KR101458230B1 - Polyester film and manufacturing method of the same - Google Patents

Polyester film and manufacturing method of the same Download PDF

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KR101458230B1
KR101458230B1 KR1020090105702A KR20090105702A KR101458230B1 KR 101458230 B1 KR101458230 B1 KR 101458230B1 KR 1020090105702 A KR1020090105702 A KR 1020090105702A KR 20090105702 A KR20090105702 A KR 20090105702A KR 101458230 B1 KR101458230 B1 KR 101458230B1
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South Korea
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layer
resin
film
polyester
copolymer
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KR1020090105702A
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Korean (ko)
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KR20100049497A (en
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김윤조
김동진
김시민
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코오롱인더스트리 주식회사
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00Layered products comprising a layer of synthetic resin
    • B32B27/36Layered products comprising a layer of synthetic resin comprising polyesters
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00Layered products comprising a layer of synthetic resin
    • B32B27/14Layered products comprising a layer of synthetic resin next to a particulate layer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00Properties of the layers or laminate
    • B32B2307/40Properties of the layers or laminate having particular optical properties
    • B32B2307/412Transparent
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2367/00Polyesters, e.g. PET, i.e. polyethylene terephthalate

Abstract

The present invention relates to a polyester film, and more particularly, to a polyester film having a light diffusing property and exhibiting a uniform haze value over the entire surface of the film, and ultimately exhibiting a uniform luminance when applied to an optical film.

Description

[0001] POLYESTER FILM AND MANUFACTURING METHOD OF THE SAME [0002]

The present invention relates to a polyester film, and more particularly to a polyester film which can be used for various displays.

The biaxially stretched polyester film is widely used as a substrate film for optical films because of its excellent transparency, dimensional stability and chemical resistance compared with other plastic films.

In order to effectively utilize light of a light source, a light diffusion layer is coated on a transparent base film as a functional layer. In this case, a separate coating process is required. In addition, in order to maintain predetermined optical properties, The manufacturing cost is very high because a large amount of organic particles must be used.

In addition, there is a problem that the film tends to be deformed and curling is generated by the coating layer in the drying process during coating, resulting in a poor smoothness of the film, and a series of post- In this case, the coating layer is fragile and prone to damage.

In view of this, an attempt has been made to provide light-diffusing properties to the biaxially stretched polyester film itself. An attempt to impart the light diffusing property to the biaxially stretched polyester film itself which has been proposed hitherto has the disadvantage that either one of the inherent characteristics of the biaxially stretched polyester film is lost or that the light diffusing film It is difficult to reach practical use because it loses characteristics to be provided.

For example, Japanese Patent Laid-Open Publication No. 2001-272508 discloses a multilayer type biaxially stretched polyester film using a low-melting-point polyester resin having a melting point of 200 占 폚 or less as a resin constituting the light diffusing layer and a base film made of polyethylene terephthalate . In the method disclosed here, suppression of voids which are expressed around the light-diffusing agent and hinder transparency is considered. Accordingly, a balance between light transmittance and light diffusibility is comparable to that of a conventional light-diffusing film obtained by coating a light diffusing layer made of a transparent resin containing fine particles on the surface of a biaxially stretched polyester film. However, the light-diffusing film obtained by the method described herein has a large melting point difference between the polyester resin constituting the base layer and the polyester resin constituting the light-diffusing layer. The resulting biaxially stretched film has a different coefficient of linear expansion between the light diffusing layer and the base film, so that the biaxially stretched film itself is liable to generate curl upon heat treatment. This may cause curling due to the heat treatment in the post-processing process, or curl may occur depending on the use environment (temperature) of the liquid crystal display, so that there is a possibility that the brightness of the light emitting surface in the backlight unit becomes uneven.

In one embodiment of the present invention, there is provided a biaxially stretched polyester film having a uniform haze value over the entire surface of the film and having light diffusibility in the film itself.

An embodiment of the present invention includes a polyester polymer substrate layer having a surface layer on both faces,

(A) the polyester polymer base layer excluding the surface layer is a polyester resin having a melting point of Tm 1 as a matrix;

(B) the transparent resin matrix comprises 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and a melting point (Tm 2 ) And 20 to 80% by weight of a copolymer resin satisfying Tm 1 - 60 ° C <Tm 2 <Tm 1 - 10 ° C. (C) When the longitudinal section is observed by SEM, (D) the particles contained in each surface layer are different in the average particle diameter from each other among the layers.

According to one embodiment of the present invention, the transparent resin matrix comprises polyethylene terephthalate; A polyester copolymer, a polycarbonate copolymer, and a polysulfone copolymer.

According to an embodiment of the present invention, at least one of the surface layers contains at least one particle having an average particle diameter of 2 to 10 占 퐉, and the other layer contains at least one particle having an average particle diameter of 10 to 30 占 퐉 have.

According to an embodiment of the present invention, the content of particles used in the surface layer may be 0.2 to 15% by weight based on the total weight of the film.

The total thickness of the surface layer may be 5 to 30% of the total film thickness.

The surface layer may also be a layer formed by coextrusion.

Considering optical use, the polyester film of the present invention may have a haze of 60% or more and a total transmittance of 80% or more.

According to another embodiment of the present invention, at least one surface of the polyester film may include a coating layer containing particles having an average particle diameter of 10 to 500 nm dispersed in an acrylic resin or a urethane resin binder. The coating layer may have a thickness of 10 to 1000 nm.

In one embodiment of the present invention, there is provided a method for producing a polyester resin, comprising: a) preparing a polyester resin having a melting point Tm 1 ;

b) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 ° C <Tm 2 <Tm 1 -10 ° C A transparent resin; Compounding at least one light diffusing particle having an average particle diameter of 2 to 10 占 퐉 to produce a first master batch;

c) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 캜 <Tm 2 <Tm 1 -10 캜 A transparent resin; Compounding at least one light-diffusing particle having an average particle diameter of 10 to 30 占 퐉 to produce a second masterbatch;

d) co-extruding a first master batch, a polyester resin and a second master batch on both sides of the polyester resin such that a layer formed from the first master batch and the second master batch is present, to produce an unstretched sheet;

e) stretching the unstretched sheet in the machine direction;

f) stretching the stretched film in the machine direction in the transverse direction; And

g) heat setting the polyester film.

In the production method according to an embodiment of the present invention, a blend of polyethylene terephthalate with at least one copolymer selected from a polyester copolymer, a polycarbonate copolymer and a polysulfone copolymer may be used as the transparent resin .

