DE2130910C3 - Magnetic data carriers - Google Patents

Description

R »- O - C - O -

where mean:

a non-magnetizable substrate and at least one magnetizable layer which contains magnetizable particles dispersed in a binder and an ester lubricant,
Magnetic recording media, in particular magnetic tapes, generally consist of a non-magnetizable layer carrier to which a layer of magnetizable particles dispersed in a binder is applied, the binder often being a synthetic resin.

It is known that in magnetic recording, in particular when recording with, with the proviso that when R ¹ and R ^{J are} high information density, the magnetic heads are closely linear alkyl radicals, R ^{1 is} the remainder in contact with the magnetizable layer

CH ₃ - (CHj) _n and R ^{s must have} the remainder (CH ₂ ) ,,, CH ^a 5. Here appear phenomena that are related to the

mean, in which η and ρ such integer numbers are related to friction and the magnetizable

Change the layer to a greater or lesser extent. A frequently observed phenomenon is that material is torn loose from the magnetizable layer, which accumulates on the magnetic head or heads or is transferred to the surface of the magnetic tape, which can lead to a weakening or even disappearance of the recorded signal. These phenomena are particularly evident in the case of magnetic tapes which are used as memories in data processing systems and of such magnetic tapes which are intended for the recording of images, because of the relatively high relative speeds between the magnetic heads, in which R ^{3 contains} an aryl radical and q one an integer of 40 and the magnetic layer and that of this number of at least 9. Use occurring particularly high demands

3. Record carrier according to claim 2, furthermore. A particularly high load on the magnet is characterized by the fact that in the general bands occurs in certain systems for the recording formula R * means a phenyl radical. tion and playback of images in which the

4. Recording medium according to claim 1, that 45 track is scanned helically. Investments characterized by that in general of this type, often used for television broadcasts in Formula R »means an ethyl or phenyl radical in a closed circle and especially in school

5. The recording medium according to claim 1, since broadcasts are used, offer the possibility of characterized in that the magnetizable to produce a "fixed image". This will be Layer as carbonic acid ester, ethyl cetyl carbonate, 50 magnetic tape stopped, and the magnetic head continues Ethyllaurylcarbonat, Phenylcetylcarbonait or scanning in such a way that always the Contains didodecyl carbonate. same picture is reproduced. Under these conditions

6. The recording medium as claimed in claim 1, since a small area of the magnet is subject to this characterized in that the binding agent of the band is subject to high wear, the several tau-biagnetizable Layer of a partially equivalent to 55 send passages per minute, and the hydrolyzed vinyl chloride / vinyl acetate mixture leads when using an ordinary magnetic tape rapid deterioration of the layer with the disappearance of the recorded image.

It is known that the useful life of magnetic recording media, especially magnetic tapes, can be extended by
the magnetizable layer a lubricant such as
z. B. graphite or molybdenum disulfide incorporated.

R ^{1 is} an aryl or alkyl radical and R ^{2 is} an alkyl radical,

are that the sum of η and ρ is at least about 10, in an amount of about 1 to about 40 percent by weight, based on the weight of the binder.

2. Magnetic recording medium according to claim 1, characterized in that the magnetic Layer as an ester lubricant a carbonic acid ester of the general formula

R "- O - C - O - (CH ₂ X ₇ -CH ₃

polymer is made.

7. Recording medium according to claim 1, characterized in that the binder of the magnetizable layer made of a partially hydrolyzed, with a polyisocyanate crosslinked vinyl acetate / vinyl chloride copolymer.

8. Record carrier according to claim 1, da

characterized in that the magnetizable 65 These lead, however, in the amounts in which they

Layer, the carbonic acid ester can be used in a homogeneous mix without affecting the quality of the

Do not damage the mixture with the binding agent and the magnetized magnetic signal

contains particles. to the desired results. By using

which in French patent specification 1 032 730 be and ρ are such integers that the sum

.jwritten Silicones or those in the USA.patent- '' '■' ".-— * ~.: - -: -.

It is true that the high molecular weight hydrocarbon oils described in writing 3 144 352 are used as lubricants possible to improve the abrasion resistance in certain cases, but their effectiveness decreases from when the relative speed between magnetic head and magnetic tape is increased, especially when recording images, d USAPtthrif 3 27

of η and ρ is at least about 10, in an amount of about 1 to about 40 percent by weight based on the weight of the binder.

