JP2022547963A - Magnetic recording tape with elastic substrate - Google Patents

Abstract

A magnetic recording tape according to one approach includes a substrate comprising polyetheretherketone (PEEK). An underlayer is disposed over the substrate. A recording layer is disposed on the lower layer.

Description

The present invention relates to magnetic recording media and, more particularly, to various configurations of substrates for magnetic recording tape media.

In magnetic storage systems, magnetic transducers read data from and write data to magnetic recording media. Data is written to a magnetic recording medium by moving a magnetic recording transducer to a location on the medium where the data is stored. The magnetic recording transducer then generates a magnetic field that encodes the data and writes it to the magnetic medium. Data is read from the medium by similarly placing a magnetic read transducer and then sensing the magnetic field of the magnetic medium. Read and write operations can be independently synchronized with movement of the media to ensure that data can be read from and written to desired locations on the media. .

A continuing and important goal of the data storage industry is to increase the density of data stored on media. For tape storage systems, this goal has led to increased track and linear bit densities on recording tapes and reduced thicknesses of magnetic tape media. However, the development of smaller footprint, higher performance tape drive systems presents a variety of challenges, ranging from designing tape head assemblies for use in such systems to dealing with tape dimensional instability. produced.

One challenge that arises with increasing track and data densities and that is increasingly limiting formats is tape dimensional stability, particularly lateral dimensional stability. Lateral shrinkage and expansion of tapes are well-known phenomena caused by numerous effects, including water absorption, thermal expansion and contraction, and the like. A change in tape width results in the overwriting of previously written data tracks when performing shingled writing and the inability to read from data tracks that are no longer aligned with the reader. (This is especially prevalent in tracks near the outer edge of the reader array), and many other disadvantages can occur.

More permanent changes in media lateral dimensions can also occur, such as long-term media creep (also known in the art as "aging"). Long-term media creep tends to occur over time when the tape is wrapped around the hub of the tape cartridge. Long-term media creep is particularly problematic when addressing tape dimensional stability issues. This is because the two ends of the tape exhibit different modes of creep. The inner wrap of tape located closest to the cartridge hub tends to shift laterally over time due to the compressive stresses exerted on the inner wrap by the wrap of tape wrapped around the inner wrap. tends to swell. Wraps located near the outer diameter of the spool of tape are under less compressive stress, but are subject to greater tensile stress, which tends to cause lateral shrinkage of the tape. That is, the width of the tape becomes smaller over time. Therefore, the ends of the tape tend to exhibit opposite lateral dimensional changes.

Various problems arise when the dimensions of the tape change. Increased chances of overwriting a shingled track during writing. Overwritten data is often unrecoverable. Similarly, if the tape width changes after the desired data is written, the reader may no longer be positioned over the track to be read, thereby increasing read errors.

The substrate is usually the thickest layer in a magnetic recording tape and therefore tends to have the greatest effect on the lateral stability of the tape. Stated another way, the substrate tends to dominate the overall laminated tape structure with respect to dimensional changes.

Current magnetic recording tape substrate materials such as polyethylene naphthalate (PEN) and aramid suffer from poor tape dimensional stability (TDS), sensitivity to humidity, poor creep recovery or other There are a variety of problems, including shortcomings, or combinations thereof, that make current magnetic recording tape substrate materials meet the demand for magnetic recording tapes with higher data densities than are currently commercially available. There is no such thing.

Current substrates have reached the limit of possible modifications to improve the substrate's sensitivity to water and temperature and to solve the problems mentioned above.

Therefore, there is a need in the art to solve the above problems.

Viewed from a first aspect, the present invention provides a magnetic recording tape comprising a substrate comprising polyetheretherketone (PEEK) and an underlayer over the substrate. (underlayer) and a recording layer above the underlayer.

Viewed from an additional aspect, the present invention provides a tape cartridge comprising a housing and a magnetic recording tape at least partially contained within the housing, the magnetic recording tape comprising: , a substrate comprising polyetheretherketone (PEEK), an underlayer over the substrate, and a recording layer over the underlayer.

Viewed from an additional aspect, the present invention provides a method of manufacturing a magnetic recording tape, the method comprising bonding an underlayer to a substrate, the substrate comprising polyetheretherketone (PEEK).

Viewed from an additional aspect, the present invention provides a method of manufacturing a magnetic recording tape, the method comprising, by radiation-induced grafting, a substrate comprising polyetheretherketone (PEEK). Bonding the underlayer and bonding the recording layer to the underlayer.

A magnetic recording tape according to one approach includes a substrate comprising polyetheretherketone (PEEK). An underlayer is disposed over the substrate. A recording layer is disposed on the lower layer.

Magnetic recording tapes with PEEK substrates have excellent resilience for normal tape operation and exhibit stable creep and recovery for normal storage and operating temperatures from about 0°C to about 60°C. The shrinkage of the PEEK substrate is expected to be less than 1% over a temperature range of 100°C, including the operating range mentioned above. Such advantages are achieved in a preferred approach wherein the PEEK chain length is greater than about 20, more preferably the PEEK has a chain length of about 50 to about 100.

Magnetic recording tapes with PEEK substrates also have low sensitivity to temperature and humidity throughout this operating range. PEEK is generally hydrophobic, which makes it stable to water. Water absorption is expected to be much less than 1% at 50% relative humidity, much lower than aramid, which tends to have a water absorption of about 10% at 50% relative humidity.

Magnetic recording tapes with PEEK substrates have stable mechanical properties. For example, tensile storage (E') modulus and tensile loss ( E"") Both moduli are lower than the base material of conventional media. In one aspect, the substrate has a tensile storage (E') modulus measured by dynamic thermomechanical analysis in the range of about 4 GPa to about 20 GPa.

An additional advantage of PEEK is that the PEEK raw material can be melted without degradation, which makes it possible to process PEEK into thin films at temperatures near its melting point without losing its desirable properties. to enable.

In one aspect, the underlayer is grafted onto the substrate. The graft, as a result, provides a stronger bond between the layers than conventional bonding techniques. This is advantageous with respect to robustness and resistance to stress.

