JPS6252364B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic coating material that has not only excellent wear resistance, heat resistance, and hydrolysis resistance, but also particularly excellent dispersibility of magnetic powder, and more particularly relates to a magnetic coating material that is suitable for curing by radiation such as electron beams. In recent years, magnetic paints for magnetic recording are increasingly required to have high performance, and in particular, those with excellent electrical properties are strongly required. For this purpose, it is important to improve the magnetic powder, but the binder used is also an important factor when coating the magnetic powder on a tape support. In particular, if the dispersibility of magnetic powder is poor, it often impairs various performances, including electrical characteristics, such as generating noise and reducing output, so it has the property of dispersing magnetic powder better as a binder. This is one of the most important issues in achieving the above objectives. In addition, maintaining adhesion between the binder and the magnetic powder and between the binder and the base film, which is mainly made of polyester resin, as well as heat resistance and abrasion resistance, are essential properties. Traditionally, binders for paints containing magnetic powder include those using thermoplastic resins such as vinyl chloride copolymers, polyurethane, nitrocellulose, polyvinyl butyral, and saturated polyester, and thermosetting resins such as phenol, urea, melamine, and epoxy. It is common to use plastic resins, and additives such as dispersants, lubricants, abrasives, antistatic agents, etc. are added as necessary. When thermoplastic resins are used as resins for these binders, heat resistance and abrasion resistance are often not fully satisfied. In addition, when using thermosetting resin,
Although the above drawbacks can be made relatively satisfactory,
On the other hand, curing by heating for a long time is necessary to obtain the desired physical properties, and at this time, defects such as a decrease in the surface smoothness of the magnetic layer and thermal deformation of the base film are likely to occur, and furthermore, thermal energy This will also have a negative impact on the total cost due to longer manufacturing times. Furthermore, in order to improve the above-mentioned problems, binders have been provided to improve heat resistance and abrasion resistance by adding compounds that can be cured through chemical reactions, such as isocyanate compounds and epoxy compounds, to thermoplastic resins. There are, but
In this case, the uniformity of the finally obtained magnetic material for magnetic recording is likely to be impaired due to lack of storage stability. In order to solve the various problems mentioned above, recently a new curing method and a method using an unsaturated resin having an ethylenic double bond in the molecule as a binder component and curing with radiation such as an electron beam have been developed. Proposed. As this radiation-curable resin, many resins are used that have a backbone of polyester resin, polyurethane resin, epoxy resin, etc., and have ethylenic double bonds that can be polymerized by radiation. , gamma rays, and X-rays. Many characteristics of these resins and curing methods are listed in known literature, but for example, when used as magnetic paints, they have excellent storage stability, so there is almost no waste during use, and they are easy to handle before and after forming a coating. Easy. Since the amount of solvent in the coating material is unnecessary or small, the base film is not damaged, and it is preferable from the viewpoint of environmental protection. Because it polymerizes and cures instantly with very short irradiation and leaves no unreacted low molecular weight components, the magnetic layer is hardly damaged in the post-curing process. Similarly, thermal deformation, deterioration, etc. of the base film can also be prevented. Since curing occurs through crosslinking, it is advantageous in terms of heat resistance and abrasion resistance, and it is also easy to impart flexibility. In particular, compared to conventional products, it requires almost no thermal energy for heating, and can be manufactured in large quantities in a short period of time, which is very advantageous in terms of cost. However, the currently proposed radiation-curable magnetic paints cannot be said to fully utilize the above-mentioned excellent characteristics, and furthermore, the dispersibility of magnetic powder is significantly inferior to conventional products. The current situation is that there are many. The purpose of the present invention is to modify the unsaturated polyurethane resin itself as a binder to provide a cured product that has extremely excellent dispersibility of magnetic powder and also has excellent heat