JPH02107642A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the title film having a coating film containing a condensing inorganic fine particle and water soluble or water dispersible acryl resin and epoxy modified silicone on at least one surface of polyester film and excellent in slip properties, mold release characteristics and abrasion resistance. CONSTITUTION:Undrawn polyester film, preferably consisting of polyethylene terephthalate is drawn in the longitudinal direction to afford a monoaxially oriented film. The film is subjected to corona discharge treatment under carbon dioxide atmosphere and then a mixture consisting of a condensing inorganic fine particle (e.g. antimony sol) subjected to heat treatment at >=180 deg.C for 1-10sec, water soluble or water dispersible acryl resin and water soluble or water dispersible epoxy modified silicone is applied to the treated film face and the coated film is heated to 90-130 deg.C and drawn in the width direction and further heat-treated at 180-240 deg.C for 1-10sec to relax in the width direction and cooled to provide the aimed film. Furthermore, thickness of the mixture applied to the film surface is preferably 0.02-1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a 2'l'lll oriented polyester film. Specifically, the present invention relates to a 2IIIll oriented polyester film that has excellent slipperiness, mold releasability, and abrasion resistance.

[Prior Art] Biaxially oriented polyester has excellent mechanical properties, dimensional stability, and heat resistance, so it is used in many applications such as magnetic recording materials, packaging materials, graphic arts materials, and information recording materials. Widely used as a base film.

However, polyester film is used in fields that require easy slipping and release properties, such as preventing sticking of thermal transfer foil in thermal transfer printers, and tenor sheets for audio cassette adhesives (friction, temporary).

It is known that a coating layer is provided in back coats for magnetic tapes to provide slipperiness and mold release properties. slipperiness,
As a polyester film imparted with mold releasability (4), one is known in which a mixed layer of an aqueous polymer and (1) lubricant is coated on one side of the film (Japanese Unexamined Patent Publication No. 1982-19268M).

[Problems to be Solved by the Invention] However, the abrasion resistance of the coating layer deteriorates due to the addition of a lubricant to the polyester film that has been imparted with the slipperiness and mold releasability described above, making it difficult to open and close as described below. I was awake.

(1) Thermal transfer foil is a thin polyester film with a coloring material layer (thermal melting part or heat sublimation ink layer) applied to one side, and a coloring material layer (thermal melting part or heat sublimation ink layer) applied to the other side to prevent the thermal head from sticking to the foil. For this reason, a hot stick prevention layer is provided.If the hot stick prevention layer has poor wear resistance, the hot stick prevention layer will be scraped off during running and adhere to the thermal head, causing problems such as poor printing.

In other words, the principle of thermal transfer is that heat supplied from the thermal head is transmitted to the thermal transfer foil, and the ink layer on the surface is transferred onto the recording paper to record images and characters.
The scraped material adhering to the surface of the thermal head impedes heat transfer to the thermal transfer foil, resulting in areas where ink is not transferred or where the ink is thin, where ink should normally be transferred.

In addition, the thermal head may corrode due to thermal decomposition products from the scraped hot stick prevention layer attached to the thermal head.
Problems such as damage may occur.

(2) Audio cassette tapes have a retainer sheet (friction plate) attached to the inside of the case that stores the tape, and when the tape is running, the side of the tape wound on the reel comes into contact with the retainer sheet. By rotating the reel while rotating, the tape runs smoothly and prevents uneven winding of the tape wound on the reel. For this reason, the retainer sheet is required to have easy sliding properties, and the polyester film is provided with an easy slipping layer. If the slippery layer does not have wear resistance, scraping will occur due to contact with the tape. The scrapes get caught up in the tape and adhere to the magnetic surface, causing recording signal dropouts and clogging of the magnetic head.

(3) The back coat layer of a magnetic tape is also required to be slippery, but if it is not abrasion resistant, the back coat layer will be scraped off by guide pins etc. while the tape is running, and the scraped material will be on the magnetic surface (4). This causes recording signal dropouts and magnetic head clogging.

The present invention solves the drawbacks of these conventional techniques, and provides two materials with excellent slipperiness and mold releasability, as well as excellent RT abrasion resistance.
An axially oriented polyester film is provided.

