JP2001006163A - Analyzing method of adsorption compound of coating layer containing inorganic powders - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze an organic compound or the like bonded to a compound inorganic powder that forms a salt by adsorption or chemical reaction with an inorganic powder on a surface of a coating layer containing the inorganic powder. SOLUTION: In this compound analyzing method, after a supporting member on which a coating layer is formed is allowed to react with a solution so that substances that are not adsorbed are extracted and removed, a surface of the coating layer is measured by means of an X-ray photoelectron spectroscopy apparatus. Then, after a derivative-generating reagent is added so that an absorbed compound on the surface of an inorganic powder is reacted and removed, the surface of the coating layer is measured by means of the X-ray photoelectron spectroscopy apparatus. Thus, based on a difference in measured values obtained prior to and after the treatment with the derivative-generating reagent, a compound that forms a salt by adsorption or chemical reaction can be analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic recording medium having at least a coating layer containing an inorganic powder on a support, particularly a magnetic layer containing a ferromagnetic powder and a binder. The present invention relates to a method for measuring a compound forming a salt by a chemical reaction.

[0002]

2. Description of the Related Art In general, dispersion is required to prepare a coating material containing an inorganic powder. However, in order to highly disperse and prevent agglomeration, it is necessary to modify the surface. It is known that an inorganic compound is mixed with an organic compound having a polar group as one of surface modification methods. In order to improve the characteristics of a coating type magnetic recording medium in which the magnetic layer is formed of a composition containing a magnetic powder, the magnetic layer and the non-magnetic layer are provided with a higher fatty acid or an organic compound which is a lubricant for imparting slidability. Many surface modifiers such as phosphorus compounds and other compounds having polar groups are compounded. Each of these compounds has an acidic polar group, and adsorbs or reacts at a basic point of a magnetic substance or other inorganic powder mixed in a magnetic layer or a non-magnetic layer to form a salt. Conceivable. Since these compounds are strongly adsorbed or reacted with magnetic substances and inorganic powders, it is difficult to extract them with organic solvents.
It was necessary to react with an acid such as hydrochloric acid or an alkali to desorb the adsorbed or reacting substances, and to perform extraction.

The present inventors have conducted intensive studies and as a result, found in Japanese Patent Application No.
No. 11506 proposes a method for separating a compound which forms a derivative and separates it from a magnetic layer as a method for separating a compound which forms a salt by adsorption or chemical reaction with an inorganic powder, particularly a ferromagnetic powder. As a derivatization reagent, the use of a silylating agent commonly used in gas chromatography analysis was examined. As a result, it was found that the object can be achieved by reacting with an organic phosphoric acid compound having no active hydrogen or a metal salt of a fatty acid, which has been considered impossible in the past, to form a derivative. A derivatization reagent is allowed to act on these coating layers, and it is possible to separate and detect a polar compound which forms a salt by adsorption or chemical reaction on a magnetic substance or other inorganic powder as a derivative.

However, this method is suitable for the analysis of polar compounds in the coating layer or the entire magnetic layer, but the magnetic substance or other inorganic substance present in the coating layer surface or the magnetic layer surface, which is considered to be most related to the characteristics. An index of the amount of the compound forming a salt by adsorption or chemical reaction on the powder could not be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a magnetic recording medium or the like in which a coating layer containing an inorganic powder is formed on a support. It is intended to provide a method for measuring the amount of a compound forming a salt by adsorption or chemical reaction, and to provide a method for evaluating a magnetic recording medium having excellent characteristics by measuring the amount of a polar compound. .

