KR20140094960A - Composition with high barrier properties comprising polymer and exfoliated graphite - Google Patents

Abstract

The present invention relates to a composition including a polymer and an exfoliated graphite and having blocking properties of water and gas, a film obtained by coating the composition, and an application of the film in a packaging field. The composition including the polymer and the exfoliated graphite according to the present invention and the film obtained by coating the composition have good blocking properties of water and gas, and can be usefully used for packaging foods, drugs, medical appliances, and electrical and electronic products requiring the blocking of water and gas.

Description

[0001] The present invention relates to a high-barrier composition comprising polymer and exfoliated graphite,

The present invention relates to a composition having moisture and gas barrier properties, including a polymer and peeled graphite, a film coated thereon, and applications in the field of packaging such films.

Barrier is what prevents any substance or energy from being transferred from the system containing it to another system, and a substance with such properties is called a barrier substance. It can be said that factors such as moisture, humidity, oxygen, carbon dioxide, nitrogen, ultraviolet rays, light, microorganism, heat etc. can affect the quality of the target product. In the fields of medicine, medical equipment, A polymer material having a high barrier property against water, oxygen and the like is demanded even under use environment.

BACKGROUND OF THE INVENTION [0002] In the back sheet which functions as a waterproof, insulating and ultraviolet ray shielding in a solar cell module, which is undergoing many researches and commercialization in recent years, the solar cell is corroded by water permeation, There is a tendency that there is a need for a material having high barrier properties which can withstand high temperature and humidity environments and has excellent durability and weatherability.

In the field of flexible display, which is widely regarded as a next generation technology, in order to realize a technology that folds or bends in various forms such as a mobile phone on a wrist, a scroll-shaped electronic book, Instead, transparent and flexible plastic substrates should be used. However, development of high barrier film is very important because most core devices used in flexible displays are limited in practical use due to a rapid decrease in life due to moisture penetration.

In the packaging industry, the transport of moisture and gas (especially oxygen) to packaging products in fresh products such as meat, cheese, and dried foods such as rice flour and confectionary leads to shelf life The need for the development of a high barrier film is increasing. In medicine and medical device packaging, contamination from the external environment such as moisture and gas in the distribution process adversely affects the patient, so that the importance of high barrier packaging is greatly increased.

Consumer and manufacturer requirements for high barrier materials are also increasing. Consumers and manufacturers want to have high barrier properties and at the same time have the following characteristics.

The first is transparency and light (especially ultraviolet) barrier properties. When purchasing a product, the consumer wants to see the product in the package directly, then purchase it, and not be damaged by the light.

The second is stability. Consumers prefer products with thermal stability, cushioning and adhesion because they want to store their products for a long time and want to be simple and long-lasting. Many studies and commercialization of high-barrier materials that meet the needs of these consumers and manufacturers are under way.

The importance of barrier materials considering environmental and economical factors and development need are also emerging. As global environmental issues have emerged as a global concern, enforcement of environmental regulations has continued to be centered on developed countries. Therefore, while maintaining the original function of the product, it is easy to recycle after using the product, designing the product to reduce the use of harmful substances, and uni-material (unified material) Uni Material) is emerging.

Governments and industries in the world also place environmental imperatives in the value chain of materials, components, products, recycling, and processes, while minimizing the environmental impact, as an important element of green design strategies and principles. Particularly, in the packaging industry, there is a growing interest in packaging materials capable of ensuring not only the shelf life of products but also eco-friendly packaging, universal packaging, and economical packaging.

Highly barrier materials that are widely used today include (1) PVDC coating film, (2) aluminum vapor deposition film, (3) a film composed of ethylene vinyl alcohol (EVOH) polymer which does not transmit gas and moisture (Multilayer film), and the like. However, in the case of an aluminum evaporated film or an ethylene vinyl alcohol (EVOH) polymer multilayer film, the price is high, and the barrier property against moisture and gas under high temperature and high humidity is abruptly lowered so that it can not be used alone. Therefore, it is necessary to secure material technology that is both environmentally friendly and economical, satisfying both gas and water barrier properties under various environments.

