JP3248333B2 - Laminated polyester film - Google Patents

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. More specifically, the present invention relates to a laminated polyester film having excellent slipperiness, smoothness, easy adhesion, transparency, abrasion resistance, running properties, and durability.

[0002]

2. Description of the Related Art In recent years, as magnetic recording media have become smaller and lighter or have been recorded for a longer time, it has become necessary to record information at a higher density. For high-density recording, it is necessary to shorten the recording wavelength and reduce the spacing loss between the magnetic recording medium and the magnetic head as much as possible. With this, the surface of the magnetic recording medium becomes smoother. It is desirable. Above all, a magnetic recording medium obtained by forming a ferromagnetic thin film on a base film by a method such as electroplating, vacuum deposition, sputtering, or ion plating has a larger magnetic layer than a conventional coating type magnetic recording medium. Since the thickness can be reduced to about 1/30 or less, it is possible to reduce the thickness loss due to the shortening of the recording wavelength and to use a smooth base film to make the surface of the magnetic recording medium smoother. This is extremely effective for high-density recording, for example, by reducing the spacing loss between magnetic heads. Research and development of such a ferromagnetic thin film type magnetic recording medium have been actively conducted, and various studies have been made on the base film. As such a base film, for example, a coating layer having fine projections made of a mixed composition of a fluorine-based compound, a resin and fine inert particles on a base film as disclosed in JP-A-60-957 is used. Provided laminated polyester films are disclosed. Japanese Patent Application Laid-Open No. 60-76340 discloses a laminated polyester film in which a particulate substance composed of a primer is fixed on a base film composed of a polyester film in an area of 1% or more of the total surface area of the polyester film. .

[0003]

However, the above-mentioned laminated polyester film has the following problems. That is, as described in JP-A-60-957, a laminated polyester film provided with a coating layer having fine projections made of a mixed composition of a fluorine compound, a resin and fine inert particles retains excellent lubricity. However, it is difficult to uniformly disperse the fine inert particles in the coating layer, and furthermore, it is difficult to obtain a stable smoothness because coarse projections are easily generated by the aggregated particles. The running durability and the electromagnetic conversion characteristics of the magnetic recording medium were reduced due to the falling off of the magnetic recording medium. Also, as described in JP-A-60-76340, in a laminated polyester film in which the occupied area of the particulate material composed of the primer is 1% or more of the total surface area of the polyester film, if the occupied area of the particulate material increases, the sliding occurs. The phenomenon that the property became extremely bad was seen. The present invention overcomes these shortcomings of the prior art,
An object of the present invention is to provide a laminated polyester film having excellent lubricity, smoothness and adhesiveness.

[0004]

According to the present invention, at least one surface of a polyester film is provided with 1 × 10 ⁶ projections / mm ² of particles having a shell core structure whose exterior is softer than the interior.
The laminated polyester film having the above
The core part of the particles having a rucoal structure has a crosslinkable acrylic or
Polyethylene based on Tylene / divinylbenzene copolymer
The laminated polyester film characterized in that it consists Ma is to its gist.

[0005] The polyester constituting the polyester film in the present invention is a generic name of polymers having an ester bond as a main bonding chain of a main chain. Particularly preferable polyesters are polyethylene terephthalate and polyethylene 2 , 6-naphthalate, polybutylene terephthalate, polyethylene α, β-bis (2-chlorophenoxy) ethane 4,4-dicarboxylate, etc. Among these, the quality and economy are comprehensively evaluated. Considering this, polyethylene terephthalate is most preferred. Therefore, hereinafter, polyethylene terephthalate (hereinafter abbreviated as PET) will be described as a typical example of polyester. PE
T means that 80 mol% or more, preferably 95 mol% or more has ethylene terephthalate as a repeating unit, but other dicarboxylic acid components and diol components may be partially copolymerized. Also known additives in this PET, for example, heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, A nucleating agent may be blended.
The intrinsic viscosity (measured in orthochlorophenol at 25 ° C.) of the above PET film is 0.40 to 1.20 dl /
g preferably in the range of 0.50 to 0.80 dl / g is suitable for the content of the present invention. The polyester film of the present invention is preferably biaxially oriented in view of mechanical and thermal properties. For example, a biaxially oriented PET film when the above PET is used as polyester is a non-stretched PET. It is made by stretching the sheet or film in the longitudinal direction and the width direction by about 2.5 to 5 times, and shows a biaxially oriented pattern by wide-angle X-ray diffraction.

In the present invention, the particles having a shell core structure (hereinafter sometimes abbreviated as shell core particles) refer to polymer fine particles having a multilayer structure in which the inside and the outside are made of polymers having different properties. In this case, the multilayer is 2
It refers to a layer or more, and the property may change continuously in the radial direction. The outside (hereinafter sometimes abbreviated as a shell portion) has a function of reacting with the film base after being coated on the film or performing a heat treatment to react, melt, soften or deform and adhere to the film base. (Hereinafter, it may be abbreviated as a core part) is considered to have a function as a so-called particle that gives the film an appropriate sliding property together with the shell part. From the viewpoint of the above-mentioned functions of the shell and the core, the shell is required to have excellent affinity with the film base and to have appropriate physical, chemical and thermal properties at the film-forming heat treatment temperature. The core portion is required not to be deformed by mechanical friction or the like and to have a relatively high hardness relative to the shell portion.

