JPS6189828A - Manufacture of paper-like film - Google Patents

Abstract

PURPOSE:To enable to manufacture paper-like film suitable for manufacturing square bottom paper bags through utilizing composition consisting of high- density polyethylene, isotactic polypropylene and talc. CONSTITUTION:The title paper-like film is manufactured by inflation method from composition consisting of 40-90wt% of high-density polyethylene, 5-40wt% of isotactic polypropylene and 5-40wt% of talc. If the density of the high- density polyethylene is below 0.940g/cc, the nerve of the resultant film is not sufficient. If the amount of the high-density polyethylene is below 40wt%, the stable molding conditions can not be obtained, while if exceeds 90wt%, the elongation of the resultant film is larger, resulting in deteriorating its folding characteristics. The isotactic polypropylene improves the nerve of the film due to the synergistic action with the high-density polyethylene. However, if the amount of the isotactic polypropylene is below 5wt%, the nerve of the resultant film is not sufficient. In addition, if the amount of the talc is below 5wt%, the nerve of the resultant film is not sufficient and its paper-like feeling is not satisfactory.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for producing a paper-like film suitable for making square-bottomed bags by an inflation method.

PRIOR TECHNOLOGY In general, square bottom bags are made of paper and are widely used in various fields, but recently, as inflation film is inexpensive and can be mass-produced, attempts have been made to manufacture square bottom bags using synthetic resin film. ing.

There are various methods for manufacturing films by zunflation, but %21/(a), (b), (
As shown in a), a cylindrical bubble stabilizer 3 having a diameter smaller than the diameter of the resin extrusion slit 2 is protruded from the center of the surface of the die 1, and a large amount of air is ejected from the air ring 4. Extrude the at fat from the bubble 5 into the stabilizer 3.
The n-neck portion 5a of the neck is brought into contact.

Then, a method of expanding, crystallizing with a 70-strain line 5b, taking it up with nip rolls (not shown), folding it, and winding it up (CfF Kosho 55-2180) was developed.

It has become possible to produce a film with productivity of <17I and a well-balanced stretching ratio in the transverse direction.Problems with the Prior ArtHowever, polyolefin resins generally used in the 1-inflation method Films made from paper have a lower stiffness than paper, so they do not stick well to gripping tools during the bag-making process, and are not suitable for folding. Because of its high % tear strength, it was difficult to cut and was slippery (unsuitable for use in the manufacture of square-bottomed bags instead of paper).

Purpose of the Invention In view of the above circumstances, the present invention provides a paper-shaped bag suitable for making square bottom bags.
The purpose of the present invention is to provide a method for manufacturing a rubber film.

Structure of the Invention The present invention was made to achieve the above-mentioned object, and its gist is that high-density polyethylene: 40-90% by weight, isotactic polypropylene: 5-40% by weight.
When manufacturing a tar film by the inflation method using a composition consisting of talc: 5 to 40 weight ft41, the resin is melted and extruded through a die slit having grooves in the flow n direction on the outer circumferential surface of the mandrel. The method for producing a paper-like film includes protruding a puzzle stabilizer, bringing the neck of a bubble into contact with the stabilizer by a nm length, and then taking it off while expanding it.

The resin used in the method for producing a paper-like film according to the present invention is high-density polyethylene, isotactic polypropylene,
In the composition made by Merck, high-density polyethylene has a density of 0.940) / 40 to 90% by weight, preferably 50 to 70% by weight, and isotactic polyethylene has a density of 5 to 40% by weight. , preferably 10 to 25 weight percent, Merck.

It is blended at a ratio of 5 to 40% by weight, preferably 10 to 20% by weight.

If the density of high-density polyethylene is less than 0.940 t/cc, the stiffness of the film will be insufficient - if the amount is less than 40% by weight, the molding stability will be broken, and if it exceeds 90% by weight, the film will elongate and fold. The tatami characteristics deteriorate. Note that the melt index is 0. O1-3? /10 min is preferable % 0.015' / less than 10 m 1n A force that increases the stiffness of the film due to the interaction with the density polyethylene. The film strength becomes weaker when the weight exceeds 40 layers.The flow rate is 3~! 5 P710m
In is preferable, and if it is less than 3y-/10 min, the waist will become stiffer. , 15 to 710 min, the film strength deteriorates.

Furthermore, talc roughens the surface of the film to give it a paper-like texture and increases its stiffness, but if it is less than 5%, the stiffness and paper-like texture of the film will be insufficient. If the tensile strength is exceeded, the tear strength decreases and becomes unusable.

An example of an apparatus for making a blown film using the above composition is shown in Figure 1 (a), (1)), and the same parts as in Figures 2 (a), (b), and (c) are denoted by the same reference numerals. , and the explanation thereof will be omitted.

FIG. 1(a) is a partially enlarged plan view of the die 1, showing the outer peripheral surface of the mandrel 6 forming the die slit 2'.

