US3439084A - Thick and thin yarn and process for the preparation thereof - Google Patents

Description

Sheet of 2 uMlcHl ONO ET AL THICK AND THI ARN AND PROCESS FOR THE PREPARATION THEREOF TER April 15, 1969 Med Aug 4 1966 April 15, 1969 TERUM|CH| ONO ET AL 3,439,084

THICK AND THIN YARN AND PROCESS FOR THE PREPARATION THEREOF filed Aug. 4, 1966 Sheet 2 of 2 g 5 HQ 6 (NYLON 66) (NYLON e) 20 2C} z o IO g3:

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x X E 3 3 X United States Patent US. Cl. 264-467 4 Claims ABSTRACT OF THE DISCLOSURE A process for the preparation of thick and thin yarn characterized by the following properties:

(a) the ratio of the cross sectional area of the basic drawn filament parts to that of enlarged parts is 1:2-1215;

(b) the enlarged parts are present with the frequency of at least 1 per mm. along the yarn length; and

(c) the modified configuration of the cross section is substantially continuous along the length of the yarn,

such process comprising extruding a molten filamentforming synthetic polymer, e.g. linear polyamide through a spinneret under the condition to exert such shear stress that melt fracture occurs at the frequency of 10 to 10 order per second and under conditions of non-quenching such that there will be no substantial solidification of the as-spun yarn until the point at which the drafting of the yarn starts.

This invention relates to novel and useful thick and thin yarn of melt-spinnable synthetic polymer, inter alia, synthetic linear polyamide, and a process for the preparation thereof.

More particularly, the invention relates to thick and thin yarn of melt-spinnable synthetic polymer having at intervals enlarged parts of greater cross-sectional area than that of the basic drawn filament parts continuously along the yarn length, characterized in that (a) the ratio of the cross-sectional area of the basic drawn filament parts P to that of the enlarged parts Q is 1:21:15,

(b) the said enlarged parts are present with the frequency of at least one per 30 mm. along the yarn length, and

(c) the modified configuration of the cross-sectional area is substantially continuous along the length of the yarn.

Furthermore, the invention relates to a process for the preparation of such yarn which comprises extruding molten filament-forming synthetic polymer through a spinneret under a shear stress condition to cause formation of melt fracture and non-quenching condition, and subsequently drawing the as-spun filaments. 6

Filaments having continuously along its length enlarged parts of greater cross-sectional area than that of the basic drawn filament parts at intervals are well known as thick and thin yarn or nodular filaments. Such filaments can be made into fabrics for textile and other uses with a pleasing hand and with attractive surface variations in appearance.

Also, modified cross-sectional filaments, for example, those having flat or triangular cross-sections are known 3,439,084 Patented Apr. 15, 1969 in relation with the technique for varying hand and luster, etc., of fibers.

And, such thick and thin yarn has been held valuable as the means to impart the properties resembling those of natural fibers having slub such as linen or dupionic silk to synthetic fibers. Whereas, it is again well known that the attempt to impart filament strength of any practical value to the yarn results in the loss of most or considerable pars of the properties desirable for thick and thin yarn, as such an attempt causes excessive reduction in the cross-sectional area of the enlarged part and/0r extension in the basic drawn filament parts resulting in the presence of the enlarged parts along the yarn length at an objectionably low frequency. As a means for overcoming such deficiency, use of cracking agent was pro posed. However such has also deficiencies incidental thereto, if it is useful to eliminate the first deficiency, such as the complicated and skill-requiring operation of crack ing step, need of an additional step for removing the cracking agent and the influence of cracking agent on fiber quality which is not always negligible.

On the other hand, modified cross-sectional fibers are excellent particularly in luster property, and can be imparted desirable degree of stiffness. However, when they are made into textile, continuous, long linear lustrous parts, so-called bright lines, appear in the textile to impair the appearance of the textile as a whole.

Accordingly if thick and thin yarn can be prepared without using cracking agent and with easy means, and furthermore if the resulting yarn possesses concurrently the desirable properties for thick and thin yarn as well as the luster property and preferred degree of stiffness of modified cross-sectional filaments but with no possibility of producing the objectionable bright lines in use, such will be highly useful in the field of the concerned art.

