JPH0662019B2 - Label based on polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is based on a polyester having improved adhesion,
The present invention relates to a label provided with a printing layer made of a printing ink that is cured by air, ultraviolet rays, or an electron beam. Labels are quality indicators,
It is used in various fields such as food, medicine, electronics, medical care, information industry, automobile, building materials industry, office supplies, business form, daily necessities, etc. for the purpose of quality assurance, price tag, advertisement, sealing, information instruction, etc.

[Conventional technology]

Label, "Adhesion", Vol. 28, No. 10, pp. 453-45
As shown in page 8 (issued in 1984), as a basic structure, an adhesive material layer is provided on a surface base material and the adhesive material layer is protected by a release paper. As the surface substrate, polyester, particularly polyethylene terephthalate film is used for applications requiring transparency, mechanical strength, dimensional stability, water resistance, solvent resistance, heat resistance and the like. The label needs to be printed on the surface base material to have a display function. As the printing method, screen printing, offset printing, gravure printing, and the like are used according to the quantity of printing. As the printing ink, an ink corresponding to this printing method is used, and the ink is of a solvent type or a solventless type. Oxidation polymerization (air curing), ultraviolet curing, and electron beam curing are used for so-called drying of the solventless ink layer. Many types of labels are printed in small quantities, often in small to medium-sized printing stations, and because of pollution control, solvent-free inks, especially air-curable and UV-curable inks, are used. ing. However, the adhesiveness between this solvent-free ink and the polyester film is insufficient, and depending on the application, it is necessary to form an undercoat layer during the label manufacturing process or before printing. Therefore, there has been a demand for a polyester film having improved printing ink adhesion in advance.

[Object of the Invention]

It is an object of the present invention to provide a polyester film with improved adhesion to solventless printing inks.

[Structure of Invention]

In order to achieve the above object, the present invention provides a polyester film on which at least one surface of a polyester film is coated with a coating agent containing a polyurethane having an anionic group having water as a main medium as an essential component and then stretched. A printing layer is formed on the.

The polyester film in the present invention is preferably polyethylene terephthalate in which 80 mol% or more of its constituents is ethylene terephthalate, or polyethylene naphthalate film in which 80 mol% or more is ethylene naphthalate. Ethylene terephthalate, polyester copolymer components other than ethylene naphthalate, diethylene glycol, propylene glycol,
A diol component such as neopentyl glycol, 1,4-pentylene glycol, 1,4-cyclohexanedimethanol, polyethylene glycol, polytetramethylene glycol, isophthalic acid, 5-sodiosulfoisophthalic acid, adipic acid, sebacic acid and the like. A dicarboxylic acid such as an ester-forming derivative, an oxycarboxylic acid such as oxybenzoic acid and an ester-forming derivative thereof, and the like can be used, but the present invention is not limited thereto.

The polyester film may be unstretched, but preferably stretched, and particularly preferably biaxially stretched. The thickness of the polyester film is preferably 5μ to 300μ.

If necessary, an antistatic agent may be added to the polyester film.
It may contain stabilizers, organic lubricants, inorganic fine particles, pigments, dyes, synthetic resins and the like.

The polyurethane having an anionic group using water as a medium in the present invention includes Japanese Patent Publication Nos. 42-24194 and 4
6-7720, Japanese Patent Publication No. 46-10193, Japanese Patent Publication No. 49
Known polyurethanes such as JP-A-37839, JP-A-50-123197, JP-A-53-126058, JP-A-54-138098, or polyurethanes similar thereto can be used.

The main constituents of the polyurethane-forming component are polyisocyanates, polyols, chain extenders, crosslinkers and the like.

Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-
Examples include dicyclohexylmethane diisocyanate and isophorone diisocyanate.

Examples of polyols include polyoxyethylene glycol, polyoxypropylene glycol, polyethers such as polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polyesters such as polycaprolactone, acrylic polyols, castor oil. and so on.

Examples of chain extenders or crosslinking agents include ethylene glycol, propylene glycol, butanediol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, water and the like.