[Means for Solving the Problems] The present invention provides at least one side of a polyester film,
It is based on a biaxially oriented polyester film characterized by having a coating containing condensable inorganic fine particles, a water-soluble or water-dispersible acrylic resin, and a water-soluble or water-dispersible epoxy-modified silicone.

The polyester film referred to here is a general term for polymers having ester bonds as the main bond chain in the main chain, and particularly preferred polyesters include polyethylene terephthalate, polyethylene 2,6-naphthalate, polyethylene α-, β-bis (2-chlorophenoxy)ethane 4,
These include 4°-dicarboxylate, polybutylene terephthalate, etc. Among these, polyethylene terephthalate is the most preferable when quality, economical efficiency, etc. are comprehensively considered. Therefore, hereinafter, polyethylene terephthalate will be described as a representative polyester.

Polyethylene terephthalate (hereinafter referred to as i&P) in the present invention
It is abbreviated as ET. ) is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 9
The content is 5 mol% or more or ethylene terephthalate is used repeatedly. Note that a part of the acid component and/or glycol component can be replaced with a third component as described below.

- Acid component isophthalic acid, 2,6-naphthalene dicarboxylic acid, 1.
5-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4゜4
-diphenylsulfonedicarphonic acid, 4,4''-diphenyletherdicarboxyethoxybenzoic acid, adipic acid, azelaic acid, cepacic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, ε-oxycaproic acid, trimellitic acid,
Trimesic acid, pyromellitic acid, α,β-bisphenoxyethane-4,4′-dicarboxylic acid, α,β-bis(2
-Chlorphenoxy)ethane-4,4°-dicarboxylic acid, 5-sodium sulfoisophthalic acid glycol component - Propylene glycol, butylene glycol, hexamethylene glycol, decamethylene glycol, neobenzene gelicol, 1,1-cyclohexane dimeta Tool, 1,4-cyclohegysan dimethanol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl)sulbone,
Diethylene glycol, triethylene glycol, pentaerythritol, trimethylolpropane, polyethylene glycol, etc.

In addition, known additives such as heat-resistant stabilizers, oxidation-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or grain-free fine particles, and fillers are added to this PET. , a mold release agent, an antistatic agent, a nucleating agent, etc. may be added.

The intrinsic viscosity of PET as described above (measured in orthochlorophenol at 25°C) is preferably 0.40 to 1.20, more preferably 0.50 to 0.80, and even more preferably 0. It is in the range of .55 to 0.75 dl/g.

Next, what is a normal 2IlII oriented polyester film?
It is made by stretching an unstretched polyester sheet or film in the longitudinal direction and the width direction, so-called biaxial directions, and shows a biaxial orientation pattern in wide-angle X-ray diffraction.

The condensable inorganic fine particles as used in the present invention are inorganic fine particles having condensation reactivity, such as antimony sol, zirconia sol, titania sol, and silica sol. In particular, a colloidal solution of high molecular weight silicic anhydride has a particle size of 10 to 20
The particle surface has -OH groups at 0 mμ, and when mixed with a reactive resin, the functional groups of the resin, such as -OH groups, -
It is preferred because it easily reacts with COOH groups, -CH20H groups, epoxy groups, etc. by hlI heat.

The water-soluble or water-dispersible acrylic resin (hereinafter abbreviated as acrylic resin) as used in the present invention is one whose main component is alkyl acrylate or alkyl acrylate, and the component is 30 to 99 mol%, A water-soluble or water-dispersible resin that is copolymerizable with these resins and contains 70 to 1 mol % of a vinyl monobase component having a functional group is preferred.

The reason why the content of alkyl acrylate or alkyl methacrylate in the acrylic resin is preferably 30 mol % or more is because it improves coating formation properties, coating film strength, and blocking resistance. Alkyl acrylate or argyl methacrylate in acrylic resin is 99 mol%
It is preferable to do the following by introducing a compound having a specific functional group into the acrylic resin as a joint component to make it easier to water-solubilize and water-disperse it, and to keep the state stable for a long period of time. This is because of the improved adhesion between the coating layer and the polyester film layer, and the strength of the coating layer due to the reaction within the coating layer.

This is because chemical resistance can be improved.

