JPS644328B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording medium. For more details,
The present invention relates to a magnetic recording medium made of a thin plate of an alloy having a specific composition, and particularly suitable for various audio tapes, video tapes, magnetic tapes for ultra-large capacity storage devices, and the like. Conventionally, flexible long magnetic tapes have been produced by dispersing γ-iron oxide, alloy magnetic powder, etc. in a solvent together with a binder, coating this on a flexible support such as polyethylene terephthalate, and drying it. Coated magnetic tape is widely used.
However, this coated magnetic tape has a low residual magnetic flux density and a low coercive force, and is not suitable for high-output, high-density magnetic recording, which has become extremely demanding in recent years. On the other hand, continuous thin film magnetic tapes in which a thin magnetic layer is continuously formed on a flexible support by plating, vacuum evaporation, sputtering, ion plating, etc. have recently been actively developed. Since this continuous thin film magnetic tape does not contain a binder component in its magnetic layer, it has a high residual magnetic flux density and a high coercive force, and is a magnetic recording medium suitable for high-output, high-density recording. However, the magnetic layer formed in this way has a problem with its wear resistance, and continuous sliding contact with the magnetic head causes wear and peeling of the thin magnetic layer, resulting in changes in magnetic properties over time. There is. For this reason, various types of protective layers are usually used to cover the upper layer of the magnetic layer. However, by providing a protective layer, the effective gap between the magnetic head and the magnetic layer increases, resulting in an increase in separation loss. As a result, it becomes unsuitable for high-output, high-density recording. In addition, such a continuous thin film magnetic tape requires the formation of a magnetic layer.
Since this is done by plating, vapor deposition, etc., it is not possible to obtain satisfactory mass production in terms of productivity, the manufacturing cost is high, and furthermore, it is difficult to obtain extremely long tapes in one batch. There is a drawback that the quality varies depending on the manufacturing process or each manufacturing batch, making it difficult to control the quality. In view of these circumstances, the present inventors have developed a magnetic recording medium that exhibits a high residual magnetic flux density and a high coercive force, is suitable for high-output, high-density recording, and is particularly suitable for use as a magnetic tape, and that its manufacturing process is It is suitable for mass production, has low manufacturing costs, has little variation in quality during manufacturing, has excellent flexibility as a long magnetic tape, has good contact stability with a sliding magnetic head, and is a floating head type. Various studies were conducted in order to develop a device with stable input/output characteristics that would not fluctuate in floating clearance when used in the field. By the way, as a highly workable permanent magnet material, Cu--
Ni--Fe alloys and the like have been known for a long time. If such a highly workable permanent magnet material is cold-plastically worked into a thin plate, it is thought that it can itself be used as various magnetic recording bodies made of a thin plate-like alloy. For this reason, in practice, for example, Cu-Ni-Fe with a composition consisting of 65 to 75% by weight Cu, 17 to 30% by weight Ni, and the balance 5% or more by weight Fe.
A proposal has been made to create a thin plate with a thickness of 50 μm or more from a series alloy and use it as a fixed magnetic scale for use in distance sensors (Special Publication No. 1983-
Publication No. 4248). However, such Cu,
Cu-Ni-Fe alloy thin plate consisting of Ni and Fe is
Due to the hardness of the thin plate itself, it cannot be used in various magnetic tapes such as cassettes, cartridges, and reel-to-reel devices that require flexibility.
In other words, it may become impossible to run, or even if it does run, the running performance is poor, the running trajectory fluctuates, the contact with the sliding head is unstable, or, in the case of a floating head, the floating clearance is not stable. It is. In addition, it has poor high-frequency characteristics and cannot be used for audio, video, or other purposes. Therefore, the present inventors investigated such Cu-Ni-
After conducting various studies on the conditions for applying Fe-based alloys to flexible long tapes, we found that the plate thickness
It has been found that only when the thickness is 0.5 to 20 μm, it shows critical and satisfactory flexibility only in that thickness range, can be used as a long magnetic tape, and exhibits high-frequency characteristics that are suitable for practical use. . Such 0.5-20 μm plate thickness of Cu, Ni and
The thin alloy plate made of Fe certainly has good runnability and
It has good performance in terms of high frequency characteristics. However, the amount of demagnetization is observed to be quite large due to self-demagnetization under natural storage, demagnetization due to external magnetic field disturbance, or demagnetization due to repeated sliding contact with the read head. It has low durability and requires improvement in the amount of demagnetization. In this case, in the above-mentioned Japanese Patent Publication No. 55-4248, for Cu-Ni-Fe alloys with a diameter of 50 μm or less,
Although demagnetization is generally considered not to be a problem, it actually becomes a major problem in practical use. In addition, the above publication describes Cu, Ni, and Fe, which are richer in Cu than the general composition.
