JPS5953308B2 - Magnetic paint and its manufacturing method - Google Patents

Description

Detailed Description of the Invention The present invention relates to vinyl chloride, carboxylic acid vinyl ester, endo-bicyclo[2.2.1]-5-heptene-2.3
The present invention relates to a magnetic paint for magnetic recording media containing a vinyl chloride copolymer solution consisting of dicanoleboxylic anhydride (hereinafter referred to as hymic anhydride) and an unsaturated carboxylic acid, a thermosetting resin, magnetic powder, etc., and a method for producing the same.

Generally, magnetic recording media such as magnetic tapes and magnetic cards are manufactured by coating a substrate such as a polyester film or sheet with a dispersion coating in which magnetic powder, thermoplastic magnetic resin, and thermosetting resin are dissolved and dispersed in an organic solvent.

As thermoplastic resins that are raw materials for such magnetic paints, vinyl chloride copolymers, vinylidene chloride copolymers, acrylic ester copolymers, methacrylic acid copolymers, etc. have been proposed, and specific examples of these resins are listed below. Examples include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate alcohol terpolymer, and vinyl chloride-vinyl acetate-maleic acid terpolymer. However, when producing magnetic paint using these resins, there are issues with the mixability of the magnetic powder and thermoplastic resin, the mixability when thermosetting resins such as urethane resin are added, and the type of substrate to be coated. There are advantages and disadvantages, such as the affinity for the resin, the state of the resulting coating film, and the physical properties as a paint, and it is difficult to simultaneously satisfy the necessary physical properties with one type of resin. For example, vinyl chloride monovinyl acetate copolymer has poor reactivity with urethane resins, and when a magnetic paint using this copolymer is applied to a substrate, the paint film peels off, making it impractical for use in magnetic recording media.

In addition, vinyl chloride monoacetate-vinyl alcohol terpolymer has good dispersibility of magnetic powder and excellent reactivity with urethane resin, but when it is used to make magnetic paint, a paint with a so-called short pot life can be obtained. and the workability is poor.
When applying this to a substrate such as a polyester sheet or film, the viscosity of the paint increases over time, so when adjusting the paint, it is necessary to lower the paint viscosity from the beginning by increasing the amount of organic or organic solvent added. It is not possible to adjust a large amount of paint at once. In addition, the general vinyl chloride monoacetate vinyl maleic acid terpolymer has a limit in maleic acid content, and if it is too large, a clear solution cannot be obtained, and furthermore, it interferes with the crosslinking reaction of urethane resin. Therefore, the amount is about 1%, and the dispersibility of the magnetic powder is insufficient at this amount.

The vinyl chloride copolymer of the present invention does not have these drawbacks. A vinyl chloride copolymer solution that solved the problem, namely Shiohana f-nyl,
This is a quaternary copolymer solution prepared by copolymerizing vinyl kanomate, heimic anhydride, and unsaturated carboxylic acid in a specific ratio.

This is a vinyl chloride-carboxylic acid ester copolymer system.
As a result of copolymerizing a specific amount of unsaturated carboxylic acid and hymic anhydride blended in a specific ratio, the effect of improving the dispersibility of magnetic powder possessed by unsaturated carboxylic acids is fully expressed, and the When used in combination, it does not interfere with the crosslinking reaction of the urethane resin, and when applied to polyester seals or films, a smooth coating can be obtained, and when dried to make magnetic tape, it can be used under adverse conditions of high temperature and high humidity. A vinyl chloride copolymer solution that has excellent properties such as no blocking property even when left under water and is suitable for magnetic paints can be obtained. Furthermore, the quaternary copolymer solution according to the present invention, especially the copolymer solution containing heimic anhydride, has better storage stability than common copolymer solutions based on vinyl chloride, carboxylic acid vinyl ester, and maleic anhydride. Excellent.

