KR20120129500A - Crystallization rate improved polylactic acid and method for preparing the same - Google Patents

Abstract

PURPOSE: An environment-friendly polylactic acid composition is provided to have high crystallization rate while having excellent Izod impact strength and flexural elasticity. CONSTITUTION: A polylactic composition comprises 100.0 parts by weight of polylactic acid, 0.1-10 parts by weight of organized surface-treated phyllite powder, and 0.1-10 parts by weight of carbon nanotubes. The average particle size of the phyllite powder is 0.5-500 micron. A manufacturing method of the polylactic acid composition comprises: a step of mixing polylactic acid, organized surface-treated phyllite powder and carbon nanotubes in solid state; and a step of melting and stirring the mixed polylactic acid, phyllite powder, and carbon nanotubes.

Description

Polylactic acid composition with improved crystallization rate and its preparation method {CRYSTALLIZATION RATE IMPROVED POLYLACTIC ACID AND METHOD FOR PREPARING THE SAME}

The present application relates to a polylactic acid composition and a method for preparing the same, and more particularly, to a polylactic acid composition having an improved crystallization rate and a method for producing the same.

A major concern for the global environment in recent years is the problem of global warming due to the accumulation of carbon dioxide, which appears with the depletion of fossil fuels. In order to solve this problem, research is being actively conducted to replace biodegradable plastics from carbon-based petrochemical plastics.

The definition of biodegradable resins has not yet been unified around the world, but must have the same level of functionality (strength, water resistance, moldability, heat resistance, etc.) as ordinary plastics in use, and the forces that cause degradation are detrimental to the natural material cycle. The most basic role of microorganisms (bacteria, fungi, etc.) is generally decomposed.

Poly lactic acid (PLA), a representative material of biodegradable plastics, has recently been in the spotlight due to many advantages such as relatively low cost, easy product molding, and excellent mechanical properties compared to other biodegradable materials. In addition, PLA is widely used in the medical field because it has a great advantage of biocompatibility as well as the application of plastic products as an environmentally friendly material.

However, in spite of various advantages, polylactic acid has poor thermal stability, resulting in lower molecular weight during processing, and polylactic acid has a lower crystallization rate, resulting in longer cycle times and lower molecular weight.

Accordingly, the present invention has been made to solve the problems of the prior art as described above and the technical problem has been requested from the past, the object of the present invention is a polylactic acid with excellent mechanical properties such as Izod impact strength and flexural modulus and fast crystallization rate It is to provide a composition.

Another object of the present invention is to provide a method for producing a polylactic acid composition which can be prepared by a simple method.

Still another object of the present invention is to provide a molded article made of the polylactic acid composition.

As a technical means for achieving the above technical problem, one aspect of the present invention, 100 parts by weight of polylactic acid; 0.1 to 10 parts by weight of the organically treated surface of the chalcedony powder; And 0.1 to 10 parts by weight of carbon nanotubes.

The organic surface-treated natural stone powder is one or more selected from the group consisting of fatty acids, amino acids, amides, esterified fatty acids, aliphatic amines, aromatic amines, ammonium salts, silanes, silane coupling agents, titanate coupling agents, and zirconate coupling agents. It may be an organic surface treatment with a surface treatment agent.

The organic surface-treated natural stone may be organically surface-treated with a fatty acid.

The organic surface-treated natural stone can be one having an average size of 0.5 to 500μm.

The carbon nanotubes may be one or more selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes.

The polylactic acid may be at least one selected from the group consisting of polylactic acid of L-optical isomer and polylactic acid of D-optical isomer.

The polylactic acid composition may further include at least one additive selected from the group consisting of antioxidants, weathering agents, mold release agents, colorants, sunscreen agents, nucleating agents, plasticizers, adhesive aids, pressure sensitive adhesives, and mixtures thereof.

Another aspect of the present invention provides a molded article made of the polylactic acid composition.

Another aspect of the present invention comprises the steps of (a) mixing a polylactic acid, organic surface-treated chalcedony powder and carbon nanotubes in a solid state; And (b) melting and mixing the mixed polylactic acid, the organically treated surface of the chalcedony powder, and the carbon nanotubes.

The step (b) may be carried out at a temperature of 190 to 230 ℃ in the twin screw extruder.

The method of preparing the polylactic acid composition may further include drying (c) the polylactic acid at 40 to 80 ° C. before the step (a).

The method of preparing the polylactic acid composition may further include a step (d) of drying the organically treated surface of the chalcedony powder at 110 to 150 ° C. before step (a).

