JP2763338B2 - Antistatic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is suitable as a packaging film used for individual packaging, interior decoration, and exterior packaging of foods and the like, particularly as a packaging film subjected to printing or lamination. It relates to an antistatic film.

[Prior art and problems to be solved by the invention] Various plastic films are used as packaging films for foods and the like.
Printing and lamination are performed. On the other hand, plastic films generally have high electrical insulation properties, so they are easily charged with static electricity, causing various problems such as deterioration of printing and laminating properties, dust absorption during storage, and ignition due to sparks. In addition, when applied to food packaging, etc., problems with hygiene and appearance are likely to occur due to dust absorption.

In view of the above, in order to ensure printing and laminating workability, etc., one surface of the base film is subjected to corona discharge treatment, and an antistatic layer is provided on the other non-treated surface in order to solve problems caused by static electricity. An antistatic film on which is formed is known.

However, in such an antistatic film,
When printing or laminating by mistake is performed on the surface of the base film on which the antistatic layer is formed, the adhesive strength and the laminating strength between the base film and the printing ink are significantly reduced.
That is, the antistatic agent in the antistatic layer is eluted by the solvent contained in the printing ink or the solvent used during lamination, and this antistatic agent is usually a surfactant such as a quaternary ammonium salt. Then, because the eluted antistatic agent dissolves in the printing ink and this is the same as when applying the printing ink to the non-treated surface of the base film, the adhesive strength and lamination strength between the base film and the printing ink may be reduced. Difficult to secure.

Furthermore, there is a problem that printing suitability and laminating suitability can be secured only on one surface of the base film, that is, the surface subjected to corona discharge treatment, and printing and laminating are restricted.

Therefore, an object of the present invention is to provide an antistatic film that has excellent antistatic properties and can secure adhesion and lamination strength with a printing ink even when printing or laminating a surface on which an antistatic layer is formed. To provide.

Another object of the present invention is to provide an antistatic film which can be printed or laminated on any side of the film.

[Constitution of the Invention] As a result of intensive studies, the present inventor has found that when an antistatic layer is formed on a corona discharge-treated surface of a substrate film, even if the antistatic layer is subjected to printing or laminating processing, the printing ink can be used. The present invention was completed by finding that the adhesion and the lamination strength did not decrease. That is, the present invention provides an antistatic property in which at least one surface of the base film is subjected to corona discharge treatment, and an antistatic layer composed of an antistatic agent and a binder resin is formed on the surface-treated surface. This object is achieved by a film. Also,
The present invention solves the above-mentioned problem by an antistatic film in which both surfaces of a base film are subjected to corona discharge treatment and an antistatic layer is formed on at least one surface of the base film.

The base film is not particularly limited and various film materials, for example, polyethylene, ethylene-ethyl acrylate copolymer, ionomer, polypropylene,
Olefinic resins such as ethylene-propylene copolymer and poly-4-methylpentene-1; polyvinyl chloride; vinylidene chloride such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer and the like. Resins; Styrene resins such as polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer; polyesters such as polyethylene terephthalate and polybutylene terephthalate; nylons or polyamides such as 6-nylon and 66-nylon; polyacrylonitrile A polycarbonate;
Polyimide; polyvinyl alcohol; ethylene-vinyl acetate copolymer and saponified product thereof; cellophane; cellulose such as cellulose acetate; Among the above substrate films, films made of polyolefin-based resin, particularly polypropylene films, and films made of polyester, particularly polyethylene terephthalate film have mechanical properties,
Excellent transparency and packaging suitability.

The base film is stretched by roll stretching, rolling stretching, belt stretching, tenter stretching, or tube stretching.
It may be uniaxially or biaxially stretched to an appropriate magnification. The base film may be a single-layer film, or a composite film in which two or more films are laminated in order to enhance the functionality of the film. The thickness of the base film is not particularly limited, and for example, a base film having a thickness of about 1 to 250 μm can be used.

At least one surface of the base film has been subjected to corona discharge treatment. It is sufficient that at least one surface of the substrate film is subjected to corona discharge treatment, and it is preferable that both surfaces are surface-treated. When both surfaces of the base film are subjected to the corona discharge treatment, the adhesion to the printing ink and the lamination strength can be secured on any surface. As the surface treatment of the base film, corona discharge treatment is preferable. According to this corona discharge treatment, the degree of surface treatment of the substrate film can be easily and easily controlled. The treatment degree of the base film is not particularly limited as long as the adhesion with the antistatic layer can be ensured, but is usually 35 to 50 dyn / cm, preferably 37 to 45 dyn / cm.
cm.

The base film may contain various additives such as an antioxidant, an ultraviolet absorber, a crystal nucleating agent, a lubricant, and a dye pigment.

