JPH0474774B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a magnetic recording medium, and more particularly to a high-performance magnetic recording medium in which the magnetic layer is formed from a binder and magnetic particles modified with a specific modifier. (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. Various physical properties are required for the magnetic layer, but
A particularly important required performance is good running properties of the magnetic recording medium, and for this purpose it is strongly required that the coefficient of friction between the recording head and the magnetic recording medium be low. 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 coefficient of friction 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 as video tapes, audio tapes, etc. When using the tape, the slipperiness is insufficient, so
When the tape is used at high speeds such as winding and rewinding, it may cause irregular winding, which may cause degeneration or damage to the tape.
This causes dropouts. A method of solving these drawbacks and lowering the coefficient of friction of magnetic recording media is to add lubricants such as fatty acids, wax, and silicone oil to the magnetic layer. However, another drawback arises in that the lubricant added to the magnetic layer bleeds out onto the tape surface, causing clogging of the recording head. As a method to solve the above-mentioned drawbacks, a method has been proposed in which a resin with a low coefficient of friction is used as the binder resin itself, such as a polyurethane resin having a siloxane bond in the molecule (for example, JP-A No. 57-176535 No. 59-94237, No. 59
-5421, 58-218034, 58-222436, 58-218034, 58-222436,
59-11535, 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 silicone compounds. Furthermore, since the polymer is limited to polyurethane resins, there is a problem in that the scope of its use is severely 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 binder 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 fluorine compound having a reactive organic functional group and an organic polyisocyanate, and the modifier is a reaction product of a fluorine compound having a reactive organic functional group and an organic polyisocyanate, This is a magnetic recording medium characterized in that it does not have any characteristics. 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 fluorine compound having a reactive organic functional group and an organic polyisocyanate. and the reaction product is substantially free of free isocyanate groups. Fluorine compounds having reactive organic functional groups used to obtain such modifiers include amino groups,
Any compound may be used as long as it has a group capable of reacting with an isocyanate group such as a carboxyl group, hydroxyl group, thioalcohol group, etc., but a particularly preferred example is a fluorine compound represented by the following formula. (1) H (CF ₂ CF ₂ ) _o CH ₂ OH (n=1 to 7) (2) CF ₃ (CF ₂ CF ₂ ) _o CH ₂ CH ₂ OH (n=1 to
10) (3) CF ₃ (CF ₂ CF ₂ ) _o COOH (n=1 to 10) (4) CF ₃ (CF ₂ CF ₂ ) _o CH ₂ CH ₂ SH (n=1 to
10) (5) H (CF ₂ CF ₂ ) ₁ (CH ₂ ) _n (OCH ₂ CH ₂ (OH)
CH ₂ ) _o OH (1=1 to 10, m=1 to 10, n=
1 to 3) (6) F (CF ₂ CF ₂ ) ₁ (CH ₂ ) _n (OCH ₂ CH ₂ (OH)
CH ₂ ) _o OH (1=1 to 10, m=1 to 10, n=
1 to 3) The fluorine compounds having the above-mentioned reactive organic functional groups are preferred examples of fluorine compounds in the present invention, and the present invention is not limited to these examples. The compound and other fluorine 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 synthetic raw material for 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(phenyl isocyanate), diylylene diisocyanate, 1,5-naphthalene diisocyanate, benzine diisocyanate, o-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-methylene bis (cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, etc.Furthermore, adducts of these organic polyisocyanates and other compounds, such as those having the following structural formula, may be mentioned, but are not limited to these. The modifier used in the present invention is a fluorine compound having a reactive organic functional group as described above and an organic polyisocyanate as described above. Preferably 1:1 so that no residue remains.
from about 0 to 150°C, preferably from 20 to 80°C, in the presence or absence of an organic solvent and a catalyst.
