JP2008184478A - Antistatic polypropylene film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a biaxially oriented polypropylene film having an excellent printability with a water-based ink and an excellent antistatic property. <P>SOLUTION: The antistatic polypropylene film comprises 100 parts by mass of a polypropylene film and 0.1-2.0 parts by mass of an antistatic agent which is a mixture of a compound A group: a specific glycerin fatty acid monoester, a compound B group: a specific diglycerin fatty acid partial ester, a compound C group: a specific sorbitan fatty acid partial ester and a compound D group: a specific amine ester compound and has a solubility parameter (SP value) of 11.1-12.0. The mixture of the compounds A-D groups is the mixture of a mixture (mixture of the compound A-C groups) selected from each of two or three compound groups of the compound A-C groups and a compound D selected from the compound D group and the mass ratio of the mixture of the compound A-C groups to the compound D is (the mixture of the compound A-C groups)/the compound D=40/60-80/20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antistatic polypropylene film, and more particularly to a polypropylene film having excellent antistatic properties and excellent adhesion and transferability with water-based inks.

  Polypropylene film has no polar groups in its structure, so it is easy to charge, and when used as it is for packaging film, it tends to cause dust adhesion and blocking between films, so antistatic agents are used almost without exception. Has been. If the antistatic agent is not bleed on the film surface, the effect will not be obtained, and since the bleed antistatic agent exists between the printing ink and the film, it causes the printability to deteriorate and the film is transparent due to excessive bleed. This causes the quality of the product to be impaired. In particular, when printing is performed with water-based ink, the printability is hindered by the antistatic agent, causing ink bleeding and poor adhesion.

Polyoxyethylene alkylamides, polyhydric alcohol fatty acid partial esters, polyoxyethylene alkylamines, alkenyl diethanolamides and higher fatty acid esters, alkyl diethanolamines and higher fatty acids as antistatic agents for polypropylene films that do not impair the adhesion of aqueous inks However, it is not yet satisfactory in terms of printability such as ink bleeding and ink transfer.
JP-A-7-164608 JP 2002-210901 A JP 2003-268166 A JP 2005-187633 A

  An object of the present invention is to provide a polypropylene film having good antistatic properties and good printability for water-based inks.

  As a result of intensive studies to solve the above problems, the present inventors have found a specific antistatic agent having a solubility parameter (hereinafter sometimes abbreviated as SP value) of 11.1 to 12.0. It has been found that the above problems can be solved by adding 0.1 to 2.0 parts by mass in a polypropylene film, and the present invention has been completed.

That is, this invention which solves the said subject has the following structure.
1. 100 parts by mass of polypropylene film contains 0.1 to 2.0 parts by mass of an antistatic agent having a solubility parameter (SP value) of 11.1 to 12.0, which is a mixture of the following A to D compound groups. And
The mixture of the A to D compound groups is a mixture (A to C compound group mixture) selected from each of two or three compound groups of the following A to C compound groups, and D selected from the following D compound groups Charging characterized in that the mass ratio of the A to C compound group mixture and the D compound is (A to C compound group mixture) / D compound = 40/60 to 80/20. Prevention polypropylene film.

Compound A group:
Glycerin fatty acid monoester which is an ester of glycerin and a fatty acid having 12 to 18 carbon atoms and has an SP value in the range of 10.5 to 11.5

B compound group:
Diglycerin fatty acid partial ester which is an ester of diglycerin and a fatty acid having 12 to 18 carbon atoms and has an SP value in the range of 11.0 to 12.5

C compound group:
Sorbitan fatty acid partial ester which is an ester of sorbitan and a fatty acid having 12 to 18 carbon atoms and having a SP value in the range of 9.0 to 13.0

D compound group:
Polyoxyethylene alkylamine or polyoxyethylene alkenylamine obtained by adding 2 to 3 moles of ethylene oxide to 1 mole of alkylamine or alkenylamine having 12 to 18 carbon atoms and fatty acid having 12 to 18 carbon atoms An amine ester compound having an SP value in the range of 9.0 to 10.0.

2. 2. The antistatic polypropylene film as described in 1 above, wherein the polypropylene film is obtained by a biaxial stretching method, and is printed with water-based ink on at least one side.

  By using the antistatic agent of the present invention, it is possible to obtain a biaxially stretched polypropylene film excellent in printability with aqueous ink.

Hereinafter, the components of the antistatic agent of the present invention will be described.
The A compound group of the present invention is obtained by an esterification reaction between glycerin and a fatty acid having 12 to 18 carbon atoms, or an ester exchange reaction of a glycerin fatty acid triester having 12 to 18 carbon atoms of glycerin and constituent fatty acids. In view of the antistatic effect, the monoester content is preferably 95% by mass or more. A glycerin fatty acid ester having a monoester content of 95% by mass or more can be obtained by a method such as molecular distillation or chromatographic fractionation of the reaction product obtained by the esterification reaction or transesterification.

