KR20160038539A - Polyester multi layer film - Google Patents
Polyester multi layer film Download PDFInfo
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- KR20160038539A KR20160038539A KR1020140131744A KR20140131744A KR20160038539A KR 20160038539 A KR20160038539 A KR 20160038539A KR 1020140131744 A KR1020140131744 A KR 1020140131744A KR 20140131744 A KR20140131744 A KR 20140131744A KR 20160038539 A KR20160038539 A KR 20160038539A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
- G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
- G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
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Abstract
Description
More particularly, the present invention relates to a polyester multilayer film which is excellent in surface characteristics, has a low haze and a low haze change rate, is easy to inspect in a post-process, and is small in heat shrinkage and can be applied as an optical film .
Optical films are films used as optical members for displays and are used as optical materials for LCD BLUs or as optical members for surface protection of various displays such as LCDs, PDPs, and touch panels. Such an optical film is required to have excellent transparency and visibility, and a biaxially stretched polyester film excellent in mechanical properties and electrical characteristics is used as a base film.
ITO optical film is used for touch screen, and ITO (Indium Tin Oxide) is coated on polyester film.
The touch screen panel is a panel that does not use an input device such as a keyboard or a mouse but detects a character or a specific position of a human hand or object when the touch is detected and processes a specific function.
The touch screen or the display backlight unit (BLU) uses a UV curing method or a thermosetting drying method. In such a post-processing step, a high temperature of 80 to 130 ° C is applied to the curing process after prism coating, diffusion coating or hard coating, In the process, oligomers migrate from the inside of the polyester film, resulting in whitening of the surface on the surface opposite to the prism coating, diffusion coating, or hard coating, or heat distortion and curling.
Although attempts have been made to lower the oligomer content in the polymerization of the polyester film in order to prevent migration of oligomers of such polyester films, they are insufficient to completely block oligomers.
To solve this problem, the polyester film is aged at a high temperature or a high heat-resistant polymer such as polyethylene naphthalate (PEN) or polyimide (PI) is used. However, when the polyester film is aged at a high temperature, the production yield of the film is not sufficient and deformation due to moisture has occurred. When the high heat resistant polymer is used, heat resistance is remarkably excellent and there is no oligomer migration, The cost of production compared with ester is considerably high and there is a problem that post-processing is difficult.
Japanese Patent Application Laid-Open No. 2007-253511 (2007.10.04) (Patent Document 1) discloses a polyester film having a laminated film on at least one side thereof in order to form a laminated film on a polyester film to control the outflow of oligomer . Having an average size of 10 탆 2 or less in terms of area and a number of 100 or less in a visual field of 100 탆 x 100 탆 in view of the average size of oligomer particles precipitated on the laminated film when the film was heated at 150 캜 for 60 minutes, However, it was not completely blocked and the problem of not controlling the heat shrinkage ratio remained.
Japanese Patent Application Laid-Open No. 2009-279923 (Patent Document 2) discloses a multilayer polyester film excellent in dimensional stability and heat resistance against humidity change and curl-inhibited, and aims to achieve the object by using a copolymerization component . However, according to the patent, the use of a copolymerization component causes a problem that a heat shrinkage is high in a post-processing step, curl is generated in the post-processing due to a difference in shrinkage ratio when the resin is lapped with ITO and the like, There is a fairly expensive problem.
DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a high- The present invention also provides a polyester multi-layer film having such characteristics.
It is another object of the present invention to provide a polyester multilayer film suitable as an optical film including a high-luminance prism film, a protective film for an ITO process, and a base film for ITO.
In order to accomplish the above object, the present invention provides a light emitting device comprising: a substrate layer made of a polyester resin; Wherein the skin layer has an oligomer content of 0.3 to 0.8% by weight and an intrinsic viscosity of 0.65 to 0.8% by weight, Dl / g, wherein the polyester multilayer film has an initial haze (Hi) of 3.0% or less and satisfies the following formulas (1) to (3).