It is disclosed that when a magnetic scale is made by forming a thin plate of 50 μm or more from the Cu-Ni-Fe alloy consisting of Cu-Ni-Fe, the amount of demagnetization as a magnetic scale decreases. However, even as Cu-rich,
When a magnetic tape is made from an alloy with a plate thickness of 20 μm or less, the amount of demagnetization due to various factors does not decrease significantly, which causes problems in recording durability. The present invention was made as a result of such considerations, and is suitable for high output and high density recording, and
Moreover, it is highly mass-producible and has little variation in quality.
In addition, the main object of the present invention is to provide a magnetic recording medium that has extremely low demagnetization due to various factors, has high durability for magnetic recording, and is particularly useful as various magnetic tapes. The present inventors have conducted extensive research for such purposes. As a result, we added various additives to a Cu-Ni-Fe alloy, obtained a thin plate of 20 μm or less from the alloy, used it as a magnetic tape, and evaluated the amount of demagnetization at that time. - It was discovered that the amount of demagnetization becomes significantly smaller only when a predetermined amount of Mn is contained in the Fe-based alloy, and this knowledge led to the creation of the present invention. That is, the present invention provides a magnetic recording medium composed of a thin alloy plate with a thickness of 0.5 to 20 μm, in which the thin alloy plate is made of a workable magnet using spinodal decomposition and has a composition represented by the following formula as a main component. be. Formula [Cu _x Ni _y (Fe _u CO _v ) _z ] _p Mn _q The composition of a thin plate having the composition of the above formula as a main component is shown in more detail by the following formula. Formula [Cu _x Ni _y (F _u Co _v ) _z ] _p Mn _q Mr In both formulas above, the sum of x, y, and z is 100% by weight
, x is 25-80% by weight, y is 10-40% by weight, z is 100-xy% by weight, but 5
It cannot be less than % by weight. Further, the sum of u and v is 100% by weight, and v is 0 to 50% by weight.
Furthermore, M represents one or more additive elements other than Cu, Ni, Fe, Co and Mn, the sum of p and q or the sum of p, q and r is 100% by weight, and q is
0.05 to 10% by weight, and r is 0 to 5% by weight. In this case, the Cu-Ni-Fe alloy containing Mn and having a spinodal decomposition type structure is conventionally known as a permanent magnet material. However, when using such Mn-containing Cu-Ni-Fe alloys,
It is necessary to form a thin plate with a diameter of 20 μm or less, and to use the thin plate as a magnetic recording medium such as a magnetic tape, and furthermore, at that time, the amount of demagnetization is much smaller than that expected from the magnetic properties. It was previously unknown that this would not occur. Furthermore, Patent No. 177984 states that the main ingredients are 15-30% each of nickel and copper, 50-55% iron,
A magnetic recording medium is disclosed in which wires, strips, etc. are made of an alloy containing 10% or less of one or more of manganese, vanadium, molybdenum, dungsten, chromium, and cobalt as subcomponents. However, this material is melted at around 1350℃, cast into a mold, kept in a single phase at high temperature and subjected to solution treatment, and then cold forged into wires, strips, etc. Unlike the thin sheet of the present invention, which is subjected to aging for spinodal decomposition after solution treatment and before processing such as cold rolling, it does not utilize spinodal decomposition and does not have a spinodal structure. Furthermore, this material is intended for ease of blowing and high output during magnetic recording, and although it has a high magnetic permeability, it has a small coercive force. In contrast, the present invention aims at high-density recording, and it is necessary to reduce the magnetic permeability and increase the coercive force. This is because, in high-density recording, if the magnetic permeability is large, the demagnetizing field becomes large, which weakens the magnetization and reduces the output, which is inappropriate. In addition, at the state of the art at the time of filing the above patent, there was still no demand for high-density recording, and a medium with a maximum coercive force of about 2500e or less obtained from a cold-forged alloy after melting and quenching could be used satisfactorily. For high-density recording in the present invention, a coercive force of 5000e or more is required.
