JPS63142517A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the affinity of a binder to magnetic powder and the viscosity characteristic of the binder and to improve durability by using a polyurethane/urea resin into the molecule of which -COOM and other specific polar groups are introduced as the binder. CONSTITUTION:The polyurethane/urea resin having at least one kind of the -SO3M group, -OSO3M group and -PO(OM')2 group as well as the -COOM group (M is H atom or alkali metal atom, M' is H atom, alkali metal atom, hydrocarbon group) is incorporated into the binder of a magnetic recording medium. The binder, therefore, exhibits the high affinity to the magnetic powder and has the good dispersibility even in the magnetic powder which is pulverized to hyper-fine particles or the magnetic powder having a large quantity of magnetization. Since the polyurethane/urea resin used for the binder has excellent heat resistance and tackiness, the thermal characteristics, blocking resistance and durability of the magnetic layer are greatly improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium such as a magnetic tape, and more particularly to a binder contained in a magnetic layer formed on a non-magnetic support. This is related to the improvement of.

[Summary of the invention]

The present invention provides a polyurethane-urea resin having a 13OJ group in its molecule, which is used as a binder for coated magnetic recording media.
-05O, M group, at least one of two -PO(OM') groups, and -C00M group (where M represents a hydrogen atom or an alkali metal atom, and M'' represents a hydrogen atom, an alkali metal atom, or a hydrocarbon group). By introducing the following: The objective is to provide a magnetic recording medium with excellent surface properties and durability, and good magnetic properties and electromagnetic conversion properties.

[Conventional technology]

In recent years, magnetic recording media, especially magnetic recording media for VTRs (video tape recorders), have improved their magnetic properties and electromagnetic conversion properties so that high playback output can be obtained even when recording at short wavelengths. It is requested. As a measure to this end, efforts have been made to make the magnetic powder particles finer and to increase the magnetic force, and there is a strong tendency to increase the packing density of the magnetic powder in the magnetic layer, that is, the so-called banking density.

On the other hand, conventionally used binders for magnetic recording media include binders mainly made of vinyl chloride-vinyl acetate copolymer, polyurethane resin, etc.; With the demand for improvements in durability and physical properties of coatings, various problems have arisen with binders mainly made of vinyl chloride and binders using polyurethane resin, and it is currently difficult to adequately address these problems. It is.

For example, as the specific surface area increases due to finer particles of magnetic powder and the cohesive force increases due to high magnetizing force, satisfactory dispersibility and surface area cannot be obtained with the above-mentioned binders, which increases the banking density of magnetic powder. It has also become difficult. Therefore, the durability, magnetic properties, and electromagnetic conversion properties were also insufficient. In particular, performance has been insufficient for magnetic powders made into ultrafine particles or magnetic powders with a high amount of magnetization in order to meet higher recording densities.

In this case, for example, a method such as using a surfactant as a dispersant may be considered, but since the surfactant is a low molecular weight, powder falling off and blooming due to changes over time may occur.
Problems arise in mechanical strength, durability, etc.

Therefore, for example, in Japanese Patent Publication No. 58-41565, etc.,
A binder in which a sulfonic acid metal base is introduced into a polyurethane resin has been proposed, and attempts have been made to improve the dispersibility of magnetic powder, but it is still far from satisfactory, and for example, when used as a magnetic recording medium. Powder fell off, and there was still room for improvement in terms of durability.

In addition, from the viewpoint of physical properties of the coating film, for example, polyurethane resins are suitable in terms of abrasion resistance, etc. However, since conventionally used polyurethane resins have a low softening point and poor heat resistance, If the medium is wound onto a reel and stored at high temperatures or for a long period of time, it will stick to the non-magnetic material that overlaps this magnetic layer, causing the magnetic layer to peel off and reduce its performance as a magnetic recording medium. The problem is that they are unable to perform.

[Problem that the invention seeks to solve]

In this way, conventionally widely used binders containing vinyl chloride copolymers, polyurethane resins, and sulfonic acid metal bases have problems in terms of dispersibility for magnetic powder, physical properties of coatings, handling during manufacturing, etc. There are many issues that need to be resolved,
It was difficult to ensure desired durability, magnetic properties, and electromagnetic conversion properties.

Therefore, the present invention has been proposed to solve the above-mentioned drawbacks in the technical field, and is aimed at improving the dispersibility of magnetic powder, the properties of the coating film when formed as a magnetic layer, and the workability when forming the coating film. We provide a binder with excellent properties such as
The object of the present invention is to provide a magnetic recording medium with excellent surface properties and durability, and good magnetic properties and electromagnetic conversion properties.

Means for Solving Problem C] The present inventors have discovered that the polyurethane-urea resin exhibits excellent properties, particularly in terms of physical properties of the coating film such as adhesiveness, and that the polyurethane-urea resin exhibits excellent properties in terms of coating film properties such as adhesiveness, and that a carboxylic acid metal base is added to the side chain as a polar group. By introducing it, it shows high affinity for magnetic powder and improves dispersibility.
Further, as polar groups, SOJ group, -0SO,M group,
The present invention was developed based on the fact that introducing a PO(OM')z group into the side chain is effective in improving workability. In a magnetic recording medium formed with a magnetic layer mainly composed of magnetic powder and a binder, the binder contains at least one of -503M group, -08OJ group, and two -PO(OM') groups in the molecule.
A polyurethane-urea resin having a species and a -C00M group (where M represents a hydrogen atom or an alkali metal atom, and Mo represents a hydrogen atom, an alkali metal atom, or a hydrocarbon group). It is.

