JPS6253627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method and apparatus for joining opposing elongate webs of flexible material, and more particularly, for protecting the edges of a heat-sensitive web during subsequent processing in a high temperature environment. The invention relates to a method and apparatus for splicing a web of heat-sensitive material to a second web in a manner contemplated for the invention.

Polyacrylonitrile (PAN) or other carbonized material by first oxidizing the material and then heating the material in an inert atmosphere to a temperature sufficient to substantially carbonize the material. It is known that carbonization occurs. In the case of PAN, the material is often processed in the form of elongated webs of tows, which are arranged in generally parallel rows along the length of the web thereby formed.
The web is fed under tension through a relatively complex path defined by rollers into one or more oxidation furnaces and then introduced into a charring furnace. Within the oxidation furnace the web is passed through a number of different stages of the furnace maintained at a temperature that achieves the desired oxidation of the PAN tow.

Due to the nature of the PAN tow, the web is not allowed to remain in the oxidation furnace and must be continuously moved through the oxidation furnace at oxidation temperatures. If the web remains in the furnace for any length of time,
Rapid deterioration of PAN tow and exothermic reactions can occur. Additionally, the tow must be free of open ends or knots even as the web is continuously moved through the oven. If an open end or node is present,
They usually generate heat in the high temperature furnace, resulting in process interruption, often requiring a complete shutdown and reintroduction of the web into the cold oxidation furnace.

For this reason, webs of PAN tow are typically introduced into the oxidation furnace when cold. To accomplish this introduction, individual tows are tied at various locations along the length of a threader bar with cables attached to each end. Cables are used to pull the threader bar and mounting tow through the oxidation furnace. Because the furnace is cold, the knots and open ends of the tow where they are tied to the threaded bar do not generate heat.

When the tow has been drawn completely through the oxidation furnace by the threader bar, the furnace is turned on and heated to the oxidation temperature, and the web of tow continues to be fed through the furnace. The furnace typically takes approximately two hours to reach oxidation temperature, during which time the web is continuously drawn through the furnace. Once the furnace reaches the oxidation temperature, the new portion of the web that enters and is drawn through the furnace is oxidized in the desired manner. The leading portion of the web, which typically comprises about 200 to 400 pounds of PAN tow, must be discarded as waste. Since PAN tow is relatively expensive, this is quite disadvantageous in terms of overall process economics.

Continuing this type of process indefinitely is almost impractical due to the need to keep personnel on hand 24 hours a day. Additionally, power failures or other disturbances typically result in the need to cool down the oxidation furnace, after which the startup process must be repeated. Also, periodic work stoppages are required due to the limited length of raw tow carried on the supply spool. Therefore, a considerable amount of wear and tear on the PAN tow becomes a regular and necessary part of carrying out such processes.

Because it is necessary to place the web of material under appropriate tension in the oxidation furnace in preparation for the oxidation of new PAN tow, one technique commonly used to stop the process is to stop the furnace. After
The goal is to continue moving the web through the furnace until the furnace has cooled sufficiently so that the web can be put to rest. On the next start-up, movement of the web through the furnace begins and the furnace is heated to the oxidation temperature. Portions of the web that are moved through the furnace during furnace cooling and subsequent furnace start-up must be discarded as waste.

In some cases, individual tows of web are cut at the entrance to the furnace after the furnace has cooled and the passage of web therein has ceased. Once this occurs, the process begins by anchoring the PAN tow in the web oven to be oxidized. In this case, the individual tows of the web to be introduced into the oven are tied to the individual tows of the web in the oven, and then the advance of the web in the oven is started. To prevent heating of the knots and open ends where the tow is tied, the furnace is operated in stages, each stage being activated after the tow knot has passed through that stage. Again, a significant amount of
PAN tow is worn out.

PAN rather than individual tows of PAN material
woven fabrics, the fabrics were joined using techniques such as those shown in US Pat. No. 4,077,822. In this patent, webs of PAN tow are spliced using multiple layers of silicone rubber adhesive. One layer of adhesive is placed between the overlapping portions of the web, and the other layer is applied to the outside of the overlapping portions of the web. Heat and pressure are applied to cure the silicone rubber adhesive layer.

