JP2010013498A - Film to be attached to package window - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film that is enhanced in high-speed cutting properties and adhesion between paper and the film when a package is manufactured. <P>SOLUTION: The film to be attached to a package window comprises a polylactic acid film mainly composed of a polylactic acid resin and, formed at least on one surface thereof, an antistatic agent layer having a surface specific resistivity of at most 10<SP>11</SP>Ω/SQUARE and has a wet tension of 37-45 mN/m for the surface brought into contact with a base material of the package. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biodegradable film mainly composed of a polylactic acid-based resin, and more specifically, a window pasting such as a package (envelope) for packing stationery, a package for packing towels and clothes, a package for packing toys, and the like. The present invention relates to a film suitable for use.

  In recent years, with the increasing awareness of the environment, activities to reduce carbon dioxide emissions, which cause global warming, are being addressed in various fields. In particular, plastic products using petroleum as a raw material have a problem that a large amount of carbon dioxide gas is generated during disposal.

  Amid these growing environmental problems, biodegradable plastics using various plant-derived raw materials that decompose in the natural environment after disposal in order to reduce environmental burden and make society sustainable Is now required.

Among these biodegradable plastics, polylactic acid resins are superior in transparency, rigidity, and processability compared to other biodegradable plastics, especially because the film is stiff and excellent in transparency. Suitable for various packaging films, bags, window pasting films for containers with windows, envelope window pasting films, and cellophane replacement films.

  However, the polylactic acid-based resin is a brittle resin in an unstretched state, and for improvement, as disclosed in Patent Document 1 and Patent Document 2, biaxial stretching is used to increase mechanical strength. Thus, it is used as a film with dimensional stability. Further, as in Patent Document 4, a film by an inflation method is used because it is economically advantageous.

Turning to the use of these films, the processing speed is increasing due to advances in processing machines. Especially for envelope window pasting applications, there are advances in bag making machines, and if you use a rotary bag making machine,
Various long and square envelopes can be pasted on windows at high speed and with high accuracy using roll film and roll paper. However, when speeding up progresses, the cut property of the film which can endure high speed is requested | required. Further, the adhesiveness between the paper and the film used for the envelope at the time of creating the envelope has emerged as a problem at the time of speed up.
JP-A-7-207041 JP-A-7-256653 JP-A-6-23836 JP-A-2005-002243

  The present invention is a package window pasting film having at least a polylactic acid-based film and an antistatic agent layer, wherein the package window pasting film has improved high-speed cutability during envelope creation and adhesion between paper and film. It is to be provided.

  The present invention has reached the present invention as a result of intensive studies in order to solve the above problems.

That is, the present invention is any of the following.
1) An antistatic agent layer having a surface specific resistance value of 10 ¹¹ Ω / □ or less is provided on at least one surface of a polylactic acid film mainly composed of a polylactic acid resin;
A film for pasting a package window, wherein the wetting tension of the surface in contact with the package substrate is 37 to 45 mN / m.
2) The film for pasting a package window as described in 1) above, wherein the polylactic acid film is a polylactic acid film formed by an inflation method.
3) The package window pasting film according to 1) or 2), wherein the haze is more than 2% and 10% or less.
4) The package window pasting film according to any one of 1) to 3), wherein an average surface roughness SRa measured by a three-dimensional surface roughness measuring instrument is 0.02 to 0.12 μm on both surfaces of the film.
5) The film for pasting a package window according to any one of 1) to 4) above, wherein the polylactic acid film contains inorganic particles having a particle size of 30 μm or less.
6) The package window pasting film according to any one of 1) to 5) above, wherein the package is an envelope.

  Since the present invention is a film for pasting a package window in which at least one surface of a polylactic acid film is provided with antistatic properties and easy adhesion to the surface in contact with the envelope substrate, the film is peeled off when the processing speed is increased. Charging is unlikely to occur, so that the film can be supplied smoothly, the contact angle of the cutting blade is stabilized during cutting, and the cutting property is improved.

