JPS6297890A - Label with polyester film as base - Google Patents

Abstract

PURPOSE:To provide a polyester film improved in adhesion to a solventless-type printing ink, by applying a polyurethane having anionic groups to one side of a polyester film and then stretching the film. CONSTITUTION:A coating agent comprising water as a main medium and comprising a polyurethane having anionic groups as an essential constituent is applied to at least one side of a polyester film, the film is then stretched, and a printing layer is provided on the polyurethane layer. The polyester film is preferably a film of polyethylene naphthalate in which ethylene terephthalate or naphthalate constitutes at least 80mol% of the constituents. The polyurethane having the anionic groups can be prepared by a method in which a compound having an anionic group is used as either of a polyol compound, a polyisocyanate compound and the like which are used for forming the polyurethane, a method wherein unreacted isocyanate groups of a polyurethane formed are brought into reaction with a compound having an anionic group, or the like.

Description

[Detailed description of the invention] [Industrial application field] The present invention uses polyester with improved adhesiveness as a base material,
It relates to a label provided with a printing layer using printing ink that is cured by air, ultraviolet rays, or electron beams. The label indicates quality,
It is used in all fields such as food, medicine, electronics, medical care, information industry, automobiles, building material industry, office supplies, business forms, and daily necessities for purposes such as quality assurance, price tags, advertising, seals, and information instructions.

[Conventional technology]

The label is "Adhesion", Vol. 28, No. 10, pp. 453-4.
As shown on page 5B (published in 1984), the basic structure is that an adhesive layer is provided on the surface base material and the adhesive layer is protected with a release paper, which is often used due to its convenience. This surface base material has transparency, mechanical strength, dimensional stability,
Polyester, especially polyethylene terephthalate film, is used for applications that require water resistance, solvent resistance, heat resistance, etc. Labels require printing on the surface base material to provide display functions. Printing methods include screen printing, offset printing, and gravure printing, depending on the quantity of printing. Printing inks that are compatible with this printing method are used, and there are two types of inks: solvent-based and solvent-free. Oxidative polymerization (air curing), ultraviolet curing, and electron beam curing are used for so-called drying of solvent-free ink layers. Labels are often printed in small quantities of a wide variety of products, and are often carried out at small to medium-sized printing shops, and in order to prevent pollution, solvent-free inks, especially air-curing and ultraviolet-curing inks, are used. has been done. However, the adhesion between this solvent-free ink and polyester film is insufficient, and depending on the application, it may be necessary to form an undercoat layer during the label manufacturing process or before printing.
Polyester films with improved printing ink adhesion were required in advance due to increased process and cost increases.

[Purpose of the invention]

An object of the present invention is to provide a polyester film with improved adhesion to solvent-free printing inks.

[Structure of the invention]

In order to achieve the above object, the present invention forms a printing layer on the polyurethane layer of a polyester film that has been stretched after applying a coating agent containing polyurethane as an essential component having an anionic group to form a polydimeric film. .

The polyester film in the present invention is preferably a polyethylene terephthalate film in which 80 mol% or more of the constituent components are ethylene terephthalate, or a polyethylene naphthalate film in which 80 mol% or more of the constituent components are ethylene naphthalate. Polyester copolymerization components other than ethylene terephthalate and ethylene naphthalate include diethylene glycol, propylene glycol,
Diol components such as neopentyl glycol, 1゜4-butylene glycol, 1,4-cyclohexane dimetatool, polyethylene glycol, polytetramethylene glycol, isophthalic acid, 5-sodiosulfoisophthalic acid, adipic acid, sepacic acid and Dicarboxylic acids such as ester-forming derivatives thereof, oxycarboxylic acids such as oxybenzoic acid and ester-forming derivatives thereof, and the like can be used, but are not limited to these.

The polyester film may be unstretched, but it is preferably stretched, and biaxially stretched is particularly preferred.

The thickness of the polyester film is preferably 5μ to 300μ.

