KR102164256B1 - Biodegradable polymer composites having improved mechanical properties - Google Patents

Abstract

The present invention is a matrix of a first polymer comprising a biodegradable polymer; A second polymer dispersed in the matrix to form a dispersed phase; And anisotropic particles arranged in the interface between the matrix of the first polymer and the dispersed phase of the second polymer or the matrix of the first polymer, wherein the anisotropic particles are biodegradable, which is a mixture of organic clay and natural clay. It relates to a polymer composite.
According to the present invention, as anisotropic particles, which are a mixture of hydrophobic organic clay and hydrophilic natural clay, are arranged between the first polymer including the biodegradable polymer and the second polymer incompatible with the first polymer, the agent As the affinity between the first polymer and the second polymer is increased, morphology is controlled, and mechanical properties such as tensile elongation may be improved.

Description

Biodegradable polymer composites with improved mechanical properties {BIODEGRADABLE POLYMER COMPOSITES HAVING IMPROVED MECHANICAL PROPERTIES}

The present invention relates to a biodegradable polymer composite material having improved mechanical properties, and more particularly, to a biodegradable polymer composite material including anisotropic particles and improved mechanical properties along with morphology control.

Biodegradable polymers produced by using starch or aliphatic polyester as raw materials have a great advantage that they exhibit various physical properties of general plastic materials, but are biodegraded by bacteria or microorganisms, and waste disposal costs are consumed much less than general plastic materials. Various studies have been conducted on this.

Polylactic acid (PLA), as one of the biodegradable polyester polymers, is attracting attention as an alternative to overcome the problems of environmental pollution due to the depletion of petroleum resources and the non-degradability of plastic products. It is known to have resource saving properties and excellent thermal processing properties.

However, the shortcomings such as brittleness, low decomposition rate, and weak melt strength resulting from the hydrophobic structure of PLA make PLA have many limitations in its practical application.

As a method for toughening PLA, a method of toughening PLA by blending an elastic polymer having high softness properties, such as natural rubber, has been attempted. However, the polymer blend obtained by the above method suffers from a problem of physical property degradation that does not cause a decrease in impact strength due to the incompatibility between the matrix polymer (PLA) and the dispersed polymer (natural rubber), and the resulting interfacial formation. Involved. Therefore, it is necessary to prevent deterioration of mechanical properties through morphology control in the blend of the two polymers.

On the other hand, when a dispersion stabilizer is used for morphology control, mechanical properties such as modulus of the blend may be reduced. For example, when the morphology is controlled using spherical dispersion stabilizer particles, the added content must be high, and thus flowability of the blend may be inhibited, thereby reducing processability and moldability.

Accordingly, there is a need to develop an additive capable of improving the morphology and mechanical properties of the polymer blend even with a small amount of the biodegradable polymer blend.

The present invention is to solve the above problems, one object of the present invention is a biodegradable polymer composite material containing anisotropic particles capable of improving mechanical properties while controlling morphology by supplementing incompatibility between polymer blends Is to provide.

According to an aspect of the present invention, a matrix of a first polymer comprising a biodegradable polymer; A second polymer dispersed in the matrix to form a dispersed phase; And an anisotropic particle arranged in the interface between the matrix of the first polymer and the dispersed phase of the second polymer or the matrix of the first polymer is provided.

The anisotropic particles may be a mixture of hydrophobic organic clay and hydrophilic natural clay, or a mixture of hydrophobic calcium carbonate and hydrophilic calcium carbonate.

The natural clay may be made of a cation of an anionally charged aluminum or magnesium silicate layer and a sodium ion (Na ⁺ ) or a potassium ion (K ⁺ ) filling between the anionally charged aluminum or magnesium silicate layers. .

The natural clay is montmorillonite, hectorite, saponite, beidellite, nontronite, vermiculite, halloysite, or two of them. It may be a mixture of the above.

The organic clay is organic by replacing ions existing on the surface or between layers of natural clay with a hydrophobic functional group, specifically, a substance having an alkyl ammonium ion containing an alkyl group having 1 to 10 carbon atoms, or a ω-amino acid (NH ₂ (CH ₂ ) _n-1 COOH, where n is an integer of 2 to 18) may be organicized using a hydrophobic material.