  In addition, because the adhesive surface of the package base material has easy adhesion, the adhesion between the paper and film of the package base material is improved, and when the film of the present invention is used for pasting an envelope window, the speed can be increased. Can withstand.

The present invention has an antistatic agent layer having a surface resistivity of 10 ¹¹ Ω / □ or less on at least one surface of a polylactic acid-based film, and a wetting tension on the surface in contact with the package substrate is 37 to 45 mN / m. This is a film for pasting a package window. The present invention will be specifically described below.

  The package window pasting film of the present invention has at least a polylactic acid film and an antistatic agent layer. The polylactic acid film constituting the package window pasting film is mainly composed of (all components of the polylactic acid film). 50% by weight or more with respect to 100% by weight). The polylactic acid film is preferably 60% by weight, more preferably 70% by weight, based on 100% by weight of all components of the polylactic acid film.

  The weight average molecular weight of the polylactic acid resin used in the present invention is preferably 50,000 to 500,000, more preferably 100,000 to 25, in order to satisfy appropriate film formation, stretchability and practical mechanical properties. Ten thousand. In addition, a weight average molecular weight here means the molecular weight which measured with the chloroform solvent by the gel permeation chromatography, and was calculated by the polymethylmethacrylate conversion method.

  The polylactic acid resin used in the present invention is a polymer mainly composed of a structure that can be obtained using L-lactic acid and / or D-lactic acid as a raw material, but includes other copolymerization components other than lactic acid. You may go out.

  Such other monomers include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, Glycol compounds such as pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalate Acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarbohydrate Acids, dicarboxylic acids such as 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid and other hydroxycarboxylic acids, caprolactone, Examples include lactones such as valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one. The copolymerization amount of the other copolymerization component in the polylactic acid resin is preferably 0 to 30% by weight with respect to 100% by weight of all monomer components of the polylactic acid resin.

  The polylactic acid film used for the film for pasting a package window of the present invention is preferably a polylactic acid film formed by an inflation method. Specifically, the raw material resin is supplied to a single-screw or twin-screw extruder, melted and mixed, and directly inflated into a bubble shape by the air filled with the molten resin extruded into a tube shape from a cylindrical die, and air-cooled or water-cooled. It is a method of picking up with a pinch roll. A film formed by the inflation method is preferable because the orientation is uniform in each direction, and the film cut surface is clean and the speed can be increased when a window-sealed envelope is made by a rotary bag making machine. When a polylactic acid film used for a package window packaging film is formed by a method other than the inflation method, there may be problems such as insufficient strength of the film and an increase in equipment costs. It is preferable to form a film by the method.

  Although the thickness of a polylactic acid-type film is not specifically limited, It is the range of 5-100 micrometers, More preferably, it is the range of 10-40 micrometers.

  It is important that the package window pasting film of the present invention has an antistatic agent layer having a specific surface specific resistance value on at least one surface of the polylactic acid film.

The antistatic agent layer can be applied by coating a polylactic acid film with a commercially available surfactant, ammonium salt or the like in-line or off-line. It is important that the surface specific resistance value of the antistatic agent layer is 10 ¹¹ Ω / □ or less. If the surface resistivity exceeds 10 ¹¹ Ω / □, the film will meander when applied to a rotary bag making machine, resulting in poor cutability. More preferably, it is 10 ¹⁰ Ω / □ or less, and further preferably 10 ⁹ Ω / □ or less. Further, the lower the surface specific resistance value, the better. However, since it is difficult to set it to 10 ⁶ or less with the current practical technology, the realistic lower limit value is considered to be 10 ⁶ Ω / □.

  In the film for pasting a package window of the present invention, it is important that the wetting tension on the surface in contact with the package substrate is a specific value.