Polyurethane having an anionic group is a polyurethane-forming component polyol, polyisocyanate compound,
A method of using a compound having an anionic group as a chain extender, a method of reacting an unreacted isocyanate group of a generated polyurethane with a compound of an anionic group, and a reaction of a group having an active hydrogen of polyurethane with a specific compound. It can be manufactured using a method or the like.

In the method of using a compound having an anionic group as the polyurethane-forming component, for example, a compound obtained by a method of sulfonating an aromatic isocyanate compound, a diaminocarboxylic acid salt, a sulfuric acid ester salt of amino alcohols, or the like can be used.

In the method of reacting an unreacted isocyanate group of a polyurethane with a compound having an anionic group, for example, bisulfite, aminosulfonic acid and salts thereof, aminocarboxylic acid and salts thereof, sulfuric acid ester of amino alcohols and salts thereof, hydroxy Acetic acid and its salts can be used.

In the method of reacting a specific compound with a group having active hydrogen of polyurethane, for example, dicarboxylic acid anhydride,
Tetracarboxylic acid anhydride, sultone, lactone, ethoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isatoic acid anhydride, hoston, carbyl sulfate or other salt type group or group capable of forming a salt after ring opening. A 3- to 7-membered cyclic compound represented by can be used.

The polyurethane is preferably a resin composed of a polyol having a molecular weight of 300 to 20,000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group reactive with an isocyanate group, and a compound having at least one anionic group.

Anionic groups in the _{polyurethane, -SO 3 H, -OSO 3 H} ,
Used as COOH and their ammonium, lithium, sodium, potassium or magnesium salts.

The amount of anionic groups in the polyurethane is 0.05% by weight to 8%.
Weight percent is preferred. When the amount of anionic groups is small, the water solubility or water dispersibility of the polyurethane resin is poor, and when the amount of anionic groups is large, the water resistance of the undercoat layer after application is poor or the polyurethane resin does not absorb moisture. This makes it easier for the films to stick to each other.

Polyurethane has good adhesiveness to printing ink, but has poor applicability and adhesiveness to a polyester film, which may cause practical problems. There is also a method of using a so-called surfactant for improving the coating property,
Surfactants are not preferable in that they may cause so-called plumming to become sticky or reduce adhesiveness.
In such a case, the coating property on the polyester film, regardless of the adhesiveness or stickiness of the printing ink,
There is a method of blending polyurethane having good adhesiveness with polyurethane having good adhesiveness of printing ink within a range not deteriorating the adhesiveness of printing ink. Further, as a preferable method for improving the coating property and the adhesive property of the polyurethane to the polyester film, there is a method of blending a polyester having a sulfonate group with water as a medium in the polyurethane coating agent of the present invention. As this polyester, Japanese Patent Publication No. S47-408
73, JP-A-50-83497, and JP-A-50-12.
Known polyesters such as those described in JP-A No. 1336 and JP-A No. 52-155640, or polyesters similar thereto can be used.

For example, as the dicarboxylic acid component of polyester, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and their ester-forming derivatives are used as examples of aromatic dicarboxylic acids, and examples of aliphatic dicarboxylic acids are used. , Adipic acid, azelaic acid, sebacic acid, and their ester-forming derivatives are used, and examples of oxymonocarboxylic acid include oxybenzoic acid and its ester-forming derivatives.

Further, as the glycol component of the polyester, aliphatic, alicyclic, aromatic diol and the like can be used, and examples thereof include ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol and 1,4.
-Cyclohexanedimethanol, p-xylenediol, etc. are used, and examples of poly (oxyalkylene) glycols are so-called polyethylene glycol, polypropylene glycol, polytetramethylene glycol,
Are used.

As the polyester, not only the saturated linear polyester including the ester-forming component described above but also a polyester including a compound having three or more ester-forming components or a polyester having a reactive unsaturated group can be used.

The polyester having a sulfonate group can be produced by using a compound having a sulfonate group which can be a polyester component together with the above-mentioned polyester forming component.

