JP2010086594A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium, which efficiently manufactures the magnetic recording medium with excellent surface smoothness. <P>SOLUTION: A web W with a magnetic layer 12 formed on one surface thereof is nipped using a pair of calender rolls 16 and 18. A web tension at a nip exit E along a conveying direction is set within a predetermined range, and the web W is wrapped on the calender roll 16 on a magnetic layer side at a wrap angle θ within a range larger than 0° and smaller than 180° from the nip exit E. By this means, it is possible to obtain a smooth magnetic layer by nipping the magnetic layer 12 at the calender rolls 16 and 18 and perform calendering stably without interruption. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a magnetic recording medium in which a web having a magnetic layer formed on one side is nipped by a calendar roll.

  A magnetic recording medium such as a magnetic tape having a magnetic layer formed on one side of a support is frequently used. When manufacturing such a magnetic recording medium, the surface of the magnetic recording medium is often smoothed by calendaring.

Conventionally, this surface smoothing technology has been improved. Improvement of smoothing technology by high temperature, high pressure and low speed treatment, improvement of smoothing technology by improving roll surface, improvement of smoothing technology by improving roll material. Are generally known (see, for example, Patent Documents 1 and 2). In addition to these, there are disclosed improvements in smoothness by devising the time until calendar processing, the humidity environment in the calendar processing step, the binder configuration of the medium to be calendared, and the like.
Japanese Patent Application Laid-Open No. 61-192026 JP 2001-31816 A

  However, in recent years, it has been required to efficiently produce a good magnetic recording medium having a high surface smoothness.

  In view of the above fact, an object of the present invention is to provide a method of manufacturing a magnetic recording medium that can efficiently manufacture a good magnetic recording medium having excellent surface smoothness.

  The invention described in claim 1 is a method of manufacturing a magnetic recording medium, wherein a web having a magnetic layer formed on one side is nipped with a calender roll, and a web tension along a conveying direction at a nip outlet is predetermined. Within the range, the web is wrapped on the calender roll on the magnetic layer side at a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet.

  The web tension along the conveying direction at the nip outlet is a web tension in a direction perpendicular to the rotation axis direction of the calendar roll at the nip outlet.

  When the wrap angle is 0 ° or less, the surface of the magnetic layer does not follow the calender roll and the web is pushed out from the nip outlet, so that the effect of smoothing the surface of the magnetic layer cannot be obtained. On the other hand, if it is 180 ° or more, wrinkles are easily formed in the magnetic layer, and handling becomes difficult.

  In the first aspect of the present invention, the web tension along the conveyance direction at the nip outlet is within a predetermined range and the wrap angle from the nip outlet is within the above range. A recording medium can be obtained efficiently. The wrap angle is preferably 2 ° or more and less than 30 °.

  According to a second aspect of the present invention, there is provided a magnetic recording medium manufacturing method comprising a step of continuously niping a web having a magnetic layer formed on one side thereof with a calender roll two or more times, wherein the nip outlet is at least in the latter half of the nip. The web tension along the conveying direction is set within a predetermined range, and the web is wrapped on a calender roll on the magnetic layer side at a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet.

  When the magnetic recording medium is nipped twice or more consecutively by the calender roll, the smoothing of the surface of the magnetic layer is more likely to be hindered at the nip exit in the latter nip than in the first nip. Therefore, according to the second aspect of the present invention, even when the magnetic recording medium is nipped by the calender roll continuously twice or more, a good magnetic recording medium having excellent surface smoothness can be efficiently produced.

  The invention according to claim 3 is a method for manufacturing a magnetic recording medium, wherein a step of continuously niping a web having a magnetic layer formed on one side thereof with a calender roll at least twice is provided, wherein at least the web has a maximum pressure. The web tension along the conveying direction at the nip outlet in the receiving nip is within a predetermined range, and the web is applied to the calender roll on the magnetic layer side with a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet. Wrap.

  When the magnetic recording medium is nipped twice or more times continuously with a calender roll, the surface smoothing of the magnetic layer tends to be hindered at the nip exit of the nip where the web receives the maximum pressure. Therefore, according to the third aspect of the present invention, even if the magnetic recording medium is nipped with a calender roll continuously twice or more, a good magnetic recording medium having excellent surface smoothness can be efficiently produced.

