JPS63137916A - Binder and magnetic recording material - Google Patents

Abstract

PURPOSE:To obtain a binder for magnetic recording materials, having excellent dispersibility of magnetic materials, adhesivity to substrates, calendering property, etc., and suitable for video tapes, magnetic cards, etc., by reacting a specific polyol with an organic polyisocyanate. CONSTITUTION:(A) A polyol, consisting of (i) a high polymer polyol having 200-2,000 equivalent, e.g. polycaprolactone polyol, etc., (ii) a low-molecular polyol, e.g. ethylene glycol, etc., (iii) a carboxyl group-containing urethane- modified diol, prepared by reacting dimethylolpropionic acid with tolylene diisocyanate and containing 0.1-60 equiv.% component (iii) and 10-50 equiv.% component (ii) is blended with (B) an organic polyisocyanate, e.g. xylylene diisocyanate, etc., and a magnetic substance, e.g. iron oxide, etc., is blended therewith. A solvent, if desired, is added and the resultant blend is applied to a substrate to afford the aimed binder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to binders and magnetic recording materials.

[Conventional technology]

Conventionally, polyurethane resins obtained by reacting organic polyisocyanates with polyol components consisting of high-molecular polyols, low-molecular polyols, and dimethylolpropionic acid have been known as binders for magnetic recording materials (for example, JP-A-59-148127). Public bulletin).

[Problem that the invention seeks to solve]

However, with the demand for high image quality and long recording times, video tapes are also required to have high recording density and high durability.
A binder with excellent dispersibility and adhesion to the substrate ester film is needed. [Means for solving the problem] The present inventors have developed a binder for magnetic recording materials with improved adhesion. As a result of extensive research into binders and recording materials, the present invention was arrived at.

That is, the present invention provides a polyurethane resin made of a polyol (5) consisting of a high molecular weight polyol (A3) of -9200 to 2000, a low molecular weight polyol (A2) and a carboxyl group-containing urethane-modified diol (A3), and an organic polyisocyanate n. (C) A binder for magnetic recording materials (first invention) and an equivalent weight of 200
A magnetic recording material consisting of a polyurethane resin (C) consisting of a polyol 8 consisting of a ~2000 high molecular polyol (A3), a low molecular polyol (A2) and a carboxyl group-containing urethane-modified diol (A3) and an organic polyisocyanate (B). A magneto-electric recording material (second invention) characterized in that it contains a binder and a magnetic material.

Examples of the carboxyl group-containing urethane-modified diol in the present invention include an OH-terminated prepolymer of a carboxyl group-containing diol and an organic polyisocyanate.

Carboxyl group-containing diols include aliphatic diols, such as dimethylolpropionic acid (abbreviated as DMPA).
and aromatic ones such as 4,4-bis(hydroxyphenyl)butyric acid, 4,4-bis(hydroxyphenyl)valeric acid, and mixtures of two or more thereof. Among these, preferred is DMPA.

Examples of the organic polyisocyanate include aromatic polyisocyanates such as aromatic polyisocyanate (tolylene diisocyanate) (TDI), 4,4'-diphenylmethane diisocyanate*-) (MDI) i-based MD
I, 1,5-naphthylene diisocyanate, m- and/or p-xylylene diisocyanate (MDI
), 2.2'-silicondiphenyl-4-4'-diisocyanate, etc.]; non-aromatic polyisocyanates such as aliphatic diisocyanates [tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc.], alicyclic polyisocyanates Diisocyanates of the formula [hydrogenated TDI (hydrogenated tolylene diisocyanate), hydrogenated MDI (hydrogenated 4,4'-diphenylmethane diisocyanate).

isopropylidene bis(4-cyclohexyl isocyanate), isophorone diisocyanate (IPDI), etc.], aromatic polyisocyanate multimers (TDl, MD
dimers and trimers such as I).

Trimer of non-aromatic polyisocyanate and NCO-terminated urethane prepolymer of polyol and aromatic polyisocyanate [reactant of low-molecular-weight polyol and excess aromatic polyisocyanate, such as trimethylolpropane (1 mol),! : Reaction product of TDI (8 mol)] An NCO-terminated urethane prepolymer of a polyol and a non-aromatic polyisocyanate (a reaction product of a polyol such as a low-molecular-weight polyol and an excess of a non-aromatic polyisocyanate), etc.

Among these, preferred are IPDI and MDI.

and XDI, particularly preferred is IPDI
and MDI.

The carboxyl group-containing urethane-modified diol (in the formula,
X is an organic polyisocyanate fortress, and n is 1-10. ) can be shown.