In the production method according to a preferred embodiment of the present invention, the copolymer resin may include a copolyester obtained from a dicarboxylic acid containing terephthalic acid and a glycol containing neopentyl glycol and ethylene glycol.

In the production method according to an embodiment of the present invention, the machine direction stretching may be performed by stretching the IR-Heater at a temperature of 500 to 900 ° C. so that the stretching ratio is 2.5 to 4.5 times, and the stretching in the width direction may be performed at 105 to 165 ° C. At a stretching ratio of 2.5 to 4.5 times the stretching ratio.

In the production method according to an embodiment of the present invention, the heat setting may be performed by a method of heat treatment at a temperature higher than Tm 2 and lower than Tm 1 .

According to another embodiment of the present invention, there is provided a method for producing a coextrusion sheet, comprising the steps of: preparing a coextruded sheet stretched in the machine direction, at least one side of which has an average particle diameter of 10 to 500 nm, Coating the acrylic resin or urethane resin coating liquid containing the acrylic resin or the urethane resin coating liquid. The inline coating may be performed so that the coating layer thickness after drying is 10 to 1000 nm.

The polyester film according to one embodiment of the present invention includes a polyester polymer base layer having a surface layer on both sides, wherein the meaning of "a polyester polymer base layer having a surface layer on both sides" It will be understood that the polyester polymer base layer itself does not include a surface layer in the form of a separate adhesive layer, lamination layer or coating layer formed on both sides of the polyester polymer base layer, but a surface layer is formed on both surfaces.

According to one embodiment of the present invention, a polyester polymer base layer (hereinafter abbreviated as base layer) excluding a surface layer is a polyester resin having a melting point Tm 1 as a matrix. More specifically, a polyethylene terephthalate (PET) resin is used as a matrix. The polyester resin matrix preferably has a melting point (Tm 1 ) of 230 to 280 ° C in terms of mechanical properties and thermal stability.

(A) a light-diffusing particle dispersed in a transparent resin matrix; (b) the transparent resin matrix comprises 20 to 80 wt% of a homopolyester resin having a melting point of Tm 1 % And a melting point (Tm 2 ) of 20 to 80% by weight of a copolymer resin satisfying Tm 1 - 60 ° C <Tm 2 <Tm 1 - 10 ° C. (C) All have a protruding shape formed by the particles.

The copolymer resin having a melting point (Tm 2 ) contained in the transparent resin matrix constituting the surface layer satisfies a relationship of Tm 1 - 60 ° C <Tm 2 <Tm 1 - 10 ° C. If the melting point (Tm 2 ) is lower than Tm 1 - 60 ° C, the film is deformed due to heat during the stretching in the transverse direction (TD) and heat treatment to aggregate the particles into the edges of the film, When the melting point (Tm 2 ) is in the range of Tm 1 - 10 ° C, it is necessary to perform heat treatment at a high temperature for protruding the particles in the heat treatment zone. Since the particle protrusion on the surface is low, It is difficult to use the film as a film because the mechanical strength is low due to severe degradation of physical properties.

However, when the matrix of the surface layer is formed only of the copolymer resin having the melting point Tm 2 , the matrix of the surface layer is melted due to the melting point difference with the base layer made of the polyester resin matrix having the melting point Tm 1 , The resulting polyester film may have unevenness in haze value over the entire surface thereof. Such unevenness of the haze value over the entire surface of the film may ultimately lead to uneven brightness when applied to optical applications.

In this regard, it is preferable that the transparent resin matrix of the surface layer of the polyester film according to one embodiment of the present invention is made of a copolymer resin having a melting point of Tm 2 and a homopolyester resin having a melting point of Tm 1 .

Specifically, 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 - 60 ° C <Tm 2 <Tm 1 - 10 ° C It is preferable that it is a transparent resin matrix.

More preferably 30 to 50% by weight of a homopolyester resin having a melting point of Tm 1 and 50 to 70% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 - 60 ° C <Tm 2 <Tm 1 - Is a transparent resin matrix.

If the homopolyester resin having a melting point of Tm 1 is less than 20% by weight of the resin matrix constituting the surface layer, it is insufficient to reduce the haze deviation over the entire film. If the homopolyester resin has a melting point exceeding 80% by weight, The brightness may be lowered.

Examples of the copolymer resin having a melting point of Tm 2 include a copolymer selected from a polyester copolymer, a polycarbonate copolymer and a polysulfone copolymer. Among these, a polyester copolymer having a melting point of 180 to 225 ° C Is preferably used since the copolymerized polymer is melted at the time of heat treatment after stretching to form a particle projecting effect the same as that of the coating process on the surface layer. More specifically, a polyester copolymer selected from polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and polytrimethylene terephthalate may be used as the polyester copolymer, and it is also possible to further include additives.

The polyester copolymer is obtained by condensation polymerization of an acid component containing a dicarboxylic acid as a main component and a glycol component containing an alkyl glycol as a main component. As the main component of the dicarboxylic acid, terephthalic acid or an alkyl ester thereof or a phenyl ester thereof is mainly used, but a part of the dicarboxylic acid is converted into a dicarboxylic acid such as isophthalic acid, oxyethoxybenzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, It may be used in place of the functional carboxylic acid or an ester-forming derivative thereof.

As the glycol component, ethylene glycol is a main object, and a part thereof is treated with a solvent such as propylene glycol, trimethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, Bisoxyethoxybenzene, bisphenol, and polyoxyethylene glycol.

On the other hand, each surface layer contains light-diffusing particles, but the average particle diameters of the light-diffusing particles between the respective surface layers are different from each other. Specifically, one of the surface layers may have an average particle diameter of the light-diffusing particles of 2 to 10 mu m and the other surface layer may have an average particle diameter of the light-diffusing particles of 10 to 30 mu m, The light diffusing particles may include at least one kind of particles whose mean particle diameters are different from each other or different from each other.

The reason why the average particle diameter of the light diffusing particles between the surface layers is different is that the optical sheets normally functioning as light diffusing are irradiated with light from the back side of the optical sheet and the anti- In the case of the upper surface, the main role is to increase the luminance. Usually, the smaller the particle size, the higher the diffusion performance, but the lower the transmittance of light.

