KR20140073337A - Resin composition of polypropylene and polylactide copolymer - Google Patents

Abstract

The present invention relates to a polypropylene-polylactide resin composition, wherein polypropylene and polylactide in which polyalkylene glycol is copolymerized are mixed, thereby having excellent compatibility and significantly improved elongation and impact strength in comparison with a conventional polypropylene even without using compatibilizers.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to polypropylene and polylactide resin compositions,

More particularly, the present invention relates to polypropylene and polylactide resin compositions, and more particularly, to a polypropylene and polylactide resin composition which is excellent in compatibility without using a compatibilizing agent by mixing a polypropylene and a polylactide copolymerized with a polyalkylene glycol, And polypropylene and polylactide resin compositions exhibiting an effect of greatly improving impact strength.

Recently, natural disasters have occurred in various parts of the world due to environmental changes caused by environmental pollution. There is a growing interest in environmentally friendly plastic used throughout the industry, and the development of non-halogen flame retardant plastics, natural fiber-reinforced plastics, and bioplastics made from plant-derived materials is being actively pursued.

Conventional and engineering plastics made from conventional petrochemicals have been used in many industrial fields such as household appliances, electrical and electronic, automobiles, etc. with excellent physical properties and low prices, and they have become an essential element in modern life. Plastics that are widely used in life and industry in general are used in a single article and parts requiring durability, and are buried or incinerated at the time of disposal.

In the case of existing petroleum-based plastics, raw materials are extracted from petroleum and produced and released to consumers. In the process from disposal to post-disposal, a large amount of CO ₂ and other greenhouse gases are released. Lt; / RTI >

Recently, there is a growing interest in the development of plastics made from plants or natural materials that can replace petroleum plastics, which have many problems such as global warming, depletion of petroleum resources, and waste problems. Eco-friendly plastics are divided into biodegradable plastics and biomass plastics. Biomass plastics are blends of petroleum plastics and bioplastics to complement the low heat resistance and durability of bioplastics.

Polyglycolic acid, polylactide, polycaprolactone, aliphatic polyester, and the like are known as bioplastics that can be used in these biomass plastics. Among them, polylactide is a polymer from lactide as a raw material of a plant, and crystalline or amorphous polylactide is produced according to the content of the optical isomer of lactide.

Polylactide (or polylactic acid or polylactic acid) is used more than 20% of total bioplastics because of its low cost and excellent physical properties compared with other bioplastics.

However, although polylactide has strong strength and rigidity, it is difficult to apply it to daily necessities, electric appliances and automobile parts because it has poor toughness, heat distortion temperature and appearance. To compensate for this, attempts have been made to blend polylactide with polypropylene, polycarbonate, acrylonitrile-butadiene-styrene, and the like.

Korean Patent Laid-Open Publication No. 2011-0116888 discloses a method of reactive compound extruding a mixture of a polyolefin, a polylactic acid and a reactive modifier to form a compatibilized polymer mixture, casting the compatibilized polymer mixture into a film form, stretching the film, And a method for producing the same.

Korean Patent Laid-Open Publication No. 2011-0025730 also discloses that a mixture of a polypropylene resin and a polylactide resin is mixed with a maleic anhydride grafted ethylene-octene copolymer and a maleic anhydride grafted polylactide, a polyethylene-glycidyl methacrylate Acrylate resin and talc particles.

However, the above-mentioned polylactide has its own weak physical properties such as hydrolysis by the catalyst used in production or factors such as moisture in the air. In particular, when polylactide or a copolymer containing the polylactide is processed into a film form and used as a disposable packaging material, it is vulnerable to shock and flexibility, and such a weakness of the water property is a great obstacle to expansion of various markets.

It is an object of the present invention to provide an environmentally friendly polylactide-polypropylene resin composition which is excellent in compatibility and is highly improved in elongation and impact strength without using a compatibilizing agent, And to provide a molded article produced therefrom.

The above object of the present invention can be achieved by the present invention described below.

