KR20190061458A - Method for dispersing nanoclay using a binary system - Google Patents

Abstract

The present invention relates to a manufacturing method of a polyolefin-organic clay hybrid nanocomposite comprising: a step 1 of preparing a mixture of polyolefin, organic layered structure clay and a hollow glass microsphere; and a step 2 of putting the mixture into a melting extruder, extruding the mixture by applying shear stress to the same, dispersing the organic layered structure clay by a ball milling behavior of the hollow glass microsphere and inserting the organic layered structure clay between polyolefin chains. In addition, the present invention relates to a nanocomposite manufactured by the method and a barrier film manufactured thereby. According to the present invention, it is possible to manufacture a nanocomposite of which the weight is reduced by using the hollow glass microsphere, and which is high in terms of a dispersion of organic clay, increases distances between layers of layered organic clay, improves mechanical properties such as tensile stress, tensile strength and elongation and a thermal stability, and has a gas barrier property.

Description

[0001] The present invention relates to a nanoclay dispersion method using a binary system,

The present invention relates to a nano-clay dispersion method using a two-component system, and more particularly, to a gas-impermeable polyolefin-organic clay nanocomposite using a nanoclay dispersion method using a two-component system, a method for producing the same, Lt; / RTI >

Over the past decade, the development of polymer-layer silicate (clay) nanocomposites has been actively pursued with superior properties improvements over homopolymers. The polymer-clay nanocomposite can improve the mechanical properties by enhancing the tensile strength and toughness by promoting the transfer of stress to the strengthening phase of the bond between the clay and the polymer matrix having a large surface area, and the permeability of the permeant material produced by the impermeable clay layer The barrier property can be improved and the barrier film can be used for manufacturing the barrier film.

Barrier film is a film that usually protects the life and performance of a product by cutting off oxygen and moisture. Recently, the barrier film has been used as an encapsulating film, a back sheet, a high vacuum insulation material for construction, an industrial packaging material, a flexible display substrate, Film and so on. However, in the case of polymer materials with a wide range of demands, oxygen and moisture shielding characteristics do not satisfy the required level. Therefore, in order to overcome this, a variety of metal thin films, polymers and nano- .

Polyvinyl alcohol (PVA) films or EVOH films or PVDC films, which are copolymers of ethylene and vinyl alcohol, are currently used as gas barrier materials, but compared to such pure polymer films When a nano clay such as montmorillonite is used as a filler to produce a polymer nanocomposite and used as a gas barrier material, a clay layer having gas barrier properties The permeation path of the gas becomes longer, and the gas barrier property is further improved as compared with the pure polymer material. The key to enhancing gas barrier properties is to control the gas permeation pathway. For this purpose, it is possible to use a method of adding a large amount of nano-clay minerals having an excellent aspect ratio or adding a nano-clay mineral having a small specific surface area to a thinner nano-clay mineral having a large specific surface area. However, it is not easy to maintain the dispersibility in the polymer by controlling the number of layers of nano-clay minerals.

The process of preparing the polymer-clay nanocomposite can be summarized as a process of dispersing the layered clay into the polymer matrix. Techniques such as solution intercalation, intercalative polymerization, melt intercalation, and in situ direct synthesis have been used. However, since the layered nano-clay particles have a very large amount of ions and a functional group having polarity, they have a very high hydrophilicity, so that they are very difficult to be dispersed among polymers such as polyolefins, most of which are hydrophobic. .

For example, a method of grafting or incorporating a functionalized monomer such as a maleic anhydride or a hydroxyl group to increase the affinity between the clay and the polymer matrix, and adding a functional group to the main chain can be used . Alternatively, a method may be employed in which the inorganic clay is replaced with an organic onium ion to modify the natural clay to reduce the attraction between the clay layers and to improve the compatibility between the clay and the polymer matrix. However, this method has a problem that the continuity of processing is poor and the mechanical properties and barrier properties of the nanocomposite are not sufficiently improved.

An object of the present invention is to provide a polyolefin-organic clay hybrid nanocomposite which is improved in mechanical properties such as tensile stress, tensile strength and elongation, and barrier properties and can be used as a material of a gas barrier film and a method for producing the same.

Another object of the present invention is to provide a barrier film using the polyolefin-organic clay hybrid nanocomposite.

A first aspect of the present invention is a method for preparing a porous glass microsphere comprising the steps of: (1) preparing a mixture comprising a polyolefin, an organic layered clay and a hollow glass microsphere; And

(Step 2) of dispersing the organic layered clay by means of the ball milling action of the hollow glass microspheres and inserting the organic layered clay between the polyolefin chains by introducing the mixture into a melt extruder, applying shear stress and melt extrusion, Organic clay hybrid nanocomposite, which comprises a polyolefin-organic clay hybrid nanocomposite.

A second embodiment of the present invention is a polyolefin prepared according to the first aspect, An organic layered clay melted and inserted into the polyolefin chain; And hollow glass microspheres used to disperse the organic layered clay. The present invention also provides gas-impermeable polyolefin-organic clay hybrid nanocomposites.

A third aspect of the present invention provides a barrier film made from the polyolefin-organic clay hybrid nanocomposite of the second aspect.

A fourth aspect of the present invention provides a plastic substrate comprising the barrier film of the third aspect.

Hereinafter, the present invention will be described in detail.

