JPS5936129A - Magnetic recording item - Google Patents

Abstract

PURPOSE:To obtain titled item of high dimensional stability to moisture absorption, by providing a magnetic layer on a flexible substrate constituted by a polyester with specific intrinsic viscosity, the amounts of the terminal hydroxyl and carboxyl groups totalling a specific value or lower, also free from hydrophilic group. CONSTITUTION:A polyester (mainly constituted by a recurring unit such as ethylene terephthalate) with an intrinsic viscosity >=0.4, the amounts of the terminal hydroxyl and carboxyl groups totalling <=90wt% of that of the whole terminal group, also free from hydrophilic group is subjected to an extruder, etc. to deliver on the casting drum to effect quenching, thus obtaining a virtually undrawn film. This film is subsequently subjected to multistage drawing at least unidirectionally and, if required, heat-treated to produce a flexible substrate. On either or both surface of the substrate, a blend of a magnetic material (e.g., of iron oxide-modified type) and binder consisting mainly of organic polymer is coated to obtain the objective item.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording article in which a magnetic layer is provided on one or both sides of a flexible support such as a polyester film or T-sheet, and further includes: Specifically, the present invention relates to a magnetic recording article having a flexible support made of polyester having low hygroscopicity and thus improved hygroscopic dimensional stability.

Conventionally, polyethylene tele-7 tallate biaxially stretched film has been used for magnetic recording articles such as magnetic tapes, etc. due to its excellent mechanical properties, heat-resistant dimensional stability, and chemical resistance.
It is widely used in magnetic cards, floppy disks, etc. The basic physical properties required for the base film for magnetic tapes include its surface properties (slip properties, surface smoothness, abrasion resistance, grains free of foreign matter, etc.), and mechanical properties (resistance to minute deformation - Young's modulus). , strength, residual elongation, creep properties, film stiffness, etc.), heat resistance and dimensional stability, etc. By the way, as devices become more sophisticated, precise, and compact, recording magnetic materials are also becoming more dense. As a result, the dimensional stability of the support, which is the basis of the magnetic recording medium, has become an important non-Ic physical property.

Regarding magnetic recording article buttons, dimensional stability as well as mechanical properties are important physical property values. Regarding magnetic recording articles using polyester supports, dimensional stability due to heat (e.g., heat shrinkage, changes in flatness) has been studied from various angles, but little is known about dimensional changes due to moisture absorption. It has not been done. The reason for this is that polyester inherently exhibits low moisture absorption, but now dimensional stability accompanying moisture absorption has also become an important physical property in industry.

[ 7 things.

That is, the present invention provides a magnetic recording article in which a magnetic layer is provided on one or both sides of a flexible support made of polyester, in which the polyester has an intrinsic viscosity of 0.4 or more, and the sum of terminal hydroxyl groups and carboxyl groups is This is a magnetic recording article characterized by having a terminal group amount of 90φ or less and not containing a hydrophilic group.

In the present invention, polyester refers to a polyester whose main repeating unit is ethylene terephthalate or ethylene-2,6-naphthalate, and its acid component and/or
Or, some of the glycol components may be combined with these mutual acid components and/or
Alternatively, it may be replaced with other acid components or other glycol components. Examples of such third components are isophthalic acid and 1,5-naphthalene dicarboxylic acid.

2.7-naphthalenedicarboxylic acid, 4.4'-diphenyldicarboxylic acid, 4.4'-diphenoxyethanedicarboxylic acid, 4.4'-Q enylsulfone dicarboxylic acid 7
Acid, 4,4'-diphenyl edel dicarbon m +
p-β-hydroxyethoxybenzoic acid.

Adipic acid, aze2ic acid, cepatic acid, hexahydrotereheptadalic acid, hexahydroisophthalic acid 1g-oxycaproic acid, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene/glycol.

Neopentylene gellicol, 1.1-cyclohexane dimetatool, 1.4-cyclohexane dimetatool, 2
, 2-bis(4-β-hydroxyethoxyphenyl)globan, bis(4-β-hydroxyethoxyphenyl)
Examples include sulfones and functional derivatives thereof.

The polyester may contain one [or two or more] of these, and the polyester may contain, for example, pentaerythritol, trimethylolpropane, trimellitic acid, trimesic acid, and functional IIv thereof, to the extent that the polyester is substantially cotton-like. lfi of polyfunctional compounds such as conductors etc. 2 and/or 0-benzoyl benzoyl rP! , methoxypolyethylene glycol and functional derivatives thereof may be copolymerized.