Among various high barrier materials, ethylene vinyl alcohol (EVOH) polymer is an attractive material which has many researches because it has excellent gas barrier properties, fragrance barrier, transparency and gloss, chemical resistance and printing suitability. Also, it has high surface tension without surface treatment and excellent adhesive property.

The ethylene vinyl alcohol polymer exhibits various properties depending on the content ratio of each component. When the content of ethylene is increased, the melting temperature and softening point are lowered, thereby improving the workability in film production and also increasing the humidity. On the other hand, when the content of vinyl alcohol is increased, gas (oxygen) barrier property is greatly improved.

Therefore, in order to overcome the recycling and complicated process problems due to the multilayer film structure of the ethylene vinyl alcohol polymer as described above, research and development of a new concept of a high barrier uni-material is required.

It is an object of the present invention to provide a graphite which is thermally and chemically treated with natural graphite to produce peeled graphite, which is used as a filler to modify the surface of the polymer to be hydrophobic so as to prevent moisture and gas from entering into the polymer matrix, To increase the barrier property and to extend the shelf life of food packaging, to develop materials applicable to pharmaceuticals, medical equipment, and electrical and electronic product packaging.

In order to achieve the above object, the present invention provides a composition having moisture and gas barrier properties, including a polymer and exfoliated graphite.

Preferably, the polymer is an ethylene vinyl alcohol polymer.

The weight ratio of the polymer to the peeled graphite is preferably 1: 0.001 to 1: 0.02.

The composition according to the present invention comprises a nonionic surfactant (Triton X-100), an anionic surfactant (SDS (sodium dodecylsulfate)), a graft polymer of an olefinic group and a maleic anhydride group (FUSABOND, POLYBOND) May further include one or more selected from the group.

In another aspect of the present invention, the present invention provides a film coated with a composition having the moisture and gas barrier properties.

In another aspect of the present invention, the present invention provides a process for producing graphite, comprising: a) heat treating graphite to produce expanded graphite; b) crushing the expanded graphite in a solvent selected from the group consisting of ethanol, distilled water, dimethylfuran, and dimethylsulfoxide, separating the solvent by centrifugation, and drying the separated graphite to produce peeled graphite; And c) mixing the polymer and the exfoliated graphite in a solvent selected from the group consisting of dimethylfuran or dimethylsulfoxide, stirring the solution, coating the solution on a glass plate followed by drying, or drying the polymer and the peeled graphite together and extruding And forming a film containing the polymer and the peeled graphite. The present invention also provides a method for producing a film having moisture and gas barrier properties.

In the film production method, the polymer is preferably an ethylene vinyl alcohol polymer, and the weight ratio of the polymer and the peeled graphite is preferably 1: 0.001 to 1: 0.02.

In the above film production method, the heat treatment in step a) is performed in an electron furnace at a temperature of 500 to 1100 占 폚 for 10 seconds to 60 minutes, or in a microwave for 10 seconds to 15 minutes do.

In the above film production method, the heat treatment in step a) may be performed in an electron furnace at a temperature of 500 to 1100 캜 for 30 seconds to 60 minutes, or in a microwave for 1 minute to 30 seconds to 15 minutes Lt; / RTI >

In the above film production method, the crushing of step b) is preferably performed with an ultrasonic crusher for 30 minutes to 24 hours, more specifically, for 8 hours to 16 hours, and centrifugation is performed at 1000 to 5000 RPM It is preferred to treat for 10 to 30 minutes, more specifically 2000 to 4000 RPM for 10 to 30 minutes. In addition, drying of step b) is suitably performed by raising the temperature to 130 to 160 ° C and then drying for 10 to 14 hours while lowering the temperature to 80 to 120 ° C.

In step c), a nonionic surfactant (Triton X-100), an anionic surfactant (SDS (sodium dodecyl sulfate)), an olefinic and a maleic anhydride (FUSABOND, POLYBOND) By weight of a graft polymer.

