JPH06274849A - Vinyl chloride base binder resin composition for magnetic recording medium and magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve electromagnetic characteristics, heat resistance, wear resistance and durability by filling magnetic powder into a vinyl chloride base binder resin compsn. for a magnetic recording medium at high density under high orientation. CONSTITUTION:A copolymer used contains at least one of a vinyl monomer contg. an epoxy group and a vinyl monomer contg. a hydroxyl group such as glycidyl methacrylate and allyl glycidyl ether. The vinyl monomer content of the copolymer is regulated to 0.05-30wt.% because dehydrochlorination inhibiting effect is reduced in the case of a lower content and the durability of a magnetic coating film is deteriorated owing to a reduced amt. of vinyl chloride in the case of a higher content. Another example of a copolymer used contains a vinyl monomer contg. hydrogen, NH4<+> or an alkali metal or a vinyl monomer contg. hydrogen, an alkali metal or a hydrocarbon group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride-based binder resin composition for a magnetic recording medium and a magnetic recording medium using the same.

[0002]

2. Description of the Related Art A coating type magnetic recording medium such as a magnetic tape or a magnetic card is generally manufactured by coating a polyester film with a magnetic coating material containing a magnetic powder and a binder resin to form a magnetic layer. The quality required for this magnetic recording medium includes electromagnetic conversion characteristics obtained by filling magnetic powder with high density and high orientation, and durability that can withstand friction with a magnetic head and the like. To be

Therefore, in the binder resin used in the magnetic recording medium, magnetic powder is highly dispersed in the magnetic paint to give the magnetic coating film excellent electromagnetic conversion characteristics, and at the same time, it is combined with a crosslinking agent such as an isocyanate compound. By doing so, strength is given to the magnetic coating film. Further, in order to maintain the quality of the magnetic recording medium and the magnetic characteristics for a long time, it is necessary that the magnetic powder in the magnetic coating film is not deteriorated.

In recent years, with the development of AV equipment and the like, high quality is required for magnetic recording media, and magnetic powder particles are more and more required for filling magnetic powder with higher density in a magnetic coating film. It tends to be atomized. Therefore, there has been a demand for a binder resin having more excellent dispersibility than ever.

Conventionally, as a vinyl chloride binder resin having excellent dispersibility, a vinyl chloride copolymer containing a functional group having high hydrophilicity and a hydroxyl group capable of undergoing a cross-linking reaction with an isocyanate compound or the like in order to obtain an affinity with the magnetic powder. Polymers are commonly used. Particularly, as the hydrophilic functional group having a strong affinity with the magnetic powder, for example, —COOH, —SO ₃
Na, -PO (OH) _2, etc. [Japan Adhesion Association Magazine 17, 1
55 (1981)] has been reported and Japanese Patent Publication No. 1-26.
JP-A-625 discloses, as a vinyl chloride-based binder resin having high dispersibility and excellent reactivity with a crosslinking agent, an unsaturated monomer having a strong acid group containing vinyl chloride, sulfur or phosphorus, and -X. A vinyl chloride-based copolymer comprising an -OH group (X is an organic residue) is disclosed.

[0006] Japanese Patent Publication No. 3-97764 discloses that
In order to obtain similar performance, a vinyl chloride-based binder resin containing a sulfonic acid group, a carboxyl group, and a phosphoric acid group is disclosed, and Japanese Patent Publication No. 1-26627 discloses that an epoxy group-containing monomer contains a strong acid. A resin for a magnetic coating in which an alkali metal salt is copolymerized with vinyl chloride is disclosed.

However, when the amount of hydroxyl groups in the binder resin is increased, the crosslinkability with the isocyanate compound is improved and the abrasion resistance of the magnetic coating film is improved, but the mutual interaction between hydroxyl groups or between hydroxyl groups and other functional groups. There is a problem that the viscosity of the magnetic coating increases due to the action, and the dispersibility decreases, and when the amount of hydroxyl groups decreases, the dispersibility improves, but the crosslinking density decreases and the durability of the magnetic coating decreases. There was a point. Therefore, the resin must be designed and manufactured according to the required quality, a variety of products are required, and it is difficult to obtain a binder resin having the required performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to have an excellent affinity with magnetic powder and to be able to fill the magnetic powder with high density and high orientation, A vinyl chloride-based binder resin composition for magnetic recording which can be easily manufactured to meet these required qualities, and a magnetic recording having a magnetic coating film excellent in electromagnetic characteristics, heat resistance, durability and abrasion resistance. To provide the medium.

[0008]

The copolymer (I) used in the present invention comprises at least one of a vinyl monomer having an epoxy group and a vinyl monomer having a hydroxyl group.
It consists of a seed vinyl monomer and a vinyl chloride monomer.

Examples of the vinyl monomer having an epoxy group include glycidyl methacrylate and allyl glycidyl ether.

