KR20030017216A - Method to prepare nanocomposites of thermoplastic elastomers - Google Patents

Abstract

PURPOSE: Provided is a method for preparing polymeric nanocomposites of thermoplastic elastomer by using styrene-based block copolymer having a terminal group substituted by a functional group which is easy in intercalation and enhances the mechanical physical property. CONSTITUTION: The polymeric nanocomposites of thermoplastic elastomer are prepared by melt-mixing a polymer resin and a montmorillonite by a compounding method. The method is characterized in that the styrene-based block copolymer having the terminal group modified with amines is used as the polymer resin. The amines are pyrrolidone or piperidine. The styrene-based block copolymer is styrene-butadiene-styrene block copolymer, styrene-ethyl-butyl-styrene block copolymer or styrene-isoprene-styrene block copolymer.

Description

Method for preparing nanocomposites of thermoplastic elastomers {Method to prepare nanocomposites of thermoplastic elastomers}

The present invention relates to a method for producing a nanocomposite of a thermoplastic elastomer, and more particularly, a polymer prepared by mixing a styrene-based copolymer substituted with a functional group such as an amine with an improved polarity and organicized montmorillonite by a compounding method. It relates to a nanocomposite.

Clay dispersing polymer nanocomposite production technology is a technique in which the polymer resin penetrates between layers of clay minerals such as montmorillonite having a silicate layer structure, causing peeling of the layered structure, and peeling and dispersing the nanoscale plate silicate into the polymer resin.

In general, nanocomposites can be divided into insert type and exfoliation type. Exfoliated nanocomposites are those in which the silicate layer is completely dispersed in the polymer matrix, and intercalated nanocomposites are polymers inserted between the silicate layers. It is a form.

On the other hand, montmorillonite, a representative clay mineral, is a representative 2: 1 smectite-based layered clay having a high aspect ratio (500 to 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, and the cation substitution reaction is performed with an organic agent such as ammonium chloride having 6 to 18 carbon atoms. This yields an organic montmorillonite having an interlayer distance of 2-3 nm.

This will be described in detail with reference to the drawings. FIG. 1 shows a plate where Na ⁺ montmorillonite is aggregated. The polymer is inserted between the widened layers to form a nanocomposite (Journal of Applied Polymer Science, Vol. 67, 87-92 (1998)).

Such nanocomposites are known to increase the strength and stiffness, gas permeability, flame resistance, abrasion resistance, and high temperature stability without damaging the impact resistance, toughness and transparency of the polymer resin.

In 1987, Japanese researchers in Japan and the United States have been actively researching since the peeling phenomenon of increasing the distance between layers by inserting nylon monomers between silicate layers and polymerizing them in an appropriate manner was reported. 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 problems such as can be used only when cationic polymerization is possible.

The polymer nanocomposite prepared by the above method has the advantage of improving the low mechanical properties of the general-purpose polymer, while the plate silicate, which is the basic unit of the clay mineral, is separated from the polymer resin due to the strong attraction between the plate and the plate. Very difficult to disperse

In order to solve this problem, a polymer organic agent substituted with a functional group having improved polarity at the polymer terminal or the main chain is inserted into the organic silicate layered structure to be organicized and then peeled and dispersed by facilitating the penetration of the polymer resin. There is this.

On the other hand, another method for producing a nanocomposite is a solution method, the polymer is dissolved in a solvent to make a 5-10 wt% polymer solution, and then mixed and dried with 3-10 wt% of the organic montmorillonite nano It is a method of manufacturing a composite material.

However, the solution method has the problem of using an excess of solvent, a separate solvent removal process, and the polymer is simply inserted between the layers of montmorillonite organicized 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, resulting in nonpolar polymers or weak polar polymers (polypropylene). , Polystyrene) has limitations in the compounding method (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 was introduced into the nonpolar polymer through chemical modification, so that the modified polymer was easily inserted between the organic montmorillonite layers, and the modified polymer was melt mixed with the organic montmorillonite to form a master batch. , A method of mixing 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 Applied Polymer Science, Vol. 66 , 1781-1785 (1997), Macromolecules, Vol. 30, 6333-6338, (1997)).

