JPS58215436A - Polyethylene composition for thin-walled reinforcing film, said film and production of said film - Google Patents

Abstract

PURPOSE:A composition for high-density polyethylene thin-walled reinforcing films which is low in a motor load and an extrusion pressure during resin extrusion and is excellent in picking property, prepared by mixing high-density PE with a specified lubricant and a specified alkylamine derivative. CONSTITUTION:A polyethylene composition for thin-walled reinforcing films comprising (A) 0.05-0.70wt% at least one member selected from the group consisting of higher fatty acid salts and higher fatty acid amides, (B) 0.1- 0.3wt% alkylamine, m.p. <=40 deg.C, represented by the formula (wherein R is a fatty acid-forming 12-18C alkyl, and R1 is H or a fatty acid-forming 12-18C acyl) and (C) 99.85-99.0wt% high-density polyethylene, density >=0.940, melt flow rate <=0.15. This composition is low in a motor load and an extrusion pressure during resin molding, and can form high-density polyethylene thin-walled reinforcing films having extremely excellent picking property.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyethylene compositions for thin reinforced films, the production of said films, and said films. More specifically, it reduces the motor load and extrusion pressure during resin extrusion, and
The present invention relates to a composition for a high-density polyethylene thin reinforced film with extremely excellent opening properties, the film, and a method for producing the same.

In recent years, films produced by air-cooling inflation molding of high-molecular-weight, high-density polyethylene at high blow ratios are called thin-walled reinforced films, and their toughness and high rigidity allow them to be made thinner, making them useful in shopping bags, garbage bags, and standard manufacturing fields as resource-saving films. It is rapidly growing as an alternative to traditional kraft paper, low-density polyethylene film, etc.

The high-density polyethylene for this thin-walled reinforced film is ultra-high molecular weight high-density polyethylene of around 0.05 (Melt Flow Ray) used as the raw material resin, so there are steps such as forming the polyethylene powder into pellets, extruding the pellets and forming them into a film, etc. In the melt extrusion process, the motor load and extrusion pressure are extremely high, which is a major obstacle to improving productivity, and there is also a problem in that fish eyes increase due to crosslinked products generated due to high shear.

In addition, when using this thin reinforced film as a shopping bag or standard bag, even if the mouth of the bag is opened to fill the contents (products), the films attract each other and the mouth closes immediately, making it difficult to fill. The disadvantage was that the performance was significantly reduced. The present inventor has found that this poor opening property is caused by the charging (static electricity) of the polyethylene film. When molded, the surface becomes sticky due to bleed-out of the antistatic agent.
On the contrary, the opening property deteriorated, and this problem could not be solved simply by imparting antistatic properties.

As a result of various studies in order to improve the manufacturing and usage drawbacks of the conventional high-density polyethylene thin-walled reinforced film as described above, the present inventor has developed a high-molecular weight polymer containing a specific lubricant and a specific amount of an alkylamine derivative. A high-density polyethylene composition is used as a raw material, air-cooled inflation molding is performed at a high blow ratio, and both the upper and lower outer surfaces of the flattened tubular film are subjected to corona discharge treatment within a certain range of recesses, resulting in excellent extrusion processability. The inventors have discovered that it is possible to obtain a film with fewer fish eyes and excellent opening properties, and have thus arrived at the present invention. As is clear from the above description, the present invention aims to provide a composition for a high-density polyethylene thin reinforced film that has excellent extrusion processability and extremely excellent opening properties, a method for producing the film, and a method for producing the film. This is the purpose.

That is, the present invention consists of three inventions having the following three structures (1) to (3).

(1) ■ 0.05 to 0.70% by weight of one or more lubricants selected from higher fatty acid salts and higher fatty acid amides, prime number 1
2-18 fatty acid-forming alkyl group, R1 is hydrogen or a C12-18 fatty acid-forming acyl group),
and an alkylamine derivative 061~ with a melting point of 40°C or less
0.3% by weight and ■ High-density polyethylene with a density of 0.940 or more (melt flow rate) 0.15 or less 99.85~
6-Polyethylene composition for thin reinforced film consisting of 99.0% by weight.

