KR20090072832A - Biodegradable resin composition - Google Patents

Abstract

A biodegradable resin composition is provided to ensure fast crystallization rate compared with conventional polylactic acid, high crystallization degree, and excellent mechanical property including heat resistance and impact strength. A biodegradable resin composition comprises (A) a base resin compound and (B) a diisocyanate compound 1-4 parts by weight based on the base resin composition 100.0 parts by weight. The base resin compound(A) comprises a polylactic acid resin 30-60 weight%, a polyalkylene terephthalate resin 15-35 weight%, a thermoplastic polyester elastomer resin 10-20 weight% and a nucleating agent 10-20 weight%. The biodegradable resin composition includes antioxidant, lubricant or their mixture of 0.01-1 parts by weight based on the base resin compound 100.0 parts by weight.

Description

Biodegradable Resin Composition {BIODEGRADABLE RESIN COMPOSITION}

The present invention relates to a biodegradable resin composition having excellent heat resistance and impact strength, and more particularly, based on conventional polylactic acid (PLA), polyalkylene terephthalate, thermoplastic polyester elastomer, nucleating agent and The present invention relates to a biodegradable resin composition including diisocyanate, which has high crystallization rate, high crystallinity, good productivity during injection molding, and improved heat resistance and impact strength of molded articles.

In the past decades, plastics have increased rapidly due to their convenience, stability and low cost, but plastics are hardly decomposed in their natural state, causing serious environmental problems caused by plastic waste. Therefore, the development of eco-friendly biodegradable polymer materials has emerged all over the world, and many products have been commercialized.

In general, polylactic acid, an aliphatic polyester, has been used for various purposes because of its biodegradability and mechanical properties, and recently, it can be used for a wide range of applications such as automobile parts, electronic materials, and packaging materials. Is getting. However, since the crystallization rate is relatively slow when molding compared to other polymer materials, there is a disadvantage in that the moldability is lowered and the physical properties of the molding are lowered when used alone.

In order to solve this problem, a method of improving the crystallization rate of the melt by adding a small amount of nucleation agent to the existing polylactic acid has been studied. However, such a nucleating agent alone is not sufficient to improve the crystallization rate, and still has problems in heat resistance and impact strength for use in engineering plastics.

Accordingly, the present invention is to provide a biodegradable resin composition that can be used as engineering plastics because the crystallization rate is faster than the existing polylactic acid resin and the crystallinity is high and the mechanical properties such as heat resistance and impact strength are excellent. do.

In order to achieve the above object, the present invention is a polylactic acid (PLA) resin, a polyalkylene terephthalate resin, an impact modifier to a thermoplastic polyester elastomer (TPEE), a nucleating agent and a diisocyanate that can react with the terminal of the polymer It provides a biodegradable resin composition comprising.

The eco-friendly polylactic acid / polyalkylene terephthalate composite material of the present invention has an effect of improving heat resistance and impact strength by reacting extrusion by adding a diisocyanate compound and a thermoplastic polyester elastomer together. In addition, the present invention has an effect of increasing the productivity of the biodegradable resin by reducing the cycle time by increasing the crystallization rate of the polylactic acid is a slow crystallization rate during injection molding. In addition, the biodegradable resin composition of the present invention has excellent thermal stability and mechanical properties as compared to the conventional polylactic acid resin, and thus has the possibility of application to not only general purpose plastics but also engineering plastics such as automobile materials and electric / electronic materials.

Hereinafter, the present invention will be described in detail.

The present invention (A) 30 to 60% by weight of polylactic acid (PLA) resin, 15 to 35% by weight of polyalkylene terephthalate resin, 10 to 20% by weight of thermoplastic polyester elastomer (TPEE) resin and 10 to 20 nucleating agent A base resin composition comprising weight percent; And (B) 1 to 4 parts by weight of the diisocyanate compound based on 100 parts by weight of the resin composition.

