one or more fine particles having an average particle diameter of 0.01 to 0.1 μm selected from the group consisting of polymethyl methacrylate with respect to the second polyester resin. Placing on the upper and lower surfaces of the base film and sequentially compressing them to form a three-layer sheet;

(d) heat treating the three-layer sheet at 50 to 80 ° C;

(e) stretching the heat-treated three-layer sheet 2 to 5 times in the transverse direction at 100 to 150 ° C. to form a three-layer film;

(f) it provides a method for producing a three-layer polyester film comprising the step of heat-treating the three-layer film at 160 ~ 180 ℃.

The three-layered polyester film according to the present invention has excellent concealability, but also has excellent post-processability such as printing, adhesion, and deposition, and good flexibility.

Hereinafter, the three-layer polyester film and the manufacturing method thereof according to the present invention will be described in detail. In the present invention, the weight percent means based on the corresponding polyester resin unless otherwise specified.

The 3 layer polyester film which concerns on this invention uses the biaxially stretched film (A layer) in which white inorganic particle is disperse | distributed to 1st polyester resin as a base film, and the 2nd poly whose intrinsic viscosity is 0.4-0.6 dl / g The uniaxially oriented film (B layer) made of the ester resin alone and the uniaxially oriented film (C layer) in which the fine particles are dispersed in the second polyester resin having an intrinsic viscosity of 0.4 to 0.6 dl / g are respectively above and below the base film. It becomes the three-layer polyester film structure used as the surface layer of.

In this invention, the 1st and 2nd polyester resin polycondenses the acid component which has aromatic dicarboxylic acid as a representative component, and the glycol component which has alkylene glycol as a representative component.

The aromatic dicarboxylic acid includes dimethyl terephthalate, terephthalate acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, and the like. Among these, dimethyl terephthalate or terephthalic acid is preferable. The alkylene glycol includes ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, hexylene glycol, and the like, of which ethylene glycol is preferable.

The first and second polyester resins of the present invention are composed of ethylene terephthalate produced by at least 70% by weight of the repeating unit by direct esterification of terephthalic acid and ethylene glycol or transesterification of dimethyl terephthalate and ethylene glycol. Homopolyester. It may be copolymerized within the remaining 30% by weight.

As the copolymer component, both an acid component and an alcohol component can be used. As the acid component, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-sodium sulfopropoxyisophthalic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxy Ethanedicarboxylic acid, α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, trimellitic acid, pyromellitic acid, adipic acid, azelaic acid, And bifunctional or polyfunctional aromatic or aliphatic basic acids such as sebacic acid and cyclohexanedicarboxylic acid. Examples of the alcohol component include trimethylene glycol, diethylene glycol, 2,2-dimethyl-1,3-propanediol, tetramethylene glycol, pentamethylene glycol, neopentyl glycol, hexamethylene glycol, cyclohexylene glycol, 1,4- Bifunctional aromatic or aliphatic alcohols such as cyclohexanedimethanol, 5-sodium sulforesosinol, p-xylene glycol, polyethylene glycol and the like.

It is preferable that the intrinsic viscosity of the said polyester resin is 0.8-1.0 dl / g in the case of the 1st polyester resin used for a base film, and 0.4-0.6 dl / g in the case of the 2nd polyester resin used for a surface layer Is preferably. If the intrinsic viscosity is less than 0.4 dl / g, the mechanical strength of the film cannot be maintained, and breakage occurs frequently during film production, which is undesirable such as extremely low productivity. In addition, when it exceeds 1.0 kPa / g, the melt viscosity is so high that the extrusion pressure is excessively increased, such that the extrusion process becomes unstable and gives a lot of pressure to the equipment.

In addition, the intrinsic viscosity of the polyester is different depending on the intended use, the intrinsic viscosity of the first polyester resin of the base film is somewhat high and the intrinsic viscosity of the second polyester resin of the surface layer is lower than that the thickness uniformity and It is preferable in appearance. If the viscosity of the surface layer is higher than that of the base film as the center layer, the first and second polyester resins are entangled with each other during the extrusion process, which is not preferable.

The white inorganic particles added to the base film layer (A layer) of the present invention are one or more selected from the group consisting of titanium dioxide, talc, barium sulfide, silica, calcium carbonate, and feldspar, and have an average particle diameter of 0.1 to 5.0 탆. It is preferable that the content is 5 to 30 weight% with respect to the 1st polyester of a base film. If the average particle diameter is less than 0.1 μm, the concealability is poor. If the average particle diameter is more than 5.0 μm, the filter pressure during extrusion increases, which is not preferable. In addition, when the content of the white fine particles is less than 5% by weight, the concealability is poor, and when the content of more than 30% by weight is a cause of breakage during stretching.