  A specific wetting tension can be applied to the film for pasting a package window in-line or off-line by corona treatment, plasma treatment or coating treatment. In the package window pasting film of the present invention, it is important that the wetting tension of the surface in contact with the package substrate is in the range of 37 to 45 mN / m. If it is smaller than this range, when the package is made at high speed, the adhesion between the paper as the package base material and the film for pasting a package window of the present invention is poor, and the film is peeled off from the paper as the base material. The creation speed cannot be increased. On the other hand, if it is larger than this range, the glue part is too wide and protrudes. More preferably, it is 38-44, More preferably, it is 39-44.

  In the film for pasting a package window of the present invention, the wetting tension on the other surface is not particularly limited as long as the wetting tension on the surface in contact with the package substrate is 37 to 45 mN / m. When the film for pasting a package window of the present invention has a structure having an antistatic agent layer on both sides of a polylactic acid-based film, it is sufficient that the wet tension of one antistatic agent layer is a value of 37 to 45 mN / m, When the film for pasting a package window of the present invention has an antistatic agent layer on one side of the polylactic acid-based film, even if the wetting tension on the antistatic agent layer side is a value of 37 to 45 mN / m, the polylactic acid-based film There is no particular problem even if the film side tension is 37 to 45 mN / m, but preferably the film tension on the side opposite the antistatic layer on the polylactic acid film side is 37 to 45 mN / m. It is.

  Examples of the method for setting the wetting tension in the range of 37 to 45 mN / m include corona treatment, plasma treatment, and coating treatment as described above, and a method of coating a polyester resin is preferable. More preferable polyester resins include water-soluble polyester resins.

  The haze of the film for pasting a package window of the present invention is preferably more than 2% and 10% or less. If it is smaller than this range, the film is easily scratched and the appearance is deteriorated when it is made into a windowed package, and if it is larger than this range, characters and designs in the package cannot be read, which is not preferable for practical use. A more preferable haze value is more than 5% and 9% or less.

  Moreover, in order to implement | achieve speeding-up of the rotary bag making machine of the film for package window sticking of this invention, it is preferable that the average surface roughness SRa of the film for package window paste is 0.02-0.12 micrometer. If the thickness is smaller than this range, the film is likely to wrinkle or meander. If it is larger than this range, the film is liable to cause winding misalignment, which may hinder envelope production. More preferably, it is 0.03-0.09 micrometer.

  When adjusting the average surface roughness SRa of the package window pasting film, it is important to control the average surface roughness SRa on both sides. That is, when the film for pasting a package window of the present invention has antistatic agent layers on both sides of a polylactic acid film, the average surface roughness SRa of the antistatic agent layers on both sides is 0.02 to 0.12 μm. Well, when the film for pasting a package window of the present invention has an antistatic agent layer on one side of a polylactic acid film, the average surface roughness SRa on both sides of the antistatic agent layer side and the polylactic acid film side is 0. It is preferable that it is 02-0.12 micrometer.

  It is preferable that the film for pasting a package window of the present invention imparts slipperiness in order to increase the speed of the rotary bag making machine. In order to impart smoothness, for example, in a package window pasting film having an antistatic layer only on one side, the polylactic acid film has inorganic particles such as calcium carbonate, silica, barium sulfate, kaolin, etc. having a particle size of 30 μm or less. It is preferable to contain. The particle size is more preferably 20 μm or less. When the particle size exceeds 30 μm, the haze of the polylactic acid film is increased, and as a result, the haze of the package window pasting film is increased, or the package window pasting film is liable to be wound.

  The polylactic acid-based film having an antistatic agent layer on at least one surface of the present invention is provided for attaching a package window.