Examples of the compound having a sulfonate group include sulfoisophthalic acid, sulfoterephthalic acid, sulfonaphthalene-
There are metal salts such as 2,6-dicarboxylic acid and its ester-forming derivatives. As the metal of the metal salt, lithium, sodium, potassium, magnesium and the like are preferable. Among these, very suitable compounds include 5-
There are sodiosulfoisophthalic acid or 5-sodiosulfodimethylisophthalate.

Another method of introducing a sulfonate group into the polyester is to sulfonate the unsaturated group of the polyester containing an ester-forming aliphatic unsaturated compound as a copolymerization component with a sulfonating agent such as sodium hydrogen sulfite or sodium metabisulfite. The method can also be illustrated.

The amount of aromatic dicarboxylic acid in the dicarboxylic acid component of the polyester resin is preferably in the range of 50 mol% to 100 mol%. This is to increase the softening point of the polyester resin and improve the adhesiveness.

The sulfonate group in the polyester resin needs to be present in an amount necessary for making the resin water-soluble or water-dispersible, and the dicarboxylic acid having a sulfonate group is contained in an amount of 2 mol% to 20 mol% in the dicarboxylic acid. It is preferably used in the range.

If the amount of the sulfonate group is less than 2 mol%, the water solubility or water dispersibility is insufficient, and if the amount of the sulfonate group is more than 20 mol%, the water resistance of the undercoat layer after coating is poor, or the film absorbs moisture to absorb the film. The reason is that they tend to stick to each other.

Further, as the polyester resin, not only the saturated linear polyester including the above-mentioned ester-forming component but also 3
It is also possible to use a polyester composed of a compound having an ester-forming component having a valency or more or a polyester having a reactive unsaturated group.

When the polyester having a sulfonate group is blended with the polyurethane of the present invention, the solid content is 3 to 50 parts, more preferably 5 parts, relative to 100 parts of the polyurethane.
~ 30 parts. When the amount of polyester is more than 50 parts, the printing ink adhesion of polyurethane may not be exhibited, and when the amount of polyester is less than 3 parts,
The effect of improving the coating property and the effect of improving the adhesive property of polyester may be unclear.

A method of applying the polyurethane of the present invention to a polyester film is described by Yuji Harasaki, Maki Shoten, 1979, "Reverse Roll Coater",
A gravure coater, a rod coater, an air doctor coater, or a coating device other than these can be used. The coating process is before sequential secondary stretching in the film forming process, before simultaneous biaxial stretching, after biaxial stretching and before re-stretching, after film formation before winding, or outside the film forming process. A preferred coating method is a coating and stretching method in which a coating agent is coated on at least one side of a polyester film and then appropriately dried or stretched without drying. As a specific example of this method, a coating agent is applied to a uniaxially stretched polyester film by a roll stretching method, and appropriate drying is performed,
Alternatively, it is a method in which the material is immediately stretched in a direction perpendicular to the previous stretching direction without being dried, and heat-treated. According to this method, the coating layer can be dried simultaneously with stretching, and the thickness of the coating layer can be reduced according to the stretching ratio.

The thickness of the coating layer of the biaxially stretched polyester film of the present invention is preferably 0.01 μ to 1 μ, more preferably 0.01 μ to 0.5 μ. If the thickness of the coating layer is less than 0.01 μm, it is difficult to apply it uniformly, so that uneven coating is likely to occur on the product, and if it is thicker than 1 μm, the slipperiness may be rather deteriorated.

The coating agent of the present invention includes a urea-based agent, a melamine-based agent, a guanamine-based agent that is methylolated or alkylolated as a cross-linking agent to improve the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , Reactive with acrylamide type, polyamide type compounds, epoxy compounds, aziridine compounds, block polyisocyanates, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, heat, peroxides, actinic rays, etc. It may contain a vinyl-based compound or a photosensitive resin.

Further, the coating layer of the present invention, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide, barium salt, carbon black, sulfide as inorganic fine particles for the purpose of improving stickiness and slipperiness. It may contain molybdenum, antimony oxide sol, or the like.

In addition, the coating agent of the present invention is an antifoaming agent, a coating property improving agent, a thickener, an antistatic agent, an organic lubricant, an organic polymer particle, an antioxidant, an ultraviolet absorber, a foaming agent, if necessary. Agents, dyes,
It may contain a pigment or the like.