As a polymer composition for realizing such a function, a thermoplastic resin is generally preferable for the shell portion, and an acrylic resin, a polyester resin and the like are particularly preferable. In order to further increase the affinity with the film base, a functional group having reactivity or affinity with the film base at an arbitrary ratio in the molecule, specifically, a carboxyl group,
A hydroxyl group, glycidyl group, amide group, epoxy group, isocyanate group or the like may be introduced. These functional groups may be used alone or in combination of two or more. The glass transition temperature (hereinafter, abbreviated as Tg) of the shell portion is preferably 80 ° C. or lower, more preferably 40 ° C. or lower.
If the Tg exceeds 80 ° C., the shell core particles fall off from the film. By using such a polymer having the above composition in the shell portion, excellent abrasion resistance can be exhibited. Above all, acryl and / or polyester are preferably used from the viewpoints of affinity with the core polymer, adhesion to the substrate, protrusion holdability, and slipperiness. This acryl is not particularly limited, either homopolymer or copolymer may be used, but a copolymer is preferably used because it is easy to change the glass transition point or the film forming temperature. For example, methyl methacrylate (hereinafter sometimes abbreviated as MMA), ethyl acrylate (hereinafter sometimes abbreviated as EA),
Butyl acrylate is a typical example. If necessary, acrylic acid (hereinafter sometimes abbreviated as AA), N-methyl acrylamide (hereinafter N-MA)
(May be abbreviated as M) can be copolymerized in an appropriate molar ratio as long as the effects of the present invention are not impaired. This gives a ternary or quaternary acrylic copolymer. Further, as the polyester constituting the shell portion, a combination of a highly polar group and a hydrophobic group in the molecule is preferable. As a polar group, a hydroxyl group, an acid group, an ether, an ester group,
Epoxy, sulfonic acid groups, urethane bonds, and other hydrophobic moieties that contain an aliphatic chain, an aromatic chain, etc. are preferred, and include polyester ether copolymers, polyethylene glycol.
A polyester copolymer containing a sulfonic acid alkali metal salt can be used.

[0008] On the other hand, the present invention is particularly concerned with the core portion.
Crosslinkable acrylic or styrene / divinylbenzene
A polymer mainly composed of a polymer is used. Of course, this
Or a ternary copolymer containing as a main component.
For example, a styrene / divinylbenzene binary copolymer, a styrene / divinylbenzene / ethylenedivinylbenzene terpolymer (for example, a copolymerization ratio of 45/50/5 wt%)
Such highly crosslinkable polymers can be mentioned. Further, preferred self-crosslinkable acrylic copolymer as a crosslinkable acrylic, such as a functional group-containing vinyl polymerizable monomer, a hydrocarbon vinyl polymerizable monomer, a hydrocarbon non-conjugated divinyl polymerizable monomer Although a copolymer compound is mentioned, in the present invention, a copolymer of a functional group-containing vinyl polymerizable monomer is preferably used. Examples of the functional group-containing vinyl polymerizable monomer include acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-methylolacrylamide, N-butoxymethylacrylamide, diacetone acrylamide, methylol diacetone acrylamide, 2- Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate
And the like are selected from these, but are not particularly limited. In addition, a crosslinkable acrylic
Le is 70 wt% or more, preferably 80 wt% or more, more preferably one containing 90 wt% or more. Also,
Accession of the crosslinkable acrylic already crosslinked by a crosslinking component
Lil. These crosslinkable acrylic and highly crosslinked polystyrene
Preferably, the vinyl / divinylbenzene copolymer does not thermally deform at the ordinary polyester film forming temperature.

[0009] Particularly preferred combinations of the shell portion polymer and the core part polymer, as a shell part polymer, acrylic resin or polyester resin, crosslinkable A acrylic, styrene / divinylbenzene copolymers as the core part polymer.

When the shell core particles are composed of two layers,
The shell / core weight ratio can be freely selected, but is preferably 100/1 to 1/10, more preferably 10/1.
~ １ ／ is desirable. Shell / core weight ratio of 100/1
As the size increases, the organic particles do not have a multi-layer structure, and the properties of the particles become stronger, and deformation due to heat or mechanical friction increases. When the ratio is smaller than 1/10, the properties of inorganic particles become stronger, and the adhesion to the film decreases,
The dropout of the particles becomes remarkable. In either case, the processability of the film is likely to be adversely affected.

The shape of the particles may be any of a spherical shape, an elliptical shape, a rectangular shape, a cubic shape and the like, but spherical particles are particularly preferred.

The average particle size is preferably in the range of 3 to 100 nm, more preferably 5 to 50 nm, and the particle size distribution is preferably uniform. If the average particle size is less than 3 nm, the slipperiness and the abrasion resistance deteriorate, and when the film is rolled, a blocking phenomenon is liable to occur. The average particle size is 100 nm
If the magnetic recording medium is processed into a magnetic recording tape or the like, the spacing with the magnetic head becomes large, and it may be difficult to provide a high-density magnetic recording medium.

In order to obtain projections composed of particles having a shell core structure of the present invention, it is possible to apply a coating agent containing shell core particles on a polyester film, and then dry and stretch horizontally. In the projection made of particles having the shell core structure of the present invention, a core having a high cross-linking property and / or a cross-linkable polymer is used as the core, so that the projection forming ability is high. Since the structure includes a soft material, it is possible to form a projection that is less likely to fall off and that is strong against scraping.
When the projections are formed of a hard material such as a highly crosslinked polymer and / or a crosslinkable polymer, defects such as dropouts of the projections and excessive height of the projections occur. Conversely, it is not preferable to form the projections only with a soft material such as a thermoplastic polymer, because the deformation due to heat is too large and the ability to form projections is extremely poor, and it is difficult to form uniform projections. Further, when it is attempted to form a projection by blending a thermoplastic polymer or the like with a hard material such as a highly crosslinked polymer and / or a crosslinkable polymer, the interaction between the core polymer and the shell polymer found in the particles of the shell core structure is reduced. Insufficiently, voids (so-called voids) are generated around the core, so that transparency is impaired, and particles fall off due to insufficient cohesion, which is not preferable.

In the present invention, the cross-sectional area of the void formed around the core portion forming the projection is 10 times the cross-sectional area of the core portion.
%, Preferably 5% or less, more preferably 3% or less. For the reasons described above, the projections made of the particles having the shell core structure of the present invention have extremely few voids. In order to balance these conflicting phenomena, the particles having the shell core structure of the present invention are optimal.

