JPS62177722A - Binder and magnetic recording material - Google Patents

Abstract

PURPOSE:To improve the dispersibility of a magnetic material and calenderability by using a polyurethane composed of a specific polyol and org. polyisocyanate for a binder. CONSTITUTION:The polyurethane composed of the polyol (A) consisting of a high molecular polyol (A1) contg. a polyvalerolactone polyol (a) and low- molecular polyol (A2) and the org. polyisocyanate (B) is used. For example, polyvalerolactone diol or the like is preferable as the component (a) and the other high molecular polyol may be incorporated into the component A1 together with the component (a). The equiv. of the component A1 is made 200-2,000. The dispersibility of the magnetic material is low if the equiv. is out of said range. The dispersibility of the magnetic material is improved and the calenderability is improved according to the above-mentioned constitution, by which the workability is improved.

Description

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

[Conventional technology]

Conventionally, binders for magnetic recording materials have been made of polyurethane resins made of polycaprolactone polyol, trifunctional or higher-functional low-molecular polyol, and organic polyisocyanate (JP-A-57-60529 and JP-A-57-61). No. 530 Beho).

[Problem that the invention seeks to solve]

The calendering properties of L-type calenders were insufficient, and therefore the calender temperature could not be increased or the calender speed could be slowed down, resulting in insufficient workability.

[Means for solving problems]

The present inventors have conducted extensive studies to obtain a binder for a magnetic recording material and a magnetic recording material that have excellent ecalendering properties and excellent dispersibility of magnetic materials, and have thus arrived at the present invention.

That is, the present invention provides polyvalerolactone polyol (a1
) and a polyurethane resin (C) made of an organic polyisocyanate CB). Binder for materials (first invention), polyvalerolactone polyol (A1) and low molecular polyol (
A magnetic recording material (Second 2 invention).

Polyvalerolactone polyol (a1) in the present invention
As an initiator [glycol (ethylene glycol, etc.), triol, etc.]'x base, this (substituted) valerolactone (f-valerolactone, β-methyl-za-valerolactone, etc.) is used as a catalyst (organometallic Compounds, metal chelate compounds (1), fatty acid metal acylated compounds, etc.) can be added and polymerized to form polyols.

Among these, preferred is polyvalerolactone diol.

The equivalent weight of polyvalerolactone polyol is usually 200-2
o oo Preferably 400-15f [.

In addition to (a.), other polymeric polyols may be used in combination. This polymer polyol includes polycaprolactone polyol described in JP-A-57-613529.

Mako, polyether polyol [low molecular glycol (
Ethylene glycol, propylene glycol, 1.4-
Phthanediol, etc.; low molecular triols (glycerin,
trimethylone propane, hexanetriol, etc.);
Low-molecular-weight polyols with tetrafunctional or higher functionality (sorbitol, sucrose, etc.) or amines (alkanolamines,
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 the above-mentioned alkylene oxides). Specific examples include polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol.

In addition, polyester polyols (polycarboxylic acids (aliphatic polycarboxylic acids, such as adipic acid, maleic acid, and trimerized linoleic acid; aromatic polycarboxylic acids, such as phthalic acid) and low-molecular-weight polyols or polyether polyols) Droxyl group-containing polyester polyols], polymer polyols and polybutadiene polyols can also be used. Among these, polyester polyols are preferred.

The total content of polyvalerolactone polyol (a- and polycaprolactone polyol) in the polymer polyol (n) is usually 50% by weight or more, preferably 90-100% by weight, particularly preferably 100% by weight. Content When the amount is less than 50 ffi, the dispersibility of the magnetic material decreases.

The weight ratio of polyvalerolactone to polycaprolactone is usually 10:0 to 1:9, preferably 9:1 to 2:8.
The equivalent weight of the polymer polyol (A1) containing (a1) is preferably 8:2 to 5:5.
0 to 2500, preferably 400 to 150 I).

If the equivalent weight is less than 200, the dispersibility of the magnetic material in the resulting urethane resin will be lowered, and the scratch resistance will also be lowered. If the equivalent weight exceeds 2,500, the resulting polyurethane resin will have poor dispersibility in magnetic materials, abrasion resistance, scratch resistance, hydrolysis resistance, etc.

The low-molecular polyol (n) in the present invention is a low-molecular polyol (I).
They include alkylene oxide low molar adducts of Icols (ethylene glycol, propylene glycol, 14-butanediol, bisphenol A, etc.), low molecular weight glycols, or bisphenols (diphenol, bisphenol A, etc.).

Also included are trifunctional or higher-functional, low-molecular-weight polyols described in JP-A No. 57-60529.

