JPH01289838A - Multi-layered film - Google Patents

Abstract

PURPOSE:To obtain a multi-layered film excellent in double transfer, flatness and easy adhesion of a toner by providing a specified surface layer and a specified coating layer on at least either surface of a polyester film and orienting it. CONSTITUTION:A pelletized polyester having sulfonic acid (salt) groups, desirably, a polymer of formula I (wherein X is H, K or the like) is melt-extruded into an unoriented sheet, which is optionally oriented. A mixed resin of 5-60wt.% polymer mainly consisting of repeating units of formula II [wherein R is H or CH3, M is H, an alkali (alkaline earth) metal or NH4, R<1-4> are each H, a halogen, an alkyl or an anlkoxyl] with a water-soluble or water-dipsersible resin and inert inorganic particles of a mean particle diameter of 0.08-2.0mum are applied to at least either surface of the sheet. The resulting sheet is biaxially oriented to obtain a multi-layered film wherein the concentration of the sulfonic acid (salt) groups on the surface layer is 0.002-2.0%, the thermal shrinkage at 150 deg.C in both the machine direction and the crosswise direction at 150 deg.C is 1.0% or below, and the coating layer comprises the polymer of formula II and said inorganic particles, and the ratio of the mean particle diameter of the inorganic particles to the thickness of the coating layer is 1.1-80.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a biaxially stretched polyester film that is excellent in multi-feedability, flatness, and easy toner adhesion.

[Prior Art] Conventionally, the following methods have been known as methods for imparting transparency, single-layer feedability, flatness, and easy toner adhesion.

That is, Japanese Patent Application Laid-Open No. 61-24493.

As seen in JP-A No. 60-244589, a toner-adhesive layer is provided on the film surface, or a matte layer having antistatic properties is applied as shown in JP-A-51-34734. Or, the method of JP-A-1973-! Publication No. 7071, JP-A-52-470
As seen in Publication No. 69, polyethylene glycol.

One method is to provide a toner adhesion layer on a film mixed with various surfactants such as sodium dodecylbenzenesulfonate.

[Problems to be Solved by the Invention] However, simply providing a toner-adhesive layer on the film surface will cause the film to become electrically charged and prevent it from sliding against each other.
This method has the disadvantage that more than one sheet of film is fed overlapping each other (double feeding), causing trouble.

On the other hand, when a matte layer with antistatic properties is provided, the film has excellent multi-feedability but lacks transparency, and when various surfactants are added to the base film or coating layer, toner adhesion The disadvantage is that it worsens the sex.

The present invention aims to improve these problems and provide a composite film that is excellent in transparency, double feedability, flatness, and toner adhesion.

[Means for Solving the Problems] The present invention provides a composite film in which a coating layer is provided on at least one side of a polyester film, wherein the concentration of sulfonic acid or sulfonate in the surface layer of the polyester film is 0.002 to 0.002. 2.0%, the heat shrinkage rate at 150°C of the polyester film is 1.0% or less in both the longitudinal direction and the width direction, and the coating layer has a general formula (where R is hydrogen or methyl group, M is Hydrogen, alkali metal, alkaline earth or ammonium, R+, R2,R
3 and R4 are each hydrogen, halogen, alkyl group or alkoxy group. Same below. ) consisting of a resin containing 5 to 60% by weight of a polymer whose main constituent is a repeating unit, and inert inorganic particles with an average particle size of 0.08 to 2.0 μm, d) and the thickness (T) of the coating layer
This is a composite film characterized by having a ratio (d/T) of 1.1 to 80.

The polyester in the present invention includes ethylene terephthalate, ethylene α, β-bis(2-chlorophenoxy>ethane-4,4°-dicarboxylate, ethylene α, β
The main component is at least one structural unit selected from -bis(phenoxy)ethane-4,4°-dicarboxylate and ethylene 2,6-naphthalate units.

Further, other components other than those mentioned above may be copolymerized within a range that does not impede the present invention, preferably within 10 mol%.

