JPH11296848A - Method for analyzing fatty acid and/or fatty acid ester in magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute to the control of the adding quantity of fatty acid, etc., deeply related with abrasion and friction characteristic by separating and analyzing a sample obtained by thermal extraction by a gas chromatograph and mass spectrometer so as to execute qualitative/quantative analysis so as to unnecessitate preprocessing by organic solvent to make rapidly analyzable. SOLUTION: Fatty acid and/or fatty acid ester included in a magnetic recording medium constituting layer are thermally extracted at a temperature of 380 to 450 deg.C and separated by a gas chromatograph with steam pressure higher than a fixed limit to give qualitative analysis to the separated matter by a mass spectrometer. A compound is specified from a mass spectrum ranging a wide mass range. In order to eliminate the influence of other components on the other hand, selective ion measuring for detecting as a peak for the quantative of only characteristic mass ion to execute quantative from a peak area by an absolute analytical curve method, etc. Thus, the preprocessing of the sample is also eliminated without using the organic solvent to execute qualitative and quantative analysis with a small amount of the sample, speedily and while considering environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic recording medium (particularly, a magnetic layer or back coat formed by dispersing a ferromagnetic powder or a non-magnetic powder on a non-magnetic support together with a fatty acid and a fatty acid ester in a binder). Magnetic tape having a layer,
The present invention relates to a method for analyzing fatty acids and / or fatty acid esters in a magnetic recording medium such as a magnetic disk (particularly, a qualitative / quantitative analysis method).

[0002]

2. Description of the Related Art When a coating type magnetic recording medium, for example, a magnetic tape is slid for a long time or many times over a recording / reproducing head or a fixed guide, a magnetic powder, an additive or a binder is dropped. A so-called powder drop may occur, and these fallouts may reattach to the magnetic layer of the magnetic tape. In this way, if the fallout adheres to the magnetic layer of the magnetic tape,
There is a possibility that the recording / reproducing characteristics such as dropout and head clog may be deteriorated.

[0003] The problem of powder falling off from the magnetic tape is closely related to the friction and wear characteristics of the magnetic head and the fixed guide. To improve the friction and wear characteristics, the magnetic layer and the back layer are coated with myristic acid. Or a lubricant such as fatty acid such as butyl stearate or the like.

[0004] Therefore, qualitative and quantitative analysis of fatty acids and fatty acid esters in the magnetic layer and / or the back layer is important in studying the improvement of friction and wear characteristics.

[0005]

Heretofore, the qualitative and quantitative analysis of fatty acids and fatty acid esters in a magnetic recording medium has been described.
A method of extracting with an organic solvent and analyzing with an organic analyzer such as an infrared spectrophotometer or a liquid chromatograph is generally known. However, in the conventional method, there are problems that a pretreatment of the sample such as extraction, dissolution, concentration, etc. is required, and that a large amount of an organic solvent is used, which adversely affects the environment.

An object of the present invention is to eliminate the pretreatment of a sample such as extraction, dissolution, concentration and the like with an organic solvent which was required in the conventional method, to carry out the method quickly without using a large amount of an organic solvent, and to reduce environmental problems. It is an object of the present invention to provide a qualitative and quantitative analysis method of fatty acids and fatty acid esters in a magnetic recording medium in consideration of the above.

[0007]

That is, the present invention provides a method for analyzing fatty acids and / or fatty acid esters contained in a magnetic recording medium constituting layer (particularly, a magnetic layer or a back layer). A step of heat extraction, and a step of separating the obtained heat extract by gas chromatography,
A magnetic recording method comprising a step of subjecting the separated product to a mass spectrometer to obtain a mass spectrum for qualitative analysis, and more preferably a step of quantifying the fatty acid and / or fatty acid ester from the peak area of the mass spectrum. The present invention relates to a method for analyzing fatty acids and / or fatty acid esters in a medium (hereinafter, referred to as an analysis method of the present invention).