Researches on synthetic foams in which hollow glass microspheres (HGM) are dispersed in a polymer matrix are actively being studied. Hollow glass microspheres (HGM) are inorganic fillers that are attracted to a variety of industries because of their advantages such as internal inert gas and external hard glass, low thermal conductivity and light weight. The inventors of the present invention studied a method of significantly improving mechanical properties and barrier properties such as tensile stress, tensile strength and elongation of a polyolefin-organic clay nanocomposite, and found that when a hollow glass microsphere is mixed with a polyolefin and an organic clay As a result of the melt extrusion, the dispersion degree of the organic clay in the polyolefin matrix and the interlayer distance of the layered organic clay were increased by the ball mill behavior of the hollow glass microspheres, thereby improving the mechanical properties such as tensile stress, tensile strength and elongation and thermal stability , It was confirmed that a nanocomposite having remarkably improved gas barrier properties can be produced. The present invention is based on this.

A nanocomposite is a nanometer-sized composite of a dispersed phase and a matrix. The nanocomposite is composed of two or more types of structures or materials and has a nanoscale (10 ^-9 m) phase size. it means. More specifically, in the present invention, a nanocomposite is formed by exfoliating a nano-sized layered clay compound in a matrix polymer such as an oligomer, a polymer, or a blend thereof, Refers to a complex in which an exfoliated nanocomposite, a tactoidal nanocomposite, or a mixture thereof is dispersed.

The present invention produces a polymer-organic clay nanocomposite using a melt insertion method. The conventional method has a problem that it is difficult to insert a polymer such as polyolefin between clay layers having a very high hydrophilicity due to existence of a very large amount of ion and a functional group having polarity. As a result, mechanical properties such as tensile stress, tensile strength and elongation Organic clay hybrid nanocomposite which can be used as a material of a gas barrier film. The method for producing a polyolefin-organic clay hybrid nanocomposite of the present invention comprises dispersing an organic layered clay by a ball milling action of a hollow glass microsphere by adding a hollow glass microsphere to a mixture of a polyolefin and an organic layered clay Characterized in that an organic layered clay is inserted between the polyolefin chains.

In the present invention, the polyolefin may be a polypropylene, a low density polyethylene, a high density polyethylene, a linear low density polyethylene, a copolymer of ethylene and a C3-C20 alpha olefin, or the like. Preferably, the polyolefin may be a polypropylene. The polypropylene may be a propylene homopolymer or a copolymer of propylene with up to 20 wt% of an alpha olefin, particularly preferably with up to 20 wt% Ethylene copolymer. In order to simultaneously improve the rigidity, heat resistance, and impact resistance of the nanocomposite, it is preferable to blend a general polypropylene homopolymer and a high-stiffness or highly crystalline propylene / alpha -olefin block copolymer.

The melt index of the polyolefin preferably ranges from 0.1 to 500 g / 10 min (230 DEG C, 2.16 kg), more preferably from 0.5 to 200 g / 10 min. When the melt index is less than 0.1 g / 10 min, the flowability is decreased and the moldability is deteriorated. When the melt index is more than 500 g / 10 min, the impact resistance is drastically decreased.

In the present invention, the polyolefin is preferably contained in an amount of 50 to 99 wt%, more preferably 80 to 95 wt%, based on the total weight of the mixture.

The weight average molecular weight of the polyolefin is preferably in the range of 5,000 to 5,000,000, more preferably in the range of 10,000 to 1,000,000. When the weight average molecular weight of the polyolefin is less than 5,000, the compatibility with the organic clay is insufficient to lower the physical properties. When the weight average molecular weight is more than 5,000,000, the processability and dispersibility of the nanocomposite deteriorate.

In the present invention, the hollow glass microspheres exhibit the behavior of the ball mill in the melt extrusion process, thereby dispersing the organic clay and extending the distance between the organic clay layers. The hollow glass microspheres applicable to the present invention can be prepared by techniques known in the art. Typically, a technique for making hollow glass microspheres involves heating a milled frit containing a blowing agent. The frit can be made by heating the mineral components of the glass at elevated temperatures until molten glass is formed.

The hollow glass microspheres may have any composition, but typically the particles comprise 50 to 90 wt% of SiO ₂ , 2 to 20 wt% of alkali metal oxide based on the total weight. As other components, B ₂ O ₃ , sulfur, divalent metal oxides (for example, CaO, MgO, BaO, SrO, ZnO or PbO), trivalent metal oxides (for example, Al ₂ O ₃ , Fe ₂ O ₃ or Sb ₂ O ₃ ), SiO ₂ and other tetravalent metal oxides (for example, TiO ₂ , MnO ₂ or ZrO ₂ ), oxides of pentavalent atoms (for example P ₂ O ₅ or V ₂ O ₅ ), And the like.

Hollow glass microspheres of various sizes may be useful. In one embodiment, the hollow glass microspheres may have an average diameter in the range of 14 to 45 [mu] m. In some embodiments, it may have an average diameter in the range of 15 to 40 mu m, 20 to 45 mu m, or 20 to 40 mu m.

The hollow glass microspheres are preferably contained in an amount of 1 to 7 wt%, and most preferably 3 to 7 wt%, based on the total weight of the mixture. When the content of the hollow microspheres is less than 1 wt%, the hollow microspheres serve as a nucleating agent for inducing aggregation of the organic clay, which can inhibit the dispersion of the organic clay. When the content exceeds 7 wt% , Coagulation of the hollow glass microspheres occurs, and the effect of dispersing the organic clay may be insufficient. When the content of hollow microspheres is 1 to 7 wt%, hollow glass microspheres and organic clay can improve the melting temperature by restricting the movement of the polymer chain which reduces chain motility.