According to the present invention, there is provided a polypropylene resin composition comprising: a polypropylene resin; And a polylactide copolymer in which a polyalkylene glycol is copolymerized. The present invention also provides a polylactide-polypropylene resin composition.

The present invention also provides a molded article made of the polylactide-polypropylene resin composition.

As described above, according to the present invention, when polylactide copolymerized with polyalkylene glycol is mixed with polypropylene, compatibility with polypropylene is excellent, and elongation and impact strength are greatly improved without using a compatibilizer.

1 is an SEM photograph of a polylactide-polypropylene resin composition specimen prepared in Examples and Comparative Examples of the present invention.
2 is a graph showing tensile strength of polylactide-polypropylene resin composition specimens prepared in Examples and Comparative Examples of the present invention.
3 is a graph showing elongation of polylactide-polypropylene resin composition specimens prepared in Examples and Comparative Examples of the present invention.
4 is a graph showing the impact strength of polylactide-polypropylene resin composition specimens prepared in Examples and Comparative Examples of the present invention.
5 is a ¹ H NMR spectrum of the lactide copolymer of Example 1 of the present invention.

In order to achieve the above object, the present invention provides a polypropylene resin composition, And a polylactide copolymer in which a polyalkylene glycol is copolymerized with the polylactide-polypropylene resin composition.

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

The present invention relates to a polypropylene resin and a polylactide mixture, and has excellent compatibility when mixing polylactide copolymerized with polyalkylene glycol and polypropylene, and improves elongation and impact strength. The polylactide-polypropylene resin composition according to the present invention is a polylactide-polypropylene resin composition containing 25% by weight or more of polylactide, which is a biodegradable material, to replace low-carbon and green growth by replacing polypropylene with disposable products, cosmetics, have.

The polylactide-polypropylene resin composition does not contain a compatibilizing agent or is contained in a small amount. Generally, polypropylene and polylactide are very poor in compatibility, and therefore, they have disadvantages in that desired physical properties can be realized only when a high-cost compatibilizing agent is added. However, according to the present invention, polylactide copolymerized with polyalkylene glycol is mixed with polypropylene It is possible to obtain a result that the compatibility is excellent and the elongation and impact strength are greatly improved even without using a compatibilizing agent.

The polylactide copolymer of the present invention has excellent compatibility with general polylactide and thus has a relatively small domain. The SEM measurement result shows that the matrix is a polypropylene resin and the domain is a polylactide copolymer and the copolymer is formed in a circular shape. The smaller the size is, the more dispersed the surface area becomes, It becomes. Unlike the general purpose polylactide in which the use of a compatibilizing agent is essential, the polylactide-polypropylene resin composition in which the polyalkylene glycol is copolymerized according to the present invention increases the input amount of the compatibilizing agent, The change in the domain size of the compatibilizer is insignificant and the correlation between the amount of the compatibilizer and the compatibility is small.

In conclusion, the polyalkylene glycol-copolymerized polylactide copolymer in the present invention makes the polylactide copolymer domain small in the polypropylene without adding an expensive compatibilizer, thereby improving the elongation and impact strength.

The polypropylene resin may be, for example, 50 to 75% by weight, 55 to 75% by weight, or 55 to 72% by weight. When the content of the propylene-based resin is within the above-mentioned range, there is an effect of excellent elongation and impact strength.

The polylactide may be selected from the group consisting of poly-L-lactide, poly-D-lactide, poly L, and D-lactide having a weight average molecular weight of 100,000 or more. The polylactide used in the present invention may be one having a high optical purity of lactide, preferably poly L-lactide having an optical purity of 85% or more, more preferably poly L-lactide having an optical purity of 95% . If the optical purity is high, the heat resistance and crystallization rate of the resin composition can be increased.

The content of the polylactide copolymer used in the present invention is 25 to 50% by weight, 25 to 45% by weight, or 28 to 45% by weight based on 100% by weight of the resin composition. Within this range, the use of a vegetable resin is effective, and overall physical properties such as elongation, impact resistance, and workability are improved.