The method for producing the particles having a shell core structure of the present invention is not particularly limited, and the particles can be easily produced by using ordinary emulsion polymerization. For example, first, first-stage emulsion polymerization is performed using a monomer, an emulsifier, a polymerization initiator, and water to form a core portion of a polymer particle, and after the polymerization is substantially completed, a shell portion is formed. The monomer to be formed and the polymerization initiator are added, and the second-stage emulsion polymerization is performed. At this time, in order to form the synthetic resin particles having a two-layer structure, in the second-stage emulsion polymerization, the emulsifier is not added, or even if added, the amount is such that no new particles are formed. It is advantageous to consider that the polymerization proceeds substantially in the polymer particles formed in the above. The core (nucleus) of the highly crosslinked or crosslinkable polymer of the present invention
As described above, particles having a shell-core structure with a thermoplastic polymer (shell) added therearound can be obtained by a process such as the two-stage emulsion polymerization described above.

The form of the shell-core structured particles of the present invention is not particularly limited, but an aqueous dispersion is preferably used from various aspects such as sanitary environment, explosion-proof, uniformity of projection formation, stability and handling properties. The solid content of the aqueous dispersion is not particularly limited, but is preferably 50% by weight or less from the viewpoint of stability, storage stability, anti-agglomeration property and the like of the aqueous dispersion.

In applying the shell core structure particles of the present invention to a film substrate, it is preferable that other inorganic particles, organic particles, inorganic colloids and the like are not contained from the viewpoint of abrasion resistance and the like. A small amount may be added as long as the properties are not impaired. In that case, the addition amount of the particles is preferably 10 parts by weight or less, more preferably 5 parts by weight or less based on 100 parts by weight of the resin. If the effects of the present invention are not impaired, in order to improve the flatness, lubricity, adhesiveness, etc. of the projections, the shell core structure particles should have a cellulose-based height such as methylcellulose and ethylcellulose. Molecules or various surfactants, various coupling agents (silane, titanium, etc.) may be added. The addition amount is preferably in the range of 1 to 30%, and more preferably 3 to 20%, based on the solid content of the shell core structure particles.

In the present invention, it is preferable to form the projections only with the shell core structure particles in order not to impair the smoothness and particle morphology of the projections. However, in order to further improve the adhesion and mechanical strength, the projections are preferably formed. May contain a water-soluble copolymerized polyester or a crosslinking agent.

The water-soluble copolymerized polyester in the present invention is not particularly limited. However, it is preferable that the aromatic dicarboxylic acid is 60 mol% or more as an acid component from the viewpoint of anti-blocking properties and solvent resistance. The aromatic dicarboxylic acid is not particularly limited, but preferred dicarboxylic acids are terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. The water-soluble copolymerized polyester of the present invention may contain an ester-forming sulfonic acid alkali metal salt compound in an amount of 5 to 40 with respect to all the acid components in view of imparting water solubility.
It is preferable to add mol%. When the amount of the ester-forming sulfonic acid alkali metal salt compound is less than 5 mol%, sufficient water solubility and adhesiveness cannot be obtained. On the other hand, if it exceeds 40 mol%, the adhesiveness reaches saturation, and conversely, the anti-blocking property and the solvent resistance decrease. The ester-forming sulfonic acid alkali metal salt compound is not particularly limited, but may be, for example, sulfoterephthalic acid, 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2, Examples thereof include alkali metal salts such as 6-dicarboxylic acid, and among them, lithium, sodium, and potassium salts of 5-sulfoisophthalic acid and sulfoterephthalic acid are preferably used.

The glycol component of the water-soluble copolymerized polyester of the present invention is not particularly limited, but may be aliphatic glycols having 2 to 8 carbon atoms and / or 6 to 6 carbon atoms.
Preferred are 80 to 99 mol% of 16 alicyclic glycols and 3 to 18 mol% of diethylene glycol. When the aliphatic glycol having 2 to 8 carbon atoms and / or the alicyclic glycol having 6 to 16 carbon atoms is less than 80 mol% or the diethylene glycol exceeds 20 mol%, blocking resistance is obtained.
It is not preferable because the slipperiness and the solvent resistance become poor.
On the other hand, when the amount of aliphatic glycol having 2 to 8 carbon atoms and / or the number of alicyclic glycols having 6 to 16 carbon atoms exceeds 99 mol%, or when the content of diethylene glycol is less than 1 mol%, blocking resistance is reduced. Although the property is good, it is inferior in water solubility and adhesiveness.

An aliphatic glycol having 2 to 8 carbon atoms and / or
Alternatively, examples of the alicyclic glycol having 6 to 16 carbon atoms include ethylene glycol, 1,2-propanediol,
1,3-propanediol, neopentyl glycol,
1,3-butanediol, 1,4-butanediol,
1,5-pentanediole, 1,6-hexanediol-
And glycols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Among them, ethylene glycol is preferred. , Neopentyl glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. These glycols may be used alone or in combination of two or more.

In addition to the above-mentioned acid component and glycol component, the water-soluble copolyester in the present invention may contain an aliphatic dicarboxylic acid, an oxyacid or a monofunctional compound or a trifunctional or higher functional compound within a range not to impair the effects of the present invention. It may contain other components such as a polyfunctional compound. The content of these other components is not particularly limited as long as the effects of the present invention are not impaired, but is usually about 30 mol% or less.

In the water-soluble copolymerized polyester of the present invention, it is more preferable that the composition described above contains less than 40% by weight of polyoxyalkylene glycol. Too much polyoxyalkylene glycol results in poor water solubility. Polyoxyalkylene glyco-
The type of the component is not particularly limited, but from the viewpoint of excellent water solubility, adhesiveness, etc., the polyoxyalkylene glyco-
The number average molecular weight of the metal component is preferably from 600 to 4000. Examples of such a polyoxyalkylene glycol component include, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Is preferred.

The method of incorporating the polyoxyalkylene glycol component of the present invention into a copolymerized polyester is not particularly limited. For example, the polyoxyalkylene glycol component may be added at any stage in the process of producing the copolymerized polyester. A method of adding, or a method of melt-kneading a copolymerized polyester and a polyoxyalkylene glycol component using an extruder or the like can be used. On this occasion,
The polyoxyalkylene glycol component can be added by any method such as powder, melting, or solution.

The intrinsic viscosity of the water-soluble copolymerized polyester of the present invention is not particularly limited, but is preferably 0.3 dl / g or more in view of adhesiveness, and more preferably 0.4 dl / g.
1 / g or more is preferable. The water-soluble copolymerized polyester of the present invention is dissolved in water and used as an aqueous solution. This aqueous solution does not have strictness in a physical or chemical sense, and includes an aqueous solution which is mostly dissolved in water and partially finely dispersed.

