JP2001179912A - Easy adhesive polyestefr film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy adhesive polyester film excellent in the adhesiveness with a functional layer containing a water-soluble hydrophilic resin such as polyvinyl alcohol, polyvinyl acetal, nitrocellulose or polyoxyethylene. SOLUTION: An easy adhesive polyester film provided with an easy adhesive layer is obtained by coating at least the single surface of a polyester film before the completion of crystal orientation with an aqueous coating solution containing a resin copolymerized with polyalkylene oxide with the number of repeating units of 10-100 and applying drying, stretching and heat treatment to the coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily adhesive polyester film. More specifically, the present invention relates to an easily-adhesive polyester film having excellent adhesiveness with a functional layer containing a water-soluble / hydrophilic resin such as polyvinyl alcohol, polyvinyl acetal, nitrocellulose, and polyoxyethylene as components. is there.

[0002]

2. Description of the Related Art Polyester film has mechanical strength,
It has excellent properties such as dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and is excellent in cost performance. Therefore, it is used as a base film in various applications.
For example, a functional film in which a functional layer such as a magnetic layer or an ink layer is coated on the surface of a polyethylene terephthalate film is widely used for applications such as magnetic cards and labels.

In recent years, when laminating a functional layer on a polyester film, the use of a diluting solvent in water has been progressing mainly from the viewpoints of process safety, environmental aspects, and the like, and the functional layer itself to be coated has been conventionally used. Advanced functionality has been required. In order to meet these demands, water-soluble and hydrophilic resins such as polyvinyl alcohol, polyvinyl acetal, nitrocellulose, and polyoxyethylene have been widely used as main components of the functional layer or as components of the binder resin. Was.

On the other hand, a biaxially stretched polyester film has a low degree of surface activation due to its highly crystallized surface, and therefore has poor adhesion between the functional layer used for each application and the polyester film surface. There are drawbacks that are sufficient. In order to activate the surface of the polyester film, there is a method of physically or chemically treating the surface. However, such treatment does not provide sufficient adhesion between the polyester film and the functional layer.

[0005] A method of applying a coating layer on the surface of a polyester film using an aqueous coating agent containing an aqueous polyester resin, an aqueous acrylic resin, an aqueous urethane resin or the like to improve the adhesiveness is also widely used. I have.

However, even with these methods, the adhesiveness with a functional layer containing a water-soluble / hydrophilic resin such as polyvinyl alcohol, polyvinyl acetal, nitrocellulose, polyoxyethylene or the like is insufficient, so that problems can be solved. Not reached.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves these problems and provides a water-soluble polymer such as polyvinyl alcohol represented by a printing ink image receiving layer in ink jet printing.
Functional layer mainly composed of hydrophilic resin, water-soluble / functional layer using hydrophilic resin such as polyvinyl acetal represented by binder of various printing inks, water-soluble such as gelatin represented by photographic film An object of the present invention is to provide an easily-adhesive polyester film having excellent adhesiveness to a functional layer or the like containing a hydrophilic resin as a main component.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the problems can be solved by using a polyester film having specific physical properties as a base material, and completed the present invention. I came to.

That is, the present invention provides an aqueous coating solution containing a resin in which a polyalkylene oxide having 10 to 100 repeating units is copolymerized, on at least one side of the polyester film before the completion of the crystal orientation, and then drying. This is an easily adhesive polyester film provided with an easily adhesive layer obtained by stretching, stretching and further heat treatment.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

(Polyester) The polyester constituting the polyester film of the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

The polyester in the present invention includes, for example, polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4
-Cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalate and the like. These polyesters may be homopolymers or copolymers obtained by copolymerizing other components. Also, a mixture of these polyesters with a small proportion of another resin may be used. Of these, polyethylene terephthalate is particularly preferred. In particular, when there is a demand for a thin film and heat resistance as a base film, polyethylene-
2,6-Naphthalate is particularly preferred.

The polyester used in the present invention contains an inorganic or organic lubricant such as silicon dioxide, calcium carbonate, kaolin, or silicone particles having a particle size of 0.1 to 5 μm.
It is preferable that the content is 3 to 3.0% by weight. The lower limit of the lubricant content is more preferably 0.1% by weight, and the upper limit is more preferably 1.0% by weight.

