JP2646018B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium having good heat resistance and excellent running durability at high temperatures.

[Conventional technology]

A magnetic recording medium is usually prepared by applying a magnetic paint comprising a magnetic powder, a binder component, an organic solvent and other necessary components on a substrate such as a polyester film and drying. At this time, a binder component that is excellent in dispersibility of a magnetic powder, can provide a magnetic recording medium with selected electromagnetic conversion characteristics such as high sensitivity, and can be selected for durability is desired.

For this reason, various research and developments have been made on binder resins, for example, by introducing a hydrophilic polar group such as a carboxyl group, a sulfone group, or a phosphoric acid into a vinyl chloride resin or the like, thereby dispersing the magnetic powder. Attempts have been made to improve. [Journal of the Adhesion Society of Japan Vol. 17, p. 155 (198
1), IEEE Transaction Magnetic MAG-20 P-745 (198
1), JP-A-61-133012, JP-A-61-133013, JP-A-57-4227, JP-A-54-46514, JP-A-54-46515
No., JP-A-54-46516, JP-A-54-46517, JP-A-54-46517
-46518, JP-A-54-46519, JP-A-54-84707,
[Problems to be Solved by the Invention] However, these binder resins such as vinyl chloride resins into which a hydrophilic polar group has been introduced are made of magnetic powder. Despite its excellent dispersibility, when placed at high temperatures, the catalytic action of these hydrophilic polar groups causes dehydration or dehydrochlorination, which causes thermal decomposition, which is a problem in running durability at high temperatures. was there.

[Means for Solving the Problems] The present invention has been made as a result of various studies in view of the present situation, and has a binder resin having a salt moiety obtained by a reaction between phosphoric acid and an amino acid in a side chain of a molecule. By using this, the catalytic action of the hydrophilic polar group is suppressed, the binder resin is prevented from being thermally decomposed, and the heat resistance and running durability at high temperatures are sufficiently improved.

The amine used for obtaining the composite resin in the present invention includes a primary amine, a secondary amine, a tertiary amine and a general formula (Where R ₁ , R ₂ , R ₃ , and R ₄ are H or an alkyl group having 1 to 20 carbon atoms, p, q, and r are integers of 1 to 10, and x is 0 or 1). Polyamines, amino alcohols, amino ethers, carboxylic esters having an amino group, etc. are all used as suitable ones.

The primary amine is represented by the general formula: RNH ₂ (where R is a linear or branched hydrocarbon group having 1 to 20 carbon atoms, or a cyclic hydrocarbon group forming a 3 to 10-membered ring) ) Is preferably used, and specific examples thereof include:
For example, linear aliphatic amines such as myristylamine, stearylamine, caprylamine, and butylamine; aliphatic amines having a branched structure in the molecule such as isopropylamine, isobutylamine, and t-butylamine; and aliphatic amines such as acrylamine Examples include alicyclic amines such as unsaturated amines, cyclopentylamines and cyclohexylamines, and aromatic amines such as aniline.

Further, as the secondary amine, a general formula, R ₁ R ₂ NH (where R ₁ and R ₂ are a linear or branched hydrocarbon group having 2 to 20 carbon atoms, or a 3- to 10-membered ring) An amine represented by a hydrocarbon group is preferably used, and specific examples thereof include linear aliphatic amines such as diethylamine and dimethylamine, and fatty acids having a branched structure in the molecule such as diisopropylamine. Aliphatic amines such as aliphatic amines and diallylamine; alicyclic amines such as dicyclohexylamine; and aromatic amines such as methylaniline and ethylaniline.

Further, as the tertiary amine, a compound represented by the general formula: R ₁ R ₂ R ₃ N
(However, R ₁ , R ₂ and R ₃ are a linear or branched hydrocarbon group having 3 to 20 carbon atoms or a cyclic hydrocarbon group forming a 3 to 10-membered ring.) Preferred examples thereof include linear aliphatic amines such as triethylamine and trimethylamine, aliphatic amines having a branched structure in the molecule such as diisopropylethylamine, and aliphatic amines such as triacrylamine. Saturated amines, alicyclic amines such as N, N-diethylcyclohexylamine, dimethylaniline, diethylaniline,
And aromatic amines such as triphenylamine.

