JPS6157041A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To reduce considerably the time required for curing and to improve productivity by forming a magnetic coated film layer on a substate and bringing a specific amine compd. into contact with the magnetic coated film layer in an optional state after said formation. CONSTITUTION:The tertiary amine compd. which has <=200 deg.C b.p. and does not contain active hydrogen is brought into contact with the magnetic coated film layer in an optional stage after the formation of the magnetic coated film layer on the substrate. The tertiary amine compd. contg. no active hydrogen refers to the tertiary amine compd. without contg. a hydroxyl group, amino group, carboxyl group, active methylene group, etc. which have high reactivity with an isocyanate group. The coated film is subjected to air blowing or a short period of heating treatment to evaporate the unnecessary tertiary amine when such kind of amine is used. The deterioration of the surface smoothness and durability is then obviated.

Description

[Detailed Description of the Invention] [Field of Application on Parallel] The present invention relates to a method of manufacturing a magnetic recording medium.
In detail, by employing specific processing means, magnetic coatings containing binders can be produced. The present invention relates to an economically advantageous method for manufacturing a magnetic recording medium that omits heat curing treatment of the Q layer.

[Prior art]

Conventionally, as one of the manufacturing methods of magnetic recording media.

After forming a magnetic coating layer by applying a magnetic paint containing a binder containing a polyisocyanate compound and an active hydrogen-containing resin to a magnetic powder on a support, an orientation treatment is performed as necessary. , Yaf.

A manufacturing method is known in which surface treatment and heat curing treatment are then performed.

This manufacturing method uses a binder that undergoes a crosslinking reaction when heated and hardened, so it is possible to produce magnetic recording media with high coating film strength and excellent abrasion resistance and moist heat resistance. The curing process requires a long time, which results in low production efficiency, and also has disadvantages in that the manufacturing equipment becomes large due to the process.

In other words, in the production method described above, the curing of the binder progresses through the steps of orientation treatment and surface treatment, but this alone is not sufficient;
It is necessary to perform heat curing treatment at o-, ro°C for 2ILt hours.

[Purpose of the invention]

An object of the present invention is to provide an economically advantageous method for manufacturing a magnetic recording medium that eliminates the heat curing process that requires a long time.

17 Therefore, the object of the present invention is to prepare a polyisocyanate compound and an active hydrogen-containing compound (#J1) on a support.
Magnetic paint containing llr k-containing 1r binder and magnetic powder is applied [7 (Q ?l rA IIIJ +1
Form 4, 1/r, t/+, etc., apply l'r as necessary to perform orientation treatment, and then perform unikawa treatment to produce a magnetic recording medium. To present 1, child Q 17)
IQ I'K f, la 4'L @ lbJ ,'
r'j K f) lj Point i) I -2001: I:
This is achieved by contacting the tertiary amine compound di1, which is J, '1 and does not contain active hydrogen.

[Structure of the invention]

Supports include polyethylene phthalate, polyamide,
Polyolefin, cellulose Kll iH material, and non-magnetic metal paper are used, and the shapes are films, tapes, sheets, cards, disks, etc.

The polyisocyanate compound used in the present invention includes an adduct having one or more iso7anate groups (
an adduct of diincyanate and a covalent or trivalent polyhedral alcohol, an adduct of diisonoanate and water,
diincyanate dimer, 31-dimer, etc.) can be used.

As such a polyisocyanate compound, Bayerio (product name: Tennis Module L1 Nippon Polyurethane Kogyo QI F
! Coronate L1 Mitsubishi Chemical Qsu's Mytic a
prorh (registered trademark), He-Samethi [/ Part name of Tennis module N1 made by Bayer AG made from inholone diisocyanate and Mitic NY made by Mitsubishi Rhine Industries Co., Ltd. made from inphorone diisocyanate as a raw material. ,! /FA
and so on.

Among these, aromatic diisocyanates are used as raw materials, Tennis Module L1 Coronate I,...? ITETSUKU GPL
OjA is particularly preferred.

These polyisocyanate compounds are used in proportions of 3 to 1% SO (by weight) of the total binder.

The active hydrogen-containing resins used in the present invention include hydroxyl group-containing polyurethane resins, water rR group-containing epoxy resins, polyester resins, acrylic resins, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and vinyl chloride containing vinyl alcohol components. - Vinegar R Rental Vinyl Synthesis R Combined, 1F Vinyl A-H1 Acid Hynyl Malein #t J'G Hi Combine 1+' * 2) rx Cell [1-S etc. are single! do.