Examples of the fatty acid having 12 to 18 carbon atoms include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and isostearic acid. Such glycerin fatty acid esters include glycerin monolaurate (SP value: 11.46), glycerin monomyristate (SP value: 11.18), glycerin monopalmitate (SP value: 10.95), glycerin monostearate. (SP value: 10.76), glycerol monooleate (SP value: 10.64), glycerol monoisostearate (SP value: 10.76), and the like. Fatty acids having a carbon number of less than 12 have a problem of volatilization during processing, and if it exceeds 18, a problem of bleed whitening of the film occurs, which is not preferable.
These can be used alone or in a mixture.

The B compound group of the present invention can be obtained by esterifying diglycerin and a fatty acid having 12 to 18 carbon atoms, and using a purification method such as molecular distillation or chromatography.
Examples of the fatty acid having 12 to 18 carbon atoms include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and isostearic acid.

Such diglycerin fatty acid esters include diglycerin monolaurate (SP value: 12.17), diglycerin monomyristate (SP value: 11.88), diglycerin monopalmitate (SP value: 11.63), Examples include glycerin monostearate (SP value: 11.42), diglycerin monooleate (SP value: 11.32), and diglycerin monoisostearate (SP value: 11.37).
Fatty acids having a carbon number of less than 12 have a problem of volatilization during processing, and if it exceeds 18, a problem of bleed whitening of the film occurs, which is not preferable.
These can be used alone or in a mixture.

  The C compound group of the present invention can be obtained by esterifying sorbitan and a fatty acid having 12 to 18 carbon atoms and using a purification method such as chromatography. Examples of the fatty acid having 12 to 18 carbon atoms include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and isostearic acid. Such sorbitan fatty acid esters include sorbitan monolaurate (SP value: 12.81), sorbitan monomyristate (SP value: 12.43), sorbitan monopalmitate (SP value: 12.12), sorbitan monostearate ( SP value: 11.85), sorbitan monooleate (SP value: 11.76), sorbitan monoisostearate (SP value: 11.80), sorbitan dilaurate (SP value: 10.75), sorbitan dimyristate ( SP value: 10.51), sorbitan dipalmitate (SP value: 10.32), sorbitan distearate (SP value: 10.17), sorbitan dioleate (SP value: 10.03), sorbitan diisostearate Rate (SP value: 10.10), Sorbitan trilaurate (SP value: 9.80) Sorbitan trimyristate (SP value: 9.65), sorbitan tripalmitate (SP value: 9.54), sorbitan tristearate (SP value: 9.45), sorbitan trioleate (SP value: 9.28) And sorbitan triisostearate (SP value: 9.37).

Fatty acids having a carbon number of less than 12 have a problem of volatilization during processing, and if it exceeds 18, a problem of bleed whitening of the film occurs, which is not preferable.
These can be used alone or in a mixture.

  The D compound group of the present invention is a polyoxyethylene alkylamine or polyoxyethylene alkenylamine 1 that can be obtained by adding 2 to 3 mol of ethylene oxide to 1 mol of an alkylamine or alkenylamine having 12 to 18 carbon atoms. It is an amine ester compound that can be obtained by an esterification reaction between 1 mol of a mole and 1 mol of a fatty acid (12 to 18 carbon atoms). At this time, the content of the amine ester compound is desirably 50% or more by GPC analysis.

  Such amine ester compounds include lauryl diethanolamine monolaurate (SP value: 9.56), lauryl diethanolamine monomyristate (SP value: 9.51), lauryl diethanolamine monopalmitate (SP value: 9.46), lauryl diethanolamine. Monostearate (SP value: 9.41), lauryl diethanolamine monooleate (SP value: 9.32), myristyl diethanolamine monolaurate (SP value: 9.51), myristyl diethanolamine monomyristate (SP value: 9. 46), myristyl diethanolamine monopalmitate (SP value: 9.41), myristyl diethanolamine monostearate (SP value: 9.37), myristyl diethanolamine monooleate (SP value: 9.2) ), Palmityl diethanolamine monolaurate (SP value: 9.46), palmityl diethanolamine monomyristate (SP value: 9.41), palmityl diethanolamine monopalmitate (SP value: 9.37), palmityl diethanolamine Monostearate (SP value: 9.33), palmityl diethanolamine monooleate (SP value: 9.25), stearyl diethanolamine monolaurate (SP value: 9.41), stearyl diethanolamine monomyristate (SP value: 9) .37), stearyl diethanolamine monopalmitate (SP value: 9.33), stearyl diethanolamine monostearate (SP value: 9.30), stearyl diethanolamine monooleate (SP value: 9.22), oleyldie Nolamine monolaurate (SP value: 9.32), oleyl diethanolamine monomyristate (SP value: 9.28), oleyl diethanolamine monopalmitate (SP value: 9.25), oleyl diethanolamine monostearate (SP value) : 9.22), oleyl diethanolamine monooleate (SP value: 9.15), and the like.

