JP2016127151A - Method of manufacturing cut sintered ferrite sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cut sintered ferrite sheet where the front and rear surfaces do not stick each other, even if a plurality of ferrite green sheets are stacked and fired.SOLUTION: A material of ferrite green sheet is spread on a long carrier sheet having specific surface characteristics on the surface. Specific rough surface of the long carrier sheet is transferred to the rear surface (restricted surface) of the ferrite green sheet thus obtained. The surface of the ferrite green sheet on the opposite side is not restricted but a free surface. A plurality of the ferrite green sheets are stacked and fired. The rubbing surfaces of the sintered ferrite sheet thus obtained do not stick each other, and whereby slidability is improved.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a cut sintered ferrite sheet, and more particularly to a method for producing a cut sintered ferrite sheet by firing a cut ferrite green sheet.

A method for producing a sintered ferrite sheet from a ferrite green sheet is well known. Among them, there is a method described in paragraphs “0082” and “FIG. 12” in Japanese Patent Laid-Open No. 2005-340759 (Patent Document 1). That is, a ferrite raw material kneaded material is spread on a long carrier sheet and formed into a ferrite green sheet, and after separating the ferrite green sheet from the long carrier sheet, it is formed into a predetermined planar shape. There is a method for producing a cut sintered ferrite sheet comprising a cutting step of cutting to obtain a large number of cut ferrite green sheets and a firing step of firing the cut ferrite green sheets.

In the above-mentioned Patent Document 1, although slightly different depending on the physical properties of the ferrite raw material kneaded material, the extended material formed from the raw material kneaded material obtained by extending the long carrier sheet, that is, a ferrite green having a thickness of 30 to 500 μm In the sheet, the surface (front surface) on the back side with respect to the surface (back surface) placed on the long carrier sheet is generally a free surface that has not been subjected to a load from the outside.

Also, in Japanese Patent No. 5360350 (Patent Document 2), the surface characteristics are set to 170-800 nm in terms of center line average roughness and 3 mm in maximum height by a method similar to the method described in Patent Document 1. The area occupancy ratio (hereinafter referred to as “1/2 area occupancy ratio) when the cut surface is virtually cut at a height of ½ of the maximum height of 0 to 10 μm and 100 μm square ferrite green sheets. The ferrite green sheet adjusted to 10 to 80% is disclosed. Here, the “surface characteristics” is a general term for physical parameters expressing the surface roughness of the ferrite green sheet and the sintered ferrite sheet, and it is one or two that affect the effects of the present invention described later. It refers to characteristic values such as centerline average roughness (Ra) and maximum height (Rz), such as more than seed parameters.

Further, the back surface of the ferrite green sheet placed on the long carrier sheet is subjected to an external load that is a reaction due to the weight of the obtained extension as it is to form a constraining surface, and the constraining surface is formed of the carrier sheet. Depending on the surface characteristics, the rough surface is generally slightly larger than the free surface.

JP 2005-340759 A Japanese Patent No. 5360350

A plurality of sheets obtained by stacking a plurality of cut ferrite green sheets having such surface characteristics on top and bottom so that the free surface and the constraining surface rub against each other and firing it. Of the cut sintered ferrite sheets, the cut sintered ferrite sheets that are in contact with each other may stick to each other depending on the firing temperature and surface characteristics. As a result, there is a problem that the quality and performance of the cut sintered ferrite sheet obtained as the target product cannot be fully exhibited depending on the application.

Therefore, the problem of the present invention is that the surface characteristics of the free surface have a center line average roughness of 150 to 300 nm, a maximum height of 2.0 to 5.0 μm, and a half area occupation ratio of 50. Even if the cut ferrite green sheet of ~ 95% is sintered at a temperature of 800 to 1000 ° C, the obtained cut sintered ferrite sheet does not adhere at all, and a cut sintered ferrite sheet having good sliding property is obtained. There is. In the present invention, “sliding is good” means that a force applied in the sliding surface direction is small in order to start sliding one of the stacked sintered ferrite sheets.

In addition, there exists invention of patent 5360350 gazette (patent document 2) as a well-known technique which solves such a subject. However, as described in detail below, this known technique is completely different from those of the present invention in terms of a fundamental technical idea and a problem for preventing sticking of the cut sintered ferrite sheet.

In Patent Document 2, a surface of a carrier sheet is roughened, a ferrite raw material kneaded material is spread thereon to form a ferrite green sheet, and the center line average roughness is set to 370 nm on the back surface of the ferrite green sheet. Discloses a technique for firing a cut ferrite green sheet having a maximum height of 4.0 μm and a ½ area occupation ratio of 75%. According to this known technique, among the obtained plurality of cut sintered ferrite sheets, there is an effect that the cut sintered ferrite sheets in contact with each other do not adhere to each other and are easily separated (paragraphs “0063-0064”. "Column).

