JP2632430B2 - Magnetic ink for vinyl chloride magnetic cards - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a magnetic ink for a vinyl chloride-based magnetic card, and more particularly, to a non-curl adhesion coating when applied to a polyvinyl chloride-based sheet as a card base material. The present invention relates to a magnetic ink capable of forming a film.

[Conventional technology]

Magnetic cards are widely used as prepaid cards such as cash cards, credit cards, commuter passes, telephone cards, and orange cards. These magnetic cards generally have a stripe or a magnetic layer on the entire surface of one side of the base such as paper or plastic film, and print characters and pictures on the other part, and visual information according to the usage conditions. The layer is finished to a predetermined size by processing such as addition of a print layer or embossing for displaying the information, and information is magnetically recorded on the magnetic layer as needed, and the magnetic layer is used.

Sheets such as polyvinyl chloride, polyethylene terephthalate (PET), and paper are used as the base, and magnetic inks for providing a magnetic layer on the base include, for example, acrylic resins, polyurethane resins, polyester resins, and butyral resins. , A synthetic resin such as a vinyl chloride-vinyl acetate copolymer as a binder, for example, γ-Fe
₂ O ₃ , magnetic particles such as Co-coated γ-Fe ₂ O ₃ and other components as required, such as a surfactant, a silane coupling agent, a plasticizer, a wax, a silicone oil, and a pigment, are added.
What was prepared by kneading with a three-roll mill, a sand mill, a ball mill or the like is used.

[Problems to be solved by the invention]

Among the above-mentioned magnetic cards, relatively thin polyvinyl chloride sheets are frequently used as a base for orange cards, telephone cards, ski lift tickets, and the like.

However, when such a thin polyvinyl chloride sheet is used as a substrate and a magnetic ink using toluene / methyl ethyl ketone or the like as a solvent is applied to the substrate, the polyvinyl chloride sheet of the substrate is attacked by the solvent of the magnetic ink, and as time passes. There is a problem that warpage (curl) occurs.

For this reason, the use of a magnetic ink using an alcohol-based solvent that does not attack the polyvinyl chloride sheet has been attempted, but in this case, a polyamide-based resin soluble in an alcohol-based solvent, cellulose as a binder resin, Resin,
Since a specific resin such as a butyral-based resin must be used in a limited manner, there is a drawback that a magnetic ink having a performance satisfying the adhesiveness cannot be obtained.

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, when a polyurethane polyurea resin soluble in an alcoholic solvent is used as a binder for a magnetic ink, the adhesion is very good, and The present inventors have found that the warping phenomenon of the polyvinyl chloride sheet can be effectively reduced, and have completed the present invention.

[Means for solving the problem]

That is, the magnetic ink for a vinyl chloride-based magnetic card provided by the present invention is mainly composed of a polyurethane polyurea resin obtained by reacting a diisocyanate compound represented by the following general formula as a binder for ferromagnetic particles, It is characterized by being dissolved in an organic solvent containing 10 to 80 parts by weight of an alcohol having 1 to 4 carbon atoms.

 Hereinafter, the present invention will be described in detail.

In the present invention, the polyurethane polyurea resin used as a binder for the magnetic ink is obtained by chain-extending a terminal isocyanate prepolymer, which is a reaction product of a bifunctional polyol and a diisocyanate compound represented by the following general formula, with a diamine. Things apply.

General formula Any conventionally known bifunctional polyol can be used, and specifically, ethylene glycol, butanediol, 1,6-hexanediol, 3-methyl-1,5-
Polyester polyols obtained by reacting a diol such as pentanediol or a mixture thereof with a dicarboxylic acid, for example, adipic acid, sebacic acid, phthalic acid, isophthalic acid, etc .; polytetramethylene glycol, polycaprolactone glycol, polypropylene glycol; Alkylene oxide adducts of diols, propylene oxide adducts of bisphenol A; polyester polyols and polycaprolactone copolymerized polyols, valerolaton polyols; monoalkylene oxide adducts, oleylamine-propylene oxide adducts, and mixtures thereof. Can be Such a bifunctional polyol having a molecular weight of about 400 to 4,000 and an OH value of about 280 to 28 is preferable in the present invention.

The diisocyanate compound to be reacted with the bifunctional polyol is represented by the above structural formula,
-Bis (α, α-dimethylisocyanatomethyl) benzene (TMXDI) or a compound called tetramethylxylylene diisocyanate. This diisocyanate compound may be used alone or other known diisocyanate compounds, for example, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), as long as the object of the present invention is not hindered. Xylene diisocyanate (XDI), water added
You may use together with XDI, diphenylmethane diisocyanate (MDI), etc.