In consideration of this point, the polyester film according to one embodiment of the present invention is one in which the average particle diameter of the light-diffusing particles is 2 to 10 mu m and the other surface layer is formed such that the average particle diameter is 10 to 30 mu m , When the average particle diameter is less than 2 占 퐉 in one surface layer including the light-diffusing particles having an average particle diameter of 2 to 10 占 퐉, the diffusion property is excellent but the light transmission is difficult, If it exceeds 10 탆, the transmission characteristics are good, but the diffusion performance is poor and it may become difficult to use. When the average particle diameter is less than 10 占 퐉 in one surface layer containing the light-diffusing particles having an average particle diameter of 10 to 30 占 퐉, it is difficult to obtain the optical characteristics of the product requiring light transmission characteristics, , The permeation characteristics are good, but the film may be difficult to be formed due to the drop of the particles due to the friction with the rollers during the film forming process and the breakage due to the deterioration of the stretchability.

The kind of particles is not limited, and organic or inorganic particles can be used. The shape of the particles is not limited, but it may be preferable to use spherical particles in view of optical properties. The particles may be used singly or in combination. As non-limiting examples of the particles include light calcium (CaO), silica sol, barium sulfate (BaSO 4), oxidation of sodium (NaO 2), sodium sulfate (Na 2 SO 4), china clay, anti-blocking of kaolin, talc, etc. Crosslinked acrylic resins and crosslinked polystyrene resins such as inorganic particles, silicone resin, crosslinked divinylbenzene polymethacrylate and crosslinked polymethacrylate, benzoguanamine-formaldehyde resins, benzoguanamine-melamine-formaldehyde resins, melamine- Formaldehyde resin, and the like.

Preferably, it may contain particles such as silicon beads or polymethyl methacrylate beads.

The total content of the particles contained in both surface layers may be advantageous in terms of diffusibility and light transmittance in the range of 0.2 to 15 wt% of the total film weight.

The total thickness of both surface layers may be preferably 5 to 30% with respect to the total film thickness in terms of mechanical properties and optical properties.

The total thickness of the polyester film is not limited, but may be 100 to 250 탆 in consideration of the aspect stability of the coextruded layer.

The surface layer obtained by one embodiment of the present invention is formed on the surface of the base layer such that both the top and bottom surfaces have a protruding shape formed by the particles when the longitudinal section is observed by SEM, The resin composition containing the transparent resin matrix and the light-diffusing particles forming the surface layer is co-extruded and subjected to a stretching process, and a transparent resin matrix constituting the light-diffusible layer is melted Can be achieved by carrying out a heat treatment process including a copolymer resin having Tm &lt; 2 &gt;. The specific process will be described later.

In addition, the polyester film of the present invention may further include a coating layer on at least one surface, if necessary. The additional coating layer may be advantageous from the viewpoint of further improving light transmittance. Specifically, May be an acrylic or urethane coating layer containing particles having an average particle size of 10 to 500 nm. The coating layer may preferably have a thickness of 10 to 1000 nm.

The average particle diameter of the particles included in the coating layer may be within the above range in view of the light transmission property and the anti-blocking effect, and the thickness of the coating layer within the above range may be advantageous in view of the light transmission property and the anti-blocking effect.

There is no particular limitation on the method for forming such a coating layer, but when the coating layer is formed on the film surface through the in-line coating (ILC), the light transmittance can be further improved. For example, in the case of in-line coating, the light transmittance can be increased to about 2% as compared with the case where in-line coating is not performed. The coating solution used for in-line coating is not limited as long as it is a coating solution for forming a polyurethane resin layer having a refractive index of 1.50 to 1.55 or a coating solution for forming an acrylic resin layer having a refractive index of 1.40 to 1.48.

As a composition for forming such a polyurethane resin layer, an ester or carbonate type is generally used as the polyol, an aliphatic isocyanate is used as the isocyanate, and a diol or diamine type as the chain extender. In addition, a coating liquid containing a mixture of methyltetraacrylate, methacrylate, butyl acrylate, acrylic acid and the like can be used as a composition for forming an acrylic resin layer. The binder component used in the coating liquid is preferably in the T g is 20 ℃ ~ 100 ℃, and the coating solution solids content, and 2-10% by weight based on the weight of the coating solution, it is preferable that the viscosity of the coating liquid is not more than 20cps (25 ℃). If the concentration of the solid content is less than 2% by weight, it is necessary to increase the wet application amount to obtain the thickness of the desired coating layer, By weight, the viscosity may increase to 20 cps or more, and the coating property may be lowered.

The polyester film according to the present invention has a haze of 60% or more, more specifically 60 to 99%, a total transmittance of 80% or more, more specifically 80 to 99% Lt; / RTI &gt;

If the haze is less than 60%, the pattern of the light guide plate light source will remain as it is, and the efficiency of changing the front light to the plane light will decrease. If the total transmittance is less than 80%, the brightness may decrease.

Further, a prism film using the optical polyester film according to the present invention is also included in the scope of the present invention. The method for forming the prism film is known, and a prism may be coated on one or both surfaces of the optical polyester film of the present invention by using a coating method commonly used in the field.

An example of a method for producing the above-mentioned polyester film,

a) preparing a polyester resin having a melting point Tm 1 ; b) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 ° C <Tm 2 <Tm 1 -10 ° C Preparing a first master batch by compounding a transparent resin and particles having an average particle diameter of 2 to 10 占 퐉; c) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 캜 <Tm 2 <Tm 1 -10 캜 Preparing a second masterbatch by compounding a transparent resin and light diffusing particles having an average particle diameter of 10 to 30 占 퐉; d) co-extruding the first master batch, the polyester resin and the second master batch such that the first master batch and the second master batch are on both sides of the polyester resin layer to produce an unstretched sheet; e) stretching the unstretched sheet in the machine direction; f) stretching the stretched film in the machine direction in the transverse direction; And g) thermally setting.

After the heat fixing step, a step of relaxing in the machine direction (MD) and the width direction (TD) may be further added. The relaxation can be carried out so as to be 1 to 5% relative to the length of the film, although it is not limited.

After step e), an in-line coating (ILC) step may be further performed on an acrylic or urethane coating solution containing particles having an average particle diameter of 10 to 500 nm. As described above in connection with forming a coating layer on the film surface through in-line coating.

In the machine direction (MD) stretching in step e), the stretching ratio is 2.5 to 4.5 times the temperature of the IR-heater at a temperature of 500 to 900 占 폚. In step f), the stretching in the transverse direction (TD) The stretching ratio is preferably 2.5 to 4.5 times.

When the temperature in the machine direction (MD) stretching is within the above range, it may be advantageous in terms of stretchability and prevention of deformation of the low-melting-point copolymer in the surface layer. Also within this range may be advantageous in that mechanical properties and subsequent widthwise stretching may be possible.