According to the analysis method of the present invention, the magnetic recording medium is heat-extracted, the obtained heat extract is separated by gas chromatography, and qualitative analysis is performed by mass spectrum using a mass spectrometer as a detector. By performing quantification from the peak area, qualitative / quantitative analysis of fatty acids and fatty acid esters in the magnetic recording medium can be performed quickly and with consideration for the environment. In particular, it is very significant that the pretreatment can be substantially omitted without using an organic solvent.

According to the analysis method of the present invention, the magnetic layer and / or
Alternatively, qualitative and quantitative analysis of fatty acids and fatty acid esters in the back layer is performed, and based on the analysis results, the amount of fatty acids and the like is controlled during the preparation of magnetic paints and the like, and the amount of additives for improving the friction property is improved. Can be set.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed procedure of a method for qualitatively and quantitatively analyzing fatty acids and fatty acid esters in a magnetic recording medium based on the analysis method of the present invention will be described below.

First, an apparatus used for heat extraction of a magnetic recording medium becomes a gas having a vapor pressure exceeding a certain limit at a set column temperature when the heat extract is sent to a gas chromatograph. Any temperature may be used, but the temperature of the heat extraction must be in the range of 380 ° C to 450 ° C. The gas chromatograph is not particularly limited as long as these heat extracts are sufficiently separated. The mass spectrometer is not limited as long as the separated thermal extract is detectable.

In the above qualitative analysis, mass ions are detected over a wide mass range, and the compound is specified from the obtained mass spectrum.

In the above-described quantitative analysis, in order to eliminate the influence of other components, a selected ion measurement (Selected ion measurement) in which only a unique mass ion is detected as a peak for quantification is performed.
IonMonitoring), and quantification is performed from the peak area using the absolute calibration curve method or the internal standard method. At this time, a stable ion with little variation is selected as the mass ion.

In the analysis method of the present invention, the following are exemplified as fatty acids and fatty acid esters to be analyzed.
Fatty acids include lauric, myristic, oleic, palmitic and stearic acids. Further, as the fatty acid ester, heptyl laurate, heptyl myristate, heptyl palmitate, heptyl stearate, butyl laurate, butyl myristate, butyl oleate, butyl palmitate, butyl stearate,
Methyl myristate, methyl oleate, methyl palmitate, methyl stearate, octyl myristate,
Octyl palmitate, octyl stearate and the like can be mentioned.

These fatty acids and fatty acid esters are contained as a lubricant in the constituent layers of the magnetic recording medium, particularly in the magnetic layer and the back layer.

In the magnetic layer, additional components such as a magnetic powder and an abrasive are dispersed in a binder.

Examples of the magnetic powder include Fe and C.
o, powder of a single ferromagnetic metal such as Ni, or Fe-C
An alloy powder such as o, Fe-Ni, Co-Ni, or an alloy powder composed of three or more metals can be used. Furthermore, in order to improve these various characteristics,
Al, Si, Pb, Ti, Cr, Mn, Cu, Y, M
It may contain o, Sn, Ba, Zn, and the like.

Further, oxide magnetic powder can be used as the magnetic powder, for example, γ-Fe ₂ O
₃ , Co-containing γ-Fe ₂ O ₃ , Co-coated γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co
Fe ₃ O ₄ , Co-coated Fe ₃ O ₄ , CrO _{2, and the} like. Also, hexagonal ferrites such as barium ferrite, iron nitride, and the like can be used.

As the abrasive, alumina (α
-Al ₂ O ₃ , β-Al ₂ O ₃ , γ-Al ₂ O ₃ , δ-Al ₂ O ₃ , ζ-A
l ₂ O ₃ , η-Al ₂ O ₃ , θ-Al ₂ O ₃ , κ-Al ₂ O ₃ , χ-Al ₂
O ₃ , ρ-Al ₂ O ₃ etc.), alumina hydrate, alumina silicate, other silicates, silicon carbide, boron carbide, other carbides, chromium oxide, iron oxide (α-iron oxide), etc. Non-magnetic oxide, boron nitride, titanium oxide, silicon oxide, silicon nitride, zirconium oxide, zinc oxide, cerium oxide,
Magnesium oxide, boron nitride and the like can be used.

