JPH06115030A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To obtain a laminated polyester film superior in easy adhesion, easy lubricity, resistance to blocking and antistatic properties by a method wherein a polyester resin layer having sulfonic metal salt group is provided on one surface of a polyester film, and thereon an acrylic resin layer is laminated. CONSTITUTION:A laminated polyester film is obtained by providing a polyester resin layer having sulfonic metal salt group on at least one surface of a polyester film and thereon laminating an acrylic resin layer. The two layers are applied before the completion of the crystalline orientation of the polyester film. After the film is oriented in at least one direction, the crystalline orientation of the polyester film is completed. The sulfonic metal salt group-containing polyester is a polyester containing an ester-forming sulfonic metal salt group- containing compound as a copolymerizing component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly to a laminated polyester film having excellent adhesion, slipperiness, blocking resistance and antistatic property.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are magnetic recording materials, packaging materials, electrical insulating materials, various photographic applications, and graphic quartz because of their excellent mechanical properties, electrical properties, dimensional stability, transparency and heat resistance. It is used as a base film in many fields such as applications. However, on the other hand, 2
The axially oriented polyester film has drawbacks such as poor adhesiveness because the surface is highly crystallographically oriented and that it is easily charged with static electricity due to friction. Many proposals have been made in the past to improve this. For example, to impart adhesiveness, physical methods such as corona discharge treatment in various gas atmospheres, plasma treatment, and ultraviolet irradiation treatment, chemical treatment with alkali, trichloroacetic acid, amine, phenol, or the like, or a combination thereof is used. Treatment methods are being tried,
All of them had drawbacks such as insufficient adhesiveness and a decrease in treatment effect over time.

On the other hand, an easy-adhesion treatment by providing a primer layer on the surface of a polyester film has been actively performed in recent years, and in particular, a method (in-line coating method) of performing the primer treatment at a stretch in the polyester film manufacturing process. It is considered to be influential in terms of process simplification, manufacturing cost, environmental protection, etc. As a primer layer used for this purpose, an organic sulfonate group-containing polyester resin (Japanese Patent Laid-Open No. 58-1727) for the purpose of easy adhesion, a mixture of an organic sulfonate group-containing polyester resin and an anionic urethane resin (special Kaisho 58-78761
No. gazette), etc. Further, a specific acrylic resin is applied and stretched for the purpose of imparting slipperiness.
-204241 and JP-A-61-204242). Further, there is a coating (JP-A-58-124651) coated with a mixture of a sulfonate group-containing polyester resin and an acrylic resin which is dissolved or dispersed in water for the purpose of achieving both easy adhesion and easy slipperiness.

[0004]

However, the above-mentioned conventional technique has the following problems. That is, when a sulfonate group-containing polyester is used as the easy-adhesion layer, even if the desired adhesiveness is initially obtained, the easy-adhesion layer lacks moisture resistance and water resistance, and rolls under high humidity. When it is rolled and stored, it has a problem that it is easily blocked and lacks in slipperiness under high humidity. This also applies to a coating film in which urethane resin or acrylic resin is mixed.

On the other hand, a polyester film is extremely likely to be charged due to friction between the films. Further, the polyester resin layer having the sulfonate group introduced therein tends to be remarkably negatively charged by friction with the polyester film. Usually, in the process of providing another resin layer (for example, ink, magnetic paint, etc.) on the easy-adhesion layer, the film wound in a roll shape is unwound and conveyed while being in contact with the roll such as silicon or metal. However, during this process, the polyester film is easily negatively charged, and dust adhesion due to electrostatic adsorption is often a problem. Therefore, in the triboelectric charging with the polyester film, 0 to weak positive charging is preferable.

The present invention eliminates these drawbacks, has excellent adhesiveness, does not have blocking under high humidity, is 0 to weakly positively charged even when it is frictionally charged with a polyester film, and has excellent slipperiness. It provides a film.