The role of the water-soluble copolymerized polyester in the present invention is to play a role of more firmly adhering the projections on the polyester film substrate when forming projections composed of particles having a soft shell core structure from the inside to the outside. In addition, since the entire projection is covered with a water-soluble copolymerized polyester film, the particles are prevented from falling off and the height of the projection is adjusted. At this time, by containing a polyoxyalkylene glycol component in the water-soluble copolymerized polyester,
It can improve adhesiveness, abrasion resistance, solvent resistance and the like. This is due to the crystallinity of the polyoxyalkylene glycol component, and it is presumed that the inclusion of the polyoxyalkylene glycol component in the water-soluble copolymerized polyester increases the crystallinity of the coating film. I have.

The production of the water-soluble copolymerized polyester of the present invention can be carried out by any conventionally known method, and is not particularly limited. For example, a copolymer polyester comprising terephthalic acid as an acid component, 5-sodium sulfoisophthalic acid and ethylene glycol as a glycol component, and diethylene glycol, will be described.
Terephthalic acid, 5-sodium sulfoisophthalic acid and ethylene glycol or diethylene glycol may be directly esterified, or alkyl ester of terephthalic acid, alkyl ester of 5-sodium sulfoisophthalic acid and ethylene glycol, diethylene glycol
And a second step of subjecting the reaction product of the first step to a polycondensation reaction. At this time, a conventionally known alkali metal, alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, titanium compound or the like is used as a reaction catalyst, and a phosphorus compound or the like may be used as a coloring inhibitor.

The solid content ratio between the shell core structure particles and the water-soluble copolymerized polyester is in the range of 95/5 to 5/95, preferably 80/20 to 20/80. If the ratio of the water-soluble copolymerized polyester is too low, the protrusion-holding property tends to be low. Conversely, if the ratio is too high, the surface roughness is increased, and aggregation of the particles tends to occur.

The cross-linking agent referred to in the present invention is a cross-linking reaction with a functional group present in an acrylic copolymer, for example, a hydroxyl group, a carboxyl group, a glycidyl group, an amide group, etc., and finally a three-dimensional network structure. The crosslinking agent is not particularly limited as long as it has a urea type, a methylol type, or an alkylol type urea type, a melamine type,
Examples include acrylamide-based, polyamide-based resins, epoxy compounds, isocyanate compounds, and aziridine compounds. Of these, methylolated melamine and isocyanate compounds are preferred in terms of adhesion to the base film, mechanical strength, and the like. These crosslinking agents may be used alone or in combination of two or more in some cases. The amount of the cross-linking agent to be added is appropriately selected depending on the type of the cross-linking agent.
Part by weight is preferred, and 0.1 to 30 parts by weight is more preferred. If the addition amount is less than 0.01 parts by weight, the crosslinking effect is low,
If the amount exceeds 50 parts by weight, the adhesion of the projections may decrease,
Further, the coatability deteriorates and it is difficult to form a uniform layer. A crosslinking catalyst may be used in combination with the crosslinking agent. Known catalysts such as salts, inorganic substances, organic substances, acid substances, and alkaline substances can be used as the crosslinking catalyst. The amount of the crosslinking catalyst to be added is 0.001 to 1 with respect to 100 parts by weight of the resin solid content.
0 parts by weight, preferably 0.1 to 5 parts by weight. The coating agent to which the crosslinking agent is added is cross-linked by heating, ultraviolet rays, electron beams or the like after being applied to the base film, but a method by heating is generally used.

The protrusion in the present invention is composed of granular shell-core structure particles formed on the surface of the base polyester film. By forming the shell-core structure particles, the core polymer is highly cross-linked or cross-linkable polymer, so that fine uniform protrusions are obtained. While maintaining the form, while being included in the shell polymer, the shell polymer adheres to the base polyester film by heat melting or heat softening, and is adhered to the base polyester film by adhesive force or the like. Is done. The shell polymer also plays a role in adjusting the height of the core polymer serving as a core.

The thickness of the polyester film as the base film in the present invention is not particularly limited, but the range of 1 to 500 μm, preferably 3 to 250 μm is excellent in handleability in practical use as the base film. . Also, the surface roughness (Ra) of the polyester film
The surface roughness (Ra) is 0.03 μm or less, preferably 0.01 μm, although the haze and optical haze are not particularly limited.
It is desirable that it is not more than μm. The projections comprising shell core structure particles constituting the film of the present invention preferably have a lamination thickness including the projections of from 0.0001 to 0.05 μm.
The range of 001 to 0.025 μm is more preferable. If the lamination thickness is less than 0.0001, not only uniform lamination is difficult but also lubricious projections are difficult to obtain. If the thickness exceeds 0.05 μm, the projections have a film-forming property, and it is difficult to form the projections. The projections may contain a reactive compound such as an epoxy compound, an aziridine compound, a vinyl compound, or a silane coupling agent as an adhesion promoter for the base polyester film or the magnetic layer. Further, if necessary, known additives in an amount that does not impair the effects of the present invention, for example, a coating improver, an antistatic agent, an antioxidant, an ultraviolet absorber, a rust inhibitor, a dye, an antifoaming agent, A thickener or the like may be included.

In the present invention, the number of projections composed of shell core structure particles per unit area must be 1 × 10 ⁶ / mm ² or more, preferably 1 × 10 ⁷ / mm ² or more. 5 × 10 ⁷ pieces / mm ² or more. When the value is more than this value, when a ferromagnetic thin film is formed, the lubricity on the formed surface is sufficient, and the electromagnetic conversion characteristics are further improved.