The composition comprising the polymer and the exfoliated graphite according to the present invention and the film applied thereon exhibit excellent moisture and gas barrier properties. Therefore, it can be effectively used for packaging foods, medicines, medical instruments, and electric and electronic products, which need to shut off the influx of moisture and gas.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a schematic structure in which a composition including a polymer and peeled graphite and a film coated thereon has moisture and gas barrier properties.
2 is a graph showing moisture permeation characteristics of an ethylene vinyl alcohol polymer film depending on the content of the peeled graphite.
3 is a graph showing changes in surface contact angle of an ethylene vinyl alcohol polymer film including peeled graphite relative to a pure ethylene vinyl alcohol polymer film according to the content of peeled graphite and the change with time.
4 is a graph showing gas barrier properties of an ethylene vinyl alcohol polymer film including peeled graphite relative to a pure ethylene vinyl alcohol polymer film according to the content of peeled graphite and relative humidity.

In general, in order to improve physical properties such as heat resistance, mechanical strength and permeability of the polymer, the filler has a physical and chemical interaction between the filler and the polymer, 1) the aspect ratio of the filler, 2) Dispersion, 3) the alignment and orientation of the filler and its major components, affecting the properties of the polymer film.

Research on the improvement of physical properties based on graphite, that is, graphite, which is chemically very stable substance among various functional fillers, has received much attention recently. Graphite is a hexagonal structure in which six carbon rings are connected to form a layer. The c-layer distance (c value) is 0.335 nm, and the layers are separated from each other.

Exfoliated graphite (EFG) obtained by separating the interlayer structure of graphite through chemical exfoliation has excellent thermal, mechanical and electrical properties and also has hydroxyl group (hydroxyl group, OH) is broken and has a hydrophobic property. As a result, the surface area capable of interacting with the polymer is widened, and the physical properties such as moisture and gas barrier properties can be expected to be improved.

In view of this, the present inventors modified the ethylene vinyl alcohol polymer surface to a peeled graphite filler having a hydrophobic functional group to increase the contact angle, thereby delaying the introduction of water and gas into the polymer matrix and improving the barrier property In addition, even if water or gas is introduced, the layer structure of the peeled graphite increases the barrier property by complicating the movement path of moisture and gas in the matrix, and it has been found that the shelf life of food packaging is extended, And electric and electronic product packaging.

The present invention provides a composition having moisture and gas barrier properties, including a polymer and exfoliated graphite.

In one embodiment of the present invention, the polymer may be an ethylene vinyl alcohol polymer.

In one embodiment according to the present invention, the weight ratio of polymer: peeled graphite may be from 1: 0.001 to 1: 0.02.

In one embodiment according to the present invention, the composition may contain at least one of a nonionic surfactant (Triton X-100), an anionic surfactant (SDS (sodium dodecylsulfate)), an olefinic and a maleic anhydride (FUSABOND, POLYBOND) A graft polymer, and a graft polymer.

In another aspect according to the present invention, the present invention provides a film coated with a composition.

In another aspect of the present invention, the present invention provides a method for producing graphite, comprising: a) heat treating graphite to produce expanded graphite; b) crushing the expanded graphite in a solvent selected from the group consisting of ethanol, distilled water, dimethylfuran, and dimethylsulfoxide, separating the solvent by centrifugation, and drying the separated graphite to produce peeled graphite; And c) mixing the polymer and the exfoliated graphite in a solvent selected from the group consisting of dimethylfuran and dimethylsulfoxide, stirring the solution, coating the solution on a glass plate followed by drying, or drying the polymer and the exfoliated graphite together and extruding And forming a film containing the polymer and the peeled graphite. The present invention also provides a method for producing a film having moisture and gas barrier properties.

In one embodiment of the present invention, the polymer may be an ethylene vinyl alcohol polymer.

In one embodiment of the present invention, the weight ratio of the polymer: peeled graphite may be from 1: 0.001 to 1: 0.02.

