JPS6057526A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having an excellent electromagnetic converting characteristic, runnability and durability by using a vinyl chloride/vinyl acetate copolymer and a specific hydroxyl group-contg. modified polyurethane resin. as a binder. CONSTITUTION:A binder consists of at least a vinyl chloride/vinyl acetate copolymer and a hydroxyl group-contg. modified polyurethane resin. The hydroxyl group-contg. modified polyurethane resin is the hydroxyl group-contg. modified polyurethane resin contg. the hydroxyl group formed by ring-opening of the epoxy group of an epoxy modified polyurethane resin by an amine and/or carboxylic acid at >=0.1mmol/g in the molecular chain and contg. >=3 hydroxyl groups in 1mol. The vinyl chloride/vinyl acetate copolymer refers to a vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinyl acetate/vinyl alcohol copolymer and vinyl chloride/vinyl acetate/maleic anhydride copolymer. Said hydroxyl group-contg. modified polyurethane resin is synthesized by ring-opening of mainly the epoxy group of the epoxy resin expressed by the formula I and epoxy modified polyurethane by an amine or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium having particularly excellent running properties, ii.
The present invention relates to a magnetic recording medium having J Kusumi.

Since audio cassette tapes, which are used as recording media, have recently been used for music recording, there is a demand for tapes with well-developed frequency characteristics and superior sound reproduction capabilities. However, with the widespread use of car stereos, radio-cassette players, etc., there is also a demand for excellent driving performance and durability.

On the other hand, extremely high-density recording has been achieved on video cassette tapes by shortening the recording wavelength and narrowing the track width.

For this reason, there is a demand for tapes with high output, high SZN ratio, and high original picture reproduction ability. Also, the total thickness is 2θμ
While tapes have become thinner than In, the spread of portable VTRs has created demands for VTR tapes that are far superior in terms of running durability compared to conventional tapes.

In short, there is a strong demand for audio and video tapes that have electromagnetic conversion characteristics, runnability, and durability that are even better than those of the past.

For this reason, various binder compositions have been proposed in the past, but at present it is difficult to find one that completely satisfies the above requirements.

Currently, as a binder composition, a mixture of a copolymer of vinyl chloride/vinyl acetate/other vinyl compounds and a urethane rubber resin is used to improve the dispersibility of ferromagnetic powder, the runnability of <tki> properties, and the durability. From this point of view, it is mostly used up.

Examples of copolymers of vinyl chloride/vinyl acetate/other vinyl compounds include vinyl chloride/vinyl acetate/vinyl alcohol copolymers, vinyl chloride/vinyl acetate/maleic anhydride copolymers, etc. is often used because of its excellent dispersibility of ferromagnetic fine powder.

However, when these conventional vinyl chloride/vinyl acetate copolymers, vinyl chloride/vinyl acetate/vinyl alcohol copolymers, vinyl chloride/vinyl acetate/maleic anhydride copolymers, etc. are used, the magnetic layer's Because of the lack of properties, it was necessary to add a large amount of plasticizer or to use a large amount of soft resin. However, when a large amount of plasticizer is added, problems such as blooming and decreased durability of the magnetic layer tend to occur, and when a large amount of polyurethane resin is used together, ferromagnetic powder Dispersion deteriorated and runnability problems tended to occur at high temperatures and high humidity.

Therefore, in the combination of conventional vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinyl acetate/vinyl alcohol copolymer, or vinyl chloride/vinyl acetate/furnace water maleic acid copolymer, and polyurethane fV411t1, It has been difficult to obtain a magnetic recording medium that satisfies the current requirements for sufficient runnability and durability.

Therefore, the present inventors have conducted extensive studies on the bonding of vinyl chloride/vinyl acetate copolymers and various polyurethane resins, and have found that the above-mentioned drawbacks occur when a specific hydroxyl group-containing modified polyurethane resin is used. The present invention was developed based on the fact that it can be erased on a day-to-day basis.

The first purpose of Kibakko is to provide a new magnetic recording medium.