  Moreover, it does not specifically limit as a package in which the film for package window sticking of this invention is used, It can use for various packages of the use which can observe an inside by providing a window part with a film. Examples of such a package include a package (envelope) for packing stationery, a package for packing towels and clothes, a package for packing toys, and the like. Used for pasting. The package window pasting film of the present invention is preferably used for envelopes. By using the package window pasting film of the present invention for envelope window pasting applications, it is excellent in high-speed cutability, high-speed envelope window pasting suitability, and more preferable because the adhesiveness to the envelope paper as a package base material is good. If it is the film for package window sticking of this aspect of this invention, since an internal character is also easy to read, it can be used suitably.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.

[Measurement and evaluation method]
Measurements and evaluations shown in the examples were performed under the following conditions.
(1) Surface Specific Resistance Value After being left for 1 day in an environment of a temperature of 23 ° C. and a relative humidity of 50%, the antistatic agent layer side was measured according to JIS-K6911 under the same conditions.
(2) Nure Tension Using the ethylene glycol monoethyl ether, formamide, and a mixture thereof as the Nule prescribed solution, the side in contact with the package substrate was measured according to JIS-K-6768.
(3) Haze It measured from the antistatic agent layer side according to JIS-K7105.
(4) Average surface roughness (SRa)
Using a stylus type three-dimensional roughness meter ET4000AK manufactured by Kosaka Laboratory, both surfaces were measured under the following conditions.

Measuring force: 100 N, X pitch: 1.00 μm, Y pitch: 5 μm, Z measuring magnification: 20000
X feed speed: 0.1 mm / sec, low cut: 0.25 mm, high cut: R + W
Leveling: Untreated (5) Particle size The sample is prepared by ion-sputtering Pt-Pd on the surface of the package window pasting film, and the surface of the package window pasting film is observed using a scanning electron microscope S-800 manufactured by Hitachi, Ltd. I took a photo. The particle size was measured from the photograph.
(6) High-speed cutability Film when a roll-shaped package window pasting film is run on a bag making machine at a speed of 40 m / min, and the film is cut at a high speed to the size of an envelope window (105 x 60 mm) When the cut surface was observed, the case where it was cut cleanly was marked as ◯, the case where whiskers or uneven cutting remained at the cut edge, and Δ when the cut edge was dirty and could not be used.
(7) Suitability for high-speed envelope window sticking Film rolls are pre-determined on a 45 x 90 mm window frame in a 120 x 235 mm envelope (made of paper) using a Fuji bag making machine (FRE / NRNH series). Gluing was carried out while cutting into the size of, and the adhesive strength between the glue and the film was confirmed by changing the speed.
○: A film that can be pasted and pasted at over 450 sheets / minute.
Δ: A film that can be pasted at 350 to 449 sheets / minute and can be pasted on a window.
X: Film that can be pasted at 349 sheets / minute or less and can be pasted on a window
(Examples 1 and 2)
It was melt-extruded at 220 ° C. using a polylactic acid resin containing 0.5% by weight of calcium carbonate having a particle size of 20 μm. Using a ring die, a film was formed by an inflation method (blow ratio 2.5) to prepare 2500 m of a polylactic acid film roll 2500 m in thickness. On one side of this polylactic acid film roll, staticide (antistatic agent, Mitsui Bussan Plastics Co., Ltd. sales) is applied at a thickness of 20 mg / m ² , and a plus coat is applied on the surface in contact with the envelope substrate on the opposite side ( In Example 1, a water-soluble polyester resin manufactured by Kako Chemical Co., Ltd. was applied as an easy-adhesion layer at a thickness of 10 mg / m ^{2 in} Example 1, and at a thickness of 20 mg / m ^{2 in} Example 2. The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1.
(Examples 3 and 4)
A polylactic acid film roll 2500 m was prepared in the same manner as in Examples 1 and 2.