U.S. Patent Application No. 483,922 describes a process in which a web of PAN tow is introduced into an oxidation furnace, first passing a leader in the form of a web of silica cloth or other refractory material through the furnace. feed, then heat the furnace if it is not already heated. The trailing edge of the leader, which remains outside the furnace, is then spliced to the leading edge of the web of carbonized tow, and the leader is then used to pull the web of tow through the furnace. The use of a heat resistant leader greatly reduces wear on the carbonized tow web.

The patent application described above describes a process for splicing the trailing edge of a leader to the leading edge of a web of PAN tow, the two edges being taped together, sewn and folded over to form a loop, and then A long and thin rod is inserted into the hole. The two edges are then secured into a splice bar, the opposing halves of which define a slot for receiving the two edges and an insertion rod. After the leading edge passes through the oxidation furnace, the splice bar is removed to release the leading edge of the carbonized tow web from the leader.

The trailing edge of the leader described in the above patent application
Although the technique of splicing the leading edge of the PAN tow web was shown to be very satisfactory,
Particular situations where elongated webs are to be spliced in a flexible manner and where one side of the web is composed of heat-sensitive material and must therefore be protected against heat generation and other problems in high temperature environments. which can be applied to
It would be desirable to provide alternative methods and apparatus for accomplishing web bonding. The aforementioned US Pat. No. 4,077,822 does not provide guidance in this field.
That is, it deals with the different problems of splicing different webs of carbonized tow and does not take into account the protection of one web when the other web is made of silica cloth or other refractory materials.

It is therefore an object of the present invention to provide a method and apparatus for splicing opposing elongate webs in a flexible manner.

Another object of the present invention is to provide a method and apparatus for obtaining a flexible, heat-protecting splice between a heat-sensitive elongate web and another web.

The method and apparatus of the present invention provide for flexible splicing of opposing elongate webs.
If one of the webs is comprised of a heat-sensitive material, this web is bonded to the second web to protect the heat-sensitive web in high temperature environments. If the heat-sensitive web is constructed from tows of carbonized material, flexible splices cover the exposed ends of the tows at the edges of the web so as to significantly reduce the potential for heat generation of the tows. do.

Bonding of a heat-sensitive web and a heat-resistant web in accordance with the present invention is accomplished by applying an adhesive coating to a portion of the surface of the heat-resistant web to form a first adhesive layer. An edge of the heat-sensitive web is then placed over some but not all of the first adhesive layer. A cover of heat resistant material is then provided;
Its underside is coated with adhesive to provide a second adhesive layer. The cover is then placed over the edge of the heat-sensitive web so that the second adhesive layer on the underside of the cover bonds to the side of the heat-sensitive web opposite the heat-resistant web and Bonding to the portion of the first adhesive layer that extends beyond the edge. Heat and pressure are then applied to cure the adhesive layer.

The heat resistant cover is preferably applied so that its dimensions are approximately equal to and coextensive with the first adhesive layer. Also, the web of heat-sensitive material preferably covers approximately 60% of the first adhesive layer and approximately 40% of the first adhesive layer is exposed to the second adhesive layer on the underside of the cover. Ru. The ends of the tow defining the edges of the heat-sensitive web are covered with tape prior to bonding the heat-sensitive web to the first adhesive layer.

The web of heat-sensitive material is constructed from a tow of carbonized material, such as polyacrylonitrile material. The heat resistant web and cover are constructed from silica cloth or other heat resistant material. The adhesive layer preferably consists of a silicone rubber adhesive.

These and other objects, features and advantages of the invention will become apparent from the following more detailed description of preferred embodiments of the invention, illustrated in the accompanying drawings.

FIG. 1 shows an apparatus used in a continuous process to oxidize webs of carbonized tow. The apparatus includes a rack 10 on which a plurality of creels 12 are mounted, each of which is wrapped with a tow of carbonized material. In this embodiment, the tows are made of PAN material, each tow consisting of 3000 to 12000 filaments, the number depending in part on the spacing of the tows in the web formed by the tows. As seen in FIG. 1, individual tows 14 are unwound from the various creels and drawn through an assembly of combs 18 into a foil yarn inserter 16. Tow 14
The comb 18 serves as a guide as the yarn is unwound and drawn from the creel 12 into a relatively flat horizontal web 20 at the input to the foil yarn inserter. The web 20 has a width of up to 53 inches (1346 mm) and is comprised of 600 tows 14.

