JPH0375936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium for video with improved durability and runnability. Generally, a magnetic recording tape is obtained by applying a magnetic paint containing magnetic powder and a binder as main components onto a non-magnetic film. This magnetic paint contains various dispersants and surfactants to improve the dispersibility of the magnetic powder, and lubricants to improve durability and runnability. However, when magnetic recording tapes are used in video cassettes and the like, they are exposed to harsh usage conditions and usage conditions, so they are required to have better physical properties than ever before. In particular, improvements in runnability under high temperature and high humidity conditions and room temperature and low humidity conditions, improvement in still characteristics, and prevention of powder falling are important factors for the durability of magnetic recording tapes. Although it is known to use silicone oil and fatty acids to improve running performance,
This method has insufficient durability and is unsuitable for use in video cassettes that are exposed to severe usage conditions. It is also known to use fatty acids and fatty acid esters together in order to improve still characteristics. However, although this method is effective in improving still characteristics, it cannot be used in a wide range of environmental conditions, the repetitive running characteristics are insufficient when running under high temperature and high humidity conditions, and tape squeal occurs. However, there are drawbacks such as deterioration of still characteristics. The present invention provides a magnetic recording medium with particularly improved durability and runnability. The magnetic recording medium according to the present invention has a magnetic layer mainly composed of ferromagnetic powder and a binder formed on a non-magnetic support, and the magnetic layer includes fatty acids having 12 to 22 carbon atoms, It consists of a fatty acid ester whose fatty acid residue has 14 to 22 carbon atoms and a silane coupling agent. The fatty acids used in this invention are saturated and unsaturated fatty acids having 12 to 22 carbon atoms. Such saturated fatty acids include lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, eicosanoic acid, heneicosanoic acid, pehenic acid, and the like. Such unsaturated fatty acids include those having one or more unsaturated double bonds, such as dodecenoic acid, tetradecenoic acid, hexadecenoic acid, octadecenoic acid, oleic acid, elaidic acid, eicosenoic acid, docosenoic acid, and linoleic acid. It will be done. These are 2
It can also be used as a mixture of more than one species. Furthermore, the fatty acid ester used in this invention has a fatty acid residue having 13 to 13 carbon atoms.
22, and is an unsaturated or saturated fatty acid ester consisting of an alkyl group whose ester moiety preferably has 1 to 10 carbon atoms. This fatty acid ester can be obtained by reacting an unsaturated or saturated fatty acid with an alkyl alcohol or a substituted alkyl alcohol according to a conventional method. As the unsaturated or saturated fatty acid, any of the aforementioned fatty acids having 13 to 22 carbon atoms can be used. Also,
The alkyl group or substituted alkyl group constituting the ester moiety includes methyl, ethyl, propyl,
n-butyl, sec-butyl, tert-butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, methoxymethyl, ethoxyethyl, propoxyethyl, n-butoxyethyl, sec-butoxyethyl, tert-butoxyethyl, pentaoxy Ethyl, hexaoxyethyl, heptaoxyethyl, octaoxyethyl, ethoxypropyl, butoxypropyl, pentaoxypropyl, hexaoxypropyl, ethoxybutyl, propoxybutyl, butoxybutyl, pentaoxybutyl, hexaoxybutyl, ethoxyheptyl, ethoxyoctyl Examples include alkoxyalkyl such as. Specifically, such fatty acid esters include methyl tridecanoate, ethyl tridecanoate, octyl tridecanoate, methyl myristate, ethyl myristate, propyl myristate, octyl myristate, ethyl palmitate, hexyl palmitate, Octyl palmitate, octyl pentadecanoate, methyl stearate, ethyl stearate, n-butyl stearate, sec-butyl stearate, tert-butyl stearate, n-amyl stearate, heptyl stearate, octyl stearate, Saturated fatty acid alkyl esters such as nonyl stearate, decyl stearate, octyl heptadecanoate, n-butyl arachinate, propyl arachinate, octyl nonadecanoate, octyl eicosanate, octyl docosanoate;