In Example 3, 10 mg / m ² was applied to the surface of the polylactic acid film roll having a thickness of 10 mg / m ² , and a positive coat was applied to the surface in contact with the envelope substrate on the opposite side. was applied in a thickness, it was coated in a thickness of example 4, 20 mg / ^{m 2.} The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1. The easy adhesion layer side was the side in contact with the envelope substrate.
(Example 5)
Melt extrusion was performed at 220 ° C. using a polylactic acid resin containing 1.0% by weight of calcium carbonate having a particle size of 20 μm. Using a ring die, a film was formed by an inflation method (blow ratio 2.5) to prepare 2500 m of a polylactic acid film roll 2500 m in thickness. The static side was applied to one side of the film roll at a thickness of 20 mg / m ² , and the plus coat was applied to the surface in contact with the envelope substrate on the opposite side at a thickness of 10 mg / m ² . The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1.

Since Example 5 has a slightly larger haze than Examples 1 to 4 and the like, when the characters in the envelope are read from the envelope window using the envelope window pasting film of the present invention, the characters are slightly read. It became difficult.
(Example 6)
Melt extrusion was performed at 220 ° C. using a polylactic acid resin containing calcium carbonate having a particle size of 30 μm of 0.3% by weight and a particle size of 10 μm of 0.3% by weight. Using a ring die, a film was formed by an inflation method (blow ratio 2.5) to prepare 2500 m of a polylactic acid film roll 2500 m in thickness. The static side was applied to one side of the film roll at a thickness of 20 mg / m ² , and the plus coat was applied to the surface in contact with the envelope substrate on the opposite side at a thickness of 10 mg / m ² . The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1.

  In Example 6, since the average surface roughness SRa was somewhat larger than in Examples 1 to 4, etc., the suitability for pasting high-speed envelope windows was somewhat inferior.

(Comparative Examples 1, 2, 3)
Melt extrusion was performed at 220 ° C. using a polylactic acid resin containing 0.5% by weight of calcium carbonate having a particle size of 20 μm. Using a ring die, a film was formed by an inflation method (blow ratio 2.5) to prepare 2500 m of a polylactic acid film roll 2500 m in thickness.

In Comparative Example 1, the static side was applied to one side of the film roll with a thickness of 20 mg / m ² , and the surface in contact with the envelope substrate on the opposite side was not treated.

In Comparative Example 2, no treatment was performed on one side, and a plus coat was applied as an easy-adhesive layer to the surface in contact with the envelope base material with a thickness of 20 mg / m ² . In Comparative Example 3, no treatment was performed on one side, and a plus coat was applied as an easy-adhesion layer to the surface in contact with the envelope base material at a thickness of 100 mg / m ² .

The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1.
(Comparative Example 4)
It melt-extruded at 220 ° C. using a polylactic acid resin containing 0.05% by weight of calcium carbonate having a particle size of 20 μm. Using a ring die, a film was formed by an inflation method (blow ratio 2.5) to prepare 2500 m of a polylactic acid film roll 2500 m in thickness. The static side was applied to one side of this film roll at a thickness of 20 mg / m ² , and the surface in contact with the envelope substrate on the opposite side was not treated. The film roll was run on a rotary bag making machine to make an envelope. The results are shown in Table 1.

Claims (6)

Having an antistatic agent layer having a surface resistivity of 10 ¹¹ Ω / □ or less on at least one surface of a polylactic acid film mainly composed of a polylactic acid resin;
A film for pasting a package window, wherein the wetting tension of the surface in contact with the package substrate is 37 to 45 mN / m.   2. The package window pasting film according to claim 1, wherein the polylactic acid film is a polylactic acid film formed by an inflation method.   The package window pasting film according to claim 1 or 2, wherein the haze exceeds 2% and is 10% or less.   The package window pasting film according to any one of claims 1 to 3, wherein an average surface roughness SRa measured by a three-dimensional surface roughness measuring instrument is 0.02 to 0.12 µm on both sides of the film.   The film for pasting a package window according to any one of claims 1 to 4, wherein the polylactic acid-based film contains inorganic particles having a particle size of 30 µm or less.   The package window pasting film according to claim 1, wherein the package is an envelope.