JP2008291108A - Friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction material which is excellent in wear resistance, hardly exert strong frictional force on the material to be rubbed and has a high coefficient of friction in a wide temperature range. <P>SOLUTION: The friction material, in which a fibrous base material is bound to fillers by a binder, comprises a CaO compound having ≤4.5 Mohs hardness, at least one salt of a titanic acid compound selected from non-whisker-like alkali metal titanate and non-whisker-like alkali metal-group II element titanate, and Fe<SB>2</SB>O<SB>3</SB>as the fillers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction material used for brakes, clutches, and the like of vehicles such as automobiles, and more specifically, a friction material that has excellent wear resistance, low aggressiveness to a counterpart material, and has a high friction coefficient in a wide temperature range. About.

  Conventionally, a friction material having a fiber base material including potassium titanate fibers (Patent Document 1) and plate-like composite fibers (Patent Document 2) instead of asbestos fibers is known. Like the friction material described in Patent Document 1, the friction material having potassium titanate fibers is excellent in wear resistance and has an advantage of having a high friction coefficient even in a high temperature range of 300 ° C. or higher. . It is known that the reason why the wear resistance is excellent is that potassium titanate fibers form a transfer film during braking. However, such a friction material has a problem that the coefficient of friction is low in a low temperature range, particularly in a normal temperature range of about 20 to 70 ° C.

  As a countermeasure, for example, a method of increasing the amount of filler having a high hardness of about Mohs hardness of about 6.5 to 8 can be considered. However, when the amount of the high-hardness filler is increased, there is a problem that the aggression against the mating material such as the disk rotor and the drum becomes high (the mating material wears). Moreover, when the friction coefficient in a general use temperature range of about 100 to 200 ° C. becomes too high, problems such as so-called brake squealing and high wear resistance cannot be obtained. The reason why high wear resistance cannot be obtained is thought to be because the formation of a transfer film with potassium titanate fibers is hindered by a high-hardness filler.

  Therefore, in the friction material described in Patent Document 2, by containing a composite polycrystalline fiber composed of potassium hexatitanate crystal and titania crystal as a fiber base material, high friction is maintained even in a low temperature range while maintaining high wear resistance. A coefficient is obtained. However, there is a concern that this friction material is highly aggressive against the mating material due to the presence of a hard titania crystal having a Mohs hardness of 7.5.

The friction material is roughly composed of a fiber base material, a filler, and a binder that binds the fiber base material and the filler. In the friction material described in Patent Document 1 and Patent Document 2, As a filler, calcium carbonate (CaCO ₃ ), which is a calcium oxide (CaO) compound, is contained. Generally, the filler is included for adjusting the friction coefficient, adjusting the abnormal noise, preventing rust, and the like, and is sometimes called a friction modifier. For example, the above-mentioned high-hardness filler also corresponds. However, calcium carbonate here is not added for the purpose of directly improving the characteristics of the friction material, and the action of the calcium carbonate is not particularly mentioned. Therefore, the specific content is not described in Patent Document 2. On the other hand, Patent Document 1 contains 17% by weight of calcium carbonate, but if the amount of the CaO compound is too large, the friction material may be adversely affected.

JP 61-191599 A Japanese Patent No. 2990565

  Accordingly, the present invention has an object to provide a friction material that is excellent in wear resistance, has a low aggressiveness to the counterpart material, and has a high coefficient of friction in a wide temperature range by appropriately selecting and blending the filler. And

As a result of intensive studies on the friction material, the present inventors have a limit in improving the properties of the friction material using only the fiber base material, and a material used as a filler (friction modifier) regardless of the fiber base material. It was found that the characteristics of the friction material can be improved by suitably selecting. Furthermore, it discovered that the characteristic of a friction material could be improved more by mix | blending those compounding quantities accurately, and came to complete this invention.
That is, the present invention provides the following means in order to solve the above problems.

The present invention is a friction material in which a fiber base material and a filler are bound with a binder, and the filler includes a CaO compound having a Mohs hardness of 4.5 or less, a non-whisker-like alkali metal titanate, and It contains at least one titanic acid compound salt selected from non-whisker-like alkali metal titanate / group 2 element salts and Fe ₂ O ₃ . In addition, although mentioned later for details, the CaO compound in this invention is the concept which does not contain calcium hydroxide (Ca (OH) ₂ ).