resistance, hydrolysis resistance, and abrasion resistance. Our goal is to provide magnetic paints that can. The present invention contains an unsaturated polyurethane resin having two or more terminal groups having a polymerizable ethylenic double bond, which contains a modified epoxy resin in which an epoxy group is ring-opened with an amine, and a magnetic powder. This invention relates to a magnetic paint characterized by: In the present invention, by using the above specific unsaturated polyurethane resin, the dispersibility of the magnetic powder can be significantly improved due to the effect of the presence of a large number of OH groups and the synergistic effect with the presence of the bisphenol skeleton of the epoxy resin. At the same time, significant improvements have been achieved in heat resistance, hydrolysis resistance, abrasion resistance, etc. The unsaturated polyurethane resin of the present invention can be produced in various ways using, for example, a polyol (A), an organic polyisocyanate (B), an epoxy resin (C), an amine (D), and an ethylenically unsaturated compound having active hydrogen (E). It can be obtained by the following method. As the polyol (A), various polyester polyols, polyether polyols, and other polyols can be used. Examples of polyester polyols include aliphatic dicarboxylic acids having 4 to 20 carbon atoms such as adipic acid, superric acid, sebacic acid, and brassylic acid, terephthalic acid, and isophthalic acid as acid components, and ethylene glycol, propylene glycol, neopentyl glycol, Polyester polyols whose polyol components include aliphatic diols having 1 to 6 carbon atoms such as hexamethylene glycol, ether glycols such as diethylene glycol and dipropylene glycol, spiroglycols, and N-alkyl dialkanolamines such as N-methyldiethanolamine; Polycaprolactone polyol etc. can be used,
Specific examples include polyethylene adipate polyol, polybutylene adipate polyol,
Adipate polyols such as polyethylene propylene adipate polyol, terephthalic acid polyols (e.g., Toyobo Co., Ltd., product name Vylon)
RUX, Byron RV-200L), polycaprolactone polyols (eg, Daicel Chemical, trade names Plaxel 212, Plaxel 220), and the like. Specific examples of polyether polyols include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, and the like. In addition, other polyols include polycarbonate polyol (e.g., Bayer AG, West Germany, product name Desmofene 2020E), polybutadiene polyol (e.g., Nippon Soda, product name G-1000, G-
2000, G-3000, Idemitsu Petrochemical, product name Poly bd
R-45 HT), polypentadiene polyol, castor oil polyol, and the like. These polyols can be used alone or in combination of two or more. Organic polyisocyanate (B) used in the present invention
Examples include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), isophorone diisocyanate ( IPDI),
These include diisocyanates such as hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), and lysine diisocyanate (LDI), and polyisocyanates such as triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate (PAPI), and carbodiimide-modified MDI. can be used alone or in combination of two or more. A preferred example of the epoxy resin (C) used in the present invention is an epoxy resin containing one or more epoxy groups in one molecule and having an epoxy equivalent of 100 to 4,000, preferably 120 to 1,000, and more preferably an epoxy resin with a molecular weight of 100 to 4,000, preferably 120 to 1,000. It is an epoxy resin that has an epoxy group at each end and no epoxy group in the molecular chain. Examples of such epoxy resins include condensates of phenolic compounds and epichlorohydrin or methylepichlorohydrin. Examples of the phenolic compound in this case include 2,2'-bis(4,4'-hydroxyphenyl)propane (commonly known as bisphenol A), halogenated bisphenol A, 2,2'-
Examples include bis(4,4'-hydroxyphenyl)methane (commonly known as bisphenol F), resorcinol, tetrahydroxyphenylethane, novolac type polyfunctional phenols condensed from phenol or cresol and formalin, phenol and cresol. . In addition, mono- or diglycidyl ethers of alcohols such as butyl alcohol, polyethylene glycol or polypropylene glycol, 1,2,3-tris(2,3-epoxypropoxy)propane, glycidyl ethers of aniline derivatives, vinylcyclohexene dioxide, etc. alicyclic epoxides,