Polyester V- has stabilizers (e.g. heat, ultraviolet light.

Stabilizer against oxygen), stabilizer 1, filler.

Additives such as a mold release agent, anti-shingling agent, and nucleating agent may be added, but it is preferable to use highly stable additives.

In the present invention, the above-mentioned polyester is polymerized at 12% by a conventional method to form a molten fR film and stretch it to produce a base film or a sheet-like material that becomes a flexible support at any stage. By setting the total amount of terminal hydroxyl groups and carboxyl groups to 90% or less, preferably 60% or less, more preferably 40% or less, and most preferably 20% or less of the total amount of terminal groups, moisture absorption dimensional stability is particularly important. This makes it possible to apply the present invention to supports for magnetic recording articles with improved properties and even higher precision. The present invention is not limited to the means itself for converting this terminal group to make it inert to moisture. In a most suitable method, for example, diphenyl carbonate, dicyclohexenyl acetate, tetraphenyl orthocarbonate, diphenyl terephthalate, and diphenyl oxalate can be treated at a stage where the degree of polymerization has increased to a certain degree before the completion of polymerization. There is a method of adding an appropriate amount of an end-capping agent such as the following, and reacting with the active end group. Alternatively, the number of carboxyl groups can be increased in advance, and diazomethane treatment can be performed in the form of a molded product or an intermediate (for example, a polymer powder or pellet) to reduce the number of active terminal groups. This method is difficult to put into practical use due to problems such as slow reaction and toxicity of chemicals, but in addition to adding an end-blocking agent, it is possible to treat the ends of the polyester so that no hydrophilic groups remain. It becomes necessary. Here, the hydrophilic group is copolymerized with polyethylene glycol' or 5-sulfoisophthalic acid component, or a group such as a urethane group or an amide group is introduced as a result of an end-blocking process.

It is essential that the polyester used as the flexible support used in the present invention has an intrinsic viscosity of 0.4 or more when measured in orthochlorophenol at 35°C. If the intrinsic viscosity is below this range, the molecular weight is low, so it is not practical to make into an emergency pressure film.

In the present invention, formation into a sheet or film can be carried out by conventionally known methods.

That is, Tivolimer is melt-extruded using an extruder or the like and quenched on a recasting drum, and this substantially unstretched film-like material is subjected to one or more stages of stretching in at least one direction,
Heat treatment or relaxation treatment under unreasonable conditions is performed as necessary. Recent magnetic recording conditions require magnetic recording materials to have even higher Young's modulus and dimensional stability, and Young's modulus can be accommodated in a wider range through multi-stage high-magnification stretching through various studies on stretching means.

The thickness of the support film or sheet used in the present invention can be arbitrarily selected as required [2000, but usually 1 to 5000]
7+m, preferably 3-12 rHrm.

The method of providing the magnetic layer on the non-magnetic flexible support film or sheet of the magnetic recording article of the present invention is not particularly limited, but may include mixing a magnetic material with a binder mainly composed of organic polymer waste. There is a way to apply it. The magnetic material used is iron oxide (y-FetOs/Fe5Oa),
Iron oxides such as modified iron oxides, chromium oxide (C!rot) systems, iron-cobalt-nickel (or copper) by adding Co or adhering to CO or CO-containing Fθ, 04
It can be divided into alloys such as, and metal systems that use their surface change direction.

Another method is to directly form cobalt alloy on a support film or sheet by methods such as vacuum evaporation, svagitering, and ion plating without using an organic binder.
Any method can be applied, such as forming a phosphorus compound on a support film or an ID sheet by chemical plating. Furthermore, prior to providing the magnetic layer, the surface of the support film or sheet may be subjected to additional treatments such as cleaning, promotion of surface cleaning, improvement of smoothness, etc., or coating. Furthermore, 1-ting (back coating) for imparting slipperiness, abrasion resistance, anti-corrosion properties, etc. may also be optionally applied to the back surface of the support film or sheet (without a magnetic layer). I can do it. Next, the present invention will be further explained with reference to Examples.

