A process for re-shaping a previously pultruded thermoplastic article having a first longitudinal cross-sectional area and a first longitudinal cross-sectional configuration into a new thermoplastic article having approximately the same longitudinal cross-sectional area but a substantially different longitudinal cross-sectional configuration.

BACKGROUND OF THE INVENTION 
1. Field of the Invention. 
This invention relates to processes for producing reinforced plastic 
articles, and more particularly, to processes for pultruding fiber 
reinforced thermoplastic articles. 
2. 2. Description of the Prior Art. 
Processes for producing fiber reinforced plastic articles by the technique 
of pultrusion are well known. In such a process, prepreg feed material 
comprising a plurality of reinforcing fiber strands surrounded by a resin 
matrix is pulled through a heated forming die. Common types of articles 
produced by pultrusion processes include channels, rods, bars and slats. 
Although pultrusion processes were limited to the use of thermoset resins 
at one time, pultrusion processes for forming reinforced plastic articles 
from thermoplastic resins have now been developed. 
Most pultrusion processes can be characterized as either wet or dry. In a 
wet pultrusion process, a plurality of fiber strands are pulled from a 
creel and through a resin bath for impregnation of the strands with the 
resin. Typically, excess resin is then removed from the strands. The resin 
impregnated fiber strands, now referred to as "prepreg feed material", are 
then pulled through a heated forming die and cooled to form a plastic 
composite or article of a continuous length. The article is typically cut 
into long portions which are either stored or transported elsewhere for 
further processing. 
Dry pultrusion processes do not include the step of passing a plurality of 
fiber strands through a resin bath and the other steps associated with 
initially forming the resin impregnated fiber strands or prepreg feed 
material. In a dry pultrusion process, the prepreg feed material fed into 
the heated forming die is pre-impregnated material formed in a separate 
process. Such pre-impregnated material can be, for example, unidirectional 
tape or fabric prepreg. As in wet pultrusion processes, the prepreg feed 
material is pulled through a heated forming die and cooled to form an 
article of continuous length. 
By the present invention, it has been discovered that a previously 
pultruded article having a substantially different shape than the final 
product can be employed as the prepreg feed material fed into the heated 
forming die in a dry pultrusion process. As long as it has approximately 
the same longitudinal cross-sectional area or volume, the prepreg feed 
material can have any longitudinal cross-sectional configuration. In this 
way, previously pultruded articles such as rods can be re-pultruded into 
different articles such as bars or various types of beams. This expands 
the utility of pultrusion processes in general and expands the utility of 
the articles produced thereby. 
SUMMARY OF THE INVENTION 
The present invention provides a process for re-shaping a previously 
pultruded elongated thermoplastic article having a particular longitudinal 
cross-sectional area and a particular longitudinal cross-sectional 
configuration into a new elongated thermoplastic article having 
approximately the same longitudinal cross-sectional area and a 
substantially different longitudinal cross-sectional configuration. The 
process comprises the steps of pulling the previously pultruded article 
into an elongated die, the die comprising a final forming zone having a 
longitudinal cross-sectional area approximately equal to the longitudinal 
cross-sectional area of the previously pultruded article and a 
longitudinal cross-sectional configuration substantially different from 
the longitudinal cross-sectional configuration of the previously pultruded 
article, applying sufficient heat to the previously pultruded article to 
soften the article sufficiently to permit it to be re-shaped, and pulling 
the previously pultruded article through the final forming zone of the die 
whereby the article is re-shaped to have a longitudinal cross-sectional 
area and a longitudinal cross-sectional configuration approximately equal 
to the longitudinal cross-sectional area and longitudinal cross-sectional 
configuration of the forming zone of the die. Thus, the present invention 
provides a process for pultruding a new thermoplastic article having a 
particular longitudinal cross-sectional area and a particular longitudinal 
cross-sectional configuration wherein the feed prepreg material employed 
in the process is a previously pultruded thermoplastic article having a 
longitudinal cross-sectional area approximately equal to the longitudinal 
cross-sectional area of the new thermoplastic article and a longitudinal 
cross-sectional configuration substantially different from the 
longitudinal cross-sectional configuration of the new thermoplastic 
article. 
