JPH0588264B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a hollow bottle molded from a polypropylene composition and having excellent low-temperature impact resistance. Prior art and technical problems to be solved Polypropylene has good rigidity and transparency, and has excellent chemical resistance and hygienic properties.
It is attracting attention for its use as a hollow bottle. However, since low-temperature drop impact strength, which is a drawback of polypropylene, is required for hollow bottle applications, it is essential to improve low-temperature impact resistance. Research has been carried out to improve low-temperature impact resistance by blending polypropylene with other polyolefins, but since rigidity, transparency and low-temperature impact resistance have an antinomic relationship, it has been difficult to balance this. The current situation is that OBJECT AND SUMMARY OF THE INVENTION An object of the present invention is to provide a hollow bottle that has excellent rigidity, transparency, and low-temperature impact resistance. According to the present invention, the density is 0.90 to 0.91/cm ³ ,
70 to 85 parts by weight of polypropylene resin with MFR of 0.1 to 3.0 g/10 min (190°C, 2160 g), 5 to 20 parts of linear low density polyethylene with density of 0.915 to 0.935 g/cm ³ and MFR of 0.1 to 10 g/10 min. and density 0.87
Low-temperature molding made from a polypropylene composition blended with 2 to 20 parts by weight of a soft elastomer made of a copolymer of ethylene and an olefin having 3 or more carbon atoms, with a MFR of 0.89 g/cm ³ and MFR of 0.1 to 40 g/10 min. A neutral bottle with excellent impact resistance is provided. Structure of the Invention The polypropylene resin used in the present invention includes not only polypropylene homopolymer but also
Random copolymers of broprene and other olefins may be used within a range that does not impair the properties of polypropylene, such as transparency and rigidity. In addition, this polypropylene resin has a density of
0.90 to 0.91 g/cm ³ is preferably used, and from the viewpoint of moldability etc.
MFR) is 0.1 to 3.0g/10min (ASTM
-D-1238, the value measured at 190°C under a load of 2160g (the same applies hereinafter) is suitable. The linear low-density polyethylene used in the present invention has several characteristics that are not found in commonly used high-pressure low-density polyethylene and low-pressure high-density polyethylene. In other words, high-pressure low-density polyethylene has a long-chain branched molecular structure and is a single polymer of ethylene, whereas linear low-density polyethylene has a substantially linear molecular structure and is a monopolymer of ethylene. It consists of a copolymer with an α-olefin having 4 to 8 carbon atoms. On the other hand, low-pressure high-density polyethylene has a density (25
°C) is in the range of 0.940 to 0.965 g/ ^cm3 , and its molecular structure has almost no short branched chains, whereas linear low-density polyethylene has a density of
It is in the range of 0.915 to 0.935g/ ^cm3 , and the α
- They differ in that they have short branched chains derived from olefins. Comonomers in this linear low-density polyethylene include those having a carbon number of 4 to 1, such as butene-1, pentene-1, 4-methylpentene-1, hexene-1,2-methyl-butene-1, and octene-1. α of 8
-Olefins can be mentioned, and these α-
The olefins are incorporated into the polymer chain in a total amount of 1 to 20% by weight, in particular 3 to 15% by weight. This linear low density polyethylene (L-LDPE)
Also related to the chemical structure mentioned above, other olefin resins, such as high-pressure low density polyethylene (HP
-LDPE), high-density polyethylene (HDPE), crystalline propylene ethylene copolymer (PPE), etc., it has similar physical properties as shown in Table A below.