In the examples, "part" represents a jusaki part. The intrinsic viscosity was measured at 35°C using orthochlorophenol as a solvent. Also, the 1IllI constant of the carboxyl group is A, CandH
method (Makro+r+a1.Ohθm,, 26
゜226 (195Fl)) was adopted. Furthermore, the hydroxyl groups were converted to carboxyl groups by reacting the polymer with succinic anhydride in α-methylnaphthalene, and measured by the method described above, and the difference between the carboxyl group value measured initially and the value after carboxylation treatment was taken as the hydroxyl group.

Examples 1 to 3 and Comparative Examples 1 to 3 Although the present examples show a method of capping the active end groups of a polymer with diphenyl carbonate, the present invention is not limited to this method.

19.4 parts of dimethyl terephthalate, 130 parts of ethylene glycol, 0.098 parts of manganese acetate tetrahydrate, and 0.079 parts of antimony dioxide were placed in a reactor equipped with a rectification column and stirred while gradually heating under a nitrogen atmosphere. .

The methanol produced as a result of the transesterification reaction is taken out of the system through a rectification column, and from the collected images, the transesterification rate is 98.
．． At 5% VC, the system temperature was 235°C. The rectification column was removed, the distillation condenser was removed, and the inside of the system (0.0395 parts of phosphoric acid as a C stabilizer and 1,03% of kaolin as a lubricant were added. The temperature inside the system was raised to 280°C. After continuing the reaction for 30 minutes, the pressure in the system was gradually reduced, and it took about 40 minutes to reach a high vacuum of less than 1 g.

The reaction was continued for 90 minutes. The intrinsic viscosity obtained from the sample at this time was 0.68. At this point, the system was returned to normal pressure with nitrogen and 7.5 parts of diphenyl carbonate (
3.5 molti per acid component) was added, stirred for 5 minutes, and O-5wn Ill? was added again, being careful not to foam. The following high vacuum was applied, the mixture was stirred for 15 minutes, and the polymer was taken out. The intrinsic viscosity of this polymer was 0.60. This polymer was formed into chips and dried for 7 hours using a hot air dryer at 150°C. This polymer was immediately melt-extruded using a film forming machine with an extruder set at a die temperature of 280° C., and the sheet was sealed onto a casting drum and taken off. The obtained unstretched sheet was sequentially biaxially stretched under the following conditions. , the stretching conditions were 3.9 times at 80°C in the longitudinal direction and 1 in the width direction.
The sea urchin axis-stretched film was stretched to 3.5 times its original size at 10°C and was then heat-treated at 200°C for a fixed length. The thickness of the obtained film was 12 microns, the transparency was good, and the intrinsic viscosity of this film was 0.52.The active end groups of this film were measured: 24 equivalents Jit/ton of hydroxyl groups, 37 equivalents Jit/ton of carboxyl groups. 't/ton. Similarly, various end-blocking samples were prepared, treated with diphenyl carbonate, and compared with normal polyester film VC'! The dimensional changes due to water absorption are shown below. Dimensional changes due to water absorption were measured by using a specimen with a sample length of 2 OC and a shoulder diameter that was dried in a dryer at 50°C for 16 hours.
By crushing the sample in water for 24 hours and measuring the change in length (change in length in the machine direction and/or width direction) before and after immersion. The degree of water absorption swelling can also be measured from the change in weight due to absorbed water. The former was expressed as water absorption expansion rate, and the latter was expressed as water absorption rate.

After corona treatment was performed on one side of the film obtained in Example 1.2, acicular r-type ferric oxide fine powder of 70 weight and urethane resin was added to the same treated side based on the total solid content. 15% by weight
, 10% by weight of Bo I7 ([vinyl chloride/vinyl acetate) resin], 5% by weight of thermoplastic polyester resin, 5μ thick
A magnetic tape was produced by laminating magnetic layers of 17 and 191 in width with a magnetic recording material using a conventional method. Adhesion, running properties, abrasion resistance of the magnetic layer, and distortion/disturbance during drop-out recording playback were at a good level.

Claims (1)

[Claims] A magnetic recording article comprising a squeezable support made of polyester and having a magnetic layer on one or both sides, wherein the polyester has an intrinsic viscosity of 0.4 or more; 1. A magnetic recording article characterized in that the combination of terminal hydroxyl groups and carhokyfur groups is 90 or less of the total amount of terminal groups and does not cause hydrophilic groups.