At least one selected from the group consisting of finely divided silica, alumina and polymethyl methacrylate for use in the surface layer (C layer) of the present invention, preferably having an average particle diameter of 0.01 to 0.1 μm and the content of the second polyester It is preferable that it is 0.01 to 0.1 weight% with respect to resin. If the average particle diameter of the fine particles is less than 0.01 μm, the fine particles are aggregated to decrease processability. If the average particle diameter is larger than 0.1 μm, the fine particles cause protrusions on the surface of the film and lower the glossiness of the film, which is not preferable. . In addition, when the content of the fine particles is less than 0.01% by weight, the surface roughness of the film is too low to cause blocking phenomenon between the films, when the content of more than 0.1% by weight, the glossiness of the film is lowered, which is not preferable because it reduces the aesthetics of the film appearance. not.

Each constituent layer of the three-layer polyester film of the present invention includes a known additive such as a heat stabilizer, an electrostatic agent, a crystallization accelerator, an antiblocking agent, a nucleating agent, and the like within the range of not impairing the effects of the present invention. can do.

Next, the manufacturing method of the three-layer polyester film which concerns on this invention is demonstrated.

First, the white inorganic particles are added to the first polyester, and the fine particles are added to the second polyester, respectively.

As the method of adding the additive in the present invention, a method of dispersing in a slurry form during the polymerization reaction may be used. However, a method of preparing a primary mixed resin by compounding melt mixing and remelting and extruding the resin may be used. It is preferable to improve the dispersibility between resins, to increase the uniformity of physical properties of the produced film, and to improve workability. In the latter case, melt mixing is preferably performed using a compounder having two rotating shafts in the same or two directions, and the final temperature at which the resin and the respective additives are injected is 250 to 300 ° C. and the melt mixing is finished. It is preferable to adjust the temperature of the part to 260-320 degreeC. When the temperature is lower than the temperature, the unmelted polyester resin is present, and when the temperature is adjusted to a high temperature, thermal decomposition of the polyester resin is promoted to turn the resin yellow. It is preferable to adjust the rotational speed and the discharge amount of the rotating shaft so that the temperature of the mixed resin discharged is 270 ~ 320 ℃.

The white inorganic particles were added to the first polyester, and then melt-extruded at 280 to 320 ° C. through a first extruder to prepare a melt sheet. The melt sheet was cooled and solidified at 0 to 20 ° C. to give an unstretched sheet. To form. The undrawn sheet is first drawn at a draw ratio of 2 to 5 times in the longitudinal direction at 90 to 120 ° C. to form a base film layer (A layer). On both surfaces of the uniaxially stretched film, a second polyester resin, in which no additives were mixed, was formed as a surface layer (B layer) through a second extruder, and then fine particles were added to the second polyester resin, followed by a third extruder. The coextrusion sheet is formed as the surface layer (C layer) through the through. Since the three-layer sheet formed exhibits warpage, it is heat-treated by staying for 0.1 to 1 second in an annealing roll (BnneBl roll) having a warm air of 50 to 80 ° C. to alleviate this. Next, the three-layer sheet is stretched 2 to 5 times in the transverse direction at 100 to 150 ° C to form a three-layer film, and then heat-treated at 160 to 180 ° C.

At this time, the thickness of the base film layer is preferably 50 to 95% by weight of the total film thickness. If it is less than 50%, concealability cannot be imparted, and if it is more than 95%, breakage becomes more frequent during the stretching process and the film is less flexible.

Corona treatment may be performed on the formed three-layer film to improve surface tension, or post-processability may be improved by applying an acrylic compound, an imine compound, or the like to the surface to improve printability, adhesion, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it goes without saying that the scope of the present invention is not limited to the following examples. In Examples and Comparative Examples of the present invention, various performance evaluation of the produced film was carried out by the following method.

(1) apparent density

The density gradient tube consisting of carbon tetrachloride and n-heptane was maintained at 25 ° C. and evaluated according to the immersion method.

(2) light transmittance

The light transmittance was measured using the haze meter (model name: SEP-H) of Nippon Precision Optical Co., Ltd., and the case where the light transmittance was low was evaluated as being excellent in concealment. At this time, the measurement conditions were the diameter of the sample was 25mm, the scattering angle was 2.5 degrees.

(3) glossiness

Measurement was carried out using a gloss meter (GC-4010) of Gardner Neotek of USA. The reference diameter was black diameter and the measurement angle was 60 degrees.

