JPS62197920A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To maintain the excellent performance intrinsically possessed by a binder resin and to obtain a titled medium having a low coefft. of friction by forming a magnetic layer of a dispersion consisting of magnetic particles, binder resin, modifying agent for the binder resin and medium. CONSTITUTION:This medium consists of a nonmagnetic base and the magnetic layer provided on one face of the base. The magnetic layer is formed of the dispersion consisting of the magnetic particles, binder resin, modifying agent for the binder resin, and the medium. The modifying agent is the resulted product of reaction of a silicone compd. having a reactive org. functional group and org. polyisocyanate and has at least one free isocyanate group. The org. isocyanate refers to a compd. which has at least two isocyanate groups in an aliphat. or arom. compd. The above-mentioned medium is thereby made to have the low coefft. of friction of the extent which is not attainable with the prior art while the various characteristics intrinsically possessed by the binder resin, for example, strength, electrical, chemical and physical characteristics are retained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic recording medium, and more specifically, the present invention relates to a magnetic recording medium, and more particularly, the present invention relates to a magnetic recording medium, and more specifically, a high-performance magnetic recording medium whose magnetic layer is formed from a binder resin and magnetic particles modified with a specific modifier. Related to magnetic recording media.

(Prior Art) Conventionally, magnetic recording media used in audio equipment, computers, etc. are obtained by forming a magnetic layer made of magnetic particles and a binder resin on a nonmagnetic support such as a polyester film.

Such a magnetic layer is formed by coating a support with a dispersion in which magnetic particles are dispersed in a medium containing a binder resin.

The magnetic layer is required to have various physical properties, but the particularly important required performance is good running properties of the magnetic recording medium, and for this purpose it is strongly recommended that the coefficient of friction between the recording head and the magnetic recording medium be low. required. The level of such friction coefficient is mainly determined by the binder resin used to form the magnetic layer.

Conventionally, as binder resins, vinyl chloride resins, polyurethane resins, polyester resins, nitrocellulose resins, epoxy resins, etc. are mainly used alone or in combination.

(Problem to be Solved by the Invention) The yi friction coefficient of the binder resins conventionally used as described above is generally 0.4 or more, and magnetic recording media formed from these binder resins can be used for video tapes, audio When used as a tape, etc., the slipperiness of the tape is insufficient, so when the tape is used at high speeds such as winding and unwinding, it may wind irregularly, causing deformation, damage, etc. of the tape, and causing drops. This is causing the out.

As a method to solve these drawbacks and lower the coefficient of friction of magnetic recording media, fatty acids, wax,
A method of adding a lubricant such as silicone oil has been used, but another disadvantage of this method is that the lubricant added to the magnetic layer bleeds out onto the tape surface, causing clogging of the recording head. occurs.

As a method to solve the above drawbacks, it has been proposed to use a resin with a low coefficient of friction as the binder resin itself, such as a polyurethane resin with siloxane bonds in the molecule (for example, JP-A-57 -176535
No. 59-94237, No. 59-5421, No. 5
No. 8-218034, No. 58-222436, No. 59
-11535, Publication No. 59-82636, etc.)
.

According to such a method, a magnetic layer with a relatively low coefficient of friction can be formed, but since the polyurethane resin having siloxane bonds contains siloxane bonds in the main chain of the polymer, sufficient reaction cannot be achieved. It is difficult to obtain a binder resin of constant quality, the price is high, and various problems arise due to unreacted silicon compounds.

Furthermore, since the polymer is limited to polyurethane resins, there is a problem in that the range of use thereof is significantly limited.

As a result of intensive research in order to solve the above-mentioned drawbacks of the conventional technology and meet the above-mentioned demands, the present inventor has discovered that when modifying a binder resin using a specific modifier when manufacturing a magnetic recording medium, The present invention was developed based on the discovery that the above-mentioned drawbacks of the prior art are solved, the binder resin is not limited to polyurethane resins, various pinter resins can be easily used, and a magnetic recording medium with a low coefficient of friction can be provided. completed.