(2) ■ One or more lubricants selected from higher fatty acid salts and higher fatty acid amides 0.05 to C", 70% by weight, prime number 12
~1B fatty acid-forming alkyl group, R1 is hydrogen or a fatty acid-forming acyl group having 12 to 18 carbon atoms), and has a melting point of 40°C or less, an alkylamine rust conductor 0.1 to 0
．． 3% by weight and ■ High-density polyethylene with a density of 0.940 or more (melt flow rate) 0.15 or less 99.85-9
A molten polyethylene composition for a thin reinforcing film containing 9.0% by weight is extruded through an annular die, and the diameter of the bubble formed by the extrusion is blown up to 2.5 times or more the diameter of the slit of the die, and then a stabilizer plate is formed. A thin-walled reinforced film characterized by subjecting both outer surfaces of the thus obtained flattened tubular film to a corona discharge treatment to obtain a wettability index of 35 to 43 dyne/ex. Film manufacturing method.

(3) ■ 0.05 to 0.70% by weight of one or more lubricants selected from higher fatty acid salts and higher fatty acid amides, prime number 12 to
18 fatty acid-forming alkyl groups, horse is hydrogen or fatty acid-forming acyl groups having 12 to 18 carbon atoms), and
Alkylamine derivative with a melting point of 40°C or less 0.1 to 0.3
weight% and ■density 0.940 or more melt flow rate)
High density polyethylene of 0.15 or less 99.85-99
．． A melt of a polyethylene composition for a thin reinforcing film containing 0% by weight is extruded from an annular die, and the diameter of the bubble formed by the extrusion is set to 2.0% by weight of the slit diameter of the die.
After blowing up 5 times or more, it is brought into contact with a stabilizer plate and folded, and both outer surfaces of the thus obtained flattened tubular film are treated with corona discharge to give a wettability index of 35 to 43 dynθ/σ. Thin reinforced film.

The polyethylene used in the present invention is an ethylene polymer having a density of 0940 or more and a melt index of 0.15 or less, or a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and among these, the polyethylene has a density of 0.945 to 0. , 955, melt flow rate) 0.02 to 0.08, flow register 2nd
Particularly preferred are 0-50 ethylene-butene-1 copolymers.

Among the lubricants added to polyethylene in the present invention, higher fatty acid salts include fatty acid salts of alkali metals or alkaline earth metals such as lithium stearate, calcium stearate, calcium 12-hydroxystearate, and magnesium stearate, zinc stearate, etc. can be,
Two or more of them may be added.

Examples of fatty acid amides include laurylamide, myristylamide, palmitylamide, oleylamide, stearylamide, and erucylamide, which are obtained by reacting a higher fatty acid having 12 to 22 carbon atoms with ammonia by a known method.

In the present invention, the amount of lubricant added to polyethylene is such that the total amount of one or more selected from higher fatty acid salts and higher fatty acid amides is ○ in the total composition. It should be in the range of 0.05-0.7% by weight. If it is less than 0.05 weight, the alkylamine derivative in the composition of the present invention will be poorly dispersed, and the shear during extrusion as polyethylene will be high, making high-speed extrusion impossible. On the other hand, if it exceeds 0.7 weight, it is not preferable because bubbles during film molding become unstable, and the lubricant bleeds onto the surface of the final film, reducing printability and heat sealability. In the present invention, 0
A very small addition range of 905 to 0.4% by weight is particularly preferred.

In the present invention, R has a carbon number of 1 as well as a specific lubricant for polyethylene.
Examples of the alkylamine derivatives having a melting point of 40° C. or lower and having a melting point of 40° C. or less include stearyl Tanolamine, myristylgetanolamine, palmityl 10-getanolamine, oleylgetanolamine, and alkylgetanolamine having an alkyl group for fatty acid formation obtained by hydrolysis of fats and oils such as coconut oil and beef tallow, oleylgetanolamine and monostearyl ester of oleyl jetanolamine. Among these, the most desirable are alkyl jetanolamines having a fatty acid-forming alkyl group obtained by hydrolysis of fats and oils such as coconut oil and beef tallow mixed with fatty acids having 12 to 1 carbon atoms.

Compositions of the above general formula can also be obtained with melting points exceeding 40°C, but those with melting points exceeding 40°C are extremely poor in improving the opening property of the film and cannot be put to practical use.

In the present invention, the amount of the specific alkylamine derivative added to polyethylene is 0.0 based on the weight of the total composition.
It is limited to a very small amount and narrow range of 5 to 0.3 weight. If it is less than 0.05%, no improvement effect will be obtained, and if it exceeds 0.3%, bubbles during film forming will become unstable, and the additive will bleed out to the film surface, causing severe damage to the film surface. is undesirable because it tends to stick and reduces the ability to open the mouth. Particularly preferably from 0.1 to
It is in the range of 0.25% by weight.

