JPS58146024A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the surface smoothness, etc., by forming an underlayer made of a specified radiation-curing resin on a substrate. CONSTITUTION:A substrate is coated with a radiation-curing coating material contg. at least 2 kinds of compounds selected from 0-90wt% radiation-curing compound (A) having >=2 unsatd. double bonds and >=5,000mol.wt. 0-80wt% radiation-curing compound (B) having >=1 unsatdd. double bond and 400-< 5,000mol.wt., and 0-50wt% radiation-curing compound (C) having >=1 unsatd. double bond and <400mol.wt., and by irradiating the coated substrate, three- dimensional cross-linking is caused. The resulting film is then coated with a magnetic coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial method for manufacturing a magnetic recording medium that has excellent wear resistance and surface smoothness, and has good electrical properties.

Currently, many magnetic recording media such as cassette tapes, open reel tapes, video chips, magnetic cards, and magnetic tapes are manufactured using iron oxide on base films such as polyester film, polyvinyl chloride film, polyacetate film, and paper. Coating materials such as paints and printing inks containing magnetizable metal oxides or metal materials (paints will be explained below as an example), orientation,
It is obtained through drying and curing process as required, and vinyl chloride copolymer, polyurethane, polyacrylic acid ester, sometimes epoxy resin, etc. are used as the resin paint binder, and depending on the purpose, plasticizer, rubber, etc. Generally, dispersants, antistatic agents, pigments, etc. are blended.

Various types of binders can be used, but hardening binders such as thermosetting resins are preferred because of their physical properties such as abrasion resistance, heat resistance, and heat resistance.

For magnetic recording media such as magnetic recording tapes, one of the very important characteristics is the adhesion between the base material, such as a polyester film, and the magnetic coating film applied thereon. If this adhesive strength is weak, the magnetic coating may peel off when some force is applied to the magnetic recording chip 7, for example, if a strong momentary stress is applied to the tape. As a result, it becomes impossible to record the peeled portion, and furthermore, recorded information may be lost. In order to increase the impact force with polyester films, etc., chemical treatments of polyester films, surface roughening, and general treatments such as corona perforation have been devised. On the other hand, polyester films used in magnetic recording tapes are crystalline polymers and have low polarity, so it is difficult to adhere to polyester films. Furthermore, the applied magnetic paint has a high pigment concentration and cannot sufficiently cloud the surface of the polyester film, etc., which further reduces the adhesive strength.

On the other hand, as a highly effective method for increasing adhesive strength, a so-called undercoat treatment is being considered in which a resin solution is applied onto a polyester film and a magnetic coating is further applied thereon. However, in this case, when applying the magnetic layer, the undercoat layer already formed on the film is swollen by the organic solvent in which the magnetic paint is used, resulting in uneven coating. Since the film was deposited on the surface of the paint film, there was an amorphous condition that caused lachrymal fluid to drip down. Additionally, if a thermosetting resin is used as an undercoat to eliminate RTV, the heat treatment during curing will cause the undercoat resin or unreacted materials of the curing agent to become thermally softened, causing winding (overlapping). Monkey's Ibis,
It has been difficult to put this into practical use because the undercoat layer sticks to the base film. However, in the case of heat curing, there are problems with the pot life of the lacquer and because heat curing takes time, it is not possible to continuously form a magnetic layer on the top layer.

In order to eliminate such drawbacks, the inventors of the present invention provide each undercoat layer (undercoat)! Radiation curable resin is applied to the oil, an undercoat layer is applied, an excessive drying process is applied as necessary, and radiation is applied.
Very favorable results were obtained by creating a three-dimensional cross-section using radiation and then applying a magnetic layer thereon. According to this method, since the seven-layer coating layer is already crosslinked at the time when the magnetic layer is provided, it is not swollen by organic solvents, and furthermore, the magnetic paint can be applied immediately. Since the surface can be painted, the process can be made more continuous and simplified.

Furthermore, even if the radial net irradiation edge is wound up, the undercoat layer is already hardened, so it has the advantage that it can be stored without causing stickiness. If a radiation-curable resin is used as an undercoat resin for this resin, all the disadvantages of conventional undercoat treatments can be eliminated.

The radiation-curable resin used in the present invention is one that generates diradicals by irradiation, crosslinks, or polymerizes.
] It refers to a substance containing one or more unsaturated 2N bonds in its molecular chain, which causes it to harden.

The radiation curable resin used for the undercoat must have good adhesion to the oliester film, which can be prepared by converting a thermoplastic resin into a radiation curable resin.

As a result of intensive research in order to solve the above-mentioned problem of 1-limer processing of magnetic recording media, the present inventors have discovered that by performing climber processing using the radiation-1Ise-forming handle side, it is possible to achieve short fd.
(1) Forming a primer with extremely good solvent resistance and adhesive properties, and obtaining a magnetic recording medium with excellent surface smoothness and electrical properties. The present invention was developed.

That is, in this invention, after applying a non-magnetic undercoat layer to a support,
In the magnetic recording body formed by forming a magnetic layer, the undercoat υ layer is a compound having a molecular weight of 5,000 or more, preferably 8,000 or more and having two or more unsaturated double bonds that are curable by radiation, 0 Radiation 1@
A compound having a molecular weight of 400 or more and a diameter of 5,000 degrees, preferably 600 to 300 degrees; () A compound having a molecular weight of less than 400 and having one or more unsaturated double combinations that are curable by radiation; (6) above; Φ
This is a magnetic recording medium formed by radiation irradiation using a radiation-curable paint containing at least two or more selected from the following.

Furthermore, radiation-curable resins (5), (B), (C)
(5)
is 0 to 901#, direction is 0 to 80% by weight, C) is 0 to 5
This is a magnetic recording medium with a total ratio of 1 to 0% by weight. Further, the radiation-curable paint contains (5) and 6, (A
) is 20 to 95 weight percent, and 0 is 5 to 80 weight percent. It is a magnetic recording medium that uses a rectangular wire. Furthermore, the radiation-curable paint further contains 1 to 103 It% of I#4, and an undercoat layer is formed by ultraviolet irradiation.

Describing the method of the present invention in detail below, first, the compound that forms the radiation-curable resin used in the present invention is a (meth)acryloyl group or the like at the terminal end of the molecule, 1 unsaturated double bond
It is a compound having two or more molecules, and is usually used in combination with compounds having different molecular weights and numbers of functional groups. A suitable example is shown below.

Summer Compounds containing one or more water and water molecules in the molecule - 1 in 1 molecule
Reacting one incyanate group of a polyisocyanate compound of more than one molecule, and then reacting with one or more molecules of a monomer having a group that reacts with the incyanate group and an unsaturated double bond having radiation curability, fI・e.g. propylene/
Polyether (Ateca Polyether P-I Q 00
(Manufactured by Kanitka Co., Ltd.) 1 mole of toluene diisocyanate was reacted with 2 moles of toluene diisocyanate, and then 2 moles of 2-hydroxyethyl methacrylate were reacted to form a fat, 7-reformer with two acrylic double bonds at the end of the molecule. , oligomers or telomers can be produced.

The water used here [containing 1!1-14- or more+
9th, 7decabolyether P-700, Atekapoly
Polyfunctional polyethers such as Polymeg 650 (manufactured by Four-Cola Co., Ltd.); cellulose derivatives such as nitrocellulose, 7-cetylcellulose, and ethylcellulose; ) partially saponified vinyl chloride-vinyl acetate copolymer having hydroxyl groups such as; polypynyl alcohol; olivinyl formal;
0240, Polycaflo 2 ton PCP-0300 (manufactured by Chisso Corporation) polyesters; saturated polybasic acids such as phthalic acid, inphthalic acid, terephthalic acid, adipic acid, succinic acid, and cepatic acid and ethylene glycol,
Diethylene glycol, 1,4-butanediol, 1.
Esters with polyhydric furcols such as 3-butanediol, 1,2-7' robylene glycol, diethylene glycol, 1,6-hexane glycol, neopentyl glycol, glycerin, trimethylol 7' loban, pentaerythritol. tIl polyester resin obtained by bonding; an acrylic polymer containing at least one kind of hydroxyl group-containing acrylic ester and methacrylic ester as a polymerization component.