For example, a typical terpolymer solution of vinyl chloride, carboxylic acid vinyl ester, and maleic anhydride is
If stored for ~6 months, a decomposition reaction of dehydrochlorination will gradually occur and a small amount of polyene will be produced, causing the colorless and transparent solution to turn brown to blackish brown, and the acid value will become high, making it unusable. In contrast, the quaternary copolymer solution according to the present invention does not undergo a dehydrochloric acid reaction even after being stored for 18 to 24 months after production, and can maintain a colorless and transparent solution state and is stable. Its resin composition allows it to be used for a long period of two years or more. The present invention will be explained in more detail below. The present invention is a resin solution having an average degree of polymerization of 100 to 400, which is obtained by copolymerizing the four monomers mentioned above in a specific ratio. As the captive component vinyl chloride of the present invention, ordinary commercially available products can be used. Examples of carboxylic acid vinyl esters as component (B) to be copolymerized with vinyl chloride include vinyl acetate, vinyl propionate, vinyl versatate (Ciel Mori product name), vinyl stearate, etc. Among these, acetic acid Vinyl is preferred. Component (6), Himicic Anhydride, is easily available from Hitachi Chemical Co., Ltd. under the trade name "Himicmic Anhydride." The unsaturated carboxylic acids of component (D) include maleic acid, itaconic acid, fumaric acid, acrylic acid, and methacrylic acid, and among these, maleic acid is the most threatening. In the present invention, a solution polymerized copolymer of vinyl chloride as the captive component, vinyl acetate as the 8th component, hymic anhydride as the 6th component, and maleic acid as the 9th component is desirable. Next, the composition ratio of each monomer in the copolymer will be explained.

In the copolymer of the present invention, vinyl chloride is contained in an amount of 50 to 85% by weight, preferably 55 to 80% of the sum of vinyl chloride and component (B) carboxylic acid vinyl ester.

If vinyl chloride exceeds 85% of the sum of vinyl chloride and carboxylic acid vinyl ester, the solution viscosity will increase due to mixing with magnetic powder, so it is necessary to lower the paint viscosity when applying the magnetic paint to the substrate, and a large amount solvent must be used. On the other hand, if the amount of carboxylic acid vinyl ester exceeds 50% by weight, the strength of the coating film surface will be weak, and the coating film may peel or block, which is undesirable. In addition, (the O component, hymic anhydride, is 60 to 95% by weight of the sum of the unsaturated carboxylic acid and hymic anhydride, preferably 70 to 9% by weight)
Contains 0%.

When the amount of hymic anhydride exceeds 95% of the sum of hymic anhydride and unsaturated carboxylic acid, the dispersibility of the magnetic powder decreases. On the other hand, if the unsaturated carboxylic acid exceeds 40% by weight, the reaction with the thermosetting resin will be too rapid, resulting in a short pot life.
In addition, the total amount of unsaturated carboxylic acid and hymic anhydride is 1 by weight, and the total amount of vinyl chloride and carboxylic acid vinyl ester is 1
00, if it is less than 1, the reactivity with the thermosetting resin will be weak, while if it exceeds 5, the reactivity with the thermosetting resin will be rapid, and the pot life of the paint will be short, making it impossible to put it into practical use.

In addition, the average degree of polymerization of the vinyl chloride copolymer is 100 to 400.
The reason for this is: When this is applied as a magnetic paint to a substrate, if the average degree of polymerization is less than 100, the coating surface will be weak and it is not practical.

Moreover, if it exceeds 400, the viscosity of the paint becomes high, making it difficult to apply a highly concentrated solution. Note that, in view of the properties of the coating surface, the coating material, etc., it is particularly preferable that the vinyl chloride copolymer has an average degree of polymerization of 200 to 400. The vinyl chloride copolymer according to the present invention is dissolved in an organic solvent solution, and examples of organic solvents include esters such as ethyl acetate and butyl acetate, acetone, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and xylene. ,
Examples include aromatics such as toluene.