In order to prevent deterioration of the composition, it is desirable to add a known antioxidant to the polyethylene composition containing a specific amount of the specific lubricant and specific alkylamine derivative of the present invention. Agents, fillers, coloring agents, etc. may be added. Further, the kneading can be easily carried out using a commonly known mixing method such as a Banbury mixer, a Henschel mixer, or an extruder.

A polyethylene composition containing a specific lubricant and a specific alkylamine derivative of the present invention is melt-extruded from an extruder and a tubular die, blown up to a diameter of 2.5 times or more the diameter of the tubular slit of the die, and air-cooled. In this case, in order to obtain a film with superior strength, after maintaining the tubular body at a height of 300 degrees or more from the exit slit of the tubular die, the diameter of the tubular slit is approximately equal to the diameter of the slit of the die. It is desirable to rapidly blow up 2.5 to 6 times.

After blowing up and forming a film, the film is brought into contact with a stabilizer plate, folded, and then wound up as a flattened tubular film. In the present invention, both upper and lower outer surfaces of the flattened tubular film are coated with a wettability index of 35 to 35.
Corona discharge treatment must be performed to obtain 43 dynθ/cIL. When only one outer surface of the flattened tubular film was treated, or even when both upper and lower outer surfaces were treated, the wettability index was 35 dyne//.

If this is not achieved, the desired opening property will not be improved.

In addition, if the treatment is carried out at a strength exceeding 43 dyne/cm 2 , the additives will be decomposed, the improvement effect will be reduced, and the heat sealability of the film will also be reduced, which is not preferable.

In the case of 7'lkm for shopping bags, when folding and flattening the tubular film, the side gusset method is used to push in both ends of the film, double the ends, and roll it up to form a box-shaped bag. However, in this case, corona discharge treatment may be applied to both the upper and lower outer surfaces after the side gussets are applied and pushed in. In this case, the inner and outer surfaces of the pressed and doubled portion are not treated, but in the present invention, a film with a good opening can be obtained, and the result is completely different from the case where only one outer surface of the flattened film is treated. It's amazing what you can get.

The present invention improves the extrusion processability of high-molecular-weight high-density polyethylene, and produces polyethylene that has excellent filling workability for products with good opening properties and fewer fish eyes without reducing stability during film forming. This is a new technology that provides a composition, a polyethylene film, and a method for producing the same, and the same results can be obtained even if the high-density polyethylene of the present invention is replaced with crystalline polypropylene produced by a water-cooled inflation process or low-density polyethylene 14-ethylene produced by an air-cooled inflation process. It cannot be applied because it does not provide any effect and on the contrary worsens the ability to open the mouth. The above facts indicate the degree of difficulty in constructing the present invention. The features of the present invention are as follows:
A specific lubricant and a specific alkylamine derivative are blended into high-density polyethylene in extremely small amounts and within a limited range, and their synergistic effect improves film formability and improves both upper and lower properties of tubular films under specific conditions. Specific performance has been improved by combining external surface treatments, and it is expected to make a significant contribution to improving the film formability of shopping bags, general standard bags, etc., and improving bag filling workability. .

The present invention will be specifically explained below with reference to Examples and Comparative Examples.

In addition, each item was measured by the following method.

(1) Density, melt flow rate) (M engineering): J engineering S
K6760 (190℃, 2.16Kf) (2) Fo
-v y o (FR): JIEI K67600
M-work measurement 15 The M-work was measured using a 2.15Kp load and a load of 1α8゛ according to the method described above, and was determined from the following formula.

(3) Melting point (MP) 2J Engineering S K8004-19619
The melting point was measured using the second method for measuring the melting point of chemicals. However, the measurement was omitted for those exhibiting a liquid state at room temperature (23° C.).

(4) Wetting index: Measured within 2 hours after film forming by the method specified in J Engineering S K6'i'6B. (Unit: dyne/aIL) (5) Antistatic property: 10 KV was applied to the sample in an atmosphere of 23°C and 5o% RH using a static honest meter (Shishido Shokai IR) until the charged voltage of the sample reached saturation. After reaching the voltage, stop the application and calculate the charging voltage decay rate (unit:
%) hail.

(6) Openability of bags: After cutting the flattened tubular film into a certain size, only the bottom portion thereof was heat-sealed, and the openingability of the bags thus obtained was determined by the following method.

