KR20100122637A - Method for preparing an organically modified layered clay using a supercritical fluid state of carbon dioxide - Google Patents

Abstract

PURPOSE: A manufacturing method of organically modified layered clay is provided to easily manufacture the organically modified layered clay for manufacturing a polymer-clay nanocomposite by improving the compatibility with a polymer. CONSTITUTION: A manufacturing method of organically modified layered clay comprises the following steps: adding carbon dioxide and layered clay to a solution dissolved with an organic polymer or an oligomer, and dispersing the added material; adsorbing the organic polymer or the oligomer to the surface of the clay, by swelling the clay through changing the carbon dioxide into a supercritical fluid state; and interlayer exfoliating the clay by vaporizing the carbon dioxide.

Description

Manufacturing method of organic layered clay using carbon dioxide in supercritical fluid state {METHOD FOR PREPARING AN ORGANICALLY MODIFIED LAYERED CLAY USING A SUPERCRITICAL FLUID STATE OF CARBON DIOXIDE}

The present invention relates to a method for producing an organic layered clay which is usefully used for the preparation of polymer-clay nanocomposites using carbon dioxide in a supercritical fluid state.

Nanomaterial refers to a material consisting of a unit structure of ultra-fine size, the size of the unit structure is within 100nm, which corresponds to less than one thousandth of the hair thickness. This is a new and versatile advanced technology compared to conventional micrometer-sized materials, and is an advanced new material that meets the fine parts and versatility required by modern industrial technology.

Inorganic / metal particle-dispersed polymer nanocomposite (nanocomposite) has improved mechanical properties, ie impact resistance, toughness and transparency by peeling and dispersing inorganic / metal particles at a nano-scale in polymer materials such as thermoplastic resins, thermosetting resins, etc. It is a new concept of next generation composite material with much improved ① strength and stiffness, ② gas and liquid permeation inhibitory performance, ③ flame retardancy and flame resistance, ④ abrasion resistance, ⑤ high temperature stability. Based on these characteristics, inorganic / metal particle-dispersed polymer nanocomposites are expected to be applied to society, such as automobiles, aerospace and ships, packaging materials and containers, paints and coatings, electronic information, civil engineering, and medical fields.

The polymer-clay nanocomposites have recently emerged as part of increasing weight reduction and recyclability while maintaining excellent physical properties of the inorganic / metal particle-dispersed polymer nanocomposites. The polymer-clay nanocomposite manufacturing technology induces delamination of a layered structure by infiltrating a polymer resin between layers of clay having a silicate layered structure, and peels and disperses nanoscale layered silicate in a polymer resin, thereby making it a general purpose that the mechanical properties are poor. It is a technology that can improve the physical properties of polymers. Such polymer-clay nanocomposites are broadly classified into intercalated nanocomposites that insert polymers between silicate layers and exfoliated nanocomposites that completely disperse the silicate layers.

The layered silicate constituting the layered clay is basically composed of a combination of silica tetrahedral sheet and alumina octahedral sheet, and the layers are filled with ions such as Na ⁺ , Li ⁺ , At the end of the sheet is an OH group. That is, the layered clay has a very polar hydrophilic structure.

However, due to the strong hydrophilicity of the layered clays as described above, due to the presence of strong attractive forces between the layers of the clay and the layers, the polymer-clay nanocomposites were made to incorporate most of the lipophilic polymer into the layer of the layered clay. There was a problem that it is very difficult to peel and disperse the layered silicate in the polymer resin.

For example, in the case of montmorillonite (MMT), a formula [(Al _3.15 Mg _0.85 ) Si ₈ O ₂₀ (OH) ₄ X _0.85 nH ₂ O], which is a kind of clay having a silicate layered structure, The lower valence Al ³⁺ ions are substituted for Si ⁴⁺ in the tetrahedral silica layer, and the lower valence Fe ²⁺ and Mg ²⁺ ions are substituted for Al ³⁺ in the octahedral alumina layer so that the total layer charge is negative. -) And cations exist between layers to compensate for this. Most cations present between layers are Ca ²⁺ and Mg ²⁺ ions, and Na ⁺ , H ⁺ , K ^+, etc., are present in small amounts. The divalent cations have a stronger bond with the tetrahedral silicate layer than the monovalent cations. It is small and consequently exhibits a low degree of swelling upon contact with water. The structure of a typical montmorillonite is shown as a schematic diagram in FIG.