The polyurethane-urea resin used in the present invention has urethane bonds and urea bonds in its molecules.
It is characterized by having a hydrophilic polar group as a side chain.

In addition, the urethane bond and urea bond described above play an important role in improving the thermal properties of the binder resin, and can increase the softening point temperature, which is a measure of heat resistance, and lower the glass transition point temperature, allowing a wide range of Stable physical properties of the magnetic layer are maintained over a temperature range, which is extremely effective in improving blocking resistance.

That is, the introduction of urea bonds can significantly improve the thermal properties of the resin, similar to urethane bonds. More importantly, the introduction of this urea bond makes it possible to obtain resins that are soluble when used in combination with ketone, alcohol, ester, aromatic hydrocarbon, and aliphatic hydrocarbon solvents. . In addition, since the concentration of polar parts (urethane bonds, urea bonds) in the polyurethane-urea resin molecules can be made higher than in general polyurethane resins, the interaction between molecules becomes stronger, and the resulting magnetic layer is coated. The physical properties of the film are improved and the durability is also improved. That is, by using a polyurethane-urea resin as a binder for a magnetic recording medium, a magnetic recording medium with excellent blocking resistance and durability can be provided.

The total concentration of urethane bonds and urea bonds in the polyurethane-urea resin was 1.8 mm.

1/g~3. It is preferable that Q is mmol/g.

If the concentration is less than 1.8 mmol/g, the softening point of the resin will be lowered and blocking resistance will not be improved; If it exceeds Q rr+n+61/g, it becomes insoluble in general-purpose solvents. Further, the ratio of urea bond concentration/urethane bond concentration is preferably 0.3 to 1.6. If the ratio of urea bond concentration/urethane bond concentration is less than 0.3, it will become insoluble in general-purpose solvents, and if the ratio of urea bond concentration/urethane bond concentration exceeds 1.6, the glass transition point of the resin will become high. Put it away.

Next, a method for producing polyurethane-urea resin will be described.

Polyurethane-urea resins are obtained by addition polymerizing long-chain diols, short-chain diols, organic diamines, and organic diisocyanates. In this addition polymerization, a mixture of a long-chain diol and a short-chain diol is reacted with an organic diisocyanate in advance to prepare a prepolymer with an isocyanate group terminal, and then an organic diamine is added to extend the chain and introduce a urea bond. It is carried out by the prepolymer method.

That is, according to this prepolymer method, the urethane chain is extended by the reaction between the OH group of the long-chain diol or short-chain diol and the NGO group of the organic diisocyanate.

The long-chain diol used in the production of the polyurethane-urea resin has a molecular weight of about 500 to 5,000, and is roughly classified into, for example, polyester diol, polyether diol, polyether ester glycol, and the like. Specific examples of polyester diols include succinic acid and adipic acid.

Aliphatic dicarboxylic acids such as sebacic acid and azelaic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, or lower alcohol esters thereof, ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1, Polyester diols obtained by reacting 6-hexane glycol, diethylene glycol, neopentyl glycol, or an ethylene oxide adduct of bisphenol A, or a mixture thereof, or a lactone obtained by ring-opening polymerization of a lactone such as ε-caprolactone. Examples include polyester diols and the like. Examples of polyether diols include polyethylene glycol, polypropylene ether glycol, polytetramethylene ether glycols, and copolymerized polyether glycols thereof. Examples of polyether ester glycols include polyester glycols obtained by reacting the above polyalkylene ether glycol as a polyol component with an aliphatic or aromatic dicarboxylic acid. If the molecular weight of this long-chain diol is too small, the urethane bond concentration of the resulting polyurethane-urea resin will become too large, resulting in poor flexibility of the resin and poor solubility in solvents, resulting in a binder for magnetic recording media. It is not very suitable for use as In addition, if the molecular weight of the long chain diol is too large, the long chain diol content in the resin will be too large and the urethane bond concentration will be relatively small.
The abrasion resistance and heat resistance of the resin decrease.

The short chain diol used in the production of the polyurethane-urea resin has a molecular weight of about 50 to 500, such as ethylene glycol, propylene glycol, 114-
These include aliphatic glycols such as butylene glycol, 116-hexane glycol, and neopentyl glycol, and aromatic diols such as ethylene oxide or propylene oxide adducts of bisphenol A and ethylene oxide adducts of hydroquinone. Depending on the properties, these can be used alone or in combination in various quantitative ratios.

In addition, the organic diamines include aliphatic diamines such as tetramethylene diamine and hexamethylene diamine, m
-phenylenediamine, p-phenylenediamine, 2.
4-) lylenediamine, 2,6. -) lylene diamine, m-xylene diamine, p-xylene diamine,
diphenylmethanediamine, 3,3'-dimethoxy-
Aromatic diamines such as 4,4′-biphenylenediamine, 3,3″-dimethyl-4,4′-biphenylenediamine, 4,4′-diaminodiphenyl ether, 1,5-naphthalenediamine, 2,4-naphthalenediamine, 1
．． Examples include alicyclic diamines such as 3-diaminomethylcyclohexane, 4,4'-diaminocyclohexylmethane, and isophoronediamine.