These active hydrogen-containing resins contain io to
It is used at a rate of 1-1.

It is also possible to use cyclized vinyl-vinegar rf vinyl copolymers, acrylic resins, which do not contain active hydrogen, as part 7 of the binder.

The magnetic powder 1 used in the magnetic paint for magnetic recording media of the present invention is selected from commonly used powders, such as γ-
Iron oxide, cobalt-coated γ- iron oxide, cobalt-doped γ-
Examples include iron oxide, chromium dioxide, alloy magnetic powder, metal magnetic powder, and the like.

It is selected from the range of Aj to io7 (weight ratio).

Furthermore, when forming the magnetic layer of a magnetic recording medium, various commonly used additives may be used as required.

It is known as a solvent that has been used for a long time except for the production of magnetic paint)
Ketones such as nonalenalketone, methyl isobutyl ketone and nclohexanone, esters such as ethyl acetate and hkn-phthyl acetate, and aromatic hydrocarbons such as toluene and quinolene are used.

In the method of the present invention, first, a magnetic powder and an active hydrogen 6-containing resin are mixed and dispersed in the presence of h-shavings, and then subjected to a d-1 filtration, and then a polyisocyanate compound is mixed to prepare a lubricant paint. This is coated onto a support to form a magnetic coating layer. The magnetic powder is dispersed using a sand grinder, ball mill, etc.

Magnetic coating film; - is subjected to orientation treatment as necessary.

Mosquito orientation treatment is carried out by passing a magnetic coating through a static magnet.

Next, the magnetic coating layer is subjected to a surface treatment such as calender treatment or vernishoche treatment, but in the method of the present invention, at any stage after the formation of the magnetic coating layer, a special treatment is applied to the magnetic coating layer. The biggest feature is that it comes into contact with Hiroshi's amine compound.

Since there is a lot of magnetic powder in the bent surface and the surface is porous, the impregnation properties of tertiary amine compounds are particularly good.
Curing is completed in the order of 0 seconds, and curing can be significantly accelerated.

However, magnetic recording media have high electromagnetic conversion characteristics and
Since durability such as abrasion resistance is required, the optical surface smoothness and durability of the coating film are required compared to general coating films. Therefore, these performances deteriorate.

Moreover, 9 speed (it is necessary to select one tertiary amine to be cured).

The tertiary amine that can be used in the present invention is QJ trimethylamine.

Examples include ethyldimethylamine/tetramenalethylamine, tripropylamine, N-,N-dimethylamine/chlorohexylamine, and N-methylmorpholine.

A tertiary amine compound that does not contain active hydrogen refers to a tertiary amine compound that does not contain a hydroxyl amine group, carboxyl group, or active methylene group that is highly reactive with isocyanate groups. As a tertiary amine containing active hydrogen,
) l-,14'-dimethylethanolamine N-methyljetanolamine, etc., but when used, it reacts with the incyanate group, impairing the optical surface smoothness of the magnetic recording medium, and causing tertiary compounds in the coating film. Nitrogen content is not preferred because durability may be reduced. Also boiling point 20
It is also not preferable to use a tertiary amine having a temperature of 0° C. or higher because it tends to remain in the coating film.

Therefore, it is necessary to use a tertiary amine compound that does not contain active hydrogen and has a boiling point of 200°C or less. When using this type of amine, air blowing or short heat treatment is performed after the coating film is cured, eliminating unnecessary By volatilizing the tertiary amine, the surface smoothness is not impaired or the durability is reduced as described above.

A method for accelerating the hardening of a magnetic coating without shortening its working life is to apply a catalyst 1 used in the urethanization reaction to the magnetic coating, such as a tin ll medium such as dibutyltin dilaurate, dioctyltin dilaurate, or stannous octoate. It is also possible to apply a tertiary amine catalyst such as triethylenediamine directly or dissolve it in a solvent, but in this case, since the above catalyst has a high boiling point, it may remain on the surface of the magnetic coating film. In particular, the surface smoothness deteriorates and the electromagnetic conversion characteristics of the magnetic recording medium are deteriorated.
The durability of the magnetic recording medium may deteriorate.