In addition, the polyisocyanate compounds used here include 2.4-) luene diisocyanate, 2.6-
43-ene diisocyanate, 1,4-xylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, inphorone diisocyanate 7-un-toyates 7 joules L
1 Death module IL (West Germany Bayer AG) 'J
There is a ly.

Examples of monomers having a group corresponding to an incyanate group and an unsaturated double bond capable of forming a fine grain include acrylic or methacrylic acid 2- and methacrylic acid diethyl esters, 2-
Hydroxytulobil ester, 2-cedroxyoctyl ester, and other esters with water FIki; Acrylic alcohol, maleic acid, etc. Contains active hydrogen that reacts with mono- or diglycerides of long-chain fatty acids having unsaturated double bonds, mono- or di-glycerides, and contains unsaturated double bonds that are resistant to radiation. Also included are monomers.

A reaction product of a compound containing one or more epoxy groups in the molecule and one or more molecules of a monomer having an electron beam-curable unsaturated double bond that reacts with the epoxy group, such as glycidyl methacrylate. Thermoplastic*i jer FC acrylic acid containing an epoxy group obtained by radical polymerization was reacted, and an acrylic double bond was pentanted in the molecule through a ring-opening reaction between the carboxyl group and the epoxy group. In addition, prepolymers or oligomers, or polymers that dream of combining unsaturated 231' + 1'' = radiation IvfP in the molecular skeleton by reacting with maleic acid and reacting with carboxyl groups and epoxy groups. , prepolymers, and oligomers.

Examples of compounds containing one or more epoxy groups in the molecule include homopolymers of acrylic esters or methacrylic esters containing epoxy groups, such as glycidyl acrylate and glycidyl methacrylate, or comonomers with other polymerizable monomers; Epicoat; 828, Epicote 1
001, Epicoat 1007, Ehiko 1009 (manufactured by Shell Chemical Co., Ltd.) and various other types of epoxy shelves.

Groups that react with epoxy groups and radioactive unsaturated 21
Monomers with one bond include acrylic thread monomers containing 6 carboxyl groups such as acrylic acid and methacrylic acid, and acrylic thread monomers containing primary or secondary amine groups such as methylaminoethyl acrylate and methylaminomethacrylate. In addition to monomers, polybasic acid monomers having radiation-curable unsaturated double bonds such as maleic acid, heptamalic acid, crotonic acid, and undecylenic acid can also be used.

A reaction product of one molecule of a compound containing one or more carboxyl groups in the molecule and one or more molecules of a monomer having a group that reacts with the carboxyl group and a radioactive IIPable unsaturated double bond,
For example, by reacting glycidyl methacrylate with thermoplastic resin containing carboxyl groups obtained by solution polymerization of methacrylic acid, -acrylic dihydrocarbons are formed in the molecule by a continuous reaction between the carboxyl groups and the epoxy groups, as in Section 2. Examples include resins, prepolymers, and oligomers into which heavy bonds have been introduced.

Compounds containing carboxyl groups t 1 (i+ or more in the molecule) include polyesters containing carboxyl groups in the molecular chain or at the end of the molecule; having radical monomerism such as acrylic acid, methacrylic acid, maleic anhydride, fumar WM, In addition, it is a single homopolymer 1 having a carboxyl group or a copolymer with other polymerizable monomers.

Examples of monomers having a group that reacts with a carboxyl group and a radiation-curable unsaturated 21 bond include glycidyl acrylate and chrycidyl methacrylate.

■ A polyester compound containing a radiation-curable unsaturated double bond in its molecular chain, for example, a saturated polyester consisting of an ester linkage of a polybasic acid and a polyhydric alcohol as described in Section 1. Unsaturated polyester resin containing radiation-curable unsaturated double bonds with maleic acid,
Examples include polymers and oligomers.

The polybasic and polyhydric alcohol fractions of the saturated oropolyester resin can include the compounds listed in Section 1, and the radiation-curing unsaturated compounds include maleic acid and fumaric acid. You can wear leather.

The method for producing radiation-curable unsaturated ester resins is the conventional method, in which a polybasic acid component of 18 J or more and a polyhydric alcohol fat of 1 si are prepared in a nitrogen atmosphere at 180 to 200°C in the presence of a catalyst.
・Dropout dehydration or alcohol reaction, 240-2
A polyester resin can be obtained by raising the temperature to 80 DEG C. and carrying out a condensation reaction under reduced pressure for 1.0 to 1 liter. The content of maleic acid, fumaric acid, etc. is 1 to 40 molti in wiJyx, and preferably 10
~30 mol.

■ Low molecular weight compounds having radiation-curable unsaturated double bonds can also be used depending on the purpose; such low molecular weight compounds include styrene, ethyl 7-acrylate,
Ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1, 6
-hexane glycol diacrylate, 1,6-hexane glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, etc. (compounds in item V are mainly compounds in C)).

The radiation-curable paint in the present invention i can be obtained by using the compounds described in Sections 1 to 5, but if a compound containing an acrylic double bond (with a molecular weight of 400 or more is used alone), However, as the molecular weight increases, electronic hardening properties tend to decrease due to the functional group density, so a higher amount is required, and as the curing properties decrease, the heat resistance also tends to deteriorate. As for the properties, the higher the curability, the lower the properties may be.

On the other hand, in the case of an electron beam curable buffing resin having a molecular weight of 400 ml, the electron beam curable resin has good electron irradiation properties and good solvent resistance, heat resistance, etc., but there is a problem in adhesion.

In this way, when a compound containing an acrylic double bond and having a molecular weight of 400 or more or less than 400 is used alone, it is difficult to obtain an undercoat paint that satisfies the wide variety of properties required for magnetic recording media in a well-balanced manner. Closely related.

In contrast, in the present invention, 211 of compounds with different low molecular weights
By blending the above ingredients, good adhesion and curability can be obtained.

In the present invention, if necessary, a non-reactive solvent is used.Although 4I K flllJ I5ii is not used as the solvent, it is appropriately selected in consideration of the solubility and compatibility of the binder. Toppings include ketones such as acetone, methyl elktone, methyl isobutyl ketone, and cyclohexanone, esters of ethyl formate, ethyl acetate, and butyl acetate, alcohols such as methanol, ethanol, inbanol, and 7'tanol, toluene, and xylene. , aromatic hydrocarbons such as ethylbenzene, ethers such as inpropyl ether, ethyl ether, dioxane, tetrahydro7
Ran, furfural, etc. can be used as a single solvent or a mixed solvent thereof.

The magnetic layer according to the present invention may be based on a vehicle using a thermoplastic resin or a thermosetting gloss resin. It may be formed by irradiation, and the primer and the magnetic layer may be irradiated with radiation at the same time.

The substrate on which the single layer of polymer and the magnetic paint according to the present invention are coated is a polyethylene terephthalate film, which is widely used as a substrate for magnetic recording media. 1 is a polyamide film, and a 7 medium film is used. Especially in the case of polyniskel yarn film, it is possible to use l-axis stretching and bi-axis stretching on a thin basis.
There are many cases where 6 pieces are used and the river is washed away. It can also be used to coat paper.

Radiation related to the present invention! ! *The radiation used for cross-linking and curing of Koka Koka is stock, electron beam with accelerated electron beam as the source, r-ray with 08°iII source, and β with Sr1 as the source.
- X-rays and ultraviolet rays using the rim and X-cell generation cage as radiation sources can be used for convenience. As an irradiation source, it is advantageous to control the amount of absorption, introduce it into the fabrication process line, and use an electron beam or system/outer edge using an electron beam accelerator. be.

The electronic edge properties used when curing magnetic coatings include:
From the viewpoint of penetrating power, it is preferable to use an electron beam accelerator with an accelerating voltage of 100 to 750 KV, preferably 150 to 3 QKV, and irradiate with an absorption amount of 0.5 to 20 megarads.

The radiation curable 1111N of the present invention can also be cured by ultraviolet light by adding a photopolymerization sensitizer. The photopolymerization tv! Conventionally known 1g agents include benzoin-based agents such as silieva benzoin methyl ether, benzoin ethyl ether, α-methylbenzoin α-chlordeoxybenzoin, benzo-7-ernosine, acetophenone bisdialkylaminopenzopheno-7, etc. Ketones, anthraquinone, phenanthraquinone, etc.
Sulfides such as benzyl disulfide and tetramenalthiuram monosulfide can be used. 0.1 to 1 liter per photo1 gold sensitizer hsl113ir
The range of O attack is desirable.

