JPS58169587A - Graphite fiber tensile member and production of cable assembly using same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to tensile members and, more particularly, to tensile members constructed primarily of high strength fibers and cables that are subjected to significant and frequent bending.

The exceptional strength properties of fibers of materials such as glass, graphite, Kepler and boron are well known. Such fibers are relatively short (
Chopping 72) The randomly oriented embedding of fibers into rigid matrix (such as epoxy resin) ICs is often used in composite structures made of k.

Such fibers can also be used in virtually unlimited lengths to take advantage of their unique tensile strength V properties. Applications of continuous length fibers are increasing, but most applications appear to be static in nature? It seems like C. That is, the matrix material in which the fibers are embedded is usually rigid, and even in somewhat "flexible" applications such as electrical and optical communications cables or one of the above, the structure is substantially stiff after installation. It appears to be in a stationary state. For such applications, it is feasible to severely limit the bending and stretching forces applied to the structure during transportation and installation.

Many structures require high tensile properties for non-static applications and have relatively very high tensile and flexural strength requirements. Such applications include purely structural cables, as well as rugged cables for transmitting information in non-static environments, such as oil well logging cables and geophysical survey cables.

A typical oil well logging cable has an outer pass surrounding seven or more conductors and having a diameter of less than -34 inches. Every time an oil well is logged, a cable is extended more than 1,000 feet underground.
Thrust valve pressure 2 and coj″G exceeding 2!000981
Or Sakui 1 & over 70! exposed to high temperatures, attacked by highly corrosive chemicals in the spigot, and
．． Accepts tension up to 000 bond. While undergoing these stresses, the cable passes around a pulley having a radius of, for example, t-11x feet to 3 feet. Heretofore, typical prior art tensile members utilizing high strength fibers have not been suitable for use in the necessary conditions found in oil well logging.

The primary object of the present invention is to provide an improved method for making tensile assemblies from tows of high strength filaments and to provide tensile assemblies made of these filaments.

To achieve this and other objectives, in accordance with one aspect of the present invention. That is, in a method of making a medium length elongate tensile assembly, a medium length high strength screw saturated with a semi-cured polymeric impregnant is used.2. The promoted inclusions are sufficient to promote keying of multiple tows of the ment and to prevent saturated tows from substantially merging with each other or with other #families with which the tows may come into contact. curing the impregnating agent and spirally forming the plurality of impregnated tows around each other, and subsequently drying or substantially drying the impregnating agent in the spirally formed saturated tows while in the spiral arrangement. It hardens to form a solid matrix while remaining in a non-tacky state, allowing the tows to act in unison when the assembly is subjected to tension and preventing the tows from bonding together. K to give the assembly considerable strippability.

Another aspect of the invention is that the tows of separate helically formed filaments, which are not bonded, extend helically around each other along the length of the assembly and do not connect the tows to each other. the tow is saturated with a solid polymeric impregnant to bond the filaments of each said tow in a substantially rigid helical matrix; .

Another aspect of the present invention is to saturate a tow of graphite filaments of unlimited length with an uncured polymeric impregnant to fill the voids and interstices of said filaments, and remove excess impregnation from the saturated tow. removing the impregnated tow with a release agent to minimize bonding of the tow with other materials, and curing the impregnating agent while forming the impregnated tow into a helix. This is achieved by a method of making an elongated tensile member of intermediate length comprising the steps of: maintaining the helically formed saturated tow in a solid matrix; .

The present invention will be explained below with reference to the accompanying drawings.

FIG. 1A shows a section of a high strength graphite filament tow, which is a substantially untwisted or twisted yarn of multiple fibers extending longitudinally in contact with each other. Most fibers extend the entire length of the tow, and the tow has an indeterminate length. Since the fibers are not of precisely uniform length, some types of fibers (or filaments) are exposed to greater stresses than other fibers when the tow is under tension.

Figure 1B schematically illustrates this principle.
The filaments t, t have relatively long lengths and are exposed to little or no tensile stress.

When a tow of such filaments is subjected to tension, the full rxM theoretical tensile strength of the tow (the tensile strength of a single filament multiplied by the number of filaments) is not achieved.