However, this method increased the amount of polypropylene intercalated between the organicized montmorillonite layers, but did not improve the mechanical properties of the polypropylene. Accordingly, there is a demand for the development of nanocomposites that can easily intercalate and improve mechanical properties.

Thus, the present inventors while trying to solve the problem of manufacturing a styrene-based nanocomposite composed of a weak polar polymer as described above, replacing the terminal of the conventional styrene-based block copolymer with the functional group of the amine polarity improved As a result of preparing a thermoplastic elastomeric polymer nanocomposite by mixing the styrene-based block copolymer and the organicized montmorillonite by the compounding method, it was found that the interlayer insertion is easy and the mechanical properties are improved without deterioration of transparency. Was done.

Accordingly, an object of the present invention is to provide a method for producing a thermoplastic elastomeric polymer nanocomposite using a styrenic block copolymer substituted with a functional group having improved polarity, which facilitates intercalation and improves mechanical properties. have.

The above and other objects of the present invention will become apparent from the construction and operation of the following invention.

Method for producing a polymer nanocomposite of the thermoplastic elastomer of the present invention for achieving the above object is a method of melt-mixing a polymer resin and organicized montmorillonite by a compounding method, wherein the end of the polymer resin is modified with amines It is characterized by using a styrenic block copolymer.

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.

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

Styrene-based block copolymers whose terminals are substituted with functional groups with improved polarity

The styrenic block copolymer for thermoplastic elastomer polymer nanocomposite of the present invention has a form in which a terminal is substituted with an amine functional group such as pyrrolidone or piperidine. The styrenic block copolymer in which the terminal is substituted with amines is obtained by polymerizing using an amine having a functional group to modify the anionic polymerization initiator used in the polymerization of the styrenic block copolymer.

The number-average molecular weight of the end-modified styrene-based block copolymer thus prepared is in the range of 80,000 to 100,000.

On the other hand, styrene-based block copolymers that can be used in the present invention include styrene-butadiene-styrene block copolymers, styrene-ethyl-butyl-styrene block copolymers, and styrene-isoprene-styrene block copolymers.

The copolymers are thermoplastic elastomers, in which both ends of the copolymer are styrene blocks and rubber blocks are present in the middle thereof, and the physical properties of the copolymers are similar.

Meanwhile, in Examples and Comparative Examples of the present invention, styrene-butadiene-styrene block copolymer (SBS), which is most used among styrene block copolymers, was used.

Thermoplastic Elastomer Polymer Nanocomposites

The thermoplastic elastomer polymer nanocomposite can be prepared by mixing the styrene-based block copolymer substituted with a terminal having an improved polarity of the amine-based prepared with a conventional organic montmorillonite, in particular, the organic montmorillonite is a kind of It is not limited, in Examples and Comparative Examples of the present invention used Cloistite 6A of Southern Clay Product of the United States.

Cloisite 6A is an organic treatment of Na-montmorillonite with dimethyl dihydrogenated tallow amminium, with varying degrees of organication. Cloisite 6A has an interlayer distance of 34.60 Å and an organic concentration of 140 meq / 100g.

In the preparation of the thermoplastic elastomeric polymer nanocomposite, the amount of the montmorillonite organicated is 3 to 10 parts by weight based on 100 parts by weight of the styrenic block copolymer.

If the amount is less than the above range, it may not play a role as a reinforcing material, and if it exceeds the above range, it may not be expected to improve physical properties due to additional input, and the transparency may be lowered to 3 to 10 parts by weight. It is preferable.

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

Preparation Example 1 Preparation of Styrene-Based Block Copolymer Substituted with Pyrrolidone

First, the initiator solution is synthesized and then subjected to polymerization. The synthesis of the initiator is carried out by arranging 40 ml of cyclohexane, 20 ml of normal butyllithium (2 mol cyclohexane solution), and 6.5 ml of dried tetrahydrofuran in an argon atmosphere. Was added. After the solution was stirred for 10 minutes, 2.0 ml of pyrrolidine was added and stirred for another 2 hours to obtain an initiator solution.