[0007]

To achieve the above object, the present invention provides a polyester resin layer having a metal sulfonate group on at least one side of a polyester film, and an acrylic resin layer is laminated on the layer. A laminated polyester film obtained by applying the two layers before the crystal orientation of the polyester film is completed, stretching the polyester film in at least one direction, and then completing the crystal orientation of the polyester film. The main point is a laminated polyester film characterized by the following.

The polyester of the polyester film referred to in the present invention is a general term for polymers having an ester bond as the main chain of the main chain, and particularly preferred polyesters are polyethylene terephthalate, polyethylene 2,6.
Naphthalate, polybutylene terephthalate, and the like. Among these, polyethylene terephthalate is most preferable in view of quality, economy and the like. Therefore, hereinafter, polyethylene terephthalate (hereinafter polyethylene terephthalate is abbreviated as PET) will be described as a typical example of polyester.

PET is 80 mol% or more, preferably 9
Although 0 mol% or more contains ethylene terephthalate as a repeating unit, other dicarboxylic acid components and diol components may be copolymerized within this limited range. Also this P
Known additives in ET, such as heat resistance stabilizers, oxidation resistance stabilizers, weather resistance stabilizers, UV absorbers, organic slip agents, pigments,
Dyes, organic or inorganic fine particles, antistatic agents, nucleating agents and the like may be added. Intrinsic viscosity of PET (25 ℃
(Measured in ortho-chlorophenol) of 0.40-1.
20 dl / g, preferably 0.50 to 0.80 dl / g
Those within the range are suitable for the content of the present invention.

The PET film using the above PET is biaxially oriented when the coating layers are laminated, and the biaxially oriented PET film is an unstretched P film.
The ET sheet or film is stretched about 2.5 to 5.0 times in the longitudinal direction and the width direction, respectively, and then 150 times.
It is a product which has been subjected to heat treatment at ˜250 ° C. to complete the crystal orientation, and which exhibits a biaxial orientation pattern by wide-angle X-ray diffraction. The thickness of the PET film is not particularly limited and is appropriately selected depending on the application.

The present invention is characterized in that two different types of resin layers are laminated on the same side of the PET film.
That is, a polyester resin layer having a metal sulfonate group is provided as the first layer, and an acrylic resin layer is laminated on the layer.

The term "polyester containing a metal sulfonate group" as used herein means a polyester having a compound containing a metal sulfonate group that forms an ester as a copolymerization component.
Examples of the ester-forming sulfonic acid metal base-containing compound include alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,6-dicarboxylic acid, And ester-forming derivatives thereof. Of these, the sodium salt of 5-sulfoisophthalic acid is preferable from the viewpoint of adhesion to the PET film. The copolymerization amount of the ester-forming metal sulfonate-containing compound is 5 to 30 mol%, preferably 8 to 20 mol%, and more preferably 10 to 15 mol% of the total dicarboxylic acid component with the PET film. It is desirable in terms of adhesion and solubility in hot water.

As other compositions to be copolymerized with the ester-forming metal sulfonate-containing compound, various dicarboxylic acids, their ester-forming derivatives, and diol can be mentioned. Dicarboxylic acids and their ester-forming derivatives include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids and their ester-forming derivatives. Specific examples include terephthalic acid, isophthalic acid and phthalic acid. Acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-
Examples thereof include naphthalenedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, hexahydroterephthalic acid, ε-oxycaproic acid, trimellitic acid, trimesic acid, pyromellitic acid, and ester-forming derivatives thereof. Also, as the diol component, ethylene glycol,
Propylene Glycol, Butylene Glycol, Hexamethylene Glycol, Neopentyl Glycol, 1,1-
Cyclohexane dimethanol, 1,4-cyclohexane dimethanol, diethylene glycol, triethylene glycol, pentaerythritol, trimethylolpropane, polyethylene glycol, polytetramethylene glycol, etc. be able to. These acid components,
The diol component may be copolymerized in an arbitrary ratio, but terephthalic acid is used as the acid component in view of handling of the polymer.
It is desirable that the amount is 0 mol% or more, preferably 65 mol% or more, and more preferably 75 mol% or more. Further, those having the above-mentioned polyester as a skeleton and having an acrylic monomer graft-copolymerized on the side chain can also be used.