Each of the above is important for maintaining dimensional stability both during use and long-term storage.

A tape cartridge according to one aspect includes a housing and a magnetic recording tape at least partially enclosed within the housing. A magnetic recording tape has the structure described above.

Other aspects and techniques of the invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrates the principles of the invention.

The invention will now be described, by way of example only, with reference to preferred embodiments shown in the following figures.

1 is a schematic diagram of a simplified tape drive system; FIG. 1 is a schematic diagram of a tape cartridge according to one aspect of the present invention; FIG. 1 is a side view of a flat-lapped, bi-directional, two-module magnetic tape head according to one aspect of the present invention; FIG. Figure 2B is a view of the tape support surface taken from line 2B of Figure 2A; Figure 2C is a detail view taken from circle 2C of Figure 2B; FIG. 4 illustrates a tape layout according to one approach; FIG. 4 illustrates a hybrid servo pattern written to a dedicated area of tape media, according to one approach. FIG. 4 is a partial detail view of a TBS pattern according to one approach; FIG. 4 is a partial top view showing the effects of tape expansion and contraction; FIG. 4 is a partial top view showing the effects of tape expansion and contraction; FIG. 4 is a partial top view showing the effects of tape expansion and contraction; 1A and 1B are partial cross-sectional views of basic structures of magnetic recording media according to various techniques; Dynamic mechanical thermal analysis (DMTA) results for the current tape substrate example to obtain the tensile storage modulus (E') in gigapascals (GPa) over a temperature range were measured at a thickness of 8 microns. and a PEEK film. Figure 8 is a graph showing the data of Figure 7 over a temperature range of 0°C to 60°C; FIG. 3 illustrates exemplary PEEK according to various techniques; FIG. 3 illustrates exemplary PEEK according to various techniques; FIG. 3 illustrates exemplary PEEK according to various techniques; FIG. 3 illustrates exemplary PEEK according to various techniques;

The following description is written to illustrate the general principles of the invention and is not intended to limit the inventive concepts described herein. Also, certain features described herein may be used in combination with other features described in each of the various combinations and permutations possible.

Unless otherwise defined herein, all terms include the meaning implied from this specification and/or the meaning understood by those skilled in the art or defined in dictionaries, academic literature, etc. , given its broadest possible interpretation.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" also include plural referents unless explicitly stated otherwise. must be kept in mind.

The following description discloses various configurations of substrates that are particularly useful in magnetic recording tape media, as well as methods of forming the substrates and magnetic recording tape media.

In one general approach, a magnetic recording tape includes a substrate comprising polyetheretherketone (PEEK). An underlayer is disposed over the substrate. A recording layer is disposed on the lower layer.

In another general approach, a tape cartridge includes a housing and magnetic recording tape at least partially enclosed within the housing. A magnetic recording tape has the structure described above.

Exemplary Operating Environment FIG. 1A shows a simplified tape drive 100 of a tape-based data storage system that can be used in connection with the present invention. Although one particular implementation of a tape drive is shown in FIG. 1A, the techniques described herein can be implemented in connection with any type of tape drive system. should be noted.

As shown, tape supply cartridge 120 and take-up reel 121 are provided to support tape 122 . One or more of these reels may form part of a removable cartridge and need not be part of tape drive 100 . A tape drive, such as the tape drive shown in FIG. - can include a motor; Such a head may include an array of readers or an array of writers, or both.

Guides 125 guide tape 122 across tape head 126 . Such tape heads 126 are coupled to controller 128 via cables 130 . Controller 128 may be or include a processor and/or any logic for controlling any subsystem of drive 100 . For example, controller 128 typically controls head functions such as servo following, data writing, and data reading. Controller 128 may include at least one servo channel and at least one data channel, each of which processes or stores information to be written to and/or read from tape 122. or data flow processing logic configured to both process and store. The controller 128 may operate under logic known in the art and disclosed herein, thus controlling the tape in the various techniques included herein. - With respect to any of the drive descriptions, the controller 128 can be considered a processor. Controller 128 may be coupled to any known type of memory 136 , which may store instructions executable by controller 128 . Further, controller 128 may be configured to perform or control some or all of the methods presented herein, or be programmable to perform or control them. can be, or can be both. Thus, controller 128 may be logic programmed into one or more chips, modules or blocks, or combinations thereof; software, firmware, or other instructions available to one or more processors, or combinations thereof; etc., and combinations thereof, can be considered configured to perform various operations.

Cable 130 may include read/write circuitry for transmitting data to tape head 126 for recording on tape 122 and for receiving data from tape 122 read by tape head 126 . Actuator 132 controls the position of tape head 126 relative to tape 122 .

In addition, for communication between the tape drive 100 and the host (internal or external) for sending and receiving data, and for controlling the operation of the tape drive 100 and communicating the status of the tape drive 100 to the host. can be provided with an interface 134 . All of these will be understood by those skilled in the art.

FIG. 1B illustrates an exemplary tape cartridge 150, which in various approaches can include any configuration of magnetic recording media described herein in the form of tape. . Such tape cartridges 150 can be used with systems such as the system shown in FIG. 1A. As shown, tape cartridge 150 includes housing 152 , tape 122 within housing 152 , and optional non-volatile memory 156 coupled to housing 152 . In some approaches, non-volatile memory 156 can be embedded inside housing 152, as shown in FIG. 1B. In more approaches, non-volatile memory 156 can be mounted inside or outside housing 152 without modifying housing 152 . For example, non-volatile memory can be embedded in the adhesive label 154 . In one preferred approach, non-volatile memory 156 is solid-state memory (e.g., flash memory), read-only memory, embedded inside or outside tape cartridge 150, or coupled inside or outside tape cartridge 150. It may be a memory only (ROM) device, or the like. This non-volatile memory can be accessed by the tape drive and tape operating software (driver software), another device, or a combination thereof.