This is because relatively short filaments are exposed to stresses that exceed their tensile strength and break, and the load is then transferred to the next relatively long filament. Thus,
The tow is very flexible and can be bent over a short radius when not subjected to large tensions, and has severely limited tensile strength.

Impregnating the tow with a rigid or semi-rigid (after curing) matrix increases the tensile strength of the tow over that of the unimpregnated tow by distributing the load to the individual filaments. This limits the lateral mobility of the fibers, so that comparatively long fibers “straighten” when subjected to tension, thereby distributing their share of the tensile load.
Therefore, the greater the stiffness of the matrix used, the greater the tensile strength of the tow, but the lower the flammability.

FIG. 4 schematically depicts an apparatus for saturating a continuous tow of high strength filaments with a liquid polymer soaking agent.

A continuous tow 12 of high strength filament is fed under tension from a reel 1 and passed through an orifice /6 of a vacuum chamber 11. The orifice/6 is able to hold the tow/6 without significant friction that would break the individual filaments.
, 2 can pass through. A vacuum pump J connected to the chamber 15 via an oil bath n maintains a near vacuum in the chamber Is. The oil bath n protects the bonder against broken fibers that come loose from the tow 12.

The tow 12 then passes through an orifice J into a bath of liquid polymer impregnant. Bath water is replenished from hopper U. The tow is above the spreader 30 and the spreader 32
It is desirable to completely wet the filament with bath water by passing under the bath water. The spreader may be, for example, a rod fixed transversely to the path of the tow/U, thereby spreading the tow laterally.

Tow l- exits the bath via orifice 3II. This orifice 3'l is dimensioned so that the tow can pass through it without friction that would damage the individual filaments. However, orifice 3II is preferably small enough to remove excess saturant from the saturated tow. A sponge or cloth wiper 31 may also be used to remove excess saturant from the saturated tow.

FIG. 3 shows a generally circular cross-section of tow saturated with impregnating agent. Each filament is thoroughly saturated throughout its length, with no air bubbles or color gaps.

□ In one embodiment, the tow saturated with uncured liquid impregnation agent is coated with a suitable release agent. This prevents the tow from bonding to other tows or other materials in the composite structure in which it is used when the saturant is cured. The figure below shows the process of wrapping the tow with a suitable film band, such as a polyester tube. The taping process is preferably carried out immediately following removal of excess impregnating agent and prior to winding of the saturated tow. Alternatively, the tow is extruded onto the surface of the saturated tow or It can be coated with a release agent such as a soft wax that is rubbed (ie, canaraba wax) or a suitable polymeric (thermoplastic or thermoset) material that is extruded onto the saturated tow. The extrusion process is carried out by applying as little heat as possible to prevent curing of the impregnating agent and unduly shortening the pot life of the expanding impregnating agent.

After coating the saturated tow, it is stored on a reel or bobbin *1 and, if necessary, at low temperature to prevent hardening of the impregnating agent.

coated. Wrap the saturated tow onto each bobbin and place the bobbins into their respective arbor of the cabling machine. The tow is then spirally laid over the central core in one or more layers, and the impregnant is cured at room temperature or with the application of heat.

Some of the impregnating agent escapes the release agent surrounding the tow, thereby partially bonding to the adjacent tow K (or to other members of the composite cable assembly). However, while the cable is easy to bend.

1 operation, i.e., normal use, breaks such bonds and increases flexibility. As with conventional cables,
Bending the cable assembly allows the strength members to move longitudinally relative to each other.

Cabling (or helical laying) of the tensile members increases the flexibility of the cable assembly.

@! The figure shows the application of the above technique to produce a coaxial cable assembly that can be used for oil field drilling logging. The cable assembly has a central single conductor V that is twisted into a strand.

1. The conductor 60 is surrounded by an extruded thermoplastic coating 12. A coaxial sheathing of the wire cup is laid over the sheathing 1.2, and this coaxial sheathing is then covered with an extruded thermoplastic sheathing 66.

1 coaxial 1 assembly ω to 66 is used as the central core,
Through this central core, the cabling machine.