The polymerization reaction in which the terminal is substituted with pyrrolidone is performed by adding 960 g of cyclohexane, 0.26 g of tetramethylethylenediamine (N, N, N ', N'-tetramethylethylenediamine) and 48 g of styrene, which are dried in a 2 L pressure reactor in an argon gas atmosphere. It was. The solution was heated to 60 ° C., and then the initiator solution prepared above was added to initiate polymerization to react for 60 minutes. 112 g of butadiene was added thereto to initiate the second polymerization. After 40 minutes, 4 g of dichlorodimethylsilane was added thereto and reacted for 60 minutes. Finally, a small amount of methanol was added to terminate the reaction. Thereafter, the polymer crumb was obtained by desolventing with steam and dried using a roll mixer.

The number average molecular weight was 102,320 g / ml as a result of measuring the molecular weight of the styrene block copolymer in which the terminal obtained above was substituted by pyrrolidone through gel permeation chromatography (GPC).

Preparation Example 2 Preparation of Styrene-Based Block Copolymer Substituted with Piperidine

Except for using piperidine instead of pyrrolidine, it was prepared in the same manner as in Preparation Example 1, and the number-average molecular weight of the prepared styrene block copolymer substituted with piperidine was 96,480 g / ml. .

(Example 1)

3 parts by weight of montmorillonite organicated with respect to 100 parts by weight of the styrene-butadiene-styrene (SBS) block copolymer end-modified with pyrrolidone prepared in Preparation Example 1 were mixed in a Banbari mixer for 10 minutes at 130 ° C. Thereafter, the sample was prepared by compressing the mixture for 10 minutes using a hot press at 150 ° C.

The change in transparency, tensile strength, and interlaminar distance of the montmorillonite of the prepared montmorillonite was measured by the following test method, and the results are shown in Table 1 below.

Transparency Measurement

In order to measure the transparency of the samples obtained in the Examples and Comparative Examples of the present invention, the transmittance at 425 nm was measured using an ultraviolet spectrometer after making a 0.3 mm thick film.

Tensile Strength Measurement

Tensile strength was measured according to the ASTM D-425 method to confirm the mechanical properties. After compressing the samples prepared in Examples and Comparative Examples of the present invention by a hot press (Hot press) for 10 minutes, and then made a plate of 3mm thickness, after making a tensile specimen with a JIS K6301 specimen cutter and cross head Tensile strength was measured at a speed of 500 mm / min.

D-spacing measurement

In addition, the nanocomposites prepared in the Examples and Comparative Examples of the present invention are organicized with the polymer to confirm the degree of intercalation, since the interlayer distance of the montmorillonite organicated is changed according to the degree of insertion of the polymer between the layers of the montmorillonite organicated. After the montmorillonite was mixed, the change of the interlayer distance was measured by an X-ray diffraction apparatus (XRD). After the measurement sample was made into a 0.3 mm thick film, it was measured at a measurement angle range of 2θ1 to 10 ° at a speed of 2 ° per minute.

(Example 2)

5 parts by weight of montmorillonite organicated with respect to 100 parts by weight of the SBS block copolymer modified with pyrrolidone prepared in Preparation Example 1 were placed in a banbari mixer and mixed at 130 ° C. for 10 minutes. Thereafter, the sample was prepared by compressing the mixture for 10 minutes using a hot press at 150 ° C.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

(Example 3)

10 parts by weight of the montmorillonite organicated with respect to 100 parts by weight of the SBS block copolymer modified with pyrrolidone prepared in Preparation Example 1 was placed in a banbari mixer and mixed at 130 ° C. for 10 minutes. Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

(Example 4)

To 5 parts by weight of the montmorillonite organicated with respect to 100 parts by weight of the SBS block copolymer modified with piperidine obtained in Preparation Example 2 in a Banbari mixer and mixed for 10 minutes at 130 ℃ Thereafter, the sample was prepared by compressing the mixture for 10 minutes using a hot press at 150 ° C.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