By way of example, FIG. 2A shows a side view of a flat-wrap, bi-directional, two-modular magnetic tape head 200 that can be implemented in conjunction with the present invention. As shown, the head includes a pair of bases 202, each with a module 204, fixed at a small angle α to each other. These bases can be "U-beams" that are glued together. Each module 204 includes a substrate 204A and a closure 204B having a thin film portion commonly referred to as a "gap" with a reader and/or writer 206 formed therein. In use, tape 208 is moved along media (tape) support surface 209 over module 204 as shown to read and write data on tape 208 using a reader and writer. Let The wrap angle θ of the tape 208 at the edge that rests on the flat media support surface 209 and exits the support surface 209 is typically between about 0.1 degrees and about 3 degrees.

Substrate 204A is typically constructed of a wear resistant material such as ceramic. Closure 204B can be made of the same ceramic as substrate 204A or the same type of ceramic as substrate 204A.

Readers and writers can be arranged in a piggyback or merged configuration. An exemplary piggyback configuration comprises a (magnetically inductive) writer transducer above (or below) a (magnetically shielded) reader transducer (such as a magneto-resistive reader), with the writer pole and the reader shield The body is generally separated. An exemplary merged configuration comprises one reader pole in the same physical layer as one writer pole (hence the term "merged"). Readers and writers can also be arranged in an interleaved configuration. Alternatively, each array of channels can be readers only or writers only. Any of these arrays may include one or more servo track readers for reading servo data on the media.

FIG. 2B shows tape support surface 209 of one module 204 taken from line 2B of FIG. 2A. A typical tape 208 is shown in dashed lines. Module 204 preferably has sufficient length to support the tape as the head steps between data bands.

In this example, the tape 208 contains 4 to 32 data bands, for example, 16 data bands on a 1/2 inch wide tape 208 as shown in FIG. 2B. data band and 17 servo tracks 210 . Data bands are defined between servo tracks 210 . Each data band may contain several data tracks, for example 1024 data tracks (not shown). During read/write operations, a reader and/or writer 206 is positioned at a particular track location within a data band. An outer reader, sometimes called a servo reader, reads servo tracks 210 . These servo signals are then used to keep the reader and/or writer 206 aligned with a particular set of tracks during read/write operations.

FIG. 2C shows multiple readers and/or writers 206 formed in gaps 218 on module 204 in circle 2C of FIG. 2B. As shown, the array of readers and writers 206 includes, for example, 16 writers 214, 16 readers 216 and 2 servo readers 212, although the number of elements may vary. Exemplary approaches include 8, 16, 32, 40 and/or 64 active readers or writers 206 per array, or an interleaved design with an odd number of readers or writers such as 17, 25, 33. including. One exemplary approach includes 32 readers per array and/or 32 writers per array, where the actual number of transducer elements is greater than 32, such as 33, 34, etc. can do. This means that the tape moves more slowly, thereby reducing velocity-induced tracking and mechanical difficulties, or that the tape performs fewer "wraps" to fill or read the tape; Or allow both. Readers and writers can be arranged in a piggyback configuration as shown in FIG. 2C, although readers 216 and writers 214 can also be arranged in an interleaved configuration. Alternatively, each array of readers and/or writers 206 can be either only readers or only writers, and an array can include one or more servo readers 212 . 2A and 2B-2C together, it will be noted that each module 204 has a complementary set of readers or writers or Both 206 can be included.

Timing-based servo write and read elements allow magnetic regions of the recording layer of a magnetic recording tape to be magnetized to form bits of magnetic segments. The bits appear as rectangular sections that display an increased or decreased magnetic signal when detected by a magnetically susceptible detector such as a magnetic force microscopic (MFM) detector.

Placing data on separate tracks requires real-time location information regarding the location of written information residing on the tape to prevent accidental erasure of previously written information. When data is first written to a formatted tape on which no data has been written, ensure that subsequent data bands are correctly written so as not to overwrite or corrupt previously written data. The position of the first data band must be carefully controlled and recorded in order to be able to position .

Modern high density tape formats use very precise servo patterns known to those skilled in the art called timing-based servos. A description of an exemplary timing-based servo scheme is provided below.

This track following servo includes transitions recorded in two or more azimuthal orientations across the width of the servo track. A signal derived by reading at any point across the width of a written pattern created on tape media in a controlled, precision factory formatting operation to calculate the position of the magnetic recording head in real time. timing is used. This pattern is read by a servo reader that has a width that is small compared to the width of the servo track. The combination of wide servo patterns and narrow servo readers provides excellent position sensing linearity and dynamic range.

Position sensing using a timing-based servo system is achieved by deriving the ratio of two servo pattern intervals and is therefore insensitive to tape speed during readback of recorded signals. . Detection of the center of the servo pattern during tape motion provides an accurate reference point for each data band. The difference between the centers of the two servo readers used in each read or write motion of the tape across the recording head is a measure of the spacing between two servo bands on the tape previously recorded during factory formatting. be. The servo reader is fixed within the head structure but moves on very small nanometer scales due to stress and environmental factors. Thus, the actual positions of the intervals between servo bands written on the tape move relative to each other, resulting in preexisting or written over existing data tracks. The actual spacing between data bands changes.

Referring briefly to FIG. 3, an exemplary tape layout according to one approach is shown. As shown, tape 300 has five servo bands, servo band 0, as specified in the LTO (LTO is a trademark of HP. IBM Corp. Quantum) and IBM® Enterprise formats. . . . have a tape layout that implements servo band 4 and 4 data bands, namely data band 0 through data band 3; IBM is a trademark of International Business Machines Corporation, registered in many jurisdictions worldwide. The height H of each servo band is measured in a cross-track direction 304 generally perpendicular to the length L of tape 300 . According to one example, the height H of each servo band can be approximately 186 microns according to the LTO format. Further, the pitch β between the illustrated servo bands can be approximately 2859 microns, also according to the LTO format.