Methoxymethyl tridecanoate, ethoxyhexyl tridecanoate, ethoxyoctyl tridecanoate, ethoxyethyl myristate, propoxyethyl pentadecanoate, n-butoxyethyl palmitate, sec-butoxyethyl palmitate, tert-butoxyethyl palmitate ,
Methoxyoctyl palmitate, n-butoxyethyl stearate, sec-butoxyethyl stearate, tert-butoxyethyl stearate, ethoxyhexyl stearate, methoxyheptyl stearate, methoxyoctyl stearate,
Methoxynonyl stearate, butoxypropyl heptadecanoate, pentaoxypropyl arachinate, butoxypropyl nonadecanoate,
Saturated fatty acid alkoxyalkyl esters such as hexakaxypropyl eicosanate and hexaoxybutyl docosanoate; and dodecenate, tetradecenate, having the above-mentioned ester group;
Examples include hexadecenate, octadecenate, oleate, elaidiate, eicosenate, docosenate, and linoate. Furthermore, the silane coupling agent used in this invention has the general formula: R _n -Si(R ₁ ) _o (R ₂ ) _3-o (wherein R is a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, haloalkyl group, aminoalkyl group, mercaptoalkyl group, aminoalkylaminoalkyl group, epoxyalkyloxyalkyl group, epoxycycloalkylalkyl group or acyloxyalkyl group, m means 0 or 1, R ₁ and R ₂ are the same or different and mean a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an acyloxy group, or an alkoxyalkyloxy group, and n means an integer from 1 to 3. However, , R ₁ and R ₂ cannot be hydrogen atoms at the same time). In the above general formula, the halogen atom is a chlorine or bromine atom, etc., and the alkyl group is a saturated aliphatic hydrocarbon residue having a linear or branched carbon atom number, such as a methyl group, an ethyl group, a propyl group, An alkenyl group such as a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, etc. is an unsaturated aliphatic hydrocarbon residue having a linear or branched carbon atom number, such as a vinyl group, a propenyl group, etc. , butenyl group, pentenyl group, etc. Haloalkyl groups include chloromethyl group, chloroethyl group, chloropropyl group, chlorobutyl group, dichloropropyl group, trichloropropyl group, etc. Aminoalkyl groups include aminomethyl group, aminoethyl group, aminopropyl group Mercaptoalkyl groups include mercaptomethyl, mercaptoethyl, and mercaptopropyl groups; aminoalkylaminoalkyl groups include aminomethylaminomethyl, aminoethylaminoethyl, and aminoethylaminopropyl; epoxyalkyloxyalkyl groups include glycidyloxyethyl group, glycidyloxypropyl group, etc.
The epoxycycloalkylalkyl group is (3,4-
Epoxycyclohexyl)ethyl group, (3,4-
Acyloxyalkyl groups such as epoxycyclohexyl)propyl group include acryloyloxyethyl group, acryloyloxypropyl group, methacryloyloxyethyl group, methacryloyloxypropyl group, and aryl group includes phenyl group. In addition, in R ₁ and R ₂ of the above general formula, the halogen atom is a chlorine atom, a bromine atom, etc., and the alkoxy group is a methyloxy group, an ethyloxy group,
Propyloxy group, butoxy group, sec-butoxy group, tertiary butoxy group, etc., and alkoxyalkyloxy group includes methoxymethoxy group, methoxyethoxy group, methoxypropoxy group, ethoxyethoxy group, ethoxypropoxy group, ethoxybutoxy group, etc. can be mentioned. Specifically, examples of silane coupling agents include halosilanes such as trichlorosilane and silicone tetrachloride, methyldichlorosilane, dimethyldichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, amyltrichlorosilane, and hexyltrichlorosilane. alkylhalosilanes,
Alkenylhalosilanes such as vinyltrichlorosilane and methylvinyldichlorosilane, arylhalosilanes such as phenyltrichlorosilane,
Methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, amyltriethoxysilane, hexyltriethoxysilane,
Alkylalkoxysilanes such as dimethyldiethoxysilane, alkenylalkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyltriethoxysilane,
