JP2733479B2 - Polypropylene resin composition - Google Patents

Description

The present invention relates to a polypropylene resin composition having excellent heat seal strength, low-temperature impact resistance and transparency when used as a film, for example.

[Conventional technology]

Polypropylene resin is excellent in rigidity, heat resistance, etc., but has the disadvantage of low impact strength, especially low-temperature impact resistance. It is well known that a rubber component composed of an ethylene random copolymer such as an ethylene / propylene random copolymer or an ethylene / butene random copolymer is mixed with a polypropylene resin for the purpose of remedying this drawback.

However, in such a conventional polypropylene resin composition, since the dispersed particle diameter of a rubber component such as an ethylene / propylene random copolymer or an ethylene / butene random copolymer in the resin composition is large, the heat sealing strength is low. Therefore, it is generally difficult to obtain a composition having a good balance between heat seal strength and low-temperature impact resistance, and there are problems such as poor transparency.

[Problems to be solved by the invention]

An object of the present invention is to solve the above problems by reducing the dispersed particle diameter of the rubber component in the resin composition, improving the heat sealing strength, and having excellent low-temperature impact resistance and transparency. To provide a polypropylene resin composition.

[Means for solving the problem]

The present invention comprises: (A) 50 to 99% by weight of a polypropylene resin, and (B) 1 to 50% by weight of a rubber component, wherein the rubber component (B) comprises: (i) an ethylene content of 60 to 95 mol%, _{230 ℃} 0.1〜5
An ethylene random copolymer selected from a random copolymer of 0 g / 10 min of ethylene and an α-olefin having 3 to 20 carbon atoms; (ii) 1-butene content of 60 to 99 mol%, MFR _{230 ° C} 0.1
1 to 50 g / 10 min 1-butene and 2 carbon atoms excluding 1-butene
And a 1-butene random copolymer selected from random copolymers with α-olefins having a weight ratio of 95: 5 to
A polypropylene resin composition comprising a random copolymer composition in a range of 5:95.

The polypropylene resin (A) used in the present invention may be a homopolymer of propylene or a random or block copolymer of propylene and another α-olefin such as ethylene and 1-butene (usually propylene units). (A content of 90 mol% or more) and having a boiling n-heptane insoluble content of 90% or more, preferably 93% or more.

Such a polypropylene resin (A) can be typically produced using a catalyst formed from a solid titanium catalyst component and an organometallic compound component, or a catalyst formed from both components and an electron donor. . As the solid titanium catalyst component, titanium trichloride or a titanium trichloride composition produced by various methods, or magnesium, a halogen, an electron donor, preferably an aromatic carboxylic acid ester or an alkyl group-containing ether and titanium are essential components. It is a titanium catalyst component with a carrier having a specific surface area of preferably 100 m ² / g or more. In particular, those produced using the latter catalyst component with a carrier are preferred. As the organometallic compound, an organoaluminum compound is preferable, for example, trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, etc., and the preferable one varies depending on the type of the titanium catalyst component. The electron donor is an organic compound containing nitrogen, phosphorus, sulfur, oxygen, silicon, boron and the like, and preferable examples thereof include esters and ethers.

Regarding the method for producing polypropylene using the supported catalyst component, for example, JP-A-50-108385, JP-A-50-126590,
It is disclosed in JP-A-51-20297, JP-A-51-28189, JP-A-52-151691, and the like.

The ethylene-based random copolymer (i) constituting the rubber component (B) is a random copolymer rubber of ethylene and an α-olefin having 3 to 20 carbon atoms, which is mainly composed of ethylene. is there. As the ethylene random copolymer (i), an ethylene content of 60 to 95 mol%, preferably 70 to 93 mol%, more preferably 75 to 91 mol%, MF
R _{230 ℃} (Melt index: ASTM D 1238,65T, 230 ℃,
The same applies hereinafter. ) 0.1-50g / 10min, preferably 0.1-2
0g / 10min, crystallinity 40% or less, preferably 20% or less, α
-An ethylene / α-olefin random copolymer having 3 to 20, preferably 3 to 10, and more preferably 3 to 6 carbon atoms of the olefin can be used. These ethylene-based random copolymers (i) can be used alone or in combination of two or more.

If the ethylene content is less than 60 mol%, the handleability of the resin becomes poor due to blocking or the like. On the other hand, if it exceeds 95 mol%, the effect of improving low-temperature impact resistance is lost. MF
When R _{230 ° C} is out of the above range, dispersibility in polypropylene becomes poor. When the crystallinity exceeds 40%, the effect as an impact modifier is lost. When the number of carbon atoms exceeds 20, the rubbery properties of the polymer become small, and the effect as an impact modifier is lost.

The 1-butene random copolymer (ii) constituting the rubber component (B) is a random copolymer rubber of 1-butene and an α-olefin having 2 to 20 carbon atoms excluding 1-butene. And 1-butene as a main component. The 1-butene random copolymer (ii) has a 1-butene content of 60 to 99 mol%, preferably 70 to 99 mol%, and an MFR of _{230 ° C.}
1 to 50 g / 10 min, preferably 0.1 to 20 g / 10 min, 2 to 20 carbon atoms of the α-olefin except 1-butene, preferably 2 to 2
10, and more preferably 2 to 6 1-butene-α-olefin random copolymers can be used. These 1-butene random copolymers (ii) can be used alone or as a mixture of two or more.

The ethylene random copolymer (i) can be produced by randomly polymerizing a plurality of monomers using a catalyst system comprising a soluble vanadium compound and an alkylaluminum halide compound.