6? Ra? 20 [Formula 1]
80? Rz? 400 [Formula 2]
S MD , S TD ? 0.2 [Formula 3]
In the above formula (1), Ra denotes the surface roughness Ra value (nm) according to the KS B 0161 standard, Rz denotes the surface roughness Rz value (nm) according to the KS B 0161 standard, , S MD means the shrinkage percentage (MD) in the longitudinal direction (MD) of the multilayer film after heat treatment at 90 ° C for 60 minutes, S TD means the shrinkage percentage in the width direction (TD) of the multilayer film after heat treatment at 90 ° C for 60 minutes (%).)
The polyester multilayer film according to an embodiment of the present invention can satisfy the following expression (4).
? H? 0.5 [Formula 4]
(In the formula (4), ΔH is the haze (Hf) measured after the initial haze (Hi) and the heat treatment at 150 ° C. for 30 minutes at a haze change rate calculated by the following formula (1).
[Equation 1]
The thickness of the polyester multilayer film according to an embodiment of the present invention is 25 to 150 탆, the content of the base layer is 70 to 90% by weight of the entire film, and the content of the skin layer is 10 to 30% .
According to one embodiment of the present invention, 10 to 100 ppm of inorganic particles may be contained in the polyester resin constituting the skin layer.
According to an embodiment of the present invention, the inorganic particles may be one or more selected from among silica, zeolite, kaolin, calcium carbonate, titanium oxide, kaolin and barium sulfate having an average particle diameter of 0.5 to 5 μm.
According to an embodiment of the present invention, the polyester multilayered film may satisfy the following formula (5).
0.2? O s / O c ? 0.6 [Formula 5]
(Wherein O s is the oligomer content (wt%) of the skin layer and O c is the oligomer content (wt%) of the base layer).
According to one embodiment of the present invention, the polyester multilayered film may have a coefficient of thermal expansion (CTE) in the longitudinal direction measured using a thermomechanical analyzer (TMA) of 10 to 35 占 퐉 / 占 폚.
According to one embodiment of the present invention, the polyester multilayer film may be an optical film including a high-luminance prism film, a protective film for ITO process, and a base film for ITO.
The polyester multi-layer film according to the present invention has excellent transparency and low haze characteristics suitable as an optical film including a high-luminance prism film, a protective film for ITO process, and a base film for ITO, and can significantly improve heat shrinkage characteristics under high temperature conditions .
In addition, by including 10 to 100 ppm of inorganic particles of 0.5 to 5 占 퐉 in the skin layer of the polyester multilayer film, it is possible to facilitate the inspection in the coating process, thereby improving the convenience of the process. It is possible to prevent the migration of oligomers and to significantly reduce the haze change rate.
1 is a cross-sectional view of a polyester film according to an embodiment of the present invention.
Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments and methods for measuring properties of the polyester multilayer film of the present invention will be described in detail. The present invention may be better understood by the following examples, which are for the purpose of illustrating the present invention and are not intended to limit the scope of protection defined by the appended claims.
As a result of studies to achieve the above object, it has been confirmed that it is an important factor to improve the quality of a film to exhibit low haze, dimensional stability and low migration characteristics of an oligomer. In order to solve such a problem, the inventors of the present invention have found that when at least one skin layer is provided on both sides of a base layer and the oligomer content and the particle size and content of the resin used in the skin layer are controlled, The present invention has been completed.
In order to accomplish the above object, the present invention provides a light emitting device comprising: a substrate layer made of a polyester resin; Wherein the skin layer has an oligomer content of from 0.3 to 0.8% by weight and an intrinsic viscosity of from 0.65 to 0.8% by weight based on the total weight of the polyester layer multilayer film. Dl / g. ≪ / RTI >
The thickness of the polyester multilayer film according to the embodiment of the present invention is preferably 25 to 150 mu m, more preferably 38 to 125 mu m. When the thickness is less than 25 mu m, the mechanical properties suitable for the optical film are not realized. When the thickness exceeds 150 mu m, the thickness of the optical film becomes too thick, which is not suitable for thinning the display device.
