TW321665B - - Google Patents

Description

331665 A6 B6 V. Description of the invention (<) The present invention is applied to the magnetic tape used in the cassette of the digital recorder and its biaxially oriented polyester base film. More specifically, tapes that are simpler than cassettes that can be used as recorders for digital recording methods (using fixed heads), such as those used in digital compact cassettes (DCC), will not stretch and deform when used and High-density recording; and its biaxially oriented polyester base film. In recent years, digital audio recorders with excellent sound quality have been developed, as digital recorders (DAT) with rotary head method and digital compact cassette recorders (DCC) with fixed head method. DCC with fixed head method has stable azimuth (direction) The tape guide is set at the top and bottom of the tape to run with a stable tape, and the "azimuth locking pin" is set at each M of the tape pad to obtain higher stability, such as "DCC · MD 6 uid Book" of MURATA Kinya (Denpa Shinbunsha Issue). Specifically, each tape guide has an inclined guide wall, allowing the tape to run when one edge is pushed to the surface of the guide wall, thereby forcing the tape to be in the nickel direction β on the other side. As a result, the tape rotates steadily without being affected in the tape In addition, the locking lock constitutes a structure that reliably keeps the magnetic tape in contact with the magnetic head. Due to this structure, an edge of the magnetic tape running on the inclined wall of the tape guide is forced to stretch by several percent. Therefore, one edge of the tape will stretch, the tape will fold and break the contact between the tape and the magnetic head (head contact). As a result, the recording signal will be lost during the recording time and lost during the playback time ............. ................ ^ ........................ line (please read the precautions on the back before filling in this Page) The paper standard printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs applies the Chinese National Standard (CNS) A4 specifications (210X297 mm). The A6 B6 printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economics ) Insufficient output will make the tape lotus turn unstable. These shortcomings will cause the trouble of not accurately picking up the reproduced signal. Even if there is a high-strength analog tape base film in the longitudinal direction as the DCC base film, it is difficult to prevent the tape from starting. The elongation or deformation of the tape caused by the change in tension at the stop. Furthermore, the above-mentioned base film has insufficient lateral strength. Therefore, it is difficult to prevent the above-mentioned edge damage. In addition, DCC can record high-density recording for digital reproduction and recording, so the surface of the magnetic tape must be relatively flat. The above "DCC · MD Guide Book" describes that the magnetic tape used for DCC should be equivalent to the standard VTR tape, and the surface must be flat. When the digital audio tape has a bottom film (the surface roughness of which is greatly reduced for high-density recording), the lubricity between the film surfaces is poor, and the air between the films is poorly released. Therefore, it is difficult to take out the roll-shaped film. Therefore, the base film must have a flat surface and have excellent running properties. On the other hand, the surface of the polyester film used in the conventional analog audio tape has a high roughness, and there is no analog audio tape that can satisfy the above properties and can be actually used. Furthermore, more and more audio cassettes are used outdoors in summer or on cars, so they are often used in harsh temperature environments. In this case, the tape must have excellent heat resistance, and it will not change its properties even in a more severe environment. It is necessary to develop a tape that does not change its properties even at high temperatures of up to 90 to 10 (TC. Therefore, it is necessary to develop The base film that causes the above problems is used as the base of the digital audio tape in the method of fixing the magnetic head, in other words, the base film has excellent recoverability for elongation, excellent flatness and lubricity, and the property at high temperature does not change. Provide magnets for digital recorder cartridges ......... ΓΓ ........................ ..................................... Pretend ...... ................ Order ..................... line (please read the precautions on the back before filling the nest (This page) This paper uses the Chinese Hexascale (CNS) A4 specifications (210x297 mm) A6 B6 321665 V. Description of the invention (3) Biaxially oriented polyester base film with tape. Another object of the present invention is Provides a biaxially oriented polyester base film for magnetic tape. When used as a magnetic tape of a digital recorder with a fixed magnetic head method, its recovery is excellent, and the inclined wall of the magnetic head guide extends one side of the tape , And then restore the original state, showing less recording distortion and less out-of-round changes, and excellent running properties and audio (electromagnetic) characteristics. Another object of the present invention is to provide a biaxially oriented polyester base film, giving the tape the above properties and excellent Lubricity. Another object of the present invention is to provide a magnetic tape for a digital recorder cassette, the base film of which is formed by the above-mentioned biaxially oriented polycool base film of the present invention and has the above-mentioned properties. From the following, other objects and advantages of the present invention will be known. According to the present invention, the biaxially oriented polyester base film used in the cassettes of digital recorders firstly contributes to the objectives and advantages of the present invention. The features are: (a) When the biaxially oriented polyester base film stretches in the longitudinal direction At 5%, the stress is at least 12kg / ·· 2, (b) The residual elongation in the longitudinal direction is 0.2% or less, and the residual elongation in the transverse direction is 0.3% or less. (C) No heat treatment at 1 0 5 " C After 30 minutes, the thermal shrinkage in the longitudinal direction is 1.5% or less, (d) at least one surface of the biaxially oriented polyester base film has a surface roughness Ra of 25η η or less, (e) the film thickness is from 3 to The scope of 12 # ·. This paper scale is applicable China National Standard (CNS) Grade A 4 (210x297 mm) .................................................. ........... (Please read the precautions on the back before filling the nest page) Printed by the Employees and Consumers Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs A6 B6 Printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy Description of the invention (4) The above five storage requirements (a) to (e) define the biaxially oriented polyester base film of the present invention. When stretched by 5% in the longitudinal direction, the biaxially oriented polyester base film of the present invention must have a stress of at least 12 kg /. »2. It is best to adjust the stress at 5% elongation between the recording and playback of the tape. When the recording and playback time is 60 minutes or less, the above force is preferably 12 to 15 kg / β · »When the recording and playback time exceeds 60 minutes but not more than 90 minutes, the above stress is preferably 15 to 20 kg / ··2. When the recording playback time exceeds 90 minutes but does not exceed 150 minutes, the above stress is preferably 20kg / «· 2 or more. Due to this requirement, it can prevent the expansion / contraction and permanent deformation of the tape edited at the start, stop time or in Xiaozi, and the tape can be recovered from the deformation immediately. Furthermore, it can prevent the tape fixed pin of the guide tape width from causing the tape side Continuous permanent deformation β When the elongation force at which the 5% extension is less than 12kg / ·! # 2, the tape is subject to elongation and deformation due to the elongation while the belt is running or the tension change at the start / stop time. As a result, the output changes greatly or the sound quality deteriorates. Furthermore, one side of the tape is permanently elongated and deformed by tilting the fixing pin, and the magnetic head contact becomes poor. As a result, the electromagnetic reactivity is deteriorated. Theoretically, the conventional film forming method can produce the biaxially oriented polyester base film of the present invention. For example, it can be produced by the following methods: the dry polymer is melted and extruded, and the extrudate is cooled on the prayer drum to prepare an unstretched film. The unstretched film is simultaneously or biaxially stretched and heat-set by a shovel. In order to achieve a stress of at least 12kg / ·· 2 when extending 5% in the longitudinal direction, {please read the precautions on the back before filling the nest page} This paper size is used in China National Standard (CNS) Grade 4 (210X297 Cli) A6 B6 printed by the employee consumer cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs 5. Description of the invention (5) The unstretched film can be stretched horizontally and longitudinally with a general stretching stick or tenter, or it can be stretched in the middle Longitudinal and elongated. Furthermore, the unstretched film can be biaxially stretched simultaneously or successively in multiple steps in various directions. Specifically, it can be elongated by known methods. When the membrane material is a polyester composed of ethylene terephthalate as the main repeating unit, the elongation temperature is usually between 80 and 140 ° C, and the elongation ratio in the longitudinal direction is 3.0 to 5.0 (preferably 3.3 to 4.3). The transverse stretch ratio of 3.0 to 5.0 (preferably 3.5 to 5.0) β the resulting biaxially oriented film is thermally coagulated at a temperature between 150 and 260 ° C (preferably 180 and 250 ° C) for 1 to 100 seconds. When the membrane material is a polyester composed of 2,6-pentanedicarboxylate as the main repeating unit, the elongation temperature is usually between (Tg-ΙΟ) and (Tg + 70) ° C (Tg = polyester Glass transition temperature}, the longitudinal elongation ratio is 5.0 to 10.0, and the transverse elongation ratio is 3.0 to 8.0. The temperature of the resulting biaxially oriented film at (Tg + 70) and (for example, between 180 and 250 ° C (Temperature) Thermosetting for 1 to 100 seconds. In the biaxially oriented polyester base film of the present invention, the residual elongation in the longitudinal direction and the residual elongation in the transverse direction must be 0.2% or less and 0.356 or less, respectively (requirement (b)). The residual elongation in the longitudinal direction is preferably 0.15% or less, preferably 0.1% or less, preferably 0.05% or less. The residual elongation in the trace direction is preferably 0.25% or less, more preferably 0.2% or less, 0.15% or less Optimal. Due to this requirement, when the tape rotates on the inclined wall of the head guide, even if the tape is forced to stretch green on one side, the tape shows excellent recovery after passing through the head, specifically, when the residual extension in the lateral direction The size of this paper is larger than that of the longitudinal direction. The Chinese National Standard (CNS) Grade 4 (210X297mm) is used ........................... .................................................. .............. 装 ...................................................... .......... 线 _ {Please read the precautions on the back before filling the nest page) A6 B6 321665 V. Description of the invention (6) {Please read the precautions on the back before filling the nest page} At this time, the tape shows exceptionally good recoverability, no residual elongation or permanent deformation, the tape is connected to the head (head contact), and the output characteristics and sound quality of the tape are good. When the residual elongation in the longitudinal direction is greater than 0.2% and / or the residual elongation in the lateral direction is greater than 0.3%, the edge of the tape is elongated or folded when the tape rotates on the inclined wall of the head guide, and the tape contacts the head ( Head contact) is bad. As a result, the recording signal during recording is leaked, or the output during playback is insufficient. The residual elongation varies depending on the heat setting temperature. Therefore, it is best to hold the residual elongation in the longitudinal direction, the residual elongation in the transverse direction, the stress at 5% elongation in the longitudinal direction, and change the heat setting temperature within the appropriate heat setting temperature range, and compare the measured data to determine the best heat setting temperature. In the biaxially oriented polyester base film of the present invention, when the film is heat-treated at 105 ° C under load for 30 minutes, the thermal shrinkage in the longitudinal direction must be 1.5% or less (requirement (c)). The above heat shrinkage is preferably 1.2% or less, preferably 1.0% or less. When the heat shrinkage percentage is too large, the magnetic tape suffers large deformation in the high temperature environment such as summer, and the properties of the magnetic tape are impaired. Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs. Appropriate selection of heat treatment conditions within the upper heat setting treatment conditions can achieve the above heat shrinkage under conditions of 105 ° C and 30 minutes. Furthermore, it can also be achieved by passing the upper heat-set film through two rollers with different rotation speeds and subjecting the film to relaxation treatment at a temperature equal to or higher than the glass transition temperature (Tg) of polyester. However, the method of thermal shrinkage is not limited to the above method. In the biaxially oriented polyester base film of the present invention, the surface roughness Ra is in the range of 5 to 25na, preferably 8 to 20iib (required (d)) e due to this. -8-This paper size is used China BB Home Prototype (CNS) Grade A (210X297 mm) A6 B6 printed by the Staff Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy V. Invention Instructions (7) If requested, the cassette of the digital recorder can be obtained without the lubricity. Layer, but has surface properties equivalent to standard VTR tapes, as described in " DCC · MD Guide Book: above. The nature of this tape is also good. When the surface roughness Ra is greater than 25η ·, the rough surface of the base film affects the magnetic layer and makes it rough, just like the cassette of a traditional digital recorder. Therefore, the electromagnetic characteristics required for high-density recording tapes are reduced and leakage occurs. When Ra is less than 5na, the friction number of the bottom film is too large, it is difficult to handle the film and roll into a stick shape. Furthermore, when no lubricity is given to the reverse coating, the lotus rotation properties of the digital recorder cassette are poor. Finally, in the biaxially oriented polyester base film of the present invention, the thickness needs to be 12; ub or below (required (e)) «According to the recording and playback time to determine the preferred film thickness» when the recording and playback time is 60 At minutes or less, the film thickness is preferably 9 to 12 #. When the recording and playback time exceeds 60 minutes but does not exceed 90 minutes, the film thickness is preferably 6 to 3 # ·. When the recording and playback time exceeds 9G minutes but does not exceed 150 minutes, the film thickness is preferably 4 to 6; u ·. When the film thickness is greater than 12 #, the film cannot achieve the functions required by the cassette of the compact digital recorder. The lower limit of the film thickness is not subject to other restrictions. However, when the film thickness is less than 4 // ·, even if the stress at 5% elongation in the longitudinal direction is at least 12 kg / n · 2, the rigidity of the tape is insufficient. As a result, the magnetic tape exhibits unstable lotus turn properties and is susceptible to troubles such as elongation, folding, and knotting. Furthermore, when the thickness is reduced, the residual elongation is greatly reduced. Β Specifically, when the film thickness is 3α Β or less It is difficult to maintain a residual elongation of 0.2 or less. The magnetic tape is extended along an edge by the inclined wall guided by the magnetic tape. Because this paper size is suitable for China National Standards (CNS) Grade 4 (210X297 mm) ... .................................................. ............................... Pretend ................. ..... order ..................... line (please read the precautions on the back before filling the nest page) A6 B6 321665 5. Description of the invention ( 8) (Please read the precautions on the back first and then the Ewo page). Therefore, the lower limit of the film thickness is preferably 4 // · or greater. For the biaxially oriented polyester base film of the present invention, it is best to select the stress at 5% elongation and residual elongation according to the recording and playback time, ~ the film thickness is as follows, so the size and weight can be reduced, and the The edge of the lotus turn time and start and stop time are damaged, elongated and deformed. When the recording and playback time is 60 minutes or less, the stress in the 5% elongation time in the longitudinal direction is 12 to 15 kg / B · 2, and the residual elongation in the longitudinal direction is preferably 0.15% or less, preferably 0.10% or less, 0.05% or less is optimal, and the film thickness is 9 to 12 #. Furthermore, the residual elongation in the transverse direction is preferably 0.2% or less, more preferably 0.15% or less, and most preferably 0.1% or less. When the recording and playback time exceeds 60 minutes but does not exceed 90 minutes, the stress at 5% elongation in the longitudinal direction is 15 to 20 kg / iB2, and the residual elongation in the longitudinal direction is preferably 0.15% or less, fl. 10% or less Even better, 0.05% or less is optimal, and the film thickness is 6 to 9 // «1. Furthermore, the residual elongation in the transverse direction is preferably 0.3% or less, more preferably 0.2% or less, and most preferably 0.15% or less. When the recording and playback time exceeds 90 minutes, the stress in the 5% elongation time of the longitudinal direction is at least 20kg / zu · 2, and the residual elongation in the longitudinal direction is preferably 0.15% or less, preferably 0.10% or //, 0.05% or less is best, printed by the employee consumer cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs% 3 ο is good 0 the best length is the most stretched out or the residual% J 5 to 1 horizontal 0. 9 > good 5J si ISPS 〇 下 ηto or d.2% 4 ο, the thickness of the thickness is mainly based on the film or the good double-shaped version of the original material