Examples of the polyamine represented by the general formula include ethylenediamine, hexamethylenediamine,
Sym-dimethylethylenediamine, N, N, N ', N'-tetramethylethylenediamine, etc.Polyamine having an amino group at the end of the molecular chain, diethylenetriamine, tetraethylenepentamine, etc. Polyamines and the like are preferably used.

Further, as the amino alcohol, a general formula HO- (R _x ) _s -NH ₂ (where s is an integer of 1 to 30, R _X is a linear or branched hydrocarbon group having 1 to 20 carbon atoms, Alternatively, it is a cyclic hydrocarbon group forming a 3- to 10-membered ring, and the linear or branched hydrocarbon group having 1 to 20 carbon atoms may have a hydroxyl group or an amino group in the group. Or HO- (R _x ) _s -NHR (where s is an integer of 1 to 30; R _X and R are 1 to 20 carbon atoms)
Is a linear or branched hydrocarbon group, or a cyclic hydrocarbon group forming a 3 to 10-membered ring, wherein the linear or branched hydrocarbon group having 1 to 20 carbon atoms is May have a hydroxyl group or an amino group. Or HO- (R _x ) _s -NR ₁ R ₂ (where s is an integer of 1 to 30, and R _X , R ₁ and R _{2 each} have 1 carbon atom)
~ 20 linear or branched hydrocarbon groups, or 3 ~
A cyclic hydrocarbon group forming a 10-membered ring, having 1 to 1 carbon atoms.
The 20 linear or branched hydrocarbon groups may have a hydroxyl group or an amino group in the group. ) Is preferably used, and specific examples thereof include, for example, monoethanolamine, isopropanolamine, 2-amino-1-butanol,
-(Methylamino) -ethanol, diethanolamine, N, N-dimethylethanolamine, N-methyldiethanolamine, 2- (2-hydroxyethylamino)
Examples include ethanolamine and triethanolamine.

Examples of the amino ether include straight-chain primary amino ethers such as 2-methoxyethylamine and the like, and primary amino ethers having a branched structure such as aminoether and 2-methoxyisopropylamine, and direct amino acids such as 2-methoxytylethylamine. Linear secondary amino ether, 2-
Secondary amino ethers having a branched structure such as methoxyethyl isopropylamine and tertiary amino ethers such as 2- (dimethylamino) ethyl ether are preferably used.

Further, as the carboxylic acid ester having an amino group, those having a primary, secondary or tertiary amino group in the molecule are all preferably used. -N, N-dimethylaminopropionate ethyl, N, N-dimethylglycine ethyl ester, N, N-dimethylalanine ethyl ester, propionic acid 2-N, N-dimethylaminoethyl ester, propionic acid 3-N, N- And dimethylaminopropyl ester.

Each of these amines has basicity, and -PO (OH)
_When reacted with a binder resin having an acidic group consisting of a phosphoric acid group such as ₂ , -OPO (OH) ₂ , all or a part of these acidic groups are neutralized to form a salt to sufficiently suppress the catalytic action. Even at high temperatures, dehydration reaction and dehydrochlorination reaction are prevented, and thermal decomposition of the binder resin is favorably suppressed.
Furthermore, in the case of amino alcohol, the reaction with the isocyanate compound is promoted, and a coating film having a high crosslinking density can be obtained. Thus, the heat resistance of the magnetic layer is sufficiently improved, and the running durability at a high temperature is sufficiently improved.

The binder resin of the present invention generally comprises such an amine, for example, of the general formula (However, l + m + n is 1 to 60 mol%, m + n is 0.5 to 2
0% and n is 0.5 to 5.0 mol%. ) Represented by -OPO _{(OH) 2} group-containing vinyl chloride resin, also -PO _{(OH) 2} group-containing polyurethane resins, -OPO (OH)
_2- group-containing phenoxy resin, -OPO (OH) _2- group-containing polyester resin, -OPO (OH) _2- group-containing polycarbonate resin, -OPO (OH) _2- group-containing cellulose resin, -OPO (OH) ₂
It can be easily obtained by allowing a group-containing butyral resin or the like to coexist in an organic solvent at room temperature or at a high temperature for reaction.