It is preferable that the content of the base layer is 70 to 90% by weight of the whole film and the content of the skin layer is 10 to 30% by weight, more preferably the content of the base layer is 70 to 80% Is 20 to 30% by weight, it is effective since it has excellent interface stabilization at the time of pneumatic release and excellent barrier property of oligomer.
The substrate layer of the present invention is not limited as long as it is a transparent polyester resin. For example, it may be polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), and more preferably polyethylene terephthalate (PET) resin alone.
For example, polyethylene terephthalate (PET) contains terephthalic acid and ethylene glycol as polymerization components, and other components (monomers) may be further copolymerized within the scope of not impairing the objects and effects of the present invention.
Other copolymerization components include isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid, succinic acid, adipic acid, sebacic acid, dodecane diacid, dimer acid, maleic anhydride, Dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, mesaconic acid and cyclohexanedicarboxylic acid, oxycarboxylic acids such as 4-hydroxybenzoic acid, epsilon -caprolactone and lactic acid, 1,3 Polyfunctional compounds such as glycols such as propanediol, 1,6-hexanediol and cyclohexanedimethanol, trimellitic acid, trimesic acid, pyromellitic acid, trimethylol propane, glycerin and pentaerythritol.
The polyester containing the polyethylene terephthalate (PET) can be obtained by a known method, for example, a method in which a dicarboxylic acid component and a diol component are directly esterified and then the product of the reaction is heated under reduced pressure to obtain an excess diol component Or a method of polycondensation in the same manner as described above, or a method in which polycondensation is carried out by using a dialkyl ester of a dicarboxylic acid as a dicarboxylic acid component, followed by transesterification reaction with a diol component, . At this time, as the reaction catalyst, for example, alkali metals, alkaline earth metals, manganese, cobalt, zinc, antimony, germanium and titanium compounds may be used as needed, but the present invention is not limited thereto.
In the present invention, the polyester resin constituting the base layer may have an intrinsic viscosity of 0.5 to 1.0 dl / g, more preferably 0.6 to 0.8 dl / g. When the intrinsic viscosity of the substrate layer polyester resin is less than 0.5 dl / g, the heat resistance may be reduced. When the intrinsic viscosity is more than 1.0 dl / g, the multilayer film processability may be deteriorated.
In the present invention, it is effective that the content of the oligomer contained in the base layer is less than 1.4% by weight, preferably 0.1 to 1.4% by weight, more preferably 1.0 to 1.4% by weight. When the content of the substrate layer-containing oligomer is in the above range, the initial haze is low and the haze change rate is not large, and physical properties suitable for the optical film can be realized.
As used herein, the term " oligomer " refers to a low-molecular weight compound which migrates upon heating to dissolve on the surface to cause clouding and thermal deformation, and has a molecular weight of 210 to 7000 g / mol, , dimer, trimer, cyclic type compound. In particular, it is known that a compound such as a cyclic trimer such as the following formula 1 causes a lot of clouding phenomenon.
[Chemical Formula 1]
The skin layer according to an embodiment of the present invention is formed by co-extruding at least two layers on one or both surfaces of a polyester base layer, and may include a polyester resin which is the same as or different from the base layer. More preferably, the skin layer is made of polyethylene terephthalate (PET) alone.
In the present invention, the polyester resin constituting the skin layer may have an intrinsic viscosity of 0.65 to 0.8 dl / g, and more preferably 0.66 to 0.8 dl / g. When the intrinsic viscosity of the polyester resin of the skin layer is less than 0.65 dl / g, the heat resistance may be reduced. When the viscosity is more than 0.8 dl / g, the viscosity of the resin is too high, There is a concern.