The foil yarn inserter 16 serves to interlace the foil yarn with the various tows 14 and retain the various tows 14 of the web 20 for subsequent processing. An example of a film yarn inserter 16 is shown in US Pat. No. 4,173,990 to Spain et al. The film yarn inserted by the film yarn inserter 16 is removed after oxidation and subsequent processing of the web 20;
This allows the tows 14 to be wrapped individually or as a group rather than just part of the entire web 20.

After insertion of the foil yarn, the web 20 is fed into a tension stand 22 which is comprised of a plurality of spaced apart rollers 24. Tension stand 22
After passing through alternating paths around various rollers 24, the web 20 exits the tension stand 22 and is fed into a first oxidation furnace 26. Tension stand 22 is of normal design and is
0 ensures proper tension on the web 20 as it enters the oxidation furnace 26.

Oxidation furnace 26 together with second oxidation furnace 28 constitute an oxidation furnace assembly. Within the first oxidation furnace 26, the web 20 passes through a relatively tortuous path and wraps around a variety of different rollers 32 mounted at opposite ends of the furnace 26. Web 20 from first furnace 26
is drawn into the second oxidation furnace 28 where the web again passes through a relatively tortuous path and wraps around a plurality of rollers 34 at opposite ends of the furnace 28. Although not shown in Figure 1, the oxidation furnace 2
6,28 is typically internally divided into a number of different stages, each stage being maintained at a somewhat different temperature than the other stages. Roller 3 of furnace 26, 28
2 and 34 are the tension stand 22 and the furnace 28
maintains the desired tension in the web 20 as it is pulled through the furnaces 26, 28. At least some of the tension results from shrinkage as the PAN material comprising web 20 is oxidized. At the exit of the second oxidation furnace 28, the web 20 is directed through a tension stand 35 onto a rotating take-up roll 36, where it is stored for carbonization and subsequent processing.
Tension stand 35 is similar in structure to tension stand 22.

FIG. 2 shows in particular detail a portion of the apparatus of FIG. 1, including the film yarn inserter 16 and tension stand 22. As shown in FIG. As seen in Figure 2,
Individual tows 14 drawn from creel 12 through comb 18 are drawn between a pair of opposing rollers 38, 40 where web 20 is formed. As described in said U.S. Pat. No. 4,173,990, alternate ones of the tows 14 moving between rollers 38, 40 are separated from the rest by healds 42, 44 which form part of the foil yarn inserter 16. Separated. The rapier assembly 46 inserts the foil yarn 48 between the separating tows 14, after which the separating tows 14 reconverge into a single plane to form the foil yarn 48.
Become one with. As seen in FIG. 2, the foil yarns 48 are staggered back and forth across the width of the web 20 in a zigzag fashion.

FIG. 3 shows successive process steps in the method of introducing web 20 into oxidation furnaces 26,28. First, a leader in the form of an elongated web of refractory material is placed in an oxidation furnace.
6, 28 and then the trailing edge of the leader is joined to the leading edge of the web of tow to be oxidized. The leader is then used to draw the web of tow through furnaces 26, 28, where the web tow is oxidized in the desired manner. Tension stand 3 with the leading edge of the web of the tow adjacent to the outlet end of the second furnace 28
5, the leading edge is separated from the trailing edge of the leader. By using a heat-resistant reader,
Before the web of carbonized tow is introduced into and passed through the furnace, the furnaces 26, 28 can be heated to oxidation temperatures, thereby minimizing or eliminating wastage of the carbonized tow.