All of these binder resins thus obtained have good affinity with magnetic powder, excellent dispersibility, and excellent mechanical properties and electromagnetic conversion properties. Is sufficiently suppressed, the heat resistance is also improved, and the running durability at high temperatures is sufficiently improved. Furthermore, when used in combination with an isocyanate compound, the crosslinking reaction is accelerated, and a coating film having further excellent running durability is obtained.

The magnetic recording of the present invention may be manufactured according to a conventional method.For example, a magnetic powder containing a magnetic powder, a binder resin of the present invention, an organic solvent and other necessary components may be formed on a substrate such as a polyester film. The paint may be applied by any means such as spraying or roll coating and dried.

Here, as the magnetic powder used, for example, γ
-Fe ₂ O ₃ powder, Fe ₃ O ₄ powder, γ-Fe ₂ O ₃ powder and Fe ₃ O ₄ powder of the intermediate oxide powders, Co-containing γ-Fe ₂ O ₃ powder, Co-containing Fe ₃ O ₄ powder, In addition to CrO ₂ powder, Fe powder, Co powder, Ni powder, and various alloy powders of these, or Al, Cr, M
Various conventionally known magnetic powders such as alloy powders containing elements such as n, Si, and Zn, and barium ferrite powders are widely used.

Further, as the organic solvent, methyl isobutyl ketone,
Methyl ethyl ketone, cyclohexanone, toluene, ethyl acetate, tetrahydrofuran, dioxane, dimethylformamide and the like are used alone or as a mixture of two or more.

〔Example〕

 Next, an embodiment of the present invention will be described.

Example 1 Chemical formula (Where k is 91 mol%, l is 3 mol%, m is 5 mol%, and n is 1 mol%.) -Vinyl chloride-vinyl acetate-vinyl alcohol containing _two groups of -OPO (OH) The copolymer and monoethanolamine are allowed to coexist in a 1: 1 mixed solvent of toluene and methyl isobutyl ketone kept at 40 ° C., and are reacted by stirring for 2 hours to give a vinyl chloride-acetic acid having an average molecular weight of 40,000. A resin having a salt portion of monoethanolamine and phosphoric acid in a side chain of a vinyl-vinyl alcohol copolymer was obtained. Using the binder resin thus obtained, Co-containing γ-Fe ₂ O ₃ powder (average major axis diameter 0.2 μm, average axis ratio 1 /
4) 600 parts by weight The binder resin 120 parts by weight Myristic acid 2 parts by weight Cyclohexanone 400 parts by weight Toluene 400 parts by weight was mixed and dispersed in a sand mill for 8 hours to prepare a magnetic paint. This magnetic paint was applied on a polyester film having a thickness of 14 μm to a drying pressure of 4 μm, dried, subjected to a surface treatment, and cut into a predetermined width to prepare a magnetic tape.

Example 2 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of myristylamine was used in place of monoethanolamine in the synthesis of the binder resin in Example 1, and a resin tape was prepared. Was.

Example 3 In the synthesis of the binder resin in Example 1, the same procedure as in Example 1 was carried out except that the phosphate ester-modified polyurethane resin was used in the same amount instead of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 4 The synthesis of the binder resin in Example 2 was repeated except that the phosphate ester-modified polyurethane resin was used in the same amount in place of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to prepare a magnetic tape.

Example 5 In the synthesis of the binder resin in Example 1, the same procedure as in Example 1 was carried out except that the same amount of the phosphate-modified polycarbonate resin was used instead of the phosphate-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to prepare a magnetic tape.

Example 6 A binder resin was synthesized in the same manner as in Example 5, except that the same amount of myristylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 5,
I made a magnetic tape.

Example 7 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of isopropylamine was used instead of monoethanolamine in the synthesis of the binder in Example 1, and a magnetic tape was produced.

Example 8 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of cyclohexylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was produced. .

Example 9 A binder resin was synthesized and a magnetic tape was prepared in the same manner as in Example 1 except that the same amount of isopropanolamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. .