In an embodiment of the present invention, the hybrid composites comprising hollow glass microspheres increased the melting temperature by about 13.5 ° C as the hollow glass microspheres content increased and contained 5 wt% hollow glass microspheres and organic clay Of the hybrid composites showed the highest T _m values at 161 ° C.

In the present invention, an organic layered clay refers to a clay particle treated with an organizing agent that provides ammonium ion or phosphonium ion, and the cation of the clay particle is replaced with an ammonium ion or a phosphonium ion.

The organic layered clay may be selected from the group consisting of montmorillonite, bentonite, kaolinite, mica, hectorite, fluorite hectorite, saponite, bederite, nontronite, stevensite, vermiculite, halosite, , Kenyaite and pyrophyllite may be treated with an organizing agent which provides an ammonium ion or a phosphonium ion. That is, the organic layered clay may be one in which the cation of the clay is replaced by ammonium ion or phosphonium ion of the organizing agent.

The organic agent may be selected from the group consisting of dimethyl dihydrogenated tallow ammonium, dimethyl benzyl hydrogenated tallow ammonium and dimethylbenzyl dehydrated tallow (2-ethylhexyl) ammonium (dimethyl hydrogenated-tallow (2-ethylhexyl) ammonium).

Preferably montmorillonite (MMT) of the smectite type can be used as the organic clay. The MMT consists of several laminated layers with a thickness of about 1 nm with alumina centrally located in octahedral sheet sandwiched between two silica tetrahedral sheets. The regular spacing between these layers is called the d-spacing or base spacing (d001) and is calculated from the (001) harmonic obtained from the X-ray diffraction pattern.

The organic layered clay is preferably contained in an amount of 0.1 to 20 wt%, more preferably 0.5 to 10 wt%, based on the total weight of the mixture. When the content is less than 0.1 wt%, the effect of increasing the physical properties due to the dispersion of the clay layer is insignificant. When the content is more than 20 wt%, the aggregation phenomenon occurs between the clay particles and the dispersibility into the nanoscale decreases. .

Organic layered clay requires a large aspect ratio in order to maximize the increase of the physical properties of the nanocomposite due to the dispersion of the clay layer. Preferably, the aspect ratio of the organic layered clay may range from 200 to 500, more preferably at least 500.

In order to successfully insert the organic layer structure between polyolefin chains, shear energy and residence time must be sufficient. Therefore, in the present invention, melt extrusion is preferably carried out at a barrel temperature of 180 ° C to 230 ° C, a rotational speed of 30 to 80 rpm and a residence time of 3 minutes to 10 minutes.

The barrel temperature upon melt extrusion may be from 180 캜 to 230 캜. If the barrel temperature is lower than 180 ° C, the melt can not be processed smoothly because the melt can not be processed. If the barrel temperature is higher than 230 ° C, the molecular weight and mechanical properties may decrease due to thermal decomposition of the polymer. In order to overcome the thermodynamic affinity between the clay layers and further disperse at the nanoscale, a high shear stress is required, and therefore, it is more preferable to manufacture by kneading at a high temperature near the melting temperature of the polypropylene resin.

If the residence time is less than 3 minutes, the dispersibility may be decreased. If the residence time is more than 10 minutes, pyrolysis of the polymer may occur.

In the production of the polyolefin-organic clay nanocomposite of the present invention, a kneader such as a uniaxial extruder, a rotating twin-screw extruder, a twin-screw twin-screw extruder, a continuous stirrer, and a kneader capable of applying shear stress by rotation of a screw or a rotor .

A polyolefin according to the above production method; An organic layered clay melted and inserted into the polyolefin chain; And hollow glass microspheres used to disperse the organic layered clay. The polyolefin-organic clay hybrid nanocomposite according to the present invention can be obtained.

The nanocomposite of the present invention may be a gas barrier polyolefin-organic clay hybrid nanocomposite having barrier properties remarkably improved by significantly improving the interlayer distance of the organic clay through the improvement of the dispersion of the organic clay including HGM to increase the crooked path .

In the nanocomposite of the present invention, the interlayer distance of the organic clay may be 33.19 to 33.44 Å. In the embodiment of the present invention, the interlayer distance value of the nanocomposite containing only the organic clay was 31.75 Å, but the interlayer distance of the clay nanocomposite with the hollow glass microsphere was significantly increased from 33.19 to 34.22 Å (See Table 4). From this, it can be seen that the hollow glass microspheres contained in the polymer matrix act as a ball mill in the melt extrusion process to impart a shear force for dispersing the clay in the matrix, thereby dispersing the organic clay and increasing the interlayer distance.

The nanocomposite of the present invention may have a tensile stress at the yield point of 32.58 to 33.40 MPa, a tensile strength of 33.06 to 36.92 MPa, and an elongation of 255 to 330%. In the examples of the present invention, it was confirmed that the addition of HGM to the PPN composite significantly increased the tensile stress at the yield point except for the PPNG7 sample (see Table 5). This increase in strength is due to the increase in the clay middle layer due to the HGM clay crushing effect as well as the PP matrix reinforcement effect of HGM. In addition, it was confirmed that the surface adhesion of the filler and the PP matrix was improved due to the surface of the HGM, thereby improving the tensile stress (see FIG. 5).

The polyolefin-organic clay hybrid nanocomposite of the present invention may further contain additives such as an antioxidant, a heat stabilizer, an antistatic agent, a nucleating agent, a flame retardant, a weather stabilizer, a lubricant, a pigment or a dye, May be added within a range not to deviate from the characteristics of the present invention.

The present invention can provide a barrier film made from the polyolefin-organic clay hybrid nanocomposite.