Also shown is an exemplary tape head 302 having two modules and positioned over a portion of tape 300 according to one approach. Read and/or write transducers may be placed in any module of tape head 302 according to any of the techniques described herein, and the read and/or write transducers may be used. can read data from and/or write data to the data band. Further, in accordance with any of the techniques described herein, tape head 302 can include servo readers that can be used to read the servo patterns of the servo bands. can. It should also be noted that the dimensions of the various components included in FIG. 3 are provided by way of example only and are in no way intended to limit the invention.

Some tape drives may be configured to operate at low tape speeds or nanometer head positioning, or both. These tape drives target barium ferrite (BaFe) tape media, 4 or 8 data bands, 32 or 64 data channel operation, allow very low speed operation, and large bandwidth actuator operation. and improves parameter estimation to minimize the standard deviation of the position error signal (PES), thereby enabling track density scaling for tape cartridge capacities of 100 TB or greater. format can be used.

However, according to some approaches, magnetic tape can be further enhanced with additional features that provide additional functionality. Accordingly, an HD servo pattern can be implemented instead of the standard TBS servo pattern, eg, as shown in FIG. This HD servo pattern can be used to improve track following performance.

In yet another approach, a standard TBS servo pattern (eg, as shown in FIG. 3) can be implemented in combination with one or more HD servo patterns (see, eg, FIG. 4A below). One embodiment includes a hybrid servo pattern scheme in which the standard TBS pattern is maintained and additional HD patterns are provided in dedicated areas of the tape media, preferably dedicated areas not currently in use. In some approaches, this type of pattern can be implemented by increasing the number of data channels from 16 to 32 and reducing the width of the TBS pattern from 186 microns to 93 microns.

FIG. 4A shows a hybrid servo pattern 410 that includes a standard TBS pattern 402 written on a servo band of tape medium 408 and an HD pattern 404 written on an HD band (eg, a dedicated area). Further, each HD pattern 404 includes several HD tracks, each HD track having its own periodic waveform. In some approaches, important features of the original TBS pattern 402 are preserved, such as the servo frame structure consisting of four servo bursts containing several servo stripes. In these servo bursts, the servo stripes of adjacent servo bursts are written at alternating azimuth angles. Other parameters of conventional servo patterns, such as the height and other geometric dimensions of the servo patterns and the number of servo stripes per burst, can be varied as desired.

The HD pattern 404 may comprise periodic waveforms of varying frequencies written alternately lengthwise L along the longitudinal axis of the tape. Initial identification of servo bands (e.g., by providing a servo band ID) using standard TBS pattern 402; initial positioning of head 406 to appropriate servo position; tape velocity, head lateral position; , head-tape skew, obtaining initial servo channel parameters such as longitudinal position (LPOS); In addition, HD pattern 404 can enable more accurate and more frequent estimation of servo channel parameters, thereby resulting in improved head positioning over a much wider range of tape speeds and greater bandwidth. support for head actuation can be achieved. As such, track density scaling to very large cartridge capacities can be enabled, and support for a wider range of speeds can improve data rate scaling with host computer requirements.

Referring again to FIG. 4A, which shows a tape layout 400 having a hybrid servo pattern 410 according to one approach, within the hybrid servo pattern 410 an HD pattern 404 is written in the space next to the standard TBS pattern 402. . According to this approach, the quadrature sequence is not included because the TBS pattern 402 is used. This is in contrast to products that implement servo functions in hard disk drives.

Referring now briefly to FIG. 4B, a partial detail view of a TBS pattern 402 (eg, a TBS frame) is shown according to one exemplary approach. As shown, a plurality of servo stripes 412 form servo bursts 414 and corresponding pairs of servo bursts 414 form servo subframes. Thus, the TBS frame shown has four servo bursts 414 and two servo subframes. In this approach, the servo bursts 414 contained in the left servo subframe each have five servo stripes 412, and the servo bursts 414 contained in the right servo subframe each have four servo stripes. It has stripes 412 . The servo stripes 412 in a given servo burst 414 are oriented such that the azimuth gradients of the servo stripes 412 represented by the angle α are the same. In addition, corresponding pairs of servo bursts 414 have opposite azimuthal gradients, thereby forming a chevron-type pattern. The height H and thickness t of servo stripes 412 may vary depending on the servo writer used to write TBS pattern 402 . According to one exemplary approach, which is not intended to limit the invention in any way, the height H can be about 186 μm, the angle α about 6°, and the thickness t about 2.1 μm. Further, the spacing S between each servo stripe 412 or the distance d between servo bursts 414 having the same azimuthal gradient or both may vary depending on the desired approach. According to one exemplary approach, which is not intended to limit the invention in any way, the spacing S can be approximately 5 μm and the distance d is approximately 100 μm. As described above, transitions according to a pattern such as that shown in FIG. 4B enable determination of an estimated head lateral position, which determination of the estimated position of the head lateral position is performed by servo bursts. This is done by evaluating the relative timing of the pulses generated by the servo readers that read the servo stripes 412 of 414 as they passed over the servo reader.

Tape Dimensional Stability Issues FIGS. 5A-5C illustrate the effect of lateral expansion and contraction of the tape on transducer array position relative to the tape and are in no way intended to limit the invention. do not have. FIG. 5A shows transducer array 500 against tape 502, which has a nominal width. As shown, transducers 504 are conveniently aligned with data tracks 506 on tape 502 . However, FIG. 5B shows the effect of lateral shrinkage of the tape. As shown, shrinkage of the tape also causes the data tracks to shrink, so that the outermost transducers 505 are positioned along the outer edges of the outer data tracks. Additionally, FIG. 5C illustrates the effect of lateral expansion of the tape. In this figure, the expansion of the tape has increased the distance between the data tracks so that the outermost transducers 505 are positioned along the inner edges of the outer data tracks. If the lateral contraction of the tape is greater than that shown in FIG. 5B, or if the lateral expansion of the tape is greater than that shown in FIG. , thereby overwriting adjacent tracks during a write operation or reading back the wrong track during a readback operation, or both. In addition, travel-related effects such as tape skew and lateral shift can exacerbate such problems, especially for tapes with single data tracks.

