JP2665843B2 - Composition for inorganic filled polyethylene film - Google Patents

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 suitable for use in shopping bags, household garbage bags, other packaging materials, agricultural materials and the like used for packaging in supermarkets and department stores. Things.

[0002]

2. Description of the Related Art Films in which high-density polyethylene is blended with an inorganic filler such as calcium carbonate are already known. Of course, the characteristics of the obtained film differ depending on the characteristics of the polyethylene which is the main material, but since the characteristics of the film obtained also differ depending on the filler to be blended and filled, the inorganic filler has a specific average particle size. There has been proposed a composition for a film which is limited to the one described above or has an increased filling amount (JP-B-59-33138). These are intended to improve the impact strength and tear strength of the film by filling the inorganic filler at a high concentration, and to obtain the appearance and texture of paper-like (paper-like).

[0003]

However, when the filler is filled at a high concentration, there arises a problem that the heat seal strength is weak or the film strength is reduced, particularly when the film is made thin. Further, depending on the material of the polyethylene and the type of the inorganic filler to be filled, a phenomenon such as the filler falling off the surface of the film as white powder and sticking to the hand may occur, and such a film is not suitable for a shopping bag. In addition, while paper-like properties can be obtained,
Insufficient surface lubricity causes problems such as lack of workability and handleability. The present invention can solve each of the above problems, and has an object to provide a polyethylene film having a required strength as a film, having a paper-like texture and feel, and having excellent printability. It is.

[0004]

The composition for an inorganic-filled polyethylene film of the present invention comprises the following high-density polyethylene, low-density polyethylene and heavy calcium carbonate. That is, a. High density polyethylene et styrene - 30-70 parts by weight that of O in the olefin copolymer (b) MFR 100 to 1500, preferably from 40 to 60 parts by weight (b) MFR ones 0.00015 to 0.2 70-3
A high-density polyethylene comprising 0 part by weight, preferably 60 to 40 parts by weight of a mixture, and the property of the mixture is MFR: 0.03 to 0.7, density: 0.94 to 0.97. Compounding amount: 10 to 75% by weight based on the total composition b. Low-density polyethylene: made of ethylene-α-olefin copolymer, α-olefin having 6 or more carbon atoms, MFR of 7 or less, density of 0.9
Low density polyethylene of 3 or less. Compounding amount: 5 to 70% by weight in the total composition c. Heavy calcium carbonate Heavy calcium carbonate that has been surface-treated with a higher fatty acid having 10 or more carbon atoms and has an average particle size of 0.5 to 6 microns and a particle size upper limit of 11 microns. Filling amount: 20 to 60% by weight based on the total composition

[0005] 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 the MFR of the polyethylene of (a) and (b) above
It is not preferable that the (melt flow rate) and the weight parts thereof both fall outside the ranges of the present invention, since the film formability and strength become poor. The polyethylene mixture of the above (a) and (b) may be prepared by mixing individually polymerized polyethylene according to a conventional method, or may be produced by a two-stage polymerization method.

B. Low density polyethylene is ethylene-α
-An olefin copolymer having an MFR and a density within the above ranges is used. By blending 5 to 70% in the composition, the heat sealing strength, impact strength, and punch-out resistance to protrusions of the molded film can be improved. If the content is less than 5%, the effect is small,
% Or more is not preferred because the tensile strength is reduced.
If the α-olefin in the component has less than 6 carbon atoms, the low-density polyethylene is not preferred because the impact strength of the obtained film is reduced. Low density polyethylene having an MFR of 7 or more and a density of 0.93 or more lowers 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 one commonly used in this kind of field can be used, and among them, stearic acid is preferably used. The treatment method is performed by, for example, stirring and mixing calcium carbonate and higher fatty acids while heating to 100 ° C. or higher in a forced stirrer. The surface treatment facilitates the dispersion of the filler in the composition and aids the filling,
It provides high quality, such as improving the strength of the obtained film and improving lubricity. Those having an average particle size of 0.5 to 6 microns and containing no particles larger than 11 microns are preferred. When the average particle size is 0.5 μm or less, it is difficult to disperse, and the particles are easily aggregated to form coarse particles. When the average particle size is 6 μm or more, the impact strength is reduced. The upper limit of the particle size is 1
If it is kept at 1 micron or less, high filling is possible without lowering the heat seal strength of the film, and the surface lubricity increases,
There is no shedding of white powder. 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 inventors. If the filling amount is less than 20%, the effect of the compounding is insufficient, and if it is more than 60%, the strength of the film is undesirably reduced.