The method of preparing the polylactic acid composition may further include drying (e) carbon nanotubes at 110 to 150 ° C. before step (a).

In the method of producing the polylactic acid composition, the polylactic acid composition is 100 parts by weight of polylactic acid; 0.1 to 10 parts by weight of the organically treated surface of the chalcedony powder; And 0.1 to 10 parts by weight of carbon nanotubes.

In the method of preparing the polylactic acid composition, the organic surface-treated chalcedony powder is fatty acid, amino acid, amide, esterified fatty acid, aliphatic amine, aromatic amine, ammonium salt, silane, silane coupling agent, titanate coupling agent and zirconate. It may be an organic surface treatment with at least one surface treatment agent selected from the group consisting of a coupling agent.

In the method of preparing the polylactic acid composition, the organically treated surface of the chalcedony powder may be organically surface treated with a fatty acid.

In the method of preparing the polylactic acid composition, the organically-treated surface of the Peach Rock powder may have an average size of 0.5 to 500 μm.

In the method of preparing the polylactic acid composition, the carbon nanotubes may be at least one selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes.

In the method of preparing the polylactic acid composition, the polylactic acid may be at least one selected from the group consisting of polylactic acid of L-optical isomer and polylactic acid of D-optical isomer.

The present invention can provide a polylactic acid composition which is biodegradable and environmentally friendly, has excellent mechanical properties such as Izod impact strength and flexural modulus, and has a high crystallization rate.

The present invention can also provide a method for producing a polylactic acid composition, which can produce the polylactic acid composition in a simple manner.

The present invention can also provide a molded article made of the polylactic acid composition.

Hereinafter, a preferred embodiment of the polylactic acid composition and its preparation method according to the present invention will be described in detail.

However, the following description is not intended to limit the present invention to specific embodiments, and it is to be understood that the present invention includes all conversions, equivalents, and substitutes included in the spirit and technical scope of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Furthermore, terms including an ordinal number such as first, second, etc. to be used below can be used to describe various elements, but the constituent elements are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

As a technical means for achieving the above technical problem, one aspect of the present invention, 100 parts by weight of polylactic acid; 0.1 to 10 parts by weight of the organically treated surface of the chalcedony powder; And 0.1 to 10 parts by weight of carbon nanotubes.

Polylactic acid

Polylactic acid (PLA) is prepared by the polymerization of lactic acid, a monomer. In lactic acid, there are two optical isomers, a polylactic acid of L-optical isomer and a polylactic acid of D-optical isomer. Lactide exists as L-lactide consisting of L-form lactic acid and D-lactide consisting of D-form only lactic acid.

Polylactic acid, a representative material of biodegradable plastics, has recently been in the spotlight due to many advantages such as relatively low cost, easy product molding, and excellent mechanical properties compared to other biodegradable materials. In addition, PLA is widely used in the medical field because it has a great advantage of biocompatibility as well as the application of plastic products as an environmentally friendly material. However, PLA has a problem in that the crystallization rate is slow in spite of various advantages, so that the processing cycle time is long and the molecular weight is decreased during melt processing.

Organicization  Surface treatment Mollum  powder

Phyllite is a type of metamorphic rock that is formed through the hydrolysis due to hydrothermal alteration, denaturation, weathering, and corrosion. The feldspar powder used in the present invention is a powder produced through a classification process by pulverizing domestic natural ore, and its main components include silica and alumina, which contain various kinds of metal oxides.

In addition, the feldspar powder contains pores of various sizes inside, and has a porosity that is almost similar to that of zeolite, but has a large fraction of foam, which is excellent in breathability and oil absorption.

The organically treated surface of the Peach Rock powder may have an organic compound introduced on the surface thereof to improve compatibility with the polymer resin, thereby improving mechanical properties.

The average size of the organic surface-treated natural stone powder is preferably from 0.5 to 500 μm, more preferably from 2 to 60 μm. When the size of the organically treated surface of the feldspar powder is small, the compatibility with the polymer resin increases and is uniformly distributed in the polylactic acid composition. However, when the average size is less than 0.5 μm, it is difficult to manufacture by a mechanical grinding process, and 500 μm. If it exceeds, the impact resistance decreases, which is not preferable.

The organic surface-treated chalcedony powder of the present invention is a fatty acid, amino acid, amide, fatty acid amide, esterified fatty acid, aliphatic amine, aromatic amine, ammonium salt, sulfonic acid (salt), sulfuric acid (salt), silane, silane coupling agent as a surface treatment agent. , Titanate coupling agents, or zirconate coupling agents may be used alone or in combination of two or more, preferably fatty acids, more preferably fatty acids having 4 to 32 carbon atoms, still more preferably stearic acid. Can be. Saturated or unsaturated fatty acids can also be used as fatty acids.