Preferably, the barrier film of the present invention is 20 ℃ in the thickness 1㎛, the oxygen transmission rate at 90% RH can be less ^{than, 80 cc · mm / m 2} · day · atm.

The barrier film of the present invention includes the nanocomposite in which the highly dispersed layered organic clay is melted and inserted into the polyolefin chain, so that the mechanical properties and thermal stability are improved, and the gas barrier property can be remarkably improved.

Another aspect of the present invention provides a plastic substrate comprising the barrier film. The plastic substrate of the present invention includes the barrier film to ensure the above-mentioned mechanical properties and thermal stability, thereby prolonging the life of the substrate and securing gas barrier properties.

According to the present invention, by using hollow glass microspheres, the weight is reduced, the degree of dispersion of the organic clay is increased, the interlayer distance of the layered organic clay is increased, and the mechanical properties such as tensile stress, tensile strength and elongation, It is possible to manufacture a nanocomposite having a high gas-barrier property.

According to the present invention, a barrier film having excellent mechanical properties and thermal stability, excellent gas barrier property, and a plastic substrate containing the barrier film can be produced.

(b) 손실 탄성률,

(c) 및 (d) 체류 시간의 함수로서 순수 폴리프로필렌 및 폴리프로필렌 복합체의 점도,

도 3은 순수 폴리프로필렌(PP), 폴리프로필렌/유기 점토 복합체(PPN) 및 폴리프로필렌/유기 점토/HGM 복합체(PPNG)의 유변학적 분석 결과이다: (a) 저장 탄성률,

(b) 손실 탄성률,

(c) 복합 점도,

도 4는 중공상 유리 미소구의 SEM 이미지 및 EDX 스펙트럼이다: (a) HGM, (b) HGM 표면 상의 폴리프로필렌.
도 5는 PP 나노복합체(PPN, PPMN)(확대배율 x 2.50k) 및 PP 하이브리드 복합체(PPNG)의 SEM 현미경 사진이다(확대배율 x 400, x 2.50k).
도 6은 유기 점토 및 HGM로 구성된 이성분계 충전 시스템의 모식도이다.Fig. 1 (a) T _m , (b) Tc curve of pure polypropylene and polypropylene nanocomposite.
Figure 2 shows the flow-through results of pure polypropylene, polypropylene / organic clay composite (PPN) and polypropylene / organic clay / PP-g-MA composite (PPMN)

(b) loss modulus,

(c) and (d) the viscosity of pure polypropylene and polypropylene composites as a function of residence time,

Figure 3 shows the results of a rheological analysis of pure polypropylene (PP), polypropylene / organic clay composite (PPN) and polypropylene / organic clay / HGM composite (PPNG)

(b) loss modulus,

(c) complex viscosity,

4 is an SEM image and EDX spectrum of hollow glass microspheres: (a) HGM, (b) polypropylene on the HGM surface.
5 is an SEM micrograph (magnification x 400, x 2.50 k) of a PP nanocomposite (PPN, PPMN) (magnification x 2.50k) and PP Hybrid Composite (PPNG).
6 is a schematic diagram of a two-component filling system composed of organic clay and HGM.

Hereinafter, the present invention will be described in more detail with reference to Examples. These embodiments are only for describing the present invention more specifically, and the scope of the present invention is not limited by these examples.

Materials Used

(PP-g-MA) resin (QB510T) was obtained from Samsung Total (Korea) and polypropylene (PP402, grade of melt: 7g / 10min, 230 DEG C, 2.16kg ASTM D1238) Grade, melt index: 3 g / 10 min, 230 캜) was purchased from Mitsui Chemicals (Japan). Organic clay [Cloisite ^® 20A, montmorillonite] was used as obtained from Southern Clay Products (USA). In the case of Cloisite ^® 20A, the quaternary ammonium used as an organic modifier in the clay was dimethyl dehydrated tallow ammonium and most of the double bonds were hydrogenated. The modified concentration of Cloisite® 20A was 95 meq / 100 g clay. The hollow glass microspheres (HGM) were Glass Bubble (iM30K) purchased from 3M (USA) with an average diameter of 18 microns and an isostatic crush strength of 28,000 psi. All fillers were vacuum dried at 80 ° C for 12 hours to remove residual moisture and used.

Examples 1 to 4 and Comparative Examples 1 to 6: Preparation of nanocomposite

A Brabender microcomputer TSC 42/6 (Brabender®, Duisburg, Germany), designed with a small conical, counter-rotating twin screw compounder with a barrel capacity of 50 g and a screw diameter of 42 mm (L / D = 6) And used for manufacturing.

Based on the specifications of the polypropylene provided by the manufacturer and preliminary experiments, the fillers were dried in a vacuum oven at 80 DEG C for 12 hours before compounding.

In order to evaluate the effect of PP-g-MA and HGM on the formation of the nanocomposite, the contents of PP-g-MA and HGM were varied, while the content of organic clay was fixed at 5 wt% Organic clay / PP-g-MA nanocomposite (PP nanocomposite, PPMN) (Comparative Examples 3 to 6) and PP / organic clay / HGM composite (Comparative Example 2) (PP Hybrid Composites, PPNG) (Examples 1 and 4) were prepared by a melt extrusion process at a barrel temperature of 200 DEG C at a rotation speed of 50 rpm and a residence time of 5 minutes. In Table 1, PPMN5 means a PP / organic clay / PP-g-MA nanocomposite with a PP-g-MA content of 5 wt% and PPNG5 means a PP / organic clay / HGM nano- ≪ / RTI >

sample PP (wt%) PP-g-MA (wt%) Organic clay (wt%) HGM (wt%) Comparative Example 1 (pure PP) 100 - - - Comparative Example 2 (PPN) 95 - 5 - Comparative Example 3 (PPMN5) 90 5 5 - Comparative Example 4 (PPMN10) 85 10 5 - Comparative Example 5 (PPMN15) 80 15 5 - Comparative Example 6 (PPMN20) 75 20 5 - Example 1 (PPNG1) 94 - 5 One Example 2 (PPNG3) 92 - 5 3 Example 3 (PPNG5) 90 - 5 5 Example 4 (PPNG7) 88 - 5 7

After pelletization, the residual amount of the filler in the composite particles was analyzed using a thermogravimetric analyzer (Model: Q500, TA Instruments, USA).