(Means for Solving the Problems) That is, the present invention comprises a non-magnetic support and a magnetic layer provided on one surface of the support, and the magnetic layer includes magnetic particles, a binder resin, and a binder resin. The modifier is a reaction product of a silicone compound having a reactive organic functional group and an organic polyisocyanate, and at least one free isocyanate is formed from a dispersion comprising a modifier and a medium. A magnetic recording medium characterized by having a base.

To explain the present invention in more detail, the binder resin modifier used in the present invention and which primarily characterizes the present invention is a reaction product of a silicone compound having a reactive fabric functional group and an organic polyisocyanate. and the reaction product is 1
It has at least one 'ji separated isocyanate group in the molecule.

Preferred examples of the silicone compound having a reactive organic functional group used to obtain such a modifier include the following compounds.

(1) Amino modified silicone oil (m=l~IQ, n=2~10, R=C)13 or DC)13) (m=1-10, n=2~10.R=CH
3 or OCH3) (m=0-200) CH3 82NC3)18si[(OSi)nOcH3]3CH
3 (n=2-10) (branch point -2-3, R-lower alkyl group, 1!λ~
2o.

, t-z ~200.1l-2-2o6) (n=1
~200, R-lower alkyl group) (2) Epoxy-modified silicone oil tljl, l11jlU (n ~200) CH3CH3 (m = 1 ~ l01n = 2 ~ 10) (n = 1 ~ 200) (branch point = 2-3.R-lower alkyl group, l=2-2o
.

, ta-2-20o, n*2~2oo) (CH3)
3SiO(SiO)msi(CH3)3J3 (n!1~10) Yo(C)+3)3SiO(SiO)m[5i(CH3)2
0]n5i(CH3)3CH3 (m=1-10, n=2-10) (3) Alcohol-modified silicone oil (n=1-20
0) (m=1-10. n=2-10) / l CH3CH3 (n=0-200) CH3 (+=1-10, m=l1O-200.n-1-5) (
n=1-200, R=lower alkyl) (4) Mercapto-modified silicone oil (m=1-1G, n=2-1
0) 3H6SH (CH3)3SiO(SiO)nSi(CH3)3■ CH3 (n=2-10) (branch point = 2-3. R = lower alkyl group, I = 2-.
! D.

, m=2-260. n=2-200)(n=1-2
00, R = lower alkyl group) (5) Carboxyl-modified silicone oil (m = 1 to 10. n = 2 to 10) (n = 1 to 200) (branch point = 2 to 3. R-lower alkyl group, macro λ~200
, m=2~20Q, n=2-27'') (n=1~2
00, R-lower alkyl group) The silicone compounds having the above-mentioned reactive organic functional groups are preferred examples of silicone compounds in the present invention, and the present invention is not limited to these examples. The exemplified compound and other silicone compounds are currently commercially available and readily available from the market, and any of them can be used in the present invention.

The organic polyisocyanate used in the present invention and which is the second characteristic of the present invention is a compound having at least two isocyanate atoms in an aliphatic or aromatic compound, and has traditionally been used as a raw material for the synthesis of polyurethane resins. Widely used.

Any of these known organic polyisocyanates are useful in the present invention. Particularly preferred organic polyisocyanates are as follows.

Toluene-2,4-diisocyanate, 4-methoxy-
1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate-diphenyl ether, mesitylene diisocyanate , 4.4-methylenebis(phenylisocyanate), shrylene diisocyanate, 1.5-naphthalene diisocyanate, benzidine diisocyanate, 0-nitrobenzidine diisocyanate, 4.4-dibenzyl diisocyanate, 1.4-tetramethylene diisocyanate.

1.6-tetramethylene diisocyanate, 1.10-
decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, and adducts of these organic polyisocyanates with other compounds, For example, the following structural formula may be mentioned,
Not limited to these.

GUN)I(C)12)6NGO OCH3 The modifier used in the present invention is a silicone compound having a reactive organic functional group as described above and an organic polyisocyanate as described above. and the functional group ratio such that one or more anate groups, preferably 1 to 2, are in excess in one molecule, in the presence or absence of an organic solvent and a catalyst, from about θ to 150°C, preferably It can be easily obtained by reacting at a temperature of 20 to 80°C for about 10 minutes to 3 hours.