In the above, if n is less than 1, the adhesion is insufficient and n
If it exceeds 10, the drying properties of the binder will deteriorate.

When producing a carboxyl group-containing urethane-modified diol, the NC010H equivalent ratio of the carboxyl group-containing diol and the organic polyisocyanate is usually 0.4 to 0.99.
, preferably 0.5 to 0.95.

The above reaction can be carried out in the presence or absence of a solvent inert to isocyanate groups.

This solvent is an ester solvent (ethyl acetate).

butyl acetate, etc.), ethereal solvents (dioxane, etc.).

(tetrahydrofuran, etc.), ketone solvents (cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aromatic hydrocarbon solvents (toluene, xylene, etc.), and mixed solvents of two or more of these solvents.

The reaction temperature is usually 40 to 180°C, preferably 60 to 1
The temperature is 10°C.

In order to accelerate the reaction, catalysts used in ordinary urethane reactions, such as tin-based catalysts (trimethyltin urate, trimethyltin hydroxide,
Dimethyltin dilaurate.

Dibutyltin dilaurate, stannath octoate, etc.), lead-based catalysts (red oleate, red 2-ethylhexoate, etc.), etc. can also be used.

Examples of the polymer polyol (3) include polyether polyols and polyester polyols. Examples of the ether polyol include low-molecular glycols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.) and low-molecular triols (glycerin, trimethylone propane).

hexanetriol, etc.), alkylene oxides (alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide) adducts and ring-opening polymers of alkylene oxides. Specifically, polyethylene glycol.

Contains propylene glycol and polytetramethylene glycol.

t'c=tr The polyester polyol is a combination of a polycarboxylic acid (aliphatic polycarboxylic acid such as adipic acid, maleic acid, trimerized linoleic acid; aromatic polycarboxylic acid such as phthalic acid) and a low molecular weight preol or polyether posiol. Condensed polyether podiol containing terminal hydroxyl groups; polycaprolactone polyol For example, based on an initiator [glycol (ethylene glycol), triol, etc.], (substituted) caprolactone (ε-caprolactone, α-methyl-ε-caprolactone, α-methyl-ε-caprolactone, Polyols produced by addition polymerization of ε-methyl-, ε-caprolactone, etc.) in the presence of catalysts (organometallic compounds, metal chelate compounds, fatty acid metal acylations, etc.) and cyclic dicarboxylic acid-modified polycaprolactone polyols (Special application) 61-78920)
can be given.

Also, polymer polyols, polycarbonate polyols and polybutadiene polyols can be used.

Among these, preferred are polycaprolactone polyol and condensed polyester polyol.

A polymer containing 50 or more by weight of a compound selected from the group consisting of cyclic dicarboxylic acid modified polycaprolactone polyol and polytetramethylene glycol? It is a diol.

The light intensity of polymer bodiol (A3) is 200 to 2000
, preferably 250 to 1500.

The low-molecular polyol (A3) in the present invention includes low-molecular glycols (ethylene glycol, propylene glycol, 1.4-butanediol, etc.), low-molecular triols (glycerin, trimethylolpropane, hexanetriol, etc.), and tetrafunctional or higher-functional polyols (A3). low molecular weight polyols (sorbitol, sucrose, etc.).

These alkylene oxide low molar adducts (diethylene glycol, etc.) and phenols (phenol,
(bisphenol, etc.) and alkylene oxide low molar adducts (binuhydroxyethylbenzene, etc.). Among these, preferred are low molecular weight glycols.

The amount of (A3) is usually 0.1 to 60 parts, preferably 0.1 to 50 parts, based on the weight of flioh/I/(A). If the amount of (A3) is less than 0.14, the adhesion will be insufficient, and if it exceeds 60, the drying properties of the binder will be poor.

In the preol, (A3) is usually 0.1 to 70 equivalents, preferably 0.1 to 60 equivalents, and (At) is 5 to 8
It is 0 equivalent, preferably 10 to 50 equivalent. (A
3) is 5 wins! If it is less than 1, the film properties of the produced urethane resin tend to deteriorate and the dispersibility of the magnetic powder becomes poor. On the other hand, when (A2) exceeds 80 equivalents, the dispersibility of the magnetic material in the produced urethane resin decreases.

The equivalent weight to polyol is usually 100 to 1,600.

When the equivalent weight of fAl is less than 100, the resulting polyurethane resin becomes a brittle resin with poor film-forming properties, and is not sufficient as a binder for magnetic recording materials. On the other hand, the equivalent is 160
If it exceeds 0, the dispersibility of the magnetic material of the produced urethane resin will be reduced, the film strength will be insufficient, and the abrasion resistance, scratch resistance, hydrolysis resistance, etc. will be reduced.