[0006]

According to the present invention, a salt is formed by adsorption or chemical reaction on the inorganic powder on the surface of a coating layer in which at least a coating layer comprising an inorganic powder and a binder is provided on a support. In the method for analyzing a compound, a substance on the surface of a coating layer is measured by an X-ray photoelectron spectrometer after extracting and removing an unadsorbed substance from a support provided with the coating layer with a solvent, and then a derivatizing reagent is added to the inorganic material. After reacting and removing the adsorbed compounds on the powder surface, the substance on the coating layer surface is measured with an X-ray photoelectron spectrometer, and the salt is formed by adsorption or chemical reaction based on the difference between the measured values before and after the treatment with the derivatizing reagent. This is a method for analyzing an adsorbed compound on the surface of an inorganic powder-containing coating layer, characterized by analyzing the compound present. This is a method for analyzing an adsorbed compound on the surface of the inorganic powder-containing coating layer, wherein the coating layer is a magnetic layer of a magnetic recording medium containing ferromagnetic powder. This is a method for analyzing an adsorbed compound on the surface of an inorganic powder-containing coating layer, wherein the derivatization reagent is a silylating agent. This is a method for analyzing the adsorbed compound on the surface of the inorganic powder-containing coating layer, wherein the compound adsorbed on the inorganic powder is a fatty acid.

In a magnetic recording medium having a magnetic layer containing a magnetic powder and a binder formed on a support, the magnetic recording medium is reacted with a solvent to extract and remove unadsorbed substances, and then a derivatizing reagent is added. After reacting and removing the compound which forms a salt by adsorption or chemical reaction with the inorganic powder, the substance on the surface of the coating layer is measured with an X-ray photoelectron spectrometer to obtain a carbon / magnetic metal ratio, After adding a derivatizing reagent and reacting and removing a compound that forms a salt by adsorption or chemical reaction with the ferromagnetic powder, the substance on the surface of the coating layer is measured by an X-ray photoelectron spectrometer to measure carbon / magnetic metal The ratio is determined, and the amount of change in the carbon / magnetic metal ratio before and after the treatment with the derivatizing reagent is within a predetermined range. When the magnetic layer is formed as a single-layer magnetic layer on the support and the magnetic material is an iron alloy, the amount of change in the carbon / magnetic metal ratio before and after the treatment with the derivatizing reagent is 0.25 or less. The above magnetic recording medium. When the magnetic layer is a multilayer magnetic layer formed on the lower coating layer formed on the support, and the magnetic substance is an iron alloy, the amount of change in the carbon / magnetic substance metal ratio before and after the treatment with the derivatizing reagent is zero. .
In the above magnetic recording medium, the number is preferably 5 or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, an unadsorbed additive is extracted and removed from a coated material having a coating layer containing at least an inorganic powder and a binder on a support with a nonpolar solvent such as n-hexane. After that, the coating material from which the unadsorbed additives have been removed is placed in a closed container, a derivatization reagent is added, and the derivative is formed by reacting with the adsorbed compound present in the coating layer. The binder in the coating layer is removed by a solvent that does not dissolve the binder. Then, the surface of the coating layer from which the unadsorbed additives have been removed by the solvent and the surface of the coating layer from which the compounds forming salts by adsorption or chemical reaction on the inorganic powder have been removed by derivatization treatment are exposed to X-rays. It is measured by an X-ray photoelectron spectroscopy analyzer, which is one of the surface analysis means, that is, an apparatus also called ESCA or XPS, and dissolved and removed as a derivative by reaction with a derivatizing reagent, and the compound before and after the removal is measured. Is what you do.
According to this method, it is possible to analyze the adsorbed compound present on the surface layer of the coating material or, in the case of the magnetic recording medium, the surface layer of the magnetic layer.

In the method of the present invention, for example, the coated material is immersed in a non-polar solvent such as n-hexane in a state of being coated on a support to extract and remove unadsorbed additives. A part of the sample from which the unadsorbed additive has been extracted and removed is taken out, placed in a sealable sample bottle, a derivatization reagent is added, and the mixture is allowed to react for an appropriate time to desorb the adsorbed compound as a derivative from the inorganic powder.
Then, the substance on the surface of the coating layer before and after the separation by the derivatization reagent is measured for the surface layer by surface analysis using an X-ray photoelectron spectrometer, and the amount of change in the measured value before and after the derivatization is adsorbed on the inorganic powder or The amount of the compound forming a salt by the chemical reaction is measured.

In the method of the present invention, examples of the derivatizing reagent include a silylating agent, an esterifying agent and an acylating agent, and it is particularly preferable to use a silylating agent. By using a silylating agent, a derivative can be formed by reacting with an organic phosphorus compound or a fatty acid metal salt having no active hydrogen, which has been considered impossible, so that the adsorbed organic phosphorus compound or fatty acid metal salt can be formed. Can be detected separately.