The hydrophobic material is dimethyl dihydrogenated-tallow ammonium, dimethyl benzyl hydrogenated-tallow ammonium, dimethyl hydrogenated-tallow ammonium (2-ethyl Hexyl) ammonium (dimethylhydrogenated-tallow (2-ethylhexyl) ammonium), or a mixture of two or more thereof.

The first polymer may be polylactic acid, polycaprolactone, polybutylene succinate, polybutylene adipate, polyethylene succinate, polyhydroxy alkylate, polyhydroxyalkanoate, or a mixture of two or more thereof. .

The second polymer may be natural rubber, polyolefin, polyolefin elastomer, or a mixture of two or more of them.

The first polymer and the second polymer may be included in a weight ratio of 90:10 to 60:40.

The anisotropic particles may be included in 0.3 to 10% by weight, specifically 0.3 to 5% by weight of the total weight of the biodegradable polymer composite.

The mixing weight ratio of the organic clay and natural clay may be 30:70 to 70:30.

The mixing weight ratio of the hydrophobic calcium carbonate particles and the hydrophilic calcium carbonate particles may be 30:70 to 70:30.

The biodegradable polymer composite material according to an aspect of the present invention includes anisotropic particles arranged between the first polymer including the biodegradable polymer and the second polymer that is incompatible with the first polymer, and thus the first polymer and the second polymer. The affinity between the polymers is increased so that the morphology is controlled and mechanical properties such as tensile elongation can be improved.

1A is to show a state in which organic clay (C20A) and natural clay (CNa ⁺ ) having different surface properties from each other are dispersed in a PLA/NR (7:3) blend.
Figures 1b and 1c are the measurement results of morphology changes and rheological properties (G', G") according to the respective contents of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively Is shown.
2A and 2B show the measurement results of tensile strength and tensile elongation according to each content of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively.
3 shows the degree of increase in tensile elongation when a mixture of organic clay (C20A) and natural clay (CNa ⁺ ) is added to the PLA/NR (7:3) blend.
Figures 4a and 4b show the measurement results of rheological properties (G', G") according to the single or combination use of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively. Is shown.
5 is a TEM image showing the morphology of a polymer composite based on PLA/NR/effervescent particles (a mixture of organic clay and natural clay) according to Example 2 according to an enlarged magnification.
6 is a TEM image showing the morphology of the PLA/NR/effervescent particle (organic clay alone)-based polymer composite according to Comparative Example 5 according to enlarged magnification.
7a and 7b are graphs showing tensile strength and tensile elongation according to the mixing ratio of PLA/NR and the content of organic clay in the PLA/NR/effervescent particle (mixture of organic clay and natural clay)-based polymer composite, respectively.

Since the present invention can apply various transformations and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

The biodegradable polymer composite material according to an embodiment of the present invention includes a matrix of a first polymer including a biodegradable polymer; A second polymer dispersed in the matrix to form a dispersed phase; And an anisotropic particle arranged in the interface between the matrix of the first polymer and the dispersed phase of the second polymer, or in the interior of the first or second polymer phase.

The first polymer is a main matrix polymer and includes a biodegradable polymer having environmental friendliness, biocompatibility, resource saving properties, and excellent thermal processing properties. Examples of such biodegradable first polymers include polylactic acid, polycaprolactone, polybutylene succinate, polybutylene adipate, polyethylene succinate, polyhydroxy alkylate, polyhydroxyalkanoate, or two or more of them. Mixtures, preferably polylactic acid, polycaprolactone, or mixtures of two or more thereof.

In particular, polylactic acid (PLA), which represents a biodegradable polymer, has the advantage of being eco-friendly because of its biodegradability, but has a disadvantage in that it is very brittle and cannot be applied in various ways. In order to overcome this disadvantage, it is useful to blend and use other polymers that are incompatible with the first polymer.

That is, the second polymer is a component blended to improve physical properties such as processability and barrier property of the biodegradable polymer as described above, and examples thereof include natural rubber, polyolefin, polyolefin elastomer, or a mixture of two or more of them, Examples of the polyolefin include polyethylene, polypropylene, polybutadiene, poly EVA (ethylene vinyl acetate), polyamide, polyethylene terephthalate, and the like.

