KR20020057645A - Organic montmorillonite and thermoplastic elastomer nanocomposites including it - Google Patents

Abstract

PURPOSE: Organic montmorillonite for manufacturing nanocomposites is provided to improve mechanical properties including tensile strength by easily reinforcing hard block of styrene based thermoplastic elastomer using organic montmorillonite. CONSTITUTION: The organic montmorillonite is obtained by cation substitution reacting montmorillonite(1) using a mixture of 5 to 70 wt.% of diammonium salt(3) selected from the group consisting of Br¬-(CH3)2¬+N(CH2)17N¬+(CH3)2Br¬-, Br¬-(CH3)2H¬+N(CH2)17N¬+H(CH3)2Br¬-, Br¬-H3¬+N(CH2)17N¬+H3Br¬- and Cl¬-H3¬+N(CH2)12N¬+H3Cl¬- and 30 to 95 wt.% of monoammonium salt(2) selected from the group consisting of (CH3(CH2)17)2N¬+(CH3)2Br¬-, (CH3(CH2)17)2HN¬+(CH3)Br¬-, (CH3(CH2)17)HN¬+(CH3)2Br¬- and (CH3(CH2)17)H2N¬+(CH3)Br¬-, wherein the diammonium salt is 1,12-dodecyl diammonium chloride, and the monoammonium salt is dodecyltrimethylammonium bromide or octadecyltrimethylammonium bromide. The thermoplastic elastomer nanocomposite is obtained by mixing 1 to 10 weight parts of the organic montmorillonite with 100 weight parts of polymer selected from the group consisting of styrene-butylene-styrene block copolymer, styrene-ethyl-butyl-styrene block copolymer and styrene-isoprene-styrene block copolymer.

Description

Organic montmorillonite and thermoplastic elastomer nanocomposites including it

The present invention relates to an organicated montmorillonite and a thermoplastic elastomer nanocomposite containing the same, and more particularly, to an organic montmorillonite prepared by mixing a diammonium salt and a monoammonium salt as an organic agent in the process of organicizing Na-montmorillonite. The present invention relates to a thermoplastic elastomer nanocomposite prepared by mixing a thermoplastic elastomer such as polystyrene-butadiene-polystyrene block copolymer.

Clay dispersing polymer nanocomposite manufacturing technology is a technique of infiltrating polymer resin through layers of clay minerals having a silicate layered structure such as montmorillonite to induce layered peeling and peeling and dispersing nanoscale silicate sheet-like basic units in the polymer resin. In addition, the polymer nanocomposite thus obtained can improve the low mechanical properties of the general-purpose polymer.

However, plate silicate, the basic unit of clay minerals, is very difficult to peel and disperse in polymer resin due to the strong attraction between the plates.

As a method for solving this problem, a method of inserting a low-molecular-weight organizing agent between silicate layered structures and organicizing them to increase the interlaminar distance of montmorillonite to facilitate the penetration of the polymer resin to peel and disperse it has been proposed. At this time, ammonium salts such as dodecyltrimethylammonium bromide and octadecyltrimethylammonium bromide are used as the low-molecular-weight organizing agent. Usually, ammonium has 12 to 18 aliphatic groups.

Montmorillonite, on the other hand, is a representative 2: 1 smectite-based layered clay with a high aspect ratio (500-1000). The interlaminar distance of montmorillonite is less than 1 nm, but the interlaminar distance varies depending on the type of cation and water content. Specifically, in the natural state, Na ⁺ or Ca ²⁺ is present between the layers as water and the interlayer distance is less than about 1 nm. If the cation substitution reaction is carried out with an organic agent such as ammonium chloride having 6 to 18 carbon atoms, Organized montmorillonite with an interlayer distance of 2-3 nm is produced.

This will be described in detail with reference to the drawings. FIG. 1 shows a plate where Na ⁺ montmorillonite is aggregated.