In the present invention, it is effective that the content of the oligomer contained in the skin layer is less than 1% by weight, preferably 0.01 to less than 0.8% by weight, more preferably 0.3 to 0.8% by weight. When the content of the oligomer of the polyester resin in the skin layer is within the above range, the initial haze value of the multilayered film is lowered, the rate of change of haze during heat treatment can be reduced, and the problem of curling due to thermal deformation can be prevented , Optical properties and mechanical properties applicable to optical films can be achieved.
The polyester multilayer film of the present invention preferably satisfies the following formula (5).
0.2? O s / O c ? 0.6 [Formula 5]
(Wherein O s is the oligomer content (wt%) of the skin layer and O c is the oligomer content (wt%) of the base layer).
When the oligomer content ratio of the skin layer and the base layer according to an embodiment of the present invention satisfies the above range, since the low oligomer property is exhibited, the initial haze and haze change rates can be lowered more effectively, .
The polyester resin of the skin layer can be produced by a synthesis method obvious from the technical field in order to have an oligomer content within the above range, but in particular, it is effective to reduce the oligomer content by solid phase polymerization.
The polyester resin forming the skin layer preferably contains inorganic particles. It is effective that the inorganic particles contain 10 to 100 ppm of inorganic particles having an average particle diameter of 0.5 to 5.0 탆.
The kind of the inorganic particles is not limited to the inorganic particles used in the technical field of the present invention. For example, one kind or two kinds of inorganic particles selected from silica, zeolite, kaolin, calcium carbonate, titanium oxide, kaolin and barium sulfate Or more can be used. By the addition of such inorganic particles, the polyester multi-layer film of the present invention satisfies the following formulas 1 and 2, thereby improving not only the slip property and the windability in the production process but also the effect of low haze property and heat shrinkage rate So that it is effective.
6? Ra? 20 [Formula 1]
80? Rz? 400 [Formula 2]
(In the above formula 1, Ra denotes the surface roughness Ra value (nm) according to the KS B 0161 standard, and Rz denotes the surface roughness Rz value (nm) according to the KS B 0161 standard.)
When the average particle diameter of the inorganic particles is less than 0.5 占 퐉 or the content is less than 10 ppm, it is difficult to form a sufficient surface roughness, so that a scratch or blocking phenomenon may occur between the films during film production, or the desired property of improving heat shrinkage may become insignificant , When the average particle size of the inorganic particles is more than 5.0 mu m or when the content is more than 100 ppm, the transparency decreases sharply, the surface roughness Ra becomes 20 nm or more, the surface roughness Rz becomes 400 nm or more, The surface of the polyester multilayer film is transferred to the adhesive layer and may not be suitable for optical use, particularly for a touch screen or an ITO process.
If the average particle size exceeds 5.0 탆, the surface smoothness may decrease even if the content is less than 100 ppm. When the inorganic particle content exceeds 50 ppm, even when inorganic particles having an average particle size of 0.5 탆 are used, The transparency is reduced and may not be suitable for optical use.
The surface roughnesses Ra and Rz of the present invention were measured according to the KS B 0161 (surface roughness definition and mark) standard. The surface roughness Ra is an arithmetic mean roughness value obtained by summing the sum of the upper and lower portions at the center line of the reference length and dividing the sum by the length of the measurement section. The surface roughness Rz is a 10- The average of the distance values is obtained from the average line of 5 points in order from the highest mountain and 5 points in order from the deepest point in the order of the average line of all the flat elements within the standard length. Value.
The polyester multilayer film according to one embodiment of the present invention has the advantage of facilitating the inspection during the coating process and increasing the convenience of the process by satisfying the surface roughness values of the above-mentioned formulas 1 and 2. [
The polyester multilayer film according to one embodiment of the present invention preferably has an initial haze (Hi) of 3.0% or less and satisfies the following formula (4).