In particular, natural rubber may be preferably used as the second polymer. Natural rubber (NR) is a material rich in elasticity obtained from so-called rubber plants and generally contains polyisoprene as a main component. And the unmodified natural rubber according to the present invention refers to a natural rubber that is not modified, that is, epoxidized or acrylic modified. Such natural rubber can exhibit high elasticity because energy applied from the outside is stored in the form of thermal energy due to distortion of the double bond in the cis-isoprene repeating unit.

In one embodiment of the present invention, the first polymer and the second polymer may be included in a weight ratio of 90:10 to 60:40, but are not limited thereto.

However, the second polymer including natural rubber is incompatible with the first polymer, which is a biodegradable polymer, and due to this incompatibility, phase separation between the matrix polymer and the dispersed polymer may occur.

To compensate for this, in the present invention, anisotropic particles are added to the blend of the first polymer and the second polymer.

The anisotropic particles mean a mixture of two or more having different surface properties, and since these particles of different surface properties are not compatible with the first polymer and the second polymer, the interaction between the anisotropic particles is It is maximized and the particle structure is effectively formed. For example, when particles located at the interface through the interaction between anisotropic particles form a particle interface layer, the interfacial tension between the first and second polymers is lowered and the interfacial modulus is increased to control the morphology and at the same time mechanical properties. It can provide an enhancing effect.

In a preferred embodiment, the anisotropic particles specifically comprise a mixture of organic clays having hydrophobic surface properties and natural clays having hydrophilic surface properties.

The natural clay is composed of a cation of an anionally charged aluminum or magnesium silicate layer, and a sodium ion (Na ⁺ ) or potassium ion (K ⁺ ) filling between the anionally charged aluminum or magnesium silicate layers, Examples include montmorillonite, hectorite, saponite, beidellite, nontronite, vermiculite, halloysite, or a mixture of two or more of them. There is this.

The organic clay is organic by substituting ions present on the surface or between layers of natural clay with a hydrophobic functional group, such as a substance having an alkyl ammonium ion containing an alkyl group having 1 to 10 carbon atoms or an ω-amino acid (NH ₂ ( CH ₂ ) _n-1 COOH, where n is an integer from 2 to 18). Examples of the hydrophobic material usable for such organizing include dimethyl dihydrogenated-tallow ammonium, dimethyl benzyl hydrogenated-tallow ammonium, and dimethyl hydrogenated. -Dimethylhydrogenated-tallow (2-ethylhexyl) ammonium, or mixtures of two or more of these.

When the clay substituted with the organic functional group as described above is added to the incompatible polymer blend, it is located at the interface of the two polymers to lower the interfacial tension, thereby increasing the morphological strain, including reducing the size of the droplets of the dispersed phase. In addition, the organic clay may be arranged inside the first or second polymer phase.

On the other hand, the natural clay and the organic clay may exhibit different dispersion states in the polymer blend due to different surface properties. For example, FIG. 1A is for showing a state in which organic clay (C20A) and natural clay (CNa ⁺ ) having different surface properties from each other are dispersed in a PLA/NR (7:3) blend. From Figure 1a, in the case of organic clay having a more affinity for a hydrophobic polymer material, it can be confirmed that the size is reduced by 1 μm in the polymer blend (70:30 PLA:NR) and is somewhat uniformly dispersed ( left). On the other hand, natural clay, even with the same content, has a very low dispersibility in the polymer blend and maintains a size of 20 μm or more (right), so it hardly affects the structure of the polymer blend.

In particular, when the organic clay has a plate-like layered structure like nano clay, the surface is replaced with organic functional groups, so it is well peeled in the hydrophobic polymer matrix, and the particle filling effect is significantly increased even with a small amount of the polymer. You can change the blend structure. Moreover, when positioned at the interface of the polymer blend, morphology can be controlled, and toughening can be induced through this.

