JPS62201918A - Binder and magnetic recording material - Google Patents

Abstract

PURPOSE:To obtain a binder excellent in wet heat resistance, hydrolysis resistance and an ability of dispersing a magnetic substance, comprising a polyurethane resin obtained from a specified active hydrogen-containing compound component and an organic polyisocyanate. CONSTITUTION:A cyclic dicarboxylic acid-modified polycaprolactone polyol is obtained by reacting a polyalcohol with a cyclic dicarboxylic acid (anhydrie) or its dialkyl ester and epsilon-caprolactone or 1,6-hydroxycaproic acid or its ester. A polymer polyol (a) of an equivalent of 200-20,000, comprising at least 50wt% this polyol and optionally other high-molecular polyols, is mixed with a low- molecular glycol (b) and a compound (c) having a carboxyl group and an active hydrogen-containing group in the molecule, selected from among a hydroxy acid, an amino acid and a mercapto acid to obtain an active hydrogen-containing compound component (A). Component A is reacted with an organic polyisocyanate (B) to obtain a binder comprising a polyurethane resin having a MW of 1,000-50,000 per carboxyl group.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a binder and a magnetic recording material. [Prior Art] Conventionally, as a binder for a magnetic recording material, a polymer polyol and a carboxyl group and other There is a polyurethane resin made from an active hydrogen-containing compound component containing a compound having an active hydrogen-containing group, etc., and preisocyanate (
(Japanese Patent Application Laid-Open No. 59-148127).

[Problem that the invention seeks to solve]

However, this tape had poor heat and humidity resistance and insufficient durability.

[Means for solving problems]

The present inventors have arrived at the present invention as a result of extensive studies aimed at obtaining a binder for a magnetic recording material and a magnetic recording material that have excellent hydrolysis resistance and excellent dispersibility of magnetic substances.

That is, the present invention provides three amounts of 2QO to 2000 polycaprolactone polyols containing a cyclic dicarboxylic acid-modified polycaprolactone polyol (a).
An active hydrogen-containing compound component (A) consisting of a high-molecular-weight polyol (A2) and a compound (A3) having a carboxyl group and other active hydrogen-containing groups in the molecule; Polyisocyanate (B)
The polyurethane resin (C) from [Tazo] has a molecular weight per carboxyl group in (C) of 1. , OOO-50
.

The cyclic dicarboxylic acid-modified polycaprolactone polyol (a1) in the present invention includes a polyhydric alcohol; a cyclic dicarboxylic acid, its anhydride or its dialkyl ester; and a polyester from ε-caprolactone or l,6-oxycaproic acid or its ester. When polyol is added, it becomes white. This polio-/L/ (at) is JP-A-59
The polyester polyol described in Japanese Patent No. 179519 can be used.

The above-mentioned cyclic dicarboxylic acids, anhydrides or dialkyl esters thereof include phthalic anhydride; isophthalic anhydride; isophthalic acid; terephthalic acid; dimethyl and diethyl-esters of isophthalic acid, terephthalic acid and phthalic acid;
Methi/L/)tetrahydrophthalic anhydride, (Methi/L/)
) Hexahydroheptalic anhydride, methylhimic anhydride, etc. Preferred is isophthalic acid. The cyclic dicarboxylic acid may be used in combination with an aliphatic straight chain dicarboxylic acid if necessary.

Polyhydric alcohols include those with straight chains and side chains, such as ethylene glycol and propylene glycol;
, 3 - Another fly. 4-Butanediol.

2-Methyl-1,3-propanediol, 1.5-bentanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, hydroxypinocylate phosphate of neopentyl glycol/L/, 2,
Examples include 3.5-)limethylpentanediol. Preferred are polyhydric alcohols with side chains such as neopentyl glycol.

It is a hydroxypivalate ester of 2-methyl-1,3-propanediol and neopentyl glycol.

ε-caprolactone may be used in combination with other lactones (such as δ-valerolactone).

In (a), the amount of the reactive residue of ε-caprolactone or 1,6-oxycaproic acid or its ester is usually 40 to 95% by weight, but it may be other than this.

Cyclic dicarboxylic acid residue in (a1) (-oCOCO-)
The amount is usually 2% by weight or more, preferably 5 to 35% by weight.

In (a,), the molar ratio of cyclic dicarboxylic acid and polyhydric alcohol is usually 1:1.01 to 5. Preferably 1:1.
1 to 4. The molar ratio of cyclic dicarboxylic acid and ε-caprolactone is usually 1:3 to 50, preferably 1:3.5.
~40.