For polyester film, antistatic agent,
It may contain stabilizers, organic lubricants, inorganic fine particles, pigments, dyes, synthetic resins, etc.

In the present invention, the polyurethane having an anionic group that uses filtrate as a medium refers to Japanese Patent Publication No. 42-24194,
No. 6-7720, Special Publication No. 46-10193, Special Publication No. 1
19-57B59, JP 50-125197, JP 53-126058, JP 54-138098
A publicly known polyurethane such as No. 1, or a polyurethane similar thereto can be used.

The main components of the polyurethane-forming component are polyincyanate, polyol, chain extender, crosslinking agent, and the like.

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

Examples of polyols include polyethers such as polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol, polyesters such as polyethylene adipate, polyethylene-butylene adipate, and polycaprolactone, acrylic polyols, and 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
．． Examples include 4'-diaminodiphenylmethane, 4,4'-diaminodicyclohexylmethane, and water.

Polyurethane having an anionic group is a polyurethane forming component such as a polyol, a polyisocyanate compound,
A method of using a compound having an anionic group as a chain extender, etc. A method of reacting an unreacted incyanate group of the produced polyurethane with a compound having an anionic group, A method of reacting a group having an active hydrogen of polyurethane with a specific compound It can be manufactured using a method such as

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

In the method of reacting an unreacted isocyanate group of polyurethane with a compound having an anionic group, for example, bisulfite, aminosulfonic acid and its salts, aminocarbo/acid and its salts, amino alcohol sulfuric ester and its salts, Hydroxyacetic acid and its salts can be used.

In the method of reacting a group having active hydrogen of polyurethane with a specific compound, for example, dicarboxylic acid anhydride,
Salt type groups or groups capable of forming salts after ring opening, such as tetracarboxylic anhydride, sultone, lactone, ethoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isatoic anhydride, hostone, carbyl sulfate, etc. A cyclic compound having a 3- to 7-membered ring can be used.

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

The 7-ionic group in polyurethane is -BOIHl-0E
I(), H, -000)1 and their ammonium, lithium, sodium, potassium, or magnesium salts. 'The amount of anionic groups in the polyurethane is preferably from 0.5% to 8% by weight. If the amount of anionic groups is small, the water solubility or water dispersibility of the polyurethane resin is poor, and if the amount of anionic groups is large, the water resistance of the undercoat layer after coating may be poor or moisture absorption may occur. This is because the films are more likely to be rC-adhered to each other.

Even if polyurethane has good adhesion to printing inks, it has poor applicability and adhesion to polyester films, which may cause practical problems. There is also a method of using agents,
Surfactants may cause so-called blooming, resulting in stickiness and reduced adhesion, which may be undesirable.

In such cases, regardless of the adhesion and fixation properties of the printing ink, the coating properties on the polyester film,
Adhesion of printing ink to polyurethane with good adhesion of printing ink with polyurethane with good adhesion? There is a way to mix it within a range that does not cause any harm. Furthermore, a preferred method for improving the applicability and adhesion of polyurethane to a polyester film is to blend a polyester having a sulfonic acid group in water as a medium into the polyurethane coating agent of the present invention. As this polyester,
No. 73, JP-A-50-B5497, JP-A-50-12
1336, JP-A-52-155640, etc., or polyesters similar thereto can be used.

For example, dicarboxylic acid components of polyester include terephthalic acid, inphthalic acid,
2,6-7tale dicarboxylic acids and their ester-forming derivatives are used; examples of aliphatic dicarboxylic acids include nasipic acid, azelaic acid, sebacic acid and their ester-forming derivatives; Examples of carboxylic acids include oxybenzoic acid and its ester-forming derivatives.

Further, as the glycol component of the polyester, aliphatic, alicyclic, aromatic diols, etc. can be used, and examples thereof include ethylene glycol, 1°4-butanediol, diethylene glycol, triethylene glycol, 1.4-
Cyclohexane dimetatool, arxylene diol, etc. are used, and examples of poly(oxyalkylene) glycols include so-called polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.