[Table] From Table A above, it is clear that the linear low density polyethylene blended with the polypropylene resin has the characteristics of having a low melting point while having high elongation and strength. In the present invention, among these linear low density polyethylenes, those having an MFR of 0.1 to 10 g/10 min are preferably used. Furthermore, the soft elastomer used in the present invention is a copolymer elastomer of ethylene and an olefin having 3 or more carbon atoms, that is, a copolymer elastomer of ethylene and an olefin such as propylene, butene, hexene, octene, or decene. , density is 0.87 to 0.89g/cm ³ , and MFR is
Those in the range of 0.1 to 40g/10min are used. In the present invention, the above polypropylene resin 70
A polypropylene composition is prepared by blending 85 to 85 parts by weight, especially 75 to 85 parts by weight, 5 to 25 parts by weight, especially 15 to 20 parts by weight of LLDPE, and 2 to 20 parts by weight, especially 5 to 10 parts by weight of a soft elastomer. The polypropylene composition of the present invention has excellent rigidity and transparency, and as shown in the examples below, has significantly improved impact resistance at low temperatures, and is particularly applicable to hollow bottles. If the amount of polypropylene resin used is more than the above range, the impact resistance at low temperatures will be unsatisfactory, and if it is less, the rigidity, transparency, etc. peculiar to polypropylene will be unsatisfactory. Therefore, similar disadvantages will occur if the amount of LLDPE and soft elastomer is less than or greater than the above range. That is, by blending the polypropylene resin, LLDPE, and soft elastomer according to the above-mentioned compounding ratio, a polypropylene composition having an excellent combination of rigidity, transparency, and low-temperature impact resistance can be obtained. In the present invention, various methods can be used to blend these components, such as mechanically mixing the solid components, blending them in a melt state, blending them in a solution state, etc. The most suitable method is There is no particular restriction on the method for producing a hollow molded body using the composition as described above, and various known methods can be employed. That is, the method for producing a hollow molded body using the composition of the present invention as described above basically involves forming a precursor (for example, a parison) using a molding method such as an extrusion method or an injection method using the composition. ), this precursor (parison) is sandwiched between molds, and pressurized air is blown into the interior to expand the precursor until it comes into close contact with the blow mold, thereby shaping it into the desired shape. Examples of methods for producing such hollow molded bodies include extrusion blow molding, injection blow molding, cold parison method, and sheet material blow molding. The invention is illustrated by the following example. Example 1 Polypropylene homopolymer as polypropylene resin (MFR 0.5 g/10 min, density 0.91 g/cm ³ )
using L-LDPE (MFR2.0g/10min, density
0.920g/cm ³ ) and ethylene-propylene copolymer soft elastomer (MFR 0.4g/10min, density
0.880g/cm ³ ) according to the formulations in Table 1 below to prepare polypropylene compositions (Samples 1 to 3).
5) was prepared.

[Table] *Samples 1 and 2 are examples of the present invention, samples 3~
5 is a comparative example. Using this composition, a cylindrical bottle (400 c.c., 20 g, thickness 0.7
mm), a sheet (thickness 2 to 3 mm) was molded and various physical properties were measured. The results are shown in Table 2. Example 2 A random copolymer of polypropylene (MFR 0.5 g/10 min, density 0.91
Samples 1 to 3 of Example 1 except that g/cm ³ ) was used.
Polypropylene compositions were prepared using the same formulation as above (Samples 6, 7, and 8), and hollow bottles and sheets were obtained in the same manner. These various physical properties are also shown in Table 2. Example 3 A polypropylene block copolymer (MFR 0.5 g/10 min, density 0.91
A polypropylene composition (Sample 9) was prepared in the same manner as Sample 1 of Example 1, except that 100 g/cm ³ ) was used, and a hollow bottle and a sheet were obtained in the same manner. The physical properties are shown in Table 2. Example 4 For comparison, polypropylene homopolymer (MFR 0.5 g/10 min, density 0.91 g/cm ³ ), random copolymer (MFR 0.5 g/10 min, density 0.91 g/cm 3 )
cm ³ ), and block copolymer (MFR0.5g/
10 min, density 0.91 g/cm ³ ) were used alone to obtain hollow bottles and sheets (Samples 10, 11, 12).
Table 2 shows these various physical properties.

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【table】

Claims (1)

[Claims] 1. Density 0.90 to 0.91/cm ³ , MFR 0.1 to 3.0 g/
10min (190℃, 2160g) polypropylene resin 70
85 parts by weight, density 0.915 to 0.935 g/cm ³ ,
5 to 20 parts by weight of linear low density polyethylene with MFR of 0.1 to 10 g/10 min and density of 0.87 to 0.89 g/
cm ³ , MFR 0.1 to 40 g/10 min of ethylene and 2 to 20 parts by weight of a soft elastomer made of a copolymer of olefin having 3 or more carbon atoms. Excellent neutral bottle. 2. The hollow bottle according to claim 1, wherein the polypropylene resin is a polypropylene homopolymer or a random copolymer of propylene and another olefin.