(a) can be synthesized by charging all the raw materials into a reaction vessel and heating, preferably in the presence of a ring-opening catalyst and an etherification catalyst. It is also possible to synthesize (ao) by mixing and heating a polyester polyol made from a polyhydric alcohol and a cyclic dicarboxylic acid synthesized in advance and polycaprolactone at a predetermined ratio and carrying out an ether exchange reaction. It can also be synthesized by thermally reacting an oxide and a lactone.

(a1) is -〇〇LO-, -cO-] (=CO-O!
It is a compound having a H-0AO-4) unit, for example, in the general formula C, L is a lactone residue, A is a polyhydric alcohol group,
where n is a cyclic dicarboxylic acid residue, n is 0 or 1 or more, and m is 1 or more.

The water e value of (at) is usually 10 to 15o1, preferably 1
5 to 100, and the acid value is usually 5 or less, preferably 1 to 1.
It is as follows.

Other polymeric polyols can be used together with (a1) if necessary. What about this polymer polyurethane?
Liete #4! Liol [low molecular glycols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.); low molecular triols (glycerin, trimethylone propane, hexanetriol, etc.); low molecular polyols with tetrafunctional or higher functionality (sorbitol, sucrose, etc.) or amines (alkanolamines, aliphatic
adducts of alkylene oxides (alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide) and ring-opening polymers of alkylene oxides). Specifically, polyethylene glycol, polypropylene glycol/L/
, polytetramethylene glycol.

Also, polyester polyols [terminal hydroxyl groups of polycarboxylic acids (aliphatic polycarboxylic acids such as adipic acid, ?leic acid, dimerized linoleic acid; aromatic polycarboxylic acids such as phthalic acid) and low-molecular-weight lyo-ρ or polyether polyols] Containing polyester polyol],
Polymer polyols and polybutadiene polyols can also be used. Among these, polyester/
L/polyol.

The content of the cyclic dicarboxylic acid modified polycaprolactone (a1) in the polymer polyol (A) is usually 50% by weight or more, preferably 80 to 100% by weight, particularly preferably 90 to 100% by weight. be. Content is 50 weight! When the amount is less than 50%, the dispersibility of the magnetic material decreases.

The equivalent weight of the polymer polyol (A1) containing (a,) is 20
0-2000, preferably 400-1500. If the equivalent weight is less than 200, the dispersibility of the magnetic material of the urethane resin obtained will be reduced, and the scratch resistance will also be reduced. In addition, when the equivalent weight exceeds 2000, the polyurethane resin obtained has good dispersibility in magnetic materials, abrasion resistance, 1iiit clutch property,
Hydrolysis resistance etc. decrease.

Examples of the compound (A2) having a carboxy/I/ group and other active hydrogen-containing groups in the molecule in the present invention include oxyacids, amino acids, and mercapto acids. This oxyacid usually has an equivalent weight of 40 to 400, for example, an oxyacid having one OE group and one C00Hi in the molecule (aliphatic ones, such as lactic acid; aromatic ones, such as benzyl i'9F). salicylic acid, p-oxybenzoic acid, β-oxynaphthoic acid, etc.), O
Oxyacids having one H group and a plurality of 000H groups, e.g. 2 to 4 (aliphatic ones such as malic acid, citric acid; aromatic ones such as 4-hydro-bovine isophthalate/I
/acids), oxyacids having two oH groups and one COOH group in the molecule (aliphatic ones such as dimethylolpropionic acid (DMPA); aromatic ones such as 4.
4- and 7(hydroxyphenyl)i acids, 4゜4-bis(
Hydroxyphenylene/I/) valeric acid, etc.) and mixtures of two or more of these ◎ Preferred among these are oxyacids having two 0) (groups and one COOH group, and particularly preferred) The material is DMPA.

Also, as an amino acid, there is an active hydrogen-containing group (NH2 group).

Amino acids that usually have an equivalent weight of 50 to 500 NH groups, such as neutral amino acids (amino acids having one carboxyl group and one amino group, such as glycine and alanine).

tyrosine, serine, synutein, etc.), acidic amine e (
Amino acids with two carboxyl groups and one amine group (e.g. aspartic acid, glutamic acid, etc.), basic amino acids (amino acids with one carboxyl group and two amino groups such as lysine, ornithine, arginine, etc.), and two or more of these A mixture of Among these, preferred are neutral amino acids and basic amino acids, and particularly preferred are basic amino acids.As for mercapto acids, the equivalent of active hydrogen-containing group (SH group) is usually 40 to 400, such as thioglyco −
/L/acid, thiodiglycol/L/acid, thiodipropionic acid, etc.