The method for producing a full isocyanate prepolymer from a bifunctional polyol and a diisocyanate compound may be in accordance with a known method, and in an organic solvent or without using an organic solvent, at an equivalent ratio of NCO / OH = 2: 1.2. It is a method of reacting. Depending on the conditions of the reaction, especially the NCO / OH ratio, terminal isocyanate prepolymers of various molecular weights can be obtained. In the present invention, the molecular weight of the terminal isocyanate prepolymer is preferably in the range of about 800 to 8,000, and the NCO% is 10 to 1%. Range.

As the diamine used for the chain extension of the above terminal isocyanate prepolymer, any of conventionally known diamines can be used, and preferred specific examples thereof include, for example, diaminobenzene, 4,4-diaminodiphenylmethane, and water addition.
4,4-diaminodiphenylmethane, isophoronediamine, hexamethylenediamine, trimethylhexamethylenediamine, 1,3-bis (α, α-dimethylaminomethyl) benzene and the like can be mentioned. These diamines have an NCO / NH ₂ = 0.
It is preferable to use in the range of 8: 1.0.

The reaction between the two is preferably carried out in an organic solvent, by adding a diamine to the terminal isocyanate prepolymer solution, by adding a terminal isocyanate prepolymer to the diamine solvent, or by mixing both at the same time. You may. The reaction is preferably carried out at about 15 to 40 ° C. for 0.5 to 2 hours.

As the organic solvent used for the production of the above terminal isocyanate prepolymer and polyurethane polyurea resin,
A single or mixture of toluene, methyl ethyl ketone, ethyl acetate, isopropyl alcohol is used. However, alcohol-based solvents should not be used during the preparation of the terminal isocyanate prepolymer.

The polyurethane polyurea resin obtained as described above preferably has a molecular weight of about 15,000 to 100,000,
The obtained polyurethane polyurea resin solution can be used as it is.

The binder of the magnetic ink according to the present invention is mainly composed of the above-mentioned polyurethane polyurea resin, and can be used not only alone but also in combination with other resins. Examples of the resin used in combination include nitrocellulose, cellulose acetate, cellulose derivatives such as cellulose acetate butyrate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate -Vinyl chloride vinyl acetate resin such as maleic acid copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, flocculent polyester resin, (meth) acrylic acid-acrylonitrile copolymer, (meth) acrylic Acid-acrylonitrile copolymer, polyvinyl acetal, polyvinyl butyral,
Phenoxy resins, epoxy resins, polyamide resins, and the like.

Such a binder component is used in a ratio of 10 to 50 parts by weight, preferably 15 to 30 parts by weight, based on 100 parts by weight of the ferromagnetic powder. As ferromagnetic powders, γ-Fe ₂ O ₃ , Fe ₃ O ₄ , γ
-Fe ₂ O ₃ and Fe ₃ O ₄ mixed crystals, cobalt-doped gamma-Fe ₂ O
₃ , cobalt-doped Fe ₃ O ₄ , chromium dioxide, barium ferrite and the like.

Further, the magnetic ink of the present invention, if necessary, a dispersant,
Lubricants, reinforcing agents, antistatic agents and the like can be added. As the dispersant, a fatty acid having 12 to 18 carbon atoms such as capric acid and oleic acid linoleic acid, and an alkali metal salt or an alkaline earth metal salt of these fatty acids such as lecithin are used.

As the lubricant, a solid lubricant such as molybdenum disulfide or tungsten disulfide, silicone oil, or a fatty acid ester is used. As the reinforcing material, alumina, silicon carbide, chromium oxide, corundum or the like is used.

As the antistatic agent, carbon black, surfactant and the like are used.

It is necessary that the organic solvent for preparing the magnetic ink of the present invention contains alcohols having 1 to 4 carbon atoms such as methanol, ethanol, isopropanol and butanol in a proportion of 10 to 80 parts by weight in the organic solvent. . Other solvent components include aromatics such as toluene and xylene, hydrocarbons, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, ethylene glycol dimethyl ether and ethylene glycol monoethyl ether. Glycol ethers.

In the present invention, in particular, since the target is a film-like vinyl chloride sheet as a substrate, it is preferable to use the above-mentioned alcohol-based solvent as an essential component, and use it in combination with another solvent. A suitable mixing ratio of the solvent is roughly as follows.

Alcohols 10 to 80 parts by weight, aromatic hydrocarbons 10 to 50
Parts by weight, 0 to 20 parts by weight of ketones, 0 to 10 parts by weight of glycol ethers, 0 to 10 parts by weight of esters.

(Operation)

The polyurethane polyurea resin constituting the binder in the present invention is soluble in a solvent mainly composed of an alcohol having 1 to 4 carbon atoms, which does not invade the vinyl chloride sheet as a base, and Shows excellent adhesion to Through this action, when applied as a magnetic ink to a thin film-like vinyl chloride-based substrate, a coating film having extremely good adhesion is formed, and further, the warpage phenomenon with time hardly occurs.