On the other hand, in the stretching in the transverse direction (TD), if the stretching temperature is within the above range, it can be advantageous in terms of preventing breakage and enabling stretching. In addition, the stretching ratio in the width direction (TD) is within the above range, which is advantageous from the viewpoints of physical properties and thickness control, and may be advantageous from the viewpoint of processability.

In addition, heat treatment at a temperature higher than Tm &lt; 2 &gt; and lower than Tm &lt; 1 &gt; may be advantageous in that unevenness can be formed on the surface layer surface of the polyester film. The unevenness thus formed can improve light diffusibility and brightness.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

1) Heat shrinkage

The film was cut in a normal direction of 20 cm x 20 cm to measure the lengths of the film in the machine direction (MD) and the width direction (TD), and then heat shrunk in an oven at 150 캜 for 30 minutes in an oven, The lengths of the heat shrinkable films in the machine direction (MD) and the width direction (TD) were measured, and the heat shrinkage ratios in the machine direction (MD) and the width direction (TD)

<Formula 1>

                 (Length before shrinkage - length after shrinkage)

Heat shrinkage (%) = -------------------------------- × 2 100

                        Length before shrinkage

2)

The film was stretched in the machine direction (direction) of the film by using a universal tensile tester (Instron Tensile Test Machine) with a width of 15 mm, a gauge length of 50 mm and a crosshead-up speed of 500 mm / MD) and the transverse direction (TD).

3) Evaluation of optical characteristics (haze, haze deviation and light transmittance measurement)

The measuring method was based on ASTM D-1003. Seven portions were randomly extracted from two locations on the edge of the polyester film, one at the center, and then cut into a size of 5 cm to 5 cm. The haze was measured with a haze meter (NDH 300A, And haze and total light transmittance were calculated by measuring the haze (%) and the total transmittance (%) of light with a wavelength of 555 nm and calculating an average value for five values excluding the maximum value and the minimum value .

On the other hand, the haze deviation is obtained by calculating the standard deviation of the five values excluding the maximum value and the minimum value among the measured haze values, and the value is represented by the coefficient of variation (CV%), which is a standard deviation value with respect to the average.

<Formula 2>

CV% = standard deviation / haze value average x 2 100

4) Melting Point (Tm) measurement and definition

Put the polymer in liquid nitrogen for 30 seconds, remove it, make it into powder by using a grinder (Hico-10-6-388), and put it into a capillary tube (2 × 2 100 mm). The capillary tube is filled with powdered polymer at a height above the marking line (usually 2/3 or more of the total tube length), placed in a Melting Point measuring instrument (Thomas Hoover Capillary Melting Point Apparatus) / min, the temperature at the melting point of the polymer in the capillary tube is determined from the thermometer and defined as Melting Point (Tm).

[Referential Example 1]

An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point) Homo-polyester (HOMO-PET) of 256 占 폚 was prepared.

Further, it is also possible to use a copolymer obtained by directly condensing 100 mol% of terephthalic acid, 100 mol% of ethylene glycol as a glycol component and 24 mol% of neopentyl glycol with 0.05 mol of antimony trioxide (as acid component) (CO-PET) having a viscosity of 0.67 dl / g, a glass transition temperature of 76 占 폚 and a melting point of 203 占 폚.

Silicone beads having an average particle diameter of 5 탆 were compounded with the copolyester to prepare a first master batch having a particle content of 10% by weight.

Further, a polymethylmethacrylate bead (PMMA bead) having an average particle diameter of 25 占 퐉 was compounded with the copolyester to prepare a second master batch having a particle content of 10% by weight.

The homopolyester was extruded at 275 DEG C, and the first masterbatch and the second masterbatch forming the surface layer were extruded at 270 DEG C, respectively, and a "first masterbatch / base layer / 2 master batch &quot; was 5/85/10 in thickness ratio (A / B / C). At this time, the thickness ratio between the layers was controlled by the discharge amount. The discharged sheet was cooled while passing through a casting roller at 30 ° C to prepare an unoriented film. The unstretched film was stretched 3.5 times in an IR-heater heated at a temperature of 750 ° C in a machine direction machine (MDO) machine which was continuously fed in a mechanical direction. After stretching in the machine direction, the film was stretched to 3.5 times the width at 135 DEG C through a preheating section of 95 DEG C successively, followed by heat treatment at 210 DEG C and 3.5% relaxation at 180 DEG C A film having a thickness of 188 탆 was produced.

[Reference Example 2]

The particle content in the first masterbatch was changed to 50% by weight and the content of the second masterbatch in the second masterbatch was changed to 50% by weight in Reference Example 1, and the content of the "first masterbatch / base layer / A film having a thickness of 188 탆 was prepared in the same manner except that the thickness ratio (A / B / C) was changed to 10/70/20.

[Referential Example 3]

100 mol% of terephthalic acid, 108 mol% of ethylene glycol and 16 mol% of neopentyl glycol as a glycol component, 0.05 mol of antimony trioxide (relative to acid component) as a catalyst, and intrinsic viscosity of 0.67 dl / g, a glass transition temperature of 76 占 폚 and a melting point of 220 占 폚.

Silicone beads having an average particle diameter of 2 탆 were compounded with the copolyester to prepare a first master batch having a particle content of 30% by weight.

Further, polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 20 占 퐉 were mixed at a weight ratio of 9: 1, and this was mixed with the copolyester To prepare a second master batch having a particle content of 30% by weight.

The homopolyester as the resin matrix of the substrate layer was extruded at 275 DEG C using the same material as that of Reference Example 1. The first master batch and the second master batch constituting the surface layer were extruded at 270 DEG C and fed block (A / B / C) of 5/75/20 of the thickness of the "first masterbatch / base layer / second masterbatch" was controlled by controlling the thickness ratio between the layers. (MDO: Machine Direction Organization) was continuously cooled at a temperature of 850 DEG C in a machine direction (MDO) conveyed continuously in a machine direction by cooling the sheet through a casting roller at 30 DEG C to prepare an unstretched film. After the stretching in the machine direction, the film was stretched 3.5 times at 155 DEG C over a preheating section of 95 DEG C successively, and then heat-treated at 235 DEG C , 180 DEG C Applying a relief (Relax) of up to 3.5% to prepare a film having a thickness of 188㎛.