Thus, lateral expansion and contraction of tape is an ongoing challenge in tape development and remains a limiting factor in further increasing data density on tape.

Fabrication of Magnetic Recording Medium and Layers Thereof FIG. 6 shows a partial cross-sectional view of the basic structure of a magnetic recording medium 600 according to various techniques described herein. This figure is not drawn to scale. Optionally, this magnetic recording medium 600 can be implemented with features of other approaches described herein, such as features described with respect to other figures. It should be appreciated, however, that such magnetic recording medium 600 and other magnetic recording media presented herein may or may not be explicitly stated in the exemplary approach described herein. may be used in various applications or permutations or combinations thereof. Moreover, the magnetic recording medium 600 presented herein can be used in any desired environment. The various permutations of magnetic recording media 600 disclosed herein have been developed to improve the stability and performance of tape storage media throughout the environments in which they are used and stored.

Except where stated otherwise herein, the various layers of magnetic recording medium 600 can have conventional structures, designs or functions, or combinations thereof. New novel layers can be used along with conventional layers in a variety of approaches. Additional approaches may use a number of new novel layers along with other conventional layers.

Except where stated otherwise herein, the various layers of magnetic recording medium 600 are fabricated using conventional methods, particularly when each layer has a conventional structure. can be formed.

Magnetic recording medium 600 is preferably a magnetic recording tape, but in other aspects magnetic recording medium 600 is a different type of medium that is capable of being deformed.

As shown in FIG. 6, there are typically four basic layers in magnetic recording medium 600 . An optional backcoat 602 is disposed along one side (bottom side in FIG. 6) of substrate 604 . A bottom layer 606 is disposed along another side of the substrate 604 (the top side in FIG. 6). A recording layer 608 is disposed over the lower layer 606 . Additional layers of conventional construction may be present in the magnetic recording medium 600 in various ways.

Backcoat Backcoat 602 may or may not be present in magnetic recording medium 600 . The backcoat 602 can be made of known materials and can be selected as materials that can be grafted to the substrate 604 by radiation-induced grafting. The backcoat 602 is preferably constructed from a material that provides one or more of the following advantages: separation from separate sections of tape wrapped over the backcoat on the spool; Facilitate, improve tribology, dissipate static electricity, etc. A preferred thickness for the backcoat 602 is less than about 0.3 microns, preferably less than about 0.2 microns.

Substrate Substrate 604 has a new novel structure disclosed herein. Base material 604 is formed of polyetheretherketone (PEEK). As used herein, PEEK is more broadly referred to in the art as PEEK materials generically, including various types of polyaryletherketones (PAEK), polyetheretherketones and other like materials. Refers to a known type of material.

A magnetic recording tape with PEEK substrate 604 has stable mechanical properties. Tensile storage (E′) modulus and tensile loss (E″″) modulus measured for normal operating and storage environments of tape media using dynamic mechanical analysis methods such as dynamic mechanical thermal analysis (DMTA) are both lower than conventional media substrates. In general, normal operating and storage environments for tape media range from about 0° C. to about 60° C. and relative humidity from about 5% to about 80%.

A magnetic recording tape with PEEK substrate 604 also has low sensitivity to temperature and humidity throughout this operating range. PEEK is generally hydrophobic, which makes it stable to water. Water absorption is expected to be much less than 1% at 50% relative humidity, much lower than aramid, which tends to have a water absorption of about 10% at 50% relative humidity.

Magnetic recording tapes with PEEK substrate 604 also have excellent resilience for normal tape operation and exhibit stable creep and recovery for normal storage and operating temperatures of about 0°C to about 60°C. The shrinkage of the PEEK substrate is expected to be less than 1% over a temperature range of 100°C, including the operating range mentioned above.

An additional advantage of PEEK is that the PEEK raw material can be melted without degradation, which makes it possible to process PEEK into thin films at temperatures near its melting point without losing its desirable properties. to enable.

Each of the above is important for maintaining dimensional stability both during use and long-term storage.

PEEK has never been considered a suitable material for use in magnetic recording tape, as it has been focused on use in capacitors and other applications. PEEK has also never been one of the materials used for other applications by manufacturers of tape media substrates. Furthermore, conventional wisdom in attempting to improve the dimensional stability of tape media to cope with tape width variations and thus data track placement stability is based on the lateral (TD) stiffness of the substrate or The goal was to increase the modulus of elasticity. However, in the process, the composition of conventional substrates must be adjusted to achieve an increase in the TD modulus of the substrate. Thus, the inventive findings disclosed herein regarding the use of PEEK as a substrate material go in the opposite direction of conventional wisdom.

FIG. 7 shows the DMTA results for the current tape substrate example to obtain the tensile storage modulus (E') expressed in GPa over one temperature range, provided by Shin Etsu, Ltd.; (DMTA@10 Hz) compared to an 8 micron thick PEEK film. The current tape substrates used in this experiment are TORAY Spartan™, a blend of polyethylene terephthalate (PET) with chopped modified aramid (Mictron); TM), and TEIJEN Ltd. TD Tensilized PEN.

Graph 800 of FIG. 8 further extends this comparison over the temperature range (0° C. to 60° C.) in which tapes are typically used and stored. Only two substrates, Toray Spartan(TM) and PEEK film samples, show stable mechanical response over this temperature. Toray Spartan(TM) was found to exhibit good transverse dimensional stability (TDS). Good TDS is an increasingly important attribute of tapes to enable higher track densities. However, Toray Spartan™ suffers from humidity sensitivity and poor creep recovery. PEEK substrates according to various approaches disclosed herein address and solve these problems.

The tensile storage modulus E′ of the PEEK substrates according to various aspects is preferably in the range of about 4 GPa to about 20 GPa, more preferably in the range of about 5 GPa to about 15 GPa, and about 5.5 GPa to about 12 GPa. and preferably near the upper end of this range. The tensile storage modulus E′ can be controlled to some extent by controlling the molecular weight of PEEK, potentially not currently available, but given the teachings presented herein, the potential Ultimately, improvements can be made by the increased crystalline chain orientation of higher molecular weight PEEK materials that will become available once the need for them is established for future tape media.