Examples of the organic diisocyanate include aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2.4-)lylene diisocyanate, 2.6-Dylene diisocyanate, diphenylmethane diisocyanate, 3,3-dimethoxy-4,4°-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-
Aromatic diisocyanates such as biphenylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 1,5-naphthalene diisocyanate, 2,4-naphthalene diisocyanate, 1,3-diisocyanate methylcyclohexane, Examples include alicyclic diisocyanates such as 1,4-diisocyanatomethylcyclohexane, 4,4'-diisocyanatodicyclohexylmethane, and isophorone diisocyanate.

Furthermore, in the above reaction, the molar ratio of the short chain diol to the long chain diol is preferably 3 or less. If this molar ratio is too large, the urethane bond concentration will become too high, and the produced polyurethane-urea resin will have
It cannot be dissolved in the above-mentioned general-purpose solvents used for producing magnetic paints, so it is not very suitable. Ethylene glycol, 1,4-butylene glycol, 1,6- as short chain diols
When using a straight chain diol such as hexane glycol,
The above molar ratio is desirably 1 or less, preferably 0.5 or less, and if a branched short chain diol such as neopentyl glycol or an ethylene oxide or propylene oxide adduct of bisphenol A is used, the solubility of the resin is good. The above-mentioned molar ratio can be increased compared to chain diols. However, even in this case, if the above-mentioned molar ratio is too large, exceeding 3, the solubility deteriorates, which is not preferable. Furthermore, depending on the molecular weight of the long-chain diol or short-chain diol, it is also possible to use them alone.

In producing the polyurethane-urea resin used in the present invention, the long-chain diols having a molecular weight of approximately 500 to 5,000 are selected from among the above-mentioned examples, particularly polyester diols,
Among them, polybutylene adipate, polyhexamethylene adipate, and polycuff.

Preferably, rolactone diol is used. Further, as the short chain diol having a molecular weight of about 50 to 500, among the above-mentioned examples, it is particularly preferable to use a branched short chain diol, especially neopentyl glycol.

Further, as the organic diamine, it is particularly preferable to use isophorone diamine among the above-mentioned examples. Among the organic diisocyanates mentioned above, it is particularly preferable to use 4,4-diphenylmethane diisocyanate and isophorone diisocyanate.

In addition, the reaction method adopted in the production of the polyurethane-urea resin according to the present invention includes melt polymerization in which the reaction is carried out in a molten state, and inert solvents such as ethyl acetate, methyl ethyl ketone, acetone, toluene, etc., alone or in combination, as described above. However, solution polymerization is preferable for the production of polyurethane-urea resins, which are often dissolved in solvents such as binders for magnetic recording media. In some cases, it is more preferable to carry out melt polymerization and then add the above-mentioned inert solvent to carry out solution polymerization before carrying out the chain extension reaction.

In the reaction, an organometallic compound such as an organotin compound such as stannous octylate or dibutyltin dilaurate, or a tertiary amine such as N-methylmorpholine or triethylamine may be added as a catalyst. Further, in order to increase the stability of the product, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, etc. may be added in an amount of about 5% or less based on the solid content.

Furthermore, -COOM group and -5OffM group, -O5O as hydrophilic polar groups in the polyurethane-urea resin.
At least one of a ffM group, a PO(OM')z group (where M represents a hydrogen atom or an alkali metal atom, and Mo represents a hydrogen atom, an alkali metal atom, or a hydrocarbon group)
Introducing seeds. Here, the -C00M group is very effective in improving the dispersibility of magnetic powder, and has a particularly large effect in reducing powder falling when used as a magnetic recording medium. When this is done, the viscosity becomes extremely large, making it impractical, so the hydrophilic polar group described above is also introduced.

According to experiments conducted by the present inventors, by using a polyurethane-urea resin that has a C00M group in its molecule and also has the above-mentioned hydrophilic polar group, a good result can be obtained without impairing the powder fall reducing effect of the C00M group. It has been found that it is possible to obtain a coating material having excellent viscosity characteristics, and to obtain a magnetic recording medium with better dispersibility than when the C00M group is contained alone.

By the way, these C00M groups, -803M groups, -O
3 (JM group, PO(OM')z group, etc.) can be introduced into the polyurethane-urea resin by the following method.

(1) A method in which the hydrophilic polar group is previously introduced into a part of diisocyanate, polyol, diamine, etc., which are raw materials for polyurethane-urea resin.

(2) A method in which an OH group is left at the terminal or side chain of a polyurethane-urea resin, and this OH group is modified with the above-mentioned compound having a hydrophilic polar group.

The diols, diisocyanates, and diamines into which hydrophilic polar groups are introduced used in the method (1) above include diols containing hydrophilic polar groups, organic diisocyanates containing hydrophilic polar groups, and organic diamines containing hydrophilic polar groups. can be mentioned. These compounds are polymerized with other raw materials to form part of the polymer molecular chain of the polyurethane-urea resin, and as a result, hydrophilic polar groups are introduced into the polyurethane-urea resin.

The hydrophilic polar group-containing diols include C00M group-containing diol, PO(OM')Z group-containing diol, SO3
These are M group-containing diol and 03OJ group-containing diol.

Examples of the C00M group-containing diol include dimethylolpropionic acid and compounds in which these C0OH groups are neutralized using a methanol solution of NaOH, a methanol solution of KOH, or the like. By synthesizing a polyurethane-urea resin using the above compound as a chain extender, a C00M group is introduced into the molecule.

The diol containing two PO(OM') groups has the general formula (wherein R1 is an alkylene group having 2 to 6 carbon atoms or a substituted product thereof, R2 is an alkylene group having 1 to 6 carbon atoms or a substituted product thereof, Ml and M2 represents an alkyl group having 1 to 6 carbon atoms.

