JP4750291B2 - Polyolefin multilayer film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is not limited to an oil-based ink layer, but relates to a polyolefin multilayer film having excellent adhesion to an aqueous ink printing layer and having antistatic properties.
[0002]
[Prior art]
Polyolefin film represented by polypropylene film is easier to be charged than film made of polar polymer such as polyamide film, and when used as it is for packaging film, it adsorbs dust in the air and easily blocks the film. Therefore, with almost no exception, an antistatic agent is added. However, it is known that when printed on a film surface to which an antistatic agent is added, particularly when printed with aqueous ink, the antistatic agent inhibits the adhesion of the aqueous ink.
[0003]
It has been proposed to add N-ethanolic acid amide or N, N-diethanolic acid amide as an antistatic agent that does not inhibit the adhesion of water-based ink (Japanese Patent Laid-Open Nos. 6-345904 and 7-164608). Publication). However, it has been found that even when an antistatic agent having such a structure is added, adhesion to water-based ink is still inhibited.
[0004]
[Problems to be solved by the invention]
Therefore, the present inventors aimed to conduct various studies in order to develop a polyolefin film that does not inhibit the adhesion with water-based ink and is excellent in antistatic properties.
[0005]
[Means for Solving the Problems]
That is, the present invention provides a polyolefin film, preferably a biaxially stretched polypropylene film, which can be obtained from a polyolefin composition containing 0.1 to 2% by weight of a partial ester of a polyhydric alcohol fatty acid, preferably a partial ester of glycerin fatty acid. It is a polyolefin multilayer film which does not impair adhesion with water-based ink and has excellent antistatic properties, characterized by having a printing layer, preferably a water-based ink printing layer.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Polyolefin The polyolefin according to the present invention is an α-olefin having 2 to 10 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like. Or a copolymer of two or more α-olefins, usually high pressure method low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutene, poly-4-methyl-1 -Commercially available as pentene or the like.
[0007]
The polyolefin is not particularly limited, but usually a polypropylene having a MFR (melt flow rate; ASTM D-1238 load of 2160 g, temperature of 230 ° C.) of 0.5 to 12 g / 10 min is obtained as a moldable film. It is preferable because of its excellent mechanical strength. Such polypropylene may be a homopolymer of propylene, a small amount of 0.1 to 6 mol% of a random copolymer with α-olefin such as ethylene and 1-butene, or a mixture thereof.
[0008]
Partial ester of polyhydric alcohol fatty acid The partial ester of polyhydric alcohol fatty acid according to the present invention includes polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, polyglycerin, pentaerythritol and caprylic acid, capric acid, laurin. Acids, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachidic acid, behenic acid and the like, usually saturated fatty acids having 7 to 21 carbon atoms, decenoic acid, undecenoic acid, dodecenoic acid, tetradecenoic acid, It is a partial ester with unsaturated fatty acids such as oleic acid, erucic acid, linoleic acid, linolenic acid, ricinoleic acid and the like. Specific examples of such partial esters include glycerol monocaprylate, glycerol monocaprate, glycerol monolaurate, glycerol monopalmitate, glycerol monostearate, glycerol mono12-hydroxystearate, glycerol monobehenate, glycerol mono (Poly) glycerin monoesters such as oleate, diglycerin laurate, diglyceryl stearate, diglycerin oleate, diglycerin caprylate, polyglycerin monostearate, glycerin mono-distearate, glycerin mono-di12-hydroxystearate, Examples include glycerol mono / dilysinate, glycerol mono / dipalmitate, glycerol mono / dibehenate, mono / diesters such as glycerol mono / diolate, etc. Among these, (poly) glycerin monoester is most preferable.
[0009]
Polyolefin composition The polyolefin composition according to the present invention is a polyolefin composition comprising 0.1 to 2% by weight, preferably 0.2 to 1% by weight of a partial ester of a polyhydric alcohol fatty acid in the polyolefin. Become. When the content of the partial ester of the polyhydric alcohol fatty acid is less than 0.1% by weight, the antistatic effect of the film is insufficient when made into a polyolefin film, while when the content exceeds 2% by weight, the film is blocked, Excess partial ester may bleed out on the film surface and the appearance of the film may be impaired.
[0010]
Polyolefin film The polyolefin film according to the present invention is a film obtained from the above polyolefin composition. Such a polyolefin film may be an unstretched film or a uniaxially or biaxially stretched film, but a polypropylene biaxially stretched film is preferable because it is excellent in transparency, rigidity, scratch resistance and the like. Such polyolefin films can be obtained by various known methods. The thickness of the polyolefin film is appropriately determined depending on the use, but is usually in the range of 5 to 100 μm, preferably 10 to 40 μm.