For the substrate material, a PEEK material having a chemical structure of aromatic polyaryletherketone and a chain length n of at least n=20 is preferred in various approaches. Preferably, the chain length is n=40 or more, such as n=50 to 100. The chain length should not be so long that the PEEK becomes unworkable or brittle.

A variety of aromatic polyaryletherketones can be used in a variety of ways within the scope of this invention. Some exemplary PEEK materials are described below. The description is provided by way of example only and is not intended to be limiting in order to illustrate some of the various types of PEEK that can be used in many aspects of the present invention. .

Please refer to FIG. 6 again. Substrate 604 may be the thickest layer in the magnetic recording tape. The use of PEEK allows for thinner substrates than conventional substrates currently in use, thereby allowing more tape to be wound in conventional tape cartridges. In some approaches, the substrate has a thickness of about 2.5 microns or greater, such as a thickness in the range of about 3 microns to about 8 microns, preferably about 3 microns, measured in a direction perpendicular to the plane of the tape. It has a thickness in the range of microns to about 4.5 microns, although substrates can be thicker or slightly thinner than the upper and lower limits of these ranges.

Exemplary PEEK Materials FIG. 9 illustrates an exemplary PEEK 900 according to various approaches described herein. Optionally, this PEEK 900 can be implemented with features of other approaches described herein, such as features described with respect to other figures. However, it should be appreciated that such PEEK900 and other PEEKs presented herein may or may not be explicitly mentioned in the exemplary approaches described herein. It can be used in various applications or permutations or combinations thereof. Moreover, the PEEK900 presented herein can be used in any desired environment. The various permutations of PEEK 900 disclosed herein enhance the stability and performance of tape storage media throughout the environment in which it is used and stored.

FIG. 10 illustrates another exemplary PEEK 1000 according to various techniques described herein. Optionally, this PEEK 1000 may be implemented with features of other approaches described herein, such as features described with respect to other figures. However, it should be appreciated that such PEEK 1000 and other PEEKs presented herein may or may not be explicitly mentioned in the exemplary approaches described herein. It can be used in various applications or permutations or combinations thereof. Moreover, the PEEK 1000 presented herein can be used in any desired environment. The various permutations of PEEK 1000 disclosed herein improve the stability and performance of tape storage media throughout the environment in which they are used and stored.

Known manufacturing techniques can be used to produce PEEK raw materials that can be used to form substrates. Some approaches use a step growth condensation polymerization reaction.

FIG. 11 illustrates another exemplary PEEK 1100 according to various techniques described herein. Optionally, this PEEK 1100 may be implemented with features of other approaches described herein, such as features described with respect to other figures. However, it should be appreciated that such PEEK 1100 and other PEEKs presented herein may or may not be explicitly mentioned in the exemplary approaches described herein. It can be used in various applications or permutations or combinations thereof. Moreover, the PEEK 1100 presented herein can be used in any desired environment. The various permutations of the PEEK 1100 disclosed herein improve the stability and performance of tape storage media throughout the environment in which they are used and stored.

FIG. 12 shows another exemplary PEEK1200 and its exemplary formation pathways according to various approaches described herein. Optionally, this PEEK 1200 may be implemented with features of other approaches described herein, such as features described with respect to other figures. However, it should be appreciated that such PEEK 1200 and other PEEKs presented herein may or may not be explicitly mentioned in the exemplary approaches described herein. It can be used in various applications or permutations or combinations thereof. Moreover, the PEEK1200 presented herein can be used in any desired environment. The various permutations of the PEEK 1200 disclosed herein improve the stability and performance of tape storage media throughout the environment in which they are used and stored.

As noted above, PEEK 1200 can be manufactured using a step-growth condensation polymerization reaction. An exemplary step-growth condensation polymerization reaction process illustrated in FIG. 12 involves reacting a diphenyl ether such as diphenyl oxide with terephthaloyl chloride (TPC) in the presence of a metal chloride such as AlCl ₃ or FeCl ₃ , HCL is liberated as a by-product. The reaction is usually carried out in a hot melt or aromatic hydrocarbon solvent, so HCl is released as a gas, leading the reaction to very efficient chain growth.

The end groups of PEEK1200 can be groups similar to those shown in FIG. 9 or other figures.

In some approaches, the PEEK raw material can be purchased commercially from a PEEK raw material manufacturer or supplier. In a preferred approach, manufacturers can produce suitable PEEK materials with desired properties, such as chain length, at the request of magnetic recording tape manufacturers following the guidelines set forth herein. . PEEK is typically sold in the form of pellets, which can be processed as described below to form substrates for magnetic recording tapes. In other approaches, a PEEK base sheet can be manufactured or purchased, or both manufactured and purchased, for use in the tape manufacturing process.

KETASPIRE® PEEK material is available from Solvay (Solvay Specialty Polymers USA, LLC, 4500 McGinnis Ferry Road, Alpharetta. GA30005-3914 USA).

PEEK material is also available from Victrex (Victrex USA, Inc., 300 Conshohocken State Road Suite 120, West Conshohocken, PA, 19428 USA).

Currently produced PEEK films are not well suited for use as tape substrates. However, by using the teachings presented herein, those skilled in the art will be able to produce suitable PEEK films with suitable thickness, molecular weight, extrudability and molecular orientation for use as tape substrates. can be done.

PEEK is particularly advantageous for tape applications because it has a very low hygroscopic coefficient of expansion and is insoluble in organic solvents. Therefore, PEEK substrates are less susceptible to water-induced dimensional changes. However, PEEK can be melted and formed into a film. PEEK does not degrade during manufacturing, such as at the high temperatures used in melt extrusion. In contrast, the aramids used in conventional tape products are modified to be soluble. This is because aramid degrades during melting and cannot be melt extruded into films. In order to make aramid soluble in very hot polar organic solvents, the aramid chain must be modified to enhance solubility. The result is increased water absorption and reduced overall dimensional stability at normal use and storage temperatures of the tape media.