? H? 0.5 [Formula 4]
(In the formula (4), ΔH is the haze (Hf) measured after the initial haze (Hi) and the heat treatment at 150 ° C. for 30 minutes at a haze change rate calculated by the following formula (1).
[Equation 1]
The initial haze (Hi) is preferably 3.0% or less, more preferably 2.8% or less, as a haze value before the heat treatment. The initial haze is determined by the average size and content of the inorganic particles contained in the skin layer and can be applied as an optical film in a range that satisfies the above range.
The haze (Hf) measured after heat treatment at 150 占 폚 for 30 minutes can be influenced not only by the average size and content of the inorganic particles but also by the oligomer content of the skin layer. When the haze change ratio (H) satisfies the formula (4), it is possible to provide an optical film having a low haze change rate and excellent processing characteristics in a post-process at a high temperature environment.
The polyester multilayer film according to an embodiment of the present invention preferably has a coefficient of thermal expansion (CTE) in the longitudinal direction measured by a thermomechanical analyzer (TMA) of 10 to 35 占 퐉 / 占 폚, more preferably 15 to 25 占 퐉 Mu m / DEG C.
The polyester multi-layer film according to one embodiment of the present invention preferably satisfies the following formula (3).
S MD , S TD ? 0.2 [Formula 3]
(S MD in the formula (3) means the shrinkage (%) in the longitudinal direction (MD) of the multilayer film after heat treatment at 90 ° C for 60 minutes and S TD means the width direction TD). ≪ / RTI >
When the thermal expansion coefficient (CTE) is more than 35 占 퐉 / m 占 폚 and the S MD and S TD are more than 0.2%, thermal deformation occurs severely in the high temperature post-processing step, Due to these problems, there is a problem of curling or heat wrinkling during hard coating or ITO sputtering. In order to solve these problems, a separate off-line aging treatment is required, resulting in more cost and time, So that problems such as scratches and foreign matters are generated in the process.
When the thermal expansion coefficient and the heat shrinkage ratio are within the above range, no curl or heat wrinkling occurs during the hard coating or ITO sputtering process at a high temperature, and an optical film including a high luminance prism film, a protective film for ITO process and a base film for ITO Can be suitably used.
The polyester multi-layer film according to an embodiment of the present invention may further contain various additives in the resin composition constituting the substrate layer or the skin layer within a range that does not impair the physical properties as required. Such additives may include one or more of various additives such as light stabilizers, ultraviolet absorbers and antioxidants, chelating agents, dyes, pigments, viscosity regulators, plasticizers, reinforcing agents, antistatic agents, catalysts and rust inhibitors .
The present invention relates to a method for producing a polyester multilayer film according to an embodiment of the present invention. The production of the polyester multilayer film of the present invention is not limited, but can be obtained by casting after extrusion melt-extrusion in at least two melt extruders and by biaxial stretching. More specifically, the polyester is extruded from one extruder, and the additives such as polyester and inorganic particles such as silica, kaolin, and zeolite are melt-extruded at the same time in another extruder, and then the respective melts meet in the feed block, Cast, cooled, and then biaxially stretched in succession to heat treatment and relaxation. By controlling the stretching, heat treatment and relaxation of these films, it is possible to control the refractive index and shrinkage of the film and the thermal change of the film.
More specifically, a polyester multilayer film according to an embodiment of the present invention
A first polyester resin having an oligomer content of 0.3 to 0.8% by weight and an intrinsic viscosity of 0.65 to 0.8 dl / g forms a skin layer, an oligomer content of 1.0 to 1.4% by weight and an intrinsic viscosity of 0.6 to 0.8 dl / g Co-extruding the polyester multilayered film undrawn sheet so that the second polyester resin as the base layer forms the base layer;
Biaxially stretching the unstretched sheet in the machine direction and the width direction to form a polyester multilayer film; And
And a heat treatment step of loosening the polyester multilayer film in the longitudinal direction and the width direction.