The binder is not particularly limited as long as it is used in ordinary magnetic coatings (particularly magnetic coatings for magnetic recording media).

For example, polyester, polycarbonate, or polyester-based polyurethane resin, polyester resin, vinyl chloride-based copolymer, cellulose derivative, phenoxy resin, acrylate-based copolymer,
Examples thereof include vinylidene chloride-based copolymers and styrene-butadiene-based copolymers.

These binders have the following functional groups (polar groups) in some or all of the binders used in order to obtain good dispersibility of magnetic powders and abrasives. You may.

For example, -COOM, -SO ₃ M, -O-
_{SO 3 M, -P = O (} OM) 2, -O-P = O (OM)
_{2, -NR 4 X, -NR 2} , -SH ( where, M is, H,
Li, Na, K or an alkyl group, and R represents an alkyl group or H or X represents a halogen atom).

One or more of these functional groups and binders may be contained.

Solvents used for mixing and dispersing the magnetic powder or abrasive with a binder to form a coating include ketones such as methyl ethyl ketone and cyclohexanone, alcohols such as methanol and isopropyl alcohol, ethyl acetate and acetic acid. Esters such as butyl, aromatic hydrocarbons such as toluene and benzene, chlorinated hydrocarbons such as carbon tetrachloride and chloroform, and ethers such as dioxane and diethylene glycol monoethyl ether.

In addition, known additives such as a curing agent and a dispersant may be added.

As a curing agent added for the purpose of forming a crosslinked structure in the binder and improving the strength of the magnetic coating film, for example, a polyisocyanate-based curing agent is preferable. Isocyanates such as 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, isophorone diisocyanate, and adducts of these isocyanates with polyhydric alcohols such as trimethylolpropane, or condensation products of isocyanates. Can be used.

In addition, carbon black or the like can be added for the purpose of obtaining an antistatic effect, a light-shielding effect, a friction reducing effect, and the like as long as the electromagnetic conversion characteristics and running durability are not reduced. In addition, various known additives can be added for the purpose of dispersing effect, cross-linking promoting effect, plasticizing effect and the like.

Examples of the nonmagnetic support forming the magnetic layer and the like include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate;
Polyolefins such as polypropylene; cellulose derivatives such as cellulose triacetate and cellulose diacetate; and plastics such as polyamide and polycarbonate. In addition, metals such as Cu, Al, and Zn, glass, boron nitride, and ceramics such as Si carbide can also be used.

On the surface of the nonmagnetic support, an intermediate layer or an undercoat layer may be provided to improve the adhesiveness of the magnetic layer.

On the surface of the non-magnetic support opposite to the magnetic layer, a non-magnetic powder (for example, silica or carbon black) and a binder (as described above) are provided to improve the running property of the medium. May be provided).

FIG. 7 is a schematic sectional view of an essential part showing an example (magnetic tape for video) of a magnetic recording medium manufactured according to the method for manufacturing a magnetic recording medium of the present invention.

That is, on one surface of the nonmagnetic support 11,
There is a magnetic layer 12 containing the magnetic powder, the abrasive, the binder and the like. Further, a back coat layer 13 mainly composed of a non-magnetic powder and a binder may be provided on the other surface, as indicated by a chain line in the figure.

Such a magnetic recording medium is prepared by applying a magnetic paint comprising the magnetic powder, the lubricant, the binder and the like onto the non-magnetic support 11 by means of a die coater, a gravure roll or the like. After a coating film is formed, the magnetic layer 12 is formed through a magnetic field orientation treatment, a drying treatment, a calendering treatment, and the like, and after being cut into a predetermined shape, a magnetic tape or a magnetic disk is formed.

For the purpose of controlling the surface properties of the magnetic layer, for example, a non-magnetic powder (eg, carbon black, calcium carbonate, titanium oxide, etc.) and a binder are interposed between the magnetic layer and the non-magnetic support. When manufacturing a multilayer coating type magnetic recording medium provided with a non-magnetic layer of the following, the magnetic layer of the magnetic recording medium may be formed based on the manufacturing method of the present invention.