Furthermore, the glycol ester of monohydroxy monocarboxylic acid described in Japanese Patent Application No. 1-17171 can also be used. When this is used, a large amount of polycaprolactone polyol may be used.

The equivalent weight of the low molecular weight polyol (N) is usually 30 to less than 200, preferably 45 to 150.

In the polyol (A), the low molecular weight polyol (N) is 20~
It is 95 equivalent %, preferably 30 to 80 equivalent %. If (n) is less than 20 equivalent %, the film properties of the produced urethane resin tend to deteriorate, and the magnetic t! The dispersibility of L powder is also poor. On the other hand, if the A content exceeds 95%, the dispersibility of the magnetic material in the produced urethane resin decreases.

High molecular polyol (A1) and low molecular polyol (A2)
The total equivalent weight of polyol (A) consisting of is usually 100 to
It is 1750. If the equivalent of (A) 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 1750, the dispersibility of the magnetic material of the produced urethane resin will decrease, and the strength of one film will be insufficient.
Abrasion resistance, scratch resistance, hydrolysis resistance, etc. decrease.

In the present invention G, the organic polyisocyanate (B) is an aromatic polyisocyanate, for example, an aromatic polyisocyanate, [tolylene diisocyanate (TD
I); 4.4'-diphenylmethane diisocyanate (MDI); modified MDI; 15-naphthylene diisocyanate; 44I-diisocyanate], aromatic polyisocyanate multimers (dimers and trimers such as TDI, MDI, etc.) and NCO-terminated urethane prepolymers of polyol and aromatic polyisocyanate [low-molecular polyol and an excess of aromatic polyisocyanate, such as trimethylo-/lephroban (1 mol) I
= TDI (3 mo/di) reactant] ; Non-aromatic polyisocyanates such as aliphatic diisocyanate (tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc.) and Alicyclic diisocyanates [hydrogenated TDI (hydrogenated tolylene diisocyanate), hydrogenated MDI (hydrogenated 44'-
diphenylmethane diisocyanate), isopropylidene bis(4-cyclohexyl isocyanate-1), isophorone diisocyate (IPDI) and bis(
(2-isocyanate ethyl) fumarate, etc.]; less than NC0 urethane prepolymer of trimer of non-aromatic polyisocyanate and polyol and non-aromatic polyisocyanate (polyol such as low-molecular polyol and excess non-aromatic polyisocyanate); (reactants of aromatic polyisocyanate).

Two or more kinds of the above organic polyisocyanes 1. can be used in combination.

Among organic polyisocyanates, preferred aromatic polyisocyanates include aromatic diisocyanates.
The non-aromatic polyisocyanates include aliphatic diisocyanate, especially hexamethylene diisocyanate, and JJi cyclic diisocyanate, especially IPDI. Particularly preferred is MDI.

In a polyurethane resin made from a polyol (A) and an organic polyisocyanate (B), the NC010I-1
The equivalent ratio is usually 0.6 to 1.5, preferably 09 to 1.2.
It is. NC010f-I equivalent ratio is less than 06 and 1.
If it exceeds 5, the molecular weight of the polyurethane resin obtained by the reaction with (A) and CB) will be the same, resulting in a decrease in dispersibility, and the scratch resistance, abrasion resistance, hydrolysis resistance, etc. of the magnetic recording material will decrease. Easy to do.

Polyurethane resin (C) can be produced by reacting (A) and (B) in the presence or absence of a solvent inert to incyanate groups. Solvents (ethyl acetate, butyl acetate, etc.), ether solvents (dioxanetetrahydrofuran, etc.), ketone solvents (cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aromatic hydrocarbon solvents (toluene, xylene, etc.), and mixed solvents thereof can be given.

The reaction methods include a method in which polyol (A) and aromatic polysonite (B3) are charged together in a reaction vessel and reacted, a method in which (A) and CB) are divided and reacted in a multistage manner, and Araka, 1 piece of Shime mixture (A) and (
B) can be passed through a heated continuous kneader to react.

The reaction temperature is usually 40 to 130°C, preferably 60 to 80°C. In order to accelerate the reaction, catalysts used in normal urethane reactions, such as tin-based catalysts (trimethyltin laurate, trimethyltin hydroxide, dimethyltin dilaurate, stannath octoate, etc.), lead-based catalysts (red oleate,
Red 2-ethylhexoate, etc.) can also be used.

The polyurethane resin (C) in the present invention has a number average molecular weight of usually 10,000 to 200,000, preferably 50,000 to 100,000, and Or-
The monovalent value is usually 15 or less, preferably 10 or less, and the NCO content is usually 8% or less.

Polyol (A1) and aromatic polyisocyanate (B
) Polyurethane (C) is used as a binder for magnetic recording materials, but due to the required Q, it is usually used for magnetic recording materials (IL+) polymeric materials can be used in combination.