Examples of alkyl groups in alkyl acrylates and alkyl methacrylates include methyl group, ethyl group, 1. n-
Examples include propyl group, isopropyl Il, Q-butyl group, isobutyl I, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, and cyclohexyl group.

Further, an acrylic resin having a functional group can be obtained by copolymerizing a vinyl monomer having the functional group with an alkyl acrylate or an alkyl methacrylate. Examples of the acrylic resin having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, itaconic acid, maleic acid, and fumaric acid.

Crotonic acid, metal salts of these carbonic acids with mono- to lithium, an-E nium salts, or maleic anhydride are copolymerized. Especially acrylic acid.

Maleic acid, itaconic acid, etc. are preferred from the viewpoint of reactivity. Examples of acrylic resins having hydroxyl groups include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, and β-hydroxyethyl acrylate.
Hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, etc. are copolymerized. In particular, hydroxyethyl acrylate, I-nitroxyvinyl acrylate, etc. are preferred from the viewpoint of reactivity. Examples of the acrylic resin having an alkylol group include diethylaminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-aminobutyl vinyl ether, and dimethylaminoethyl methacrylate-1.

Methylolated amine groups such as dimethylaminoethyl vinyl ether, or methylolated amide groups such as acrylamide, methacrylamide, N-methyl methacrylamide, ureido vinyl needles, β-ureido isobutyl vinyl ether, and ureitoedyl acrylate. Copolymerizes methylolated acrylamide, methylolated acrylamide, methylolmethacrylamide, etc. In particular, methylol methacrylamide, methylol acrylamide, etc. are preferred from the viewpoint of reactivity. The acrylic resin having an epoxy group is copolymerized with a vinyl monomer having an epoxy group, and glycidyl methacrylate, glycidyl acrylate, etc. are particularly preferred from the viewpoint of reactivity. Furthermore, the following compounds may be used in copolymerization with vinyl monomers having these functional groups. Namely, acrylonitrile, methacrylonitrile, styrenes, butyl vinyl ether, maleic acid mono- or dialkyl ester, fumaric acid-sino- or dialkyl ester,
Itaconic acid mono- or dialkyl ester, methyl vinyl ketone, vinyl chloride, vinylidene chloride vinyl acetate,
Examples include, but are not limited to, vinylpyridine, vinylpyrrolidone, vinyltrimethoxysilane, and the like.

Acrylic resins containing one or more of the above functional groups are preferable because of their reactivity with condensable inorganic particles, and can provide wear resistance.

The water-soluble or water-dispersible epoxy-modified silicone as used in the present invention includes, for example, an epoxy-modified silicone emulsion, an epoxy polyether-modified silicone, and the like.

In particular, epoxy polyether-modified silicone is preferred in terms of mechanical stability and compatibility with acrylic resin.

In the present invention, the epoxy-modified silicone has good slipperiness,
Provides mold release properties, reacts with acrylic resin and condensable inorganic particles, provides wear resistance, and prevents the epoxy-modified silicone itself from falling off.

A mixture of the above-mentioned condensable inorganic particles, a water-soluble or water-dispersible acrylic resin, and a water-soluble or water-dispersible epoxy-modified silicone is coated on the film, and this coating consists of five layers. The composition ratio of the condensable inorganic fine particles, acrylic resin, and epoxy-modified silicone is in the range of 5 to 120, particularly 10 to 100, when the acrylic resin is 100 by weight. Moreover, it is preferable from the viewpoint of slipperiness and mold releasability, and it is preferable that the condensable inorganic fine particles are in the range of 0.1 to 50, particularly 1 to 40.

In the present invention, a surfactant or the like may be added to the coating solution for the purpose of improving the coating properties on polyester films.

In the present invention, a crosslinking catalyst, for example, Nt-141-+2PO4, is used to accelerate the reaction and improve wear resistance.
.

J: Yes, even if Zn (NO3)2 or the like is added. In particular, N
The reaction can be greatly accelerated by adding H4H2PO4.

The mixture layer (before being applied to the film) has a thickness of 180'
It is desirable that the material is heat treated at a temperature of C or higher, preferably 200C or higher for 1 to 10 seconds. Due to being subjected to such high temperature thermal history, it becomes slippery.

