JPH03153785A - Method for producing polyurethane resin binder for magnetic recording media - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a binder for magnetic recording media, and more particularly, the present invention relates to a binder for a magnetic recording medium, and more particularly, the present invention relates to a binder for a magnetic recording medium formed on a non-magnetic support. The present invention relates to a binder for magnetic recording media that is made of Ingu and has excellent dispersion properties, electromagnetic conversion properties, etc.

[Conventional technology]

Generally, magnetic recording media used in audio equipment, video equipment, computers, etc. (specifically, audio equipment,
(used for video tapes, floppy disks, computer data tapes, etc.) is made by coating a magnetic paint containing magnetic powder and a binder on a non-magnetic support such as polyester film and drying it to form a magnetic layer. can get.

As a binder for forming the magnetic layer of such a magnetic recording medium, vinyl chloride resin, polyurethane resin, polyester resin, nitrocellulose resin, epoxy resin, etc. are generally used.

In recent years, with the expansion of uses for magnetic recording media such as audio tapes, video tapes, and computer data tapes,
Although the required performance is wide-ranging, the demand for high reliability of magnetic recording media is increasing in particular. Specifically, clear sound,
There is a particular demand for high-density recording for recording and reproducing oil.

As a measure to increase the density, 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 backing density. As the specific surface area increases due to the finer particles of magnetic powder and the cohesive force increases due to higher magnetic force, dispersion becomes difficult. Conventional binders cannot obtain titrable dispersibility and surface properties, and magnetic powder It has also become difficult to increase the backing density of

In recent years, it has been proposed to introduce a variety of hydrophilic polar groups to improve dispersibility. For example, So, M group,
A C00M group, a P=0 (OM') group, a 01 (group) and a tertiary amine group (M is hydrogen or an alkali metal, M' is hydrogen, an alkali gold 316 or a hydrocarbon group), etc. are considered. However, in the case of the former three polar groups, when these are introduced, the resulting resin becomes cloudy, and precipitation and separation occur over time.In addition, the viscosity of the magnetic paint in which magnetic powder is dispersed using these groups is This increases as the amount of polar groups introduced increases, making it difficult to manufacture magnetic recording media.

The latter two have low dispersion power, and even if the amount of polar groups introduced is increased, their performance is insufficient as a binder for finely divided magnetic powder or metal magnetic powder with a high amount of magnetization, so improvement was desired. .

[Problem to be solved by the invention]

In order to eliminate the above-mentioned defects, the present inventors have carried out extensive research and study, and have found that when a polyurethane resin into which a specific hydrophilic polar group is introduced is used as a binder, the dispersibility of magnetic powder and the surface of the magnetic layer can be improved. It was discovered that a magnetic recording medium with significantly improved properties could be obtained, and the present invention was achieved.

[Means to solve the problem]

That is, the present invention provides a polyurethane resin used as a binder for magnetic recording media having a number average molecular weight of 500 to 30.
00 polyol, a chain extender, a hydrophilic polar group-containing active hydrogen compound, and an organic diisocyanate, and the hydrophilic polar group-containing active hydrogen compound has the following general formulas (1) and (1). Using an active hydrogen compound containing a quaternary ammonium salt, 0.001 mmol/g of the quaternary ammonium salt was added to the polyurethane resin.
Containing ~1.0 mmol/g 1&: Featured polycrethane resin Pynodar-D-Z for magnetic recording media (wherein A and B are divalent organic chains having 10 or less carbon atoms, D member prime number 20 The following trivalent organic chain. 几1.几2゜R8 is an aliphatic group such as an alkyl group or an aryl group having 1 to 10 carbon atoms, or an aromatic group such as a phenyl group or a benzyl group. The anions, Y and Z represent active hydrogen groups that can react with isocyanate groups.

Regarding each component constituting the polyurethane resin of the present invention,
This will be explained below.

Examples of the polyols having a number average molecular weight of 500 to 3,000 used in the present invention include polyester polyols, polyester amide polyols, polyether posiols, polyether ester polyols, and polycarbonate polyols.

