KR20110068478A - Polypropylene resin composition having ultra high transparency and the molded article - Google Patents

Abstract

PURPOSE: A polypropylene resin composition having ultra high transparency is provided to ensure excellent transparency and to minimize unpleasant odor of molded articles. CONSTITUTION: A polypropylene resin composition comprises (a) 100.0 parts by weight of ethylene-propylene random copolymers in which the ethylene content is 3.5-8.0 weight%, (b) 0.1-0.6 parts by weight of dibenzylidene nonitol-based nucleating agents, and (c) 0.005-0.01 parts by weight of amorphous silica. The average particle size of the polypropylene resin composition is 150 micron or less.

Description

Ultra-high transparency polypropylene resin composition and molded article thereof {POLYPROPYLENE RESIN COMPOSITION HAVING ULTRA HIGH TRANSPARENCY AND THE MOLDED ARTICLE}

The present invention relates to an ultra-transparent polypropylene resin composition and a molded article produced therefrom, and more particularly, to have excellent transparency and higher specificity than the existing polyethylene terephthalate (PET) resin and polycarbonate (PC) resin, and in terms of specific gravity, etc. It relates to an ultra-transparent polypropylene resin composition and a molded article produced therefrom which can secure improved physical properties.

Conventionally, transparent plastic containers use PET resin or polycarbonate resin through injection, stretch blow molded products, and direct blow molding, but all of these resins have a specific gravity of 1.2 or more, which is heavy, relatively expensive, and recently, Since it is not suitable for reducing petrochemical resources, new materials are required. In particular, there is a research result that polycarbonate, which is recently used as a baby bottle, releases environmental hormone substances harmful to human body at high temperature disinfection, and there is an urgent need for development of alternative materials.

In general, polypropylene resins are used in a wide range of applications, including food containers and pharmaceutical containers, because they are excellent in chemical properties, physical properties and molding processability and inexpensive. However, since polypropylene resin itself does not necessarily have sufficient transparency and mechanical strength characteristics, a method of improving transparency and mechanical strength characteristics is usually adopted by adding various nucleating agents to the resin.

For example, when a random copolymer is prepared through copolymerization with monomers such as ethylene and butene, the crystallinity is lowered, and a nucleating agent is added thereto to reduce the crystal grain size, thereby providing excellent transparency. As a result, its application is rapidly increasing. However, as the ethylene content increases, the stereoregularity becomes weaker, thereby improving transparency. However, in the bulk system process, which is a manufacturing process of most polypropylene, the productivity is sharply lowered when 3% or more is added. Extraction increases with such productivity decreases, which causes various problems in molding a product.

On the other hand, even if the nucleating agent or sorbitol nucleating agent of the organic phosphate ester metal salt type commonly used to improve the transparency as a nucleating agent, polyethylene terephthalate (PET) resin and polycrystalline resin, which is an amorphous resin due to the crystallinity of the polypropylene resin itself Clear clarity cannot be obtained than carbonate (PC) resin. In addition, if the content of the nucleating agent is increased, the transparency is increased, but there is a problem that the smell becomes severe and the dispersibility is poor when mixed with the polypropylene.

Therefore, it is possible to secure excellent transparency that is equivalent to or higher than that of the existing amorphous resins, such as polyethylene terephthalate (PET) resin and polycarbonate (PC) resin, and at the same time, there is no unpleasant odor when using the product. There is a need for research on the development of ultra-high transparency polypropylene resin compositions that do not cause a decrease in productivity.

The present invention is to provide an ultra-transparent polypropylene resin composition that is excellent in transparency and can minimize productivity degradation during product manufacturing and unpleasant odor in the final product.

Another object of the present invention is to provide a molded article having excellent transparency and almost no unpleasant odor generation.

The present invention comprises a) 100 parts by weight of an ethylene-propylene random copolymer having an ethylene content of 3.5 to 8.0% by weight, b) 0.1 to 0.6 parts by weight of dibenzylidene nonitol, and c) 0.005 to 0.01 parts by weight of amorphous silica. It provides a polypropylene resin composition.

This invention also provides the molded article manufactured from a polypropylene resin composition.

Hereinafter, the present invention will be described in more detail.

The present invention relates to an ultra-high transparency polypropylene resin composition and a molded article produced thereby, specifically, the resin composition of the present invention is a) ethylene-propylene random copolymer comprising ethylene in a predetermined content range, b) dibenzyl It is characterized in that it comprises a lidene nonitol-based nucleating agent, and c) amorphous silica in the optimum content range.

