JPS6355549B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic coating composition. (Prior Art) Recently, magnetic materials for magnetic recording are required to have increasingly high performance. For this purpose,
Improving the magnetic powder is important, but the binder used when applying the magnetic powder onto a support such as a tape is also an important factor. Generally, when manufacturing magnetic tapes and the like, polyurethane resins are often used as resins for surface coatings, which are highly flexible and provide strong coatings. However, conventional polyurethane has a low ability to disperse magnetic powder, and to compensate for this, soybean lecithin or the like is used as a dispersant, but adverse effects such as bleeding occur during long-term use. To improve such dispersion ability, nitrocellulose, polyvinyl butyral,
Resins with good dispersibility such as vinyl chloride/vinyl acetate/vinyl alcohol copolymers have also been used in combination, but this has the disadvantage of poor abrasion resistance and flexibility. Various studies have been carried out with the aim of eliminating these drawbacks, such as (1) Japanese Patent Application Laid-open No. 44902/1982;
No. 51-44903, (3) No. 55-139634, (4) No. 55-
139636, (5) No. 56-68925, (6) to (9) No. 56-101643
Magnetic recording bodies described in Nos. 1 to 101646 are known. However, for example, (1) and (2) use urethane-modified epoxy resins that do not contain OH groups, and (3)
In ~(9), urethane resins with OH groups are used, but these are not modified with epoxy resins, and the number of OH groups is usually about 1 to 5, so dispersibility is poor. Although improvements have been made to some extent, it is still insufficient, and it also has drawbacks such as poor hydrolysis resistance and heat resistance. In addition, as a polyol component of OH group-containing polyurethane, (10) JP-A-57-60529 describes glycerin, etc.
There are methods that use hydroxy compounds with higher functionality, but in order to increase the OH group concentration and molecular weight, gelation occurs if the NCO/OH ratio approaches 1, and to avoid this, the NCO/OH ratio is When the molecular weight is lowered, the molecular weight becomes smaller, which has the disadvantage that the resulting coating film has lower strength. Furthermore(11)
Although a polyurethane elastomer and an epoxy resin using a specific isocyanate are used in JP-A-57-158022, there is still room for improvement in dispersibility. (Problems to be Solved by the Invention) An object of the present invention is to provide a magnetic coating composition in which the dispersibility of magnetic powder is significantly improved. Another object of the present invention is to provide a magnetic coating composition that has a high crosslinking density and excellent durability. (Means for solving the problems) The present invention incorporates SO ₃ M (M is an alkali metal or quaternary ammonium ion) group in the molecular chain at 0.1meq/
The present invention relates to a magnetic coating composition containing as main components an organic solvent solution of a modified polyurethane resin having an OH group of 0.1 meq/g or more and a magnetic powder. In the present invention, the modified polyurethane resin is, for example, an epoxy modified polyurethane containing an SO ₃ M group obtained by reacting a polyol, an isocyanate compound, an epoxy resin having one or more OH groups in the molecule, and a diol containing an SO ₃ M group. , amines, carboxylic acids, and phenols to further impart an OH group. Furthermore, for example, a modified polyurethane containing an SO ₃ M group and a COOH group obtained by reacting a polyol, an isocyanate compound, a dihydroxycarboxylic acid, and a diol having an SO ₃ M group is reacted with an epoxy compound to further form an OH group. It can also be obtained by adding Further, it is optional to use a chain extender in the above urethanization reaction. In the present invention, various polyester polyols, polyether polyols, and other polyols can be used as the polyol. Specific examples of polyester polyols include adipate polyols such as polyethylene adipate polyol, polybutylene adipate polyol, and polyethylene propylene adipate polyol, terephthalic acid polyols (e.g., Toyobo Co., Ltd., products Vylon RUX and Vylon RV-200L), and polyester polyols. Examples include caprolactone polyol (eg, Daicel Chemical Co., Ltd., trade names Plaxel 212 and Plaxel 220). Specific examples of polyether polyols include polyoxyethylene glycol, polyoxypropylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxytetramethylene polyol, and the like. In addition, other polyols include polycarbonate polyols (e.g., West Germany, Bayer AG, trade name Desmofene 2020E), polybutadiene polyols (Ryuu, Nippon Soda, trade names G-1000, G-