Examples include glycidyl esters such as phthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, and tetrahydrophthalic acid diglycidyl ester. Among these, bisphenol-based epoxy resins are particularly preferred, and epoxy resins having the following general formula are most preferred. In the formula, R ¹ and R ² are hydrogen or a methyl group, X is hydrogen or a methyl group, Cl, Br or I, and n represent a number of 0.1 or more, and n is preferably a number of 1 or more. The amines (D) are preferably compounds containing secondary amino groups, such as dialkylamines such as diethylamine, dipropylamine, and dibutylamine, N-methylethanolamine, N-butylethanolamine, diethanolamine, dipropanolamine, etc. These alkanolamines can be used alone or in combination of two or more. In the present invention, various types of ethylenically unsaturated compounds (E) having active hydrogen can be used, but representative examples include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, Mono(meth)acrylates of dihydric alcohols such as 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; mono(meth)acrylates of trihydric alcohols such as trimethylolethane, trimethylolpropane, and glycerin; ) acrylates, di- and tri(meth)acrylates of tetrahydric or higher alcohols such as pentaerythritol, etc., and these can be used alone or in combination of two or more. In the synthesis of the unsaturated polyurethane resin of the present invention, it is optional to use a chain extender (F) in addition to the above-mentioned components, and such chain extenders include, for example, 2- to 6-functional chain extenders with a molecular weight of 500 or less. Examples include polyols having a molecular weight of 500 or less and diamines having a primary or secondary terminal amino group. Suitable chain extenders include (a) ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, hexanediol,
Polyols such as glycerin, trimethylolpropane, pentaerythritol, sorbitol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (b) Hydrazine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 1,
Diamines such as 4-cyclohexanediamine (c) Alkanolamines such as ethanolamine, diethanolamine, and triethanolamine (d) Hydroquinone, pyrogallol, 4,4'-isopropylidene diphenol, aniline, and the above polyols and diamines and polyols with a molecular weight of 500 or less obtained by adding propylene oxide and/or ethylene oxide to alkanolamines in any order. The unsaturated polyurethane resin of the present invention can be synthesized by various methods using the above components, but the amines used to open the epoxy group generally have high reactivity with the NCO group of the organic polyisocyanate.
The presence of an NCO group is not preferred because ring opening of the epoxy group is likely to be inhibited. Therefore, the ring-opening reaction of the epoxy group with amines can be carried out alone, during the urethanization reaction, or when all the NCO groups have been consumed after the completion of the reaction.
A stepwise synthesis method in which the epoxy ring-opening reaction and the urethanization reaction are separated is desirable. Furthermore, when using an epoxy resin that does not have active hydrogen, it is appropriate to first perform a ring-opening reaction to generate OH groups, and then proceed to the urethanization reaction. A specific example of a synthesis method that takes these limitations into consideration is:
Compound (A), compound (B), and if necessary, compound (F) are reacted to synthesize a prepolymer with terminal NCO, and then compound (E) is reacted to synthesize a prepolymer with terminal NCO, and a prepolymer with terminal NCO is synthesized. A method of reacting ring-opened compound (C) with compound (D) and the above prepolymer,
A method for synthesizing an unsaturated polyurethane resin by reacting compounds (A), (C), (E) and optionally compound (F) with compound (B), and carrying out a ring-opening reaction with compound (D). A) and
(B), synthesize terminal NCO prepolymers from compounds (B) and (E), and add reactants of compounds (C) and (D) and optional compounds to the mixture of these two types of prepolymers. A method for reacting (F) can be exemplified. In addition, when the reaction product of the compounds (C) and (D) of the present invention has three or more active hydrogens in the molecule, it is desirable to adopt a synthesis method that takes into consideration prevention of gelation during synthesis. In the epoxy ring-opening reaction of the present invention, it is preferable to ring-open all of the epoxy groups, but of course a portion of the epoxy groups may remain.Usually, the amines are added in an amount of about 1 or less equivalents to the epoxy groups. It is preferable to use about 0.2 to 1 equivalent. The reaction is usually carried out at about 20 to 180°C, preferably about 100 to 150°C, but if the reaction mixture contains a compound or group having an ethylenic double bond,
In order to prevent thermal polymerization of these compounds or groups, it is appropriate to consider the reaction temperature and addition of a thermal polymerization inhibitor. When synthesizing the unsaturated polyurethane resin of the present invention, the ratio of each component can be appropriately determined from a wide range depending on the intended use of the resin, but usually the chemical equivalent ratio of NCO groups to active hydrogen (NCO Index)
is about 0.9 to 1.4, preferably about 0.95 to 1.2, excluding active hydrogen generated by ring opening of the epoxy group.