As the organic surface treatment agent, the fatty acid, amino acid, amide, fatty acid amide, esterified fatty acid, aliphatic amine, aromatic amine, ammonium salt, sulfonic acid (salt), silane or silane coupling agent preferably has 4 to 32 carbon atoms. .

0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the polylactic acid, may be included in the organic surface-treated natural stone powder, melt crystallization rate, flexural modulus, etc. There is a concern that the effect of improving mechanical properties may be insignificant, and when it exceeds 10 parts by weight, the viscosity may be increased during melt processing of the polylactic acid composition, and the impact resistance of the molded polylactic acid composition may be lowered.

The polylactic acid composition may further include an additive selected from the group consisting of antioxidants, weathering agents, mold release agents, colorants, sunscreen agents, nucleating agents, plasticizers, adhesive aids, adhesives, and mixtures thereof.

Carbon nanotubes

The content of the carbon nanotubes may be included in an amount of 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight based on 100 parts by weight of the polylactic acid, and in case of less than 0.1 parts by weight of the mechanical properties such as melt crystallization rate and flexural modulus. There is a concern that the improvement effect may be insignificant, and when it exceeds 10 parts by weight, the viscosity may be increased during melt processing of the polylactic acid composition, and the impact resistance of the molded polylactic acid composition may be lowered.

The carbon nanotubes may be single wall carbon nanotubes (SWCNTs) or multiwall carbon nanotubes (MWCNTs), but are relatively inexpensive and easy to disperse. It is preferable to use carbon nanotubes. The aspect ratio of the multi-walled carbon nanotubes may be 500 or more and the length is several micrometers (μm), but the width is on the nanometer scale.

The multi-walled carbon nanotubes are preferably at least 90% pure. In consideration of dispersibility, the carbon nanotubes may be, for example, those having an average diameter of 5 to 30 nm and a length of 1 to 20 μm.

According to the present invention, it is possible to provide a molded article made of the polylactic acid composition.

In addition, according to the present invention, the polylactic acid, organic surface-treated natural stone powder and carbon nanotubes are mixed in a solid state (a), the mixed polylactic acid, organic surface-treated natural stone powder and carbon nanotubes are melted and mixed (b) ) To prepare a polylactic acid composition in which the composition components are uniformly dispersed.

Melting and mixing (b) is preferably carried out at a temperature of 190 to 230 ℃ in a twin screw extruder.

It is preferable to dry the polylactic acid at 40 to 80 ° C. (c) before mixing (a) in the solid state, and to dry (d) the organic surface treated chalcedony powder at 110 to 150 ° C., and carbon nanotubes. It is preferable to dry (e) at 110 to 150 ° C.

The ratio of the polylactic acid, the organic surface treated chalcedony powder, the carbon nanotubes, and the composition components used in the method of preparing the polylactic acid composition is the polylactic acid, the organic surface treated chalcedony powder, and the carbon nanotubes, respectively, used in the polylactic acid composition. And the ratio of the composition components.

Hereinafter, the configuration of the present invention will be described in more detail with reference to the following examples, but is not limited thereto.

[Example]

In the following examples and comparative examples, polylactic acid was used as product name 4032D of Nature Works, and the chalcedony powder was a feldspar powder (FR-2000S, 2,000 mesh, manufactured by Chewon Co., Ltd.) surface treated with stearic acid having an average particle size of 4 μm. The carbon nanotubes were multi-walled carbon nanotubes (MWCNT SDR-3152M diameter 15 nm, purity 95%) manufactured by Empower, Inc., and β-cyclodextrin, which is generally used as a nucleating agent for thermoplastic resins, is SIGMA ALDRICH. The company's product was used. Antioxidant used 21B product of Songwon Industrial Co., Ltd.

Example  One

Polylactic acid composition was prepared by the following method according to the composition ratio of Table 1. Polylactic acid was dried in a 60 ° C. convection oven for 1 hour, and cheonmaeam powder (FR-2000S, 2,000 mesh) and carbon nanotubes treated with stearic acid having an average particle size of about 4 μm and carbon nanotubes were placed in a 130 ° C. convection oven. Dried over time.

After the drying process, 99g polylactic acid, 0.5g of aphrodite, 0.5g of carbon nanotubes and 0.2g of antioxidant were put in a mixing vessel and mixed.