Example 10 In the synthesis of the binder resin in Example 7, except that the phosphate ester-modified polyurethane resin was used in the same amount instead of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 11 In the synthesis of the binder resin in Example 7, the same procedure as in Example 7 was carried out except that the phosphate ester-modified polycarbonate resin was used in the same amount in place of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 12 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of diethylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was produced.

Example 13 A binder resin was synthesized and a magnetic tape was prepared in the same manner as in Example 1 except that the same amount of diisopropylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. .

Example 14 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of dicyclohexylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was produced. .

Example 15 In the synthesis of the binder resin in Example 1, the same amount of 2- (methylamino)-was used instead of monoethanolamine.
A binder resin was synthesized in the same manner as in Example 1 except that ethanol was used, and a magnetic tape was produced.

Example 16 In the synthesis of the binder resin in Example 12, except that the phosphate ester-modified polyurethane resin was used in the same amount instead of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer, A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 17 In the synthesis of the binder resin in Example 12, the same procedure as in Example 12 was carried out except that the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used and the same amount of the phosphate ester-modified polycarbonate resin was used. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 18 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of triethylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1.
I made a magnetic tape.

Example 19 A binder resin was synthesized in the same manner as in Example 1, except that the same amount of N, N-diisopropylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, I made a tape.

Example 20 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of N-methylditanolamine was used in place of monoethanolamine in the synthesis of the binder resin in Example 1, and the binder resin was synthesized. I made a tape.

Example 21 The synthesis of the binder resin in Example 18 was repeated except that the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used in place of the phosphate ester-modified polyurethane resin in the same amount. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 22 In the synthesis of the binder resin in Example 18, except that the same amount of the phosphate-modified polycarbonate resin was used instead of the phosphate-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 23 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of sym-dimethylethylenediamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was prepared. Was.

Example 24 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of diethylenetriamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was produced.

Example 25 In the synthesis of the binder resin in Example 23, except that the phosphate ester modified polyurethane resin was used in the same amount in place of the phosphate ester modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer, Example 23 was used. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 26 In the synthesis of the binder resin in Example 23, except that the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used instead of the phosphate ester-modified vinyl chloride-vinyl alcohol copolymer, the same amount of the phosphate ester-modified polycarbonate resin was used. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 27 A binder resin was synthesized and a magnetic tape was prepared in the same manner as in Example 1 except that the same amount of 2-methoxyethylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. Was.

Example 28 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of 2-methoxyisopropylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was used. Was made.

Example 29 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of 2-methoxyethylethylamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1, and a magnetic tape was prepared. I made it.

Example 30 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of 2-methoxyethylisopropylamine was used in place of monoethanolamine in the synthesis of the binder resin in Example 1, and the binder resin was synthesized. I made a tape.

Example 31 In the synthesis of the binder resin in Example 27, Example 27 was repeated except that the phosphate ester-modified polyurethane resin was used in the same amount in place of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 32 In the synthesis of the binder resin in Example 27, Example 27 was repeated except that the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used instead of the phosphate ester-modified vinyl chloride-vinyl alcohol copolymer in the same amount. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 33 A binder resin was prepared in the same manner as in Example 1 except that the same amount of ethyl 3-N, N-dimethylaminopropionate was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. We synthesized and made a magnetic tape.

Example 34 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of N, N-dimethylglycine ethyl ester was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. , Made a magnetic tape.

Example 35 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of N, N-dimethylalanine ethyl ester was used in place of monoethanolamine in the synthesis of the binder resin in Example 1. I made a magnetic tape.

Example 36 In the synthesis of the binder resin in Example 1, the same amount of propionic acid 2-N, N-
A binder resin was synthesized in the same manner as in Example 1 except that dimethylaminoethyl ester was used, and a magnetic tape was produced.

Example 37 In the synthesis of the binder resin in Example 1, the same amount of propionic acid 3-N, N-
A binder resin was synthesized in the same manner as in Example 1 except that dimethylaminopropyl ester was used, and a magnetic tape was produced.