Treatment with ammonium salts causes cation exchange reactions with Na ⁺ , whereby ammonium salts enter the Na ⁺ sites to widen the interlayer distance, and polymers are intercalated between these broad layers to form nanocomposites (Journal of Applied Polymer Science, Vol. 67, 87-92 (1998).

The nanocomposites thus obtained can be divided into implantable and exfoliated types (see FIG. 2), wherein exfoliated nanocomposites are those which completely disperse the silicate layer in the polymer matrix, and intercalated nanocomposites are silicates. The polymer is inserted between the layers. Such nanocomposites are known to be able to further enhance strength and stiffness, gas permeability, flame resistance, wear resistance, and high temperature stability without damaging the impact resistance, toughness and transparency of the polymer resin.

In 1987, research by Japanese researchers in Japan and the United States has been actively conducted since it was reported by Toyota researchers in Japan that the separation of nylon monomers between silicate layers by an appropriate method and interlayer polymerization increased the interlaminar distance by nearly 100Å. of Polymer Science.Part B; Polymer Chemistry, Vol. 31, 1755-1758 (1993), Journal of Polymer Science.Part B; Polymer Physics, Vol. 32, 625-630 (1994)). However, this polymerization method has a number of problems, including that it can be used only when cationic polymerization is possible.

Another method for preparing a nanocomposite is a solution method. A method of preparing a nanocomposite by dissolving a polymer in a solvent to form a 5-10 wt% polymer solution and then mixing and drying the organic montmorillonite with 3-10 wt%. to be. However, the solution method requires the use of excess solvent, a separate solvent removal process, there is a problem that the polymer is simply inserted between the layers of the organic montmorillonite, or the distance between the layers is narrow again during the solvent drying process.

On the other hand, in recent years, the compounding method of dispersing the montmorillonite sheet by inserting the polymer chain in the molten state between the organic clay silicate layer, such as organic montmorillonite, and mechanically mixed it.

However, polar polymers such as nylon, polyol, polyvinyl alcohol, and epoxy resins are relatively easy to insert montmorillonite into organic layers, but nonpolar polymers such as polypropylene hardly intercalate and weakly polar polymers such as polystyrene are partially inserted. Because only this occurs, the application of polymers such as polypropylene and polystyrene to the compounding method is limited (Macromolecules, Vol. 28, 8080-8086 (1995), Journal of Materials Science Letter, Vol. 15, 1481-1483 (1996). ), Journal of Materials Science Letter, Vol. 16, 1670-1672 (1997).

In order to solve this problem, the polar polymer is introduced into the nonpolar polymer through chemical modification, so that the modified polymer can be easily intercalated between the organic montmorillonite layers, and the modified polymer is melt mixed with the organic montmorillonite. A method of making a batch and then mixing it with a polymer was introduced.

As a representative example, in 1997, Toyota, Japan, developed a polypropylene nanocomposite using a maleic anhydride-grafted propylene oligomer as a compatibilizer for organic montmorillonite and polypropylene (Journal of Appied Polymer Science, Vol. 66, 1781-1785 (1997), Macromolecules, Vol. 30, 6333-6338, (1997)).

On the other hand, many researches on the production of nanocomposites of thermoplastic elastomers have been attempted. The thermoplastic elastomer is composed of a hard block made of a rigid structure and a soft block made of a flexible molecular structure. For example, in the case of polystyrene-butadiene-polystyrene block copolymers, polystyrene blocks act as hard blocks and butadiene blocks act as soft blocks. The tensile properties of these thermoplastic elastomers are determined by the toughness of the hard blocks and the physical bonding force between the hard blocks.

If the hard block that determines the tensile properties of the thermoplastic elastomer is reinforced with organic montmorillonite, the physical properties of the thermoplastic elastomer are expected to be rapidly improved.

However, when the molecules constituting the polymer constituting the hard block of the thermoplastic elastomer are weak or nonpolar polymers, the reinforcing effect is insignificant because the attractive force between the organic montmorillonite and the polymer is not strong.