Next, the acrylic resin layer provided on the polyester resin layer containing a metal sulfonate group will be described.
As the acrylic resin used in the present invention, various copolymers produced by a known method can be used, but those having at least one or more crosslinkable functional groups in the polymer structure are preferably those having blocking resistance and easy It is preferable in terms of lubricity. Alkyl acrylate and alkyl methacrylate as the monomer component constituting the acrylic resin (as the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl Group, a 2-ethylhexyl group, a lauryl group, a stearyl group, a cyclohexyl group, etc.) as a basic skeleton, and those copolymerized with the following monomers to provide a crosslinkable functional group are preferable. Examples of such a functional group include a carboxyl group, a methylol group, an acid anhydride group, a sulfonic acid group, an amide group or a methylolated amide group, an amino group (including a substituted amino group), or an alkyl group. Examples of the modified amino group, hydroxyl group, epoxy group and the like. Examples of the monomer having the above functional group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinylsulfonic acid, styrenesulfonic acid, acrylamide, methacrylamide, N-methylmethacrylamide, and methylolation. Acrylamide, methylated methacrylamide, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate And those obtained by methylating the above amino group, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β -Hydroxy vinyl ether, 5-hydroxy pen Chill vinyl ether, 6
-Hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, glycidyl acrylate, glycidyl methacrylate and the like can be mentioned, but not limited thereto. Absent. In addition to the above compounds, the following compounds, for example, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, mono- or dialkyl esters of maleic acid and itaconic acid, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine. , Vinylpyrrolidone,
Alkoxysilane having a vinyl group may be used as a copolymerization component.

The acrylic resin used in the present invention may be obtained by copolymerizing a monomer forming the above-mentioned basic skeleton and a monomer having a crosslinkable functional group in an arbitrary ratio, but the effect of the present invention is more remarkably exhibited. It is desirable that the glass transition point of the acrylic resin is 20 ° C. or higher, preferably 40 ° C. or higher, and the molecular weight is 100,000 or higher, preferably 300,000 or higher. Further, a crosslinking agent that reacts with a functional group other than heat for the purpose of crosslinking the crosslinkable functional group, for example, a melamine resin,
It is more preferable to add a polymer having an isocyanate group.

In the present invention, the acrylic resin layer may be a smooth uniform coating film, but it is particularly preferable because the effect of the present invention can be more remarkably exhibited by forming fine projections on the surface by the acrylic resin layer. . Such protrusions can be developed by applying an acrylic resin having a crosslinkable functional group or a coating agent in which a crosslinker is used in combination to a polyester film, drying it, and stretching it in at least one direction. The acrylic resin is preferably an aqueous dispersion, and the average particle size of the resin is 5 nm to 500.
Those of nm can be preferably used.

The laminated thickness of the above two layers is not particularly limited, but usually the polyester resin layer is 0.01 to 0.5 μm.
m, preferably 0.05 to 0.2 μm. In addition, the acrylic resin layer has a thickness of 0.003 to 0.1 μ from the viewpoint of forming protrusions.
m, preferably 0.007 to 0.05 μm.