In the copolymer (I), when the content of the vinyl monomer having an epoxy group is small, the effect of suppressing dehydrochlorination from vinyl chloride is lowered, and when the content is large, the vinyl chloride component is reduced and the magnetic coating is reduced. Since the durability of the film decreases, the content of the vinyl monomer is 0.05 to 30% by weight.
Is preferable, and more preferably 1 to 16% by weight.

Examples of the vinyl monomer having a hydroxyl group include a reaction product of (meth) acrylic acid and a polyhydric alcohol, a (meth) acrylic acid amide, and the like.

Examples of the reaction product of the (meth) acrylic acid and the polyhydric alcohol include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 3 - chloro-2-hydroxypropyl (meth) acrylate, CH ₂ = CR ¹ -COO- [CH ₂
CH (CH ₃ ) -O] ₁ -H (R ¹ is hydrogen or a methyl group,
1 represents an integer of 2 to 6) polypropylene glycol mono (meth) acrylate represented by CH ₂ ═CR ² —
_{COO- (CH 2 CH 2 O)} m -H (R 2 is hydrogen or a methyl group, m is an integer of 2-9) polyethylene glycol mono (meth) acrylate represented by 2-hydroxyethyl-2 ' -Acryloyloxyphthalate, C
^{_{H 2 = C (R 3)}} -COOCH 2 CH 2 -O- (CO-C
₅ H ₁₀ O) _n —H (R ³ is hydrogen or a methyl group, n is 1 to
A lactone (meth) acrylate represented by (denoting an integer of 5).

Examples of the (meth) acrylic acid amide include N-methylol (meth) acrylamide.

In the above copolymer (I), when the content of the vinyl monomer containing a hydroxyl group becomes small, the reactivity with isocyanate becomes insufficient and durability deteriorates. Since the viscosity of the magnetic coating material increases due to the interaction of 1 to 50% by weight,
It is more preferably 3 to 20% by weight.

The copolymer (II) used in the present invention is S
Vinyl monomer containing O ₃ M ¹ group (M ¹ represents hydrogen, NH ₄ ⁺ or alkali metal), PO ₂ (OM ² ) ₂ group (M ² represents hydrogen, alkali metal or hydrocarbon group)
At least selected from the group consisting of vinyl monomers containing a vinyl monomer containing a tertiary amine group, vinyl monomers containing a quaternary ammonium salt group, vinyl monomers containing a carboxyl group and vinyl monomers containing a hydroxyl group. A vinyl monomer containing one or more functional groups, a vinyl monomer containing an epoxy group,
It consists of vinyl chloride monomer.

Examples of the above-mentioned SO ₃ M ¹ group-containing vinyl monomers include sodium ethylene sulfonate, potassium ethylene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid soda, and 2-acrylamido-
Examples thereof include ammonium 2-methyl propane sulfonate, sodium ethyl sulfonate methacrylate, allyl sulfonic acid, methacryl sulfonic acid, and styrene sulfonic acid.

Examples of the vinyl monomer having a PO ₂ (OM ² ) ₂ group include acid phosphoxyethyl.
(Meth) acrylate, acid phosphoroxypropyl (meth) acrylate, 3-chloro-2-acid phosphoroxypropyl (meth) acrylate, methacryloyloxyethyl acid phosphate monoethanolamine half salt and the like can be mentioned.

Examples of the vinyl monomer containing a tertiary amine group include dimethylaminopropyl methacrylamide, N, N-dimethylaminopropyl acrylamide and the like.

As the vinyl monomer containing the quaternary ammonium salt group, for example, 2-hydroxy-3-
Methacryloyloxypropyl trimethylammonium chloride, methacryloyloxyethyl trimethylammonium chloride, trimethyl-3-methacrylamido-propylammonium chloride and the like can be mentioned.

Examples of the vinyl monomer containing a carboxyl group include (meth) acrylic acid, succinic acid mono (meth) acryloyloxyethyl ester, phthalic acid mono (meth) acryloyloxyethyl ester,
Examples thereof include one having one carboxyl group in a molecule such as succinic acid monomethacryloyloxyethyl ester, and one having a plurality of carboxyl groups in a molecule such as maleic acid and fumaric acid.

Examples of the vinyl monomer containing a hydroxyl group include the same vinyl monomers containing a hydroxyl group used in the copolymer (I).

In the copolymer (II), when the content of the vinyl monomer having a functional group is small, the affinity between the magnetic powder and the binder resin becomes insufficient and it is difficult to highly disperse the magnetic powder. When the amount of the vinyl monomer increases, the viscosity of the magnetic coating material increases and the dispersibility of the magnetic powder decreases due to the interaction of the functional groups. Therefore, the content of the vinyl monomer is preferably 0.1 to 40% by weight, more preferably 1 ~ 25% by weight.