The film of the present invention has the above-mentioned composition as its main component, but various polymers may be blended within the range that does not impede the purpose of the present invention, and antioxidants, heat stabilizers, lubricants, ultraviolet absorbers, Inorganic or organic additives such as nucleating agents may be added to the extent that they are normally added.

In the present invention, the method of adding sulfonic acid or its salt is not particularly limited, but it is preferable to add it in the form of a polymer, preferably in the form of a polymer with a weight average molecular weight of m1ooo or more, more preferably in the form of a polymer with a weight average molecular weight of 10,000 or more. suitable. Polymers containing sulfonic acid or its salts are not particularly limited, but representative examples include acrylic acid, acrylic esters,
Examples include polymers copolymerized with methacrylic acid, methacrylic acid esters, or styrene, or consisting only of styrene, and polymers using 03X as part or all of the dicarboxylic acid of various polyesters.

However, when using a polymer introduced in such a form, the improvement effect is more remarkable, which is probably due to insufficient compatibility with the base polymer polyester, so it is preferable.

However, X is not particularly limited, but includes H+ and Na+.

K+, NHJ+, Li+, Ca+, etc. are cationic ions. Among them, from the viewpoint of thermal stability when mixed with polyester and extruded, N) lJ+, Lt+, Ca++, +
However, Li''e K+ and Ca+10 are particularly preferred.

In the present invention, the concentration in the film surface layer is set to 0.0
It is necessary to set it to 02-2.0%. Preferably 0.00
It is 6 to 0.8%, more preferably 0.102 to 0.2%. If it is less than 0.002%, the strength of the coating film will be poor, while if it exceeds 2%, the properties of the base polyester will deteriorate.

There are various methods to achieve the concentration in the film surface layer within the range of the present invention, and there are no particular limitations. Typical methods include kneading necessary additives, combining the kneaded layer with the base material, and adding the necessary additives to the base material. Mention may be made of the method of applying a layer containing additives. However, the method of kneading is simple, does not deteriorate the physical properties of the base polyester film, and has excellent coating toughness, and in particular, the method of kneading using the method described below. is excellent. That is, a compound having a sulfonic acid or a sulfonic acid salt whose melt viscosity at the melt extrusion temperature of the base film is 1/2 or less, preferably 1/3 or less, more preferably 1/8 or less of that of the base polyester. A predetermined polyester is produced using an extruder with a so-called compression ratio (ratio of polymer filling amount in the feed section and the metal ring section (cross-sectional area ratio)), which is a parameter indicating the degree of kneading of the extruder, of 3.8 or more. The time from adding the polymer to discharging it from the nozzle is 10 minutes or more, preferably 15 minutes.
It is preferable to carry out extrusion molding on a cooling drum for at least 120 minutes, followed by stretching and heat treatment. The film obtained in this way has a particularly high concentration of sulfonic acid or sulfonate in the surface layer compared to the center of the film, which increases the toughness of the coating without deteriorating the properties of the base material. This is preferable because it makes it possible to

However, in the present invention, the concentration of sulfonic acid or sulfonic acid salt in the surface layer is determined by Shimadzu X-ray photoelectron spectroscopy ESCA.
It will be expressed as the relative intensity ratio of S2p to C1s in the top 100 people using 750 under the measurement conditions shown below.

- Measurement conditions - Excitation X-ray: M gK Cr1.2 line (1253,6e
V. It is a sulfonate or a polymeric sulfonic acid. There is no limit to the rate of introduction of sulfone groups, but in view of the effect of improving conductivity and adhesiveness, the rate of introduction is preferably 40 to 100 mol %. More preferably 75 mol% to 100 mol%, even more preferably 90 mol%
It is mol% to 100 mol%. Of course, the above-compounds with pores, styrene, methacrylic acid (ester)
, acrylic acid (ester), and fumaric acid (ester) are also included in the present invention, but the compound exhibiting the above-mentioned pores accounts for 40 mol% or more, preferably 60% or more, and more preferably 90% or more. If it accounts for 100% or less, it is preferable from the viewpoint of conductivity.

The weight average molecular weight is not particularly limited, but is 1000 to 50
00,000 is preferable, more preferably 2,000 to 1,000,000,
More preferably, it is 10,000 to 500,000.

