JP2890794B2 - Inorganic filled polyolefin resin composition and use thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inorganic-filled polyolefin-based resin composition used as a material for lids and caps of containers for foods, detergents and the like, and uses thereof.

More specifically, the present invention relates to an inorganic-filled polyolefin-based resin composition used as a material for a lid or a cap having a hinge portion and a portion for tearing a thin portion with a zipper or a knob, and its use.

<Prior Art> A lid or cap of a container for food, detergent, etc., particularly a lid or a cap having a hinge portion and a portion for tearing a thin portion with a zipper or a knob, is made of high-pressure low-density polyethylene or ethylene-α-olefin. Polymer resins are used.

Recently, development of an easily incinerated resin with a low calorific value has been demanded due to environmental problems.

In order to reduce the calorific value, it is known to mix an inorganic filler, but when an inorganic filler is added to a conventionally used high-pressure low-density polyethylene or ethylene-α-olefin copolymer resin, the elongation increases. Degraded and cannot be used as a practical product.

<Problems to be Solved by the Invention> An object of the present invention is to provide a material such as a lid or a cap that has good elongation and a good balance between the tear strength of a hinge portion and the strength of a portion that tears a thin portion with a zipper or a knob. An object of the present invention is to provide an inorganic-filled polyolefin-based resin composition used as a resin and its use.

In a molded article such as a lid or a cap having a hinge portion and a zipper or a portion that tears a thin portion, that is, the tear strength of the hinge portion is preferably higher, but the tear strength of a portion that tears the thin portion with a zipper or a knob is lower. Therefore, a good balance between the two is required.

<Means for Solving the Problems> The present inventors have intensively studied to improve the elongation, balance the tear strength of the hinge portion, and the strength of the portion that tears the thin portion with a zipper or a knob, and as a result, have found that specific ethylene- An inorganic-filled polyolefin resin composition with good elongation by combining an α-olefin copolymer resin, polypropylene and an inorganic filler, thereby achieving a good balance between the tear strength of the hinge portion and the strength of the portion where the thin portion is torn by the zipper or knob. Product and its use have been found.

That is, the present invention relates to (A) melt flow rate (load is 2.
16kg, measured at 190 ° C) 4 ~ 50g / 10min, density is
0.910 g / cm ³ or less, the maximum melting peak temperature by differential scanning calorimetry (DSC) is 100 ° C. or more, and the heat of fusion at 100 ° C. or more by DSC is 10 joules / g or more. 10 to 60 parts by weight of olefin copolymer resin, (B) melt flow rate (load 2.16 according to JIS-K7210)
kg, measured at a measurement temperature of 230 ° C.) 5 to 100 g / 10 minutes, polypropylene 10 to 60 which is a random copolymer containing 10% by weight or less of ethylene or a block copolymer containing 15% by weight or less of ethylene. The present invention relates to an inorganic-filled polyolefin-based resin composition characterized by containing 25 parts by weight and (C) 25 to 45 parts by weight of an inorganic filler.

However, the total of (A), (B) and (C) is 100 parts by weight.

The present invention also relates to a lid or cap of a container having a hinge portion and a portion for tearing a thin portion with a zipper or a knob, comprising the inorganic-filled polyolefin-based resin composition.

Ethylene-α of component (A) used in the present invention
The olefin copolymer resin is obtained by polymerizing ethylene and an α-olefin having 3 to 18 carbon atoms using a transition metal catalyst.

The polymerization reaction is usually carried out at a polymerization temperature of 30 to 300 ° C., at a normal pressure to a polymerization pressure of 3000 kg / cm ² , in the presence or absence of a solvent, in a gas-solid, liquid-solid or homogeneous liquid phase. You.

As the α-olefin, propylene, butene-1,
4-methylpentene-1, hexene-1, octene-
1, decene-1 and the like are used, but those having 3 to 10 carbon atoms are preferred.

These α-olefins can be used alone or in combination of two or more.

Ethylene-α of component (A) used in the present invention
-The melt flow rate of the olefin copolymer resin is 4 g / 1
If the time is less than 0 minutes, the moldability is poor, and if it exceeds 50 g / 10 minutes, the impact resistance is poor.

If the density exceeds 0.910 g / cm ³ , the elongation decreases, and a good resin composition cannot be obtained. Preferably it is 0.880-0.908.

Maximum melting peak temperature by DSC below 100 ° C or DSC
If the heat of fusion above 100 ° C is less than 10 joules / g,
Not only is the rigidity significantly reduced, but also the heat resistance is inferior, so that it cannot be used as a practical material.

The polypropylene as the component (B) is preferably a random copolymer containing 10% by weight or less of ethylene, a block copolymer containing 15% by weight or less of ethylene, and the like.

The melt flow rate of the component (B) polypropylene is
If it is less than 5 g / 10 minutes, the moldability is poor, and if it exceeds 100 g / 10 minutes, the impact resistance is poor. Preferably it is 10 to 50 g / 10 minutes.