Further, in the above copolymer (II), when the vinyl monomer containing a hydroxyl group is used in a large amount, the solvent solubility decreases, and the interaction of the hydroxyl groups increases the viscosity of the magnetic paint. . Further, when it is used together with the copolymer (I), it may be small because the copolymer (I) has a hydroxyl group. Since the compound (III) does not have a hydroxyl group, a large amount is required, and the content of the vinyl monomer containing a hydroxyl group is preferably 40% by weight or less, more preferably 15% by weight or less.

The epoxy group-containing vinyl monomer may be the same as the epoxy group-containing vinyl monomer used in the copolymer (I).

In the above copolymer (II), when the content of the vinyl monomer having an epoxy group is small, the effect of suppressing dehydrochlorination from vinyl chloride decreases, and when the content is large, the vinyl chloride component is relatively contained. The content of the vinyl monomer is 0.5 to 30% by weight because the amount of the vinyl monomer decreases and the durability of the magnetic coating film decreases.
Is preferable, and more preferably 1 to 16% by weight.

The above-mentioned copolymer (III) is a SO ₃ M ³ group (M
^At least one selected from the group consisting of a vinyl monomer containing hydrogen, NH ₄ ⁺ or an alkali metal), a vinyl monomer containing a tertiary amine group and a vinyl monomer containing a quaternary ammonium salt group. It is composed of a vinyl monomer containing the above functional group and a vinyl chloride monomer.

As the vinyl monomer containing the SO ₃ M ³ group, the SO ₃ M used in the copolymer (II) is used.
^The same as the vinyl monomer containing ^one group can be mentioned.

Examples of the vinyl monomer containing a tertiary amine group and the vinyl monomer containing a quaternary ammonium salt group are the same as those used in the copolymer (II).

In the copolymer (III), when the content of the vinyl monomer having a functional group is small, the affinity between the magnetic powder and the binder resin becomes insufficient, so that it becomes difficult to highly disperse the magnetic powder. When the amount is large, the viscosity of the magnetic coating material increases due to the interaction between the functional groups and the dispersibility of the magnetic powder decreases, so the vinyl monomer containing the functional group is preferably 0.1 to 40% by weight, more preferably 1 ~ 9
% By weight.

If the degree of polymerization of the above-mentioned copolymers (I), (II) and (III) becomes small, the mechanical strength of the magnetic coating film will decrease, and if it becomes high, the viscosity will increase and the solvent solubility will decrease. 100 to 900 is preferable, and 1 is more preferable.
It is 50 to 600.

If desired, the above-mentioned copolymers (I), (II) and (III) may be copolymerized with a monomer having a copolymerizable unsaturated group.

Examples of such a monomer include α-olefins such as ethylene, propylene and 1-hexene; vinyl esters such as vinyl acetate and vinyl propionate; butyl vinyl ether, cetyl vinyl ether,
Vinyl ethers such as phenyl vinyl ether; aromatic vinyls such as styrene and α-methylstyrene; (meth)
Vinyl cyanides such as acrylonitrile; vinyl halides such as vinylidene chloride and vinyl fluoride; unsaturated dicarboxylic acid esters such as dimethyl maleate and dimethyl fumarate; unsaturated dicarboxylic acid anhydrides such as maleic anhydride; N -N-substituted maleimides such as phenylmaleimide and N-cyclohexylmaleimide; Formula CH ₂ typified by methyl methacrylate, n-butyl acrylate, etc.
_{^{= CR 4 -COO- (CH 2)}} p -CH 3 (R is a hydrogen or a methyl group, p is an integer of 0) alkyl (meth) acrylates represented by, 1,7,7-trimethyl Bicyclo [2.2.1] hept-2-yl acrylate etc. are mentioned.

In particular, in order to improve the solvent solubility of the copolymer and reduce the viscosity, n-butyl acrylate, 1,7,
7-Trimethylbicyclo [2.2.1] hept-2-yl acrylate is preferred.

In the vinyl chloride resin-based binder resin composition for magnetic recording of the present invention, the copolymer (I) or (II) is used.
When the ratio of is decreased, the effect of suppressing dehydrochlorination from vinyl chloride is reduced and the durability of the magnetic coating film is insufficient,
When the proportion of the copolymer (II) or (III) decreases, the dispersibility of the magnetic powder decreases, so any one of the copolymers (I), (II) and (III) is more than 95% by weight. It is contained in a ratio that does not increase.

Next, the second aspect of the present invention will be described. Examples of the support used in 2 of the present invention include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulosic derivatives such as polyolefin resins, cellulose triacetate and cellulose diacetate, vinyl resins, polyimide resins, polyamide resins. A film or sheet, such as aluminum;
Non-magnetic metal foil such as copper; paper, ceramic sheet and the like.

In the magnetic recording medium of the present invention 2, a magnetic layer is formed on one surface of the support and a non-magnetic layer is formed on the other surface, and the magnetic layer is composed of magnetic powder and a binder resin composition.
The nonmagnetic layer is composed of a binder resin composition. At least one of the binder resin compositions uses the vinyl chloride-based binder resin composition for magnetic recording of the present invention.