Example 38 In the synthesis of the binder resin in Example 33, except that the phosphate ester-modified polyurethane resin was used in the same amount in place of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer, Example 33 was used. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 39 Example 33 was repeated, except that in the synthesis of the binder resin in Example 33, the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used and the same amount of the phosphate ester-modified polycarbonate resin was used. A binder resin was synthesized in the same manner as described above to produce a magnetic tape.

Example 40 A binder resin was synthesized in the same manner as in Example 1 except that the same amount of N, N-dimethylethanolamine was used instead of monoethanolamine in the synthesis of the binder resin in Example 1. I made a magnetic tape.

Comparative Example 1 Example 1 was repeated except that the synthesis of the binder resin in Example 1 was omitted, and that 120 parts by weight of the phosphate ester-modified vinyl chloride-vinyl acetate-vinyl alcohol copolymer was used as a binder resin for the magnetic paint as it was. A magnetic tape was made in the same manner as described above.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 3, except that the synthesis of the binder resin in Example 3 was omitted, and that the phosphoric acid ester-modified polyurethane resin was used as a binder resin in a magnetic coating material as it was, 120 parts by weight. .

Comparative Example 3 Example 5 was repeated except that the synthesis of the binder resin in Example 5 was omitted, and that the phosphoric acid ester-modified polycarbonate resin was used as it was as a binder resin for the magnetic paint in an amount of 120 parts by weight.
A magnetic tape was made in the same manner as described above.

With respect to the magnetic tapes obtained in each of the examples and comparative examples, the mold ratio, jitter, still life and running durability were measured. Jitter and still life were obtained by using a magnetic tape recorder VT-8000E manufactured by Hitachi, Ltd. after leaving the obtained magnetic tape at 60 ° C., 10% RH and at 60 ° C., 80% RH for 10 days. It was measured. In addition, running durability was changed at 60 ° C and 80% RH,
The evaluation was made based on the time required to decrease by 3 dB.

 Tables 1 and 2 below show the results.

[Effects of the Invention] As is clear from the above Tables 1 and 2, the magnetic tapes (Examples 1 to 40) obtained by the present invention are compared with the conventional magnetic tapes (Comparative Examples 1 to 3). In each case, the jitter is small, the still life and running durability are long, and this indicates that the magnetic recording medium obtained by the present invention has sufficiently improved heat resistance and running durability at high temperatures.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenji Kadoya 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell, Ltd. (56) References JP-A-62-6429 (JP, A) JP-A-62 -28920 (JP, A) JP-A-61-133012 (JP, A) JP-A-1-100727 (JP, A)

Claims (10)

(57) [Claims] 1. A magnetic recording medium having a magnetic layer comprising, together with magnetic powder, a binder resin having a salt moiety obtained by a reaction between phosphoric acid and an amine in a side chain of a molecule. 2. A binder resin having a general formula (However, l + m + n is 1 to 60 mol%, m + n is 0.5 to 2
0% and n is 0.5 to 5.0 mol%. ) A vinyl chloride resin containing _two groups of -OPO (OH),
2. The magnetic recording medium according to claim 1, which is a vinyl chloride resin obtained by reacting with an amine. 3. The magnetic recording medium according to claim 1, wherein the binder resin is a resin selected from a polyurethane resin, a polycarbonate resin, a phenoxy resin, a polyester resin, a cellulose resin, and a butyral resin. 4. The magnetic recording medium according to claim 1, wherein said amine is a primary amine. 5. The magnetic recording medium according to claim 1, wherein said amine is a secondary amine. 6. The magnetic recording medium according to claim 1, wherein said amine is a tertiary amine. 7. The compound according to claim 1, wherein the amine has a general formula (Where R ₁ , R ₂ , R ₃ , and R ₄ are H or an alkyl group having 1 to 20 carbon atoms, p, q, and r are integers of 1 to 10, and x is 0 or 1). 4. The magnetic storage medium according to claim 1, wherein the magnetic storage medium is a polyamine. 8. The magnetic storage medium according to claim 1, wherein said amine is an amino alcohol. 9. The magnetic storage medium according to claim 1, wherein said amine is an amino ether. 10. The method according to claim 1, wherein the amine is a carboxylic acid ester having an amino group.
The described magnetic storage medium