(4) stiffness

Collect the two ends of a 1-meter film sample cut into 0.5-inch widths, hang them in a spherical shape at 40 ° C for 1 day, and then change the length of the long side to a and the short side to b. Was measured by B / B ', and the smaller the value was, the higher the flexibility was.

(5) appearance

The appearance of the film was deposited to a thickness of 300 kW using gold (Bu) ions and observed with an electron microscope, and the appearance was evaluated in the state of protrusions as follows. The measurement area was 10 cm x 10 cm.

3 or less: ○, 4 to 5: △, 5 or more: ×

(6) productivity

Productivity was evaluated by the number of times the film broke during manufacture.

5 times / day or less: ○, 5 times / day or more: ×

Example 1

After mixing dimethyl terephthalate and ethylene glycol in a 1: 2 equivalent ratio, 0.05 wt% of tributylene titanate was added to the mixture to prepare a polyethylene terephthalate monomer (bis-2-hydroxyethyl terephthalate (BHET)). Formed. Here, 0.02% by weight of trimethyl phosphate and 0.02% by weight of antimony trioxide as a polymerization catalyst were added to complete the polycondensation to prepare a first polyester resin having an intrinsic viscosity of 0.85 dl / g.

After mixing 18 wt% of titanium dioxide having an average particle diameter of 0.5 μm into the first polyester resin in a first extruder, and extruding at 300 ° C. to prepare a melt sheet, the melt sheet was brought into close contact with a 5 ° C. cooling roll. Cool and solidify to form an undrawn sheet. Next, the unstretched sheet was stretched three times in the longitudinal direction at 105 ° C. to form a biaxially stretched base film layer (B ′ layer).

To the second polyester resin having an intrinsic viscosity of 0.48 dl / g, 0.05 wt% of silica having an average particle diameter of 0.08 μm was mixed in a second extruder, and then the second polyester having an intrinsic viscosity of 0.48 dl / g without any additives added thereto. The resin was mixed into a third extruder and then extruded into both surface layers of the biaxially stretched film (A layer) at 300 ° C., respectively, to form a 270 μm three-layer coextrusion sheet. Subsequently, the three-layer sheet was heat-treated for about 0.5 seconds in a hot air bath roll supplied with warm air in an atmosphere of about 60 ° C. to alleviate curvature in one direction depending on melting conditions and resin properties. The three-layer sheet was stretched three times in the transverse direction again at 140 ° C. and heat-treated at 150 ° C. to obtain a three-layer film having a thickness of 30 μm.

The film is excellent in concealment and post-processing properties, and has low flexural strength in the lateral direction, so that the film is very flexible and thus can be used in various applications.

Examples 2-6

A three-layer polyester film was prepared in the same manner as in Example 1, except that the thickness, additives (type, particle size, and amount of additives) of each film layer were adjusted as shown in Table 1 with the overall film thickness fixed at 30 μm. Prepared. As shown in Table 1, the film thus obtained was not only excellent in concealment and post-processing properties, but also low in lateral curvature strength, and was highly flexible, and thus, it was evaluated that it could be used in various applications.

Comparative Examples 1 to 5

A three-layer polyester film was prepared in the same manner as in Example 1, except that the thickness, additives (type, particle size, and amount of additives) of each film layer were adjusted as shown in Table 1 with the overall film thickness fixed at 30 μm. Prepared. As shown in Table 1, the film thus obtained had low flexibility, poor glossiness, poor appearance and productivity when the intrinsic viscosity of the first polyester was lower than 0.8 to 1.0 dl / g. In the case of deviating from ~ 30%, the appearance, productivity, and flexibility were poor. When the thickness ratio of the layer A of the base film layer was less than 50, the concealability was poor and the appearance was poor. When no fine particles were added, the productivity was poor.