Diacetate phthalocyanine is composed of mono-esters, ethyl esters, polymethyl esters, dimembrane 6-esters, 2 ′ poly-orientated uniaxial esters. The paper size is applicable to China National Standards (CNS) A4 specifications (210X297 mm) A6 B6 printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs 5. Description of the invention (9) Composition of diester units ^ The main repeating unit is a polyester of ethylene terephthalate. Examples include not only homopolymerization of polyethylene terephthalate The substance r also contains a polyethylene terephthalate copolymer (wherein at least 8% of the acid component is formed from terephthalic acid and at least 90% of the glycol component is formed from ethylene glycol) and contains at least 85% (Preferably at least 90% by weight) a polymer blend of polyethylene terephthalate and other polymers of 15% by weight or less (preferably 10% by weight or less). Examples of copolymer-forming acids include aromatic dicarboxylic acids (such as dicarboxylic acid, isophthalic acid, diphenyl carboxylic acid, benzophenone dicarboxylic acid), aliphatic dicarboxylic acids (such as succinic acid, Adipic acid, sebacic acid, dodecane dicarboxylic acid), alicyclic dicarboxylic acid (such as hexahydroterephthalic acid and 1,3-goldoprene dicarboxylic acid) β copolymers to form diol examples include 1, 3-Propanediol, 1,4-butanediol, 1,6-hexanediol, octanediol, 1,4-cyclohexanedimethanol, terephthalic acid. Examples of "other polymers" included in the polymer blend include polyamide, polyolefin, and various polyesters. Examples of the polyester whose main repeating unit is 2,6-naphthalene dicarboxylic acid ester include not only a homopolymer of 2,6-ethylene naphthalate but also a copolymer of polyethylene 2,6-naphthalene dicarboxylate Substances (wherein at least 80βο1% of the acid component is formed from 2, 6- # dicarboxylic acid and at least 9 0 Β ο 1% of the diol component is formed from ethylene glycol) and contains at least 85% by weight (preferably at least 90% by weight ) A polymer blend of polyethylene 2,6-dicarboxylate and other polymers of 15% by weight or less (preferably 10% by weight or less). Examples of copolymer-forming acids include aromatic dicarboxylic acids (such as terephthalic acid, -1 1-this paper standard _ using Chinese National Standards (CNS) A4 specifications (210X297 mm) ... .................................................. ......................................................... .Can .................... Line (please read the precautions on the back before filling the nest page) A6 B6 printed by the Employees Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs , Description of the invention (10), isophthalic acid, 2,7-dicarboxylic acid, diphenylamine dicarboxylic acid, benzophenone dicarboxylic acid), aliphatic dicarboxylic acids (such as succinic acid, adipic acid , Sebacic acid, dodecane dicarboxylic acid), alicyclic dicarboxylic acid (such as hexahydropeptidic acid and 1,3-gold alkane dicarboxylic acid copolymer to form a diol. Examples include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, octanediol, 1,4-cyclohexanedimethanol, terephthalene dimethanol. &Quot; Other polymers " included in the polymer blend Examples include polyamide, polyolefin, and various polyesters. The above-mentioned polyesters as raw materials may include lubricants, smoothing agents, dyes, stabilizers, Gas. The upper glycan as the raw material is usually produced according to the known method of the melt polymerization method. During production, additives such as catalysts can be added. To adjust the surface roughness of the biaxially oriented polyester base film of the present invention Ra, inert fine particles may be added as a raw material of polyester. Examples of the above-mentioned inert fine particles include (1) di-vaporized silicon; (2> vaporized aluminum; (3) vaporized products of Mg, Zn, Zr ·, Ti; (4) Ca and Ba sulfate; (5) Li, Na, Ca phosphate (including monohydrate and dihydrate); (6) Li, Na, K phosphate; (7) Ca, Ba , Zn, Hn terephthalate; (8) Mg, Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, Co, Hi titanate; (9) Ba and Pb chromate; (10) Sulphur (such as carbon black and graphite); (11) Glass (such as powdered glass and glass beads); (12) silicates of Ca and Mg. Silicic anhydride, hydrated silicic acid, gasification are preferred Aluminum, aluminum silicate (including burnt materials and hydrates), lithium monophosphate, trilithium discoate, sodium discoate, calcium phosphate, europium phosphate, titanium vapor, lithium benzoate, calcium sulfonate. Re-1 2 -This paper The scale is based on China National Standard (CNS) Grade 4 (210X297mm) .................................... ..............._ {Please read the precautions on the back before filling the nest page} A6 B6 printed by the Staff Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy V. Description of the invention (11) It is possible to use fine particles of thermally conductive polymer, such as silicone resin or polyacrylic acid. The above-mentioned inert fine particles may be used alone or in combination. The above-mentioned surface roughness can be achieved by appropriately determining and adjusting the particle size and amount. During or after the polymerization of the polyester, the above-mentioned inert fine particles may be added to the polyester. For example, the method of adding inert fine particles to the polyester during or before the polymerization of the polyester, the method of kneading the inert fine particles with the polyester when the polymerized polyester is pressed, or when the polyester is melted and extruded into a sheet form A method of kneading inert fine particles. In addition to the above method, a method in which phosphorus fractions or other desired components are added and allowed to precipitate during polymerization, or a method in which the polymer is blended with the polymer obtained by any of the above methods may be used. The biaxially oriented polyester base film of the present invention may have a lubricious anti-face coating β on the opposite surface where the magnetic layer is formed. In this case, it is preferable to form the opposite surface of the film of the reverse surface (surface where the magnetic layer is formed) The Ra reverse coating layer having 8ηB or less can be formed by any known method, such as the method shown in Japanese Patent Publication Nos. 200427/1983 and 248323/1991. More specifically, it is better to apply the coating liquid of the dispersed fine powder additives of the adhesive to the polyester film, or the coating liquid of the polymer (forming a lubricating non-contiguous coating) on the polyester film, to Form a reverse coating. The film to be coated with the coating liquid may be an unstretched film, a uniaxially stretched film, or a biaxially stretched film. After the coating liquid is applied, the unstretched film and the uniaxially stretched film should be stretched to obtain a biaxially stretched film. Although not subject to other restrictions, the thickness of the reverse coating layer is preferably 2 # n or less, to avoid shadows such as reduced output caused by printing on the magnetic layer. Furthermore, the surface roughness Ra of the reverse coating is preferably 10 to 30 -1 3- This paper scale uses the Chinese National Standard (CNS) A 4 specifications (210X297 mm) '... .................................................. ......................................................... .ΤΓ ..................... line. (Please read the precautions on the back before constructing this page) A6 printed by the Staff Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs B6 5. Description of the invention (12) ηιη, 10 to 20 nm is better, to achieve the excellent lotus transfer properties of the magnetic tape, and to avoid the fine uneven surface of the reverse coating printed on the magnetic layer, such as output reduction Shadow honey. When the polyester used as the raw material is polyethylene 2,6-naphthalene dicarboxylate, the biaxially oriented polyester base film of the present invention can exhibit large stress, small shrinkage, and small thickness at 5% elongation. That is, according to the present invention, it is preferable to provide a biaxially oriented polyethylene 2,6-dicarboxylate base film for a magnetic tape of a digital recorder cassette, and it is particularly advantageous in (a ') when the biaxially oriented polyester base When the film has an elongation of 5% in the longitudinal direction, the stress is at least 23 kg / BBT2 (b) The residual elongation in the longitudinal direction is 0.2% or less, and the residual elongation in the transverse direction is 0.3% or less. (c ') After no-load heat treatment at 105 ° C for 30 minutes, the longitudinal heat storage is 1.5% or less, (d) At least one surface of the biaxially oriented polyester base film has a surface roughness Ra of 25η or less , (e ') The film thickness is in the range of 3 to 6. At 5% elongation, the longitudinal stress is at least 23kg / * b2, preferably at least 25ltg / «i · 2 (required (a ')). Furthermore, at 5% elongation, the transverse stress is preferably at least I2kg / BD12, at least 15kg / BB2 is better. The residual elongation in the longitudinal direction and the horizontal direction must be 0.2% or less and 0.3% or less (required (b) h The residual elongation in the longitudinal direction is preferably 0.15% or less, preferably 0.1% or less , 0.05% or less is the best. Landscape -14- This paper scale adopts China Sleepy Family Standard (CNS) A 4 specifications (210x297 mm) .................. .................................................. ................ Pretend ...................................................... ............. Line (please read the precautions on the back before filling the nest) 321665 A6 B6 Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs V. Remnants of the description of invention (13) The elongation is preferably 0.2% or less, preferably 0.15% or less, and most preferably 0.1% or less. The longitudinal heat shrinkage (105 ° C, 30 minutes, no load) is 0.5% or less, preferably 0.3 % Or below, 0.2% or below is better. The surface roughness of at least one surface of the membrane is 25η * or below, the most In the range of 5 to 25πβ (requirement (d)). In addition, the film thickness is in the range of 3 to 6; / ·. The preferred biaxial orientation formed by the raw material of polyethylene 2,6-naphthalene dicarboxylate The base film can also have the above-mentioned reactive coating. The inventors' research also found that a film having exactly the same properties as the aforementioned biaxially oriented polyester base film can also be used as a laminated film. That is, it is used in a digital recorder cassette The special features of the biaxially oriented laminated polyester base film of magnetic tape are: (a) When the bi-oriented oriented polyester base film is elongated by 5% in the longitudinal direction, the stress is at least 12kg / · »2, (b) the residual in the longitudinal direction The elongation is 0.2% or less, the residual elongation in the transverse direction is 0.3% or less, (c) After 30 minutes of no-load heat treatment at 105 eC, the thermal shrinkage in the longitudinal direction is 1.5% or less, (e) has 8η · The first polyester layer of Ra or below and the second polyester layer with Ra in the range of 8 to 40 η · are the outermost layers, (e) The thickness of the IIH film is in the range of 3 to 12 // ·. According to the present invention Prior to solving the corresponding requirements of biaxially oriented polyester base film -1 5-(Please read the precautions on the back before filling the nest page). Binding • Binding. Weft. This paper ruler Bu using Chinese National Standard (CNS) A 4 size (210X297 mm) B6 five described (14) invention, can be appreciated on Alex requirements (a), (b), (c), (e). The requirements (d) of the biaxially oriented lamination poly-base film of the present invention are that: the first poly layer having lia of 8η · or less and the second polyester layer having Ra in the range of 8 to 40η · are the most Outer layer. The raw materials of the first polyester layer and the raw materials of the second polyester layer may be the same or different, and these two materials are preferably selected from the same polymer. The biaxially oriented laminated polyester base film may have a laminated structure in which at least one third polyester layer is present between the first and second polyester layers. The raw material of the third polyester layer may be the same as or different from that of the first and second polyester layers, and the raw material of the third polyester layer may be selected from the same polymers as the first and second polyester layers. In particular, the first to third polyester layers are preferably formed of the same polymer as the raw material. Theoretically known film forming methods can produce the biaxially oriented laminated polyester base film of the present invention. For example, it can be produced by the following method: the dried polyester forming the upper layer is melted and co-extruded via a die, the extrudate is cooled on the drum to prepare an unstretched film, and the unstretched film is simultaneously or spliced Biaxially elongated and thermoset. Furthermore, for example, the above-mentioned co-extrusion method can be replaced by the extrusion lamination method. The first polyester layer having an Ra of 8 nm or less generally provides the surface on which the magnetic layer is to be formed. Ra of the first polyester layer is in the range of 1 to 8 ?, preferably 3 to 7 ?. Printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs (please read the precautions on the back before filling the nest page) Ra of the second polyester layer is in the range of 8 to 4ϋη ·, preferably in the range of 10 to 40η ·, The range of 15 to 40η «ι is better. In addition, regarding the ratio of the first polyester layer to the second polyester layer, the second polyester-1 6-This paper scale is applicable to the Chinese Standard (CNS) A4 specification (210X297 mm) A6 B6 Central Standard of the Ministry of Economic Affairs Printed by the Bureau ’s Consumer Cooperatives 5. Description of invention (15) The layer thickness is preferably 5 to 50% of the entire thickness of the laminated polyester layer. When the thickness of the second polyester layer is too small, the number of inert particles contained in the layer is small, so the number of protrusions on the surface of the layer is small, and the number of small protrusions on the surface is small. As a result, the surface roughness is extremely low, and the tape running property is poor . Furthermore, the coarse particles protrude from the surface and wear out the surface of the film, causing the other hand. When the thickness of the second polyester layer is too large, the coarse particles in the second polyester layer protrude from the surface of the first polyester layer. Therefore, the surface of the first polyester layer is roughened. As a result, the gap between the magnetic head and the magnetic tape is increased, and the electromagnetic standby is formed, which is not conducive to achieving high-density recording and high sensitivity. Furthermore, when the thickness of the second polyester layer is too large, the particle amount of the laminated film is large, and the production Increased costs are not economical. It should be understood that the aforementioned preferred embodiments regarding the recording and playback time also exist in the biaxially oriented polyester laminated base film of the present invention. Also, when the recording and playback time is 60 minutes or less, the stress at 5% elongation in the longitudinal direction is 12 to 15 kg / ·· 2, the residual elongation in the longitudinal direction is 0.15% or less, «Η film thickness is 9 To 12 # ·. When the recording and playback time exceeds 60 minutes but does not exceed 90 minutes, the stress at 5% elongation in the longitudinal direction is 15 to 20 kg / · !! 2, and the desired residual elongation is 0.15% or less, the thickness of the beta film 6 to 9 When the recording and playback time exceeds 90 minutes, the stress at 5% elongation in the longitudinal direction is at least 2flkg / * · 2, the residual elongation in the longitudinal direction is 0.15% or less, and the thickness of the laminated film is 4 to 6 copies The β-sheet polyester base film of the invention as the raw material of the polyester is preferably used as the main repeating unit of p-peptide ethylene glycol or ethylene glycol 2,6-carboxylate-1-7-loaded ... ................... Order ............... line {Please read the notes on the back first (Zaiqiwo this page) This paper standard applies to the national standard (CNS) A4 specifications (210X297 mm) printed by the Ministry of Economic Affairs Central Standards Bureau staff consumer cooperatives A6 B6 V. Invention description (16) made of polyester. This polyester as a raw material has already been explained. Furthermore, when the polyester used as the raw material is polyethylene 2,6-folate dicarboxylate, the above-mentioned laminated polyester base film of the present invention can exhibit a large stress, a small heat shrinkage percentage, and a small thickness. That is, according to the present invention, it is preferable to provide a biaxially oriented laminated poly 2,6-ethylene dicarboxylate base film for a magnetic tape of a digital recorder cassette. It is to be noted that (a ') when biaxially oriented When the laminated base film has a longitudinal elongation of 5%, the stress is at least 23 kg / me2. (B) The residual elongation in the longitudinal direction is 0.2% or less, and the residual elongation in the transverse direction is 0.3% or less, (c ') at 105 ° C After 30 minutes of no-load heat treatment, the thermal shrinkage in the longitudinal direction is 0.5% or less, (d ') a first polyester layer having an Ra of 8η · or less and a second polymer having an Ra of 8 to 40η · The ester layer is the outermost layer, the polyester of the first and second polyester layers are both polyethylene 2,6-naphthalene dicarboxylate, and (e1) the thickness of the laminated film is in the range of 3 to 6 ab. According to the solution of the corresponding requirements of the aforementioned biaxially oriented polyester base film of the present invention, it can be understood that the above requirements (a '), (b), (cl, (e') e The above requirement (d ') lies in: the first polyester The layer and the second polyester layer are formed of polyethylene 2,6-naphthalate as raw materials. It should be understood that the explanation of the requirement (d) of the biaxially oriented laminated polyester base film of the present invention can also be applied to this It is omitted, such as Ra and the ratio of the first and second polyester layers. -18- This paper size is installed in the Chinese National Chess Standard (CNS) Grade 4 (210X297mm) ...... ............... 玎 ..................... line (please read the precautions on the back before Evoben Page} A6 B6 321665 V. Description of the invention () The biaxially oriented polyester base film of the present invention (including satin film) uses the magnetic tape for a digital recorder cassette (the magnetic tape of the present invention is formed on a surface on a magnetic layer Lubricity can be imparted on the surface where the magnetic layer does not exist, giving the reverse coating II. Furthermore, it is best to form the magnetic layer on the above biaxially oriented poly 26_ 桊 monocarboxylic acid ethylene difig bottom mold (including the lamella film) to produce The following tape refers to the example The present invention is explained step by step. The various property values and persistence support and / or definitions used in the present invention are as follows: (1) The force film at 5% elongation is cut into a sample with a width of 10 ·· and a length of 15〇BB, the sample Stretched with an instr〇n type universal tensile tester at a distance between 100 ° and between chucks, a stretching rate of 10Be / llinute, a rate of 100n / iinute plaque. The resulting load_5% of the elongation curve The brewing power at the time of elongation is converted into a value per block area (B · 2). (2) The residual elongation is 3/20 hours wide and 600η · long film samples are placed in Santoyo Precision Universal PJ3 21F In the measuring bed, one end of the longitudinal fixed β-spot sample meets the free roller parallel to the sample bed (the top of which is the same height as the sample bed), allowing the membrane sample to fall vertically. The box measures the purlin points of the membrane sample on the sample bed The distance between 2 and 0 ". Then, a load of 200 g is applied to the hanging end of the membrane sample. After allowing the sample membrane to stay in this state for 10 minutes, the 200 g load is removed and the sample membrane is allowed to remain for 10 minutes. Then, The sample film can be changed in size. The residual elongation is determined by the following formula, .................................... .. .......................................... Pretend. ..................... order ............... line {Please read the back of the first Matters needing attention and then fill this page. J Printed by the Ministry of Economic Affairs, the Central Bureau of Economic Development, Beigong Consumer Cooperative