If a titanate compound salt is blended in the friction material as a filler, a transfer film can be formed regardless of the fiber base material, and high wear resistance can be obtained by the transfer film. Moreover, although the friction material of the present invention also contains a CaO compound as a filler, since the Mohs hardness of the CaO compound is 4.5 or less, it is possible to suppress wear of the disk rotor and the like, and to attack the counterpart material ( Low face-to-face attack). Furthermore, since the friction material of the present invention contains Fe ₂ O ₃ as a filler, a high friction coefficient can be maintained even in a low temperature range of about 20 to 70 ° C. In addition, the Mohs hardness of Fe ₂ O ₃ is about 6.0, and it can be used as a general friction modifier (filler) such as ZrO ₂ (Mohs hardness 6.5) or ZrSiO ₄ (Mohs hardness 7.5). Low compared. Therefore, even if Fe ₂ O ₃ is added, there is little fear that the transfer film is broken, and high wear resistance can be maintained. Moreover, since a friction coefficient does not become too high in a general use temperature range of about 100 to 200 ° C. at a relatively low temperature, it is possible to suppress the occurrence of brake squeal. Fe ₂ O ₃ is indefinite and thermally stable compared to Fe ₃ O ₄ which is the same iron oxide. Moreover, according to this friction material, since the fiber etc. which contain the hard titania crystal of Mohs hardness 7.5 which are described in patent document 2 are not required, there is no fear that a face-to-face attack property becomes high.

  At this time, the content of the CaO compound is preferably 0.5 to 11% by weight. By adjusting the content of the CaO compound in such a range, the CaO compound can favorably contribute to wear resistance and the like without adversely affecting the friction material.

  Moreover, it is preferable that content of the said titanic acid compound salt is 5 to 40 weight%. When the content of the titanic acid compound salt is 5% by weight or more, the wear resistance can be largely ensured.

  Moreover, it is preferable that the said titanic acid compound salt is plate shape, flake shape, or powder form. If the titanic acid compound salt is a non-whisker shape such as a plate shape, flake shape or powder shape, the whisker has an unfavorable environmental hygiene length of 5 μm or more, a diameter of 3 μm or less, and an aspect ratio (length / diameter) exceeding 3. Does not contain fiber. Therefore, there is no concern about carcinogenicity to the human body.

The content of the _Fe 2 _{O 3} is preferably from 5 to 23 wt%. By adjusting the content of Fe ₂ O ₃ in such a range, the contact area between Fe ₂ O ₃ and the counterpart material is sufficiently widened, and the transfer film is not damaged and wear resistance is not reduced. Therefore, the friction coefficient in a normal temperature range (low temperature range) of 20 to 70 ° C. is significantly increased.

Moreover, it is preferable that the average particle diameter (median diameter) of the Fe ₂ O ₃ is 0.3 to 4.5 μm. When the average particle size of Fe ₂ O ₃ is 0.3 to 4.5 μm, the amount of Fe ₂ O ₃ added can be increased while maintaining characteristics such as wear resistance in a high state. If the amount of Fe ₂ O ₃ added can be increased, a high friction coefficient can be obtained even in a low temperature range of 20 to 70 ° C. where the lubricity of graphite or the like is high.

  According to the present invention, by appropriately blending the filler, it is possible to obtain a friction material that is excellent in wear resistance, has a low aggressiveness to the counterpart material, and has a high friction coefficient in a wide temperature range.

The friction material according to the present invention mainly includes a fiber base material, a filler (friction modifier), and a binder. The filler (friction modifier) is included for adjusting the coefficient of friction, adjusting abnormal noise, preventing rust, etc., and the friction material according to the present invention is an oxide having a Mohs hardness of 4.5 or less as a filler. It contains a calcium (CaO) compound, a non-whisker-like titanate compound salt, and ferric oxide (Fe ₂ O ₃ ).

