KR20020015406A - Nanocomposite Material Comprising Crystalline Polystyrene And Organophilic Clay and Method for Preparing Thereof - Google Patents

Abstract

PURPOSE: Provided are nano composite material containing crystalline polystyrene-organic mud and its preparation method. In the nano composite material, organic mud layer is dispersed as inserted or detached structure in nano scale in the crystalline polystyrene, so that the material has excellent mechanical properties such as bending strength and tensile strength. CONSTITUTION: The composite material comprises: making a composite material by introducing amorphous styrene polymer and organic clay in a weight ratio of 1:1-20:1 into a batch mixer or an extruder and melt-mixing at the higher temperature than the transition temperature of the above amorphous styrene polymer; and melt mixing the above composite material and the crystalline polystyrene in a weight ratio of 1:1-20:1 at the higher temperature than the melting temperature(250deg.C) of the above crystalline polystyrene. The composite material is also made by melt mixing crystalline polystyrene, 5-30wt.% of amorphous styrene polymer and 1-30wt.% of organic clay at the higher temperature than the melting temperature of the above crystalline polystyrene in a batch mixer or in an extruder. The above crystalline polystyrene is styrene-based polymer with tacticity and is selected from isotactic polystyrene and syndiotactic polystyrene-based polymers and copolymers. The above amorphous styrene polymer is selected from atactic polystyrene or styrene-based block copolymers which has compatibility with the above crystalline polystyrene and builds the inserted or separated structure with the above organic clay. The above organic clay is a silicate salt of minerals substituted by alkylammonium or alkylphosphonium ion wherein it has 2:1 layer structure and is selected from montmorillonite, hectorite and saponite.

Description

Nanocomposite Material Comprising Crystalline Polystyrene And Organophilic Clay and Method for Preparing Thereof}

Field of invention

The present invention relates to a nanocomposite material consisting of crystalline polystyrene, amorphous styrene-based polymer and organic clay, and a method for producing the same. More specifically, the present invention relates to a nanocomposite material in which organic clay having a layered structure in a crystalline polystyrene is dispersed on a nano scale, and a method of manufacturing the same. More specifically, the present invention provides a polymer in the layered structure of organic clay by melt-kneading at the same time or stepwise melting and crystalline polystyrene, layered organic clay and various types of amorphous styrene-based polymer at the processing temperature of 250 ℃ or more by melt insertion method The present invention relates to a nanocomposite material dispersed in crystalline polystyrene in a form in which an interlayer gap of organic clay is formed or organic clay is separated, and a method of manufacturing the same.

Background of the Invention

Polymer composite materials have been widely used in many fields such as building materials, consumer goods, automobiles, electronic parts, etc. as materials having improved high stiffness, permeability, flame resistance, and numerical safety by adding an inorganic reinforcing agent to the polymer matrix. In particular, nanocomposites having a nanoscale dispersion of a polymer and an inorganic reinforcing agent have a higher contact area per unit volume than conventional composite materials, and thus excellent physical properties can be obtained even by adding a small amount of inorganic materials. Most of the inorganic reinforcing agent is a layered clay mineral is used has an advantage in recycling. The clay minerals include montmorillonite, hectorite, etc., which are composed of 2: 1 layered silicates, and because they have an interlayer spacing, the polymer material is inserted into the nanoscale hybrid. It can be achieved. In this case, in order to easily penetrate the polymer material into the layered structure of the clay mineral, an organic clay obtained by organically treating the clay mineral is generally used. Until now, various types of polymer resins have been produced in which nanocomposites are reinforced with organic clay having a layered structure. For the first time on a commercial scale, nylon nanocomposites were successfully manufactured by Toyota, Japan, by in-situ polymerization, and Usuki et al., US Pat. No. 4,889,885, showed excellent stiffness even when small amounts of organic clay were added. And gas barrier properties have been shown. As a manufacturing method by the polymerization method, a nanocomposite material to which polyethylene terephthalate, polycaprolactone, polyimide, epoxy, etc., in addition to nylon has been reported. Recently, a melt insertion method that can be manufactured in a conventional polymer processing apparatus has been studied, and a study on nanocomposites composed of polymers such as amorphous polystyrene and polypropylene and organic clay having a layered structure has been reported. A research group based on EP Gianellis of Cornell University, USA, discloses that nanocomposites are formed by inserting amorphous polystyrene into the layered structure of organic clay at temperatures above the glass transition temperature (RA Vaia et al., Chem. Mater. Vol 5, p 1694, 1993). Similarly, Toyota, Japan, reported a method for preparing nanocomposites composed of polypropylene and organic clay by melt insertion (M. Kawasumi et al., Macomolecules, Vol 30, p6333, 1997).

