JP2002324309A - Calender - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unevenly formed part on a sheet in the width direction. SOLUTION: A magnetic recording medium passes between a heater roll and an adjusting roll 12 and is pressed. The adjusting roll 12 consists of a support 18 and an outer cover 19. Two spiral grooves 22 and 23 are provided on the outer surface of the support 18. A heating medium 20 is made to flow in the spiral grooves 22 and 23. Thus, the outer cover 19 has less uneven deformation due to thermal heat expansion, and it can press the magnetic recording medium more uniformly than before.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calender for pressing a sheet material such as a magnetic recording medium between at least a pair of metal rolls.

[0002]

2. Description of the Related Art Magnetic recording media such as magnetic tapes and magnetic disks are used in audio, video, cameras, computers and the like. In this magnetic recording medium, a magnetic layer is formed on a sheet-like support, and calendering is performed for the purpose of smoothing the surface of the magnetic layer and improving the filling degree. When the calendering process is performed, the packing density of the magnetic layer is increased and the performance of the magnetic recording medium is improved, and the surface of the magnetic recording medium is mirror-finished to reduce dropouts.

Conventionally, as a method of calendering, a method has been generally used in which a magnetic recording medium is pressed between a heat generating roll, which is a metal roll provided with a heat generating mechanism, and an elastic roll. According to this method, even if there is a dimensional error in the longitudinal direction of the heat generating roll, the elastic roll is elastically deformed and absorbs the error. It is possible to reduce the molding distribution difference.

However, recently, due to the demand for higher density of the magnetic layer, a magnetic recording medium is applied at a higher pressure than the conventional method as proposed in, for example, JP-A-6-162495. Pressing calendaring methods are being used. In the method disclosed in JP-A-6-162495, a magnetic recording medium is pressed and heated using a heating roll and a non-heating roll formed of metal. According to this, when a magnetic recording medium is pressed using a pair of metal rolls, a difference in molding distribution in the width direction of the magnetic recording medium increases due to a dimensional error in a longitudinal direction of each outer peripheral surface. By forming the precision of the outer peripheral surface of the metal roll in the longitudinal direction with high precision, the magnetic recording medium is pressed with a uniform pressure. Then, since the magnetic recording medium is pressed between the metal rollers and pressed, a sufficient pressure can be obtained at the time of pressing, and a good effect of the calendar processing can be obtained.

[0005]

However, in the method disclosed in Japanese Patent Application Laid-Open No. 6-162495, the non-heating roll and the heating roll exchange heat, and the non-heating roll and the non-heating roll are deformed by thermal expansion. In this case, since both ends in the longitudinal direction of the non-heating roll have a large area that comes into contact with the outside air, the temperature decreases from the center to both ends, so that the non-heating roll has a uniform temperature distribution in the longitudinal direction. However, with this, the deformation due to thermal expansion is biased. Therefore, it is impossible to uniformly contact the outer peripheral surfaces of the heat generating roll and the non-heat generating roll, and the magnetic recording medium may not be pressed with a uniform pressure in the width direction. As a result, the difference in molding distribution in the width direction of the magnetic recording medium subjected to calendering increases, and when the magnetic recording medium after calendar processing is processed into product units, not only quality differences occur in each product but also defective products occur. There is a problem that productivity is reduced and manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when a sheet is passed through at least a pair of metal rolls and pressed, the difference in molding distribution in the width direction of the sheet is reduced. In addition, it is an object of the present invention to provide a calendar device in which the deformation due to the above-mentioned thermal expansion is improved and the quality of the sheet is prevented from being affected.

[0007]

In order to achieve the above object, a calendar device according to the present invention is directed to a calendar device for passing a sheet-like material between at least a pair of metal rolls and pressurizing the sheet-like material. Is a heat generating roll provided with a heat generating mechanism, and the other uses an adjusting roll provided with a passage for passing a heat medium therein so as to make the surface temperature distribution uniform.

When the sheet-like material is used as a magnetic recording medium, it is effective for improving the surface smoothness and the packing density of the magnetic layer. Further, the passage is provided in the vicinity of the outer peripheral surface inside the adjustment roll, the passage is at least one spiral passage provided spirally along the center axis direction of the adjustment roll,
The distance between the spiral passage and the outer peripheral surface of the adjusting roll is 20 m.
m and 100 mm or less. In addition, it is preferable from the viewpoint of quality that the distribution obtained by the above-mentioned configuration is within 2 ° C.