Therefore, in order to remedy this problem, a technique for preparing an organically modified layered clay (OLS) by introducing a low molecular weight intercalant between the layered structures of the polar silicates has been introduced. The organic layered clay has excellent compatibility with polymers such as the cations present between the silicate layers are replaced by cations of organic agents, thereby improving the surface and facilitating the penetration of polymers in the preparation of clay-polymer nanocomposites. Has the advantage.

Accordingly, efforts to more easily manufacture organic layered clay having increased compatibility with polymers have been continuously studied.

Accordingly, an object of the present invention is to provide a method for more easily preparing an organic layered clay that can be usefully used in preparing a polymer-clay nanocomposite due to increased compatibility with a polymer.

The present invention to achieve the above object,

(1) After dispersing by adding carbon dioxide and layered clay to a solution in which an organic polymer or oligomer is dissolved,

(2) adsorbing the organic polymer or oligomer to the surface of the clay by making the carbon dioxide into a supercritical fluid state and swelling the clay,

(3) vaporizing the carbon dioxide in the supercritical fluid state to delaminate the clay,

It provides a method for producing an organic layered clay.

According to the manufacturing method of the present invention, the compatibility with the polymer is increased, so that the organic layered clay which can be usefully used in the preparation of the polymer-clay nanocomposite can be produced more easily, and the organic layered clay of the present invention thus prepared is It is possible to provide a polymer-clay nanocomposite excellent in strength, stiffness, gas permeability, flame resistance, abrasion resistance and high temperature stability without damaging the impact resistance, toughness and transparency of the polymer resin.

The organic layered clay manufacturing method according to the present invention comprises the steps of: (1) dissolving an organic polymer or oligomer in a solvent and then dispersing by adding carbon dioxide and layered clay to the solution; (2) adsorbing an organic polymer or oligomer to the surface of the clay by swelling the clay by making the carbon dioxide into a supercritical fluid state; And (3) delaminating the clay using an expanding force at the moment of vaporizing and vaporizing carbon dioxide in the supercritical fluid state. In the present invention, even after the carbon dioxide is vaporized, the organic polymer or oligomer is adsorbed on the surface of the clay, thereby maintaining the peeled state of the clay.

According to the present invention, prior to the step (1), the ultrasonic wave in the state of dispersing the layered clay in distilled water (H ₂ O), sonicator (sonicator) for the layered clay, or dispersed in the distilled water By carrying out the treatment, the layered clay can be preliminarily dispersed and swelled.

The particles of clay are formed by layers or stacks of small plates of crystalline silicates. The layers are tightly bound by electrochemical attraction, when they are exposed to distilled water, the distilled water diffuses into the particles between the layers and separates the layers so that the layers do not bind strongly. That is, the clay has the property of swelling by adding distilled water. In addition, ultrasonic treatment may be used as one of the physical peeling methods, and as the treatment time of the ultrasonic wave becomes longer, it may be confirmed that the size of the layered clay having a non-uniform size is reduced while peeling.

In step (1) of the process of the invention, the organic polymer or oligomer is dissolved in a solvent and then dispersed by adding carbon dioxide and layered clay to this solution.

The layered clay is montmorillonite (MTMT), bentonite, kaolinite, kaolinite, mica, hectorite, fluorohectorite, saponite, saponite, vadel Beidelite, nontronite, stevensite, vermiculite, halosite, volkonskoite, suconite, sugite, magadite, kenya Kenyalite and mixtures thereof may be selected, and montmorillonite may be preferably used.

Montmorillonite is a representative 2: 1 smectite based layered mineral with a high aspect ratio (500 to 1000). In general, the montmorillonite has an interlayer distance of less than 1 nm, but the interlayer distance varies depending on the type of cation and water content. In the natural state where the plated Na ⁺ montmorillonite is aggregated, Na ⁺ or Ca ²⁺ is present between the layers with moisture, and the distance between layers is about 1 nm or less.

The organic polymer or oligomer is in the group consisting of ethylene vinyl acetate (EVA), ethylene-propylene diene rubber (EPDM), thermoplastic olefin (TPO), maleic anhydride grafted polypropylene (PP-g-MA) and mixtures thereof Can be selected.