) Examples include compounds represented by:

The -303M group-containing diol is obtained by reacting a carboxylic acid component that does not have an SO3M group, a glycol component, and a dicarboxylic acid component that has a -5O,M group.

Examples of the carboxylic acid component not having the -5OffiM group include terephthalic acid, isophthalic acid, orthophthalic acid,
．． Aromatic dicarboxylic acids such as 5-nuclic acid, aromatic oxycarboxylic acids such as p-oxybenzoic acid, P-(hydroxyethoxy)benzoic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc. Examples include aliphatic dicarboxylic acids, tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid.

The glycol components include ethylene glycol, propylene glycol, 1.3-propanediol, 1.
4-butanediol, 1,5-pencunediol,
6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2.
4-) Dimethyl-1,3-bentanediol, 1.4
- cyclohexane dimetatool, ethylene oxide adduct and propylene oxide adduct of bisphenol A,
Ethylene oxide and propylene oxide adducts of hydrogenated bisphenol A, polyethylene glycol,
Examples include polypropylene glycol and polytetramethylene glycol. Further, tri- and tetraols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol may be used in combination.

-3 above (as a dicarboxylic acid component having an hM group,
5-sodium sulfoisophthalic acid, 5-potassium sulfoterephthalic acid, 2-sodium sulfoterephthalic acid,
Examples include 2-potassium sulfoterephthalic acid.

In addition, the above hydrophilic polar group-containing organic diisocyanate is
It can be obtained by reacting a trifunctional or more functional polyisocyanate compound with a compound having a hydrophilic polar group.

As the above-mentioned polyisocyanate compounds, the trifunctional product name Desmod Shikaku (manufactured by Bayer AG) and the product name Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) are known, but in general, polyfunctional polyisocyanate compounds are not known as polyols. It is obtained by addition reaction with polyisocyanate.

Polyols include propylene glycol, glycerol, trimethylolpropane, pentaerythritol,
Examples include sorbitol. Examples of the polyisocyanate include tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, naphthylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, and lysine diisocyanate. It will be done.

-COO to the above trifunctional or higher functional polyisocyanate compound
To introduce M group, have -COOM group in one molecule,
What is necessary is just to react the compound which has active hydrogen which can react with -NGO group with a trifunctional or more functional polyisocyanate compound. As a result, two or more -
A compound having an NGO group and a -C00h group (C
OOl'l group-containing diisocyanate) is obtained.

Examples of the compound having a -COOM group in one molecule and an active hydrogen capable of reacting with the -NGO group include the following.

These compounds undergo an addition reaction with a trifunctional or higher functional polyisocyanate compound, for example, as shown in the following reaction formula.

(In the reaction formula, R-NGO represents a trifunctional or more functional polyisocyanate compound.) In order to introduce SO3M groups, one molecule must have 1303M groups and be capable of reacting with -NGO groups. A compound having active hydrogen may be reacted with a trifunctional or higher functional polyisocyanate compound. As a result, a compound (SO3M group-containing diisocyanate) having two or more -NGO groups in one molecule and -S(hM group) is obtained.

Examples of the compound having one 3O,1M group in one molecule and an active hydrogen capable of reacting with the -NCO group include the following.

These compounds undergo an addition reaction with a trifunctional or higher functional polyisocyanate compound, for example, as shown in the following reaction formula.

(In the reaction formula, R-NGO represents a trifunctional or more functional polyisocyanate compound.) To introduce the -O303M group, the reaction product of a trifunctional or more functional polyisocyanate compound and H, +SO,
It may be neutralized with OH, KOH, etc. By this, it has two or more -NGO groups in one minute character, and -080,M
A compound having a group (O3O+M group-containing diisocyanate) can be obtained, for example, as shown in the following reaction formula.

R-NCO+ H2SO4→ 1l-NHCO-O2
0,)IR-N)ICO-O3OJ + Na0H
R-NHCO-O3OJa + HzO (In the reaction formula, R-NGO represents a trifunctional or higher functional polyisocyanate compound.) To introduce the PO(OM')z group, a trifunctional or higher functional polyisocyanate compound and The reaction product with HzPOs is
It may be neutralized with aOH, KOFI, etc. by this,
For example, it can be obtained as shown in the following reaction formula.

R-NCO+ HsPO3R-NHCOI(OH)zR
-NHCOI(OH)z + 2 Na0F1R-NH
CO-1 ((ONa)z + 2H20 (in the reaction formula, R
-NGO represents a trifunctional or more functional polyisocyanate compound. ) Furthermore, the -C00M group can also be introduced by using a hydrophilic polar group-containing organic diamine, that is, a C00M group-containing organic diamine as a raw material.

Examples of the C00M group-containing organic diamine include aliphatic or alicyclic diamines and acid anhydrides as shown by the general formula (wherein R1 and R4 represent hydrocarbon groups having 2 to 12 carbon atoms). Molar reactants and their alkali metal salts are included. As the aliphatic or alicyclic diamine, tetramethylene diamine, hexamethylene diamine, 1,3-diaminomethylcyclohexane, 1,4-diaminomethylcyclohexane, 4,4-diaminodicyclohexylmethane, isophorone diamine, etc. are used. It is particularly preferable to use isophorone diamine. In addition, examples of the acid anhydrides include succinic anhydride, maleic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, and 4-methyl-C2,3,6-tetrahydrophthalic anhydride. etc.