In particular, the present invention includes a dibenzylidene nonitol-based nucleating agent in a predetermined content range, which is much more transparent than the conventional polypropylene resin, and has a level of transparency or higher than that of polyethylene terephthalate (PET) resin and polycarbonate (PC). There is a feature in the invention of the random polypropylene resin having a significantly improved specific gravity.

Hereinafter, a polypropylene resin composition and a molded article manufactured therefrom according to a specific embodiment of the present invention will be described in detail. However, this is presented as an example of the invention, whereby the scope of the invention is not limited, it is apparent to those skilled in the art that various modifications to the embodiments are possible within the scope of the invention.

In addition, unless otherwise indicated throughout the specification, "including" or "containing" refers to the inclusion of any component (or component) without particular limitation and refers to the addition of another component (or component). It cannot be interpreted as excluding.

The polypropylene resin composition of the present invention is a random polypropylene resin comprising a) an ethylene-propylene random copolymer having an ethylene content of 3.5 to 8.0% by weight, preferably 3.8 to 7.5% by weight, more preferably 4.0 to 7.0% by weight. Can be used. In this case, the ethylene content of the ethylene-propylene random copolymer may be determined in consideration of deforming and unpleasant odor when securing the transparency of the polypropylene resin and molding. For example, when the ethylene content is used in an excessive amount, the low molecular weight extract increases, resulting in poor deforming during molding and an unpleasant odor.

In addition, the ethylene-propylene random copolymer has a melt index of 0.5 to 40 g / 10min, preferably 0.5 to 30 g / 10min, more preferably measured under a load condition of 230 ℃, 2.16 kg in accordance with ASTM evaluation method D1238 0.5 to 20 g / 10min. The melt index of the ethylene-propylene random copolymer may be 0.5 g / 10 min or more in terms of injection moldability, and 40 g / 10 min or less in terms of stretching after injection.

Accordingly, in the present invention, it is preferable to use an ethylene-propylene random copolymer having an ethylene content of 3.5 to 8.0 wt% and a melt index of 0.5 to 40 g / 10min measured under a load condition of 230 ° C. and 2.16 kg according to ASTM Evaluation Method D1238. desirable.

The polypropylene resin composition of the present invention contains b) dibenzylidene nonitol-based nucleating agent as a nucleating agent. Examples of the dibenzylidene nonitol-based nucleating agent is 1,2,3-tridioxy-4,6: 5,7-bis-O-[(4-propylphenyl) methylene] nonitol represented by the following Chemical Formula 1 Can be mentioned.

[Formula 1]

In order to increase the transparency of polypropylene, a nucleating agent of an organic phosphate ester metal salt system or a nucleating agent of a sorbitol system, which are commonly used as a nucleating agent, is limited in reducing crystal grain size, thereby limiting transparency. In addition, when an excessive amount of the conventional organic phosphate ester metal salt-based nucleating agent or sorbitol-based nucleating agent is added in an excessive amount, for example, based on 100 parts by weight of ethylene-propylene random copolymer, there is a problem that an unpleasant odor becomes worse. . On the other hand, the dibenzylidene nonitol-based nucleating agent used in the present invention can significantly reduce the crystal grain size of the polypropylene resin composition and ensure excellent transparency with a sufficient content because there is little unpleasant odor occurrence even in the case of excellent excessive prescription.

In particular, the conventionally known sorbitol-based nucleating agent has a characteristic that the transition to the surface is no longer absorbed by the polypropylene resin from a certain content (for example 2,000 ppm) or more, but used in the present invention, the dibenzylidene nonitol-based nucleating agent Due to its unique chemical structure, polypropylene resin can be absorbed in a large amount, and the crystal size is very small due to the addition of nucleating agent. At this time, the dibenzylidene nonitol-based nucleating agent has a fine fiber form in the polypropylene resin, and the fiber structure makes the lamellar crystal particles of the polypropylene smaller.

In addition, as described above, the sorbitol-based nucleating agent used in the past increases the amount of the sorbitol-based nucleating agent that is not absorbed by the polypropylene and shifts to the surface, causing an unpleasant odor, whereas the dibenzylidene nonitol-based nucleating agent of the present invention Since most of them are absorbed into the polypropylene resin, it is possible to secure ultra high transparency and minimize the occurrence of odor.