After an extensive research in the purpose of providing such novel and useful yarn, we found that the filaments meeting the aforesaid three requirements (a), (b) and (c) may be provided. Filaments simultaneously meeting all of the requisites have never been proposed before. Expressing in another Way, by the invention novel thick and thin yarn of unique form is provided, which possesses all of the advantageous properties characteristic to thick and thin yarn and has its cross-sectional area along the yarn length substantially continuously modified, normally the cross-sectional modification continuously varying at considerably short intervals and the modification being present continuously along the yarn length.

This yarn is again characterized in that the areas of its enlarged parts maintain their configuration during the subsequent drawing step and are substantially not reduced. It is furthermore characterized in that its modified cross-sectional shape continuously varies along the yarn length at considerably short intervals. In other words, in the yarn of the invention the phase of the modified configuration of its cross-section varies at short in- 0 tervals, viz, the cross-section does not take same phase at a long interval along the length -of the yarn, as shown in FIG. 4. Most likely this features contributes to the yarn property not to form the objectionable bright line in textile like conventional modified cross-sectional yarn, while the yarn does possess an excellent luster property.

Accordingly, the object of the present invention is in the provision of novel and useful thick and thin yarn having only the preferred properties of modified crosssectional yarn as well as the advantageous properties of conventional thick and thin yarn.

Another object of the invention is in the provision of a process for the preparation of such unique yarn with industrial advantage and high efficiency without using cracking agent or special equipments.

Many other objects and advantages of the invention will become more apparent from reading the following descriptions.

It was found that when the yarn of the invention is made into textile such as gauze, satin or taffeta and dyed, the enlarged parts or nodes are dyed deep due to the difference between the cross-sectional area thereof and that of the basic drawn filament parts, and/or due to the diiference in dyeability between them. And consequently pepper-and-salt patterned textile having luster, rough hand and desirable degree of stiffness as well as attractive surface properties not obtainable with conventional thick and thin yarn, can be prepared.

To wit, the thick and thin yarn of the invention concurrently possesses manifold properties seen in no prior art because of its unique, characteristic configuration and opens a new field of development in the art concerning thick and thin yarn.

Hereinbelow the thick and thin yarn of the invention will be explained in still fuller detail with reference to the drawings.

FIG. 1 is an enlarged view for explanation showing a side view of a portion of undrawn yarn to serve as the material for the thick and thin yarn of the invention.

FIG. 2 is a similarly enlarged view showing a side view of a portion of the thick and thin yarn of the invention.

FIG. 3 and 3' are similarly enlarged views showing two examples of the cross-sectional shapes of the thick and thin yarn of the invention.

And, FIG. 4 is a similarly enlarged view for explaining the other characteristics of the yarn of the invention.

As can be understood upon comparing FIG. 1 with FIG. 2, in the thick and thin yarn of the invention the enlarged parts are substantially not reduced during the drawing step. And, as shown in the one embodiment shown in FIG. 4, the ratio of cross-sectional area of the basic drawn filament parts P to that of the enlarged parts Q is within the range of 1:21:15. Again the enlarged parts appear along the length of the yarn at a frequency of at least one per 30 mm. Particularly, it is preferred that PzQ be 1:4-1z10, and the frequency be at least 2 Furthermore, unlike the conventional product, in the thick and thin yarn of the invention its cross-sectional configuration is modified as shown in FIGS. 3, 3' and 4, and, although not shown in the drawings, the cross-section takes substantially continuous irregular shape along the length of the yarn. FIG. 3 is a cross-sectional view of the drawn thick and thin yarns of the invention cut at a certain portion, both the enlarged parts and basic drawn filament parts appearing therein. FIG. 3' is the crosssection of the yarn cut at an optional point very close to the part shown in FIG. 3, similarly showing the two different types of parts. Such cross-sectional modification similarly appears when the yarn is cut at any point along its length although somewhat varied in the modified shape, and never is completely lost. In the invention, such a state is referred to when the modified crosssectional configuration is said to be substantially continuous along the length of the yarn.

The thick and thin yarn of the invention is furthermore characterized in that the said modified configuration continuously varies along the length of the yarn, at the shortest possible intervals. An example of such short interval is shown in FIG. 4. In the invention the variation takes place at least once between the adjacent enlarged parts. In FIG. 4, cross-sections taken at very short intervals are shown, indicating that in the modified form, the phases of its parts such as of straight line or downwardly curved line vary at short intervals. Furthermore, the

variation is not independently present for each section, but is substantially continuous as afore-described.