[0009]

FIG. 1 is a schematic side view showing a main part of a calendar device 10 embodying the present invention. The calendar device 10 includes heating rolls 11a and 11b, an adjusting roll 12, and guide rolls 13a, 13b and 13c. The heating rolls 11a and 11b and the adjusting roll 12 are driven by a drive mechanism (not shown), and are indicated by arrows in the drawing. To rotate. The guide rolls 13a, 13b, 13c are provided near the heat generating rolls 11a, 11b and the adjustment roll 12, and are provided rotatably. Then, the magnetic recording medium 14 is passed between the heat generating rolls 11a, 11b and the adjusting roll 12 and is pressed while the direction is changed by the guide rolls 13a, 13b, 13c.

The heat generating rolls 11a and 11b are provided with a heat generating mechanism 15 such as an electric heating coil inside, and the temperature of the outer peripheral surface can be adjusted by controlling the heat generating mechanism 15. In the present embodiment, the outer peripheral surface temperatures of the heat generating rolls 11a and 11b can be adjusted between 80 and 100 ° C. The heating roll 1
The temperature of the outer peripheral surfaces of 1a and 11b is not limited to 80 to 100 ° C., but is preferably adjusted to an appropriate temperature.

FIG. 2 is a cross-sectional view showing the structure of the adjusting roll 12, and FIG. 3 is a perspective view. The arrows in FIG. 2 indicate the direction in which the heat medium flows. The adjustment roll 12 includes a support shaft 18 and an exterior member 19. The support shaft 18 is formed in a substantially cylindrical shape, and both ends thereof are pivotally supported to be rotatable. The exterior member 19 is formed in a substantially cylindrical shape, and the support shaft 18 is inserted through a hollow portion thereof. Then, the exterior member 19 rotates integrally with the support shaft 18, and the outer peripheral surface contacts the magnetic recording medium 14.

The support shaft 18 is provided with a supply passage 21 for flowing the heat medium 20, two spiral passages 22, 23, and a discharge passage 24. The supply passage 21 is provided on the support shaft 18.
The heat medium 20 is supplied to the spiral passages 22 and 23, and is hollowed out from the end face of the support shaft 18 in a cylindrical shape so that the center axis of the support shaft 18 is the same as that of the support shaft 18. The end portion branches in two directions. Each part of the supply passage 21 branched in two directions is connected to the support shaft 18.
Are connected to the spiral passages 22 and 23 on the outer peripheral surface of the spiral passage 22. As a result, the heat medium 20 supplied to the adjustment roll 12 passes through the supply passage 21 and branches in two directions to form the spiral passage 22,
Flow to 23.

The spiral passages 22 and 23 are provided in a groove shape on the outer peripheral surface of the support shaft 18, and draw spirals in opposite directions so that they do not cross each other.
It is arranged for a certain distance. And the support shaft 18
The spiral passages 22, 23 forming portion is covered by the exterior member 19, and the heat medium 20 flowing through the spiral passages 22, 23.
Are designed not to leak out of the adjustment roll 12. Further, the spiral passages 22 and 23 are arranged at a distance of 40 mm from the outer peripheral surface of the exterior member 19. The end portions of the spiral passages 22 and 23 are respectively connected to the discharge passage 24, and the heat medium 20 that has passed through the spiral passages 22 and 23.
Flows through the discharge passage 24.

The discharge passage 24 is provided in the same manner as the supply passage 21. The discharge passage 24 is formed in a cylindrical shape from the end face of the support shaft 18 so that the center axis of the support shaft 18 becomes the same as that of the support shaft 18. Has branched to. Each portion of the discharge passage 24 branched in two directions is connected to the spiral passages 22 and 23 on the outer peripheral surface of the support shaft 18. Spiral passage 22,
When the heat medium 20 that has passed through 23 flows into the discharge passage 24, the heat medium 20 joins from two directions and is discharged to the outside of the adjustment roll 12. Note that the spiral passages 22 and 23 are preferably arranged at a position of 20 mm or more and 100 mm or less from the outer peripheral surface of the adjustment roll 12. The outer peripheral surface temperature of the adjusting roll is 2
The temperature is preferably set to 0 ° C to 50 ° C.

In the present embodiment, water is used as the heat medium 20, and the temperature of the outer peripheral surface of the adjusting roll 12 is adjusted in the range of 20 ° C. to 50 ° C. by flowing cooling water through the spiral passages 22 and 23. Is done. Normally, the adjusting roll 12 receives heat from the heat generating roll 11 via the magnetic recording medium 14 and is generally cooled.
If the amounts of heat of a and 11b are insufficient, the heat medium 20 may be heated and used. Further, the heat medium flowing through the adjustment roll 12 is not limited to water, but is preferably used as appropriate according to a desired temperature, such as oil or alcohol.
Further, in the present embodiment, the heat medium 20 is supplied to the spiral passage 22,
Although the flow is made to flow from the same direction to the flow path 23, the flow is not limited to this, and the flow may be made to flow to one of the spiral passages 22 and 23 from one direction and flow to the other from the opposite direction opposite to the one direction.