For example, in the case of styrene-butadiene-styrene, the styrene block partially inserts into the organic montmorillonite layer during the melt mixing process, but the polymer chain is easily moved during the tensile test, so the desired physical properties cannot be expected.

Thus, the present inventors while trying to manufacture a nanocomposite of the styrene-based thermoplastic elastomer composed of a molecule having a weak polarity of the hard block, to produce an organic montmorillonite treated with monoammonium salt and diammonium salt as an organic agent, As a result of nanocomposite mixing with the polymer, it was found that the mechanical properties of the thermoplastic elastomer can be improved, thereby completing the present invention.

Accordingly, an object of the present invention is to easily reinforce a hard block of a thermoplastic elastomer, in particular a hard block of a styrene-based thermoplastic elastomer composed of molecules having a weak polarity with organicized montmorillonite, and to organicize nanocomposites for improving mechanical properties such as tensile properties. To provide montmorillonite.

It is also an object of the present invention to provide a nanocomposite prepared by mixing the above-mentioned organic montmorillonite with a polymer.

The organicized montmorillonite of the present invention for achieving the above object is characterized by being obtained by cation substitution reaction of montmorillonite using a mixture of diammonium salt and monoammonium salt.

In addition, the thermoplastic elastomer nanocomposite of the present invention is characterized in that it is obtained by mixing the organicized montmorillonite and a polymer.

1 is a picture of the Na ⁺ montmorillonite plated together,

Figure 2 is a schematic diagram of manufacturing clay dispersion nanocomposites,

(a) an insertable nanocomposite and (b) a peelable nanocomposite.

3 is a schematic diagram for explaining an embodiment of the present invention.

(a) montmorillonite before melt mixing,

(b) montmorillonite during melt mixing, and

(c) Montmorillonite after melt mixing.

<Explanation of symbols for the main parts of the drawings>

1-montmorillonite 2 monoammonium salt

3 diammonium

The present invention will be described in more detail as follows.

(1) organic montmorillonite

In the present invention, the organizing agent used in the preparation of the organicized montmorillonite is a mixture of a diammonium salt and a monoammonium salt, where the diammonium salt is added to a diamine such as 1,12-dodecane diamine in distilled water and treated with an appropriate amount of hydrochloric acid. The obtained dodecane ammonium salt is mentioned as an example. Here, diamine may use all primary, secondary, tertiary and quaternary ammonium, and has a structure similar to the monoammonium salt used to prepare montmorillonite, which is commonly used, and has a flexible aliphatic group between ammonium. The length between the diammoniums is preferably at least 20 kPa (12 or more C). If the distance between the diammonium is smaller than this, it is difficult to insert between the polymerized montmorillonite layer during the melt mixing process in the nanocomposite manufacturing.

Examples of specific diammonium salts are Br^-(CH₃)₂ ⁺N (CH₂)₁₇N⁺(CH₃)₂Br^-, Br^-(CH₃)₂H⁺N (CH₂)₁₇N⁺H (CH₃)₂Br^-, Br^-H₃ ⁺N (CH₂)₁₇N⁺H₃Br^-Or Cl^-H₃ ⁺N (CH₂)₁₂N⁺H₃Cl^-Can be mentioned.

By the way, in the Example of this invention, the 1, 12- dodecanediamine which was comparatively easy to purchase was processed and used.

On the other hand, as a specific example of the monoammonium salt mixed with the diammonium salt, the monoammonium salt used in the present invention may generally use dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, or the like, which is used for preparing montmorillonite.

More specifically, (CH₃(CH₂)₁₇)₂N⁺(CH₃)₂Br^-, (CH₃(CH₂)₁₇)₂HN⁺(CH₃) Br^-, (CH₃(CH₂)₁₇) HN⁺(CH₃)₂Br^-, (CH₃(CH₂)₁₇H₂N⁺(CH₃) Br^-Etc. can be mentioned.

In the present invention, octadecyltrimethylammonium bromide was used.