Two or more of these oxyacids, amino acids, mercapto acids, etc. can also be used in combination.

As the low molecular weight polio-/I/(^) in the present invention,
Low-molecular glycols (ethylene glycol, propylene glycol/I/11゜4-butanediol, etc.), low-molecular triols (glycerin, trimethylolpropane, heyazantriol, etc.), low-molecular polyols with tetrafunctional or higher functionality (sorbitol, M sugar, etc.) to).

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

In the active group-containing compound component (A), a low molecular polyol (A
, ) is usually 5 to 80 equivalents, preferably 10 to 50 equivalents. If (A2) is less than 5 equivalents, the film properties of the produced urethane resin tend to deteriorate and the dispersibility of the magnetic powder becomes poor. On the other hand, if (A2) exceeds 80 equivalent t%, the dispersibility of the magnetic material in the produced urethane resin decreases.

High molecular polyol/L/(4) *Low molecular polyol (A
The total equivalent weight in the active hydrogen-containing compound component consisting of 2) and the compound (A,) having carboxyl groups/groups and other active hydrogen-containing groups in the molecule is usually 100 to 1,600. (If the equivalent weight is less than 100, the resulting polyurethane resin will be a brittle resin with poor film-forming properties, and will not be sufficient as a binder for magnetic recording materials.On the other hand, if the equivalent weight exceeds 1600, the magnetic material of the resulting urethane resin will be dispersed.) The properties of the film decrease, film strength becomes insufficient, and abrasion resistance, scratch resistance, hydrolysis resistance, etc. decrease.

The polyisocyanate (B) in the present invention is an aromatic polyisocyanate such as an aromatic polyisocyanate (tolylene diisocyanate (TDI)).

4.47-cyphenylmethane diisocyanate CMDI
) modified tg MDI, 15-naphthylene diisocyanate.

m- and/or p Q silylene diisocyanate, 2,2'-dimethyldiphenylmethane-4,4'-diisocyanate, etc.), polymers of aromatic polyisocyanates (dimers and dimers such as TDl, MDI, etc.)
and NC of polyol and aromatic polyisocyanate
Reactant of O-terminated urethane premariner molecule polyol and excess aromatic polyisocyanate, such as trimethylolpropane (1 mol) and 'I'DI (3 mol/L/)
reactants].

Among aromatic polyisocyanates, preferred are T
DI and MDI.

In addition, non-aromatic polyisocyanates such as aliphatic diisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc.), alicyclic diisocyanates [hydrogenated TDI (hydrogenated tolylene diisocyanate), hydrogenated MDI (hydrogenated 4.47 NCO-terminated urethane prepolymer of non-aromatic polyisocyanate dimer and polyol and non-aromatic polyisocyanate (a reaction product of a polyol such as a low-molecular-weight polyol and an excess of non-aromatic polyisocyanate) can also be used.

(When reacting Al and (B), (B) and (5)
The equivalent ratio is usually 0.6 to 1.5, preferably OJ to 1.5.
It is 2. If the equivalence ratio is less than 0.6 or more than 1.5, the molecular weight of the polyurethane resin obtained by the reaction between O. Abrasion resistance, hydrolysis resistance, etc. tend to deteriorate.

The above reaction can be carried out in the presence or absence of RK which is inactive towards isocyanate groups.

This solvent is an ether solvent (ethyl acetate).

Butylacetate, etc.), ether solvents (dioxane, 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 methods include a method in which (4) and (B) are charged in a reaction container all at once and reacted, a method in which (A) and (B) are divided and subjected to a multistage reaction, and a method in which (A) is mixed in advance.
and FB) are passed through a heated continuous kneader to react.

The reaction temperature is usually 40 to 130'O, preferably 60 to 8
It is 0゛C. In order to accelerate the reaction, catalysts used in ordinary urethane reactions, such as tin-based catalysts (1-limethyltinlaure-1-), are used.

Trimethyltin hydroxide, dimethyltin dilaurate, dibutyltin dilaurate, stannath octoate, etc.), lead-based catalysts (red oleate, red 2-ethylhexoate-1, etc.), and the like can also be used.