Until now, most of the polymers used in the nanocomposites manufactured by the melt insertion method have been applied at a processing temperature of about 200 ° C., and there are no examples of engineering plastics requiring higher processing temperatures and heat resistance. Organics such as substituted alkyl ammonium in the organic clay deteriorate at a temperature of 250 ° C. or higher, thereby lowering the affinity between the polymer and the organic clay, making it difficult for the polymer to penetrate into the layered structure of the organic clay. In addition, the polymer is more difficult to penetrate into the layered structure because at high temperature, the layered structure of the organic clay tends to collapse and the interlayer spacing tends to decrease.

Among these polymers, crystalline polystyrene has a melting point of about 250 ° C. to 270 ° C. according to stereoregularity. Syndiotactic polystyrene (sPS), in particular, was developed in 1980 by Idemitsu, Japan, and is emerging as a new engineering plastic due to its excellent heat resistance, rigidity and low dielectric properties. In the case of the resin, like other heat resistant engineering plastic materials, many applications have been made for electronic parts that are filled with glass fibers and require heat resistance and rigidity. However, the excessive filling of the glass fiber is not only difficult in processing, but also lowers the interfacial adhesion between the polymer and the filler, and thus lowers mechanical properties.

On the other hand, nanocomposite materials using clay minerals can be added to a small amount of organic clay and dispersed in nanoscale to make the product lighter and improve mechanical properties such as rigidity and strength. However, the preparation of nanocomposites in which organic clays are dispersed in crystalline polystyrene at a nanoscale has not been reported due to the problem of deterioration of interlayers and deterioration of organic clays at temperatures above the melting point of crystalline polystyrene as described above. .

Accordingly, the present invention can be manufactured in an extruder or a batch mixer, which is a conventional polymer processing equipment, and nanocomposites having a layered structure are dispersed on crystalline polystyrene in a crystalline polystyrene by melt insertion method, thereby improving mechanical properties. It has begun to develop materials and methods for their preparation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a nanocomposite material having improved mechanical properties such as tensile strength and flexural rigidity by dispersing organic clay in nanoscale in crystalline polystyrene having stereoregularity.

Another object of the present invention is to melt or kneaded crystalline polystyrene, layered organic clay, and amorphous styrene-based polymers simultaneously or stepwise at a processing temperature of 250 ° C. or higher by melting inserting, so that the interlayer spacing of the organic clay is opened or separated. The present invention provides a method for preparing a nanocomposite material having improved mechanical properties by dispersing organic clay in nano form in a polystyrene.

Still another object of the present invention is to provide a method for producing a nanocomposite material which can be manufactured in an extruder or a batch mixer which is a conventional polymer processing machine.

The above and other objects of the present invention can be achieved by the present invention described below. Hereinafter, the content of the present invention will be described in detail.

FIG. 1 schematically illustrates the procedure for preparing a nanocomposite of crystalline polystyrene by a step kneading method according to the present invention.

2 is a schematic diagram illustrating the procedure of preparing a nanocomposite material of crystalline polystyrene by the co-kneading method according to the present invention.