Polyester polyol, polyester amide polyol, polyether polyol, polyether polyol of the present invention
Specific examples of the ester polyol include known cono-phosphoric acid, adipic acid, sebacic acid, azerai/acid, terephthalic acid, isophthalic acid, hexahytrothyrentalic acid, hexahydroisophthalic tR, or acid esters thereof; Dicarboxylic acids, acid esters, acid anhydrides such as acid anhydrides, ethylene glycol, 1.3-7' Robylene glycol, 1.2-7' Robylene glycol, 1.4-
Butylene glycol, 1,5-penonane glycol, 1
．． 6-hexane glycol, 3-methyl-1,5-pentane glycol, neopentyl glycol, 1.8
- Glycols such as octane glycol, 1,9-nona/diol, diethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimetatool, or ethylene oxide or propylene oxide adducts of bisphenols, hexamethylene diamine, xylene Polyester polyols, polyesteramide polyols, or 6-caprolactone, alkyl-substituted C-cabrolactone 11 δ, obtained by dehydration condensation reaction with diamines such as diamines, inphorone diamines, and monoethanolamines, or aminoalfurs alone or with mixtures thereof. - Polyester polyols such as lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester (lactone) monomers such as valerolactone, alkyl-substituted monomers, and the like are examples of polyether polyols, such as polyethylene glycol and polypropylene. Examples include ether polyol and polytetramethylene ether polyol. Examples of polyether/ester polyols include polyester polyols produced from the above-mentioned polyether polyols and the above-mentioned dicarboxylic acids or acid anhydrides.

Polycarbonate posiols are generally obtained through the ethanol-free condensation reaction between polyhydric alcohols and diethyl carbonate, the phenol-free condensation reaction between polyhydric alcohols and diphenyl carbonate, or the ethylene glycol-free condensation reaction between polyhydric alcohols and ethylene carbonate. and this polyhydric alcohol is 1.6-
Hexane glycol, diethylene glycol, propylene glycol, 1.4-butylene glycol, 3-methyl-1,5-pentane glycol, 1.5-pentane glycol, neopentyl glycol, 1,8-octane glycol, 1.9- Aliphatic glycols such as nonane glycol, 1,10-deca/glycol, or 1.
Polycarbonate polyols consisting of alicyclic glycols such as 4-cyclohexane diglycol, 1,4-cyclohexa/dimetatool are used.

Chain extenders used in the present invention include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5
-pentane glycol, 1.6-san glycol,
3-Methyl-1,5-pentane glycol, neopentyl glycol, 1.8-octane glycol, 1.9-
Nonane glycol, diethylene glycol, fuclohexane-1,4-glycol, cyclohexane 7-1,4-
Glycols such as ethylene oxide or propylene oxide adducts of dimetatool or bisphenol, diamines or amino alcohols such as hexamethylene diamine, xylene diamine, inphorone diamine monoethanolamine, N,N'-dimethylethylene diamine, etc. Water and urea, which react with incyanate groups to form urea bonds, as shown in JP-A-61-107531, can also be used as chain extenders.

These above-mentioned compounds can be used alone or in the form of mixtures thereof.

As the active hydrogen compound containing a quaternary ammonium salt as the hydrophilic polar group-containing active hydrogen compound used in the present invention, compounds represented by the following general formulas (1) and (It) are used.

Y -D -Z (wherein A and B are a divalent organic chain having 10 or less carbon atoms, and D is a trivalent organic chain having 20 or less carbon atoms. R1t J +R,
is an aliphatic group such as an alkyl group or an aryl group having 1 to 10 carbon atoms, or an aromatic group such as a phenyl group or a benzyl group. X-
is an organic or inorganic anion, and Y and Z are active hydrogen groups capable of reacting with an isocyanate group, and may be the same or different OH group, NH group, NH group, SH group, COOH group, etc. ) As a specific example of general formula (1), for example, bis(2-
hydroxyethyl)dimethylammonium chloride,
Bis(2-7minoethyl)dimethylammonium chloride, bis(4-hydroxybutyl)dimethylammonium chloride, bis(4-carboxylbutyl)dimethylammonium chloride, bis(6-hydroxyhexyl)dimethylammonium chloride, bis(6-
aminohexyl)dimethylammonium chloride, bis(6-mercaptohexyl)dimethylammonium chloride, bis(8-hydroxyoctyl)dimethylammonium chloride, bis(2-hydroxypropyl)dimethylammonium chloride, 6-hydroxyhexyl-2-aminoethyl -dimethylammonium chloride, bis(6-hydroxyhexyl)diethylammonium chloride, bis(6-hydroxyhexyl)
Diphenylammonium chloride, bis(2-hydroxypropyl)methylphenylammonium chloride, bis(2-methyl-3-hydroxypropyl)dimethylammonium chloride, and these compounds,
Chloride is bromine, 5j! , valatoluene sulfonate, and the like.