Examples of this polymeric material include polyvinyl chloride (vinyl chloride-vinyl acetate copolymer (VYI-IH1UCC; manufactured by Eslec C1, Sekisui Chemical Co., Ltd.), vinyl chloride-vinyl acetate-vinyl alcohol copolymer (VAGI-1; Eslec C1, etc.); A), vinyl chloride-vinylidene chloride-acrylonitrile (Saran, manufactured by Asahi Dow), etc.], polyurethane-based [
Urethane resin (manufactured by Nisten, Guttrich, etc.), butadiene type [acrylonitrile-butadiene copolymer (Hiker 1432, manufactured by Nippon Zeon, etc.), acrylonitrile-butanediene-styrene copolymer (ABS), etc.]
, acrylic (such as various acrylic acid ester polymers), 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 also referred to as magnetic paint) by containing it and a magnetic substance. The magnetic substances include Fe (pure iron), r-Pesos (r -hematite), Cr0-
(chromium trioxide) and alloy-based magnetic materials such as Cu
-r Fetas (cobalt ferrite or cobalt-doped r-iron oxide) and Fe-Co C+ are prepared.

The magnetic material is magnetic powder, and its shape is generally granular or acicular. An example of the size (μ) of the magnetic material is the major axis 02 to 1. (1. Minor axis is 0.02 to 0.1.

Crosslinking agents that can be used to crosslink the polyurethane resin in the magnetic paint Q include NCO-containing compounds and active hydrogen-containing compounds. N.C.
As the O-containing compound, polyisocyanate [modified MD
I (Mirioi-to ME, manufactured by Hodogaya Chemical), 3.3'
-dimethoxy-44'-diisocyanate, etc.] and NCO-terminated prepolymers [polyisocyanate, -) (T
Dl, MDI, etc.) and polyols (low molecular polyols,
NCO-terminated prepolymers such as polyether polyols and polyester polyols such as Desmodur L (manufactured by Bayer), Coro 4. Active hydrogen-containing compounds include polyamines [tolylene diamine (TDA),
4.4'-Diaminediphenylmethane (MDA), 4.
(4'-diamino-33'-dichlorodiphenylmethane, etc.) and polyols (low molecular polyols, polyether polyols, polyester polyols, etc.).

The amount of crosslinking agent added is the same as that of polyurethane resin (71' L 1
lll usually O to 25% by weight, preferably f, X 2-1
It is 5% by weight. If the weight exceeds 25% and 1%), the flexibility of the ilm tends to decrease.

Other dispersants (lecithin, anionic, nonionic, cationic surfactants such as dodecylbenzenesulfonic acid sorter) and lubricants (higher fatty acid esters, such as butyl stearate) can also be added if necessary.

For magnetic paints, a solvent is used to adjust the viscosity. This solvent is described in the polyurethane resin production reaction section, and is similar to 1. 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, xylene, etc.), and mixed solvents thereof can be used. Among these, preferred are mixed solvents of ketones and aromatic hydrocarbons.

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

The amount of magnetic material in the magnetic paint is usually 30 to 80% by weight.

A method for producing magnetic paint is to mix the binder, solvent, and magnetic material in advance using a blender or the like if necessary, then disperse the mixture using a mixing/dispersing machine (ball mill, etc.), and then filter the magnetic paint. can be applied to support films 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 applying magnetic paint to a support film, the coating thickness ζ
The back side is usually several microns to several tens of microns. Application methods include coating methods such as the doctor blade method and the transfer stamp method (gravure method, reverse roll method, etc.).

The film coated with magnetic paint is then oriented, for example.
It is made into a magnetic recording medium through processes such as drying, calendering, cutting, and winding.

Calendering conditions are, for example, in the case of a paper coating agent, the temperature is usually 70-120°C, preferably 80-120°C.
The temperature is 90℃. The pressure is usually between 100 and 400! iJ/e
J, preferably 150 to 250 to 9/d.
The calendering speed is usually 10 to 60 m/min, preferably 20 to 60 m/min for paper coatings.

Magnetic recording media generally consist of a support film and a magnetic # (magnetic binder), but those with an intermediate layer (undercoat layer) between the support film and the magnetic layer, There are also cards with magnetic layers on both sides of the card, cards with stacked magnetic layers with different magnetic properties, and cards with a protective layer on the magnetic layer (protective cards).

〔Example〕

The present invention will be further explained below with reference to Examples, but the invention is not limited thereto. Parts in Examples indicate parts by weight.

Example 1 1 mole of polyvalerolactone diol with an equivalent weight of 425 and 1. A mixture of 4 moles of 4-furandiol and 5 TDI
A polyurethane resin (OHV 10) having only Q hydroxyl group terminals was obtained by reacting 1 mole of the resin. This is referred to as polyurethane tree JItT (C:1).