The obtained polyurethane resin (C) has 1 carboxyl group
The molecular weight per piece is 1,000-50. Q 00,
Preferably 5,000 to 50,000, particularly preferably 1, o, ooo to so, o o o. When the molecular weight per carboxyl group is i, ooo,
Hydrolysis resistance decreases.

Polyurethane resin (C) obtained by reacting (5) with)
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 [chlorinated]
Blank vinyl-vinyl acetate copolymer (VYHH, manufactured by Uee; S-LEC C2 manufactured by Sekisui Chemical, etc.), vinyl chloride-vinyl acetate-vinyl alkonitrogen copolymer (VACH).

S-LEC A, etc.), vinyl chloride-vinylidene chloride-acrylonitrile (Saran, manufactured by Asahi Dow), etc.], polyurethane-based [urethane resin (Nisten.

Guttrich ring, etc.)] 2-butadiene type (acrylonitrile-butadiene co-x combination c Hiker 1432° Nippon Zeon ring, etc.), acrylonitrile-butanediene-styrene copolymer (A1.95'), etc.), acrylic type (
Examples include various ethyl acrylate polymers), nitrocellulose, phenoxy resins, and epoxy resins.

A magnetic recording material (hereinafter sometimes referred to as "magnetic paint") can be obtained by incorporating the binder for magnetic recording materials of the present invention with a magnetic material.

Examples of the magnetic material include iron oxides such as γ-Fe and O.

(γ-hematite), CrO, (chromium oxide), and alloy-based magnetic materials such as cor-r-Fe, 0. (
cobalt ferrite or cobalt-doped γ-iron oxide)
.

Examples include F6 Co Or T and pure iron Fe. In the present invention, especially the recent more finely powdered T.
-Magnetic materials useful for -FexOs (for example particles with a specific surface area of 40 mVN or more by the BE'I' method) are magnetic powders, which are usually granular and acicular in shape. The size of the magnetic material (μm) - For example, if the diameter is 0
．． 02 to 0.70, for example, the major axis is 0.2 to ρ, and the minor 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 NCO-containing compounds and active hydrogen-containing compounds. N.C.O.
The containing compound is polyisocyanate [modified MDI (
Millionaire) ME, Hodogaya Chemical), 3,3'-dimethoxy-4,47-diisocyanate, etc.) and NCO
The terminal pre is remer [polyisocyanate] (TDI,
MDI, etc.) and polyols (low molecular weight polyol/L/,
polyether polyol, polyester polyol, etc.)
L/L (manufactured by Bayer).

Colo-F)L (Japan Polyurethane iF), etc.) can be obtained. In addition, active hydrogen-containing compounds include polyamines [tolylene diamine (TDA), 4,4'-diaminodiphenylmethane (MDA), 4;4'-diamino-
3,37-cyclodiphenylmethane) and polyols (low-molecular polyols, polyether polyols).

terboliol, etc.) are failed.

The amount of crosslinking agent added is usually 0 to 25% to the polyurethane resin.
% by weight, preferably 2-15% by weight.

If it exceeds 25% by weight, the flexibility of the film tends to decrease.

Other dispersants (lecithin, anion) as necessary.

Nonionic t-cationic surfactants such as dodecylbenzene sulfonic acid sorter) and lubricants (higher fatty acid esters such as butyl stearate) may also be added.

For magnetic properties, a solvent is used to adjust the viscosity.

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

The content 1 of the polyurethane resin (C) in the magnetic paint is usually 5 weight molecules or more, preferably 10 to 4 weight molecules, based on the weight of the paint.
It is 0% by weight. , (C) in an amount of 5X or more, the object of the present invention can be fully achieved.

The amount of magnetic material in the magnetic paint is usually 30 to 80% 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 a magnetic recording medium to create a magnetic recording medium (magnetic tape, etc.). Examples of the support film include films of paper, cellophane, acetate, polyester (r:'r), reinforced polyester, polyimide, and the like. Among these films, polyester film is often used.

When a magnetic paint is applied to the 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.).

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

Magnetic recording media generally consist of a support film and a magnetic layer (magnetic binder), but there are also media that have an intermediate layer (undercoat layer) between the support film and the magnetic layer, and Some have magnetic layers on both sides, some have stacked magnetic layers with different magnetic properties, and some have a protective layer 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 Cyclic dicarboxylic acid modified polycaprolactone di-/L/1 mole having an equivalent weight of 425, polytetramethylene L/L/1 mole having an equivalent weight of 500
neopentyl glycol/l/1 mol, neopentyl glycol/I/
3 mol/L/, and DMPA O, 0625 mol and 1.
A mixture of 0.9175 mol of 4-butanedio-/L' and 5 mol of 'I'DI were reacted to obtain a polyurethane (Of(Vlo)) having a slight hydroxyl group end. This was designated as biliurethane resin (C1). - Using this (C8) as a binder, a mixture of the following composition was mixed in advance in a premixer and ball milled.