On the other hand, when the content of the added organic clay exceeds a certain amount, a phenomenon of reducing mechanical properties such as tensile elongation of the polymer blend may occur due to particle aggregation. However, it is difficult to predict a suitable particle content for the effect of increasing mechanical properties because the critical content of the particles in which the particle agglomeration occurs varies depending on the degree of particle dispersion. For example, when the organic clay is added to the polymer blend in excess of 0.63% by weight, which is a critical content determined according to percolation theory to form a network by being arranged in the polymer blend, the particle content would have been mixed with about 2% by weight. When the value of the storage modulus G'in the low frequency region increases the loss modulus G" (see Fig. 1C), it can be seen that the mixture must exceed the critical content in order to obtain a particle structure. This means that agglomeration of the particles has occurred partially, and even if the value of G'is increased to increase its content, it is not advantageous when considering mechanical properties such as tensile elongation, that is, up to the critical content of the organic clay. When the tensile elongation of the polymer blend is increased and the critical content is exceeded, the tensile elongation is rather reduced.

This decrease in tensile elongation can be overcome by the mixed use of the natural clay. That is, when natural clay that does not exhibit percolation within a predetermined content range is added to the polymer blend by mixing with organic clay up to the critical content of percolation, the tensile elongation may be unexpectedly increased. This is because the particles are intensively located in the interface layer having a low polymer chemical potential due to the interaction between the natural clay dispersed in the first polymer and the organic clay exhibiting interfacial site specificity. As a result, the anisotropic clay particles located at the interface can increase the connection bonding force between the polymer phases by physical wetting by the particle surface energy between the two polymer phases without thermodynamic affinity, from which it is resistant to external deformation. By increasing the tensile elongation can be increased.

In addition, in order to improve the tensile elongation as described above, a mixture of inorganic particles having different surface properties as anisotropic particles, such as hydrophobic calcium carbonate (CaCO ₃ ) particles (cPCC) coated with stearic acid and coating Non-hydrophilic calcium carbonate (CaCO ₃ ) particles (uPCC) can be used.

In one embodiment of the present invention, the anisotropic particles may be included in an amount of 0.3 to 10% by weight of the total weight of the biodegradable polymer composite.

For example, when the anisotropic particles are the organic clay and natural clay, these clays may be included in a small amount of 0.3 to 5% by weight, specifically 0.3 to 0.9% by weight, or 0.75% of the total weight of the biodegradable polymer composite. have. When the above content is satisfied, it is advantageous in that the intended effect is achieved without causing deterioration in processability and moldability due to excessive addition content.

On the other hand, when the anisotropic particles are hydrophobic calcium carbonate particles and hydrophilic calcium carbonate particles, the anisotropy (aspect ratio) is lower than that of clay and particle separation does not occur, so the content slightly increases to achieve the intended effect, but hydrophobicity and Due to the mixed addition of hydrophilic particles, the dispersion increase effect can be achieved in a small amount compared to the existing addition amount. Accordingly, these calcium carbonate particles may be included in an amount of 1 to 10% by weight, such as 3 to 8% by weight or 3 to 6% by weight.

In addition, the mixing weight ratio of the organic clay and natural clay may be 30:70 to 70:30, specifically 50:50 to 60:40. When the mixing ratio range is satisfied, it is advantageous in terms of controlling the morphology and improving the tensile elongation. Similarly, the mixing weight ratio of the hydrophilic calcium carbonate particles and the hydrophobic calcium carbonate particles may be 30:70 to 70:30, specifically 50:50 to 60:40.

The biodegradable polymer composite according to the present invention may be prepared by blending the first polymer, the second polymer, and the anisotropic particles in a predetermined amount as described above.

The blending process is performed at a melting point of the first polymer (eg, 155 to 165° C. in the case of polylactic acid) at a high level of about 30 to 70° C. 180 to 230° C., specifically at 190 to 200° C., 50 to 150 rpm, in detail. Can be carried out for 3 to 10 minutes, such as 7 minutes, at a speed of 80 to 100 rpm.

The biodegradable polymer composite prepared in this way uses a small amount of anisotropic particles composed of a mixture of organic clay and natural clay along with the first biodegradable polymer and the second polymer incompatible therewith, thereby stabilizing the interface of the polymers to control the morphology. At the same time, mechanical properties such as tensile elongation can be improved.