Further, as a specific example of the pattern hole (1), for example, 2°3
-dihydroxypropyltrimethylammonium chloride, 2.3-diaminopropyltrimethylammonium chloride, 3.4-dihydroxybutyldimethylphenylammonium chloride, 3-hydroxy-4-
Aminobutyltrimethylammonitum cumylide, 4-
Jetanolaminophenyltrimethylammonium chloride and these compounds, where the chloride is bromine,
Compounds such as iodine, paratoluenesulfonate, etc., further K are 4-(3-hydroxy-2-hydroxymethyl)propyl-N, N-dimethylaniline, 4-(3-amino-2-aminomethyl)propyl-N .

Examples include alkyl halogen salts such as N-dimethylaniline, 4-(3-hydroxy-2-hydroxymethyl)propyl-N, and N-diethylaniline, and alkyl p-toluenesulfonic acid salts.

These compounds can be used as they are as part of the chain extender, but they can also be used as glycol raw materials for the above-mentioned polyols. For example, a ring-opening polymerization reaction using a cyclic lactone monomer such as ε-caprolactone, alkyl-substituted e-caprolactone, δ-valerolactone, or alkyl-substituted δ-valerolactone, or a dehydration condensation reaction with a known dicarboxylic acid, or the above-mentioned Through transesterification reactions with polyester polyols, polyester polyols can be produced, and by using these compounds as initiators during the production of polyether polyols, polyether polyols can be further produced as polyhydric alcohols, which are raw materials for polycarbonate polyols. Polycarbonate polyols can be obtained by using these compounds. The polyols obtained in this way can be used as active compounds containing quaternary ammonium salts.

The concentration of the quaternary ammonium salt used in the present invention is 0.001 mmol/g to 1.0 mmol/g.
, more preferably 0.005 mmol/g ~ 0
．． 5 mmol/g. Density is 0.001 mm
If the concentration is less than 1.0 mmol/fl, the dispersibility is insufficient for the finely divided magnetic particles, and the desired magnetic properties and electromagnetic conversion properties cannot be obtained.If the concentration is more than 1.0 mmol/g, the resin The paint becomes cloudy, precipitates are generated, and the viscosity of the magnetic paint made from the resin becomes high, making it difficult to coat it on a non-magnetic support.

The organic diisocyanate used in the present invention includes 2
．． 4-tolylene diisocyanate, 2.6-)lylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 4°4'-diphenylmethane diisocyanate (MDI), 4.4'
-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate), 2.2'-diphenylpropane-4,4'-diisocyanate, 3.
3'-dimethyldiphenylmethane-4,47-diisocyanate), 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3.
Aromatic diisocyanates such as 3'-dimethoxydiphenyAI-4,4'-diisocyanate, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, lylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane Diisocyanate, alicyclic diisocyanate such as cyclohexane diisocyanate, etc. can be mentioned. These organic diisocyanates may be aromatic, aliphatic, or alicyclic, and are selected depending on the desired physical properties of the resin.

Each component constituting the polyurethane resin of the present invention is a polyol having a number average molecular weight of 500 to 3,000, a chain extender, and a molar ratio FL of the total number of moles of an active hydrogen compound containing a quaternary ammonium salt to an organic diisocyanate. (Isocyanate group/hydroxyl group) t-0.80-1.05, preferably 0.85 to 1.00.

The binder obtained in this way is edge-shaped and has hydroxyl groups at both ends, and has a number average molecular weight of 10,000 to 130,000.
Preferably, it is a polyurethane resin having a molecular weight of 20,000 to 60,000. In this case, if the molecular weight is reduced by 10,000 p, it is advantageous because it has excellent dispersibility, but the am-forming ability of the resin becomes insufficient, resulting in poor durability and surface smoothness. become inferior. When the molecular weight is greater than 130,000, the dispersibility decreases and the viscosity increases, resulting in poor workability in the mixing, transporting, and coating processes in paint production.