The organic solvent that may be used in the production of such a modifier may be any organic solvent that is inert to the respective reaction raw materials and products. For example, preferred organic solvents include methyl ethyl ketone, methyl -n-
Propyl ketone, methyl isobutyl ketone, diethyl ketone, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, cyclohexane, tetrahydrofuran, dioxane, methanol,
Ethanol, isopropyl alcohol, butanol, methyl cellosolve, butyl cellosolve, cellosolve acetate, dimethylformamide, dimethyl sulfoxide,
Pentane, hexane, cyclohexane, heptane, octane, mineral spirits, petroleum ether, gasoline,
Examples include benzene, toluene, xylene, chloroform, carbon tetrachloride, chlorobenzene, perchloroethylene, trichlorethylene and the like.

When the modifier obtained as described above and used in the present invention is produced using an organic solvent, it may be separated from the organic solvent, or it can be used as a solution of the organic solvent. The modifier used in the present invention separated from the organic solvent is generally in the form of a white to brown liquid or solid, and is easily soluble in organic solvents used to disperse various magnetic particles.

According to various analyzes such as infrared absorption spectrum, elemental analysis, and molecular weight measurement, the modifier used in the present invention as described above shows that the isocyanate group of the organic polyisocyanate and the reactive organic functional group of the silicone compound are added together. For example, when the reactive organic functional group is an amino group, the two are bonded through an -NHCONH- bond, and the compound has at least one free isocyanate group in one molecule. It became clear.

According to detailed research by the present inventor, the modifier used in the present invention has an isocyanate of 'FL#1,
For example, it is reactive with various binder resins having hydroxyl groups, primary to secondary amino groups, amide groups, carboxyl groups, etc. It has been found that when the binder resin forms a magnetic layer, the coefficient of friction of the magnetic layer can be significantly lowered without reducing the various properties originally associated with the binder resin. .

Furthermore, this unexpected effect is due to the fact that the modifier used in the present invention has free isocyanate groups.
This is thought to be because the isocyanate groups before, during, or after the formation of the coating film also act as a type of modifier that reacts with each other or with the binder resin.

The dispersion liquid used in the present invention contains the above-mentioned modifier, magnetic particles,
Binder resin and medium are essential components.

The magnetic particles used in the present invention include, for example, iron, chromium, nickel, cobalt, alloys or oxides thereof, and modified products thereof, specifically, for example, γ
Examples include -Fe2O3, ferrite, magnetite, CrO2, and bertolide compounds of cobalt-doped γ-Fe2O3 and Fe3O4.

The above-mentioned magnetic particles are merely examples, and various magnetic particles other than the above-mentioned examples can of course be similarly used in the present invention, and can be used alone or as a mixture.

In the present invention, binder resins used include various binder resins conventionally used for forming magnetic layers, and any of these binder resins can be used. based resin,
Vinyl chloride/vinyl acetate/vinyl alcohol copolymer resin, alkyd resin, epoxy resin, acrylonitrile-butadiene resin, polyurethane resin, polyurea resin, nitrocellulose resin, polybutyral resin, polyester resin, silicone resins, melamine-based resins, urea-based resins, acrylic-based resins, polyamide-based resins, etc., and particularly preferred are resins having reactive groups as described above that can react with isocyanate groups in their structures. . These resins can be used alone or as a mixture, and can be used as a solution or dispersion in an organic solvent.

Further, the reaction between the binder resin and the modifier is performed in the presence or absence of an organic solvent and a catalyst at a temperature of about θ to 150
This can be easily carried out by reacting at a temperature of 20 to 80°C, preferably 20 to 80°C, for about 10 minutes to 3 hours.

The medium used in the present invention is the organic solvent used in the preparation of the modifier described above or a mixture thereof.