In a particular embodiment of the process of the present invention, a new 
thermoplastic article is formed by the steps of pulling thermoplastic feed 
prepreg material through a first heated elongated die comprising a final 
forming zone having a first longitudinal cross-sectional area and a first 
longitudinal cross-sectional configuration to form a first thermoplastic 
article having a longitudinal cross-sectional area and a longitudinal 
cross-sectional configuration approximately equal to the first 
longitudinal cross-sectional area and the first longitudinal 
cross-sectional configuration, allowing the first thermoplastic article to 
harden, and pulling the first thermoplastic article through a second 
heated elongated die comprising a final forming zone having a second 
longitudinal cross-sectional area approximately equal to the first 
longitudinal cross-sectional area and a second longitudinal 
cross-sectional configuration substantially different from the first 
longitudinal cross-sectional configuration to form a thermoplastic article 
having a longitudinal cross-sectional area approximately equal to the 
second longitudinal cross-sectional area and a longitudinal 
cross-sectional configuration approximately equal to the second 
longitudinal cross-sectional configuration. 
It is, therefore, a principal object of the present invention to provide a 
new pultrusion process. 
It is an object of the present invention to provide a process for 
re-shaping a previously pultruded thermoplastic article having a 
particular shape into a new thermoplastic article having a substantially 
different shape. 
It is an object of the present invention to provide a new pultrusion 
process whereby unneeded thermoplastic articles can be re-shaped into 
needed thermoplastic articles. 
A further object of the present invention is to provide a pultrusion 
process wherein new thermoplastic articles are pultruded in the absence of 
slurry baths, drying chambers and other process equipment required to form 
the initial prepreg feed material. 
Other objects, features, uses and advantages of the present invention will 
be readily apparent to those skilled in the art upon a reading of the 
following description of the preferred embodiments of the present 
invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As used herein and in the appended claims, "substantially different 
longitudinal cross-sectional configuration" means substantially different 
shape or profile, e.g., a rod as opposed to a bar. Thus, a forming zone of 
a die having a longitudinal cross-sectional configuration substantially 
different from the longitudinal cross-sectional configuration of a bar 
would be a forming zone of a die having the longitudinal shape or profile 
of, for example, a rod or a top hat. An article having a longitudinal 
cross-sectional configuration substantially different from the 
longitudinal cross-sectional configuration of a channel would be, for 
example, a slat. 
Referring now to FIG. 1, a prior art apparatus for pultruding reinforced 
plastic articles is illustrated and generally designated by the numeral 
10. 
A single fiber strand or a multiplicity of fiber strands are pulled from a 
creel 14 through a roving guide 16 and through a resin slurry bath 18. In 
the resin slurry bath 18, the fibers are impregnated with a plastic resin 
20. If desired, a dry resin powder can be substituted for the resin slurry 
in the resin bath 18. 
The fiber strands are passed around a plurality of redirect bars 22 as they 
are pulled through the resin slurry bath 18 to spread the strands in the 
bath. If desired, the fibers can be sprayed by a spray nozzle 24 with a 
flow of gaseous fluid before they are pulled through the resin slurry bath 
18. The flow of gaseous fluid is sprayed into contact with the fiber 
strands with sufficient velocity to spread the individual strands so that 
single filaments or bundles of single filaments are separated. Separation 
of the fiber strands prior to or in the resin slurry bath 18 allows better 
contact of the fiber with the resin. 
After passing through the resin slurry bath 18, the impregnated fiber 
strands are pulled through a guide mechanism 23 and through a heated 
drying chamber 26. The heated drying chamber 26 removes the slurry diluent 
from the impregnated fiber strands leaving prepreg feed material ready to 
be formed into the desired shape. 
In an alternate embodiment, the creel 14, resin slurry bath 18, drying 
chamber 26 and other apparatus used to initially form the prepreg feed 
material are replaced by prepreg feed material supply means 30. The 
prepreg feed material supply means 30 provides pre-impregnated prepreg 
feed material that is formed in a separate process. The pre-impregnated 
prepreg feed material can be, for example, unidirectional tape or fabric 
prepreg. 