It is best to carry out the reaction in a range where
℃, preferably about 40 to 120℃. Since the unsaturated polyurethane resin of the present invention contains the ring-opened modified epoxy resin as a component, it has a large number of OH groups in the molecule, and the dispersibility of the magnetic powder is extremely good. The number of OH groups is usually 3
It is preferable that the number of OH groups is 6 to 30, particularly preferably 10 to 20. The OH group concentration in unsaturated polyurethane resin is 0.05meq/g
The above is preferable; if this is not the case, the dispersibility of the magnetic powder will be insufficient. Various types of magnetic powder can be used in the present invention, including iron, chromium, nickel, cobalt, alloys thereof, oxides thereof, and modified products thereof. Specific examples of oxides include γ-
Fe ₂ O ₃ , ferrite, magnetite, CrO ₂ etc. are modified with cobalt-doped γ-Fe ₂ O ₃ , cobalt-doped Fe ₂ O ₃ and the like.
Examples include a bertholide compound of Fe ₃ O ₄ . The amount of magnetic powder blended is preferably about 50 to 2000 ωt parts per 100 ωt parts of the unsaturated polyurethane resin. In the present invention, the unsaturated polyurethane resin can be synthesized without a solvent, in the presence of an organic solvent, or in the presence of an ethylenically unsaturated compound used as a crosslinking agent, which will be described later. Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and methyl propionate, ethers such as dioxane and cellosolve acetate, and dimethylformamide and dimethyl sulfoxide. In the present invention, other compounds can be mixed within a range that does not impair the purpose. Specific examples of these compounds include unsaturated polyester resins, saturated polyester resins, epoxy resins, and (meth)
Esters such as acrylic acid, polyurethane resins,
diallyl phthalate resin, ketone resin, alkyd resin, phenolic resin, rosin-modified phenolic resin, rosin ester, maleic acid-modified rosin ester, urea resin, melamine resin, polyamide resin, styrene-(meth)acrylic acid copolymer or its ester, Styrene-maleic anhydride resin or its ester, poly(meth)acrylate, petroleum resin having 5 to 9 carbon atoms, hydrogenated petroleum resin,
Examples include polybutadiene, natural or synthetic rubber, polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, polyvinyl alcohol, and wax. Further, these known compounds can be added before or during the reaction as long as they do not interfere with the synthesis of the unsaturated polyurethane resin of the present invention. In the present invention, an ethylenically unsaturated compound can be used as a crosslinking agent if necessary when curing the unsaturated polyurethane resin. Various known compounds can be used as ethylenically unsaturated compounds, but typical examples include styrene,
Vinyltoluene, chlorostyrene, t-butylstyrene, α-methylstyrene, divinylbenzene, acrylic acid, methacrylic acid, methyl, ethyl, isopropyl, n-butyl, t-butyl, α-ethylhexyl, n -Nonyl, n-decyl, lauryl, stearyl ester, etc., n-butoxyethyl acrylic acid or methacrylic acid, cyclohexyl, phenoxyethyl, tetrahydrofurfuryl, glycidyl, allyl, benzyl, tribromophenyl,
2,3-dichloropropyl, 3-chloro-2-hydroxypropyl, N,N-dimethylaminoethyl, N,N-diethylaminoethyl, Nt-butylaminoethyl ester, etc., ethylene glycol mono(meth)acrylate, propylene Glycol mono(meth)acrylate, diethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate with molecular weight (hereinafter referred to as MW) 200-1000, MW200-