△ S Residual elongation X 100 -19- This paper scale is applicable to China National Standards (CNS) A 4 specifications (210X297 mm) A6 B6 printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy V. Description of invention (18) where S〇 Is the length under no load, AS is the amount of dimensional change caused by 200 g load. (3 > Membrane surface roughness < Ra > — Needle contact type surface roughness tester (Surfc 〇der SE 3 0 C of K 〇saka Laboratories) at a needle pressure of 30 W at 2 > ub needle Use the radius to prepare the plaque table (film surface roughness curve). From the film surface roughness curve, find the part with the measured length L in the centerline direction. The centerline of this part is taken as the X-axis length multiplication direction as the Y-axis The degree curve is expressed as Y = f (X). The following formula Ra (yU b) is defined as the film surface roughness.

1 rL

Ra = — If (x) Idx (4) heat shrinkage ^ ^ A film about 30cn long and lcn wide (precisely measure the length in advance) is placed in the furnace at 70 ° C without load and heat treated for 30 minutes. Then, the film was moved out until it reached room temperature, and the length of the film was measured to judge the dimensional change. Formally decided to heat shrink,

△ L heat shrinkage = -X 10〇L 〇 Where L〇 is the length before heat treatment, AL is the amount of dimensional change. (5) The durability of the lotus turn of the magnetic tape The coating composition containing 70% by weight of 7-Fe203 and 3Q by weight of the adhesive is applied to the adhesive. The adhesive contains 5% by weight of urethane rubber, -2 0-This paper scale uses the Chinese National Standard (CNS) A 4 specifications (210X297 mm) ..................... .................................................. ................... installed .......................... may ... ............... green (please read the precautions on the back before filling the nest page) A6 B6 printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy V. Description of the invention (19) 3.5 Nitrogen nitrate weight of 1.5%, vinyl acetone of 1.5% by weight, methyl ethyl ketone of 90% by weight, isomeric ester compound as curing agent of 15% by weight * »As a result, a roll of 6 0 0 β coated with magnetic layer was obtained. Wide film, cut with a slitter into a 3/20 hour wide tape. When starting and stopping the tape operation at the Panasonic Digital Recorder RS-DC10 and repeating the tape for 100 hours, evaluate the durability of tape rotation as follows. ≪ According to three Estimate of bow rating> Α: The belt edge is not elongated and folded. Furthermore, no abrasion dust or white dust adheres. Β: The belt edge is slightly wrinkled or folded due to the elongated edge, and a small amount of white dust is attached to the crock. C: The band edge is greatly elongated and folded. A large amount of white ash is produced by abrasion. (6) The percentage of non-defective products is taken out in a roll shape of 5 0 0 · β wide and 4 0 0 0 β · long. When 100 rolls are prepared in this way, the number of non-defective rolls is expressed It is a percentage. &Quot; Defect-free product ”refers to a roll of film taken out in a cylindrical shape, which does not form squares or slack, nor wrinkles. Example 1 Contains 0.2% by weight of calcium master particles (average. Particle size is 0. 8 # B) Polyethylene terephthalate with an inherent viscosity of 0.65dl / g (measured in o-nitrophenol at 25 ° C) is dried at 160 * C, melt-extruded at 28fl ° C, and at a temperature of 40 ° C The casting drum is rapidly cooled / solidified to produce an unstretched film with a thickness of about 150 # B. -2 1-This paper scale is equipped with the Chinese National Standard B (CNS) Grade 4 specification (210X297 mm) ... .................... Stare ..................... line. (Please read the back side first (Notes and refill this page) A6 B6 printed by Beigong Consumer Cooperative of Central Bureau of Standards of the Ministry of Economic Affairs 5. Description of the invention (20) The unstretched film is at a temperature of 90 ° C between two sticks with different speeds 3.8 times longer in the longitudinal direction, then stretcher at 9 (TC in the horizontal direction ~ 3.8 Times, then heat-treated at 200 eC for 30 seconds, cooled at 90 ° C for 15 seconds, taken out to obtain a 10 # m thick biaxially oriented polyethylene terephthalate film. Then, the magnetic coating composition (the composition is described in The above (5) " Lane turn durability of magnetic tape " is coated on a biaxially oriented polyethylene terephthalate film to obtain a magnetic tape. Table 1 shows the properties of the resulting film and tape. Table 1 clearly shows that the base film has excellent handling properties and the tape has good lotion durability. Example 2 An unstretched film was obtained in the same manner as in Example 1. The resulting unstretched film was stretched 4.5 times in the longitudinal direction between two sticks with different descriptions at a temperature of 60 ° C, and then at 60 ° C was stretched 3.5 times in the transverse direction, and then treated in the same manner as in Example 1, to obtain a 10 # · thick biaxially oriented polyethylene terephthalate film and magnetic tape. Table 1 shows the results, as good as Example 1. Example 3 A biaxially oriented polyethylene terephthalate film and magnetic tape were obtained in the same manner as in Example 1, except that the inert solid particles used in Example 1 were 0.2% by weight of monodispersed silica particles having an average particle diameter of 0.4 # β To replace. Table 1 shows the results, as good as Example 1. Comparative Example 1 In the same manner as in Example 1, an unstretched film was obtained. The resulting unstretched film uses the Chinese National Standard (CNS) Grade 4 specifications (210X297 mm) at -2 2-the size of this paper ......................... .... 玎 ...................... ^ (Please read the back side first. Note before filling the nest page) _B6_ V. Invention description (21 ) 90 ° C temperature is elongated 3.5 times in the longitudinal direction between two sticks with different rotation speeds, then stretched 3.5 times in the transverse direction with a tenter at 90 ° C, heat-treated at 170 ° C for 30 seconds, and then in Example 1 Treated in the same manner as above, and obtained 1〇 # «1 thick biaxially oriented polyethylene terephthalate film and tape» Table 1 shows the results, because the bottom film has a low stress and high residual elongation at 5% elongation in the longitudinal direction, Therefore, the tape is subject to folds and folds when it turns. Furthermore, since the base film exhibits high heat shrinkage, the magnetic tape undergoes large deformation when it is used and stored in a high-temperature environment like summer. Therefore, the magnetic tape is not suitable as a digital audio tape. Comparative Example 2 In the same manner as in Example 1, an unstretched film was obtained. The resulting unstretched film was stretched 3.0 times in the longitudinal direction at 90 eC between two sticks with different rotation speeds, and then stretched by a tenter at 9 (TC in the transverse direction by 4.5 times, at 20 (TC After heat treatment for 30 seconds, and then treated in the same manner as in Example 1, a 10AB thick biaxially oriented polyethylene terephthalate film and magnetic tape were obtained. Table 1 shows the results, the residual elongation of the base film is in the appropriate range, and 5 in the longitudinal direction % The force when stretched is low. Therefore, the tape is stretched, creased, and folded, and is not suitable for digital audio tapes. Comparative Example 3 Printed by the Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs (please read the precautions on the back before filling the nest (This page) The same unstretched film as in Comparative Example 1 was biaxially stretched in the same manner as in Comparative Example 1, and then heat-treated in a tenter at 241TC for 30 seconds. Thereafter, 10 # B was obtained in the same manner as in Example 1. Thick biaxially oriented polyethylene terephthalate and magnetic tape. -2 3 -This paper uses the National Standard (CNS) A4 specification (210x297 mm) 321665 A6 B6 V. Description of invention (22) Table 1 shows the results "Since the bottom film has a low stress and a high residual at 5% elongation in the longitudinal direction The length of the tape is wrinkled and folded when the tape is running, which is not suitable for digital audio tapes. Example 4 In the same manner as in Example 1, an approximately 130 // · thick unstretched film is obtained. The resulting unstretched film is at 60 ° C temperature is elongated 4.7 times in the longitudinal direction between two rods with different speeds, and then 3.5 times in the transverse direction with a tenter at 60 ° C, and then heat-treated in the same manner as in Example 1 to obtain a double 8-m thick Axis-oriented polyethylene terephthalate and a tape with a recording and playback time of 90 minutes. Table 1 shows the results. Example 1 is as good as in Example 1. Example 5 An unstretched film was obtained in the same manner as in Example 1. The resulting unstretched film The long film was stretched 2.0 times in the longitudinal direction between two sticks with different turns at a temperature of 70 ° C, and then 3.2 times in the transverse direction with a tenter at 90 ° C, and then heat-treated in litre by intermediate heat treatment. After that, the heat-treated film was heated with a heating rod at Ιϋ · 〇, and then the film tension between the heating rod and the cooling roll was adjusted to thermally shrink the longitudinal film to 0.5%. The resulting film was 6 # 1 thick. Then, Treat the membrane in the same manner as in Example 1 to obtain a tape with a recording and playback time of 120 minutes Table 1 shows the results, as good as in Example 1. Installed ...................... Ordered .............. ....... Wei (please read the precautions on the back before filling the nest page) Printed by the Beigong Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs -24- This paper scale uses the Chinese National Standard (CNS) A4 specifications (210X297mm) V. Description of invention (23) A6 B6 Printed by Employee Consumer Cooperative of Shenyang Standard Bureau of Ministry of Economic Affairs