On the other hand, as a specific example of the method (2) above, for example, (
A) CICH2CO0M, CICToCH2SO
3M, ClCH2CH20503M.

Contains a hydrophilic polar group and chlorine in the molecule, such as CICHzPO(OM')z (where M is a hydrogen atom or an alkali metal atom, and M is a hydrogen atom, an alkali metal atom, or a hydrocarbon group) The compound and the polyurethane-urea resin having a polyfunctional 10H group are mixed in dimethylformamide, in which both components are soluble.
By dissolving in a solvent such as dimethyl sulfoxide and dehydrochlorination reaction between 10H group and chlorine in the presence of dehydrochlorination agents such as amines such as pyridine, picoline, triethylamine, and epoxy compounds such as ethylene oxide and propylene oxide. There is a method of introducing a hydrophilic polar group. The reaction formula is as follows.

(A-1) RPLIU-OH+ CICH2CO0M → Rp
uu-OCHzCOOM + HCI (A-2) RPLIU-OH+ CICHzCHzSOJ→Rru
u-OCHzCFIzSOsM + HCI (A-3) Rpuu-OH+ CICHzCHJSOJ→Rruu
-OCHzC'H2O5O+M + )IcI(A-4
) RPLILI-OH+ CICHzPO(OM'h
→RPuu-OCHzPO(OM')z + HCI(
However, RPLILI represents polyurethane-urea resin. ) Although some by-products are produced, it can also be synthesized by the following method. That is, (B) HOCIhCOOM, HOCHzCHgS
OJ, HOCHzCHzO5OJ.

HOCHzPo (OM")2 and a diisocyanate compound, such as 4.4'-diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, are reacted in equimolar amounts, and one of the -NGO groups of the diisocyanate and A reaction product is obtained by reaction with the 10H group in the above compound.Next, by reacting the 10H group of the polyurethane-urea resin with the remaining 1NCO group, a hydrophilic polar group is introduced. A polyurethane-urea resin is obtained.The reaction formula is as follows.

(B-1) OCN-R''-NGO+HOCHzC00M→0CN-
R”-NCOOCIhCOOMRPULI-OH+ 0
CN-R”-NCOOCH2COOM-1 → RPLI
U-OCONH-R”-NCOOCH2C00M(B-
2) OCN-11”-NCO+ HOCHlCIhSOJ-
−→ 0CN-R”-NCOOC11,CI(,SO,
MRruu-OH+ 0CN-R"-NCOOCH2C
H2SO3M--→ Rpuu-OCONH-R"-N
COOCHgCHzSOJ(B-3) OCN-R″-NCO+ HOCH2CH20S03M
--→ 0CN-R"-NCOOCH, CH2O503
MRCH2O5O3+ QCN-R″-NCOOCFI
zCH20SOJ-1 → RPULI-OCONH-R
”-NCOOCIIZCH20S03M(B-4) OCN-R”-NGO+ l(OCLPO(OM')
z-→ 0CN-R"-NCOOCHzPO(OM'
)zRruu-OR+ 0CN-R"-NCOOCH
zPO(OM')z-→ RPULI-0CONH-R
”-NCOOCHZPO(OM')z (However, RPuu
represents a polyurethane-urea resin, and R'' represents a divalent hydrocarbon group.) In the above manner, -000M group, -3O,M group, -0303M group, -PO(OM')i group, respectively. can be incorporated into polyurethane-urea resins.

In the magnetic recording medium according to the present invention, a polyurethane-urea resin used as a binder for a magnetic paint contains a -COOM group, a -3OJ group, a -0503M group, or a -COOM group. -000M group, -303M group, -0503M group.

Two types of hydrophilic polar groups can be introduced as follows.

(I) A compound having -COO group in the raw material of polyurethane-urea resin, -5O,M group, -05OJ group, -
PO(OM') contains a compound having any of the z groups, and at the same time as the polyurethane-urea resin is produced, these -COOM groups, -5OffM groups, -0303M groups,
- A method of introducing any of the PO(OM')z groups.

(If) By modifying the 10H group present in the side chain or terminal of the polyurethane-urea resin that has already been synthesized,
-000M group and -303M group, -05O,M group,
- A method of introducing either of two PO(OM'') groups.

(III) 100% in the raw material of polyurethane-urea resin
A compound containing a 0M group is mixed in, and the terminal or side chain OH group of the resulting C00M group-containing polyurethane-urea resin is modified to form a -503M group, -050
A method of introducing either a 3M group or a -PO(OM')z group.

(IV) In the raw material of polyurethane-urea resin,
-303M group obtained by mixing a compound containing any one of M group, -O3OffM group, and -PO(OM')z group.

A method of introducing a C00M group by modifying the terminal or side chain OH group of a polyurethane-urea resin containing a -03OJ group or two -PO(OM') groups.

For example, in the case of method (1), -5O,M group.

A long chain polyester diol containing -osO, M group or two -PO(OM''') groups is used as a part of the long chain diol, and a short chain diol containing -C00M group (e.g. dimethylolpropionic acid) is used as a part of the long chain diol. A polyurethane-urea resin may be synthesized by reacting the mixture with an organic diisocyanate in advance to prepare an isocyanate group-terminated prepolymer, and then adding an organic diamine to extend the chain and introduce a urea bond.

In addition, in the case of method (II), a -COOM group is first introduced into the 10H group existing in the side chain or terminal of the polyurethane-urea resin that has already been synthesized, and then a -COOM group is introduced into the remaining 1OH group. 3O,M group, -oso3M group, -p.