Such thick and thin yarn meeting all of the requirements (a), (b) and (c) is entirely novel.

For example, undrawn filament somewhat resembling the subject yarn may be prepared by using a spinneret having orifices of modified configuration and varying the discharge amount of the melt passing therethrough, but when the filament is drawn, the product no more meets the requirements (a), (b) and (c) concurrently. Particularly it is by no means possible to produce thick and thin yarn in which the modified cross-sectional configuration continuously varies at the shortest possible intervals along the length of the yarn.

The novel and useful thick and thin yarn of the invention is prepared utilizing a unique phenomenon ob served in extrusion of polymer other than filament-forming type which is never expected to take place in the meltspinning of filament-forming polymer. To wit, for example polytetrafluoroethylene being a polymer known for its lack of fiber-forming ability by melt-spinning, when it is melted, for example, at 360 C., it takes a state resembling normal molten state although not melt-spinnable and comes to have a viscosity extremely high than that of the melt of melt-spinnable, fiber-forming polymer. When the polymer in that state is forced through a capillary, mass of irregular contour entirely different from the contour of the extruding end of the capillary is formed. This phenomenon is called melt fracture, and of course such a mass of the described type of polymer cannot be drafted or made into thick and thin yarn.

The process of the subject invention utilizes this phenomenon for melt-spinnable, fiber-forming polymer under specific conditions, to produce the afore-described unique thick and thin yarn with good reproducibility. Accordingly, with the subject process the novel and useful yarn can be prepared without any cumbersome step such as varying the discharge amount of the melt or use of a cracking agent or a spinneret of modified orifices. Such was not expected before in the art of thick and thin yarn production. Conventionally melt-spinning of fiber-forming polymer is performed invariably under such extruding conditions as will smooth the fiow of molten polymer.

In the present invention, the melt-spinning is performed under the shear stress conditions to produce melt fracture and nonquenching condition.

It is quite surprising that by thus melt-spinning fiberforming polymer under the conditions entirely opposite to the conventional technical concept, such unique thick and thin yarn as above described can be extruded with stability to provide novel and useful yarn.

The present invention can be widely applicable to meltspinnable synthetic polymer in general, while it may be understood that linear polyamide is the most preferable. In the invention as linear polyamide, polycaprolactam (nylon-6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,10), poly-waminoheptanoic acid (nylon-7), poly-w-aminononanoic acid (nylon-9), polyundecanamide (nylon-11), polylauriclactam (nylon-l2), polyamide from paraxylilenediamine and dodecandioic copolyamides composed of two or more of the foregoing polyamides, modified polyamides grafted or block-polymerized with other monomer to the extent not essentially changing the properties of linear polyamide, and polyamide blends of two or more of the foregoing polyamides or of the polyamide with other meltable polymer in an amount within the range not essentially changing the properties of linear polyamide, are contemplated.

Among those linear polyamides, particularly the invention is applied to polycaprolactam and polyhexamethylene adipamide with advantage.

It is of course permissible that above-named polymers contain conventional additives such as stabilizer for light, stabilizer for heat, delusterant, and pigments.

The shear stress (7 referred to in the present specification and claims is the value determined by the method disclosed in E. B. Bagley, I. Appl. Phys. 28, 624 (57), and expressed by the Equation 1 below.

wherein P is the discharge pressure, R is the radius of holes in the spinneret, L is the length of the holes and n is the tube length modification coefficient.

In the process of the invention, the aforesaid meltspinnable synthetic polymer is melted, and extruded under such shear stress condition as will produce melt fracture and non-quenching condition. Specific value of the shear stress to be employed widely varies depending on the type of polymer and the degree of polymerization thereof, while generally the value in the order of at least is preferred. And, it is also newly discovered that the shear stress to produce melt fracture has upper limit corresponding to each specific type and degree of polymerization of the polymer, and that when the shear stress exceeds the upper limit, the production of the useful melt fracture tends to cease. The upper limit can be determined for each specific polymer empirically with case.

For the sake of explanation, in case polyhexamethylene adipamide is used as the synthetic linear polyamide, it is preferable to extrude the melt of the said polyamide under the shear stress defined by the Formula 2 below,

7.5 m msn an": (2)

wherein 'T stands for shear stress (dyne/cm?) and n, stands for relative viscosity measured in 25 C., 98% sulfuric acid.

wherein 1,, stands for shear stress (dyne/cm. and 1 stands for relative viscosity measured in 25 C. 98% sulfuric acid IO'L'I/ LBs Z 107 and also under non-quenching condition. By the same reasons described as to the case of polyhexamethylene adipamide, the preferred range of 1 of polycaprolactam is 2.09.0.