The polyalkylene glycol may have a number average molecular weight of 1,000 to 15,000, 2,000 to 13,000, or 3,000 to 10,000, for example. By including polyalkylene glycols having such a large molecular weight in this range, the polylactide copolymer can exhibit and maintain excellent flexibility and exhibit improved mechanical properties.

The polylactide copolymer may be represented by the following general formula (1).

Wherein D is a linear or branched alkylene group having 2 to 10 carbon atoms, x is independently an integer of 30 to 500, and n is an integer of 30 to 1000.

As another example, the polylactide copolymer may be prepared by copolymerizing 5 to 50% by weight or 10 to 40% by weight of polyalkylene glycol with 50 to 95% by weight or 60 to 90% by weight of lactic acid, lactic acid anhydride or a derivative thereof . Within this range, the mechanical properties of the lactide copolymer are greatly improved.

The polylactide copolymer may have a weight average molecular weight of 50,000 to 500,000, 75,000 to 450,000, or 80,000 to 400,000, for example. A polylactide copolymer having a weight average molecular weight within this range is suitable for molding because of its sufficient physical properties and flow characteristics, and has an excellent compatibility with a polypropylene resin and excellent processability.

Wherein the polylactide copolymer comprises two or more block copolymerized repeating units of the formula (1), wherein the hard segment of the polylactide repeating unit is bonded to both ends of the soft segment of the polyalkylene glycol repeating unit, Units are linked together via a urethane linking group derived from a polyisocyanate compound having an average isocyanate group equivalent of 2 or more or a polyisocyanate compound having a polyisocyanate compound having a number of 2 or more and 3 or less.

The method for producing the polylactide copolymer includes ring-opening polymerization of a lactide monomer in the presence of an initiator containing a tin or zinc catalyst and a polyalkylene glycol to form a block copolymer represented by the following formula (2); And a block copolymer of the formula (2) with a polyisocyanate compound having an average isocyanate group average molecular weight per molecule of 2 or more or a polyisocyanate compound having an average of 2 or more and less than 3.

Wherein D is a linear or branched alkylene group having 2 to 10 carbon atoms, x is independently an integer of 30 to 500, and n is an integer of 30 to 1000.

The lactide copolymer includes a block copolymer repeating unit of the above formula (1) wherein the hard segment of the polylactide repeating unit is bonded to both ends of the soft segment of the polyalkylene glycol.

Such a block copolymerization repeating unit is contained in the copolymer in a plurality of two or more, and these copolymer repeating units are connected to each other via a urethane linking group. Wherein the urethane linking group is derived from a polyisocyanate compound having an average number of isocyanate groups per molecule of 2 or more or a polyisocyanate compound having a polyisocyanate compound having a polyisocyanate compound having a polyisocyanate compound having an average of isocyanate groups of 2 or more and less than 3, Lt; RTI ID = 0.0 > urethane bonds < / RTI >

As the block copolymer units have a structure linked to each other by a urethane linkage, that is, a polyisocyanate compound having an equivalent number of isocyanate groups per molecule of 2 or more or a polyisocyanate compound having more than 2 and less than 3, It can have a higher molecular weight even under the same polymerization conditions, and can have excellent mechanical properties accordingly. Also, due to this linkage structure, the molecular weight of the lactide copolymer and thus the control of the physical properties thereof can be made easier.

The polyisocyanate compound for forming such a urethane linking group has a diisocyanate compound having an isocyanate group equivalent of 2 and a diisocyanate compound having an equivalence of isocyanate groups of 3 or more in order to satisfy the above- The compounds may be included in admixture form or the like.