  The invention according to claim 4 is a method of manufacturing a magnetic recording medium, wherein a step of continuously niping a web having a magnetic layer formed on one side thereof with a calender roll at least twice is provided, wherein at least the web has a maximum pressure. The web tension along the conveyance direction at the nip outlet in the nip to be received and the nip after that is within a predetermined range, and at the lap angle in the range larger than 0 ° and smaller than 180 ° from the nip outlet The web is wrapped in a calendar roll.

  According to the invention of the fourth aspect, the effect of the invention of the third aspect can be more remarkably exhibited.

  According to a fifth aspect of the present invention, the predetermined range is a range of 49 N / m to 294 N / m (5 kg / m to 30 kg / m).

  If it is less than 5 kg / m, it is difficult to obtain the effect of smoothing the surface of the magnetic layer. Moreover, when larger than 30 kg / m, the location of the cutting | disconnection formed in a magnetic layer will increase.

  According to the fifth aspect of the present invention, it is possible to suppress the formation of a cut in the magnetic layer while obtaining the surface smoothing effect of the magnetic layer.

  The predetermined range is preferably a range of 78.4 N / m to 245 N / m (8 kg / m to 25 kg / m). Thereby, the effect by the invention of Claim 3 is acquired more notably.

The invention according to claim 6 heats the calender roll on the magnetic layer side of the web.
Thereby, the surface of the magnetic layer can be flattened while performing heat treatment of the magnetic layer in the step of nip with the calender roll.

  According to the present invention, a good magnetic recording medium having excellent surface smoothness can be efficiently produced.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIGS. 1 and 2, in this embodiment, the web W in which the magnetic layer 12 is formed on one side of the long support 10 is calendered. In this calendering process, by niping with a pair of calender rolls 16 and 18, the web W whose magnetic layer surface is not smoothed as shown in FIG. As shown in FIG. 2B, the surface of the magnetic layer is made smooth. A nonmagnetic layer 14 is formed between the magnetic layer 12 and the support 10, and a backcoat surface WB is formed on the surface of the support 10 where the magnetic layer 12 is not formed.

  In this embodiment, the calendar rolls 16 and 18 are both made of metal, the calendar roll 16 wrapped on the web W is heated, and the calendar roll 18 provided in a pair with the calendar roll 16 is cooled (water cooled). Has been. With this configuration, the magnetic layer 12 is heat-treated by the calendar roll 16. In this heat treatment, the temperature of the magnetic layer 12 is preferably in the range of 60 to 120 ° C.

  In this embodiment, the web is conveyed and nipped with the magnetic layer 12 facing upward. Further, the web tension (web tension) along the conveying direction at the nip outlet E is set in a range of 49 N / m to 294 N / m (5 kg / m to 30 kg / m). The web tension is calculated based on, for example, a force applied to a roll (for example, the roll 19 or the roll 20 shown in FIG. 1) passing the web W drawn from the nip outlet.

  Then, following the nip, the web W is wrapped on the magnetic layer side calendar roll 16 at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip outlet E. Within this range, for example, even if θ is 10 ° (see the web W indicated by the solid line in FIG. 1), about 100 ° or 179 ° (both refer to the web W indicated by the two-dot chain line in FIG. 1). It may be.

  As described above, the web tension (web tension) along the conveyance direction at the nip outlet E is in the range of 49 N / m or more and 294 N / m or less (5 kg / m or more and 30 kg / m or less). The web tension used to control the dimensional stability in the in-plane direction is used to improve the surface smoothing of the magnetic layer. Then, the web W is wrapped on the magnetic roll calender roll 16 at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip outlet E. Thereby, the surface roughness of the magnetic layer 12 of the web W away from the calender roll 16 after finishing the nip step can be reduced, and a good magnetic tape excellent in surface smoothness can be efficiently manufactured. .

  In this embodiment, the magnetic layer 12 is conveyed and nipped with the magnetic layer 12 on the upper side. However, the same effect can be obtained even when the magnetic layer 12 is conveyed and nipped with the magnetic layer 12 on the lower side as shown in FIG. Further, the same effect can be obtained even when the web W is conveyed in a direction intersecting the horizontal direction.

<Test Example 1 (Test Example of First Embodiment)>
In order to confirm the effect of the present invention, the present inventor made three examples of the magnetic tape manufacturing method described in the first embodiment (hereinafter referred to as Examples 1 to 3) and a magnetic tape manufacturing method for comparison. Four examples (hereinafter referred to as Comparative Examples 1 to 4) were performed.

  In Example 1 and Comparative Examples 1 and 2, the web tension at the nip outlet E was kept constant at 12 kg / m, and the wrap angle θ was changed as a parameter. In Examples 2 and 3, and Comparative Examples 3 and 4, the wrap angle was kept constant at 10 °, and the web tension at the nip exit E was changed as a parameter. Tables 1 and 2 show the test conditions.