Further, by applying a silylating agent, it has become possible to directly analyze alcohols, phenols, amines, amides and the like as derivatives without extracting them. As described above, the reaction of the silylating agent can be applied to the case without active hydrogen, but the reaction of the silylating agent with active hydrogen is explained as follows.

[0012]

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Wherein X is a portion of the organic compound having active hydrogen except H, R is an alkyl group, Y is Cl, F
And the like. Examples of the silylating agent include N-trimethylsilylimidazole (TMSI), N, O-bis (trimethylsilyl) trifluoroacetamide (BS
TFA), N, O-bis (trimethylsilyl) acetamide (BSA), N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), N- (trimethylsilyl) dimethylamine (TMSDMA), N-
(Trimethylsilyl) diethylamine (TMS-DE
A), N-methyl-N-trimethylsilylacetamide (MTMSA), trimethylchlorosilane (TMC
S), hexamethylene disilazane (HMDS), N-methyl-N- (t-butyldimethylsilyl) -trifluoroacetamide (MTBSTFA) and the like. Particularly, a compound having TMS (trimethylsilyl group) is preferable.

Examples of the esterifying agent include boron trifluoride-methanol, boron trifluoride-n-propanol, boron trifluoride-isopropanol, boron trifluoride-n-butanol, dimethylformamide-dimethyl acetal (DMF -DMA), dimethylformamide-diethylacetal (DMF-DEA), dimethylformamide-di-n-propylacetal (DMF-D
NPA), dimethylformamide-di-n-butyl acetal (DMF-DNBA), hydrochloric acid-methanol, hydrochloric acid-n-butanol, phenyltrimethylammonium hydroxide (PTAH), tetramethylammonium hydroxide (TMAH), trimethyl (α, α, α-trifluoro-m-tolyl) ammonium hydroxide (TMTFAH), sodium methoxide-methanol, trimethylsilyldiazomethane (TMS-DAM) and the like.

As the acylating agent, trifluoroacetic anhydride (TFAA), heptafluorobutyric anhydride (HF
BA), pentafluoropropionic anhydride (PFP)
A), trifluoroacetylimidazole (TFA
I), heptafluorobutylyl imidazole (HFB)
I), pentafluoropropynyl imidazole (PFP
I), N-methylbis (trifluoroacetamide)
(MBTFA), pentafluorobenzyl bromide (PFBB) and the like. In this case, it is preferable to select a reagent that does not dissolve the binder or the support.

The analysis method of the present invention will be described by taking a magnetic layer of a magnetic recording medium as an example. The analysis of fatty acids that form salts by adsorption or chemical reaction on the magnetic substance and inorganic powder present on the surface layer of the coating type magnetic recording medium will be described. In a magnetic recording medium, when a ferromagnetic metal powder is used, many of the fatty acids added to the magnetic layer are bonded to the surface of the magnetic material by at least one of adsorption and chemical reaction,
It is difficult to completely extract with an organic solvent. Fatty acids bound to magnetic substances or other inorganic powders by adsorption or chemical reaction are removed by removing non-adsorbed fatty acids and other additives with a non-polar solvent, and then the magnetic substances are dissolved with an acid such as hydrochloric acid. It is obtained by extracting with a solvent. However, the total amount of the compound bonded to the inorganic powder by adsorption or the like can be measured, but the amount of the compound present in the surface of the magnetic layer and other inorganic powders which most affects the running characteristics of the magnetic recording medium can be measured. Fatty acids forming salts by adsorption or chemical reaction could not be quantified.

The inventors have further studied and extracted and removed the fatty acid ester and the unadsorbed fatty acid present on the surface of the magnetic layer with a non-polar organic solvent such as n-hexane. Fatty acids that have formed salts by adsorption or chemical reaction on solids and inorganic powders are dissolved as silylated products using a derivatizing reagent such as a silylating agent, and the surface material before and after the derivatization reaction is subjected to X-ray photoelectron spectroscopy. An object of the present invention is to provide a method of measuring by an analyzer and obtaining a difference between measured values before and after the derivatization reaction as an amount of fatty acid which forms a salt by adsorption or chemical reaction on the inorganic powder present on the surface of the magnetic layer.