To provide Maki 2 with a magnetic recording medium with excellent magnetic characteristics.

Thirdly, it is an object of the present invention to provide a magnetic recording medium having excellent running properties and Alt durability.

The third objective is to provide a magnetic recording medium with excellent stability of magnetic properties over time in a system using ferromagnetic metal powder.

Fifth, it is desirable to provide a magnetic recording medium that does not produce tape squeal in extremely high temperature and high humidity environments and has stable output.

That is, the object of the present invention is to form a ferromagnetic material (
1: A magnetic layer with fine powder dispersed in a binder is provided (
The binder (d) is composed of at least a vinyl chloride/vinyl acetate copolymer and a hydroxyl group-containing modified polyurethane resin, and the hydroxyl group-containing modified polyurethane resin binds the epoxy groups of the epoxy-modified polyurethane resin to amines and/or Alternatively, a hydroxyl group is generated by ring opening with a carboxylic acid, and the hydroxyl group is added to the molecular chain by 0.
/mmo/2 or more, and contains 3 or more hydroxyl groups in the molecule
This is achieved by using a magnetic recording medium made of a modified polyurethane resin containing hydroxyl groups or more.

Jπ vinyl/vinyl acetate system/copolymerization used in the present invention (1. vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinyl acetate/vinyl alcohol li-copolymerization and
It is a vinyl chloride/vinyl acetate/maleic anhydride copolymer.

The vinyl chloride/vinyl acetate copolymer used in the present invention includes vinyl chloride A O-71wt, vinyl acetate 2-
A proportion of ≠Ow i % is preferable, and a proportion of vinyl chloride of 70 to 2 Iwtφ and vinyl acetate of 30 to jwt% is particularly preferable.

Vinyl chloride/vinyl acetate/vinyl alcohol copolymer used in the present invention; c) vinyl chloride;

It is preferable to have a ratio of ~97 wt., vinyl acetate: 0 to 30 wt., and vinyl alcohol: 3 to 96 wt. Kyoto, vinyl chloride gO~90wt%, vinyl acetate O+-7O
A copolymer of Wt and vinyl alcohol 1S-715-7O is preferable because it provides good dispersion of ferromagnetic powder.

The vinyl chloride/vinyl acetate/fury anhydride/acid copolymer used in the present invention includes 60 to 7 wt% of vinyl chloride, θ to 3θ wt% of vinyl acetate, 1 to 10 wt% of maleic anhydride.
A ratio of 1:1 is preferred.

In particular, vinyl chloride 10 ~ θwt, vinyl acetate θ ~ /
It is preferable that the ferromagnetic fine powder is well dispersed in a co-JE composite of 10 wt% and 10 wt% of sulfur water maleic acid.

The Bq degree of these combined vehicles is preferably about 200 to 700, particularly preferably 300 to 200.

Vehicle chassis (If BH is less than about 200, it will be easily thermally decomposed, and if it is more than about 700, the solubility in bath additives will deteriorate and 5Jj
4if? This is not preferable because the dispersion of the fine powder becomes worse.

Also, the molecule ii distribution (MW/MN) is 1. θ~3.0 is preferable. Here, MW is the weight average molecular weight, and MN is the number average molecular weight.

The hydroxyl group-containing modified polyurethane resin used in the present invention does not have a hydroxyl group at the end of the skeleton molecule, and the epoxy group of the epoxy modified polyurethane resin is ring-opened with an amine or a carboxylic acid to generate a hydroxyl group, Modified polyurethane resin containing o, immo 7/9 or more hydroxyl groups in the molecular chain and 3 or more hydroxyl groups in one molecule,
The epoxy mJll'd component is a compound represented by formula (I).

The above-mentioned hydroxyl group-containing modified polyurethane resin is mainly an epoxy resin represented by formula (I).