It is preferable that the film of the present invention is oriented in one direction and then stretched in the same direction (re-horizontal stretching) to strengthen orientation and then heat-treated.・ The protrusions become more uniform due to the heat treatment.
It is desirable because it can be miniaturized. Next, the production method of the present invention will be described, but is not limited thereto.
First, the polyester pellets polymerized by a conventional method are sufficiently dried, and then supplied to a known extruder, preferably a melt extruder having a compression ratio of 3.8 or more, and a temperature at which the pellets are melted and a temperature at which the polymer is decomposed. It is melt-extruded in a sheet form from a slit die at the following temperature, and cooled and solidified to form an undrawn sheet. At this time, the intrinsic viscosity of the unstretched sheet is desirably 0.5 or more from the viewpoint of film properties.
Next, the unstretched sheet is heated at 70-120 ° C for 2.0-5.
On a 0-stretched film, a coating agent prepared by preparing the shell core structure particles of the present invention in a predetermined amount is applied, and the coating film is dried to form a predetermined coating layer. .
Stretch 0 times horizontally. Further, if necessary, the film may be re-laterally stretched. Further, the biaxially oriented film has a
Heat-treat for 1 to 60 seconds while giving 10% to 10% relaxation. The coating method is not particularly limited, but a gravure coating method, a reverse coating method, a kiss coating method, and a water-dispersed coating agent can be used because a thin film coating can be performed at a high speed. It is preferable to apply a known method such as a die coating method or a metaling bar coating method. At this time, a known surface treatment such as a corona discharge treatment in the air or other various atmospheres may be performed on the film, if necessary, before coating. By this surface treatment, not only the coating property is improved, but also the projections can be formed more firmly on the film surface. The concentration of the coating agent and the conditions for drying the coating film are not particularly limited, but the drying conditions for the coating film are preferably performed within a range that does not adversely affect the properties of the polyester film. In order to obtain the projections of the present invention, the amount of coating on the laminated film after the heat treatment is 0.0001 to 0.05 g / m ² , preferably 0.0005 to 0.03 g / m ² , more preferably 0.1 to 0.05 g / m ² .
The range of 001 to 0.01 g / m ² is desirable. If the coating amount is 0.0001 g / m ² or less, it may be difficult to provide sufficient lubricity due to a small number of projections, and 0.05 g / m ^2.
If m ² or more, the projections have a film forming property, and it may be difficult to form the projections. As described above, the laminated polyester of the present invention can be produced, and a ferromagnetic thin film type magnetic recording medium can be produced by providing a ferromagnetic thin film layer on the projection forming surface of the laminated polyester. Here, the ferromagnetic thin film refers to a ferromagnetic metal such as iron, cobalt, and nickel, or Fe—Co, Fe—Ni, F
e-Rh, Fe-Cu, Fe-Au, Co-Cu, Co
-Au, Co-Y, Co-La, Co-Pr, Co-G
d, Co-Sn, Co-Pt, Ni-Cu, Fe-Co
-A magnetic alloy such as Nd, Mn-Bi, Mn-Sn, Mn-Al is formed on a film by a vacuum deposition method, an ion plating method, a sputtering method, an ion beam deposition method, an electrolytic deposition method, an electrolytic plating method, or the like. It is formed. The ferromagnetic thin film applied to the laminated polyester film of the present invention may be of course any one produced by any of the methods described above, but the deposition direction is inclined in the longitudinal direction (90 ° to 30 °) and It is preferable to use a material which is not inclined and which is deposited at 1 × 10 ⁻⁴ Torr while introducing O ₂ or O ₂ and Ar as an atmosphere. The thickness of the ferromagnetic thin film is usually 0.01 to 1
μm, preferably 0.05 to 0.3 μm is used. As described above, since it is excellent in transparency, lubricity, smoothness, easy adhesion, and the like, it is suitable for magnetic materials, graphics, photographic films, packaging films, tracings, electric insulating materials, and the like.

[0034]

[Measurement method] The method for measuring the characteristics and the method for evaluating the effect in the present invention are as follows.

(1) Coating Layer Thickness Using a transmission electron microscope model HU-12 manufactured by Hitachi, Ltd., an ultra-thin section of the laminated film is observed to determine the thickness.

(2) Surface roughness (root mean square roughness) Atomic force microscope NanoScope manufactured by Digital Instruments
Mean square roughness (standard deviation when fitting a plane, unit nm) under the following conditions using an IIAFM D head
Was measured.

Tip: SiN cantilever-integrated needle {Nano Probes} Scanning mode Constant force mode (Topographic mode) Scanning range 5 μm × 5 μm Scanning speed 0.69 Hz Measurement environment Room temperature, air (3) Slipperiness (static friction coefficient μs, dynamic friction coefficient μk) The coefficient of friction between films is ASTM-D-1894.
The coefficient of static friction μs was measured in accordance with Example No. 63. Generally, the range in which the lubricity is excellent is 1.6 or less in μs, preferably 1.2 or less.

Dynamic friction coefficient μk between film and metal post
Is measured using a kinetic friction coefficient meter (TBT-300, manufactured by Yokohama System Research Institute) at 25 ° C. and 50% relative humidity in an atmosphere of coating surface or ferromagnetic thin film-formed surface.
After contacting a SUS420J2 mmφ post with a surface roughness of 0.2S at a winding angle of 180 ° and moving it at a speed of 3.3 cm / sec, the tension is controlled so that the entry side tension T1 becomes 25 g. Then, the dynamic friction coefficient μk is calculated from the value (g) of the output side tension T2 by the following equation.

Μk = (2 / π) ln (T2 / T1) = 0.637ln (T2 / T1) (4) Easy adhesion Bell jar type high vacuum vapor deposition apparatus (E made by Nihon Vacuum Engineering Co., Ltd.)
(BH-6 type) and a commercial cellophane tape manufactured by Nichiban Co., Ltd. is adhered to the aluminum deposition surface at a degree of vacuum of about 1 × 10 −5 mmHg, and a pressure of about 5 kg is applied using a hand roller. Thereafter, the evaluation was performed on the remaining aluminum adhered surface after forcible peeling in the 180 ° direction. Evaluation criteria are:
Very good when the remaining deposited area of the aluminum deposited film layer is 95% or more (（), good when 90% or more and less than 95% (○), 7
5% or more and less than 90% were slightly inferior (△), and less than 75% were poor (x). The larger the remaining adhesion area, the better the adhesiveness.

