JPS5929123A - Easily transverse-tearable inflation film - Google Patents

Abstract

PURPOSE:To provide an inflation film used in packing or the like, reduced in initial tearting resistance and tearting propagating resistance in a transverse direction while maintaining anti-tear strength in a longitudinal direction and excellent in tear linearity, comprising a composition containing an ethylenic polymer and an inorg. filler. CONSTITUTION:A compsition consisting of an ethylenic polymer with a melt index of 1.0g/10 or less and 10-30wt% inorg. filler (e.g., talc, clay, CaCO3 or the like) with an average particle size of 0.5-5.0m is subjected to inflation film formation to obtain an easily transverse-tearable inflation film with initial tear strength of 150kg/cm or less and Elmendorf tear strength of 15kg/cm or less. The film formation is performed by a method wherein the aforementioned composition is melted to be extruded from a die orfice to form a resin tubular body 2 which is, in turn, inflated from an inflation start point N. At this time, the relation (DB/DN)/(VB/VN) of the speed VN and the diameter DN of the tubular body 2 at the inflation start point N and the speed VB and the diameter VD of a bubble B after inflation is regulated to obtain predetermined transverse tearability.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the transverse direction can be easily torn by hand, and the lateral direction can be easily torn by hand.
The product is related to decomposable blown film.

What is an easy-to-tear 1'l blown film? When a blown film is torn by hand in the horizontal direction, the initial tearing resistance is extremely small, and the subsequent tear propagation resistance is also small, and the tear is easy! It is a blown film that has the function of being gentle and difficult to tear in the vertical direction, and is suitable for applications that require horizontal tearing, such as blowing (=J coating for cattle farming, film for agricultural use, and general packaging). It is useful for films, etc.

Traditionally, polyethylene, polyzolopyrene, etc.
J BW ヲY& The film obtained by making 11φ made of ordinary inflation has a low tear strength in the longitudinal direction.
It usually has a high tear strength in the transverse direction, so-called longitudinal tearability. To reduce the lateral tear strength,
Usually, a method is used to increase the expansion ratio (〕〕) and the pull diameter/die diameter, but this method results in a decrease in tear strength.
There are two points: the inability to obtain a 41G crack of 1/1, which satisfies C, and the fact that there is a limit to increasing the expansion ratio due to the 2-bull uncertainty during film formation. It is known that adding an inorganic filler to the resin reduces the tear strength of the film obtained, but in this case, in order to reduce the transverse tearability, it is necessary to fill the resin with a large amount of filler. (14 directions as well as vertical direction porcelain pulling strength is also low F)
]~, a suitable sacral fissure film cannot be obtained.

The object of the present invention is to create a tearable film that has low initial tear resistance and tear propagation resistance in the transverse direction while maintaining tear strength in the longitudinal direction, and has excellent tear resistance.
? It is to do Ijl. The inventors have discovered that this objective can be achieved by subjecting a specific resin composition to a specific inflation film forming method. That is, the gist of the present invention is to add an inorganic filler lO to an ethylene polymer having a melt index of less than 1.0 g/1.0 min and an average particle size of ()5 to -5, OIt.
The initial tear strength in the transverse direction is 150 k·'// rm or more, and the Elmendorf tear strength is 151'-97 or + pJ. So, a, le.

The above-mentioned initial tear resistance is the resistance at the beginning of tearing the cotton film, and the smaller this resistance is, the better the hand-tearability is. Tear?
/, the I-period resistance is determined by setting the test piece at a discontinuity [7] by -1-2 in the two-sided method of Elmendorf tear decoration. It was confirmed that the initial tear resistance (irI) corresponds well to the initial resistance when torn at 1" (7). Films with this value of approximately 100 to 7/c+n or less are easy to tear by hand. I feel that the initial resistance is extremely small.Tear propagation resistance is the tear resistance after the initial tear, and the smaller this resistance is, the less the tear direction is shifted by -1 in the vertical direction. .Tear propagation resistance id, JisZ] 702 Elmen 1゛It is determined according to the measurement method of ゛ tear strength.