なお、本試験例では、カレンダロール１６、１８のロール径は何れも１００ｍｍφ、支持体１０の厚みは５．０μｍ、磁性層１２の厚みは０．１０μｍ、磁性層１２と支持体１０との間に形成されている非磁性層１４の厚みは１μｍである。

In this test example, the roll diameters of calendar rolls 16 and 18 are both 100 mmφ, the thickness of support 10 is 5.0 μm, the thickness of magnetic layer 12 is 0.10 μm, and between magnetic layer 12 and support 10. The thickness of the nonmagnetic layer 14 formed in 1 is 1 μm.

  The inventor measured the surface roughness Ra of the magnetic layer of the web after the nip step away from the calender rolls 16 and 18 with an AFM (atomic force microscope). In addition, the presence or absence of process cutting (the problem that the web is cut in the calendar process and continuous processing cannot be performed) was also examined. The measurement results and survey results are also shown in Table 1.

  As can be seen from Tables 1 and 2, in Examples 1 to 3, the surface roughness Ra by AFM was significantly smaller than those in Comparative Examples 1 and 3. Further, in Examples 1 to 3 and Comparative Examples 1 and 3, no process cutting occurred in the magnetic layer, but in Comparative Examples 2 and 4, a process cutting occurred in the magnetic layer.

  Other test conditions and test procedures are shown below. In this embodiment, “parts” means “parts by weight” in the following description.

1. Preparation of magnetic layer coating solution Ferromagnetic needle metal powder 100 parts composition: Fe / Co / Al / Y = 65/20/8/7 (atomic ratio)
Surface treatment layer: Al ₂ O ₃ , Y ₂ O ₃ coercive force (Hc): 183 kA / m
Crystallite size: 12.5nm
Average long axis length: 45 nm
Average needle ratio: 6
BET specific surface area (S _BET ): 60 m ² / g
Saturation magnetization (σs): 140 A · m ² / kg (140 emu / g)
Vinyl chloride copolymer 12 parts polyurethane resin 8 parts branched side chain-containing polyester polyol / diphenylmethane diisocyanate,
Hydrophilic polar group: —SO ₃ Na = 70 eq / ton-containing phenylphosphonic acid 3 parts carbon black (average particle size 20 nm) 2 parts cyclohexanone 110 parts methyl ethyl ketone 100 parts toluene 100 parts butyl stearate 2 parts stearic acid 1 part

2. Preparation of non-magnetic layer coating solution Non-magnetic inorganic powder 85 parts α-iron oxide surface treatment layer: Al ₂ O ₃ , SiO ₂ average major axis diameter: 0.15 μm
Tap density: 0.8g / ml
Average needle ratio: 7
BET specific surface area (S _BET ): 52 m ² / g
pH 8
DBP oil absorption: 33ml / 100g
Abrasive material α-Al ₂ O ₃ 15 parts (manufactured by Sumitomo Chemical Co., Ltd., trade name: AKP-30, average particle size = 0.4 μm)
Carbon black 20 parts DBP oil absorption: 120ml / 100g
pH: 8
BET specific surface area (S _BET ): 250 m ² / g
Volatile content: 1.5%
Vinyl chloride copolymer 10 parts polyurethane resin 8 parts branched side chain containing polyester polyol / diphenylmethane diisocyanate,
Hydrophilic polar group: —SO ₃ Na = 70 eq / ton-containing phenylphosphonic acid 3 parts α-Al ₂ O ₃ (average particle size 0.2 μm) 1 part cyclohexanone 140 parts methyl ethyl ketone 170 parts butyl stearate 2 parts stearic acid 1 part

  The components for forming the magnetic layer and nonmagnetic layer coating solutions were kneaded with an open kneader and then dispersed using a sand mill. 6 parts of trifunctional low molecular weight polyisocyanate compound (Coronate 3041 made by Nippon Polyurethane) and 40 parts of methyl ethyl ketone were added to each of the obtained dispersions, and further stirred and mixed for 20 minutes, and then a filter having an average pore size of 1 μm was used. Then, a magnetic layer coating solution and a nonmagnetic layer coating solution were prepared.