2000, G-3000, Idemitsu Petrochemical, product name Polybd
R-45HT), polypentadiene polyol, castor oil polyol, and the like. These polyols can be used alone or in combination of two or more. Various isocyanate compounds are exemplified, such as diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), and 2,6-tolylene diisocyanate (2.6-TDI). , tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), isophorone diisocyanate (IPDI),
Examples include diisocyanates such as hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), and lysine diisocyanate (LDI), and polyisocyanates such as carbodiimide-modified MDI, and these can be used alone or in combination of two or more. Examples of epoxy resins having one or more OH groups in the molecule include bisphenol type epoxy resins and novolak type epoxy resins. Examples of the former bisphenol type include Epicote 828, 834, 1001, and 1002. ,1003,
1004, 1007, 1009 (all manufactured by Shell Chemical), etc. Examples of the latter novolak type include Epicote 152, 154, Sumiepoxy ELPN-180,
Phenol novolak epoxy resin such as ESPN-180, Sumiepoxy ESCN220L, 220F,
220HH, ESMN-220L, etc. manufactured by Nippon Kayaku Co., Ltd.
Examples include cresol novolak epoxy resins such as EOCN-102, 103, and 104. Further, as the diol having an SO ₃ M (M is an alkali metal or quaternary ammonium ion) group, the following (1) to (3) can be cited as representative examples. (1) Obtained by reacting dicarboxylic acid or its dialkyl ester (especially methyl ester), diol (ethylene glycol, butanediol, hexanediol, neopentyl glycol, diethylene glycol, etc.), and dimethylisophthalic acid-5-sulfonate. Polyester diol with a molecular weight of 500 to 3000, (2) General formula (R represents an alkylene group having 2 to 6 carbon atoms); (3) A diol with a molecular weight of 300 to 3000 obtained by reacting the above isophthalic diol or its ethylene glycol solution and ε-caprolactone. Lactone polyester diol. In the above isophthalic acid diol, R is -
The compound CH ₂ CH ₂ − has the trade name DEIS (manufactured by Sumitomo Chemical)
It is known as. In the present invention, one example of the modified polyurethane resin has an NCO Index of about 0.7 to 1.2, preferably about 0.9 to
1.1 to obtain an epoxy-modified polyurethane containing an SO ₃ M group, which was then subjected to a ring-opening reaction with at least one of amines, carboxylic acids, and phenols. In the above, examples of amines include primary amines such as ethylamine and n-butylamine, secondary amines such as diethylamine, dipropylamine, and dibutylamine, ethanolamine, N-
Alkanolamines such as methylethanolamine, N-butylethanolamine, diethanolamine, and dipropanolamine, and carboxylic acids such as acetic acid, propionic acid, stearic acid,
Succinic acid, adipic acid, maleic acid, benzoic acid,
Phthalic acid, phenylacetic acid, hydroxyacetic acid (glycolic acid), lactic acid, 2,2-dimethylolpropionic acid, 9,10,12,13-tetraoxyoctadecanoic acid, acetic anhydride, succinic anhydride, maleic anhydride, anhydride Examples include phthalic acid. Further, as the phenols, phenol, cresol, etc. are preferable. These amines, carboxylic acids and phenols can be used alone or in combination. As a chain extender, for example, 2 with a molecular weight of 500 or less
~6-functional polyol and 1 with a molecular weight of 500 or less
Examples include diamines having a primary or secondary unterminated amino group. Suitable chain extenders include (a) ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, hexanediol,
Polyols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (b) hydrazine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 1,