In the present invention, when the montmorillonite is organicized, the above-described diammonium salt and monoammonium salt are mixed and preferably mixed with 5 to 70% by weight of diammonium salt and 30 to 95% by weight of monoammonium salt.

If the content of diammonium salt in the organic agent is less than 5% by weight, it is difficult to fix the polystyrene block due to weak mixing between layers after melt mixing. If the content is more than 70% by weight, the montmorillonite organicized during the melt mixing process is too strong. There is a difficulty in dispersing well.

As described above, the organic montmorillonite may be prepared by cationic substitution of montmorillonite according to a conventional method using an organic agent mixed with a diammonium salt and a monoammonium salt.

In general, the amount of the organic agent used is 20 to 40 parts by weight based on 100 parts by weight of montmorillonite.

An example of the manufacturing process of more specific organic montmorillonite is as follows.

First, 20 g of Na-montmorillonite is dispersed in 4 L of distilled water at 80 ° C. 7 g of the organic ammonium chloride was dissolved in 500 ml of distilled water at 80 ° C. and mixed. If left for 1 hour after stirring for 10 hours, white precipitates are formed. The white precipitate is separated by a centrifuge, washed 2-3 times with distilled water, and dried at 100 ° C. for 24 hours to obtain organic montmorillonite.

(2) thermoplastic elastomer nanocomposites

The thermoplastic elastomer nanocomposite according to the present invention can be obtained by mixing the organicated montmorillonite and the polymer obtained above.

The thermoplastic elastomer used in the present invention is a hard block made of styrene having a weak polarity, and specific examples thereof include styrene-butadiene-styrene block copolymer, styrene-ethyl-butyl-styrene block copolymer, and styrene-isoprene-styrene block copolymer. These copolymers are called thermoplastic elastomers and have similar physical properties due to the presence of styrene blocks at the end of the socks and rubber blocks at the center. On the other hand, the styrene-butadiene-styrene block copolymer can be divided into branched and linear, such a structure does not significantly affect the effect of the present invention.

It is preferable to mix the said organicized montmorillonite in 1-10 weight part with respect to 100 weight part of such thermoplastic elastomers. It is usually not particularly limited to the content generalized in the production of nanocomposites.

On the other hand, the principle of improving the physical properties of the thermoplastic elastomer by the montmorillonite organicized will be described with reference to FIG.

Figure 3 (a) is a schematic diagram of the organic montmorillonite powdered at room temperature, when the organic montmorillonite melt-mixed with a polymer (melt) because the melt mixing temperature is high temperature organizing agent of the organic montmorillonite as in (b) Molecular motion of the polymer becomes active and polymer is inserted as the interlaminar distance of organic montmorillonite increases. When the mixing is completed and cooled to room temperature, the polymer is cooled to the same state as in (c), and the molecular motion of the organicated montmorillonite organic agent is slowed, and the interlayer distance of the organic montmorillonite becomes narrower than the fusion mixed state. At this time, the montmorillonite plates organicized by the diammonium salt fix the polymer like tongs. That is, the diammonium salt acts as a spring. In this way, the montmorillonite organicized can improve the mechanical properties such as tensile properties by restricting the movement of the polymer (hard block of the thermoplastic elastomer).

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

In the following Examples and Comparative Examples, the distance between layers of the organic montmorillonite is increased according to the degree of insertion of the polymer between the layers of the organic montmorillonite, so that the interlayer distance is mixed with the XRD after mixing the polymer and the organic montmorillonite to know the degree of intercalation. The change of was measured. The measurement sample was made of 0.3 mm thick film and measured. The measurement speed was 2 ° per minute and the measurement angle was measured in the range of 1-10 °.

Tensile test was carried out by ASTM D-425 method, the sample was pressed for 10 minutes by hot press, and then made a plate of 3mm thickness, and made a tensile specimen with JIS K6301 specimen cutter, and the cross head speed was 500mm / min.