The polyester multilayer film forming step can be produced by biaxially stretching the unstretched sheet. It can be stretched in the longitudinal direction, then stretched in the width direction, and then wound. The stretching ratio is preferably 2.0 to 4.0 times in the longitudinal direction and in the width direction, more preferably 3.0 to 3.5 times in the longitudinal direction and the transverse direction, respectively.
The heat treatment step of the present invention is a step of relaxing in the longitudinal direction and the width direction at a temperature of 200 to 250 ° C, respectively. This heat treatment step is an essential step performed to reduce the heat shrinkage at high temperature during post-processing such as hard coating and ITO sputtering to improve the durability of the polyester multilayer film and to maintain the appearance and optical characteristics of the film surface at an initial stage. The heat treatment method is not limited, but a hot air oven is effective because the damage to the film surface can be minimized.
Further, when curling or heat wrinkling occurs in the polyester multilayer film, an additional process of restoring the surface of the film through separate off-line aging treatment is required. At this time, there is a fear that the process cost and time are consumed excessively, and there is a fear that scratches or foreign matter may increase in such an additional process.
Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.
Property measurement
1. Intrinsic viscosity
0.4 g of PET pellet (sample) was added to 100 ml of a reagent in which phenol and 1,1,2,2-tetrachloroethanol were mixed at a weight ratio of 6: 4, and the mixture was transferred to a Ubero's viscometer. For 10 minutes, and the falling seconds of the solution was determined using a viscometer and an aspirator. The number of drops of the solvent was also determined by the same method, and RV and I.V values were calculated by the following equations (2) and (3).
In the following equation, C represents the concentration of the sample.
&Quot; (2) "
&Quot; (3) "
2. Oligomer content in the film
Oligomer: 0.9 g of the polyester multilayer film sample of the present invention was added to 1 ml of HFIP (1,1,1,3,3,3-hexafluoro-2-propanol) and 1 ml of chloroform in a quantitative manner and dissolved at 25 캜 Then, acetonitrile is added to precipitate a polyester polymer. Then, a calibration curve of a standard substance (cyclic oligomer) is prepared by using an LC analyzer, and the purity of the cyclic oligomer is determined through a sample analysis. Analytical instruments were liquid chromatography (LC) and Agilent 1100 series.
3. HAZE
A sample of the film formed in the above manner was measured using a haze meter (model name: Nipon denshoku, Model NDH 5000).
4. Measurement of oligomer surface migration in film
The initial haze of the film prepared according to an embodiment of the present invention was measured first, and then each of the films measured by c was placed in a box having a height of 3 cm, a width of 21 cm and a length of 27 cm, The oligomer was migrated to the film surface by heat treatment. And the haze value was measured for each hour. The haze value was measured for each hour, and ΔH was calculated using the following equation (1) to measure the surface migration of the oligomer.
<Haze measurement method>
Measuring method: JIS K 715
Measuring equipment: HAZE METER (Nipon denshoku, Model NDH 5000)
[Equation 1]
5. Surface roughness (Ra)
Ra (center line average roughness) and Rz (10-point average roughness) were measured using a three-dimensional non-contact surface roughness meter (NT 2000, WYCO) according to KS B 0161 standard.
6. Measurement of shrinkage after heat treatment
The film was cut 200 mm in the lateral direction and 200 mm in the longitudinal direction, and then heat-treated in a hot air oven at 90 캜 for 60 minutes, and then measured using the following equation.
Shrinkage after heat treatment (%) = (length measured before 90 ° C heat treatment - length after heat treatment after 90 ° C) / 90 ° C length before heat treatment X 100
7. Measurement of Thermal Expansion Coefficient (TMA)
The multilayered film was cut to 16 mm in the longitudinal direction and 4.5 mm in the width direction, and then the temperature was raised at 40 ° C to 160 ° C and 5 ° C / min under 0.05N using TMA (TA corporation) to measure the inflection point Temperature) and thermal expansion coefficient were measured.