3. Preparation (dispersion) of coating solution for backcoat layer
The following composition was placed in a ball mill and dispersed for 24 hours.
Carbon black 180 parts made by Cabot: Regal 250
Average particle size: 34 nm
BET specific surface area: 55 m2 / g
Carbon black 2 5 parts made by Cabot: Black Pearls 130
Average particle size: 75 nm
BET specific surface area: 25 m2 / g
α-Fe2O3 1 part Toda Kogyo Co., Ltd .: TF100, average particle size: 0.1 μm
Nitrocellulose resin 35 parts Polyester polyurethane resin (Toyobo Co., Ltd .: UR-8300) 65 parts MEK 260 parts Toluene 260 parts Cyclohexanone 260 parts

The following composition was mixed and stirred in the dispersed slurry, and then dispersed again for 3 hours in a ball mill.
Stearic acid 1 part Butyl stearate 2 parts MEK 210 parts Toluene 210 parts Cyclohexanone 210 parts

  1 part by weight of an isocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., Coronate-L) is added to 100 parts by weight of the paint after filtration, and the mixture is stirred and mixed, filtered using a filter having an average pore size of 0.5 μm, and a backcoat coating solution Adjusted.

4). Production of Magnetic Tape The obtained magnetic layer coating solution and non-magnetic layer coating solution were mixed with a polyethylene naphthalate (PEN) support (thickness: 5.0 μm, length (MD) direction Young's modulus 6.3 GPa, width ( TD) Young's modulus in the direction 8.3 GPa, center line average surface roughness Ra of the magnetic layer coating surface: 2 nm (cutoff value: 0.25 mm)), and the thickness after drying in the order of the nonmagnetic layer and the magnetic layer. Simultaneous multi-layer coating was performed so that the thickness was 1.0 μm and 0.10 μm, respectively. Next, while the magnetic layer was still wet, orientation treatment was performed using a cobalt magnet having a magnetic flux density of 300 mT (3000 gauss) and a solenoid having a magnetic flux density of 150 mT (1500 gauss). Thereafter, the magnetic layer was formed by drying. Thereafter, the back layer coating solution was applied to the other side of the support (the side opposite to the magnetic layer) so that the thickness after drying was 0.5 μm, and dried to form a back layer. A magnetic recording laminate roll having a magnetic layer on one side of the support and a back layer on the other side was obtained. The above roll is a one-stage calendar roll composed only of a metal roll having a diameter of 100 mm, a temperature of 245 kN / m (250 kg / cm), a temperature of 90 ° C., and a calendar exit wrap angle of 10 so that the magnetic surface is drawn along the metal roll. The surface was smoothed at a tilt of 12 kg / m and a speed of 100 m / min, followed by heat treatment at 70 ° C. for 48 hours and slitting into a 1/2 inch width. Thereafter, the film was wound into a cartridge, and a magnetic tape according to the present invention was produced and evaluated.

  Regarding the magnetic layer surface roughness Ra, the magnetic layer surface roughness Ra was measured with a VN-8000 manufactured by Keyence Corporation at a measurement visual field of 40 μm square.

  About the presence or absence of process cutting, the 5000 m original fabric was processed by 4 rolls, and the presence or absence of cutting and the number of times of cutting were recorded.

[Second Embodiment]
Next, a second embodiment will be described. In the present embodiment, the step of niping the web W having the magnetic layer 12 formed on one side thereof twice in succession by a calendar roll is performed.

  In the present embodiment, as shown in FIG. 4, a pair of calendar rolls 22 and 24 that perform the first nip, and a pair of calendar rolls that perform the second nip on the downstream side of the calendar rolls 22 and 24 in the web conveyance direction. 26 and 28 are provided. The calender rolls 22, 24, 26, and 28 are all metallic, the calender rolls 22 and 26 are heated, and the calender rolls 24 and 28 are cooled (water cooled).

  When the temperature of the calender roll 26 niped in the subsequent stage is made higher than that of the calender roll 22 niped in the previous stage, preheating is performed in the first nip, and main heat treatment is performed in the second nip, the temperature of the web W is rapidly increased. Is preferably avoided.

  Further, a press roll 30 that abuts on the back coat surface WB of the web W is provided between the calender rolls 22 and 24 and the calender rolls 26 and 28. In addition, the setting arrangement position of the pressing roll 30 may be variable in the vertical direction of the paper in FIG.

  In this embodiment, the web W is conveyed and nipped with the magnetic layer 12 on the upper side in FIG. Further, at the nip outlet E in the second nip, the web tension (web tension) along the conveying direction is 49 N / m or more and 294 N / m or less (5 kg / m or more and 30 kg / m or less) as in the first embodiment. Range.