There are two methods for bringing the tertiary amine compound into contact with the magnetic coating layer: one method is to bring the tertiary amine compound into contact with the tertiary amine compound in a vapor state, and the other method is to bring the tertiary amine compound into contact in a molten state. It is preferable to make contact at An example of a method of melting in a vapor state is to create a curing chamber with a tertiary amine compound atmosphere in which the tertiary amine compound is atomized and circulated using compressed air, and a magnetic coating film is placed in the curing chamber. There is a way to enter it.

Examples of methods for contacting in a liquid state include a tertiary amine compound alone that is liquid at room temperature, or a tertiary amine compound diluted appropriately with a known low-boiling solvent that does not easily dissolve the magnetic coating, such as n-hexane. There is a method in which a solution of a class amine compound is prepared and the solution is applied by a conventional method or the magnetic coating is placed in a bathtub and the magnetic coating is immersed for a certain period of time.

The degree of the tertiary amine compound in these vapors and solutions is related to the curing rate, etc., but from lθ0PPro to 100
It can be used in the range of %.

The step of instantly curing the coating film by bringing it into contact with the tertiary amine compound of the present invention is carried out after applying the magnetic coating.

Calendering can be carried out at any stage, but in order to obtain a coating film with higher surface gloss and smoothness, calendering is recommended! It is preferable to carry out this after the front surface smoothing treatment step.

Examples of surface gloss and smoothing treatment methods include calender treatment and parnish treatment j1. After curing the coating film with a tertiary amine compound, it is preferable to remove the tertiary amine by air blowing or heating for a short time.

In other words, the tertiary amine is Ek it! If PC remains on the surface, the surface smoothness deteriorates, the electromagnetic conversion characteristics of the magnetic recording medium deteriorate, and the durability of the magnetic recording medium deteriorates.

〔Example〕

Next, the present invention will be specifically explained in terms of a furnace using Examples, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded.

In the examples, "1 part" represents a heavy twill part.

Magnetic paint production example/Polyurethane resin 3173 parts (Japan Polyurethane H3EN-r Joa) Nitrocellulose 110 parts (Asahi Kasei Kohata 0)
FM-Cooo) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer j
Q part (Kikagaku Kogyo q10jf to θθGKT) -
] l-1/nchin io part ts carbon black group. Department CoJ Yur-Fe,
o3 741° parts methyl ethyl lactone Octopus. cannon to part cyclo
310 parts methyl isobutyl ketone J10
8 After mixing and dispersing the above mixture in a sand grind mill for 2 hours, P-passing was carried out, and then a polyisocyanate compound such as Mytic Aprorh (registered trademark of Mitsubishi Chemical Industries, Ltd.; Nitrilene diisocyanate (TD) manufactured by Mitsubishi Chemical Industries, Ltd.) Methylolpropane reactant) 3! The components were mixed to obtain a magnetic paint.

Magnetic paint production example Copolyurethane resin 34 parts 3 parts (N-53oa manufactured by Nippon Polyurethane) Nitrocellulose
iso section (manufactured by Asahi Kasei Corporation FM-s)
oo) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 6
0 parts (manufactured by Denki Kagaku Kogyo EA, 1oooaKT) lecithin io part carbon black <to part CO-containing T-FelOl
7uO part methyl ethyl ketone
2.20 parts cyclohexanone 3
10 parts Methyl inbutyl ketone 310 parts The above mixture was mixed and dispersed in a sand glide mill for t hours, and then subjected to P-distillation to obtain a polyincyanate compound using Mytic tJYu/J'A (Mitsubishi Chemical Corporation ■ registered trademark; Mitsubishi Chemical Industrial ■: Isophorone diisocyaner)
(A reaction product of IPDI and triol) was mixed to obtain a magnetic paint.

Example 1 Magnetic paint production example - The film thickness after drying the magnetic paint obtained in / on a polyethylene terephthalate film! After coating it so that it becomes μ and drying it for 75 seconds at to℃, the triethylamine concentration is ! A film coated with a magnetic coating is placed in a room-temperature curing room with an atmosphere of −! Put it in for a second and check the degree of change in the coating using an ethyl acetate rubbing test and a Fourier transform infrared absorption spectrometer! (FT-Engineering R), Koza 30
The absorbance of the methylene group in cm' was set to 4. 2.2jO
The determination was made based on the degree of decrease in the absorbance of isocyanate groups in cm. The results are shown in Table 1.

Table 1 shows the surface gloss and surface roughness of the magnetic coating film subjected to calender treatment.