  The wear resistance is particularly improved by adding a proper amount of the CaO compound to the friction material. The reason for this is not necessarily clear, but when the friction material and the disk rotor or the like are in sliding contact, a transfer film is mainly produced by the titanate compound salt, but the presence of the CaO compound improves the properties of the transfer film. Conceivable. The blending amount is preferably 0.5 to 11% by weight based on the total amount of the friction material, more preferably 2 to 9% by weight, and further preferably 3 to 7% by weight. When the content of the CaO compound is less than 0.5% by weight, it is difficult to effectively obtain the effect of adding the CaO compound. On the other hand, when the content of the CaO compound is more than 11% by weight, the wear resistance tends to decrease. The reason why the wear resistance tends to be lowered when the content of the CaO compound is too large is considered that the excess CaO compound inhibits the formation of the transfer film.

Such a CaO compound is not particularly limited as long as it has a Mohs hardness of 4.5 or less in consideration of the aggressiveness to a counterpart material such as a disk rotor. For example, calcium silicate (CaO.SiO ₂ , Mohs hardness 4.0), dolomite (CaMg (CO ₃ ) ₂ , Mohs hardness 3.5 to 4.0), calcium sulfate (anhydrite, CaSO 4, Mohs hardness 0.3 to 3.5), calcium carbonate (CaCO 3 , Moss hardness of calcite 3.0, moor hardness of aragonite 3.5-4.0). Of these, calcium silicate is preferred. Examples of calcium silicate include wollastonite (CaSiO ₃ ) and zonorite (6CaO · 6SiO ₂ · H ₂ O) in the form of hydrates thereof. These CaO compounds may be used alone or in combination of two or more. In addition, calcium hydroxide (Ca (OH) ₂ ) that has been conventionally used as a filler is also accurately included in the CaO compound. However, when calcium hydroxide is molded by heating and pressing the friction material, it reacts with a binder (binder resin) made of a synthetic resin that binds the fiber base material and filler, thereby inhibiting the function of the binder. In the present invention, the term CaO compound is used as a concept that does not include calcium hydroxide. However, it does not deny adding calcium hydroxide to the friction material as another filler.

  As the titanic acid compound salt, alkali metal titanate and alkali metal titanate / group 2 element salt can be used, but non-whiskers are used. The non-whisker shape means that no whisker is included, and specifically means a plate shape, flake shape (flaky shape, fish scale shape), powder shape, and the like. Therefore, the titanic acid compound salt of the present invention has a whisker (needle crystal, which has a length of 5 μm or more, a diameter of 3 μm or less, and an aspect ratio (length / diameter) of 3 which is undesirable for environmental hygiene and human influence. (Whisker crystal) is not included. Since the titanic acid compound salt is a main component for producing a transfer film, the amount of the friction material tends to improve as the blending amount increases. Therefore, the blending amount of the titanic acid compound salt is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more based on the total amount of the friction material. When the blending amount of the titanic acid compound salt is less than 5% by weight, it is difficult to effectively obtain the effect of blending the titanium oxide salt. The upper limit of the amount of the titanic acid compound salt may be about 40% by weight.

Typical examples of the alkali metal titanate include potassium titanate, lithium titanate, lithium / potassium titanate, and the like. In addition, an alkali metal salt such as sodium (Na) may be used. Among them, as potassium titanate, potassium _hexatitanate or potassium titanate, for example, plate-like potassium titanate (K ₂ Ti ₆ O ₁₃ ) or flaky potassium potassium titanate (K _{1.88 to 2.13} Ti ₈ O). _16.94-17.07 ) can be preferably used. As lithium lithium potassium titanate, flaky lithium potassium potassium titanate (K _{0.5 to 0.7} Li _0.27 Ti _1.6 O _{3.85 to 3.95} ) or the like can be used.

  Typical examples of alkali metal titanate / group 2 element salts include magnesium titanate and potassium. Here again, other alkali metals such as lithium instead of potassium and metals of other second group elements such as beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba) instead of magnesium It can be salt. These titanic acid compound salts may be used alone or in combination of two or more.