  Then, the web W is wrapped on the magnetic roll side calendar roll 28 at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip outlet E.

  As described above, in this embodiment, the web tension (web tension) along the conveyance direction at the nip outlet E is in the range of 49 N / m or more and 294 N / m or less (5 kg / m or more and 30 kg / m or less). . Then, the web W is wrapped on the magnetic roll calender roll 28 at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip outlet E. As a result, the surface roughness of the magnetic layer 12 is small in the web W separated from the calender roll 28 after finishing the second half nip, that is, the second nip. Therefore, a good magnetic tape with excellent surface smoothness can be produced efficiently.

[Third Embodiment]
Next, a third embodiment will be described. In the present embodiment, similarly to the second embodiment, a step of niping the web W having the magnetic layer 12 formed on one side thereof twice with a calendar roll is performed.

  In the present embodiment, as shown in FIG. 5, the calender roll 32 with which the magnetic layer 12 abuts, the calender roll 34 that performs the first nip between the calender roll 32, and the web W after the first nip is completed. A reversing roll 36 for reversing the conveying direction of the paper and a calender roll 38 for performing a second nip with the calender roll 32 are provided.

  Here, the calendar rolls 32, 34, 38 are arranged in a line in the vertical direction, and the calendar roll 32 is sandwiched between the calendar roll 34 and the calendar roll 38. Then, due to the weight of the calender rolls 32 and 34, the pressure received by the web W is higher in the second nip than in the first nip.

  The calendar rolls 32, 34, 38 are all made of metal, the calendar roll 32 is heated, and the calendar rolls 34, 38 are cooled (water cooled).

  Further, a pressing roll 40 that abuts on the backcoat surface WB of the web W is provided on the downstream side in the transport direction of the nip outlet E in the second nip. Here, the position of the reversing roll 36 is adjusted in advance so that the web W is wrapped by the calender roll 32 on the magnetic layer side at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip exit E. ing.

  In addition, the setting arrangement position of the pressing roll 40 may be variable in the vertical direction of the drawing sheet in FIG. 5 and the horizontal direction of the drawing sheet. Thereby, the wrap angle θ can be adjusted by adjusting the position of the pressing roll 40.

  In the present embodiment, as shown in FIG. 5, the web W is conveyed with the magnetic layer 12 in contact with the calendar roll 32, and the first nip is performed between the calendar roll 32 and the calendar roll 34. Then, the web W is wound around the reversing roll 36, and the second nip is performed by the calender roll 32 and the calender roll 38.

  Here, the web tension (web tension) along the conveying direction at the nip outlet E (that is, the nip outlet at the second nip) between the calender roll 32 and the calender roll 38 is 49 N / s as in the first embodiment. m to 294 N / m or less (5 kg / m to 30 kg / m).

  Furthermore, the web W is wrapped on the calender roll 38 on the magnetic layer side at a wrap angle θ in a range larger than 0 ° and smaller than 180 ° from the nip exit E.

  According to the present embodiment, the surface roughness of the magnetic layer 12 is small in the web W that has finished the second nip subjected to the maximum pressure and is separated from the calendar roll 28. Therefore, a good magnetic tape with excellent surface smoothness can be produced efficiently. Further, even if the number of the heated calender rolls in contact with the magnetic layer 12 is reduced by one as compared with the second embodiment, two nips can be performed.

  Note that, as shown in FIG. 6, arranging the calender rolls in a line in the vertical direction as in this embodiment means that the calender rolls K to be heated and the calender rolls S to be water-cooled are alternately arranged from the upper stage. This is often the case when the web is sequentially niped to the lower stage. When nips are made in multiple stages in this way, normally, the web W receives a higher pressure in the lower nip than in the upper nip due to the weight of the calender roll. Accordingly, the web tension at the nip outlet is within a predetermined range at the nip in the latter half, and the web W is wrapped on the magnetic layer side calendar roll at a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet. By doing so, the surface roughness of the magnetic layer of the web W finally away from the calendar roll can be effectively reduced.

<Test Example 2 (Test Example of Third Embodiment)>
In order to confirm the effect of the present invention, the present inventor made four examples of the magnetic tape manufacturing method described in the third embodiment (hereinafter referred to as Examples 4 to 7) and a magnetic tape manufacturing method for comparison. Five examples (hereinafter referred to as Comparative Examples 5 to 9) were performed.