In one embodiment according to the present invention, the heat treatment in step a) is carried out in an electron furnace at a temperature of 500 to 1100 占 폚 for 10 seconds to 60 minutes, or in a microwave for 10 seconds to 15 minutes Wherein the film has moisture and gas barrier properties.

In the above film production method, the heat treatment in step a) may be performed in an electron furnace at a temperature of 500 to 1100 캜 for 30 seconds to 60 minutes, or in a microwave for 1 minute to 30 seconds to 15 minutes Lt; / RTI >

In one embodiment of the present invention, the crushing of step b) is for 30 minutes to 24 hours with an ultrasonic crusher, more specifically from 8 hours to 16 hours, centrifugation is carried out at 1000 to 5000 RPM at 10 To 30 minutes, more specifically from 2000 to 4000 RPM for 10 to 30 minutes. Wherein the drying is carried out at 130 to 160 ° C. and then the drying is carried out for 10 to 14 hours while the temperature is lowered to 80 to 120 ° C. The present invention also provides a method for producing a film having moisture and gas barrier properties.

(Triton X-100), an anionic surfactant (SDS (sodium dodecyl sulfate)), an olefin-based and a maleic anhydride-based (FUSABOND, POLYBOND) surfactant as a surfactant in step c) By weight of a graft polymer.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, it is intended to assist the understanding of the invention and is not intended to limit the scope of the invention.

Example 1. Preparation of exfoliated graphite

1. Expandable graphite is placed in a quartz crucible and heat treated in a furnace at a temperature of 500 to 1100 ° C for 30 seconds to 60 minutes or in a microwave for 1 minute and 30 seconds to 15 minutes Lt; RTI ID = 0.0 > expanded graphite. ≪ / RTI > Expanded graphite is produced by intermolecular compounds in graphite that generate strong molecular motion and high pressure at high temperatures, thereby breaking Van der Waals bonds.

2. The resulting expanded graphite was treated for 12 hours with ethanol (or distilled water, DMF, DMSO) and an ultrasonic shredder (ultrasonic cleaner, homogenizer) and centrifuged at 3000 RPM for 20 minutes Lt; / RTI > The graphite peeled off by ultrasonic waves was placed in a drier, heated to 130 to 160 ° C, and dried for 12 hours while gradually lowering the temperature to 120 ° C.

Example 2. Preparation of ethylene vinyl alcohol polymer / exfoliated graphite single uni-material

The process for producing an ethylene vinyl alcohol polymer / peeled graphite composite film is as follows.

1) Solvent system

① When dimethylfuran (DMF) was used as a solvent

The ethylene vinyl alcohol polymer and the peeled graphite were put into dimethyl furan (DMF) and then stirred with an ultrasonic shredder (ultrasonic washing machine) for 1 hour. The composition of each mixing ratio is shown in Table 1. In order to coat the mixed solution, the mixed solution was placed on a glass plate, and a bar applicator was placed on one end of the glass plate and then coated to a constant thickness using a bar coater. To dry the film, the coated glass plate was placed in a dryer and then dried at 120 DEG C for 12 hours. The dried ethylene vinyl alcohol polymer and the peeled graphite composite film were removed from the glass plate. Triton X-100, SDS (sodium dodecylsulfate), FUSABOND, POLYBOND and the like were added as a surfactant to improve the dispersibility during the above process.

② When dimethylsulfoxide (DMSO) was used as a solvent

The ethylene vinyl alcohol polymer and the peeled graphite were put into a vial, and then DMSO solvent was added thereto, followed by stirring for 2 hours using an ultrasonic wave shaker (ultrasonic washing machine). The agitated mixture was applied to a glass plate using a bar coater and then dried at 60 DEG C for 4 hours. (Final thickness: 25 탆)

After the film was washed with distilled water to remove the DMSO solvent, the film was dried at 45 ° C for 2 hours and then the film was peeled from the glass plate to prepare an ethylene vinyl alcohol polymer and a peeled graphite composite film. Triton X-100, SDS (sodium dodecylsulfate), FUSABOND, POLYBOND and the like were added as a surfactant to improve the dispersibility during the above process.