Hereinafter, examples will be described in detail to aid understanding of the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

Examples 1 to 3: Preparation of biodegradable polymer composites based on PLA/NR/anisotropic particles (organic/natural clay mixture)

, density=2.86g/cc, BYK, USA)를 재료로서 사용하였으며, 모든 재료는 수분을 제거하기 위해 80℃ 진공 오븐에서 하루 동안 건조시켰다.Polylactic acid (PLA, 4032D, Mn=90,00g/mol, Mw=181,000g/mol, Natureworks, USA) as the first polymer forming the matrix, and natural rubber (NR) as the second polymer forming the dispersed phase. , CSR5, Cambodia) was used. Organic clay (Cloisite 20A, density=1.77g/cc, Southern Clay Product, USA) and natural clay (Cloisite) having two hydrogenated tallow (HT) and two methyl groups as anisotropic particles

, density=2.86g/cc, BYK, USA) was used as a material, and all materials were dried in a vacuum oven at 80° C. for one day to remove moisture.

The materials were mixed at 200° C. for 7 minutes at 100 rpm using an intensive mixer (Rheocompmixer 600, MKE, Korea) in the amounts shown in Table 1 below.

PLA NR Anisotropic particles
(0.75% by weight based on the total parts by weight of PLA and NR) Organic Clay (C20A) Natural Clay (CNa ⁺ ) Example 1 90 parts by weight 10 parts by weight 0.45% by weight 0.3% by weight Example 2 70 parts by weight 30 parts by weight Example 3 60 parts by weight 40 parts by weight

Comparative Example 1: Preparation of PLA/NR polymer blend

A polymer blend of PLA/NR was prepared by performing the same process as in Example 2, except that anisotropic particles were not mixed.

Comparative Examples 2 to 4: Preparation of PLA/NR/organic or natural clay-based biodegradable polymer composites

A biodegradable polymer composite was manufactured by performing the same process as in Example 2, except that organic clay or natural clay alone was mixed in the amount shown in Table 2 below.

PLA NR Organic clay or natural clay used alone
(Based on total parts by weight of PLA and NR) Comparative Example 1 70 parts by weight 30 parts by weight - Comparative Example 2 70 parts by weight 30 parts by weight Natural clay (CNa ⁺ ) 0.3% by weight Comparative Example 3 70 parts by weight 30 parts by weight Organic Clay (C20A) 0.45% by weight Comparative Example 4 70 parts by weight 30 parts by weight Natural clay (CNa ⁺ ) 0.75% by weight Comparative Example 5 70 parts by weight 30 parts by weight Organic Clay (C20A) 0.75% by weight

Experimental Example 1: Measurement of changes in morphology, rheological properties, and mechanical properties of a PLA/NR polymer blend according to the content of organic or natural clay

In order to analyze the effect of organic clay and natural clay on the structural change and rheological properties of the PLA/NR polymer blend, a sample was prepared by mixing the materials with the contents shown in Table 3 in the same process as in Example 2.

PLA NR Clay content
(Based on total parts by weight of PLA and NR) 70 parts by weight 30 parts by weight 0% by weight 0.5% by weight of organic clay (C20A) Organic Clay (C20A) 2% by weight Organic Clay (C20A) 5% by weight Natural clay (CNa ⁺ ) 0.5% by weight Natural clay (CNa ⁺ ) 2% by weight Natural clay (CNa ⁺ ) 5% by weight

Each prepared sample was annealed in a hot press (CH4386, Carver) at 200° C. for 6 minutes, and then a sample was prepared using a disc-like mold having a diameter of 25 mm and a thickness of 0.4 mm. At this time, the molding temperature was 200°C, and the molding time was 6 minutes.

The cross section of the specimen was observed with a High Resolution-Transmission Electron Microscope (TEM) (JEOL Ltd, Japan) to analyze the change in morphology according to the clay content.

In addition, changes in dynamic rheological properties of the specimen were measured using RMS800 (Rheometrics, USA), a strain-controlled rheometer. At this time, all measurements were performed in a linear viscoelastic region at 190°C, and frequency experiments were performed at 0.1 rad/s to 100 rad/s with a strain value between 1% and 15%.

Meanwhile, the mechanical properties of the specimen were cut to ASTM D639 Type V and measured using UTM (LF plus, Lloyd instruments Ltd).