An antistatic layer is formed on the corona discharge treated surface of the base film. This antistatic layer may be formed on both sides of the base film when both sides of the base film are surface-treated, but from the viewpoint of economical efficiency and workability,
It is preferably formed on one surface of the substrate film. In the case of a film in which both surfaces of the base film are subjected to corona discharge treatment and an antistatic layer is formed on one surface, the printability is improved not only on the other corona discharge treated surface but also on the surface on which the antistatic layer is formed. And laminating processability can be secured.

This antistatic layer contains an antistatic agent and a binder resin as main components. As antistatic agents,
Conventional antistatic agents, for example, ionic or nonionic, and are not particularly limited as long as they impart conductivity, and cationic, anionic, amphoteric and nonionic antistatic agents are all used. Can be used.

Examples of the cationic antistatic agent include polyoxyethylene alkylamines; hydantoin derivatives; pyridinium derivatives such as laurylpyridinium bromide; alkyltrimethylammonium chlorides such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, and dialkyldimethyl. Examples include quaternary ammonium salts such as ammonium chloride, polyvinylbenzyltrimethylammonium chloride and poly-2-acryloyloxyethyltrimethylammonium chloride; vinyl ether derivatives; acrylamide derivatives. Of these cationic antistatic agents, quaternary ammonium salts and the like are preferred.

Examples of the anionic antistatic agent include aryl sulfonates such as naphthalene sulfonate; alkyl aryl sulfonates such as dodecylbenzene sulfonate;
Fatty acid salts such as sodium oleate and potassium oleate; sulfuric acid derivatives such as sodium lauryl sulfate; triethanolamine salts of polystyrenesulfonic acid; Among these anionic antistatic agents, alkylaryl sulfonates and the like are preferable.

Examples of the amphoteric antistatic agent include alkyl betaines such as dimethylalkyl betaine; alanine derivatives; imidazoline derivatives such as calcium salts of imidazoline-type amphoteric surfactants; and metal salts of diamine-type amphoteric surfactants. Among the amphoteric antistatic agents, alkyl betaine type antistatic agents and the like are preferable.

Nonionic antistatic agents include, for example, polyhydric alcohols; ethylene oxide adducts of higher alcohols; ethylene oxide adducts of alkylphenols such as polyoxyethylene nonylphenyl ether; glycerin monostearate, glycerin monooleate, sorbitan monostearate , Esters of polyhydric alcohols such as sorbitan tristearate, sorbitan monooleate, sorbitan triolate and fatty acids; diethylene glycol monostearate, diethylene glycol monooleate, polyoxyethylene mono or diolate, polyoxyethylene mono or distearate, polyoxyethylene Glycerin monostearate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate Polyoxyethylene fatty acid esters and polyoxyethylene sorbitan fatty acid esters and the like of. Among these nonionic antistatic agents, ethylene oxide adducts of alkyl phenols, polyoxyethylene fatty acid esters and polyoxyethylene sorbitan fatty acid esters are preferred.

Among the above various antistatic agents, a cationic antistatic agent and an amphoteric antistatic agent are preferable.

These antistatic agents may be the same or different, and may be used alone or in combination of two or more. The content of the antistatic agent is
There is no particular limitation as long as the conductivity can be imparted. The content of the antistatic agent is usually 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the binder resin.
More preferably, it is about 40 to 60 parts by weight. Antistatic agent
If the amount is less than 10 parts by weight, it is difficult to impart a sufficient antistatic property, and if it exceeds 100 parts by weight, the adhesion to the substrate film or the like is reduced.

Examples of the binder resin include polyethylene, polyolefin such as polypropylene, ionomer, polyvinyl acetate, ethylene-vinyl acetate copolymer, acrylic resin, methacrylic resin, ethylene-acrylate copolymer, polyester, polyamide, polyurethane,
Chlorinated polyolefins such as polyacetal, polyvinyl chloride, polyvinylidene chloride, chlorinated polypropylene,
Cellulosic resin, polystyrene, styrene-acrylic copolymer, styrene-butadiene copolymer, styrene-
Styrene resins such as acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-vinyl acetate copolymer, vinylidene chloride-acrylic acid Examples thereof include vinylidene chloride-based resins such as copolymers, vinylidene chloride-methacrylic acid copolymers, vinylidene chloride-acrylate copolymers, and vinylidene chloride-methacrylic acid ester copolymers.

These binder resins are used alone or in combination of two or more.

Further, the antistatic layer may contain an adhesive of an isocyanate type, an epoxy type, a polyethyleneimine type or the like in order to further increase the adhesion to the substrate film.

The antistatic layer contains additives such as an antioxidant, an ultraviolet absorber, a heat stabilizer, a wax, a saturated or unsaturated fatty acid amide, a fine powdery lubricant, an organic or inorganic filler, a dye pigment, and a viscosity modifier. May be contained.