Specific examples of the diisocyanate compound include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,2-dodecane diisocyanate, cyclohexane- Diisocyanate, cyclohexane-1,4-diisocyanate, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, hexahydro-1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, perhydro-2,4-diphenylmethane diisocyanate, perhydro-4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, , 4-phenylenediisocyanate, 1,4-stilbene diisocyanate, 3,3'-dimethyl-4,4'-diphenylenediisocyanate, toluene-2,4-diisocyanate (TDI) , 6-diisocyanate, diphenylmethane-2,4'-di (MDI), diphenylmethane-2,2'-diisocyanate, diphenylmethane-4,4'-diisocyanate or naphthalene-1,5-diisocyanate, and the equivalent of the isocyanate group is Examples of the polyvalent isocyanate compound having 3 or more include an oligomer of the diisocyanate compound, a polymer of the diisocyanate compound, a cyclic oligomer of the diisocyanate compound, hexamethylene diisocyanate isocyanurate, a triisocyanate compound And isomers thereof, and the like.

The polyalkylene glycol in the block copolymerized repeating units of the lactide copolymer may have a number average molecular weight of 1,000 to 15,000, 2,000 to 13,000, or 3,000 to 10,000, for example. By including polyalkylene glycols having such a large molecular weight in this range, the polylactide copolymer can exhibit and maintain excellent flexibility and exhibit improved mechanical properties. The polyalkylene glycol may be selected from the group consisting of, for example, polyethylene glycol, poly (1,2-propylene glycol), poly (1,3-propanediol), polytetramethylene glycol and polybutylene glycol.

The polypropylene resin may be a polypropylene polymer or a copolymer of a polypropylene and an aliphatic alpha-olefin or an aromatic olefin. Wherein the aliphatic alpha-olefins and aromatic olefins may have from 2 to 20 carbon atoms, preferably from 2 to 8 carbon atoms.

For example, the polypropylene resin may be a polypropylene polymer or a copolymer of propylene and at least one olefin selected from the group consisting of ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene, As another example, at least one selected from the group consisting of polypropylene polymer, polypropylene copolymer, propylene-alpha-olefin copolymer, propylene-ethylene copolymer, propylene-butene copolymer and propylene-ethylene-butene copolymer is used . Where the copolymer may be a random or block copolymer.

In the present invention, the polypropylene resin may have a melt flow index of 0.1 to 10 g / 10 min or 0.1 to 0.8 g / 10 min measured at 230 ° C and 2.16 kg under ASTM D1238. Within this range, the flow index of the poly (lactic acid-polypropylene) resin composition is suitable for the flow viscosity of the parison for blow molding, and the molding proceeds smoothly.

As another example, the polylactide-polypropylene composition of the present invention may contain less than 2.5 parts by weight, 0.001 to 2 parts by weight, or 0.5 to 5 parts by weight, based on 100 parts by weight of the total amount of the polypropylene resin and the polylactide copolymer, 1.5 parts by weight. Within this range, there is an excellent effect of elongation and impact strength. The compatibilizing agent may be, for example, an ethylenic compatibilizer.

The present invention also provides a molded article produced by molding the polylactide-polypropylene resin composition.

The molding may be performed by extrusion or blow molding of a polylactide-polypropylene resin composition. The molded article may be a sheet or a film. As another example, the polylactide-polypropylene resin composition of the present invention can be used as a packaging container, a household goods container, or an industrial material part, which is manufactured in a single layer or a multi-layer, in particular, by blow molding.

The polylactide-polypropylene resin composition of the present invention can also be used in combination with other additives such as antioxidants, UV stabilizers, lubricants, hydrolysis stabilizers, metal deactivators, pigments, colorants, antistatic agents, conductivity imparting agents, EMI shielding agents, An antimicrobial agent, a processing aid, an anti-friction abrasive agent, and the like. The above-mentioned various additives can be used within a range that does not adversely affect the physical properties according to the present invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Changes and modifications may fall within the scope of the appended claims.