FIG. 3 shows each X-ray for nanocomposites of crystalline polystyrene prepared by the step kneading method of Southern Clay Co. product 15A, Examples 1, 4 and 7 The results of diffraction analysis are shown.

4 shows the results of the respective X-ray diffraction analysis of the nanocomposite material of crystalline polystyrene prepared by the co-kneading method by Southern Clay's product 15A, Examples 3, 6 and 9, respectively.

Nanocomposite material of the present invention is composed of crystalline polystyrene, amorphous styrene-based polymer and organic clay having a melting temperature of 250 ℃ or more, stepwise kneading method or simultaneous kneading method by melt insertion method above the melting temperature of the crystalline polystyrene Is prepared.

Hereinafter, the components constituting the nanocomposite of the present invention and a method of preparing the same will be described in detail below.

(A) crystalline polystyrene

Crystalline polystyrene used in the nanocomposite of the present invention is used as a matrix of the nanocomposite. The crystalline polystyrene has stereoregularity and a melting point of 250 ° C. or more. Preferred embodiments are isotactic polystyrene (iPS), syndiotactic polystyrene (sPS), syndiotactic polymethylstyrene, syndiotactic polyethylstyrene, syndiotactic polyisopropylstyrene as derivatives thereof , Syndiotactic polybutyl styrene, syndiotactic polyvinylstyrene, syndiotactic polychlorostyrene, syndiotactic polybromostyrene or syndiotactic polyfluorostyrene, syndiotactic styrene-isoprene aerial Polystyrene-co-isoprene, syndiotactic styrene-vinylnaphthalene, and the like.

(B) Amorphous Styrenic Polymer

The amorphous styrene-based polymer used in the nanocomposite of the present invention is a polymer having a glass transition temperature of about 100 ° C., which is inserted into the layered structure of the organic clay in a molten state to enable the formation of the nanocomposite.

Specific examples of the amorphous styrene-based polymer include atactic polystyrene (aPS), styrene-maleic anhydride copolymer (SMA) copolymer or oxazoline polystyrene (OPS) as a derivative thereof. Styrene-butadiene block copolymers (SB), styrene-butadiene-styrene block copolymers (SBS), styrene, a block copolymer series of styrene and ethylene or butylene Ethylene-butylene-styrene block copolymer (SEBS), maleic anhydride grafted styrene-ethylene-butylene (maleic anhydride grafted styrene-ethylene-butylene) -styrene block copolymer; SEBS-MA).

Since these amorphous styrene polymers have a very active behavior at the melting temperature of the crystalline polystyrene, they easily penetrate into the layered structure of the organic clay to increase or remove the interlayer spacing of the organic clay. In addition, the amorphous styrene-based polymer and crystalline polystyrene have some compatibility so that the clay layers can be dispersed in the crystalline polystyrene.

(C) organoclay

The glass clay used in the nanocomposite of the present invention has a layered structure. The organoclay is a 2: 1 silicate mineral having two tetrahedral layers composed of silicon (Si) and oxygen and one octahedral layer to form a single layer, including montmorillonite, Hectorite and saponite. In order to increase the affinity between the polymer and the clay, the inside of the layer is substituted with an organic agent of alkylammonium or alkylphosphonium.

Preparation of Nanocomposite Materials

The nanocomposite of the present invention can be produced by a step kneading method or a simultaneous kneading method.