The examples and comparative examples described herein are for illustrative purposes only and are not intended to limit the scope of the present invention.

Preparation Example 1 Preparation of Organized Montmorillonite

20 g of Na-montmorillonite was dispersed in 4 L of distilled water at 80 ° C. 7 g of dodecane diammonium chloride was dissolved in 500 ml of distilled water at 80 ° C., followed by mixing. After stirring for 10 hours, the mixture was left for 1 hour to generate a white precipitate. The obtained white precipitate was separated by a centrifuge, washed 2-3 times with distilled water, and dried at 100 ° C. for 24 hours to prepare organic montmorillonite.

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Preparation Example 2 Preparation of Organized Montmorillonite

Organically prepared montmorillonite was prepared in the same manner as in Preparation Example 1, except that 7 g of octadecyltrimethylammonium bromide was used instead of using dodecanediammonium chloride as an organic agent.

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Preparation Example 1 Preparation of Organicated Montmorillonite

Organically prepared montmorillonite was prepared in the same manner as in Preparation Example 1, except that 2.1 g of octadecyltrimethylammonium bromide and 4.9 g of dodecanediammonium chloride (3: 7 weight ratio) were used as an organic agent.

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Preparation Example 2 Preparation of Organicated Montmorillonite

Organically prepared montmorillonite was prepared in the same manner as in Preparation Example 1, except that 3.5 g of octadecyltrimethylammonium bromide and 3.5 g of dodecanediammonium chloride were used as an organic agent (5: 5 weight ratio).

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Preparation Example 3 Preparation of Organized Montmorillonite

Organically prepared montmorillonite was prepared in the same manner as in Preparation Example 1, except that 4.9 g of octadecyltrimethylammonium bromide and 2.1 g (7: 3 weight ratio) of dodecanediammonium chloride were used as an organic agent.

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Preparation Example 4 Preparation of Organicated Montmorillonite

Organically prepared montmorillonite was prepared in the same manner as in Preparation Example 1, except that 6.3 g of octadecyltrimethylammonium bromide and 0.7 g of dodecanediammonium chloride were used as an organic agent (9: 1 weight ratio).

The interlaminar distances of the obtained montmorillonite are shown in Table 1 below.

Production Example Comparative Example One 2 3 4 One 2 Dodecanediammonium chloride (wt%) 70 50 30 10 100 0 Octadecyltrimethylammonium bromide (wt%) 30 50 70 90 0 100 Interlayer Distance Å 20.0 22.4 26.3 28.3 16.0 33

Example 1 Preparation of Nanocomposites

To 5 parts by weight of the organicized montmorillonite prepared in Preparation Example 1 with respect to 100 parts by weight of styrene-butadiene-styrene block copolymer was mixed in a banbari mixer for 10 minutes at 150 ℃ Then, the sample was prepared by pressing for 10 minutes using a hot press at 150 ℃ conditions.

The tensile strength of the sample thus prepared was measured by a tensile tester, and the change in the interlayer distance of the montmorillonite in the sample was measured by XRD, and the results are shown in Table 2 below.

Example 2: Preparation of Nanocomposites

5 parts by weight of the organicated montmorillonite prepared in Preparation Example 2 with respect to 100 parts by weight of styrene-butadiene-styrene block copolymer was placed in a banbari mixer and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Example 3: Preparation of Nanocomposites

5 parts by weight of the organicized montmorillonite prepared in Preparation Example 3 with respect to 100 parts by weight of the styrene-butadiene-styrene block copolymer was put in a Bambari mixer and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Example 4: Preparation of Nanocomposites

5 parts by weight of the organicated montmorillonite prepared in Preparation Example 4 based on 100 parts by weight of styrene-butadiene-styrene block copolymer was placed in a chestnut mixer and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 1: Preparation of Nanocomposites

5 parts by weight of the organicized montmorillonite prepared in Preparation Example 1 based on 100 parts by weight of styrene-butadiene-styrene block copolymer was put in a chestnut mixer and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 2: Preparation of Nanocomposites