The magnetic recording medium has a tape shape,
Any shape generally used as a magnetic recording medium, such as a film, a sheet, a card, a disk, and a drum, can be adopted.

[0037]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to the following examples.

Each component of the magnetic paint having the composition shown below was kneaded in a continuous kneader, and then dispersed using a sand mill.
Further, 4 parts by weight of polyisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L) and 1 part by weight of myristic acid were added, and the mixture was filtered through a filter having an average diameter of 3 μm,
It was a magnetic paint.

<Magnetic Coating Composition><Magnetic Layer Coating Composition> 100 parts by weight of Co-modified γ-Fe ₂ O ₃ (specific surface area by BET method: 45 m ² / g) Nitrocellulose (manufactured by Asahi Kasei Corporation: trade name NC-1 / 2 H) 8 parts by weight Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 6 parts by weight (manufactured by UCC: Vinylite VAGH) Polyurethane resin (manufactured by Nippon Polyurethane Co., Ltd .: N-2304) 8 parts by weight α-Al ₂ O ₃ 3 parts by weight Polyisocyanate (manufactured by Nippon Polyurethane Co .: trade name Coronate L) 4 parts by weight Myristic acid or butyl stearate (described later) Methyl ethyl ketone 100 parts by weight Toluene 100 parts by weight Cyclohexanone 50 parts by weight

Further, among the components of the coating material for forming the back coat layer shown below, each component except for the polyisocyanate was dispersed using a sand mill, and then 4 parts of polyisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added.
The mixture was filtered by a filter having an average diameter of 3 μm to obtain a coating material for forming a back coat layer.

<Coating for forming back coat layer> Carbon black (manufactured by CABOT: trade name BP-I) 100 parts by weight Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 25 parts by weight (manufactured by UCC: vinylite VAGH) 25% by weight of polyurethane resin (manufactured by Nippon Polyurethane Co., Ltd .: N-2304) 4 parts by weight of polyisocyanate (manufactured by Nippon Polyurethane Co., Ltd .: coronate L) Myristic acid or heptyl stearate (described later) 150 parts by weight of methyl ethyl ketone Parts cyclohexanone 100 parts by weight

The magnetic paint was applied to a polyethylene terephthalate film (thickness: 11 μm) to a thickness of 3.5 μm, calendered and dried to form a magnetic layer. Further, if necessary, the above-mentioned coating material for forming a back coat was applied to the surface of the polyethylene terephthalate film opposite to the magnetic layer at a thickness of 0.8 μm, and dried to produce a magnetic recording medium having a structure as shown in FIG. . Then, it was cut into 1 inch width and taped.

The magnetic tape thus obtained was subjected to heat extraction, separation by gas chromatography, and qualitative / quantitative analysis by a mass spectrometer under the following conditions.

Pyrolysis apparatus: Curie point pyrolyzer of JHP-3S type (manufactured by Nippon Kagaku Kogyo Co., Ltd.) Gas chromatograph and detector: QP-2000GF gas chromatograph mass spectrometer (manufactured by Shimadzu Corporation) Column: DB-5 ms (J & W) 0 .25 μm (film thickness)
× 0.25 mm (inner diameter) × 30 m (length) Carrier gas and flow rate: He 1 ml / min Heat extraction temperature: 423 ° C. (gas chromatography connection pipe 300 ° C.) Heat extraction time: 1 minute Sample injection port temperature: 250 ° C. Column rise Temperature condition: 50 ° C (hold for 2 minutes) → 10 ° C / min
→ 280 ° C (hold for 5 minutes) Split ratio: 1:40 Sample area: 25.4 mm x 10 mm

<Example 1> In this example, a qualitative analysis was performed on a magnetic tape coated with myristic acid (molecular weight: 228) added to a magnetic layer under the above-described conditions.