To form the substrate, according to one approach, a PEEK raw material is melt extruded and oriented to align the crystalline regions of the resulting substrate such that the crystalline regions are generally aligned with each other. . The melt extrusion process involves heating the PEEK raw material to a temperature at which the melt extruder can extrude the PEEK raw material to form a film of desired thickness. The melt extrusion apparatus and melt extrusion process can be of known design for PEEK materials used in other industries and generally have a die (e.g., nozzle, roller, etc.) through which the PEEK is extruded. and a mechanism for pulling the extruded PEEK. Exemplary substrate manufacturing lines may use melt extrusion and a process called tenting, which achieves highly controlled MD and TD orientation or tensilization. To do so, grippers on rail and chain frames are used that grab the ends of the extruded sheet and pull the sheet laterally and longitudinally in a heated furnace.

As those skilled in the art with this description will appreciate, the temperature used during melt extrusion should be below the degradation temperature of the PEEK raw material. The degradation temperature of PEEK raw materials varies from material to material and is usually much higher than the melting temperature determined by conventional thermal analysis techniques such as differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA). Generally, PEEK polymers are very stable up to temperatures well above their softening point or true melting point. Depending on the molecular structure and chain length of the PEEK polymer, softening occurs at temperatures well above 150°C. Although degradation in air can occur for some PEEK polymers when heated to temperatures above 300°C, 300°C is practical in forming films suitable for magnetic tape substrates. It is believed that the temperature is considerably higher than the effective processing temperature used. Generally, the processing temperature used in the film manufacturing process requires a certain amount of polymer feed to the initial extrusion die head to allow good flow and orientation of the initial sheet as it is picked up by the gripper. Optimized for close to characteristics. The grippers then simultaneously pull the final cooled films in the cross and machine directions of the web to achieve the desired orientation or tensioning of the films.

Conventional conditions for aligning crystalline regions of conventional substrate films can also be used with PEEK in a manner that will be understood by those of ordinary skill in the art upon knowledge of this disclosure. For example, when molten PEEK is drawn during melt extrusion, the molecular chains tend to align with the direction of flow and toward the minimum free volume. Orientation of the film that aligns the crystalline regions allows the production of films with higher modulus and near-perfect elastic creep recovery without sensitivity to water, which is required by current tension compensation schemes. It is expected to provide control of the TDS that

The resulting PEEK sheet can be stored for further processing at a later time, or additional layers can be added to the PEEK sheet. In one aspect, the PEEK sheet is wound onto a spool. In another aspect, one or more additional layers are added to the PEEK sheet.

The PEEK sheet with or without the additional layers can be cut to the width required for subsequent processing, or to the specifications of the final product, or both. For example, a wide PEEK sheet can be cut into strips of widths suitable for use with conventional coating equipment to add additional layers to the sheet.

Underlayer Any underlayer 606 known in the art can be used with the PEEK substrate 604, according to various approaches. Underlayer 606 can be made of known materials and is preferably made of materials that can be grafted to substrate 604 by radiation-induced grafting.

Recording Layer Any recording layer 60 known in the art can be used with the PEEK substrate 604, according to various approaches.

Exemplary Tape Manufacturing Techniques As discussed in more detail below, to manufacture a magnetic recording tape, the PEEK substrate is bonded with one or more additional layers, such as an underlayer and/or a backcoat.

Current magnetic recording tape manufacturing techniques rely on solvent interactions to adhere the layers together or require surface treatments such as plasma cleaning prior to coating. A significant drawback of this surface modification is the susceptibility of the modified substrate to water-induced dimensional changes.

As currently used in tape substrates, one or more additional A layer of can also be added to the PEEK film. Modification of PEEK films to improve adhesion of coatings, which will likely be used to make future magnetic recording tape products, will require one surface to another, as is currently practiced with existing tape substrates. It may be necessary to modify the PEEK film surface by coextrusion of the film material, or by oxidizing one surface using plasma treatment. For radiation cured coatings, especially for the very thin coatings expected in future tape designs, UV Sufficient activation of locations on the PEEK film can be achieved using light. Modification of the monomers used to construct PEEK specifically optimized for use as a substrate for magnetic media completely solves any adhesion problems and applies to magnetic tape media To further improve the performance of the film, functional groups can be introduced into the PEEK film that are activated upon exposure to UV light and that are capable of reacting with the functional groups of the coating.

In a preferred approach, one or more additional layers, such as underlayers or backcoats or both, are attached to the PEEK substrate by radiation-induced grafting of these layers onto the substrate, e.g., light-induced curing (e.g., cross-linking). combined. For example, the underlayer can be extruded next to the PEEK substrate, laminated onto the PEEK substrate, and grafted to the PEEK substrate in real time by exposing to ultraviolet (UV) light and/or other radiation. . Aromatic compounds in PEEK tend to be photoactive and thus lend themselves to the desired radiation-induced curing. Additionally, as will be appreciated by those of ordinary skill in the art upon reading this description, the PEEK source material and/or the adjacent layers can be fabricated to have desired chemical structures to enable radiation-induced grafting. . In some approaches there is no adhesive between the underlayer and the substrate.

In addition, the degree of hardening does not need to be high. A few chemical bonds per 100 monomer units are sufficient for good adhesion because the chemical bonds are much stronger than the weak bonding techniques used in conventional tape media. Chemical bonding of the preferred embodiment is also advantageous with respect to robustness and resistance to stress, since chemical bonds must be broken to separate the layers.

In general, UV light does not penetrate through plastics greater than 1 micron thick. However, the underlayer used in the preferred approach is less than 1 micron thick, thus allowing UV curing to occur.

Various advantages of magnetic recording tapes with novel PEEK substrates over current magnetic recording tape media include, but are not limited to, higher dimensional stability, greater tear resistance, aging (creep) effects. including one or more of such as greater resistance to

It will be apparent from the above description that various features of the above systems and/or methods can be combined in various ways to produce multiple combinations.