1000 polyethylene glycol monomethyl ether mono(meth)acrylate, MW200~1000 polypropylene glycol mono(meth)acrylate, MW200~1000 polypropylene glycol monomethyl ether mono(meth)acrylate, MW200~1000 polyethylene glycol monoethyl ether mono(meth)acrylate ) acrylate,
MW200-1000 polypropylene glycol monoethyl ether mono(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3
-propanediol di(meth)acrylate,
1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, glycerin di(meth)acrylate, glycerin tri(meth)acrylate,
trimethylolethane di(meth)acrylate,
Trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide,
Examples include ethylene bisacrylamide, diallyl phthalate, triallyl isocyanurate, dibutyl fumarate, and vinyl acetate. However, if present during the urethanization reaction, ethylenically unsaturated compounds having active hydrogen should be excluded from the above. In the present invention, the weight ratio of the unsaturated polyurethane resin to the ethylenically unsaturated compound is preferably 30:70 to 95:5, more preferably 50:50 to 80:20. A known thermal polymerization inhibitor may be added for the purpose of stably storing the magnetic paint of the present invention. For example, hydroquinone, mono-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, hydroquinone monomethyl ether, catechol, p-tert-butylcatechol,
Examples include benzoquinone, 2,5-di-tert-butylbenzoquinone, 2,5-diphenyl-p-benzoquinone, 2,6-di-tert-butyl-p-cresol, and picric acid. It is desirable that these thermal polymerization inhibitors prevent only the thermal polymerization reaction (dark reaction) without inhibiting the photocuring reaction, so the amount added should be adjusted based on the total amount of the unsaturated polyurethane resin and crosslinking agent. It is desirable that the amount ranges from 0.001 to 2.5% by weight, preferably from 0.005 to 1% by weight. Furthermore, in the present invention, commonly used additives such as dispersants, lubricants, abrasives, and antistatic agents can be added as necessary. The magnetic coating composition of the present invention can be obtained by mixing the above-mentioned components by various known methods, and for example, a mixer, roll mill, ball mill, sand mill, high-speed impeller, etc. can be used. The magnetic paint of the present invention can be applied to tapes, sheets, cards,
It is applied to various types of supports such as disks and drums. The support usually has a thickness of about 5 to 50μ,
It is preferably about 10 to 40μ, and suitable materials include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose acetate, polycarbonate, polyamide, polyimide, polyamideimide, and the like. Various methods can be used to apply the magnetic coating onto the support, such as impregnation coating, air doctor coating, air knife coating, blade coating, reverse roll coating, gravure coating, cast coating, and spray coating. After coating, the magnetic powder may be subjected to treatment to orient it if necessary, or dried if it contains a general organic solvent. The drying temperature is usually approx.
The temperature is about 20 to 120°C, preferably about 50 to 100°C, and the drying time is about 30 seconds to 10 minutes, preferably about 1 to 5 minutes. Furthermore, if necessary, a surface smoothing treatment can be performed before or after curing, or the material can be cut into a desired shape. The magnetic paint of the present invention can be cured by a known method. For example, when curing with an electron beam, the acceleration voltage is 100 to 1000 KeV, preferably 150 to 1000 KeV.
