KR100522137B1 - A method for preparing polymer / clay nanocomposites by using reactive extrusion - Google Patents

Abstract

The present invention relates to a composite material for filling nano-sized inorganic particles into general-purpose resins or engineering plastics, and more particularly, to a polymer capable of reactive extrusion such as nylon 6 The present invention relates to a technology for preparing nanocomposites in which clays such as sodium-montmorillonite, which are used as inorganic fillers, are evenly dispersed in nanoscale units during polymerization. According to the present invention, a nanocomposite having an improved dispersion state can be obtained by mixing monomers and clays in advance at a molecular level and then reacting them in a twin screw extruder or by adding and mixing clays during polymer polymerization in a twin screw extruder. The nanocomposites thus prepared exhibit excellent mechanical and thermal properties and low gas permeability and can be applied to structural materials and packaging materials.

Description

Manufacturing Method of Polymer / Clay Nanocomposites Using Reaction Extrusion Process {A METHOD FOR PREPARING POLYMER / CLAY NANOCOMPOSITES BY USING REACTIVE EXTRUSION}

Composite material is a processing method that not only improves mechanical and thermal properties of existing materials but also increases numerical stability and wear resistance, and is a representative field of processing technology that is widely applied in all fields related to materials such as polymers, metals, and ceramics. can do.

Research on increasing the utilization of inorganic reinforcing materials such as glass fiber or carbon fiber to polymers has been conducted for several decades. Recently, research on nanocomposites made using nano-sized reinforcing materials has been actively conducted. It is becoming. When using nano-size inorganic fillers such as clay, it is known that the production of composites having very excellent physical properties is possible even at a small filler content of 5 to 20 wt% or less. Clay exists in a natural state in which silicate layers (silicate layers), which are inorganic minerals, are stacked, and each silicate layer has a wide plate shape having a thickness of 1 nm and a width of 1 μm. The high aspect ratio and the large surface area of the clay silicate layer effectively serve as reinforcing materials through the mixing with the polymer and enable the production of nanocomposites with high physical properties.

The research on nanocomposites made by mixing clay with polymers is based on the use of nylon 6 / clay nanocomposites manufactured by filling nylon 6 with clay at Toyota Motor Research Institute of Japan in the mid-1970s. have. Until now, a lot of research has been conducted on polymer / clay nanocomposite manufacturing technology.

The first is to melt-mix the clay using a polymer and twin screw extruder, so that the chain of molten polymer spreads between layers of clay by shear stress of the extruder, thereby increasing the distance between the layers of clay. There is a melt-intercalation method. In this case, by adding hydrophobic functional groups to the hydrophilic clay to increase the compatibility with the polymer, or by adding a reactive functional group capable of reacting with the polymer material to enhance the reaction compatibility with the polymer, the polymer chain is effectively infiltrated between the layers of the clay. An attempt was made. This method has the advantage of being able to work continuously, but because it already uses polymers with sufficiently long molecular chains, the initial objective of making nanocomposites with exfoliated structures was not achieved by increasing the distance between layers of clay. Caused.

The second method is an in-situ polymerization method in which clay is dispersed in a monomer state and then polymerized. In this case, the polymerization of the polymer occurs between the layers of clay, which results in the best agreement with the initial intention to increase the distance between the layers of clay rather than the melt-intercalation method. However, since the in-situ polymerization method is polymerized through a polymerization time of 10 to 20 hours through a non-continuous reactor such as a batch type at a high temperature, the in-situ polymerization method has a very weak disadvantage in terms of productivity and economy.

As a patent document on the production of nanocomposites using conventional clays, Korean Patent Laid-Open Publication No. 2003-27157 discloses a coupling agent and a nylon 6 polymer using an organicized clay surface-treated with an organic agent containing an alkyldiamine group at its end. Nylon 6 nanocomposite prepared by compounding by melt mixing with resin is a method for producing nanocomposite which improves the low elongation and impact strength of the conventional nylon 6 nanocomposite due to the structural change of the new melting point from 230 ℃ to 250 ℃ Is disclosed.

US Pat. No. 65,485,87 describes a method for producing a nanocomposite having a low gas permeability by using two or more organic cations to increase the distance between layers of clay.