The magnetic layer is formed by applying magnetic powder and a magnetic paint obtained from the vinyl chloride resin-based binder resin composition for magnetic recording of the present invention and drying the non-magnetic layer of the present invention. It is formed by applying and drying a non-magnetic coating material obtained from a vinyl chloride resin-based binder resin composition for magnetic recording.

The magnetic coating material is produced from a vinyl chloride resin-based binder resin composition for magnetic recording, magnetic powder and a solvent.

The magnetic powder may be, for example, γ-Fe ₂
O ₃ , Co-containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , CrO
₂ , Co-Ni-P alloy, Fe-Co-Ni alloy, Co
Known ferromagnetic powders such as ferrite, Ba ferrite, Sr ferrite, Fe alloy, Co alloy, and Ni alloy can be used.

Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate and glycol monoethyl ether acetate; glycol. Glycol ethers such as dimethyl ether and dioxane; aromatic hydrocarbons such as benzene, toluene and xylene; methylene chloride, ethylene chloride, carbon tetrachloride,
Examples thereof include chlorinated hydrocarbons such as chloroform, ethylene chlorohydrin, and dichlorobenzene, which may be used alone or in combination of several kinds.

If desired, various additives such as a curing agent, an abrasive, a lubricant, a dispersant, an antistatic agent and a stabilizer may be added to the magnetic paint.

Known curing agents such as polyisocyanate compounds are used as the curing agent, and examples of the lubricant include dialkyl polysiloxane, phenyl polysiloxane, fluoroalkyl polysiloxane (alkyl group having 1 to 5 carbon atoms). Inorganic powders such as silicone oil, molybdenum disulfide and tungsten disulfide, unsaturated aliphatic hydrocarbons and the like.

Examples of the dispersant include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and other fatty acids having 12 to 18 carbon atoms.

Examples of the antistatic agent include conductive powders such as carbon black, alkylene oxide-based compounds,
Glycerin-based nonionic surfactants; cationic surfactants such as higher alkyl amines and quaternary ammonium salts; anionic surfactants containing acidic groups such as carboxyl groups, phosphate groups, sulfone groups; amino acids, amino sulfones Examples thereof include amphoteric surfactants such as acids.

Examples of the above stabilizers include those represented by the general formula C ₁₇
H ₃₅ COOM ⁵ (wherein M ⁵ is Pb, Cd, Ba, Ca,
Zn, Mg or Al); organic tin compounds such as organic tin malate, organic tin laurate, organic tin mercapto, methyl tin, butyl tin and octyl tin.

In order to produce a magnetic paint using the above binder resin composition, the magnetic powder is kneaded and dispersed with a binder resin solution (a binder resin and polyurethane resin or polycarbonate, polyurethane resin etc. dissolved in a solvent). However, a method of pre-dispersing with a two-roll mill, a three-roll mill, an open kneader, a pressure kneader, a continuous kneader or the like, and then post-dispersing with a sand grinder, a ball mill or the like is generally used.

In order to obtain a magnetic recording medium, it is preferable to form a magnetic layer on a support and then orient the magnetic layer through an electromagnet (solenoid).

The non-magnetic paint is produced from a vinyl chloride resin-based binder resin composition for magnetic recording and a solvent.

As a method for applying the magnetic coating material and the non-magnetic coating material to the support, air doctor coating, blade coating, rod coating, extrusion coating, air knife coating,
Squeeze coat, impregnation coat, reverse roll coat,
Examples include transfer roll coat, gravure coat, kiss coat, cast coat, spray coat, spin coat and the like.

The above magnetic layers are the first magnetic layer (upper layer) and the second magnetic layer.
When it is composed of two magnetic layers (lower layers), the binder resin composition of the present invention may be used as the second magnetic layer in order to disperse the non-ferromagnetic powder.

Examples of the above non-ferromagnetic powder include carbon black, graphite, titanium oxide, barium sulfate and Zn.
S, MgCO ₃ , ZnO, CaO, γ-iron oxide, molybdenum disulfide, boron nitride, MgO, SnO ₂ , Si
O ₂ , CrO ₃ , Cr ₂ O ₃ , α-Al ₂ O ₃ , Si
C, cerium oxide, corundum, artificial diamond, α
-Iron oxide, garnet, garnet, silica, silicon nitride, silicon carbide, molybdenum carbide, tungsten carbide,
Examples include titanium carbide, tripoli, diatomaceous earth, dolomite, and the like.

The non-magnetic layer is formed in the same manner except that the magnetic powder is not added to the magnetic paint.

The above magnetic recording medium is used, for example, as a magnetic tape such as an audio cassette tape, a VTR tape, a magnetic disk such as a floppy disk, and a magnetic card.