  When the carbon number of the alkyl group or alkenyl group of the amine ester compound is less than 12, the film is likely to be blocked, resulting in a problem of volatility during processing. Moreover, when carbon number of an alkyl group or an alkenyl group exceeds 18, whitening of a film will become a problem.

When the added mole number of polyoxyethylene is less than 2, the antistatic effect is lowered, and when it exceeds 3, the film is easily blocked.
These can be used alone or in a mixture.

  The printability of the water-based ink is caused by the compatibility between the binder resin in the ink and the biaxially stretched polypropylene film, and further depends on the compatibility between the antistatic agent and the binder resin when the antistatic agent is used. Accordingly, an antistatic agent having an SP value of a mixture of A to D compound groups of 11.1 to 12.0, wherein the mixture of the A to D compound groups is a mixture of the A to C compound groups, and D It is a mixture with a D compound selected from the compound group, and the mass ratio of the A to C compound group mixture and the D compound is (A to C compound group mixture) / D compound = 40/60 to 80/20 The use of a certain antistatic agent does not inhibit the compatibility with the binder resin, and further has an appropriate bleed from the difference in SP value from the biaxially stretched polypropylene resin, so that a high antistatic effect is obtained.

Regarding the present invention, even if the mixture of the A to D compound group is constituted by the mixture of the compound selected from one compound group of the A to C compound group and the D compound, the effect of the present invention is not obtained.
When the surfactant of the present invention is selected from two or three compound groups of the A to C compound groups, the surfactant of the selected compound group is 10% by mass or more for each compound group Is preferred.

The solubility parameter was calculated according to the method of FEDORS (R. FEDORS, POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol 14, No. 2).
FEDORS et al. Consider that the solubility parameter (σ) depends on both the cohesive energy density (Ecoh) and molar molecular volume (V) depending on the type and number of substituents and is shown in the following formula and Table 1. Use constants.

  When the solubility parameter is calculated using the above formula and constant, glycerin monostearate: 10.76, diglycerin monolaurate: 12.17, sorbitan monostearate: 11.85, stearyl diethanolamine monostearate: 9. 52. Glycerol monostearate and stearyl diethanolamine monostearate have a high antistatic effect, but have a low SP value, and therefore tend to have poor printability with aqueous ink. Therefore, the above-mentioned problems can be improved by using a polyhydric alcohol monocarboxylic acid ester having a high SP value such as diglycerin monolaurate or sorbitan stearate in combination.

  If one or more surfactants selected from the D compound group of the present invention exceeds 60% by mass, the solubility parameter becomes 11.1 or less, and printability is inhibited. The effect drops and is not preferable. Therefore, (a mixture selected from each of two or three compound groups selected from the A, B, and C compound groups) / D compound = 40/60 to 80/20 in the ratio of printability. And high antistatic performance is preferable.

  The addition amount with respect to a biaxially stretched polypropylene film is 0.1-2.0 mass parts with respect to 100 mass parts of resin. More preferably, it is 0.5-1.5 mass parts. When the addition amount is less than 0.1 parts by mass, the antistatic effect is weak, and when it exceeds 2.0 parts by mass, bleed whitening is observed and transparency is inhibited.

  Various additives such as antioxidants, lubricants, colorants, UV absorbers, fillers, antiblocking agents, surfactants outside the present invention are added to the biaxially stretched polypropylene film of the present invention as necessary. can do. As these additives, known ones can be used without any particular limitation.

The propylene polymer constituting the biaxially stretched polypropylene film of the present invention has a normal density of 0.890 to 0.930 g / cm ³ and an MFR of 0.5 to 60 g / 10 min. A random or block copolymer with a small amount (5 mol% or less) of an α-olefin.

  The biaxially stretched polypropylene film of the present invention may be a single layer film or a multilayer film in which two or more kinds of resins are laminated.