Table 1 Unit Ex. 1 Ex. 2 Ex. 3 CEx. 1 Added particle type Calcium sulfonate Calcium sulfonate Monodisperse silica calcium masterbatch Particle size μ η 0.8 0.8 0.4 0.4 Amount wt X 0,2 0.2 0.2 0.2 Base film properties> Thickness u 10 10 10 10 Surface roughness (Ra) n Dirty 16 16 8 16 Stress at 5X elongation MD kg / ΙΒΗ 2 13.5 14.8 13.5 11.0 Residual elongation MD% 0.10 0.05 0.10 0.25 Residual elongation TD% 0. 10 0.14 0. 10 0.25 Thermal shrinkage (MD) 105ΪΧ 30nir% 0,8 1. 1 0.8 2.2 Percentage of non-defective products taken out% 98 98 90 98 Tape properties lotus turn persistence-AAAC

Ex. = Example, CEx. = Comparative example MD = Machine direction (= longitudinal) TD = Horizontal-to-be-mined--25- This paper scale adopts China National Standard (CNS) Grade 4 specifications (210X297mm) ... .................................................. .......................... Pretend ....................... T-line (please read the precautions on the back before filling the nest page) A6 B6 5. Description of the invention (24)

Table 1 (Continued) I Unit CEx · 2 CEx · 3 Ex. 4 Ex. 5 Type of added particles-calcium silicate calcium silicate calcium sulfonate calcium silicate calcium particle size Μ 0.8 0.8 0.8 0.8 amount wt% 0,2 0.2 0. 2 0,2 Base film properties Film thickness M Π1 10 10 8 6 Surface roughness (Ra) ηη 16 16 16 16 Stress at 5¾ elongation MD kg / ιοί 2 9.4 10.8 17.6 22.0 Residual elongation MD% 0.22 0.40 0. 04 0.05 Residual elongation MD% 0.04 0.42 0.14 0.18 Thermal shrinkage (MD) 10 5 ° CX 30iain% 0.8 0.5 1. 1 0.5 Percentage of non-defective products taken out% 98 98 98 98 Tape nature lotus turn durability-Β CAA (please read first Note on the back and fill in this page). Binding-binding: -Line. Printed by Beigong Consumer Cooperative of Central Bureau of Standards, Ministry of Economic Affairs

Ex. = Example, CEx. = Comparative example MD = Machine direction (= Portrait) TD = Landscape-26-This paper scale is applicable to China National Standard (CNS) A 4 specifications (210X297mm). Printed by the consumer cooperative A6 B6 V. Description of the invention (25) Example 6 Contains 0.2% by weight of vaporized titanium particles (average particle size is 0.2 # m) and has an intrinsic viscosity of 0.65dl / g (measured in o-phenol at 25eC) The poly (ethylene terephthalate) was dried at 160 ° C, melt-extruded at 280 ° C, and rapidly cooled / solidified on the yam drum at a temperature of 40 ° C, resulting in an unstretched film of about 1 60 thickness. The above-mentioned unstretched film was stretched 4.0 times in the longitudinal direction between two rams with different rotation speeds at a temperature of 80 ° C, then stretched 4.0 times in the transverse direction with a tenter at 80 ° C, and then at 2Q5 ° C Heat treatment for 10 seconds, cooling at 90 ° C for 15 seconds, and take out to obtain a 10 # B thick biaxially oriented polyethylene terephthalate film. Then, a coating liquid having the following components is applied to one surface of the film and dried to form a 1.2-B-thick reverse coating. The coating liquid composition of the reverse coating layer is 30 parts by weight of vinyl chloride-vinyl acetate copolymer. 15 parts by weight of acrylonitrile-butadiene rubber. 15 parts by weight of polyisocyanate. 25 parts by weight of calcium monohydrate with an average particle size of 0.8 // 200. 650 parts by weight of methyl ethyl ketone. Then, the magnetic coating component (the composition of which is described in (5) " Lianzhuan Durability of Magnetic Tape " On the surface of the diester film, a tape with a recording and playback time of 60 minutes was obtained. Table 2 shows the properties of the resulting film and tape. Table 2 clearly shows that the base film has excellent handling properties and the lotus transfer property of the magnetic tape is good. -27- This paper uses the Chinese National Standard (CNS) Grade 4 specifications (210X297mm) ^ ............................... .................. ^-{Please read the precautions on the back before filling the nest page) A6 B6 printed by the employee consumer cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs (26) Example 7 The unstretched film obtained in the same manner as in Example 6 was stretched 3.7 times in the longitudinal direction at a temperature of 70 ° C between binary rods with different paraphrases, and then a tenter It was stretched 4.3 times in the lateral direction at 70 ° C, and then treated in the same manner as in Example 6, to obtain a biaxially oriented polyethylene terephthalate film with a thickness of 10 ° B and tape β. Table 2 shows the results, as in Example 6— Good job. Comparative Example 4 In the same manner as in Example 6, an unstretched film was obtained. The resulting unstretched film was stretched 3.2 times in the longitudinal direction at 90 ° C between two boat rods with different speeds, then stretched 3.5 times in the transverse direction at 9D ° C with a tenter, and heat-treated at 17D-C for 30 Seconds, and then processed in the same manner as in Example 6, to obtain 10 # Teng thick biaxially oriented polyethylene terephthalate film and audio tape. Table 2 shows the results, because the bottom film has a low stress at 5% elongation in the longitudinal direction And high residual elongation. Therefore, the tape was turned and folded when the lotus was turned. Furthermore, since the base film exhibits high heat shrinkage, the tape is deformed when it is used and stored in a high-temperature environment like summer. Therefore, the magnetic tape is not suitable as a digital audio cassette. Comparative Example 5 In the same manner as in Example 6, an unstretched film was obtained. The resulting unstretched film was stretched 3.2 times in the longitudinal direction at 90 ° C between dipsticks with different speeds, then stretched 4.5 times in the transverse direction with a tenter at 90 ° C, and heat-treated at 230 ° C for 30 Seconds, and then processed in the same way as in Example 6, to get 10 // · thick-2 8-This paper size is installed in China Sleepy Standard (CNS) A 4 specifications (210X297 mm) ... ................ order ..................... line (please read the precautions on the back before filling in this Page) A6 B6 printed by the Employees ’Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs 5. Description of the invention (27) Biaxially oriented polyethylene terephthalate film and audio tape. Table 2 shows the results. Because the base film has low stress and extremely high residual elongation at 5% elongation in the longitudinal direction, the tape is elongated, folded, and folded β during lotus rotation. Therefore, the tape is not suitable for digital audio tapes. "Comparative Example 6 is the same as Example 6 The 10 # m thick biaxially oriented polyethylene terephthalate film and audio tape were obtained in this way, except that the titanium oxide particles were replaced by monodispersed silica particles with an average particle diameter of 0.01 # · 0.005% by weight. Table 2 shows the results . Due to the low surface roughness of the base film and its poor handling properties, the percentage of non-defective products taken out is poor. Furthermore, the magnetic layer surface of the magnetic tape shows poor lubricity and causes wear. The film is not suitable as a base film for digital audio tapes. 8 In the same manner as in Example 6, an unstretched film about 130 ^ 11 thick was obtained. The resulting unstretched film was stretched 4.8 times in the longitudinal direction at a temperature of 60 ° C between two sticks with different rotation speeds, and then stretched by a tenter at 6 (TC was stretched in the transverse direction by 3.7 times, and then In the same manner as in Example 6, heat treatment was performed to obtain a biaxially oriented polyethylene terephthalate with a thickness of 8 # B and a tape with a recording and playback time of 90 minutes. Table 2 shows the results, which is as good as Example 6. Comparative Example 7 In the same manner as in Example 8, an 8 // B thick biaxially oriented polyethylene terephthalate film and a tape with a recording and playback time of 90 minutes were obtained, except that the heat treatment temperature after biaxial elongation changed from 205 ° C to 160 "; 〇〇-29- This paper scale is applicable to the Chinese national standard (CNSI A 4 specifications (210X297 mm) ............................... Order ... ................... Line-(Please read the precautions on the back before filling the nest page) A6 B6 321665 V. Description of the invention (28) {Please read first- (Notes to be refilled on this page) Table 2 shows the results. The bottom film shows a high residual, the weight of the tape is wrinkled and folded when the tape is running. The film also has large heat shrinkage. Therefore, the film is not suitable for the bottom film of digital audio tape Comparative example 8 An unstretched film was obtained in the same manner as in Example 8. The resulting unstretched film was stretched 4.0 times in the longitudinal direction between two storage sticks with different paraphrases at a temperature of 70 ° C, and then at 70 ° C with a tenter Laterally elongated 3.5 times, heat-treated at 250 ° C for 30 seconds, and then treated in the same manner as in Example 1 to obtain 8> uB thick biaxially oriented polyethylene terephthalate film and recording and playback time of 90 minutes Audio tape. Table 2 shows the results. Because the backing film has high residual elongation, the tape is stretched during operation, wrinkling and folding occur. Therefore, the tape is not suitable as a digital audio tape. Example 9 In the same way as Example 9, undrawn The unstretched film obtained from the long film β was stretched 2.0 times in the longitudinal direction between two sticks with different paraphrases at a temperature of 75 ° C, and then stretched 3.4 times in the transverse direction with a tenter at 90 ° C, then It is heat-treated by intermediate heat treatment at 110 ° C. The film is further elongated by 3.6 times in the longitudinal direction at 10 ° C, and then heat-treated at 200 ° C. Then, the heat-treated film is heated with a heating stick at 100-C, and then the heating stick is finished The film tension with the cooling stick, the Ministry of Economic Affairs Central Standards Bureau employee consumer cooperative The thermal shrinkage of the longitudinal film was adjusted to 0.5%. The resulting film was 6 # thick. Then, the film was processed in the same direction as in Example 6. A tape with a recording and playback time of 120 minutes was obtained. -30-Paper size Use the sleepy national standard (CNS) A4 specification (210X297 mm) A6 B6 V. Description of the invention (29) Table 2 shows the result, which is as good as Example 6. Comparative Example 9 The undrawn method is obtained in the same way as Example 9. Long film. The resulting unstretched film is stretched 2.2 times in the longitudinal direction at 75 eC between the dipsticks with different paraphrases, then stretched 3.0 times in the transverse direction with a tensioner at 90 * C, and then heat treated in the middle Heat treatment at 110 ° C. This film was stretched 3.6 times in the longitudinal direction at 10 ° C and heat-treated at 240 eC to obtain a 6-thick film. The resulting film was treated in the same manner as in Example 8 to obtain a tape with a recording and playback time of 120 minutes. Table 2 The result is shown. Due to the extremely high residual elongation of the backing film, the tape is stretched during lotus rotation, causing folds and folds. Furthermore, it shows high heat shrinkage. Therefore, the tape is not suitable as a digital audio tape. ............. Order ............... (Please read the precautions on the back first Refill this page) Printed by the Staff Consumption Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs-31- This paper scale is applicable to the Chinese National Standard (CNS) A4 specifications (210x297 mm) V. Description of invention (30) Central Bureau of Standards of the Ministry of Economic Affairs Printed by employee consumer cooperatives