Such a coercive force was made possible for the first time by the workable magnet that utilizes spinodal decomposition in the present invention. The magnetic recording medium of the present invention will be explained in detail below. The magnetic recording body of the present invention is composed of an alloy thin plate having a thickness of 0.5 to 20 μm and having a composition represented by the above formula. That is, the alloy thin plate constituting the magnetic recording medium of the present invention has Cu, Ni, Fe, and Mn as essential components in its composition. Among these essential components, Fe
up to 50% by weight may be substituted with Co. In this case, as mentioned above, Cu, Ni and Fe
Alternatively, the Cu content x in the basic composition consisting of Fe and Co is 25 to 80% by weight, but more preferable results are obtained when it is 35 to 80% by weight. When x is less than 25% by weight, the coercive force Hc decreases, the amount of demagnetization increases,
When it exceeds 80% by weight, the residual magnetic flux density Br and Hc
decreases and the amount of demagnetization increases. Further, the Ni content y in these basic compositions is 10 to 40% by weight. When y is less than 10% by weight, Br and Hc decrease and the amount of demagnetization increases, and when it exceeds 40% by weight, Hc decreases and the amount of demagnetization also increases. Furthermore, the Fe content in the basic composition, or Fe and
The total content of Co, i.e. z, is 100−x−y% by weight
However, under these conditions, at least 5
% by weight, preferably 10% by weight or more. On the other hand, the Fe substitution amount v of Co is 0 to 50% by weight of the total amount of Fe and Co. 100-x-y is 5% by weight
If it is less than 20%, Br and Hc will decrease and the amount of demagnetization will increase. Moreover, when v is 0 to 50% by weight, Mn
The effect of the addition of is expressed, Br and Hc are improved,
It is sufficiently low for practical use, and the amount of demagnetization can be suppressed. Furthermore, in addition to the basic composition of Cu, Ni, Fe, and Co as necessary, the thin alloy plate constituting the magnetic recording medium of the present invention contains Mn, and its content q is 0.05 to 10% by weight of the whole. , more preferably
It is 0.1 to 5% by weight. When the Mn content q is larger than the upper limit and smaller than the lower limit, the residual magnetic flux density (Br), coercive force (Hc), squareness ratio (Br/Bs; Bs is the saturation magnetic flux density), etc. This is because the magnetic field decreases, making it unsuitable for high-output, high-density recording, and causing a large amount of demagnetization. Only within such a range of Mn content q can a magnetic recording medium suitable for high-output, high-density recording with a critically small amount of demagnetization be obtained, as will become clear from the Examples described later. On the other hand, the alloy thin plate constituting the magnetic recording body of the present invention contains one or more other additive elements M in addition to the essential components consisting of Cu, Ni, Fe, and Mn, and if necessary Co. You can leave it there. In this case, one or more of the other additive elements M include V, Si, B, Ti, Zr, Ta, Cr, Nb, W,
Preferably, one or more of transition metal elements such as Mo, A, group A elements, and the like can be mentioned. One or more of these other additive elements may be contained in the alloy in a total amount of 0 to 5% by weight. The alloy thin plate constituting the magnetic recording medium of the present invention has such a composition, but when viewed structurally, it essentially consists of a spinodal decomposition type structure. Spinodal decomposition is a form of precipitation hardening, and a spinodal decomposition type structure is described, for example, in the Bulletin of the Japan Institute of Metals, No. 12 (1973
2006), page 289, a structure in which a multidimensional alloy of supersaturated solid solutions separates into two phases, with only the concentration varying without nucleation. It is. The thin alloy plate constituting the magnetic recording medium of the present invention has such a structure and is therefore magnetically hardened. As a result of such spinodal decomposition, the alloy thin plate constituting the magnetic recording medium of the present invention is generally composed of particles having an anisotropic shape such as needle-like shapes with a particle size of about several hundred angstroms. On the other hand, the magnetic recording medium of the present invention is composed of a thin alloy plate having the above composition and structure and having a thickness of 0.5 to 20 μm. In this case, if the thin plate thickness is less than 0.5 μm, the manufacturing yield will deteriorate and the magnetic properties will deteriorate. Also, when making long magnetic tapes for use in audio, video, ultra-large capacity storage devices, etc., if the plate thickness is greater than 20 μm,