By adding these lubricants, a polyester film having a surface center line roughness of 0.001 to 10 μm can be obtained. If the center line roughness of the film surface is less than 0.001 μm, sufficient slip properties cannot be obtained, and the film cannot be wound up,
This is not preferable because the films may adhere to each other. When the center line roughness of the surface is larger than 10 μm, a functional layer containing a water-soluble / hydrophilic resin as a main component or a component such as a binder resin (hereinafter sometimes simply referred to as “functional layer”) may be uniform. It is not preferable because it cannot be processed into

Further, the polyester used in the present invention may contain a stabilizer, a colorant, an antioxidant and other additives as required to such an extent that the original performance is not impaired.

(Polyester Film) The polyester film used in the present invention can be obtained, for example, by the following method. The polyester is melt-extruded into a film, wound around a casting drum and solidified by cooling to obtain an unstretched film. This unstretched film is
(Glass transition temperature of polyester: ° C)-(Tg + 6
0) Heat to 0 ° C. and stretch in the longitudinal direction once or twice or more so that the total magnification becomes 3 to 7 times. After that, the film is stretched at Tg to (Tg + 60) ° C. so that the width direction becomes 3 to 5 times, and then 0.1 to 10 at 200 to 250 ° C.
Heat treatment is performed for 2 seconds, and re-heat treatment is performed at a temperature lower by 10 to 20 ° C. than the heat treatment temperature while contracting or elongating 0 to 20% in the width direction to obtain a biaxially oriented polyester film.

The polyester film of the present invention comprises:
The thickness is preferably in the range of 0.5 to 500 μm. The upper limit of the film thickness is more preferably 400 μm, and the lower limit is more preferably 1 μm. However, when the polyester film is a polyethylene-2,6-naphthalate film, there is a demand for a thinner film due to, for example, recent miniaturization of printing equipment and speeding up of printing. By using a 6-naphthalate film, the thickness can be reduced to 0.5 μm, and the lower limit of the film thickness is preferably 0.5 μm. If the thickness of the film exceeds 500 μm, the production of the film becomes difficult and the productivity may be impaired. In addition, the handleability when processing the functional layer may be unfavorably deteriorated.

(Easy Adhesion Layer) In the present invention, an easy adhesion layer containing a resin in which a polyalkylene oxide is copolymerized is provided on at least one surface of the polyester film. This easy-adhesion layer is necessary for improving the adhesiveness to the functional layer using polyvinyl alcohol, polyvinyl acetal, nitrocellulose, polyoxyethylene, or the like.

The thickness of the easily adhesive layer in the present invention is 0.00
It is preferably in the range of 1 to 1 μm. The upper limit of the thickness of the easily adhesive layer is more preferably 0.5 μm, and the lower limit is more preferably 0.01 μm. By setting the thickness of the easy-adhesion layer in the above range, the adhesion between the polyester film and the easy-adhesion layer can be strengthened. As a result, it is possible to prevent troubles caused by the films sticking together when unwinding the film for processing or the like after winding and storing the film coated with the easy-adhesion layer in a roll shape.

The wetting index of the surface of the easily adhesive layer in the present invention is preferably in the range of 35 to 75 mN / m. The upper limit of the wetting index is more preferably 70 mN / m, and the lower limit is more preferably 40 mN / m. When the wetting index of the surface of the easy-adhesion layer is within the above range, the functional layer can be uniformly laminated on the easy-adhesion layer of the present invention. That is, when a coating solution containing a water-soluble / hydrophilic resin such as polyvinyl alcohol, polyvinyl acetal, nitrocellulose, or polyoxyethylene is applied to the surface of the easily adhesive layer, repelling of the coating solution can be prevented. Functional layers can be formed. Further, when the wetting index of the surface of the easily adhesive layer is in the above range, the adhesion to the functional layer is also good.

(Resin Copolymerized with Polyalkylene Oxide) In the present invention, the easy-adhesion layer contains, as a constituent, a resin copolymerized with a polyalkylene oxide. Examples of the polyalkylene oxide component include polymethylene oxide, polyethylene oxide, polypropylene oxide, polybutylene oxide and the like. The polyalkylene oxide component has a repeating unit number of 10 to 100. When the number of repeating units is less than 10, for example, the adhesiveness to a functional layer such as an ink layer becomes insufficient, and when it exceeds 100, the heat resistance of the easily adhesive layer becomes insufficient, and for example, overprinting or the like of the ink layer during printing. Inconvenience occurs.