Dibenzylidene nonitol-based nucleating agent used to improve the transparency in the present invention is 0.1 to 0.6 parts by weight, preferably 0.15 to 0.55 parts by weight, more preferably 0.2 to 0.5 with respect to 100 parts by weight of the ethylene-propylene random copolymer It may be included so that parts by weight. The dibenzylidene nonnitol-based nucleating agent may be included in an amount of 0.1 parts by weight or more in terms of ensuring excellent transparency, and may be included in an amount of 0.6 parts by weight or less in terms of preventing an unpleasant odor and reducing cost burden.

The polypropylene resin composition of the present invention comprises a) ethylene-propylene random copolymer and b) dibenzylidene nonitol-based nucleating agent and c) amorphous silica (silicon dioxide). The amorphous silica is an additive used to solve nucleating agent agglomeration caused by excessive prescription of nucleating agent and to increase dispersibility, and has an effect of preventing blocking of a resin product as fine powder type silica.

The amorphous silica may have an average diameter of 0.5 μm or less or 0.1 μm to 0.5 μm, preferably 0.1 μm to 0.3 μm. In addition, the amorphous silica may have a BET specific surface area of at least 400 m ² / g or 400 to 700 m ² / g, preferably 500 to 700 m ² / g. In this case, the amorphous silica may have an average diameter of 0.5 μm or less and / or 400 m ² / g or more in terms of nucleating agent dispersibility.

The amorphous silica may be included in 0.005 to 0.01 parts by weight based on 100 parts by weight of ethylene-propylene random copolymer. The amorphous silica may be included as 0.005 parts by weight or more in terms of ensuring uniform transparency without deviation of transparency through excellent dispersion maintenance, and may be included in 0.01 parts by weight or less in terms of securing excellent transparency without deterioration of transparency.

In a preferred embodiment of the present invention, the polypropylene resin composition is a) based on 100 parts by weight of ethylene-propylene random copolymer having an ethylene content of 3.5 to 8.0% by weight, b) dibenzylidene nonitol based nucleating agent is the ethylene- 0.1 to 0.6 parts by weight, preferably 0.15 to 0.55 parts by weight, more preferably 0.2 to 0.5 parts by weight and c) amorphous silica content, based on 100 parts by weight of propylene random copolymer, may comprise 0.005 to 0.01 parts by weight. .

In addition, the polypropylene resin composition may further include additives such as neutralizing agents, antistatic agents, antioxidant neutralizing agents, etc. in addition to the ethylene-propylene random copolymer, dibenzylidene nonitol, and amorphous silica. .

The polypropylene resin composition according to the present invention may have an average particle size of 150 μm or less, preferably 130 μm or less, more preferably 100 μm or less, as measured by an optical microscope.

The present invention also provides a molded article produced from the polypropylene resin composition. In particular, the molded article may be a plastic molded article, such as injection, stretch blow molding and direct blow molded article with the polypropylene resin composition of the present invention, the molded article may be a film, a container or the like.

The molded article produced according to the present invention may preferably have a haze measured according to ASTM Evaluation Method D1003 of 10% or less.

Since the specific gravity of the molded article is about 30% or less than that of the PET and PC transparent container resins used in the conventional blow blow molding, it is possible to reduce the weight and contribute to the reduction of petrochemical resources.

In addition, the molded article may be divided into 1 to 5 grades as a sensory evaluation, and the sample having the least odor may be rated as 5 grades, and the sample with the most odor may be classified into 1 grade. At this time, the odor grade of the molded article may be preferably at least 3.5 grade, more preferably at least 4 grade. Generally, if it is 4 grades or more, it is known that it can be used very well in the industry, such as manufacturing a transparent container.

The manufacturing method of the molded article which concerns on this invention is not specifically limited, It can manufacture by applying all the methods known in this field.

The final form of the molded article according to the embodiment of the present invention is a) 100 parts by weight of polypropylene resin having an ethylene content of 3.5 to 8.0% by weight, 0.1 to 0.6 parts by weight of dibenzylidene nonitol-based nucleating agent and 0.005 to 0.01 amorphous silica It may be provided in a form containing parts by weight.

Molded article according to the embodiment of the present invention is not limited to the field used, but may be preferably used as a transparent food container. Specifically, it may be used as a transparent side dish container, a baby bottle container.

In the present invention, matters other than those described above can be added or subtracted as necessary, and therefore the present invention is not particularly limited.