[Example]

Example  One

Polylactide  Preparation of Copolymer

(1.0 mmol) of Sn (Oct) ₂ (0.2 g, 0.49 mmol, manufacturer: Aldrich) and a compound of the following formula (TCI: manufacturer: TCI) were added to a 100 mL flask, 30 mL of toluene was added thereto, Lt; / RTI > The solvent was then removed under vacuum, washed with heptane solvent and dried to yield 0.36 g of the organometallic complex.

Subsequently, 100 kg (693.82 mol) of L-lactide monomer and 102.81 g of the organometallic complex prepared above were charged into a 150 L reactor equipped with a nitrogen introduction pipe, a stirrer, a catalyst inlet and a vacuum system, Average molecular weight: 6,000 g / mol) were charged and subjected to ring-opening polymerization at a temperature of 180 ° C for 3 hours to prepare a block copolymer of the formula (2). A part of the polymer resin was sampled in the reactor and the weight average molecular weight was measured using GPC (Gel Permeation Chromatography). The weight average molecular weight (Mw) was 95,000.

Thereafter, a polyisocyanate compound having an equivalent number of isocyanate groups per molecule of about 2.7 (a mixture of MDI having an isocyanate group equivalent of 2.0 and hexamethylene diisocyanate isocyanurate having an equivalence of isocyanate groups of 3.0) ) Was added thereto, and the resultant was subjected to addition polymerization reaction with the block copolymer of Formula 2 at 180 ° C for 30 minutes to form a urethane linking group.

After the completion of the reaction, the residual lactide is removed through a conventional volatilization process to produce a lactide copolymer of the formula (1). The lactide copolymer thus prepared has a content of repeating units of polylactide and polyether polyol (wt %), Weight average molecular weight, polydispersity index, glass transition temperature and melt temperature were measured. As a result of the measurement, the contents of polylactide and polyalkylene glycol repeating units in the block copolymerization repeating units were 85 wt% and 15 wt%, respectively, and Mw = 244,000, polydispersity index = 2.57, Tg = 48 캜, and Tm = 169 Lt; 0 > C. The ¹ H NMR spectrum of the prepared lactide copolymer is as shown in Fig.

Polylactide - Polypropylene series  Preparation of resin composition

120 g of a polylactide copolymer (LG Chem) and 280 g of polypropylene (PP, M1400, LG Chem) were first mixed in a super mixer and then kneaded in a twin-screw extruder (BAUTEK L40 / D19 Twin Screw 19Φ) Was extruded by melt-kneading under the following conditions.

Zone Head One 2 3 4 5 6 7 Screw speed (rpm) Feeder speed (rpm) Temperature (℃) 220 220 220 220 210 195 170 150 150 2.4

After final pelletization, specimens were prepared under the following conditions.

- HAADE MiniJet - Micro Injection Molding Tensile bar according to ASTM D638 Type V

- Cylinder 220 캜, Mold 70 캜, Pressure 400 bar

Example  2

In Example 1, 120 g of a polylactide copolymer (LG Chem), 280 g of polypropylene (PP, M1400, LG Chem) and 3 g of an ethylene-based compatibilizer containing a glycidyl methacrylate (compatibilizer, The specimens were prepared in the same manner as in Example 1 except for the following.

Example  3

Except that 120 g of the polylactide copolymer (LG Chem), 280 g of polypropylene (PP, M1400, LG Chem) and 5 g of compatibilizer (universal compatibilizer) were mixed in Example 1, Specimens were prepared by the same method.

Example  4

Except that 120 g of the polylactide copolymer (LG Chem), 280 g of polypropylene (PP, M1400, LG Chem) and 10 g of compatibilizer (universal compatibilizer) were mixed in Example 1, Specimens were prepared by the same method.

Comparative Example  One

A specimen was prepared in the same manner as in Example 1, except that the polylactide copolymer (LG Chem) was replaced with a general polylactide (4032D, Nature Works).

Comparative Example  2

A specimen was prepared in the same manner as in Example 2, except that a general polylactide (4032D, Nature Works) was used instead of the polylactide copolymer (LG Chem) in Example 2.