The present invention uses polylactic acid (PLA) resin as the biodegradable resin of the resin composition. In the present invention, the polylactic acid resin preferably has a molecular weight of 10,000 to 200,000. If the molecular weight of the polylactic acid resin is less than 10,000, there is a problem in thermal and mechanical properties, and if it exceeds 200,000, a lot of energy is required for processing and the crystallization rate may be reduced. In the present invention, the polylactic acid resin is included in the basic resin composition 30 to 60% by weight, preferably 35 to 55% by weight, more preferably 40 to 50% by weight. If the polylactic acid resin is contained in less than 30% by weight in the basic resin composition, the degree of biodegradation in the natural state is slow, and when included in excess of 60% by weight, the crystallization rate is low, there is a problem that the cooling time during injection is long.

The composition of the present invention comprises a polyalkylene terephthalate resin. Polyalkylene terephthalate resin is relatively easy to crystallize compared to polylactic acid resin, and can accelerate the crystallization rate of the composition of the present invention. The polyalkylene terephthalate which can be used in the present invention includes, for example, polybutylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, and the like, preferably polyethylene terephthalate, polybutylene terephthalate, and more. Preferably it is polybutylene terephthalate. In the present invention, the polyalkylene terephthalate resin is included in the basic resin composition 15 to 35% by weight, preferably 20 to 32% by weight, more preferably 25 to 30% by weight. In the present invention, when the polyalkylene terephthalate resin is included in the base resin composition in less than 15% by weight, there is a problem in accelerating the crystallization rate of the polylactic acid, and when included in excess of 35% by weight, it does not decompose in nature. There is.

The composition of the present invention comprises a thermoplastic polyester elastomer (TPEE). The thermoplastic polyester elastomer used in the present invention preferably has a Shore hardness of about 30 to 50, and having a Shore hardness in this range can simultaneously improve the heat resistance and impact strength of the composition. In the present invention, the thermoplastic polyester elastomer is included in the base resin composition 10 to 20% by weight, preferably 12 to 18% by weight. In the present invention, when the thermoplastic polyester elastomer is included in the base resin composition in less than 10% by weight, a problem in impact resistance occurs, and when included in excess of 20% by weight, the crystallization rate is lowered, thereby causing a problem in heat resistance.

The composition of the present invention includes a nucleating agent. Nucleating agents that can be used in the present invention include, for example, mica, talc, silica, calcium carbonate, clay and cellulose fibers (including wood flour), Preferably it is talc, calcium carbonate, mica, More preferably, it is mica. In the composition of the present invention, the nucleating agent not only serves to form a nucleus so that crystallization can easily occur, but also serves to enhance mechanical properties as a reinforcing agent. In the present invention, the nucleating agent is included in the base resin composition 10 to 20% by weight, preferably 12 to 18% by weight. If the nucleating agent is included in the base resin composition in less than 10% by weight in the present invention, there is a problem that the crystallization rate is slowed down because the nucleation effect is lowered, and when the nucleating agent is included in excess of 20% by weight, raw material is not smoothly injected during extrusion. There is a problem that mechanical properties such as impact resistance is inferior.

The biodegradable resin composition of the present invention includes a diisocyanate compound, and preferably includes a diisocyanate compound represented by the following Formula 1 to generate a chemical bond between polymers during reaction extrusion.

O = C = NR ¹ -N = C = O

In Formula 1, R ¹ is C ₁ -C ₂₀ alkylene, C ₆ -C ₂₀ arylene, C ₃ C ₂₀ cyclo

Alkylene, C ₈ -C ₂₀ arylalkylene or C ₇ -C ₂₀ alkylarylene.