Due to the hardness of the alloy itself, the flexibility of the tape decreases, causing fluctuations in the tape running trajectory, worsening the stability of contact with the magnetic head when using a contact bed method, and reducing the flying clearance when using a floating head method. The gap stability will deteriorate, resulting in input/output fluctuations. In addition, the plate thickness is further reduced to 0.5
When it is in the range of ~10 μm, high frequency characteristics and F characteristics are improved, and it is possible to obtain characteristics comparable to those of conventional coated type magnetic recording media for various types of audio, video, etc. magnetic recording media. The magnetic recording body of the present invention is composed of such a thin alloy plate. Generally, it is used as a magnetic tape for various types of open reels, cassettes, cartridges, etc. for performing analog or digital magnetic recording. In this case, the magnetic tape can be constructed from such a thin alloy plate itself, or it can be made by pasting such a thin alloy plate to a flexible support such as polyethylene terephthalate having a thickness of about 5 to 20 μm. In addition, a magnetic tape can also be constructed using this. Furthermore, various magnetic sheets,
It can also be a magnetic recording medium such as a magnetic card, magnetic disk, magnetic drum, or magnetic scale. The magnetic recording material of the present invention described in detail above exhibits an extremely high coercive force, an extremely high residual magnetic flux density, and an extremely high squareness ratio (Br/Bs). Therefore, it is a high-density magnetic recording medium that has extremely high resolution and is suitable for extremely short recording wavelengths. Furthermore, extremely high output can be obtained and the S/N ratio is also extremely good. Since it is made of a thin alloy plate with a thickness of 0.5 to 20 μm, when it is used as a magnetic tape, it has good flexibility and extremely high stability in contact with the head and in the spacing. Furthermore, under such a premise, the magnetic recording body of the present invention is made of Cu--Ni containing a predetermined amount of Mn.
-Since it is made of an Fe-based alloy, the amount of demagnetization caused by various factors is much smaller than that of one that does not contain Mn. Such a magnetic recording body of the present invention is generally manufactured as follows. First, an alloy having a corresponding composition is thinned until it reaches a predetermined thickness, or approximately 100 times the predetermined thickness. In this case, first, Cu,
Ni and Fe and other predetermined amounts of additional elements as necessary are weighed and blended. Next, this is melted, for example, by high-frequency induction heating in a vacuum, and further cast, for example, in a vacuum. In this way, a cast master alloy is obtained, but depending on the mode of the magnetic hardening treatment described below or depending on the thickness of the master alloy, the master alloy may be directly subjected to the magnetic hardening treatment described below. You can also do it. In addition, when performing magnetic hardening treatment on the master alloy as it is in this way, it is preferable to previously perform solution treatment and warm forging prior to that. Such solution treatment is carried out by heating and holding at a temperature of 950 to 1050°C, for example, for about 30 minutes to 30 hours, and the treatment atmosphere may be in air, but it is Preferably, the reaction is carried out under an active, non-oxidizing or reducing atmosphere. Further, the subsequent warm casting may be performed at a temperature of, for example, about 200-500°C. However, usually the master alloy as described above is made even thinner. As for this kind of thinning,
Rolling can be used. In this case, rolling is
It may be carried out cold or warm. Then, this rolling can be performed until the rolling ratio (rolling reduction ratio) becomes approximately 99 to 99.9%. In this case, it is preferable that the cast master alloy is sequentially subjected to solution treatment and warm casting in advance as described above. Alternatively, the master alloy obtained as described above can be used to directly form a thin plate according to a so-called liquid cooling method. In this case, the master alloy is melted in a heating tube to form a melt, the melt is jetted from a nozzle of the heating tube, and the melt is rotated in various ways, such as by single roll, twin roll, inside-in die exion method, etc. Contact with cooling body. As a result, the melt is cooled at a cooling rate of, for example, about 10 ² °C/sec or higher, solidified, and is itself made into a thin plate and drawn out as a long thin plate. Note that the alloy thinned by the liquid cooling method as described above may be further subjected to a rolling treatment as described above. Next, the alloy thus thinned is subjected to spinodal decomposition and subjected to a treatment to cause magnetic hardening. Such steam hardening treatment involves heating the thinned alloy at, for example, 550 to 650°C for 30 minutes to 10 minutes.