After being pulled from the heated drying chamber 26, or alternatively, the 
prepreg feed material supply means 30, the prepreg feed material is pulled 
through a heated elongated forming die 36. If desired, the prepreg feed 
material can be pulled through other process apparatus such as a 
preheating chamber and a shape preformer before being pulled into the 
forming die 36. The prepreg feed material, now a formed thermoplastic 
article having a particular longitudinal cross-sectional area and a 
particular longitudinal cross-sectional configuration, is pulled out of 
the forming die 36 and into a cooling die 38. In the cooling die 38, the 
formed thermoplastic article is cooled at a rate sufficient to harden the 
article whereby the article retains the particular longitudinal 
cross-sectional configuration provided to it by the forming die 36. A 
gripping or pulling mechanism 40 is used to pull the reinforcing fibers 
and thermoplastic matrix through the resin bath 18, forming die 36, 
cooling die 38 and other process apparatus. After passing through the 
pulling mechanism 40, the formed thermoplastic article is cut into desired 
lengths by a cutting device 42. Typically, the article is cut into long 
lengths and stored or transported for further processing. In an alternate 
embodiment, the formed thermoplastic article can be wound upon a rotating 
mandrel. The wound article can be reheated and unwound at another 
destination or can be used to form hollow shaped objects. 
As will be understood by those skilled in the art, the above-described 
pultrusion apparatus and process can be modified in many ways. A great 
deal of additional apparatus and steps can be employed. The particular 
apparatus and steps employed will depend, to a large extent, on the 
particular nature and shape of the article being formed. A pultrusion 
process for forming fiber reinforced poly(arylene sulfide) articles is 
disclosed in U.S. Pat. No. 4,680,224, issued July 14, 1987 and assigned to 
the assignee of the present application, which is incorporated by 
reference herein. 
Referring now to FIGS. 2-4, a prior art forming die is illustrated and 
generally designated by the numeral 50. The die 50 is equipped with means 
for providing heat to the die and hence to the article (not shown), and a 
plurality of thermocouples 52 for monitoring the temperature throughout 
the length thereof. The means for providing heat to the die and hence to 
the article can comprise, for example, a plurality of electric strip 
heaters attached to the die. The die 50 comprises a single cavity 54 
having a funnel-shaped mouth 56, an initial forming zone 57 and a final 
forming zone 58. The funnel-shaped mouth 56 allows for easier entrance of 
the fiber strands into the cavity 54. The initial forming zone 57 is 
tapered from the funnel-shaped mouth 56 to the final forming zone 58 to 
allow for gradual compaction of the fiber strands as they pass 
therethrough. The final forming zone 58 has a constant longitudinal 
cross-sectional area or volume 60 and a constant longitudinal 
cross-sectional configuration 62. The longitudinal cross-sectional 
configuration 62 of the final forming zone 58 replicates the longitudinal 
cross-sectional configuration of a bar. 
FIG. 5 illustrates a bar 64 formed by the forming die 50. As shown, the bar 
64 has a longitudinal cross-sectional area 68 and a longitudinal 
cross-sectional configuration 70 that are approximately equal to the 
longitudinal cross-sectional area 60 and longitudinal cross-sectional 
configuration 62 of the final forming zone 58 of the cavity 54 of the die 
50. 
As will be understood by those skilled in the art, the longitudinal 
cross-sectional area and the longitudinal cross-sectional configuration of 
the initial forming zone 57 and the final forming zone 58 of the cavity 54 
of the forming die 50 can vary. The longitudinal cross-sectional area will 
vary depending upon the size of the composite or article that is formed. 
The longitudinal cross-sectional configuration will vary depending upon 
the type of composite or article that is formed. For example, the 
longitudinal cross-sectional configuration of the final forming zone 58 
and the composites produced therefrom can be that of a bar, a rod, a 
channel, a slat, an "I"-shaped beam, a "top hat"-shaped beam, a 
"rectangular"-shaped beam, a "T"-shaped beam, a "J"-shaped beam, a 
"G"-shaped beam, a "L"-shaped beam and the like. 
In accordance with the process of the present invention, a previously 
pultruded elongated thermoplastic article having a particular longitudinal 
cross-sectional area and a particular longitudinal cross-sectional 
configuration is reshaped into a new elongated thermoplastic article 
having approximately the same longitudinal cross-sectional area but a 
substantially different longitudinal cross-sectional configuration. 
Conventional pultrusion apparatus can be employed in carrying out the 
process. 