Further, the free surface of this ferrite green sheet has a surface characteristic of 104 nm as the center line average roughness, 1.3 μm as the maximum height, and 93% as a ½ area occupancy (paragraph “0064” column). ).

However, in Patent Document 2, when the back surface of the ferrite green sheet has a surface property that is significantly greater than the free surface of the surface, the surface property of the back surface (restraint surface) formed by receiving an external load from the carrier sheet There is no specific description about the range.

Patent Document 2 states that when a cut ferrite green sheet having a center line average roughness of 1120 nm on the constraining surface is used, the cut sintered ferrite sheet obtained by sintering does not stick (paragraph “0076”). Table 1) shows a case where there is no free surface of the cut ferrite green sheet and both the front and back surfaces are constrained surfaces.

Furthermore, the said patent document 2 describes in the claim as "the surface roughness of at least one surface is centerline average roughness ... (omitted)". Examining the invention of Patent Document 2 in light of this description, it is based on the technical idea that both the front surface and the back surface of the ferrite green sheet have the same surface characteristics (see paragraph “0064”) ( In addition, even if the above surface characteristics are adopted for one surface, Patent Document 2 does not disclose a technical idea of how to make other surface characteristics larger than the above surface characteristics.

In order to solve the above-mentioned problems, the present invention extends the kneaded material of the ferrite raw material on a long carrier sheet having a roughened surface, and reacts its own weight on the back surface of the obtained extended material. The constraining surface is formed by substantially transferring the rough surface of the long carrier sheet by applying an external load, and the constraining surface is exposed to the outside without applying any external load to the surface of the extension. Forming a ferrite green sheet having an equivalent thickness of 30 to 500 μm, and a free surface having the following surface characteristics smaller than the surface characteristics of the surface, and cutting the ferrite green sheet into a predetermined planar shape A plurality of the cut ferrite green sheets and a plurality of the cut ferrite green sheets stacked so that the restraining surface and the free surface directly rub against each other. A method for producing a cut sintered ferrite sheet comprising a stacking step of obtaining a stacked green sheet and a firing step of baking the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet. adopt;
(1) Center line average roughness: 150 to 300 nm,
(2) Maximum height: 2.0 to 5.0 μm,
(3) 1/2 area occupancy: 50-95%.

Furthermore, the present invention provides an external load due to the reaction of its own weight on the back surface of the obtained extended product by extending the kneaded product of the ferrite raw material on a long carrier sheet having a roughened surface, The rough surface of the long carrier sheet is substantially transferred and the constraining surface having the following surface characteristics is exposed to the outside without applying any external load to the surface of the extended object. Forming a ferrite green sheet having an equivalent thickness of 30 to 500 μm, having a free surface having surface characteristics smaller than the surface characteristics, and cutting the ferrite green sheet into a predetermined planar shape to obtain a large number of sheets A cutting process for obtaining a cut ferrite green sheet, and a plurality of the cut ferrite green sheets stacked in such a manner that the constraining surface and the free surface directly rub against each other. Adopting a stacking step to obtain a Nshito, a method of making a cutting sintered ferrite sheet comprising a firing step to obtain a fired to cut sintered ferrite sheet in a temperature range of 800 to 1000 ° C. the stacking green sheets;
(1) Centerline average roughness: 850 to 1500 nm,
(2) Maximum height: 7 to 15 μm,
(3) 1/2 area occupancy: 40-65%.

Furthermore, the present invention provides an external load due to the reaction of its own weight on the back surface of the obtained extended product by extending the kneaded product of the ferrite raw material on a long carrier sheet having a roughened surface, The constraining surface having the surface characteristics described in the following (1), which is substantially transferred from the rough surface of the long carrier sheet, and exposed to the outside without applying any external load to the surface of the extended article A forming step of forming a ferrite green sheet having an equivalent thickness of 30 to 500 μm, including a free surface having surface characteristics described in the following (2), and forming the ferrite green sheet into a predetermined planar shape. Cutting process to obtain a large number of cut ferrite green sheets by cutting and stacking a plurality of the cut ferrite green sheets so that the restraining surface and the free surface directly rub against each other A method for producing a cut sintered ferrite sheet comprising a stacking step for obtaining a green sheet and a firing step for firing the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet Adopt;
(1) Centerline average roughness (Ra1) of constraining surface: 850 to 1500 nm, maximum height (Rz1): 7 to 15 μm, 100 μm square cut ferrite green sheet is ½ the maximum height in the thickness direction Now, the area occupation ratio occupied by the cut surface when virtually cut is 40 to 65%.
(2) Centerline average roughness (Ra2) of free surface: 150 to 300 nm, maximum height (Rz2): 2.0 to 5.0 μm, 100 μm square cut ferrite green sheet having a maximum height of 1 in the thickness direction The area occupation ratio of the cut surface when virtually cut at a height of / 2 occupies the unit area: 50 to 95%.