As shown by a first process step 52 in FIG. 3, a refractory leader consisting of an elongated web of refractory material, such as silica or aramid cloth, is fed into the oxidation furnaces 26, 28, and the leader is completely or substantially completely so that its trailing edge remains outside and adjacent the inlet 50 of the furnace 26. In the second process step 53,
Oxidation furnaces 26, 28 are heated to oxidation temperatures if they are not already heated. Third process step 54
At , the leading edge of the web 20 formed by the tow 14 and applied by the foil yarn inserter 16 is spliced to the trailing edge of the leader. In a fourth process step 56, feeding of the leader through the furnaces 26, 28 is continued so that the web 20 is transferred to the oxidation furnace 26, 28.
6, 28 and sent through the furnace. When the leading edge of the web 20 of carbonized tow 14 has completely passed through the furnaces 26, 28 and the tension stand 35, it is separated from the trailing edge of the leader in the next fifth process step 58.

According to the method shown in FIG.
6,28. The leader can remain within the furnace 26, 28 without being adversely affected. In a more typical situation, i.e., when the apparatus of FIG. will be sent to At the next start of the process, the furnace is heated to the oxidation temperature while the refractory leader remains within the furnace 26,28. Meanwhile, the trailing edge of the leader is spliced to the leading edge of web 20, and once the oxidation temperature is reached, the leader and web 20 can be advanced through ovens 26,28.

The '483,922 patent describes a method and apparatus for joining a web 20 of carbonized tow to a refractory leader 78, in which opposite edges of the web are covered with a facing tape, and the opposite edges of the web are covered with a facing tape, and The tow portion of the extending web 20 is then cut.
Each of the edges thus formed is then sewn along its length and then folded over to form a loop into which an elongated rod is inserted. The opposing edges and insertion rods are then placed between opposing halves of the elongated splice bar, and the opposing halves are then drawn together by tightening the screws along the length of the bar, thereby drawing the opposing webs into the splice bar. sticks to. When the splice bar has been fully fed through the oxidation furnaces 26, 28, the web 20 is separated from the refractory leader by loosening screws along the length of the splice bar, thereby separating the opposing halves of the bar. to release the previously secured edges of the web.

The present invention provides another method and apparatus for providing a flexible splice of a web 20 to a heat resistant leader, which method and apparatus may be used in other environments where two different elongate webs are to be joined. is also applicable. The successive steps of this method are shown in FIGS.

Referring to FIG. 4, in a first step 64,
A cover 66 of glass cloth, aramid cloth or other heat resistant flexible material is prepared. As seen in FIG. 5, the cover 66 has a width W equal to the width of the elongated web 68 forming the refractory leader. Web 68 is also constructed of glass or aramid cloth or other heat resistant material. The width W of the cover 66 and web 68 is approximately 1/2 inch (12.7 mm), which is greater than the width of the carbonized tow web 20. Cover 66 has a length L, which can be any suitable value, but in this example the length is 10 inches (254 mm).

In a second step 70, shown in FIG. 4, a coating or layer 72 of adhesive is applied to the end of the web 68 adjacent its edge 74. Adhesive coating 72 is approximately equal in size to cover 66.

In a third step 76, shown in FIG.
2, the web 68 and its adhesive layer cover approximately one quarter of each opposing edge of the web 20.
Extend beyond 1 inch (6.4 mm). Prior to this, opposing tape is applied to opposite sides of the end 78 of the web 20 and the portion of the tow that extends beyond the tape is cut away to form the edge 80 of the web 20. The top tape 82 is shown in FIG. 5 and the bottom tape is not visible. An end 78 of the web 20 is placed on the adhesive layer 72 such that the end 78 covers some, but not all, of the adhesive layer 72. In this embodiment, the edge 78 of the web 20 covers approximately 60% of the area of the adhesive layer 72 and the edge 80 extends approximately 6 inches (152 cm) from the edge 74 of the web 68.
mm). This leaves a 4 inch (102 mm) wide strip of adhesive layer 72 exposed.

In the next step 84 shown in FIG. 4, a second adhesive coating or layer 86 is applied to the underside of the cover 66. Layer 86 and first adhesive layer 72
is composed of silicone rubber adhesive, an example of which is GERTV No.31. The coding or layers 72, 86 have a thickness of approximately 1/8 inch (3.2 mm) in this example, but may have any suitable thickness as desired.

In the next step 88 shown in FIG.
6 is placed over the edge 78 of the web 20 and the exposed portion of the adhesive layer 72 so that the cover 66 and adhesive coating 86 are coextensive with the first adhesive coating 72. This causes adhesive coating 86 on the underside of cover 66 to
0 end 78 and the exposed portion of adhesive coating 72. 1/ greater than the width of web 20
Cover 66, having a width W of 2 inches, extends by 1/4 inch beyond each opposing edge of the web.