The term "aryl radical" given above is preferably a radical of the benzene or naphthalene series, which may be substituted.

The magnetic recording carrier of the invention, the one carbonic acid ester of the above

From the USA patent specification 3 274 1Π it is already ent known jo general formula in the specified amount, the fact that esters of fatty acids and monoalcohols hold shows a higher wear resistance fetch as a lubricant in magnetic recording media as magnetic recording media, which is one of the most popular in particular magnetic tapes for recording lubricants or a carbonic acid ester that tion of images, can be used. Do not use the general formula given above however, certain difficulties often arise, 15 included (cf. the two below with the exudation of the lubricant to game 6).

related. This phenomenon of switching off The magnetic recording medium of the invention is suitable

zens results from the fact that many are particularly good at recording common esters or used for making these esters images and for storing data in data Fatty acids mixtures from various processing plants as well as for sound recording, Nine homologues that are difficult to separate from one another and in which the magnetizable layer is very hard gene, for example of myristates, palmitates and conditions of use is subjected, such as. B. Stearates, stiffening, some of which during repeated runs in language teaching temperature liquid and others are solid and tren or, if high voltages occur, the former migrate to the surface 25 or if special profiles are used the latter favor, so that the formation of magnetic heads, as with perforated 16-mm or of solid deposits can be observed. Made of 35mm magnetic tapes.

USA.-Patent 3 492 235 it is also already The increased wear resistance of the magnet

knows, mixtures of hydrocarbons and recording media of the invention does not only affect Esters as lubricants in magnetic recording media - 30 their useful life, but also the re-gern to use. output quality in the case of recording j / on images

However, all of these known lubricants do not lead to the desired results, such as further below the following example. 6 show ...

The object of the invention is to provide a magnet 35
recording media, in particular a magnetic tape,
indicate that does not have the disadvantages described above and in particular a better one
Has abrasion resistance than the previously known magnetic recording media or magnetic tapes. 40 aliphatic and aromatic epochs, such as phenylcetyl

It has now been found that this task can be used, carbonate.

can be solved by containing as a lubricant according to a preferred embodiment

For the magnetic recording media, especially the magnetizable layer in the magnetic recording tapes, a certain group of carbon carriers of the invention are used as ester lubricants acid esters in a certain amount, 45 a carbonic acid ester of the general formula which gives the recording medium a higher wear resistance and thus a longer service life
to lend.

The invention relates to a magnetic recording medium, in particular a magnetic recording tape, the or that of a non-magnetizable layer support and at least one magnetizable Layer consists of magnetizable particles dispersed in a binder and an ester lubricant _.

tel, which is characterized, 55 denotes the radical R ¹ in the above-mentioned general that the magnetizable layer as ester lubricant formula I is an ethyl or phenyl radical, while

According to a further preferred embodiment, the sum of / 1 -r ρ in the general formula I given above is between about 10 and about 30, 60 where η = ρ and a number between about 5 and about 15 means.

According to a further preferred embodiment, the magnetizable layer contains the recording medium of the invention as the carbonic acid ester ethyl cetyl carbonate, ethyl lauryl carbonate, phenyl cetyl carbonate or didodecyl carbonate.

According to a further preferred embodiment, the binder consists of the magnetizable layer

or in the case of sound recording and the reliability of magnetic storage its use for data processing.

The magnetic recording medium of the invention can be used as a lubricant with particular advantage mixed carbonic acid esters, such as lauryl ethyl carbonate, cetyl ethyl carbonate, symmetrical aliphatic carbon acid esters, such as dodecyl carbonate, as well as mixed ones

Ri-OCO- (CH ₂ X-CH ₃ (If)

in which R ^{3 is} an aryl radical, e.g. B. a phenyl radical, which may be substituted, and q is an integer of at least 9.

According to a further preferred embodiment

tel a carbonic acid ester of the general formula

ri_O —C —O —R ²

(I)

where mean:

R ^{1 is} an aryl or alkyl radical and R ^{2 is} an alkyl radical,

with the proviso that when R ¹ and R ^{2 are} linear alkyl radicals, R ^{1 is} the radical CH, - (CH _ä ) _n and R ^{2 is} the radical (CH ₂ ) _P - CH ₃ , in which η

of the recording medium of the invention made from a partially hydrolyzed vinyl chloride vinyl acetate copolymer or from a partially hydiolysed vinyl acetate / vinyl chloride mixed polymer crosslinked with a polyisocyanate.