Mold releasability and wear resistance are greatly improved. Such high-temperature heat treatment is extremely difficult with the usual coating method of applying a coating material to a biaxially oriented polyester film and subjecting it to dry heat treatment (the film used in the present invention usually has a
The thickness is about 10t, tm, and it is extremely thin, so 18
When high temperatures such as 0'C or higher are applied, the film shrinks and becomes wrinkled. ). Therefore, in the process of producing a biaxially oriented polyester film, it is preferable to apply the above mixture to bb, then stretch and heat treat it. With this method, high-temperature heat treatment of 180°C or higher, preferably 200°C or higher, can be carried out without any problem. The thickness of the above mixture applied to the back surface of the film is desirably in the range of 0.01 to 2 .mu.m, preferably 0.02 to 1 .mu.m.

If the thickness is too thin, it will be slippery.

It has poor mold releasability and abrasion resistance, and if it has a certain thickness, it does not need to be thicker than that.

Next, a specific example of the method for producing a 2I14I oriented polyester film of the present invention will be described. PFT containing so-called precipitated particles and inorganic fine particles (for example, colloidal silica with a particle size of 1 μm) precipitated during the polymerization process is dried and melt-extruded according to a conventional method, and the extruded sheet-like melt is cooled and solidified to form an unstretched material. Make PET film. 80% of this film
It is heated to ~120'C and stretched 2.5 to 5 times in the longitudinal direction to form a uniaxially oriented film. One side of this film is subjected to corona discharge treatment in a carbon dioxide atmosphere, and this treated side is
A coating solution containing a mixture of condensable inorganic fine particles, a water-soluble or water-dispersible acrylic resin, and a water-soluble or water-dispersible epoxy-modified silicone is applied.

Next, the coated film is stretched 3 to 4.5 times in the width direction while being heated to 9Q to 130°C, and subsequently introduced into a heat treatment zone at 180 to 240'C to
Heat treat for ~10 seconds. During this heat treatment, 3~
It is better to do a 12% relaxation treatment. The heat-treated film is gradually cooled through an intermediate cooling zone, and when it reaches room temperature, it is wound up with a winder to form a mill roll. Next, pass this mill roll through a slitter to achieve the desired width.
Long film product rolls.

When using the film thus obtained as a heat-sensitive transfer foil, a heat-melting or heat-sublimation coloring material layer is applied to the non-coated side, and if necessary, a release layer is roughly applied on top of it. A top coat layer is applied, and then the foil is slit to the required width for a serial mold or line printer to obtain a thermal transfer foil.

When using as a retainer sheet for audio cassette tapes, punch the film into a predetermined shape and attach it to the inside of the cassette case so that the coated side is in contact with the side of the tape wound on the reel.

When used as a magnetic tape, a magnetic material is coated on the uncoated 5 side, and then the tape is slit to the required width for a video tape or the like.

[Method for Measuring Characteristics and Evaluating Effects 1 Methods for measuring characteristics and evaluating effects in the present invention are as follows.

(1) Average surface roughness (Ra) Measured according to J 15-BO6011976. The cutoff diameter was 0.25 mm.

(2) Evaluation of scraping of thermal transfer box Printing was performed using a Nashi video printer GZ-P11 manufactured by Sharp Corporation, and the state of scraping attached to the thermal head was observed under a microscope at 100 times magnification.

The criteria for evaluation were as follows.

No scraping: Good Scraping: Bad (3) Evaluation of retainer sheet scraping Commercially available audio cassette tape (TDK Co., Ltd. AD)
-X90) was equipped with the adhesive retainer sheet of the present invention and run back and forth 100 times on a cassette deck, and the wear of the retainer sheet was observed. The criteria for evaluation were as described above.

No scraping: Good Scraping: Poor [Effects of the invention] A coating solution containing a water-soluble or water-dispersible acrylic resin, a water-soluble or water-dispersible epoxy-modified silicone, and condensable inorganic fine particles is applied to a 21FllI oriented polyester film. As a result, magnetic materials, packaging materials, and information recording materials that use this film as a base material have excellent slipperiness, mold release properties, and abrasion resistance (= It has the effect of eliminating harmful effects.