The coating layer to be provided on the base material is a mixture of a polymer whose main constituent is a repeating unit called "mona" and another resin.

Although the resin to be mixed is not particularly limited, it is preferable to mix it with a water-soluble or water-dispersible resin from the viewpoint of being able to be applied in the form of a water-based paint and from the viewpoint of dispersibility. Examples of water-soluble or water-dispersible resins include polyester resins, acrylic resins, polyamide resins, urethane resins, vinyl resins, butadiene resins, epoxy resins, silicone resins, and mixtures thereof. It can be mentioned regardless of thermosetting property.

Adhesion (blocking property) and water resistance of the coating layer.

Solvent Resistance 2 Methylolated or alkylolated urea-based crosslinking agent to improve mechanical strength.

Resins such as melamine, acrylamide, and polyamide, epoxy compounds, and aziridine compounds.

The coating layer may contain reactive compounds such as blocked polyisocyanates and vinyl compounds.

The coating layer of the present invention contains an antifoaming agent, a coating property improver, a thickener, an organic lubricant, and an antioxidant, if necessary.

The ultraviolet absorber 2 may contain a blowing agent, dye, pigment, etc.

To improve the applicability and adhesion of the coating agent to the film,
Although the film may be subjected to chemical treatment or electric discharge treatment before coating and stretching, it is not particularly necessary in the present invention because the affinity with the base film is improved.

As water-soluble or water-dispersible resins, polyurethane,
It is preferable to use polyester or alkyl resin from the viewpoint of adhesiveness and transparency. Specific examples of suitable polyurethanes include polyurethanes having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half ester group, and among these, polyurethanes in the form of ammonium salts.

A specific example of a suitable polyurethane includes 0.5 to 20 mol% of 5-sulfondium isophthalic acid.
Copolymerized polyesters can be mentioned. Among them, at least one of terephthalic acid, isophthalic acid, and adipic acid is used as an acid component, and ethylene glycol, hexane glycol, 1,4-
At least one of butanediol, diethylene glycol, neopentyl glycol, and tetramethylene glycol
It is particularly preferable to use a polyester having seeds and a viscosity of 3 to 6 cps when diluted by 5% by weight, since not only the adhesive and antistatic properties but also the surface of the composite layer are smooth and the film is excellent in gloss.

Examples of acrylic resins include those containing alkyl acrylate or alkyl methacrylate as a main component, and 30 to 99.9 mol% of this component and vinyl monomers copolymerizable with these and having a functional group. A water-soluble or water-dispersible resin containing 70 to 0.1 mol% of polymeric components is preferred.

Vinyl monomers that can be copolymerized with alkyl acrylate or alkyl methacrylate and have a functional group impart hydrophilicity to the resin and improve the water dispersibility of the resin.
Alternatively, it is preferable to have a functional group that improves the adhesion between the resin and the polyester film or other coating layer provided on the undercoat layer, and the preferable functional group is a carboxyl group or a salt thereof, a 2M anhydride group, or a sulfone Acid group or its salt, amide group or alkylolated amide group.

These include amino groups (including substituted amino groups), alkylolated amine groups, salts thereof, hydroxyl groups, epoxy groups, and the like. Particularly preferred are carboxyl groups or salts thereof, acid anhydride groups, epoxy groups, and the like. Two or more types of these groups may be contained in the resin.

It is preferable that the alkyl acrylate or alkyl methacrylate in the acrylic resin be 30 mol% or more in terms of coating formability and coating film strength.

This is because blocking resistance becomes better. The reason why the alkyl acrylate or alkyl methacrylate content in the acrylic resin is preferably 99.9 mol% or less is that by introducing a compound having a specific functional group as a copolymerization component into the acrylic resin, water solubilization, water This is to facilitate dispersion and to stabilize the state over a long period of time, as well as to improve the adhesion between the coating layer and the polyester film layer, and to increase the strength of the coating layer through reactions within the coating layer.

This is because it is possible to improve water resistance and chemical resistance, and also to improve adhesion between the film of the present invention and other materials.