In the present invention, the coating film is produced by a method of applying before the crystal orientation of the polyester film of the substrate is completed, then stretching in at least one direction, and then completing the crystal orientation of the PET film. It is something. That is, one or both sides of a base PET film that has not been stretched or has been stretched in the longitudinal direction is subjected to corona discharge treatment, and an aqueous liquid of a polyester resin having a metal sulfonate group as the first layer is applied. Then apply 120
After drying at a temperature of ℃ or less, if necessary, corona discharge treatment is performed, and the water dispersion of the acrylic resin of the second layer is applied. 80 to 1 while gripping with clips continuously after application
After being introduced into a hot air zone of 30 ° C. and dried, or while being dried, it is stretched in the width direction, and further introduced into a hot air zone of 160 to 250 ° C., and heat treated for about 1 to 30 seconds to complete the crystal orientation. Is the way. Further, after the stretching in the width direction and before the heat treatment, by further stretching by 1.1 to 1.8 times in the longitudinal direction, the protrusions on the surface become more visible, and the slipperiness and blocking resistance are improved. Therefore, it is preferable. By using this method, the adhesiveness to the base PET film and the fine projections of the acrylic resin layer are formed, and the object of the present invention can be achieved more effectively. In the case of a method other than the above method, for example, when the above-mentioned two layers are laminated on a biaxially oriented PET film by a usual coating method, the adhesion to the base film or the adhesion between the first layer and the second layer is insufficient. Or, it becomes insufficient in terms of blocking resistance and slipperiness.

The shape and density of the protrusions are not particularly limited, but the average protrusion diameter (average length of the protrusions in the longitudinal direction and the width direction) is 0.001 to 1 μm, preferably 0.005.
It is preferably 0.2 μm. Protrusion density is 1 × 10 ⁵
Pieces / mm ² or more, preferably 1 × 10 ⁶ / mm ² or more,
More preferably, it is 1 × 10 ⁷ pieces / mm ² or more in terms of slipperiness of the surface. Height of protrusion is 0.001μ
m to 0.5 μm, preferably 0.002 μm to 0.2 μm
It is preferably m.

The first layer (polyester resin layer having a metal sulfonate group) and the second layer (acrylic resin layer)
In the known additives in the range that does not impair the effects of the present invention, for example, heat resistance stabilizer, oxidation resistance stabilizer, weather resistance stabilizer,
UV absorbers, organic lubricants such as waxes, organic,
Inorganic fine particles, antistatic agents, cross-linking agents and the like may be added. In particular, addition of a cross-linking agent to the acrylic resin layer is preferable from the viewpoint of forming protrusions. Specific examples of the cross-linking agent include methylolated or alkylated urea-based, melamine-based, acrylamide-based, polyamide-based, epoxy compounds, blocked isocyanate compounds and the like. The coating method is a known coating method such as a river coat method, a gravure coat method, a rod coat method, or a die coat method.
Any method such as the G method can be used.

Next, an example of the method for producing the laminated polyester film of the present invention will be described, but the present invention is not limited to this. The pellets of PET, which are substantially free of particles, are thoroughly vacuum dried and then fed to the extruder to about 2
Sheets are melt-extruded at 80 ° C. and cooled and solidified to prepare unstretched PET sheets. 80-120 this sheet
A uniaxially oriented PET film is obtained by stretching the film in the longitudinal direction by 2.5 to 5 times with a roll heated to ℃. A corona discharge treatment is applied to one side of this film, and an aqueous solution of a metal sulfonate-containing polyester resin diluted to a predetermined concentration is applied.
After coating, it is continuously introduced into a hot air zone heated to 80 to 120 ° C. to sufficiently dry and remove water. Corona discharge treatment is applied to the coated surface of the film, if necessary, and an aqueous dispersion of acrylic resin diluted to a predetermined concentration is coated. After coating, the end portion of the film is gripped with a clip and introduced into a hot air zone heated to 80 to 140 ° C. and stretched 2.5 to 5.0 times in the width direction. Subsequently, it is introduced into a heat treatment zone of 160 ° C. to 240 ° C. and heat treatment is performed for 1 to 10 seconds to complete the crystal orientation. In this heat treatment step, a relaxation treatment of 3 to 12% may be performed in the width direction or the longitudinal direction, if necessary.

The laminated polyester film thus obtained has excellent adhesiveness, slipperiness, and antistatic properties, and can be suitably used for base films for magnetic recording materials, for photography, for plate making and the like.

[0023]

[Characteristic Measuring Method and Effect Evaluation Method] The characteristic measuring method and effect evaluating method in the present invention are as follows.