In the present invention, the organic poly IC fucyanate ■ is as follows:
Examples include the same organic polyisocyanates as described in the section of the carboxy/L/group-containing urethane-modified diol. Preferred is MDI.

IPDI and TDI.

When (A) and 6 are reacted, the equivalent ratio of (3) to (3) is usually 0.6 to 1.5, preferably 0.8 to 1.2. If the equivalence ratio is less than 0.6 or more than 1.5, the polyurethane resin obtained by the reaction with (A) will have a low molecular weight and poor dispersibility, and the scratch resistance, abrasion resistance, and Hydrolysis resistance etc. tend to decrease.

The above reaction can be carried out in the presence or absence of a solvent inert to isocyanate groups.

This solvent is an ester solvent (ethyl acetate).

Butylacetate, etc.), ether solvents (dioxane, etc.), ethereal solvents (dioxane, etc.).

examples include tetrahydrofuran, etc.), ketone solvents (cyclohexanone, methylethylketone, methylisobutylketone, etc.), aromatic hydrocarbon solvents (toluene, xylene, etc.), and mixed solvents of two or more of these.

The reaction methods include a method in which AJ and N are charged in a reaction vessel all at once and reacted, a method in which AJ and N are separated and a multistage reaction is carried out, and a method in which AJ and N are mixed in advance in a heated continuation method. One example is a method of passing through an askneader and causing a reaction.

The reaction temperature is usually 40-180°C, preferably 60-80°C.
It is ℃. In order to accelerate the reaction, catalysts used in ordinary urethane reactions, such as tin-based catalysts (trimethyltin laurate, trimethyltin hydroxide, dimethyltin diurate, dibutyltin diworate, stannas outtoate, etc.), lead system catalyst (
red oleate.

Red 2-ethylhexoate, etc.) can also be used.

The resulting polyurethane resin (Q is a number average molecular weight of usually 3,00Q to 200.QQO, preferably 5.OQQ)
~150. It is QOO.

The molecular weight per carboxyl group is usually 1,000 to 2
00,Ql')Q, preferably s,ooo~150. O
Q O. The molecular weight of one carboxyl group is 1,
When it is less than 000, hydrolysis resistance decreases.

A polyurethane resin formed by reacting (3) and 6 (Q is used as a binder for magnetic recording materials, but if necessary, other polymeric materials commonly used for magnetic recording materials can be used in combination.

This polymeric material is polyvinyl chloride [Hinichloride J
L/-vinyl acetate copolymer (VYHH, manufactured by UCC; Enurec C1, Sekisui Chemical, etc.), vinyl chloride-vinyl acetate-vinyl alcohol copolymer (VACH, Eslec A, etc.), vinyl chloride-vinylidene chloride-acrylonitrile ( Saran, Asahi Dow), etc.).

Polyurethane type [urethane resin (manufactured by Nisten, Guttrich, etc.)], butadiene type [acrylonitrile-butadiene copolymer (/S Iker 1482, manufactured by Nippon Zeon, etc.), acrylonitrile-butanediene-styrene copolymer (A185), etc.], acrylic systems (such as various acrylic ester polymers).

Examples include nitrocellulose, phenoxy resin, and epoxy resin.

The binder for magnetic recording materials of the present invention can be made into a magnetic recording material (hereinafter sometimes referred to as magnetic paint) by containing the binder and a magnetic substance.

Examples of this magnetic material include iron oxide such as γ-Fe, 03(
γ-hematite), Crys (chromium trioxide) alloy-based magnetic materials such as Cor-Fe20s (
cobalt ferrite or cobalt-doped γ-iron oxide)
.

Examples include Fe-Co-Cr and pure iron Fe. In the present invention, especially the recent more finely powdered γ-
It is useful for Fe,03 (for example particles with a specific surface area of 40 m2/ji or more as measured by the BET method).

The magnetic material is magnetic powder, and its shape is usually granular or acicular. For example, if the diameter of the magnetic material is 0
．． 02 to 0.7Q, for example, major axis 0.2 to 0.7. The short axis is 0.02 to 0.1.