In addition, US Pat. No. 6,552,113 describes a method for producing a polymer / clay nanocomposite having improved dispersibility by using an affinity and an amorphous oligomer of an organically treated clay.

Up to now, the manufacturing technology of the polymer / clay nanocomposite has been studied by dividing into the melt-intercalation method and the in-situ polymerization method described above. However, the above manufacturing technique does not satisfy the productivity and the peeling efficiency of the clay at the same time in the production of nanocomposites.

Accordingly, one object of the present invention is to provide a method for producing a polymer / clay nanocomposite that can satisfy both the productivity and the peeling efficiency of the clay when manufacturing the nanocomposite.

More specifically, an object of the present invention, as part of the nanocomposite production technology through a reaction extrusion process, to provide a series of manufacturing method for producing a nanocomposite of the polymer and clay capable of reaction extrusion.

It is another object of the present invention to provide a nanocomposite having improved mechanical properties and thermal properties by optimizing the manufacturing conditions of the polymer / clay nanocomposite.

More specifically, an object of the present invention is to provide a nanocomposite exhibiting excellent physical properties by establishing the process conditions that can effectively break the laminated structure of the clay, evenly dispersed in the polymer.

The inventors of the present invention have been intensively studied to achieve the above object, and have come to complete the present invention by focusing on a method of manufacturing a nanocomposite through a reaction extrusion process.

In other words, the present invention relates to a method for producing a polymer / clay nanocomposite using a reaction extrusion process, to date, in the manufacturing method of the clay nanocomposite has been reported an example of producing a nanocomposite through a reaction extrusion process any group none.

The reaction extrusion process according to the present invention combines the advantages of conventional melt-intercalation and in-situ polymerization, and simultaneously polymerizes and disperses clay in the extruder, thereby polymerizing polymerized / clay nanoparticles. It enables the continuous production of composites. In addition, in the case of the conventional polymerization method, it is necessary to turn the synthesized powdered polymer back into the extruder to produce pellets for easy handling, but the reaction extrusion process does not require such an additional step for sale distribution. Therefore, there is an advantage that the production cost can be lowered.

Unlike the existing polymer polymerization process that performs polymerization in a reactor, the reaction extrusion process is a process of polymerizing a polymer by using an extruder. In the extruder, a material residence time of about several minutes is applicable only when the reaction is fast. . The polymers applicable to the reaction extrusion process according to the present invention and the polymerization method thereof are summarized in the following Table 1.

Polymers and polymerization methods capable of reactive extrusion Polymerization Method Polymer Addition polymerization PMMA (poly (methylmethacrylate)), SAN (styrene-acrylonitrile copolymer), ABS (acrylonitrile-butadiene-styrene copolymer), vinyl polymer, styrene-MAH (maleic anhydride) copolymer Ion polymerization Nylon 6, Nylon 12, POM (poly (oxymethylene)), PS (polystyrene), SBS (styrene-butadiene-styrene copolymer), SIS (styrene-isoprene-styrene copolymer) Addition polymerization method PU (polyurethane), TPU-ABS (thermoplastic polyurethane-acrylonitrile-butadiene-styrene) copolymer, EMC (epoxy molding compound) Condensation polymerization PET (polyethylene terephthalate), PBT (polybutylene terephthalate), polyester, PI (polyimide), PEI (polyether imide), nylon 6,6

Hereinafter, a method for producing nylon 6 / clay nanocomposites using anion polymerization using nylon 6 as a polymer capable of a reaction extrusion process will be described. Hereinafter, the nylon 6 is described as an example of a polymer capable of a reaction extrusion process, but the polymers listed in Table 1 share substantially the same polymerization mechanism as that of Nylon 6, and the technical specificity in the manufacturing method described in the following embodiments is shown in Table 1 It will be apparent to those skilled in the art that the present invention can also be applied to reaction extrusion of other polymers.

Therefore, the following specific examples are provided only for the purpose of explanation, and of course, the manufacturing method of the polymer / clay nanocomposite by the reaction extrusion process of the present invention is not limited to the nylon 6 / clay nanocomposite.