[Measurement and evaluation methods]

The measuring method of the adhesiveness of the printing ink of the present invention and the evaluation standard of the effect are based on the following methods.

1. Types of printing ink, printing method, and curing method (A) Tetoron, an air-drying ink from Jujo Chemicals
901 white (trade name, hereinafter abbreviated as A-1. The same applies hereinafter) and TAP # 9501 white (A-2) were solidly printed on a Tetoron 270 mesh screen and dried at room temperature for 12 hours.

(B) Toyo Ink's UV-curable ink FD-
A UV irradiation device made by Ushio Inc. after solid printing 100 parts of SS indigo and 5 parts of FD regulator (B-1) on a nylon 300 mesh screen.
VH-2000 type (trade name) with curing conditions of 160 W / c
UV curing was carried out at a film speed of 12 m / min.

(C) 100 parts of UVA-9119 which is an ultraviolet curable ink of Seiko Advance and 4 parts of SOX-120 white.
After printing 0 parts of the blended product (C-1) on a nylon 300 mesh screen, UV curing was carried out in the same manner as the B-1 ink except that the film speed was 4 m / min.

(D) PCD, a UV curable ink from Moroboshi Ink
White T Kai (D-1), CAR M Black HD (D-2), CA
After printing R M indigo (D-3) and CAR M medium Kai (D-4), which is an ultraviolet curable coating agent that imparts a matte tone, with an RT tester (trade name), which is an offset printing tester at Akira Seisakusho, UV curing was performed in the same manner as the B-1 ink.

2. Adhesiveness of printing ink Put 1mm square so-called goggles in the printing layer, and attach Nichiban cellophane tape with a width of 18mm to a length of 7cm to prevent air bubbles from entering it and then use a 3kg manual load roll. Apply a constant load.

Then, fix the film and attach one end of the cellophane tape to 5
Connected to a 00g cone and the cone is 45cm in distance, then 1
Adhesion was evaluated by the method of starting the peel test in the 80 ° direction.

Adhesiveness was evaluated according to the following 5 grades. 4 or more is a practical range.

5: There is no peeling on the surface of the cellophane tape.

Only less than 4: 10% is peeled off to the surface of the cellophane tape. Practically, an index of 4 or more can be used without problems.

A part of 3:10 to 50% is peeled off to the side of the cellophane tape.

2: 50% or more of the part peels off to the side of the cellophane tape.

1: Peel off completely on the cellophane tape side.

Comparative Example 1 A-1, A-2, B-1, and C- were added to biaxially stretched polyethylene terephthalate film having thicknesses of 25 µ, 50 µ, and 75 µ.
Ink Nos. 1, D-1, D-2, D-3, and D-4 were each printed by the method described above, a peeling test was performed using cellophane tape, and the adhesiveness of the printing ink was evaluated. The evaluation was 1, which was not practical as a label film.

Example 1 The same polyethylene terephthalate as in Comparative Example 1 was melt extruded, and then a 250 μm lengthwise stretched film was obtained by a roll stretching method. Immedially on one side of this film, a Bayer Implanil D, a polyurethane with sulfonate groups.
LH (trade name) 70 parts (as solid content, same below),
A coating solution containing 20 parts of Hua Intex E4-670 (trade name) manufactured by Dainippon Ink and Co., Ltd., which is a polyester having a sulfonate group, and 1 part of alkylol melamine was used as a medium, and after lateral stretching, 230 The film was heat treated at ℃ to obtain a film having a thickness of 75μ. The thickness of the coating layer of this film was 0.12 g / m ² , the haze was 2.1%, and the static friction coefficient between the coating layer surface and the uncoated surface was 0.55. The printing ink adhesion to the coating layer surface of this film was evaluated with respect to the inks A-1, A-2, and D-2 by 4, B-1, C-1, D-1, D-3, D. -4 was evaluated as 5, and was useful as a film for labels.