The solvent of the solution in which the organic polymer or oligomer is dissolved is methanol, ethanol, isopropyl alcohol, methyl formamide, dimethyl sulfoxide, dimethyl acetamide, xylene, toluene, benzene, acetone, dichloromethane and mixtures thereof. It may be selected from, preferably toluene can be used.

Based on 100 parts by weight of the layered clay, the carbon dioxide may be used in an amount of preferably 30 to 100 parts by weight, more preferably 50 to 60 parts by weight, and preferably 80 to 200 parts by weight of the organic polymer or oligomer. More preferably 90 to 110 parts by weight.

In step (2) of the method of the present invention, the organic polymer or oligomer is adsorbed on the surface of the clay by swelling the clay by making carbon dioxide into a supercritical fluid state.

Supercritical fluid (SCF) refers to a fluid at a time when liquid and gas cannot be distinguished by reaching a state beyond the limits of constant high temperature and high pressure. The density of the molecule is close to liquid, but the viscosity is low, and thus close to gas. In addition, it has fast thermal diffusion and is useful for chemical reaction.

As shown in FIG. 2, water or carbon dioxide exists in a gas, a liquid, and a solid phase at pressure and temperature conditions below a critical point, and each curve means pressure or temperature conditions in which two phases are in equilibrium. In other words, the curve between liquid and gas means the boiling point under each pressure condition, and increasing the temperature or pressure along this line will reach the critical point. As the temperature or pressure increases, the liquid phase decreases in density due to thermal expansion, and the gas phase continues in opposing changes where the density increases with increasing pressure. Has the same value and there is no distinction between the two phases. This state is called a supercritical state, and since it is easy to deform and has the characteristics of a free flowing fluid, unlike a solid, it is called a supercritical fluid (SCF). For reference, the critical point of water is 221 bar, 374 ° C, and the critical point of carbon dioxide is 73.8 bar, 31.1 ° C.

Supercritical fluid carbon dioxide has a low threshold (73.8 bar, 31.1 ° C) unlike other supercritical fluids. In addition, carbon dioxide in the supercritical fluid state can not only easily control the dissolving power by adjusting the temperature and pressure, but also has a diffusion coefficient of about 10-100 times lower than that of the general organic solvent and water and has no surface tension.

In the present invention, a conventional supercritical fluid apparatus (autoclave function) can be used to make carbon dioxide into a supercritical fluid state, and a schematic diagram and photograph of a conventional supercritical fluid apparatus are shown in FIG. 3.

In step (3) of the method of the present invention, the delamination of the clay is accelerated using the expanding force at the moment of vaporizing and vaporizing carbon dioxide in a supercritical fluid state.

The vaporization of carbon dioxide in the supercritical fluid state can also be achieved by increasing the pressure and / or temperature in a supercritical fluid device having an autoclave function.

An example of the organic treatment of layered clay according to one embodiment of such a method of the present invention is shown as a schematic diagram in FIG. 4.

The organic layered clay obtained by the organic treatment by the method of the present invention maintains the delamination state due to the presence of the organic polymer or oligomer adsorbed on the surface, thereby exhibiting excellent polymer compatibility in the preparation of the polymer-clay nanocomposite in the future. Can be. In addition, the organic layered clay of the present invention can provide a polymer-clay nanocomposite excellent in strength, stiffness, gas permeability, flame resistance, abrasion resistance and high temperature stability without damaging the impact resistance, toughness and transparency of the polymer resin.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1

After dissolving ethylene-propylene diene rubber (EPDM) in toluene, montmorillonite Na ^{+ ®} (Nanoco Co., Ltd.) was added to the solution and introduced into a supercritical fluid device (ILSIN Autoclave). Under pressure and temperature conditions of 110 ° C, carbon dioxide is made into a supercritical fluid state, swelling montmorillonite to adsorb EPDM on the surface, and then vaporizing the supercritical fluid carbon dioxide under atmospheric pressure and temperature conditions of 110 ° C. The organic treatment of montmorillonite was carried out by delaminating the lilonite. At this time, carbon dioxide and EPDM were used in amounts of 60 parts by weight and 100 parts by weight, respectively, based on 100 parts by weight of montmorillonite.