FIGS. 5 and 6 respectively show the operable area as to polyhexamethylene adipamide and polycaprolactam. In the same figures, the axis of ordinates show the shear stress expressed in dyne/cm? and the axis of abscissae is to express relative viscosity (p of the synthetic linear polyamide. The areas contained by solid lines in the said figures show the melt-spinnable areas of the thick and thin yarn of the invention.

In the present invention, by extruding the melt-spinnable polymer under the specific shear stress extrusion condition as above described, its melt fracture is produced at an extremely high order of frequency such as 10 l 0 times per second. Therefore the shear stress condition as will cause production of melt fracture referred to in the invention may be expressed in another way as such extrusion condition to produce melt fracture at a very high frequency in the order of 10 -10 per second. The formation of melt fracture at such high order of frequency in this invention is again entirely unexpected for the conventional concepts in the field of melt-spinning techniques of melt spinnable fiber-forming polymer.

Furthermore, in order to obtain the thick and thin yarn meeting the aforesaid requirements (a) through (c) in accordance with this invention, adoption of nonquenching condition in combination with the above shear stress condition to form melt fracture is important. The as-spun filaments must not be quenched to bring about substantially instantaneous solidification thereof, while the greater parts of the extruded form can be deformed with relative ease. The as-spun filaments travel for a short distance from the discharge end of the spinneret, and thereafter are drafted by the tension exerted by winding roll, and thus the molten filaments are elongated. In accordance with the process of the invention, the asspun filaments are prevented from exposure to rapidly cooling condition until they reach the point which is located below the spinneret and at which the drafting of the molten filaments starts, so that the substantial solidification of the filaments takes place at the lower part of the stream from the said point. The non-quenchin g condition referred to in this invention may be said to be such a condition as will not cause substantial solidification of as-spun yarn until the point at which the drafting of the yarn starts. For instance, conventionally practiced cooling by means of cooling chimney, or so-called slow cooling with moderately heated medium may be adopted. Accordingly, conditions and apparatus employed for normal melt-spinning of fiber-forming polymer may be utilized.

The position at which the substantial solidification of the molten extrudate takes place varies depending on such factors as discharge amount of the polymer melt, rate of winding, temperature and relative viscosity of the melt extrudate, and the denier of the object fiber. Whereas, it is sufficient to employ normal melt-spinning conditions under which the molten yarn is not deprived of the heat of fusion excessively before its substantial drafting starts, and the position can be empirically selected with ease in accordance with the above-listed conditions.

According to the process of the invention, the yarn is further subjected to drawing in the accepted manner to form molecularly oriented yarn of excellent physical properties. Normally the drawing is performed within the temperature range from room temperature to below melting point of the polymer employed. Normally adopted draw ratio ranges 1.23.5 times, preferably in the vicinity of 3 times given at the lowest permissible temperature.

The thick and thin yarn of the invention with the combined unique properties has utility as still better product in all conventional usages for known thick and thin yarns and modified cross-sectional yarns, and furthermore can provide fabrics of novel feeling in the forms such as staple fiber, crimped yarn and bulky yarn.

Now some of the embodiments of the subject invention will be explained with working examples.

Example 1 Nylon-6 having relative viscosity in a sulfuric acid of 3.4 was discharged under the following conditions, viz, the temperature of 280 C. and the cylindrical spinneret holes of 0.2 mm. in diameter and 0.2 mm. and 0.6 mm. in length. Also the discharge amount was varied from 2 t0 4, 6, 8, 10, 12, 14, 16 and 18 g./min. to produce as the consequence discharge conditions of varied shear stress. The polymer spun under the discharge conditions shown in Table 1 below was taken up at the rate of 60 m./min. for 1 g./min. of discharge amount to produce undrawn filaments which were subsequently drawn by 3.0 times to form thick and thin yarn having modified cross-section as shown in FIG. 3 continuously along its length. The number of nodes in the resultant, drawn thick and thin yarn was counted with the results as shown in Table 1. From the data obtained, it can be understood that in case nylon- 6 having a relative viscosity in sulfuric acid of 3.4 is used, the shear stress (the value obtained by Equation 1) of 5 10 2 l0 (dyne/cm?) is necessary and sufficient as TABLE 1 Drawn thick and thin yarn Discharge condition Discharge Shear stress Number of Number of amount (dyne/cm?) PzQ, 1 nodes per nodes per (g./min.) 30 mm. 100 mm.