99 g of mixed polylactic acid, 0.5 g of aphrodite, 0.5 g of carbon nanotubes and 0.2 g of antioxidant are added to BAUTE's BA-19 twin screw extruder (L / D = 40, 19Φ, Co-rotating) and extrusion temperature is 190 ~ 230 The mixture was mixed at 200 rpm rotation speed (about 60 seconds residence time) to prepare a polylactic acid composition in which the composition components were uniformly dispersed in a continuous process.

Example  2

A polylactic acid composition was prepared in the same manner as in Example 1, except that 97 g of polylactic acid, 1.5 g of chalcedony powder, and 1.5 g of carbon nanotubes were used.

Example  3

A polylactic acid composition was prepared in the same manner as in Example 1, except that 95 g of polylactic acid, 2.5 g of chalcedony powder, and 2.5 g of carbon nanotubes were used.

Comparative example  One

A polylactic acid composition was prepared in the same manner as in Example 1, except that 100 g of polylactic acid was used without using a cheonmaeam powder and carbon nanotubes.

Comparative example  2

A polylactic acid composition was prepared in the same manner as in Example 1, except that 99 g of polylactic acid and 1 g of feldspar powder were used without using carbon nanotubes.

Comparative example  3

A polylactic acid composition was prepared in the same manner as in Example 1, except that 97 g of polylactic acid and 3 g of feldspar powder were used without using carbon nanotubes.

Comparative example  4

A polylactic acid composition was prepared in the same manner as in Example 1, except that 95 g of polylactic acid and 5 g of feldspar powder were used without using carbon nanotubes.

Comparative example  5

A polylactic acid composition was prepared in the same manner as in Example 1, except that 99 g of polylactic acid and 1 g of carbon nanotubes were used without using a cheonmaeam powder.

Comparative example  6

A polylactic acid composition was prepared in the same manner as in Example 1, except that 97 g of polylactic acid and 3 g of carbon nanotubes were used without using a cheonmaestone powder.

Comparative example  7

A polylactic acid composition was prepared in the same manner as in Example 1, except that 95 g of polylactic acid and 5 g of carbon nanotubes were used without using a cheonmaeol powder.

Comparative example  8

A polylactic acid composition was prepared in the same manner as in Example 1 except that the cheonmaeam powder and the carbon nanotubes were not used, but instead β-cyclodextrin 1g was used.

Comparative example  9

A polylactic acid composition was prepared in the same manner as in Example 1, except that 97 g of polylactic acid and 3 g of β-cyclodextrin were used instead of the cheonmaeam powder and the carbon nanotube.

Comparative example  10

A polylactic acid composition was prepared in the same manner as in Example 1, except that 95 g of polylactic acid was used and 5 g of β-cyclodextrin was used instead of the cheonmaeam powder and the carbon nanotube.

Izod  Laminar strength ( Notched Izod Impact Strength , IS )

Five samples were prepared by compression molding the samples obtained in Examples and Comparative Examples at 200 ° C., and then subjected to ASTM D256 using an Izod impact tester (Sejin, SJTM-131) at room temperature. The average value was measured and listed in Table 2.

Flexural modulus Flexural Modulus , FM )

The samples obtained in Examples and Comparative Examples were compression molded at 200 ° C. according to their respective standards to prepare five specimens. Then, the flexural modulus was measured and averaged at room temperature using a universal testing machine. Described.

Differential Scanning Calorimetry

The sample obtained in Examples and Comparative Examples was heated to 200 ° C., about 30 ° C. higher than the melting point at a temperature rising rate of 10 ° C./min, and then maintained for 3 minutes to eliminate thermal history. Tmc was measured and ΔH was measured.

Polylactic acid
(Parts by weight) Peachstone Powder
FR2000S
(Parts by weight) Carbon nanotubes
(Parts by weight) β-cyclo
dextrin
(Parts by weight) Antioxidant
(Parts by weight) Example 1 99 0.5 0.5 0 0.2 Example 2 97 1.5 1.5 0 0.2 Example 3 95 2.5 2.5 0 0.2 Comparative Example 1 100 0 0 0 0.2 Comparative Example 2 99 One 0 0 0.2 Comparative Example 3 97 3 0 0 0.2 Comparative Example 4 95 5 0 0 0.2 Comparative Example 5 99 0 One 0 0.2 Comparative Example 6 97 0 3 0 0.2 Comparative Example 7 95 0 5 0 0.2 Comparative Example 8 99 0 0 One 0.2 Comparative Example 9 97 0 0 3 0.2 Comparative Example 10 95 0 0 5 0.2