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

Polyesters having sulfonate groups can be produced using compounds having sulfo/acid groups which together with the polyester-forming components described above form one polyester component.

Examples of compounds having a sulfonic acid group include sulfoisophthalic acid, sulfoterephthalic acid, sulfonaphthalene-
There are metal salts such as 2,6-dicarboxylic acids and their ester-forming derivatives.

Preferred metals for the metal salt include lithium, sodium, potassium, and magnesium. Among these, highly preferred compounds are 5-sodiosulfoisophthalic acid or 5-sodiosulfodimethylisophthalate.

Another method for introducing sulfonic acid groups into polyester is to sulfonate the unsaturated groups of polyester containing an ester-forming aliphatic unsaturated compound as a copolymerization component with a sulfonating agent such as sodium bisulfite or sodium metabisulfite. Methods can also be exemplified.

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 its adhesion.

The sulfonic acid group in the polyester resin needs to be present in an amount necessary to make the resin water-soluble or water-dispersible. It is preferable to use within the range.

If the amount of sulfonic acid base is less than 2 mol 5, the water solubility or water dispersibility is insufficient], and if the amount of sulfonic acid base is more than 20 mol 5, the water resistance of the undercoat layer after coating will be poor, and moisture absorption will result. This is because the films tend to adhere to each other.

Furthermore, polyester resins include not only saturated linear polyesters made from the above-mentioned ester-forming components, but also 3
A polyester made of a compound having an ester-forming component having a higher value than the polyester or a polyester having a reactive unsaturated group can also be used.

When this polyester having a sulfonic acid group is blended with the polyurethane of the present invention, the solid deafness content is 3 to 50 parts, more preferably 5 parts to 100 parts of the polyurethane.
~30 copies.

If the amount of polyester is more than 50 parts, the printing ink adhesion of polyurethane tends to not be exhibited, and if the amount of polyester is less than 3 parts, the effect of polyester on improving coatability and adhesion is unclear. There are cases where

The method for applying the polyurethane of the present invention to a polyester film is described in "Coating Method" by Yuji Harasaki, published by Maki Shoten in 1979, using a reverse roll tool,
A gravure coater, a rod coater, an air doctor coater, or a coating device other than these can be used. The coating process is performed before sequential biaxial stretching in the film forming process, before simultaneous biaxial stretching, after biaxial stretching and before stretching, after film forming and before winding, or outside the film forming process. A preferred coating method is a coating/stretching method in which a coating agent is coated on at least one side of the polyester film, and then suitably dried or stretched without drying. As a specific example of this method, a coating agent is applied to a uniaxially stretched polyester film using a roll stretching method, and the coating agent is dried appropriately or immediately stretched in a direction perpendicular to the previous stretching direction without drying, followed by heat treatment. This is the way to do it. According to this method, the coating layer can be dried simultaneously with stretching, and the thickness of the coating layer can be reduced in accordance with the stretching ratio.

The thickness of the coating layer of the biaxially stretched polyester film of the present invention is preferably in the range of 0.01μ to 1μ, more preferably in the range of α01μ to α5μ. If the thickness of the coating layer is less than 101 μm, it is difficult to apply the product uniformly, and uneven coating tends to occur on the product. If it is thicker than 1 μm, the lubricity tends to deteriorate.

The coating agent of the present invention includes methylolated or alkylolized urea-based, melamine-based, and guanamine-based crosslinking agents to improve the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer. , acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds, blocked polyisocyanates, silane coupling agents, titanium coupling agents, zirco-aluminate coupling agents, heat, peroxides, active rays, etc. It may contain reactive vinyl compounds, photosensitive resins, and the like.

In addition, the coating layer of the present invention includes inorganic fine particles such as silica, silica sol, argus, alumina sol, zirconium sol, kaolin, Merck, calcium carbonate, titanium oxide, barium salt, and carbon black to improve adhesion and lubricity. , molybdenum sulfide, antimony oxide sol, etc.