According to a further preferred embodiment, the magnetizable layer of the recording medium of the invention contains the carbonic acid ester in a homogeneous mixture with the binder and the magnetizable particles.

The carbonic acid esters which can be used in the magnetic recording medium of the invention can be prepared from known products , for example, by the method given below. This process consists in allowing an alkyl or aryl chloroformiai to act in the presence of a base such as pyridine on a saturated aliphatic alcohol which is branched, can be substituted by a halogen atom and can carry functional groups such as ether and ester groups . The ester obtained in this way is then purified by distillation.

The lubricant is used in amounts between about 1 and about 40 percent by weight based on the Weight of the binding agent, preferably of the order of magnitude of about 20 weight percent is used. The lubricant is in any Stage in the production of the magnetic layer is introduced into it. It can be seen from the collodion of the Binder, the paste formed by the magnetic substance and the solvent or the add the finished dispersion in the binder. You can also put the lubricant in the dry work in the magnetic layer after it has been applied to the substrate. d. h .. man can still work it into the already finished magnetic tape, and it is then advantageous to use the lubricant to be diluted by a compound that is not a solvent for the layer. making it possible is. incorporate it by brushing on or dusting.

The binders used are in particular vinyl acetate vinyl chloride copolymers, Vinylidene chloride and acrylonitrile copolymers. around copolymers of acrylic acidund'oder Methacrylic acid esters. around polyvinyl butyral, around butadiene styrene copolymers. around acrylonitrile, vinylidene chloride, malcic anhydride terpolymers, around optionally cross-linked mixed-pole condensates. like polyamides. Polyurethanes and Polyester, or mixtures of these binders. Particularly advantageous results are obtained, if you have a partially hydrolyzed and optionally crosslinked by isocyanate vinyl acetate / vinyl chloride copolymer or polyurethanes or mixtures of these binders are used, with the amount of binder, based on the magnetic oxide, between about 20 and about 40 "» the weight of the binder.

The magnetic recording medium of the invention may also contain other additives, such as oleic acid, or any other dispersing agents to facilitate the dispersion, conductive pigments, such as carbon, to avoid a static charge, or fillers, such as alumina or colloidal SiIiciumdioxyd, tnthalten, without thereby affecting the desired Properties are changed.

The magnetic substance is preferably acicular iron oxide; _{-Fe 1} O ₁ , It is pointed out that the lubricants used according to the invention are particularly advantageous if the length of the iron oxide particles is relatively short, for example between 0.3 and 0.4 μ, the magnetic layers against friction all the less are stable as the sizes of the crystals that make them up decrease. However, the invention can be applied to all magnetic recording media, in particular magnetic tapes, regardless of the shape and size of the crystals used, it being possible for the recording media to contain other magnetic substances, such as chromium oxide, ferrites or metal alloy particles, instead of iron oxide.

The magnetic layer can be applied to a wide variety of flexible substrates, for example on those made of cellulose triacetate, polyvinyl chloride or polyester, such as polyethylene glycol terephthalate. It can also be used to cover the surface of any other recording medium serve.

IZs should be pointed out: ··. · Ι. that the state of Surface of the magnetic recording medium of the invention is particularly smooth and that the abrasion of these Recording materials on the magnetic heads in relation to a magnetic substance that is not contains the lubricant used according to the invention, is significantly lower.

The following examples are intended to explain the invention in more detail.

example 1

In one with a thermometer, a stirrer and a three-necked flask fitted with a bromine ampoule were mixed with 242 »ceryl alcohol in 450 ml of toluene, the was distilled by heating to 35 C, dissolved. Then 90 g of pyridine (corresponding to a Excess of 12 mol percent) added, and in the mixture was mixed with the bromine bottle, 115 g of ethyl chloroformate (corresponding to an excess of K Molprozcnl) was added dropwise. The solution became cloudy due to the precipitation of pyridine hydrochloride, while the temperatures rose. The temperature was maintained during the introduction of ethyl chloroformate at 40 to 45 C while cooling with a cold water bath. Then the temperature was kept still ! 40 to 45 C for hour, cooled to ambient temperature and dissolved the pyridine hydrochloride in H) OmI water. The excess pyridine was by a 10 weight percent hydrochloric acid solution neutralized, washed with water, and the toluene solution was decanted off and dried. The toluene was removed by distillation, and by distillation under reduced pressure Pressure was cleaned the mixed carbonate that was formed according to the following equation:

C ₁₅ H ₁₁ CH OH - CICOOC ₂ H. - CH.N

_{-C 1} -H., CH ₁ OC- _{O-C 2} H.- '"CH.N • HCI

8 g of the ethyl cetyl carbonate produced in this way were incorporated into 1 k _{e of} a magnetic dispersion, the dry solids content of which was essentially 300 g of acicular iron oxide and 80 g of binder, consisting of 90% vinyl acetate / vinyl

to 1 Ο ^β / ο from a Buladiene / acrylonitrile copolymer, rebuilt.

It was homogenized and filtered, then the dispersion was applied to an ethylene glycol polylercphthalate support in such a way that a layer 8 to 1 micron thick (dry layer thickness) was formed. The dry layer . V ° _ .. i: _. U / oi-ri> n l-nlanHricrt. and

ulxr

Example 4

i-Poraellaneefäß, the 1 orze.long ^ ^

η e, n 1 g

J ¹ "linen, 50 g Jcs steel balls

_{d that by on} . _{3 mentioned} resin

placed. After the recording, an "image" was displayed. This continued for more than an hour without any change in the image while be. 's material containing no inventively ^ve ^ ^Nael "lubricant to the settlement, the picture changed and disappeared after a few seconds.

π η _SD j el 2 ao

, · M diameter

In a steel ball with a diameter of 8mm filled Porzellangefaß ίου * acicular magnetic iron oxide V * W "are mineral contacted with 140 ml of methyl isobutyl ketone and jg oleic acid. After 24 hours of dispersing, this paste was added by dissolving η of g of one to 77% by volume from vinyl chloride, to 20/0 from acrylonitrile and to 3 · /. from maleic anhydride based on the weight, existing mixed polymers obtained in methyl isobutyl ketone «KoI o_

dium added, i £ in the 6 g ^Lam f ^"ihyl ™ no * - were working. After the dispersion was 24stundigem H ^{01 "0} ^^ rcn. Ma used to make a gnetbandcs, as it is _the fchrieben ⁱⁿ .. ^In * P '. His life, oie such as m the example above indicated, determined wurd ^ oei B.

more than an hour while ^{u "ter} _Q ^ _r ^e: ™ _d ⁿ J of the comparative product ohn ^ Kphlensaureejwfler attempt after a few minutes had to be canceled ^.

sä?

give.

Methyl isobutyl alcohol 100 ^m

_lo ^y _hexanone 20 ml

^ 5 g

Soluble polyurethane resin 15 g

_Didodecyl carbonate 7.5 g

The didodecyl carbonate was made by reacting phosgene or lauryl chloroformate with lau- ^ _{h estelh} .

_{2 /, stündigern} homogenizing were _a p _o | added yisocyanats that at ^ 4 ^ obtained _from 3 molecules of toluene diisocyanate j _Molecule, trimethylolpropane ^ Production of magnetic tape, as described ^ _{, the Iron oxide was

- £ _{n used} . _The magnetic tape was some P _{so that} ^ _{Vernetzungsrca} ction located

_Could ^ta ^ _Taen ^ß _{di 's. The} crosslinking can be controlled by the temperature and / or by adding a Kataly _{satorS) wic z} . _B. of a tertiary amine, at the time _{of coating the} support at the time

Oxide suspension can be accelerated.

υ y ^, ρ ^^ _{magnetic tape was used}

Conditions tested as in the previous examples. The same track could be _scanned more ν ^^ without

a _{change in the} image occurred.

Example 3

M three-necked flask containing 300 ml of toluene I man 121 g of cetyl alcohol while warming to 35-! C Sh 4- D ^ J-rf- ^ ii 80 g of pyridra and 82 g of phenyl chloride were added dropwise. The temperature was about 4 held at 40 ° C. The excess was removed by a few drops of AthylaiK.

and the reaction product was dissolved in 200 ml of destiii poured water, in which it is formed

dissolved hydrochloride. The «» «^ '' SSsed Was neutralized with hydrochloric acid

Toluene solution was mixed with water. Back toluene was removed by distillation. "Jeremiah stood was in ethyl alcohol" ^{mk "sta} _c ^ _at obtaining the mixed Cetylphenylcarbonat ^

8 g of this compound were added to an iv the ^{ν partially hydrolyzed by Α »^ ™ 3 £ * J. ΐη} £ ^οι "° ™ copolymer in Methyl.sobutylket had been. This collodion was ι mixed, which by Di
shaped cm / -Fe ₂ O _-1 in 140
5 g of oleic acid in a 1-1-f

had been. . due to

As in the ^ν0 ™ ^ _ft>

play, made a magnetic tape and g P

Example 5

150 g of acicular magnetic iron oxide Fe ₂ O ₃ and a solution obtained by dissolving 15 g of a partially hydrolyzed vinyl chloride / ¹ »mylacetate copolymer in 200 ml of methyl isobutyl ketone were introduced into a porcelain vessel containing 2 kg of steel balls with an average diameter of 81%. After " ⁷ ^

digem dispersing a 20 g of the ti

hydrolyzed vinyl chloride / vinyl acetate copolymer, 120 ml of methyl isobutyl ketone and 7 g of didecyl carbonate-containing solution were added. To The oxide suspension thus obtained was honed for 24 hours, as described in Example 1 used to make a magnetic tape. Since: tape was tested as in Example 1, and the au BHId recorded on the tape changed after no more than an hour's use while there is picture on a comparison tape that doesn't have coals acid ester, ver

«; produced with νΕΐ> »ι.ιι ^ ϋ .. _& of dioctyl carbonate instead of didecyl carbonate a corresponding improvement in terms of wear resistance was achieved.

409 638/31

Example 6

(Comparative example)

That the improvement achieved by the present invention in terms of a higher wear resistance of a magnetic tape was not predictable, show the following experiments.

Attempt a

8 g of di (2-ethylhexyl) azelate were introduced into 1 kg of a magnetic dispersion, from which a Magnetic tape was produced which was tested as in Example 1 on a magnetoscope. Already after In a few minutes, the image recorded on the magnetic tape disappeared and on the pickup head Abrasive material accumulated from the magnetic tape in a significant amount.

Attempt B

When in the above experiment A the di (2-ethylhexyl) azclate was replaced by 8 g of silicone oil, showed There was also no improvement in the test of the magnetic tape produced therefrom on a magnetoscope with respect to the abrasion resistance of the magnetic tape compared with a comparative tape containing no lubricant.

Attempt C

When using 8 g didecyl oxalate instead of the di (2-ethylhexyl) azclate used in experiment A When the magnetic tape made therefrom was tested on a magnetoscope, it was found that it was recorded The image disappeared after a few minutes.

Attempt D

When using 8 g of dibutyl carbonate instead of the di (2-ethylhexyl) azclate used in Experiment A In the test of the magnetic tape produced therefrom, as in test A, there was no improvement with regard to the abrasion resistance of the magnetic tape compared to a comparison tape, which did not contain this carbonic acid ester.

The above experiments show that when using the known lubricants (silicone oil,

ao organic acid ester) and even when using a carbonic acid ester outside of the claimed Group as SchmiennitUel in a magnetic data carrier no improvement in the abrasion resistance of the magnetic recording medium

»5 without impairing the recording properties the magnetizable layer compared to a comparative material containing no lubricant could be obtained.

Claims (1)

Patent claims: I. Magnetic recording media, in particular magnetic recording tape, consisting of a non-magnetizable layer support and at least one magnetizable layer in one BinderaitteJ dispersed, magnetizable particles and an ester lubricant contains d 9. Recording medium according to claim 1, characterized in that the sum of η + ρ is between about 10 and about 30 in the general formula. The invention relates to a wear-resistant Ma- pg, magnetizable part of the magnetic recording medium, especially a wear-resistant part as well as an ester lubricant that contains solid magnetic recording tape made up of duh kih iib Shihä d i characterized in that the magnetizable Layer as an ester lubricant a carbonic acid ester of the general formula