The present invention will be specifically explained below using Examples and Comparative Examples. 7, "moshi" and "su" in VII indicate parts by weight.

Prior to the examples, an example of @belly synthesis will be shown.

Unbalanced fat synthesis example (a) Vinyl chloride/vinyl hexate/vinyl alcohol 93/2
Copolymer 100 with a molecular weight of 18,000 at a composition of 15% by weight
238 parts of toluene and 95 parts of cyclohexanone were heated to 80°C and the following TLII adduct f7.
Added 51i% and further added tin octylate o, oozib,
Add 0.002 parts of hydroquinone, and react at 82° C. in a N2 gas stream until the reaction rate of incyanate (NCO) reaches 9 parts or more. Cool the reaction mixture and add methyl ethyl ketone 238 lli! Interpret. The obtained fallen fat string material is referred to as (a). In addition, the molecular weight of this O gestation is 1920
It is 0.

TDI adduct @tolylene diisocyanate (TLJI) 348 Rei (N
Heat to 80℃ in 1t04 flask in 2 air currents, 2-
Hydroxyethyl methacrylate (2FiEMA) 2
60 parts, tin octylate 0.07 parts, hydroquinone 0
．． 0.5 parts were dropped into a reactor with controlled cooling so that the temperature inside the reactor was 80-85°C, and after the dropping was completed, 3 parts were added at 80°C.
Stir for an hour to complete the reaction. Reaction completed Adolescence 7
After cooling, a white paste-like 2hEMA attack of ↑l)I was obtained.

Resin synthesis example Φ) Saturated polyester machine side (L- manufactured by Dynamite Nobel)
411) 100 parts were dissolved in 116 parts of toluene and 116 parts of methyl ethyl kent, and after raising the temperature to 80°C, 2.84 parts of inphorone diisocyanate adduct synthesized according to Candlestick Synthesis Example (IL) K was added, and octylic acid was added. Tin 0.00
6 parts, further added 0.006 parts of hydroquinone, and added N2
The reaction is allowed to occur at 80° C. in a gas stream until the NCO reaction reaches 90% or more.

Stretched ai + womb delivery force). The molecular weight on this extension side is 20,600.

Resin synthesis example (e) 291.2 parts of dimethyl terephthalate, 291.2 parts of dimethyl isophthalate, 6468 parts of dimethyl maleate, 251.2 parts of ethylene glycol, 364.8 parts of 1.4-butanediol, 1.3- 81.2 parts of butanediol and 4.0 parts of tetra-n-butyl titanate were charged into a reaction vessel, and after a demethanol reaction at 180°C in a N2 gas stream, the temperature was raised to 240-260°C h L, 0.5-1 rr
A molecular weight of 80oO was obtained by combing reaction under reduced pressure of rnHg.
An unsaturated polyester lateral mass was obtained.

Resin synthesis example (d) 250 parts of NIAX Vol.
24h, Put 33 parts of tin octylate (J, 0. After the completion of the fermentation, react at 80°C until the NCO5 response becomes 95% or more.
shall be.

The molecular weight of this -BV is 1140.

Super fat synthesis %l (e) 148 parts of phthalic anhydride, 65 parts of 1.3-butanediol,
30 parts of ethylene glycol juice and 2.5 parts of para-toluenesulfonic acid were placed in a reaction vessel and heated to 150 parts under a stream of N2 gas.
After an esterification reaction at 180°C for 1 hour and 5 hours at 180°C, it was cooled to 100°C, 0.3 parts of hydroquinone and 28 parts of an acrylic plate were added, and the esterification reaction was carried out for 15 hours to obtain a molecular weight of 2.
000 oligoester acrylate was obtained.

Resin synthesis example (f) 250 parts of Ateka Polyether P-1ooo (polyether manufactured by Jiryuka Co., Ltd.), 65 parts of 2-hydroxyethyl methacrylate, 0.013 parts of hydroquinone, and 0.017 parts of tin octylate were placed in a reaction vessel. After heating and melting at 80℃, T
87.0 parts of LII was cooled to a temperature of 80 to 90°C in the reaction vessel, added dropwise, and after the dropping was completed, N was added at 80°C.
The reaction is allowed to occur until the GO reaction rate reaches 95% or more. The obtained apple fat #1'1 is designated as (f). This extremely fat molecule
i is 161O.

(Example 1) 40 parts of the above a fat (a) 4 parts solvent (toluene/methyl ethyl ketone = 1/1)
56 parts of the above composition for a radiation-curable undercoat II! It was made by the department tilll.

This first material was dried on a polyester film.
Using an electrocurtain-type sacral accelerator manufactured by KEfsI, the acceleration voltage was 160 KV*, the polar current was 10 mA,
Irradiation P warehouse 3 M 5 y )” (F) Condition Te N atmosphere
Irradiate electron 1Fi1t- under the air! # Harden the membrane 7
Raima became even more popular.

Next, the following magnetic material was poured onto this and dried fl#m
Examine the U-plane smoothing process and re-° to 1/2 inch width.
L, a videotape (sample Φ1) was obtained.

Manufacturing method of magnetic material Nitrocellulose (Asahi Shisho Co., Ltd. #)il/2')
8 Autopsy VAGH (Union Carbide u) 10 parts Urethane Enstomer (Gutudochic Co., Ltd., Ester 5703) 9
Part methyl isobutyl ketone 150 parts Cyclohexanone 50 parts Magnetic powder (cobalt-coated iron oxide) 100 parts α-At
O (0.5μ granules) 21u3 Lubricant (high-grade fatty modified silicone oil) 1 part dispersant (
Soybean oil refined lecithin) A magnetic paint was prepared by dispersing the lecithin in a 3 m pipe and dispersing it in a ball mill for 24 hours.

Implementation 91.12 The above alkaline composition 0 7 parts NK ester-A-4G (Shin Nakamura Chemical #) 3 parts solvent (toluene/
Methyl ethyl ketone = 171) 901 IS above, i! 1
The kite mixture was thoroughly mixed and dissolved to prepare a radiation-curable undercoating paint.

Dry this paint on a polyester film mBk5O12
After coating and drying, the amount of irradiation is 5
A single layer of ice bridge-hardened polymer was prepared by electron S heat irradiation under the NJ atmosphere under the following conditions. Next, a magnetic layer was provided in the same manner as in Example 1 to produce Video Team 1 (sample φ2).

Implementation group; j3 6 parts of the above tatami composition (e) 311S1.6 hexane glycol diacrylate 1 part of solvent (toluene/
(Methyl ethyl ketone = 1/1) 90 parts The above-mentioned paper mixture was thoroughly mixed, and 1. I did lk. Dry this t-material on a polyester film so that the thickness is 0.1 μm on the t-cloth L1.
After drying, N under the conditions of
2 Negative under atmosphere.

The fibers were subjected to crosslinking, crosslinking and curing, and a climber's suit was prepared. Next, a videotape (sample φ3) was produced using the same method as in Example 1 except that the magnetic layer was damaged.

Meishi 1-Tori 4 47 parts of the above-mentioned m fat cord evil substance (a) 3 parts of the above-mentioned Tung fat introduction and substance (f) 3 parts Benzophenone 0.3 parts Triethanolamine 0.1 part Solvent (toluene/methyl ethyl ketone = 171) 50 parts The above-mentioned Group M was mixed and dissolved to prepare a coating material for undercoating. This paint was applied onto a polyester film to a dry thickness of 0.5μ, and dried.
The coating film was cured by irradiating purple IA at a line speed of 10 tH per minute under a high-pressure mercury lamp (output sow/g effective tube length 1 cm).

Next is fruit @ ? J+ 1 was coated with a degrading agent on it, and the surface of the film was subjected to a cleaning treatment, and one copy was cut into 2-inch pieces to obtain a videotape (sample Φ4).

Example 5 Said φ measurement power (d) 10 parts NK ester A4G (i, Nakamura Kagakusha) 10 parts pentwin ethyl ether 0.3 parts Solvent (toluene/methyl ethyl ketone = 1/1) 8 (1 above 1
k
[did. A "videotape" (sample φ5) was prepared in the same manner as in Example 4, except that this phlegm was coated on a polyester film to a thickness of 0.2 μm.