Nylon 6 / Clay Nanocomposite by Ion Polymerization by Reaction Extrusion Process

How to make

The manufacturing process of the present invention is characterized in that the nylon 6 / clay nanocomposite through anionic polymerization, which can be completed in a short time to the reaction extrusion process is possible.

Details of the catalyst, initiator, and clay used in the production of nylon 6 / clay nanocomposites by anionic polymerization are as follows.

The resin composition according to the present embodiment is 72 to 96% by weight of a monomer caprolactam, 2 to 5% by weight of sodium-caprolactam as a catalyst, and 1 to 3% by weight of N-acetylcaprolactam as an initiator, to nylon 6 to be polymerized. Clay in an amount of 0.01 to 20% by weight. At this time, the catalyst and the initiator should be added in a molar ratio of 1: 1. In particular, as the amount of the catalyst and the initiator is increased, the molecular weight of the polymerized nylon 6 decreases, and when it is added more than the above-mentioned content, the molecular weight of the obtained nanocomposite is too low to show low mechanical-thermal properties. If the content is less than the above-mentioned content, it is not preferable that the functionalities of the catalyst are inactivated by the moisture contained in the clay, which causes the polymerization of nylon 6 to be stopped halfway. Due to this phenomenon, the polymerization of nylon 6 is stopped halfway even when the content of clay is 20% by weight or more, so if the content of clay exceeds 20% by weight, it is not preferable. Since the content of the caprolactam as a monomer is an amount determined according to the contents of the catalyst, the initiator and the clay described above, it can be said that there is no specificity due to the change in the original content.

This embodiment provides a method for producing a nanocomposite exhibiting excellent thermal-mechanical properties through the change of process conditions in the production of nylon 6 / clay nanocomposites using an anion polymerization method.

More specifically, when manufacturing the nanocomposite, the nanocomposite is prepared by changing the addition time and content of clay.

Caprolactam, a monomer of nylon 6 used in the present embodiment, is a substance represented by Chemical Formula 1, and has a molecular weight of 113 g / mole and a melting point of 80 ° C., which is present in the form of a solid at room temperature. Wetability is very high, when exposed to the atmosphere absorbs excess water and is dissolved in the form of a liquid itself. The content of the caprolactam in the present invention is 72 to 96% by weight.

Sodium-caprolactam, which is a catalyst of nylon 6 anion polymerization, used in this embodiment is a compound represented by the following Chemical Formula 2, which has a molecular weight of 134 g / mole and a melting point of 80 ° C. Exists as. After the caprolactam is melted in a beaker at 100 ° C, sodium-hydride (NaH) is sufficiently dispersed, and then prepared by slow cooling in air. Similarly to the caprolactam, the wettability is very high, and when exposed to the atmosphere, the excess water may be absorbed to dissolve in a liquid form. In this embodiment, the content of the catalyst prepared as described above is 2 to 5% by weight.

N-acetylcaprolactam, an initiator of the nylon 6 anion polymerization used in the present embodiment, is a compound represented by the following formula (3), which has a molecular weight of 155 g / mole and has a boiling point of 130 ° C. in liquid form at room temperature. Exists as. In this embodiment, the content of the initiator prepared as described above is 1 to 3% by weight.

Clay, the filler used in this embodiment, is sodium-montmorillonite which is not subjected to organic treatment existing in nature, and has a clay interlayer distance of 1.1 nm and exists in powder form at room temperature. It has high wettability and is present in the bond between layers of clay with strong van der Waals forces. In this embodiment the clay is contained in an amount of 0 to 20% by weight based on the content of nylon 6 to be polymerized.

Nylon 6 / clay nanocomposites using the anion polymerization method of the present embodiment may be added additives or the manufacturing method is changed according to various purposes, and the type and method of manufacturing such additives to those skilled in the art Can be appropriately selected.

The nylon 6 / clay nanocomposite prepared according to the present invention exhibits excellent thermo-mechanical properties by exhibiting better clay dispersibility and processing convenience than nanocomposites prepared by conventional melt extrusion or in-situ polymerization.

The production method of the nylon 6 / clay nanocomposite using the anion polymerization method of the present embodiment can be applied to a continuous process such as reaction extrusion, it is not particularly limited to the production method.

