U.S. patent number 3,616,184 [Application Number 04/712,447] was granted by the patent office on 1971-10-26 for titanium dioxide-containing synthetic filament having improved properties, textile products made therefrom and method of imparting said improved properties.
Invention is credited to Yasushi Katagiri, Teruo Obata, Masahiko Sugiura, Ryoichi Yasuda.
United States Patent |
3,616,184 |
Katagiri , et al. |
October 26, 1971 |
TITANIUM DIOXIDE-CONTAINING SYNTHETIC FILAMENT HAVING IMPROVED
PROPERTIES, TEXTILE PRODUCTS MADE THEREFROM AND METHOD OF IMPARTING
SAID IMPROVED PROPERTIES
Abstract
Titanium dioxide-containing synthetic filament having an
improved surface properties which contains dispersed throughout its
structure in an amount of 0.01- 1 percent by weight, based on said
filament, titanium dioxide particles consisting essentially of
particles not greater than 7 microns in particle diameter, of which
10-70 percent by weight is coarse particle titanium dioxide of 0.8-
7 microns in particle diameter, textile products made therefrom and
a method of imparting said improved properties.
Inventors: |
Katagiri; Yasushi (Nagoya,
JA), Obata; Teruo (Nagoya, JA), Sugiura;
Masahiko (Nagoya, JA), Yasuda; Ryoichi (Nagoya,
JA) |
Family
ID: |
24862151 |
Appl.
No.: |
04/712,447 |
Filed: |
March 12, 1968 |
Current U.S.
Class: |
442/202; 428/379;
524/497; 428/372; 428/395; 442/311 |
Current CPC
Class: |
C08K
3/22 (20130101); D01F 1/10 (20130101); C08K
3/22 (20130101); C08K 3/22 (20130101); C08L
77/00 (20130101); C08L 67/02 (20130101); Y10T
428/2969 (20150115); Y10T 442/3171 (20150401); Y10T
428/294 (20150115); Y10T 428/2927 (20150115); Y10T
442/444 (20150401) |
Current International
Class: |
D01F
1/10 (20060101); C08K 3/00 (20060101); C08K
3/22 (20060101); D02g 003/02 () |
Field of
Search: |
;161/174
;260/40,37,39 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sussman; Morris
Claims
We claim:
1. A titanium dioxide-containing melt-spun polyamide filament
having improved surface properties, characterized in that said
filament contains, dispersed throughout its structure in an amount
of 0.01-1 percent by weight, based on said filament, titanium
dioxide particles consisting essentially of particles not greater
than 7 microns in particle diameter, of which 1-70 percent by
weight is coarse particle titanium dioxide of 0.8-7 microns in
particle diameter, said titanium dioxide particles having a first
distribution peak in the particle size distribution in the range of
0.2-0.5 microns and a second distribution peak in the particle size
distribution in the range of 1-6 microns.
2. The synthetic filament according to claim 1 wherein said
titanium dioxide particles consists essentially of those of
particle diameters 0.1-7 microns of which 15-60 percent by weight
consists of said coarse particles of particle diameter range 1-7
microns.
3. A synthetic filament according to claim 1 wherein the second of
said peaks falls within the range of 2-5 microns.
4. A synthetic filament according to claim 1 wherein said titanium
dioxide particles are contained dispersed in the melt-spun
synthetic filament in an amount of 0.1-0.7 percent by weight based
on said filament.
5. Textile products made from melt-spun titanium dioxide-containing
polyamide filaments containing dispersed through their structure in
an amount of 0.01-1 percent by weight, based on said filaments,
titanium dioxide particles consisting essentially of particles of
diameters 0.1-7 microns, of which 10-70 percent by weight consists
of coarse particles of diameters 0.8-7 microns, said titanium
dioxide particles having two distributuion peaks in their particle
size distribution, a first peak in the range of 0.2-0.5 microns and
a second peak in the range of 1-6 microns.
6. Textile products according to claim 5 wherein said coarse
particles occupy 15-60 percent by weight of the total amount of
said titanium dioxide particles, said titanium dioxide particles
being contained dispersed in said filaments in an amount of 0.1-0.7
percent based on said filaments.
7. Textile products according to claim 6 wherein said second peak
of the particle size distribution falls within the particle
diameter range of 2-5 microns.
Description
This invention relates to titanium dioxide-containing synthetic
filaments which, as compared with the conventional product, have
improved surface properties as a result of its content of titanium
dioxide of improved characteristics, textile products made
therefrom and a method of imparting said improved properties. More
particularly, the invention relates to synthetic filaments
containing titanium dioxide having improved characteristics in the
particle distribution and in which the surface properties have been
improved, which is characterized in that there are contained
dispersed in the melt-spun synthetic filaments, in an amount of
about 0.01-1 percent by weight, and preferably 0.1-0.7 percent by
weight, based on the weight of said filament, titanium dioxide
particles substantially having a particle diameter not greater than
7 microns, and generally about 0.1 -7 microns, of which particles
10-70 percent by weight, and preferably 15-60 percent by weight of
the said titanium dioxide, consists of coarse particles of particle
diameter 0.8-7 microns, and preferably 1-7 microns, it being
preferred that two peaks in the particle size distribution are
present, one each in the two ranges of (1) a particle diameter
range of the coarse particles, including those whose particle
diameter are preferably in the range 1-6 microns, and more
preferably 2-4 microns, and (2) a particle diameter range of
particles smaller said coarse particles, including those whose
particle diameters are preferably in the range 0.2-0.5 microns; to
the textile products made therefrom; and to a method of imparting
such improved properties.
A most important advantage of the improvement is that the
smoothness of the synthetic filaments is notably improved without
causing an undesirable luster effect or loss of brightness in
filaments. The term "smoothness" as used herein means easiness in
processing of these filaments into fabrics and knittings depending
upon the lower dynamic friction resulting when the filaments are
passed over guide surfaces at high speed. Hence, the drawbacks such
as filament break during its reeling, warping, weaving or knitting
and losses in the quality of the final textile product due to the
filaments being subjected to an excessively great variation in
tension are removed to a still greater extent than the conventional
titanium dioxide-containing synthetic filaments. In addition, there
are such advantages as that the easiness in the aforesaid
processing is enhanced still further and that there is not fear of
causing the loss of the brightness of color development in its dyed
products.
It has been a well-known practice to incorporate titanium dioxide
as a so-called "delustrant" in the synthetic textile fibers
produced by melt-spinning such fiber-forming synthetic polymers as
polyamides, polyesters and polyolefins.
In this case, the mean value of the particle size of the titanium
dioxide incorporated in the synthetic textile filaments is not
greater than 0.5 micron, and usually in the range of about 0.2-0.3
micron. The most important reason why its particle size is not
greater than 0.5 micron is that the delustring effect of titanium
dioxide is greatly influenced by the particle size of the titanium
dioxide. Namely, the covering power of titanium dioxide, the
criterion of its delustring effect, is greatest when its particle
diameter is about 0.3-0.4 micron and decreases as the particle size
becomes greater than this range. Since, therefore, the delustring
effect decreases when the larger size titanium dioxide particles
are employed and thus has proved to be undesirable from the
standpoint of its delustring effect which is the primary purpose
for using titanium dioxide, the larger size particles are not
employed usually.
On the other hand, it is known that filaments break and losses in
the quality of the end products are prevented during the operations
such as reeling, warping, weaving or knitting if there is an
increase of the content in the synthetic filament of the finely
divided particles of titanium dioxide of the aforesaid particle
size, as presently being actually used. In addition, an enhancement
of the easiness in processing can be expected. However, depending
upon the use to which the fiber is to be put, the use of titanium
dioxide in an amount in excess of its proper amount as a delustrant
causes an excessive loss of the brightness in the synthetic
filament and not only has the reverse effect of reducing its
merchandise value but also causes the loss of the brightness in
color development when it is dyed and further leads to undesirably
high losses in tensile properties. Hence, as a matter of course, a
restriction is imposed on the extent to which an increase can be
made in the content in the synthetic filament of the titanium
dioxide of which particle size is less than 0.5 micron in mean
particle diameter, and usually in the range of 0.2 -0.3 micron as
are used in practice, in an attempt to achieve adequate
improvements in such as the prevention of filament break and loss
in quality as well as enhancement of processability. Consequently,
the achievement of still further advancement in the aforesaid
improvement could not be hoped for.
With a view to overcoming the limitation imposed on the improvement
due to such a restriction as to the content of titanium dioxide in
the filament and as a result provide a titanium dioxide-containing
synthetic filament having the previously noted numerous improved
advantages wherein a proper degree of delustrings effect of the
brightness of the synthetic filament is manifested without the loss
of brightness to an undesirably excessive degree and hence in which
the smoothness of the filament is improved still further without
the necessity of increasing the content of the titanium dioxide
excessively, we investigated the relationship between the particle
size and its distribution of titanium dioxide and the surface
characteristics and brightness of filament. In consequence, we have
found, as hereinbefore noted, a new type of titanium dioxide by
which the aforesaid object can be achieved. Namely, we have found a
method wherein by the conjoint use of titanium dioxide of a
particle size greater than that customarily employed, i.e., coarse
particles having a particle diameter 0.8 -7 microns whose
delustring effect is small, with the conventional titanium dioxide
of a mean particle diameter of 0.2 -0.5 micron whose delustring
effect is great, it is possible to obtain fibers which would
effectively demonstrate the two properties of aforesaid smoothness
and brightness. BY this finding the coarse particle titanium
dioxide which had hitherto been regarded as being practically
worthless from the standpoint of its delustring effect is employed
from a new angle. Hence, this is a novel invention.
It is therefore the primary object of this invention to over come
the above-mentioned drawback or loss in brightness of filament
inevitably resulting from the content of titanium dioxide in the
conventional method by a method which could not have been expected
from the common knowledge of the art, and to provide a titanium
dioxide-containing synthetic filament and the textile products made
therefrom having improved filament surface characteristics and its
smoothness as compared with the conventional products.
Another object of the invention is to provide an improved process
for production of such filaments.
A further object is to provide titanium dioxide having a special
particle size distribution, which has not been used hitherto in
achieving such an improvement and which is especially suited for
utilization therefor.
Other objects and advantages of the invention will be apparent from
the following description.
The titanium dioxide-containing synthetic filament of this
invention contains dispersed throughout its structure in an amount
of 0.01-1 percent, and preferably 0.1-0.7 percent, by weight, based
on said filament, titanium dioxide having a particle size not
greater than 7 microns; 10 -70 percent by weight, and preferably
15-60 percent by weight, of the total titanium dioxide particles
contained in the said filament being coarse particles having a
particle diameter from 0.8 to 7 microns, and preferably in the
range of 1-7 microns. Because the filament has a rough surface, an
area of contact of it with a guide surface is reduced, and
consequently the effective yarn coefficient of dynamic friction is
reduced. Hence, the smoothness of a filament is improved because of
the lower dynamic friction.
Further, it is particularly preferred that titanium dioxide should
have two peaks in its particle size distribution, each in the
particle diameter range of the aforesaid coarse particles and the
other that of particles smaller than said coarse particles.
Titanium dioxide of this type has not per se been proposed
heretofore nor has it been used as a delustrant.
As the titanium dioxide of the hereinabove described type, a
preferred and typical one employed in this invention is one wherein
one of said two peaks in particle size distribution falls within
the particle diameter range of 0.2-0.5 micron and the other peaks
falls within the particle diameter range of 1-6 microns.
As example of this type of titanium dioxide will be more fully
described with reference to the accompanying drawing, in which:
FIG. 1 is a rough drawing illustrating one example of the particle
size distribution of the new type titanium dioxide suitable for use
in this invention.
FIG. 2 is a rough drawing similar to that of FIG. 1 of a titanium
dioxide having conventional particle size distribution, such as has
been employed heretofore as a delustrant.
FIG. 3 is a similar rough drawing illustrating one example of a
titanium dioxide having a particle size as was not utilized
heretofore as a delustrant.
FIGS. 4, 5 and 6 are graphs showing the relationships between the
proportion of coarse particles contained in titanium dioxide
containing coarse particles of 0.8-7 micron in amounts as
substantially employed in the invention and the coefficient of
dynamic friction of yarn, brightness of filaments and abrasiveness
of metal by the filament containing the titanium dioxide.
The titanium dioxide employed in this invention, as illustrated in
FIG. 1, has two peaks in particle size distribution, peak A within
the particle diameter range of the coarse particles and peak B
within that of the particles smaller in diameter than the coarse
particles. In FIG. 1 is illustrated an instance where the peak A
falls within the range of the particles having particle diameters
of 0.2-0.5 micron and peak B falls within the range of the
particles having particle diameters of 1-6 microns.
FIG. 2 illustrates an example of a titanium dioxide such as has
been employed heretofore as a delustrant which has a peak A' within
a range of particle diameters of 0.2-0.5 micron, while FIG. 3 shows
an example of a titanium dioxide of coarse particles which was
heretofore regarded as being undesirable for use as a delustrant in
the point of its delustring effect and hence has not employed. Its
particle size distribution peak B' falls within a range of the
particle diameter of 1-6 microns.
In general, the particle size distribution of titanium dioxide is
principally influenced and determined by a hydrolytic step during
its preparation, and therefore titanium dioxide with a particle
size distribution having essentially a single peak is usually
produced in accordance with the generally known crystal particle
formation phenomenon, while there is a difference in the position
of the peak, as shown in FIGS. 2 and 3.
The titanium dioxide such as illustrated in FIGS. 2 and 3 are not
capable of achieving the objects of this invention when they are
each used alone.
Needless to say, the type of titanium dioxide such as shown in FIG.
1 is generally not available commercially. However, it can be
obtained by blending in arbitrary proportion the usual types of
titanium dioxide such as shown, for example, in FIGS. 2 and 3; or
by crushing a part of a titanium dioxide having the particle size
distribution shown in FIG. 3 or one whose peak B' is still larger
and thereafter blending the so crushed particles with the remaining
large particles in arbitrary proportion, or by changing the
conditions for the crystal particle formation during the
preparation of the particles at an interim point of the formation
process; but the method of just blending together the two types,
i.e., those consisting of respectively coarse and finely divided
particles, is the easiest way of obtaining the titanium dioxide
employed in this invention, and is to be recommended. Hence, the
titanium dioxide to be employed in this invention may be prepared
by any means so long as aforesaid requisites are satisfied. In
obtaining the desired titanium dioxide by blending in an arbitrary
proportion two or more classes of the single peak-type titanium
dioxides, needless to say, the mixing may be carried out not only
in just the dried state of these titanium dioxide but may also be
carried out in their slurry state. From the operational standpoint
it is easier to carry out the mixing in the slurry state.
The most desirable type of titanium dioxide to be employed in this
invention is such as is shown in FIG. 1, but the results intended
by this invention cannot be expected by the use of the usually
employed titanium dioxide having a mean particle diameter of
0.2-0.3 micron, and on the order of about 0.5 micron even in the
case of the largest particles, and in which the content of the
coarse particle titanium dioxide of above 0.8 micron is less than
10 percent. On the other hand, when the particle diameter of the
titanium dioxide exceeds 7 microns, it cannot be employed, because
there is a tendency to the occurrence of break of the synthetic
filament containing such a titanium dioxide as well as a pronounced
decline in easiness of drawing during filament-making process.
FIG. 4 shows the relationship between the changes in the proportion
of coarse-particle titanium dioxide having particle diameter of
0l8-7 microns to the total content of titanium dioxide and the
changes in the coefficient of dynamic friction when a 30 denier-6
filament nylon yarn was passed over at 100 meters per minute while
in contact with a metal. It is apparent from this figure that the
coefficient of dynamic friction decreases remarkably as the
proportion of the coarse-particle titanium dioxide becomes about 10
percent, thus resulting in an improvement in the yarn's smoothness
as demonstrated by its slidability over the metal and consequently
in an improvement of the processability of the yarn. On the other
hand, the relationship between the brightness of the yarn and the
proportion of the coarse-particle titanium dioxide in this case is
as shown in FIG. 5. It is seen that as the proportion of the coarse
particles becomes greater, the brightness tends to become excessive
and the delustring effect as intended by the addition of titanium
dioxide decreases to an excessive degree. On the other hand, as
shown in FIG. 6, if the proportion of the coarse particle titanium
dioxide is increased, it is seen that the abrasiveness of a metal
by the yarn when the yarn is passed over while in contact with the
metal tends to increase, which is not desirable. That the filament
of this invention, which contains the coarse-particle titanium
dioxide, has the unique properties as shown in FIGS. 4-6 is, as
apparent from FIG. 7, due to the fact that its surface has been
roughened by the coarse-particle titanium dioxide. Thus, when the
delustring effect and the metal abrasiveness by yarn are
considered, the amount to be occupied by the coarse-particle
titanium dioxide having a particle diameter of 0.8-7 microns in
total content in the filament of the titanium dioxide having a
particle diameter not greater than 7 microns should properly be
10-70 percent by weight, and preferably 15-60 percent by weight, of
the total content in the filament of titanium dioxide.
In incorporating the specific titanium dioxide in the fiber-forming
synthetic polymer in this invention, titanium dioxide particles of
particle size and particle size distribution as will satisfy the
previously described specific conditions are added to the reaction
system prior to the completion of the polymerization reaction,
preferably during that period of the intermediate stage of the
polymerization reaction when a low polymer is being principally
formed in the reaction system or prior to this period, for example,
before beginning of the polymerization, at the beginning or the
initial to the intermediate stages of the polymerization reaction,
the addition being made in a slurry state using, say, water and/or
a monomer, and in an amount such that the said titanium dioxide
particles are contained in the resulting polymer in a range of
0.01-1 percent by weight. After completion of the polymerization
reaction, the resulting fiber-forming synthetic polymer is made
into filaments by melt-spinning.
Needless to say, it is desired that the titanium dioxide is
contained in the filament in a homogeneously dispersed state. For
example, since the coarse particle component corresponding to the
peak B shown in FIG. 1 settles to the bottom is a very short period
of time, great care must be exercised to ensure that the titanium
dioxide is well dispersed in the titanium dioxide slurry as well as
in handling the prepared slurry.
For improving the dispersibility, Good results are had by the use
of a suitable inorganic or organic dispersing agent. As such
dispersing agents, included are the inorganic dispersing agents
such, for example, as sodium pyrophosphate, sodium polyphosphate
and sodium polymetaphosphate, and the organic dispersing agents
such, for example, as the condensation products of polyoxyethylene
glycol and an alkyl phenol of the following formula:
wherein n is an integer from 3 to 16 and x is an integer from 20 to
40.
The polymers to which this invention can be applied are the
fiber-forming synthetic polymers which include the copolymers and
blended polymers as well, and include the polyamide type polymers,
the polyester type polymers and the polyolefin type polymers.
The following nonlimitative examples further illustrate the present
invention. The measurement values for coefficient of dynamic
friction, brightness, abrasiveness, unwinding tension of pirn,
tensile strength, fluctuation of yarn tension during warping and
yarn break during knitting of tricot, as referred to in the
examples as well as the drawings, were determined in the following
manner.
Brightness
0.5 Gram of the sample is placed in a 8:2 phenol-methanol mixture
and dissolved therein by heating at 50.degree. C. This solution is
then measured for its transmittance using a photoelectric
photometer (manufactured by Hitachi Ltd., Japan; Model FPW-4). The
transmittance indicated was adopted as the measure of the
brightness of the yarn.
It is undesirable for this brightness to be too small or too great.
The optimum value will depend on the use to which the yarn is to be
put, but when a semidull yarn is desired with an addition of the
titanium dioxide in an amount of 0.3-0.5 percent, a value on the
order of 20-65 percent is most suitable.
Abrasiveness
The abrasiveness is a value obtained by passing over the synthetic
fiber in contact with a copper wire (guide) under the following
conditions:
Speed of yarn travel 200 m./min. Time of travel 40 min. Tension
guide front 7.5 grams guide rear 25 grams
The amount of wear of the copper wire is obtained by the depth of
focus of a microscope and this is indicated in microns (.mu.). This
abrasiveness should be less than 100 microns, and preferably less
than about 70 microns, the lower, the better.
Coefficient of Dynamic Friction
The coefficient of dynamic friction is obtained by passing over a
synthetic yarn in contact with a metallic rod under the following
conditions, measuring the yarn tension at the front and rear sides
of the metallic rod and substitution of the so obtained values in
Ammonton's expression to obtain the coefficient of dynamic friction
(.mu.d).
Speed of yarn 300 m./min. Original tension (T.sub.o) 5 grams Angle
of contact with the metallic rod (.theta.) .pi. radian
wherein T.sub.1 is the secondary side tension. This coefficient is
suitably not greater than 0.3, and particularly not greater than
about 0.25.
Unwinding Tension of Pirn
A synthetic yarn forming a pirn is unwound from said pirn at a
linear speed of 300 meters per minute and the yarn tension between
the topmost part of the pirn and a guide disposed at a distance 30
centimeters therefrom perpendicularly of said pirn is measured.
Tensile Strength
A Schopper's fiber tensile tester is used and pulling a 50-cm.
length yarn at a speed of 50 centimeters per minute, the maximum
strength (G) is measured.
Separately, yarn 900 meters in length is dried in an electrically
heated constant temperature camber of 105.+-.2.degree. C. until it
is absolutely dried, after which it is weighed and its denier (D)
is obtained. The tensile strength is calculated by the following
expression:
Tensile strength = G/D
Fluctuation in Yarn Tension During Warping
The tension of the yarns immediately prior to their being wound up
on the beam during warping is measured under the following
conditions and the standard deviation is calculated.
Yarn speed 300 m./min. Number of yarns 620 Tension compensator
Washer type
Yarn Break During Knitting of Tricot
The number of yarn breaks occurring during the knitting of half
tricot under the following conditions are determined.
Knit density 58 courses/inch Number of rotations 800 r.p.m. Knit
width 200 inches
EXAMPLE 1
Six parts by weight of titanium dioxide of the type shown in FIG.
2, which is usually used as a delustrant, (except that the mean
particle diameter was 0.25 micron) and 4 parts by weight of a
coarse-particle titanium dioxide of the type shown in FIG. 3
(except that the peak position was at 2 microns) were added to 90
parts by weight of water, after which the titanium dioxide was
dispersed with stirring, thereby obtaining a 10 percent aqueous
slurry of titanium dioxide. The so obtained aqueous slurry of
titanium dioxide was added along with a small amount of a titanium
dioxide dispersing agent to an aqueous 85 percent
epsilon-caprolactam solution in an amount such that the content of
titanium dioxide would become 0.3 percent by weight, after which
the mixture was stirred to prepare a compounded lactam aqueous
solution for polymerization use. The compounded lactam aqueous
solution was then melt polymerized in customary manner and the
intended polyamide chips incorporated with titanium dioxide was
obtained. The so obtained polyamide chips were used and a 30
denier-6 filament yarn was obtained by the usual melt-spinning
method. THe properties of the so obtained yarn are shown in table
I, below. By way of comparison, also shown in table I are the
instances of a yarn obtained in exactly the same manner except that
it contained 0.3 percent by weight of the heretofore used titanium
dioxide of the type shown in FIG. 2 (comparison 1), a yarn obtained
in exactly the same manner except that it contained 0.3 percent by
weight of only the titanium dioxide of coarse particles (comparison
2) and a yarn obtained in exactly manner but containing no titanium
dioxide at all (Control). ##SPC1##
As demonstrated by the results shown in table I, above, when the
warping and knitting of a tricot were carried out using the yarn in
example 1, the value of the yarn tension and its variation were
small, and improvements form the operational standpoint and the
quality of the product were achieved.
EXAMPLES 2-7
Titanium dioxide usually used as a delustrant of the type shown in
FIG. 2 (mean particle diameter 0.25 micron) and coarse-particle
titanium dioxide of the type shown in FIG. 3 were mixed in varied
proportions, and to these mixture water was added to obtain various
slurries of titanium dioxide. These slurries were used and, as in
example 1, 30 denier-6 filament polyamide yarns containing the
titanium dioxide having two peaks in this particle size
distribution were obtained. The properties of these yarns are shown
in table II, below. ##SPC2##
It can be seen from the results shown in table II, above, that the
titanium dioxide-containing filaments of this invention exhibit
excellent qualities and that the position of the peak (B) of the
coarse particle in the titanium dioxide particle size distribution
and the content of the coarse particles (0.8-7 .mu.) in the
filaments can be modified and adjusted.
EXAMPLES 8-11
In table III, below, are shown the results obtained when the
experiment was carried out as in example 1, except that the
titanium dioxides used were those whose particle diameter was 0.1-7
microns and of which 40 percent by weight of total content of
titanium dioxide in the filament consisted of particles having a
diameter of 0.8-7 microns, but the titanium dioxide particle size
distribution peak (B) was varied. By way of comparison, also shown
are instances where said peak was at below 1 micron and at above 7
microns (comparisons 3 and 4). ##SPC3##
As demonstrated by the results shown in table III, it can be seen
that even though the proportion of the coarse-particle titanium
dioxide to its total content in the filament is the same, the
properties of the filament will vary depending upon the position of
the peak (B) in the titanium dioxide particle size distribution,
i.e., the particle size and its distribution of the coarse-particle
titanium dioxide. When the position of the peak (B) of the coarse
particle in the titanium dioxide particle size distribution is at
0.5 microns, the brightness and abrasiveness are satisfactory, but
the results anticipated for the coefficient dynamic friction and
processability are not obtained. On the other hand, when the
position of the peak (B) of the coarse particle in the titanium
dioxide particle size distribution exceeds the upper limit
prescribed by the invention and is at 8 microns, good results can
be obtained with respect to the coefficient of dynamic friction and
variation in yarn tension during warping, but the yarn break during
warping and knitting of tricot and abrasiveness are great, and
moreover decline in tensile strength takes place, and hence is not
desirable from the standpoint of the quality of the product.
EXAMPLE 12
A titanium dioxide slurry was obtained by adding to 90 parts of
water 5 parts of titanium dioxide of the type shown in FIG. 2 (mean
particle diameter 0.25 micron) which is usually used as a
delustrant and 5 parts of coarse-particle titanium oxide of the
type shown in FIG. 3 (mean particle diameter 1 micron). The so
obtained slurry was used and, as in example 1, polyamide chips
containing 0.3 percent of titanium dioxide having two peaks in the
particle size distribution was obtained. A 15 denier-1 filament
yarn was obtained using the foregoing polyamide chips. When this
yarn was used and women's hose were knit therefrom, the variation
in the yarn tension was small and its was possible to make hose of
uniform length. Again, the meshes and loops of the hose were
uniform.
On the other hand, hose which were knit from yarn produced by the
same manufacturing process as this yarn and containing titanium
dioxide of the type usually used as a delustrant in an amount equal
to that of this yarn were not of uniform dimension and the size of
the loops was also irregular.
EXAMPLE 13
A 30 denier-6 filament polyamide yarn was obtained, as in example
1, using titanium dioxide which, being made up of particles of
diameter not greater than 7 microns and containing coarse-particle
titanium dioxide in a proportion of 30 percent by weight of the
total titanium dioxide, but had only one peak in the titanium
dioxide particle size distribution. The properties of this yarn are
shown in table IV. Further, by way of comparison, the results
obtained in the case of a yarn in which was used titanium dioxide
of the type shown in FIG. 1 whose proportion of coarse-particle
titanium dioxide of 0.8-7 microns to its total content in the
filament was 30 percent and in which two peaks in the titanium
dioxide particle size distribution were present (comparison 5) and
the results of comparison 1 previously shown in table I are also
shown. In all cases the content in the filament of the titanium
dioxide was 0.3 percent. As apparent form the results shown in
table IV, while the effects of this invention can be expected even
thought there is only one peak in particle size distribution so
long as coarse-particle titanium dioxide of 0.8-7 microns is
contained, the effects are less than when there are two peaks.
##SPC4##
* * * * *