Comparative Example 1 Vinyl chloride/vinyl acetate copolymer (Union Carbide Co., VAG) 10
Partial solvent (toluene/methyl ethyl ketone = 171)
90 parts of the above composition was mixed and dissolved and applied to a polyester film to a dry thickness of 0.5 μm, dried to form an undercoat and layer.
A videotape (sample A) was prepared with a magnetic layer provided by the method of TeIJ.

Comparative Example 2 A piece of the acupuncture material of Example 11 was applied to a polyester film without a primer, and after drying and brightening, the surface was smoothed, cut into 1/2 inch width, and videotape ( Sample B)
I got it.

Comparative Example 3 Said side fat assembly (a) SO part solvent (toluene/methyl ethyl ketone = 1/1) 5
0 copies The above composition is mixed and translated into a perforated one-line curing paint, and! j! Do? Video Chi 1 (
Sample C) was produced.

Ratio*9 Example 14 NK Ester A-4G (Shin Nakamura Chemical) 10 parts Solvent (Toluene/Methyl Ethyl Ketone = 171)
89.5 parts benzoin ethyl ether
I made a videotape (U material D) using the same method as the one I used with M9r+4 and the other method.

Example 6 7″ on polyester film as in Example 3 and rfA.
A single layer of lime was provided. Then, radiation 11 of T1! A hardenable magnetic material was applied onto this, dried, and after fC, a surface smoothing treatment was performed and irradiation was performed using an electrocurtain type sensor made by ESI and a beam accelerator at an acceleration voltage of 160 KV, an electrode current of 10 mA, and irradiation. Under the conditions of grade 5yL, N, J
A magnetic layer was provided by irradiating the material with an electron beam and curing it in an ambient atmosphere. Next, the videotape (sample φ
6) was obtained.

Method for producing radiation-curable magnetic paint Magnetic powder (cobalt-coated iron oxide) 120 parts Said side fat composition (a) 15 parts (Solid Bunkoshu) Said side B = Fukunari Isei d) 15 parts (E) Calculated for 1 type) Lubricant 02
Part α-AL203 (0.5 parts granular) 2
Partial solvent (methyl ethyl ketone/toluene = 1/1)
2001iS The mixture of the above assembled materials was milled in a ball mill.
A radiation-curable magnetic paint was prepared by dispersing 24:1'&Iij.

Comparative Example 5 The radiation-curable dye of Example 6 was applied to a polyester film without providing a single layer of primer, and treated and cured in the same manner as in Example 6. Then, one copy was cut into a 2-inch width to obtain a videotape (sample φE).

For videotape samples φ1 to φ6 and φA to φE, peel strength ff (adhesion) of coating group and V HS video f
Table 1 shows the results of measuring y*te(D video hW (R, F'4MH2).

## Regarding adhesion, all samples with extensive undercoat treatment had higher values than those without treatment (ΦB), but those using a compound with a molecular fi of less than 400 (
φD), the effect of using a high molecular weight component in combination with a low value was confirmed. In addition, the samples subjected to the radiation curing treatment according to the present invention had higher values compared to the conventional ones (φA), and it was found that there were no problems with respect to adhesion.

In addition, in the video sensitivity of 4hiH2, the characteristics of the undercoat treated product without bridge hardening treatment (φA) are 1iy lower than the K ratio of the untreated one (φB), and the characteristics of the undercoat treated product without bridge hardening treatment are 1iy lower than that of the untreated product (φB). At this time, the undercoat layer was swollen, which is thought to be because the surface clarity of the magnetic layer was impaired. A similar fine surface was also observed in φC composed of a molecular weight of 8000 or more with a low cross-sectional area and density V. On the other hand, the sample subjected to the radiation hardening treatment of the present invention is easily subjected to surface smoothing treatment, and therefore the untreated sample In fact, an improvement in the characteristics was also observed for the products.

Table 1 Patent Applicant Toyo Ink Manufacturing Co., Ltd. Tokyo City Ki Kagaku Kogyo Co., Ltd. Continued from page 1 0 Inventor Kazushi Tanaka Tokyo Denki Kagaku Kogyo Co., Ltd., 13-1 Nihonbashi-chome, Chuo-ku, Tokyo 0 Inventor Osamu Shinoura Tokyo Denki Kagaku Kogyo Co., Ltd., 13-1 Nihonbashi-chome, Chuo-ku, Tokyo ■Applicant: DK Co., Ltd. 13-1 Nihonbashi-chome, Chuo-ku, Tokyo Procedural amendment (voluntary) 1988 December 1st, Mr. Commissioner of the Japan Patent Office 1, Indication of the case, Patent Application No. 16302 of 1982, 2,
Title of the invention: Magnetic recording medium 3, Relationship with the person making the amendment Patent applicant address: 2-3-13 Kyobashi, Chuo-ku, Tokyo Name: Toyo Ink Mfg. Co., Ltd. 5, Contents of the amendment: Amended specification 1 as attached , Title of the Invention Magnetic Recording Medium 2, Claim 1 A magnetic recording medium in which a non-magnetic undercoat layer is applied to a support, and then a magnetic layer is formed, wherein the undercoat 9 layer is formed.

(A) Molecular weight of 5,000 or more, preferably 800, having two or more unsaturated double bonds that are υ-curable by radiation.
(B) A compound having one or more unsaturated double bonds that is curable by radiation and has a molecular weight of 400 or more and less than 5000, preferably 600 to aoo.

C) A compound having a molecular weight of less than 400 and having one or more unsaturated double bonds that is curable by radiation; A radiation curable compound containing at least two or more selected from the above (A), 2), and C). A magnetic recording medium characterized in that it is formed using paint and irradiated with radiation.

2. The radiation-curable paint contains at least two or more selected from (A), (B), and C), and (c)) is O~
90 weight ratio, (B) θ~80 weight ratio, c>-b:.

The magnetic recording medium according to claim 1, wherein the blending ratio is 50 to 50% by weight.

3. The radiation-curable paint contains (6) and), and (
2. The magnetic recording medium according to claim 1, wherein the blending ratio is 20 to 95% by weight of A) and 5 to 80% by weight of CB).

4. The magnetic recording medium according to any one of claims 1 to 3, wherein the radiation is an electron beam.

5 The radiation-curable paint further has a 0.1
4. A magnetic recording medium according to any one of claims 1 to 3, which contains a photopolymerizable sensitizer in an amount of ~10% by weight and has an undercoat p layer formed by irradiation with ultraviolet rays.

3. Detailed Description of the Invention The present invention relates to an industrial method for manufacturing a magnetic recording medium that has excellent wear resistance and surface smoothness, and has good electrical properties.

Currently, many magnetic recording media such as cassette tapes, reel-to-reel tapes, video tapes, magnetic cards, and magnetic disks are manufactured using polyester films, polyvinyl chloride films,
Coating a coating material such as a paint or printing ink containing a magnetizable metal oxide or metal material such as iron oxide on a base film such as a polyacetate film or paper (hereinafter, paint will be explained as an example), It is obtained through the steps of orientation, drying, and if necessary, curing. Vinyl chloride copolymer, polyurethane, polyacrylic acid ester, and sometimes epoxy resin are used as the resin paint binder, and depending on the purpose, plasticizers, rubber, Dispersant, antistatic agent,
Generally, pigments and the like are added.

Although various types of binders can be used, hardening type binders such as thermosetting resins are considered to be more preferable because of their physical properties such as wear resistance, heat resistance, and solvent resistance.

For magnetic recording media such as magnetic recording tapes, one of the very important characteristics is the adhesion between the base material, such as a polyester film, and the magnetic coating film applied thereon. If this adhesive force is weak, the magnetic coating may peel off when some force is applied to the magnetic recording tape, for example, when strong instantaneous stress is applied to the tape. the result,
The peeled off parts may not be able to be recorded, or even recorded information may be lost. In order to increase the adhesive strength with polyester films and the like, various treatments such as chemical treatment of polyester films, surface roughening, and generally corona discharge have been devised.

However, the current situation is that it is difficult to adhere to polyester films and the like used in magnetic recording tapes because they are made of crystalline polymers and have low polarity.

Furthermore, the applied magnetic paint has a high pigment concentration in the paint,
The inability to wet the surface of polyester films and the like is a cause of further reduction in adhesive strength.