Table 2 Units Ex.6 Ex.7 CEx.4 CEx. 5 CEx. 6 Added particle types Cetaceous vaporized titanium vaporized titanium vaporized titanium vaporized titanium monodisperse silica particle size Μ 0.2 0.2 0.2 0.2 0.01 amount wtX 0.08 0.08 0.08 0.08 0.005 Base film properties_ Film thickness μ η 10 10 10 10 10 Surface roughness (Ra) nm 4.2 4.2 4.2 4.2 0.7 Stress at 5X elongation MD kg / BD 2 14.1 13.2 9.8 10.6 13.5 Residual elongation MD% 0.09 0.13 0.33 0.35 0.10 Residual elongation MD% 0.09 0.08 0.25 0.07 0.10 Thermal shrinkage (MD) 105CX 30ftir% 0.9 0.7 1.9 0.7 0.8 Percentage of non-defective products removed tb% 98 98 70 80 20 Tape properties Running durability-AA c CC

Ex. = Example, CEx. = Comparative example MD = Machine direction (= longitudinal) TD = Horizontal-to be wrapped- -32- This paper size uses the standard (CNS) A 4 specifications (210X297mm) (please first Read the precautions on the back and fill the nest page.-Binding and binding 5. Description of the invention (31) A6 B6

Table 2 (Wrapping)-Units Ex.8 CEx.7 CEx.8 Ex.9 CEx.9 Type of added particles-Vaporized titanium Vaporized titanium Vaporized titanium Vaporized titanium Vaporized titanium Particle size Μ 0.2 0.2 0.2 0.2 0.2 Amount wt% 0.08 0.08 0.08 0.08 0.08 Base film properties Film thickness M B1 8 8 8 6 6 Surface roughness (Ra) Π Gu 4.2 4.2 3.5 4.1 4.8 Stress at 5X elongation MD kg / nn 2 18.2 14.5 13.8 23.3 20.8 Residue Elongation MD% 0.03 0.23 0.22 0.05 0.28 Residual elongation TD% 0.11 0.31 〇.35 0.15 0.42 Heat shrinkage (MD) 105CX 30min% 1.1 2.9 D. 7 0.5 1.7 Percentage of non-defective products taken out 98 98 70 98 60 Tape nature lotus Transmitting durability-ACCAC (please read the precautions on the back before filling in this page) • Staple.-Printed by the Welfare Department of the Ministry of Economy Central Standards Bureau Employee Consumer Cooperative

Ex. = Example, CEx. = Comparative example MD = Machine direction (= Portrait) TD = Horizontal-3 3- This paper scale is applicable to China National Standard (CNS) A4 specifications (210X297 mm) Α6 Β6 Central Bureau of Standards, Ministry of Economic Affairs Printed by Beigong Consumer Cooperative V. Description of the invention (32) Examples and comparative examples. 10-12 Containing the inert particles of the poly-layer in Table 3 and having an intrinsic viscosity of () .65dl / g (at 25-C in the gas) Polyethylene terephthalate with a moisture content in phenol>, and polyethylene terephthalate containing inert particles of the second polyester layer in Table 3 and having an intrinsic viscosity of 0.65 dl / g were dried at 16 (rC, Then it was melted at 28ITC and co-extruded through a multi-manifold die at the ratio of the thickness / total thickness of the second polyester in Table 3. The extrudate was rapidly cooled / solidified on a beating drum at a temperature of 40 ° C to obtain Non-elongated laminated film. The above-mentioned non-elongated film is elongated with a draw ratio of Table 3 in the longitudinal direction and then with a stretcher in the longitudinal direction with a draw ratio of Table 3 between binary rods with different rotation speeds Then, the bi-stretched film was heat-treated at the heat setting temperature of Table 3, cooled at 90 ° C, and then taken out to obtain 10 thick biaxially oriented meals Polyethylene glycolate. Change the output of the two-dimensional extruder to adjust the thickness of the first polyethylene layer and the second polyester layer again. Furthermore, by fluorescent) [ray method and take out the sheet from the film and pass Transmission electron microscope observation method to find the interface, the thickness of each layer of Lan Dong. Then, the magnetic coating composition (the composition is described in (5) " Operation of magnetic tape ") is coated on the above biaxially oriented stack The surface of the first polyester layer of polyethylene terephthalate was obtained to obtain a recording tape β with a recording and playback time of 60 minutes. Table 3 shows the properties of the resulting film and magnetic tape. From Table 3, it is known that Examples 10 and 11 The resulting film has excellent handling properties, and the tapes obtained in Examples 10 and 11 have excellent durability. For comparison, because of the comparison -34- (please read the precautions on the back and then fill in this page). The paper scale is applicable to the National Sample Standard (CNS) Grade 4 (210x297 mm) of A country (A6 B6 321665) 5. Description of the invention (33) (please read the precautions on the back and fill in this page) Example 10 to 12 5% elongation in the machine direction shows low stress and / or high residual elongation Therefore, the magnetic tapes obtained in Comparative Examples 10 to 12 are elongated, causing the edge of the tape to buckle and fold. Furthermore, in the film obtained in Comparative Example 10, the surface roughness of the second polyester layer is low, so the magnetic tape exhibits poor running properties At the turn of the lotus, it wears out due to rough bumps. In the film obtained in Comparative Example 11, the surface roughness of the first and second polyester layers is high, so the magnetic tape shows the phenomenon that roughness is printed on the magnetic layer. The film obtained in Example 12 has a low surface roughness, and thus has poor processing properties, showing a poor percentage of non-defective products »Therefore, the films obtained in Comparative Examples 10 to 12 are not suitable as a base film for digital audio tapes. Example 1 2 and Comparative Examples 1 3 and 1 4 In the same manner as in Example 10, an unstretched laminated film was obtained in which the first polyester layer contained inert particles in Table 3 and the second polyester layer contained inert particles in Table 3. The unstretched lamination film was stretched and heat set under the conditions in Table 3, and cooled in the same manner as in Example 10. The unstretched lamination film was treated in the same manner as in Example 10 to obtain an 8 / in thick biaxial fixed vector vehicle Polyethylene terephthalate film and tape for recording and playback for 90 minutes. Table 3 shows the results of the film and tape obtained. The results of the film obtained in Example 12 were as good as those in Example 10. The films obtained in Comparative Examples 13 and 14 have a low stress and a high residual elongation when printed at 5% in the machine direction of the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy. Therefore, the tape is elongated, or the green tape causes folding and folding. " In other words, the film obtained in Comparative Example 13 exhibits large heat shrinkage. When used and stored in a high-temperature environment similar to summer, the magnetic tape undergoes large deformation, and thus is not suitable as a digital audio tape. -35- The size of this paper uses the Chinese National Standard (CNS) A4 specifications (210x297 mm) A6 B6 V. Description of the invention (34) Example 1 3 and Comparative Example 1 5 Obtained unstretched in the same way as Example 10 For the laminated film, the first polyester layer contains the inert particles in Table 3, and the second polyester layer contains the inert particles in Table 3. The unstretched laminated film is elongated and heat set under the conditions in Table 3 to obtain 6 # · Thick biaxially oriented laminated polyethylene terephthalate film and tape with a recording and playback time of 120 minutes. In Example 13, the heat-set biaxially oriented film was heated with a heating rod to 10 ° C, and then the film tension between the heating rod and the cooling rod was adjusted, and the longitudinal film heat shrinkage was 0.5% ^ Comparative In 15, the above adjustment is not performed. The results are shown in Table 3. The results of the film obtained in Example 13 are as good as in Example 10. β The film obtained in Comparative Example 15 has insufficient stress and high residual elongation at 5% elongation in the machine direction, so Because of wrinkling and folding β, the film obtained in Comparative Example 15 has a first polyester layer with a rough surface and exhibits large heat shrinkage, so it is not suitable for use as a digital audio tape. ............. Order ..................... # (Please read the precautions on the back and then iodine nest page) Printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs-36- This paper scale uses the National Standards (CNS) A4 specifications (210X297mm) of the country t A6 B6 5. Description of invention (35) Table 3 Unit Ex. 10 Ex. 11 CEx.10 Cohesive Length Length Degree ||, an inert diameter, length, width, length, and heat, the amount of seed particles, and then re-stratification, ester particles, 2 0 0, monodisperse sandstone, 0.2 0.07 200, monodisperse silicon Stone 0. 2 0.07 2 00 Monodisperse The thickness of the fermented grain of 0.2 stone layer is the thickness of the cohesive layer, the second inertia diameter, the second diameter, the total seed quantity, the seed quantity, and the seed quantity \ t μ η wt ϋ! Μ 丨 wt%% acid breaking. 0.15 10 7 loose 5 acid 20 points stone 4.1 carbon 丨 o single silicon οο 0 loose 5 acid 2.1 point stone 4.1 carbon ίϋ single silicon 00 degree layer of MDMDD) ni trap than the quality of rough ester ester D long length (M30 missing Thick and thick 丨 Polypropylene ΜExtending and contracting X No one hundred film surface Ra 21 1 5 Χ 力 余 收 5ec Produced a total table {第 在 应 残 残 热 10 取出 生产 μ η η η η η kg / m 2 %%%% 10 3.8 17.2 14.2 0.08 0.09 98 10 27.5 14.2 0.08 0.09 98 10 4.7 9. 2 11.4 0.29 0.21 0.9 90 Pack ........................... .tr ......................... # Please read the precautions on the back before filling this page} Printed by Beigong Consumer Cooperative of Central Bureau of Standards, Ministry of Economic Affairs

The nature of the tape is lotus-turnable and durable-AACIIC, square device, horizontal device, and vertical device. The paper size is applicable to China National Standards (CNS) Grade 4 (210X297 mm) 36 A6 B6 Central Standards of the Ministry of Economic Affairs Printed by Bureau Pongong Consumer Cooperative

Table) 3 (Wrapped) Units CEx. 1 1 CEx. 1 2 Ex. 12 Elongation Ratio Length-3.2 3. 9 5.0 寛 度-4.5 3. 8 3.6 Length (Re-Pulling-One--Long) Heat Setting Temperature ° C 220 175 200 Type of inert particles of the first polyester layer-monodisperse monodisperse monodisperse silica silica silica particle size μ m 0.2 0.01 0. 2 amount w 13! 0-1 0.005 0.1 second polyester layer Types of inert particles-calcium sulfonate monodisperse calcium sulfonate silica particle size 1.2 0. 2 0. 2 amount w 13! 0.25 0.1 0.1 Type-single point-single point silica silica particle size μ a 0. 4 — 0-4 Amount wt X 0.15-0.15 Second layer thickness /% of total thickness 80 10 10 Specific film properties Total film thickness Mn 10 10 8 Surface roughness (Ra) First polyester layer nm 10.5 0.7 4.2 Second polyester layer nn 4 5.0 5.2 2 7.5 kg / mm at 5 X elongation 2 10.6 12.4 19.1 Stress MD Residual elongation MD% 0.35 0.30 0.03 Residual elongation TD% 0.07 0.35 0.15 Thermal shrinkage (MD)% 0.7 1. 8 1 . 1 1 0 5eC X 3 0 ai η Take out without defects% 80 2 0 98 Product Percentage Tape Properties Continuous Rotation Durability-CCA Ε IC direction, square device to real machine horizontal = comparative example longitudinal) 38- To be wrapped .................. .................................................. ................. ^ :: 1…. 玎 | iii.i (please read the precautions on the back before filling in this page) This paper uses Chinese national standards Standard (CNS) A 4 specifications (210X297 mm) 37321665 A6 B6 V. Description of the invention (Table 3 (Wrapped unit CEX. 13 CEX. 1 4