In addition, the coating agent of the present invention may optionally contain an antifoaming agent, a coating properties improver, a thickener, an antistatic agent, an organic lubricant, an organic polymer particle, an antioxidant, an ultraviolet absorber, and a foaming agent. agents, dyes,
It may also contain pigments and the like.

[Measurement and evaluation methods]

Measurement of adhesion during print-in of the present invention and evaluation criteria for effectiveness are based on the following method.

1. Types of printing ink, printing method, curing method (6) Tetron+901 white (trade name, hereinafter abbreviated as Mu-1, hereinafter the same), an air-drying ink from Jujo Kako Co., Ltd., TAPΦ9
501 White (Mu-2) was printed solidly using a Tetron 270 mesh screen and dried at room temperature for 12 hours.

CBI F, an ultraviolet curing ink from Toyo Ink Co., Ltd.
A mixture of 100 parts of D-8El indigo and 5 parts of IFD reducer (B-1) was stamped with a nylon 300 mesh screen.

Side extraction, UVl1, an ultraviolet irradiation device manufactured by Ushio Inc.
Ultraviolet curing was carried out using Type -2000 (trade name) under curing conditions of 160 W/3 and film speed of 12 m+/'min.

(100 parts of UVA-9119, an ultraviolet curing ink from Re-Seiko Advance Co., Ltd. and 4 parts of 80!-120 white.
After printing 00 parts of ink (0-1) with a nylon 500 mesh screen, UV curing was carried out in the same manner as ink B-1 except that the film speed was changed to 4-.

(9) POD, an ultraviolet curing ink from Moroboshi Ink Co., Ltd.
White T Kai (D-1), OARM Black HI) (D-2), OA
B- Ultraviolet curing was carried out in the same manner as in 1-in.

2 Add 1 square square stitches to the adhesive printing layer of printing ink, and make a width of 18.0 mm.
Use Nichiban's cellophane tape 751 to prevent air bubbles.
Apply a constant load to the length using a 3kJiJ manual load roll.

Next, fix the film and wrap one end of the cellophane tape with 5
Adhesiveness was evaluated by connecting to a weight of 001F and starting a peel test in the 30° direction of VCl after the weight naturally fell from a distance of 45 cIR.

Adhesion was evaluated using the following 5-level criteria.

4 or more is a practical range.

5: No peeling at all on the cellophane tape surface.

4: Less than 10% peels off to the cellophane tape surface. Practically speaking, if the index is 4 or more, it can be used without any problem.

3: 10 to 50% of the area peels off to the cellophane tape side.

2: 50% or more of the area peeled off to the cellophane tape side.

1: Completely peel off to the cellophane tape side.

Comparative Example 1 Biaxially stretched polyethylene terephthalate films with thicknesses of 25 μ, 50 μ, and 75 μ
1, D-1, D-2, D-5, and 'D-4 were printed using the method described above, and a peel test using cellophane tape was performed to evaluate the adhesion of the printing inks.
All the films were rated 1, meaning they were not practical as a label film.

Example 1 The same polyethylene terephthalate as in Comparative Example 1 was melt-extruded, and then a 250μ longitudinally stretched film was obtained by roll stretching. One side of this film was immediately coated with Bayer's Impranil DT, a polyurethane with sulfonic acid groups.
, 70 parts of tH (trade name) (as solid content, the same applies hereinafter)
, Dainippon Ink Industries Co., Ltd.'s Finetex ES-670 (trade name), which is a polyester having a sulfonic acid group.
A water-based coating solution containing 20 parts of alkaline melamine and 100 parts of alkyl melamine was applied, and after transverse stretching, heat treatment was performed at 230° C. to obtain a film with a thickness of 75 μm. The thickness of the coated layer of this film is α1297m"% haze is 2.1%, and the coefficient of static friction between the coated layer surface and the uncoated surface is (L55
Met. The adhesion of printing ink to the coated layer surface of this film was rated 4 for inks A-1, A-2, and D-2, B-1, ○-1, D-1, D-3, and D. -4, it was evaluated as 5, and was useful as a label film.

