KR100601147B1 - Polypropylene composition for films with excellent water barrier property - Google Patents

Abstract

The present invention relates to a polypropylene resin composition for films having excellent moisture barrier properties, and more particularly, to 100 parts by weight of polypropylene having an isotactic pentad index of 95% or more and a molecular weight distribution of 8.0 or less. It relates to a polypropylene resin composition for films having a composition by weight. Such a polypropylene resin composition for films of the present invention is excellent in moisture barrier property, process stability and heat shrinkability.

Description

Polypropylene composition for films with excellent water barrier property

The present invention relates to a polypropylene resin composition used for producing a biaxially stretched polypropylene film for aluminum deposition having excellent moisture barrier properties.

Metal-deposited plastic films in which metals are deposited under vacuum have excellent moisture barrier properties, gas barrier properties, light barrier properties, appearance, and the like, and are widely used for packaging various products. Of these, biaxially stretched polypropylene films, particularly for aluminum deposition, are most frequently used because of their excellent strength, heat resistance, and low cost.

Biaxially stretched polypropylene films for aluminum deposition are relatively superior to other plastic films in terms of moisture barrier properties but cannot be used in applications requiring high moisture barrier. Conventionally, various methods have been used to solve this problem. For example, in order to exhibit high moisture barrier properties, a multilayer film is applied, and high moisture barrier polyvinylidene chloride (PVDC) is coated (US Pat. No. 4,364,989), or a high crystalline resin having a stereoregularity of 93% or more. A polyterpene (POLYTERPENE) was properly mixed to prepare a film (US Pat. No. 5,500,282). However, in the case of coating other functional resins as described above, the process is complicated and accompanied by an increase in costs, and in the case of mixing polyterpenes with high crystalline resins, problems of odor and blocking peculiar to polyterpenes occur. It was limited.

In general, in order to obtain appropriate processing stability in a polypropylene resin composition, a phenolic compound, a tris (2,4-di-tert-butyl-phenyl) phosphite, a bis (2,4-di-ter), etc. Phosphorus compounds such as sherry-butyl-phenyl-1,2-di-hydroquinoline) are mostly used at the same time, but when phosphorus compounds are used, the hydrophilicity of the resin increases due to the decomposition of the phosphorus compounds generated during processing. This has the disadvantage of declining.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above to provide a polypropylene resin composition for films excellent in moisture barrier property and processing stability and also excellent in heat shrinkability.

The polypropylene resin composition of this invention is manufactured by mixing 0.2-0.8 weight part of phenolic antioxidants with 100 weight part of polypropylene resins whose isotactic pentad index is 95% or more and molecular weight distribution is 8.0 or less.

As the propylene homopolymer, the polypropylene resin used in the present invention is more preferably an isotactic pentad index of 95% or more, a molecular weight distribution of 8.0 or less, and a molecular weight distribution of 5.0 to 8.0. When the polypropylene resin having an isotactic pentad index of less than 95% is used, the crystallinity of the film is low, so that the desired moisture barrier property is not obtained, and when the molecular weight distribution exceeds 8.0, the desired shrinkage rate is not obtained.

The phenolic antioxidant used in the present invention is 3,5-di-tert-butyl-4-hydroxytoluene, pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-butyl- 4-hydroxyphenyl)] propionate, octadecyl (3,5-di-tert-butyl-4-hydroxy) propionate, tetrakis [methylene-3- (3,5-di-tertary) 0.2 to 0.8 parts by weight of -butyl-4-hydroxyphenyl) propionate] methane and the like, and two or more compounds may be used simultaneously. It is not preferable because it is inferior to the moisture barrier property and processability outside the content range.

In the polypropylene resin composition used in the present invention, in addition to the antioxidants described above, chlorine inerts, anti-blocking agents and the like can be used together as usual additives as necessary.

There is no restriction | limiting in particular in the method of manufacturing the resin composition of this invention, The method of manufacturing the polypropylene resin composition generally known can be used. The polypropylene resin and each additive component can be freely selected and mixed in the desired order. In general, a method of kneading using a kneader such as a kneader, a roll, a short-barrier mixer, a single-screw or twin-screw extruder, or the like by adding a polypropylene resin and respective components in a required amount may be used.

The resin composition of this invention is used as a material of the biaxially stretched polypropylene film for aluminum vapor deposition.