division Base film layer (A) Surface layer (B) Surface layer (C) Film properties PET White inorganic particles Thickness ratio PET Particulate density Light transmittance Glossiness Curvature strength Exterior productivity Ultimate viscosity Kinds Particle diameter Amount - Extreme viscosity Kinds Particle diameter Amount Ultimate viscosity unit ㎗ / g - Μm weight% - ㎗ / g - Μm weight% ㎗ / g g / cm 3 % % - - - Example One 0.85 tea 0.5 18 15/20 0.48 room 0.08 0.05 0.48 1.48 41 135 0.82 ○ ○ 2 0.90 mask 3.2 20 13/20 0.52 egg 0.06 0.06 0.52 1.46 39 133 0.79 ○ ○ 3 0.92 sulfur 1.3 15 16/20 0.53 p 0.07 0.03 0.53 1.46 38 141 0.79 ○ ○ 4 0.88 room 0.3 25 15/20 0.51 room 0.05 0.05 0.51 1.49 42 139 0.85 ○ ○ 5 0.95 burnt 0.5 19 15/20 0.53 room 0.03 0.04 0.53 1.48 45 145 0.73 ○ ○ 6 0.95 tablet 4.1 20 15/20 0.53 room 0.03 0.04 0.53 1.45 41 146 0.71 ○ ○ Comparative example One 0.62 tea 0.3 16 15/20 0.75 egg 0.03 0.06 0.75 1.44 32 105 0.91 × × 2 0.85 sulfur 0.6 2 18/20 0.55 room 0.02 0.08 0.55 1.46 71 132 0.78 ○ ○ 3 0.86 room 0.8 20 8/20 0.45 room 0.05 0.06 0.46 1.45 65 135 0.79 △ ○ 4 0.82 tea 3.2 45 16/20 0.56 p 0.06 0.08 0.58 1.46 42 129 0.95 △ × 5 0.85 tablet 3.6 21 15/20 0.52 room 0.05 0 0.46 1.43 45 135 0.81 ○ ×

T: Titanium Dioxide De: Talc Sulfur: Barium Sulfide

Thread: Silica Tan: Calcium Carbonate Tablet: Dressing Stone

Egg: Alumina P: Polymethylmethacrylate

SM: Styrene methacrylate

As described above, the three-layer polyester film according to the present invention is excellent in post-processability such as printing, adhesion, vapor deposition, and the like, and the flexibility is good. Accordingly, the three-layer polyester film according to the present invention is a magnetic card, a label, an award paper for a printer, a barcode paper award paper, a poster, a map, a dust-free paper, a display board, a white board, a photo paper, a copy paper, a printed publication for special use, and the like. Suitable for use.

Claims (4)

At least one white inorganic particle having an average particle diameter of 0.1 to 5.0 μm selected from the group consisting of a first polyester resin having an intrinsic viscosity of 0.8 to 1.0 μg / g and titanium dioxide, talc, sulfide, silica, calcium carbonate, and feldspar To a biaxially stretched film (A layer) containing 5 to 30% by weight relative to the first polyester resin, a uniaxially stretched film (B layer) laminated on one side of the A layer, and the other side of the A layer. A uniaxially oriented film (C layer) laminated, wherein the uniaxially oriented film of layer B is composed of a second polyester resin alone having an intrinsic viscosity of 0.4 to 0.6 dl / g, and the uniaxially oriented film of layer C is extremely The second polyester resin having a viscosity of 0.4 to 0.6 dl / g and at least one fine particle having an average particle diameter of 0.01 to 0.1 μm selected from the group consisting of silica, alumina and polymethyl methacrylate may be used for the second polyester resin. 0.01 Three-layer polyester film with improved flexibility and post-processing, characterized in that containing at 0.1% by weight. The polyester film according to claim 1, wherein the thickness of the layer A is 50 to 95% of the total thickness of the polyester film. (a) at least one average particle diameter selected from the group consisting of titanium dioxide, talc, barium sulfide, silica, calcium carbonate, and feldspar in a first polyester resin having an intrinsic viscosity of 0.8 to 1.0 dl / g; Dispersing the phosphorus white inorganic particles in an amount of 5 to 30% by weight based on the first polyester resin, followed by melt extrusion at 280 to 320 ° C. to form an unstretched sheet at 0 to 20 ° C .; (b) stretching the unstretched sheet 2 to 5 times in the longitudinal direction at 90 to 120 ° C. to form a base film (layer A); (c) Silica and alumina to the uniaxially stretched film (B layer) which consists of 2nd polyester resin of the intrinsic viscosity 0.4-0.6 dl / g alone, and the 2nd polyester resin of the intrinsic viscosity 0.4-0.6 dl / g And uniaxially oriented film (C layer) formed by dispersing 0.01 to 0.1 wt% of one or more fine particles having an average particle diameter of 0.01 to 0.1 μm selected from the group consisting of polymethyl methacrylate with respect to the second polyester resin. Placing on the upper and lower surfaces of the base film and sequentially compressing them to form a three-layer sheet; (d) heat treating the three-layer sheet at 50 to 80 ° C; (e) stretching the heat-treated three-layer sheet 2 to 5 times in the transverse direction at 100 to 150 ° C. to form a three-layer film; (f) a method of producing a three-layer polyester film, comprising the step of heat-treating the three-layer film at 160 to 180 ° C. The method of claim 3, wherein the thickness of the layer A is 50 to 95% by weight based on the total film thickness.