The step kneading method (1) melt kneading the amorphous styrene-based polymer and the organic clay at a temperature of about 200 ℃ to prepare a composite material of the form in which the amorphous styrene-based polymer is penetrated into the clay layer, and (2) The composite material and the crystalline polystyrene is melt kneaded at a temperature of about 280 ℃ to produce a nanocomposite material. In the composite material of the amorphous styrene-based polymer prepared in the step (1), the composition of the organic clay is adjusted in the range of 5 to 50% by weight so that the weight ratio of the amorphous styrene-based polymer and the organic clay is 1: 1 to 1:20. It has a range of and becomes a kind of masterbatch. When melt kneading the masterbatch and crystalline polystyrene in the step (2), the composition of the masterbatch is adjusted in the range of 5 to 50% by weight depending on the content of the organic clay, so that the weight ratio of crystalline polystyrene and the composite material is 1 : 1 to 20: 1. At this time, the organic clay existing in the masterbatch maintains a layered structure that is opened or peeled even under kneading conditions of 280 ° C. because a polymer is inserted into the interlayer. In the step kneading method, the clay layer is opened or separated by an amorphous styrene-based polymer, and then maintains the opened or peeled layer structure without collapse by hot heat even when melt kneading with crystalline polystyrene. FIG. 1 schematically illustrates the procedure for preparing the nanocomposite material of the crystalline polystyrene of the present invention having such a structure by a step kneading method.

The simultaneous kneading method is a method of melt kneading crystalline polystyrene, amorphous styrene-based polymer and organic clay at a temperature of about 280 ℃ at the same time. The composition of the amorphous styrene-based polymer is adjusted in the range of 5 to 30% by weight, and the composition of the organic clay is adjusted in the range of 1 to 30% by weight. Since the amorphous styrene-based polymer has very active behavior when melt kneading at a temperature of 280 ° C., the amorphous styrene-based polymer first penetrates into the clay and inserts or peels off the layer. The cracked or exfoliated clay is dispersed in crystalline polystyrene to form a nanocomposite material. In the simultaneous kneading method, since the amorphous styrene-based polymer has an active behavior at a high temperature, it is inserted into the interlayers before the collapse of the layer structure to open or separate the layers. FIG. 2 schematically illustrates the procedure for producing a nanocomposite material of crystalline polystyrene of the present invention having such a structure by a co-kneading method.

The present invention will be further illustrated by the following examples, which are only specific examples of the present invention and are not intended to limit or limit the protection scope of the present invention.

Example

Specifications of (A) crystalline polystyrene, (B) amorphous styrene-based polymer and (C) organoclay used in the nanocomposite of the embodiment of the present invention are as follows:

(A) crystalline polystyrene

As crystalline polystyrene, syndiotactic polystyrene (sPS) was used in all examples. The clay layer structure in crystalline polystyrene was observed by X-ray diffraction analyzer and transmission electron microscope.

(B) Amorphous Styrenic Polymer

As the amorphous styrene polymer, atactic polystyrene (aPS), styrene-maleic anhydride (SMA) copolymer, and styrene-ethylene-butylene-styrene block copolymer (SEBS-MA) grafted with maleic anhydride were used.

(C) organoclay

Organoclay used 15A product of Southern clay of USA. The inside of the clay layer of the organic clay is substituted with dimethyl dihydrogenated tallow alkyl ammonium, the hydrogenated tallow has a composition of C ₁₈ : C ₁₆ : C ₁₄ = 65%: 30%: 5%.

Table 1 shows the constituents and compositions of the nanocomposites used in each of the examples.

division (A) crystalline polystyrene (B) Amorphous Styrene Polymer (C) organic clay Kinds weight% Kinds weight% Kinds weight% Example One sPS 70 aPS 27 15A 3 2 sPS 70 aPS 21 15A 9 3 sPS 70 aPS 27 15A 3 4 sPS 70 SMA 27 15A 3 5 sPS 70 SMA 21 15A 9 6 sPS 70 SMA 27 15A 3 7 sPS 70 SEBS-MA 27 15A 3 8 sPS 70 SEBS-MA 21 15A 9 9 sPS 70 SEBS-MA 27 15A 3

Example 1

aPS (molecular weight = 400000) and the organic clay were mixed at room temperature in a ratio of 9: 1, and then placed in a batch mixer and kneaded at a temperature of 200 rpm for 10 minutes at a speed of 50 rpm. sPS (molecular weight = 320000) and the mixture obtained before were mixed at 7: 3, and then placed in a batch mixer again and kneaded at a temperature of 280 ° C. for 6 minutes to prepare a nanocomposite material. In the prepared nanocomposite, the d-space of the organic clay was 3.52 nm, showing an insertion structure of 0.55 nm increased from 2.97 nm of the original d-space of the organic clay. The obtained nanocomposite material was injection molded to prepare a specimen for mechanical properties. The measurement results of the mechanical properties are shown in Table 2.