In FIG. 1, the peak indicated by a is identified as myristic acid from the mass spectrum shown in FIG. 2, which indicates that the qualitative analysis using the analysis method of the present invention is effective.

Example 2 In this example, qualitative analysis was performed on a magnetic tape coated with the addition of myristic acid (molecular weight: 228) and butyl stearate (molecular weight: 341; including butyl palmitate) to the magnetic layer. It was done.

In FIG. 3, the peaks indicated by b, c and d are identified as myristic acid, butyl palmitate and butyl stearate from the mass spectra shown in FIGS. 4, 5 and 6, and the analysis method of the present invention was carried out. The qualitative analysis used is found to be effective.

Example 3 In this example, the back layer was coated with myristic acid at 0.31 mg / m ² , 0.63 mg / m ² ,
0.94 mg / m ² , 39 mg of heptyl stearate
/ M ² , 79 mg / m ² , and 118 mg / m ² were subjected to quantitative analysis under the conditions described above for the applied magnetic tape. Myristic acid was selected from 73 mass ions, and heptyl stearate was selected from 267 mass ions, and the quantitative results obtained by the absolute calibration curve method are shown in Table 1 below.

<Comparative Example 1> In this comparative example, myristic acid was added to the back layer in an amount of 0.31 mg / m ² and 0.63 mg / m ² .
m ² , 0.94 mg / m ² , heptyl stearate 3
About magnetic tape (same as Example 3) coated with 9 mg / m ² , 79 mg / m ² and 118 mg / m ² , n
-Extracted with hexane for 5 minutes and subjected to quantitative analysis by liquid chromatography. The results of quantification determined by the absolute calibration curve method are shown in Table 1 below.

[0051]

As is evident from Table 1, the quantitative value obtained by using the analysis method of the present invention shows a value almost consistent with the coating amount, and also coincides with Comparative Example 1. Quantitative analysis using the method proves to be effective.

[0053]

According to the analysis method of the present invention, the magnetic recording medium is thermally extracted, the obtained heat extract is separated by gas chromatography, and qualitative analysis is performed by mass spectrum using a mass spectrometer as a detector. Because organic solvent such as n-hexane should be hardly used. The amount of the sample should be about 1/3000 of that of the normal extraction method. Pretreatment (extraction operation, dissolution, etc.) of the sample is not required. It is possible to quickly and qualitatively and quantitatively analyze fatty acids and fatty acid esters in a magnetic recording medium while taking the environment into consideration.

[Brief description of the drawings]

FIG. 1 is a pyrogram diagram of a magnetic recording medium coated with myristic acid.

FIG. 2 is a mass spectrum diagram of a peak a shown in FIG.

FIG. 3 is a pyrogram of a magnetic recording medium coated with myristic acid and butyl stearate.

FIG. 4 is a mass spectrum diagram of a peak b shown in FIG.

5 is a mass spectrum diagram of a peak c shown in FIG.

FIG. 6 is a mass spectrum diagram of a peak d shown in FIG.

FIG. 7 is a schematic sectional view of an example of the magnetic recording medium of the present invention.

[Explanation of symbols]

11: Non-magnetic support, 12: Magnetic layer, 13: Back coat layer

Claims (4)

[Claims] When analyzing fatty acids and / or fatty acid esters contained in a magnetic recording medium constituent layer, a step of subjecting the magnetic recording medium constituent layer to heat extraction processing, and separating the obtained heat extract by gas chromatography. A method for analyzing fatty acids and / or fatty acid esters in a magnetic recording medium, comprising: performing a qualitative analysis by obtaining a mass spectrum of the separated product using a mass spectrometer. 2. The analysis method according to claim 1, further comprising a step of quantifying the fatty acid and / or fatty acid ester from the peak area of the mass spectrum. 3. The analysis method according to claim 1, wherein the fatty acid and the fatty acid ester are qualitatively and quantitatively analyzed without using an organic solvent. 4. The analysis method according to claim 1, wherein the fatty acid and / or fatty acid ester contained in the magnetic layer and / or the back layer is qualitatively and quantitatively analyzed.