Figures 1b and 1c are the measurement results of morphology changes and rheological properties (G', G") according to the respective contents of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively On the other hand, Fig. 1c is a schematic diagram of a storage modulus (G') and a loss modulus (G") of 0.1 rad/s in the frequency experiment, and the lowest frequency of 0.1 rad/s is selected in the frequency experiment. The reason is that the behavior on a long time scale reflects the behavior of the whole polymer, and this behavior is judged to be correlated with the whole morphology.

From Figures 1b and 1c, it can be seen that the organic clay (C20A) greatly changes the morphology and rheological properties of the polymer blend, while the change in the morphology and rheological properties due to natural clay (CNa ⁺ ) is not very large.

On the other hand, Figures 2a and 2b show the measurement results of tensile strength and tensile elongation according to each content of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively, It can be seen that the effect on the tensile strength and tensile elongation of the polymer blend is different when the clay content of is less than 1% by weight.

Experimental Example 2: Measurement of changes in mechanical properties of PLA/NR polymer blends according to the use of a mixture of organic clay and natural clay

To evaluate the degree of change in tensile elongation when a mixture of organic clay (C20A) and natural clay (CNa+) is added to the PLA/NR (7:3) blend, Example 2 (PLA/NR (7:3) and C20A 0.45wt% + CNa ⁺ 0.3wt%) for the biodegradable polymer composite material as described in Experimental Example 1, after measuring the tensile elongation by producing a specimen, the measurement result is compared with the graph of C20A in Fig. Shown in.

Figure 3 is a PLA / NR (7: 3) to show the organic clay (C20A) and natural clay of the tensile elongation percentage in the case where a mixture of (CNa ⁺⁾ added to increase the degree to blend, with the C20A in the polymer blend CNa ⁺ It can be seen that the tensile elongation is remarkably increased by being used in a predetermined content range.

Experimental Example 3: Analysis of the rheological properties of PLA/NR polymer blends according to the use of organic clay and natural clay alone or in combination

For the composite materials of Example 2 and Comparative Examples 1 to 5 in which PLA/NR was mixed at a weight ratio of 7:3, specimens were prepared as described in Experimental Example 1 to measure rheological properties, and the results are shown in FIG. 4A And 4b.

Figures 4a and 4b show the measurement results of rheological properties (G', G") according to the single or combination use of organic clay (C20A) and natural clay (CNa ⁺ ) added to the PLA/NR (7:3) blend, respectively. Is shown.

Specifically, when natural clay (CNa ⁺ ) is added alone in an amount of 0.3% by weight (Comparative Example 2) and 0.75% by weight (Comparative Example 4), when the frequency range is 0.1 to 100 rad/s, PLA/NR (7 :3) Compared to the blend (Comparative Example 1), the storage modulus (G') and the loss modulus (G") almost overlap, but rather slightly decreased in the high frequency region.

On the other hand, when organic clay (C20A) was added alone in an amount of 0.45% by weight (Comparative Example 3), the value of G'was about 200 at a frequency of 0.1 rad/s, and when it was 0.75% by weight (Comparative Example 5) The value of G'increased to about 600.

And, it was found that when both clays were added (Example 2), the value of G'at a low frequency of 0.1 rad/s was slightly increased than when only 0.45 wt% of C20A was added (Comparative Example 3), showing higher elasticity. I can. On the other hand, compared to the case where only 0.75% by weight of C20A was added (Comparative Example 5), the value of G'was smaller.

From these results, it can be seen that the combination use of organic clay (C20A) and natural clay (CNa ⁺ ) provides a rheological property similar to that of organic clay (C20A) alone.

Experimental Example 4: Morphology analysis of PLA/NR polymer blend according to the use of organic clay and natural clay alone or in combination

For the composite materials of Example 2 and Comparative Example 5 in which PLA/NR was mixed at a weight ratio of 7:3, specimens were prepared as described in Experimental Example 1, and the cross-section was observed by TEM.