[Reference Example 4]

Silicone beads having an average particle diameter of 2 탆 and silicon beads having an average particle diameter of 5 탆 were mixed at a weight ratio of 7: 3 and compounded with the copolyester of the above-mentioned Reference Example 3, &Lt; / RTI &gt; was prepared.

Polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 15 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 10 占 퐉 were mixed at a weight ratio of 8: 2, and the mixture was mixed with the copolyester To prepare a second master batch having a particle content of 10% by weight.

The same procedure as in Reference Example 3 was carried out except that a sheet having a thickness ratio (A / B / C) of 5/80/15 of "first masterbatch / base layer / second masterbatch" To prepare a film having a thickness of 188 탆.

[Reference Example 5]

100% by mole of terephthalic acid, 97% by mole of ethylene glycol and 27% by mole of neopentyl glycol as a glycol component and 0.05% by mole (based on acid component) of antimony trioxide as a catalyst, dl / g, a glass transition temperature of 74 占 폚 and a melting point of 197 占 폚.

(Silicone Bead) having an average particle diameter of 2 탆 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 10 탆 were mixed at a weight ratio of 9: 1 and compounded with the copolyester to obtain a mixture having a particle content of 5 wt% % &Lt; / RTI &gt;

Further, polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average diameter of 10 占 퐉 were mixed at a weight ratio of 7: 3, And a second master batch having a particle content of 10% by weight was produced by pouring.

The homopolyester as the resin matrix of the substrate layer was extruded at 275 DEG C using the same material as that of Reference Example 1. The first master batch and the second master batch constituting the surface layer were extruded at 270 DEG C and fed to a feed block, , A sheet having a thickness ratio (A / B / C) of 5/88/7 of "first masterbatch / base layer / second masterbatch" was prepared. At this time, the thickness ratio between the layers was controlled by the discharge amount. The discharged sheet was cooled while passing through a casting roller at 30 ° C to prepare an unoriented film. The unstretched film was stretched 3.5 times in an IR-heater heated at a temperature of 600 ° C in a machine direction machine (MDO) machine which was continuously transported in a mechanical direction. After stretching in the machine direction, the laminate was stretched to 3.5 times the width at 125 DEG C through a preheating section of 95 DEG C successively, followed by heat treatment at 210 DEG C and 3.5% relaxation at 180 DEG C A film having a thickness of 188 탆 was produced.

[Referential Example 6]

In the above Reference Example 5, the first master batch and the second master batch were applied to prepare a sheet. The first master batch: homopolyester was mixed with the homopolyester of Reference Example 1 in a weight ratio of 7: 3 (A / B / C) of 5/85/10 of the "first masterbatch / base layer / second masterbatch" was prepared by using the mixture as the first masterbatch.

A film having a thickness of 188 占 퐉 was obtained in the same manner as in Example 5 except that the IR-Heater temperature was 850 占 폚 in the machine direction (MD) stretching and the stretching temperature in the transverse direction (TD) was 145 占 폚 and the heat treatment temperature was 235 占 폚 .

[Example 1]

In the above Referential Example 5, the first masterbatch and the second masterbatch were applied to prepare a sheet. The masterbatches of the above-mentioned Reference Example 1 were mixed in a masterbatch in terms of a weight ratio of the resin matrix of each masterbatch: homopolyester 7 : 3, and applied as a first master arrangement and a second master arrangement. By using this, it was confirmed that the thickness ratio (A / B / C) of "first master arrangement / base layer / second master arrangement" was 5/85/10 Sheet.

A film having a thickness of 188 占 퐉 was obtained in the same manner as in Reference Example 5 except that the IR-Heater temperature was 850 占 폚 in the machine direction (MD) stretching and the stretching temperature in the transverse direction (TD) was 145 占 폚 and the heat treatment temperature was 235 占 폚 .

The thus obtained SEM photograph of the polyester film having the surface layer on both sides measured by the above-mentioned method is shown in Fig.

From Fig. 1, it can be seen that when the longitudinal cross-section is observed by SEM, each layer has a protruding shape formed by the particles on both the top and bottom surfaces.

[Example 2]

Silicone beads having an average particle diameter of 5 탆 were compounded with the copolyester of Reference Example 1 to prepare a first master batch having a particle content of 20% by weight.

Polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉, polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 20 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 15 占Mixed at a weight ratio of 7: 2: 1 and compounded with the copolyester of Reference Example 1 to prepare a second master batch having a particle content of 50% by weight.

In the production of the sheet by applying the first master batch and the second master batch, master batches of the homopolyester of Reference Example 1 were mixed with the homo-polyesters in a ratio of 7: 3 And a sheet having a thickness ratio (A / B / C) of 10/70/20 of the "first masterbatch / base layer / second masterbatch" was prepared in the same manner as in Reference Example 6, A film was prepared.

[Example 3]

(MD), the thickness ratio (A / B / C) of the first masterbatch / base layer / second masterbatch is set to 2/94/4, A film having a thickness of 188 탆 was prepared in the same manner as in Example 1 except that in-line coating (ILC) was performed.

In-line coating (ILC) was prepared by mixing 4 g of an acrylic binder having a refractive index of 1.44, 0.1 g of a silicone-based wetting agent (TEGO polyester siloxane copolymer), 0.1 g of 200 nm colloidal silica particles, a melamine- Ltd.) was added to water as a solvent and stirred for 3 hours to prepare a coating liquid having a solid content concentration of 4.35% and a viscosity of 12 cps at room temperature. The coating liquid was prepared by bar coating (Mayer-Bar application) 2 masterbatch. After coating, the thickness of the wire of the Mayer-Bar was adjusted so that the thickness of the coating layer was 80 nm to prepare a film having a coating layer.

[Example 4]

A film having a thickness of 188 탆 was prepared in the same manner as in Example 2, except that the inline coating was applied to both the first master batch surface and the second master batch surface in the same manner as in Example 2 .

[Example 5]

A film was produced in the same manner as in Example 1 except that the first master batch and the second master batch were produced as described below.

An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point Homo-polyester (HOMO-PET) of 256 DEG C was prepared and used as a resin matrix of the substrate layer.

Further, it was confirmed that an ethylene-propylene copolymer having 100 mol% of terephthalic acid, 97 mol% of ethylene glycol as glycol component and 27 mol% of neopentyl glycol as a glycol and 0.05 mol of antimony trioxide (as acid component) A co-polyester (CO-PET) having a viscosity of 0.67 dl / g, a glass transition temperature of 74 占 폚 and a melting point of 197 占 폚; The same homopolyester as the resin matrix of the base layer was mixed at a weight ratio of 7.5: 2.5. Silicone beads having an average particle diameter of 2 占 퐉 and polymethylmethacrylate beads having an average particle diameter of 10 占 퐉 (PMMA bead) To prepare a first master batch having a particle content of 5% by weight by compounding with mixed particles having a weight ratio of 9: 1.