Fatty acids do not have a specific element, but are structurally long-chain fatty acids. Attention is paid to the carbon element as an index of fatty acids that form salts by adsorption or chemical reaction. When iron alloy is used as the magnetic powder, the ratio of carbon / iron before and after the derivatization reaction should be determined to determine the compound bound by adsorption, etc. Can be. The amount of the fatty acid bound to the inorganic powder in the surface layer is determined by the above method, and the characteristics of the magnetic recording medium are measured at the same time. It can be confirmed that there is a change amount of carbon / iron, and a suitable fatty acid amount in the magnetic recording medium can be determined.

That is, fatty acids which form salts by adsorption or chemical reaction on the inorganic powder on the surface of the magnetic layer were determined, and the friction coefficient of the surface layer of the magnetic layer and the contamination of the head after running were examined. As a result, the change amount of C / Fe before and after derivatization, which is an index of the fatty acid present in the surface layer of the magnetic layer, ΔC /
It was found that the larger the Fe, the higher the friction coefficient.
Further, when the head was stained after running, it was confirmed that the stain was increased. This is considered to be because the presence of an excessive amount of fatty acid present in the surface layer of the magnetic layer and forming a salt by adsorption or chemical reaction with the magnetic substance and the inorganic powder increases the friction coefficient and causes head contamination.

For the smooth running of the magnetic recording medium, the amount of change before and after derivatization, which is an indicator of the fatty acid adsorbed and / or reacted on the surface of the magnetic layer, is determined by providing only the magnetic layer on the support. In a magnetic recording medium having a single magnetic layer, the amount of change ΔC / Fe before and after derivatization of the ratio of carbon to iron is preferably 0.25 or less, more preferably 0.2 or less. Further, in a multilayer magnetic recording medium in which a magnetic layer is formed on a lower nonmagnetic layer made of a nonmagnetic powder and a binder, ΔC / Fe is preferably 0.5 or less, more preferably 0.4 or less. It is.

In order to exhibit excellent characteristics not only immediately after manufacturing the magnetic recording medium but also after storage,
Even after storage, it is necessary that the amount of change in the ratio of carbon to iron before and after derivatization shows the same magnitude.

[0022]

The present invention will be described below with reference to examples. In the examples, "parts" indicates parts by weight. Example 1 [Preparation of Single Layer Magnetic Recording Medium] (Preparation of Coating Solution for Magnetic Layer) 1000 parts of ferromagnetic alloy powder (Hc1640 Oe, s130 emu / g, specific surface area 56 m ² / g, average major axis length 200 nm, needle shape Ratio 7.0, Fe: Co: Ni = 100: 5: 5) Carbon black (average particle size: 80 nm) 10 parts Polyvinyl chloride resin (MR-110 manufactured by Zeon Corporation) 108 parts Polyurethane resin (UR8300 manufactured by Toyobo Co., Ltd.) 41 parts Curing agent (Coronate 3040, manufactured by Nippon Polyurethane) 39 parts Abrasive (α-alumina average particle size 0.2 μm) 140 parts Phenylphosphonic acid 32 parts Stearic acid 8 parts Butyl stearate 14 parts Methyl ethyl ketone and cyclohexanone 1: 1 mixed solvent 200 parts were kneaded and dispersed, and a filter having an average pore size of 1 μm was used. Filtered, and prepare a coating solution for the magnetic layer.

(Preparation of Magnetic Tape) The magnetic paint was applied to the surface of a polyethylene terephthalate support having a thickness of 10 μm using an extrusion type coating head so that the thickness after drying was 3 μm. In the dried state, magnetic field orientation was performed with a 3000 Gauss magnet, and the following back coat coating solution was applied and dried so that the thickness after drying was 0.5 μm. Thereafter, a five-stage calendering process using a combination of a metal roll and a heat-resistant plastic roll (speed 100 m / m, linear pressure 300 kg / cm, temperature 9)
(0 ° C.). A video tape of the magnetic recording medium A was prepared by slitting to 1/2 inch width.