〔Example〕

Hereinafter, the present invention will be described more specifically based on examples. All parts or percentages in the examples and comparative examples are based on weight.

Synthesis Example 1 Polytetramethylene glycol (56 OH group, molecular weight 2,000
0) 1 mol (1,000 parts) m-TMXDI 2 mol (244 parts) Tin-based catalyst 0.2 parts The above components were added and mixed in methyl ethyl ketone at a ratio of a solid content of 75%, and reacted at the boiling point of methyl ethyl ketone for 6 hours. Then add methyl ethyl ketone and add 50
% To obtain a terminal isocyanate prepolymer.
The molecular weight of this terminal isocyanate prepolymer is about 2,56
At 0, the NCO% was 1.64.

Next, 31.5 parts of isophorone diamine and 0.
25 parts, 26.6 parts of isopropyl alcohol and 48 parts of methyl ethyl ketone are placed in a reaction vessel, and while stirring at a temperature of 40 to 50 ° C., 100 parts of the above-mentioned 50% solution of terminal isocyanate prepolymer is added thereto, and a temperature of 50 to 60 ° C. For 2 hours to obtain a polyurethane polyurea resin. The molecular weight of the obtained polyurethane polyurea resin was about 43,200.

Synthesis Example 2 100 parts of a 50% solution of the terminal isocyanate prepolymer obtained in Synthesis Example 1 was placed in a reaction vessel, and stirred at a temperature of 30 to 40 ° C. while stirring 3.15 parts of isophorone diamine, 0.25 parts of dibutylamine 26.6 parts of isopropyl alcohol and 48 parts of methyl ethyl ketone was added and reacted at a temperature of 50 to 60 ° C. for 2 hours to obtain a polyurethane polyurea resin. The molecular weight of the obtained polyurethane polyurea resin was 48,400.

Example 1 Barium ferrite 30 parts Polyurethane polyurea resin obtained in Synthesis Example 1 40 parts Isopropyl alcohol 15 parts Toluene 15 parts The above composition was kneaded with a sand mill for 48 hours to obtain a magnetic ink.

Example 2 30 parts of γ-Fe ₂ O ₃ 40 parts of the polyurethane polyurea resin obtained in Synthesis Example 2 15 parts of isopropyl alcohol 15 parts of toluene The above composition was kneaded with a sand mill for 48 hours to obtain a magnetic ink.

Comparative Example 1 40 parts of γ-Fe ₂ O ₃ Polyamide resin (trade name; product of Reoamide S2600 Kao Corporation) 10 parts Ethanol 20 parts Toluene 30 parts The above-mentioned composition was kneaded with a sand mill for 48 hours to obtain a magnetic ink.

Comparative Example 2 Barium ferrite 30 parts Polyurethane resin (trade name: Daifelamin MAU5022 manufactured by Dainichi Seika Kogyo Co., Ltd.) 15 parts Toluene 25 parts Methyl ethyl ketone 30 parts The above composition was kneaded with a sand mill for 48 hours to obtain a magnetic ink.

The magnetic inks obtained in the above Examples and Comparative Examples were
After coating on a polyvinyl chloride sheet with a thickness of 10μ
After drying at 90 ° C. for 30 seconds, a magnetic card was produced. A curl test was performed on each of the obtained cards.
It is shown in the table.

The degree of curl in Table 1 was obtained by measuring the height (mm) of a sheet having a length of 300 mm and a width of 200 mm from a horizontal plane at four corners, and indicating the average value.

From the results shown in Table 1, it is recognized that the magnetic cards of Examples 1 and 2 have significantly reduced time-dependent changes in curl degree as compared with those of Comparative Examples 1 and 2 of the conventional configuration.

〔The invention's effect〕

The magnetic ink for a magnetic card of the present invention uses a special polyurethane polyurea resin as a binder component, and can be made into an ink with a solvent mainly composed of an alcohol-based solvent. Therefore, the vinyl chloride sheet is not invaded by the solvent of the ink, and the non-curl property is extremely good. In addition, since the binder has excellent adhesiveness, it is expected to be useful as a thin film magnetic ink for a prepaid card mainly composed of a polyvinyl chloride sheet.

Claims (2)

(57) [Claims] 1. A polyurethane polyurea resin obtained by reacting a diisocyanate compound represented by the following general formula as a binder for a ferromagnetic particle: 10 to 80 parts by weight of an alcohol having 1 to 4 carbon atoms A magnetic ink for a vinyl chloride magnetic card, which is dissolved in a contained organic solvent. 2. A polyurethane polyurea resin obtained by subjecting a terminal isocyanate prepolymer, which is a reaction product of a bifunctional polyol and a diisocyanate compound represented by the following general formula, to chain extension with a diamine. Item 6. A magnetic ink for a vinyl chloride magnetic card according to Item 1. General formula