FIG. 4 is an enlarged view of a portion A in FIG. The magnetic recording medium 14 includes a sheet-like support 28, a non-magnetic layer 29, a magnetic layer 30, and a back coat layer 31. The sheet-like support 28 is formed of, for example, polyethylene terephthalate (PET), and one surface thereof has:
A nonmagnetic layer 29 is formed, and a magnetic layer 30 is formed above the nonmagnetic layer 29. A back coat layer 31 is formed on the opposite side of the sheet-like support 28 from the one surface. The magnetic recording medium 14 includes the non-magnetic layer 29 and the magnetic layer 3
The surface on which 0 is formed contacts the heat generating rolls 11a and 11b,
The paper is passed between the heat generating rolls 11 a and 11 b and the adjustment roll 12 so that the surface on which the back coat layer 31 is formed contacts the adjustment roll 12.

[0017]

Next, specific examples of the composition and manufacturing method of the magnetic recording medium 14 and a calendering method suitable for the magnetic recording medium 14 will be described.

(1) Preparation of coating solution for forming nonmagnetic layer and coating solution for forming magnetic layer a. Composition of dispersion liquid containing abrasives α-Al ₂ O ₃ (alumina) 100 parts (parts by weight) Polar group (—SO ₃ Na group) -containing vinyl chloride copolymer 12 parts Methyl ethyl ketone 100 parts To prepare a dispersion containing an abrasive.

B. Non-magnetic layer forming component Non-magnetic layer powder Titanium dioxide TiO ₂ (rutile type) 100 parts Magnetic substance surface treatment agent 0.3 parts Polar group (-SO ₃ Na group) -containing vinyl chloride copolymer 12 parts Polar group ( -SO ₃ Na group-containing polyester polyurethane resin 5 parts Polyisocyanate 3 parts Dispersion solution containing the above-mentioned abrasive (α-alumina) 10 parts Carbon black 10 parts Butyl stearate 0.1 parts Stearic acid 0.2 parts Oleic acid 0.1 parts Methyl ethyl ketone 150 parts Cyclohexanone 150 parts c. Magnetic layer forming components ferromagnetic metal powder 100 parts magnetic surface treating agent 0.3 parts polar group (-SO ₃ Na group) containing vinyl chloride copolymer 10 parts polar group (-SO ₃ Na group) containing polyester polyurethane resin 2.5 parts Polyisocyanate 2.5 parts Dispersion containing the above abrasive (α-alumina) 10 parts Carbon black 1 part Butyl stearate 1 part Stearic acid 2 parts Oleic acid 1 part Methyl ethyl ketone 150 parts Cyclohexanone 50 parts Among the components for forming the magnetic layer and the components for forming the non-magnetic layer, each component other than the dispersion containing the abrasive is kneaded with a continuous kneader (open kneader), and the coating solution for forming the non-magnetic layer and the coating for forming the magnetic layer. Each liquid was adjusted.

(2) Preparation of coating solution for forming back coat layer (Component for forming back coat layer) Fine carbon black powder 100 parts Coarse carbon black powder 10 parts Calcium carbonate (soft inorganic powder) 80 parts α-alumina (Hard inorganic powder) 5 parts Nitrocellulose resin 140 parts Polyurethane resin 15 parts Polyisocyanate 40 parts Polyester resin 5 parts Dispersion solution: Copper oleate 5 parts Copper phthalocyanine 5 parts Barium sulfate 5 parts Methyl ethyl ketone 2200 parts Butyl acetate 300 parts Toluene 600 parts After the respective components for forming the back coat layer were kneaded with a continuous kneader, a coating solution for forming a back coat layer was prepared.

(3) Preparation of magnetic recording medium The obtained non-magnetic coating liquid and the magnetic layer-forming coating liquid are mixed with each other so that the dried non-magnetic layer has a thickness of 2.2 μm. The thickness of the dried magnetic layer is 0.3 μm
Long polyethylene terephthalate (P
ET) A simultaneous multilayer coating was performed on a support (thickness: 6.0 μm) 28. And while both layers are still wet, a cobalt magnet with a flux density of 3000 Gauss and 1
The alignment treatment was performed using a solenoid having a magnetic flux density of 500 Gauss. Thereafter, drying was performed to provide the nonmagnetic layer 26 and the magnetic layer 27.