Any one of the (OM')z groups may be introduced.

-COOM group and -3OffM group by the above-mentioned method,
-0 kinds of hydrophilic polar groups can be easily introduced into the polyurethane-urea resin.

The amount of hydrophilic polar groups introduced into the polyurethane-urea resin used as a binder is such that the sum of -C00M groups and other polar groups is 0.01 to 1.5 m mo/! It is preferably 7g, more preferably 0.01 to 0.5
It is in the range of IIllol/g. Here, -C00
The amount of M group introduced is preferably 0.01 to 0.5 mmoA/g. If it is less than 0.01 mmo17g, the dispersibility effect will be insufficient, and if 0.5mmoβ7g
If it exceeds this, the viscosity of the paint will increase, resulting in deterioration of workability and deterioration of the surface properties of the resulting magnetic recording medium. On the other hand, the amount of other polar groups introduced is o, ooimmo
j! /g or more is preferable, O,OOlmmo
j! If it is less than /g, the effect of preventing increase in paint viscosity will be insufficient. Furthermore, the sum of the introduced amounts of hydrophilic polar groups consisting of the C00M group and other polar groups is 0,01
m mail/g, a sufficient effect on the dispersibility of the ferromagnetic powder will not be observed, and if the amount of the hydrophilic polar group introduced is less than 1.5 m mail/g. If it exceeds ommoA/g, intermolecular or intramolecular aggregation tends to occur, which not only adversely affects dispersibility, but also causes selectivity with respect to the solvent, and there is a possibility that ordinary general-purpose solvents cannot be used.

Further, the above-mentioned polyurethane-urea resin has an average molecular weight of 2,000 to 60,000, more preferably 5,000 to 4,000.
Preferably, it is in the range of 0000. If the number average molecular weight is less than 2,000, the coating film-forming ability of the resin will be insufficient, and if the number average molecular weight exceeds 60,000, problems may occur during paint manufacturing processes such as mixing, transferring, and coating. be.

The aforementioned polyurethane-urea resin can be used with other thermoplastic resins,
It can be used in combination with thermosetting resins or reactive resins.

The thermoplastic resin has a softening temperature of 150°C or less,
The average molecular weight is 10,000 to 200,000 and the degree of polymerization is approximately 2.
00 to about 20,000, such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer.

Vinyl chloride-vinyl acetate-maleic acid copolymer.

Vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-vinylidene chloride copolymer, methacrylic ester- styrene copolymer,
Thermoplastic polyurethane resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyamide resin.

Polyvinyl butyral, cellulose derivatives, styrene
Synthetic rubber resins such as butadiene copolymers and polyester resins include polybutadiene.

Examples of thermosetting resins or reactive resins include phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea-formaldehyde resins, silicone resins, acrylic reactive resins, and epoxy resins. Polyamide resin, nitrocellulose-melamine resin.

Mixtures of high molecular weight polyester resins and isosifnate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanate.

Examples include polyamine resins and mixtures thereof. Among these, it is desirable to use in combination with those that have good dispersibility in ferromagnetic powder.

In the magnetic recording medium of the present invention, the magnetic layer is formed by coating the surface of the non-magnetic support with a magnetic paint prepared by, for example, dispersing ferromagnetic powder in the above-mentioned binder and dissolving it in an organic solvent.

Here, as the ferromagnetic powder used in the present invention, any ordinary magnetic powder can be used. Therefore, usable ferromagnetic powders include ferromagnetic iron oxide particles, ferromagnetic chromium dioxide, ferromagnetic alloy powders, hexagonal barium ferrite particles, iron nitride, and the like.

The above-mentioned ferromagnetic iron oxide particles are those in which the value of
1.50), magnetite (peso4.
1.33) and their isosolutes (FeOx, 1.33
<X<1.50). Furthermore, cobalt may be added to these ferromagnetic iron oxides for the purpose of increasing coercive force. There are two types of cobalt-containing iron oxide: doped type and deposited type.

The above-mentioned ferromagnetic chromium dioxide may include CrO2 or Ru for the purpose of improving the coercive force thereof.

A material to which at least one of Sn, Te, Sb, Fe, Ti, V, Mn, etc. is added can be used.

Examples of the ferromagnetic alloy powder include Fe, Co, and Ni.

Fe-Co, Fe-Ni, Fe-Co-Ni, C.

-Ni, Fe-Co-B, Fe-Co-Cr-B.

Mn-B i, "Mn-Al1. Fe-Co-V
etc. can be used, and A/! can be used to improve various properties of these. , Si, Ti, Cr, Mn, Cu, Zn, and other metal components may be added.

In addition to the binder and ferromagnetic powder, the magnetic layer also contains additives such as a dispersant, a lubricant, an abrasive, an antistatic agent,
Rust inhibitors and the like may also be added.

The above-mentioned dispersants (R-wetting agents) include caprylic acid, capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid,
Fatty acids with 12 to 18 carbon atoms such as lylunic acid and stearolic acid (R?C00)l, R? (alkyl or alkenyl group having 11 to 17 carbon atoms), metal soaps consisting of alkali metal salts (such as LtI Na+) or alkaline earth metal salts (Mg, Ca, Ba) of the above fatty acids, amides of the above fatty acids , polyalkylene oxide alkyl phosphate ester, trialkyl polyolefin oxy quaternary ammonium salt (alkyl has 1 to 5 carbon atoms, olefin is ethylene, propylene, etc.), and the like. In addition, higher alcohols having 12 or more carbon atoms, sulfuric esters, etc. can also be used. These dispersants are added in an amount of 0.5 to 20 parts by weight per 100 parts by weight of the binder.