The copolyester and homopolyester were mixed at a weight ratio of 7.5: 2.5. To the mixture were added polymethylmethacrylate beads (PMMA bead) having an average particle size of 25 占 퐉 and polymethylmethacrylate beads (PMMA bead ) Was mixed with the mixed particles in a weight ratio of 7: 3 to prepare a second master batch having a particle content of 10% by weight.

[Example 6]

A film was prepared in the same manner as in Example 2 except that the first masterbatch and the second masterbatch were produced as described below.

An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point Homo-polyester (HOMO-PET) of 256 DEG C was prepared and used as a resin matrix of the substrate layer.

Further, it is also possible to use a copolymer obtained by directly condensing 100 mol% of terephthalic acid, 100 mol% of ethylene glycol as a glycol component and 24 mol% of neopentyl glycol with 0.05 mol of antimony trioxide (as acid component) A copolyester (CO-PET) having a viscosity of 0.67 dl / g, a glass transition temperature of 76 占 폚 and a melting point of 203 占 폚; The same homopolyester as the resin matrix of the base layer was mixed at a weight ratio of 2.5: 7.5, and a silicone bead (Silicone Bead) having an average particle diameter of 5 탆 was compounded to prepare a first master batch having a particle content of 20% by weight .

The copolyester and the homopolyester were mixed at a weight ratio of 2.5: 7.5. Then, a polymethylmethacrylate bead (PMMA bead) having an average particle diameter of 25 占 퐉 and a polymethylmethacrylate bead (PMMA bead ) And polymethylmethacrylate beads (PMMA beads) having an average particle diameter of 15 탆 were mixed in a weight ratio of 7: 2: 1 to prepare a second master batch having a particle content of 50% by weight.

[Example 7]

In preparing the sheet by applying the first masterbatch and the second masterbatch in Reference Example 5, the homopolyester of Reference Example 1 was masterbatched with the resin matrix of each masterbatch in a weight ratio: homopolyester 6 : 4, and applied as a first master arrangement and a second master arrangement. By using this, the ratio of thickness (A / B / C) of "first master arrangement / base layer / second master arrangement" was 5/85/10 Sheet.

In the same manner as in Reference Example 5, except that in the machine direction (MD) stretching, the IR-Heater temperature was 850 占 폚 and the stretching temperature in the width direction (TD) was 145 占 폚 and the heat treatment temperature was 235 占 폚. A film was prepared.

[Example 8]

Silicone beads having an average particle diameter of 5 탆 were compounded with the copolyester of Reference Example 1 to prepare a first master batch having a particle content of 20% by weight.

Polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉, polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 20 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 15 占Mixed at a weight ratio of 7: 2: 1 and compounded with the copolyester of Reference Example 1 to prepare a second master batch having a particle content of 50% by weight.

In the production of the sheet by applying the first master batch and the second master batch, the master batch of the homopolyester of Reference Example 1 was mixed with the homo polyester in the ratio of 6: 4 by the resin matrix of each master batch And a sheet having a thickness ratio (A / B / C) of 10/70/20 of the "first masterbatch / base layer / second masterbatch" was prepared in the same manner as in Reference Example 6, A film was prepared.

[Examples 9 to 12]

In the above Examples 1 to 4, in the production of the sheet by applying the first masterbatch and the second masterbatch constituting each surface layer, each masterbatch was mixed with the homopolyester of Reference Example 1 at a weight ratio of 5: 5 To prepare a film in the same manner as above except that it was blended.

 [Reference Example 7]

, An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point) Homo-polyester (HOMO-PET) of 256 占 폚 was prepared.

Silicone beads having an average particle diameter of 2 탆 were compounded with the homopolyester to prepare a first master batch having a particle content of 10% by weight.

Further, mixed particles in which polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉 and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 20 占 퐉 were mixed at a weight ratio of 9: 1 were mixed with the homopolyester To prepare a second master batch having a particle content of 20% by weight.

The homopolyester as a resin matrix of the substrate layer was extruded at 275 DEG C and the first master batch and the second master batch constituting the surface layer were extruded at 270 DEG C respectively and fed to the first master batch / Base layer / second master batch &quot; was 5/85/10 in thickness ratio (A / B / C). At this time, the thickness ratio between the layers was controlled by the discharge amount. The discharged sheet was cooled while passing through a casting roller at 30 ° C to prepare an unoriented film. The unstretched film was stretched 3.5 times in an IR-heater heated at a temperature of 850 ° C in a machine direction machine (MDO) conveyed continuously in a mechanical direction. After stretching in the machine direction, the film was stretched to 3.5 times the width at 155 DEG C through a preheating section of 95 DEG C successively, followed by heat treatment at 235 DEG C and a relaxation of 3.5% at 180 DEG C A film having a thickness of 188 탆 was produced.

[Referential Example 8]

After stretching in the machine direction (MD), a film having a thickness of 188 탆 was produced in the same manner as in Reference Example 7, except that in-line coating (ILC) was performed on both sides.

In-line coating (ILC) was prepared by mixing 4 g of an acrylic binder having a refractive index of 1.44, 0.1 g of a silicone-based wetting agent (TEGO polyester siloxane copolymer), 0.1 g of 200 nm colloidal silica particles, a melamine- ) Was added to water as a solvent and stirred for 3 hours to prepare a coating solution having a solid content concentration of 4.35% and a viscosity of 12 cps at room temperature. This was prepared by bar coating (Mayer-Bar application) The master layer and the second master layer. After coating, the thickness of the wire of the Mayer-Bar was adjusted so that the thickness of the coating layer was 80 nm to prepare a film having a coating layer.

[Referential Example 9]

A film having a thickness of 188 占 퐉 was produced in the same manner as in Reference Example 3, except that the heat treatment temperature in Reference Example 3 was 215 占 폚.

[Referential Example 10]

100 mol% of terephthalic acid, 118 mol% of ethylene glycol as glycol component and 6 mol% of neopentyl glycol, 0.05 mol of antimony trioxide (relative to acid component) as a catalyst, and intrinsic viscosity of 0.67 (CO-PET) having a glass transition temperature of 76 ° C and a melting point of 248 ° C was applied as a resin matrix of the surface layer and the heat treatment temperature was 250 ° C. A film having a thickness of 188 탆 was produced in the same manner.

