JP2011194642A - Method of manufacturing polyethylene film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a polyethylene film suppressing flickering.SOLUTION: In the method of manufacturing the polyethylene film, a polyethylene melting film extruded from a T die by melting and kneading ethylene-α-olefin copolymer satisfying the following requirements (A) and (B) by an extruder is nipped between a cooling roll having 0.5 μm or less of arithmetic mean roughness (Ra) on the surface and a pressing roll in which at least the surface is made of rubber: (A) flow activation energy (Ea) is set to be 40-100 kJ/mol; and (B) in the condition of 190°C, η/ηwhich is a ratio of melting complex viscosity ηmeasured at 0.1 rad/second of angular frequency to melting complex viscosity ηmeasured at 100 rad/second of angular frequency is set to be 10-100.

Description

  The present invention relates to a method for producing a polyethylene film.

  Liquid crystal displays such as mobile phones and liquid crystal televisions, optical film products used for CDs and DVDs, metal plates such as aluminum and stainless steel used for industrial and architectural purposes, synthetic resin plates such as acrylic and engineering plastics, wood decorative plates For articles such as, prevent the article from being scratched by contact or friction with the object during processing, storage, or transportation of the article, or prevent the surface of the article from becoming dirty due to dust adhesion, etc. Therefore, a surface protective film is affixed to the article.

As the surface protective film, a multilayer film having a base material layer and an adhesive layer, a film obtained by applying an adhesive to a single layer base material film, or the like is used. As the multilayer film, a polyolefin resin is often used as a base material layer, and an ethylene-vinyl acetate copolymer resin or an ethylene-α-olefin copolymer resin is often used as an adhesive layer. In addition, as the single-layer base film, a polyolefin resin, a polyvinyl chloride resin, or a polyethylene terephthalate resin is often used, and is properly used depending on the intended use. Further, acrylic, rubber or the like is used as the adhesive.

As a method for producing the surface protective film, for example, low-density polyethylene is melted with an extruder (set temperature: 200 ° C.) as a base layer resin, and linear low-density polyethylene is set as an adhesive layer resin with an extruder (set temperature: 240). And a co-extrusion method from a T die (set temperature 210 ° C.) is known (see, for example, Patent Document 1).

JP-A-5-229082

However, the film produced by the above production method sometimes causes flicker.
Under such circumstances, the problem to be solved by the present invention is to provide a method for producing a polyethylene film in which flicker is suppressed.

That is, the present invention provides a polyethylene melt film obtained by melt-kneading an ethylene-α-olefin copolymer satisfying the following requirements (A) and (B) with an extruder and extruding from a T die.
This is a method for producing a polyethylene film that is sandwiched between a cooling roll having a surface arithmetic average roughness (Ra) of 0.5 μm or less and a pressing roll having at least a surface made of rubber.
(A) Flow activation energy (Ea) is 40 to 100 kJ / mol
(B) Ratio of melt complex viscosity η * _0.1 measured at an angular frequency of _0.1 rad / sec and melt complex viscosity η * ₁₀₀ measured at an angular frequency of 100 rad / sec at 190 ° C. ,
η ^* _0.1 / η ^* ₁₀₀ is 10 to 100

  The present invention can provide a method for producing a polyethylene film in which flickering is suppressed.

Examples of the ethylene-α-olefin copolymer in the present invention include copolymers of ethylene and one or more α-olefins having 3 to 12 carbon atoms. Examples of the α-olefin having 3 to 12 carbon atoms include propylene, 1-butene, 1-pentene, 4-methylpentene-1, 1-hexene, 1-octene, 1-decene and the like. Among these, it is preferable to use propylene, 1-butene, 1-hexene, and 1-octene, and it is more preferable to use 1-butene and 1-hexene.

Examples of the ethylene-α-olefin copolymer include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-4-methylpentene-1 copolymer, an ethylene-1-hexene copolymer, Examples thereof include an ethylene-1-octene copolymer and an ethylene-propylene-1-butene copolymer. Among these, it is preferable to use ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, and ethylene-1-butene copolymer. It is more preferable to use an ethylene-1-hexene copolymer or an ethylene-1-butene-1-hexene copolymer.