An example of an alkyl group in an alkyl acrylate or alkyl methacrylate is a methyl group.

Examples include ethyl group, n-prokyl group, isoprokyl group, n-butyl group, isobutyl B, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, and cyclohexyl group.

As the vinyl monomer having a functional group copolymerizable with alkyl acrylate or alkyl methacrylate, the following compounds having functional groups such as a reactive functional group, a self-crosslinking functional group, and a hydrophilic group can be used.

Examples of compounds having a carboxyl group, a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

Examples include crotonic acid, metal salts of these carboxylic acids with sodium, ammonium salts, and maleic anhydride.

Examples of compounds having a sulfonic acid group or a salt thereof include vinylsulfonic acid and styrenesulfonic acid.

Metal salts of these sulfonic acids, such as sodium.

Examples include ammonium salts.

Examples of compounds having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, ureido vinyl ether, β-ureido isobutyl vinyl ether,
Examples include ureidoethyl acrylate.

Examples of compounds having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl Examples include vinyl ethers, those obtained by methylolizing their amino groups, and those obtained by converting their amino groups into quaternary chlorides using alkyl halides, dimethyl sulfate, sultone, and the like.

Examples of compounds having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate,
β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate.

Examples include β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, and polypropylene glycol monomethacrylate.

Examples of compounds having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

In addition to the above compounds, the following compounds may be used in combination. i.e. acrylonitrile, methacrylonitrile,
Styrenes, butyl vinyl ether, maleic acid mono- or dialkyl esters.

Fumaric acid mono- or dialkyl esters, itaconic acid mono- or dialkyl esters, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl acetate, vinylpyridine, vinylpyrrolidone.

Examples include, but are not limited to, vinyltrimethoxysilane.

Acrylic resins may contain surfactants, but the low-molecular-weight surfactants contained in acrylic resins may condense during the film-forming process and accumulate at the interfaces between particles, or may cause problems in the coating layer. This may cause problems with the mechanical strength, water resistance, and adhesion of the coating layer to the laminate. In such a case, a polymer obtained by so-called soap-free polymerization that does not contain a surfactant can be used.

However, among these, a copolymer of methyl methacrylate and methyl acrylate with a molar ratio of 35/65 to 65/35 is used as a polymer, and is called -COOH.

Particularly suitable are water-dispersible acrylics each incorporating 1 to 5% by weight of -CH20H.

The coating layer in the present invention includes -
5% by weight of polymer whose main constituent is repeating units called crests.
It is necessary that the content be 60% by weight or less. If the amount is less than 5% by weight, the antistatic properties will be insufficient, which is undesirable, while if it is more than 60% by weight, the transferred toner will become thinner, or if it is significant, it will scatter, which is not preferred. In particular, when the amount is 10% by weight to 30% by weight, the toner adhesiveness and antistatic property are well balanced, which is preferable.

The thickness of the coating layer is not particularly limited, but is usually 0°001
~5 μm. The thickness is preferably from 0.01 to 0.9 μm, more preferably from 0.04 to 0.5 μm, from the viewpoint of adhesiveness and antistatic properties.

The inert inorganic particles in the present invention need only have an average particle size within the range of the present invention, and the type thereof is not particularly limited, but a typical example is talc.

Kaolin, calcium carbonate, titanium oxide, silicon oxide,
Mention may be made of calcium fluoride, lithium fluoride, alumina, barium sulfate, zirconia, mica, and calcium phosphate. However, among these, it is particularly preferable to use inert inorganic particles in an inorganic colloidal state.

The inorganic colloid as used in the present invention is defined in Kyoritsu Shuppansha Kagaku Daijisen, and contains 105 to 109 atoms in one particle. Depending on the element, it can be obtained as a metal colloid, oxide colloid, or hydroxide colloid. Preferably used metal colloids include gold, palladium, platinum, silver, and sulfur; examples of oxide colloids, hydroxide colloids, carbonate colloids, and sulfate colloids include zinc, magnesium, silicon, calcium,
Aluminum, strontium, barium.