When the isocyanate is included in the biodegradable composition of the present invention, as the miscibility is increased through chemical bonding between the polymers, the flow rate of the molten state may be improved as well as the crystallization rate may be accelerated. The nucleating agent in the composition of the present invention provides a nucleating effect, thereby facilitating nucleation, and further accelerating the crystallization rate of polyethylene terephthalate, which is relatively easy to crystallize, thereby accelerating the crystallization of polylactic acid bound by chemical bonds. In addition to the increase in the molecular weight of the resin composition through the reaction extrusion may be a driving force to form crystals by helping the movement of the polymer chain due to the increase in the molecular weight distribution.

When the diisocyanate of Chemical Formula 1 is included in the biodegradable resin composition of the present invention, polylactic acid, polyethylene terephthalate, and thermoplastic polyester elastomer are bonded by a linking unit represented by the following Chemical Formula 2 through reaction extrusion.

Poly (lactic acid) -O- [CONH-R ¹ -NHOC] -O- Poly (lactic acid)

Poly (lactic acid) -O- [CONH-R ¹ -NHOC] -O-Polyester

Polyester-O- [CONH-R ¹ -NHOC] -O-Polyester

In Formula 1, R ¹ is C ₁ -C ₂₀ alkylene, C ₆ -C ₂₀ arylene, C ₃ C ₂₀ cycloal chelene, or C ₈ -C ₂₀ arylalkylene.

The biodegradable resin composition of the present invention contains 1 to 4 parts by weight of the diisocyanate compound based on 100 parts by weight of the basic resin composition including the polylactic acid resin, the polyalkylene terephthalate resin, the thermoplastic polyester elastomer resin and the nucleating agent. More preferably 2 to 3 parts by weight. When the diisocyanate compound is included in less than 1 part by weight of the composition of the present invention, the degree of acceleration of the crystallization rate is insignificant, and when it is included in excess of 4 parts by weight, no further increase in crystallization rate can be expected and there is a problem that only the manufacturing cost increases. Can be.

The composition of the present invention may optionally contain additives to improve physical properties. Such additives are, for example, antioxidants, lubricants or mixtures thereof. If used, the additive is included 0.01 to 1 parts by weight based on 100 parts by weight of the base resin composition comprising the polylactic acid resin, polyalkylene terephthalate resin, thermoplastic polyester elastomer resin and nucleating agent of the present invention 0.01 weight If it is included in less than a part, it may not exhibit sufficient effects of the additive, and even if added in excess of 1 part by weight, no further increase in effect can be expected and only the manufacturing cost increases.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only for illustrating the present invention, and the present invention is not limited by the examples.

material

Polylactic Acid (PLA): NatureWorks, 4032D

Polybutylene terephthalate (PBT): Samyang Corporation, TRIBIT 1300

Thermoplastic Polyester Elastomer (TPEE): Samyang Corp., TRIEL 5400

Mica: Kuraray 400 W

All the materials were used after drying for 5 hours at 80 ℃.

Diisocyanate compounds: Dupont, p-phenylene diisocyanate (PPDI)

Antioxidants: Songwon Industry, Songnox1010; Ciba specialty chemicals, Seenox412s; Great Lakes chemical, Alkanox240

Lubricant: Loxiol EP861

Comparative example  1 to 8 and Example  One

The composition of Comparative Examples 1 to 8 and Example 1 were mixed using the twin screw extruder according to the contents shown in Table 1, followed by extrusion processing, followed by injection drying at a processing temperature of 240 ° C. after vacuum drying at 80 ° C. for 4 hours. .

Property measurement

Heat Deflection Temperature Measurement

In order to measure the heat resistance characteristics of the resin compositions prepared according to Comparative Examples 1 to 8 and Example 1, a specimen was prepared by injection molding, and an ASTM D638 method was performed using a heat distortion temperature (HDT) tester (TOYOSEIKI, 6M-2). According to the heat deformation temperature was measured by 4.6kg / cm ² load.

Impact strength measurement

In order to measure the impact strength of the resin compositions prepared according to Comparative Examples 1 to 8 and Example 1 by injection molding to prepare a specimen notched cut by the ASTM D256 method, an impact tester (CEAST, IT-98) The impact strength was measured using.