The antistatic film of the present invention preferably has blocking resistance and slip properties from the viewpoint of workability. The anti-blocking property and the slip property may be imparted by forming an anti-blocking layer and a lubricant layer on the antistatic layer, but the antistatic layer preferably contains a lubricant.

As the lubricant, wax or a fine powdery lubricant is preferable.
Examples of the wax include hydrocarbon waxes such as paraffin wax, polyethylene wax and microcrystalline wax, fatty acid waxes such as stearic acid, monoglyceride stearate, triglyceride stearate, zinc stearate, calcium stearate, oleic acid amide, and stearin Various waxes such as fatty acid amide waxes such as acid amide, erucamide, methylene bisstearic acid amide and ethylene bisstearic acid amide, and ester waxes such as carnauba wax can be exemplified. At least one of the above waxes is used. When the wax is contained in the antistatic layer, the content of the wax is usually 1 to 150 parts by weight, preferably 25 to 125 parts by weight, more preferably 50 to 100 parts by weight, based on 100 parts by weight of the binder resin. It is about. If the amount of the wax is less than 1 part by weight, the slipperiness is not sufficient, and if it exceeds 150 parts by weight, transparency and the like are liable to be lowered.

As fine powder lubricant, for example, kaolin, talc,
Inorganic lubricants such as diatomaceous earth, titanium oxide, calcium carbonate, magnesium carbonate, barium sulfate, silica, and alumina; organic lubricants such as polyethylene, polypropylene, polystyrene, acrylic resin, silicone resin, and phenolic resin; alumina valves, silica balloons, and foamed glass ,
A micro hollow body such as a micro balloon and Saran microsphere is exemplified. Among these fine powdery lubricants, silica fine powder, alumina fine powder, polyethylene fine powder,
Acrylic fine powder is preferred. The fine powdery lubricant may have an appropriate particle size in a range that does not impair transparency or the like,
It is preferably 5 μm or less. When the particle size exceeds 5 μm, the lubricant tends to be missing, and the workability during packaging and the like is reduced. The content of the fine powdery lubricant is usually 10
The amount is 1 to 50 parts by weight, preferably 5 to 40 parts by weight, and more preferably about 10 to 30 parts by weight with respect to 0 parts by weight. If the amount of the fine powdery lubricant is less than 1 part by weight, the lubricating property is not sufficient, and if it exceeds 50 parts by weight, the transparency and the like of the film tend to be lowered.

The thickness of the antistatic layer is not particularly limited, but is usually 0.001 to 5 μm, preferably 0.01 to 2.5 μm, and more preferably 0.05 to 1 μm. When the thickness is less than 0.001 μm, the antistatic effect is reduced, and when it exceeds 5 μm, it is not economical, and in some cases, the properties of the base film may be reduced.

According to the antistatic film of the present invention, since the antistatic layer is formed on the corona discharge treated surface of the base film, the adhesion between the base film and the antistatic layer is excellent, and the antistatic property is long-term. Can be maintained throughout. In addition, since an antistatic layer composed of an antistatic agent and a binder resin is formed on the surface-treated surface of the base film, even if the antistatic layer is subjected to printing or laminating, the adhesive strength with the printing ink and the lamination. Strength can be ensured, and printing and laminating properties are excellent. The reason why the adhesion to the printing ink does not decrease even when the printing or the like is performed on the antistatic layer is because the polar group is generated on the surface of the base film by the surface treatment, and is included in the printing ink and the like. It is presumed that the antistatic agent was eluted by the solvent and the printing ink was firmly adhered to the surface-treated surface of the base. In the work line until printing ink is printed or laminated,
Excellent workability can be ensured by the antistatic layer.

The antistatic film of the present invention is subjected to a corona discharge treatment on at least one surface of the substrate film, and the surface treatment surface,
It can be produced by applying a coating solution containing the antistatic agent and the binder resin. An organic solvent is usually used for preparing the coating liquid. Examples of the organic solvent include alcohols such as methanol, ethanol, and isopropanol; aliphatic or alicyclic hydrocarbons such as hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene and toluene; methylene chloride; and tetrachloride. Halogenated hydrocarbons such as carbon, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as methyl acetate and ethyl acetate, ethers such as dioxane, diethyl ether and tetrahydrofuran, and mixed solvents thereof are used. The organic solvent can be appropriately selected depending on the solubility of the binder resin, the stability of the coating solution, and the like. The coating liquid can be prepared using a general mixer.

The coating liquid is applied to the substrate film using a conventional coating means, for example, a coating means such as a dip coater, a roll coater, a flow coater, a knife coater, a gravure coater, an air knife coater, and a spray, and dried. As a result, an antistatic film is obtained.