Next, a method for manufacturing the tearable inflation film 1 of the present invention will be explained.

The ethylene polymer used in the present invention is a combination of ethylene heavy compound, ethylene-α olefin, ethylene-vinyl acetate, etc. (1//IO min JJ or lower is used. If the melt index is larger than 1.0, it becomes difficult to form a tubular body and stably form a film because the melt tension is small. Melt index is 1.
OJ-J, below, the smaller the melt index, the more Ill! ! ! D B
/ I) N At the same time, the VB/VJ described below is greatly changed to 1. However, if the melt index is less than 0.01, the extrudability of the extruder decreases, making it difficult to form a film. The ethylene polymer used preferably has a melt index of 0.1 to (1,03).

Kihatsu OIJ 1. <ζ Inorganic filler: f, 1 talc, clay.

Why)・Car+J? It is an inorganic powder with various shapes such as carbonate, carbonate, calcium silicate, titanium oxide, glass powder, mica, and kaolin, and has an average particle diameter of 0.5 to 5. Q It
They can be used alone or in combination.

When the average particle size of the filler is larger than 5.0 μm, the surface appearance of the film becomes hollow and the strength decreases by 7 bars (7.0 μm).
, which is not practical. When it becomes smaller than 05μ,
Transverse tear in film, l+! Initial tear resistance at 3t τJ
It becomes difficult to give. The preferred average particle size is
It is 0 to 3.0 μC. If the amount of filler added to the ethylene polymer is less than 10%, the effect of lowering the initial tear resistance will be lost. 30
If it becomes thicker than heavy, it not only deteriorates the appearance of the film but also reduces the resistance to tear propagation in the lateral direction and
At 71 o'clock, longitudinal tear propagation (as the drop in 1 h resistance increases, the requirements for practical use increase) - undesirable.Resin compositions containing the above fillers may be thermally stabilized as necessary. Additives such as a lubricant, a coloring agent, and an ultraviolet inhibitor, and synthetic resins other than ethylene polymers can be blended within a range that does not adversely affect the transverse tearability.

Next, the film forming method will be explained with reference to FIG. First, the resin composition is melted in an extruder (not shown), and a tubular body of molten resin extruded from an annular die port is transferred while maintaining approximately the same diameter, and is expanded from an expansion starting point 3. Here, the speed of the tubular body l after extrusion is VD, its diameter is DD, and the expansion starting point N
The velocity of the tubular body 2 is VN, its diameter is DN, and the diameter after expansion is ζ
VB is the speed of Sol B.

Let its diameter be DB. VB is equivalent to the withdrawal speed, and D
i is calculated from the folding of the film, but it can be found by actual measurement. DN is actually measured by applying a caliper or the like to the tubular body at the starting point of expansion. VN is also a direct rotational speed it to the tubular body.
Measured by touching the I) D is considered to be the diameter of the die, the rotation, etc., and ■n is the diameter of the die, the lip gap of the die, and the extrusion h1.

The present invention relates to DB/DN and V++/in the above film formation.
It was found that the initial tear resistance and tear propagation resistance, which have a unique relationship with VN resistance and tear propagation resistance and are important factors governing transverse tearability, decrease inversely proportionally, and at the same time, the longitudinal tear resistance decreases inversely. If the tear propagation resistance is preferably set to 2 or more, and the product tear resistance increases, the stability of S-pull decreases and film formation becomes difficult.

There are two options: to reduce VB/VN, or to reduce VB/VN.