These organic solvents can be used alone or in combination. Furthermore, the ratio of the vinyl chloride copolymer to the organic solvent cannot be specified because it changes depending on the conditions of use, but generally the vinyl chloride copolymer according to the present invention is produced by solution polymerization. Since it can be used as it is for magnetic paints, etc., the amount that can be polymerized in solution (30 to 7
The amount of organic solvent may be 0% by weight), and it may be diluted with an organic solvent as necessary. Therefore, it is preferable to use an organic solvent suitable for the intended use during solution polymerization. Next, to explain the method for producing the vinyl chloride copolymer solution of the present invention, first, as a polymerization procedure, vinyl chloride and vinyl acid vinyl ester are charged into a polymerization can so as to have the above-mentioned copolymer composition. An oil-soluble initiator and a solvent are charged, heated, and polymerized under pressure.

Next, hymic acid anhydride and unsaturated carboxylic acid may be added all at once at the beginning of polymerization, but it is also possible to add a portion at the beginning of polymerization or before the start of polymerization and add the remainder in portions as polymerization progresses, or to divide the entire amount. It is better to add (O component and (D)
Since the components are well dispersed in the polymer composition and a homogeneous copolymer can be obtained, it is more preferable in terms of dispersibility with magnetic powder and reaction rate with urethane resin. According to the research conducted by the present inventors, it is important to wait until the polymerization rate reaches 5 to 70%, and even if the entire amount is added at least twice during this period, it becomes noticeable when used in magnetic paints. Improvements in physical properties can be seen. If this solution is used as it is as described above, it is economical and saves energy, but if necessary, the organic solvent may be removed from it by an appropriate means, and the powdered form may be dissolved in an organic solvent at the time of use. .

When the vinyl chloride copolymer solution of the present invention is used as a magnetic paint, the thermosetting resin may include urethane resin, epoxy resin,
Phenol resins are suitable, and when polyester resins are used as the substrate, urethane resins are suitable. To produce a magnetic paint using the vinyl chloride copolymer resin solution obtained in this way, 200 to 600 parts by weight of magnetic iron oxide, preferably 300 to 600 parts by weight, per 100 parts by weight of the solid content of the vinyl chloride copolymer resin solution. 500 parts by weight, organic solvent 600
About 1200 parts by weight, preferably 800 to 1000 parts by weight, and 5 to 50 parts by weight of thermosetting resin, preferably 10 to 30 parts by weight may be added.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 140 parts by weight of vinyl chloride, 60 parts by weight of vinyl acetate, 105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene and 2 parts by weight of benzoyl peroxide were charged into an autoclave, and polymerization was started at a temperature of 55°C.

When the polymerization rate of vinyl chloride monoacetate reached 10%, 1/6 of a mixed solution consisting of 4.5 parts by weight of hymic anhydride, 1.5 parts by weight of maleic acid, and 30 parts by weight of methyl ethyl ketone was added. . The remaining 5/6 has the above polymerization rate of 60%
It was added in portions until the The mixture was polymerized to a polymerization rate of 90% and cooled, and the resulting resin solution having a resin fat content of about 50% by weight was taken out. As a result of analysis, this resin composition was found to be vinyl chloride 75
Parts by weight, 25 parts by weight of vinyl acetate, 2 parts by weight of hymic anhydride.
It was a copolymer of 3 parts by weight and 0.7 parts by weight of maleic acid with a degree of polymerization of 220. A magnetic paint was produced using this copolymer according to the gloss measurement method described below, and was applied onto a polyester film substrate.

This copolymer, magnetic paint, and coated polyester film were tested according to the measurement methods and standards described below, and are shown in Table 1. Measurement method and criteria 1) Compatibility Copolymers obtained in Examples and Comparative Examples (calculated as solid content)
100 parts by weight Product name Coronate L (urethane resin) 2
A blended solution consisting of 300 parts by weight of 0 parts by weight of methyl ethyl ketone was prepared, and a transparent product was rated ○, a translucent product was Δ, and an opaque product was rated ×.