[Effects of the Invention] As described above, according to the antistatic film of the present invention, at least one surface of the base film is subjected to corona discharge treatment, and the surface treatment is performed with an antistatic agent and a binder resin. Since the formed antistatic layer is formed, the antistatic property can be ensured for a long period of time, and even if printing or laminating is performed on the surface on which the antistatic layer is formed, the base film and the printing ink can be used. Adhesion and lamination strength can be secured.

In addition, in the case of an antistatic film in which an antistatic layer is formed on at least one surface of the substrate film, both surfaces of the substrate film are subjected to corona discharge treatment, and any surface of the film can be subjected to printing or laminating. .

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples.

Example 1 One surface of a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was subjected to surface tension of 40 dyn /
cm.

In addition, 50 parts by weight of chlorinated polypropylene, 50 parts by weight of sodium dodecylzensulfonate, 8 parts by weight of silica fine powder, and a mixed solvent of ethyl acetate-toluene (2: 1 by weight) are mixed to form a solid matter concentration of 0.4% by weight. A liquid was prepared. Then, the coating liquid was applied to the surface-treated surface of the above-mentioned film so as to have a coating amount after drying of 0.05 g / m ^2, and dried to form an antistatic layer.

Example 2 One surface of a biaxially stretched polypropylene film having a thickness of 20 μm was subjected to corona discharge treatment in the same manner as in Example 1, and the surface-treated surface was treated with methyl ethyl ketone, 60 parts by weight of a vinyl chloride-vinyl acetate copolymer, and stearyl trimethyl. A coating solution comprising 40 parts by weight of ammonium chloride and 5 parts by weight of silica fine powder was applied and dried in the same manner as in Example 1 to form an antistatic layer.

Example 3 An antistatic layer was formed in the same manner as in Example 1 except that polyoxyethylene nonylphenyl ether was used as an antistatic agent instead of sodium dodecylbenzenesulfonate.

Example 4 Corona discharge treatment was applied to both surfaces of the biaxially stretched polyethylene terephthalate film of Example 1, and the coating solution of Example 1 was applied to one surface of the film in the same manner as in Example 1 and dried. To form an antistatic layer.

Comparative Example 1 An antistatic layer was formed in the same manner as in Example 1 without performing corona discharge treatment on the biaxially stretched polyethylene terephthalate film of Example 1.

Comparative Example 2 An antistatic layer was formed in the same manner as in Example 2 without performing corona discharge treatment on the biaxially stretched polypropylene film of Example 2.

The characteristics of the sample films obtained in each of the above Examples and Comparative Examples were evaluated as follows.

(1) Antistatic property: Surface resistivity was measured.

(2) Slippery: The coefficient of kinetic friction was measured at a temperature of 20 ° C. and a relative humidity of 65% RH.

(3) Blocking resistance: The antistatic layer surfaces of the sample films were overlapped with each other, a load of 40 g / cm ² was applied, and the samples were allowed to stand at a temperature of 30 ° C. and a relative humidity of 80% RH for 10 days. Then, the shear peel strength of a sample film having a width of 15 mm was measured by a Tensilon tensile test, and evaluated based on the following criteria.

Excellent: Less than 200g Good: 200g or more and less than 1000g Impossible: 1000g or more (4) Adhesion with printing ink: Gravure printing ink (trade name: Lamister, manufactured by Toyo Ink Co., Ltd.) The surface of the film on which the antistatic layer was formed And dried. Next, an adhesive tape (Nichiban Co., Ltd., Cellotape) is adhered to the printing ink surface, the adhesive tape is instantly peeled off at an angle of 90 °, and the adhesion between the printing ink and the base film is determined according to the following criteria. evaluated.

Excellent: There is no peeling of the printing ink. Good: The printing ink is slightly peeled. Impossible: All the printing ink is peeled. (5) Laminating strength: Dry laminating unstretched polypropylene on the surface of the film on which the antistatic layer is formed The peel strength between the base film and the unstretched polypropylene film laminated was measured by a Tensilon tensile test under the condition that the width of the sample film was 15 mm.

 The results are shown in the table.

As is clear from the table, the films of Comparative Example 1 and Comparative Example 2 have insufficient adhesion to the printing ink and the strength of the laminate film, whereas the sample films of the respective examples have
Excellent adhesion to printing ink and lamination strength.
Further, the films of the examples were excellent in antistatic properties, slip properties, and blocking resistance.

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein at least one surface of the base film is subjected to a corona discharge treatment, and an antistatic layer composed of an antistatic agent and a binder resin is formed on the treated surface. Antistatic film. 2. The antistatic film according to claim 1, wherein both surfaces of the base film are subjected to a corona discharge treatment, and an antistatic layer is formed on at least one surface of the base film.