[Referential Example 11]

A film was produced in the same manner as in Example 1 except that the first master batch and the second master batch were produced as described below.

An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point Homo-polyester (HOMO-PET) of 256 DEG C was prepared and used as a resin matrix of the substrate layer.

Further, it was confirmed that an ethylene-propylene copolymer having 100 mol% of terephthalic acid, 97 mol% of ethylene glycol as glycol component and 27 mol% of neopentyl glycol as a glycol and 0.05 mol of antimony trioxide (as acid component) A copolyester (CO-PET) having a viscosity of 0.67 dl / g, a glass transition temperature of 74 캜 and a melting point of 197 캜; Homo-polyesters identical to the resin matrix of the base layer were mixed in a weight ratio of 1: 9, and silicone beads having an average particle size of 2 m and polymethyl methacrylate beads having an average particle size of 10 m (PMMA bead) To prepare a first master batch having a particle content of 5% by weight by compounding with mixed particles having a weight ratio of 9: 1.

The copolyester and homopolyester were mixed in a weight ratio of 1: 9, and polymethylmethacrylate beads (PMMA bead) having an average particle diameter of 25 占 퐉 and polymethylmethacrylate beads (PMMA bead ) Was mixed with the mixed particles in a weight ratio of 7: 3 to prepare a second master batch having a particle content of 10% by weight.

[Referential Example 12]

Except that the first master batch and the second master batch were produced in the same manner as in Example 2, except that the first master batch and the second master batch were produced as described below.

An intrinsic viscosity of 0.64 dl / g, which is obtained by condensation of 100 mol% of terephthalic acid with 124 mol% of ethylene glycol as glycol component and 0.05 mol (based on acid component) of antimony trioxide as a catalyst by direct esterification, Point Homo-polyester (HOMO-PET) of 256 DEG C was prepared and used as a resin matrix of the substrate layer.

Further, it is also possible to use a copolymer obtained by directly condensing 100 mol% of terephthalic acid, 100 mol% of ethylene glycol as a glycol component and 24 mol% of neopentyl glycol with 0.05 mol of antimony trioxide (as acid component) A copolyester (CO-PET) having a viscosity of 0.67 dl / g, a glass transition temperature of 76 占 폚 and a melting point of 203 占 폚; Homo-polyesters identical to the resin matrix of the base layer were mixed at a weight ratio of 9: 1, and a silicone bead (Silicone Bead) having an average particle diameter of 5 탆 was compounded to prepare a first master batch having a particle content of 20% by weight .

The copolyester and the homopolyester were mixed in a weight ratio of 9: 1, and a polymethylmethacrylate bead (PMMA bead) having an average particle diameter of 25 占 퐉 and a polymethylmethacrylate bead (PMMA bead ) And polymethylmethacrylate beads (PMMA beads) having an average particle diameter of 15 탆 were mixed in a weight ratio of 7: 2: 1 to prepare a second master batch having a particle content of 50% by weight.

The above Examples and Reference Examples are summarized in Tables 1 and 2 below.

Figure 112009067679457-pat00001

Figure 112009067679457-pat00002

* Homo-PET: Homopolyester, Co-PET: Polyester copolymer

The physical properties of the films prepared by the above-mentioned Examples, Reference Examples and Comparative Examples were measured and shown in Tables 3 to 4 below.

burglar
(kg / mm2)
Shinto (%) Heat shrinkage (%) Haze (%) Haze deviation
CV (%)
Total light transmittance (%)
MD TD MD TD MD TD room
city
Yes
One 15.8 16.7 201.2 135.6 1.0 0.6 88.3 2.02 90.4
2 15.0 15.5 188.8 125.6 0.9 0.6 89.3 1.87 91.8 3 16.0 16.5 203.2 140.1 0.9 0.6 85.3 1.75 94.2 4 15.1 15.5 192.1 128.1 1.0 0.7 90.5 2.43 93.7 5 15.5 16.4 198.3 130.8 1.1 0.6 87.6 2.15 90.6 6 15.5 15.8 191.3 128.4 1.0 0.6 88.6 1.35 91.6 7 16.2 16.7 205.3 137.2 1.0 0.7 85.0 1.65 93.7 8 15.3 15.7 191.1 125.4 1.1 0.6 88.8 2.13 92.5 9 16.1 16.8 194.2 131.2 1.0 0.5 88.5 1.87 90.1 10 15.3 15.7 185.4 132.2 1.0 0.6 89.7 1.54 91.3 11 16.3 17.1 210.3 133.7 1.0 0.5 86.6 1.34 93.1 12 15.3 15.8 176.8 136.5 0.9 0.5 90.3 1.81 93.5

burglar
(kg / mm2)
Shinto (%) Heat shrinkage (%) Haze (%) Haze deviation
CV (%)
Total light transmittance (%)
MD TD MD TD MD TD Reference example One 15.2 15.6 184.1 123.2 1.7 1.2 45.3 12.27 84.3 2 14.5 15.1 182.4 126.5 1.8 1.1 43.2 18.31 87.9 3 14.6 15.0 170.2 120.1 0.9 0.6 43.2 16.52 90.3 4 14.8 15.0 158.3 120.6 1.0 0.6 47.3 16.89 88.3 5 15.6 15.7 167.6 123.5 1.7 1.0 52.3 11.31 85.5 6 15.0 16.3 200.3 136.2 1.1 0.6 55.2 10.25 88.3 7 16.2 16.9 203.2 141.3 1.0 0.6 88.3 1.23 48.3 8 16.3 16.8 202.4 137.6 1.0 0.7 89.2 1.23 50.5 9 15.3 15.5 180.5 132.1 2.0 1.3 85.3 4.50 45.3 10 10.3 11.2 132.5 87.1 0.7 0.3 12.5 19.37 91.3 11 15.8 16.2 188.3 136.2 1.1 0.6 89.3 2.56 56.3 12 15.0 15.3 183.2 119.1 1.0 0.6 45.3 11.52 89.8

In the case of Reference Examples 1 to 6, since the melting point of the resin used for the light diffusion layer is too low, it is difficult to use particles as an optical film because the particles are gathered around the periphery of the film. In Reference Example 9, The haze is high but the transmittance is low because the particle protruding effect does not appear.

In the case of Reference Example 10, since the melting point of the light-diffusing layer is too high, the heat treatment temperature is increased, so that it is difficult to control the thickness of the film.