[0054]

EXAMPLES Examples of the present invention will be described below. (1) Polymerization of Copolymer A of Vinyl Monomer Containing Sulfonic Acid Group and Vinyl Chloride Monomer [Initial Charge] Methanol (reagent 1 was added to a stainless steel autoclave with an internal volume of 18 liter equipped with a stirrer.
Class) 8000 parts by weight, 50 parts by weight of sodium ethylene sulfonate, and 35 parts by weight of t-butylperoxyneodecanoate as a polymerization initiator, and then exhausted with an aspirator for 5 minutes to remove residual air, 2300 parts by weight of vinyl chloride monomer were charged.

[Preparation of Post-Addition] After removing air from a 3 liter suspendable stainless steel container (hereinafter referred to as an addition container), 400 parts by weight of n-butyl acrylate and 1000 parts by weight of methanol were sucked and further vinyl chloride monomer was added. 1450 parts by weight were press-fitted. The addition container was shaken to sufficiently mix and dissolve the contents and hung on a spring balance, and was connected to an addition nozzle provided in the polymerization reaction container from a valve at the bottom of the container using a flexible tube.

[Polymerization reaction operation] The rotation speed of the stirrer of the polymerization reactor was set to 250 rpm, 62 parts by weight of the mixed solution was added from the addition container to the polymerization reactor, and warm water was passed through the jacket so that the internal temperature of the reactor was 53 ° C. The temperature was raised to. Inner temperature is 5
When the temperature reached 3 ° C., 62 parts by weight of the mixed solution was added from the addition container to the polymerization reaction container, and then 50 parts by weight × 3 times, 63 parts by weight × 10 times, every 5 minutes depending on the progress of the polymerization reaction. 6
0 parts by weight × 13 times, 53 parts by weight × 22 times, 48 times in total, were added in portions. Further, the internal temperature of the polymerization reactor was raised and the temperature was adjusted from the time when it reached 53 ° C., so that it was kept constant at 53 ° C. during the reaction. Five minutes after the last addition was completed, the internal temperature was cooled to 25 ° C. to stop the polymerization reaction. After cooling, the vinyl chloride monomer remaining inside the polymerization reactor was discharged, and nitrogen gas was further aerated to sufficiently remove the vinyl chloride monomer. Then, the slurry was extracted from the lower part of the polymerization reactor, filtered, and vacuum dried at 50 ° C. for 10 hours to obtain 1800 parts by weight of white powder of copolymer A. The degree of polymerization and the composition of the obtained copolymer A are shown in Table 1.

(2) Polymerization of Copolymer B of Vinyl Monomer Containing Sulfonic Acid Group and Vinyl Chloride Monomer In Example 1, instead of n-butyl acrylate 1,7,7
-Trimethylbicyclo [2.2.1] hept-2-yl acrylate 80 parts by weight and n-butyl acrylate 3
Copolymer B was obtained in the same manner as in (1) except that 100 parts by weight was used. The polymerization degree and composition of the resulting copolymer B are shown in Table 1.

(3) Polymerization of Copolymer C of Vinyl Monomer Containing Tertiary Amine Group and Vinyl Chloride Monomer [Initial Charge] Methanol (reagent was added to a stainless steel autoclave with an internal volume of 18 liter equipped with a stirrer. 1
7800 parts by weight, 30 parts by weight of t-butylperoxyneodecanoate as a polymerization initiator were charged, and the mixture was evacuated with an aspirator for 5 minutes to eliminate residual air, and then 3000 parts by weight of vinyl chloride monomer were added. I prepared it.

[Preparation of Post-Addition] After removing air from a 3 liter suspendable stainless steel container (hereinafter referred to as an addition container), 400 parts by weight of n-butyl acrylate,
20 parts by weight of N, N-dimethylaminopropylacrylamide and 1000 parts by weight of methanol were suctioned, and 1450 parts by weight of vinyl chloride monomer was further press-fitted. The addition container was shaken to sufficiently mix and dissolve the contents and hung on a spring balance, and was connected to an addition nozzle provided in the polymerization reaction container from a valve at the bottom of the container using a flexible tube.

[Polymerization reaction operation] The rotation number of the stirrer of the polymerization reactor was set to 250 rpm, 72 parts by weight of the mixed solution was added from the addition container to the polymerization reactor, and warm water was passed through the jacket to adjust the internal temperature of the reactor to 53 ° C. The temperature was raised to. Inner temperature is 5
When the temperature reached 3 ° C., 72 parts by weight of the mixed solution was added from the addition container to the polymerization reaction container, and then 50 parts by weight × 3 times, 63 parts by weight × 10 times every 5 minutes depending on the progress of the polymerization reaction. 6
0 parts by weight × 13 times, 53 parts by weight × 22 times, 48 times in total, were added in portions. Further, the internal temperature of the polymerization reactor was raised and the temperature was adjusted from the time when it reached 53 ° C., so that it was kept constant at 53 ° C. during the reaction. Five minutes after the last addition was completed, the internal temperature was cooled to 25 ° C. to stop the polymerization reaction. After cooling, the vinyl chloride monomer remaining inside the polymerization reactor was discharged, and nitrogen gas was further aerated to sufficiently remove the vinyl chloride monomer. Then, the slurry was taken out from the lower part of the polymerization reactor, filtered, and then vacuum dried at 50 ° C. for 10 hours to obtain 1800 parts by weight of a white powder of copolymer C. The degree of polymerization and the composition of the obtained copolymer C are shown in Table 1.