Examples of the soluble vanadium compound used as a polymerization catalyst include vanadium tetrachloride, vanadium oxytrichloride, vanadium triacetylacetonate, and oxyvanadium triacetylacetonate. Examples of the alkylaluminum halide compound constituting the polymerization catalyst in combination with the soluble vanadium compound include, for example, ethylaluminum dichloride, diethylaluminum monochloride, ethylaluminum sesquichloride, diethylaluminum monobromide, diisobutylaluminum monochloride, isobutylaluminum dichloride, isobutyl Aluminum sesquichloride and the like can be mentioned.

The polymerization can be carried out in the form of a solution or a suspension or in an intermediate region thereof, and in any case, it is preferable to use an inert solvent as a reaction medium. Examples of the solvent used for the polymerization include aliphatic hydrocarbons having about 3 to 12 carbon atoms, such as propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, kerosene and halogenated hydrocarbons. For example, methyl chloride, ethyl chloride, ethylene dichloride and the like can be used alone or as a mixture. The polymerization temperature is usually 0
~ 100 ° C.

The 1-butene random copolymer (ii) can be produced by randomly polymerizing a plurality of monomers by the same operation using the same catalyst as in the case of the polypropylene resin (A).

The rubber component (B) of the present invention has a weight ratio of the ethylene-based random copolymer (i): 1-butene-based random copolymer (ii) of 95: 5 to 5:95, preferably 70:30 to 5:95. It is composed of a random copolymer composition blended at a ratio of 30:70.

The polypropylene resin composition of the present invention comprises 50 to 99% by weight, preferably 70 to 90% by weight of the polypropylene resin (A) and 1 to 50% by weight, preferably 10 to 50% by weight of the rubber component (B).
~ 30% by weight.

The polypropylene resin composition of the present invention may contain other resin components such as a polyethylene resin as long as the object of the present invention is not impaired, and may include an antioxidant, an ultraviolet absorber, a lubricant, a nucleating agent, and an antistatic agent. Various additives such as an agent, a flame retardant, a pigment, a dye, and an inorganic or organic filler can be blended.

To prepare the polypropylene resin composition of the present invention,
Any known method can be adopted, for example, a V-type blender,
A method of mixing with a mixer such as a ribbon blender or a Henschel mixer and / or a method of kneading with a kneader such as an extruder, a mixing roll, a Banbury mixer, or a kneader can be used alone or in combination. There is no particular limitation on the order in which the components are mixed,
A method in which the ethylene-based random copolymer (i) and the 1-butene-based random copolymer (ii) are mixed first and then the polypropylene resin (A) is mixed, or a method in which the three components are mixed at once. Can be adopted.

The polypropylene resin composition obtained in this manner has a 1-butene random copolymer as a rubber component, so that the dispersibility of the ethylene random copolymer in the polypropylene resin is good, and thus the dispersed particle diameter is small. Thus, a molded product such as a film having improved heat seal strength and excellent low-temperature impact resistance and transparency can be obtained.

The polypropylene resin composition of the present invention is suitable for films, sheets and the like that require heat sealability, low-temperature impact resistance and transparency, such as packaging films, but can be used as other molded products.

〔The invention's effect〕

As described above, the polypropylene resin composition of the present invention,
Since it contains a rubber component composed of an ethylene-based random copolymer and a 1-butene-based random copolymer, heat sealability can be improved, and low-temperature impact resistance and transparency are excellent.

〔Example〕

Hereinafter, examples of the present invention will be described. In each example, parts represent parts by weight, and% represents mol%.

Example 1 Ethylene content 3.5%, MFR _{230 ° C} 6.5g / 10min, melting point (T
m) 85 parts of polypropylene resin at 141 ° C, ethylene content 81
%, MFR _{230 ° C} 5 parts ethylene-propylene random copolymer 5.4g / 10min, 1-butene content 88%, MFR
Ten parts of 1-butene / ethylene random copolymer having a Tm of 100 ° C. and a temperature of _{230 ° C. of} 5.4 g / 10 min were mixed with a Henschel mixer, pelletized, and then formed into a film to form a film having a thickness of 60 μm.

Next, the film impact, haze (haze), gloss (gloss), and heat sealing characteristics at 0 ° C. of the obtained film were measured. Here, the film impact was measured using a pendulum type film impact measuring device. In addition, the film has a heat sealing property of 2 kg / cm
Heat seal start temperature (HS start temperature) and heat seal strength at 150 ° C (HS strength) when heat seal at 300mm / min and T peel at 300mm / min for 1 second under pressure of ² Was measured. Table 1 shows the results.

Examples 2 to 12 and Comparative Examples 1 to 5 Films were formed in the same manner as in Example 1 according to the compositions shown in Table 1, and measurements were made. Table 1 shows the results.

Claims (1)

(57) [Claims] 1. A rubber composition comprising: (A) 50 to 99% by weight of a polypropylene resin; and (B) 1 to 50% by weight of a rubber component, wherein the rubber component (B) comprises: (i) an ethylene content of 60 to 95 mol%; MFR _{230 ℃} 0.1〜5
An ethylene-based random copolymer selected from a random copolymer of 0 g / 10 min of ethylene and an α-olefin having 3 to 20 carbon atoms; (ii) 1-butene content of 60 to 99 mol%, MFR _{230 ° C} 0.1
1 to 50 g / 10 min 1-butene and 2 carbon atoms excluding 1-butene
And a 1-butene random copolymer selected from random copolymers with α-olefins having a weight ratio of 95: 5 to
A polypropylene resin composition comprising a random copolymer composition containing 5:95.