2 (control) 3. 4X10 1:1 0 4 5. 0X10 1:3.7 5 16 6.9)( 1:7.5 4 13 7. 8X10 1:12. 8 4 11 9. 3X10 1:12. 4 5 14 1.1)(10 1:10.1 3 8 1. 2X10 1:8. 3 2 6 1. 7x10 1:5. 0 1 4 2. 2X10 1:1 0 0 Example 2 Nylon-6 having a relative viscosity of a sulfuric acid of 2.7 was discharged under the fOllOWing conditions, viz, the temperature of 255 C. and the cylindrical spinneret holes of 0.2 mm. in diameter and 0.2 mm. and 0.6 mm. in length. The discharge amount was varied from 2 to 4, 6, 8, 10, 12 and 14 g./min. to produce as the consequence discharge conditions of varied shear stress. The polymer spun under the discharge conditions was taken up at a rate of 60 m./ min. for 1 g./min. of the discharge amount under slow-cooling condition to produce undrawn filaments which were subsequently drawn by 3.0 times to be made into drawn yarn as shown in FIG. 4. The number of nodes in the resultant drawn yarn was counted with the results as shown in Table 2. From the data obtained, it can be understood that in case nylon-6 having a relative viscosity in sulfuric acid of 2.7 is used, the shear stress (the value obtained by Equation 1) of 8 10 2 l0 (dyne/ cm?) is necessary and sufficient as the discharge condition for producing the thick and thin yarn.

TABLE 2 Discharge condition Drawn thick and thin yarn Nylon-6,6 having a relative viscosity in sulfuric acid of 3.1 was discharged under the following conditions, viz, the temperature of 290 C. and the cylindrical spinneret holes of 0.2 mm. in diameter and 0.4 mm. and 0.8 mm. in length. The shear stress was varied as in Table 3 below by varying the rate of discharge. The polymer spun under the discharge conditions was withdrawn at a rate of 60 m./min., for 1 g./min. of the discharge amount under slow-cooling condition to produce undrawn filaments which were subsequently drawn by 3.0 times to be made into drawn yarn resembling that shown in FIG. 4. The number of nodes in the resultant drawn yarn was counted with the results shown in Table 3. Thus it can be understood that the selection of the shear stress within the range shown in the Formula 2 is a necessary and sufiicient condition for producing melt fracture with stability and advantage.

TAB LE 3 Thick and thin yarn (drawn yarn) Discharge condition shear stress Number of Number of (dyne/cmfl) PzQ nodes per nodes per 30 mm. mm.

3.98X10 (control) 1:1 0 0 5.40Xl0 1:3. 6 1 3 685x10 1:6.3 4 12 8.00 10 1:12. 4 7 20 912x10 1:10.9 7 19 1.20 (l0 1:7. 8 4 10 1.55 10 (control) 1:1 0 0 Example 4 Nylon-6,6 having a relative viscosity in sulfuric acid of 2.8 was discharged under the following conditions, viz, the temperature of 275 C. and the cylindrical spinneret holes of 0.2 mm. in diameter and 0.2 mm. and 0.4 mm. in length. The shear stress was varied as in Table 4 by varying the rate of discharge. The polymer spun under such discharge conditions was taken up at a rate of 60 m./min. for 1 g./min. of the discharge amount under slow-cooling condition to produce undrawn filamerits, which were subsequently drawn by 2.9 times to be made into a drawn yarn resembling that shown in FIG. 4. The number of nodes in the resultant yarn Was counted with the results shown in Table 4 below. Whereby it can be understood that the selection of the shear stress within the range shown in Equation 1 is a necessary and sufficient condition for producing melt fracture with stability and advantage.