The polypropylene resin composition of the present invention includes dibenzylidene nonitol-based nucleating agent and amorphous silica in an optimal range in an ethylene-propylene random copolymer having a predetermined ethylene content range, thereby providing excellent transparency than conventional polypropylene resins. It is possible to secure ultra-high transparency that is equivalent to that of amorphous resins such as PET and PC, and at the same time, it has an excellent effect of significantly reducing the occurrence of odor and securing improved productivity.

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

Example  1 to 3

Dibenzylidene was used as the composition and content as shown in Table 1 below, using a random polypropylene resin (manufacturer: Honam Petrochemical) having a melt index of 8 g / 10 min and an ethylene content of 4.5 wt% as an ethylene-propylene random copolymer. 1,2,3-tridioxy-4,6: 5,7-bis-O-[(4-propylphenyl) methylene] nonitol is used as a nonitol-based nucleating agent, and the dispersant is an amorphous having an average diameter of 0.5 μm. A polypropylene resin composition containing silica was prepared.

Comparative example  1 to 2

To the composition and content as shown in Table 1 below, a random polypropylene resin (manufacturer: Honam Petrochemical) and a melt index of 8 g / 10 min, an ethylene content of 3.0 wt%, respectively, as an ethylene-propylene random copolymer, and a melt index of 8 g / A polypropylene resin composition was prepared in the same manner as in Example 1, except that 10 min, a random polypropylene resin (manufacturer: Honam Petrochemical) having an ethylene content of 8.5 wt% was used.

Comparative example  3 to 5

A polypropylene resin composition was prepared in the same manner as in Example 1, except that the content and content of the dibenzylidene noniitol-based nucleating agent and amorphous silica were used differently as shown in Table 1 below.

Comparative example  6 to 8

In the same manner as in Example 1, except that a sorbitol-based nucleating agent, an organophosphate-based nucleating agent, and an inorganic nucleating agent (talc) were used in place of the dibenzylidene nonitol-based nucleating agent in the composition and content as shown in Table 1 below. A resin composition was prepared.

Comparative example  9

A polypropylene resin composition was prepared in the same manner as in Example 1, except that silica was not used as a dispersant in the composition and content as shown in Table 1 below.

division Ethylene-propylene Random Copolymer Nucleating agent Dispersant Ethylene
content
(wt%) Melt index
(g / 10 min)
content
(Parts by weight) ingredient content
(Parts by weight) ingredient content
(Parts by weight) Example 1 4.5 8 100 Dibenzylidene
Nonitol 0.4 Silica 0.0075 Example 2 4.5 8 100 Dibenzylidene
Nonitol 0.2 Silica 0.005 Example 3 4.5 8 100 Dibenzylidene
Nonitol 0.6 Silica 0.01 Comparative Example 1 3.0 8 100 Dibenzylidene
Nonitol 0.4 Silica 0.0075 Comparative Example 2 8.5 8 100 Dibenzylidene
Nonitol 0.4 Silica 0.0075 Comparative Example 3 4.5 8 100 Dibenzylidene
Nonitol 0.05 Silica 0.005 Comparative Example 4 4.5 8 100 Dibenzylidene
Nonitol 0.65 Silica 0.01 Comparative Example 5 4.5 8 100 Dibenzylidene
Nonitol 0.4 Silica 0.015 Comparative Example 6 4.5 8 100 Sorbitol 0.4 Silica 0.0075 Comparative Example 7 4.5 8 100 Organophosphorus 0.4 Silica 0.0075 Comparative Example 8 4.5 8 100 Talc 0.4 Silica 0.0075 Comparative Example 9 4.5 8 100 Nobitol 0.4 - -

Experimental Example

After the injection molding process in the polypropylene resin composition according to Examples 1 to 3 and Comparative Examples 1 to 9 in the 210 to 250 ℃ range to prepare a plastic molded article, to prepare an injection specimen sheet having a thickness of 2 mm The physical properties of each were measured by the following method.

transparency

The transparency of the plastic molded article specimen sheet was evaluated by a haze value, and the haze value was measured according to the ASTM D1003 evaluation method.

Odor Evaluation

As a sensory evaluation, ten evaluation experts participated and divided into 1 to 5 grades, and the samples with the least odor were classified into 5 grades, and the samples with the most odor were classified into 1 grade.