On the other hand, as a highly effective method for increasing adhesive strength, a so-called undercoating process is being considered in which a resin solution is applied onto a polyester film and a magnetic coating is further applied thereon. However, in this case, when applying the magnetic layer, the undercoat layer that has already been formed on the film is swollen by the organic solvent in which the magnetic paint is used, resulting in uneven coating. There are disadvantages in that the smoothness of the magnetic layer is lost due to the appearance of grains on the surface of the film, resulting in a decrease in sensitivity. Additionally, in order to eliminate this problem, if a thermosetting resin is used as the undercoat resin, the undercoat resin or unreacted materials of the curing agent will be thermoset due to the heat treatment during curing, resulting in unrolling (
It has been difficult to put this into practical use because the undercoat layer sticks to the base film when the film is overlaid (overlapping). Moreover, in the case of heat curing, there are problems with the pot life of the lacquer and because heat curing takes time, it is not possible to continuously form the upper magnetic layer.

In order to eliminate such drawbacks, the present inventors used a radiation-curable resin as the undercoat resin when forming each undercoat layer, and after applying the undercoat layer, appropriate drying was performed as necessary.

After the treatment, the material was irradiated with radiation to produce three-dimensional crosslinking, and then a magnetic layer was applied thereon, thereby achieving very favorable results. According to this method, the undercoat layer has already been crosslinked before the magnetic layer is provided, so it does not undergo swelling due to organic solvents, and furthermore, the magnetic paint can be applied immediately. The process will be made more continuous and simplified. Also, after radiation irradiation 1
Even after being wound up, the undercoat layer has already been cured, so it has the advantage of being able to be stored without causing stickiness. If a radiation-curable resin is used as the undercoat resin in this way, all the disadvantages of conventional undercoat treatments can be eliminated.

The radiation-curable resin used in the present invention refers to a resin containing one or more unsaturated double bonds in its molecular chain, which is cured by crosslinking or polymerization by generating radicals upon irradiation with radiation.

As a result of intensive research aimed at solving the above-mentioned problems in the primer treatment of magnetic recording media, the present inventors have succeeded in achieving extremely good solvent resistance and adhesive properties in a short period of time by applying a primer treatment using a radiation-curable resin. The present invention has been completed based on the discovery that a magnetic recording medium with excellent surface smoothness and electrical properties can be obtained by forming a primer having the following properties.

That is, in this invention, after applying nine layers of non-magnetic undercoat to the support,
In a magnetic recording medium formed with a magnetic layer, the undercoat layer (A) has two or more unsaturated double bonds that are curable by radiation, has a molecular weight of 5.000 or more, and preferably has a L value of 80.
(B) A compound having one or more unsaturated double bonds that is curable by radiation and has a molecular weight of 400 or more and less than 5000, preferably 600 to 30o.

C) A compound with a molecular weight of less than 400 having one or more unsaturated double bonds that is curable by radiation, the above (8), (B
This is a magnetic recording medium formed by radiation irradiation using a radiation-curable paint containing at least two or more selected from the following. Additionally, radiation-curable paints (
Contains at least two or more selected from A), (B), and (C), and (5) is 0 to 90. Weight section, however) is 0~
The magnetic recording medium has a blending ratio of 80% by weight C) in the range of 0 to 50% by weight. Further, the radiation-curable paint contains (6) and (B) in a blending ratio of 20 to 950 to 95% by weight and 5 to 80% by weight. A magnetic recording medium that uses electron beams for radiation irradiation. Furthermore, the radiation curable paint is further added in an amount of 0.1 to 10% by weight based on the resin solid content.
This magnetic recording medium contains a photopolymerizable sensitizer and has nine undercoating layers formed by ultraviolet irradiation.

Describing the method of the present invention in detail below, first, the compound constituting the radiation-curable paint used in carrying out the present invention has radiation-curable properties such as a (meth)acryloyl group at the end or side chain of the molecule. It is a compound having one or more unsaturated double bonds, and is usually used by blending 211 or more compounds with different molecular weights and numbers of functional groups. A suitable example is shown below.

■ 1 per molecule of compounds that have one or more hydroxyl groups in the molecule.
One incyanate group of one or more molecules of a polyisocyanate compound is reacted, and then a reaction product with one or more molecules of a monomer having a group that reacts with the isocyanate group and one or more radiation-curable unsaturated double bonds, such as propylene. 1 mol of bifunctional polyether (ADEKA Polyether P-1000 manufactured by Asahi Denka Co., Ltd.), which is obtained by adding propylene oxide to glycol, is reacted with 2 mol of toluene diincyanate, and then 2 mol of 2-hydroxyethyl methacrylate is reacted. The resulting resins, prepolymers, oligomers, and telomers having two acrylic double bonds at the molecular ends can be mentioned.

Compounds containing one or more hydroxyl groups used here include ADEKA POLYETHER P-700,7 DECA POLYETHER P-1000゜ADEKA POLYETHER G-1500 (
Polyfunctional polyethers such as Jiryukasha M), Polymeg 1000, and Polymeg 65° (Forker-Oates M); Cellulose derivatives/conductors such as nitrocellulose, acetylcellulose, and ethylcellulose: Vinyl )VAG
Partially saponified vinyl chloride-vinyl acetate co-x combination with a hydroxyl group such as H (manufactured by Union Carbide, USA):
Polyvinyl alcohol; Polyvinyl formal; Polyvinyl butyral; Polycaprolactone PCP-0200
Polyfunctional polyesters such as , polycaprolactone PCP-0240, polycaprolactone PCP-0300 (manufactured by Chisso Corporation); saturated polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, and cepatine and ethylene glycol, diethylene glycol, 1.4-butanediol, 1.3-butanediol,
1゜Acrylic polymer containing at least one kind of acrylic ester and methacrylic ester as a polymerization component, such as 2-propylene glycol, dipropylene glycol, 1,6-hexane glycol, neopentyl glycol, glycerin, and trimethylolpropane pentaerythritol. One example is merging.

In addition, the polyincyanate compounds used here include 2.4-) lyene diisocyanate, λ6-xylene diisocyanate, and 1.4-xylene diisocyanate.
1', m-phenylene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, inphorone diisocyanate and desmodur L,
Examples include Desmodule IL (West Germany Bayeno [Company!R]).

Monomers having a group that reacts with an isocyanate group and a radiation-curable unsaturated double bond include 2-hydroxyethyl ester of acrylic acid or methacrylic acid, 2-
Hydroxypropyl ester% Esters with hydroxyl groups such as 2-hydroxyoctyle, stellate; acrylamide, methacrylamide, N-methylol acrylamide, etc.; □ □ Allyl alcohol, maleic acid polyhydric alcohol ester compounds, unsaturated double bonds These monomers, such as mono- or diglycerides of long-chain fatty acids, which have active hydrogen that reacts with incyanate groups and which contain unsaturated double bonds that have radiation curability are also included.

■ A reaction product of one molecule of a compound containing one or more epoxy groups in the molecule and one or more molecules of a monomer having a group that reacts with the epoxy group and an electron beam curable unsaturated double bond, such as glycidyl methacrylate. A thermoplastic resin containing an epoxy group obtained by radical polymerization is reacted with acrylic acid, and a ring-opening reaction between the carboxyl group and the epoxy group causes
A resin with acrylic double bonds pendant in the molecule.
Examples include prepolymers or oligomers, and resins, prepolymers, and oligomers that have radiation-curable unsaturated double bonds in their molecular skeletons resulting from a ring-opening reaction between carboxyl groups and epoxy groups by reacting maleic acid.

Examples of compounds containing one or more epoxy groups in the molecule include homopolymers of acrylic esters or methacrylic esters containing epoxy groups, such as glycidyl acrylate and glycidyl methacrylate, or copolymers with other polymerizable monomers: Epicote 828; Epicote 1
There are various other types of epoxy resins such as 001, Epicote 1007, and Epicote 1009 (manufactured by Shell Chemical Co., Ltd.).

Examples of monomers having groups that react with epoxy groups and radiation-curable unsaturated double bonds include acrylic monomers containing carboxyl groups such as acrylic acid and methacrylic acid, methylaminoethyl acrylate, and methylaminomethacrylate. In addition to acrylic monomers having primary or secondary amino groups, polybasic acid monomers having radiation-curable unsaturated double bonds such as maleic acid, fumaric acid, crotonic acid, and undecylenic acid can also be used.