Aging may be simply performed by heating and holding in a non-magnetic field for about an hour and then slowly cooling. However, such aging is performed by heating and holding at 550 to 650°C in a non-magnetic field for about 30 minutes to 10 hours, and then slowly cooling it until the temperature drops to about 400 to 450°C. , for example, by performing multi-stage aging in increments of 10 to 50°C and holding each temperature for about 30 minutes to 50 hours, or from the above temperature at a cooling rate of, for example, about 0.5 to 20°C/hr. It is preferable to perform continuous aging while slowly cooling. In this case, such magnetic hardening treatment includes:
When the spinodal decomposition particles are precipitated or at a certain period after the particles are precipitated, a predetermined treatment is added to increase the shape anisotropy of the precipitated particles. This results in a structure consisting of alignment, resulting in more favorable results in terms of magnetic properties. One way to increase the shape anisotropy is to carry out aging in a magnetic field at the initial stage of the magnetic hardening process. In this case, aging in a magnetic field, which is performed as a preliminary step, may not be possible depending on the alloy composition, but for alloys with a Curie point above a certain value and a composition that can be treated in a magnetic field. This is an effective means for improving magnetic properties. If such aging in a magnetic field is possible, in the aging carried out in various ways as described above,
At least the statute of limitations in the initial or early stages,
For example, it may be performed while applying a magnetic field of about 1,000 to 30,000 e. However, such aging in a magnetic field is often not possible due to the Curie point temperature of the alloy, depending on the alloy composition. For this reason, it is preferable to use rolling as a means for increasing the shape anisotropy. In this case, generally, after pre-aging in a non-magnetic field at a temperature of 550 to 650°C for about 30 minutes to 10 hours, further rolling is performed, which makes the particles larger after precipitation. It is preferable to adopt a mode in which shape anisotropy is imparted, the thin plate is made to a final predetermined thickness, and then post-aging is performed again in a non-magnetic field. In such cases, the rolling is usually performed at a cold rolling rate (reduction rate) of, for example, 99%.
This can be carried out until the thickness is about 99.9%, thereby making the thin plate the final desired thickness. Although the pre-aging may be carried out in a magnetic field, it is usually sufficient to perform it in a non-magnetic field, and the post-aging may be carried out in a multi-stage or while cooling with the temperature profile described above. It is preferable to carry out continuous aging. The aging in a magnetic field or in a non-magnetic field can be carried out in air, but it is preferably carried out in a vacuum, inert, non-oxidizing or reducing atmosphere. The thin alloy plate of the present invention, which is a workable magnet utilizing spinodal decomposition, obtained in this way is then formed into a predetermined shape and size, bonded to a support as necessary, further subjected to predetermined processing, and subjected to various It is considered a magnetic recording medium. The magnetic recording body of the present invention is manufactured in this way, and the magnetic recording body of the present invention exhibits the excellent performance described above. Furthermore, since the alloy thin plate constituting the magnetic recording medium of the present invention is itself manufactured as a thin plate, productivity is high and there is little variation in quality. Furthermore, a predetermined amount of
As a result of including Mn, there are manufacturing advantages in that the master alloy can be easily cast, and subsequent rolling etc. can also be facilitated. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 A predetermined amount of Mn was added to a predetermined amount of a mixture of 60 wt% Cu, 20 wt% Ni, and 20 wt% Fe, and each element was blended so that the Mn content was as shown in Table 1 below. did. This was melted by high-frequency induction heating under vacuum, and then cast to create a master alloy. Next, using the master alloy thus obtained, it was made into a thin plate according to a liquid cooling method. That is, the master alloy is melted by high-frequency induction heating in an argon atmosphere to form a melt, pressurized with argon gas, and the melt is blown onto the surface of a single roll cooling body at a cooling rate of about 10 ³ °C/sec. It was cooled and solidified to obtain a long thin plate with a thickness of 200 μm. Next, the thus obtained thin plate was aged in a vacuum at 580°C for 1 hour in the absence of a magnetic field.