Example 2 The same polyethylene terephthalate as in Comparative Example 1 was melt extruded and then a 90 μm lengthwise stretched film was obtained by a roll stretching method.
Immedially, on one side of this film, 65 parts of Inplanil DLH of Example 1 and 20 parts of Faintex ES-670 were immediately added.
Part, 10 parts of alkylol urea, and 5 parts of silica sol were mixed to apply a coating solution using water as a medium, and after lateral stretching, 230
The film was heat-treated at 0 ° C. to obtain a film having a thickness of 25 μm. The coating layer of this film has a thickness of 0.10 g / m ² and a haze of 1.
The coefficient of static friction between the coated layer surface and the uncoated surface was 6%. The printing ink adhesion to the coating layer surface of this film was evaluated with respect to B-1, C-1, and D-5.
It was useful as a label film.

Example 3 The same polyethylene terephthalate as in Comparative Example 1 was melt-extruded and then a roll-stretching method was used to obtain a 175-μ longitudinally stretched film. Immediately on one side of this film, a coating liquid containing water, which is a polyurethane having a carboxylate group and consisting only of Hydran AP-40 (trade name) of Dainippon Ink and Chemicals, is applied, and after lateral stretching, heat treatment is performed at 230 ° C. , Thickness 50
A film of μ was obtained. The thickness of the coating layer of this film was 0.08 g / m ² , the haze was 1.8%, and the coefficient of friction between the coating layer surface and the uncoated surface was 0.52. This film has printing ink adhesion to the coating layer surface of A-1, B
-1, C-1, and D-1 were evaluated as 5 and useful as a label film.

Example 4 Instead of the coating liquid of Example 1, hydrane AP- of Example 3 was used.
A film was obtained in the same manner as in Example 1 except that 80 parts of 40 (trade name) and 20 parts of Finetex ES-670 (trade name) of Example 1 were mixed to prepare a water-based coating solution. The thickness of the coating layer of this film is 0.12 g /
m ² , haze was 20%, and the static friction coefficient between the coated layer surface and the uncoated surface was 0.57. The adhesion of the printing ink to the coating layer surface of this film was evaluated with respect to D-2 by 4, A-1, A-2, B-1, C-1, D-1, D-.
3 and D-4 were evaluated as 5, and were useful as a label film.

Comparative Example 2 As a white pigment, polyethylene terephthalate containing 10% by weight of titanium oxide was melt-extruded and then a roll-stretch method was used to obtain a 175-μ longitudinally stretched film. The film was laterally stretched and then heat-treated at 230 ° C. to obtain a film having a thickness of 50 μm. The friction coefficient of this film was 0.32. The adhesion of printing ink to this film is B-1, C
-1, D-2, and D-3 were evaluated as 1 and were not practical as a label film.

Example 5 A film having a thickness of 50 μm was obtained in the same manner as in Comparative Example 2 after applying the coating solution of Example 4 to the longitudinally stretched film of Comparative Example 2. This film was white and opaque, the thickness of the coating layer was 0.12 g / m ² , and the coefficient of static friction between the coating layer surface and the uncoated surface was 0.35. The adhesion of the printing ink to the coating layer surface of this film was evaluated with respect to D-2 as 4, B.
-1, C-1, D-3 was evaluated as 1 and was useful as a label film.

〔The invention's effect〕

The label of the present invention, which is printed with a special ink, is made of a polyester film as a base material, which is obtained at a relatively low cost by a coating-stretching method and has a relatively wide coating film, and has good adhesion to a printing ink.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Kita 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Daifoil Co., Ltd. (72) Inventor Kakumei Okajima Kamoshida-cho, Midori-ku, Yokohama, Kanagawa (56) References JP-A-58-78761 (JP, A) JP-A-57-6767 (JP, A) JP-A-57-160694 (JP, A) JP-A-56-151562 (JP , A) JP-A-49-74779 (JP, A)

Claims (1)

[Claims] 1. A solvent-free, air-curable coating layer surface of a polyester film obtained by applying a coating agent containing a polyurethane having an anionic group in a water medium as an essential component on at least one side of a polyester film and then stretching it. A label characterized in that a printing layer is formed with any of a mold ink, an ultraviolet curable ink, and an electron beam curable ink.