Ex. 1 3 layer stretched W degree ester particle ratio {pan polymerization length degree degree} @ 一 mind class diameter elongated wide long and long hot first seed amount scattered 60 points stone 2.1 1 mono silicon 3. 8 250 monodisperse Sandstone 0.2 (Please read the precautions on the back before filling the nest page) Layer thickness of the ester grain thickness Polymer layer thickness Second inert diameter class diameter two total b The seed amount

μ.m vtX% calcium monobasic monodisperse silica 0.4 0.15 10 sulfonate 1.2 0. 1 monodisperse silica 0. 4 0.15 10 0 disperse acid 2.1 split stone 'mono 1 silica mono. MDMDD) ni sag is longer than the quality of the rough ester ester D long length (M30 insufficiency thick and thick) poly poly stretch M stretch stretch X no hundred film membrane surface Ra 2 15% force balance 52.5 Take the product at the residual heat 10 ^ i \ %%%% sk 8 4 5 4 2 1 0 0 3 8 6 -Subscription. Continued Printed by the Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs Ϊ IC direction, square device is more horizontal than vertical

A Wrap around the ruler and paper on paper

Ligong 97 2 X 321665 A6 B6 V. Description of the invention (38 Table 3 (Single ratio of ore-joining position; ffi polymerization length degree> @ 一 懒 类 圈 长长 宽宽 长长% Layered Ester Granules

Grain thickness of the polymer particles of the second type of inert particles of the second class, the amount of seed size, the thickness of the diameter ratio, the thickness of the layer, the total thickness of the layer, the NDoD of the layer, the depression ratio, the length of the rough ester, the length of the D, the length of the (M30 Insufficient thick and thick} Polypolypropylene ΜExtending and contracting X non-hybrid film surface Ral two 5% of the force and the remaining 5 ° 0 of the total production table {the first in the residual heat should be 10 Λί% Μ Β η Μ η should be kg / Β m %%%%

Good. Loose 5 Acid 2.1 Boulder 4.1 Master Ια single silicon 0D 6 27.8 18.5 0.23 0.40 1. 8 80 Pack ........................ Order ... ............ Silk (please read the precautions on the back and then this page) Printed by the Central Standards Bureau of the Ministry of Economic Affairs Beigong Consumer Cooperative Society Magnetic lotus

XDD ε NT Case comparison} One tfcK one-vertical. 11 X (EIC direction, square device to real machine horizontal paper size applies to China National Standards (CNS) A 4 specifications (210X297 mm) from 665 A6 B6 Ministry of Economic Affairs Printed by Beigong Consumer Cooperative of Central Bureau of Standards 39 5. Description of invention () Example 14 Contains 0.3% by weight of calcium nitrate (average particle size is 0.75 # B) and has an intrinsic viscosity of 0.62dl / g (at 25 ° C) (Measured in phenol), polyethylene 2,6-naphthalene dicarboxylate was dried at 170 eC, melt extruded at 300 ° C, and rapidly cooled / solidified on the drum at a temperature of 6fl ° C, resulting in a thickness of about 170 / ub The unstretched film is stretched 6 times in the longitudinal direction at 125 ° C between two sticks with different speeds, and then stretched 3.5 times in the transverse direction at 128 ° C with a tenter, Then heat-treated at 200 ° C for 1D seconds. Furthermore, the above-mentioned biaxially stretched film was floated in the furnace at 110 ° C to adjust the thermal shrinkage in the longitudinal direction to 0.3%. So 6-thick biaxially oriented poly 2 , 6-Naphthalene dicarboxylate film. Then, the magnetic coating composition (the composition of which is described in (5) " Permanence of lotus transfer of magnetic tape " Coated on the obtained biaxially oriented polyethylene 2,6- # dicarboxylate film, the tape β was obtained. Table 4 shows the properties of the obtained film and the tape. Table 4 clearly shows that the bottom film has excellent handling properties and the lotus turn durability of the tape is good Example 1 5 6 # thick biaxially oriented polyethylene 2,6-naphthalene dicarboxylate film and audio tape were obtained in the same manner as in Example 14, except that it was used for calcium monate particles to have an average particle diameter of 0.35 0.25% by weight Instead of monodisperse silica, and the heat setting temperature becomes 220 ° Ce. Table 4 shows the results, and Example 14 is equally good. -4 1- (Please read the precautions on the back before filling the nest page) λ 'book-embroider This paper is printed in Chinese National Standard (CNS) Grade 4 (210X297 mm) A6 B6 Printed by the Employees ’Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs 40 V. Description of Invention () Example 16 Obtained in the same way as Example 14 Long film, this unstretched film is stretched 2.3 times in the longitudinal direction at 130 ° C between two sticks with different speeds, and then stretched 4.3 times in the transverse direction with a tenter at 130 ° C, and then by Intermediate heat treatment at 16 Q ° C. Furthermore, the film is elongated at 170 ° C in the longitudinal direction 3. 0 times, elongated by 1.2 times in the transverse direction at 170 ° C, then heat treated at 215 ° C, and then subjected to the same floating heat treatment as in Example 14 to obtain 4 // B thick biaxially oriented poly 2, 6- # dicarboxylic acid ethylate The diester film and the tape with a recording and playback time of 180 minutes. Table 4 shows the results, which are as good as Example 14. Comparative Example 16 The unstretched film was obtained in the same manner as Example 14 and was obtained in the same manner as Example 14 6 # Thick biaxially oriented polyethylene 2,6-dicarboxylate film and tape, except that the unstretched film is stretched 4.8 times in the longitudinal direction between two sticks with different speeds at 125 ° C, and then A tenter was stretched 4.0 times in the transverse direction at 125 ° C, and then heat treated at 2fl0 ° C for 10 seconds without floating heat treatment. Table 4 shows the results. The base film has a high residual elongation, so Xue Zhong caused wrinkles and folds when the tape was running, showing high heat shrinkage. Therefore, when used and stored in a high temperature environment like summer, the tape is subject to large deformation. Audio cassette. Comparative Example 1 7 An unstretched film was obtained in the same manner as in Example 14, and a 6-thick biaxially oriented poly 2,6-naphthalenedicarboxylic acid ethylenedioxy film and Lu-4 2-(please first Read the precautions on the back and fill in the nest page.). Binding. Weft · The paper size is in accordance with Chinese National Standard (CNS) A 4 specifications (210X297 mm). A6 B6 printed by Beigong Consumer Cooperative, Central Bureau of Standards, Ministry of Economic Affairs 3. Description of the invention (41) The soundtrack, except that the unstretched film is stretched 4.5 times in the longitudinal direction between the two sticks with different speeds at 130 ° C, and then stretched 7.5 times in the transverse direction with a stenter 130 ° C, Then heat treatment at 201TC for 30 seconds without floating heat treatment. Table 4 shows the results. The base film has a high residual elongation in the longitudinal direction, so that the magnetic tape is elongated and causes wrinkles and folds when it turns, so the magnetic tape is not suitable as a digital audio tape. Comparison 18 A 4-thick biaxially oriented polyethylene 2,6-naphthalate film and tape were obtained in the same manner as in Example 16, except that no floating heat treatment was performed. Table 4 shows the results. The base film shows high residual elongation in the longitudinal and transverse directions, so the tape is seriously wrinkled and folded when it turns, so the tape is not suitable as a digital audio tape. "Comparative Example 1 9 6 # · thick biaxially obtained in the same way as Example 14 Oriented polyethylene 2,6- # dicarboxylate film and audio tape, except that the calcium monate particles are replaced by monodisperse silica particles with an average particle size of 0.05% by weight of 0.05 // 1, and the unstretched film is stretched in the lateral direction 4.0 times longer, the heat treatment time becomes 30 seconds, and no floating heat treatment is performed. Table 4 shows the result "The bottom film has a high residual elongation, so the tape runs (please read the precautions on the back and fill in this page). Installation:-Order. -Continued «Folded and wrinkled to make S 0 When the paper is stretched to the length of time, the paper size is based on the Chinese National Standard (CNS) A 4 specifications (210X297 mm) A6 B6 V. Description of invention (42) Central Standards Bureau of the Ministry of Economic Affairs Industrial and Consumer Cooperative Printed Table 4 Units Ex. 14 Ex. 15 Ex. 16 CEx. 16 Added particle type calcium monobasic monodisperse calcium monobasic calcium silicate calcium silicate particle size M a 0. 75 0.35 0.75 0.75 amount wtX 0.3 0.25 0.3 0.3 Base film properties- Film thickness M m 6 6 4 6 Surface roughness η plaque 14 7 12 16 (Ra) kg / na 2 extended at 5X 24.8 23.8 35.3 17.9 Stress MD Stress extended at 5X TD kg / ι · 2 16.1 15.6 18.7 12.4 Residual Elongation MD% 0.12 0.09 0.08 0.25 Residual elongation TD% 0.18 0.10 0.18 0.27 Thermal shrinkage (MD) 10 5 ° CX 30 * ir% 0.3 0.2 0.3 0.8 Percentage of non-defective products taken out 98 98 90 98 Tape properties Lotus turn durability -AAA c outfit ................... order ......... weft { (Please read the precautions on the back before filling the nest page)

Ex. = Example, CEx. = Comparative example MD = Machine direction (= longitudinal> TD = horizontal-to-be-wrapped- -44- This paper size is used + National Standards (CNS) A 4 specifications (210x297 mm): 43 V. Description of the invention () A6 B6 Printed by the Staff Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs

Table 4 (Wrapped) Units CEx. 17 CEx. 18 CEx.19 Type of added particles-calcium silicate calcium monobasic monodisperse silica particle size μ tB 0.75 0. 75 0.05 amount wtX 0.3 0.3 0.05 base film properties film thickness μ IB 6 4 5 Surface roughness (Ra) ηη 15 16 3 at 53: elongation stress MD kg / IBM 2 14.0 25.6 20.8 at 5Ϊ: elongation stress TD kg / nn 2 27.4 14. 3 10.8 residual elongation MD% 0.25 0.21 0.18 Residual elongation TD% 0.14 0.32 0.23 Heat shrinkage (MD) 10 5 ° CX 30nir% 0.6 0.4 1. 5 Percentage of non-defective products taken out% 98 98 30 Tape properties Lotus turn durability-B c C

Ex. = Example, CEx. = Comparative example MD = Machine direction (= Portrait) TD = Horizontal-45- This paper scale is applicable to the Chinese Standard (CNS) Grade 4 (210X297mm) (Please read the note on the back first (Fill in this page again)