Referring now to FIGS. 6-10, apparatus for carrying out the process of the 
present invention is illustrated and generally designated by the numeral 
100. Except for the resin slurry bath 18, drying chamber 26, and other 
apparatus used to initially form the prepreg feed material, or 
alternatively the prepreg feed material supply means 30, the apparatus 
used to carry out the process of the present invention is the same as the 
prior art apparatus illustrated in FIG. 1. The process of the present 
invention differs from prior art thermoplastic pultrusion processes only 
in that a previously pultruded article having a longitudinal 
cross-sectional area approximately equal to and a longitudinal 
cross-sectional configuration substantially different from the new 
thermoplastic article formed by the process is employed as the prepreg 
feed material fed into the heated forming die used to form the new 
thermoplastic article. 
The previously pultruded thermoplastic article is first pulled into an 
elongated heated forming die 102. As shown in FIGS. 7-9, the elongated 
forming die 102 comprises a single cavity 104 having a funnel-shaped mouth 
106, an initial forming zone 107 and a final forming zone 108. The 
funnel-shaped mouth 106 allows for easy entrance of the previously 
pultruded article into the cavity 104. The initial forming zone 107 is 
tapered from the funnel-shaped mouth 106 to the final forming zone 108 to 
allow for gradual compaction of the previously pultruded article into the 
final shape. The final forming zone 108 has a constant longitudinal 
cross-sectional area 110 and a constant longitudinal cross-sectional 
configuration 112. As illustrated, the longitudinal cross-sectional 
configuration 112 of the final forming zone 108 replicates the 
longitudinal cross-sectional configuration of a rod. 
The longitudinal cross-sectional area 110 and the longitudinal 
cross-sectional configuration 112 of the final forming zone 108 can vary 
as long as the longitudinal cross-sectional area 110 is approximately 
equal to the longitudinal cross-sectional area of the previously pultruded 
article and as long as the longitudinal cross-sectional configuration 112 
is substantially different from the longitudinal cross-sectional 
configuration of the previously pultruded article. For example, the 
longitudinal cross-sectional configuration of the final forming zone 108 
and the new thermoplastic composites or articles produced therefrom can be 
that of a bar, a rod, a channel, a slat, an "I"-shaped beam, a "top 
hat"-shaped beam, a "rectangular"-shaped beam, a "T"-shaped beam, a 
"J"-shaped beam, a "G"-shaped beam, a "L"-shaped beam and the like. 
The forming die 102 is equipped with a plurality of thermocouples 114 for 
measuring the temperature throughout the length of the die. The die is 
also equipped with electrical strip heaters 116 for providing heat to the 
die. 
Once the previously pultruded article is pulled into the die 102, 
sufficient heat is applied to the article by the electric strip heaters 
116 to soften the article sufficiently to permit it to be re-shaped. After 
the previously pultruded article has been softened sufficiently to permit 
it to be re-shaped, it is pulled through the initial forming zone 107 and 
then the final forming zone 108 of the cavity 104 of the die 102 whereby 
the article is re-shaped to have a longitudinal cross-sectional area and a 
longitudinal cross-sectional configuration approximately equal to the 
longitudinal cross-sectional area and longitudinal cross-sectional 
configuration of the forming zone. 
FIG. 10 shows a rod 118 formed by pulling a previously pultruded article 
through the forming die 102. As shown, the rod 118 has a longitudinal 
cross-sectional area 120 and a longitudinal cross-sectional configuration 
122 that are approximately equal to the longitudinal cross-sectional area 
110 and the longitudinal cross-sectional configuration 112 of the final 
forming zone 108 of the cavity 104 of the die 102. As used herein and in 
the appended claims, approximately equal longitudinal cross-sectional area 
and/or configuration means a longitudinal cross-sectional area and/or 
configuration that is either identical to the longitudinal cross-sectional 
area and/or configuration of the die or article that it is being compared 
to or only slightly different from the longitudinal cross-sectional area 
and/or configuration of the die or article that it is being compared to, 
the slight difference being due to the presence of air trapped in the 
previously pultruded article and/or to slight expansion and/or contraction 
of the fiber strands and/or resin matrix during the cooling process. 