The polyalkylene oxide component in the present invention may be a single monomer structure repeating,
Alternatively, it may be a random copolymerization component or a block copolymerization component of alkylene oxide obtained from a plurality of monomers.

The copolymerization ratio of the polyalkylene oxide component in the resin in which the polyalkylene oxide is copolymerized is preferably 0.1 to 50 mol%. When the copolymerization ratio is within this range, adhesion to a functional layer using polyvinyl alcohol, polyvinyl acetal, nitrocellulose, polyoxyethylene, or the like becomes good. In order to further enhance the adhesive effect, the lower limit of the copolymerization ratio is more preferably 0.5 mol%, and particularly preferably 1 mol%. Further, the upper limit of the copolymerization ratio is more preferably 30 mol%, particularly preferably 10 mol%, and particularly preferably 5 mol%.

The resin with which the polyalkylene oxide is copolymerized may be any resin as long as it is a thermoplastic resin.
This is preferable because the adhesiveness between the easily adhesive layer and the functional layer can be made particularly good.

One or more resins in which the polyalkylene oxide is copolymerized can be used, and polyester resins, acrylic resins, urethane resins, and the like, and modified products thereof, such as acrylic-modified polyester resins, urethane-modified polyester resins, and acrylic-modified urethane resins, can be used. Etc. may be included.

In the present invention, an epoxy, oxazoline, melamine,
A crosslinking agent such as an isocyanate, a silane coupling agent, and a zirconium-aluminum coupling agent may be added.
Of these, epoxy is particularly preferred.

(Polyester Resin Copolymerized with Polyalkylene Oxide) The polyester resin copolymerized with the polyalkylene oxide is a copolymer composed of a polybasic acid component and a polyol component. It can be obtained by polymerization. As the polybasic acid component and the polyol component,
The following can be exemplified.

That is, as the polybasic acid component, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride,
Examples thereof include 6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and dimer acid. One or more of these polybasic acid components can be used. In addition, an unsaturated polybasic acid component such as maleic acid and itaconic acid, or a hydroxycarboxylic acid component such as p-hydroxybenzoic acid can be used in a small amount.

Examples of the polyol component include ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, and the like. be able to. One or two or more of these polyol components can be used.

(Acrylic Resin Copolymerized with Polyalkylene Oxide) The acrylic resin copolymerized with the polyalkylene oxide is a copolymer composed of an acrylic monomer component and a polyalkylene oxide component, and is, for example, acrylic acid or methacrylic acid. And the like can be obtained by introducing a polyalkylene oxide into an ester moiety such as Examples of the acrylic component include the following.

That is, the acrylic monomers include alkyl acrylates and alkyl methacrylates (the alkyl groups include methyl, ethyl, n-propyl,
Isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. Acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N, N-dialkylacrylamide, N, N-dialkylmethacrylate (where the alkyl group is a methyl group, an ethyl group, or an n-propyl group) Isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N
-Alkoxyacrylamide, N-alkoxymethacrylamide, N, N-dialkoxyacrylamide, N,
Amides such as N-dialkoxy methacrylamide (alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), N-methylolacrylamide, N-methylolmethacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, etc. Group-containing monomers; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether; and monomers such as acrylic acid and methacrylic acid. The above acrylic monomer is not limited to these. These monomers are 2
Copolymerization can be carried out using more than one species.

The following monomers can be used as other copolymer components in the acrylic resin in which the polyalkylene oxide is copolymerized. That is, itaconic acid,
Monomers containing a carboxy group or a salt thereof such as maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); maleic anhydride, itacone anhydride Monomers of acid anhydrides such as acids; vinyl isocyanates,
Allyl isocyanate, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl trialkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, alkyl itaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, Examples include monomers such as ethylene, propylene, vinyl chloride, vinyl acetate, and butadiene.

(Coating of Easy Adhesion Layer) In the present invention, an aqueous solution containing a resin in which a polyalkylene oxide having 10 to 100 repeating units is copolymerized is provided on at least one surface of the polyester film before the crystal orientation is completed. (Water-dispersible or water-soluble) After applying the coating solution, the coating is dried, stretched, and further subjected to a heat treatment to form an easily adhesive layer.

The polyester film before the completion of the above crystal orientation is an unstretched polyester film, a uniaxially stretched polyester film or a stretchable biaxially stretched polyester film. Among these, a uniaxially stretched polyester film is preferable, and a longitudinally stretched polyester film uniaxially stretched in the film extrusion direction (longitudinal direction) is particularly preferable.