Zirconium, titanium, manganese, iron, cobalt.

Oxide colloids such as nickel and tin, hydroxide colloids, carbonate colloids, and sulfate colloids are preferably used in the present invention. For example, silicic acid colloids obtained by adding silicon tetrahalide to water or gradually adding concentrated hydrochloric acid to an aqueous solution of alkali silicate are very preferably used in the present invention.

The average particle size of the inorganic colloid is 0.08-2.0 μm, preferably 0.10-0.8 μm, more preferably 0.15 μm.
It is necessary that it is in the range of ~0.50 μm. If the average particle diameter is 0.08 μm or less, the slipperiness of the laminated film will be insufficient. Furthermore, since the agglomeration of the particles increases, the transparency tends to decrease due to the generation of coarse foreign matter. If the thickness exceeds 2.0 μm, not only will the surface of the laminated film become noticeably rough and the abrasion resistance will deteriorate,
The stability of inorganic colloid particles in an aqueous solution deteriorates significantly, and in some cases, particles may precipitate or aggregate.

Gelation, etc. occurs. Furthermore, during collection and reuse of film flakes, particles are mixed in, which promotes surface roughness of the film and deteriorates its smoothness.

Note that the average particle size here refers to the inorganic colloid aqueous solution measured using a centrifugal sedimentation type particle size distribution analyzer (5A-C manufactured by Shimadzu Corporation).
P2 type).

The content of inert inorganic particles in the coating layer is 0°1 to 30
% by weight is preferable, more preferably 0.5 to 20% by weight.
, more preferably in the range of 1.0 to 15% by weight. When the content of inert inorganic particles is less than 11% by weight of O. It is difficult to obtain a laminated film with the desired slipperiness. If it exceeds 30% by weight, the transparency, easy adhesion, and abrasion resistance of the laminated film will deteriorate, and the adhesion of the coating layer to the base film will decrease, which is not preferable.

The polyester film constituting the film of the present invention is at least two-wheel oriented by a conventional method, and the thickness is preferably 2 to 300 μm, more preferably 5 to 150 μm for practical handling as a base material. Excellent. Further, the haze (turbidity) of the polyester film is not particularly limited, but is usually 10% or less, preferably 6% or less, and more preferably 3.0% or less.

In addition, the heat shrinkage rate of the film of the present invention at 150°C is in the longitudinal direction,
1.0% or less in both the width direction, preferably 0.4% in the longitudinal direction
Hereinafter, it is necessary that it be 0.1% or less in the width direction.

This is not preferable if the heat shrinkage rate is greater than 1%, since the flatness of the resulting film is significantly deteriorated during the process of attaching toner to the film. Also, the heat shrinkage rate in the longitudinal direction is 0.4% or less, the heat shrinkage rate in the width direction is 0°1% or less, and more preferably -1°5% in both the longitudinal and width directions.
If it is -0.3% or less, the flatness of the film becomes even better, which is preferable.

The film of the present invention has a ratio (d/T) of the average particle diameter (d) of the inert inorganic particles in the coating layer to the thickness (T) of the coating layer from 1.1 to
Must be 80. It is preferably in the range of 2.0 to 40, more preferably 3.0 to 15. d/T is 1.
If it is less than 1, the multi-feedability of the laminated film deteriorates and adverse effects such as surface defects increase, which is not preferable. When d/T exceeds 80, the abrasion resistance of the coating layer deteriorates, making white powder more likely to occur, or conversely, the slipperiness deteriorates, which is not preferable.

Next, a typical method for manufacturing the composite film of the present invention will be described, but the method is not limited thereto.