Two layers of impregnated and coated high strength filament tow 4
Lay it in a spiral at 1.70. Layer 70 can be wrapped in a polymeric film (not shown) and then coated with thermoplastic material 7.

As shown in Fig. 3, in the actually produced cable assembly, the core has an outer diameter of 0.3 finch, and each tow is per tow/! Union Carbide Grade WYP6-I10 with ,000 filaments
Consists of graphite filaments. This graphite filament is made of graphitized polyacrylonitrile (
PAN) and has the necessary tensile strength, long elongation at break, and flexibility for that purpose. The impregnating agent used was a fluid polymer system (Flu
d(”'+ 1゜Polynnr 8yst@ms), P, 0
．． Box Ta λt, II Cajan.

OA? XGL7-449 available from Ko022
N again. The pot life of the XGL7-μ9'E was long enough to impregnate the tow, and the tape was wrapped as shown in Figure 4' and wound onto the bobbin of a conventional freeway cabling machine.

XGL7-Hiroshi91 has about 1 to VmII when cured.
! (3.70 M pal) <7) FIiJ &
'j' coefficient, about t/,s! /an”(/4.0
M pal ) bending strength of approximately 4. /Kp/Ill
” tensile strength of (jkl/ρpa1) and approximately tλD
It has an image quality of "D" hardness. Dry yarn experimentally 61
The average tensile strength determined for 1j was about 30,000 pml, and the average tensile strength of 1'-ton (cured) impregnated with XGL7-9E epoxy was about 330,000 pml. It has a rated tensile strength of 40,000p. GIP8 (Fake 1vanlzcdImproved
Plow 5teel) is superior to materials commonly used in logging cable strength members.

Following the winding of the saturated tow onto the bobbin, the cabling machine bobbin (and bobbin arbor) was cooled. The tow was laid in a reverse helix over a central core 1 km long. The assembly was then immediately taped with polymer film and stored at /10"F for two days to cure the impregnant. After saponification, the assembly was "used" to increase its flexibility. After that, Tefz@l
A 30 mil thick jacket was extruded over the assembly to complete the cable. Note that if an impregnating agent with a pot life shorter than that of XGL749F is used, it may be necessary to perform some or all process steps at lower than rotten temperatures.

In other embodiments of the invention, the first and second
A tow is obtained that does not require the release agent of the example. The graphite fiber used in this example is Thorn@l JOO (UnionCark+
1d) available on the market. The impregnating agent may be, for example, an epoxy novolak with a hardening tip. A suitable epoxy is Fib@rlts 2urB (Fib@rit*
Mmu faeturlng Company, W
Inona, Minn, ).

The tow can be saturated with an impregnating agent as part of a continuous process, or the tow can be purchased on the market in a semi-cured, B-stage state ready for further processing. can. Such semi-cured tow, for example HY
E lo<<r B C (Fib@r口・Manufa
aturlng Company), which is then processed or woven into a more complex material or fabric, and then cured into a solid component.

This is because the tow crosslinks with each other during final curing.

As shown in the figure, the semi-cured tow/10 is attached to the pay-out bobbin //J of the cabling machine llj. The tow and bobbin may have been previously cooled to prevent further hardening of the impregnating agent. The individual tows/10 are then unwound and passed through a heating tunnel/20 heated by a heating device 1, which accelerates the hardening of the impregnated tows.

When a kB single-stage impregnation agent is heated to accelerate curing, its surface usually becomes smeared again, i.e., “viscosity > +7
This makes it easier for the tows to bond again to each other or to other materials with which they may come into contact.
In the present invention, by providing sufficient dwell time to cure the accelerated impregnating agent, the viewing surface becomes dry, i.e., non-tacky, again, and even when heated, the saturated tow can or prevent the tow from substantially bonding to other materials with which it may come into contact. Heating tunnel/10
the length of the tow 110, the speed of movement of the tow 110, and the heating tunnel/
All temperatures within the pot are adjusted to provide the desired degree of acceleration and hardening of the impregnated tow.