In the next step 90 shown in FIG. 4, heat and pressure are applied to the webs 20, 68 and cover 66 and adhesive layers 72, 86 to cure the adhesive.
When applying a pressure of 7 to 15 psi at a temperature of 200 to 300 °C (93 to 149 °C), the cure is 5.
It was found to be substantially complete in ~15 minutes. Heating under pressure can be accomplished in an air press using opposing Teflon release sheets placed on opposing hot plates within the press.

The completed splice is shown in FIG.
As shown, end 78 of web 20 is sandwiched between and protected by heat resistant web 68 and heat resistant cover 66. The ends of the individual tows that make up the web 20 at the edge 80 are connected to the cover 66, the web 68 and the intervening adhesive layer 7.
2,86, thereby minimizing or eliminating the potential for exothermic reactions in the high temperature environments of oxidation and similar processes. At the same time, the splice was found to be highly flexible and yet very strong. At the end of oxidation or other treatment, the web 6 adjacent to the splice
8 or by cutting through the splice itself, which consists of the web 68, the cover 66, the adhesive layers 72, 86, and possibly a portion of the end 78 of the web 20.
Web 20 can be separated from web 68.

Although the invention has been particularly illustrated and described with reference to preferred embodiments thereof, those skilled in the art will appreciate that various changes may be made in form and detail without departing from the spirit and scope of the invention. Will.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an apparatus used in the process of oxidizing a web of carbonized tow. Figure 2 is the first
1 is a perspective view of a portion of the film yarn inserter and adjacent tension stand of the illustrated apparatus; FIG. FIG. 3 is a block diagram of successive process steps in a method for introducing a web of carbonized tow into an oxidation furnace within the apparatus of FIG. FIG. 4 is a block diagram of successive process steps in a method of providing a flexible splice in accordance with the present invention. 5 is a perspective view of opposing webs and a cover useful in the method of FIG. 4; FIG. FIG. 6 is an end view of the opposing webs and edges of the cover of FIG. 5 and an intervening layer of adhesive of the completed flexible splice. 10...Rack, 12...Creel, 14...
Tow, 16...Fil yarn inserter, 18...
... Comb, 20 ... Web, 22 ... Tension stand, 24 ... Roller, 26, 28 ... Oxidation furnace, 30 ... Oxidation furnace assembly, 32, 34 ...
Roller, 35...Tension stand, 36...
Winding roll, 38, 40...Roller, 42, 4
4... Heald, 46... Rapier assembly, 48
... Fill yarn, 52, 53, 54, 56, 5
8... Continuous process steps of the method of introducing the web into the oxidation furnace,
64,70,76,84,88,90... Sequential process steps of method of providing flexible splices, 66...
...Cover, 68...Web, 72...Adhesive coating, 82...Tape, 86...Adhesive coating.

Claims (1)

Claims: 1. A splice between overlapping adjacent ends of first and second elongated webs, the first web being a carbonized material and the second web being a carbonized material of the first web. a substantially high temperature resistant material different from a carbonaceous material; said splice includes a first layer of adhesive bonding a first surface of one end of the first web to one end of the second web; a second surface of one end of the first web by a second layer of adhesive so as to be substantially coextensive with the end of the second web on the opposite side of the one end of the second web; a second web bonded thereon, extending beyond one end of the first web, overlapping, and along a relatively small portion of the length of the second web by a second layer of adhesive; A flexible, heat resistant splice of opposed elongated webs, characterized in that the splice is provided by a length of heat resistant material adhered to the webs. 2. preparing a cover of flexible material; applying a first adhesive coating to a portion of a second elongated web of flexible material adjacent an edge thereof; placing an end of the first elongated web on the first adhesive coating; applying a second adhesive coating to the underside of the cover; and applying a second adhesive coating to the underside of the cover. placing a cover over the first web such that the cover is in contact with the first web and the cover is on the opposite side of the first web from the second web; A method of joining a first elongated web and a second elongated web of flexible material.