As described above, the nylon 6 / clay nanocomposites using the anion polymerization method of the present invention exhibit excellent thermal-mechanical properties. In particular, the manufacturing technology of the present invention can be applied to a process that enables the continuous production of nanocomposites having excellent dispersibility.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples, and those skilled in the art will appreciate that various modifications and supplements to the present invention are possible within the scope of the appended claims.

Example 1

A mechanical stirrer was used for the effective application of caprolactam, while 99% by weight of caprolactam was melted in a 100 ° C oil bath in a closed system with air blocking. In order to prevent the inflow of air, the inside of the reactor was made into a nitrogen atmosphere by continuously flowing a dehumidified nitrogen (N ₂ ) gas. The sufficiently molten caprolactam takes the form of a clear liquid such as clear water, and stirring was continued while slowly injecting 1% by weight of sodium hydride at a rate of 1 g / min. Stirring was continued until the sodium-hydride had sufficiently melted in caprolactam to form sodium-caprolactam resulting in a clear liquid form.

The sodium-caprolactam melt prepared in the reaction was cooled to room temperature in a nitrogen atmosphere desiccator to prepare a solid catalyst. The prepared catalyst was stored in a desiccator in a nitrogen atmosphere to avoid contact with moisture.

Example 2

In order to remove moisture of caprolactam, a monomer of nylon 6, it was dried in an oven at 60 ° C. for 7 days. 93.9% by weight of caprolactam, 1.9% by weight of catalyst and 1.2% by weight of initiator were placed in the first hopper of the twin screw extruder and polymerized in an inert gas atmosphere blocked by external air. At the same time as the initiator was added to the twin-screw extruder, the polymerization reaction of nylon 6 was started, wherein the polymerization time of nylon 6 may vary depending on the amount of additives and moisture content.

After drying for 24 hours in a vacuum oven at 90 ℃ to remove the moisture contained in the clay 3% by weight of clay was added through the second hopper of the twin screw extruder. The nanocomposite was prepared by increasing the clay addition time to 40 seconds, 60 seconds, 80 seconds, 100 seconds, 120 seconds and 140 seconds to prepare nylon 6 / clay nanocomposites according to the clay addition time.

Example 3

Nylon 6 / clay nanocomposites were prepared through a reaction extrusion process. In order to set the point of addition of clay to 80 seconds as in Example 2, the monomer, initiator and catalyst were fed to a twin screw extruder through a first hopper, and clay was supplied to a second hopper. hopper). The monomer, the initiator, and the catalyst, which were added to the twin screw extruder before the clay, started the polymerization, and nylon 6 / clay nanocomposites were prepared through the continuous process by the clay added after the polymerization. The temperature of the extruder was set in the order of 100-180-200-220-240-240 ° C in the die direction from the first hopper, and in an argon (Ar) gas atmosphere to avoid contact with air during the polymerization process. The polymerization process was attempted at.

The monomer, initiator, catalyst and clay used in the polymerization process were dried in the same manner as in Example 2, and nanocomposites were prepared while changing the amount of clay to 1% and 5%. The content of the remaining components according to the clay content is as follows.

With 1% by weight of clay: 95.8% by weight of caprolactam,

2.0 wt% of catalyst,

1.2 wt% of initiator

With 3 weight percent clay: 93.9 weight percent caprolactam,

1.9 wt% of catalyst,

1.2 wt% of initiator

5 wt% clay content: 92.0 wt% caprolactam,

1.9 wt% of catalyst,

Initiator 1.1 wt%

Example 4

As a comparative example of the nanocomposite manufacturing process prepared by reaction extrusion by adding clay during the polymerization of nylon 6 of Example 3, clay was added together with the monomer, the initiator and the catalyst through the first hopper, and the amount of clay added was 1 Nanocomposites were prepared with varying% and 5%. Process conditions of reaction extrusion during polymerization were set in the same manner as in Example 3, and then the process was performed.

Test Example 1: WAXD Analysis

X-ray diffraction analysis was used to measure the distance between clay layers in the nanocomposites prepared in Examples 2, 3 and 4. The prepared nanocomposite was molded in the form of a film through extrusion, and then measured in a range of 2 to 10 degrees under conditions of 100 mA and 40 kV.