Printed by the Ministry of Economic Affairs, Central Habitat Bureau, Beigong Consumer Cooperatives. Example 17 contains 0.1% by weight of monodisperse silica particles (average particle size is fl.12 # «〇 and has an intrinsic viscosity of 0. S 2 d 1 / g (at 2 5 (Measured in o-phenol), 2,6-naphthalene dicarboxylic acid ethylene glycol is dried at 170 ° C, melt-extruded at 300-(3, and quickly cooled on the drum at 60 * Cjg, producing about 160 // · Thick unstretched film. The above unstretched film is stretched 5.8 times in the longitudinal direction between two slap sticks with different speeds at 125 T, and then stretched in the transverse direction by a stenter at 125 " C 4. 5 times, and then heat treated in 2D0-C for 10 seconds. Furthermore, the above biaxially elongated film was subjected to floating heat treatment in a furnace at 110 ° C to adjust the thermal shrinkage in the longitudinal direction to 0.3%. So 6 # η thick was obtained The biaxially oriented polyethylene 2,6-naphthalene dicarboxylate film. Then, the same reverse coating composition as used in Example 6 was applied to the resulting biaxially oriented polyethylene 2,6-naphthalene dicarboxylate film. On the surface, a 1.2-meter-thick reverse coating is formed. Then, the magnetic coating composition (the composition of which is described in (5) " Operational durability of the magnetic tape ") is coated on the biaxially oriented poly 2, 6-Naphthalene dicarboxylate film, a tape with a recording and playback time of 120 minutes is obtained. Table 5 shows the properties of the above film and tape. Table 5 clearly shows that the bottom film has excellent processing properties and the tape operation is good for long-term operation 》 Example 18 An unstretched film was obtained in the same manner as in Example 17, the unstretched film was stretched 2.2 times in the longitudinal direction between two sticks with different speeds at a temperature of 13fl ° C, and then a stenter was used at 130 « C is elongated 4.1 times in the horizontal direction, and then from the middle hot spot (please read the precautions on the back before filling the nest page). Packing: -Order: Thai paper * Standard to use Chinese Sleeping Standard (CNS) A 4 specifications (210X297mm) A6 B6 Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economy V. Description of invention (45) Reasonable at 160 ° (: heat treatment. Furthermore, this film is 170 ° 0: elongated 3.2 times in the longitudinal direction, at It is elongated at 170 ° C in the transverse direction by 1.2 times, and then heat treated at 215 ° C, and then subjected to the same floating heat treatment as in Example 17, to obtain a 4 / zb thick biaxially oriented polyethylene 2,6-naphthalate film and recording And a tape with a playback time of 180 minutes. Table 5 shows the result, which is as good as Example 17. Comparative Example 2 0 In the same manner as in Example 17, a 6 # m thick biaxially oriented polyethylene 2,6-dicarboxylate film and tape were obtained, except that the unstretched film was at 125-C temperature between dip rolls with different speeds. Longitudinal stretch 5.0 times, then stretcher 4.2 times in the transverse direction at 125eC, and then heat treatment at 205 ° C for 10 seconds without floating heat treatment. Table 5 shows the results. The bottom film has a high residual elongation, so the tape turns It causes severe wrinkles and folds, and shows high heat shrinkage. Therefore, when used and stored in a high temperature environment similar to summer, the tape is subject to large deformation. Therefore, the magnetic tape is not suitable as a digital audio cassette. Comparative Example 2 1 4 // B thick biaxially oriented polyethylene 2,6-carboxylate film and tape were obtained in the same manner as in Example 18, except that the unstretched film was heat-treated at 250 ° C for 30 seconds Without floating heat treatment. Table 5 shows the results. The base film has a high residual elongation in the longitudinal and lateral directions, so when the tape turns, the edge of the tape warms and causes wrinkles and folds. Therefore, the magnetic tape is not suitable for digital audio tapes. -47- ................................................... green_ (Please read the precautions on the back before filling the nest page) This paper uses the Chinese National Standard (CNS) A4 specifications (210X297 mm). The A6 B6_ 46 is printed by the Beigong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs. Description () Comparative Example 2 2 A 6 // thick biaxially oriented polyethylene 2,6-sebacate film and tape were obtained in the same manner as in Example 17, except that the silica particles had a 0.01AB average particle diameter of 0.01 Instead of weight percent monodisperse silica particles, heat treatment was performed at 160 ° C for 30 seconds without floating heat treatment. Table 5 shows the results. The base film has a high residual elongation, so the tape lotus causes serious wrinkles and folds when it turns, so the film is not suitable as a base film for several p recording tapes. .................................................. .................................. Pretend .............. ......... ΤΓ ....................._ (Please read the precautions on the back before filling in this page) The size of this paper Printed in the National Standards (CNS) Grade 4 (210X297 mm) V. Description of invention (47) A6 B6 Printed by the Staff Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs

Table 5 Unit Ex · 17 Ex. 1 8 CE x. 2 0 Type of added particles-Monodisperse Monodisperse Monodisperse Silica Silica Particle size μ twist 0.12 0.12 0.12 Amount W t X 0.10 0.10 0.10 Base film properties Film thickness M ffi 6 4 6 Surface roughness nm 4.5 4.2 4.5 (Ra) kg / me2 at 5 X elongation 2 3.5 34.4 18.5 Stress Μ D kg / me at 5X elongation 2 17.0 17.5 14.2 Stress TD Residual elongation MD% 0.12 0.09 0.22 Residual stretch STD% 0.18 0.10 0.30 Heat shrinkage (MD)% 0.3 0. 2 0,8 1 0 5 ° CX 3 0 mi η Take out defect-free% 98 98 98 Product percentage Tape properties Lotus turn durability-AAC

Ex · = Example, CEx. = Comparative example MD = Machine direction (= longitudinal direction) TD = Landscape-to be conspicuous- -4 9- This paper scale uses the National Standards (CNS) A4 specifications (210x297 mm) of this paper. .................................................. ................................. install ............... ........ May ..................... Darts (please read the precautions on the back before filling the nest page) 5. Description of the invention ( 48) A6 B6 Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs

Table 5 (connected) Unit CEx. 2 1 CE x. 2 2 Type of added particles-monodisperse monodisperse silica silica particle size M «0.12 0.01 amount W t% 0.10 0.01 Base film properties Film thickness # 鼸 4 6 Surface Coarseness η η 4.5 0.8 (Ra) kg / aa at 5 X elongation 2 2 6.4 19.5 Stress MD at 5 X elongation kg / m 2 22.0 13.5 Stress TD residual elongation MD% 0.20 0.28 residual elongation TD% 0.34 0.36 Heat shrinkage (MD)% 0.5 1. 5 0 1 0 5 CX 3 0 η 1 η Take out without defects% 98 30 Product percentage tape properties lotus transfer time-CC

Ex. = Example, CEx. = Comparative example HD = Machine direction (= Portrait) TD = Landscape -5 0-This paper scale adopts China National Standard (CNS) A4 specification (210X297mm)

.................................................. .................................. Pretend .............. ........ Order ..................... Line _ {Please read the precautions on the back before filling the nest page J 321665 A6 B6 Economy Printed by the Employee Consumer Cooperative of the Central Bureau of Standards of the Ministry 5. Description of Invention (49) Examples 19-20 and Comparative Examples 23-25 contain lubricant particles as the first polyester layer particles in Table 6 and have an intrinsic viscosity of 0.62 (11 ^ ( (Measured in 250mg of fumophenol) poly (2,6-carbodicarboxylate) particles and the same poly (2,6-pyrene) containing lubricant particles as the second polyester layer particles of Table 6 The pellets of ethylene formate were dried at 170 ° C and then melted at 3fl0 ° C. At the ratio of the thickness / junction thickness of the second polymer layer in Table 6, they were co-extruded through a multi-pipe die. Cooling / solidification on the binding drum at a temperature of 6G ° C, resulting in an unstretched lamination film with a thickness of about 130 to 170 # η. The unstretched film is placed between two boat sticks with different speeds in the longitudinal direction. The length is longer, and then the tenter is used to stretch in the horizontal direction than in Table 6. Then, double The elongated film was heat-treated at the heat setting temperature of Table 6. Except for Comparative Example 23, the heat-treated film was further subjected to a floating heat treatment in a furnace at 1100 ° C to adjust the thermal shrinkage in the longitudinal direction to 0.2%. Then, the resulting thick Biaxially oriented lamination Xing 2,6-sebacate ethylene dicarboxylate film. In Comparative Example 23, 6yUB thick biaxially oriented lamination film was also taken out without performing the above-mentioned floating heat treatment. The output of the two-value extruder was changed To adjust the thickness of the first polyester layer and the thickness of the second polymer layer. Furthermore, the thickness of each layer is measured by the fluorescent X-ray method and the method of removing the sheet from the film and observing through a transmission electron microscope to find the interface. , The magnetic coating composition (the composition of which is described in (5) " Lane Turning Durability of Magnetic Tape ") is coated on the surface of the first polyester layer of the biaxially oriented lamination film, and the recording and playback time is 1 2 fl minutes of audio tape. -5 1-(Please read the precautions on the back before filling the nest page) This paper uses the National Standard (CNS) Grade 4 (210X297 mm) A6 B6 Central Ministry of Economic Affairs Printed by the Bureau of Standards and Staff Consumer Cooperative V. Description of the invention (50) Table 6 shows the properties of the obtained film and magnetic tape. It is known from Table 6 that the base films obtained in Examples 13 and 20 have excellent handling properties, and the magnetic tapes obtained in Examples 19 and 20 have excellent lotus transfer durability. In comparison, the films obtained in Comparative Examples 23 to 25 have high residual elongation, so the tape is stretched during operation, causing wrinkles and folds. These results show that all the tapes obtained in Comparative Examples 23 to 25 are not suitable for digital audio tapes. Bottom film. Example 2 1 and Comparative Example 2 6 In the same manner as in Example 19, an unstretched laminated polyethylene 2,6-dicarboxylate film was obtained, the first polyester layer of which contained inert particles in Table 6, and the second polyester The layer contains the inert particles of Table 6. The unstretched laminated film is stretched in Table 6 more than biaxially stretched and heat set in the heat setting temperature of Table 6. In Example 21, the elongated laminated film was subjected to the same floating heat treatment as in Example 19 to adjust the thermal shrinkage in the longitudinal direction to 0.2%, while in Comparative Example 26, the upper floating heat treatment was not performed. Separately, 4 // B thick biaxially oriented laminated polyethylene 2,6-naphthalene dicarboxylate films were obtained. The magnetic coating composition was applied to the surface of the first polyester layer of each film in the same manner as in Example 19 to obtain a tape having a recording and playback time of 180 minutes. Table 6 shows the results. The results of the film obtained in Example 21 are as good as in Example 19. The film obtained in Comparative Example 26 had high residual elongation in the machine direction and the transverse direction, so that the tape edge caused wrinkling and folding when the tape was running. Furthermore, the film obtained in Comparative Example 26 showed large heat shrinkage, and thus the magnetic tape was greatly deformed in a high-temperature environment. Furthermore, since the thickness ratio of the second polyester layer is high, the surface of the first polyester layer is rough. -5 2-^ ........................................................ _ (Please read the precautions on the back before filling in this page) The paper size is applicable to the national standard (CNS) f4 specification (210X297 mm) of country t. 5. Description of the invention (51 ·) A6 B6 Bei Gong, Central Standards Bureau, Ministry of Economic Affairs Printed by consumer cooperatives

Table 6 Units Ex. 19 E x. 2 0 CEx. 23 Elongation ratio-length-6.0 2. 2 5. 5 width-4.3 3.9 4. 2 length (re-draw--2. 8-long) width ( Re-pulling--1.15-long) Heat setting temperature ° C 2 10 2 10 160 Type of inert particles of the first polyester layer-monodisperse monodisperse monodisperse silica silica silica particle size M m 0. 2 0. 2 0.2 amount wt X 0.07 0.07 0.07 Type of inert particles of the second polyester layer-calcium sulfonate calcium sulfonate calcium silicate calcium particle size β i 0.8 0. 8 0. 8 amount wt% 0.15 0.15 0.15 type-monodisperse Dispersed monodisperse silica silica silica particle size μ a 0. 2 0. 2 0 · 2 amount wt X 0.07 0.07 0.07 Second layer thickness /% of total thickness 10 10 1 0 Specific film thickness Total film thickness μ n 6 6 6 Surface roughness (Ra) First polyester layer nm 4 .0 3. 7 4. 4 Second polyester layer η n 2 4.1 2 3 · 6 24.8 kg / mu 2 extended at 5 X 24.4 2 5.7 2 0.8 Stress MD at 5 3! Kg / channel of elongation 2 14.6 16.3 12.4 stress TD residual elongation MD % 0.11 0.09 0.32 Residual elongation MD% 0.19 0.18 0.41 Heat shrinkage (MD)% 0. 2 0.2 1.6 1 0 5 ^ CX 3 0 »i η Take out non-defective% 98 98 98 -A A. C Ε IC direction, square device to the actual machine horizontal example is more than the vertical entanglement ......................... Order ... ................. green (please read the precautions on the back before filling the nest page) This paper size is applicable to the Chinese National Standard (CNS) A 4 specifications (210x297 mm ) A6 B6 Printed by Beigong Consumer Cooperative, Central Bureau of Standards, Ministry of Economic Affairs

l · 6 (Wrap unit CEx-24 CE x. 2 5 E x. 2 1 Elongation ratio length-4.5 5 6.0 2. 2 Width-5. 0 4. 3 3.85 Length (re-pull---3. 2 Length) Width (Re-drawing---1.2 Length) Heat setting temperature ° c 200 2 50 2 2 0 Type of inert particles in the first polyester layer-Monodisperse monodisperse monodisperse silica silica silica particle size M m 0. 2 0. 2 0.2 Amount wt% 0.07 0.07 0.07 Type of inert particles of the second polyester layer-monodisperse silica calcium masterite silica particle size M B 0.2 1. 0 0. 8 Amount W t% 0.07 0.5 0.15 Type---Single fraction silica particle size μ ffi--0.2 amount W t%--0.07 Second layer thickness /% of total thickness 10 80 10 fcb Base film properties Total film thickness μ R 6 6 4 Surface roughness Degree (Ra) The first polyester layer nlu 0. 8 12.1 3.5 The second polyester layer nil 9. 7 48.0 2 2.7 kg / elongation at 5¾ π 2 14.8 2 1.6 2 7.5 stress MD at 5 X elongation kg / m · 2 17.3 12.0 16.2 Stress TD residual elongation MD% 0.22 0.27 0.09 Residual elongation TD% 0. 17 0.39 0.12 Heat shrinkage (MD)% 0. 2 0.2 0. 2 1 0 5 ° CX 3 0 1 i η Take out non-defective% 30 80 98 Product percentage Tape properties Lotus turn durability-c CAEIC direction, square device direction The actual machine is more horizontal than the vertical entanglement ....................................................... ... Weft. (Please read the precautions on the back before filling the nest page) This paper uses the National Standard (CNS) A 4 specifications (210X297 mm) 321665 A6 B6 for the size of the paper. 5. Description of the invention ( ) Printed by Beigong Consumer Cooperative of Central Bureau of Standards, Ministry of Economic Affairs