2) Extrusion system

① Ethylene vinyl alcohol polymer and exfoliated graphite Prior to the extrusion process of a single uni-material, the ethylene vinyl alcohol polymer and the appropriate amount of exfoliated graphite powder were put in a plastic pouch to remove water, and then dried in a dryer at 105 ° C for 12 Hour, and the content ratio thereof is shown in Table 1. A 3 to 20% ethylene vinyl alcohol polymer and a peeled graphite master batch were prepared using a BA-19 twin screw extruder system manufactured by Bautech Co., Ltd. for the preparation of composite films. The prepared masterbatch was used to prepare an ethylene vinyl alcohol polymer and peeled graphite single uni-material. The barrel pressure of the twin screw extrusion system was 4.9 kgf / cm ² and the temperature was 180 ° C headers, Zone 1 to 6 (metering and compression zone) 180 ° C and Zone 7 ) ≪ / RTI > Ethylene vinyl alcohol polymer and peeled graphite composite film were prepared with a thickness of 70 ± 2 μm. The thickness of the film was confirmed by a Digimatic Micrometer of Mituyo.

② Triton X-100, SDS (sodium dodecylsulfate), FUSABOND, POLYBOND and the like were added as a surfactant to improve dispersibility during the above process.

Sample code EVOH (g) DMSO (g) EFG (g) Total (g) Pure EVOH 3.600 16.400 0.000 20,000 EVOH / EFG 0.1% 3.600 16.400 0.004 20.004 EVOH / EFG 0.3% 3.600 16.400 0.011 20.011 EVOH / EFG 0.5% 3.600 16.400 0.018 20.018 EVOH / EFG 1.0% 3.600 16.400 0.036 20.036 EVOH / EFG 2.0% 3.600 16.400 0.072 20.072

Experimental Example  1. Moisture interception characteristics <current level 1/5 reduction>

To analyze the moisture barrier properties of the ethylene vinyl alcohol polymer, a WVTR (8001 Water Vapor Permeation Analyzer, Illinois Instruments Co., USA, g / m ² / day, relative humidity (RH) 85%) was used according to ASTM F-1249 In order to analyze the surface properties of the ethylene vinyl alcohol polymer and the peeled graphite composite film, the contact angle (25 mm x 25 mm) with time was measured according to ASTM D 570-98 (30, 95%, 24 hours) Phoenix 300-Touch, SEO Co., Korea). The results are shown in FIG. 2 and FIG. 3, respectively.

The water permeability of the pure ethylene vinyl alcohol polymer was 7.8 g / m ² / day, but decreased to 1.5 g / m ² / day as the amount of peeled graphite increased. In the case of moisture absorption, pure ethylene vinyl It was confirmed that the alcohol polymer absorbed 9.4% of water and decreased to 5.6% as the amount of peeled graphite increased.

As shown in FIG. 3, the initial contact angle increases with the amount of peeled graphite, and the amount of change in contact angle with time changes. This shows that the peeled graphite having hydrophobic properties is arranged on the surface to provide water-contact resistance to the ethylene vinyl alcohol polymer, thereby increasing the barrier against moisture.

Experimental Example  2. Gas shutoff characteristics

To determine whether the oxygen permeability of the ethylene vinyl alcohol polymer under the high temperature and high humidity conditions was 5.0 cc / m ² / day or less, the oxygen permeability was measured according to ASTM D-3985 by varying the humidity conditions (0%, 40%, 60% (7001 oxygen Permeation Analyzer, Illinois Instruments Co., USA, cc / m 2 / day) were measured, and as a result, if the EVOH-EFG 2.0% relative humidity (RH) 80%, an oxygen permeability 2.42cc / m ² / day. This is shown in FIG.

It was confirmed that the oxygen permeability was decreased according to the peeled graphite content. This is because the peeled graphite dispersed in the ethylene vinyl alcohol polymer matrix increases the hydrophobicity and increases the complexity of the gas flow path into the film.