Comparative Example  3

A specimen was prepared in the same manner as in Example 3, except that a general polylactide (4032D, Nature Works) was used instead of the polylactide copolymer (LG Chem) in Example 3.

Comparative Example  4

A specimen was prepared in the same manner as in Example 4, except that a general polylactide (4032D, Nature Works) was used instead of the polylactide copolymer (LG Chem) in Example 4.

[Test Example]

The physical properties of the samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were measured by the following methods, and the results are shown in Table 2 below.

[Measurement of physical properties]

* Tensile strength and elongation: measured according to ASTM D638 method.

* Notched Izod: Impact strength: Measured at room temperature (23 ° C) after notching in 1/8 inch thick specimens according to ASTM D256 method.

It can be seen that the polylactide-polypropylene resin compositions prepared according to Examples 1 to 4 of the present invention are much more excellent in elongation than Comparative Examples 1 to 4. The impact strength similar to that obtained by adding 3 wt% of the compatibilizing agent as in Comparative Example 2 could be achieved without using the compatibilizer at all. When the content of the compatibilizer is increased in Examples 2 to 4, the elongation and impact strength increase and the tensile strength tends to decrease as shown in FIG. 2, as shown in FIGS. 3 and 4.

In addition, FIG. 1, which is an analysis of the SEM shape according to the amount of the compatibilizer, shows that when the compatibilizing agent is not present, the polylactide copolymer is more compatible with the general polylactide, Could.

In the case of the polylactide copolymer, the change of the domain size of the polylactide copolymer is insignificant even if the amount of the compatibilizing agent is increased. Therefore, it is considered that the amount of the compatibilizer is not correlated with the compatibility with the compatibilizer. However, in the case of the general polylactide, the use of the compatibilizing agent is essential because the polylactide domain is very small when the third, fifth, and 10 wt% of the compatibilizing agent is added.

In conclusion, the polylactide copolymer of the present invention can be made to have a small polyolectide copolymer domain in polypropylene without adding an expensive compatibilizing agent, thus making the extrusion molding machine excellent in elongation and impact strength.

Claims (10)

Polypropylene type resin; And
Wherein the polylactide-polypropylene resin composition comprises a polylactide copolymer in which a polyalkylene glycol is copolymerized.
The method according to claim 1,
The polylactide-polypropylene resin composition contains no compatibilizing agent or is contained in an amount of less than 2.5 parts by weight based on 100 parts by weight of the polylactide copolymer having polypropylene resin and polyalkylene glycol copolymerized By weight based on the total weight of the polylactide-polypropylene resin composition.
The method according to claim 1,
Wherein the propylene resin is 50 to 75% by weight, and the polyalkylene glycol-copolymerized polylactide copolymer is 25 to 50% by weight.
The method according to claim 1,
Wherein the polylactide copolymer comprises 5 to 50% by weight of a polyalkylene glycol; And 50 to 95% by weight of lactic acid, lactic acid anhydride or a derivative thereof are copolymerized with the polylactide-polypropylene resin composition.
The method according to claim 1,
The polylactide-polypropylene resin composition according to claim 1, wherein the polylactide copolymer is represented by the following formula (1).
[Chemical Formula 1]

Wherein D is a linear or branched alkylene group having 2 to 10 carbon atoms, x is independently an integer of 30 to 500, and n is an integer of 30 to 1000.
The method according to claim 1,
Wherein the polylactide copolymer has a weight average molecular weight of 50,000 to 500,000.
The method according to claim 1,
Wherein the polypropylene resin is a polypropylene polymer or a copolymer of a polypropylene and an aliphatic alpha-olefin or an aromatic olefin.
The method according to claim 1,
Wherein the polyalkylene glycol has a number average molecular weight of 1,000 to 15,000.
A polylactide-polypropylene-based molded article produced by molding the polylactide-polypropylene resin composition of claim 1.
10. The method of claim 9,
Wherein the molded article is a sheet or a film.

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