Then, the other side of the support 28 (the magnetic layer 2
7), the above-mentioned coating liquid for forming a back coat layer is applied so that the thickness after drying becomes 0.5 μm, and dried to form a back coat layer 31, and one surface of the support 28 is provided. A magnetic recording medium 14 provided with a non-magnetic layer 29 and a magnetic layer 30 and a back coat layer 31 on the other surface.
I got

Next, the heat generating rolls 11a, 11
The magnetic recording medium was calendered using b and the adjusting roll 12, and the molding distribution difference and quality of the magnetic recording tape formed by this were measured. Measurement of molding distribution difference
The surface glossiness of the magnetic recording tape is measured by measuring the surface glossiness of the magnetic recording tape as a substitute value of the molding distribution difference, and the distribution (maximum value-minimum value) of the surface glossiness in the width direction (VG2 manufactured by Nippon Denshoku Industries Co., Ltd.)
000). The quality was measured using a magnetic recording / reproducing system, and the output was measured with the output of a standard tape (a tape using a ferromagnetic metal powder as a magnetic material) being 100%. If the output does not exceed the reference value of 85% or more, the tape becomes defective. In addition, the output was measured at a place where molding property was poor (low gloss value). The calendar processing conditions are as shown below.

Calendering conditions Pressure = 3920 N / cm Speed = 150 m / min Heating metal roll temperature = 90 ° C. While controlling the temperature of the outer peripheral surface of the heat generating rolls 11a and 11b shown in FIG. 10 tapes
000 m, and the results are shown in Table 1. In addition, the temperature distribution difference indicates the temperature distribution difference (maximum value−minimum value) in the longitudinal direction of the outer peripheral surface of the adjustment roll 12, and Examples 1-1 and 1--1.
2 is a result of adjusting the amount of the heat medium 20 (water) so as to minimize the temperature distribution difference and comparing the results. In the evaluation, ○ indicates that the quality of the processed tape is good, and X indicates that the tape is defective.

Comparative Example 1 The same evaluation as in Example 1 was conducted except that a metal roll having no passage for the heat medium 20 was used instead of the adjusting roll 12 as a non-heating roll.

Comparative Example 2 An adjusting roll 35 shown in FIG. 5 was used instead of the adjusting roll 12 as a non-heating roll. A passage 36 through which the heat medium 20 flows is provided in the adjusting roll 35 in a cylindrical shape from one end surface to the other end surface, and the central axis of the passage 36 and the central axis of the adjusting roll 35 are the same. And
The evaluation was performed in the same manner as in the example except that the adjusting roll 35 was used. The temperature distribution difference indicates the temperature distribution difference (maximum value-minimum value) on the outer circumferential surface of the adjustment roll 35 in the longitudinal direction. Are adjusted to minimize the temperature distribution difference, and compared.

[0027]

[Table 1]

As shown in Table 1 above, Comparative Examples 1 and 2-
In 1-2 and 1-2, the temperature distribution difference of the non-heating roll is:
As the molding distribution difference increased, the output was all less than 85% of the reference value, and the tape quality was all poor. Further, the temperature distribution difference between these non-heating rolls is all 2 ° C. or more. On the other hand, Embodiment 1 of the present invention
In the cases of -1 and 1-2, the difference in molding distribution of the adjustment roll 12 became small, the output became 85% or more of the reference value, and both tape qualities were good. Further, the temperature distribution difference between the adjustment rolls 12 was within 2 ° C. in both cases.

From these results, it is possible to press the tape with a uniform force as compared with the conventional one by setting the temperature distribution of the non-heating roll within 2 ° C., thereby forming the tape in the width direction. It was confirmed that a high quality tape could be obtained by reducing the distribution difference.

[0030]

As described above, according to the calendar device of the present invention, one of the pair of metal rolls is provided with a heating mechanism provided with a heating mechanism, and the other is provided with a heat inside so as to make the surface temperature distribution uniform. Since the adjusting roll is provided with a passage for passing the medium, the sheet-like material such as a magnetic recording medium can be pressed with a uniform pressure to prevent the quality of the sheet-like material from being affected.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a calendar device embodying the present invention.

FIG. 2 is a longitudinal sectional view showing a configuration of an adjustment roll.

FIG. 3 is a perspective view illustrating a configuration of an adjustment roll.

FIG. 4 is an enlarged view of a portion A in FIG. 1;

FIG. 5 is a front view schematically showing a metal roll used in Comparative Example 2.

[Explanation of symbols]

 11a, 11b Heating roll 12 Adjusting roll 14 Magnetic recording medium 15 Heating mechanism 22, 23 Spiral passage

Claims (1)

[Claims] 1. A calendar device for applying a pressure by passing a sheet between at least a pair of metal rolls, wherein one of the pair of metal rolls has a heat generating roll provided with a heat generating mechanism, and the other has a uniform surface temperature distribution. Thus, the calender device is an adjusting roll having a passage through which a heat medium passes.