(5) Number and Shape of Granular Protrusions Using an FE-SEM (electron emission type scanning electron microscope, manufactured by Hitachi, Ltd., model S-800), an accelerating voltage of 10K was used.
V, a photograph was taken at a sample inclination angle of 30 °, the number of granular projections was counted, and the number of projections per mm ² was calculated by area conversion.

The height, average roughness, average depth, maximum roughness and the like of the protrusions were measured using a non-contact three-dimensional fine shape measuring device ET-30HK manufactured by Kosaka Laboratory Co., Ltd. (6) Height of protrusion and diameter of protrusion Atomic force microscope (AFM) (NanoScope II AFM De)
gital Instruments), the height of the protrusion, the diameter of the protrusion, the root mean square roughness, the maximum and minimum roughness, and the like were calculated.

(7) Thickness of Magnetic Layer In the case of a magnetic layer formed by vacuum evaporation, sputtering, or the like, a fluorescent X-ray minute portion film thickness meter STF-15 manufactured by Daini Seikosha Co., Ltd.
6 was measured. (Nm) (8) Void fraction TEM (transmission electron microscope, H-600 manufactured by Hitachi, Ltd.)
Using a mold and an accelerating voltage of 100 Kv), the cross section of the projection of the section in the stretching direction was observed by the ultra-thin section method. In this case, the void ratio was expressed as V = S / T (%). In addition, this value was represented as an average value of n = 5.

(9) Running Durability Using a tape running tester SFT-700 (Yokohama Systems Research Institute Co., Ltd.), a film obtained by slitting a film into a tape having a width of 1/2 inch was used. The friction coefficient μK1 at the time of running 50 times repeatedly at 20 ° C. in a 60% RH atmosphere and the initial friction coefficient μK1 was obtained from the following equation.

ΜK = (2 / π) ln (T2 / T1) ΔμK = μK50−μK1 Here, T1 is the incoming tension (50 g), and T2 is the outgoing tension. Guide diameter is 6mmφ, guide material is SUS
27 (surface roughness 0.2 S), winding angle 90 °, running speed 3.3 cm / sec. When ΔμK obtained by this measurement is less than 0.03 (◎), when it is 0.03 or more and less than 0.04 (、), when it is 0.04 or more and less than 0.06 (△), When it exceeded 0.06, it was judged as (x). (10) Electromagnetic conversion characteristics When the output signal when reproducing the sample magnetic recording medium is viewed on one screen, a signal with a strong output signal and a flat signal waveform (good) and a weak output signal Those having a deformed signal waveform were determined to be (defective).

(11) Abrasion resistance The laminated polyester film is 25 to 30 cm long and 1 width wide.
/ 2 inch, when the laser blade is run at an angle of 90 ° to the surface of the coating layer, a depth of 0.5 mm, and a load of 500 g / 0.5 inch at a speed of 6.7 m / sec. The width in the depth direction of the shaving powder adhering to the laser blade was determined by microphotographing (× 160). When the width in the depth direction of the shavings is less than 2 μm (◎), 2 μm or more 3
Less than μm (μ), 3 μm or more and less than 5 μm (△), 5
μm or more was defined as (×). It goes without saying that the smaller the adhesion depth of the shaving powder, the better the shaving property.

(12) Transparency (Haze) of Film Measured by Haze Meter-SEP-H-2 by Nippon Seimitsu Kogaku Co., Ltd. according to JIS-K-6714.

(13) Glass transition temperature The glass transition temperature of the projection-forming resin is determined by a differential scanning calorimeter (PE).
RKIN ELMERDSC-2 type (PERKINE
LMER))) at a heating rate of 10 ° C./min.

[0048]

【Example】

Example 1 A homopolymer chip of 0.8% solution haze of polyethylene phthalate (intrinsic viscosity = 0.62) containing as little as possible internal particles and inert particles based on the residue of a polymerization catalyst and the like produced by a conventional method. Melting point: 259 ° C) to 180 ° C.
For 2 hours under reduced pressure (3 mmHg). 280 ℃
Is supplied to an extruder having a screw with a compression ratio of 3.8 at T
Melt extrusion from mold die, surface temperature 2 using electrostatic application method
After being wound around a cooling drum at 0 ° C. to be cooled and solidified to form an unstretched film, the obtained film was stretched 3.5 times in the longitudinal direction by roll stretching at 90 ° C., and the surface was subjected to corona discharge treatment. Later, the core part is made of crosslinkable acrylic,
Shell core structure particles (solid content: 30% by weight, average particle diameter: 65 nm, shell / core ratio = 1/1 (weight ratio), shell Tg = 0 ° C., core Tg = 75 ° C.) having a shell portion of thermoplastic acrylic Further, the mixture is diluted with pure water to obtain a solid content of 0.1%.
A 15% by weight coating was prepared. This coating material is applied to one surface of the uniaxially stretched film by a metalling bar coating method, and then stretched 3.6 times in the horizontal direction at 100 ° C. while drying the coating layer. After redrawing 5%,
Heat treatment at 225 ° C for 5 seconds while relaxing 2% in the lateral direction,
Coating amount in laminated film after heat treatment 0.005 g /
Thus, a laminated polyester film having a thickness of 12 μm on which m ² was laminated was obtained. The properties of the laminated polyester film are shown in Tables 1 and 2. Then, a Co-Ni alloy (Ni 20% by weight) was added to the film by an electron beam evaporation method.
500 angstrom oblique deposition was performed. A perfluoropolyalkyl ether metal salt in which trichlorotrifluoroethane was dispersed was deposited on the vapor deposition surface of the vapor deposition film at a solid content of about 3%.
0 mg / m ² , and a mixture of polyisocyanate containing alkyl phosphate, polyurethane and ditrocellulose on the back surface of the film so that the thickness after drying becomes 0.8 μm. After forming a magnetic layer, the magnetic tape is slit into a half-inch width.
Got Table 2 shows the results of evaluating the magnetic tape characteristics.