(Coating solution for backcoat layer) Carbon black (average particle size: 18 nm) 100 parts Nitrocellulose (RS1 / 2H manufactured by Daicel) 60 parts Polyurethane (N-2304 manufactured by Nippon Polyurethane) 60 parts Polyisocyanate (Nippon Polyurethanes) Coronate L) 20 parts Methyl ethyl ketone 1000 parts Toluene 1000 parts (Measurement of coating layer surface)
The sample A was cut out to a length of mm. Sample A was immersed in n-hexane at 20 ° C. for 30 minutes to extract and remove unadsorbed fatty acids and fatty acid esters. Then, 1/3 of sample A
And the surface of the magnetic layer is cut off with an X-ray photoelectron spectrometer (KR).
It was measured by AXIS-ULTRA manufactured by ATOS. The measurement was performed using an X-ray source: Al, an acceleration voltage: 12 kV, and a current:
The sample was irradiated with Kα ray lightened under the condition of 10 mA, and the sample was irradiated with a photoelectron emission angle of 90 °, a passing energy of 160 eV, and a detection range of 1 mm in diameter. After the hexane treatment, the ratio of carbon to iron on the sample surface and C _H / Fe were measured. did.

Next, ２ of the remaining sample A was placed in a sample bottle and sealed, and 10 ml of n-hexane and TMSI-H (HMDS: TMC) as a derivatizing reagent as a silylating agent were used.
S: pyridine mixture (manufactured by GL Sciences) 0.3
Then, the mixture was heated at 60 ° C. for 1 hour to perform a derivatization reaction. The sample A after the reaction was taken out, washed with ethanol and dried.

Next, the sample A after the derivatization reaction was measured again by an X-ray photoelectron spectrometer, and the ratio of carbon to iron on the sample surface after the treatment with the derivatization reagent, C _T / Fe
Was measured. Shown in Table 1 seeking the ratio of the change amount of the carbon to the front and rear of the iron derivatization process △ a C / Fe by _{△ C / Fe = C H /} Fe-C T / Fe. In addition, the coefficient of friction, surface roughness, head contamination, and the like of the video tape of the magnetic recording medium A evaluated by the following evaluation methods were measured and are shown in Table 1.

Example 2 A magnetic recording medium B was prepared in the same manner as in Example 1 except that stearic acid in the coating solution for the magnetic layer was changed to 12 parts. The layer surface and the characteristics as a magnetic recording medium were measured, and the results are shown in Table 1.

Comparative Example 1 A ferromagnetic alloy powder (Hc1545Oe,
s128 emu / g, specific surface area 48 m ² / g, average major axis length 200 nm, acicular ratio 8.0, Fe: Ni = 100:
A magnetic recording medium C was prepared in the same manner as in Example 1 except for the point 11), and the surface of the magnetic layer of the magnetic recording medium C and the characteristics as the magnetic recording medium were measured in the same manner as in Example 1. It is shown in Table 1.

Example 3 [Preparation of Multilayer Magnetic Recording Medium] (Preparation of Coating Solution for Magnetic Layer) Ferromagnetic Alloy Powder 1000 parts (Hc2200Oe σs143 emu / g Specific Surface Area 48 m ² / g Average Long Axis Length 85 nm Needle Ratio 6 0.0 Fe: Co = 100: 30 Sintering inhibitor Al compound, Y compound) Polyvinyl chloride polymer 100 parts (Polymerization degree 300 containing 1 × 10 ⁻⁴ eq / g of —SO ₃ Na group) Polyester polyurethane resin 50 Part (neopentyl glycol / caprolactone polyol / MDI = 0.9 / 2.6 / 1 (molar ratio) -containing SO ₃ Na group 1 × 10 ⁻⁴ eq / g) α-alumina (average particle diameter 0.16 μm) ) 40 parts carbon black (average particle diameter 50 nm, DBP oil absorption 90 ml / 100 g) 10 parts phenylphosphonic acid 30 parts butyl stearate 15 Part 5 parts of stearic acid 3000 parts of a 1: 1 mixed solvent of methyl ethyl ketone and cyclohexanone are kneaded and dispersed, 60 parts of polyisocyanate is added to the obtained dispersion, and 200 parts of a 1: 1 mixed solvent of methyl ethyl ketone and cyclohexanone are further added. The solution was filtered using a filter having an average pore diameter of 1 μm to prepare a coating solution for the magnetic layer.