Diamines such as 4-cyclohexanediamine (c) Alkanolamines such as ethanolamine, diethanolamine, and triethanolamine (d) Hydroquinone, pyrogallol, 4,4-isopropylidene diphenol, aniline and the above polyols, diamines, Examples include polyols with a molecular weight of 500 or less obtained by adding propylene oxide and/or ethylene oxide to alkanolamines in any order. In the ring-opening reaction of the present invention, it is preferable to open all the epoxy groups, but of course some epoxy groups may remain, and usually amines, carboxylic acids and/or phenols are added to the epoxy group. It is preferable to use less than about 1 equivalent, preferably about 0.2 to 1 equivalent. The reaction is usually about 20-180℃,
Preferably, the temperature is about 100 to 150°C. In this case, it is possible to use known catalysts for curing epoxy resins, and tertiary amine and imidazole catalysts are particularly effective. Next, other examples of the modified polyurethane resin of the present invention include the above polyol, isocyanate compound, SO ₃ M
The following epoxy compound is reacted with a modified polyurethane containing an SO ₃ M group and a COOH group, which is obtained by reacting a diol having a group with the dihydroxycarboxylic acid shown below. That is, examples of dihydroxycarboxylic acids include 2,2-dimethylolpropionic acid (DMPA),
Examples include tartaric acid, dioxyadipic acid, and furionic acid. Various types of epoxy compounds can be used, including epoxy compounds such as ethylene oxide, propylene oxide, and epichlorohydrin, OH group-containing epoxy compounds such as glycidol and glycerin diglycidyl ether, the aforementioned bisphenol type epoxy resins, Examples include novolac type epoxy resin. In the above, the urethanization reaction is usually NCO
It is best to carry out the index in the range of about 0.9 to 1.2, preferably about 0.95 to 1.1, and the epoxy compound is usually
The reaction is preferably carried out so that the COOH/epoxy equivalent ratio is in the range of about 0.4 to 2.0, preferably about 0.9 to 1.1. The reaction is usually carried out at about 60-180°C, preferably about
It is carried out at 80-150° C., it being also possible to use known catalysts. The modified polyurethane resin used in the present invention has SO ₃ M groups of 0.1 mgq/g or more and OH groups of 0.1 mgq/g or more in the molecular chain, and this modified polyurethane resin can be produced by a known method. ,
For example, it can be manufactured by a one-shot method, a prepolymer method, or the like. Urethane catalysts can also be used. The magnetic coating composition of the present invention has the above-mentioned SO ₃ M group and
It is obtained by mixing a modified polyurethane resin containing an OH group, a magnetic powder, and, if necessary, a polyfunctional incyanate compound. The NCO Index for magnetic paints is normally in the appropriate range of about 0.9 to 1.5, but it is preferable to make it higher when considering the active hydrogen contained in the magnetic powder and other additives. As the polyfunctional isocyanate compound, a polyisocyanate having two or more functional groups can be used. Preferred specific examples include the various isocyanate compounds mentioned above, and trifunctional isocyanates obtained from trimethylolpropane and TDI (trade name: Desmodyur L, manufactured by Bayer AG, West Germany; Coronate L, manufactured by Nippon Polyurethane Co., Ltd.);
Similar trifunctional isocyanates manufactured by Bayer (product names Desmodyur N-75, Desmodyur R, Desmodyur H, etc.), Hyprene L-100, Sofuranate UEX-
504SS, polymethylene polyphenyl isocyanate (PAPI), polymeric polyisocyanate (PPI), and the like. Various types of magnetic powder can be used in the present invention, including iron, chromium, nickel, cobalt, alloys thereof, oxides thereof, and modified products thereof. Specific examples of oxides include γ-
Fe ₂ O ₃ , ferrite, magnetite, CrO ₂ , etc.
Examples of modified products include cobalt-doped γ-Fe ₂ O ₃ and cobalt-doped Fe ₂ O ₃ .
Examples include a bertholide compound of Fe ₃ O ₄ . It is also possible to use magnetic powders having various surface areas, and particularly when using ferromagnetic powders with a specific surface area of 25 m ² /g or more determined from the amount of nitrogen adsorbed by the BET method, excellent magnetic properties can be obtained. The amount of magnetic powder mixed is modified polyurethane resin.