Tmc Izod impact strength
(J / m) Flexural modulus
(MPa) peak
(℃) ΔH
(J / g) Example 1 117.26 -30.20 33 3,800 Example 2 119.63 -30.21 40 4,000 Example 3 120.57 -29.89 45 4,250 Comparative Example 1 97.03 -5.23 22 3,600 Comparative Example 2 98.58 -8.41 28 3,850 Comparative Example 3 100.01 -10.65 25 4,200 Comparative Example 4 106.38 -10.12 24 4,500 Comparative Example 5 106.89 -16.92 35 3,800 Comparative Example 6 111.48 -17.50 45 3,900 Comparative Example 7 112.20 -17.13 48 3,800 Comparative Example 8 97.33 -2.02 24 3,650 Comparative Example 9 100.02 -7.80 23 3,650 Comparative Example 10 102.59 -21.12 24 3,700

Referring to Table 1 and Table 2, it can be seen that the polylactic acid composition of the present invention has excellent impact strength, high flexural modulus, and increased Tmc (melt crystallization temperature) value, thereby increasing the crystallization rate.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Claims (19)

100 parts by weight of polylactic acid;
0.1 to 10 parts by weight of the organically treated surface of the chalcedony powder; And
0.1 to 10 parts by weight of carbon nanotubes;
Polylactic acid composition comprising. The group of claim 1, wherein the organic surface treated chalcedony powder comprises a fatty acid, an amino acid, an amide, an esterified fatty acid, an aliphatic amine, an aromatic amine, an ammonium salt, a silane, a silane coupling agent, a titanate coupling agent, and a zirconate coupling agent. Polylactic acid composition, characterized in that the organic surface treatment with at least one surface treatment agent selected from. The polylactic acid composition according to claim 2, wherein the organically treated surface of the chalcedony powder is organically surface treated with a fatty acid. The polylactic acid composition according to claim 1, wherein the organic surface-treated chalcedony powder has an average size of 0.5 to 500 µm. The polylactic acid composition according to claim 1, wherein the carbon nanotubes are at least one member selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes. The polylactic acid composition according to claim 1, wherein the polylactic acid is at least one selected from the group consisting of polylactic acid of L-optical isomer and polylactic acid of D-optical isomer. The method of claim 1, wherein the polylactic acid composition further comprises at least one additive selected from the group consisting of antioxidants, weathering agents, mold release agents, colorants, sunscreen agents, nucleating agents, plasticizers, adhesion aids, pressure-sensitive adhesives and mixtures thereof. Polylactic acid composition, characterized in that. A molded article made of the polylactic acid composition according to claim 1. (A) mixing polylactic acid, organically treated surface-treated chalcedony powder and carbon nanotubes in a solid state; And
(B) melting and mixing the mixed polylactic acid, the organic surface-treated chalcedony powder and the carbon nanotubes;
Method for producing a polylactic acid composition comprising. The method of claim 9, wherein step (b) is carried out at a temperature of 190 to 230 ℃ in a twin screw extruder. 10. The method of claim 9, further comprising drying the polylactic acid at 40 to 80 ° C. before step (a). 11. 10. The method of claim 9, further comprising the step (d) of drying the organic surface-treated chalcedony powder at 110 to 150 ° C before step (a). The method of claim 9, further comprising drying (e) the carbon nanotubes at 110 to 150 ° C. before step (a). 10. The polylactic acid composition of claim 9, further comprising: 100 parts by weight of polylactic acid; 0.1 to 10 parts by weight of the organically treated surface of the chalcedony powder; And 0.1 to 10 parts by weight of carbon nanotubes; Method of producing a polylactic acid composition comprising a. 10. The group of claim 9, wherein the organic surface treated chalcedony powder comprises a fatty acid, an amino acid, an amide, an esterified fatty acid, an aliphatic amine, an aromatic amine, an ammonium salt, a silane, a silane coupling agent, a titanate coupling agent, and a zirconate coupling agent. Process for producing a polylactic acid composition, characterized in that the organic surface treatment with at least one surface treatment agent selected from. The method for producing a polylactic acid composition according to claim 15, wherein the organically treated surface of the chalcedony powder is organically treated with fatty acid. 10. The method of claim 9, wherein the organic surface-treated chalcedony powder has a mean size of 0.5 to 500 μm. The method of claim 9, wherein the carbon nanotubes are at least one member selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes. 10. The method of claim 9, wherein the polylactic acid is at least one selected from the group consisting of polylactic acid of L-optical isomer and polylactic acid of D-optical isomer.