JPS6195082A - Magnetic coating composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition with magnetic powder being significantly high in the dispersibility, by incorporating magnetic powder, etc. in an organic solvent solution of specific modified polyurethane resin. CONSTITUTION:The objective composition can be obtained by incorporating magnetic powder and other ingredients in an organic solvent (e.g., cyclohexane) solution of a modified polyurethane resin having in the molecular chain >=0.1meq/g of SO3M group (M is alkali metal or quaternary ammonium ion) and >=0.1meq/g of OH group. The amount of said magnetic powder is pref. 50-2,000pts. by wt. per 100pts. by wt. of the resin.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to magnetic coating compositions.

(Prior Art) Recently, magnetic materials for magnetic recording layers are required to have increasingly high performance. For this purpose, it is important to improve the magnetic powder, but the binder used when applying the magnetic powder onto a support such as tape is also an important factor.

Generally, when manufacturing magnetic tapes and the like, polyurethane resins are often used as surface coating resins, which provide a highly flexible and tough coating film. 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 conducted with the aim of eliminating these drawbacks, such as (1) Japanese Patent Application Laid-open No. 51-44902, (2) Japanese Patent Application Publication No. 51-44903, (3) Japanese Patent Application Publication No. 55-139694,
(4) No. 55-139636, (5) No. 56-689
No. 25, (6) to (9) 56-101643 to 101
Magnetic recording bodies described in No. 646 and the like are known. However, for example, in (1) and (2), a urethane-modified epoxy resin containing no OH group is used, and in (3) to (9),
Although urethane resin with OH groups is used in
These are not modified with epoxy resins, and the number of OH groups is usually about 1 to 5. Although improvements in dispersibility have been achieved to some extent, it is still insufficient, and It has disadvantages such as poor decomposition and heat resistance.

Also, as a polyol component of OH group-containing polyurethane (
10) 3 of glycerin etc. in JP-A No. 57-60529
There are some that use hydroxy compounds that are more than functional,
In order to increase the OH group concentration and molecular weight using this method, NC010
If the H ratio is brought close to 1, delta formation will occur, and if the NC010H ratio is made low to avoid this, the molecular weight will become small and the strength of the resulting coating film will be low. Furthermore, (11) JP-A-57-15SO22 discloses that specific isocyanates are used in
``U8TO''-'') Poquin resin has been used, but 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 includes So, M (M is an alkali metal or quaternary ammonium ion) group in the molecular chain of 0.1 eq/g or more,
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 O, 1 meq/g or more, and a magnetic powder.

In the present invention, modified polyurethane resins include, for example, polyols, incyanate compounds, epoxy resins having one or more OH groups in the molecule, and epoxy modified polyurethanes containing S'03M groups obtained by reacting diols having So and M groups. It can be obtained by reacting at least one of amines, carboxylic acids, and phenols to further impart an OH group. ! In addition, for example, modified polyurethane containing SO3M groups and COOH groups obtained by reacting polyols, isocyanate compounds, dihydroxycarboxylic acids, and diols having So and M groups is reacted with an epoxy compound to further impart OH groups. It can also be obtained by letting 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 polyethylene adipate polyol,
Adipate polyols such as polybutylene 7-dipate polyol and polyethylene propylene adipate polyol, terephthalic acid polyols (e.g., Toyobo Co., Ltd., product name Vylon RUX1 Vylon RV-20OL), polycaprolactone polyols (e.g., Daicel Chemical, product name Plaxel) 212, Praxel 220), etc.

Specific examples of polyether polyols include polyoxyethylene glycol, polyoxypropylene polyol, polyoxyethylene, polyoxypropylene polyol, and polyoxytetramethylene polyol.

In addition, other polyols include polycarbonate polyol (e.g., Neuer AG, West Germany, trade name Desmoreen 2020E), polybutadiene polyol (e.g., Nippon Soda, trade name G-1000, G-2QO0.G-30).
00, Idemitsu Petrochemical, trade name Polybd R-4
5HT), polypentadiene polyol, castor oil polyol, and the like.

These polyols can be used alone or in combination of two or more.

Various types of incyanate compounds are exemplified, such as diphenylmethane diisocyanate (M
DI), 2,4-tolylene diisocyanate (2,4-
T DI ), 2,6-tolylene diisocyanate (
2,6-T DI), trinon diisocyanate) (
TODI), xylylene diisocyanate (XDI),
naphthylene diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), lysine diisocyanate (LD
Diisocyanate such as I), carposiimide modified MDI
These polyisocyanates 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 novolac type epoxy resins. Examples of the former bisphenol type include Epicote 828.834.
．． 1001.1002.1003.1004,
100F, 1009 (manufactured by Shell Chemical), etc. Examples of the latter novolak type include Epikote 152.154, Sumiepoxy ELPN-1SO, E
Phenol novolac epoxy resin such as SPN-1SO, Sumiepoxy ESCN 220L, 220F,
Examples include cresol novolak epoxy resins such as 220HH% ESMN-220L and EOCN-102, 103, and 104 manufactured by Nippon Kayaku Co., Ltd.

In addition, the following (1) to (
3) can be cited as a representative example.

(1) Dicarboxylic acid or its dialkyl ester (
Polyester diols with a molecular weight of 500 to 3000 obtained by reacting diols (ethylene glycol, butanediol, hexanediol, neopentyl glycol, diethylene glycol, etc.) and dimethylisophthalic acid-5-sulfonate (particularly preferred are methyl esters), 2) An isophthalic acid diol represented by the general formula (R represents a fullkylene group having 2 to 6 carbon atoms); (3) A molecular weight obtained by reacting the above isophthalic acid diol or its ethylene glycol solution with ε-caprolactone. 300-3000 lactone polyester diol.

In the above isophthalic acid diol, R is CH2CH2
The compound - is known under the trade name DEIS (manufactured by Sumitomo Chemical Co., Ltd.).

In the present invention, one example of the modified polyurethane resin is NCOInc.
lex is about 0.7-1.2, preferably about 0.9-1.
1 to obtain an epoxy-modified polyurethane containing So and M groups, 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 ethylamine, n
-Primary amines such as butyl 7mine, diethylamine,
Secondary amines such as diprovinylamine and dibutylamine, ethanolamine, N-methylethanolamine,
Alkanolamines such as N-butylethanolamine, jetanolamine, and cibrobanolamine, and carboxylic acids such as acetic acid, propionic acid, stearic acid, succinic acid, 7-dipic acid, maleic acid, benzoic acid, 7-talic 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, 7-talic anhydride, and the like. Further, as the phenols, phenol, cresol, etc. are preferable. These amines, carboxylic acids and phenols can be used alone or in combination.

Examples of the chain extender include di- to hexafunctional polyols with a molecular weight of 500 or less and diamines having 7 primary or secondary terminal amide groups with a molecular weight of 500 or less. Suitable chain extenders include (a) ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanol, hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, 1.4-cyclohexanediol, 1.4 - Polyols such as cyclohexane dimetatool and xylylene glycol (b) Hydrazine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 1.4-1°he'f, ayoaga, etc. Tour 3. (C) Alkanolamines such as ethanolamine, jetanolamine, and triethanolamine (d) Hydroquinone, pyrogallol, 4,4-impropylidecidiphenol, aniline, and the above polyols, diamines, and alkanolamines Examples include polyols having a molecular weight of 500 or less obtained by adding propylene oxide and/or ethylene oxide to a polyol in any order.

The above rIf of the present invention! In the ring reaction, it is preferable to open all the epoxy groups, but of course some epoxy groups may remain, and usually amines,
It is preferable to use less than about 1 equivalent of carboxylic acids and/or phenols, preferably about 0.2 to 1 equivalent. The reaction temperature is usually 20 to 1 SO℃, preferably about 100 to 15
It is preferable to carry out the reaction at 0° 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, another example of the modified polyurethane resin of the present invention is a modified polyurethane containing So, M groups and coOH group obtained by reacting the above polyol, incyanate compound, diol having a 501M group, and the following dihydroxycarboxylic acid. The following epoxy compounds are reacted.

That is, examples of dihydroxycarboxylic acids include 2,2-dimethylolpropionic acid (DMPA), tartaric acid, dioxy7nopic acid, and 7a ionic acid.

Various types of epoxy compounds can be used, such as epoxy compounds such as ethylene oxide, propylene oxide, and epichlorohydrin, OH group-containing epoxy compounds such as glycidol and glycerin diglycyl ether, the aforementioned bisphenol type epoxy resins, and novolak. type of epoxy resin, etc.

In the above, the urethanization reaction is usually NC0I index
is preferably in the range of about 0.9-1.2, preferably about 0.95-1.1, and the epoxy compound usually has c.

The reaction is preferably carried out so that the OH/epoxy equivalent ratio is in the range of about 0.4 to 2.0, preferably about 0.9 to 1.1. The reaction is typically carried out at 60 to 1 SO°C, preferably about SO
It is carried out at a temperature of up to 150 DEG C., it being also possible to use known catalysts.

The above-mentioned modified polyurethane resin used in the present invention has SO3M groups in the molecular chain of 0. l+agQ/g or more, 0 OH group
．． This modified polyurethane resin can be produced by a known method, such as a one-shot method or a prepolymer method. Urethane catalysts can also be used.

The magnetic coating composition of the present invention can be obtained by mixing the modified polyurethane resin containing SO3M groups and OH groups, magnetic powder, and, if necessary, a polyfunctional isocyanate compound. The N COI index in a magnetic paint is normally in the range of 0.9 to 1.5, but it is preferably higher when considering the active hydrogen contained in the magnetic powder and other additives.

As the polyfunctional incyanate compound, a polyisocyanate having two or more functional groups can be used6.
Preferred specific examples include the various incyanate compounds mentioned above, and trifunctional incyanates obtained from trimethylolpropane and TDI (trade name: Desmodur L1, West Germany, manufactured by Bayer AG; Coronet L, manufactured by Nippon Polyurethane Co., Ltd.); Similarly, trifunctional incyanate manufactured by Bayer (product name: Desmodur N-75, Desmodur R1, Same H, etc.), 1
1 Ifren L-100, So75 N*-) UEX-5
04SS.

Polymethylene polyphenylisocyanate (PAPI)
, polymeric borysonane) (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-Fe2O3, ferrite, magnetite, CrO2, etc., and examples of modified products include γ-Fe20* doped with cobalt and Fe2O doped with cobalt.

Examples include bertolide compounds of and Fe, O, and the like. 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 m27 g or more determined from the amount of nitrogen adsorbed by the BET method, excellent magnetic properties can be obtained. The blending amount of magnetic powder is approximately 50 to 20 parts by weight per 100 parts by weight of modified polyurethane resin.
It is preferable to set it as 00 parts by weight. In the present invention, thermoplastic polyurethane υI resin, vinyl chloride resin, vinylidene chloride resin, vinyl chloride/vinyl acetate/
Vinyl alcohol copolymer tree @ (manufactured by IJCC, G to ■)
Resins such as nitrocellulose, polyvinyl butyral resin, polyester resin, alkyl resin, epoxy resin, and 7-crylonitrile-butadiene rubber can be blended.

Various types of thermoplastic polyurethane resins can be used as the thermoplastic polyurethane resin, but a specific example is Paraprene 22S.
, 26S (Japan Polyurethane Co., Ltd., Nissan 570
2.5) 03.5711.5715 (manufactured by BF Gutdrich), Bandex T-5201, 5205
, 5102A (manufactured by Dainippon Ink Chemical Co., Ltd.). 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, as this will extend the pot life. Also, when producing the modified polyurethane resin of the present invention, the above magnetic coating composition! ! ! ! It is preferable to use an organic solvent during production, and suitable solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, and xylene, ethyl acetate, and acetic acid. Examples include esters such as butyl, methyl cellosolve acetate, ethyl cellosolve acetate, 3-7 toxybutyl acetate, ethylene glycol diacetate 11 dimethylformamide, and trimethylacetamide.

The magnetic paint of the present invention can be applied to supports in various forms such as tapes, sheets, cards, disks, and drums. The support usually has a thickness of about 5-50μ, preferably about 10-50μ.
The diameter is preferably about 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 foot 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 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 electric test examples of the present invention will be described in detail below. Note that parts and percentages simply refer to heavy parts and weight percentages.

Reference Example I Synthesis EIS of 5OzNa group-containing nool
Ethylene glycol is distilled off under reduced pressure from the 35% ethylene glycol solution of DEIS to obtain an 86% ethylene glycol solution of DEIS. To 316 g of this solution, 558 g of ε-caprolactone was added (tetraptyl titanate) 0.
358 was added and 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 Hyane RV-20OL (manufactured by Toyo AM, molecular weight 1
960) 117g, 2 pico) 1001 (manufactured by Yuka Shell Epoxy, molecular weight 900) 15.3g, the above So,
23.7 g of Na group-containing 7-ol, 7 g of diphenyl tandiisocyanate 2B.

Add 436g of cyclohexanone and heat from SO to 100°C
2.5 g of glycolic acid was added, and the mixture was reacted at 140 to 150° C. for 4 hours. The obtained solution had a solid content of 30% and a viscosity of 120 cps (25'C), and the modified polyurethane had So and Na groups of 0.1 t + aeq.
/g polymer, and had OH groups of 0.36 toeq/g polymer.

100 parts of this modified polyurethane solution, CO-γ-ferrite (manufactured by Isa-Magnetics Co., Ltd., P ferr.
ico-2674) and 100 parts of methyl ethyl ketone were placed in a ball mill and mixed for 72 hours, then 10 parts of Desmodur 1 was added and mixed for an additional 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, and then heated and dried at 100°C for 20 hours to obtain a magnetic coating film with a thickness of 6 μm.

Example 2 Byron RV 2QOL (137,2g), SO,N
28.4 g of a group-containing diol, 2.7 g of dimethylolpropionic acid.

T DI-100 (24.4 g) and 447.5 g of cyclohexanone are reacted at SO to 100°C for 3 hours, 1.9 g of glycidol is added, and the mixture is reacted at 140°C for 4 hours.

The resulting solution had a solid content of 30% and a viscosity of 130 cps (25
°C), and the modified polyurethane has SO3N a groups of 0.130. /, polymer, OH group 0.21 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 1 Byron RV 200L (150.9g), So3N
g group-containing diol 30.7 g SMD r (31.3 g
>, 709.7 g of cyclohexanone is reacted at SO to 100° C. for 3 hours.

The resulting solution had a solid content of 30% and a viscosity of 230 eps (25
°C), and the modified polyurethane has So and Na groups at 06
It had 13 meq/g polymer.

Thereafter, a magnetic paint, an Ifl product, and a magnetic coating film were obtained in the same manner as in Example 1 using this modified polyurethane solution.

Comparative example 2 Pyro 7 RV 200L (137,2g), S O
s Na group-containing nool 28.4 g, T D l-
100 (20.3g), cyclohexanone 433.8g
is reacted at SO~100°C for 3 hours.

The resulting solution had a solid content of 30% and a viscosity of 210 cps (25
℃), and the modified polyurethane has 0 SO3N a groups.
．． It had 14 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.

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 Jiho Co., Ltd., T
C-108D). 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, the coating surfaces were overlapped by a length of 1c + a, and a load of Log was placed on the overlapped part and placed in an oven at SO ℃. The film was heated for 1 hour, allowed to cool to room temperature, and then peeled off to examine the progress of blocking. Display the results first.

Evaluation ◎ Not blocking at all ○ Blocking but easily peeling △ Blocking and force required for peeling × Blocking and non-peelable Test Example 3 (Applying cellophane adhesive tape to ffi adhesive paper test coating film using a hand roller Crimp the tape, peel it off slowly, and check for dirt on the adhesive side of the tape.

The results are shown in Table 1.

evaluation ○ No stains detected Δ Part of the magnetic coating has come off and is attached to the adhesive surface. × Magnetic coating peels off

Claims (4)

[Claims] (1) 0.1 meq/g or more of SO_3M (M is an alkali metal or quaternary ammonium ion) group in the molecular chain,
A magnetic coating composition containing as main components an organic solvent solution of a modified polyurethane resin containing 0.1 meq/g or more of OH groups and magnetic powder. (2) The modified polyurethane resin contains a polyol, an isocyanate compound, an epoxy resin having one or more OH groups in the molecule, and an epoxy modified polyurethane containing an SO_3M group, which is obtained by reacting a diol containing an SO_3M group. The composition according to claim 1, which is further provided with an OH group by reacting at least one of acids and phenols. (3) Modified polyurethane resin contains polyol, isocyanate compound, dihydroxycarboxylic acid and SO_3M
The composition according to claim 1, which is obtained by reacting an epoxy compound to a modified polyurethane containing an SO_3M group and a COOH group obtained by reacting a diol having the group to give an OH group. (4) The composition according to any one of claims 1 to 3, further comprising a polyfunctional isocyanate compound.