The dispersion used in the present invention has one or more components as essential components, and the proportions used are the same as in conventional dispersions of magnetic particles.For example, if the entire dispersion is 100 parts by weight, The magnetic particles in it are approximately 10 to 50% by weight.
The modifier is about 1 to 50% by weight of the binder resin,
The medium is about 50-90% by weight and the binder resin is about 5-90% by weight.
A range of 20% by weight is common.

As long as the dispersion used in the present invention contains these components as essential components, other subcomponents other than those mentioned above, such as pigments, extender pigments, plasticizers, antistatic agents, surfactants, lubricants, crosslinking agents, aging agents, etc. Optional additives such as inhibitors, stabilizers, blowing agents, and antifoaming agents may be included.

The method for producing the dispersion liquid used in the present invention, which consists of the above-mentioned essential components and optional components, may be any conventionally known method, and generally, the necessary components are added simultaneously or sequentially, and the method includes ball milling, mixer treatment, etc. Mixing and dispersing methods such as processing, roll milling, bead milling, gravel milling, sand milling, and high speed impeller processing are suitable.

The conditions for such dispersion methods themselves vary depending on the type and size of the magnetic particles to be dispersed, their purpose, etc.
Generally, the treatment may be carried out at a temperature of room temperature to 100° C. for about 5 minutes to 20 hours.

In addition, in the above-mentioned present invention, when using a binder resin having a group capable of reacting with an isocyanate group, such as a hydroxyl group, an amino group, a carboxyl group, etc., the modifier used in the present invention and these The binder resin may be reacted before, during or after the preparation of the dispersion; the most preferred embodiment is one in which the modifier and the binder resin are reacted in advance in preparing the dispersion. Such a reaction can be carried out by reacting at a temperature of 0 to 120°C, preferably 40 to 80°C, for about 0.5 to 10 hours in the presence or absence of an organic solvent and a catalyst. In addition, in the present invention, a binder resin that does not have a group that reacts with isocyanate groups may be used. In such a case, the modifiers themselves may be combined with each other, or with a di- or polyfunctional compound, e.g. , water or polyamine increases the molecular weight of the modifier, producing similar effects.

In addition, any conventionally known supports can be used, such as polyester films with a thickness of 5 to 504 m, polypropylene films, cellulose triacetate films, cellulose diacetate films,
Polycarbonate film or the like can optionally be used.

The magnetic layer is formed by coating the above-mentioned dispersion on at least one side of the above-mentioned support by an arbitrary method so that the dry thickness thereof is preferably about 5 to 204 m, It can then be formed by drying. The coating method and drying method may be any conventionally known method.

(Function/Effect) The magnetic recording medium of the present invention obtained as described above has various properties inherent to the binder resin, such as strength, electrical resistance, etc., depending on the type of binder resin used. Because it has a low coefficient of friction that cannot be achieved with conventional technology while retaining its chemical and physical properties, it is used in various magnetic tapes, etc., and can be used at high speeds such as winding and unwinding. The tape will not be disturbed even when the tape is used, and therefore the tape will not be damaged or damaged.

Furthermore, the modifier used in the present invention does not become the main chain of the binder resin, but rather binds to the binder resin and becomes the side chain of the binder resin, so it is different from conventional polyurethane resins containing siloxane bonds. The modifier of the present invention is not limited to modifying polyurethane resins, but can be freely used to modify any binder resin. Therefore, there is an advantage that a magnetic recording medium made of various binder resins and having a low coefficient of friction can be provided without increasing the manufacturing cost of the magnetic recording medium.

Furthermore, since the magnetic layer of the magnetic recording medium of the present invention is formed from a dispersion containing the above-mentioned modifier, after the magnetic layer is formed, the modifier contained in the magnetic layer is mixed with the modifier. However, because the modifier reacts with the binder resin, has a high molecular weight, and is integrated with the binder resin, the modification agent bleeds onto the surface of the magnetic layer over time, causing various problems, as in the conventional technology. has been resolved.

Next, the present invention will be explained in more detail by giving reference examples, examples, comparative examples, and usage examples. Note that parts and percentages in the text are based on weight.