It was found that under high humidity, the amount of change in oxygen permeability also decreased as the content of peeled graphite increased.

Further, as the content of the peeled graphite is increased, the influence of the moisture on the film is reduced, and as a result, the ethylene vinyl alcohol polymer and the peeled graphite composite film under higher humidity than the oxygen permeability of the pure ethylene vinyl alcohol polymer under the drying condition The oxygen permeability is lowered.

Claims (18)

A composition having moisture and gas barrier properties, including a polymer and exfoliated graphite.
The method according to claim 1,
Wherein the polymer is an ethylene vinyl alcohol polymer.
The method according to claim 1,
Wherein the weight ratio of polymer: peeled graphite is from 1: 0.001 to 1: 0.02.
The method according to claim 1,
The composition is selected from the group consisting of a nonionic surfactant (Triton X-100), an anionic surfactant (SDS (sodium dodecylsulfate)) as a surfactant, and a graft polymer of olefinic and maleic anhydride (FUSABOND, POLYBOND) &Lt; / RTI &gt; wherein the composition further comprises one or more of the following ingredients.
A film coated with the composition of any one of claims 1 to 4.
6. The method of claim 5,
Wherein the film is for at least one packaging selected from the group consisting of food packaging, pharmaceutical packaging, medical machine packaging, and packaging of electrical and electronic products.
a) heat treating the graphite to produce expanded graphite;
b) crushing the expanded graphite in a solvent selected from the group consisting of ethanol, distilled water, dimethylfuran, and dimethylsulfoxide, separating the solvent by centrifugation, and drying the separated graphite to produce peeled graphite; And
c) The polymer and the exfoliated graphite are placed in a solvent selected from the group consisting of dimethylfuran and dimethylsulfoxide, stirred, coated on a glass plate and dried, or the polymer and the exfoliated graphite are dried together and extruded, And forming a film containing the peeled graphite.
A method for producing a film having moisture and gas barrier properties.
8. The method of claim 7,
Wherein the polymer is an ethylene vinyl alcohol polymer. 2. The film according to claim 1, wherein the polymer is an ethylene vinyl alcohol polymer.
8. The method of claim 7,
Wherein the weight ratio of polymer: peeled graphite is 1: 0.001 to 1: 0.02.
8. The method of claim 7,
Wherein the heat treatment in the step a) is a heat treatment in an electron furnace at a temperature of 500 to 1100 ° C for 10 seconds to 60 minutes or a heat treatment in a microwave for 10 seconds to 15 minutes. A method for producing a film having gas barrier properties.
8. The method of claim 7,
Wherein the heat treatment in step a) is performed in an electron furnace at a temperature of 500 to 1100 占 폚 for 30 seconds to 60 minutes or in a microwave for 1 minute and 30 seconds to 15 minutes. A method for producing a film having moisture and gas barrier properties.
8. The method of claim 7,
Characterized in that the crushing of step b) is carried out with an ultrasonic crusher for 30 minutes to 24 hours.
8. The method of claim 7,
Characterized in that the crushing of step b) is carried out with an ultrasonic crusher for 8 to 16 hours.
8. The method of claim 7,
Wherein the centrifugal separation in step b) is performed at 1000 to 5000 RPM for 10 to 30 minutes.
8. The method of claim 7,
Wherein the centrifugal separation in step b) is performed at 2000 to 4000 RPM for 10 to 30 minutes.
8. The method of claim 7,
Wherein the drying of step b) is carried out by raising the temperature to 130 to 160 ° C, and then drying the film for 10 to 14 hours while lowering the temperature to 80 to 120 ° C.
8. The method of claim 7,
(Triton X-100), an anionic surfactant (SDS (sodium dodecylsulfate)), and an olefin-based and a maleic anhydride-based (FUSABOND, POLYBOND) graft polymer as the surfactant in the step c) Wherein at least one selected from the group consisting of water and gas barrier properties is further added.
18. A film having moisture and gas barrier properties, produced by the method of any one of claims 7 to 17.

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