The present invention more preferably, by extending the kneaded product of the ferrite raw material on a long carrier sheet having a roughened surface, an external load due to the reaction of its own weight is applied to the back surface of the obtained extended product. The constraining surface having the surface characteristics described in the following (1), which is substantially transferred from the rough surface of the long carrier sheet, and the external surface without any external load applied to the surface of the extended object. And a free surface having the surface characteristics described in (2) below, the difference in surface characteristics is the surface characteristics described in (3) below, and the equivalent thickness is 30 to 500 μm. A forming step of forming the ferrite green sheet, a cutting step of cutting the ferrite green sheet into a predetermined planar shape to obtain a plurality of cut ferrite green sheets, and the cut ferrite green sheet A stacking step of stacking a plurality of sheets so that the constraining surface and the free surface directly rub against each other to obtain a stacked green sheet, and firing the stacked green sheets in a temperature range of 800 to 1000 ° C. Adopting a method of producing a cut sintered ferrite sheet comprising a sintering step to obtain a sintered ferrite sheet;
(1) Centerline average roughness (Ra1) of constraining surface: 850 to 1500 nm, maximum height (Rz1): 7 to 15 μm, 100 μm square cut ferrite green sheet is ½ the maximum height in the thickness direction Now, the area occupation ratio occupied by the cut surface when virtually cut is 40 to 65%.
(2) Centerline average roughness (Ra2) of free surface: 150 to 300 nm, maximum height (Rz2): 2.0 to 5.0 μm, 100 μm square cut ferrite green sheet having a maximum height of 1 in the thickness direction The area occupation ratio of the cut surface when virtually cut at a height of / 2 occupies the unit area: 50 to 95%.
(3) The centerline average roughness difference (Ra1-Ra2) between the constraining surface and the free surface is 550-1350 nm, and the maximum height difference (Rz1-Rz2) is 3.5-13 μm.

Furthermore, the present invention provides a cutting method in which the long carrier sheet is made of polyethylene terephthalate having a centerline average roughness (Ra3) larger than the centerline average roughness (Ra1) of the constraining surface in addition to the manufacturing method described above. The manufacturing method of the sintered ferrite sheet is adopted.

Furthermore, the present invention provides a long sintered carrier sheet comprising a cut sintered ferrite sheet in which inorganic fine particles or thermosetting resin fine particles are attached to or mixed in the surface or surface layer of the long carrier sheet. Adopt manufacturing method.

By adopting the above means, the present invention exhibits the following actions. That is, when the upper and lower cut ferrite green sheets adjacent to each other in the stacked green sheet are conceptually shown as a pair of gears, as shown in FIG. 5, the stacked green sheet 50 is cut at the lower level. The ferrite green sheet can be grasped as one lower gear 51a, and the upper cut ferrite green sheet can be grasped as the upper gear 52b meshing with the lower gear 51a. Then, it can be assumed that the teeth 53a and 54b and the tooth grooves 55a and 56b of the gears 51a and 52b are rough surfaces of the cut ferrite sheet.

If the gears 51a, 52b have the same mechanical characteristics such as the shape and size of the gears such as the tooth height, pitch, tip diameter, etc., both the gears 51a, 52b mesh with each other. The teeth of 52b penetrate deeply into each other.

However, as shown in FIG. 6, if the mechanical characteristics of the teeth of the two gears 51a and 52b are different, the teeth of the two gears 51a and 52b naturally do not mesh with each other and do not enter deeply.

In this way, when the surface properties of the cut ferrite green sheet are in the same range, the peak portion of one cut ferrite green sheet and the other cut ferrite in the region where a pair of adjacent cut ferrite green sheets rub against each other. The frequency with which the valleys of the green sheet mesh with each other increases, and as a result, the frequency of the area corresponding to the peak and the area corresponding to the valley of the actual cut ferrite green sheet is low, but the stacked green sheets When subjected to firing at a high temperature, the frequency with which the two stick together increases.

On the contrary, the more the surface characteristics of the cut ferrite green sheet are different, the lower the frequency with which the peak portion of the cut ferrite green sheet and the valley portion of the cut ferrite green sheet are meshed in the rubbing region. When the stacked green sheets are fired at a high temperature, the frequency with which they are fixed is reduced, so that the sliding property is improved.

Therefore, in the present invention, the adhesion between the cut sintered ferrite sheets obtained in the process of firing the cut ferrite green sheets by significantly different the surface characteristics in the rubbing region c of a pair of adjacent cut ferrite green sheets. In order to prevent the occurrence of this problem, pay attention to the meshing between the free surface of one cut ferrite green sheet and the restrained surface of the other cut ferrite green sheet. Identify the surface properties of the free surface of the green sheet.