[Example] Example 1. Example 2 Contains 0.15% by weight of precipitated particles (particles precipitated during the polymerization process) with a particle size of 0.5 to 1.5 μm and 0.2% of calcium carbonate particles with a particle size of 1.5 μm After sufficiently vacuum drying the PFT pellets (intrinsic viscosity 0.63 d/g), they were supplied to an extruder and melt-extruded at 280'C for 10
After filtering through a μm-cut metal sintered filter, it was extruded into a sheet through a T-shaped nozzle, and the sheet was wound around a cooling drum with a surface temperature of 50°C to cool and solidify. In order to improve the adhesion between the sheet and the surface of the cooling drum during this time, a wire electrode was placed on the sheet side, and a DC voltage of 6000 V was applied thereto. Unstretched PET thus jqed
The film was heated to 95°C and stretched 3.5 times in the longitudinal direction to form a 11111 stretched film. One side of this film was subjected to a corona discharge treatment in a carbon dioxide atmosphere, and the water-based paint shown in Table 1 was coated on the treated surface using a rod coating method. This uniaxially stretched film coated on one side was preheated at 98°C, and then stretched 3.9 times in the width direction while heating to 105°C. Next, this film was introduced into hot air at 225°C, tensioned and heat-set for 1 second, allowed to shrink by 8% of the original film width in the width direction in the same temperature atmosphere, and then heated again at the same temperature. Heat set under tension for about 1 second in an atmosphere, and then heat set at 180°C and 150°C.
It is gradually cooled through each zone of 'C and 100'C, finally cooled to room temperature, and then guided to a winder.
It was rolled up and made into a mill roll. Next, this mill roll was passed through a slitter to slit the film to a film width of 600 mm to obtain a film product roll. The thus obtained film with a thickness of about 6 μm has a coating layer of about 0.1 μm coated on one side, and the average roughness of both surfaces is 0.10 μm on the coated surface (measured including the coated layer). Non-coated surface is 0.12μm
Met. A heat-sublimable ink with the following composition is applied to the non-coated side of the film at a dry coating amount of 1 g/bottom, and after drying, it is slit to an appropriate width and a heat-sensitive transfer foil is applied. Had made.

Disperse dye KST-B~136: 4 parts by weight (manufactured by Nippon Kabu) Ethyl hydroxyethyl cellulose 2 6 parts by weight Methyl ethyl ketone: 45 mff 1 part toluene
: 45 small quantity The sample before thermal transfer was applied to a video printer GZ-P11 manufactured by Cisepe Co., Ltd., and 5 sheets of photographic paper were printed with Color Print 1 to 1, and the scraped material deposited on the thermal head (=i) was observed.Thermal head The surface was in good condition with no deposits at all.

Example 3. Example 4 Example 1 except that the film thickness was 25 μm. A film was obtained in exactly the same manner as in Example 2, mounted on an audio cassette, and the tape was run. After the run, the surface of the film Co. 1 was observed, and it was found to be in good condition with no scratches on any of the surfaces.

Comparative example 1. Comparative Example 2 Example 1 and Example 2 except for changing the paint not shown in Table 2
A film was obtained in exactly the same manner. This film was used in Example 1. After inking in exactly the same manner as in Example 2, it was placed on a video printer and the thermal head was observed. Scraping was observed on the surface of the thermal head, indicating that it was defective.

Comparative example 3. Comparative Example 4 Example 3 and Example 4 except for changing the paint shown in Table 2.
A film was obtained in exactly the same manner as above, and the bag layer and tape were run on an audio cassette, and the film coated surface was observed after running. Scraping was observed on the surface of row 1 and was poor.

Claims (2)

[Claims] (1) Biaxial orientation characterized by having a coating containing condensable inorganic fine particles, water-soluble or water-dispersible acrylic resin, and water-soluble or water-dispersible epoxy-modified silicone on at least one side of the polyester film. Polyester film. (2) The water-soluble or water-dispersible acrylic resin is characterized in that it contains one or more types selected from carboxyl groups and their salts, acid anhydride groups, hydroxyl groups, alkylol groups, and epoxy groups. The biaxially oriented polyester film according to claim 1.