JPS5835727A - Composition of aqueous magnetic painting agent - Google Patents

Abstract

PURPOSE:To obtain a thin magnetic recording layer with excellent recording and reproducing characteristics, by adding a high-polymer electrolyte and glycol ether in an aqueous magnetic painting composition. CONSTITUTION:To an aqueous dispersant obtained by uniformly mixing and dispersing, as required in common use of a dispersant, magnetic powder such as gamma- iron oxide powder to an aqueous resin binder, high-polymer electrolyte (0.2- 10.0 parts per 100 parts magnetic powder) such as sodium salts of carboxymethylcellulose, maleic anhydride copolymer, polyacrylic acid, polymethacrylic acid and alginic acid, their ammonium salt, polyvinylbenzyltrimethylammoniumchloride and polyvinylpyridine hydrochloric acid salt, and glycol ether (1.0-3.0 parts) such as ''methyl cellosolve '', ''propyl cellosolve '', ''butyl cellosolve '', tetrahydropyranemethanol, propylcarbinol, 1-butoxyethoxy-2-propanol, and diacetone alchohol, are added.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-based magnetic coating composition, and more specifically, for example, in the production of magnetic tickets, magnetic cards, magnetic recording sheets, etc., the water-based coating composition is applied to the surface of a support. The present invention aims to provide at a low cost a water-based magnetic coating composition that can have all of the desirable characteristics such as reading reproduction output, reverse reading reproduction output, and DC noise level.

Conventionally known magnetic coating agents of this type include magnetic agent powder (hereinafter referred to as magnetic powder) and an organic solvent-based binder such as vinyl chloride/vinyl acetate copolymer.

There are those made of polyester, epoxy resin, polyurethane, etc., and those made of magnetic powder and a binder such as water-soluble synthetic resin 1 synthetic resin latex (for example, Japanese Patent Application Laid-open No. 155506/1983). In its practical use, when it is applied (coated) on the surface of a support, unless the coating film is very thick, the desired reading reproduction output, reverse reading reproduction output, and DC noise level characteristics cannot be obtained. The problem was that the products fluctuated a lot in terms of quality and cost, making it difficult to obtain stable products on a regular basis.

This invention was developed based on the above-mentioned points, and as a result of various experimental studies on the relationship between magnetic powder and binder, the inventors of the present invention aimed to improve the above-mentioned drawbacks. In order for the aqueous magnetic composition (hereinafter referred to as an aqueous magnetic composition) to have the desired properties when applied, it is necessary that the aqueous magnetic composition consist of three main components: a magnetic powder, a polymeric preelectrolyte, and a glycol ether, and their blending ratio. Only when (composition) has an inseparable relationship (interrelated relationship) under certain conditions,
The present invention was completed based on the discovery that the intended purpose could be sufficiently achieved even if the coating film on the support was thin (approximately 40 to 70% of the conventional film thickness).

The magnetic powder used here is a known γ-iron oxide powder (average particle size 0.4μ), and a water-soluble resin binder such as acrylic, NBR, SBR, vinyl chloride/vinyl acetate copolymer, EVA, and polyurethane. It is not particularly different from the conventional case, but in this case, examples of dispersants such as sodium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, styrene maleic anhydride, naphthalene condensate, It is convenient to add one or two kinds of sodium licunin sulfonate or the like to improve the dispersion of the magnetic powder.

As the polymer electrolyte, carboxymethyl cellulose,
Maleic anhydride polymer, polyacrylic acid, polymethacrylic acid, alginic acid and other sodium salts, ammonium salts, polyvinylbenzyltrimethylammonium chloride, polyvinylpyridine hydrochloride, etc. can be arbitrarily selected, and glycol ethers can also be used. teeth,
Methyl cellosolve, propyl cellosolve, butyl cellosolve, tetrahydrobilane-methanol, propyl carpitol, ■-butoxyethoxy 2-propatol,
One or two kinds of diacetone alcohol etc. can be used arbitrarily.

The three main components mentioned above have the following blending ratio. In other words, the optimum amount of the polymer substance to be applied is in the range of 0.5 to 7.0 parts per 100 parts of the magnetic powder (same weight of 2 or less), and in the range of 0.2 to 10.0 parts. Glycol ether can also be used as anti-magnetic powder (100 parts)
The range of 1.0 to 3.0 parts is optimal, and it can be applied in the range of 0.5 to 7.5 parts. When either or both of the lower limits, 0.2 parts for the former and 0.5 parts for the latter, fall below the above range, the water-based magnetic composition coating film will be
Regardless of the thickness, desired characteristics such as reading reproduction output, reverse reading reproduction output, and DC noise level cannot be obtained.
In particular, the deterioration of read and playback output characteristics is remarkable. In addition, the amount of the above-mentioned substance applied to the magnetic powder is at its upper limit, that is, 10.0 at the former.
%, the latter being 5.0 parts, or both at the same time, the resulting aqueous magnetic composition coating film will be
Even if the deterioration (deterioration) of each of the above-mentioned characteristics can be avoided as a whole regardless of the thickness, it cannot be said that the desired good characteristics are achieved, and the deterioration (deterioration) of the read and reproduced output characteristics still remains unimproved for practical use. (See Examples and Comparative Examples)
.