[0011]
The polyolefin film according to the present invention may be a single-layer film obtained from the above-mentioned polyolefin composition, or a polyolefin layer having a low melting point compared to a polyolefin that forms a single-layer film on one side or both sides of the single-layer film. -Other layers, such as a layer added with a blocking agent, may be formed. The thickness of such other layers is usually in the range of 0.5 to 5 μm, preferably 0.5 to 3 μm. If the layer becomes thick, the partial ester of polyhydric alcohol fatty acid added to the polyolefin film is difficult to ooze out to the film surface through the layer, so that the antistatic effect of the resulting polyolefin film may be difficult to express.
[0012]
For the polyolefin film of the present invention, various heat-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, lubricants, slip agents, nucleating agents, anti-blocking agents, pigments, dyes, inorganic or organic fillers and the like usually used for polypropylene You may add an additive in the range which does not impair the objective of this invention.
[0013]
Polyolefin multilayer film The polyolefin multilayer film of the present invention comprises a water-based ink printing layer on at least one side of the polyolefin film. The surface on which the water-based ink of the polyolefin film is printed is subjected to surface treatment such as corona discharge treatment, plasma discharge treatment, flame treatment, etc., and the antistatic effect due to the partial ester of polyhydric alcohol fatty acid is expressed, and water-based This is preferable because the adhesiveness of the ink is improved.
[0014]
Various known water-based inks for forming the water-based ink printing layer of the polyolefin multilayer film of the present invention can be used. Such water-based inks are composed of inorganic pigments, pigments composed of organic pigments and dyes as dyes, vehicles in which resins are dispersed or dissolved, surfactants, antistatic agents, antifoaming agents, plasticizers and other auxiliary agents. Examples of the resin include water-soluble acrylic copolymer resins, polyester resins, aqueous polyurethane resins, and aqueous polyamide resins. The water-based ink may contain a small amount, for example, 40% or less alcohol. In addition, the polyolefin multilayer film of the present invention is laminated with other resin layers such as a low-melting-point polyolefin layer excellent in low-temperature heat sealability, polyester, polyamide, ethylene / vinyl alcohol copolymer layer excellent in gas barrier properties, and the like. May be.
[0015]
【The invention's effect】
The polyolefin multilayer film of the present invention is characterized in that the printing layer, particularly the water-based ink printing layer, is sufficiently transferred to the polyolefin film, so that the printing layer is clear and the antistatic property is excellent. Therefore, the polyolefin multilayer film of the present invention is preferably used for packaging films in various fields such as food packaging films, cassette tapes, floppy disk packaging films for electronic information materials, cigarette packaging films, etc., taking advantage of such characteristics. it can.
[0016]
【Example】
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.
[0017]
Reference Example 6
A polypropylene composition having a melting point of 162 ° C. containing 0.5% by weight of glycerol monolaurate and a MFR of 2.0 g / 10 min is used as a core layer, and an anti-blocking agent comprising polymethyl methacrylate particles on both sides (skin layer) is 0.12 After extruding a three-layer film made of a polypropylene composition having a melting point of 162 ° C. and a MFR of 2.4 g / 10 min, the longitudinal draw ratio is 5 times (stretch temperature 115 ° C.), and the transverse draw ratio is 10 times ( After biaxial stretching at a stretching temperature of 160 ° C., one surface (printed surface) was subjected to corona discharge treatment to obtain a biaxially stretched polypropylene film comprising skin layer / core layer / skin layer: 1 μm / 23 μm / 1 μm. Next, on the surface of the obtained biaxially stretched film subjected to the corona discharge treatment, water-based ink manufactured by Toyo Ink Mfg. Co., Ltd. (trade name JW220 Acqua Ecole) was diluted with a solvent (trade name AQ602F) manufactured by Toyo Ink Mfg. Co., Ltd. Gravure printing was performed with a helio plate having 50 μm and 50 μm wide cells to obtain a multilayer film.
[0018]
The obtained multilayer film was evaluated by the following method.
[Printability] The spread of the ink transferred from the cell to the film was visually observed, and the spread that was more than twice as large as the cell area on the plate was ○, and the spread was equivalent to less than twice the cell area. An object was shown by Δ, and an object showing only a spread less than the cell area was indicated by ×.
[Surface Specific Resistance Value] The corona discharge treated surface before gravure printing was measured according to JIS K6911 using a digital ultrahigh resistance / microammeter R8340A and a resistance chamber R12704A manufactured by Advantest Corporation.