Preferably, the amount is about 50 to 2000 parts by weight per 100 parts by weight. In the present invention, thermoplastic polyurethane resins, vinyl chloride resins, vinylidene chloride resins, PVC/vinyl acetate/vinyl alcohol copolymer resins (manufactured by UCC, VAGH, etc.),
Nitrocellulose, polyvinyl butyral resin,
Resins such as polyester resins, alkyd resins, epoxy resins, acrylonitrile-butadiene rubbers, etc. can be blended. Various types of thermoplastic polyurethane resins can be used; specific examples include Paraprene 22S, 26S (manufactured by Nippon Polyurethane Co., Ltd.), Estan 5702, 5703, 5711, 5715 (manufactured by BF Gutdrich Co., Ltd.), Pandex T- 5201, 5205,
5102A (manufactured by Dainippon Ink Chemical Co., Ltd.) and the like. Furthermore, in the present invention, commonly used additives such as dispersants, lubricants, abrasives, and antistatic agents can be added as necessary. The magnetic paint of the present invention can be obtained by mixing the above-mentioned components by various known methods, and for example, a mixer, roll mill, ball mill, sand mill, high-speed impeller, etc. can be used. In particular, it is preferable to add the polyfunctional isocyanate compound after it has been sufficiently dispersed, since the pot life will be longer. Further, it is preferable to use an organic solvent during the production of the modified polyurethane resin of the present invention and the above-mentioned magnetic coating composition, and suitable solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; benzene, toluene,
Examples include aromatic hydrocarbons such as xylene, esters such as ethyl acetate and butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, 3-methoxybutyl acetate, ethylene glycol diacetate, dimethylformamide, and dimethylacetamide. The magnetic paint of the present invention can be applied to tapes, sheets, cards,
It is applied to various types of supports such as disks and drums. The support usually has a thickness of about 5 to 50μ,
It is preferably about 10 to 40μ, and suitable materials include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose acetate, polycarbonate, polyamide, polyimide, polyamideimide, and the like. Various methods can be used to apply the magnetic coating onto the support, such as impregnation coating, air doctor coating, air knife coating, blade coating, reverse roll coating, gravure coating, cast coating, and spray coating. After coating, the magnetic powder may be subjected to treatment to orient it if necessary, or dried if it contains a general organic solvent. The drying temperature is usually approx.
The temperature is about 20 to 100°C, and the drying time is about 5 minutes or more, preferably about 5 minutes to 24 hours. After drying, it is usually preferable to cure at 50 to 140°C for about 1 minute to 2 hours. Furthermore, if necessary, a surface smoothing treatment can be performed before or after curing, or the material can be cut into a desired shape. (Example) Reference examples, examples, comparative examples, and test examples of the present invention will be described in detail below. In addition, simply parts and %
"" indicates parts by weight and weight %. Reference example 1 Synthesis of SO ₃ Na group-containing diol Ethylene glycol was distilled off under reduced pressure from a 35% ethylene glycol solution of DEIS, and 86% of DEIS was obtained.
Obtain an ethylene glycol solution. 316g of this solution
To the mixture, 558 g of ε-caprolactone and 0.35 g of tetrabutyl titanate were added, and the mixture was heated at 190° C. for 3.5 hours to cause ring-opening addition of ε-caprolactone to obtain a glycol with a molecular weight of 634. Example 1 Byron RV-200L (manufactured by Toyobo, molecular weight 1960)
117g, Epicoat 1001 (made by Yuka Shell Epoxy,
Molecular weight 900) 15.3g, above SO ₃ Na group-containing diol
23.7g, diphenylmethane diisocyanate 28.7
g and 436 g of cyclohexanone were added, and the mixture was reacted at 80 to 100°C for 3 hours, and then 2.5 g of glycolic acid was added, and the mixture was reacted at 140 to 150°C for 4 hours. The resulting solution had a solid content of 30% and a viscosity of 120 cps (25° C.), and the modified polyurethane contained SO ₃ Na groups at 0.11 meq/g polymer and OH groups at 0.36 meq/g polymer. 100 parts of this modified polyurethane solution, Co-γ-ferrite (manufactured by Phizer Magnetics,
Pferrico-2674) 100 parts and methyl ethyl ketone
After putting 100 parts in a ball mill and kneading for 72 hours, 10 parts of Desmodyur L was added and kneading was further continued for 30 minutes to obtain a magnetic coating composition. This magnetic paint was applied onto a polyester film using a doctor blade, dried at room temperature for 2 hours, then heated and dried at 100℃ for 20 hours.