As Fe ₂ O ₃ (ferric oxide), it is desirable to use one having an average particle diameter (median diameter) of 0.3 to 4.5 μm. Fe ₂ O ₃ is for maintaining the coefficient of friction in a low temperature range, but if the average particle size is large, the attacking property against the transfer film and the counterpart material increases. Therefore, the average particle size of Fe ₂ O ₃ is preferably as fine as possible, and specifically, the average particle size is 4.2 μm or less, 3.5 μm or less, and 2.5 μm or less in this order. However, if the average particle size of Fe ₂ O ₃ is less than 0.3, the friction coefficient in the low temperature region cannot be maintained well. Fe ₂ O ₃ may be maghematite (γ type), but is preferably hematite (α type, red iron steel). The blending amount of Fe ₂ O ₃ is preferably 5 to 23% by weight and more preferably 8 to 20% by weight based on the total amount of the friction material. The blending amount of Fe ₂ O ₃ is less than 5% by weight, and it is difficult to effectively obtain the effect of blending Fe ₂ O ₃ . Further, if the amount of Fe ₂ O ₃ exceeds 23 wt%, the hardness wear resistance together with the counterpart material increases tend to be reduced.

In addition to CaO compounds having a Mohs hardness of 4.5 or less, titanic acid compound salts, and Fe ₂ O ₃ , the friction material includes various other inorganic fillers, organic fillers, lubricants, and the like (friction modifier). ). Examples of the inorganic filler include barium sulfate, calcium hydroxide, zirconium oxide, zirconium silicate, mica (mica), kaolin, talc, zonotlite, vermiculite, and sulfide. Examples of organic fillers include rubber, cashew dust, and resin dust. Examples of the lubricant include graphite (graphite), antimony trisulfide, molybdenum disulfide, and zinc disulfide. One or more of these may be appropriately blended depending on the required coefficient of friction and wear resistance. Especially, it is preferable that the high-hardness friction modifier having a Mohs hardness of 6.5 or more is, for example, 10% by weight or less.

The friction material includes a fiber base material in addition to the filler. As the fiber substrate, inorganic fibers, organic fibers, and powders can be used as appropriate. Specifically, examples of inorganic fibers include metal fibers such as copper fibers and iron fibers, carbon fibers, glass fibers, and ceramic fibers. Examples of organic fibers include synthetic resin fibers such as aramid fibers and natural fibers such as pulp. Examples of the powder body include metal powder such as copper powder. These fiber base materials may be used alone or in combination of two or more. The amount of the fiber base is 5 to 40 on the basis of the total amount of the friction material while considering the balance with the amounts of CaO compound, titanic acid compound salt, and Fe ₂ O ₃ that are important as the filler of the present invention. What is necessary is just to adjust suitably in the range of about weight%.

  The friction material also contains a binder in addition to the fiber base material and the filler. This binder binds the fiber base material and the filler, and synthetic resin or rubber is used. For example, thermosetting resins such as phenol resin, imide resin, rubber-modified phenol resin, melamine resin, and epoxy resin, NBR, nitrile rubber, and acrylic rubber can be used. These binders can also be used individually by 1 type, and can also be used in combination of 2 or more type. The blending amount of the binder may be appropriately adjusted while maintaining a balance with the blending amount of the filler and the fiber base material, with 5 to 30% by weight as a guide based on the total amount of the friction material.

  In the manufacturing method of the friction material, first, the friction material raw materials are mixed with a mixer to obtain a raw material mixture. As a mixer, an Eirich mixer, a universal mixer, a Ladige mixer, or the like can be used. Next, the raw material mixture is preformed by a preliminary mold, and the preform is heated and pressed by a molding mold. The molding temperature in the heat and pressure molding is 130 to 200 ° C., the molding pressure is 10 to 100 MPa, and the molding time is 2 to 15 minutes. Next, it is obtained by heat-treating the molded body at 140 to 400 ° C. for 2 to 48 hours to surely cure the friction material.

Hereinafter, Examples 1 to 17 and Comparative Examples 1 to 12 according to the present invention will be described using specific numbers. First, each of these Examples and Comparative Examples was manufactured as follows. Each friction material raw material was mixed by an Eirich mixer for 5 minutes in a dry manner to obtain a raw material mixture. This raw material mixture was heated and pressed under the conditions of a molding temperature of 160 ° C., a molding pressure of 20 MPa, and a molding time of 10 minutes. Finally, the molded product was cured at 230 ° C. for 3 hours. Each Example and Comparative Example is created by changing the type and blending amount of the filler from a specific viewpoint. The specific composition amount is shown in the upper part of Tables 1-5. In each example and comparative example, plate-like potassium titanate (K ₂ Ti ₆ O ₁₃ ) (TXAX-A manufactured by Kubota Corporation) produced by a melt method was used as the titanate compound salt.