The epoxy group of epoxy-modified polyurethane, which is a reaction product with diincyanate such as Hiro'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and hexamethylene diisocyanate, can be replaced with amines such as dimetathuramine, jetanolamine, and diisocyanate. It can be developed and synthesized using dialkanolamines such as brovanolamine, or carboxylic acids such as oxycarboxylic acids such as hydroxystearic acid and hydroxymyristic acid.

Furthermore, the number of hydroxyl groups in the hydroxyl group-containing modified polyurethane resin/molecule used in the present invention is 3 to 3! Personal preference ≠
~, about 25 molecules, and the molecular weight is s, ooθ~ioo
, ooθ preferably g, o.

Something of the order of o-1so or oOo is good.

The above hydroxyl group-containing modified polyurethane resin differs from conventional polyurethane resins in that it has a hydroxyl group in its molecular chain, and due to the synergistic effect of the bisphenol skeleton of the epoxy resin, it improves the dispersibility of magnetic powder and the magnetic coating III. It is thought that heat resistance and hydrolysis resistance are improved, but it is not certain.

In the present invention, it is preferable to use polyisocyanate as a binder.

The polyisocyanate used in the present invention is a reaction product of 3 moles of diisocyanate such as tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate and 1 mole of trimethylolpropane, a reaction product of 3 moles of hexamethylene diisocyanate, fucyanate, etc. These include a biuret adduct compound, an incyanurate adduct compound of 3 moles of tolylene diisocyanate and 2 moles of hexamethylene diisocyanate, a polymer compound of diphenylmethane diisocyanate, and inphorone diisocyanate.

These compounds □9 products 1" J Nippon Polyurethane KK are available under Western product names such as "Coronate L,""Coronet) HL J,""Coronate2o3o,""Millionate M R, J, [Millionate to 4 T LJ, etc.] , Sumitomo Bayer Urethane I (from K Company, "Tesmodule L", [Tesmodule NJ, RF Module ILJ, [Desmodule Lj, etc.), ) D-10,zJ, [Takenate I]-
/10N'' and ``Takenate D--20, 2j'+9'', respectively.

Vinyl chloride/vinyl acetate copolymer, vinyl chloride/RT
= rl'! ! The proportion of vinyl/vinyl alcohol copolymer or vinyl chloride/vinyl acetate/maleic anhydride copolymer and hydroxyl layer dynamically modified polyurethane resin is determined by weight! :! ~30 near 0 is good, especially 90:
/ 0-! ;0:! ;0 is preferred.

Furthermore, when an inocyanate compound is used in combination, it is preferable to use the inocyanate compound in an amount of about 1% to 30% by weight, particularly preferably 1% to 20% by weight, based on the ferromagnetic fine powder.

The total amount of these binders is IO−≠
It is convenient to use Ow, especially /j-30W
T-person is preferable.

In the present invention, it is also possible to use a plasticizer, a stabilizer, and a lubricant in combination. For more information on these additives,
It[
2 are listed.

The recording medium of the present invention is manufactured by applying and drying a magnetic coating material containing a binder composition, ferromagnetic powder, additives, etc. dispersed together with a specific solvent on a support.

As ferromagnetic powder, K-Ti'e203, Fe3O4,
In addition to co-modified iron oxide, modified barium-ferrite, and modified strontium ferrite, alloy fine powders containing iron as a main component are particularly clever.

In addition, the shapes of these ferromagnetic fine powders include acicular, granular,
Particularly preferred are plate-shaped and rice grain-shaped ones.

In addition, +i4'ii W powder has a specific surface area (SBET)
/Evening~, it is preferable to use 200m2/9, LI14'? K specific surface area is 20~/00m2/
9 is preferred.

If the specific surface area is less than m2/9, noise will increase, which is not desirable. Good luck, the specific surface area is λθOm2/f? If it is more than that, the magnetic susceptibility (σS) becomes too low, which is not preferable.

In particular, the binder composition according to the present invention has a specific surface area of 20 m
It was found that the dispersibility and durability of magnetic materials of 279 or higher are improved. Furthermore, the effect V, which is the object of the present invention, could not be obtained by using the hydroxyl group-containing modified polyurethane alone or in combination with a polyisocyanate compound.