■ Solution polymerization of one molecule of a compound containing one or more carboxyl groups in the molecule and one or more molecules of a monomer having a group that reacts with carboxyl groups and one or more radiation-curable unsaturated double bonds, such as methacrylic acid. A resin or prepolymer obtained by reacting glycidyl methacrylate with a thermoplastic resin containing a carboxyl group obtained by the above process, and introducing an acrylic double bond into the molecule by a ring-opening reaction between the carboxyl group and the epoxy group in the same way as in item ①. , oligomers.

Compounds containing one or more carboxyl groups in the molecule include polyesters containing carboxyl groups in the molecular chain or at the end of the molecule, acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc., which have radical polymerizability and have carboxyl groups. These include homopolymers of monomers having groups or copolymers with other polymerizable monomers.

Examples of monomers having a group that reacts with a carboxyl group and a radiation-curable unsaturated double bond include glycidyl acrylate and glycidyl methacrylate.

(2) A polyester compound containing a radiation-curable unsaturated double bond in its molecular chain, such as a saturated polyester compound consisting of an ester bond between a polybasic acid and a polyhydric alcohol as described in item 1. Radiation curable ester resin with maleic acid as part of the polybasic acid.

Examples include unsaturated polyester resins, prepolymers, and oligomers containing unsaturated double bonds.

Examples of the polybasic acid and polyhydric alcohol components of the saturated polyester resin include the compounds listed in Section 1.
Examples of radiation-curable unsaturated double bonds include maleic acid and fumaric acid.

The radiation-curable unsaturated polyester resin is produced by a conventional method, that is, by adding maleic acid, fumaric acid, etc. to one or more polybasic acid components and one or more polyhydric alcohol components, that is, in the presence of a catalyst.
~b♀After dehydration or dealcoholization reaction in an elementary atmosphere,
A polyester resin can be obtained by raising the temperature to 240 to 280°C and carrying out a condensation reaction under reduced pressure of 0.5 to 1.

The content of maleic acid, fumaric acid, etc. in the acid component is 1 to 40 mol, preferably 10 to 30 mol, in view of crosslinking during production, radiation curability, etc.

■ Low molecular weight compounds with radiation-curable unsaturated double bonds can also be used depending on the purpose; such low molecular weight compounds include styrene, ethyl acrylate,
Tirenoglycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,6
-hexane glycol diacrylate, 1,6-hexane glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, etc. (Note that the compound of item v is mainly the compound of (C)).

The radiation-curable paint in the present invention can be obtained by using the compounds described in Items 1 to 5, but when a compound containing an acrylic double bond and having a molecular weight of 400 or more is used alone, As the molecular weight increases, the electron beam curability tends to decrease due to the functional group density, so a high dose is required, and as the curability decreases, the heat resistance also tends to decrease. In addition, the adhesiveness may decrease as the curability increases.On the other hand, in the case of electron beam curable resins with a molecular weight of less than 400, electron beam curability is good and solvent resistance, heat resistance, etc. are good. However, there is a problem with adhesion.

In this way, when a compound containing an acrylic double bond and having a molecular weight of 400 or more or less than 400 is used alone, it is difficult to obtain an undercoat paint that satisfies the wide variety of properties required for magnetic recording media in a well-balanced manner. It's difficult.

- In contrast, in the present invention, two or more types of compounds having different molecular weights are blended, and good adhesion and curability are achieved.

In the present invention, if necessary, a non-reactive solvent is used as the solvent, which is not particularly limited, but is appropriately selected in consideration of the solubility and compatibility of the binder. For example, ketones such as acetone, methyl ole ketone, methyl imbutyl ketone, cyclohexanone, esters such as ethyl formate, ethyl acetate, butyl acetate, alcohols such as methanol, ethanol, isopropanol, butanol, toluene, xylene, Aromatic hydrocarbons such as ethylbenzene,
Ethers such as inflovir ether, ethyl ether, and dioxane, and furans such as tetrahydrofuran and furfural are used as a single solvent or a mixed solvent thereof.

The magnetic layer according to the present invention may not only use a thermoplastic resin or a thermosetting resin as a vehicle, but also one that uses a radiation-curable resin such as that used in Climber monolayers and is formed by irradiation with radiation. It is also possible to irradiate the climber and the magnetic layer with radiation at the same time.

The substrate on which the single layer of primer and the magnetic paint according to the present invention are applied include polyethylene terephthalate film, which is currently widely used as a substrate for magnetic recording media;
Further, for applications requiring heat resistance, polyimide films, polyamide films, etc. are used. Particularly in polyester films, on a thin basis, l-axis stretching,
In many cases, it is used after being subjected to axial stretching treatment. It is also used to coat paper.

The radiation used for crosslinking and curing the radiation-curable paint according to the present invention includes an electron beam using an electron beam accelerator as a radiation source;
γ-rays using CO60 as a radiation source, β-rays using 5r90 as a radiation source
- rays, X-rays from an X-ray generator, and ultraviolet rays are used. In particular, as an irradiation source, it is advantageous to use electron beams or ultraviolet rays from an electron beam accelerator from the viewpoints of controlling the absorbed dose, introducing into the manufacturing process line, blocking ionizing radiation, etc.

The electron beam characteristics used when curing the coating film include an acceleration voltage of 100 to 750, preferably 1
It is convenient to irradiate using an electron beam accelerator of 50 to 300 KV with an absorbed dose of 0.5 to 20 megarads.

The radiation-curable coating material of the present invention can also be cured by ultraviolet rays by adding a photopolymerization sensitizer. The photopolymerization sensitizer may be a conventionally known one, such as benzoin-based sensitizers such as benzoin methyl ether, benzoin ethyl ether, α-methylbenzene, α-chlordeoxybenzoin, benzophenone, and cetophenone binudialkylamino. Examples include ketones such as benzophenone, quinones such as anthraquinone and phenanthraquinone, and sulfides such as benzyl disulfide and tetramethylthiuram monosulfide. The photopolymerization sensitizer is
It is preferably in the range of 0.1-10% based on the solid content of the resin.

The present invention will be specifically explained below using Examples and Comparative Examples. In the two examples, "parts" and "chi" indicate parts by weight.

Prior to Examples, resin synthesis examples will be shown.

Resin synthesis example (a) Hinyl chloride/vinyl acetate/hinyl alcohol 93/2
After heating and dissolving 100 parts of a copolymer with a composition of 1% 15IlrJ and a molecular weight of 18,000 in 238 parts of toluene and 95 parts of cyclohexanone, the temperature was raised to 80°C, 7.5 parts of the following TDI adduct was added, and 0 parts of tin octylate was added. 0.002 parts of hydroquinone and 0.002 parts of hydroquinone were added, and the mixture was allowed to react at 82° C. until the reaction rate of NCO (isocyane in a N-2 gas stream) reached 90% or more. After the reaction is completed, the mixture is cooled and diluted with 238 parts of methyl ethyl ketone. The resulting resin composition is referred to as (a). Note that the molecular weight of this resin is 19,200.

Synthesis of TDI adduct After heating 348 parts of tolylene diene cyanide (TDI) to 80°C in a 1t04 flask in a N2 stream, 260 parts of 2-hydroxyethyl methacrylate (2HEMA) and 0.07 part of tin octylate were added. , hydroquinone 0.05
The mixture was added dropwise while controlling the cooling so that the temperature inside the reaction vessel was 80 to 85°C, and after the addition was completed, the mixture was stirred at 80°C for 3 hours to complete the reaction. After the reaction is complete, take it out, cool it down,
A white paste-like TDI 2HEMA adduct was obtained.

Resin synthesis example (b) Saturated polyester resin (Dynamite Nobel ML-
411) 100 parts of inphorone diisocyanate was dissolved in 116 parts of toluene and 116 parts of methyl ethyl ketone, heated to 80°C, and synthesized according to resin synthesis example (a).
Add 2.84 parts of adduct, further add 0.006 parts of tin octylate, and 0.006 parts of hydroquinone, and add N2
The reaction is carried out at 80° C. in a gas stream until the NCO reaction rate reaches 90% or more.

The obtained resin composition is referred to as (b). The molecular weight of this resin is 2'0600.