Table 6 (Wrapped) Unit CE x. 2 6 Elongation ratio Length Width Length (re-elongation) Width (re-elongation) Heat setting temperature Type of inert particles of the first polyester layer Particle size ° c Μ »wt X 6.0 4. 3 180 Monodisperse silica 0. 2 0.07 Inert particles of the second polyester layer-type-calcium sulfonate particle size um 1.8 amount wt% 0.15 type-monodisperse silica particle size B 0. 2 Amount W t% 0.07 Second layer thickness /% of total thickness 90 Ratio of base film properties Total film thickness M Tian 4 Surface roughness (Ra) First polyester layer ns 10.5 Second polyester layer nm 24.3 at 5 3: Elongation Kg / m »2 2 3.4 Stress MD at 5 X elongation kg / am 2 12.5 Stress TD Residual elongation MD% 0.25 Residual elongation MD% 0.32 Heat shrinkage (MD)% 1.1 1 0 5 ° CX 3 0 ni η Take out none Defect% 98 Product Percentage Tape Properties Lian Zhuan Durability-C CE-directed, square-shaped device to real-machine horizontally-oriented standard paper standard used in the national standard (CNS) A 4 specification (210X297 mm) (please (Read the precautions on the back before filling this page)- Binding

Claims (1)

A8 B8 • Ten · C8 D8 patent application No. 83102190 Fan Guxi "Magnetic tape for digital recorder cassettes and its _ directional poly cool base film j patent case (amended on September 17, 86) I ii» ui ^ i ^^ 1 ^^ 1 Ml 1 ^ 1 in — ϋ ϋ— (please read the $ item on the back and then fill in this page) Scope of patent application: 1. A biaxially oriented polyester base for magnetic tape of digital recorder cassettes The die, its waiting is: (a) When the biaxially oriented polyester base film is stretched at 5% in the direction, the stress is at least 12kg / b 丨 2, (b) The residual elongation in the direction is 0.2% or less, transverse The residual elongation is 0.3% or less, (c) at 105 t: after 30 minutes of no-load heat treatment, the thermal shrinkage in the longitudinal direction is 1.5% or less, (d) at least one surface of the biaxially oriented polyester base film has 25η · Or the following surface roughness Ra, (e > Fanyuan with a film thickness of 3 to 12 / z *. 2. The biaxially oriented polyester base film as stated in item 1 of the Shenli range, where the biaxially oriented polymer When the ester base film is stretched in the longitudinal direction by 5%, the plaque force is in the range of 12 to 15 kg / η · 2, the residual stretch in the longitudinal direction is 0.15% or less, and the film thickness is in the range of 9 to 12 iui. Printed by Yigong Consumer Cooperative, Central Bureau of Standards, Ministry of Economic Affairs 3. Biaxially oriented polyester base film as claimed in item 1 of the patent scope • When the biaxially oriented polyester base film is elongated by 5% in the longitudinal direction, the stress is between 15 and 20 In the range of kg / »» 2, the residual elongation in the longitudinal direction is 0.15% or less, and the film thickness is in the range of 6 to 9 wb. 4. For example, the biaxially oriented polyester base film in item 1 of the Shenli range, where the double The axially oriented polyester base film has a stretch force of at least 20 kg / BJP2 at a longitudinal elongation of 5%, a residual elongation in the longitudinal direction of 0.15% or less, and a film thickness I in the range of 4 to 6 -56 «« Family Practice Standard (CNS) Regulation A4 ^ (210x297mm) 3々6β5 as ν Β8 ----------- VI. Application for a patent model garden 5. If applying for patent model item 1 Biaxially oriented polyester base film, wherein at least one surface of the film has a Ra of 5 to 25nn. 6. The biaxially oriented polyester base film as claimed in item 1 of the patent application, wherein the surface of the film is provided with Lubricity is given to the reverse coating, and the Ra on the other surface of the film is 8η · or less. 7 · Biaxially oriented polyester base film as in patent application No. 1 in which Poly® is Ethylene terephthalate. 8 ~~ Single-axis oriented polyester base film used in the magnetic box of the digital recorder cassette, its special features are: (a) When the biaxially oriented laminated polyester base film stretches in the longitudinal direction At 5%, the stress is at least 1 2 kg / id 2, (b > the residual elongation in the longitudinal direction is 0.2% or less, and the residual elongation in the transverse direction is 0.3% or less, (c) After 30 minutes of unloaded heat treatment at 105¾, the longitudinal The heat shrinkage is 1.5% or less. (D) The first polyester layer with Ra of 8η · or less and the second polyester layer with Ra in the range of 8 to 48η β are the outermost layers. Printed by Beigong Consumer Cooperatives H--L. 1 ^ 1 ^^ 1 in In n · ϋ —Βϋ i ^ i (please read the note on the back first before filling in this page) (e) IIH film thickness is 3 Up to 12 «b. 9. The biaxially oriented polyester base film as claimed in item 8 of the patent application, wherein the first polyester layer provides the surface on which the magnetic layer is formed. 10. The biaxially oriented polycool base film as claimed in item 8 of the patent scope, in which the Ra of the second polyester layer is in the range of 10 to 40na. 11. For example, the biaxially oriented polyester base film of patent application No. 8 of which the -57- paper size is used in the middle-sleepy country (CNS) A4C # (210X297mm) S21665 A8 B8 C8 D8 The thickness of the second polyester layer in the patent application range is 5 to 50% of the thickness of the laminated polyester base film. (Please read the note $ item on the back and then fill in this page) ..: 12. For example, the biaxially oriented polyester base film of item 8 of the patent scope, in which the biaxially oriented polyester base film stretches in the longitudinal direction 5 %, The stress is in the range of 12 to 15 kg / Bin2, the residual elongation in the longitudinal direction is 0.15% or less, and the film thickness is in the range of 9 to 12 // ·. 13. The biaxially oriented polyester base film as claimed in item 8 of the patent application, wherein when the biaxially oriented laminated polyester base film is elongated in the longitudinal direction by 5%, the stress is in the range of 15 to 20 kg / anD2; the residual extension in the longitudinal direction It is 0.15% or less, and the film thickness is in the range of 6 to 9 «β. 14. The biaxially oriented polyester base film as claimed in item 8 of the patent scope, wherein when the biaxially oriented laminated polyester base film is elongated in the longitudinal direction by 5%, the stress is at least 20 kg / mm2, and the residual elongation in the longitudinal direction is 0.15% or Below, the film thickness is in the range of 4 to 6 «. 15. The biaxially oriented polyester base film as claimed in item 8 of the patent scope, in which the polyester of the first polyester layer and the second polyester layer are both polyethylene terephthalate. 16. A kind of biaxially oriented polyethylene 2,6-naphthalene dicarboxylate base film used in the cassettes of digital recorders. Its special features are: Printed by the Zhenggong Consumer Cooperative of the Central Bureau of Standards of the Ministry of Economic Affairs (a ' ) When the biaxially oriented polyester base film is elongated in the longitudinal direction by 5%, the stress is at least 23kg / mB2, (b) the residual elongation in the longitudinal direction is 0.2% or less, and the residual elongation in the transverse direction is 0.3% or less, (c ' ) After 105 minutes of no-load heat treatment for 30 minutes, the thermal shrinkage in the longitudinal direction is 0.5% or less. This paper uses the Chinese National Standard (CNS) Α4 specification (210X297 mm) Patent application range (d) At least one surface of the biaxially oriented polyester base film has a surface roughness Ra of 25η or less, and (e ’) the film thickness is in the range of 3 to 6. For example, the biaxially oriented polyethylene 2,6- # dicarboxylate base film of patent application No. 16 has a residual elongation in the longitudinal direction of 0.15% or less. 18. For example, the biaxially oriented polyethylene 2,6-naphthalene dicarboxylate base film according to item 16 of the scope of application, wherein when the film is elongated in the lateral direction by 5%, the force should be at least 12kg / min. The biaxially oriented poly (ethylene 2,6-dicarboxylate) base film of the item, wherein at least the surface Ra of the film is in the range of 5 to 25 η π. 20. The biaxially oriented polyethylene 2,6-dicarboxylate base film as claimed in item 16 of the patent application, wherein one surface of the film is provided with a lubricity-imparting coating on the reverse side, and the other surface has 8η · or The following Ra. 21. A biaxially oriented polyethylene 2,6- # dicarboxylate base film for magnetic tapes of digital recorder cassettes. Its special features are: Central Bureau of Standards of the Ministry of Economic Affairs®: Industrial and Consumer Cooperative Printed ft ( Please read the note $ item on the back before filling in this page) (a ·) When the biaxially oriented laminate bottom film is elongated in the longitudinal direction by 5%, the stress is at least 23kg / · B2, (b) The residual longitudinal extension in the longitudinal direction is 0.2% or Below, the residual elongation in the transverse direction is 0.3% or less, (c ') After 30 minutes of no-load heat treatment at 105¾, the thermal shrinkage in the longitudinal direction is 0.5% or less, (d') The first polymer with Ra of 8η · or less The ester layer has a size of 8 to _ 5 9-This paper scale uses the Chinese National Standard (CNS) A4 specification (210X297 mm) MB of the Central Bureau of Standards of the Ministry of Economic Affairs; A8 B8 C8 D8 printed by the industrial and consumer cooperatives. The second polyester layer of the solid 40η · Fan Xizhi Ra is the outermost layer. The polyesters of the first and second poly-cooling layers are both polyethylene 2,6-naphthalene dicarboxylate, with a film thickness of 3 to 6 « Scope. 22. The mandrel-oriented polyimide 2,6-hexanedicarboxylate base film as claimed in item 21 of the patent scope, wherein the first polyester layer provides the surface on which the magnetic layer is formed. 23. The biaxially oriented man-made polyethylen 2,6-hydroxydicarboxylate base film according to item 21 of the patent application, wherein the Ra of the second polyester layer is in the range of 10 to 40πβ. V 24. The biaxially oriented JIH poly 2,6-ethylene dicarboxylate base film as claimed in item 21 of the patent application, wherein the thickness of the second polyimide layer is 5 to 50 of the thickness of the stacked poly base film %. 25. The biaxially oriented laminated polyethylene 2,6-naphthalene dicarboxylate base film as claimed in item 21 of the patent scope, wherein the residual elongation in the longitudinal direction is 0.15% or less. 26. Biaxially oriented "H poly 2,6-ethylene dicarboxylate base film as claimed in item 21 of the patent scope, where the stress is at least 12 kg / iBB2 when the stacked M film is elongated in the lateral direction by 5%. 27. A type of magnetic tape used in digital audio cassettes, including the biaxially oriented polyester base film as claimed in item 1 of the patent scope and the magnetic layer formed on one surface thereof. 2 8. A magnetic tape for a digital audio cassette as claimed in item 27 of the patent scope, wherein the lubricity is imparted to the reverse surface coating formed on the other surface of the biaxially oriented polyester base film. -60- The size of this paper adopts China National Standard (CNS & A4 specification (210X297mm) ------------ installed ------ ordered ------ -^ (Please read the note $ item on the back and then fill out this page) 321665 Α8 Β8 C8 D8 VI. Patent application scope 29.-A type of magnetic tape used for digital audio cassettes, including dual-axis such as patent application item 8 Oriented polyester base film and magnetic layer formed on the surface of the first polyester layer. 30.-A magnetic tape for digital audio cassettes, including biaxially oriented poly 2,6-as in patent application item 16. Ethylene naphthalate base film and the magnetic layer formed on one surface of it. 31. The magnetic tape used for digital audio tape cassettes as claimed in item 30 of the patent application range where the lubricity imparts the reverse coating formed on the double Axis-oriented poly 2,6-ethylene phthalate base film on the other surface. 32.-A magnetic tape used in digital audio cassettes, including biaxially oriented βΗ 聚 2 as in claim 21 6-Naphthalene dicarboxylate base film and the magnetic layer formed on the first polyester layer. (Please read the note $ item on the back before filling this page) Central Standards of the Ministry of Economic Affairs Negative consumer cooperative work printing equipment -61-- this paper Le Bu with the Chinese national scale quasi rub (CNS) Α4 size (210X297 mm)