Using this (C1) as a binder, a mixture having the following composition was roughened, mixed in a flex mixer, and mixed and dispersed in a ball mill to prepare a magnetic paint (DI).

T VerOs fine powder 100 parts Polyurethane resin (C+1 20 parts (88
:12) Copolymer Desmodur L 2 parts lecithin
1 part methyl ethyl ketone
75 parts toluene 75
This magnetic paint was applied onto a polyester film so that the coating thickness after drying was 5 μm, and then dried.

This is pressed using a press at a linear pressure of 200 KS' and 3 per minute.
Calendar the film by passing it 1 to 3 times at a speed of 0 m. Also, the lA+S degree at this time is 8()°C. After calender treatment, tape width 12.65M
I cut it into G pieces. This is called a magnetic tape (E,).

Example 2 2 moles of polyvalerolactone diol with equivalent weight too, 1 mole of polytetramethylene glycol with equivalent (il 500)
A mixture of mol and 7 mol of 1,4-fucundiol and T
10 moles of DI were reacted to obtain a polyurethane resin JJi (OHV 8 ) having a hydroxyl group at the end, and this was designated as a polyurethane resin (C).

Composition of Example 1) Here, polyurethane tree JIFf (
2 parts of polyurethane resin (C6) in place of 320 parts of C+
Magnetic paint () was prepared in the same manner as in Example 1 except that 0 part was used.
) A magnetic tape was prepared by obtaining 1). Put this on magnetic tape (
E1).

Example 3 A polyurethane resin having only two terminal NCO groups (NCO content 5%) to polyurethane resin (C8)
shall be.

In the composition of Example 1, polyurethane resin (C, 12
A magnetic paint (Ds3) was obtained in the same manner as in Example 1 except that 20 parts of polyurethane resin (C5) was used instead. A magnetic tape was prepared, and this was designated as a magnetic tape (E).

Ratio 1 Bite 1 1 mol of polycaprolactone diol with equivalent weight 425, I4
- A polyurethane resin with a slight hydroxyl group end (OtlV
9) as qxh1, and this polyurethane resin is taken as a comparative example (C+').

Taking the composition of Example 1, polyurethane resin (C,)
A magnetic paint CD was prepared in the same manner as in Example 1 except that 20 parts of polyurethane resin (C,') was used instead of 20 parts.
') and created a magnetic tape. Put this on magnetic tape (
E,').

Test Example 1 The surface condition of the coating film of the magnetic tapes obtained in Examples 1 to 3 and Comparative Example 1 was observed using a microscope. Visually observe the degree of smoothness and check calendering properties.

The results are shown in Table 1.1 The smoother the surface, the better the calenderability.

Table 1 (Note) 0: Smooth surface.

△D Part of the surface is raised.

×: There are many protrusions.

Further, the dispersibility was also good for the magnetic tapes of Examples 1 to 3.6 [Effects of the Invention] The binder for magnetic recording materials and the magnetic recording material of the present invention were prepared using a conventional binder (Japanese Unexamined Patent Application Publication No. 57-57-1529).
No. 5, Japanese Patent Publication No. 530 (61), No. 530) and 530, the current characteristics are poor compared to the above. Therefore, it is not necessary to raise the temperature of the calender or slow down the calender speed, and this one-time workability is good.

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

Because the binder and materials of the present invention exhibit the above effects, they can be used, for example, in audio tapes, video tapes, computer tapes, data recorder tapes, video sheets, etc.
It is useful as a binder for magnetic recording materials and magnetic recording materials for metal disks and magnetic cards.

Claims (1)

[Scope of Claims] 1. A polyol (A_1) containing a polyvalerolactone polyol (a_1) with an equivalent weight of 200 to 2000 and a low molecular polyol (A_2);
) and an organic polyisocyanate (B). 2. The binder according to claim 1, wherein (A_2) in (A) is 20 to 95 equivalent %. 3. The binder according to claim 1 or 2, wherein the equivalent weight of (a_1) is 200 to 2,500. 4. The total equivalent of (A_1) and (A_2) is 100 to 1
750, the binder according to any one of claims 1 to 3. 5. The NCO/OH equivalent ratio of (A) and (B) is 0.6 to 1
．． 5. The binder according to any one of claims 1 to 4. 6. Polyol (A) consisting of a high molecular polyol (A_1) with an equivalent weight of 200 to 2000 and a low molecular polyol (A_2) containing polyvalerolactone polyol (a_1)
) and an organic polyisocyanate (B), a binder for a magnetic recording material consisting of a polyurethane resin (C) and an organic polyisocyanate (B), and a magnetic material.