In the case of Reference Examples 7 to 8, it can be seen that the heat treatment is performed using the same resin for the base layer and the light diffusion layer, whereby the haze is high but the total light transmittance is low.

In the case of Reference Examples 11 to 12, when the mixed ratio of CO-PET and HOMO-PET is out of a predetermined range, when the CO-PET content is too high, the fixing force of the particles is low, And when the HOMO-PET is excessively high, it is difficult to expect a particle protrusion effect due to the low melting point. Thus, it can be seen that the total light transmittance is low as compared with the case where the appropriate CO-PET and HOMO-PET are mixed.

It can be seen that a light diffusion film having high haze and total light transmittance can be manufactured by providing a light diffusion layer for enhancing the light converging and diffusing function by particle projection on both sides of the film in the light diffusion layer formation.

1 is a SEM photograph of a polyester film obtained from Example 1. Fig.

Claims (17)

  1. A polyester polymer base layer having a surface layer on both sides,
    (A) the polyester polymer base layer excluding the surface layer is a polyester resin having a melting point of Tm 1 as a matrix;
    (B) the transparent resin matrix comprises 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and a melting point (Tm 2 ) And 20 to 80% by weight of a copolymer resin satisfying Tm 1 - 60 ° C <Tm 2 <Tm 1 - 10 ° C. (C) When the longitudinal section is observed by SEM, (D) the particles contained in the surface layer on both surfaces are different in the average particle diameter from each other.
  2. The transparent resin matrix according to claim 1, wherein the transparent resin matrix comprises polyethylene terephthalate; A polyester copolymer, a polyester copolymer, a polycarbonate copolymer and a polysulfone copolymer.
  3. The method according to claim 1, wherein at least one of the surface layers contains at least one kind of particles having an average particle diameter of 2 to 10 μm and the other layer contains at least one kind of particles having an average particle diameter of 10 to 30 μm Polyester film.
  4. The polyester film according to claim 3, wherein the content of particles used in the surface layer is 0.2 to 15% by weight based on the total weight of the film.
  5. 5. The method of claim 4,
    Wherein the total thickness of the surface layer is 5 to 30% based on the total film thickness.
  6. The polyester film according to claim 1, wherein the surface layer is a layer formed by co-extrusion.
  7. 7. The method according to any one of claims 1 to 6,
    A polyester film having a Haze of 60 to 99% and a total transmittance of 80 to 99%.
  8. The polyester film according to claim 1, wherein the polyester film comprises a coating layer comprising particles having an average particle size of 10 to 500 nm dispersed in an acrylic resin or a urethane resin binder on at least one side of the polyester film.
  9. The polyester film according to claim 8, wherein the coating layer has a thickness of 10 to 1000 nm.
  10. a) preparing a polyester resin having a melting point Tm 1 ;
    b) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 ° C <Tm 2 <Tm 1 -10 ° C A transparent resin; Compounding at least one light diffusing particle having an average particle diameter of 2 to 10 占 퐉 to produce a first master batch;
    c) 20 to 80% by weight of a homopolyester resin having a melting point of Tm 1 and 20 to 80% by weight of a copolymer resin having a melting point (Tm 2 ) satisfying Tm 1 -60 캜 <Tm 2 <Tm 1 -10 캜 A transparent resin; Compounding at least one light-diffusing particle having an average particle diameter of 10 to 30 占 퐉 to produce a second masterbatch;
    d) co-extruding a first master batch, a polyester resin and a second master batch on both sides of the polyester resin such that a layer formed from the first master batch and the second master batch is present, to produce an unstretched sheet;
    e) stretching the unstretched sheet in the machine direction;
    f) stretching the stretched film in the machine direction in the transverse direction; And
    g) heat treating the stretched film in the width direction.
  11. A polyester film according to claim 10, wherein a transparent resin is a blend of polyethylene terephthalate and at least one copolymer selected from a polyester copolymer, a polycarbonate copolymer and a polysulfone copolymer. Way.
  12. The process for producing a polyester film according to claim 10, wherein the copolymer resin comprises a copolyester obtained from a dicarboxylic acid containing terephthalic acid and a glycol containing neopentyl glycol and ethylene glycol.
  13. The method of producing a polyester film according to claim 10, wherein the machine direction stretching is performed by stretching the film so that the stretching ratio is 2.5 to 4.5 times the IR-Heater temperature of 500 to 900 캜.
  14. The method for producing a polyester film according to claim 10, wherein the stretching in the transverse direction is performed at a temperature of 105 to 165 캜 so that the stretching ratio is 2.5 to 4.5.
  15. The method of producing a polyester film according to claim 10, wherein the heat setting is performed by a method of heat treatment at a temperature higher than Tm 2 and lower than Tm 1 .
  16. The method according to claim 10, further comprising, before stretching the machine direction stretched film in the machine direction, stretching the machine direction stretched sheet on at least one side of the coextrusion sheet with an acrylic resin or urethane resin containing particles having an average particle size of 10 to 500 nm A method for producing a polyester film, comprising the step of coating the coating liquid in-line.
  17. 17. The method of producing a polyester film according to claim 16, wherein the in-line coating is performed so that the thickness of the coating layer after drying is 10 to 1000 nm.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002178472A (en) 2000-12-13 2002-06-26 Mitsubishi Polyester Film Copp Laminated polyester film
JP2002326330A (en) 2001-05-07 2002-11-12 Mitsubishi Polyester Film Copp Laminated polyester film
KR20040034431A (en) * 2002-10-14 2004-04-28 미쓰비시 폴리에스테르 필름 지엠비에치 Multilayer, biaxially oriented polyester film, process for its production and its use
KR100787368B1 (en) 1999-07-05 2007-12-24 미쯔비시 폴리에스테르 필름 게엠베하 Multilayer, biaxially oriented polyester film and a magnetic recording medium

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100787368B1 (en) 1999-07-05 2007-12-24 미쯔비시 폴리에스테르 필름 게엠베하 Multilayer, biaxially oriented polyester film and a magnetic recording medium
JP2002178472A (en) 2000-12-13 2002-06-26 Mitsubishi Polyester Film Copp Laminated polyester film
JP2002326330A (en) 2001-05-07 2002-11-12 Mitsubishi Polyester Film Copp Laminated polyester film
KR20040034431A (en) * 2002-10-14 2004-04-28 미쓰비시 폴리에스테르 필름 지엠비에치 Multilayer, biaxially oriented polyester film, process for its production and its use

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