O Initial opening ability: A sensory test was conducted by rubbing the opening of the bag with one hand to open it. ○ indicates that the bag opens easily after rubbing 5 times or more, and 1 indicates that it does not open unless rubbed 5 times or more. Alternatively, cases where only the rubbed portion opened were judged as △.

O Improving filling workability After opening the bag, hold one side of the bag's mouth with one hand and use the other hand to fill the bag with a 5cIL square piece of Styrofoam. Items that allow you to easily fill the bottom of the bag with Styrofoam pieces with one hand are ○. Items that cannot be filled with one hand because when you open the bag and hold it with one hand, the films attract each other and the bag's mouth closes. A case where the mouth of the bag was open but more than half of the cross-sectional area of the bag mouth was closed, and a piece of Styrofoam could not be pushed into a trench was judged as △.

Examples 1 to 5, Comparative Examples 1 to 7 Density 0.950 f/(-d, M 0.07 f/
Phenolic antioxidant BIT 0.1 weight aS and Table-
Blend the additives shown in 1 and mix with a Henschel mixer.
The mixture was melt-kneaded and granulated at 270° C. using a 2-sealed extruder with a diameter of 65 mm. The obtained pellets were made into a diameter of 500φ.
extruder and a tubular die with a diameter of 500φ (lip clearance 1°Qm) with a screw rotation speed of 75.
extruded into a tubular shape at rpm1 extrusion temperature of 200°C, air-cooled,
After being blown up to a size of 3.5 times, it was folded and flattened while in contact with a stabilizer plate to obtain a flattened Tupler film. Both the upper and lower outer surfaces of this film were treated with corona discharge to produce a folded diameter of 27 mm.
A film with a thickness of 15 μm was produced. The extrusion resin pressure (measured at the head), resin extrusion amount, bubble stability, and film properties of the obtained film during film forming of each pellet obtained in this experiment are also listed in Table 1. In addition, in Table 1, both outer surfaces (surface-treated surfaces) of the Sokamensha tubular film and the inner surface of the charging voltage attenuation rate indicate the inner surface (non-surface-treated surface) of the tubular film. As is clear from Table 1, in the case of the present invention (Examples 1 to 5), film formability, film fisheye, initial opening property, and filling workability are all excellent, but Comparative Examples 1 to 7 In this case, there is a problem with any of the above physical properties and it is not preferable. In particular, when both outer surfaces of the tube are treated with corona discharge using the composition of the present invention, the untreated inner surface of the tube also exhibits antistatic properties, and its properties of excellent filling workability are unique. It is.

Examples 6-7, Comparative Examples 8-10 Density 0.945 f/(-d%M 0.05 t/
10 ml of ethylene-butene-1 copolymer powder with P 32℃)0
．． After blending 15% by weight and mixing in a Henschel mixer, 25% by weight was mixed using a 40fi extruder sealed with N2.
The mixture was melt-kneaded and granulated at 0°C. The obtained pellets were
Using a 0 m + 11 φ extruder and a tubular die with a diameter of 7581 φ (lip clearance 1.01011), the resin temperature was 200°C and the screw rotation speed was 90 rpm.
extruded into a tubular shape, and while air cooling, 50ffi from the top of the die.
The tubular body is maintained at a height approximately equal to the diameter of the die, and then rapidly expanded to 4.0 times the diameter of the die,
After that, the following (A), (B), (0), (D), (
Five types of tubular films having a fold diameter of 470 and a thickness of 25 were obtained by going through the five steps of E).

(A) The process of folding and flattening the obtained tubular film while contacting it with a bistable plate, then subjecting both the upper and lower outer surfaces of the obtained tubular film to corona discharge treatment and then winding it up (referred to as film A). (B) Contacting the bistable plate After folding and flattening the obtained tubular film, only one outer surface of the obtained tubular film is subjected to corona discharge treatment, and then winding up (referred to as film B). (C): After folding and flattening while contacting a stabilizer plate, The step of winding up the tubular film as it is (referred to as film C) (D): Folding the film while pressing both sides by 5α while contacting the stabilizer plate with the side gusset device attached (
After flattening (only both sides have a quadruple structure with a width of 5 cm and the other abdomen has a double structure), this gusset film is wound as it is (referred to as film D) (Ili): Step (■) above Then, the gusset films were subjected to corona discharge treatment on both the upper and lower outer surfaces, and then rolled up (referred to as film E).The bottoms of the five types of films obtained were heat-sealed to form bags with a length of 4C1+1. Table 2 shows the characteristics of each film. In Table 2, the treated surface refers to the corona discharge treated surface, and the non-treated surface refers to the opposite surface to the treated surface (note: in this case, since it is a tubular film, it is the inner surface in the case of external surface treatment), the untreated outer surface, and the untreated inner surface. indicates the outer and inner surfaces of surfaces that are not treated. Moreover, the untreated inner and outer surfaces of the film E are both side surfaces pushed in by side gussets.