Details of ferromagnetic powder, additives, organic solvents, dispersion, coating methods, etc. j goo 4L1.,
It is described in Publication No. 0// etc.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

In addition, in the actual &i+i examples, "parts" indicate "parts by weight."

Example 1゜r''F e 203 (l(c≠000e, acicular ratio 10//, average particle length 0., 1.tam.

SnFJT22m2/9) / 00 parts vinyl chloride /
Vinyl acetate copolymer (polymerization ratio 7:/3, degree of polymerization 20°, molecular weight distribution 2.♂) The light used is shown in Table 7.

Hydroxyl-based modified polyurethane resin (molecular weight: io, ooo: hydroxyl group content in the molecular chain: OO)/2. /Number of hydroxyl groups in molecule: 6) The amounts used are shown in Table 1.

Oleic acid 2 parts Dimethylpolysiloxane (degree of polymerization about 60) 0 parts Butyl acetate 2 parts The above composition was mixed and dispersed in a ball mill for f,≠r hours, and then filtered through a filter having an average pore size of 3a. A magnetic layer coating solution was obtained.

The resulting coating liquid was applied onto a polyethylene terephthalate film with an IEX size of 7a using a reverse roll so that the dry thickness was 5'u.
Magnetic field alignment treatment was performed using a Gaussian electromagnet, and the material was dried. After drying, the magnetic layer was smoothed by sous-ξ-calendering. This was slit to obtain an audio cassette tape (Philips type Co/Pact cassette) having a width of 3°♂lrrrm.

The properties of the obtained tapes are shown in Table 1, Sample No. 3.

Comparison Example 1 Instead of using a modified polyurethane resin containing hydrophilic groups, conventional S!
l) Urethane resin (Dainichi Ink Chemical Co., Ltd. “Chris Bono 7
．． A cassette tape was obtained using KL in the same manner as in Example 1, except that 209'') was used. The obtained results are shown in Table 1, Samples C-t to C-2.

Example 2 Vinyl chloride/vinyl acetate/vinyl alcohol copolymer was used instead of the actual dry vinyl chloride/vinyl acetate copolymer (polymerization ratio 0: 3.M, 30° molecular weight distribution 7.3)
An audio cassette tape was obtained in the same manner as in Example 1, except that . The characteristics of the obtained tape are
Shown are 7 sample cups.

Comparative Example 2 Instead of the vinyl chloride/vinyl acetate copolymer of Comparative Example 1,
Vinyl reinforced/vinyl acetate/vinyl alcohol copolymer (
N-total ratio 0 near:, 3. M times 30, molecular i ψ distribution /
An audio cassette tape was obtained in the same manner as in Comparative Example except that 3) was used. The # capacity of the obtained tapes is shown in Table 1, sample cups C-3 to C-B.

Example 3゜ Co-bentride iron oxide (Co3, Oatomic% deposition.

Fe□1. <t　, HcloOe　.

Acicularity ratio 10//, average particle length o, 4tam, 5nET, 27m2/9)/
oo part Vinyl chloride/vinyl acetate/maleic anhydride copolymer (1F combination ratio 0:1, polymerization degree μ).

The amount used is the hydroxyl group-containing modified polyurethane resin shown in Table 2 (molecular weight/ta, hydroxyl group content in molecular button 1rm mot/9).

The amount used is shown in Table 2: 2 parts of olein [・2-ethylhexyl stearate o, rBα-alumina (XP-average particle size O, Sμ)] and 2 parts of punal acetate. O O
After cross-dispersing the above component A11 in a ball mill for a long time, a polyisocyanate compound (Japan Polyurethane K
Solid dispersion method 1 shown in Table 2 was added to the solid-state dispersion method 1 shown in Table 2 and cross-dispersed for an additional 7 hours.

