JPH0517636A - Composition for inorganic-filled polyethylene film - Google Patents

Abstract

PURPOSE:To provide a composition which can give a polyethylene film excellent in paperlike texture and touch and printability and can be used for packaging bags, etc. CONSTITUTION:A composition comprising a high-density polyethylene which is a mixture of a high-density polyethylene of an MFR of 100-1500 and another high-density polyethylene of an MFR of 0.94-0.97, a low-density polyethylene of an MFR of 7 or below and a density of 0.93 or below, and calcium carbonate surface-treated with a higher fatty acid and having an average particle diameter of 0.5-6mum. This composition is highly filled with an inorganic filler, has surface smoothness excels in printability, has strength necessary for a packaging bag or the like, and is lowly calorific and easily burnable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic-filled polyethylene composition for a film, which is suitable for applications such as shopping bags used for packaging in supermarkets and department stores, household garbage bags, other packaging materials, agricultural materials and the like. It is a thing.

[0002]

2. Description of the Related Art Films obtained by blending high density polyethylene with an inorganic filler such as calcium carbonate are already known. It goes without saying that the characteristics of the film obtained differ depending on the characteristics of polyethylene, which is the main material, but in addition to this, the characteristics of the film obtained also differ depending on the filler to be compounded and filled. A composition for a film, which is limited to the one described above or whose filling amount is increased, has been proposed (Japanese Patent Publication No. 59-33138, etc.). These are intended to improve the impact strength and tear strength of the film, and to obtain a paper-like (paper-like) appearance and texture by mainly filling the inorganic filler in a high concentration.

[0003]

However, when the filler is filled in a high concentration, problems such as a weak heat seal strength and a decrease in film strength occur especially when the film is thin. Further, depending on the material of polyethylene and the type of the inorganic filler to be filled, the filler may drop as white powder from the surface of the film and stick to the hand. Therefore, such a film is not suitable for a shopping bag. In addition to this, while paper-like properties can be obtained,
The lack of surface lubricity causes problems such as poor workability and handleability. The present invention is capable of solving the above-mentioned problems, and an object of the present invention is to provide a polyethylene film having a required strength as a film, a paper texture, and a touch, and excellent printability. Is.

[0004]

The composition for an inorganic-filled polyethylene film of the present invention is characterized by comprising the following high-density polyethylene, low-density polyethylene and heavy calcium carbonate. a. High-density polyethylene ethylene-olefin copolymer (a) MFR of 100-1500, 30-70 parts by weight, preferably 40-60 parts by weight, and (b) MFR of 0.00015-0.2, 70- Three
A high density polyethylene comprising 0 parts by weight, preferably 60 to 40 parts by weight of a mixture, and having a mixture property of MFR: 0.03 to 0.7 density: 0.94 to 0.97. b. Low density polyethylene consisting of ethylene-α-olefin copolymer, α-olefin having 6 or more carbon atoms, MFR7 or less, density 0.9
Low density polyethylene of 3 or less. Amount: 5 to 70% by weight of the total composition c. Heavy calcium carbonate Surface-treated with higher fatty acid having 10 or more carbon atoms, average particle size: 0.5 to 6 microns, particle size upper limit value: 11 microns of heavy calcium carbonate. Filling amount: 20 to 60% by weight in the total composition

Each of the above components will be further described below.
Hereinafter,% indicates% by weight. a. The high-density polyethylene is the main component of the composition of the present invention, and is the MFR of the polyethylenes (a) and (b) above.
If the (melt flow rate) and the parts by weight of both are out of the range of the present invention, the film moldability and strength become poor, which is not preferable. The polyethylene mixture of the above (a) and (b) may be prepared by mixing polyethylene polymerized separately according to a conventional method, or may be produced by a two-stage polymerization method.

B. Low density polyethylene is ethylene-α
-Olefin copolymers having MFR and density within the above ranges are used. By compounding the composition in an amount of 5 to 70%, the heat-sealing strength, the impact strength, and the punch-out resistance to protrusions of the molded film can be improved. If the amount is less than 5%, the effect is small and 70
% Is not preferable because the tensile strength is lowered.
Low-density polyethylene is not preferable when the α-olefin in the component has less than 6 carbon atoms, because the impact strength of the obtained film decreases. Low density polyethylene having an MFR of 7 or more and a density of 0.93 or more reduces the tensile strength.

C. The heavy calcium carbonate is preferably surface-treated with a higher fatty acid having 10 or more carbon atoms. As the fatty acid, any of those commonly used in this type of field can be used, and among them, stearic acid is preferably used. The treatment method is performed, for example, by stirring and mixing calcium carbonate and higher fatty acid in a forced agitator while heating at 100 ° C. or higher. The surface treatment facilitates the dispersion of the filler in the composition to assist the filling, and
Improve the strength of the obtained film, improve the lubricity, etc.
Bring high quality. Those having an average particle size of 0.5 to 6 microns and not including a particle size larger than 11 microns are preferable. If the average particle size is 0.5 microns or less, it is difficult to disperse,
Coarse particles are likely to be aggregated with each other to form coarse particles, and an impact strength of 6 microns or more decreases. When the upper limit of the particle size is maintained at 11 μm or less, the film can be highly filled without lowering the heat-sealing strength, the surface slipperiness becomes high, and the white powder does not fall off. These effects of the upper limit of the particle size have not been known so far, and are based on the findings of the present inventor. If the filling amount is 20% or less, the compounding effect is insufficient, and if the filling amount is 60% or more, the strength of the film is lowered, which is not preferable.