In addition, according to the above technical idea, the surface characteristics of the constraining surface may be specified. However, as described in Patent Document 1, in the field of the present invention, a ferrite raw material kneaded material on the carrier sheet Since the surface of the obtained ferrite green sheet inevitably becomes a free surface having a specific surface, this is used as it is in the present invention.

In the present invention, as shown in FIG. 1, the ferrite green sheet 1 having an equivalent thickness of H = 30 to 500 μm is used, and the surface characteristic is 150 to 300 nm as the center line average roughness Ra2 of the free surface 11. A cut ferrite green sheet having surface characteristics of 2.0 to 5.0 μm for the maximum height Rz2 and 50 to 95% for a ½ area occupation ratio is used.

Here, the equivalent thickness H means two flat bodies having a slightly larger area than the cut ferrite green sheet (having a surface roughness smaller than the surface roughness of the green sheet), for example, a glass plate When sandwiched between, it means the interval between them. Accordingly, this corresponds to the distance between the parallel surfaces a2 and b2 passing through the apex of the peak portion 13 protruding outward in the free surface 11 of the cut ferrite green sheet and the constraining surface 12 corresponding to the back surface thereof. Further, the maximum height Rz is, as defined in JIS standard (JIS B 0601-2001), a plane a2 that passes through the top of the peak 13 and a valley that is recessed inwardly on the free surface 11. 14 means a difference in height from the plane a1 passing through 14.

Further, the area occupancy means the ratio of the cut surface of the ridge 13 that appears when the ridge 13 is virtually horizontally cut at the middle position of the height difference to a unit area of 100 μm square. The unit area may be 90 μm square or 90 μm × 100 μm instead of 100 μm square depending on the environment of the measuring device or software, but the relative roughness may be any area. The same.

When a stacked green sheet is produced by stacking a plurality of cut ferrite green sheets, the surface characteristics of the constraining surface 12 that rubs against the free surface of the other cut ferrite green sheets in the arbitrary cut ferrite green sheets are as described above. It is much larger than the surface characteristic of the free surface (in other words, the surface characteristic of the free surface is much smaller than that of the constraining surface). The size of the surface property means a value relatively indicating the size of the surface roughness of the cut ferrite green sheet. For example, in the case of the centerline average roughness, the larger the surface roughness, the larger the surface roughness. . Regarding the area occupancy, when the center line average roughness and the maximum height are the same, the lower the area occupancy, the larger the surface characteristics.

In the present invention, preferably, the constraining surface 12 has a center line average roughness Ra1 of 850 to 1500 nm (0.850 to 1.500 μm), a maximum height Rz1 of 7 to 15 μm, and a 1/2 area occupation ratio. Then, a cut ferrite green sheet 1 having a surface characteristic of 40 to 65% is used. More preferably, the difference in surface characteristics between the free surface and the constraining surface is 550 to 1350 nm in terms of centerline average roughness (Ra1-Ra2), and 3.5 to 13 μm in terms of maximum height (Rz1-Rz2). Ferrite green sheet 1 is used.

If Ra1 of the constraining surface is less than 850 nm, it becomes close to Ra2 of the free surface and sticking cannot be completely prevented. On the other hand, if it exceeds 1500 nm, sticking is suppressed, but so-called over spec. turn into. Further, if Rz1 of the constraining surface is less than 7 μm, it becomes close to Rz2 of the free surface and sticking cannot be completely prevented. On the other hand, if it exceeds 15 μm, sticking is suppressed but the so-called overshooting occurs. It becomes spec. Further, in the present invention, although it is slightly different depending on the centerline average roughness and the maximum height, assuming that the centerline average roughness and the maximum height are the same, the occupancy ratio of 1/2 area of the constrained surface is The roughness of the surface is relatively increased to be lower than that of the known document 2.

By adopting the above-mentioned means, the present invention is the stacked green sheet, as shown in FIG. 2, on one first cut ferrite green sheet 2 and another second cut ferrite green sheet. 3, the space in the rubbing region c formed by the free surface 11 of the first cut ferrite green sheet 2 and the constraining surface 12 of the second cut ferrite green sheet 3 spreads up and down and is relatively large.

On the other hand, as in the known technique shown in FIG. 3, the first and second cut ferrite green sheets have relatively small surface characteristics of the constraining surface 12, for example, surface characteristics equivalent to the surface characteristics of the free surface. When 2 and 3 are stacked, the space in the rubbing region c is relatively small.

Furthermore, in the rubbing region c according to the present invention, the frequency of the peak portion of the first cut ferrite green sheet 2 entering the valley portion of the second cut ferrite green sheet 3 is compared with that of the known technique. Is smaller than the known technology.