A crosslinking agent can be used in the magnetic paint to crosslink the polyurethane resin. Examples of the crosslinking agent include NGO-containing compounds and active hydrogen-containing compounds. NGO
The containing compound is polyisocyanate [modified MDI (
Millionate ME, manufactured by Hodogaya Chemical), 3.14'-dimethoxy-44'-diisocyanate, etc.) and NG
O-terminated prepolymer [polyisocyanate (TDl, M
DI, etc.) and polyols (low molecular polyols, polyether polyols, polyester polyols, etc.)
CO-terminated prepolymers, such as desmodules (manufactured by Bayer).

Coronet) L (manufactured by Nippon Polyurethane), etc. Active hydrogen-containing compounds include polyamines (tolylene diamine (TDA), 4,4'-diaminodiphenylmethane (MDA), 4,4'-diamino-3°8'-dichlorodiphenylmethane, etc.) and polyols (low molecular polyols, (polyether polyol, polyester polyol, etc.).

The amount of crosslinking agent added is usually θ~25 for polyurethane resin.
Weight factor, preferably 2 to 15 weight factor.

If the weight exceeds 26%, the flexibility of the film tends to decrease.

Other necessary dispersants (lecithin, anion.

Nonionic, cationic surfactants such as sodium dodecylbenzenesulfonate) and lubricants (higher fatty acid esters such as butyl stearate) can also be added.

A solvent is used in magnetic paint to adjust the viscosity.

Examples of this solvent include the same solvents as those described in the polyurethane resin production reaction, such as ester solvents (ethyl acetate, butyl acetate, etc.), ether solvents (dioxane, tetrahydrofuran, etc.), ketone solvents (cycloheyasanone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aromatic hydrocarbon solvents (toluene, xylene, etc.), and mixed solvents of two or more of these solvents can be used. Among these, preferred are mixed solvents of ketones and aromatic hydrocarbons.

The content of polyurethane resin (q) in the magnetic paint is usually 5 parts by weight or more, preferably 6 to 20 parts by weight, based on the weight of the paint. can be fully achieved.

The amount of magnetic material in the magnetic paint is usually 80 to 80% by weight, preferably 82 to 60% by weight.

The amount of solvent in the magnetic paint is usually 80-80% by weight, preferably 40-70% by weight.

The amount of other polymeric materials is usually 0 to 20% by weight, preferably 2 to 15% by weight.

The amount of other components (crosslinking agent, dispersant, lubricant, etc.) is usually 0 to 0.
8 parts by weight, preferably 0.01 to 2 parts by weight.

Binder is a method for manufacturing magnetic paint.

An example of a method is to mix the solvent and the magnetic material in advance using a premixer or the like, if necessary, and then disperse the mixture using a mixing/dispersing machine (ball mill or the like), followed by filtration.

This magnetic paint can be applied to a support film for magnetic recording media to create magnetic recording media (magnetic tape, etc.). Examples of the support film include films of paper, cellophane, acetate, polyester (PET), reinforced polyester, polyimide, and the like. Among these films, polyester film is often used.

When a magnetic coating is applied to a support film, the coating thickness is usually from several microns to several tens of microns. Application methods include coating methods such as doctor blade method and transfer printing method (gravure method, reverse roll method, etc.).

The film coated with the magnetic paint is then subjected to processes such as orientation, drying, surface processing, cutting, and winding to form a magnetic recording medium.

Generally, EFi recording media consist of a support film and a magnetic layer (magnetic binder), but those with an intermediate layer (undercoat layer) between the support film and the magnetic layer, There are also those that have magnetic layers on both sides, those that have magnetic layers with different magnetic properties stacked on top of each other, and those that have a protective layer provided on the magnetic layer.

〔Example〕

The present invention will be further explained below with reference to Examples.
It is not limited to this. Parts in Examples indicate parts by weight.

Example 1 1 mole of cyclic dicarboxylic acid-modified polycaprolactone diol having an equivalent weight of 1000, 1 mole of polytetramethylene glycol having an equivalent weight of 500, 8 moles of neopentyl glycol, and 0.1 l of a carboxyl group-containing urethane-modified diol.
A mixture of mol and 1 mol of 1,4-butanediol and TDI
6.1 mol was reacted to obtain polyurethane (C)HV IQ )t- having a slight hydroxyl group end. This is referred to as polyurethane resin (C1).

(Note) Carboxyl group-containing urethane-modified diol L1.
1: Urethane-modified diol τ made from 2 moles of DMPA and 11 moles of IPD.Using this (C1) as a binder, a mixture of the following composition was mixed in advance in a premixer, mixed in a ball mill, and dispersed to form a magnetic paint.3) It was created.

7-Fe, 03 fine powder IQO part polyurethane resin (CI) 2 parts Desmodule L
2 parts lecithin 1 part methyl ethyl ketone 75 parts toluene 75 parts This magnetic paint was applied onto a polyester film so that the coating thickness after drying was 5 μm and dried.