After drying at 80 ° C for 12 hours, the composite particles were compression molded into a film, oxygen barrier properties were measured, and injection, molding, morphological and rheological properties were measured.

Compression molding was performed at 200 占 폚 by using a QMESYS hot press system (QM900A, Quality & Measurement System, Korea) for 4 minutes of preheating, 1 minute of pressure and 4 minutes of cooling.

Using a Xplore Micro 10 cc injection molding machine (Xplore Instruments, Geleen, The Netherlands) for characterization, a disk shape with a diameter of 25.4 mm and a thickness of 1 mm at 200 ° C, and a disk shape with a length of 50 mm, a width of 4 mm and a thickness of 2 mm, Dogbone "shape was injection molded.

Experimental Example 1: Evaluation of thermal properties

The residual amount of clay in the nanocomposite samples was evaluated using thermogravimetric analysis (Model: Q500, TA Instruments, USA).

The test was carried out at a heating rate of 10 DEG C / min at a temperature of up to 600 DEG C in a nitrogen atmosphere. The crystallinity (Xc) was analyzed with a differential scanning calorimeter (model: Q2000, TA, USA).

The sample was placed in a packaged aluminum pan and then heated to < RTI ID = 0.0 > 300 C < / RTI >

The following equation was used to calculate Xc:

Where ΔH is the heat of fusion at the melting point of the sample (J / g), and ΔH ₁₀₀ is a reference value representing the heat of fusion for the 100% α-crystalline polymer. In the case of PP,? H ₁₀₀ is 209 J / g, and? Is the weight fraction of the filler.

The TGA results of the composite samples are shown in Table 2 below.

sample Clay residue (wt%) at 500 ° C sample Clay residue (wt%) at 500 ° C Comparative Example 1 (pure PP) - Comparative Example 2 (PPN) 2.00 ± 0.27 Comparative Example 3 (PPMN5) 2.89 ± 0.12 Example 1 (PPNG1) 3.88 + 0.07 Comparative Example 4 (PPMN10) 2.90 + 0.08 Example 2 (PPNG3) 4.58 ± 0.08 Comparative Example 5 (PPMN15) 2.80 ± 0.12 Example 3 (PPNG5) 6.00 0.35 Comparative Example 6 (PPMN20) 2.84 ± 0.15 Example 4 (PPNG7) 7.57 ± 0.19

In the initial processing step, 5 wt% of organic clay was added to the PP matrix for all PPMN (Comparative Examples 3 to 6) and PPNG (Examples 1 to 4) samples.

As shown in Table 2, PP / g-MA containing PP / clay nanocomposite (PPMN) (Comparative Examples 3 to 6) contained PP-g-MA-free PP / clay nanocomposite (PPN) , The clay content is about 1 wt%. This may be because the polar MA interacts with the organically modified clay such that the nanocomposite during mixing can contain a larger amount of clay.

On the other hand, the PP / organic clay / HGM composite (PPNG) according to the present invention has a maximum residual clay content of 7.57 wt%. This may be because the HGM disperses the clay within the PP matrix so that the nanocomposite can contain a greater amount of clay.

The results of differential scanning calorimetry (DSC) of the composite samples are shown in Table 3 below.

sample Crystal temperature
T _c (° C) Melting temperature
T _m (° C) Fusion heat
? H _m (J / g) Crystallinity
X _c (%) Comparative Example 1 (pure PP) 100.33 + - 0.40 147.51 ± 0.62 ^ab 62.5 ± 0.71 29.90 ± 0.34 ^bc Comparative Example 2 (PPN) 103.25 + 0.14 145.85 ± 0.21 ^a 63.5 ± 2.12 30.38 ± 1.01 ^c Comparative Example 3 (PPMN5) 111.93 + - 0.30 148.87 ± 1.46 ^ab 56.0 ± 2.83 26.79 ± 1.35 ^a Comparative Example 4 (PPMN10) 112.56 ± 0.17 148.79 ± 3.18 ^ab 58.7 ± 1.15 28.07 ± 0.55 ^ab Comparative Example 5 (PPMN15) 112.97 ± 0.08 149.17 ± 2.46 ^ab 58.0 ± 1.00 27.75 ± 0.48 ^a Comparative Example 6 (PPMN20) 114.19 ± 0.63 150.62 + 1.27 ^b 56.5 ± 3.54 27.03 + - 1.69 ^a Example 1 (PPNG1) 113.32 + - 0.47 150.45 ± 0.51 ^b 58.5 ± 2.12 28.10 ± 1.02 ^ab Example 2 (PPNG3) 115.32 ± 0.20 159.47 ± 0.94 ^cd 63.5 ± 0.71 30.52 + - 0.34 ^c Example 3 (PPNG5) 117.85 +/- 0.40 161.00 + 0.08 ^d 65.5 ± 0.71 31.53 + - 0.34 ^c Example 4 (PPNG7) 112.67 ± 0.36 155.99 + - 0.98 ^c 56.5 ± 0.71 27.24 + - 0.34 ^a

In the above table, with respect to the characters indicated by superscripts after the data, different letters in the same column indicate statistically significant differences at a confidence level of 95% (? = 0.05).

