KR20170008951A - Mono-layer Polyester film having UV and IR stability - Google Patents

Abstract

The present invention relates to a photostable polyester film having a monolayer structure. The polyester film comprises 94-99 wt% of polyester, 0.01-5 wt% of a photostabilizer, and 0.01-1 wt% of a carbon-based filler.

Description

[0002] Monolayer polyester films having ultraviolet and infrared stability [0003]

The present invention relates to a single-layered solar control film which is widely used for building materials, decorative materials, interior, electronic products, etc., and is mainly attached to the outer surface of glass to protect the inside from ultraviolet rays and infrared rays and protect privacy through coloring .

BACKGROUND ART [0002] Recently, an ultraviolet screening film is attached to a window of a home, an office, or a vehicle for the purpose of shielding ultraviolet rays transmitted through glass such as a transportation means or a building. In addition, by attaching an ultraviolet ray shielding film to a window, it is possible to reduce the amount of heat inflow into the room by reducing the cooling and heating cost due to the air control burden, and by increasing the transmittance of the visible ray, A number of technologies are currently under development for Weihai Solar Control films.

Generally, the solar control film is made of polyester typified by polyethylene terephthalate (PET) and is used not only for blocking sunlight but also for safety enhancement for glass due to strong mechanical properties of PET. Therefore, Also known as a safety film.

An important factor in the production of the solar control film is the ability to absorb visible light of a specific wavelength range to develop a color, and to select dyes or pigments with high durability, as well as to select materials and other additives capable of enhancing cooling and heating efficiency And the compatibility with the applied resin.

In order to exhibit such physical properties, a conventional method is to use a dyed base film or to separate the adhesive layer from an insoluble pigment by milling. Korean Patent Laid-Open No. 10-2012-0061483 also discloses a multilayer polyurethane film which is further provided with a thermoplastic polyurethane layer containing an ultraviolet screening agent on one surface exposed to ultraviolet rays. In Korean Patent Laid-Open No. 10-2012-0073753, Discloses an infrared intercepting multilayer film comprising a reflective layer and a protective layer protecting the reflective layer, wherein two or more film stacks of different areas are laminated.

However, such a solar control film has a laminated structure, and each layer has functions such as UV blocking, IR blocking, antistatic and coloring, and the functional layer must be bonded to form a multilayer structure. That is, since the step of adhering the multilayer film layers is further included, the manufacturing process is complicated and prolonged, and accordingly the price of the film is inevitably increased. In addition, when the film surface coating method is mainly adopted to provide the UV shielding function, the physical properties of the solar control film due to UV curing will be accompanied.

Therefore, there is an urgent need to develop a solar control film which can effectively block the harmful sunlight while improving the disadvantages of such processes, and describe the role of protection against accident or impact.

Korean Patent Laid-Open No. 10-2012-0061483 (June 13, 2012) Korean Patent Laid-Open No. 10-2012-0073753 (Jul. 05, 2012)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a polyester single-layer film capable of simultaneously shielding ultraviolet rays and infrared rays while having a privacy protection function, and a method of manufacturing the same.

It is another object of the present invention to provide a single-layer polyester film and a method for producing the same, which do not require UV curing or the like in addition to the above-mentioned functions, and which can be manufactured in a simple and simple manner at a low cost.

The present invention relates to a polyester film having a single-layer structure and a method for producing the same.

One aspect of the present invention is a light stable polyester film having a monolayer structure, wherein the polyester film is a polypropylene film comprising 94 to 99% by weight of a polyester, 0.01 to 5% by weight of a light stabilizer, and 0.01 to 1% To an ester film.

In the present invention, the light stabilizer may be any one or two or more selected from the group consisting of benzophenone, benzotriazole and benzoate, and the carbon-based filler may be carbon black, graphene, carbon nanotube, graphite, Porous carbon, fullerene, artificial diamond, and the like.

In the present invention, 30 to 99 wt% of 100 wt% of the carbon-based filler may be replaced with tungsten oxide.

The present invention also relates to a polyester film which further comprises at least one additive selected from the group consisting of a dispersing agent, a pigment, a plasticizer, a lubricant, a filler, a reinforcing agent and an antioxidant in the polyester film.

The polyester film according to the present invention may have an average light transmittance of less than 2% at 310 to 380 nm and an average light transmittance of less than 70% at 1200 to 2500 nm. The polyester film may have a transmittance of visible light (400 to 800 nm) of 50% or more and a thickness of 50 to 300 탆.

The polyester film according to the present invention has the effect of simplifying the process and reducing the cost by expressing ultraviolet and infrared ray blocking functions capable of being expressed only in a multilayer structure in a single layer structure.

