JPS5971133A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good orientation properties (square ratio) and an excellent display property after orientation by making the intensity of a magnetic field increasingly smaller toward the rear stage and performing successively drying from the initial stage. CONSTITUTION:A substrate 1 provided thereon with an undried magnetic liquid coating layer 2 is continuously run over a pass roll 3 in an arrow direction and is subjected to orienting and drying in an orienting section and drying section. The orienting section in this embodiment is divided to front orienting sections 4, 5 and rear orienting sections 6, 7, and drying sections 8, 9 are provided between both. The magnetic field in the sections 6, 7 is set smaller than the magnetic field in the sections 4, 5. The layer 2 in an undried state is oriented in the sections 4, 5. Dry air is blown onto the coated layer in the drying section and while the layer is dried, the layer is oriented in the rear orienting sections. The drying section consists of, for example, an air feed duct 8 and an evacuation duct 9, and cold air and the warm air higher than a room temp. is fed through the duct 8 onto the coated film, thereby removing partly the solvent in the coating liquid. The condition under which the coated film is prevented from drying at just before the substrate enters the rear orienting sections is selected according to the formulation of the coating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium 4). In particular, the present invention relates to a method for manufacturing a magnetic recording medium with improved orientation (squareness ratio) and excellent surface properties after a 1.1-zip direction.

Magnetic arrangement/di-body (audio tape, video tape, etc.)
In order to improve the properties of the m-type layer, it is extremely important to improve the orientation of the m-type layer and to improve the surface properties! II is essential. For orientation, a common method is to apply a magnetic coating solution to a support using a brass cloth, and then perform magnetic orientation using a magnetic field generated by a solenoid, a permanent magnet, or a combination of the two in an undried state before drying. .

(For example, Japanese Patent Publication No. 34-2536, U.S. Patent No. 3,
001,891). It is also known to dry the magnetic coating liquid while orienting it after coating. (For example, see Japanese Patent Application Laid-Open No. 141612/1983). However, in the former method, drying is performed after orientation, which causes disturbances in the once oriented magnetic material and defects that reduce the orientation (squareness ratio).Also, in the latter method, although the orientation property is improved, there are defects after drying. There was a drawback that streaks were likely to appear on the surface of the film, impairing the surface properties.

Furthermore, for good magnetic field orientation row 5.

Although the formulation and dispersibility of the 18g coating solution are important, a high magnetic field is generally used. (In this case, a high magnetic field means a magnetic field that is higher than the coercive force of the magnetic material in the coating liquid used.) When the coating liquid (layer) is oriented for a long time in a high magnetic field, the squareness ratio is good (
However, on the other hand, the magnetic material aggregates, and the surface quality Y of the flat surface deteriorates. Such a tilt becomes more frequent as the size of the magnetic material becomes smaller.

The present invention has been developed through various studies to solve such problems.
As a result of repeated efforts, the method of the present invention described below has achieved its purpose.
I was able to achieve this.

In other words, the present invention provides a magnetic recording medium that comprises applying a magnetic coating liquid to a support, orienting it, and drying it.
In the construction method, the orientation part is divided into at least a front part and a rear part, and the strength of the magnetic field in the rear part is determined! The strength of the magnetic field is smaller than that in the front part, and the magnetic coating solution that has not been applied onto the support is oriented in a wet or partially dried state in the orientation part of the front part, and then dried to a semi-dry state. A method for producing an ifN air recording medium, which comprises orienting it in a rear orientation section while drying or semi-dry F3KE, and completing the drying after leaving the rear orientation section or rear orientation 1 $. It is.

The present invention will be described in detail below with reference to the accompanying drawings.

Note: 1. Abrasive materials and additives used in the present invention.

There are no particular limitations on the solvent, the composition of the rupturable coating solution, the support, the coating method, etc. 1. General magnetic recording as described in Japanese Patent Publication No. 32-408804, etc. All the techniques used for J construction (of jj bodies) can be used in the uA of the present invention.

After applying the magnetic coating liquid to the support by a suitable coating means, orientation and drying are carried out according to the method of the present invention as follows.

FIG. 1 shows 171 of the apparatus used to carry out the present invention.
Mr! In this explanation, a support 1 provided with an undried magnetic coating liquid coating layer 2 is continuously run on a pass roll 3 in the direction of the arrow, and is oriented and dried in an orientation section and a drying section. In this embodiment, the orientation section is divided into a front orientation section 4.5, a rear orientation section 6.7, and a drying section 8.9 between the two.
This is provided. The magnetic field of the rear orientation section 6.7 is similar to that of the front orientation section 4.
The magnetic field is set to be smaller than the magnetic field of 5°. The strength of the magnetic field in the orientation section is preferably larger than the coercive force (He) of the sum of '6'4't p'r471' in the tube cloth liquid.