As is clear from Table 2, the filling workability of Films A and I is extremely excellent.

23- 24- Examples 8-11. Comparative Example 11-18 The same high-density polyethylene powder used in Example 1 was blended with 2% by weight of BHTo as an antioxidant, 0.2% by weight of calcium stearate, and the additives shown in Table 3, and mixed in a Henschel mixer. Then, the mixture was melt-kneaded and granulated at a resin temperature of 250° C. using a Nippon Steel Shinsei C-M-5 twin-screw continuous kneading mixer sealed with N2. The obtained pellet was formed into a film in the same manner as in Example 1, and while adjusting the wetting tension to a predetermined wetting tension, both upper and lower outer surfaces were subjected to corona discharge treatment to produce a film having a fold diameter of 275 m and a thickness of 15 μm. The film formability and film properties of each pellet obtained in this experiment are also listed in Table 3. As is clear from Table 3, film formability depends on the type and amount of additive used and wetting tension.
The film properties are very different, and those within the scope of the present invention (Examples 8 to 11) are excellent in film formability, fish eyes, initial opening property, and filling workability. Also,
The opening properties of the film (initial opening properties, filling workability) are as follows:
It is observed that simply imparting antistatic properties to the film actually worsens the properties, and it is also clear that there is no necessarily correlation between the two properties.

Claims (3)

[Claims] (1) ■Lubricant selected from higher fatty acid salts and higher fatty acid amides 0.05 to 0.70% by weight, prime number 12 to
18 fatty acid-forming alkyl group, R1 dihydrogen or fatty acid-forming acyl group having 12 to 18 carbon atoms) and having a melting point of 40°C or less.
3% by weight and ■ High-density polyethylene with a density of 0.940 or more (melt flow rate) 0.15 or less 99°85-99
．． A polyethylene composition for a thin reinforced film comprising 0% by weight. (2) ■ 0.05 to 0.70% by weight of one or more lubricants selected from higher fatty acid salts and higher fatty acid amides, prime number 12 to
18 fatty acid-forming alkyl group, R1 is hydrogen or a fatty acid-forming acyl group having 12 to 18 carbon atoms), and has a melting point of 40C or less, an alkylamine derivative 0.1-0.
3% by weight and ■density 0.940 or higher (melt flow rate) 0.15 or lower high-density polyethylene 99.85-9
A molten polyethylene composition for thin reinforcing films containing 9.0% by weight is extruded from an annular die, and the diameter of the bubble formed by the extrusion is set to 2 times the diameter of the slit of the die.
．． After blowing it up to a size of 5 times or more, it is brought into contact with a stabilizing plate and folded, and the thus obtained flattened tubular
1. A method for producing a thin reinforced film, which comprises subjecting the outer surface of the cylinder of the film to a corona discharge treatment so that the wetting index of the object to be treated is 35 to 43 dynθ/a. (3) ■ 0.05 to 0.70% by weight of one or more lubricants selected from higher fatty acid salts and higher fatty acid amides, prime number 12 to
18 fatty acid-forming alkyl group, R1 is hydrogen or a fatty acid-forming acyl group having 12 to 18 carbon atoms), and an alkylamine derivative having a melting point of 40° C. or lower.
3 weight and ■density 0.940 or more melt flow rate)
High density polyethylene of 0.15 or less 99.85-99
．． A molten polyethylene composition for a thin reinforced film containing 0% by weight is extruded from an annular die, and the diameter of the bubble formed by the extrusion is set to 2 times the diameter of the slit of the die.
．． After blowing it up to a size of 5 times or more, it is brought into contact with a stabilizing plate and folded, and the thus obtained flattened tubular
A thin reinforced film obtained by subjecting both outer surfaces of the film to a corona discharge treatment to give a wetting tension of 35 to 43 dyne/cm.