It can be easily obtained by reacting for about 10 minutes to 3 hours at a temperature of .degree. The organic solvent that may be used in the production of such a modifier may be any organic solvent as long as it is inert to each reaction raw material and product. 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, benzene, toluene, xylene, chloroform, carbon tetrachloride, chlorobenzene, perchlorethylene,
Examples include trichlorethylene. 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 various organic solvents. According to various analyzes such as infrared absorption spectroscopy, 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 fluorine compound are For example, when the reactive organic functional group is an amino group, it is clear that the two are bonded through a urethane bond and that the compound is substantially free of free isocyanate groups. Summer. In the present invention, the binder resin used is various conventionally known binder resins, and any of these conventionally known binder resins can be used. For example, vinyl chloride resin, vinylidene chloride resin, vinyl chloride/acetic acid resin, etc. Vinyl/vinyl alcohol copolymer resin, alkyd resin, epoxy resin, acrylonitrile-butadiene resin,
Particularly preferred examples include polyurethane resins, polyurea resins, nitrocellulose resins, polybutyral resins, polyester resins, fluorine resins, melamine resins, urea resins, acrylic resins, and polyamide resins. is a polyurethane resin having urea bonds, urethane bonds, etc. in its structure. These resins can be used alone or as a mixture, and can be used as a solution or dispersion in an organic solvent. The dispersion liquid used in the present invention contains the above-mentioned modifier, magnetic particles, binder resin, and medium as essential components. Examples of magnetic particles used in the present invention include:
Iron, chromium, nickel, cobalt, alloys or oxides thereof, and modified products thereof, specifically, for example, γ-Fe ₂ O ₃ , ferrite, magnetite, CrO ₂ , cobal-doped γ-Fe _{2 O3} ,
Examples include bertolide compounds of Fe ₃ O ₄ and Fe 3 O 4 . The above magnetic particles are merely examples, and
Of course, various magnetic particles other than those exemplified above can also be used in the present invention, and can be used alone or as a mixture. 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 the above-mentioned components as essential components, and their usage ratios are the same as in conventional dispersions of magnetic particles.For example, if the entire dispersion is 100 parts by weight, The magnetic particles occupy about 10 to 50% by weight, the modifier accounts for about 1 to 50% by weight of the binder resin, and the medium accounts for about 50 to 90% by weight.
By weight, the binder resin typically ranges from about 5 to 20% by weight. 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. inhibitors, stabilizers,
Any additives such as foaming 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, while adding the necessary components simultaneously or sequentially, 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 a dispersion method vary depending on the type and size of the magnetic particles to be dispersed, their purpose, etc., but generally the process is carried out at a temperature between room temperature and 100°C for about 5 minutes to 20 hours. Bye. Further, as the support used, any conventionally known support can be used, for example, polyester film, polypropylene film, cellulose triacetate film, cellulose diacetate film, polycarbonate film, etc. with a thickness of 5 to 50 μm can be used arbitrarily. I can do it. The magnetic layer is formed by applying the dispersion as described above to at least one surface of the support as described above by any method so that the thickness when dried is preferably about 5 to 20 μm, and then drying. It can be formed by 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 and electrical properties, depending on the type of binder resin used. Because it has a low coefficient of friction that cannot be achieved with conventional technology while maintaining its physical, chemical, and physical properties, it is used in various magnetic tapes, etc., and can be used at high speeds such as winding and unwinding. Even if the tape is damaged, the tape will not be disturbed, and therefore the tape will not be damaged or broken. Furthermore, the modifier of the present invention is not limited to modifying polyurethane resins, but can be freely used to modify any binder resin, and therefore can be used with various binders without increasing the manufacturing cost of magnetic recording media. It is made of resin and has the advantage of providing a magnetic recording medium with a low coefficient of friction. 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 can be used to form urethane bonds. Because the modifiers are integrated with the binder resin by polar groups such as urea and urea bonds, for example by hydrogen bonds, the modifier does not bleed onto the surface of the magnetic layer over time as in the conventional technology. , the drawbacks of causing various problems have been solved. Next, the present invention will be explained in more detail by giving reference examples, examples, comparative examples, and usage examples. In addition, in the text,