Concave grooves 7 extending in the flow direction are provided at predetermined intervals. Therefore, through this die slit 2', melt extrusion n
A large number of longitudinal protrusions are formed on the inner surface of the resin composition tubular body. The film is expanded to form a capsule while retaining these protrusions.The recesses between the protrusions are mainly stretched.The strength of the film as a whole in the longitudinal direction is reduced, but bubbles are stabilized on the surface of the die. Since the body protrudes, the constriction portion 5a of the bubble 5 comes into close contact with the bubble 5, thereby stabilizing the bubble 5 and flattening the uneven surface of the foam to a certain extent, allowing it to expand almost uniformly. Although there is a possibility that traces of ridges or striped patterns may remain after setting, the vertical streaks of the history of ridges remain, and the vertical independence is the same as above.7? A strong film can be obtained.

In other words, as shown in Figure K1 (1)), the die slit 2
'The tubular resin in the eight ranges in which a large number of protrusions are formed on the inner surface by the extruded n% concave grooves 7... is brought into close contact with the bubble stabilizer 3 at the constricted portion 5a, and the bubble is stabilized. At the same time, the protrusions become flat to some extent while leaving a history of vertical stripes, and are expanded at a predetermined ratio within the range of 9 from n1 frost line so to nx.

It solidifies to form a paper-like film.

By providing the grooves on the mandrel as described above, the appearance of the film after bag making is more convenient than when the grooves are provided on each bag.

The physical properties of this composition and the effect of the history of the convex stripes make it suitable for making square bottom bags.

Examples and Comparative Examples [Examples 1 to 5] High-density polyethylene with a density of 0.940 or more, melt flow rate) isotactic polypropylene of 7.5P/10m1n, and talc in proportions within a predetermined range. The blended composition is applied to the outer peripheral surface of the mandrel at a depth of c: o, 5.
Ubllllll, OIu+ V-shaped flow n-direction groove 24
Mandrel outer diameter (non-groove part) with 0 wood t' 59
131φ1 die with 1 slit with an inner diameter of 60Rxφ
A die with a cylindrical bubble stabilizer with an outer diameter of 55JEXφ and a height of 700U protruding from the center of the surface is attached.
65 J! Using xφ extruder.

Blow ratio: 3. Take-up speed: 80 intervals/min, thickness near 0
Create a μm blown film.

Height 350suc x 72 2Q□usX width 150Ul
A manufacturing test was conducted on square bottom bags.

[Comparative Examples 1 to 3] A die slit was made using a normal smooth annular die slit with no grooves on the outer surface of the mandrel, and a mold was prepared under exactly the same operating conditions as in the examples, and was subjected to a test.

[Comparative Examples 4 to 9] Films were created under exactly the same operating conditions as in the examples, except that the density of high-density polyethylene, the blending ratio, and the blending ratio of isotactic polypropylene and talc were partially outside the predetermined ranges. Test results of Examples and Comparative Examples are shown in Table aE1.

As is clear from the table, the paper film produced by the method according to the present invention is extremely suitable for manufacturing square bottom bags.
Effects of the Invention As described above, the method according to the present invention improves the vertical independence on a somewhat rough surface and has strong stiffness.

Since it is possible to create a film that has properties similar to paper, it is possible to replace paper products with a synthetic resin film, and the field of its application is extremely wide.

[Brief explanation of the drawing]

! E111(a) and (b) are schematic explanatory diagrams of the paper-like film manufacturing method according to the present invention, and %IEI diagram (a) is a partially enlarged plan view of the die (@2 Figure (1)). )% Figure 1 (
fi) is a side view showing how a paper-like film is made using the die shown in Figure 1 (a), Figures 2 (a) and (b)
, (((ri) is a schematic explanatory diagram of the conventional blown film manufacturing method, Fig. 112 (a) is a side view, Fig. 2 (1)
')) is a thin cross-sectional view taken along line 1-1 of Figure 2C(a), and Figure 2(C) is a cross-sectional view taken along line 1'-1' of Figure 2(a). 1...Dice, 2'...Die slit %3...Bubble stabilizer (stable body), 5...
...Pulp, 5a...Neck part, 5b...
...Frost line, 6...Mandrel%
7... Concave groove. Figure 1 (G) 1 (b) Figure 2

Claims (1)

[Claims] High-density polyethylene: 40-90% by weight, Isotactic polypropylene: 5-40% by weight, Talc: 5-90% by weight
When producing a film by the inflation method using a composition consisting of 40% by weight, the resin is melt-extruded through a die slit having grooves in the flow direction on the outer peripheral surface of the mandrel, a valve stabilizer is protruded from the die surface, and A method for producing a paper-like film, which comprises bringing the constriction of a bubble into contact with a stabilizer and then taking it off while expanding it.