(4) Polymerization of Copolymer D of Vinyl Monomer Containing Quaternary Ammonium Base and Vinyl Chloride Monomer Instead of N, N-dimethylaminopropylacrylamide alone, 40 parts by weight of methacryloyloxyethyl trimethyl ammonium chloride. A copolymer D was obtained in the same manner as in (3) except that was used. The polymerization degree and composition of the obtained copolymer D are shown in Table 1.

(5) Polymerization of Copolymer E of Vinyl Monomer Containing Sulfonic Acid Group, Vinyl Monomer Containing Quaternary Ammonium Base, and Vinyl Chloride Monomer Instead of N, N-dimethylaminopropylacrylamide alone 100 parts by weight of sodium ethylene sulfonate and 2
-Copolymer E was obtained in the same manner as in (3) except that 40 parts by weight of sodium acrylamido-2-methylpropanesulfonate was used. The polymerization degree and composition of the obtained copolymer E are shown in Table 1.

(6) Polymerization of Copolymer F of Epoxy Group-Containing Vinyl Monomer and Vinyl Chloride Monomer [Initial Charge] Methanol (reagent 1 was added to a stainless steel autoclave with an internal volume of 18 liter equipped with a stirrer.
7500 parts by weight, 25 parts by weight of t-butylperoxyneodecanoate as a polymerization initiator were charged, and the mixture was evacuated with an aspirator for 5 minutes to remove residual air, and then 2600 parts by weight of vinyl chloride monomer were added. I prepared it.

[Preparation of post-addition] After removing air from a 3 liter suspendable stainless steel container (hereinafter referred to as an addition container), 300 parts by weight of glycidyl methacrylate,
1000 parts by weight of methanol was suctioned, and 1550 parts by weight of vinyl chloride monomer was further injected. The addition container was shaken to sufficiently mix and dissolve the contents and hung on a spring balance, and was connected to an addition nozzle provided in the polymerization reaction container from a valve at the bottom of the container using a flexible tube.

[Polymerization reaction operation] The rotation speed of the stirrer of the polymerization reactor was set to 250 rpm, 62 parts by weight of the mixed solution was added from the addition container to the polymerization reactor, and warm water was passed through the jacket so that the internal temperature of the reactor was 53 ° C. The temperature was raised to. Inner temperature is 5
When the temperature reached 3 ° C., 62 parts by weight of the mixed solution was added from the addition container to the polymerization reaction container, and then 50 parts by weight × 3 times, 63 parts by weight × 10 times, every 5 minutes depending on the progress of the polymerization reaction. 6
0 parts by weight × 13 times, 53 parts by weight × 22 times, 48 times in total, were added in portions. Further, the internal temperature of the polymerization reactor was raised and the temperature was adjusted from the time when it reached 53 ° C., so that it was kept constant at 53 ° C. during the reaction. Five minutes after the last addition was completed, the internal temperature was cooled to 25 ° C. to stop the polymerization reaction. After cooling, the vinyl chloride monomer remaining inside the polymerization reactor was discharged, and nitrogen gas was further aerated to sufficiently remove the vinyl chloride monomer. Then, the slurry was extracted from the lower part of the polymerization reactor, filtered, and vacuum dried at 50 ° C. for 10 hours to obtain 1500 parts by weight of a white powder of Copolymer F. The polymerization degree and composition of the obtained copolymer F are shown in Table 1.

(7) Polymerization of Copolymer G of Epoxy Group-Containing Vinyl Monomer, Hydroxyl Group-Containing Vinyl Monomer and Vinyl Chloride Monomer 100 parts by weight of lactone methacrylate and 3 parts of glycidyl methacrylate 3 instead of glycidyl methacrylate alone.
A copolymer G was obtained in the same manner as in (6) except that 100 parts by weight was used. The degree of polymerization and the composition of the obtained copolymer G are shown in Table 1.

(8) Polymerization of Copolymer H of Vinyl Chloride Monomer Containing Epoxy Group and Vinyl Chloride Monomer [Initial Charge] Methanol (reagent 1 was added to a stainless steel autoclave with an internal volume of 18 liter equipped with a stirrer.
7500 parts by weight and allyl glycidyl ether 400
After charging 35 parts by weight of t-butylperoxyneodecanoate as a polymerization initiator, 5 parts by an aspirator were used.
It was evacuated for a minute to eliminate residual air and then charged with 2600 parts by weight of vinyl chloride monomer.