The polyurethane resin of the present invention can be produced using known methods, such as bulk polymerization (solid reaction) in which the reaction is carried out in the molten state, ketone solvents such as methyl ethyl ketone (MgK), methyl isobutyl ketone (MIBK), and cyclohexanone, and acetic acid. Ester solvents such as ethyl and butyl acetate, ether solvents such as dioxane and tetrahydrofuran, glyfur ethers known as cellosolve and calpitol, acetic acid glycol ethers such as cellosolve acetate, amide solvents such as dimethylacetamide and dimethylformamide. , a solution polymerization method in which each of the above-mentioned components is dissolved and reacted in a single a or mixed solvent such as an aromatic hydrocarbon solvent such as toluene or xylene, or an alcohol solvent such as methanol, ethanol or ingropanol. etc. can be used. Further, a catalyst and a stabilizer can be used as necessary. Examples of catalysts include g11-containing compounds such as triethylamine and triethylenediamine, and dibutyltin dilauret (DB
Examples include organometallic compounds such as TDL), tin octylate, and zinc stearate.

As stabilizers used in the present invention, ultraviolet absorbers such as substituted benzotriazoles, antioxidants such as phenol derivatives, hydrolysis inhibitors, etc. can be added. In addition, if necessary, other polyurethane resins commonly used as binders for magnetic recording media, vinyl chloride h-vinyl acetate copolymers, polybutyl butyral resins, cellulose resins,
Polyester resin, polyurethane resin and phenoxy resin,
Thermosetting resins or reactive resins such as acrylonitrile-butadiene copolymers and unsaturated prepolymers, such as urethane acrylic types, polyester acrylic types,
Alternatively, as a polyfunctional monomer, a urethane acrylic type, a phosphorus ester acrylic type, an aryl type, etc. can be used in combination with an ultraviolet curable resin.

As the magnetic powder used in the present invention, for example, r-Fe
, Os, Co-containing r-Fe203, etc. iron oxide magnetic powder,
CrO□, hexagonal barium ferrite fine particles, and F
e, Ni, Co, re-Ni-Co alloy, Fe-Mn-
Examples include various ferromagnetic powders such as metal magnetic powders mainly composed of Fe, Ni, and Co such as Zn alloys.

In addition to being used for magnetic recording media, the polyurethane resin according to the present invention can also be used in paints, adhesives, sealants, waterproofing agents, flooring materials, artificial leather, textile processing agents, elastic fibers, cushioning materials, sheets, belts, films, and rolls. It can be used for gears, solid tires, vibration isolators, tubes, backing materials, shoe soles (microcellular), etc.

[For production]

In this way, 0.001 of the quaternary ammonium salt is added to the resin.
By using a polyurethane resin containing 1.0 mmol/g as a binder, the dispersibility for magnetic powder and the surface properties of the magnetic layer can be greatly improved. [Example] Next The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the same examples, "parts" and "chi" are "parts by weight" and "heavy weight parts" unless otherwise specified.

Example 1 Into a reaction vessel equipped with a thermometer, a stirrer, and a condenser, 1000 parts of polyhexamethylene inphthalate having a number average molecular weight (Mn) of 1000, a total of 18 parts of 1.4-butylene glycol, and bis(6- Add 0.1 part of hydroxyhexyl)dimethylammonium chloride (hereinafter abbreviated as HHMAC), 610 parts of cyclohexanone, and 0.05 part of DBTDL as a urethanization catalyst at 50°.
After mixing at 80° C., 329 parts of MDI (R=0.99) was added and reacted at 80° C. As the viscosity increases with time, dilute with cyclohexanone and MEK at appropriate times so that the weight ratio of MEK and cyclohexanone is 1:1.
The total amount of solvent was 4160 parts, and a transparent pale yellow liquid was obtained. This polyurethane resin solution has a solid content of 25.4% and a viscosity of 35%.
At 00cP/25°C, the number average molecular weight was 26,100.

Examples 2 to 8 A polyol, a chain extender,
Synthesis was carried out by changing the organic diisocyanate and the type of quaternary ammonium salt introduced.

The solvent used was changed in a timely manner. The composition and properties of the synthesized polyurethane resin solution are shown in Tables 1 and 2, respectively.

Example 9 Synthesis was carried out in the same manner as in Example 7 except that polyol and quaternary ammonium salt were transesterified at 170 to 180° C. for 4 hours.

The composition and properties of the polyurethane resin solution are shown in Tables 1 and 2.
Shown below.

Comparative Examples 1 to 3 Nine syntheses were carried out in the same manner as in Example 1.3.7, except that the quaternary ammonium salt was not used. The composition and properties of the polyurethane resin solution are shown in Tables 1 and 2.