Example 2 The same polyethylene terephthalate as in Comparative Example 1 was melt-extruded, and then a 90μ longitudinally stretched film was obtained by roll stretching.

Immediately coat one side of this film with 5 parts of Inplanil D L 11 of Example 1 and 1 part of Finetex!
! A water-based coating solution containing 20 parts of 8-670, 10 parts of alkylol urea, and 5 parts of silica sol was applied, and after transverse stretching, heat treatment was performed at 230°C to obtain a film with a thickness of 25p. The thickness of the coating layer of this film was α10f/3, the haze was 1.6%, and the coefficient of static friction between the coating layer surface and the uncoated surface was Q, 51. The adhesion of printing ink to the coating layer surface of this film is B-1, 0-1, D-1.
It was evaluated as 5 and was useful as a label film.

Example 3 After melt-extruding the same polyethylene terephthalate as in Comparative Example 1, a longitudinally stretched film of 115 μm was obtained by roll stretching. Hytran A from Dainippon Ink Industries, a polyurethane that immediately has a carboxylic acid group on one side of this film.
A water-based coating solution consisting only of P-40 (trade name) was applied, and after horizontal stretching, heat treatment was performed at 230°C to a thickness of 5Qp.
obtained the film. The thickness of the coating layer of this film is Q,
08 t/regular 3, haze was 1.8%, and friction coefficient between the coated layer surface and the uncoated surface was α52. The adhesion of printing ink to the coating layer surface of this film is A-1, B-1.
, C-1, I)-1i, it was evaluated as 5 and was useful as a label film.

Example 4 Hytran AP- of Example 3 was used instead of the coating liquid of Example 1.
A film was prepared in the same manner as in Example 1, except that a water-based coating solution containing 80 parts of 40 (trade name) and 200 parts of Finetex II: El-670 (trade name) of Example 1 was used. Obtained.

The thickness of the coated layer of this film was 1129%, the haze was 2.0%, and the coefficient of static friction between the coated layer surface and the uncoated surface was 1L57.Printing ink on the coated layer surface of this film Adhesion was rated 4 for D-2 and A for D-2.
-1, A-2, B-1, C-1, D-1, D-3, D-
It was evaluated as 5 for A, and was useful as a label film.

Comparative Example 2 After melt-extruding polyethylene terephthalate containing 10% by weight of titanium oxide as a white pigment, a 175μ longitudinally stretched film was obtained by roll stretching. This film was further horizontally stretched and then heat treated at 230°C to obtain a film with a thickness of 50μ.

The coefficient of friction of this film was IIL32.

Printing ink adhesion to this film is B-1,0-1
, D-2, and D-3, it was evaluated as 1, and was not practical as a label film.

Example 5 The coating liquid of Example 4 was applied to the longitudinally stretched film of Comparative Example 2, and then the same procedure as in Comparative Example 2 was carried out to obtain a film having a thickness of 50 μm. This film was white and opaque, the thickness of the coated layer was (L 12 f/f1% snow, and the coefficient of static friction between the coated layer surface and the uncoated surface was (135). Printing ink adhesion was evaluated as 4 for D-2 and 1 for B-1, C-1, and D-5.
It was useful as a film for labels.

[Effects of the Invention] The label of the present invention, which is printed with a special ink and is based on a polyester film that can be obtained at a relatively low cost by a wide coating film by the coating and stretching method, has good adhesion with the printing ink. be.

Claims (1)

[Claims] 1. On at least one side of the polyester film, a coating agent containing water-based polyurethane having an anionic group as an essential component is applied, and then air-curing ink, ultraviolet curable ink, electronic A label characterized in that a printing layer is formed using any one of line-curing inks.