Resin synthesis example (e) 291.2 parts of dimethyl terephthalate, 291.2 parts of dimethyl inphthalate, 64.8 parts of dimethyl maleate, 251.2 parts of ethylene glycol, 364.8 parts of 1°4-butanediol, 1, 81.2 parts of 3-butanediol and 4.0 parts of tetra-n-butyl titanate were placed in a reaction vessel, and after demethanol reaction at 180°C in a N2 gas stream, the temperature was raised to 240-260°C at 0.5-1 mHg. By the condensation reaction under reduced pressure, an unsaturated polyester resin having a molecular weight of s o o o a' was obtained.

Resin synthesis example (d) 250 parts of NIAX Polyopoly PCP-0200 (polycaprolactone manufactured by Chisso Corporation), 122.2 parts of 2-hydroxyethyl methacrylate), 0.024 parts of hydroquinone, and 0.033 parts of tin octylate were placed in a reaction can. 80℃
After heating and dissolving, 1163.6 parts of TD was added dropwise while cooling the reaction vessel to a temperature of 80 to 90°C, and after the dropwise addition was completed, the reaction was allowed to occur at 80°C until the NCO conversion rate reached 95% or more. The obtained resin composition is referred to as (d).

The molecular weight of this resin is 1140.

Resin synthesis example (e) 148 parts of phthalic anhydride, 65 parts of 1.3-butanediol,
30 parts of ethylene glycol and 2.5 parts of para-toluenesulfonic acid were placed in a reaction vessel and heated to 150°C under a stream of N2 gas.
After esterification reaction at 180°C for 1 hour and 5 hours at 180°C,
Cooled to 100°C, added 0.3 parts of hydroquinone and 28 parts of acrylic acid, and carried out an esterification reaction for 15 hours, resulting in a molecular weight of 2.
000 oligoester acrylate was obtained.

Resin synthesis example (f) 250 parts of Adeka Polyether P-1000 (polyether manufactured by Mudenka Co., Ltd.), 65 parts of 2-hydroxyethyl methacrylate, 0.013 parts of hydroquinone, and 0.017 parts of tin octylate were placed in a reaction can. After heating and dissolving at 80℃, T
87.0 parts of DI was added dropwise while cooling the reaction vessel to a temperature of 80 to 90°C, and after the dropping was completed, NCO was added at 80°C.
The reaction is allowed to proceed until the reaction rate reaches 95% or more.

The obtained resin composition is designated as (f). The molecular weight of this resin is 1610.

Example 1 40 parts of the resin composition (a) 4 parts of the resin composition (d) Solvent (toluene/methyl ethyl ketone = t/4)
56 parts The mixture of the above compositions was thoroughly mixed and dissolved to prepare a radiation-curable undercoating paint.

After this paint was dried on a polyester film, it was irradiated with an electron beam in an N2 atmosphere using an electrocurtain type electron beam accelerator manufactured by ESI under the conditions of an acceleration voltage of 160 KV, an electrode current of IQ mA, and an irradiation dose of 3 Mrad. death,
The coating was cured and a layer of primer was applied.

Next, the following magnetic paint is applied on top of this, and an orientation treatment is performed.
After drying, the surface was smoothed and cut into pieces of 2 inch width to obtain videotagues (sample≠1).

Manufacturing method of magnetic paint Nitrocellulose (non-chemical H1/2')
8 parts vinylai) VAGH (manufactured by Union Carbide)
10 parts Urethane elastomer (Gutdrich, Ester 5703) 9
100 parts methyl isobutyl ketone 150 parts cyclohexanone 100 parts Magnetic powder (cobalt-coated iron oxide)
Part α-A4203 (□j・5μ granules) 2 parts lubricant (higher fatty acid modified silicone oil) 1 part powder (soybean oil refined lecithin) 3 parts,
The mixture was dispersed in a ball mill for 24 hours to prepare a magnetic paint.

Example 2 The resin composition (C) 7 parts NK ester-A-4G (acrylic monomer manufactured by Shin Nakamura Chemical, molecule 11198) 3 parts Solvent (toluene/methyl ethyl ketone = 1/1) 90 parts A mixture of the above composition The mixture was thoroughly mixed and dissolved to prepare a radiation-curable undercoat paint.

Apply this paint to a polyester film with a dry film thickness of 0.2 μm.
After coating and drying, the irradiation dose was 5M.
A single layer of primer was crosslinked and cured by electron beam irradiation under Rad conditions in an N2 atmosphere. Next, a magnetic layer was provided in the same manner as in Example 1 to produce a videotape (sample +2).

Example 3 6 parts of the resin composition (b) 3 parts of the resin composition (e) 1.6 hexane glycol diacrylate
1 part solvent (toluene/methyl ethyl ketone, = 171)
A radiation-curable undercoat paint was prepared by thoroughly mixing and dissolving 90 parts of the above composition mixture. This paint was applied to a polyester film to a dry film thickness of 0.1μ, and after drying, electron beam irradiation was performed in an N2 atmosphere at an irradiation dose of 2 Mrad to form a single layer of crosslinked and cured primer. Ta. Next, a magnetic layer was provided in the same manner as in Example 1 to produce a videotape (sample +3).

Example 4 47 parts of the resin composition (a) 3 parts of the resin composition (f) 0.3 parts of benzophenone 0.1 part of triethanolamine 50 parts of solvent (toluene/methyl ethyl ketone = 171) The above compositions were mixed and dissolved. A UV-curable undercoating paint was prepared. This paint was applied to a polyester film to a dry film thickness of 0.5 μm, and after drying, it was exposed to ultraviolet light at a line speed of 10 m/min under a high-pressure mercury lamp (output 80 W/effective! length 1 cm). was irradiated to cure the coating film.

Next, the magnetic paint of Example 1 was applied thereon, and after drying, the surface was smoothed and cut into 1/2 inch width to obtain a videotape (sample +4).

Example 5 Said resin composition (d) 10 parts NK
Ester A4G (manufactured by Shin Nakamura Chemical) 10 parts Benzoin ethyl ether 0.3
Partial solvent (toluene/methyl ethyl ketone = 1/l)
801IS The above composition was mixed and dissolved to prepare an ultraviolet curable paint. A videotape (Sample No. 5) was prepared in the same manner as in Example 4, except that this paint was applied onto a polyester film to a dry film thickness of 0.2 μm.

Comparative Example 1 Vinyl chloride/fraudulent vinyl copolymer (Vinylite VAGH manufactured by Union Carbide) 1
0 parts Solvent (toluene/methyl ethyl ketone = 171) 9
A magnetic layer was formed in the same manner as in Example 1, except that a coating material prepared by mixing and dissolving the above composition was applied to a polyester film to a dry thickness of 0.5μ, dried, and an undercoat layer was formed. Piteote 7° (sample A) was prepared.

Comparative Example 2 The magnetic paint of Example 1 was applied to a polyester film without a single layer of primer, and after drying, the surface was smoothed and cut into 2-inch pieces to obtain a videotape (Sample B). .

Comparative Example 3 50 parts of the resin composition (a) 50 parts of solvent (toluene/methyl ethyl ketone = 1/1) The above composition was mixed and dissolved to prepare a radiation-curable coating material, and a videotape was prepared in the same manner as in Example 1. (Sample C) was produced.

Comparative example 4 NK ester-A-4G (manufactured by Shin Nakamura Chemical) 10
Partial solvent (toluene/methyl ethyl ketone = 1/1) 8
9.5 parts benzoin ethyl ether 0.5
The above compositions were mixed and dissolved to prepare an ultraviolet curable paint, and a videotape (sample D) was produced in the same manner as in Example 4.

Example 6 Similar to Example 3, a single layer of brimer was provided on a polyester film. Next, the following radiation-curable magnetic paint was applied on top of the coating, dried, and then subjected to surface smoothing treatment. Using an electrocurtain-type electron beam accelerator manufactured by ESI Co., Ltd., an acceleration voltage of 160 KV was applied to the polar current. A magnetic layer was provided by irradiating and curing with an electron beam in an N2 atmosphere under the conditions of 10 mA and an irradiation dose of 5 Mrad. Then, one copy was cut into a 2-inch width to obtain a videotape (sample divided by 6).