(1) Thickness of coating layer The thickness was determined from a photograph of the cross section of the coating layer of the laminated film, which was observed using a transmission electron microscope HU-12 manufactured by Hitachi, Ltd.
The thickness was an average value in the measurement visual field, and was an average value of 30 pieces.

(2) Sliding property The coated surfaces are overlapped with each other, and ASTM-D-1894-63 is used.
The coefficient of static friction and the coefficient of dynamic friction were measured according to.

(3) Charging Properties 10 layers of PET film having no coating layer and having a thickness of 50 μm were wound around a metal drum, and the laminated surface of the laminated polyester film was contact rubbed for 5 seconds while rotating 1000 times for 1 minute. At this time, a load of 250 g was applied to one end of the laminated film. After 5 seconds of contact friction, the laminated film was released from the drum, and immediately the potential accumulated on the laminated surface was measured by an electrostatic meter.

(4) Adhesiveness-1 (Adhesion between base film and laminated film) 100 1mm ² crosscuts were put in the laminated film, and cellophane tape manufactured by Nichiban Co., Ltd. was stuck on it with a finger. After strongly pressing, the film was rapidly peeled in the direction of 180 degrees, and the number of remaining films was judged.

(5) Adhesiveness-2 (adhesiveness of magnetic paint) Daiferacoat CAD4301 (Dainichi Seika Kogyo Co., Ltd.)
(Made by Sumitomo Bayer Co., Ltd.) to 100 parts by weight to prepare a coating material having a solid content concentration of 20% by weight, and using a bar coater, the thickness after drying is About 5
It was applied to have a thickness of μm and dried at 100 ° C. for 5 minutes.
Adhesiveness was determined by the same method as in (4) above.

(6) Blocking resistance The laminated film surfaces of the laminated polyester film are 3 cm × 4.
After overlapping in an area of cm and applying a load of 500 g / 12 cm ² for 24 hours in 50 ° C. 85% RH, the shear peel stress of the overlapped portion was measured at a tensile speed of 200 mm / min.

(7) Number, Shape, and Height of Protrusions Using a scanning electron microscope DS-130 manufactured by Akashi Seisakusho, photographs were taken at a magnification of 1 to 30,000 and the number of protrusions of particles was counted. The shape (diameter) of the protrusion was actually measured from the photograph, and the average value of 100 measurements was taken. The protrusion height was measured using a non-contact three-dimensional fine shape measuring machine ET-10HK type manufactured by Kosaka Seisakusho, and set as an average value of 30 measurement points.

[0031]

EXAMPLES Next, the present invention will be explained based on examples, but the present invention is not necessarily limited to these.

Example 1 PET substantially free of particles (intrinsic viscosity 0.65 dl
/ G) Pellets were sufficiently dried in vacuum and then fed to a heated extruder at 280 ° C. and extruded in a sheet form from a T-shaped die. The sheet was wound around a mirror-finished drum having a surface temperature of 50 ° C. and cooled and solidified to prepare an unstretched PET film. This PET film was stretched 3.5 times in the longitudinal direction while passing through a group of heating rolls at 95 ° C. to obtain a uniaxially oriented film. A corona discharge treatment was applied to one surface of this film, and the solution A shown below was applied so that the laminated thickness would be 0.05 μm after the completion of the crystal orientation. After coating, it is continuously dried with hot air at 85 ° C. to sufficiently remove water, and then the dried surface of the solution A is subjected to corona discharge treatment so that the layer thickness becomes 0.01 μm after completion of crystal orientation of solution B below. Was applied to. After coating, while continuously gripping the edges with clips, introduce it into a heating zone of 110 ° C and dry it, and after stretching it by 4.0 times in the width direction after remaining heat, further heat treatment for 3 seconds with a heating zone of 225 ° C. The base material PET film has a thickness of 10 μm, and the laminated thickness is A / B: 0.05 / 0.01 μm.
An axially oriented PET film was obtained.