  In Examples 4 and 5 and Comparative Examples 5 to 7, the web tension at the nip outlet E was kept constant at 12 kg / m, and the wrap angle θ was changed as a parameter. In Examples 6 and 7 and Comparative Examples 8 and 9, the first wrap angle is 0 °, the second wrap angle is 10 °, and the web tension at the nip outlet E is changed as a parameter. It was. Tables 3 and 4 show the test conditions.

なお、本試験例では、試験例１と同様、カレンダロール３２、３４、３８のロール径は何れも１００ｍｍφ、支持体１０の厚みは５μｍ、磁性層１２の厚みは１００ｎｍ、磁性層１２と支持体１０との間に形成されている非磁性層１４の厚みは１μｍである。

In this test example, the roll diameters of the calendar rolls 32, 34, and 38 are all 100 mmφ, the thickness of the support 10 is 5 μm, the thickness of the magnetic layer 12 is 100 nm, and the magnetic layer 12 and the support are the same as in Test Example 1. 10 has a thickness of 1 μm.

  The inventor measured the surface roughness Ra of the magnetic layer of the web after completion of the second nip step away from the calendar roll 32 by AFM. In addition, the presence or absence of process cutting was also examined. The measurement results and survey results are also shown in Tables 3 and 4.

  As can be seen from Tables 3 and 4, in Examples 4 to 7, the surface roughness Ra by AFM was significantly smaller than those of Comparative Examples 5, 6, and 8. In Examples 4 to 7 and Comparative Examples 5, 6, and 8, no process cutting occurred in the magnetic layer, but in Comparative Examples 7 and 9, process cutting occurred in the magnetic layer.

  Other test conditions and test procedures are basically the same as those in Test Example 1 except that the treatment is performed with two-stage calendar rolls.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

In 1st Embodiment, it is a side view explaining nipping a web with a calender roll. 2A and 2B are a side cross-sectional view of the magnetic tape before the start of the nip process and a side cross-sectional view after the end of the nip process, respectively, in the first embodiment. It is a side view explaining the modification of nipping a web with a calendar roll in 1st Embodiment. In 2nd Embodiment, it is a side view explaining nipping a web over two steps with a calendar roll. In 3rd Embodiment, it is a side view explaining nipping a web over two steps with a calendar roll. In 3rd Embodiment, it is a side view explaining nip | ripening a web over multiple steps with a calendar roll.

Explanation of symbols

10 Support 12 Magnetic Layer 16 Calendar Roll 18 Calendar Roll 22 Calendar Roll 24 Calendar Roll 26 Calendar Roll 28 Calendar Roll 32 Calendar Roll 34 Calendar Roll 38 Calendar Roll E Nip Outlet K Calendar Roll S Calendar Roll W Web θ Lap Angle

Claims (6)

A method for producing a magnetic recording medium, comprising performing a step of niping a web having a magnetic layer on one side with a calender roll,
The web tension along the conveyance direction at the nip outlet is within a predetermined range, and the web is wrapped on the calender roll on the magnetic layer side at a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet. And manufacturing method of magnetic recording medium. A method for producing a magnetic recording medium, comprising performing a step of continuously niping a web having a magnetic layer formed on one side thereof twice or more with a calender roll,
At least the web tension along the conveyance direction at the nip outlet in the second nip is within a predetermined range, and the calender roll on the magnetic layer side has a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet. A method of manufacturing a magnetic recording medium, wherein the web is wrapped. A method for producing a magnetic recording medium, comprising performing a step of continuously niping a web having a magnetic layer formed on one side thereof twice or more with a calender roll,
At least the web tension along the conveying direction at the nip outlet in the nip where the web is subjected to the maximum pressure is within a predetermined range, and the magnetic layer has a wrap angle in a range larger than 0 ° and smaller than 180 ° from the nip outlet. A method of manufacturing a magnetic recording medium, wherein the web is wrapped on a calender roll on the side. A method for producing a magnetic recording medium, comprising performing a step of continuously niping a web having a magnetic layer formed on one side thereof twice or more with a calender roll,
At least the nip at which the web is subjected to the maximum pressure, and the web tension along the conveying direction at the nip outlet in the subsequent nips are within a predetermined range, and a range larger than 0 ° and smaller than 180 ° from the nip outlet A method for producing a magnetic recording medium, wherein the web is wrapped on a calender roll on the magnetic layer side at a wrap angle of.   5. The method of manufacturing a magnetic recording medium according to claim 1, wherein the predetermined range is a range of 49 N / m or more and 294 N / m or less.   The method for producing a magnetic recording medium according to claim 1, wherein a calender roll on the magnetic layer side of the web is heated.

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