To increase DFI/DN, DB is determined by the product, so DN must be decreased. To reduce DN, either reduce Mll of the ethylene polymer, or
#? Increase the lip gap of Gui? January r1
Methods such as lowering the length of the crystal or increasing the take-up speed during film formation, or weakening the cooling by the air ring C to increase the length of the tubular body are taken. The trap of reducing Vn/Vs is to increase VN since VB is determined by the product. VN can also be changed depending on the diameter and lip gap of the goo, the viscoelasticity and temperature of the molten resin, the extrusion speed during film formation, the degree of cooling of the tubular body by the air ring C, etc. How to easily troll VN 217σ,
0'', the length k of the tubular body from the gou exit to the first stretching start point N was determined by adjusting the air volume or wind speed of the air cooling by the air ring C to the tubular body 1. VN can be increased by lengthening the tubular body. Further, vN can also be increased by lowering the density of the molten resin during extrusion or by increasing the extrusion rate to increase the withdrawal speed. In addition, M of the ethylene polymer used
The lower I is, the larger VN is.

If it is kept constant, it is possible to consistently produce a film with a constant transverse tearing property of 9f with good reproducibility, and it is possible to match the same.

According to the present invention, a tearable film having a thickness of 8 to 100 μm can be produced. The effects of the present invention can be applied to bamboo in the production of thin films of 8 to 30 μm.

Examples are shown below.

Example High-density polyethylene (Nandek F18 manufactured by Asahi Kasei Corporation)
0, melt index 0.06!7'/10 min, density 0.9 s 4 El/ad) to it'-average particle size 1.5
A resin composition containing 50% by weight of μ calcium silicate powder was prepared, and this was dry blended with the upper layer of high-density polyethylene to give a filler concentration of 5.15.30% by weight. A resin composition was obtained. Next, high-density polyethylene without each resin composition and filler was extruded at a rate of 10 Kp/I ( , Gui exit resin 6 constant 21
It was extruded to a temperature of 0°C. and expansion ratio (BUR)
4.5, take-up speed 31 m, /min and -'1
Films were formed by changing the length of the tubular body. The velocity VN and diameter DN at the starting point of expansion of each tubular body are determined by side force,
9 of each t]; Margin Example 50 layers of heavy calcium carbonate powder with an average particle size of 2 p are mixed with high-density polycodylene (Sanatsuku F180) (
, a resin composition 1 was prepared, and each was mixed with high-density polyethylene and dry plain to give a filler concentration of 5.15.
．． : (A resin composition of 0.40'il silk 1% eζ was obtained. Next, each resin composition was
φ extruder, 125 open φ Rii (Rino Gyatso 12 questions) inflation hand November momme with IC, busy 1 fat temperature 2
25°C, extrusion at 40 to 51/h,
Expansion ratio 45, take-up speed '17+4/1n1110
When forming a film under different conditions, the resin temperature and the cooling rate of the tubular body were varied to increase the velocity and thickness of the tubular body at the starting point of expansion.
A 0μ film was obtained. The transverse tearing of each film to the second person! The results are shown below. The methods for measuring initial tear resistance, tear propagation resistance, and tear linearity were the same as in Example 1.

Example 3 In Example 1, a resin composition was formed into a film by blending a mixture of calcium silicate with an average particle size of 15 μm and heavy calcium carbonate with an average particle size of 2 μm into high-density polyethylene at different mixing ratios as a filler. . The transverse tearability of the obtained film is shown in the third layer.

bottom margin

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the film forming situation of the present invention. L... Tubular body immediately after extrusion, 2... Tubular body at expansion start point, B... Bubble after expansion, C... Cooling ring, D ...Thyroid die, N...Start point of expansion b4, 1) B...B point?
Pull diameter, Vn... Speed at point B, DI)...
Diameter of card body l, VD... Speed of tubular body 1, DN
... Diameter of tubular body 2, VN ... Card body 2
speed of. Patent applicant: Asahi Kasei Industries, Ltd. Figure 1

Claims (1)

[Claims] An inorganic filler with an average particle size of 05 to 50μ is added to an ethylene polymer with a melt index of 1.05'/l0JJ or less.
It is made of a composition containing 30% by weight and has an initial tear strength in the transverse direction of 150 K9/'cm J9 or less, and an Elmendorf tear strength of 15 to 9/Lyn or less -j
Easy 4 yellow tear resistant blown film