Figure 1 shows the WAXD of the nanocomposite prepared by changing the time of adding the clay in Example 2. As the addition time of the clay was increased, the peak intensity of WAXD decreased, and the smallest peak intensity was shown at 80 seconds. In general, the intensity of the WAXD peak represents the interlayer regularity of clay, and the 2θ value of the peak represents the distance between the clays. As the value of 2θ decreases, the interlayer distance increases. If the clay addition time is before 80 seconds, the 2θ value of the peak shows a constant value, but as the value increases to 100 seconds, the 2θ value of the peak also increases. This indicates that the distance between the layers of clay is decreased, and particularly, when the addition time of the clay is 140 seconds, the peak intensity is also increased.

Figure 2 is a view showing the WAXD of the nanocomposite prepared by varying the amount of clay added in Example 3. When the amount of clay added is 1% by weight, the peak intensity is so small that the peak disappears with the naked eye. However, as the amount of clay is increased by 3% by weight or more, the peak intensity tends to become stronger. It can be seen that the 2θ value of the peak shows a constant value regardless of the clay content change.

Figure 3 is a view showing the WAXD of the nanocomposite prepared by melting the clay from the initial reaction in Example 4. When the amount of clay added was 1% by weight, it was possible to confirm the presence of the peak. As shown in FIG. 2, the intensity of the peak also increased as the content of clay increased.

Figure 4 shows the WAXD pattern of the nanocomposite prepared in Example 3 and the nanocomposite prepared in Example 3 when the content of clay is 3% by weight, the nanocomposite prepared in Example 4 shows a strong peak intensity It can be seen. This shows that the clay interlayer regularity of the nanocomposite fabricated in Example 3 was more destroyed than the nanocomposite fabricated in Example 4, and the difference in the time point of the addition of clay had a great influence on the clay dispersibility inside the composite. Suggest.

Through the above analysis results, it can be seen that the nylon 6 / clay nanocomposite prepared by the reaction extrusion by adding the clay in the middle of the polymerization reaction as in Example 2 exhibits excellent clay dispersibility.

Test Example 2: Measurement of mechanical properties of nylon 6 / clay nanocomposite

In order to measure the physical properties of the nylon 6 / clay nanocomposite prepared in Example 3, the specimen was prepared through an injection process and measured as follows.

5 and 6 show the mechanical properties of the nanocomposite prepared in Example 3. In the case of tensile strength, when the amount of clay added was 1% by weight, the maximum value of the physical property was shown, and the result was slightly decreased as the amount added to 3% by weight. However, as the addition amount of clay was increased to 5% by weight, it was possible to confirm a sharp drop in the physical property value, which was lower than that of pure nylon 6. The flexural strength also showed a similar tendency to the above tensile strength, and the physical property value increased as the amount of clay added to 3% by weight. When the amount of clay added was 5% by weight, the decrease in the physical property was confirmed. Could. When the amount of clay added is 5% by weight, the decrease in mechanical properties may be due to a decrease in molecular weight of nylon 6 due to moisture contained in the clay.

Table 2 shows the results of measuring the molecular weight of the nylon 6 / clay nanocomposite prepared in Example 3. As the amount of clay increased, the molecular weight of nylon 6 decreased, and the lowest molecular weight was shown when the content of clay was 5% by weight.

Molecular weight of nanocomposite prepared in Example 3 Clay addition amount (% by weight) Molecular Weight (Mv) 0 One 3 5 32,700 31,900 27,400 24,100

7 is a view showing the results of measuring the composite viscosity (η) of the nylon 6 / clay nanocomposite prepared in Example 3 by ARES. In the same manner as the mechanical property value measurement results, the clay content showed an increased viscosity up to 3% by weight, but when the clay content was 5% by weight, the viscosity was similar to or lower than that of pure nylon 6.

Test Example 3 Measurement of Thermal Properties of Nylon 6 / Clay Nanocomposites

TGA was performed to measure the thermal properties of the specimen prepared in Test Example 3. The pyrolysis temperature of each nanocomposite specimen in a nitrogen atmosphere was measured and the results are shown in Table 3 below.