Next 1) A series of molding dies 12! to guide or guide through. These dies form each tow into a ring shape, such as the non-circular cross-section shown in the figure, by lateral rolling. Then 5 toes are closed eyes/
Proceed to X), where the tow is helically wound or shaped around each other. In a preferred embodiment, a cable is created. The tow III is thus wrapped around a cable" core/32, such as the type used in coaxial communication cables.

As the cross-sectional view of the cable shown in Figure 6 shows, the individual tows at this point are even more pressed into the shape of a non-circular cross-section so that the tows have little or no gap between them. occupies the smallest cross-sectional area without. This is, of course, very philistine. This is because it keeps the total cable volume as small as possible and increases cable strength and stability. Furthermore, the above-mentioned hardening process makes it possible to perform the filling operation of the high-density box without causing the impregnating agents in the tow to bind or coalesce together.

It is then desirable to run the assembly through the circumference of several post-forming pulleys (not shown) that bend the assembly, as still a small amount of bonding may occur from time to time. This results in the breaking of a small number of bonds, such as those formed between adjacent tows, during the curing of the saturated tows following the helical laying of the tows.

If, on the other hand, a cable assembly is to be provided with a larger number of co-rotating tows//10, the assembly 100 coming out of the cabling machine//j is fed to another cabling machine. Then essentially the same process is carried out again to add the second layer of tow/10. That is,
Assembly 1 is then processed in the same manner as it was processed by the operations described above in machine //j. Figure io shows a cross-section of the resulting cable strength.

Then one kind of jacket ends up as a cable assembly/+0
If it is necessary to provide Tefz
@l ) (a Dupont fluorocar
Tape, such as bon) tape, may be wrapped around the cable assembly for reasons discussed elsewhere below.

*Accumulate the aUC, cable assembly/uO on a conventional take-up reel (not shown). Then additional post-
The cable assembly can be placed in a heat box (not shown) for curing to further realize the potential of the assembly.

An outer jacket, such as a Tefzel jacket, can then be pushed over the cable assembly by conventional means. Cable assembly due to heat during extrusion process/
It was found that a small amount of gas was instantaneously generated from 110 organic compounds. This tape wrapping operation advantageously includes the generation of such gas to prevent the formation of air bubbles in the jacket before it has had a chance to cool and solidify. As can be appreciated, the present invention has a number of advantages. Primarily, the present invention is versatile, inexpensive, and reliable for making elongated tensile assemblies of substantial intermediate length. An effective method and resulting assembly is provided. The assembly includes a plurality of tows of impregnated strength members that are free of residual stresses in a shaped and fully cured helical arrangement of tows in one strength member. Depending on the method of the present invention being practiced with known materials, the tows remain unique and slide freely over each other to readily accommodate bending of the strength member assembly.

Although the methods and products described herein constitute preferred embodiments of the invention, it is understood that the invention is not limited to these precise products and methods, and that the invention is not limited to these precise products and methods. It is to be understood that changes may be made without departing from the scope of the invention.

[Brief explanation of the drawing]

The first diagram shows the tow part of the high-strength filament! Figure 8, Figure KK shows the three filament sections of the tow under tension, and Figure 2 is a schematic cross-sectional view of an apparatus for saturating a continuous length of tow of high-strength filaments with a liquid impregnating agent. , FIG. 3 is a schematic cross-sectional view of a filament tow saturated with impregnating agent, FIG. FIG. 6 is a longitudinal side view of an apparatus for making a tensile strength member according to the present invention; FIG. Figure 1 is a cross-sectional view taken along line 2 in Figure 1. Figure 1 is a cross-sectional view taken along @3-J in Figure 1 of the tow shaped just before the cabling. FIG. 7 is a cross-sectional view of the cable made according to the present invention taken along the line of FIG. FIG. 10 is a cross-sectional view of another cable made in accordance with the present invention. L mail 1 concave pa 9 engraving inside 8 and 1! W na L no FIG, iA FIG, iB anger FIG, 3 FIG, 4FIG,
5 6 FIG, 7 Procedural amendment (method) 1. Display of the case Showa Kugi Year Patent Application No. 216762 2, Title of the invention 3, Person making the amendment Relationship to the case Patent applicant Sieran A=l-, O A-Sieme, Nis, Nie Figure II
and a document certifying the relationship between the head office and the business office.Contents of color correction.S+M engraving as shown in the attached sheet (no alterations to the contents) 602-