[Post-addition preparation] After removing air from a 3 liter suspendable stainless steel container (hereinafter referred to as an addition container), 100 parts by weight of n-butyl acrylate and 1000 parts by weight of methanol were sucked and further vinyl chloride monomer was added. 1750 parts by weight were pressed in. The addition container was shaken to sufficiently mix and dissolve the contents and hung on a spring balance, and was connected to an addition nozzle provided in the polymerization reaction container from a valve at the bottom of the container using a flexible tube.

[Polymerization reaction operation] The rotation speed of the stirrer of the polymerization reactor was set to 250 rpm, 62 parts by weight of the mixed solution was added from the addition container to the polymerization reactor, and warm water was passed through the jacket so that the internal temperature of the reactor was 53 ° C. The temperature was raised to. Inner temperature is 5
When the temperature reached 3 ° C., 62 parts by weight of the mixed solution was added from the addition container to the polymerization reaction container, and then 50 parts by weight × 3 times, 63 parts by weight × 10 times, every 5 minutes depending on the progress of the polymerization reaction. 6
0 parts by weight × 13 times, 53 parts by weight × 22 times, 48 times in total, were added in portions. Further, the internal temperature of the polymerization reactor was raised and the temperature was adjusted from the time when it reached 53 ° C., so that it was kept constant at 53 ° C. during the reaction. Five minutes after the last addition was completed, the internal temperature was cooled to 25 ° C. to stop the polymerization reaction. After cooling, the vinyl chloride monomer remaining inside the polymerization reactor was discharged, and nitrogen gas was further aerated to sufficiently remove the vinyl chloride monomer. Then, the slurry was taken out from the lower part of the polymerization reactor, filtered, and then vacuum dried at 50 ° C. for 10 hours to obtain 1600 parts by weight of a white powder of copolymer H. The degree of polymerization and the composition of the obtained copolymer H are shown in Table 1.

(9) Polymerization of Copolymer J of Epoxy Group-Containing Vinyl Monomer, Carboxyl Group-Containing Vinyl Monomer, Hydroxyl Group-Containing Vinyl Monomer, and Vinyl Chloride Monomer Instead of glycidyl methacrylate alone, maleic acid is used. Acid 1
A copolymer J was obtained in the same manner as in (6) except that 2 parts by weight, 250 parts by weight of glycidyl methacrylate and 100 parts by weight of 2-hydroxypropyl acrylate were used. The polymerization degree and composition of the obtained copolymer J are shown in Table 1.

(10) Polymerization of copolymer K of a vinyl monomer having an epoxy group, a vinyl monomer having a sulfonic acid group, and a vinyl chloride monomer: 300 parts by weight of allyl glycidyl ether instead of sodium vinyl sulfonate alone And vinyl sulfonic acid seeder 2
A copolymer K was obtained in the same manner as in (1) except that 100 parts by weight was used. The polymerization degree and composition of the obtained copolymer K are shown in Table 1.

(11) Polymerization of Copolymer L of Vinyl Monomer Containing Epoxy Group, Vinyl Monomer Containing Hydroxyl Group, Vinyl Monomer Containing Quaternary Ammonium Base, and Vinyl Chloride Monomer Glycidyl methacrylate alone Instead, 100 parts by weight of 2-hydroxypropyl acrylate, 300 parts by weight of glycidyl methacrylate and 60 parts by weight of methacryloyloxyethyltrimethylammonium chloride were used to obtain a copolymer L in the same manner as in (6).
The polymerization degree and composition of the obtained copolymer L are shown in Table 1.

(12) A vinyl monomer containing an epoxy group and a vinyl monomer containing a tertiary amine group,
Polymerization of Copolymer M with Vinyl Chloride Monomer Copolymerization in the same manner as (6) except that 20 parts by weight of N, N-dimethylaminopropyl acrylamide and 300 parts by weight of glycidyl methacrylate were used instead of glycidyl methacrylate alone. A combined M was obtained. The polymerization degree and composition of the resulting copolymer M are shown in Table 1.

(13) Polymerization of Copolymer N of Epoxy Group-Containing Vinyl Monomer, Phosphoric Acid Group-Containing Vinyl Monomer, Hydroxyl Group-Containing Vinyl Monomer, and Vinyl Chloride Monomer Instead of glycidyl methacrylate alone, Maleic acid 2
A copolymer N was obtained in the same manner as in (6) except that 5 parts by weight, 250 parts by weight of glycidyl methacrylate and 120 parts by weight of n-butyl acrylate were used. The polymerization degree and composition of the resulting copolymer N are shown in Table 1.