Therefore, when such a stacked green sheet is fired, as the surface characteristics increase, the stacked green sheet according to the present invention suppresses the occurrence of sticking than the cut sintered ferrite sheet obtained by a known technique. And has an excellent effect of improving sliding life.

It is a conceptual diagram which shows the partial cross section of the cutting ferrite green sheet which concerns on this invention. It is a conceptual diagram which shows the partial cross section of the stacked green sheet which concerns on this invention. It is a conceptual diagram which shows the partial cross section of the stacked green sheet which concerns on a prior art. It is sectional drawing which shows the shaping | molding process based on this invention. It is an expanded sectional view of the A section in Drawing 4 (a). It is a conceptual diagram which simulates the unevenness | corrugation of the stacked green sheet which concerns on a prior art by gears. It is a conceptual diagram which simulates the unevenness | corrugation of the stacked green sheet which concerns on this invention to a gearwheel.

Next, modes for carrying out the present invention will be described with additional drawings.

(Raw material of kneaded material)
First, a ferrite powder, a binder that adhesively bonds the powder, a plasticizer that adjusts the fluidity of the binder, and a solvent (solvent) that makes them easy to mix are prepared. As the ferrite powder, a well-known Ni—Zn—Cu ferrite is adopted, PVB (polyvinyl butyral) is used as a binder in an amount of 5 to 10 parts by weight with respect to 100 parts by weight of the ferrite powder, and butyl butyl phthalate is similarly used as a plasticizer. 1 to 5 parts by weight, and 40 to 80 parts by weight of the solvent is used. The solvent is selected from organic solvents such as glycol ether, methyl ethyl ketone, toluene, methanol, ethanol, and n-butanol.

(Kneading process)
Next, the raw materials are kneaded. The kneading means is not particularly limited, but a ball mill is preferably used. A solvent and ferrite powder are first filled in a ball mill and mixed, and then a binder and a plasticizer are added to the resulting mixture and further mixed. The obtained uniform ferrite raw material kneaded material is sufficiently degassed under reduced pressure in a vacuum vessel to prevent the occurrence of cracks in the extended product obtained in the subsequent molding process.

(Molding process)
Next, a ferrite raw material kneaded product is formed to obtain a ferrite green sheet. As a forming method, using a doctor blade method shown in FIG. 4A, a ferrite raw material kneaded material 23 is discharged and spread on a long carrier sheet 22 from between two blades 21 having a predetermined interval. Thus, the extended article 24 having a predetermined thickness is obtained.

As the elongate carrier sheet, a heat-treated synthetic resin film such as polyethylene terephthalate (PET) or polyimide is used, and preferably PET is used.

The PET film has a specific surface characteristic in which inorganic fine particles or thermosetting resin fine particles are adhered or mixed on the surface or surface layer thereof, that is, larger than the centerline average roughness (Ra1) of the constraining surface. A PET film having a center line average roughness (Ra3) is used. Examples of the PET film having the surface characteristics include those described in JP-A-2007-62179 and the fine particles (Si, carbide, or thermosetting) on the PET green sheet discharged by the doctor blade method. A finely divided resin fine particle) is applied by spraying, and a surface-treated product having a specific surface roughness is used. At this time, the center line average roughness is set to a value larger than the center line average roughness of the constraining surface to be obtained, and specifically, a product whose surface is roughened to a surface roughness of 900 to 1600 nm is desirable.

In the molding step, by using the rough carrier sheet 22 that has been roughened, the unevenness of the long carrier sheet is substantially transferred to the back surface 24a of the extension 24 as shown in FIG. Entropy is reduced. As a result, the constraining surface 12 is formed.

At this time, the surface 24b of the extended article 24 that is not in contact with the long carrier sheet 22 is not subjected to any special external force, so that its entropy is larger than the constraining surface and becomes the free surface 11.

The extension 24 obtained by the extension by the above process is gradually dried and cured to become the ferrite green sheet 1. As for the surface roughness of the obtained ferrite green sheet 1, the centerline average roughness is 850 to 1500 nm and the maximum height is 7.0 to 15 μm on the constrained surface, preferably the centerline average roughness. Is 900 to 1300 nm, and the maximum height is 9 to 12 μm. Moreover, although a 1/2 area occupation rate will be 40 to 80%, Preferably it is 70 to 80%.

(Cutting process)
Next, the ferrite green sheet is cut into a size of 50 mm square, 100 mm square, 200 mm square, etc. to obtain a cut ferrite green sheet.

(Stacking process)
Next, about 2 to 100 sheets of the cut ferrite green sheet are stacked on an alumina setter so that the constraining surface and the free surface rub against each other directly to obtain a stacked green sheet.