TABLE 4 Thick and thin yarn ((drawn yarn) Discharge condition shear Example 5 Nylon-6 having a relative viscosity in sulfuric acid of 3.2 was discharged into a spinning tube under non-quenching condition with the particular as follows, viz, the temperature of 290 C., the cylindrical holes of 0.2 mm. in diameter and 0.2 mm. in length, and the discharge rate of 8 and 10 g./min. Further corresponding to the varied discharge rate of 8 and 10 g./min., respectively rate of take-up of 500 and 600 m./min. was applied, and the so obtained undrawn filaments were both drawn by 3.03 times to be made into thick and thin yarns resembling that shown in FIG. 4. The thick and thin properties of the drawn yarns and undrawn filaments are shown in Table 5 below.

TABLE 5.THICK AND THIN PROPERTIES OF UNDRAWN FILAMENTS AND DRAWN YARNS When the drawn yarn of the Experiment 1 was plainwoven and dyed, the nodular parts (enlarged parts) thereof were dyed deeper to produce pepper-and-salt pattern, and the textile had pleasing luster and rough hand as well as desirable degree of stiffness and toughness.

Example 6 Nylon-6,6 having a relative viscosity in sulfuric acid of 2.8 was formed into yarn under the following conditions, viz, spinning temperature of 290 C.; a discharge rate of 6 g./min.; a discharging hole (diameter-length) of 0.2-0.2 (mm.); take-up rate 500 m./min., and draw ratio of 2.5x. Thick and thin yarn resembling that obtained in the Experiment No. 1 of Example 5 was obtained. Cross thread satin prepared from the same yarn used as the Woof and dyed had unique feeling in luster, hand, color tone and toughness different from those of similar fabrics prepared from conventional thick and thin yarn or modified cross-sectional fibers.

We claim:

1. A process for the preparation of thick and thin drawn nylon-6,6 yarn which comprises melting polyhexamethylene adipamide having a relative viscosity (1 as measured in 98% sulfuric acid at 25 C., within the range of 2.2-6.0, and extruding the resultant melt under the extrusion condition to exert the shear stress within the range defined by the formula 07.5 is S 1 063/ 0.

wherein 1' represents the shear stress (dyne/cm?) calculated from the following wherein P is the discharge pressure, R is the radius of holes in spinneret, L is the length of holes in spinneret, n is the tube length modification coefiicient and 1 has the above-defined significance; said extrusion being conducted under non-quenching condition.

2. The process of claim 1 in which the extruded yarn is further drawn in the direction of the length of the yarn. 3. A process for the preparation of thick and thin drawn nylon-6 yarn which comprises melting polycaprolactam having a relative viscosity (1 as measured in 98% sulfuric acid at 25 C., Within the range of 29, and extruding the resultant melt under the extrusion condition to exert the shear stress Within the range defined by the formula l0' l gT g2 X107 wherein T represents the shear stress (dyne/cm?) calculated from the following wherein P is the discharge pressure, R is the radius of holes in spinneret, L is the length of holes in spinneret, n

is the tube length modification coeificient and 1 has the above-defined significance; said extrusion being conducted under non-quenching condition.

4. A process for the preparation of a thick and thin yarn having at intervals enlarged parts of greater cross sectional area than that of the basic drawn filament parts, such thick and thin yarn being characterized by (a) the ratio of the cross sectional area of the basic drawn filament parts to that of the enlarged parts is 1:2-1z15;

(b) the enlarged parts are present with the frequency of at least per 30 mm. along the yarn length; and

(c) the cross sectional area of the thick and thin yarn is modified substantially continuously along the length of the yarn, such process comprising extruding a molten linear polyamide through a spinneret under such condition that the melt fracture occurs in the frequency of 10 'to 10 order per second and under non-quenching conditions.

References Cited UNITED STATES PATENTS 2,991,508 7/1961 Fields et al. 264176 3,127,915 4/1964 Bottomley 264167 X 3,236,914 2/1966 Murdock et a1. 260857 3,255,287 6/1966 Bottomley 264-167 3,303,169 2/1967 Pitz 260-857 X FOREIGN PATENTS 928,825 6/1963 Great Britain. 1,003,996 9/1965 Great Britain. 6,500,459 3/ 1965 Netherlands.

OTHER REFERENCES Fracture in the Extrusion of Amorphous Capillaries: by Tordella; I. of Applied Physics, 27 (5), pp. 454-458, May 1956. Scientific Lib. & 264/210 Literature D2.

DONALD J. ARNOLD, Primary Examiner.

I. H. WOO, Assistant Examiner.

US. Cl. X.R. 264-176, 210, 290

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