Examples of the lubricant include dialkyl polysiloxane (alkyl has 1 to 5 carbon atoms) and dialkoxypolysiloxane (alkoxy has 1 to 4 carbon atoms).

Silicone oil such as monoalkylmonoalkoxypolysiloxane (alkyl has 1 to 5 carbon atoms, alkoxy has 1 to 4 carbon atoms), phenylpolysiloxane, fluoroalkyl polysiloxane (alkyl has 1 to 5 carbon atoms), graphite Conductive fine powder such as molybdenum disulfide, tungsten disulfide, etc., inorganic fine powder such as polyethylene, polypropylene.

Polyethylene vinyl chloride copolymers, fine plastic powders such as polytetrafluoroethylene, α-olefin polymers, unsaturated aliphatic hydrocarbons that are liquid at room temperature (compounds in which an n-olefin double bond is bonded to the terminal carbon, carbon number about 2
0), fatty acid esters (monoesters, diesters) consisting of fatty acids with 12 to 22 carbon atoms and alcohols with 3 to 22 carbon atoms.

It may be any triester, or even a higher polyfunctional polyester. ), fatty acids or their metal salts, fatty acid amides, fatty alcohols or their alkoxides, aliphatic amines, polyhydric alcohols, sorbitan esters, manniratan esters, sulfurized fatty acids, aliphatic mercaptans, perfluoroalkyl ethylene oxides, perfluoropolyethers class, higher alkyl sulfonic acids or their metal salts, perfluoroalkyl sulfonic acids or their ammonium salts or their metal salts, perfluoroalkyl carboxylic acids or their metal salts,
Fluorocarbons etc. can be used. These lubricants are added in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder.

The above-mentioned abrasives are commonly used materials such as fused alumina, silicon carbide, chromium oxide (Crt(h), corundum, artificial corundum, diamond, artificial diamond, garnet, emery (main components: corundum and magnetite), etc.). These abrasives have a Mohs hardness of 5 or more and an average particle size of 0.05 to 5μ, particularly preferably 0.1 to 2μ.These abrasives is 0.5 to 20 parts by weight per 100 parts by weight of binder.
It is added in a range of parts by weight.

The antistatic agent mentioned above is carbon black.

Conductive fine powder such as carbon blank graft polymer,
Natural surfactants such as saponin, nonionic surfactants such as alkylene oxide, glycerin, and glycidol, and higher alkylamines.

Quaternary ammonium salts, pyridine and other heterocycles,
Cationic surfactants such as phosphoniums, carboxylic acids,
Anionic surfactants containing acidic groups such as sulfonic acid, phosphoric acid, sulfuric acid ester groups, and phosphoric ester groups, amino acids,
Aminosulfonic acids.

Ampholytic activators such as sulfuric acid or phosphoric acid esters of amino alcohols are used. The above conductive fine powder is added in an amount of 0.2 to 20 parts by weight, and the surfactant is added in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the binder. These surfactants may be added alone or in combination.

Although these are used as antistatic agents, they are sometimes used for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids.

As the rust preventive agent, phosphoric acid, sulfamide, guanidine, pyridine, amine, urea, zinc chromate, calcium chromate, strontium chromate, etc. can be used, but in particular, dicyclohexylamine nitrite,
Volatile rust inhibitors (amine , an inorganic acid salt or an organic acid salt such as an amide or an imide), the rust prevention effect is improved. These rust inhibitors are used in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the ferromagnetic fine powder.

The constituent materials of the magnetic layer described above are prepared as a magnetic paint by dissolving it in an organic solvent, and are applied onto a non-magnetic support.
Solvents for the magnetic paint include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and glycol monoethyl acetate, glycol dimethyl ether, and glycol monoethyl ether. Glycol ethers such as ether and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene,
Aliphatic hydrocarbons such as hexane and heptane, methylene chloride, and ethylene chloride.

Examples include chlorinated hydrocarbons such as 4fHI, chloroform, ethylene chlorohydrin, and dichlorobenzene.

The material of the non-magnetic support to which these constituent materials are coated may be any material that is normally used in this type of magnetic recording medium, such as polyethylene terecrate, polyethylene-2,6-naphthalate, etc. polyesters such as polyethylene, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, cellulose acetate propionate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polycarbonate, Polyimide.

Plastics such as polyamide and polyamide-imide, non-magnetic metals such as aluminum, copper, tin, zinc or non-magnetic alloys containing these, light alloys such as aluminum alloys and titanium alloys, ceramics, and pottery.

Ceramics such as porcelain, single crystal silicon, and paper.

Baryta or polyethylene, polypropylene.

Paper such as paper coated with or laminated with an α-polyolefin having 2 to 10 carbon atoms such as an ethylene-butene copolymer can be used. The forms of these non-magnetic supports are as follows:
Film, tape, sheet.

It may be a disk, card, drum, etc.

[Effect]

As mentioned above, -COO1'l group and -3OJ are present in the molecule.
By using a polyurethane-urea resin into which any of the group, -oso, h group, and PO(OM')z group is introduced as a binder, the affinity for magnetic powder is greatly improved, and ultrafine particles can be obtained. Even magnetic powder or magnetic powder with a large amount of magnetization is well dispersed.

In addition, especially in conjunction with the -CO group, -3o, M group, -030
By introducing either the 3M group or the PO(OM')g group, the viscosity characteristics of the binder can be improved.