A cured product can be obtained by irradiating in an inert gas atmosphere using a 300 KeV electron beam irradiation device such that the total absorbed dose is 0.5 to 20 Mrad, preferably 2 to 15 Mrad. In addition, in the present invention, other curing means such as those using thermal energy such as infrared rays, high frequency waves, or microwaves, that is, heating curing methods, curing methods using ultraviolet rays obtained from mercury lamps, xenon lamps, etc., or
A method of curing by irradiating with other radiation such as rays or gamma rays can also be used. In the present invention, when using high-energy ionizing radiation such as electron beams, X-rays, and γ-rays, which have the effect of being absorbed by substances and emitting secondary electrons, it is not necessary to add a polymerization initiator. is also good, but
When curing by heating or ultraviolet rays, it is preferable to add a thermal polymerization initiator or a photopolymerization initiator. Examples of these thermal or photopolymerization initiators include ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, hydroperoxides such as cumene hydroperoxide and tert-butyl peroxide, and di-tert-butyl peroxide. Examples include dialkyl peroxides such as oxide and dicumyl peroxide, peroxy esters such as tert-butyl peroxylaurate and tert-butyl peroxybenzoate, and azo compounds such as azobisisobutyronitrile.
Further, polymerization accelerators such as metal soaps such as cobalt and manganese for the above-mentioned ketone peroxides, or reducing amines for the above-mentioned hydroperoxides can also be used. As described above, the magnetic paint of the present invention is characterized by containing as a binder an unsaturated polyurethane resin containing as a component a modified epoxy resin in which epoxy groups are ring-opened with amines, and the unsaturated polyurethane resin has molecular Due to the presence of a large number of OH groups in the resin, the dispersibility of the magnetic powder in the resin is extremely good, and the resulting magnetic paint has excellent heat resistance, hydrolysis resistance, and abrasion resistance. This is a magnetic material for magnetic recording that has been improved and has excellent electrical properties and durability. A detailed explanation will be given below with reference to synthesis examples and examples. Note that "parts" or "%" simply means parts by weight or percent by weight. Synthesis Example 1 Epikote 1001 (molecular weight
900, epoxy equivalent 475) 225.9g, diethanolamine, 48.0g, dioxane 274.5g and hydroquinone 0.55g were added, heated to 108.5°C, and reacted for about 3 hours under reflux of dioxane to open the epoxy group. A modified epoxy resin solution (A) was obtained. Synthesis Example 2 Put TDI (75.0g) into a reactor equipped with a stirring device,
Warmed to 80℃, Byron RV200L (molecular weight 1940)
Gradually drop a mixed solution of 418.1 g, dioxane 493.35 g, and dibutyltin dilaurate 0.25 g,
The mixture was heated to ℃ and allowed to react for about 3 hours. The above reactants were placed in a separately prepared reactor equipped with a stirring device.
Add 971.3 g of the mixture and warm to 80°C, and gradually dropwise add a mixed solution of 22.15 g of 2-hydroxyethyl acrylate (ethylene glycol monoacrylate, hereinafter abbreviated as HEA), 1.0 g of hydroquinone, and 22.25 g of dioxane, for about 3 hours. The reaction was carried out to obtain urethane prepolymer (B). Synthesis Example 3 In Synthesis Example 2, polycaprolactone polyol (trade name Plaxel) was used instead of Vylon RV200L.
A urethane prepolymer (C) was obtained in the same manner as in Synthesis Example 2 except that urethane prepolymer (C) was used. Synthesis Example 4 175.0 g of the modified epoxy resin solution (A) obtained in Synthesis Example 1 was placed in a reactor equipped with a stirring device, and heated to 80°C. 250.0g and 699.0g of B) and (C) respectively
A mixed solution of g was gradually added and reacted for about 1.5 hours to obtain an unsaturated polyurethane resin solution (). This solution had a solid content of 50% and had 0.78 meq/g of OH groups in the solid content. Synthesis Example 5 In Synthesis Example 1, diethanolamine was added to 22.5
g, hydroquinone 0.5g, dioxane 248.9
Modified epoxy resin solution was prepared in the same manner except that g was
(D) was produced, and (D) was used in place of (A) in Synthesis Example 4.