Example 2

A nanocomposite material was prepared in the same manner as in Example 1 except that the aPS (molecular weight = 400000) and the organic clay were mixed at a ratio of 7: 3 instead of at a ratio of 9: 1. In the prepared nanocomposites, the d-space of the organic clay was 3.60 nm, which showed an insertion structure of 0.63 nm which is increased from 2.97 nm of the original d-space of the organic clay. Table 2 shows the measurement results of the mechanical properties of the nanocomposite material.

Example 3

sPS, aPS and organic clay were mixed at room temperature in a ratio of 70: 27: 3, and then placed in a batch mixer and kneaded at a temperature of 280 ° C. at 50 rpm for 6 minutes to prepare a nanocomposite material. In the nanocomposite, the d-space of the organic clay was 3.56 nm, showing an insertion structure of 0.58 nm increased from 2.97 nm of the original d-space of the organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 4

A nanocomposite material was prepared in the same manner as in Example 1, except that SMA (molecular weight = 220000, MA = 7% by weight) was used instead of aPS (molecular weight = 400000). In the prepared nanocomposites, the d-space of the organic clay was 3.25 nm, which showed an insertion structure increased by 0.28 nm from 2.97 nm of the original d-space of the organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 5

Same as Example 1 except that SMA (molecular weight = 220000, MA = 7% by weight) and organic clay are mixed at a 7: 3 ratio, instead of mixing aPS (molecular weight = 400000) and organic clay at a ratio of 9: 1. The nanocomposite material was prepared by the method. In the prepared nanocomposite material, the d-space of the organic clay was 3.29 nm and showed an insertion structure increased by 0.32 nm from the original d-space of 2.97 nm of the organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 6

sPS, SMA and organic clay were mixed at room temperature in a ratio of 70: 27: 3, and then placed in a batch mixer and kneaded at a temperature of 280 ° C. for 6 minutes at 50 rpm to prepare a nanocomposite material. In the prepared nanocomposites, the organic clay d-space was 3.33 nm, showing an insertion structure 0.38 nm larger than the original d-space 2.97 nm of organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 7

A nanocomposite material was prepared in the same manner as in Example 1, except that SEBS-MA (MA = 5 wt.%) was used instead of aPS (molecular weight = 400000). The prepared nanocomposite material exhibited a completely peeled structure in which no peak was observed for d-space of organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 8

A nanocomposite material was prepared in the same manner as in Example 2, except that SEBS-MA (MA = 5 wt.%) was used instead of aPS (molecular weight = 400000). In the prepared nanocomposites, the d-space of the organic clay was 3.38 nm, showing an insertion structure of 0.41 nm increased from the original d-space of 2.97 nm of the organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

Example 9

sPS, SEBS-MA and organic clay were mixed at room temperature in a ratio of 70: 27: 3, and then placed in a batch mixer and kneaded at a temperature of 280 ° C. for 6 minutes to prepare a nanocomposite material. The prepared nanocomposite material exhibited a completely peeled structure in which no peak was observed for d-space of organic clay. Injection molding of the nanocomposite material to prepare a specimen for mechanical properties, the measurement results are shown in Table 2.

FIG. 3 shows the respective X-ray spectra for the composition prepared by 15A product, Examples 1, 4 and 7 used as organoclay in the examples of the present invention. 4 shows the respective X-ray spectra of the compositions prepared by 15A product, Example 3, Example 6 and Example 9 used as organoclay in the examples of the present invention.