A magnetic coating film with a thickness of 6μ was obtained. Example 2 Byron RV200L (137.2g), SO ₃ Na group-containing diol 28.4g, dimethylolpropionic acid 2.7g,
TDI-100 (24.4g), cyclohexanone 447.5g
The mixture is reacted at 80 to 100°C for 3 hours, then 1.9 g of glycidol is added, and the mixture is reacted at 140°C for 4 hours. The resulting solution has a solid content of 30% and a viscosity of 130 cps (25°C).
The modified polyurethane contains SO ₃ Na groups.
It had 0.13 meq/g polymer and 0.21 meq/g polymer OH group. Thereafter, a magnetic coating composition and a magnetic coating film were obtained in the same manner as in Example 1 using this modified polyurethane solution. Comparative example 1 Byron RV200L (150.9g), SO ₃ Na group-containing diol 30.7g, MDI (31.3g), cyclohexanone
709.7g is reacted at 80-100°C for 3 hours. The resulting solution has a solid content of 30% and a viscosity of 230 cps (25°C).
The modified polyurethane contains SO ₃ Na groups.
It had 0.13 meq/g polymer. Thereafter, a magnetic coating composition and a magnetic coating film were obtained in the same manner as in Example 1 using this modified polyurethane solution. Comparative Example 2 Vylon RV200L (137.2g), _SO3Na group-containing diol 28.4g, TDI-100 (20.3g), and cyclohexanone 433.8g are reacted at 80 to 100°C for 3 hours. The resulting solution has a solid content of 30% and a viscosity of 210 cps (25°C).
The modified polyurethane contains SO ₃ Na groups.
It had 0.14meq/g polymer. Thereafter, a magnetic coating composition and a magnetic coating film were obtained in the same manner as in Example 1 using this modified polyurethane solution. Test Example 1 (Dispersibility Test) In order to examine the dispersibility of the magnetic coating, the surface gloss (60° gloss) of the magnetic coating was measured using a gloss meter (manufactured by Tokyo Denshoku, TC-180D). The better the dispersibility, the better the gloss. The results are shown in Table 1. Test example 2 (Blocking property test) The obtained magnetic coating film was cut into 1 cm width and 1 cm length.
The coated surfaces were overlapped by the same amount, a load of 10 g was placed on the overlapped parts, heated in an oven at 80°C for 1 hour, and after cooling to room temperature, peeling was performed and the state of blocking was examined. Display the results first. Evaluation ◎ No blocking at all 〇 Blocking but easy peeling △ Blocking and force required for peeling × Blocking and non-peelable test example 3 (Adhesion test) Cellophane adhesive tape is pressed onto the magnetic coating using a hand roller. Then, gently peel it off and check for dirt on the adhesive side of the tape. The results are shown in Table 1. Evaluation 〇 No stains observed △ Part of the magnetic coating has come off and is attached to the adhesive surface × The magnetic coating has peeled off [Table]

Claims (1)

[Claims] 1. A polyol, an isocyanate compound, an epoxy resin having one or more OH groups in the molecule, and
Obtained by reacting a diol with SO ₃ M group
Epoxy-modified polyurethane containing SO ₃ M groups is reacted with at least one of amines, carboxylic acids, and phenols to further add OH groups, and SO ₃ M (M is an alkali metal or 0.1 meq/quaternary ammonium ion) group
A magnetic coating composition containing as main components an organic solvent solution of a modified polyurethane resin having an OH group of 0.1 meq/g or more and a magnetic powder. 2 Modified polyurethane resin contains polyol, isocyanate compound, dihydroxycarboxylic acid and
Obtained by reacting a diol with SO ₃ M group
The composition according to claim 1, which is obtained by reacting a modified polyurethane containing SO ₃ M groups and COOH groups with an epoxy compound to further impart OH groups. 3. The composition according to any one of claims 1 to 2, further comprising a polyfunctional isocyanate compound.