As shown in Table 3, the crystal temperature of the PP / organic clay / PP-g-MA nanocomposite (PPMN) (Comparative Examples 3 to 6) was higher than that of the PP / organic clay nanocomposite (PPN) . This increase in the crystallization temperature is due to the reaction of the carbonyl group to maleic anhydride and polypropylene, which serve as nucleating agents in the polypropylene.

In the PPNG nanocomposites (Examples 1 to 4), as the HGM content was increased, the melting temperature was increased by about 13.5 ° C, and the hybrid composite containing 5 wt% HGM and organic clay had the highest T _m value at 161 ° C .

HGM clusters can inhibit the movement of polymer chains that reduce chain mobility at HGM contents of 3 to 5 wt% or less. When HGM content is 7 wt%, HGM clusters are formed in HGM, and HGM clusters are molecules It is presumed that more slip between the chains can reduce the melting temperature.

The crystallinity (Xc) decreased with the addition of clay and HGM, which may be because both PP-g-MA and HGM interfere with the movement of the polymer chains so that the polymer chains are not rearranged.

Experimental Example 2: Evaluation of Structural Characteristics

The structure measurement of the composite material was carried out by X-ray diffraction (model: D / Max-2500, Rigaku, Japan) using Cu Kα radiation with a wavelength of 1.5406 Å. The diffraction spectrum is obtained in the 2 [theta] range of 2 to 10 [deg.], And the interlayer spacing (d001) is calculated using the Bragg equation:

Where? Is the wavelength,? Is the diffraction angle, and d is the interlayer spacing between the clays.

Table 4 shows X-ray diffraction analysis results of pure polypropylene, polypropylene nanocomposite (PPN, PPMN) and polypropylene hybrid composite (PPNG).

sample 2Θ angle (°) Interlayer distance (d ₀₀₁ (Å)) Comparative Example 1 (pure PP) 3.56 24.80 Comparative Example 2 (PPN) 2.78 31.75 Comparative Example 3 (PPMN5) 2.58 34.22 Comparative Example 4 (PPMN10) 2.58 34.22 Comparative Example 5 (PPMN15) 2.60 33.95 Comparative Example 6 (PPMN20) 2.62 33.69 Example 1 (PPNG1) 2.58 34.22 Example 2 (PPNG3) 2.64 33.44 Example 3 (PPNG5) 2.66 33.19 Actual Example 4 (PPNG7) 2.64 33.44

The interlayer distance of pure polypropylene (PP) before melting treatment was about 24.8 Å, but the interlayer distance value of polypropylene (PPN) (Comparative Example 2) nanocomposite was significantly increased to 31.75 Å. This suggests that the insertion of organic clay in the polypropylene matrix occurred. There are two main mechanisms for the dispersion of all types of nanofillers: erosion and rupture. The erosion mechanism was dominant under long low shear stresses, while the rupture mechanism occurred under high shear stresses. These two mechanisms affected the insertion of the middle layer of organic clay. In the case of commercialized samples, the 2θ angle values tend to decrease, suggesting an increase in the interlayer distance.

The amount of compatibilizers did not significantly affect the increase of interstory distance. On the other hand, the addition of HGM to the composite (Examples 1 to 4) showed the same effect when the interlayer distance of the clay increased from 31.75 Å to 33.19 Å to 34.22 Å. Therefore, it can be seen that, in the polymer matrix, HGM behaves as a ball mill to impart shear stress for clay dispersion in the matrix.

Experimental Example 3: Evaluation of rheological properties

Vibration shear measurements in the linear viscoelastic (LVE) region and stress relaxation were carried out using an Anton Paar vibratory rheometer (model: Physica) using a parallel plate structure (diameter 25 mm and gap 1 mm) MCR 302, Anton Paar GmbH, Austria). A frequency sweep was performed after approximately three minutes of temperature equilibration with a frequency decreasing from 100 rad / s to 0.1 rad / s and a strain at 1%.

Figures 2 and 3 show the changes in viscosity behavior of the filler dispersion in the polymer composite by rheological analysis. All specimens except PPNG7 showed Newtonian plateau in the complex viscosity curve at low frequency, but showed a pseudo-plastic tendency at high frequencies. However, PPNG7 samples were observed as plastic behavior in all frequency regions. It can be inferred that when too much HGM is distributed in the PP matrix, HGM agglomerates or HGM clusters are formed and the viscosity behavior may be different due to agglomeration.

It was observed that the modulus of elasticity and complex viscosity of PP / organic clay nanocomposite (PPN) samples containing 5 wt% organic clay in the PP matrix decreased dramatically in all frequency ranges. This may be due to chain disruption or molecular staggering during processing. Figure 2 (d) shows the composite viscosity of PP during mixing in an extruder for 5 minutes at high shear stress and temperature. The same effect appears in composites containing nanoclay. As the content of PP-g-MA and HGM in the PP / organic clay nanocomposites increased, the storage modulus at low frequencies gradually increased on the same slope.

The low frequency dependence of loss storage shows a similar tendency as shown in FIG. 3 (b), but the corresponding increase of G "is higher than G '. As the content of PP-g-MA in PPN samples increases, the storage and low elastic modulus increase slightly at low frequencies. This shows the effect of compatibilizers on interfacial interactions and nanoclay dispersion in the polymer matrix.