5 parts by weight of the organicized montmorillonite prepared in Comparative Preparation Example 2 with respect to 100 parts by weight of styrene-butadiene-styrene block copolymer was put in a chestnut mixer, and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Comparative Example 3: Preparation of Thermoplastic Elastomers

Styrene-butadiene-styrene block copolymer was placed in a Bambari mixer and the specimens were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

Example Comparative example One 2 3 4 One 2 3 Interlayer Distance (Å) 21.0 25.3 28.3 31.0 16.0 36.0 - Tensile strength (kgf / cm ² ) 210 230 245 270 200 210 210 300% modulus (kgf / cm ² ) 34 35 37 38 34 37 31

From the results of Table 2, in the case of a nanocomposite using an organicized montmorillonite prepared by mixing a diammonium salt and a monoammonium salt as in the embodiment of the present invention, the monoammonium salt was used in the melt mixing process to widen the interlayer distance of the organicized montmorillonite. It can be seen that the insertion of the polymer and the diammonium salt serve to limit the movement of the hard block of the polymer after melt mixing is completed, thereby improving the tensile properties of the thermoplastic elastomer.

On the other hand, when only the diammonium salt is used, the interlayer attraction is strengthened and the interlayer distance is not so wide that the polymer is more difficult to insert into the layer than the monoammonium salt alone. It can be seen that the polymer can be easily moved during the experiment, so that the improvement of tensile properties cannot be expected.

As described in detail above, nanocomposites prepared by mixing montmorillonite using a mixture of diammonium salts and monoammonium salts according to the present invention and mixing them with a polymer are generally hard in styrene-based thermoplastic elastomers in which hard blocks are made of weakly polar molecules. Easily reinforcing the block can improve the tensile properties of the thermoplastic elastomer in the form of a block copolymer, and furthermore, the homopolymer is expected to improve the physical properties in the same principle.

Claims (9)

Organicized montmorillonite obtained by cationic substitution reaction of montmorillonite using a mixture of diammonium salt and monoammonium salt. The organicated montmorillonite according to claim 1, wherein 5 to 70% by weight of the diammonium salt and 30 to 95% by weight of the monoammonium salt are mixed. The method of claim 1 wherein the diammonium salt is Br^-(CH₃)₂ ⁺N (CH₂)₁₇N⁺(CH₃)₂Br^-, Br^-(CH₃)₂H⁺N (CH₂)₁₇N⁺H (CH₃)₂Br^-, Br^-H₃ ⁺N (CH₂)₁₇N⁺H₃Br^-And Cl^-H₃ ⁺N (CH₂)₁₂N⁺H₃Cl^-Organic montmorillonite, characterized in that selected from the group consisting of. The organotized montmorillonite of claim 1, wherein the diammonium salt is 1,12-dodecyldiammonium chloride. The monoammonium salt of claim 1, wherein₃(CH₂)₁₇)₂N⁺(CH₃)₂Br^-, (CH₃(CH₂)₁₇)₂HN⁺(CH₃) Br^-, (CH₃(CH₂)₁₇) HN⁺(CH₃)₂Br^-And (CH₃(CH₂)₁₇H₂N⁺(CH₃) Br^-Organic montmorillonite, characterized in that selected from the group consisting of. The organotylated montmorillonite of claim 1, wherein the monoammonium salt is dodecyltrimethylammonium bromide or octadecyltrimethylammonium bromide. A thermoplastic elastomer nanocomposite obtained by mixing the organicized montmorillonite of claim 1 with a polymer. 8. The thermoplastic elastomer nano of claim 7 wherein the polymer is selected from the group consisting of styrene-butylene-styrene block copolymers, styrene-ethyl-butyl-styrene block copolymers and styrene-isoprene-styrene block copolymers. Composites. 8. The thermoplastic elastomer nanocomposite according to claim 7, wherein the organic montmorillonite is mixed in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer.