Method of forming crimps in high tensile modulus filaments

Satisfactory crimps are formed in high tensile modulus filaments having a tensile modulus of elasticity of 5,000 kg/mm.sup.2 or more by mixing the high tensile modulus filaments with additional filaments having a tensile modulus of elasticity of 3,000 kg/mm.sup.2 or less, and compression crimping the mixed filaments.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to a method of forming crimps in high tensile 
modulus filaments. More particularly, the present invention relates to a 
method of forming crimp in artificial filaments having a high tensile 
modulus of elasticity of 5,000 kg/mm.sup.2 or more, by a compression 
crimping procedure, to provide crimped high tensile modulus filaments 
which can be connected to staple fibers having an enhanced spinning 
property. 
(2) Description of the Related Arts 
It is known that artificial crimps can be imported to artificial filaments 
by a compression crimping method or a gear crimping method. It is also 
known that, from the view point of productivity, the compression crimping 
method using a stuffing box is best utilized, and accordingly, attempts 
have been made to crimp artificial high tensile modulus filaments, for 
example, para-type aramide filaments having a tensile modulus of 
elasticity of 7100 kg/mm.sup.2, by the compression crimping method using 
the stuffing box. 
Where the compression crimping procedure is applied to a tow of the high 
tensile modulus filaments in a compression crimping apparatus, it is often 
found that, a short time after the start of the crimping procedure, the 
bundling condition of the filament tow supplied to the crimping apparatus 
is in disorder and at the same time, shaking of the crimping apparatus 
occurs, and thus the crimping procedure cannot be continued. Also, the 
resultant crimped filaments have unsatisfactory crimping properties, and 
thus are not practically usable. 
Where the same crimping procedure as mentioned above was applied to other 
high tensile modulus filaments, for example, steel filaments having a 
tensile modulus of elasticity of 20,000 kg/mm.sup.2 and glass filaments 
having a tensile modulus of elasticity of 7,000 kg/mm.sup.2 shaking of the 
crimping apparatus occurred in the same manner as mentioned above and the 
resultant crimped filaments exhibited unsatisfactory crimping properties. 
When the crimped high tensile modulus filaments were subjected to a 
spinning procedure in the form of staple fibers, it was found that a lap 
of the fibers was wound around a carding roll, and thus the spinning 
procedure could not be continued. 
Accordingly, the provision of an effective method of imparting satisfactory 
crimps to high tensile modulus filaments by using a compression crimping 
apparatus is strongly desired. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a method of forming crimps 
in high tensile modulus filaments, at a high efficiency and productivity. 
Another object of the present invention is to provide a method of forming 
crimps in high tensile modulus filaments, which method can be continuously 
carried out by using a compression crimping apparatus, without shaking of 
the apparatus and disorder of the filaments. 
A further object of the present invention is to provide crimped high 
tensile modulus filaments having satisfactory stable crimps and usable for 
producing high tensile modulus staple fibers having an enhanced spinning 
property. 
The above-mentioned objects are attained by the method of the present 
invention comprising the steps of mixing a plurality of high tensile 
modulus filaments having a tensile modulus of elasticity of 5,000 
kg/mm.sup.2 or more with a plurality of additional filaments having a 
tensile modulus of elasticity of 3,000 kg/mm.sup.2 or less; and 
compression crimping the resultant mixed filaments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the present invention, it was found that the additional filaments having 
a tensile modulus of elasticity of 3000 kg/mm.sup.2 or less and mixed with 
the high tensile modulus filaments having a tensile modulus of elasticity 
of 5,000 kg/mm.sup.2 or more, are effective for imparting satisfactorily 
stable crimps to the high tensile modulus filaments under crimping 
conditions in which the high tensile modulus filaments cannot be 
satisfactorily crimped in the absence of the additional filaments. 
The high tensile modulus filaments usable for the present invention are 
preferably selected from the group consisting of 
poly-p-phenylene-terephthalamide filaments, for example, those available 
under the trademark of Kevlar, made by Du Pont; 
copoly-p-phenylene/3,4'-oxydiphenylene terephthalate filaments, for 
example, those available under the trademark of Technola, made by Teijin 
Ltd; glass filament and steel filaments having a tensile modulus of 
elasticity of 5,000 kg/mm.sup.2 or more; and mixtures of at least two 
types of the above-mentioned filaments. 
The additional filaments usable for the present invention are preferably 
selected from the group consisting of viscose rayon filaments, cupra rayon 
filaments, aliphatic polyamide filaments, for example, nylon 6 and nylon 
66 filaments, polyacrylic filaments, polyester filaments, for example, 
polyethylene terephthalate filaments, water-insoluble modified polyvinyl 
alcohol filaments, poly-m-phenylene isophthalamide filaments and 
polybenzimidazole filaments having a tensile modulus of elasticity of 
3,000 kg/mm.sup.2 or less, and mixtures of at least two types of the 
above-mentioned filaments. 
In the method of the present invention, a plurality of the high tensile 
modulus filaments is mixed with a plurality of the additional filaments to 
provide the mixed filaments to be crimped. 
In the mixed filaments, the content of the additional filaments is 
preferably 40% to 98% by weight, more preferably 60% to 98% by weight. 
When the content of the additional filaments in the mixed filaments is more 
than 98% by weight (the content of the high tensile modulus filaments is 
less than 2% by weight) the amount of the resultant crimped high tensile 
modulus filaments is very small, and therefore, when the crimped high 
tensile modulus filaments are separated from the additional filaments, a 
very small yield of the separated crimped high tensile modulus filaments 
is obtained, and thus the process is very costly. Also, when the crimped 
mixed filaments are used without the separation, for example, for the 
preparation of mixed staple fibers to be converted to spun yarns, the 
contribution of the crimped high tensile modulus staple fibers to various 
properties, for example, tensile strength, of the spun yarns is 
unsatisfactory. 
When the content of the addition filaments in the mixed filaments is less 
than 40% by weight, the contribution of the additional filaments to the 
formation of crimps in the high tensile modulus filaments is 
unsatisfactory. 
The high tensile modulus filaments and the additional filaments to be used 
for the method of the present invention preferably have a denier of the 
individual filament of from 0.5 to 10. 
The mixed filaments are subjected to a compression crimping procedure, 
preferably by using a stuffing box. Before the compression crimping 
procedure, the mixed filaments are preferably conditioned at a temperature 
of from 60.degree. C. to 100.degree. C. and in an average moisture content 
of 10% by weight or more. 
The temperature of 60.degree. C. to 100.degree. C. imparted to the mixed 
filaments under wet condition effectively decreases the Young's modulus of 
the additional filaments, to promote the compression buckling of the 
filaments and thus the formation of crimps therein, and to form acute 
compression buckling angles of the filaments. 
The moisture content of 10% by weight or more is effective not only for 
swelling the filaments to cause a decrease of the secondary transition 
point and the Young's modulus of the filament, but also for promoting the 
bundling of the mixed filaments and stability of the crimping procedure 
applied to the mixed filaments. 
Generally, the mixed filaments are in the form of a tow, and the tow of 
mixed filaments preferably has a total denier of 40,000 per 25 mm of the 
width of a feed nip roller through which the tow is fed into the 
compression crimping apparatus. An excessively small total denier of the 
tow sometimes causes an undesirable shaking of the compression crimping 
apparatus. 
Usually, the tow of the mixed filaments is fed to the compression crimping 
apparatus at a speed of 5 to 300 m/min, but this is variable depending on 
the type and thickness of the filaments in the tow. 
In the compression crimping apparatus, the mixed filaments are compression 
buckled to form crimps therein, and preferably, heat-set at a temperature 
of 80.degree. C. or more, more preferably 100.degree. C. or more, still 
more preferably 100.degree. C. to 180.degree. C., at which the filaments 
are not fuse-bonded to each other, and the moisture retained in the mixed 
filaments is evaporated as quickly as possible. 
If the compression buckling angles imparted to the mixed filaments increase 
during the compression crimping procedure, the resultant crimps on the 
mixed filaments are unsatisfactory. Therefore, to prevent an increase in 
the buckling angles of the mixed filaments, preferably the mixed filaments 
in the compression crimping apparatus are heat-set at a packing density of 
0.5 g/cm.sup.2 or more. 
The method of the present invention will be further explained with 
reference to FIG. 1. 
Referring to FIG. 1, a tow A of additional filaments having a tensile 
modulus of elasticity of 3000 kg/mm.sup.2 or less is mixed at a pair of 
feed rollers 2 with a tow B of high tensile modulus filaments supplied 
from a roll 1, to form a mixed filament tow C. The mixed filament tow C is 
oiled in an oiling bath 3, squeezed by a pair of nip rollers 4, and then 
conditioned by steam in a conditioning box 5 at a predetermined 
temperature and a predetermined moisture content. The conditioned mixed 
filament tow C is fed through a pair of pushing rollers 6 into a 
compression crimping box, for example, a stuffing box 7, equipped with a 
heater 8. The mixed filaments are packed at a packing density of 0.5 
g/cm.sup.2 or more, compression buckled in the stuffing box 7 to form 
crimps therein, and heat set at a temperature of 80.degree. C. or more by 
the heater 8. 
The resultant crimped mixed filament tow D is delivered to a can 9. 
The procedure of mixing the high tensile modulus filament tow B with the 
additional filament tow A can be effected at any point upstream of the 
pushing rollers 6, but since it is preferable to apply the conditioning 
procedure to the mixed filament tow C before the compression crimping 
procedure, the mixing procedure is preferably effected at any point 
upstream of the conditioning box 5. 
The mixing procedure is not limited, but preferably the high tensile 
modulus filaments are evenly mixed with the additional filaments so that, 
in a transverse view of the resultant mixed filament tow, the high tensile 
modulus filaments are evenly distributed in the mixed filament tow. This 
even mixing effectively prevents the generation of shaking of the 
compression crimping apparatus. 
The oiling procedure in the oiling bath 3 effectively imparts predetermined 
amounts of an oiling agent and water to the mixed filaments. The oiling 
agent usable for the method of the present invention can be selected from 
usual oiling agents for staple fibers to be spun or to be converted to a 
non-woven fabric by a dry webbing method. 
The oiling agent and the moisture imparted to the mixed filaments 
contribute to a stabilizing of the compression crimping procedure. 
As stated above, the average moisture content of the mixed filaments is 
preferably 10% by weight or more, more preferably 10% to 30% by weight. 
The compression crimping procedure is carried out so that crimps are formed 
in the high tensile modulus filaments, preferably at a number of 10 
crimps/25 mm or more and at a crimp percentage of 10% or more. 
The resultant crimped mixed filaments composed of the high tensile modulus 
filaments and the additional filaments can be used without separation. 
Namely, when the mixed crimped mixed filaments are cut to a predetermined 
length, the resultant crimped mixed staple (short) fibers can be used to 
provide non-woven fabrics or spun yarns. 
Alternatively, the crimped high tensile modulus filaments in the mixed 
filaments are separated from the crimped additional filaments, and the 
separated crimped high tensile modulus filaments and additional filaments 
are then cut separately to predetermined lengths. The length of the 
resultant cut filaments is usually from 32 to 153 mm. The cut high tensile 
modulus filaments and additional filaments are separately subjected to 
predetermined uses, for example, spun yarns or non-woven fabrics by a dry 
webbing method. 
The separation of the high tensile modulus filaments from the additional 
filaments can be effected by any separating apparatus. 
Referring to FIG. 2, which shows an embodiment of the filament-separating 
apparatus, a crimped mixed filament tow D is fed through a pair of feed 
rollers 11 and divided into a tow E of crimped high tensile modulus 
filaments and a tow F of crimped additional filaments, respectively, 
through a swing roller 12 and a swing roller 13, which are vertically 
movable in the direction shown by arrows. The separated high tensile 
modulus filament tow E is taken up to a cutter 16 through guide rollers 14 
and 15 and cut by the cutter 16 to a predetermined length to provide 
crimped high tensile modulus stable fibers. 
The additional filament tow F is taken up to a cutter 19 through guide 
rollers 17 and 18 and cut by the cutter 17 to a predetermined length. 
To smoothly separate the crimped high tensile modulus filament tow E from 
the crimped additional filament tow F, preferably the taking-up speeds of 
the tows E and F to the cutters 16 and 19 are controlled to a level 
slightly higher than the feeding speed thereof to the feed roller 11. The 
taking-up speeds of the tows E and F to the cutters 16 and 19 are 
respectively controlled in accordance with the tensions of the tows on the 
swing rollers 12 and 13. Namely, the tensions created on the tows E and F 
can be controlled by controlling the taking-up speeds of the tows E and F 
into the cutters 16 and 19, respectively. 
If the numbers of crimps in the crimped mixed filaments are less than 10 
crimps/25 mm, and/or the crimp percentages thereof are less than 10%, they 
cannot be always satisfactory opened in the scotching and carding 
procedures, and thus cannot be evenly mixed with each other. Therefore, 
the resultant mixed spun yarns have an uneven composition, structure, and 
properties thereof. 
Also, if the separated crimped high tensile modulus filaments have less 
than 10 crimps/25 mm and/or a crimp percentage of less than 10%, the 
filaments cannot be satisfactorily opened in the scotching and carding 
procedures, the filaments are often wound around the carding cylinder, and 
a large amount of fiber dust is formed in the carding procedure so that 
the spinning procedures must be often interrupted. 
The crimped high tensile modulus filaments produced in accordance with the 
method of the present invention have similar crimping properties to those 
of usual filaments having a relatively low tensile modulus and can be used 
independently or together with ordinary relatively low tensile modulus 
filaments, without difficulty, to provide spun yarns or non-woven fabrics. 
EXAMPLES 
The present invention will be further explained by way of specific 
examples, which are representative and do not in any way restrict the 
scope of the present invention. 
Example 1 and Comparative Example 1 
In Example 1, a tow A of additional filaments was prepared from 163,900 
poly-m-phenylene isothalamide filaments available under a trademark of 
Teijinconex, made by Teijin Ltd., produced through wet-spinning, drawing, 
and heat-setting procedures, having a denier of the individual filaments 
of 1.5 and a tensile modulus of elasticity of 990 kg/mm.sup.2, and oiled 
with an oiling agent. 
A tow B of crimped high tensile modulus filaments was provided from 70,000 
copoly-p-phenylene/3,4'-oxydiphenylene terephthalamide filaments available 
under a trademark of Technola, made by Teijin Ltd., and having a tensile 
modulus of elasticity of 7100 kg/mm.sup.2 and a denier of individual 
filaments of 1.5. 
The tow A in an amount of 70 parts by weight was evenly mixed with 30 parts 
by weight of the tow B to provide a mixed filament tow having a total 
denier of 350,000, and the mixed filament tow then oiled with a 
conventional oiling agent. The mixed and oiled filament tow was 
conditioned at a temperature of 75.degree. C. and a moisture content of 
12%, fed to a compression crimping machine equipped with a pair of feed 
rollers having an effective width of 100 mm, and compression-crimped at a 
crimping speed of 20 m/min at a temperature of 95.degree. C. and a packing 
density of 0.84 g/cm.sup.3. The crimped mixed filament tow was cut to a 
length of 51 mm, and the resultant cut high tensile modulus filaments 
(Technola) and additional filament (Teijinconex) had the crimping 
properties as shown in Table 1. 
The compression crimping procedure was continuously and stably carried out 
for 24 hours. During the 24 hour continuous operation, shaking occurred 
only once in the compression crimping apparatus. 
TABLE 1 
______________________________________ 
(Example 1) 
Number 
of crimps 
Crimp 
Content per percent- 
Filament Item (% wt.) 25 mm age (%) 
______________________________________ 
High tensile modulus 
filaments 
30 11.2 15.3 
(Technola) 
Additional filaments 70 11.4 16.1 
(Teijinconex 
______________________________________ 
In Comparative Example 1, the same procedures as in Example 1 were carried 
out except that additional filaments were not added and the total denier 
of the high tensile modulus filament tow was adjusted to 350,000. 
The resultant crimped high tensile modulus fibers had a length of 51 mm and 
the unsatisfactory crimping properties shown in Table 2. 
The crimping step was unstable and one minute after the state of the 
crimping step, shaking of the apparatus occurred. 
TABLE 2 
______________________________________ 
(Comparative Example 1) 
Number 
of crimps 
Crimp 
Content per percent- 
Filament Item (% wt) 25 mm age (%) 
______________________________________ 
High tensile modulus 
filaments 
100 8.1 7.2 
(Technola) 
______________________________________ 
Examples 2 to 4 and Comparative Example 2 
In Example 2, the same procedures as those in Example 1 were carried out 
except that the copoly-p-phenylene/3,4'-oxydiphenylene terephthalate 
filaments were replaced by steel filaments having a denier of the 
individual filament of 2.5 and a tensile modulus of elasticity of 20,000 
kg/mm.sup.2. 
In Example 3, the same procedures as in Example 2 were carried out except 
that the steel filaments were replaced by glass filaments having a denier 
of the individual filament of 1.7 and a tensile modulus of elasticity of 
7,000 kg/mm.sup.2. 
In Example 4, the same procedures as in Example 2 were carried out except 
that the steel filaments were replaced by poly-p-phenylene terephthalamide 
filaments available under a trademark of Kevlar made by Du Pont, having a 
denier of the individual filament of 1.5 and a tensile modulus of 
elasticity of 5900 kg/mm.sup.2. 
In Comparative Example 2, the same procedures as those in Example 2 were 
carried out except that additional filaments were not used and the tow of 
the steel filaments was adjusted to a total denier of 350,000. 
In each of Examples 2 to 4 and Comparative Example 2, the stability of the 
continuous compression crimping procedure for 24 hours was observed and 
evaluated in the following classes. 
______________________________________ 
Class Note (in 24 hour continuous operation) 
______________________________________ 
5 shaking of the apparatus generated two 
times or less 
4 shaking of the apparatus generated 3 to 
10 times 
3 shaking of the apparatus generated 11 
times or more 
2 shaking of the apparatus generated within 
one minute to 5 minutes from start of 
crimping operation 
1 shaking of the apparatus generated within 
one minute from start of crimping 
operation. 
______________________________________ 
The results are shown in Table 3. 
The resultant cut high tensile modulus fibers having a length of 51 mm 
exhibited the crimping properties shown in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Component High tensile modulus 
High tensile filament 
Item modulus 
Additional 
Stability Crimp 
Example 
filament 
filament 
of crimping 
Number of 
percentage 
No. (wt %) (wt %) operation 
crimps/25 mm 
(%) 
__________________________________________________________________________ 
Example 2 
Steel Teijinconex 
4 10.3 13.8 
(30) (70) 
Example 3 
Glass Teijinconex 
5 10.7 13.9 
(30) (70) 
Example 4 
Kevlar Teijinconex 
5 11.0 14.6 
(30) (70) 
Comparative 
Steel -- 1 8.2 8.0 
Example 2 
(100) 
__________________________________________________________________________ 
Examples 5 to 7 and Comparative Example 3 
In Example 5, 40 parts by weight of high tensile modulus filaments 
consisting of copoly-p-phenylene/3,4'-oxydiphenylene terephthalamide 
filaments having a denier of the individual filament of 1.5 and a tensile 
modulus of elasticity of 7,100 kg/mm.sup.2 and available under a trademark 
of Technola made by Teijin Ltd. were mixed with 60 parts by weight of 
additional filaments consisting of polyethylene terephthalate filaments 
produced by melt-spinning, drawing, and heat-setting procedures and having 
a denier of the individual filament of 2.0 and a tensile modulus of 
elasticity of 850 kg/mm.sup.2, to provide a mixed filament tow having a 
total denier of 400,000. 
The mixed filament tow was conditioned at a temperature of 75.degree. C. 
and a moisture content of 12%, and fed to a compression crimping procedure 
through feed rollers having an effective width of 100 mm at a crimping 
speed of 30 m/min and a packing density of 0.97 g/cm.sup.3. 
The resultant crimped mixed filament tow was dried and relaxed at a 
temperature of 120.degree. C. 
The relaxed tow was divided into a crimped high tensile modulus filament 
tow and a crimped additional filament tow, and each tow was cut to a 
length of 51 mm. 
The stability of the compression crimping procedure and the crimping 
properties of the crimped high tensile modulus filaments are shown in 
Table 4. 
In Example 6, the same procedures as in Example 5 were carried out except 
that the additional filaments consisted of nylon 66 filaments drawn in two 
steps and having a denier of the individual filament of 2.0 and a tensile 
modulus of elasticity of 420 kg/mm.sup.2. 
The stability of the compression crimping procedure and the crimping 
properties of the crimped high tensile modulus filaments are shown in 
Table 4. 
In Example 7, the same procedures as in Example 5 were carried out except 
that the additional filaments consisted of polyacrylic filaments produced 
by wet spinning, drawing and heat-setting procedures and having a denier 
of the individual filament of 3.0 and a tensile modulus of elasticity of 
510 kg/mm.sup.2. 
The stability of the compression crimping procedure and the crimping 
properties of the resultant high tensile modulus filaments are shown in 
Table 4. 
In Comparative Example 4, the same procedures as in Example 5 were carried 
out except that additional filaments were not used and the total denier of 
the high tensile modulus filament tow was adjusted to 400,000. 
The stability of the compression crimping procedure and the crimping 
properties of the resultant crimped high tensile modulus filaments are 
shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Component High tensile modulus 
High tensile filament (Technola) 
Item modulus 
Additional 
Stability Crimp 
Example 
filament 
filament 
of crimping 
Number of 
percentage 
No. (wt %) (wt %) procedure 
crimps/25 min 
(%) 
__________________________________________________________________________ 
Example 5 
Technola 
Polyester 
4 11.0 15.8 
(40) (60) 
Example 6 
Technola 
Nylon 66 
5 12.5 17.3 
(40) (60) 
Example 7 
Technola 
Polyacrylic 
5 12.3 17.5 
(40) (60) 
Comparative 
Technola 
-- 1 7.5 6.6 
Example 4 
(100) 
__________________________________________________________________________ 
Table 4 clearly indicates the following: 
In Examples 5 to 7 in accordance with the method of the present invention, 
the compression crimping procedures were stably carried out and the 
resultant crimped high tensile modulus filaments had satisfactory crimping 
properties. 
In Comparative Example 4, the compression crimping procedure was very 
unstable and the crimping properties of the resultant crimped high tensile 
modulus filaments were unsatisfactory. 
Examples 8 to 11 
In each of Examples 8 to 11, the same procedures as in Example 1 were 
carried out except that the mixing percentages of the high tensile modulus 
filaments and the additional filaments were as indicated in Table 5. 
The stability of the compression crimping procedure and the crimping 
properties of the resultant crimped high tensile modulus filaments are 
shown in Table 5, in comparison with the results of Comparative Example 1. 
TABLE 5 
__________________________________________________________________________ 
Component (wt %) 
Stability 
High tensile modulus 
High tensile of com- 
filament 
Item modulus 
Additional 
pression Crimp 
Example 
filament 
filament 
crimping 
Number of 
percentage 
No. (*)1 (*)2 procedure 
crimps/25 mm 
(%) 
__________________________________________________________________________ 
Comparative 
100 -- 1 8.1 7.2 
Example 1 
Example 8 
5 95 5 12.2 17.5 
Example 9 
40 60 5 11.1 15.5 
Example 10 
50 50 4 10.8 14.1 
Example 11 
70 30 3 10.3 13.5 
__________________________________________________________________________ 
Note: 
*1 Copolyp-phenylene/3,4oxydiphenylene terephthalamide filaments 
(Technola) 
*2 Polym-phenylene isophthalamide filaments (Teijinconex) 
Table 5 indicates that the crimping properties of the crimped high tensile 
modulus filaments produced in Examples 8 to 11 in accordance with the 
method of the present invention are superior to those of Comparative 
Example 1. 
In view of the results of Examples 8 to 11, the crimping properties of the 
crimped high tensile modulus filaments decrease with an increase in the 
content of the high tensile modulus filaments in the mixed filaments. 
Especially, preferably the content of the high tensile modulus filaments 
in the mixed filaments is 40% by weight or less but not less than 2% by 
weight. 
Examples 12 to 16 
In each of Examples 12 to 16, a mixed filament tow having a total denier of 
480,000 was prepared by mixing 10 parts by weight of high tensile modulus 
filaments consisting of copoly-p-phenylene/3,4'-oxydiphenylene 
terephthalamide filaments (Technola) having a denier of the individual 
filament of 1.5 and a tensile modulus of elasticity of 7,100 kg/mm.sup.2 
with 90 parts by weight of additional filaments consisting of 
poly-m-phenylene isophthalamide filaments (Teijinconex) having a denier of 
the individual filament of 2.0 and a tensile modulus of elasticity of 950 
kg/mm.sup.2. 
The mixed filament tow was oiled with an oiling agent and conditioned at 
the temperature and moisture content indicated in Table 6, by blowing 
steam. 
The conditioned mixed filament tow was fed to a compression crimping 
apparatus through a feed nip roller having an effective feed width of 120 
mm and compression crimped therein at a crimping speed of 15 m/min at a 
packing density of 0.5 g/cm.sup.3 or more and at the temperature indicated 
in Table 6. 
The crimped mixed filament tow was cut to a length of 51 mm. 
The stability of the compression crimping procedure and the crimping 
properties of the resultant crimped high tensile modulus filaments are 
indicated in Table 6. 
TABLE 6 
__________________________________________________________________________ 
Conditioning Crimping 
Stability of 
High tensile modulus 
Item Moisture 
Temper- 
temper- 
compression 
filament 
Example 
content 
ature 
ature 
crimping 
Number of 
Crimp per- 
No. (%) (.degree.C.) 
(.degree.C.) 
procedure 
crimps/25 mm 
centage (%) 
__________________________________________________________________________ 
12 8 50 60 3 11.3 15.0 
13 8 65 70 4 11.8 16.5 
14 12 65 70 5 12.0 17.1 
15 12 75 80 5 12.5 18.2 
16 12 75 95 5 12.5 19.0 
__________________________________________________________________________ 
Table 6 shows that the crimping properties of the crimped high tensile 
modulus filaments increase with increases in the moisture content and 
temperature of the conditioned mixed filament tow, and with an increase in 
the temperature of the mixed filament tow in the compression crimping 
apparatus. Also, the stability of the compression crimping procedure 
increases with increases in the moisture content and temperature of the 
conditioned mixed filament tow. 
Example 17 
The same procedures as in Example 1 were carried out, and the resultant 
crimped mixed filament tow was cut to provide mixed staple fibers having a 
length of 51 mm. 
The resultant mixed staple fibers were subjected to usual spinning 
procedures, and it was found that, in the scotching and carding steps, the 
mixed staple fibers were satisfactory opened, and the amount of 
undesirable floating fiber dust produced in the carding step was very 
small. Also, the resultant spun yarns had a satisfactory uniform thickness 
and quality thereof. 
Examples 18 and 19 and Comparative Example 4 
In each of Examples 18 and 19 and Comparative Example 4, the same 
procedures as in Example 1 were carried out except that the crimping 
conditions were changed so that the resultant crimped high tensile modulus 
filaments had the number of crimps and the crimp percentage shown in Table 
7. 
The resultant crimped mixed staple fibers were subjected to usual spinning 
procedures. 
The card-passing property of the crimped mixed staple fibers and the 
uniformity of the resultant sliver were evaluated as described below. 
Card-passing property 
A predetermined amount of the crimped mixed staple fibers were subjected to 
an ordinary carding procedure, at a temperature of 25.degree. C. and a 
relative humidity of 55% RH, with a feeding rate of 300 grains/6 yards at 
a rotation rate of 14 r.p.m. 
In view of the lap-licking phenomenon, winding of the fibers on the carding 
cylinder, the amounts of fiber dust, and drooping of the sliver, the 
card-passing property of the mixed fibers were evaluated in three classes; 
"excellent", "good", and "unsatisfactory". 
Uniformity of sliver 
After a drawing step, the appearance and uniformity of the resultant sliver 
was observed by the naked eye and evaluated in three classes; "excellent", 
"good" and "unsatisfactory". 
The results are shown in Table 7. 
TABLE 7 
__________________________________________________________________________ 
High tensile modulus 
Item filament 
Example 
Number of 
Crimp per- 
Card-passing 
Uniformity of 
No. crimps/25 mm 
centage (%) 
property 
sliver 
__________________________________________________________________________ 
Example 18 
11.1 13.2 Excellent 
Excellent 
Example 19 
10.3 10.7 Good Good 
Comparative 
9.0 9.4 Unsatisfactory 
Unsatisfactory 
Example 4 
__________________________________________________________________________