Furthermore, by using a polyurethane-urea resin as a binder, it is possible to significantly improve the thermal properties, anti-blocking properties, and durability of the magnetic layer, which has great advantages in the manufacturing process.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

First, a polyurethane-urea resin into which a hydrophilic polar group was introduced was synthesized by the method described in this specification. Tables 1 and 2 show the properties of the synthesized polyurethane-urea resin.

(Leaving space below) 1" Ray magnetic coating composition Ferromagnetic powder 100 parts by weight (specific surface area 35 n (/g, Co adhesion 7 FezO+) Vinyl chloride-vinyl acetate copolymer 10 parts by weight Binder 1 10 parts by weight Lubricant (silicone oil) 0.5 parts by weight Dispersant (lecithin) 0.5 parts by weight Abrasive agent (crzoz) 2 parts by weight Antistatic agent (carbon) 2 parts by weight Rust inhibitor (butyl stearate) 0.5 parts by weight 110 parts by weight Methyl ethyl ketone 50 parts by weight Toluene
50 parts by weight The above composition was mixed in a ball mill for 48 hours, filtered with a filter, 3 parts by weight of a curing agent (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronet L) was added, and the mixture was further mixed for 30 minutes. 16μ
The film was coated onto a polyethylene terephthalate film having a thickness of m so that the film thickness after drying was 6 μm. Next, after performing a magnetic field orientation treatment, it was dried and wound up. This was calendered and then cut into 1/2 inch width to produce sample tapes.

2 to 19 Sample tapes were prepared in the same manner as in Example except that Binder 2 to Binder 9 were used in place of Binder 1 in the composition of Example 1.

+1~'9 In the composition of Example 1, binder 10~ was substituted for binder 1
A sample tape was prepared in the same manner as in Example 1 except that binder 18 was used.

Surface gloss, powder removal, paint viscosity, and adhesion were measured for each sample tape obtained.

Note that the above surface gloss is based on the glossy needle (GLO3S METE).
R) under the conditions of an incident angle of 60° and a reflection angle of 60°. Further, powder falling was evaluated by visually observing the amount of falling powder on the head drum, guide, etc. after running the shuttle 100 times for 60 minutes, and using a point deduction method (-5 to 0). The paint viscosity is B
The values shown are those measured using a No. 4 rotor at 30 rotations using a type rotational viscometer. Adhesive properties were determined by wrapping a sample tape around a reel and leaving it for 24 hours at a temperature of 40°C and a humidity of 80%, and visually evaluating the degree of peeling of the sample tape.
It was scored on a 10-point scale, and the better the adhesive properties, the lower the score.

The measurement results are shown in Tables 3 and 4.

(The following is a blank space) As is clear from the results in Tables 3 and 4, each example according to the present invention has excellent surface gloss, powder removal, and adhesive properties. It can be seen that the paint has low paint viscosity and excellent workability.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
-C00M group is introduced into the molecule of polyurethane-urea resin, -503M group, -oso3M group.

- Since either of the two PO(OM') groups is introduced and used as a binder, it shows high affinity for magnetic powder,
Even if the magnetic powder is made into ultrafine particles or has a large amount of magnetization, the dispersibility will be good.

Furthermore, the polyurethane-urea resin used as the binder has excellent heat resistance and adhesive properties, so it is possible to significantly improve the thermal properties, blocking resistance, and durability of the magnetic layer.

Therefore, the properties of the coating film when formed as a magnetic layer are improved, resulting in a magnetic recording medium with extremely excellent durability, surface properties, and electromagnetic conversion characteristics.

In addition, polyurethane-urea resin easily dissolves in general-purpose solvents, and paints containing this binder have low viscosity and are easy to handle, making them excellent in terms of workability when forming coatings. have characteristics.

Patent Applicant: Sony Corporation Agent, Patent Attorney: Kodo Kowa, Sakae Enso - Procedural Principal Hosei (spontaneous) May 11, 1985, 1986 Patent Application No. 289883 2, Title of Invention: Magnetic Recording Medium 3 , Relationship with the case of the person making the amendment Patent applicant address 6-7-35 for solidified products for parts Tokyo Name (2
18) Sony Corporation Representative Ohga
Norio Spontaneous Agent (Butyl Stearate) 0.5 parts by weight'' Amendment 7, and the description of ``Surface Area'' on page 3, line 18 of the Specification of Contents of Amendment is amended to ``Surface Properties''.

From line 5 to line 6 of page 6 of the specification, the statement ``shows high affinity and improves dispersibility'' is replaced with ``shows high affinity and improves durability and dispersibility.'' ,” is corrected.

The statement "polyethylene glycol" on page 10, line 13 of the specification is amended to "polyethylene ether glycol."

On page 43, line 14 of the specification, the statement ``Good dispersion.'' was replaced with ``Good dispersion, and powder falling was reduced.''
and correct it.

On page 47, line 11 of the specification, the description ``Rust inhibitor (0.5 parts by weight of butyl stearate)'' has been changed to ``Lubricating.

that's all

Claims (1)

[Claims] A magnetic recording medium in which a magnetic layer mainly composed of ferromagnetic powder and a binder is formed on a non-magnetic support, wherein the binder has -SO_3M group, -OSO_3M group in the molecule.
At least one of the groups, ▲ mathematical formulas, chemical formulas, tables, etc. .) A magnetic recording medium characterized by containing a polyurethane-urea resin having the following properties.