[Example 1]
As shown in Table 1, a polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.65 dl / g and an oligomer content of 1.4% was introduced into an extruder as a substrate layer and melt extruded. The skin layer had an intrinsic viscosity of 0.67 dl / (PET) chip with an oligomer content of 0.5% and co-extruded using 80 ppm of inorganic particles (silica) having an average particle size of 1.6 占 퐉 to cast an unoriented sheet. The unstretched sheet was sequentially stretched by 3 times * 3.4 times in the longitudinal and transverse directions, respectively, and heat-treated at 230 占 폚 to prepare a 125 占 퐉 multilayer film. The base layer of the polyester multilayer film was 80% of the total film weight, and the skin layer was 20% of the total film weight. The physical properties of surface roughness, haze, surface oligomer migration, heat shrinkage and thermal expansion coefficient were measured Table 2 shows the results.
[Examples 2 to 11 and Comparative Examples 1 to 8]
Except that the layer composition, the intrinsic viscosity of the skin layer, the oligomer content of the skin layer, the average particle size and the particle size of the skin layer were changed as shown in the following Table 1, A multilayer film was prepared and physical properties of surface roughness, haze, surface oligomer migration, heat shrinkage and thermal expansion coefficient were measured and are shown in Table 2 below.
[Table 1]
(Coextruded with skin layer / base layer / skin layer, and the content of skin layer means the total amount of both skin layers).
[Table 2]
As shown in Table 2, the polyester multi-layer film according to the present invention had a heat shrinkage in the longitudinal direction within 0.15 to 0.18% and a heat shrinkage in the width direction within 0.08 to 0.12% after 90 ° C heat treatment, It was found that it was remarkably superior. In addition, since the surface roughness (Ra) is 9 to 20 nm and the surface roughness (Rz) is 90 to 395 nm, the slip property and the windability are excellent and the haze change rate does not exceed 0.5, And it is found that it is possible to increase the convenience of the process by facilitating the inspection in the coating process.
On the other hand, in Comparative Examples 1 and 4, the haze change rate increases as the oligomer content of the skin layer increases. In Comparative Examples 2 and 3, since the intrinsic viscosity of the skin layer is too high, Was observed.
In Comparative Example 5, the initial haze value was high as the skin layer was formed excessively thick. In Comparative Example 6, the skin layer was formed too thin so that the initial haze was good, but the heat shrinkage and the thermal expansion coefficient were increased, .
In Comparative Example 7, the initial haze was increased, the surface roughnesses Ra and Rz rapidly increased, and the surface of the multilayer film was transferred to the adhesive layer in the subsequent step, resulting in defects such as scratches can do.
Comparative Example 8 showed that although the initial haze value was good and the haze value and the thermal expansion coefficient were relatively increased, the adhesion between the films occurred and the workability and workability were remarkably decreased to be not suitable for the optical film. I could.
Therefore, the objective values of the surface roughness, the initial haze, the haze change rate, the heat shrinkage percentage, and the thermal expansion coefficient can be achieved according to the average particle diameter and the content of the inorganic particles of the skin layer of the polyester multi- It has been found that such a polyester multilayer film is particularly suitable as an optical film including a high luminance prism film, a protective film for ITO process, and a base film for ITO.
While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the above description should not be construed as limiting the scope of the present invention defined by the limits of the following claims.
10: polyester base layer
20: Polyester skin layer
Claims (9)
Wherein the skin layer comprises a polyester resin having an oligomer content of 0.3 to 0.8% by weight and an intrinsic viscosity of 0.65 to 0.8 dl / g,
The polyester multilayer film has an initial haze (Hi) of 3.0% or less and satisfies the following formulas (1) to (3).