The mixture was filtered through a filter having an average pore diameter of /μ to obtain a magnetic layer coating solution. The resulting magnetic paint was applied to a polyethylene terephthalate film with a dry thickness of J/4+-μ! Apply with a reverse roll so that it becomes μ,
A magnetic field orientation treatment was performed using a 3000 Gauss magnet while the coating layer was not yet applied, and the film was dried.

After drying, supercalender treatment was performed to smooth the magnetic layer. The tape was slit to obtain a 2-inch [1] video cassette tape (VHs type video cassette). The characteristics of the obtained videotape are shown below in Table 2 Sample/1f110~! , 2.

Comparison Example 3 Instead of the hydroxyl group-containing modified polyurethane resin, a conventional polyurethane resin (Inu Nippon Ink KKW) was used.

A video cassette tape was used in the same manner as in Example 2, except that a video cassette tape ("Chrisbon 7.207") was used.

The obtained results are shown in Table λ Sample &C-7 to C-ri.

Example 4 In place of the Co-coated beltride iron oxide of Example 3, Fe-based alloy powder weight Fhii''e:Ni:Zn:Cr=9
3. I:4l-0jt:/, 2:0. evening.

HC/300 (k, acicular ratio 10//, average particle length 0.3
A videotape was obtained in the same manner as in Example 3, except that U, 811F, and Tg θm2/9) were used. Kuni shows. F, here I) Tooc the sample Tsuta/3 and Sample Ni/Hiroshi tapes.

After storing it for a week, the tape B
When m was determined as d(ll), the coefficients of g, j, g, and θ were decreased compared to the sample before treatment.

Comparative example 4゜ Comparison j + 13 Co-coated beltlide iron oxide replaced with F
e-based alloy fine powder (weight ratio Fe:Ni:Zn:Cr-23
, f: g,! r: /, J: 0, j
A videotape was obtained in the same manner as fd Comparative Example 2, except that -FIc/30θ (acid ratio/θ//, average particle length 0.3μ) was used. 11 of the videotapes obtained
5 characteristics are shown in Table 2 Sample Shop C-10 to C-//. Here, sample AC10 and sample AC obtained here.
-// tape tooc.

After storing it in an atmosphere of 9oad/week, the Bm of the tape was added by 6111, and compared to the treatment @, each io
, there was a decrease of 10.0.

The measurement methods shown in Tables 7 and 2 are shown below.

<Measurement method> fa) Maximum output level of 3/2 Hz (distortion factor 3) when MOLj/ is set to standard tape as OdB (Reference Fuji Cassette E manufactured by Fuji Photo Film KK)
10KHz saturation output level when reference tape is set to OdB (cl) Audio performance (using 700 commercially available cassette decks) te 2 evening'、C、
, tO%RH, aooCl, and rO%RH, and the winding appearance was evaluated.

A: No disordered winding.

13...7 to 5 decks had winding disturbances.

C: Winding disorder occurred on 5 to 70 decks.

D...1 Disturbance of winding occurred on one or more decks.

(dl level decrease simultaneously with the evaluation of audio running performance /θ) (The decrease in the level of the output of I-1z was evaluated.

A...Less than 3dB B...Less than 4dB C...Less than dB D...2dB or more (e) Dirt After evaluating the running performance, the degree of dirt on the deck head was evaluated.

A: There is no dirt at all, or even if there is, it is difficult to check.9; 1°B: There is some dirt, but it is not a problem.

C: There is quite a lot of dirt.

(fl tape squeal During the running performance test, the presence or absence of tape squeal was evaluated.

A: No tape squeal at all.

B...Temporary occurrence in volumes 7-2.

C...Temporary occurrence from volume 3 to volume ta.

D-: Temporary and constant squealing of 5 or more turns/occurrence of ~- or more turns.

tgl Video output reference tape Output of 'l M I-1z when set to total θ dB (reference tape: VHS tape manufactured by Fuji Photo Film KK, 6111 fixed machine: NV-46oo type manufactured by Matsushita Electric KK).