  In the biaxially stretched polypropylene film of the present invention, at least one surface of the film is printed with water-based ink. Printing on the surface of the biaxially stretched polypropylene film can be performed by screen printing, flexographic printing, gravure printing or the like that is usually used. When printing on a biaxially stretched polypropylene film, ink adhesion can be improved by subjecting the film surface to surface activation treatment such as corona surface treatment or frame surface treatment prior to printing. For this reason, it is desirable to activate the film surface by corona surface treatment or the like.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
1. Antistatic agent A component: Glycerin monostearate (Riken Vitamin Rikemar S-100A was used. The SP value was calculated from the gas chromatographic composition and was 10.82.)
Component B: Diglycerin monolaurate (Poem DL-100 manufactured by Riken Vitamin Co., Ltd. was used. When the SP value was calculated from the gas chromatographic composition, it was 12.79)
C component: Sorbitan monostearate (Rikenmar S-300W manufactured by Riken Vitamin Co., Ltd. was used. When the SP value was calculated from the gas chromatographic composition, it was 11.79.)
D component: Stearyl diethanolamine monostearate (Elex 334 manufactured by Matsumoto Yushi Co., Ltd. was used. When the SP value was calculated from the gas chromatographic composition, it was 9.80.)

As the polyolefin, polypropylene having a melt index of 2.0 / 10 minutes and a crystallinity of 98.4% was used. The blending ratio of the antistatic agent was added as shown in Table 2, and melt-kneaded with a different-direction twin screw extruder to obtain a film from a T-die. This film was stretched by a simultaneous bi-directional stretching machine (stretching ratio: 3.5 × 3.5) to obtain a stretched film having a thickness of 25 μm.
This stretched film is subjected to a corona surface treatment so as to have a wetting index of 40, and a water-based ink (JW250 Acqua Ecole manufactured by Toyo Ink Co., Ltd.) is printed using a gravure printing machine. Antistatic properties (surface resistivity) were examined. Printability and ink adhesion were evaluated 24 hours after printing. Antistatic properties and bleeding were measured 24 hours after film formation. The measurement method for each item is shown below.

(1) Adhesiveness of ink A cellophane pressure-sensitive adhesive tape is applied to the printed surface and rubbed five times from the top to be completely adhered. Thereafter, the cellophane pressure-sensitive adhesive tape was peeled off at once, and the adhesiveness of the ink was judged from the remaining state of the ink on the printed surface.
The evaluation criteria are as follows.

A: Ink remaining area is 95% or more. B: Ink remaining area is 85% to less than 95%. Δ: Ink remaining area is 75% to less than 85%. X: Ink remaining area is less than 75%.

(2) Printability of ink The printed surface of 150 lines / inch was observed with a microscope, and the printability (missing, repelling, spreading) of each line was judged according to the following criteria.

A: Ratio of occurrence of ink omission, repellency, and spread is less than 10%. O: Occurrence ratio of ink omission, repellency, and spread is 10% to less than 30%. △: Ratio of occurrence of ink omission, repellency, and spread is 30. % To less than 50% ×: The ratio of ink missing, repelling and spreading is 50% or more

(3) Surface resistivity It measured according to JIS-K6911.

(4) Bleedability Sensory evaluation was performed on the bleed on the film surface.

◎: No stickiness ○: Slightly sticky, but no problem in practical use △: Slightly sticky, there is a problem in practical use ×: Stickiness The measurement results are shown in Table 2.

Claims (2)

100 parts by mass of polypropylene film contains 0.1 to 2.0 parts by mass of an antistatic agent having a solubility parameter (SP value) of 11.1 to 12.0, which is a mixture of the following A to D compound groups. And
The mixture of the A to D compound groups is a mixture (A to C compound group mixture) selected from each of two or three compound groups of the following A to C compound groups, and D selected from the following D compound groups Charging characterized in that the mass ratio of the A to C compound group mixture and the D compound is (A to C compound group mixture) / D compound = 40/60 to 80/20. Prevention polypropylene film.
Compound A group:
Glycerin fatty acid monoester B compound group which is an ester of glycerin and a fatty acid having 12 to 18 carbon atoms and has an SP value in the range of 10.5 to 11.5.
Diglycerin fatty acid partial ester that is an ester of diglycerin and a fatty acid having 12 to 18 carbon atoms and has an SP value in the range of 11.0 to 12.5 C compound group:
Sorbitan fatty acid partial ester which is an ester of sorbitan and a fatty acid having 12 to 18 carbon atoms and has an SP value in the range of 9.0 to 13.0 D compound group:
Polyoxyethylene alkylamine or polyoxyethylene alkenylamine obtained by adding 2 to 3 moles of ethylene oxide to 1 mole of alkylamine or alkenylamine having 12 to 18 carbon atoms and fatty acid having 12 to 18 carbon atoms An amine ester compound having an SP value in the range of 9.0 to 10.0. The antistatic polypropylene film according to claim 1, wherein the polypropylene film is obtained by a biaxial stretching method, and is printed with water-based ink on at least one side.