The plastic film produced using the resin composition of the present invention can be molded by conventional T-die method and sequential stretching method. Moreover, as a form of a plastic film, it is also possible to apply in the form of the multilayer film using the resin composition of this invention in both outermost layers or one outermost layer besides a single plastic film. When the resin composition of this invention is applied to one outermost layer, metal deposition is performed on the surface. On the surface where the deposition is performed, the wettability is improved by performing a surface treatment such as corona discharge treatment or flame treatment during film production. Deposition is carried out by a conventional vacuum deposition method, and the thickness of the deposited film usually reaches 50 to 500 kPa.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the examples.

Measurement of the overall physical properties in each Example and Comparative Example is as follows.

Isotactic pentad index: Measured using a nuclear magnetic resonance spectrometer.

○ Molecular weight distribution: Calculated by the ratio of weight average molecular weight and number average molecular weight using GPC (Gel Permeation Chromatography).

○ Workability: In order to evaluate the process stability of the resin, the change of the melt index (MI) was measured by repeated extrusion three times using a single screw extruder. At this time, the processing temperature is 250 ℃.

Manufacture of Biaxially Stretched Film: A biaxially oriented film was manufactured using a Burgner biaxially oriented film manufacturing equipment, followed by vacuum deposition using aluminum. The processing temperature for film production is extruder and die 260 ° C, longitudinal direction (MD: film processing machine direction) stretching temperature 140 ° C, direction perpendicular to MD direction (TD) stretching temperature 165 ° C. The thickness of the film is 20μ.

○ Moisture barrier property: Moisture permeability of the biaxially oriented film for deposition was measured at a measurement temperature of 38 ℃ using Mocon equipment. The lower the moisture permeability, the better the moisture barrier property.

○ Heat shrinkage rate: The stretched film was cut into 100mm × 10mm, and the prepared sample was put in a hot air oven at 150 ° C. and left for 5 minutes, and then the length was measured.

Each example contains 0.02 parts by weight of calcium stearate and 0.02 parts by weight of hydrotalcite as a chlorine inactivator.

Example 1 and Comparative Example 1

Example 1 is a polypropylene resin having an isotactic pentad index of 96% and a molecular weight distribution of 5 as pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydrogen) as an antioxidant. Oxyphenyl)] propionate was prepared by mixing 0.1 part by weight of 0.1 part by weight of 3,5-di-tert-butyl-4-hydroxytoluene. Comparative Example 1 was prepared from a polypropylene resin composition having the same items as in Example 1 but having an isotactic pentad index of 90. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

Example 2

Example 2 0.1 parts by weight of octadecyl (3,5-di-tert-butyl-4-hydroxy) propionate as an antioxidant in a polypropylene resin having an isotactic pentad index of 96% and a molecular weight distribution of 5 And 0.15 parts by weight of 3,5-di-tert-butyl-4-hydroxytoluene was prepared. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

Example 3

Example 3 is a polypropylene resin having an isotactic pentad index of 96% and a molecular weight distribution of 5 as pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydrogen) as an antioxidant. Oxyphenyl)] propionate was prepared by mixing 0.4 parts by weight. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

Comparative Example 2

Other items are the same as in Example 3, but were prepared by mixing 0.1 part by weight of pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl)] propionate as an antioxidant. It became. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

Comparative Example 3

The other items are the same as in Example 1, but 0.1 part by weight of pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl)] propionate and tris ( It was prepared by mixing 0.1 parts by weight of 2,4-di-tert-butyl-phenyl) phosphite. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

Comparative Example 4

Other items were prepared in the same manner as in Example 1 but using a polypropylene resin having a molecular weight distribution of 10. The physical property measurement results of the biaxially oriented film for deposition made of the polypropylene resin composition prepared as described above are shown in Table 1 below.

As shown in the results of Table 1, the film made of the resin composition of the present invention showed excellent moisture barrier property, process stability, and heat shrinkability as compared with the comparative example.

Claims (2)

A polypropylene resin composition comprising an isotactic pentad index of 95% or more and comprising 100 parts by weight of a polypropylene resin having a molecular weight distribution of 5.0 to 8.0 and 0.2 to 0.8 parts by weight of a phenolic antioxidant. The phenolic antioxidant according to claim 1, wherein the phenolic antioxidant is 3,5-di-tert-butyl-4-hydroxytoluene, pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-butyl-) 4-hydroxyphenyl)] propionate, octadecyl (3,5-di-tert-butyl-4-hydroxy) propionate, tetrakis [methylene-3- (3,5-di-tertary) -Butyl-4-hydroxyphenyl) propionate] methane. The polypropylene resin composition characterized by the above-mentioned.