It is also understood that the techniques of the present invention can be provided in the form of services that are deployed for customers.

The inventive concept disclosed herein is presented by way of example to illustrate its myriad features as a plurality of exemplary scenarios, embodiments or implementations or combinations thereof. It is to be understood that those concepts generally disclosed are to be considered modular and can be implemented in any combination, permutation or composition thereof. In addition, any alterations, modifications or equivalents of the features, functions and concepts disclosed herein that would be understood by a person of ordinary skill in the art upon reading the description of this specification are also included within the scope of the disclosure. should be considered to be

The descriptions of various embodiments of the invention have been presented for purposes of illustration, and are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art that do not depart from the scope of the described embodiments. The terms used herein are those that best describe the principles of the embodiments, their practical application, or technical improvements not found in the marketed technology or disclosed herein. These embodiments were chosen so that others skilled in the art could understand them.

Claims (39)

A magnetic recording tape,
a substrate comprising polyetheretherketone (PEEK);
a lower layer over the substrate;
and a recording layer overlying said underlayer. 2. The magnetic recording tape of claim 1, wherein the PEEK chain length is greater than about twenty. 2. The magnetic recording tape of claim 1, wherein the PEEK has a chain length of about 50 to about 100. 4. The magnetic recording tape of any of claims 1-3, wherein the substrate has a tensile storage modulus in the range of about 4 GPa to about 20 GPa as measured by dynamic thermomechanical analysis. 5. The magnetic recording tape of any of claims 1-4, wherein the substrate has a tensile storage modulus in the range of about 5.5 GPa to about 12 GPa as determined by dynamic thermomechanical analysis. 6. The magnetic recording tape of any of claims 1-5, wherein the crystalline regions of the substrate are generally aligned with each other. 7. The magnetic recording tape of any of claims 1-6, wherein the thickness of the substrate ranges from about 2.5 microns to about 8 microns. 8. The magnetic recording tape of any of claims 1-7, wherein the thickness of the substrate ranges from about 3 microns to about 4.5 microns. 9. The magnetic recording tape of any of claims 1-8, wherein the underlayer is grafted to the substrate. 10. The magnetic recording tape of any of claims 1-9, wherein no adhesive is present between the underlayer and the substrate. a tape cartridge,
a housing;
a magnetic recording tape at least partially contained within the housing, the magnetic recording tape comprising:
a substrate comprising polyetheretherketone (PEEK);
a lower layer over the substrate;
and a recording layer above said underlayer. 12. The tape cartridge of claim 11, comprising non-volatile memory coupled to said housing. 13. The tape cartridge of claim 11 or 12, wherein the PEEK chain length is greater than about twenty. 13. The tape cartridge of claim 11 or 12, wherein the PEEK has a chain length of about 50 to about 100. 15. The tape cartridge of any of claims 11-14, wherein the substrate has a tensile storage modulus in the range of about 4 GPa to about 20 GPa as measured by dynamic thermomechanical analysis. 15. The tape cartridge of any of claims 11-14, wherein the substrate has a tensile storage modulus in the range of about 5.5 GPa to about 12 GPa as measured by dynamic thermomechanical analysis. 17. The tape cartridge of any of claims 11-16, wherein the crystalline regions of the substrate are generally aligned with each other. 18. The tape cartridge of any of claims 11-17, wherein the substrate has a thickness in the range of about 2.5 microns to about 8 microns. 18. The tape cartridge of any of claims 11-17, wherein the substrate has a thickness in the range of about 3 microns to about 4.5 microns. 20. The tape cartridge of any of claims 11-19, wherein the underlayer is grafted to the substrate. 21. A tape cartridge according to any of claims 11-20, wherein no adhesive is present between said underlayer and said substrate. A method for manufacturing a magnetic recording tape, said method comprising bonding an underlayer to a substrate, said substrate comprising polyetheretherketone (PEEK). 23. The method of claim 22, wherein the PEEK chain length is greater than about 20. 24. The method of claim 22 or 23, wherein the PEEK has a chain length of about 50 to about 100. 25. The method of any of claims 22-24, wherein the substrate has a tensile storage modulus as measured by dynamic thermomechanical analysis in the range of about 4 GPa to about 20 GPa. 25. The method of any of claims 22-24, wherein the substrate has a tensile storage modulus as measured by dynamic thermomechanical analysis in the range of about 5.5 GPa to about 12 GPa. 27. The method of any of claims 22-26, wherein the crystalline regions of the substrate are generally aligned with each other. 28. The method of any of claims 22-27, wherein the thickness of the substrate ranges from about 2.5 microns to about 8 microns. 28. The method of any of claims 22-27, wherein the thickness of the substrate ranges from about 3 microns to about 4.5 microns. 30. The method of any of claims 22-29, wherein bonding the underlayer to the substrate comprises performing radiation-induced grafting. 31. The method of any of claims 22-30, wherein no adhesive is present between the underlayer and the substrate. A method for manufacturing a magnetic recording tape, said method comprising bonding an underlayer to a substrate comprising polyetheretherketone (PEEK) by radiation-induced grafting, and bonding a recording layer to said underlayer. A method, comprising: 33. The method of claim 32, wherein the PEEK chain length is greater than about 20. 33. The method of claim 32, wherein the PEEK has a chain length of about 50 to about 100. 35. The method of any of claims 32-34, wherein the substrate has a tensile storage modulus as measured by dynamic thermomechanical analysis in the range of about 4 GPa to about 20 GPa. 35. The method of any of claims 32-34, wherein the substrate has a tensile storage modulus as measured by dynamic thermomechanical analysis in the range of about 5.5 GPa to about 12 GPa. 37. The method of any of claims 32-36, wherein the crystalline regions of the substrate are generally aligned with each other. 38. The method of any of claims 32-37, wherein the thickness of the substrate ranges from about 2.5 microns to about 8 microns. 39. The method of any of claims 32-38, wherein no adhesive is present between the underlayer and the substrate.

Images