Reference Example 1 (Production Example of Modifier) Adduct of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate (TDI) (Coronate L, manufactured by Nippon Polyurethane, NC 0% 12.5, solid content 75%) 1
While thoroughly stirring 75 parts at 50° C., 880 parts of terminal aminopropyl polydimethylsiloxane (molecular weight: 2.200) having the following structure is gradually dropped into the mixture and reacted.

H3 H2NC3)16si[(OSi)noCH3]3H3 (n is the value that makes the molecular weight 2,200) After the reaction, ethyl acetate is evaporated to form a transparent liquid modifier (Ml
) 976 parts were obtained.

According to the infrared absorption spectrum of this modifier, 2270/
The absorption by free isocyanate groups of cm remains;
It showed an absorption band due to 5i-0-C group at 1090/cm. Furthermore, when the free isocyanate groups in this modifier were quantified, the theoretical value was 0.83%, whereas
The actual value was 0.78%.

Therefore, the main structure of the above modifier is estimated to be the following formula.

N) 100-X Reference Example 2 (Production example of modifier) 24 parts of phenyl isocyanate was added to 196 ffl of terminal hydroxypropyl polydimethylsiloxane (molecular weight 980) having the following structure, and the mixture was stirred well at 60°C to form a transparent liquid. 213 parts of reaction product (A) were obtained.

(n is the value at which the molecular weight is 980) Next, an adduct of hexamethylene diisocyanate and water (Schuraney)
24A-100, manufactured by Asahi Kasei Co., Ltd., NC0% 23.5) While stirring well at 60°C, 220 parts of the above reaction product (A) was gradually added dropwise to react, resulting in a colorless and transparent liquid modified product. 263 parts of agent (M2) were obtained.

According to the infrared absorption spectrum of this modifier, 22707
The absorption due to the free isocyanate group at cm remained, and an absorption band due to the 5t-0-C group was shown at 1090/cm. Furthermore, when the amount of free isocyanate groups in this modifier was quantified, the theoretical value was 1.54%, whereas the actual value was 1.37%.

Therefore, the main structure of the above modifier is estimated to be the following formula.

C0NH(CH2)8NHGO-X Reference Example 3 (Production Example of Modifier) Terminal aminopropyl polydimethylsiloxane (molecular weight 1.150) having the following structure 230! 15 parts of n-butyraldehyde was added to the mixture, stirred thoroughly at 80°C, and reacted for 3 hours while removing the generated water from the system under reduced pressure to obtain a transparent liquid reaction product (B) 238 part was obtained.

(n is the value at which the molecular weight is 1,150) Next, an adduct of 1 mole of trimethylolpropane and 3 moles of xylylene diisocyanate (Takenate DIION, manufactured by Wind Pressure Yakuhin, NC0%11, 5. Solid content 75%) ) was stirred well at room temperature, and the above reaction product (
B) 490 parts were gradually added dropwise and reacted at 60°C.

After the reaction was completed, ethyl acetate was evaporated to obtain 610 parts of a transparent liquid modifier (M3).

According to the infrared absorption spectrum of this modifier, 2270
The absorption due to the free isocyanate group at /cm remained, and an absorption band due to the 5i-0-C group was shown at 1090/cm. In addition, when the free isocyanate groups in this modifier were quantified, the theoretical value was 1.34%, while the actual value was 1.25%. Therefore, the main structure of the above modifier is , is estimated as the following formula.

Reference Example 4 (Manufacturing Example of Modifier) 2.6-) While stirring 35 parts of lylene diisocyanate and 110 parts of ethyl acetate at 60°C, a terminal mercaptopropyl polydimethylsiloxane having the following structure (molecular weight 1. 580) 316 parts were gradually added dropwise to react.

(1, m, and n are values that give a molecular weight of 1,580) After the reaction was completed, ethyl acetate was evaporated to obtain 340 parts of a transparent liquid modifier (M4).

According to the infrared absorption spectrum of this modifier, 2270/
The absorption by free isocyanate groups of Cm remains,
It showed an absorption band due to 5i-0-C group at 1090/cm. Furthermore, when quantifying the free isocyanate groups in this modifier, the theoretical value was 2.39%, whereas
The actual value was 2.12%.

Therefore, the main structure of the above modifier is estimated to be the following formula.

(1, m, n are values that give a molecular weight of 1,580) Reference Example 5 (Production example of modifier) 52 parts of hexamethylene diisocyanate and 1 part of ethyl acetate
While stirring well at 60° C., 450 parts of terminal hydroxypropyl polydimethylsiloxane (molecular weight: 2.250) having the structure shown below are gradually added dropwise to 60 parts to react.

(n is the value that gives a molecular weight of 1.580) After the reaction is complete, evaporate the ethyl acetate to form a transparent liquid modifier (M5
) 488 parts were obtained.

According to the infrared absorption spectrum of this modifier, 22707
The absorption due to free isocyanate groups in cm remains,
It showed an absorption band due to the 5t-0-C group at 1090/cm. Furthermore, when the amount of free isocyanate groups in this modifier was quantified, the theoretical value was 1.67%, whereas the actual value was 1.52%.

Therefore, the main structure of the above modifier is estimated to be the following formula.

Reference Example 6 (Preparation of binder resin solution) Polybutylene adipate 15 with a molecular weight of 2.000 having a hydroxyl group at the end
0 parts of 1.3-butylene gellicol, 20 parts of tolylene diisocyanate, and 52 parts of tolylene diisocyanate were subjected to an addition reaction in 412 parts of methyl ethyl ketone to obtain a polyurethane resin solution (solid content 35%) with a viscosity of 200 voids/20°C. Add 5 parts of modifier (Ml) to 100 parts of this polyurethane resin solution,
The reaction was carried out at 0° C. for 3 hours to obtain a modified binder resin solution (UB 1) in which a modifier and a polyurethane resin were combined.

In the binder resin obtained above, no isocyanate group was observed by infrared absorption spectrum. This is presumed to be because the modifier was graft-bonded to the binder resin.

Reference Example 7 (Preparation of binder resin solution) Using a modifier (Ml) instead of the modifier (Ml) in Reference Example 6,
The other conditions were the same as in Reference Example 6, and the modified binder resin solution (U
B2) was obtained.

Reference Example 8 (Preparation of binder resin solution) In place of the modifier (Ml) in Reference Example 6, a modifier (M3) was used,
The other conditions were the same as in Reference Example 6, and the modified binder resin solution (U
B3) was obtained.

Reference Example 9 (Preparation of binder resin solution) In place of the modifier (Ml) in Reference Example 6, a modifier (M4) was used,
Other than that, the modified binder resin solution (υ
B4) was obtained.

Reference Example 10 (Preparation of Binder Resin Solution) A modified binder resin solution (
UB5) was obtained.

Reference Example 11 (Preparation of dispersion) Co-containing Fe2O3 100 parts Binder solution (UBI) (35% solution) 30 parts Dispersant (lecithin) 1 part Carbon black 5 parts Nitrocellulose 6 parts Methyl ethyl ketone
Mix 270 parts of the above ingredients and mill 5 parts in a ball mill.
After kneading for 0 hours, 8 parts of Coronae) L was added, and mixing was continued for a further 3 hours, and the kneaded mixture was passed through a filter to obtain a magnetic particle dispersion (UDI).

Reference Example 12 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (UO2) was obtained in the same manner as in Reference Example 11 except that a binder resin solution (UB2) was used instead of the binder resin solution in Reference Example 11. .

Reference Example 13 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (UO3) was obtained in the same manner as in Reference Example 11 except that a binder resin solution (UB3) was used instead of the binder resin solution in Reference Example 11. .

Reference Example 14 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (UO4) was obtained in the same manner as in Reference Example 11 except that a binder resin solution (UB4) was used instead of the binder resin solution in Reference Example 11. .

Reference Example 15 (Preparation of dispersion liquid) Instead of the binder resin solution in Reference Example 11, the binder resin solution (UB5) was used, and the others were as in Reference Example 11.
A dispersion liquid (UO5) of magnetic particles was obtained in the same manner as above.

Reference Example 1B (Preparation of Binder Resin Solution) The solution obtained in Reference Example 1 was added to 100 parts of a methyl ethyl ketone solution (solid content 30%) of vinyl chloride/vinyl acetate/vinyl alcohol copolymer resin (S-LEC A, manufactured by A-Sui Kagaku). Modifier (Ml
) and reacted at 80°C for 3 hours to obtain a modified binder resin solution (VBI) in which the modifier and vinyl resin were combined.
) was obtained.

In the binder resin obtained above, no isocyanate group was observed by infrared absorption spectrum. This is presumed to be because the modifier was graft-bonded to the binder resin.

Reference Example 17 (Preparation of Binder Resin Solution) A modified binder resin (
VB2) was obtained.

Reference Example 18 (Preparation of Binder Resin Solution) A modified binder resin (
VB3) was obtained.

Reference Example 19 (Preparation of Binder Resin Solution) A modified binder resin (
VB4) was obtained.

Reference Example 20 (Preparation of Binder Resin Solution) A modified binder resin (
VB5) was obtained.

Reference Example 21 (Preparation of dispersion liquid) 100 parts of Co-containing Fe2O3 Binder solution (VBI) (30% solution) 20 parts Polyester type polyurethane resin solution (Rezamin ME1
2. Dainichiseika Kogyo: W) 54 part dispersant (
Lecithin) 1 part carbon black 5 parts nitrocellulose
6 parts methyl ethyl ketone
270 parts of the above ingredients were mixed, kneaded for 50 hours in a ball mill, further added 8 parts of Coronae L, kneaded for a further 3 hours, and passed through a filter to form a magnetic particle dispersion (
VDI) was obtained.

Reference Example 22 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (VO2) was obtained in the same manner as in Reference Example 21 except that a binder resin solution (VB2) was used instead of the binder resin solution in Reference Example 21. .

Reference Example 23 (Preparation of dispersion liquid) A dispersion liquid (VO3) of magnetic particles was obtained in the same manner as in Reference Example 21 except that a binder resin solution (VB3) was used instead of the binder resin solution in Reference Example 21. .

Reference Example 24 (Preparation of dispersion liquid) A dispersion liquid (VO2) of magnetic particles was obtained in the same manner as in Reference Example 21 except that a binder resin solution (VB4) was used instead of the binder resin solution in Reference Example 21. .

Reference Example 25 (Preparation of dispersion liquid) Instead of the binder resin solution in Reference Example 21, the binder resin solution (VB5) was used, and the rest were as in Reference Example 21.
A dispersion liquid (VO5) of magnetic particles was obtained in the same manner as above.

Reference Example 2B (Preparation of binder resin solution) 7 parts of the modifier (Ml) obtained in Reference Example 1 was added to 100 parts of a methyl ethyl ketone solution (solid content 30%) of butyral resin (S-LEC B, manufactured by Mikki Kagaku), and 80 parts of the modifier (Ml) obtained in Reference Example 1 was added. React at ℃ for 3 hours,
A modified binder resin solution (BBI) in which a modifier and a butyral resin were combined was obtained.

In the binder resin obtained above, no isocyanate group was observed by infrared absorption spectrum. This is presumed to be because the modifier was graft-bonded to the binder resin.

Reference Example 27 (Preparation of Binder Resin Solution) A modified binder resin (
BH3) was obtained.

Reference Example 28 (Preparation of Binder Resin Solution) A modified binder resin (
BH3) was obtained.

Reference Example 29 (Preparation of Binder Resin Solution) A modified binder resin (
BH3) was obtained.

Reference Example 30 (Preparation of binder resin solution) Modifier (M5) was used in place of the modifier (Ml) in Reference Example 26, and the modification/heingu resin (BH3) was modified in the same manner as in Reference Example 2G. Obtained.

Reference Example 31 (Preparation of dispersion liquid) 100 parts of Co-containing Fe2O3 Binder solution (BBI) (30% solution) 20 parts Polyester type polyurethane resin solution (Rezamin ME1
2. Dainichiseika Kogyo) 54 parts dispersant (lecithin) 1 part carbon black
5 parts nitrocellulose
6 parts methyl ethyl ketone 2
70 parts of the above ingredients were mixed, kneaded for 50 hours in a ball mill, further added 8 parts of Coronate L, kneaded for another 3 hours, passed the kneaded mixture through a filter, and obtained a dispersion of magnetic particles (BD
I) was obtained.

Reference Example 32 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (BD2) was obtained in the same manner as in Reference Example 31 except that a binder resin solution (BH3) was used instead of the binder resin solution in Reference Example 31. .

Reference Example 33 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (BD3) was obtained in the same manner as in Reference Example 31 except that a binder resin solution (BH3) was used instead of the binder resin solution in Reference Example 31. .

Reference Example 34 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (BO2) was obtained in the same manner as in Reference Example 31 except that a binder resin solution (BH3) was used instead of the binder resin solution in Reference Example 31. .

Reference Example 35 (Preparation of Dispersion Liquid) A magnetic particle dispersion liquid (BH5) was obtained in the same manner as in Reference Example 31 except that a binder resin solution (BH5) was used instead of the binder resin solution in Reference Example 31. .

Examples 1 to 5 The dispersion liquid UDI-UD5 obtained in the reference example was coated on a polyester film with a thickness of 15 μLm each using a reverse roll coater so that the thickness was 54 m, and the solvent was dried. Thereafter, the surface was processed using a super calendar roll and cut into a predetermined width to obtain magnetic recording media of the present invention.

Examples 6 to 10 The dispersion liquid MDI-VD5 obtained in the reference example was coated on each polyester film with a thickness of 15 pm using a reverse roll coater so that the thickness was 54 m,
After drying the solvent, the surface was processed using a super calendar roll and cut into a predetermined width to obtain magnetic recording media of the present invention.

Examples 10 to 15 The dispersions BDI to BD5 obtained in the reference examples were coated on polyester films each having a thickness of 15 tons using a reverse roll coater to a thickness of 51 Lm. After drying, the surface was processed with a super calendar roll and cut into a predetermined width to obtain the magnetic recording medium of the present invention.

Comparative Examples 1 to 3 Comparative magnetic recording media were obtained in the same manner as Examples 1 to 15, except that polyurethane resins, S-LEC A and S-LEC B, which were not modified with the modifier of the present invention were used.

Usage Example The performance of the magnetic recording media of the above Examples and Comparative Examples was investigated and the following results were obtained.

The coefficient of friction (A) is the value (tk) measured between the magnetic layer and the support (base film). The results show observations of tape squeal (B), jitter lateral wobbling (C), irregular winding of the tape during fast forwarding (D), and wear of the magnetic layer (E). The overall evaluation was given as F.

Recording body ABCDEF Comparative example 10.52 Yes Yes Yes Yes Bad example 1 0.15 No No No No No Good example 20.22 No No None No Good example 30.20 No No No No Good example 40.13 No None None None Good example 5
0.08 None None None None Good comparative example 20
．． 28 Small No No Stacked stone Small Example 60.1
5 None None None None Good Example 7 Q, 1
8 Focus None None None Good example 8 0.2
0 None None None None Good Example 90.17 None None None None Good Example 1
00.22 None None None None Good comparative example 3
0.32 Slightly Slightly Slightly Slightly Right Slightly Right Stacked Stone Slightly Good Example 110
．． 20 None None None None Good example 120
．． 17 None None None None Good example 130
．． 21 None None None None Good example 140
．． 12 None None None None Good example 150
．． 13 None None None From the results above, it is clear that the magnetic recording medium of the present invention has a low coefficient of friction of the magnetic layer and exhibits excellent running characteristics.

Claims (2)

[Claims] (1) Consists of a non-magnetic support and a magnetic layer provided on one side of the support, where the magnetic layer is formed from a dispersion of magnetic particles, a binder resin, a modifier for the binder resin, and a medium. A magnetic recording medium, wherein the modifier is a reaction product of a silicone compound having a reactive organic functional group and an organic polyisocyanate, and has at least one free isocyanate group. (2) The magnetic recording medium according to claim (1), wherein the binder resin has a group capable of reacting with an isocyanate group.