First, a polyester pellet containing a compound containing sulfonic acid or a sulfonate salt and various other additives as necessary is thoroughly dried and placed in a known extruder, preferably a melt extruder with a compression ratio of 3.8 or more. The pellets are supplied, melted and extruded into a sheet through a slit die at a temperature above the melting temperature of the pellets and below the temperature at which the polymer decomposes, and then cooled and solidified to produce an unstretched sheet. After a predetermined coating layer is provided on the unstretched sheet or a film obtained by stretching the unstretched sheet 3 to 8 times at 80 to 105°C, the unstretched film is stretched at 80 to 130°C in the longitudinal direction. Simultaneous biaxial stretching is carried out 3 to 6 times, 3 to 6 times in the transverse direction, or 3 to 6 times in the transverse direction when a -axially stretched film is used. Further, if necessary, heat treatment is performed at 150° C. to 250° C. for 0.1 to 10 seconds while providing 0 to 10% relaxation.

Further, if necessary, the film may be stretched again in the longitudinal direction by 1.1 to 1.7 times.

It goes without saying that coating may also be carried out on a composite of a polyester to which a compound containing sulfonic acid or a sulfonic acid salt has been added and a normal polyester.

Before coating on a film, corona discharge treatment may be performed in air or other various atmospheres, if necessary. Anchor treatment may also be performed using a known anchor treatment agent such as urethane resin or epoxy resin, but this is usually not necessary.

The coating method is not particularly limited, and extrusion lamination and melt coating methods may be used, but gravure coating and reverse coating using paint dispersed in water or various solvents are preferred because they enable thin film coating at high speed. , spray coat.

Preferably, it is coated with a kit, die coated, or metallized barcoded.

In particular, it is more preferable to stretch the coating layer after applying it, since this further improves the adhesion to the base material.

The thus obtained laminated film of the present invention can be preferably used as a printing film for various copying machines and printers such as PPC, laser printers, and electrostatic plotters.

Next, a method for evaluating characteristics and effects will be explained.

(1) Heat shrinkage rate: 15 based on JIS-C2318
The heat shrinkage rate in the longitudinal direction and the width direction at 0°C is evaluated.

(2) Flatness: FUJI
After transferring the PPC toner using the ROX4790, it is projected using a reflective overhead projector. At that time, characters that could be read well were evaluated as "O", and characters that were difficult to read were evaluated as "x".

(3) Transparency: JI turbidity of 100μm film
Measured based on S-ni-6714-58.

If the turbidity is 10% or more, the transparency is "x", and if it is less than that, it is "transparency".
○”

(4) Multi-feeding ability: 30 sheets of specified film FUJI
Insert into XEROX5870 and perform continuous copying. At that time, the case where no double feeding (a phenomenon in which two or more films are fed) did not occur at all was designated as "○", and the case where double feeding occurred was designated as rXJ.

(5) Toner adhesion: FUJI XEROX4790
to transfer the toner. Immediately after the transferred toner and after rubbing it by hand 10 times, each toner was peeled off in a 90° direction using a cellophane adhesive tape manufactured by Chiban ■ (registered trademark "Cello Tape"), and the state of the toner peeling was evaluated. Those in which sufficient toner remained were evaluated as "1" in each straight line, and the toner adhesion in the fir resistance was evaluated as "○", and the others were evaluated as "x".

(6> Toner transferability: Transfer the toner in the same manner as in (5). If the transferred toner is partially cut off in the fine print area, mark it as "poor text" or "×", otherwise mark it as rOJ. Judgment was made. Also, those with scattered black solid parts were classified as "skip" and "
×”, and otherwise “○”.

(7) The surface of the coating layer of the abrasion-resistant tape-shaped film is made of metal (SUS).
After repeatedly running in contact with a fixed guide (5InIn, 12r) 100 times, the amount of scratches adhered to the film was observed, and the number of scratches was judged as follows.

◎Very few varnish scratches (extremely good durability) O: Few varnish scratches (good durability) Adhesive tape is applied, and the coating layer at the end of the cellophane adhesive tape is dissolved and removed using a solvent such as dimethylformamide. Next, the cellophane adhesive tape was peeled off, and the boundary between the surface protected by the cellophane adhesive tape and the surface that had been dissolved and removed was measured using an ET-10 high-precision step measuring device manufactured by Kosaka Institute to determine the thickness.

If the above method was difficult, an ultra-thin section of the laminated film was observed using a transmission electron microscope model HU-12 manufactured by Hitachi, Ltd., and the thickness was determined.