[0008] In addition to the above components, the composition of the present invention comprises
Additives such as an ultraviolet absorber, an antioxidant, and a coloring agent, which are usually added to the polyethylene composition, and auxiliaries can be blended. Further, other polyolefins such as low-density polyethylene (LDP) may be used without impairing the characteristics of the present invention.
E), LLDPE, EVA, ethylene propylene copolymer and the like can be blended. In addition, other surface treatment agents such as a silane coupling agent, a titanate coupling agent, a higher fatty acid, a metal salt of a higher fatty acid, and rosin can be used for calcium carbonate.

The composition of the present invention can be prepared by usual means. That is, after heating and mixing with a Henschel mixer as a mixing and kneading means, an extruder, that is, a single screw extrusion.
Or a twin-screw extruder or a Banbury mixer . The composition can be in the form of a conventional commercial product such as a powder or a pellet. Film formation can be performed by any of general inflation molding and T-die molding.

[0010]

It is that off Irumu obtained by the present invention compositions according to the present invention, since the heat sealing strength is sufficient, be formed into a bag or the like able to withstand packaging and conveyance of heavy goods. Despite high filling, white powder does not fall off, has surface lubricity, and has well-balanced strength properties. Good moldability, uneven thickness in molded film,
It has the advantage that bubbles, pinholes, wrinkles and the like are hardly generated. Further, since the film made of the composition of the present invention has a large filling amount of calcium carbonate, it shows low calorie and easy incineration, and is suitable for incineration of waste 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
And for each composition of Examples and Comparative Examples shown in Table 2, a film was formed by molding method described below, the object of
To obtain a such results are measured in each table. In addition, 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 (charcoal)
Those having a particle size outside the scope of the present invention or having no surface treatment have inferior physical properties such as heat seal strength as those of the present invention.

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

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

Heat seal strength: The formed film was heat sealed with an impulse sealer. Seal part 10mm
The test piece punched to the width is opened at 180 ° and the tensile impact method (A
STMD1822). (Unit: kg ・ cm /
10mm)

Tensile strength and elongation at break: A rectangular 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 2.5 mm-diameter steel pin with a smooth end face is pressed at 500 mm / min from a perpendicular direction onto a film whose periphery is fixed in a circular shape having a diameter of 100 mm, and a load is applied until the pin passes through the pin. The breaking energy is determined from the load-strain curve. (Unit: kg · cm / mm)

Calculated shed Ca amount (quantification of shed white powder): 100 × 10
A 0 mm film is immersed in 10 cc water, and ultrasonic waves are applied for 60 seconds, and then the amount of Ca released in the water is measured. (Unit: pp
m)

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

[Table 1]

[Table 2]

Claims (1)

(57) [Claims] An inorganic-filled polyethylene film composition comprising the following high-density polyethylene, low-density polyethylene and heavy calcium carbonate. a. A high-density polyethylene ethylene-olefin copolymer comprising a mixture of (a) 30 to 70 parts by weight having an MFR of 100 to 1500 and (b) 70 to 30 parts by weight having an MFR of 0.00015 to 0.2; A high-density polyethylene in which the properties of the mixture are MFR: 0.03 to 0.7, density: 0.94 to 0.97. Compounding amount: 10 to 75% by weight based on the total composition b. Low-density polyethylene: made of ethylene-α-olefin copolymer, α-olefin having 6 or more carbon atoms, MFR of 7 or less, density of 0.9
Low density polyethylene of 3 or less. Compounding amount: 5 to 70% by weight in the total composition c. Heavy calcium carbonate Heavy calcium carbonate that has been surface-treated with a higher fatty acid having 10 or more carbon atoms and has an average particle size of 0.5 to 6 microns and a particle size upper limit of 11 microns. Filling amount: 20 to 60% by weight based on the total composition