Thereafter, cold rolling was performed at room temperature to form a thin plate with a thickness of 4 μm. Furthermore, after this, the material was heated and held at 580° C. for 1 hour in a vacuum, and then multistage aging was performed in a non-magnetic field while cooling from 580° C. in this case,
In multi-stage aging, each time the temperature drops by 20 degrees Celsius, the temperature is stagnated for 1 to 10 hours, and as the temperature decreases, this stagnation time is lengthened, and finally, when the temperature drops to 460 degrees Celsius. This was done by holding for 10 hours and then cooling. The four types of thin plates thus obtained were slit to a predetermined width to produce audio cassette tapes. These four types of cassette tapes were heated at 100℃ for 100 hours and subjected to self-demagnetization acceleration tests.
When the fluctuation rate (%) of the output level at 333 Hz was measured, the results shown in Table 1 below were obtained. Separately, the output level (MML) at 333Hz with 3% third harmonic distortion and the saturated output level (MOL) at 14kHz were measured for four types of cassette tapes. On the other hand, the coating layer thickness using γ-Fe ₂ O ₃ +Co as magnetic powder
The MML and MOL of a commercially available 6μm chrome position type cassette tape were measured.
When the output level difference (dB) between this and the four types of cassette tapes mentioned above was determined, the results shown in Table 1 were obtained. Furthermore, each cassette tape was run for a predetermined length and a 10kHz signal was recorded and played back, and the playback level fluctuation rate (dB) at that time was measured, as shown in Table 1.
We obtained the results listed below.

[Table] Although a thin plate with a Mn content of 12% was obtained in the same manner as above, it was found that the output was low and could not be put to practical use. From the above results, when containing 0.05 to 10% by weight of Mn, the amount of demagnetization is significantly smaller than when containing no Mn, and moreover, when the Mn content is 0.1 to 5% by weight.
It can be seen that when this is the case, a magnetic tape with high output and better high-frequency characteristics can be obtained. Example 2 In Example 1, Cu60% by weight therein,
The total of Ni20wt% and Fe20wt% is 98wt%,
For a 4 μm thick ferromagnetic alloy conductive plate containing 2% by weight of Mn, only the rolling ratio in the magnetic hardening treatment was varied to obtain three types of alloy thin plates with thicknesses of 4 μm, 15 μm, and 25 μm, and then Examples Similar to Example 1, three types of cassette tapes were obtained. Next, the level difference (dB) of 333 Hz MML and 14 kHz MOL between each cassette tape and the conventional coated tape was determined in the same manner as in Example 1, and the results shown in Table 2 below were obtained. Furthermore, as in Example 1, these three types of cassette tapes were recorded and played back at 10kHz for a predetermined length, and the playback level fluctuation rate (dB) at that time was measured to evaluate the running performance.Table 2 We obtained the results listed below.

[Table] These three types of cassette tapes having different thicknesses showed almost the same amount of demagnetization as a result of the same accelerated demagnetization test as in Example 1. From these results, when the plate thickness is greater than 20 μm, the playback level fluctuation rate increases and the head contact is poor, making it unusable for practical use.
It can be seen that a sufficiently good reproduction level fluctuation rate can be obtained with the thickness below. On the other hand, when the thickness is greater than 20 μm, the high frequency characteristics are extremely poor, whereas when the thickness is less than 20 μm, especially less than 10 μm,
It can be seen that extremely excellent high-frequency characteristics can be obtained. Example 3 A 4 μm thick alloy thin plate having the composition shown in Table 3 below was prepared in the same manner as in Example 1, and used as a cassette tape.
We measured the 10kHz MOL difference and the 10kHz playback level fluctuation rate. The results are shown in Table 4.

【table】

[Table] From the results in Table 4, the effect of adding Mn to the alloy thin plate is clear.

Claims (1)

[Scope of Claims] 1. A magnetic recording medium comprising a processable magnet using spinodal decomposition, containing a composition represented by the following formula as a main component, and comprising a thin plate having a thickness of 0.5 to 20 μm. Formula [Cu _x Ni _y (F _u Co _v ) _z ] _p Mn _q [wherein, the sum of x, y, and z is 100% by weight,
x is 25 to 80% by weight, y is 10 to 40% by weight, and z is 100-xy% by weight, but never less than 5% by weight. Further, the sum of u and v is 100% by weight, and v is 0 to 50% by weight. Furthermore, p
The sum of and q is 100% by weight, and q is 0.05 to 10% by weight. ]