(hl S/N ratio S/N ratio of 10K-≠MHz with correction (Measurement device: Matsushita Electric KK [NV-A A o o type).

m Video running properties Using a commercially available video cassette deck (VHS type) SO stand, running tests were conducted at 2s0C, 0C, R11, and ≠00C1 and 0H, and jitter and skew were evaluated.

A: No jitter or skew.

[3... Jitter or skew sometimes occurs, but there is almost no problem.

C: Jitter or skew occurs frequently and there is a problem.

(Jl [), O, (dropout) increase When measuring the video runability, an increase in 0, 0, W was simultaneously measured.

A...Increase of less than 10 ke/min B...Increase of less than 20 ke/min C...Increase of less than 30 ke/min D...Increase of 30 ke/min or more (k) Regenerate in methyl life still mode time (minutes) until a significant defect occurs on the screen (measuring device 2 Matsushita Electric KK NV manufactured by K.
-ttoo type).

(11 tape squeal (Same as fl's tape squeal.

According to Table 1, audio cassette tape samples A7 to A using hydroxyl group-containing modified polyurethane resin are:
Tape sample AC-3 using this and tape sample A using conventional polyurethane tester C-/~
Compared to c-a' (excluding sample shop C-3), M
OLJ/j and S(')Llo K are almost the same, and have excellent audio running performance, level drop, dirt, and tape squeal, and are excellent in running performance and durability.

According to Table 2, the videotape sample AIθ~12 using the hydroxyl group-containing modified polyurethane resin according to the present invention
and sample 7613. /II has almost the same video output and S/N ratio as the video tape sample AC7~C-ta and sample AC-10~C-// which used the conventional polyurethane resin 11hK, and also has better video running performance. I
), 0, increase, methyl life, excellent tape squeal, excellent runnability, and durability.

From the above Examples and Comparative Examples, a binder containing a hydroxyl group-containing modified polyurethane resin according to the present invention LM li
It was found that when compared with a conventional inder composition containing a polyurethane resin, 'z has electromagnetic conversion characteristics equivalent to or better than that, and a magnetic recording medium with excellent running properties and durability can be obtained.

Patent applicant: Fuji Photo Film Co., Ltd. Continued from page 1 0 Inventor: 1) Possible person: Ogimachi, Odawara City: 0 Inventor: Masashi Aonuma 2-1 Ogimachi, Odawara City
Fuji Photo Film Co., Ltd. 2-1 No. 1 Fuji Photo Film Co., Ltd. Procedural Amendment 1/Month, Showa 1/Month, 1/Month, 1999 To the Commissioner of the Japan Patent Office 1, Indication of the case Showa N year patent application No. Hs≠02 No. 2, Title of the invention Magnetic recording medium 3, Relationship with the case of the person making the amendment Patent applicant Location Name (52), 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture
0) Fuji Photo Film Co., Ltd. 4. Subject of the amendment The description in the "Detailed Description of the Invention" column 5 of the description and the "Detailed Description of the Invention" section of the description of the amendment will be amended as follows.

(1) Page g " ” (■) 2) Page 72, line φ "Magnetic recording medium" "Magnetic recording medium" 1 Correct.

3) Page 73, line 3 "-hydroxyl group-containing modified polyurethane" "Hydroxyl group-containing modified polyurethane resin" and correct it.

(4) No. 20, line 20 "Ferromagnetic fine powder" "Ferromagnetic fine powder" and correct it.

Claims (1)

[Claims] In a magnetic recording medium comprising a magnetic layer on a non-magnetic support in which ferromagnetic fine powder is dispersed in a binder, the binder is made of at least a vinyl chloride/vinyl acetate copolymer and a hydroxyl group-containing modified polyurethane resin. When the epoxy group of the epoxy-modified polyurethane resin is ring-opened with amines and/or carboxylic acids, the hydroxyl group-containing modified polyurethane resin generates a Wednesday group, and the hydroxyl group is added to the molecular chain at 0, /mmot/P. A magnetic recording medium characterized in that it is made of a hydroxyl group-containing modified polyurethane resin containing the above and containing three or more VCs per molecule.