JPS60182016A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a tape having simple constitution and ultra-high performance by having a magnetic layer contg. a polyurethane resin having specific % or above of breaking extension on one surface of a base and forming the other surface to specific mum average surface roughness without having an auxiliary layer. CONSTITUTION:The polyurethane resin having >=900% breaking extension to be incorporated into a magnetic layer is a polyurethane resin having <=200kg/cm<2> breaking strength. More specifically, the soft polyurethane incorporated therein has an effect of buffering the winding pressure against the transfer of the magnetic layer to the rear surface so as to decrease the chance for transfer when the tape is held in the winding style under specified winding pressure. Even if the adhesion to the rear surface which is the preliminary stage for tentative transfer arises, said polyurethane returns the adhered part to the magnetic layer side in the stage of unwinding. The average surface roughness Ra of the base surface is 0.015-0.025mum. If Ra is >0.025mum Ra, a sharp decrease in an SN ratio arises from the large tendency to transfer and if <0.015mum Ra, a sharp deterioration in the jitter characteristic is resulted from poor running stability. The dispersibility of the magnetic powder in the magnetic layer is improved and the mechanical strength is increased if a cellulosic resin and vinyl chloride copolymer are also incorporated into the binder in addition to polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic recording medium. ) It has excellent surface properties, orientation, durability, abrasion resistance, and magnetic output, making it suitable for R media.

(Prior art) Magnetic Mi recording media usually include magnetic powder and the powder as a base material.
1. A magnetic paint containing a binding binder component is coated on a non-magnetic support such as a polyester film and dried to form a film. /'l.

This magnetic recording medium is 6% g to 1C or kL.
I/1-Fn, +/AJ'-1++1J1 (48*b4
nkItr+L';4+'tl,sX? J--A=A
・h-J> is done. Therefore, the binder component used has excellent dispersibility of the magnetic powder, and is suitable for magnetic recording media.
C. Provides excellent electrical characteristics such as high sensitivity and high S/N ratio.
In addition to k/'J, it is safe to use one that improves the abrasion resistance and heat resistance of the magnetic layer to improve the durability of the magnetic recording medium.

In this way, the binder component "t" plays an extremely important role in terms of the characteristics of the magnetic recording medium.

A large number of thermoplastic resins or thermosetting resins are used as the polymer used as the binder, and in particular, vinyl chloride-vinyl acetate resin, cellulose conductor, epoxy (d resin, polyamide resin In1, etc.) are used as the binder. and γ1L series of polyurethane resins are used.

+fjJ abrasive polyurethane is used for 9f]1
It has strong adhesion to other substances, is mechanically strong and can withstand stress or bending applied by reaction, and has good abrasion resistance and weather resistance.

However, when using a mixture of the above-mentioned fats,
HMI ■1 A old melting set, -, +1 Magnetic h et r to ηri Shutsu old 4 Te! No. 1-?
-Magnetic recording media still lack sufficient performance in terms of wear resistance, flexibility, surface properties, etc.

Recently, with the development of magnetic recording method, for video, city; 3
Magnetic recording media (hereinafter referred to as tape) for use in the Q-4 Ikukawa, Meteor, etc. are now required to have tape performance of 6 and 7 mm. F6, etc., where the relative speed of the tape is high, requires particularly high steel durability and stable running. te℃・ro. Because of this, the durability of the tape itself is 1. Of course, it is extremely important to protect the tape from scratches during running, and to ensure that it has a sufficient cleaning effect on the head. It is a costume.

Until now, the friction of the magnetic layer has been reduced by one blow,
4+1 (each, Ti1d IF, (agents (e.g., silicone oil, graphite, nonoponbrasograft polymer, -Senkaji Rinten, binarized tungsten,
Lauric acid, myristic muta, carbon atoms 12 to I (i
(IJy, fatty acid ester from 11 alcohols with a carbon number of 21 to 231 bjl) I don't know what to do. .

However, even with the addition of these lubricants, it is still not possible to obtain sufficient adhesion properties, and it is necessary to prevent undesirable deformation such as pluming.

I can't.

In addition to the aforementioned fatty acids and fatty esters, abrasives such as alumina, corundum, artificial diamond, garnet, etc. may also be added. [The layer phase used is one with an average particle diameter of 0.05 to 0.5μ, and the surface 3V roughness of the magnetic layer is 003μrn or more.
Ill do it.

Also, due to the death of the polishing phase, methyl life is controlled by Kino 1. Therefore, considering this, the total amount of fatty acids and fatty acid esters, especially (ilt! The phase is changed to magnetic powder 1)
2 to 8 City & Ji%, and corresponds to il, C above Aiko 1 upper (na (丑ffJ>に文, lj, 0.7 to 23 small it,
It is known that the methyl life can be lengthened by setting ν to %.

Moreover, it is desirable to reduce this total range ((17 to 3 M%) of the magnetic layer, etc. by 1°) and maintain a high luminous S/'N ratio.

In history, Hifuo tape was even more 'di' than commercial performance tape.
In super-heavy performance tapes with excellent WN conversion properties, the back coat layer (BC layer) is essential for improving running stability, bite, and 44-year stability. There is.

In the BC layered tape, the magnetic field of the support is lj
4 It is set up to confront the person who has it.

If: JL-Magnetic powder, such as carbon black, silicon oxide, titanium oxide, aluminum oxide, etc., preferably carbon black or titanium oxide, is added to the BC layer, these non-magnetic powders are added to the BC layer. By making the surface rougher, the surface of the BC layer can be appropriately roughened (matted) and its surface properties can be improved. Furthermore, when carbon black is used in combination with other non-magnetic powders, the effects of both improving surface properties (stabilizing runnability) and improving conductivity can be obtained.

The surface roughness of the BC layer is semi-uniform roughness of the center line of the surface unevenness.
We believe that it is best to set the roughness (Ra) to 0.01 to 0.1 μIn and the maximum roughness (Rmax) to 0.20 to 0.80 μm. [(a) If the Rld-RmnxO value is too small, the running stability and the winding appearance at the same time as tape winding will be unstable; if it is too large, transfer from the BC layer to the magnetic layer (at the same time as tape winding) will occur, causing the surface to become There is a flaw in history.

In addition, the blooming and slipperiness of the BC layer are improved by adding the same fatty acids and fats and esters as in the U-f and jfi layers to the BC layer.

As mentioned above, the performance of the "C tape" has greatly improved due to various performance improvement measures for the magnetic layer and the addition of a BC layer, but when deterioration over time is taken into consideration, stickiness due to the BC layer, transfer of adhesion to the magnetic layer, and scratches can be expected. etc. are unavoidable, and if there can be a restriction on the winding length corresponding to the thickness, a tape with super high performance without a BC layer is desired.

Furthermore, if there are fewer layers, not only will it be advantageous in terms of manufacturing costs, but the structure of the magnetic recording medium will be simpler, which will improve the reliability of the medium and expect less deterioration over time. be done.

(Objective of the Invention) The object of the present invention is to provide (111#) a tape that is simple in structure and has super high performance;
2) To provide a tape with less performance deterioration and less occurrence of defects over time, and (3) To provide a tape with excellent video characteristics.

(Structure of the Invention) The present invention of Komei has a magnetic layer containing a polyurethane resin with an elongation at break of 9 uo% on one side of a support, and an auxiliary layer on the other side. The next surface average roughness of the force surface is 0.015 to 0. (125 μm can also be achieved with tape.

According to an aspect of the present invention, the fracture elongation 9 in which the magnetic layer contains
00% or more polyurethane 4V (the resin has a tensile strength of 200K)
It is preferable to use a polyurethane resin (hereinafter referred to as soft polyurethane) having a polyurethane resin having a polyurethane resin (hereinafter referred to as "soft polyurethane") having a polyurethane resin having a polyurethane content of less than g/CTfL (hereinafter referred to as soft polyurethane). It has a spinal pressure buffering effect against the adhesion to the open surface, reducing the chance of adhesion, and adhesion to the front surface, which is before temporary adhesion, occurs and C is also removed when unwinding. Return the corroded portion to the magnetic layer side.

In addition, the elongation at break is 9, which has good miscibility with soft polyurethane.
less than 00%, tensile strength greater than 200 kq/art;
1ζ urethane (fat (hereinafter referred to as hard/urethane)
It is preferable to use them together.

In the embodiment of the present invention, in order to effectively exhibit the characteristics of soft polyurethane, it is extremely important to specify the mechanical properties of polyurethane σ) within the above range. . In order to fully produce the above-mentioned effect of the soft J urethane, its tensile strength and elongation at break were lowered by 200 kg/d, respectively, and 9 Q (1
% or more, preferably the tensile strength is 2110 ky
By using a hard polyurethane in combination with a VC of more than 1 cnl and an elongation at break of less than 900%, it is possible to suppress the adhesion of the tape magnetic layer. As a result, the tape's abrasion resistance, durability and 80-layer non-supporting surface while reducing tackiness? ] Due to the surface properties, the supercrystalline fJ-1 stops 7! You can roll the tape. 1 Figure 1 shows the tensile strength 2 (l
tJ k7 /cm The relationship between the elongation rate (elongation at break) of soft polyurethane and the adhesion resistance of the magnetic layer is shown, and it is found that when the elongation rate is increased to 900% or more, the properties are significantly improved. Ru.

With this invention i! The preferable range of the physical properties of both of the polyurethanes used in 12 is tensile strength I for soft polyurethane.
~100k! lII/(XrL, elongation at break 9 (10~
1200%, and the hard IJt polyurethane that may be used in combination has a tensile strength of 3po0~ti tl Okg/'']rr
1-piece breakage O: 4 (01 to 750%).

Mechanical properties of polyurethane related to wood (
Figure 1-1 shows iM as elongation rate (a) and weight (a) in Figure 2.
In the graph of bl, lJ++W (load 7Jr 211
(lkf17cniOhi) and aI&! (1 shell rate 9
00%) and a (90(1%.

b>20 (Hard yr: II urethane in area B1 of JkgΔ (7, on the other hand a, j 9tlt1%, b;
,',, VC means that the soft polyurethane belongs to the region A1 of 200 kg/Cm. Furthermore, the preferred i ratio ranges are shown for antacids A2 and B, respectively.

In addition, in this defense, the mechanical properties (+[1', (tensile strength, elongation at break)) of the polyurethane described in 2. It is equivalent to A, Y's 5 pieces, 1 ino [elongation is the elongation when cutting 1 time, ill, road] and C.

In addition, as an unfavorable evil, it is preferable to have immature non-repairable particles such as carbon flanks on the magnetic layer to suppress transfer to the surface. It's so good.

In particular, carbon blanks can provide properties such as s7M, properties, and light-shielding properties in addition to the above-mentioned effects, so a suitable carbon blank is selected or assembled according to the struture index. A material having a high structuring index (σ) has a large specific surface area measured by the BET method, so it is suitable for providing conductivity, and a material having a relatively low intex is suitable for shading.

Generally, when a tape is in use, air is accumulated and discharge occurs between the tape and the magnetic head, generating C noise (which easily attracts dirt, etc.) and causing dropouts. There is. For video use, a method of adjusting the magnetic layer while the tape is running is known, by detecting the difference in Y-transmittance between the third tape part and the leader tape part. . For these reasons, magnetic 1/1
It is required that the surface electrical resistance of the layer be less than 1 (JIIΩCnL) and the light transmittance of the tape portion where the magnetic layer is 0.05% or less. Carphone Noranoku’s ratio between 4j″
1 is 20il ~Fi Ofl ni/I, A'A
r-photosensitive carbon branocle (one is 40~2 (l)
o nlVg2, i.e., the ratio (if the surface phase is less than 2oom'/&, the diameter is large enough to cool the carbon black), and the property is opaque. If the particle size exceeds 5 (lOnlVg), the particle size becomes too small and the dispersibility of the carphone blank tends to deteriorate.

The specific surface area is 40 tn/j! If it is too thick, the particle size will be too thick and the light-shielding properties will be poor (there is no need to worry about increasing the cooling bI more than necessary, and it will be 200+++/g).
If it is more than that, the particle size tends to be small and the dispersibility in the layer tends to be poor.

There is a certain preferable range for the mixing ratio of each of the above carbon blanks (grainy carbon black/light-shielding carbon blank) (N amount ratio), from 90/10 to ~60/41J is even better. If this mixing ratio is thicker than 90/10, the proportion of conductive carbon black will increase, so the light-shielding property will become opaque, and if it is smaller than 5t1150, there will be less conductive carbon blank, resulting in an increase in surface resistivity. Please note that the above 13ET method (Brunauer-Emme
tt-Teller method), first,
Carbon blank powder is heat-treated at around 250°C for 30 to 0 minutes while degassing to remove what is adsorbed to the powder. The pressure was set to 0,5kyγ/rrr'', and adsorption measurements were carried out using a 7J element at a liquid temperature (-195°C) (i night 1. < is J).

Ame, Chem, Soc, 60:109
(1938)).

Next is the personality layer? The surface average 4ji Ra of the bare surface of the support according to the present invention facing the coated support surface is Qil 15 ~
0.025μm, but at R8 Ra) 0.0
When it is 25 μm, the S/N ratio increases by +1 and the S/N ratio suddenly decreases, and when Ra (0,0) is 511 m, the running speed is
, the sex is sad and jittery and rapidly deteriorates. 4i above
'l'ilf is shown in Figure 3.

Support surface Q (month) 25μm/''Ra, '120
．． 01511m, uniform 111 Ra, no appearance 2. Nini Y! Samurai Kaisho 5:3-1 (No. 16783, same E
It may be possible to follow a known method such as No. +3-125479, No. 54-34207, or Japanese Patent Publication No. 5F'1-19263.

Note that the surface of the support may be subjected to auxiliary processing such as antistatic processing to the extent that the surface roughness Ra is not impaired.

The average surface roughness Ra is a numerical value in μm of the average deviation of the surface with respect to the center line of the surface roughness curve obtained by the stylus method.

As a binder, in addition to polyurethane, the dispersibility of the magnetic powder in the magnetic layer will be improved if a cellulose-based (☆) fat and reinforced vinyl-based copolymer is also incorporated. target strength increases.

For 1φ use, cellulose ethers such as methyl cellulose, and nitrocellulose are used as fiber resins.

cellulose inorganic acid esters, cellulose organic acid esters such as a7tyl heptylulose, etc. can be used.

Nitrocellulose is preferable among the cellulose resins of cholera7.
Examples include copolymers containing vinyl acetate.

In addition, regarding the entire binder composition, the ratio of the above-mentioned polyurethane and other trees 1jm (total amount of cellulose resin and cyclized vinyl co-bond base) is 21t tt.
It has been confirmed that the i ratio is preferably 90/10-50/5 (1, <,) i5/15-60/40 is more desirable. Outside this range,
If there is too much polyurethane, poor dispersion tends to occur, which is still 9! If the content of other resins increases, the surface properties tend to deteriorate, and the still properties tend to deteriorate, and especially when the content exceeds 60%, the film resistance tends to deteriorate overall. It becomes undesirable. .

The soft polyurethane and hard polyurethane used in the VC of the present invention include phthalic β, aphthalic acid, dibasic dibasic acid such as dibasic 11-ruic acid, maleic acid, ethylene glycol, glohylene glycol, butylene glycol. , diethylene glycol, etc.
A Mol <&M1 Contains polyalcoholic compounds such as rimedalol noropane, hexane trimer, glycerin, trimenalol glopane, heggin trichloride, glycerin, trimethylolethane, beet/taeri, noritol, etc. Polyester polyol synthesized by reaction with any two polyols selected from 716 glycols and polyols; , ε-methyl-ε-caprolactam, γ-
Lactone-based polyesters synthesized from lactams such as butyrolactam; or polyols such as halopolyneedle polyol synthesized from ethylene chloride, glohylene megizide, ethylene oxide, etc. , 4.4'-diphenylmethane diisocyanate, hecamethylene diisocyanate, metaosilylene diisocyanate, and other diisonite compounds urethanized polyene delpholiurethane resin and polyurethane polyurethane 4 months a. f1 le.

Urethane Tsukuda 11iT N according to the present invention is mainly produced by the reaction of polyisocyanate and polyol,
Regularly manufactured ζ1+, and C free inanate and (
or) Hydroxyl-containing, ri-containing zurotsu
It may be in the form of a urethane preformer or one that does not contain reactive end groups, such as a urethane elastomer.

Since urethane 4HIlv, urethane polymer, urethane elastomer manufacturing method, curing and crosslinking method, etc. are well known in the art, details of the length will be omitted.

The ferromagnetic powder used in the magnetic layer according to the present invention is γ-F'e203, CO-containing-
Iron oxide magnetic powder such as Fe203, Feso4, CO-containing F"e304; Fe, Ni, C01Fe-Ni-C
o alloy, Fe-Mn-Zn'a elephant, Fe-Ni-Zn
Alloy, Fe-Co-Ni-Cr alloy, Fe-Co
-Ni-P alloy, Co-Ni alloy, etc. Fe, Ni, c
Various ferromagnetic powders such as metal magnetic powders whose main ingredients are o@ are available.

As a binder for this magnetic layer, in addition to the above-mentioned binder, this binder and a thermal resin or a thermosetting resin may be used.
, reaction type (91 resin, 'II (, tIC) is also used, and a mixture with coronal beam irradiation hardening type resin is used. As a thermal ij J plastic resin, the softening temperature is 150℃ or higher. lU, 1) 00-200.(100, degree of polymerization is about 200
~2.0 (+013H degree), such as acrylic acid ester-acrylonitrile co-jE combination, single-component vinylidene-acrylonitrile co-polymerization, holamide Tsukuda, styrene-phtadiene co-polymer itself, polynisdel 4MJ Jl
A mixture of synthetic rubber such as KR, amino resin, and synthetic rubber of each a+ is used.

Thermosetting value As a greasy or reactive resin, the molecular weight is below 2tJO,0 (IOJ2) in the form of a 5-liquid coating, and after coating and drying, it is difficult to react such as condensation and addition. The molecular weight becomes infinite.Also, among these trees B'bf, those which do not soften or melt during the time period (a) when 11M is thermally decomposed are the best. Specifically, examples include phenol resin, urea resin, silicone resin, acrylic resin, urea forno-aldehyde, polyamine resin, and mixtures thereof.

Examples of the γ6 radiation curable resin include unsaturated prepolymers such as urethane acrylic type, polyamide acrylic type, etc., and polyfunctional monomers such as urethane acrylic type and hydrocarbon type.
Ru.

The mixing ratio of the ferromagnetic powder and the binder according to the present invention is 5 to 5 parts of the C binder to 100 ηI parts of the ferromagnetic powder.
40 (l 791 parts, preferably <t110 to 200 parts by weight). If the binder is too large, the recording density of the tape will decrease, and if it is too small, the strength of the magnetic layer will be poor, resulting in poor durability. Lights such as decrease in quality, falling powder, etc. (7
An unexpected situation occurs.

Furthermore, in order to improve the durability of the tape of the present invention, <a
In addition to the isocyanates mentioned above, triphenylmethanetriynnyanate, tris-(p-ynynatophenyl)thiophosphite, and polymethylenepolyphenylincyanate may be used as crosslinking agents in the transparent layer.

The paint used for VC to form the above-mentioned magnetic layer paint may contain additives such as a dispersant and an antistatic agent, if necessary.

Dispersed AIJ Toshiko & i used, powder dust, phosphoric acid ester, amine compound, alkyl sulfate, fatty acid amide, higher alcohol, polyethylene oxide,
Examples include sulfosuccinic acid, sulfosuccinic acid esters, surfactants of electricity 1, and salts thereof, and salts of polymer dispersants having a negative group (for example, -COOHl-PO3H) can also be used. This i7. Dispersant r/i1'
44i may be used alone, or C may be used in combination with two or more citrons. These dispersants are added in an amount of 1=2 U parts by weight per 100 parts of binder. These dispersants may be used to pre-treat the magnetic powder in advance.

The anti-stick agents that may be used include carbon black, graphite, tin oxide-antimony oxide yarn compounds, titanium oxide-tin oxide-antimony oxide yarn compounds, and other conductive agents. Powder; present ho = :y fl
Natural surfactants; nonionic surfactants such as alkylene oxide, glycerin, and grindol;
Higher alkylamines, 2744 M ammonium salts, hyridine, other complex g < bt, phosphonium or sulfonium compounds, thionic surfactants; carbonic acid, sulfonic acid', mW, (IliC acid ester group, phosphoric acid Nisder group) Examples include anionic surfactants containing acidic groups such as; amphoteric surfactants such as amino acids, aminosulfonic acids, healthy acids or phosphoric acid esters of amino alcohols, and the like.

Fatty acid esters that can be used as the lubricant according to the present invention include butyl caproate, butyl caprylate, butyl myristate, butyl laurate, ethyl palmitate, butyl palmitate, ethyl behenolyte, phthyl behenate,
Examples thereof include phthoxyethyl behenate, proyl stearate, butyl stearate, and stearate, but those having 16 or more carbon atoms (eg, butyl stearate, proyl stearate) are preferred. In addition to these esters, other fatty acid esters may be used in combination.

Furthermore, fatty acids that can be used with the fatty acid ester are:
Examples include myristic acid, palmitic acid, behenic acid, etc., but the number of carbon atoms is not particularly limited. These I
In addition to +h fatty acids, other fatty acids may be added to the mixture.

In addition to the above fatty acids and fatty acid esters, the magnetic layer of the tape according to the present invention contains abrasive materials such as alumina, silicon carbide, acid-specific chromium, corundum, artificial corundum, diamond, artificial diamond, garnet, Emery (products: corundum, magnetic steel, etc.) is added.
'U good. The research phase of Kosai et al. has an average particle size of 0.05~
A size of 0.05 .mu.m is used, and a particularly preferred size is 0.1 to 2 .mu.m. These abrasives are used in an amount of ~9 parts by weight based on a small amount of Nt magnetic powder JOO. In this case, the total amount of fatty acids and fatty acid esters in the upper part of the magnetic powder Tli () θ is 0.2 to 20
It was found that it is desirable to have a heavy needle portion, and that there is a correlation between this sum and the addition loss of the abrasive.

That is, since the methyl life is controlled by the structure of the magnetic layer I, the combination Fi1i of fatty acid and fatty acid ester can be optimally determined by taking this into account. When the amount of abrasive material is 2 to 8% by weight based on the magnetic powder,
The methyl life can be extended by setting the total amount of the magnetic powder to 0.7 to 1% to 3% of the magnetic powder.

Moreover, this total amount range (0.7 to 3 double vibrations Oio) is desirable in terms of reducing powder fall-off of the magnetic layer, etc., and maintaining a high lumi-SZN ratio.

In the present invention, the solvent for the magnetic paint or the solvent used when applying the magnetic paint includes ketones such as acetone, methyl ethyl ketone, methyl isopnal ketone, and cyclohexanone; alcohols such as methanol, ethanol, propanol, and phthanol; Esters such as eIF-acid methyl, ethyl acetate, butyl acetate, ethyl lactate, ethylene glycol heptanoacetate, etc.: ethylene glycol dimethyl ether, diethylene glycol monoethyl needle,
Ethers such as dioxane and detrahydrofuran; aromatic hydrocarbons such as benzene, toluene, and nitrogen; halogenated hydrocarbons such as methylene chloride, ethylene chloride, VM, cyclized carbon, chloroform, and dichlorbear-4'7 etc. can be used.

In addition, examples of the support material on which the magnetic layer is to be formed include polynisdelics such as polyethylene terreclate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose tiacetate, Glass materials such as polycarbonate, residual materials such as Al, and Zn are used.

The Jν diameter of the kneaded support is approximately 3 to 100 μm in the case of a film or sorted form, approximately 5 to 50 μm in ID, and 30 μm to 10 mrl in the case of a disk or card.
V, AI is current.

Magnetic powder and the above-mentioned binder, dispersant, 4X1 detergent, (
The antistatic agent, solvent, etc. in the TLT abrasive layer are mixed to form a magnetic paint.

When it comes to crosstalk, the magnetic powder and each of the above-mentioned components are added either all at the same time or individually one after another in a crossfire-like manner. For example, first, magnetic powder is added to a solution containing a dispersant.
There is a method of mixing the mixture for a certain period of time, and then adding the remaining components and continuing the mixing to form a magnetic paint.

When distributing crosstalk, mix kF of each a! machine is used.

For example, two roll mill, three roll mill, ball mill,
Pebble mill, sand glider-1Szegvari attritor, high speed impeller disperser, cylinder speed stone mill,
These include an Akane speed 1g1i percussion mill, a Disper Kneader-1 high speed mixer, a homogenizer, and an ultrasonic dispersion machine.

Technology related to crosstalk dispersion includes 'l', C, PATTON
Station Pa1nt Flow and Pigme+f?
Dispersion (1964) John W.
published by Illey & 5ons).

Also, U.S. Patent No. 2', 581,414, 2.85Fi
, also stated in No. 156.

Apply the magnetic paint onto the support (Ij L), and form the magnetic layer (C).
As an application method for drying, air doctor coat)
, frede coat, air knife coat, Swiss coat, impregnated coat, reverse roll coat, transfer roll coat, clayer coat, kiss coat, cast coat, tin lay coat, etc., and other methods are also possible, and these specific methods are available. It is described in detail in ``1 Coating Engineering'' published by BAr/'i Asakura 1 Store, pages 253 to 277 (published on the following day in March 1971).

By such a method, the magnetic layer coated on the support is optionally treated to orient the magnetic powder in the layer, and then the formed magnetic layer is dried. Further, if necessary, the tape of the present invention is manufactured by subjecting it to a smoothing process as shown in Table 1 and cutting it into a desired shape.

In this case, the orientation magnetic field is approximately 500 to 20
The drying temperature is about 100° C. to about 100° C., and the drying time is about 3 to 10 minutes.

The orientation method of magnetic powder is also mentioned in the following text.
There is.

For example, U.S. Clock No. 1,949,840, 2°796
．． No. 359, 3. (No. 101,891, No. 3,172
No. 776, No. 3,416,949, No. 3,473.
! lli.

No. 3,681.138, /Koakiaki: 3z-342
7+3, 39-28368, 40-2: U624
No. 40-23 fi No. 25, No. 41-13181
No. 41 (-131143, No. 48-39722, etc.).

The orientation direction of the magnetic material is determined by its intended use. That is, in the case of audio tapes, small video tapes, and memory tapes, it is parallel to the length direction of the tape, and in the case of broadcast video tapes, KiI: is 30 to 9 in the length direction.
It is arranged with an inclination of 0°.

(Example) The present invention will be explained in more detail below using examples.

It will be readily understood by those skilled in the art that the ingredients, proportions, order of operations, etc. herein may be modified without departing from the spirit of the invention.

Example 1 First, a magnetic paint having the above formulation was prepared.

(1011rel() Co-containing -Fe, 0310 (1 Soft polyurethane (elongation rate 910%, tensile strength 125 to 9/7) (Paccel EA 234 manufactured by Daicel Corporation)
) 10 Nitrocellulose () 01 synthetic cell line)
10 Isocyanite 5.4 Myridic acid 0.5 Palmitic acid 0.5 Alumina 3 Menal ethyl ketone 70 Toluene 30 Cyclohegizanone: 30 Carphone black (Contactex 975) 5 Thoroughly stir and mix this composition in a ball mill. 1, further polyfunctional isocyanate (Coronate L manufactured by Nippon Polyurethane Co., Ltd.)
After adding 5 parts of, the mixture was filtered through a filter with an average pore size of 1 μm. The obtained magnetic paint was applied to the surface of a polyethylene terephthalate base having a thickness of 14/Am and an average surface roughness (Ra) of 0.020 μm on the g side to a dry thickness of 4 μm.

Thereafter, the magnetic layer was processed using a super-press roll to obtain a wide m-type film with a magnetic layer of JJl thickness τ\. This film is 1 inch 1
The sample was cut into 161 pieces to prepare video tape sample 1.

Example 2 Soft polyurethane pack in the above implementation +9111
IF, instead of A234, use soft polyurethane T-5260 (
Elongation 900'%, tensile strength l (+Ok7/r, ff
Sample 2 was obtained in exactly the same manner using 1) (manufactured by Dainippon Ink).

Example: 3 In the same spirit as Example 2, MAv was applied to soft polyurethane.
-2o+o (elongation rate 1175%, tensile strength 30ky/c
At ) (manufactured by Inuhishaya Kakogyo), Sample 3 was obtained.

Comparative Example 1 In the magnetic paint formulation of Example 1, soft polyurethane P
accel u a 234 hard polyurethane gst
ane5702 (BFGoodrich Compa
ny ) (elongation rate 625%, tensile strength 246 kg/
rytt) and the average roughness Ra) of the back surface is 0.
．． Comparative sample 1 was obtained using a support having a diameter of 0.008 μm.

Comparative Example 2 The support in Comparative Example 1 had an average surface roughness Ra) of 0.
Comparative sample 2 was obtained with a good surface area of 0.031 μm.

1) 1 [Runability, tackiness, gloss, and chroma S/N for Sample 1.2.3 and Comparative Sample 1.2 shown in Table 1. Specific measurements were carried out as shown in gt below.

(1) Running performance After running 7L 200 times using a video deck, the running performance was judged based on the degree of snagging and jitter characteristics.

○: Good ×: Poor (2) Tension: A sample tape with a length of 1 m was wound around a glass tube with a diameter of 36 mm as a core, and a load of 1.5 to 9 was applied to it.
b) When the tape is left in an atmosphere at 80% (relative humidity) at 23°C for one hour, then left in an atmosphere at 23°C and 55% (relative humidity) for an hour, and the tape is gently unwound. Judgment was made based on the degree of adhesion. ) In the table, the 0 mark indicates that they do not stick together, the Δ mark indicates that they stick together slightly, and the X mark indicates that they clearly stick together.

(3) Glossiness of cross 00° reflection: The higher the relative value when the standard version is set to 100%, the better the glossiness.

(4) Chroma S/'N Chroma noise (AM) is the chroma signal (3,58MH2)
0.7 ] 4 V, -p, record on the luminance signal, play it back, take out only the chroma signal, and calculate the ratio of the effective noise level to the noise level when the chroma signal is removed. represent.

As is clear from Table 1, the samples of the present invention had good runnability and adhesion, ranking 11th in the bidet! He was a dominant f-sexual.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the elongation rate of the soft polyurethane applied to the magnetic layer and the adhesion resistance of the magnetic layer. Fig. 2 Elongation rate and tensile strength VC of both hard and soft polyurethanes
FIG. FIG. 3 is a diagram showing the relationship between the back surface average roughness σ and the transfer properties e and l jitter % properties. Agent Patent Attorney No 1) Yoshi Sai Figure 1 Figure 2 Figure 2 ＼ □□□−２＼ Load ()) t, cy/cmj Figure 3

Claims (1)

[Claims] A magnetic layer containing a polyurethane resin with an elongation at break of 900% or more is broken on one side of the support, and a support layer is not placed on the other side, and the average surface roughness of the other side is 0015~
0. (Magnetic recording medium that is 125 μm.