After pulling the re-shaped article from the forming die 102, the article 
is optionally pulled through a cooling die 120 to cool the article at a 
rate sufficient to harden the article whereby the article retains a 
longitudinal cross-sectional area and a longitudinal cross-sectional 
configuration approximately equal to the longitudinal cross-sectional area 
and the longitudinal cross-sectional configuration of the final forming 
zone 108 of the cavity 104 of the die 102. If desired, the re-shaped 
article can be air-cooled or cooled by pulling it through a water bath 
instead of pulling it through the cooling die 120. A gripping or pulling 
mechanism 122 is used to pull the article through the forming die 102, 
cooling die 120 and/or other apparatus employed. After passing through the 
pulling mechanism 122, the article can be cut to any desired length with a 
cutting device 124. Alternatively, the article can be wound upon a mandrel 
and shipped or further processed therewith. 
As will be understood by those skilled in the art, the nature and type of 
pultrusion apparatus used to carry out the process of the present 
invention can be modified in many ways. For example, instead of a single 
heated forming die, a series of heated forming dies can be used to 
re-shape the previously pultruded article into a new article. The 
particular apparatus employed will depend, to a large extent, on the 
particular nature and shape of the article being formed. Any type of 
pultrusion apparatus can be employed. 
Thus, in accordance with the process of the present invention, a previously 
pultruded thermoplastic article having a particular longitudinal 
cross-sectional area and a particular longitudinal cross-sectional 
configuration can be re-shaped into a different thermoplastic article 
having approximately the same longitudinal cross-sectional area but a 
substantially different longitudinal cross-sectional configuration. For 
example, the bar 64 shown in FIG. 5 can be re-shaped into the rod 118 
shown in FIG. 10. Thermoplastic articles having various shapes can be 
pultruded in the absence of slurry baths, drying chambers and other 
equipment required to initially form the prepreg feed material. A supply 
of unneeded previously pultruded thermoplastic articles in storage can be 
transformed into a supply of needed thermoplastic articles. 
The process of the present invention can be combined with conventional 
pultrusion processes to produce one or more new thermoplastic articles. 
For example, a new thermoplastic article can be formed by pultruding a 
first thermoplastic article having one longitudinal cross-sectional 
configuration, and then re-pultruding the first thermoplastic article to 
form a second thermoplastic article having a substantially different 
longitudinal cross-sectional configuration. First, thermoplastic prepreg 
feed material is pulled through a first heated elongated die comprising a 
final forming zone having a first longitudinal cross-sectional area and a 
first longitudinal cross-sectional configuration to form a first 
thermoplastic article having a longitudinal cross-sectional area and a 
longitudinal cross-sectional configuration approximately equal to the 
first longitudinal cross-sectional area and the first longitudinal 
cross-sectional configuration. Next, before or after it hardens, the first 
thermoplastic article is pulled through a second heated elongated die 
comprising a final forming zone having a second longitudinal 
cross-sectional area approximately equal to the first longitudinal 
cross-sectional area and a second longitudinal cross-sectional 
configuration substantially different from the first longitudinal 
cross-sectional configuration to form a new thermoplastic article having a 
longitudinal cross-sectional area approximately equal to the second 
longitudinal cross-sectional area and a longitudinal cross-sectional 
configuration approximately equal to the second longitudinal 
cross-sectional configuration. 
Thus, a first thermoplastic article such as the bar 64 shown in FIG. 5 can 
be formed by pulling thermoplastic prepreg feed material through a forming 
die such as the die 50 shown in FIGS. 2-4. The first thermoplastic article 
can then be pulled through a second heated elongated die such as the die 
102 illustrated in FIGS. 7-9 to form a new thermoplastic article such as 
the rod 118 illustrated in FIG. 10. 
A die series can be set up that allows two different thermoplastic articles 
to be produced. For example, pultrusion apparatus such as the pultrusion 
apparatus illustrated in FIG. 1 can be combined with pultrusion apparatus 
such as the pultrusion apparatus illustrated in FIG. 6. A thermoplastic 
article having the longitudinal cross-sectional configuration of a bar can 
be pulled through the forming die 50 and cut at certain intervals to form 
a plurality of bars. In a second run, the thermoplastic article pulled 
from the die 50 can be fed directly into the forming die 102 to form a 
thermoplastic article having the longitudinal cross-sectional 
configuration of a rod which can be cut at certain intervals to form a 
plurality of rods. In this way, two types of thermoplastic articles can be 
produced in a single die series. 