Copolymers obtained in the 2-pack sample and comparative example (in terms of solid content)
100 parts by weight Magnetic iron oxide powder 400 parts by weight Methyl ethyl ketone 300 parts by weight; Methyl isobutyl ketone 30
0 parts by weight Toluene 300 parts by weight Product name Coronate L (
Urethane resin) 20% by weight Product name Lecithin (soybean oil) 2 parts by weight. character,,. i
! -Ra◆To include! The magnetic paint obtained by thorough mixing is applied to a polyester film substrate to a dry film thickness of 10 μm, and dried at 100° C. for 1 minute.

Further, the magnetic coating film is pressed under conditions of 90° C. x 30 seconds x 2 kg/d to impart smoothness. this. The reflectance of the magnetic coating film at a reflection angle of 60° C. is measured using a gloss meter. 3) Pot life of magnetic paint The same magnetic paint used for the above gloss measurement was collected in a small bottle, and the time until the paint lost its fluidity (gelatinized) in a constant temperature bath at 25°C was measured to determine the pot life. .

4) Blocking property The same magnetic paint used in the above gloss measurement was applied to a polyester film substrate so that the film thickness after drying was 10μ, dried at a temperature of 100°C for 1 minute, and then 2kg/
- Apply a load and leave the film at 60°C and 90% humidity for 24 hours, then peel off the film.

Those that were easily peeled off were rated ○, those that were slightly sticky were rated △, and those that were sticky were rated ×. 5) Adhesion The same magnetic paint used in the above gloss measurement is applied to a polyester film substrate so that the film thickness after drying is 10 μm, and dried at a temperature of 100° C. for 1 minute.

Apply Zero Tape (trade name) to this coating, rub it strongly with your fingers, and then peel it off. At this time, when the magnetic coating film did not adhere to the zero tape, the adhesion was ○, when the coating film slightly adhered, it was rated Δ, and when the coating film adhered and peeled off, it was rated x.
6) Place the storage-stable copolymer resin solution in an oil can, seal it tightly, and leave it at room temperature. Remove the contents every three months. Those with no discoloration of the resin solution are marked as ○, and those with a slight yellow discoloration. The sample was rated as △, and the sample that changed color to blackish brown was graded as x.

The following Examples and Comparative Examples were also tested in accordance with the above method.

Example 2 Example 1 except that the type of monomer and the charging ratio were variously changed.
A thermoplastic copolymer and magnetic paint were obtained in the same manner as above.

These conditions and test results are shown in Table 1. Example
3. Charge 140 parts by weight of vinyl chloride, 60 parts by weight of vinyl acetate, 105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene, 2 parts by weight of benzoyl peroxide, 1.13 parts by weight of himitutaic anhydride, and 0.37 parts by weight of maleic acid. , polymerization started at a temperature of 55°C.

When the polymerization rate of vinyl chloride monovinyl acetate reaches 10%, 3.39 parts by weight of hemicic anhydride and 1.1 parts by weight of maleic acid
1/3 of a mixed solution consisting of 1 part by weight and 30 parts by weight of methyl ethyl ketone was added. The remaining 2/3 was added in portions until the polymerization rate reached 30%. Polymerize to a polymerization rate of 90%, cool,
The resulting colorless and transparent resin solution was taken out.

The resin composition and degree of polymerization were the same as in Example 1. The test results were compatibility: ○, and gloss when made into magnetic paint: 9
1%, pot life 240 hours or more, blockability ○
, Adhesion was ○. Example 4 140 parts by weight of vinyl chloride, 60 parts by weight of vinyl acetate, 105 parts by weight of methyl ethyl ketone, 45 parts by weight of toluene. Department,
Peroxide Sanzoil 21 quantity, Anhydrous Hymi. Tsuku-A. i
Parts by weight of the polymer and parts by weight of the polymer were charged into an autoclave, and polymerization was started at a temperature of 55°C.