Example 2 On the basis of Example 1, a laminated polyester film was obtained in which the same coating agent as in Example 1 was laminated at a coating amount of 0.003 g / m ^{2 on} the laminated film after heat treatment. Next, a magnetic tape was obtained after oblique deposition in the same manner as in Example 1.
The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2. As shown in Tables 1 and 2, when the laminated polyester film is within the range of the present invention, a magnetic recording medium having good running properties, particularly, durability of repeated running and good electromagnetic conversion properties can be obtained. It can be seen that out of the range (Comparative Examples 1 to 4), it is impossible to obtain a magnetic recording medium having all the excellent characteristics.

Example 3 On the basis of Example 1, a laminated polyester film was obtained in which the same coating agent as in Example 1 was used to laminate the heat-treated laminated film at a coating amount of 0.001 g / m ² . Thereafter, a magnetic tape was obtained in the same manner as in Example 1. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Example 4 On the basis of Example 1, instead of the coating material of Example 1, the polymer in the core was styrene / vinyl benzene / ethylene phenyl benzene = 45.
/ 50/5% shell / core structure particles composed of highly crosslinked polymer and shell polymer composed of acrylic (solid content concentration 10% by weight, average particle diameter 26 nm, shell / core ratio = 1.5 /
1.0 (diameter ratio), shell Tg = 20 ° C.) was further diluted with pure water to prepare a coating having a solid content of 0.1% by weight. Otherwise, a laminated polyester film was obtained in exactly the same manner as in Example 1. The coating amount on the laminated film after the heat treatment was 0.0026 g / m ² . Thereafter, a magnetic tape was obtained in the same manner as in Example 1. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Example 5 A laminated polyester film having a coating amount of 0.0013 g / m ² in a laminated film after heat treatment was carried out in exactly the same manner as in Example 4 except that the coating agent concentration in Example 4 was changed to 0.05% by weight. Thus, a magnetic tape was obtained in the same manner as in Example 4. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Example 6 A laminated polyester film was obtained in exactly the same manner as in Example 4 except that the shell polymer was changed to a polyester copolymer while the core polymer of Example 4 was kept as it was. The coating amount in the laminated film after the heat treatment is 0.0026 g /
m ² . Thereafter, a magnetic tape was obtained in the same manner as in Example 1. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Example 7 Based on Example 4, the concentration of the coating agent used in Example 4 was set to 0.015% by weight (solid content), and a surfactant (Newrex R manufactured by NOF Corporation) was used. ) At 0.15% by weight (solid content) and a silane coupling agent (Shin-Etsu Chemical Co., Ltd.)
A laminated polyester film was obtained in exactly the same manner as in Example 4 except that 0.01% by weight (solid content) of KBM603) was added. The coating amount on the laminated film after the heat treatment was 0.00038 g / m ² . Tables 1 and 2 show the properties of the laminated polyester film and the magnetic tape.
It was shown to.

Example 8 A homopolymer chip of 0.8% solution haze of polyethylene phthalate (intrinsic viscosity =) containing as little as possible no internal particles and no inert particles based on the residue of a polymerization catalyst produced by a conventional method. 0.62, melting point: 259 ° C) to 180 ° C
For 2 hours under reduced pressure (3 mmHg). 280 ℃
Is supplied to an extruder having a screw with a compression ratio of 3.8 at T
Melt extrusion from mold die, surface temperature 2 using electrostatic application method
After being wound around a cooling drum at 0 ° C. to be cooled and solidified to form an unstretched film, the obtained film was stretched 3.5 times in the longitudinal direction by roll stretching at 90 ° C., and the surface was subjected to corona discharge treatment. Later, the core part is made of crosslinkable acrylic,
Shell core structure particles (solid content: 30% by weight, average particle diameter: 65 nm, shell / core ratio = 1/1 (weight ratio), shell Tg = 0 ° C., core Tg = 75 ° C.) having a shell portion of thermoplastic acrylic Further, the mixture is diluted with pure water to obtain a solid content of 0.1%.
A 15% by weight coating was prepared.

Further, 87.5 mol% of terephthalic acid, 5
A water-soluble copolyester consisting of 12.5 mol% of sodium sulfoisophthalic acid, 94 mol% of ethylene glycol as a glycol component and 6 mol% of diethylene glycol is dissolved in water to obtain a solid content of 0.5% by weight. % Of the coating was prepared. The shell core particles having a solid content concentration of 0.15% by weight and the water-soluble copolymerized polyester having a solid content concentration of 0.5% by weight were sampled at a weight ratio of 1: 1. did.

After this coating material was applied to one surface of the uniaxially stretched film by a metalling bar coating method, the coating layer was stretched 3.6 times in the transverse direction at 100 ° C. while drying, and further 2 times.
After 5% re-stretching in the transverse direction at 00 ° C., heat-treated at 225 ° C. for 5 seconds while relaxing in the transverse direction by 2%, and the applied amount in the laminated film after the heat treatment was 0.017 g / m ^2. A laminated polyester film having a thickness of 12 μm was obtained.
Table 1 and Table 2 show the properties of the laminated polyester film.
It was shown to. Next, a Co-Ni alloy (Ni 20% by weight) was obliquely vapor-deposited on the film by an electron beam evaporation method at 1500 angstrom. A perfluoropolyalkyl ether metal salt in which trichlorotrifluoroethane is dispersed is applied at a solid content of about 30 mg / m ^{2 on} the vapor deposition surface of the vapor deposition film, and a polyisocyanate containing an alkyl phosphate ester is further applied to the back surface of the film. Of the mixture consisting of polybutadiene, polyurethane and ditrocellulose to a thickness of 0.8 μm after drying.
m to form a back coat layer.
A magnetic tape was obtained by slitting to a 1/2 inch width. Table 2 also shows the results of evaluating the magnetic tape characteristics.

Example 9 On the basis of Example 1, instead of the coating composition of Example 1, the polymer in the core portion was styrene / vinylbenzene / ethylenevinylbenzene = 45.
/ 50/5% shell / core structure particles composed of highly crosslinked polymer and shell polymer composed of acrylic (solid content concentration 10% by weight, average particle diameter 26 nm, shell / core ratio = 1.5 /
1.0 (diameter ratio), shell Tg = 20 ° C.) was further diluted with pure water to prepare a coating having a solid content of 0.1% by weight.