The composition of the present invention comprises, in addition to the above components,
Additives and auxiliaries such as ultraviolet absorbers, antioxidants, colorants and the like which are usually added to polyethylene compositions can be added. Further, other polyolefins such as low density polyethylene (LDP) can be used as long as the characteristics of the present invention are not impaired.
E), LLDPE, EVA, ethylene propylene copolymer and the like can be blended. In addition, other surface treatment agents such as silane coupling agents, titanate coupling agents, higher fatty acids, higher fatty acid metal salts, and rosin can be used for calcium carbonate.

The compositions of this invention can be prepared by conventional means. That is, it is possible to use an Henschel mixer as a mixing and kneading means after heating and mixing, or an extruder treatment, or a Banbury mixer, a twin-screw extruder, or the like. The composition may be in the form of an ordinary commercially available product such as powder or pellet. The film can be formed by either general inflation molding or T-die molding.

[0010]

Since the high-density polyethylene film obtained by the composition of the present invention has sufficient heat sealing strength, it can withstand the packaging and transportation of heavy objects even if it is formed into a bag or the like.
Despite high filling, white powder does not fall off, has surface lubricity, and has well-balanced strength physical properties. Good moldability,
It has the advantage that uneven thickness, bubbles, pinholes, wrinkles, etc. are less likely to form on the molded film. In addition, since the film of the composition of the present invention has a large amount of calcium carbonate filled, it exhibits low calorie and is easily incinerated, and is suitable for waste incineration after use.

[0011]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Table 1 below
Further, with respect to each of the compositions of Examples and Comparative Examples described in Table 2, a film was molded by the following molding method, and its physical properties were measured to obtain the results shown in each table. The measuring method is as follows.

As can be seen from the results in the table, high density polyethylene (HDPE) and low density polyethylene (LLD)
PE) is the same as the present invention, but calcium carbonate (calcium charcoal)
The particle sizes of those other than the present invention and those not surface-treated are inferior to those of the present invention in physical properties such as heat seal strength.

Film forming method: inner diameter 60 mm, length / diameter (L
/ D): Using a 22 cylinder extruder, lip 1.2m
A cylindrical die with a diameter of 100 mm and a diameter of 100 mm was used. Extrusion temperature 190
Molded at ℃, blow ratio 4.0, frost line 500mm.

Particle size of filler: According to centrifugal sedimentation type particle size distribution analyzer (SA-CP3L) manufactured by Shimadzu Corporation.

Heat-sealing strength: The film after molding was heat-sealed with an impulse sealer. Seal part 10 mm
The test piece punched out to the width is opened to 180 ° and the tensile impact method (A
It was measured by STMD1822). (Unit: kg / cm /
10 mm)

Tensile strength and elongation at break: A strip-shaped test piece having a width of 10 mm and a length of 50 mm is pulled at a tensile speed of 500 mm / min, and is determined from the maximum load and the elongation at break. (Unit: kg / cm ² ,%)

Punching strength: A steel pin having a smooth end surface and a diameter of 2.5 mm is pressed at a rate of 500 mm / min from a direction perpendicular to a circular film having a diameter of 100 mm, and a load is applied until it penetrates. The breaking energy is calculated from the load-strain curve. (Unit: kg / cm / mm)

Loss Ca amount (quantity of white powder loss): 100 × 10
The 0 mm film is dipped in 10 cc of water, ultrasonic waves are applied for 60 seconds, and the Ca content released in water is measured. (Unit: pp
m)

Surface lubricity: According to the coefficient of friction measured according to JIS K7125.

[Table 1]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryoji Nishijima 11-2 Goi Minamikaigan, Ichihara-shi, Chiba Maruzen Polymer Co., Ltd. (72) Inventor Shozo Isobe 11-2 Goi Minamikaigan, Ichihara, Chiba Maruzen Polymer Within the corporation

Claims (1)

Claims: 1. A composition for an inorganic-filled polyethylene film comprising the following high-density polyethylene, low-density polyethylene and ground calcium carbonate. a. A high density polyethylene ethylene-olefin copolymer (a) having a MFR of 100 to 1500, 30 to 70 parts by weight, and (b) having a MFR of 0.00015 to 0.2, a mixture of 70 to 30 parts by weight, High-density polyethylene in which the properties of the mixture are MFR: 0.03 to 0.7 and density: 0.94 to 0.97. b. Low density polyethylene ethylene-α-olefin copolymer, α-olefin has 6 or more carbon atoms, MFR 7 or less, density 0.9
Low density polyethylene of 3 or less. Amount: 5 to 70% by weight of the total composition c. Heavy calcium carbonate Surface-treated with higher fatty acid having 10 or more carbon atoms, heavy calcium carbonate having an average particle diameter of 0.5 to 6 microns and an upper limit of particle diameter of 11 microns. Filling amount: 20 to 60% by weight in the total composition