The mechanical properties of the tensile strength, flexural rigidity and impact strength of the nanocomposite prepared in Example 1-9 were measured and the results are shown in Table 2.

division Tensile strength (kgf / cm ² ) Flexural Stiffness (kgf / cm ² ) Impact strength (kgfcm / cm) Example One 208 39250 0.9 2 301 46730 0.7 3 139 39140 0.8 4 315 42350 0.7 5 340 48910 0.7 6 181 40690 0.8 7 316 28470 4.0 8 311 31400 2.6 9 320 28120 3.8

In Example 1-9, the nanocomposites prepared by the method of the present invention were found to maintain the layered structure which was opened or peeled off without collapse of the layer structure even though the melt was kneaded at a high temperature of 280 ° C. .

In the present invention, by applying an amorphous styrene-based polymer, the organic clay layers can be dispersed in the form of an insertion structure or a peeling structure in the crystalline polystyrene through melt kneading at a high temperature of 250 ° C. or higher, and also the mechanical properties such as bending stiffness and tensile strength can be dispersed. It has the effect of the invention providing a nanocomposite material having excellent physical properties and a method for producing the same.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of the present invention will be apparent from the appended claims.

Claims (9)

(1) preparing a composite material by mixing the amorphous styrene-based polymer and the organic clay in a batch mixer or an extruder and melting and kneading at a glass transition temperature of the amorphous styrene-based polymer or higher; (2) melt kneading the crystalline polystyrene and the composite material above the melting temperature of the crystalline polystyrene; Method for producing a nanocomposite material, characterized in that consisting of steps. The method of claim 1, wherein the weight ratio of the amorphous styrene-based polymer and the organic clay in the step (1) is in the range of 1: 1 to 20: 1. The method of claim 1, wherein the weight ratio of the crystalline polystyrene and the composite material of the step (2) has a range of 1: 1 to 20: 1. A method for producing a nanocomposite material for crystalline polystyrene, wherein the crystalline polystyrene, the amorphous styrene polymer, and the organic clay are simultaneously introduced into a batch mixer or an extruder and melt kneaded above the melting temperature of the crystalline polystyrene. The method of claim 4, wherein the composition of the amorphous styrene-based polymer has a range of 5 to 30% by weight, and the composition of the organic clay has a range of 1 to 30% by weight. . The method according to any one of claims 1 to 5, wherein the crystalline polystyrene is a styrenic polymer having stereoregularity, isotactic polystyrene, syndiotactic polystyrene, syndiotactic polymethylstyrene, syndiotactic polyethyl. Styrene, syndiotactic polyisopropylstyrene, syndiotactic poly tertiary butyl styrene, syndiotactic polyvinyl styrene, syndiotactic polychlorostyrene, syndiotactic polybromostyrene, syndiotactic polyfluorostyrene, synth A method for producing a nanocomposite material, characterized in that it is selected from the group consisting of an atactic styrene-isoprene copolymer and a syndiotactic styrene-vinylnaphthalene copolymer. 6. The at least one polystyrene polymer of claim 1, wherein the amorphous styrene-based polymer is a polymer compatible with the crystalline polystyrene and forming an intercalating or exfoliating structure with the organic clay. 7. , Styrene-maleic anhydride copolymer, oxazoline polystyrene, styrene-butadiene block copolymer, a block copolymer of styrene and ethylene or butylene, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block A copolymer and maleic anhydride are selected from the group consisting of grafted styrene-ethylene-butylene-styrene block copolymers. 6. The organic clay according to any one of claims 1 to 5, wherein the organoclay is a silicate mineral having a 2: 1 layer structure substituted with alkylammonium ions or alkylphosphonium ions, and montmorillonite, hector. Method for producing a nanocomposite material characterized in that it is selected from the group consisting of light (hectorite) and saponite (saponite). A nanocomposite material produced by the method of any one of claims 1 to 5.