Various tests were performed on the friction materials of the examples and comparative examples thus obtained, and the characteristics at that time were compared and examined. The results are shown in the lower part of Tables 1-5. The contents of each test are as follows.
<Friction performance test>
A friction performance test was conducted according to JASO C406, and the average friction coefficient in a general use temperature range (100 ° C.) and a low temperature range (50 ° C.) was measured and determined according to the following criteria.
○: 0.35 or more, ×: less than 0.35 <squeal performance test>
A friction test according to temperature was performed according to JASO C427, and the number of high frequency sounds (sounds of 500 Hz or higher) generated at a predetermined level or higher was measured during the test.
<Abrasion resistance test>
Estimated life: L.A. An actual vehicle running test in an urban area was dropped into a bench test machine (commonly known as LACT test, LACT simulation test), and the estimated life was measured.
○: 21,000 km or more, ×: Less than 21,000 km Friction material wear amount: disc temperature 100 ° C, vehicle speed 50 → 0km / h, deceleration 2.9m / s ² , braking frequency 200 times Thereafter, a sliding test was performed at a disk temperature of 300 ° C. with a vehicle speed of 50 → 0 km / h, a deceleration of 2.9 m / s ² and a braking frequency of 1000 times. The average value obtained by measuring the thickness of the friction material at that time at six points was calculated as the amount of wear, and judged according to the following criteria.
○: Less than 0.5 mm, ×: 0.5 mm or more <face-to-face attack test>
The friction material was pressed against a cast iron disc rotor at 0.05 MPa and slid by a test method according to JIS D 4411, and the wear amount of the mating material after a specified time test was measured.
○: Less than 10 μm, ×: 10 μm or more

First, although the friction material contains a titanate compound salt (plate-like potassium titanate) as a filler, it does not contain a CaO compound, and instead of Fe ₂ O ₃ , zirconium silicate (comparative example) 1, 2) and zirconia (Comparative Example 3) were measured for various characteristics. The results are shown in Table 1.

From the test results of Table 1, in Comparative Example 1 including plate-like potassium titanate and zirconium silicate as fillers, a high friction coefficient is obtained in the general use temperature range (100 ° C.). However, the coefficient of friction in the low temperature range (50 ° C.) remained low. On the other hand, in Comparative Examples 2 and 3 in which the amount of zirconium silicate or zirconia is larger than that of Comparative Example 1, the friction coefficient in the low temperature range (50 ° C.) is high, but conversely, the wear resistance and the facing Aggression and squealing were getting worse. Therefore, it was found that even if zirconium silicate or zirconia was used instead of Fe ₂ O ₃ , good results could not be obtained due to high Mohs hardness.

Next, after blending a titanate compound salt and Fe ₂ O ₃ as fillers in the friction material, what characteristics can be obtained depending on the type of CaO compound and its blending amount were examined. The results are shown in Table 2.

From the test results in Table 2, even though the titanate compound salt and Fe ₂ O ₃ are blended as fillers, the wear resistance is inferior in Comparative Example 4 that does not contain a CaO compound (300 ° C. friction material wear amount) There are many). Moreover, even if the CaO compound is blended in addition to the titanic acid compound salt and Fe ₂ O ₃ , the occurrence of squealing, wear resistance, It can be seen that the face-to-face aggression has greatly deteriorated. On the other hand, Examples 1-4 and Comparative Examples 6- using a CaO compound having a Mohs hardness of 4.5 or less, specifically, calcium sulfate having a Mohs hardness of 2.0 or calcium silicate having a Mohs hardness of 4.0. 7 shows that there is no problem in the face-to-face attack.

  Moreover, if the compounding quantity of a CaO compound is an appropriate quantity of Examples 1-4, it turns out that a favorable result is obtained in various characteristics. The reason for this is not necessarily clear, but it can be seen that, when Comparative Example 4 and Examples 1 to 4 are compared, wear resistance is particularly improved by blending the CaO compound. From this, it is presumed that the presence of the CaO compound contributes to the good production of the transfer film. However, the estimated life tends to be shortened as the CaO compound content increases, and Comparative Examples 6 and 7 with a large amount of CaO compound have a problem in wear resistance. From the above results, it was found that the blending amount of the CaO compound is preferably 0.5 to 11% by weight.