Experimental Example 4: Evaluation of morphological characteristics

The shape of the polypropylene composite was observed with a field emission scanning electron microscope (Model: SU8020, Hitachi, Japan). The injection molded sample was frozen in liquid nitrogen and then crushed. All crushed sections were coated with Pt / Pd alloy using ion sputter (E-1045, Hitachi, Japan) and subjected to a characterization test under high vacuum at an acceleration voltage of 2 kV.

Specifically, the chemical composition of HGM was evaluated using an EMAX energy dispersive X-ray spectrometer (EDX) (HORIBA scientific, Japan). FIG. 4 is a SEM micrograph of the HGM powder dispersed in the polypropylene matrix, and SEM shows that the HGM powder is dispersed in the polypropylene matrix by EDX. It was confirmed by EDX that the polypropylene was attached to the surface of the HGM. It was also found that the carbon content was significantly increased by the EDX spectrum as compared with the HGM powder. Therefore, it was confirmed that excellent interfacial adhesion was formed between the HGM and the polypropylene matrix.

PP / organic clay nanocomposite (PPN) (Comparative Example 2), PP / organic clay / PP-g-MA nanocomposite (PPMN) (Comparative Examples 3 to 6) and PP / organic clay / HGM composite (PPNG) SEM images of fractured sections of dog-bone specimens taken after testing for Examples 1 and 4 are shown in FIG. The organic clay is firmly embedded in the polypropylene matrix. As the weight fraction of HGM is increased, the number of HGM is increased, and it is confirmed that the deposit is present on the surface of the HGM dispersed in the PP matrix.

Experimental Example 5: Evaluation of mechanical properties

(50 mm in length, 4 mm in width, and 4 mm in thickness) molded by injection molding using an Instron 3367 universal testing machine (INSTRON, MA, USA) equipped with a 30 kN cell force 2 mm) were evaluated for mechanical properties. The tensile strength and breaking point of the dog-bone type injection molded samples were measured by measuring the force against the displacement of each sample at 10 mm / min. At least five samples were tested for each mixed sample and three values were applied except for the maximum and minimum values. Table 5 below shows the results.

sample Tensile stress at yield point (MPa) Tensile Strength (MPa) Elongation at break (%)
Comparative Example 1 (pure PP) 26.84 ± 0.36 ^ab 33.50 + - 0.75 ^c 342.98 +/- 13.22 ^cd Comparative Example 2 (PPN) 27.61 ± 0.86 ^ab 36.01 ± 0.19 ^d 389.95 +/- 14.35 ^e Comparative Example 3 (PPMN5) 27.65 ± 0.87 ^abc 32.13 + - 0.82 ^abc 353.12 ± 3.14 ^cd Comparative Example 4 (PPMN10) 27.50 ± 0.50 ^ab 32.29 ± 0.60 ^bc 352.80 +/- 16.01 ^cd Comparative Example 5 (PPMN15) 27.08 ± 0.76 ^ab 32.69 + - 0.56 ^c 371.66 ± 9.20 ^de Comparative Example 6 (PPMN20) 28.51 ± 0.47 ^bc 33.30 ± 0.23 ^c 364.49 ± 5.86 ^de Example 1 (PPNG1) 29.44 + - 0.95 ^c 30.49 + - 0.51 ^a 303.55 + 3.94 ^b Example 2 (PPNG3) 32.90 ± 0.21 ^d 36.03 ± 0.89 ^d 320.46 ± 10.46 ^bc Example 3 (PPNG5) 32.99 + - 0.41 ^d 33.59 ± 0.53 ^c 266.63 ± 11.37 ^a Example 4 (PPNG7) 25.85 + 0.47 ^a 30.87 ± 0.34 ^ab 303.07 ± 23.16 ^b

In the above table, with respect to the characters indicated by superscripts after the data, different letters in the same column indicate statistically significant differences at a confidence level of 95% (? = 0.05).

As shown in Table 5, when 5 wt% of organic clay was added to polypropylene (PPN), the tensile stress was improved by 7.49% and the elongation at break was improved by 13.7%. This seems to be due to the reinforcing effect of the organic clay on the polypropylene matrix.

From studies based on the higher interactions achieved between polar groups of conventional maleic anhydride (MA) grafted polypropylene (PP-g-MA) and organic clays, it has been found that functional groups such as PP-g-MA in the polymer matrix It has been reported that the addition of a polymer having a high molecular weight can improve mechanical properties. However, the experimental results show that PPMN samples with PP-g-MA added to the composites show a significant decrease in tensile strength compared to pure polypropylene. It can be inferred that the crystallization behavior is interrupted by the chain branch of maleic anhydride (MA) on the polypropylene, resulting in a reduction in percent crystallinity.

As a result of evaluating the effect of HGM in the polypropylene composite, the tensile stress at the yield point was significantly increased except for PPNG7 (Example 4) as shown in Table 5. This increase in strength is possible because not only the reinforcing effect of HGM in the polypropylene matrix but also the interlayer of the clay is increased as confirmed by XRD analysis due to the clay dispersion effect of HGM. In addition, the surface of the HGM enhanced the interfacial adhesion between the filler and the polypropylene matrix (Figure 5). When the content of HGM exceeds 7 wt%, tensile stress is lowered, which may be due to aggregation of HGM.