As a result, the printability of the multilayer film was good, and the surface specific resistance value was 1.4 × 10 ¹³ Ω. Both the printability and the surface specific resistance value showed good results.
[0019]
Example 2
The same procedure as in Reference Example 6 was performed except that glycerol monopalmitate was used instead of glycerol monolaurate used in Reference Example 6 . The resulting multilayer film had good printability and a surface specific resistance value of 3.6 × 10 ¹² Ω. Both the printability and the surface specific resistance value showed good results.
[0020]
Reference Example 7
The same procedure as in Reference Example 6 was performed except that glycerol monostearate was used instead of glycerol monolaurate used in Reference Example 6 . The printability of the obtained multilayer film was ○, the surface specific resistance value was 2.2 × 10 ¹⁵ Ω, and the surface specific resistance value was slightly inferior, but the printability was good.
[0021]
Reference Example 8
Instead of glycerol monolaurate that used in Reference Example 6, except for using diglycerol monostearate, it was carried out in the same manner as in Reference Example 6. The printability of the obtained multilayer film was ◯, the surface resistivity was 8.4 × 10 ¹⁵ Ω, and the surface resistivity was slightly inferior, but the printability was good.
[0022]
Reference Example 9
Instead of glycerol monolaurate that used in Reference Example 6, a except for using composition containing 0.25 wt% of triglycerol monostearate, were carried out in the same manner as in Reference Example 6. The printability of the obtained multilayer film was ○, the surface resistivity was 8.3 × 10 ¹⁵ Ω, and the surface resistivity was slightly inferior, but the printability was good.
[0023]
Reference Example 10
Instead of glycerol monolaurate that used in Reference Example 6, a except for using composition containing 0.25 wt% tetraglycerol monostearate, were carried out in the same manner as in Reference Example 6. The printability of the obtained multilayer film was ◯, the surface specific resistance value was 5.7 × 10 ¹⁵ Ω, and the surface specific resistance value was slightly inferior, but the printability was good.
[0024]
Comparative Example 1
Instead of the composition used in Reference Example 6 , the same procedure as in Reference Example 6 was performed except that glycerin monolaurate was not added. Although the printability of the obtained multilayer film was ◯, the surface specific resistance value was as high as 5.7 × 10 ¹⁶ Ω and was inferior in antistatic property.
[0025]
Reference example 1
The same procedure as in Reference Example 6 was performed except that lauric acid diethanolamide was used instead of glycerin monolaurate used in Reference Example 6 . The obtained multilayer film had a surface resistivity value as low as 5.3 × 10 ¹² Ω, but the printability was Δ and the film was inferior in printability.
[0026]
Reference example 2
The same procedure as in Reference Example 6 was performed except that palmitic acid diethanolamide was used instead of glycerin monolaurate used in Reference Example 6 . The obtained multilayer film had a low surface resistivity of 1.1 × 10 ¹² Ω, but the printability was Δ and the film was inferior in printability.
[0027]
Reference example 3
The same procedure as in Reference Example 6 was performed except that lauryl diethanolamide was used instead of glycerin monolaurate used in Reference Example 6 . The obtained multilayer film had a surface specific resistance value as low as 2.0 × 10 ¹¹ Ω, but the film was inferior in printability with Δ.
[0028]
Reference example 4
The same procedure as in Reference Example 6 was performed except that myristyl diethanolamide was used instead of glycerin monolaurate used in Reference Example 6 . The obtained multilayer film had a surface specific resistance value as low as 1.4 × 10 ¹¹ Ω, but the printability was poor and the printability was poor.
[0029]
Reference Example 5
The same procedure as in Reference Example 6 was performed except that betaine was used instead of glycerin monolaurate used in Reference Example 6 . The obtained multilayer film had a surface resistivity value as low as 4.3 × 10 ¹¹ Ω, but the printability was Δ and the film was inferior in printability.

Claims (4)

A polyolefin multilayer film comprising a printed layer on at least one surface of a polyolefin film that can be obtained from a polyolefin composition containing 0.1 to 2% by weight of a partial ester of a polyhydric alcohol fatty acid comprising glycerin monopalmitate . The polyolefin multilayer film according to claim 1, wherein the printing layer is a water-based ink printing layer. The polyolefin multilayer film according to claim 1 or 2, wherein the polyolefin is polypropylene. The polyolefin multilayer film according to claim 1, wherein the polyolefin film is biaxially stretched.