  Next, various amounts of the titanic acid compound salt were changed, and changes in various properties at that time were examined. The results are shown in Table 3.

  When the test result of Table 3 is seen, it turns out that the abrasion resistance of a friction material improves, so that there are many compounding quantities of a titanic acid compound salt. This is because the transfer film is mainly produced from a titanic acid compound salt. Therefore, it can be seen that in Comparative Example 8 in which the amount of the titanic acid compound salt is small, the wear resistance is inferior. From the above results, it was found that the amount of titanic acid compound salt was preferably as large as possible, and preferably at least 5% by weight or more.

Next, the amount of Fe ₂ O ₃ was varied, and changes in various characteristics at that time were examined. The results are shown in Table 4.

Looking at the test results in Table 4, as the amount of Fe ₂ O ₃ is increased, the general use temperature range (100 ° C.) and low temperature region it is understood that the coefficient of friction (50 ° C.) is higher. Therefore, in Comparative Example 9 in which the blending amount of Fe ₂ O ₃ is small, a good friction coefficient in a low temperature range (50 ° C.) is not obtained. However, on the other hand, it can be seen that the wear resistance and the face-to-face attack are deteriorated as the blending amount of Fe ₂ O ₃ increases. Therefore, in Comparative Example 10 in which the amount of Fe ₂ O ₃ is too large, the estimated life is inferior. In contrast, in Examples 11 to 13 having appropriate _Fe 2 _{O 3} amount, good results in various characteristics are obtained. From the above results, it was found that the blending amount of Fe ₂ O ₃ is preferably 5 to 23% by weight.

Next, the average particle diameter of Fe ₂ O ₃ was changed variously, and changes in various characteristics at that time were examined. The results are shown in Table 5.

When the test result of Table 5 is seen, in the comparative example 11 with the smallest average particle diameter, it turns out that the friction coefficient in a low temperature range (50 degreeC) has not improved so much. Comparing Examples 14-17 and Comparative Examples 11-12, it can be seen that the wear resistance and the face-to-face attack tend to be inferior as the average particle size of Fe ₂ O ₃ increases. Therefore, as small as possible preferably in the average particle size is a predetermined size or more ranges of Fe ₂ O _3, in Comparative Example 12 Average particle size of Fe ₂ O ₃ is too large, the abrasion resistance of the (estimated life) Result Is not preferred. On the other hand, in Examples 14-17 which have a moderate average particle diameter, it turns out that it can be used without a problem in various characteristics. From the above results, it was found that the average particle size of Fe ₂ O ₃ is preferably 0.3 to 4.5 μm.

  Although the test results are not clearly shown, instead of plate-like potassium titanate, flake-like potassium titanate (TERRACESS TF-L or TERRACESS TF-S manufactured by Otsuka Chemical Co., Ltd.), flake-like Lithium Potassium Titanate (TERRACESS L manufactured by Otsuka Chemical Co., Ltd.), Flake Magnesium Potassium Titanate (TERRESS PS manufactured by Otsuka Chemical Co., Ltd.), Powdered Potassium Titanate (manufactured by JFE Mineral Co., Ltd.) The same results were obtained using TIBRX-AF).

Claims (6)

A friction material obtained by binding a fiber base material and a filler with a binder,
As the filler, a CaO compound having a Mohs hardness of 4.5 or less, and at least one titanate compound salt selected from a non-whisker-like alkali metal titanate salt and a non-whisker-like alkali metal titanate / group 2 element salt; And a friction material containing Fe ₂ O ₃ . The friction material according to claim 1,
A friction material comprising 0.5 to 11% by weight of the CaO compound. The friction material according to claim 1 or 2,
A friction material comprising 5 to 40% by weight of the titanate compound salt. The friction material according to any one of claims 1 to 3,
The friction material, wherein the titanate compound salt is plate-like, flake-like or powdery. The friction material according to any one of claims 1 to 4,
A friction material containing 5 to 23% by weight of Fe ₂ O ₃ . The friction material according to any one of claims 1 to 5,
Friction material average particle size of the Fe ₂ O _3, characterized in that it is 0.3～4.5Myuemu.