The density of the ethylene -α- olefin copolymer in the present invention, the handling of the film, from the viewpoint of enhancing the releasability from the adherend, preferably not more than 880 kg / m ³ or more 960 kg / m ^3, more preferably Is 900 kg / m ³ or more and 940 kg / m ³ or less. The density is measured according to the method defined in Method A of JIS K7112 (1999) after annealing described in JIS K6760-1995.

  The melt flow rate (MFR) of the ethylene-α-olefin copolymer in the present invention is preferably 0.01 to 300 g / 10 minutes, more preferably 0.05 to 100 g / 10 minutes, and still more preferably 0.1. ~ 30 g / 10 min. In addition, this MFR is measured on condition of temperature 190 degreeC and load 21.18N in the method prescribed | regulated to JISK7210-1995.

The flow activation energy (Ea, unit is kJ / mol) of the ethylene-α-olefin copolymer in the present invention is 45 to 100 kJ / mol. Ea is preferably 50 kJ / mol or more, more preferably 55 kJ / mol or more, still more preferably 60 kJ / mol or more, and even more preferably 65 kJ / mol or more. Ea is preferably 100 kJ / mol or less, more preferably 90 kJ / mol or less.

The ratio η ^* _0.1 / η ^* ₁₀₀ of the melt complex viscosity (η ^* ) of the ethylene-α-olefin copolymer used in the present invention is 10-100. η ^* _0.1 / η ^* ₁₀₀ is preferably 15 to 90, more preferably 20 to 80, and still more preferably 25 to 70. The melt complex viscosity is measured at a measurement temperature of 190 ° C. using a viscoelasticity measuring device (for example, Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics). η * _0.1 is the melt complex viscosity measured at an angular frequency of _0.1 rad / sec, and η * ₁₀₀ is the melt complex viscosity measured at an angular frequency of ₁₀₀ rad / sec.

  To the ethylene-α-olefin copolymer used in the present invention, additives such as an antioxidant, a lubricant, an antistatic agent, and an antiblocking agent are added as necessary within a range not impairing the effects of the present invention. Also good. Moreover, you may use together resin different from the said ethylene-alpha-olefin copolymer.

  The present invention relates to a cooling roll in which an arithmetic average roughness (Ra) of a surface of a polyethylene molten film obtained by melting and kneading the above-described ethylene-α-olefin copolymer with an extruder and extruding from a T-die is 0.5 μm or less. And a method for producing a polyethylene film that is clamped by a pressing roll having at least a surface made of rubber.

  The polyethylene molten film may be a single layer or a multilayer. In the case of multiple layers, at least one layer may contain the ethylene-α-olefin copolymer. From the viewpoint of adhesiveness, the layer in contact with the cooling roll preferably contains the ethylene-α-olefin copolymer.

  In the present invention, the temperature of the polyethylene molten film immediately after being extruded from the T-die is preferably 200 ° C. or higher, and preferably 240 ° C. or higher, from the viewpoints of workability and reducing the number of fish eyes in the film. More preferably, it is 270 ° C. or higher. Moreover, from the viewpoint of suppressing the deterioration of the resin and from the viewpoint of reducing the cooling roll contamination by the smoke generating component, the temperature is preferably 350 ° C. or lower, and more preferably 340 ° C. or lower.

  The linear pressure when the polyethylene molten film is sandwiched between the cooling roll and the pressing roll is preferably 15 to 35 kN / m, and preferably 18 kN / m or more from the viewpoint of reducing the number of fish eyes, From the viewpoint of uniformly crimping, it is preferably 32 kN / m or less.

  The surface temperature of the cooling roll and the pressing roll is preferably 30 ° C. or more lower than the melting point of the sandwiched resin, and more preferably 50 ° C. or more.

In the present invention, a cooling roll having a surface arithmetic average roughness (Ra) of 0.5 μm or less is used. The cooling roll is preferably made of metal.
In addition, Ra is measured by the method prescribed | regulated to JISB0601-1994.

  The pressing roll used in the present invention has at least a surface made of rubber. Examples of the rubber include commercially available rubbers such as silicon rubber and neoprene rubber. The surface hardness of the pressing roll is preferably 60 to 95. The hardness is measured by a method defined in JIS K6253.