Also, it is possible to provide a single-layer polyester film which does not require the addition of an initiator and does not change the physical properties of the polymer resin, even though it has a single layer structure, can simultaneously have a privacy protection function while blocking ultraviolet rays and infrared rays .

The polyester film according to the present invention can be mass-produced at a low cost by a simple process and can be produced at the same time without deteriorating mechanical properties.

Hereinafter, the present invention will be described in detail with reference to specific examples. It is to be understood, however, 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 appended claims.

Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Also, the singular forms as used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The single-layer polyester film according to the present invention may include polyester, light stabilizer, and carbon-based filler.

In the present invention, the polyester may be a polymer commonly used in the art. For example, dicarboxylic acids such as terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid And at least one dicarboxylic acid component selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane di And at least one copolyester selected from copolyesters obtained from a diol component comprising at least one diol such as methanol.

More specifically, the polyester resin may include at least one polymer selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT) But is not limited thereto.

Further, in the present invention, in order to enhance the hydrolysis resistance of the polyester, it is possible to use those having a small content of oligomers generated during the condensation polymerization. Further, it is also possible to further improve the water-decomposing property by reducing the moisture content and the shrinkage ratio of the polyester by further adding a known heat treatment for improving the hydrolysis resistance to the polyester film.

In the present invention, the polyester may have a melting point of 260 to 270 캜.

The polyester film may also have an intrinsic viscosity of 0.6 to 0.8 dl / g.

In the present invention, the light stabilizer has a higher extinction coefficient than the extinction coefficient of the polyester and absorbs ultraviolet light incident on the film. Light stabilizers can generally dissipate the absorbed energy into heat and improve the light stability of the polyester.

Examples of the light stabilizer used in the present invention may be any one or more selected from the group consisting of benzophenone, benzotriazole, benzoate, salicylate, oxanilide, cyanoacrylate and nickel compounds.

In the present invention, the light stabilizer may be contained in an amount of 0.01 to 5% by weight based on the entire polyester single-layer film composition. If it is added in an amount of less than 0.01% by weight, the desired ultraviolet ray absorbing effect is not sufficiently manifested in the present invention, and if it is added in an amount exceeding 5% by weight, the visibility may be deteriorated and the mechanical properties of the polyester film may be deteriorated.

In the present invention, the carbon-based filler plays a role of absorbing light having a wavelength ranging from a far infrared region, that is, a wavelength ranging from the sun's infrared rays to heat radiation, dissipating the absorbed energy into heat similarly to the light stabilizer, Can be improved.

Examples of the carbon-based filler used in the present invention may be any one or more selected from carbon black, graphene, carbon nanotube, graphite, activated carbon, porous carbon, fullerene and artificial diamond.

The carbon-based filler may have an average particle diameter of 0.001 to 50 mu m. When the thickness is less than 0.001 탆, the dispersion of the particles during film formation may be uneven and the reflection efficiency of the infrared ray may be lowered. When the thickness exceeds 50 탆, the film may act as an impurity in the film and the mechanical properties may deteriorate.

The carbon-based filler may be contained in an amount of 0.01 to 1% by weight based on the entire polyester single-layer film composition. If it is added in an amount of less than 0.01 part by weight, it is difficult to sufficiently exhibit the desired infrared blocking effect in the present invention, and when it is added in an amount of more than 1% by weight, the visible light transmittance of the film may be significantly lowered.

The present invention may further include at least one additive selected from the group consisting of a dispersing agent, a pigment, a plasticizer, a lubricant, a filler, a reinforcing agent and an antioxidant within the range not impairing the physical properties. The additives can be freely adjusted depending on the composition of the film, physical properties, etc., and the present invention is not limited thereto.

In addition, the polyester film according to the present invention may further include tungsten oxide (WO ₃ ) to block light having a wavelength in the near infrared region. The tungsten oxide is excellent in infrared ray absorbing ability and excellent in photo-thermal conversion effect upon laser irradiation. In addition, since the visible light transmittance is superior to that of carbon black, the desired visibility can be sufficiently secured in the present invention.

In the present invention, the average particle diameter of the tungsten oxide may be 0.001 to 5 mu m. When the average particle size is less than 0.1 탆, there is a problem in dispersibility in the production of chips, and it is difficult to sufficiently express the desired infrared absorbing ability in the present invention. When the average particle size exceeds 5 탆, the film may act as an impurity to decrease the mechanical strength.