"A liquid composition" terephthalic acid / 5-sodium isophthalic acid / ethylene glycol (85/15/1
(00 mol%) of the polyester copolymer dissolved in hot water at 90 ° C. with stirring to obtain a solid content of 2.0% by weight.
A coating solution of was prepared.

"B liquid composition" Aqueous dispersion of acrylic copolymer comprising methyl methacrylate / ethyl acrylate / acrylic acid / N-methyl acrylamide (62/35/2/1% by weight) was diluted with water. And solid content concentration of 0.5% by weight
A coating solution of was prepared.

As shown in Table 1, the laminated polyester film obtained as described above had good adhesiveness, slipperiness, blocking resistance and charging characteristics.

Comparative Example 1 In the same manner as in Example 1, a laminated polyester film coated with only the liquid A was prepared. This laminated polyester film was highly charged on the negative side, and had insufficient blocking resistance and slipperiness.

Comparative Example 2 In the same manner as in Example 1, a laminated polyester film coated with only the liquid B was prepared. This laminated polyester film was highly charged on the positive side.

Comparative Example 3 In Example 1, a polyester film having no laminated film was prepared. This film had no adhesion to the topcoat paint and was extremely inferior in slipperiness.

Comparative Example 4 A biaxially oriented PET film having no laminated film was subjected to corona discharge treatment on one side thereof, and the solution A of Example 1 was applied to the coated film. After drying at 120 ° C. for 3 minutes, the solution B of Example 1 was applied. It was dried at 120 ° C. for 3 minutes to prepare a laminated polyester film. This laminated polyester film had insufficient adhesion to the overcoat layer and lacked in slipperiness.

Comparative Example 5 In the same manner as in Example 1, the laminated polyester film was prepared by laminating the liquids A and B in reverse. Although this film had excellent adhesion to the overcoat layer, it had poor slipperiness and blocking resistance.

Example 2 Solution B of Example 1 was added with 10% by weight based on the solid content of acrylic resin.
Example 1 was added with the hexamethylolated melamine resin of
A laminated polyester film was prepared in the same manner as in. This film had excellent characteristics as shown in Table 2 in which extremely fine projections were formed on the surface.

Example 3 In Example 1, after stretching in the width direction, the film was further stretched in the longitudinal direction by 10
After stretching 1.3 times by a roll group at 0 ° C.,
It heat-processed and the laminated polyester film was created. Very fine protrusions were formed on the laminated surface of this film, and as shown in Table 2, excellent properties were exhibited.

[0043]

[Table 1]

[Table 2]

[0044]

Industrial Applicability The present invention is a laminated polyester film in which a polyester resin layer having a metal sulfonate group is provided on at least one side of a polyester film, and an acrylic resin layer is laminated on the layer. Is obtained by applying the polyester before the crystal orientation is completed, stretching it in at least one direction, and then completing the crystal orientation, and has the following excellent effects.

(1) In triboelectrification with PET, it becomes 0 to weakly positively charged, and is less likely to be charged as compared with the conventional one coated with a sulfonic acid metal group-containing polyester or an acrylic resin. Therefore, dust is attached in the step of applying the overcoat layer. There are few obstacles due to static electricity such as or solvent ignition.

(2) Excellent adhesion to the base film and the magnetic coating of the overcoat layer.

(3) Excellent in slipperiness and good blocking resistance under high humidity.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08J 7/04 CFD // B29K 67:00 4F B29L 9:00 4F

Claims (3)

[Claims] 1. A laminated polyester film in which a polyester resin layer having a metal sulfonate group is provided on at least one surface of a polyester film, and an acrylic resin layer is laminated on the polyester resin layer, wherein the two layers are polyester films. The laminated polyester film is obtained by coating the polyester film before completion of the crystal orientation, stretching in at least one direction, and then completing the crystal orientation of the polyester film. 2. The laminated polyester film according to claim 1, wherein the acrylic resin layer is a layer having fine protrusions. 3. The laminated polyester film according to claim 1, wherein the acrylic resin layer is a layer formed of an acrylic resin having a crosslinkable functional group.