Polymerize vinyl chloride monovinyl acetate until the polymerization rate is 90%, cool it, and take out the resulting colorless and transparent resin solution. Ta. The resin composition and degree of polymerization were the same as in Example 1. The test results were compatibility: △, and gloss when made into magnetic paint: 87
%, pot life 100 hours, blocking property ○, and adhesion property ○. Example 5 Example 4 except that itaconic acid was used instead of maleic acid.
A copolymer was obtained in the same manner as above.

The composition of the resulting resin was 75 parts by weight of vinyl chloride, 25 parts by weight of vinyl acetate, 40 parts by weight of hemicic anhydride, and 1.0 parts by weight of itaconic acid, and the degree of polymerization was 200. The test results were compatibility: △, gloss when made into magnetic paint: 85
%, pot life 130 hours, blocking property ○, and adhesion property ○. Comparative Example 1 In place of the copolymer resin according to the present invention, a commercially available vinylite resin VAGH (trade name manufactured by Union Carbide Company, USA; monomer ratios are shown in Table 2) was used, and the gloss test method described in (2) above was carried out. A magnetic paint was produced in the same manner as above and applied to polyester film.

Each physical property was measured according to the measurement method described above, and the results are shown in Table 2. Comparative Example 2 A magnetic paint was obtained in the same manner as in Comparative Example 1, except that the vinylite resin VAGH was replaced with the vinylite resin VMCH (product name manufactured by Union Carbide, USA; monomer ratios are shown in Table 2), and applied to a polyester film. .

Each physical property was measured and the results are shown in Table 2. Comparative example
3 A copolymer resin was obtained in the same manner as in Example 1 except that the types of monomers and the charging ratio were changed as shown in Table 2.

Claims (1)

[Scope of Claims] 1 (A) Vinyl chloride (B) Carboxylic acid vinyl ester (c) Endo-bicyclo[2.2.1]-5-heptene-2.3 dicarboxylic anhydride (D)
A magnetic paint containing a copolymer made of unsaturated carboxylic acid, a thermosetting resin, magnetic powder, and an organic solvent. 2 Component (A) of the copolymer contains 50 to 85% of the sum of each component (A) and (B), and component (C) contains 60 to 95% of the sum of each component (C) and (D). and (A) and (B
)) for a total of 100 parts by weight of each component, (C) and (D)
The sum of each component is 1 to 5 parts by weight, and the average degree of polymerization is 10
0 to 400. The magnetic paint according to claim 1. 3 Component (A), vinyl chloride, component (B), and carboxylic acid vinyl ester are charged together with an organic solvent and an oil-soluble polymerization initiator, and a predetermined amount of component (C) and endo-bicyclo[
2.2.1] -5-heptene-3 dicarboxylic acid, component (D), and unsaturated carboxylic acid are added in portions, or a portion is added at the initial stage of polymerization and the remainder is added in portions. A method for producing a magnetic paint, in which a vinyl chloride copolymer solution for magnetic paint is obtained by solution polymerization, and a thermosetting resin, a magnetic component, and an organic solvent are mixed in the copolymer solution. 4. To obtain a vinyl chloride copolymer solution for magnetic paint, predetermined amounts of component (C) and component (D) were added at a polymerization rate of 70.
%, the method for producing a magnetic paint according to claim 3, wherein the magnetic paint is added in at least two or more portions until the amount is reached. 5. When obtaining a vinyl chloride copolymer solution for magnetic paint, the (A) component of the copolymer is 50 to 85% of the sum of each component (A) and (B), and the (C) component is (C). Contains 60 to 95% by weight of the sum of each component (D), and 100 parts by weight of the sum of each component (A) and (B), (C) and (D)
) is 1 to 5 parts by weight, and the average degree of polymerization is 1.
00 to 400. A method for producing a magnetic paint according to claim 3 or 4.