Physical properties measured for the polypropylene (PP) resin composition obtained according to Examples 1 to 3 and Comparative Examples 1 to 9 and the plastic molded article prepared therefrom are shown in Table 2 below.

division PP Resin Composition Average Crystal Grain Size
(Μm) transparency
(Haze,%) smell
(Rating) Demold time
(sec) Example 1 110 8 4.5 15 Example 2 125 10 5 17 Example 3 85 5 4 15 Comparative Example 1 170 18 4.5 13 Comparative Example 2 120 7 2 28 Comparative Example 3 190 20 5 21 Comparative Example 4 70 5 2.5 14 Comparative Example 5 115 16 4 15 Comparative Example 6 205 28 3 17 Comparative Example 7 220 30 3 17 Comparative Example 8 280 45 2 18 Comparative Example 9 180 15 4.5 16

As shown in Table 2, according to the present invention Examples 1 to 1 containing an ethylene-propylene random copolymer containing ethylene, a dibenzylidene notitol-based nucleating agent, and amorphous silica in an optimum content range according to the present invention. The polypropylene resin composition of 3 had an extremely small average crystal grain size of 125 µm or less, and all the plastic moldings produced therefrom had very high haze of 5% to 10%, and at the same time, the odor evaluation grade was also 4 or more. It can be seen that it shows very excellent physical properties.

On the other hand, the plastic molded article prepared from Comparative Examples 1, 3, 5, and 9 was able to obtain an improvement effect similar to Examples 1 to 3 in the odor grading, but the haze value is 15% to 20% transparency It can be seen that it can not be used as a transparent container or the like remarkably. In addition, the plastic molded articles prepared from Comparative Examples 2 and 4 exhibited average crystal grain size and haze value to a degree similar to those of Examples 1 to 3, and improved transparency could be obtained, but the odor evaluation grade was markedly from 2 to 2.5 grade. It can be seen that there is a problem when using the product due to the unpleasant smell. In particular, it can be seen that the plastic molded article prepared from Comparative Examples 6 to 8 had a haze value of 18% to 45%, and not only a drop in transparency, but also a very poor odor evaluation grade of 2 to 3 grade.

Furthermore, it can be seen that the polypropylene resin compositions of Comparative Examples 1, 3, and 6 to 9 significantly increased the average crystal grain size to 170 μm to 280 μm, so that the transparency of the plastic molded article prepared therefrom was not good. Particularly, in Comparative Example 9, since the nucleating agent is not dispersed well due to the absence of silica, variation in haze value is severe for each part, and the nucleating agent is dispersed in the nucleating agent, but most of the crystal grain size is small enough to be 100 μm or less, but the nucleating agent is dispersed. In the non-particulates, most of the crystal grain sizes exceeded 300 μm and the average value reached 180 μm, and the transparency of the plastic molded product manufactured therefrom also showed a severe variation in the corresponding parts.

In addition, in the case of Comparative Examples 2 and 3, the demolding time reached about 21 seconds and 28 seconds, and it was found that the mold demolding was considerably lowered and that the process was nearly defective.

Thus, according to Examples 1 to 3 according to the present invention can ensure excellent transparency with a haze value of 10% or less at the same level as polyethylene terephthalate (PET) resin and polycarbonate (PC), both specific gravity 0.9 degree Compared with the polyethylene terephthalate (PET) resin and polycarbonate (PC) of about 1.3 to 1.4, it is possible to reduce the petrochemical resources by reducing the weight due to improved physical properties.

Claims (8)

a) 100 parts by weight of ethylene-propylene random copolymer having an ethylene content of 3.5 to 8.0% by weight, b) 0.1 to 0.6 parts by weight of the dibenzylidene nonitol compound, and c) 0.005 to 0.01 parts by weight of amorphous silica Polypropylene resin composition comprising a. The method of claim 1, The polypropylene resin composition whose average particle size of the said polypropylene resin composition is 150 micrometers or less. The method of claim 1, The a) ethylene-propylene random copolymer is a polypropylene resin composition having a melt index of 0.5 to 40 g / 10min measured under 2.16 kg load conditions at 230 ℃ according to ASTM evaluation method D1238. The method of claim 1, B) a polypropylene resin composition wherein the dibenzylidene nonitol compound nucleating agent is 1,2,3-tridioxy-4,6: 5,7-bis-O-[(4-propylphenyl) methylene] nonitol The method of claim 1, The polypropylene resin composition of c) amorphous silica has an average diameter of 0.5 μm or less. The method of claim 1, The c) amorphous silica is a polypropylene resin composition having a BET specific surface area of 400 m ² / g or more. The molded article manufactured from the polypropylene resin composition of any one of Claims 1-6. The method of claim 7, wherein A molded article having a haze of 10% or less by ASTM evaluation method D1003 of the molded article.