This is pressed using a press with a linear pressure of 200 kg and 80ff per minute.
! The film was calendered for 1 to 8 passes at a speed of . Also, the temperature at this time is 80°C. After calendering, the tape was cut into a tape width of 12.65 mm.

This is called a magnetic tape (E3).

Example 2 1 mole of cyclic dicarboxylic acid-modified polycaprolactone diol with an equivalent weight of 1000, 2.5 moles of neopentyl glycol, 0.0 of carboxyl group-containing urethane-modified diol 1
Polyurethane resin (C) HV4.3) tmfc which has a hydroxyl group end by reacting a mixture of 66 moles and 1.784 moles of ethylene glycol with 5.8 moles of ethylene glycol.

This is referred to as polyurethane resin (C).

In the composition of Example 1, polyurethane resin (CI) 20
A magnetic paint paste was obtained in the same manner as in Example 1, except that 20 parts of polyurethane resin (C2) was used instead of 20 parts, and a magnetic tape was made. This is called a magnetic tape (E2).

Example 8 1 mol of polycaprovaccinol with an equivalent weight of 1000,
1 mole of polypropylene glycol with an equivalent weight of 200.

0.08 of carboxyl group-containing urethane-modified diol 1
Polyurethane resin (C) HV3゜7) with a few terminal OH groups obtained by reacting a mixture of 75 mol and 0.9625 mol of ethylene glycol with 8 mol of MDI
I got it. This is referred to as polyurethane resin (C3).

In the composition of Example 1, polyurethane resin (C1)
Magnetic paint 3) was obtained in the same manner as in Example 1 except that 20 parts of polyurethane resin (C3) was used instead of 20 parts.
Created magnetic tape. This is called magnetic tape 3).

Comparative Example 1 5000f Litetwamethylene Glycol 2 mol, 1
．． A mixture of 8 moles of 6-hexanediol, 6 moles of DMPA O, and 1 mole of trimethylolpropane and TDI
7 moles were reacted to obtain a polyurethane resin (C) (V 7.2 ) having a slight terminal OH group and C0OH group. This polyurethane resin is referred to as a comparative example (C'+).

In the composition of Example 1, polyurethane m fat (C1)
A magnetic paint (rfs
) was obtained and a magnetic tape was created. This is magnetic tape (E
;).

Test Example 1 For the magnetic tapes obtained in Examples 1 to 8 and Comparative Example 1, test pieces were prepared according to the cross-cut test method (JIS K5400-79), and cellotape punching was performed. The results are shown in Table-1. The numerical value indicates the number of peeled pieces.

Also, the smaller the value, the better the adhesion force.

Table 1 [Effects of the Invention] The binder for magnetic recording materials and the magnetic recording material of the present invention are different from conventional binders (Japanese Patent Laid-Open No. 59-148127
It has superior adhesion to polyester films compared to the one disclosed in the publication. Therefore, even if magnetic tape is used repeatedly, its acoustic and recording characteristics will change.
Does not decrease.

Moreover, the binder and material of the present invention have extremely good dispersibility of magnetic substances. It also has excellent calendar properties. Therefore, it exhibits excellent effects as a binder for magnetic recording materials and as a magnetic recording material.

Claims (1)

[Claims] 1. High molecular weight polyol (A_1) having an equivalent weight of 200 to 2000
), for a magnetic recording material characterized by comprising a polyurethane resin (C) consisting of a polyol (A) consisting of a low-molecular polyol (A_2) and a carboxyl group-containing urethane-modified diol (A_3) and an organic polyisocyanate (B). binder. 2. The binder according to claim 1, wherein (A_3) is an OH-terminated prepolymer of a carboxyl group-containing diol and an organic polyisocyanate. 3. (A_3) is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) (In the formula, X is a residue of organic polyisocyanate, and n is 1 to
It is 10. ) The binder according to claim 1 or 2, which is a compound represented by: 4. The content of (A_3) is 0.1 based on the weight of (A)
60% of the binder according to any one of claims 1 to 3. 5. The number average molecular weight of (C) is 3000 to 200,000
The binder according to any one of claims 1 to 4. 6. High molecular weight polyol (A_
1) A magnetic recording material binder and magnetic material consisting of a polyol (A) consisting of a low-molecular polyol (A_2) and a carboxyl group-containing urethane-modified diol (A_3) and a polyurethane resin (C) consisting of an organic polyisocyanate (B). A magnetic recording material characterized by containing a substance.