6? Ra? 20 [Formula 1]
80? Rz? 400 [Formula 2]
S MD , S TD ? 0.2 [Formula 3]
In the above formula (1), Ra denotes the surface roughness Ra value (nm) according to the KS B 0161 standard, Rz denotes the surface roughness Rz value (nm) according to the KS B 0161 standard, , S MD means the shrinkage percentage (MD) in the longitudinal direction (MD) of the multilayer film after heat treatment at 90 ° C for 60 minutes, S TD means the shrinkage percentage in the width direction (TD) of the multilayer film after heat treatment at 90 ° C for 60 minutes (%).)
Wherein the polyester multilayer film satisfies the following formula (4).
? H? 0.5 [Formula 4]
(In the formula (4), ΔH is the haze (Hf) measured after the initial haze (Hi) and the heat treatment at 150 ° C. for 30 minutes at a haze change rate calculated by the following formula (1).
[Equation 1]
Wherein the thickness of the polyester multilayer film is 25 to 150 占 퐉, the content of the base layer is 70 to 90% by weight of the entire film, and the content of the skin layer is 10 to 30% by weight.
Wherein the skin layer comprises 10 to 100 ppm of inorganic particles relative to the polyester resin constituting the skin layer.
Wherein the inorganic particles are at least one selected from silica, zeolite, kaolin, calcium carbonate, titanium oxide, kaolin and barium sulfate having an average particle diameter of 0.5 to 5 占 퐉.
Wherein the substrate layer comprises a polyester resin having an oligomer content of 0.1 to 1.4 wt% and an intrinsic viscosity of 0.5 to 1.0 dl / g.
Wherein the polyester multilayer film satisfies the following formula (5).
0.2? O s / O c ? 0.6 [Formula 5]
(Wherein O s is the oligomer content (wt%) of the skin layer and O c is the oligomer content (wt%) of the base layer).
Wherein the polyester multilayered film has a coefficient of thermal expansion (CTE) in the longitudinal direction of 10 to 35 占 퐉 / 占 폚 as measured using a thermomechanical analyzer (TMA).
The polyester multilayer film is an optical film comprising a high-luminance prism film, a protective film for ITO process, and a base film for ITO.
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| KR1020140131744A KR20160038539A (en) | 2014-09-30 | 2014-09-30 | Polyester multi layer film |
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| KR1020140131744A KR20160038539A (en) | 2014-09-30 | 2014-09-30 | Polyester multi layer film |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180000929A (en) * | 2016-06-24 | 2018-01-04 | 코오롱인더스트리 주식회사 | Polyester multi-layer film and manufacturing method thereof |
| WO2018062816A1 (en) * | 2016-09-29 | 2018-04-05 | 코오롱인더스트리 주식회사 | Multilayer polyester film and method for producing same |
| KR20180077585A (en) * | 2016-12-29 | 2018-07-09 | 코오롱인더스트리 주식회사 | Biaxial stretched polyester film and manufacturing method thereof |
| CN114806093A (en) * | 2021-01-29 | 2022-07-29 | 南亚塑胶工业股份有限公司 | Polyester mist mask and manufacturing method thereof |
-
2014
- 2014-09-30 KR KR1020140131744A patent/KR20160038539A/en not_active Application Discontinuation
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20180000929A (en) * | 2016-06-24 | 2018-01-04 | 코오롱인더스트리 주식회사 | Polyester multi-layer film and manufacturing method thereof |
| WO2018062816A1 (en) * | 2016-09-29 | 2018-04-05 | 코오롱인더스트리 주식회사 | Multilayer polyester film and method for producing same |
| KR20180035341A (en) * | 2016-09-29 | 2018-04-06 | 코오롱인더스트리 주식회사 | Polyester multi-layer film and manufacturing method thereof |
| KR20180077585A (en) * | 2016-12-29 | 2018-07-09 | 코오롱인더스트리 주식회사 | Biaxial stretched polyester film and manufacturing method thereof |
| CN114806093A (en) * | 2021-01-29 | 2022-07-29 | 南亚塑胶工业股份有限公司 | Polyester mist mask and manufacturing method thereof |
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