Example One 2 3 4 Resin composition (part by weight) Terminal Modified SBS 100 100 100 100 O-MMT 3 5 10 5 Interlayer Distance (Å) 36.5 37.9 38.6 37.2 Tensile strength (kgf / cm ² ) 221 242 255 237 300% modulus (kgf / cm ² ) 35 41 45 40 Transmittance (%) 80 78 76 78 SBS: Styrene-Butadiene-Styrene block copolymer O-MMT: Organized montmorillonite Cloisite 6A: Interlayer distance 34.60 Å, Organic concentration 140meq / 100g

(Comparative Example 1)

100 parts by weight of a conventional SBS block copolymer was placed in a half-barrier mixer and stirred at 130 ° C. for 10 minutes. Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

(Comparative Example 2)

To 3 parts by weight of the organic montmorillonite with respect to 100 parts by weight of conventional SBS block copolymer in a half-barrier mixer and mixed for 10 minutes at 130 ℃ Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

(Comparative Example 3)

To 5 parts by weight of the organic montmorillonite with respect to 100 parts by weight of conventional SBS was put in a half-barrier mixer and mixed for 10 minutes at 130 ℃ Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

(Comparative Example 4)

5 parts by weight of low molecular weight polystyrene was added to a half-barrier mixer and mixed at 130 ° C. for 10 minutes based on 100 parts by weight of conventional SBS block copolymer. Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

(Comparative Example 5)

10 parts by weight of low molecular weight polystyrene with 100 parts by weight of conventional SBS block copolymer was placed in a half-barrier mixer and mixed at 130 ° C. for 10 minutes. Then, the sample was prepared by compressing for 10 minutes using a hot press at 150 ° C conditions.

The transparency, tensile strength, and interlayer distance change of the samples thus prepared were measured in the same manner as in Example 1, and the results are shown in Table 2 below.

Comparative example One 2 3 4 5 Resin composition (part by weight) SBS 100 100 100 100 100 O-MMT 0 3 5 0 0 PS 0 0 0 5 10 Interlayer distance - 35.2 35.6 35.7 35.7 Tensile strength (kgf / cm ² ) 210 215 220 222 222 300% modulus (kgf / cm ² ) 33 35 40 41 41 Transmittance (%) 82 77 75 77 77 SBS: Styrene-Butadiene-Styrene block copolymer PS: Polystyrene O-MMT: Organicized montmorillonite Cloisite 6A: Interlayer distance 34.60 Å, Organic concentration 140meq / 100g

As described in detail above, when simply mixed with organic montmorillonite and SBS, the tensile strength does not change significantly, it was confirmed that there is no significant difference in the pure SBS and physical properties.

In addition, even if the added amount of the organicized montmorillonite up to 10 parts by weight, there was no significant improvement in physical properties such as tensile strength.

However, as a result of using the SBS in which the non-polar SBS block copolymer is modified with an amine-based functional group as in the present invention, not only the physical properties such as tensile strength and modulus are increased, but also the transparency is not reduced, and the interlayer distance is increased. Could.

In order to reliably confirm the effects of the present invention, when comparing Example 1 and Comparative Example 2, Example 2 (or Example 4) and Comparative Example 3, or Example 3 and Comparative Example 4 made of the same composition ratio, the present invention It was found that the transmittance and tensile strength of the nanocomposite prepared in

Claims (4)

In manufacturing a polymer nanocomposite by melt-mixing a polymer resin and organicized montmorillonite by a compounding method, The polymer resin is a nanocomposite manufacturing method of the thermoplastic elastomer, characterized in that the terminal using a styrene-based block copolymer modified with amines. The method of claim 1, wherein the amines are pyrrolidone or piperidine. The styrene block copolymer according to claim 1, wherein the styrene block copolymer is a styrene-butadiene-styrene block copolymer, a styrene-ethyl-butyl-styrene block copolymer, and a styrene-isoprene-styrene block copolymer. coalescence. A polymer nanocomposite obtained according to the method of claim 1.