Further, 87.5 mol% of terephthalic acid, 5
A water-soluble copolyester consisting of 12.5 mol% of sodium sulfoisophthalic acid, 94 mol% of ethylene glycol as a glycol component, and 6 mol% of diethylene glycol is dissolved in water to give a solid concentration of 0.7% by weight. % Of the coating was prepared. The coating material of the present invention was obtained by collecting 1: 1 by weight of the shell core particles having a solid content concentration of 0.15% by weight and the water-soluble copolymer polyester having a solid content concentration of 0.7% by weight and blending well.

Otherwise, a laminated polyester film was obtained in exactly the same manner as in Example 1. The coating amount on the laminated film after the heat treatment was 0.02 g / m ² . Thereafter, a magnetic tape was obtained in the same manner as in Example 1. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Example 10 Shell core structure particles (solid content) in which the polymer in the core portion of Example 3 was composed of a highly crosslinked polymer of styrene / vinylbenzene / ethylenevinylbenzene = 45/50/5%, and the polymer of the shell portion was acrylic. Concentration 10% by weight, average particle diameter 26 nm, shell / core ratio = 1.5 / 1.0 (diameter ratio), shell Tg = 2
0 ° C.) was further diluted with pure water to prepare a coating having a solid content concentration of 0.015% by weight.

Further, 87.5 mol% of terephthalic acid, 5
-85% by weight of a copolymerized polyester consisting of 12.5 mol% of sodium sulfoisophthalic acid, 94 mol% of ethylene glycol as a glycol component and 6 mol% of diethylene glycol, and polyethylene glycol (molecular weight: 600)
A water-soluble copolymerized polyester containing 15% by weight was dissolved in water to prepare a coating having a solid content of 0.5% by weight.
Shell core particles having a solid content of 0.015% by weight and polyethylene glycol 15% by weight having a solid content of 0.5% by weight
The contained water-soluble copolymerized polyester was collected at a weight ratio of 1: 1 and well blended to prepare a coating composition of the present invention. Otherwise, a laminated polyester film was obtained in exactly the same manner as in Example 1. The coating amount in the laminated film after the heat treatment is 0.01
It was 3 g / m ² . Hereinafter, similarly to the first embodiment, the magnetic tape
Got The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2.

Comparative Example 1 As a coating agent, styrene / divinylbenzene / 0.1 μm in diameter was used.
Exactly the same as in Example 1 except that an aqueous dispersion of organic particles of ethylene vinylbenzene = 45/50/5% was added in an amount of 0.3 part by solid content with respect to 100 parts by weight of the solid content of the thermoplastic acrylic resin. The coating amount in the laminated film after heat treatment is 0.00
3 g / m ² laminated polyester film and magnetic tape
Got The properties are as shown in Tables 1 and 2. Since the particles outside the present invention were used, the projections formed were likely to fall off and the film was poor in smoothness. The magnetic tape characteristics were not good either.

COMPARATIVE EXAMPLE 2 The same amount of the thermoplastic acrylic resin as used in Comparative Example 1 was used, and the coating amount of the heat-treated laminated film was 0.0
A laminated polyester film and a magnetic tape were obtained in the same manner as in Example 1 except that the amount was changed to 6 g / m ² . Table 1 shows the characteristics
The results are shown in Table 2 and Table 2. As a result, the film was inferior in slipperiness without protrusions and had poor magnetic tape characteristics.

Comparative Example 3 The same procedure as in Example 1 was repeated except that the coating amount in the laminated film after the heat treatment was changed to 0.06 g / m ^{2 using} the same coating agent as in Example 1. A polyester film was obtained. Laminated polyester film and magnetic tape
The characteristics of the tapes are shown in Tables 1 and 2. However, since no protrusions were formed, the slipperiness was poor, and it was not possible to obtain a magnetic recording medium excellent in each property.

Comparative Example 4 Based on Example 1, the amount of coating on the laminated film after heat treatment with the same coating agent as in Example 1 was 0.00005 g / m 2.
^A laminated polyester film was obtained in the same manner as in Example 1 except that the film was set to 2. The properties of the laminated polyester film and the magnetic tape are shown in Tables 1 and 2. As a result, the number of projections was very small and the film had poor slipperiness. .

[0067]

[Table 1]

[Table 2]

[0068]

The film of the present invention has surface projections based on particles having a shell-core structure in which the outside is softer than the inside, so that the film is excellent in transparency, smoothness and lubricity. Further, by including the protrusions with a water-soluble polyester copolymerized polyester, it is excellent in abrasion resistance and running durability.

Continuation of front page (56) References JP-A-3-297646 (JP, A) JP-A-3-292334 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 27 / 36 C08J 7/04 C09D 1/00-201/10

Claims (7)

(57) [Claims] On at least one surface according to claim 1 polyester film, laminated with a projection outside from the inside consists of particles of soft shell core structure 1 × 10 ⁶ cells / mm ² or more polyester
A core portion of the particles having the shell-core structure.
Acrylic or styrene / divinylbenzene is crosslinkable
A laminated polyester film comprising a polymer containing a copolymer as a main component . 2. At least one surface of a polyester film is provided with a projection composed of particles of the above-mentioned shell core structure, whose exterior is softer than the interior, and a water-soluble copolyester.
^{2. The} film according to claim 1, wherein the number of particles is at least ⁶ / mm ^2.
Laminated polyester film. 3. A laminated polyester film according to claim 1 or 2 shell portion of the particles of the shell core structure is characterized in that it consists of a thermoplastic polymer. 4. A void cross-sectional area which can be around the core portion of the projection, laminated polyester film according to claim 1, characterized in that more than 10% of the cross-sectional area of the core portion. 5. The upper carboxymethyl E Le portions thermoplastic acrylic polymer
Or a polyester.
5. The laminated polyester film according to any one of items 4 to 4. 6. The laminated polyester film according to claim 2 , wherein the water-soluble copolymerized polyester contains a polyoxyalkylene glycol component in an amount of less than 40% by weight. 7. The laminated polyester according to claim 2 , wherein a solid content ratio of the shell core structure particles and the water-soluble copolymerized polyester is in a range of 95/5 to 5/95. the film.