However, as long as the above three components have the predetermined compounding ratio (above) and are inseparably interrelated, the resulting aqueous magnetic composition coating film will be a thin film (8 to 12μ).
However, it is a stable composition that simultaneously has the above-mentioned desired properties and is highly practical.

In putting Water-Based Magnetic Composition 1 into practical use, a coating solution of the composition as described below (see Examples) is applied to the surface of a support by a conventional method so that the coating amount after drying is 18.0 to 36.0%. (film thickness 12
~16μ), oriented in a magnetic field, dried, and then subjected to supercalender treatment.

General paper, plastic sheet, etc. are used as the support, and coating can be accomplished using a known air knife coater, roll coater, etc.

Therefore, when the product obtained in this way is used as, for example, a magnetic ticket, a magnetic card, or a magnetic recording tape, it simultaneously has all of the desirable characteristics such as reading playback output, reverse reading playback output, and DC noise level characteristics. This method can overcome the drawbacks of the conventional method (mentioned above), and can be obtained at low cost as a constant and stable product, so it has a wide range of applications in this type of field.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

Example l Solution A: γ-iron oxide (particle size 0.4μ) 100.
0 parts pyrophosphate], Ol water
The mixture of 10Q and 0' was ground in a ball mill for 24 hours.

Mix to obtain a dispersion.

Solution B: Carboxymethyl cellulose sodium salt (
12.5 parts of a 0.8% aqueous solution with an average molecular weight of 80,000) Polyacrylate copolymer latex (solid content 50%) 55.07
A mixture of 0.4 # of propyl seronulp was mixed for 30 minutes using a propeller type stirrer to obtain an emulsion liquid.

Next, liquid B was stirred and mixed with liquid A to obtain a magnetic composition coating liquid.
The coating amount after drying was 18 seams (film thickness 12μ) on one side of the
) and 36 mm (film thickness: 16 μm), oriented in a magnetic field, dried, and supercalendered (smoothness: 55 seconds) to obtain two types of magnetic coated paper.

Example 2 Solution A: Same as Example 1 Solution B: Carboxymethyl cellulose sodium salt (
0.8% aqueous solution (average molecular weight 80,000) 25.0 parts Ethylene-vinyl acetate copolymer latex (solid content 50%) 55.0 #
A mixed solution of 0.5" methyl cellosolve was treated in the same manner as in Example 1 to obtain an emulsion solution.

Next, mix B solution with A solution in the same manner as in Example 1. Example 3 A solution: Same as Example 1 B solution: Carboxymethyl cellulose sodium salt (
1% aqueous solution with average molecular weight 60,000 40.0 parts Vinyl chloride/vinyl acetate copolymer latex (solid content 50%) 55.0
A mixed solution of #Tetrahydropyran 2-methanol 0.7 is treated in the same manner as in Example 1 to obtain an emulsion solution. Next, solution B is mixed with solution A in the same manner as in Example 1 to obtain a magnetic composition coating solution. After obtaining, this was carried out in the same manner as in Example 1 to obtain two kinds of magnetic coated papers.

Example 4 Solution A: Same as Example 1 Solution B: Polyacrylic acid sodium salt (average molecular weight 9
1% aqueous solution of 50.0 parts Acrylonitrile-butadiene copolymer latex (solid content 50%) 55. A mixture of 1.0 # of propylcarpitol was treated in the same manner as in Example 1 to obtain an emulsion liquid.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, and this was then treated in the same manner as in Example 1 to obtain two types of magnetic coated paper.

Example 5 Solution A: Same as Example 1 Solution B: 1% aqueous solution of sodium carboxymethylcellulose (average molecular weight 60,000) 100.0 parts Vinyl chloride/vinyl acetate copolymer latex (solid content 50%) 55. 0#
A mixture of tetrahydropyran-methanol 2.0% was treated in the same manner as in Example 1 to form an emulsion.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, and then kneaded in the same manner as in Example 1 to obtain two types of magnetic coated paper.

Example 6 Solution A: γ iron oxide 100.0 parts Sodium hexametaphosphate 1.51 water
A 100.0 # mixture is treated in the same manner as in Example 1 to obtain a dispersion.

Solution B: A 4.3% aqueous solution of sodium alginate (average molecular weight 80,000) 70.0 parts Vinyl chloride/vinyl acetate copolymer latex (solid content 50%) 55.0 #butyl cellosolve A mixed solution of 3.0% An emulsion liquid is obtained by processing in the same manner as in Example 1.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, and this was then treated in the same manner as in Example 1 to obtain two types of magnetic coated paper.

Example 7 Solution A: Same as Example 1 Solution B: 8% aqueous solution of styrene maleic anhydride copolymer (average molecular weight 6000) 87.5 parts ethylene.
Vinyl acetate copolymer latex (solid content 50%) 55.0 parts Propylcarpitol 3. The ON mixture is treated as in Example 1 to form an emulsion solution.

Next, liquid B was stirred and mixed into liquid A to obtain a magnetic composition coating liquid, and then the same procedure as in Example 1 was carried out.
Two types of magnetic coated papers were obtained.

Example 8 Solution A: Same as Example 1 Solution B: 9% aqueous solution of methylcellulose (average molecular weight 15,000) 1c10.0 parts "vinyl chloride.
Vinyl acetate copolymer latex (solid content 50%) 55.0#tetrahydropyran 2-methanol 5. The mixed solution of ON was treated in the same manner as in Example 1 to obtain an emulsion solution.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, which was then treated in the same manner as in Example 1 to obtain two types of magnetic coated papers.

Example 9 Solution A: Same copolymer latex as in Example 1 (solid content 50%) 55. A mixed solution of O# diacetone alcohol 7.50' was treated in the same manner as in Example 1 to obtain an emulsion liquid.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, which was then treated in the same manner as in Example 1 to obtain two types of magnetic coated papers.

Example 10 Solution A: Same as Example 1 Solution B: Styrene maleic anhydride (average molecular weight 300
0) 15% aqueous solution 73.3 parts Styrene-butadiene copolymer latex (solid content 50%) 55. O# diacetone alcohol 8. The mixture of Ol is treated in the same manner as in Example 1 to obtain an emulsion liquid.

Next, liquid B was mixed with liquid A to obtain a magnetic composition coating liquid in the same manner as in Example 1, and then the same process was repeated as in Example 1 to obtain two types of magnetic coated papers.

Comparative Example I Liquid A: Same combined latex as in Example 1 (solid content 50%) 55. The mixed solution of ON was treated in the same manner as in Example 1 to obtain an emulsion solution.

Next, liquid B was mixed with liquid A in the same manner as in Example 1 to obtain a magnetic composition coating liquid, and this was coated in the same manner as in Example 1 (coating amount 'd6 Vn?: film thickness 16μ). A magnetic coated paper was obtained.

Comparative Example 2 Solution A: Same as Example 1 Solution B: Vinyl chloride/vinyl acetate copolymer latex (solid content 50 inches) 55.0 parts Tetrahydropyran 2-methanol 2. The mixed solution of Ol was treated in the same manner as in Example 1 to form an emulsion solution.

Next, a magnetic composition coating liquid obtained by mixing liquid B with liquid A in the same manner as in Example 1 was applied in the same manner as in Example 1 (coating amount: 36 cm).
A magnetic coated paper was obtained with a film thickness of 6 μm. □ Comparative Example 3 Solution A: Same as Example 1 Solution B: 55.0 parts of vinyl chloride/vinyl acetate copolymer latex (solid content 50%) Mix Solution B with Solution A in the same manner as Example 1. The obtained magnetic composition coating solution was coated in the same manner as in Example (coating amount: 36: film thickness: 16 μm) to obtain magnetic coated paper.

Comparative Example 4 Solution A: Same as Example 1 Solution B: Carboxymethyl cellulose ammonium salt (1.3% aqueous solution with average molecular weight 5 (5) 100.0 parts Ethylene-vinyl acetate copolymer latex (solid content 50%) 55 .0
The mixed solution # is treated in the same manner as in Example 1 to obtain an emulsion solution.

Next, a magnetic composition coating liquid obtained by mixing liquid B and liquid A in the same manner as in Example 1 was applied in the same manner as in Example 1 (coating amount J6 Vr
ri': film thickness 16μ) to obtain magnetic coated paper.

The properties of the magnetic coated papers obtained in Examples (1 to 10) and Comparative Examples (1 to 4) were investigated, and the results shown in the following table were obtained.

(Additional notes) (1) The film thickness is calculated when the magnetic composition coating liquid is applied separately to one side of the support (consistent 157 sheets of high-quality paper) so that the coated amount after drying is 18 sheets and 469 sheets/yl. This is an actual measured value.

(2) The 0 in the polymer electrolyte indicates the average degree of polymerization (unit: nig.) of the same substance.

(3) Indicates the coated paper characteristics: A: reading playback output, B: back reading playback output, C: DC noise level, each value is for automatic ticket vending machines and automatic ticket gates (manufactured by Fusei Electric Co., Ltd.). (manufactured by Hitachi Electronics Co., Ltd.) are respectively connected and measured.

(4) Evaluation was indicated by the symbols ◎Good, 0 Fair, and ΔPoor.

As is clear from the table above, this invention provides that when the three main components of magnetic powder, polymer electrolyte, and glycol ether form a specific correlation (weight ratio) under certain conditions,
The thickness of the coating film (versus the support) of the composition of the present invention is from 40 to
It can be seen that even if it is less than 70%, the above-mentioned intended purpose can be achieved and the desired effect can be immediately exhibited, and moreover, it can be provided at a low cost.

Claims (1)

[Claims] In a water-based magnetic coating composition comprising a magnetic agent powder and a binder, the aqueous coating composition comprises a magnetic side powder, a polymer electrolyte, and a glycol ether, and the polymer electrolyte contains a countermagnetic agent powder of 0. 2 to 10.0 parts by weight of glycol ether and 0.5 to 5.0 parts by weight of antimagnetic agent powder.