5 is a TEM image showing the morphology of a polymer composite based on PLA/NR/effervescent particles (a mixture of organic clay and natural clay) according to Example 2 according to an enlarged magnification. From FIG. 5, it can be seen that organic and natural clay surround the interface of the two incompatible polymers, and some exist on the PLA. Although it is not possible to distinguish between the two clay particles, some of them are peeled off and some form two or three layers, and it can be seen that peeling and dispersion are effectively performed without the need for particle discrimination. It can be seen that the peeled-dispersed particles are located at the interface to stabilize the interface, and other parts are present in the PLA phase. It was confirmed that the second polymer was not dispersed in the rubber phase. Particles are selectively dispersed on the interface and on the first polymer, and have the effect of increasing the rheological properties of the first polymer phase with low viscosity and the effect of reducing the interfacial tension, so that the morphology of the polymer blend is made from a spherical structure to a fibril structure. It can be seen that it changes to. Some can see that the two phases maintain a co-continuous structure with each other.

On the other hand, Figure 6 is a TEM image showing the morphology of the PLA/NR/effervescent particle (organic clay alone)-based polymer composite according to Comparative Example 5 according to magnification, and in this case, the organic clay particles of a plate-shaped structure also show a continuous structure. It can be seen that it is located at the interface between the formed dispersed phase NR and the main matrix PLA phase.

As described above, it can be seen that when organic clay is used alone or in combination with natural clay, it is positioned at the interface between the two polymers of PLA and NR and induces toughening of the blend. On the other hand, when natural clay is used alone, it is mostly located on the first polymer, and the peel-dispersion effect is very insignificant, but when it is mixed with organic clay, the peel-dispersing effect increases and the blend morphology with organic clay changes, resulting in composite materials. It induces toughening.

Experimental Example 5: Measurement of changes in mechanical properties depending on the mixing ratio of organic clay and natural clay

In order to analyze the effect of the mixing ratio of the two clays on the mechanical properties of the PLA/NR polymer blend in the polymer composite based on PLA/NR/effervescent particles (a mixture of organic clay and natural clay), the composition of Examples 1 to 3 By varying the ratio of the organic clay in, the specimen was prepared as described in Experimental Example 1, and then the tensile strength and tensile elongation were measured.

Figures 7a and 7b show the tensile strength and tensile elongation according to the mixing ratio of PLA/NR and the ratio of organic clay in the total clay content in the PLA/NR/effervescent particle (mixture of organic clay and natural clay)-based polymer composite, respectively. It is a graph.

From FIGS. 7A and 7B, it can be seen that the optimum clay mixing ratio representing the maximum tensile elongation is around 60% of the organic clay (C20A).

의 비율에 따라 강인화(toughening) 정도가 달라질 수 있으며, 이로부터 비등방성 입자의 혼합물을 고분자 블렌드의 계면 특성을 제어함과 동시에 최적의 기계적 물성을 이끌어 낼 수 있다.As such, C20A and C20A in the total amount of clay fixed according to each composition of PLA:NR

Depending on the ratio of, the degree of toughening may vary, from which the mixture of anisotropic particles can control the interfacial properties of the polymer blend and at the same time lead to optimal mechanical properties.

Example 4: Preparation of biodegradable polymer composite based on PLA/NR/anisotropic particles (hydrophobic calcium carbonate/hydrophilic calcium carbonate mixture)

Polylactic acid (PLA, 4032D, Mn=90,00g/mol, Mw=181,000g/mol, Natureworks, USA) as the first polymer forming the matrix, and natural rubber (NR) as the second polymer forming the dispersed phase. , CSR5, Cambodia) was used. As anisotropic particles, hydrophobic calcium carbonate (CaCO ₃ ) particles (cPCC) coated with stearic acid and uncoated hydrophilic calcium carbonate (CaCO ₃ ) particles (uPCC) were used. At this time, the cPCC and uPCC particles each had an average particle diameter of 100 nm. All materials were dried in a vacuum oven at 80° C. for one day to remove moisture. The materials were mixed at 200° C. for 7 minutes at 100 rpm using an intensive mixer (Rheocompmixer 600, MKE, Korea) in the amounts shown in Table 4 below.

Subsequently, as described in Experimental Example 1, a specimen was prepared and the tensile elongation was measured.