The inorganic filler of the component (C) is an inorganic powder that can be filled in a polyolefin-based resin, for example, calcium carbonate,
Aluminum hydroxide, magnesium hydroxide, calcium silicate, magnesium silicate, barium sulfate, talc,
Mica, silica, glass powder and the like can be mentioned, and calcium carbonate is particularly preferable.

The blending method for obtaining the resin composition can be performed by a usual mixing operation, for example, a Banbury mixer method or an extrusion granulation method.

Other additional components such as a neutralizing agent, a dispersing agent, an antioxidant, a weather resistance improving agent, an antistatic agent, and a pigment can be added to the resin composition within a range not to impair the effects of the present invention.

<Examples> Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 7, Comparative Examples 2 to 3 The component (A) ethylene-α-olefin copolymer resin and the component (C) inorganic filler shown in Table 1 were kneaded for 10 minutes at 120 ° C. using a Banbury mixer. Granulation was performed at 180 ° C. using a 65 mm diameter extruder.

The obtained pellets and the component (B) polypropylene shown in Table 1 were mixed in a tumbler blender for 30 minutes, granulated at 200 ° C. with a 30 mm diameter extruder, and injected with an injection molding machine (Toshiba Machine Co., trade name IS- 100EN) to make injection molded products and evaluate them. The results are shown in Table 2.

Comparative Example 1 The component (A) ethylene-α-olefin copolymer resin shown in Table 1 and the component (C) inorganic filler were kneaded with a Banbury mixer at 120 ° C. for 10 minutes, and 180 ° C. with a 65 mm diameter extruder. Injection molding machine (Toshiba Machine Co., Ltd., trade name IS-100E)
In N), injection molded products were made and evaluated. The results are shown in Table 2.

 The evaluation method is as follows.

(1) Melt flow rate JIS-K7210 (Load 2.16 kg) Measurement temperature Component (B) Polypropylene alone is 230 ℃,
Others were 190 ° C. (2) Density JIS-K6760 (3) Maximum melting peak temperature by DSC Using a Perkin Elmer Model 7 DSC, the maximum melting peak temperature was measured by JIS-K7121.

The condition of the test piece was adjusted according to JIS-K7121 3- (2).

(4) Heat of fusion at 100 ° C. or more by DSC Using a Perkin Elmer Model 7 DSC, the heat of fusion at 100 ° C. or more was measured according to JIS-K7122.

The condition of the test piece was adjusted according to JIS-K7122, section 3- (2).

The pellets before injection molding were used for evaluation of melt flow rate, density, peak melting temperature by DSC, and heat of fusion at 100 ° C. or higher by DSC.

(5) Flexural rigidity Using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., trade name IS-100EN), the cylinder temperature is 200 ° C, the injection pressure is 50-100 kg / cm ² ,
A flat plate having a thickness of 1.5 mm and a size of 150 × 150 mm was injection-molded under the conditions of a molding cycle of 45 seconds and a mold temperature of 40 ° C.

A test piece was cut out from the obtained injection-molded product and measured by ASTM D747.

(6) Tensile fracture strength, tear fracture elongation From the injection molded products used for the measurement of flexural rigidity, JIS-K
A No. 2 test piece was cut out according to 7113 and measured under the conditions of a tensile speed of 200 mm / min.

(7) Tear strength of thin section Using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., trade name IS-100EN), cylinder temperature is 200 ° C, injection pressure is 40 ~ 90kg / cm ² ,
Under the conditions of a molding cycle of 45 seconds and a mold temperature of 40 ° C., a flat plate having a thickness of 2 mm and a thickness of 60 × 80 mm having a thin portion of 0.2 mm at the center was injection-molded.

A test piece for tear test was cut out from the obtained injection-molded product according to JIS-K6301 and measured under the condition of a tensile speed of 200 mm / min.

If the tensile strength of the thin part is in the range of 5 to 8 kg, it is judged to be good.

<Effects of the Invention> As described above, according to the present invention, it has an appropriate rigidity, a tear strength of a thin portion, a good elongation, and is used as a material for lids and caps of containers for foods, detergents and the like. A suitable inorganic-filled polyolefin-based resin composition and its use can be provided.

Claims (3)

(57) [Claims] (A) a melt flow rate of 4 to 50 g / 10;
And a density of 0.910 g / cm ³ or less and a differential scanning calorimeter (DS
10 to 60 parts by weight of an ethylene-α-olefin copolymer resin having a maximum melting peak temperature of 100 ° C. or higher according to C) and a heat of fusion at 100 ° C. or higher according to DSC of 10 joules / g or more; A melt flow rate of 5 to 100 g / 10 minutes, 10 to 60 parts by weight of a polypropylene which is a random copolymer containing 10% by weight or less of ethylene or a block copolymer containing 15% by weight or less of ethylene; A) an inorganic-filled polyolefin-based resin composition comprising 25 to 45 parts by weight of an inorganic filler; However, the total of (A), (B) and (C) is 100 parts by weight. 2. The inorganic-filled polyolefin resin composition according to claim 1, wherein the inorganic filler is calcium carbonate. 3. A lid or cap for a container having a hinge portion and a portion for tearing a thin portion with a zipper or a knob, comprising the inorganic-filled polyolefin resin composition according to claim 1.