Parts or percentages are by weight. Reference example 1 (Production example of modifier) Adduct of hexamethylene diisocyanate and water (Dyuranate 24A-100, manufactured by Asahi Kasei, NCO%
23.5) While stirring 52 parts at 60°C, 80 parts of fluorinated alcohol having the following structure was gradually removed and reacted, yielding 129 parts of a colorless and transparent liquid modifier (M1). . H(CF ₂ CF ₂ ) ₅ OH According to the infrared absorption spectrum of this modifier,
No absorption due to free isocyanate groups at 2270/cm was observed, and an absorption band due to _-CF2- groups was observed at 1190/cm. Therefore, the main structure of the above modifier is estimated to be the following formula. Reference example 2 (manufacturing example of modifier) Adduct of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate (TD1) (Coronate L, manufactured by Nippon Polyurethane, NCO% 12.5,
While stirring well 120 parts (solid content 75%) at 50℃,
Fluorinated alcohol with the following structure in it
Part 171 is gradually removed and reacted. After completion of the CF ₃ (CF ₂ CF ₂ ) ₃ OH reaction, 251 parts of a transparent liquid modifier (M2) was obtained. According to the infrared absorption spectrum of this modifier,
No absorption due to free isocyanate groups at 2270/cm was observed, and an absorption band due to _-CF2- groups was observed at 1190/cm. Therefore, the main structure of the above modifier is estimated to be the following formula. Reference example 3 (manufacturing example of modifier) Adduct of 1 mol of trimethylolpropane and 3 mol of xylylene diisocyanate (takenate
D110N, Takeda Pharmaceutical, NCO% 11.5, solid content 75%)
While thoroughly stirring 186 parts at room temperature, 258 parts of a fluorinated alcohol having the structure shown below was gradually added thereto and reacted. CF ₃ (CF ₂ CF ₂ ) ₃ CH ₂ CH ₂ SH After the reaction was completed, 384 parts of a transparent liquid modifier (M3) was obtained. According to the infrared absorption spectrum of this modifier,
No absorption due to free isocyanate groups at 2270/cm was observed, and an absorption band due to _-CF2- groups was observed at 1190/cm. Therefore, the main structure of the above modifier is estimated to be the following formula. Reference Example 4 (Preparation of binder resin solution) 150 parts of polybutylene adipate having a molecular weight of 2,000 having a hydroxyl group at the end, 20 parts of 1,3-butylene glycol, and 52 parts of tolylene diisocyanate were subjected to an addition reaction in 412 parts of methyl ethyl ketone to obtain a solution with a viscosity of 200.
Poise/Polyurethane resin solution at 20℃ (solid content 35
%) was obtained. To 100 parts of this polyurethane resin solution,
5 parts of modifier (M1) were added to obtain a modified binder resin solution (UB1). Reference Example 5 (Preparation of Binder Resin Solution) A modified binder resin solution (UB2) was obtained in the same manner as in Reference Example 4 except that the modifier (M2) was used instead of the modifier (M1) in Reference Example 4. Ta. Reference Example 6 (Preparation of binder resin solution) Modified binder resin solution (UB3) was prepared in the same manner as in Reference Example 4, except that the modifier (M3) was used instead of the modifier (M1) in Reference Example 4. Obtained. Reference example 7 (Preparation of dispersion) Co-containing Fe ₂ O ₃ 100 parts polyester type polyurethane resin (35% solution)
54 parts Binder solution (UB1) (35% solution) 20 parts Dispersant (lecithin) 1 part Carbon black 5 parts Nitrocellulose 6 parts Methyl ethyl ketone 270 parts The above ingredients were mixed, kneaded in a ball mill for 50 hours, and further added 8 parts of Coronate L. After further kneading for 3 hours, the kneaded material was passed through a filter to obtain a magnetic particle dispersion (UD1). Reference Example 8 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (UD2) was obtained in the same manner as in Reference Example 7 except that a binder resin solution (UB2) was used instead of the binder resin solution in Reference Example 7. . Reference Example 9 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (UD3) was obtained in the same manner as in Reference Example 7 except that a binder resin solution (UB3) was used instead of the binder resin solution in Reference Example 7. . Reference Example 10 (Preparation of binder resin solution) To 100 parts of a methyl ethyl ketone solution (solid content 30%) of vinyl chloride/vinyl acetate/vinyl alcohol copolymer resin (Eslec A, manufactured by Sekisui Chemical),