Experimental Example 6: Evaluation of oxygen barrier property

Oxygen permeability of the PP composite film was measured by OX-TRAN (Model: 702, MOCON, USA) conforming to ASTM 3985, a sample was prepared using an aluminum mask (5 cm ² ) 23 < 0 > C and 0 < 0 > C. Each sample was conditioned in a chamber for 1 hour and the OTR (OTR) was measured from 24 to 48 hours until stable data was reached.

sample O ₂ transmission
(cc · mm / m ² · day · atm) sample O ₂ transmission
(cc · mm / m ² · day · atm) Comparative Example 1 (pure PP) 94.62 ± 3.73 ^f Comparative Example 2 (PPN) 76.91 + - 5.61 ^bc Comparative Example 3 (PPMN5) 95.34 + - 5.01 ^fg Example 1 (PPNG1) 85.47 ± 0.62 ^de Comparative Example 4 (PPMN10) 102.39 + - 7.22 ^g Example 2 (PPNG3) 64.79 ± 1.96 ^a Comparative Example 5 (PPMN15) 88.77 ± 0.88 ^ef Example 3 (PPNG5) 72.83 ± 1.76 ^b Comparative Example 6 (PPMN20) 80.60 ± 1.76 ^cd Example 4 (PPNG7) 74.97 ± 0.69 ^bc

* Other superscripts in the same column indicate statistically significant differences at the 95% confidence level (α = 0.05).

Table 6 shows the O ₂ permeability of pure polypropylene film and polypropylene composite film. It is widely known that films made from pure polypropylene have poor O ₂ barrier properties. The pure polypropylene film shows an oxygen permeability of 94.62 ± 3.73 cc · mm / m ² · day · atm.

PPN films with 5 wt% organic clay added to polypropylene showed a decrease in oxygen permeability of 23%, and PPMN films showed no significant change in permeability even with different contents of PP-g-MA . Therefore, it was confirmed that PP-g-MA had no significant effect on the permeability of PP / clay nanocomposite. PP-g-MA has a positive effect on the dispersion of the nanoclay, but it decreases the oxygen barrier due to the increase in the free volume of the polymer matrix due to the branched MA. On the other hand, PP nanocomposite films containing HGM have a significant effect on improving the oxygen barrier, especially PPNG3 sample (HGM 3 wt%) showed the best performance to reduce the oxygen permeability to 46% compared with pure PP .

The interfacial cavities and cracks between the polymer and the HGM may reduce the barrier properties, but the interfacial adhesion between the polymer and the HGM was found to be sufficient to improve the barrier properties as identified in FIG. As the amount of HGM increased, O ₂ transmission rate to decrease closer to the O ₂ permeability of the original PPN film, which may be aggregated in HGM, that is, the HGM cluster due to create a larger space at the interface between the polymer and the HGM.

Claims (13)

Preparing a polyolefin, an organic layered clay and a hollow glass microsphere-containing mixture (step 1); And
(Step 2) of dispersing the organic layered clay by means of the ball milling action of the hollow glass microspheres and inserting the organic layered clay between the polyolefin chains by introducing the mixture into a melt extruder, applying shear stress and melt extrusion, Wherein the polyolefin-organic clay hybrid nanocomposite is a polyolefin-organic clay hybrid nanocomposite. The method according to claim 1,
The organic layered clay may be selected from the group consisting of montmorillonite, bentonite, kaolinite, mica, hectorite, hectorite, saponite, bederite, nontronite, stevensite, vermiculite, halosite, Organic clay hybrid nanocomposite wherein at least one clay selected from the group consisting of strontium titanate, kenyanite, and pyrophyllite is treated with an organizing agent that provides an ammonium ion or a phosphonium ion. 3. The method of claim 2,
The organizing agent may be selected from the group consisting of dimethyl dihydrogenated tallow ammonium, dimethyl benzyl hydrogenated tallow ammonium and dimethylbenzyl dehydrated tallow (2-ethylhexyl) ammonium (dimethyl hydrogenated tallow ammonium) -tallow (2-ethylhexyl) ammonium). < / RTI > The method according to claim 1,
Wherein the organic layered clay is contained in an amount of 0.1 to 20 wt% based on the total weight of the mixture. The method according to claim 1,
Wherein the polyolefin is contained in an amount of 50 to 99 wt% based on the total weight of the mixture. The method according to claim 1,
Wherein the hollow glass microspheres are comprised between 1 and 7 wt% based on the total weight of the mixture. The method according to claim 1,
Wherein the melt extrusion is carried out at a barrel temperature of 180 ° C to 230 ° C, a rotational speed of 30 rpm to 80 rpm and a residence time of 3 minutes to 10 minutes. 8. A process for the preparation of a compound according to any one of claims 1 to 7,
Polyolefin; An organic layered clay melted and inserted into the polyolefin chain; And hollow glass microspheres used to disperse the organic layered clay. ≪ RTI ID = 0.0 > 21. < / RTI > 9. The method of claim 8,
Wherein the hollow glass microspheres are contained in an amount of 1 to 7 wt% based on the total weight of the nanocomposite. 9. The method of claim 8,
Organic clay hybrid nanocomposite wherein the interlayer distance of the organic clay is from 33.19 to 33.44 Å, the tensile stress at the yield point is from 32.58 to 33.40 MPa, the tensile strength is from 33.06 to 36.92 MPa, and the elongation is from 255 to 330%. A barrier film made from the polyolefin-organic clay hybrid nanocomposite of any of claims 8 to 10. Of claim 11 wherein, the 20 ℃, the oxygen transmission rate at 90% RH in the thickness 1㎛, 80 cc · mm / m 2 · day · atm or less, the barrier film to. A plastic substrate comprising the barrier film of claim 12.

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