Aryl alkoxysilanes such as phenyltrimethoxysilane and phenyltriethoxysilane,
Aminoalkylalkoxysilanes such as β-aminoethyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, β-mercaptoethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercapto Mercaptoalkylalkoxysilanes such as propyltriethoxysilane, aminoalkylaminoalkylalkoxysilanes such as N-β-aminoethyl-γ-aminopropyltriethoxysilane, haloalkylalkoxysilanes such as γ-chloropropyltrimethoxysilane, Alkenylalkoxyalkoxysilanes such as vinyl-tris(2-methoxyethoxy)silane, alkenylacyloxysilanes such as vinyltriacetoxysilane, γ
-acryloxypropyltrimethoxysilane, γ
- methacryloxypropyltrimethoxysilane,
γ-acryloxypropyltributoxysilane,
Acyloxyalkoxysilanes such as γ-methacryloxypropyltributoxysilane, acyloxyalkoxyalkoxysilanes such as γ-acryloxypropyl-tris(2-methoxyethoxy)silane, γ-methacryloxypropyl-tris(2-methoxyethoxy)silane, etc. γ-glycidyloxypropyltrimethoxysilane, γ
- Epoxyalkylalkoxysilanes such as glycidyloxypropyltriethoxysilane, β
Examples include epoxycycloalkylalkoxysilanes such as -(3,4-epoxycyclohexyl)ethyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane. Furthermore, triaminoalkyltrialkoxysilanes, aminosilanes, ureidomodifthide aminosilanes, silyl peroxides, and the like can also be used as silane coupling agents. The amounts of the aforementioned additives such as fatty acids, fatty acid esters, and silane coupling agents are preferably in the range of about 0.5 to 5% by weight, respectively, based on 100% by weight of the magnetic powder. If the amount of fatty acids becomes too large, the magnetic coating becomes plasticized, causing a large amount of powder to fall off, causing head clogging, and decreasing durability. In addition, if the amount of fatty acid ester is too large, the friction becomes too large, which impedes running properties. Furthermore, if the amount of silane coupling agent is too large, the stability of the magnetic paint is impaired, and C/ N
If the ratio deteriorates, or in even worse cases, the magnetic paint will gel, which is undesirable. Moreover, in any case, if the amount used is too small, the desired effect may not be achieved. By the way, fatty acids are lubricants that exhibit excellent lubricity under all environments, but due to their molecular structure, they are extremely easy to adsorb to the surface of magnetic powder and the like. Therefore, if a large amount of this is used, powder drop-off is likely to occur, resulting in decreased durability. However, by using a silane coupling agent with high adsorption capacity, the surface of the magnetic powder is covered with the silane coupling agent, and as a result of the interaction between the silane coupling agent and the binder, a high degree of interfacial reinforcement is performed. Powder falling due to adsorption and binder plasticization are less likely to occur. This makes it possible to obtain a magnetic recording medium that has even better durability and runnability in all environments, together with the improvement in still resistance due to the fatty acid ester. The magnetic powder used in this invention includes:
In particular, it is not limited in any way as long as it is used in coating type magnetic recording media, for example, γ-
Fe ₂ O ₃ , Fe ₃ O ₄ , γ-Iron oxide in an oxidation state intermediate between Fe ₂ O ₃ and Fe ₃ O ₄ , Co-containing γ-Fe ₂ O ₃ , Co-containing γ
- Iron oxide in an oxidation state intermediate between _{Fe 2} O ₃ and Fe ₃ O ₄ , iron oxide containing one or more metal elements (particularly transition metal elements), iron oxide containing Co
Those with a coating layer mainly composed of oxides or hydroxides, CrO ₂ , CrO ₂ by reducing the surface _of CrO ₂
Oxide-based magnetic powder such as layer-formed powder or
Metals such as Fe, Co, Ni, etc. Or Fe-Co alloy,
Fe-Ni alloy, Fe-Co-Ni alloy, Co-Ni-P alloy, Co-Ni-Fe-B alloy, Fe-Ni-Zn alloy,
Examples include ferromagnetic fine powder of alloys such as Fe-Mn-Zn alloy and Fe-Co-Ni-P alloy. Magnetic paint also uses aluminum oxide as an abrasive.