  The polyethylene film obtained by the method of the present invention is excellent in transparency and adhesive stability, so that it is a liquid crystal display such as a mobile phone or a liquid crystal television, an optical film product used for CD or DVD, a metal plate such as aluminum or stainless steel. It is preferably used for surface protection of synthetic resin plates such as acrylic and engineering plastics, and wood-made decorative plates. The thickness of the polyethylene film of the present invention is preferably 7 to 600 μm, more preferably 10 to 500 μm, and still more preferably 15 to 300 μm.

Hereinafter, the present invention will be described by way of examples.
The physical properties in the examples were measured according to the following methods.

(1) Density (Unit: kg / m ³ )
It measured according to the method prescribed | regulated to A method among JISK7112-1980. The sample was annealed according to JIS K6760-1995.

(2) Melt flow rate (MFR, unit: g / 10 min)
According to the method defined in JIS K7210-1995, the measurement was performed by the A method under the conditions of a load of 21.18 N and a temperature of 190 ° C.

(3) Flow activation energy (Ea, unit: kJ / mol)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), a melt complex viscosity-angular frequency curve at 130 ° C., 150 ° C., 170 ° C. and 190 ° C. was measured under the following measurement conditions. From the obtained melt complex viscosity-angular frequency curve, calculation software Rhios V. The activation energy (Ea) was determined using 4.4.4.
<Measurement conditions>
Geometry: Parallel plate Plate diameter: 25mm
Plate spacing: 1.5-2mm
Strain: 5%
Angular frequency: 0.1 to 100 rad / sec Measurement atmosphere: Under nitrogen

(4) Melt complex viscosity (η *, unit: Pa · sec)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), a melt complex viscosity-angular frequency curve at 190 ° C. was measured under the following measurement conditions, and the melting was measured at an angular frequency of 0.1 rad / sec. The complex viscosity “η ^* _0.1 ” and the melt complex viscosity “η ^* ₁₀₀ ” measured at an angular frequency of 100 rad / sec were determined.
<Measurement conditions>
Geometry: Parallel plate Plate diameter: 25mm
Plate spacing: 1.5-2mm
Strain: 5%
Angular frequency: _{0.1 to 100} rad / sec Measurement atmosphere: Nitrogen η ^* _0.1 / η ^* ₁₀₀ was calculated from η * measured by the method described above.

(5) Adhesive strength (unit: N / 25mm width)
In order to evaluate adhesiveness, adhesive strength evaluation was performed according to the following procedures. This evaluation method is based on JIS Z0237-2000 “Adhesive tape / adhesive sheet test method”. As the adherend, ZEONOR film 1020R (thickness 100 μm) manufactured by Nippon Zeon Co., Ltd., which is used as an optical film, was used.
1) Three samples of a sample film cut to a width of 25 mm are prepared for each sample.
2) The ZEONOR film, which is an adherend, is attached on an acrylic plate (50 mm × 150 mm × thickness 3 mm) using a double-sided tape.
3) The sample film was bonded so that the surface in contact with the cooling roll during manufacture was in contact with the ZEONOR film. The pasting was performed by using an automatic crimping apparatus described in JIS Z0237, with a crimping speed of 5 mm / sec and a round trip of one crimping.
4) The sample prepared in 3) (hereinafter abbreviated as a measurement sample) was subjected to an aging treatment for 1 hour in a three-level temperature environment of 23 ° C., 40 ° C., and 60 ° C.
5) The measurement sample was allowed to stand for 30 minutes in an atmosphere of a predetermined temperature (23 ° C., 40 ° C. or 60 ° C.) and a relative humidity of 65% RH.
6) The sample for measurement was measured using an autostrain type tensile tester manufactured by Toyo Seiki Seisakusho Co., Ltd. at a peeling angle of 180 ° and a tensile speed of 300 mm / min.

(6) Internal HAZE (Unit:%)
Internal HAZE, which is a measure of transparency, was measured using a digital haze meter (manufactured by Suga Test Instruments). The internal HAZE was calculated by filling a quartz cell with a dimethyl phthalate solution, immersing a sample film therein, and measuring the HAZE of the entire cell. It shows that transparency at the time of adherend bonding is excellent, so that this value is small.

(7) Diffuse transmitted light intensity (LSI) (Unit:%)
The measurement was made with an LSI tester manufactured by Toyo Seiki Co., Ltd. (scattered transmitted light of ± 0.4 ° to 1.2 ° was received). It shows that flicker is suppressed, so that this value is small.