Claims (1)

Claims: / In an elongated tensile strength assembly of intermediate length, a plurality of unbonded, helically formed, separate filament tows are helically interleaved with each other along the length of the assembly. and that the tows are saturated with a solid polymeric impregnating agent to bond the filaments of each said tow in a rigid helical matrix while leaving the tows unbonded with each other. Features tensile strength assembly. - Claim 7, wherein the impregnating agent consists of an epoxy phase-resistant material.
Tensile assembly as described in Section 1. 3. The tensile strength assembly according to Section 1 or Section 1, in which the impregnating agent is hydrolytically stable, in the range of % d*-. A tensile strength assembly e j according to claim 1 , wherein each tow comprises a continuous length of carbon filaments between about J,000 and about JO,0000, wherein the release agent is A tensile strength assembly according to any one of claims 1 to 3, which is utilized to prevent tows from bonding together. 6. A tensile strength assembly according to any one of claims 1 to 5, wherein the tow is helically formed. 7. A tensile strength assembly as claimed in claim 1, wherein the threaded connection is formed around the central core. 8. The tensile strength assembly of claim 7, wherein the central core comprises a composite structure having at least one electrical conductor. ? , a central core portion of which is at least one optical fiber 4-
8. A tensile strength assembly according to claim 7, comprising a composite structure having: 10. Jacket means is provided surrounding the front 1iC member to protect the tensile strength member against wear and lateral shear stress when the assembly is in use. or the tensile strength assembly described in paragraph 1. ii. In a method of making a medium length elongate tensile assembly, promoting the kiering of 4jL number of tows of medium length tensile filaments saturated with a semi-cured polymeric impregnant so that the saturated tows may contact. To prevent substantial bonding to other materials, the accelerated impregnating agent is sufficiently cured, multiple impregnated tows are helically formed around each other, and then the helically formed The impregnating agent in the saturated tow is cured to a solid matrix while in the helical configuration and while remaining substantially dry or non-tacky, so that the assembly is under tension. 4. A method that allows the tows to act in unison when received, and also provides considerable dainty to the assembly by the fact that the tows do not bond to each other. /-1 The method of paragraph 1/-1, wherein each accelerated tow is formed into a non-circular cross-section prior to being formed into a spiral. /j, The step of forming the impregnated tow in a helical shape with respect to each other further includes forming the tow into a partially cylindrical cable core member such that the tow does not bond to the cable core member in a partially cured state. 13. A method according to claim 1 or 12, comprising laying the tow in a helical manner. 14. A method as claimed in claim 1, in which the reverse helically formed assembly is post-cured to further characterize its potential strength. ij, the assembly after substantial curing of the impregnant in order to break up a few impregnant bonds such as those formed between adjacent tows during curing of the saturated tow following helical laying. 74'. A method according to any one of claims 1/74', comprising the step of bending. 11. The step of helically disposing the tow around the central core comprises disposing at least two layers of impregnated tow around the central core in a reverse helical manner. /
12. The method according to any one of items 1 to 11. /7. Multiple tows of intermediate length cylindrical strength filament,
individually saturated with an uncured polymeric impregnant to fill the voids and interstices between the filaments with the impregnant, and semi-cure the saturated tows so that the saturated tows do not bind to other tows or tows. Any of claims 1 to 76, wherein the saturated tow of step (-) is produced by the step of preventing the tow from substantially bonding to materials with which it may come into contact. The method described in one of the above. /J', a method for making elongated tensile members of indeterminate length, in which a tow of Gra7eye filament of undefined length is saturated with an uncured polymeric impregnant to fill the voids and the filament. filling the gaps between the saturated tow, removing excess impregnating agent from the saturated tow, and coating the previous ml of impregnated tow with release agent to minimize bonding of said tow with other materials; The impregnating agent is maintained in an uncured state while the impregnated tow is formed into a cotton wire, and the impregnating agent in the spirally formed saturated tow is subsequently cured to form a solid matrix. A method characterized by: