JPS5979428A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To eliminate deterioration in shape due to repeated uses in environments of various temps. by using a mixture of a polyurethane resin having hydrophilic groups introduced, especially such a resin having high glass transition point Tg and high dispersibility, and other specified binders mixed in a specified range. CONSTITUTION:The binder is composed of 10-40wt% cellulose deriv. 30- 70wt% polyurethane resin having hydrophilic groups, such as formula I , introduced (M is H, Li, Na, or K, and M' is M or alkyl CnH2n+1), and 5-20wt% butadiene-acrylonitrile copolymer. Especially, as highly dispersible polyurethane resin, the resin having many so-called hard segments in one molecule, and >=30 deg.C glass transition point are used. As a result, hardness of the coat and stiffness of the whole body of a magnetic recording medium are enhanced, deformation is reduced, and thermal stability is also raised.

Description

[Detailed Description of the Invention] The 42 invention relates to a magnetic recording medium suitable for use in magnetic recording tapes for video or audio, nitric disks, etc., and has particularly excellent wear resistance. At the same time, the present invention proposes a magnetic recording medium that is 11 times smaller than the previous one and exhibits less deterioration in shape after repeated operations.

fX-;l:, In order to improve the mechanical and physical properties of a so-called coated magnetic recording medium in which the (1911 layer is coated with magnetic H), various compositions of the binder used therein are used. Research and development is being carried out.

For example, to improve its durability and electromagnetic conversion properties.
It has been proposed that a cellulose derivative, a polyurethane resin, and a butadiene-acrylonitrile copolymer be mixed within a predetermined range.

However, with the advancement of the magnetic recording field, there is a need for magnetic media to further improve its crystal performance and its magnetic properties, and to improve its durability under harsh usage conditions. Historically, the decline in mechanical strength, such as shape deterioration, has become a major problem with the Y+VH'A magnetic recording medium.

In other words, when such shape deterioration occurs, for example, in a video tape, the CTL recorded on both sides of the tape
Disturbances occur in the signal or audio signal. In addition, in recent years, stereo has become the standard, so even slight deterioration in the shape can cause the left and right balance to collapse, which poses a major problem.

The present invention aims to improve the dispersibility and durability of the magnetic layer of a magnetic recording medium in response to the above-mentioned requirements.

In the present invention, especially -3O3M,'-C00M
The above-mentioned problems are solved by mixing and using a polyurethane resin having a high 11''lf content and another specified binder in a +1♀ specific range.

Zunawaji, in the present invention, ζ is formed by coating a magnetic layer mainly composed of magnetic 1'5) and a binder on a non-magnetic support.
However, in the present invention, the polyurethane resin is 30...
M(INlj IMI94 (However, M is tl, L'+
+ Na or M' is It, Li, NB,
K or alkyl group Cn"2n-+-+) and 1 to lyl co-merged with tutadiene-acrylic II 5 to 20ii'i
It consists of f+' L, including J%.

+1°I+' molecule lk t to ltlr! I polyurethane tree 1 finger ζ is preferably a crow transition n;tTg containing many so-called hard segments in the molecule 1″1 case.
The hardness of coating I9 is increased, and the stiffness of the entire magnetic recording medium is reduced to 1.
11. Less distortion and less deformation! ; C) Stabilization is also achieved.

■1 Also, the use of the Citadiene-Crystalline nithole copolymer improves the race linking properties of the magnetic layer O1 and also provides flexibility for coating. -5-4 There is a possibility that this butadiene-acrylic 11 nitrile co-combination will be selected as 5 and 201 [amount%].
At %-A, the results of improved relay links and flexibility are visible, and when this exceeds 20%, the paint film deteriorates! It depends on whether you're being too low-key or not. Further, the content of acryloni[-lyl] in this futasocone-7-acrylonyl-1-lyl combination is preferably 35% since 4596 is compatible with polyurethane by 1% in 111%.

In addition, the reason why the cell 1 course derivative is selected at 10 to 40% is that if it is less than 10%, the shape will deteriorate significantly at commercial temperature and humidity, and if it is less than 40%, the coating film LTL・1 wear and tear 111゛ such as becoming brittle and easily damaged:
In addition, polyurethane resins containing hydrophilic polar groups can be obtained by various methods, such as polyester used in the synthesis of polyurethane, or dicarboxylic acid used as a raw material for polyol. A method using a dicarboxylic acid having a 1011 group at the terminal or side chain of the acid component (method using a dicarboxylic acid having a sulfonic acid group such as 1-5-sulfoisulfoisophthalic acid, or Tan resin and Cg-
Possible methods include reacting a compound represented by CH-C:H-0803M and introducing it by dehydrochlorination reaction. Further, when introducing a polar group into the polyurethane resin, it is preferable that the molecular weight per polar group is in the range of 2,000 to 50,000. The reason for specifying the content p of polyurethane resin on the first and second surfaces to 30 and 707RjFt% is 3 Tsui 1%.
If it is less than 11%, the effect of improvement in 11% and durability will be remarkable, and if it exceeds 70%, the fluidity of the coating will increase and the shape will deteriorate, resulting in 4-12. This is due to the discovery of

7 In addition, as the amphoteric body in the magnetic smear of the magnetic recording medium according to the present invention, conventionally well-known intermediates such as γ-Pe203, Fe3O4, or ferromagnetic CrO7 or F
Alloy magnetic layers such as e, Fe-Co, and Fe-Co-Ni can be used alone or in combination.

In addition, a lubricant, 1II
A polishing agent, an antistatic agent, a fl& agent, etc. may be added.

Here, as the moisturizing agent, for example, solid 111 agents such as various silicone oils, libden disulfide, tunksten disulfide, fatty acid esters, phosphoric acid esters, etc. can be used, but the addition method is a binder. IC) It is desired that 0 city is controlled to 0.1 to 20 city m part with respect to evil.

In addition, for grinding, conventionally known materials such as 1:1 alumina, silicon carbide, 1:1 aluminum oxide, 21 random, etc., which are relatively hard, can be used. The average particle size of the material is preferably 277 m or less.

In addition, as anti-static agents, natural surfactants such as carbon black and saponin, nonions such as alkylene oxide type and glycerin type! /11 Men's Words Ii Agent, 1
Kadmen surfactants such as 1°11-class alkylamines, quaternary ammonium salts, pyridine and other heterocycles,
Carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester group, ν,
) Aconone surfactants containing acidic groups such as acid ester groups, amino acids, aminosulfonic acids, amino alcohols! −
i: ln I of sulfuric acid or phosphoric acid ester q-c+ etc.
Agents such as I11 are used. surface, these interfaces Z! Uniform agents can be used alone or in combination.

These are used as anti-static protection,
Sometimes the purpose is to improve dispersion, wettability/FUI properties, for example.

-, as agents for 11 carbon atoms, such as capric acid, lamelic acid, myristic acid, oleic acid, linoleic acid, etc.
2 to 18 fatty acids, alkali metals of this fatty acid or “
? i) I) using a metal oxide consisting of alkali metals, lecithin, etc.; Incidentally, the dispersant of Gorera is added in a range of 1 to 20 parts per 1 part of 100 parts of binder.

Examples of non-magnetic supports include polyesters such as polyethylene teretulate and voriconyethylene 2,6-buphthalate, polyurethanes such as polypyrene, cellulose triacetate, cellulose diacetate, etc. Cells such as carbon dioxide dielectric, polycarbonate, polyamide, polyimide, etc. are used.

In history, (on another i'l M there are jun i'si i'4f1 people second 1-tsubu=+-), or 41 shidenbo 11-
You can set up a hack layer etc. for this purpose.

Next, embodiments of the present invention will be described, but it is clear that the composition, manufacturing method, etc. thereof are not defined in the embodiments described above.

Example 1 First, magnetic coating 1 having the above composition is prepared.

These 4A materials were kneaded in a ball mill for 24 hours, and then the trifunctional isocyanate compound 1. (11 polyurethane industry; product name) to 20PIIR (parts per hundre)
d parLr, ofre! After adding (in), the mixture was mixed and stirred for 1 hour, and then the non-magnetic support made of polyethylene terevitrate film had a thickness of 5/2 after drying.
! It was applied so that the thickness was m. After that, the original magnetic tape is processed to have a 114'ζ stain and a width of 1/2 inch by magnetic orientation treatment, drying treatment, winding treatment, and calendaring treatment in the same manner as in the case of obtaining ordinary coated magnetic recording media. Cut IJi
1. The magnetic recording medium was 11-.

Examples 2 to 4 Magnetic recording media were obtained in the same manner as in Example 1 except that the composition of the binder was changed.

Table 1 shows Examples 1 to 4 according to the present invention, comparative examples, and the composition of each binder in the conventional example, and the results of measuring the time characteristics of magnetic recording media after calendering. are shown in Table 1.

In the conventional example, the composition of the binder is 30 parts by weight of nitrocellulose, 50 parts by weight of Nistan 57+12 (manufactured by Gutdrich), a conventional polyurethane resin that does not have a hydrophilic polar group introduced, and butadiene-acrylonitrile. This is a case where a 20'*FA portion of a copolymer (acrylonitrile content: 20%) is used. In addition, in Table 1, the hardness (stiffness) of the coating film is a relative value. The material that did not contain the lysyl-dinitrile copolymer showed almost no crushing even after calendering, and the banking property did not improve. Moreover, the defect of the comparative example was that the adhesive strength of the coating film was low.

According to the present invention, it is possible to repeatedly use the seeds under various environmental conditions including (1) excellent stability without deterioration in shape, and (3) excellent electromagnetic conversion characteristics and physical properties as a video tape.
'! It was valued for exhibiting l' properties.

In addition, when using a hardening agent, binder 100Htli'
ii to 5.;((River [It is desirable to add 51 parts.

In Table 1, in the columns of powder drop and shape deterioration, ◎ indicates 15) No lumps or shape deterioration was observed, 4) (X indicates almost no appearance), △ ◎ in the column of surface 1η is extremely good, (J'
JJ+'t), △ indicates slightly inferior, and × indicates iq is inferior.

\ \ \23, ゝ・１、 \

Claims (1)

[Claims] Month: In a magnetic recording medium consisting of a magnetic holding body 1-, a magnetic powder and a binder as main components, the binder C1 is a cell+1-spring. 10-40 dedicated
City resin is 30 to 7 (amount%, butadiene-acrylonitrile co-Y ((combined) contains 5 to 20% of vehicle armor,
Above M1. ．． ill, I, i, Nn or +<, M
' is It, I-+, NalI, or an alkyl group ct+Hzn→-1.