Example 1
An ethylene-α-olefin copolymer [Sumitomo Chemical Co., Ltd. Sumikasen EP GT140 (MFR = 0.9 g / 10 min, density = 918 kg / m ³ )] was melt-kneaded with a φ65 mm extruder and extruded from a T die, The polyethylene melt film immediately after extrusion is pressure-bonded at a pressing roll linear pressure of 19.6 kN / m with a metal cooling roll having an arithmetic average roughness (Ra) of 0.1 μm and a pressing roll made of silicon rubber (hardness: 80). A polyethylene film was obtained.
The polyethylene melt film temperature immediately after being extruded from the T die was 330 ° C., the film width was 400 mm, the film thickness was 40 μm, and the take-up speed was 54 m / min. Table 1 shows the physical property evaluation results of the obtained polyethylene film.

Comparative Example 1
An ethylene-α-olefin copolymer [Sumikasen E FV403 (MFR = 3.7 g / 10 min, density = 918 kg / m ³ ) manufactured by Sumitomo Chemical Co., Ltd.] was melt-kneaded with a φ65 mm extruder and extruded from a T die. The polyethylene melt film immediately after extrusion is pressure-bonded at a pressing roll linear pressure of 19.6 kN / m with a metal cooling roll having an arithmetic average roughness (Rz) of 0.1 μm and a pressing roll made of silicon rubber (hardness: 80). A polyethylene film was obtained.
The polyethylene melt film temperature immediately after being extruded from the T die was 250 ° C., the film width was 400 mm, the film thickness was 30 μm, and the take-up speed was 50 m / min. Table 1 shows the physical property evaluation results of the obtained polyethylene film.

Comparative Example 2
An ethylene-α-olefin copolymer [Sumikasen Hiα FW401-0 (MFR = 5.1 g / 10 min, density = 923 kg / m ³ ) manufactured by Sumitomo Chemical Co., Ltd.] was melted and kneaded with a φ65 mm extruder and from a T die. The polyethylene melt film immediately after extrusion and extrusion is pressed with a metal cooling roll having an arithmetic average roughness of 0.1 μm and a pressing roll made of silicon rubber (hardness: 80) at a pressing roll linear pressure of 19.6 kN / m. A film was obtained.
The polyethylene melt film temperature immediately after being extruded from the T die was 230 ° C., the film width was 400 mm, the film thickness was 30 μm, and the take-up speed was 50 m / min. Table 1 shows the physical property evaluation results of the obtained polyethylene film.

Comparative Example 3
High-pressure low-density polyethylene resin [Sumikasen CE4506 (MFR = 7.1 g / 10 min, density = 918 kg / m ³ ) manufactured by Sumitomo Chemical Co., Ltd.] was melt-kneaded with a φ65 mm extruder, extruded from a T die, and immediately after extrusion. The polyethylene melt film was pressure-bonded with a metal cooling roll having an arithmetic average roughness of 0.1 μm and a pressing roll made of silicon rubber (hardness: 80) at a pressing roll linear pressure of 19.6 kN / m to obtain a polyethylene film.
The polyethylene melt film temperature immediately after being extruded from the T die was 230 ° C., the film width was 400 mm, the film thickness was 30 μm, and the take-up speed was 50 m / min. Table 1 shows the physical property evaluation results of the obtained polyethylene film.

Claims (3)

A polyethylene melt film obtained by melting and kneading an ethylene-α-olefin copolymer satisfying the following requirements (A) and (B) with an extruder and extruding from a T die,
A method for producing a polyethylene film, comprising pressing between a cooling roll having a surface arithmetic average roughness (Ra) of 0.5 μm or less and a pressing roll having at least a surface made of rubber.
(A) Flow activation energy (Ea) is 40 to 100 kJ / mol
(B) Ratio of melt complex viscosity η * _0.1 measured at an angular frequency of _0.1 rad / sec and melt complex viscosity η * ₁₀₀ measured at an angular frequency of 100 rad / sec at 190 ° C. Η ^* _0.1 / η ^* ₁₀₀ is 10 to 100 The method for producing a polyethylene film according to claim 1, wherein the temperature of the polyethylene molten film extruded from the T-die is 270 ° C or higher. The method for producing a polyethylene film according to claim 1 or 2, wherein the linear pressure of the pressing roll when the polyethylene molten film is clamped by the cooling roll and the pressing roll is 15 to 35 kN / m.