Chromium oxide, silicon oxide, etc., antistatic agents such as carbon black, lubricants such as molybdenum disulfide, graphite, silicone oil, olive oil, etc., and dispersants such as lecithin can be added. In addition, examples of binders that can be used include vinyl chloride-
Vinyl acetate copolymer, vinyl chloride-vinyl propionate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl propionate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer Polymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-
Vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-
Acrylic acid copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, styrene-butadiene copolymer, formal resin, acetal resin, butyral resin, phenolic resin, polyester resin, polyurethane resin, polyamide resin,
Examples include urea resin, urea-formaldehyde resin, melamine resin, epoxy resin, alkyd resin, phenoxy resin, polyvinyl fluoride, and mixtures thereof. Furthermore, usable solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohols such as methanol and ethanol, esters such as methyl acetate, ethyl acetate, butyl acetate, and ethyl butyrate, and ethylene glycol monoethyl. Examples include glycol ethers such as ether, ethylene glycol dimethyl ether, and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene, and aliphatic hydrocarbons such as hexane and heptane. The magnetic paint having the above-mentioned structure is applied to a non-magnetic support by a conventional coating method such as a doctor blade method or a gravure coating method to form a desired magnetic recording medium. Examples of the nonmagnetic support used include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose diacetate and cellulose triacetate,
Polycarbonate, polyvinyl chloride, polyimide, polyamide, metals such as aluminum and copper,
Examples include paper. Hereinafter, the present invention will be explained by Examples with reference to Comparative Examples. Example 1 A magnetic paint having the following composition was prepared as follows. Composition (parts by weight) Co-coated γ-Fe ₂ O ₃ 100 Nitrocellulose 10 Thermoplastic polyurethane resin 15 Stearin 1 Ethyl myristate 1 γ-Glycidoxypropyltrimethoxysilane
1 Carbon black 3 _Al 2 O ₃ 3 Methyl isobutyl ketone: Methyl ethyl ketone: Toluene 250 (1:1:1) This composition was kneaded and dispersed in a sand mill, and then 15 parts by weight of a polyisocyanate compound (3 moles of tolylene dichloromethane) An adduct of isocyanate and 1 mol of trimethylolpropane) was added, and kneading and dispersion were continued to prepare a magnetic paint. This was applied onto a 14μ thick polyethylene terephthalate film so that the thickness after drying was 4μ.
Subsequently, the film was subjected to orientation treatment using a DC magnetic field, dried, and wound. After calendaring this 3/4
It was slit into inch-wide strips to create magnetic video tape. Example 2 A magnetic tape was produced in the same manner as in Example 1 except that oleic acid was used as the fatty acid instead of stearic acid. Example 3 A magnetic tape was prepared in the same manner as in Example 1 except that palmitic acid was used as the fatty acid in place of stearic acid, and ethyl stearate was used as the fatty acid ester in place of ethyl myristate. Comparative Example 1 A magnetic tape was prepared in the same manner as in Example 1 except that the silane coupling agent was not used. Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1 except that fatty acid ester and silane coupling agent were not used. Comparative Example 3 A magnetic tape was produced in the same manner as in Example 1 except that fatty acids were not produced. The table below shows the results of examining various properties of the magnetic tapes obtained in the Examples and Comparative Examples described above.

[Table] From the results in the above table, it is clear that the magnetic tape according to the present invention is superior in all characteristics to the magnetic tape of the comparative example.

Claims (1)

[Claims] 1. In a magnetic recording medium in which a magnetic layer mainly composed of ferromagnetic powder and a binder is provided on a non-magnetic support, the magnetic layer contains a fatty acid having 12 to 22 carbon atoms, and a fatty acid residue having a carbon atom number of 12 to 22 carbon atoms. is 13 to 22
A magnetic recording medium comprising a fatty acid ester and a silane coupling agent.