The results obtained from the heat deflection temperature and impact strength measurements are summarized in Table 2 below.

Preliminary experiments were carried out to determine the optimum content of mica for the nucleation effect and physical properties reinforcement of polylactic acid, and then blended with polybutylene terephthalate having a relatively high crystallization rate, as shown in Comparative Example 3 of Table 2 above. The heat deflection temperature showed only a slight synergistic effect of about 3 ℃. 1, 3, 5 parts by weight of p-phenylene diisocyanate capable of reacting with polymer chain ends in a polylactic acid / polybutylene terephthalate / mica mixture to raise the heat deformation temperature to 100 ° C. or more (Comparative Examples 6 to 6). 8) was mixed by the content of the extrusion process. As can be seen from the results of Comparative Examples 6 to 8 of Table 2, when 3 parts by weight or more of p-phenylene diisocyanate was added, the heat deformation temperature was 140 ° C. or higher, which was higher than that of Comparative Example 3, and p- As the content of phenylene diisocyanate increases, the heat distortion temperature increases so that the reaction extrusion of p-phenylene diisocyanate is effective to increase the heat deformation temperature of the polylactic acid mixture. To 3 parts by weight. This is due to chemical bonding of homogeneous polymer or heteropolymer chain ends through reaction extrusion of p-phenylene diisocyanate, which accelerates crystallization rate by rapid nucleation, and facilitates chain movement by widening molecular weight distribution. It was judged because

As can be seen in Comparative Example 7 and Comparative Example 8 of the impact strength, the impact strength was slightly reduced rather than before the reaction extrusion process using p-phenylene diisocyanate. Therefore, in order to simultaneously improve heat resistance and impact strength, 15% by weight of thermoplastic polyester elastomer (Example 1) was added as an impact modifier. As shown in Table 2, Example 1 can reduce the heat deflection temperature to 105 ℃ and increase the impact strength to 5.6kgf / cm ² was determined to be effective in increasing the impact strength of the polylactic acid mixture. This was determined because the thermoplastic polyester elastomer of the polyester system can be effectively dispersed in the matrix of the polylactic acid mixture.

Claims (6)

(A) 30 to 60% by weight of polylactic acid (PLA) resin, 15 to 35% by weight of polyalkylene terephthalate resin, 10 to 20% by weight of thermoplastic polyester elastomer (TPEE) resin and 10 to 20% by weight of nucleating agent Basic resin composition containing; And (B) 1 to 4 parts by weight of the diisocyanate compound based on 100 parts by weight of the base resin composition. The resin composition according to claim 1, further comprising 0.01 to 1 parts by weight of an antioxidant, a lubricant, or a mixture thereof, based on 100 parts by weight of the base resin composition (A). The resin composition according to claim 1, wherein the polyalkylene terephthalate is at least one selected from polybutylene terephthalate, polyethylene terephthalate and polytrimethylene terephthalate. The composition of claim 1, wherein the nucleating agent is at least one selected from mica, talc, silica, calcium carbonate, clay, and cellulose fibers. . The composition of claim 1, wherein the diisocyanate compound is p-phenylene diisocyanate. Biodegradable resin composition wherein a polylactic acid resin, a polyalkylene terephthalate, and a thermoplastic polyester elastomer resin are bonded by a linking unit represented by the following general formula (2): [Formula 2] Poly (lactic acid) -O- [CONH-R ¹ -NHOC] -O- Poly (lactic acid) Poly (lactic acid) -O- [CONH-R ¹ -NHOC] -O-Polyester Polyester-O- [CONH-R ¹ -NHOC] -O-Polyester In the above formula, R ¹ is C ₁ -C ₂₀ alkylene, C ₆ C ₂₀ arylene, C ₃ C ₂₀ cycloalkylene, C ₈ -C ₂₀ arylalkylene, or C ₇ -C ₂₀ alkylarylene.