Method for manufacturing radiation-curable magnetic paint Magnetic powder (cobalt-coated iron oxide) 120 parts The above resin composition (a) 15 parts (in terms of solid content) The above resin composition (d) 15 parts (in terms of solid content) Lubrication agent
0.2 parts α-At203 (0.5μ granules)
A mixture of 2 parts solvent (methyl ethyl ketone/toluene = 1/1) and 200 parts of the above composition was dispersed in a ball mill for 24 hours to prepare a radiation-curable magnetic coating.

Comparative Example 5 The radiation-curable magnetic coating of Example 6 was applied to a polyester film without providing a layer of brimer, and treated and cured in the same manner as in Example 6. Then, one copy was cut into a 2-inch width to obtain a videotape (Sample E).

Example 7 As in Example 1, a single layer of brimer was provided on a polyester film. Next, the following thermosetting magnetic paint was applied on top of this, and after being subjected to orientation treatment, drying, and smoothing treatment,
A magnetic layer was formed by heat curing at 60° C. for 48 hours. (Sample≠7) Production of thermosetting magnetic paint Magnetic powder (cobalt coated iron oxide) 100 parts Vinyrite VAGH 15 parts Urethane elastomer (Ester 5703) 1
0 parts methyl ethyl ketone
A mixture of 100 parts methyl in butyl ketone 100 parts toluene 100 parts or more was kneaded in a ball mill for 48 hours, and then 4 parts of Coronate L manufactured by Nippon Polyurethane Co., Ltd. was mixed as a crosslinking agent to prepare a magnetic paint.

Comparative Example 6 In Comparative Example 1, only the formation of the magnetic layer was carried out in the same manner as in Example 7, and the rest was carried out in the same manner as in Comparative Example 1 to obtain Sample +F'.

Table 1 shows the results of measuring the peel strength (adhesion) of the coating film and the video sensitivity (PF4MH2) on a VHS video deck for videotape samples +1 to ≠7 and A-S F.
Shown below.

As for adhesion, all the samples that were properly undercoated had higher values than the untreated ones (S B), but the ones that used a compound with less than t4oo per molecule (S D).
) had a low value, confirming the effect of using a high molecular weight component in combination. In addition, the samples subjected to the radiation curing treatment according to the present invention had higher values than the conventional ones (+A), indicating that there were no problems with adhesion.

In addition, in the video sensitivity of 4MH2, the properties of the undercoat layer without cross-linking hardening treatment (+A) are lower than that of the untreated one (B), and when the magnetic layer is applied, It is thought that the undercoat layer swelled because the surface smoothness of the magnetic layer was impaired. A similar tendency was not observed for ≠C, which was composed of a molecular weight of 500 or more and a low crosslinking density. On the other hand, since the sample subjected to the radiation hardening treatment of the present invention was easily subjected to surface smoothing treatment, the characteristics were actually improved compared to the sample without IC1 treatment.

Table 1 Procedural amendment (spontaneous) 1985 Mon-XX Date Commissioner of the Patent Office 1, Indication of case Patent Application No. 16302, 1988 2
, Name of the invention Magnetic recording medium 3, Relationship to the case of the person making the amendment Patent applicant address 2-3-13 Kyobashi, Chuo-ku, Tokyo Name
Column 5 of "Claims" and "Detailed Description of the Invention" of the Toyo Ink Manufacturing Co., Ltd. Specification, Contents of Amendment 1, Scope of Claims As shown in Attachment 2, Detailed Description of the Invention Explanation (1) Amendment and details of the written amendment submitted on December 24, 1982 (hereinafter referred to as the "amended statement") No. 8
In line 9 of the page, “(A) is 0 to 90% by weight” is changed to “(A) is 0 to 90% by weight”
(2) Corrected specification page 8, No. 13
In the line ``This is the mixing ratio.'' Next to ``In (A) and (C).''

(A) is 50 to 95% by weight, (C) is 5 to 50% by weight, and in (B) and (C), (B) is 50% by weight.
~95% by weight, (C)' in a blending ratio of 5 to 50% by weight, (A), (B) and (C).

(A) is 10 to 90% by weight, (B) is 5 to 90% by weight,
The blending ratio of (C) is 5 to 50% by weight. ” is inserted.

(3) "Electron beam" on page 12, lines 17-18 of the corrected specification
is corrected to "radiation".

(4) "Methylamino methacrylate" on page 14, lines 4-5 of the corrected specification is corrected to "methylamine ethyl methacrylate."

(5) "Electron beam" on page 17, lines 14-15 of the corrected specification
is corrected to "radiation".

(6) "Electron beam" on page 17, line 19 of the corrected specification is corrected to "radiation."

(7) "Electron beam" on page 17, line 20 of the corrected specification is corrected to "radiation."

(8) Insert "(solid content equivalent, hereinafter the same shall apply to the resin composition of the resin synthesis example)" after "40 copies" on page 25, line 10 of the corrected specification.

(9) Before “drying” on page 28, line 20 of the corrected specification, “
"Orientation processing," is inserted.

(lO) Before “drying” on page 30, line 3 of the corrected specification, “
"Orientation processing," is inserted.

(11) Before “drying” on page 31, line 2 of the corrected specification, “
"Orientation processing," is inserted.

(12) "15 parts (solid content equivalent)" on page 31, line 12 of the corrected specification is corrected to "15 parts."

(13) "rls part (solid content equivalent)" on page 31, line 13 of the corrected specification is corrected to "15 parts."

Claims: 1. A magnetic recording medium in which a magnetic layer is formed after a non-magnetic undercoat layer is applied to a support, the undercoat layer comprising:

(A) A molecular weight of 5,000 or more and having two or more unsaturated double bonds that are curable by radiation.

Preferably 8000 or more compounds.

(B) having a molecular weight of 400 or more and having one or more unsaturated double bonds that are curable by radiation.

and less than 5000, preferably 600 to 3000 compounds.

(C) A compound with a molecular weight of less than 400 having one or more unsaturated double bonds that is curable by radiation, the above (A>,
A magnetic recording medium characterized in that it is formed by radiation irradiation using a radiation-curable paint containing at least two or more selected from (B) and (C).

2. The radiation-curable paint contains at least two or more selected from (A>, (B), and (C)).

and (A) is 0 to 95% by weight, and (B) is 0 to 80% by weight.
, (C) in a blending ratio of 0 to 50% by weight.

3. The radiation-curable paint contains (A) and (B),
The magnetic recording medium according to claim 1, wherein the blending ratio is 20 to 95% by weight of (A) and 5 to 80% by weight of (B).

4. The magnetic recording medium according to any one of claims 1 to 3, wherein the radiation is an electron beam.

5 The radiation-curable paint further has a 0.1
Contains ~10% by weight of photopolymerizable sensitizer.

A magnetic recording medium according to any one of claims 1 to 3, in which an undercoat layer is formed by ultraviolet irradiation,
”

Claims (1)

[Claims] 1. A magnetic recording medium in which a magnetic layer is formed after a nonmagnetic undercoat layer is applied to a support, in which the undercoat layer has (f) radiation curability. Molecules having two or more unsaturated double bonds [compounds with a molecular weight of 5,000 or more, preferably 8,000 or more, provided that the molecular weight is 400 or more and has one or more unsaturated double bonds that are curable to radiation, and 5,000 or more 0 A compound having a molecular weight of less than 400 and having one or more unsaturated double bonds that are curable by radiation; At least 2 selected from the above (c)), (B), and Ic) 1. A magnetic recording medium characterized in that it is formed by radiation irradiation using a radiation-curable paint containing at least one species. 2. The radiation-curable paint contains at least two or more selected from Φ) and C), and (5) is 0 to 90% by weight, 0 is 0 to 801jL, and 0 is 0 to 501jL.
The magnetic recording medium according to claim #41, wherein the blending ratio is -. 3. The radiation-curable paint contains ^ and (B), and (8
1. The soft magnetic recording medium according to claim 1, wherein the blending ratio is 20 to 95% by weight) and 5 to 80% by weight. 4. The magnetic recording medium according to any one of claims 1 to 3, wherein the radiation is an electron beam. 5. The magnetic recording according to any one of claims 1 to 3, wherein the radiation-curable paint further contains 1 to 101 t% of photopolymerizable #I sensitizer, and an undercoat layer is formed by ultraviolet irradiation. Medium.