Using 159.0g, an unsaturated polyurethane resin solution () was obtained by the same reaction. This solution had a solid content of 50% and contained 0.38 meq/g of OH groups in the solid content. Synthesis Example 6 In Synthesis Example 1, 234.24g of Epicote 1001,
A modified epoxy resin solution (E) was produced by the same reaction using 15.76 g of N-methylethanolamine, 250.5 g of dioxane, and 0.50 g of hydroquinone instead of diethanolamine, and the same reaction was carried out in Synthesis Example 4.
Using 125.5 g of (E) instead of (A), the same reaction was carried out to obtain an unsaturated polyurethane resin solution (). This solution had a solid content of 50%, and the OH group concentration in the solid content was 0.14 meq/g. Synthesis Example 7 Put 154.18g of IPDI into a reactor equipped with a stirring device,
465.6g of Byron RV200L in a room heated to ℃
A mixed solution of 214.5 g of Desmophene 2020E (molecular weight 2000), 1.75 g of hydroquinone, and 872.62 g of dioxane was gradually added dropwise, heated to 90°C, and added a total of 0.25 g of dibutyltin dilaurate in two portions during the process. After reacting for an hour, further HEA
A mixture of 36.30g of
I got it. Synthesis Example 8 350.4 g of the modified epoxy resin solution (A) obtained in Synthesis Example 1 was placed in a reactor equipped with a stirring device, and 682.35 g of urethane prepolymer (F) was gradually added dropwise into the heated mixture at 80°C. The mixture was reacted for about 2 hours to obtain an unsaturated polyurethane resin solution (2). The solid content of this solution was 50%, and the solid content contained 2.10 meq/g of OH groups. Synthesis Example 9 An unsaturated polyurethane resin solution () was obtained in the same manner as in Synthesis Example 8, except that 88.1g of the same (D) obtained in Synthesis Example 5 was used instead of the modified epoxy resin solution (A). . This solution had a solid content of 50%, and the OH group concentration in the solid content was 0.24 meq/g. Synthesis Example 10 An unsaturated polyurethane resin was prepared in the same manner as in Synthesis Example 1, except that 144.4 g of the epoxy resin solution (G) from which diethanolamine was removed was used in place of the modified epoxy resin solution (A) in Synthesis Example 4. A solution () was obtained. Synthesis Example 11 In the same manner as in Synthesis Example 8, except that 99.2g of epoxy resin solution (G) was used instead of modified epoxy resin solution (A), unsaturated polyurethane resin solution () was prepared.
I got it. Synthesis Example 12 In the same manner as in Synthesis Example 4 except that 30.3 g of a 50% dioxane solution of glycerin was used instead of the modified epoxy resin solution (A), the OH group concentration was 0.68 meq/g.
An unsaturated polyurethane resin solution () was obtained. Synthesis Example 13 In the same manner as in Synthesis Example 4, except that 8.48 g of diethylene glycol was used instead of the modified epoxy resin solution (A), an unsaturated polyurethane resin solution (A) was prepared.
I got it. Examples 1 to 6 and Comparative Examples 1 to 6 The unsaturated polyurethane resin solutions obtained in the above synthesis examples were mixed with the compositions shown in Tables 1 and 2, and kneaded in a ball mill for 24 hours to obtain magnetic properties. Got the paint. Each of the obtained magnetic paints was applied onto a polyester film using a doctor blade, dried in an oven at 80°C for 3 minutes, and then exposed to an accelerating voltage using a curtain beam type electron beam irradiation device.