As long as the polyalkylene oxide does not affect the copolymerized resin or other additives,
It may contain some organic solvents. This coating liquid can be used by adding a required amount of a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant.

As such surfactants, those which can lower the surface tension of the aqueous coating liquid to 40 mN / m or less and promote the wetting of the polyester film are preferable. For example, polyoxyethylene-fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid Esters, fatty acid metal soaps, alkyl sulfates, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chloride salts, alkylamine hydrochlorides, betaine surfactants and the like can be mentioned. Further, other additives such as an antistatic agent, an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, and an antiblocking agent can be used in combination as long as the effects of the present invention are not lost.

This coating liquid is preferably applied to one or both sides of the polyester film before the crystal orientation is completed in the polyester film production process. Coating may be performed separately from the polyester film manufacturing process, but in this case, dust, dust, etc. are easily entangled, the portion becomes a defect at the time of printing, a clean atmosphere is desirable, and a suitable film is relatively inexpensive. From these points, coating during the manufacturing process is preferred. At that time, the solid content concentration of the coating solution is usually 0.1 to 30% by weight, more preferably 1 to 10% by weight.
% By weight. The coating amount is preferably 0.5 to 50 g per 1 m ^{2 of the} running film.

A known method can be applied as a coating method. For example, roll coating, gravure coating, roll brushing, spray coating, air knife,
An impregnation method, a curtain coating method, or the like may be applied alone or in combination.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Each characteristic value was measured by the following method.

(1) Film Thickness The weight of the film is measured and calculated from the density of the polyester.

(2) Thickness of Easy Adhesion Layer The thickness is calculated from the amount of the coating solution applied per 1 m ² and the solid content concentration.

(3) Wetting index The surface of the easy-adhesion layer was measured at 23 ° C. and 50% RH according to JIS K 6768 method. H. Was measured under the following conditions.
That is, formamide and ethylene glycol monoethyl ether are each mixed at a predetermined ratio, prepared at intervals of 1 mN / m, and a small amount of a dye having a high degree of coloring is added.
A standard solution was used. Absorbent cotton (15-
20 mg) is evenly wound around a length of 15 to 20 mm,
This is sufficiently immersed so that the above-mentioned standard solution does not drip, and a cotton swab is horizontally applied to the sample, moved in one direction, and applied. The applied liquid film should be as wide as possible, its area should be 6 cm ² , and the application should be completed in 0.5 seconds.

(4) Adhesiveness / Adhesiveness 1 A resin layer containing a hydrophilic resin as a main component was formed on the surface of the easily adhesive layer of the film to prepare a laminated film. The resin layer is coated with a coating solution (polyvinyl acetal 6% by weight, caborne black 2% by weight, water 80% by weight, isopropyl alcohol 12% by weight) adjusted to a dry thickness of 2 μm on the surface of the easy-adhesion layer, and heated at 100 ° C. The coating was performed by heating for 2 minutes and drying. A cellophane tape (Nichiban, 18 mm width) was attached to the surface of the resin layer, and the state of peeling when the film was rapidly peeled was visually observed, and judged according to the following criteria. Peeling less than 5%: ○ (good) Peeling 5% or more, less than 50%: Δ (normal) Peeling 50% or more: × (poor)

Adhesiveness 2 A resin layer containing a hydrophilic resin as a main component was formed on the surface of the easily adhesive layer of the film to prepare a laminated film. The resin layer was applied by applying a coating solution (10% by weight of polyvinyl acetal, 90% by weight of water) to the surface of the easy-adhesion layer so as to have a dry thickness of 10 μm, heating at 100 ° C. for 4 minutes, and drying. Further, a black solid print (15 cm × 15 cm area) was applied to the surface of the resin layer by an ink jet printer (HP DeskJet 710C), and a cellophane tape (18 mm wide made of Nichiban) was adhered to the surface, and the peeling state when rapidly peeled was visually observed. Observe and judge according to the following criteria. Peeling less than 5%: ○ (good) Peeling 5% or more, less than 50%: Δ (normal) Peeling 50% or more: × (poor)

(5) Glass transition temperature (Tg) A sample (10 mg) was set in a DSC (differential scanning calorimeter) manufactured by Perkin Elmer Co., Ltd., melted at 300 ° C. for 5 minutes, and quenched in liquid nitrogen. 10% /
The temperature is raised in minutes and the glass transition temperature (Tg) is measured.