(Baking process)
Next, the stacked green sheets are fired to obtain a sintered stack. As for the firing conditions, it is preferable to provide a step of removing binder components and growing ferrite particles using an electric furnace. The binder removal is performed at 150 ° C. to 550 ° C. for 4 to 80 hours, and the ferrite particles are grown at 850 ° C. to 960 ° C. for 1 to 5 hours.

In order to prevent heat deformation and cracking of the cut ferrite green sheet, it is better to remove the binder after maintaining the temperature from room temperature to about 10 to 20 ° C./hour and then maintaining a constant temperature. After that, it is preferable that the temperature is increased at 30 to 60 ° C./hour, and thereafter, the temperature is kept constant and sufficiently sintered to grow ferrite particles, and then gradually cooled. However, the holding temperature, the heating rate, and the firing time are not limited to these ranges, and optimum conditions can be selected depending on the number of ferrite green sheets to be processed.

When the cut ferrite green sheet is fired, a cut sintered ferrite sheet having a centerline average roughness of the constraining surface of 850 nm or more and a maximum height of 5 μm or more is obtained. At this time, if the center line average roughness of the cut ferrite green sheet exceeds 1500 nm or the maximum height exceeds 15 μm, the smoothness is lost, and cracking tends to occur.

(Inspection process)
The sintered stack is obtained in the firing step, but the product must be inspected for each cut sintered ferrite sheet. Therefore, it is necessary to separate the cut sintered ferrite sheets from the sintered stack while maintaining the quality for each sheet. For this purpose, the bimetal is deformed by applying an artificial, mechanical, thermodynamic, electromagnetic or hydrodynamic load to the obtained sintered stack in the elastic region of the sintered ferrite sheet. Or in a micro two-dimensional direction. Then, in the present invention, since the adjacent cut sintered ferrite sheets in the sintered stack do not adhere to each other and have good slidability, the cut sintered ferrite sheet can be easily formed only by applying a very small load. Can be separated into individual sheets.

[Experimental result]
Specific experimental results of the present invention will be given.

[Example]
PVB was mixed with a ball mill using 100 parts by weight of Ni—Zn—Cu ferrite powder adjusted to a cumulative 50% volume particle diameter of 1.0 μm and a binder to obtain a ferrite raw material kneaded product. The obtained ferrite raw material kneaded material was spread on a roughened PET film using a doctor blade method. The PET film is obtained by spraying a kneaded mixture of Si particles and UV curable resin so that the surface characteristics are centerline average roughness Ra3 = 1400 nm and maximum height Rz3 = 12 μm. used. The ferrite raw material kneaded material spread on the PET film is dried and then cut into a predetermined shape. The surface characteristics of the constraining surface are centerline average roughness Ra1 = 1287 nm, maximum height Rz1 = 10.4 μm, 1/2 A cut ferrite green sheet having an area occupancy ratio of 60%, a free-surface surface characteristic of centerline average roughness Ra2 = 266 nm, maximum height Rz2 = 4.0 μm, and ½ area occupancy ratio of 82%. Obtained.

10 sheets of this cut ferrite green sheet are stacked so that the constraining surface and the free surface rub against each other to form a stacked green sheet. This stacked green sheet is placed on an alumina setter and the binder is removed at a temperature of 400 ° C. for 4 hours. And firing for 3 hours at a firing temperature of 900 ° C. to obtain a sintered stack. When the sintered stack was artificially loaded with an elastic region load and inspected, all 10 sheets could be easily separated. The surface properties of the constrained surface of the cut sintered ferrite sheet were 57% in terms of centerline average roughness Ra = 1150 nm, maximum height Rz = 9.4 μm, and ½ area occupancy.

[Comparative Example 1]
The same ferrite raw material kneaded material as in the example was spread on a PET film whose surface characteristics were adjusted to Ra3 = 530 nm and Rz3 = 5.6 μm by a sandblasting process to a constant thickness using a doctor blade method. After drying, it is cut into a predetermined shape, and the surface characteristics of the constraining surface are Ra1 = 370 nm, Rz1 = 4.0 μm, ½ area occupancy is 73%, the surface characteristics of the free surface are Ra2 = 104 nm, Rz2 A cut ferrite green sheet having 1.3 μm and a ½ area occupation ratio of 93% was obtained.

Ten sheets of this cut ferrite green sheet are stacked so that the constraining surface and the free surface rub against each other to form a stacked green sheet. This stacked green sheet is placed on an alumina setter and fired under the same firing conditions as in the examples. A stacked body was obtained. When this sintered stack was inspected by artificially applying a load in the elastic region, the constraining surface and the free surface were fixed during firing and could not be separated, resulting in cracks. The surface properties of the constrained surface of this cut sintered ferrite sheet were 12% in terms of Ra = 292 nm, Rz = 3.5 μm, and ½ area occupancy when the fragments were analyzed.