In the present invention, tungsten oxide may be added in an amount of 30 to 99 wt% of 100 wt% of the carbon-based filler. When it is added in an amount of less than 30% by weight, it is difficult to sufficiently exhibit the infrared blocking ability. When it is added in an amount of more than 99% by weight, the mechanical properties of the film may decrease or the content of the carbon-based filler may be insufficient.

In the present invention,

a) preparing an ultraviolet screening chip by mixing a polyester chip with a light stabilizer;

b) mixing a polyester chip with a carbon-based filler to produce infrared blocking and coloring compounding chips;

c) preparing an unstretched film by mixing and extruding an ultraviolet shielding chip, an infrared shielding and coloring compounding chip and a polyester chip; And

d) stretching the unstretched film;

. ≪ / RTI >

First, the steps a) and b) are intended to increase the dispersibility of the light stabilizer or the carbon-based filler in the polyester film, wherein the polyester chips used in the steps a) and b) It may be the same as or different from the chip.

The composition ratio of the ultraviolet shielding chip or the infrared shielding chip is not limited to the present invention, and can be freely controlled within the range of the content of the light stabilizer and the carbon filler in the entire polyester film.

In the present invention, the steps a) and b) may be performed by a known method. For example, a method in which a polyester, a light stabilizer or a carbon-based filler is put into a ribbon mixer, kneaded, and then melt-extruded using a rotary twin-screw extruder can be used.

Next, the ultraviolet shielding chip, infrared ray blocking and coloring compounding chips and polyester chips may be mixed and extruded to produce an unstretched film. In the present invention, the production method of the unoriented film is not limited. For example, an ultraviolet screening chip, infrared blocking and coloring compounding chips and polyester chips are placed in an extruder, heated to the melting temperature of the polyester, melted, and then cured using a cooling roll while extruding through the tie rod.

Next, the unstretched sheet produced is stretched. This is because it is important to control the stretching ratio of the film because the molecular orientation is performed through stretching and the thermal strain rate, plane orientation coefficient and shrinkage stress of the film can be controlled within the range of the present invention.

As a biaxial stretching method, there is employed a method of obtaining a biaxially stretched film having an orientation degree of a desired film by stretching and heat-treating an unstretched sheet in the machine direction (MD: Machine Direction) and the transverse direction (TD: Transverse Direction) . Among these methods, the MD / TD method in which the film is stretched in the machine direction (MD) and the transverse direction (TD), or the film is stretched in the transverse direction (TD) A biaxial stretching method such as a TD / MD method in which the film is stretched in the machine direction (MD), a simultaneous biaxial stretching method in which a machine direction (MD) and a transverse direction (TD) . In the case of the simultaneous biaxial stretching method, a tenter driven by a linear motor may be used. Further, a multi-stage stretching method may be used in which stretching in the same direction is divided into multiple stages as necessary.

In the present invention, the film stretching magnification at the time of biaxial stretching is preferably 2.5 to 5.0 times, particularly preferably 3.3 to 4.0 times, in the machine direction (MD) and the transverse direction (TD). However, in this case, the draw ratio of the machine direction (MD) and the transverse direction (TD) may be either larger or equal to the same magnification. It is more preferable that the stretching magnification of the machine direction (MD) is 3.0 to 3.8 times and the stretching magnification of the transverse direction (TD) is 3.5 to 4.3 times.

After the stretching, heat treatment (heat fixing) and relaxation of the film can be performed as necessary. At this time, the heat treatment temperature of the film is not limited to the present invention, but is preferably performed at 220 to 245 ° C. If the heat treatment temperature is less than 220 ° C, the film has a high machine direction shrinkage and shrinking stress, which causes excessive creasing due to excessive tension and shrinkage in the post-process, which is difficult to apply. Film production may be difficult.

The polyester film produced according to the present invention has an average light transmittance of less than 2% at 310 to 380 nm and an average light transmittance of less than 70% at 1200 to 2500 nm.

The polyester film produced according to the present invention may have a visible light transmittance of 400 to 800 nm and a visible light transmittance of 50% or more, more preferably 70% or more.

The polyester film produced according to the present invention may have a thickness of 10 to 500 탆.

Since the polyester film produced according to the present invention contains carbon black and tungsten oxide, the shielding ratio of the infrared rays can be effectively improved by increasing the transmittance of the visible light ray, thereby having excellent visibility and blocking effect. In addition, a UV-blocking agent based on benzophenone or benzotriazole can be further added to increase the ultraviolet shielding ratio.

By forming the above materials into a single composition to exhibit ultraviolet and infrared blocking effects, the manufacturing process can be simplified, and the process cost can be reduced, resulting in an economical effect.