[Examples 1 to 6 and Comparative Examples 1 to 3] 25
Intrinsic viscosity 0.6 measured in o-chlorophenol at 0 ° C.
1 polyethylene terephthalate (containing lubricant, Tg = 7)
8 ° C) from a T-die at 280-300 ° C
And on a rotating cooling drum maintained at about 30 ° C.
It was quenched while applying static electricity to obtain an unstretched film. Then
The unstretched film is stretched 3.6 times in the longitudinal direction at 105 ° C.
The film was stretched to obtain a uniaxially stretched film. This uniaxially stretched film
A coating liquid having a solid content of 3% by weight and having the composition shown in Table 1
4g / m by kiss coat method ^TwoCoated. Then 120 ° C
And stretched 3.8 times in the width direction at a fixed length at 220 ° C.
Perform processing and shrink at 210 ° C while shrinking 2% in the width direction.
Biaxial with a thickness of 100 μm, heat-treated and laminated with an easy adhesion layer
An oriented polyester film was obtained. Physical properties of this film
Are shown in Table 1.

Comparative Example 4 A biaxially oriented polyester film was obtained by forming a film in the same manner as in the example except that the easy adhesion layer was not applied. Table 1 shows the physical properties of this film.

[0048]

[Table 1]

The composition of the resin shown in Table 1 is as follows. Polyester A: 35 mol% of terephthalic acid / 11 mol% of isophthalic acid / 5 mol% of 5-sodium sulfoisophthalic acid / 45 mol% of ethylene glycol / 4 mol% of diethylene glycol / 1 mol% of polyethylene glycol (number of repeating units n = 23) It is configured. Polyester B: 35 mol% of terephthalic acid / 11 mol% of isophthalic acid / 5 mol% of 5-sodium sulfoisophthalic acid / 45 mol% of ethylene glycol / 5 mol% of diethylene glycol Acrylic A is composed of 75 mol% of methyl methacrylate / 18 mol% of ethyl acrylate / 4 mol% of N-methylolacrylamide / 3 mol% of methacrylate polyethylene glycol (number of repeating units n = 10). Acrylic B: 75 mol% of methyl methacrylate / 21 mol% of ethyl acrylate / 4 mol% of N-methylolacrylamide. Crosslinking agent: 1,3-bis (N, N-diglycidylamine)
Cyclohexane Wetting agent: polyoxyethylene (number of repeating units n = 7)
Lauryl ether

[0050]

According to the easily adhesive film of the present invention, O
Functional layers such as HP film, label, plotter film, photographic film, photographic printing paper film, barcode label, magnetic card, graphic arts etc. are used for water soluble polyvinyl alcohol, polyvinyl acetal, nitrocellulose, polyoxyethylene etc. It is possible to provide a polyester film having good adhesiveness to all of the cases where a layer containing a hydrophilic resin as a component is used.

Continued on the front page (72) Inventor Satoshi Kitazawa 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture F-term in the Sagamihara Research Center, Teijin Limited 4F006 AA35 AB24 AB32 AB35 BA01 CA02 CA03 CA07 DA04 4F100 AK01B AK25B AK25J AK41A AK41B AK41J AK42A AK54B AK54J AL01B AR00B BA02 EH46B EJ37 GB90 JA11A JA20A JA20B JL11 JL11B JM01B YY00B

Claims (6)

[Claims] 1. A polyester film having a recurring unit number of 10 to 1 on at least one surface of a polyester film before completion of crystal orientation.
An easy-adhesion polyester film provided with an easy-adhesion layer obtained by applying an aqueous coating solution containing a resin in which the polyalkylene oxide of No. 00 is copolymerized, followed by drying, stretching, and heat treatment. 2. The easily adhesive polyester film according to claim 1, wherein the resin in which the polyalkylene oxide is copolymerized is a polyester resin or an acrylic resin. 3. The easily adhesive polyester film according to claim 1, wherein the thickness of the easily adhesive layer is in the range of 0.001 to 1 μm. 4. The wetting index of the surface of the easily adhesive layer is 35 to 75 m.
The easily adhesive polyester film according to any one of claims 1 to 3, which is in a range of N / m. 5. The easily adhesive polyester film according to claim 1, wherein the polyester constituting the polyester film contains polyethylene terephthalate as a main component. 6. The easily adhesive polyester film according to claim 1, wherein the polyester constituting the polyester film contains polyethylene-2,6-naphthalate as a main component.