The magnetic paint transferred in Example 1 (Example 1 of manufacturing electrolytic paint) was dried on a polyethylene terephthalate film.
After drying at to°C for 70 seconds, the film coated with the magnetic coating was immersed in the triethylamine solution for 5 seconds to harden. Then, air blowing was performed for 30 seconds.

! ! The degree of hardening of the pus was determined by ethyl acetate rubbing test and FT-IR spectroscopy). Show results/
Shown below.

Table 1 shows the surface gloss and surface roughness of the magnetic coating film subjected to calender treatment.

Example 3 Magnetic paint production example! The magnetic @ phase obtained in Example 1 was made ξ (as in Example 1) and dried with a cloth. The film coated with the magnetic coating was immersed in the triethylamine solution for 0 seconds to cure it. Then, it was immersed in air for 30 seconds I did a blow job.

The degree of hardening of the coating film is shown in Table 1, and the surface gloss and surface roughness of the magnetic coating film are shown in Table 1.

Comparative Example 1 The magnetic paint prepared in Example 1 of Magnetic '11i Material Production was applied to a polyethylene terephthalate film so that the thickness of the film after drying was jμ, and was cured and dried at 10°C for 73 minutes.

Magnetic coating 1 calendered to show the degree of hardening of the coating film
The coating exhibits a vague surface gloss and roughness.

The contact treatment with the tertiary amine at 1/C and 1/2 required a curing time of t hours with a sufficiently cured coating (!-4gO).

Comparison N-2 The magnetic paint obtained in Magnetic Paint Production Example 1 was applied onto a polyethylene terephthalate film so that the film thickness of Nfif& was jμ, and then immersed in a dimethylethanolamine solution containing active hydrogen for 5 seconds. hardened. Then 3
Air blowing was performed for 0 seconds.

The degree of hardening of the coating film is shown in Table 1, and the surface roughness of the magnetic coating film is shown in Table 2.

Comparative Example 3 A magnetic coating film was obtained in the same manner as Comparative Example J, except that tributylamine having a boiling point of λl°C was used instead of the dimethylethanolamine liquid.

The results are shown in Table/.

Table/+l) Ethyl acetate rubbing method Judgment was made by rubbing the cured coating film with gauze impregnated with ethyl acetate solvent.

○: No change, Δ: Partially peeled off, ×: Mostly peeled off 2) Before curing by T-IR method (ANOO/AOH,) A) CO: Absorbance of isocyanate group (,2,2
jOO1,) AOH! : ) Absorbance of 7 groups
(IrjoC11-1) Kaoru 3) Gloss value: Measured using a digital variable angle gloss meter (manufactured by Suga Test Instruments) at an angle of incidence of 7 and an angle of acceptance of Fj'.

■-V) Surface roughness Ra): Measured by a two-dimensional No. 11 roughness measuring device (Sokoita Research Institute ψwas): Center line average roughness [Effects of the invention] The odor of the present invention is Linear J magnetic +1: By bringing a tertiary amine compound in a liquid or vapor state into contact with the coating layer, the isocyanate groups and hydroxyl groups in the magnetic coating layer and or The strength of the coating film is improved by rapid crosslinking reaction with active hydrogen such as carboxyl groups.

Therefore, the time required for curing is significantly shortened and productivity is improved.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - (7 others)

Claims (4)

[Claims] (1) After coating a binder containing a polyisocyanate compound and an active hydrogen-containing resin and a magnetic material containing magnetic powder on a support to form a magnetic coating layer, an orientation treatment is performed as necessary, and then When producing a magnetic recording medium by performing surface treatment, at any stage, a third layer having a boiling point of 200°C or less and containing no active hydrogen is added to the magnetic coating layer.
1. A method for producing a magnetic recording medium, which comprises contacting a magnetic recording medium with a class amine compound. (2) The method for manufacturing a magnetic recording medium according to claim 1, wherein the contact treatment between the magnetic coating layer and the tertiary amine compound is performed after the surface smoothing treatment. (3) A patent claim characterized in that the contact treatment between the magnetic coating layer and the tertiary amine compound is a contact treatment in which tertiary amine remaining on the surface of the magnetic coating layer is removed after the treatment. A method for manufacturing a magnetic recording medium according to scope 1 or 2. (4) A method for manufacturing a magnetic recording medium according to claim 1, 2, or 3, characterized in that the tertiary amine is used as vapor.