The coating layer 2 is oriented in a pre-stage orientation section 4.5 while not being dried. Next, a drying air is applied to the V-coated layer in a drying section, and while drying, the layer is oriented in an orientation section at the rear.

In this example, the drying section consists of an air supply duct 8 and an exhaust duct 9, and as a drying means, cold air or warm air higher than room temperature is sent from the air supply duct 8 and applied to the coating film.

Remove 1 part of the solvent from the coating solution. However, conditions are selected in accordance with the formulation of the coating liquid so that the coating film does not become a soft film (a completely dried film) immediately before entering the rear alignment section, that is, it is in a semi-dry state.

In addition, in this embodiment, a method of drying after exiting the front alignment section was exemplified, but if necessary, the front section ^[
Part of the solvent may be removed by drying a part of the product in a commercial location.

In this way, the semi-dry coating film is sent to the rear orientation section.

At this time, the strength of the rear orientation part magnetic field is as described in 5 above.
Make it smaller than the strength of the magnetic field in the front half. After that, back 1F
ii" Dry in the white part from the necessary trap. Drying may be performed in a magnetic field until it becomes a buffy coat (dry slightly in a rear magnetic field, rear orientationff! The following results can be obtained by using such a method and apparatus.

That is, in the front orientation part, the coating film still contains solvent and the viscosity is reduced, so it is easy to orient the A material.

If drying is continued in this front orientation section, the orientation will be poor, but as mentioned above, the magnetic field will cause agglomeration and deteriorate the surface properties. On the other hand, if the material is left in the orientation area without being dried, no magnetic field is applied until the material is dried, resulting in the once oriented magnetic material being disturbed and its orientation worsening. The present inventors have shown a method for improving this. In other words, since the magnetic material is oriented after leaving the front orientation section, this state is maintained by drying in a small magnetic field that does not shift or deteriorate the surface properties.

A coating film with good surface properties and orientation can be obtained by such a method. Such an effect is particularly noticeable as the size of the magnetic material becomes smaller. Although it depends on the prescription, such a size is 25 to 30 m2/f according to the size 9 BET method specific surface area.
That's all.

In addition, when using 2[FitJjV as exemplified above, the strength of the front magnetic field is preferably larger than the magnetic material used 1 - magnetic force Hc, and if it is smaller than this, the orientation deteriorates. Furthermore, if the strength of the front magnetic field is too large, the interfacial properties will be poor. A particularly preferable strength is about 1 to 6 times the He of the magnetic material.

Further, as described above, the strength of the rear magnetic field needs to be smaller than the front magnetic field, and if it is stronger than the front magnetic field, the surface quality will deteriorate. The preferred range of the strength of the rear magnetic field Q) is 1/1° to 1/2 of the He of the magnetic material, or 0.1 to 0.5 times the strength of the front magnetic field. (Example above) In , the orienting magnetic field was set before b15. However, in the present invention, three or more stages may be provided as a multi-stage orientation zone, and a drying section may be provided if necessary. However, it is necessary to make the fiB field smaller in the later stages than in the earlier stages.

Furthermore, the drying can be performed in multiple stages with the orientation Y3ff1 or higher, and the strength of the a field can be made smaller, and the drying can be carried out sequentially from the initial stage.

The present invention will be explained below by way of example.

Example The following condition tests were conducted.

(1) Size of the magnetic material used (Go-added Fed) CBET method specific surface area) A 18m2/9 Magnetic material He 3000eB23
y#450#C25#
t5501D30 1#
650#121 Note Inder prescription A Coating liquid composition) B Coating liquid composition β) (31 Strength of front and rear magnetic fields Strength of front magnetic field Strength of rear magnetic field Strength of Pf4/Magnetic material for inner Hc) (Same as left)A
O (none) 0 (none)
B 10 2
C71,0 D6 0.
6E 3 0
．． 5F 2
0. IG 1
0.05H0,8 The front and rear magnetic fields are generated by solenoids.

The effective length is 15 cx each (coating liquid composition) - Magnetic material --- 300 parts (by weight) - Polyester polyol (*) --- 15 # - Soybean lecithin -m-11 - Silicone T-mount (
dimethyl-polysiloxane) ---15#・
Polyisocyanate (3 molar 2,4 l solution)
---30#-Methyl ethyl ketone ---900te Toluene
---300#・Carbon (average particle size 60mμ) ---30#・Chromium oxide <
10.2μ) ---5y* 1 mol of adipic acid, 1 mol of diethylene glycol, and 0.
06 mole reaction product viscosity #(75C) 1000 cp
, Specific gravity: 118 OH value: 60 eM value < 20 Coating liquid composition: IB+ +1T? -Material---300(]・IN)
part reaction product) ---18,
5IDE-241-70) ---
12,4#-Silicone Y mountain (dimethyl polysiloxane) ---0,2# ethyl acetate bath solution) ---12,6#-acetic acid/tyl ---450# methyl ethyl ketone ---6001 (4) Polyethylene terephthalate (PET) with a thickness of 14.5 microns was used for the base, and a coating film was applied to a thickness of 45 microns using a doctor coating method.

The coating speed F was 30 m/min.

(5) The drying conditions in the middle of the solenoid were as follows.

A Inui 9/! Don't do it.

B: A condition in which the line does not change completely when it exits the second half of the orientation section (80C3m/5ec) when drying air is applied (80C3m/5ec).
0U 6m/5ec) The characteristics of the obtained sample after coating were measured by the following method.

(11 Tape squareness ratio vsht Y is used to stop it from Br/8m. Only thicker than i[i direction t<-tv.

+21 Tape Surface Roughness The surface roughness of the magnetic tape was measured as follows. That is, using a surfcom type 3 surface roughness measurement device manufactured by Tokyo Seimitsu Co., Ltd., the cutoff was 0.811JTh.
The surface roughness was measured at a feeding speed of 0.3 m/see'''C.The surface roughness (Ra) was expressed as the average roughness of the center line (unit: 11).

The obtained results are shown in Table 1 along with the viscosity evaluation.

The criteria for overall judgment are shown in Table 1.

Table 1 (Criteria for overall judgment) From the above results, the following can be concluded.

(11) Good surface properties and orientation cannot be obtained using conventional orientation conditions and methods.

(21) The problem of +11 can be solved by dividing the orientation magnetic field into the front and rear parts using the method of the present invention.

(Mountain) In the case of the present invention, the strength of the magnetic field is effective if it is in the range of 1 to 6 times the coercive force of the toilet magnetic material in the front half, particularly preferably in the range of 1 to 3 times the coercive force of the toilet magnetic material, depending on the tape surface properties and squareness ratio. A remarkable effect can be obtained by combining it with O1 to 0.5 times the magnetic field.

(4) Furthermore, such an effect becomes more pronounced as the size of the magnetic material becomes smaller.

(5; The present invention is effective even if the binder formulation is changed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one example of an apparatus for carrying out the present invention. 1--1 support 2--1 abrasive layer 3--1 feed roll 4.5--1 front magnetic field 6.7--rear magnetic field 8--11 dry air feed duct) 9--i Air duct procedure amendment document 1982/S/Mon/1980 Case indication Patent application No. 180510 of 1982 2 Name of the invention Method for manufacturing magnetic recording media 3 Person making the amendment Relationship to the case Name of the applicant for the patent (520) Fuji Photo Film Co., Ltd. Kasumigaseki Building Post Office P.O. Box No. 49 7 Target of amendment "Detailed description of the invention" column 8 and content of amendment "Detailed description of the invention" column are amended as follows. . 1) On page 6, line 10 of the specification, "tilt wa" is amended to "tendency wa". 2) Page 6, line 12, ``The present invention, etc.''
and correct it. 6) On page 5, line 5 of the same, amend ``In addition, the distribution capital'' to ``1, furthermore, the said distribution capital''. 4) On page 8, line 11, correct rFeOJ to 6 r Fe Ox (X < X < n). 5) Correct "45μ" on page 111, line 10 to "4.5μ". that's all

Claims (1)

[Claims] +11 In a method for producing an i-air recording medium, which comprises applying a magnetic coating liquid to a support, orienting it and drying it,
The orientation part is divided into a front part and a ridge part, the strength of the magnetic field in the rear part is made smaller than the strength of the magnetic field in the front part, and the magnetic coating liquid applied on the support is applied to the orientation part in the front part. Orientation in an undried or partially dried state, followed by drying to a semi-dry state, or orientation in a rear orientation part while drying in a semi-dry state, a rear orientation part or a rear orientation. A method for producing a magnetic recording medium characterized by drying the medium after leaving the chamber.
The method for manufacturing a magnetic recording medium according to claim 1, which is 6 times as large. (31 The strength of the rear magnetic field is 1/ of the coercive force of the magnetic material used.
10 to 1/, the method for producing a magnetic recording material according to claim 1.