Comparative Example 6: Preparation of PLA/NR/hydrophobic calcium carbonate-based biodegradable polymer composite

The same procedure as in Example 4 was performed, except that the uncoated hydrophilic calcium carbonate (CaCO ₃ ) particles (uPCC) were not used, and the remaining components were mixed in the amounts shown in Table 4 below.

PLA NR Anisotropic particles
(Based on the content of PLA) Elongation at break point,% cPCC
(Hydrophobic particles) uPCC
(Hydrophilic particles) Example 4 85 parts by weight 15 parts by weight 3% by weight 3% by weight 86% Comparative Example 6 85 parts by weight 15 parts by weight 12% by weight 0 85%

From Table 4, in the case of mixing calcium carbonate into two types of hydrophilic particles and hydrophobic particles and mixing them in the PLA/NR blend (Example 4), when only the hydrophilic particles are mixed in a higher content (Comparative Example 6) It can be seen that it shows a more improved tensile elongation than that. That is, even in the case of spherical calcium carbonate, as the hydrophilic and hydrophobic particles of different surface properties are mixed and used, the content can be reduced and toughening can be induced without reducing other properties.

As described above, a specific part of the present invention has been described in detail, and for those of ordinary skill in the art, it is obvious that this specific technology is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Therefore, it will be said that the practical scope of the present invention is defined by the appended claims and their equivalents.

Claims (15)

A matrix of a first polymer comprising a biodegradable polymer;
A second polymer dispersed in the matrix to form a dispersed phase; And
Hydrophobic organic clay and hydrophilic natural clay are mixed in a weight ratio of 30:70 to 70:30 or hydrophobic calcium carbonate and hydrophilic calcium carbonate are mixed in a weight ratio of 30:70 to 70:30, and anisotropic particles,
The anisotropic particles exhibit different dispersion states in which some are arranged at the interface between the matrix of the first polymer and the dispersed phase of the second polymer, and some are arranged in the matrix of the first polymer according to the surface properties of hydrophobic or hydrophilic properties Phosphorus biodegradable polymer composite. delete The method of claim 1,
The natural clay is composed of a cation of an anionally charged aluminum or magnesium silicate layer and a sodium ion (Na ⁺ ) or a potassium ion (K ⁺ ) filling between the anionally charged aluminum or magnesium silicate layers. Polymer composites. The method of claim 3,
The natural clay is montmorillonite, hectorite, saponite, beidellite, nontronite, vermiculite, halloysite, or two of them. Biodegradable polymer composite material of the above mixture. delete delete delete The method of claim 1,
The first polymer is polylactic acid, polycaprolactone, polybutylene succinate, polybutylene adipate, polyethylene succinate, polyhydroxy alkylate, polyhydroxyalkanoate, or a mixture of two or more thereof. Polymer composites. The method of claim 1,
The second polymer is a natural rubber, polyolefin, polyolefin elastomer, or a biodegradable polymer composite material of two or more of them. The method of claim 1,
The first polymer and the second polymer are biodegradable polymer composites included in a weight ratio of 90:10 to 60:40. The method of claim 1,
The anisotropic particles are biodegradable polymer composites containing 0.3 to 10% by weight of the total weight of the biodegradable polymer composite. The method of claim 11,
The anisotropic particles are biodegradable polymer composites containing 0.3 to 5% by weight of the total weight of the biodegradable polymer composite. The method of claim 1,
The organic clay is a biodegradable polymer composite material that is organicized by replacing ions existing on the surface or between layers of natural clay with a hydrophobic functional group. The method of claim 13,
The organic clay is a material having an alkyl ammonium ion containing an alkyl group having 1 to 10 carbon atoms or a hydrophobic material of ω-amino acid (NH ₂ (CH ₂ ) _n-1 COOH, where n is an integer of 2 to 18) It is a biodegradable polymer composite that has been organicized. The method of claim 14,
The hydrophobic material is dimethyl dihydrogenated-tallow ammonium, dimethyl benzyl hydrogenated-tallow ammonium, dimethyl hydrogenated-tallow ammonium (2-ethyl Hexyl) ammonium (dimethylhydrogenated-tallow (2-ethylhexyl) ammonium), or a mixture of two or more of them, a biodegradable polymer composite.

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