(Preparation of Nonmagnetic Coating Solution for Lower Layer) Titanium oxide 850 parts (average particle size 0.035 μm, crystalline rutile, TiO ₂ content 90% or more, surface treatment layer; alumina, BET specific surface area 35 to 42 m ² / G, true specific gravity 4.1, pH 6.5-8.0) was pulverized with an open kneader for 10 minutes, and then 75 parts of a vinyl chloride copolymer resin (vinyl chloride / vinyl acetate / glycidyl methacrylate = 86/9/5) Copolymer: SO ₃ Na = 6 × 10 ⁻⁵ eq / g, epoxy = 10 ⁻³ eq / g, Mw 30,000) Polyurethane resin (UR8300 manufactured by Toyobo Co., Ltd.) 100 parts Phenylphosphonic acid 30 parts Cyclohexanone 600 parts And knead for 60 minutes, then add methyl ethyl ketone / cyclohexanone = 6/4 2000 parts and disperse in a sand mill for 120 minutes It was. To this, 20 parts of butyl stearate, 10 parts of stearic acid, and 500 parts of methyl ethyl ketone were added, and the mixture was further stirred and mixed for 20 minutes. Then, the mixture was filtered using a filter having an average pore diameter of 1 μm to prepare a nonmagnetic coating liquid for a lower layer.

(Preparation of Magnetic Tape) A non-magnetic coating solution for a lower layer was formed to a thickness of 2.0 μm on the surface of a polyethylene terephthalate support having a thickness of 10 μm. Is 0.1 μm,
Simultaneous multilayer coating was performed using a reverse roll. The non-magnetic support coated with the magnetic coating solution is subjected to magnetic field orientation with a 3000 Gauss magnet in a state where the magnetic coating solution is not dried, and after drying, the metal roll-metal roll-metal roll-metal roll-metal roll -Metal roll-Calendar treatment by combination of metal roll (speed 100m / m, linear pressure 30
0kg / cm, temperature 90 ° C) and 6.35mm
The resultant was cut into a width to produce a video tape of the magnetic recording medium C.

(Measurement of Surface of Coating Layer) The prepared magnetic recording medium D was cut into a 100 mm long sample D. The coating layer surface of the sample D was measured in the same manner as in the measurement method described in Example 1. In addition, the friction coefficient, surface roughness, head contamination, and the like of the video tape of the magnetic recording medium D, which were evaluated by the following evaluation methods, were measured and are shown in Table 2.

Example 4 A magnetic recording medium E was prepared in the same manner as in Example 3, except that the stearic acid in the coating solution for the magnetic layer was changed to 10 parts. The layer surface and characteristics as a magnetic recording medium were measured, and the results are shown in Table 2.

Comparative Example 2 A magnetic recording medium F was prepared in the same manner as in Example 4, except that α-iron oxide was used as the titanium oxide in the coating solution for the magnetic layer. The characteristics of the magnetic layer surface and the magnetic recording medium were measured, and the results are shown in Table 1.

[0035]

Table 1 ΔC / Fe Coefficient of friction Surface roughness (nm) Head dirt Example 1 0.18 0.22 6 Good Example 2 0.22 0.27 6 Slight dirt Comparative example 1 0.29 0. 336 Large dirt

[0036]

Table 2 ΔC / Fe Friction coefficient Surface roughness (nm) Head dirt Example 3 0.29 0.23 6 Good Example 4 0.35 0.306 Slight dirt Comparative example 2 0.60 546 6 Sticky