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

The physical properties were measured by the following method.

(Light transmittance)

IR spectroscopy, FT-IR / FT-NIR spectrometer with respect to the whole wavelength region, and the ultraviolet ray blocking rate was measured with an average transmittance of 310 to 380 nm, the infrared ray blocking rate was measured with an average transmittance of 1200 to 2500 nm, The visibility was evaluated by an average transmittance of 400 to 800 nm.

[Example 1]

First, 10 wt% of benzotriazole-based ultraviolet stabilizer was added to 90 wt% of polyethylene terephthalate having an intrinsic viscosity of 0.65 dl / g, and the mixture was kneaded at 30 rpm for 10 minutes. Then, The ultraviolet shielding compound chip was prepared by melt extrusion using a twin screw twin screw extruder with a vent hole.

Next, 50 wt% of polyolefin having an intrinsic viscosity [eta] of 3 dl / g and a melting point of 100 DEG C and 50 wt% of carbon black (average particle diameter 27 nm) were prepared and dispersed at room temperature through a high viscosity blender Respectively. Then, a pre-dispersed polyolefin-carbon black composition was mixed with polyethylene terephthalate having an intrinsic viscosity of 0.65 dl / g at a ratio of 20: 80 wt% to prepare an infrared blocking and coloring compounding chip.

Next, an ultraviolet shielding compound chip 10 wt%, an infrared blocking and coloring compounding chip 5 wt%, and an intrinsic viscosity of 0.65 dl / g 85 wt% of polyethylene terephthalate were put in an extruder and melted at 280 캜. Thereafter, an unoriented sheet was produced on a casting roll (cooling roll) at 20 DEG C while extruding through a tread. The film was stretched 3.5 times in the longitudinal direction and 3.9 times in the width direction to finally produce a film having a thickness of 100 占 퐉, a light stabilizer addition amount of 1% by weight, and a carbon-based filler addition amount of 0.5% by weight. The ultraviolet transmittance, infrared transmittance and visibility of the prepared film were measured and are shown in Table 1 below.

This was melted at 280 ° C in an extruder and extruded through a T-die. The sheet was quenched and solidified on a cooling roller having a surface temperature of 20 ° C while being closely adhered to a cooling roller using an electrostatic application method to obtain an amorphous undrawn sheet.

[Examples 2 to 6 and Comparative Examples 1 to 3]

A film was prepared in the same manner as in Example 1, except that the contents of the light stabilizer and the carbon-based filler were changed as shown in the following table. However, in Example 5, tungsten oxide (average particle diameter 27 nm) was substituted for carbon black (average particle diameter 27 nm) in the preparation of infrared blocking and coloring compounding chips, and 50% In the production of infrared blocking and coloring compounding chips, tungsten oxide (average particle diameter 27 nm) was substituted for 80% of the total amount of carbon black added instead of carbon black (average particle diameter 27 nm). The ultraviolet transmittance, infrared transmittance and visibility of the prepared film were measured and are shown in Table 1 below.

[Table 1]

As described above, the polyester film according to the present invention includes the light stabilizer and the carbon-based filler, so that the ultraviolet light transmittance and the infrared light transmittance are remarkably lowered, and the visible light transmittance is high and the visibility is secured. In particular, when tungsten oxide is added in place of the carbon-based filler, the visible transmittance required by the present invention can be secured while lowering the infrared transmittance.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (9)

94 to 99% by weight of a polyester, 0.01 to 5% by weight of a light stabilizer, and 0.01 to 1% by weight of a carbon-based filler. The method according to claim 1,
Wherein the carbon-based filler is any one or two or more selected from carbon black, graphene, carbon nanotube, graphite, activated carbon, porous carbon, fullerene and artificial diamond. The method according to claim 1,
Wherein the light stabilizer is at least one selected from the group consisting of benzophenone, benzotriazole and benzoate. The method according to claim 1,
Wherein the polyester film further comprises at least one additive selected from the group consisting of a dispersant, a pigment, a plasticizer, a lubricant, a filler, a reinforcing agent and an antioxidant. The method according to claim 1,
Wherein the polyester film has an average light transmittance at 310 to 380 nm of less than 2%. The method according to claim 1,
Wherein the polyester film has an average light transmittance at 1200 to 2500 nm of less than 70%. The method according to claim 1,
Wherein the polyester film has a visible light transmittance of 50% or more. The method according to claim 1,
Wherein the polyester film has a thickness of 10 to 500 占 퐉. 3. The method of claim 2,
Wherein 30 to 99 wt% of 100 wt% of the carbon-based filler is replaced with tungsten oxide.