As a result of X-ray diffraction (XRD) analysis of the obtained product, it was confirmed that the organic treatment was effectively performed, and the results are shown in Table 1 below.

[Example 2]

Before adding montmorillonite to the ethylene-propylene diene rubber (EPDM) solution, montmorillonite was dispersed in secondary distilled water (H ₂ O) by the same method as in Example 1 above. The organic treatment of montmorillonite was performed.

As a result of XRD analysis of the obtained product, it can be confirmed that the organic treatment was effectively performed, and the results are shown in Table 1 below.

Comparative Example 1

The organic treatment of montmorillonite was carried out in the same manner as in Example 1, except that EPDM and montmorillonite were simply mixed without toluene and then the mixture was introduced into a supercritical fluid apparatus. .

As a result of XRD analysis of the obtained product, it was confirmed that EPDM was not dissolved and the organication treatment was insufficient, and the results are shown in Table 1 below.

Comparative Example 2

The montmorillonite organic treatment was performed in the same manner as in Comparative Example 1 except that montmorillonite was dispersed in secondary distilled water without using EPDM.

As a result of XRD analysis of the obtained product, it was confirmed that no organic treatment was performed, and the results are shown in Table 1 below.

division 2θ d (Å) Example 1 7.26 12.17 Example 2 7.82 11.30 Comparative Example 1 8.24 10.72 Comparative Example 2 8.02 11.02

"D value" shown in Table 1 indicates the interval between clays, which means that the larger the d value, the more dispersed the nanocomposite is in the nanocomposite, and the nanocomposite dispersed in the exfoliated state Since d shows a high physical property improvement with a small amount of clay, this d value is an important measure of physical property judgment.

Therefore, from the results of Table 1, it can be seen that the products obtained in Examples 1 and 2 are effectively organicized and dispersed in a well-peeled state.

1 is a schematic view showing the structure of a typical montmorillonite,

2 is a phase diagram of carbon dioxide according to pressure and temperature changes,

3 is a schematic and photograph of a conventional supercritical fluid apparatus,

4 is a schematic view showing an example of the organic treatment of layered clay according to one embodiment of the method of the present invention.

Claims (8)

(1) After dispersing by adding carbon dioxide and layered clay to a solution in which an organic polymer or oligomer is dissolved, (2) adsorbing the organic polymer or oligomer to the surface of the clay by making the carbon dioxide into a supercritical fluid state and swelling the clay, (3) vaporizing the carbon dioxide in the supercritical fluid state to delaminate the clay, Process for producing organic layered clay. The method of claim 1, Prior to step (1), the layered clay is dispersed in distilled water (H ₂ O), sonicated (sonicator) treatment for the layered clay, or the ultrasonic treatment is performed while the layered clay is dispersed in distilled water A method for producing an organic layered clay, characterized in that the. The method of claim 1, The layered clay is montmorillonite (MMT), bentonite, bentonite, kalinite, mica, hectorite, fluorohectorite, saponite, saponite, vadel Beidelite, nontronite, stevensite, vermiculite, halosite, volkonskoite, suconite, sugite, magadite, kenya A method for producing an organic layered clay, characterized in that selected from the group consisting of kenyalite and mixtures thereof. The method of claim 1, The organic polymer or oligomer in the group consisting of ethylene vinyl acetate (EVA), ethylene-propylene diene rubber (EPDM), thermoplastic olefin (TPO), maleic anhydride grafted polypropylene (PP-g-MA) and mixtures thereof The method for producing an organic layered clay, characterized in that selected. The method of claim 1, The solution in which the organic polymer or oligomer is dissolved is selected from the group consisting of methanol, ethanol, isopropyl alcohol, methylformamide, dimethyl sulfoxide, dimethylacetamide, xylene, toluene, benzene, acetone, dichloromethane and mixtures thereof. A method for producing an organic layered clay, characterized in that it comprises a solvent selected. The method of claim 1, The carbon dioxide and the organic polymer or oligomer are used in an amount of 30 to 100 parts by weight and 80 to 200 parts by weight based on 100 parts by weight of the layered clay, respectively. An organic layered clay obtained by adsorbing an organic polymer or oligomer on a surface prepared by the method according to any one of claims 1 to 6. A polymer-clay nanocomposite obtained by mixing the organic layered clay of claim 7 and a polymer material.

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