The coating film was cured by irradiation at 150 KeV and a beam current of 10 mA to give an irradiation dose of 5 Mrad. After curing, the surface gloss of the magnetic coating film was measured using a gloss meter (Toyo Seiki S-60) in order to examine the dispersibility of the magnetic powder. The better the dispersibility, the better the gloss. In addition, in order to examine the durability of the magnetic coating, the coating was placed in a constant temperature and humidity chamber adjusted to 70℃ and 95% RH for 400 hours, and after humidification and heating, the surface gloss was measured again. I saw the change. Furthermore, a scratch test was conducted using a 2H hardness pencil (Mitsubishi Uni) to examine the strength of the coating film. The evaluation criteria are
〇: No scratches, △: Scratches, ×: Peels off. Note that both samples before humidification and heating were rated ○. The results are summarized in a table. In the table, PU is an unsaturated polyurethane resin solution, HEMA is 2-hydroxyethyl methacrylate, THF-A is tetrahydrofurfuryl acrylate, SA is an ester of HEMA and succinic acid, and 2-methacryloxyethyl succinate.
PA is an ester of HEMA and phosphoric acid, a mixture of 2-methacryloxyethyl phosphate and di(2-methacryloxyethyl) phosphate, MEK is methyl ethyl ketone, and the number of PUs represents the number of solids in the solution.

【table】

【table】

[Table] Synthesis Example 14 142.4 g of the modified epoxy resin solution (A) obtained in Synthesis Example 1 and 3.1 g of 1,4-butanediol were placed in a reactor equipped with a stirring device, heated to 80°C, and Synthesis Example 2
and urethane prepolymer (B) obtained in Synthesis Example 3
A mixed solution of 721.2 g and 334.0 g of (C), respectively, was gradually added and reacted for about 1.5 hours to obtain an unsaturated polyurethane resin solution (). This solution has a solid content of 50% and contains 0.59meq/OH group in the solid content.
It had g. Synthesis Example 15 In Synthesis Example 6, N-methylethanolamine
A modified epoxy resin solution (H) was produced in the same manner except that 10.7 g was used, and in place of (A) in Synthesis Example 4,
An unsaturated polyurethane resin solution (XI) was obtained by the same reaction using 125.9 g of (H). This solution has a solid content of 50%, and the OH group concentration in the solid content is
It was 0.09meq/g. Synthesis Example 16 An unsaturated polyurethane resin solution was prepared in the same manner as in Synthesis Example 1 except that 116.6 g of the epoxy resin (G) from which diethanolamine was removed was used in place of the modified epoxy resin solution (A) in Synthesis Example 14. (XII) was obtained. Examples 7 to 11 and Comparative Examples 7 to 9 Using the unsaturated polyurethane resins obtained in Synthesis Examples 14 to 16, the compositions shown in Table 3 were mixed and kneaded in a ball mill for 40 hours to obtain magnetic paints. Ta. Using the obtained paint, in the same manner as in Example 1,
The surface gloss of the coating film was measured. In addition, an adhesion test and powder falling amount were measured by the following method. In the adhesion test, cellophane tape was adhered to the magnetic coating under a load of 5 kg and then suddenly peeled off, and the degree of peeling was evaluated on a three-grade scale. 〇: Peeling area 0% △: 〃 0 to 25% ×: 〃 25% or more
The weight loss (mg) was measured when the magnetic coating was moved back and forth 100 times. In the table, HPMA is hydroxypropyl methacrylate, and magnetic powder A has a specific surface area of 48 m ² /g.
Fe--Co alloy, B is 32 m ² /g of Co-coated γ-
Fe ₂ O ₃ and C indicate γ-Fe ₂ O ₃ of 22 m ² /g.

Claims (1)

[Scope of Claims] 1. An unsaturated polyurethane resin having two or more unterminated groups having a polymerizable ethylenic double bond, the component being a modified epoxy resin in which an epoxy group is ring-opened with an amine; and a magnetic paint characterized by containing magnetic powder. 2. The magnetic paint according to claim 1, wherein the unsaturated polyurethane resin has 0.05 meq/g or more of OH groups in its molecular chain. 3 Epoxy resin has a general formula (R ¹ , R ² are hydrogen or a methyl group, X is hydrogen or a methyl group, Cl, Br or I, n are numbers of 0.1 or more) paint.