 Clay content (% by weight) Pyrolysis Temperature (℃)  0  One  3  5 278 290 292 300

As can be seen from Table 3, it can be seen that the thermal decomposition temperature also increases with the amount of clay added. This is because the gas permeation in the polymer is lowered by the clay, which is an inorganic material dispersed in the polymer, which causes thermal decomposition of the nanocomposite at a high temperature.

According to the present invention, the nanocomposite in which the clay is uniformly dispersed in the polymer at a nanoscale by a continuous process such as reaction extrusion has excellent clay dispersibility, mechanical and thermal properties, and thus is applied to equipment housing or structural material production. Can be. In addition, the continuous process by the reaction extrusion of the present invention enables the mass production of clay nanocomposites having excellent physical properties, it is very important as a source technology for mass production of polymer / clay nanocomposites.

1 is a view showing the WAXD of the nanocomposite prepared by changing the time of adding the clay in Example 2.

Figure 2 is a view showing the WAXD of the nanocomposite prepared by varying the amount of clay added in Example 3.

Figure 3 is a view showing the WAXD of the nanocomposite prepared by melting the clay from the initial reaction in Example 4.

4 is a view showing the WAXD pattern of the nanocomposite prepared in Example 3 and the nanocomposite prepared in Example 3 when the content of clay is 3% by weight.

5 is a view showing the tensile strength of the nanocomposite prepared by changing the content of clay in Example 3.

6 is a view showing the bending strength of the nanocomposite prepared by changing the content of clay in Example 3.

7 is a view showing the results of measuring the composite viscosity (η) of the nylon 6 / clay nanocomposite prepared in Example 3 by ARES.

Claims (9)

In the manufacturing method of the clay dispersion polymer resin nanocomposite, (a) PMMA (poly (methylmethacrylate)), SAN (styrene-acrylonitrile copolymer), ABS (acrylonitrile-butadiene-styrene copolymer), and vinyl polymer polymerized by the addition polymerization method; (b) styrene-MAH (maleic anhydride) copolymer, nylon 6, nylon 12, POM (poly (oxymethylene)), and PS (polystyrene) polymerized by ion polymerization; (c) SBS (styrene-butadiene-styrene copolymer), SIS (styrene-isoprene-styrene copolymer), PU (polyurethane), TPU-ABS (thermoplastic polyurethane-acrylonitrile- polymerized by addition polymerization method) Butadiene-styrene) copolymers, and EMC (epoxy molding compound); And (d) PET (polyethylene terephthalate), PBT (polybutylene terephthalate), polyester, polymerized by condensation polymerization method, PI (polyimide), PEI (polyether imide), and nylon 6,6 A method of producing a polymer / clay nanocomposite, characterized in that the clay is uniformly dispersed in nanoscale units as inorganic filler particles while polymerizing the polymer selected from the corresponding monomers by a continuous process through reaction extrusion. The method of claim 1, wherein the clay is mixed with a monomer from the beginning and then prepared through a reaction extrusion process. The method for producing a polymer / clay nanocomposite according to claim 1, wherein clay is added in the middle of the reaction during polymer polymerization in a reaction extrusion process. The method for producing a polymer / clay nanocomposite according to claim 1, wherein the clay is dispersed while polymerizing nylon 6 using an anionic polymerization method by a reaction extrusion process using caprolactam as a monomer. 5. The method of claim 4, wherein the clay is mixed with caprolactam from the beginning and then subjected to nylon 6 polymerization. 6. The method for producing a polymer / clay nanocomposite according to claim 4, wherein clay is added in the middle of the polymerization of nylon 6. The method of producing a polymer / clay nanocomposite according to claim 4, wherein the number average molecular weight of the polymerized nylon 6 is in the range of 10,000 to 100,000. The method for producing a polymer / clay nanocomposite according to any one of claims 1 to 7, wherein the clay is sodium-montmorillonite in its natural state which is not subjected to an organic treatment. The method of manufacturing a polymer / clay nanocomposite according to claim 8, wherein the polymer polymerization is performed in a twin screw extruder.