<Evaluation of magnetic paint and magnetic layer> Application example 1 Using the polyurethane resin IW liquid obtained in Example 1,
Mix the composition with the following proportions in a tabletop sand grind mill (
Dispersion was carried out for 8 hours using Igarashi Kikai KK11), and the obtained magnetic paint was applied onto a 12 μm thick polyethylene terephthalate film to a thickness of 5 μm after drying, and dried.
I looked at the gloss level. The results are shown in Table 3. Coronate L was added as a polyisocyanate to the magnetic paint obtained by dispersing it for 98 hours.
(manufactured by Nippon Polyurethane Industries) as a hardening agent (solid content 75%)
Add 10 parts to 100 parts of the polyurethane resin solution obtained in Example 1 in terms of resin content,
After further mixing for 1 hour, it was coated on a polyethylene terephthalate film with a thickness of 12 μm to a thickness of 5 μm after drying while applying a magnetic field of 2000 Gauss.
A magnetic tape was obtained after being left at 60°C for one day.

Table 3 shows the results of the squareness ratio (Br/Bm).

Compound composition for magnetic recording media Cor-Fe103 100 parts Polyurethane resin (in terms of resin content) 25 parts Lectin
2 parts toluene 110 parts MEK
110 parts cyclohexanone
70 parts Application Examples 2 to 8, Comparative Examples 1 to 3 Instead of the polyurethane resin solution used in Application Example 1, the polyurethane resin solution obtained in Examples 2 to 8 and Ratio Examples 1 to 3 (Comparative Example-1) Application example 1 using ~(Comparative example-3)
The dispersibility and magnetic tape characteristics were evaluated using the same formulation. The results are shown in Table 3.

Glossiness: The reflectance at an incident angle of 60 degrees and a reflection angle of 60 degrees was observed using a glossy needle on the surface of the magnetic tape coated with #4.

Squareness ratio (Br/Bm): Saturation magnetization and residual magnetization were measured using VSM-3 type (manufactured by Toei Kogyo Co., Ltd.).

Note 8 to Table 2: PDM/PT8:4-(3-hydroxy-2-1, H
HMAC: bis(6-hydroxyhexyl)dimethylammonium chloride 2, HHEAI: bis(6-hydroxyhexyl)diethylammonium iodite 3, AEMAC: bis(2-aminoethyl)dimethylammonium chloride 4, HBMAB: bis(2-hydroxy) ethyl)dimethylammonium bromide 5, PDMAC: 4-(3-hydroxy-2
-hydroxymethyl)propyl-N,N-dimethylaniline methyl chloride salt 6, PDMAB: 4-(:l-amino-2-
Methyl bromide salt of hydroxymethyl)propyl-N,N-dimethylaniline 7, PDMAI: 4-(3-hydroxy-2-
Hydroxymethyl)propyl-N, Methyliodite of N-dimethylaniline Hydroxymethyl)propyl-N.

Methylvalatoluene sulfonate salt of N-dimethylaniline Table 3 [Effects of the invention] As is clear from the above explanation, the polyurethane resin of the present invention has a quaternary ammonium salt as a hydrophilic polar group in the resin. oot~1. By introducing Ommol/g, the dispersibility of the magnetic powder can be improved, and when this is used as a material for the magnetic layer, a high-density magnetic recording medium can be obtained.

Claims (1)

[Scope of Claims] A polyurethane resin used as a binder for magnetic recording media is prepared by reacting a polyol with a number average molecular weight of 500 to 3,000, a chain extender, a hydrophilic polar group-containing active hydrogen compound, and an organic diisocyanate, and the hydrophilic As a polar group-containing active hydrogen compound, the following general formula (I
), using an active hydrogen compound containing a quaternary ammonium salt having (II), add 0.001 mmol/g to 1.0 mmol of the quaternary ammonium salt in the polyurethane resin.
A polyurethane resin binder for magnetic recording media, characterized in that it contains /g. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, A and B are divalent organic chains with 10 or less carbon atoms, and D is a carbon number of 20. The following trivalent organic chains: R_1, R_2, R_
3 is an aliphatic group such as an alkyl group or an aryl group having 1 to 100 carbon atoms, or an aromatic group such as a phenyl group or a benzyl group. X
^- represents an organic or inorganic anion, and Y and Z represent active hydrogen groups capable of reacting with isocyanate groups. )