The2o, fine powder 100 parts Polyurethane resin (0,) 20 parts (88:12')
Copolymer Denumodhu/L/L 2 parts lecithin 1 part methyl ethyl ketone 75 parts toluene
75 parts of this magnetic paint was applied onto a polyester film to a coating thickness of 5 μm after drying and dried.

The film was calendered by passing it through a press machine 1 to 3 times at a linear pressure of 200 at a speed of 3 parts per 9.1 minutes.

Further, the temperature at this time was 80°C. After calendering, the tape was cut to a width of 12.65 mm.

This is called a magnetic tape (E,).

Comparative Example 1 A amount of 5oo polytetramethylene glyco-/I/2 mol, 1.6-hexanedio-/I/3 mol, DMPAo,
A mixture of 6 moles of trimethylolpropane and 1 mole of trimethylolpropane is reacted with 7 moles of TDI to form a slightly terminal OH group and COO.
Polyurethane resin having H group (Of(V 7.2
) was obtained. This polyurethane resin is referred to as Comparative Example (c',).

In the composition of Example 1, polyurethane resin (C1)2
A magnetic paint (:D',
) was obtained and a magnetic tape was created. This is magnetic tape (E
'1).

Test Example 1 A heat and humidity resistance test was conducted on the polyurethane resins obtained in Example 1 → and Comparative Example 1.

The results are shown in Table-1. Numerical values indicate retention rates. The retention rate shall be expressed as a percentage of (resin strength after test)/(resin strength before test). Resin strength: JISK-6
301, after molding with a No. 3 dumbbell, measurement is performed at a tensile rate of 30 α/min.

Table 1) M+oo: 100% Modular Ee: Elongation (
(at break) TS: represents breaking strength.

4"2" [Effects of the Invention] The binder for magnetic recording materials and the magnetic recording material of the present invention have superior heat and moisture resistance as compared to the conventional binder (Japanese Patent Application Laid-open No. 148127/1983).

Therefore, when using magnetic tape, the acoustic characteristics and recording characteristics of the magnetic tape are less susceptible to environmental changes such as temperature and humidity. Therefore, it is possible to obtain a magnetic tape with excellent durability and stable sound and image quality.

Moreover, the binder and material of the present invention have extremely good dispersibility of magnetic substances. Also wear resistant.

It also has excellent scratch resistance and calendaring properties.

Therefore, it exhibits excellent effects as a binder for magnetic recording materials and as a magnetic recording material.

Claims (1)

[Scope of Claims] 1. A high molecular polyol (A_1) with an equivalent weight of 200 to 2000 containing a cyclic dicarboxylic acid-modified polycaprolactone polyol (a_1), a low molecular polyol (A_2), and a carboxyl group and an active hydrogen-containing group in the molecule. An active hydrogen-containing compound component (A_3) consisting of a compound (A_3) having
) and an organic polyisocyanate (B) [and the molecular weight per carboxyl group in (C) is 1,000 to 50,000]. Binder for magnetic recording materials. 2. The content of (a_1) is 50 based on the weight of (A_1)
% or more of the binder according to claim 1. 3, (a_1) is polyhydric alcohol; cyclic dicarboxylic acid,
its anhydride or its dialkyl ester; and ε
3. A binder according to claim 1 or 2, which is a polyester polyol from -caprolactone or 1,6-oxycaproic acid or an ester thereof. 4. The binder according to any one of claims 1 to 3, wherein (A_3) is a compound selected from the group consisting of oxyacids, amino acids, and mercapto acids. 5. A high molecular weight polyol (A_1) with an equivalent weight of 200 to 2000, including a cyclic dicarboxylic acid-modified polycaprolactone polyol (a_1), a low molecular polyol (A_2), and a compound having a carboxyl group and other active hydrogen-containing groups in the molecule (A_3 ) of an active hydrogen-containing compound component (A) and an organic polyisocyanate (B) [provided that the molecular weight per carboxyl group in (C) is 1,000 to 50,000; be〕
1. A magnetic recording material comprising a binder for a magnetic recording material consisting of: and a magnetic material.