(14) Polymerization of Copolymer N of Vinyl Monomer Having Epoxy Group, Vinyl Monomer Having Carboxyl Group, and Vinyl Chloride Monomer Instead of glycidyl methacrylate alone, maleic acid 2
A copolymer O was obtained in the same manner as in (6) except that 5 parts by weight, 250 parts by weight of glycidyl methacrylate and 120 parts by weight of n-butyl acrylate were used. The degree of polymerization and the composition of the obtained copolymer O are shown in Table 1.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

(Examples 1 to 18 and Comparative Examples 1 to 8) [Preparation of Magnetic Paint] Copolymers A, B, C, D, E, F,
G, H, J, K, LM, N and O are mixed in the ratios shown in Tables 4 to 6, and the copolymer becomes 15% by weight in a mixed solvent of toluene / methyl ethyl ketone (weight ratio 1: 1). To the thus-dissolved solution, 6.5 parts by weight of metal powder (BET value 55 m ² / g) and an isocyanate compound (“Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), which is 4 times the weight of the copolymer (weight), are added. It was shaken and dispersed for 6 hours in a conditioner (manufactured by Red Devil Co.) to prepare a magnetic paint. In addition to the magnetic paint, a paint having the same composition as the magnetic paint was separately prepared except that no metal powder was added. [Measurement of Physical Properties of Magnetic Paint] The following physical properties of the magnetic paint were measured, and the results are shown in Tables 4 to 6. (1) Glossiness The above magnetic paint is applied on a polyester film, oriented,
A magnetic coating film was prepared by drying and allowing sufficient crosslinking reaction. For this magnetic coating film, the glossiness at an incident angle and a reflection angle of 60 degrees was measured using a digital variable angle gloss meter (“VG-1G” manufactured by Nippon Denshoku Industries Co., Ltd.). (2) Squareness Ratio The sample whose glossiness was measured was cut into a size of 4.5 × 7 cm, and a direct current magnetization characteristic recording device (“T /
3256-30 "). (3) Powder drop test The magnetic coating film prepared in (1) was brought into contact with a steel rod (surface roughness Ra = 0.6 μm) rotating at 960 rpm for 1 hour under a constant load (100 g), and the weight at that time The amount of the weight loss was measured as the amount of powder falling and the strength of the magnetic coating film was compared. (4) Viscosity measurement The magnetic paint was measured with an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., for high viscosity). (5) Gel Fraction A coating material containing no metal powder is applied onto a polyester film, dried, and then the polyester film is peeled off.
A paint film was prepared. The gel fraction was calculated from the weight of the film after being immersed in a mixed solvent of toluene / methylisobutylketone at 50 ° C. for one day and the weight of the film before the immersion. (6) Tensile strength Using the paint film prepared in (5), the tensile strength was measured by a tensile tester ("AUTOGRAPH" manufactured by Shimadzu Corporation). (7) Dehydrochlorination amount 1% of the vinyl chloride resin binder resin prepared above
The amount of hydrochloric acid generated at the time of thermal decomposition under the condition of 80 ° C. was measured.

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

The constitution of the binder resin composition for vinyl chloride-based magnetic recording of the present invention is as described above, has an excellent affinity with magnetic powder, and can be filled with magnetic powder in high density and high orientation, It is easy to design various resins according to the required quality, and it is possible to provide a wide variety of magnetic paints. 2 of the present invention
The magnetic recording medium of (1) has a magnetic coating film having excellent electromagnetic characteristics, heat resistance, durability, and abrasion resistance, and thus is suitable for use in magnetic tapes, magnetic disks, magnetic cards and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Nakachi 12-24 Sakane-cho, Shinnanyo-shi, Yamaguchi Prefecture

Claims (2)

[Claims] 1. A ratio of at least two kinds selected from the following copolymers (I), (II) and (III), in which none of the copolymers exceeds 95% by weight. 1. A vinyl chloride-based binder resin composition for magnetic recording, comprising: (I) A copolymer of at least one vinyl monomer of a vinyl monomer having an epoxy group and a vinyl monomer having a hydroxyl group, and a vinyl chloride monomer. (II) Vinyl monomer containing SO ₃ M ¹ group (M ¹ represents hydrogen, NH ₄ ⁺ or an alkali metal), PO ₂ (OM
² ) a vinyl monomer containing ₂ groups (M ² represents hydrogen, an alkali metal or a hydrocarbon group), a vinyl monomer containing a tertiary amine group, a vinyl monomer containing a quaternary ammonium salt group, a carboxyl group A copolymer of a vinyl monomer containing at least one functional group selected from the group consisting of a vinyl monomer containing and a vinyl monomer containing a hydroxyl group, a vinyl monomer containing an epoxy group, and a vinyl chloride monomer. (III) Vinyl monomer containing SO ₃ M ³ group (M ³ is hydrogen, NH ₄ ⁺ or alkali metal), vinyl monomer containing tertiary amine group and vinyl monomer containing quaternary ammonium salt group A copolymer of a vinyl chloride monomer having at least one functional group selected from the group consisting of and a vinyl chloride monomer. 2. A magnetic recording medium in which a magnetic layer made of magnetic powder and a binder resin composition is formed on one surface of a support and a non-magnetic layer made of a binder resin composition is formed on the other surface of the support. At least one of the
A magnetic recording medium comprising the vinyl chloride-based binder resin composition for magnetic recording according to claim 1.