3 parts of the modifier (M1) obtained in Reference Example 1 was added to obtain a binder resin solution (VB1). Reference Example 11 (Preparation of binder resin solution) A modified binder resin (VB2) was obtained in the same manner as in Reference Example 10 except that the modifier (M2) was used instead of the modifier (M1) in Reference Example 10. . Reference Example 12 (Preparation of binder resin solution) A modified binder resin (VB3) was obtained in the same manner as in Reference Example 10, except that the modifier (M3) was used instead of the modifier (M1) in Reference Example 10. . Reference Example 13 (Preparation of binder resin solution) A modified binder resin (VB4) was obtained in the same manner as in Reference Example 10, except that the modifier (M4) was used instead of the modifier (M1) in Reference Example 10. . Reference example 14 (Preparation of dispersion liquid) Co-containing Fe ₂ O ₃ 100 parts binder solution (VB1) (30% solution) 20 parts polyester type polyurethane resin solution (Lesamine
ME12, manufactured by Dainichiseika Chemical Industries) 54 parts Dispersant (lecithin) 1 part Carbon black 5 parts Nitrocellulose 6 parts Methyl ethyl ketone 270 parts The above ingredients were mixed and kneaded in a ball mill for 50 hours, then 8 parts of Coronate L was added and an additional 3 hours After kneading, the kneaded mixture was passed through a filter to obtain a magnetic particle dispersion (VD1). Reference Example 15 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (VD2) was obtained in the same manner as in Reference Example 14 except that a binder resin solution (VB2) was used instead of the binder resin solution in Reference Example 14. . Reference Example 16 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (VD3) was obtained in the same manner as in Reference Example 14 except that a binder resin solution (VB3) was used instead of the binder resin solution in Reference Example 14. . Reference example 17 (Preparation of binder resin solution) Butyral resin (Eslec B, manufactured by Sekisui Chemical)
Add 3 parts of the modifier (M1) obtained in Reference Example 1 to 100 parts of the methyl ethyl ketone solution (solid content 30%),
A modified binder resin solution (BB1) was obtained. Reference Example 18 (Preparation of binder resin solution) A modified binder resin (BB2) was obtained in the same manner as in Reference Example 17 except that the modifier (M2) was used instead of the modifier (M1) in Reference Example 17. . Reference Example 19 (Preparation of binder resin solution) A modified binder resin (BB3) was obtained in the same manner as in Reference Example 17, except that the modifier (M3) was used instead of the modifier (M1) in Reference Example 17. . Reference example 20 (Preparation of dispersion liquid) 100 parts Co-containing Fe ₂ O ₃ binder solution (BB1) (30% solution) 20 parts polyester type polyurethane resin solution (Lesamine
ME12, manufactured by Dainichiseika Chemical Industries) 54 parts Dispersant (lecithin) 1 part Carbon black 5 parts Nitrocellulose 6 parts Methyl ethyl ketone 270 parts The above ingredients were mixed and kneaded in a ball mill for 50 hours, then 8 parts of Coronate L was added and an additional 3 hours After kneading, the kneaded mixture was passed through a filter to obtain a magnetic particle dispersion (BD1). Reference Example 21 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (BD2) was obtained in the same manner as in Reference Example 20 except that a binder resin solution (BB2) was used instead of the binder resin solution in Reference Example 20. . Reference Example 22 (Preparation of dispersion liquid) A magnetic particle dispersion liquid (BD3) was obtained in the same manner as in Reference Example 20 except that a binder resin solution (BB3) was used instead of the binder resin solution in Reference Example 20. . Examples 1 to 3 The dispersions UD1 to UD3 obtained in the reference examples were
Each coated with a reverse roll coater to a thickness of 15 μm.
on a polyester film, each with a thickness of 5 μm.
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 4 to 6 The dispersions VD1 to VD3 obtained in the reference examples were
Each coated with a reverse roll coater to a thickness of 15 μm.
on a polyester film, each with a thickness of 5 μm.
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 7 to 9 The dispersions BD1 to BD3 obtained in the reference examples were
Each coated with a reverse roll coater to a thickness of 15 μm.
on a polyester film, each with a thickness of 5 μm.
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. Comparative Examples 1 to 3 Comparative magnetic recording media were obtained in the same manner as in Examples 1 to 9, except that polyurethane resins, Eslec A and Eslec 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 (μk) measured between the magnetic layer and the support (base film), and the other performances were subjected to practical tests as a videotape.
Observations are made of tape squeal (B), jitter lateral wobbling (C), irregular winding during fast forwarding (D), and wear of the magnetic layer (E) during 200 runs. The overall evaluation was given as F.

【table】

【table】

[Table] From the results below, 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 (1)

[Claims] 1 Consisting of a non-magnetic support and a magnetic layer provided on one side of the support, the magnetic layer is formed from a dispersion consisting 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 fluorine compound having a reactive organic functional group and an organic polyisocyanate, and has substantially no free isocyanate groups.