(9) Ratio (d/
T) The average particle diameter (d) and the lamination thickness (T
>, the ratio (d/T) was determined.

[Example] The present invention will be explained using the following examples and comparative examples, but the present invention is not limited to these examples.

Examples 1-9. Comparative Examples 1 to 7 Polyethylene terephthalate with an intrinsic viscosity of 0.61 to which 0.02% silicon oxide with an average particle size of 1.0 μm was added,
Terephthalic acid 82 mol% and isophthalic acid 8 mol% as acid components
Mol% and sodium salt of 5-sulfoisophthalic acid 1
0 mol%, and a resin mixed with various amounts of a polyester copolymer with a molecular weight of about 30,000 using ethylene glycol as a diol component (S2 in the resin surface layer).
．． /C1, shown in the table) was dried under reduced pressure at 180'C for 2 hours, then melted at 285°C using a screw with a compression ratio of 3.8, and extruded into a cooling drum with a surface temperature of 50'C. did. At this time, the time from polymer injection to polymer discharge was 18 minutes. The film thus obtained was
After stretching 4 times in the longitudinal direction at 5°C, the main component is a 50:50 copolymer of methyl methacrylate and butyl acrylate, and 2.5 mol% each of carboxyl groups and methylol groups are introduced as functional groups. Water-dispersible acrylic resin with a molecular weight of 500,000, VER3A-TL125 (manufactured by Kanebo NSC ■) as a sulfonated polystyrene with NH4+ as the X+ ion of 3020-X+ and a weight average molecular weight of about 70,000, and average particles. Silicon oxide particles with different diameters are applied at different solid content ratios (the mixing ratios are shown in the table). The coating layer was stretched 3.5 times in the transverse direction at 110°C while drying, and then stretched at 215°C.
Heat treated at 170°C with 5% relaxation in the transverse direction.
It was relaxed by 0.5% in the vertical direction. However, in the case of Comparative Example 5, longitudinal stretching was performed at 80° C. for 5 times, and relaxation treatment in the longitudinal and width directions was not performed. In the case of Example 7, the relaxation rate in the lateral direction was set to 3%, and no relaxation was performed in the vertical direction. The thickness of the film obtained at this time was 100 μm, and the thickness of each coated layer was 0.07 μm.

As shown in the table, toner adhesion is within the range of the present invention.
It can be seen that it has an excellent balance between flatness, multi-feedability and transparency.

Example 10 Sulfonated polystyrene (in the form of sodium salt) was added as a compound to be mixed with polyethylene terephthalate, and film formation was evaluated in the same manner as in Example 1. It can be seen that it exhibits similarly excellent characteristics.

[Effects of the Invention] In the present invention, the concentration of sulfonic acid or sulfonate in the film surface layer is 0.002.
By applying a specific resin composition to a specific thickness on a bound polyester film of ~2.0% by weight, the following excellent effects could be obtained.

(1) Shows excellent toner adhesion and multi-feeding properties.

(2) Shows excellent transparency.

(3) Toner adhesion and excellent flatness.

Claims (3)

[Claims] (1) A composite film in which a coating layer is provided on at least one side of a polyester film, wherein the concentration of sulfonic acid or sulfonate in the surface layer of the polyester film is 0.002 to 2.0%, and the polyester film The heat shrinkage rate at 150℃ is 1.0% or less in both the longitudinal and width directions, and the coating layer has a general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R is hydrogen or methyl group, M is Hydrogen, alkali metal, alkaline earth or ammonium, R_1, R_2,
R_3 and R_4 are hydrogen, halogen, alkyl group, or alkoxy group respectively).
Weight% resin content and average particle size 0.08-2.0μm
The ratio (d/T) of the average particle diameter (d) of the inert inorganic particles to the thickness (T) of the coating layer is 1.
A composite film characterized in that the number is 1 to 80. (2) The composite film according to claim 1, wherein the coating layer is stretched. (3) The composite film according to claim 1 or 2, characterized in that the heat shrinkage rate at 150° C. is 0.4% or less in the longitudinal direction and 0.1% or less in the width direction.