[Comparative Example 2]
10 sheets of cut ferrite green sheets (surface characteristics are the same as in Example 1) manufactured by the same method as in Example are stacked to form a stacked green sheet so that the constraining surfaces and free surfaces rub against each other. The green sheet was fired under the same conditions as in Example 1 to obtain a sintered stack. When this sintered stack was inspected artificially by applying a load in the elastic region, the free surfaces were fixed to each other during firing and could not be separated. The surface characteristics of the constrained surface of this cut sintered ferrite sheet were 57% in terms of centerline average roughness Ra = 1150 nm, maximum height Rz = 9.4 μm, and 1/2 area occupation ratio, as in the example. .

From this result, when the surface characteristics of the rubbed surface in the ferrite green sheet are close, the ferrite green sheet is fixed on the rubbed surface when stacked and fired. By making it a free surface, even if a plurality of sheets are stacked and baked, the rubbing surfaces are not fixed, and an excellent effect is exhibited that the sliding property is good.

According to the present invention, it is easy to provide appropriate surface characteristics on the constraining surface of the cut sintered ferrite sheet, and the free surface and the constraining surface rub against each other even when fired in a stacked state without using a release powder. A cut and sintered ferrite sheet that does not stick and has good sliding properties is industrially obtained.

1: Ferrite green sheet 2: First cut ferrite green sheet 3: Second cut ferrite green sheet 11: Free surface 12: Restraint surface 13: Mountain portion 14: Valley portion 21: Blade 22: Long carrier sheet 23: Ferrite raw material Kneaded material 24: Extension 24a: Back surface 24b: Front surface 50: Stacked green sheet 51a: Lower gear 51b: Upper gear 53a, 54b: Teeth 55a, 56b: Tooth gap H: Equivalent thickness Ra1, Ra2: Center line average Roughness Rz1, Rz2: Maximum heights a1, a2, b1, b2: Plane c: Rubbing region

Therefore, the subject of the present invention is that the surface characteristics of the free surface have a center line average roughness of 150 to 300 nm, a maximum height of 2.0 to 5.0 μm, and a half area occupation ratio of 50. Even if the cut ferrite green sheet of ~ 95% is sintered at a temperature of 800 to 1000 ° C, the obtained cut sintered ferrite sheet does not adhere at all, and a cut sintered ferrite sheet having good sliding property is obtained. There is. In the present invention, slidability refers to mutual sliding when an external load is applied to at least one of the two cut sintered ferrite sheets stacked so that the constraining surface and the free surface directly rub against each other. For example, a sintered ferrite sheet having good sliding properties starts to slide under a small external load.

(Inspection process)
The sintered stack is obtained in the firing step, but the product must be inspected for each cut sintered ferrite sheet. Therefore, it is necessary to separate the cut sintered ferrite sheets from the sintered stack while maintaining the quality for each sheet. For this purpose, the bimetal is deformed by applying an external load artificially, mechanically, thermodynamically, electromagnetically or hydrodynamically to the obtained sintered stack in the elastic region of the sintered ferrite sheet. Or in a micro two-dimensional direction. Then, first, the cut sintered ferrite sheet is subjected to an external load, but the load is a load in the elastic region, so that no breakage occurs. Next, since the cut sintered ferrite sheet obtained in the present invention has good activity, it slides under a small external load. Therefore, it is possible to separate the cut sintered ferrite sheets one by one from Shoyuiseki critical condition. It should be noted that if sticking occurs between the constraining surface and the free surface, naturally no sliding occurs between the two adjacent cut sintered ferrite sheets. In this way, it is inspected whether or not sticking has occurred in this inspection step.

Claims (6)