The thermoplastic articles used in carrying out the process of the present 
invention and therefore the thermoplastic articles formed in accordance 
with the process of the present invention all comprise pultruded fiber 
reinforced thermoplastic articles having a longitudinal axis and at least 
one reinforcing fiber strand of continuous filaments aligned parallel to 
the longitudinal axis. The reinforcing fiber strand of continuous 
filaments is impregnated and surrounded by a continuous thermoplastic 
matrix. Inasmuch as thermoset resin cannot be re-heated and re-shaped, the 
matrix impregnating and surrounding the fiber strand or strands must be 
formed of a thermoplastic resin. 
Examples of thermoplastic resins suitable for use in forming the 
thermoplastic matrix of the thermoplastic articles used in carrying out 
the process of the present invention are polyolefins such as polypropylene 
and polyamides such as Nylon. Polyesters, polycarbonates and high 
performance thermoplastics such as polyether-ether ketone (PEEK), 
polyetherimide, polyphenylene diketone (PPDK) and liquid crystal polymers 
can also be used. Preferably, the thermoplastic resin used to form the 
matrix of the thermoplastic articles used in carrying out the process of 
the present invention comprise a poly(arylene sulfide) (PAS) polymer. More 
preferably, the thermoplastic resin used to form the matrix of the 
thermoplastic articles used in carrying out the process of the present 
invention is selected from the group consisting of poly(phenylene 
sulfide), poly(biphenylene sulfide), poly(arylene sulfide arylene ketone), 
poly(arylene sulfide arylene sulfone), and poly(ether ether ketone). 
The reinforcing fiber strand or strands of continuous filaments used to 
form the thermoplastic articles used in carrying out the process of the 
present invention and therefore the thermoplastic articles formed in 
accordance with the process of the present invention can be any fiber 
strand or strands that do not decompose prior to reaching the processing 
temperature for the thermoplastic resin used to form the matrix. 
Preferably, the reinforcing fiber strand or strands used to form the 
thermoplastic articles used in carrying out the process of the present 
invention are selected from the group consisting of carbon fiber strands, 
glass fiber strands and aramid fiber strands. 
The thermoplastic articles used in carrying out the processes of the 
present invention and thus formed in accordance with the process of the 
present invention preferably have longitudinal cross-sectional areas in 
the range of from about 0.005 square inches to about 20 square inches. 
The following example is provided to further illustrate the present 
invention. 
EXAMPLE 
This example illustrates use of the process of the present invention to 
re-shape a previously pultruded 0.5 inch by 0.1 inch bar into a 1/4 inch 
diameter rod. 
The 0.5 inch by 0.1 inch bar comprised 36 strands of carbon fiber and a 
continuous poly(phenylene sulfide) matrix impregnating and surrounding the 
strands. The bar contained in the range of from about 67.7% to about 72.1% 
by weight fiber. The bar was pultruded by pulling the fiber strands 
through a slurry bath of the polymer and then through the forming zone of 
an elongated heated die operating at 375.degree. C. 
To re-shape the bar into the rod, the bar was pulled through the forming 
zone of an elongated heated die operating at 400.degree. C. The 
longitudinal cross-sectional configuration of the forming zone was 
circular. The diameter of the final forming zone was 1/4 of an inch. The 
bar was pulled through the die at a speed of 8 inches per minute. Upon 
exiting the final forming zone of the die, the previously pultruded bar 
had the shape of a rod. The rod was cooled by pulling it through an 
elongated cooling die. The diameter of the final forming zone of the 
cooling die was 1/4 of an inch. 
Thus, the present invention can be used to re-shape a previously pultruded 
elongated thermoplastic article having a particular longitudinal 
cross-sectional area and a particular longitudinal cross-sectional 
configuration into a different elongated thermoplastic article having 
approximately the same longitudinal cross-sectional area but a 
substantially different longitudinal cross-sectional configuration. 
The preceding example can be repeated with similar success by substituting 
the generically or specifically described components, operating conditions 
and/or process equipment of the invention for those used in the example. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of the invention, and without departing from 
the scope and spirit thereof, can make various changes and modifications 
to the invention to adapt it to various usages and conditions.