(Method for Evaluating Characteristics) a) Coefficient of friction The produced video tape and stainless steel rod (SUS420)
J) at a tension (T1) of 50 g and a winding angle of 180 °
And the tension (T2) required for running the video tape at a speed of 3.0 cm / s was measured. From the obtained T1 and T2, the friction coefficient (μ) of the video tape was determined by the following calculation formula. μ = 1 / π × ln (T2 / T1) The friction coefficient was measured under the conditions of 23 ° C. and 70 RH, and the measured value in the first pass was adopted. b) Surface roughness: The center line average roughness was expressed as Ra in nm using a digital optical profilometer (manufactured by WYKO) at a cutoff of 0.25 mm. c) Head dirt 1 20 ° C. 50% using a digital video tape recorder (Digital Betacam DVW-A500 type made by Sony)
In a RH environment, the head was continuously run for 2000 m, and the state of head contamination after running was evaluated. d) Head dirt 2 Digital video tape recorder (Matsushita Electric NV-B)
Using J1), the video head was run for 50 m and the stain on the video head was observed.

[0038]

According to the present invention, a composition comprising a ferromagnetic powder and a binder is adsorbed on a ferromagnetic powder of a magnetic layer of a magnetic recording medium formed on a support or a salt is formed by a chemical reaction. The compound that cannot be removed is desorbed as a derivative, and the elemental intensity of the surface before and after the derivatization reaction is measured by an X-ray photoelectron spectrometer, whereby the inorganic powder present on the surface layer that correlates with properties such as running properties is measured. And an index of the amount of the compound forming a salt by adsorption or chemical reaction with a magnetic substance.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Mikio Ohno 2-12-1, Ogimachi, Odawara-shi, Kanagawa Prefecture F-Film Co., Ltd. F-term (reference) 2G001 AA01 BA08 CA03 JA12 KA01 LA20 MA04 NA03 NA17 RA01 RA02 RA03 5D006 BA19 FA00 5D112 AA05 JJ06

Claims (7)

[Claims] 1. A method for analyzing a compound in which a salt is formed by adsorption or chemical reaction on an inorganic powder on a surface of a coating layer provided with a coating layer comprising at least an inorganic powder and a binder on a support. After the non-adsorbed substance is extracted and removed by the solvent from the support provided with
After measuring by a X-ray photoelectron spectrometer, the derivatizing reagent is added and the adsorbed compound on the surface of the inorganic powder is reacted and removed, and then the substance on the coating layer surface is measured by an X-ray photoelectron spectrometer, and the A method for analyzing an adsorbed compound on the surface of an inorganic powder-containing coating layer, comprising analyzing a compound forming a salt by adsorption or chemical reaction from a difference between measured values before and after the treatment. 2. The method according to claim 1, wherein the coating layer is a magnetic layer of a magnetic recording medium containing a ferromagnetic powder. 3. The method of claim 1, wherein the derivatizing reagent is a silylating agent. 4. The method according to claim 1, wherein the compound adsorbed on the inorganic powder is a fatty acid. 5. In a magnetic recording medium having a magnetic layer containing a magnetic powder and a binder formed on a support, a solvent is allowed to act on the magnetic recording medium to extract and remove unadsorbed substances.
After adding a derivatizing reagent and reacting and removing the compound which forms a salt by adsorption or chemical reaction with the inorganic powder, the substance on the surface of the coating layer is measured with an X-ray photoelectron spectrometer to measure the carbon / magnetic material The ratio is determined, then a derivatizing reagent is added, and the compound forming a salt by adsorption or chemical reaction on the ferromagnetic powder is removed by reaction, and then the substance on the surface of the coating layer is measured by an X-ray photoelectron spectrometer. A magnetic recording medium wherein a carbon / magnetic metal ratio is determined, and a change amount of the carbon / magnetic metal ratio before and after treatment with a derivatizing reagent is within a predetermined range. 6. The method according to claim 1, wherein the magnetic layer is formed as a single-layer magnetic layer on the support, and when the magnetic substance is an iron alloy, the amount of change in the carbon / magnetic substance metal ratio before and after the treatment with the derivatizing reagent is zero. 6. The magnetic recording medium according to claim 5, wherein the ratio is not more than .25. 7. A carbon / magnetic metal ratio before and after treatment with a derivatizing reagent when the magnetic layer is a multilayer magnetic layer formed on a lower coating layer formed on a support and the magnetic substance is an iron alloy. 6. The magnetic recording medium according to claim 5, wherein the amount of change is 0.5 or less.