By extending a kneaded product of ferrite raw material on a long carrier sheet having a roughened surface, an external load is applied to the back surface of the obtained extended product due to the reaction of its own weight. A constraining surface obtained by substantially transferring a rough surface and the following surface characteristics smaller than the surface characteristics of the constraining surface by exposing it to the outside without applying any external load to the surface of the extended object. A forming step of forming a ferrite green sheet having a free surface and an equivalent thickness of 30 to 500 μm;
Cutting the ferrite green sheet into a predetermined planar shape to obtain a large number of cut ferrite green sheets;
A plurality of the cut ferrite green sheets, a stacking step of stacking so that the constraining surface and the free surface directly rub to obtain a stacked green sheet;
A method for producing a cut sintered ferrite sheet comprising a firing step of firing the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet;
(1) Center line average roughness: 150 to 300 nm,
(2) Maximum height: 2.0 to 5.0 μm,
(3) Area occupancy occupied by the cut surface when the 100 μm square cut ferrite green sheet is virtually cut at a height of ½ of the maximum height in the thickness direction: 50 to 95%. By extending a kneaded product of ferrite raw material on a long carrier sheet having a roughened surface, an external load is applied to the back surface of the obtained extended product due to the reaction of its own weight. A forming step of forming a ferrite green sheet having a corresponding thickness of 30 to 500 μm, which includes a constraining surface having the following surface characteristics by substantially transferring a rough surface;
Cutting the ferrite green sheet into a predetermined planar shape to obtain a large number of cut ferrite green sheets;
A plurality of the cut ferrite green sheets, a stacking step of stacking so that the constraining surface and the free surface directly rub to obtain a stacked green sheet;
A method for producing a cut sintered ferrite sheet comprising a firing step of firing the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet;
(1) Centerline average roughness: 850 to 1500 nm,
(2) Maximum height: 7 to 15 μm,
(3) Area occupancy occupied by the cut surface when the 100 μm square cut ferrite green sheet is virtually cut at a height of ½ of the maximum height in the thickness direction: 40 to 65%. By extending a kneaded product of ferrite raw material on a long carrier sheet having a roughened surface, an external load is applied to the back surface of the obtained extended product due to the reaction of its own weight. The constraining surface having the surface characteristics described in the following (1), which is substantially transferred from the rough surface, and the surface of the extended article is exposed to the outside without applying any external load. 2) a forming step for forming a ferrite green sheet having an equivalent thickness of 30 to 500 μm, comprising a free surface having the surface characteristics described in the section;
Cutting the ferrite green sheet into a predetermined planar shape to obtain a large number of cut ferrite green sheets;
A plurality of the cut ferrite green sheets, and a stacking step of stacking the constraining surface and the free surface so as to directly rub to obtain a stacked green sheet;
A method for producing a cut sintered ferrite sheet comprising a firing step of firing the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet;
(1) Centerline average roughness (Ra1) of constraining surface: 850 to 1500 nm, maximum height (Rz1): 7 to 15 μm, 100 μm square cut ferrite green sheet is ½ the maximum height in the thickness direction Now, the area occupation ratio occupied by the cut surface when virtually cut is 40 to 65%.
(2) Centerline average roughness (Ra2) of free surface: 150 to 300 nm, maximum height (Rz2): 2.0 to 5.0 μm, 100 μm square cut ferrite green sheet having a maximum height of 1 in the thickness direction The area occupation ratio of the cut surface when virtually cut at a height of / 2 occupies the unit area: 50 to 95%. By extending a kneaded product of ferrite raw material on a long carrier sheet having a roughened surface, an external load is applied to the back surface of the obtained extended product due to the reaction of its own weight. The constraining surface having the surface characteristics described in the following (1), which is substantially transferred from the rough surface, and the surface of the extended article is exposed to the outside without applying any external load. And a free surface having the surface characteristics described in the section 2), a difference in surface characteristics is the surface characteristics described in the section (3) below, and a molding process for molding into a ferrite green sheet having an equivalent thickness of 30 to 500 μm When,
Cutting the ferrite green sheet into a predetermined planar shape to obtain a large number of cut ferrite green sheets;
A plurality of the cut ferrite green sheets, and a stacking step of stacking the constraining surface and the free surface so as to directly rub to obtain a stacked green sheet;
A method for producing a cut sintered ferrite sheet comprising a firing step of firing the stacked green sheet in a temperature range of 800 to 1000 ° C. to obtain a cut sintered ferrite sheet;
(1) Centerline average roughness (Ra1) of constraining surface: 850 to 1500 nm, maximum height (Rz1): 7 to 15 μm, 100 μm square cut ferrite green sheet is ½ the maximum height in the thickness direction Now, the area occupation ratio occupied by the cut surface when virtually cut is 40 to 65%.
(2) Centerline average roughness (Ra2) of free surface: 150 to 300 nm, maximum height (Rz2): 2.0 to 5.0 μm, 100 μm square cut ferrite green sheet having a maximum height of 1 in the thickness direction The area occupation ratio of the cut surface when virtually cut at a height of / 2 occupies the unit area: 50 to 95%.
(3) The centerline average roughness difference (Ra1-Ra2) between the constraining surface and the free surface is 550-1350 nm, and the maximum height difference (Rz1-Rz2) is 3.5-13 μm. 5. The cut sintered ferrite sheet according to claim 1, wherein the long carrier sheet is made of polyethylene terephthalate having a centerline average roughness (Ra3) larger than a centerline average roughness (Ra1) of the constraining surface. Production method.   The method for producing a cut sintered ferrite sheet according to any one of claims 1 to 5, wherein the long carrier sheet has an inorganic fine particle or a thermosetting resin fine particle attached or mixed on a surface or a surface layer thereof.

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